检索结果-南通市图书馆

Properties of boron doped ZnO films prepared by reactive sputtering method: Application to amorphous silicon thin film solar cells

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2020年第20期52卷 136-143页

作者： Sukanta Bose Sourav Mandal asok k.Barua Sumita Mukhopadhyay Centre of Excellence for Green Energy and Sensor Systems Indian Institute of Engineering Science and TechnologyShibpurHowrah 711103West BengalIndia Centre for Energy Studies Indian Institute of Technology DelhiNew Delhi 110016India

Reactive sputtered boron-doped zinc oxide(BZO) film was deposited from argon,hydrogen and boron gas *** reactive sputtering technique provides us the flexibility of changing the boron concentration in the produced films by using the same intrinsic zinc oxide *** surface was obtained in the as-deposited *** surface morphology and the opto-electronic properties of the films can be controlled by simply varying the gas concentration *** varying the gas concentration ratio,the best obtained resistivity ~6.51×10^-4Ω-cm,mobility ~19.05 cm^2 V^-1 s^-1 and sheet resistance ~7.23Ω/□ were *** lower wavelength of light,the response of the deposited films improves with the increase of boron in the gas mixture and the overall transmission in the wavelength region 350-1100 nm of all the films are>85 %.We also fabricated amorphous silicon(a-Si) thin film solar cell on the best obtained BZO *** overall efficiency of the a-Si solar cell is 8.14 %,found on optimized BZO layer.

关键词： Magnetron reactive sputtering BZO Amorphous silicon Solar cells Zinc oxide(ZnO)

Sperm immobilization activity of Allium sativum L. and other plant extracts

在线全文

学校读者我要写书评

暂无评论

Asian Journal of Andrology 2003年第2期5卷 131-135页

作者： kausiki Chakrabarti Sulagna Pal asok k.Bhattacharyya Reproductive Biology Laboratory Department of Biochemistry University of Calcutta Calcutta-700 019 IndiaReproductive Biology Laboratory Department of Biochemistry University of Calcutta Calcutta-700 019 IndiaReproductive Biology Laboratory Department of Biochemistry University of Calcutta Calcutta-700 019 India

Aim: To identify possible spermicidal agents through screening a number of edible medicinal plants with antimicrobial activity. Methods: Initial screening was made on the basis of ram cauda epididymal sperm immobilization immediately after addition of extracts. The most potent extract was selected and was evaluated on both ram and human spermatozoa. To unravel its mode of action several sperm functional tests were carried out, namely viability of cells, hypo-osmotic swelling test for membrane integrity and assays of membrane-bound enzyme 5'-nucleotidase and acrosomal marker enzyme acrosin. Results: The crude aqueous extract of the bulb of Allium sativum L. showed the most promising results by instant immobilization of the ram epididymal sperm at 0.25 g/mL and human ejaculated sperm at 0.5 g/mL. Sperm immobilizing effects were irreversible and the factor of the extract responsible for immobilization was thermostable up to 90 癈. On boiling at 100 癈 for 10 minutes, this activity was markedly reduced. Moreover, this extract was able to cause aggregation of ram sperms into small clusters after 30 minutes of incubation at 37 癈. However this property was not found in human spermatozoa. More than 50 % reduction in sperm viability and hypo-osmotic swelling occurred in treated sperm as compared with the controls, indicating the possibility of plasma membrane disintegration which was further supported by the significant reduction in the activity of membrane bound 5'-nucleotidase and acrosomal acrosin. Conclusion: The crude aqueous extract of A. sativum bulb possesses spermicidal activity in vitro.

关键词： Allium sativum plant extracts sperm immobilization farm animals ram human spermicidal agents thermostability

Prediction of oil-water flow patterns, radial distribution of volume fraction, pressure and velocity during separated flows in horizontal pipe

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2016年第4期28卷 658-668页

作者： Anand B.DESAMALA Vinayak VIJAYAN Anjali DASARI Ashok kumar dasmahapatra Tapas k.MANDAL Department of Chemical Engineering Indian Institute of Technology Guwahati

Flow of two immiscible fluids gives rise to variety of flow patterns,which influence transportation *** this work,we present detailed analysis on the prediction of flow pattern maps and radial distribution of volume fraction,pressure and velocity of a pair of immiscible liquids through a horizontal pipeline by computational fluid dynamics（CFD） simulation using ANSYS FLUENT *** viscous oil and water have been taken as the fluid pair for *** of fluid（VOF） method has been employed to predict various flow patterns by assuming unsteady flow,immiscible liquid pair,constant liquid properties,and co-axial *** the grid independent study,we have selected 47 037 number of quadrilateral mesh elements for the entire *** successfully predicts almost all the flow patterns（viz.,plug,slug,stratified wavy,stratified mixed and annular）,except dispersion of oil in water and dispersion of water in *** simulated results are validated with experimental results of oil volume fraction and flow pattern *** distribution of volume fraction,pressure and velocity profiles describe the nature of the stratified wavy,stratified mixed and annular flow *** profiles help to developing the phenomenological correlations of interfacial characteristics in two-phase flow.

关键词： stratified Prediction pipe annular unsteady radial validated turbulent turbulence separated

Selenium Modulates Growth and Thiol Metabolism in Wheat (Triticum aestivumL.) during Arsenic Stress

在线全文

学校读者我要写书评

暂无评论

American Journal of Plant Sciences 2017年第3期8卷 363-389页

作者： Srijita Ghosh asok k. Biswas Plant Physiology and Biochemistry Laboratory Centre of Advanced Study Department of Botany University of CalcuttaKolkata India

Arsenic affects plants by disrupting their growth and metabolism while selenium, an essential micronutrient has beneficial role in stress tolerance. Owing to the antioxidative capacity of selenium, it can counteract detrimental effects of arsenic induced stress in plants. The interactive influence of arsenate and selenate on the growth, arsenic and selenium accumulation, activities of non-enzymatic and enzymatic antioxidants, levels of ascorbate, α-tocopherol, total glutathione and activities of glutathione regulatory enzymes along with characterization and quantification of phytochelatins in growing wheat (Triticum aestivum L.) seedlings were investigated. Rate of arsenic accumulation was increased in arsenate treated seedlings while in seedlings treated jointly with arsenate and selenate, arsenic accumulation decreased. Arsenate stress resulted decrease in ascorbate and total glutathione contents, activities of the glutathione metabolism enzymes while significantly increased the levels of α-tocopherol and phytochelatins (PC2 and PC4), along with activities of ascorbate peroxidase and ascorbic acid oxidase in the test seedlings. The effects were more pronounced in roots than in shoots. Joint application of arsenate along with selenate was able to overcome the adverse effects caused by arsenic alone to variable extents by exhibiting significant alterations of all parameters tested, imparting better growth and thiol metabolism in the test seedlings. Our results conclude that application of selenium fertilizer in arsenic contaminated soil might be favourable to improve growth and defense ability in wheat against arsenic toxicity.

关键词： Arsenate Glutathione Phytochelatins ROS Selenate

Regulation of Growth, Antioxidants and Sugar Metabolism in Rice (Oryza sativa L.) Seedlings by NaCl and Its Reversal by Silicon

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

American Journal of Plant Sciences 2016年第3期7卷 623-638页

作者： Prabal Das Paulin Seal asok k. Biswas Plant Physiology and Biochemistry Laboratory Centre of Advanced Study Department of Botany University of Calcutta Kolkata India

The effect of NaCl with or without silicon on the growth and metabolism in rice seedlings cv. MTU1010 was studied. In these seedlings, the oxidative stress has been observed with NaCl treatments and the levels of proline, H2O2 and malondialdehyde contents were increased whereas catalase activity was decreased. NaCl exposure at 25 mM, 50 mM and 100 mM concentrations in the test seedlings resulted in an increase in both reducing and non-reducing sugar content. There was a decrease in starch contents and the activity of starch phosphorylase was increased. NaCl stress also affected the activities of different carbohydrate metabolizing enzymes. The activities of sucrose synthase and sucrose phosphate synthase were increased, while the activity of acid invertase was decreased. Joint application of silicon with NaCl showed significant alterations on all parameters tested under the purview of NaCl treatment alone leading to better growth and metabolism in rice seedlings. Thus the use of silicon enriched fertilizers may help to grow healthy rice plants in NaCl rich soil.

关键词： Rice NaCl Silicon Antioxidant Sugar Metabolism

Funneling current in Si-doped infrared n type-GaAs heterostructures emitter

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Optoelectronics 2014年第4期7卷 501-508页

作者： Pradip DALAPATI Nabin Baran MANIk asok Nath BASU Condensed Matter Physics Research Center Department of Physics Jadavpur University Kolkata 700032 India

In the present work, we measured the forward bias current-voltage （I-V） characteristics of Si-doped n type gallium arsenide （GaAs） heterostructures infrared emitter over a wide temperature range from 350 to 77 k. Results showed that the slopes of the exponential curve changed slowly with temperature. The analysis of the various tunneling mechanisms indicated that the tunneling current varied approximately as a function of - exp（- αEg ＋ βeV） where the parameters α and β varied indistinctively with temperature and voltage tunneling current on the The dependence of forward temperature and bias can be explained by thermally induced band gap shrinkage and bias induced route change respectively. These results will be helpful for application of the optoelectronics device in both high and low temperature ambiences.

关键词： infrared emitter tunneling characteristic energy band gap thermal stress

Influence of Selenium on Growth, Antioxidants Production and Physiological Parameters of Rice (Oryza sativaL.) Seedlings and Its Possible Reversal by Coapplication of Sulphate

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

American Journal of Plant Sciences 2019年第12期10卷 2236-2278页

作者： Debarati Das Paulin Seal asok k. Biswas Plant Physiology and Biochemistry Laboratory Centre of Advanced Study Department of Botany University of Calcutta Kolkata India

The effect of selenate (Na2SeO4) and sulphate (Na2SO4) was studied on growth and metabolism in two rice cultivars cv. satabdi and cv. khitish. Selenate at low concentration (2 μM) expressed growth promoting effect on rice seedlings as opposed to its high concentration (≥20 μM) where the test seedlings showed stunted growth with browning at the apices of both roots and shoots. The chlorophyll contents showed a dose dependent effect. Both chlorophyll a and chlorophyll b contents were inhibited with increase in selenate concentrations. The effect was more pronounced in cv. satabdi compared to cv. *** level of accessory pigments was deferentially affected by selenium treatment. Simultaneously, the fluorescence intensity and Hill activity decreased with increase in selenate concentrations in the test seedlings. It is assumed that selenium plays a protective role in plants subjected to stress and prevents the formation of reactive oxygen species (ROS) in the cells. Higher selenate concentrations (≥20 μM) exerted variable effect on the activities of enzymatic antioxidants viz.;superoxide dismutase (SOD), catechol peroxidase (CPX) and catalase (CAT) in the test seedlings. The activity of SOD increased with increase in selenate concentrations, whereas activities of CAT and CPX decreased. Under high selenate concentrations, the levels of oxidative stress markers, viz.;proline, H2O2 and MDA were also enhanced. Selenium induced accumulation of total soluble sugar and increased the level of both reducing and non reducing sugars in both the test cultivars. The starch contents concomitantly decreased with rise in selenate concentrations. Moreover, the nutrient contents of test seedlings were significantly influenced by selenium. The Na and k levels gradually increased whereas Ca, Mg and Fe levels decreased on application of selenate. Joint application of 10 mM sulphate and selenate showed significant alterations on all parameters tested with respect to selenate treatment a

关键词： Rice Selenate Sulphate Growth Biochemical Changes

Versatile Potentiality of Silicon in Mitigation of Biotic and Abiotic Stresses in Plants: A Review

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

American Journal of Plant Sciences 2018年第7期9卷 1433-1454页

作者： Paulin Seal Prabal Das asok k. Biswas Plant Physiology and Biochemistry Laboratory Centre for Advanced Study Department of Botany University of Calcutta Kolkata India

The “quasi-essential element” silicon (Si) is not considered indispensable for plant growth and its accumulation varies between species largely due to differential uptake phenomena. Silicon uptake and distribution is a complex process involving the participation of three transporters (Lsi1, Lsi2 and Lsi6) and is beneficial during recovery from multiple stresses. This review focuses on the pivotal role of silicon in counteracting several biotic and abiotic stresses including nutrient imbalances, physical stresses together with uptake, transport of this metalloid in a wide variety of dicot and monocot species. The knowledge on the beneficial effects of silicon and possible Si-induced mechanisms of minimizing stress has been discussed. Accumulation of silicon beneath the cuticles fortifies the cell wall against pathogen attack. Si-induced reduction of heavy metal uptake, root-shoot translocation, chelation, complexation, upregulation of antioxidative defense responses and regulation of gene expression are the mechanisms involved in alleviation of heavy metal toxicity in plants. Silicon further improves growth and physiological attributes under salt and drought stress. Effective use of silicon in agronomy can be an alternative to the prevalent practice of traditional fertilizers for maintaining sustainable productivity. Therefore, soil nutrition with fertilizers containing plant-available silicon may be considered a cost-effective way to shield plant from various stresses, improve plant growth as well as yield and attain sustainable cultivation worldwide.

关键词： Abiotic Stress Alleviation Biotic Stress Silicon Silicon Transporter

Influence of Arsenate and Phosphate on the Regulation of Growth and TCA Cycle in the Rice (Oryza sativaL.) Cultivars IR64 and Nayanmani

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

American Journal of Plant Sciences 2017年第8期8卷 1868-1887页

作者： Jayeeta Saha Madhushree Dutta asok k. Biswas Plant Physiology and Biochemistry Laboratory Centre of Advanced Study Department of Botany University of Calcutta Kolkata India

The influence of arsenate and phosphate on the growth and respiration of 21 days old seedlings in two cultivars of rice, viz., IR64 and Nayanmani was studied. As arsenate and phosphate are similar in their chemical configuration and the latter is preferentially taken up by the phosphate transporters, it results in a competitive inhibition of arsenate uptake in presence of phosphate. Increasing concentrations of sodium arsenate (25 μM, 50 μM and 100 μM) hindered the growth in both the cultivars, with cv. IR64 being more severely affected than cv. Nayanmani. There was an elevation in the levels of organic acids measured in both the cultivars, accompanied by a reduction in the activities of the dehydrogenases of the TCA cycle, viz., pyruvate dehydrogenase, isocitrate dehydrogenase, succinate dehydrogenase and malate dedrogenase under arsenic treatment alone. Also, an elevation in the activities of citrate synthase and fumarase enzymes was noticed in both test seedlings with increasing concentrations of arsenic. These alterations were more prominent in cv. IR64 than in cv. Nayanmani. On joint application of phosphate along with arsenate, amelioration of the toxic effects of arsenate was observed to some extent, resulting in an overall revival of respiration leading to improved growth and metabolism.

关键词： Arsenic Phosphate Respiration Rice TCA cycle Amelioration