Hole mobility enhancement in strained-Si p-MOSFETs under high vertical field

The growth of a high quality, step-graded lattice-relaxed SiGe buffer layer on a Si(100) substrate is investigated. p-MOSFETs were fabricated on strained-Si grown on top of the above layer. Carrier confinement at the type-II strained-Si/SiGe buffer interface is observed clearly from the device transconductance and C-V measurements. At high vertical field, compared to bulk silicon, the channel mobility of the strained-Si device with x=0.18 is found to be about 40% and 200% higher at 300 K and 77 K respectively. Measurements on transconductance enhancement are also reported. Data at 77 K provide evidence of two channels and a large enhancement of mobility at high transverse field.     

Synthesis of Nanocrystalline FeS2 with Increased Band Gap for Solar Energy Harvesting

In this paper,we have reported the synthesis of FeS2 of higher band gap energy（2.75 eV） by using capping reagent and its successive application in organic-inorganic based hybrid solar cells.Hydrothermal route was adopted for preparing iron pyrite（FeS2） nanoparticles with capping reagent PEG-400.The quality of synthesized FeS2 material was confirmed by X-ray diffraction,field emission scanning electron microscopy,transmission electron microscopy,Fourier transform infrared,thermogravimetric analyzer,and Raman study.The optical band gap energy and electro-chemical band gap energy of the synthesized FeS2 were investigated by UV-vis spectrophotometry and cyclic voltammetry.Finally band gap engineered FeS2 has been successfully used in conjunction with conjugated polymer MEHPPV for harvesting solar energy.The energy conversion efficiency was obtained as 0.064%with a fill-factor of 0.52.     

Modeling of transient natural convection heat transfer in electric ovens

Prediction of transient natural convection heat transfer in vented enclosures has multiple applications such as understanding of cooking environment in ovens and heat sink performance in electronic packaging industry. The thermal field within an oven has significant impact on quality of cooked food and reliable predictions are important for robust design and performance evaluation of an oven. The CFD modeling of electric oven involves three-dimensional, unsteady, natural convective flow-thermal field coupled with radiative heat transfer. However, numerical solution of natural convection in enclosures with openings at top and bottom (ovens) can often lead to non-physical solutions such as reverse flow at the top vent, partly a function of initialization and sometimes dependent on boundary conditions. In this paper, development of a physics based robust CFD methodology is discussed. This model has been developed with rigorous experimental support and transient validation of this model with experiments show less than 3% discrepancy for a bake cycle. There is greater challenge in simulating a broil cycle, where the fluid inside the cavity is stably stratified and is also highlighted. A comparative analyses of bake and broil cycle thermal fields inside the oven are also presented.     

Interaction of chitosan capped ZnO nanorods with Escherichia coli

ZnO nanorods of around 80 nm length and 30–60 nm diameter, encapsulated in chitosan were synthesized through co-precipitation technique and was characterized by XRD, UV–VIS, SEM, HRTEM, AFM and FTIR. The aim of the study was to investigate the attachment of chitosan capped zinc oxide nanoparticles (ZnO NP) with Escherichia coli bacterial outermost cell membrane and their mode of action against these bacteria. The detailed characterization studies were carried out to develop insight into the process of influence of these nanostructures on bacterial cells. Antibiotic characteristics of chitosan capped ZnO nanoparticles have been compared with Amoxicillin by zone of inhibition through cup plate method.     

Synthesis and characterization of niobium doped hexagonal tungsten bronze in the systems,Cs<Subscript>x</Subscript>Nb<Subscript>y</Subscript>W<Subscript>1−y</Subscript>O<Subscript>3</Subscript>

Samples of nominal compositions, Cs_0.25Nb _y W_1−y O₃ and Cs_0.3Nb _y W_1−y O₃ with 0.0 ≤ y ≤ 0.25 and 0.0 ≤ y ≤ 0.3 were synthesized using appropriate amounts of Cs₂WO₄, WO₃ and WO₂ in evacuated and closed silica glass tubes at 800 °C. The polycrystalline products contain hexagonal shaped crystals of up to 15 μm diameter as long as y ≤ 0.15. X-ray powder patterns of the samples reveal the formation of hexagonal tungsten bronze (HTB-I) type phase with y < 0.1. A mixture of HTB-I and an analogous less reduced hexagonal tungsten bronze (HTB-II) type phase is seen when y ≥ 0.1. HTB-II content increases with increasing y, revealing close similarity to bronzoid type phases when y = x. Results of SEM/EDX analysis also support a partial substitution of tungsten by niobium in the HTB-I type phase. Infrared absorption and optical reflectivity data shows the effect of increasing amount of non-metallic phase for y > 0.1 and the effect of counterdoping by Nb⁵⁺/W⁵⁺ substitution in the metallic HTB-I type phase for y ≤ 0.1, respectively. Reinvestigations in the system Rb_0.3Nb _y W_1−y O₃ (0.0 ≤ y ≤ 0.175) show similar results with increasing content of HTB-II type phase related with y.     

Field Trials of Low-cost Reactive Media for the Passive Treatment of Circum-neutral Metal Mine Drainage in Mid-Wales,UK

This paper addresses the ability of five low-cost reactive materials to remove Zn, Pb, and Cd from Fe-poor, circum-neutral pH metal mine water in Mid-Wales, UK. Compost, fly ash, waste shell material, iron ochre, and a mixture of blast furnace slag (BFS) and basic oxygen furnace slag (BOS) were used in a series of small-scale passive treatment cells to assess metal removal from mine drainage initially containing, on average, 23.5 mg/L Zn, 0.5 mg/L Pb, and 0.05 mg/L Cd. Trial treatment cells contained between 1.5 and 12 kg of reactive media, had a 15 min residence time, and treated a discharge of up to 1 L per minute. Fly ash from a peat-fired power station was found to be the most effective material for metal removal, with concentrations reduced to 0.02 mg/L Zn, 0.0069 mg/L Pb, and 0.0001 mg/L Cd from over 1,000 L of water (between 98.6 and 99.9% removal). The other materials initially achieved high levels of metal removal (between 75 and 99.9% Zn, Pb, and Cd removed); however, all of the materials were saturated with Zn after less than 200 L of water had been treated. Metal sorption ranged from 21.4 mg/g Zn for the peat fly ash to 0.0015 mg/g Cd for the compost and BOS/BFS slag. The results of the pilot-scale field trials can be scaled to demonstrate that a modest-sized fly ash treatment cell (2.6 × 2.6 × 1 m) in size would be sufficient to remove 90% of the total metal load (Pb, Zn, and Cd) from this 10 L/min mine water discharge for a 1 year period. Importantly this research demonstrates that passive treatment for metal mine drainage can comply with water quality directives but cannot be considered a ‘walk-away’ solution; it requires modest (potentially annual) maintenance.     

Fine needle aspiration biopsy of extramedullary leukemia

OBJECTIVE: To study the cytologic features and role of fine needle aspiration biopsy (FNAB) in the diagnosis of extramedullary leukemia. STUDY DESIGN: Forty-one cases of extramedullary leukemia diagnosed by FNAB were analyzed along with their detailed clinical and hematologic features. RESULTS: Common sites of leukemic involvement were lymph nodes (34), skin (4), orbit (1), eyelid (1) and breast (1). The most common variety of leukemia was chronic myeloid in the chronic phase (17). Twenty-six patients were referred to the cytology clinic for FNAB as the initial screening test. In the majority of fresh cases, leukemia was not the first possibility considered, and FNAB played an important diagnostic role. No gross discrepancy was noted in any of the cases. CONCLUSION: FNAB is helpful in the diagnosis of extramedullary involvement by leukemia because of the good morphologic detail of blasts and other granulocytic cells. However, for more accurate subclassification of a hematologic disorder, other hematologic investigations are mandatory.     

A risk of developing multiple sclerosis following an outbreak of optic neuritis during a mean follow-up of 4.5 years

OBJECTIVE: The current study was designed to determine the risk of developing clinically definite multiple sclerosis (CDMS) after an isolated idiopathic optic neuritis (ON). PATIENTS AND METHODS: We retrospectively studied 28 patients (range from 18-45 years) who presented a unilateral acute ON between 1 st April and 31 st December. We excluded optic neuropathy of other causes, a previous diagnosis of MS or systemic diseases associated with ON. Patients underwent brain MRI, visual evoked potentials (VEPs), somatosensory evoked potentials (SEPs) and brainstem auditory evoked potentials (BAEPs). The mean interval between ON onset and MRI was 3.1 months. 24 patients were treated with corticosteroids in different ways: oral prednisone (14) and intravenous methylprednisolone (10). Mean duration of the follow-up was 4.5 years in 26 patients. RESULTS: Brain MRI detected white matter areas with increased signal in 10 of 25 patients (40%). Eight (30%) had bilateral anormalities on VEP, while SEPs and BAEPs revealed anormalities in one patient (5.5%). Two out 26 patients (7.7%) developed CDMS; one was treated with oral prednisone and the other with intravenous corticosteroids. No patients with normal MRI developed MS compared to 20% of patients with lesions on initial brain MRI. The only patient with abnormal SEPs and BAEPs did not develop MS. CONCLUSIONS: We found in our population low rate of developing CDMS with higher risk for those ON with abnormalities on initial brain MRI.     

Effect of antithyroid drugs on hydroxyl radical formation and alpha-1-proteinase inhibitor inactivation by neutrophils: therapeutic implications

The release of proteolytic enzymes and generation of strong oxidants such as the hydroxyl radical by activated neutrophils has been proposed to play an important role in mediating toxin-induced liver injury. The antithyroid drug propylthiouracil protects against liver injury induced by many hepatotoxic agents and markedly reduces mortality in patients with alcoholic liver disease. However, the mechanism(s) by which propylthiouracil protects against liver injury is not well understood. The present studies investigate the effect of antithyroid drugs on proteolytic enzyme activity and on hydroxyl radical generation from activated neutrophils. In the presence of hydrogen peroxide and chloride, neutrophil myeloperoxidase, an enzyme from the same gene superfamily as thyroid peroxidase, generates hypochlorous acid which inactivates alpha-1-proteinase inhibitor (A1PI) present in serum. This inactivation allows neutrophil-released proteolytic enzymes to attack cells. In the present study myeloperoxidase activity was inhibited fully at therapeutic concentrations by antithyroid drugs (propylthiouracil and methimazole). Antithyroid drugs fully prevented hypochlorous acid formation, and prevented neutrophil-mediated inactivation of A1PI, with concomitant blockage of proteolytic activity. Conversely, generation of both superoxide and hydroxyl radicals by activated neutrophils was unaffected by propylthiouracil. The production of these oxygen radicals was fully inhibited by the NADPH oxidase inhibitor diphenylene iodonium chloride, however. These studies indicate that antithyroid drugs are unlikely to prevent cell injury by inhibiting hydroxyl radical generation or by scavenging hydroxyl radicals, but are likely to exert their hepatoprotective anti-inflammatory action by inhibiting neutrophil myeloperoxidase, an enzyme akin to thyroid peroxidase.