Convective Instability in Superposed Fluid and Porous Layers with Vertical Throughflow

A closed form solution to the convective instability in a composite system of fluid and porous layers with vertical throughflow is presented. The boundaries are considered to be rigid-permeable and insulating to temperature perturbations. Flow in the porous layer is governed by Darcy–Forchheimer equation and the Beavers–Joseph condition is applied at the interface between the fluid and the porous layer. In contrast to the single-layer system, it is found that destabilization due to throughflow arises, and the ratio of fluid layer thickness to porous layer thickness, , too, plays a crucial role in deciding the stability of the system depending on the Prandtl number.     

Synthesis, spectroscopic characterization, and antimicrobial activity of cobalt(II) complexes of acetone-N(4)-phenylsemicarbazone: crystal structure of [Co(HL)2(MeOH)2](NO3)2

Four Co(II) complexes, [Co(HL)₂](OAc)₂, [Co(HL)₂Cl₂], [Co(HL)₂(MeOH)₂](NO₃)₂, and [Co₂(HL)₄(SO₄)₂] (HL = acetone-N(4)-phenylsemicarbazone) were synthesized and characterized by physicochemical and spectroscopic methods. The magnetic susceptibility measurements indicate that the complexes are paramagnetic with three unpaired electrons. In all the complexes, the semicarbazone is coordinated as a neutral bidentate ligand. The structure of [Co(HL)₂(MeOH)₂](NO₃)₂ was confirmed by single crystal X-ray crystallography. The ligand is neutral and bidentate, being coordinated to the cobalt atom through the carbonyl oxygen and the azomethine nitrogen. Intermolecular hydrogen bonding and C–H···π interactions combine to stabilize the crystal structure. The ligand and its two complexes [Co(HL)₂Cl₂] and [Co(HL)₂(MeOH)₂](NO₃)₂ were screened for their antibacterial and antifungal activities using disk diffusion methods.     

Graphene oxide/copper terephthalate composite as a sensing platform for nitrite quantification and its application to environmental samples

Journal of Solid State Electrochemistry - A robust electrochemical sensing platform based on graphene oxide-copper terephthalate (GO/Cu-tpa) composite has been fabricated. The prepared composite...     

Effect of the pore surface modification of an inorganic substrate on the plasma‐grafting behavior of pore‐filling‐type organic/inorganic composite membranes

We have investigated the effect of the surface state and surface treatment of the pores of an inorganic substrate on the plasma‐grafting behavior of pore‐filling‐type organic/inorganic composite membranes. Shirasu porous glass (SPG) was used as the inorganic substrate, and methyl acrylate was used as the grafting monomer. The grafting rate increased as the density of silanol on the SPG substrate increased. This result suggests that radicals are generated mainly at the silanol groups on the pore surface by plasma irradiation. The SPG substrates were treated with silane coupling agents used to control the mass of organic material bonded to the pore surface. The thickness of the grafted layer became thinner as the mass of organic material bonded to the pore surface of SPG increased. This decrease in the thickness of the grafted layer could be explained by the decrease in the penetration depth of vacuum ultraviolet rays contained in plasma having a wavelength of less than 160 nm that generated radicals in the pores of the substrate. The thickness of the grafted layer inside the SPG substrates could be controlled through the control of the mass of organic material bonded to the pore surface of the SPG substrate. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 846–856, 2006     

Kinetics and mechanisms of the allyl + allyl and allyl + propargyl recombination reactions

The kinetics and mechanisms of the self-reaction of allyl radicals and the cross-reaction between allyl and propargyl radicals were studied both experimentally and theoretically. The experiments were carried out over the temperature range 295-800 K and the pressure range 20-200 Torr (maintained by He or N(2)). The allyl and propargyl radicals were generated by the pulsed laser photolysis of respective precursors, 1,5-hexadiene and propargyl chloride, and were probed by using a cavity ring-down spectroscopy technique. The temperature-dependent absorption cross sections of the radicals were measured relative to that of the HCO radical. The rate constants have been determined to be k(C(3)H(5) + C(3)H(5)) = 1.40 × 10(-8)T(-0.933) exp(-225/T) cm(3) molecule(-1) s(-1) (Δ log(10)k = ± 0.088) and k(C(3)H(5) + C(3)H(3)) = 1.71 × 10(-7)T(-1.182) exp(-255/T) cm(3) molecule(-1) s(-1) (Δ log(10)k = ± 0.069) with 2σ uncertainty limits. The potential energy surfaces for both reactions were calculated with the CBS-QB3 and CASPT2 quantum chemical methods, and the product channels have been investigated by the steady-state master equation analyses based on the Rice-Ramsperger-Kassel-Marcus theory. The results indicated that the reaction between allyl and propargyl radicals produces five-membered ring compounds in combustion conditions, while the formations of the cyclic species are unlikely in the self-reaction of allyl radicals. The temperature- and pressure-dependent rate constant expressions for the important reaction pathways are presented for kinetic modeling.     

Fourier transform microwave spectroscopy of the Rg-SH(2Pi(i)) complexes (Rg:Ne, Kr): determination of the intermolecular potential energy surfaces

Pure rotational spectra of Ne-SH and Kr-SH have been studied by Fourier transform microwave spectroscopy. R-branch transitions in the lower-spin component (Omega=3/2) corresponding to a linear (2)Pi(i) radical were observed for J(")=1.5-4.5 in the region 11-25 GHz for Ne-SH and for J(")=1.5-6.5 in the region 5-20 GHz for Kr-SH, respectively, with parity doublings and hyperfine splittings associated with the H nucleus. Although the spectral pattern of Kr-SH is relatively regular, that of Ne-SH is irregular with the J dependence of the parity doublings quite different from other Rg-SH or Ar-OH complexes. Two-dimensional intermolecular potential energy surfaces (IPSs) for both of the species have been determined from the least-squares fittings of the observed rotational transitions utilizing results of high-level ab initio calculations. These IPSs reproduce the observed transition frequencies within the experimental error and provide accurate knowledge on the intermolecular interaction and internal dynamics. Systematic comparisons of Rg-SH complexes have clarified various features of this series of complexes.     

High resolution protein separations using affinity ultrafiltration with small charged ligands

Although the feasibility of affinity ultrafiltration was demonstrated more than 20 years ago, commercial applications have not developed due to the high cost and practical limitations of the large macroligands needed for highly selective separations. The objective of this study was to examine the use of small charged affinity ligands for protein purification by exploiting electrostatic interactions between the charged complex and an electrically-charged membrane. Experiments were performed using bovine serum albumin and ovalbumin with Cibacron Blue as the affinity ligand. Negatively charged versions of a composite regenerated cellulose membrane were generated by covalent attachment of a sulfonic acid functionality. Binding experiments were used to identify appropriate conditions for protein separations. The selectivity for the separation of BSA and ovalbumin was a function of the solution conditions, Cibacron Blue concentration, and membrane charge, with the addition of Cibacron Blue causing a 30-fold increase in selectivity. A diafiltration process was performed at the optimal conditions, giving a BSA product with a purification factor of more than 90-fold and a yield greater than 90%. These results clearly demonstrate the potential of using a small charged affinity ligand for high resolution protein separations.     

Estimation of thorium intake due to consumption of vegetables by inhabitants of high background radiation area by INAA

A study was conducted to estimate the thorium concentration in locally grown vegetables in high background radiation area (HBRA) of southern coastal regions of India. Locally grown vegetables were collected from HBRA of southern coastal regions of India. Thorium concentration was quantified using instrumental neutron activation analysis. The samples were irradiated at CIRUS reactor and counted using a 40% relative efficiency HPGe detector coupled to MCA. The annual intake of thorium was evaluated using the consumption data provided by National Nutrition Monitoring Board. The daily intake of ²³²Th from the four food categories (green leafy vegetables, others vegetables, roots and tubers, and fruits) ranged between 0.27 and 5.352?mBq?d^?1. The annual internal dose due to ingestion of thorium from these food categories was 46.8?×?10^?8 for female and 58.6?×?10^?8?Sv?y^?1 for male.     

Phytochemical screening and anti-inflammatory actions of Alangium salviifolium root extract

Alangium salviifolium root was screened for phytochemical and anti-inflammatory properties. The percentage inhibition of carrageenan induced paw oedema was studied in rats. Alangium salvifolium gave maximum extractive values with Ethanol and the Loss on Drying value, total ash value and acid-insoluble ash and water soluble ash values were within limits. The extract gave positive tests for phytosterols, triterpenes, flavonoids, carbohydrates and alkaloids. The extract was free from glycosides, saponins, tannins, proteins and amino acids. In acute toxicity studies, Alangium salviifolium root extract was found to be safe up to 3000?mg?kg?1, p.o. in the albino rats. The Alangium salviifolium root gave significant per cent inhibition of the maximal paw oedema and very highly significant per cent inhibition of total paw oedema during 6?h. This study revealed that Alangium salviifolium root has good anti-inflammatory actions when compared with Diclofenac sodium.