Si passivation for Ge pMOSFETs: Impact of Si cap growth conditions

Ultra thin Si cap growth by Reduced Pressure Chemical Vapor Deposition on relaxed Ge substrates is detailed in this paper for Ge pMOSFET (Metal Oxide Semiconductor Field Effect Transistors) passivation purposes. A cross calibration of different measurement techniques is first proposed to perfectly monitor Si monolayers thickness deposited on Ge substrates. Different characteristics, impacting Ge pMOSFETs device performances, are next detailed for various Si cap growth processes using different Si precursors: DiChloroSilane (DCS), silane and trisilane. The critical Si thickness of plastic relaxation has been determined at 12 monolayers. Presence of point defects has been identified for very low growth temperature as 350 °C. Ge-Si intermixing, caused by a Ge segregation mechanism, is strongly reduced by the use of trisilane as Si precursor at low temperatures.     

Highly efficient coupling of photons from nanoemitters into single-mode optical fibers

Highly efficient coupling of photons from nanoemitters into single-mode optical fibers is demonstrated using tapered fibers. A percentage (7.4 ± 1.2%) of the total emitted photons from single CdSe/ZnS nanocrystals were coupled into a 300 nm diameter tapered fiber. The dependence of the coupling efficiency on the taper diameter was investigated and the coupling efficiency was found to increase exponentially with decreasing diameter. This method is very promising for nanoparticle sensing and single-photon sources.     

4‐kV 100‐Mbps monolithic isolator on SOI with trench isolation for wideband networks

Two types of monolithic isolator on a silicon‐on‐insulator (SOI) with trench isolation have been fabricated. One is a multitrench isolator with polysilicon resistors in which two circuit areas are isolated using thirty‐four 0.4‐µm‐wide trenches on an SOI. The inequality in the voltages applied to the trenches is reduced by using polysilicon resistors parallel to the trenches, which increases the isolation voltage from 2.6 to 4.0 kV. The other is a spiral wide‐trench isolator in which two circuit areas are isolated using two spiral 10‐µm‐wide trenches. Monocrystalline silicon is used as a resistor to reduce the inequality in the trench voltages. Signals are transmitted between the two circuit areas through two series of high‐voltage capacitors: silicon on buried oxide and a third metal are used as electrodes. A network interface large‐scale integration (LSI) with a four‐channel isolator was fabricated using multitrench isolation. It provides 4‐kV isolation and supports 100‐Mbps transmission. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Mast Cells Are Activated in the Giant Earlobe Keloids: A Case Series

Mast cells and inflammatory cells are abundant in keloid and hypertrophic scar tissues. Even if the cause of physical injury is similar, such as piercing or scratching with hands, clinical findings show differences in the size of keloids in the same area. Hence, we performed histological studies on giant keloids larger than the earlobe, and other smaller keloids. We also examined the risk factors associated with the formation of giant lesions. No statistically significant differences in the association of the risk factors were observed. However, histological observations clearly showed a high number of degranulated or active mast cells with a trend towards a greater number of degranulated mast cells in the giant keloid tissues. Collagen production also tended to increase. Two patients with giant keloids were severely obese, suggesting that the persistent inflammatory state of obesity may also be involved in the growth of keloid lesions.     

Internal curing of Class-F fly-ash concrete using high-volume roof-tile waste aggregate

The aim of this study was to investigate the effect of a high volume of roof-tile waste coarse aggregate (5–13 mm) as an internal curing agent on the compressive strength, modulus of elasticity, pore structure, and hydration and pozzolanic reactions in paste of fly-ash concrete with a low water-to-binder ratio of 0.30. The fly-ash concrete specimens in which the replacement ratio of cement by Class-F fly ash was 40% by mass and that of normal coarse aggregate by roof-tile waste aggregate was 40% by volume, were cured up to 728 days. Internal curing with roof-tile waste aggregate increased the compressive strength of the fly-ash concrete by 8.4–16.5% and decreased the modulus of elasticity by 4.9–12.8%. The use of a high volume of waste aggregate decreased the volume of the capillary pores in the 0.01–10 µm range and the volume proportion of the 0.02–0.33-µm pores after 28 days, but increased the volume proportion of 0.003–0.02-µm pores slightly at 7 days and significantly up to 728 days, and the consumption of Ca(OH)₂ in the fly-ash concrete. This roof-tile waste aggregate can be used as an internal water reservoir to increase the compressive strength and to improve the pore structure of concrete with a high-volume (40%) replacement of Class-F fly ash.     

Mechanical Strength and Failure Characteristics of Cast Mg-9 pctAl-1 pctZn Alloys Produced by a Heated-Mold Continuous Casting Process: Tensile Properties

The mechanical properties and failure characteristics of a cast Mg alloy (AZ91: Mg-Al_8.9-Zn_0.6-Mn_0.2) produced by a heated-mold continuous casting process (HMC) are investigated. In a modification of the original HMC process, the cooling of the liquid alloy by direct water spray is carried out in an atmosphere of high-purity argon gas. The HMC-AZ91 alloy exhibits excellent mechanical properties (high strength and high ductility) that are about twice as high as those for the same alloy produced by conventional gravity casting. The increased material strength and ductility of the HMC sample are attributed to nanoscale and microscale microstructural characteristics. The fine grains and tiny spherical eutectic structures (e.g., Mg₁₇Al₁₂ and Al₆Mn) distributed randomly in the matrix of the HMC alloy result in resistance to dislocation movement, leading to high tensile strength. Basal slip on (0001) planes in the relatively organized crystal orientation of the HMC alloy, as well as grain boundary sliding through tiny spherical eutectic structures, results in high ductility. Details of the failure mechanism under static loading in the HMC alloy are also discussed using failure models.     

Coalesced C60 Molecules in Toluene Under Ultrahigh Pressure

Abstract

We present mass spectral evidence that coalesced C60 dimers and trimers were formed in toluene under 1.2-1.4 GPa at room temperature.     

Racial discrimination and psychological distress: The impact of ethnic identity and age among immigrant and United States-born Asian adults.

The association between racial and ethnic discrimination and psychological distress was examined among 2,047 Asians (18 to 75 years of age) in the National Latino and Asian American Study, the first-ever nationally representative study of mental health among Asians living in the United States. Stratifying the sample by age in years (i.e., 18 to 30, 31 to 40, 41 to 50, 51 to 75) and nativity status (i.e., immigrant vs. U.S.-born), ethnic identity was tested as either a protective or exacerbating factor. Analyses showed that ethnic identity buffered the association between discrimination and mental health for U.S.-born individuals 41 to 50 years of age. For U.S.-born individuals 31 to 40 years of age and 51 to 75 years of age, ethnic identity exacerbated the negative effects of discrimination on mental health. The importance of age and immigrant status for the association between ethnic identity, discrimination, and well-being among Asians in the United States is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Radiological evidence of involvement of dust exposure in pathogenesis of pulmonary alveolar proteinosis

A 52-year-old man was admitted because of increasing dyspnea on exersion and presence of pulmonary infiltrates. The patient had pulmonary tuberculosis at the age of 31, which resulted in volume loss and calcified foci in the upper lobe of his left lung. As a construction worker for more than 20 years, he had been exposed to inorganic dusts. Chest radiographs showed a symmetrical consolidation of infiltrates in both lungs with the exception of the left upper lobe, where no apparent infiltrates were shown. A computed tomographic scan of the chest revealed widely panlobular consolidation with the exception of the left upper lobe. A diagnosis of pulmonary alveolar proteinosis (PAP) was established by analysis of bronchoalveolar lavage fluid. Although the patient underwent segmental bronchoalveolar lavage four times under general anesthesia, he suffered frequent pulmonary infection and died two years after the onset his symptoms. Interestingly, the patient had a markedly narrowed orifice in the left upper lobe, as demonstrated by fiberoptic bronchoscopy. Chest radiographs of this lung field revealed no infiltrative shadows. These results suggest that some inhalative agent was involved in the pathogenesis of PAP in this case. In addition, significantly increased levels of KL-6 detected in both serum and bronchoalveolar lavage fluid were attributable to overproduction of KL-6 by Type II pneumocytes that had been stimulated or damaged by PAP.