氢和硫原子在Pd、Au和Cu及PdAu、PdCu合金(111)表面吸附的密度泛函研究

用密度泛函理论研究了氢和硫原子在金属Pd、Au、Cu以及合金PdM3、Pd2M2和Pd3M(111)表面的吸附(M=Au,Cu),得到了覆盖率为0.25时最稳定的吸附位、结合能以及吸附前后表面的驰豫情况.结果表明,氢和硫均与Pd形成最稳定的吸附,Cu次之,Au的吸附最弱,其在三种纯金属(111)表面的最稳定吸附位均为fcc位.由于PdAu合金具有较大的晶格常数,Pd3Au合金吸附氢的结合能甚至较纯Pd更大,除此之外,氢和硫在PdM合金表面的吸附基本随M组分的增加而减弱,而最稳定的吸附位随金属种类和组成变化而变化.根据计算得到的吸附结合能,发现与PdCu合金相比,PdAu合金在Au含量较低(<25%,摩尔分数)时,氢和硫吸附的结合能下降较慢,而Au含量较高(>50%)时,结合能迅速下降,这表明含金量为25%-50%的PdAu合金有可能在保持相近透氢性能的同时,比PdCu合金具有更好的抗硫毒性.

In Vitro Anti-influenza Virus Activities of Sulfated Polysaccharide Fractions from Gracilaria lemaneiformis

In this paper, in vitro anti-influenza virus activities of sulfated polysaccharide fractions from Gracilaria lemaneiforrnis were investigated. Cytotoxicities and antiviral activities of Gracilaria lemaneiformis polysaccharides （PGL）, Gracilaria lemaneiformis polysaccharide fraction-1 （GL-1）, Gracilaria lemaneiformis polysaccharide fraction-2 （GL-2） and Gracilaria lemaneiformis polysaccharide fraction-3 （GL-3） were studied by the Methyl thiazolyl tetrazolium （MTT） method, and the inhibitory effect against Human influenza virus H1-364 induced cytopathic effect （CPE） on MDCK cells were observed by the CPE method. In addition, the antiviral mechanism of PGL was explored by Plaque forming unit （PFU）, MTT and CPE methods. The results showed： i） Cytotoxicities were not significantly revealed, and H1-364 induced CPE was also reduced treated with sulfated polysaccharide fractions from Gracilaria lemaneiformis; ii） Antiviral activities were associated with the mass percentage content of sulfate groups in polysaccharide fractions, which was about 13%, in polysaccharides （PGL and GL-2） both of which exhibited higher antiviral activity; iii） A potential antiviral mechanism to explain these observations is that viral adsorption and replication on host cells were inhibited by sulfated polysaccharides from Gracilaria lemaneiformis. In conclusion, Anti-influenza virus activities of sulfated polysaccharide fractions from Gracilaria lemaneiformis were revealed, and the antiviral activities were associated with content of sulfate groups in polysaccharide fractions

Synthesis and antiviral bioactivities of novel chiral bis-thiourea-type derivatives containing α-aminophosphonate moiety

Starting from 1-((1R,2R)-2-aminocyclohexyl)-3-substituted thioureas (3a–c) and substituted isothiocyanates (9a–d),chiral bis-thiourea derivatives containing α-aminophosphonate moiety 10a–l were prepared and completely characterized by elemental analysis,physical and spectral (IR,1H NMR,13C NMR,31P NMR) data.The results of bioassay revealed that compounds 10a and 10e possessed appreciable curative bioactivities on cucumber mosaic virus (CMV) at 0.5 mg/mL in vivo (inhibitory rate = 60.3%,64.8% respectively) and tobacco mosaic virus (TMV) at 0.5 mg/mL in vivo (inhibitory rate = 50.3%,50.8% respectively),which were comparable to the values shown by standard reference (58.7%) and commercial product Ningnanmycin (56.3%),respectively.Chiral compound 10e displayed more potent antiviral activity (EC50 = 0.149 mg/mL) than Ningnanmycin (EC50 = 0.201mg/mL) against CMV.