Perturbation approach applied to modal diffraction methods

Eigenvalue computation is an important part of many modal diffraction methods, including the rigorous coupled wave approach (RCWA) and the Chandezon method. This procedure is known to be computationally intensive, accounting for a large proportion of the overall run time. However, in many cases, eigenvalue information is already available from previous calculations. Some of the examples include adjacent slices in the RCWA, spectral- or angle-resolved scans in optical scatterometry and parameter derivatives in optimization. In this paper, we present a new technique that provides accurate and highly reliable solutions with significant improvements in computational time. The proposed method takes advantage of known eigensolution information and is based on perturbation method.     

Transport modulation in Ge/Si core/shell nanowires through controlled synthesis of doped Si shells

Appropriately controlling the properties of the Si shell in Ge/Si core/shell nanowires permits not only passivation of the Ge surface states, but also introduces new interface phenomena, thereby enabling novel nanoelectronics concepts. Here, we report a rational synthesis of Ge/Si core/shell nanowires with doped Si shells. We demonstrate that the morphology and thickness of Si shells can be controlled for different dopant types by tuning the growth parameters during synthesis. We also present distinctly different electrical characteristics that arise from nanowire field-effect transistors fabricated using the synthesized Ge/Si core/shell nanowires with different shell morphologies. Furthermore, a clear transition in the modification of device characteristics is observed for crystalline shell nanowires following removal of the shell using a unique trimming process of successive native oxide formation/etching. Our results demonstrate that the preferred transport path through the nanowire structure can be modulated by appropriately tuning the growth conditions.     

Engineering, characterization and directional self-assembly of anisotropically modified nanocolloids

Along with traditional attributes such as the size, shape, and chemical structure of polymeric micro-objects, control over material distribution, or selective compartmentalization, appears to be increasingly important for maximizing the functionality and efficacy of biomaterials. The fabrication of tri- and tetracompartmental colloids made from biodegradable poly(lactide-co-glycolide) polymers via electrohydrodynamic co-jetting is demonstrated. The presence of three compartments is confirmed via flow cytometry. Additional chemical functionality is introduced via the incorporation of acetylene-functionalized polymers into individual compartments of the particles. Direct visualization of the spatioselective distribution of acetylene groups is demonstrated by confocal Raman microscopy as well as by reaction of the acetylene groups with azide-biotin via 'click chemistry'. Biotin-streptavidin binding is then utilized for the controlled assembly and orientation of bicompartmental particles onto functionalized, micropatterned substrates prepared via chemical vapor deposition polymerization.     

Direct Protein Detection in the Sample Solution by Monitoring Rotational Dynamics of Nickel Nanorods

The feasibility of a recently introduced homogeneous immunodiagnostic approach to directly detect analyte binding by optical observation of the hydrodynamic properties of magnetically rotated nanorods (“PlasMag”) is demonstrated experimentally. Specifically, it is shown that the phase lag of the long axis of nickel nanorods (magnetic core parameters: length 182 nm, diameter 26 nm) with respect to externally applied rotating magnetic fields significantly increases on the adhesion of bovine serum albumin (BSA) protein to their surfaces. To validate these results, the amount of bound protein molecules is independently determined by analysis of the electrophoretic mobility of the nanorods. Furthermore, the data also demonstrate the applicability of recently developed empirical models based on numerical solutions of the Fokker‐Planck equation for describing the dynamics of magnetic nanoparticles in rotating magnetic fields.     

Recent Progress in Preparing Nonwoven Nanofibers via Needleless Electrospinning

Electrospinning has received a lot of attention in recent years because it can create nonwoven nanofiber webs with high surface area and porosity. However, the typical needle and syringe-based electrospinning systems feature poor productivity that has limited their usefulness in the industrial field. Here, current developments in the creation of nanofibers employing nonconventional electrospinning methods, such as needleless electrospinning and syringeless electrospinning, are examined. These alternate electrospinning techniques, which are dependent on numerous polymer droplets of varied shapes, have the potential to match the productivity required for industry-scale manufacturing of nanofibers. Additionally, they make it possible to produce nanofibers that are difficult to spin using traditional techniques, like electrospinning of colloidal suspensions.     

Solution of a Groundwater Control Problem with Implicit Filtering

In this paper we describe the application of a parallel implementation of the implicit filtering algorithm to a control problem from hydrology. We seek to control the temperature at a group of drinking water wells by placing barrier wells between the drinking water wells and a well that injects heated water from an industrial site.     

Study of the uncertainties due to position change of the PWR aeroball measurement system

The aeroball measurement system (AMS) is an important in-core instrumentation in German pressurized water reactors. Therefore, it is essential to know the possible uncertainties of this system. One is the lack of knowledge of the positions of balls in the guide tubes. The position changes can be up to 7 mm. Since the neutron flux distribution is not constant across the guide tubes, different reaction rates can result from the displacements. Both fuel assembly and full core calculations were carried out with the Monte Carlo code MCNP5. Differences in the reaction rates of up to 2% could be determined. In most cases, differences are only up to 0.5%. The results were hardly influenced by burnup and boron concentration in the water moderator. For fuel assemblies containing gadolinium as a burnable poison, a more pronounced reduction could be observed in the direction towards the gadolinium fuel rods. Overall, it was found that the AMS measurement values are very robust with regard to possible variations of ball positions.     

Liver TAG Transiently Decreases While PL n-3 and n-6 Fatty Acids are Persistently Elevated in Insulin Resistant Mice

Changes in fatty acid metabolism associated with insulin resistance have been described in rats and humans but have not been well characterized in the frequently used mouse model of diet-induced obesity. To analyse the early phase as well as established insulin resistance, C57BL/6 mice were placed for 1 or 16 weeks on a high fat diet (1w-HFD, 16w-HFD). Endocrine and metabolic parameters indicated that 1w-HFD mice showed a moderate but significant induction of insulin resistance while 16w-HFD mice exhibited profound obesity-associated insulin resistance and dyslipidemias. Significant alterations in fatty acid composition were observed in plasma and liver in both groups. Liver phospholipid-associated arachidonate and docosahexaenoate were increased in both 1w-HFD and 16w-HFD mice, possibly due to increased expression of the desaturases Fads1 and Fads2. Unexpectedly, SCD1 activity and gene expression in liver were decreased in the 1w-HFD group accompanied by diminished total hepatic lipid levels, while they were increased in chronically fed mice. Our data indicate that the early phase of HFD-induced insulin resistance is not associated with elevated liver lipid concentration. Furthermore, the early and persistent rise of arachidonate and docosahexaenoate indicates that insulin resistance is not due to insufficient availability (or concentrations) of polyunsaturated fatty acids as postulated previously. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.