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11.
Summary Di--chlorobis(arylazooximato)dipalladiuni(II) compounds react with PPh3 to give the four-coordinate complexes (5) and (4) in which the azooxime acts as a unidentate and bidentate ligand respectively. Hydrogen bonding in polar solvents such as MeOH or EtOHetc. stabilize (5) whereas, polar solvents such as Me2CO, py and Et2O convert (5) into (4). The equilibrium: (4) + PPh3 (5) exists in PhH solution and equilibrium constants at 30°C have been calculated spectrophotometrically. The variation in equilibrium constants and the stabilities of (5) have been explained on the basis of electron-releasing and electron-withdrawing properties of substituents, R, in the azooxime ligand. 相似文献
12.
A zero-dimensional zinc phosphate, comprising a 4-membered ring, is shown to spontaneously transform at room temperature, to a linear chain structure consisting of corner-shared 4-membered rings, the latter transforming to a 3-dimensional sodalite-related structure under mild conditions. 相似文献
13.
This paper studies a scheduling control problem for a single-server multiclass queueing network in heavy traffic, operating in a changing environment. The changing environment is modeled as a finite-state Markov process that modulates the arrival and service rates in the system. Various cases are considered: fast changing environment, fixed environment, and slowly changing environment. In all cases, the arrival rates are environment dependent, whereas the service rates are environment dependent when the environment Markov process is changing fast, and are assumed to be constant in the other two cases. In each of the cases, using weak convergence analysis, in particular functional limit theorems for Poisson processes and ergodic Markov processes, it is shown that an appropriate “averaged” version of the classical \(c\mu \) -policy (the priority policy that favors classes with higher values of the product of holding cost \(c\) and service rate \(\mu \) ) is asymptotically optimal for an infinite horizon discounted cost criterion. 相似文献
14.
The interaction of 1-anilinonaphthalene-8-sulphonate (ANS) with cross-linked poly(N-vinyl-2-pyrrolidone) (CPVP) was studied
by the adsorption technique at different temperatures and at two different pH values. Analysis by the Scatchard method and
the study made in the presence of urea showed that the iceberg structure of water affects the sorption of ANS to CPVP, leading
to cooperativity. The observed Giles sorption isotherms at both the pH values were of theL-type which indicated the interaction of ANS in flat configuration with the binding site in CPVP. The sorption of ANS to CPVP
was enhanced considerably at acidic pH due to some structural factors which also resulted in multilayer sorption at this pH.
Comparison of binding of ANS to CPVP and to linear poly(N-vinyl-2-pyrrolidone) demonstrated the greater contribution of hydrophobic
interaction in CPVP than in the linear polymer. 相似文献
15.
The Contrasting Recognition Behavior of β‐Cyclodextrin and Its Sulfobutylether Derivative towards 4′,6‐Diamidino‐2‐phenylindole 下载免费PDF全文
Meenakshi N. Shinde Dr. Achikanath C. Bhasikuttan Dr. Jyotirmayee Mohanty 《Chemphyschem》2015,16(16):3425-3432
The noncovalent interactions between 4′, 6‐diamidino‐2‐phenylindole (DAPI) and sulfobutylether β‐cyclodextrin (SBE7β‐CD) are evaluated by using photochemical measurements and compared with that of native β‐CD. Contrasting recognition behavior and intriguing modulations in the photochemical behavior of DAPI were observed. In particular, a large enhancement in the fluorescence emission and excited‐state lifetime were seen upon binding to SBE7β‐CD, with the SBE7β‐CD inclusion complex being approximately 1000 times stronger than that of β‐CD. The ensuing fluorescence “turn on” was demonstrated to be responsive to chemical stimuli, such as metal ions and adamantylanmine (AD). Upon addition of Ca2+/AD, nearly quantitative dissociation of the complex was established to regenerate the free dye and result in fluorescence “turn off”. The SO3? groups are believed to be critical for the strong and selective binding of the chromophore and the stimuli‐responsive tuning. This is as an important design criterion for the optimization of host–guest properties through supramolecular association, which is relevant for drug‐delivery applications. 相似文献
16.
Bhim Bali Prasad Khushaboo Tiwari Meenakshi Singh Piyush S. Sharma Amit K. Patel Shrinkhala Srivastava 《Chromatographia》2009,69(9-10):949-957
A combination approach in solid-phase microextraction, based on a molecularly imprinted polymer-brush coating on an optical fiber coupled with a complementary molecularly imprinted polymer sensor, has been adopted for isolation, preconcentration, and analysis of dopamine at ultratrace levels in highly dilute aqueous samples. This combination enabled enhanced (up to 8.5-fold) preconcentration of the analyte, which is appropriate for achieving a stringent detection limit in clinical diagnosis of several neurodegenerative diseases. The detection limit of dopamine in biological samples was 0.018 ng mL?1 with a relative standard deviation less than 2.1% and without any non-specific contributions. 相似文献
17.
Vinod Chhokar Meenakshi Sangwan Vikas Beniwal Kiran Nehra Kaur S. Nehra 《Applied biochemistry and biotechnology》2010,160(8):2256-2264
Tannase from Aspergillus awamori MTCC 9299 was purified using ammonium sulfate precipitation followed by ion-exchange chromatography. A purification fold
of 19.5 with 13.5% yield was obtained. Temperature of 30 °C and pH of 5.5 were found optimum for tannase activity. The effects
of metals and organic solvents on the activity of tannase were also studied. Metal ions Mg+2, Mn+2, Ca+2, Na+, and K
+
stimulated the tannase activity, while Cu+2, Fe+3, and Co+2 acted as inhibitors of the enzyme. The addition of organic solvents like acetic acid, isoamylalcohol, chloroform, isopropyl
alcohol, and ethanol completely inhibited the enzyme activity. However, butanol and benzene increased the enzyme activity. 相似文献
18.
Shankar Bhamidi Amarjit Budhiraja Xuan Wang 《Probability Theory and Related Fields》2014,160(3-4):733-796
Random graph models with limited choice have been studied extensively with the goal of understanding the mechanism of the emergence of the giant component. One of the standard models are the Achlioptas random graph processes on a fixed set of \(n\) vertices. Here at each step, one chooses two edges uniformly at random and then decides which one to add to the existing configuration according to some criterion. An important class of such rules are the bounded-size rules where for a fixed \(K\ge 1\) , all components of size greater than \(K\) are treated equally. While a great deal of work has gone into analyzing the subcritical and supercritical regimes, the nature of the critical scaling window, the size and complexity (deviation from trees) of the components in the critical regime and nature of the merging dynamics has not been well understood. In this work we study such questions for general bounded-size rules. Our first main contribution is the construction of an extension of Aldous’s standard multiplicative coalescent process which describes the asymptotic evolution of the vector of sizes and surplus of all components. We show that this process, referred to as the standard augmented multiplicative coalescent (AMC) is ‘nearly’ Feller with a suitable topology on the state space. Our second main result proves the convergence of suitably scaled component size and surplus vector, for any bounded-size rule, to the standard AMC. This result is new even for the classical Erd?s–Rényi setting. The key ingredients here are a precise analysis of the asymptotic behavior of various susceptibility functions near criticality and certain bounds from Bhamidi et al. (The barely subcritical regime. Arxiv preprint, 2012) on the size of the largest component in the barely subcritical regime. 相似文献
19.
JPC – Journal of Planar Chromatography – Modern TLC - The normal-phase (NP) and reversed-phase (RP) thin-layer chromatographic separations of aminoglycosides (streptomycin, kanamycin,... 相似文献
20.
New parameters which separately take into account the effects of elastic anisotropy and phonon dispersion on the lattice specific
heat in the case of fcc metals have been evaluated. A new graded mesh method which uses 162-direction approximation in (1/16)
part of the Brillouin zone has been developed to evaluate the two new parameters. 相似文献