Search results for: behaviour modifiers
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 1932

Search results for: behaviour modifiers

1452 Investigation of the Properties of Epoxy Modified Binders Based on Epoxy Oligomer with Improved Deformation and Strength Properties

Authors: Hlaing Zaw Oo, N. Kostromina, V. Osipchik, T. Kravchenko, K. Yakovleva

Abstract:

The process of modification of ed-20 epoxy resin synthesized by vinyl-containing compounds is considered. It is shown that the introduction of vinyl-containing compounds into the composition based on epoxy resin ED-20 allows adjusting the technological and operational characteristics of the binder. For improvement of the properties of epoxy resin, following modifiers were selected: polyvinylformalethyl, polyvinyl butyral and composition of linear and aromatic amines (Аramine) as a hardener. Now the big range of hardeners of epoxy resins exists that allows varying technological properties of compositions, and also thermophysical and strength indicators. The nature of the aramin type hardener has a significant impact on the spatial parameters of the mesh, glass transition temperature, and strength characteristics. Epoxy composite materials based on ED-20 modified with polyvinyl butyral were obtained and investigated. It is shown that the composition of resins based on derivatives of polyvinyl butyral and ED-20 allows obtaining composite materials with a higher complex of deformation-strength, adhesion and thermal properties, better water resistance, frost resistance, chemical resistance, and impact strength. The magnitude of the effect depends on the chemical structure, temperature and curing time. In the area of concentrations, where the effect of composite synergy is appearing, the values of strength and stiffness significantly exceed the similar parameters of the individual components of the mixture. The polymer-polymer compositions form their class of materials with diverse specific properties that ensure their competitive application. Coatings with high performance under cyclic loading have been obtained based on epoxy oligomers modified with vinyl-containing compounds.

Keywords: epoxy resins, modification, vinyl-containing compounds, deformation, strength properties

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1451 Assessment of Work Postures and Prevalence of Musculoskeletal Disorders among Diamond Polishers in Botswana: A Case Study

Authors: Oanthata Jester Sealetsa, Richie Moalosi

Abstract:

Musculoskeletal Disorders (MSDs) are reported to be amongst the leading contributing factors of low productivity in many industries across the world, and the most affected being New Emerging Economies (NEC) such as Botswana. This is due to lack of expertise and resources to deal with existing ergonomics challenges. This study was aimed to evaluate occupational postures and the prevalence of musculoskeletal disorders among diamond polishers in a diamond company in Botswana. A case study was conducted with about 106 diamond polishers in Gaborone, Botswana. A case study was chosen because it can investigate and explore an issue thoroughly and deeply, and record behaviour over time so changes in behaviour can be identified. The Corlett and Bishop Body Map was used to determine frequency of MSDs symptoms in different body parts of the workers. This was then followed by the use of the Rapid Entire Body Assessment (REBA) to evaluate the occupational postural risks of MSDs. Descriptive statistics, chi square, and logistic regression were used for data analysis. The results of the study reveal that workers experienced pain in the upper back, lower back, shoulders, neck, and wrists with the most pain reported in the upper back (44.6%) and lower back (44.2%). However, the mean REBA score of 6.07 suggests that sawing, bruiting and polishing were the most dangerous processes in diamond polishing. The study recommends that a redesign of the diamond polishing workstations is necessary to accommodate the anthropometry characteristic of Batswana (people from Botswana) to prevent the development of MSDs.

Keywords: assessment, Botswana, diamond polishing, ergonomics, musculoskeletal disorders, occupational postural risks

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1450 Adsorption Behavior and Mechanism of Illite Surface under the Action of Different Surfactants

Authors: Xiuxia Sun, Yan Jin, Zilong Liu, Shiming Wei

Abstract:

As a critical mineral component of shale, illite is essential in oil exploration and development due to its surface hydration characteristics and action mechanism. This paper, starting from the perspective of the molecular structure of organic matter, uses molecular dynamics simulation technology to deeply explore the interaction mechanism between organic molecules and the illite surface. In the study, we thoroughly considered the forces such as van der Waals force, electrostatic force, and steric hindrance and constructed an illite crystal model covering C8-C18 modifiers. Subsequently, we systematically analyzed surfactants' adsorption behavior and hydration characteristics with different alkyl chain numbers, lengths, and concentrations on the illite surface. The simulation results show that surfactant molecules with shorter alkyl chains present a lateral monolayer or inclined double-layer arrangement on the illite surface, and these two arrangements may coexist under different concentration conditions. In addition, with the increase in the number of alkyl chains, the interlayer spacing of illite increases significantly. In contrast, the change in alkyl chain length has a limited effect on surface properties. It is worth noting that the change in functional group structure has a particularly significant effect on the wettability of the illite surface, and its influence even exceeds the change in the alkyl chain structure. This discovery gives us a new perspective on understanding and regulating the wetting properties. The results obtained are consistent with the XRD analysis and wettability experimental data in this paper, further confirming the reliability of the research conclusions. This study deepened our understanding of illite's hydration characteristics and mechanism. We provided new ideas and directions for the molecular design and application development of oilfield chemicals.

Keywords: illite, surfactant, hydration, wettability, adsorption

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1449 Effect of Infill Density and Pattern on the Compressive Strength of Parts Produced by Polylactic Acid Filament Using Fused Deposition Modelling

Authors: G. K. Awari, Vishwajeet V. Ambade, S. W. Rajurkar

Abstract:

The field of additive manufacturing is growing, and discoveries are being made. 3D printing machines are also being developed to accommodate a wider range of 3D printing materials, including plastics, metals (metal AM powders), composites, filaments, and other materials. There are numerous printing materials available for industrial additive manufacturing. Such materials have their unique characteristics, advantages, and disadvantages. In order to avoid errors in additive manufacturing, key elements such as 3D printing material type, texture, cost, printing technique and procedure, and so on must be examined. It can be complex to select the best material for a particular job. Polylactic acid (PLA) is made from sugar cane or cornstarch, both of which are renewable resources. "Black plastic" is another name for it. Because it is safe to use and print, it is frequently used in primary and secondary schools. This is also how FDM screen printing is done. PLA is simple to print because of its low warping impact. It's also possible to print it on a cold surface. When opposed to ABS, it allows for sharper edges and features to be printed. This material comes in a wide range of colours. Polylactic acid (PLA) is the most common material used in fused deposition modelling (FDM). PLA can be used to print a wide range of components, including medical implants, household items, and mechanical parts. The mechanical behaviour of the printed item is affected by variations in infill patterns that are subjected to compressive tests in the current investigation to examine their behaviour under compressive stresses.

Keywords: fused deposition modelling, polylactic acid, infill density, infill pattern, compressive strength

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1448 Internet-Delivered Cognitive Behaviour Therapy for Depression Comorbid with Diabetes: Preliminary Findings

Authors: Lisa Robins, Jill Newby, Kay Wilhelm, Therese Fletcher, Jessica Smith, Trevor Ma, Adam Finch, Lesley Campbell, Jerry Greenfield, Gavin Andrews

Abstract:

Background:Depression treatment for people living with depression comorbid with diabetes is of critical importance for improving quality of life and diabetes self-management, however depression remains under-recognised and under-treated in this population. Cost—effective and accessible forms of depression treatment that can enhance the delivery of mental health services in routine diabetes care are needed. Provision of internet-delivered Cognitive Behaviour Therapy (iCBT) provides a promising way to deliver effective depression treatment to people with diabetes. Aims:To explore the outcomes of the clinician assisted iCBT program for people with comorbid Major Depressive Disorder (MDD) and diabetes compared to those who remain under usual care. The main hypotheses are that: (1) Participants in the treatment group would show a significant improvement on disorder specific measures (Patient Health Questionnaire; PHQ-9) relative to those in the control group; (2) Participants in the treatment group will show a decrease in diabetes-related distress relative to those in the control group. This study will also examine: (1) the effect of iCBT for MDD on disability (as measured by the SF-12 and SDS), general distress (as measured by the K10), (2) the feasibility of these treatments in terms of acceptability to diabetes patients and practicality for clinicians (as measured by the Credibility/Expectancy Questionnaire; CEQ). We hypothesise that associated disability, and general distress will reduce, and that patients with comorbid MDD and diabetes will rate the program as acceptable. Method:Recruit 100 people with MDD comorbid with diabetes (either Type 1 or Type 2), and randomly allocate to: iCBT (over 10 weeks) or treatment as usual (TAU) for 10 weeks, then iCBT. Measure pre- and post-intervention MDD severity, anxiety, diabetes-related distress, distress, disability, HbA1c, lifestyle, adherence, satisfaction with clinicians input and the treatment. Results:Preliminary results comparing MDD symptom levels, anxiety, diabetes-specific distress, distress, disability, HbA1c levels, and lifestyle factors from baseline to conclusion of treatment will be presented, as well as data on adherence to the lessons, homework downloads, satisfaction with the clinician's input and satisfaction with the mode of treatment generally.

Keywords: cognitive behaviour therapy, depression, diabetes, internet

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1447 Physicochemical Characterization of Medium Alkyd Resins Prepared with a Mixture of Linum usitatissimum L. and Plukenetia volubilis L. Oils

Authors: Antonella Hadzich, Santiago Flores

Abstract:

Alkyds have become essential raw materials in the coating and paint industry, due to their low cost, good application properties and lower environmental impact in comparison with petroleum-based polymers. The properties of these oil-modified materials depend on the type of polyunsaturated vegetable oil used for its manufacturing, since a higher degree of unsaturation provides a better crosslinking of the cured paint. Linum usitatissimum L. (flax) oil is widely used to develop alkyd resins due to its high degree of unsaturation. Although it is intended to find non-traditional sources and increase their commercial value, to authors’ best knowledge a natural source that can replace flaxseed oil has not yet been found. However, Plukenetia volubilis L. oil, of Peruvian origin, contains a similar fatty acid polyunsaturated content to the one reported for Linum usitatissimum L. oil. In this perspective, medium alkyd resins were prepared with a mixture of 50% of Linum usitatissimum L. oil and 50% of Plukenetia volubilis L. oil. Pure Linum usitatissimum L. oil was also used for comparison purposes. Three different resins were obtained by varying the amount of glycerol and pentaerythritol. The synthesized alkyd resins were characterized by FT-IR, and physicochemical properties like acid value, colour, viscosity, density and drying time were evaluated by standard methods. The pencil hardness and chemical resistance behaviour of the cured resins were also studied. Overall, it can be concluded that medium alkyd resins containing Plukenetia volubilis L. oil have an equivalent behaviour compared to those prepared purely with Linum usitatissimum L. oil. Both Plukenetia volubilis L. oil and pentaerythritol have a remarkable influence on certain physicochemical properties of medium alkyd resins.

Keywords: alkyd resins, flaxseed oil, pentaerythritol, Plukenetia volubilis L. oil, protective coating

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1446 Evaluating the Dosimetric Performance for 3D Treatment Planning System for Wedged and Off-Axis Fields

Authors: Nashaat A. Deiab, Aida Radwan, Mohamed S. Yahiya, Mohamed Elnagdy, Rasha Moustafa

Abstract:

This study is to evaluate the dosimetric performance of our institution's 3D treatment planning system for wedged and off-axis 6MV photon beams, guided by the recommended QA tests documented in the AAPM TG53; NCS report 15 test packages, IAEA TRS 430 and ESTRO booklet no.7. The study was performed for Elekta Precise linear accelerator designed for clinical range of 4, 6 and 15 MV photon beams with asymmetric jaws and fully integrated multileaf collimator that enables high conformance to target with sharp field edges. Ten tests were applied on solid water equivalent phantom along with 2D array dose detection system. The calculated doses using 3D treatment planning system PrecisePLAN were compared with measured doses to make sure that the dose calculations are accurate for simple situations such as square and elongated fields, different SSD, beam modifiers e.g. wedges, blocks, MLC-shaped fields and asymmetric collimator settings. The QA results showed dosimetric accuracy of the TPS within the specified tolerance limits. Except for large elongated wedged field, the central axis and outside central axis have errors of 0.2% and 0.5%, respectively, and off- planned and off-axis elongated fields the region outside the central axis of the beam errors are 0.2% and 1.1%, respectively. The dosimetric investigated results yielded differences within the accepted tolerance level as recommended. Differences between dose values predicted by the TPS and measured values at the same point are the result from limitations of the dose calculation, uncertainties in the measurement procedure, or fluctuations in the output of the accelerator.

Keywords: quality assurance, dose calculation, wedged fields, off-axis fields, 3D treatment planning system, photon beam

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1445 The Fantasy of the Media and the Sexual World of Adolescents: The Relationship between Viewing Sexual Content on Television and Sexual Behaviour of Adolescents

Authors: Ifeanyi Adigwe

Abstract:

The influence of television on adolescents is prevalent and widespread because television is a powerful sex educator for adolescents. This study examined the relationship between viewing sexual content on television and sexual behaviour of adolescents in public senior secondary schools in Lagos, Nigeria. The study employed a survey research design with a structured questionnaire as instrument. The multi-stage sampling technique was adopted. Firstly, purposive sampling was adopted in selecting 3 educational districts namely: Agege, Maryland, and Agboju. These educational districts were chosen for convenience and its wide coverage area of public senior secondary schools in Lagos State. Secondly, the researcher adopted systematic sampling to select the schools. The schools were listed in alphabetical order in each district and every 10th school were selected, yielding 13 schools altogether. A total of 501 copies of questionnaire were administered to the students and a total 491 copies of the questionnaire were retrieved. Only 453 copies of the questionnaire met the inclusion criteria and were used for analysis. Data were analyzed using descriptive statistics, Pearson Correlation, Principal components analysis, and regression analysis. Results of correlation analysis showed a positive and significant relationship between adolescent sexual belief and their preference for sexual content in television (r =0.117, N =453, p=0.13), viewing sexual content on television and adolescent sexual behavior, (r =-0.112, N =453, p<0.05), adolescent television preference and their preference for sexual content in television (r =0.328, N =453, p<0.05), adolescent television preference and adolescent’s sexual behavior (r=0.093, N =453, p<0.05). However, a negative but significant relationship exists between adolescent’s sexual knowledge and their sexual behavior (r=-122, N=453, p=0.0009). Pearson’s correlation between adolescents’ sexual knowledge and sexual behavior shows that there is a positive significant but strong relationship between adolescent’s sexual knowledge and their sexual behavior (r=0.967, N=453, p<0.05). The results also show that adolescent’s preference for sexual content in television informs them about their sexuality, development and sexual health. The descriptive and inferential analysis of data revealed that the interaction among adolescent sexual belief, knowledge and adolescents’ preference of sexual in television and its resultant effect on adolescent sexual behavior is apparent because sexual belief and norms about sex of an adolescent can induce his television preference of sexual content on television. The study concludes that exposure to sexual content in television can impact on adolescent sexual behaviour. There is no doubt that the actual outcome of television viewing and adolescent sexual behavior remains controversial because adolescent sexual behavior is multifaceted and multi-dimensional. Since behavior is learned overtime, the frequency of exposure and nature of sexual content viewed overtime induces and hastens sexual activity.

Keywords: adolescent sexual behavior, Nigeria, sexual belief, sexual content, sexual knowledge, television preference

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1444 Environmental Awareness on Formal Education Level: A Program Approach through Physical Education Course

Authors: Jocelyn Floresca

Abstract:

This paper aimed to present the by-product of the introduction of environmental ecology awareness on a formal education level utilizing the program course of Physical Education, particularly in the tertiary level. It is based on the premise that the radical need for environmental protection may not only necessarily be the work of people in the pure sciences but also deemed necessary to look into more avenues of the school setting particularly in the field of Physical Education. In the Philippines, most schools’ Physical Education focuses on the advancement of sports, fitness and wellness which are mostly done in the confines of a closed building. The paper dwells into the introduction of Physical Education as an outdoor recreation activity where in the participants of the study had the opportunity to indulge in activities undertaken outside the confines of buildings and going into large areas of the environment. It looked into the individual participant’s environmental social behaviour and effects on the participant’s perceptions in terms of the set objectives of Physical Education before and after the study’s intervention. The study utilized the formal course in Physical Education on nature walks, mountaineering and bird watching as interventions to gain perceptions and understanding. The introduction of the environmental ecology activities as a formal Physical Education course has resulted in deeper awareness that led to understanding the need to protect the environment, appreciation of the value of natural areas and acquiring behaviour for a sustainable use of the environment during the practice of Physical Education. Also, prior to the introduction of environmental ecology in Physical Education as a formal study; participants have no knowledge of what dwells in the identified sites of intervention. Whereas after the study, participants were able to identify various species of birds and plants found in the sites of the study that may lead to further conservation of the particular species.

Keywords: appreciation, conservation, environmental ecology, outdoor

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1443 Factors Affecting Internet Behavior and Life Satisfaction of Older Adult Learners with Use of Smartphone

Authors: Horng-Ji Lai

Abstract:

The intuitive design features and friendly interface of smartphone attract older adults. In Taiwan, many senior education institutes offer smartphone training courses for older adult learners who are interested in learning this innovative technology. It is expected that the training courses can help them to enjoy the benefits of using smartphone and increase their life satisfaction. Therefore, it is important to investigate the factors that influence older adults’ behavior of using smartphone. The purpose of the research was to develop and test a research model that investigates the factors (self-efficacy, social connection, the need to seek health information, and the need to seek financial information) affecting older adult learners’ Internet behaviour and their life satisfaction with use of smartphone. Also, this research sought to identify the relationship between the proposed variables. Survey method was used to collect research data. A Structural Equation Modeling was performed using Partial Least Squares (PLS) regression for data exploration and model estimation. The participants were 394 older adult learners from smartphone training courses in active aging learning centers located in central Taiwan. The research results revealed that self-efficacy significantly affected older adult learner’ social connection, the need to seek health information, and the need to seek financial information. The construct of social connection yielded a positive influence in respondents’ life satisfaction. The implications of these results for practice and future research are also discussed.

Keywords: older adults, smartphone, internet behaviour, life satisfaction

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1442 The Determinants of Corporate Hedging Strategy

Authors: Ademola Ajibade

Abstract:

Previous studies have explored several rationales for hedging strategies, but the evidence provided by these studies remains ambiguous. Using a hand-collected dataset of 2460 observations of non-financial firms in eight African countries covering 2013-2022, this paper investigates the determinants and extent of corporate hedge use. In particular, this paper focuses on the link between country-specific conditions and the corporate hedging behaviour of firms. To our knowledge, this represents the first African studies investigating the association between country-specific factors and corporate hedging policy. The evidence based on both univariate and multivariate reveal that country-level corruption and government quality are important indicators of the decisions and extent of hedge use among African firms. However, the connection between country-specific factors as a rationale for corporate hedge use is stronger for firms located in highly corrupt countries. This suggest that firms located in corrupt countries are more motivated to hedge due to the large exposure they face. In addition, we test the risk management theories and observe that CEOs educational qualification and experience shape corporate hedge behaviour. We implement a lagged variables in a panel data setting to address endogeneity concern and implement an interaction term between governance indices and firm-specific variables to test for robustness. Generally, our findings reveal that institutional factors shape risk management decisions and have a predictive power in explaining corporate hedging strategy.

Keywords: corporate hedging, governance quality, corruption, derivatives

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1441 Cyclic Behaviour of Wide Beam-Column Joints with Shear Strength Ratios of 1.0 and 1.7

Authors: Roy Y. C. Huang, J. S. Kuang, Hamdolah Behnam

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Beam-column connections play an important role in the reinforced concrete moment resisting frame (RCMRF), which is one of the most commonly used structural systems around the world. The premature failure of such connections would severely limit the seismic performance and increase the vulnerability of RCMRF. In the past decades, researchers primarily focused on investigating the structural behaviour and failure mechanisms of conventional beam-column joints, the beam width of which is either smaller than or equal to the column width, while studies in wide beam-column joints were scarce. This paper presents the preliminary experimental results of two full-scale exterior wide beam-column connections, which are mainly designed and detailed according to ACI 318-14 and ACI 352R-02, under reversed cyclic loading. The ratios of the design shear force to the nominal shear strength of these specimens are 1.0 and 1.7, respectively, so as to probe into differences of the joint shear strength between experimental results and predictions by design codes of practice. Flexural failure dominated in the specimen with ratio of 1.0 in which full-width plastic hinges were observed, while both beam hinges and post-peak joint shear failure occurred for the other specimen. No sign of premature joint shear failure was found which is inconsistent with ACI codes’ prediction. Finally, a modification of current codes of practice is provided to accurately predict the joint shear strength in wide beam-column joint.

Keywords: joint shear strength, reversed cyclic loading, seismic vulnerability, wide beam-column joints

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1440 Democratic Information Behavior of Social Scientists and Policy Makers in India

Authors: Mallikarjun Vaddenkeri, Suresh Jange

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This research study reports results of information behaviour by members of faculty and research scholars of various departments of social sciences working at universities with a sample of 300 and Members of Legislative Assembly and Council with 216 samples in Karnataka State, India. The results reveal that 29.3% and 20.3% of Social Scientists indicated medium and high level of awareness of primary sources - Primary Journals are found to be at scale level 5 and 9. The usage of primary journals by social scientists is found to be 28% at level 4, 24% of the respondent’s opined use of primary Conference Proceedings at level 5 as medium level of use. Similarly, the use of Secondary Information Sources at scale 8 and 9 particularly in case of Dictionaries (31.0% and 5.0%), Encyclopaedias (22.3% and 6.3%), Indexing Periodicals (7.0% and 15.3%) and Abstracting Periodicals (5.7% and 20.7%). For searching information from Journals Literature available in CD-ROM version, Keywords (43.7%) followed by Keywords with logical operators (39.7%) have been used for finding the required information. Statistical inference reveals rejection of null hypothesis `there is no association between designation of the respondents and awareness of primary information resources’. On the other hand, educational qualification possessed by Legislative members, more than half of them possess graduate degree as their academic qualification (57.4%) and just 16.7% of the respondents possess graduate degree while only 26.8% of the respondents possess degree in law and just 1.8% possess post-graduate degree in law. About 42.6% indicated the importance of information required to discharge their duties and responsibilities as a Policy Maker in the scale 8, as a Scholar (27.8%) on a scale 6, as a politician (64.8%) on a scale 10 and as a Councillor (51.9%) on a scale 8. The most preferred information agencies/sources very often contacted for obtaining useful information are by means of contacting the people of Karnataka State Legislative Library, listening Radio programmes, viewing Television programmes and reading the newspapers. The methods adopted for obtaining needed information quite often by means of sending their assistants to libraries to gather information (35.2%) and personally visiting the information source (64.8%). The null hypotheses `There is no association between Members of Legislature and Opinion on the usefulness of the resources of the Karnataka State Legislature Library’ is accepted using F ANOVA test. The studies conclude with a note revamp the existing library system in its structure and adopt latest technologies and educate and train social scientists and Legislators in using these resources in the interest of academic, government policies and decision making of the country.

Keywords: information use behaviour, government information, searching behaviour, policy makers

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1439 Assessing Acceptability and Preference of Printed Posters on COVID-19 Related Stigma: A Post-Test Study Among HIV-Focused Health Workers in Greater Accra Region of Ghana

Authors: Jerry Fiave, Dacosta Aboagye, Stephen Ayisi-Addo, Mabel Kissiwah Asafo, Felix Osei-Sarpong, Ebenezer Kye-Mensah, Renee Opare-Otoo

Abstract:

Background: Acceptability and preference of social and behaviour change (SBC) materials by target audiences is an important determinant of effective health communication outcomes. In Ghana, however, pre-test and post-test studies on acceptability and preference of specific SBC materials for specific audiences are rare. The aim of this study was therefore to assess the acceptability and preference of printed posters on COVID-19 related stigma as suitable SBC materials for health workers to influence behaviours that promote uptake of HIV-focused services. Methods: A total of 218 health workers who provide HIV-focused services were purposively sampled in 16 polyclinics where the posters were distributed in the Greater Accra region of Ghana. Data was collected in March 2021 using an adapted self-administered questionnaire in Google forms deployed via WhatsApp to participants. The data were imported into SPSS version 27 where chi-square test and regression analyses were performed to establish association as well as strength of association between variables respectively. Results: A total of 142 participants (physicians, nurses, midwives, lab scientists, health promoters, diseases control officers) made up of 85(60%) females and 57(40%) males responded to the questionnaire, giving a response rate of 65.14%. Only 88 (61.97%) of the respondents were exposed to the posters. The majority of those exposed said the posters were informative [82(93.18%)], relevant [85(96.59%)] and attractive [83(94.32%)]. They [82(93.20%)] also rated the material as acceptable with no statistically significant association between category of health worker and acceptability of the posters (X =1.631, df=5, p=0.898). However, participants’ most preferred forms of material on COVID-19 related stigma were social media [38(26.76%)], television [33(23.24%)], SMS [19(13.38%)], and radio [18(12.70%)]. Clinical health workers were 4.88 times more likely to prefer online or electronic versions of SBC materials than nonclinical health workers [AOR= 4.88 (95% CI= 0.31-0.98), p=0.034]. Conclusions: Printed posters on COVID-19 related stigma are acceptable SBC materials in communicating behaviour change messages that target health workers in promoting uptake of HIV-focused services. Posters are however, not among the most preferred materials for health workers. It is therefore recommended that material assessment studies are conducted to inform the development of acceptable and preferred materials for target audiences.

Keywords: acceptability, AIDS, HIV, posters, preference, SBC, stigma, social and behaviour change communication

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1438 Making Good Samaritans: An Exploration of Criminal Liability for Failure to Rescue in England and Wales

Authors: Usmaan Siddiqui

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In England and Wales, there is no duty to rescue strangers. We will be investigating whether this is correct, and whether we should introduce a Good Samaritan law. In order to explore this, firstly, we will be exploring the nature of our moral duties. How far do our moral duties extend? Do they extend only to our family and friends, or do they also extend to strangers? Secondly, even if there does exist a moral duty, should this duty be enforced by criminal law? To what extent should the criminal law reflect morality? Under English criminal law, the consensus is, that it is not the job of the English criminal law to perfect human behaviour, and whilst the law should prevent us from causing harm, it should not force us to be good. This approach is radically different from many other European countries that actually do have a Good Samaritan law. If there are compelling in principle reasons to introduce a Good Samaritan law how would we deal with the pragmatic institutional constraints? Such a law has been stated as being unworkable in practice and difficult in defining its limits. In order to verify this, we shall carry out a comparative analysis between England and selected states in the US to gauge how successful the Good Samaritan law has been in dealing with these institutional constraints. In terms of methodology, as well as a comparative analysis, we shall also be carrying out a doctrinal analysis exploring what the English criminal law’s position is regarding Omissions. In conclusion, the findings so far are, whilst it is not the job of the law to perfect human behaviour, both respect for the law and the level of social co-operation will be greatly improved if the law encourages morally desirable conduct. Whilst it is possible for society to exist without a duty to assist the distressed, a society which ignores the vulnerable is cold, callous, and uncaring. After all, we all need to face up to the possibility that we may be one day be vulnerable and in need of urgent aid, and it is about time English criminal law, catches up with the majority of Europe and protects the vulnerable.

Keywords: criminal, law, omissions, philosophy

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1437 DNA Methylation 6mA and Histone Methylation Involved in Multi-/Trans-Generational Reproductive Effects in Caenorhabditis elegans Induced by Atrazine

Authors: Jiechen Yin, Xiang Hong, Ran Liu

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Atrazine (ATR), a widely used triazine herbicide, is an environmental endocrine disruptor that can cause health problems. However, whether there are multi/trans-generational reproductive impacts of ATR have not been studied to our best knowledge. Therefore, in this study, Caenorhabditis elegans was used as a preferable model organism to identify the multi/trans-generational reproductive toxicity of ATR. L1 larvae were exposed to different concentrations (0.0004–40 mg/L) of ATR for 48 h. Successive generations (F1 to F5) were fed without ATR and consecutive exposure. The results showed that ATR exposure during P0 decreased fecundity, including a reduction in fertilized eggs, oocytes, and ovulation rate, delayed gonadal development, and decreased the relative area of the gonad arm and germ cell number. Furthermore, continuous ATR exposure (P0–F5) causes a significant increase in reproductive toxicity in subsequent generations, although no significant toxicity occurred in the P0 generation after exposure to environmental-related concentrations, suggesting that ATR exposure might have cumulative effects. Likewise, parental exposure to ATR caused transgenerational toxicity impairments. Interestingly, reproductive toxicity not development toxicity was transmitted to several generations (F1–F4), and the F2 generation showed the most notable changes. QRT-PCR results showed that genes related to DNA methylation 6mA (damt-1, nmad-1) and histone H3 methylation (mes-4, met-2, set-25, set-2, and utx-1) can also be passed on to offspring. The function of H3K4 and H3K9 methylation were explored by using loss-of-function mutants for set-2, set-25, and met-2. Transmissible reproductive toxicity was absent in met-2(n4256), set-2(ok952), and set-25(n5021) mutants, which suggests that the histone methyltransferases H3K4 and H3K9 activity are indispensable for the transgenerational effect of ATR. Finally, the downstream genes of DNA methylation and histone H3 methylation were determined. ATR upregulated the expression of ZC317.7, hsp-6, and hsp-60. Mitochondrial stress in parental generation dependent transcription 6mA modifiers may establish these epigenetic marks in progeny.

Keywords: ATR, Caenorhabditis elegans, multi-/trans-generation, reproductive toxicity

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1436 Characterization, Classification and Fertility Capability Classification of Three Rice Zones of Ebonyi State, Southeastern Nigeria

Authors: Sunday Nathaniel Obasi, Chiamak Chinasa Obasi

Abstract:

Soil characterization and classification provide the basic information necessary to create a functional evaluation and soil classification schemes. Fertility capability classification (FCC) on the other hand is a technical system that groups the soils according to kinds of problems they present for management of soil physical and chemical properties. This research was carried out in Ebonyi state, southeastern Nigeria, which is an agrarian state and a leading rice producing part of southeastern Nigeria. In order to maximize the soil and enhance the productivity of rice in Ebonyi soils, soil classification, and fertility classification information need to be supplied. The state was grouped into three locations according to their agricultural zones namely; Ebonyi north, Ebonyi central and Ebonyi south representing Abakaliki, Ikwo and Ivo locations respectively. Major rice growing areas of the soils were located and two profile pits were sunk in each of the studied zones from which soils were characterized, classified and fertility capability classification (FCC) developed. Soil classification was done using United State Department of Agriculture (USDA) Soil Taxonomy and correlated with World Reference Base for soil resources. Results obtained classified Abakaliki 1 and Abakaliki 2 as Typic Fluvaquents (Ochric Fluvisols). Ikwo 1 was classified as Vertic Eutrudepts (Eutric Vertisols) while Ikwo 2 was classified as Typic Eutrudepts (Eutric Cambisols). Ivo 1 and Ivo 2 were both classified as Aquic Eutrudepts (Gleyic Leptosols). Fertility capability classification (FCC) revealed that all studied soils had mostly loamy topsoils and subsoils except Ikwo 1 with clayey topsoil. Limitations encountered in the studied soils include; dryness (d), low ECEC (e), low nutrient capital reserve (k) and water logging/ anaerobic condition (gley). Thus, FCC classifications were Ldek for Abakaliki 1 and 2, Ckv for Ikwo 1, LCk for Ikwo 2 while Ivo 1 and 2 were Legk and Lgk respectively.

Keywords: soil classification, soil fertility, limitations, modifiers, Southeastern Nigeria

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1435 Needs for Primary Prevention in Families with Mentally Ill Parents

Authors: Patricia Wahl, Dirk Bruland, Albert Lenz

Abstract:

Children of mentally ill parents are a large high risk group for mental disorders which is hardly reached by preventive programs. The children inherit a heightened risk to develop a mental disorder themselves during their lifetime, but they and their parents are often rejecting to seek help. To elicit the factors determining this prevention dilemma, an explorative qualitative interview study is conducted in 25 families with mentally ill parents and yet unaffected children. Inclusion criteria are the children’s age (7 to 14 years old) and that these children live together with the affected parent. With regard to the concept of Mental Health Literacy the following research questions are leading the Qualitative Content Analysis: What are the needs of families with mentally ill parents? How can their help-seeking behaviour be described? What are their subjective illness theories? And which influences do gender, ethnicity and socio-economic status have on needs, help-seeking and illness theories? Mental Health Literacy relates to the knowledge and attitudes towards mental disorders influencing the recognition, management or prevention of these disorders. The concept seems to be an interesting starting point for our analysis with the aim to understand antecedences and processes in the families more deeply. Results of an extensive literature review serve as deductive framework for our analysis, first findings from the interviews will be available up to the time of the conference and can be presented. They hopefully will give inside in the families’ living environment and help to adapt/develop interventions and in the long term reduce health inequalities. The project at hand is part of the Health Literacy in Childhood and Adolescence (HLCA) Research Consortium financed by the German Federal Ministry of Education and Research (BMBF).

Keywords: children of mentally ill parents, help-seeking behaviour, mental health literacy, prevention dilemma

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1434 Real Time PCR Analysis of microRNA Expression in Oral Cancer

Authors: Karl Kingsley

Abstract:

Many mechanisms are involved in the control of cellular differentiation and growth, which are often dysregulated in many cancers. Many distinct pathways are involved in these mechanisms of control, including deoxyribonuclease (DNA) methyltransferase and histone deacetylase (HDAC) activation that controls both genetic and epigenetic modifications and micro ribonucleic acid (RNA) expression. Less is known about the expression of DNA methyltransferase (DNMT) and HDAC in oral cancers and the effect on microRNA expression. The primary objective of this study was to evaluate the expression of DNMT and HDAC family members in oral cancer and the concomitant expression of cancer-associated microRNAs. Using commercially available oral cancers, including squamous cell carcinoma (SCC)-4, SCC-9, SCC-15, and SCC-25, RNA was extracted and screened for DNMT, HDAC, and microRNA expression using highly-specific primers and quantitative polymerase chain reaction (qPCR). These data revealed low or absent expression of DNMT-1, which is associated with cellular differentiation but increased expression of DNMT-3a and DNMT-3b in all SCC cell lines compared with normal non-cancerous cell controls. In addition, no expression of HDAC1 and HDAC2 expression was found among the normal, non-cancerous cells but was highly expressed in each of the SCC cell lines examined. Differential expression of oncogenic and cancer-associated microRNAs was also observed among the SCC cell lines, including miR-21, miR-133, miR-149, miR-155, miR-365, and miR-720. These findings also appeared to vary according to observed growth rates among these cells. These data may be the first to demonstrate the expression and association between HDAC and DNMT3 family members among oral cancers. In addition, the differential expression of these epigenetic modifiers may be associated with the expression of specific microRNAs in these cancers, which have not previously been observed to the best of the author's knowledge. In addition, some associations and relationships may exist between the expression of these biomarkers and the rates of growth and proliferation, which may suggest that these expression patterns might represent potentially useful biomarkers to determine tumor aggressiveness and other phenotypic behaviors among oral cancers.

Keywords: oral cancer, DNA methyltransferase, histone deacetylase, microRNA

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1433 Optimization of Acid Treatments by Assessing Diversion Strategies in Carbonate and Sandstone Formations

Authors: Ragi Poyyara, Vijaya Patnana, Mohammed Alam

Abstract:

When acid is pumped into damaged reservoirs for damage removal/stimulation, distorted inflow of acid into the formation occurs caused by acid preferentially traveling into highly permeable regions over low permeable regions, or (in general) into the path of least resistance. This can lead to poor zonal coverage and hence warrants diversion to carry out an effective placement of acid. Diversion is desirably a reversible technique of temporarily reducing the permeability of high perm zones, thereby forcing the acid into lower perm zones. The uniqueness of each reservoir can pose several challenges to engineers attempting to devise optimum and effective diversion strategies. Diversion techniques include mechanical placement and/or chemical diversion of treatment fluids, further sub-classified into ball sealers, bridge plugs, packers, particulate diverters, viscous gels, crosslinked gels, relative permeability modifiers (RPMs), foams, and/or the use of placement techniques, such as coiled tubing (CT) and the maximum pressure difference and injection rate (MAPDIR) methodology. It is not always realized that the effectiveness of diverters greatly depends on reservoir properties, such as formation type, temperature, reservoir permeability, heterogeneity, and physical well characteristics (e.g., completion type, well deviation, length of treatment interval, multiple intervals, etc.). This paper reviews the mechanisms by which each variety of diverter functions and discusses the effect of various reservoir properties on the efficiency of diversion techniques. Guidelines are recommended to help enhance productivity from zones of interest by choosing the best methods of diversion while pumping an optimized amount of treatment fluid. The success of an overall acid treatment often depends on the effectiveness of the diverting agents.

Keywords: diversion, reservoir, zonal coverage, carbonate, sandstone

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1432 Influence of BaTiO₃ on the Biological Behaviour of Hydroxyapatite: Collagen Composites

Authors: Cristina Busuioc, Georgeta Voicu, Sorin-Ion Jinga

Abstract:

The human bone presents in its dry form piezoelectric properties, which means that a mechanical stress results in electric polarization and an applied electric field causes strain. The immediate consequence was the revealing of piezoelectricity role in bone remodelling, as well as the integration of ceramic materials with piezoelectric behaviour in the composition of unitary or composite biomaterials. Thus, we prepared hydroxyapatite - collagen hybrid materials with barium titanate addition in order to achieve a better osseointegration. Barium titanate powder synthesized by a combined sol-gel-hydrothermal method, commercial hydroxyapatite and laboratory extracted collagen gel were employed as starting materials. Before the composites, fabrication, the powder with piezoelectric features was characterized in detail from the compositional, structural, morphological and electrical point of view. The next step was to elucidate the influence of barium titanate presence especially on the biological properties of the final materials. The biocompatibility of the hybrid supports without or with piezoelectric addition was investigated on mouse osteoblast cells through LDH cytotoxicity assay, LIVE/DEAD cell viability assay, and MTT cell proliferation assay. All results indicated that the analysed materials do not exert cytotoxic effects and present the ability to sustain cell survival and to promote their proliferation. In conclusion, barium titanate nanoparticles exhibit a good biocompatibility and osteoinductive properties, while the derived composite materials based on hydroxyapatite as oxide phase and collagen as polymeric phase can be successfully used for tissue engineering applications.

Keywords: barium titanate, hybrid composites, piezoelectricity, tissue engineering

Procedia PDF Downloads 322
1431 Between Efficacy and Danger: Narratives of Female University Students about Emergency Contraception Methods

Authors: Anthony Idowu Ajayi, Ezebunwa Ethelbert Nwokocha, Wilson Akpan, Oladele Vincent Adeniyi

Abstract:

Studies on emergency contraception (EC) mostly utilise quantitative methods and focus on medically approved drugs for the prevention of unwanted pregnancies. This methodological bias necessarily obscures insider perspectives on sexual behaviour, particularly on why specific methods are utilized by women who seek to prevent unplanned pregnancies. In order to privilege this perspective, with a view to further enriching the discourse and policy on the prevention and management of unplanned pregnancies, this paper brings together the findings from several focus groups and in-depth interviews conducted amongst unmarried female undergraduate students in two Nigerian universities. The study found that while the research participants had good knowledge of the consequences of unprotected sexual intercourses - with abstinence and condom widely used - participants’ willingness to rely only on medically sound measures to prevent unwanted pregnancies was not always mediated by such knowledge. Some of the methods favored by participants appeared to be those commonly associated with people of low socio-economic status in the society where the study was conducted. Medically unsafe concoctions, some outright dangerous, were widely believed to be efficacious in preventing unwanted pregnancy. Furthermore, respondents’ narratives about their sexual behaviour revealed that inadequate sex education, socio-economic pressures, and misconceptions about the efficacy of “crude” emergency contraception methods were all interrelated. The paper therefore suggests that these different facets of the unplanned pregnancy problem should be the focus of intervention.

Keywords: unplanned pregnancy, unsafe abortion, emergency contraception, concoctions

Procedia PDF Downloads 424
1430 Synthesis of Polystyrene Grafted Filler Nanoparticles: Effect of Grafting on Mechanical Reinforcement

Authors: M. Khlifa, A. Youssef, A. F. Zaed, A. Kraft, V. Arrighi

Abstract:

A series of PS-nanoparticles were prepared by grafting PS from both aggregated silica and colloidally silica using atom-transfer radical polymerisation (ATRP). The mechanical behaviour of the nanocomposites have been examined by differential scanning calorimetry (DSC)and dynamic mechanical thermal analysis (DMTA).

Keywords: ATRP, nanocomposites, polystyrene, reinforcement

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1429 A Virtual Reality Simulation Tool for Reducing the Risk of Building Content during Earthquakes

Authors: Ali Asgary, Haopeng Zhou, Ghassem Tofighi

Abstract:

Use of virtual (VR), augmented reality (AR), and extended reality technologies for training and education has increased in recent years as more hardware and software tools have become available and accessible to larger groups of users. Similarly, the applications of these technologies in earthquake related training and education are on the rise. Several studies have reported promising results for the use of VR and AR for evacuation behaviour and training under earthquake situations. They simulate the impacts that earthquake has on buildings, buildings’ contents, and how building occupants and users can find safe spots or open paths to outside. Considering that considerable number of earthquake injuries and fatalities are linked to the behaviour, our goal is to use these technologies to reduce the impacts of building contents on people. Building on our artificial intelligence (AI) based indoor earthquake risk assessment application that enables users to use their mobile device to assess the risks associated with building contents during earthquakes, we develop a virtual reality application to demonstrate the behavior of different building contents during earthquakes, their associate moving, spreading, falling, and collapsing risks, and their risk mitigation methods. We integrate realistic seismic models, building contents behavior with and without risk mitigation measures in virtual reality environment. The application can be used for training of architects, interior design experts, and building users to enhance indoor safety of the buildings that can sustain earthquakes. This paper describes and demonstrates the application development background, structure, components, and usage.

Keywords: virtual reality, earthquake damage, building content, indoor risks, earthquake risk mitigation, interior design, unity game engine, oculus

Procedia PDF Downloads 105
1428 Investigation the Photocatalytic Properties of Fe3O4-TiO2 Nanocomposites Prepared by Sonochemical Method

Authors: Zh. Saffari, A. Naeimi, M. S. Ekrami-Kakhki, F. Hamidi

Abstract:

Fe3O4 is one of the important magnetic oxides with spinel structure; it has exhibited unique electric and magnetic properties based on the electron transfer between Fe2+ and Fe3+ in the octahedral sites. Fe3O4 has received considerable attention in various areas such as cancer therapy, drug targeting, enzyme immobilization catalysis, magnetic cell separation, magnetic refrigeration systems and super-paramagnetic materials Fe3O4–TiO2 nanostructures were synthesized by simple, effective and new co-precipitation method assisted by ultrasonic reaction at room temperatures with organic surfactant. The effect of various parameters such as temperature, time, and power on the size and morphology of the product was investigated. Alternating gradient force magnetometer shows that Fe3O4 nanoparticles exhibit super-paramagnetic behaviour at room temperature. For preparation of nanocomposite, 1 g of TiO2 nanostructures were dispersed in 100 mL of ethanol. 0.25 g of Fe(NO3)2 and 2 mL of octanoic acid was added to the solution as a surfactant. Then, NaOH solution (1.5 M) was slowly added into the solution until the pH of the mixture was 7–8. After complete precipitation, the solution placed under the ultrasonic irradiation for 30 min. The product was centrifuged, washed with distilled water and dried in an oven at 100 °C for 3 h. The resulting red powder was calcinated at 800 °C for 3 h to remove any organic residue. The photocatalytic behaviour of Fe3O4–TiO2 nanoparticles was evaluated using the degradation of a Methyl Violet (MV) aqueous solution under ultraviolet light irradiation. As time increased, more and more MV was adsorbed on the nanoparticles catalyst, until the absorption peak vanish. The MV concentration decreased rapidly with increasing UV-irradiation time

Keywords: magnetic, methyl violet, nanocomposite, photocatalytic

Procedia PDF Downloads 255
1427 Studying the Bond Strength of Geo-Polymer Concrete

Authors: Rama Seshu Doguparti

Abstract:

This paper presents the experimental investigation on the bond behavior of geo polymer concrete. The bond behavior of geo polymer concrete cubes of grade M35 reinforced with 16 mm TMT rod is analyzed. The results indicate that the bond performance of reinforced geo polymer concrete is good and thus proves its application for construction.

Keywords: geo-polymer, concrete, bond strength, behaviour

Procedia PDF Downloads 508
1426 Effect of Reinforcement Density on the Behaviour of Reinforced Sand Under a Square Footing

Authors: Dhyaalddin Bahaalddin Noori Zangana

Abstract:

This study involves the behavior of reinforced sand under a square footing. A series of bearing capacity tests were performed on a small-scale laboratory model, which filled with a poorly-graded homogenous bed of sand, which was placed in a medium dense state using sand raining technique. The sand was reinforced with 40 mm wide household aluminum foil strips. The main studied parameters was to consider the effect of reinforcing strip length, with various linear density of reinforcement, number of reinforcement layers and depth of top layer of reinforcement below the footing, on load-settlement behavior, bearing capacity ratio and settlement reduction factor. The relation of load-settlement generally showed similar trend in all the tests. Failure was defined as settlement equal to 10% of the footing width. The recommended optimum reinforcing strip length, linear density of reinforcement, number of reinforcement layers and depth of top layer of reinforcing strips that give the maximum bearing capacity improvement and minimum settlement reduction factor were presented and discussed. Different bearing capacity ration versus length of the reinforcing strips and settlement reduction factor versus length of the reinforcing strips relations at failure were showed improvement of bearing capacity ratio by a factor of 3.82 and reduction of settlement reduction factor by a factor of 0.813. The optimum length of reinforcement was found to be 7.5 times the footing width.

Keywords: square footing, relative density, linear density of reinforcement, bearing capacity ratio, load-settlement behaviour

Procedia PDF Downloads 98
1425 Cross-Sectional Analysis of the Health Product E-Commerce Market in Singapore

Authors: Andrew Green, Jiaming Liu, Kellathur Srinivasan, Raymond Chua

Abstract:

Introduction: The size of Singapore’s online health product (HP) market (e-commerce) is largely unknown. However, it is recognized that a large majority comes from overseas and thus, unregulated. As buying HP from unauthorized sources significantly compromises public health safety, understanding e-commerce users’ demographics and their perceptions on online HP purchasing becomes a pivotal first step to form a basis for recommendations in Singapore’s pharmacovigilance efforts. Objective: To assess the prevalence of online HP purchasing behaviour among Singaporean e-commerce users. Methodology: This is a cross-sectional study targeting Singaporean e-commerce users recruited from various local websites and online forums. Participants were not randomized into study arms but instead stratified by random sampling method based on participants’ age. A self-administered anonymous questionnaire was used to explore participants' demographics, online HP purchasing behaviour, knowledge and attitude. The association of different variables with online HP purchasing behaviour was analysed using logistic regression statistics. Main outcome measures: Prevalence of HP e-commerce users in Singapore (%) and variables that contribute to the prevalence (adjusted prevalent ratio). Results: The study recruited 372 complete and valid responses. The prevalence of online HP consumers among e-commerce users in Singapore is estimated to be 55.9% (1.7 million consumers). Online purchasing of complementary HP (46.9%) was the most prevalent, followed by medical devices (21.6%) and Western medicine (20.5%). Multivariate analysis showed that age is an independent variable that correlates with the likelihood of buying HP online. The prevalence of HP e-commerce users is highest in the 35-44 age group (64.1%) and lowest among the 16-24 age group (36.4%). The most bought HP through the internet are vitamins and minerals (21.5%), non-herbal (15.9%), herbal (13.9%), weight loss (8.7%) and sports (8.4%) supplements. While the top 3 products are distributed equally between the genders, there is a skew towards female respondents (12.4% in females vs. 4.9% in males) for weight loss supplements and towards males (13.2% in males vs. 3.7% in females) for sports supplements. Even though online consumers are in the younger age brackets, our study found that up to 72.0% of HP bought online are bought for others (buyer’s family and/or friends). Multivariate analysis showed a statistically significant association between purchasing HP through online means and the perceptions that 'internet is safe' (adjusted Prevalence Ratio=1.15, CI 1.03-1.28), 'buying HP online is time saving' (PR=1.17, CI 1.01-1.36), and 'recognition of HP brand' (PR=1.21 CI 1.06-1.40). Conclusions: This study has provided prevalence data for online HP market in Singapore, and has allowed the country’s regulatory body to formulate a targeted pharmacovigilance approach to this growing problem.

Keywords: e-commerce, pharmaceuticals, pharmacovigilance, Singapore

Procedia PDF Downloads 363
1424 Investigating Role of Novel Molecular Players in Forebrain Roof-Plate Midline Invagination

Authors: Mohd Ali Abbas Zaidi, Meenu Sachdeva, Jonaki Sen

Abstract:

In the vertebrate embryo, the forebrain anlagen develops from the anterior-most region of the neural tube which is the precursor of the central nervous system (CNS). The roof plate located at the dorsal midline region of the forebrain anlagen, acts as a source of several secreted molecules involved in patterning and morphogenesis of the forebrain. One such key morphogenetic event is the invagination of the forebrain roof plate which results in separation of the single forebrain vesicle into two cerebral hemispheres. Retinoic acid (RA) signaling plays a key role in this process. Blocking RA signaling at the dorsal forebrain midline inhibits dorsal invagination and results in the absence of certain key features of this region, such as thinning of the neuroepithelium and a lowering of cell proliferation. At present we are investigating the possibility of other signaling pathways acting in concert with RA signaling to regulate this process. We have focused on BMP signaling, which we found to be active in a mutually exclusive domain to that of RA signaling within the roof plate. We have also observed that there is a change in BMP signaling activity on modulation of RA signaling indicating an antagonistic relationship between the two. Moreover, constitutive activation of BMP signaling seems to completely inhibit thinning and partially affect invagination, leaving the lowering of cell proliferation in the midline unaffected. We are employing in-silico modeling as well as molecular manipulations to investigate the relative contribution if any, of regional differences in rates of cell proliferation and thinning of the neuroepithelium towards the process of invagination. We have found expression of certain cell adhesion molecules in forebrain roof-plate whose mRNA localization across the thickness of neuroepithelium is influenced by Bmp and RA signaling, giving regional rigidity to roof plate and assisting invagination. We also found expression of certain cytoskeleton modifiers in a localized small domains in invaginating forebrain roof plate suggesting that midline invagination is under control of many factors.

Keywords: bone morphogenetic signaling, cytoskeleton, cell adhesion molecules, forebrain roof plate, retinoic acid signaling

Procedia PDF Downloads 155
1423 Effect of High Intensity Ultrasonic Treatment on the Micro Structure, Corrosion and Mechanical Behavior of ac4c Aluminium Alloy

Authors: A.Farrag Farrag, A. M. El-Aziz Abdel Aziz, W. Khlifa Khlifa

Abstract:

Ultrasonic treatment is a promising process nowadays in the engineering field due to its high efficiency and it is a low-cost process. It enhances mechanical properties, corrosion resistance, and homogeneity of the microstructure. In this study, the effect of ultrasonic treatment and several casting conditions on microstructure, hardness and corrosion behavior of AC4C aluminum alloy was examined. Various ultrasonic treatments of the AC4C alloys were carried out to prepare billets for thixocasting process. Treatment temperatures varied from about 630oC and cooled down to under ultrasonic field. Treatment time was about 90s. A 600-watts ultrasonic system with 19.5 kHz and intensity of 170 W/cm2 was used. Billets were reheated to semisolid state and held for 5 minutes at 582 oC and temperatures (soaking) using high-frequency induction system, then thixocasted using a die casting machine. Microstructures of the thixocast parts were studied using optical and SEM microscopes. On the other hand, two samples were conventionally cast and poured at 634 oC and 750 oC. The microstructure showed a globular none dendritic grains for AC4C with the application of UST at 630-582 oC, Less dendritic grains when the sample was conventionally cast without the application of UST and poured at 624 oC and a fully dendritic microstructure When the sample was cast and poured at 750 oC without UST .The ultrasonic treatment during solidification proved that it has a positive influence on the microstructure as it produced the finest and globular grains thus it is expected to increase the mechanical properties of the alloy. Higher values of corrosion resistance and hardness were recorded for the ultrasound-treated sample in comparison to cast one.

Keywords: ultrasonic treatment, aluminum alloys, corrosion behaviour, mechanical behaviour, microstructure

Procedia PDF Downloads 353