Electrical measurement of droplet sizes in fast-flowing wet steam

A new method has been developed for determining droplet sizes that extends the range of the Wicks-Dukler method. Experimental results are presented.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 36, No. 5, pp. 841–846, May, 1979.     

Electrical breakdown of individual Si nanochains and silicide nanochains

Electron transport across individual Si nanochains and silicide nanochains is investigated using a micro-manipulator in a transmission electron microscope. The current increases nonlinearly with increasing the bias voltage. Electrical breakdowns occur with a current typically as large as 10(1)-10(2) nA. Furthermore, some FN plots exhibit a bend presumably due to the formation of a heavily distorted nanotube of carbon.     

Ultrasensitive and high-throughput fluorescence analysis of droplet contents with orthogonal line confocal excitation

This paper describes a simple modification to traditional confocal fluorescence detection that greatly improves signal-to-noise (s/n) for the high-speed analysis of droplet streams. Rather than using the conventional epi geometry, illumination of the droplet was in the form of a line that is orthogonal to both the direction of flow and the light-collection objective. In contrast to the epi geometry where we observed high levels of scattering background from the droplets, we detected more than 10-fold less background (depending on the laser power used) when orthogonal-line-confocal illumination was used. We characterized this improvement using a standard microfluidic platform over a range of analyte concentrations and observed an improvement in limits of detection of greater than 10. Using this method, we were able to analyze picomolar concentrations of analytes contained within picoliter-volume droplets at a rate of greater than 350 droplets per second.     

Electrical contacts to individual colloidal semiconductor nanorods

We report the results of charge transport studies on single CdTe nanocrystals contacted via evaporated Pd electrodes. Device charging energy, E c, monitored as a function of electrode separation drops suddenly at separations below approximately 55 nm. This drop can be explained by chemical changes induced by the metal electrodes. This explanation is corroborated by ensemble X-ray photoelectron spectroscopy studies of CdTe films as well as single particle measurements by transmission electron microscopy and energy dispersive X-rays. Similar to robust optical behavior obtained when nanocrystals are coated with a protective shell, we find that a protective SiO 2 layer deposited between the nanocrystal and the electrode prevents interface reactions and an associated drop in E c,max. This observation of interface reactivity and its effect on electrical properties has important implications for the integration of nanocrystals into conventional fabrication techniques and may enable novel nanomaterials.     

Electrical arc contour cutting based on a compound arc breaking mechanism

Electrical arc contour cutting (EACC) is a novel high-efficiency material cutting process that applies arc plasma to perform efficient and economical contour cutting of difficult-to-cut materials. Compared to conventional electrical arc machining (EAM), this process can remove the allowance of open structures and plates in bulk mode, rather than entirely in the form of debris. Compared with existing contour cutting methods, EACC possesses the advantages of high cutting efficiency and a deep cutting depth. Particularly, a compound arc breaking mechanism (CABM), which integrates hydrodynamic force and mechanical motion, has been applied to control the discharge arc column in EACC, while also strengthening the debris expelling effect in the narrow discharge gap. The CABM implementation conditions were studied, based on arc column distortion images captured by a high-speed camera and simulation results of the flow field and debris distribution. A set of machining experiments was designed and conducted to optimize the performance of the proposed process. Finally, a SiC_p/Al metal matrix composite (MMC) space station workpiece was machined to verify the feasibility and efficiency of this process.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00406-0     

Performance of droplet generator and droplet collector in liquid droplet radiator under microgravity

The Liquid Droplet Radiator (LDR) has an advantage over comparable conventional radiators in terms of the rejected heat power-weight ratio. Therefore, the LDR has attracted attention as an advanced radiator for high-power space systems that will be prerequisite for large space structures. The performance of the LDR under microgravity condition has been studied from the viewpoint of operational space use of the LDR in the future. In this study, the performances of a droplet generator and a droplet collector in the LDR are investigated using drop shafts in Japan: MGLAB and JAMIC. As a result, it is considered that (1) the droplet generator can produce uniform droplet streams in the droplet diameter range from 200 to 280 [μm] and the spacing range from 400 to 950 [μm] under microgravity condition, (2) the droplet collector with the incidence angle of 35 degrees can prevent a uniform droplet stream, in which droplet diameter is 250 [μm] and the velocity is 16 [m/s], from splashing under microgravity condition, whereas splashes may occur at the surface of the droplet collector in the event that a nonuniform droplet stream collides against it.     

Performance of droplet generator and droplet collector in liquid droplet radiator under microgravity

The Liquid Droplet Radiator (LDR) has an advantage over comparable conventional radiators in terms of the rejected heat power-weight ratio. Therefore, the LDR has attracted attention as an advanced radiator for high-power space systems that will be prerequisite for large space structures. The performance of the LDR under microgravity condition has been studied from the viewpoint of operational space use of the LDR in the future. In this study, the performances of a droplet generator and a droplet collector in the LDR are investigated using drop shafts in Japan: MGLAB and JAMIC. As a result, it is considered that (1) the droplet generator can produce uniform droplet streams in the droplet diameter range from 200 to 280 [μm] and the spacing range from 400 to 950 [μm] under microgravity condition, (2) the droplet collector with the incidence angle of 35 degrees can prevent a uniform droplet stream, in which droplet diameter is 250 [μm] and the velocity is 16 [m/s], from splashing under microgravity condition, whereas splashes may occur at the surface of the droplet collector in the event that a nonuniform droplet stream collides against it.     

Three-dimensional optical control of individual quantum dots

We show that individual colloidal CdSe-core quantum dots can be optically trapped and manipulated in three dimensions by an infrared continuous wave laser operated at low laser powers. This makes possible utilizing quantum dots not only for visualization but also for manipulation, an important advantage for single molecule experiments. Moreover, we provide quantitative information about the magnitude of forces applicable to a single quantum dot and of the polarizability of an individual quantum dot.     

Electrical transport studies of individual IrO(2) nanorods and their nanorod contacts

We have studied the electrical transport properties of individual single-crystalline IrO(2) nanorods prepared by the metal-organic chemical vapour deposition method. With the help of the standard electron-beam lithographic technique, individual nanorods are contacted by Cr/Au submicron electrodes from above. Utilizing two-probe, three-probe and four-probe measurement configurations, not only the intrinsic electrical transport properties of the individual nanorods but also the electronic contact resistances, R(c)(T), have been determined from 300?K down to liquid-helium temperatures. Our measured resistivity behaviour of the nanorods is in close agreement with the current theoretical understanding of this rutile material. On the other hand, we found that the temperature behaviour of the electronic contact resistance obeys the law [Formula: see text] over an extremely wide temperature range, from approximately 100?K down to liquid-helium temperatures. This latter conduction process is ascribed to the hopping of electrons through nanoscale Cr granules and/or an amorphous coating incidentally formed at the interface between the submicron Cr/Au electrode and the nanorod.     

Electrical control of a solid-state flying qubit

Solid-state approaches to quantum information technology are attractive because they are scalable. The coherent transport of quantum information over large distances is a requirement for any practical quantum computer and has been demonstrated by coupling super-conducting qubits to photons. Single electrons have also been transferred between distant quantum dots in times shorter than their spin coherence time. However, until now, there have been no demonstrations of scalable 'flying qubit' architectures-systems in which it is possible to perform quantum operations on qubits while they are being coherently transferred-in solid-state systems. These architectures allow for control over qubit separation and for non-local entanglement, which makes them more amenable to integration and scaling than static qubit approaches. Here, we report the transport and manipulation of qubits over distances of 6?μm within 40?ps, in an Aharonov-Bohm ring connected to two-channel wires that have a tunable tunnel coupling between channels. The flying qubit state is defined by the presence of a travelling electron in either channel of the wire, and can be controlled without a magnetic field. Our device has shorter quantum gates (<1?μm), longer coherence lengths (～86?μm at 70?mK) and higher operating frequencies (～100?GHz) than other solid-state implementations of flying qubits.     

Acoustic droplet vaporization for temporal and spatial control of tissue occlusion: a kidney study

Acoustic droplet vaporization (ADV) has been introduced with the potential application of tumor treatment via occlusion and subsequent necrosis. New Zealand White rabbits were anesthetized, and their left kidney was externalized. An imaging array and single-element transducer were positioned in a tank with direct access to the kidney's vasculature and renal artery. Filtered droplet emulsions (diameter <6 microm) were injected intra-arterially (IA) into the left heart during insonification of the renal artery, and the extent of blood flow reduction by ADV was compared to the untreated right kidney. Flow cytometry (using colored microspheres) of kidney tissue samples and reference blood from the femoral artery allowed the quantitative estimation of regional blood flow. A maximum regional blood flow reduction in the treated region of >90% and an average organ perfusion reduction of >70% was achieved using ADV. After treatment of the left kidney, the control kidney on the contralateral side showed a maximum decrease in regional blood flow of 18% relative to the pre-ADV baseline. Image-based hyper-echogenicity from ADV of IA injections was monitored for approximately 90 minutes, and cortex perfusion was reduced by >60% of its original value for more than 1 hour. This could be enough time for the onset of cell death and possible tumor treatment via ischemic necrosis. Moreover, currently used radiofrequency tissue ablation-based tumor treatment could benefit from ADV due to the decreased heat loss via vascular cooling.     

Dynamic and reversible control of 2D membrane protein concentration in a droplet interface bilayer

We form an artificial lipid bilayer between a nanolitre aqueous droplet and a supporting hydrogel immersed in an oil/lipid solution. Manipulation of the axial position of the droplet relative to the hydrogel controls the size of the bilayer formed at the interface; this enables the surface density of integral membrane proteins to be controlled. We are able to modulate the surface density of the β-barrel pore-forming toxin α-hemolysin over a range of 4 orders of magnitude within a time frame of a few seconds. The concentration changes are fully reversible. Membrane protein function and diffusion are unaltered, as measured by single molecule microscopy and single channel electrical recording.     

电润湿效应控制介质上液滴运动的数值模拟

电润湿效应是利用电极阵列所产生的变化电场,改变液滴表面张力,实现控制液滴在微小通道内的运动.本文采用数值模拟方法模拟液滴在介质上的电润湿效应.用level set函数方法捕捉液滴表面,得到表面张力,通过压力方程和N-S方程依次求解压力场和速度场.采用3×3的电极方阵控制液滴运动,数值结果表明电润湿效应能在较低电压下,实现对液滴移动的控制.并给出液滴可移动的电极间距极限值100μm.     

基于PLC对三维立体运动系统的电气控制及应用

工业生产过程中很多采用三维运动控制,该运动在很多场合还是采用继电器接触器控制,控制的稳定性和可靠性不高,消耗了大量的人力和财力,因此对此类运动的特性作一个总结,并建立系统的通用控制目标,采用PLC的控制方法对其控制.该控制方法适用于所有的三维运动,在具体应用中,只要通过编程改变其参数就可以达到运动控制的目的.将该方法应用在污水处理移动罩滤池的三维立体控制中,取得了良好的控制效果.     

Acceptance control and guardbanding for error‐prone individual measurements

The concept of fractional nonconformance was recently proposed to assess the probability of conformance when measurements are error‐prone. Applications of fractional nonconformance assessment include acceptance sampling inspection and short‐run process control. In this study, we introduce a fractional nonconformance‐based one‐sided acceptance control chart to monitor a short‐run process as well as decide the acceptability of products manufactured from the process. The guardband technique is also incorporated in the proposed approach to reduce the impact of measurement errors. Guardband selection is investigated for both independent and autocorrelated processes. Our analysis shows that guardbanding is beneficial for short‐run production environments. The optimum guardbands obtained under risk and cost models are also found to be consistent.     

A joint replenishment policy with individual control and constant size orders

We consider inventory systems with multiple items under stochastic demand and jointly incurred order setup costs. The problem is to determine the replenishment policy that minimises the total expected ordering, inventory holding, and backordering costs–the so-called stochastic joint replenishment problem. In particular, we study the settings in which order setup costs reflect the transportation costs and have a step-wise cost structure, each step corresponding to an additional transportation vehicle. For this setting, we propose a new policy that we call the (s, 𝒬) policy, under which a replenishment order of constant size 𝒬 is triggered whenever the inventory position of one of the items drops to its reorder point s. The replenishment order is allocated to multiple items so that the inventory positions are equalised as much as possible. The policy is designed for settings in which backorder and setup costs are high, as it allows the items to independently trigger replenishment orders and fully exploits the economies of scale by consistently ordering the same quantity. A numerical study is conducted to show that the proposed (s, 𝒬) policy outperforms the well-known (𝒬, S) policy when backorder costs are high and lead times are small.     

Electrical control of the superconducting-to-insulating transition in graphene-metal hybrids

Graphene is a sturdy and chemically inert material exhibiting an exposed two-dimensional electron gas of high mobility. These combined properties enable the design of graphene composites, based either on covalent or non-covalent coupling of adsorbates, or on stacked and multilayered heterostructures. These systems have shown tunable electronic properties such as bandgap engineering, reversible metal-insulating transition or supramolecular spintronics. Tunable superconductivity is expected as well, but experimental realization is lacking. Here, we show experiments based on metal-graphene hybrid composites, enabling the tunable proximity coupling of an array of superconducting nanoparticles of tin onto a macroscopic graphene sheet. This material allows full electrical control of the superconductivity down to a strongly insulating state at low temperature. The observed gate control of superconductivity results from the combination of a proximity-induced superconductivity generated by the metallic nanoparticle array with the two-dimensional and tunable metallicity of graphene. The resulting hybrid material behaves, as a whole, like a granular superconductor showing universal transition threshold and localization of Cooper pairs in the insulating phase. This experiment sheds light on the emergence of superconductivity in inhomogeneous superconductors, and more generally, it demonstrates the potential of graphene as a versatile building block for the realization of superconducting materials.     

Electrical characterization of an individual nanowire using flexible nanoprobes fabricated by atomic force microscopy-based manipulation

Nanowires have emerged as promising one-dimensional materials with which to construct various nanocircuits and nanosensors.However,measuring the electrical properties of individual nanowires directly remains challenging because of their small size,thereby hindering the comprehensive understanding of nanowire-based device performance.A crucial factor in achieving reliable electrical characterization is establishing well-determined contact conditions between the nanowire sample and the electrodes,...     

Electrical properties of individual CoPt/Pt multilayer nanowires characterized by in situ SEM nanomanipulators

Here we report for the first time accurate and comprehensive measurements of electrical properties of individual CoPt/Pt multilayer nanowires both with periodic and non-periodic layer structures. A remarkably high failure current density of 1.69 × 10(12) A m(-2) for the periodic MNW and a similar 1.76 × 10(12) A m(-2) for the non-homogeneous MNW has been measured. The resistance of both types of multilayer nanowire structures are well fitted by a series resistance model, determining the separate resistance contribution of the component layers and magnetic/nonmagnetic interfaces for a single multilayer nanowire. The field-dependent interface resistance of both samples is calculated, 13.2 Ω for periodic layer structures and 4.84 Ω for non-periodic layer structures. The clear physical picture of the resistance distribution within individual multilayer nanowires is then determined. The accurate electrical testing of magnetic multilayer nanowires provides basic and necessary electrical parameters for their usage as building blocks or interconnects in nanoelectronics and nanosensors.