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991.
Dansyl-labeled methionine is synthesized by solid-phase synthesis, and found to be a highly sensitive and selective sensor for Hg(2+). The sensor sensitively detects Hg(2+) ions in aqueous solution by a turn-on response; however, the sensor detects Hg(2+) ions by a turn-off response in organic and mixed aqueous-organic solutions. We investigated the binding stoichiometry, binding constant, and binding mode of the sensor under various solvent conditions. In 100% aqueous solution, 2 : 1 complexation of the sensor with Hg(2+) ions is more favorable than 1 : 1 complexation, whereas the sensor preferentially forms a 1 : 1 complex in 100% CH(3)CN or in 50% CH(3)CN-aqueous solutions. Results reveal that the stoichiometry of the sensor-Hg(2+) complex plays an important role in the type of response to Hg(2+) ions, and that 2 : 1 complexation is required for a turn-on response to Hg(2+) ions in aqueous solution. 相似文献
992.
Chandrika Prasad Raj Krishan Jain Som Raj Soni 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1972,23(6):941-948
Summary Free axisymmetric vibrations of circular plates of linearly varying thickness have been studied on the basis of classical theory of plates. The differential equation governing the motion of such plates have been solved by Frobenius method. The transverse displacement has been expressed as an infinite power series in the radial coordinate. Frequency parameters have been computed for the first three modes of vibration for clamped as well as simply supported circular plates corresponding to different values of taper constant.
Zusammenfassung Auf Grund der klassischen Scheibentheorie werden die freien axialsymmetrischen Schwingungen der Kreisscheibe mit linear veränderlicher Dicke studiert. Die Differentialgleichung der Bewegung wird mit Hilfe der Methode von Frobenius gelöst. Die transversale Verschiebung wird als eine Reihe der radialen Koordinaten ausgedrückt. Die Schwingungsparameter werden für die ersten drei Eigenschwingungen sowohl für die eingespannte als auch für die aufgelegte Kreisscheibe für verschiedene Werte des Anzugs berechnet.相似文献
993.
Bhoj Raj Gautam Igor Dubenko Arjun Kumar Pathak Shane Stadler Naushad Ali 《Journal of magnetism and magnetic materials》2009,321(1):29-33
The influence of the substitution of manganese by boron on the crystal structure and magnetic properties of Ni2Mn1−xBxGa Heusler alloys with 0?x?0.5 has been investigated using X-ray diffraction, thermal expansion, resistivity, and magnetization measurements. The samples with concentrations x<0.25 were found to be of single phase and belonged to the cubic L21 crystal structure at room temperature. Crystal cell parameters of the alloys decreased from 5.830 to 5.825 Å with increasing boron concentration (x) from 0 to 0.25. The alloys were ferromagnetically ordered at 5 K and the saturation magnetization decreased with increasing boron concentration. The ferromagnetic ordering and structural transition temperatures for 0?x?0.3 have been observed and the phase (x−T) diagram of the Ni2Mn1−xBxGa system was constructed. The phase (x−T) diagram indicates that the ground state of Ni2Mn1−xBxGa alloys belongs to ferromagnetic martensitic, premartensitic, and austenitic phases in x?0.12, 0.12<x?0.18, and 0.18<x?0.3, respectively. The relative influence of cell parameters and electron concentrations on the phase diagram is discussed. 相似文献
994.
Igor Dubenko Mahmud Khan Arjun Kumar Pathak Bhoj Raj Gautam Shane Stadler Naushad Ali 《Journal of magnetism and magnetic materials》2009,321(7):754-757
The Mn-based Heusler alloys encompass a rich collection of useful materials from highly spin-polarized systems to shape memory alloys to magnetocaloric materials. In this work we have summarized our studies of magnetostructural transitions from paramagnetic austenite to ferromagnetic martesite phases at TMC in Ni2MnGa-based alloys (Ni2Mn0.75Cu0.25-xCoxGa, Ni2Mn0.70Cu0.30Ga0.95Ge0.05, Ni2Mn1-xCuxGa, Ni2+xMn1-xGa, and Ni2Mn0.75-xCuxGa), and martensitic transitions from the ferromagnetic austenite to the martesite state in off-stoichiometric Ni-Mn-(In/Sb) Heusler alloys. The phase transition temperatures and respective magnetic entropy changes (ΔS) depend on composition in these systems and have been determined from magnetization measurements in the temperature interval 5-400 K, and in magnetic fields up to 5 T. It is shown that, depending on the composition and doping scheme the “giant” ΔS=40-60 J/(kgK) (for a field change of 5 T) can be observed in the temperature range (300-360 K) for the Ga-based alloys. The interplay between or coupling of the various transitions in Ni2Mn(Mn,X) systems with X=Sb and In leads to exchange bias effects, giant magnetoresistance, and both inverse and “normal” magnetocaloric effects. 相似文献
995.
Raj Jagannathan 《Annals of Operations Research》1991,30(1):107-114
In formulating stochastic programming with recourse models, the parameters of the linear programs are usually assumed to be random variables with known distributions. In this paper, the requirement vector parameter is assumed to be a stochastic process {
i
(t),tT,i=1,...,m}. The properties of the deterministic equivalents for the cases of the discrete and continuous index setT are derived. The results of the paper are applied to a multi-item production planning model with continuous (periodic) review of the stock on hand of various items. 相似文献
996.
For graphs F and H, we say F is Ramsey for H if every 2‐coloring of the edges of F contains a monochromatic copy of H. The graph F is Ramsey H‐minimal if F is Ramsey for H and there is no proper subgraph of F so that is Ramsey for H. Burr et al. defined to be the minimum degree of F over all Ramsey H‐minimal graphs F. Define to be a graph on vertices consisting of a complete graph on t vertices and one additional vertex of degree d. We show that for all values ; it was previously known that , so it is surprising that is much smaller. We also make some further progress on some sparser graphs. Fox and Lin observed that for all graphs H, where is the minimum degree of H; Szabó et al. investigated which graphs have this property and conjectured that all bipartite graphs H without isolated vertices satisfy . Fox et al. further conjectured that all connected triangle‐free graphs with at least two vertices satisfy this property. We show that d‐regular 3‐connected triangle‐free graphs H, with one extra technical constraint, satisfy ; the extra constraint is that H has a vertex v so that if one removes v and its neighborhood from H, the remainder is connected. 相似文献
997.
Dr. Huiling Shao Dr. Victor Adebomi Angele Bruce Prof. Dr. Monika Raj Prof. Dr. Kendall N. Houk 《Angewandte Chemie (International ed. in English)》2023,62(41):e202307210
Macrocyclic peptides have become increasingly important in the pharmaceutical industry. We present a detailed computational investigation of the reaction mechanism of the recently developed “CyClick” chemistry to selectively form imidazolidinone cyclic peptides from linear peptide aldehydes, without using catalysts or directing groups (Angew. Chem. Int. Ed. 2019 , 58, 19073–19080). We conducted computational mechanistic to investigate the effects of intramolecular hydrogen bonds (IMHBs) in promoting a kinetically facile zwitterionic mechanism in “CyClick” of pentapeptide aldehyde AFGPA. Our DFT calculations highlighted the importance of IMHB in pre-organization of the resting state, stabilization of the zwitterion intermediate, and the control of the product stereoselectivity. Furthermore, we have also identified that the low ring strain energy promotes the “CyClick” of hexapeptide aldehyde AAGPFA to form a thermodynamically more stable 15+5 imidazolidinone cyclic peptide product. In contrast, large ring strain energy suppresses “CyClick” reactivity of tetra peptide aldehyde AFPA from forming the 9+5 imidazolidinone cyclic peptide product. 相似文献
998.
p-PhOC6H4TeCl3 crystallises with a dimeric molecular unit. The two approximately square pyramidal coordination polyhedra are linked trans to each other through two bridging chlorine atoms. The dimeric units are further connected through Te…Cl secondary interactions producing a distorted octahedral geometry about each tellurium atom. The crystals are triclinic, space group P, with unit cell dimensions a 8.521(2), b 10.917(2), c 14.813(2) Å, α 81.84(1), β 83.38(1), γ 88.41(1)°, V 1353.4(4) Å3 and Z = 2(dimers) from 3887 observed reflections [I > 3σ(I)], R = 0.0359. 相似文献
999.
Korb O Ten Brink T Victor Paul Raj FR Keil M Exner TE 《Journal of computer-aided molecular design》2012,26(2):185-197
Due to the large number of different docking programs and scoring functions available, researchers are faced with the problem
of selecting the most suitable one when starting a structure-based drug discovery project. To guide the decision process,
several studies comparing different docking and scoring approaches have been published. In the context of comparing scoring
function performance, it is common practice to use a predefined, computer-generated set of ligand poses (decoys) and to reevaluate
their score using the set of scoring functions to be compared. But are predefined decoy sets able to unambiguously evaluate
and rank different scoring functions with respect to pose prediction performance? This question arose when the pose prediction
performance of our piecewise linear potential derived scoring functions (Korb et al. in J Chem Inf Model 49:84–96, 2009) was assessed on a standard decoy set (Cheng et al. in J Chem Inf Model 49:1079–1093, 2009). While they showed excellent pose identification performance when they were used for rescoring of the predefined decoy conformations,
a pronounced degradation in performance could be observed when they were directly applied in docking calculations using the
same test set. This implies that on a discrete set of ligand poses only the rescoring performance can be evaluated. For comparing
the pose prediction performance in a more rigorous manner, the search space of each scoring function has to be sampled extensively
as done in the docking calculations performed here. We were able to identify relative strengths and weaknesses of three scoring
functions (ChemPLP, GoldScore, and Astex Statistical Potential) by analyzing the performance for subsets of the complexes
grouped by different properties of the active site. However, reasons for the overall poor performance of all three functions
on this test set compared to other test sets of similar size could not be identified. 相似文献