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111.
For realization of future high performance integrated networks, broadband distribution and access networks and to meet the increasing demand of multimedia services with a guaranteed quality of service, RoF technology comes out as the most promising technology that combines the capacity of optical networks with the flexibility and mobility of wireless networks. Reduction in complexity at the antenna site, reduction in installation cost of access networks, possibility of dynamically allocation of radio carriers to different antenna sites, transparency and scalability are the few advantages of radio-over-fiber (RoF) technology. In this paper, we review the different challenges that limit the probable capabilities of RoF communication networks and different mitigation techniques to combat with these challenges to realize high-performance RoF links. 相似文献
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113.
Shepherd NE Hoang HN Desai VS Letouze E Young PR Fairlie DP 《Journal of the American Chemical Society》2006,128(40):13284-13289
A 13-residue peptide sequence from a respiratory syncitial virus fusion protein was constrained in an alpha-helical conformation by fusing two back-to-back cyclic alpha-turn mimetics. The resulting peptide, Ac-(3-->7; 8-->12)-bicyclo-FP[KDEFD][KSIRD]V-NH(2), was highly alpha-helical in water by CD and NMR spectroscopy, correctly positioning crucial binding residues (F488, I491, V493) on one face of the helix and side chain-side chain linkers on a noninteracting face of the helix. This compound displayed potent activity in both a recombinant fusion assay and an RSV antiviral assay (IC(50) = 36 nM) and demonstrates for the first time that back-to-back modular alpha-helix mimetics can produce functional antagonists of important protein-protein interactions. 相似文献
114.
Mayani VJ Abdi SH Kureshy RI Khan NH Agrawal S Jasra RV 《Journal of chromatography. A》2006,1135(2):186-193
A new chiral stationary phase (CSP) was synthesized based on (S)-1-anilino-3-propyl-2-propanol covalently bonded to the mesoporous semi-crystalline material M41S. Direct semipreparative enantioseparation of mandelic acid could be achieved using medium pressure chromatography. Partly separated could also be the enantiomers of 2,2'-dihydroxy-1,1'-binaphthalene, cyanochromene oxide, diethyl tartrate and 2-phenyl propionic acid. The characterization of CSP was accomplished by microanalysis, cross polarized magic angle spinning (CP-MAS) 13C NMR, powder X-ray diffraction (XRD), FTIR, thermo-gravimetric analysis (TGA), N2 adsorption-desorption isotherm, scanning electron microscopy (SEM) and solid reflectance UV-vis spectroscopy. Furthermore the stability of CSP was satisfactory as it could withstand three washing and reuse experiments of enantioseparation of mandelic acid without loss in its performance. 相似文献
115.
Joe D. Oxman Dwight W. Jacobs Matthew C. Trom Vishal Sipani Beth Ficek Alec B. Scranton 《Journal of polymer science. Part A, Polymer chemistry》2005,43(9):1747-1756
Free‐radical/cationic hybrid photopolymerizations of acrylates and epoxides were initiated using a three‐component initiator system comprised of camphorquinone as the photosensitizer, an amine as the electron donor, and a diaryliodonium salt. Thermodynamic considerations revealed that the oxidation potential of the electron donor must be less than 1.34 V relative to SCE for electron transfer with the photoexcited camphorquinone to take place. This electron transfer leads to the production of the active centers for the hybrid polymerization (two radicals and a cation). Further investigation revealed that only a subset of electron donors that meet the oxidation potential requirement resulted in polymerization of the epoxide monomer; therefore, a second requirement for the electron donor (pKb higher than 8) was established. Experiments performed using a combination of electron donors revealed that the onset of the hybrid system's cationic polymerization can be advanced or delayed by controlling the concentration and composition of the electron donor(s). These studies demonstrate that a single three‐component initiator system can be used to initiate and chemically control the sequential curing properties of a free‐radical/cationic hybrid photopolymerization and is a viable alternative to separate photoinitiators for each type of polymerization. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1747–1756, 2005 相似文献
116.
A transition metal–free process, promoted by sodium borohydride, has been developed for convenient and selective hydration of nitriles to corresponding amides. The present process converts the aromatic, aliphatic, and heteroaromatic nitriles with wide functional group tolerance. The regioselective hydration of one nitrile moiety in the presence of an other nitrile group makes high impact in the present protocol. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.] 相似文献
117.
Versatile Synthetic Strategy for Coating Upconverting Nanoparticles with Polymer Shells through Localized Photopolymerization by Using the Particles as Internal Light Sources
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Selim Beyazit Dr. Serena Ambrosini Dr. Nataliya Marchyk Emilia Palo Vishal Kale Prof. Tero Soukka Dr. Bernadette Tse Sum Bui Prof. Karsten Haupt 《Angewandte Chemie (International ed. in English)》2014,53(34):8919-8923
We present a straightforward and generic strategy for coating upconverting nanoparticles (UCPs) with polymer shells for their protection, functionalization, conjugation, and for biocompatibility. UCPs are attracting much attention for their potential use as fluorescent labels in biological applications. However, they are hydrophobic and non‐compatible with aqueous media; thus prior surface modification is essential. Our method uses the internal UV or visible light emitted from UCPs upon photoexcitation with near‐infrared radiation, to locally photopolymerize a thin polymer shell around the UCPs. In this way, a large variety of monomers with different chemical functionalities can be incorporated. If required, a second layer can be added on top of the first. Our method can provide a large spectrum of surface functional groups rapidly and in one pot, hence offering a platform for the preparation of libraries of functional polymer‐encapsulated UCPs for applications in bioassays, biosensing, optical imaging, and theranostics. 相似文献
118.
Michael Marquardt Dr. Beatrice Cula Vishal Budhija Dr. André Dallmann Dr. Matthias Schwalbe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(12):3991-3996
The synthesis and characterization of a hetero-dinuclear compound is presented, in which a copper(I) trishistidine type coordination unit is positioned directly above a zinc porphyrin unit. The close distance between the two coordination fragments is secured by a rigid xanthene backbone, and a unique (intramolecular) copper porphyrin-π-bond was determined for the first time in the molecular structure. This structural motif was further analyzed by temperature-dependent NMR studies: In solution at room temperature the coordinative bond fluctuates, while it can be frozen at low temperatures. Preliminary reactivity studies revealed a reduced reactivity of the copper(I) moiety towards dioxygen. The results adumbrate why nature is avoiding metal porphyrin-π-bonds by fixing reactive metal centers in a predetermined distance to each other within multimetallic enzymatic reaction centers. 相似文献
119.
Kore Gurupad D. Zanje Sunil B. Kokare Arjun N. Suryavanshi Vishal J. Anuse Mansing A. Kolekar Sanjay S. 《Journal of Radioanalytical and Nuclear Chemistry》2021,329(2):975-982
Journal of Radioanalytical and Nuclear Chemistry - The analytical technique has been developed for the extraction and determination of uranium(VI). This process is based on the ion-pair complex... 相似文献
120.
The samples of CR-39(DOP) and SR-90 polymer track detectors have been exposed to -particles from 241Am source in an exposure unit. The temperature of the detectors during irradiation has been varied from −30°C to 70°C. These exposed samples have been etched in 6.25 N NaOH solution at 60°C for various etching times. The variation of sensitivity of these detectors as a function of registration temperature has been studied. It has been observed that at the fixed registration temperature, the sensitivity of SR-90 is more than CR-39(DOP) polymer track detector. However, the enhancement in sensitivity with the decrease in registration temperature is more pronounced in case of CR-39(DOP) than SR-90. 相似文献