Characterization of a direct detection device imaging camera for transmission electron microscopy

The complete characterization of a novel direct detection device (DDD) camera for transmission electron microscopy is reported, for the first time at primary electron energies of 120 and 200 keV. Unlike a standard charge coupled device (CCD) camera, this device does not require a scintillator. The DDD transfers signal up to 65 lines/mm providing the basis for a high-performance platform for a new generation of wide field-of-view high-resolution cameras. An image of a thin section of virus particles is presented to illustrate the substantially improved performance of this sensor over current indirectly coupled CCD cameras.     

Bioremediation of polycyclic aromatic hydrocarbons (PAH) in an aged coal-tar-contaminated soil using different in-vessel composting approaches

The biodegradation of 16 USEPA-listed PAHs (SigmaPAHs) during simulated in-vessel composting-bioremediation of an aged coal-tar-contaminated soil amended with fresh green waste compost (FGWC) collected from two landfill sites in the United Kingdom (UK) were studied over 56 days. The experimental design compared three constant temperature profiles (TC=38, 55 and 70 degrees C) with one variable temperature profile including treatment at 70 degrees C to comply with regulatory requirements (TP1). The highest disappearance of SigmaPAHs was observed in the soil amended with FGWC (53.2% and 48.1% SigmaPAHs disappearance in soil amended with FGWC-Site 1 and FGWC-Site 2, respectively) containing lower initial organic mater (TOM) (Initial TOM(FGWC-Site 1)=25.6+/-0.6%相似文献   

Effect of fluid ingestion on muscle metabolism during prolonged exercise

Five trained men were studied during 2 h of cycling exercise at 67% peak oxygen uptake at 20-22 degrees C to examine the effect of fluid ingestion on muscle metabolism. On one occasion, the subjects completed this exercise without fluid ingestion (NF) while on the other they ingested a volume of distilled deionized water that prevented loss of body mass (FR). No differences in oxygen uptake during exercise were observed between the two trials. Heart rate was lower (P < 0.01) throughout exercise when fluid was ingested, and rectal temperature after 2 h of exercise was lower (38.0 +/- 0.2 and 38.6 +/- 0.2 degrees C for FR and NF, respectively; P < 0.01), as was muscle (vastus lateralis) temperature (38.5 +/- 0.4 and 39.1 +/- 0.5 degrees C for FR and NF, respectively; P < 0.05). Resting muscle ATP, creatine phosphate, creatine, glycogen, and lactate levels were similar in the two trials, as were the postexercise ATP, creatine phosphate, and creatine levels. In contrast, muscle glycogen was higher (P < 0.05) and muscle lactate was lower (P < 0.05) after 2 h of exercise in FR compared with NF. Net muscle glycogen utilization during exercise was reduced by 16% when fluid was ingested (318 +/- 46 and 380 +/- 53 mmol/kg dry weight for FR and NF, respectively; P < 0.05). These results indicate that fluid ingestion reduces muscle glycogen use during prolonged exercise, which may account, in part, for the improved performance previously observed with fluid ingestion.     

Further results on the in situ anaerobic corrosion of carbon steel and copper in compacted bentonite exposed to natural Opalinus Clay porewater containing native microbial populations

Since 2012, a long-term in situ corrosion experiment (IC-A) is being conducted in the Mont Terri Underground Research Laboratory in Switzerland to investigate the corrosion behaviour of candidate canister materials in conditions representative of the Swiss concept for the disposal of high-level waste and spent nuclear fuel. To date, carbon steel and various types of copper coatings have been retrieved after different exposure periods of up to 3 years, and characterised to establish the composition of the corrosion product, the morphology of the corroded surface, the nature of the interaction between the metal and the surrounding bentonite, and the microbial populations in the bentonite and surrounding porewater. For carbon steel specimens, a complex corrosion product was identified, consisting predominantly of magnetite. Much less alteration on either the metal or the bentonite was observed in the case of copper samples. Low average anaerobic corrosion rates were measured for carbon steel and a very modest amount of alteration was identified on copper. The density and the initial form of the bentonite had a small influence on the rate of corrosion, across all materials. This paper summarises the results of the experimental programme obtained to date and discusses the relationship observed between exposure time and the evolution of the metal–bentonite interface for both carbon steel and copper.     

In Pursuit of Zero 2.0: Recent Developments in Nonfouling Polymer Brushes for Immunoassays

“Nonfouling” polymer brush surfaces can greatly improve the performance of in vitro diagnostic (IVD) assays due to the reduction of nonspecific protein adsorption and consequent improvement of signal-to-noise ratios. The development of synthetic polymer brush architectures that suppress adventitious protein adsorption is reviewed, and their integration into surface plasmon resonance and fluorescent sandwich immunoassay formats is discussed. Also, highlighted is a novel, self-contained immunoassay platform (the D4 assay) that transforms time-consuming laboratory-based assays into a user-friendly and point-of-care format with a sensitivity and specificity comparable or better than standard enzyme-linked immunosorbent assay (ELISA) directly from unprocessed samples. These advancements clearly demonstrate the utility of nonfouling polymer brushes as a substrate for ultrasensitive and robust diagnostic assays that may be suitable for clinical testing, in field and laboratory settings.     

Impacts of Post-metallisation Processes on the Electrical and Photovoltaic Properties of Si Quantum Dot Solar Cells

As an important step towards the realisation of silicon-based tandem solar cells using silicon quantum dots embedded in a silicon dioxide (SiO₂) matrix, single-junction silicon quantum dot (Si QD) solar cells on quartz substrates have been fabricated. The total thickness of the solar cell material is 420 nm. The cells contain 4 nm diameter Si quantum dots. The impacts of post-metallisation treatments such as phosphoric acid (H₃PO₄) etching, nitrogen (N₂) gas anneal and forming gas (Ar: H₂) anneal on the cells’ electrical and photovoltaic properties are investigated. The Si QD solar cells studied in this work have achieved an open circuit voltage of 410 mV after various processes. Parameters extracted from dark I–V, light I–V and circular transfer length measurement (CTLM) suggest limiting mechanism in the Si QD solar cell operation and possible approaches for further improvement.     

Ductile–brittle transition of polycrystalline iron and iron–chromium alloys

Fracture toughness of polycrystalline Fe, Fe–3%Cr and Fe–9%Cr was measured by four-point bending of pre-cracked specimens at temperatures between 77 K and 150 K and strain rates between 4.46 × 10⁻⁴ and 2.23 × 10⁻² s⁻¹. For all materials, fracture behaviour changed with increasing temperature from brittle to ductile at a distinct brittle–ductile transition temperature (T_c), which increased with increasing strain rate. At low strain rates, an Arrhenius relation was found between T_c and strain rate in each material. At high strain rates, T_c was at slightly higher values than those expected from extrapolation of the Arrhenius relation from lower strain rates. This shift of T_c was associated with twinning near the crack tip. For each material, use of an Arrhenius relation for tests at strain rates at which specimens showed twinning gave the same activation energy as for the low strain rate tests. The values of activation energy for the brittle–ductile transition of polycrystalline Fe, Fe–3%Cr and Fe–9%Cr were found to be 0.21, 0.15 and 0.10 eV, respectively, indicating that the activation energy for dislocation glide decreases with increasing chromium concentration in iron.     

Do Images of Biskyrmions Show Type‐II Bubbles?

The intense research effort investigating magnetic skyrmions and their applications for spintronics has yielded reports of more exotic objects including the biskyrmion, which consists of a bound pair of counter‐rotating vortices of magnetization. Biskyrmions have been identified only from transmission electron microscopy images and have not been observed by other techniques, nor seen in simulations carried out under realistic conditions. Here, quantitative Lorentz transmission electron microscopy, X‐ray holography, and micromagnetic simulations are combined to search for biskyrmions in MnNiGa, a material in which they have been reported. Only type‐I and type‐II magnetic bubbles are found and images purported to show biskyrmions can be explained as type‐II bubbles viewed at an angle to their axes. It is not the magnetization but the magnetic flux density resulting from this object that forms the counter‐rotating vortices.     

Decoupled optimal design for power electronic circuits with adaptive migration in coevolutionary environment

This paper presents a genetic based decoupled optimal design method for power electronics circuit design using an adaptive collaboration approach in a cooperative coevolutionary environment. The circuit parameters of the power conversion stage and the feedback network of a buck regulator are optimized through two parallel coadaptive genetic based optimization processes. The best candidate of the tunable parameters in one evolutionary process for the design of the power conversion stage is merged to the other evolutionary process for the design of the feedback network as untunable factors through a collaboration controller in which the collaboration strategy is adaptively controlled by a first-order projection of the maximum and minimum bounds of the fitness value of the genes representing the circuit design parameters in each generation. The proposed design methodology is suitable for parallel computation resulting in considerable improvement in searching efficiency. Simulated results of the design of a buck regulator with the proposed approach were verified with experimental results from the actual hardware implementation. It showed that the design with the proposed scheme was compatible with the design specification.