Forward and Reverse Converters and Moduli Set Selection in Signed-Digit?Residue?Number?Systems

This paper presents an investigation into using a combination of two alternative digital number representations; the residue number system (RNS) and the signed-digit (SD) number representation in digital arithmetic circuits. The combined number system is called RNS/SD for short. Since the performance of RNS/SD arithmetic circuits depends on the choice of the moduli set (a set of pairwise prime numbers), the purpose of this work is to compare RNS/SD number systems based on different sets. Five specific moduli sets of different lengths are selected. Moduli-set-specific forward and reverse RNS/SD converters are introduced for each of these sets. A generic conversion technique for moduli sets consisting of any number of elements is also presented. Finite impulse response (FIR) filters are used as reference designs in order to evaluate the performance of RNS/SD processing. The designs are evaluated with respect to delay and circuit area in a commercial 0.13 μm CMOS process. For the case of FIR filters it is shown that generic moduli sets with five or six moduli results in designs with the best area × delay products.

Single Filter Frequency Masking High-Speed Recursive Digital Filters

For recursive filter the maximal sample frequency is bounded by the recursive loops in the filter. [In this paper, it is understood that recursive filters are infinite-length impulse response (IIR) filters.] In this work, a filter structure based on the use of the frequency masking approach is presented that increases the maximal sample frequency for narrowband and wideband filters by introducing more delay elements in the recursive loops. By using identical subfilters (except for the periods), the subfilters can be mapped using folding to a single pipeline/interleaved arithmetic structure yielding an area-efficient implementation. The filters are potentially suitable for low-power implementation by using power supply voltage scaling techniques. In this work, the design of the filters is discussed and estimations of the ripples are derived. Two examples show the viability of the proposed method.     

Lead and cadmium in tissues from horse, sheep, lamb and reindeer in Sweden

 Levels of lead and cadmium were determined in tissues of muscle, liver and kidney from horse, lamb, sheep and reindeer in Sweden during the years 1994–1997. Mean levels of lead in muscle, liver and kidney from horse were <0.002, 0.13 and 0.047, from lamb <0.002, 0.031 and 0.053, from sheep <0.002, not analysed and 0.046, and from reindeer 0.003, 0.13 and 0.13 mg/fresh weight, respectively. The mean levels of cadmium in muscle, liver and kidney from horse were 0.042, 2.5 and 18, from lamb 0.0019, 0.031 and 0.12, from sheep 0.0034, not analysed and 1.0, and from reindeer 0.003, 0.60 and 2.7 mg/fresh weight, respectively. Comparisons with literature data were attempted. In some cases the results could differ by several orders of magnitude. It cannot be ruled out that some of the differences between studies might be due to analytical differences, making comparisons very difficult. Received: 2 June 1998     

Apparent chemical composition of nine commercial or semi-commercial whey protein concentrates, isolates and fractions

Summary Analytical results are given for whey powders prepared on a commercial or semi-commercial scale by three companies. Altogether, five preparations enriched in β-lactoglobulin, four whey protein isolates and a fraction enriched in α-lactalbumin were analyzed for protein composition, including %β-lactoglobulin, α-lactalbumin, bovine serum albumin, casein (glyco) macropeptide and the main triglycerides. Protein composition was determined by high pressure gel permeation and reversed phase liquid chromatography and by capillary zone electrophoresis. The extent of modification of the native β-lactoglobulin structure was also measured through the degree of lactosylation and the fraction of accessible free sulphydryl groups. One significant finding was that the calculated recovery of protein following quantitation of the chromatogram or electropherogram was seldom above 90% and occasionally below 60% of that loaded onto the column or capillary, raising doubts as to the reliability of the analytical results. Extrapolation by linear regression to 100% recovery allowed estimates to be made of the true β-lactoglobulin composition of the samples. The nine samples could be placed into three distinct groups with estimated true β-lactoglobulin weight % of 70.9 ± 1.1, 62.0 ± 3.4 and 39.5 ± 4.9. Physico-chemical properties of the group of samples are reported elsewhere (Holt et al ., 1999).     

Metal-Organic Framework Thin Films Grown on Functionalized Graphene as Solid-State Ion-Gated FETs

The unique properties of 2D-materials like graphene are exploited in various electronic devices. In sensor applications, graphene shows a very high sensitivity, but only a low specificity. This shortcoming can be mastered by using heterostructures, where graphene is combined with materials exhibiting high analyte selectivities. Herein, this study demonstrates the precise deposition of nanoporous metal-organic frameworks (MOFs) on graphene, yielding bilayers with excellent specificity while the sensitivity remains large. The key for the successful layer-by-layer deposition of the MOF films (SURMOFs) is the use of planar polyaromatic anchors. Then, the MOF pores are loaded with ionic liquid (IL). For functioning sensor devices, the IL@MOF films are grown on graphene field-effect transistors (GFETs). Adding a top-gate electrode yields an ion-gated GFET. Analysis of the transistor characteristics reveals a clear Dirac point at low gate voltages, good on-off ratios, and decent charge mobilities and densities in the graphene channel. The GFET-sensor reveals a strong and selective response. Compared to other ion-gated-FET devices, the IL@MOF material is relatively hard, allowing the manufacturing of ultrathin devices. The new MOF-anchoring strategy offers a novel approach generally applicable for the functionalization of 2D-materials, where MOF/2D-material hetero-bilayers carry a huge potential for a wide variety of applications.     

Enhancing the Selectivity and Transparency of the Electron Contact in Silicon Heterojunction Solar Cells by Phosphorus Catalytic Doping

An intrinsic hydrogenated amorphous silicon (a-Si:H(i)) film and a doped silicon film are usually combined in the heterojunction contacts of silicon heterojunction (SHJ) solar cells. In this work, a post-doping process called catalytic doping (Cat-doping) on a-Si:H(i) is performed on the electron selective side of SHJ solar cells, which enables a device architecture that eliminates the additional deposition of the doped silicon layer. Thus, a single phosphorus Cat-doping layer combines the functions of two other layers by enabling excellent interface passivation and high carrier selectivity. The overall thinner layer on the window side results in higher spectral response at short wavelengths, leading to an improved short-circuit current density of 40.31 mA cm⁻² and an efficiency of 23.65% (certified). The cell efficiency is currently limited by sputter damage from the subsequent transparent conductive oxide fabrication and low carrier activation in the a-Si:H(i) with Cat-doping. Numerical device simulations show that the a-Si:H(i) with Cat-doping can provide sufficient field effect passivation even at lower active carrier concentrations compared to the as-deposited doped layer, due to the lower defect density.     

Cryptanalysis of MD2

This paper considers the hash function MD2 which was developed by Ron Rivest in 1989. Despite its age, MD2 has withstood cryptanalytic attacks until recently. This paper contains the state-of-the-art cryptanalytic results on MD2, in particular collision and preimage attacks on the full hash function, the latter having complexity 2⁷³, which should be compared to a brute-force attack of complexity 2¹²⁸.     

Design of Engineered Elastomeric Substrate for Stretchable Active Devices and Sensors

In the field of flexible electronics, emerging applications require biocompatible and unobtrusive devices, which can withstand different modes of mechanical deformation and achieve low complexity in the fabrication process. Here, the fabrication of a mesa‐shaped elastomeric substrate, supporting thin‐film transistors (TFTs) and logic circuits (inverters), is reported. High‐relief structures are designed to minimize the strain experienced by the electronics, which are fabricated directly on the pillars' surface. In this design configuration, devices based on amorphous indium‐gallium‐zinc‐oxide can withstand different modes of deformation. Bending, stretching, and twisting experiments up to 6 mm radius, 20% uniaxial strain, and 180° global twisting, respectively, are performed to show stable electrical performance of the TFTs. Similarly, a fully integrated digital inverter is tested while stretched up to 20% elongation. As a proof of the versatility of mesa‐shaped geometry, a biocompatible and stretchable sensor for temperature mapping is also realized. Using pectin, which is a temperature‐sensitive material present in plant cells, the response of the sensor shows current modulation from 13 to 28 °C and functionality up to 15% strain. These results demonstrate the performance of highly flexible electronics for a broad variety of applications, including smart skin and health monitoring.     

Enhanced performance in the deteriorated area of multicrystalline silicon wafers by internal gettering

The deteriorated area of the multicrystalline silicon (mc‐Si) ingots grown by directional solidification, commonly known as the Red Zone, is usually removed before wafering. This area, characterized by poor minority carrier lifetime, is located on the sides, at the top, and the bottom of the mc‐Si ingots. In this study, the effect of internal gettering by oxygen precipitates and structural defects has been investigated on the bottom zone of a mc‐Si ingot. Nucleation and growth of oxygen precipitates as well as low temperature annealing were studied. Photoluminescence imaging, lifetime mapping, and interstitial iron measurements performed by μ‐PCD reveal a considerable reduction of the bottom Red Zone. An improvement of lifetime from below 1 µs to about 20 µs and a reduction of interstitial iron concentration from 1.32 × 10¹³ at/cm³ to 8.4 × 10¹⁰ at/cm³ are demonstrated in this paper. Copyright © 2013 John Wiley & Sons, Ltd.     

Antibacterial Surface Coatings from Zinc Oxide Nanoparticles Embedded in Poly(N‐isopropylacrylamide) Hydrogel Surface Layers

Despite multiple research approaches to prevent bacterial colonization on surfaces, device‐associated infections are currently responsible for about 50% of nosocomial infections in Europe and significantly increase health care costs, which demands development of advanced antibacterial surface coatings. Here, novel antimicrobial composite materials incorporating zinc oxide nanoparticles (ZnO NP) into biocompatible poly(N‐isopropylacrylamide) (PNIPAAm) hydrogel layers are prepared by mixing the PNIPAAm prepolymer with ZnO NP, followed by spin‐coating and photocrosslinking. Scanning electron microscopy (SEM) characterization of the composite film morphology reveals a homogeneous distribution of the ZnO NP throughout the film for every applied NP/polymer ratio. The optical properties of the embedded NP are not affected by the matrix as confirmed by UV‐vis spectroscopy. The nanocomposite films exhibit bactericidal behavior towards Escherichia coli (E. coli) for a ZnO concentration as low as ≈0.74 μg cm^?2 (1.33 mmol cm^?3), which is determined by inductively coupled plasma optical emission spectrometry. In contrast, the coatings are found to be non‐cytotoxic towards a mammalian cell line (NIH/3T3) at bactericidal loadings of ZnO over an extended period of seven days. The differential toxicity of the ZnO/hydrogel nanocomposite thin films between bacterial and cellular species qualifies them as promising candidates for novel biomedical device coatings.