Search results for: alcohol dependence

Authors: Imen Dhaou

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This study examines conditional Value at Risk by applying the GJR-EVT-Copula model, and finds the optimal portfolio for eight Dow Jones Islamic-conventional pairs. Our methodology consists of modeling the data by a bivariate GJR-GARCH model in which we extract the filtered residuals and then apply the Peak over threshold model (POT) to fit the residual tails in order to model marginal distributions. After that, we use pair-copula to find the optimal portfolio risk dependence structure. Finally, with Monte Carlo simulations, we estimate the Value at Risk (VaR) and the conditional Value at Risk (CVaR). The empirical results show the VaR and CVaR values for an equally weighted portfolio of Dow Jones Islamic-conventional pairs. In sum, we found that the optimal investment focuses on Islamic-conventional US Market index pairs because of high investment proportion; however, all other index pairs have low investment proportion. These results deliver some real repercussions for portfolio managers and policymakers concerning to optimal asset allocations, portfolio risk management and the diversification advantages of these markets.

Keywords: CVaR, Dow Jones Islamic index, GJR-GARCH-EVT-pair copula, portfolio optimization

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Authors: Silvia Riva, Ezekiel Chinyio

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Introduction: Workers in different sectors are prone to stress at varying levels. They also respond to stress in different ways. An inspiration was to study stress development amongst workers in a work dangerous setting (Construction Industry) as well as how they cope with specific stress incidences. Objective: The overarching objective of the study was to study and correlate between stress and coping strategies. The research was conducted in an organizational industrial setting, and its findings on the coping actions of construction workers are reported in this article. Methods: An online cross-sectional survey was conducted with 80 participants aged 18-62. These were working for three different construction organizations in the West Midland region of the UK. Their coping actions were assessed using the COPE Inventory (Carver, 2013) instrument while the level of stress was assessed by the Perceived Stress Scale (Cohen, 1994). Results: Out of 80 workers (20 female, 25%, mean age 40.66), positive reinterpretation (M=4.15, SD=2.60) and active coping (M=4.18, SD=2.55) were the two most adaptive strategies reported by the workers while the most frequent maladaptive behavior was mental disengagement (M=3.62, SD=2.25). Among the maladaptive tactics, alcohol and drug abuse was a significant moderator in stress reactions (t=6.12, p=.000). Conclusion: Some maladaptive strategies are adopted by construction workers to cope with stress. So, it could be argued that programs of stress prevention and control in the construction industry have a basis to develop solutions that can improve and strengthen effective interventions when workers are stressed or getting stressed.

Keywords: coping, organization, strategies, stress

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Authors: Yibin Qiu, Yubo Ouyang, Shihan Li, Guorui Zhang, Qi Li, Weirong Chen

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This paper aims at exploring the impacts of high dimensional dependencies of wind speed among wind farms on probabilistic optimal power flow. To obtain the reactive power optimization faster and more accurately, a mixture vine Copula structure model combining the K-means clustering, C vine copula and D vine copula is proposed in this paper, through which a more accurate correlation model can be obtained. Moreover, a Modified Backtracking Search Algorithm (MBSA), the three-point estimate method is applied to probabilistic optimal power flow. The validity of the mixture vine copula structure model and the MBSA are respectively tested in IEEE30 node system with measured data of 3 adjacent wind farms in a certain area, and the results indicate effectiveness of these methods.

Keywords: mixture vine copula structure model, three-point estimate method, the probability integral transform, modified backtracking search algorithm, reactive power optimization

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Authors: Ikrima Zaleda Zia, Devi Fitri Kumalasari, Rosita Khusna, Farah Hidayati, Ilham Fajrul Haq, Amin Yusuf Efendi

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Fertilizer is one of the production factors that are important to agriculture. Fertilizers contribution to the agricultural sector improvement is quite high. Fertilizers scarcity on the society are giving effect to agricultural sector, that is decreasing farmers production. Through a system called Kemal Propuri, society will be taught how to be independent, especially in terms of supplying the fertilizer and how to earn extra income besides of relying on the agriculture production. This research aims to determine implementation measures of Kemal Propuri in realizing farmers independence. This research was designed to use descriptive research with a qualitative approach. In this case, writers are trying to make an illustration of the increasing role of KUD (rural unit cooperative) through Kemal Propuri system (Independence System Through Individual Fertilizer Production) towards farmer independence. It can be concluded that Kemal Propuri system can contribute in order to achieve farmers independence. Independence fertilizer production will overcome farmers dependence of the subsidized fertilizer from the government.

Keywords: Kemal Propuri, KUD (Rural Unit Cooperative), independence farmers, fertilizer production

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Authors: H. Bhowmik, A. Faisal, Ahmed Al Yaarubi, Nabil Al Alawi

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Experiments are conducted to analyze the steady-state and the power-on transient natural convection heat transfer from a horizontal cylinder mounted in a vertical up flow circular duct. The heat flux ranges from 177 W/m² to 2426 W/m² and the Rayleigh number ranges from 1×10⁴ to 4.35×10⁴. For natural air flow and constant heat flux condition, the effects of heat transfer around the cylinder under steady-state condition are investigated. The steady-state results compare favorably with that of the available data. The effects of transient heat transfer data on different angular position of the thermocouple (0^o, 90^o, 180^o) are also reported. It is observed that the transient heat transfer around the cylinder is strongly affected by the position of thermocouples. In the transient region, the rate of heat transfer obtained at 90^o and 180^o are higher than that of stagnation point (0^o). Finally, the dependence of the average Nusselt number on Rayleigh number for steady and transient natural convection heat transfer are analyzed, and a correlation equation is presented.

Keywords: Fourier number, Nusselt number, Rayleigh number, steady state, transient

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Authors: Asma Salman, Brian Gabbitas, Peng Cao, Deliang Zhang

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The performance of a coating is strongly dependent upon its microstructure, which in turn is dependent on the characteristics of the feedstock powder. This study involves the evaluation and performance of a titanium-based composite coating produced by the HVOF (high-velocity oxygen fuel) spraying method. The feedstock for making the composite coating was produced using high energy mechanical milling of TiO2 and Al powders followed by a combustion reaction. The characteristics of the feedstock powder were improved by treating it with an organic binder. Two types of coatings were produced using treated and untreated feedstock powders. The microstructures and characteristics of both types of coatings were studied, and their thermal shock resistance was accessed by dipping into molten aluminum. The results of this study showed that feedstock treatment did not have a significant effect on the microstructure of the coatings. However, it did affect the uniformity, thickness and surface roughness of the coating on the steel substrate. A coating produced by an untreated feedstock showed better thermal shock resistance in molten aluminum compared with the one produced by PVA (polyvinyl alcohol) treatment.

Keywords: coating, feedstock, powder processing, thermal shock resistance, thermally spraying

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Authors: S. Assylbekova, D. Zolotareva, A. Dauletbakov, Ye. Belyankova, S. Bayazit, A. Basharimova, A. Zazybin, A. Isimberlenova, A. Kakimova, M. Aydemir, A. Kairullinova

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Transfer hydrogenation (TH) is a key process in organic chemistry, especially in pharmaceutical and agrochemical synthesis, offering a safer and more sustainable approach compared to traditional methods. This work is devoted to the synthesis and use of ruthenium catalysts containing phosphinite ligands in TH reactions. Ruthenium complexes are particularly noteworthy for their effectiveness in asymmetric TH. Their stability and adaptability to different reaction environments make them ideal for both laboratory-scale and industrial applications. Phosphinite ligands (P(OR)R'2) are used in the synthesis of complexes to improve their properties. These ligands are known for their ability to finely tune the electronic and steric properties of metal centers. The electron-donating nature of the phosphorus atom, combined with the variability in the R and R' groups, allows for significant customization of the catalyst's properties. The purpose and difference of the work is to study the incorporation of a hydrophilic ionic liquid into the composition of a phosphinite ligand, which will then be converted into a catalyst. The technique involves the synthesis of a phosphinite ligand with an ionic liquid at room temperature under an inert atmosphere and then a ruthenium complex. Next, the TH reactions of acetophenone and its derivatives are carried out using the resulting catalyst. The conversion of ketone to alcohol is analyzed using a gas chromatograph. This study contributes to the understanding of the influence of catalyst physico-chemical properties on transfer hydrogenation results.

Keywords: transfer hydrogenation, ruthenium, catalysts, phosphinite ligands

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Authors: Yogesh Dalvi, Ruby Varghese, Nibu Varghese, C. K. Krishnan Nair

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Introduction: The Genus Phellinus, locally known as Phansomba is a well-known traditional folk medicine. Especially, in Western Ghats of India, many tribes use several species of Phellinus for various ailments related to teeth, throat, tongue, stomach and even wound healing. It is one of the few mushrooms which play a pivotal role in Ayurvedic Dravyaguna. Aim: The present study focuses on to investigate phytochemical analysis, antioxidant, and antitumor (in vitro and in vivo) potential of Phellinus robinae from South India, Kerala Material and Methods: The present study explores the following: 1. Phellinus samples were collected from Ranni, Pathanamthitta district of Kerala state, India from Artocarpus heterophyllus Lam. and species were identified using rDNA region. 2. The fruiting body was shadow dried, powdered and extracted with 50% alcohol using water bath at 60°C which was further condensed by rotary evaporator and lyophilized at minus 40°C temperature. 3. Secondary metabolites were analyzed by using various phytochemical screening assay (Hager’s Test, Wagner’s Test, Sodium hydroxide Test, Lead acetate Test, Ferric chloride Test, Folin-ciocalteu Test, Foaming Test, Benedict’s test, Fehling’s Test and Lowry’s Test). 4. Antioxidant and free radical scavenging activity were analyzed by DPPH, FRAP and Iron chelating assay. 5. The antitumor potential of Water alcohol extract of Phellinus (PAWE) is evaluated through In vitro condition by Trypan blue dye exclusion method in DLA cell line and In vivo by murine model. Result and Discussion: Preliminary phytochemical screening by various biochemical tests revealed presence of a variety of active secondary molecules like alkaloids, flavanoids, saponins, carbohydrate, protein and phenol. In DPPH and FRAP assay PAWE showed significantly higher antioxidant activity as compared to standard Ascorbic acid. While, in Iron chelating assay, PAWE exhibits similar antioxidant activity that of Butylated Hydroxytoluene (BHT) as standard. Further, in the in vitro study, PAWE showed significant inhibition on DLA cell proliferation in dose dependent manner and showed no toxicity on mice splenocytes, when compared to standard chemotherapy drug doxorubicin. In vivo study, oral administration of PAWE showed dose dependent tumor regression in mice and also raised the immunogenicity by restoring levels of antioxidant enzymes in liver and kidney tissue. In both in vitro and in vivo gene expression studies PAWE up-regulates pro-apoptotic genes (Bax, Caspases 3, 8 and 9) and down- regulates anti-apoptotic genes (Bcl2). PAWE also down regulates inflammatory gene (Cox-2) and angiogenic gene (VEGF). Conclusion: Preliminary phytochemical screening revealed that PAWE contains various secondary metabolites which contribute to its antioxidant and free radical scavenging property as evaluated by DPPH, FRAP and Iron chelating assay. PAWE exhibits anti-proliferative activity by the induction of apoptosis through a signaling cascade of death receptor-mediated extrinsic (Caspase8 and Tnf-α), as well as mitochondria-mediated intrinsic (caspase9) and caspase pathways (Caspase3, 8 and 9) and also by regressing angiogenic factor (VEGF) without any inflammation or adverse side effects. Hence, PAWE serve as a potential antioxidant and antitumor agent.

Keywords: antioxidant, antitumor, Dalton lymphoma ascites (DLA), fungi, Phellinus robinae

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Authors: D. Gueribiz, F. Jacquemin, S. Fréour

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During their service life, composite materials are submitted to humid environments. The moisture absorbed by their matrix polymer induced internal stresses which can lead to multi-scale damage and may reduce the lifetime of composite structures. The estimation of internal stresses is based at a first on realistic evaluation of the diffusive behavior of composite materials. Generally, the modeling and simulation of the diffusive behavior of composite materials are extensively investigated through decoupled models based on the assumption of Fickien behavior. For these approaches, the concentration and the deformation (or stresses), the two state variables of the problem considered are governed by independent equations which are solved separately. In this study, a model coupling diffusive behavior with stresses state for a polymer matrix composite reinforced with impermeable fibers is proposed, the investigation of diffusive behavior is based on a more general thermodynamic approach which introduces a dependence of diffusive behavior on internal stresses state. The coupled diffusive behavior modeling was established in first for homogeneous and isotropic matrix and it is, thereafter, extended to impermeable unidirectional composites.

Keywords: composites materials, moisture diffusion, effective moisture diffusivity, coupled moisture diffusion

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Authors: Shivani Saini

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The effect of vertical throughflow on the onset of convection in Rivlin-Ericksen Elastico-Viscous nanofluid with convective boundary condition is investigated. The flow is stimulated with modified Darcy model under the assumption that the nanoparticle volume fraction is not actively managed on the boundaries. The heat conservation equation is formulated by introducing the convective term of nanoparticle flux. A linear stability analysis based upon normal mode is performed, and an approximate solution of eigenvalue problems is obtained using the Galerkin weighted residual method. Investigation of the dependence of the Rayleigh number on various viscous and nanofluid parameter is performed. It is found that through flow and nanofluid parameters hasten the convection while capacity ratio, kinematics viscoelasticity, and Vadasz number do not govern the stationary convection. Using the convective component of nanoparticle flux, critical wave number is the function of nanofluid parameters as well as the throughflow parameter. The obtained solution provides important physical insight into the behavior of this model.

Keywords: Darcy model, nanofluid, porous layer, throughflow

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Authors: Merab Mamuladze, Mixeil Lejava, Fadiko Abuselidze

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At present, where most of the soils of Georgia have a small contour, the demand for small-capacity technical means, in particular motoblocks, has increased. Motoblocks perform agricultural work for various purposes, where the work process is performed by the operator, who experiences various magnitudes of vibration, impact, noise, and in general, as a result of long-term work production, causes body damage, dynamic load, and respiratory diseases in people. In the scientific paper, the dependence on the vibration of different types of diesel fuel is investigated in the case of five different revolutions in the internal combustion engine. Studies have shown that fuel and engine speed are the only risk factors that contradict the ISO 5349-2(2004) international standard. The experience of four years of work studies showed that 10% of operators received various types of injuries as a result of working with motoblocks. Experiments also showed that the amount of vibration decreases when the number of revolutions of the engine increases, and in the case of using biodiesel fuel, the damage risk factor is 5-10%, and in the case of using conventional diesel, this indicator has gone up to 20%.

Keywords: engine, vibration, biodiesel, high risk factor, working conditions

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Authors: C. Lanzerstorfer

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The off-gas from the basic oxygen furnace (BOF), where pig iron is converted into steel, is treated in the primary ventilation system. This system is in full operation only during oxygen-blowing when the BOF converter vessel is in a vertical position. When pig iron and scrap are charged into the BOF and when slag or steel are tapped, the vessel is tilted. The generated emissions during charging and tapping cannot be captured by the primary off-gas system. To capture these emissions, a secondary ventilation system is usually installed. The emissions are captured by a canopy hood installed just above the converter mouth in tilted position. The aim of this study was to investigate the dependence of Zn and other components on the particle size of BOF secondary ventilation dust. Because of the high temperature of the BOF process it can be expected that Zn will be enriched in the fine dust fractions. If Zn is enriched in the fine fractions, classification could be applied to split the dust into two size fractions with a different content of Zn. For this air classification experiments with dust from the secondary ventilation system of a BOF were performed. The results show that Zn and Pb are highly enriched in the finest dust fraction. For Cd, Cu and Sb the enrichment is less. In contrast, the non-volatile metals Al, Fe, Mn and Ti were depleted in the fine fractions. Thus, air classification could be considered for the treatment of dust from secondary BOF off-gas cleaning.

Keywords: air classification, converter dust, recycling, zinc

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Authors: Abhishikta Ghosh Roy

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Breast cancer is the most common malignancy among women globally, including India. Human breast cancer results from the genetic and environmental interaction. The present study attempts to understand the molecular heterogeneity of BRCA1 and BRCA2 genes, as well as to understand the association of various lifestyle and reproductive variables for the Breast Cancer risk. The study was conducted amongst 110 patients and 128 controls with total DNA sequencing of flanking and coding regions of BRCA1 BRCA2 genes that revealed ten Single Nucleotide Polymorphisms (SNPs) (6 novels). The controls selected for the study were age, sex and ethnic group matched. After written and informed consent biological samples were collected from the subjects. After detailed molecular analysis, significant (p < 0.005) molecular heterogeneity is revealed in terms of SNPs in BRCA1 (4 Exonic & 1 Intronic) and BRCA2 (2exonic and 3 Intronic) genes. The augmentation study investigated significant (p < 0.05) association with positive family history, early age at menarche, irregular menstrual periods, menopause, prolong contraceptive use, nulliparity, history of abortions, consumption of alcohol and smoking for breast cancer risk. To the best of authors knowledge, this study is the first of its kind, envisaged that the identification of the SNPs and modification of the lifestyle factors might aid to minimize the risk among the Bengalee Hindu females.

Keywords: breast cancer, BRCA, lifestyle, India

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Authors: H. Ben Khlifa, W. Cheikhrouhou, R. M'nassri

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The Orthorhombic Pr0.8Na0.2MnO3 ceramic was prepared in Polycrystalline form by a Pechini sol–gel method and its structural, magnetic, electrical, and dielectric properties were investigated experimentally. A structural study confirms that the sample is a single phase. Magnetic measurements show that the sample is a charge ordered Manganite. The sample undergoes two successive magnetic phase transitions with the variation of temperature: a charge ordering transition occurred at TCO = 212 K followed by a Paramagnetic (PM) to ferromagnetic (FM) transition around TC = 115 K. From an electrical point of view, a saturation region was marked in the conductivity as a function of Temperature s(T) curves at a specific temperature. The dc-conductivity (sdc) reaches a maximum value at 240 K. The obtained results are in good agreement with the temperature dependence of the average normalized change (ANC). We found that the conduction mechanism was governed by small polaron hopping (SPH) in the high-temperature region and by variable range hopping (VRH) in the low-temperature region. Complex impedance analysis indicates the presence of a non-Debye relaxation phenomenon in the system. Also, the compound was modeled by an electrical equivalent circuit. Then, the contribution of the grain boundary in the transport properties was confirmed.

Keywords: manganites, preparation methods, magnetization, magnetocaloric effect, electrical and dielectric

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Authors: Jiajun Wang, Xiaoge Li

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The purpose of the aspect-level sentiment analysis task is to identify the sentiment polarity of aspects in a sentence. Currently, most methods mainly focus on using neural networks and attention mechanisms to model the relationship between aspects and context, but they ignore the dependence of words in different ranges in the sentence, resulting in deviation when assigning relationship weight to other words other than aspect words. To solve these problems, we propose a new aspect-level sentiment analysis model that combines a multi-channel convolutional network and graph convolutional network (GCN). Firstly, the context and the degree of association between words are characterized by Long Short-Term Memory (LSTM) and self-attention mechanism. Besides, a multi-channel convolutional network is used to extract the features of words in different ranges. Finally, a convolutional graph network is used to associate the node information of the dependency tree structure. We conduct experiments on four benchmark datasets. The experimental results are compared with those of other models, which shows that our model is better and more effective.

Keywords: aspect-level sentiment analysis, attention, multi-channel convolution network, graph convolution network, dependency tree

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Authors: Joseph K. A. Johnson

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Hypertension affects 20 percent of the people within the ages 55 upward in Ghana. Of these, almost one-third are unaware of their condition. Also at the age of 55, more men turned to have hypertension than women. After that age, the condition becomes more prevalent with women. Hypertension is significantly more common in African Americans of both sexes than the racial or ethnic groups. This study was conducted to determine the causes of high blood pressure in Ashanti Region, Ghana. The study employed One Hundred and Seventy (170) respondents. The sample population for the study was all the available respondents at the time of the data collection. The research was conducted using primary data where convenience sampling was used to locate the respondents. A set of questionnaire were used to gather the data for the study. The gathered data was analysed using principal component analysis. The study revealed that, personal description, lifestyle behavior and risk awareness as some of the causes of high blood pressure in Ashanti Region. The study therefore recommend that people must be advice to see to their personal characteristics that may contribute to high blood pressure such as controlling of their temper and how to react perfectly to stressful situations. They must be educated on the factors that may increase the level of their blood pressure such as the essence of seeing a medical doctor before taking in any drug. People must also be made known by the public health officers to those lifestyles behaviour such as smoking and drinking of alcohol which are major contributors of high blood pressure.

Keywords: high blood pressure, principal component analysis, hypertension, public health

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Authors: Rajni Kant Panik, Deependra Singh, Manju Singh

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Despite significant advances in the treatment of severe burn injury, infection and sepsis persist as frequent causes of morbidity and mortality for burn victims due to extensive compromise of the skin and contiguous tissue that serve as a protective barrier against microbial invasion. In the setting of a burn wound infection, Staphylococcus aureus is the most commonly isolated pathogens from bloodstream infections in burn care hospitals. We aimed to develop a biocompatible system of Poly vinyl alcohol (PVA)-sodium alginate hydrogel carrying multiple drugs- catalase and mupirocin in controlled manner for effective and complete burn wound healing. PLGA nanoparticles of Catalase and mupirocin were prepared by homogenization method and optimized system was incorporated in PVA-sodium alginate slurry. PVA-sodium alginate hydrogels were prepared by freeze thaw method. The prepared dispersion was casted into films to prepare multiphase hydrogel system and characterized by in vitro and in vivo studies. The study clearly showed the beneficial effect of antioxidant enzyme and antibiotic in the treatment of infected burn wound, as evidenced by the reduced incidence of wound infection and the shortening of healing time.

Keywords: burn wound, catalase, mupirocin, wound healing

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Authors: Rabih O. Al-Kaysi, Lingyan Zhu, Muhannah K. Al-Muhannah, Christopher J. Bardeen

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(E)-3-(Anthracen-9-yl)acrylic acid (9-AYAA) 1 exhibits a strong photomechanical response in bulk crystals but is challenging to grow in microcrystalline form. High quality microcrystals of this molecule could not be grown using techniques like sublimation, reprecipitation, and the floating drop method. If the tertbutyl ester of 9-AYAA is used as a starting material, however, high quality, size-uniform microwires could be grown via acid catalyzed hydrolysis. 9-AYAA microwires with uniform length and thickness were produced after a suspension of (E)-tert-butyl 3-(anthracen-9-yl)acrylate ester 2 microparticles was tumble-mixed in a mixture of phosphoric acid and sodium dodecyl sulfate at 35 °C. The dependence of the results on temperature, surfactant and precursor concentration, and mixing mode was investigated. This chemical reaction-growth method was extended to grow microplates of 9-anthraldehyde 3 using the corresponding acylal 4 as the starting material. Under 475 nm irradiation, the 9-AYAA microwires undergo a photoinduced coiling–uncoiling transition, while the 9-anthraldehyde microplates undergo a folding–unfolding transition.

Keywords: photomechanical, surfactant, organic crystals, uniform

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Authors: Daniel Etim Jacob, Samuel Onadeko, Edem A. Eniang, Imaobong Ufot Nelson

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This paper examined determinants of income diversification among households in support zones communities of national parks in Nigeria. This involved the use household data collected through questionnaires administered randomly among 1009 household heads in the study area. The data obtained were analyzed using probability and non-probability statistical analysis such as regression and analysis of variance to test for mean difference between parks. The result obtained indicates that majority of the household heads were male (92.57%0, between the age class of 21 – 40 years (44.90%), had non-formal education (38.16%), were farmers (65.21%), owned land (95.44%), with a household size of 1 – 5 (36.67%) and an annual income range of ₦401,000 - ₦600,000 (24.58%). Mean Simpson index of diversity showed a general low (0.375) level of income diversification among the households. Income, age, off-farm dependence, education, household size and occupation where significant (p<0.01) factors that affected households’ income diversification. The study recommends improvement in the existing infrastructures and social capital in the communities as avenues to improve the livelihood and ensure positive conservation behaviors in the study area.

Keywords: income diversification, protected area, livelihood, poverty, Nigeria

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Authors: Anis A. Ansari, M. Kamil

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The development of 3D printing technology has allowed the manufacturing industry to create parts with a high degree of automation, increased design freedom, and improved mechanical performance. Fused deposition modelling (FDM) is a 3D printing technique in which successive layers of thermoplastic polymer are deposited and controlled to create a three-dimensional product. In this study, process parameters such as nozzle temperature and printing speed were chosen to investigate their effects on hardness properties. 3D printed specimens were fabricated by an FDM 3D printer from Polylactic acid (PLA) polymer. After analysis, it was observed that the hardness property is much influenced by print speed and nozzle temperature parameters. Maximum hardness was achieved at higher print speed which indicates that the Shore D hardness is directly proportional to the print speed. Moreover, at higher print speed, it has no significant dependence on the nozzle temperature. Hardness is also influenced by nozzle temperature, though to a lesser extent. The hardness slightly lowers when the nozzle temperature is raised from 190 to 210 oC, but due to improved bonding between each raster, a further rise in temperature increases the hardness property.

Keywords: 3D printing, fused deposition modeling (FDM), polylactic acid (PLA), print speed, nozzle temperature, hardness property

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Authors: Rochelyn Dona, Serdar Satar

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The aim of this study was to evaluate the biological parameters of A. fabae Scopoli (Hemiptera: Aphididae). Developmental, survival, and reproductive data were collected for Aphis fabae reared on detached bean leaves (Phaseolus vulgaris L.) ‘pinto beans’ at five temperature regimes (12, 16, 20, 24, and 28 °C), 65% relative humidity (RH), relative and a photoperiod of 16:8 (LD) h. The developmental times of immature stages ranged from 16, 65 days at 12°C to 5.70 days at 24°C, but a slight increase again at 28°C (6.62 days). At 24°C from this study presented the developmental threshold for A. fabae slightly to 24°C. The average longevity of mature females significantly decreased from 42.32 days at 12°C to 16.12 days at 28°C. The reproduction rate per female was 62.27 at 16°C and 12.72 at 28°C. The mean generation period of the population ranged from 29.24 at 12°C to 11.50 at 28°C. The highest intrinsic rate of increase (rm = 0.41) were recorded at 24°C, the lowest at 12°C (rm = 0.15). It was evident that temperatures over 28°C augmented the development time, accelerated the death ratio of the nymphal stages, Shrunk Adult longevity, and reduced fecundity. The optimal range of temperature for the population growth of A. fabae on the bean was 16°C-24°C, according to this study.

Keywords: developmental time, intrinsic rate, reproduction period, temperature dependence

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Authors: Michael Stevens

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David Hunter, a musicologist, has suggested that both Beethoven and Handel had chronic lead poisoning from the wine that they drank. These two eminent musical composers had some striking similarities. Beethoven had alcohol dependency and preferred wine, to which lead had been added to improve the taste. Handel was obese due to an eating disorder that included drinking tainted wine after large meals. They both had paresthesia of their extremities that they interpreted as rheumatism. This is a common sensory symptom from chronic lead poisoning. Their differences are marked in that Beethoven was profoundly deaf by the end of his life, whereas Handel had remarkably good hearing. Handel had paresis of three fingers of his right hand, whereas Beethoven lacked any motor symptoms. Beethoven reported recurrent abdominal pain suggestive of lead colic, whereas it can only be inferred that this symptom was present in Handel. Lead poisoning is likely in Handel because his paralysis was consistent with radial nerve involvement in the dominant hand. In addition, it was cured by hot baths, which have been shown to reduce total body lead content by exchanging with iron and calcium ions in water. Although lead produces predominantly motor symptoms in classic or subacute lead poisoning, and sensory symptoms in chronic lead poisoning, lead poisoning causes a variety of symptoms that depending on duration and level of exposure, are extremely variable from person to person. It therefore seems likely that Handel had lead poisoning, but extremely likely that Beethoven did because of the confirmatory finding of high levels of lead deep in his skull bone, which is a good measure of total body burden.

Keywords: beethoven, handel, lead, poisoning

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Authors: Radhapiyari Laishram, Chongtham Jiten, K. Chandramani Singh

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During the last decade, there has been a significant growth in developing lead-free piezoelectric ceramics which have the potential to replace the currently dominant but highly superior lead-based piezoelectric materials such as PZT. Among the lead-free piezoelectrics, (K0.5Na0.5)NbO3 - based piezoceramics are promising candidates due to their superior piezoelectric properties and high Curie temperatures. In this work, (K0.5Na0.5)(Nb1-xVx)O3 powders with x varying the range 0 to 0.05 were synthesized from the raw materials K2CO3, Na2CO3, Nb2O5, and V2O5. These powders were ball milled with high-energy Retsch PM 100 ball mill using isopropanol as the medium at the speed of 200rpm for a duration of 8h. The milled powders were sintered at 1080oC for 1h. The crystalline phase of all the calcined powders and corresponding ceramics prepared was found to be perovskite with orthorhombic symmetry. The ceramic with V5+ content of x=0.03 exhibits the maximum values in density of 4.292 g/cc, room temperature dielectric constant (εr) of 432, and piezoelectric charge constant (d33) of 93pC/N. For this sample, the dielectric tan δ loss remains relatively low over a wide temperature range. The temperature dependence of P-E hysteresis loops has been investigated for the ceramic composition with x = 0.03.

Keywords: dielectric properties, ferroelectric properties, perovskie, piezoelectric properties

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Authors: Suman Paik, P. V. Durgaprasad, Bijan K. Dutta

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A study combining experimental and numerical investigation on the deformation behaviour of single crystals of copper is presented in this paper. Cylindrical samples were cut in specific orientations from high purity copper single crystal and subjected to uniaxial compression loading at quasi-static strain rate. The stress-strain curves along two different crystallographic orientations were then extracted. In order to study and compare the deformation responses, a single crystal plasticity model incorporating non-Schmid effects was developed assuming cross-slip plays an important role in orientation of the material. By making use of crystal plasticity finite element method, the model was applied to investigate the orientation dependence of the stress-strain behaviour of two crystallographic orientations. Finally, details of slip activities of deformed crystals were investigated by linking the orientation of slip lines with the theoretical traces of possible crystallographic planes. The experimentally determined active slip modes were matched with those determined by simulations.

Keywords: crystal plasticity, modelling, non-Schmid effects, finite elements, finite strain

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Authors: Wonil Nam, Xiang Ren, Inyoung Kim, Masoud Agah, Wei Zhou

Abstract:

Despite its ultrasensitive detection capability, surface-enhanced Raman spectroscopy (SERS) faces challenges as a quantitative biochemical analysis tool due to the significant dependence of local field intensity in hotspots on nanoscale geometric variations of plasmonic nanostructures. Therefore, despite enormous progress in plasmonic nanoengineering of high-performance SERS devices, it is still challenging to quantitatively correlate the measured SERS signals with the actual molecule concentrations at hotspots. A significant effort has been devoted to developing SERS calibration methods by introducing internal standards. It has been achieved by placing Raman tags at plasmonic hotspots. Raman tags undergo similar SERS enhancement at the same hotspots, and ratiometric SERS signals for analytes of interest can be generated with reduced dependence on geometrical variations. However, using Raman tags still faces challenges for real-world applications, including spatial competition between the analyte and tags in hotspots, spectral interference, laser-induced degradation/desorption due to plasmon-enhanced photochemical/photothermal effects. We show that electronic Raman scattering (ERS) signals from metallic nanostructures at hotspots can serve as the internal calibration standard to enable quantitative SERS analysis and improve biostatistical analysis. We perform SERS with Au-SiO₂ multilayered metal-insulator-metal nano laminated plasmonic nanostructures. Since the ERS signal is proportional to the volume density of electron-hole occupation in hotspots, the ERS signals exponentially increase when the wavenumber is approaching the zero value. By a long-pass filter, generally used in backscattered SERS configurations, to chop the ERS background continuum, we can observe an ERS pseudo-peak, IERS. Both ERS and SERS processes experience the |E|⁴ local enhancements during the excitation and inelastic scattering transitions. We calibrated IMRS of 10 μM Rhodamine 6G in solution by IERS. The results show that ERS calibration generates a new analytical value, ISERS/IERS, insensitive to variations from different hotspots and thus can quantitatively reflect the molecular concentration information. Given the calibration capability of ERS signals, we performed label-free SERS analysis of living biological systems using four different breast normal and cancer cell lines cultured on nano-laminated SERS devices. 2D Raman mapping over 100 μm × 100 μm, containing several cells, was conducted. The SERS spectra were subsequently analyzed by multivariate analysis using partial least square discriminant analysis. Remarkably, after ERS calibration, MCF-10A and MCF-7 cells are further separated while the two triple-negative breast cancer cells (MDA-MB-231 and HCC-1806) are more overlapped, in good agreement with the well-known cancer categorization regarding the degree of malignancy. To assess the strength of ERS calibration, we further carried out a drug efficacy study using MDA-MB-231 and different concentrations of anti-cancer drug paclitaxel (PTX). After ERS calibration, we can more clearly segregate the control/low-dosage groups (0 and 1.5 nM), the middle-dosage group (5 nM), and the group treated with half-maximal inhibitory concentration (IC50, 15 nM). Therefore, we envision that ERS calibrated SERS can find crucial opportunities in label-free molecular profiling of complicated biological systems.

Keywords: cancer cell drug efficacy, plasmonics, surface-enhanced Raman spectroscopy (SERS), SERS calibration

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Authors: Lavanya Dharmendran, Shenuka Singh, Sona Baburathanam

Abstract:

The aim of the study is to understand the level of awareness in a community of a specific region of Kuwait regarding oral cancer and its screening methods so as to enhance the uptake of oral cancer screening methods. This is a cross-sectional study comprising 100 adult participants residing in the governate of Farwaniya, Kuwait. Participants of above 18 years of both genders will be selected using convenience sampling. Data collection includes the administration of a self-administered questionnaire. The questionnaire comprises three sections, each section assessing the knowledge, attitudes and practices of the participants’ opinions about oral cancer and screening methods. Data will be analyzed using Humphris Oral Cancer Knowledge Scale. Inferential statistics will be done using Chi-Square or Fisher’s exact test for categorical data. A level of p<.05 will be established as being significant. All ethical considerations, such as respect for personal confidentiality and informed consent, will be applied in this study. This study revealed that although respondents were aware of the term oral cancer, more than half of the study participants were unaware of the symptoms associated with this condition. Smoking and alcohol were identified as risk factors for oral cancer, but the majority of participants did not identify the Human Papilloma Virus (HPV) as an added risk factor. This suggests a greater need for dental practitioners to include educational strategies in routine dental visits to ensure greater awareness of oral cancer.

Keywords: oral cancer, oral screening, oral public health, oral health

Procedia PDF Downloads 56

Authors: Khawlh A. Alzubaidi, Khadijah B. Alziyadi, Amor M. Alsayari

Abstract:

The discovery of a dilute magnetic semiconductor (DMS) in which ferromagnetism is carrier-mediated and persists above room temperature is a major step toward the implementation of spintronic devices for processing, transferring, and storing of information. Among the many types of DMS materials which have been investigated, Mn-doped GaAs has become one of the best candidates for technological application. However, despite major developments over the last few decades, the maximum Curie temperature (~200 K) remains well below room temperature. In this work, we have studied the effect of Mn content and strain on the GaMnAs effective masses of electron, heavy and light holes calculated in the different crystallographic direction. Also, the Curie temperature in the DMS GaMnAs alloy is determined. Compilation of GaMnAs band parameters have been carried out using the 8-band k.p model based on Lowdin perturbation theory where spin orbit, sp-d exchange interaction, and biaxial strain are taken into account. Our results show that effective masses, calculated along the different crystallographic directions, have a strong dependence on strain, ranging from -2% (tensile strain) to 2% (compressive strain), and Mn content increased from 1 to 5%. The Curie temperature is determined within the mean-field approach based on the Zener model.

Keywords: diluted magnetic semiconductors, k.p method, effective masses, curie temperature, strain

Procedia PDF Downloads 76

Authors: S. A. A. Nabeela Nasreen, S. Sundarrajan, S. A. Syed Nizar, Seeram Ramakrishna

Abstract:

Metal-organic frameworks (MOFs) have attracted considerable interest due to its diverse pore size tunability, fascinating topologies and extensive uses in fields such as catalysis, membrane separation, chemical sensing, etc. Zeolitic imidazolate frameworks (ZIFs) are a class of MOF with porous crystals containing extended three-dimensional structures of tetrahedral metal ions (e.g., Zn) bridged by Imidazolate (Im). Selected ZIFs are used to separate solvent/solvent mixtures. A layer by layer formation of the nanocomposite of Zinc oxide (ZnO) and ZIF on a ceramic support using a solvothermal method was engaged and tested for target solvent/solvent separation. Metal oxide layer was characterized by XRD, SEM, and TEM to confirm the smooth and continuous coating for the separation process. The chemical composition of ZIF films was studied by using X-Ray absorption near-edge structure (XANES) spectroscopy. The obtained ceramic tube with metal oxide and ZIF layer coating were tested for its packing density, thickness, distribution of seed layers and variation of permeation rate of solvent mixture (isopropyl alcohol (IPA)/methyl isobutyl ketone (MIBK). Pervaporation technique was used for the separation to achieve a high permeation rate with separation ratio of > 99.5% of the solvent mixture.

Keywords: metal oxide, membrane, pervaporation, solvothermal, ZIF

Procedia PDF Downloads 183

Authors: Je Young Lee, Hee Sung Kim, Kwang Ho Choi, Joonhoo Lim, Sebum Chun, Hyung Keun Lee

Abstract:

A purpose of this study is to develop efficient detection method for Global Navigation Satellite Systems (GNSS) applications based on adaptive estimation. Due to dependence of radio frequency signals, GNSS measurements are dominated by systematic errors in receiver’s operating environment. Thus, to utilize GNSS for aerospace or ground vehicles requiring high level of safety, unhealthy measurements should be considered seriously. For the reason, this paper proposes adaptive fault detection method to deal with unhealthy measurements in various harsh environments. By the proposed method, the test statistics for fault detection is generated by estimated measurement noise. Pseudorange and carrier-phase measurement noise are obtained at time propagations and measurement updates in process of Carrier-Smoothed Code (CSC) filtering, respectively. Performance of the proposed method was evaluated by field-collected GNSS measurements. To evaluate the fault detection capability, intentional faults were added to measurements. The experimental result shows that the proposed detection method is efficient in detecting unhealthy measurements and improves the accuracy of GNSS positioning under fault occurrence.

Keywords: adaptive estimation, fault detection, GNSS, residual

Procedia PDF Downloads 555

Authors: T. Maruyama, T. Saida, S. Naritsuka, S. Iijima

Abstract:

Single-walled carbon nanotubes (SWCNTs) are generally synthesized by chemical vapor deposition (CVD) using Fe, Co, and Ni as catalysts. However, due to the Ostwald ripening of metal catalysts, the diameter distribution of the grown SWCNTs is considerably wide (>2 nm), which is not suitable for electronics applications. In addition, reduction in the growth temperature is desirable for fabricating SWCNT devices compatible with the LSI process. Herein, we performed SWCNT growth by alcohol catalytic CVD using platinum-group metal catalysts (Pt, Rh, and Pd) because these metals have high melting points, and the reduction in the Ostwald ripening of catalyst particles is expected. Our results revealed that web-like SWCNTs were obtained from Pt and Rh catalysts at growth temperature between 500 °C and 600 °C by optimizing the ethanol pressure. The SWCNT yield from Pd catalysts was considerably low. By decreasing the growth temperature, the diameter and chirality distribution of SWCNTs from Pt and Rh catalysts became small and narrow. In particular, the diameters of most SWCNTs grown using Pt catalysts were below 1 nm and their diameter distribution was considerably narrow. On the contrary, SWCNTs can grow from Rh catalysts even at 300 °C by optimizing the growth condition, which is the lowest temperature recorded for SWCNT growth. Our results demonstrated that platinum-group metals are useful for the growth of small-diameter SWCNTs and facilitate low-temperature growth.

Keywords: carbon nanotube, chemical vapor deposition, catalyst, platinum, rhodium, palladium

Procedia PDF Downloads 328