http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Nirpendra Singh (검색결과 4 건)
- 무료
- 기관 내 무료
- 유료
-
Electronic Structures and Optical Properties of Spinel ZnCr2O4
Nirpendra Singh,이주열 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.5
The electronic structures and optical properties of zinc chromite, ZnCr2O4, were calculated using the density-functional theory within the local-spin-density approximation (LSDA), the LSDA plus Hubbard-like parameter U, LSDA+U, and the spin-polarized generalized-gradient approximation. ZnCr2O4 was found to be a direct-band-gap semiconductor with an optical band gap of 2.9 eV, with the uppermost valence bands (lowermost conduction bands) having mainly Cr-t2g (Cr-e<SUB>g</SUB>) characteristics. The calculated band gap using LSDA+U showed better agreement with the available experimental data than previous calculations. The optical-conductivity and the reflectivity spectra were also calculated. The calculated reflectivity spectrum exhibited two peaks, one at ~3.5 eV and the other at ~5.8 eV, which were assigned to the electronic interband transitions from the O-2p to the Cr-3d states and from the O-2p derived bands to the Cr eg bands, respectively.
-
Large Low-energy Oscillator Strength for Eu 4f Electrons of a Rare-earth Zintl Compound: EuIn_2P_2
Nirpendra Singh,이주열 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.3
A newly found Zintl compound EuIn_2P_2 has been investigated within the density-functional theory, and results of a detailed investigation of its electronic structure and related properties are reported. We employed the so-called LSDA+U method (LSDA: local-spin-density approximation) with varying U from 0 eV to 7 eV to take into account the strong on-site Coulomb repulsion between the Eu 4f -electrons and to reproduce the semiconducting energy gap of 3.2 meV experimentally observed by J. Jiang and S. M. Kauzlarich [Chem. Mater. 18, 435 (2006)]. The calculations, however, could not reproduce the energy gap even for the largest U value of 7.0 eV because the experimental gap was not an optical gap, but it was deduced from the temperature dependence of resistivity at 26 − 60 K; thus, the experimental gap was not a real ‘semiconducting’ gap. The calculated optical-conductivity spectrum with U = 7.0 eV could not reproduce the experimental spectrum, while with simple LSDA, the calculated spectrum resembled the experimental one rather successfully. Therefore, it seems that the LSDA+U method is not suitable to correctly simulate the optical properties of this compound. Contrary to the expectation, we found that EuIn_2P_2 had a large oscillator strengths for f ! d transitions in the low-energy range (below 1.5 eV); i.e., the peaks located at ∼0.6 eV and ∼1.1 eV in the experimental spectrum are mainly due to transitions from f -bands to d-bands, in which joint density-of-states effects play a key role. We also found that the magneto-optical Kerr effect was quite large in the EuIn_2P_2 compound.
-
이주열,Nirpendra Singh,S. Auluck 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2
Orthorhombic rare-earth orthoferrites are studied using density-functional theory. The electronic, optical and magneto-optical properties are investigated in both ferromagnetic (FM) and anti-ferromagnetic (AFM) phases. Our calculations show that the antiferromagnetic phase is energetically favorable. The calculated complex Kerr rotation of YFeO3 is in good agreement with the experimental data. Our calculations yield a value of the magneto-optical Kerr angle between -0.4 to 0.4 degrees. To see the resemblance between the complex Kerr rotation and complex optical conductivity, we also have calculated the diagonal and the off-diagonal components of the optical-conductivity tensor.
-
( Kumar Pranaw ),( Surender Singh ),( Debjani Dutta ),( Nirpendra Singh ),( Garima Sharma ),( Sudershan Ganguly ),( Vinay Kalia ),( Lata Nain ) 한국미생물 · 생명공학회 2013 Journal of microbiology and biotechnology Vol.23 No.11
Proteases produced by Xenorhabdus are known to play a significant role in virulence leading to insect mortality. The present study was undertaken to purify and characterize protease from Xenorhabdus indica, an endosymbiont of nematode Steinernema thermophilum, and to decipher its role in insect mortality and its efficacy to control Helicoverpa armigera. A set of 10 strains of Xenorhabdus isolated from different regions of India were screened for protease activity on the basis of zone of clearing on gelatin agar plates. One potent strain of Xenorhabdus indica was selected for the production of protease, and the highest production (1,552 U/ml) was observed at 15-18 h of incubation at 28oC in soya casein digest broth. The extracellular protease was purified from culture supernatant using ammonium sulfate precipitation and ion-exchange chromatography. The enzyme was further characterized by SDS-PAGE and zymography, which confirmed the purity of the protein and its molecular mass was found to be ~52 kDa. Further MALDI-TOF/TOF analysis and effect of metal chelating agent 1,10-phenanthrolin study revealed the nature of the purified protease as a secreted alkaline metalloprotease. The bioefficacy of the purified protease was also tested against cotton bollworm (Helicoverpa armigera) and resulted in 67.9 ± 0.64% mortality within one week. This purified protease has the potential to be developed as a natural insecticidal agent against a broad range of agriculturally important insects.
KISS연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
