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Light-induced orientation of gas phase molecules is a long-pursued goal in physics and chemistry. Here, we experimentally demonstrate a six-fold increase in the terahertz-induced orientation of iodomethane (CH3I) molecules at room temperature, provided by rotational pre-excitation with a moderately intense near-IR pulse. The paper highlights the underlying interference of multiple coherent transition pathways within the rotational coherence manifold and is analyzed accordingly. Our experimental and theoretical results provide desirable and practical means for all-optical experiments on oriented molecular ensembles. [ABSTRACT FROM AUTHOR]

Despite significant advancements in in vitro cardiac modeling approaches, researchers still lack the capacity to obtain in vitro measurements of a key indicator of cardiac function: contractility, or stroke volume under specific loading conditions—defined as the pressures to which the heart is subjected prior to and during contraction. This work puts forward a platform that creates this capability, by providing a means of dynamically controlling loading conditions in vitro. This dynamic tissue loading platform consists of a thin magnetoresponsive hydrogel cantilever on which 2D engineered myocardial tissue is cultured. Exposing the cantilever to an external magnetic field—generated by positioning magnets at a controlled distance from the cantilever—causes the hydrogel film to stretch, creating tissue load. Next, cell contraction is induced through electrical stimulation, and the force of the contraction is recorded, by measuring the cantilever's deflection. Force–length‐based measurements of contractility are then derived, comparable to clinical measurements. In an illustrative application, the platform is used to measure contractility both in untreated myocardial tissue and in tissue exposed to an inotropic agent. Clear differences are observed between conditions, suggesting that the proposed platform has significant potential to provide clinically relevant measurements of contractility. [ABSTRACT FROM AUTHOR]

Dielectric barrier discharge, originally called silent discharge, is the electrical discharge between two electrodes separated by an insulating dielectric barrier. A high-voltage alternating current is required to generate the discharge process. There are two major principles of operation to implement a high-voltage generator: resonant mode and forced mode. While operating in forced mode, the working frequency is forced by the user using internal electronic devices. On the other hand, in resonant mode, the operating frequency is determined by the resonant circuit, which includes the external capacitance, inductance, and resistance of the load. This work shows a flexible circuit based on a real-time digital signal processor and a full H-bridge that combines the two topologies and can be used as a controller for dielectric barrier discharge and a quadrupole mass filter with varying capacitance. [ABSTRACT FROM AUTHOR]

This paper presents a new, comprehensive digital circuit used for the control of a novel gas chromatograph mass spectrometer (GC-MS) interface that is based on supersonic molecular beam (SMB). The circuit includes a Texas Instruments 150 MHz digital signal controller (DSC), high voltage amplifiers for 8 independent channels and 4 independent channels of high resolution pulse width modulation (PWM). The circuit, along with a sophisticated embedded program and a custom made personal computer (PC) application, control all aspects of the interface: smart filament emission-current stabilization, static and scanning mass-dependent ion-source voltages, transfer-line heater proportional integral differential (PID) controls with thermocouple feedbacks, on/off valves, relays and several peripheral device controls that enable the full operation of a turbo-molecular vacuum pump, and of gas flow and pressure controllers. All aspects of this comprehensive controller were successfully tested. The signal for the 450 Th ion (C32H66) for example increased by 123% which is a significant increase. It is obvious that correctly tuned dynamic voltages can guarantee the optimal signal for each mass. [ABSTRACT FROM AUTHOR]

In the last three decades, the energy conversion market has been dominated by switching power converters due to reduction of size and cost of electronic components. This market includes four types of conversion: DC–DC, DC–AC, AC–DC, and AC–AC. While the first three types are applied directly in a single conversion, the AC–AC converter is comprised of two serial converters leading to an AC–DC–AC conversion. This article introduces, for the first time, a real direct single-stage AC–AC conversion electronic transformer. The single stage AC–AC converter is fabricated using a unique high efficiency topology, combined with the advantages of dual-stage power-quality protection. This single-stage AC–AC regulated electronic transformer is stabilized, controlled, protected, and can lock onto any line voltage (110 or 220 V) with a frequency of 45–65 Hz. Stabilization is achieved by fast pulse-width modulation technology, applied by two-way fast solid-state switches. The transformer is controlled by a 150 MHz digital signal processor and is fully protected against overcurrent and output short circuits. Our first stage transformer is a single-phase device with 5 kW power with an efficiency of better than 97% with one-tenth of the weight and volume of present conventional electromechanical transformers. [ABSTRACT FROM AUTHOR]

Shape‐morphing active networks of mesoscale filaments are a common hierarchical feature in biology for applying forces, transporting materials, and inducing motility with microscale resolution. Synthetic morphing systems of similar dimensions and capabilities hold potential for a range of technological applications, from micro‐muscles to shape‐morphing optical devices. Here, the fabrication of highly‐ordered 2D networks hierarchically constructed of thermoresponsive mesoscale polymeric fibers, which can exhibit morphing with microscale resolution, is presented. It is demonstrated both experimentally and computationally that the morphing of such networks strongly depends on the physical attributes of the single fiber, in particular on two intrinsic length scales—the fiber diameter and mesh size, which stems from network's density. It is shown that depending on these parameters, such fiber‐networks exhibit one of two thermally driven morphing behaviors: i) the fibers stay straight, and the network preserves its ordered morphology, exhibiting a bulk‐like behavior; or ii) the fibers buckle and the network becomes messy and highly disordered. Notably, in both cases, the networks display memory and regain their original ordered morphology upon shrinking. This hierarchically induced phase transition, demonstrated here on a range of networks, offers a new way of controlling the shape‐morphing of synthetic materials with mesoscale resolutions. [ABSTRACT FROM AUTHOR]

Modulation technique is used to detect a short-range interaction between a probe and a sample of a tunneling near-field optical microscope. It was observed that the effect of the coupled dipoles interaction is negligible in conventional near-field microscopes and it dominates the modulated signal at scanning distances.

The various effects of the laser wavelength on the charge state resolved ion energy distributions obtained from the laser-induced sn plasma are determined. The laser wavelength is shown to be dependent on the laser energy absorption, which is found to lead to the differences in the ion energy distributions.

This work presents a digital mixer that receives two signals at different frequencies and produces their difference or their sum. Unlike analog circuits that are limited in their ability to separate between close frequencies and require an additional filtering step, we present a digital signal processor-based circuit with excellent frequency separation capabilities. Since software is used to calculate the output function, the obtained output signal is practically unlimited. [ABSTRACT FROM AUTHOR]

Fluorescence is a type of electromagnetic spectroscopy that employs emission from a sample. It involves using a beam of light that excites the electrons in specific compounds and causes them to emit light of a lower energy. As proof of principle, a computer controlled experiment is described employing a single microliter capillary tube setup, using a two wavelength excitation of a single wavelength emission of hydroxypyrene trisulfonate. The same setup can be manipulated for the other pH-sensitive fluorescence ratiometric systems. In addition, this setup can be scaled up for high-throughput measurements. [ABSTRACT FROM AUTHOR]

In electron ionization source, electrons are produced through thermionic emission by heating a wire filament, accelerating the electrons by high voltage, and ionizing the analyzed molecules. In such a system, one important parameter is the filament emission current that determines the ionization rate; therefore, one needs to regulate this current. On the one hand, fast responses control is needed to keep the emission current constant, but on the other hand, we need to protect the filament from damage that occurs by large filaments current transients and overheating. To control our filament current and emission current, we developed a digital circuit based on a digital signal processing controller that has several modes of operation. We used a smart algorithm that has a fast response to a small signal and a slow response to a large signal. In addition, we have several protective measures that prevent the current from reaching unsafe values. [ABSTRACT FROM AUTHOR]

We have binarily encoded written monologues in a similar manner to the encoding of a continuous electrical signal of neuronal networks. The encoding keys have been carefully designed to include phrases that are co-referents. Only such keys produce binary series, which have an hierarchical fractal structure. This fractal structure can be revealed by using a statistical tool named “Fano factor”. By outlining the analogy between the hierarchical structure of neuronal electrical activity and the hierarchical structure of text, we try to link the organization of text and neuronal activity. [ABSTRACT FROM AUTHOR]

Abstract: In order to protect the sample and the tip against current transients in a scanning tunneling microscope, which in most cases damages the scanned surface and the tip, when using a bias higher than 1V, we have designed a simple and low-cost circuit that limits the tunneling current. During the evolution of the current transient, when the current exceeds a pre-determined value, a fast feedback control mechanism immediately reduces the bias and prevents the current transient from developing. In addition, we designed a fast pre-amplifier that works with this controller. We have shown that this mechanism provides a better scanning image compared to a system without such a mechanism. [Copyright &y& Elsevier]

The AFEKA – Tel Aviv Academic College of Engineering has developed a program in mechatronics studies designed not just for students of mechanical engineering but for every student in any field of engineering, as well as for experimentalists in natural sciences. This program supplies the students with tools that allow them to gain interdisciplinary insights and to carry out interdisciplinary final projects. In this paper we outline this program and give a detailed description of some unique features of the mechatronics laboratory. [ABSTRACT FROM AUTHOR]

A complete design of a compact, high voltage, multichannel programmable waveform generator, using an 8 bit microcontroller, 12 bit digital to analog converter, and high voltage operation amplifier, is presented. The user can generate the waveform by several options: classic waveform, calculator, freehand drawing, and using excel or text file. All the waveform data are stored in a nonvolatile memory of the microcontroller. The generator can work as a stand-alone instrument or conjoined with a personal computer. We used this generator as a controller for piezoelectric inertial slider. [ABSTRACT FROM AUTHOR]

Abstract: A design of a compact and low-cost programmable high-voltage pulser for a linear piezo-stepper motor, using an 8 bit reduce instruction set computers (RISC) microcontroller, a high-voltage complementary metal oxide semiconductor (HVCMOS) converter, and an adjustable three-terminal high-voltage regulator is presented. The design consists of 12 independent digital channels of high-voltage output and two-operation modes—normal and smart. The generator is applied as a controller for an approach mechanism in a scanning probe microscope. The motor shows translation of about 1mm/min with step size of about 100nm. [Copyright &y& Elsevier]

A complete design of a compact precision and fast thermoelectric cooler (TEC) controller with a parallel port connection to a personal computer (PC), using a pulse width modulation technique by a dedicated smart driver, and digital control designed using very high-speed integrated circuit hardware description language is presented. The design allows replacement of the PC with an "on board" embedded microcontroller. This circuit is demonstrated as a TEC controller for a high-speed electro-optical modulator. [ABSTRACT FROM AUTHOR]

We present a new design of a compact, ultra fast, high resolution and high-powered, pulse generator for inductive load, using power MOSFET, dedicated gate driver and a digital signal controller. This design is an improved circuit of our old version controller. We demonstrate the performance of this pulse generator as a driver for a new generation of high-pressure supersonic pulsed valves. [ABSTRACT FROM AUTHOR]

We present the design principles of a compact general-purpose fast high-power (and low-cost) pulser for inductive load, using an isolate gate bipolar transistor, a dedicated smart driver unit and digital control designed in very high speed integrated circuit hardware description language. We demonstrate the performance of this pulser as a driver for a high-pressure supersonic pulsed valve. [ABSTRACT FROM AUTHOR]