Directed inorganic modification of bi-component polymer fibers by selective vapor reaction and atomic layer deposition

Nanocomposite organic/inorganic materials with spatially-controlled composition can be formed using vapor-phase atomic layer deposition (ALD) on bi-component polymer fibers. The ALD process promotes selective precursor infusion into the inner core of a core/shell polymer fiber, yielding nanoparticles encapsulated within the core. Likewise, choosing alternate precursors or reaction conditions yield particles or films on the outer polymer shell. In-situ infrared spectroscopy and transmission electron microscopy show that infusion yields selective dispersion of aluminum oxide in different polymer regions, forming fine nanoparticle dispersions or films. Selective inclusion of metal oxide materials during atomic layer deposition on polymers can create unique organic/inorganic composite structures for many advanced uses.     

Mixing of low-dose cohesive drug and overcoming of pre-blending step using a new gentle-wing high-shear mixer granulator

The objective of this study was to examine the influence of drug amount and mixing time on the homogeneity and content uniformity of a low-dose drug formulation during the dry mixing step using a new gentle-wing high-shear mixer. Moreover, the study investigated the influence of drug incorporation mode on the content uniformity of tablets manufactured by different methods. Albuterol sulfate was selected as a model drug and was blended with the other excipients at two different levels, 1% w/w and 5% w/w at impeller speed of 300?rpm and chopper speed of 3000?rpm for 30?min. Utilizing a 1?ml unit side-sampling thief probe, triplicate samples were taken from nine different positions in the mixer bowl at selected time points. Two methods were used for manufacturing of tablets, direct compression and wet granulation. The produced tablets were sampled at the beginning, middle, and end of the compression cycle. An analysis of variance analysis indicated the significant effect (p?相似文献   

Specifying the Optimal Transmission Manner in WSNs: Analysis and Simulation

Wireless Personal Communications - Employing multi-hop transmission (MH) in wireless sensor networks achieves the uniform distribution of energy cost between nodes. However, the minimum energy cost...     

Experimental and theoretical investigations of the adhesion time of Penicillium spores to cedar wood surface

In this study, the adhesion of 4 Penicillium strains (Penicillium granulatum, Penicillium crustosum, Penicillium commune and Penicillium chrysogenum) on cedar wood was examined qualitatively and quantitatively by using the extended DLVO (XDLVO) approach and the environmental scanning electronic microscopy (ESEM) technique. A comparison between the XDLVO theories and the ESEM technique was also investigated. The adhesion tests revealed that P. chrysogenum was not able to adhere on the cedar wood substrata, as predicted by the XDLVO approach. We have also found by ESEM that the three Penicillium strains (P. granulatum, P. crustosum, P. commune) adhered on wood, as not predicted theoretically.Moreover, the time of adhesion (3 h and 24 h) was used not only to compare the capacity of adhesion according to contact time but also to explain the discrepancies between the XDLVO approach prediction and the adhesion experiments. A positive relationship between the XDLVO approach and adhesion experiments has been observed after 3 h of adhesion. In contrast, a contradiction between the XDLVO predictions and the adhesion test results has been noted after 24 h of adhesion of Penicillium strains to the wood surface.     

CFD and experimental investigation of the gas–liquid flow in the distributor of a compact heat exchanger

High performance of compact heat exchangers is conditioned by correct fluid distribution. This is especially true for gas–liquid heat exchangers where a uniform distribution is particularly delicate to obtain and where maldistribution entails significant performance deterioration. Several phenomena can lead to phase distribution problems: the fins may be subject to manufacturing defects or fouling, leading to shortcuts or dead zones. But the first source of maldistribution may be a poor distribution at the outlet of the entrance distributor. This distributor aims at mixing the phases and distributing them across the channels.     

Cooperative Q‐learning techniques for distributed online power allocation in femtocell networks

In this paper, we address the problem of distributed interference management of femtocells that share the same frequency band with macrocells using distributed multi‐agent Q‐learning. We formulate and solve two problems representing two different Q‐learning algorithms, namely, femto‐based distributed and sub‐carrier‐based distributed power controls using Q‐learning (FBDPC‐Q and SBDPC‐Q). FBDPC‐Q is a multi‐agent algorithm that works on a global basis, for example, deals with the aggregate macrocell and femtocell capacities. Its complexity increases exponentially with the number of sub‐carriers in the system. Also, it does not take into consideration the sub‐carrier macrocell capacity as a constraint. To overcome these problems, SBDPC‐Q is proposed, which is a multi‐agent algorithm that works on a sub‐carrier basis, for example, sub‐carrier macrocell and femtocell capacities. Each of FBDPC‐Q and SBDPC‐Q works in three different learning paradigms: independent (IL), cooperative (CL), and weighted cooperative (WCL). IL is considered the simplest form for applying Q‐learning in multi‐agent scenarios, where all the femtocells learn independently. CL and WCL are the proposed schemes in which femtocells share partial information during the learning process in order to strike a balance between practical relevance and performance. We prove the convergence of the CL paradigm when used in the FBDPC‐Q algorithm. We show via simulations that the CL paradigm outperforms the IL paradigm in terms of the aggregate femtocell capacity, especially in networks with large number of femtocells and large number of power levels. In addition, we propose WCL to address the CL limitations. Finally, we evaluate the robustness and scalability of both FBDPC‐Q and SBDPC‐Q, against several typical dynamics of plausible wireless scenarios (fading, path loss, random activity of femtocells, etc.). We show that the CL paradigm is the most scalable to large number of femtocells and robust to the network dynamics compared with the IL and WCL paradigms. Copyright © 2014 John Wiley & Sons, Ltd.     

Miscibility enhancement of poly(vinyl chloride)/polystyrene blend: Application to membrane separation of benzene from benzene/cyclohexane mixture by pervaporation

In order to improve the miscibility of poly(vinyl chloride)/polystyrene (PVC/PS) system and to use the prepared material as a membrane to separate benzene from benzene/cyclohexane mixture by pervaporation technique, two poly(styrene-co-N-vinylpyrrolidone) (PSVP) copolymers containing 6.67 and 13.55 mol% of N-vinylpyrrolidone (N-VP) contents were synthesized through a radical polymerization. A comparative study of the miscibility of the PVC/PSVP blends with different compositions was carried out using differential scanning calorimetry, viscosimetry and Fourier transform infrared spectroscopy methods in which the interaction parameters between the two components were widely investigated. To improve the pervaporative flux of PVC membrane to separate benzene from benzene/cyclohexane mixture, a preliminary test of swelling and sorption was performed on PVC/PSVP7 membranes using an azeotropic benzene/cyclohexane mixture. It was revealed that the PVC/PSVP7 membrane containing 10 wt% of PSVP7 showed the best performance and the diffusion behaviour of this mixture through PVC and PVC/PCVP7 membranes has a Fickian behaviour. The pervaporation parameters of this membrane support those of the swelling and selective sorption data and reveal that this membrane could enhance the total flux without significantly affecting its selectivity to benzene.