Wyniki wyszukiwania - Biblioteka Nauki

1

Enhancement in NBE emission and optical band gap by Al doping in nanocrystalline ZnO thin films

100%

Kumar N. , Srivastava A.

Opto-Electronics Review

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2018

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tom Vol. 26, No. 1

1--10

EN

Transparent Al doped ZnO nanocrystalline films with a crystallite size less than 19 nm are obtained by spray pyrolysis. Band gap increases monotonically from 3.16 to 3.31 eV with increasing aluminum dopant up to 1.56 at.% facilitating increasing width of a transmission window in addition to the band gap tuning of 4.74% which compares favorably well with literature. UV emission with continuously increasing intensity is obtained which reflects on the good crystalline quality of the films. Also the defect emissions are suppressed remarkably as the dopant Al concentration increases in ZnO. The band gap tuning by quite small increment in dopant amount makes the present films, much attractive for the fabrication of light emitting devices with a much sought-for benefit of large area fabrication. FESEM shows the surface is granular with grain size lying in the range of 20-35 nm and EDX confirms the presence of Al in the doped samples.

2

Some new results on information transmission over noisy channels

100%

Maheshwari S. , Srivastava A.

Demonstratio Mathematica

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2015

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tom Vol. 48, nr 3

462--472

EN

Information transmission over communication channels has been characterized by weighted information schemes involving probabilities and weights. Binary erasure channel has been used as an example for determination of constants in the proposed measure.

3

100%

Bansal P. , Srivastava A.

Acta Physiologiae Plantarum

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2017

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tom 39

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nr 07

4

In vitro response of black gram genotypes to herbicide stress and elevation of antioxidative defence system

100%

Bajpai J. , Srivastava A.

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tom 37

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nr 09

EN

In vitro response of seedlings of six genotypes of Vigna mungo L. Hepper to herbicide stress, induced by glyphosate was assessed by evaluating its effect on morphological parameters viz. germination percentage, survival percentage, shoot length, root length, fresh weight, as well as on biochemical parameters such as activity of antioxidative enzymes (catalase, peroxidase and superoxide dismutase), total protein and proline content along with MDA content. Findings indicate that herbicide treatment promotes significant and dose-dependent decrease in all morphological parameters and increase in activity of antioxidative enzymes in all the genotypes. Herbicide treatment promotes significant decrease in total protein content and increase in proline content. Significant variation for MDA content among genotypes was not observed. On the basis of results of present investigation, it was concluded that Vigna mungo genotypes tolerant to the herbicide stress can be of considerable practical value for studying the mechanism of herbicide tolerance and for providing genetic resources for the development of herbicide-tolerant cultivars.

5

Ground water in the City of Varanasi, India: present status and prospects

80%

Mohan K. , Srivastava A. , Rai P. K.

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tom 30

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nr 3

6

Simultaneous reverse-phase HPLC determination of major antioxidant phenolics in Commelina benghalensis L. tubers

80%

Misra A. , Srivastava A. , Srivastava S. , Rawat A. K. S.

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tom Vol. 28, no. 4

541--554

EN

Commelina benghalensis (Commelinaceae) is widely used as traditional and folklore medicine in India. In the present study, a reverse-phase high-performance liquid chromatography—photodiode array detection (RP-HPLC—PDA) method was developed for the separation, identification, and quantification of bioactive phenolics. Antioxidant potential was also accessed to validate the presence of identified markers. Method was developed on C18 column with 1% formic acid (in water) and acetonitrile as solvent system, and data acquisitions were achieved at wavelength of 285 nm. The developed method was also validated for accuracy, precision, robustness, limit of detection and quantification (LOD and LOQ), repeatability, and recovery according to International Conference on Harmonization (ICH) guidelines. In this method, five phenolics, viz., protocatechuic acid (0.033%), vanillic acid (0.262%), ferulic acid (0.365%), apigenin (0.126%), and kaempferol (0.544%), were quantified in linearity range of 0.2–1.0 μg with correlation coefficient of more than 0.9949. Relative standard deviation (RSD) (%), LOD, LOQ, and recovery (%) are within the acceptable limit. Besides that, methanolic extract shows the inhibition (%) range from 24.45 to 68.75% at 0.02–0.12 mg Ml-1. IC50 of extract was observed at 46.75 μg Ml-1, suggesting the promising activity in methanol extract. Hence, the proposed method for simultaneous quantification of five bioactive phenolics in the tuber of C. benghalensis using HPLC–PDA detection under the specified conditions is specific and accurate, and validation proves its selectivity and reproducibility.

7

Novel Coordination Complexes of the Trivalent Ruthenium, Rhodium and Iridium with Hydrazones Derived from Isatin Hydrazide and Various Aldehydes with Spectral and Biological Characterization

80%

Sharma V. , Srivastava S. , Srivastava A.

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2006

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tom Vol. 80, nr 3

387-396

EN

Aseries of several new ruthenium(III), rhodium(III) and iridium(III) complexes with hydrazones of general formula [M(LH)3]Cl3 were synthesized in order to meet requirements essential for biological properties. Hydrazones were formed by isatin hydrazide and various aldehydes namely anisaldehyde, benzaldehyde, o-chlorobenzaldehyde, p-chlorobenzaldehyde and p-fluorobenzaldehyde. Physicochemical characterization of compounds has been carried out by elemental analyses, spectroscopic (IR, electronic, 1H NMR), thermogravimetric and magnetic studies. These complexes show higher conductance values, supporting their electrolytic nature. All the studies revealed octahedral nature of the complexes with nitrogen and oxygen of azomethine and carbonyl group as binding sites and exhibited monomeric nature of the complexes. Rhodium(III) and iridium( III) complexes were found diamagnetic and show intense absorptions while ruthenium( III) complexes show paramagnetic behaviour. In addition, antifungal and antibacterial studies have been carried out in vitro for investigated compounds against fungus A. niger and F. oxysporium and bacteria E. coli and S. aureus. Most of the metal chelates show higher biocidal activity for the above microorganisms than that of the free ligand.

8

Investigating the role of air-sea forcing on the variability of hydrography, circulation, and mixed layer depth in the Arabian Sea and Bay of Bengal

80%

Srivastava A. , Dwivedi S. , Mishra A. K.

Oceanologia

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2018

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tom No. 60 (2)

169--186

EN

An effort is made to understand and quantify the influence of near surface zonal and meridional winds, incoming shortwave radiation, and freshwater flux air-sea forcings on the seasonal variability of the hydrography, circulation, and mixed layer depth of the Arabian Sea (AS) and Bay of Bengal (BoB). Sensitivity experiments using an ocean general circulation model are carried out for this purpose in the Indian ocean around 65°-95°E, 5°-22°N during 1998-2014 (17 years). In the absence of near surface wind forcing, the sea surface temperature of the region greatly increases in all the seasons, whereas, in the absence of incoming shortwave radiation forcing, exactly opposite is the case. The sea surface salinity of the AS and BoB decreases in the absence of wind and shortwave radiation forcings, whereas, in the northern BoB it increases in the absence of freshwater flux forcing. The sub-surface changes in the stratification of temperature and salinity are also investigated. The influence of the air-sea forcings on the mixed layer depth of the region is found to be highly seasonally dependent. The effect of air-sea forcings on the seasonal variability of the upper ocean vertical stability is studied using the vertical shear of the horizontal velocity, buoyancy frequency, and energy required for mixing as quantifiers. The near surface wind forcing has highest contribution in changing the surface circulation of the region.

9

Investigating the role of air-sea forcing on the variability of hydrography, circulation, and mixed layer depth in the Arabian Sea and Bay of Bengal

80%

Srivastava A. , Dwivedi S. , Mishra A. K.

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tom 60

|

nr 2

10

Dissipation of nitrapyrin (nitrification inhibitor) in subtropical soils

80%

Rakhi , Srivastava A. , Srivastava P. C.

Polish Journal of Soil Science

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2019

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tom 52

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nr 2

EN

Nitrapyrin (2-chloro-6-(trichloromethyl)pyridine) is a specific nitrification inhibitor, applied in soils for reducing the nitrification process of nitrogenous fertilizers. The overall effect of nitrapyrin is enhancing the efficiency of nitrogenous fertilizers in soils and also controlling environmental pollution in water by preventing nitrate leaching in soils. Dissipation of nitrapyrin was evaluated in subtropical soils at two fortification levels of 2 and 4 µg·g⁻¹. The extraction of nitrapyrin was done by quick, easy, cheap, rugged and safe (QuEChERS) method and quantitative analysis – by high-performance liquid chromatography (HPLC). Nitrapyrin residues declined consistently with time in both types of soils and were not detectable (<0.05 µg·g⁻¹) on the 45th day at 2 µg·g⁻¹ and on the 60th day at 4 µg·g⁻¹ application rate. Dissipation of nitrapyrin occurred in a single phase with the persistence data fitting well to the first-order kinetics. The half-life of nitrapyrin was 9.6 and 9.9 d at 2 µg·g⁻¹ and 16.1 d and 17.3 d at 4 µg·g⁻¹ application rate in both types of soils. The results revealed higher persistence of nitrapyrin at higher concentration (4 µg·g⁻¹) in both types of soils, probably because of high temperature and humidity in subtropical soils.

11

Optical and sensing properties of Fe doped ZnO nanocrystalline thin films

71%

Shukla R. K. , Srivastava A. , Kumar N. , Pandey A. , Pandey M.

Materials Science Poland

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2016

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tom Vol. 34, No. 2

354--361

EN

Undoped and Fe doped ZnO films of different molarities deposited by spray pyrolysis method using zinc nitrate and ferric chloride as precursors show polycrystalline nature and hexagonal wurtzite structure. Crystallite size decreases with an increase in dopant concentration from 0 at.% to 3 at.%. Doping improves the transmission of the films whereas it reduces the optical band gap of ZnO from 3.28 eV to 3.17 eV. The morphology resembles flake-like structures which collapse when the dopant is introduced. The samples are found to be sensitive to CO2 gas. Undoped ZnO shows maximum sensitivity at 350 ºC for higher concentration of CO2. Doped samples show maximum sensitivity at 200 ºC for all CO2 concentrations i.e. from 500 ppm to 4000 ppm. Maximum sensitivity is achieved at temperatures 350 ºC, 250 ºC, 300 ºC and 450 ºC for the samples prepared using precursor solution of 0.1 M molarity.

12

Rapid transport of protons across membranes

70%

Krishnamoorthy G. , Ahmed I. , Singh S. , Maity H. P. , Srivastava A.

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1994

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tom 12

|

nr 1

13

Growth promotion and charcoal rot management in chickpea by Trichoderma harzianum

61%

Jyotsna , Srivastava A. , Singh R. P. , Srivastava A. K. , Saxena A. K. , Arora D. K.

Journal of Plant Protection Research

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2008

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tom 48

|

nr 1

81-92

EN

The strains of Trichoderma harzianum were assessed for their effect on chickpea growth and control of charcoal rot caused by Macrophomina phaseolina in greenhouse assay. T. harzianum strain 25-92 significantly increased the fresh and dry weights by 50-63% and 24-42%, respectively, whereas strain 29-92 increased the fresh weight of chickpea cv. Radhey and Vishwas by 12-30% but not the dry weight in the absence of M. phaseolina. A marked increase in root length was caused by both the strains. In M. phaseolina infested pots, number of lateral roots and branching decreased with nonsignificant change in weight. Significant (P = 0.05) reduction in charcoal rot disease was observed in the pots amended with T. harzianum at all the concentrations. Moreover, 60-40% reduction in disease was recorded after 14 and 28 days in chickpea varieties Radhey and Vishwas. The resistant variety Vijay does not show significant disease. The reduction in disease was more pronounced at higher inoculum concentrations of T. harzianum (107-108 cfu/g). Overall, Trichoderma strain 25-92 improved plant growth and reduced damage in presence of the pathogen. Besides disease control the growth promoting properties of the strain improve the efficacy for commercial application.

PL

Testowano w warunkach szklarniowych działanie szczepów Trichoderma harzianum na wzrost ciecierzycy pospolitej (Cicer arietinum) i na czernienie Roślin wywoływane przez Macrophomia phaseolina. Pod nieobecność M. phaseolina szczep 25-92 T. harzianum powodowałistotne zwiększenie świeżej i suchej masy Roślin odpowiednio o 50-63% i 24-42%, podczas gdy szczep T. harzianum 29-92 wpływał na zwiększenie świeżej masy, lecz nie suchej masy odmian ciecierzycy Radhey i Vishwas o 12-30%. Badane szczepy T. harzianum powodowały znaczne zwiększenie długości korzeni. W wazonach zakażonych grzybem M. phaseolina zarówno ilość jak i długość bocznych korzeni i rozgałęzianie się ich spadło, co jednak nie wywoływało istotnych zmian masy Roślin. Istotne (P = 0,05) ograniczenie choroby zaobserwowano w wazonach z dodatkiem T. harzianum w różnych koncentracjach, a ograniczenie choroby na odmianach Radhey i Vishwas o 60-40% odnotowano odpowiednio po 14 i 28 dniach. Odporna odmiana Vijay nie wykazuje istotnego porażenia przez M. phaseolina. Ograniczenie występowania choroby było wyraźniejsze przy wyższych stężeniach inokulum T. harzianum (107-108 cfu/g). W podsumowaniu można stwierdzić, że szczep T. harzianum 25-92 wpływał na polepszenie wzrostu Roślin i ograniczał szkody w obecności patogena M. phaseolina. Ograniczenie występowania choroby i działanie stymulujące wzrost Roślin ma znaczenie w odniesieniu do zastosowania grzyba antagonistycznego T. harzianum w warunkach produkcyjnych.

14

Analysis of birefringence property of three different nematic liquid crystals dispersed with TiO₂ nanoparticles

61%

Pathak G. , Katiyar R. , Agrahari K. , Srivastava A. , Dabrowski R. , Garbat K. , Manohar R.

Opto-Electronics Review

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2018

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tom Vol. 26, No. 1

11--18

EN

In the present work TiO₂ nanoparticles (NPs) have been dispersed into three different nematic liquid crystals (2020, 1823A and 1550C) in different concentration. The value of the birefringence (Δn) has been calculated by the transmitted intensity method at a 632.8 nm wavelength. NLC 2020 used in the present study is a high birefringent material (Δn = 0.44), NLC 1550C is a low birefringent material (Δn = 0.067) and NLC 1823A is a mid birefringent material (Δn = 0.14). An increased value of birefringence has been found after dispersion of TiO₂ NPs in all three NLCs but this increment depends upon the concentration of the dopant material, temperature range and chemical character of the mixtures. It is suggested that this LC materials can be applicable in making of phase shifters, compensators and many more photonic devices.

15

Mitigation of As toxicity in wheat by exogenous application of hydroxamate siderophore of Aspergillus origin

61%

Kumari S. , Khan A. , Singh P. , Dwivedi S. K. , Ojha K. K. , Srivastava A.

Acta Physiologiae Plantarum

|

2019

|

tom 41

|

nr 07

EN

Siderophores are secondary metabolites having molecular weight less than 10 KD. They are specifically meant for chelation of ferric ions. They also tend to chelate metals under heavy metal stress, thus reducing their toxic effects. In the current study, experiments have been conducted on wheat plants to analyse siderophore’s ability to counteract the adverse impact of arsenic (As) toxicity on physiology of plant seedlings along with biochemical response. As toxicity has been observed to adversely affect the lengths of root and shoot, chlorophyll and carotenoid contents, and activities of various antioxidative enzymes. The present study revealed that the application of hydroxamate-type siderophore isolated from Aspergillus nidulans under toxic condition significantly recovered the growth and helped in amending the enzymatic activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) of wheat genotype (NW1014). At the same time, injury caused by lipid peroxidation was significantly reduced. In silico studies revealed better binding affinity of ferricrocin–arsenate complex leading to thermodynamically stable complex. Encouraging results of As containment by organic biomolecule-siderophore can lead to an emerging bioremediation mechanism brimming with opportunities for agricultural field and environmental clean-up.

16

Microarray Inspector: tissue cross contamination detection tool for microarray data

51%

Stepniak P. , Maycock M. , Wojdan K. , Markowska M. , Perun S. , Srivastava A. , Wyrwicz L. S. , Swirski K.

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2013

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tom 60

|

nr 4

EN

Microarray technology changed the landscape of contemporary life sciences by providing vast amounts of expression data. Researchers are building up repositories of experiment results with various conditions and samples which serve the scientific community as a precious resource. Ensuring that the sample is of high quality is of utmost importance to this effort. The task is complicated by the fact that in many cases datasets lack information concerning pre-experimental quality assessment. Transcription profiling of tissue samples may be invalidated by an error caused by heterogeneity of the material. The risk of tissue cross contamination is especially high in oncological studies, where it is often difficult to extract the sample. Therefore, there is a need of developing a method detecting tissue contamination in a post-experimental phase. We propose Microarray Inspector: customizable, user-friendly software that enables easy detection of samples containing mixed tissue types. The advantage of the tool is that it uses raw expression data files and analyses each array independently. In addition, the system allows the user to adjust the criteria of the analysis to conform to individual needs and research requirements. The final output of the program contains comfortable to read reports about tissue contamination assessment with detailed information about the test parameters and results. Microarray Inspector provides a list of contaminant biomarkers needed in the analysis of adipose tissue contamination. Using real data (datasets from public repositories) and our tool, we confirmed high specificity of the software in detecting contamination. The results indicated the presence of adipose tissue admixture in a range from approximately 4% to 13% in several tested surgical samples.