ABSTRACT
The Bachaur is a mediumized draft purpose breed which has been recognized by ICAR-National Bureau of Animal Genetic Resources (NBAGR) Karnal, India, and presently is on the verge of extinction. Since there are no data regarding the seminal parameters of this breed, this work was performed to evaluate seminal parameters of freshly ejaculated semen. A total of three healthy breeding Bachaur bulls aged 2.5-5 years were selected for the study which were maintained under identical managemental conditions. Semen parameters of these bulls were studied across 10 ejaculates. The average scrotal circumference and testicular weight of the three bulls were 27.78 ± 1.2 cm and 400.67 ± 26.6 g, respectively. The average overall volume (mL), pH, concentration (million/mL), liveability (%), abnormality (%), HOST (%) and acrosome integrity (%) were 2.20 ± 0.19, 6.86 ± 0.06, 1245.60 ± 23.49, 85.09 ± 0.91, 4.13 ± 0.06, 81.16 ± 1.18 and 83.54 ± 1.32, respectively. The average overall mass motility of three Bachaur bulls was 3.57 ± 0.06 in 0-5 scale and individual motility averaged 84.78 ± 1.70 per cent. The volume of ejaculates in Bachaur bull seemed to be lower as compared to other exotic and Indian breeds. However, the semen parameters with regard to mass motility, liveability, abnormalities, hypo-osmotic swelling test (HOST) and acrosomal integrity seemed similar to other exotic and Indian breeds.
Subject(s)
Semen Analysis , Semen , Sperm Motility , Animals , Male , Cattle , Semen/physiology , Semen Analysis/veterinary , India , Spermatozoa/physiology , Testis/anatomy & histology , AcrosomeABSTRACT
The voltage-dependent anion channel (VDAC) is a mitochondrial outer membrane protein whose fundamental function is to facilitate and regulate the flow of metabolites between the cytosol and the mitochondrial intermembrane space. Using coarse-grained molecular dynamics simulations, we investigated the dependence of VDAC selectivity towards small inorganic anions on two factors: the ionic strength and the lipid composition. In agreement with experimental data we found that VDAC becomes less anion selective with increasing salt concentration due to the screening of a few basic residues that point into the pore lumen. The molecular dynamics simulations provide insight into the regulation mechanism of VDAC selectivity by the composition in the lipid membrane and suggest that the ion distribution is differently modulated by POPE compared to the POPC bilayer. This occurs through the more persistent interactions of acidic residues located at both rims of the ß-barrel with head groups of POPE which in turn impact the electrostatic potential and thereby the selectivity of the pore. This mechanism occurs not only in POPE single component membranes but also in a mixed POPE/POPC bilayer by an enrichment of POPE over POPC lipids on the surface of VDAC. Thus we show here that computationally-inexpensive coarse-grained simulations are able to capture, in a semi-quantitative way, essential features of VDAC anion selectivity and could pave the way toward a molecular level understanding of metabolite transport in natural membranes.
Subject(s)
Molecular Dynamics Simulation , Phosphatidylcholines/pharmacology , Phosphatidylethanolamines/pharmacology , Voltage-Dependent Anion Channels/metabolism , Animals , Mice , Phosphatidylcholines/chemistry , Phosphatidylethanolamines/chemistry , Salts/chemistry , Salts/pharmacology , Static Electricity , Surface Properties , Voltage-Dependent Anion Channels/chemistryABSTRACT
OBJECTIVES: The single-tablet regimen rilpivirine, emtricitabine and tenofovir alafenamide (RPV/FTC/TAF) for treatment of HIV-1-infected adults was approved based on bioequivalence. We assessed the clinical efficacy, safety and tolerability of switching to RPV/FTC/TAF from either RPV/FTC/tenofovir disoproxil fumarate (TDF) or efavirenz (EFV)/FTC/TDF. METHODS: We conducted two distinct randomized, double-blind, active-controlled, noninferiority trials in participants taking RPV/FTC/TDF (Study 1216) and EFV/FTC/TDF (Study 1160). Each study randomized virologically suppressed (HIV-1 RNA < 50 copies/mL) adults (1:1) to switch to RPV/FTC/TAF or continue their current regimen for 96 weeks. We evaluated efficacy as the proportion with HIV-1 RNA < 50 copies/mL using the Food and Drug Administration snapshot algorithm and prespecified bone and renal endpoints at week 96. RESULTS: We randomized and treated 630 participants in Study 1216 (RPV/FTC/TAF, n = 316; RPV/FTC/TDF, n = 314) and 875 in Study 1160 (RPV/FTC/TAF, n = 438; EFV/FTC/TDF, n = 437). In both studies, the efficacy of switching to RPV/FTC/TAF was noninferior to that of continuing baseline therapy at week 96, with respective percentages of patients with HIV RNA < 50 copies/mL being 89.2% versus 88.5% in Study 1216 [difference 0.7%; 95% confidence interval (CI) -4.3 to +5.8%] and 85.2% versus 85.1% in Study 1160 (difference 0%; 95% CI -4.8 to +4.8%). No participant on RPV/FTC/TAF developed treatment-emergent resistance versus two on EFV/FTC/TDF and one on RPV/FTC/TDF. Compared with continuing baseline therapy, significant improvements in bone mineral density and renal tubular markers were observed in the RPV/FTC/TAF groups (P < 0.001). CONCLUSIONS: Switching to RPV/FTC/TAF from RPV/FTC/TDF or EFV/FTC/TDF was safe and effective and improved bone mineral density and renal biomarkers up to 96 weeks with no cases of treatment-emergent resistance.
Subject(s)
Anti-Retroviral Agents/administration & dosage , Antiretroviral Therapy, Highly Active/methods , Drug Combinations , Drug Substitution/methods , HIV Infections/drug therapy , Adult , Anti-Retroviral Agents/adverse effects , Antiretroviral Therapy, Highly Active/adverse effects , Double-Blind Method , Drug Substitution/adverse effects , Female , HIV-1/isolation & purification , Humans , Male , Middle Aged , RNA, Viral/blood , Treatment Outcome , Viral LoadABSTRACT
BACKGROUND AND PURPOSE: Radiologists should manage the radiation dose for pediatric patients to maintain reasonable diagnostic confidence. We assessed the variation in estimated radiation dose indices for pediatric noncontrast head CT in the United States. MATERIALS AND METHODS: Radiation dose indices for single-phase noncontrast head CT examinations in patients 18 years of age and younger were retrospectively reviewed between July 2011 and June 2016 using the American College of Radiology CT Dose Index Registry. We used the reported volume CT dose index stratified by patient demographics and imaging facility characteristics. RESULTS: The registry included 295,296 single-phase pediatric noncontrast head CT studies from 1571 facilities (56% in male patients and 53% in children older than 10 years of age). The median volume CT dose index was 33 mGy (interquartile range = 22-47 mGy). The volume CT dose index increased as age increased. The volume CT dose index was lower in children's hospitals (median, 26 mGy) versus academic hospitals (median, 32 mGy) and community hospitals (median, 40 mGy). There was a lower volume CT dose index in level I and II trauma centers (median, 27 and 32 mGy, respectively) versus nontrauma centers (median, 40 mGy) and facilities in metropolitan locations (median, 30 mGy) versus those in suburban and rural locations (median, 41 mGy). CONCLUSIONS: Considerable variation in the radiation dose index for pediatric head CT exists. Median dose indices and practice variations at pediatric facilities were both lower compared with other practice settings. Decreasing dose variability through proper management of CT parameters in pediatric populations using benchmarks generated by data from registries can potentially decrease population exposure to ionizing radiation.
Subject(s)
Cone-Beam Computed Tomography/standards , Head/diagnostic imaging , Radiation Dosage , Adolescent , Child , Female , Humans , Infant , Male , Registries , Retrospective Studies , United StatesABSTRACT
OBJECTIVES: Dalbavancin is a long-acting lipoglycopeptide with activity against gram-positives, including methicillin-resistant Staphylococcus aureus (MRSA). The potential for lipoglycopeptides, with half-lives greater than 1 week, to select for resistance is unknown. Here we explore a case of MRSA central line-associated bloodstream infection in which dalbavancin and vancomycin non-susceptibility emerged in a urine isolate collected after the patient was treated with vancomycin and dalbavancin sequentially. METHODS: Isolates from blood and urine underwent susceptibility testing, and whole genome sequencing (WGS). The blood isolate was subjected to successive passage in vitro in the presence of escalating dalbavancin concentrations and the emergent isolate was subjected to repeat susceptibility testing and WGS. RESULTS: The blood isolate was fully susceptible to vancomycin; however, MICs of the urine isolate to dalbavancin, vancomycin, telavancin, and daptomycin were at least fourfold higher than the blood-derived strain. Both strains were indistinguishable by spa and variable number tandem repeat (VNTR) typing, and WGS revealed only seven variants, indicating clonality. Four variants affected genes, including a 3bp in-frame deletion in yvqF, a gene which has been implicated in glycopeptide resistance. Vancomycin and dalbavancin non-susceptibility emerged in the blood isolate after successive passage in vitro in the presence of dalbavancin, and WGS identified a single non-synonymous variant in yvqF. CONCLUSIONS: This is the first case in which VISA has emerged in the context of a dalbavancin-containing regimen. The selection for cross-resistance to vancomycin in vitro by dalbavancin exposure alone is troubling. Clinicians should be aware of the possibility for emergence of dalbavancin non-susceptibility and glycopeptide cross-resistance arising following therapy.
Subject(s)
Anti-Bacterial Agents/administration & dosage , Catheter-Related Infections/drug therapy , Drug Resistance, Multiple, Bacterial , Methicillin-Resistant Staphylococcus aureus/drug effects , Sepsis/drug therapy , Staphylococcal Infections/drug therapy , Teicoplanin/analogs & derivatives , Vancomycin/administration & dosage , Adult , Anti-Bacterial Agents/pharmacology , Blood/microbiology , Catheter-Related Infections/microbiology , DNA Mutational Analysis , Humans , Male , Methicillin-Resistant Staphylococcus aureus/isolation & purification , Microbial Sensitivity Tests , Sepsis/microbiology , Serial Passage , Staphylococcal Infections/microbiology , Teicoplanin/administration & dosage , Teicoplanin/pharmacology , Urine/microbiology , Vancomycin/pharmacology , Whole Genome SequencingABSTRACT
Invariant natural killer T (iNKT) cells are innate-like T cells that respond to lipid antigens presented by CD1d. These immunoregulatory cells have the capacity for rapid cytokine release after antigen recognition and are essential for the activation of multiple arms of the immune response. HIV-1 infection is associated with iNKT cell depletion in the peripheral blood; however, their role in the gastrointestinal-associated lymphoid tissue (GALT) is less well studied. Our results show that iNKT cells are found at a higher frequency in GALT compared with blood, particularly in HIV-1 elite controllers. The capacity of iNKT cells to produce interleukin-4 (IL-4) and IL-10 in the GALT was associated with less immune activation and lower markers of microbial translocation, whereas regulatory T cell frequency showed positive associations with immune activation. We hypothesized that the composition of the microbiota would influence iNKT cell frequency and function. We found positive associations between the abundance of several Bacteroides species and iNKT cell frequency and their capacity to produce IL-4 in the GALT but not in the blood. Overall, our results are consistent with the hypothesis that GALT iNKT cells, influenced by certain bacterial species, may have a key role in regulating immune activation in HIV-1 infection.
Subject(s)
Bacteroides/immunology , Gastrointestinal Microbiome/immunology , HIV Infections/immunology , HIV-1/immunology , Intestines/immunology , Natural Killer T-Cells/immunology , T-Lymphocytes, Regulatory/immunology , Adult , Aged , Antigens, CD1d/metabolism , Cells, Cultured , Female , Humans , Immunity, Innate , Interleukin-10/metabolism , Interleukin-4/metabolism , Lipids/immunology , Male , Middle Aged , Natural Killer T-Cells/microbiology , Natural Killer T-Cells/virology , Young AdultABSTRACT
Chronic HIV infection is characterized by increased immune activation and immunosenescence. p16(INK4a) (p16) is a member of the cyclin-dependent kinase antagonist family that inhibits cellular proliferation, and its protein expression increases during normal chronological aging. However, some infectious diseases can increase the expression of this anti-proliferative protein, potentially accelerating immunological aging and dysfunction. In order to investigate the immunological aging in HIV patients, p16 protein expression was evaluated by flow cytometry, in T cell subsets in a cohort of chronically HIV-infected patients on and off ART as well as age-matched healthy controls. Results showed that untreated HIV-infected subjects exhibited increased per-cell p16 protein expression that was discordant with chronological aging. ART restored p16 protein expression to levels comparable with HIV-negative subjects in the CD4 compartment, but not in CD8 T cells, which can be an indicative of an irreversible activation/exhaustion status on these cells. Additionally, the frequency of activated CD4+ and CD8+ T cells was positively correlated with p16 expression in CD4+ and CD8+ T cells in untreated subjects. In contrast to healthy controls, untreated HIV-infected individuals had increased p16 levels within the effector memory (T-EM) subset, indicating a possible role for this marker in impaired clonal expansion during antiviral effector function. Taken together, these data demonstrate that chronic HIV infection is associated with elevated expression of the cellular aging marker p16 in T cells. ART restored normal p16 levels in the CD4+ T cell compartment, indicating that use of therapy can be of fundamental importance to normal cell cycling and maintaining immune homeostasis
Subject(s)
Allergy and Immunology , VirologyABSTRACT
Herein, chlorophyll and betalain dyes are extracted from fresh spinach leaves and beetroots. Fourier transform infrared spectra are used to identify the characteristic peaks of the extracted dyes. UV-vis light absorption characteristics of the dyes and their mixed counterpart are investigated by varying their pH and temperature. These dyes are used as photo sensitizer for fabrication of zinc oxide photo-anode based dye sensitized solar cells (DSSCs). The photo-voltaic characteristics of the developed DSSCs are measured under simulated solar light (power of incident light 100 mW cm(-2) from Air Mass 1.5G). The solar to electric conversion efficiencies for the chlorophyll, betalain and mixed dye based solar cells are estimated as 0.148%, 0.197% and 0.294% respectively. The highest conversion efficiency for mixed dye based solar cell is attributed due to the absorption of wider range of solar spectrum.
Subject(s)
Beta vulgaris/chemistry , Betalains/chemistry , Chlorophyll/chemistry , Electric Power Supplies , Photosensitizing Agents/chemistry , Spinacia oleracea/chemistry , Betalains/isolation & purification , Chlorophyll/isolation & purification , Coloring Agents/chemistry , Coloring Agents/isolation & purification , Electricity , Electrodes , Light , Photosensitizing Agents/isolation & purification , Plant Leaves/chemistry , Plant Roots/chemistry , Solar Energy , Spectrophotometry, Ultraviolet , Zinc Oxide/chemistryABSTRACT
Factor VIII (FVIII) mutations cause haemophilia A (HA), an X-linked recessive coagulation disorder. Over 1000 missense mutations in FVIII are known and they lead to variable clinical phenotypes (severe, moderate and mild). The exact molecular basis of this phenotypic heterogeneity by FVIII missense mutations is elusive to date. In this study, we aimed to identify the severity determinants that cause phenotypic heterogeneity of HA. We compiled and curated a data set of 766 missense mutations from the repertoire of missense mutations in FVIII. We analysed these mutations by computational programs (e.g. Swiss-PdbViewer) and different mutation analysis servers (e.g. SIFT, PROVEAN, CUPSAT, PolyPhen2, MutPred); and various sequence- and structure-based parameters were assessed for any significant distribution bias among different HA phenotypes. Our analyses suggest that 'mutations in evolutionary conserved residues', 'mutations in buried residues', mutation-induced 'steric clash' and 'surface electrostatic potential alteration' act as risk factors towards severe HA. We have developed a grading system for FVIII mutations combining the severity determinants, and the grading pattern correlates with HA phenotype. This study will help to correctly associate the HA phenotype with a mutation and aid early characterization of novel variants.
Subject(s)
Computer Simulation , Factor VIII/genetics , Hemophilia A/genetics , Hemophilia A/pathology , Mutation, Missense/genetics , Amino Acid Substitution , Conserved Sequence , Factor VIII/chemistry , Genetic Predisposition to Disease , Humans , Hydrogen Bonding , Protein Stability , Protein Structure, Tertiary , Software , Solvents , Static ElectricityABSTRACT
BACKGROUND: The overexpression of oestrogen-related receptor-ß (ERRß) in breast cancer patients is correlated with improved prognosis and longer relapse-free survival, and the level of ERRß mRNA is inversely correlated with the S-phase fraction of cells from breast cancer patients. METHODS: Chromatin immunoprecipitation (ChIP) cloning of ERRß transcriptional targets and gel supershift assays identified breast cancer amplified sequence 2 (BCAS2) and Follistatin (FST) as two important downstream genes that help to regulate tumourigenesis. Confocal microscopy, co-immunoprecipitation (CoIP), western blotting and quantitative real-time PCR confirmed the involvement of ERRß in oestrogen signalling. RESULTS: Overexpressed ERRß induced FST-mediated apoptosis in breast cancer cells, and E-cadherin expression was also enhanced through upregulation of FST. However, this anti-proliferative signalling function was challenged by ERRß-mediated BCAS2 upregulation, which inhibited FST transcription through the downregulation of ß-catenin/TCF4 recruitment to the FST promoter. Interestingly, ERRß-mediated upregulation of BCAS2 downregulated the major G1-S transition marker cyclin D1, despite the predictable oncogenic properties of BCAS2. INTERPRETATION: Our study provides the first evidence that ERRß, which is a coregulator of ERα also acts as a potential tumour-suppressor molecule in breast cancer. Our current report also provides novel insights into the entire cascade of ERRß signalling events, which may lead to BCAS2-mediated blockage of the G1/S transition and inhibition of the epithelial to mesenchymal transition through FST-mediated regulation of E-cadherin. Importantly, matrix metalloprotease 7, which is a classical mediator of metastasis and E-cadherin cleavage, was also restricted as a result of ERRß-mediated FST overexpression.
Subject(s)
Breast Neoplasms/genetics , Follistatin/biosynthesis , Neoplasm Proteins/biosynthesis , Receptors, Estrogen/genetics , Breast Neoplasms/pathology , Cell Line, Tumor , Cell Proliferation , Epithelial-Mesenchymal Transition/genetics , Estrogen Receptor alpha/genetics , Female , Gene Expression Regulation, Neoplastic , Humans , Promoter Regions, Genetic , Receptors, Estrogen/biosynthesis , Signal Transduction , Transcriptional Activation , beta Catenin/geneticsABSTRACT
Alternatives to conventional rigid fusion have been proposed for several conditions related to degenerative disc disease when nonoperative treatment has failed. Semirigid fixation, in the form of dynamic stabilization or PEEK rods, is expected to provide compression under loading as well as an intermediate level of stabilization. This study systematically examines both the load-sharing characteristics and kinematics of these two devices compared to the standard of internal rigid fixators. Load-sharing was studied by using digital pressure films inserted between an artificially machined disc and two loading fixtures. Rigid rods, PEEK rods, and the dynamic stabilization system were inserted posteriorly for stabilization. The kinematics were quantified on ten, human, cadaver lumbosacral spines (L3-S1) which were tested under a pure bending moment, in flexion-extension, lateral bending, and axial rotation. The magnitude of load transmission through the anterior column was significantly greater with the dynamic device compared to PEEK rods and rigid rods. The contact pressures were distributed more uniformly, throughout the disc with the dynamic stabilization devices, and had smaller maximum point-loading (pressures) on any particular point within the disc. Kinematically, the motion was reduced by both semirigid devices similarly in all directions, with slight rigidity imparted by a lateral interbody device.
ABSTRACT
AIM: The purpose of this study was to develop a linear regression model to predict treadmill VO2max scores using non-exercise data. METHODS: In this cross sectional study, one hundred twenty college-aged participants (60 male, 60 female, mean age 22.02±2.29 years) voluntarily participated and successfully completed a maximal graded exercise test (GXT) on a motorized treadmill to assess VO2max (mean±SD; 2.05 L·min-¹±1.03 L·min-¹). The maximal treadmill GXT required participants to exercise to volitional fatigue. RESULTS: Relevant non-exercise data included a mean (±SD) perceived functional ability (PFA) score, and physical activity rating (PA-R) score, body surface area (BSA) of 14.6±3.9, 2.97±1..75, 1.66±0.17, respectively. Multiple linear regression generated the following regression equation (R=0.899, R2=0.805, adjusted R2=0.799, SEE=0.426 L·min-¹): VO2max (L/min)=-1.541+1.096 (gender, 1=male, 0=female) +.081 (PFA) +1.084(BSA). Each predictor variable was statistically significant (P<0.05) with beta weights for gender, PFA, BSA, PA-R, and equal to (-0.518), (0.255), (0.228), (0.092), percent body fat (-0.003), respectively. The accuracy of the model was evaluated by conducting a cross-validation analysis (N.=18). CONCLUSION: This study provides a N-EX regression prediction model that yields results and also provide a convenient and efficient tool that estimate VO2max in healthy college-aged participants in India.
Subject(s)
Oxygen Consumption/physiology , Cross-Sectional Studies , Exercise Test , Female , Humans , India , Linear Models , Male , Models, Biological , Models, Statistical , Predictive Value of Tests , Reproducibility of Results , Surveys and Questionnaires , Young AdultABSTRACT
A systematic study of the gamma radiation levels (indoor and outdoor) in the villages surrounding the uranium-enriched regions around Jaduguda, India has been undertaken by monitoring selected dwellings in six villages. Each dwelling unit was monitored for a total duration of 1 y. The gamma radiation measurements were carried out using card-based CaSO(4): Dy thermoluminescent dosemeters. The estimated average annual gamma dose values for indoor and outdoor were 980 and 924 (µGy y(-1)), respectively, for the entire region studied. The maximum indoor and outdoor gamma doses experienced in North Dungridih and South Dungridih villages were 1305 and 1223 (µGy y(-1)), respectively. The minimum indoor and outdoor gamma dose values observed in Chatikocha village were 624 and 696 (µGy y(-1)), respectively. Seasonal variation of the indoor gamma values was not observed during the year; however, a small variation was seen with the type of building materials used for construction purposes. A statistical analysis was attempted to characterise the distribution of terrestrial gamma radiation obtained in the study area. The average quarterly indoor gamma values for spring, summer, monsoon and winter seasons as prevalent in the regions were 267±71, 262±54, 213±91, 238±66 (µGy 90 d(-1)), respectively. The annual effective doses to the local population residing in the selected dwelling units were estimated to be 0.6 and 0.1 (mSv y(-1)) for indoor and outdoor, respectively, using an occupancy factor of 0.8 and 0.2.
Subject(s)
Air Pollution, Indoor/analysis , Air Pollution, Radioactive/analysis , Calcium Sulfate/chemistry , Construction Materials , Radiation Monitoring , Thermoluminescent Dosimetry/instrumentation , Environmental Exposure , Gamma Rays , Housing , India , Radiation Dosage , Radiation Protection , Risk Assessment , Risk Factors , SeasonsABSTRACT
The concentrations of natural radionuclides in surface soil samples around selected villages of Jaduguda were investigated and compared with the radioactivity level in the region. Concentrations of (238)U, (232)Th, and (40)K were determined by a gamma ray spectrometer using the HPGe detector with 50% relative efficiency, and the radiation dose to the local population was estimated. The average estimated activity concentrations of (238)U, (232)Th, and (40)K in the surface soil were 53.8, 44.2 and 464.2 Bq kg(-1) respectively. The average absorbed dose rate in the study area was estimated to be 72.5 nGy h-1, where as the annual effective dose to the population was 0.09 mSv y-1. A correlation analysis was made between measured dose rate and individual radionuclides, in order to delineate the contribution of the respective nuclides towards dose rate. The radio-elemental concentrations of uranium, thorium and potassium estimated for the soils, in the study area, indicated the enrichment of uranium series nuclide. The results of the present study were subsequently compared with international and national recommended values.
ABSTRACT
Inhalation of radon ((222)Rn) and thoron ((220)Rn) are a major source of natural radiation exposure. Indoor radon-thoron study has been carried out in some dwellings of Ganjam district, southern coastal Orissa, India using LR-115 type II plastic track detectors. Seasonal variation of indoor radon and thoron shows high values in winter and low values in both summer and rainy. The inhalation dose lies in the range of 0-0.06muSvh(-1) and is not high from those found elsewhere in India.
Subject(s)
Air Pollution, Indoor/analysis , Radon/analysis , Air Pollutants, Radioactive , Background Radiation , Housing , India , Radiation Monitoring , SeasonsABSTRACT
Some radon related parameters have been determined through two different techniques (passive and active) in soil and phosphogypsum samples. Emanation factors determined through these techniques show a good agreement for soil samples while for phosphogympsum samples appear large discrepancies. In this paper, these discrepancies are analyzed and explained if non-controlled radon leakages in the passive technique are taken into account.
Subject(s)
Radiation Monitoring/methods , Radon/analysis , Calcium Sulfate/analysis , Phosphorus/analysis , Reproducibility of Results , Soil/analysisABSTRACT
A molecular dynamics simulator coupled to a quantum semiempirical Hamiltonian model was applied to multiscale modeling of the catalytic decomposition of hydrocarbons during carbon nanotube (CNT) and carbon nanofiber (CNF) growth. It was found that catalytic decomposition of acetylene is accompanied by a large energy release and its rate weakly depends on temperature in the range from 20 to 700 degrees C. In contrast, the methane decomposition rate substantially decreases as the iron temperature drops. A comparative analysis of acetylene decomposition on a clean surface and on an oxidized Fe(100) surface showed that the presence of oxygen reduces the decomposition rate by an order of magnitude, but has very little influence on the amount of heat released by the reaction. We also found that oxygen absorbed on the surface of catalyst does not easily diffuse into the catalyst or desorb from the surface. This implies that the surface of the catalyst is quickly covered by oxygen during CNT/CNF growth even at low oxygen flow rates.
Subject(s)
Computer Simulation , Hydrocarbons/chemistry , Models, Chemical , Nanotubes, Carbon/chemistry , Quantum Theory , Catalysis , Surface Properties , Time FactorsABSTRACT
Bone loss around the femoral stems during the insertion of a standard prosthesis is a major problem in hip arthroplasty. Moreover, long periods of use of the standard metallic prosthesis often lead to revision surgery because of disuse osteoporosis (stress shielding). The main factor behind this problem is the material-stiffness mismatch of the bone and implant, with the latter consisting of metals such as stainless steel, Co-Cr-Mo alloy, or Ti6Al4V alloy. Our study aimed to decrease the factor of geometric mismatch by designing and making customized hip prostheses from computed tomography scan data and finite element analysis. Therefore, the inner medullar cavity of the femur would match exactly with the prosthesis. Our results showed that the desired stress-strain values were close to the physiological level. We observed that the maximum Von Mises stresses for the bone and implant were 41.8 MPa and 197 MPa, respectively. An optimization analysis of the taper angle of the prosthesis hip ball for fixation with the stem has also been performed, in which the angle was found to be approximately 2 deg. The taper angle plays an important role in load transfer and safe levels of stress-strain using various ball materials.
ABSTRACT
Coal and its by products often contain significant amounts of radionuclides, including uranium which is the ultimate source of the radioactive gas radon. Burning of coal and the subsequent emission to the atmosphere cause the re-distribution of toxic trace elements in the environment. Due to considerable economic and environmental importance and diverse uses, the collected fly ash has become a subject of worldwide interest in recent years. In the present study, radon exhalation rate and the activity concentration of (238)U, (232)Th and (40)K radionuclides in fly ash samples from Durgapur thermal power plant (WB) have been measured by "Sealed Can technique" using LR-115 type II detectors and a low level NaI (Tl) based gamma ray spectrometer, respectively. Radon exhalation rate varied from 360.0 to 470.0 mBq m(-2)h(-1) with an average value of 406.8 mBq m(-2)h(-1). Activity concentrations of (238)U ranged from 84.8 to 126.4 Bq kg(-1) with an average value of 99.3Bqkg(-1), (232)Th ranged from 98.1 to 140.5 Bq kg(-1) with an average value of 112.9 Bq kg(-1) and (40)K ranged from 267.1 to 364.9 Bq kg(-1) with an average value of 308.9 Bq kg(-1). Radium equivalent activity obtained from activity concentrations is found to vary from 256.5 to 352.8 Bq kg(-1) with an average value of 282.5 Bq kg(-1). Absorbed gamma dose rates due to the presence of (238)U, (232)Th and (40)K in fly ash samples vary in the range 115.3-158.5 nGy h(-1) with an average value of 126.4 nGy h(-1). While the external annual effective dose rate varies from 0.14 to 0.19 mSv y(-1) with an average value of 0.15 mSv y(-1), effective dose equivalent estimated from exhalation rate varies from 42.5 to 55.2 microSv y(-1) with an average value of 47.8 microSv y(-1). Values of external hazard index H(ex) for the fly ash samples studied in this work range from 0.69 to 0.96 with a mean value of 0.77.