Localized surface plasmon resonances arising from free carriers in doped quantum dots

Localized surface plasmon resonances (LSPRs) typically arise in nanostructures of noble metals resulting in enhanced and geometrically tunable absorption and scattering resonances. LSPRs, however, are not limited to nanostructures of metals and can also be achieved in semiconductor nanocrystals with appreciable free carrier concentrations. Here, we describe well-defined LSPRs arising from p-type carriers in vacancy-doped semiconductor quantum dots (QDs). Achievement of LSPRs by free carrier doping of a semiconductor nanocrystal would allow active on-chip control of LSPR responses. Plasmonic sensing and manipulation of solid-state processes in single nanocrystals constitutes another interesting possibility. We also demonstrate that doped semiconductor QDs allow realization of LSPRs and quantum-confined excitons within the same nanostructure, opening up the possibility of strong coupling of photonic and electronic modes, with implications for light harvesting, nonlinear optics, and quantum information processing.     

Carotid-jugular arteriovenous fistula: a case report of an iatrogenic complication following internal jugular vein catheterization for hemodialysis access

We report a case of diabetic end-stage renal disease patient who presented with a right common carotid artery jugular arteriovenous fistula as a complication of the insertion of a polyurethane double-lumen hemodialysis catheter into the right internal jugular vein .On physical examination of the neck, a pulsating mass with a palpable thrill and a bruit was noted in the right subclavicular region. The diagnosis was confirmed by color doppler ultrasonography of the neck and carotid angiography. The review of the literature suggests the occurrence of this complication as rather rare. The fistula was successfully repaired surgically. It is emphasized that while securing the access, a thorough physical examination with a special emphasis on seeking any neck swellings, thrill, and bruit along with routine use of vascular doppler for securing dialysis access is recommended.     

Steam drum level dynamics in a multiple loop natural circulation system of a pressure-tube type boiling water reactor

Advanced Heavy Water Reactor (AHWR) is a pressure tube type boiling water reactor employing natural circulation as the mode of heat removal under all the operating conditions. Main heat transport system (MHTS) of AHWR is essentially a multi-loop natural circulation system with all the loops connected to each other. Each loop of MHTS has a steam drum that provides for gravity based steam–water separation. Steam drum level is a very critical parameter especially in multi-loop natural circulation systems as large departures from the set point may lead to ineffective separation of steam–water or may affect the driving head. However, such a system is susceptible to steam drum level anomalies under postulated asymmetrical operating conditions among the different quadrants of the core like feedwater flow distribution anomaly among the steam drums or power anomaly among the core quadrants. Analyses were carried out to probe such scenarios and unravel the underlying dynamics of steam drum level using system code RELAP5/Mod3.2. In addition, a scheme to obviate such problem in a passive manner without dependence on level controller was examined. It was concluded that steam drums need to be connected in the liquid as well as steam space to make the system tolerant to asymmetrical operating conditions.     

Morphology of the Tin Whiskers on the Surface of a Sn-3Ag-0.5Cu-0.5Nd Alloy

Rapid growth of tin whiskers has been observed on the surface of rosette-shaped NdSn₃ intermetallic phase in a Sn-3Ag-0.5Cu-0.5Nd alloy after air storage. It is shown that various cross sections of NdSn₃ rosettes in the solder matrix reveal different morphologies of tin whiskers, which can be classified as four types: long fibers, short fibers, tiny sprouts, and hillocks. The fibrous whiskers and tiny sprouts are found on the surfaces of specimens exposed to air at room temperature and 423 K (150 °C), while hillocks appear only after storage at 423 K (150 °C). In addition, it is observed that, in most cases, each oxidized NdSn₃ intermetallic phase contains only a single whisker at its center. Through metallographic observations and chemical analyses on the cross sections of the oxidized NdSn₃ intermetallics, a “successive compressive stress model” has been proposed to interpret the tin whisker growth on the surface of a rare earth (RE)–containing solder.     

Effects of rice harvest moisture on kernel damage and milled rice surface free fatty acid levels

ABSTRACT:  Surface free fatty acid (FFA) on milled rice is a key factor in determining rice quality and acceptability to the brewing industry. Rice FFA oxidizes, causing off-flavors and odors to develop, compromising the brewing quality of milled rice. The effect of harvest moisture (13%, 16%, and 20%), harvester type (1688 Case and 9500 John Deere), and rice variety (Cocodrie and Bengal) on harvest damaged rough rice and milled rice surface FFA after drying to 12% moisture and 6 mo rough rice storage was examined. The Case harvester produced more damaged kernels than the John Deere harvester, but this was not reflected in surface FFA development. There were no significant FFA differences in variety or harvester type. Rice harvested at a higher moisture content (20%) produced significantly greater FFA values, with a peak near 0.1%, than rice harvested at lower moisture contents (13% and 16%), which had FFA values near 0.08%. Retention of bran by damaged kernels at high harvest moisture probably was responsible for promoting surface FFA development, but if bran was lost at lower harvest moistures, surface FFA, development was limited. Harvest moisture affected milled rice FFA, although rough rice was dried to 12% immediately after harvesting.     

Green's function approach for modeling of electrostatic effects in nanoscale fully depleted double‐gate silicon‐on‐insulator metal‐oxide‐semiconductor field‐effect transistors

Exact solution of two‐dimensional (2D) Poisson's equation for fully depleted double‐gate silicon‐on‐insulator metal‐oxide‐semiconductor field‐effect transistor is derived using three‐zone Green's function solution technique. Framework consists of consideration of source–drain junction curvature. 2D potential profile obtained forms the basis for estimation of threshold voltage. Temperature dependence of front surface potential distribution, back surface potential distribution and front‐gate threshold voltage are modeled using temperature sensitive parameters. Applying newly developed model, surface potential and threshold voltage sensitivities to gate oxide thickness have been comprehensively investigated. Device simulation is performed using ATLAS 2D (SILVACO, 4701 Patrick Henry Drive, Bldg. Santa Clara, CA 95054 USA) device simulator, and the results obtained are compared with the proposed 2D model. The model results are found to be in good agreement with the simulated data. Copyright © 2013 John Wiley & Sons, Ltd.     

Efficacy of continuous wear PureVision contact lenses for therapeutic use.

PURPOSE: To evaluate the Bausch and Lomb PureVision contact lens as continuous wear contact lens for therapeutic and medical indications in a prospective open-ended non-randomized trial. METHODS: Patients who required therapeutic contact lens wear for various indications such as pain relief, corneal protection, persistent epithelial defects, corneal perforation and chemical burns were fitted with PureVision continuous wear contact lenses (balafilcon A, 36% water content). Success or failure of specific treatment indication was assessed in each case with evaluation of ocular and lens related complications. RESULTS: 30 eyes of 28 patients were fitted with PureVision continuous wear contact lenses. A successful fit was seen in 27 of 30 eyes with therapeutic success in 26 of 30 eyes. However, all patients reported symptomatic relief. Duration of lens use ranged from 3 days to 3 months. Dry eye was the most frequent cause of contact lens associated therapeutic failure. Complications included lens loss (two eyes), tight lens (one eye) and infective keratitis (two eyes). CONCLUSIONS: PureVision contact lenses were found to be safe and efficacious for continuous wear therapeutic use to a maximum of 90 days. The contact lens was also easier to handle by virtue of its resilient nature. There were no significant corneal complications of hypoxia, i.e. corneal oedema. Lens losses and deposits were minimal. The lens performance and fitting characteristics compares favorably with previous therapeutic lenses used by the investigators. This new lens may be considered as a safe and effective alternative for use as bandage contact lens.