A dotted nanowire arrayed by 5 nm sized palladium and nickel composite nanopaticles showing significant electrocatalytic activity towards ethanol oxidation reaction (EOR)

To the best of our knowledge, this is the first time to report the preparation of a dotted nanowire arrayed by 5 nm sized palladium and nickel composite nanoparticles (denoted as Pd_xNi_y NPs) via a hydrothermal method using NU and PdO·H₂O as the starting materials. The samples prepared at the mass ratio of NU to PdO·H₂O 1:1, 1:2 and 2:1 were, respectively, nominated as catalyst c₁, c₂ and c₃. The chemical compositions of all synthesized catalysts were mainly studied by using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), revealing that metallic Ni was one main component of all prepared catalysts. Surprisingly, the main diffraction peaks appearing in the XRD patterns of all prepared catalysts were assigned to the metallic Ni rather than the metallic Pd. Very interestingly, as indicated by the TEM images, a large number of dotted nanowires arrayed by numerous equidistant 5 nm sized nanoparticles were distinctly exhibited in catalyst c₁. More importantly, when being used as electrocatalysts for EOR, all prepared catalysts exhibited an evident electrocatalytic activity towards EOR. In the cyclic voltammetry (CV) test, the peak current density of the forward peak of EOR on catalyst c₁ measured at 50 mV s^?1 was as high as 56.1 mA cm^?2, being almost 9 times higher than that of EOR on catalyst c₃ (6.3 mA cm^?2). Particularly, the polarized current density of EOR on catalyst c₁ at 3600 s, as indicated by the chronoamperometry (CA) experiment, was still maintained to be around 1.47 mA cm^?2, a value higher than the latest reported data of 1.3 mA cm^?2 (measured on the pure Pd/C electrode). Presenting a novel method to prepare dotted nanowires arranged by 5 nm sized nanoparticles and showing the significant eletrocatalytic activities of the newly prepared dotted nanowires towards EOR were the major contributions of this preliminary work.     

烟道流量计量标准装置

为了解决我国烟道流量计的量值溯源问题,中国计量科学研究院建立了烟道流量计量标准装置。装置使用可溯源至标准转盘的激光多普勒测速仪作为原级标准器,采用激光多普勒流速剖面扫描和超声流量计波动修正的方式测量标准流量,经校准的8声道超声流量计为工作级标准表,具备了908~104840m3/h的测量能力,扩展不确定度为0.62%(k=2),可对最大口径为1m的流量计进行校准。装置下游测试段包括圆形管段和矩形管段,能够开展烟道流量计测量性能的研究。     

Simulation Method of Dynamic Characteristics of Turbine Flow Sensor

Computational Fluid Dynamics (CFD) simulation is one of the important methods to study the performance and in-fluencing factors of turbine flow sensors. According to the working characteristics of the turbine flow sensor, the passive simulation method based on the six degrees of freedom (6-DOF) model and dynamic mesh is proposed in this paper. The reliability of the simulation method is verified by steady-state experiments and unsteady-state experiments. The results show that the trend of meter factor with flow rate acquired from the simulation is close to the experimental results, and the deviation between the simulation result and the experiment result is low with a maximum deviation of 2.88%. In the unsteady simulation study, the impeller speed changes with the inlet velocity of the turbine flow sensor, which has a good follow-up. The passive simulation method can be used to predict the dynamic performance of the turbine flow sensor.     

基于阈值和极端随机树的实时跌倒检测方法

针对基于可穿戴设备的跌倒检测存在的实时性与准确性无法兼得的问题,提出一种阈值和极端随机树融合的实时跌倒检测方法。在该方法中,可穿戴设备只需计算阈值量,无需确保跌倒检测的准确率,从而减少了计算量;同时,上位机利用极端随机树算法确保了跌倒检测的准确率。可穿戴设备通过阈值的方法过滤了大部分日常动作,因此减少了上位机检测的动作数据量。这样一来所提方法既满足了跌倒检测的高准确率,又满足了实时性。另外,为了降低跌倒检测的假阳性率,可穿戴设备融合了姿态角度传感器和压力传感器,上位机中加入了反馈机制。当检测结果出现假阳性时,通过上位机将检测错误的样本加入非跌倒数据集中进行再训练,模型经过这样的不断学习会生成适合个人的报警模型,且这种反馈机制为降低跌倒检测的假阳性率提供了新思路。实验结果表明,在1 259个测试样本中,所提方法具有平均99.7%的准确率,最低0.08%的假阳性率。     

新型均速管涡街流量传感器的测量特性研究

本文提出了新型均速管涡街流量传感器,实现差压与频率信号的双参数测量,并根据涡街信号的不同采集方式分为压 电式和差压式两种类型。 对两种一体化流量传感器的结构、原理以及信号采集方式进行了设计和阐述,并对其测量特性进行对 比分析。 结果表明,采用差压式流量传感器与经验小波变换(EWT)相结合,能将量程比由 10:1 拓宽至 140:1。 单相气最大测 量误差绝对值由 1. 46%减小至 0. 49%,重复性由 0. 17%降至 0. 05%,水流量最大测量误差绝对值也实现了从 1. 00%下降至 0. 49%,重复性低于 0. 07%。 与压电式流量传感器相比,差压式均速管涡街流量传感器在测量精度及测量范围中具有一定的应 用优势,为湿蒸汽测量提供了一种新思路。     

Macaroon-like FeCo2O4 modified activated carbon anode for enhancing power generation in direct glucose fuel cell

Macaroon-like FeCo₂O₄ nanomaterial was prepared and used as electrocatalyst in direct glucose alkaline fuel cell (DGAFC), which exhibited high catalytic activity towards glucose oxidation reaction. Maximum power density of 35.91 W m⁻² was achieved in the DGAFC equipped with a FeCo₂O₄ modified activated carbon (AC) anode, which was almost 151% higher than the control. Physical and electrochemical characterizations were performed to provide further understanding of the origin of its high activity. Our results show that the introduction of FeCo₂O₄ into the AC anode remarkably increase the exchange current density and reduce the charge transfer resistance. It is supposed that there is a synergistic effect between Fe (III) and Co (III), which accelerates electron transfer from glucose to external circuits. This study will promote the development of cost effective and environmentally benign catalysts for electrochemical energy applications.     

High hydrostatic pressure treatment as an alternative to pasteurization to maintain bioactive compound content and texture in red sweet pepper

Red sweet peppers (Capsicum annuum) are an excellent source of essential nutrients and bioactive compounds. High hydrostatic pressures (HHP) not only increase shelf-life but also maintain nutritional and organoleptic properties better in a number of food products. The aim of this work was to measure the effect of HHP and a thermal treatment, pasteurization (PA) in a water bath at 70 °C for 10 min, on some bioactive compounds (fibre, carotenoids and antioxidant activity) and on the texture (TPA; firmness and shear force) of red Lamuyo-type sweet peppers, in order to discover the relationship between treatment (HHP and PA), tissue microstructure and bioactive compound extractability. The results show that HHP at 500 MPa and PA treatments had less impact on the microstructure, bioactive compound content (fibre and antioxidant activity) and texture of red sweet peppers, than when low pressures were used. Consequently, new functional foods could be developed using red sweet pepper tissues treated with high pressures (500 MPa) and/or PA.Industrial relevanceToday’s consumers demand foods that are rich in bioactive compounds with beneficial health effects and safer, more natural, minimally-processed food products. Red sweet peppers (Capsicum annuum) are an excellent source of essential nutrients and bioactive compounds such as carotenoids and fibre. High hydrostatic pressure (HHP) processing is considered one of the most economically viable of the non-thermal technologies that helps to preserve red sweet peppers with high nutritional and quality parameters. Therefore, it would be interesting to study the microstructure of HHP-treated red sweet pepper tissues in order to discover whether this treatment promotes the extractability of bioactive compounds, and to compare the results with those obtained by pasteurizing the red sweet pepper. Thus, these enhanced red sweet peppers could be used as ingredients in the formulation of new functional foods.     

Preparation of a composite monolith with functional graphene oxide and its application in the online enrichment of ursolic acid in medicinal plant

In this study, a composite poly(functional graphene oxide-co-N-isopropylacrylamide-co-trimethylolpropane triacrylate-co-ethylene dimethacrylate) (poly(f-GO-co-NIPAAm-co-TMPTA-co-EDMA)) monolith was prepared, in which f-GO was added. The obtained monolith was characterized by nitrogen adsorption–desorption isotherm and scanning electron microscopy. The monolith exhibited a homogeneous and continuous structure, good permeability, and large surface area. The composite monolith was used as solid-phase extraction absorbent in conjunction with high-performance liquid chromatography for enrichment of ursolic acid. The calibration equation was y = 73.3980x + 0.2555, and the linear regression coefficient was 0.9987; The calibration curve was ranged from 1 to 700 μg ml⁻¹; The limit of detection and limit of quantification values were 0.3 and 1.0 μg ml⁻¹, respectively; The intraday and interday precisions were less than 2.6 and 7.4%, respectively. The recovery was in the range of 84.44–111.76%. Moreover, the adsorption amount of ursolic acid on the composite monolith was compared with the monolith without f-GO added and silica gel-C18 adsorbent. The results showed that the composite monolithic column was feasible to be used as an online SPE absorbent, which exhibiting low back pressure, good permeability, and high adsorption capacity. In addition, this method provided the possibility to extract and analyze trace components from medicinal plants.     

Effects of geometry and position of the metal delivery tube on ultrasonic gas atomization

The effects of the geometry and the position of the metal delivery tube on the pressure condition in the gas-metal interaction zone were studied. The measurements were performed under conditions which simulated ultrasonic gas atomization experiments, but at low gas atomization pressures (50–200 psig, 345–1380 kPa). Low gas atomization pressures are used in spray atomization and deposition processes such as liquid dynamic compaction (LDC), and Osprey. Depending on the experimental conditions, either underpressure or overpressure in the metal delivery tube was detected. The magnitude of the underpressures and overpressures was found to increase with the gas atomization pressure; the maximum pressure differences with respect to the atomization tank pressure were about 3 psi (21 kPa) when argon was used as an atomization gas with a pressure of 200 psig (1380 kPa). Underpressure or overpressure effects of such magnitude have a large effect on the metal flow rate during gas atomization. The large pressure differences measured in the present work result from using an atomizer with gas jet diameters larger than those used in previous investigations. Using a large ultrasonic atomizer, argon gas flow rates of about 5 kg/min can be obtained for atomization pressures of 200 psig (1380 kPa).     

高效液相色谱法测定竹筷中噻苯咪唑、邻苯基苯酚和联苯

建立高效液相色谱测定竹筷中噻苯咪唑、邻苯基苯酚、联苯的方法。以甲醇为提取溶剂,用索氏提取法提取竹筷中噻苯咪唑、邻苯基苯酚和联苯3种保鲜剂。以甲醇-水(体积比70:30)为流动相,流速1.0mL/min,采用C18柱(250mm×4.6mm,5μm)分离,紫外检测器检测,检测波长247nm,进样量20μL。方法的相关系数均大于0.999,最低检出限为0.01μg/mL,平均回收率为95.8%～97.1%,相对标准偏差为1.4%～2.6%。应用所建立的方法测定一次性竹筷中噻苯咪唑、邻苯基苯酚、联苯的残留量,结果表明：该方法样品处理简单,色谱分离完全,结果准确可靠,适于竹筷中噻苯咪唑、邻苯基苯酚和联苯的分析检测。