Potential Mechanisms of Photodynamic Inactivation of Virus by Methylene BlueI. RNA–Protein Crosslinks and Other Oxidative Lesions in Qβ Bacteriophage

A spectrum of oxidative lesions was observed in a bacteriophage-based model system that is very sensitive to the photodynamic activity of selected dyes. When suspensions of the intact bacteriophage Qβ were exposed to methylene blue plus light (MB+L), inactivating events, or "hits" occurred that were oxygen-dependent and that were associated with the formation of several specific lesions: (1) carbonyl moieties on proteins, (2) 8-oxo-7,8-dihydroguanine (8-oxoGua), and (3) single-strand breaks (ssb) in the RNA genome and (4) RNA-protein crosslinks. Formation of carbonyl groups associated with protein in the Qβ phage preparation correlated positively with photoinactivation of the phage with increasing doses of either of the sensitizers MB or rose bengal. Strand breaks in the Qβ genomic RNA were observable at high MB concentrations but appeared not to be significant at the lower concentrations of MB, as full-length Qβ RNA was observable well beyond the 99% inactivation point in MB dosage. It was shown that the number of 8-oxoGua lesions were unlikely to be sufficient to account for the number of lethal events. Following exposure to MB+L, crosslink formation between Qβ RNA and protein was observed by virtue of the location of RNA at the interface of phenol-aqueous extractions of phage suspensions. A significant increase over background of RNA-protein complexes (including full-length Qβ RNA) was observed at the lowest concentration of MB tested (0.5 μ M ), which corresponded roughly to an average of 2 lethal hits per phage or approximately 13% survival compared to the zero MB control (100% survival). Due to its close correlation with Qβ inactivation and its expected lethality, RNA-protein crosslink formation may be important as an inactivating lesion in bacteriophage Qβ following MB+L exposure.     

Anticancer Drugs ( Ⅳ )——New Derivatives of Podophyllotoxin

Four new derivatives of podophyllotoxin, N'-podophyllic acid-N-[3-(2, 2, 5, 5-te-tramethyl-pyrrolinenyloxy)] semicarbazide(GP-11, 6), podophyllic acid [3-(2,2,5,5-te-tramethyl-pyrrolinenyloxy)]hydrazone (GP-12, 7), podophyllic acid-[4-(2, 2, 6, 6-tetramethyl-1-hydroxy piperidine)]hydrazone(GP-1-OH, 8) and podophyllic acid[4-(2,2, 6, 6-tetramethyl piperidine)]hydrazone(GP-1-H, 9) were synthesized. The inhibition effect of the four new compounds on L-1210 cells were determined. The antitumor activity and toxicity of GP-1(2), GP-1-OH(8), GP-1-H(9) and VP-16-213(1) were discussed.     

L-脯氨酸催化下甲基酮和1-芳基-2,2,2-三氟乙酮的不对称Aldol反应

Direct asymmetric aldol addition of methyl ketones to 2,2,2-trifluoro-1-phenylethanone and its ring-substituted derivatives was achieved using L-proline as a chiral promoter. Various optically active β-trifluoromethyl-β-hydroxy ketones were obtained in almost quantitative yields with moderate enantioselectivities up to 64 % ee.     

Z‐bpy,a New C2‐Symmetric Bipyridine Ligand and Its Application in Enantioselective Copper(I)‐Catalyzed Cyclopropanation of Olefins

A rigid C₂‐symmetric chiral bipyridine ligand Z‐bpy with a triptycene‐like backbone was designed and synthesized from simple chemicals in a scalable route. Using this new ligand, copper(I) catalyzed cyclopropanation of styrenes with commercial ethyl diazoacetate produced various corresponding cyclopropanes in high yields, diastereoselectivity and enantioselectivity up to 97% ee.     

Analytical study of Joule heating effects on electrokinetic transportation in capillary electrophoresis

Electric fields are often used to transport fluids (by electroosmosis) and separate charged samples (by electrophoresis) in microfluidic devices. However, there exists inevitable Joule heating when electric currents are passing through electrolyte solutions. Joule heating not only increases the fluid temperature, but also produces temperature gradients in cross-stream and axial directions. These temperature effects make fluid properties non-uniform, and hence alter the applied electric potential field and the flow field. The mass species transport is also influenced. In this paper we develop an analytical model to study Joule heating effects on the transport of heat, electricity, momentum and mass species in capillary-based electrophoresis. Close-form formulae are derived for the temperature, applied electrical potential, velocity, and pressure fields at steady state, and the transient concentration field as well. Also available are the compact formulae for the electric current and the volume flow rate through the capillary. It is shown that, due to the thermal end effect, sharp temperature drops appear close to capillary ends, where sharp rises of electric field are required to meet the current continuity. In order to satisfy the mass continuity, pressure gradients have to be induced along the capillary. The resultant curved fluid velocity profile and the increase of molecular diffusion both contribute to the dispersion of samples. However, Joule heating effects enhance the sample transport velocity, reducing the analysis time in capillary electrophoretic separations.     

铁掺杂PMP泡沫制备工艺研究

 以聚-4-甲基-1-戊烯为泡沫骨架，二茂铁为掺杂材料，通过热诱导倒相技术制备出铁掺杂聚合物泡沫。掺杂泡沫的实际密度均高于理论密度，且沿轴向从上至下逐渐增大。在理论密度不变的情况下，掺杂泡沫实际密度随掺杂元素原子百分含量的升高而呈降低趋势。与PMP泡沫相比，掺杂泡沫的孔洞直径分布变宽且网络骨架尺寸有变大的趋势。     

Some Topological Properties of Solution Sets in a Second Order Differential Inclusion with m-point Boundary Conditions

We consider a class of m-point (m > 3) second order boundary value problem (P_F\cal{P}_{F}) in a separable Banach space E of the form W ^{2, 1}_E([0, 1])W ^{2, 1}_E([0, 1])-solutions of (P_F\cal{P}_{F}) is compact and is a retract in C¹_E([0, 1])C^1_E([0, 1]). A new existence result of W ^{2, 1}_E([0, 1])W ^{2, 1}_E([0, 1])-solutions and a related relaxation problem are also provided, here F is no longer bounded.     

Experimental Study of Liquid Hydrocarbons Pyrolysis to Acetylene in H2/Ar Plasma

Liquid hydrocarbons including n-hexane, cyclohexane and toluene are pyrolyzed in H₂/Ar plasma to investigate the effects of feedstock properties and key operating conditions (e.g., the feedstock specific input power and residence time) on the reaction performance. The experiments verify that the non-aromatic hydrocarbons show better chemical reactivity than partially aromatic substances. Meanwhile, the straight-chain alkanes and cycloalkanes have better yields of ethylene during the pyrolysis. The results also demonstrate that the pyrolysis reactions are almost completed within the first 0.8?ms in Ar/H₂ plasma independent of the feed substances (i.e., liquid hydrocarbons), where the increased feedstock specific input power enhances the reactant conversions and correspondingly raises the yields of acetylene. At a feedstock specific input power of 4.7?×?10⁴?kJ/kg, the n-hexane conversion is over 90?% and the yield of acetylene reaches 70?%. In addition, when using n-hexane as the feedstock, very little coke is formed during the course of reaction. Comprehensive comparisons of the current experiments with the data reported in the literature are made to point out the key influencing factors, i.e., the effective mass ratio of C/H (R _C/H) in the gaseous phase and the quench temperature. Both two factors would need to be enhanced in order to get a better performance. Finally, the improvements on the specific energy requirement of this process are discussed.