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。     

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.     

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.     

Characterisation of Italian commercial apricot juices by high-performance liquid chromatography analysis and multivariate analysis

The modern fruit juice industry needs their products to be characterized by high-quality attributes to meet consumers’ expectation. In this view, the composition of 26 Italian commercial apricot juices obtained from organic, integrated and conventional agriculture was analysed for carbohydrates, organic acids, amino acids, phenolic compounds and furanic compounds by high-performance liquid chromatography (HPLC). The content of 5-hydroxymethylfurfural in apricot juices (range 0.1–18 mg/l) was within the regulatory limit of 20 mg/l. The lack of furanic compounds in apricot fresh fruits confirmed their importance as quality markers of heating condition during processing and storage of fruit juices. Univariate analysis disclosed some significant differences among the composition of the apricot juices in terms of glucose, fructose, malic acid, glycine, chlorogenic acid, rutin, and a^∗-parameter (redness). Principal component analysis on chemical composition of apricot juices resulted in two principal components (PCs) that accounted for 66% of the total variance. Organic apricot juices showed some separation from the other juices, whereas a lack of distinction between integrated and conventional juices appeared.     

Removal of pharmaceuticals in sewage treatment plants in Italy

A listing of "priority pharmaceuticals" for human use in Italy resulted in the selection of 26 pharmaceuticals, belonging to 11 therapeutic classes. They were analyzed by liquid chromatography-tandem mass spectrometry, their occurrence was assessed in six sewage treatment plants (STPs), and the loads and the removal rates (RR) were studied. Total loads ranged from 1.5 to 4.5 g/day/1000 inhabitants in influents and 1.0 and 3.0 g/day/1000 inhabitants in effluents. Total RR in STPs were mostly lower than 40%. Pharmaceuticals could be divided into three groups according to their behavior in STPs: one group with RR higher in summer than in winter, one group with RR similar in summer and winter, and a last group not removed. Last, we studied the distribution and fate of residual pharmaceuticals in the surface waters receiving the effluents of the STPs and identified degradation and sorption as the major factors affecting attenuation. Ciprofloxacin, ofloxacin, sulfamethoxazole (antibiotics), atenolol (cardiovascular drug), ibuprofen (antiinflammatory), furosemide, hydrochlorothiazide (diuretics), ranitidine (gastrointestinal drug), and bezafibrate (lipid regulator) were the most abundant residual drugs, thus those of environmental concern.     

Functional Properties of Plasticized Bio-Based Poly(Lactic Acid)_Poly(Hydroxybutyrate) (PLA_PHB) Films for Active Food Packaging

Fully bio-based and biodegradable active films based on poly(lactic acid) (PLA) blended with poly(3-hydroxybutyrate) (PHB) and incorporating lactic acid oligomers (OLA) as plasticizers and carvacrol as active agent were extruded and fully characterized in their functional properties for antimicrobial active packaging. PLA_PHB films showed good barrier to water vapor, while the resistance to oxygen diffusion decreased with the addition of OLA and carvacrol. Their overall migration in aqueous food simulant was determined and no significant changes were observed by the addition of carvacrol and OLA to the PLA_PHB formulations. However, the effect of both additives in fatty food simulant can be considered a positive feature for the potential protection of foodstuff with high fat content. Moreover, the antioxidant and antimicrobial activities of the proposed formulations increased by the presence of carvacrol, with enhanced activity against Staphylococcus aureus if compared to Escherichia coli at short and long incubation times. These results underlined the specific antimicrobial properties of these bio-films suggesting their applicability in active food packaging.     

Coating-Activation and Antimicrobial Efficacy of Different Polyethylene Films with a Nisin-Based Solution

Antimicrobial packaging can be considered an extremely challenging technology that could have a significant impact on shelf-life extension and food safety of fresh meat and meat products. In this study, different commercial polyethylene films differing in vinyl acetate ethylene, erucamide contents, and oxygen permeability were used for the coating treatment with a nisin-based antimicrobial solution (NS). Detection and measurement of the activity of the NS was determined against different food spoilage bacteria. NS was then spread manually on food contact layer of different plastic films using coating rods providing thickness of 6, 40, 60, and 100 μm. The polyethylene films before and after treatment were analysed by atomic force microscopy (AFM). NS was active against Gram-positive bacteria and the best activity was obtained against Brochothrix thermosphacta. Viable staining and epifluorescence microscopy analysis of indicator strains in contact with activated plastic films showed that the effect of the film on the various indicator strains changed very much on the basis of both type of film and indicator strain. The highest numbers of lysed cells were shown by two polyethylene films that, according to the AFM and roughness parameters analyses, were characterized by significant increase or decrease of roughness after the coating treatment. AFM analysis showed that the homogeneity of the coating was much influenced by the type of plastic films used. In order to test the efficacy in food, portions of beef chuck tender slices were prepared and covered with the antimicrobial plastic films on both sides. After 1 h and 1, 7, and 12 days of storage at 4 °C the meat samples were analyzed by standard plate counting targeting spoilage associated microbial populations. The antimicrobial plastic films after 1 h of contact with the meat caused a significant reduction of lactic acid bacteria and B. thermosphacta. The most effective antimicrobial activity of films was shown against the same populations after 24 h of storage.