Microbial transformations of buagarofuran,an anti-anxietic agent

19 structurally diverse metabolites (2–20) were isolated from the transformation of buagarofuran (1), an anxiety agent, by three filamentous fungal strains, Cunninghamella echinulata AS 3.3402, Cunninghamella elegans AS 3.3400, and Absidia coerulea AS 3.3538. Their structures and identified on the basis of extensive spectroscopic data (HRMS, NMR, IR, and CD) and chemical methods. All of the metabolites were oxidized products of 1, and metabolite 20 was also one of mammalian metabolites. Metabolites 8, 10–12, and 20 significantly inhibited [³H]-NE re-uptake, and 8 and 9 strongly inhibited [³H]-5-HT re-uptake in the rat brain synaptosomes at 10 μM in vitro. The structural diversity of the microbial transformed metabolites of buagarofuran in the present report would give a favorable opportunity to probe its mammalian metabolism and better shed light on its pharmacokinetics and pharmacodynamics in vivo.     

Multiphoton ionization spectroscopy in surface analysis and laser desorption mass spectrometry

The application of resonance-enhanced multiphoton ionization (REMPI) spectroscopy for the ultrasensitive detection of molecules originating from laser desorption experiments performed on a variety of substrates is reviewed. Laser-induced desorption from surfaces is capable of producing intact gas-phase molecules, even from polar, non-volatile, high-molecular-weight and thermally labile substances. REMPI is a highly efficient and optically selective ionization method, which, coupled with laser desorption allows the direct chemical analysis of complex mixtures, without the need for previous sample purification and separation steps. The use of REMPI spectroscopy is discussed in two contexts: (1) for the direct chemical analysis of complex mixtures, e.g., environmental samples, by laser desorption/laser postionization mass spectrometry and (2) for measurements of internal state distribution of molecules laser-desorbed from sub-monolayers surface films to gain insight into the laser desorption mechanism.Presented at the 13th International Symposium on Microchemical Techniques (ISM), held in Montreux, Switzerland, May 16–20,1994     

Rhodium-catalyzed Asymmetric Ring Opening Reaction of Oxabenzo-norbornadiene with Substituted Phenolic Nucleophiles

Among the myriad of molecular architectures present in pharmacological agents, certain structures emerge with a higher frequency than others. Among these “privileged structures” is the hydronaphthalene skeleton which can be found in a wide range of comp…     

渐变折射率Ta2O5/SiO2薄膜多脉冲激光损伤特性

采用离子束溅射（IBS）的方式,制备了1064 nm高反射Ta2O5/SiO2渐变折射率光学薄膜。对其光学性能和在基频多脉冲下抗损伤性能进行了分析。 通过渐变折射率的设计方式,很好地抑制了边带波纹,增加了1064 nm反射率。通过对损伤阈值的分析发现,随着脉冲个数的增加,损伤阈值下降明显;但是在20个脉冲数后,损伤阈值（维持在22 J/cm2左右）几乎保持不变直到100个脉冲数。通过Leica显微镜对损伤形貌的观察,发现损伤诱因是薄膜表面的节瘤缺陷。通过扫描电镜（SEM）以及聚集离子束（FIB）对薄膜表面以及断面的观察,证实了薄膜的损伤起源于薄膜表面的节瘤缺陷。进一步研究得出,渐变折射率薄膜在基频光单脉冲下损伤主要是由初始节瘤缺陷引起的,在后续多脉冲激光辐照下初始节瘤缺陷引起烧蚀坑的面积扩大扫过薄膜上的其他节瘤缺陷,引起了其他节瘤缺陷的喷射使损伤加剧,造成损伤的累积效应。     

Cleavage cracking across twin boundaries in free-standing silicon thin films

Cleavage cracking across twin boundaries in free-standing silicon thin films is investigated in a microtensile fracture experiment. If the twist misorientation is relatively small, the crack front transmission can be quite smooth; otherwise the fracture surface may be either planar or broken down into parallel terrains. In all the cases, the local fracture resistance tends to increase. PACS 62.20.-x; 68.35.bg; 68.35.Gy; 68.37.-d; 62.20.mm     

光学元件亚表面缺陷的全内反射显微检测

 光学元件亚表面缺陷的有效检测已成为高阈值抗激光损伤光学元件制造的迫切要求。基于全内反射照明原理开展了全内反射显微技术检测光学元件亚表面缺陷的实验研究。结果表明：全内反射显微技术可有效检测光学元件亚表面缺陷;入射光偏振态和入射角度会影响元件内界面下不同深度处驻波形式照明强度的分布,对于可见度发生明显改变的微小缺陷点能衡量出其一定的深度尺寸范围;利用显微镜精密调焦对界面下一定深度处缺陷成像,可知缺陷点的位置深度。     

Non-functionalized carbon nanotube binding with hemoglobin

Carbon nanotube has a high potential to be used as a biosensor and drug carrier. However, its binding behavior with proteins needs to be studied before the full potential of carbon nanotube in biological studies can be realized. Although many studies have been conducted to characterize the affinity of functionalized carbon nanotube to various types of proteins, our present study for the first time reported that hemoglobin can bind with non-functionalized carbon nanotube, and this binding can be identified by Raman spectrum. Further, this binding has not changed Raman luminescence with specific excitation and emission wavelengths. The immediate application of these findings is to use non-functionalized carbon nanotube as a biosensor to measure H(2)S in blood in which hemoglobin takes about 37% of the total blood volume. Other potential uses of non-functionalized carbon nanotube to bind selective groups of proteins are also hinted.