排序方式: 共有192条查询结果,搜索用时 15 毫秒
51.
A new nematic-like mesophase photoconductive polymer PPT-TPA consisting of wholly aromatic rigid backbone of poly(p-phenyleneterephthalate), PPT and pendent hole-transporting triphenylamine (TPA) groups attached to the ends of oxydecyl spacers has been synthesized. The photorefractive composite contains the photoconductor PPT-TPA, the chromophore diethylaminodicyanostyrene (DDCST), and the photosensitizer C60. Although no plasticizer was added, the glass transition temperature Tg of the composite is 15 °C, which characterizes it as a low-Tg photorefractive material. We investigate the correlation between the mesophase structure and its optical/physical properties by X-ray diffraction, photoconductive and photorefractive experiments. The new composite and its properties are compared to PPT-CZ composites with only a different charge transporting agent (carbazole, CZ) but a much more ordered mesophase structure, which were studied previously and have shown very good photorefractive properties. Despite of a lower photoconductivity of the new photorefractive composite PPT-TPA (n=10):DDCST:C60 this material shows a higher photorefractive sensitivity Sn2 of 2±0.2 cm2/kJ at E=50 V/μm than the previously synthesized composite PPT-CZ (n=10):DDCST:C60. 相似文献
52.
Optical Crystals: Benzothiazolium Single Crystals: A New Class of Nonlinear Optical Crystals with Efficient THz Wave Generation (Adv. Mater. 30/2017) 下载免费PDF全文
53.
Mojca Pavlin Jasna Lojk Klemen Strojan Iva Hafner-Bratkovi
Roman Jerala Adrijana Leonardi Igor Kriaj Nataa Drnovek Saa Novak Peter Verani
Vladimir Botjan Bregar 《International journal of molecular sciences》2022,23(11)
Alongside physiochemical properties (PCP), it has been suggested that the protein corona of nanoparticles (NPs) plays a crucial role in the response of immune cells to NPs. However, due to the great variety of NPs, target cells, and exposure protocols, there is still no clear relationship between PCP, protein corona composition, and the immunotoxicity of NPs. In this study, we correlated PCP and the protein corona composition of NPs to the THP-1 macrophage response, focusing on selected toxicological endpoints: cell viability, reactive oxygen species (ROS), and cytokine secretion. We analyzed seven commonly used engineered NPs (SiO2, silver, and TiO2) and magnetic NPs. We show that with the exception of silver NPs, all of the tested TiO2 types and SiO2 exhibited moderate toxicities and a transient inflammatory response that was observed as an increase in ROS, IL-8, and/or IL-1β cytokine secretion. We observed a strong correlation between the size of the NPs in media and IL-1β secretion. The induction of IL-1β secretion was completely blunted in NLR family pyrin domain containing 3 (NLRP3) knockout THP-1 cells, indicating activation of the inflammasome. The correlations analysis also implicated the association of specific NP corona proteins with the induction of cytokine secretion. This study provides new insights toward a better understanding of the relationships between PCP, protein corona, and the inflammatory response of macrophages for different engineered NPs, to which we are exposed on a daily basis. 相似文献
54.
Petr Žáček Blanka Kalinová Jan Šobotník Oldřich Hovorka Vladimír Ptáček Audrey Coppée François Verheggen Irena Valterová 《Journal of chemical ecology》2009,35(6):698-705
Age-related changes of antennal-active components of male labial gland extracts were studied in two closely related bumblebee
species, Bombus terrestris and B. lucorum. In B. terrestris, compounds eliciting electroantennogram (EAG) responses of virgin queens were ethyl dodecanoate, 2,3-dihydrofarnesal, 2,3-dihydrofarnesol,
hexadecan-1-ol, octadeca-9,12,15-trien-1-ol, and geranylcitronellol. Compounds that elicited EAG responses from queens of
B. lucorum were ethyl dodecanoate, ethyl tetradec-7-enoate, ethyl tetradec-9-enoate, ethyl hexadec-9-enoate, hexadecan-1-ol, hexadec-7-enal,
octadeca-9,12-dien-1-ol, octadeca-9,12,15-trien-1-ol, and octadecan-1-ol. Quantities of these compounds in the labial glands
changed significantly over the lifetime of the respective males of the two species. In both species, concentrations of the respective compounds reached their maximum within seven days after eclosion. Subsequently,
a rapid decrease in the amount of EAG-active compounds occurred in B. terrestris, whereas in B. lucorum the amount of active compounds stayed approximately constant or decreased at a slow rate. Microscopy showed that in B. terrestris secretory cells of the labial glands undergo apoptosis from the fifth to the tenth day of life, whilst in B. lucorum labial gland cells remain unchanged throughout the life of the males. 相似文献
55.
Stefaan Mys Jürgen Slowack Jozef Škorupa Nikos Deligiannis Peter Lambert Adrian Munteanu Rik Van de Walle 《Multimedia Tools and Applications》2012,58(1):239-266
Distributed Video Coding (DVC) is a video coding paradigm in which the computational complexity is shifted from the encoder
to the decoder. DVC is based on information theoretic results suggesting that, under ideal conditions, the same rate-distortion
performance can be achieved as for traditional video codecs. In practice however, there is still a significant performance
gap between the two coding architectures. One of the main reasons for this gap is the lack of multiple coding modes in current
DVC solutions. In this paper, we propose a block-based distributed video codec that supports three coding modes: Wyner–Ziv,
skip, and intra. The mode decision process is entirely decoder-driven. Skip blocks are selected based on the estimated accuracy
of the side information. The choice between intra and Wyner–Ziv coding modes is made on a rate-distortion basis, by selecting
the coding mode with the lowest rate while assuring equal distortion for both modes. Experimental results illustrate that
the proposed block-based architecture has some advantages over classical bitplane-based approaches. Introducing skip and intra
coded blocks yields average bitrate gains of up to 33.7% over our basic configuration supporting Wyner–Ziv mode only, and
up to 29.7% over the reference bitplane-based DISCOVER codec. 相似文献
56.
Jiří Hrdlička Petr Červenka Michal Přibyl Dalimil Šnita 《Journal of Applied Electrochemistry》2010,40(5):967-980
AC electroosmotic micropumps are suggested to be powerful tools for electrolyte dosing in various micro- and nanofluidic systems. In this paper, we compare two modeling approaches for studying the AC electroosmosis in the following micro and nanochannel systems: (i) a traveling-wave AC pump with a spatially continuous wave of electric potential applied on a planar boundary, (ii) a traveling-wave AC pump with a wave of electric potential applied on a set of discrete planar electrodes, and (iii) an AC pump with a set of non-planar electrodes. The equilibrium approach is based on the use of capacitor–resistor boundary conditions for electric potential and the slip boundary conditions for velocity at electrode surfaces. The non-equilibrium approach uses the mathematical model based on the Poisson equation and the non-slip boundary conditions. We have observed discrepancies between the predictions given by the both models and then we have identified their possible reasons. The comparison of the equilibrium and non-equilibrium results further showed three important actualities: (a) how the equilibrium model overestimates or underestimates the net velocity, (b) how the velocity maxima in the frequency characteristics can be shifted, if the equilibrium model assumptions are not satisfied, (c) the parametric region where the equilibrium model is applicable. Because the data are obtained in a dimensionless form, they can be exploited for AC electroosmotic studies. We discuss the limitations of the equilibrium and non-equilibrium models and compare selected predictions with available experimental data. 相似文献
57.
L’udovít Kubičár Viliam Vretenár Vladimír Štofanik Vlastimil Boháč 《International Journal of Thermophysics》2010,31(10):1904-1918
This article deals with the theory and performance of a sensor for measuring thermal conductivity. The sensor, in the form
of a small ball, generates heat and simultaneously measures its temperature response. An ideal model of the hollow sphere
in an infinite medium furnishes a working equation of the hot-ball method. A constant heat flux through the surface of the
ball generates the temperature field. The thermal conductivity of the surrounding medium is to be determined by the stabilized
value of the temperature response, i.e., when the steady-state regime is attained. Error components of the sensor are discussed
due to analysis of the deviations of the real hot-ball construction from the ideal model. The functionality of a set of hot
balls has been tested, and the calibration for a limited range of thermal conductivities was performed. A working range of
thermal conductivities of tested materials has been estimated to be from 0.06 W· m−1 · K−1 up to 1 W· m−1 · K−1. 相似文献
58.
Soy protein isolate (SPI) films plasticized with different contents of short and linear glycerol (G) and hyperbranched dendritic polyglycerol (DPG) in the presence of water were prepared for the first time with kneading and compression molding; these were analyzed in relation to their visual, morphological, microstructural, mechanical, and water‐ and oxygen‐barrier properties. It was shown that the film prepared with a mixture of 15G15DPG (where the numbers represent the weight percentage of the respective compound) had a higher tensile strength (∼14.4%), lower elongation at break (∼85.7%), and improved water‐barrier (∼54.6%) and oxygen‐barrier (∼84.1%) properties compared to the SPI film plasticized only with 30G. The attenuated total reflectance–Fourier transform infrared spectra of the plasticized SPI films indicated that such properties were related to the approximately 11.3% higher conversion of SPI from the α‐helical conformation to the intramolecular β‐sheet structures for the 15G15DPG films. This resulted in finer films with lower surface roughnesses and surface areas. On the other hand, further increases in G and DPG revealed an opposite effect and worsened the properties; this was much more pronounced by the increased DPG amount because of SPI unfolding and aggregation and resulted in microporous films. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41837. 相似文献
59.
Two mathematical models, Sanchez–Lacombe equation of state and the Perturbed-Chain Statistical Associating Fluid Theory were applied for modelling the phase equilibrium for the poly(l-lactide)–CO2 and poly(d,l-lactide-co-glycolide)–CO2 systems. Aspen Polymer Plus software was used. The results were compared with previously obtained experimental values for solubility. The solubility of scCO2 in the two biodegradable polymers was calculated for three different temperatures (308, 313 and 323 K) in the pressure range (10–30 MPa). The characteristic parameters for the components and the binary interaction parameters for the models were optimized in order to obtain the best fit between the estimated and the experimental gas solubility data. The results suggest that both SL EOS and PC-SAFT are reliable models in describing the phase equilibrium of the PLLA–CO2 and PLGA–CO2 systems at the proposed working conditions. 相似文献
60.
Matej Zadravec Matjaž Hriberšek Leopold Škerget 《Engineering Analysis with Boundary Elements》2009,33(4):485-492
The contribution deals with numerical simulation of natural convection in micropolar fluids, describing flow of suspensions with rigid and underformable particles with own rotation. The micropolar fluid flow theory is incorporated into the framework of a velocity–vorticity formulation of Navier–Stokes equations. The governing equations are derived in differential and integral form, resulting from the application of a boundary element method (BEM). In integral transformations, the diffusion-convection fundamental solution for flow kinetics, including vorticity transport, heat transport and microrotation transport, is implemented. The natural convection test case is the benchmark case of natural convection in a square cavity, and computations are performed for Rayleigh number values up to 107. The results show, which microrotation of particles in suspension in general decreases overall heat transfer from the heated wall and should not therefore be neglected when computing heat and fluid flow of micropolar fluids. 相似文献