Metal Ion‐Catalyzed Hydrothermal Liquefaction of Calcium Lignosulfonate in Subcritical Water

Three metal ion catalysts, namely, Na⁺, K⁺, and Ca²⁺, were tested to improve liquefaction of calcium lignosulfonate, and their effects on product distribution were specifically investigated. Results showed that metal ion catalysts favored the production of hydrogen as well as of phenolic compounds. The total contents of phenolic compounds catalyzed by metal ions were generally higher than 75 %. The catalysis abilities of Na⁺ and K⁺ were better than that of Ca²⁺. The neutral‐alkaline condition was much more beneficial to calcium lignosulfonate liquefaction. Compared to the hydrochars with Na⁺ and K⁺ catalysts, the hydrochars with Ca²⁺ catalyst had higher carbon content and a higher heating value.     

Adhesion of a chemically deposited monetite coating to a Ti substrate

Monetite is a promising biomaterial for restoring the function of the compromised skeletal structures due to its superior osteoconductive and resorption properties. However, its potential as a coating for orthopaedic implants in load bearing applications has not yet been investigated. The aim of this study was to prepare monetite coating on Ti substrate in mild conditions, which may allow incorporation of protein-based drugs during the coating deposition. Coatings were prepared using chemical deposition of monetite on Ti substrate in acidic conditions at 75 °C for 24 h. Coatings were characterised by scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Adhesion of the coatings to Ti substrate was measured using tensile tests. EDS confirmed the calcium phosphate nature of the coating and XRD and FTIR confirmed the monetite phase of the coatings. SEM revealed that the coatings were formed of densely packed plate-like monetite crystals, with the crystal size approximately 20 × 10 × 5 μm. Adhesion tests showed cohesive failure of the monetite coatings and the tensile strength of the coating was in the range of 15.43 ± 0.20 MPa. Mechanical tests showed that monetite coatings were stable and could be considered for use with Ti orthopaedic implants.     

Co-Free High-Entropy Alloys Powders Immobilized by Electrospray and Microf luidics for Decolorization of Azo Dye

In recent years,high-entropy alloys(HEAs) have received more and more attention due to their unique microstructure and properties.Several researchers have reported that some ball-milled(BM) HEAs powders possess prominent decolorization performance for azo dyes.Three kinds of Co-free HEA powders(AlCrFeMn,AlCrFeNi and FeCrNiMn) have been synthesized by ball milling in this work,of which AlCrFeMn shows the best decolorization efficiency for DB6 aqueous solution.However,at this time,the BM HEAs are in powder state and not easy to be reused,so the loss rate of the powders is high during the reaction.Sometimes,the reaction between reacted the powders and the dye solution is too fast to control.While,in order to solve these problems,this work proposes to immobilize bare BM AlCrFeMn HEA powders in calcium alginate beads(CAB s) by electrospray and microfluidics.Through four cycles of reaction,the loss rate of the AlCrFeMn powders can be reduced from 40 to 5 wt% if the powders are immobilized by CABs with an average diameter of 0.55 mm obtained at the DC voltage of 30 kV.In addition,in the four cycles of experiment,the AlCrFeMn HEA-CABs with an average diameter of0.55 mm shows better stability and easier separation than that of the bare AlCrFeMn powders.These findings provide new ideas for HEAs to decolorize azo dyes and are of great significance for protecting freshwater resources.     

Assessment of intradialysis calcium mass balance by a single pool variable‐volume calcium kinetic model

Introduction: A reliable method of intradialysis calcium mass balance quantification is far from been established. We herein investigated the use of a single‐pool variable‐volume Calcium kinetic model to assess calcium mass balance in chronic and stable dialysis patients. Methods: Thirty‐four patients on thrice‐weekly HD were studied during 240 dialysis sessions. All patients were dialyzed with a nominal total calcium concentration of 1.50 mmol/L. The main assumption of the model is that the calcium distribution volume is equal to the extracellular volume during dialysis. This hypothesis is assumed valid if measured and predicted end dialysis plasma water ionized calcium concentrations are equal. A difference between predicted and measured end‐dialysis ionized plasma water calcium concentration is a deviation on our main hypothesis, meaning that a substantial amount of calcium is exchanged between the extracellular volume and a nonmodeled compartment. Findings: The difference between predicted and measured values was 0.02 mmol/L (range ?0.08:0.16 mmol/L). With a mean ionized dialysate calcium concentration of 1.25 mmol/L, calcium mass balance was on average negative (mean ± SD ?0.84 ± 1.33 mmol, range ?5.42:2.75). Predialysis ionized plasma water concentration and total ultrafiltrate were the most important predictors of calcium mass balance. A significant mobilization of calcium from the extracellular pool to a nonmodeled pool was calculated in a group of patients. Discussion: The proposed single pool variable‐volume Calcium kinetic model is adequate for prediction and quantification of intradialysis calcium mass balance, it can evaluate the eventual calcium transfer outside the extracellular pool in clinical practice.     

Kinetics and mechanistic studies of methane dry reforming over Ca promoted 1Co–1Ce/AC-N catalyst

The mechanism and kinetic features of dry reforming with methane (DRM) over Ca promoted 1Co–1Ce/AC-N catalyst was investigated. The mechanistic pathway studies have conducted by FTIR and XPS analysis, structure-activity correlations demonstrated the CH₄ and CO₂ could adsorb on catalyst active sites and generate intermediate CH_x, OH and CH_xO, continue to generate CO and H₂ and then desorbed from active sites. Moreover, CH₄ could also oxidized by Ce⁴⁺ and CO₂ reduced by Ce³⁺, the same content of Ce⁴⁺ and Ce³⁺ on promoted catalyst greatly improved the reaction rate. The kinetic of dry reforming with methane was examined for temperature between 650 and 850 at 800 °C. The research was carried out by changing the CH₄/CO₂ ratios between 0.3 and 3.0. The obtained experiment data were fitted by three typical kinetic models (Power Law, Eley-Rideal and Langmuir-Hinshelwood), the fitting results demonstrated that the best prediction of reforming rates can provided by Langmuir-Hinshelwood model for the reaction temperatures between 650 and 800 °C. Moreover, activation energies of methane and carbon dioxide consumption were ?117 and ?47 kJ/mol, indicating that much higher energy barrier is needed for methane activation compared to carbon dioxide.     

Electric transport properties of rare earth doped YbxCa1-xMnO3 ceramics (part I: Optimization of ceramic processing)

A comprehensive study was performed in order to find the effect of different calcination and sintering conditions on the physical properties of calcium manganite ceramics in dependence of temperature T and partial pressure of oxygen p(O₂). The eventual formation of oxygen vacancies during sintering was investigated and the results were confirmed by monitoring the release of oxygen using a ZrO₂ oxygen sensor. The phase transition behavior was studied using thermogravimetric analysis (TGA) in a wide range of p(O₂) ≈ 10^?1 MPa down to 10^-19 MPa at high temperatures accompanied by dilatometry- and XRD-measurements. Furthermore, the present study reveals for the first time a way for reducing and preventing crack formation that may occur during sintering. The present systematic research provides essential fundamental information before performing electrical measurements necessary in order to understand important factors about charge carriers and electrical transport mechanism.     

Synthesis of a Porous Nano‐CaO/MgO‐Based CO2 Adsorbent

A porous nano‐CaO/MgO‐based adsorbent was prepared using MgO as a support in order to increase the sorption capacity and durability. The magnesium sol prepared by reacting MgO slurry with citric acid was added to nano‐CaCO₃ slurry and the mixture was calcinated to obtain the nano‐CaO/MgO‐based adsorbent. The influence of MgO content on the structure and sorption performance of the resulting adsorbent was studied in detail. The pore radius and specific surface area of the adsorbent increased with higher MgO content. The adsorbent exhibited superior sorption performance during calcium looping and maintained a good durability at the calcination temperature, thus being an interesting candidate for future work.     

Formation and decomposition of C4F7 type calcium ferrites in superfluxed magnetite based pellets during oxidation and reduction

Abstract

In the current work the reactions of magnetite based pellets with large additions of calcite (3%CaO) during reduction have been investigated. This made it possible to use both X-ray diffraction (XRD) and scanning electron microscopy (SEM) to detect reaction phases that normally occur in very small amounts. The main binding phase in the pellets after oxidation was (CaO,MgO,FeO)₄(Fe₂O₃)₇, whereas the one commonly reported in the literature is (CaO)(Fe₂O₃)₂. During reduction at 500–700°C severe cracking occurred in these pellets, especially in the calcium ferrite phase. However, the decomposition of this phase began at 600°C, and therefore it is believed that the reason for the cracks is low strength of the phase itself, rather than weakness induced by reduction of the phase. Upon reduction of magnetite into wüstite at 800°C, the calcium began dissolving in the wüstite, and at 900°C porous calciowüstite had formed in the entire sample, except for some remaining magnetite left in the pellet cores.     

The influence of additives on properties of heat‐induced gels from salt‐soluble proteins extracted from goose

Calcium chloride (CaCl₂) and phosphates are important additives to improve product quality during meat processing. Response surface methodology was used to study the influence of CaCl₂ and phosphates on the hardness, water‐holding capacity (WHC) and ultra‐structure of salt‐soluble goose meat protein gels. The results show that the hardness and WHC of salt‐soluble protein gels increased significantly when CaCl₂ concentration was increased and phosphates were added. Scanning electron microscopy showed that tetrasodium pyrophosphate (TSPP) and sodium tripolyphosphate (STPP) had a greater impact on the cross‐linking and pore diameter of the gel networks than sodium hexametaphosphate (SHMP). At the 0.02 m and 4:3:2 of CaCl₂ concentration and the ratio of TSPP, SHMP and STPP, hardness and WHC values were 114.55 gf and 96.65%, which corresponded to the prediction value of our model. Further results showed that the hardness and WHC of gels reached the maximum with 0.3% of phosphates levels.