3,333 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
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
COMPARATIVE PRODUCTIVE PERFORMANCE AND EGG CHARACTERISTICS OF PULLETS AND SPENT LAYERS
Production performance and egg quality characteristics of pullets and spent layers were compared in this study. Forty birds, each from the flocks of pullets (24 weeks old) and spent layers (76 weeks old) were selected as experimental birds. The birds from each age group were divided into five replicates, each comprising of eight birds. All the experimental birds were fed a commercial layer ration @ 110g/bird/day for 12 weeks. The data on egg production, feed consumption, egg weight and egg quality characteristics viz. shell thickness, shell weight, breaking strength, albumen diameter, albumen weight and yolk weight were recorded. The data thus collected were utilized for calculation of FCR, Haugh unit and yolk index values. The results revealed that pullets produced more eggs and utilized their feed more efficiently than spent layers. However, egg weight in spent layers was higher than in their counterparts. Pullets also produced eggs with thicker shell and higher Haugh unit values when compared to the spent layers. Feed consumption and yolk index values remained unaffected due to the age. Pullets also had better egg quality characteristics than those of spent layers
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
Influence of plasma treatment on SiO2/Si and Si3N4/Si substrates for large-scale transfer of graphene
One of the limiting factors of graphene integration into electronic, photonic, or sensing devices is the unavailability of large-scale graphene directly grown on the isolators. Therefore, it is necessary to transfer graphene from the donor growth wafers onto the isolating target wafers. In the present research, graphene was transferred from the chemical vapor deposited 200 mm Germanium/Silicon (Ge/Si) wafers onto isolating (SiO2/Si and Si3N4/Si) wafers by electrochemical delamination procedure, employing poly(methylmethacrylate) as an intermediate support layer. In order to influence the adhesion properties of graphene, the wettability properties of the target substrates were investigated in this study. To increase the adhesion of the graphene on the isolating surfaces, they were pre-treated with oxygen plasma prior the transfer process of graphene. The wetting contact angle measurements revealed the increase of the hydrophilicity after surface interaction with oxygen plasma, leading to improved adhesion of the graphene on 200 mm target wafers and possible proof-of-concept development of graphene-based devices in standard Si technologies
EFFECTS OF LOCAL GAMETOCYTE AND LIVACOX VACCINES ON LIVE BODY WEIGHT GAIN AND LYMPHOID ORGANS IN CHICKENS
Organ to body weight ratio in chickens is considered to be an important parameter to study the immune status due to any infection or vaccination. The present paper reports the effects of local gametocyte and Livacox vaccines on live weight gains and lymphoid organs in chickens. The mean body weight gains in chickens with local gametocytes vaccine were significantly better (P<0.05) than in chickens with Livacox vaccine. Higher organ to body weight ratio was recorded in vaccinated chickens compared to control, although difference was non significant. Organ to body weight ratio of the lymphoid organs had higher values in chickens vaccinated with Livacox compared to local gametocyte vaccinated group, the difference was also found to be non significant. It was concluded that local gametocyte vaccine significantly increased the body weights of chickens compared to Livacox and control groups
Author Correction: Influence of plasma treatment on SiO2/Si and Si3N4/Si substrates for large-scale transfer of graphene
The original version of this Article omitted an affiliation for M. Lisker. The correct affiliations for M. Lisker are listed below: IHP- Leibniz Institut für innovative Mikroelektronik, Im Technologiepark 25, 15236, Frankfurt (Oder), Germany Technical University of Applied Science Wildau, Hochschulring 1, 15745, Wildau, Germany The original Article and accompanying Supplementary Information file have been corrected
Sonographic fetal biometry charts for a Pakistani cohort.
This study aimed to develop growth centiles at different gestational weeks for fetal biparietal diameter, abdominal circumference, femur length and head circumference in a Pakistani cohort. Data were collected at a tertiary referral hospital from pregnant women at gestational ages 13-40 weeks referred for obstetric ultrasound as a part of routine antenatal care. A total of 1599 fetal sonographic biometric measurements were collected after screening for the inclusion criteria. For each measurement, separate regression models were derived to estimate the mean, standard deviation and reference percentiles at each week of gestational age for this cohort. The best fitting model for each variable was selected. These charts will help radiologists and clinicians in predicting dates of delivery, assessing fetal growth and identifying intrauterine fetal insufficiency in the Pakistani population
The evaluation of hepatocellular carcinoma with biphasic contrast enhanced helical CT scan
Objective: To evaluate the role of biphasic contrast-enhanced helical CT including Hepatic Arterial Phase (HAP) imaging with Portal Venous Phase (PVP) imaging, in the detection and characterization of hepatocellular carcinomas.Methods: The study included 40 patients (M = 26, F = 14) with histopathologically proven HCC. Age range was between 30-85 years (mean = 55) by following consecutive patients with cirrhosis in whom Hepatocellular carcinoma was diagnosed or suspected either by raised serum a (alpha)-fetoprotein level or Ultrasound.Results: Biphasic contrast-enhanced examination revealed a total of 85 lesions in these 40 patients, out of which 13 were unifocal, 12 showed a dominant mass with satellite lesions, 2 showed cluster of contiguous nodules and 13 were multifocal HCCs. Mean diameter was 3.1 cm, ranging from 0.8 to 14 cm. On HAP imaging 85% were detected. (hyperattenuating = 69, hypoattenuating = 3) while on PVP imaging detectibility was only 48% (hyperattenuating = 2, hypoattenuating = 39). Hence detectibility was significantly (p = 0.008) superior in HAP as compared to PVP imaging. In 7 patients (17%) tumor was visible only on HAP images. Venous invasion was present in 12 patients (30%) while arterio-portal shunting was seen in 5 patients (13%).CONCLUSION: Biphasic contrast enhanced helical CT is a useful method in detection and characterization of HCC
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