A Comparison of the ISO and AACC Methods for Determining the Activity of Trypsin Inhibitors in Soybean Meal

The international standard method for the determination of trypsin inhibitor activity (TIA) in soya products, ISO 14902, was compared with the American Association of Cereal Chemists’ standard AACC 22‐40.01 as modified by Hamerstrand in 1981 (AACC‐based method), using soybean meals as matrices. TIA, expressed as milligram of inhibited trypsin per gram of sample, was determined by both methods in each of 30 samples of soybean meal. TIA values according to ISO 14902 were significantly lower (P < 0.001) than those afforded by the AACC‐based method. This difference, which means that AACC‐based method and ISO 14902 TIA values are not directly comparable, is attributable to between methods differences, in decreasing order of influence: particle size (P < 0.01), trypsin inhibitor extraction method (P < 0.05), and trypsin substrate (P < 0.01). N‐benzoyl‐l ‐arginine‐4‐nitroanilide hydrochloride, the ISO 14902 trypsin substrate, affords TIA values 6.4 % higher than the racemic mixture used by the AACC method, but it seems unlikely that in most contexts this advantage would outweigh the disadvantage of its greater cost.     

Trypsin Inhibitor Assay: Expressing,Calculating, and Standardizing Inhibitor Activity in Absolute Amounts of Trypsin Inhibited or Trypsin Inhibitors

For expressing trypsin inhibitor activity (TIA), trypsin units inhibited (TUI), trypsin inhibited, and trypsin inhibitors have been used. Although the last two units are preferred, their calculations in current practices require refinement. With the proposed AOCS method Ba 12a-2020, four experiments were conducted, using four trypsin preparations having specific activity of 11,625, 12,602, 13,728, and 14,926 Nα-benzoyl-L-arginine ethyl ester (BAEE) units/mg protein, respectively. Experiment 1 determined the relationship between absorbance at 410 nm (A410) and trypsin concentration. Experiment 2 involved assaying raw and heated soybeans, expressing TIA as TUI/mg sample and μg trypsin inhibited/mg sample, and determining conversion factors between the two units. Experiment 3 resembled Experiment 2 except for using purified soybean Kunitz inhibitor (KTI) and Bowman-Birk inhibitor (BBI). Conversion factors determined correlated highly with trypsin-specific activity (R² = 0.9789). After standardizing against a reference trypsin having 15,000 BAEE units/mg protein, a standardized conversion factor of 0.03 A410 (1.5 TUI) = 1 μg trypsin inhibited was determined. It remained consistent regardless of trypsin specific activity, with or without inhibitors, and type of inhibitor samples. By using purified inhibitors (Experiment 3), conversion values between TUI and μg trypsin inhibitor and between μg trypsin inhibited and μg trypsin inhibitor could also be calculated, enabling expression of TIA in amounts of pure KTI, BBI or their equivalents. Furthermore, when the AOCS method was modified with half substrate concentration, half trypsin concentration or half both (Experiment 4), TIA values in TUI could change with modifications but values in mg trypsin inhibited (standardized) or trypsin inhibitor remained consistent.     

An International Collaborative Study on Trypsin Inhibitor Assay for Legumes,Cereals, and Related Products

For determining trypsin inhibitor activity (TIA) in soy products, the American Oil Chemists' Society (AOCS) Method Ba 12-75 has been used. It measures differences in absorbance at 410 nm of bovine trypsin activity toward a synthetic substrate (Nα-benzoyl-DL-arginine-p-nitroanilide) in the absence and presence of an inhibitor. Recently, a significantly improved method was developed (JAOCS, 2019, 96:635–645), featuring 5 mL of total assay volume, enzyme-last sequence, and single inhibitor level in duplicate. It is proposed as the AOCS Method Ba 12a-2020. As a part of the AOCS method approval process, a collaborative study involving 12 international laboratories was conducted to evaluate the performance of the proposed method. The study involved measuring TIA in 10 selected test samples plus a blind duplicate. They included soybeans, pulses, cereals, and their processed products (flours, concentrates, and isolates). After rigorous statistical treatment of the data, only three outliers were removed from the data of two samples. Repeatability relative standard deviations (RSDr) for the 11 samples ranged from 0.99% to 5.52%. Reproducibility RSD (RSD_R) ranged from 7.07% to 22.92%, with seven samples having RSD_R around 10% or less. The remaining four samples had very low TIA, and their RSD_R values ranged from 13.34% to 22.92%. The study has demonstrated reliable performance of the proposed AOCS method. Several collaborators carried out additional experiments addressing some aspects of the method, leading to further refinements. The proposed method is undergoing evaluation by the AOCS Uniform Methods Committee for adoption as an Official Method for measuring TIA in various legume and grain products.     

Soybean trypsin inhibitor and urease activities and their correlations as affected by heating method,duration, sample matrix,and prior soaking

Urease activity (UA) in soybeans has historically been measured to indicate heating inadequacy. Yet, over the years, controversy has emerged regarding the reliability of UA as a heating index and surrogate for trypsin inhibitor activity (TIA). In Experiments 1–4, raw soybean materials with different matrices (whole beans, flakes, full-fat and defatted flours) were selectively subjected to steaming, boiling, or dry oven toasting for various durations. For steaming or boiling soybeans, with or without prior soaking was another factor. Reduction rates of TIA and UA with heating time were compared, their correlation coefficients were determined and statistically treated. Experiment 5 entailed collecting 30 commercial soybean meals and measuring TIA and UA without further treatments. By combining the five experiments into a single study, the most comprehensive spectra regarding relative decreasing rates of TIA and UA with heating time and their correlations were obtained. Results show that the reduction rate of UA could be slower than, close to, or faster than that of TIA, depending on combinations of four factors (sample matrix, with or without prior soaking, heating method and interval). UA reached zero within shorter heating durations, while TIA maintained residual values at the longest durations. Consequently, positive correlations between TIA and UA varied from insignificant to very strong. UA was a reliable index for heating inadequacy and surrogate for TIA in soybean products heated by several single combinations of the four factors, but for those heated by other single or mixed combinations, it was unreliable, and TIA should be measured directly.     

Smectite quantification in sediments and soils by thermogravimetric analyses

A new method is assayed, consisting in measuring the weight loss between 100 and 450 °C of samples solvated with ethylene glycol and previously saturated in Mg. This approach allows an approximation to be made of the dioctahedral Al-rich smectite content in samples. The proportion of expandable material in the sample is calculated according to the following equation, obtained from artificial mixtures prepared with variable proportions of smectite: y = 3.96x − 4.05 (R² = 0.96), where x is the percentage of loss and y is the percentage of smectite in the sample. The slope of the equation agrees perfectly with the theoretical proportion of ethylene glycol in a solvated smectite, around 25%, and with the equivalent values determined on natural standards. In addition, the ordinate of the origin is also in agreement with the values of around 1% obtained in smectite-free samples. The method proposed is low-cost and easy to apply as a complement to X-ray diffraction determinations of expandable clay content in sediments and soils with the potential for landslides in civil engineering.     

Highly enhanced thermoelectric performance in BiCuSeO ceramics realized by Pb doping and introducing Cu deficiencies

In recent years, BiCuSeO oxyselenides have been developed as a promising thermoelectric material. In this article, Pb_xBi_1−xCu_1−ySeO (x = y = 0, 0.02, 0.04, 0.06, and 0.08) are prepared by solid-state reaction method and spark plasma sintering (SPS), and the combinatorial effects of Pb doping and Cu deficiencies on thermoelectric properties are investigated systematically. The transport properties are significantly enhanced due to the optimized carrier density, majorly contributing to the promotion of ZT values. As a result, the maximum ZT of 0.77 at 873 K and average ZT (from 300 to 873 K) of 0.50 are obtained for Pb_0.06Bi_0.94Cu_0.94SeO sample. The values are 0.4 and 1.2 times, respectively, higher than that of pristine sample.     

High Performance Liquid Chromatography–Size Exclusion Chromatography for Rapid Analysis of Total Polar Compounds in Used Frying Oils

Analysis of used frying oil samples by high performance liquid chromatography–size exclusion chromatography (HPLC–SEC or HPSEC) was compared to AOCS Official Method Cd 20-91 (silica gel column chromatography) for the purpose of developing a rapid analysis of total polar compounds (TPC). In a direct comparison of the two analytical methods using four different sets of used frying oils (21 total oil samples) ranging from fresh to discard quality (4.3 to 35.4% TPC by column chromatography), the weight percent total polar compounds (%TPC) determined by HPLC–SEC averaged 0.71% higher than the values by silica gel column chromatography. Reproducibility of the HPLC–SEC method of s _r = 0.30 and RSD_r% = 1.22 compares to the variability of s _r = 0.29 and RSD_r = 1.3 for samples of approximately the same %TPC, reported in AOCS Method Cd 20-91. Because the rapid method does not separate pure (non-polar) triacylglycerol (TAG) and polar, oxidized TAG (OX-TAG), a high concentration of OX-TAG will quantitatively affect the results. This places practical limits on the types of studies to which the method may be applied if a separate analysis for the OX-TAG is not performed. Advantages of the HPLC–SEC method include the following. It uses about 75% less solvent than standard column chromatography methods for determination of %TPC. This HPLC–SEC method is very similar to AOCS Official Method Cd 22-91, and thus, also separates and quantifies polymerized triacylglycerols. The HPLC–SEC method determines both TAG polymer concentration and %TPC of used frying oils in about 1 h.     

Optimized sintering behavior and microwave dielectric properties of Ca1+2xSnSi2x+yO3+6x+2y by composition modulation

Ca_1+2xSnSi_2x+yO_3+6x+2y (0.1 ≤ x ≤ 0.9; 0.1 ≤ y ≤ 0.9) microwave dielectric ceramics were prepared through traditional solid-state reaction sintered at 1450°C–1500°C for 5 hours. The Ca₃SnSi₂O₉ second phase replaced the SnO₂ second phase of the Ca_1+2xSnSi_2xO_3+6x (x = 0, y = 0) ceramics by controlling the ratio of Ca:Sn:Si. The cracks of CaSnO₃ (x = 0, y = 0) ceramic were inhibited, the microwave dielectric properties were optimized by introducing the Ca₃SnSi₂O₉ second phase, and the CaSnO₃-Ca₃SnSi₂O₉ mixture system existed at (0.1 ≤ x ≤ 0.9, y = 0). The CaSnSiO₅ phase with positive τ_f value was related to the Si-rich in CaSnSi_yO_3+2y (x = 0; 0.1 ≤ y ≤ 0.9), and the coexistence of three and four phases was obtained at CaSnSi_yO_3+2y (0.1 ≤ y ≤ 0.9) ceramics. The CaSnSiO₅ phase appeared at CaSnSi_yO_3+2y (0.3 ≤ y ≤ 0.9) ceramics. The CaSnSi_yO_3+2y (y = 0.8) ceramic with 49.2 wt% CaSnSiO₅ phase exhibited excellent microwave dielectric properties: ε_r = 11.06, Q × f = 57,500 GHz (at 11.5 GHz), and τ_f = +8.1 ppm/°C.     

Oxygen octahedra distortion-induced multiferroic properties of Er and Zr co-doped BiFeO3 nanoparticles

The present work unveiled the distortion of oxygen octahedra influencing magnetic and magnetoelectric properties of novel Bi_1−xEr_xFe_1−yZr_yO₃ (x = 0, .05, .1, y = .02, .05) polycrystalline nanoparticles by sol–gel route. X-ray diffraction patterns analysis reveals that pristine BiFeO₃ and doped BiFeO₃ are crystalized in the rhombohedral structure (R3c). The Fe–O–Fe bond angle of Bi_1−xEr_xFe_1−yZr_yO₃ (x = 0, .05, .1, y = .02, .05) varies between 141° and 159.62° as the concentration of Er (via Bi site) and Zr (via Fe site) ions increases in BiFeO₃. As a result, the tilt angle of oxygen octahedra and the canting angle of spiral spin arrangement increase. Hence, the maximum magnetization varies between .03144 and .37558 emu/g in Er and Zr co-doped BiFeO₃ system. The number of electrons per unit cell of Bi_1−xEr_xFe_1−yZr_yO₃ (x = 0, .05, .1, y = .02, .05) lies between 733.38 and 831, respectively. Further, the number of coherently diffracting domains increases from 3.07 to 5.21, and then it decreases when Er and Zr are increased in BiFeO₃. Consequently, the magnetoelectric coupling coefficient varies between .0265 and .2511 mV/cm Oe, respectively. Particularly, Bi_0.95Er_0.05Fe_0.98Zr_0.02O₃ shows enhanced magnetic and magnetoelectric behaviors compared to other samples.     

Layered NdBaCo2−xNixO5+δ perovskite oxides as cathodes for intermediate temperature solid oxide fuel cells

The effect of Ni substitution on the crystal chemistry, thermal and electrochemical properties, and catalytic activity for oxygen reduction reaction of the layered NdBaCo_2−xNi_xO_5+δ perovskite oxides has been investigated for 0 ≤ x ≤ 0.6. The oxygen content (5 + δ) and oxidation state of the (Co, Ni) ions in the air-synthesized NdBaCo_2−xNi_xO_5+δ samples decrease with increasing Ni content, accompanied by a structural transition from tetragonal (0 ≤ x ≤ 0.4) to orthorhombic (x = 0.6). Similarly, the thermal expansion coefficient (TEC) and electrical conductivity also decrease with increasing Ni content. The x = 0.2 and 0.4 samples exhibit slightly improved performance as cathodes in single cell solid oxide fuel cell (SOFC) compared to the x = 0 sample, which is in accordance with the ac-impedance data. Among the samples studied, the x = 0.4 sample exhibits a combination of low thermal expansion and high catalytic activity for the oxygen reduction reaction in SOFC.     

The relationship between crystal structure and modified microwave dielectric properties of Ca3SnSi2-xGexO9 ceramics

Ca₃SnSi_2-xGe_xO₉ (0 ≤ x ≤ 0.8) and (1–y) Ca₃SnSi_1.6Ge_0.4O₉ – y CaSnSiO₅ – 2 wt% LiF (y = 0.4 and 0.5) microwave dielectric ceramics were prepared by traditional solid-state reaction through sintering at 1250°C–1425°C for 5 h and at 875°C for 2 h, respectively. Ge⁴⁺ replaced Si⁴⁺, and Ca₃SnSi_2-xGe_xO₉ (0 ≤ x ≤ 0.4) solid solutions were obtained. At 0.1 ≤ x ≤ 0.4, the Ge⁴⁺ substitution for Si⁴⁺ decreased the sintering temperature of Ca₃SnSi_2-xGe_xO₉ from 1425 to 1300°C, the SnO₆ octahedral distortions, and the average CaO₇ decahedral distortions, which affected the τ_f value. The large average decahedral distortions corresponded with nearer-zero τ_f values at Ca₃SnSi_2-xGe_xO₉ (0.1 ≤ x ≤ 0.4) ceramics. The τ_f value and sintering temperature of Ca₃SnSi_2-xGe_xO₉ (x = 0.4) ceramic were adjusted to near-zero by CaSnSiO₅ and decreased to 875°C upon the addition of 2 wt% LiF. The (1 – y) Ca₃SnSi_1.6Ge_0.4O₉ – y CaSnSiO₅ – 2 wt% LiF (y = 0.5) ceramic sintered at 875°C for 2 h exhibited good microwave dielectric properties: ε_r = 10.3, Q × f = 14 300 GHz (at 12.2 GHz), and τ_f = ‒5.8 ppm/°C.     

Optimization of electrical conductivity in the Na2O-P2O5-AlF3-SO3 glass system

We report on the individual roles of charge carrier density and network modification in sodium ion conducting glasses from the Na₂O-P₂O₅-SO₃-AlF₃ (NAPFS) system. For this, a broad range of glass compositions was considered across the series of 44Na₂O/(56 – x − y)P₂O₅/xAlF₃/ySO₃, 47Na₂O/(53 − x − y)P₂O₅/xAlF₃/ySO₃, and 50Na₂O/(50 − x − y)P₂O₅/xAlF₃/ySO₃, with x = 8, 12, 16, 20 and y = 0, 5, 7, 10, 12. Impedance spectroscopy was conducted on these glasses at frequencies from 10⁻² to 10⁶ Hz and over temperatures from 50 to 250°C, and complemented by structural analyses using Raman spectroscopy and nuclear magnetic resonance data. While the trends in dc conductivity and activation energy follow that of Na₂O content (increasing from 44 to 50 mol%), substantial enhancement of conductivity (by about two orders of magnitude) and correspondingly lower activation energy were also found for constant Na₂O concentration when adjusting SO₃ or AlF₃ within specific limits of glass structure.     

New sulfur adsorbents derived from layered double hydroxides: I: Synthesis and COS adsorption

Mixed oxides, prepared via the thermal decomposition of layered double hydroxides (LDHs), were screened gravimetrically for their ability to adsorb carbonyl sulfide (COS). Based on promising results obtained for Ni/Mg/Al, Ni/Mg/Fe and Co/Mg/Al mixed oxides, a study was undertaken to optimize the composition of these materials for COS adsorption. To investigate the effect of the M(II):M(III) ratio, LDHs of the type [M_zMg_yAl_x(OH)₂](CO₃)_x/2·0.5H₂O (where M = Ni or Co, and x + y + z = 1) were prepared at values of x corresponding to 0.33 and 0.20. Simultaneously, the elemental ratio of transition metal to magnesium (z/y) was varied. Mixed oxides obtained from the resulting LDHs were tested in fixed bed mode with a feed of 100 ppm COS in N₂ to determine breakthrough capacity. In general Ni/Mg/Al mixed oxides showed the best performance, a composition with Ni/Mg/Al = 0.32/0.48/0.20 showing the best adsorption capacity. Treatment of the spent adsorbent under an atmosphere of 5% H₂ in N₂ at 450 °C was found to provide an effective means of restoring the adsorption capacity over two cycles of adsorption and regeneration, although after three such cycles, adsorption capacity decreased.     

Synthesis and Properties of Novel Double-Tail Trisiloxane Surfactants

To improve the hydrolysis resistant ability of trisiloxane surfactants, ethoxylated single-tail and double-tail trisiloxane surfactants of the general formulas Me₃SiOSiMeR¹OSiMe₃ (R ¹ = (CH₂)₃NHCH₂CH(OH)CH₂(OCH₂CH₂) _x OCH₃; x = 8.4, 12.9, 17.5, 22) and Me₃SiOSiMeR²OSiMe₃ (R ² = (CH₂)₃NR³CH₂CH(OH)CH₂(OCH₂CH₂) _x OCH₃; R ³ = CH₂(CH₂) _y CH₃; x = 8.4, 12.9, 17.5, 22; y = 2, 6) were synthesized. Their structures were characterized by ¹H NMR and ¹³C NMR. The surface activity and hydrolysis resistant properties of the trisiloxane surfactants prepared were also studied. The values of the critical micelle concentration of all trisiloxane surfactants prepared were at levels of 10⁻⁵ and 10⁻⁴ mol/L. They can reduce the surface tension of water to less than 24 mN/m. The hydrolysis resistant properties of double-tail trisiloxane surfactants are superior to those of single-tail trisiloxane surfactants. The double-tail trisiloxane surfactants 1B (x = 8.4; y = 2) and 2C (x = 12.9; y = 6) can be stable for 8 days in an acidic solution (pH 4.0) and 11 days in an alkaline environment (pH 10.0).     

Empirical models for layered A-site ordering in perovskite titanates

In industry and labs, predictive models describing processing-structure relationships are inherently valuable, yet few exist for cation ordering in perovskites. In this work, 15 compositions in the [(Na_yLi_1−y)_(1−3x)/2La_(1+x)/2]TiO₃ (NLLT) system (y = 0.25, 0.5, and 0.75; x = 0, 0.0533, 0.1, 0.1733, and 0.225) were synthesized using a conventional solid-state mixed-oxide method. X-ray diffraction data show that some degree of long-range ordering of A-site cations exists for x ≥ 0.1, although electron-diffraction data indicate that short-range ordering exists even for x < 0.1, with the degree of ordering decreasing as the value of x increases. Empirical models have been derived for the A-site ordering parameter (η) as well as the resultant expansion (Δr_A) for each y series in the NLLT system, from which two general models were derived for perovskites with any arbitrary degree of 1:1 layered A-site ordering. These general models allow for the prediction of the order parameter and resulting expansion using only published ionic radii data.     

Realizing the invariant electrostrain response and low hysteresis via multicomponent coordination in Pb-based ceramics

High-performance piezoelectric materials are essential in many piezoelectric devices. However, the composition of piezoelectric materials usually has a great influence on their performance. In this work, xBi(Mg_1/2Ti_1/2)O₃–yPbZrO₃–zPbTiO₃ (xBMT–yPZ–zPT; 0.2 ≤ x ≤ 0.4, 0.25 ≤ y ≤ 0.4, and 0.35 ≤ z ≤ 0.4) ternary ceramics with different compositions were synthesized and it was found that the strain response was not sensitive to the composition. The crystal structure, strain response, ferroelectric properties, and temperature stability of xBMT–yPZ–zPT ceramics were investigated in detail. X-ray diffraction patterns show that all the as-prepared xBMT–yPZ–zPT ceramics with x = 0.2, 0.3, 0.4, and 0.5 possess a perovskite structure. Under an external electric field of 6 kV mm⁻¹, the strain values of xBMT–yPZ–zPT ternary ceramics with x = 0.2, 0.3, 0.4, and 0.5 were 0.30%, 0.31%, 0.30%, and 0.27%, respectively. In addition, the strain hysteresis of these ternary ceramics is also almost the same and low. These merits make xBMT–yPZ–zPT piezoelectric ceramics have broad application prospects in the field of commercial actuators.     

Magnetic and Cytotoxicity Properties of La1−x Sr x MnO3 (0 ≤ x ≤ 0.5) Nanoparticles Prepared by a Simple Thermal Hydro-Decomposition

This study reports the magnetic and cytotoxicity properties of magnetic nanoparticles of La_1−x Sr _x MnO₃ (LSMO) with x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5 by a simple thermal decomposition method by using acetate salts of La, Sr, and Mn as starting materials in aqueous solution. To obtain the LSMO nanoparticles, thermal decomposition of the precursor was carried out at the temperatures of 600, 700, 800, and 900 °C for 6 h. The synthesized LSMO nanoparticles were characterized by XRD, FT-IR, TEM, and SEM. Structural characterization shows that the prepared particles consist of two phases of LaMnO₃ (LMO) and LSMO with crystallite sizes ranging from 20 nm to 87 nm. All the prepared samples have a perovskite structure with transformation from cubic to rhombohedral at thermal decomposition temperature higher than 900 °C in LSMO samples of x ≤ 0.3. Basic magnetic characteristics such as saturated magnetization (M _S) and coercive field (H _C) were evaluated by vibrating sample magnetometry at room temperature (20 °C). The samples show paramagnetic behavior for all the samples with x = 0 or LMO, and a superparamagnetic behavior for the other samples having M _S values of ~20–47 emu/g and the H _C values of ~10–40 Oe, depending on the crystallite size and thermal decomposition temperature. Cytotoxicity of the synthesized LSMO nanoparticles was also evaluated with NIH 3T3 cells and the result shows that the synthesized nanoparticles were not toxic to the cells as determined from cell viability in response to the liquid extract of LSMO nanoparticles.     

Novel color tunable LaCaGaO4:Bi3+,Eu3+ phosphors for high color rendering warm white LEDs

A series of LaCaGaO₄:xBi³⁺,yEu³⁺ (x = 0.002–0.04, y = 0.02–0.45) phosphors with adjustable emission colors were synthesized by high-temperature solid-state reaction. The samples were identified as pure phases by X-ray diffraction and Rietveld refinement, and the crystal structures were analyzed in detail. The LaCaGaO₄:xBi³⁺ phosphor shows an intense blue emission under near-ultraviolet excitation, originating from the ³P₁ → ¹S₀ transition. The spectrum analysis reveals that the Bi³⁺ ions occupy two luminescence centers in the LaCaGaO₄ host and that energy transfer can occur. A model of the energy transfer between the Bi³⁺ and Eu³⁺ ions was also created and studied in detail. As the Eu³⁺-concentration increased, the emission color of the LaCaGaO₄:0.005Bi³⁺,yEu³⁺ phosphor changed from blue to pink to red. In addition, the fluorescence lifetime, quantum yield, thermal stability, and other properties of the phosphors were characterized and analyzed. Finally, two white light-emitting diode devices with R_a values of 96.6 and 95 and correlated color temperatures of 4578 and 3324 K were fabricated, indicating the potential of phosphors for warm white lighting applications.     

Ca-doped PrBa1-xCaxCoCuO5+δ (x = 0–0.2) as cathode materials for solid oxide fuel cells

Ca-doped perovskite oxides PrBa_1-xCa_xCoCuO_5+δ (PBCCCO, x = 0–0.2) were prepared and investigated as SOFC cathode materials. PBCCCO samples are single perovskite structure with P4/mmm space group. Pr, Cu and Co ions in PBCCCO samples exist in the form of Pr³⁺/Pr⁴⁺, Cu²⁺/Cu⁺ and Co³⁺/Co⁴⁺ multi-valence states. The average TECs of PBCCCO samples were reduced from 17.4 × 10^?6 K^?1 (x = 0) to 16.7 × 10^?6 (x = 0.1) and 16.1 × 10^?6 K^?1 (x = 0.2) whin RT-900°С. The electrical conductivity and electrochemical catalytic activity of PBCCCO perovskites was enhanced obviously by Ca doping. The ASR values decreased by 60.1% (@650 °C), 68.9% (@700 °C), 71.0% (@750 °C) and 72.8% (@800 °C) respectively when Ca doping content increased from x = 0 to 0.2. These results suggest PBCCCO sample with Ca doing content x = 0.2 can be a promising cathode for IT-SOFC.     

Thermoelectric properties of a series of polycrystalline Mo(Se1−xTex)2

Transition metal dichalcogenides have being actively studied on the account of their large density-of-state effective mass and low lattice thermal conductivity. Herein, thermoelectric and electrical transport properties of MoSe₂–MoTe₂ system are investigated. A series of Mo(Se_1−xTe_x)₂ (x = 0, .25, .5, .75, and 1) polycrystalline samples was synthesized by conventional solid-state reaction. Single hexagonal phase was identified for each sample without secondary phase, confirming the formation of complete solid solutions between MoSe₂ and MoTe₂. The electrical conductivity and magnitude of the Seebeck coefficient increased simultaneously with increasing Te content x at high temperatures, with the power factor following the same trend. As results, the MoTe₂ sample exhibited the maximum power factor of .014 mW/(m K²) at 823 K. The lattice thermal conductivities of the alloyed samples (x = .25, .5, and .75) significantly decreased compared to MoSe₂ and MoTe₂ owing to point defect phonon scattering via anion substitution, which is verified by the Debye–Callaway model. A maximum zT of .0044 was obtained for MoTe₂ sample at 773 K; however, the calculated quality factor B values of the samples with x = .75 and 1 at 773 K were almost identical, suggesting that a further enhancement of zT can be achieved by optimizing an n_H of the Mo(Se_0.25Te_0.75)₂ sample.