自动清洗的变速控制方法

全自动划片机是融合精密机械、电子、软件、材料、自控、光电、元器件等多学科技术为一体的IC装备。高速清洗系统作为全自动划片产品的重要组成部分,直接影响着设备整体工作的质量和效率。本文对清洗系统的变速控制和精确回零技术做了初步的探讨。伺服系统采用内部速度模式的变速控制方法,解决了大转动惯量下位置控制无法稳定的问题。清洗完成后,系统寻址高精度传感器,完成清洗台上下料的回零定位。     

An improved common-mode feedback loop for the differential-difference amplifier

Unconditional stability of the high-gain amplifiers is a mandatory requirement for a reliable steady-state condition of time-discrete systems, especially for all blocks designed to sample-and-hold (S/H) circuits. Compared to differential path, the common-mode feedback loop is often affected by poles and zeros shifting that degrades the large signal response of the amplifiers. This drawback is made worse in some well-known topologies as the difference-differential amplifier (DDA) that shows non-constant transconductance and poor linearity. This work proposes a body-driven positive-feedback frequency compensation technique (BD-PFFC) to improve the linearity for precision DDA-based S/H applications. Theoretical calculations and circuit simulations carried out in a 0.13 μm process are also given to demonstrate its validity.     

Reversible Fragmentation and Self‐Assembling of Nematic Liquid Crystal Droplets on Functionalized Pyroelectric Substrates

Investigation on the behavior of nematic liquid crystals on functionalized polar dielectric crystal substrates is accomplished. Very interesting effects can be observed in maneuvering liquid crystal droplets on the substrate surface, driven by electric fields generated by pyroelectric effect. Reversible drops fragmentation and self‐assembling in different configurations can be achieved. The dynamics of the observed phenomena is studied and the repeatability of the process is full assessed.     

Isoenzymes of wheat o-diphenolase revealed by column isoelectric focusing

Summary Common wheat o-diphenolase at different purification steps has been submitted to column isoelectric focusing electrophoresis. The fraction purified with calcium phosphate gel shows multiple forms focused at pI 3.60, 4.95, 6.80, and 9.60. The enzyme activity and the purification degree of the four enzymatic components obtained have been calculated. The major fraction recovered after purification by chromatography on DEAE-cellulose does not display other multiple forms; however, it has some enzymatically inactive proteins well separated in the pH-gradient. The enzymatic protein, focused at pI 9.60, thus achieves a 1753-fold purification over the crude extract. The application of the technique allows a characterization of the wheat o-diphenolase and its recovery in highly purified form.

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Isoenzyme von o-Diphenoloxydase aus Weichweizen, identifiziert durch isoelektrisches Fokussieren über Säule

Zusammenfassung Weichweizen-o-Diphenoloxydasen verschiedener Reinigungsstufen wurden über eine Säule isoelektrisch focussiert. Das durch Calciumphosphatgel gereinigte Enzym (Fraktion C) zeigt 4 multiple Formen, focussiert bei pI 3,60; 4,65; 6,80 und 9,60. Die Aktivität und der Reinheitszustand von diesen vier Formen wurden berechnet. Die Fraktion C wurde durch Chromatographie über Cellulose weiter gereinigt. Die in größeren Mengen gewonnene Fraktion zeigte beim isoelektrischen Focussieren keine multiple Formen mehr, nur eine Trennung von enzymatisch inaktiven Proteinen beim pH-Gradienten. Das enzymatisch aktive Protein, focussiert bei pI 9,60, zeigte einen 1753 mal besseren Reinheitszustand als das Rohenzym. Die Anwendung dieser Technik erlaubt die Charakterisierung der Weichweizen-o-Diphenoloxydasen und ihre Gewinnung in einem hochgereinigten Zustand.

     

Carbon nanotubes/polydimethylsiloxanes systems for thermal management of miniaturized electronic components

The thermal performances of nanocomposite layers formed by Single-walled Carbon Nanotubes (SWCNT) dispersed in 2 different kind of polydimethyl-siloxane (PDMSO) matrices has been investigated by measuring the thermal resistance under conditions similar to the ones used for thermal management in microelectronics. A series of nanocomposite samples with thickness in the range 25 microm(-1) cm have been tested. The nanocomposites were prepared varying the amounts of nanotubes embedded in the matrix (from 0.1 to 5%w). In some cases also microsized graphites were mixed to the nanotube's fillers. For 25 micron thick layers, the thermal resistance of the neat silicone specimen can be reduced of 54% with the addition of 2%w carbon nanotubes. The variation of thermal conductivity as a function of the SWCNT's loading is reported and discussed. Furthermore the dispersion's effects of the nanotubes in the layers and the effects on the realization of a net-like system have been investigated.     

Computational fluid dynamic simulations of image-based stented coronary bifurcation models

One of the relevant phenomenon associated with in-stent restenosis in coronary arteries is an altered haemodynamics in the stented region. Computational fluid dynamics (CFD) offers the possibility to investigate the haemodynamics at a level of detail not always accessible within experimental techniques. CFD can quantify and correlate the local haemodynamics structures which might lead to in-stent restenosis. The aim of this work is to study the fluid dynamics of realistic stented coronary artery models which replicate the complete clinical procedure of stent implantation. Two cases of pathologic left anterior descending coronary arteries with their bifurcations are reconstructed from computed tomography angiography and conventional coronary angiography images. Results of wall shear stress and relative residence time show that the wall regions more prone to the risk of restenosis are located next to stent struts, to the bifurcations and to the stent overlapping zone for both investigated cases. Considering a bulk flow analysis, helical flow structures are generated by the curvature of the zone upstream from the stent and by the bifurcation regions. Helical recirculating microstructures are also visible downstream from the stent struts. This study demonstrates the feasibility to virtually investigate the haemodynamics of patient-specific coronary bifurcation geometries.     

Profiling selected phytochemicals and nutrients in different tissues of the multipurpose tree Moringa oleifera L., grown in Ghana

The purpose of this new study was to determine the types and levels of major phytochemicals (non-nutrients) and nutrients in the different tissues from vegetative and flowering Moringa oleifera L. an important multipurpose crop. Rhamnose and acetyl-rhamnose-substituted glucosinolates were found in all of the M. oleifera tissues with different profiles depending on the tissue. In addition the tissues of M. oleifera had a relatively complex flavonoid profile consisting of glucosides, rutinosides, malonylglucosides and traces of acetylglucosides of kaempferol, quercetin and isorhamnetin. Fatty acid profiling of the different tissues showed that leaves were rich in palmitic (16:0) and linolenic (18:3) acid whereas seeds were predominated by oleic acid (18:1). Roots were rich in palmitic and oleic acid, whereas stems and twigs predominately contained palmitic acid. Potassium, magnesium and calcium were the predominant minerals in all of the tissues. Low levels of selenium were detected only in whole seeds.