排序方式: 共有30条查询结果,搜索用时 15 毫秒
1.
The transitions and reactions involved in the thermal processing of binary mixtures of polyethylene and poly(ethylene‐co‐vinyl acetate) copolymers with different concentrations of a foaming agent (azodicarbonamide) were studied using differential scanning calorimetry (DSC). The effect of ZnO as a kicker also was discussed. The temperature at the maximum rate and the heat evolved were measured for all the processes—melting, transitions, and reactions—all the mixtures prepared were measured and compared. Azodicarbonamide decomposed differently depending on the polymeric matrix. These data can be very useful for the plastic processing industry. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2015–2025, 2006 相似文献
2.
Alberto Pla-Lpez Raquel Castillo Rocío Cejudo-Marín Olaya García-Pedrero Mariam Bakir-Laso Eva Falomir Miguel Carda 《International journal of molecular sciences》2022,23(13)
Twenty-six triazole-based derivatives were designed for targeting both PD-L1 (programmed death receptor ligand 1) and VEGFR-2 (vascular endothelial growth factor receptor 2). These compounds were synthetized and biologically evaluated as multitarget inhibitors of VEGFR-2, PD-L1 and c-Myc proteins. The antiproliferative activity of these molecules on several tumor cell lines (HT-29, A-549, and MCF-7) and on the non-tumor cell line HEK-293 was determined. The effects on the abovementioned biological targets were evaluated for some selected compounds. Compound 23, bearing a p-chlorophenyl group, showed better results than sorafenib in regard to the downregulation of VEGFR-2 and a similar effect to BMS-8 on both PD-L1 and c-Myc proteins. The antiangiogenic and antivascular activities of chloro derivatives were also established by endothelial microtube formation assay on Matrigel®. 相似文献
3.
Olaya Ruiz-Rueda Mar?al Soler Laia Calv�� Jes��s L. Garc��a-Gil 《Food Analytical Methods》2011,4(2):131-138
In this study, we have developed a rapid method for the simultaneous detection of Listeria monocytogenes and Salmonella spp. in foods, combining culture enrichment and a multiplex real-time polymerase chain reaction (PCR). The assay used two
pre-existing primer-probe sets, labelled with different reporter dyes to enable the direct distinction of the original contaminating
agent. Amplification efficiency and inclusivity/exclusivity of the combined assay was successfully assessed. The overall process
included the culture enrichment based on the ISO standard, consisting of 24 h incubation in appropriate media (Half Fraser
Broth for Listeria and buffered peptone water (BPW) for Salmonella), followed by a single DNA extraction of mixed enrichment aliquots, and real-time PCR detection of the hly and bipA genes of L. monocytogenes and Salmonella spp., respectively. An internal amplification control, co-amplified during the PCR run, was included in the assay to verify
the results. The tool was evaluated with a variety of artificially inoculated samples of fresh products and ready to eat and
cooked dishes, allowing the identification of the target pathogens down to 5 CFU/25 g of food sample. Moreover, the analysis
saved a considerable amount of time compared to the ISO standard, being performed in less than 2 working days. Specificity,
sensitivity and accuracy were satisfactorily tested by comparison to the standard methods ISO 11290-2:1998 and ISO 6579:2002,
suggesting that the tool has a great potential as a reliable alternative for food safety assurance providing rapid detection
of both pathogens in food samples. 相似文献
4.
This article presents nanohardness, coefficient of friction (COF), and wear of Yttria-stabilized zirconia coatings (YSZ) deposited on 316L steel substrates and co-deposited with Al and Ag. YSZ coatings were deposited via RF sputtering reactive phase technique. It is widely known that the RF sputtering technique produces stoichiometric coatings with high homogeneity and density. The average thickness of the coatings was 200 nm, and the X-ray diffraction study (XRD) showed the formation of alumina alpha (α-Al2O3) and metallic silver in the YSZ coatings deposited with Al and Ag, respectively. The mechanical properties were evaluated by means of nanoindentation, and the wear resistance was studied with pin-on-disk technique. The addition of Ag to the YSZ coatings led to decreased hardness, while the YSZ coatings deposited with Al presented an increased hardness. Finally, YSZ coatings deposited with aluminum and silver had the lowest friction coefficient, while Ag-YSZ coatings had a COF very similar to that obtained in YSZ coatings. The wear resistance test showed that YSZ coatings deposited with Al had lower volume loss compared to YSZ coatings deposited with Ag. The wear mechanism in the deposited coatings is analyzed. 相似文献
5.
Experimental results at 25°C are reported for infinite‐dilution distribution coefficients for 19 nonvolatile solutes between aqueous solution and three kinds of polymer films, and for their diffusion coefficients in the polymer matrix. The experiments were performed by coupling UV spectroscopy and gravimetric measurements with mass balances. The solutes are aromatic nonvolatile compounds that are of interest in environmental technology and may serve as model compounds for drug‐delivery systems. The polymers are ethylene‐vinyl acetate copolymers with 33 (EVAc33) and 45 (EVAc45) weight percentage vinyl acetate, and poly(vinyl acetate) (PVAc) widely used in drug‐delivery devices. For PVAc, a long time is required to reach equilibrium. Because the required time is too long for reasonable experimental studies, equilibrium distribution coefficients were calculated from finite‐time data by using a diffusion model. The contribution of surface adsorption is shown to be negligible. Infinite‐dilution distribution coefficients Ks, defined as the volume fraction of solute in the polymer divided by that in water, tend to increase with vinyl acetate content; they range from near unity to several hundred. Diffusion coefficients, determined from time‐dependent sorption data, are significantly larger in EVAc copolymers (10?10 to 10?8 cm2/s) than in PVAc (10?12 cm2/s). These data may be useful for design of membrane processes, for controlled delivery of drugs, and for application in packaging and storage of food, chemicals, and pharmaceuticals. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2041–2052, 2002 相似文献
6.
7.
Wei J Olaya D Karasik BS Pereverzev SV Sergeev AV Gershenson ME 《Nature nanotechnology》2008,3(8):496-500
The submillimetre or terahertz region of the electromagnetic spectrum contains approximately half of the total luminosity of the Universe and 98% of all the photons emitted since the Big Bang. This radiation is strongly absorbed in the Earth's atmosphere, so space-based terahertz telescopes are crucial for exploring the evolution of the Universe. Thermal emission from the primary mirrors in these telescopes can be reduced below the level of the cosmic background by active cooling, which expands the range of faint objects that can be observed. However, it will also be necessary to develop bolometers-devices for measuring the energy of electromagnetic radiation-with sensitivities that are at least two orders of magnitude better than the present state of the art. To achieve this sensitivity without sacrificing operating speed, two conditions are required. First, the bolometer should be exceptionally well thermally isolated from the environment; second, its heat capacity should be sufficiently small. Here we demonstrate that these goals can be achieved by building a superconducting hot-electron nanobolometer. Its design eliminates the energy exchange between hot electrons and the leads by blocking electron outdiffusion and photon emission. The thermal conductance between hot electrons and the thermal bath, controlled by electron-phonon interactions, becomes very small at low temperatures ( approximately 1 x 10-16 W K-1 at 40 mK). These devices, with a heat capacity of approximately 1 x 10-19 J K-1, are sufficiently sensitive to detect single terahertz photons in submillimetre astronomy and other applications based on quantum calorimetry and photon counting. 相似文献
8.
F. Fornasiero M. M. Olaya I. Wagner F. Brüderle J. M. Prausnitz 《American Institute of Chemical Engineers》2002,48(6):1284-1291
Because there is no simple, general method for measuring solubilities of nonvolatile solutes in a polymer, this work presents a thermodynamic framework for estimating such solubilities from infinite-dilution distribution-coefficient data for aqueous solutions of the solute in equilibrium with the polymer. The experimental infinite-dilution distribution coefficient is related to that calculated from a molecular-thermodynamic model (Flory–Huggins). The three binary Flory parameters are obtained from water–solute and water–polymer data, and from the solute's distribution coefficient. Solubilities of 19 nonvolatile aromatic solutes were estimated in three polymers: ethyl-vinyl acetate copolymer (EVAc) with 33 (EVAc33), 45 (EVAc45) wt. % vinyl acetate content, and poly(vinyl acetate) (PVAc) at 25°C, where most of the solutes are solids. For some of these systems, predicted solubilities are compared with new experimental results. The calculations reported here may be useful for various applications, including the design of membrane processes or drug-delivery systems, and for packaging technology for foods, chemicals, and pharmaceuticals. 相似文献
9.
Ortiz E Alemón E Romero D Arriaga JL Olaya P Guzmán F Rios C 《The Science of the total environment》2002,287(3):241-248
The Mexico City Metropolitan Zone (ZMCM) population's exposure to benzene, toluene and xylene was measured at different microenvironments to establish basic indicators of the presence and effects of these characteristic volatile organic compounds (VOC). In particular, VOC personal exposures were measured in different microenvironments during a 5-day working week, with 12-h daily periods. We have found a good agreement of our results with the registered VOC levels of the Metropolitan Automated Monitor System (RAMA) for the corresponding period. From our results, we expect to generate useful information to evaluate the health effects of these VOCs on exposed people. 相似文献
10.
In this paper we report the mechanical properties of chromium nitride (CrN) thin films deposited at different levels of ion bombardment and their relationship with the microstructural parameters, such as grain size, preferred orientation and residual stress. The samples were deposited by unbalanced magnetron sputtering changing the substrate-target distance and the substrate bias, keeping other deposition condition fixed. The mechanical properties were obtained by nanoindentation performed on 1.8 μm thick samples. Under the different deposition conditions all of the CrN films were approximately stoichiometric, but clear variations in the microstructure were seen. The hardness was nearly constant at 24-27 GPa even when the grain size, residual stress and crystalline orientation changed. However, the elastic modulus showed a steady increase from 300 to 350 GPa, proportional to the variations in grain size and the residual stress level. 相似文献