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1.
Tetra- and pentapeptides of α-methylalanine give with PCl5, SOCl2 etc. intermediates which, with or without loss of amino adds, lead to bi- and tricyclic products containing imidazole and piperazine rings through different routes. 相似文献
2.
Triton-emission cross sections were measured for Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo, Ag, Ta, Tl, Pb and Bi with a 30 MeV d(Be) break-up neutron spectrum characterized by a multiple-foil activation technique. The accumulated tritium was separated by vacuum extraction and measured by low-level gas-phase β? counting. The systematic trend in the cross sections is somewhat similar to that in the 53 MeV d(Be) break-up neutron spectrum; apart from some initial decrease as a function of Z, the cross section is almost constant over the entire range of Z = 22 to 83. The magnitudes of the cross sections lie between those with 14 MeV neutrons and 53 MeV d(Be) break-up neutrons. Hauser-Feshbach calculations show that the statistical model describes the triton-emission cross sections for nuclei in the (2s, ld) shell within a factor of 2; for the heavier nuclei, however, the calculated cross sections are much smaller than the experimental values. 相似文献
3.
Mohammad Bodiuzzaman Atanu Ghosh Korath Shivan Sugi Abhijit Nag Esma Khatun Babu Varghese Ganesan Paramasivam Sudhadevi Antharjanam Ganapati Natarajan Thalappil Pradeep 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(1):195-200
Two ligand‐protected nanoscale silver moieties, [Ag46(SPhMe2)24(PPh3)8](NO3)2 and [Ag40(SPhMe2)24(PPh3)8](NO3)2 (abbreviated as Ag46 and Ag40, respectively) with almost the same shell but different cores were synthesized simultaneously. As their external structures are identical, the clusters were not distinguishable and become co‐crystallized. The occupancy of each cluster was 50 %. The outer shell of both is composed of Ag32S24P8, which is reminiscent of fullerenes, and it encapsulates a well‐studied core, Ag14 and a completely new core, Ag8, which correspond to a face‐centered cube and a simple cube, respectively, resulting in the Ag46 and Ag40 clusters. The presence of two entities (Ag40 and Ag46 clusters) in a single crystal and their molecular formulae were confirmed by detailed electrospray ionization mass spectrometry. The optical spectrum of the mixture showed unique features which were in good agreement with the results from time‐dependent density functional theory (TD‐DFT). 相似文献
4.
Tris(pentafluorophenyl)borane [B(C6F5)3] has been used as an efficient catalyst for reductive alkylation of alkoxy benzenes using aldehydes as an alkylating agent in the presence of polymethylhydrosiloxane (PMHS). Various alkylated trimethoxybenzene derivatives have been prepared in good to high yields. In addition, B(C6F5)3 was also used as a catalyst for the reaction of electron-rich arenes with aldehydes to obtain triarylmethanes. The use of reductive alkylation protocol for the synthesis of an isochroman and tetrahydroisoquinoline derivatives has also been demonstrated. 相似文献
5.
Tajkera Khatun Tapati Dutta Sujata Tarafdar 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(11):213
We describe the Island-Mainland (IM) transition on a square lattice. Black squares are randomly dropped on a white background, with increasing concentration p. We define black (white) clusters as groups of black (white) squares, connected through edges or corners on a quasi-2D system. At a certain p the black islands in white sea (IS) phase crosses over to a mixed phase (MP). At still larger p the MP phase crosses over to the lakes in mainland (LM) phase with white lakes in a black mainland. We show that the Euler number, defined as difference between number of white clusters and number of black clusters goes through extrema near these transition points. The phenomenon is supported by experimental observations. 相似文献
6.
Anil Kumar Sudeep SharanNitin Kumar Udaybir SinghH. Khatun V. VyasA.K. Sinha 《Infrared Physics & Technology》2012,55(1):93-97
This paper describes the design of a large sized diamond window for 1 MW, 170 GHz gyrotron. The diameter and the thickness of the diamond window are 80 mm and 1.482 mm, respectively, whose edge is directly cooled by water. The CST microwave studio has been used for the S-parameter, and finite element analysis code ANSYS has been used for the thermal and the structural simulation. The return loss (S11) and insertion loss (S21) of the 170 GHz gyrotron window have been found −39.80 dB and −0.011 dB, respectively. The thermal and structural analysis of RF window the 397 K temperature at disk center and maximum displacement 0.01 mm has been found in the window disk during the thermal analysis. 相似文献
7.
Soo Yeon Kim Arup Podder Hyunseung Lee Youn-Joo Cho Eun Hee Han Sabina Khatun Jonathan L. Sessler Kwan Soo Hong Sankarprasad Bhuniya 《Chemical science》2020,11(36):9875
Abnormal anaerobic metabolism leads to a lowering of the pH of many tumours, both within specific intracellular organelles and in the surrounding extracellular regions. Information relating to pH-fluctuations in cells and tissues could aid in the identification of neoplastic lesions and in understanding the determinants of carcinogenesis. Here we report an amphiphilic fluorescent pH probe (CS-1) that, as a result of its temporal motion, provides pH-related information in cancer cell membranes and selected intracellular organelles without the need for specific tumour targeting. Time-dependent cell imaging studies reveal that CS-1 localizes within the cancer cell-membrane about 20 min post-incubation. This is followed by migration to the lysosomes at 30 min before being taken up in the mitochondria after about 60 min. Probe CS-1 can selectively label cancer cells and 3D cancer spheroids and be readily observed using the green fluorescence channel (λem = 532 nm). In contrast, CS-1 only labels normal cells marginally, with relatively low Pearson''s correlation coefficients being found when co-incubated with standard intracellular organelle probes. Both in vivo and ex vivo experiments provide support for the suggestion that CS-1 acts as a fluorescent label for the periphery of tumours, an effect ascribed to proton-induced aggregation. A much lower response is seen for muscle and liver. Based on the present results, we propose that sensors such as CS-1 may have a role to play in the clinical and pathological detection of tumour tissues or serve as guiding aids for surgery.A self-assembled amphiphilic fluorescent probe allows pH-fluctuations within cancer cells and tumour tissues to be readily detected. 相似文献
8.
Atikur Rahman M. Akter M. R. Khatun M. Romana Sultana R. Sarker M. A. Razzaque 《Physics of the Solid State》2020,62(6):1024-1032
Physics of the Solid State - Employing the solid-state reaction route, good quality polycrystalline sample NiV2O6 is prepared that has effective application in rechargeable Li-ion batteries. The... 相似文献
9.
Journal of Thermal Analysis and Calorimetry - Colchicine (Col), a naturally occurring alkaloid, has been used as an anti-inflammatory, anti-fibrotic, and anti-tumor drug. The present study reports... 相似文献
10.
The ternary arsenides A(2)Zn(2)As(3) and the quaternary derivatives A(2)Ag(2)ZnAs(3) (A = Sr, Eu) have been prepared by stoichiometric reaction of the elements at 800 °C. Compounds A(2)Zn(2)As(3) crystallize with the monoclinic Ba(2)Cd(2)Sb(3)-type structure (Pearson symbol mC28, space group C2/m, Z = 4; a = 16.212(5) ?, b = 4.275(1) ?, c = 11.955(3) ?, β = 126.271(3)° for Sr(2)Zn(2)As(3); a = 16.032(4) ?, b = 4.255(1) ?, c = 11.871(3) ?, β = 126.525(3)° for Eu(2)Zn(2)As(3)) in which CaAl(2)Si(2)-type fragments, built up of edge-sharing Zn-centered tetrahedra, are interconnected by homoatomic As-As bonds to form anionic slabs [Zn(2)As(3)](4-) separated by A(2+) cations. Compounds A(2)Ag(2)ZnAs(3) crystallize with the monoclinic Yb(2)Zn(3)Ge(3)-type structure (Pearson symbol mC32, space group C2/m; a = 16.759(2) ?, b = 4.4689(5) ?, c = 12.202(1) ?, β = 127.058(1)° for Sr(2)Ag(2)ZnAs(3); a = 16.427(1) ?, b = 4.4721(3) ?, c = 11.9613(7) ?, β = 126.205(1)° for Eu(2)Ag(2)ZnAs(3)), which can be regarded as a stuffed derivative of the Ba(2)Cd(2)Sb(3)-type structure with additional transition-metal atoms in tetrahedral coordination inserted to link the anionic slabs together. The Ag and Zn atoms undergo disorder but with preferential occupancy over four sites centered in either tetrahedral or trigonal planar geometry. The site distribution of these metal atoms depends on a complex interplay of size and electronic factors. All compounds are Zintl phases. Band structure calculations predict that Sr(2)Zn(2)As(3) is a narrow band gap semiconductor and Sr(2)Ag(2)ZnAs(3) is a semimetal. Electrical resistivity measurements revealed band gaps of 0.04 eV for Sr(2)Zn(2)As(3) and 0.02 eV for Eu(2)Zn(2)As(3), the latter undergoing an apparent metal-to-semiconductor transition at 25 K. 相似文献