Wyniki wyszukiwania - Biblioteka Nauki

1

Electronic and structural properties of rare earth pnictides

100%

Bhardwaj R.

Materials Science Poland

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2016

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tom Vol. 34, No. 1

45--52

EN

In the present paper structural and electronic properties of rare earth pnictides have been presented. The present calculation has been performed using self-consistent tight binding linear muffin tin orbital (TB-LMTO) method within the local density approximation (LDA). The studied compounds undergo a structural phase transition from NaCl-type structure to CsCl-type structure. The electronic band structure and density of states of the pnictides have been reported. The equilibrium lattice parameter a (A), bulk modulus B (GPa), number of f-states at the Fermi level Nf (states/Ry cell) and volume collapse of AmBi and CmBi have also been reported. The calculated equilibrium structural parameters are in good agreement with the available experimental results.

2

Aerodynamic Torque exhibits non-resonance oscillation in satellite motion

63%

Bhardwaj R. , Kaur M.

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2016

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tom Vol. 44, No. 2

247--261

EN

This paper deals with the non-linear oscillation of a satellite in an elliptic orbit around the Earth under the influence of aerodynamic and gravitational torque. It is assumed that the orbital plane coincides with the equatorial plane of the Earth. Using Bogoliubov–Krylov–Mitropolsky (BKM) methods of nonlinear oscillations, it is observed that the amplitude of the oscillation remains constant up to the second order of approximation. Numerically time series, 2D and 3D phase spaces are plotted for Earth Moon system using Matlab. The existence of main and parametric resonance concludes the different frequency states which transit the motion from regular to an attractor that leads to chaotic state.

PL

Artykuł poświęcony jest nieliniowej oscylacji satelity w eliptycznej orbicie wokół Ziemi pod wpływem grawitacji i aerodynamicznego momentu obrotowego. Przyjmuje się, że płaszczyzna orbity pokrywa się z płaszczyzną równikową Ziemi. Po zastosowaniu metody nieliniowych oscylacji Bogoliubova–Krylova–Mitropolsky’ego (BKM) obserwujemy, że amplituda oscylacji jest stała przy aproksymacji rzędu drugiego. Ilustracje szeregów czasowych w przestrzeni fazowej 2- i 3-wymiarowej wykonano z wykorzystaniem procedur zaimplementowanych w MatLabie. Istnienie głównej składowej rezonansu i składowych parametrycznych wyjaśnia chaotyczny charakter częstotliwości.

3

Effects of 24-epibrassinolide on growth and metal uptake in Brassica juncea L. under copper metal stress

63%

Sharma P. , Bhardwaj R.

Acta Physiologiae Plantarum

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2007

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tom 29

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nr 3

EN

The present investigation describes the effects of 24-epibrassinolide on plant growth, copper uptake and bioconcentration factor in the plants of Brassica junceaL. cv. PBR 91 under Cu metal stress. The study revealed that there was an improvement in the shoot emergence and plant biomass production under the influence of pre-germination treatment of 24-epibrassinolide (24-epiBL). In addition, 24-epiBL blocked copper metal uptake and accumulation in the plants.

4

Effect of 24-epibrassinolide on oxidative stress markers induced by nickel-ion in Raphanus sativus L.

51%

Sharma I. , Pati P. K. , Bhardwaj R.

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nr 5

EN

The present study illustrates the effect of 24-epibrassinolide (24-EBL) on morphological and biochemical parameters in radish (Raphanus sativus L.) seedlings grown under nickel (Ni) ion stress. The radish seeds pre-soaked in different concentrations of 24-EBL were sown in petridishes containing various concentrations of heavy metal (Ni).Observations were made on root/shoot length, fresh biomass, activities of antioxidant enzymes (ascorbate peroxidase, superoxide dismutase, catalase, monodehydroascorbate reductase, dehydroascorbate reductase, guaiacol peroxidase and glutathione reductase), lipid peroxidation, proline and protein content in 7-day-old Ni-stressed radish seedlings. Results indicate that seeds presoaked with 24-EBL reduced the impact of Ni-stress which was evident by assessing the morphological parameters, protein content and antioxidant enzyme activities. It was also observed that 24-EBL reduced the toxicity of heavy metal by influencing proline and malondialdehyde (MDA) content. The present study lays a foundation for understanding the role of 24-EBL in heavy metal stress amelioration, particularly in food crop. Analysis of behaviour of antioxidant enzymes will play a critical role in understanding the stress networking, further filling the knowledge gap on the subject.

5

Effect of 24-epibrassinolide on growth, protein content and antioxidative defense system of Brassica juncea L. subjected to cobalt ion toxicity

51%

Arora P. , Bhardwaj R. , Kanwar M. K.

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2012

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tom 34

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nr 5

EN

Brassica juncea L. plants were subjected to cobalt (Co) ion (0, 5 × 10⁻⁴, 10⁻³, 1.5 × 10⁻³ and 2 × 10⁻³ M) toxicity and were sprayed with different concentrations of 24-epibrassinolide (24-EBL) (0, 10⁻¹⁰, 10⁻⁸ and 10⁻⁶ M) at 15-day stage after sowing. They were sampled at 30 and 60 days after sowing and analyzed for growth parameters in terms of shoot length and number of leaves. Thereafter, leaves were excised and content of proteins and the activities of antioxidative enzymes (superoxide dismutase (SOD) (EC 1.15.1.1) catalase (CAT) (EC 1.11.1.6), ascorbate peroxidase (APOX) (EC 1.11.1.11), guaiacol peroxidase (POD) (EC 1.11.1.7) glutathione reductase (GR) (EC 1.6.4.2), monodehydroascorbate reductase (MDHAR) (EC 1.1.5.4) and dehydroascorbate reductase (DHAR) (EC 1.8.5.1)) were analyzed. The plants exposed to cobalt ion exhibited a significant decline in growth in terms of shoot length and number of leaves. However, foliar spray treatment with 24-EBL was able to alleviate the stress generated by cobalt ion and significantly improved the above parameters. The activities of antioxidative enzymes (SOD, CAT, POD, GR, APOX,MDHAR and DHAR) and protein content were also regulated considerably in leaves of plants treated with 24-EBL alone, 10⁻⁸ M concentration being the most effective. The activities of antioxidative enzymes also increased in leaves of B. juncea plants by the application of cobalt ion to soil and consequently sprayed with 24-EBL. Similarly, the protein content was also regulated in leaves of B. juncea plants treated with 24-EBL as compared to untreated control plants, thereby revealing stress-protective properties of 24-EBL.

6

24-epibrassinolide restores the synthesis of proteins and amino acids in Brassica juncea L. leaves under imidacloprid stress

51%

Sharma A. , Kumar V. , Kumar Thukral A. , Bhardwaj R.

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2017

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tom 25

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nr 2

7

Multivariate analysis on the distribution of elements in plants

45%

Kumar V. , Sharma A. , Bakshi P. , Bhardwaj R. , Thukral A. K.

Acta Physiologiae Plantarum

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2018

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tom 40

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nr 11

8

Role of Se(VI) in counteracting oxidative damage in Brassica juncea L. under Cr(VI) stress

45%

Handa N. , Kobli S. K. , Thukral A. K. , Arora S. , Bhardwaj R.

Acta Physiologiae Plantarum

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2017

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tom 39

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nr 02

9

Isolation and characterization of 24-Epibrassinolide from Brassica juncea L. and its effects on growth, Ni ion uptake, antioxidant defense of Brassica plants and in vitro cytotoxicity

38%

Kumar Kanwar M. , Bhardwaj R. , Chowdhary S. P. , Arora P. , Sharma P. , Kumar S.

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nr 04

EN

Brassinosteroids (BRs) are a group of steroidal plant hormones which are essential for growth and development of plants. These hormones affect plant growth and development through a spectrum of physiological responses. Recent reports showed their stress-protective, antiviral, antitumor and antigenotoxic potential. In the present study, an attempt was made to isolate 24-Epibrassinolide from 30-days-old Brassica juncea L. plants which was characterized by ESI–MS analysis. The ESI–MS analysis of isolated Brassinolide was compared with the standard 24-Epibrassinolide, which confirmed its MS/MS fragmentation pattern. Various concentrations of the isolated brassinosteroid were given as pre-sowing treatment to the seeds of B. juncea for 8 h. The pre-treated seeds were then raised in experimental pots containing different concentrations of nickel ion. After 30 days, plants were harvested and analyzed for growth parameters, ion uptake and antioxidant defense system. It was observed that pre-treatment of isolated 24-Epibrassinolide lowered the Ni ion uptake in plants and improved growth. The amelioration of Ni toxicity was also observed by the activities of antioxidant enzymes. The in vitro cytotoxicity of natural 24-Epibrassinolide against different cancer cell lines was checked by employing sulphorhodamine bioassay and it revealed significant inhibition in the lung cancer cell line.

10

Enhancing effects of 24-epibrassinolide and Putrescine on the antioxidant capacity and free radical scavenging activity of Raphanus sativus seedlings under Cu ion stress

38%

Choudhary S. P. , Bhardwaj R. , Gupta B. D. , Dutt P. , Gupta R. K. , Kanwar M. , Biondi S.

Acta Physiologiae Plantarum

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2011

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tom 33

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nr 4

EN

The present investigation recorded significant restoration of seedling growth (root length, shoot length and fresh weight) upon application of 24-epibrassinolide (EBL) and putrescine (Put) to 7-day-old seedlings of Raphanus sativus L. cv. Pusa chetki grown under copper (Cu) ion stress. EBL and Put with/or without Cu ion treated seedlings showed increased titers of ascorbic acid, total phenols and proline when compared with Cu-stressed seedlings. Differential responses in the activities of guaiacol peroxidase (GPOX) and catalase (CAT) were noted for EBL and Put alone or with/or without Cu ion treatment. Decreased activities of glutathione reductase (GR) and superoxide dismutase (SOD) noted for EBL and Put alone were observed to enhance significantly when applied in combination with Cu ion solution. A remarkable decrease in malondialdehyde contents was observed in seedlings treated with EBL and Put alone and with/or without Cu ion stress. Enhanced free radical scavenging activities were also recorded for seedlings given EBL and Put alone or in combination over Cu ion stressed seedlings. Maximum DPPH activity was observed in seedlings treated with Put and EBL 10⁻⁹ M + Put. Significant enhancements in deoxyribose and reducing power activities were too recorded for Put, EBL and Put + 10⁻⁹ M EBL treatments. Improved seedling growth, antioxidant levels (ascorbic acid, total phenols and proline) and enzymic (GPOX, CAT, SOD and GR) activities and free radical scavenging capacities along with reduced membrane damage in seedlings given EBL and Put with/or without Cu stress suggests significant and positive interactions of EBL and Put in alleviating the Cu ion induced oxidative damage in radish seedlings.