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111.
This paper investigates theoretical properties of throughput and cost in linear loss networks. The maximum throughput of the
network with exponential service times is derived and the arrival process that maximizes throughput, given a fixed arrival
rate, is established. For general service times, an asymptotically critical loading regime is identified such that the probability
of an arbitrary customer being lost is strictly within (0,1) as the network size increases. This regime delivers throughput
comparable to the maximum at a relatively low network cost. The paper establishes the asymptotic throughput and network cost
under this critical loading. 相似文献
112.
Darka Mihailović Zoran Šaponjić Vesna Vodnik Branislav Potkonjak Petar Jovančić Jovan M. Nedeljković Maja Radetić 《先进技术聚合物》2011,22(12):2244-2249
This study is aimed to highlight the possibility of engineering the multifunctional textile nanocomposite material based on the polyester (PES) fabric modified with colloidal Ag and TiO2 nanoparticles (NPs). The effects of concentration of NPs as well as the order of Ag and TiO2 NPs loading on antimicrobial, UV protective, and photocatalytic properties of PES fabrics were examined. The antimicrobial activity of differently modified PES fabrics was tested against Gram‐negative bacterium Escherichia coli, Gram‐positive bacterium Staphylococcus aureus, and fungus Candida albicans. The concentration of Ag colloid and the order of Ag and TiO2 NPs loading considerably affected the antimicrobial efficiency of PES fabrics. The fabrics provided maximum UV protection upon surface modification with Ag and TiO2 NPs. Ag NPs enhanced Ag NPs enhanced the photodegradation activity of TiO2 NPs and total photodegradation of methylene blue was achieved after 24 hr of UV illumination. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
113.
Local C∞ and (sharp) Gevrey hypoellipticity are proved for maximally hypoelliptic fourth order partial differential operators of the form P = D|c|<4 aa(x)Xa in R" where the independent real vector fields Xj,j<n - l, satisfy the Hörmander condition that at most k brackets of the Xj spans the tangent space at each point. 相似文献
114.
115.
Mariya-Desislava Atanasova Georgy Grancharov Petar D. Petrov 《Journal of polymer science. Part A, Polymer chemistry》2021,59(3):251-260
We report novel micellar carriers, comprising pendant cinnamyl moieties in the core-forming block, designed to increase the solubilization of caffeic acid phenethyl ester (CAPE) in aqueous media. Amphiphilic poly(ethylene oxide)-block-poly(α-cinnamyl-ε-caprolactone-co-ε-caprolactone) (PEO-b-P(CyCL-co-CL) diblock copolymers were synthesized by ring-opening copolymerization of α-propargyl-ε-caprolactone and ε-caprolactone from a monofunctional PEO macroinitiator and subsequent attachment of cinnamyl groups via click reaction. In addition, a linear PEO-b-PCL diblock copolymer was synthesized and used in this study for comparison. Next, nanosized micelles from PEO-b-P(CyCL-co-CL) and PEO-b-PCL were formed via the solvent evaporation method and then loaded with CAPE. Dynamic and electrophoretic light scattering, and transmission electron microscopy were used to characterize both blank and loaded carriers. The potential of the micelles comprising pendant cinnamyl group to solubilize CAPE in water was evaluated in a comparative fashion to that of nonmodified PEO-b-PCL diblock copolymer. 相似文献
116.
117.
Xuan Leng Thanh Nhut Do Parveen Akhtar Hoang Long Nguyen Petar H. Lambrev Howe‐Siang Tan 《化学:亚洲杂志》2020,15(13):1996-2004
We simulated two‐dimensional electronic spectra (2DES) of the chlorophyll a manifold of light‐harvesting complex II (LHCII) at various temperatures (77, 110, 150, 190, 230, 273, and 293 K) using the hierarchical equations of the motion‐phase matching approach. We confirm the main excitation energy transfer pathways assignments within the chlorophyll a manifold of LHCII measured in a recent work (J. Phys. Chem. B 2019, 123, 6765–6775). The calculated transfer rates are also in general agreement with the measured rates. We also provided theoretical confirmation for the experimental assignments, as uphill and downhill energy transfer processes, of 2D spectral features that were reported in recent experimental reports. These temperature‐dependent features were also ascertained to follow the detailed‐balance principle. 相似文献
118.
Ya‐Hao Wang Jia‐Bo Le Wei‐Qiong Li Jie Wei Petar M. Radjenovic Hua Zhang Xiao‐Shun Zhou Jun Cheng Zhong‐Qun Tian Jian‐Feng Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(45):16208-16212
It is vital to understand the oxygen reduction reaction (ORR) mechanism at the molecular level for the rational design and synthesis of high activity fuel‐cell catalysts. Surface enhanced Raman spectroscopy (SERS) is a powerful technique capable of detecting the bond vibrations of surface species in the low wavenumber range, however, using it to probe practical nanocatalysts remains extremely challenging. Herein, shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS) was used to investigate ORR processes on the surface of bimetallic Pt3Co nanocatalyst structures. Direct spectroscopic evidence of *OOH suggests that ORR undergoes an associative mechanism on Pt3Co in both acidic and basic environments. Density functional theory (DFT) calculations show that the weak *O adsorption arise from electronic effect on the Pt3Co surface accounts for enhanced ORR activity. This work shows SHINERS is a promising technique for the real‐time observation of catalytic processes. 相似文献
119.
Nadya E. Stankova Ivan G. Dimitrov Petar A. Atanasov 《Applied Surface Science》2009,255(10):5275-5279
The evolution of the crystal, the microstructural and the optical properties of pulsed-laser deposited TiO2 films, investigated by X-ray diffraction, atomic force microscopy, scanning electron microscopy, optical transmittance and m-line spectroscopy measurements are reported. The samples were grown on (0 0 1) SiO2 substrates at temperatures from 250 to 600 °C and oxygen pressures from 1 to 15 Pa. Crystalline films consisting of single anatase or anatase and rutile phases, were obtained at temperatures higher than 400 °C. A tendency toward columnar-like growth morphology was observed in the samples. Strong dependence of the optical properties on the surface roughness and the microstructure was determined. All films revealed single-mode waveguiding and optically anisotropic properties. 相似文献
120.
Petar R. Dvornic 《Journal of polymer science. Part A, Polymer chemistry》1986,24(6):1133-1160
A series of wholly aromatic polyamide-hydrazides was investigated in order to acquire clear understanding of the influence exerted by controlled structural variations in these polymers upon some of important properties, such as chain flexibility, membrane permselectivity, and thermal as well as thermo-oxidative stability. For that reason, the content of para and meta phenylene units was varied within this series so that the changes in the latter were 12.5 mol % from polymer to polymer, starting from an overall content of 0–50 mol %. The polymers were prepared by a low-temperature solution polycondensation reactin of p-aminobenzhydrazide (ABH) and terephthaloyl chloride (TCI), isophthaloyl chloride (ICI), and their appropriate combinations in N,N-dimethylacetamide (DMA) as solvent and all of these preparations were monitored viscometrically in order to prepare the products with as similar as possible average molecular weights. Polymer structures were characterized by elemental analysis, infrared spectrometry, and 13C NMR spectroscopy, while their molecular weights were determined by light scattering and dilute-solution viscometry. Polymer properties were evaluated by solution viscometry, reverse osmosis tests, and thermal gravimetric analysis. The results obtained during the preparation of these materials, their subsequent structural characterization, and their property evaluations are discussed. They clearly indicate that substitution of m-phenylene units for p-phenylene ones within this polymer series led to an increase in polymer chain flexibility (from what is usually referred to as semiflexible or semirigid to typically flexible macromolecules), disrupted selectivity of the asymmetric thin membranes under reverse osmosis conditions and decreased stability at elevated temperatures in inert as well as in oxidative atmospheres. 相似文献