过氧乙酸产品相关国家标准解读

GB19104-2003、GB19105-2003、GB/T19108-2003标准是在我国发生“非典”疫情的紧急情况下,为了严格控制过氧乙酸消毒产品质量和它的包装、贮运安全以及相关的检验方法而制定的三项标准。在当时的“非典”时期,市场卫生消毒产品质量混乱的特定情况下,国家颁布实施的这三项标准,对指导过氧乙酸产品的生产,控制过氧乙酸产品质量、规范消毒产品市场经济秩序,起到了举足轻重的作用。特别是近年来各种疫情屡屡发生,过氧乙酸是控制疫情蔓延必备的消毒产品。标准的颁布与实施对生产者、经销者、消费者有着实际的指导意义和现实意义,也是目前评价…     

Simultaneous electroanalysis of peroxyacetic acid and hydrogen peroxide

The electrochemical behavior of peroxyacetic acid (PAA) in the presence of hydrogen peroxide (H2O2) has been investigated using cyclic voltammetry and hydrodynamic techniques [rotating disk electrode (RDE) voltammetry and rotating ring-disk electrode (RRDE) voltammetry]. The results have been analyzed aiming at simultaneous electroanalysis of both species. Glassy carbon and gold electrodes were used for this investigation. It was found that the reduction of PAA, as well as H2O2, is highly sensitive to the electrode material; for example, at 100 mV s-1, the reduction peak potentials of PAA were 0.2 and -1.1 V at gold and glassy carbon electrodes, respectively. The well-separated steady-state limiting currents were obtained using a gold electrode for the reduction of both PAA and H2O2 and also a well-defined one for the oxidation of H2O2. On the basis of the RDE experiments, good calibration curves were obtained for both species over a wide range of their concentrations, for PAA and H2O2 in the range of 0.36 to 110 and 0.11 to 34 mM, respectively. The simultaneous and selective electroanalysis of PAA and H2O2 in their coexistence is demonstrated for the first time.     

气载放射性碘采样测量方法研究进展

介绍气载放射性碘及其测量方法概要,气载放射性碘的采样方法、分布参数及其对测量的影响与解决方案、量值溯源方法的研究进展,着重讨论了分布参数对测量的影响及相应的解决方案。     

Simultaneous HPLC determination of peroxyacetic Acid and hydrogen peroxide

The first instrumental method for simultaneous determination of peroxyacetic acid (PAA) and hydrogen peroxide has been developed. The successive quantitative reaction of PAA with methyl p-tolyl sulfide (MTS) and hydrogen peroxide with triphenylphosphine (TPP) yields the corresponding sulfoxide MTSO and phosphine oxide TPPO. The reagents and their oxides are separated by HPLC on reversed-phase columns with acetonitrile/water gradient elution within 5 min. External calibration with the solid standards of MTSO and TPPO leads to a very accurate and reliable method. Samples are stable and can be stored after derivatization for several days prior to analysis. Real samples from brewery disinfection were analyzed in comparison to titration with excellent correlation.     

Uncertainty assessment for the airborne nanoparticle collection efficiency of a TEM grid-equipped sampling system by Monte-Carlo calculation

A mini particle sampler (MPS) equipped with a transmission electron microscopy (TEM) grid enables convenient particle sampling to subsequent analysis. However, its sampling efficiency involves uncertainties, and accurate sampling efficiency is required for particle collection applications. In this study, the sampling efficiency uncertainties from measured data and models are quantified using Monte-Carlo methods. The Sobol variance-based sensitivity analysis is used to determine the contributions of parameters to the sampling efficiency uncertainties. The results reveal that the sampling efficiency uncertainties from experimental dispersion calibration and theoretical models are generally less than 1% and 9%, respectively. Most sampling efficiency measured data are covered by the efficiency uncertainty range simulated by theoretical models. Pore size and flowrate contribute significantly to the sampling efficiency uncertainties and require control to improve the sampling efficiency precision. Besides, the Cunningham correction factor is also a sensitivity parameter. The utilization of proper models is crucial to support simulations for further process optimization. This study offers a quantitative method for nanoparticle collection efficiency analysis, which will help assess nanomaterials’ workplace exposure.     

Time-weighted average sampling with solid-phase microextraction device: implications for enhanced personal exposure monitoring to airborne pollutants

The solid-phase microextraction (SPME) device is used as a time-weighted average (TWA) sampler for gas-phase analytes by retracting the coated fiber a known distance into its needle housing during the sampling period. Unlike in conventional spot sampling with SPME, the TWA sampling approach does not allow the analytes to reach equilibrium with the fiber coating, but rather they diffuse through the opening in the needle to the location of the sorbent. The amount of analytes accumulated over time gives the measurement of the average concentration to which the device was exposed to. Depending on the sorbent used as the sink, TWA sampling for various analytes is possible with times ranging from 15 min to at least 16 h. Both the poly(dimethylsiloxane) (PDMS) and poly(dimethylsiloxane)/divinylbenzene (PDMS/DVB) fiber coating phases were tested, with the latter employing on-fiber derivatization for reactive carbonyl compounds, e.g., formaldehyde. Described herein are the theoretical and practical considerations for using the SPME device as a TWA sampler.     

A photoinduced electron-transfer reagent for peroxyacetic acid, 4-ethylthioacetylamino-7-phenylsulfonyl-2,1,3-benzoxadiazole,based on the method for predicting the fluorescence quantum yields

To develop new photoinduced electron-transfer (PET) reagents, we established a method for predicting the fluorescence quantum yields (phi) of the benzofurazan compounds bearing an aliphatic substituent group having an n-electron. The PET process occurred sufficiently to reduce the phi values in the benzofurazan compounds bearing an aliphatic moiety, which had a high quenching ability. The quenching ability was estimated by the molecular orbital calculation and Stern-Volmer plotting. The phi values of the benzofurazan compounds could be controlled by changing the quenching ability of a substituent group. We succeeded in designing a PET reagent for peroxyacetic acid (PAA), 4-ethylthioacetylamino-7-phenylsulfonyl-2,1,3-benzoxadiazole (EPB), using the established method for predicting the phi values. EPB and its oxidized derivative were separated by reversed-phase HPLC and fluorometrically detected at 479 nm with excitation at 362 nm. The attained detection limit for PAA was 105 fmol (S/N = 3) and the cross-reactivity toward hydrogen peroxide was very low, indicating EPB is a highly sensitive and selective reagent for PAA.     

The sampling interval in systematic activity sampling

This article deals with the effect of the sampling interval on the precision of systematic activity sampling, and models for medium and large sampling intervals are developed. The problem of poor precision due to possible cyclic properties of the process is also analysed, and a necessary criterion for non-interference is derived.     

Curved PVDF airborne transducer

In the application of airborne ultrasonic ranging measurement, a partially cylindrical (curved) PVDF transducer can effectively couple ultrasound into the air and generate strong sound pressure. Because of its geometrical features, the ultrasound beam angles of a curved PVDF transducer can be unsymmetrical (i.e., broad horizontally and narrow vertically). This feature is desired in some applications. In this work, a curved PVDF air transducer is investigated both theoretically and experimentally. Two resonances were observed in this transducer. They are length extensional mode and flexural bending mode. Surface vibration profiles of these two modes were measured by a laser vibrometer. It was found from the experiment that the surface vibration was not uniform along the curvature direction for both vibration modes. Theoretical calculations based on a model developed in this work confirmed the experimental results. Two displacement peaks were found in the piezoelectric active direction of PVDF film for the length extensional mode; three peaks were found for the flexural bending mode. The observed peak positions were in good agreement with the calculation results. Transient surface displacement measurements revealed that vibration peaks were in phase for the length extensional mode and out of phase for the flexural bending mode. Therefore, the length extensional mode can generate a stronger ultrasound wave than the flexural bending mode. The resonance frequencies and vibration amplitudes of the two modes strongly depend on the structure parameters as well as the material properties. For the transducer design, the theoretical model developed in this work can be used to optimize the ultrasound performance.     

Passive focus sensor

A focus-sensor module for large-format photographic cameras has been developed that permits the measurement of defocus at any location of interest in the image field. The focus sensor employs passive triangulation through a split imaging aperture. The main difference between commercial autofocus modules with fixed-measurement positions and the new module is that the imaging aperture is subdivided into more than two fields to compensate for the unknown location of the defocus measurement.

At ?/5.6 the focus sensor shows a maximum resolution in defocus of approximately 0.1mm at the image side at levels of illuminance in the recording plane ≥0.01 lx.

     

数字式机载光电伺服系统的实现

采用基于DSP和CPLD的数字化伺服控制技术解决光电传感器的机载应用问题:隔离机体的高频振动并随动于驾驶员头盔.利用TMS320LF2407的强大数字处理能力和丰富的外围接口实现伺服系统位置环、速度环和电流环的数字控制,将陀螺模拟信号经V/F转换成10 kHz～90 kHz的频率信号,采用Lattice LC4512V的10M基频对的频率信号计数成16位数字信号,实现陀螺与DSP的无缝高速连接.试验结果表明数字伺服系统达到了较高的控制精度,能满足光电传感器的机载使用要求.     

Collection and characterization of airborne nanoparticulates

This paper describes the use of a thermal precipitation device to collect representative, airborne nanoparticulates on transmission electron microscope (TEM) grid supports and their characterization using a bright field (BF)–dark field (DF)–selected area electron diffraction (SAED)–energy dispersive spectrometry (EDS) analysis protocol. Two airborne nanoparticulate regimes are illustrated and compared: (1) general nanoparticulates, composed of nanocrystalline aggregates containing from 2 to >1000 individual particles, ranging in size from approximately 1 to 100 nm and (2) complex, branched clusters of amorphous, carbonaceous spherules (containing from 50 to >1000 spherules, which range in size from 10 to 40 nm in diameter) and carbon nanocrystal aggregates containing nanotubes and other polyhedra. Commercial nanoparticulate aggregates of TiO₂ and Si₃N₄ are also observed in the context of characterization standards and the nanotechnology potential for contributing to atmospheric pollutants.     

Powder sampling

The factors involved when sampling powder mixes have been reviewed. The various methods are evaluated (manual, automatic, and sub-sampling) and the errors incurred are discussed. Certain rules have been applied to various samplers and their suitability for powder mixtures are described. The spinning riffler is apparently the most suitable, while the use of sample thieves should be avoided due to error and bias.     

Biologically driven fractionation of airborne mutagens

Abstract

A three‐level separation scheme applied in the bioassay‐directed search for major airborne mutagenic compounds on inhalable particulate matter has been employed. The biologically “hot” fractions are separated and analyzed chemically or subfractionated to isolate “hot” subfractions which are then chemically analyzed by GC/MS, GC/NCIMS, FTIR, HPLC, Fluorescence and Photodiode Array UV. The mutagenicity assay has involved TA98, TA100, TA98NR and TA98DNP strains. In essence, we are using mutagenicity as our chromatographic detector to pinpoint the most bioactive fractions and compounds in the air which are assumed to be responsible for human health impact, and then identify them as well as assess their reactivity. The comparison of winter and summer samples indicates that the profiles are similar in the two periods. However, levels of polycyclic aromatic hydrocarbons (PAH) are significantly greater in winter as compared to summer. The major mutagenic substances derived from PAH in airborne particulate matter are polar PAH derivatives and the higher contribution of these polar compounds in summer relative to winter suggests that chemical and photochemical reactions during the warm season are important.     

被动声纳的航迹关联

1引言 分布式系统中,需要将不同声纳基阵测得的目标航迹进行关联和融合.航迹关联是一个统计决策过程,即判决不同基阵测得的不同航迹是否来自同一目标源;航迹融合是在航迹量测来自同一目标的假定下,利用航迹量测进行统计滤波,以获得更好的跟踪性能.通常,二者是顺序进行的,如图1所示.航迹融合的效果很大程度上取决于航迹关联的正确与否.若航迹关联错误,随之进行的航迹融合不仅不会改善跟踪性能,反而会恶化.     

Combined double sampling and variable sampling interval X chart

In recent years several studies have shown that the X chart with variable sampling intervals (VSI), the X chart with variable size (VSS), the X chart with variable sample size and sampling intervals (VSSI) and the X chart with variable parameters (VP) detect both small and moderate shifts in the process mean more quickly than the traditional Shewhart X chart. Double sampling is the counterpart to double sampling plans. A combined double sampling variable sampling interval (DSVSI) X chart is studied in this paper. It is compared with the aforementioned charts and with the CUSUM and EWMA charts. In all cases, the DSVSI X chart is quicker at detecting small and moderate shifts in the process mean. An example is provided.