Role of elasticity in control of diameter of electrospun PAN nanofibers     

Sandip Basu  Naminita Gogoi  Shilpi Sharma  Manjeet Jassal  Ashwini K. Agrawal 《Fibers and Polymers》2013,14(6):950-956

A series of poly(acrylonitrile-co-methylacrylate) copolymers (PAN) with varying molecular weight were synthesized by radical copolymerization using α-α′-azobisisobutyronitrile (AIBN) as initiator. These copolymers were dissolved at different concentrations in DMF and electrospun at Minimum electrospinning voltage (MEV) to correlate electrical energy required to perform the mechanical work during the spinning of the fibers. The diameters of the resultant fibers were correlated with the Berry number and average number of entanglements per chain of the spinning solution. It was observed that number of entanglements per chain, which represents the capacity of the polymer system to store elastic energy, could correlate well with the ultimate diameter of the fiber. Interestingly, the diameters of the nanofibers were found to increase linearly with increase in number of entanglements per chain with two distinct regions having transition of the slope at number of entanglement value of 3.5.  相似文献   

Application of fractal theory in assessing soil aggregates in Indian tropical ecosystems     

S. K. Tripathi  C. P. Kushwaha  S. K. Basu 《林业研究》2012,23(3):355-364

Soil aggregation varies according to climatic and management factors, and is difficult to measure because of irregular shapes and sizes of soil aggregates. We applied fractal theory to assess soil aggregation as affected by (1) land use change from forest to savanna, (2) nutrient additions in forest, ecotone, and savanna ecosystems, and (3) tillage practice and residue treatments in an agro-ecosystem. We used fractal dimensions nonlinear (Dnon-lin) and linear (Dlin) based on number of aggregates (N) and mass of aggregates (M) (the range of values were 2.6 2.89 and 2.69 3.41, respectively) to capture the variations in the sizesof soil aggregates due to land use and treatments/management in these ecosystems. The variation in the values of nonlinear fractal dimension based on mass (DMnon-lin) was smaller in forest and savanna ecosystems with and without nutrient additions, while the variation was wider inagro-ecosystems with different management practices. Linear fractal dimensions based on number (DNlin) and mass (DMlin) of aggregates varied marginally in these ecosystems and did not capture the variations insoil aggregates well. The variations in nonlinear fractal dimension indicate that continued nitrogen loading in forest accelerates the formation of macroaggregates, whereas in savanna the situation was reversed. The values of nonlinear fractal dimensions did not show significant change after 6 years of nutrient additions in the ecotone; reflecting a buffering mechanism of this system in soil aggregate formation. On the basis of non-linear fractal dimension values, we conclude that residue retention and minimum tillage are appropriate for proper maintenance of soil aggregate stability for sustained crop production in the Indian dry land agro-ecosystems.  相似文献   

Analysis of coat protein gene sequences of begomoviruses associated with different weed species in India     

Sujay Paul  Raju Ghosh  Anirban Roy  Subrata Kumar Ghosh 《Phytoparasitica》2012,40(1):95-100

Sida cordifolia L., Croton bonplandianum L., Malachra capitata L., Eclipta prostrata L., Clerodendron inerme L., Acalypha indica L., and Urena lobata L. are common weeds found all over India. They are often infected by different begomovirus complexes and may act as reservoirs of crop-infecting begomoviruses. Cloning and sequencing were done to partially characterize the begomovirus complexes associated with these weed species from the eastern part of India and their genetic pattern was compared with respective geographical isolates throughout India. Coat protein (CP) genes were found to be amplified from all the infected samples tested in this study, whereas betasatellite molecules amplified only from four infected samples (Sida, Croton, Malachra and Urena). Sequence analysis using CP genes and betasatellites of the present begomovirus complexes showed significant variation among their geographical isolates and also exhibited closeness to different crop-infecting begomovirus complexes. The majority of the weed-infecting begomovirus complexes characterized in this paper are reported for the first time from India.  相似文献   

Studies on the etiology and pathogenesis of endocardiosis and endocarditis in the dog. 3. Microbiological findings     

H Kirchhoff  G Amtsberg  W Bisping  A Basu 《DTW. Deutsche tier?rztliche Wochenschrift》1973,80(18):428-32 contd

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Etiology and pathogenesis of endocardiosis and endocarditis in dogs. 3. Microbiological results     

H Kirchhoff  G Amtsberg  W Bisping  A Basu 《DTW. Deutsche tier?rztliche Wochenschrift》1973,80(19):445-446

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Quantification of ToxB gene expression and formation of appressoria by isolates of Pyrenophora tritici-repentis differing in pathogenicity     

S. Amaike  J. A. Ozga  U. Basu  S. E. Strelkov 《Plant pathology》2008,57(4):623-633

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Abiotic stresses,constraints and improvement strategies in chickpea     

Uday C. Jha  Sushil K. Chaturvedi  Abhishek Bohra  Partha S. Basu  Muhammad S. Khan  Debmalya Barh 《Plant Breeding》2014,133(2):163-178

Chickpea (Cicer arietinum L.) is cultivated mostly in the arid and semi‐arid regions of the world. Climate change will bring new production scenarios as the entire growing area in Indo–Pak subcontinent, major producing area of chickpea, is expected to undergo ecological change, warranting strategic planning for crop breeding and husbandry. Conventional breeding has produced several high‐yielding chickpea genotypes without exploiting its potential yield owing to a number of constraints. Among these, abiotic stresses include drought, salinity, water logging, high temperature and chilling frequently limit growth and productivity of chickpea. The genetic complexity of these abiotic stresses and lack of proper screening techniques and phenotyping techniques and genotype‐by‐environment interaction have further jeopardized the breeding programme of chickpea. Therefore, considering all dispiriting aspects of abiotic stresses, the scientists have to understand the knowledge gap involving the physiological, biochemical and molecular complex network of abiotic stresses mechanism. Above all emerging ‘omics’ approaches will lead the breeders to mine the ‘treasuring genes’ from wild donors and tailor a genotype harbouring ‘climate resilient’ genes to mitigate the challenges in chickpea production.  相似文献   

Study on the packing density of structurally modified ring spun yarn     

Sujit Kumar Sinha  Pawan Kumar  Subrata Ghosh 《Fibers and Polymers》2016,17(11):1898-1907

Fibres being the structural unit of a yarn, its nature, composition and arrangement can influence structure and properties. The performance of yarn changes with arrangement of its constituent fibres. Arrangement of fibres in a yarn being system specific, different spinning system results different arrangement of fibres causing variation in product performance. A change in the arrangement of fibres in an already formed yarn can be brought about by suitable physical and/or chemical treatment. A treatment to remove a component is expected to cause changes in final arrangement of fibres in a yarn. In the present study, polyester/PVA blended yarn was modified through dissolution of the later component. The resultant change in structural arrangement on dissolution was assessed by the change in radial packing distribution of fibres. Migration index, helped in identifying the location that was influenced more in the redistribution. In the parent yarn, PVA had a preferential tendency to predominate near the core. On dissolution of PVA, creation of open space was expected and collapsing of the structure led to a possible rearrangement of fibres and reduction in diameter of yarn. Fibre denier, blend ratio and twist factor were also found to influence packing density both in parent and modified yarn. Unlike published reports, interestingly, an increase in fibre packing density was observed on dissolution of PVA. Average packing density in parent yarn was found to lie at a yarn radius between 0.07 mm to 0.09 mm while for the modified yarn it was between 0.05 mm to 0.07 mm.  相似文献   

Differential behaviour of sheath blight pathogen Rhizoctonia solani in tolerant and susceptible rice varieties before and during infection          下载免费PDF全文

A. Basu  S. Chowdhury  T. Ray Chaudhuri  S. Kundu 《Plant pathology》2016,65(8):1333-1346

This study characterized the early infection and establishment of the sheath blight pathogen Rhizoctonia solani on a tolerant rice variety, Swarnadhaan (IET 5656), and a susceptible variety, Swarna (MTU 7029). Assays using whole plants showed that disease severity was higher in Swarna than Swarnadhaan. In a detached leaf assay, Swarnadhaan showed a disease index that was 50% less than that with Swarna. Rhizoctonia solani exhibited different growth behaviour in the tolerant and susceptible varieties. The pathogen showed more hyphal growth in the susceptible host than in the tolerant variety. It also showed profuse branching, making intimate contact with the host surface to form more inter‐ and intracellular structures, and greater sclerotial development in the susceptible host compared to the tolerant one. Using light and scanning electron microscopy, it was observed for the first time that the pathogen could intercept host surface structures and use these for anchorage or penetration. Transformed R. solani, expressing green fluorescent protein, was observed using confocal laser scanning microscopy to investigate pathogen behaviour, including the formation of infection cushions and subsequent colonization of the host tissues. This is the first ultrastructural report to characterize the differential behaviour of the sheath blight pathogen in the vicinity and within tolerant and susceptible rice plants.  相似文献   

Seed treatment for viability,vigour and productivity of tomato     

R. Mitra  R.N. Basu 《Scientia Horticulturae》1979,11(4):365-369

Soaking—drying treatment of stored tomato seeds greatly reduced their deterioration under accelerated and natural ageing conditions. Hydration by moisture equilibration at 100% RH for 24 hours followed by drying-back was also very effective. Treatment of harvest-fresh seed was ineffective. The beneficial effects of the soaking—drying treatments were reflected in the productivity of the crop. Treatment with dilute solutions of sodium chloride (10^?3 M) or sodium phosphate (dibasic, 10^?4 M) proved better than water for field performance and productivity.  相似文献