Activity Of Ca2 Research Articles

Purification of Si–Ti alloys via vacuum evaporation: A thermodynamic and kinetic study of Ca impurity removal

Vacuum refining is a green technology for separating Ca from Si–Ti alloys. This study investigated the kinetics of Ca evaporation from Si–Ti melts in vacuum refining, including the effect of holding time and melt temperature and composition. Although the Ca activity in Si–Ti melts is an essential thermodynamic property that affects the Ca evaporation kinetics, it has not been measured to date. Consequently, another objective of this study was to determine the Ca activity using a chemical equilibration technique and investigate its effect on Ca evaporation. The results show that the activity of Ca in the Si–Ti melt decreased gradually with increasing Ti content in the melt, which reduced the Ca removal ratio. The removal ratio of Ca increased with the temperature and holding time. The apparent evaporation rate of Ca was consistent with the first-order law, and the apparent evaporation rate constants of Ca in 15%Si–Ti melt at 1673 and 1773 K were 2.1 × 10−6 and 2.8 × 10−6 m/s, respectively. The apparent activation energy for Ca evaporation from Si–15 wt%Ti melt was determined to be 68.2 kJ/mol, and the rate-determining step to be Ca mass transfer at the melt boundary layer.

Mitochondrial carbonic anhydrase VA and VB: properties and roles in health and disease.

Carbonic anhydrase V (CAV), a mitochondrial enzyme, was first isolated from guinea-pig liver and subsequently identified in mice and humans. Later, studies revealed that the mouse genome contains two mitochondrial CA sequences, named Car5A and Car5B. The CAVA enzyme is most highly expressed in the liver, whereas CAVB shows a broad tissue distribution. Car5A knockout mice demonstrated a predominant role for CAVA in ammonia detoxification, whereas the roles of CAVB in ureagenesis and gluconeogenesis were evident only in the absence of CAVA. Previous studies have suggested that CAVA is mainly involved in the provision of HCO3 - for biosynthetic processes. In children, mutations in the CA5A gene led to reduced CA activity, and the enzyme was sensitive to increased temperature. The metabolic profiles of these children showed a reduced supply of HCO3 - to the enzymes that take part in intermediary metabolism: carbamoylphosphate synthetase, pyruvate carboxylase, propionyl-CoA carboxylase and 3-methylcrotonyl-CoA carboxylase. Although the role of CAVB is still poorly understood, a recent study reported that it plays an essential role in human Sertoli cells, which sustain spermatogenesis. Metabolic disease associated with CAVA appears to be more common than other inborn errors of metabolism and responds well to treatment with N-carbamyl-l-glutamate. Therefore, early identification of hyperammonaemia will allow specific treatment with N-carbamyl-l-glutamate and prevent neurological sequelae. Carbonic anhydrase VA deficiency should therefore be considered a treatable condition in the differential diagnosis of hyperammonaemia in neonates and young children.

Phosphorylation states greatly regulate the activity and gating properties of Cav 3.1 T-type Ca2+ channels.

Cav 3.1 T-type Ca2+ channels play pivotal roles in neuronal low-threshold spikes, visceral pain, and pacemaker activity. Phosphorylation has been reported to potently regulate the activity and gating properties of Cav 3.1 channels. However, systematic identification of phosphorylation sites (phosphosites) in Cav 3.1 channel has been poorly investigated. In this work, we analyzed rat Cav 3.1 protein expressed in HEK-293 cells by mass spectrometry, identified 30 phosphosites located at the cytoplasmic regions, and illustrated them as a Cav 3.1 phosphorylation map which includes the reported mouse Cav 3.1 phosphosites. Site-directed mutagenesis of the phosphosites to Ala residues and functional analysis of the phospho-silent Cav 3.1 mutants expressed in Xenopus oocytes showed that the phospho-silent mutation of the N-terminal Ser18 reduced its current amplitude with accelerated current kinetics and negatively shifted channel availability. Remarkably, the phospho-silent mutations of the C-terminal Ser residues (Ser1924, Ser2001, Ser2163, Ser2166, or Ser2189) greatly reduced their current amplitude without altering the voltage-dependent gating properties. In contrast, the phosphomimetic Asp mutations of Cav 3.1 on the N- and C-terminal Ser residues reversed the effects of the phospho-silent mutations. Collectively, these findings demonstrate that the multiple phosphosites of Cav 3.1 at the N- and C-terminal regions play crucial roles in the regulation of the channel activity and voltage-dependent gating properties.

Recycling and reuse performance of cobalt catalyst for coal hydrogasification

Hydrogasification (C + H2 → CH4) is a crucial reaction for obtaining CH4 from coal or biomass. However, the reaction is sluggish in the absence of a suitable catalyst. Cobalt is more catalytically active than iron, nickel, and alkali metals, but is expensive. To improve the process economy, catalyst recycling was investigated with a focus on cobalt and calcium (Co–Ca) catalyzed coal hydrogasification. The results revealed that Co existed as metallic state in the gasified residue, and it was strongly associated with Ca compounds. Co–Ca as nitrate and acetate exhibited significantly higher activity than that of chloride and sulfate. Nitrate acid (HNO3) can effectively leach Co and Ca from the residue, as the leaching efficiencies of Co and Ca exceeded 99.7 % and 98.0 %, respectively. Additionally, seventeen mineral impurity elements were extracted from the residue. With repeated recycling, the majority of impurities accumulated in the recovered catalyst and exhibited distinct effects on its activity. Al impurity demonstrated its ability to significantly lower the Co–Ca activity, whereas Fe, K, Na, Mg, P, and S could not. Because impurities inhibited Co reducibility, the catalytic performance of recovered Co–Ca decreased with each recycling. Inspired by the results, the proposed HNO3 leaching procedure was optimized using two-step precipitations for impurities removal, and a high activity of recovered catalyst was achieved. This study provides some insights into the recovery, deactivation, and regeneration of cobalt catalyst employed for coal or biomass hydrogasification.

Carbonic Anhydrase Inhibitors from Marine Natural Products.

Carbonic anhydrases (CAs, EC 4.2.1.1) are widespread metalloenzymes in organisms in all life kingdoms, being involved in pH regulation, metabolic processes and many other physiological and pathological conditions. CA inhibitors and activators thus possess applications as pharmacological agents in the management of a range of diseases. Marine natural products have allowed the identification of some highly interesting CA inhibitors, among which are sulfonamides, phenols, polyamines, coumarins and several other miscellaneous inhibitors, which are reviewed here. Psammaplin C and some bromophenols were the most investigated classes of such marine-based inhibitors and have been used as lead molecules for developing interesting types of potent and, in some cases, isoform-selective inhibitors, with applications as antitumor agents by inhibiting human CA XII and P-glycoprotein activities. Some phenols have shown interesting bacterial and fungal β-CA inhibitory effects. Marine natural products thus constitute a gold mine for identifying novel CA inhibitors, some of which may lead to the development of novel types of pharmacological agents.

Synthesis, Characterization, and Antibacterial Activity of Calcium Hydroxide Nanoparticles Against Gram‐Positive and Gram‐Negative Bacteria

AbstractCalcium hydroxide nanoparticles (Ca(OH)2 NPs) are of great interest in the development of new products due to their antibacterial properties. Chemical precipitation process was used for synthesizing Ca(OH)2 NPs. The synthesized Ca(OH)2 NPs were characterized by using X‐ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transmission Infrared Spectroscopy (FTIR), UV‐Visible spectroscopy, DLS (Dynamic Light Scattering) techniques. Ca(OH)2 NPs were assessed for antibacterial activity against gram‐positive bacteria (Bacillus subtilis, Staphylococcus aureus) and gram‐negative bacteria (Escherichia coli, Pseudomonas aeruginosa). The results showed reasonable bactericidal activity and flash out that the antibacterial activity of Ca(OH)2 had an important inhibitory activity against B. subtilis and P. aeruginosa which are gram‐positive and gram‐negative bacteria respectively. Reactive oxygen species (ROS) generation of Ca(OH)2 NPs were also studied and shows significant results against both gram negative and gram positive bacteria. From the analysis of the results, it was observed that Ca(OH)2 shows the best antibacterial activity against gram‐positive bacteria B. subtilis. Further, the possible mechanisms of antibacterial behaviour of Ca(OH)2 against each bacteria were suggested. These outcomes indicate that Ca(OH)2 could be utilized as a functional antibacterial material.

Electrochemical characteristics of Ca3Co4O9+δ oxygen electrode for reversible solid oxide cells

• Ca 3 Co 4 O 9+δ oxygen electrode shows superior durability under long-term operation. • Polarization promotes the electrochemical activity of Ca 3 Co 4 O 9+δ electrode. • Polarization improves the electrode/electrolyte interface. • The cell performance could be enhanced by 4 times by cathodic polarization. Reversible solid oxide cells (RSOCs) are clean electrochemical conversion devices that can flexibly operate between solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) patterns. Ca 3 Co 4 O 9+δ (CCO) material with a misfit-layered structure was successfully prepared and fully discussed as a oxygen electrode for RSOCs. The CCO electrode showed superior durability and excellent electrocatalytic activity for oxygen reactions. Both the ohmic and polarization resistances were decreased after alternating anodic and cathodic polarization for more than 100 h, demonstrated the activation of CCO electrode and an improvement of electrode/electrolyte interface. The peak power density of the single cell with CCO oxygen electrode was 614 mW·cm −2 after polarization at 500 mA·cm −2 for 4 h at 750 °C, which improved by 4 times than the unpolarized cell. The maximum electrolysis current density of 749 mA·cm −2 was obtained at 800 °C and 50 % water vapor, which corresponded to the hydrogen production rate of 311 mL·cm −2 ·h −1 . Results showed that CCO with good reversible polarization performance and long-term stability was a prospective oxygen electrode for RSOCs.

Interaction mechanism of a novel reagent scheme in the selective separation of scheelite from calcite

Up to now, the selective separation of scheelite and calcite is still tricky. Etidronic acid (abbreviated as EA or H4L) is an environmental scale inhibitor capable of chelating metal ions. This research adopted the EA as a selective depressant to separate scheelite from calcite. Flotation results of the single mineral, binary mixed minerals, and real ore showed that EA had better selectivity for calcite at pH 10.0 with sodium oleate (NaOL) as a collector. Zeta potential results found that EA adsorption amount on the positively charged calcite surfaces was more significant than that on the negatively charged scheelite surfaces. X-ray photoelectron spectroscopy, solution chemistry, and density functional theory (DFT) calculation further proved that on calcite, the active O atoms in the dominant species (HL3-) of EA had a strong chemical interaction with Ca sites to form a hydrophilic Ca–EA complex by O 2 s and Ca 3p orbitals hybrid. In contrast, the interaction with these on scheelite was significantly weaker. Afterward, NaOL tended to occupy the scheelite surfaces due to its higher activity of Ca rather than the calcite surfaces. Therefore, the difference in HL3- and OL- adsorption on both minerals achieved the selective separation of scheelite and calcite.

Calcium Channel Blockers as Hepatoprotective agents in Paracetamol and Alcohol-induced Hepatotoxicity Models (Preventive Method) in Rats

>Objective: To study the hepatoprotective activity of 3 Ca++ channel blockers namely felodipine (FEL), lercanidipine (LER), and isradipine (ISR) with three selected doses i.e; 1/4th TD, 1/2nd TD, and TD in paracetamol (PCM) and alcohol (ALC)-induced hepatotoxicity in rats both at preventing and curative aspects. Further, it was also reported that PCM and ALC producing hepatotoxicity by facilitating accumulation of excess Ca++ in hepatocyte. Ca++ channel blockers block the entry of Ca++ into the cells. Hence the present study is planned to evaluate the hepatoprotective activity of Ca++ channel blockers in the above-mentioned models. Materials and Methods: In rats, the hepatoprotective activity of Ca++ channel blockers is evaluated in PCM (2 g/Kg) and ALC (3.76 g/Kg) induced hepatotoxic models. Thiopental-induced sleeping time (TST), physical parameters like liver weight and liver volume, and biochemical parameters like alanine aminotransferase (ALT), aspartate aminotransferase (AST), serum alkaline phosphatase (ALP), serum direct bilirubin (BILD), serum total bilirubin (BILT), serum albumin (ALB), and serum total proteins (PRO), were estimated by Erba chem. Standard reference SIL produced significant hepatoprotective activity. Results: All three drugs significantly reduced liver weight to 6.07, 4.87, 5.51, 4.28, 6.10, and 5.02 g, respectively. Three drugs produced a significant reduction in liver volume noted as 6.03, 4.83, 5.45, 4.23, 6.05, and 4.96 mL, respectively, in paracetamol-induced hepatotoxicity. All three drugs significantly reduced liver weight, as 6.42, 5.65, 6.66, 6.34, 5.30, and 5.85 g, respectively. A significant reduction in liver volume was noted at 6.35, 5.53, 6.23, 5.18, and 5.80 mL, respectively, in alcohol-induced hepatotoxicity. Conclusion: Ca++ channel blockers too at three different doses at preventive and curative aspects produced a significant hepatoprotective activity in PCM and ALC-induced hepatotoxic models..

Fluid‐Mediated Mass Transfer Between Mafic and Ultramafic Rocks in Subduction Zones

AbstractMetasomatic reaction zones between mafic and ultramafic rocks exhumed from subduction zones provide a window into mass‐transfer processes at high pressure. However, accurate interpretation of the rock record requires distinguishing high‐pressure metasomatic processes from inherited oceanic signatures prior to subduction. We integrated constraints from bulk‐rock geochemical compositions and petrophysical properties, mineral chemistry, and thermodynamic modeling to understand the formation of reaction zones between juxtaposed metagabbro and serpentinite as exemplified by the Voltri Massif (Ligurian Alps, Italy). Distinct zones of variably metasomatized metagabbro are dominated by chlorite, amphibole, clinopyroxene, epidote, rutile, ilmenite, and titanite between serpentinite and eclogitic metagabbro. Whereas the precursor serpentinite and oxide gabbro formed and were likely already in contact in an oceanic setting, the reaction zones formed by diffusional Mg‐metasomatism between the two rocks from prograde to peak, to retrograde conditions in a subduction zone. Metasomatism of mafic rocks by Mg‐rich fluids that previously equilibrated with serpentinite could be widespread along the subduction interface, within the subducted slab, and the mantle wedge. Furthermore, the models predict that talc formation by Si‐metasomatism of serpentinite in subduction zones is limited by pressure‐dependent increase in the silica activity buffered by the serpentine‐talc equilibrium. Elevated activities of aqueous Ca and Al species would also favor the formation of chlorite and garnet. Accordingly, unusual conditions or processes would be required to stabilize abundant talc at high P‐T conditions. Alternatively, a different set of mineral assemblages, such as serpentine‐ or chlorite‐rich rocks, may be controlling the coupling‐decoupling transition of the plate interface.

Impact of NPK fertilization on hazelnut yield and soil chemical-microbiological properties of Hazelnut Orchards in Western Georgia

In this study, the effects of ground and foliar applications of the NPK fertilizers in hazelnut orchards on the soil chemical and microbiological properties and hazelnut yield were investigated. The fertilization practicesses from ground were done two times using NPK (20:10:10 +trace elements) on March and May while the fertilization practices from leaf were done three times using NK (15:12 +trace elements) on May, June and July at six different hazelnut orchards located on Samegrelo, Guria and Adjara regions in Western Georgia in 2018. The alkaline characterized fertilizer applications from soil generally increased soil reaction (pH), nutrient contents and EC values in different magnitude depends on the soil characteristics of locations. The lowest soil pH (4,40) and EC (0,107 dS m-1) values showed the highest increment (10,7% and 77,6%, respectively) over the control. The basal soil respiration and Cmic values of all hazelnut orchards were generally increased by the NPK ferilization. Increasing soil pH and EC by the fertilization also increased CA and DHA activity. The mean values of percent increase in yield and yield parameters by the NPK fertilization were obtained as 8,3% in yield, 13,3% in shelled nut weight, 10,0% in kernel weight and 5,1% in percent kernel efficiency. The hazelnut yield value had significant positive correlation with soil pH (0,669*), EC (0,652*) and Cmic (0,620*) values. The foliar fertilization and improving the soil properties of hazelnut orchards by the application of alkaline characteristic NPK fertilizer from soil increased hazelnut yield and yield parameters compare with the farmer applications or control treatments. The increments in soil microbiological properties and nutrients are considered as a desirable result in terms of sustainable soil management and plant nutrition for hazelnut orchards.

Impact of N-acetylcysteine (NAC) and calcium hydroxide intracanal medications in primary endodontic infection: a randomized clinical trial.

This RCT investigated the impact of N-acetylcysteine (NAC) and calcium hydroxide [Ca(OH)2] intracanal medications (ICMs) in primary endodontic infection with apical periodontitis (PEIAP). Thirty-six teeth with PEIAP were randomly divided into groups according to the ICM: NAC, Ca(OH)2 + saline solution (SSL), and Ca(OH)2 + 2% chlorhexidine-gel (2% CHX-gel) (all, n = 12). Root canal samples (RCSs) were collected before (s1) and after instrumentation (s2) and after 14days of ICM (s3). Chemomechanical preparation (CMP) was performed with a Reciproc file and 2.5% NaOCl. Checkerboard DNA-DNA hybridization was used to assess 40 target bacteria species. At s1, bacterial DNA was detected in 100% of RCSs (36/36). All 40 bacterial species were found in PEIAP. The mean number of species per RCS was 17.92 ± 13.18. The most frequent bacteria were S. mitis (65%), E. nodatum (63%), E. faecalis (63%), F. nucl sp vicentii (58%), T. forsythia (58%), and F. periodonticum (56%). CMP reduced the mean number of species per RCS to 6.8 ± 2.36 (p < 0.05). At s3, the intragroup analysis revealed a broader antimicrobial activity for Ca (OH)2 + 2% CHX-gel and NAC than Ca(OH)2 + SSL (p < 0.05). NAC eliminated 8/12 bacteria species resistant to both Ca (OH)2 ICMs, including P. micra, P. nigrescens, T. denticola, A. israelii, P. endodontalis, P. acnes, C. ochracea, and E. corrodens. Ca (OH)2 + 2% chlorhexidine gel (2% CHX gel) showed a greater bacterial elimination over the number of bacterial species; however, NAC eliminated 8/12 bacteria species resistant to both Ca (OH)2 ICMs (RBR-3xbnnn). The use of intracanal medication with a broad antimicrobial activity can optimize root canal disinfection. Ca(OH)2 + 2% CHX gel and NAC showed a broader antimicrobial activity than Ca(OH)2 + SSL against endodontic pathogens in primary root canal infection. Brazilian Registry of Clinical Trials (REBEC), No. RBR-3xbnnn.

A comparative study of carbonic anhydrase activity in lymphocytes from colorectal cancer tissues and adjacent healthy counterparts

Several carbonic anhydrase (CA, EC 4.2.1.1) isoforms play an essential role in processes connected to tumorigenesis, as they efficiently accelerate the hydration of carbon dioxide to bicarbonate and proton. In this context, examples are CA IX and CA XII, which were proved to be upregulated in many solid malignancies. On the other hand, cancer and the immune system are inextricably linked, and targeting the immune checkpoints recently was shown to efficiently improve the treatment of malignancies. In this study, we have investigated the expression of CA isoforms in tumour-infiltrating lymphocytes (TILs) that, according to the immunosurveillance theory, were suggested to have a crucial role in the development of colorectal cancer (CRC). T lymphocytes isolated from healthy surrounding mucosa showed a higher CA activity compared to those present in tumour and peripheral blood in the same patients. CA I and II were confirmed as enzyme isoforms involved in the process, as determined by proteomic analysis of corresponding TIL samples. These preliminary findings suggest a dysregulation of the local immune response in the CRC tissues and a loss of effective anticancer mechanisms mediated by CAs therein.

Variation in mineral composition by hydration and carbonation in calcium hydroxide matrix containing zeolite

Natural zeolite can modify the mechanical properties of concrete as a supplementary cementitious material based on pozzolanic activity. However, the pozzolanic reaction is difficult to explain because of the formation of amorphous reaction products and the complexity of concrete systems. In this study, the mineral, amorphpus phase compositions and pozzolanic reaction mechanism of zeolite were further investigated by performing X-ray diffraction (XRD) and magic angle spinning nuclear magnetic resonance (MAS NMR) analysis. Additionally, the pozzolanic activity of Ca(OH)2 (CH)/zeolite (CHZ, 0–50 wt% proportions of zeolite) specimens was investigated after 1, 3, 7, and 28 d of hydration. The pozzolanic products were identified as C-(A)-S-H gel and monocarboaluminate (AFmc) mineral. Zeolite, having a 5 wt% proportion of CHZ specimens, completely reacted after 3 d of hydration. The optimal zeolite proportion for forming AFmc minerals in CHZ specimens after hydration (HCHZ) was 5 wt%. As the zeolite proportion increased beyond 20 wt%, [Al(OH)4]- tended to react with [SiO(OH)3]- to form aluminosilicate gel instead of AFmc. After carbonation curing (CO2 concentration, 99%; gas pressure, 0.2 MPa; curing time, 2 h), the compressive strength of CHZ specimens (CCHZ) improved by 14–34% compared with that of pure CH specimens. An amorphous phase/calcite ratio of approximately 0.21 might produce an optimum strength resistance property in CCHZ. The heat released from the carbonation was beneficial for the polycondensation reaction of amorphous aluminosilicate to partially form Si[OSi]4 or Al[OSi]4 structures.

Comparison of Phenolic and Flavonoid Content and Antioxidant and Chelating Activities of Rhizophora mangle in Different Anthropogenically-Polluted Coastal Lagoons

The production of total phenolic content (TPC) and total flavonoid content (TFC), antioxidant (AA), and copper chelating (CACu+) activities of Rhizophora mangle from three coastal lagoons under different grades of anthropogenic pollution and pollutant presence were analyzed. R. mangle is a mangrove plant that inhabits tropical coastal lagoons and shows the ability to accumulate pollutants in their tissues and respond to environmental stressors via the production of secondary metabolites AA and CACu+ activities. In total, 108 samples (June 2010 to August 2011) of leaves, barks, and the roots of R. mangle from Magdalena Bay (MBAY), Navachiste Lagoon (NLAG), and Terminos Lagoon (TLAG) (Mexico) were collected. Folin-Ciocalteu colorimetric, aluminum chloride colorimetric, ABTS∙+ discoloration, and pyrocatechol-violet methods calculated TPC, TFC, AA, and, CACu+, respectively. Atomic absorption spectrometry, gas chromatography, and Walkley–Black methods were used to calculate the metal content, organochlorine pesticides (OCPs), and organic matter (OM) in sediments. One-way ANOVA and post hoc Tukey’s, Scheffé’s, and Bonferroni and Holm multiple comparisons were used to determine significance, and Pearson’s test was applied to determine the coefficient of correlations. Significant differences among the lagoons of TPC, TFC, AA, and Cu+CA activities of Rhizophora mangle are explained by their different grades and type of anthropogenic pollution. A significant increase in the TPC and TFC in bark implies a response to the metal and OCPs pollution in surrounding sediments. Significant AA and Cu+CA activities responded to combat environmental stress conditions caused by the OCP and trace metal concentrations in surrounding sediments. Strong and positive correlations among OCP and trace metal were found and related to the constant pesticide residues input. However, OCP concentrations in the surrounding sediments of R. mangle trees did not influence the phenolic production of AA or the Cu+ CA. R. mangle is affected by the type of anthropogenic pollutants and was reflected in the bio-compounds production, antioxidant, and chelating activities related to the concentration of the metals in sediments.

Global warming readiness: Feasibility of enhanced biological phosphorus removal at 35 °C

Recent research has shown enhanced biological phosphorus removal (EBPR) from municipal wastewater at warmer temperatures around 30 °C to be achievable in both laboratory-scale reactors and full-scale treatment plants. In the context of a changing climate, the feasibility of EBPR at even higher temperatures is of interest. We operated two lab-scale EBPR sequencing batch reactors for > 300 days at 30 °C and 35 °C, respectively, and followed the dynamics of the communities of polyphosphate accumulating organisms (PAOs) and competing glycogen accumulating organisms (GAOs) using a combination of 16S rRNA gene metabarcoding, quantitative PCR and fluorescence in situ hybridization analyses. Stable and nearly complete phosphorus (P) removal was achieved at 30 °C; similarly, long term P removal was stable at 35 °C with effluent PO43-_P concentrations < 0.5 mg/L on half of all monitored days. Diverse and abundant Candidatus Accumulibacter amplicon sequence variants were closely related to those found in temperate environments, suggesting that EBPR at this temperature does not require a highly specialized PAO community. A slow-feeding strategy effectively limited the carbon uptake rates of GAOs, allowing PAOs to outcompete GAOs at both temperatures. Candidatus Competibacter was the main GAO, along with cluster III Defluviicoccus members. These organisms withstood the slow-feeding regime, suggesting that their bioenergetic characteristics of carbon uptake differ from those of their tetrad-forming relatives. Comparative cycle studies revealed higher carbon and P cycling activity of Ca. Accumulibacter when the temperature was increased from 30 °C to 35 °C, implying that the lowered P removal performance at 35 °C was not a direct effect of temperature, but a result of higher metabolic rates of carbon (and/or P) utilization of PAOs and GAOs, the resultant carbon deficiency, and escalated community competition. An increase in the TOC-to-PO43−-P ratio (from 25:1 to 40:1) effectively eased the carbon deficiency and benefited PAOs. In general, a slow-feeding strategy and sufficiently high carbon input benefited a high and stable EBPR at 35 °C, representing basic conditions suitable for full-scale treatment plants experiencing higher water temperatures.

Metasomatic modification of Sr isotopes in apatite as a function of fluid chemistry

Apatite is a ubiquitous accessory mineral in crustal rocks. The Sr-isotope record of apatite has a wide range of applications in earth science studies. However, apatite has been documented to be easily altered by certain fluids. Currently, the impact of metasomatic alteration on Sr-isotopic abundances in apatite is not well known. In order to better understand this issue, well-characterized fluorapatite grains have been metasomatized experimentally at a temperature of 800 or 600 °C and a pressure of 200 MPa. Fluids used included a CO2-H2O mixture and NaF-, CaCl2-, and HCl-bearing solutions, all of which were doped with a standard solution with a known 87Sr/86Sr ratio. In the fluorapatite + CO2-H2O experiments, the fluorapatite grains were not altered by the fluids; thus, their Sr isotope compositions were generally kept unchanged. However, the other fluids induced partial to complete alteration of fluorapatite. In experiments involving the NaF- or HCl-bearing solutions, the Sr content remained constant or was increased in altered areas of the fluorapatite, and the Sr isotopes underwent changes with partial isotopic signature of the reacting solutions. In experiments involving CaCl2, the Sr content was decreased in the altered fluorapatite because high Ca activity in the solution caused Ca to replace Sr on the Ca site. Notably, the Sr isotopic ratios are still changed, although to a relatively small extent. The efficient Sr isotopic exchange between fluid and apatite is attributed to the rapid transport rate of Sr between the reaction-interface fluid and bulk fluid surrounding the apatite. This experimental study demonstrates that the response of apatite Sr isotopes to metasomatic alteration is mainly controlled by the chemistry of fluids. Overall, Sr isotopes become susceptible to hydrothermal alteration once the apatite is chemically reactive with the fluids. Therefore, it is important to evaluate the fluid-rock history, especially the conjectured fluid composition before using Sr isotopes from apatite as a geochemical tracer.

Changes in the Mitochondrial Dynamics and Functions Together with the mRNA/miRNA Network in the Heart Tissue Contribute to Hypoxia Adaptation in Tibetan Sheep.

Simple SummaryLong-term exposure to hypoxia, a major source of cellular stress, can induce hypoxia-related diseases and even death. Mitochondria play an important role in mediating the energy production response to hypoxia, but little is known about the mechanisms involved. Tibetan sheep are mainly distributed across the Qinghai–Tibet Plateau, where they have adapted well to hypoxia after long-term adaptation. In this work, a systematic analysis of the blood indexes, tissue morphology, mRNA and miRNA expression regulation, and changes in the mitochondrial function of Tibetan sheep at different altitudes was carried out to provide insights into the mechanism of animal adaptation to hypoxia and the progression of hypoxia-related illness.This study aimed to provide insights into molecular regulation and mitochondrial functionality under hypoxia by exploring the mechanism of adaptation to hypoxia, blood indexes, tissue morphology, mRNA/miRNA regulation, mitochondrial dynamics, and functional changes in Tibetan sheep raised at different altitudes. With regard to blood indexes and myocardial morphology, the HGB, HCT, CK, CK-MB, LDH, LDH1, SOD, GPX, LDL level, and myocardial capillary density were significantly increased in the sheep at higher altitudes (p < 0.05). The RNA-seq results suggested the DEmRNAs and DEmiRNAs are mainly associated with the PI3K-Akt, Wnt, and PPAR signaling pathways and with an upregulation of oncogenes (CCKBR, GSTT1, ARID5B) and tumor suppressor factors (TPT1, EXTL1, ITPRIP) to enhance the cellular metabolism and increased ATP production. Analyzing mRNA–miRNA coregulation indicated the mitochondrial dynamics and functions to be significantly enriched. By analyzing mitochondrial dynamics, mitochondrial fusion was shown to be significantly increased and fission significantly decreased in the heart with increasing altitude (p < 0.05). There was a significant increase in the density of the mitochondria, and a significant decrease in the average area, aspect ratio, number, and width of single mitochondrial cristae with increasing altitudes (p < 0.05). There was a significant increase in the NADH, NAD+ and ATP content, NADH/NAD+ ratio, and CO activity, while there was a significant decrease in SDH and CA activity in various tissues with increasing altitudes (p < 0.05). Accordingly, changes in the blood indexes and myocardial morphology of the Tibetan sheep were found to improve the efficiency of hemoglobin-carrying oxygen and reduce oxidative stress. The high expression of oncogenes and tumor suppressor factors might facilitate cell division and energy exchange, as was evident from enhanced mitochondrial fission and OXPHOS expression; however, it reduced the fusion and TCA cycle for the further rapid production of ATP in adaptation to hypoxia stress. This systematic study has for the first time delineated the mechanism of hypoxia adaptation in the heart of Tibetan sheep, which is significant for improving the ability of the mammals to adapt to hypoxia and for studying the dynamic regulation of mitochondria during hypoxia conditions.

Properties and Microstructure of Na2CO3-Activated Binders Modified with Ca(OH)2 and Mg(OH)2.

Delayed strength development and long setting times are the main disadvantageous properties of Na2CO3-activated slag cements. In this work, combined auxiliary activators of Ca(OH)2 and Mg(OH)2 were incorporated in one-part Na2CO3-activated slag binders to accelerate the kinetics of alkali activation. The properties and microstructure evolution were investigated to clarify the reaction mechanism. The results showed that the additions of auxiliary activators promoted the hardening of the pastes within 2 h. The 28 days compressive strengths were in the range of 39.5–45.5 MPa, rendering the binders practical cementitious materials in general construction applications. Ca(OH)2 was more effective than Mg(OH)2 in accelerating the kinetics of alkali activation. The dissolution of Ca(OH)2 released more OH− and Ca2+ ions in the aqueous phase to increase alkalinity in the aqueous phase and promote the formation of the main binding gel phase of calcium-aluminosilicate hydrate (C-A-S-H). An increase in the Ca(OH)2/Mg(OH)2 ratios increased autogenous shrinkage and decreased drying shrinkage of the binders. The formation of a compact pore structure restricted the water evaporation from the binders during the drying procedure.

STUDY OF BIOCHEMICAL MARKERS OF OSTEOGENESIS IN CASE OF BONE ALLOGRAFTS INCORPORATION IN RATS WITH FOLLOWED AFTER SURGERY ADMINISTRATION OF CISPLATIN AT THE DIFFERENT METHODS OF IMPLANT STERILIZATION

Bone allografts are commonly used for surgical treatment of cancer patients. However, such complications as violation of allograft fusion, its lysis and fractures, infection lead to additional research in this field of medicine. Objective. To study changes in biochemical osteogenesis markers under the action of cytostatics on the process of incorporation of bone allografts. Methods. The work was performed on 20 male white rats (age at the beginning of the experiment 5–6 months). All animals have a perforated defect in the distal metaphysis of the femur filled with bone allograft (diameter 2 mm, height 3 mm), γ-radiation sterilized (Control-1 and Experiment-1) or saturation of the antibiotics sterilized (Control-2 and Experiment-2). In groups «Control» 14 days after implantation intraperitoneally injected 2.0–2.4 ml of 0.9 % sodium chloride solution, in the groups «Experiment» — cisplatin at a dose of 2.5 mg/ kgonce. 30 days after surgery, blood glycoproteins, total protein, Ca, chondroitin sulfates, acidic and alkaline phosphatase activity were evaluated. The index of mineralization (ratio of alkaline to acid phosphatases), degree is analyzed mineralization (ratio of calcium to protein). Results. In the experimental groups, compared with the control, a significant decrease in total protein and values was determined: total calcium, which indicates the suppression of processes mineralization during remodeling of bone tissue of the recipient and allograft. The highest indicators of activity acid phosphatase were recorded in groups Experiment-1 and Experiment-2, reflecting the predominance of resorption over bone formation. The degree of mineralization in the experimental groups was higher than in the control, and the mineralization index was significantly smaller. Conclusions. The detected changes in the values of biochemical markers of bone metabolism reflect the negative effect of cisplatin on osteogenesis under the conditions of allograft implantation, which leads to the lack of their fusion with the recipient bone.