Classification of monovarietal Argentinean white wines by their elemental profile

The possibility of acquire a chemometric model to classify Argentinean white wines according to their provenance through elemental profile was assessed. A simple method for multielement determination in wines by inductively coupled plasma mass spectrometry along with chemometric pattern-recognition techniques is proposed. A total of 57 white wine samples of the main varieties from four winegrowing regions of Argentina: Mendoza, Rio Negro, San Juan, and Salta, were evaluated. The results of principal component analysis explained 95.95% of the variance data total. Linear discriminant analysis allowed correct discrimination according to the four geographical regions evaluated, using only five ultratrace elements (Ba, As, Pb, Mo, and Co). Discrimination rates higher than 96% for prediction and validation data sets were reached. The outcomes emphasize the skillfulness of ICPMS elemental determination in combination with chemometrics, for classification of white wine and show that could be a trustworthy technique to validate the geographical origin, authenticity and quality control of wines.     

二乙基三胺五乙酸浸取-电感耦合等离子体质谱法测定石灰性土壤中有效态铜锌铁锰

采用二乙基三胺五乙酸(DTPA)浸提石灰性土壤样品中有效态Cu、Zn、Fe、Mn后,样品溶液基体盐分较大,此时若直接采用电感耦合等离子体质谱法(ICP-MS)进行测定,极易使仪器的采样锥和截取锥发生堵塞,雾室和炬管积盐,进而影响测定准确性。据此,实验用DTPA浸提样品后,采用对样品溶液稀释10~30倍和在标准溶液系列中加入DTPA溶液进行基体匹配的方法以消除基体干扰,利用氦碰撞模式进行测定以消除多原子离子⁴⁰Ar¹⁶O对⁵⁶Fe的质谱干扰,最终实现了ICP-MS对石灰性土壤中有效态Cu、Zn、Fe、Mn的测定。对氦气流量进行了优化,并确定氦气流量为4.5mL/min。在优化的实验条件下,Cu、Zn的质量浓度为5~200ng/mL、Fe的质量浓度为100~3000ng/mL、Mn的质量浓度为30~1000ng/mL时,各元素质量浓度分别与其计数值呈线性关系,相关系数均不小于0.9998。方法检出限为0.003~0.01mg/kg。按照实验方法测定土壤有效态成分分析标准物质中的有效态Cu、Zn、Fe、Mn,测定值与认定值一致,相对标准偏差(RSD)为1.3%~3.1%。采用实验方法和标准方法HJ 804—2016(电感耦合等离子体原子发射光谱法)进行方法对照试验,二者测定值基本一致。     

Influence of low-vacuum helium cold plasma pre-treatment on the rooting and root growth of zoysiagrass (Zoysia Willd.) stolon cuttings

The influence of low-vacuum helium cold plasma treatment on the rooting percentage, root growth and physiochemical properties of zoysiagrass stolon cuttings was studied. Zoysiagrass stolon cuttings were pre-treated with 0, 100, 200, 300 and 400 W of cold plasma for 15 s. The cold plasma positively stimulated rooting and improved the root growth of the zoysiagrass stolon cuttings, and the 300 W treatment produced the best effect. The rooting percentage and root growth parameters, including the root length, total root surface area, total root volume, average root diameter, and root dry weight, significantly improved in response to the cold plasma treatment. In addition, the water uptake and relative conductivity of the stolon cuttings increased significantly in response to the cold plasma treatment. The results revealed that cold plasma-stimulated rooting and root growth appear to be a consequence of the improvement in permeability and water absorbing capacity of zoysiagrass stolon cuttings. The results of the present study will provide inspiration and support for the application of cold plasma in the vegetative propagation of plants.     

Reduced chemistries with the Quantemol database (QDB)

Typical feed gas mixtures used in technological and other plasmas may give rise to reaction networks involving several hundred reactions. Such chemistries are often too large to be used in full reactor simulations and it is therefore desirable to construct reduced chemistry networks which mimic as closely as possible the behavior of the full chemistry but employ far fewer individual reactions and species. Constructed chemistries are available from the Quantemol database (QDB) and two approaches to constructing reduced chemistry from these chemistries based on (a) physical intuition and (b) sensitivity analysis of dominant reaction pathways, are explored. In doing this it is necessary to consider different pressure and power regimes. Reduced chemistry sets are presented for CF₄ /O₂/N₂/H₂, for which 396 reactions and 52 species are reduced to 71 reactions and 26 species, and for pure O₂, for which 45 reactions and 10 species are reduced to 34 reactions.     

High-entropy alloys fabricated via powder metallurgy. A critical review

High-entropy alloys (HEAs) have attracted a great deal of interest over the last 14 years. One reason for this level of interest is related to these alloys breaking the alloying principles that have been applied for many centuries. Thus, HEAs usually possess a single phase (contrary to expectations according to the composition of the alloy) and exhibit a high level of performance in different properties related to many developing areas in industry. Despite this significant interest, most HEAs have been developed via ingot metallurgy. More recently, powder metallurgy (PM) has appeared as an interesting alternative for further developing this family of alloys to possibly widen the field of nanostructures in HEAs and improve some capabilities of these alloys. In this paper, PM methods applied to HEAs are reviewed, and some possible ways to develop the use of powders as raw materials are introduced.     

电感耦合等离子体质谱法测定锡铅焊料中11种杂质元素

锡铅焊料中的杂质元素对焊点的抗氧化性、润湿性、扩展面积有重要影响,因此对其进行测定意义重大。采用硝酸、氢氟酸溶解样品,选择H₂动态反应池模式测定Fe,标准模式测定Al、P、Cu、Zn、As、Cd、Ag、Sb、Au、Bi,同时以Sc校正Al、P、Fe、Cu,以Cs校正Zn、As、Ag、Cd,以Tl校正Sb、Au、Bi,实现了电感耦合等离子体质谱法(ICP-MS)对锡铅焊料中这11种杂质元素含量的测定。在优化的实验条件下,11种杂质元素校准曲线的相关系数均大于0.999,方法的检出限在0.002~0.80μg/g范围内,测定下限在0.007~2.73μg/g范围内。用建立的实验方法测定锡铅焊料样品中Al、P、Fe、Cu、Zn、As、Cd、Ag、Sb、Au、Bi,平行测定11次结果的相对标准偏差(RSD)为0.85%~3.5%,加标回收率为90%~110%。将实验方法应用于锡铅焊料标准物质YT9302中Al、Fe、Cu、Zn、As、Sb、Bi共7种杂质元素的测定,结果与认定值一致。     

Fabrication and mechanical properties of Al2O3–TiC ceramic composites synergistically reinforced with multi-walled carbon nanotubes and graphene nanoplates

In this study, Al₂O₃–TiC composites synergistically reinforced with multi-walled carbon nanotubes (MWCNTs) and graphene nanoplates (GNPs) were prepared via spark plasma sintering (SPS). The effects of the MWCNT and GNP contents on the phase composition, mechanical properties, fracture mode, and toughening mechanism of the composites were systematically investigated. The experimental results indicated that the composite grains became more refined with the addition of MWCNTs and GNPs. The nanocomposites presented high compactness and excellent mechanical properties. The composite with 0.8 wt% MWCNTs and 0.2 wt% GNPs presented the best properties of all analysed specimens, and its relative density, hardness, and fracture toughness were 97.3%, 18.38 ± 0.6 GPa, and 9.40 ± 1.6 MPa m^1/2, respectively. The crack deflection, bridging, branching, and drawing effects of MWCNTs and GNPs were the main toughening mechanisms of Al₂O₃–TiC composites synergistically reinforced with MWCNTs and GNPs.     

H13钢等离子堆焊Ni60A/Cr3C2覆层的磨损及热疲劳性能

采用等离子堆焊技术在H13钢基体表面上制备了Ni60A/Cr₃C₂堆焊覆层,研究了覆层的磨损行为和热疲劳性能。在600 ℃下销盘试验的结果表明,镍基碳化铬复合覆层的耐磨性是Ni60A堆焊覆层的2.8倍和基材H13钢的11.6倍。镍基覆层可以显著降低H13钢的摩擦因数,加入碳化铬则会削弱覆层的摩擦性能。随着磨损的进行,主要磨损机理从氧化磨损演变为磨粒磨损和粘着磨损。在800 ℃到室温下的热疲劳测试结果表明,镍基碳化铬复合覆层在48个热循环后疲劳裂纹达到200 μm,早于镍基覆层的62次。这说明高温氧化促进热疲劳裂纹的产生。碳化铬增强相从镍基上剥离,导致镍基复合覆层热疲劳性能下降。     

一种轻小型四极杆质谱仪射频电源的研制

四极杆结构是四极杆质谱仪的核心结构，由射频电源分别施加两组高压高频信号进行驱动，利用电场的变化和输入离子的质荷比差异对离子进行筛选。针对四极杆质谱仪小型化的研制需求，以信号调制模块、放大模块、反馈电路和直流模块为基本构型，设计了一种应用于轻小型四极杆质谱仪的射频驱动电源。经实际测试，该电源可以在谐振频率1.33 MHz、扫描频率10 Hz的输入条件下，输出峰 峰值电压最高可达3.33 kV的调幅射频高压信号并驱动四极杆结构，扫描切换时间不高于1 ms。射频电源输出信号稳定、波动小、交直比的波动为0.1%。该射频电源相较于常规的四极杆射频电源具有更高的扫描范围，体积小巧，功耗仅30 W，接口简单，有较高的实用价值。     

Co-reinforcing of ZrB2–SiC ceramics with optimized ZrC to Cf ratio

Characteristics of ZrB₂–SiC ultrahigh temperature ceramic matrix composites (UHTCMCs) reinforced with ZrC and carbon fiber (C_f) were investigated in this article. Spark plasma sintering (SPS) process was utilized to fabricate the samples at 1800 °C for 5 min under 30 MPa punch pressure and vacuumed atmosphere. In all samples, the volume ratio of ZrB₂: SiC was equal to 4:1, and the summation of ZrC and C_f reinforcements was 7.5 vol% with different ZrC: C_f ratios. Field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), densitometry, flexural strength, and hardness measurements were employed for characterization of the prepared samples. Microstructural inspection revealed the formation of SiC sheath around the carbon fibers due to several reactions in the surface SiO₂ layers existed on the SiC particles. Optimal flexural strength (628.4 MPa) and hardness (20.8 GPa) values were achieved for the sample co-reinforced with 6.5 vol% ZrC and 1 vol% C_f, with a relative density of 97.7%.