硅藻土粒径和含量对PVC木塑复合材料性能的影响

考察了硅藻土粒径、添加量对PVC木塑复合材料加工性能、表面状态及力学性能的影响.结果表明,粒径越小越有利于加工,复合材料的表面状态越好,拉伸强度越高；硅藻土添加量对复合材料的性能影响较大,在5～15质量份范围内,加工性能和力学综合性能较好.     

酒中乙醇浓度国标检测方法的改进

国标GB 5009.225-2016《食品安全国家标准酒中乙醇浓度的测定》第二法为酒精计法,标准方法将制备好的试样注入100m L或200m L量筒中用分度值为0.1%vol的精密酒精计读取酒精度值,在实际实验中无法实现该操作。本文通过对该国标方法的改进,能准确、高效的完成酒精计法测定酒中乙醇浓度。     

UPLC-ESI-MS/MS for determining trans- and cis-vitamin K1 in infant formulas: method and applications

A simple and sensitive method of determining vitamin K₁ isomers (cis-and trans-forms) was developed for routine monitoring of supplemented infant formulas. The proposed method involves the applications of the lipase hydrolysis and the liquid-to-liquid extraction. After the hydrolysis and extraction procedures, the vitamin K₁-enriched extract was directly injected into the ultra-performance liquid chromatography–tandem mass spectrometry system (UPLC-MS/MS). The components were detected using electrospray ionization (ESI) in positive-ion and quantified by multiple-reaction monitoring (MRM) mode. trans-vitamin K₁ was separated from the biologically inactive cis-isomer through a C₃₀ column (4.6?×?150?mm, 3?μm), and vitamin K₁-d₇ was used as an internal standard. Calibration curves were linear over the range of 9.3–464.75?ng?ml^?1 for trans-vitamin K₁ (r ²?>?0.999) and 1.71–85.25?ng?ml^?1 for cis-vitamin K₁ (r ²?>?0.999). The limit of detection for trans- and cis-vitamin K₁ was 0.011?μg 100?g^?1 and 0.01?μg 100?g^?1. The limit of quantification was 0.037?μg 100?g^?1 and 0.031?μg 100?g^?1, respectively. The intra- and inter-batch variations (RSD%) were less than 5?%. The proposed method was applied to determine vitamin K₁ isomers in milk-based, soy-based and rice-based infant formulas, and the cis-vitamin K₁ isomer contributes to 7.05–17.21?% of the total vitamin K₁ in certain infant formulas.     

Fe/Co/C–N nanocatalysts for oxygen reduction reaction synthesized by directly pyrolyzing Fe/Co-doped polyaniline

Development of precious metal-free catalysts for oxygen reduction reaction (ORR) is of great significance for the practical application of fuel cells. In this article, we report the finding that the C–N composites containing Fe and/or Co (C–PANI, Fe/C–PANI, Co/C–PANI, and FeCo/C–PANI), produced by directly pyrolyzing the Fe- and/or Co-doped polyaniline (PANI) precursors, show efficient electroactivity for ORR both in acidic and in alkaline media. Among the prepared catalysts, Fe/C–PANI and Co/C–PANI present the most positive ORR onset potential that is 0.61 V (vs. SCE) in 0.5 mol L^?1 H₂SO₄ solution or ?0.1 V (vs. SCE) in 1 mol L^?1 NaOH solution. In addition, the Fe/C–PANI catalyst shows the largest limiting-diffusion current density for ORR both in acidic and in alkaline media. A four-electron reaction of ORR on the Fe/C–PANI and Co/C–PANI catalysts is more dominant than a two-electron reaction. Fe/C–PANI catalyst also presents good electrocatalytic activity stability for ORR both in acidic and in alkaline media.     

Influence of Multiple Bionic Unit Coupling on Sliding Wear of Laser-Processed Gray Cast Iron

In this study, in effort to improve the sliding wear resistance of gray cast iron under wet lubrication conditions, specimens with different bionic units were manufactured and modified according to bionic theory. Inspired by the structure and appearance of biological wear-resistant skin, two kinds of bionic units were processed by laser on the specimen surfaces. We investigated the wear resistance properties of the samples via indentation method and then observed the wear surface morphology of specimens and the stress distributions. The results indicated that coupling the bionic units enhanced the wear resistance of the cast iron considerably compared to the other samples. We also determined the mechanism of wear resistance improvement according to the results.     

Algorithmic approach to sonification of classical Chinese poetry

The classical Chinese poetry is a remarkable form of art in traditional Chinese character. However, it is difficult for people who are unfamiliar with ancient Chinese to experience the artistic content of the poetry. In this study, a sonification scheme, Tx2Ms (Text-to-Music), is proposed to extract the poetry features between lines in verses; moreover, dynamics and interval relations are modeled to map those features to the movement of multi-dimensional musical elements such as durations. This conversion is based on poetry intonation and acoustic analysis of the pronunciations of poems; and a stochastic compositional algorithm is created by applying a Markov chain. In addition, the best pentatonic mode for a specific poem is recommended according to the formants analysis. Therefore, the sonification of classical Chinese poetry not only provides a novel way for people to appreciate Chinese poetry but also enriches the state of mind and imagery in the delivery process, and the experiment results show that the proposed system is successfully accepted by most people.     

Conceptual modeling of cardinality constraints in social publishing

Recent years have witnessed a rise of social publishing, which is a new type of social networking service. Social publishing has certain new features that call for a new way of managing and providing a large volume of documents. A fine data model is expected to evolve dynamically with the up‐to‐date knowledge, especially the associations that emerge in the context of social publishing. This paper first presents a conceptual schema of social publishing, which evolves to combine the association knowledge that reflects hidden associations in the data. A major constraint of concern is cardinality constraint. During the process of enriching a schema, the constraints to be specified should conform to the existing ones. A set of inference rules is presented for modeling with cardinality constraints. The rules are proven to be sound and complete, which helps to derive cardinality constraints from existing ones. The derived cardinality constraints are also proven to be consistent. © 2012 Wiley Periodicals, Inc.     

Exergy analysis of incremental sheet forming

Research in the last 15 years has led to die-less incremental forming processes that are close to realization in an industrial setup. Whereas many studies have been carried out with the intention of investigating technical abilities and economic consequences, the ecological impact of incremental sheet forming (ISF) has not been studied so far. Using the concept of exergy analysis, two ISF technologies, namely single sided and double sided incremental forming, are investigated and compared to conventional forming and hydroforming. A second exergy analysis is carried out with the purpose of examining the environmental impact of different forming technologies from a supply chain perspective. Therefore, related upstream activities (die set production, aluminum sheet production and energy conversion and supply) are included into the exergy analysis. The entire supply chain is modeled with Matlab/Simulink. The results of both analyses suggest that ISF is environmentally advantageous for prototyping and small production runs.     

Quantum dots trigger hot-start effects for pfu-based polymerase chain reaction

Hot-start (HS) effects were investigated in pfu-based polymerase chain reaction (PCR), when water-soluble CdTe quantum dots (QDs) were introduced in the PCR system. The HS effects were demonstrated by the higher amplicon yields and excellent suppression of non-specific amplification after pre-incubation of PCR mix with QDs between 35°C and 56°C. DNA targets were well amplified even after PCR mixture was pre-incubated 1?h at 50°C. Importantly, the effects of QDs nanoparticles could be reversed by increasing the pfu polymerase concentration, suggesting that there was an interaction between QDs and pfu DNA polymerase. Moreover, control experiment indicated that HS effect is not primarily due to the reduced pfu polymerase concentration resulted from the above interaction. Fluorescence correlation spectroscopy (FCS), a single molecule detection method, was used to investigate the possible mechanism of HS PCR with QDs. Preliminary FCS results suggested that CdTe QDs may directly interact with pfu DNA polymerase, rather than other components in the PCR system. Furthermore, results demonstrated that the interaction between QDs and pfu resulted in a reduction in pfu polymerase concentration. This study provided a good start to investigate potential implications of QDs in other key molecular biology techniques.     

集输管道绝缘接头强度评价方法研究

绝缘接头作为阴极保护系统的关键组件,其安全性与可靠性的研究在不断深入。由于集输系统高温、高压的特点,绝缘接头必然承受由于内压和热胀等导致的弯矩,加之其结构特点,可能会引起泄漏。为此,有必要综合考虑工况条件,研究绝缘接头可承受的安全弯矩值,并形成基于强度的评价方法。根据规范要求,结合管道强度理论,推导了绝缘接头承受弯矩范围的计算公式,提出了对应的绝缘接头强度校核与设计弯矩值选取方法;研究成果为绝缘接头安全设计与强度校核提供了参考与借鉴。