Search results for: fuel rate

Authors: Akuélé Radha Kondo, Kathrin Heitz-Tokpa, Bassirou Bonfoh, Francis Akindes

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Postgraduate supervision contributes significantly to a student’s academic career, a supervisor’s promotion, and a university’s reputation. Despite this, the length of graduation in the Côte d’Ivoire University system is beyond the normal duration, two years for a master's and three years for a PhD. The paper analyses supervision practices regarding the challenges and strategies mobilised by students, supervisors, and administration staff to manage various relationships. Using a qualitative research design, this study was conducted at three public universities in Côte d’Ivoire. Data were generated from thirty-two postgraduate students, seventeen supervisors, and four administration staff through semi-structured interviews. Data were analysed using content analysis and presented thematically. Findings revealed delegated supervision and co-supervision, two types of supervision relationship practices. Students pointed out that feedback is often delayed from their supervisors in delegation supervision. However, they acknowledged receiving input and scientific guidance. All students believed that their role is to be proactive, not to wait to receive everything from the supervisor, and need to be more autonomous and hardworking. They developed strategies related to these qualities. Supervisors were considered to guide, give advice, control, motivate, provide critical feedback, and validate the work. The administration was rather absent in monitoring supervision delays. Major challenges were related to the supervision relationships and access to the research funds. The study showed that more engagement of the main supervisor, administration monitoring, and secured funding would reduce the time and increase the completion rate.

Keywords: Côte d’Ivoire, postgraduate supervision, practices, strategies

Procedia PDF Downloads 84

Authors: Ashit Syngle, Inderjit Verma, Pawan Krishan

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Objective: Endothelial progenitor cells (EPCs) have reparative potential in overcoming the endothelial dysfunction and reducing cardiovascular risk. EPC depletion has been demonstrated in the setting of established atherosclerotic diseases. With this background, we evaluated whether reduced EPCs population are associated with endothelial dysfunction, subclinical atherosclerosis and inflammatory markers in ankylosing spondylitis (AS) patients without any known traditional cardiovascular risk factor in AS patients. Methods: Levels of circulating EPCs (CD34+/CD133+), brachial artery flow-mediated dilatation, carotid intima-media thickness (CIMT) and inflammatory markers i.e erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), tissue necrosis factor (TNF)–α, interleukin (IL)-6, IL-1 were assessed in 30 AS patients (mean age33.41 ± 10.25; 11 female and 19 male) who fulfilled the modified New York diagnostic criteria with 25 healthy volunteers (mean age 29.36± 8.64; 9 female and 16 male) matched for age and sex. Results: EPCs (CD34+/CD133+) cells were significantly (0.020 ± 0.001% versus 0.040 ± 0.010%, p<0.001) reduced in patients with AS compared to healthy controls. Endothelial function (7.35 ± 2.54 versus 10.27 ±1.73, p=0.002), CIMT (0.63 ± 0.01 versus 0.35 ± 0.02, p < 0.001) and inflammatory markers were also significantly (p < 0.01) altered as compared to healthy controls. Specifically, CD34+CD133+cells were inversely multivariate correlated with CRP and TNF-α and endothelial dysfunction was positively correlated with reduced number of EPC. Conclusion: Depletion of EPCs population is an independent predictor of endothelial dysfunction and early atherosclerosis in AS patients and may provide additional information beyond conventional risk factors and inflammatory markers.

Keywords: endothelial progenitor cells, atherosclerosis, ankylosing spondylitis, cardiovascular

Procedia PDF Downloads 372

Authors: Anoff Anim, Lila Mahmoud, Maria Katsikogianni, Sanjit Nayak

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Sustained and controlled delivery of antimicrobial drugs have been largely studied recently using metal organic frameworks (MOFs)and different polymers. However, much attention has not been given to combining both MOFs and biodegradable polymers, which would be a good strategy in providing a sustained gradual release of the drugs. Herein, we report a comparative study of the sustained and controlled release of widely used antibacterial drugs, cephalexin and metronidazole, from zinc-based MOF-5 incorporated in biodegradable polycaprolactone (PCL) and poly-lactic glycolic acid (PLGA) membranes. Cephalexin and metronidazole were separately incorporated in MOF-5 post-synthetically, followed by their integration into biodegradable PLGA and PCL membranes. The pristine MOF-5 and the loaded MOFs were thoroughly characterized by FT-IR, SEM, TGA and PXRD. Drug release studies were carried out to assess the release rate of the drugs in PBS and distilled water for up to 48 hours using UV-Vis Spectroscopy. Four bacterial strains from both the Gram-positive and Gram-negative types, Staphylococus aureus, Staphylococuss epidermidis, Escherichia coli, Acinetobacter baumanii, were tested against the pristine MOF, pure drugs, loaded MOFs and the drug-loaded MOF-polymer composites. Metronidazole-loaded MOF-5 composite of PLGA (PLGA-Met@MOF-5) was found to show highest efficiency to inhibit the growth of S. epidermidis compared to the other bacteria strains while maintaining a sustained minimum inhibitory concentration (MIC). This study demonstrates that the combination of biodegradable MOF-polymer composites can provide an efficient platform for sustained and controlled release of antimicrobial drugs and can be a potential strategy to integrate them in biomedical devices.

Keywords: antimicrobial resistance, biodegradable polymers, cephalexin, drug release metronidazole, MOF-5, PCL, PLGA

Procedia PDF Downloads 119

Authors: Ramūnas Antanaitis, Lina Anskienė, Robertas Stoškus

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This study was conducted during 2021.05.01 – 2021.08.31 at the Lithuanian University of health sciences and one Lithuanian dairy farm with 500 dairy cows (55.911381565736, 21.881321760608195). Average calving – 50 cows per month. Cows (n=20) in the treatment group (TG) were fed with feed supplement Optipartum C+ 200 (Enzymes: Alfa- Amylase 57 Units; Beta-Glucanase 107 Units) from 21 days before calving till 30 days after calving with feeding rate 200g/cow/day. Cows in the control group (CG) were fed a feed ration without feed supplement. Measurements started from 6 days before calving and continued till 21 days after calving. The following indicators were registered: with the RumiWatch System: Rumination time; Eating time; Drinking time; Rumination chews; Eating chews; Drinking gulps; Bolus; Chews per minute; Chews per bolus. With SmaXtec system - the temperature, pH of the contents of cows' reticulorumens and cows' activity. According to our results, we found that feeding of cows, from 21 days before calving to 30 days after calving, with a feed supplement with alfa- amylase and beta-glucanase (Optipartum C+ 200) (with dose 200g/cow/day) can produce an increase in: 9% rumination time and eating time, 19% drinking time, 11% rumination chews, 16% eating chews,13% number of boluses per rumination, 5% chews per minute and 16% chews per bolus. We found 1.28 % lower reiticulorumen pH and 0.64% lower reticulorumen temperature in cows fed with the supplement compared with control group cows. Also, cows feeding with enzymes were 8.80% more active.

Keywords: Alfa-Amylase, Beta-Glucanase, cows, in-line, sensors

Procedia PDF Downloads 306

Authors: Rafat Rob, Khaled Alotaibi, Dana Nour, Abdullah Albadrani, Abdulmohsen Mulhim

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Power systems digitization solutions provides a comprehensive smart, cohesive, interconnected network, extensive connectivity between digital assets, physical power plants, and resources to form digital economies. However, digitization has exposed the classical air gapped power plants to the rapid spread of cyber threats and attacks in the process delaying and forcing many organizations to rethink their cyber security policies and standards before they can augment their operation the new advanced digital devices. Cyber Security requirements for power systems (and industry control systems therein) demand a new approach, unique methodology, and design process that is completely different to Cyber Security measures designed for the IT systems. In practice, Cyber Security strategy, as applied to power systems, tends to be closely aligned to those measures applied for IT system purposes. The differentiator for Cyber Security in terms of power systems are the physical assets and applications used, alongside the ever-growing rate of expansion within the industry controls sector (in comparison to the relatively saturated growth observed for corporate IT systems). These factors increase the magnitude of the cyber security risk within such systems. The introduction of smart devices and sensors along the grid initiate vulnerable entry points to the systems. Every installed Smart Meter is a target; the way these devices communicate with each other may instigate a Denial of Service (DoS) and Distributed Denial of Service (DDoS) attack. Attacking one sensor or meter has the potential to propagate itself throughout the power grid reaching the IT network, where it may manifest itself as a malware infiltration.

Keywords: supply chain, cybersecurity, maturity model, risk, smart grid

Procedia PDF Downloads 92

Authors: Rita Yuniatun, Dewi Fadlilah Firdausi, Anida Hanifah, Putrisuvi Nurjannah Zalqis, Erza Nur Afrilia, Akrima Fajrin Nurimani, Andrew Luis Krishna

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Manganese (Mn) is one of the potential contaminants minerals geothermal water. Preliminary studies conducted in Ketenger village, the nearest village with Baturaden hot spring, showed that the concentration of Mn in water supply has exceeded the reference value. Mineral contamination problem in Ketenger village is not only Mn, but also other potential geothermal minerals, such as chromium (Cr), iron (Fe), sulfide (S2-), nickel (Ni), cobalt (Co), and zinc (Zn). It becomes a concern because generally the residents still use ground water as the water source for their daily needs, including drinking and cooking. Therefore, this study aimed to determine the distribution of mineral contamination in drinking water and food and to estimate the health risks possibility from the exposure. Four minerals (Mn, Fe, S2-, and Cr6+) were analyzed in drinking water, carbohydrate sources, vegetables, fishes, and fruits. The test results indicate that Mn concentration in drinking water is 0.35 mg/L, has exceeded the maximum contaminant level (MCL) according to the US EPA (MCL = 0.005 mg/L), whereas other minerals still comply with the standards. In addition, we found that the average of Mn concentration in the carbohydrate sources is quite high (1.87 mg/Kg). Measurement results in Chronic Daily Intake (CDI) and the Risk Quotient (RQ) found that exposure to manganese and other geothermal minerals in drinking water and food are safe from the non-carcinogenic effects in each age group (RQ<1). So, geothermal mineral concentrations in drinking water and food has no effect on non-carcinogenic risk in Ketenger’s residents because of CDI is also influenced by other parameters such as the duration of exposure and the rate of consumption. However, it was found that intake of essential minerals (Mn and Fe) are deficient in every age group. So that, the addition of Mn and Fe intake is recommended.

Keywords: CDI, contaminant, geothermal minerals, manganese, RQ

Procedia PDF Downloads 253

Authors: Javier Paul Montalvo Andia, Adriana Larrea Valdivia, Adolfo Pillihuaman Zambrano

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The most common lixiviant in the leaching process of copper minerals is H₂SO₄, however, the current situation requires more environmentally friendly reagents and in certain situations that have a lower consumption due to the presence of undesirable gangue as muscovite or kaolinite that can make the process unfeasible. The present work studied the leaching of an oxidized copper mineral in an aqueous solution of ammonium nitrate, in order to obtain the optimum leaching conditions of the copper contained in the malachite mineral from Peru. The copper ore studied comes from a deposit in southern Peru and was characterized by X-ray diffractometer, inductively coupled-plasma emission spectrometer (ICP-OES) and atomic absorption spectrophotometry (AAS). The experiments were developed in batch reactor of 600 mL where the parameters as; temperature, pH, ammonium nitrate concentration, particle size and stirring speed were controlled according to experimental planning. The sample solution was analyzed for copper by atomic absorption spectrophotometry (AAS). A simulation in the HSC Chemistry 6.0 program showed that the predominance of the copper compounds of a Cu-H₂O aqueous system is altered by the presence in the system of ammonium complexes, the compound being thermodynamically more stable Cu(NH3)₄²⁺, which predominates in pH ranges from 8.5 to 10 at a temperature of 25 °C. The optimum conditions for copper leaching of the malachite mineral were a stirring speed of 600 rpm, an ammonium nitrate concentration of 4M, a particle diameter of 53 um and temperature of 62 °C. These results showed that the leaching of copper increases with increasing concentration of the ammonium solution, increasing the stirring rate, increasing the temperature and decreasing the particle diameter. Finally, the recovery of copper in optimum conditions was above 80%.

Keywords: ammonium nitrate, malachite, copper oxide, leaching

Procedia PDF Downloads 176

Authors: Yogi Sirodz Gaos, Irvan Wiradinata

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In the 500 kW Organic Rankine Cycle (ORC) power plant in Indonesia, an AFT (according to the Tubular Exchanger Manufacturers Association – TEMA) type shell and tube heat exchanger device is used as a pre-heating system for the ORC’s hot water circulation system. The pre-heating source is a waste heat recovery of the brine water, which is tapped from a geothermal power plant. The brine water itself has 5 MWₜₕ capacities, with average temperature of 170ᵒC, and 7 barg working pressure. The aim of this research is to examine the performance of the heat exchanger in the ORC system in a 500 kW ORC power plant. The data for this research were collected during the commissioning on the middle of December 2016. During the commissioning, the inlet temperature and working pressure of the brine water to the shell and tube type heat exchanger was 149ᵒC, and 4.4 barg respectively. Furthermore, the ΔT for the hot water circulation of the ORC system to the heat exchanger was 27ᵒC, with the inlet temperature of 140ᵒC. The pressure in the hot circulation system was dropped slightly from 7.4ᵒC to 7.1ᵒC. The flow rate of the hot water circulation was 80.5 m³/h. The presentation and discussion of a case study on the performance of the heat exchanger on the 500 kW ORC system is presented as follows: (1) the heat exchange duty is 2,572 kW; (2) log mean temperature of the heat exchanger is 13.2ᵒC; (3) the actual overall thermal conductivity is 1,020.6 W/m².K (4) the required overall thermal conductivity is 316.76 W/m².K; and (5) the over design for this heat exchange performance is 222.2%. An analysis of the heat exchanger detailed engineering design (DED) is briefly discussed. To sum up, this research concludes that the shell and tube heat exchangers technology demonstrated a good performance as pre-heating system for the ORC’s hot water circulation system. Further research need to be conducted to examine the performance of heat exchanger system on the ORC’s hot water circulation system.

Keywords: shell and tube, heat exchanger, organic Rankine cycle, performance, commissioning

Procedia PDF Downloads 132

Authors: Hameed Ullah, Karim Elakabawi, Han KE, Najeeb Ullah, Habib Ullah, Sardar Ali Shah, Hamad Haider Khan, Muhammad Asad Khan, Ning Guo, Zuyi Yuan

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Background: Predictors of decreased fractional flow reserve at left circumflex coronary artery after left main (LM) crossover stenting are still lacking. The objectives of the present study were to provide the predictors for low Fractional flow reserve (FFR) at coronary artery (LCx) and the possible treatment strategies for the compromised LCx-together with their long term outcomes. Methods: A total of 563 included patients out of 1974 patients admitted to our hospital from February 2015 to November 2020 with significant distal LM-bifurcation lesions. The enrolled patients underwent single-stent cross-over PCI under IVUS guidance with further LCx intervention as indicated by measured FFR. Results: The included patients showed angiographic significant LCx ostial affection after LM-stenting, but only 116 (20.6%) patients had FFR <0.8. The 3-year composite MACE rates were comparable between the high and low FFR groups (16.8% vs. 15.5%, respectively; P=0.744). In a multivariable analysis, a low FFR in the LCx was associated with post-stenting MLA of the LCx (OR: 0.032, P <0.001), post-stenting LCx-plaque burden (OR: 1.166, P <0.001), post-stenting LM-MLA (OR: 0.821, P =0.038) and pre-stenting LCx-MLA (OR: 0.371, P =0.044). In patients with low FFR, management of compromised LCx with DEB had the lowest 3-year MACE rate (8.1%) as compared to either KBI (17.5%) or stenting group (20.5%), P =0.299. Conclusion: FFR-guided LCx intervention can avoid unnecessary LCx intervention. The post-stenting predictors of low FFR include post-stenting MLA and plaque burden of the LCx and MV stent length. The 3-year MACE rates were comparable between high FFR patients and patients who had low FFR and were adequately managed.

Keywords: fractional flow reserve, left main stem, percutaneous coronary interventions, intravascular ultrasound

Procedia PDF Downloads 25

Authors: Fellah Sihem

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The optimal use of soil moisture by culture, is related to the leaf area index, which stood in the cycle and its modulation according to the prevailing stress intensity. For a given stock of water in the soil, cultivar adapted and saving water is one that is no luxury consumption during the preanthesis. It modulates the leaf area index to regulate sweating in the degree of its water supply. In plants water saving, avoidance of dehydration is related to the reduction of water loss by cuticular and stomatal pathways. Muchow and Sinclair reported that the test of relative water content (TRE) is considered the best indicator of leaf water status. The search for indicators of the ability of the plant to make good use of the water, under water stress is a prerequisite for progress in improving performance under water stress. This experiment aims to characterize a set of durum wheat varieties, tested jars and vegetation under different levels of water stress to the surface of the leaf, relative water content, cell integrity, the accumulated biomass and efficiency of water use. The experiment was conducted during the 2005/2006 academic year, at the Agricultural Research Station of the Field Crop Institute of Setif, under semi-controlled conditions. Five genotypes of durum wheat (Triticum durum Desf) were evaluated for their ability to tolerate moderate and severe water stress. The results showed that geno types respond differently to water stress. Dry matter accumulation and growth rate varied among geno types and were significantly reduced. At severe water stress biomass accumulated by Boussalam was the least affected.

Keywords: water stress, triticum durum, biomass, cell membrane integrity, relative water content

Procedia PDF Downloads 456

Authors: Adilah Shariff, Nur Syairah Mohamad Aziz, Norsyahidah Md Saleh, Nur Syuhada Izzati Ruzali

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The first objective of this study is to investigate the suitability of coconut frond (CF) and coconut husk (CH) as feedstocks using a laboratory-scale slow pyrolysis experimental setup. The second objective is to investigate the effect of pyrolysis temperature on the biochar yield. The properties of CF and CH feedstocks were compared. The properties of the CF and CH feedstocks were investigated using proximate and elemental analysis, lignocellulosic determination, and also thermogravimetric analysis (TGA). The CF and CH feedstocks were pyrolysed at 300, 400, 500, 600 and 700 °C for 2 hours at 10 °C/min heating rate. The proximate analysis showed that CF feedstock has 89.96 mf wt% volatile matter, 4.67 mf wt% ash content and 5.37 mf wt% fixed carbon. The lignocelluloses analysis showed that CF feedstock contained 21.46% lignin, 39.05% cellulose and 22.49% hemicelluloses. The CH feedstock contained 84.13 mf wt% volatile matter, 0.33 mf wt% ash content, 15.54 mf wt% fixed carbon, 28.22% lignin, 33.61% cellulose and 22.03% hemicelluloses. Carbon and oxygen are the major component of the CF and CH feedstock compositions. Both of CF and CH feedstocks contained very low percentage of sulfur, 0.77% and 0.33%, respectively. TGA analysis indicated that coconut wastes are easily degraded. It may be due to their high volatile content. Between the temperature ranges of 300 and 800 °C, the TGA curves showed that the weight percentage of CF feedstock is lower than CH feedstock by 0.62%-5.88%. From the D TGA curves, most of the weight loss occurred between 210 and 400 °C for both feedstocks. The maximum weight loss for both CF and CH are 0.0074 wt%/min and 0.0061 wt%/min, respectively, which occurred at 324.5 °C. The yield percentage of both CF and CH biochars decreased significantly as the pyrolysis temperature was increased. For CF biochar, the yield decreased from 49.40 wt% to 28.12 wt% as the temperature increased from 300 to 700 °C. The yield for CH biochars also decreased from 52.18 wt% to 28.72 wt%. The findings of this study indicated that both CF and CH are suitable feedstock for slow pyrolysis of biochar.

Keywords: biochar, biomass, coconut wastes, slow pyrolysis

Procedia PDF Downloads 195

Authors: Baboo Ali, Avni Ugur

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Pesticide namely, Diflubenzuron, is tremendously used in pear orchards against different insect pests of pear fruit trees in Turkey. The predatory bug, Anthocoris nemoralis (F.) is found in pear orchard feeding on Cacopsylla pyri (L.) (Homoptera: Psyllidae), is an insect pest of pear fruit trees. In this study, the effectiveness of the above mentioned pesticide on various biological stages of predatory bug were investigated under laboratory conditions of 25±1˚C, 75±5% RH, and photoperiod of 16L: 8D h. Newly emerged 1st, 2nd, 3rd, 4th and 5th instars as well as the female and male stages of the predatory bug were placed on treated petri dishes and their mortality was checked after every 24 hours till the survival of the last individual. Prey consumption of surviving instars as well as the adult stages was determined simultaneously. All biological stages of the predatory bug were fed with eggs of Ephestia kuehniella during the whole research work. Percent hatch of treated eggs was recorded after every 24 hours, and the behavioral test of the male and female stages against Diflubenzuron was also determined using Y-tube olfactometer. Consequently, the mortality rate of 1st, 2nd, 3rd, 4th, and 5th instars was 61.32 %, 67.50%, 74. 91%, 80.11%, and 83.04%, respectively. In case of male and female stages, it has been recorded as 95.47% and 95.50%, respectively. Thus, a significant difference was not found between female and male mortality rates. Prey consumption of 1st, 2nd, 3rd, 4th and 5th surviving instars was noted as 8.01, 11. 72, 13.24, 16.93 and 20.49 number of eggs/day while in females and males, it was 12.05 and 12.71 number of eggs/day, respectively. Hatching ratio of treated eggs of predator was 25.32±4.08. As far as the behavioral test is concerned, it has been indicated that Diflubenzuron has 65% repellent effect on the newly emerged male and female stages of the predatory bug while using Y-tube olfactometer under laboratory conditions.

Keywords: behavior, biological stages, diflubenzuron, effectiveness, pesticide, predatory bug

Procedia PDF Downloads 512

Authors: Nicole Banton

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The maternal and infant mortality rate of Blacks is three times that of Whites in the US. Research indicates that breastfeeding lowers both. In this paper, the researcher examines how the ideas that Black/African American mothers had about breastfeeding before, during, and after pregnancy (postpartum) affected whether or not they initiated breastfeeding. The researcher used snowball sampling to recruit thirty African-American mothers from the Orlando area. At the time of her interview, each mother had at least one child who was at least three years old. Through in-depth face-to-face interviews, the researcher investigated how mothers’ healthcare providers affected their decision-making about infant feeding, as well as how the type of birth that she had (e.g., preterm, vaginal, c-section, full term) affected her actual versus idealized infant feeding practice. Through our discussions, we explored how pre-pregnancy perceptions, birth and postpartum experiences, social support, and the discourses surrounding motherhood within an African-American context affected the perceptions and experiences that the mothers in the study had with their infant feeding practice(s). Findings suggest that the pregnancy and birth experiences of the mothers in the study influenced whether or not they breastfed exclusively, combined breastfeeding and infant formula use, or used infant formula exclusively. Specifically, the interplay of invocation of agency (the ability to control their bodies before, during, and after birth), birth outcomes, and the interaction that the mothers in this study had with resources, human and material, had the highest impact on the initiation, duration, and attitude toward breastfeeding.

Keywords: African American mothers, maternal health, breastfeeding, birth, midwives, obstetricians, hospital birth, breast pumps, formula use, infant feeding, lactation consultant, postpartum, vaginal birth, c-section, familial support, social support, work, pregnancy

Procedia PDF Downloads 66

Authors: Prakash Chandra Subedi

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Family farming is the family based farming activities, where the farmers cultivate their farm themselves and all the members of the family are engaged in farming as per their skill, age, and physical strength. This study was conducted to examine the food sufficiency level of family farmers and, was carried in the four VDCs of Kavrepalanchowk district -Jaisithok Mandan, Mahadevsthan Mandan and Gairi Bisouna Deupur. A total of 115 households determined as the sample size from each of the four VDCs were randomly visited for interview in the study. The size of land holding was found to be very small and fragmented. The quality of soil was fertile and could yield high production if irrigation existed. The labour used patterns were significant number of family labour but due to high youth migration there were labour shortage. The rate of adoption of agri-technology was low but the households adopting insectides/pesticides and chemical fertilizers were found to be high without any knowledge regarding its using techniques. In conclusion, the study highpoint that the crop production and food sufficiency level of the family farmers of the Kavrepalanchowk district is decreasing. Many farmers were leaving their farming and started seeking opportunity to go for foreign employment or engaged in non-agricultural activities in urban areas. If no action is taken timely, there may come situation that we will have to depend on imports for all the food requirements. Thus, the study reveals that the family farming could act as an agent for ensuring food sufficiency for all, if proper policies is promoted to family farmers with legal titles to their land or promoted with sustainable agriculture methods or provided with proper agri-technology or given their share of respect and responsibilities that farming as honorable profession.

Keywords: family farming, technology transfer, crop production, food sufficiency

Procedia PDF Downloads 324

Authors: Khaled Al-Badani, James Ren, Lisa Li, David Allanson

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Droplet formation is an important process in many engineering systems and manufacturing procedures, which includes welding, biotechnologies, 3D printing, biochemical, biomedical fields and many more. The volume and the characteristics of droplet formation are generally depended on various material properties, microfluidics and fluid mechanics considerations. Hence, a detailed investigation of this process, with the aid of numerical computational tools, are essential for future design optimization and process controls of many engineering systems. This will also improve the understanding of changes in the properties and the structures of materials, during the formation of the droplet, which is important for new material developments to achieve different functions, pending the requirements of the application. For example, the shape of the formed droplet is critical for the function of some final products, such as the welding nugget during Capacitor Discharge Welding process, or PLA 3D printing, etc. Although, most academic journals on droplet formation, focused on issued with material transfer rate, surface tension and residual stresses, the general emphasis on the characteristics of droplet shape has been overlooked. The proposed work for this project will examine theoretical methodologies, experimental techniques, and numerical modelling, using ANSYS FLUENT, to critically analyse and highlight optimization methods regarding the formation of pendant droplet. The project will also compare results from published data with experimental and numerical work, concerning the effects of key material parameters on the droplet shape. These effects include changes in heating/cooling rates, solidification/melting progression and separation/break-up times. From these tests, a set of objectives is prepared, with an intention of improving quality, stability and productivity in modelling metal welding and 3D printing.

Keywords: computer modelling, droplet formation, material distortion, materials forming, welding

Procedia PDF Downloads 273

Authors: Zainab Bibi, Afsheen Aman, Shah Ali Ul Qader

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Endo-β-1,4-xylanases [EC 3.2.1.8] are one of the major groups of enzymes that are involved in degradation process of xylan and have several applications in food, textile and paper processing industries. Due to broad utility of endo-β-1,4-xylanase, researchers are focusing to increase the productivity of this hydrolase from various microbial species. Harsh industrial condition, faster reaction rate and efficient hydrolysis of xylan with low risk of contamination are critical requirements of industry that can be fulfilled by synthesizing the enzyme with efficient properties. In the current study, a newly isolated thermophile Geobacillus stearothermophilus KIBGE-IB29 was used in order to attain the maximum production of endo-1,4-β-xylanase. Bacterial culture was isolated from soil, collected around the blast furnace site of a steel processing mill, Karachi. Optimization of various nutritional and physical factors resulted the maximum synthesis of endo-1,4-β-xylanase from a thermophile. High production yield was achieved at 60°C and pH-6.0 after 24 hours of incubation period. Various nitrogen sources viz. peptone, yeast extract and meat extract improved the enzyme synthesis with 0.5%, 0.2% and 0.1% optimum concentrations. Dipotassium hydrogen phosphate (0.25%), potassium dihydrogen phosphate (0.05%), ammonium sulfate (0.05%) and calcium chloride (0.01%) were noticed as valuable salts to improve the production of enzyme. The thermophilic nature of isolate, with its broad pH stability profile and reduced fermentation time indicates its importance for effective xylan saccharification and for large scale production of endo-1,4-β-xylanase.

Keywords: geobacillus, optimization, production, xylanase

Procedia PDF Downloads 299

Authors: Yao Song

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Objectives: We aimed to explore the clinicodemographic characteristics and prognosis of grey zone squamous cell cancer (GZSCC) located in the overlapping or ambiguous area of the oral cavity and oropharynx and to identify valuable factors that would improve its differential diagnosis and prognosis. Methods: Information of GZSCC patients in the Surveillance, Epidemiology, and End Results (SEER) database was compared to patients with an oral cavity (OCSCC) and oropharyngeal (OPSCC) squamous cell carcinomas with corresponding HPV status, respectively. Kaplan-Meier method with log-rank test and multivariate Cox regression analysis were applied to assess associations between clinical characteristics and overall survival (OS). A predictive model integrating age, gender, marital status, HPV status, and staging variables was conducted to classify GZSCC patients into three risk groups and verified internally by 10-fold cross validation. Results: A total of 3318 GZSCC, 10792 OPSCC, and 6656 OCSCC patients were identified. HPV-positive GZSCC patients had the best 5-year OS as HPV-positive OPSCC (81% vs. 82%). However, the 5-year OS of HPV-negative/unknown GZSCC (43%/42%) was the worst among all groups, indicating that HPV status and the overlapping nature of tumors were valuable prognostic predictors in GZSCC patients. Compared with the strategy of dividing GZSCC into two groups by HPV status, the predictive model integrating more variables could additionally identify a unique high-risk GZSCC group with the lowest OS rate. Conclusions: GZSCC patients had distinct clinical characteristics and prognoses compared with OPSCC and OCSCC; integrating HPV status and other clinical factors could help distinguish GZSCC and predict their prognosis.

Keywords: GZSCC, OCSCC, OPSCC, HPV

Procedia PDF Downloads 66

Authors: Anoff Anim, Lila A. M. Mahmoud, Maria Katsikogianni, Sanjit Nayak

Abstract:

Sustained and controlled delivery of antimicrobial drugs have been largely studied recently using metal organic frameworks (MOFs)and different polymers. However, much attention has not been given to combining both MOFs and biodegradable polymers, which would be a good strategy in providing a sustained gradual release of the drugs. Herein, we report a comparative study of the sustained and controlled release of widely used antibacterial drugs, cephalexin and metronidazole, from zinc-based MOF-5 incorporated in biodegradable polycaprolactone (PCL) and poly-lactic glycolic acid (PLGA) membranes. Cephalexin and metronidazole were separately incorporated in MOF-5 post-synthetically, followed by their integration into biodegradable PLGA and PCL membranes. The pristine MOF-5 and the loaded MOFs were thoroughly characterized by FT-IR, SEM, TGA and PXRD. Drug release studies were carried out to assess the release rate of the drugs in PBS and distilled water for up to 48 hours using UV-Vis Spectroscopy. Four bacterial strains from both the Gram-positive and Gram-negative types, Staphylococus aureus, Staphylococuss epidermidis, Escherichia coli, Acinetobacter baumanii, were tested against the pristine MOF, pure drugs, loaded MOFs and the drug-loaded MOF-polymer composites. Metronidazole-loaded MOF-5 composite of PLGA (PLGA-Met@MOF-5) was found to show highest efficiency to inhibit the growth of S. epidermidis compared to the other bacteria strains while maintaining a sustained minimum inhibitory concentration (MIC). This study demonstrates that the combination of biodegradable MOF-polymer composites can provide an efficient platform for sustained and controlled release of antimicrobial drugs and can be a potential strategy to integrate them in biomedical devices.

Keywords: antimicrobial resistance, biodegradable polymers, cephalexin, drug release metronidazole, MOF-5, PCL, PLGA

Procedia PDF Downloads 120

Authors: Pradeep Lamichhane

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Plasma-assisted nitrogen fixation is a process by which atomic nitrogen generated by plasma is converted into ammonia (NH₃) or related nitrogenous compounds. Nitrogen fixation is essential to plant because fixed inorganic nitrogen compounds are required to them for the biosynthesis of all nitrogen-containing organic compounds, such as amino acids and proteins, nucleoside triphosphates and nucleic acid. Most of our atmosphere is composed of nitrogen; however, the plant cannot absorb it directly from the air ambient. As a portion of the nitrogen cycle, nitrogen fixation fundamental for agriculture and the manufacture of fertilizer. In this study, plasma-assisted nitrogen fixation was performed by exposing a non-thermal atmospheric pressure nitrogen plasma generated a sinusoidal power supply (with an applied voltage of 10 kV and frequency of 33 kHz) on a water surface. Besides this, UV excitation of water molecules at the water interface was also done in order to disassociate water. Hydrogen and hydroxyl radical obtained from this UV photolysis electrochemically combine with nitrogen atom obtained from plasma. As a result of this, nitrogen fixation on plasma-activated water (PAW) significantly enhanced. The amount of nitrogen-based products like NOₓ and ammonia (NH₃) synthesized by this combined process of UV and plasma are 1.4 and 2.8 times higher than those obtained by plasma alone. In every 48 hours, 20 ml of plasma-activated water (pH≈3.15) for 10 minutes with moderate concentrations of NOₓ, NH₃ and hydrogen peroxide (H₂O₂) was irrigated on each corn plant (Zea Mays). It was found that the PAW has shown a significant impact on seeds germination rate and improved seedling growth. The result obtained from this experiment suggested that crop yield could increase in a short duration. In the future, this experiment could open boundless opportunities in plasma agriculture to mobilize nitrogen because nitrite, nitrate, and ammonia are more suitable for plant uptake.

Keywords: plasma-assisted nitrogen fixation, nitrogen plasma, UV excitation of water, ammonia synthesis

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Authors: Armana Huq

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Railway networks have a significant role in the economy of any country. Similar to other transportation modes, many lives suffer from fatalities or injuries caused by accidents related to the railway. Railway accidents are not as common as roadway accidents yet they are more devastating and damaging than other roadway accidents. Despite that, issues related to railway accidents are not taken into consideration with significant attention as a major threat because of their less frequency compared to other accident categories perhaps. However, the Federal Railroad Administration reported nearly twelve thousand train accidents related to the railroad in the year 2014, resulting in more than eight hundred fatalities and thousands of injuries in the United States alone of which nearly one third fatalities resulted from railway crossing accidents. From an analysis of railway accident data of six years (2005-2010), it has been revealed that 344 numbers of the collision were occurred resulting 200 people dead and 443 people injured in Bangladesh. This paper includes a comprehensive overview of the railway safety situation in Bangladesh from 1998 to 2015. Each year on average, eight fatalities are reported in at-grade level crossings due to railway accidents in Bangladesh. In this paper, the number of railway accidents that occurred in Bangladesh has been presented and a fatality rate of 58.62% has been estimated as the percentage of total at-grade railway level crossing accidents. For this study, analysis of railway accidents in Bangladesh for the period 1998 to 2015 was obtained from the police reported accident database using MAAP (Microcomputer Accident Analysis Package). Investigation of the major contributing factors to the railway accidents has been performed using the Multinomial Logit model. Furthermore, hotspot analysis has been conducted using ArcGIS. Eventually, some suggestions have been provided to mitigate those accidents.

Keywords: safety, human factors, multinomial logit model, railway

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Authors: Nickolay Nosik, Dmitry Nosik, Marina Bochkova, Nina Kondrashina, Olga Lobach

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The bactericidal effect of UV radiation is known for long time and widely used for inactivation of pathogens but for viruses it is not so uniform. Due to a wide variety of viruses their sensitivity to UV radiation is quite different and not quite predictable. The goal of the study was to determine the inactivation kinetics of UV radiation ( 254 nm) of the viruses of social importance (HIV), as well as test-viruses (poliovirus, adenovirus) used for the evaluation of the viral inactivation efficacy of germicides. Methods: DNA viruses- adenovirus, type 5; Herpes simplex virus (HSV), type 1, and RNA viruses–human immunodeficiency virus (HIV), type 1 and poliovirus, type 1 (Sabin strain) were obtained from State collection of viruses ( The D.I. Ivanovsky Institute of Virology). The source of UV radiation was a 15-watt low-pressure mercury vapor lamp (over 60% 254nm). The samples of 5cm2 were placed direct under the UV lamp flow (h-0.3m). Log reduction value was used as a marker for the rate of virus inactivation. Results: The data obtained indicate that poliovirus (one of the viruses most resistant to chemical germicides) and HSV are rather sensitive to UV radiation ( D90 =250-311 J/m2). Adenovirus is much more resistant to UV radiation (750 J/m2 ). The kinetics of adenovirus inactivation : 0 min- 5.0 lg TCID50, 10 min - 5,0, 15 min -4,0, 30 min – 3.5, 60 min – 1,0, 75 min -0,5 lg TCID50, 90 min –virus not detectable. HIV is most resistant to UV radiation among the studied viruses. It takes more than 4 hrs to inactivate the virus on the surface. D90 = 2000 J/m2 Conclusion: The results of the study show that there is no direct dependence between sensitivity to UV light and the size of the virion or presence\absence of the envelope of the virus. Poliovirus and adenovirus are small viruses (20-30nm poliovirus and 70-90nm adenovirus) and both are non-enveloped viruses but adenovirus 3-fold more resistant to UV radiation than poliovirus. It can be expected that viruses with more complicate structure, like Herpes virus (200nm) or HIV (80-100 nm), would be more sensitive to UV light. However, the very high resistance of HIV to UV radiation needs further investigation. The diverse resistance of the different viruses to UV radiation should be taken into the account when UV light is used to inactivate infectious viruses in hospitals and other public environments.

Keywords: HIV, HSV, inhibition of viruses, UV radiation

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Authors: Ameni Mahmoudi, Manel Troudi, Paolo Bondavalli, Nabil Sghaier

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In this study, the charge storage on thin-film SWCNT transistors was investigated, and C-V hysteresis tests showed that interface charge trapping effects predominate the memory window. Two electrode materials were utilized to demonstrate that selecting the appropriate metal electrode clearly improves the conductivity and, consequently, the SWCNT thin-film’s memory effect. Because their work function is similar to that of thin-film carbon nanotubes, Ti contacts produce higher charge confinement and show greater charge storage than Pd contacts. For Pd-contact CNTFETs and CNTFETs with Ti electrodes, a sizable clockwise hysteresis window was seen in the dual sweep circle with a threshold voltage shift of V11.52V and V9.7V, respectively. The SWCNT thin-film based transistor is expected to have significant trapping and detrapping charges because of the large C-V hysteresis. We have found that the predicted stored charge density for CNTFETs with Ti contacts is approximately 4.01×10-2C.m-2, which is nearly twice as high as the charge density of the device with Pd contacts. We have shown that the amount of trapped charges can be changed by sweeping the range or Vgs rate. We also looked into the variation in the flat band voltage (V FB) vs. time in order to determine the carrier retention period in CNTFETs with Ti and Pd electrodes. The outcome shows that memorizing trapped charges is about 300 seconds, which is a crucial finding for memory function mimicking.

Keywords: charge storage, thin-film SWCNT based transistors, C-V hysteresis, memory effect, trapping and detrapping charges, stored charge density, the carrier retention time

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Authors: Hidayah Triana, Mahir S. Gani, Asmi Citra Malina, Hamka

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This study was conducted to determine genetic diversity of tiger groupers that are resistant to V. parahaemolyticus and tolerant to low extreme salinities. This research is useful to obtain superior broodstock of fish. Tiger grouper used were 6 to 8 cm obtained from Brackish Water Aquaculture Research Center Gondol (Bali). This study consists of four stages: preliminary stage was adaptation of fish exposed to several concentrations of V. parahaemolyticus (103, 104, 105, 106, and 107 CFU / ml); second stage was test of Lethal Concentration (LC50) of bacteria to fish; third stage was salinity tolerance test (low salinity 12, 14 and 16 ppt) and fourth stage was analysis of DNA profiles. For DNA profiles analysis, genomic DNA of fish were extracted for PCR using primers YNZ-22 and UBC-122 and visualized by electrophoresis method. The results showed that Lethal concentration of bacteria (LC50) to fish was 1,56x106 CFU/ml. Furthermore, survival rate of groupers exposed with low salinities (12, 14, 16 ppt) survival rates were found to be 54,17 %, 66,67 % and 79,16 % respectively. Average of DNA fragment (5 fragments) generated from primer UBC-122 in the group of fish resistant to V.parahaemolyticus and tolerant to low salinities was similar to group of susceptible to low salinities. Primer YNZ-22 generated more diverse of DNA fragments (8,0 and 5,8 fragments) both in the group of fish tolerant and susceptible to low salinities compared to primer UBC-122 (5,0 fragments). Size of DNA 1.5 kb resulted from primer YNZ-22. Primer YNZ-22 generated 4 (50 %) and 3 (42,8 %) polymorfic fragments in the group of fish tolerant and susceptible to low salinities, respectively. Four (4) monomorfic fragments were found both in the group of fish tolerant and susceptible to low salinities. Primer UBC-122 generated 6 (85,7 %) and 9 (90,0 %) polymorfic fragments in the fish tolerant and susceptible to low salinities, respectively.

Keywords: genetic diversity, epinephelus fuscoguttatus, V. parahaemolyticus, PCR-RAPD, low extreme salinity

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Authors: Diego Cruz, Helbert Arevalo, Diana Vernot

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In 2013, the Food and Agriculture Organization of the United Nations (FAO) said that insect production for food and feed could become an economic opportunity for rural women in developing countries. However, since then, just a few initiatives worldwide had tried to implement this kind of project in zones of tropical countries without previous experience in cricket production and insect human consumption, such as Colombia. In this project, ArthroFood company and the University of La Sabana join efforts to make a holistic multi-perspective analysis from biological, economic, culinary, and social sides of the Gryllodes sigillatus production by rural women of the municipality of La Mesa, Cundinamarca, Colombia. From a biological and economic perspective, G. sigillatus production in a 60m2 greenhouse was evaluated considering the effect of rearing density and substrates on final weight and length, developing time, survival rate, and proximate composition. Additionally, the production cost and labor hours were recorded for five months. On the other hand, from a socio- economic side, the intention of the rural women to implement cricket farms or micro-entrepreneurship around insect production was evaluated after developing ethnographies and empowerment, entrepreneurship, and cricket production workshops. Finally, the results of the elaboration of culinary recipes with cricket powder incorporating cultural aspects of the context of La Mesa, Cundinamarca, will be presented. This project represents Colombia's first attempt to create a social business model of cricket production involving rural women, academies, the private sector, and local authorities.

Keywords: cricket production, developing country, edible insects, entrepreneurship, insect culinary recipes

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Authors: S. M. Javad Davoodi, Mojtaba Shourian

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Groundwater table close to the ground surface causes major problems in construction and mining operation. One of the methods to control groundwater in such cases is using pumping wells. These pumping wells remove excess water from the site project and lower the water table to a desirable value. Although the efficiency of this method is acceptable, it needs high expenses to apply. It means even small improvement in a design of pumping wells can lead to substantial cost savings. In order to minimize the total cost in the method of pumping wells, a simulation-optimization approach is applied. The proposed model integrates MODFLOW as the simulation model with Firefly as the optimization algorithm. In fact, MODFLOW computes the drawdown due to pumping in an aquifer and the Firefly algorithm defines the optimum value of design parameters which are numbers, pumping rates and layout of the designing wells. The developed Firefly-MODFLOW model is applied to minimize the cost of the dewatering project for the ancient mosque of Kerman city in Iran. Repetitive runs of the Firefly-MODFLOW model indicates that drilling two wells with the total rate of pumping 5503 m3/day is the result of the minimization problem. Results show that implementing the proposed solution leads to at least 1.5 m drawdown in the aquifer beneath mosque region. Also, the subsidence due to groundwater depletion is less than 80 mm. Sensitivity analyses indicate that desirable groundwater depletion has an enormous impact on total cost of the project. Besides, in a hypothetical aquifer decreasing the hydraulic conductivity contributes to decrease in total water extraction for dewatering.

Keywords: groundwater dewatering, pumping wells, simulation-optimization, MODFLOW, firefly algorithm

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Authors: Tanveer Hussain, Misbah Hussain, Masroor Ellahi Babar, Muhammad Traiq Pervez, Fiaz Hussain, Sana Zahoor, Rashid Saif

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Interleukin 2 (IL-2) is a cytokine which is produced by activated T cells, play important role in immune response against antigen. It act in both autocrine and paracrine manner. It can stimulate B cells and various other phagocytic cells like monocytes, lymphokine-activated killer cells and natural killer cells. Acting in autocrine fashion, IL-2 protein plays a crucial role in proliferation of T cells. IL-2 triggers the release of pro and anti- inflammatory cytokines by activating several pathways. In present study, exon 1 of IL-2 gene of four local Pakistani breeds (Dera Din Panah, Beetal, Nachi and Kamori) from two provinces was amplified by using reported Ovine IL-2 primers, yielding PCR product of 501 bp. The sequencing of all samples was done to identify the polymorphisms in amplified region of IL-2 gene. Analysis of sequencing data resulted in identification of one novel nucleotide substitution (T→A) in amplified non-coding region of IL-2 gene. Comparison of IL-2 gene sequence of all four breeds with other goat breeds showed high similarity in sequence. While phylogenetic analysis of our local breeds with other mammals showed that IL-2 is a variable gene which has undergone many substitutions. This high substitution rate can be due to the decreased or increased changed selective pressure. These rapid changes can also lead to the change in function of immune system. This pioneering study of Pakistani goat breeds urge for further studies on immune system of each targeted breed for fully understanding the functional role of IL-2 in goat immunity.

Keywords: interleukin 2, mutational analysis, phylogeny, goat breeds, Pakistan

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Authors: Mohammad Talha, Abdullah Sallehhuddin Abdullah Salim, Abdul Aziz Abdul Jalil, Norzarina Md Yatim

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The significant contribution of institutional investors across the globe in socially responsible investment (SRI) is well-documented in the literature. Nevertheless, how the SRI behavior of pressure-resistant, pressure-sensitive and pressure-indeterminate institutional investors remain unexplored extensively. This study examines the moderating effect of institutional investors towards socially responsible investment behavior in the context of emerging economies. This study involved 229 institutional investors in Malaysia. A total of 1,145 questionnaires were distributed. Out of these, 308 (130 pressure sensitive institutional investors and 178 pressure resistant institutional investors), representing a usable rate of 26.9 per cent, were found fit for data analysis. Utilizing multi-group analysis via AMOS, this study found evidence for the presence of moderating effect by a type of institutional investor topology in socially responsible investment behavior. At intentional level, it established that type of institutional investor was a significant moderator in the relationship between subjective norms, and caring ethical climate with intention among pressure-resistant institutional investors, as well as between perceived behavioral controls with intention among pressure-sensitive institutional investors. At the behavioral level, the results evidenced that there was only a significant moderating effect between intention and socially responsible investment behavior among pressure-resistant institutional investors. The outcomes are expected to benefit policy makers, regulators, and market participants in order to leap forward SRI growth in developing economies. Nevertheless, the outcomes are limited to a few factors, and it is believed that future studies shall address those limitations.

Keywords: socially responsible investment, behavior, pressure sensitive investors, pressure insensitive investors, Institutional Investment Malaysia

Procedia PDF Downloads 339

Authors: Katalin Gocze, Gabriella Kiss, Zsuzsanna Gurdan, Krisztian Kvell, Attila Trabert

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Introduction: On a worldwide scale running has become an increasingly popular leisure time activity during the past decade. Since the participation rate of women has risen significantly the aim of our study was to analyze the mental status, sleeping habits and the prevalence of depression among female runners. Methods: Cross-sectional analysis included the use of validated and globally used surveys for the comprehensive evaluation of insomnia (AIS), depression (BDI), exercise dependence (EDS) and exercise addiction (EAI). Recreational and amateur female runners participating at half-marathon events in Hungary were asked to take part in our pilot study. Results: Participants mean age was 42.03±9.03 years. The prevalence of imsomnia was 18.87%. 60.34% has worries regarding their weight and 43.1% think that they have an actual weight problem. 77.6% stated that their body weight has an influence on their mood. 2.7% displayed borderline clinical depression, the prevalence of mild mood disorders was 10.81%. 17.2% had previously problems with disordered eating. Participants had a mean total EDS score of 46.94±15.55 and a mean total of 13.49±3.80 on EAI. Component scores were the highest for tolerance (a need for increased amounts of exercise to achieve the desired effect or a diminished effect occurs with continued use of the same amount of exercise). Conclusion: Even tough running can help improve mental health, tackle depression and overcome adversity, athletes are at risk of experiencing psychological difficulties which have an impact on their physical perfomance as well. Further research can help initiate targeted educational and screening programs to ensure that female athletes find a path to emotional well-being.

Keywords: depression, eating disorder, exercise addiction, exercise dependence, insomnia, running

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Authors: Faizan Asghar, Mohammad Jamal Khattak

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Aging, in general, refers to changes in rheological characteristics of asphalt mixture due to changes in chemical composition over the course of construction and service life of the pavement. The main goal of this study was to investigate the impact of oxidation on fatigue characteristics of a novel HMA composite fabricated with a combination of crumb rubber (CRM) and polyvinyl alcohol (PVA) fiber subject to aging of 7 and 14 days. A flexural beam fatigue test was performed to evaluate several characteristics of control, CRM modified, PVA reinforced, and novel rubber-fiber HMA composite. Experimental results revealed that aging had a significant impact on the fatigue performance of novel HMA composite. It was found that a suitable proportion of CRM and PVA radically affected the performance of novel rubber-fiber HMA in resistance to fracture and fatigue cracking when subjected to long-term aging. The developed novel HMA composite containing 2% CRM and 0.2% PVA presented around 29 times higher resistance to fatigue cracking for a period of 7 days of aging. To develop a cumulative plastic deformation level of 250 micros, such a mixture required over 50 times higher cycles than control HMA. Moreover, the crack propagation rate was reduced by over 90%, with over 12 times higher energy required to propagate a unit crack length in such a mixture compared to conventional HMA. Further, digital imaging correlation analyses revealed a more twisted and convoluted fracture path and higher strain distribution in rubber-fiber HMA composite. The fatigue performance after long-term aging of such novel HMA composite explicitly validates the ability to withstand load repetition that could lead to an extension in the service life of pavement infrastructure and reduce taxpayers’ dollars spent.

Keywords: crumb rubber, PVA fibers, dry process, aging, performance testing, fatigue life

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Authors: Gashaw Abebaw

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Concrete usage in Ethiopia is expanding at a faster rate than before. Cement is the most important and costly ingredient in this respect. The construction industry is currently challenged by cement scarcity and stock market inflation. Scholars' trays, on the other hand, will use natural pozzolan material to substitute cement. Apart from that, Metakaolin has pozzolanic characteristics. According to the industrial mineral occurrence map, Ethiopia kaolin may be found in abundance. Some of them include Debretabor, so it is good to utilize Metakaolin as cement replacement material. In this study, the capability of Ethiopian Metakaolin as a partial substitute for cement in C-25 concrete production with 0%, 5%, 10%, 15%, and 20% replacement of PPC by MA with 0.49 percent water to cement ratio is investigated. The study examines; the chemical properties of MA, Physical properties of cement paste, workability, compressive strength, water absorption, density and sulfate attack of concrete was investigated. The chemical composition of Metakaolin was examined and the summation of SiO₂, AlO₃, and FeO₃ is 86.25% and the ash was classified class N pozzolan. The normal consistency percent of water increases as the MA replacement amount increase and both initial and final setting time rang increase as the MA replacement amount increase. On the 28th day, the compressive strength of concrete with MA replacement of 5%, 10%, and 15% exceeds the goal mean strength (33.5Mpa) with compressive strength enhancements of 2.23 %, 4.05 %, and 2.23 %, respectively. Similarly, on the 56th day, 5 %, 10%, and 15% replacement enhance concrete strength by 2.06 %, 3.06 %, and 1.2 %, respectively. The MA mixed concrete has improved significantly in terms of water absorption and sulphate attack, with a 15% replacement level. MA content Metakaolin could possibly replace cement up to 15%, according to the studies. The study's findings will help to offset cement price increases while also boosting house affordability without significantly degrading.

Keywords: metakaolin, compressive strength, sulphate attack, water absorption, N pozzolan

Procedia PDF Downloads 107