Thursday, June 30, 2022

Nocturnal Activities and Strategies for Self-Protection Against Human-Vectors Contact in a Peri-Urban Community in Lafia, Nasarawa State, Nigeria

 

Nocturnal Activities and Strategies for Self-Protection Against Human-Vectors Contact in a Peri-Urban Community in Lafia, Nasarawa State, Nigeria

 

Introduction

Mosquitoes are found in almost the entire globe [1] but are important vectors of several human diseases in tropical and subtropical regions of Africa [2,3]. The warmer climates in tropical areas allow mosquitoes to be active all year round, with the ideal conditions being hot and humid with moderate rainfall. In hot climates they are able to be more active, and the rainfall gives the mosquitoes aquatic sites for larval and pupal stages [1]. Mosquitoes are amongst the anthropophagic insects because they feed on human blood [4,5]. Mosquitoes are found in urban, peri-urban, and rural areas [6 - 9]. Deteriorating infrastructure, poor access to health, water and sanitation services, increasing population density, and widespread poverty contribute to conditions that modify the environment, which directly influences the risk of disease within the urban, peri-urban and rural ecosystem [10,11]. Mosquito vector species that have been shown to be favored by anthropogenic environmental change include Anopheles gambiae which transmits malaria parasite [12,13], Anopheles darlingi [14], and Culex nigripalpus which transmits Wucheraria bancrofti [15], and Aedes aegypti which transmits yellow fever virus [12,13].

Babamale et al. [16] opined that 96% of his respondents recognized mosquito as major transmitter of infections but only 22.6% had adequate knowledge of the correct transmission route. Only 13.2% mentioned Plasmodium species as the causative agent. The knowledge about the ecology of mosquito was greatly applauded in the study area. Health-seeking behaviours and possession of insecticidal treated bet net were found to be associated with socioeconomic status of individuals. The study by Oyewole et al. [17] showed that 13.8% of people in a Nigerian urban center cover cloth against mosquito bite followed by those who make use of mosquito repellant/insecticides spray 39 (9.8%) then door and window screening 37 (9.2%) while very few sleeps under net 17 (4.2%). A negligible proportion support environmental hygiene 26 (6.5%) as a means in which malaria transmission can be prevented.

Similarly, Celina et al. [18] reported that 48% of respondents in fourteen communities in Benue State had knowledge that malaria is caused by mosquito bite. Also, 20.7% attributed the cause of malaria to bad water and dirty water. Furthermore, 6.4% responded that malaria is caused by witchcraft. A total of 82.1% respondents had the knowledge that the best preventive practice is sleeping under nets followed by spraying insecticides (81%) then screening of windows with net (80%) which is also similar to report by Amaechi and Ukpai [19] and Eugene-Ezebilo [20]. An investigation by Msugh-Ter et al. [21] revealed that most students make use of window nets as protection against mosquito bites 77.7% (233/300) followed by insecticide treated nets and insecticidal sprays while very few respondents 0.7% (2/300) made use of mosquito weeds as repellents. The use of at least one form of control measure or the other is an indicator of high rate of mosquito’s bites in the University community.

According to Pam et al. [11], the first quarter of the year (January - March) was the period in which most inhabitants of a community in the lowland area of north-central Nigeria sleep outside, the night activity that a predominant number of the respondents do is just to spend time sitting outside the compound. Most of them sleep outside until it gets cold but not without covering themselves with a blanket and a few sleeps under insecticide treated nets. Although the inhabitants who sleep indoors mostly used insecticide treated nets as form of protection against contact with mosquito. A high proportion of individuals who responded to Pam et al. [11] in relation to being involved in night activities before going to bed said that they use protective covering while staying out at night. Others protect themselves when carrying out night activities by either warding off the mosquitoes or use repellants. Interestingly, a few individuals don’t worry themselves about mosquitos’ bites and some others don’t feel the bites.

The Mararraba-Akunza peri-urban settlement is a mix population which constitutes the sole inhabitants of the area and students of Federal University of Lafia that are probably not aware of the diverse mosquito species present in their locality and the health implication if beaten by an infected one. Also, there is no documented information on peri-urban dwellers nocturnal activities and strategies for self-protection against human-vector contact by households in Mararraba-Akunza, Lafia, Nasarawa State, Nigeria. Hence, the need for this study in order to contribute meaningfully to preventive and integrated control measures.

Materials and Methods

Study Site

The study was conducted in Mararraba-Akunza, with the coordinates 8°28’11.6004” N - 8°28’25.3524” S and 8°35’3.8364” E - 8°34’48.774” W in Lafia Local Government Area of Nasarawa State, Nigeria (Figure 1). Average temperature is about 26.8°C, humidity is relatively high, and rainfall is 456mm [22]. The site is a peri-urban settlement where agricultural activities take place.

Figure 1: Map of Lafia LGA showing Mararraba-Akunza area and map of Mararraba-Akunza area showing some specific physical features.

Ethical Consent

The Chief, elders and heads of households in Mararraba- Akunza community were visited and adequately informed on the importance of the research. Thereafter, the Chief and the households’ heads consented and granted permission for the research to be carried out by endorsing the ethical consent form.

Questionnaire Administration

Questionnaire Administration A well-structured questionnaire was administered to a total of 30 randomly selected households in December 2016.

Statistical Analysis

Data obtained were analyzed using R Console version 2.9.2. Pearson’s Chi-square test was used to compare proportions on the ways and attitude humans control mosquito bites in relation to sleeping points, main outdoor activities at night, the period they sleep in the open, length of stay outdoor as well as the forms of selfprotection for the following categories: age group, occupation, level of education, marital status and number of children. The level of significance was set at P < 0.05.

Results

Sleeping Points of Peri-Urban Dwellers of Mararraba- Akunza Area During Hot Months as well as their Forms of Protection at Outdoor Point

The result obtained showed that the number of males and females that sleep outdoors in hot months was 83.3% and 62.5% respectively as shown in Table 1. The overall number of people that sleep outdoors in hot months were more (66.7%) than those that do not (33.3%). Thus, there was a high significant difference (χ2 = 11.156, df = 1, P = 0.0008378, Table 1) between the number of people that sleep outdoors in hot months to those that don’t.

Also, a 100.0% of males and 95.8% of females use a form of protection against mosquito bite outdoor. The pool number of people that use a form of protection outdoor was 96.7% whereas only 3.3% don’t have any form of protection (Table 1). Hence, there was a very high significant difference (χ2 = 87.236, df = 1, P < 0.00001) between the number of people that use a form of protection outdoors to those that don’t.

Table 1:Number of People that Sleep Outdoors in Hot Months and those that use form of Protection Outdoors in Mararraba- Akunza, Lafia, Nasarawa State, Nigeria.

Main Outdoor Activities at Night

Table 2 shows that the main outdoor activity that predisposes the people to mosquito’s bite was watching television (50%) followed by just staying outside (46.7%) then socializing with friends (3.3%) while none of them was involved in drinking outdoor. Therefore, there was a high significant difference (χ2 = 26.267, df = 3, P < 0.01) in relation to outdoor activities that predisposes people to mosquito’s bite.

Table 2: Main Outdoor Activities at Night in Mararraba-Akunza, Lafia, Nasarawas State.

The Attitude of the People in Relation to Months (Quarterly Period) they Sleep in the Open as well as the Length of Outdoor Activity

The time of the year that inhabitants of the area mostly sleep outdoors are the months of January to March 19 (63.3%), followed by April to June 9 (30.0%), then July to September 2 (6.7%) and no one sleeps outdoor between October and December 0 (0.0%) as shown in Table 3. Thus, there was a very high significant difference (χ2 = 29.467, df = 3, P < 0.0001) in relation to the months people sleep outdoors. Also, their preference for length of outdoor activity is to stay till day break 21 (70.0%) than till late night 9 (30.0%) hours (Table 3). Hence, there was a significant difference (χ2 = 4.8, df = 1, P = 0.02846) between respondents’ preference in relation to length of outdoor activities.

Table 3: Months people of the peri-urban area sleep in the open as well as length of outdoor activity.

Ways of Self-Protection Indoors and Outdoors from Mosquitoes Bites

Table 4 shows that the most common way of self-protection in the indoor point against mosquitos’ bites was the use of bed nets 20 (66.7%) followed by those who use insecticide 6 (20.0%) while those that don’t use any form of protection were a few 4 (13.3%) and interestingly wrapper was not used by anyone as a form of protection indoors. Therefore, there was a very high significant difference (χ2 = 30.267, df = 3, P < 0.00001) in relation to the ways of self-protections by the people indoors. The protection used outdoors was mostly insecticide 13 (43.3%) followed by the use of bed nets 9 (30.0%) then those who use wrapper 7 (23.3%) while only 1 (3.3%) individual had no form of self-protection against mosquitoes bite (Table 4). Hence, the ways of self-protection outdoors by the people showed a significant difference (χ2 = 10, df = 3, P = 0.01857).

Table 4: Ways of self-protection indoors and outdoors from mosquitoes bites.

Discussion

The predominant number of males that sleep outdoor in Mararraba-Akunza connotes their high predisposal chances to mosquitos’ bites which may in turn counter interventions deployed as well as decrease manpower in farming activities in the area if such individuals eventually fall ill. This agrees with the finding of Pam et al. [11] who found that males were much more outdoor beyond 9:00 pm than females in Dokan-Tofa community in Shendam LGA of Plateau State, Nigeria. The pooled observed proportion of people that sleep outdoor at one time or the other as a habit during hot months was higher (66.7%) than those that do not sleep outside (33.3%) signifies the possibility of such population being susceptible to residual transmission of mosquito-borne diseases whenever there are suitable infected vectors for such transmission. This is in accordance with the finding by Monroe et al. [23] who observed that nearly all participants interviewed in northern Ghana sleep outdoors and are active. Similarly, Pam et al. [11] showed that over 60% of the interviewees in Dokan Tofa district, Shendam Local Government Area of Plateau State, North-Central Nigeria sleep outdoors. Consequently, Okumu et al. [24] opined that outdoor sleeping can be a major challenge to the control and eventual eradication of mosquitoes-borne diseases, most especially in tropical Africa.

Almost all (96.67%) the respondents protect themselves whenever they sleep outdoors which may limit mosquito-borne disease transmission risk. This is in line with the finding of Suchithra [25] in a study on determining the knowledge and practice regarding prevention of mosquito-borne disease among adult population in Athuru rural community in India who found out that 61% of the population showed good practice preventive measures against mosquitoes bites.

Main Outdoor Activities at Night

The main outdoor activity that exposes people to mosquito bite is watching television followed by just staying outside and no respondent was involved in drinking outdoor. This do not concur with Pam et al. [11] observed that most individuals spend time just sitting outside in their compounds as the main outdoor activity. Most males (66.67%) just stay out (hang out) while the females (54.17%) spent more time watching TV. This is in tandem with Pam et al. [11] who found a significant association between gender and staying outdoor beyond 9 pm by males. The highest proportions of outdoor activities at night were the watching of TV by age group 41- 50 years (60%) and students (100%) respectively. On the contrary, Pam et al. [11] revealed that inhabitants of Dokan-Tofa community of Shendam LGA in Plateau State of ages 21-31 years had the highest likelihood for staying out late while carrying out nighttime activities. Furthermore, Pam et al. [11] showed that occupation do not have significant influence in causing individuals stay outdoors late.

The Attitude of People in Relation to Months they Sleep in the open and Length of Outdoor Activity

The time of the year that inhabitants of the area mostly sleep outdoors are the months of January to March 19 (63.3%), followed by April to June 9 (30.0%), then July to September 2 (6.7%) and no one sleeps outdoor between October and December 0 (0.0%) as shown in Table 3. This is the time when environmental temperatures are accentuated just before the onset and during the early part of rainy season. The single, divorced and widow sleep in the open between January to march with the exception of the married respondents. This is in line with the finding of Pam et al. [11] who reported that the months of January and March witnesses the highest number of outdoor sleepers. A significant number prefer to stay till daybreak 21 (70.0%) than till late night 9 (30.0%). On the other hand, Pam et al. [11] recorded that a higher proportion of individuals (69.0%) slept until it gets cold.

Ways of Self-Protection Indoors/Outdoors from Mosquitoes Bites

The protection mostly used against mosquitos’ bites at the indoor point amongst the peri-urban dwellers of Mararraba-Akunza community is bed nets 20 (66.7%) but does not directly translate to using nets when sleeping outdoors at night due to the fact that they mostly use insecticide 13 (43.33%) much more over other protection measures. This corresponds with the study in Shendam LGA of Plateau State where it was observed that most inhabitants of Doka-Tofa community use insecticide-treated nets against contact with mosquitoes while sleeping indoors whereas at outdoor point they predominantly protect themselves from having contact with mosquitoes by covering up with blankets [11]. Consequently, the large-scale use of insecticide treated nets can modify feeding behavior thereby increasing exophagy in mosquito vectors [26]. There are those that ignore mosquitoes 1 (3.33%) or do not even feel their nuisance in the study area. Thus, this group are the most vulnerable to mosquito bite, and most exposed to diseases such as malaria. When most people are fast asleep at night are beaten by mosquitoes, whose population during the dry season is actually low [27,28] but have the capacity to transmit mosquito-borne diseases if they have bitten an infected individual.

Conclusion

The peri-urban inhabitants of Mararraba-akunza prefer to sleep outdoor during the hot months between January and March. Almost all respondents when resting outdoors use a form of protection against mosquito bite with the exception very negligible proportion that don’t protect themselves. The main outdoor activity that predisposes the people to mosquitos’ bites was watching television. Almost all respondents sleep till daybreak and majority of them use insecticide outdoors but when indoors they sleep under LLINs. The outdoor nocturnal activities of people in the study community will continually expose them to mosquito vectors bites due to high temperature and relative humidity that favours mosquitoes breeding success in lowland areas in which provision of stable power supply in peri-urban areas of Lafia metropolis will go a long way to minimize inhabitants’ outdoor stay and activities. Also, the government through Federal and State Ministries of Health as well as non-governmental organizations (NGOs) should make LLINs available all year round to peri-urban dwellers who constitutes very high population density in order for them to protect themselves both indoors and outdoors.

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Wednesday, June 29, 2022

Teaching Reform of Obstetrics and Gynecology Nursing Course in Higher Vocational Colleges Based on OBE Education Concept from the Perspective of Big Data

 

Teaching Reform of Obstetrics and Gynecology Nursing Course in Higher Vocational Colleges Based on OBE Education Concept from the Perspective of Big Data

 

Introduction

Obstetrics and gynecology nursing is one of the core courses of nursing specialty in higher vocational colleges. This course is opened in the third semester, with a total of 3 credits. This course is a key course for students to master before entering gynecology and obstetrics clinic. Through the study of this course, students are required to have solid professional knowledge and proficient practical skills. Therefore, this course needs to cultivate students’ clinical thinking ability and operation skills through the combination of theoretical knowledge and practical operation. The course team analyzed the current situation of the course of Obstetrics and gynecology nursing in Higher Vocational Colleges by using big data tools and found that the teaching materials of this course are relatively backward; The teaching mode is single; The assessment method is single; Students’ learning initiative is weak; The training of theoretical knowledge and practical ability. In this regard, our curriculum group adopted OBE teaching concept to reform the curriculum through comparison and exploration. OBE (outcomesbased education) means that the final results of teaching activities are presented by students’ learning outcomes. Students’ learning achievement is the maximum ability that students can achieve after a period of learning. Schools and teachers are required to make clear the students’ learning achievement, combine the diversified learning process and hierarchical learning requirements, and let students complete the challenge of self-realization through the learning process.

Teachers can feedback and improve the original teaching plan and teaching implementation by using the results. Secondly, the ways of enrollment in higher vocational colleges are diversified, students’ learning background is different, and the use of unified teaching materials in different learning situations obviously does not meet the needs of learning situation, which leads to the decline of students’ learning initiative and enthusiasm. Therefore, starting from the learning situation, the loose-leaf teaching material is used to deconstruct the knowledge system and framework, reconstruct the knowledge chain, reconstruct the teaching module, and teach at different levels according to the learning situation background. This course takes the female life cycle as the logic of the course and reconstructs the knowledge module of the course; Taking the students as the center, based on the training objectives of the five major learning areas of OBE, the differentiated teaching is designed, and the course implementation is carried out in the same class and heterogeneous way; With students’ learning achievement as the guidance, multiple assessment methods coexist and multidimensional assessment is carried out simultaneously; Based on the learning situation, starting from the needs, project-based teaching, students are the main body of the course; Integrated teaching of theory and practice [1,2].

In the course of teaching reform, how to reconstruct the teaching system, optimize the teaching content, improve the teaching methods, standardize the teaching process and improve the teaching evaluation as the main content, it is imperative for us to implement the teaching reform and practice of big data application technology course, and cultivate the compound talents with practical ability and technological innovation ability.

Construction of DQP Academic Framework Under OBE Teaching Concept

In 1981, American scholar Spady first put forward the concept of achievement-oriented education, and gradually formed a complete education system. The theoretical connotation is that students are the main body, and the ultimate learning achievement of students is the goal. From the setting of teaching objectives to curriculum design, curriculum implementation, curriculum evaluation are all result oriented, and then every link of curriculum implementation is deduced from the results. The DQP model is based on students’ learning outcomes. The main structure of DQP is composed of five institution specific areas and three academic levels, namely: professional knowledge, extensive and integrated knowledge, intellectual skills, applied and collaborative learning, citizen and global learning. Among the five learning areas, “extensive and integrated knowledge”, “application and collaborative learning”, “citizen and global learning” are the three areas emphasized in general education to achieve the teaching effect“Professional knowledge and intellectual skills are the two fields that put more emphasis on the requirements of students’ professional knowledge and skills. According to the theory of DQP, the five learning areas in the same level of academic structure combine the differences among different students, which can truly and uniformly reflect the ability evaluation standard. The three academic levels include associate degree, bachelor’s degree and master’s degree.

The differences in different academic levels mainly reflect the progressive relationship between the reference points of learning achievement requirements in the five major learning fields: the learning achievement requirements of all bachelor’s levels include the learning achievements of associate degree, and the learning achievements of all master’s levels also include the learning achievements of bachelor and associate degree. The requirements of learning outcomes at each level show the further challenges and skills that students need to deal with when they move from one degree to a higher degree. Through the spider web diagram of the five major learning fields, the unity of the evaluation of each educational level is intuitively reflected; The hierarchy of ability requirements; Comprehensive knowledge support and achievement embodiment [3] Figure 1. Taking the knowledge structure of the five learning fields as the framework template, students can change from “understanding, mastering and memorizing” in the previous curriculum standards to curriculum norms, including the process comprehensive assessment of “being able to say, be able to do, be able to solve, etc. “For example, DQP puts forward that “in a special field or a relatively common field of art and science, when doing a project, writing an article or program, or performing a performance, we can effectively find the information we need, classify the collected information, evaluate the usefulness of the information, and properly quote or apply the useful information to the project Article or scheme, performance “.

Figure 1: five learning areas.

For example, in order to cultivate students’ creative ability, teachers can carry out evidence-based analysis of clinical operation guidelines in the practical training of Obstetrics and gynecology nursing, let students divergent thinking, find evidence through empirical research to support existing views or improve existing views, innovate existing equipment, etc. We should cultivate and incubate valuable research to promote the progress of teachers and students. Students and teachers design together, verify the results together, learn together and grow together [4]. The form of curriculum assessment is not only reflected in knowledge memory and knowledge accumulation, but also focuses on the practicality of knowledge. At the same time, it combines the application and innovation of knowledge, which is well in line with the call of the country for innovation and entrepreneurship. Through the learning process of peer-to-peer curriculum, diversified curriculum achievements are reflected, and students’ learning process and skills are deposited in the display of learning achievements, which can be measured, evaluated, further corrected and improved. Verify the learning effect of students and reflect the teaching effect of teachers, so as to reverse design the course and further implement the classroom reform and optimization [5].

Through peer-to-peer learning process, diversified curriculum achievements are reflected, and students’ learning process and skills are deposited in the display of learning achievements. Through data comparison and analysis, students’ learning achievements can be measured, evaluated, and further corrected and improved. With the development and improvement of information technology, people’s learning methods and behavior habits have been gradually changed. The traditional teaching mode has been unable to meet the current teaching needs. Under the perspective of “Internet plus big data”, students have more learning means and various learning channels. Nowadays, most of the students in Higher Vocational Colleges grow up in the period of rapid development of information technology. They have a natural curiosity about new things and ideas. Their thinking mode and learning state are very different from those of the past. Through big data technology, students can search most of the content on the Internet. To a certain extent, it has changed the students’ learning style, and also provided some new ideas for the curriculum teaching reform in higher vocational colleges. Only by adopting the methods that students can accept, can the curriculum teaching be effectively changed. Through the analysis of statistical data to understand the teaching effect, verify the learning effect of students.

So as to feedback the teaching quality of teachers. Through the analysis and comparison of classroom data, we can reverse design the curriculum and further implement the classroom reform and optimization.

Curriculum Standard of Obstetrics and Gynecology Nursing

Teaching Content: According to the female life cycle, this course is designed into five modules: basic theory 2 class hours, including female reproductive system anatomy and physiology. 16 hours of gestational care, including pregnancy physiology to start the journey of life, prenatal examination to explore the secret of baby growth, prenatal examination to explore the mother’s secret, abnormal pregnancy to reveal the mother’s troubles. Childbirth care for 10 hours, including normal childbirth escort, abnormal childbirth race against the clock. 16 credits for gynecological diseases, including inflammation of reproductive system, tumor of reproductive system and endocrine diseases. 4 class hours for women’s health care.

Analysis of Learning Situation: We get a series of data by using questionnaire survey and other methods, and then use big data analysis method to get the students’ learning situation of this course. The specific performance of his learning situation is as follows. The student group of this course is the new generation after zero, which belongs to the third semester of nursing sophomore. This student group not only has the common characteristics of students of this age group, but also has the specific learning situation characteristics of students of this major. First of all, the new generation after 2000 is full of personality and curiosity about new things. They have strong hands-on ability. They don’t like to be limited and always have unlimited creativity, but they have certain shortcomings. For example, they are not willing to repeat learning and are not willing to train many times. Secondly, the proportion of male and female in nursing major is very different, female students account for 80% - 100% of the class on average, and the classroom activity is relatively low compared with ordinary classroom. In terms of basic knowledge, students have offered systematic anatomy, female physiology and other courses when they enter the course. Because the enthusiasm of students’ repeated learning is not high, so the mastery of theoretical knowledge is relatively weak. According to the learning characteristics of students, this course combs the preview before class through mind map and other ways, strengthens the review after class, and reviews the old to learn the new. In terms of basic skills, students have preliminary contact with nursing and obstetrics and Gynecology related skills, but their proficiency is not high.

In this regard, this course carries out situational guidance, optimizes training courses, refines training standards, and improves students’ enthusiasm through mutual training and evaluation. At the same time, the learning characteristics of this course are different from other courses. Because most of the students in the class are girls, they are very interested in exploring the secrets of pregnant mothers. It is very important for teachers to take the students’ interest as the ignition point, to stimulate the enthusiasm of students’ active exploration of learning, and to let the students become the main body of the classroom, active learning. In terms of learning characteristics, students like hands-on operation, but induction and summary, clinical thinking ability need to be improved. Through the project-based curriculum module, this course integrates knowledge and skills into vivid nursing cases and improves students’ problem-solving ability through case training. In terms of learning habits, students are willing to try to use intelligent mobile terminal devices to carry out learning, prefer personalized learning tasks, make full use of online teaching resources, carry out hybrid teaching, and respect and promote students’ personality development by personalized assessment of learning results. The new generation of post-Zero students have distinctive personality characteristics, strong innovation ability, but poor knowledge transfer ability. Therefore, it is necessary to teach students in accordance with their aptitude, improve classroom participation, and formulate executable training objectives that match the learning situation, which is the embodiment of OBE education concept [6].

Teaching Objectives

Overall Objective: By using big data analysis tools, we connect the knowledge points and skills of nursing practical jobs with our higher vocational obstetrics and gynecology nursing course, to implement the training program of nursing professionals and the curriculum standard of Obstetrics and gynecology nursing based on the analysis of learning situation. The curriculum design establishes a three-dimensional target system of knowledge, skills and quality, and designs the corresponding program outcome (POC) Figure 2. The objective of this course is to master the obstetrics and Gynecology professional knowledge, cultivate professional skills and promote the ability improvement. The three-dimensional objectives of this course include knowledge objectives, skill objectives and quality objectives. The training objectives of each dimension correspond to and match the relevant learning fields in DQP education framework structure. Knowledge objectives correspond to one credit of PoC1 professional knowledge in five major learning fields. Students can describe the core theories and practices in the field of nursing with relevant terms in the nursing field and solve the nursing problems in the professional field. The skill objectives correspond to the knowledge of poc2, poc3 intelligence, poc4 application and cooperative learning in the five learning fields. Poc2 is 0.5 credits in wide and integrated knowledge. Students can analyze a controversial problem (such as unprotected delivery, clinical treatment without payment ability) with knowledge of core areas learned, explain the clinical significance of the dispute, and explain their own opinions with the knowledge learned. Poc3 has 0.5 credits of intelligence skills and can use the knowledge learned to solve and coordinate the relationship between nurses and patients, medical care and nursing, and propose solutions for specific cases and revise the implementation plan.

Figure 2: learning target decomposition diagram.

Poc4 application and cooperative learning 0.5 credits, report at least one case related to the course in writing (such as head basin incorrect, multiple pregnancy, etc.) to explain how to apply the knowledge learned to clinical practice and to standardize clinical evaluation standards. The quality goal is 0.5 credits in poc5 citizens and global learning fields, that is, through the course learning, students participate in the relevant professional associations (including nursing health association and midwifery knowledge association) to skillfully operate maternal and infant nursing skills, make oral or written summary (report), and improve coordination ability, organizational ability and communication ability through organizational activities [6].

Expected Learning Results of Representative Courses: According to the characteristics of nursing specialty, we carry out three-dimensional education of people, and integrate the cultivation and practice of socialist core values into the teaching process of each class, so as to keep things fine and silent. Through the guidance of classroom thinking and politics, we should carry out labor education, life education, humanistic care, etc. In order to support and realize the achievement of POC, the corresponding “subject outcome” (SOC) [7] (Table 1).

Table 1: Comparison of learning outcomes and expected learning outcomes.

Analysis of Key and Difficult Points and Teaching Strategies: Based on the background of learning situation analysis, under the guidance of teaching objectives and professional norms, the focus of this course is to describe the pathogenesis and symptom characteristics of Obstetrics and Gynecology related diseases without error and complete the nursing operation of Obstetrics and Gynecology related diseases without error. We deconstruct and reorganize the curriculum according to the female life cycle and divide the curriculum into five modules. Now take module two pregnancy care as an example to choose the key and difficult points and corresponding teaching strategies (Table 2) [8].

Table 2: curriculum modules and teaching strategies.

Implementation and Effect of Classroom Teaching

Teaching Design Ideas: The teaching design is based on the analysis of learning situation which is gotten by big data analysis method, cognitive law of higher vocational students and industry orientation. 1: integrated teaching, this course adopts integrated teaching, takes the post demand as the classroom logic, combines theory with practice, so that students can learn by doing, practice in learning, and master knowledge and skills. 2: Double subject teaching, course teaching module, on campus and off campus training, practice together. School learning and job needs are seamlessly linked. That is: three stages of classroom teaching, preview before class, knowledge navigation, practice in class, knowledge consolidation, after class expansion, knowledge extension, learning for application, improve ability. This model highlights the progressive cultivation with students as the center, industry post skills as the basis, students’ learning achievements as the guidance and ideological and political education as the soul. This teaching mode realizes “three highs” of teaching effect, that is, high participation of students, high timeliness of learning process, and high personalization of learning results [9].

Teaching Implementation Process

Overall Curriculum Implementation: The teaching process can be divided into three stages: guidance before class, practice in class and development after class. Based on the teaching plan, the teaching activities strengthen the communication between students and teachers by means of information-based teaching. The information dissemination is timely and the distance between teachers and students is shortened. Through the comprehensive and continuous feedback, the evaluation and implementation of the whole teaching classroom and course teaching can complete a complete evaluation and diagnosis closed loop in the three stages of the teaching process““Learning to practice in class” is carried out with students as the main body and teachers as the guide. Each independent classroom is divided into four links of “leading people, entering and winning” (Table 3). Although this course focuses on adapting to clinical needs, it is impossible to include a large amount of knowledge in one class. Therefore, we focus on each class. Now to explore the baby’s Secret “abdominal four step palpations” as an example to show the four links. The first key word of classroom promotion is “lead”, that is, knowledge navigation. In this link, the teacher leads out the knowledge points of the course by cases, videos, high-quality questions, etc. The second key word of classroom promotion is “people”. In this link, the main body of the classroom is students. The teacher manages the classroom as a scaffold.

Table 3: “fascinating” four links.

Through the teacher’s demonstration, it shows a complete operation process or an independent case analysis, so that students can chain up the knowledge chain from point to area. The third key word of classroom promotion is “entering”. In this link from “people” to “entering”, the classroom initiative turns from teachers to students. Teachers help students to sort out the knowledge chain through the independent inquiry learning mode, sort out the knowledge fragments in the classroom, apply the knowledge points to various clinical situations, think independently and help each other to improve. Students sort out the knowledge chain, sort out the operation points and matters, from the simple memory of the second link to the reappearance and application of the third link knowledge, students repeat learning, active thinking. The fourth key word of classroom promotion is “win”. This link is the embodiment of learning achievements. Through the climbing of learning process, students and teachers grow together in the classroom, and teaching and learning are mutually beneficial [10].

Course Fragment Design: Taking the Course of Four Step Palpation of Abdomen as An Example

The teaching difficulty of this course lies in the operation method of abdominal four step palpation, and the judgment of fetal delivery mode, fetal presentation and fetal position. This class is divided into three stages (diagnosis closed loop) of pre class guidance, learning practice and after class development, with a total of 2 class hours. Guidance before class. Before class, teachers publish the preview materials to the information-based teaching platform and push them to the wechat end of students’ mobile phones. The teacher analyzed the preview results, understood that the students’ judgment on the mode of delivery, fetal presentation and fetal position was weak, and they had a good grasp of the purpose of abdominal four step palpation, and finally determined the teaching plan [11].

After Class Development: After class exercises were pushed through the teaching platform which si established by big data system, and the after-class exercises were mainly based on the real questions of nurses’ qualification examination to prepare for the students’ nurses’ qualification examination. Answer questions in WeChat group, shorten the distance between teachers and students, and break the time and space restrictions of the classroom. Relevant knowledge is released through the platform of student associations, and professional associations organize knowledge and skills competitions.

Teaching Evaluation

The three-dimensional evaluation promotes the effectiveness, through students’ self-evaluation, students’ mutual evaluation and teachers’ comments, The big data system is used to collect the above three-dimensional evaluation information, the three-dimensional degree can understand the knowledge mastering situation, at the same time, through role perception and mind map, summarize the learned knowledge, cultivate students’ ability to build a systematic and rigorous knowledge structure, and promote students’ learning effectiveness. The assessment of students’ performance should change the traditional single assessment method of theoretical knowledge, pay attention to the comprehensive assessment of students’ learning attitude, thinking ability, practical ability and problem-solving ability, and objectively evaluate the students’ learning situation. Curriculum assessment is closely related to medical practice, and knowledge and skills are consistent with the national nurse qualification certificate assessment, higher vocational education personnel training mode and 1 + X certificate system. The assessment subjects are diversified. The evaluation data adopts wide-angle evaluation, including students’ selfevaluation, group mutual evaluation, course teacher’s comments, and clinical teaching teacher’s comments, striving for multi angle evaluation and multi angle improvement from knowledge to skills, skills to ability [12].

Implementation Effect

This teaching mode realizes the “three highs” of teaching effect, that is, high participation of students, high timeliness of learning process and high personalization of learning results. Students’ participation is high. The whole classroom teaching is completed in the environment of integration of theory and practice, which promotes students’ participation and self-confidence, and improves their ability of knowledge transfer and application. Compared with the traditional teaching, the effect of teaching reform is obvious. The efficiency of learning process is high. The teaching process is streamlined, and the diagnosis closed loop is formed. The efficient teaching implementation has been achieved, and the basic teaching objectives have been basically achieved. Learning outcomes are highly personalized. In and out of class, students are encouraged to discover and develop their own interests and expertise. Students actively participate in personalized learning results display and exchange activities and enhance their learning initiative and initiative.

Teaching Characteristics and Reflection

Since January 2014, we have been carrying out the practical research on the curriculum reform of Obstetrics and gynecology nursing in Higher Vocational Colleges Based on the OBE education concept from the perspective of big data. We have been deepening the reform, the teaching effect has been continuously improved, and the students’ ability has been continuously improved [13]. Before the teaching reform, the average score of Obstetrics and gynecology nursing course was only (73. 94 1 ± After the reform, the average final score of each semester was (88.72 10.60) ± Through big data analysis, students’ satisfaction with the course was 90.41 points, which were higher than that before the implementation of the reform. The students’ passing rate of the examination was significantly improved, and their learning initiative and enthusiasm were also greatly improved. According to the comparison between (Table 4) (assessment of Obstetrics and gynecology nursing in June 2014 - before the education reform) and (Table 5) (assessment of Obstetrics and gynecology nursing in the second semester of 2020-2021 academic year - after the education reform), We get the following conclusions: from the perspective of big data, based on the OBE education concept, the practical research on the curriculum reform of Obstetrics and gynecology nursing in higher vocational colleges has greatly improved students’ mastery of the knowledge points and operation skills of Obstetrics and gynecology nursing, greatly improved their autonomous learning ability, and cultivated students’ lifelong learning ability.

Table 4: Assessment of Obstetrics and gynecology nursing in June 2014 (before education reform).

(Notes: No.=Number, Per.=Percentage)

Table 5: Assessment of Obstetrics and gynecology nursing in the second semester of 2020-2021 academic year (the latest year after the education reform).

(Notes: No.=Number, Per.=Percentage)

Especially, From May 2021 to now, during the New Coronavirus epidemic in Guangzhou, we used the big data system to carry out online teaching, uploading a large number of teaching video screens, chapters of the target test questions and comprehensive exercises to the database, and set the teaching video screen as playback status in the database, so that students can use fragmented spare time to learn repeatedly. Master the key and difficult points thoroughly. The teaching effect is greatly improved. Teachers use the big data system to arrange a large number of extracurricular research topics and course papers and require students to use the Internet and big data to search for information in the system. Students can make full use of big data system and computer network system for conscious learning, in-depth learning, and complete course papers and research topics, which greatly improves students’ scientific research and innovation ability and cultivates students’ pioneering spirit. It creates a new mode of Higher Vocational Education from “teachers want students to learn” to “students are willing to learn”, which lays a solid foundation for higher vocational education to cultivate more and better high skilled talents to meet the needs of society, and makes due contributions to the development of nursing and Health Management College of Guangdong Lingnan vocational and technical college, At the same time, it has also explored some experience reference for the higher vocational colleges of nursing medicine, which benefit more students, teachers and colleges. Therefore, from the perspective of big data, the practical research on curriculum reform of Obstetrics and gynecology nursing in Higher Vocational Colleges Based on OBE education concept has created great social benefits.

The starting point of education is not knowledge, but people, and it is the object of our education.0be teaching concept is student-centered, based on the learning background to set up courses, from curriculum design, curriculum implementation, curriculum evaluation, and through the results of reverse design courses, modify the classroom implementation, form an effective classroom teaching closed loop, so as to implement the curriculum objectives, realize the requirements of five major learning areas of professional talent training. The curriculum reform of Obstetrics and gynecology nursing based on OBE education concept is based on the “123 teaching mode” of work study combination based on the analysis of learning situation, cognitive law of higher vocational students and industry orientation. This model highlights the progressive cultivation with students as the center, industry post skills as the basis, students’ learning achievements as the guidance and ideological and political education as the soul. This teaching mode realizes the “three highs” of teaching effect, that is, high participation of students, high timeliness of learning process and high personalization of learning results. The teaching process can be divided into three stages: guidance before class, practice in class and development after class. Each teaching link has assessment and diagnosis, which provides reference data for the next link.

Through the comprehensive continuous evaluation and feedback, the evaluation implements the whole teaching classroom and course teaching, so that the three stages of the teaching process complete a complete evaluation and diagnosis closed loop. Through knowledge learning, school skills practice, clinical skills observation and internship, clinical hospital internship progressive extended learning space, multi angle and multi-level cultivation of students’ clinical comprehensive quality and nursing professional quality. From simulated training to feeling the relatively real work scene, observing the clinical operation process to using skills to solve practical clinical problems, the separation between classroom learning and post, progressive extension of learning space and zero gap connection between major and post have been solved [13]. Education is a subject that is constantly being revised, just like the endless curriculum reform. The introduction of OBE teaching concept, through the feedback of learning results to modify the classroom. In the course reform, we find that the new generation of students have unlimited potential, unlimited creativity, and each has its own characteristics. The significance of education is to respect each individual’s progress and personality. Therefore, we are still thinking about how to refine the measurement standard of learning outcomes, further humanize and personalize the quantitative results, and respect each individual learning process and output.

Summary

Finally, it should return to our teaching goal: from professional knowledge to methods and abilities, and finally reflect the students’ social adaptability and ability to produce gradient climbing. Any teaching method is not an isolated way, it needs absorb anything and everything. Any kind of teaching method is not only suitable for a course, but also can be copied and improved, and suitable for more subjects; Any kind of teaching method is not only aimed at a certain group of people, but it should also be adjusted through “teaching students in accordance with their aptitude”, so that more students can use it and produce greater learning influence. In the theme of education, students should pay attention to their interests; Starting from the major, students should pay attention to it; Starting from emotion, arouse students’ resonance [14]. From the perspective of big data, based on the OBE education concept, a series of reforms of Obstetrics and gynecology nursing courses in higher vocational colleges have been carried out for many years. The practice shows that the knowledge and skills of Obstetrics and Gynecology Nursing of higher vocational college students have been improved rapidly, their ability to analyze and solve problems has been greatly strengthened, their graduates are more popular in the society, and the popularity and reputation of higher vocational colleges have been improved, The number of students registered for Guangdong Lingnan Institute of Technology is also increasing year by year, forming a virtuous circle, which promotes the further development of College of nursing and health of Guangdong Lingnan Institute of Technology.

Therefore, it is very urgent to continue to promote a series of reform of Obstetrics and gynecology nursing curriculum in Higher Vocational Colleges Based on OBE education concept from the perspective of big data, and keep pace with the times, constantly promote the achievements and experience of teaching reform, and promote the teaching reform to a deeper and broader direction. In particular, how to make good use of the Internet for Teaching Reform [14], how to make better use of big data to carry out indepth teaching reform research of Obstetrics and gynecology nursing course in Higher Vocational Colleges Based on OBE education concept from the perspective of big data are our future efforts.

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Tuesday, June 28, 2022

Cobalt Doped TiO2/rGO Nanocomposites as Highly Efficient Photocatalyst for Water Purification

 

Cobalt Doped TiO2/rGO Nanocomposites as Highly Efficient Photocatalyst for Water Purification

 

Introduction

Photocatalysis is a crucial research filed, which solves the problem of energy and environmental pollution in the world in an economical and sustainable way [1]. Titanium dioxide (TiO2), as the most common candidate among various semiconductor photocatalysts, has been widely utilized in the environmental filed because of its high activity, long-term stability and low toxicity [2-6]. However, because of its wide band gap (Ebg≈3.2eV for anatase type TiO2) and high recombination rate of electron-hole pairs, TiO2 can solely adsorb the UV light which is merely 3~5% of solar spectrum, resulting in low utilization of the majority of the solar energy [7-9]. In order to overcome these drawbacks, various improvement methods have been explored including heterogenous composition [10,11], element doping [12,13], surface modification and the like. Among them, the element doping of TiO2 photocatalysts has been considered as a feasible method to improve the interfacial charge-transfer efficiency, narrow the band gap and delay the recombination of carriers. Up to now, transition metal such as Co [14,15], Pt [16], Sn [17] and Fe [18] has been reported to be successfully doped into TiO2, and the light response wavelength of the obtained materials showed significant red-shift. According to literatures, transition metals cobalt is considered as one of the best candidates to reduce the electron-hole recombination rate and transfer the adsorption edge to the visible light region [19- 21]. The cobalt oxide-loaded TiO2 (TiO2-CoO) support with reduced graphene oxide (rGO) was fabricated by sol-gel method and utilized to remove 2-chlorophenol (2-CP).

The removal efficiency of 2-CP was 98.2% with the ternary nanocomposite in the visible region [22]. The ternary rGOTiO 2/Co3O4 nanocomposites were successfully prepared by coprecipitation method, and exhibited the highest degradation performance of methylene blue (MB) and crystal violet (CV) dye under visible light [23]. As a result, cobalt doped TiO2 photocatalysts have shown superior performance in degrading various organic pollutants. Graphene oxide (GO), due to its excellent electrical conductivity, large surface area and chemical stability, has attracted wide attention as a substrate for promoting the uniform distribution of heterojunction materials and enhancing the photocatalytic activity [24-28]. Due to the conjugated structure of GO, the nanocomposite of modified TiO2 supported with graphene oxide were the perfect combination to enhance the charge separation during the electron-transfer processes. Therefore, the coupling of graphene oxide with some semiconductors has received particular attention in recent years [6]. In this paper, Cobalt doped TiO2/rGO composites was successfully fabricated through hydrothermal method for MB degradation. The results demonstrated that the Co- TiO2/rGO composites remarkably enhanced the MB degradation efficiency. Furthermore, recycling degradation experiments revealed excellent stability of the fabricated Co-TiO2/rGO nanocomposites for treatment of target contaminant.

Materials and Methods

Materials

Cobalt nitrate hexahydrate (Co(NO3)2·6H2O, 98%), Tetrabutyl titanate (C16H36O4Ti), glacial acetic acid (C2H4O2), ethanol (C2H5OH) and macrogol 400 (HO (CH2CH2O) n H) were obtained from He Dong Hong Yan reagent factory of Tian Jin. Natural flake graphite (≥99.85%) was purchased from Sinopharm Chemical Reagent Co. Ltd.

Catalysts Synthesis

Co-TiO2 catalysts were prepared by one-step hydrothermal method. In a typical synthesis procedure, 10mL tetrabutly titanate was dissolved in ethanol (20mL) to form homogenous solution “A”, whereas 0.02g Co (NO3)2·6H2O dissolved in a solution of ethyl alcohol, glacial acetic acid, macrogol 400 and deionized water to form solution “B”. Subsequently, solution “A” was introduced into solution “B”, and the obtained dispersion was heated at 180 °C for 5h. In following step, the prepared catalysts were washed by centrifugation with ethanol and dried at 80 °C. The obtained composites were light yellow particle and calcined in a muffle furnace at 500 °C for 3h, and the obtained sample was named as Co- TiO2. The GO was synthesized by modified Hummers method. 20mg GO powder was dispersed in a solution of deionized water (40mL) and ethanol (20mL) through 30min ultrasonic, and then 200mg Co-TiO2 was introduced to the GO suspension under vigorous stirring. Subsequently, the solution was heated at 140 °C for 5h. The resulting precipitate was washed with deionized water and dried at 80 °C. The final composites powders were labelled as Co-TiO2/rGO- 2. For comparison, the samples prepared by adding 10mg, 30mg GO powder were denoted as Co-TiO2/rGO-1 and Co-TiO2/rGO-3, respectively.

Characterization Methods

The purity and crystallinity of the prepared samples were collected by Bruker D8 Advance X-ray diffraction (Germany) with Cu Kα radiation. The morphology of the photocatalysts was characterized via Scanning electron microscope (Hitachi SU-4800). The Ultraviolet-Visible (UV-Vis) diffuse reflectance spectra (DRS) were implemented by using UV-3600 Plus. X-ray photoelectron spectroscopy (XPS) were obtained by ESCALAB 250XI (ThermoFischer Electron Corporation, USA). Electrochemical measurements were carried out on CHI 660E electrochemical workstation.

Photocatalytic Degradation

The photocatalytic efficiency of Co-TiO2/rGO samples was investigated with MB degradation under visible light. The visible light source was Perfect 300W Xe-lamp (with a 420nm cut-off filter). In each experiment, 20mg of Co-TiO2/rGO composite were added to 150mL MB solution (20mg/L). The suspension was stirred in the dark for 60min to ensure the attainment of adsorption-desorption equilibrium. 5mL sample solution was extracted at predetermined time and analyzed by UV-3600 plus. The removal efficiency (R) of MB was calculated by Eq. (1).

It was expected that the degradation of the MB obeyed the pseudo-first-order reaction kinetics as follows:

where C0 (mg/L) was the initial concentration of MB, Ct (mg/L) was the concentration of MB at time t, k was the kinetic constant.

Results and Discussion

Structure Characterization

Figure 1 were the XRD patterns of the as-prepared nanocomposites. It was clear that all samples exhibit similar diffraction peaks. The peaks located at 2θ = 25.34°, 37.85°, 47.99°, 54.04°, 62.67°, 68.79°, 70.31°, 75.05° and 82.49°, which could be indexed to (1 0 1), (0 0 4), (2 0 0), (1 0 5), (2 0 4), (1 1 6), (2 2 0), (2 1 5) and (2 2 4) planes of anatase TiO2, demonstrating the high purity and good crystallinity of the samples [29]. The diffraction peaks of Co were not observed, which might be owing to the low content of Co (NO3)2· 6H2O or the cobalt ions were uniformly dispersed into the anatase crystallites. It was noteworthy that the peak intensity corresponding to the (2 1 1) crystal plane in the cobalt-doped nanocomposites varied, indicating that the presence of Co2+ ions around Ti4+ [30]. No significant diffraction peaks were noticed for XRD patterns of Co-TiO2/rGO nanocomposites when compared with Co-TiO2 nanoparticles, which was described the low rGO content in the composite, or of the TiO2 loading on the rGO surface [31,32]. Surface morphology of the as-prepared composites was assayed through SEM analyses. It could be seen from Figure 2a that the Co- TiO2 particles were subsphaeroidal and well-dispersed. Figure 2b showed that the agglomeration occurred when subsphaeroidal Co- TiO2 particles were combined with graphene sheets. The element composition of the Co-TiO2/rGO-2 nanocomposites were confirmed by EDS analysis. In the element mapping images (Figures 2c & 2d), C, Ti, O and Co disperse uniformly in the selected area of Co-TiO2/ rGO-2, suggesting that cobalt atoms were successfully doped into the composites. According to these images, the cobalt atoms were evenly distributed in TiO2 particles, indicating that the interaction between cobalt and TiO2 particles was excellent in the hydrothermal synthesis procedure [15].

Figure 1: XRD patterns of

a) TiO2;

b) Co-TiO2;

c) TiO2/rGO;

d) Co-TiO2/rGO-1;

e) Co-TiO2/rGO-2;

f) Co-TiO2/rGO-3

Figure 2: SEM images of

a) TiO2;

b) Co-TiO2/rGO-2;

c) C and

d) EDS analysis of Co-TiO2/rGO-2.

The chemical oxidation state of Co-TiO2/rGO-2 nanocomposites were measured by XPS analysis (Figure 3). As shown in Figure 3a, the XPS survey spectrum of the Co-TiO2/rGO-2 presented that C, O, Ti and Co elements could be revealed, which could consistent well with the result of EDS element mapping. The spectrum of Ti 2p (Figure 3b) exhibited two main peaks at 464.2 and 458.4eV, which were assigned to the Ti 2p1/2 and Ti 2p3/2 [33]. The C 1s spectrum of Co-TiO2/rGO-2 composite was fitted into four peaks at 292.3eV, 288.1eV, 285.9eV and 284.3eV, which were signed to C= O, C= O= C, C= OH and C= C/C= H, respectively [34,35]. In the Co 2p core level of the Co-TiO2/rGO-2 nanocomposites (Figure 3d), the peak appearing at 781.2 corresponded to Co (II) ions [36,37]. The optical property of TiO2 and Co-TiO2/rGO was inspected by UV-Vis adsorption spectra, as displayed in Figures 4a & 4b. Pure TiO2, with equal to 3.18eV and adsorption edge at 390nm, showed almost no visible light adsorption. Compared with the adsorption edge of pure TiO2, a strong light adsorption intensity at approximately 430nm was observed for the Co-TiO2/rGO-2 composites, which was associated to the formation of Ti-O-C bonds, resulting in reduced excited photons energies and hence low band gap energy [38]. As a result, the visible light adsorption efficiency of Co-TiO2/rGO-2 can be effectively enhanced due to the cobalt cations and rGO, which is beneficial to improving the photocatalytic degradation activity.

In order to reveal the behaviors of charge transfer and separation in the prepared photocatalysts, the photocurrent response and electrochemical impedance spectroscopy (EIS) were recorded [39]. Figure 4c showed the transient photocurrent responses of TiO2, Co-TiO2 and Co-TiO2/rGO-2 composites. It could be found that the photocurrent densities of Co-TiO2/rGO- 2 composites were significantly higher than that those of other samples, implying the efficient separation efficiency of electronhole pairs. Figure 4d exhibited EIS changes of TiO2, Co-TiO2 and Co- TiO2/rGO-2 composites. It was clearly observed that the Co-TiO2/ rGO-2 possessed much smaller arc radius relative to TiO2 and Co- TiO2, indicating that Co-TiO2/rGO-2 had lower resistance and faster separation of electron-hole in the charge transfer processes, which could well correspond to the photocurrent results.

Figure 3:

a) Full XPS spectrum and high-resolution spectrum of

b) Ti 2p

c) C1s and

d) Co 2p

Figure 4:

a) UV-Vis diffuse reflectance spectra of TiO2, Co-TiO2, TiO2/rGO and Co-TiO2/rGO;

b) Plot of Kubelka-Munk function versus band gap energy of TiO2, Co-TiO2 and Co-TiO2/rGO-2;

c) The transient photocurrent density of TiO2, Co-TiO2 and Co-TiO2/rGO-2;

d) Electrochemical impedance spectra of Nyquist plots of TiO2, Co-TiO2 and Co-TiO2/rGO-2.

Photocatalytic Performances

The photocatalytic performances of the TiO2, Co-TiO2, TiO2/rGO and Co-TiO2/rGO composites were evaluated by degradation MB. As exhibited in Figure 5a, the Co-TiO2/rGO-2 nanocomposites had the highest photocatalytic performance. For pure TiO2 nanoparticles, only 57.4 % of the MB was removed following 210 min under visible light irradiation. Nonetheless, the removal percentage of MB by TiO2/rGO and Co-TiO2/rGO-2 nanocomposites was 83.5% and 99.7%, respectively. The enhanced activity of the Co-TiO2/rGO-2 nanocomposites might have been attributed to the introduction of Co ions and rGO. Figure 5b manifested the kinetic constant (k) of the as-prepared photocatalytic. The k value of pure TiO2 and TiO2/ rGO were 0.0025 and 0.0063 min−1, respectively. While the Co-TiO2/ rGO-2 nanocomposites exhibited the highest MB photodegradation rate (0.0125 min-1), which was almost 5 and 1.98 times faster than those of the TiO2 and TiO2/rGO, respectively. To identify the optimum dosage of the photocatalyst, a series of experiments were carried out by varying the concentration of catalyst from 10mg to 40mg in 150mL of MB (20mg/L) (Figure 5c). It was realized that the removal efficiency of MB increased from 69.3% to 99.7% with the Co-TiO2/rGO-2 nanocomposites increased from 10mg to 20mg, which was ascribed to the availability of enough active sites on the catalyst surface. Whereas the remove efficiency decreased with a further increase in the Co-TiO2/rGO-2 dosage, which was ascribed to the agglomeration of the photocatalyst. Based on the above results, the optimal dosage of Co-TiO2/rGO-2 nanocomposites for MB degradation was to be 20mg. The stability and recyclability of the photocatalyst exerts great impact on the operating cost of wastewater treatment. Therefore, the stability of the photocatalysts was evaluated for the Co-TiO2/rGO-2 nanocomposites and the results were showed in Figure 5c. The study indicated that the removal efficiency of MB was still 78.2% after five recycling runs, indicating the activity of the recovered Co-TiO2/rGO-2 was stable enough for recycling. Therefore, Co-TiO2/rGO-2 nanocomposites were expected to be promising in environmental remediation because of their excellent photocatalytic activity and stability.

Figure 5:

a) Photodegradation of MB under simulated solar irradiation over the as-prepared photocatalytic;

b) The kinetic constants of the as-prepared photocatalytic for the MB photodegradation;

c) Efficient of the dosage of the MB photodegradation by Co-TiO2/rGO-2;

d) Effect of cycling times on photocatalytic efficiency on Co-TiO2/rGO-2

Proposed Mechanism for Photocatalytic Degradation of MB

To determine the active species (such as •OH or h+ or •O2 - radicals) and further explore the photodegradation mechanism, isopropyl alcohol (IPA), ammonium oxalate (AO) and 1,4-benzoquinone (BQ) were used as the radical scavengers [40,41]. The experiment data revealed that the photocatalytic activity of Co-TiO2/rGO-2 was decreased by adding the radical scavengers but to different degrees (Figure 6), indicating that all the above active radical species were responsible for the MB degradation. Notably, the photocatalytic performance dropped sharply to 61.1% with the addition of IPA, demonstrating that h+ radical was the main active species in the MB degradation process. Based on the above characterization and photocatalytic activity results, a plausible mechanism of Co-TiO2/ rGO-2 for MB degradation has been proposed and shown in Figure 7. The improvement of TiO2 photocatalytic performance could be explained as follows:

1) The doping of optimal Co2+ into the lattice of TiO2 nanosheet could efficiently reduce the band gap width of TiO2 and increase the adsorption of visible light [42,43].

2) The specific surface area of the composite increased due to adding rGO, and more active sites could be provided for photocatalytic activity [44].

3) Under the excitation of visible light, the electrons generated by the conduction band of TiO2 were captured and transferred by the graphene layer, which improved the electron-holes separation efficiency [45,46].

The electrons subsequently react with the oxygen molecules adsorbed on the surface of the catalyst to generate •O2 - to degrade MB. At the same time, the residual h+ within the TiO2 VB can be directly or through water oxidation to generate ·OH radicals, and in turn photo oxidize of MB [15]. In summary, the addition of Co metals to TiO2/reduced graphene oxide composite have demonstrated to be beneficial for degrading MB, which was consistent with the electrochemical measurements. The synergy effects of Cobalt doped TiO2 and rGO was conducive to the formation of the active sites and the facilitation of the high photocatalytic performance. Therefore, Co-TiO2/rGO composite offered an excellent combination of high activity and long-term performance durability.

Figure 6: Effects of radical scavengers on the degradation of MB over Co-TiO2/rGO-2 nanocomposite.

Figure 7: The probable photocatalytic degradation mechanism for MB by the Co-TiO2/rGO nanocomposites.

Conclusion

In conclusion, an efficient Cobalt doped TiO2/rGO photocatalyst was successfully prepared, and the properties of Co-TiO2/rGO nanocomposites were investigated. It was noticed that the Co-TiO2/ rGO-2 revealed an excellent photocatalytic performance in the MB degradation process. Compared to TiO2, MB degradation percentage was increased from 57.4% to 99.7% in the existence of Co-TiO2/rGO- 2. This phenomenon could be explained as the special properties of reduced graphene oxide components and cobalt dopant, which facilitate the separation of photo-generated carries and extend the adsorption spectrum of TiO2 into visible region. Furthermore, the degradation percentage of MB was still obtained to 78.2% after five cycles. Therefore, Co-TiO2/rGO nanocomposites have promising applications in degradation of the organic compounds in the coloring, petroleum and leather industries.

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Monday, June 27, 2022

Epigenetic concerns in therapy for Chronic Obstructive Pulmonary Disease

 

Epigenetic concerns in therapy for Chronic Obstructive Pulmonary Disease

 

Introduction

COPD (Chronic Obstructive Pulmonary Disease) is a prevalent chronic adult disease that, by 2020, will be the world’s 3rd leading cause of death. COPD is characterized by Mucociliary dysfunction, lung inflammation, airway fibrosis, and alveolar destruction [1]. There are many factors at hand, such as chronic inflammation, the theory of elastase/anti-elastase, apoptosis, the balance of oxidantantioxidant, and infective repair that cause COPD pathogenesis [2,3]. Cigarette smoke contains over 4700 organic compounds and 1014 free radicals/oxidants, making it the primary source of COPD and inflammation [4]. It stimulates multiple redox-sensitive transcription factors such as NF-kB (nuclear factor kappa-B), most important to increased pro-inflammatory cytokine and chemokine assembly in COPD [5,6]. Post-translational changes in histone and other DNA proteins are known as epigenetic alterations [7]. Without altering the primary gene sequence, DNA methylation and histone methylation can influence gene expression such as post-translational histone protein modifications are acetylation, phosphorylation, and ubiquitination (H2A, H2B, H3, and H4) [8].

Methylation of DNA, which is catalyzed by DNA Methyltransferase (DNMT) family members, which is also the primary epigenetic process in methyl groups are attached to cytosine residues in Cytosine Phosphate-Guanine (CPG) [9,10]. Hypermethylation of DNA in CpG island gene promoter regions result in gene silencing, while hypomethylation results in DNA transcription activation [9]. Histones are essential protein components of chromatin. Chromatin consists of H-linker and octamer protein containing two copies of each H2A, H2B, H3, and H4 core histone where DNA is wrapped [11]. H3K4me3, H3K9me3, and H3K27me3 are modifications of histones that play a significant role in controlling genes. The activation of gene expression with H3K4me3, but gene expression is associated with H3K27me3 and H3K9me3 [11].

DNA Modification in COPD

The same DNA sequence can be found in all of an organism’s cells. Thus, with the aid of epigenetic control, the genome is organized into ‘heterochromatin’ (compact) and ‘euchromatin’ (accessible) regions to ensure the right transcriptional program in a particular cell type. Changes in DNA alteration may explain some of the considerable variations in smokers’ vulnerability to developing COPD. Indeed, 349 Cytosine phosphate Guanine (CpG) sites were confirmed to be significantly associated with the intensity of COPD and the reduction in lung function by large-scale genome-wide investigations of DNA methylation marks (27,000 genes) [12]. Cigarette smoking (CS) condensate can cause multiple CpG targets in small human airways and bronchial epithelial cells to hypo or hypermethylation [13]. Changes in DNA methylation patterns have been found to enhance histopathology based on the experiment carried out on mice for smoke exposure. Similarly, DNA methylation caused by various dangerous elements may increase the sensitivity of COPD to a subsequent insult. This is confirmed by the transparency of pre-birth cigarette smoke affects explicit CpG DNA methylation in detoxification characteristics worldwide and performance. This also leads to constant effects, such as decreased lung work in young people [14,15]. Previously Georgiou, et al. [16], proved that chronic smoking is associated with increased methylation of a known tumor suppressor, p16 promoter, or aryl hydrocarbon receptor repressor; changes in DNA methylation status following smoke exposure can explain the altered expression in DNMT (DNA methyltransferase).

This subject has only been marginally debated about lung cancer, but not concerning COPD. CS exposed human bronchial epithelial cells had lower levels of DNMT1 and higher levels of DNMT3b [13]. On the other hand, CS elevated DNMT1 levels in A549 cells, while DNMT3b downregulation triggered synuclein-gamma demethylation, a prometastatic oncogene. DNMT1, DNMT3a, and DNMT3b proteins are significantly elevated in patients with lung tumors [17]. In addition, nitrosamine ketone (NNK) obtained from tobacco-specific carcinogenic nicotine-induced nucleus aggregation of DNMT1, accompanied by hypermethylation of the tumor suppressor gene in mice and lung cancer patients who regularly smoked [13]. Polycomb group (PcG) proteins were discovered for the first time in Drosophila melanogaster, and they represent a novel epigenetic control region. The Polycomb target gene RUNX3, a tumor suppressor gene, is associated with promoter methylation and CS [18]. Besides, it has been demonstrated that CS condensate silences tumor suppressor miRNA, miR-487b expression epigenetically. In lung epithelial and lung cancer cells following CS treatment, PRC-mediated DNA methylation and altered nucleosome location within the miR-487b region were observed [19].

DNA Methylation and COPD

DNA methylation is revealed to play a critical function in the existence and output of COPD; CS modifies the DNA methylation by triggering inflammatory responses and causing diseases such as COPD [12]. Macrophages are innate immune cells that directly affect the polarization of innate and adaptive immunity and eliminate by lung macrophages of bacteria [20]. Usually, COPD arises with upper lobe predominance, and tests have demonstrated anatomical variation in ventilation and oxygenation of the upper and lower lung lobes [21]. The main ways of modifying epigenetics DNA methylation shows in (Figures 1 & 2).

Figure 1: The main ways of modifying epigenetics. DNA methylation, histone methylation are involved in most epigenetic modifications. The action of DNA methyltransferases can regulate DNA methylation (DNMT). Modifications of histones are mainly expressed in acetylation. Mediated by histone methyltransferases (HMTs) and histone demethylase (HDMs), and histone deacetylases (HDACs).

Figure 2: Schematic drawing about chromatin remodeling of histone methylation and acetylating.

Targeting DNA Alteration for COPD Therapy

In COPD, DNA changes are observed by replacing cytidine within the DNA strain. Nucleoside analogs such as5-aza-2-deoxycytidine and 5-azacytidine act as DNMT inhibitors. Most of the substrate analogs are, modified by DNMTs analogs through covalent binding, which then inhibits the functioning of enzymes, resulting in hypomethylation of DNA. The PRC2 methylation binding sites are altered or reversed using azacitidine, resulting in (5-azacytidine) non-metastatic status [22].

Histone Modifications

Histone modifications were grouped into eight categories based on the type of amino acid and modified into methylation, methylation of arginine, acetylation of lysine, serine, ADP ribosylation, threonine phosphorylation, proline isomerization, arginine deamination, sumoylation, and ubiquitination [23,24]. The induction of a double-strand break at the DNA damage foci, histone acetylation, and methylation plays an essential role in the DNA damage response. Histone H3K9 and H3K56 acetylation and H3K4 and H3K36 trimethylation have been related to active gene transcription (euchromatin). In contrast, histone H3K9 and H3K27 tri-methylation have been linked to silence gene loci (heterochromatin) due to the closure of active chromatin in the gene [25-28].

Role of Histone Methylation in COPD

The modulation of histones is much more significant than DNA methylation. A recent mass spectrometry technique has identified possible novel histone marks in smoke-exposed mouse lungs, including acetylation, mono-methylation, and di-methylation of specific lysine and arginine residues of histones H3 and H4 [29]. Histone H3K27me2 and H3K27me1 were only found in the CS sensitivity community. These findings suggest that Polycomb plays a role in specific gene repression, particularly after smoking [29].

COPD Treatment Based on Histone Modifications

In patients with COPD, effective anti-inflammatory tested by treating with inhaled or systemic corticosteroids. However, even massive doses of corticosteroids showed an immune response in COPD patients. Impaired Histone Deacetylases (HDAC) function has recently been analyzed in-depth as one of the pathways contributing to corticosteroid tolerance. The activity of HATs was inhibited by activating Glucocorticoid Receptors (GR) which binds to the coactivators (Histone Acetyltransferase) [30,31]. Theophylline has been used for decades to treat airway conditions and was recently discovered as an activator of HDAC. In COPD patients alveolar macrophages, theophylline restores HDAC activity and steroid response [32]. In CS-exposed mice, a low dose of theophylline increased the anti-inflammatory effects of dexamethasone while also restoring HDAC2 movement [32]. The pharmacological activation by a small molecule activator, sulforaphane, of the antioxidant NRF2 can be a valuable technique for preventing and treating COPD and is currently being tested in patients with COPD in phase II clinical trials [33].

By deacetylating lysine residues that would or else be targeted for ubiquitin-mediated proteasomal degradation, functional HDAC2 is likely to inhibit NRF2 degradation [34]. In peripheral lung tissues and alveolar macrophages, HDAC2 activation was shown to be lower in patients with COPD when the enzyme was S-nitrosylated. Treatment with sulforaphane nitrosylated HDAC2 resulted in simultaneous activation of NRF2 and augmented intracellular glutathione levels in alveolar macrophages [35].

Conclusion

Dysregulation of DNA methylation in COPD-related genes, HDAC2 function, and miRNAs have all been shown to cause COPD disease in various studies. Inflammatory reactions are triggered by tobacco smoke and are a central factor in COPD development. It changes epigenetic operations such as gene expression by modifying DNA methylation, altering HDAC2 function by histone modifications, and dysregulation of COPD linked to mRNAs. Our review emphasizes the recent studies of specific techniques, such as Sirtuins, to control the activity of HDAC2 and have a therapeutic effect on COPD. The miRNAs have been shown to decrease COPD in more recent research. Finally, this review can address or help study a greater variety of issues in both diagnosis and treatment methods for COPD.

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