Analytical study of diffraction effects in extremely large segmented telescopes

We present an analysis of the diffraction effects from a segmented aperture with a very large number of segments-prototype of the next generation of extremely large telescopes. This analysis is based on the point-spread-function analytical calculation for Keck-type hexagonal segmentation geometry. We concentrate on the effects that lead to the appearance of speckles and/or a regular pattern of diffraction peaks. These effects are related to random piston and tip-tilt errors on each segment, gaps between segments, and segment edge distortion. We deliver formulas and the typical numerical values for the Strehl ratio, the relative intensity of higher-order diffraction peaks, and the averaged intensity of speckles associated with each particular case of segmentation error.     

Direct spectral measurements with a Brewer spectroradiometer: absolute calibration and aerosol optical depth retrieval

We present three different methods for the absolute calibration of direct spectral irradiances measured with a Brewer spectroradiometer, which are shown to agree to within +/- 2%. Direct irradiance spectra derived by Brewer and Bentham spectroradiometers agree to within 4 +/- 3%. Good agreement was also found by a comparison of the aerosol optical depth and Angstrom exponent retrieved by the two instruments and a multifilter rotational shadowband radiometer. The spectral aerosol optical depth (300-365 nm) derived from six years of direct irradiance measurements at Thessaloniki shows a distinct seasonal variation, averaging to approximately 0.3 at 340 nm in winter and approximately 0.7 in summer.     

Study of absorption and reflection in solid-state random laser media

Comparing the absorption spectrum of a single-crystalline material and the reflection spectrum of its powder, we have derived a simple empirical formula for the reflection coefficient of absorbing powder. The proposed equation, which slightly resembles the Lambert-Beer law for transmission, does not correspond to the equation derived in the approximation of a simple one-dimensional diffusion model.     

Quantification of etoposide and etoposide phosphate in human plasma by micellar electrokinetic chromatography and near-field thermal lens detection

A method employing micellar electrokinetic chromatography in combination with near-field thermal lens detection (NF-TLD) was developed for the rapid simultaneous determination of etoposide phosphate and etoposide in human blood plasma, taking teniposide as internal standard. The method developed allows the baseline separation of the solutes of interest from each other and from potential interfering matrix constituents within 4 min. The NF-TLD device employed permits detection of solutes absorbing electromagnetic radiation at lambda = 257 nm in fused-silica capillaries with 75-microm i.d. via the near-field thermal lens effect with LODs of 100 microg L(-1) for etoposide phosphate and 170 microg L(-1) for etoposide. Comparison of the performance of this detector to the performance of a commercial absorption spectrometric detector working at lambda = 257 nm showed a substantial improvement in detection limits (up to 60-fold improvement) for the near-field thermal lens detector.     

Truncated aspartate aminotransferase from alkalophilic Bacillus circulans with deletion of N-terminal 32 amino acids is a non-functional monomer in a partially structured state

Aspartate aminotransferase (AspAT) from alkalophilic Bacilluscirculans contains an additional N-terminal sequence of 32 aminoacid residues that are absent in all other AspATs from differentsources. Modeling suggested that this sequence forms two -helicalsegments which establish a continuous network of interactionson the surface of the molecule. In the present study, we studiedthe role of the N-terminal sequence in folding and stabilityof AspAT by applying the scanning calorimetry, and CD and fluorescencespectroscopies to the native and truncated enzymes. TruncatedAspAT (2 mutant) devoid of N-terminal residues cannot providesufficient potential of quaternary intersubunit and subunit-cofactorinteractions, which results in a monomeric non-functional conformation.However, the residual tertiary interactions in the 2 mutantare sufficient to: i) provide stability of a residual structureover a wide pH range; ii) confer moderate cooperativity of thedenaturant-induced transition while only low cooperativity ofthe thermal transition, and iii) maintain the hydrophobic coreof a part of the structure which prevents aromatic fluorophoresfrom quenching by water. Furthermore, the present study providesevidence that AspAT from the alkalophilic bacterium followsunfolding pathway comprising a stable non-functional intermediate,in contrast to a two-state mechanism of the thermophilic AspATfrom Sulfolobus solfataricus.     

Cognitive dissonance.

This article reviews critically the experimental evidence in support of cognitive dissonance theory as applied to complex social events. The criticisms which can be made of this literature fall into 2 main classes. 1st, the experimental manipulations are usually so complex and the crucial variables so confounded that no valid conclusions can be drawn from the data. 2nd, a number of fundamental methodological inadequacies in the analysis of results—as, e.g., rejection of cases and faulty statistical analysis of the data—vitiate the findings. As a result, one can only say that the evidence adduced for cognitive dissonance theory is inconclusive. Suggestions are offered for the methodological improvement of studies in this area. The review concludes with the thesis that the most attractive feature of cognitive dissonance theory, its simplicity, is in actual fact a self-defeating limitation. (44 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A new technology for microfluidic structures preparation based on a photoimageable ceramic

A new method for fabrication of hybrid ceramic-polymer structures with diversified geometry of microchannel was elaborated. This method is universal, non-complicated, and utilises commercially available materials and basic equipment for thick film technology and photolithography. A microchip for capillary electrophoresis was prepared as an example of microfluidic structure fabrication. The chip was prepared by using a photosensitive paste (dielectric FODEL 6050) which was screen printed onto a ceramic substrate, exposed through an appropriate mask, developed, fired and then glazed. In this way, we obtained the structure which can be bonded with poly(dimethylsiloxane) PDMS after oxygen plasma treatment. The application of transparent PDMS as a seal of the microchannel enabled the optical detection.     

Altered Metabolism in Glioblastoma: Myeloid-Derived Suppressor Cell (MDSC) Fitness and Tumor-Infiltrating Lymphocyte (TIL) Dysfunction

The metabolism of glioblastoma (GBM), the most aggressive and lethal primary brain tumor, is flexible and adaptable to different adverse conditions, such as nutrient deprivation. Beyond glycolysis, altered lipid metabolism is implicated in GBM progression. Indeed, metabolic subtypes were recently identified based on divergent glucose and lipid metabolism. GBM is also characterized by an immunosuppressive microenvironment in which myeloid-derived suppressor cells (MDSCs) are a powerful ally of tumor cells. Increasing evidence supports the interconnection between GBM and MDSC metabolic pathways. GBM cells exert a crucial contribution to MDSC recruitment and maturation within the tumor microenvironment, where the needs of tumor-infiltrating lymphocytes (TILs) with antitumor function are completely neglected. In this review, we will discuss the unique or alternative source of energy exploited by GBM and MDSCs, exploring how deprivation of specific nutrients and accumulation of toxic byproducts can induce T-cell dysfunction. Understanding the metabolic programs of these cell components and how they impact fitness or dysfunction will be useful to improve treatment modalities, including immunotherapeutic strategies.     

Activity of CdTe Quantum-Dot-Tagged Superoxide Dismutase and Its Analysis in Capillary Electrophoresis

Quantum dots (QDs) have a broad range of applications in cell biolabeling, cancer treatment, metastasis imaging, and therapeutic drug monitoring. Despite their wide use, relatively little is known about their influence on other molecules. Interactions between QDs and proteins can influence the properties of both nanoparticles and proteins. The effect of mercaptosuccinic acid-capped CdTe QDs on intercellular copper–zinc superoxide dismutase (SOD1)—one of the main enzymatic antioxidants—was investigated. Incubation of SOD1 with QDs caused an increase in SOD1 activity, unlike in the case of CdCl₂, which inhibited SOD1. Moreover, this effect on SOD1 increased with the size and potential of QDs, although the effect became clearly visible in higher concentrations of QDs. The intensity of QD-SOD1 fluorescence, analyzed with the use of capillary electrophoresis with laser-induced fluorescence detection, was dependent on SOD1 concentration. In the case of green QDs, the fluorescence signal decreased with increasing SOD1 concentration. In contrast, the signal strength for Y-QD complexes was not dependent on SOD1 dilutions. The migration time of QDs and their complexes with SOD1 varied depending on the type of QD used. The migration time of G-QD complexes with SOD1 differed slightly. However, in the case of Y-QD complexes with SOD1, the differences in the migration time were not dependent on SOD concentration. This research shows that QDs interact with SOD1 and the influence of QDs on SOD activity is size-dependent. With this knowledge, one might be able to control the activation/inhibition of specific enzymes, such as SOD1.     

Effect of nanodiamond additives on the structure and gas‐transport properties of a poly(phenylene–isophtalamide) matrix

Nanodiamonds (NDs) are specific carbon nanoparticles approximately 5 nm in diameter with a large and accessible surface containing functional groups. Poly(phenylene–isophtalamide) (PA)–ND composites were prepared by solid‐phase dispersal and used for dense film formation. The PA–ND composites were analyzed by Fourier transform infrared spectroscopy. The membrane structure was determined on the basis of density measurement and morphological study by atomic force microscopy. The gas‐transport properties were measured over a wide range of temperatures from 30 to 100 °C for the following series of penetrants: H₂, N₂, O₂, and CO₂. The experimental data of gas permeability were compared with the permeability values calculated from Maxwell's model. Data on the permeability and diffusion coefficients were used to calculate the activation energies. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46320.