Research on quality improvement of the cross section cut by abrasive water jet based on secondary cutting

A manufacturing system comprises production processes and building services, both of which are supplied by different energy carriers as well as raw materials and water. These resources interact according to complex relationships and are converted into products for sale and waste flows. Holistic resource accounting allows the analyst to consider the dynamic relationships between these components, including the strong interdependence between energy and water, which has been called the energy-water nexus. Exergy analysis is a method that accounts for mass and both the quantity and quality of energy, while allowing analysis on a common basis, and for this reason, it is used increasingly to analyse resource consumption in manufacturing systems; however, it has rarely been used to consider water flows alongside energy and material flows. The main contribution of this paper is the presentation of modelling water flows in terms of exergy in the context of sustainable manufacturing. Using this technique in combination with previously developed exergy-based methods, the result is a truly holistic resource accounting method for factories based on exergy analysis that incorporates water flows. The method is illustrated using a case study of a food factory in which a 4.1% reduction in resource use is shown to be possible by employing anaerobic digester in an effluent water treatment process. The benefits of this technology option would have been underestimated compared to the benefits of waste heat capture if an analysis based on mass and energy balances alone had been used. The scientific value of this paper is the demonstration of the relatively high exergy content of effluent flows, which should therefore be regarded as potentially valuable resources. The analytical method presented is therefore of value to a wide range of industries beyond the food industry.     

TiB2 Powders Synthesis by Borothermal Reduction in TiO2 Under Vacuum

TiB₂ powders were synthesized by borothermal reduction in nanoscale TiO₂ with boron under vacuum. Reaction processes were investigated, and the effect of by‐product B₂O₃ was evaluated. Results showed that TiO₂ was firstly reduced by boron to form TiBO₃ and Ti₂O₃, and then to produce TiB₂ and B₂O₃ with increasing temperature. The reaction processes of TiB₂ powders synthesis included two‐step reduction in TiO₂ by boron and the removal of B₂O₃. The presence of B₂O₃, which was previously reported as the most important factor in promoting the coarsening of ZrB₂ and HfB₂ powders by borothermal reduction, did not lead to significant coarsening of TiB₂ powders. Due to the minor effect of B₂O₃, TiB₂ powders with small particle size and low oxygen content could be prepared by direct heat treatment of TiO₂ and boron at 1550°C under vacuum for 1 h. The particle size and oxygen content of synthesized TiB₂ powders were ~0.9 μm and ~1.7 wt%, respectively.     

A polyurethane-based elastomeric nanocomposite with a high dielectric constant

To increase the electric energy density of dielectric elastomer substantially, high dielectric constant nanocomposites were developed using polyurethane (PU) as matrix and copper phthalocyanine oligomer (CuPc)—a high dielectric constant organic semiconductor—as filler. Transmission electron microscope (TEM)-observed morphologies revealed that the sizes of CuPc particles in nanocomposite of PU chemically attached with 8.78 vol% of CuPc were in the range of 10–20 nm, much smaller than the sizes (250–600 nm) in the physical blend of PU with the same volume fraction of CuPc. At 100 Hz, the nanocomposite film exhibited a dielectric constant of 391, representing more than 60-fold increase with respect to the pure PU. The enhanced dielectric response of the nanocomposite makes it possible to induce a high electromechanical response under a much reduced electric field (a strain of 17.7 % was achieved under a field of 10 V/μm).     

On the Validity of the Poisson Assumption in Sampling Nanometer-Sized Aerosols

For a constant aerosol concentration, it is traditionally assumed that a Poisson process describes the behavior of particle detections during sampling and consequently fluctuations in the measured concentration. Recent studies, however, have shown that sampling of micrometer-sized aerosols has non-Poissonian behavior with positive correlations. The validity of the Poisson assumption for nanometer-sized aerosols has not been established and thus was tested in this study. Its validity was tested for four particle sizes—10 nm, 25 nm, 50 nm, and 100 nm—by sampling from indoor air with a differential mobility analyzer-condensation particle counter (DMA-CPC) setup to obtain a time series of particle counts. Five metrics were calculated from the data: pair-correlation function (PCF), scaled clustering index (SCI), coefficient of variation, probability of measuring a concentration at least 25% greater than average, and posterior distributions from Bayesian inference. To identify departures from Poissonian behavior, these metrics were also calculated for 1000 computer-generated Poisson time series with the same mean as the experimental data. For most comparisons, the experimental data fell within the range of 80% of the Poisson-simulation values. Essentially, the metrics for the experimental data were mostly indistinguishable from a simulated Poisson process. The greater influence of Brownian motion for nanometer-sized aerosols may explain the Poissonian behavior observed for smaller aerosols. Although the Poisson assumption was found to be reasonable in this study it must be carefully applied, as the results here do not definitively prove applicability in all sampling situations.

Copyright 2014 American Association for Aerosol Research     

矿山地质环境保护与治理现状和对策

文章详细阐述了矿山地质环境保护与治理过程中存在的问题,并依照实际情况,从制度、技术、资金等方面出发,提出了客观实际和可操作性强的对策,为实现经济社会可持续发展提供理论指导。     

Features of liquid hydrocarbon and biomarker maturity ratios during HTHP semi-open system pyrolysis of type II and III source rocks

In order to study the liquid hydrocarbon generated by laboratory pyrolysis and the biomarker maturity ratios in expelled oil with the increasing simulation temperature, the Hydrous semi-open system high temperature high pressure (HTHP) pyrolysis experiments was performed on Type II and III source rocks from 350°C to 540°C. The results showed that expelled oil yields in both samples have a trend of increased first and then decreased with the increasing temperature, while an opposite tendency occurred in the residual oil. The biomarker maturity ratios, such as ∑C_21?/∑C₂₂₊ ratio in n-alkanes, Pr/Ph ratio in isoprenoid alkenes, Ts/Tm in terpenes, and C₂₉ββ/(αα + ββ) ratios in steranes are all better indicators in terms of maturity in pyrolysis. However, the maturity biomarkers ratios interpreted by the mechanism of isomerization such as C₃₁-homohopanes 22S/(22S?+?22R) and ααα C₂₉-sterane 20S/(20S + 20R), which had already reached their equilibrium values, indicating that microbiological deterioration is one reason for the failure indicative function of αααC₂₉sterane20S/(20S + 20R) ratio. This research may also play an important role in the studies about the evolution of sedimentary organic matters in geology.     

Assembly of Enantioenriched cis‐3a,8a‐Hexahydropyrrolo[2,3‐b]indole Scaffolds by Silver(I)‐Catalyzed Asymmetric Domino Reaction of Isocyanoacetates in the Presence of Cinchona‐Derived Chiral Phosphorus Ligands

By using Cinchona‐derived chiral phosphines as catalytic ligands, enantioenriched cis‐3a,8a‐hexahydropyrrolo[2,3‐b]indoles (ent‐HPIs), which are core scaffolds in a large array of biologically active natural products, can be convergently assembled under mild conditions through the silver(I)‐catalyzed asymmetric domino reaction of readily available isocyanoacetates and 2‐(2‐aminophenyl)acrylates. Various functionalities can be tolerated in the reaction, affording enantioenriched HPIs in high overall yields and good enantioselectivities (up to 92% ees).

     

Palladium and Copper Cocatalyzed Intermolecular Cyclization Reaction: Synthesis of 5‐Aminopyrazole Derivatives

A novel and efficient palladium and copper co‐catalyzed intermolecular cyclization of acetonitriles with hydrazones has been developed for the synthesis of 5‐aminopyrazoles through C C and C N bond formation. The reaction has the advantages of easily available starting materials, simple manipulation and mild reaction conditions. The reaction involving various substituted acetonitriles and hydrazones proceeds smoothly and 5‐aminopyrazoles are synthesized in good yields. In contrast to the aliphatic and heteroaromatic substrates, the aromatic substrates tend to have a higher degree of reactivity.

     

Synthesis of [60]Fullerene‐Fused Tetralones via Palladium‐ Catalyzed Ketone‐Directed sp2 C?H Activation and sp3 C?H Functionalization

The palladium‐catalyzed ketone‐directed dual sp² C H activation and sp³ C H functionalization has been applied for fullerene functionalization for the first time. The sec‐alkyl aryl ketones have been exploited to react with [60]fullerene (C₆₀) to provide the novel and scarce C₆₀‐fused tetralones. The combined use of a highly active cationic palladium(II) catalyst and trifluoromethanesulfonic acid is crucial for the improvement of the reaction yield. A plausible reaction mechanism leading to the observed products has been proposed, and the electrochemistry of the fullerene products has also been investigated.