Hardness and Fracture Toughness of Solid Solutions of Mg2Si and Mg2Sn

Semiconductors - Thermoelectric material development typically aims at maximizing produced electrical power and efficiency of energy conversion, even though sometimes, this means adding expensive...     

Brown tumors in dialyzed patients with secondary hyperparathyroidism: Report of 16 cases

Brown tumors (BTs) are relatively uncommon but they are serious complications of renal osteodystrophy. The objective of this study was to analyze the clinical, biological, and radiological characteristics of 16 patients with BTs provoked by secondary hyperparathyroidism (sHPT) and its response to the decrease in parathyroid hormone levels after parathyroidectomy (PTX). The management of that uncommon condition was also reviewed. We conducted a retrospective study including 16 end‐stage renal disease patients who underwent subtotal PTX between 1997 and 2007 for severe sHPT with BTs. Our study included 10 men and 6 women, whose average age was 34 years. All patients were on dialysis. Ten of them were on dialysis for more than 5 years. The median duration on dialysis was 84 months. Patients included suffered from swellings associated with functional limitations. BTs had multiple locations in 7 patients. Jaw was the most frequent location (62%). Radiography and tomodensitometry demonstrated a mixed radio lucent and radio‐opaque lesions with an expansion of the cortical bone. Bone scan demonstrated an increased uptake of lesions. Chirurgical treatment was indicated in all cases because of severe refractory sHPT with functional limitations and/or disfiguring deformities. In all cases, BTs stopped its progression and even decreased in size. However, it was insufficient in four cases, which required a surgical resection. PTX remains an efficacious approach in resistant cases of sHPT with persistent BTs.     

A method for the chemical anchoring of carbon nanotubes onto carbon fibre and its impact on the strength of carbon fibre composites

This article proposes an alternative way to use carbon nanotubes to improve the performance of carbon fibre-reinforced composites. A chemical process, based on esterification of surface groups, is used to anchor nanotubes onto carbon fibre surface. Anchored nanotubes form a network surrounding the carbon fibres. After CNT anchoring, the tow is impregnated with an epoxy resin and tensile tests are performed on this minicomposite sample. By enhancing matrix properties and fibre/matrix interface, the CNT network has a significant influence on the composite strength.     

F-TRIA01: A Fast Bipolar Transimpedance Amplifier

This paper describes a new transimpedance amplifier for fast current pulses delivered by high energy particle detectors. The choice of a bipolar technology allowed a 100 low input impedance and a rise time down to 1 nS. The fully differential current mode architecture provides an excellent linearity and a large versatility as for its transimpedance, bandwidth and power consumption.     

A theoretical investigation on the properties of the new poly(N‐vinylcarbazole)‐3‐methylthiophene (PVK‐3MeT) synthesized graft copolymer

In this article, we present quantum chemical calculations, based on density functional theory (DFT), performed to investigate the geometries and the opto‐electronic properties of a new synthesized graft copolymer based on poly(N‐vinylcarbazole) (PVK) and poly(3‐methylthiophene) (PMeT) named PVK‐3MeT. First, we have theoretically computed and compared the structural, optical, and vibrational parameters of both neutral and doped states. In addition, the excited state was theoretically obtained by the ab initio RCIS/STO‐3G method. To assign the absorption and emission peaks observed experimentally, we computed the energies of the lowest singlet excited state with the time‐dependent density functional theory (TD‐DFT) method. Electronic parameters such as the HOMO‐LUMO band gap, the ionization potential (IP), and electron affinity (EA) are extracted. Calculations show that the PVK‐3MeT copolymer is nonplanar in its ground neutral state. Meanwhile, upon doping or photoexcitation, an enhancement of the planarity is observed, resulting on a decrease of the inter‐ring torsion angle between 3‐methylthiophene units. Such modifications in the geometric parameters induce a dramatic change on the HOMO and LUMO orbitals in the doped or excited states. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Modification of Fatty Acid,Essential Oil and Phenolic Contents of Salt‐Treated Sweet Marjoram (Origanum majorana L.) According to Developmental Stage

Abstract: Variation in the composition of Origanum majorana L. essential oil (EO) and fatty acids were studied under salt treatment. Plant material has been harvested at 2 phenological stages: early vegetative stage (EVS) and late vegetative stage (LVS) or prefloral. Our results showed that the application of 75 mM NaCl increased total lipid contents in marjoram shoots and caused great qualitative changes in the fatty acids profiles. NaCl treatment reduced and stimulated the EO yields, respectively, at EVS and LVS and induced quantitative changes in the chemical EO composition in shoots. Phenolic contents were higher during the LVS than EVS in the absence and the presence of salt. Under control conditions, RP‐HPLC analysis of the methanolic extract of marjoram dried shoots showed a predominance of flavonoid during the EVS whereas phenolic acids predominated during the LVS. However, under 75 mM NaCl, we noted a predominance of flavonoid at LVS and constant levels of phenolic and flavonoid classes at the EVS. For control treatment and at both EVS and LVS, the main components identified were respectively rosmarinic acid gallic as phenolic acids and amentoflavone as flavonoid. In the presence of salt and at the EVS, we observed a significant increase in trans‐2 hydrocinnamic, gallic acid and quercetin‐3‐galactoside contents. However, for the LVS, salt induced a stimulation of gallic acid, apigenin, and amentoflavone. Our results showed that LVS had the highest contents of bioactive compounds, and could be considered as the best stage for harvesting marjoram plants. Practical Application: In this study, the fatty acid composition, essential oil, and phenolic content of Origanum majorana were investigated. This is important for potential application of marjoram as functional food at the late vegetative stage. The richness of O. majorana in volatile and phenolic active compounds known for their antioxidant, antimicrobial, and insecticidal activities could support the utilization of this plant in a large field of application including cosmetic, pharmaceutical, agro alimentary, and biological defense.     

Photoluminescence properties of new poly(N-vinylcarbazole)-3-methylthiophene (PVK-3MeT) graft copolymer

Steady-state and time-resolved photoluminescence (TRPL) measurements are used in order to investigate the emission properties of new graft copolymer involving poly(N-vinylcarbazole) (PVK) and poly(3-methylthiophene) (PMeT) named PVK-3MeT. The photo-generated species in PVK-3MeT are identified as singlet intrachain excitons. Furthermore, radiative and nonradiative lifetimes have been calculated. The observed changes in the photo-physical properties of the different condensed phases could be directly related to the nanostructure of the material. The use of PVK in the chemical synthesis allows the obtaining of a new organic material with better emission and slowly radiative recombination compared to those of polythiophenes indicating that the radiative channel is more enhanced. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

A novel fully integrated device dedicated to ECG signal measurement

This paper describes two novel fully integrated circuits implemented in standard 0.35 μm CMOS technology dedicated to ECG signal measurement. Many specific problems related to this kind of signal are discussed. Pertinent solutions, such as high pass filtering, offset cancellation, common mode rejection, low pass filtering and capacitive coupling between different stages are proposed.     

Thin films of insoluble copolymer derived from poly(phenylene‐vinylene) obtained by thermal evaporation under vacuum

A new copolymer, referred to as poly(phenylene‐vinylene) (PPV)‐ether, built as PPV a polymer with some (? CH?CH? ) links changed into (? CH₂? O? CH₂? ) ethylic‐ether links, is insoluble in common solvents. PPV‐ether films are deposited by the thermal evaporation technique. X‐ray photoelectron spectroscopy for chemical analysis measurements indicate that the surface contamination decrease in the case of vacuum‐evaporated PPV‐ether. The scanning electron micrographs indicate that the surface of these vacuum‐deposited PPV‐ether are uniform. By comparison to the reference powder, the modification of the properties of the evaporated PPV‐ether are related to the decrease of the chain length and surface contamination. The results of the photoluminescence measurements reveal a shifting of the luminescence to blue in the vacuum‐evaporated PPV‐ether. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3091–3099, 2003