Extremely low back facet feedback by quantum-confined Stark effectabsorption in an edge-emitting light-emitting diode

The quantum-confined Stark effect is employed to form an integral reverse-biased absorber in a GaInAsP edge-emitting light-emitting diode. Optical low coherence reflectometry is used to measure the magnitude of reflections through this absorber. Front-facet-back-facet roundtrip reflection magnitudes are below -110 dB in devices having an antireflection coating on the front facet only. All other round trip reflections are below -80 dB. This device provides a wide usable dynamic range in optical low coherence reflectometry measurements     

Evanescent amplification in a single-mode optical fibre

By replacing a portion of the cladding of a single-mode fibre with a laser dye, amplification can be achieved by means of an evanescent field interaction. External gains as high as 22 dB have been measured by guiding both a pulsed pump and CW signal within the single-mode fibre.     

Electron trapping in irradiated SIMOX buried oxides

Presented are new results of X-ray exposure of silicon-on-insulator devices fabricated on SIMOX (separation by implantation of oxygen) substrates. It is shown that the presence of numerous electron traps in the buried oxide may dominate the back-gate threshold voltage shift of strongly irradiated SIMOX transistors. A rebound effect occurs under a negative oxide field, due to the trapping of negative charges rather than to interface states generation. Irradiated transistors also show an increased sensitivity to hot-carrier effects     

Isovaleric acidemia. Study and treatment in 3 brothers

The cases of 3 sibs presenting with isovaleric acidemia are reported. The first infant died when he was 9 day-old. The two others appear to have benefited from a controlled leucine diet which was introduced from the first days on of life. The clinical symptomatology, highly typical of the disease, is described. Diagnosis was not assessed on amino-acids chromatography but on the chromatography of volatile fatty acids. The mode of treatment is described: peritoneal dialysis, with the object of rounding a crucial cape, and overall controlled leucine diet, but supplemented by essential amino-acids.     

Dynamics and control of a biodiesel process by reactive absorption

Integrated biodiesel processes based on reactive separations powered by solid acid/base catalysts are available nowadays, offering significant advantages such as minimal capital investment and operating costs, as well as no catalyst-related waste streams and no soap formation. However, the controllability of the process is just as important as the capital and operating savings. In such processes the small number of degrees of freedom is a drawback which makes it difficult to correctly set the ratio of reactant feeds and consequently to avoid impurities in the products. This work considers the process control of biodiesel production by reactive absorption, the main result being an efficient control structure that ensures the excess of methanol that is necessary for the total conversion of the fatty acids and for prevention of the difficult separations, while maintaining high purity of the water by-product. Rigorous simulations were performed - using Aspen Plus and Aspen Plus Dynamics as efficient computer-aided process engineering tools - for a plant producing 10 ktpy biodiesel from waste vegetable oil with high free fatty acids content, using solid acids as green catalysts. This reactive absorption process eliminates all conventional catalyst-related operations, and efficiently uses the raw materials and the reactor volume in an integrated setup that is well controllable in spite of the reduced number of degrees of freedom.     

Comparison of low-temperature electrical characteristics of gate-all-around nanowire FETs, Fin FETs and fully-depleted SOI FETs

Low-temperature electrical characteristics of n-type gate-all-around vertically-stacked silicon nanowire (SNW) field-effect transistors (FETs) with high-k/metal gate have been investigated and are compared to those with Fin and fully-depleted silicon-on-insulator (FD SOI) FETs. In particular, the effective electron mobilities behaviors are discussed. Nanowires with a rectangular cross section of 15 nm in width and 19 nm in height have shown a strongly degraded mobility as compared to those with Fin and FD SOI FETs. Low-temperature measurements have revealed that the mobility degradation is due to higher surface-roughness limited mobility. On the other hand, no significant difference in the interface trap densities among the kinds of FETs measured in the study have been observed from the temperature dependence in the subthreshold slope.