Differential Mass Spectrometry Research Articles

Time-restricted feeding prevents memory impairments induced by obesogenic diet consumption, via hippocampal thyroid hormone signaling

ObjectiveThe early consumption of calorie-rich diet disrupts circadian rhythms and has adverse effects on memory, yet the effects of time-restricted feeding (TRF) and the underlying molecular mechanisms are unknown. Here, we set out to identify the behavioral and molecular circadian rhythms disruptions generated by juvenile obesogenic diet consumption and their restoration by TRF in male mice. MethodsMetabolic rhythms were measured by indirect calorimetry and memory performances by behavioral tasks. Hippocampal translatome (pS6_TRAP), enrichment and co-regulated gene network analyses were conducted to identify the molecular pathways involved in memory impairments and their restoration by TRF. Differential exon usage analyses, mass spectrometry and pharmacological intervention were used to confirm thyroid hormone signaling involvement. ResultsWe show that four weeks of TRF restore the rhythmicity of metabolic parameters and prevents memory impairments in mice fed a high fat-high sucrose (HFS) diet since weaning, independently of body fat levels. Hippocampal translatome and differential exon usage analyses indicate that impaired memory of mice under ad libitum HFS diet is accompanied by reduced thyroid hormone signaling and altered expression of astrocytic genes regulating glutamate neurotransmission. TRF restored the diurnal expression variation of part of these genes and intra-hippocampal infusion of T3, the active form of thyroid hormone, rescues memory performances and astrocytic gene expression of ad libitum HFS diet-fed mice. ConclusionsThus, thyroid hormones contribute to the TRF positive effects on both metabolism and memory in mice fed an obesogenic diet, highlighting this nutritional approach as a powerful tool in addressing obesity brain comorbidities and paving the way for further mechanistic studies on hippocampal thyroid signaling.

Study of the mechanisms of change in hydride phases in zirconium beryllide during its linear heating

Abstract Beryllides have a number of unique properties that make them promising for use in various fields of industry and energy. Since some of the beryllides have the potential to dissolve large amounts of hydrogen (in some cases forming hydride phases), there is some interest in evaluating their possible applications in hydrogen technologies. This paper presents the results of studies of changes in the phase composition of the zirconium beryllide deuteride compound during its linear heating. The studies were carried out using a complex method including thermal gravimetrical analysis (TGA), differential scanning calorimetry (DSC) and mass spectrometry. Based on the results of the experiments, a number of parameters were obtained characterizing the transitions of deuteride from the phase of the Orthorhombic I mma crystal structure of deuteride ZrBe2D into the Orthorhombic C mcm crystal structure of deuteride ZrBe2D0.67, as well as the decomposition parameters of Orthorhombic C mcm crystal structure of ZrBe2D0.67. The energies of endothermic reactions of the corresponding transitions and decompositions of deuteride phases were estimated, and the activation energy of the interaction of water vapor with the surface of zirconium beryllide samples was also estimated.

New Iron(III)-Containing Composite of Salinomycinic Acid with Antitumor Activity—Synthesis and Characterization

In this study we demonstrated for the first time synthetic procedures for composites of salinomycin (SalH) and two-line ferrihydrite. The products were characterized by various methods such as elemental analysis, attenuated total reflectance–Fourier-transform spectroscopy (ATR-FTIR), electron paramagnetic resonance spectroscopy (EPR), powder X-ray diffraction analysis (XRD), electrospray-ionization mass spectrometry (ESI-MS), thermogravimetric analysis with differential thermal analysis (DTA) and mass spectrometry (TG-DTA/MS). The EPR spectra of the isolated compounds consisted of signals associated with both isolated Fe3+ ions and magnetically coupled Fe3+ ions. Powder XRD analyses of the isolated products showed two intense and broad peaks at 9° and 15° 2Θ, corresponding to salinomycinic acid. Broad peaks with very low intensity around 35°, assigned to two-line ferrihydrite, were also registered. Based on the experimental results, we concluded that salinomycin sodium reacted with Fe(III) chloride to form composites consisting of two-line ferrihydrite and salinomycinic acid. One of the composites exerted pronounced antitumor activity in the sub-micromolar concentration range against human cervical cancer (HeLa), non-small-cell lung cancer (A549), colon cancer (SW480), and ovarian teratocarcinoma (CH1/PA1) cells.

The Reduction Reaction Behavior of Steelmaking Dusts with Lignin under Different Atmospheres.

This study investigated lignin as a reducing agent instead of fossil carbon for the reduction of zinc oxide and zinc ferrite contained in steelmaking dusts. Three types of dusts from different steelmaking processes were considered: ferrochrome converter (CRC), electric arc furnace stainless steel (EAFSS) and electric arc furnace carbon steel (EAFCS). Zinc is primarily found in zincite phases within CRC dust, while EAFSS and EAFCS dusts contain franklinite and zincite phases as Zn-bearing minerals. The proximate analysis of lignin showed that the fixed carbon content is 28.9%. Thermogravimetric (TG) analysis coupled with differential scanning calorimetry (DSC) and mass spectrometry (MS) was used to study the reduction behavior of different mixtures of lignin and steel dusts under inert and air atmospheres. Simultaneously, the minimum ratio of lignin out of three different proportions required to achieve a complete reduction of franklinite and zincite phases into metallic zinc was identified. The results indicated that a 1.1 stoichiometric amount of lignin is sufficient for the complete reduction of zinc-bearing minerals into metallic zinc. In conclusion, lignin can be used efficiently for processing steelmaking dusts.

Diagnostic and Prognostic Markers for Pancreatitis and Pancreatic Ductal Adenocarcinoma.

Diagnostic markers are desperately needed for the early detection of pancreatic ductal adenocarcinoma (PDA). We describe sets of markers expressed in temporal order in mouse models during pancreatitis, PDA initiation and progression. Cell type specificity and the differential expression of PDA markers were identified by screening single cell (sc) RNAseq from tumor samples of a mouse model for PDA (KIC) at early and late stages of PDA progression compared to that of a normal pancreas. Candidate genes were identified from three sources: (1) an unsupervised screening of the genes preferentially expressed in mouse PDA tumors; (2) signaling pathways that drive PDA, including the Ras pathway, calcium signaling, and known cancer genes, or genes encoding proteins that were identified by differential mass spectrometry (MS) of mouse tumors and conditioned media from human cancer cell lines; and (3) genes whose expression is associated with poor or better prognoses (PAAD, oncolnc.org). The developmental progression of PDA was detected in the temporal order of gene expression in the cancer cells of the KIC mice. The earliest diagnostic markers were expressed in epithelial cancer cells in early-stage, but not late-stage, PDA tumors. Other early markers were expressed in the epithelium of both early- and late-state PDA tumors. Markers that were expressed somewhat later were first elevated in the epithelial cancer cells of the late-stage tumors, then in both epithelial and mesenchymal cells, or only in mesenchymal cells. Stromal markers were differentially expressed in early- and/or late-stage PDA neoplasia in fibroblast and hematopoietic cells (lymphocytes and/or macrophages) or broadly expressed in cancer and many stromal cell types. Pancreatitis is a risk factor for PDA in humans. Mouse models of pancreatitis, including caerulein treatment and the acinar-specific homozygous deletion of differentiation transcription factors (dTFs), were screened for the early expression of all PDA markers identified in the KIC neoplasia. Prognostic markers associated with a more rapid decline were identified and showed differential and cell-type-specific expression in PDA, predominately in late-stage epithelial and/or mesenchymal cancer cells. Select markers were validated by immunohistochemistry in mouse and human samples of a normal pancreas and those with early- and late-stage PDA. In total, we present 2165 individual diagnostic and prognostic markers for disease progression to be tested in humans from pancreatitis to late-stage PDA.

Pt1.8Pd0.2CuGa Intermetallic Nanocatalysts with Enhanced Methanol Oxidation Performance for Efficient Hybrid Seawater Electrolysis.

Seawater electrolysis is a potentially cost-effective approach to green hydrogen production, but it currently faces substantial challenges for its high energy consumption and the interference of chlorine evolution reaction (ClER). Replacing the energy-demanding oxygen evolution reaction with methanol oxidation reaction (MOR) represents a promising alternative, as MOR occurs at a significantly low anodic potential, which cannot only reduce the voltage needed for electrolysis but also completely circumvents ClER. To this end, developing high-performance MOR catalysts is a key. Herein, a novel quaternary Pt1.8Pd0.2CuGa/C intermetallic nanoparticle (i-NP) catalyst is reported, which shows a high mass activity (11.13 A mgPGM -1), a large specific activity (18.13mA cmPGM -2), and outstanding stability toward alkaline MOR. Advanced characterization and density functional theory calculations reveal that the introduction of atomically distributed Pd in Pt2CuGa intermetallic markedly promotes the oxidation of key reaction intermediates by enriching electron concentration around Pt sites, resulting in weak adsorption of carbon-containing intermediates and favorable adsorption of synergistic OH- groups near Pd sites. MOR-assisted seawater electrolysis is demonstrated, which continuously operates under 1.23V for 240h in simulated seawater and 120h in natural seawater without notable degradation.

Understanding the Effects of Site-Specific Light Chain Conjugation on Antibody Structure Using Hydrogen Exchange-Mass Spectrometry (HX-MS)

Antibody drug conjugates (ADCs) represent one of the fastest growing classes of cancer therapeutics. Drug incorporation through site-specific conjugation in ADCs leads to uniform drug load and distribution. These site-specific modifications may have an impact on ADC quality attributes including protein higher order structure (HOS), which might impact safety and efficacy. In this study, we conducted a side-by-side comparison between the conjugated and unconjugated mAb. In the ADC, the linker-pyrrolobenzodiazepine was site specifically conjugated to an engineered unpaired C215 residue within the Fab domain of the light chain. Differential scanning calorimetry (DSC) and differential scanning fluorimetry (DSF) indicated a decrease in thermal stability for the CH2 transition of the ADC. Size exclusion chromatography (SEC) analysis showed that conjugation of the mAb resulted in earlier aggregation onset and increased aggregation propensity after 4 weeks at 40 °C. Differential hydrogen-exchange mass spectrometry (HX-MS) indicated that upon conjugation, light chain residues 150-155 and 197-204, close to the conjugation site, showed significantly faster HX kinetics, suggesting an increase in backbone flexibility within this region, while heavy chain residues 32-44 exhibited significantly slower kinetics, suggesting distal stabilization of the mAb backbone.

The Influence of Freezing-thawing on the Properties of Sludge from Water Treatment Facilities and the Prospects for its Disposal

It has been shown that the freezing-thawing method allows a sharp increase in the water-yielding capacity of water treatment sludge (WTS sludge) and leads to an increase in the median particle size of the dispersed phase of sludge. The distribution of bound water types in WTP sludge was studied using thermogravimetry (TG), differential thermal thermogravimetry (DTG), differential scanning calorimetry (DSC) and mass spectrometry of gaseous thermolysis products (MS). It has been established that the release of water and carbon dioxide is completely completed at a temperature of 600°C. The specific surface area of the solid phase of WTP sludge before and after freezing-thawing was determined. The pore size distribution was studied. The BET isotherm of WTP sludge corresponds to mesoporous sorbents.

Abstract CT194: N-myristoylation inhibitor zelenirstat: New mechanistic insights and efficacy signals from a first in human phase I study

Abstract Introduction. Zelenirstat (PCLX-001) is a small molecule inhibitor of N-myristoylation, a process that involves addition of the fatty acid myristate to over 200 proteins by two N-myristoyltransferases (NMT1 and 2). These include Src family kinases and c-Abl. Inhibition of N-myristoylation by zelenirstat leads to the degradation of non-myristoylated proteins and cancer cell death. We conducted a phase I trial to evaluate the safety, tolerability, and maximally tolerated dose (MTD) of zelenirstat in patients with refractory cancer. Methods. Differential mass spectrometry was performed in NMT1 and NMT2 CRISPR/Cas9 KOs or zelenirstat-treated HAP1 cells to identify N-myristoylation-regulated proteins. Fully consented patients with advanced solid malignancies or refractory B-cell lymphomas were administered escalating doses of zelenirstat in 28-day cycles until progression or dose-limiting toxicity (DLT). Results. Proteomic analysis of cells with genetic or pharmacological NMT inhibition was performed to gain insights into NMT substrates and function. In addition to the rapid degradation of SFKs, which disrupts the pro-survival signaling of RTKs, we identified multiple respiratory complex I proteins as the most degraded, including NDUFAF4. NMT1 KO and zelenirstat treatment disrupted complex I leading to oxidative phosphorylation (OXPHOS) inhibition, which is essential for both cancer stem cell survival and metastasis. Continuous once-daily zelenirstat at 20 mg to 210 mg was well tolerated, with no dose-limiting toxicities in 24 patients up to and including 210 mg. Gastrointestinal DLTs were observed in the 280 mg cohort, establishing 210 mg as the MTD. Oral absorption was rapid, and pharmacokinetics were suitable for once daily dosing. Seven patients had stable disease as best response, including pancreatic, ovarian and colon cancer patients; one colon cancer patient with 5 prior lines of therapy continues 210 mg beyond 11 cycles with reduction in carcinoembryonic antigen (CEA) and tumor dimensions. Kaplan-Meier analysis revealed longer progression-free survival (log-rank p=0.033) and overall survival (p=0.026) in the patients treated at 210 mg (n=7) when compared with patients treated in lower dose cohorts (n=17). Conclusion. Zelenirstat has a unique dual impact on growth signaling and OXPHOS. Having previously demonstrated pre-clinical efficacy in hematologic cancers in vitro and in vivo, we now demonstrate the therapeutic potential of zelenirstat in patients with refractory advanced solid malignancies, warranting further clinical evaluation in these indications. Citation Format: Luc Gerard Berthiaume, Erwan Beauchamp, Jay Gamma, Rony Pain, Morris A. Kostiuk, Christopher R. Cromwell, Eman W. Moussa, Olivier Julien, Basil P. Hubbard, John Kuruvilla, Laurie H. Sehn, Jennifer Spratlin, Rahima Jamal, Randeep Sangha, John R. Mackey. N-myristoylation inhibitor zelenirstat: New mechanistic insights and efficacy signals from a first in human phase I study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT194.

High-temperature interaction of water vapor with lithium ceramics Li2TiO3

Selection of materials for fusion reactors and, in particular, for blanket systems is one of the most important tasks that determine the development of fusion energy. Lithium ceramics Li2TiO3 is considered as prospective candidate for solid breeders of future fusion reactors' blankets. The paper presents the results of high-temperature tests of Li2TiO3 + 5 mol% TiO2 ceramics, performed under conditions of blowing with argon containing impurities of water vapor of different isotopic compositions (H2O, HDO, D2O) in the range of temperature from 100 °C to 1400 °C. The vapor–gas mixture for the experiment was prepared in a special mixing tank. The interaction of Li2TiO3 + 5 mol% TiO2 ceramics with chemically active gases and water vapors was investigated by thermogravimetry (TG), differential scanning calorimetry (DSC) and mass spectrometry (MS) methods. As a result of experiment, the dependences of the sample mass change during heating under single purge gas composition was obtained. Mass spectra that characterize the changes in the qualitative composition of the gas mixture in the reaction chamber with the investigated sample were recorded and subsequently analyzed. An isotope effect is observed during the experiment: the release of D2 gas begins significantly earlier than the release of HD gas. The observed effect appears only in the high-temperature region (above 1050 °C), which characterizes the investigated material as almost completely chemically neutral towards water vapor.

A comprehensive study of the thermal behavior of rare earth chloride hydrates: resolving contradictions

Rare earth metal chlorides are used as starting materials on electrochemical synthesis of pure metals. These chlorides are hygroscopic and tend to form hydrates. To resolve the uncertainty of the thermal behavior of the hydrates LaCl3 ∙ 7H2O, NdCl3 ∙ 6H2O, SmCl3 ∙ 6H2O, and YbCl3 ∙ 6H2O, a comprehensive study is carried out. Thermogravimetry, differential scanning calorimetry and mass spectrometry were used to reveal the dehydration and hydrolysis processes over the temperature range of 25–700 ºC. Phase compositions of the initial hydrates, intermediate and final products are investigated by the XRD analysis, Raman and IR spectroscopy. Distinctions in the thermal behavior of the studied hydrates were found. The features must be taken into account when obtaining anhydrous rare earth chlorides and in technological processes with its participation.

Vaporization processes and thermodynamic properties of the SrO-ZrO<sub>2 </sub> system at high temperatures

Vaporization processes and thermodynamic properties of the SrO-ZrO2 system in the concentration range from 10 to 90 mol% SrO were studied by high-temperature differential mass spectrometry. Evaporation of the studied samples were carried out from tungsten Knudsen effusion cell. Partial pressures of vapor species in the temperature range of 1975-2800 K were determined. The values of SrO and ZrO2 activities, as well as Gibbs energies and excess Gibbs energies in the composition range from 90 to 45 mol% SrO were obtained at the temperature of 1940 K and from 45 to 10 mol% SrO at the temperature of 2123 K. It is established that in the SrO-ZrO2 system minor negative deviations from ideal behavior are observed.

Nickel-based composites using tungsten carbides as enhancers for electroactivity for the hydrogen evolution reaction

This study explores the impact of incorporating tungsten carbides into a Watts bath on the fabrication of Ni/WC and Ni/W2C composites, comparing them with conventional Ni Watts electrodeposited electrodes. Results indicate that adding tungsten carbides to the conventional nickel bath forms rougher and more porous structures in the deposited composites. Composite electrodes exhibit significantly enhanced current density for hydrogen evolution in alkaline media compared to nickel Watts electrodes. Differential Electrochemistry Mass Spectrometry (DEMS) elucidates the hydrogen evolution mechanism, providing accurate data for Tafel plots. X-ray photoelectron spectroscopy (XPS) shows minimal impact on nickel's surface chemistry. X-ray diffractograms demonstrate that tungsten carbide particles maintain crystalline structure. X-ray dispersive spectroscopy (EDS) reveals an uneven chemical composition, with Ni/WC and Ni/W2C composites containing approximately 17% tungsten carbides. Electrochemical impedance spectroscopy (EIS) indicates higher electrochemical areas and lower charge transfer resistances in Ni/WC and Ni/W2C composites than in Ni Watts. This study contributes insights for the efficient and economical development of electrolysis systems. Notably, Ni/WC and Ni/W2C composites show promising electrochemical performance, emphasizing their potential in advancing electrolysis technology.

Metabolomic and Lipidomic Analysis of the Colorectal Adenocarcinoma Cell Line HT29 in Hypoxia and Reoxygenation.

The poor availability of oxygen and nutrients in malignant tumors drives the activation of various molecular responses and metabolic reprogramming in cancer cells. Hypoxic tumor regions often exhibit resistance to chemotherapy and radiotherapy. One approach to enhance cancer therapy is to indirectly increase tumor oxygen availability through targeted metabolic reprogramming. Thus, understanding the underlying metabolic changes occurring during hypoxia and reoxygenation is crucial for improving therapy efficacy. In this study, we utilized the HT29 colorectal adenocarcinoma cell line as a hypoxia-reoxygenation model to investigate central carbon and lipid metabolism. Through quantitative NMR spectroscopy and flow injection analysis - differential mobility spectroscopy-tandem mass spectrometry (FIA-DMS-MS/MS) analysis, we observed alterations in components of mitochondrial metabolism, redox status, specific lipid classes, and structural characteristics of lipids during hypoxia and up to 24 h of reoxygenation. These findings contribute to our understanding of the metabolic changes occurring during reoxygenation and provide the basis for functional studies aimed at metabolic pathways in cancer cells.

Differential Mobility Spectrometry-Tandem Mass Spectrometry with Multiple Ion Monitoring Coupled with in Source-Collision Induced Dissociation: A New Strategy for the Quantitative Analysis of Pharmaceutical Polymer Excipients in Rat Plasma.

Polylactic acids (PLAs) are synthetic polymers composed of repeating lactic acid subunits. For their good biocompatibility, PLAs have been approved and widely applied as pharmaceutical excipients and scaffold materials. Liquid chromatography-tandem mass spectrometry is a powerful analytical tool not only for pharmaceutical ingredients but also for pharmaceutical excipients. However, the characterization of PLAs presents particular problems for mass spectrometry techniques. In addition to their high molecular weights and wide polydispersity, multiple charging and various adductions are intrinsic features of electrospray ionization. In the present study, a strategy combining of differential mobility spectrometry (DMS), multiple ion monitoring (MIM) and in-source collision-induced dissociation (in source-CID) has been developed and applied to the characterization and quantitation of PLAs in rat plasma. First, PLAs will be fragmented into characteristic fragment ions under high declustering potential in the ionization source. The specific fragment ions are then screened twice by quadrupoles to ensure a high signal intensity and low interference for mass spectrometry detection. Subsequently, DMS technique has been applied to further reduce the background noise. The appropriately chosen surrogate specific precursor ions could be utilized for the qualitative and quantitative analysis of PLAs, which provided results with the advantages of low endogenous interference, sufficient sensitivity and selectivity for bioassay. The linearity of the method was evaluated over the concentration range 3-100 μg/mL (r2 = 0.996) for PLA 20,000. The LC-DMS-MIM coupled with in source-CID strategy may contribute to the pharmaceutical studies of PLAs and the possible prospects of other pharmaceutical excipients.

Chemical Characterization of Ultra High Molecular Weight Polyethylene Based Tibial Inserts After Ethylene Oxide Sterilization

Ultra-high molecular weight polyethylene (UHMWPE) has become the gold standard for total joint replacements such as tibial inserts because of its chemical inertness, superior mechanical properties, and biocompatibility. Ethylene oxide sterilization is one of the most common and effective methods used, especially for the sterilization of polyethylene-based polymeric implants. However, variable sterilization conditions can cause a change in the chemical structure of the polymeric material, which affects its mechanical properties and lifetime. The aim of this study is to investigate whether the chemical structure of UHMWPE tibial inserts sterilized with ethylene oxide undergoing certain conditions remains the same. Chemical characterization studies were performed with Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffractometer, differential scanning calorimetry, thermogravimetric analysis, mass spectrometry and elemental analysis techniques recommended for polymeric materials in ISO 10993-8:2020 standard. According to the FTIR results, the spectra of the non-sterile and sterile tibial inserts were compared, and it was determined that the similarity between them was 99.97%. XRD results revealed that after ethylene oxide sterilization, there was no significant shift in the Bragg (1 0 0) peak. The percentages of crystallinity calculated from the fusion enthalpies determined by DSC of sterile and non-sterile samples are 54.3% and 53.3%, respectively. Characterization results revealed that there was no significant change in molecular structure, crystallinity, elemental composition of UHMWPE materials after ethylene oxide sterilization. These results can provide assurance that tibial inserts keep their physical, chemical, and mechanical properties after sterilization.

Thermal decomposition of silver propionate

The thermal decomposition of silver propionate, C2H5COOAg, was investigated using X-ray diffraction (XRD), thermogravimetry combined with differential thermal analysis and mass spectrometry (TG-DTA-MS), and scanning electron microscopy (SEM). Thermal analysis (TG and DTA) showed single-step decomposition with a total mass loss of 40 and 38 % in air and in inert gas respectively, corresponding to complete transformation of the precursor to Ag. Silver particles of about 1 μm in size are formed on the edges of the silver propionate microcrystals at the initial stages of the thermal decomposition, while upon heating the sample above 270°C, the final product of the thermal decomposition is metallic silver with a size of 1–2 μm.

Mechano-covalent protection of coagulation factor VIII by von Willebrand factor.

von Willebrand factor (VWF) is the protective carrier of procoagulant factor VIII (FVIII) in the shear forces of the circulation, prolonging its half-life and delivering it to the developing thrombus. Using force spectroscopy, VWF-FVIII complex formation is characterized by catch-bond behavior in which force first decelerates then accelerates bond dissociation. Patients with mutations in VWF at the FVIII binding site phenocopies hemophilia A and the most common mutations are of cysteine residues involving multiple disulfide bonds. From differential cysteine alkylation and mass spectrometry experiments, 13 VWF disulfide bonds at the FVIII binding site were found to exist in formed and unformed states, and binding of FVIII results in partial formation of 12 of the VWF bonds. Force spectroscopy studies indicate that the VWF-FVIII bond stiffens in response to force and this feature of the interaction is ablated when VWF disulfide bonds are prevented from forming, resulting in slip-only bond behavior. Exposure of VWF to pathological fluid shear forces exvivo and invivo causes partial cleavage of all 13 disulfide bonds, further supporting their malleable nature. These findings demonstrate that FVIII binding to VWF involves dynamic changes in the covalent states of several VWF disulfides that are required for productive interaction in physiological shear forces.

СИНТЕЗ И ИССЛЕДОВАНИЕ ФИЗИКО-ХИМИЧЕСКИХ И ТЕРМОДИНАМИЧЕСКИХ СВОЙСТВ В СИСТЕМЕ Na2O-BaO-B2O3

38 samples were synthesized in the Na2O-BaO-B2O3 system, some of which were glasses, some crystallized. The degree of interaction of the initial reagents in the synthesis process was controlled by X–ray phase analysis on a DRON-3M diffractometer using CuKa radiation. Crystal phases were identified using X–ray phase analysis on a DRON-3M diffractometer using CuKa radiation and the PDF–2 powder diffractometry database. The following crystalline phases were identified in the crystallized samples: β-BaВ2O4, NaBO2, NaBaB9O15. Density, microhardness, refractive index were measured for glassy samples of the system under study and melting/liquidus temperatures were determined. It is established that the nature of the dependence of the above properties on the content of sodium oxide with a constant content of boron oxide is linear. The study of vaporization processes and thermodynamic properties of the Na2O-BaO-B2O3 system was carried out by differential high-temperature mass spectrometry on the MS–1301 mass spectrometer. The studied samples were evaporated from a twin Knudsen molybdenum effusion cell. The heating of the cell was carried out by electronic bombardment, the temperature was measured with an optical pyrometer EOP–66. It was shown that as a result of the interaction of Na2O, BaO and B2O3 oxides, sodium and barium borates are formed in the condensed phase. It is established that the studied system is characterized by selective evaporation of NaBO2 in the temperature range of 1290–1350 K. The activity values of NaBO2 and B2O3 were determined depending on the composition of the condensed phase at a temperature of 1330 K. The activity of BaB2O4 was calculated using the Gibbs-Dugem equation. The obtained values of the Gibbs mixing energies and excess Gibbs energies indicate significant deviations of the Na2O-BaO-B2O3 system from the ideal behavior.

Kinetics and mechanism of oxidizing roasting of sulfide copper-cobalt ore

The aim of the study was to examine the chemistry, kinetics and mechanism of oxidizing roasting of a typical sample of sulfide copper-cobalt ore. The research object was sulfide copper-cobalt ore with the following main minerals: pyrite, pyrrhotite, chalcopyrite, sphalerite, tremolite, silicon dioxide, talc, siderite and calcite. The methodology involved high-temperature X-ray phase analysis (100–900°C), thermogravimetry, differential scanning calorimetry and mass spectrometry of the released gas (30–1100°C, heating rate – 5–20°C·min-1, air flow rate – 30 cm3·min-1). The chemistry, kinetics and mechanism of oxidizing roasting of sulfide copper-cobalt ore with a particle size of <0.1 mm were studied. It was found that the process can be represented as a set of seven elementary reactions: five exothermic reactions (at 398–445, 394–488, 440–498, 433–549 and 451–562°C), corresponding to the intense combustion of iron, copper and zinc sulfides, and two endothermic reactions (at 651–664 and 743–927°C), associated with the decomposition of residual copper and iron sulfates. Kinetic analysis (Kissinger and Augis-Bennett methods, identification of the reaction model by reference function and iterative optimization) of differential scanning calorimetry data in connection with the above reactions showed that the limiting stage of the latter is nucleation and crystal growth. The values of activation energy, pre-exponential factor and Avrami parameter ranged between 140–459 kJ·mol-1, 1.41·104–3.49·1031 with-1 and 1.0–1.7, respectively. It was established that crystallization of the products of elementary reactions is accompanied by an increase in the number of nuclei; new phase nuclei can be formed both on the surface and in the bulk of ore particles. The crystal growth is one-dimensional and is controlled by a chemical reaction at the interphase boundary or by diffusion of reagents. The results obtained can be applied in the practice of oxidizing roasting of sulfide ores and concentrates.