Knockout reaction mechanism studied by 6He projectile

Knockout reaction experiment was carried out by using the ⁶He beams at 61.2 MeV/u impinging on a CH₂ target. The α core fragments at forward angles were detected in coincidence with the recoiled protons at larger angles. From this exclusive measurement the valence nucleon knockout mechanism and the core knockout mechanism can be distinguished by the relation between the polar angles of the core fragments and the recoiled protons, respectively. It is demonstrated that the core knockout mechanism may result in some strong contamination to the real invariant mass spectrum.

     

Photoisomerization of the Graft Copolymer of Starch and Azo-dye

Optical data storage materials are mainly based on organic molecules. To be suited for as an optical data storage material, molecules have to be photochromatic, they must be capable of being reversibly switched be. tween two spectroscopically distinct forms by use of light[1].Photoisome rization (trans ～cis) of azoaromatic compounds has been investigated extensively using UV-Vis spectroscopy. In 1972[2], the isomerization of various azobenzenes bound on the side chain or within the main chain of poly (methyl methacrylate), poly(ethyl methacrylate),polystyrene, a polyamide, and polyester had. been demonstrated. There are three processes: a trans-cis photochemical isomerization, a cis-trans photochemical isomerization, and a cis-trans thermal isomerization, which occurs due to the higher stability of the trans configuration, since that pioneering study, two main directions of research developed and are very active in the eurrent literature.     

Simultaneous determination of components in preparation Naodesheng injection by high performance liquid chromatograph-atmospheric pressure chemical ionization mass spectrometry (HPLC-MS/APCI)

A high-performance liquid chromatograph with mass spectrum detection (HPLC-MS/APCI) method has been established for simultaneous determination of ten major bioactive components of Naodesheng injection including safflor yellow A, puerarin, daidzein, ginsenosides (Rg1, Rg2, Rb1, Rd, Re, Rh1), and notoginsenoside R1. The separations were carried out with a Luna C18 column (5 microm, 150x4.6 mm, Phenomenex, U.S.A.) with a stepwise gradient elution of the mobile phase consisting of water (0.1% of formic acid, v/v)-methanol (0 min, 70:30; 8 min, 30:70; 20 min, 10:90) at a flow-rate of 0.8 ml/min. The proposed method was applied to analyze five various Naodesheng injections and produced data with acceptable linearity, repeatability, precision and accuracy having lower limits of quantitation (LLOQs) of 0.02-0.2 microg. The calibration curves were linear in respective range for all compounds, all of them with coefficients of determination above 0.9900. The intraday precessions were less than 5.0%. The proposed method is accurate, sensitive and simple, a useful alternative for routine analysis in the quality control of Traditional Chinese Medicine.     

GaN-based LEDs for light communication

Rapid improvement in the efficiency of GaN-based LEDs not only speed up its applications for general illumination, but offer the possibilities for data transmission. This review is to provide an overview of current progresses of GaN-based LEDs for light communications. The modulation bandwidth of GaN-based LEDs has been first improved by optimizing the LED epilayer structures and the modulation bandwidth of 73 MHz was achieved at the driving current density of 40 A/cm² by changing the multi-quantum well structures. After that, in order to increase the current density tolerance, different parallel flip-chip micro-LED arrays were fabricated. With a high injected current density of ～7900 A/cm², a maximum modulation bandwidth of ～227 MHz was obtained with optical power greater than 30 mW. Besides the increase of carrier concentrations, the radiative recombination coefficient B was also enhanced by modifying the photon surrounding environment based on some novel nanostructures such as resonant cavity, surface plasmon, and photonic crystals. The optical 3 dB modulation bandwidth of GaN-based nanostructure LEDs with Ag nanoparticles was enhanced by 2 times compared with GaN-based nanostructure LEDs without Ag nanoparticles. Our results demonstrate that using the QW-SP coupling can effectively help to enhance the carrier spontaneous emission rate and also increase the modulation bandwidth for LEDs, especially for LEDs with high intrinsic IQE. In addition, we discuss the progress of the faster color conversion stimulated by GaN-based LEDs.     

The design and construction of a pulsed beam generation system based on high intensity cyclotron

In order to perform the studies on a pulsed beam generation system based on a high intensity cyclotron, a test beam line with a pulsed beam generation for a 10 MeV compact cyclotron (CYCIAE-10) has been designed and constructed at China Institute of Atomic Energy (CIAE). A 70 MHz continuous H-beam can be pulsed to the pulse length of less than 10 ns with a repetition rate of 4.4 MHz. The sine waveform with a frequency of 2.2 MHz is adopted for the chopper and a mesh structure with single drift and dual gaps is used for the 70 MHz buncher. A helical resonator is designed and constructed based on simulations and experiments on the RF matching for the chopper. A helical inductance loop that is exceptionally large of its kind and equipped with water cooling for the resonator has been successfully wound and a 500 W solid RF amplifier has been manufactured. A special measuring device has been designed, which can be used to measure both the DC beam and the pulsed beam. The required pulsed beam was obtained after pulsed beam tuning.     

Experimental research into the two-proton emissions from ~(17,18) Ne,~(28) P and ~(28,29)S

Two-proton emissions from the excited states of 17,18Ne, 28P and 28,29S were investigated experimentally by the radioactive beams bombarding on the 197Au target via the Coulomb excitation. The complete-kinematics measurements were actualized by the stacks of silicon-strip detectors and CsI+PIN array detectors. The invariant mass of final systems as well as the relative momentum, opening angle, and relative energy of the two emitted protons was reconstructed under the framework of relativ istic kinematics. V...     

Further results on existence-uniqueness for stochastic functional differential equations

The aim of this paper is to develop some basic theories of stochastic functional differential equations (SFDEs) under the local Lipschitz condition in continuous functions space ?. Firstly, we establish a global existence-uniqueness lemma for the SFDEs under the global Lipschitz condition in ? without the linear growth condition. Then, under the local Lipschitz condition in ?, we show that the non-continuable solution of SFDEs still exists if the drift coefficient and diffusion coefficient are square-integrable with respect to t when the state variable equals zero. And the solution of the considered equation must either explode at the end of the maximum existing interval or exist globally. Furthermore, some more general sufficient conditions for the global existence-uniqueness are obtained. Our conditions obtained in this paper are much weaker than some existing results. For example, we need neither the linear growth condition nor the continuous condition on the time t. Two examples are provided to show the effectiveness of the theoretical results.     

Fluorescence turn-on chemosensor for Hg~(2+) based on a rhodamine derivative and its application in bioimaging

A fluorescence turn-on chemosensor based on rhodamine B derivative (FD10) has been developed as a highly sensitive chemosensor for Hg2+. A prominent fluorescence enhancement was measured in the presence of Hg2+, which was in agreement with the changes in the absorption spectrum. Furthermore, by means of laser scanning fluorescence microscopy experiments, it was demonstrated that FD10 was cell-permeable and could be used as a fluorescent probe for monitoring Hg2+ in living cells.     

Clay-protein ultrathin films: Design and bio-catalytic performance study

In recent years,immense interest has been paid to the biomolecular architecture with the aim of protein assembly in two dimensions on solid substrates,and the constructions of clay-protein ultrathin films(CPUFs) are particularly concerned.This paper gives an overview of the recent research concerning the protein molecules(lysozyme,papain,protamine,bovine serum albumin) immobilized on clay mineral(Na-saponite) platelets and assembled in monolayered or multilayered hybrid ultrafilms or nanofilms.Two techniques including alternate layer-by-layer(LbL) assembly and the Langmuir-Blodgett(LB) are described in detail.A variety of means,including UV-vis absorption,attenuated total reflectance Fourier transform infrared(ATR-FTIR) spectroscopy,XRD,AFM and surface chemistry techniques,have been described for characterization of the films in terms of quantification of protein and clay.The result reveals that electrostatic interaction is a prominent but not the only driving force in CPUF construction.In the case of LB technique,we managed to manipulate the elementary clay mineral platelets(1.3 nm in thickness) and assemble proteins into CPUFs with the aid of surfactants,and the formation of CPUFs was monitored via surface pressure vs.time(π-t) kinetics curves and surface pressure vs.area(π-A) isotherms.The factors that influence protein adsorption on the clay layer,such as surfactants,the concentration of clay,equilibrium time,categories of protein,and injection methods,were investigated.The parameters such as protein amount(nS),packing density(■),and average surface area per molecule(Ω) of deposited CPUFs were measured via method of surface chemistry and spectroscopy.By comparing the results of surface chemistry with those of adsorption experiments,we demonstrate that the surface chemistry method is a useful tool in investigating CPUFs.We also found that the water soluble protein molecules could form protein-clay hybrid monolayer over the dilute clay dispersions without addition of surfactants,and CPUFs containing elementary clay sheets and protein with great homogeneity were easily prepared by controlling certain surface pressure.To investigate the bio-catalytic performance of the immobilized lysozyme in CPUFs,we deposited CPUFs onto a cover glass,and installed the cover glass in a flow cell-grown reactor for Comamonas testosteroni(WDL7-GFP) incubation.The results show that the proliferation of WDL7-GFP is greatly suppressed by lysozyme,which demonstrates that lysozyme still retains its bioactivity after it is immobilized in the CPUFs.     

Two-photon absorption in V-type chromophores with electron-rich heterocyclevinylene bridges

A series of V-type chromophores with electron-rich heterocyclevinylene bridges have been synthesized via Wittig-Horner-Emmons and Vilsmeier reactions.All the target chromophores showed strong one-photon and two-photon excited emission,and their electron properties could be tuned by using different heterocycles such as furan,thiophene and pyrrole moieties in I-III.The maximum two-photon absorption (TPA) cross sections occurred at 760 nm and were measured to be in the range of 400-800 GM.