Trans influence of triphenylphosphines and pseudohalogens on Ni-S bonds of NiS2PN and NiS2PC chromophores has been investigated by synthesizing and characterizing them. The complexes show the characteristic thioureide IR band at ∼ 1530 cm−1. Electronic spectrum of the cyanide analogue shows a strong blue shift relative to others. X-ray structures of [Ni(pipdtc)(4-MP)(NCS)] (1), [Ni(pipdtc)(PPh3)(NCS)] (2) and [Ni(pipdtc)(PPh3)(CN)] (3) (pipdtc = piperidinecarbodithioate anion, 4-MP = tri(4-methylphenyl)phopshine) are reported. Ni-S bond distance trans to 4-MP(1) is longer than the distances in (2) and (3) and Ni-S bond distances trans to Ni-NCS/CN decrease as follows: (3) > (2) > (1). Particularly, 4-MP shows a highly significant trans influence than triphenylphosphine on Ni-S bond. Similarly, CN− exerts a marginally significant trans influence compared to NCS-. Thioureide C-N distances are relatively very short due to the drift of electron density towards the metal. The Ni-N-C angle (163.5(2)°) observed in (2) indicates deviation from linearity to a larger extent compared to that in (1) (176.3(3)°) due to the steric effect of the 4-methyl group. The reduction potentials (CV) for the mixed ligand complexes are much less compared to that of the parent NiS4 chromophore due to the π-acidic phosphines. 相似文献
Consider the diagonal action of
on the affine space
where
an algebraically closed field of characteristic
We construct a "standard monomial" basis for the ring of invariants
As a consequence, we deduce that
is Cohen-Macaulay. As the first application, we present the first and second fundamental theorems for
-actions. As the second application, assuming that the characteristic of K is
we give a characteristic-free proof of the Cohen-Macaulayness of the moduli space
of equivalence classes of semi-stable, rank 2, degree 0 vector bundles on a smooth projective curve of genus > 2. As the
third application, we describe a K-basis for the ring of invariants for the adjoint action of
on m copies of
in terms of traces. 相似文献
Cuplike structures of Au, Ag, Cu, Zn, Nb, Cd, Al, In, and Sn in the size range of 300 nm to a few micrometers with an internal volume of a few femtoliters have been produced by the laser ablation of metal targets in a vacuum, by optimizing, in each case, the laser fluence and the substrate temperature. The metal droplets impinging on the substrate seem to undergo a hydraulic jump driven by the surface tension forces before solidifying into cups. The cups are robust and can be functionalized with biomarkers, filled with nanoparticle sols, oxidized to crucibles, or detached from the substrate without causing any deformation. We envisage their potential applications as femtoliter metal containers. 相似文献
Unilamellar vesicles are observed to form in aqueous solutions of the cationic surfactant, cetyl trimethylammonium bromide (CTAB), when 5-methyl salicylic acid (5mS) is added at slightly larger than equimolar concentrations. When these vesicles are heated above a critical temperature, they transform into long, flexible wormlike micelles. In this process, the solutions switch from low-viscosity, Newtonian fluids to viscoelastic, shear-thinning fluids having much larger zero-shear viscosities (e.g., 1000-fold higher). The onset temperature for this transition increases with the concentration of 5mS at a fixed CTAB content. Small-angle neutron scattering (SANS) measurements show that the phase transition from vesicles to micelles is a continuous one, with the vesicles and micelles coexisting over a narrow range of temperatures. The tunable vesicle-to-micelle transition and the concomitant viscosity increase upon heating may have utility in a range of areas, including microfluidics, controlled release, and tertiary oil recovery. 相似文献
This paper presents stylized models for conducting performance analysis of the manufacturing supply chain network (SCN) in
a stochastic setting for batch ordering. We use queueing models to capture the behavior of SCN. The analysis is clubbed with
an inventory optimization model, which can be used for designing inventory policies . In the first case, we model one manufacturer
with one warehouse, which supplies to various retailers. We determine the optimal inventory level at the warehouse that minimizes
total expected cost of carrying inventory, back order cost associated with serving orders in the backlog queue, and ordering
cost. In the second model we impose service level constraint in terms of fill rate (probability an order is filled from stock
at warehouse), assuming that customers do not balk from the system. We present several numerical examples to illustrate the
model and to illustrate its various features. In the third case, we extend the model to a three-echelon inventory model which
explicitly considers the logistics process. 相似文献
The right path : The mechanism of organocatalyzed Michael addition between propanal and methyl vinyl ketone is investigated using the density functional and ab intio methods. The kinetic preference for the formation of key intermediates is established in an effort to identify the competing pathways associated with the reaction. The effect of co‐catalyst/protic solvent on the energetics of the reaction is also studied