Reaction Products Research Articles

Modeling the Combustion-Deflagration-Detonation Transition (CoDDT) in a porous high explosive, comparison with experiments

ABSTRACT A reactive multiphase model stemming from the Baer and Nunziato model was developed and extended to three phases, one solid and two gaseous respectively representing the solid explosive, the initial porosity and the reaction products. It was used to model the transition from deflagration to detonation of a highly confined porous HMX 150–200 explosive thermally initiated, for several initial densities, ranging from 65% to 88% of the material's Theoretical Maximum Density (TMD). The influence of the deconsolidative burning in the critical acceleration of the reactive front was implemented through a fluidization parameter, allowing to switch from pore to grain burning. Other microstructural parameters such as the pores and grains size were determined by careful experimental characterizations presented in Bouchet et al. (2022). The model then succeeded in reproducing the physical mechanisms that were previously experimentally observed, such as the convective burning, the plug formation, and the transition to detonation at the distances that were experimentally measured.

Mutual Transformations of Polysulfide Chromophore Species in Sodalite‐Group Minerals: A DFT Study on S6 Decomposition

AbstractIt is known that various polysulfide species determine the color of sodalite‐group minerals (haüyne, lazurite, and slyudyankaite), and that heating induces their transformations and color change, but the mechanisms of the transitions are unknown. A prominent example is the decay of cyclic S6 molecule. Using density‐functional simulations, we explore its main decay pathways into the most probable final reaction products (the pairs of radical anions S3⋅−+S3⋅− and S2⋅−+S4⋅−). It was found that the most favorable reaction path involves initial capture of one electron by the S6 molecule, which greatly facilitates its decay of S6 and leads to the opening of the S6 cycle, and subsequent decomposition of the thus formed chain radical anion, with a limiting energy barrier of ~0.4 eV. Neutral polysulfide molecules capture one electron with a significant energy reduction. The radical anions Sn⋅− (n=2−6) are the most stable ones among corresponding species with the same n values and different charges. The capture of the second electron by S6⋅− occurs with a huge energy barrier (~2 eV). The results of the DFT calculations are in agreement with experimental data on the products of thermal conversions of extra‐framework S‐bearing groups in sodalite‐group minerals.

Development of a Superhydrophobic Protection Mechanism and Coating Materials for Cement Concrete Surfaces.

In order to further enhance the erosion resistance of cement concrete pavement materials, this study constructed an apparent rough hydrophobic structure layer by spraying a micro-nano substrate coating on the surface layer of the cement concrete pavement. This was followed by a secondary spray of a hydroxy-silicone oil-modified epoxy resin and a low surface energy-modified substance paste, which combine to form a superhydrophobic coating. The hydrophobic mechanism of the coating was then analysed. Firstly, the effects of different types and ratios of micro-nano substrates on the apparent morphology and hydrophobic performance of the rough structure layer were explored through contact angle testing and scanning electron microscopy (SEM). Subsequently, Fourier transform infrared spectroscopy and permeation gel chromatography were employed to ascertain the optimal modification ratio, temperature, and reaction mechanism of hydroxy-silicone oil with E51 type epoxy resin. Additionally, the mechanical properties of the modified epoxy resin-low surface energy-modified substance paste were evaluated through tensile tests. Finally, the erosion resistance of the superhydrophobic coating was tested under a range of conditions, including acidic, alkaline, de-icer, UV ageing, freeze-thaw cycles and wet wheel wear. The results demonstrate that relying solely on the rough structure of the concrete surface makes it challenging to achieve superhydrophobic performance. A rough structure layer constructed with diamond micropowder and hydrophobic nano-silica is less prone to cracking and can form more "air chamber" structures on the surface, with better wear resistance and hydrophobic performance. The ring-opening reaction products that occur during the preparation of modified epoxy resin will severely affect its mechanical strength after curing. Controlling the reaction temperature and reactant ratio can effectively push the modification reaction of epoxy resin through dehydration condensation, which produces more grafted polymer. It is noteworthy that the grafted polymer content is positively correlated with the hydrophobicity of the modified epoxy resin. The superhydrophobic coating exhibited enhanced erosion resistance (based on hydrochloric acid), UV ageing resistance, abrasion resistance, and freeze-thaw damage resistance to de-icers by 19.41%, 18.36%, 43.17% and 87.47%, respectively, in comparison to the conventional silane-based surface treatment.

High serological and molecular prevalence of Ehrlichia canis and other vector-borne pathogens in dogs from Boa Vista Island, Cape Verde

Despite the high global impacts of canine vector-borne diseases (CVBD) due to their wide distribution and zoonotic potential, the current epidemiological situation of CVBD in many tropical and subtropical regions remains unknown. This study examines the seroprevalence and molecular prevalence of Ehrlichia canis and other pathogens causing CVBDs (Leishmania infantum, Dirofilaria immitis, Babesia spp., Anaplasma spp. and Hepatozoon canis) in dogs living on the island of Boa Vista (Cape Verde Republic). Blood samples and infesting ticks were taken from 150 dogs across the island (stray, shelter, and pet dogs). Serum samples were tested using a rapid immunochromatographic test (Uranotest® Quattro) that detects antibodies against E. canis, L. infantum, Anaplasma spp. and D. immitis antigen. Levels of serum antibodies against E. canis were measured using the immunofluorescence antibody test (IFAT). In addition, tick-borne pathogens in blood samples (Anaplasma spp., Babesia spp., Hepatozoon spp., and Ehrlichia canis) were detected by microscopy observation and/or PCR plus sequencing. The seroprevalence of E. canis was extremely high at 82% (123/150), as revealed by both immunochromatography and IFAT. Most dogs returning a seropositive test result (82.92%; 102/123) had antibody titres > 1:1280 but showed no clinical signs or notable laboratory abnormalities. Of the 123 animals testing seropositive for E. canis, 67 (54.47%) also presented antibodies against Anaplasma spp., and 13 (10.56%) showed the presence of Hepatozoon spp. gamonts in the blood smear. Ehrlichia canis infection was detected in 17.1% (25/146) of dogs tested by direct sequencing of polymerase chain reaction (PCR) products. Co-infections were detected in seven of these dogs: four dogs tested PCR-positive for both E. canis and A. platys, two dogs tested positive for E. canis and Hepatozoon spp., and one dog tested positive for E. canis, A. platys and Hepatozoon spp. Rhipicephalus sanguineus sensu lato was the only tick species found infesting the canine study population. The high prevalence of tick-borne pathogens detected in dogs from Boa Vista Island highlights a need for improved control measures designed to prevent the transmission of these pathogens.Graphical

Rational design of anthocyanidins-directed near-infrared two-photon fluorescent probes.

Recently, two-photon fluorescent probes based on anthocyanidin molecules have attracted extensive attention due to their outstanding photophysical properties. However, there are only a few two-photon excited fluorescent probes that really meet the requirements of relatively long emission wavelengths (>600 nm), large two-photon absorption (TPA) cross-sections (300 GM), significant Stokes shift (>80 nm), and high fluorescence intensity. Herein, the photophysical properties of a series of anthocyanidins with the same substituents but different fluorophore skeletons are investigated in detail. Compared with b-series molecules, a-series molecules with a six-membered ring in the backbone have a slightly higher reorganization energy. This results in more energy loss upon light excitation, enabling the reaction products to detect NTR through a larger Stokes shift. More importantly, there is very little decrease in fluorescence intensity as the Stokes shift increases. These features are extremely valuable for high-resolution NTR detection. In light of this, novel 2a-n (n = 1-5) compounds are designed, which are accomplished by inhibiting the twisted intramolecular charge transfer (TICT) effect through alkyl cyclization, azetidine ring and extending π conjugation. Among them, 2a-3 gains a long emission spectrum (λem = 691.4 nm), noticeable TPA cross-section (957 GM), and large Stokes shift (110 nm), indicating that it serves as a promising candidate for two-photon fluorescent dyes. It is hoped that this work will offer some insightful theoretical direction for the development of novel high performance anthocyanin fluorescent materials.

Molecular modelling of luciferyl adenylate deprotonation in the active site of Photinus pyralis luciferase

Firefly bioluminescence is a product of chemical reactions that involve luciferin chromophore oxidation in the active site of luciferase proteins. We perform a series of classical molecular dynamic simulations and combined quantum and molecular mechanics (QM/MM) calculations to expose the molecular mechanism of C4 carbon atom deprotonation in luciferyl adenylate molecule. QM/MM calculations confirm that ND-protonated His245 residue is a suitable proton acceptor in the wild-type Photinus pyralis luciferase. Classical molecular dynamic simulations reveal oxygen-binding cavities inside the protein including the one located close to the C4 atom of luciferin. In mutant forms that lack direct interactions with the His245 side chain, a proton wire comprising water molecules stimulates either protonation of the phosphate group of the luciferyl adenylate forming an unstable intermediate or keto–enol tautomerisation of luciferin. The comparison of the ionisation potentials of molecular systems with the ‘deprotonated’ C4 carbon atom revealed that the ionisation energy for the enol tautomeric form is close to the system with the His245 proton acceptor. Thus, the existence of the keto–enol tautomerisation channel might explain bioluminescence in case of the absence of the amino acid proton acceptor.

Identifying Quinones in Complex Aqueous Environmental Media (Biochar Extracts) through Tagging with Cysteine and Cysteine-Contained Peptides and High Resolution Mass Spectrometry Analysis.

Quinones are among the most important components in natural organic matter (NOM) for redox reactions; however, no quinones in complex environmental media have been identified. To aid the identification of quinone-containing molecules in ultracomplex environmental samples, we developed a chemical tagging method that makes use of a Michael addition reaction between quinones and thiols (-SH) in cysteine (Cys) and cysteine-contained peptides (CCP). After the tagging, candidates of quinones in representative aqueous environmental samples (water extractions of biochar) were identified through high-resolution mass spectrometry (HRMS) analysis. The MS and UV spectra analysis showed rapid reactions between Cys/CCP and model quinones with β-carbon from the same benzene ring available for Michael addition. The tagging efficiency was not influenced by other co-occurring nonquinone representative compounds, including caffeic acid, cinnamic acid, and coumaric acid. Cys and CCP were used to tag quinones in water extractions of biochars, and possible candidates of quinones (20 and 53 based on tagging with Cys and CCP, respectively) were identified based on the HRMS features for products of reactions with Cys/CCP. This study has successfully demonstrated that such a Michael addition reaction can be used to tag quinones in complex environmental media and potentially determine their identities. The method will enable an in-depth understanding of the redox chemistry of NOM and its critical chemical compositions and structures.

DEVELOPMENT OF AN ALGORITHM FOR CALCULATING THE RATE CONSTANT OF HYDROCHLORIC ACID REACTION WITH A CARBONATE ROCK FORMATION

One of the main factors reducing acid stimulation efficiency is the intensive reaction of active acid in the immediate vicinity of the wellbore, which leads to insufficient completeness of reservoir rock dissolution in the remote reservoir zone. The reservoir hydrodynamic characteristics are not being improved properly, and the efficiency of oil production stimulation measures does not reach the planned values.To get high results of acid treatments it is necessary to achieve deep penetration of acid into the formation thickness. The reaction rate constant is used to compare the reactivity of different acid compositions and to select the most suitable acid composition for the geological and physical conditions of the treated object, which provides the highest treatment efficiency. It relates the initial substances concentrations with reaction products formation rate. To determine the reaction rate constant, a volumetric apparatus was created and methodological aspects were developed to work on it, allowing to minimize the measurement error and to achieve the greatest accuracy in determining the kinetic parameters of the reaction. But in the course of further investigations in the work of the existing algorithm for experimental data processing, a number of significant deficiencies distorting the results of calculations were revealed. The aim of the research is to develop a new improved algorithm for reaction rate constant calculation, which will improve the understanding of the process of determining the kinetic parameters of acid reaction with carbonate rock.To achieve this aim, the authors conducted a series of experiments according to the unified methodology, the results of which revealed ways to eliminate the identified deficiencies using a new algorithm. It includes obtaining and saving initial data, subsequent treatment and direct calculation of reaction kinetic parameters with results saving.The developed algorithm makes it possible to unify and automate the process of determining the kinetic parameters of the acid reaction with the formation rock, as well as to determine the reaction characteristics with higher accuracy and reduce the influence of the human factor on the research results, thus reducing the errors of the calculation results.

Reproducing Reaction Mechanisms with Machine‐Learning Models Trained on a Large‐Scale Mechanistic Dataset

AbstractMechanistic understanding of organic reactions can facilitate reaction development, impurity prediction, and in principle, reaction discovery. While several machine learning models have sought to address the task of predicting reaction products, their extension to predicting reaction mechanisms has been impeded by the lack of a corresponding mechanistic dataset. In this study, we construct such a dataset by imputing intermediates between experimentally reported reactants and products using expert reaction templates and train several machine learning models on the resulting dataset of 5,184,184 elementary steps. We explore the performance and capabilities of these models, focusing on their ability to predict reaction pathways and recapitulate the roles of catalysts and reagents. Additionally, we demonstrate the potential of mechanistic models in predicting impurities, often overlooked by conventional models. We conclude by evaluating the generalizability of mechanistic models to new reaction types, revealing challenges related to dataset diversity, consecutive predictions, and violations of atom conservation.

Trapping Highly Reactive Metal(H)2(η2‐H2) Species to Form Trihydride Complexes and Clusters

AbstractMetal dihydride dihydrogen‐derived intermediates can be short‐lived and difficult to detect despite their ubiquitous role in chemical transformations such as hydrogenation. Here, highly reactive [Ir(H)3(η2‐η2‐COD)(IMes)] forms by trapping [Ir(H)2(η2‐H2)(η2‐η2‐COD)(IMes)]X [X=Cl or MeO], resulting from reaction of the Ir(I) precatalyst [IrCl(η2‐η2‐COD)(IMes)] with a base and H2. This trihydride allows access to the unusual [Ir2(H)4(OMe)(IMes)2(pyridine)3]X, [Ir2(H)2(μ2‐H)2(η2‐η2‐COD)(IMes)2], [Ir3(H)9(IMes)3], [Ir4(H)12(IMes)4] and [Ir2(H)4(μ2‐H)2(IMes)2(pyridine)2]. A combination of 2D NMR, parahydrogen hyperpolarized NMR, MS, and XRD are used to characterise these reaction products and rationalise their formation via the moiety {Ir(H)3(IMes)}. Consequently, the results of these studies have implications for iridium‐catalyzed polarization transfer from parahydrogen via the well‐known precursor [IrCl(η2‐η2‐COD)(IMes)].

Strength characteristics and solidification carbonization mechanism of MgO based shield tunneling centrifugal waste silt

In response to the problem of the accumulation of waste silt produced by slurry shield tunneling, which is difficult to directly utilize, MgO carbonization acceleration technology is adopted. Carbonization modification equipment is used to test the water content (w) and unconfined compression strength (UCS) of waste silt produced by slurry shield tunneling under different soil curing agent content (as), curing time (T), and carbonization time (t). The strength characteristics of the process of MgO solidification carbonization shield tunneling centrifugal waste silt were clarified. The micro mechanism was revealed and its engineering usability was also explored. The results show that MgO cooperated with carbonization acceleration technology can improve the properties of waste silt, with a maximum decrease of 9.3%~31.7% and UCS can be increased to a maximum of 776.8 kPa. The maximum UCS of MgO solidified carbonized silt was higher than that of CaO solidified carbonized silt at various contents. Under the condition of T=7d, by comparing UCS, it was concluded that MgO carbonated solidified silt is more suitable for building foundation filling. And as =7% while t=1h modified silt can meet the strength requirement of 180 kPa under the condition of small MgO content. An improved three-phase model diagram of MgO solidification carbonation process based on water conversion research has been proposed for centrifugal high liquid limit silt in slurry shield tunneling. It can be divided into three stages: solidification reinforcement, carbonation reinforcement, and carbonation deepening, with strength growth mainly concentrated in the solidification reinforcement stage. During the solidification process, the hydration product Mg(OH)₂ and the reaction products MSH and MAH from the pozzolanic reaction are gradually transferred into various carbonization products, These products agglomerated and bonded with each other to form a whole, enhancing the bonding strength between particles and improving the strength of the silt. During the carbonization process, it is necessary to avoid the strength reduction caused by too long carbonization time.

Photochemical Dimerization of Indones: A DFT Study

In this study, DFT calculations were performed in order to identify the reaction products of the photochemical dimerization of indones. Calculations allowed us to assume that all tested reactions occurred in the first excited singlet state. The irradiation of 2-phenyl-5-nitroindone gave the main product, the <i>anti-cis</i> head-to-tail dimer, while the other two compounds found in the experiments were the <i>syn-cis</i> head-to-head dimer and the <i>anti-cis</i> head-to-tail dimer. The irradiation of 2-phenylindone gave the main product, <i>syn-cis</i>-head-to-tail dimer, while the minor products were <i>anti-cis</i>-head-to-tail and <i>anti-cis</i>-head-to-head dimer. The photochemical dimerization of 2-methyl-3-phenylindone gave the main product, <i>anti-cis</i>-head-to-tail dimer, while the minor component of the mixture was <i>syn-cis</i>-head- to-head dimer.

Sensorial flavor characteristics and volatile Maillard reaction products of Tenebrio molitor mealworm based-reaction flavors with beef broth-like flavor

Sensorial flavor characteristics and volatile Maillard reaction products of Tenebrio molitor mealworm based-reaction flavors with beef broth-like flavor

Reproducing Reaction Mechanisms with Machine-Learning Models Trained on a Large-Scale Mechanistic Dataset.

Mechanistic understanding of organic reactions can facilitate reaction development, impurity prediction, and in principle, reaction discovery. While several machine learning models have sought to address the task of predicting reaction products, their extension to predicting reaction mechanisms has been impeded by the lack of a corresponding mechanistic dataset. In this study, we construct such a dataset by imputing intermediates between experimentally reported reactants and products using expert reaction templates and train several machine learning models on the resulting dataset of 5,184,184 elementary steps. We explore the performance and capabilities of these models, focusing on their ability to predict reaction pathways and recapitulate the roles of catalysts and reagents. Additionally, we demonstrate the potential of mechanistic models in predicting impurities, often overlooked by conventional models. We conclude by evaluating the generalizability of mechanistic models to new reaction types, revealing challenges related to dataset diversity, consecutive predictions, and violations of atom conservation.

12-Nor-rotenoids and other cytotoxic constituents of Pachyrhizus erosus seeds

Five previously undescribed compounds, including three 12-nor-rotenoids, were isolated from Pachyrhizus erosus seeds. A brief survey on the dealkylation of selected rotenoids with BBr3 was undertaken. Spectroscopic data of these previously undescribed compounds and reaction products are reported. The proposal of absolute configurations at stereocenters in the isolates and reaction products was based on NMR and ECD data. Most of the isolates and reaction products were evaluated for their growth inhibitory activities against four cancer cell lines and a Vero cell line. Many compounds exhibited strong to moderate activities with IC50 values ranging from 0.06 to 20.9 μM, and their structure-activity relationships were evaluated.

Passivation of the positive electrode during the discharge of Li-O2 and O2-assisted Li-CO2 batteries: A comparative study

The effect of passivation of the positive electrode by solid products under discharge is assessed for the first time as one of the factors determining the discharge characteristics of Li-O2 (LOB) and oxygen-assisted Li-CO2 (LCOB) batteries. In order to estimate the passivation, the electrode surface coverage θ by the reaction product (Li2O2 or Li2CO3) is determined on the basis of a decrease in the double-layer capacitance value in the course of the discharge. It is shown that for a given amount of electricity, the electrode surface coverage by Li2CO3 in LCOB is 1.5–2 times that of the coverage by Li2O2 under discharge in LOB. Furthermore, for each of the batteries, achievement of the maximum discharge capacity does not result in the full electrode surface blocking by the discharge products. LCOB manifests higher discharge characteristics than LOB under the kinetic reaction control (in the 100–500 mA g−1 current density range), owing to the accelerated conversion of intermediates and slower solid reaction product deposition on a larger electrode surface area. As the current density increases from 500 to 2000 mA g−1, the discharge capacity of LOB and LCOB decreases, which is mainly due to the effect of diffusion limitations. Moreover, while in the case of LOB the parameter θ decreases, in the case of LCOB it is practically independent of the current density in the studied range. The latter effect may be due to increased passivating properties of Li2CO3 deposits formed under high current density. The results of the work allow considering θ as a new criterion for estimation of the discharge depth and for predicting the characteristics of LCOB and LOB.

Effective strategy for Cr(VI) removal from water in evolution process of ferroan brucite by redox and intercalation

Cr(VI)-contaminated wastewater treatment is of great significance to ecological environment and human health. In this work, ferroan brucite with different Fe2+ doping amounts (Mg1-XFeX(OH)2, x = 0.1–0.8) were synthesized for the removal of Cr(VI) from wastewater. The effect of Fe content, initial concentration of Cr(VI), reaction time, co-existing ions and pH for Cr(VI) removal performance were examined. As Fe2+ content increased, the removal efficiency initially increased and then decreased, Mg0.4Fe0.6(OH)2 exhibited the maximum removal amount of 494.63 mg/g. Kinetic studies showed Cr(VI) removal well fitted pseudo-second-order model and achieved equilibrium at approximately 40 min. Isotherm data was well described by Langmuir model. The coexisting ions except CO32− had negligible effect, while pH had a significant influence on Cr(VI) removal since different dominated form of Cr(VI) existed at different pH. The removal mechanism towards Cr(VI) under different pH values was explored. At acidic environment, most Cr(VI) in Cr2O72− was reduced to Cr(III) by Fe2+ resulting in the precipitation of (Fe,Mg)(Cr,Fe)2O4, the remaining part was immobilized by interlayer of reaction product LDHs, and the intercalation amounts of Cr2O72− were 114.05 mg/g and 106.78 mg/g at pH of 3 and 6. While under alkaline conditions, most CrO42− entered the interlayer of LDHs with amounts of 262.3 mg/g at pH = 11, and the rest was absorbed on the surface. Furthermore, the reaction product could be recovered as chromite with recovery rate of 83.94 %. The excellent removal performance suggested a promising strategy in sewage water remediation.

Three-dimensional phase field modeling, orientation prediction and stress field analyses of twin-twin, twin-grain boundary reactions mediated by disclinations in hexagonal close-packed metals

Crystalline defects, such as dislocations, disclinations, twins and grain boundaries, play critical roles in determining the mechanical properties of metals and alloys. In particular, with multiple competitive deformation modes activated, the mechanical behaviors of hexagonal close-packed metals are strongly influenced by the interactions and reactions of various types of defects. Despite extensive studies on the elastic interactions of defects, a theoretical framework capturing crystallographic reactions, especially reaction products and associated local stress concentration, is still unavailable. Here we suggest a disclination-based method to quantify defect reactions. By using a combination of crystallographic calculations and phase field modeling/simulations, twin-twin and twin-grain boundary reactions in hexagonal close-packed metals have been quantitatively analyzed. It has been found that partial disclinations, accompanied with other defects (e.g., {112¯6} and {112¯2} high-index twins), can be generated by defect reactions as typical byproducts. The orientation change and stress fields caused by disclination formation have been systematically calculated, which offers a rigorous mathematical foundation to explore twin-twin, twin-grain boundary reactions. By quantitatively determining defect reactions and local stress fields, our work provides new insights into the deformation mechanism and microstructure-property relationship in metallic materials.

Combustion synthesis of the (Ti,Zr)B2-(Zr,Ti)C eutectic composites: Structure formation and properties

The macrokinetic characteristics of combustion of the quaternary Ti-Zr-B-C mixture as well as the mechanism and stages of phase formation for the synthesis products were investigated. The mechanical and thermophysical properties of the hot-pressed boride/carbide ceramics with eutectic composition (Ti,Zr)B2-43%at.(Zr,Ti)C were measured. Preliminary mechanical alloying (MA) of the (Zr + Ti) mixture was shown to yield Ti/Zr granules having a laminar structure and consisting of alternating layers of titanium, zirconium, and (Zr,Ti)ss solid solution. The method used to prepare reaction mixtures and the initial temperature T0 increased within the range of 20–370 °C have virtually no effect on combustion temperature, which is 2260–2400 °C, while higher T0 increases the combustion rate by a factor of 1.5–2. The use of MA Ti/Zr granules reduces the combustion rate as well as the specific heat release amount and the heat release rate. Time-resolved X-ray diffraction data showed that binary carbides (Zr1-xTix)C and diborides (Ti1-yZry)B2 of variable stoichiometry are formed in the combustion wave of the Ti-Zr-B-C reaction mixtures within less than 0.25 s. The carbide and diboride phases are formed simultaneously; the use of MA Ti/Zr granules in the reaction mixtures reduces the content of solid solutions of variable stoichiometry among the reaction products. The ceramics fabricated using a combination of combustion synthesis and hot pressing have a dense and homogeneous structure that consist of bonded grains of the diboride (Ti0.80Zr0.20)B2 and carbide (Zr0.83Ti0.17)C phases having the following properties: density, 5.3 g/cm3; hardness, 22.9 GPa; fracture toughness, 4.7 MPa m0.5; heat capacity, 0.52 J/(g·K); thermal diffusivity, 11.67 mm2/s; and thermal conductivity, 33.28 W/(m·K).

Sodium Houttuyfonate Alleviates Monocrotaline-induced Pulmonary Hypertension by Regulating Orai1 and Orai2.

An increased intracellular Ca2+ concentration ([Ca2+]i) is a key trigger for pulmonary arterial smooth muscle cell (PASMC) proliferation and contributes greatly to pulmonary hypertension (PH). Extracellular Ca2+ influx via a store-operated Ca2+ channel, termed store-operated Ca2+ entry (SOCE), is a crucial mechanism for [Ca2+]i increase in PASMCs. Calcium release-activated calcium modulator (Orai) proteins, consisting of three members (Orai1-3), are the main components of the store-operated Ca2+ channel. Sodium houttuyfonate (SH) is a product of the addition reaction of sodium bisulfite and houttuynin and has antibacterial, antiinflammatory, and other properties. In this study, we assessed the contributions of Orai proteins to monocrotaline (MCT)-enhanced SOCE, [Ca2+]i, and cell proliferation in PASMCs and determined the effect of SH on MCT-PH and the underlying mechanism, focusing on Orai proteins, SOCE, and [Ca2+]i in PASMCs. Our results showed that: 1) Orai1 and Orai2 were selectively upregulated in the distal pulmonary arteries and the PASMCs of MCT-PH rats; 2) knockdown of Orai1 or Orai2 reduced SOCE, [Ca2+]i, and cell proliferation without affecting their expression in PASMCs in MCT-PH rats; 3) SH significantly normalized the characteristic parameters in a dose-dependent manner in the MCT-PH rat model; and 4) SH decreased MCT-enhanced SOCE, [Ca2+]i, and PASMC proliferation via Orai1 or Orai2. These results indicate that SH likely exerts its protective role in MCT-PH by inhibiting the Orai1,2-SOCE-[Ca2+]i signaling pathway.