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A kind of multiscale β-sialon grain-reinforced Al2O3 matrix composite ceramic tool material, named ASN, was prepared and studied. For the ASN, β-sialon (molecular formula: Si4Al2O2N6) was synthesized in situ by a hot-pressing and solid-solution reaction process. A total of six samples were prepared at varying sintering temperatures and holding times under vacuum conditions. The solid solution reaction mechanism of β-sialon, the phase composition, mechanical properties, microstructure, and strengthening and toughening mechanisms of the composite ASN were investigated. As a result, within the experimental parameters, an optimal ASN tool material was obtained under a pressure of 32 MPa and at a temperature of 1550 °C for 20 min. The tested mechanical properties of the optimal sample were as follows: flexural strength 997 ± 59 MPa, fracture toughness 6.4 ± 0.3 MPa·m1/2, Vickers hardness 18.2 ± 0.4 GPa, and relative density 98.1 ± 0.2%. According to crystal defect theory, the solid solution reaction mechanism of in-situ-synthesized β-sialon in an Al2O3 matrix involves a double mechanism of unequivalence (or hetero-valence) and interstitial filling. The multiscale β-sialon grains mainly consisted of four grains, which were elongated β-sialon grains with a diameter of 0.3–0.4 μm and an aspect ratio of 6–9, elongated β-sialon grains with a diameter of 70 nm and an aspect ratio of 10, β-sialon whiskers with a diameter of 0.2 μm and an aspect ratio of 12–15, and intragranular β-sialon whiskers with a diameter of 70 nm. The mechanical properties were improved due to strengthening and toughening mechanisms, such as mixed structure mode (intergranular and transgranular), elongated grain pullout, interface bonding, crack reflection, pinning, and bridging. [ABSTRACT FROM AUTHOR]

To investigate the nucleation behavior of ammonium sulphate, commonly used as a fertilizer, during cooling crystallization, polythermal methods have been used to determine the metastable zone widths (MSZWs) of ammonium sulphate in aqueous solution from the saturation temperature at 288.15 to 317.15 K under cooling rates of 6.0 to 30.0 K per hour. MSZWs increased with the increasing cooling rate and the saturation temperature. Based on classical nucleation theory, the nucleation potential model linked the MSZWs to the critical nucleation potential and pre-exponential factor. The MSZWs from one saturation temperature or with one cooling rate were used to predict the MSZWs with other saturation temperatures or with other cooling rates, by the nucleation potential model. The estimated MSZWs were compared with the experimental values. Further, according to the characteristics of the electrolyte solution, the supersaturation term in the nucleation potential model was modified by the activity coefficient. The estimated MSZWs showed improved accuracies and a tendency to be positively correlated with both the supersaturation temperature and cooling rate, which was consistent with the experimentally measured MSZWs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Draw the ternary phase diagram of racemic threonine in water/methanol. • Analyze the binary phase diagrams of melting points composed of different ratios of threonine enantiomers. • Explore common determinations of the racemic system and compare the characteristics of different racemates. • Correlate solubility data with modified Apelblat model, Wilson model, and NRTL model derived from the factor of temperature. • Correlate solubility data to Jouyban-Acree model and Machatha model in terms of solvent composition. Phase equilibrium behaviors of chiral racemic threonine, as well as D-Threonine and L-Threonine, have been systematically investigated. The PXRD patterns, DSC, and ternary phase diagram exhibited the typical characteristics of the conglomerate. As an essential basis for ternary phase diagrams, the solubility of D-Threonine, L-Threonine, and the racemic mixture was measured at a temperature range from 283.15 K to 308.15 K in both water/methanol and water/ethanol mixtures. The solubility of a single enantiomer was at a range from 1.08 to 2.23 (S, wt %) in water/methanol = 6/4 v/v and from 0.36 to 0.91 (S, wt %) in water/methanol = 4/6 v/v. The racemate exhibited a double solubility of the single enantiomer. Subsequently, the experimental solubility data showed promising correlations with five thermodynamic models: Jouyban-Acree equation, Machatha model, the modified Apelblat model, Wilson model, and NRTL model. The modified Apelblat model was the best-fit model when the temperature was primarily considered. Whereas Jouyban-Acree model demonstrated better alignment when the solvent composition was mainly regarded. Besides the above approaches for the determination of chiral drug systems, the results were analyzed in the different characteristics between the racemate and the single pure enantiomer. Selecting the appropriate model to correlate with solubility data can facilitate the exploration of the ternary phase diagram of chiral drugs under different conditions, thus favoring the subsequent enantiomeric separation and industrial production. [ABSTRACT FROM AUTHOR]

The purpose of this work is to investigate the effect of the WC content on the surface characteristics and nanoindentation behaviors of WC/Ni-based composite laser-clad coatings. Four NiCrSiBC coatings with WC wt% of 30%, 40%, 50%, and 60%, respectively, were clad on carbon steel substrates using a laser. The morphologies and phase compositions of four clad coatings were comparatively observed. In addition, the hardness and elastic modulus values of the four coatings were measured and quantitatively calculated. As a result, with the increase in WC, the coating grains were more refined. Meanwhile, cracks and WC particle breakage occurred in the 50–60% WC coatings, whereas this was not found in the 30–40% WC coatings. When the WC content increased from 40% up to 50%, the coating hardness and elastic modulus significantly increased. However, a further increase in WC from 50% to 60% did not result in considerable improvement in coating quality but considerably worsened the coating's cracking behavior instead. Therefore, for WC/Ni-based composite coatings, a threshold exists for the WC content, and this value was 50% within the experimental scope of this study. [ABSTRACT FROM AUTHOR]

Background: Lignin played an important role in the establishment of coated fertilizers coating material as a substitute for petrochemical raw materials. However, so far, the lignin-based coated fertilizers was limited in only the poor slow-release performance. To achieve good slow-release performance of lignin-based coated fertilizers, hydrophilic of lignin need to be resolved to establish an green and better controllable lignin-based coated fertilizers. Results: In the study, a novel green double layer coating with lignin-based polyurethane (LPU) as the inner coating and epoxy resin (EP) as the outer coating was effectively constructed for coated urea. Fourier transform infrared spectra confirmed that lignin and polycaprolactone diol successfully reacted with Hexamethylene diisocyanate. The loss weight and water contact angle (WCA, 75.6–63.6°) of the LPUs decreased with the increased lignin content. The average particle hardness of the lignin-based double-layer coated urea (LDCU) first increased from 58.1 N (lignin of 30%) to 67.0 N (lignin of 60%), but then decreased to 62.3 N (lignin of 70%). The release longevity of the coated urea was closely related to the preparation parameters of the coating material. The optimal cumulative nutrient release rate (79.4%) of LDCU was obtained (lignin of 50%, –CNO/–OH molar ratios of 1.15, EP of 35%, and coating ratio of 5%). The aggregates of hydrone on the LDCU caused the dissolution and swelling of nutrients, and then the diffusion of nutrients through the concentration gradient. Conclusions: A though the nutrient release of the LDCUs was affected by many factors, the successful development of the LDCUs will help improve the rapid development of the coated fertilizer industry. [ABSTRACT FROM AUTHOR]

Novel lignin/paraffin/epoxy resin composite coated urea (LPECCU) was successfully prepared. Paraffin and epoxy resin (ER) were used to improve the slow-release properties of the lignin-based polyurethane (LPU) coated urea. The relationships among the N release characteristics, liquid-solid rate, –CNO/–OH molar rate and film formation rate in the coating material of LPECCU were investigated. The results showed that the water contact angle (WCA) of the LPU-paraffin increased with the rate of liquid-solid rate (73.61–88.19°) and –CNO/–OH molar rate (65.17–82.24°) increased. The average particle hardness of LPECCU decreased with the increased of liquid-solid rate (57.10–66.80 N) and the reduced of –CNO/–OH molar rate (48.11–63.00 N). The LPECCU emerged compact micro-structure, low sustained release and high compressive resistance by adding paraffin and ER. The coating material of LPECCU appeared excellent biodegradability in the soil. The optimal N cumulative release rate (72.49 %) of LPECCU was obtained (liquid-solid rate of 1.43, –CNO/–OH molar rate of 2, and the film formation rate of 6.66 %). The lettuce growth study was conducted to further evaluate the pot application of the LPECCU. In comparison to conventional urea, LPECCU could improve the total dry matter accumulation and N use efficiency of the lettuce. • Novel lignin/paraffin/epoxy resin composite coated urea (LPECCU) was prepared. • The release longevity of LPECCU was related to preparation of coating material. • The coating material appeared excellent biodegradability in the soil. • The LPECCU could improve the N use efficiency and growth of lettuce. [ABSTRACT FROM AUTHOR]

A convenient and efficient Ni-catalyzed reaction has been developed for synthesis of mono-substituted o -carboranes, involving cross-coupling of readily available and sterically hindered 1-bromomethyl- o -carborane with various alkyl and aryl Grignard reagents under mild conditions, and the corresponding o -carborane derivatives were obtained in good to excellent yields. This method should provide a new strategy for construction of diverse and useful functionalized boron cluster compounds for medicinal chemistry and material chemistry. [ABSTRACT FROM AUTHOR]

[Display omitted] • Draw the phase diagram of BAUR-Ⅰ. • Investigate the effects of cooling rates and urea concentrations on MSZWs. • Analyze the nucleation process by the self-consistent Nývlt-like and classical 3D models. • Explore the activation energy of BAUR-Ⅰ. As an intermediate for preparing sedative drugs, barbituric acid (BA) is often used for anesthesia and hypnosis in clinical practice. Due to the poor solubility of BA, barbituric acid – urea co-crystal (BAUR) was prepared to improve the physicochemical properties and bioavailability of BA. Notely, urea is also required in the production process of BA, so selecting urea as the co-crystal former will not bring additional impurities. BAUR has three forms reported. In this paper, the phase diagram of BAUR-Ⅰ was measured to determine the limit concentration of urea. Further, the nucleation metastable zone experiments were conducted to investigate the effects of cooling rates and urea concentrations during the nucleation. The nucleation process was then simulated using two approaches: the self-consistent Nývlt-like approach and the classical 3D model approach. Combined with the calculation of nucleation activation energy E sat , it can conclude that increasing the concentration of urea widens the metastable region to inhibit the nucleation of form Ⅰ in the cooling crystallization. [ABSTRACT FROM AUTHOR]

An advanced hydrophobic lignin-based polyurethane coated urea (HLPCU) was successfully developed by synergy of carbon black (CB) and polysiloxane. In this work, CB and polysiloxane were employed to modify the liquefied lignin-based polyurethane (LLPU) and improve it's the hydrophobicity. The effects of polysiloxane contents and coating rates on the nutrient release of HLPCU were thoroughly investigated. The lignin was degraded into polyol with a low molecular weight. FT-IR, XPS and EDX results confirmed that polysiloxane was grafted to the LLPU. The water contact angle (WCA) of the HLPUs (89.39°–98.68°) gradually increased as the polysiloxane content rose (5 %–15 %). However, when the polysiloxane content further increased to 20 %, the WCA of the HLPUs rapidly declined (90.82°). A proper amount of polysiloxane molecules could increase thermo-physical properties of LLPU. The almost no pores were observed on the section micrograph of the HLPCU obtained by synergy of CB and polysiloxane. Synergy between CB and polysiloxane could significantly improve hydrophobicity and then enhance N release longevity of HLPCU (polysiloxane content of 15 %, coating rates of 7 %) up to 44 days. Compared to traditional urea, HLPCU could improve total N use efficiency the cabbage. The HLPCU and HLPCU85 treatments (15 % weight loss with fertilization) reduced the greenhouse effect of N 2 O, CO 2 and CH 4 and finally reduced GWP, especially for HLPCU85 treatment. This work will supply an advanced approach and process technology for progress of HLPCU and sustainable agriculture. • An advanced hydrophobic lignin-based polyurethane coated urea (HLPCU) was prepared. • Synergy between carbon black and polysiloxane improved nutrient release of HLPCU. • The coating material appeared excellent biodegradability in the soil. • The HLPCU improved the N use efficiency and reduced greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

An abstract of the article "Nickel-Catalyzed Cross-Coupling of Sterically Hindered 1-Bromomethyl-o-carborane with Alkyl and Aryl Grignard Reagents" is presented.

This study involves a new series granulate Ni modified La-Al 2 O 3 (NLA) catalysts with high temperature resistant and large specific surface area for n -decane steam reforming. NLA catalysts were prepared by using a specially designed co-precipitation technique in combination with incipient wetness impregnation. Physicochemical characteristics of as-prepared catalysts were detected by using automatic adsorption instrument, X-ray diffraction (XRD), infrared spectroscopy (IR), temperature programmed reduction (H 2 -TPR), temperature programmed desorption (NH 3 -TPD), and scanning electron microscope-energy dispersive spectrometer (SEM-EDS). Significantly, the results of characterizations showed that the series NLA catalysts presented a typical mesoporous structure with a large surface area of ∼150.0 m 2 /g, and metal Ni was strongly interacted with Al 2 O 3 to generate nickel aluminate spinel structures, and the addition of La improved the thermal stability of catalysts. Based on these data, the catalytic activities over NLA catalysts were evidently heightened compared with the corresponding La-Al 2 O 3 catalyst, moreover, the 9.0 wt% NLA catalyst exhibited higher H 2 yield and showed 100% n -decane conversion at 800 °C. The valuable information indicated in this work is that based on the special characters of NLA, bimetal particles can be supported on Al 2 O 3 with different way, which should be an effective approach to maintain both catalytic activities and thermal stability. [ABSTRACT FROM AUTHOR]

An economical and facile method for high-yield production of cobalt and nitrogen co-doped carbon by employing Cobalt salicylate/1,3-dimethylurea though pre-pyrolysis in high pressure is presented. The pre-pyrolysis process helped to produce more carbon, resulting in a weight loss of only 27% after twice pyrolysis. The as-prepared Co@N-doped carbon was charactered and applied as catalyst for the carbonylation of amines to form formamides for the first time in an atomic economic method. A new strategy for synthesis of Co@N-doped carbon materials which is scalable and of high-yield provides highly efficient cost-effective catalyst for economic carbonylation of amines to form formamides. Structure of Co@NC-800 and proposed active site for carbonylation. Unlabelled Image • An economy and facile strategy for high-yield production of nitrogen and cobalt codoped nanoporous carbon. • Carbonylation of amines to form formamides were conducted by using CO with the help of none-noble metal catalyst. • Cobalt nano particles played an essential role in the reaction of carbonylation. [ABSTRACT FROM AUTHOR]