Search results for: minority carrier lifetime

Authors: Ksenija Milošević, Davor Lončarević, Tihana Mudrinić, Jasmina Dostanić

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Heterogeneous photocatalytic processes have gained growing interest as an efficient method to generate hydrogen by using clean energy sources and degrading various organic pollutants. The main obstacles that restrict efficient photoactivity are narrow light-response range and high rates of charge carrier recombination. The formation of heterojunction by combining a semiconductor with low VB and a semiconductor with high CB and a suitable band gap was found to be an efficient method to prepare more sensible materials with improved charge separation, appropriate oxidation and reduction ability, and enhanced visible-light harvesting. In our research, various binary heterojunction systems based on the wide-band gap (TiO₂) and narrow bandgap (g-C₃N₄, CuO, and Co₂O₃) photocatalyst were studied. The morphology, optical, and electrochemical properties of the photocatalysts were analyzed by X-ray diffraction (XRD), scanning electron microscopy (FE-SEM), N₂ physisorption, diffuse reflectance measurements (DRS), and Mott-Schottky analysis. The photocatalytic performance of the synthesized catalysts was tested in single and simultaneous systems. The synthesized photocatalysts displayed good adsorption capacity and enhanced visible-light photocatalytic performance. The mutual interactions of pollutants on their adsorption and degradation efficiency were investigated. The interfacial connection between photocatalyst constituents and the mechanism of the transport pathway of photogenerated charge species was discussed. A radical scavenger study revealed the interaction mechanisms of the photocatalyst constituents in single and multiple pollutant systems under solar and visible light irradiation, indicating the type of heterojunction system (Z scheme or type II).

Keywords: bandgap alignment, heterojunction, photocatalysis, reaction mechanism

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Authors: Samson Mil'shtein, Dhawal Asthana, Benjamin Sullivan

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The wide energy gap of GaN is the major parameter justifying the design and fabrication of high-power electronic components made of this material. However, the existence of a piezo-electrics in nature sheet charge at the AlGaN/GaN interface complicates the control of carrier injection into the intrinsic channel of GaN HEMTs (High Electron Mobility Transistors). As a result, most of the transistors created as R&D prototypes and all of the designs used for mass production are D-mode devices which introduce challenges in the design of integrated circuits. This research presents the design and modeling of an E-mode GaN HEMT with a very low turn-on voltage. The proposed device includes two critical elements allowing the transistor to achieve zero conductance across the channel when Vg = 0V. This is accomplished through the inclusion of an extremely thin, 2.5nm intrinsic Ga₀.₇₄Al₀.₂₆N spacer layer. The added spacer layer does not create piezoelectric strain but rather elastically follows the variations of the crystal structure of the adjacent GaN channel. The second important factor is the design of a gate metal with a high work function. The use of a metal gate with a work function (Ni in this research) greater than 5.3eV positioned on top of n-type doped (Nd=10¹⁷cm⁻³) Ga₀.₇₄Al₀.₂₆N creates the necessary built-in potential, which controls the injection of electrons into the intrinsic channel as the gate voltage is increased. The 5µm long transistor with a 0.18µm long gate and a channel width of 30µm operate at Vd=10V. At Vg =1V, the device reaches the maximum drain current of 0.6mA, which indicates a high current density. The presented device is operational at frequencies greater than 10GHz and exhibits a stable transconductance over the full range of operational gate voltages.

Keywords: compound semiconductors, device modeling, enhancement mode HEMT, gallium nitride

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Authors: Pankaj Pradhananga

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Inclusive Tourism is a relatively new topic in Nepal. Though the effort of creating accessible and inclusive tourism has already begun, it is still in its infancy. A major concern for Destination Nepal is the lack of awareness and absence of mandatory law in place to encourage Tourism operating sectors for coming up with accessible Tourism products. Given the number economic and social benefits to may be derived from inclusive tourism, it is a critical time for the tourism industry to understand and develop measures towards inclusivity in the gateway to Himalaya. Nepal was struck with a devastating earthquake on April 25th, 2015 which concurrently left more than 4,000 Nepalese with physical disabilities. Nepal has had to rebuild and is continuing to rebuild a lot of infrastructure and the process of rebuilding should be barrier free and use universal design measures. With universal design in place, this would allow access for minority groups such as people with disabilities and the elderly to the historic monuments in Kathmandu valley. Four Seasons Travel ( 4ST) has been a key player in not only creating accessible tourism experiences in Nepal, but also promoting accessible tourism to other tourism operators. Dr. Scott Rains had worked closely with 4ST on accessible tourism. Additionally, it organised an accessible trek which was field tested with a traveler with vision impairment in August 2015. Another accessible trekking experience, in partnership with Washington DC based International Development Institute, was coined as ‘Wounded Heroes Trek to Nepal’, where a group of Veterans that are amputees went trekking in the Annapurna Region. The event made it to the list of UNWTO World Tourism Day celebrations. Such initiatives led by private sector in partnership with various organizations have worked to create a ‘Destination Nepal for all’. However, there is still a lot of work that needs to be done to make Nepal a truly inclusive destination. Partnerships between the private sector and DPOs ( Disabled People’s Organizations) as well as the government are also a sound opportunity for employment creation for people with disabilities. Further, partnerships between the state, tourism service providers and DPOs need to be fostered to create job opportunities for people with disabilities. This can be exemplified through the social Entrepreneurship model with the help of accessible Tourism.

Keywords: accessible tourism, disability, earthquake, inclusion

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Authors: Shazia Anwer

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The current TV Talk Shows, especially on domestic politics in Pakistan are following the Aristotelian techniques, including deductive reasoning, three modes of persuasion, and guidelines for communication. The application of “Approximate Truth is also seen when Talk Show presenters create doubts against political personalities or national issues. Mainstream media of Pakistan, being a key carrier of narrative construction for the sake of the primary function of national consensus on regional and extended public diplomacy, is failing the purpose. This paper has highlighted the Aristotelian communication methodology, its purposes and its limitations for a serious discussion, and its connection to the mistrust among the Pakistani population regarding fake or embedded, funded Information. Data has been collected from 3 Pakistani TV Talk Shows and their analysis has been made by applying the Aristotelian communication method to highlight the core issues. Paper has also elaborated that current media education is impaired in providing transparent techniques to train the future journalist for a meaningful, thought-provoking discussion. For this reason, this paper has given an overview of HEC’s (Higher Education Commission) graduate-level Mass Com Syllabus for Pakistani Universities. The idea of ethos, logos, and pathos are the main components of TV Talk Shows and as a result, the educated audience is lacking trust in the mainstream media, which eventually generating feelings of distrust and betrayal in the society because productions look like the genre of Drama instead of facts and analysis thus the line between Current Affairs shows and Infotainment has become blurred. In the last section, practical implication to improve meaningfulness and transparency in the TV Talk shows has been suggested by replacing the Aristotelian communication method with the cognitive semiotic communication approach.

Keywords: Aristotelian techniques of communication, current affairs talk shows, drama, Pakistan

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Authors: Ezra N. S. Lockhart

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The number of children diagnosed with autism spectrum disorder (ASD) has increased approximately 173% during the last decade making ASD the fastest growing developmental disability in the United States. This rise in prevalence rates indeed has an effect on schools. ASD is overwhelmingly the most reported primary special education eligibility category for students accessing special education, at a national average of 61.3%. ASD is regarded as an urgent public health concern at an estimated annual per capita cost of $3.2 million. Furthermore, considering that ASD is a lifelong disorder estimated lifetime per capita cost reach $35 billion. The resources available to special education programs are insufficient to meet the educational needs of the 6.4 million students receiving special educational services. This is especially true given that there has been and continues to be a chronic shortage of fully certified special education teachers for decades. Reports indicate that 81.1% of students with special needs spend 40% or more in general education classrooms. Regardless of whether support is implemented in the special education or general education classroom the resource demand is obvious. Schools are actively seeking to implement low-cost alternatives and budget saving measures in response to this demand. In public school settings, programs such as Applied Behavior Analysis are challenging to implement and fund at $40,000 per student per year. As an alternative, computer-based interventions are inexpensive, less time-consuming to implement, and require minimal teacher or paraprofessional training to administer. Affordability, pricing schemes, availability, and compatibility of computer-based interventions that support social and emotional skill development in individuals with ASD are discussed.

Keywords: affordability, autism spectrum disorder, computer-based intervention, emotional skills, social skills

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Authors: N. V. Kazmiruk, Y. R. Nartsissov

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Phosphate activated glutaminase (GA, E.C. 3.5.1.2) plays a key role in glutamine/glutamate homeostasis in mammalian brain, catalyzing the hydrolytic deamidation of glutamine to glutamate and ammonium ions. GA is mainly localized in mitochondria, where it has the catalytically active form on the inner mitochondrial membrane (IMM) and the other soluble form, which is supposed to be dormant. At present time, the exact localization of the membrane glutaminase active site remains a controversial and an unresolved issue. The first hypothesis called c-side localization suggests that the catalytic site of GA faces the inter-membrane space and products of the deamidation reaction have immediate access to cytosolic metabolism. According to the alternative m-side localization hypothesis, GA orients to the matrix, making glutamate and ammonium available for the tricarboxylic acid cycle metabolism in mitochondria directly. In our study, we used a multi-compartment kinetic approach to simulate metabolism of glutamate and glutamine in the astrocytic cytosol and mitochondria. We used physiologically important ratio between the concentrations of glutamine inside the matrix of mitochondria [Glnₘᵢₜ] and glutamine in the cytosol [Glncyt] as a marker for precise functioning of the system. Since this ratio directly depends on the mitochondrial glutamine carrier (MGC) flow parameters, key observation was to investigate the dependence of the [Glnmit]/[Glncyt] ratio on the maximal velocity of MGC at different initial concentrations of mitochondrial glutamate. Another important task was to observe the similar dependence at different inhibition constants of the soluble GA. The simulation results confirmed the experimental c-side localization hypothesis, in which the glutaminase active site faces the outer surface of the IMM. Moreover, in the case of such localization of the enzyme, a 3-fold decrease in ammonium production was predicted.

Keywords: glutamate metabolism, glutaminase, kinetic approach, mitochondrial membrane, multi-compartment modeling

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Authors: Mary Allagoa, Abir Al-Tabbaa

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The study explores the use of binders and additives, such as Portland cement, pulverized fuel ash, ground granulated blast furnace slag, and MgO, to decrease the concentration and leachability of pollutants in contaminated site soils. The research investigates their effectiveness and associated risks of using the binders, with a focus on Total Heavy metals (THM) and Total Petroleum Hydrocarbon (TPH). The goal of this research is to evaluate the performance and effectiveness of binders and additives in remediating soil pollutants. The study aims to assess the suitability of the mixtures for ground improvement purposes, determine the optimal dosage, and investigate the associated risks. The research utilizes physical (unconfined compressive strength) and chemical tests (batch leachability test) to assess the efficacy of the binders and additives. A completely randomized design one-way ANOVA is used to determine the significance within mix binders of THM. The study also employs incremental lifetime cancer risk assessments (ILCR) and other indexes to evaluate the associated risks. The study finds that Ground Granulated Blast Furnace Slag (GGBS): MgO is the most effective binder for remediation, particularly when using low dosages of MgO combined with higher dosages of GGBS binders on TPH. The results indicate that binders and additives can encapsulate and immobilize pollutants, thereby reducing their leachability and toxicity. The mean unconfined compressive strength of the soil ranges from 285.0- 320.5 kPa, while THM levels are less than 10 µg/l in GGBS: MgO and CEM: PFA but below 1 µg/l in CEM I based. The ILCR ranged from 6.77E-02 - 2.65E-01 and 5.444E-01 – 3.20 E+00, with the highest values observed under extreme conditions. The hazard index (HI), Risk allowable daily dose intake (ADI), and Risk chronic daily intake (CDI) were all less than 1 for the THM. The study identifies MgO as the best additive for use in soil remediation.

Keywords: risk ADI, risk CDI, ILCR, novel binders, additives binders, hazard index

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Authors: Martina Dickson, Hanadi Kadbey, Melissa Mcminn

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Research has shown that anxiety and trepidation towards learning about science is prevalent among elementary school teachers in Western countries. It has also been shown repeatedly that pre-service and in-service teachers who show signs of anxiety towards science are; a) less likely to teach it at all, where they have some autonomy over this, b) less likely to teach it effectively c) ultimately that their students have lower attainment scores in science. It is therefore critically important to gauge pre-service teachers’ science anxiety levels early on whilst there are still possibilities to overturn some of the reasons behind these fears and avert these serious issues occurring later on. This study takes place in the capital of the United Arab Emirates (U.A.E.) in the context of training local elementary school teachers. In the U.A.E., where Emirati teachers are already in the vast minority and attrition rates are high, it is important to offer as much support to pre-service teachers as possible. If pre-service teachers are graduating with high levels of science anxiety unabated, according to the research there is a very real concern that as generalist primary school teachers, their science teaching will be far from optimal. The aims of this research study were to ascertain the science anxiety levels of pre-service elementary teachers and to identify particular areas of their science anxiety, if appropriate. We surveyed 200 Emirati pre-service teachers and found that levels of science anxiety were directly related to their perceptions of performance in science exams, laboratory experiments and inquiry approaches to science learning. Whilst some studies have shown that science anxiety can decrease as students gain confidence in science knowledge by studying courses, we did not see this effect in our study. This is based upon a theoretical framework which holds that in some cases, science anxiety is related to lack of exposure to, or insecurity with science content itself which in some cases is alleviated by the students’ covering of material and greater confidence in the subject. Exploring this variable allowed us to explore whether students educated in schools influenced by the educational reform in Abu Dhabi have differing science anxiety levels from those who were educated prior to the reforms. We discuss the possible implications of these findings to the future teaching of science in Abu Dhabi public schools.

Keywords: pre-service teachers, science anxiety, United Arab Emirates, educational reform

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Authors: Ipek Sensu

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Comorbid Axis I disorders are highly common for suicidal borderline personality disorder (BPD) patients, especially substance use disorder and anxiety disorders. Since interpersonal dysfunction is one of the core symptoms in BPD, the purpose of the current study is to examine perceived criticism and anxiety disorders and also substance abuse disorders (SUD) for women with borderline personality disorder (BPD) who attempt suicide at least once in their lifetime. In the current study, it was suggested that the perceived criticism from others and being upset by criticism differ between suicidal women with BPD with comorbidity of anxiety disorders and SUD (separately) and suicidal women with BPD without anxiety disorders and without SUD (separately). The participants in this study included ninety-nine women who have already been diagnosed with borderline personality disorder and also have had at least two episodes of deliberate self-harm, in other words, suicide attempts and/or non-suicidal self-injury (NSSI) in the last five years and at least one episode in the 8-week period before joining the research study and at least one suicide attempt in the previous year. Structured Clinical Interview for DSM-IV Axis I Disorders (SCID) and Social History Interview (SHI) were conducted to determine the comorbid axis I disorders and level of perceived criticism. As a result of the independent sample t-tests, the first hypothesis was rejected, in other words, women with BPD and a comorbid anxiety disorder did not show significantly higher levels of ‘criticized by others’, compared to women with BPD alone. However, the levels of ‘upset at criticism’ were significantly different between suicidal women with BPD with or without any anxiety disorders, which is the second hypothesis. In addition, the third hypothesis was also accepted; this means, women with BPD who had any substance use dependence would show significantly higher levels of 'criticized by others' compared to women with BPD alone. Finally, the fourth hypothesis was partly accepted: that is, women with BPD with alcohol dependence had significantly higher levels of ‘how upset when they expose to criticism’, compared to those without alcohol dependence. Limitations, implications, and directions for future research are discussed.

Keywords: anxiety disorders, borderline personality disorders, perceived criticism, substance use disorders

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Authors: Alexander Kospach, Fabian Benezeder, Jürgen Abraham

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E-mobility poses new challenges for inverters (e.g., higher switching frequencies) in terms of thermal behavior and thermal management. Due to even higher switching frequencies, thermal losses become greater, and the cooling of critical components (like insulated gate bipolar transistor and diodes) comes into focus. New manufacturing methods, such as 3D printing, enable completely new pin-fin structures that can handle higher waste heat to meet the new thermal requirements. Based on the geometrical specifications of the industrial partner regarding the manufacturing possibilities for 3D printing, different and completely new pin-fin structures were numerically investigated for their hydraulic and thermal behavior in fundamental studies assuming an indirect liquid cooling. For the 3D computational fluid dynamics (CFD) thermal simulations OpenFOAM was used, which has as numerical method the finite volume method for solving the conjugate heat transfer problem. A steady-state solver for turbulent fluid flow and solid heat conduction with conjugate heat transfer between solid and fluid regions was used for the simulations. In total, up to fifty pinfin structures and arrangements, some of them completely new, were numerically investigated. On the basis of the results of the principal investigations, the best two pin-fin structures and arrangements for the complete module cooling of an automotive inverter were numerically investigated and compared. There are clear differences in the maximum temperatures for the critical components, such as IGTBs and diodes. In summary, it was shown that 3D pin fin structures can significantly contribute to the improvement of heat transfer and cooling of an automotive inverter. This enables in the future smaller cooling designs and a better lifetime of automotive inverter modules. The new pin fin structures and arrangements can also be applied to other cooling applications where 3D printing can be used.

Keywords: pin fin heat sink optimization, 3D printed pin fins, CFD simulation, power electronic cooling, thermal management

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Authors: Wafula Simon Peter, Kimuli Nabayego Ibtihal, Nabaggala Kimuli Nashua

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The worldwide use of information and communications technology (ICT) equipment and other electronic equipment is growing and consequently, there is a growing amount of equipment that becomes waste after its time in use. This growth is expected to accelerate since equipment lifetime decreases with time and growing consumption. As a result, e-waste is one of the fastest-growing waste streams globally. The United Nations University (UNU) calculates in its second Global E-waste Monitor 44.7 million metric tonnes (Mt) of e-waste were generated globally in 2016. The study population was 80 respondents, from which a sample of 69 respondents was selected using simple and purposive sampling techniques. This research was carried out to investigate the problem of e-waste and come up with a framework to improve e-waste management. The objective of the study was to develop a framework for improving e-waste management at the College of Engineering, Design, Art and Technology (CEDAT). This was achieved by breaking it down into specific objectives, and these included the establishment of the policy and other Regulatory frameworks being used in e-waste management at CEDAT, the determination of the effectiveness of the e-waste management practices at CEDAT, the establishment of the critical challenges constraining e-waste management at the College, development of a framework for e-waste management. The study reviewed the e-waste regulatory framework used at the college and then collected data which was used to come up with a framework. The study also established that weak policy and regulatory framework, lack of proper infrastructure, improper disposal of e-waste and a general lack of awareness of the e-waste and the magnitude of the problem are the critical challenges of e-waste management. In conclusion, the policy and regulatory framework should be revised, localized and strengthened to contextually address the problem. Awareness campaigns, the development of proper infrastructure and extensive research to establish the volumes and magnitude of the problems will come in handy. The study recommends a framework for the improvement of e-waste.

Keywords: e-waste, treatment, disposal, computers, model, management policy and guidelines

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Authors: Lutendo Nendauni

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Colonialism breaks things, colonisers exploded native cultural solidarity, producing the spiritual confusion, psychic wounding, and economic exploitation of a new and dominated ‘other’. Colonialism as the cultural and economic exploitation began when the West defended in their seizure of foreign territories for the exploitation of its natural resources; this resulted in brutal socio-economic imbalances. The Western profited at the detriment of the weak Africa. However, colonialism has since passed, but the effects are still evident culturally, socially, and economically. This paper explored how postcolonial writers and critics attempt to reverse the socio-economic imbalances resulting from the fragmentation of colonialism, with a focus on the play 'I will Marry When I Want' by Ngugi wa Thiong’o and Ngugi wa Mirii, as a primary text. Using qualitative discourse-textual analysis as the research methodology, the researcher purposively extracts discourse segments from the text for analysis and interpretation. The findings reveal that Postcolonial critics and writers attempt to reverse the socio-economic effects of colonialism through various counter discourses; their literature is concerned with the destruction of colonised identity, the search for this identity, and its assertion. It is manifest in the text that writers offer corrective views about Africans; they stress that they write their literary texts to conscientise their fellow Africans. Postcolonial writers and critics argue that language is a carrier of culture and that the only way to break free from colonial influence is by not adopting a foreign language. They further through their poems, novels, plays, and music strategically shine the spotlight on the previously nameless and destitute people so that they can develop the human spirit’s desire to overcome defeat, socio-political deprivation, and isolation.

Keywords: colonialism, postcoloniality, critics, socio-economic imbalances

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Authors: H. F. Shi, C. L. Zhang

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Visible-light-responsive g-C3N4/NaNbO3 nanowires photocatalysts were fabricated by introducing polymeric g-C3N4 on NaNbO3 nanowires. The microscopic mechanisms of interface interaction, charge transfer and separation, as well as the influence on the photocatalytic activity of g-C3N4/NaNbO3 composite were systematic investigated. The HR-TEM revealed that an intimate interface between C3N4 and NaNbO3 nanowires formed in the g-C3N4/NaNbO3 heterojunctions. The photocatalytic performance of photocatalysts was evaluated for CO2 reduction under visible-light illumination. Significantly, the activity of g-C3N4/NaNbO3 composite photocatalyst for photoreduction of CO2 was higher than that of either single-phase g-C3N4 or NaNbO3. Such a remarkable enhancement of photocatalytic activity was mainly ascribed to the improved separation and transfer of photogenerated electron-hole pairs at the intimate interface of g-C3N4/NaNbO3 heterojunctions, which originated from the well-aligned overlapping band structures of C3N4 and NaNbO3. Pt loaded NaNbO3-xNx (Pt-NNON), a visible-light-sensitive photocatalyst, was synthesized by an in situ photodeposition method from H2PtCl6•6H2O onto NaNbO3-xNx (NNON) sample. Pt-NNON exhibited a much higher photocatalytic activity for gaseous 2-propanol (IPA) degradation under visible-light irradiation in contrast to NNON. The apparent quantum efficiency (AQE) of Pt-NNON sample for IPA photodegradation achieved up to 8.6% at the wavelength of 419 nm. The notably enhanced photocatalytic performance was attributed to the promoted charge separation and transfer capability in the Pt-NNON system. This work suggests that surface nanosteps possibly play an important role as an electron transfer at high way, which facilitates to the charge carrier collection onto Pt rich zones and thus suppresses recombination between photogenerated electrons and holes. This method can thus be considered as an excellent strategy to enhance photocatalytic activity of organic decomposition in addition to the commonly applied noble metal doping method.

Keywords: CO2 reduction, NaNbO3, nanowires, g-C3N4

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Authors: Aita Bishowkarma

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Ensuring quality education in primary level in multi-ethnic, multi- religious, multi-cultural and multilingual country Nepal which accommodates 123 ethnic languages (CBS 2011) has come across a big challenge. The discourse on the policies and practices to take advantage of the rich heritage of cultural and linguistic diversity in the pursuit of quality primary education to ethnic/linguistic minority children in Nepal gives in a critical observation of Nepalese perspective in the global academia. Situating the linguistic diversity of Nepal, primary education to children is better through mother tongue. Nepali as official or national language is another important language to be taught to the children. Similarly, craze for English has been inevitable for international communication and job opportunity in the global markets. This paper critically examines the current use of trilingual policy in mother tongue based multilingual education (MT-MLE) in Nepal from the perspective of exploiting linguistic diversity in classroom pedagogy. The researcher adopted mixed method research design applying descriptive measure and explanatory research methods. 24 teachers and 48 students from 6 multilingual schools were selected purposively to dig out their language use, language attitude and language preferences to reveal their preference and attitude towards mother tongue, Nepali and English through questionnaire, interview and focus group discussion. The study shows, in a true multilingual system, all languages (mother tongue, languages of region, nation and wider communication) can have their legitimate place; bridging from the mother tongue to the regional language and national to international language; further leading to meaningful participation in the wider democratic global context. Trilingual policy of mother tongue, national language and international language seemed pertinent however, not sufficient. The finding of the study shows that for quality education in primary education mother tongue based critical multilingual pedagogy through language coexistence approach with contextual variation seems enviable.

Keywords: critical pedagogy, language co-existence, linguistic diversity, quality education

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Authors: Maria C. Proença, Maria T. Rebelo, Maria J. Alves, Sofia Cunha

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Vector-borne diseases are transmitted to humans by mosquitos, sandflies, bugs, ticks, and other vectors. Some are re-transmitted between vectors, if the infected human has a new contact when his levels of infection are high. The vector is infected for lifetime and can transmit infectious diseases not only between humans but also from animals to humans. Some vector borne diseases are very disabling and globally account for more than one million deaths worldwide. The mosquitoes from the complex Culex pipiens sl. are the most abundant in Portugal, and we dispose in this moment of a data set from the surveillance program that has been carried on since 2006 across the country. All mosquitos’ species are included, but the large coverage of Culex pipiens sl. and its importance for public health make this vector an interesting candidate to assess risk of disease amplification. This work focus on ports and airports identified as key areas of high density of vectors. Mosquitoes being ectothermic organisms, the main factor for vector survival and pathogen development is temperature. Minima and maxima local air temperatures for each area of interest are averaged by month from data gathered on a daily basis at the national network of meteorological stations, and interpolated in a geographic information system (GIS). The range of temperatures ideal for several pathogens are known and this work shows how to use it with the meteorological data in each port and airport facility, to focus an efficient implementation of countermeasures and reduce simultaneously risk transmission and mitigation costs. The results show an increased alert with decreasing latitude, which corresponds to higher minimum and maximum temperatures and a lower amplitude range of the daily temperature.

Keywords: human health, risk assessment, risk management, vector-borne diseases

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Authors: Farahnaz Karami

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Routing is an important, challenging task in mobile ad hoc networks due to node mobility, lack of central control, unstable links, and limited resources. An ant colony has been found to be an attractive technique for routing in Mobile Ad Hoc Networks (MANETs). However, existing swarm intelligence based routing protocols find an optimal path by considering only one or two route selection metrics without considering correlations among such parameters making them unsuitable lonely for routing real time applications. Fuzzy logic combines multiple route selection parameters containing uncertain information or imprecise data in nature, but does not have multipath routing property naturally in order to provide load balancing. The objective of this paper is to design a routing algorithm using fuzzy logic and ant colony that can solve some of routing problems in mobile ad hoc networks, such as nodes energy consumption optimization to increase network lifetime, link failures rate reduction to increase packet delivery reliability and providing load balancing to optimize available bandwidth. In proposed algorithm, the path information will be given to fuzzy inference system by ants. Based on the available path information and considering the parameters required for quality of service (QoS), the fuzzy cost of each path is calculated and the optimal paths will be selected. NS2.35 simulation tools are used for simulation and the results are compared and evaluated with the newest QoS based algorithms in MANETs according to packet delivery ratio, end-to-end delay and routing overhead ratio criterions. The simulation results show significant improvement in the performance of these networks in terms of decreasing end-to-end delay, and routing overhead ratio, and also increasing packet delivery ratio.

Keywords: mobile ad hoc networks, routing, quality of service, ant colony, fuzzy logic

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Authors: Rajesh Agarwal

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Carrier mobility at the organic/insulator interface is essential to the performance of organic thin film transistors (OTFT). The present work describes estimation of field dependent mobility (FDM) parameters and the threshold voltage of an OTFT using a simple, easy to fabricate two terminal asymmetric capacitive test structure using admittance measurements. Conventionally, transfer characteristics are used to estimate the threshold voltage in an OTFT with field independent mobility (FIDM). Yet, this technique breaks down to give accurate results for devices with high contact resistance and having field dependent mobility. In this work, a new technique is presented for characterization of long channel organic capacitor (LCOC). The proposed technique helps in the accurate estimation of mobility enhancement factor (γ), the threshold voltage (V_th) and band mobility (µ₀) using capacitance-voltage (C-V) measurement in OTFT. This technique also helps to get rid of making short channel OTFT or metal-insulator-metal (MIM) structures for making C-V measurements. To understand the behavior of devices and ease of analysis, transmission line compact model is developed. The 2-D numerical simulation was carried out to illustrate the correctness of the model. Results show that proposed technique estimates device parameters accurately even in the presence of contact resistance and field dependent mobility. Pentacene/Poly (4-vinyl phenol) based top contact bottom-gate OTFT’s are fabricated to illustrate the operation and advantages of the proposed technique. Small signal of frequency varying from 1 kHz to 5 kHz and gate potential ranging from +40 V to -40 V have been applied to the devices for measurement.

Keywords: capacitance, mobility, organic, thin film transistor

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Authors: Barnali Saha

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Dalit writing is the interventionalist voice of the dispossessed subaltern in the cultural economy of the society. As such, Dalit writing, including Dalit poetry, considers the contradictions that permeate the socio-cultural structure historically allocated and religiously sanctioned in the Indian subcontinent. As an epicenter of all Dalit experiences of trauma and violence, the poetics the Dalit body is deeply rooted in the peripheral space socially assigned to it by anachronistic caste-based litigation. An appraisal of Dalit creative-critical work by writers like Sharan Kumar Limbale, Arjun Dangle, Namdeo Dhasal, Om Prakash Valmiki, Muktibodh and others underscore the conjunction of the physical, psychical and the psychological in their interpretation of Dalit consciousness. They put forward the idea that Dalit poetry is begotten by the trauma of societal oppression and therefore, Dalit language and its revitalization are two elements obdurately linked to Dalit poetics. The present research paper seeks to read the problematization of the Dalit agency through the conduit of the Dalit voice wherein the anatomical category of the mouth is closely related to the question of Dalit identity. Theoretically aligned to Heidegger’s notion of language as the house of being and Bachelard’s assertion of a house as an ideal metaphor of poetic imagination and Dylan Trigg’s view of the coeval existence of space and body, the paper examines a series of selected poems by Dalit poetic voices to examine how their distinct Dalit point of view underscores Dalit speech and directs our attention to the historical abstraction of it. The paper further examines how speech as a category in Dalit writing places the Dalit somatic entity as a site of contestation with the ‘Mouth’ as a loaded symbolic category inspiring rebellion and resistance. And as the quintessential purpose of Dalit literature is the unleashing of Dalit voice from the anti-verbal domain of social decrepitude, Dalit poetry needs to be critically read based on the experience of the mouth and the patois.

Keywords: Dalit, poetry, speech, mouth, subaltern, minority, exploitation, space

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Authors: Emily S. M. Chow

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The word ‘utopia’ was coined by Thomas More in Utopia (1516). Its Greek roots ‘ou’ means ‘not’ and ‘topos’ means ‘place.’ In other words, it literally refers to ‘no-place.’ However, the possibility of having an alternative and better future society has always been appealing. In fact, at the core of every utopianism is the search for a future alternative state with the anticipation of a better life. Nonetheless, the practicalities of such ideas have never ceased to be questioned. At times, building a utopia presents itself as a divisive act. In addition to the violence that must be employed to sweep away the old regime in order to make space for the new, all utopias carry within them the potential for bringing catastrophic consequences to human life. After all, every utopia seeks to remodel the individual in a very particular way for the benefit of the masses. In this sense, utopian thinking has the potential both to create and destroy the future. While writing during a traumatic transitional period in Zimbabwe’s history, Dambudzo Marechera witnessed an age of upheavals in which different parties battled for power over Zimbabwe. Being aware of the fact that all institutionalized narratives, be they originated from the governance of the UK, Ian Smith’s white minority regime or Zimbabwe’s revolutionary parties, revealed themselves to be nothing more than fiction, Marechera realized the impossibility of determining reality absolutely. As such, this thesis concerns the writing of the Zimbabwean maverick, Dambudzo Marechera. It argues that Marechera writes a unique vision of utopia. In short, for Marechera utopia is not a static entity but a moment of perpetual change. He rethinks utopia in the sense that he phrases it as an event that ceaselessly contests institutionalized and naturalized narratives of a post-colonial self and its relationship to society. Marechera writes towards a vision of an alternative future of the country. Yet, it is a vision that does not constitute a fully rounded sense of utopia. Being cautious about the world and the operation of power upon the people, rather than imposing his own utopian ideals, Marechera chooses to instead peeling away the narrative constitution of the self in relation to society in order to turn towards a truly radical utopian thinking that empowers the individual.

Keywords: African literature, Marechera, post-colonial literature, utopian studies

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Authors: Kwok W. Mui, Ling T. Wong, Tsz W. Tsang

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Many Hong Kong people nowadays spend most of their lifetime working indoor. Since poor Indoor Air Quality (IAQ) potentially leads to discomfort, ill health, low productivity and even absenteeism in workplaces, a call for establishing statutory IAQ control to safeguard the well-being of residents is urgently required. Although policies, strategies, and guidelines for workplace IAQ diagnosis have been developed elsewhere and followed with remedial works, some of those workplaces or buildings have relatively late stage of the IAQ problems when the investigation or remedial work started. Screening for IAQ problems should be initiated as it will provide information as a minimum provision of IAQ baseline requisite to the resolution of the problems. It is not practical to sample all air pollutants that exit. Nevertheless, as a statutory control, reliable, rapid screening is essential in accordance with a compromise strategy, which balances costs against detection of key pollutants. This study investigates the feasibility of using an IAQ index as a parameter of IAQ control in Hong Kong. The index is a screening parameter to identify the unsatisfactory workplace IAQ and will highlight where a fully effective IAQ monitoring and assessment is needed for an intensive diagnosis. There already exist a number of representative common indoor pollutants based on some extensive IAQ assessments. The selection of pollutants is surrogate to IAQ control consists of dilution, mitigation, and emission control. The IAQ Index and assessment will look at high fractional quantities of these common measurement parameters. With the support of the existing comprehensive regional IAQ database and the IAQ Index by the research team as the pre-assessment probability, and the unsatisfactory IAQ prevalence as the post-assessment probability from this study, thresholds of maintaining the current measures and performing a further IAQ test or IAQ remedial measures will be proposed. With justified resources, the proposed IAQ Index and assessment protocol might be a useful tool for setting up a practical public IAQ surveillance programme and policy in Hong Kong.

Keywords: assessment, index, indoor air quality, surveillance programme

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Authors: Torben Hansen

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While trust has long been regarded as one of the most critical variables for developing and maintaining well-functioning financial customer-seller relationships it can be suggested that trust not only relates to customer trust in individual companies (narrow-scope trust). Trust also relates to the broader business context in which consumers may carry out their financial behaviour (broad-scope trust). However, despite the well-recognized significance of trust in marketing research, only few studies have investigated the role of broad-scope trust in consumer financial behaviour. Moreover, as one of its many serious outcomes, the global financial crisis has elevated the need for an improved understanding of the role of broad-scope trust in consumer financial services markets. Only a minority of US and European consumers are currently confident in financial companies and ‘financial stability’ and ‘trust’ are now among the top reasons for choosing a bank. This research seeks to address this shortcoming in the marketing literature by investigating direct and moderating effects of broad-scope trust on consumer financial behaviour. Specifically, we take an ability-effort approach to consumer financial behaviour. The ability-effort approach holds the basic premise that the quality of consumer actions is influenced by ability factors, for example consumer knowledge and cognitive effort. Our study is based on two surveys. Survey 1 comprises 1,155 bank consumers, whereas survey 2 comprises 764 pension consumers. The results indicate that broad-scope trust negatively moderates relationships between knowledge and financial healthiness and between cognitive effort and financial healthiness. In addition, it is demonstrated that broad-scope trust negatively influences cognitive effort. Specifically, the results suggest that broad-scope trust contributes to the financial well-being of consumers with limited financial knowledge and processing capabilities. Since financial companies are dependent on customers to pay their loans and bills they have a greater interest in developing relations with consumers with a healthy financial behaviour than with the opposite. Hence, financial managers should be engaged with monitoring and influencing broad-scope trust. To conclude, by taking into account the contextual effect of broad-scope trust, the present study adds to our understanding of knowledge-effort-behaviour relationship in consumer financial markets.

Keywords: cognitive effort, customer-seller relationships, financial healthiness, knowledge, trust

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Authors: Berkas Khaoula

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Based on selection characteristics, high-density polyethylene (HDPE) extruded pipes are among the most economical and durable materials as well-designed solutions for water and gas transmission systems. The main reasons for such a choice are the high quality-performance ratio and the long-term service durability under aggressive conditions. Due to inevitable interactions with soils of different chemical compositions and transported fluids, aggressiveness becomes a key factor in studying resilient strength and life prediction limits. This phenomenon is known as environmental stress cracking resistance (ESCR). In this work, the effect of 3 acidic environments (5% acetic, 20% hydrochloric and 20% sulfuric) on HDPE-100 samples (~10x11x24 mm3). The results presented in the form (Δm/m0, %) as a function of √t indicate that the absorption, in the case of strong acids (HCl and H2SO4), evolves towards negative values involving material losses such as antioxidants and some additives. On the other hand, acetic acid and deionized water (DW) give a form of linear Fickean (LF) and B types, respectively. In general, the acids cause a slow but irreversible alteration of the chemical structure, composition and physical integrity of the polymer. The DW absorption is not significant (~0.02%) for an immersion duration of 69 days. Such results are well accepted in actual applications, while changes caused by acidic environments are serious and must be subjected to particular monitoring of the OIT factor (Oxidation Induction Time). After 55 days of aging, the H2SO4 and HCl media showed particular values with a loss of % mass in the interval [0.025-0.038] associated with irreversible chemical reactions as well as physical degradations. This state is usually explained by hydrolysis of the polymer, causing the loss of functions and causing chain scissions. These results are useful for designing and estimating the lifetime of the tube in service and in contact with adverse environments.

Keywords: HDPE, environmental stress cracking, absorption, acid media, chemical aging

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Authors: Ergin Kosa, Ali Göksenli

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Erosion and abrasion are wear mechanisms reducing the lifetime of machine elements like valves, pump and pipe systems. Both wear mechanisms are acting at the same time, causing a “Synergy” effect, which leads to a rapid damage of the surface. Different parameters are effective on erosive abrasive wear rate. In this study effect of particle impact angle on wear rate and wear mechanism of ductile and brittle materials was investigated. A new slurry pot was designed for experimental investigation. As abrasive particle, silica sand was used. Particle size was ranking between 200-500 µm. All tests were carried out in a sand-water mixture of 20% concentration for four hours. Impact velocities of the particles were 4,76 m/s. As ductile material steel St 37 with Brinell Hardness Number (BHN) of 245 and quenched St 37 with 510 BHN was used as brittle material. After wear tests, morphology of the eroded surfaces were investigated for better understanding of the wear mechanisms acting at different impact angles by using optical microscopy and Scanning Electron Microscope. The results indicated that wear rate of ductile material was higher than brittle material. Maximum wear was observed by ductile material at a particle impact angle of 300. On the contrary wear rate increased by brittle materials by an increase in impact angle and reached maximum value at 450. High amount of craters were detected after observation on ductile material surface Also plastic deformation zones were detected, which are typical failure modes for ductile materials. Craters formed by particles were deeper according to brittle material worn surface. Amount of craters decreased on brittle material surface. Microcracks around craters were detected which are typical failure modes of brittle materials. Deformation wear was the dominant wear mechanism on brittle material. At the end it is concluded that wear rate could not be directly related to impact angle of the hard particle due to the different responses of ductile and brittle materials.

Keywords: erosive wear, particle impact angle, silica sand, wear rate, ductile-brittle material

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Authors: Snezana Lazic, Zarko Gacevic, Mark Holmes, Ekaterina Chernysheva, Marcus Müller, Peter Veit, Frank Bertram, Juergen Christen, Yasuhiko Arakawa, Enrique Calleja

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The study reports how the pencil-like morphology of a homoepitaxially grown GaN nanowire can be exploited for the fabrication of a thin conformal InGaN nanoshell, hosting nonpolar, semipolar and polar single photon sources (SPSs). All three SPS types exhibit narrow emission lines (FWHM~0.35 - 2 meV) and high degrees of linear optical polarization (P > 70%) in the low-temperature micro-photoluminescence (µ-PL) experiments and are characterized by a pronounced antibunching in the photon correlation measurements (gcorrected(2)(0) < 0.3). The quantum-dot-like exciton localization centers induced by compositional fluctuations within the InGaN nanoshell are identified as the driving mechanism for the single photon emission. As confirmed by the low-temperature transmission electron microscopy combined with cathodoluminescence (TEM-CL) study, the crystal region (i.e. non-polar m-, semi-polar r- and polar c-facets) hosting the single photon emitters strongly affects their emission wavelength, which ranges from ultra-violet for the non-polar to visible for the polar SPSs. The photon emission lifetime is also found to be facet-dependent and varies from sub-nanosecond time scales for the non- and semi-polar SPSs to a few nanoseconds for the polar ones. These differences are mainly attributed to facet-dependent indium content and electric field distribution across the hosting InGaN nanoshell. The hereby reported pencil-like InGaN nanoshell is the first single nanostructure able to host all three types of single photon emitters and is thus a promising building block for tunable quantum light devices integrated into future photonic and optoelectronic circuits.

Keywords: GaN nanowire, InGaN nanoshell, linear polarization, nonpolar, semipolar, polar quantum dots, single-photon sources

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Authors: Syed Sibtain Hussain Shah

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The Afghan Taliban returned to power corridors in Afghanistan in August 2021 after waging a twenty-year insurgency in the country. U.S.-led forces completed their withdrawal from Afghanistan on August 30, 2021, but the Taliban took control of the whole country till August 15, 2021. At the same time, some of the militant groups such as Tehrik-e-Taliban Pakistan (TTP) and Islamic State Khurasan (IS-K) reappeared in Pakistan’s borders and other areas and by increasing attacks on the armed forces of Pakistan and minorities communities. These groups once again created a crucial challenge to the internal security of the country. Since mid of 2021, many of the terrorist incidents in the countries specified in the areas of Pakistan bordering Afghanistan were committed by TTP and IS-K. The aim of this paper is to investigate the reappearance of TTP and IS-K in 2021 and 2022 as a crucial threat to the internal security of Pakistan. The author will particularly probe threats to the security of military personnel and their installations and threats to human security, including danger to religious minority communities in the different areas of the country, including border areas such as Waziristan, which was once a hub of TTP and other militant groups in the 2000s. The author will employ the relevant method and appropriate theories of security studies, such as religious extremism and terrorism, in this study. TTP, inspired by the Afghan Taliban, initially emerged in Pakistan in 2007 and this group has so far targeted various religious and ethnic communities and government installations in Pakistan. The group is not only against Pakistan’s government policies, but it also committed terrorist attacks on the communities of the other Muslim sects and as well as non-Muslim communities. Most of the prominent figures of this violent group disappeared or escaped to Afghanistan after military actions, such as the larger “Zarb-e-Azb” operation in Pakistan in 2015. IS-K, which established its branch of Khurasan covering Pakistan and Afghanistan in 2015, with its main formation in Iraq and Syria in 2015, by targeting religious minorities such as Shia Muslims, has so far created a vital security challenge for the security of the country.

Keywords: Pakistan, Afghanistan, Afghan Taliban, Pakistani Taliban, Islamic state Khorasan, security threat

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Authors: Xiaoting Jing, Ling Huang

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After the reform and opening up, Chongqing has formed far more high-rise residential areas than other cities in its more than 40 years of urban construction. High-rise residential areas have become one of the main modern living models in Chongqing and an important carrier reflecting the city's high quality of life. Reviewing the construction process and renewal work helps understand the characteristics of high-rise residential areas in Chongqing at different stages, clarify current development demands, and look forward to the focus of future renewal work. Based on socio-economic development and policy background, the article sorts the construction process of high-rise residential areas in Chongqing into four stages: the early experimental construction period of high-rise residential areas (1978-1996), the rapid start-up period of high-rise commodity housing construction (1997-2006), the large-scale construction period of high-rise commodity housing and public rental housing (2007-2014), and the period of renewal and renovation of high-rise residential areas and step-by-step construction of quality commodity housing (2015-present). Based on the construction demands and main construction types of each stage, the article summarizes that the construction of high-rise residential areas in Chongqing features large scale, high speed, and high density. It points out that a large number of high-rise residential areas built after 2000 will become important objects of renewal and renovation in the future. Based on existing renewal work experience, it is urgent to explore a path for sustainable renewal and development in terms of policy mechanisms, digital supervision, and renewal and renovation models, leading the high-rise living in Chongqing toward high-quality development.

Keywords: high-rise residential areas, construction process, renewal and renovation, Chongqing

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Authors: Karen Butler

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The LGBTQ youth of color face stigma related to both race and gender identity. Effectively dealing with racial/ethnic discrimination requires strong connections to family and one’s racial/ethnic group. However, LGBTQ youth of color seldom receive support from family, peer groups or church groups. Moreover, ethnic communities often perceive LGBTQ identities as a rejection of ethnic heritage. Thus, stigma places these young people at greater risk for substance use, violence, risky sexual behaviors, suicide, and homelessness. Offering a Queer Studies (QS) class is one way to facilitate a safer and more inclusive environment for LGBTQ students, faculty and staff. The discipline of Queer Studies encompasses theories and thinkers from numerous fields: cultural studies, gay and lesbian studies, race studies, women's studies, media, postmodernism, post-colonialism, psychoanalysis and more. We began our course development by researching existing programs and classes. Several course syllabi were examined and course materials such as readings, videos, and guest speakers were assessed for possible inclusion. We also employed informal survey methods with students and faculty in order to gauge interest in the course. We then developed a sample course syllabus and began the process of new course approval. Feedback thus far indicates that students of various sexual orientations and gender identities are interested in the course and understand the need to offer it; faculty in Psychology, Social Work, and Interdisciplinary Studies are interested in cross-listing the course; library staff is willing to assist with course material acquisition, and the administration is supportive. The purpose of this session is to 1) explore the various health and wellness issues facing LGBTQ students of color and 2) share our experience of developing a QS course in health education in order to address these needs. This process, from initial recognition of the need to a course offering, will be described and discussed in the hopes that participants will increase their awareness of the issues. A QS course would be an appropriate requirement for any number of majors as well as an elective for any major.

Keywords: black colleges, health education, LGBTQ, queer studies

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Authors: Renjith George, Preethy Mary Donald

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Use of internet sources to retrieve health care related information among health care professionals has increased tremendously as the accessibility to internet is made easier through smart phones and tablets. Though there are huge data available at a finger touch, it is doubtful whether all the sources providing health care information adhere to evidence based practice. The objective of this survey was to study the prevalence of use of internet sources to get health care information, to assess the mind-set towards the authenticity of health care information available via internet sources and to study the awareness about evidence based practice in health care among medical and dental students in Melaka-Manipal Medical College. The survey was proposed as there is limited number of studies reported in the literature and this is the first of its kind in Malaysia. A cross sectional survey was conducted among the medical and dental students of Melaka-Manipal Medical College. A total of 521 students including medical and dental students in their clinical years of undergraduate study participated in the survey. A questionnaire consisting of 14 questions were constructed based on data available from the published literature and focused group discussion and was pre-tested for validation. Data analysis was done using SPSS. The statistical analysis of the results of the survey proved that the use of internet resources for health care information are equally preferred over the conventional resources among health care students. Though majority of the participants verify the authenticity of information from internet sources, there was considerable percentage of candidates who feels that all the information from the internet can be utilised for clinical decision making or were not aware about the need of verification of authenticity of such information. 63.7 % of the participants rely on evidence based practice in health care for clinical decision making while 34.2 % were not aware about it. A minority of 2.1% did not agree with the concept of evidence based practice. The observations of the survey reveals the increasing use of internet resources for health care information among health care students. The results warrants the need to move towards evidence based practice in health care as all health care information available online may not be reliable. The health care person should be judicious while utilising the information from such resources for clinical decision making.

Keywords: authenticity, evidence based practice, health care information, internet

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Authors: Yanhua Zhao, Yu Gou, Shu Feng, Dongdong Li, Chuanmin Tao

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The natural history of HBV infection could experience immune tolerant (IT), immune clearance (IC), HBeAg-negative inactive/quienscent carrier (ENQ), and HBeAg-negative hepatitis (ENH). As current biomarkers for discriminating these four phases have some weaknesses, additional serological indicators are needed. Hepatits B core-related antigen (HBcrAg) encoded with precore/core gene contains denatured HBeAg, HBV core antigen (HBcAg) and a 22KDa precore protein (p22cr), which was demonstrated to have a close association with natural history of hepatitis B infection, but no specific cutoff values and diagnostic parameters to evaluate the diagnostic efficacy. This study aimed to clarify the distribution of HBcrAg levels and evaluate its diagnostic performance during the natural history of infection from a Western Chinese perspective. 294 samples collected from treatment-naïve chronic hepatitis B (CHB) patients in different phases (IT=64; IC=72; ENQ=100, and ENH=58). We detected the HBcrAg values and analyzed the relationship between HBcrAg and HBV DNA. HBsAg and other clinical parameters were quantitatively tested. HBcrAg levels of four phases were 9.30 log U/mL, 8.80 log U/mL, 3.00 log U/mL, and 5.10 logU/mL, respectively (p < 0.0001). Receiver operating characteristic curve analysis demonstrated that the area under curves (AUCs) of HBcrAg and quantitative HBsAg at cutoff values of 9.25 log U/mL and 4.355 log IU/mL for distinguishing IT from IC phases were 0.704 and 0.694, with sensitivity 76.39% and 59.72%, specificity 53.13% and 79.69%, respectively. AUCs of HBcrAg and quantitative HBsAg at cutoff values of 4.15 log U/mlmL and 2.395 log IU/mlmL for discriminating between ENQ and ENH phases were 0.931 and 0.653, with sensitivity 87.93% and 84%, specificity 91.38% and 39%, respectively. Therefore, HBcrAg levels varied significantly among four natural phases of HBV infection. It had higher predictive performance than quantitative HBsAg for distinguishing between ENQ-patients and ENH-patients and similar performance with HBsAg for the discrimination between IT and IC phases, which indicated that HBcrAg could be a potential serological marker for CHB.

Keywords: chronic hepatitis B, hepatitis B core-related antigen, hepatitis B surface antigens, hepatitis B virus

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Authors: Benbelkacem Ouerdia

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Heterotrophic denitrification has been proven to be one of the most feasible processes for removing nitrate from wastewater and drinking water. In this process, heterotrophic bacteria use organic carbon for both growth and as an electron source. Underground water pollution by nitrates become alarming in Algeria. A survey carried out revealed that the nitrate concentration is in continual increase. Studies in some region revealed contamination exceeding the recommended permissible dose which is 50 mg/L. Worrying values in the regions of Mascara, Ouled saber, El Eulma, Bouira and Algiers are respectively 72 mg/L, 75 mg/L, 97 mg/L, 102 mg/L, and 158 mg/L. High concentration of nitrate in drinking water is associated with serious health risks. Research on nitrate removal technologies from municipal water supplies is increasing because of nitrate contamination. Biological denitrification enables the transformation of oxidized nitrogen compounds by a wide spectrum of heterotrophic bacteria into harmless nitrogen gas with accompanying carbon removal. Globally, denitrification is commonly employed in biological nitrogen removal processes to enhance water quality The study investigated the valorization of a vegetable residue as a carbon source (dates nodes) in water treatment using the denitrification process. Throughout the study, the effect of inoculums addition, pH, and initial concentration of nitrates was also investigated. In this research, a natural organic substance: dates nodes were investigated as a carbon source in the biological denitrification of drinking water. This material acts as a solid substrate and bio-film carrier. The experiments were carried out in batch processes. Complete denitrification was achieved varied between 80 and 100% according to the type of process used. It was found that the nitrate removal rate based on our results, we concluded that the removal of organic matter and nitrogen compounds depended mainly on the initial concentration of nitrate. The effluent pH was mainly affected by the C/N ratio, where a decrease increases pH.

Keywords: biofilm, carbon source, dates nodes, heterotrophic denitrification, nitrate, nitrite

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