Steady-state master equation methods

This paper investigates the application of the steady-state master equation (SSME) to complex unimolecular reactions. It is shown how the steady-state approximation and the Boltzmann reservoir approximation can be applied, both together or separately, to improve the efficiency and the numerical robustness of simple master equation calculations. The case of a two-well isomerization is considered in detail, and two versions of the SSME are derived for it, one of which shows very clearly and analytically the relationship between the rate coefficients and the flux coefficients. It is shown for a reversible second order recombination reaction that the second order phenomenological equation can be regained in either version of the SSME. It is also shown how, under steady state conditions, the SSME may be used to determine rate coefficients for each reaction in a multiple well scheme.     

An Intricate Review on Nutritional and Analytical Profiling of Coconut,Flaxseed, Olive,and Sunflower Oil Blends

Vegetable oils (VOs), being our major dietary fat source, play a vital role in nourishment. Different VOs have highly contrasting fatty acid (FA) profiles and hence possess varying levels of health protectiveness. Consumption of a single VO cannot meet the recommended allowances of various FA either from saturated FA (SFA), monounsaturated FA (MUFA), polyunsaturated FA (PUFA), Ω-3 PUFAs, and medium-chain triglycerides (MCTs). Coconut oil (CO), flaxseed oil (FO), olive oil (OO), and sunflower oil (SFO) are among the top listed contrast VOs that are highly appreciated based on their rich contents of SFAs, Ω-3 PUFAs, MUFAs, and Ω-6 PUFA, respectively. Besides being protective against various disease biomarkers, these contrasting VOs are still inappropriate when consumed alone in 100% of daily fat recommendations. This review compiles the available data on blending of such contrasting VOs into single tailored blended oil (BO) with suitable FA composition to meet the recommended levels of SFA, MUFA, PUFA, MCTs, and Ω-3 to Ω-6 PUFA ratios which could ultimately serve as a cost-effective dietary intervention towards the health protectiveness and improvement of the whole population in general. The blending of any two or more VOs from CO, FO, OO, and SFO in the form of binary, ternary, or another type of blending was found to be very conclusive towards balancing FA composition; enhancing physiochemical and stability properties; and promising the therapeutic protectiveness of the resultant BOs.     

Dynamics of ternary complex formation in the reaction of diaquoanthranilato-N,N-diacetatonickelate(II) with 2,2′-bipyridine and 1,10-phenanthroline

Dynamics of ternary complex formation in the reaction of diaquoanthranilato-N, N-diacetatonickelate(II) with 2,2′-bipyridine and 1,10-phenanthroline. $\rm Ni(ada)(H_2O)_2^{-}$ $+$ $L\rightleftharpoons Ni(ada)(L)^{-}$ $+$ $2 H_20;$ $- {{d[Ni(ada)^{-}]}\over{dt}}$ $=$ $k_f[Ni(ada)^{-}][L]+k_d\ [Ni(ada)(L)];$ $\ ada^{3-}=$anthranilate-N, N-diacetate; and L=bipy or phen. The kinetics of formation of ternary complexes by diaquoanthranilato-N, N-diacetatonickelate(II). [Ni(ada)(H₂O)]⁻ with 2,2′-bipyridine (bipy) and 1,10-phenanthroline (phen) have been studied under pseudo-first-order conditions containing excess bipy or phen by stopped-flow spectrophotometry in the pH range 7.1–7.8 at 25°C and λ = 0.1 mol dm⁻³. In each case, the reaction is first-order with respect to both Ni(ada)⁻ and the entering ligand (ie., bipy, phen). The reactions are reversible. The forward rate constants are: $k^{\rm Ni(ada)}_{\rm Ni(ada)(bipy)}=0.87\times10^3{\rm dm}^3 {\rm mol}^{-1}{\rm s}^{-1}$, . $k^{\rm Ni(ada)}_{\rm Ni(ada)(phen)}=1.87\times10^3{\rm dm}^3 {\rm mol}^{-1}{\rm s}^{-1}$; and the reverse rate constants are: $k^{\rm Ni(ada)(bipy)}_{\rm Ni(ada)}=1.0{\rm s}^{-1}$ and $k^{\rm Ni(ada)(phen)}_{\rm Ni(ada)}=2.0{\rm s}^{-1}$. The corresponding stability constants of ternary complex formation are: and , . The observed rate constants and huge drops in stability constants in ternary complex formation agree well with the mechanism in which dissociation of an acetate arm of the coordinated ada³⁻ prior to chelation by the aromatic ligand occurs. The observations have been compared with the kinetics of ternary complex formation in the reaction Ni(ada)⁻ - glycine in which the kinetics involves a singly bonded intermediate, N(ada)((SINGLE BOND)O(SINGLE BOND)N)²⁻ in rapid equilibrium with the reactants followed by a sluggish ring closure step. The reaction with the aromatic ligands conforms to a steady-state mechanism, while for glycine it gets shifted to an equilibrium mechanism. The cause of this difference in mechanistic pathways has been explained. © 1996 John Wiley & Sons, Inc.     

Chloro-diorganotin(IV) complexes of 4-methyl-1-piperidine carbodithioic acid: Synthesis, X-ray crystal structures, spectral properties and antimicrobial studies

Chloro-diorganotin(IV) complexes of 4-methyl-1-piperidine carbodithioic acid (4-MePCDTA) have been synthesized by the reaction with diorganotin dichloride in 1:1 molar ratio in anhydrous toluene. These newly synthesized complexes have been characterized by elemental, IR, multinuclear NMR (¹H and ¹³C) and mass spectrometric studies. The crystal structures of complex 1 [Me₂SnCl(4-MePCDT)] and 3 [Ph₂SnCl(4-MePCDT)] have been determined by X-ray single crystal analysis, which show trigonal bipyramid geometry. These complexes were tested for their antimicrobial activity against six different plant and human pathogens. The screening results show that the complexes exhibit higher antibacterial and antifungal activity than the free ligand.     

An enzymatic approach to the desymmetrization of disubstituted pyrrolines

The enzymatic desymmetrization of 2,2- and 2,5-disubstituted pyrroline compounds is reported in a procedure which gives access to both enantiomers in excellent enantiomeric excess and good yield. The enzyme reaction precursors are formed easily from two readily available substituted pyrroles using both ammonia (Na/NH3) and ammonia-free (Li/DBB) Birch reduction conditions.     

Energy conditions in modified <Emphasis Type="Italic">f</Emphasis>(<Emphasis Type="Italic">G</Emphasis>) gravity

In this paper, we have considered flat Friedmann–Lemaître–Robertson–Walker metric in the framework of perfect fluid models and modified f(G) gravity (where G is the Gauss Bonnet invariant). Particularly, we have considered particular realistic f(G) configurations that could be used to cure finite-time future singularities arising in the late-time cosmic accelerating epochs. We have then developed the viability bounds of these models induced by weak and null energy conditions, by using the recent estimated numerical figures of the deceleration, Hubble, snap and jerk parameters.     

Large scale silver nanowires network fabricated by MeV hydrogen(H~+) ion beam irradiation

A random two-dimensional large scale nano-network of silver nanowires(Ag-NWs) is fabricated by MeV hydrogen(H~+) ion beam irradiation. Ag-NWs are irradiated under H~+ion beam at different ion fluences at room temperature. The Ag-NW network is fabricated by H~+ion beam-induced welding of Ag-NWs at intersecting positions. H~+ion beam induced welding is confirmed by transmission electron microscopy(TEM) and scanning electron microscopy(SEM). Moreover, the structure of Ag NWs remains stable under H~+ion beam, and networks are optically transparent. Morphology also remains stable under H~+ion beam irradiation. No slicings or cuttings of Ag-NWs are observed under MeV H~+ion beam irradiation.The results exhibit that the formation of Ag-NW network proceeds through three steps: ion beam induced thermal spikes lead to the local heating of Ag-NWs, the formation of simple junctions on small scale, and the formation of a large scale network. This observation is useful for using Ag-NWs based devices in upper space where protons are abandoned in an energy range from MeV to GeV. This high-quality Ag-NW network can also be used as a transparent electrode for optoelectronics devices.     

Search for a Higgs boson in the diphoton final state in pp collisions at sqrt[s]=1.96 TeV

A search for a narrow Higgs boson resonance in the diphoton mass spectrum is presented based on data corresponding to 7.0 fb{-1} of integrated luminosity from pp collisions at sqrt[s]=1.96 TeV collected by the CDF experiment. No evidence of such a resonance is observed, and upper limits are set on the cross section times branching ratio of the resonant state as a function of Higgs boson mass. The limits are interpreted in the context of the standard model and one fermiophobic benchmark model where the data exclude fermiophobic Higgs bosons with masses below 114 GeV/c{2} at a 95% Bayesian credibility level.     

Precise measurement of the W-boson mass with the CDF II detector

We have measured the W-boson mass M(W) using data corresponding to 2.2 fb(-1) of integrated luminosity collected in pp collisions at sqrt[s] = 1.96 TeV with the CDF II detector at the Fermilab Tevatron collider. Samples consisting of 470,126 W → eν candidates and 624,708 W → μν candidates yield the measurement M(W) = 80,387 ± 12(stat.) ± 15(syst.) = 80,387 ± 19 MeV/c2. This is the most precise measurement of the W-boson mass to date and significantly exceeds the precision of all previous measurements combined.