Hydrogen production by electrochemical decomposition of formic acid via solid polymer electrolyte

The aim of this work is to investigate the feasibility of simultaneous hydrogen production by electrochemical decomposition of formic acid via solid polymer electrolyte (SPE) in an electrochemical reactor. Titanium oxide coated with iridium oxide as anode and carbon fibre with Pt catalyst as cathode were used in the experiments.     

Loneliness, Social Network Size, and Immune Response to Influenza Vaccination in College Freshmen.

Antibody response to the influenza immunization was investigated in 83 1st-semester healthy university freshmen. Elevated levels of loneliness throughout the semester and small social networks were independently associated with poorer antibody response to 1 component of the vaccine. Those with both high levels of loneliness and a small social network had the lowest antibody response. Loneliness was also associated with greater psychological stress and negative affect, less positive affect, poorer sleep efficiency and quality, and elevations in circulating levels of cortisol. However, only the stress data were consistent with mediation of the loneliness-antibody response relation. None of these variables were associated with social network size, and hence none were potential mediators of the relation between network size and immunization response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of molding conditions on the shrinkage and roundness of injection molded parts

During the plastic injection molding process, one of the biggest challenges is shrinkage which deteriorates the quality of produced parts. To control and reduce this defect, the essential way is to perfectly determine the variables like molding parameters. In this study, the effects of molding parameters including packing pressure, melt temperature, and cooling time on shrinkage and roundness have been investigated experimentally. Also, the relationship among initial molding parameters, the cavity pressure, and mold temperature was investigated. The results of this experimental study and analysis fulfill various requirements of plastic injection molding and clarify the relationship between molding conditions and the overall quality of produced parts. This study illustrated that packing pressure and melt temperature are dominant factors which determine the quality of parts.     

Flexible pillars for displacement compensation in optical chip assembly

In chip-to-chip optical interconnect systems with surface mounted light-sources and detectors, thermal and mechanical effects can cause lateral displacements of the assembled devices. These displacements can result in optical signal losses that can critically deteriorate the bit-error-rate of the digital system. We demonstrate that, for a given loss budget of 1 dB, the use of flexible optical pillars with 150-/spl mu/m height and 50-/spl mu/m diameter can double the lateral displacement tolerance from about 15 to 30 /spl mu/m. The pillars fabricated from Avatrel polymer form an air-free path between the light source and the substrate and cause maximum optical power losses less than 0.2 dB.     

PERFORMANCE OF CODED OFDM VIA VARIABLE GUARD INTERVAL

This letter presents the principles of Coded Orthogonal Frequency Division Multiplexing (COFDM) system and focuses on the effect of the Guard Interval (GI) on the system performance. The role of the GI parameter period to solve the problem of interferences that occur at the receiver is discussed. A new COFDM concept with a Variable GI (VGI) is proposed in order to improve the Bit Error Rate (BER) performance in the presence of multipaths with variable delays. A series of simulations have been carried out on the BER performance as a function of GI, maximum delay spread, and Signal-to-Noise Ratio (SNR), with QPSK as modulation scheme over multipath fading and Additive White Gaussian Noise (AWGN). The results show that the optimum values of the GI parameter approximately equal to the maximum delay spread, and the proposed system with VGI provides a better performance compared with the fixed length GI.     

Sea of polymer pillars electrical and optical chip I/O interconnections for gigascale integration

Optical chip-to-chip communication is a promising technology that can mitigate some of the performance short-comings of electrical interconnections, especially bandwidth. Moreover, future high-performance chips are projected to drain hundreds of amperes of supply current. To this end, it is important to develop a high-density and high-performance integrated electrical and optical chip I/O interconnection technology. We describe sea of polymer pillars (or polymer pins), which enables the simultaneous batch fabrication of electrical and optical I/O interconnections at the wafer-level. The electrical and optical I/O interconnections are designed to be laterally compliant to minimize the stresses on the die's low-k dielectric as well as to maintain optical alignment between the coefficient of thermal expansion (CTE)-mismatched board and die during thermal cycling. We demonstrate the fabrication and mechanical performance of various size and aspect ratio electrical and optical polymer pillars. We also describe methods of fabricating polymer pillars with nonflat tip surface area for optical interconnection.     

Comparative Study of Mechanical and Tribological Properties of Alumina Coatings Formed on 5754 Aluminium Alloy under Various Conditions

In this paper we present the results of the comparative study of the performance of two sulfuric and oxalic anodizing process already retained, based on the superposition of the surface responses. For this purpose two Doehlert experimental designs with three variables (temperature, current density, sulphuric acid concentration) and other three variables (temperature, current density, oxalic acid concentration) were realized. Three responses were studied, namely: growth rate, Vickers microhardness, wear rate after friction test of the anodic oxide layer. A comparative study based on the surface responses was carried out. Compared with the sulphuric acid bath, it was found that the oxalic acid bath affords low growth rates, high wear resistance and high microhardness but less ductile layers. The observed mechanical properties of the oxide layers can be related to their morphology revealed by the scanning electron microscopy and optical observations and their chemical composition determined by the glow-discharge optical emission spectroscopy.     

Heterologous Expression of an Unusual Ketosynthase,SxtA, Leads to Production of Saxitoxin Intermediates in Escherichia coli

Paralytic shellfish toxins (PSTs) are neurotoxic alkaloids produced by freshwater cyanobacteria and marine dinoflagellates. Due to their antagonism of voltage-gated sodium channels in excitable cells, certain analogues are of significant pharmacological interest. The biosynthesis of the parent compound, saxitoxin, is initiated with the formation of 4-amino-3-oxo-guanidinoheptane (ethyl ketone) by an unusual polyketide synthase-like enzyme, SxtA. We have heterologously expressed SxtA from Raphidiopsis raciborskii T3 in Escherichia coli and analysed its activity in vivo. Ethyl ketone and a truncated analogue, methyl ketone, were detected by HPLC-ESI-HRMS analysis, thus suggesting that SxtA has relaxed substrate specificity in vivo. The chemical structures of these products were further verified by tandem mass spectrometry and labelled-precursor feeding with [guanidino-¹⁵N₂] arginine and [1,2-¹³C₂] acetate. These results indicate that the reactions catalysed by SxtA could give rise to multiple PST variants, including analogues of ecological and pharmacological significance.     

Vitreitis and Waldenstr?m''s macroglobulinemia

PURPOSE: To describe vitreitis in a patient with Waldenstr?m's macroglobulinemia. METHODS: Case report and review of pertinent literature. RESULTS: A 90-year-old man developed vitreitis 10 years after a systemic diagnosis of a lymphoproliferative disorder. Numerous small, normal-appearing lymphocytes were seen on pathologic examination of the vitreous. He developed worsening lymphadenopathy and was diagnosed with Waldenstr?m's macroglobulinemia after systemic review. CONCLUSION: Chronic lymphoproliferative diseases such as Waldenstrom's macroglobulinemia may cause vitreitis.