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31.
Is it True That the Normal Valence‐Length Correlation Is Irrelevant for Metal–Metal Bonds? 下载免费PDF全文
Dr. Vijay Singh Dr. Mudit Dixit Dr. Monica Kosa Prof. Dan Thomas Major Prof. Elena Levi Prof. Dr. Doron Aurbach 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(15):5269-5276
The most intriguing feature of metal–metal bonds in inorganic compounds is an apparent lack of correlation between the bond order and the bond length. In this study, we combine a variety of literature data obtained by quantum chemistry and our results based on the empirical bond valence model (BVM), to confirm for the first time the existence of a normal exponential correlation between the effective bond order (EBO) and the length of the metal–metal bonds. The difference between the EBO and the formal bond order is attributed to steric conflict between the (TM)n cluster (TM=transition metal) and its environment. This conflict, affected mainly by structural type, should cause high lattice strains, but electron redistribution around TM atoms, evident from the BVM calculations, results in a full or partial strain relaxation. 相似文献
32.
A sequence of coefficients that appeared in the evaluation of a rational integral has been shown to be unimodal. The original proof is based on a inequality for hypergeometric functions. A generalization is presented. 相似文献
33.
W.C. Sperry G.A. Beer M.S. Dixit S.K. Kim J.A. MacDonald G.R. Mason A. Olin R.M. Pearce C. Sabev C. Wiegand 《Physics letters. [Part B]》1979,86(1):29-30
The intensity per stopped π?of|Δn|=2 pionic X-rays are observed to have larger variations with atomic number Z than do the |Δn|=1. The 6–4 intensity has a well-defined maximum at Z=34 with a FWHM of ΔZ ~10. 相似文献
34.
Bulk d.c. conductivities of the electronically conducting transition metal oxide glasses in the system xV2O550B2O3(50?x)TeO2 were measured at different temperatures in the range 310–623 K. The dependence of conductivity on composition is explained on the basis of the role of TeO2 as a modifier or impurity. The observed kink in the log σ vs 1/T characteristic of the glasses is interpreted as being due to switching over of the conduction mechanism from one type to the other. The activation energies are fitted in a linear relation of the type Eg = A ? BP, where A and B are constants and P, the composition parameter. Comparing the results obtained with those of previous workers in the V2O5P2O5 and V2O5B2O3 systems, a physical analysis is presented. 相似文献
35.
Dewald EL Suter LJ Landen OL Holder JP Schein J Lee FD Campbell KM Weber FA Pellinen DG Schneider MB Celeste JR McDonald JW Foster JM Niemann C Mackinnon AJ Glenzer SH Young BK Haynam CA Shaw MJ Turner RE Froula D Kauffman RL Thomas BR Atherton LJ Bonanno RE Dixit SN Eder DC Holtmeier G Kalantar DH Koniges AE Macgowan BJ Manes KR Munro DH Murray JR Parham TG Piston K Van Wonterghem BM Wallace RJ Wegner PJ Whitman PK Hammel BA Moses EI 《Physical review letters》2005,95(21):215004
The first hohlraum experiments on the National Ignition Facility (NIF) using the initial four laser beams tested radiation temperature limits imposed by plasma filling. For a variety of hohlraum sizes and pulse lengths, the measured x-ray flux shows signatures of filling that coincide with hard x-ray emission from plasma streaming out of the hohlraum. These observations agree with hydrodynamic simulations and with an analytical model that includes hydrodynamic and coronal radiative losses. The modeling predicts radiation temperature limits with full NIF (1.8 MJ), greater, and of longer duration than required for ignition hohlraums. 相似文献
36.
Embryogenic tissues of Dioscorea bulbifera were cryopreserved using the encapsulation-dehydration technique. Genetic stability of plants regenerated from cryopreserved embryogenic tissues was assessed using molecular, biochemical and morphological analysis. The random amplified polymorphic DNA (RAPD) analysis of 60 cryopreserved-derived and 20 in vitro grown (control) plantlets showed that 10 primers produced 62 clear reproducible DNA fragment profiles. The amplification products were monomorphic for all the plantlets except one. A total of 4960 DNA fragments were obtained from this study showing no variation in RAPD profiles. The diosgenin content of cryopreserved-derived plants, analyzed using HPLC, was similar to that of control plants. Morphology and the ability to form microtuber were also found to be unaltered in cryopreserved embryo-derived plantlets. Thus, the D. bulbifera plants regenerated from cryopreserved embryogenic tissues were genetically stable at the molecular, biochemical and morphological levels. 相似文献
37.
Rahul P. Dixit Chandrashekhar R. Barhate Mangal S. Nagarsenker 《Chromatographia》2008,67(1-2):101-107
Simvastatin and ezetimibe are used to treat hyperlipidemia. A simple, selective and stability-indicating HPTLC method has
been established for analysis of simvastatin and ezetimibe. The method has been validated so that both drugs can routinely
be analyzed simultaneously. The method uses aluminum-backed silica gel 60F254 TLC plates as stationary phase with n-hexane–acetone 6:4 (v/v) as mobile phase. Densitometric analysis of both drugs was carried out in absorbance mode at 234 nm. This system was found
to give compact bands for simvastatin and ezetimibe (R
F 0.39 ± 0.05 and 0.50 ± 0.05, respectively). Linear relationships were obtained between response and amount of drug in the
range 200–1,600 ng per band with high correlation coefficients (r
2 = 0.9917 ± 0.0018 for simvastatin and r
2 = 0.9927 ± 0.0021 for ezetimibe). The method was validated for precision, robustness, and recovery. The limits of detection
and quantitation were 25 and 150 ng per band, respectively. Simvastatin and ezetimibe were subjected degradation by acid,
pH 6.8 phosphate buffer, oxidation, dry heat, and wet heat. The degradation products were well resolved from the pure drug
with significantly different R
F values. Because the method could effectively separate the drug from its degradation products, it can be used for stability-indicating
analysis. 相似文献
38.
G. Dixit J. P. Singh R. C. Srivastava H. M. Agrawal R. J. Choudhary A. Gupta 《Surface and interface analysis : SIA》2010,42(3):151-156
Nickel ferrite is a soft magnetic material with inverse spinel structure. Soft ferrite films are used in microwave devices, integrated planar circuits, etc., because of their high resistivity. In this work, thin films of nickel ferrite were deposited on Si (100) substrate by using pulsed laser deposition (PLD) technique. The thickness of the film was measured by surface profilometer and also by X‐ray reflectivity (XRR). The films were annealed at three different temperatures to observe the effect on the structural and magnetic properties of the film. The films were characterised by X‐ray diffraction (XRD), Raman spectroscopy and vibrating sample magnetometer (VSM) to study the structural and magnetic properties. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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