Convenient photooxidation of alcohols using dye sensitised semiconductors in combination with silver nitrate and TEMPO--an electron paramagnetic resonance study

A mechanistic investigation into the photooxidation of alcohols using dye sensitised titanium dioxide and dye sensitised zinc oxide is described. The varying yields using the two photocatalysts have been explained using electron paramagnetic resonance (EPR) spectroscopy, which indicated that electron injection occurs in the dye sensitised ZnO system but is sluggish in the dye sensitised TiO(2) system. Due to the failure of the electron injection step, a 'break' in the photooxidative system occurs resulting in a decrease in the conversion of benzyl alcohol to benzaldehyde for the dye sensitised TiO(2) system.     

Colour emission tunability in Ho3+–Tm3+–Yb3+ co-doped Y2O3 upconverted phosphor

The frequency upconversion (UC) emission throughout the visible region from the Y₂O₃:Ho³⁺?CTm³⁺?CYb³⁺ co-doped phosphors synthesized by using low temperature combustion process upon excitation with a diode laser operating at 980?nm have been presented. The colour emission tunability in co-doped phosphor has been observed on increasing the pump power and seen by the naked eyes. The tunability in colour emission has also been visualized by CIE chromaticity diagram. The variation in UC emission intensity of the ¹G₄????³H₆ (Tm³⁺) and ⁵F₃????⁵I₈ (Ho³⁺) transitions lying in the blue region has been monitored with increase in the pump power and marked that their ratio can be used to determine the temperature. The developed phosphor has been used to record fingerprints. The observed most intense visible colour emission from the developed material may be used for photodynamic therapy and as an alternative of traditional fluorescent biolabels.     

Metabolism of the colonic mucosa in patients with inflammatory bowel diseases: an in vitro proton magnetic resonance spectroscopy study

Metabolism of the colonic mucosa of patients with ulcerative colitis (UC; n=31) and Crohn's disease (CD; n=26) and normal mucosa (control, n=26) was investigated using in vitro high-resolution proton magnetic resonance spectroscopy. Of the 31 UC patients, 20 were in the active phase and 11 were in the remission phase of the disease. Out of 26 CD patients, 20 were in the active phase, while 6 were in the remission phase of the disease. Twenty-nine metabolites were assigned unambiguously in the perchloric acid extract of colonic mucosa. In the active phase of UC and CD, significantly lower (P相似文献   

Two-photon absorption in TeO2-PbO glasses excited at 532 and 590 nm

Degenerate two-photon absorption (TPA) in a binary glass with composition TeO₂-PbO is reported. The TPA coefficient, α₂, obtained with nanosecond laser pulses at 532 and 590 nm, increases when the relative amount of PbO is increased. The maximum TPA coefficient, α₂= 12.6 cm/GW, is comparable to or larger than the values reported for crystalline semiconductors and other recently reported glasses. PACS 42.70.-a; 42.65.-k; 42.70.Ce; 42.62.Fi     

An FPTAS for minimizing the product of two non-negative linear cost functions

We consider a quadratic programming (QP) problem (Π) of the form min x ^T C x subject to Ax ≥ b, x ≥ 0 where \({C\in {\mathbb R}^{n \times n}_+, {\rm rank}(C)=1}\) and \({A\in {\mathbb R}^{m \times n}, b\in {\mathbb R}^m}\) . We present an fully polynomial time approximation scheme (FPTAS) for this problem by reformulating the QP (Π) as a parameterized LP and “rounding” the optimal solution. Furthermore, our algorithm returns an extreme point solution of the polytope. Therefore, our results apply directly to 0–1 problems for which the convex hull of feasible integer solutions is known such as spanning tree, matchings and sub-modular flows. They also apply to problems for which the convex hull of the dominant of the feasible integer solutions is known such as s, t-shortest paths and s, t-min-cuts. For the above discrete problems, the quadratic program Π models the problem of obtaining an integer solution that minimizes the product of two linear non-negative cost functions.     

Finite-element model of interaction between fungal polysaccharide and monoclonal antibody in the capsule of Cryptococcus neoformans

Many microorganisms such as bacteria and fungi possess so-called capsules made of polysaccharides which protect these microorganisms from environmental insults and host immune defenses. The polysaccharide capsule of Cryptococcus neoformans, a human pathogenic yeast, is capable of self-assembly, composed mostly of glucuronoxylomannan (GXM), a polysaccharide with a molecular weight of approximately 2,000,000, and has several layers with different densities. The objective of this study was to model pore-hindered diffusion and binding of the GXM-specific antibody within the C. neoformans capsule. Using the finite-element method (FEM), we created a model which represents the in vivo binding of a GXM-specific antibody to a C. neoformans cell taking into account the intravenous infusion time of antibody, antibody diffusion through capsular pores, and Michaelis-Menten kinetics of antibody binding to capsular GXM. The model predicted rapid diffusion of antibody to all regions of the capsule where the pore size was greater than the Stokes diameter of the antibody. Binding occurred primarily at intermediate regions of the capsule. The GXM concentration in each capsular region was the principal determinant of the steady-state antibody-GXM complex concentration, while the forward binding rate constant influenced the rate of complex formation in each region. The concentration profiles predicted by the model closely matched experimental immunofluorescence data. Inclusion of different antibody isotypes (IgG, IgA, and IgM) into the modeling algorithm resulted in similar complex formation in the outer capsular regions, but different depths of binding at the inner regions. These results have implications for the development of new antibody-based therapies.     

Improved approximations for two-stage min-cut and shortest path problems under uncertainty

Mathematical Programming - In this paper, we study the robust and stochastic versions of the two-stage min-cut and shortest path problems introduced in Dhamdhere et al. (in How to pay, come what...     

Synthesis,characterization and evaluation of amphoteric galactomannan derivative for the mitigation of malachite green and congo red dye from aqueous solution

Cellulose - Biopolymeric materials have been utilized for water treatment since ancient times. Consequently, novel sustainable, inexpensive and natural biobased alternatives have been explored...