Membrane-Bound Ferric Hemoglobin in Nucleated Erythrocytes of the Black Scorpionfish Scorpaena porcus, Linnaeus 1758.

The content of membrane-bound methemoglobin (MtHb) in nucleated erythrocytes was studied in the black scorpionfish Scorpaena porcus (Linnaeus, 1758) in vitro. Spectral characteristics were determined for a whole hemolysate, a hemolysate obtained by stroma precipitation (a clarified hemolysate), and a resuspended stroma. The MtHb proportion in the erythrocyte stroma was found to exceed 80% (6.20 ± 0.59 µM). Clarified hemolysates were nearly free of MtHb (0.5 ± 0.2 µM). Membrane-bound ferric hemoglobin did not affect the erythrocyte resistance to osmotic shock. The osmotic fragility range was determined using a LaSca-TM laser microparticle analyzer (BioMedSystems, Russia) to be 102-136 mOsm/kg, much the same as in other bony fish species. A nitrite load (10 mg/L) significantly increased the MtHb content in the blood. However, the membrane-bound ferric hemoglobin content did not change significantly, amounting to 6.34 ± 1.09 µM (approximately 95%). The finding suggested a functional importance for MtHb present in the plasma membrane of nucleated erythrocytes. Membrane-bound MtHb was assumed to neutralize the external oxidative load and the toxic effect of hydrogen sulfide in bottom water layers, where the species lives.

Improving sensitivity of XANES structural fit to the bridged metal-metal coordination.

Hard X-ray absorption spectroscopy is a valuable in situ probe for non-destructive diagnostics of metal sites. The low-energy interval of a spectrum (XANES) contains information about the metal oxidation state, ligand type, symmetry and distances in the first coordination shell but shows almost no dependency on the bridged metal-metal bond length. The higher-energy interval (EXAFS), on the contrary, is more sensitive to the coordination numbers and can decouple the contribution from distances in different coordination shells. Supervised machine-learning methods can combine information from different intervals of a spectrum; however, computational approaches for the near-edge region of the spectrum and higher energies are different. This work aims to keep all benefits of XANES and extend its sensitivity towards the interatomic distances in the first and second coordination shells. Using a binuclear bridged copper complex as a case study and cross-validation analysis as a quantitative tool it is shown that the first 170 eV above the edge are already sufficient to balance the contributions of Cu-O/N scattering and Cu-Cu scattering. As a more general outcome this work highlights the trivial but often overlooked importance of using `longer' energy intervals of XANES for structural refinement and machine-learning predictions. The first 200 eV above the absorption edge still do not require parametrization of Debye-Waller damping and can be calculated within full multiple scattering or finite difference approximations with only moderately increased computational costs.

Monocyclicity in the Function of the Erythroid Hematopoietic Lineage in Teleost Fish Exemplified by Platichthys Flesus (Linnaeus, 1758).

The erythroid lineage was studied in the flounder-gloss (Platichthys flesus Linnaeus, 1758) during the annual cycle. The erythrocyte count in the blood was determined along with the contents of immature erythroid forms (basophilic and polychromatophilic normoblasts) in the head kidney (pronephros) and the blood. Cell proliferative activity was inferred from the [3H]thymidine inclusion in circulating immature erythrocytes. Irregularity was observed in erythropoiesis occurring in flounder-gloss hematopoietic tissue. Intense production of erythroid mass was mainly associated with a post-spawning period. This was evident from an increase in the contents of immature erythroid forms in the pronephros and circulating blood and an increase in their proliferative activity. The changes were associated with peculiarities of the erythroid system organization, which precludes regular production of erythropoietin in the kidney in teleost fish.

Effect of hypersalinic stress on hemocyte morphology and hemolymph cellular composition of the ark clam (Anadarakagoshimensis).

Bivalve mollusks as typical osmoconformers are unable to maintain a constant level of internal osmolarity in conditions of salinity stress. Adaptation to fluctuations of environmental salinity is achieved through cellular osmoregulatory responses, which are accompanied with a substantial shift in functional state of cells. In the present work we investigated the effect of hypersalinity stress on hemolymph cellular composition and morphology of the ark clam (Anadara kagoshimensis) hemocytes. Ark clams were subjected to a gradual increase of environmental salinity from 18‰ to 35‰ and 45‰ and maintained at those conditions for two days. Exposure to hypersalinity 35‰ induced changes in erythrocyte morphology and led to a decrease of their diameter. At salinity 45‰ a substantial increase of hemocyte average diameter was observed, whereas the shape of cells did not change (18‰). Hyperosmotic stress was not associated with changes in hemocyte viability as well as changes in hemolymph cellular composition. The results of the present work demonstrate high tolerance of A. kagoshimensis to short-time exposure to hypersalinic conditions.

Influences of Partial Destruction of Ti-MOFs on Photo(electro)catalytic H2 Evolution by Dominating Role of Charge Carrier Trapping over Surface Area.

The design of water-stable photo and electrocatalysts of metal-organic frameworks (MOFs) for its promising catalytic applications at long-term irradiations or persisted current loads is extremely necessary but still remains as challenging. A limited number of reports on Ti-MOF-based catalysts for water splitting are only available to explain and understand the correlation between the nature of materials and MOFs array. Herein, spherical Ti-MOFs and corresponding partially annealed hollow core-shell Ti-MOFs (Ti-MOF/D) are designed and the correlation with their photo(electro)catalytic water splitting performance is evaluated. The switchable valence state of Ti for the Ti-MOF as a function of molecular bonding is the possible reason behind the observed photocatalytic hydrogen generation and light-harvesting ability of the system. Besides, the defect state, solid core-shell mesoporous structure, and active sites of Ti-MOF help to trap the charge carriers and the reduction of the recombination process. This phenomenon is absent for hollow core-shells Ti-MOF/D spheres due to the rigid TiO2 outer surface although there is a contradiction in surface area with Ti-MOF. Considering the diversity of Ti-MOF and Ti-MOF/D, further novel research can be designed using this way to manipulate their properties as per the requirements.

Functional changes in hemocytes and antioxidant activity in gills of the ark clam Anadara kagoshimensis (Bivalvia: Arcidae) induced by salinity fluctuations.

This study describes the analysis of antioxidant enzymatic activities (catalase and superoxide dismutase) in gills and functional state of hemocytes (osmotic stability, mitochondrial membrane potential) of ark clams (Anadara kagoshimensis) from the Black Sea basin exposed to salinity stress. For this, the effects of 48 h periods of exposure to low (8 ‰, 14 ‰) and high (35 ‰, 45 ‰) salinity were assessed. Our results showed that ark clams, A. kagoshimensis, possessed pronounced tolerance to hypersalinity stress and are sensitive to a short-time hyposalinity treatment. Salinity 35 ‰ inhibited production of reactive oxygen species (ROS) by hemocytes and did not affect their levels of mitochondrial membrane potential. Acclimation to 45 ‰ salinity caused significant increase in mitochondrial membrane potential accompanied with recovery of intracellular ROS levels up to controls levels. Acclimation to low salinity (8 ‰) induced an increase in both ROS and mitochondrial membrane potential levels in hemocytes. Catalase and superoxide dismutase activity in gills decreased following acclimation to low (8 ‰) and high (35 ‰) salinity. Exposure to the highest salinity levels (45 ‰) led to a decrease of superoxide dismutase activity levels, but did not influence the levels of catalase activity. Acclimation to low and high salinity was not accompanied with changes in osmotic fragility of hemocytes despite osmotic fragility curve according to changes in hemolymph osmolarity. Based upon these results, we postulate the involvement of cellular osmoregulatory mechanisms in the adaptation of the ark clam to short-term fluctuations of environmental salinity.

Development of a ReaxFF potential for Au-Pd.

The bimetallic alloys often outperform their single-component counterparts due to synergistic effects. Being widely known, the Au-Pd alloy is a promising candidate for the novel heterogeneous nanocatalysts. Rational design of such systems requires theoretical simulations under ambient conditions.Ab initioquantum-mechanical calculations employ the density functional theory (DFT) and are limited to the systems with few tens of atoms and short timescales. The alternative solution implies development of reliable atomistic potentials. Among different approaches ReaxFF combines chemical accuracy and low computational costs. However, the development of a new potential is a problem without unique solution and thus requires accurate validation criteria. In this work we construct ReaxFF potential for the Au-Pd system based onab initioDFT calculations for bulk structures, slabs and nanoparticles with different stoichiometry. The validation was performed with molecular dynamics and Monte-Carlo calculations. We present several optimal parametrizations that describe experimental bulk mechanical and thermal properties, atomic order-disorder phase transition temperatures and the resulting ordered crystal structures.

Evolution of the active species of homogeneous Ru hydrodeoxygenation catalysts in ionic liquids.

This work establishes structure-property relationships in Ru-based catalytic systems for selective hydrodeoxygenation of ketones to alkenes by combining extensive catalytic testing, in situ X-ray absorption spectroscopy (XAS) under high pressures and temperatures and ex situ XAS structural characterization supported by density functional theory (DFT) calculations. Catalytic tests revealed the difference in hydrogenation selectivity for ketones (exemplified by acetone) or alkenes (exemplified by propene) upon changing the reaction conditions, more specifically in the presence of CO during a pretreatment step. XAS data demonstrated the evolution of the local ruthenium structure with different amounts of Cl/Br and CO ligands. In addition, in the absence of CO, the catalyst was reduced to Ru0, and this was associated with a significant decrease of the selectivity for ketone hydrogenation. For the Ru-bromide carbonyl complex, selectivity towards acetone hydrogenation over propene hydrogenation was explained on the basis of different relative energies of the first intermediate states of each reaction. These results give a complete understanding of the evolution of the Ru species, used for the catalytic valorization of biobased polyols to olefins in ionic liquids, identifying the undesired deactivation routes as well as possibilities for reactivation.

Revisiting the Extended X-ray Absorption Fine Structure Fitting Procedure through a Machine Learning-Based Approach.

A novel approach for the analysis of extended X-ray absorption fine structure (EXAFS) spectra is developed exploiting an inverse machine learning-based algorithm. Through this approach, it is possible to explore and account for, in a precise way, the nonlinear geometry dependence of the photoelectron backscattering phases and amplitudes of single and multiple scattering paths. In addition, the determined parameters are directly related to the 3D atomic structure, without the need to use complex parametrization as in the classical fitting approach. The applicability of the approach, its potential and the advantages over the classical fit were demonstrated by fitting the EXAFS data of two molecular systems, namely, the KAu (CN)2 and the [RuCl2(CO)3]2 complexes.

Machine learning powered by principal component descriptors as the key for sorted structural fit of XANES.

Modern synchrotron radiation sources and free electron laser made X-ray absorption spectroscopy (XAS) an analytical tool for the structural analysis of materials under in situ or operando conditions. Fourier approach applied to the extended region of the XAS spectrum (EXAFS) allows the estimation of the number of structural and non-structural parameters which can be refined through a fitting procedure. The near edge region of the XAS spectrum (XANES) is also sensitive to the coordinates of all the atoms in the local cluster around the absorbing atom. However, in contrast to EXAFS, the existing approaches of quantitative analysis provide no estimation for the number of structural parameters that can be evaluated for a given XANES spectrum. This problem exists both for the classical gradient descent approaches and for modern machine learning methods based on neural networks. We developed a new approach for rational fit based on principal component descriptors of the spectrum. In this work the principal component analysis (PCA) is applied to a dataset of theoretical spectra calculated a priori on a grid of variable structural parameters of a molecule or cluster. Each principal component of the dataset is related then to a combined variation of several structural parameters, similar to the vibrational normal mode. Orthogonal principal components determine orthogonal deformations that can be extracted independently upon the analysis of the XANES spectrum. Applying statistical criteria, the PCA-based fit of the XANES determines the accessible structural information in the spectrum for a given system.

Valence tautomeric transition of bis(o-dioxolene) cobalt complex in solid state and solution.

Valence tautomer transition occurs mainly in 3d metalorganic complexes with redox-active ligands and makes them potential candidates for single-molecular switches. The transition occurs under temperature, pressure, or light-induced stimuli and is strongly affected by the intermolecular interactions. However single-crystal x-ray diffraction is not always applicable to such systems when crystal structure is destroyed upon transition or system is studied in the solution. Such an example is bis(o-semiquinonato) cobalt complex with TEMPO-functionalized iminopyridine ancillary ligand. In this work we apply two complementary techniques-ligand-sensitive Fourier transform infrared spectroscopy (FTIR) and metal sensitive Co K-edge x-ray absorption spectroscopy (XAS). In a solid state, a temperature hysteresis of magnetization larger than 40 K was observed upon cyclic cooling-heating. So, the temperature of phase transition upon cooling is about 40 K lower than that upon heating. In solution, the x-ray absorption spectra for high-temperature and low-temperature states were similar to that in the solid form, but the hysteresis was absent. Two methods are can probe valence tautomer transition, but XAS has an advantage for the liquid phase analysis and FTIR has larger sensitivity to the ligand related interactions in solid.

Superfluid ß phase of

It is known that in low magnetic fields the superfluid transition of ^{3}He in nematic aerogel occurs into the polar phase. Using a vibrating aerogel resonator, we observe that in high magnetic fields this transition splits into two discrete transitions, occurring at different temperatures. According to theoretical models, a new superfluid phase-the ß phase-should be realized between these two transitions. The temperature range of existence of the new phase is measured as a function of magnetic field. The results are well consistent with theoretical expectations for the ß phase.

Fundamental dissipation due to bound fermions in the zero-temperature limit.

The ground state of a fermionic condensate is well protected against perturbations in the presence of an isotropic gap. Regions of gap suppression, surfaces and vortex cores which host Andreev-bound states, seemingly lift that strict protection. Here we show that in superfluid 3He the role of bound states is more subtle: when a macroscopic object moves in the superfluid at velocities exceeding the Landau critical velocity, little to no bulk pair breaking takes place, while the damping observed originates from the bound states covering the moving object. We identify two separate timescales that govern the bound state dynamics, one of them much longer than theoretically anticipated, and show that the bound states do not interact with bulk excitations.

A mini-review of X-ray photodynamic therapy (XPDT) nonoagent constituents' safety and relevant design considerations.

Conventional photodynamic therapy (PDT) has proved effective in the management of primary tumors and individual metastases. However, most cancer mortality arises from wide-spread multiple metastases. The latter has thus become the principal target in oncology, and X-ray induced photodynamic therapy (XPDT or PDTX) offers a great solution for adapting the PDT principle to deep tumors and scattered metastases. Developing agents capable of being excited by X-rays and emitting visible light to excite photosensitizers is based on challenging physical and chemical technologies, but there are fundamental biological limitations that are to be accounted for as well. In the present review, we have established eight major groups of safety determinants of NPs encompassing 22 parameters of clinical applicability of XPDT nanoparticulate formulations. Most, if not all, of these parameters can be accounted for and optimized during the design and development of novel XPDT nanoparticles.

The enhanced photocatalytic performance of SnS2@MoS2 QDs with highly-efficient charge transfer and visible light utilization for selective reduction of mythlen-blue.

Molybdenum disulfide (MoS2) has recently been considered as an effective material for potential photocatalytic applications; however, its photocatalytic activity was limited due to the low density of active sites. In this work, MoS2 Quantum dots (QDs) were synthesized via the ultrasonication technique to construct heterostructure with SnS2 nanosheets (SnS2@MoS2 QDs) and the prepared materials were tested for photocatalytic applications for Methylene blue (MB). Pristine SnS2 and SnS2@MoS2 QDs nanocomposite were analyzed by XRD, TEM, PL, and Uv-Vis. Both SnS2 and SnS2@MoS2 QDs exhibited a single trigonal phase with the P-3m1 space group. The TEM analysis confirmed the coupling between the pristine SnS2 and SnS2@MoS2 QDs. The results of photocatalytic activity toward MB indicated that SnS2@MoS2 QDs material exhibits much superior photocatalytic performance compared to pristine SnS2. The excellent photodegradation performance of SnS2@MoS2 QDs is due in the main to the formation of heterojunction between SnS2 and MoS2 QDs with narrow bandgap formation, which results in a facile carriers transfer and thus high photocatalytic efficiency. A representative mechanism of the photodegradation for SnS2@MoS2 QDs photocatalyst was proposed. Such an ultrasonic technique is capable of producing small metallic particle size that can be used to construct new heterostructures for water remediation applications.

Erythrocyte profile of circulating blood of Neogobius melanostomus (Pallas, 1814) under conditions of experimental hypothermia.

The influence of hypothermia on erythrocyte profile of thermophile teleost species round goby, Neogobius melanostomus (Pallas, 1814), has been studied. Fish were acclimated to temperature 1-2оС, 15-16оС and 19-20оС (control group) and held at given conditions for 5 days. The number of red blood cell precursors (pronormoblasts, basophilic and polychromatophilic normoblasts) in circulating blood has been estimated. Also, the number of abnormal erythrocytes, i.e. cells with micronuclei, nuclei invaginations, red blood cell shades, dacryocytes and cells undergoing amitosis has been determined on smears. The number of immature erythrocytes increased more than two times (p < 0,001) at 1-2оС. The number of low-differentiated precursors, pronormoblasts and early basophilic normoblasts, increased for the most part. The number of abnormal erythrocytes did not change substantially, The changes in cellular blood composition were accompanied with the increase of plasma lactate concentration, indicating hypoxic state of fish. The results of the present work indicate that hematopoietic tissue remains sensitive to controlling factors at hypothermia, such as hypoxia, and may enhance proliferation and differentiation of erythroid cells.

Morphologic, cytometric and functional characterisation of Anadara kagoshimensis hemocytes.

Circulating hemocytes of ark clam, Anadara kagoshimensis, were investigated using light microscopy and flow cytometry. Hemolymph contained 3 morphotype of cells, amebocytes, erythrocytes and intermediate type cells, which formed two distinct subpopulations on flow cytometric dot plots. Large cells (intermediate morphotype and erythrocytes) amounted 85.6 ± 2.8% total cells in hemolymph. Erythrocytes were hemoglobin-containing cells with up to 40 granules presented in the cytoplasm. All hemocyte types, observed in the ark clam hemolymph demonstrated equal capacity to spontaneous production of reactive oxygen species.

Hemoglobin deoxygenation and methemoglobinemia prevent regulatory volume decrease in crucian carp (Carassius carassius) red blood cells.

Fish red blood cells (RBCs) exhibit an oxygen-dependent regulatory volume decrease (RVD) in hypoosmotic environment. In higher vertebrates, membrane-associated hemoglobin is involved in the regulation of osmotic ion movements across the cellular membrane. However, whether the hemoglobin conformational state plays a role in the regulation of osmotic responses in fish red blood cells is still not fully understood. We found that changes in hemoglobin conformation influence the pattern of the regulatory volume decrease in Carassius carassius red blood cells. In oxygenated cells (96.4 ± 3.7% oxygenated hemoglobin), the volume recovery was completed within 125 min. Deoxygenation of hemoglobin (96.5 ± 2.7% of deoxygenated hemoglobin) inhibited the volume decrease in hyposmotically swollen red blood cells. Reoxygenation restored regulatory volume decrease in cells within 5 min. Induced methemoglobinemia (48.4 ± 1.8% of methemoglobin and 41.3 ± 2.3% of deoxygenated hemoglobin) blocked the process of volume recovery and significantly decreased osmotic stability of red blood cells.

The role of defects in the physical properties of mechanically activated PbTiO3 ferroelectrics.

In this work a multi-technique characterization was performed for the first time to trace the influence of structural defects on the physical properties of PbTiO3 ferroelectrics. The structural defects were generated by the mechanical activation in the pressure range of 40-320 MPa, by combining a uniaxial strain with a shear deformation in the Bridgman anvils. The induced defectivity of PbTiO3 was assessed via calculation of unit cell parameters, estimation of the regions of coherent scattering and analysis of micro-deformations. The Debye characteristic temperature, the static mean-square displacement, the Debye-Waller isotropic factor, the vibrational spectra and dielectric properties of the activated PbTiO3 ceramics are presented. The high-quality PbTiO3 ceramics was prepared without modifiers, hence, changing the concentration of structural defects via mechanical activation constitutes a chemically clean method for fine tuning of the dielectric properties of PbTiO3.

Gene Encoding a Novel Enzyme of LDH2/MDH2 Family is Lost in Plant and Animal Genomes During Transition to Land.

L-Lactate/malate dehydrogenases (LDH/MDH) and type 2 L-lactate/malate dehydrogenases (LDH2/MDH2) belong to NADH/NADPH-dependent oxidoreductases (anaerobic dehydrogenases). They form a large protein superfamily with multiple enzyme homologs found in all branches of life: from bacteria and archaea to eukaryotes, and play an essential role in metabolism. Here, we describe the gene encoding a new enzyme of LDH2/MDH2 oxidoreductase family. This gene is found in genomes of all studied groups/classes of bacteria and fungi. In the plant kingdom, this gene was observed only in algae, but not in bryophyta or spermatophyta. This gene is present in all taxonomic groups of animal kingdom beginning with protozoa, but is lost in lungfishes and other, higher taxa of vertebrates (amphibians, reptiles, avians and mammals). Since the gene encoding the new enzyme is found only in taxa associated with the aquatic environment, we named it AqE (aquatic enzyme). We demonstrated that AqE gene is convergently lost in different independent lineages of animals and plants. Interestingly, the loss of the gene is consistently associated with transition from aquatic to terrestrial life forms, which suggests that this enzyme is essential in aquatic environment, but redundant or even detrimental in terrestrial organisms.