Unexpected Formation of a Doubly Bridged Cyclo-1,2-dithian 1D Coordination Cu<Subscript>2</Subscript>I<Subscript>2</Subscript>-Containing Luminescent Polymer

Abstract  

CuI reacts instantaneously with butanedithiol in MeCN solution to form a sparingly soluble and thermally stable colorless polymeric material 1 of composition [(Cu₂I₂){HS(CH₂)₄SH}] _n . Raman and IR spectroscopy confirm the presence of Cu(I) bound S–H functions. Furthermore, small amounts of the yellow compound [{Cu(μ₂-I)₂Cu}(C₄H₈S₂)₂] _n 2 co-crystallize after several days. If the reaction mixture is exposed to air, polymeric 2 is isolated as the main product. An X-ray diffraction study reveals that 1D polymer 2 is assembled by rhomboid Cu(μ₂-I)₂Cu clusters (d Cu···Cu 2.6843(18) ?), which are linked through the S-atoms of six-membered 1,2-dithian heterocycles, thus generating an infinite ribbon. The low-frequency region in the Raman spectra show a striking similarity suggesting that polymers 1 and 2 bear the same cluster rhomboid Cu(μ₂-I)₂Cu clusters. The photophysics and luminescence properties of 2 have been studied experimentally and by means of DFT/TDDFT calculations.     

Review of Generalized anxiety disorder: From science to practice.

Reviews the book, Generalized anxiety disorder: From science to practice by Michel J. Dugas and Melisa Robichaud (2006). The reviewers commend the authors for providing a comprehensive overview of GAD. Chapters include information on diagnosis, assessment techniques and treatment modules. Dugas and Robichaud refer to their treatment as primarily cognitive and emphasize the difference between their approach and other cognitive and cognitive-behavioural treatments for GAD. The treatment presented does not employ relaxation training or other strategies to reduce physical tension and overarousal. Rather, this treatment makes use of specific cognitive interventions with the understanding that physical and affective symptoms will decrease with corresponding reductions in excessive worry. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A probable explanation for mild extra-articular manifestations in Indian patients of rheumatoid arthritis: a preliminary study

The combination of a total lower lip, chin, and anterior mandibular defect following cancer resection is an extremely complex problem that requires a sequence of operations to optimize functional and aesthetic results. One patient is presented in whom the defect was reconstructed with a free fibular flap followed by a series of ancillary procedures using both modern and traditional techniques. At the time of tumor ablation, the through-and-through oromandibular defect was reconstructed with a fibular osteocutaneous flap. The lower lip and gingivolabial sulcus was reconstructed later with a tongue flap. Tissue expansion was subsequently used to replace the fibular skin with expanded submental hair-bearing skin. A polyethylene implant was added later to the fibular bone for chin augmentation. Subsequently the lower lip was supported with a tendinous graft suspended to the anterior masseter bilaterally. Lastly, the vermilion border was elevated by removing a rim of the tongue flap and covering the secondary wound with a full-thickness skin graft. At the end of the reconstructive procedures, lip seal and oral aperture were good with no drooling and excellent speech.     

Noninvasive measurement of the pH of the endoplasmic reticulum at rest and during calcium release

The pH within individual organelles of the secretory pathway is believed to be an important determinant of their biosynthetic activity. However, little is known about the determinants and regulation of the pH in the secretory organelles, which cannot be readily accessed by [H+]-sensitive probes. We devised a procedure for the dynamic, noninvasive measurement of pH in the lumen of the endoplasmic reticulum in intact mammalian cells. A recombinant form of the B subunit of Shiga toxin, previously modified to include a carboxyl-terminal KDEL sequence and a pH-sensitive fluorophore, was used for a two-stage delivery strategy. Retrograde traffic of endogenous lipids was harnessed to target this protein to the Golgi complex, followed by retrieval to the endoplasmic reticulum (ER) by KDEL receptors. Immunofluorescence and immunoelectron microscopy were used to verify the subcellular localization of the modified B fragment. Fluorescence ratio imaging and two independent calibration procedures were applied to determine the pH of the ER in situ. We found that the pH of the endoplasmic reticulum is near neutral and is unaffected during agonist-induced release of calcium. The ER was found to be highly permeable to H+ (equivalents), so that the prevailing [H+] is susceptible to alterations in the cytosolic pH. Plasmalemmal acid-base transporters were shown to indirectly regulate the endoplasmic reticulum pH.     

HLA class-I and class-II antigen association in rheumatoid arthritis at Varanasi, India

We examined the localization of phosphotyrosine (p-Tyr)-modified proteins in the normal corneal epithelium using affinity-purified rabbit anti-p-Tyr antibody. Normal rat cornea was fixed and semi-thin and ultra-thin frozen sections were prepared. Immunofluorescence microscopy showed that p-Tyr was distributed along the cell membrane of the corneal epithelium. Immunogold electron microscopy revealed that the labeling is exclusively localized in the desmosomes and hemidesmosomes. A fraction enriched with desmosomes was extracted from the bovine corneal epithelium and examined by Western blotting. Immunoblotting for p-Tyr showed eight prominent bands (290, 200, 190, 115, 85, 62, 50, and 47 kD) in the desmosomal fraction. The enrichment of p-Tyr in desmosomes and hemidesmosomes of the corneal epithelium suggests that these cell-to-cell and cell-to-substrate junctions are involved in signal transduction.     

Effect of the impact angle on the breakage of agglomerates: a numerical study using DEM

The study of agglomerate strength is of vital importance in several industrial applications such as pharmaceutical, detergent and food manufacturing. Agglomerates could experience a size reduction during the production and handling processes due to collisions with other agglomerates or with the moving components and walls as well as during bulk flow due to shear deformation. In this analysis, we focus on the agglomerate damage due to oblique impact on walls, as this is a common damage process during, for example, pneumatic conveying and size reduction in pin mills.

Computer simulations have been carried out using Distinct Element Analysis, where the breakage characteristics of oblique impacts and the effect of the interparticle bond strength have been analysed. The procedure adopted here provides an isotropic and spherical agglomerate (uniform mass distribution and coordination number within radial segments of the agglomerate). The results indicate that the damage ratio (i.e. the number fraction of the broken bonds) depends on the normal component of the impact velocity only, i.e. the tangential component has little effect. However, the position of the clusters produced on impact does depend on the impact angle, which influences the pattern of breakage and in turn the size distribution of the large clusters.     

Design for Six Sigma

The concept of implementation of Six Sigma methodology was pioneered at Motorola in the 1980s with the aim of reducing quality costs. Six Sigma methodology has evolved into a statistically oriented approach to process, product or service quality improvement. It is a business performance improvement strategy used to improve profitability, to drive out waste in business processes and to improve the efficiency of all operations that meet or exceed customers' needs and expectations. A performance level of Six Sigma equates to 3-4 defects per million opportunities, where sigma is a statistical measure of the amount of variation around the process average. The average sigma level for most companies is three sigma. The authors offer guidance as to how companies may achieve Six Sigma performance. Organisations that have adopted the principles and concepts of Six Sigma methodology have realised that once they have achieved Five Sigma quality levels the only way to surpass the Five Sigma quality level is to redesign their products, processes and services from scratch. These circumstances have led to the development of what we call today 'design for Six Sigma'. Design for Six Sigma is a powerful approach to designing products, processes and services in a cost-effective and simple manner, to meet the needs and expectations of the customer     

Processes for production of high-purity metal powders

Production of high-quality metal powders is becoming important to meet the increasing demand for manufacturing advanced materials. A number of standard powder production techniques have been developed to meet the increasing demand for high-purity metal powders. This paper discusses the different techniques of producing metal powder.     

A Novel Synthesis,Structural, Morphological,and Opto-magnetic Characterizations of Magnetically Separable Spinel Co x Mn1−x Fe2O4 (0 ≤ x ≤ 1) Nano-catalysts

Spinel Co _x Mn_1?x Fe₂O₄ (0≤x≤1) nano- crystals were successfully synthesized by a simple microwave-assisted combustion method. High-resolution scanning electron microscopy (HR-SEM) and transmission electron microscopy (HR-TEM) analysis was used to study the morphological variations and found the particle-like nanocrystal morphologies. Energy dispersive X-ray (EDX) results showed that the composition of the elements were relevant as expected from the combustion synthesis. Powder X-ray diffraction (XRD) analysis showed that all composition was found to have cubic spinel-type structure. Average crystallite size of the samples was found to be in the range of 10.36–21.16 nm. The lattice parameter decreased from 8.478 to 8.432 Å with increasing Co²⁺ content. Fourier transform infrared (FT-IR) spectra showed two strong absorption peaks observed at lower frequency (～435 to ～800 cm^?1), which can be assigned to the M–O (Mn, Co, and Fe) bonds. UV-Visible diffuse reflectance spectroscopy (DRS) shows that the energy band gap of pure MnFe₂O₄ is 1.78 eV and with increase in the Co²⁺ ion, it increases from 1.87 to 2.33 eV. Addition of Co²⁺ in MnFe₂O₄ reduces the particle size, which can be confirmed by the blue shift in the photoluminescence (PL) spectra. Vibrating sample magnetometer (VSM) results that confirmed a weak ferromagnetic behavior for all composition with saturation magnetization values in the range of 50.05 ±04 to 67.09 °03 emu/g. All composition of spinel Co _x Mn_1?x Fe₂O₄ nano-crystals were successfully tested as catalyst for the oxidation of benzyl alcohol to benzaldehyde, which has resulted 87.32 and 94.28 % conversion efficiency of MnFe₂O₄ and Co_0.6Mn_0.4Fe₂O₄, respectively.     

Heat capacity and thermal expansion of samarium titanate

Samarium titanate (Sm₂TiO₅) was prepared by solid-state synthesis and characterized by X-ray diffraction (XRD). Heat capacity measurements were carried out by differential scanning calorimeter (DSC) in the temperature range 298-800 K. Thermal expansion characteristics have been studied by high temperature X-ray diffraction technique (HTXRD) in the temperature range 298-1573 K. The heat capacity value at 298 K is 170 J K^− 1 mol^− 1. The percentage linear thermal expansion in the temperature range 298-1573 K along a, b and c axes are 0.96, 0.89 and 1.07 respectively. The average coefficient of thermal expansion value obtained in the present study for samarium titanate up to 1573 K is 10.8 × 10^− 6 K^− 1.