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201.
Dharmendra Tripathi 《仿生工程学报(英文版)》2012,9(1):119-131
A mathematical model is constructed to examine the characteristics of three layered blood flow through the oscillatory cylindrical tube (stenosed arteries).The proposed model basically consists three layers of blood (viscous fluids with different viscosities) named as core layer (red blood cells),intermediate layer (platelets/white blood cells) and peripheral layer (plasma).The analysis was restricted to propagation of small-amplitude harmonic waves,generated due to blood flow whose wave length is larger compared to the radius of the arterial segment.The impacts of viscosity of fluid in peripheral layer and intermediate layer on the interfaces,average flow rate,mechanical efficiency,trapping and reflux are discussed with the help of numerical and computational results.This model is the generalized form of the preceding models.On the basis of present discussion,it is found that the size of intermediate and peripheral layers reduces in expanded region and enhances in contracted region with the increasing viscosity of fluid in peripheral layer,whereas,opposite effect is observed for viscosity of fluid in intermediate layer.Final conclusion is that the average flow rate and mechanical efficiency increase with the increasing viscosity of fluid in both layers,however,the effects of the viscosity of fluid in both layers on trapping and reflux are opposite to each other. 相似文献
202.
Tripathi MK Mishra AS Misra AK Vaithiyanathan S Prasad R Jakhmola RC 《Letters in applied microbiology》2008,46(3):364-370
Aims: Selection of white‐rot fungi of bio‐conversion of mustard straw (MS) into feed for ruminants. Methods and Results: Mustard straw was cultured with Ganoderma applanatum, Coriolus versicolor and Phanerochaete chrysosporium for solid‐state fermentation at 35°C from 7 to 63 days for dilignification and for 21 days to study dry matter digestibility and protein enrichment. Lignin loss in fungus cultured straw varied between 100 and 470 g kg?1 lignin. Dilignification was higher between 7 and 28 days fermentation with C. versicolor. Among the three fungi P. chrysosporium was the most effective in degrading lignin for longer fermentation. In‐vitro dry matter digestibility (IVDMD) and crude protein content was higher in C. versicolor cultured straw. Large quantity of straw was cultured by C. versicolor for 21 days, for in vivo evaluation. Mean pH and metabolites of rumen fermentation were not different while, pH and volatile fatty acid increased at 6 h postfermentation on cultured straw feeding. Cultured straw fermentation increased (P = 0·001) small holotricks and reduced (P = 0·005) large holotricks population. Fungus cultures straw did not improve microbial enzyme concentration. Conclusions: Coriolus versicolor and P. chrysosporium were the promising fungus for MS bio‐dilignification. Significance and Impact of the Study: Coriolus versicolor treated MS improved dry matter digestibility and protein content. 相似文献
203.
Dee CT Hirst CS Shih YH Tripathi VB Patient RK Scotting PJ 《Developmental biology》2008,320(1):289-301
204.
Previous studies have shown that Cdk5 promotes lens epithelial cell adhesion. Here we use a cell spreading assay to investigate the mechanism of this effect. As cells spread, forming matrix adhesions and stress fibers, Cdk5(Y15) phosphorylation and Cdk5 kinase activity increased. Cdk5(Y15) phosphorylation was inhibited by PP1, a Src family kinase inhibitor. To identify the PP1-sensitive kinase, we transfected cells with siRNA oligonucleotides for cSrc and related kinases. Only cSrc siRNA oligonucleotides inhibited Cdk5(Y15) phosphorylation. Cdk5(pY15) and its activator, p35, colocalized with actin in stress fibers. To examine Cdk5 function, we inhibited Cdk5 activity under conditions that also prevent phosphorylation at Y15: expression of kinase inactive mutations Cdk5(Y15F) and Cdk5(K33T), and siRNA suppression of Cdk5. Stress fiber formation was severely inhibited. To distinguish between a requirement for Cdk5 kinase activity and a possible adaptor role for Cdk5(pY15), we used two methods that inhibit kinase activity without inhibiting phosphorylation at Y15: pharmacological inhibition with olomoucine and expression of the kinase inactive mutation, Cdk5(D144N). Stress fiber organization was altered, but stress fiber formation was not blocked. These findings indicate that Cdk5(Y15) phosphorylation and Cdk5 activity have distinct functions required for stress fiber formation and organization, respectively. 相似文献
205.
S. Ramachandra Rao Usha Tripathi G. A. Ravishankar 《Biocatalysis and Biotransformation》2002,20(2):137-143
Cell suspension cultures of Capsicum frutescens accumulated digoxin, purpureaglycoside A and other unknown derivatives when digitoxin, a cardiac glycoside, was used as a precursor. The feeding of digitoxin complexed with β-cyclodextrin increased the accumulation of digoxin, purpureaglycoside A and other unknown derivatives. Control cultures (without digitoxin) did not produce any of these metabolites. The growth of cells was affected by both digitoxin as well as digitoxin- β-cyclodextrin. The accumulation of purpureaglycoside A and digoxin reached a maximum of 1241 and 374 μg 100 ml -1 culture on the 6th and 2nd day, respectively, which was 3.9 and 4.5 fold higher than cultures treated with digitoxin alone (sampled on the 13th day). The other unknown derivatives formed in digitoxin- β-cyclodextrin fed cultures were 15 times higher than digitoxin alone fed C. frutescens cultures. The addition of glucose to digitoxin- β-cyclodextrin treated cultures increased the accumulation of purpureaglycoside A which reached a maximum of 3589 μg 100 ml -1 culture after 12 h incubation, which was a 2.9 fold increase over cultures treated with digitoxin- β-cyclodextrin alone. 相似文献
206.
Arun Kumar Tripathi Rajendra Singh Bhakuni Shikha Upadhyay Rashmi Gaur 《Insect Science》2011,18(2):189-194
Abstract Artemisia annua (Asteraceae) is well known for its antimalarial activities due to presence of the compound artemisinin. We isolated a methoxy coumarin from the stem part of A. annua and confirmed its identity as scopoletin through mass spectral data. The structure was established from 1H‐nuclear magnetic resonance (NMR), 13C‐NMR. The compound scopoletin was evaluated for its feeding deterrence and growth inhibitory potential against a noxious lepidopteran insect, Spilartctia obliqua Walker. Scopoletin gave FD50 (feeding deterrence of 50%) value of 96.7 μg/g diet when mixed into artificial diet. S. obliqua larvae (12‐day‐old) exposed to the highest concentration (250 μg/g diet) of scopoletin showed 77.1% feeding‐deterrence. In a growth inhibitory assay, scopoletin provided 116.9% growth inhibition at the highest dose of 250 μg/g diet with a GI50 (growth inhibition of 50%) value of 20.9 μg/g diet. Statistical analysis showed a concentration‐dependent dose response relationship toward both feeding deterrent and growth inhibitory activities. Artemisinin is found mainly in the leaves of A. annua and not in the stems, which are typically discarded as waste. Therefore identification of scopoletin in stems of A. annua may be important as a source of this material for pest control. 相似文献
207.
Md Aminul Islam Pratima Sinha Shyam Sundar Sharma Madan Singh Negi Bijoy Neog Shashi Bhushan Tripathi 《Plant Molecular Biology Reporter》2016,34(4):869-875
North eastern (NE) India harbours a precious germplasm repository of Capsicum in the form of various landraces. The present study was undertaken to characterise the extent of genetic variation present in different Capsicum landraces from north eastern India. A set of 171 Capsicum accessions were characterised using three-endonuclease amplified fragment length polymorphism (AFLP) markers. Out of 416 bands obtained from six primer combinations, 254 (61 %) were polymorphic. The pairwise genetic dissimilarity among accessions ranged from 0.03 to 0.97. Cluster analysis based on neighbour joining showed two major clusters. Cluster I contained most of the bhut jolokia accessions whereas cluster II contained all of the Capsicum annuum genotypes. Similar grouping was observed with population STRUCTURE analysis as well as principle coordinate analysis. Analysis of molecular variance (AMOVA) revealed 45 and 54 % variation among and within populations, respectively. This information on population structure analysis and molecular characterisation will be helpful for effective utilisation of this germplasm in Capsicum improvement programs. 相似文献
208.
209.
Durgesh Kumar Tripathi Vijay Pratap Singh Dharmendra Kumar Devendra Kumar Chauhan 《Acta Physiologiae Plantarum》2012,34(1):279-289
Hydroponic experiments were conducted to investigate the role of exogenous silicon (Si) addition in increasing hexavalent
chromium (Cr VI) tolerance in rice seedlings. Rice seedlings were grown under 100 μM Cr(VI) stress without or with 10 μM Si.
Chromium treatment decreased growth, photosynthetic pigments and protein, which was accompanied by a significant increase
in Cr accumulation and lipid peroxidation (as malondialdehyde; MDA). However, Si addition alleviated Cr toxicity and promoted
growth of rice by decreasing Cr accumulation, root-to-shoot Cr transport and MDA level. Contents of macro (Mg, Ca and K) as
well as micronutrients (Zn and Fe) were decreased by Cr except Mn while Si addition prevented decrease in these nutrients
induced by Cr. Antioxidant capacity and total phenolic contents were decreased by Cr while these indices improved by Si addition.
Treatment of Cr decreased the length of leaf epidermal cells and stomatal frequency, and adversely affected chloroplasts containing
mesophyll cells and integrity of xylem and phloem, and Si addition minimized these abnormalities. However, frequency of root
hairs was increased by Cr treatment. Results showed that exogenous Si addition enhanced Cr(VI) tolerance in rice seedlings
by decreasing Cr accumulation, root-to-shoot Cr transport and MDA level, and by increasing content of some mineral elements
(K, Fe and Zn) and antioxidant capacity compared to the Cr treatment alone. 相似文献
210.
Human influences on mobility of nitrogen in the environment: Needs for research and management 下载免费PDF全文
S.K. Tripathi 《农业工程》2009,29(2):130-135
Nitrogen (N) cycles through air, water and soil and plays an important role in the synthesis of complex N compounds in all forms of life on the planet earth by combining with carbon, hydrogen and oxygen (O). Besides, natural fixation of N by microorganisms, advertent and inadvertent fixation of N by human activities (e.g. landscape transformations, fossil fuel burning and use of N in agricultural fields) are altering the global cycle of N. As a result of human activities, N enters in water bodies (e.g. streams, estuaries and coastal regions) making them hostile for aquatic life and contaminates ground water (used for drinking) through nitrate (NO3-) leaching which causes a number of health problems to human beings and animals. Hence, reduction in level of NO3- in water bodies and ground water is a prerequisite that can be met through sustainable management of natural and modified ecosystems. More specifically, agricultural management practices need to be better designed to synchronize the availability of NO3- with that of the crop N demand. These management goals can be achieved by thorough understanding of the origin and fate of N, by using isotopic analysis of N and O in NO3-, which can provide the best management options for N in the environment. Overall, an integrated approach would be required to limit N production/use and release to prevent critical environmental limit being exceeded. 相似文献