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111.
The study investigates the effects of the roughness of the metal counterface (mirror finished or polished) on the coefficient of dry friction for some of the most common engineering plastics used in current bearing technology. The results show that an optimal roughness for minimum friction is likely to exist for any polymer, and it depends on the bulk properties of the polymer itself. “Soft” plastics characterized by a low modulus of elasticity exhibit better sliding behaviour on very smooth, mirror finished surfaces, whereas for high-modulus plastics lower friction is measured in combination with rougher, polished counterfaces. The influence of the contact pressure and sliding velocity are also investigated and found to depend on the layout of the tribological system. 相似文献
112.
This paper presents an electronic system for a fast DNA label-less detection. The sensitivity of the capacitive sensor in use is improved by depositing an insulating self-assembled monolayer (SAM) over the golden electrodes. The capacitance shift due to the hybridization effect is monitored by means of a charge-sensitive amplifier and digitalized by means of a comparator and a counter. The read-out solution demonstrates the ability to identify a 0.01% variation on the capacitive value of the sensor. Results from measurements with the optimized sensor show the reliability of the electronics. The investigated solution is suitable for monolithic systems or for a micro-fabricated array of sensors. An example of the integrated front-end is described and performances and noise evaluation are reported here. 相似文献
113.
Daniele Viciani Lorella Dell’Olmo Antonio Gabellini Daniela Gigante Lorenzo Lastrucci 《Landscape Research》2018,43(7):952-964
Widespread trends of abandonment have strongly affected Mediterranean mountains after the Second World War, triggering spontaneous recolonisation of forests. A diachronic analysis of the landscape in a Natura 2000 site (Tuscany, Italy) was carried out using digital aerial photographs (1954, 2013) and a GIS-based methodology, focusing on territories above 1300 m a.s.l. The detected variations of total areas, patch shape, patch dimensions and selected metrics showed a notable shift of the vegetation towards woody types and a drastic reduction of open grasslands, some with high conservation value, accompanied by a strong increase in patch number, surface and edge. A decrease of SDI and SEI diversity indices was also observed. Considering that fragmentation is one of the main causes threatening habitats and species, our results point out a clear necessity for a monitoring programme and suitable actions aimed at improving the status of biodiversity-rich montane grasslands. 相似文献
114.
Isabella Panfoli Daniela Calzia Silvia Ravera Paolo Bianchini Alberto Diaspro 《Microscopy research and technique》2010,73(12):1086-1090
We describe a procedure for the labeling of membranous vesicular purified subcellular fractions, to image them, typically by confocal laser scanning microscopy. Being intracellular organelles, these fractions, once purified cannot be attached to glass slides as for cells. Fractions are labeled “in batch” without prior embedding or freezing. Each labeling step performed by passages of resuspension/centrifugation is followed by washings. Then samples are dispersed on the glass slides. Mammalian retinal rod outer segment disks, intact brain stem myelin vesicles, and brain synaptosomes were chosen, as these subcellular fractions can be purified by well established procedures. These fractions were immunolabeled with specific antibodies. Moreover, by the earlier procedure, we show that the mitochondrial vital membrane potential probe MitoTracker Deep Red 633 stains myelin vesicles and rod disks before fixation, consistently with our previous reports of a respiring capacity of these membranes. Therefore, the technique seems adequate to become an instrument to study the structure and the function of these and other subcellular fractions. Microsc. Res. Tech. 73:1086–1090, 2010. © 2010 Wiley‐Liss, Inc. 相似文献
115.
Daniela Erriquez Giovanni Perini Alessandra Ferlini 《International journal of molecular sciences》2013,14(10):19681-19704
ncRNAs are the most recently identified class of regulatory RNAs with vital functions in gene expression regulation and cell development. Among the variety of roles they play, their involvement in human diseases has opened new avenues of research towards the discovery and development of novel therapeutic approaches. Important data come from the field of hereditary muscle dystrophies, like Duchenne muscle dystrophy and Myotonic dystrophies, rare diseases affecting 1 in 7000–15,000 newborns and is characterized by severe to mild muscle weakness associated with cardiac involvement. Novel therapeutic approaches are now ongoing for these diseases, also based on splicing modulation. In this review we provide an overview about ncRNAs and their behavior in muscular dystrophy and explore their links with diagnosis, prognosis and treatments, highlighting the role of regulatory RNAs in these pathologies. 相似文献
116.
Daniela F. Olivera Viviana O. Salvadori 《International Journal of Food Science & Technology》2011,46(7):1445-1454
Food consumption patterns have changed significantly during the last years, showing an increase in the consumption of convenience foods. Frozen foods represent an important segment of this market. The aim of the present paper was to study the influence of frozen storage on the quality of cooked organic tagliatelle. Instrumental measurements of different quality parameters (moisture content, colour, textural and rheological characteristics of frozen cooked pasta) were performed during twelve months of storage. The sensory properties of pasta were also evaluated by means of an acceptability study. In general, both instrumental and sensory analysis found that frozen storage affects negatively the acceptability of cooked pasta. The advantages obtained through fast freezing procedures are not maintained along storage, being hardness (instrumental) and consistency (sensory) the most relevant quality indices. Finally, the shelf life of the product was calculated as 3.6 and 3.8 months in the cryogenic device and air‐blast tunnel, respectively, based on simple kinetic models. 相似文献
117.
Potentilla erecta (L.) is known for the high concentration of proanthocyanidin oligomers (PAs) in its underground parts. The use of its preparations as food supplements and the lack of chemical–analytical studies concerning with an efficient chromatographic separation procedure for these compounds led us to develop a strategy to profile PAs occurring in this species. 相似文献
118.
119.
In this work, we developed molecular tools used in standard laboratory yeast strains, such as the cre–loxP system, so that they can be used with natural and industrial prototrophic yeast species. We constructed a new generation of dominant cassettes, with mutated loxP sites (loxLE and lox2272) and selectable drug markers, to create heterothallic strains and auxotrophic mutants without incurring in the risk of generating chromosomal rearrangements. We have shown that our newly developed loxLE–hphNT1–loxRE and lox2272–natNT2–lox2272 gene‐disruption cassettes can be present in the yeast genome together with the widely used loxP–marker gene–loxP cassettes without any recombination between the lox sequences. Moreover, we also developed a new phleomycin‐resistant Cre‐expressing vector (to excise multiple markers simultaneously) and two new standard loxP deletion cassettes containing hygromicin B and cloNAT as selecatable markers. To validate these cassettes, we created heterothallic auxotrophic S. cerevisiae strains, without the risk of incurring gross chromosomal rearrangements, and we showed an example of a fitness study of intraspecific hybrids deriving from parents with different adaptations to carbon‐limited resources. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
120.
Fiber introduction mass spectrometry: fully direct coupling of solid-phase microextraction with mass spectrometry 总被引:1,自引:0,他引:1
This work describes the first fully direct coupling of solid-phase microextraction (SPME) with mass spectrometry. An inlet system using a septum as the only interface between the ambient and the high-vacuum mass spectrometer was constructed to allow the introduction of the SPME needle directly into the ionization region of a mass spectrometer. The PDMS-coated fiber was then placed and exposed exactly between the two ionization filaments. Uniform heating of the fiber, efficient thermal desorption, and electron ionization of the analytes were achieved. Using this new analytical technique, here termed fiber introduction mass spectrometry (FIMS), we have been able to detect and quantitate several volatile (VOC) and semivolatile (SVOC) organic chemicals (carbon tetrachloride, benzene, toluene, xylenes, gamma-terpinene, diisoamyl ether, chlorobenzene, and many PAHs) and two herbicides (Sylvex and its methyl ether) from aqueous solutions at low-ppb to ppt levels using either SPME headspace or solution extraction. FIMS shows high sensitivity (ng/L), good reproducibility, and accuracy, providing therefore a simple and effective approach to rapid analysis of VOC and SVOC in various matrixes. 相似文献