Measuring flux distributions for diffusion in the small-numbers limit

For the classical diffusion of independent particles, Fick's law gives a well-known relationship between the average flux and the average concentration gradient. What has not yet been explored experimentally, however, is the dynamical distribution of diffusion rates in the limit of small particle numbers. Here, we measure the distribution of diffusional fluxes using a microfluidics device filled with a colloidal suspension of a small number of microspheres. Our experiments show that (1) the flux distribution is accurately described by a Gaussian function; (2) Fick's law, that the average flux is proportional to the particle gradient, holds even for particle gradients down to a single particle difference; (3) the variance in the flux is proportional to the sum of the particle numbers; and (4) there are backward flows, where particles flow up a concentration gradient, rather than down it. In addition, in recent years, two key theorems about nonequilibrium systems have been introduced: Evans' fluctuation theorem for the distribution of entropies and Jarzynski's work theorem. Here, we introduce a new fluctuation theorem, for the fluxes, and we find that it is confirmed quantitatively by our experiments.     

Ligand free,highly efficient synthesis of diaryl ether over copper fluorapatite as heterogeneous reusable catalyst

A novel ligand-free, highly efficient, and an inexpensive method has been developed by using ecofriendly, heterogeneous reusable copper fluorapatite (CuFAP) catalyst for the synthesis of diaryl ethers from the cross coupling reaction of the various substituted aryl halides (fluoride, chloride, bromide, and iodide) with the potassium salts of various substituted phenols in the presence of N-methyl 2-pyrrolidone (NMP) as a solvent at 120 °C. The protocol obtained the corresponding cross coupling products in good to excellent yield. The CuFAP catalyst was recovered by simple filtration from the reaction mixture and reused several times without the loss of catalytic activity.     

Electrochromic properties of spray deposited TiO2-doped WO3 thin films

TiO₂-doped WO₃ thin films were deposited onto fluorine-doped tin oxide coated conducting glass substrates using spray pyrolysis technique at 525 °C. The volume percentage of TiO₂ dopant was varied from 13% to 38%. The thin film samples were transparent, uniform and strongly adherent to the substrates. Electrochromical properties of TiO₂-doped WO₃ thin films were studied with the help of cyclic voltammetry (CV), chronoamperometry (CA) and chronocoulometry (CC) techniques. It has been found that TiO₂ doping in WO₃ enhances its electrochromic performance. Colouration efficiency becomes almost double and samples exhibit increasingly high reversibility with TiO₂ doping concentrations, in the studied range.     

Acoustical Studies of Schiff Bases in 1,4-dioxane and Dimethylformamide at 308.15K

Variousworkershavereportedthepreparation,chemicalandphysicalpropertiesofvariousSchiffbases犤1-5犦.Schiffbasesareknowntobeimportantduetotheirapplicationsintheprepa-rationofdyes,liquidcrystalsandpowerfulcorrosionin-hibitors.Furthermore,theyareusedinthemecha…     

Rotational dynamics of UVITEX-OB in alkanes, alcohols and binary mixtures

Steady-state and time resolved fluorescence anisotropy measurements were carried out to study the rotational diffusion dynamics of UVITEX-OB (U-OB) in series of alcohols, alkanes and binary mixtures of toluene and butanol at room temperature. The experimentally measured rotational reorientation times were compared with those estimated by the hydrodynamic and molecular models developed for microscopic friction. The experimental results are in good agreement with theoretical slip hydrodynamics and a deviation towards subslip behavior is noted. Also a faster rotation of the probe in binary mixture of toluene and butanol is noted as compared to that in alcohols and alkanes.     

Effect of pretreatment of molasses and posttreatment of fermented broth in industrial production of ethanol

The aim of preclarification is to minimize sludge going to yeast separators. This purpose is partially fulfilled. However, it has been measured during the plant trial runs that preclarification does not noticeably improve fermentation. The aim of postclarification is to minimize sludge going to distillation. This purpose is well served as noted from the fact that cycle run of distillation columns using postclarification is three times longer (9–12 mo) as compared to the normal one (3–4 mo).     

Simultaneous Determination of Pioglitazone and Glimepiride by High-Performance Thin-Layer Chromatography

JPC – Journal of Planar Chromatography – Modern TLC -     

Sensitive,Selective, Precise and Accurate LC–MS Method for Determination of Clonidine in Human Plasma

A selective and sensitive liquid chromatography–mass spectrometric method in ESI (+ve) mode was developed and validated completely in human plasma. Clonidine and IS, carbamazapine, were extracted from human plasma via liquid–liquid extraction with ethyl acetate. Following evaporation under nitrogen, the residue was reconstituted with mobile phase and analyzed using API 4000 LC–MS–MS system. An isocratic program with binary mobile phases (0.1% formic acid in water and acetonitrile) was used to separate interference peaks by a C18 analytical column. Linearity range was 0.49–73.98 ng mL⁻¹. The intra- and inter-day accuracy and precision were within acceptable limits (≤15%). This method was successfully applied to a single dose 25 μg tablets BE study of clonidine in healthy male volunteers.

     

Potential of <Emphasis Type="Italic">Crocus sativus</Emphasis> (saffron) and its Constituent,Crocin, as Hypolipidemic and Antioxidant in Rats

The aim of the present study was to evaluate the hypolipidemic and antioxidant potential of saffron and its active constituent, crocin, in hyperlipidemic rats. The animals fed either with normal fat diet or high fat diet were administered orally saffron (25, 50, and 100 mg/kg) or crocin (4.84, 9.69, and 19.38 mg/kg) in their respective groups for five consecutive days. Biochemical estimations of triglyceride (TG), total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), alkaline phosphatase (ALP), aspartate transaminase (AST), alanine aminotransferase (ALT), malondialdehyde (MDA), glutathione peroxidase enzyme activity (GSHPx), total glutathione (GSH), and oxidized glutathione (GSSG) in serum and superoxide dismutase (SOD), catalase (CAT), thiobarbituric acid reactive species (TBARS), ferric reducing/antioxidant power (FRAP), and total sulfhydryl (SH) groups in liver tissue homogenate were carried out. Both saffron and crocin were effective in decreasing the elevated levels of TG, TC, ALP, AST, ALT, MDA, GSHPx, GSH, and GSSG in serum and increasing SOD, CAT, FRAP, and SH values in liver tissue with reduction in TBARS. The saffron was found to be superior to crocin indicating the involvement of other potential constituents of saffron apart from crocin for its synergistic behavior of quenching the free radicals and ameliorating the damages of hyperlipidemia.     

Dual fluorescence and laser emissions from fluorescein-Na and eosin-B

Dual laser emissions were observed from fluorescein-Na and eosin-B in ethanolic solutions individually in the concentration range from 10⁻² to 10⁻³ mol dm⁻³ under N₂ laser excitation. The first compound was found to lase at two distinct regions with wavelength maxima around 540, 550 nm, while the second one around 558, 574 nm. Steady-state absorption, fluorescence excitation, fluorescence polarization, fluorescence emission and decays of the dyes in various solvents under varying conditions of excitation and detection systems were carried out to identify the nature of the emitting species responsible for laser emissions in two distinct regions. Both the dyes exhibited concentration and excitation wavelength dependence of fluorescence and the effects were found to be more pronounced in binary solution. The fluorescence decays of dyes were monoexponential in ethanol, while in some other solvents used, the decays showed biexponential behavior. The absorption and excitation studies using thin layers of solutions revealed the formation of dimers with the dye concentration around 1×10⁻³ mol dm⁻³. Fluorescence polarization and decay studies confirmed the presence of dimers. The two laser bands observed in the shorter and longer wavelengths were respectively ascribed to monomeric and dimeric species.