Search results for: stress formation

Authors: Susan Marie R. De La Cruz, Bernadette F. De La Cruz, Georgia D. Demavibas

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This study determined the top 10 perceived students’ academic needs, personal needs, personal obstacles in achieving their academic goals, are as they need assistance, and their perceived feelings in math, reading and writing. The North Carolina State College, Student Support Services needs assessment survey was used. The respondents were the randomly chosen122Graduate school students. The top 10 academic needs are as follows: need to improve memory, communication skills, study habits, time management skills, career decisions, vocabulary, math skills, test taking skills, reading comprehension, and the need to reduce math anxiety. Top 10 personal needs are as follows: difficulty meeting deadline, difficulty managing money, inadequate computer skills, afraid of failing graduate school, difficulty participating in class/group discussions, absence from school, anxiety during exams, little or no experience with internet, personal counseling needs, and unsure of university academic procedures. Students’ top 10 perceived personal obstacles were as follows: issues surrounding sickness in family, lack of time management, lack of money, feeling tired, fears to speak in class, poor study habits, problems at home, late in class, too shy, and always feeling sick and easily distracted. Students felt need assistance in areas surrounding personal budget, stress management, motivation, anxiety, depressions, leadership development and goals/decision making. It is recommended that enrichment activities be provided to respond to students’ academic and personal needs. Also, Graduate School Guidance Counselor collaborates with other licensed Guidance Counselors in other colleges to have a well-coordinated and effective delivery of services responsive to students’ needs.

Keywords: academic needs, guidance counsellors, guidance service, needs assessment survey, personal needs, student services

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Authors: Natividad Natalia Angeles Manuel

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In the Dominican Republic, American-Dominican veterans face unique challenges due to their dual identities and wartime experiences. This case study examines an 85-year-old veteran with memory impairments and emotional distress linked to military service. A neuropsychological assessment using standardized tools evaluated cognitive domains and functional abilities. Significant deficits in memory, orientation, semantic memory, and executive functions, alongside symptoms of Post-Traumatic Stress Disorder and depression, were identified. A six-month cognitive stimulation program included tailored interventions to enhance memory, attention, and executive skills through weekly sessions and group activities. Medical and physical therapy support aimed to improve overall cognitive, functional, and emotional outcomes. Follow-up evaluations showed improvements in memory retention, attention, task proficiency, and reduced depressive symptoms, highlighting the program's effectiveness in promoting emotional well-being and quality of life. Despite ongoing memory challenges and military-related nightmares, the veteran responded positively to interventions, demonstrating resilience and motivation. This study emphasizes the importance of personalized neuropsychological interventions for American-Dominican veterans in the Dominican Republic. Through assessment tools and focused cognitive stimulation strategies, healthcare providers can successfully alleviate cognitive and emotional challenges stemming from traumatic experiences in elderly veterans. Overall, integrated neuropsychological assessment and stimulation programs are shown to enhance cognitive resilience and emotional well-being, thus contributing to an enhanced quality of life for aging American-Dominican veterans.

Keywords: neuropsychology, cognitive stimulation, American-Dominican veterans, Dominican Republic, PTSD, memory deficits

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Authors: KuiDong Kang, Hye Bin Yim, Su Ah Kim

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Purpose: Tectorigenin is an isoflavone derived from the rhizome of Belamacanda chinensis. In this study, oxygen-induced retinopathy was used to characterize the anti-angiogenic properties of tectorigenin in mice. Methods: ICR neonatal mice were exposed to 75% oxygen from postnatal day P7 until P12 and returned to room air (21% oxygen) for five days (P12 to P17). Mice were subjected to daily intraperitoneal injection of tectorigenin (1 mg/kg, 10 mg/kg) and vehicle from P12 to P17. Retro-orbital injection of FITC-dextran was performed and retinal flat mounts were viewed by fluorescence microscopy. The Central avascular area was quantified from the digital images in a masked fashion using image analysis software (NIH ImageJ). Neovascular tufts were quantified by using SWIFT_NV and neovascular lumens were quantified from a histologic section in a masked fashion. Immunohistochemistry and Western blot analysis were also performed to demonstrate the anti-angiogenic activity of this compound in vivo. Results: In the retina of tectorigenin injected mouse (10mg/kg), the central non-perfusion area was significantly decreased compared to the vehicle injected group (1.76±0.5 mm2 vs 2.85±0.6 mm2, P<0.05). In vehicle-injected group, 33.45 ± 5.51% of the total retinal area was avascular, whereas the retinas of pups treated with high-dose (10 mg/kg) tectorigenin showed avascular retinal areas of 21.25 ±4.34% (P<0.05). High dose of tectorigenin also significantly reduced the number of vascular lumens in the histologic section. Tectorigenin (10 mg/kg) significantly reduced the expression of vascular endothelial growth factor (VEGF), matrix metalloproteinase-2 (MMP-2), MMP-9, and angiotensin II compared to the vehicle injected group. Tectorigenin did not affect CD31 abundance at any tested dose. Conclusions: Our results show that tectorigenin possesses powerful anti-angiogenic properties and can attenuate new vessel formation in the retina after systemic administration. These results imply that this compound can be considered as a candidate substance for therapeutic inhibition of retinal angiogenesis.

Keywords: tectorigenin, anti-angiogenic, retinopathy, Belamacanda chinensis

Procedia PDF Downloads 269

Authors: Tarcisio F. Leao, Bruno Utiyama, Jeison Fonseca, Eduardo Bock, Aron Andrade

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This work presents a blood flow estimator based in Look-Up-Table (LUT) for control of Left Ventricular Assist Device (LVAD). This device has been used as bridge to transplantation or as destination therapy to treat patients with heart failure (HF). Destination Therapy application requires a high performance LVAD; thus, a stable control is important to keep adequate interaction between heart and device. LVAD control provides an adequate cardiac output while sustaining an appropriate flow and pressure blood perfusion, also described as physiologic control. Because thrombus formation and system reliability reduction, sensors are not desirable to measure these variables (flow and pressure blood). To achieve this, control systems have been researched to estimate blood flow. LVAD used in the study is composed by blood centrifugal pump, control, and power supply. This technique used pump and actuator (motor) parameters of LVAD, such as speed and electric current. Estimator relates electromechanical torque (motor or actuator) and hydraulic power (blood pump) via LUT. An in vitro Mock Loop was used to evaluate deviations between blood flow estimated and actual. A solution with glycerin (50%) and water was used to simulate the blood viscosity with hematocrit 45%. Tests were carried out with variation hematocrit: 25%, 45% and 58% of hematocrit, or 40%, 50% and 60% of glycerin in water solution, respectively. Test with bovine blood was carried out (42% hematocrit). Mock Loop is composed: reservoir, tubes, pressure and flow sensors, and fluid (or blood), beyond LVAD. Estimator based in LUT is patented, number BR1020160068363, in Brazil. Mean deviation is 0.23 ± 0.07 L/min for mean flow estimated. Larger mean deviation was 0.5 L/min considering hematocrit variation. This estimator achieved deviation adequate for physiologic control implementation. Future works will evaluate flow estimation performance in control system of LVAD.

Keywords: blood pump, flow estimator, left ventricular assist device, look-up-table

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Authors: Lucja Rodzik, Joanna Lewandowska-Lancucka, Michal Szuwarzynski, Krzysztof Szczubialka, Maria Nowakowska

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The analysis of nucleobases is of great importance for bioscience since their abnormal concentration in body fluids suggests the deficiency and mutation of the immune system, and it is considered to be an important parameter for diagnosis of various diseases. The presented conjugate meets the need for development of the effective, selective and highly sensitive sensor for nucleobase/nucleoside detection. The novel, highly fluorescent cadmium telluride quantum dots (CdTe QDs) functionalized with thymine and stabilized with thioglycolic acid (TGA) conjugates has been developed and thoroughly characterized. Successful formation of the material was confirmed by elemental analysis, and UV–Vis fluorescence and FTIR spectroscopies. The crystalline structure of the obtained product was characterized with X-ray diffraction (XRD) method. The composition of CdTe QDs and their thymine conjugate was also examined using X-ray photoelectron spectroscopy (XPS). The size of the CdTe-thymine was 3-6 nm as demonstrated using atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM) imaging. The plasmon resonance fluorescence band at 540 nm on excitation at 351 nm was observed for these nanoparticles. The intensity of this band increased with the increase in the amount of conjugated thymine with no shift in its position. Based on the fluorescence measurements, it was found that the CdTe-thymine conjugate interacted efficiently and selectively not only with adenine, a nucleobase complementary to thymine, but also with nucleosides and adenine-containing modified nucleosides, i.e., 5′-deoxy-5′-(methylthio)adenosine (MTA) and 2’-O-methyladenosine, the urinary tumor markers which allow monitoring of the disease progression. The applicability of the CdTe-thymine sensor for the real sample analysis was also investigated in simulated urine conditions. High sensitivity and selectivity of CdTe-thymine fluorescence towards adenine, adenosine and modified adenosine suggest that obtained conjugate can be potentially useful for development of the biosensor for complementary nucleobase/nucleoside detection.

Keywords: CdTe quantum dots, conjugate, sensor, thymine

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Authors: Saad M. Howladar, Mostafa M. Rady, Wael M. Semida

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A field experiment was conducted during the two successive seasons of 2012 and 2013 in the Experimental Farm (newly-reclaimed saline soil; EC = 7.8 dS m-1), Faculty of Agriculture, Fayoum University, Fayoum, Egypt to investigate the effect of vitamin C foliar application at the rates of 1, 2, 3 and 4 mM on the possibility of improving growth, seed and oil yields, and some chemical constituents of Helianthus annuus L. plants under the adverse conditions of the selected soil. Significant positive influences of all vitamin C treatments were observed on growth, seed and oil yields and some chemical constituents in both seasons. Compared to unsprayed plants (control), spraying plants with various rates of vitamin C significantly increased vegetative growth traits (i.e. plant height, No. of leaves plant-1, leaf area leaf-1, total leaves area plant-1, and dry weights of leaves and shoot plant-1) and seed and oil yields and their components (i.e. head diameter, seed weight head-1, 100-seed weight, seed yield feddan-1 and oil yield feddan-1). In addition, the concentrations of chlorophyll a, chlorophyll b, total chlorophylls, total carotenoids and total phenols in fresh leaves, and total carbohydrates, total soluble sugars, free proline and some nutrients (i.e. N, P, K, Fe, Mn, and Zn) in dry leaves were also increased significantly with all vitamin C applications. Vitamin C treatment at the rate of 3 mM was generated the best results. These results are important as the potential of vitamin C to alleviate the harmful effects of salt stress offer an opportunity to increase the resistance of sunflower plants to grow under saline conditions of the newly-reclaimed soils.

Keywords: sunflower, Helianthus annuus L., ascorbic acid, salinity, growth, seed yield, oil content, chemical composition

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Authors: J. Bouguebrine, L. Bouabsa

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The ground of study is localized in central Hoggar and contains the most important layers and Stanno-Wolframifére indices of the metallogenic province have tin and wolfram of Hoggar. These layers are always associate with post-orogenetic Panafrican magmatism (GMR) which was set up in the form of circumscribed granitic solid masses of relatively reduced size or in dykes of microgranites. The area studied are in Tounine, Aléméda, Hanana-hananére, Tim Amzi, El Karoussa. The geochemical data processing watch peralumineux character rich person out of Li-F and rare metals (MR). Pegmatites of the type stocksheider, formations of greisens and mineralization Sn-W accompany these granites. Mineralisation Sn-W, expressed particularly well in the seams of quartz and greinsen is spacialement and génitiquement dependent on the maguatism specific to white feldspar-topaz (GMR) (grained and microgrenu). the mineral paragenesis is primarily made up of wolframite and cassetérite. The minerals of gangue are represented by quartz, topaz, the micas containing lithia and the fluorite. A microthermometric study of fluid inclusions related to the granites end on white feldspar-topaz of Hanana, topaz of Hananére, the microgranite of Aléméda, and the seams of quartz D In Tounine (Tiftazouine) and of Tim Amzi; allows to characterize the fluids associated with these layers. It comes out from this study the abundance of aqueous inclusions and three types of fluids were given: -Hot and salted fluids rich in volatile elements particularly CO2; -follow-ups by aquo-carbonic fluids less hot and moderately salted with temperatures of homogenisations (HT) average respectively of 300°C and 180°C; -finally of the aqueous fluids very little salted (≤1%pds.éq.NaCl) and definitely colder. An estimate depths éteé made starting from the diagram of (Haas, 1971) in the system H2O-NaCl, the results are the following: • Inclusion aqueous (L and Lw): correspond to depths of about 50 à500m. • Inclusions aquo-carbonic (Lcw and Lwc): correspond to depths of L order of 600 with 1200m • Carbonic inclusion (Vcw): correspond to depths about 1400à1800m

Keywords: fluid inclusions microthermométrie, cassiterite wolframite, granites with rare metals, Central Hoggar

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Authors: Mirzaii Khadigeh

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Background and objectives: Sexual health education is an important part of health promotion services. The major role of sex education is on mothers’ shoulders. So, they have to be equipped with enough knowledge, attitude and self-efficacy for teens’ education. The present study aimed to determine the effect of team-learning and multimedia software on mothers’ knowledge, attitudes and self-efficacy in sexual health education to 12-14-year-old sons in Mashhad in 1395. Materials and methods: In this research, two experimental and one control group were employed using random sampling, which was done on 132 mothers of high school pupils. They were randomly assigned into experimental and control groups. The data were collected using demographic information and a researcher-constructed questionnaire to investigate the mothers’ knowledge, attitude, and self-efficacy and DASS21(The Depression, Anxiety and Stress Scale). They were run after confirming their reliability and validity. Intervention for the multimedia group was in the form of four CDs- each for 45 minutes- that were given to the mothers each week. At the end of the fourth week, a question-and-answer session was administered for 60 minutes. The team-learning group received intervention once a week (totally four weeks). Two weeks later, the data were collected and analyzed via Chi-square, Fisher, Kruskal-Wallis and ANOVA. Findings: Knowledge, attitude and self-efficacy of mothers in sexual health before the intervention did not have any significant differences (p >0.05). At the end of the study, the difference between the scores of the knowledge, attitude and self-efficacy in the three groups was meaningfully different (p < 0/001), but the difference between the two groups of multimedia and team-learning was not significant (p> 0.05 ). Discussion and conclusion: The result reported the efficacy of both team-leaning and multimedia software, which implies that the multimedia software training method was as effective as team-learning training one on the knowledge, attitude and self-efficacy of mothers. But, the multimedia training method is highly advised due to its availability, flexibility, and interest.

Keywords: training one on the knowledge, attitude, self-efficacy of mothers, boys

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Authors: Odunayo Christy Atewolara-Odule, Olapeju O. Aiyelaagbe

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The search for new natural anti-oxidants has grown tremendously over the years because reactive oxygen species (ROS) production and oxidative stress have been linked to a large number of human degenerative diseases, such as cancer, cardiovascular diseases, inflammation, and diabetes. Tapinanthus bangwensis, a parasitic plant commonly known as mistletoe belonging to the Loranthaceae family, is mostly employed traditionally to treat inflammation, cancer, diabetes, and hypertension to mention a few. In this study, air-dried pulverized leaves and stem of Tapinanthus bangwensis were successively extracted with n-hexane, ethyl acetate, and methanol to give the corresponding crude extracts. The extracts were purified by column chromatography and high-performance liquid chromatography to give the isolated compounds. Structural elucidation was done using mass spectrometry, Fourier transform infra-red, 1D and 2D NMR spectroscopy. The antioxidant activity of the compounds was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ascorbic acid as standard. Three compounds; Friedelin, Eudesmic acid (3,4,5-trimethoxybenzoic) and Methyl-3,4,5-trimethoxybenzoate were isolated from the extracts of Tapinanthus bangwensis. Friedelin was isolated from the ethyl acetate extract of the stem while the two other compounds were isolated from the methanol extract of the leaves. The percentages of free radical scavenging activities of the compounds are as follows: Friedelin, 73.69%, methyl-3,4,5-trimethoxybenzoate, 79.33% and eudesmic, 87.68% anti-oxidant activity which were quite comparable to 93.96% given by ascorbic acid. We are reporting, to our best knowledge, for the first time the occurrence of friedelin and eudesmic acid in Tapinanthus bangwensis. The high anti-oxidant activity of these compounds supports the use of this plant in the management of diabetes and hypertension as they will be useful in combating complications arising from the disease.

Keywords: column chromatography, eudesmic acid, friedelin, Tapinanthus bangwensis

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Authors: Hasan Ziari, Hassan Fazaeli, Seyed Javad Vaziri Kang Olyaei, Asma Sadat Dabiri

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The presence of cracks in concrete pavements is a place for the ingression of corrosive substances, acids, oils, and water into the pavement and reduces its long-term durability and level of service. One of the causes of early cracks in concrete pavements is the plastic shrinkage. This shrinkage occurs due to the formation of negative capillary pressures after the equilibrium of the bleeding and evaporation rates at the pavement surface. These cracks form if the tensile stresses caused by the restrained shrinkage exceed the tensile strength of the concrete. Different climate conditions change the rate of evaporation and thus change the balance time of the bleeding and evaporation, which changes the severity of cracking in concrete. The present study examined the relationship between the balance time of bleeding and evaporation and the area of cracking in the concrete slabs using the standard method ASTM C1579 in 27 different environmental conditions by using continuous video recording and digital image analyzing. The results showed that as the evaporation rate increased and the balance time decreased, the crack severity significantly increased so that by reducing the balance time from the maximum value to its minimum value, the cracking area increased more than four times. It was also observed that the cracking area- balance time curve could be interpreted in three sections. An examination of these three parts showed that the combination of climate conditions has a significant effect on increasing or decreasing these two variables. The criticality of a single factor cannot cause the critical conditions of plastic cracking. By combining two mild environmental factors with a severe climate factor (in terms of surface evaporation rate), a considerable reduction in balance time and a sharp increase in cracking severity can be prevented. The results of this study showed that balance time could be an essential factor in controlling and predicting plastic shrinkage cracking in concrete pavements. It is necessary to control this factor in the case of constructing concrete pavements in different climate conditions.

Keywords: bleeding and cracking severity, concrete pavements, climate conditions, plastic shrinkage

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Authors: Liliana Rytel, Jarosław Całka

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One of the diseases that are very common health problem of modern man is the stomach hyperacidity. It is well known that this pathological state, during which gastric glands secrete too much of hydrochloric acid can be caused due to various factors such as stress, eating habits, alcohol, smoking and some, especially anti-inflammatory drugs. Moreover, hyperacidity is recognized as one of factors leading to development of peptic ulcer disease. Therefore, we analyzed expression of substance P (SP) and neuronal isoform of nitric oxide synthase (nNOS) in the porcine nodose ganglion sensory neurons innervating prepyloric stomach region in physiological state and following intragastric infusion of hydrochloric acid. The study was performed on 8 immature gilts of the Large White Polish breed. All animals were injected retrograde marker Fast Blue (FB) into the anterior prepyloric stomach wall. After injections of FB, pigs were divided into two groups: control (group C; n = 4) and experimental (HCL group, n = 4) and after convalescence period of 23 days, animals of HCL group were subjected to renewed anaesthesia. Then, 0.25 M aqueous solution of hydrochloric acid with a dose of 5 ml/kg body weight was administered intragastrically with use of a stomach tube. On 28th day, all control and HCL pigs were euthanized and bilateral reght (rNG) and left (lNG) were collected. Cryostat sections were processed for double immunofluorescence using anibodies against SP and NOS. Immunofluorescence staining in the even-numbered ganglia nodes showed the presence of FB-positive cells expressing SP (45,9 ± 3,38% in rNG and 60,4 ± 1,71% in lNG), and nNOS (34,9 ± 6,83% in rNG and 49,9 ± 9,32% in lNG). In HCL group increased expression of both SP (54,8 ± 5,34% in rNG and 56,9 ± 3,28 % in lNG) as well as nNOS (54,9 ± 4,45% in rNG and 52,5 ± 2,17 % in lNG) in FB+ perikaria was found. The acquired results suggest that SP and nNOS are neurotransmitters and/ or neuromodulators participating in the sensory regulation of the prepyloric region of porcine stomach function as well as their potential role in development of the stomach inflamatory state.

Keywords: nNOS, nodose ganglion, pig, SP

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Authors: Ganbat Danaa, Chuluundorj Puntsag

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The steel structures of the Oyu-Tolgoi mining Concentrator plant are corroded during operation, which raises doubts about the continued use of some important structures of the plant, which is one of the problems facing the plant's regular operation. As a part of the main operation of the plant, the bottom part of the pressure vessel, which plays an important role in the reliable operation of the concentrate filter-drying unit, was heavily corroded, so it was necessary to study by engineering calculations, modeling, and simulation using modern advanced engineering programs and methods. The purpose of this research is to investigate whether the corroded part of the pressure vessel can be used normally in the future using advanced engineering software and to predetermine the remaining life of the time of the pressure vessel based on engineering calculations. When the thickness of the bottom part of the pressure vessel was thinned by 0.5mm due to corrosion detected by non-destructive testing, finite element analysis using ANSYS WorkBench software was used to determine the mechanical stress, strain and safety factor in the wall and bottom of the pressure vessel operating under 2.2 MPa working pressure, made conclusions on whether it can be used in the future. According to the recommendations, by using sand-blast cleaning and anti-corrosion paint, the normal, continuous and reliable operation of the Concentrator plant can be ensured, such as ordering new pressure vessels and reducing the installation period. By completing this research work, it will be used as a benchmark for assessing the corrosion condition of steel parts of pressure vessels and other metallic and non-metallic structures operating under severe conditions of corrosion, static and dynamic loads, and other deformed steels to make analysis of the structures and make it possible to evaluate and control the integrity and reliable operation of the structures.

Keywords: corrosion, non-destructive testing, finite element analysis, safety factor, structural reliability

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Authors: Yuda Purwana Roswanjaya, Wouter Kohlen, Rene Geurts

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The Trema genus represents a group of fast-growing tropical tree species within the Cannabaceae. Interestingly, five species nested in this lineage -known as Parasponia- can establish rhizobium nitrogen-fixing root nodules, similar to those found in legumes. Parasponia and legumes use a conserved genetic network to control root nodule formation, among which are genes also essential for mycorrhizal symbiosis (the so-called common symbiotic pathway). However, Trema species lost several genes that function exclusively in nodulation, suggesting a loss-of the nodulation trait in Trema. Strikingly, in a Trema orientalis population found in Malaysian Borneo we identified a truncated SYMBIOSIS RECEPTOR KINASE (SYMRK) mutant allele lacking a large portion of the c-terminal kinase domain. In legumes this gene is essential for nodulation and mycorrhization. This raises the question whether Trema orientalis can still be mycorrhized. To answer this question, we established quantitative mycorrhization assay for Parasponia andersonii and Trema orientalis. Plants were grown in closed pots on half strength Hoagland medium containing 20 µM potassium phosphate in sterilized sand and inoculated with 125 spores of Rhizopagus irregularis (Agronutrion-DAOM197198). Mycorrhization efficiency was determined by analyzing the frequency of mycorrhiza (%F), the intensity of the mycorrhizal colonization (%M) and the arbuscule abundance (%A) in the root system. Trema orientalis RG33 can be mycorrhized, though with lower efficiency compared to Parasponia andersonii. From this we conclude that a functional SYMRK kinase domain is not essential for Trema orientalis mycorrhization. In ongoing experiments, we aim to investigate the role of SYMRK in Parasponia andersonii mycorrhization and nodulation. For this two Parasponia andersonii symrk CRISPR-Cas9 mutant alleles were created. One mimicking the TorSYMRKRG33 allele by deletion of exon 13-15, and a full Parasponia andersonii SYMRK knockout.

Keywords: endomycorrhization, Parasponia andersonii, symbiosis receptor kinase (SYMRK), Trema orientalis

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Authors: Sandeep Goyal, Sandeep Saluja

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Natural antioxidants have major role in maintenance of health. Green tea extract principally contains epigallocatechin-3-gallate (EGCG), as its abundant antioxidant constituent. Green tea is consumed daily worldwide as antioxidant to combat CNS diseases and has traditional importance also. EGCG has neuroprotective potential in various animal models of Parkinson disease, Alzheimer’s disease etc. but its exact mechanism has not been ruled out. The present study has been designed to investigate the anti-inflammatory, antioxidant and mitochondrial modulating mechanism of neuroprotective effect of epigallocatechin-3-gallate against rodent model of rotenone induced Parkinson’s disease (PD). The behavioural alterations were assessed by using open field test apparatus, Chatilon’s grip strength test apparatus and elevated plus maze for determining the locomotor activity, grip strength and cognition respectively. Biochemically, various parameters to assess oxidative stress, neuroinflammation and neurochemical estimations were performed on rat brain homogenates. A histological examination of rat brain striatum was done to check the neurodegeneration. Epigallocatechin-3-gallate (EGCG) at 10 & 20 mg/kg, were investigated for their neuroprotective potential along with levodopa as a standard agent. Minocycline, a microglial activation inhibitor, was administered alone and in combination with EGCG. EGCG and minocycline produced ameliorative effect against rotenone induced PD like symptoms by significantly reduced behavioral, biochemical and histological alterations. Results of our study reveal the neuroprotective effect of EGCG and minocycline against rotenone induced PD. Results of our study indicate that EGCG exerted neuroprotective effect against rotenone induced PD via its antioxidant, anti-inflammatory and mitochondrial modulating mechanisms and substantiate its previously reported and traditional claims for its use in CNS diseases.

Keywords: antioxidants, neurotoxicity, rotenone, EGCG

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Authors: Reema Tiwari, U. C. Kulshrestha

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As a key regulator of atmospheric oxidative capacity and secondary aerosol formations, the signatures of reactive nitrogen (Nr) emissions are becoming increasingly evident in the cascade of air pollution, acidification, and eutrophication of the ecosystem. However, their accurate estimates in N budget remains limited by the photochemical conversion processes where occurrence of differential atmospheric residence time of gaseous (NOₓ, HNO₃, NH₃) and particulate (NO₃⁻, NH₄⁺) Nr species becomes imperative to their spatio temporal evolution on a synoptic scale. The present study attempts to quantify such interactions under tropical conditions when low anticyclonic winds become favorable to the advections from west during winters. For this purpose, a diurnal sampling was conducted using low volume sampler assembly where ambient concentrations of Nr trace gases along with their ionic fractions in the aerosol samples were determined with UV-spectrophotometer and ion chromatography respectively. The results showed a spatial gradient of the gaseous precursors with a much pronounced inter site variability (p < 0.05) than their particulate fractions. Such observations were confirmed for their limited photochemical conversions where less than 1 ratios of day and night measurements (D/N) for the different Nr fractions suggested an influence of boundary layer dynamics at the background site. These phase conversion processes were further corroborated with the molar ratios of NOₓ/NOᵧ and NH₃/NHₓ where incomplete titrations of NOₓ and NH₃ emissions were observed irrespective of their diurnal phases along the sampling transect. Their calculations with equilibrium based approaches for an NH₃-HNO₃-NH₄NO₃ system, on the other hand, were characterized by delays in equilibrium attainment where plots of their below deliquescence Kₘ and Kₚ values with 1000/T confirmed the role of lower temperature ranges in NH₄NO₃ aerosol formation. These results would help us in not only resolving the changing atmospheric inputs of reduced (NH₃, NH₄⁺) and oxidized (NOₓ, HNO₃, NO₃⁻) Nr estimates but also in understanding the dependence of Nr mixing ratios on their local meteorological conditions.

Keywords: diurnal ratios, gas-aerosol interactions, spatial gradient, thermodynamic equilibrium

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Authors: Jose Melena, Rosa Santander, Tanya Gonzalez, Richard Duque, Juan Illanes

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Ecuador is one of the countries with the greatest aquatic biodiversity worldwide. In particular, there are at least a dozen native marine species with great aquaculture potential locally. This research concerns one of those species. It has proposed to implement experimental protocols in order to induce spawning and to generate the early larval development of the giant reef clam P. multicostata under controlled conditions. Bioassays were carried out with one adult batch (n= 8) with an average valvar length of 118,4 ± 5,8 mm, which were collected near of the Puerto Santa Rosa (2° 12' 30'' S, 80° 58' 28'' W), Santa Elena Province. During a short acclimation stage, the eight adults of giant reef clam P. multicostata were exposed to thermal stress. Briefly, the experimental protocol for spawning induction was based on the application of 20°C for 1 h and 30°C for 1 h on P. multicostata broodstock at least three consecutive times by one day. After spawning, collected sexual material was released for external fertilization process. After the delivery of gametes, it was achieved 3,25 × 10⁶ viable zygotes. As results, fertilized eggs had 56 µm diameter; while first and second cell divisions were observed to 2,5 h post-fertilization, with individual average length of 68 ± 5 µm and polar body. Latter cell divisions, including gastrula stage, appeared at 9 h post-fertilization, with individual average length of 73 ± 4 µm and trochophore stage at 15 h post-fertilization with individual average length of 75 ± 4 µm. In addition, veliger stage was registered at 20 h post-fertilization with individual average length of 82 ± 6 µm. Umboned larvae appeared at day 8 post-fertilization, with individual average length of 148 ± 6 µm. These pioneering results worldwide can strengthen the local conservation process of the overexploited P. multicostata and to encourage its production for commercial purposes.

Keywords: Ecuador, larval development, Periglypta multicostata, spawning induction

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Authors: Alla Mariseva, Ilze Beitane

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Daily intake of products rich in antioxidants that scavenge free radicals in cell membranes is an effective way to combat oxidative stress. Last year there was noticed higher interest towards the identification and utilization of plants rich in antioxidant compounds as they may behave as preventive medicine. Amaranth seeds due to polyphenols, anthocyanins, flavonoids, and tocopherols are characterized by high antioxidant activity. The study aimed to evaluate the total phenolic content and radical scavenging activity of amaranth seeds cultivated in 2020 in two farms in Latvia. One sample of amaranth seeds came from an organic farm, the other – from a conventional farm. The total phenol content of amaranth seed extracts was measured with the Folin-Ciocalte spectrophotometric method. The total phenols were expressed as gallic acid equivalents (GAE) per 100 g dry weight (DW) of the samples. The antioxidant activity of amaranth seed extracts was calculated based on scavenging activities of the stable 2.2-diphenyl-1-picrylhydrazyl (DPPH˙) radical, the radical scavenging capacity (ABTS) was demonstrated as Trolox mM equivalents (TE) per 100 g-1 dry weight. Three parallel measurements were performed on all samples. There were significant differences between organic and conventional amaranth seeds in terms of total phenolic content and antioxidant activity. Organic amaranth seeds showed higher total phenolic content compared to conventional amaranth seeds, 65.4±6.0 mg GAE 100 g⁻¹ DW and 43.4±7.8 mg GAE 100 g⁻¹ DW respectively. Organic amaranth seeds were also characterized by higher DPPH radical scavenging activity (7.9±0.4 mM TE 100 g⁻¹ of dry matter) and ABTS radical scavenging capacity (13.2±1.5 mM TE 100 g⁻¹ of dry matter). The results obtained on total phenolic content and antioxidant activity of amaranth seeds grown in Latvia confirmed that the samples have a high biological value; therefore, it would be necessary to promote their consumption by including them in various food products, including vegan products, increasing their nutritional value.

Keywords: ABTS, amaranth seeds, antioxidant activity, DPPH, total phenolic content

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Authors: Egoitz Aldanondo, Ekaitz Arruti, Amaia Iturrioz, Ivan Huarte, Fidel Zubiri

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Manufacturing aeronautic structures joining extruded profiles or stringers to sheets or skins of aluminium is a typical manufacturing procedure in aeronautic structures. Although riveting is the conventional manufacturing technology to produce such joints, the Friction Stir Welding (FSW) and Laser Beam Welding (LBW) technologies have also demonstrated their potential for this kind of applications. Therefore, FSW and LBW technologies have the potential to continue their development as manufacturing processes for aeronautic structures showing benefits such as time-saving, light-weighting and overall cost reduction. In addition to that, new aluminium-lithium based alloy developments represent great opportunities for advanced aeronautic structure manufacturing with potential benefits such as lightweight construction or improved corrosion resistance. This work presents the main approaches by FSW and LBW to develop those technologies to produce stiffened panel structures such as fuselage by stringer-skin joints and using innovative aluminium-lithium alloys. Initial welding tests were performed in AA2198-T3S aluminium alloys for LBW technology and with AA2198-T851 for FSW. Later tests for both FSW and LBW have been carried out using AA2099-T83 alloy extrusions as stringers and AA2060-T8E30 as skin materials. The weld quality and properties have been examined by metallographic analysis and mechanical testing, including shear tensile tests and pull-out tests. The analysis of the results have shown the relationships between processing conditions, micro-macrostructural properties and the mechanical strength of the welded joints. The effects produced in the different alloys investigated have been observed and particular weld formation mechanics have been studied for each material and welding technology. Therefore, relationships between welding conditions and the obtained weld properties for each material combination and welding technology will be discussed in this presentation.

Keywords: AA2060-T8E30, AA2099-T83, AA2198-T3S, AA2198-T851, friction stir welding, laser beam welding

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Authors: Sara Khamseh, Kambiz Javanruee, Hamid Khorsand

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Plenty of metallic materials are used for biomedical applications like hip joints and screws. Besides, it is reported that metal platforms such as stainless steel show significant deterioration because of wear and friction. The surface of metal substrates has been coated with a variety of multicomponent coatings to prevail these problems. The carbon-based multicomponent coatings such as metal-added amorphous carbon and diamond coatings are crucially important because of their remarkable tribological performance and chemical stability. In the current study, H-D contained Nb: (a-C) multicomponent coatings (H-D: hexagonal diamond, a-C: amorphous carbon) coated on A 304 steel substrates using an unbalanced magnetron (UBM) sputtering system. The effects of Nb and H-D content and ID/IG ratio on microstructure, mechanical and tribological characteristics of (Nb: H-D: a-C) composite coatings were investigated. The results of Raman spectroscopy represented that a-C phase with a Graphite-like structure (GLC with high value of sp2 carbon bonding) is formed, and its domain size increased with increasing Nb content of the coatings. Moreover, the Nb played a catalyst for the formation of the H-D phase. The nanoindentation hardness value of the coatings ranged between ~17 to ~35 GPa and (Nb: H-D: a-C) composite coatings with more H-D content represented higher hardness and plasticity index. It seems that the existence of extra-hard H-D particles straightly increased hardness. The tribological performance of the coatings was evaluated using the pin-on-disc method under the wet environment of SBF (Simulated Body Fluid). The COF value of the (Nb: H-D: a-C) coatings decreased with an increasing ID/IG ratio. The lower coefficient of friction is a result of the lamelliform array of graphitic domains. Also, the wear rate of the coatings decreased with increasing H-D content of the coatings. Based on the literature, a-C coatings with high hardness and H3/E2 ratio represent lower wear rates and better tribological performance. According to the nanoindentation analysis, hardness and H3/E2 ratio of (Nb: H-D: a-C) multicomponent coatings increased with increasing H-D content, which in turn decreased the wear rate of the coatings. The mechanical and tribological potency of (Nb: H-D: a-C) composite coatings on A 304 steel substrates paved the way for the development of innovative advanced coatings to ameliorate the performance of A 304 steel for biomedical applications.

Keywords: COF, mechanical properties, (Nb: H-D: a-C) coatings, wear rate

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Authors: Panrapee Suttiwan, Rewadee Watakakosol Arunya Tuicomepee, Sakkaphat T. Ngamake

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Alcohol consumption ranks among the top six of health-risk behaviors that lead to disability and death among Thai teenagers. Underage drinkers have higher health risks than their non-drinking peers do. This study, therefore, aimed to explore salient beliefs of Thai teenagers with alcohol reduction and cessation based on the Theory of Planned Behaviour theoretical framework. Participants were 225 high-school and vocational school students, most of whom (60.9%) consumed alcohol almost daily (5-6 times / week), and one-third of whom (33.8%) reported habitual moderate drink. The average age was 16.5 (SD = 0.9), and the average age of the first use of alcohol was 13.7 (SD = 2.2). Instrument was an open-ended questionnaire that elicited beliefs about having alcohol reduction / cessation in the past 12 months. Findings revealed salient benefit beliefs of alcohol reduction / cessation among the teens such as improved physical and mental health, accident and violence avoidance, less sexual risks, money and time saving, better academic performance, and improved relationships. In contrast, the teens identified several disadvantage beliefs such as deteriorating health, social awkwardness, lack of little fun, excitement, and experience, physical uneasiness, stress, and lack of self-confidence. Salient normative groups for alcohol reduction / cessation included parents, elder relatives, siblings, close friends, teachers, boy / girlfriends, and seniors / juniors at school. Situations influencing alcohol reduction / cessation included quarrels with boy / girlfriends, family conflicts, peer pressure, partying and socializing, festive holidays and anniversary celebration, and visiting entertainment places, etc. This study provides empirical evidence that help to identify normative attitudes towards alcohol reduction / cessation and may thus be an important knowledge for public health campaigns seeking to reduce alcohol consumption in this population.

Keywords: alcohol consumption reduction, cessation, salient belief, Thai teenagers

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Authors: Aliro Villacorta, Laura Rubio, Mohamed Alaraby, Montserrat López Mesas, Victor Fuentes-Cebrian, Oscar H. Moriones, Ricard Marcos, Alba Hernández.

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Micro and nano plastics (MNPLs) are emergent environmental pollutants requiring urgent information on their potential risks to human health. One of the problems associated with the evaluation of their undesirable effects is the lack of real samples matching those resulting from the environmental degradation of plastic wastes. To such end, we propose an easy method to obtain polyethylene terephthalate nano plastics from water plastic bottles (PET-NPLs) but, in principle, applicable to any other plastic goods sources. An extensive characterization indicates that the proposed process produces uniform samples of PET-NPLs of around 100 nm, as determined by using a multi-angle and dynamic light scattering methodology. An important point to be highlighted is that to avoid the metal contamination resulting from methods using metal blades/burrs for milling, trituration, or sanding, we propose to use diamond burrs to produce metal-free samples. To visualize the toxicological profile of the produced PET-NPLs, we have evaluated their ability to be internalized by cells, their cytotoxicity, and their ability to induce oxidative stress and induce DNA damage. In this preliminary approach, we have detected their cellular uptake, but without the induction of significant biological effects. Thus, no relevant increases in toxicity, reactive oxygen species (ROS) induction, or DNA damage -as detected with the comet assay- have been observed. The use of real samples, as produced in this study, will generate relevant data in the discussion about the potential health risks associated with MNPLs exposures.

Keywords: nanoplastics, polyethylene terephthalate, physicochemical characterization, cell uptake, cytotoxicity

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Authors: Noe Brice Nkoumbou Kaptchouang, Pierre-Guy Vincent, Yann Monerie

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The present work addresses the modelling and the simulation of crack initiation and propagation in ductile materials which failed by void nucleation, growth, and coalescence. One of the current research frameworks on crack propagation is the use of cohesive-volumetric approach where the crack growth is modelled as a decohesion of two surfaces in a continuum material. In this framework, the material behavior is characterized by two constitutive relations, the volumetric constitutive law relating stress and strain, and a traction-separation law across a two-dimensional surface embedded in the three-dimensional continuum. Several cohesive models have been proposed for the simulation of crack growth in brittle materials. On the other hand, the application of cohesive models in modelling crack growth in ductile material is still a relatively open field. One idea developed in the literature is to identify the traction separation for ductile material based on the behavior of a continuously-deforming unit cell failing by void growth and coalescence. Following this method, the present study proposed a semi-analytical cohesive model for ductile material based on a micromechanical approach. The strain localization band prior to ductile failure is modelled as a cohesive band, and the Gurson-Tvergaard-Needleman plasticity model (GTN) is used to model the behavior of the cohesive band and derived a corresponding traction separation law. The numerical implementation of the model is realized using the non-smooth contact method (NSCD) where cohesive models are introduced as mixed boundary conditions between each volumetric finite element. The present approach is applied to the simulation of crack growth in nuclear ferritic steel. The model provides an alternative way to simulate crack propagation using the numerical efficiency of cohesive model with a traction separation law directly derived from porous continuous model.

Keywords: ductile failure, cohesive model, GTN model, numerical simulation

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Authors: N. A. D. P. Niwunhella, W. G. R. C. K. Sirisena

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Appendicitis is one of the most encountered abdominal emergencies worldwide. Proper clinical diagnosis and appendicectomy with minimal post operative complications are therefore priorities. Aim of this study was to ascertain the overall management of acute appendicitis in Sri Lanka in special preference to delayed primary suturing of the surgical site, comparing other local and international treatment outcomes. Data were collected prospectively from 155 patients who underwent appendicectomy following clinical and radiological diagnosis with ultrasonography. Histological assessment was done for all the specimens. All perforated appendices were managed with delayed primary closure. Patients were followed up for 28 days to assess complications. Mean age of patient presentation was 27 years; mean pre-operative waiting time following admission was 24 hours; average hospital stay was 72 hours; accuracy of clinical diagnosis of appendicitis as confirmed by histology was 87.1%; post operative wound infection rate was 8.3%, and among them 5% had perforated appendices; 4 patients had post operative complications managed without re-opening. There was no fistula formation or mortality reported. Current study was compared with previously published data: a comparison on management of acute appendicitis in Sri Lanka vs. United Kingdom (UK). The diagnosis of current study was equally accurate, but post operative complications were significantly reduced - (current study-9.6%, compared Sri Lankan study-16.4%; compared UK study-14.1%). During the recent years, there has been an exponential rise in the use of Computerised Tomography (CT) imaging in the assessment of patients with acute appendicitis. Even though, the diagnostic accuracy without using CT, and treatment outcome of acute appendicitis in this study match other local studies as well as with data compared to UK. Therefore CT usage has not increased the diagnostic accuracy of acute appendicitis significantly. Especially, delayed primary closure may have reduced post operative wound infection rate for ruptured appendices, therefore suggest this approach for further evaluation as a safer and an effective practice in other hospitals worldwide as well.

Keywords: acute appendicitis, computerised tomography, diagnostic accuracy, delayed primary closure

Procedia PDF Downloads 171

Authors: Roghaye Behroozi

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The development of functionalized metal complexes and nanomaterials has gained significant attention due to their potential in catalyzing selective oxidation and coupling reactions. These catalysts play a crucial role in various industrial and pharmaceutical processes, enhancing the efficiency, selectivity, and sustainability of chemical reactions. This research aims to design and synthesize new functionalized metal complexes and nanomaterials to explore their catalytic applications in the selective oxidation of alcohols and coupling reactions, focusing on improving yield, selectivity, and catalyst reusability. The study involves the synthesis of a nickel Schiff base complex stabilized within 41-MCM as a heterogeneous catalyst. A Schiff base ligand derived from glycine was used to create a tin (IV) metal complex characterized through spectroscopic techniques and computational analysis. Additionally, iron-based magnetic nanoparticles functionalized with melamine were synthesized for catalytic evaluation. Lastly, a palladium (IV) complex was prepared, and its oxidative stability was analyzed. The nickel Schiff base catalyst showed high selectivity in converting primary and secondary alcohols to aldehydes and ketones, with yields ranging from 73% to 90%. The tin (IV) complex demonstrated accurate structural and electronic properties, with consistent results between experimental and computational data. The melamine-functionalized iron nanoparticles exhibited efficient catalytic activity in producing triazoles, with enhanced reaction speed and reusability. The palladium (IV) complex displayed remarkable stability and low reactivity towards C–C bond formation due to its symmetrical structure. The synthesized metal complexes and nanomaterials demonstrated significant potential as efficient, selective, and reusable catalysts for oxidation and coupling reactions. These findings pave the way for developing environmentally friendly and cost-effective catalytic systems for industrial applications.

Keywords: catalysts, Schiff base complexes, metal-organic frameworks, oxidation reactions, nanoparticles, reusability

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Authors: Lina Jassim, Robiah Yunus, , Amran Salleh

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Since nano particles have been assessed as thermo stabilizer, rheology enhancer, and ecology safer, nano drilling fluid can be utilized to overcome the complexity of hole cleaning in highly deviated interval of an extended reach wells. The eccentric annular flow is a flow with special considerations; it forms a vital part of drilling fluid flow analysis in an extended reach wells. In this work eccentric, dual phase flow (different types of rock cuttings with different size were blended with nano fluid) through horizontal well (an extended reach well) are simulated with the help of CFD, Fluent package. In horizontal wells flow occurs in an adverse pressure gradient condition, that makes the particle inside it susceptible to reversed flow. Thus the flow has to be analyzed in a three dimensional manner. Moreover the non-Newtonian behavior of the nano fluid makes the problem really challenging in numerical and physical aspects. The primary objective of the work is to establish a relationship between different flow characteristics with the speed of inner wall rotation. The nano fluid flow characteristics include swirl of flow and its effect on wellbore cleaning ability , wall shear stress and its effect on fluid viscosity to suspend and carry the rock cuttings, axial velocity and its effect on transportation of rock cuttings to the wellbore surface, finally pressure drop and its effect on managed of drilling pressure. The importance of eccentricity of the inner cylinder has to be analyzed as a part of it. Practical horizontal well flows contain a good amount of particles (rock cuttings) with moderate axial velocity, which verified nano drilling fluid ability of carrying and transferring cuttings particles in the highly deviated eccentric annular flow is also of utmost importance.

Keywords: Non-Newtonian, dual phase, eccentric annular, CFD

Procedia PDF Downloads 436

Authors: Cathy SW. Chow, Kristina Shin, Faming Wang, B. C. L. So

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During some dynamic giant puppet performances, an ergonomically designed load carrier system is necessary for the puppeteers to carry a giant puppet body’s heavy load with minimum muscle stress. A load carrier (i.e. prototype) was designed with two small wheels on the foot; and a hybrid spring device on the knee in order to assist the sliding and knee bending movements respectively. Thus, the purpose of this study was to evaluate the effect of three load carriers including two other commercially available load mounting systems, Tepex and SuitX, and the prototype. Ten male participants were recruited for the experiment. Surface electromyography (sEMG) was used to collect the participants’ muscle activities during forward moving and bouncing and with and without load of 11.1 kg that was 60 cm above the shoulder. Five bilateral muscles including the lumbar erector spinae (LES), rectus femoris (RF), bicep femoris (BF), tibialis anterior (TA), and gastrocnemius (GM) were selected for data collection. During forward moving task, the sEMG data showed smallest muscle activities by Tepex harness which exhibited consistently the lowest, compared with the prototype and SuitX which were significantly higher on left LES 68.99% and 64.99%, right LES 26.57% and 82.45%; left RF 87.71% and 47.61%, right RF 143.57% and 24.28%; left BF 80.21% and 22.23%, right BF 96.02% and 21.83%; right TA 6.32% and 4.47%; left GM 5.89% and 12.35% respectively. The result above reflected mobility was highly restricted by tested exoskeleton devices. On the other hand, the sEMG data from bouncing task showed the smallest muscle activities by prototype which exhibited consistently the lowest, compared with the Tepex harness and SuitX which were significantly lower on lLES 6.65% and 104.93, rLES 23.56% and 92.19%; lBF 33.21% and 93.26% and rBF 24.70% and 81.16%; lTA 46.51% and 191.02%; rTA 12.75% and 125.76%; IGM 31.54% and 68.36%; rGM 95.95% and 96.43% respectively.

Keywords: exoskeleton, giant puppet performers, load carriage system, surface electromyography

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Authors: Hany M. Fayed, Rehab F. Abdel-Rahman, Alyaa F. Hessin, Hanan A. Ogaly, Gihan F. Asaad, Abeer A. A. Salama, Sahar Abdelrahman, Mahmoud S. Arbid, Marwan Abd Elbaset Mohamed

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Liver fibrosis is a serious global health problem that occurs as a result of a variety of chronic liver disorders. Apigenin, a flavonoid found in many plants, has several pharmacological properties. The aim of this study was to evaluate the antifibrotic efficacy of apigenin (APG) against experimentally induced hepatic fibrosis in rats via using thioacetamide (TAA) and to explore the possible underlying mechanisms. TAA (100 mg/kg, i.p.) was given three times each week for two weeks to induce liver fibrosis. After TAA injections, APG was given orally (5 and 10 mg/kg) daily for two weeks. Biochemical, molecular, histological and immunohistochemical analyses were performed on blood and liver tissue samples. The functioning of the liver, oxidative stress, inflammation, and liver fibrosis indicators were all evaluated. The findings showed that TAA markedly increased the activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), as well as the levels of malondialdehyde (MDA), focal adhesion kinase (FAK), hypoxia-inducible factor-1 (HIF-1), nuclear factor-κB (NF-κB), transforming growth factor-beta (TGF-β), tumor necrosis factor-alpha (TNF-α) and interleukin-1β (IL-1β) with a reduction in albumin, total protein, A/G ratio, GSH content and interleukin-10 (IL-10). Moreover, TAA elevated the content of collagen I, α -smooth muscle actin (α-SMA), and hydroxyproline in the liver. The treatment with APG in a dose-dependent manner has obviously prevented these alterations and amended the harmful effects induced by TAA. The histopathological and immunohistochemical observations supported this biochemical evidence. The higher dose of APG produced the most significant antifibrotic effect. As a result of these data, APG appears to be a promising antifibrotic drug and could be used as a new herbal medication or dietary supplement in the future for the treatment of liver fibrosis. This effect might be related to the inhibition of the HIF-1/FAK signaling pathway.

Keywords: apigenin, FAK, HIF-1, liver fibrosis, rat, thioacetamide

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Authors: R. Pillai Aparna, S. R. Gandhi

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Soft clay deposits having low strength and high compressibility are found all over the world. Preloading with vertical drains is a widely used method for improving such type of soils. The coefficient of consolidation, irrespective of the drainage type, plays an important role in the design of vertical drains and it controls accurate prediction of the rate of consolidation of soil. Also, the increase in shear strength of soil with consolidation is another important factor considered in preloading or staged construction. To our best knowledge no clear guidelines are available to estimate the increase in shear strength for a particular degree of consolidation (U) at various stages during the construction. Various methods are available for finding out the consolidation coefficient. This study mainly focuses on the variation of, consolidation coefficient which was found out using different methods and shear strength with pressure intensity. The variation of shear strength with the degree of consolidation was also studied. The consolidation test was done using two types of highly compressible clays with vertical, radial and a few with combined drainage. The test was carried out at different pressures intensities and for each pressure intensity, once the target degree of consolidation is achieved, vane shear test was done at different locations in the sample, in order to determine the shear strength. The shear strength of clayey soils under the application of vertical stress with vertical and radial drainage with target U value of 70% and 90% was studied. It was found that there is not much variation in cv or cr value beyond 80kPa pressure intensity. Correlations were developed between shear strength ratio and consolidation pressure based on laboratory testing under controlled condition. It was observed that the shear strength of sample with target U value of 90% is about 1.4 to 2 times than that of 70% consolidated sample. Settlement analysis was done using Asaoka’s and hyperbolic method. The variation of strength with respect to the depth of sample was also studied, using large-scale consolidation test. It was found, based on the present study that the gain in strength is more on the top half of the clay layer, and also the shear strength of the sample ensuring radial drainage is slightly higher than that of the vertical drainage.

Keywords: consolidation coefficient, degree of consolidation, PVDs, shear strength

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Authors: Omowunmi Amao

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Sansevieria liberica belongs to the family Agavaceae (Ruscaceae or Dracaenaceae). They are widely distributed throughout the tropics. Literature review suggests that in Nigeria, the leaves and roots of Sansevieria liberica are used in traditional medicine for the treatment of asthma, abdominal pains, colic, diarrhea, eczema, gonorrhea, hemorrhoids, hypertension, monorrhagia, piles, sexual weakness, snake bites, and wounds of the foot. In this context, the standardized Methanolic extract of roots of Sansevieria liberica is hypothesized for the evaluation of the hypoglycemic activity. Material and Methods: Inbreed adult male sprague-Dawley albino rats were used in the experiment. The suspension of standardized Methanol extract (ME) of Sansevieria liberica was treated for hypoglycemic activity in oral glucose tolerance test (OGTT) method. The suspension of standardized Methanolic extract (ME) of Sansevieria liberica was also treated for hypoglycemic activity in streptozotocin-induced diabetic rats. Results: The Methanolic extract (ME) of Sanseviera liberica root (100 mg/kg, 200mg/kg, and 400 mg/kg) showed potential hypoglycemic activity in diabetic rats, and further in OGTT method. Furthermore, Methanolic extract of Sanseviera liberica root showed significant (P<0.05) increase in final body weight, total hemoglobin, insulin, albumin and high-density lipoprotein levels, however, decrease in fluid intake, glycosylated hemoglobin, urea, creatinine, total cholesterol, triglyceride and low-density lipoprotein levels. Additionally, it improved oxidative stress in terms of reducing lipid peroxidase and superoxide dismutase, and elevating catalase activity. Conclusions: These findings suggest that the Methanolic extract of Sanseviera liberica root was found to be potential hypoglycemic, and would be a promising candidate for the treatment of diabetes.

Keywords: diabetes, Sanseviera liberica, hypoglycemic activity, diabetes and metabolism

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Authors: Nikhil Kumar, Asish Bandyopadhyay

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Laser welding process is a capable technology for forming the automobile, microelectronics, marine and aerospace parts etc. In the present work, a mathematical and statistical approach is adopted to study the laser welding of AISI 304 stainless steel. A robotic control 500 W pulsed Nd:YAG laser source with 1064 nm wavelength has been used for welding purpose. Butt joints are made. The effects of welding parameters, namely; laser power, scanning speed and pulse width on the seam width and depth of penetration has been investigated using the empirical models developed by response surface methodology (RSM). Weld quality is directly correlated with the weld geometry. Twenty sets of experiments have been conducted as per central composite design (CCD) design matrix. The second order mathematical model has been developed for predicting the desired responses. The results of ANOVA indicate that the laser power has the most significant effect on responses. Microstructural analysis as well as hardness of the selected weld specimens has been carried out to understand the metallurgical and mechanical behaviour of the weld. Average micro-hardness of the weld is observed to be higher than the base metal. Higher hardness of the weld is the resultant of grain refinement and δ-ferrite formation in the weld structure. The result suggests that the lower line energy generally produce fine grain structure and improved mechanical properties than the high line energy. The combined effects of input parameters on responses have been analyzed with the help of developed 3-D response surface and contour plots. Finally, multi-objective optimization has been conducted for producing weld joint with complete penetration, minimum seam width and acceptable welding profile. Confirmatory tests have been conducted at optimum parametric conditions to validate the applied optimization technique.

Keywords: ANOVA, laser welding, modeling and optimization, response surface methodology

Procedia PDF Downloads 297