Experimental study of a liquid film flowing over a perforation

Perforations are one of the recognized geometrical features that contribute to liquid redistribution in corrugated sheet packings. Our experimental study focuses on a simplified but relevant configuration: a thin liquid film flowing on either side of a vertical plate with a circular perforation. We focus on the curtain mode when the liquid fills the perforation. Confocal chromatic imaging reveals a capillary ridge upstream of the perforation, an inertial ridge downstream, and a varicose capillary wave standing on the liquid curtain. We show that the wavelength is selected such that the velocity of the wave both satisfies Taylor's dispersion relation and matches the curtain local speed. We examine the effect of perforation size, supply conditions, and liquid properties on the curtain transition. Lastly, we propose a simple model based on a momentum balance that describes the effect of these parameters on the Reynolds number at which curtain forms.     

Determination of PNU 153429, a new polysulphonated derivative of distamycin A, in rat plasma by reversed-phase ion-pair high-performance liquid chromatography with ultraviolet detection

A rapid and selective ion-pair high-performance liquid chromatographic (HPLC) method for the determination of 2,2'-(carbonylbis(imino-N-methyl-4,2-pyrrole carbonylimino (N-methyl-4,2-pyrrole)carbonylimino)) -bis(1,5-naphtalenedisulphonic acid), tetrasodium salt (PNU 153429,I) in rat plasma has been developed. I is a new drug currently under investigation for the treatment of rheumatoid arthritis. Aliquots of 100 microliters of plasma spiked with 10 microliters of internal standard solution (PNU 145156E, I.S.) were added to 100 microliters of acetonitrile and vortex mixed. After centrifugation, diluted aliquots of the supernatant were transferred to autosampler vials and analyzed by reversed-phase ion-pair liquid chromatography under isocratic conditions. The retention times of I.S. and I were approximately equal to 8 and 12 min, respectively. Quantitation was achieved by ultraviolet detection at 323 nm. The assay had a limit of quantitation of 0.1 micrograms ml-1 when 100 microliters of plasma were analyzed. The linearity, precision and accuracy of the method were evaluated. No interference from blank rat, mouse, dog, monkey and human plasma was observed. The suitability of the method for in vivo samples was checked by analysis of plasma samples drawn from three cannulated male rats that had received a single 100 mg kg-1 i.v. dose of the test compound.     

A sensitive procedure for the quantitation of free and N-(2-hydroxypropyl) methacrylamide polymer-bound doxorubicin (PK1) and some of its metabolites, 13-dihydrodoxorubicin, 13-dihydrodoxorubicinone and doxorubicinone, in human plasma and urine by reversed-phase HPLC with fluorimetric detection

A high-performance liquid chromatographic assay has been developed and validated for the determination in plasma and urine of doxorubicin (DXR) and some of its metabolites released in vivo from an N-(2-hydroxypropyl)methacrylamide (HPMA) polymer containing DXR linked through its aminosugar moiety to the polymer via an oligopeptide spacer (PK1). The method also allows measurement of the DXR still bound to the polymer. Following addition of two internal standards, the free compounds were extracted twice with isopropanol-chloroform (25:75, v/v). The first extraction was performed at physiological pH and the second after buffering at pH 8.4, in order to extract the aglycones and the glycosides, respectively. Determination of total DXR (polymer-bound plus free DXR) was performed, after quantitative acid hydrolysis to release doxorubicinone from free or polymer-bound DXR, by extraction with the same solvent mixture at pH 7.4. In both cases the organic phase was evaporated to dryness; the compounds were then separated by reversed-phase high-performance liquid chromatography (HPLC) under isocratic conditions and quantitated by fluorimetric detection. In the chromatograms all the analytes appeared to be separated at the baseline and no interference from blank human plasma and urine was observed. The suitability of the method for in vivo samples was checked by the analysis of plasma and urine samples obtained from a cancer patient who had received a single intravenous dose of the test compound.     

Nonvolatile Reconfigurable Phase‐Change Metadevices for Beam Steering in the Near Infrared

The development of flat, compact beam‐steering devices with no bulky moving parts is opening up a new route to a variety of exciting applications, such as LIDAR scanning systems for autonomous vehicles, robotics and sensing, free‐space, and even surface wave optical signal coupling. In this paper, the design, fabrication and characterization of innovative, nonvolatile, and reconfigurable beam‐steering metadevices enabled by a combination of optical metasurfaces and chalcogenide phase‐change materials is reported. The metadevices reflect an incident optical beam in a mirror‐like fashion when the phase‐change layer is in the crystalline state, but reflect anomalously at predesigned angles when the phase‐change layer is switched into its amorphous state. Experimental angle‐resolved spectrometry measurements verify that fabricated devices perform as designed, with high efficiencies, up to 40%, when operating at 1550 nm. Laser‐induced crystallization and reamorphization experiments confirm reversible switching of the device. It is believed that reconfigurable phase‐change‐based beam‐steering and beam‐shaping metadevices, such as those reported here, can offer real applications advantages, such as high efficiency, compactness, fast switching times and, due to the nonvolatile nature of chalcogenide phase‐change materials, low power consumption.     

Origin of the Exclusive Ternary Electroluminescent Behavior of BN‐Doped Nanographenes in Efficient Single‐Component White Light‐Emitting Electrochemical Cells

White‐light‐emitting electrochemical cells (WLECs) still represent a significant milestone, since only a few examples with moderate performances have been reported. Particularly, multiemissive white emitters are highly desired, as a paradigm to circumvent phase separation and voltage‐dependent emission color issues that are encountered following host:guest and multilayered approaches. Herein, the origin of the exclusive white ternary electroluminescent behavior of BN‐doped nanographenes with a B₃N₃ doping pattern (hexa‐perihexabenzoborazinocoronene) is rationalized, leading to one of the most efficient (≈3 cd A^?1) and stable‐over‐days single‐component and single‐layered WLECs. To date, BN‐doped nanographenes have featured blue thermally activated delayed fluorescence (TADF). This doping pattern provides, however, white electroluminescence spanning the whole visible range (x/y CIE coordinates of 0.29–31/0.31–38 and average color rendering index (CRI) of 87) through a ternary emission involving fluorescence and thermally activated dual phosphorescence. This temperature‐dependent multiemissive mechanism is operative for both photo‐ and electroluminescence processes and holds over the device lifespan, regardless of the device architecture, active layer composition, and operating conditions. As such, this work represents a new stepping‐stone toward designing a new family of multiemissive white emitters based on BN‐doped nanographenes that realizes one of the best‐performing single‐component white‐emitting devices compared to the prior‐art.     

RF MEMS packaged switch evaluation tests up to 25 GHz

This article presents the results of the series of experimental tests of a packaged RF MEMS switch manufactured as a chip on a silicon substrate in the Center for Materials and Microsystems of Fondazione Bruno Kessler. Experiments have been performed up to 25 GHz and included S-parameters check in different operation and environmental conditions, including variation of input power, ambient temperature and number of switching cycles. Presented RF MEMS SPST switch is a basic element of more complex reconfigurable networks such as SPxT switches, phase shifters, power attenuators etc.

     

Out-of-plane deformation and pull-in voltage of cantilevers with residual stress gradient: experiment and modelling

The out-of-plane deformation and the pull-in voltage of electrostatically actuated cantilevers with a residual stress gradient, is investigated in the length range 100–300 µm. Measured pull-in voltages are compared with calculations, which are obtained using previously proposed analytical expressions and a finite element method (FEM) modelling. In particular, a simplified model of the residual stress distribution inside cantilevers is formulated that enables FEM simulation of measured out-of-plane deformations and pull-in voltages for all lengths of fabricated cantilevers. The presented experimental results and FEM model are exploitable in the design of cantilever-based microelectromechanical systems, in order to provide a reliable prediction of the influence of residual stress gradient on device shape and pull-in voltage.

     

Object interaction and task programming by demonstration in visuo-haptic augmented reality

A visuo-haptic augmented reality system is presented for object manipulation and task learning from human demonstration. The proposed system consists of a desktop augmented reality setup where users operate a haptic device for object interaction. Users of the haptic device are not co-located with the environment where real objects are present. A three degrees of freedom haptic device, providing force feedback, is adopted for object interaction by pushing, selection, translation and rotation. The system also supports physics-based animation of rigid bodies. Virtual objects are simulated in a physically plausible manner and seem to coexist with real objects in the augmented reality space. Algorithms for calibration, object recognition, registration and haptic rendering have been developed. Automatic model-based object recognition and registration are performed from 3D range data acquired by a moving laser scanner mounted on a robot arm. Several experiments have been performed to evaluate the augmented reality system in both single-user and collaborative tasks. Moreover, the potential of the system for programming robot manipulation tasks by demonstration is investigated. Experiments show that a precedence graph, encoding the sequential structure of the task, can be successfully extracted from multiple user demonstrations and that the learned task can be executed by a robot system.