Evaluation of the hot-carrier-induced offset voltage of differential pairs in analogue CMOS circuits

Using a specifically developed measurement set-up and a test structure typical for analogue applications, high precision measurements of the stress-induced offset voltage degradation of differential pairs are presented. Extrapolation to operating conditions yields valuable information for analogue design in the sub-micron CMOS regime.     

Diabetes insipidus and panhypopituitarism in an 8-year-old girl due to probable lymphocytic hypophysitis

A 43-year-old white man with a history of cigarette smoking, hypertension, nephrolithiasis, and cervical degenerative arthritis was hospitalized for sudden-onset severe, substernal, and pleuritic chest pain with epigastric radiation. Despite evaluation, the cause remained unclear and the patient expired on hospital day 5. Autopsy revealed acute Stanford type A aortic dissection, hemopericardium, and hemothorax. Grossly, the aorta and its branches, including uninvolved medium-sized arteries, displayed extreme mural fragility. Microscopic examination showed a primary lymphoplasmacytic aortitis-periaortitis without giant cells. Rents within the tunica media, medial-adventitial inflammation, and elastic fiber disruption were limited to sites of gross aortic dissection. Muscular arteries showed patchy, chronic arteritis-periarteritis without giant cell infiltrate or aneurysm formation. This case documents an unusual association of primary lymphoplasmacytic aortitis and aortic dissection.     

Boundary Treatment and Multigrid Preconditioning for Semi-Lagrangian Schemes Applied to Hamilton–Jacobi–Bellman Equations

We analyse two practical aspects that arise in the numerical solution of Hamilton–Jacobi–Bellman equations by a particular class of monotone approximation schemes known as semi-Lagrangian schemes. These schemes make use of a wide stencil to achieve convergence and result in discretization matrices that are less sparse and less local than those coming from standard finite difference schemes. This leads to computational difficulties not encountered there. In particular, we consider the overstepping of the domain boundary and analyse the accuracy and stability of stencil truncation. This truncation imposes a stricter CFL condition for explicit schemes in the vicinity of boundaries than in the interior, such that implicit schemes become attractive. We then study the use of geometric, algebraic and aggregation-based multigrid preconditioners to solve the resulting discretised systems from implicit time stepping schemes efficiently. Finally, we illustrate the performance of these techniques numerically for benchmark test cases from the literature.     

A zeolite family with chiral and achiral structures built from the same building layer

Porosity and chirality are two of the most important properties for materials in the chemical and pharmaceutical industry. Inorganic microporous materials such as zeolites have been widely used in ion-exchange, selective sorption/separation and catalytic processes. The pore size and shape in zeolites play important roles for specific applications. Chiral inorganic microporous materials are particularly desirable with respect to their possible use in enantioselective sorption, separation and catalysis. At present, among the 179 zeolite framework types reported, only three exhibit chiral frameworks. Synthesizing enantiopure, porous tetrahedral framework structures represents a great challenge for chemists. Here, we report the silicogermanates SU-32 (polymorph A), SU-15 (polymorph B) (SU, Stockholm University) and a hypothetical polymorph C, all built by different stacking of a novel building layer. Whereas polymorphs B and C are achiral, each crystal of polymorph A exhibits only one hand and has an intrinsically chiral zeolite structure. SU-15 and SU-32 are thermally stable on calcination.     

Amperometric response from the glycolytic versus the pentose phosphate pathway in Saccharomyces cerevisiae cells

The two main metabolic pathways involved in sugar metabolism, i.e., the pentose phosphate pathway (PPP) and the glycolytic pathway (GP), were amperometrically monitored using a double-mediator system composed of menadione and ferricyanide. With the use of the Saccharomyces cerevisiae deletion mutant, EBY44, lacking the gene encoding for the branch point enzyme phosphoglucose isomerize, selective amperometric monitoring of the PPP, mainly producing NADPH, and the GP, mainly producing NADH, could be achieved. It was found that the bioelectrocatalytic current was primarily originating from NADPH. This conclusion was supported by metabolite flux analysis, confirming that, in the presence of menadione, the cells increase the rate of NADPH-producing reactions although these processes might be detrimental to cell survival. The higher rate of in vivo NADPH-dependent menadione reduction can be ascribed to the fact that the intracellular NADPH/NADP(+) ratio is much higher than NADH/NAD(+) as well as that the former ratio is more tightly controlled. This tight control over the cofactor ratios is lost upon cell disintegration as observed from spectrophotometric assays using crude cell extract, and amperometric investigations of permeabilized cells indicate a higher rate of NADH- than NADPH-dependent menadione reduction. These in vitro experiments show a higher activity of NADH-dependent than NADPH-dependent menadione-reducing dehydrogenases in S. cerevisiae cells.     

Red, green and blue lasing enabled by single-exciton gain in colloidal quantum dot films

Colloidal quantum dots exhibit efficient photoluminescence with widely tunable bandgaps as a result of quantum confinement effects. Such quantum dots are emerging as an appealing complement to epitaxial semiconductor laser materials, which are ubiquitous and technologically mature, but unable to cover the full visible spectrum (red, green and blue; RGB). However, the requirement for high colloidal-quantum-dot packing density, and losses due to non-radiative multiexcitonic Auger recombination, have hindered the development of lasers based on colloidal quantum dots. Here, we engineer CdSe/ZnCdS core/shell colloidal quantum dots with aromatic ligands, which form densely packed films exhibiting optical gain across the visible spectrum with less than one exciton per colloidal quantum dot on average. This single-exciton gain allows the films to reach the threshold of amplified spontaneous emission at very low optical pump energy densities of 90?μJ?cm(-2), more than one order of magnitude better than previously reported values. We leverage the low-threshold gain of these nanocomposite films to produce the first colloidal-quantum-dot vertical-cavity surface-emitting lasers (CQD-VCSEL). Our results represent a significant step towards full-colour single-material lasers.     

Moth‐eye antireflection coating fabricated by nanoimprint lithography on 1 eV dilute nitride solar cell

We report on the performance of biomimicked antireflection coating applied to dilute nitride solar cell. The coating consists of nanostructures replicating the moth‐eye geometry and has been fabricated by nanoimprint lithography directly within the window layer covering the dilute nitride absorbing junction. The mean reflectivity within the spectral range of 320–1800 nm remains under 5% for incident angles up to 45°. The effect of the coating on the cell performance was assessed by measuring the current–voltage characteristics under simulated solar illumination. A clear performance increase was identified when comparing a solar cell with the moth‐eye coating with a solar cell having a standard SiN_x/SiO₂ coating. Copyright © 2012 John Wiley & Sons, Ltd.