Search

Methylmercury (MeHg) is a highly toxic form of mercury that can bioaccumulate in fish tissue. Methylmercury is produced by anaerobic bacteria, many of which are also capable of MeHg degradation. In addition, demethylation in surface waters can occur via abiotic sunlight-mediated processes. The goal of the present study was to understand the relative importance of microbial Hg methylation/demethylation and abiotic photodemethylation that govern the mass of MeHg within an aquatic system. The study location was the Hells Canyon complex of 3 reservoirs on the Idaho–Oregon border, USA, that has fish consumption advisories as a result of elevated MeHg concentrations. Our study utilized stable isotope addition experiments to trace MeHg formation and degradation within the water column of the reservoirs to understand the relative importance of these processes on the mass of MeHg using the Water Quality Analysis Simulation Program. The results showed that rates of MeHg production and degradation within the water column were relatively low (0.5 m below the surface. These results can be used to identify the relative importance of MeHg processes that can help guide reservoir management decisions.

This article proposes a compact trench-assisted space-modulated junction termination extension (TSM-JTE) design for high-voltage 4H-silicon carbide (SiC) devices. In this design, trench structures are introduced into the JTE region to effectively split the termination region into three functional zones. The proposed termination structure is cost effective in terms of the chip area it occupies; for devices rated at 10 kV, the termination structure extends the edge of the device by only $250~\mu \text{m}$ . Requiring only one implant, it is relatively cheap to fabricate, while a wide implantation dose window endures that is relatively insensitive to variations in dose that may occur during processing. The same advantages occur at 20 kV, the TSM-JTE proving to have the best tradeoff between maximum breakdown voltage and implantation window, compared with other single implant termination designs, achieving this in $500~\mu \text{m}$ of termination length. At 3.3 kV, a 110- $\mu \text{m}$ TSM-JTE retains its advantages over the other JTE designs, but floating field rings are expected to consume less area, though this is not the case at the higher voltages.

Metal and metal oxide nanoparticles (NPs) have been increasingly utilized in many industries to harness their documented antibacterial properties. However, the mechanism(s) of action is still debated in the literature. The aim of this study is to understand how changes in outer membrane charge of a test bacteria Haemophilus influenzae alter the antibacterial activity of ZnO NPs of average sizes of 20 nM and 60 nM. H. influenzae outer membrane charge was altered through use of the wild strain (Rd) and mutant lines H543 and H446. Results indicate that antibacterial effects are both concentration and size dependent, with smaller NPs causing increased antibacterial response. Most critically, antibacterial assays and collected TEM images demonstrate that increasing negative charge on the outer membrane of bacteria decreased the antibacterial activity of the ZnO NPs. Finally, this work demonstrates the possibility of using ZnO NPs to treat H. influenzae infection in clinical settings.

A systematic post-deposition annealing study on Silicon Carbide (SiC) metal-oxide-semiconductor capacitors (MOSCAPs) using atomic layer deposition (ALD)-deposited silicon dioxide (SiO2) layers was carried out. Anneals were done in oxidising (N2O), inert (Ar) and reducing (H2:N2) ambients at elevated temperatures from 900°C to 1300°C for 1 hour. Electrical characterisation results show that the forming gas treatment at 1100°C reduces the flatband voltage to 0.23 V from 10 V for as-deposited SiO2 layers. The density of interface traps (DIT) was also reduced by one order of magnitude to 2×1011 cm-2 eV-1 at EC-ET = 0.2 eV. As an indicator of the improvement, characterisation by x-ray photoelectron spectroscopy (XPS) showed that silicon enrichment present in as-deposited layers was largely reduced by the forming gas anneal, improving the stoichiometry. Time-dependent dielectric breakdown (TDDB) results showed that the majority of forming gas annealed samples broke down at breakdown fields of 12.5 MV × cm-1, which is about 2.5 MV × cm-1 higher than for thermally oxidised samples.

3.3 kV Schottky barrier diodes and Junction Barrier Schottky diodes have been fabricated, employing a phosphorous pentoxide $\left(P_{2}O_{5}\right)$ surface treatment prior to metal deposition in an attempt to further condition the power device’s interface. For SBD structures, the treatment consistently reduces the leakage current in molybdenum, tungsten and niobium SBDs, for the tungsten treatment by more than four orders of magnitude. X-ray photoelectron spectroscopy (XPS) analysis on the treated SBD interface revealed formation of a metal phosphate between $P_{2}O_{5}$ and the metal. When compared to an untreated sample, the $P_{2}O_{5}$ treatment has increased the valence band to fermi level offset by 0.2 eV to 3.25 eV, indicating that the treatment results in a degenerately n-doped SiC surface. When applied to fully optimised 3.3 kV JBS power structures utilizing a hybrid JTE design, $P_{2}O_{5}$ treatments improved blocking capabilities across the entire dataset by as much as 1,000 V.

Passivation treatments applied prior to Mo metallisation on Silicon Carbide (SiC) Schottky rectifier and metal-oxide-semiconductor capacitor (MOSCAP) structures are studied. A control sample and two treatments, comprising of an O2 oxidation and a phosphorus pentoxide (P2O5) deposition, were studied. Electrical characterisation results show that P2O5 treatment improves the homogeneity of the diodes, with the ideality factor reducing to 1.02 and the leakage current reducing by three orders of magnitude to 2×10-5 A/cm2. Furthermore, the SBH was lowered by 0.11 eV and the variance of all the P2O5 treated Schottky characteristics over the batch reduced. Characterisation by X-ray photoelectron spectroscopy (XPS) showed that the stoichiometry, the Si:C ratio, of the SiC below the contact increased from 0.93:1 before treatment to 0.97:1 after P2O5 treatment.

We have experimentally verified a compact trench-assisted space-modulated junction termination extension (TSM-JTE) structure which has been designed for high voltage SiC devices. The proposed termination design introduces shallow trench structures into the conventional JTE implanted region, effectively creating a multi-zone JTE with a single implant, and hence greatly broadens the process window for a JTE termination. The TSM-JTE structure is compact and cost effective especially at higher voltages (≥ 10 kV) as it consumes less chip area while requiring only a single implant for the termination region. In this paper, 5 kV and 10 kV SiC PiN diodes have been fabricated and characterized.

This letter reports on the improvement of a SiO2 layer formed by atomic layer deposition on 4H-SiC, using a post-deposition anneal in forming gas ambient. Capacitance–voltage measurements revealed good electrical properties, compared to a thermal oxide which was grown in N 2 O, with flatband voltage values averaging at -0.29 V and a low positive mobile ion charge density in the order of 1010 cm−2. XPS analysis revealed the FG annealed sample to have the most Si rich interface comparatively to other PDAs, with a C:Si ratio of 0.72, allowing more Si bonds to be terminated. SIMS analysis identified an increase in hydrogen near the interface of the FG-annealed sample with a peak concentration of 2.12 × 1021 cm−3. It is concluded that the improvement in electrical performance is due to the hydrogen passivating trap states at the SiO2/4H-SiC interface.

Nitrates in drinking water have been hypothesized to cause cancer. In the current meta-data analysis based study, we investigate if populations having high nitrate concentrations in drinking water have increased incidence rates of cancer. The hypothesis was tested using the county level cancer incidence rate data obtained from the Center for Disease Control, and nitrate data obtained from the individual water system’s consumer confidence reports. Results indicate that a nitrate concentration in drinking water does have a preventative effect on the Kidney and Renal Pelvic, Larynx, Lung and Bronchus, and Oral and Pharynx cancers. Analyzing the results based on sex and race, results show that nitrate in drinking water has a more preventative effect on the white population, irrespective of sex. For the Black and Hispanic population, the effect was pronounced in the male populations. Overall, the results show that, within the safe limits, nitrates in drinking water could have beneficial roles.

Knowledge of the mechanical properties and stability of thin film structures is important for device operation. Potential failures related to crack initiation and growth must be identified early, to enable healing through e.g. annealing. Here, three square suspended membranes, formed from a thin layer of cubic silicon carbide (3C-SiC) or germanium (Ge) on a silicon substrate, were characterised by their response to ultrasonic excitation. The resonant frequencies and mode shapes were measured during thermal cycling over a temperature range of 20–100 °C. The influence of temperature on the stress was explored by comparison with predictions from a model of thermal expansion of the combined membrane and substrate. For an ideal, non-cracked sample the stress and Q-factor behaved as predicted. In contrast, for a 3C-SiC and a Ge membrane that had undergone vibration and thermal cycling to simulate extended use, measurements of the stress and Q-factor showed the presence of damage, with the 3C-SiC membrane subsequently breaking. However, the damaged Ge sample showed an improvement to the resonant behaviour on subsequent heating. Scanning electron microscopy showed that this was due to a self-healing of sub-micrometer cracks, caused by expansion of the germanium layer to form bridges over the cracked regions, with the effect also observable in the ultrasonic inspection. [2020-0017]

Despite the recent advances in 3C-SiC technology, there is a lack of statistical analysis on the reliability of SiO 2 layers on 3C-SiC, which is crucial in power MOS device developments. This article presents a comprehensive study of the mediumand long-term time-dependent dielectric breakdowns (TDDBs) of 65-nm-thick SiO 2 layers thermally grown on a state-of-the-art 3C-SiC/Si wafer. Fowler-Nordheim (F-N) tunneling is observed above 7 MV/cm and an effective barrier height of 3.7 eV is obtained, which is the highest known for native SiO 2 layers grown on the semiconductor substrate. The observed dependence of the oxide reliability on the gate active area suggests that the oxide quality has not reached the intrinsic level. Three failure mechanisms were identified and confirmed by both medium- and long-term results. Although two of them are likely due to extrinsic defects from material quality and fabrication steps, the one dominating the high field (>8.5 MV/cm) should be attributed to the electron impact ionization within SiO 2 . At room temperature, the field acceleration factor is found to be ≈0.906 dec/(MV/cm) for high fields, and the projected lifetime exceeds 10 years at 4.5 MV/cm., This work was part of the Challenge project, founded by European Commission, ID 720827.

The role of plasma membrane transporters in the nephrotoxicity of two antiretroviral drugs, cidofovir and tenofovir, was studied in primary cultures of human proximal tubular (hPT) cells. Cells were grown on Transwell filter inserts to maintain epithelial polarity and access to either the apical or basolateral plasma membrane. The function of relevant membrane transporters, organic anion transporter 1 and 3 (OAT1/3), P-glycoprotein (multidrug resistance protein-1; P-gp or MDR1), and organic cation transporter 2 (OCT2), was validated by measurements of apical-to-basolateral and basolateral-to-apical fluxes of furosemide, digoxin, and metformin, respectively. Acute cytotoxicity of cidofovir (0, 10, 50, 150, or 300 μM) in the absence or presence of 500 μM probenecid, tenofovir disoproxil fumarate (0, 20, 90, 180, or 360 μM) in the absence or presence of 500 μM probenecid, or cisplatin (0, 20, 90, 180, or 360 μM) as a positive control in the absence or presence of 500 μM cimetidine, was assessed after 4-h incubations by determinations of release of lactate dehydrogenase (LDH), γ-glutamyltransferase (GGT), N-acetyl-β-d-glucosaminidase (NAG), or Kidney Injury Molecule-1 (KIM-1). Cell death generally agreed with each of the four biomarkers, was generally greater when cidofovir or tenofovir was added to the upper compartment, and was markedly diminished in the presence of the appropriate transport inhibitor. Additionally, the extent of cytotoxicity caused by the two antiviral drugs was similar to that caused by cisplatin. The results demonstrate the importance of plasma membrane transport of antiviral drugs to elicit cytotoxicity in the hPT cell.

The alloy silicon carbon (Si1-yCy) has various strain engineering applications. It is often implemented as a dopant diffusion barrier and has been identified as a potential buffer layer for cubic silicon carbide (3C-SiC) heteroepitaxy. While suspended membranes formed from thin films of semiconductor (Ge and 3C-SiC) and dielectric (Si3N4) materials have been well studied, pseudomorphic, defect-free epilayers under high levels of tensile strain have received little attention. Often, tensile strain is a desired quality of semiconductors and enhancing this property can lead to various benefits of subsequent device applications. The strain state and crystalline tilt of suspended Si1-yCy epilayers have been investigated through micro-X-ray diffraction techniques. The in-plane tensile strain of the alloy was found to increase from 0.67% to 0.82%. This strain increase could reduce the C content required to achieve suitable levels of strain in such alloys and further strain enhancement could be externally induced. The source of this strain increase was found to stem from slight tilts at the edges of the membranes, however, the bulk of the suspended films remained flat. The novel process utilised to fabricate suspended Si1-yCy thin-films is applicable to many other materials that are typically not resistant to anisotropic Si wet etchants.

Two commercial 1.2 kV SiC MOSFETs have been extensively characterised from 30 to 320 K. The temperature dependence of their I/V characteristics, threshold voltage, and breakdown voltage has been examined and are presented in this paper. Overall, the measured characteristics of both devices demonstrate very similar temperature dependencies and it is shown that below ~100 K any further decrease in temperature has little effect on any of the tested characteristics. Increasing temperature beyond 100 K results in a decrease in drain current for a given drain-source and gate-source voltage, a decrease in threshold voltage, and an increase in breakdown voltage. Successful attempts have been made to model the results of these tests by applying theories found in the literature.

For photovoltaics, switching the p‐type dopant in silicon wafers from boron to indium may be advantageous as boron plays an important role in the light‐induced degradation mechanism. With the continuous Czochralski crystal growth process it is now possible to produce indium doped silicon substrates with the required doping levels for solar cells. This study aims to understand factors controlling the minority carrier lifetime in such substrates with a view to enabling the quantification of the possible benefits of indium doped material. Experiments are performed using temperature‐dependent Hall effect and injection‐dependent carrier lifetime measurements. The recombination rate is found to vary linearly with the concentration of un‐ionized indium which exists in the sample at room temperature due to indium's relatively deep acceptor level at 0.15 eV from the valence band. Lifetime in indium doped silicon is also shown to degrade rapidly under illumination, but to a level substantially higher than in equivalent boron doped silicon samples. A window of opportunity exists in which the minority carrier lifetime in degraded indium doped silicon is higher than the equivalent boron doped silicon, indicating it may be suitable as the base material for front contact photovoltaic cells.

At present, including failed attempts, it takes about 15 years and costs totaling up to $2.6 billion to take a promising new compound from laboratory to the market. Increasing drug resistance among microbial pathogens has led to a growing interest in exploring novel methods to enhance the efficacy of existing drugs. Combination therapies involving two or more known antimicrobial methods, particularly those involving nanoparticles for combating the clinical problems associated with antibiotic resistance, have been garnering interest. In the current study, we determined whether a combination therapy involving silver nanoparticles, which are known for their antimicrobial activity, and the widely used antibiotic ampicillin can be effective against methicillin-resistant Staphylococcus aureus (MRSA). In the presence of sub-lethal dose of silver nanoparticles, ampicillin was found to be effective against MRSA. Indeed, the results show that silver nanoparticles and ampicillin act synergistically, with the effect being more pronounced when a lower concentration of ampicillin is present. When present at a higher concentration, ampicillin coats the silver nanoparticle, preventing the direct interaction of nanoparticles and bacteria. This study discusses the possible applications of combination antimicrobial therapies involving silver nanoparticles for therapeutic treatments.

The objectives of this study were to determine the absolute bioavailability of lesinurad and to characterized its disposition in humans.The oral bioavailability assessment was performed using a clinical design of simultaneous dosing of a therapeutic oral dose of lesinurad with an intravenous infusion of [14C]lesinurad microdose. The bioavailability of lesinurad was determined to be 100%.The disposition of lesinurad in humans involves hepatic oxidation and renal elimination following administration of oral [14C]lesinurad dose.Metabolism of lesinurad occurred post-systemically with low circulating levels of metabolites 14C]lesinurad microdose. The bioavailability of lesinurad was determined to be 100%. The disposition of lesinurad in humans involves hepatic oxidation and renal elimination following administration of oral [14C]lesinurad dose. Metabolism of lesinurad occurred post-systemically with low circulating levels of metabolites

Effects of ICP power and pressure on microtrenching, striation, roughness and sidewall angles in SF6 based ICP-RIE etching of SiC have been studied. The results show that ICP RIE etching parameters such as ICP power and pressure can effect both striation and microtrenches and these challenges could be eliminated by optimizing etching parameters.

Germanium membranes and microstructures of 50-1000 nm thickness have been fabricated by a combination of epitaxial growth on a Si substrate and simple etching processes. The strain in these structures has been measured by high-resolution micro-X-ray diffraction and micro-Raman spectroscopy. The strain in these membranes is extremely isotropic and the surface is observed to be very smooth, with an RMS roughness below 2 nm. The process of membrane fabrication also serves to remove the misfit dislocation network that originally forms at the Si/Ge interface, with benefits for the mechanical, optical and electrical properties of the crystalline membranes., This work was supported by the EPSRC, Projects. EP/F040784/1, and EP/J001074/1; ERC grant #202735, “NonContactUltrasonic”; NANOFUNCTION Network of Excellence, funded by the European Commission 7th Framework Programme (ICT-FP7, #228464).

The hole-phonon energy loss rate in silicon is measured at phonon temperatures ranging from 300 mK to 700 mK. We demonstrate that it is approximately an order of magnitude higher than the corresponding electron-phonon energy loss rate over an identical temperature range.

Purpose. Congenital retinal macrovessels (CRM) represent rare aberrant vasculature of the retinal vessels that can supply or drain the macula. In this report, the optical coherence tomography angiography features of a congenital retinal macrovessel are discussed. Methods. The history and examination findings are presented alongside swept-source OCT angiography with corresponding B scan and en face OCT imaging. Patients. The case is a 12-year-old female patient with excellent best-corrected visual acuity in both eyes. Results. Swept-source OCT angiography demonstrated considerable loss of the foveal avascular zone at the levels of the superficial and deep capillary plexus. Discussion. In this case there was no detrimental effect on vision despite anatomical loss of the foveal avascular zone.

Verinurad (RDEA3170) is a second generation selective uric acid reabsorption inhibitor for the treatment of gout and asymptomatic hyperuricemia. Following a single oral solution of 10-mg dose of [14C]verinurad (500 μCi), verinurad was rapidly absorbed with a median time to occurrence of maximum observed concentration (Tmax) of 0.5 hours and terminal half-life of 15 hours. In plasma, verinurad constituted 21% of total radioactivity. Recovery of radioactivity in urine and feces was 97.1%. Unchanged verinurad was the predominant component in the feces (29.9%), whereas levels were low in the urine (1.2% excreted). Acylglucuronide metabolites M1 (direct glucuronidation) and M8 (glucuronidation of N-oxide) were formed rapidly after absorption of verinurad with terminal half-life values of approximately 13 and 18 hours, respectively. M1 and M8 constituted 32% and 31% of total radioactivity in plasma and were equimolar to verinurad on the basis of AUC ratios. M1 and M8 formed in the liver were biliary cleared with complete hydrolysis in the GI tract, as metabolites were not detected in the feces and/or efflux across the sinusoidal membrane; M1 and M8 accounted for 29.2% and 32.5% of the radioactive dose in urine, respectively. In vitro studies demonstrated that CYP3A4 mediated the formation of the N-oxide metabolite (M4), which was further metabolized by glucuronyl transferases (UGTs) to form M8, as M4 was absent in plasma and only trace levels were present in the urine. Several UGTs mediated the formation of M1, which could also be further metabolized by CYP2C8. Overall, the major clearance route of verinurad is metabolism via UGTs and CYP3A4 and CYP2C8.

A rapid and sensitive LC-MS/MS method has been developed and fully validated for simultaneous quantification of aspirin (ASP), salicylic acid (SLA), rosuvastatin (RVT), rosuvastatin lactone (RVL) and N-desmethyl rosuvastatin (DM RVT) in human plasma using a polarity switch with 400 μL of sample human blank plasma. Deuterated Internal Standards (IS) were used for each analyte. The solid phase extraction was used as sample preparation techniques. Chromatograph was monitored on a zorbax SB-phenyl column with a gradient mode with API-5500 triple quadrupole mass spectrometer as detector. The assay method was validated over the concentration range of 0.1-25 ng/mL for RVT; 50-10000 pg/mL for RVL and DMRVT; 5-2000 ng/mL for ASP; and 0.1-8 μg/mL for SLA. Intra and inter-day precision and accuracy were within acceptance limit. The mean recovery was >85% for all analytes. The analytes were stable at RT for 6 h in solution, at 2-8°C for 15 days in solution, for RT for 6 h in plasma, RT for 2 h in blood, till 3 freeze/thaw cycles, 104 h in auto-sampler at 6°C. This proposed method can be used for measurement of reliable concentration for dossier submission.

Here, we describe the mechanism of diphenyl α-aminoalkylphosphonate ester derivatives as potent inhibitors of prostate-specific antigen (PSA), a likely protease responsible for the advancement of prostate tumor progression. The AutoDock 4.2 molecular docking suite was utilized to model covalent and noncovalent binding of this class of inhibitors to predict crystallographic poses and compare experimental IC50 dose-response curves and in silico potencies for providing future more specific rational drug design. The new lead compound R/S-diphenyl[N-benzyloxycarbonylamino(4-carbamoylphenyl)methyl]phosphonate is being reported in this study as a potent inhibitor of PSA activity (IC50 = 250 nM; AutoDock Score = -8.29/-9.14 kJ·mol(-1) for R/S). Molecular dynamics (MD) simulations using GROMACS 4.6.5 was used to obtain trajectories of the top ligand and validate key interactions in the binding complex. A hydrogen-bonding map was used to confirm interactions between the lead compound and residues THR190, SER217, and SER227 in the P1 pocket. The modeling study introduces novel aminoalkylphosphonates as a potential drug candidate for targeting PSA by optimizing P1 binding affinities.

A thin, flat and single crystal membrane on which to mount sensors is generally required for integration with electronics through standard silicon processing technology. We present an approach to producing single crystal membranes of germanium with in-built tensile strain, which serves to keep the membrane flat and ripple free, and demonstrate a 600 nm thick, free-standing 1 mm2 Ge membrane. We convert the fabrication technique into an integrated-circuit compatible wafer scale process to produce 60 nm thin membranes with large areas of 3.5 mm2. The single crystal Ge membrane provides an excellent platform for further epitaxial growth or deposition of materials.

The increasing use of engineered nanoparticles (NPs) in industrial and household applications will very likely lead to the increased release of such materials into the public sewer systems. During the wastewater treatment process, some fraction of NPs would always be concentrated in the biosolids. When biosolids is applied on the agricultural land, NPs are introduced into the soil matrix. In the current study we investigate the influence of five different metal nanoparticles present in biosolids on soil microbial community as a function of time. Results indicate that ZnO and Zero Valent Cu NPs were not toxic to soil bacterial community. Biosolids mixed with Ag NPs and TiO2 (both anatase and rutile phase) in contrast changed the bacterial richness and composition in wavering pattern as a function of time. Based on the observations made in the study, we suggest caution when interpreting the toxicity of NPs based on single time point study.

The fate of engineered zero-valent copper nanoparticles (Cu NPs) in soils collected from geographically-distinct regions of the continental United States and incubated under controlled conditions was investigated with respect to NP affinity for soil surfaces and changes in speciation, as well as their impact on bacterial communities. Soil geochemical properties had a great influence on Cu NP migration and transformation. Translocation of Cu NPs was low in soils enriched in organic matter and high in clay and sandy soils. X-ray absorption spectroscopic analysis showed that the highest rates for transformation to Cu ions and adsorption complexes was in acidic soils. Although there was some change in overall bacterial community richness at the level of order in experimental soil, the level of perturbation was evident in side-by-side comparisons of orders using a 50% microbial community change value (MCC(50)). This assessment revealed that generally, Sphingomonas, known for its importance for remediation, and Rhizobiales, symbiotic partners with certain plants appeared susceptible to Cu NPs and their transformation products. The ecological importance of organisms from these orders and its greater vulnerability to Cu NPs suggests need for future targeted studies.

Nevirapine (NVP) is associated with hepatotoxicity in 1–5% of patients. In rodent studies, NVP has been shown to cause hepatic enzyme induction, centrilobular hypertrophy, and skin rash in various rat strains but not liver toxicity. In an effort to understand whether NVP is metabolized differently in a transiently inflamed liver and whether a heightened immune response alters NVP-induced hepatic responses, female brown Norway rats were dosed with either vehicle or NVP alone (75 mg/kg/day for 15 days) or galactosamine alone (single intraperitoneal [ip] injection on day 7 to mimic viral hepatitis) or a combination of NVP (75/100/150 mg/kg/day for 15 days) and galactosamine (single 750 mg/kg ip on day 7). Livers were collected at necropsy for histopathology, matrix-assisted laser desorption/ionization imaging mass spectrometry and gene expression. Eight days after galactosamine, hepatic fibrosis was noted in rats dosed with the combination of NVP and galactosamine. No fibrosis occurred with NVP alone or galactosamine alone. Gene expression data suggested a viral-like response initiated by galactosamine via RNA sensors leading to apoptosis, toll-like receptor, and dendritic cell responses. These were exacerbated by NVP-induced growth factor, retinol, apoptosis, and periostin effects. This finding supports clinical reports warning against exacerbation of fibrosis by NVP in patients with hepatitis C.

et al., In this work we studied the gate oxidation temperature and nitridation influences on the resultant 3C-SiC MOSFET forward characteristics. Conventional long channel lateral MOSFETs were fabricated on 3C-SiC(100) epilayers grown on Si substrates using five different oxidation processes. Both room temperature and high temperature (up to 500K) forward IV performance were characterised, and channel mobility as high as 90cm2 /V.s was obtained for devices with nitrided gate oxide, considerable higher than the ones without nitridation process (~70 cm2/V.s).

Reverse terrace graded buffers are proposed for high quality high Ge content Si0.23Ge0.77 buffers. The buffer structure allows the effects of applied thermal budget and grading rate to be separated and compared to previously reported reverse linearly graded virtual substrates. A reduction in threading dislocation density to 2.1 × 106 cm− 2 and an enhanced relaxation is found for these terrace graded structures of almost identical thickness and twice the strain gradient of the linear graded structures, whilst a smooth surface is retained with an rms roughness of just 1.9 nm.

Interest is growing in understanding not only the impact of individual nanoparticles (NPs) on ecosystems but also the effect of NP mixtures. In the present study, the impact of a combination of three different NPs, silver, copper, and silica (all at 0.022%, w/w), on an arctic microbial community was investigated. After adding the NPs, soil microcosms were incubated for 176 d, and subsequent estimates of microbe diversity were obtained using culture-dependent and culture-independent assessments. The treated soil appeared to show a reduction in the ability to use carbohydrate and amino acid substrates and demonstrated an altered pattern of major fatty acid peaks. Polymerase chain reaction–denaturing gradient gel electrophoresis showed consistent differences in the pattern of predominant rRNA gene sequences. Although this is an initial investigation of soil contaminated with mixed NPs, these results demonstrate that even at the relatively modest concentrations used such pollutants have the potential to disrupt microbial communities. Environ. Toxicol. Chem. 2012;31:131–135. © 2011 SETAC

A study of Ge epilayer growth directly on a Si(001) substrate is presented, following the two temperature Ge layer method. In an attempt to minimize the overall thickness while maintaining a good quality Ge epilayer, we have investigated the effect of varying the thickness of both the low and high temperature Ge layers, grown at 400 °C and 670 °C, respectively, by reduced pressure chemical vapor deposition. We find that the surface of the low temperature (LT) seed layer has a threading dislocation density (TDD) to the order of 10 11 cm − 2 . On increasing the LT layer thickness from 30 nm to 150 nm this TDD decreases by a factor of 2, while its roughness doubles and degree of relaxation increases from 82% to 96%. Growth of the high temperature (HT) layer reduces the TDD level to around 10 8 cm − 2 , which is also shown to decrease with increasing layer thickness. Both the surface roughness and degree of relaxation reach stable values for which increasing the thickness beyond about 700 nm has no effect. Finally, annealing the HT layer is shown to reduce the TDD, without affecting the degree of relaxation. However, unless a thick structure is used the surface roughness increases significantly on annealing.

After a long period of developing integrated circuit technology through simple scaling of silicon devices, the semiconductor industry is now embracing technology boosters such as strain for higher mobility channel material. Germanium is the logical supplement to enhance existing technologies, as its material behaviour is very close to silicon, and to create new functional devices that cannot be fabricated from silicon alone (Hartmann et al. (2004) [1]). Germanium wafers are, however, both expensive and less durable than their silicon counterparts. Hence it is highly desirable to create a relaxed high quality Ge layer on a Si substrate, with the provision that this does not unduly compromise the planarity of the system. The two temperature method, proposed by Colace et al. (1997) [2], can give smooth (RMS surface roughness below 1 nm) and low threading dislocation density (TDD

Microwave (MW) assisted enzymatic polymerizations is an area that is largely unexplored. In the current study, the effect of MW reaction parameters on poly-e-caprolactone (PCL) properties has been investigated using a statistical design. A {3,5} modified mixture experimental design was used to identify the parameter values that gave the desired properties of PCL. The three process parameters that were tested are temperature, MW intensity, and the reaction time. Experimental results showed that in the range of values tested, temperature had the highest positive influence on the properties of PCL, whereas high MW irradiation is not desirable. A cubic regression model was developed and optimal process parameters were obtained using this model. Conducting the polymerization reaction under optimal conditions (90°C, 240 min, 50 W), PCL with M n of 20,624 and polydispersity index of 1.2 were obtained. The regression model was validated by carrying out validation experiments and by 3D visualization.

Bi-axial tensile strained Si epilayers with extremely high lattice mismatch strain up to 2.13% were grown from a disilane (Si2H6) precursor on Si1-xGex/Si(100) VSs by Reduced Pressure Chemical Vapour Deposition. We discuss the conditions under which fully strained Si epilayers of the required thickness can be grown. By demonstrating a fully strained 23 nm Si layer on a fully relaxed Si0.45Ge0.55(100) VS, this work indicates the potential for realizing high performance s-Si n- and p-MOSFETs on standard Si(100) substrates. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

SiC schottky diodes take advantage of the material's superior reverse breakdown voltage when compared to Silicon (Si) [1]. However, when considered for MOSFET applications, the high concentration of interface traps at the SiC/SiO2 interface reduce the material's already low channel mobility [2]. Therefore, a Ge/SiC heterojunction solution becomes an attractive prospect, whereby the Ge forms the control region after being epitaxially grown on the SiC. With a well established Ge-High K dielectric technology [3], a carbon-free oxide would exist, leaving a channel-region with a mobility approximately four times that of SiC.

Alkaline sucrose solution was demonstrated to be a good solvent for the solubilization of water-insoluble drugs. At high concentration and alkaline pH, sucrose solubilizes water-insoluble molecules through intramolecular conformations. Tetracyline and chloramphenicol, when dissolved in alkaline sucrose solution, retained their bactericidal activity. Gel permeation-chromatography analysis and atomic-force-microscopy studies confirmed the formation of sucrose-antibiotics complex.

The excess molar volume VmE, viscosity deviation Δη, and excess Gibbs energy of activation ΔG⁎E of viscous flow have been investigated from the density ρ and viscosity η measurements of binary mixtures of methanol with n-butylamine and di-n-butylamine over the entire range of mole fractions at 303.15, 313.15, and 323.15 K. The systems studied exhibit very strong cross association through strong O–H…N bonding between –OH and –NH– groups. As a consequence of this strong intermolecular association, both the systems have very large negative VmE and positive Δη and ΔG⁎E over entire range of composition and at all the temperatures of investigation. VmE of the studied mixtures is consistently described by the ERAS model. The values of cross association constants KAB illustrate that cross-associates are more pronounced in primary amine mixtures than that in secondary amine.

Short term influence of silica, palladium, gold and copper nanoparticles on a soil microbial community and the germination of lettuce seeds are investigated in this study at two different concentrations of nanoparticles. Results show a statistically insignificant influence of the nanoparticles in the soil on the number of colony forming units, peak areas of methyl ester of fatty acids in the FAME profile or on the total soil community metabolic fingerprint (P > 0.05). Also, all nanoparticles tested in the study influenced the growth of lettuce seeds as measured through shoot/root ratios of the germinated plant (P < 0.05).

The physical and electrical properties of heavily doped silicon (5x10^1^9cm^-^3) deposited by molecular beam epitaxy (MBE) on 4H-SiC are investigated in this paper. Silicon layers on silicon carbide have a broad number of potential applications including device fabrication or passivation when oxidised. In particular, Si/SiC contacts present several atractive material advantages for the semiconductor industry and especially for SiC processing procedures for avoiding stages such as high temperature contact annealing or SiC etching. Si films of 100nm thickness have been grown using a MBE system after different cleaning procedures on n-type (0001) Si face 8^o off 4H-SiC substrates. Isotype (n-n) and an-isotype (p-n) devices were fabricated at both 500 and 900^oC using antimonium (Sb) or boron (B), respectively. X-ray diffraction analysis (XRD) and scanning electronic mircorscope (SEM) have been used to investigate the crystal composition and morphology of the deposited layers. The electrical mesurements were performed to determine the rectifiying contact characteristics and band offsets.

The excess molar volume VE, viscosity deviation Δη, and excess Gibbs energy of activation ΔG*E of viscous flow have been investigated from the density ρ and viscosity η measurements of four binary mixtures of methanol and ethanol with triethylamine and tri-n-butylamine over the entire range of mole fractions at 303.15, 313.15, and 323.15 K. The viscosity data have been correlated with the equations of Grunberg and Nissan, Hind, McLaughlin, and Ubbelohde, Tamura and Kurata, and McAllister. The systems studied exhibit very strong cross association through strong O–H…N bonding between –OH and –N

Approximately 100 billion liters of oil is generated per week as waste from restaurants around the country. Because of health, environmental, and economic factors, current methods of disposal are ineffective for disposal of the restaurant oil wastes. In this study we have investigated the ability of Candida bombicola to fermentatively transform the restaurant oil waste into glycolipids called sophorolipids. Batch and fed-batch studies were carried out using oil waste as the lipid feedstock in Erlenmeyer flasks and in a fermentor. Batch fermentation in a fermentor gave the highest yield of sophorolipids of 34 g L -1 . Fermentation using oleic acid as control feedstock were also carried out. Batch fermentation in the fermentor using this pure fatty acid gave a highest yield of 42 g L -1 . The difference in the sophorolipid yield was attributed to the fatty acid composition of restaurant oil waste.

Cutinase enzymes from fungi have found diverse applications in industry. However, most of the available literature on cutinase production is related to the cultivation of genetically engineered bacteria or yeast cells. In the present study, we use mixture design experiments to evaluate the influence of six nutrient elements on production of cutinase from the fungus Colletotrichum lindemuthianum. The nutritional elements were starch, glucose, ammonium sulfate, yeast extract, magnesium sulfate, and potassium phosphate. In the experimental design, we imposed the constraints that exactly one factor must be omitted in each set of experiments and no factor can account for more than one third of the mixture. Thirty different sets of experiments were designed. Results obtained showed that while starch is found to have negative influence on the production of the enzyme, yeast extract and potassium phosphate have a strong positive influence. Magnesium sulfate, ammonium sulfate, and glucose have low positive influence on the enzyme production. Contour plots have also been created to obtain information concerning the interaction effects of the media components on enzyme production.

Sophorolipids (SLs) are glycolipids produced fermentatively by yeasts such as Candida bombicola, Candida apicola, and Wickerhamiella domercqiae and composed of a dimeric sugar linked with a glycosidic bond to a hydroxyl fatty acid. SLs have generated interest in the pharmaceutical arena because of their wide array of therapeutic benefits. Shah et al. (5) first reported that natural SLs and their first-generation chemical derivatives are efficient microbicidal spermicides, having activities similar to that of nonoxynol-9. Bluth et al. (2) showed that natural SLs are effective septic shock antagonists. Additionally, SLs have been demonstrated to be effective anticancer agents against cancerous cell lines (4). One major drawback of SLs so far has been their cytotoxic activities. While efforts are being made to further chemically modify the molecule to increase its potency and decrease its toxicity, no improvements have been reported. The second generation of SL molecules was generated by conjugating amino acids to a fatty acid side chain (1). However, these molecules were less effective as microbicidal spermicides than first-generation compounds. In the present study, we report the fermentative production of novel SL molecules that have higher antibacterial activities and offer a new backbone for further chemical modifications. The fermentation medium used to produce SLs by Candida bombicola uses glucose as the primary carbon source. Thus, the SL formed has two glucose molecules. We replaced glucose in the fermentation medium with the other sugars described in Table ​Table1.1. The SLs formed in each of the media were extracted and purified per standard protocol (1). Liquid chromatography-mass spectrometry (LC-MS) analyses were carried out for the compounds, and the MIC extracts of compounds with masses from 500 to 800 are shown in Fig. ​Fig.1.1. The peak appearing at 24.5 min in all the chromatograms is caused by the three sophorolipids, viz., a diacetylated lactonic SL with a C18 monounsaturated fatty acid (M+H, 689), a diacetylated lactonic SL with a C18 saturated fatty acid (M+H, 691), and a diacetylated open-ring SL with a monounsaturated fatty acid (M+H, 707). The peak at 25.3 min is also caused by compounds having the same mass. Two peaks for the same mass at different retention times have been reported earlier and are attributed to the attachment of a dimeric sophorose to the hydroxyl group at either the penultimate or the terminal fatty acid carbon, where the later is the minor component for the regioisomers (3). The peak at 33.1 min in all chromatograms is caused by a diacetylated open-ring SL with a saturated C18 fatty acid (M+H, 709). New peaks in the region of 35 to 50 min are caused by SL compounds having M+H values of 603 and 605, corresponding to an unacetylated lactonic SL with a diunsaturated C18 fatty acid and an unacetylated lactonic SL having a monounsaturated C18 fatty acid, respectively. FIG.1. LC-MS spectrum of sophorolipids obtained using different sugar sources in fermentation medium. A, glucose; B, fructose; C, xylose; D, ribose; E, lactose; F, mannose; G, arabinose; H, galactose. LC-MS experiments were conducted with a Shimadzu LCMS-2010EV ... TABLE 1. Antibacterial activities The appearance of new peaks for SLs produced from different sugars in comparison to that produced from glucose in the fermentation medium can be explained by the presence of a different sugar head group in the compound and the inability of the cellular machinery of C. bombicola to acetylate the new sugars. The unacetylated lactonic SLs reaffirm our hypothesis regarding the presence of new sugar heads in the SLs. Since the acetyl group is added to the glucose in the SL head group by the enzyme acetyltransferase, the presence of the unacetylated SLs indicates that the new sugar present in the head group is not glucose. Glucose in the SL head group is the natural substrate for acetyltransferase, and the new sugar head group could be presumed to be composed of molecules different from glucose, on which the enzyme cannot act. It is important to note that all the fermentation media had oleic acid as the lipidic substrate, and thus, no difference in structure could be expected for the fatty acid side chain. Further purification and characterization studies are needed to understand the precise chemical structure of each SL analog. The antibacterial activities of the purified compounds show that SLs are more effective against gram-positive bacteria than gram-negative bacteria (Table ​(Table1).1). Comparing the antibacterial activities of SLs obtained in glucose-containing medium, it could be inferred that SLs obtained from different sugar-containing media differ in their activities against the tested organisms. SLs from arabinose-containing medium are more effective against three of the four gram-positive bacteria tested and against Moraxella sp. than SLs from glucose-containing medium. However, SLs from arabinose show no inhibition of the growth of Escherichia coli. SLs from lactose-containing medium were the most effective compound against Bacillus subtilis. All the efforts so far to generate a clinically viable compound by chemically modifying the SLs from glucose-containing medium have failed; we believe that the molecules generated through the present method will open a new door. With higher activities on their own, these molecules could be hypothesized to lead us to more potent compounds when chemistries similar to that carried out in developing first-generation SLs are used on them.

Yeast Candida bombicola is known to produce sophorolipids from a variety of saccharic and lipidic feed-stocks. In the current study, the influence of fatty acid carbon chain length, unsaturation, source of low-cost industrial lipid feed-stocks, and nickel content in lipid feed-stocks on sophorolipid production by C. bombicola were investigated. Saturated and monounsaturated C18 fatty acid gave the highest levels of sophorolipid production while fatty acids with more than one site of unsaturation gave much lower yields. Sophorolipid production was reduced when shorter (≤C16) and longer (≥C20) fatty acids were fed. The possibility of exploiting low-cost industrial wastes or by-products for sophorolipid production by batch or fed-batch processes was investigated. Tallow fatty acid residue was the best lipid feed-stock for sophorolipid production (120 g/L, fed-batch cultures), while coconut fatty acid residue resulted in the lowest production (40 g/L, fed-batch cultures). Co-feeding coconut fatty acid residue with other feed-stocks improved its substrate value in batch cultures. C. bombicola was tolerant to nickel contamination of up to 112.5 mg/L during sophorolipid production. Nickel contaminated stearic fatty acid residue was transformed to value added sophorolipid product while nickel was sequestered primarily in biomass for safe removal and recovery. Sophorolipid product obtained from nickel contaminated lipid wastes had low nickel levels (

A degenerated wide bandgap semiconductor is a rare system. In general, implant levels lie deeper in the band-gap and carrier freeze-out usually takes place at room temperature. Nevertheless, we have observed that heavily doped n-type degenerated 3C-SiC films are achieved by nitrogen implantation level of ∼6 × 1020 cm−3 at 20 K. According to temperature dependent Hall measurements, nitrogen activation rates decrease with the doping level from almost 100% (1.5 × 1019 cm−3, donor level 15 meV) to ∼12% for 6 × 1020 cm−3. Free donors are found to saturate in 3C-SiC at ∼7 × 1019 cm−3. The implanted film electrical performances are characterized as a function of the dopant doses and post implantation annealing (PIA) conditions by fabricating Van der Pauw structures. A deposited SiO2 layer was used as the surface capping layer during the PIA process to study its effect on the resultant film properties. From the device design point of view, the lowest sheet resistivity (∼1.4 mΩ cm) has been observed for medium doped (4 × 1019 cm−3) sample with PIA 1375 °C 2 h without a SiO2 cap.

Dimethyl sulfoxide (DMSO) is commonly used as a co-solvent to dissolve poorly water-soluble biologically active agents to assess their biological activities such as for enzyme induction. The question addressed was whether DMSO can be assumed to be an inert co-solvent. The influence of DMSO on the production of extracellular enzymes by Pleurotus ostreatus was investigated. DMSO functioned as either an inducer or a repressor, depending on the enzyme studied. The production of laccase and endo-1,4-beta-xylanase increased by 29 and 250%, respectively, in presence of DMSO. However, DMSO repressed the activities of manganese peroxidase, beta-glucosidase, beta-xylanase, and endo-1,4-beta-glucanase by 30, 33, 99 and 16%, respectively. These results raise concerns about the interpretation of bioactivity measurements when DMSO is assumed to function as an inert co-solvent to solubilize water-insoluble molecules.

With global attention and research now focused on looking for the abatement of pollution, white-rot fungi is one of the hopes of the future. The lignin-degrading ability of these fungi have been the focus of attention for many years and have been exploited for a wide array of human benefits. This review highlights the various enzymes produced by white-rot fungi for lignin degradation, namely laccases, peroxidases, aryl alcohol oxidase, glyoxal oxidase, and pyranose oxidase. Also discussed are the various radicals and low molecular weight compounds that are being produced by white-rot fungi and its role in lignin degradation. A brief summary on the developments in research of decolorization of dyes using white-rot fungi has been made.Key words: lignin degradation, white-rot fungi, laccase, peroxidase, radicals, dye decolorization.

We demonstrate electron cooling in silicon using platinum silicide as a superconductor contact to selectively remove the highest energy electrons. The superconducting critical temperature of bulk PtSi is reduced from around 1 K to 0.79 K using a thin film (10 nm) of PtSi, which enhances cooling performance at lower temperatures and enables electron cooling to be demonstrated from 100 mK to 50 mK., 4 pages, 4 figures

Germanium membranes of 50–1000 nm thickness have been fabricated by a combination of epitaxial growth on a Si substrate and simple etching processes. The biaxial tensile strain in these membranes has been measured by high-resolution X-ray diffraction and by ultrasonic vibrational spectroscopy. The later technique also shows that membranes have a Q-factor of ∼3000 at low temperature. The stain in these membranes is extremely isotropic and the surface is observed to be very smooth, with an rms roughness of below 2 nm. The process of membrane fabrication also serves to remove the misfit dislocation network that originally forms at the Si/Ge interface, with benefits for the mechanical, optical and electrical properties of the crystalline membranes.