Poly (N‐isopropylacrylamide) (pNIPAm)‐based microgels undergo a transition from fully water swollen (solvated) to deswollen (desolvated) as the temperature of the water they are dissolved in is increased >32 °C. In this submission, we examine how the temperature of this transition, i.e., the volume phase transition temperature (VPTT), depends on the concentration of methanol (MeOH) in water the microgels are dissolved in. To accomplish this, pNIPAm‐based etalons are utilized, and it is shown that the VPTT for the microgels is much less than that previously observed for linear pNIPAm and pNIPAm‐based microgels. Furthermore, and most interestingly, it is determined that the microgels can collapse in solutions containing high MeOH (>∼65% MeOH) concentration. This is in contrast to previous studies, which show that no VPTT is observed for pNIPAm in aqueous solutions containing >∼65% MeOH.
A detailed comparative study of the dielectric and electro-optical properties of a ferroelectric liquid crystal (FLC) and
FLC after having doped with conducting polymer Poly (3,4-ethylenedioxythiophene) (PEDOT) nanotubes is done. The electro-optic
study reveals a lower electrical response time, rotational viscosity and spontaneous polarization in the FLC/PEDOT nanocomposite
system. By fitting the capacitance with voltage in a Preisach model, four dipolar species in both FLC and composites system
have been obtained. The orientation of the four dipolar species in the composites system is such that the effective dipole
moment in the transverse direction of the FLC molecule is less than that in FLC compound. 相似文献
Natural convection boundary layer laminar flow from a horizontal circular cylinder with uniform heat flux in presence of heat generation has been investigated. The governing boundary layer equations are transformed into a non-dimensional form and the resulting non-linear systems of partial differential equations, which are solved numerically by two distinct methods namely: (i) implicit finite difference method together with the Keller-box scheme and (ii) perturbation solution technique. The results of the surface shear stress in terms of local skin-friction and the rate of heat transfer in terms of local Nusselt number, velocity distribution, velocity vectors, temperature distribution as well as streamlines, isotherms and isolines of pressure are shown by graphically for a selection of parameter set consisting of heat generation parameter. 相似文献
The preparation and properties of copper(II) complexes of 4-methoxy-2-(4-methoxy-3-methyl-pyrazol-1-yl)-6-methylpyrimidine, are reported. Complexes of 相似文献
Optical sensors for environmental humidity have been constructed from poly (N-isopropylacrylamide)-co-acrylic acid (pNIPAm-co-AAc) microgels. The devices were constructed by first depositing a monolithic layer of pNIPAm-co-AAc microgels on a Au-coated glass substrate followed by the addition of another Au layer on top. The resultant assembly showed visual color, and exhibited multipeak reflectance spectra. We found that the thickness of the device's microgel layer depended on environmental humidity, which corresponded to a change in the device's optical properties. Specifically, at low humidity the microgel layer was collapsed, while it absorbed water from the atmosphere (and swelled) as the humidity increased. Additionally, we investigated how the deposition of the hygroscopic polymer poly (diallyldimethylammonium chloride) (pDADMAC) onto the microgel layer (prior to final Au layer deposition) influenced the devices humidity response. We found that the devices were more sensitive to humidity as the number of pDADMAC layers in the device increased. Finally, we evaluated the device performance at various temperatures, and found that the sensitivity was enhanced at low temperature, although the response was more linear at elevated temperature. 相似文献
In this paper we investigate multilevel programming problems with multiple followers in each hierarchical decision level. It is known that such type of problems are highly non-convex and hard to solve. A solution algorithm have been proposed by reformulating the given multilevel program with multiple followers at each level that share common resources into its equivalent multilevel program having single follower at each decision level. Even though, the reformulated multilevel optimization problem may contain non-convex terms at the objective functions at each level of the decision hierarchy, we applied multi-parametric branch-and-bound algorithm to solve the resulting problem that has polyhedral constraints. The solution procedure is implemented and tested for a variety of illustrative examples. 相似文献
Two new proteins of approximately 70 amino acids in length, corresponding to an unnaturally-linked N- and C-helix of the ectodomain
of the gp41 protein from the human immunodeficiency virus (HIV) type 1, were designed and characterized. A designed tripeptide
links the C-terminus of the C-helix with the N-terminus of the N-helix in a circular permutation so that the C-helix precedes
the N-helix in sequence. In addition to the artificial peptide linkage, the C-helix is truncated at its N-terminus to expose
a region of the N-helix known as the “Trp-Trp-Ile” binding pocket. Sedimentation, crystallographic, and nuclear magnetic resonance
studies confirmed that the protein had the desired trimeric structure with an unoccupied binding site. Spectroscopic and centrifugation
studies demonstrated that the engineered protein had ligand binding characteristics similar to previously reported constructs.
Unlike previous constructs which expose additional, shallow, non-conserved, and undesired binding pockets, only the single
deep and conserved Trp-Trp-Ile pocket is exposed in the proteins of this study. This engineered version of gp41 protein will
be potentially useful in research programs aimed at discovery of new drugs for therapy of HIV-infection in humans. 相似文献
The design of a computer-aided system for identifying the seizure onset zone (SOZ) from interictal and ictal electroencephalograms (EEGs) is desired by epileptologists. This study aims to introduce the statistical features of high-frequency components (HFCs) in interictal intracranial electroencephalograms (iEEGs) to identify the possible seizure onset zone (SOZ) channels. It is known that the activity of HFCs in interictal iEEGs, including ripple and fast ripple bands, is associated with epileptic seizures. This paper proposes to decompose multi-channel interictal iEEG signals into a number of subbands. For every 20 s segment, twelve features are computed from each subband. A mutual information (MI)-based method with grid search was applied to select the most prominent bands and features. A gradient-boosting decision tree-based algorithm called LightGBM was used to score each segment of the channels and these were averaged together to achieve a final score for each channel. The possible SOZ channels were localized based on the higher value channels. The experimental results with eleven epilepsy patients were tested to observe the efficiency of the proposed design compared to the state-of-the-art methods. 相似文献
Different crosslinked polystyrene resins containing ionic liquid fragments covalently attached (supported ionic liquid-like phases: SILLPs) have been prepared and their conductivity has been studied by means of dielectric impedance spectroscopy. The main structural parameters considered in this study have been the presence of C2H bonds in the imidazolium subunits and the nature (level of hydrophobicity) of the N-substituents (methyl vs. butyl). The results obtained show that the presence of C2H fragments can have an influence on intrinsic conductivity. In the same way the role of the hydrophobicity of the N-substituents seems to play only a minor role. The main structural component associated with conductivity is the nature of the counteranion. The bulkiest, less coordinating anions, in particular the NTf2? anion, seem to be associated with the highest conductivities, with the values obtained being two orders of magnitude higher than those calculated for the same systems containing the Cl? anions for each of the temperatures under study. The results obtained rule out the participation of some given conduction mechanisms such as the involvement of carbene formation. Instead, the formation of ion-pairs of higher or lower association (strong/weak ion pairs) could be responsible for the observed behavior. 相似文献