一种新型气体报警器检定操作台的研制

针对有毒有害气体报警器检定过程中存在的安全防护问题,研制了一种防毒防害型气体报警器检定操作台,该操作台主要由操作台体、透明橱窗、排风装置、转子流量计、减压阀等组成。该操作台可以提高计量检定实验室在有毒有害气体报警器检定时对环境条件的控制能力。     

基于UWP跨平台移动式可燃气体检测报警器智能检定系统的研制

将UWP(Windows通用应用平台)技术应用于可燃气体检测报警器智能检定系统的设计,研制移动式可燃气体检测报警器智能检定系统。该系统包括移动端和PC端,移动端包括委托单信息处理、检定数据处理、数据上传、XML数据管理4个模块;PC端包括上传信息读取、委托单/证书/记录生成及打印两个模块。该系统的研制实现了检定系统在手机、平板、智能检定工作台等的跨平台应用,提高了报警器的检定效率。     

标定罩使用对气体报警器检定结果的影响

为指导检定人员在气体报警器检定时对气体标定罩的正确使用,对标准罩、大罩、小罩、不带罩4种情况进行试验,并对气体报警器检定结果的绝对误差、响应时间、重复性等参数进行对比分析。结果表明,在满足绝对误差±5%FS之内、响应时间不大于60 s、重复性不大于2%的技术指标要求时,使用标准罩能够得到更准确、稳定、符合现场模拟真实数值的检定结果。该研究有利于提高气体报警器检定结果的准确性。     

可燃气体检测报警器计量检定与计量管理的探讨

指出了可燃气体检测报警器计量检定的重要性,结合河南省南阳市辖区内可燃气体检测报警器计量检定的现状,着重分析了计量检定与计量管理存在的问题和难点,并且提出了相关建议。     

有毒有害气体报警器检测探讨

介绍了常见有毒有害气体检测报警器的分类。对气体检测报警器的检测方法进行探讨,为此类报警器的检测方法提供建议。     

复合式气体报警器检定装置的研制

提出一种新型复合式气体报警器检定方法,根据此方法设计一套复合式气体检测报警器检定装置。该检定装置由工作柜、气瓶存储柜、气体输送气路、流量控制器、气体稀释装置、旋转工作台6部分组成。其中气体输送气路共有6路通道,气体稀释装置的重复性不大于0.5%。旋转工作台可同时对多台仪器进行测量,另外还配备了证书编辑软件。该装置检定结果的扩展不确定度不大于5%(k=2),其中:用于0~100%LEL CH4检定的扩展不确定度为3.0%(k=2);用于0~100μmol/mol H2S检定的扩展不确定度为5.0%(k=2);用于0~100μmol/mol CO检定的扩展不确定度为4.2%(k=2);用于0~20.9%O2检定的扩展不确定度为3.4%(k=2)。该检定装置工作效率高,采用PLC和上位机的控制方式能够实现检定过程自动化测量。该装置主要适用于CH4,H2S,CO,O2气体报警器的检定。     

可燃气体检测报警器检定用标准物质的选择

可燃气体检测报警器,亦称测爆仪,广泛应用于危险化学品场所中可燃性气体泄漏事故的检测报警,属于国家强制检定的工作用计量器具。JJG693-2004可燃气体检测报警器(以下简称报警器)国家计量检定规程(以下简称规程)经国家质量监督检验检疫总局于2004年3月2日批准,并自2004年9月2日     

呼出气体酒精含量探测器检定的注意事项

介绍呼出气体酒精含量探测器的工作原理和国家标准对使用探测器的要求,为确保探测器有效准确的量值溯源,采用呼出气体酒精含量探测器自动检测系统进行检定。该系统能够解决标准气体不易保存和定值容易发生改变的难题,同时控制吹气压力,保证探测器采样的一致性,并列举了检定操作时应注意的问题和细节。     

常用气体报警器的工作原理、性能及应用

按照常用气体报警器的分类,系统分析了每种报警器的工作原理、工作性能及应用范围,介绍了常用气体报警器在国内外的发展状况.     

标准气体在检测可燃气体报警器中的重要性

介绍可燃气体报警器的检测现状，分析可燃气体报警器检测元件中毒的原因，强调了检测可燃气体报警器时使用标准气体的重要性，以及标准气体的正确使用。     

氮中磷化氢气体标准物质的制备

用称量法配制磷化氢气体标准物质,以配制值作为标准值,研制出浓度为10~4 000μmol/mol的氮中磷化氢气体标准物质,其量值相对扩展不确定度U_(rel)=2%(k=2),其均匀性满足FF_α,稳定性满足|b_1|t_(0.95,n-2)·s(b_1)。试验测试和应用结果表明,该标准物质量值准确可靠,均匀性、稳定性和不确定度符合项目任务书的要求,可用于磷化氢气体报警器的检定、校准以及环境监测和化工企业等领域的质量控制、方法确认。     

The mechanism of copolymerization of maleic anhydride with styrene and with vinyl acetate

A nonaqueous potentiometric direct titration method was used to determine the composition diagrams for the copolymerization of maleic anhydride with styrene and with vinyl acetate in methyl ethyl ketone at 50°C. The data were analyzed using nonlinear least-squares minimization routines to fit composition equations for the terminal, penultimate, and complex models directly. The applicability of each model to both systems were evaluated statistically. The penultimate model was found to best describe both systems, although in the case of the maleic anhydride/vinyl acetate system this was only a small improvement over the terminal model. Although significant comonomer complexation occurs in both systems, the complex model did not provide statistically significant improvement in fit to the data compared with the terminal model.     

氮中丙烯腈气体标准物质的研制

以高纯丙烯腈和高纯氮气为原料,采用称量法配制氮中丙烯腈气体标准物质。对配制的气体标准物质分别进行机械混匀试验、压力均匀性和时间稳定性试验。经F检验,2.00μmol/mol及5.00μmol/mol两种浓度的样品在0.5~10 MPa范围内标准值无显著变化,具有较好的压力均匀性;在–20℃和40℃条件下保存7 d,其量值无显著变化,可满足运输环节量值稳定;在常温下贮存9个月量值无显著变化,表明其稳定性良好,满足国家二级标准物质对有效期的要求。对定值结果的不确定度进行评定。配制的氮中丙烯腈气体标准物质标准值为(2~5)×10~(–6)mol/mol,相对扩展不确定度为9%(k=2)。该标准物质达到国家二级标准物质的相关技术要求,可用于对丙烯腈气体报警器的校准。     

Vertical and directional insertion of helical peptide into lipid bilayer membrane

A novel helical hexadecapeptide carrying a poly(ethylene glycol) (PEG) chain at the N terminal was synthesized. The N and C terminals of the compound are labeled with a fluorescein isothiocyanate (FITC) group and an N-ethylcarbazolyl group (ECz), respectively. An octapeptide carrying the same groups and a hexadecapeptide without a PEG chain were also synthesized and used as control. A mixture of the peptide and dimyristoylphosphatidylcholine was sonicated in a buffer to prepare the liposome. The orientation as well as direction of the helical segment in the lipid bilayer were analyzed by quenching experiments of the FITC and the ECz fluorescence. The results clearly indicated that the helical segment of the peptide penetrated into the lipid bilayer with vertical orientation in both the gel and liquid crystalline states of the lipid bilayer. Notably, the bulky N terminal was left behind in the outer aqueous phase of liposome, meaning that the C terminal of the peptide points to the inner aqueous phase of liposome. The insertion mode of the helical peptide into a bilayer membrane is therefore well-regulated in terms of the orientation and the directionality by designing the balance between the PEG chain and the helix length. The methodology presented here will initiate a way to construct artificial functional molecular systems that can induce vectorial transport phenomena as seen in biological systems.     

A fluorometric and mitochondrion-targetable probe for rapid,naked-eye test of hypochlorite in real samples

A colorimetric, fluorometric and mitochondrion-targetable probe (Rh-ClO) based on rhodamine B fluorophore and thiophene-2-carbohydrazide has been unveiled and successfully utilized for ClO^- detection in water samples and HeLa cells.     

Scanning electrochemical mapping of spatially localized electrochemical reactions induced by surface potential gradients

The influence of a surface potential gradient on the location and extent of electrochemical reactions was examined using a scanning electrochemical microscope. A linear potential gradient was imposed on the surface of a platinum-coated indium tin oxide electrode by applying two different potential values at the edges of the electrode. The applied potentials were used to control the location and extent of several electrochemical reactions, including the oxidation of Ru(NH3)6(2+), the oxidation of H2, and the oxidation of H2 in the presence of adsorbed CO. Scanning electrochemical mapping of these reactions was achieved by probing the feedback current associated with the oxidation products. The oxidation of Ru(NH3)6(2+) occurred at locations where the applied potential was positive of the formal potential of the Ru(NH3)6(2+/3+) redox couple. The position of this reaction on the surface could be spatially translated by manipulating the terminal potentials. The rate of hydrogen oxidation on the platinum-coated electrode varied spatially in the presence of a potential gradient and correlated with the nature of the electrode surface. High oxidation rates occurred at low potentials, with decreasing rates observed as the potential increased to values where platinum oxides formed. The extent of oxide formation versus position was confirmed with in-situ ellipsometry mapping. In the presence of adsorbed carbon monoxide, a potential gradient created a localized region of high activity for hydrogen oxidation at potentials between where carbon monoxide was adsorbed and platinum oxides formed. The position of this localized region of activity could be readily translated along the surface by changing the terminal potential values. The ability to manipulate electrochemical reactions spatially on a surface has potential application in microscale analytical devices as well as in the discovery and analysis of electrocatalytic systems.     

The helix-inversion mechanism in double-stranded helical oligomers bridged by rotary cyclic boronate esters

Attracted by the numerous regulatory functions of double-helical biopolymers such as DNA, many researchers have synthesized various double-helical systems. A recently synthesized double-stranded helical oligomer covalently bridged by rotary boronate esters (BBDD) was shown to undergo helix-inversion that might serve as platform to design rotor systems. However, the detailed helix-inversion mechanism could not be investigated experimentally. Direct molecular dynamics simulations based on density-functional tight-binding energies and gradients computed on-the-fly reveal that disentanglement to the unraveled form and following exchange of the twisted terminal trimethylsilyl (TMS) groups are prerequisites for the observed helix-inversion. The potential of mean force confirms that the originally assumed “concurrent” rotation of the boronate esters and the helix-inversion involves shorter time scale “step-wise” processes, triggered by the disentanglement and exchange of the TMS groups. These results indicate that inversion dynamics of double-helical molecules such as BBDD may be controllable by chemical fine-tuning of the terminal groups. © 2019 Wiley Periodicals, Inc.     

A Double Plug–Socket System Capable of Molecular Keypad Locks through Controllable Photooxidation

Two robust divalent complexes have been successfully constructed by using complementary rigid spacers (anthracene vs. 1,4,5,8‐naphthalenediimide (NDI)) and two pairs of [24]crown‐8 ethers and secondary dialkylammonium functionalities as binding motifs. It was demonstrated that properly selected, rigid spacers are more efficient than flexible ones for achieving strong multivalent association. This is presumably due to the preorganization of the rigid spacers, the cooperation between charge‐transfer interactions of rigid spacers, and the complexation of the binding motifs. Furthermore, the intermolecular photoinduced electron transfer (PET) between rigid spacers in these robust complexes could be switched on and off by modulating their complexation through acid–base reactions, which is reminiscent of a plug–socket system capable of electron transfer. In addition, the self‐sensitized photooxidation of the divalent host with anthracene as a spacer can be completely inhibited after complexation with the divalent guests that contain NDI as spacers. This process could also be understood by invoking intermolecular PET and could be turned on and off through acid–base reactions. The photophysical and photochemical properties of these robust complexes have been interpreted as molecular keypad locks with alarm systems. Thus, a double plug–socket system and molecular keypad locks were successfully integrated inside robust multivalent systems and then the normal molecular devices were endowed with logic functions.