Search results for: oxygen reduction

Authors: Ali A. Al-Jazaairry, Tahsin T. Sabbagh

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Presence of cavities in soil predictably induces ground deformation and changes in soil stress, which might influence adjacent existing pile foundations, though the effect of twin cavities on a nearby pile needs to be understood. This research is an attempt to identify the behaviour of piles subjected to axial load and embedded in cavitied clayey soil. A series of finite element modelling were conducted to investigate the performance of piled foundation located in such soils. The validity of the numerical simulation was evaluated by comparing it with available field test and alternative analytical model. The study involved many parameters such as twin cavities size, depth, spacing between cavities, and eccentricity of cavities from the pile axis on the pile performance subjected to axial load. The study involved many cases; in each case, a critical value has been found in which cavities’ presence has shown minimum impact on the behaviour of pile. Load-displacement relationships of the affecting parameters on the pile behaviour were presented to provide helpful information for designing piled foundation situated near twin underground cavities. It was concluded that the presence of the cavities within the soil mass reduces the ultimate capacity of pile. This reduction differs according to the size and location of the cavity.

Keywords: axial load, clay, finite element, pile, twin cavities, ultimate capacity

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Authors: Jiaqi Dong, Qing-Hua Qin, Yi Xiao

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Some of the most fundamental challenges of elastic metamaterials (EMMs) optimization can be attributed to the high consumption of computational power resulted from finite element analysis (FEA) simulations that render the optimization process inefficient. Furthermore, due to the inherent mesh dependence of FEA, minuscule geometry features, which often emerge during the later stages of optimization, induce very fine elements, resulting in enormously high time consumption, particularly when repetitive solutions are needed for computing the objective function. In this study, a surrogate modelling algorithm is developed to reduce computational time in structural optimization of EMMs. The surrogate model is constructed based on a multilayer feedforward artificial neural network (ANN) architecture, trained with prepopulated eigenfrequency data prepopulated from FEA simulation and optimized through regime selection with genetic algorithm (GA) to improve its accuracy in predicting the location and width of the primary elastic band gap. With the optimized ANN surrogate at the core, a Nelder-Mead (NM) algorithm is established and its performance inspected in comparison to the FEA solution. The ANNNM model shows remarkable accuracy in predicting the band gap width and a reduction of time consumption by 47%.

Keywords: artificial neural network, machine learning, mechanical metamaterials, Nelder-Mead optimization

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Authors: Cécile Dufloux, Klaus Böttcher, Heike Oppermann, Jürgen Wollweber

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Hexagonal aluminum nitride (AlN) is a promising candidate for several wide band gap semiconductor compound applications such as deep UV light emitting diodes (UVC LED) and fast power transistors (HEMTs). To date, bulk AlN single crystals are still commonly grown from the physical vapor transport (PVT). Single crystalline AlN wafers obtained from this process could offer suitable substrates for a defect-free growth of ultimately active AlGaN layers, however, these wafers still lack from small sizes, limited delivery quantities and high prices so far.Although there is already an increasing interest in the commercial availability of AlN wafers, comparatively cheap Si, SiC or sapphire are still predominantly used as substrate material for the deposition of active AlGaN layers. Nevertheless, due to a lattice mismatch up to 20%, the obtained material shows high defect densities and is, therefore, less suitable for high power devices as described above. Therefore, the use of AlN with specially adapted properties for optical and sensor applications could be promising for mass market products which seem to fulfill fewer requirements. To respond to the demand of suitable AlN target material for the growth of AlGaN layers, we have designed an innovative technology based on reactive plasma spraying. The goal is to produce coarse grained AlN boules with N-terminated columnar structure and high purity. In this process, aluminum is injected into a microwave stimulated nitrogen plasma. AlN, as the product of the reaction between aluminum powder and the plasma activated N2, is deposited onto the target. We used an aluminum filament as the initial material to minimize oxygen contamination during the process. The material was guided through the nitrogen plasma so that the mass turnover was 10g/h. To avoid any impurity contamination by an erosion of the electrodes, an electrode-less discharge was used for the plasma ignition. The pressure was maintained at 600-700 mbar, so the plasma reached a temperature high enough to vaporize the aluminum which subsequently was reacting with the surrounding plasma. The obtained products consist of thick polycrystalline AlN layers with a diameter of 2-3 cm. The crystallinity was determined by X-ray crystallography. The grain structure was systematically investigated by optical and scanning electron microscopy. Furthermore, we performed a Raman spectroscopy to provide evidence of stress in the layers. This paper will discuss the effects of process parameters such as microwave power and deposition geometry (specimen holder, radiation shields, ...) on the topography, crystallinity, and stress distribution of AlN.

Keywords: aluminum nitride, polycrystal, reactive plasma spraying, semiconductor

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Authors: Phyo Wai Aung, Sysoev Oleg Evgenevich, Boris Necolavet Maryin

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The article deals with theoretical problems of correlation of processes of microstructure changes of structural materials under cyclic loading and acoustic emission. The ways of the evolution of a microstructure under the influence of cyclic loading are shown depending on the structure of the initial crystal structure of the material. The spectra of the frequency characteristics of acoustic emission signals are experimentally obtained when testing titanium samples for cyclic loads. Changes in the fractal dimension of the acoustic emission signals in the selected frequency bands during the evolution of the microstructure of structural materials from the action of cyclic loads, as well as in the destruction of samples, are studied. The experimental samples were made of VT-20 structural material widely used in aircraft and rocket engineering. The article shows the striving of structural materials for synergistic stability and reduction of the fractal dimension of acoustic emission signals, in accordance with the degradation of the microstructure, which occurs as a result of fatigue processes from the action of low cycle loads. As a result of the research, the frequency range of acoustic emission signals of 100-270 kHz is determined, in which the fractal dimension of the signals, it is possible to most reliably predict the durability of structural materials.

Keywords: cyclic loadings, material structure changing, acoustic emission, fractal dimension

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Authors: Fatima Zohra Ibn Majdoub Hassani, Ivan Lavandera, Joseph Kreit

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This study explored the effects of different organic solvents, temperature, and the amount of glycerol on the alcohol dehydrogenase (ADH)-catalysed stereoselective reduction of different ketones. These conversions were then analyzed by gas chromatography. It was found that when the amount of deep eutectic solvents (DES) increases, it can improve the stereoselectivity of the enzyme although reducing its ability to convert the substrate into the corresponding alcohol. Moreover, glycerol was found to have a strong stabilizing effect on the ADH from Ralstonia sp. (E. coli/ RasADH). In the case of organic solvents, it was observed that the best conversions into the alcohols were achieved with DMSO and hexane. It was also observed that temperature decreased the ability of the enzyme to convert the substrates into the products and also affected the selectivity. In addition to that, the recycling of DES up to three times gave good conversions and enantiomeric excess results and glycerol showed a positive effect in the stability of various ADHs. Using RasADH, a good conversion and enantiomeric excess into the S-alcohol were obtained. It was found that an enhancement of the temperature disabled the stabilizing effect of glycerol and decreased the stereoselectivity of the enzyme. However, for other ADHs a temperature increase had an opposite positive effect, especially with ADH-T from Thermoanaerobium sp. One of the objectives of this study was to see the effect of cofactors such as NAD(P) on the biocatlysis activities of ADHs.

Keywords: alcohol dehydrogenases, DES, gas chromatography, RasADH

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Authors: Yahaya Taiwo, Adedayo M. Segun

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This study investigated the effect of postweld soaking temperature on mechanical properties of AISI 1018 steel plate welded in aqueous environment. Pairs of 90 x 70 x 12 mm, AISI 1018 steel plates were welded with weld zone beyond distance 10 mm from weld centerline immersed in a water jacket at 25°C. The welded specimens were tempered at temperature of 200, 300, 400, 500 and 600°C for 1.5 hours. Tensile, hardness and toughness tests at distances 15, 30, 45 and 60 mm from the weld centreline with micro structural evaluation were carried out. The results show that the aqueous environment as-weld sample exhibited higher hardness and tensile strength values of 45.3 HV and 448.12 N/mm2 respectively while the hardness and tensile strength of aqueous environment postweld heat treated samples were 44.9 HV and 378.98 N/mm2. This revealed 0.82% and 15.4% reduction in hardness and strength respectively. The metallographic tests showed that the postweld heat treated AISI 1018 steel micro structure contained tempered martensite with ferritic structure and precipitation of carbides. Postweld heat treatment produced materials of lower hardness and improved toughness.

Keywords: air weld samples, aqueous environment weld samples, soaking temperature, water jacket

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Authors: Prof. Hao Mao, Phd Qia Wei, Dr.Siwei Cao

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The administrative system is the organisational carrier for managing the operation of the market and the basic guarantee for achieving innovation incentives. This paper takes the reform of provincial administrative institutions in the process of Chinese national intellectual property administrative system reform in 2018 as a quasi-natural experiment to assess the impact of IP administrative system reform on enterprise innovation. The study finds that reducing the independence of some provincial administrative institutions will lead to a reduction in the number of local enterprises' innovations and a decrease in the quality of innovations, which is mainly triggered by a decrease in R&D investment due to a decrease in the strength of subsidy policies. The new round of intellectual property administrative system reform in 2023 elevated the administrative status of China National Intellectual Property Administration (CNIPA), and re-strengthened the top-level design and centralization of IP administration. This paper clarifies the role of the 2018 IP administrative system reform on China's market innovation, provides empirical evidence for the properly handling government market relations and property rights incentives and other institutional designs, and also provides empirical references for further promoting the improvement of national and local IP institutional mechanisms and the implementation of the innovation-driven development strategy in the new round of reform.

Keywords: intellectual property, administrative systems, reform, high-quality innovation

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Authors: Mohamad Reza Khodabakhsh

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The present study investigated the effectiveness of attachment-based family therapy on maladaptive schemas and depressive symptoms of adolescence. This study was a quasi-experimental study, and a pre-test and post-test design with a control group were used. In this study, the study population included all adolescence. The sample consisted of 30 adolescents who were selected by the available sampling method. Then they were randomly divided into experimental (n = 15) and control (n = 15) groups. Data were collected in this study using the Beck Depression Inventory (1974) and the short form of Young's early maladaptive schema questionnaire (1988). After taking the pre-test, group implementation of family therapy based on attachment style was presented for 11 sessions of two and a half hours for two months in the experimental group. At the end of the sessions, both groups were retested, and the data were analyzed using analysis of covariance in SPSS-22 software. The results showed that attachment-based family therapy led to a significant reduction in maladaptive schemas, including emotional deprivation, rejection/abandonment, mistrust/abuse, social isolation, disability/shame, dependence/inadequacy, vulnerability/trauma, and depressive symptoms were compared to the control group. It can be concluded that this treatment has an effect on maladaptive schemas and symptoms of depression.

Keywords: attachment-based family therapy, maladaptive schemas, depressive symptoms, adolescence

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Authors: Albert T. Akume, Yahya M. Abdullahi

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The impact of poverty on individual and society is grave, hence the efforts by the government to eradicate or alleviate. In Nigeria the various efforts to reduce rural poverty by empowering them and making the process of their development self-sustaining have ended dismally. That notwithstanding, government determination to conquer poverty has not diminish as in the early 1990s the government with financial collaboration from the World Bank and African Development Bank introduced the fadama project. It is against this backdrop that this paper uses the documentary and analytical research methods to examine the implication the fadama development project has for community capacity development and human security in Nigeria. From the analysis it was discovered the fadama project improved household income of fadama farmers, community empowerment, participatory development planning and support for demand driven productive investment in farm and non-farm activities including community infrastructures. Despite this impressive result the fadama project is challenged by conflict especially in northern Nigeria and late delivery of necessary farm consumables that aid improved productivity. It was therefore recommended that the government should strengthen her various state security institutions to proactively mitigate conflicts and to ensure that farm consumables and other support services reach farmers timely.

Keywords: capacity development, empowerment, fadama, human security, poverty reduction, theory of change, sustainable development

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Authors: R. R. Ramsheeja, R. Sreeraj

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For view the internal structures of the human body such as liver, brain, kidney etc have a wide range of different modalities for medical images are provided nowadays. Computer Tomography is one of the most significant medical image modalities. In this paper use CT liver images for study the use of automatic computer aided techniques to calculate the volume of the liver tumor. Segmentation method is used for the detection of tumor from the CT scan is proposed. Gaussian filter is used for denoising the liver image and Adaptive Thresholding algorithm is used for segmentation. Multiple Region Of Interest(ROI) based method that may help to characteristic the feature different. It provides a significant impact on classification performance. Due to the characteristic of liver tumor lesion, inherent difficulties appear selective. For a better performance, a novel proposed system is introduced. Multiple ROI based feature selection and classification are performed. In order to obtain of relevant features for Support Vector Machine(SVM) classifier is important for better generalization performance. The proposed system helps to improve the better classification performance, reason in which we can see a significant reduction of features is used. The diagnosis of liver cancer from the computer tomography images is very difficult in nature. Early detection of liver tumor is very helpful to save the human life.

Keywords: computed tomography (CT), multiple region of interest(ROI), feature values, segmentation, SVM classification

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Authors: Amanda de Oliveira Ferreira Leite, Ana Luiza del Pino Ferreira, Bruna Garcez Correa, Janaíne de Souza Mello, Marla Manquevich, Mirna Wetters Portuguez

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Objective: We sought to investigate a neuropsychological intervention focused on improving cognition, psychological aspects, and quality of life of elderly people with mild cognitive impairment. Method: A controlled and randomized study, blind to the evaluator, was executed. We evaluated 78 elderly people, divided into the neuropsychological and control groups, through a semi-structured interview, Addenbrooke’s Cognitive Examination, Katz Index, Lawton and Brody Scale, Geriatric Depression Scale, Beck Anxiety Inventory, Personal Development Scale, WHOQOL-bref and WHOQOL--old. Results: After the intervention, the neuropsychological group showed improvement in the cognitive subtests and in the total score, reduction in the frequency of symptoms associated with anxiety and depression, better psychological well-being, and quality of life. The research highlights useful intervention strategies for improving the general condition of these patients and rehabilitating damaged areas. Conclusion: We concluded that there is a relationship between neuropsychological intervention and improvement in cognitive and psychological performance, as well as in the quality of life in elderly people with mild cognitive impairment.

Keywords: aging, mild cognitive impairment, neuropsychology, quality of life

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Authors: Weerinda Appamana, Jirapong Keawkoon, Yamonporn Pacthong, Jirathiti Chitsanguansuk, Yanyong Sookklay

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In the present work, spinning disc reactor has been used for the intensification of synthesis of biodiesel from refined palm oil (RPO) based on the transesterification reaction. Experiments have been performed using different spinning disc surface and under varying operating parameters viz. molar ratio of oil to methanol (over the range of 1:4.5–1:9), rotational speed (over the range of 500–2,000 rpm), total flow rate (over the range of 260-520 ml/min), and KOH catalyst loading of 1.50% by weight of oil. Maximum FAME (fatty acid methyl esters) yield (97.5 %) of biodiesel from RPO was obtained at oil to methanol ratio of 1:6, temperature of 60 °C, and rotational speed of 1500 rpm and flow rate of 520 mL/min using groove disc at KOH catalyst loading of 1.5 wt%. Also, higher yield efficiency (biodiesel produced per unit energy consumed) was obtained for using the spinning disc reactor based approach as compared to the ultrasound hydrodynamic cavitation and conventional mechanical stirrer reactors. It obviously offers a significant reduction in the reaction time for the transesterification, especially when compared with the reaction time of 90 minutes required for the conventional mechanical stirrer. It can be concluded that the spinning disk reactor is a promising alternative method for continuous biodiesel production.

Keywords: spinning disc reactor, biodiesel, process intensification, yield efficiency

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Authors: Zohreh Rostami, Arezoo Khosravi, Mohammad Nikpoor Aghdam, Mahmood Salesi

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Background: Cardiovascular mortality in chronic kidney disease (CKD) and end stage renal disease (ESRD) patients have a strong relationship with baseline or progressive left ventricular hypertrophy (LVH) meanwhile in hemodialysis patients 10% decrement in left ventricular mass was associated with 28% reduction in cardiovascular mortality risk. In consonance with these arguments, we designed a study to measure morphological and functional echocardiographic variations early after transplantation. Method: The patients with normal renal function underwent two advanced echocardiographic studies to examine the structural and functional changes in left ventricular mass before and 3-month after transplantation. Results: From a total of 23 participants 21(91.3%) presented with left ventricular hypertrophy, 60.9% in eccentric and 30.4% in concentric group. Diastolic dysfunction improved in concentric group after transplantation. Both in pre and post transplantation global longitudinal strain (GLS)- average in eccentric group was more than concentric (-17.45 ± 2.75 vs -14.3 ± 3.38 p=0.03) and (-18.08 ± 2.6 vs -16.1 ± 2.7 p= 0.04) respectively. Conclusion: Improvement and recovery of left ventricular function in concentric group was better and sooner than eccentric after kidney transplantation. Although fractional shortening and diastolic function and GLS-4C in pre-transplantation in concentric group was worse than eccentric, but therapeutic response to kidney transplantation in concentric was more and earlier than eccentric group.

Keywords: chronic kidney disease, end stage renal disease, left ventricular hypertrophy, global longitudinal strain

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Authors: Fatima El Zahra Amin, Emine Efe

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This study was carried out to evaluate the effect of the education program for parents of children with Sickle Cell Anemia, on the knowledge level of parents and the reduction of pain relief by non-pharmacological methods used by parents at home. In Turkey, 54 parents and 109 from Chad agreed to participate in the survey. The data were collected by the researcher using a face-to-face interview method. Non-pharmacological treatment information form for parents, face expressions rating scale, and parent education program for non-pharmacological methods used in children with sickle cell anemia were used. It was determined that there was a statistically significant difference between the educational status, occupation, disease status, place of residence, family structure and age of parents of Chad and Turkey. According to the ratings of facial expressions scale, it was concluded that there was no significant difference between the children’s average degree of pain before and after administration of non-pharmacological methods by the groups of Chad and Turkey. It was determined that the educational programs prepared for parents of children with sickle cell anemia in both Turkey and Chad were effective in increasing the knowledge level of parents and also in reducing pain crisis with non-pharmacological methods parents used at home.

Keywords: Chad, child, non-pharmacological treatment methods, nurse, sickle cell anemia, Turkey

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Authors: Oman Sukmana

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Geographically, Indonesia appears to be disaster-prone areas, whether for natural, nonnatural (man-made), or social disasters. This study aimed to construct the knowledge and social wisdom on the local community in the process of disaster management after the eruption of Mt. Kelud. This study, moreover, encompassed two major concerns: (1) the construction of knowledge and social wisdom on the local community in the process of disaster management after the eruption of Mt. Kelud; (2) the conceptual framework of disaster management on the basis of knowledge and social wisdom on the local community. The study was conducted by means of qualitative approach. The data were analyzed by using the qualitative-descriptive technique. The data collection techniques used in this study were in-depth interview, focus group discussion, observation, and documentation. It was conducted at Pandansari Village, Sub-district Ngantang, District Malang as the most at risk area of Mt. Kelud’s eruption. The purposive sampling was applied ad hoc to select the respondents including: the apparatus of Pandansari Village, the local figures of Pandansari Village, the Chief and Boards of the Forum of Disaster Risk Reduction (FPRB), the Head of Malang Regional Disaster Management Agency, and other agencies. The findings of this study showed that the local community has already possessed the adequate knowledge and social wisdom to overcome the disaster. Through the social wisdom, the local community could predict the potential eruption.

Keywords: knowledge, social and local wisdom, disaster management

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Authors: Linyue Jia, Wenbo Du, Zhaohui Wang, Ke Liu, Shubo Li

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Due to the great potential for weight reduction in aerospace and automotive industries, magnesium-rare earth (Mg-RE) based alloys with outstanding mechanical performance have been widely investigated for decades. However, magnesium alloys are still restricted in engineering applications because of their lower strength and ductility. Hence, there are large spaces and challenges in achieving high-performance Mg alloys. This work reports an Mg-Gd-Er-Zn-Zr alloy with ultrahigh strength and good ductility developed via hot extrusion, pre-deformation, and two-stage aging. The extruded alloy comprises fine dynamically recrystallized (DRXed) grains and coarse worked grains with a large aspect ratio. Pre-deformation has little effect on the microstructure and macro-texture and serves primarily to introduce a large number of dislocations, resulting in strain hardening and higher precipitation strengthening during subsequent aging due to more nucleation sites. As a result, the alloy exhibits a yield strength (YS) of 506 MPa, an ultimate tensile strength (UTS) of 549 MPa, and elongation (EL) of 8.2% at room temperature, showing superior strength-ductility balance than the other wrought Mg-RE alloys previously reported. The current study proposes a combination of pre-deformation and two-stage aging to further improve the mechanical properties of wrought Mg alloys for engineering applications.

Keywords: magnesium alloys, mechanical properties, microstructure, pre-deformation, two-stage aging

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Authors: Femy M. Makkar, S. Chandrakaran, N. Sankar

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The concept of reinforced earth has been used in the field of geotechnical engineering since 1960s, for many applications such as, construction of road and rail embankments, pavements, retaining walls, shallow foundations, soft ground improvement and so on. Conventionally, planar geosynthetic materials such as geotextiles and geogrids were used as the reinforcing elements. Recently, the use of three dimensional reinforcements becomes one of the emerging trends in this field. So, in the present investigation, three dimensional geogrid is proposed as a reinforcing material. Laboratory scaled plate load tests are conducted on a model square footing resting on 3D geogrid reinforced sand bed. The performance of 3D geogrids in triangular and square pattern was compared with conventional geogrids and the improvement in bearing capacity and reduction in settlement and heave are evaluated. When single layer of reinforcement was placed at an optimum depth of 0.25B from the bottom of the footing, the bearing capacity of conventional geogrid reinforced soil improved by 1.85 times compared to unreinforced soil, where as 3D geogrid reinforced soil with triangular pattern and square pattern shows 2.69 and 3.05 times improvement respectively compared to unreinforced soil. Also, 3D geogrids performs better than conventional geogrids in reducing the settlement and heave of sand bed around the model footing.

Keywords: 3D reinforcing elements, bearing capacity, heavy, settlement

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Authors: Utsamani Cintyamena, Sandra Frans Olivia, Shita Lisyadewi, Ariane Utomo

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Family planning is one of fundamental aspects in preventing maternal morbidity and mortality. However, the prevalence rate of Indonesia’s married women in choosing contraception is low. This study purpose to assess opportunities and challenges in family planning. Methodology: We conducted a qualitative study in Banyumas District which has huge reduction of maternal mortality rate from 2013 to 2015. Four focus group discussions and four small group discussions were conducted to assess knowledge and attitude of women in using contraceptive and their method of choice, as well as in-depth interview to four health workers and two family planning field officers as triangulation. Thematic content analysis was done manually. Results: Key themes emerge across interviews including (1) first choice of contraception is the one that they previously had, provided that they did not encountered problems with it, (2) rumor and fear of side effect affected their method of choice, (3) selection of contraceptive method was influenced by approval of husband, believes, and role model in community. Conclusion: Collaboration of health worker, family planning field officers, community, as well as support from stakeholder, must be increased to socializing family planning.

Keywords: attitude, challenge, chance, family planning, knowledge

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Authors: Kathryn H. Yull, Lina T. Al Kury, Frank Christopher Howarth

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Cardiovascular diseases are frequently reported in patients with Type-1 Diabetes mellitus (DM). In addition to changes in cardiac muscle inotropy, electrical abnormalities are also commonly observed in these patients. In the present study, using streptozotocin (STZ) rat model of Type-1 DM, we have characterized the changes in L-type calcium channel activity in single atrioventricular nodal (AVN) myocytes. Ionic currents were recorded from AVN myocytes isolated from the hearts of control rats and from those with STZ-induced diabetes. Patch-clamp recordings were used to assess changes in cellular electrical activity in individual myocytes. Type-1 DM significantly altered the cellular characteristics of L-type calcium current (ICaL). A reduction in peak ICaL density was observed, with no corresponding changes in the activation parameters of the current. ICaL also exhibited faster time-dependent inactivation in AVN myocytes from diabetic rats. A negative shift in the voltage dependence of inactivation was also evident. These findings demonstrate that experimentally–induced type-1 DM significantly alters AVN L-type calcium channel cellular electrophysiology. The changes in ion channel activity may underlie the abnormalities in the cardiac electrical function that contribute to the high mortality levels in patients with DM.

Keywords: cardiac, ion-channel, diabetes, atrioventricular node, calcium channel

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Authors: Abdullah AlGhazali, Richard Fairchild, Yilmaz Guney

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We examine the effect of managerial overconfidence on UK firms’ payout policy for the period 2000 to 2012. The analysis incorporates, in addition to common firm-specific factors, a wide range of corporate governance factors and managerial characteristics that have been documented to affect the relationship between overconfidence and payout policy. Our results are robust to several estimation considerations. The findings show that the influence of overconfident CEOs on the amount of, and the propensity to pay, dividends is significant within the UK context. Specifically, we detect that there is a reduction in dividend payments in firms managed by overconfident managers compared to their non-overconfident counterparts. Moreover, we affirm that cash flows, firm size and profitability are positively correlated, while leverage, firm growth and investment are negatively correlated with the amount of and propensity to pay dividends. Interestingly, we demonstrate that firms with the potential for undervaluation reduce dividend payments. Some of the corporate governance factors are shown to motivate firms to pay more dividends while these factors seem to have no influence on the propensity to pay dividends. The results also show that in general higher overconfidence leads to more share repurchases but the lower total payout. Overall, managerial overconfidence should be considered as an important factor influencing payout policy in addition to other known factors.

Keywords: dividends, repurchases, UK firms, overconfidence, corporate governance, undervaluation

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Authors: Anurakti Shukla, Sudhakar Srivastava

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Cyanobacteria are known for rapid growth rates, high biomass, and the ability to accumulate potentially toxic elements and contaminants. The present work was planned to develop a low-cost, feasible prototype, CyanoClean, for the growth of a cyanobacterial consortium for the removal of arsenic (As) from water. The cyanobacterial consortium consisting of Oscillatoria, Phormidiumand Gloeotrichiawas used, and the conditions for optimal growth of the consortium were standardized. A pH of 7.6, initial cyanobacterial biomass of 10 g/L, and arsenite [As(III)] and arsenate [As(V)] concentration of 400 μΜand 600 μM, respectively, were found to be suitable. The CyanoClean prototype was designed with acrylic sheet and had arrangements for optimal cyanobacterial growth in natural sunlight and also in artificial light. The As removal experiments in concentration- and duration-dependent manner demonstrated removal of up to 39-69% and 9-33% As respectively from As(III) and As(V)-contaminated water. In field testing of CyanoClean, natural As-contaminated groundwater was used, and As reduction was monitored when a flow rate of 3 L/h was maintained. In a field experiment, As concentration in groundwater was found to reduce from 102.43 μg L⁻¹ to <10 μg L⁻¹ after 6 h in natural sunlight. However, in shaded conditions under artificial light, the same result was achieved after 9 h. The CyanoClean prototype is of simple design and can be easily up-scaled for application at a small- to medium-size land and shall be affordable even for a low- to middle-income group farmer.

Keywords: cyanoclean, gloeotrichia, oscillatoria, phormidium, phycoremediation

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Authors: Endalamaw Ewnu Kassa, Ade Kurniawan, Ya-Fen Wu, Sajal Biring

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Perovskite-based gas sensors represent a highly promising materials within the realm of gas sensing technology, with a particular focus on detecting ammonia (NH3) due to its potential hazards. Our work conducted thorough comparison of various solvents, including dimethylformamide (DMF), DMF-dimethyl sulfoxide (DMSO), dimethylacetamide (DMAC), and DMAC-DMSO, for the preparation of our perovskite solution (MAPbI3). Significantly, we achieved an exceptional response at 10 ppm of ammonia gas by employing a binary solvent mixture of DMAC-DMSO. In contrast to prior reports that relied on single solvents for MAPbI3 precursor preparation, our approach using mixed solvents demonstrated a marked improvement in gas sensing performance. We attained enhanced surface coverage, a reduction in pinhole occurrences, and precise control over grain size in our perovskite films through the careful selection and mixtures of appropriate solvents. This study shows a promising potential of employing binary and multi-solvent mixture strategies as a means to propel advancements in gas sensor technology, opening up new opportunities for practical applications in environmental monitoring and industrial safety.

Keywords: sensors, binary solvents, ammonia, sensitivity, grain size, pinholes, surface coverage

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Authors: Mária Hudáková, Mária Lusková

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This report is focused on widening the theoretical knowledge as well as controlling practical application from the risk management point of view, regarding to dynamic business changes that have occurred in Slovakia which recently has been considered to be an environment full of risk and uncertainty. The idea of the report is the proposal of the controlling operation model in the course of risk management process in an enterprise operating in Slovakia, by which the controller is able to identify early risk factors in suggested major areas of the business management upon appropriate business information integration, consecutive control and prognoses and to prepare in time full-value documents in order to suggest measures for reduction thereof. Dealing with risk factors, that can quickly limit the growth potential of the enterprise, is an essential part of managerial activities on each level. This is the reason why mutual unofficial, ergo collegial cooperation of individual departments is necessary for controlling application from the business risk management point of view. An important part of the report is elaborated survey of the most important risk factors existing in major management areas of enterprises operating in Slovakia. The outcome of the performed survey is a catalogue of the most important enterprise risk factors. The catalogue serves for better understanding risk factors affecting the Slovak enterprises, their importance and evaluation.

Keywords: controlling, information, risks, risk factor, crisis

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Authors: Babatunde Johnson

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The rate of diseases and death from preventable diseases among ethnic minority groups is high when compared with the wider white population in the UK. This can be due in part to the diet consumed and various cultural reasons. Changes in dietary practices and the health of ethnic minority groups can be caused by the adoption of food practices of the host culture after migration (acculturation) and generational differences among migrants. However, understanding how and why these changes occur is limited due to the challenges of data collection in research. This research utilizes the interpretive phenomenological approach, coupled with Bourdieu’s theory used as the conceptual framework, and seeks an in-depth understanding of how adult immigrant Nigerians in the UK interpret their experience of the influence of ethnic and prevailing cultures on their dietary practice. Recruiting participants from a close-knit community, such as the Nigerian population in the UK, can be complex and problematic and is determined by the accessibility to the community. Although complex, the researcher leveraged the principles of Patient and Public Involvement (PPI) in gaining access to participants within the Nigerian community. This study emphasizes the need for a culturally tailored and community-centered approach to interventions geared toward the reduction of ethnic health inequality in the UK other than the existing practice, which focuses on better healthy eating through the improvement of skills and knowledge about food groups.

Keywords: culture, dietary practice, ethnic minority, health inequality

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Authors: Talakokula Visalakshi

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Concrete is the most commonly used construction material across the globe, its usage is second only to water. It is prepared using ordinary Portland cement whose production contributes to 5-8% of total carbon emission in the world. On the other hand the fly ash by product from the power plants is produced in huge quantities is termed as waste and disposed in landfills. In order to address the above issues mentioned, it is essential that other forms of binding material must be developed in place of cement to make concrete. The geo polymer concrete is one such alternative developed by Davidovits in 1980’s. Geopolymer do not form calcium-silicate hydrates for matrix formation and strength but undergo polycondensation of silica and alumina precursors to attain structural strength. Its setting mechanism depends upon polymerization rather than hydration. As a result it is able to achieve its strength in 3-5 days whereas concrete requires about a month to do the same. The objective of this research is to assess the performance of geopolymer concrete under sulphate and acid attack. The assessment is done based on the experiments conducted on geopolymer concrete. The expected outcomes include that if geopolymer concrete is more durable than normal concrete, then it could be a competitive replacement option of concrete and can lead to significant reduction of carbon foot print and have a positive impact on the environment. Fly ash based geopolymer concrete offers an opportunity to completely remove the cement content from concrete thereby making the concrete a greener and future construction material.

Keywords: fly ash, geo polymer, geopolymer concrete, construction material

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Authors: Eric S. Lee, Connie Bygrave, Jordan Mahar, Naina Garg, Suzanne Cottreau

Abstract:

Marking exams is universally detested by lecturers. Final exams in many higher education courses often last 3.0 hrs. Do exams really need to be so long? Can we justifiably reduce the number of questions on them? Surprisingly few have researched these questions, arguably because of the complexity and difficulty of using traditional methods. To answer these questions empirically, we used a new approach based on three key elements: Use of an unusual variation of a true experimental design, equivalence hypothesis testing, and an expanded set of six psychometric criteria to be met by any shortened exam if it is to replace a current 3.0-hr exam (reliability, validity, justifiability, number of exam questions, correspondence, and equivalence). We compared student performance on each official 3.0-hr exam with that on five shortened exams having proportionately fewer questions (2.5, 2.0, 1.5, 1.0, and 0.5 hours) in a series of four experiments conducted in two classes in each of two finance courses (224 students in total). We found strong evidence that, in these courses, shortening of final exams to 2.0 hrs was warranted on all six psychometric criteria. Shortening these exams by one hour should result in a substantial one-third reduction in lecturer time and effort spent marking, lower student stress, and more time for students to prepare for other exams. Our approach provides a relatively simple, easy-to-use methodology that lecturers can use to examine the effect of shortening their own exams.

Keywords: exam length, psychometric criteria, synthetic experimental designs, test length

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Authors: Fatima Babar, Majid I. Khan, Malik Najmus Saqib, Muhammad Tahir

Abstract:

This article provides range based improvements over a well-known single-hop range free localization scheme, Approximate Point in Triangulation (APIT) by proposing an energy efficient Barycentric coordinate based Point-In-Triangulation (PIT) test along with PIT based trilateration. These improvements result in energy efficiency, reduced localization error and improved localization coverage compared to APIT and its variants. Moreover, we propose to embed Received signal strength indication (RSSI) based distance estimation in DV-Hop which is a multi-hop localization scheme. The proposed localization algorithm achieves energy efficiency and reduced localization error compared to DV-Hop and its available improvements. Furthermore, a hybrid multi-hop localization scheme is also proposed that utilize Barycentric coordinate based PIT test and both range based (Received signal strength indicator) and range free (hop count) techniques for distance estimation. Our experimental results provide evidence that proposed hybrid multi-hop localization scheme results in two to five times reduction in the localization error compare to DV-Hop and its variants, at reduced energy requirements.

Keywords: Localization, Trilateration, Triangulation, Wireless Sensor Networks

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Authors: Saurabh Sharma, Yong Sun, Bruce Vernham

Abstract:

Accurate prediction of NOx emission is a continuous challenge in the field of diesel engine-out emission modeling. Performing experiments for each conditions and scenario cost significant amount of money and man hours, therefore model-based development strategy has been implemented in order to solve that issue. NOx formation is highly dependent on the burn gas temperature and the O₂ concentration inside the cylinder. The current empirical models are developed by calibrating the parameters representing the engine operating conditions with respect to the measured NOx. This makes the prediction of purely empirical models limited to the region where it has been calibrated. An alternative solution to that is presented in this paper, which focus on the utilization of in-cylinder combustion parameters to form a predictive semi-empirical NOx model. The result of this work is shown by developing a fast and predictive NOx model by using the physical parameters and empirical correlation. The model is developed based on the steady state data collected at entire operating region of the engine and the predictive combustion model, which is developed in Gamma Technology (GT)-Power by using Direct Injected (DI)-Pulse combustion object. In this approach, temperature in both burned and unburnt zone is considered during the combustion period i.e. from Intake Valve Closing (IVC) to Exhaust Valve Opening (EVO). Also, the oxygen concentration consumed in burnt zone and trapped fuel mass is also considered while developing the reported model.  Several statistical methods are used to construct the model, including individual machine learning methods and ensemble machine learning methods. A detailed validation of the model on multiple diesel engines is reported in this work. Substantial numbers of cases are tested for different engine configurations over a large span of speed and load points. Different sweeps of operating conditions such as Exhaust Gas Recirculation (EGR), injection timing and Variable Valve Timing (VVT) are also considered for the validation. Model shows a very good predictability and robustness at both sea level and altitude condition with different ambient conditions. The various advantages such as high accuracy and robustness at different operating conditions, low computational time and lower number of data points requires for the calibration establishes the platform where the model-based approach can be used for the engine calibration and development process. Moreover, the focus of this work is towards establishing a framework for the future model development for other various targets such as soot, Combustion Noise Level (CNL), NO₂/NOx ratio etc.

Keywords: diesel engine, machine learning, NOₓ emission, semi-empirical

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Authors: John Wangui, Charles Gachene, Stephen Mureithi, Boniface Kiteme

Abstract:

Land use changes caused by demographic, natural variability, economic, technological and policy factors affect the goods and services derived from an ecosystem. In the past few decades, Lake Ol Bolossat catchment in Nyandarua County Kenya has been facing challenges of land cover changes threatening its capacity to perform ecosystems functions and adversely affecting communities and ecosystems downstream. This study assessed land cover changes in the catchment for a period of twenty eight years (from 1986 to 2014). Analysis of three Landsat images i.e. L5 TM 1986, L5 TM 1995 and L8 OLI/TIRS 2014 was done using ERDAS 9.2 software. The results show that dense forest, cropland and area under water increased by 27%, 29% and 3% respectively. On the other hand, open forest, dense grassland, open grassland, bushland and shrubland decreased by 3%, 3%, 11%, 26% and 1% respectively during the period under assessment. The lake was noted to have increased due to siltation caused by soil erosion causing a reduction in Lake’s depth and consequently causing temporary flooding of the wetland. The study concludes that the catchment is under high demographic pressure which would lead to resource use conflicts and therefore formulation of mitigation measures is highly recommended.

Keywords: land cover, land use change, land degradation, Nyandarua, Remote sensing

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Authors: Igor Michel Gachig, Samanta Tiague

Abstract:

Baka ‘Pygmies’ is an indigenous community living in the rainforest region of Cameroon. This community is known to be poor and marginalized from the political, economic and social life, regardless of sedentarization and development efforts. In fact, the social exclusion of ‘Pygmy’ people prevents them from gaining basic citizen’s rights, among which access to education, land, healthcare, employment and justice. In this study, social interactions, behaviors, and perceptions were considered. An interview guide and focus group discussions were used to collect data. A sample size of 97 was used, with 60 Baka Pygmies and 37 Bantus from two Baka-Bantu settlements/villages of the south region of Cameroon. The data were classified in terms of homogenous, exhaustive and exclusive categories. This classification has enabled factors explaining social exclusion in the Baka community to be highlighted using content analysis. The study shows that (i) limited access to education, natural resources and care in modern healthcare organizations, and (ii) different views on the development expectations and integration approaches both highlight the social exclusion in the Baka ‘Pygmies’ community. Therefore, an effective and adequate social integration of ‘Pygmies’ based on cultural peculiarities and identity, as well as reduction of disparities and improvement of their access to education should be of major concern to the government and policy makers.

Keywords: development, indigenous people, integration, social exclusion

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