Quantum Anti-Zeno Effect in Nuclear Decay

The acceleration of decay induced by frequency measurements,namely the quantum anti-Zeno effect(AZE),was first predicted by Kofman and Kurizki [Nature 405(2000) 546].The effect of the frequency measurements on nuclear β decay rate is analyzed based on the time-dependent perturbation theory.We present a detailed calculation of the decay rates of ~3H,~(60)Co(β~-type),~(22)Na,~(106)Ag(β~+ type) and ~(18)F,~(57)Co and ~(111)Sn(EC type)under frequency measurements.It is found that the effects of frequency measurements on the decay rates of β~+and β~-cases are different from the case of EC,and the smaller the β decay energy is,the more favorable it is to observe the AZE in experiment.Based on our analysis,it is suggested that possible experimental candidates should have a small decay energy and a reasonable half life(such as ~3H) for observing the AZE in β decay.     

Thermal stress reduction of GaAs epitaxial growth on V-groove patterned Si substrates

We investigate the thermal stresses for GaAs layers grown on V-groove patterned Si substrates by the finite-element method. The results show that the thermal stress distribution near the interface in a patterned substrate is nonuniform,which is far different from that in a planar substrate. Comparing with the planar substrate, the thermal stress is significantly reduced for the Ga As layer on the patterned substrate. The effects of the width of the V-groove, the thickness, and the width of the SiO₂ mask on the thermal stress are studied. It is found that the SiO₂ mask and V-groove play a crucial role in the stress of the Ga As layer on Si substrate. The results indicate that when the width of V-groove is 50 nm, the width and the thickness of the SiO₂ mask are both 100 nm, the Ga As layer is subjected to the minimum stress. Furthermore,Comparing with the planar substrate, the average stress of the Ga As epitaxial layer in the growth window region of the patterned substrate is reduced by 90%. These findings are useful in the optimal designing of growing high-quality Ga As films on patterned Si substrates.     

Reduction in Allergenicity and Induction of Oral Tolerance of Glycated Tropomyosin from Crab

Tropomyosin (TM) is an important crustacean (Scylla paramamosain) allergen. This study aimed to assess Maillard-reacted TM (TM-G) induction of allergenic responses with cell and mouse models. We analyzed the difference of sensitization and the ability to induce immune tolerance between TM and TM-G by in vitro and in vivo models, then we compared the relationship between glycation sites of TM-G and epitopes of TM. In the in vitro assay, we discovered that the sensitization of TM-G was lower than TM, and the ability to stimulate mast cell degranulation decreased from 55.07 ± 4.23% to 27.86 ± 3.21%. In the serum of sensitized Balb/c mice, the level of specific IgE produced by TM-G sensitized mice was significantly lower than TM, and the levels of interleukins 4 and interleukins 13 produced by Th2 cells in spleen lymphocytes decreased by 82.35 ± 5.88% and 83.64 ± 9.09%, respectively. In the oral tolerance model, the ratio of Th2/Th1 decreased from 4.05 ± 0.38 to 1.69 ± 0.19. Maillard reaction masked the B cell epitopes of TM and retained some T cell epitopes. Potentially, Maillard reaction products (MRPs) can be used as tolerance inducers for allergen-specific immunotherapy.     

液晶光阀的偏光显示特性分析

讨论了液晶光阀的偏光扭曲向列性效应, 分析了液晶光阀中液晶分子在交流电场作用下重新取向后的扭曲, 测量了TB3639型液晶光阀在特定的频率连续改变外加交流电压条件下,液晶分子重新取向后的扭曲角度以及液晶光阀的电光特性。测量结果表明,在外加电压连续改变时,入射线偏振光的透射率呈现连续非线性变化,这种非线性变化可以由液晶分子的扭曲量来改变。同时液晶分子180°的扭曲使得液晶光阀具有较陡的电光特性曲线,这对于多通道矩阵寻址方式的液晶光阀而言在矩阵显示中可有更多的通道寻址线和更高的对比度。     

Probing quark-distribution amplitudes through generalized parton distributions at large momentum transfer

In the large momentum transfer limit, generalized parton distributions can be calculated through a QCD factorization theorem which involves perturbatively calculable hard kernels and light-cone parton distribution amplitudes of hadrons. We illustrate this through the H(q)(x,xi,t) distribution for the pion and the proton, presenting the hard kernels at leading order. As a result, experimental data on the generalized parton distributions in this regime can be used to determine the functional form of the parton distribution amplitudes which has thus far been quite challenging to obtain. Our result can also be used as a constraint in phenomenological generalized parton distribution parametrizations.     

A Simple Bi-directional Mode Expansion Propagation Algorithm Based on Modes of a Parallel-plate Waveguide

The bi-directional mode expansion propagation algorithm (BEP) is known to be an accurate and efficient method for modelling field distribution in high-index contrast waveguide structures with strong back-reflections like Bragg gratings and photonic crystals. The main difficulty of this method is that for lossy structures, the propagation constants of modes are to be searched in the complex plane. To speed-up this procedure, a two-step algorithm for eigenmode calculation based on the expansion into the modes of an empty metallic waveguide has recently been proposed. Proper truncation rules possessing good convergence of the expansion method for both TE and TM modes have also been recently published. In this contribution, both these approaches are combined in the development of an extremely simple version of the two-dimensional BEP method that makes use of the field expansion into the eigenmodes of a parallel-plate waveguide. The method is strictly reciprocal and appeared to be computationally reliable also for strongly lossy structures. High numerical stability is ensured using the scattering matrix formalism, and an efficient method of calculating Bloch modes for symmetric as well as asymmetric periodic waveguide structures is adopted. A wide range of applicability of the method is demonstrated by a few examples.     

Effect of ultrasound on adsorption of Geniposide on polymeric resin

The effects of pulse ultrasound with different pulse parameter on the adsorption isotherm and kinetics of Geniposide on Resin 1300 were studied. And the mass transfer model describing the adsorption process was constructed. Amount of Geniposide adsorbed on Resin 1300 in the presence of ultrasound is lower than that in the absence of ultrasound. At our experimental conditions, the adsorption equilibrium constant decreases with increasing ultrasonic intensity and pulse duty ratio, and with decreasing pulse period. In addition, pulse ultrasound can enhance both liquid film diffusion and intraparticle diffusion, and the intensification of liquid film diffusion with pulse ultrasound is stronger than that of intraparticle diffusion. The intraparticle diffusion coefficient D(e)/R2 increases with increasing ultrasonic intensity and pulse duty ratio, and with decreasing pulse period.     

Evaluation of the dosimetric characteristics of a radiophotoluminescent glass dosimeter for high-energy photon and electron beams in the field of radiotherapy

We aimed to evaluate the suitability of a glass dosimeter (GD) for high-energy photon and electron beams in experimental and clinical use, especially for radiation therapy. We examined the expanded dosimetric characteristics of GDs including dose linearity up to 500 Gy, uniformity among GD lots and for individual GDs, the angular dependence, and energy dependence of 4 therapeutic x-ray qualities. In addition, we measured the dosimetric features (dose linearity, uniformity, angular dependence, and energy dependence) of the GD for electron beams of 10 different electron energy qualities. All measurements with the exception of dose linearity for photon beam were performed in a water phantom. For high-energy photon beams, dose linearity has a linear relationship for a dose ranging from 1 to 500 Gy with the coefficient of determination; R² of 0.998. The uniformity of each GD of dose measurements was within ±0.5% for four GD lots and within ±1.2% for 80 GDs. In terms of the effects of photon beam angle, lower absorbed doses of within 1.0% were observed between 60° and 105° than at 90°. The GD energy dependence of 4 photon beam energy qualities was within ±2.0%. On the other hand, the result of the dose linearity for high-energy electron beams showed well fitted regression line with the coefficient of determination; R² of 0.999 between 6 and 20 MeV. The uniformity of GDs exposed to the nominal electron energies 6, 9, 12, 16, and 20 MeV was ±1.2%. In terms of the angular dependence to electron beams, absorbed doses were within 2.0% between 60° and 105° than at 90°. In evaluation of the energy dependence of the GD at nominal electron energies between 5 and 20 MeV, we obtained responses between 1.1% and 3.5% lower than that for a cobalt-60 beam. Our results show that GDs can be used as a detector for determining doses when a high-energy photon beam is used, and that it also has considerable potential for dose measurement of high-energy electron beam.     

High efficiency top-emitting white organic light-emitting devices with a (metal/organic)2 cathode

White top-emitting organic light-emitting devices (TEOLEDs) were fabricated on a glass substrate with metal/organic multilayer of (Ag/Alq₃)₂ (Alq₃ is tris-(8-hydroxyquinoline) aluminum) as cathode. White TEOLEDs with high efficiency were obtained due to the microcavity effects. And the (Ag/Alq₃)₂ cathode, which adjusted the optical characteristics of the devices, played an important role. In addition, Alq₃–Ag–Alq₃ multilayer could work as a buffer layer, which would simplify the process of encapsulation for devices. We also calculated the electroluminescence spectrum of devices encapsulated with Al₂O₃ (150 nm) and Al₂O₃(75 nm)/ZrO₂(75 nm). And the results indicated that the CIE coordinates is almost the same between with and without encapsulating.