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A study has been conducted on the microbiology of sheep carcasses processed in a modern abattoir. The data revealed that careful handling at the different stages of processing of sheep reduced the level of microbial contamination of carcasses. Processing steps such as evisceration and washing did not increase the microbial counts on the carcass surface. Sources of microbial contamination in the abattoir were examined. It was observed that skin, floor washings, intestinal contents and gambrels were the major sources of microbial contamination. Seasonality did not have any effect on the microbial contamination of carcasses. The study revealed that total plate counts in 86·6% of the carcasses ranged between 3·0–4·9log/cm2. The counts of coliforms, staphylococci, enterococci and psychrotrophs were low. Pathogens such as Salmonella were not detected. The microbial counts were well within the generally acceptable levels. These findings demonstrated hygienic handling of carcasses. Shoulder and neck are the critical points for microbiological sampling as these sites showed higher microbial counts. Micrococcus and Staphylococcus predominated among microorganisms associated with carcasses. It was noted that differences occurred in microbial types of carcasses processed in tropical and temperate climates. The data generated in a model facility procided useful information for improving meat handling practices. 相似文献
3.
The forced convective heat transfer characteristics for incompressible power-law fluids past a bundle of circular cylinders have been investigated numerically. The cylinder-to-cylinder hydrodynamic interactions have been approximated via a simple cell model. The momentum and energy equations have been solved using a finite difference based numerical method for a range of physical and kinematic conditions. The role of the two commonly used thermal boundary conditions, namely, constant temperature or constant heat flux, on heat transfer characteristics has also been studied. Extensive numerical results elucidating the effect of shear-thinning viscosity on the values of Nusselt number have been obtained for Peclet numbers ranging from 1 to 5000, Reynolds number in the range 1-500, flow behaviour index 1?n?0.5 and three values of voidages, namely, 0.4, 0.5 and 0.6, typical of tubular heat exchangers and tube banks. Under all conditions, varying levels of enhancement in Nusselt number are observed due to shear-thinning behaviour. The surface averaged Nusselt number shows strong dependence on the values of voidage, power-law index, Reynolds and Peclet numbers. The paper is concluded by presenting comparisons with the scant experimental results available in the literature. 相似文献
4.
We present a machine learning tool for automatic texton-based joint classification and segmentation of mitochondria in MNT-1 cells imaged using ion-abrasion scanning electron microscopy (IA-SEM). For diagnosing signatures that may be unique to cellular states such as cancer, automatic tools with minimal user intervention need to be developed for analysis and mining of high-throughput data from these large volume data sets (typically ). Challenges for such a tool in 3D electron microscopy arise due to low contrast and signal-to-noise ratios (SNR) inherent to biological imaging. Our approach is based on block-wise classification of images into a trained list of regions. Given manually labeled images, our goal is to learn models that can localize novel instances of the regions in test datasets. Since datasets obtained using electron microscopes are intrinsically noisy, we improve the SNR of the data for automatic segmentation by implementing a 2D texture-preserving filter on each slice of the 3D dataset. We investigate texton-based region features in this work. Classification is performed by k-nearest neighbor (k-NN) classifier, support vector machines (SVMs), adaptive boosting (AdaBoost) and histogram matching using a NN classifier. In addition, we study the computational complexity vs. segmentation accuracy tradeoff of these classifiers. Segmentation results demonstrate that our approach using minimal training data performs close to semi-automatic methods using the variational level-set method and manual segmentation carried out by an experienced user. Using our method, which we show to have minimal user intervention and high classification accuracy, we investigate quantitative parameters such as volume of the cytoplasm occupied by mitochondria, differences between the surface area of inner and outer membranes and mean mitochondrial width which are quantities potentially relevant to distinguishing cancer cells from normal cells. To test the accuracy of our approach, these quantities are compared against manually computed counterparts. We also demonstrate extension of these methods to segment 3D images obtained using electron tomography. 相似文献
5.
An improved analytical model for the current-voltage (I-V) characteristics of the 4H-SiC metal semiconductor field effect transistor (MESFET) on a high purity semi-insulating (HPSI) substrate with trapping and thermal effects is presented. The 4H-SiC MESFET structure includes a stack of HPSI substrates and a uniformly doped channel layer. The trapping effects include both the effect of multiple deep-level traps in the substrate and surface traps between the gate to source/drain. The self-heating effects are also incorporated to obtain the accurate and realistic nature of the analytical model. The importance of the proposed model is emphasised through the inclusion of the recent and exact nature of the traps in the 4H-SiC HPSI substrate responsible for substrate compensation. The analytical model is used to exhibit DC I-V characteristics of the device with and without trapping and thermal effects. From the results, the current degradation is observed due to the surface and substrate trapping effects and the negative conductance introduced by the self-heating effect at a high drain voltage. The calculated results are compared with reported experimental and two-dimensional simulations (Silvaco®-TCAD). The proposed model also illustrates the effectiveness of the gate-source distance scaling effect compared to the gate-drain scaling effect in optimizing 4H-SiC MESFET performance. Results demonstrate that the proposed I-V model of 4H-SiC MESFET is suitable for realizing SiC based monolithic circuits (MMICs) on HPSI substrates. 相似文献
6.
Golla Narasimha Ayla Sridevi Golla Ramanjaneyulu 《International Journal of Food Properties》2016,19(3):652-661
Aspergillus niger, an isolate of soil contaminated with effluents from cotton ginning mill was grown in Czapek-Dox medium containing sawdust, Triton-X 100 and urea for production of an extracellular β-glucosidase. β-Glucosidase enzyme was purified (86-fold) from culture filtrate of A. niger by employing ammonium sulphate precipitation and gel filtration on sephadex G-75. The molecular mass of the purified enzyme was estimated to be 95 kDa by sodium dodecyl sulphate polyacrylamide gel electrophoresis. The enzyme had an optimal activity on p-nitrophenyl β-D-glucopyranoside at 50°C and pH 5.0. The Km and Vmax of the enzyme on p-nitrophenyl β-D-glucopyranoside at 50°C and pH 5 were 8.0 mM and 166 µmol/min/mg of protein, respectively. The enzyme could hydrolyze cellobiose and lactose but not sucrose. Heavy metals like Hg2+, Al3+, and Ag+ inhibited the activity, whereas Zn2+ and detergents such as Triton-X 100 and Tween-80 increased the activity at 0.01%. The enzyme activity increased in the presence of methanol and ethanol. 相似文献
7.
Moisture diffusion through (hexadecyltrimethylammonium bromide ‐ Indian bentonite)/(vinylester) nanocomposites in artificial seawater and demineralized water 下载免费PDF全文
N. Raghavendra H. N. Narasimha Murthy Salim Firdosh R. Sridhar Gangadhar Angadi K. R. Vishnu Mahesh M Krishna 《乙烯基与添加剂工艺杂志》2016,22(4):441-451
This paper compares the moisture diffusion properties of organomodified (Indian Bentonite nanoclay)/vinylester containing different amounts of nanoclay on exposure to demineralized water and artificial seawater at room temperature. Moisture uptake behavior of (Indian Bentonite)/vinylester was investigated and compared with that of neat vinylester. Addition of 5 wt% nanoclay decreased the diffusivity and permeability of vinylester in artificial seawater medium, but these diffusion parameters increased in demineralized water medium. Degradation in glass transition temperature and microhardness of the nanocomposites were much greater in specimens aged in demineralized water than in those in artificial seawater medium. Moisture diffusion behavior of the specimens was analyzed by Fick's law and the Langmuir model. The aged specimens were chemically analyzed by using infrared spectroscopy after aging for 146 days. A significant amount of leached organic species was detected in the demineralized water–aged specimens but the same was absent in those aged in artificial seawater. J. VINYL ADDIT. TECHNOL., 22:441–451, 2016. © 2015 Society of Plastics Engineers 相似文献
8.
In the present work, the shell and tube heat exchanger (STHX) is designed based on The Tubular Exchanger Manufacturers Association standards with hot fluid (water) flowing on the shell side and cold fluid on the tube side. A comparison is made between the Nusselt number and friction factor obtained from numerical and experimental results of segmental baffles (SBs) and helical baffles (HB) with different baffle inclinations. The results show that SB provided a higher Colburn factor (js) when compared with HBs STHXs (20°, 30°, 40°, and 50°), but shell side pressure drop is lower for 40° HBs STHXs for the same shell side fluid flow rates. 相似文献
9.
C. S. Naveen P. Raghu H. M. Mahesh K. Narasimha Rao R. Rakesh Kumar A. R. Phani 《稀有金属(英文版)》2014,33(5):578-582
TiO2thin films with 0.2 wt%, 0.4 wt%, 0.6wt%, and 0.8 wt% Fe were prepared on glass and silicon substrates using sol–gel spin coating technique. The optical cut-off points are increasingly red-shifted and the absorption edge is shifted over the higher wavelength region with Fe content increasing. As Fe content increases, the optical band gap decreases from 3.03 to 2.48 eV whereas the tail width increases from 0.26 to 1.43 eV. The X-ray diffraction(XRD) patterns for doped films at 0.2 wt% and0.8 wt% Fe reveal no characteristic peaks, indicating that the film is amorphous whereas undoped TiO2exhibits(101) orientation with anatase phase. Thin films of higher Fe content exhibit a homogeneous, uniform, and nanostructured highly porous shell morphology. 相似文献
10.
D.V.N. Harish A. Bharatish H.N. Narasimha Murthy B. Anand K.N. Subramanya 《Ceramics International》2021,47(3):3498-3513
Laser ablation of high-temperature ceramic coatings results in thermal residual stresses due to which the coatings fail by cracking and debonding. Hence, the measurement of such residual stresses during laser ablation process holds utmost importance from the view of performance of coatings in extreme conditions. The present research aims at investigating the effect of laser parameters such as laser pulse energy, scanning speed and line spacing on thermal residual stresses induced in tantalum carbide-coated graphite substrates. Residual stresses were measured using micro-Raman spectroscopy and correlated with Raman peak shifts. Transient thermal analysis was performed using COMSOL Multiphysics to model the single ablated track and residual stresses were reported at low, moderate and high pulse energy regimes. The results showed that the initial laser conditions caused higher tensile residual stresses. Moderate pulse energy regime comprised higher compressive residual stresses due to off centre overlapping of the laser pulses. Higher pulse energy (250 μJ), higher scanning speed (1000 mm/s) and moderate line spacing (20 μm) caused accumulation of tensile residual stresses during the final stage of laser ablation. The deviation of experimental residual stresses from COMSOL numerical model was attributed to unaccounted additional stresses induced during thermal spraying process and deformation potentials in the numerical model. 相似文献