From ensemble electrochemistry to nanoparticle-impact electrochemistry: Altered reaction process and possible applications

Nanoparticle-impact electrochemistry (NIE) is an electroanalytical method based on the stochastic collisions of individual nanoparticles onto an inert ultramicroelectrode. In this article, we overview different characteristics of NIE-based reactions from their ensemble counterpart, that is, enhanced mass transport, intermittent working mode, and reduced reaction time scale. A particular interest is focused on the survey of the resulting changes in the reaction process regarding enhanced reaction efficiency and rate, altered selectivity, and improved catalyst stability. A summary of the application prospect of NIE is followed, and existing challenges are provided.     

双曲柄式160摄影机在战略靶场中的应用

文章叙述了靶场经纬仪中使用摄影机的类型与特点;指出更新的双曲柄式160摄影机具有技术性能高,操作方便,可靠性好等特点。经受了多种工作考验,为多种试验提供了高精度测量数据,最后给出了几种摄影机应用情况对照表。     

Crisis curves in nonlinear business cycles

Intermittent behavior of economic dynamics is studied by a nonlinear model of business cycles when two of its control parameters, amplitude and frequency of a periodic exogenous driving force, are changed. This study points out how similar wanted situations may be reached by changing any of both parameters, and it gives a deeper understanding of what happens in actual economic data when some control parameters are changed at the same time.     

Research on the fault diagnosis technology of intermittent connection failure belonging to FPGA solder-joints in BGA package

A new method to detect intermittent faults in FPGA (field programmable gate array) of BGA (ball grid array) packages is presented. Inject proper current into measured IO port via sensor circuit, the intermittent faults will arouse impedance of the solder-joint to change intermittently, the voltage of solder-joint will also change intermittently, the fault information can be obtained through regulating the voltage signal. Compared with current monitoring method based on degradation model, this scheme is more reliable and accurate. It can prevent the catastrophic faults caused by failure of the FPGA solder-joints effectively, as well as economize the maintenance cost.     

Fourier Representation of Intermittent Flow in a Porous Medium

The field measurements and numerical results for intermittent flow regime in a sandy soil show that the time distributions of the soil water flux q(z, t), and the soil water content θ(z, t)at various depths are periodic in nature, where t is time and z is the depth (i.e., at the surface z = 0 and at depths z = − 5, − 10, − 15 cm, etc). The period of q(z, t) and θ(z, t) variations are generally determined by the sum of the duration of pulse and the duration between the initiation of two consecutive pulses of water at the soil surface. Fourier series models have been given for q(z, t) and θ(z, t) variations. The predicted Fourier results for these variations have been compared with the experimentally verified numerical results—designated as observed values. The results show that the amplitudes of these variations were damped exponentially with depth, and the phase shift increased linearly with depth.     

尿中痕量碲测定的萃取-氢化物发生原子荧光光谱法

建立了萃取－断续流动氢化物发生原子荧光光谱法测定尿中碲的分析方法。研究了仪器工作条件和试剂对碲原子荧光强度的影响、最佳条件的选择、碲在二乙基二硫代氨基甲酸盐（ＤＤＴＣ）－ＣＣＬ４体系中的萃取行为及碲（Ⅳ）的还原;探讨了共存离子对碲测定的干扰及消除方法。方法检出限（３σ）Ｏ ０．２１ＵＧ／Ｌ,相对标准偏差为１．２４％,回收率为９２％～９９％。     

Active control of intermittent noise in a room

I.IntroductionThereverberantnoisesmaybereducedwithanactivenoisecontrol(ANC)systcmformedbyacornermicrophonc-amplifier-1oudspcakersystemina.oom.lllThismeth-odbascdonthenormalmodccancelingprincip1chasalreadybeenclarifiedbothinthco-ryandexperimcnts,andthclimitationandpotcntialityofitsapp1icationalsodiscussedinapreviouspaper.Thediscussionsinthepastlimitedmost1ytothesteadyconditionofnoiscfield,andthisisextendedtothetransientcondihoninthcprcsentwork,viz.thein-llucnceofthecornerANCsystemwhenthenois…     

Improved kinetics of ethanol oxidation on Pd catalysts supported on tungsten carbides/carbon nanotubes

Pd nanoparticles on tungsten carbides modified multiwalled carbon nanotubes (Pd-WC/MWCNT) catalysts have been prepared by an intermittent microwave heating (IMH) technique for the first time. The Pd-WC/MWCNT catalysts are evaluated and show an improved kinetics for the ethanol oxidation. It is recognized that the significant increase in the catalytic activity for ethanol oxidation on Pd-WC/MWCNT is attributed to both the synergistic effect between Pd nanoparticles and the WC support and the structure effect of the MWCNT. This type catalyst can be universally used as the oxygen reduction catalyst in fuel cells and sensors both in alkaline and acidic solutions.     

Determination of mercury by intermittent flow electrochemical cold vapor generation coupled to atomic fluorescence spectrometry

A novel method for determination of mercury was developed using an intermittent flow electrochemical cold vapor generation coupled to atomic fluorescence spectrometry (IF-ECVG-AFS). The mercury vapor was generated on the surface of glassy carbon cathode in the flow cell. The operating conditions for the electrochemical generation of mercury vapor were investigated in detail, and the interferences from various ions were evaluated. Under the optimized conditions, no evident memory effects of mercury were observed. The calibration curve was linear up to 5 μg L⁻¹ Hg at 0.54 A cm⁻². A detection limit of 1.2 ng L⁻¹ Hg and a relative standard deviation of 1.8% for 1 μg L⁻¹ Hg were obtained. The accuracy of method was verified by the determination of mercury in the certified reference human hair. The ECVG avoided the use of reductants, thereby greatly reducing the contamination sources. In addition, the manifold of IF-ECVG-AFS was simple and amenable to automation.     

Intermittent counter-current extraction--effect of the key operating parameters on selectivity and throughput

Intermittent counter-current extraction (ICcE) has proved itself as a method for splitting compounds into streams and/or concentrating compounds in the column. In this paper a model mixture sample based on a modified GUESSmix (containing salicin, caffeine, aspirin, coumarin, salicylic acid, carvone, ionone and biphenyl) was separated into two eluant streams across a range of HEMWat phase system polarities from the polar system 11 through to non-polar system 23. ICcE could provide throughput of over 1 kg/day with this model sample, at the preparative scale, Changing the time cycle to adjust where the sample mixture is split into two streams was demonstrated. It is established that for the continuous running of ICcE, on a conventional twin bobbin counter-current chromatograph instrument, it is necessary to adjust the dead volumes of the flying leads to maintain similar phase retention in each column so the instrument does not become hydrodynamically and mechanically unbalanced due to the difference in densities between the upper and lower phases.