Kinetically guided high-yield and rapid production of ε-caprolactone in a microreactor system

Industrial production of ε-caprolactone, the monomer of biodegradable polycaprolactone, consists of acetic acid peroxidation and the Baeyer–Villiger oxidation of cyclohexanone in semi-batch reactors. The strong exothermic feature of the latter and ease of ε-caprolactone hydrolysis significantly affects the production efficiency. Here, collective effects of kinetic studies and density functional theory (DFT) calculations reveal activation energy of the Baeyer–Villiger oxidation is higher than that of ε-caprolactone hydrolysis and the hydrolysis barrier is controlled by hydrogen bond energy of the reaction medium. Then, we developed a microreactor system to intensify heat transfer thereby allowing safe and efficient production of ε-caprolactone. A yield of 99.6% was achieved within minutes via consecutive two-step reactions of peroxidation and the Baeyer–Villiger oxidation, as compared with state-of-the-art yield of 96% in hours of industrial operation. The high selectivity is attributed to high reaction temperature allowed by the microreactor and DFT-guided choice of solvent to mitigate the hydrolysis.     

Net primary production and nutrient cycling in an apple orchard–annual crop system in the Loess Plateau,China: a comparison of Qinguan apple,Fuji apple,corn and millet production subsystems

In this study, we investigated net primary production (NPP) and nutrient cycling in an apple orchard–annual crop system located in the Hill and Gully Region of the Loess Plateau, which included four production subsystems: Qinguan apple, Fuji apple, corn and millet. The results showed that NPP of corn (Zea mays L.) was two to three times greater than for millet (Setaria Italica L.) or apples (Malus domestica Borkh., cv ‘Fuji’ and ‘Qinguan’). Annual nutrient uptake by corn and millet was also much larger compared to apple trees. A comparison of nutrient use efficiency based on economic product showed that P and K use efficiency for Qinguan apples was about 50% greater compared to corn, while there was little difference in N use efficiency between apples and corn. More than 94% of the nutrients taken up by annual crops were lost from the system through the removal of grain and above-ground crop residue. In contrast, apple harvest and tree pruning resulted in the removal of 10–50% of the nutrients taken up annually by apple trees. Calculations indicated that farmers applied 60 times more N and 33 times more P to Qinguan apple orchards than was removed by apple harvest, but the amount of N and P fertilizer applied to corn was slightly less than the amount of N and P removed through crop harvest. In summary, the results indicated that increasing the proportion of land planted to apples and convincing farmers to leave annual crop residue in the fields would increase the sustainability of the apple orchard–annual crop system. Additional work needs to be done to determine the fate of N and P fertilizer applied to orchards as well as optimum fertilization rates for each of the four crops in the apple orchard–annual crop system.     

Effects of 15 years of manure and inorganic fertilizers on soil organic carbon fractions in a wheat-maize system in the North China Plain

Soil organic carbon (SOC) and its labile fractions are strong determinants of chemical, physical, and biological properties, and soil quality. Thus, a 15-year experiment was established to assess how diverse soil fertility management treatments for winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) cropping system affect SOC and total N (TN) concentrations in the North China Plain. The field experiment included three treatments: (1) unfertilized control (CK); (2) inorganic fertilizers (INF); and (3) farmyard manure (FYM). Concentrations of SOC, TN, and different labile SOC fractions were evaluated to 1-m depth. In comparison with INF and CK, FYM significantly increased SOC and TN concentrations in the 0–30 cm depth, and also those of dissolved organic C (DOC), microbial biomass C (MBC), hot-water extractable C (HWC), permanganate oxidizable C (KMnO₄–C), and particulate organic C (POC) in the 0–20 cm depth. Despite the higher crop yields over CK, application of INF neither increased the SOC nor the labile C fractions, suggesting that by itself INF is not a significant factor affecting SOC sequestration. Yet, POC (18.0–45.8% of SOC) and HWC (2.0–2.8%) were the most sensitive fractions affected by applications of FYM. Significantly positive correlations were observed between SOC and labile organic C fractions in the 0–20 cm depth. The data support the conclusion that, wherever feasible and practical, application of FYM is important to soil C sequestration and improving soil quality under a wheat/maize system in the North China Plain.     

Running States of China’s Iron & Steel,Nonferrous,and Building Materials Industries in 2012

Iron & Steel Industry China’s outputs of crude steel, steel products,coke and ferrous alloys in 2012 were 716.54 million tons(up 3.1%YOY),951.86 million tons(up 7.7%YOY),443.23 million tons(up 5.2%YOY) and 31.29 million tons(up 15%YOY),respectively. Statistics from the Customs     

Effects of conservation tillage,crop residue and cropping systems on changes in soil organic matter and maize–legume production: a case study in Teso District

The effects of conservation tillage, crop residue and cropping systems on the changes in soil organic matter (SOM) and overall maize–legume production were investigated in western Kenya. The experiment was a split-split plot design with three replicates with crop residue management as main plots, cropping systems as sub-plots and nutrient levels as sub-sub plots. Nitrogen was applied in each treatment at two rates (0 and 60 kg N ha⁻¹). Phosphorus was applied at 60 kg P/ha in all plots except two intercropped plots. Inorganic fertilizer (N and P) showed significant effects on yields with plots receiving 60 kg P ha⁻¹ + 60 kg N ha⁻¹ giving higher yields of 5.23 t ha⁻¹ compared to control plots whose yields were as low as 1.8 t ha⁻¹ during the third season. Crop residues had an additive effect on crop production, soil organic carbon and soil total nitrogen. Crop rotation gave higher yields hence an attractive option to farmers. Long-term studies are needed to show the effects of crop residue, cropping systems and nutrient input on sustainability of SOM and crop productivity.     

Can litter production and litter decomposition improve soil properties in the rubber plantations of different ages in Côte d’Ivoire?

Litter production and litter decomposition influence the availability of nutrients in the soil. The investigation aimed at characterizing the dynamics of leaf litter decomposition, and soil physico-chemical and biological parameters in rubber plantations of different ages. During a 12-months’ period, field studies were done in 7-, 12-, and 25-year-old rubber plantations. For measuring of litter decomposition and input from aboveground, 324 litter bags and 27 litter traps (1 m?×?1 m) were placed in 3 sampling areas per age class of rubber plantations. The soil parameters were also characterized. The results showed that the annual litter production and the amounts of organic carbon in leaves increased with the aging of the plantations. The annual decomposition constant (k) ranged from 0.0381?±?0.0040 year^?1 in the 25-year-old plantations to 0.0767?±?0.0111 year^?1 in the 7-year-old plantations. The annually decomposed litter mass varied between 2.7?±?0.3 t ha^?1 year^?1 in the 12-year-old plantations to 4.2?±?0.3 t ha^?1 year^?1 in the 25-year-old plantations. The soil of the 25-year-old plantations showed higher values of most physico-chemical and biological variables as compared to the 7-year-old plantations: annual litter production (+?32%), annual litter mass decomposed (+?11%), annual carbon (+?15%) and nitrogen (+?11%) inputs, soil organic carbon (+?52%), total nitrogen (+?32%), soil organic matter (+?52%), soil water content (+?74%), and the total density of soil invertebrates (+?121%). The results indicate an improvement of soil properties with the aging of the rubber plantations and the importance of this agricultural system for carbon sequestration.     

Isolation and Enhancement of a Homogenous in Vitro Human Hertwig’s Epithelial Root Sheath Cell Population

Hertwig’s epithelial root sheath (HERS) cells play a pivotal role during root formation of the tooth and are able to form cementum-like tissue. The aim of the present study was to establish a HERS cell line for molecular and biochemical studies using a selective digestion method. Selective digestion was performed by the application of trypsin-EDTA for 2 min, which led to the detachment of fibroblast-like-cells, with the rounded cells attached to the culture plate. The HERS cells displayed a typical cuboidal/squamous-shaped appearance. Characterization of the HERS cells using immunofluorescence staining and flow cytometry analysis showed that these cells expressed pan-cytokeratin, E-cadherin, and p63 as epithelial markers. Moreover, RT-PCR confirmed that these cells expressed epithelial-related genes, such as cytokeratin 14, E-cadherin, and ΔNp63. Additionally, HERS cells showed low expression of CD44 and CD105 with absence of CD34 and amelogenin expressions. In conclusion, HERS cells have been successfully isolated using a selective digestion method, thus enabling future studies on the roles of these cells in the formation of cementum-like tissue in vitro.     

Comparative in Vivo Assessment of Some Adverse Bioeffects of Equidimensional Gold and Silver Nanoparticles and the Attenuation of Nanosilver’s Effects with a Complex of Innocuous Bioprotectors

Stable suspensions of nanogold (NG) and nanosilver (NS) with mean particle diameter 50 and 49 nm, respectively, were prepared by laser ablation of metals in water. To assess rat’s pulmonary phagocytosis response to a single intratracheal instillation of these suspensions, we used optical, transmission electron, and semi-contact atomic force microscopy. NG and NS were also repeatedly injected intraperitoneally into rats at a dose of 10 mg/kg (0.5 mg per mL of deionized water) three times a week, up to 20 injections. A group of rats was thus injected with NS after oral administration of a “bioprotective complex” (BPC) comprised of pectin, multivitamins, some amino acids, calcium, selenium, and omega-3 PUFA. After the termination of the injections, many functional and biochemical indices and histopathological features of the spleen, kidneys and liver were evaluated for signs of toxicity, and accumulation of NG or NS in these organs was measured. From the same rats, we obtained cell suspensions of different tissues for performing the RAPD test. It was demonstrated that, although both nanometals were adversely bioactive in all respects considered in this study, NS was more noxious as compared with NG, and that the BPC tested by us attenuated both the toxicity and genotoxicity of NS.     

Fracture behavior of a melt-infiltration-processed SiC/Si composite at 900 °C in argon,air, and steam

The fracture behavior of a melt-infiltration-processed SiC/Si composite, used to mimic the matrices of industrial fiber-reinforced ceramic composites, was examined in different atmospheres and temperatures. Specimens tested in four-point bending at 900 °C in oxygen-gettered argon, dry air, or steam-rich atmospheres exhibited higher average fracture strengths than specimens tested at 25 °C. Higher mean fracture strength values were obtained for specimens tested in dry air or in a steam-rich atmosphere at 900 °C than for specimens tested in high-purity, oxygen-gettered argon at this temperature. The increased fracture strengths obtained in air and in steam-rich atmospheres coincided with increased specimen oxidation and apparent oxide filling and blunting of flaws in these composites. A transition in the location of catastrophic failure, from sites of preexisting damage created by Vickers indentations for tests in argon to other locations for tests in air or steam-rich atmospheres, was also consistent with such apparent oxide filling/blunting of indentation-induced flaws.     

Simulation of supercritical water–hydrocarbon mixing in a cylindrical tee at intermediate Reynolds number: Formulation,numerical method and laminar mixing

The objective of this work is to study the flow dynamics and mixing of supercritical water and a model hydrocarbon (n-decane), under fully miscible conditions, in a small scale cylindrical tee mixer (pipe ID = 2.4 mm), at an intermediate inlet Reynolds number of 500 using 3-D CFD simulations. A Peng–Robinson EoS with standard van der Waals mixing rules is employed to model the near-critical thermodynamics with the mixture binary interaction parameter obtained from a Predictive Peng–Robinson EoS using group contribution theory (PPR78). The n-decane stream is introduced at the colder temperature of 700 K to ensure operation above the Upper Critical Solution Temperature (UCST, 632 K) of the water n-decane system while the water stream enters at a higher temperature of 800 K. Under these conditions, the flow in the tee mixer remains laminar and steady-state is reached. Mixing occurs predominantly due to the circulating action of a counter-rotating vortex pair (CVP) in the body of the hydrocarbon jet entering from the top. This CVP is formed due to the reorientation of the streamwise vorticity pre-existing within the hydrocarbon jet as it flows down the vertical pipe of the tee junction. The advective transport is further assisted by a secondary flow of water from the bottom stream, around the hydrocarbon jet, toward the space vacated near the top of the downstream pipe section by the downward motion of the HC jet. The CVP becomes progressively weaker due to vorticity diffusion as it is advected downstream and beyond 10–12 diameter lengths downstream of the mixing joint, transport is mainly controlled by molecular diffusion. It was found that the variations of density and transport properties with temperature do not have a significant impact on the flow and mixing dynamics for a ΔT = 100 K between the two streams. Local cooling of the fluid mixture was also observed in the mixing of water and n-decane streams entering at the same temperature (initially isothermal). This cooling effect is due to the diffusion of species along a gradient in their partial enthalpy in the mixture. Such gradients in species partial enthalpies are non-zero under near-critical conditions even for initially isothermal flows due to the non-ideality of the fluid mixture under these conditions. This local heating/cooling effect at near-critical conditions could give rise to unexpected formation of phases when operating close to critical points.     

High-temperature erosion resistance and aerodynamic oxidation mechanism of multi-layer MoSi2–CrSi2–Si/SiC coated carbon/carbon composites in a wind tunnel at 1873 K

The high-temperature erosion resistance of multi-layer MoSi₂–CrSi₂–Si/SiC coated carbon/carbon (C/C) composites was investigated in a wind tunnel. To study the aerodynamic oxidation mechanism and analyze the failure of the coated C/C composites, the shear force and bending moment distribution of the tested specimens in a wind tunnel were calculated. Flexural strengths and thermogravimetric analysis of the coated specimens were measured. These results show that the multi-layer MoSi₂–CrSi₂–Si/SiC antioxidation coating can protect the C/C composites from high-temperature erosion in a wind tunnel at 1873 K for more than 86 h. Due to the high viscosity of SiO₂, the multi-layer coating lacked effective oxidation resistance from 900 to 1500 K, resulting in extensive mechanical damage and the fracture of the tested specimens.     

Comments on ‘Lattice Boltzmann simulation of alumina-water nanofluid in a square cavity’ by Yurong He,Cong Qi,Yanwei Hu,Bin Qin,Fengchen Li and Yulong Ding

This work presents some comments concerning the paper entitled ‘Lattice Boltzmann simulation of alumina-water nanofluid in a square cavity’ by Yurong He, Cong Qi, Yanwei Hu, Bin Qin, Fengchen Li and Yulong Ding which was published in Nanoscale Research Letters in 2011. The comments are related to the numerical parameters and the computed results of average Nusselt number.     

Processing and properties of Bi0.98R0.02FeO3 (R = La,Sm, Y) ceramics flash sintered at ~650°C in <5 s

We show that flash sintering produces single-phase, nanograin-sized polycrystals of isovalent-substituted multiferroic ceramics of complex compositions. Single-phase polycrystals of Bi_0.98R_0.02FeO₃ (R = La, Sm, Y) were produced at a furnace temperature of ~650°C in a few seconds by the application of an electric field of 50 V cm⁻¹, with the current limit set to 40 mA mm⁻². The dielectric and insulating properties compared favorably with expected values. Impedance spectroscopy suggests electrically homogenous microstructure, except for the sample Bi_0.98La_0.02FeO₃ that shows a small grain boundary contribution to the impedance. These results reinforce the enabling nature of flash sintering for ceramics which pose difficulties in conventional sintering because they contain low melting constituents or develop secondary phases during the sintering protocol.     

CaAl2Cr2O7: Formation,synthesis, and characterization of a new Cr(III) compound under air atmosphere in the Al2O3–CaO–Cr2O3 system

Despite huge potential, Al₂O₃–CaO–Cr₂O₃ system has been one of the least investigated one due to the generation of carcinogenic and toxic Cr(VI) compounds. Herein, we investigated the system under air atmosphere varying Cr₂O₃ while keeping Al₂O₃:CaO ratio constant in order to identify the Cr(VI) dominant region, eventually to avoid it. The Ca₄Al₆Cr^VIO₁₆ phase predominantly formed in the air atmosphere with Cr₂O₃ content up to ∼12 mol%. However, an unprecedented Cr(III) phase appeared under air at higher Cr₂O₃ content (26.43 mol%). We then synthesized the new polycrystalline ternary Cr(III) compound (CaAl₂Cr₂O₇) at 1500 °C under air atmosphere for the first time. A trigonal symmetry of hexagonal crystal family with space group P3 (143), lattice parameters a = b = 7.7909 Å and c = 7.6506 Å were determined from the X-ray powder diffraction pattern study. Electron microscope studies revealed uniform hexagonal microcrystals with similar lattice parameters. Most significantly, the binding energies of 586.1 and 576.2 eV for Cr2p_1/2 and Cr2p_3/2 respectively implied the +3 oxidation state of Cr in this compound.