Screening for biohydrogen production by cyanobacteria isolated from the Baltic Sea and Finnish lakes

Cyanobacteria are the only bacteria capable of performing oxygenic photosynthesis in which they harness solar energy and convert it into chemical energy stored in carbohydrates. Under specific conditions, cyanobacteria can use solar energy to produce also molecular hydrogen.     

Antistress Action of Melanocortin Derivatives Associated with Correction of Gene Expression Patterns in the Hippocampus of Male Rats Following Acute Stress

Natural melanocortins (MCs) have been used in the successful development of drugs with neuroprotective properties. Here, we studied the behavioral effects and molecular genetic mechanisms of two synthetic MC derivatives-ACTH(4–7)PGP (Semax) and ACTH(6–9)PGP under normal and acute restraint stress (ARS) conditions. Administration of Semax or ACTH(6–9)PGP (100 μg/kg) to rats 30 min before ARS attenuated ARS-induced behavioral alterations. Using high-throughput RNA sequencing (RNA-Seq), we identified 1359 differentially expressed genes (DEGs) in the hippocampus of vehicle-treated rats subjected to ARS, using a cutoff of >1.5 fold change and adjusted p-value (Padj) < 0.05, in samples collected 4.5 h after the ARS. Semax administration produced > 1500 DEGs, whereas ACTH(6–9)PGP administration led to <400 DEGs at 4.5 h after ARS. Nevertheless, ~250 overlapping DEGs were identified, and expression of these DEGs was changed unidirectionally by both peptides under ARS conditions. Modulation of the expression of genes associated with biogenesis, translation of RNA, DNA replication, and immune and nervous system function was produced by both peptides. Furthermore, both peptides upregulated the expression levels of many genes that displayed decreased expression after ARS, and vice versa, the MC peptides downregulated the expression levels of genes that were upregulated by ARS. Consequently, the antistress action of MC peptides may be associated with a correction of gene expression patterns that are disrupted during ARS.     

Efficient All-Perovskite White Light-Emitting Diodes Made of In Situ Grown Perovskite-Mesoporous Silica Nanocomposites

Metal halide perovskite quantum dots (QDs) have emerged as potential materials for high brightness, wide color gamut, and cost-effective backlight emission due to their high photoluminescence quantum yields, narrow emission linewidths, and tunable bandgaps. Herein, CsPbX₃/SBA-15 nanocomposites are prepared with outstanding optical properties and high stability through an in situ growth strategy using mesoporous silica particles. According to finite-difference time-domain simulations, the mesoporous structure provides a strong waveguide effect on perovskite QDs and the uniform dispersion suppresses reabsorption losses, improving the overall photoconversion efficiency of perovskite QDs. The as-fabricated perovskite monochromatic light-emitting diode (LED) has a maximum luminous efficiency of 183 lm W⁻¹, which is the highest for monochromatic perovskite LEDs reported to date. A further benefit of this work is that the white devices, which combine the green and red perovskite nanocomposites with commercial blue LED, exhibit a high luminous efficiency of 116 lm W⁻¹ and a wide color gamut (125% for NTSC and 94% for Rec. 2020) with coordinates of (0.33,0.31).     

ZnO ultra-fine powders and films: hydrothermal synthesis,luminescence and UV lasing at room temperature

Zinc oxide ultra-fine crystalline powders and polycrystalline films of high optical quality were synthesized under soft hydrothermal conditions. The phase composition, crystal morphology, and luminescent properties of submicron ZnO powders and films were studied depending on synthesis conditions (system composition, precursor kind, solvent type and concentration, temperature). For the systems containing metallic zinc, the ZnO growth mechanism was suggested. The most intensive UV luminescence and the highest values of I_UV/I_VIS were observed for polycrystalline films grown on Zn substrates. Low-threshold UV lasing at room temperature was found for ZnO-films, grown in hydrothermal systems with hydroxide or halide solutions as solvents, E _th = 1–5 MW/cm². The lowest threshold was observed on the ZnO films grown using LiOH as a solvent and zinc nitrate as ZnO-precursor. Clear mode structures with line-width 0.3 nm are characteristic of the lasing spectra.     

The resonant tunneling of holes through double-barrier structures with InAs QDs at the center of a GaAs quantum well

The effect of InAs quantum dots (QDs) grown in the center of a GaAs quantum well on the tunneling characteristics of resonant-tunneling diodes based on p-AlAs/GaAs/AlAs heterostructures is studied. The introduction of QDs results in a shift and broadening of resonance peaks in the current-voltage characteristics of the diodes; however, this effect is found to be strongly dependent on the number of the 2D subband involved in the tunneling. The obtained dependence is attributed to origination of the fluctuation potential in the vicinity of the QD layer.     

Confocal Annular Josephson Tunnel Junctions with Large Eccentricity

Confocal annular Josephson tunnel junctions (CAJTJs), which are the natural generalization of the circular annular Josephson tunnel junctions, have a rich nonlinear phenomenology due to the intrinsic non-uniformity of their planar tunnel barrier delimited by two closely spaced confocal ellipses. In the presence of a uniform magnetic field in the barrier plane, the periodically changing width of the elliptical annulus generates a asymmetric double-well for a Josephson vortex trapped in a long and narrow CAJTJ. The preparation and readout of the vortex pinned in one of the two potential minima, which are important for the possible realization of a vortex qubit, have been numerically and experimentally investigated for CAJTJs with the moderate aspect ratio 2:1. In this work, we focus on the impact of the annulus eccentricity on the properties of the vortex potential profile and study the depinning mechanism of a fluxon in more eccentric samples with aspect ratio 4:1. We also discuss the effects of the temperature-dependent losses as well as the influence of the current and magnetic noise.     

Effects of Solution History on Sol‐Gel Processed Tin‐Oxide Thin‐Film Transistors

Antimony‐doped tin‐oxide (SbTO) thin films deposited by solution processing methods represent a promising avenue toward low‐cost transparent and flexible electronics, but reproducibility and performance homogeneity of devices prepared from these thin films have been seldom investigated. In this study, the role of sol‐gel precursor aging is investigated by comparing SbTO thin‐film transistors (TFT) fabricated from two different sol‐gel solutions: the first one was aged for 4 years, whereas the second was prepared freshly. For each of the solutions, a set of TFT was assembled on the same chip, to investigate the distinct roles of aging and sample inhomogeneity on the electronic and transport properties of SbTO. Higher electron mobility, but lower on/off ratios, was found in TFTs assembled from freshly prepared solution, an effect that may be assigned to larger size of SbTO grains. This study demonstrates the critical role of the solution “history” in determining the properties and reproducibility of SbTO TFTs, over other factors, including local film inhomogeneity and local fluctuations of the annealing temperature.     

Adsorption of β-glucuronidase and estrogens on pectin/lignin hydrogel particles

The objective of this study was to generate supramolecular complexes of pectin and lignin with properties necessary to interrupt the enterohepatic circulation (EHC) of estrogens. Three types of pectin hydrogel particles were prepared from citrus pectin (PHP), citrus pectin/wheat lignin (PL_WHP), or citrus pectin/oak lignin (PL_OHP). The surface of PHP was smooth, whereas the surface of PL_WHP had irregularly arranged structures and PL_OHP contained pores. PHP actively adsorbed microbial β-glucuronidase and moderately adsorbed estrogens. PL_WHP had moderate and PL_OHP high affinity for estrogens. Thus, PL_OHP meets the requirements of a complex capable of interrupting the EHC of estrogens.     

Testing for ellipsoidal symmetry: A comparison study

The focus of this paper is the methodology for testing ellipsoidal symmetry, which was recently proposed by Koltchinskii and Sakhanenko [Koltchinskii, V., Sakhanenko, L. 2000. Testing for ellipsoidal symmetry of a multivariate distribution. In: Giné, E., Mason, D., Wellner, J. (Eds.), High Dimensional Probability II. In: Progress in Probability, Birkhäuser, Boston, pp. 493-510]. It is a class of omnibus bootstrap tests that are affine invariant and consistent against any fixed alternative. First, we study their behavior under a sequence of local alternatives. Secondly, a finite sample comparison study of this new class of tests with other popular methods given by Beran, Manzotti et al., and Huffer et al. is carried out. We find that the new tests outperform other methods in preserving the level and have superior power for the most of the chosen alternatives. We also suggest a tool for identifying periods of financial instability and crises when these tests are applied to the distribution of the return rates of stock market indices. These tests can be used in place of tests for normality of asset return distributions since ellipsoidally symmetric distributions are the natural extensions of multivariate normal distributions, so that the capital asset pricing model holds.     

Hydrogen transport in single-walled carbon nanotubes encapsulated by palladium

Hydrogen transport and loading into single-walled carbon nanotubes (SWCNT) encapsulated by thin Pd layers onto a massive Pd substrate were studied using a complex of vacuum thermal desorption, cyclic voltammetry and ESR methods. By adding SWCNT the hydrogen capacity of the Pd–SWCNT composite under electrochemical loading increases as much as 25% relative to Palladium metal alone. This provides moderate growth in the gravimetric capacity of the total composite based on a massive Pd substrate. The hydrogen binding energy in the SWCNT (eH = 0.075 eV/H-atom), estimated by studies of hydrogen transport in the Pd–SWCNT composite was lower than predicted for the Pd–SWCNT complex, but higher than the physisorption on the bare SWCNT. Using ESR we established that the Pd–C_x e-complexes formed at the wall of nanotube could be considered as hydrogen adsorption site, providing both high net gravimetric capacity and low hydrogen binding energy in the Pd encapsulated SWCNT. The results obtained provide an opportunity to probe a condensed hydrogen phase of nanometer scale confined in SWCNT, encapsulated by transition metals.