Disruptive infrared image sensors enabled by quantum dots

Sensors based on quantum dot photodiodes promise quality and accessibility improvement of infrared imaging. We demonstrate miniaturization by sub-2-μm pixel pitch arrays. Functionality is confirmed with external quantum efficiencies above 40% at 1450 nm. Monolithic integration enables high throughput and wide deployment of short-wave infrared (SWIR) imagers in applications that previously could not afford them.     

A SAT-based preimage analysis of reduced Keccak hash functions

In this paper, we present a preimage attack on reduced versions of Keccak hash functions. We use our recently developed toolkit CryptLogVer for generating the conjunctive normal form, CNF, which is passed to the SAT solver PrecoSAT. We found preimages for some reduced versions of the function and showed that full Keccak function has a comfortable security margin against this kind of attack.     

Positron implantation profiles in layered samples

The paper presents theoretical and experimental studies of the positron implantation profiles in layered samples. The Monte Carlo simulations performed using the GEANT4 toolkit reveal accumulation of positrons in the denser layer embedded between two less dense layers. That effect is significant not only for low energy positrons at slow monoenergetic positron beams but also for high energy positrons which are emitted from radioactive nuclei in conventional experiments. Measurements of the positron implantation profile into the samples which consist of silver and aluminium foils of different thickness show profile features which correspond well with those simulated by the GEANT4 toolkit for examined cases. We propose to call this phenomenon the accumulation effect of energetic positrons.     

Alternative crystal field parameters for rare-earth ions obtained from various techniques: I. Reanalysis of Mössbauer spectroscopy studies of Tm3+ ions in TmBa2Cu4O8 and TmBa2Cu3O7−δ high Tc superconductors

In this series of papers, implications of two major properties of orthorhombic crystal field (CF) Hamiltonians for interpretation of CF data for rare-earth ions obtained from various experimental techniques are considered. These properties, i.e. existence of alternative (physically equivalent) CF parameter (CFP) sets and incorrectness of comparison of such alternative yet disparate CFP sets, appear not fully utilized in literature. The CFP sets for Tm³⁺ in orthorhombic high T_c superconductors TmBa₂Cu₄O₈ and TmBa₂Cu₃O_7?δ are reanalysed applying standardization and closeness of CFP sets. Correlated CFP sets are transformed to the same nominal standard axis system. Standardization transformations are used to generate alternative (standard and non-standard) CFP sets, which may be utilized in the multiple correlated fitting technique to improve reliability of final fitted CFPs. The discrepancies concerning orthorhombic CFPs, identified in Mössbauer spectroscopy studies of Tm³⁺ ion in TmBa₂Cu₄O₈, are clarified. Misinterpretations of CF and structural data arising from usage of intrinsically incomparable CFP sets for similar ion–host systems are discussed.     

A note on t-complementing permutations for graphs

In this note we present a necessary and sufficient condition for a permutation to be t-complementing which is a natural generalization of the well-known result concerning self-complementing permutations.     

pH/organic solvent double-gradient reversed-phase HPLC

A new reversed-phase high-performance liquid chromatographic (RP HPLC) procedure has been theoretically and experimentally established. The approach consists of the simultaneous development of a gradient of pH and of the organic modifier in the mobile phase. The proposed theoretical model of the pH/organic solvent double-gradient RP HPLC allows determination of both pK(a) and the lipophilicity parameter of the ionized and the nonionized form of the analyte and prediction of the retention times at specific separation conditions as well as bandwidth for all analytes. The model provides a rational basis for optimization of separation of ionizable analytes at any given chromatographic mode and analysis conditions. In addition, in the case of pH/organic solvent double-gradient RP HPLC, a compression of analyte peak and its reduced tailing can be expected.     

Improving the performance properties of valve martensitic steel by glow discharge-assisted nitriding

The paper presents the results of examinations of the microstructure and performance properties of martensitic steel martensitic steel subjected to glow discharge-assisted nitriding. The effects of the process temperature and the chemical composition of the gaseous atmosphere on the microhardness, corrosion resistance and frictional wear resistance were examined. It has been found that glow discharge nitriding increases the microhardness of the steel and improves significantly its frictional wear resistance.     

Fixed point method for autonomous on-line neural network training

This paper considers on-line training of feedforward neural networks. Training examples are only available through sampling from a certain, possibly infinite, distribution. In order to make the learning process autonomous, one can employ Extended Kalman Filter or stochastic steepest descent with adaptively adjusted step-sizes. Here the latter is considered. A scheme of determining step-sizes is introduced that satisfies the following requirements: (i) it does not need any auxiliary problem-dependent parameters, (ii) it does not assume any particular loss function that the training process is intended to minimize, (iii) it makes the learning process stable and efficient. An experimental study with several approximation problems is presented. Within this study the presented approach is compared with Extended Kalman Filter and LFI, with satisfactory results.     

Effect of amaranth seeds in diet on oxidative status in plasma and selected tissues of high fructose-fed rats

The aim of this study was to assess the influence of amaranth seeds in different doses, under conditions of oxidative stress induced by dietary fructose, on antioxidant status of selected rat tissues, erythrocytes and plasma. Fructose administration caused oxidative stress that was manifested by the increase in plasma malondialdehyde and by the decrease in the enzymatic antioxidant activity. Co-administration of amaranth seeds influenced the oxidative stress, as was evidenced by decreasing malondialdehyde in plasma and changing the activities of antioxidant enzymes (erythrocyte superoxide dismutase, catalase, and plasma glutathione peroxidase). Our findings demonstrate that amaranth seeds can act as a moderate protective agent against fructose-induced changes. Our results suggest that the antioxidative system of plasma, heart and lungs is more efficient when amaranth seeds are present in the diet.     

Assessment of InfiniteFocus system measurement errors in testing the accuracy of crown and tooth body model

Journal of Mechanical Science and Technology - The paper aims to analyze the InfiniteFocus system for the capability to measure macrogeometry of tooth models manufactured using two material...