Chaotic behavior of channeling particles

Channeling describes the collimated motion of energetic charged particles along the lattice plane or axis in a crystal. The energetic particles are steered through the channels formed by strings of atomic constituents in the lattice. In the case of planar channeling, the motion of a charged particle between the atomic planes can be periodic or quasiperiodic, such as a simple oscillatory motion in the transverse direction. In practice, however, the periodic motion of the channeling particles can be accompanied by an irregular, chaotic behavior. In this paper, the Moliere potential, which is considered as a good analytical approximation for the interaction of channeling particles with the rows of atoms in the lattice, is used to simulate the channeling behavior of positively charged particles in a tungsten (100) crystal plane. By appropriate selection of channeling parameters, such as the projectile energy E(0) and incident angle psi(0), the transition of channeling particles from regular to chaotic motion is demonstrated. It is argued that the fine structures that appear in the angular scan channeling experiments are due to the particles' chaotic motion.     

Theoretical Study on the Mass Transfer of Metal Ions in Ion Exchange Process

The kinetics of ion exchange between Ca2 , Mg2 , Co(Ⅱ), Cu(Ⅱ),Ni(Ⅱ), Fe(Ⅲ), y3 or Sm3 , respectively, in 0.50 mol/L HC1 and H on macrorecticular sulfonic ion exchange resin and the kinetics of the same reactions (M -H exchange) when Mn(Ⅱ) coexisted in resin phase as accelerating ion were studied. The accelerating effect manifested and its rule are consistent with the accelerating effect theory based on the concept concerned with adsorption electrical double layer which has been suggested in a previous paper published.     

偏最小二乘-速差动力学分光光度法同时测定杀虫剂残杀威和异丙威两组分

采用速差动力学分光光度法对氨基甲酸脂类杀虫剂残杀威和异丙威进行同时测定，这两种化 的能在碱性条件下水解生成酚盐，进而与对氨基苯酚及高碘酸钾的反应产物醌亚胺发生偶联反应，生成蓝色化合物。反应的速率适中，可用于动力学分析。实验采集了多个时间点下538－700nm间的动力学－吸光度数据，构成量测矩阵，并采用偏最小二乘（PLS）法对量测数据进行解析。本文还对合成样品和环境水样中的残杀威和异丙威含量进行测定，获较好的结果。     

Effect of La_2O_3/γAl_2O_3 Catalyst on the Activation of CH_4 and CO_2 to C_02 Hydrocarbons under Non-equilibrium Plasma

The oxidative coupling of methane (OCM) to C2 hydrocarbons using carbon dioxide as oxidant is an attractive process from environmental point of view. Only a few research papers reported for it1-3. In general, the yield of C2 hydrocarbons was about 6%. This indicated that the method of catalytic activation was unfavorable to the reaction. It is necessary for us to find a new method in order to activate reaction and improve C2 hydrocarbon yield. Non-equilibrium plasma is a cold plasma in…     

Involvement of human small fragment nuclease in the resistance of human cells to UV-C-induced cell death

Human small fragment nuclease (Sfn) is one of the cellular proteins that were reported to degrade small, single-stranded DNA and RNA. However, the biological role of Sfn in cellular response to various stressors such as UV-C (mainly 254 nm wavelength ultraviolet ray) remains unclear. We have examined whether modulation of human SFN gene expression affects cell survival capacity against UV-C-induced cell death, analyzing colony survival ability in UV-C-sensitive human RSa cells treated with short double-stranded RNA (siRNA) specific for SFN messenger RNA (mRNA). The expression levels of SFN mRNA in the siRNA-treated RSa cells decreased to about 15% compared with those in the control siRNA-treated cells. The siRNA-treated RSa cells showed lower colony survival and higher activity of caspase-3 after UV-C irradiation than the control siRNA-treated RSa cells. Furthermore, the removal capacity of cyclobutane pyrimidine dimers (CPD) in the siRNA-treated RSa cells decreased compared with the control siRNA-treated RSa cells. There was no difference in the colony survival and CPD removal capacity after UV-C irradiation between the control siRNA-treated RSa cells and mock-treated RSa cells. These results suggest that SFN expression is involved in resistance of RSa cells to UV-C-induced cell death through the roles it plays in the DNA repair process.     

A New Dimeric Phthalide from Angelica sinensis

Angelica sinensis (Oliv.) Diels (Umbelliferae), known as Danggui in Chinese, one of the most important traditional Chinese medicines, is used for tonifying blood and treating female irregular menstruation and amenorrhoea. It is also used for treatment of …     

Design, Synthesis and Investigation of Bone Affinity of the Conjugates of 5-Fluorouracil and Hydroxybisphosphonate

Bone tumor, as a common disease, is treated by surgical resection, radiotherapy and chemotherapy. Chemotherapy is one of the most important treatment, however, a major problem of chemotherapy is lack of selectivity of cytotoxic drugs. Although many attempts have been made to increase the selectivity of therapeutic drugs for the bone diseases, such as osteoporosis, paget’s, hypercalcemia and bone metastases by conjugating them with targeting carriers1-4, there are still no bone-targeting agent…     

Mass transfer in shell-core inorganic TIP1 ion exchanger

The ion exchange processes of (OAc^–) and (OAc^–) proceeding in shell-core inorganic ion exchanger Ti (HPO₄)₂·1/2H₂O has been studied and the diffusion equation whose boundary conditions are satisfied by a shell-core model was solved. Based on the equation solved and experimental data, the diffusion coefficients corresponding to the exchange process (OAc^–) and Li⁺–H⁺ (OAc^–) at 17°C are found to be 7.7×10^–9 and 6.2×10^–8 cm² s^–1 and the activation energies 3.4×10⁴ and 5.0×10³ J mol^–1, respectively. Compared to the gel type of styrene-divinylbenzene strong acid exchanger with 20% cross linking, it can be concluded that the rate of or exchange is 3.5 times faster than that in the organic exchanger.TIP was obtained from the Salt Lake Institute of the Academy of Science of China.