Johnson–Cook Parameter Identification for Commercially Pure Titanium at Room Temperature under Quasi-Static Strain Rates

Background: To simulate mechanical shocks on an intracranial implant called WIMAGINE^®, Clinatec chose a Johnson–Cook model to account for the viscoplastic behavior of grade 2 titanium in a dynamic study using Radioss^©. Methods: Thirty tensile specimens were subjected to tensile tests at room temperature, and the influence of the strain rate (8 × 10⁻³ and 8 × 10⁻² s⁻¹) and sandblasting was analyzed. Relaxations were included in the tests to analyze viscosity phenomena. Results: A whole set of parameters was identified for the elastic and plastic parts. Strain rate influence on stress was negligible at these strain rates. As expected, the sandblasting hardened the material during the tests by decreasing the hardening parameters, while local necking occurred at an earlier strain. Conclusions: This article provides the parameters of a Johnson–Cook model to simulate the elastoplastic behavior of pure titanium (T40, grade 2) in Finite Element Model (FEM) software.     

Fe–Doped TiO2–Carbonized Medium–Density Fiberboard for Photodegradation of Methylene Blue under Visible Light

Fe–doped titanium dioxide–carbonized medium–density fiberboard (Fe/TiO₂–cMDF) was evaluated for the photodegradation of methylene blue (MB) under a Blue (450 nm) light emitting diode (LED) module (6 W) and commercial LED (450 nm + 570 nm) bulbs (8 W, 12 W). Adsorption under daylight/dark conditions (three cycles each) and photodegradation (five cycles) were separately conducted. Photodegradation under Blue LED followed pseudo-second-order kinetics while photodegradation under commercial LED bulbs followed pseudo-first-order kinetics. Photodegradation rate constants were corrected by subtracting the adsorption rate constant except on the Blue LED experiment due to their difference in kinetics. For 8 W LED, the rate constants remained consistent at ~11.0 × 10⁻³/h. For 12 W LED, the rate constant for the first cycle was found to have the fastest photodegradation performance at 41.4 × 10⁻³/h. After the first cycle, the rate constants for the second to fifth cycle remained consistent at ~28.5 × 10⁻³/h. The energy supplied by Blue LED or commercial LEDs was sufficient for the bandgap energy requirement of Fe/TiO₂–cMDF at 2.60 eV. Consequently, Fe/TiO₂–cMDF was considered as a potential wood-based composite for the continuous treatment of dye wastewater under visible light.     

Copper Film Modified Glassy Carbon Electrode and Copper Film with Carbon Nanotubes Modified Screen-Printed Electrode for the Cd(II) Determination

A copper film modified glassy carbon electrode (CuF/GCE) and a novel copper film with carbon nanotubes modified screen-printed electrode (CuF/CN/SPE) for anodic stripping voltammetric measurement of ultratrace levels of Cd(II) are presented. During the development of the research procedure, several main parameters were investigated and optimized. The optimal electroanalytical performance of the working electrodes was achieved in electrolyte 0.1 M HCl and 2 × 10⁻⁴ M Cu(II). The copper film modified glassy carbon electrode exhibited operation in the presence of dissolved oxygen with a calculated limit of detection of 1.7 × 10⁻¹⁰ M and 210 s accumulation time, repeatability with RSD of 4.2% (n = 5). In the case of copper film with carbon nanotubes modified screen-printed electrode limit of detection amounted 1.3 × 10⁻¹⁰ M for accumulation time of 210 s and with RSD of 4.5% (n = 5). The calibration curve has a linear range in the tested concentration of 5 × 10⁻¹⁰–5 × 10⁻⁷ M (r = 0.999) for CuF/GCE and 3 × 10⁻¹⁰–3 × 10⁻⁷ M (r = 0.999) for CuF/CN/SPE with 210 s accumulation time in both cases. The used electrodes enable trace determination of cadmium in different environmental water samples containing organic matrix. The validation of the proposed procedures was carried out through analysis certified reference materials: TM-25.5, SPS-SW1, and SPS-WW1.     

Fickian-Based Empirical Approach for Diffusivity Determination in Hollow Alginate-Based Microfibers Using 2D Fluorescence Microscopy and Comparison with Theoretical Predictions

Hollow alginate microfibers (od = 1.3 mm, id = 0.9 mm, th = 400 µm, L = 3.5 cm) comprised of 2% (w/v) medium molecular weight alginate cross-linked with 0.9 M CaCl₂ were fabricated to model outward diffusion capture by 2D fluorescent microscopy. A two-fold comparison of diffusivity determination based on real-time diffusion of Fluorescein isothiocyanate molecular weight (FITC MW) markers was conducted using a proposed Fickian-based approach in conjunction with a previously established numerical model developed based on spectrophotometric data. Computed empirical/numerical (D_empiricial/D_numerical) diffusivities characterized by small standard deviations for the 4-, 70- and 500-kDa markers expressed in m²/s are (1.06 × 10⁻⁹ ± 1.96 × 10⁻¹⁰)/(2.03 × 10⁻¹¹), (5.89 × 10⁻¹¹ ± 2.83 × 10⁻¹²)/(4.6 × 10⁻¹²) and (4.89 × 10⁻¹² ± 3.94 × 10⁻¹³)/(1.27 × 10⁻¹²), respectively, with the discrimination between the computation techniques narrowing down as a function of MW. The use of the numerical approach is recommended for fluorescence-based measurements as the standard computational method for effective diffusivity determination until capture rates (minimum 12 fps for the 4-kDa marker) and the use of linear instead of polynomial interpolating functions to model temporal intensity gradients have been proven to minimize the extent of systematic errors associated with the proposed empirical method.     

Rapid Detection of Listeria by Bacteriophage Amplification and SERS-Lateral Flow Immunochromatography

A rapid Listeria detection method was developed utilizing A511 bacteriophage amplification combined with surface-enhanced Raman spectroscopy (SERS) and lateral flow immunochromatography (LFI). Anti-A511 antibodies were covalently linked to SERS nanoparticles and printed onto nitrocellulose membranes. Antibody-conjugated SERS nanoparticles were used as quantifiable reporters. In the presence of A511, phage-SERS nanoparticle complexes were arrested and concentrated as a visible test line, which was interrogated quantitatively by Raman spectroscopy. An increase in SERS intensity correlated to an increase in captured phage-reporter complexes. SERS limit of detection was 6 × 10⁶ pfu·mL⁻¹, offering detection below that obtainable by the naked eye (LOD 6 × 10⁷ pfu·mL⁻¹). Phage amplification experiments were carried out at a multiplicity of infection (MOI) of 0.1 with 4 different starting phage concentrations monitored over time using SERS-LFI and validated by spot titer assay. Detection of L. monocytogenes concentrations of 1 × 10⁷ colony forming units (cfu)·mL⁻¹, 5 × 10⁶ cfu·mL⁻¹, 5 × 10⁵ cfu·mL⁻¹ and 5 × 10⁴ cfu·mL⁻¹ was achieved in 2, 2, 6, and 8 h, respectively. Similar experiments were conducted at a constant starting phage concentration (5 × 10⁵ pfu·mL⁻¹) with MOIs of 1, 2.5, and 5 and were detected in 2, 4, and 5 h, respectively.     

Prednisolone inhibits phagocytosis by polymorphonuclear leucocytes via steroid receptor mediated events

Prednisolone, at concentrations between 2·78 × 10⁻⁶ M (1 μg/ml) and 1·39 × 10⁻⁸ M (5 × 10⁻³ μg/ml) exerts an inhibitory effect on the phagocytosis of latex particles by normal human polymorphonuclear leucocytes in vitro as assessed by electron microscopical analysis. This inhibition appears to be receptor-mediated, as it is dependent upon RNA and protein synthesis and is glucocorticoid specific.     

Electrochemically Activated Screen-Printed Carbon Sensor Modified with Anionic Surfactant (aSPCE/SDS) for Simultaneous Determination of Paracetamol,Diclofenac and Tramadol

In this work, an electrochemically activated screen-printed carbon electrode modified with sodium dodecyl sulfate (aSPCE/SDS) was proposed for the simultaneous determination of paracetamol (PA), diclofenac (DF), and tramadol (TR). Changes of surface morphology and electrochemical behaviour of the electrode after the electrochemical activation with H₂O₂ and SDS surface modification were studied by scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The influence of various parameters on the responses of the aSPCE/SDS such as pH and concentration of the buffer, SDS concentration, and techniques parameters were investigated. Using optimised conditions (E_acc. of −0.4 V, t_acc. of 120 s, ΔE_A of 150 mV, ν of 250 mV s⁻¹, and t_m of 10 ms), the aSPCE/SDS showed a good linear response in the concentration ranges of 5.0 × 10⁻⁸–2.0 × 10⁻⁵ for PA, 1.0 × 10⁻⁹–2.0 × 10⁻⁷ for DF, and 1.0 × 10⁻⁸–2.0 × 10⁻⁷ and 2.0 × 10⁻⁷–2.0 × 10⁻⁶ mol L⁻¹ for TR. The limits of detection obtained during the simultaneous determination of PA, DF, and TR are 1.49 × 10⁻⁸ mol L⁻¹, 2.10 × 10⁻¹⁰ mol L⁻¹, and 1.71 × 10⁻⁹ mol L⁻¹, respectively. The selectivity of the aSPCE/SDS was evaluated by examination of the impact of some inorganic and organic substances that are commonly present in environmental and biological samples on the responses of PA, DF, and TR. Finally, the differential pulse adsorptive stripping voltammetric (DPAdSV) procedure using the aSPCE/SDS was successfully applied for the determination of PA, DF, and TR in river water and serum samples as well as pharmaceuticals.     

Effects of non-steroidal anti-inflammatory drugs and prostaglandins on alkali secretion by rabbit gastric fundus in vitro

The effects of non-steroidal anti-inflammatory drugs and prostaglandins E₂ and F_2α on the secretory and electrical activity of isolated rabbit fundic mucosa have been studied. Spontaneous acid secretion was inhibited by serosal side application of sodium thiocyanate (6×10⁻²M) and the resulting alkali secretion measured by pH stat tiration. Serosal side application of indomethacin (10⁻⁵M) or aspirin (3×10⁻³M) inhibited alkali secretion (0·55±0·06 to 0·12±0·06 μmol/cm²/h, n=6, p<0·01 and 0·28±0·06 to 0·11±0·03 μmol/cm²/h, n=7, p<0·02 respectively). Mucosal or serosal side prostaglandin E₂ (10⁻⁵ to 10⁻¹⁰M) and F_2α (10⁻⁴ to 10⁻¹⁰M) failed to alter the rate of alkalinisation but secretion was significantly increased by serosal side 16,16-dimethyl-prostaglandin E₂ (10⁻⁶M) (0·90±0·20 to 1·50±0·30 μmol/cm²/h, n=6, p<0·01). Serosal side application of 10⁻⁶M prostaglandin E₂ to fundic mucosae pretreated with either aspirin (5×10⁻³M) or indomethacin (10⁻⁵M), to reduce endogenous E₂ formation, also failed to alter alkali secretion. Pretreatment of the mucosa with 16,16-dimethyl-E₂ (10⁻⁶M) abolished the inhibitory effect of indomethacin (10⁻⁵M) on alkali secretion (n=6) but did not modify the secretory response to aspirin (3×10⁻³M) (fall in alkali secretion with aspirin = 81±11% and with aspirin plus 16,16-dimethyl-E₂ = 72±10%, n=7). In the doses used, none of the prostaglandins or non-steroidal anti-inflammatory drugs altered transmucosal potential difference or electrical resistance. These results show that the damaging agents, aspirin and indomethacin, both inhibit gastric alkali secretion but that modes of action may differ. The observation that prostaglandins, E₂ and F_2α failed to increase alkali production suggests that their protective activity against a variety of damaging agents as shown by others, may be mediated by another mechanism.     

Substrate positioning controls the partition between halogenation and hydroxylation in the aliphatic halogenase,SyrB2

The α-ketoglutarate-dependent hydroxylases and halogenases employ similar reaction mechanisms involving hydrogen-abstracting Fe(IV)-oxo (ferryl) intermediates. In the halogenases, the carboxylate residue from the His₂(Asp/Glu)₁“facial triad” of iron ligands found in the hydroxylases is replaced by alanine, and a halide ion (X⁻) coordinates at the vacated site. Halogenation is thought to result from “rebound” of the halogen radical from the X-Fe(III)-OH intermediate produced by hydrogen (H^•) abstraction to the substrate radical. The alternative decay pathway for the X-Fe(III)-OH intermediate, rebound of the hydroxyl radical to the substrate radical (as occurs in the hydroxylases), reportedly does not compete. Here we show for the halogenase SyrB2 that positioning of the alkyl group of the substrate away from the oxo/hydroxo ligand and closer to the halogen ligand sacrifices H^•-abstraction proficiency for halogen-rebound selectivity. Upon replacement of l-Thr, the C4 amino acid tethered to the SyrB1 carrier protein in the native substrate, by the C5 amino acid l-norvaline, decay of the chloroferryl intermediate becomes 130× faster and the reaction outcome switches to primarily hydroxylation of C5, consistent with projection of the methyl group closer to the oxo/hydroxo by the longer side chain. Competing H^• abstraction from C4 results primarily in chlorination, as occurs at this site in the native substrate. Consequently, deuteration of C5, which slows attack at this site, switches both the regioselectivity from C5 to C4 and the chemoselectivity from hydroxylation to chlorination. Thus, substrate-intermediate disposition and the carboxylate → halide ligand swap combine to specify the halogenation outcome.     

A synthetic host-guest system achieves avidin-biotin affinity by overcoming enthalpy-entropy compensation

The molecular host cucurbit[7]uril forms an extremely stable inclusion complex with the dicationic ferrocene derivative bis(trimethylammoniomethyl)ferrocene in aqueous solution. The equilibrium association constant for this host-guest pair is 3 × 10¹⁵ M⁻¹ (K_d = 3 × 10⁻¹⁶ M), equivalent to that exhibited by the avidin–biotin pair. Although purely synthetic systems with larger association constants have been reported, the present one is unique because it does not rely on polyvalency. Instead, it achieves its extreme affinity by overcoming the compensatory enthalpy–entropy relationship usually observed in supramolecular complexes. Its disproportionately low entropic cost is traced to extensive host desolvation and to the rigidity of both the host and the guest.     

Terahertz Sensor via Ultralow-Loss Dispersion-Flattened Polymer Optical Fiber: Design and Analysis

A novel cyclic olefin copolymer (COC)-based polymer optical fiber (POF) with a rectangular porous core is designed for terahertz (THz) sensing by the finite element method. The numerical simulations showed an ultrahigh relative sensitivity of 89.73% of the x-polarization mode at a frequency of 1.2 THz and under optimum design conditions. In addition to this, they showed an ultralow confinement loss of 2.18 × 10⁻¹² cm⁻¹, a high birefringence of 1.91 × 10⁻³, a numerical aperture of 0.33, and an effective mode area of 1.65 × 10⁵ μm² was obtained for optimum design conditions. Moreover, the range dispersion variation was within 0.7 ± 0.41 ps/THz/cm, with the frequency range of 1.0–1.4 THz. Compared with the traditional sensor, the late-model sensor will have application value in THz sensing and communication.     

Microstructure and Wear Properties of Laser Cladding WC/Ni-Based Composite Layer on Al–Si Alloy

The microstructural and wear properties of laser-cladding WC/Ni-based layer on Al–Si alloy were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS) and wear-testing. The results show that, compared with the original specimen, the microhardness and wear resistance of the cladding layer on an Al–Si alloy were remarkably improved, wherein the microhardness of the layer achieved 1100 HV and the average friction coefficient of the layer was barely 0.14. The mainly contributor to such significant improvement was the generation of a WC/Ni-composite layer of Al–Si alloy during laser cladding. Two types of carbides, identified as M₇C₃ and M₂₃C₆, were found in the layer. The wear rate of the layer first increased and then decreased with the increase in load; when the load was 20 N, 60 N and 80 N, the wear rate of layer was1.89 × 10⁻³ mm³·m⁻¹, 3.73 × 10⁻³ mm³·m⁻¹ and 2.63 × 10⁻³ mm³·m⁻¹, respectively, and the average friction coefficient (0.14) was the smallest when the load was 60 N.     

Performance Improvement of PVDF–HFP-Based Gel Polymer Electrolyte with the Dopant of Octavinyl-Polyhedral Oligomeric Silsesquioxane

Gel polymer electrolytes have the advantages of both a solid electrolyte and a liquid electrolyte. As a transitional product before which a solid electrolyte can be comprehensively used, gel polymer electrolytes are of great research value. They can reduce the risk of spontaneous combustion and explosion caused by leakage during the use of conventional liquid electrolytes. Poly(vinylidene-fluoride-co-hexafluoropropylene) (PVDF–HFP), a material with excellent performance, has been widely utilized in the preparation of gel polymer electrolytes. Here, PVDF–HFP-based gel polymer membranes with polyvinyl pyrrolidone (PVP) pores were prepared using a phase inversion method, and Octavinyl-polyhedral oligomeric silsesquioxane (OVAPOSS) was doped to improve its temperature resistance as well as its ionic conductivity, to enhance its safety and electrochemical performance. The final prepared polymer membrane had a porosity of 85.06% and still had a certain mechanical strength at 160 °C without any shrinkage. The gel polymer electrolyte prepared with this polymer membrane had an ionic conductivity of 1.62 × 10⁻³ S·cm⁻¹ at 30 °C, as well as an electrochemical window of about 5.5 V. The LiCoO₂-Li button half-cell prepared therefrom had a specific capacity of 141 mAh·g⁻¹ at a rate of 1C. The coulombic efficiency remained above 99% within 100 cycles and the capacity retention rate reached 99.5%, which reveals an excellent cycling stability.     

Polyaniline Synthesized by Different Dopants for Fluorene Detection via Photoluminescence Spectroscopy

The effects of different dopants on the synthesis, optical, electrical and thermal features of polyaniline were investigated. Polyaniline (PANI) doped with p-toluene sulfonic acid (PANI-PTSA), camphor sulphonic acid (PANI-CSA), acetic acid (PANI-acetic acid) and hydrochloric acid (PANI-HCl) was synthesized through the oxidative chemical polymerization of aniline under acidic conditions at ambient temperature. Fourier transform infrared light, X-ray diffraction, UV-visible spectroscopy, field emission scanning electron microscopy, photoluminescence spectroscopy and electrical analysis were used to define physical and structural features, bandgap values, electrical conductivity and type and degree of doping, respectively. Tauc calculation reveals the optical band gaps of PANI-PTSA, PANI-CSA, PANI-acetic acid and PANI-HCl at 3.1, 3.5, 3.6 and 3.9 eV, respectively. With the increase in dopant size, crystallinity is reduced, and interchain separations and d-spacing are strengthened. The estimated conductivity values of PANI-PTSA, PANI-CSA, PANI-acetic acid and PANI-HCl are 3.84 × 10¹, 2.92 × 10¹, 2.50 × 10⁻², and 2.44 × 10⁻² S·cm⁻¹, respectively. Particularly, PANI-PTSA shows high PL intensity because of its orderly arranged benzenoid and quinoid units. Owing to its excellent synthesis, low bandgap, high photoluminescence intensity and high electrical features, PANI-PTSA is a suitable candidate to improve PANI properties and electron provider for fluorene-detecting sensors with a linear range of 0.001–10 μM and detection limit of 0.26 nM.     

Intestinal mucosal uptake of iron and iron retention in idiopathic haemochromatosis as evidence for a mucosal abnormality

The process of iron absorption has been studied in 23 patients with idiopathic haemochromatosis, in eight with iron-deficiency anaemia, and in 20 control subjects. The initial uptake of iron by the intestinal mucosa was estimated by administering ⁵⁹Fe-ferric citrate during a standard meal together with a non-absorbable marker, ⁵¹Cr-chromic chloride. Body iron absorption (iron retained at 14 days) was measured by whole body counting with discriminant analysis to separate the two isotopes. Thus, the fraction of the initial mucosal uptake finally retained in the body was calculated (the mucosal transport index of iron).In control subjects the mean values for mucosal uptake of iron and body iron absorption were 12·0 − SD 4·9% and 3·6 − SD 2·4%, with a mean mucosal transport index of 0·31 − SD 0·21. Mucosal iron uptake and body absorption were both considerably increased in the patients with iron-deficiency anaemia (33·5 − 15·6 and 29·8 − 17·0% respectively) and in the eight patients with idiopathic haemochromatosis treated by venesection therapy until the excess iron stores were removed (27·2 − 12·0 and 26·6 − 14·6% respectively). The mucosal transport index in all these subjects approached 1·0. Eight patients with haemochromatosis were studied before venesection therapy. The mucosal uptake of iron was within the normal range in all (mean 14·0 − 2·8%) but body iron absorption was increased in five (mean 9·1 − 4·8%). The mean mucosal transport index of iron was significantly increased in this group (0·62 − 0·28; p < 0·01).The findings suggest that the increased iron absorption in subjects with idiopathic haemochromatosis results from an abnormality of the intestinal mucosa and not from altered intraluminal factors. However, whether the aberrant mucosal cell function is a primary defect in the cell or an acquired change, dependent on humoral or corporeal factors, is unknown.     

Enhancement of Y5−xPrxSb3−yMy (M = Sn,Pb) Electrodes for Lithium- and Sodium-Ion Batteries by Structure Disordering and CNTs Additives

The maximally disordered (MD) phases with the general formula Y_5−xPr_xSb_3−yM_y (M = Sn, Pb) are formed with partial substitution of Y by Pr and Sb by Sn or Pb in the binary Y₅Sb₃ compound. During the electrochemical lithiation and sodiation, the formation of Y_5-xPr_xSb_3-yM_yLi_z and Y_5−xPr_xSb_3−yM_yNa_z maximally disordered–high entropy intermetallic phases (MD-HEIP), as the result of insertion of Li/Na into octahedral voids, were observed. Carbon nanotubes (CNT) are an effective additive to improve the cycle stability of the Y_5−xPr_xSb_3−yM_y (M = Sn, Pb) anodes for lithium-ion (LIBs) and sodium-ion batteries (SIBs). Modification of Y_5−xPr_xSb_3−ySn_y alloys by carbon nanotubes allowed us to significantly increase the discharge capacity of both types of batteries, which reaches 280 mAh · g⁻¹ (for LIBs) and 160 mAh · g⁻¹ (for SIBs), respectively. For Y_5−xPrxSb_3−yPb_y alloys in which antimony is replaced by lead, these capacities are slightly smaller and are 270 mAh · g⁻¹ (for LIBs) and 155 mAh · g⁻¹ (for SIBs), respectively. Results show that structure disordering and CNT additives could increase the electrode capacities up to 30% for LIBs and up to 25% for SIBs.     

Bismuth/Porous Graphene Heterostructures for Ultrasensitive Detection of Cd (II)

Heavy metals pollution is one of the key problems of environment protection. Electrochemical methods, particularly anodic stripping voltammetry, have been proven a powerful tool for rapid detection of heavy metal ions. In the present work, a bismuth modified porous graphene (Bi@PG) electrode as an electrochemical sensor was adopted for the detection of heavy metal Cd²⁺ in an aqueous solution. Combining excellent electronic properties in sensitivity, peak resolution, and high hydrogen over-potential of bi-continuous porous Bi with the large surface-area and high conductivity on PG, the Bi@PG electrode exhibited excellent sensing ability. The square wave anodic stripping voltammetry response showed a perfect liner range of 10⁻⁹–10⁻⁸ M with a correlation coefficient of 0.9969. The limit of detection (LOD) and the limit of quantitation (LOQ) are calculated to be 0.1 and 0.34 nM with a sensitivity of 19.05 μA·nM⁻¹, which is relatively excellent compared to other carbon-based electrodes. Meanwhile, the Bi@PG electrode showed tremendous potential in composite detection of multifold heavy metals (such as Pb²⁺ and Cd²⁺) and wider linear range.     

Biomass Straw-Derived Porous Carbon Synthesized for Supercapacitor by Ball Milling

A large amount of biomass straw waste is generated every year in the world, which can cause serious environmental pollution and resource waste if disposed of improperly. At present, biomass-derived porous carbon materials prepared from biomass waste as a carbon source have garnered attention due to their renewability, huge reserves, low cost, and environmental benevolence. In this work, high-performance carbon materials were prepared via a one-step carbonization-activation method and ball milling, with waste tobacco straw as precursor and nano-ZnO as template and activator. The specific surface area and porous structure of biomass-derived carbon could be controlled by carbonization temperature, which is closely related to the electrochemical performances of the carbon material. It was found that, when the carbonization temperature was 800 °C, the biochar possesses maximum specific surface area (1293.2 m²·g⁻¹) and exhibits high capacitance of 220.7 F·g⁻¹, at 1 A·g⁻¹ current density in a three-electrode configuration with 6 M KOH aqueous solution. The capacitance retention maintained about 94.83% at 5 A·g⁻¹ after 3000 cycles. This work proves the porous biochar derived from tobacco straws has a great potential prospect in the field of supercapacitors.     

Low Temperature Synthesis and Characterization of AlScMo3O12

Recent interest in low and negative thermal expansion materials has led to significant research on compounds that exhibit this property, much of which has targeted the A₂M₃O₁₂ family (A = trivalent cation, M = Mo, W). The expansion and phase transition behavior in this family can be tuned through the choice of the metals incorporated into the structure. An undesired phase transition to a monoclinic structure with large positive expansion can be suppressed in some solid solutions by substituting the A-site by a mixture of two cations. One such material, AlScMo₃O₁₂, was successfully synthesized using non-hydrolytic sol-gel chemistry. Depending on the reaction conditions, phase separation into Al₂Mo₃O₁₂ and Sc₂Mo₃O₁₂ or single-phase AlScMo₃O₁₂ could be obtained. Optimized conditions for the reproducible synthesis of stoichiometric, homogeneous AlScMo₃O₁₂ were established. High resolution synchrotron diffraction experiments were carried out to confirm whether samples were homogeneous and to estimate the Al:Sc ratio through Rietveld refinement and Vegard’s law. Single-phase samples were found to adopt the orthorhombic Sc₂W₃O₁₂ structure at 100 to 460 K. In contrast to all previously-reported A₂M₃O₁₂ compositions, AlScMo₃O₁₂ exhibited positive thermal expansion along all unit cell axes instead of contraction along one or two axes, with expansion coefficients (200–460 K) of α_a = 1.7 × 10⁻⁶ K⁻¹, α_b = 6.2 × 10⁻⁶ K⁻¹, α_c = 2.9 × 10⁻⁶ K⁻¹ and α_V = 10.8 × 10⁻⁶ K⁻¹, respectively.     

Humidity-Sensing Properties of an 1D Antiferromagnetic Oxalate-Bridged Coordination Polymer of Iron(III) and Its Temperature-Induced Structural Flexibility

A novel one-dimensional (1D) oxalate-bridged coordination polymer of iron(III), {[NH(CH₃)(C₂H₅)₂][FeCl₂(C₂O₄)]}_n (1), exhibits remarkable humidity-sensing properties and very high proton conductivity at room temperature (2.70 × 10⁻⁴ (Ω·cm)⁻¹ at 298 K under 93% relative humidity), in addition to the independent antiferromagnetic spin chains of iron(III) ions bridged by oxalate groups (J = −7.58(9) cm⁻¹). Moreover, the time-dependent measurements show that 1 could maintain a stable proton conductivity for at least 12 h. Charge transport and magnetic properties were investigated by impedance spectroscopy and magnetization measurements, respectively. Compound 1 consists of infinite anionic zig-zag chains [FeCl₂(C₂O₄)]_nⁿ⁻ and interposed diethylmethylammonium cations (C₂H₅)₂(CH₃)NH⁺, which act as hydrogen bond donors toward carbonyl oxygen atoms. Extraordinarily, the studied coordination polymer exhibits two reversible phase transitions: from the high-temperature phase HT to the mid-temperature phase MT at T ~213 K and from the mid-temperature phase MT to the low-temperature phase LT at T ~120 K, as revealed by in situ powder and single-crystal X-ray diffraction. All three polymorphs show large linear thermal expansion coefficients.