Thermogravimetry Differential Scanning Calorimetry Research Articles

Kinetics and Combustion Behavior of Atomized Zn-Mg Alloy Powder.

Using pyrolants instead of warhead charges can release red light and thick smoke for target practice to highlight the safety of the impact point and dud disposal. In order to find the ideal material, the combustion and kinetic properties of two Zn-Mg alloys at critical proportions were investigated. Thermogravimetry/differential scanning calorimetry (TG/DSC) experiments in pure oxygen were conducted with atomized Zn-Mg alloy powder in the ratio of 7:3 and the ratio of 8:2 with three particle diameters under different heating rates. The kinetic parameters of the six materials were obtained by ASTM E698 and Ozawa-Flynn-Wall (OFW) methods, indicating that the activation energy (Eα) of the 7:3 Zn-Mg alloy powder was lower than that of the 8:2 Zn-Mg alloy powder when the particle size distributions are similar. By the method of nonlinear multivariate regression, the oxidation reaction of Zn-Mg alloy powder was divided into two steps. The proportion of mass gain of the first-step reaction of 7:3 Zn-Mg alloy powder was 0.462-0.518, and the proportion of mass gain of the first-step reaction of 8:2 Zn-Mg alloy powder was 0.138-0.228. Reaction mechanism functions of the two-step reaction of Zn-Mg alloy oxidation were derived as f(α) = (1 - α)n(1 + kcat·α). The results of combustion experiments showed that the pyrolants composed of 7:3 alloy can burn stably to produce satisfactory smoke and light signals, while the pyrolants composed of 8:2 alloy cannot achieve this. The 7:3 Zn-Mg alloy powder is an ideal ingredient for pyrotechnic compositions.

Effect of Modified Halloysite/Expandable Graphite Addition on Thermal and Intumescent Properties of the Fire-Resistant Paints for Steel

The article presents results of the research on the influence of halloysite and its modified versions in a configuration with expandable graphite on thermal stability, integrity and intumescence of the fire-resistant paints for steel based on the epoxy resin and ammonium polyphosphate/pentaerythritol/melamine (APP/PER/MEL) system. The preliminary scanning electron microscope (SEM) analysis showed that halloysite modified with sulfuric acid (M2) has the best surface expansion. Nanotubes increased their volume and nanoplates were more delaminated. Temperature tests of the fire-resistant paints and subsequent SEM analysis confirmed these results, as a homogeneous structure with 50-fold multiplication was obtained for the sample with modified halloysite M2/expandable graphite, while the sample with pure halloysite/expandable graphite multiplied only 15-fold. Thermogravimetry/ differential scanning calorimetry (TG/DSC) analysis showed that the modified halloysite can significantly change the course of thermograms, even at low addition (7 wt%), and the mass loss can be reduced by up to about 13 wt%. The obtained results showed that the modified halloysite can successfully cooperate with expandable graphite and can be introduced into the intumescent system without deteriorating the physicochemical properties of the coating.

Influence of Synthetic Conditions on the Crystal Structure, Optical and Magnetic Properties of o-EuFeO3 Nanoparticles

In this paper, powders consisting of o-EuFeO3 nanoparticles were obtained by the co-precipitation method using two different precipitating agents (NH3 and (NH4)2CO3 solutions; corresponding products were denoted as samples S.1 and S.2, respectively) and followed by annealing for 1 h at 750, 850, and 950 °C. The magnetic, optical, and physicochemical characteristics of S.1 and S.2 were evaluated by means of EDXS (energy dispersive X-ray spectroscopy), PXRD (powder X-ray diffraction), TG/DSC (thermogravimetry/differential scanning calorimetry), FTIR (Fourier-transform infrared spectroscopy), TEM (transmission electron microscopy), UV-Vis DRS (Ultraviolet–Visible diffuse reflectance spectroscopy), and VSM (vibrating-sample magnetometry). The o-EuFeO3 structure was shown to be stable at annealed temperatures, and t = 850 °C is recommended for synthesizing such substances. The average size of o-EuFeO3 crystals is around 27 (S.1) and 34 nm (S.2). The results revealed a homogeneous distribution of the main elements on the samples’ surfaces, with morphology consisting of isometric and highly agglomerated nanoparticles. The bandgap value (Eg) of the synthesized samples was 2.31 (S.1) and 2.39 eV (S.2). Besides, these nanoparticles appeared to possess paramagnetic behavior.

Comparative Study of Experiments and Calculations on the Guest Molecules’ Escaping Mechanism of CL-20-Based Host–Guest Energetic Materials

CL-20-based host–guest energetic materials have high application value in the field of energetic materials. The phase-transition inhibition and stabilization mechanisms of CL-20-based host–guest energetic materials were revealed by combining experiments with molecular dynamics (MD) simulation. Based on the crystal structures, the super-cell models of host–guest energetic materials including CL-20/H2O, CL-20/H2O2, CL-20/N2O, and CL-20/CO2 were constructed. The phase transformation behavior and stability sequence of CL-20-based host–guest energetic materials were investigated using MD integrated with in situ powder X-ray diffraction (PXRD) and differential scanning calorimetry-thermogravimetry (DSC-TG) experiments. The escaping abilities of guest molecules from (002), (020), (021), (102), and (111) crystal faces of CL-20/H2O, CL-20/H2O2, CL-20/N2O, and CL-20/CO2 were evaluated using the target-MD method. It is proposed that the guest molecules could escape from the (002) crystal face more easily than the other faces. The escaping behaviors were studied using MD simulations. Based on the analysis of mean-square displacement (MSD), diffusion coefficients, and binding energies at different temperatures, the thermal stability order of the four CL-20-based host–guest materials was CL-20/CO2 > CL-20/N2O > CL-20/H2O2 > CL-20/H2O. This is consistent with experimental observations by in situ XRD and DSC analyses on these host–guest energetic materials. Meanwhile, by studying the escape paths of guest molecules, it was concluded that the escape method of guest molecules from a CL-20 crystal cell is “jumping” diffusion. By studying the MSD of host molecule CL-20 and the radial distribution function between the host molecule and the guest molecule, the structural stabilization mechanism of host–guest energetic materials was revealed. Our findings will help to reveal the solid-phase-transition inhibition mechanism of host–guest energetic materials and promote the development of host–guest explosives as smart materials.

Use of coal-fired slag in filling bodies with early strength for mining applications

The global output of coal-fired slag (CS) has far exceeded 300 million tons, and the annual output in China is 4.5 billion tons, which seriously affects the ecological security. Additionally, with the continuous increases in mine production capacities, the filling cost continues to rise, which seriously affects the normal production levels of the mines. To reduce the filling cost and make full use of the CS, this study was designed to realize diversified application of coal-fired slag (CS) as a backfill with early strength. First, physical and chemical analyses were conducted for coal-fired slag powder (CSP), fly ash (FA), flue gas desulfurization gypsum (FGDG) and mine waste rock (MWR). Based on the alkali excitation theory, mixture design, response surface theory and early strength testing of the backfill, the optimal ratio for the solid waste cementitious material and the backfill with early strength was determined. The primary and interaction effects of the backfill were analysed. Finally, the hydration mechanism for the CS-based cementing materials was revealed by monitoring the resistivity and water content and with scanning election microscopy (SEM), X-ray diffraction (XRD) and thermogravimetry/differential scanning calorimetry (TG-DSC) analyses of the hydration products. The results showed that (1) the total amount of SiO2 and Al2O3 in the CS was 61.08%, and the content of CaO was 17.3%, which indicated potential gelling activity. (2) The backfill with early strength was prepared by mixing CSP, FGDG and FA at 70%, 3% and 27%, with MWR and CS exhibiting a specific mass fraction (81%), binder-sand ratio (4:6) and CS-MWR ratio (5:5). The 3 d and 7 d uniaxial compressive strengths of the backfill were 1.7 MPa and 3 MPa. (3) The CS-MWR ratio of the backfill and the interaction between the CS-MWR ratio and binder-sand ratio significantly influenced on the early uniaxial compressive strength. (4) The early hydration process for the CS-based cementitious materials included the dissolution period, the induced formation and induction period and the condensation and hardening period. At 3 d, the hydration products were mainly generated by the CSP (the total amount of hydration products produced was 7.01%), while at 4 d–7 d, the FA was involved (the total amount of hydration products produced was 7.37%. The results of this research provide theoretical guidance for using CS to develop low-cost backfills with early strengths for application in mines.

Using polyvinylidene fluoride to improve ignition and combustion of micron-sized boron powder by fluorination reaction

Boron has a promising application in the field of propellants due to its high calorific value. However, the difficulty of ignition and the poor combustion efficiency of boron (B) have severely limited its efficient application. In response to this issue, this paper proposes to improve the ignition and combustion performance of micron-sized boron by the Polyvinylidene Fluoride (PVDF) coating. The effect of PVDF content on the B combustion performance was systematically studied using a Thermogravimetry-Differential Scanning Calorimetry (TG-DSC), a Transmission Electron Microscope (TEM), an X-Ray Diffractometer (XRD), a laser Particle Size Analyzer (PSA), and a high-speed camera. The results show that PVDF can significantly reduce the initial oxidation temperature of B powder and increase its reaction heat. When the PVDF content is 23wt%, the reaction heat and the combustion intensity of B powder reach the maximum and are significantly higher than those of the uncoated B powder. Moreover, the fluorination reaction that occurs during the combustion process not only can effectively shorten the combustion time of B powder, but also has a positive effect on its flame intensity and propagation speed, and it significantly reduces B particle agglomeration, which improves the combustion efficiency significantly. This study lays the foundation for the application of PVDF modified B in B-based solid propellants.

Preparation, stability, and molecular modeling of nitro-oleic acid/cyclodextrin complexes under aqueous conditions

Nitro-oleic acid (NO2-OA) is an endogenously produced pleiotropic modulator involved in cell redox homeostasis. The intrinsic property of NO2-OA is a decay reaction under aqueous conditions. This aqueous instability is simultaneously a problematic issue for NO2-OA sample handling and NO2-OA application in general. In this work NO2-OA (eq. mol. 9/10-NO2 isomers) was encapsulated with β-cyclodextrin (β-CD). The formation of the β-CD/NO2-OA complex was determined based on 1H NMR. The QM calculations revealed that dispersion forces are crucial for the stability of the complex. Based on thermogravimetry–differential scanning calorimetry, free NO2-OA was less thermally stable than its inclusion β-CD complex. The electrochemical reduction of the nitro group was investigated to determine the degradation kinetics of β-CD/NO2-OA. Under aqueous conditions, β-CD/NO2-OA degrades at a similar rate to NO2-OA alone. However, when β-CD/NO2-OA is stored in solid (lyophilized) form, no degradation was observed for a one-month period.

An insight into the thermal properties of struvite-k by Rietveld refinement method

This work investigated the thermal properties of struvite-k (a main binding phase and a strength-giving mineral from the magnesium potassium phosphate cements) exposed to different conditions by Rietveld Refinement Method coupled with X-ray diffraction analysis (XRD) identification, thermogravimetry/differential scanning calorimetry (TG/DSC) and Fourier-transform infrared spectroscopy (FTIR) method. The struvite-k presented significant vulnerability when exposed to above 70 °C, and destabilized to MgKPO4⋅H2O instead of MgKPO4, where, the remaining (0 3 1) and (2 1 2) planes were attributed to magnesium potassium phosphate monohydrate (MgKPO4·H2O). Coordinate a and c of the struvite-k crystal demonstrated significant responses to the heating temperature in comparison with coordinate b. Increasing the temperature up to 90 °C could decrease the length c of the struvite-k from 11.1022 Å to 9.8493 Å, and decrease its crystal size from 119.9 nm to 6.7 nm. The present work could provide fundamental knowledge on practical applications of MKPCs, such as construction, nuclear waste management, and phosphate recovery.

Superior catalytic effect of titania - porous carbon composite for the storage of hydrogen in MgH2 and lithium in a Li ion battery

A novel nanocomposite (0.2TiO2 + AC) with two promising applications is demonstrated, (i) as an additive for promoting hydrogen storage in magnesium hydride, (ii) as an active electrode material for hosting lithium in Li ion batteries (surface area of activated carbon (AC): 491 m2/g, pore volume: 0.252 cc/g, size of TiO2 particles: 20–30 nm). Transmission electron microscopy study provides evidence that well dispersed TiO2 nanoparticles are enclosed by amorphous carbon nets. A thermogravimetry-differential scanning calorimetry (TG-DSC) study proves that the nanocomposite is thermally stable up to ∼400 °C. Volumetric hydrogen storage tests and DSC studies further prove that a 3 wt% of 0.2TiO2+AC nanocomposite as additive not only lowers the dehydrogenation temperature of MgH2 over 100 °C but also maintains the performance consistency. Moreover, as a working electrode for Li ion battery, 0.2TiO2+AC offers a reversible capacity of 400 mAh/g at the charge/discharge rate of 0.1C and consistent stability up to 43 cycles with the capacity retention of 160 mAh/g at 0.4C. Such cost effective-high performance materials with applications in two promising areas of energy storage are highly desired for progressing towards sustainable energy development.

Comparative analysis of the explosion characteristics of magnesium dust and magnesium-aluminium alloy dust with two concentrations

ABSTRACT Magnesium (Mg) dust and magnesium–aluminum (Mg–Al) alloy dust are commonly produced and form a dust cloud in industrial manufacturing processes, which considerably increases explosion risk. This study examined three metal dusts: Mg, 48 mass% Mg–Al alloy, and 91 mass% Mg–Al alloy. A 20-L spherical explosion device was used to investigate the effect of different Mg concentrations. The results revealed that for all the samples, the explosion pressure (P ex) first increased and then decreased for a dust cloud concentration of 100–1000 g/m3. With the increase of dust particle size, the P ex of samples decreased. With the increase of ignition delay time, the P ex of samples first increased and then decreased, reaching the peak at 60 ms. Under identical conditions, when Mg concentration increased, the alloys became less stable. Thermogravimetry-differential scanning calorimetry findings revealed that the oxidation process of samples could be divided into three stages. The initial oxidation temperature of the alloys was lower than that of the pure Mg; however, in its primary oxidation stage, the mass gain rate of the Mg dust was more rapid than that of the Mg–Al alloys. In the oxidation of the alloys, elemental Mg reacted with oxygen first.

Regeneration of raw materials for aluminum electrolysis from spent carbon anodes via a closed-loop environmentally-friendly process based on aluminum–fluorine complexation

Spent carbon anode (SCA) discharged from the aluminum electrolysis industry is an unavoidable solid waste with an estimated production of 700 kilotons in 2021, which has been widely identified as the hazardous solid waste. A new two-stage leaching scheme comprising an aluminum salt leaching and an alkali leaching has been investigated in this study, by which valuable elements have been extracted from SCA. Effect of reaction conditions on the first-stage aluminum salt leaching process was investigated in detail. Under the optimal leaching conditions, the leaching rates of F, Na, and Al reached 98.00%, 94.94%, and 93.94%, respectively, and the recovered carbon purity was 85.84%. The fluorine recovery route was followed by the preparation of aluminum hydroxyfluoride precursor, namely Al2F3.24(OH)2.76 1.65H2O, through the mixing of two filtrates. Then thermogravimetry-differential scanning calorimetry (TG-DSC) curves were used to explore its calcination temperature point in detail. The final product was obtained as a mixture of AlF3 and Al2O3 with 95.94% purity. The characterization results showed that the calcined product was very similar to the commercial aluminum fluoride. Finally, the neutralized filtrate will be prepared by freezing and crystallizing Na2SO4, and the crystallized solution will be returned to the aluminum salt leaching process for recycling, which is the promise of green, recyclable, and high-value technology for realizing the detoxification of SCA and its subsequent utilization.

Crystal Structure, Raman, FTIR, UV-Vis Absorption, Photoluminescence Spectroscopy, TG-DSC and Dielectric Properties of New Semiorganic Crystals of 2-Methylbenzimidazolium Perchlorate.

Single crystals of 2-methylbenzimidazolium perchlorate were prepared for the first time with a slow evaporation method from an aqueous solution of a mixture of 2-methylbenzimidazole (MBI) crystals and perchloric acid HClO4. The crystal structure was determined by single crystal X-ray diffraction (XRD) and confirmed by XRD of powder. Angle-resolved polarized Raman and Fourier-transform infrared (FTIR) absorption spectra of crystals consist of lines caused by molecular vibrations in MBI molecule and ClO4- tetrahedron in the region ν = 200-3500 cm-1 and lattice vibrations in the region of 0-200 cm-1. Both XRD and Raman spectroscopy show a protonation of MBI molecule in the crystal. An analysis of ultraviolet-visible (UV-Vis) absorption spectra gives an estimation of an optical gap Eg~3.9 eV in the crystals studied. Photoluminescence spectra of MBI-perchlorate crystals consist of a number of overlapping bands with the main maximum at Ephoton ≅ 2.0 eV. Thermogravimetry-differential scanning calorimetry (TG-DSC) revealed the presence of two first-order phase transitions with different temperature hysteresis at temperatures above room temperature. The higher temperature transition corresponds to the melting temperature. Both phase transitions are accompanied by a strong increase in the permittivity and conductivity, especially during melting, which is similar to the effect of an ionic liquid.

Effect of Al–Li Alloy on the Combustion Performance of AP/RDX/Al/HTPB Propellant

Aluminium–lithium alloy (Al–Li alloy) powder has excellent ignition and combustion performance. The combustion product of Al–Li alloy powder combined with ammonium perchlorate is gaseous at the working temperature of solid rocket motors, which greatly reduces the loss of two-phase flow. Experimental investigations were thoroughly conducted to determine the effect of the Al–2.5Li (2.5 wt% lithium) content on propellant combustion and agglomeration based on thermogravimetry-differential scanning calorimetry, heat combustion, laser ignition, combustion diagnosis, a simulated 75 mm solid rocket motor and a condensed combustion products (CCPs) collection device. The results show that the exothermic heat and weight gain upon the thermal oxidation of Al–Li alloy is obviously higher than those of Al powder. Compared with the reference propellant’s formulation, Al–2.5Li leads to an increase in the burning rate and a decrease in the size of the condensed combustion products of the propellants. As the Al–2.5Li alloy content gradually increases from 0 wt% to 19 wt%, the burning rate increases from 5.391 ± 0.021 mm/s to 7.244 ± 0.052 mm/s at 7 MPa of pressure; meanwhile, the pressure exponent of the burning rate law is changed from 0.326 ± 0.047 to 0.483 ± 0.045, and the d43 of the combustion residue is reduced from 165.31 ± 36.18 μm to 12.95 ± 4.00 μm. Compared to the reference propellant’s formulation, the combustion efficiency of the HTPB propellant is increased by about 4.4% when the Al–2.5Li alloy content is increased from 0 to 19%. Therefore, Al–2.5Li alloy powder is a promising fuel for solid propellants.

TG-DSC and TG-FTIR Studies of Annelated Triazinylacetic Acid Ethyl Esters-Potential Anticancer Agents.

To avoid problems associated with the storage and processing of newly developed potential medicines, there is a need to carry out thermal studies in the preclinical phase of drug development. The thermal behaviour and decomposition pathway of a whole novel class of patented potential molecular pharmaceutics, i.e., ethyl 2-[4-oxo-8-(R-phenyl)-4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-3-yl]acetates (1-6) were reported for the first time in inert and oxidative atmospheres. The experiments were conducted with the use of simultaneous thermogravimetry/differential scanning calorimetry (TG-DSC) and simultaneous thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR). The decomposition pathways of compounds 1-6 were found to be different under oxidative and inert conditions. It was proven that the investigated molecules reveal higher thermal stability under a synthetic air atmosphere than under a nitrogen atmosphere, and their decomposition is preceded by the melting process. Among all the investigated compounds, only the meta-chloro derivative (4) was found to exhibit interesting polymorphic behaviour at a low heating rate (10 °C min-1). It was proven that the oxidative decomposition process of the studied molecules proceeds in three overlapping stages accompanied by strong exothermic effects. Additionally, it was concluded that the title compounds were stable up to a temperature of 195-216 °C in an atmosphere of synthetic air, and their thermal stability decreased in the order of R at the benzene ring: 4-CH3 > 3,4-Cl2 > 4-Cl > H > 2-OCH3 > 3-Cl.

Evolution behaviour of the lattice and thermal expansion of a high-entropy fluorite oxide (Zr0.2Ce0.2Hf0.2Y0.2Al0.2)O2-δ during heating and cooling in an inert atmosphere

High-entropy fluorite oxides (HEFOs) exhibit improved performance as promising thermal barrier coatings (TBCs). A proper thermal expansion coefficient (TEC) is required owing to the direct contact of TBCs with metal substrates. Herein, we study the evolution behaviour of the lattice and thermal expansion of a HEFO (Zr0.2Ce0.2Hf0.2Y0.2Al0.2)O2-δ during heating and cooling in an inert atmosphere. The HEFO was characterised as follows: (1) X-ray photoelectron spectroscopy to determine the valence states of the chemical elements, (2) X-ray diffraction to examine the crystal phase and calculate the TECs, and (3) thermogravimetry-differential scanning calorimetry to probe the temperature ranges of the reduction reactions. Results show that as the temperature increased from 300 to 800 °C, the nominal composition changed from (Zr0.2Hf0.2Ce0.2Y0.2Al0.2)O1.765 to (Zr0.2Hf0.2Ce0.2Y0.2Al0.2)O1.711, because of the partial valence reduction of Ce4+, Zr4+, and Hf 4+. Furthermore, 44.59% of Ce, 20.28% of Zr, and 23.93% of Hf presented +3 valence at 800 °C. Valence reduction occurred only during heating. Although suboxide cations were present, (Zr0.2Ce0.2Hf0.2Y0.2Al0.2)O2-δ maintained a high-entropy fluorite crystal structure. The TEC increased from 9.38 to 13.12 × 10−6 K−1 during heating and decreased from 10.71 to 9.15 × 10−6 K−1 during cooling. These results reveal the evolutionary trends of defective fluorite-type high-entropy oxide compositions with reduction reactions at elevated temperatures. This provides a new perspective on the relationship between the lattice, TEC, and chemical composition.

Exploration of the bioenergy potential of Dactyloctenium aegyptium through pyrolysis, kinetics, and thermodynamic parameters to produce clean fuels and biochemicals

The Egyptian grass (Dactyloctenium aegyptium) is a common low-cost coarse grass which is adapted to poor soils. The biomass of the Egyptian grass may be used to produce cleaner and sustainable fuels through pyrolysis without causing any contradictory impact on the land for food. It is profound to understand the thermochemical character of the Egyptian grass biomass for its efficient thermal conversion to clean fuels and chemicals. The current study elucidated the pyrolysis process of this biomass for the very first time based on the pyrolysis data. Heat-dried powdered biomass of Dactyloctenium aegyptium was pyrolyzed at 10 min−1, 30 min−1 and 50 °C min−1 in a simultaneous Thermogravimetry–Differential Scanning Calorimetry analyzer (TGA-DSC) under nitrogen atmosphere. Isoconversional models of Kissenger-Akahira-Sunose (KSA), Flynn–Wall–Ozawa (FWO) and first and second order reaction kinetics model were used to analyze the pyrolytic kinetic parameters. The pyrolysis of D. aegyptium grass biomass was shown to be a three-stage pyrolysis process where around 50 % of the product formation was happening within a narrow temperature range of 240–360 °C with the Activation energies ranged from 167 to 267 kJ mol−1 and thermodynamic parameters including 18.25–18.63 MJ kg−1 of high heating values, 169–177 kJ mol−1 of Gibb’s free energies, and 166–256 kJ mol−1 of reaction enthalpy have shown the outstanding pyrolysis and co-pyrolysis potential of Egyptian grass to produce clean fuels.

Pyrolysis synthesis of CuWO4@C composite catalysts as Pt-free counter electrode for dye-sensitized solar cells

Transition metal compound catalysts have potential applications in Pt-free counter electrode (CE), which are one of the important strategies for reducing costs and improving power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs). Herein, CuWO4@C composite catalysts were synthesized by pyrolyzing Cu-based polyoxotungstate (H3PW12O40) precursor in presence of polyaniline. The effect of pyrolysis temperature (600, 700, 800, 900, 1000 and 1100 ℃) on the compositions, morphologies and structures of CuWO4@C composite was investigated by Thermogravimetry-Derivative thermogravimetry-Differential scanning calorimetry (TG-DTG-DSC) simultaneous, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM) and N2 adsorption-desorption analysis. The photovoltaic properties of different CuWO4@C composites CEs were determined by photocurrent-photovoltage (J-V) measurement. The results reveal that the pyrolysis at 800 ℃ was optimum to get the best CuWO4@C composite CE, which yielded the highest PCE of 7.11% for the regeneration of I3−/I− couple in the DSSCs. The structure-activity relationship of the CuWO4@C composite catalysts was discussed.

Sintering Properties of Tetragonal Zirconia Nanopowder Preparation of the NaCl + KCl Binary System by the Sol–Gel–Flux Method

Tetragonal zirconia nanopowders (3Y-TZP NPs) stabilized by 3 mol % Y2O3 were synthesized by a novel sol–gel–flux method. The effects of calcination temperature, Y2O3 content, and molten salt system (NaCl + KCl binary system and NaCl unary system) on the phase composition and morphology of nanopowders (NPs) were investigated. Meanwhile, the sintering properties of the prepared 3Y-TZP NPs were studied. The 3Y-TZP NPs and sintered ceramics were characterized by thermogravimetry-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) analysis, and X-ray fluorescence (XRF) spectroscopy. The results show that the optimum calcination temperature for obtaining dispersed ZrO2 NPs is reduced from 800 to 660 °C when the NaCl unary system is substituted by the NaCl + KCl binary system. 3Y-TZP NPs with a single tetragonal phase are obtained in the NaCl + KCl binary system when Y2O3 content in the raw material is 5 mol %. The average particle size of the obtained ZrO2 NPs is reduced from 47.25 nm in the unary system to 26.18 nm in the binary system because of the lower calcining temperature. Furthermore, the 3Y-TZP NPs obtained in the binary system have narrower particle size distribution and better sintering performance than ZrO2 NPs obtained in the unary system. After sintering for 4 h at 1200 °C, the former generated 3Y-TZP ceramics with higher density and finer grain size. This work produced narrow-distributed well-dispersed 3Y-TZP NPs with quasi-spherical morphology, which are good candidates for the applications, including oxygen sensors and thermal barrier coatings.

Hepatoprotective Pyrazinamide–Baicalein Cocrystal with a Rare Ratio of 7:3

Exploring solid forms with low toxicity and high safety is a universal theme in drug research. This study developed a new cocrystal to optimize the severe hepatotoxicity of the first-line antituberculosis drug pyrazinamide (PZA). Baicalein (BCL) was chosen as the cocrystal former for its powerful hepatoprotective effect. The PZA–BCL cocrystal was structurally characterized by single-crystal X-ray diffraction (SCXRD), powder XRD (PXRD), differential scanning calorimetry–thermogravimetry (DSC-TG), and infrared (IR) spectroscopy. Meanwhile, the in vitro dissolution and in vivo pharmacokinetics and hepatotoxicity of the cocrystal were evaluated systematically. The results highlight that the BCL obtained tremendous improvements in water solubility, bioavailability, and hepatoprotective effect after cocrystal formation, hence almost removing the toxicity of PZA finally. Furthermore, it is worth noting that the molar ratio of 7:3 was first observed in the cocrystal, which is rare relative to the widely reported simple integer ratio of pharmaceutical cocrystals. The present research provides an interesting case for applying cocrystal technology in the field of drug safety.

Thermal studies of novel heat-resistant 3,6-dinitropyrazolo[4,3-c]pyrazole-based energetic materials

1,4-Bis(2′,4′,6′-trinitrophenyl)−3,6-dinitro[4,3-c]pyrazole (DTNBDNP) is a newly developed heat-resistant explosive exhibiting superior properties to most traditional heat-resistant energetic materials with a significantly high thermal decomposition temperature of 410 °C. Detailed thermal behaviors and nonisothermal decomposition kinetics of DTNBDNP and 1,4-bis(2′,4′-dinitrophenyl)−3,6-dinitro[4,3-c]pyrazole (DDNBDNP) were investigated using a differential scanning calorimeter (DSC), and the thermal safety was evaluated by different criteria, including the self-accelerating decomposition temperature and critical temperature of thermal explosion. Their thermodynamic functions were also obtained based on the specific heat capacity data determined using a micro-DSC method. Further studies on the thermal decomposition mechanism were carried out through condensed-phase thermolysis/Fourier transform infrared (in situ FTIR) spectroscopy and the combination of differential scanning calorimetry–thermogravimetry–mass spectrometry–Fourier transform infrared spectroscopy (DSC–TG–MS–FTIR) techniques. The experimental results prove that the decomposition of DTNBDNP and DDNBDNP is most likely to begin with a ring-opening reaction of the fused-heterocycle backbone. In addition, the main gaseous products, including NO, CO2, N2O, and NO2, are released from the decomposition of DTNBDNP and DDNBDNP.