3,841 research outputs found
Morphometric analysis of population samples of soldier caste of Odontotermes obesus (Rambur) (Isoptera, Termitidae, Macrotermitinae)
In order to study morphometric variations in Odontotermes obesus (Rambur), samples from nineteen nests were statistically analyzed for mean, standard deviation, standard error, coefficient of variability and confidence interval (95%) and analysis of variance (Model II ANOVA), The mean values of the different population samples were compared with the student t-test, following the Minitab version and Sokal & Rohlf (1973). In the study of external characters, measurements form a very important component, particularly for identification of species. However, the reliability of the measurements depends on the extent of variability which the structures show within and between colonies. For each individual soldier, the following nine parameters were measured: i) length of head; ii) width of head at mandibles; iii) width of head at the posterolateral ends of antennal carinae; iv) maximum width of head; v) length of left mandible; vi) tooth of left mandible from tip; vii) length of pronotum; viii) width of pronotum; ix) length of postmentum; and x) width of postmentum
Characterization of spark plasma sintered graphene-coated stainless-steel compacts
We investigated the effect of sintering temperature and graphene content on the microstructure, densification, hardness, and wear properties of spark-pl asma sintered (SPS) graphene-coated 316L stainless-steel powders. Four sintering temperatures (850, 900, 950, and 1000 °C) and graphene content of 0.01, 0.1, and 0.5 wt.% were investigated. Re sults showed that sintered density increased with the sintering temperature. Microstructural examination corroborated this result as distinct unsintered powder particles, sinter necks and la rge interparticle pores observed at 850 °C were annihilated at 1000 °C. The 316L stainless stee l sintered specimen had a density of 7.27 g/cm3 , which decreased slightly with incr easing graphene content to 7.17 g/cm 3 for the sample with 0.5 wt.% graphene coating. The sintering temperature and graphene content appeared not to have significant effect on the microhardness. For instance, microhardness for the reference 316L sintered specimen was 189 HV, compared to ~ 171 HV fo r all the graphene-coated 316L sintered specimens. X-ray diffraction analysis did not dete ct the formation of carbides in the sintered samples, which suggested that the sintering pr ocess minimized its formation. Raman spectroscopy indicated that sintering at 850 °C preserved the structure of gr aphene during the spark plasma sintering process
Impact of dissolution of cast tungsten carbide on the wear behavior of CTC/Ni metal matrix composites
Cast tungsten carbide (CTC) consists in a biphasic structure of WC lamellae in a W2C matrix resulting from the eutectoid decomposition of W-3.9 wt.% C. Hardfacing of steel tools is the main industrial application of CTC powders, where metal matrix composite (MMC) wear-resistant overlays are deposited by means of conventional welding techniques. Self-fluxing nickel alloys are the most commonly used matrix materials for dispersed CTC particulate reinforcing phase. Overall performance and mechanical integrity of these overlays is affected by dissolution of CTC particles into the matrix phase due to high processing temperature. In this study, a powder blend containing 60 wt. % spherical CTC (71-150 μm) + 40 wt. % Ni-based matrix was used to deposit hardfacing overlays onto tool steel substrate by means of laser cladding. Scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS) revealed significant dissolution of WC into the surrounding matrix for all specimens. Reprecipitated W-rich carbide crystals ranged from fine and rather equiaxed for low energy input, to coarse and highly dendritic for high energy input. In a quest for completely avoiding dissolution of CTC particles, spark plasma sintering (SPS) was used to consolidate substrate-free CTC/Ni MMCs with significantly lower energy input and reasonably high cooling rate. SEM and EDS investigation of SPS-sintered MMCs revealed no WC dissolution followed by reprecipitation of W-rich carbides. Fracture toughness was estimated by means of microindentation fracture, and tribological testing was used to evaluate the impact of reprecipitated crystals on the wear behavior of CTC/Ni MMC’s
Modulating the import of medium-chain alkanes in E. coli through tuned expression of FadL
BACKGROUND: In recent years, there have been intensive efforts to develop synthetic microbial platforms for the production, biosensing and bio-remediation of fossil fuel constituents such as alkanes. Building predictable engineered systems for these applications will require the ability to tightly control and modulate the rate of import of alkanes into the host cell. The native components responsible for the import of alkanes within these systems have yet to be elucidated. To shed further insights on this, we used the AlkBGT alkane monooxygenase complex from Pseudomonas putida GPo1 as a reporter system for assessing alkane import in Escherichia coli. Two native E. coli transporters, FadL and OmpW, were evaluated for octane import given their proven functionality in the uptake of fatty acids along with their structural similarity to the P. putida GPo1 alkane importer, AlkL. RESULTS: Octane import was removed with deletion of fadL, but was restored by complementation with a fadL-encoding plasmid. Furthermore, tuned overexpression of FadL increased the rate of alkane import by up to 4.5- fold. A FadL deletion strain displayed a small but significant degree of tolerance toward hexane and octane relative to the wild type, while the responsiveness of the well-known alkane biosensor, AlkS, toward octane and decane was strongly reduced by 2.7- and 2.9-fold, respectively. CONCLUSIONS: We unequivocally show for the first time that FadL serves as the major route for medium-chain alkane import in E. coli. The experimental approaches used within this study, which include an enzyme-based reporter system and a fluorescent alkane biosensor for quantification and real-time monitoring of alkane import, could be employed as part of an engineering toolkit for optimizing biological systems that depend on the uptake of alkanes. Thus, the findings will be particularly useful for biological applications such as bioremediation and biomanufacturing
Cohort analysis of directly observed treatment outcomes for tuberculosis patients in urban Pakistan
Background: This quasi-experimental cohort study aimed to evaluate World Health Organization (WHO) defined tuberculosis (TB) treatment outcomes for Patients under directly observed treatment at a health facility (clinic DOT) or at home (family DOT) in urban Pakistan. Methods: We enrolled 582 sputum smear-positive TB Patients being treated by either clinic DOT (n = 295) or family DOT (n = 287) in 11 treatment centres. Patients and/or family members were interviewed for baseline measurements. WHO-defined treatment outcomes were evaluated at the end of treatment. Proportions of \u27cured\u27 Patients were computed. A log-binomial model was used to evaluate the associations of various factors with \u27cured\u27 status. Results: The proportion of \u27cured\u27 Patients was respectively 66% and 34% in the clinic DOT and family DOT groups (risk difference 0.32, 95%CI 0.24-0.39). Patients on clinic DOT were more likely to achieve cure (adjusted relative risk [RR(adj)] 1.85, 95%CI 1.43-2.39) than those on family DOT, as were Patients satisfied with their health care worker\u27s attitude (RR(adj) 5.73, 95%CI 2.54-12.96). Conclusion: Clinic DOT nearly doubled the proportion of cured Patients compared to family DOT. Efforts to improve care-provider attitudes to enhance Patient satisfaction, and effective implementation of the WHO\u27s public-private mix approach, may enhance TB control in this and similar settings
Representation of South Asian countries in five high-impact anesthesia journals
Context: The South Asian region is comprised of eight countries, i.e., Pakistan, India, Bangladesh, Sri Lanka, Afghanistan, Bhutan, Nepal, and Maldives. There is dearth of literature documenting anesthesia research in this region.Aim: The aim of this audit was to look at research productivity in the region by examining the volume and the type of anesthesia publication in five high-index anesthesia journals.Settings and Design: The study design was a survey of literature in the top five high-impact anesthesiology journals carried out at a tertiary care hospital.Materials and Methods: The journal citation report 2016 was accessed to identify the top five anesthesia journals based on their impact factor. We identified articles published in these journals between January 2000 and December 2015.Statistical Analysis: Microsoft Excel 2003 worksheet was used for data collection from extracted articles.Results: The highest number of publications came from India (n = 487) 95.9%; 58.5% of these were correspondence, 21% were original articles, 12.8% were case reports and case series, 1.2% reviews, and 1% editorials. Fourteen articles were published from Pakistan, with 1.2% original articles, 0.8% letter to editor, 0.6% audits, and 0.2% case reports. Nepal and Sri Lanka contributed seven publications. There were no publications in these journals from authors from Bangladesh, Afghanistan, Bhutan, and Maldives in the reviewed journals. The highest number of publications was equally distributed between two journals, i.e., Anesthesia and Analgesia (29.5%) and Anesthesia (28.9%).Conclusion: We found that scientific contributions from the South Asian region in terms of original anesthesiology research in five high index anesthesiology journals was suboptimal and has not shown an increasing trend over the last 16 years
A review of comparison of complications of vaginal hysterectomy with and without concomitant surgery for SUI: A 5 years’ experience at a tertiary care hospital of Pakistan
Objective. The study was performed to review the complications of surgery for POP with or without surgery for SUI. This included the need for second procedure two years after the primary surgery. Study Design. We conducted a retrospective cross-sectional comparative study at the Aga Khan University, Karachi, Pakistan. International Classification of Diseases, 9th revision, Clinical Modification (ICD-9-CM) was used to identify women who underwent vaginal hysterectomy with anterior/posterior repair alone and those with concomitant tension-free vaginal tape surgery for urodynamic stress incontinence. Results. The 28 cases of VH/repair combined with TVT were compared for complications with 430 cases of VH with repair alone. The basic characteristics like age, BMI, and degree of prolapse showed no statistical difference among two groups. The main comorbidities in both groups were hypertension, diabetes, and bronchial asthma. We observed no significant differences in intraoperative and postoperative complications except for cuff abscess, need for medical intervention, and readmission following discharge from hospital, which were higher in cases with vaginal hysterectomy with concomitant TVT. Conclusions. Vaginal hysterectomy is an efficient treatment for uterovaginal prolapse with a swift recovery, short length of hospital stay, and rare serious complications. The addition of surgery for USI does not appear to increase the morbidity
Injection use in two districts of Pakistan: implications for disease prevention
Objective. To estimate the annual number of injections per person in Sindh province of Pakistan and to describe their distribution with regard to prescribers, settings, and safety. Design. A population-based cross-sectional study in July-September 2001. Setting. Lyari, an urban town in Karachi district; and Digri, a rural subdistrict in Mirpur Khas district. Study participants. We selected a population-based cluster sample of 1150 individuals aged ≥3 months. We interviewed one person per household for the number of encounters they had with health care providers, number and types of injections received, safety circumstances, and cost of injections during the past 3 months. Main outcome measure. The number of injections per person per year. Results. After adjusting for age and sex, 68% of participants had received at least one injection in the previous 3 months (13.6 injections/person/year). The majority of the respondents received injections at the clinics of qualified general practitioners (n = 571, 67%) by dispensers (644, 76%). Most of the injections (n = 3446, 96%) were for curative purposes. A freshly opened syringe was used for only 454 (53%) of the injections. The average fee for receiving an injection was Rs. 51 (US$0.8). Conclusion. Injections are overused in Pakistan's Sindh province and the ratios of injection per capita that we found are among the highest ever reported. Interventions are needed to substantially reduce injection prescription among private health care providers who prescribe most of the injections received by the populatio
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The ‘common sense’ memory belief system and its implications
Memory experts, the police, and the public, completed a memory questionnaire containing a series of statements about autobiographical memory. The statements covered issues such as the nature of memory, determinants of accuracy, the relation of emotion and trauma to memory, and respondents indicated their agreement/disagreement with each of the statements. The police and public were found to share a ‘common sense’ memory belief system (CSMBS) in which memories were like videos/photographs, and accuracy was determined by the number of details recalled and also by their vividness. In direct contrast the scientific memory belief system, held by memory researchers, largely based on scientific evidence, was the opposite of the CSMBS and memories were judged to be fragmentary, number of details and their nature did not predict accuracy, and memories and their details could be in error and even false. The problematic nature of the CSBMS, which is pervasive in society, in raising the probability of flawed judgments of memory evidence is considered and, by way of illustration, applied to the (very high) attrition rate in complaints of rape
Genotoxic damage in cultured human peripheral blood lymphocytes of oral contraceptive users
Synthetic progestins and estrogens have been reported to be toxic in various experimental models. Their prolonged use has been reported to induce cancer in humans. In the present study the effects of oral contraceptives were studied among users using chromosomal aberrations, sister chromatid exchanges and DNA damage as a parameter, in cultured human peripheral blood lymphocytes. The study was performed on 25 women (users) and 25 age match controls. No significant difference was observed in chromosomal aberrations and DNA damage. A significant increase was observed in sister chromatid exchanges (SCEs) Cell among users. The results obtained and the risk of oral contraceptives (OCs) genotoxicity have been discussed.Keywords: Oral contraceptives; Chromosomal aberrations; DNA damage; Sister chromatid exchanges; Human lymphocyte
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