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11.
Martin Parizek Nikola Kasalkova Lucie Bacakova Petr Slepicka Vera Lisa Martina Blazkova Vaclav Svorcik 《International journal of molecular sciences》2009,10(10):4352-4374
High-density polyethylene (PE) foils were modified by an Ar+ plasma discharge and subsequent grafting with biomolecules, namely glycine (Gly), polyethylene glycol (PEG), bovine serum albumin (BSA), colloidal carbon particles (C) or BSA and C (BSA + C). As revealed by atomic force microscopy (AFM), goniometry and Rutherford Backscattering Spectroscopy (RBS), the surface chemical structure and surface morphology of PE changed dramatically after plasma treatment. The contact angle decreased for the samples treated by plasma, mainly in relation to the formation of oxygen structures during plasma irradiation. A further decrease in the contact angle was obvious after glycine and PEG grafting. The increase in oxygen concentration after glycine and PEG grafting proved that the two molecules were chemically linked to the plasma-activated surface. Plasma treatment led to ablation of the PE surface layer, thus the surface morphology was changed and the surface roughness was increased. The materials were then seeded with vascular smooth muscle cells (VSMC) derived from rat aorta and incubated in a DMEM medium with fetal bovine serum. Generally, the cells adhered and grew better on modified rather than on unmodified PE samples. Immunofluorescence showed that focal adhesion plaques containing talin, vinculin and paxillin were most apparent in cells on PE grafted with PEG or BSA + C, and the fibres containing α-actin, β-actin or SM1 and SM2 myosins were thicker, more numerous and more brightly stained in the cells on all modified PE samples than on pristine PE. An enzyme-linked immunosorbent assay (ELISA) revealed increased concentrations of focal adhesion proteins talin and vinculin and also a cytoskeletal protein β-actin in cells on PE modified with BSA + C. A contractile protein α-actin was increased in cells on PE grafted with PEG or Gly. These results showed that PE activated with plasma and subsequently grafted with bioactive molecules and colloidal C particles, especially with PEG and BSA + C, promotes the adhesion, proliferation and phenotypic maturation of VSMC. 相似文献
12.
Vaclav Dolezal 《Circuits, Systems, and Signal Processing》1997,16(6):655-661
In the stability and sensitivity theory of general, nonlinear input-output systems we encounter a certain inequality concerning solely the nominal system that plays a central role in the whole theory. In particular, this central inequality, combined with other assumptions, implies (a) stability of the nominal system, (b) robustness, and (c) insensitivity of the input-output system. This paper presents conditions equivalent to this central inequality, and a further result on the stability-robustness problem. 相似文献
13.
Petra Chocholata Vlastimil Kulda Jana Dvorakova Monika Supova Margit Zaloudkova Vaclav Babuska 《International journal of molecular sciences》2021,22(17)
Bone tissue engineering tries to simulate natural behavior of hard tissues. This study aimed to produce scaffolds based on polyvinyl alcohol (PVA) and hyaluronic acid (HA) with hydroxyapatite (HAp) incorporated in two different ways, by in situ synthesis and physical mixing of pre-prepared HAp. In situ synthesis resulted in calcium deficient form of HAp with lower crystallinity. The proliferation of human osteoblast-like cells MG-63 proved to be better in the scaffolds with in situ synthesized HAp compared to those with physically mixed pre-prepared HAp. For scaffolds with PVA/HA/HAp ratio 3:1:2, there was significantly higher initial adhesion (p = 0.0440), as well as the proliferation in the following days (p < 0.001). It seemed to be advantageous improve the properties of the scaffold by in situ synthesizing of HAp directly in the organic matrix. 相似文献
14.
A prerequisite for effective pest risk management in food is the unbiased interpretation of results obtained by various detection methods. In this study we compared the sensitivity of filth flotation tests, sieving and heat extraction in Tullgren–Berlese funnels for detecting insect contaminants. Samples of wheat grain, flour and semolina were contaminated with eggs, juveniles and adults of Tribolium castaneum, and eggs or larvae of Ephestia kuehniella. Calibration methods were applied for every detection method, and total and sample recoveries and detection limits were calculated for each method, food substrate and contaminant type. The tested contaminants were not detected on a qualitative level by any single technique, instead a combination of techniques was necessary for detection. Sieving was the method with the highest total recoveries, ranging from 90 to 100%. Filth flotation was a uniquely effective for egg detection, with total recoveries ranging from 65 to 95%. The extraction of adults and larvae of both species in Tullgren–Berlese funnels failed in semolina and flour, and was of very limited success in grain. The detection limits for sieving were from 1 to 16 contaminants/kg commodity. The detection limits for filth flotation were from 224 to 508 eggs, and 58 to 507 adults or larvae/kg commodity. The sample recoveries were usually influenced by sample size, species, stadium and their interactions, and indicated how to optimize method protocols. The calibration of methods provided estimates of contaminant densities different from those obtained without calibration. Our work revealed that some currently used methods are not sensitive enough to detect all stages of insect pests, or in some cases, low levels of pest infestation. This lack of sensitivity potentially enables the infested cereal food product to continue down the food processing chain even after laboratory inspection. 相似文献
15.
Delong Cai Zhihua Yang Jingkun Yuan Xiaoming Duan Shengjin Wang Vaclav Ocelik D.I. Vainchteind J.TH.M. De Hossond Dechang Jia Yu Zhou 《Ceramics International》2018,44(2):1518-1525
In the present study, ablation behavior and properties of BN-MAS (magnesium aluminum silicate) composites impinged with an oxyacetylene flame at temperatures up to 3100 °C were investigated. As ablation time ranged from 5 to 30 s, the mass and linear ablation rates increased from 0.0027 g/s and 0.001 mm/s to 0.0254 g/s and 0.087 mm/s, respectively. A SiO2-rich protective oxide layer formed during the ablation process, which contributed to the oxidation resistance of the composites. Ablation products mainly consisted of magnesium-aluminum borosilicate glass, mullite, spinel and indialite. The thermal oxidation of h-BN during flame ablation and scouring of MAS by high-speed gas flow were the main ablation mechanisms. 相似文献
16.
17.
We consider the problem of finding a maximum subset of a given set of wires connecting two rows of terminals with fixed positions, such that no wires in the subset cross. We derive an algorithm that runs in O(p + (n ? p) ? g(p + 1)) time, where n is the number of wires given and p is the maximum number of noncrossing wires; in many practically relevant cases, e.g., when p is very high, it needs only linear time. We show how an extension of the algorithm solves the more general problem, where the positions of some terminals have some flexibility, within the same time bound. 相似文献
18.
Vaclav Dvorak 《国际水资源开发杂志》1996,12(2):181-192
In terms of climate, the Czech Republic belongs to the northern hemisphere Atlantic-contin ental type of moderate clim ate. M ean annual temperature ranges between 1.0 and 9.4 C (for summer between 8.8 C and 18.5 C, and for winter between - 6.8 and 0.2 C). Annual precipitation ranges between 450 mm in dry regions and 1300 m m in mountainous regions of the country. With its 2000 m 3 per capita fresh water availability, the Czech Republic is a region that can be characterized as slightly below average in availability. The occasional water shortages usually do n ot result from unavailability of water, but rather from temporal or spatial variability of water supply and demand and a high degree of water resources exploitation. To study poten tial im pacts of climate change on the hydrological system and water resources, four river basins have been selected in the territory of the Czech Republic: the Elbe River at De c i n (50762 km 2), the Zelivka River at Soutice (1189 km 2), the Upa River at Ceska Skalice (461 km 2), and the M etuje River at M ars ov n. M . (94 km 2). To simulate poten tial changes in runoff, three hydrological models have been applied using in cremental and GCM (GISS, GFDL and CCCM ) scenarios: the BILAN water balance model, the SACRAM ENTO (SAC-SM A) conceptual model and the CLIRU N water balance m odel. After comparison of the results, the BILAN m odel was selected to serve for subsequent analyses of hydrological systems in the river basins. The paper reviews methods applied in the study and results of the assessments, and it concludes with suggestions for general adaptation policy options where the preference is for non-structural measures such as water conservation, efficient water dem and management and protection of water resources. 相似文献
19.
Vaclav E. Beneš Robert J. Elliott 《Mathematics of Control, Signals, and Systems (MCSS)》1996,9(4):341-351
In risk-sensitive control a modified Zakai equation arises which includes an extra term related to the exponential running
cost. We show that a wide class of finite-dimensional solutions related to the Beneš filter is possible as long as nonlinearities
in the drift are canceled in an appropriate way by terms in the running cost.
The support of NSERC Grant A7964 is gratefully acknowledged. 相似文献
20.
Vaclav Dolezal 《Circuits, Systems, and Signal Processing》1996,15(3):313-333
We construct a general model of a nonlinear input-output system consisting of finitely many blocks whose variables are in extended spaces. This model encompasses all configurations used in control which have several feedback and feedforward loops. We show that such a system is essentially the traditional MI-MO feedback system. Moreover, assuming that one block of the system is a plant affected by perturbations, we derive conditions guaranteeing linear insensitivity and/or robust stability of the whole system. In particular, we consider systems whose variables are continuous, vector-valued functions on [0, ), and whose blocks are described by nonlinear Volterra operators. The applications of the results are illustrated by several examples of feedback-feedforward systems. 相似文献