Electrochemical scanning tunneling microscopy and electrochemical quartz crystal microbalance study of the adsorption of phenanthraquinone accompanied by an electrochemical redox reaction on the Au electrode

In situ electrochemical scanning tunneling microscopy (ECSTM) and an electrochemical quartz crystal microbalance (EQCM) have been employed to follow the adsorption/desorption processes of phenanthraquinone (PQ sat. in 0.1 mol l(-1) HClO4, solution) accompanied with an electrochemical redox reaction on the Au electrode. The result shows that: (1) the reduced form PQH(2) adsorbed at the Au electrode and the desorption occurred when PQH(2) was oxidized to PQ; (2) the adsorption process initiates at steps or kinks which provide high active sites on the electrode surface for adsorption, and as the potential shifts to negative, a multilayer of PQH(2) may be formed at the Au electrode; (3) the reduced PQH(2) adsorbed preferentially in the area where the tip had been scanned continually; this result suggests that the tip induction may accelerate the adsorption of PQH(2) on the Au(111) electrode. Two kinds of possible reason have been discussed; (4) high resolution STM images show the strong substrate lattice information and the weak monolayer adsorbate lattice information simultaneously. The PQH(2) molecules pack into a not perfectly ordered condensed physisorbed layer at potentials of 0.1 and 0.2 V with an average lattice constant a = 11.5 +/- 0.4 Angstrom, b = 11.5 +/- 0.4 Angstrom, and gamma = 120 +/- 2 degrees; the molecular lattice is rotated with respect to the substrate lattice by about 23 +/- 2 degrees. (C) 1997 Elsevier Science S.A.

Self-assembly of the pre-formed inclusion complexes between cyclodextrins and alkanethiols on gold electrodes

A new kind of self-assembled monolayer (SAM) formed in aqueous solution through the pre-formed inclusion complexes (abbreviated CD . C-n) between alpha-, beta-cyclodextrins (CDs) and alkanethiols (CH3(CH2)(n-1)SH, n = 10, 14 and 18) was prepared successfully on gold electrodes. High-resolution H-1 NMR was used to confirm the formation of CD . C-n. X-ray photoelectron spectroscopy, cyclic voltammetry and chronoamperometry were used to characterize the resulting SAMs (denoted as M-CD . Cn). It was found that M-CD . Cn were more stable against repeated potential cycling in 0.5 M H2SO4 than SAMs of CH3(CH2)(n-1)SH (denoted as M-Cn), with a relative sequence of Mbeta-CD . Cn > Malpha-CD . Cn > M-Cn. In addition, an order of blocking the electron transfer between gold electrodes and redox couples (both Fe(CN)(6)(3-) and Ru(NH3)(6)(3+)) in solution, M-CD . C10 > M-CD . C14 > M-CD . C18, was observed. A plausible explanation is provided to elucidate some of the observations. (C) 1997 Elsevier Science S.A.

单醚二酐型聚醚酰亚胺的透气性能与分子结构之间关系的研究

合成了一系列单醚二酐型聚醚酞亚胺（ＰＥＩ），研究了它们对Ｈ２、ＣＯ２、Ｏ２、Ｎ２和ＣＨ４５种气体的透过性能与分子结构的关系．结果表明，这类聚醚欧亚胺的分子结构对其透气性和透气选择性有很大的影响，聚合物的自由体积和链段活动性是控制透气性和透气选择性的主要因素．二苯醚四酸二酐（ＯＤＰＡ－４．４＇－二Ｊ氨基二苯异丙烷（ＩＰＤＡ）具有很大的自由体积和较小的链段活动性、很大的透气性和较小的透气选择性，ＯＤＰＡ—４，４’－二氨基二苯酮（ＤＡＢＰ）具有很小的自由体积和较小的链段活动性、很小的透气性和较大的透气选择性，ＯＤＰＡ—３，３’－二甲基二苯甲烷二胶（ＤＭＭＤＡ）具有较大的自由体积和较小的链段活动性、很大的透气性和很大的透气选择性．

1-甲基-1,4,7,10-四氮杂环十二烷镧配合物的合成及晶体结构

合成了1-甲基-1,4,7,10-四氮杂环十二烷(L)配体。在乙腈中培养了La(L)(CH_3CN)-(H_2O)(CF_3SO_3)_3配合物单晶,测定了其红外光谱和质子核磁共振谱。用X射线衍射方法测定了配合物的晶体结构,该晶体属于单斜晶系,P2_1/n空间群,a=0.9700(2)nm,b=1.5966(2)nm,c=1.9085(1)nm,β=104.71(3)°,V=2.8588(50)nm~3。配合物中镧为9配位,其配位多面体为扭曲的单帽四方反棱柱体。

高聚物玻璃化转变温度和分子参数的关系 Ⅰ.高聚物链柔性与T_g的关系

本文采用晶格模型,以动力学链段长度作为统计单元大小,推导了高聚物玻璃化温度T_8和链静态刚性因子σ~2(T_8),链动态刚性因子β(T_8)以及聚合度DP等分子参数之间的关系。具体讨论了链柔性对T_8的影响。理论预测和几十种聚合物的实验数据能较好吻合,分析结果表明T_8值基本上取决于高聚物链σ(T_8)大小。

CDNA cloning and mRNA expression of the lipopolysaccharide- and beta-1,3-glucan-binding protein gene from scallop Chlamys farreri

Lipopolysaccharide and beta-1,3-glucan-binding protein (LGBP) play a crucial role in the innate immune response of invertebrates as a pattern recognition protein (PRP). The scallop LGBP gene was obtained from Chlamys farreri challenged by Vibrio anguillarum by randomly sequencing cDNA clones from a whole body cDNA library, and by fully sequencing a clone with homology to known LGBP genes. The scallop LGBP consisted of 1876 nucleotides with a canonical polyadenylation signal sequence AATAAA and a poly(A) tail, encoding a polypeptide of 440 amino acids with the estimated molecular mass of 47.16 kDa and a predicted isoelectric point of 5.095. The deduced amino acid sequence showed a high similarity to that of invertebrate recognition proteins from blue shrimp, black tiger shrimp, mosquito, freshwater crayfish, earthworms, and sea urchins, with conserved features including a potential polysaccharide-binding motif, a glucanase motif, and N-glycosylation sites. The temporal expression of LGBP genes in healthy and V. anguillarum-challenged C farreri scallop, measured by real-time semiquantitative reverse transcription polymerase chain reaction (PCR), showed that expression was up-regulated initially, followed by recovery as the stimulation cleared. Results indicated that scallop LGBP was a constitutive and inducible acute-phase protein that could play a critical role in scallop-pathogen interaction. (C) 2004 Elsevier B.V. All rights reserved.

The mitochondrial manganese superoxide dismutase gene in Chinese shrimp Fenneropenaeus chinensis: Cloning, distribution and expression

Manganese superoxide dismutase (MnSOD) plays an important role in crustacean immune defense reaction by eliminating oxidative stress. Knowledge on MnSOD at molecular level allows us to understand its regulatory mechanism in crustacean immune system. A novel mitochondrial manganese superoxide dismutase (mMnSOD) was cloned from hepatopancreas of Chinese shrimp Fenneropenaeus chinensis by 3' and 5' rapid amplification of cDNA ends (RACE) PCR. The full-length cDNA consists of 1185 bp with a 660 bp open reading frame, encoding 220 amino acids. The deduced amino acid sequence contains a putative signal peptide of 20 amino acids. Sequence comparison showed that the mMnSOD of F. chinensis shares 88% and 82% identity with that of giant freshwater prawn Macrobrachium rosenbergii and blue crab Callinectes sapidus, respectively. mMnSOD transcripts were detected in hepatopancreas, hemocytes, lymphoid organ, intestine, ovary, muscle and gill by Northern blotting. RT-PCR analysis indicated that mMnSOD showed different expression profiles in shrimp hemocytes and hepatopancreas after artificial infection with while spot syndrome virus (WSSV). In addition, a fusion protein containing mMnSOD was produced in vitro. LC-ESI-MS analysis showed that two peptide fragments (-GDVNTVISLAPALK- and -NVRPDYVNAIWK-) of the recombinant protein were identical to the corresponding sequence of M. rosenbergii mMnSOD, and the enzyme activity of the refolded recombinant protein was also measured. (c) 2006 Elsevier Ltd. All rights reserved.

Sea surface temperature reconstruction for the middle Okinawa Trough during the last glacial-interglacial cycle using C-37 unsaturated alkenones

C-37 unsaturated alkenones were analyzed on a core retrieved from the middle Okinawa Trough. The calculated U-37(K') displays a trend generally parallel with those of the oxygen isotopic compositions of two planktonic foraminiferal species, Neogloboquadrina dutertrei and Globigerinoides sacculifer, suggesting that in this region, SST has varied in phase with global ice volume change since the last glacial -interglacial cycle. The U-37(K')-derived SST ranged from ca. 24.0 to 27.5 degrees C, with the highest value 27.5 degrees C occurring in marine isotope stage 5 and the lowest similar to 24.0 degrees C in marine isotope stage 2. This trend is consistent with the continental records from the East Asian monsoon domain and the marine records from the Equatorial Pacific. The deglacial increase of the U-37(K')-derived SST is similar to 2.4 degrees C from the Last Glacial Maximum to the Holocene. (c) 2007 Elsevier B.V. All rights reserved.

海洋红藻多管藻和松节藻的化学成分及抗氧化活性研究

海洋生物具有产生丰富多样的次生代谢产物的能力，其中红藻门松节藻科海藻卤代次生代谢产物以其结构新颖、生物活性独特引起了天然产物化学家的重视。 本论文对海洋红藻多管藻和松节藻进行了化学成分研究，综合利用各种色谱学方法 (硅胶柱层析、反相硅胶柱层析、凝胶Sephadex LH-20柱层析、半制备高效液相色谱以及重结晶等) 和现代波谱学技术 (IR、UV、EI-MS、FAB-MS、HR-ESI-MS、CD、1H-NMR、13C-NMR、DEPT、1H-1H COSY、HSQC、HMBC等)，共分离鉴定了100个化合物，发现25个新化合物。 从多管藻中分离鉴定38个化合物 (24个溴酚化合物)，其中7个新化合物 (均为溴酚化合物)，包括1个菲并呋喃结构溴酚 (P1), 2个二氢菲结构溴酚 (P2, P3)，1个含 5,7-dihydrodibenzo[c,e]oxepine 结构溴酚 (P4)和3个简单溴酚 (P5, P6, P7)。P1 (urceolatin) 属首例报道的具有菲并呋喃结构的天然产物，从该种中分离的化合物P12 和 P13 可能是其生源合成的前体。P2和P3为第二例报道的具有二氢菲结构的溴酚化合物。 从松节藻中分离并鉴定了62 个化合物，其中18 个为溴酚类新化合物，44 个为已知化合物。化合物具有多变的取代基团，包括2 个脲基吡咯烷酮溴酚化合物 (R1, R2), 4 个γ-脲基丁酸溴酚化合物 (R3-R6)，5 个酰胺溴酚化合物 (R7, R8, R9, R13, R14)，1 个溴酚砜化合物 (R12), 1 个Xanthene 溴酚化合物 (R10)和5 个简单溴酚化合物 (R11, R15, R16, R17, R18)。R1、R2 是首例报道的含有脲基吡咯烷酮片段的天然产物，R10 为首次报道的溴代Xanthene 类天然产物。 对分离到的化合物进行了清除DPPH 和ABTS两种自由基活性的筛选。结果发现溴酚类天然产物具有显著的DPPH自由基清除活性，其中R3 的IC50 仅为3.3 μM, 其活性强度约为阳性对照BHT (IC50 为82.1 μM) 的24倍。另外，溴酚类天然产物对ABTS自由基有较强的清除活性，R2 的TEAC（Trolox efficency activity capacity）值为5.2 mM，约为阳性对照 (ascorbic acid, 1.02 mM) 的 5 倍。初步的构效关系研究发现，稠环分子、多羟基和邻位甲氧基等结构特点能有效增强DPPH 自由基清除活性；特殊取代基如脲基、吡咯烷酮等含有氮原子的基团，能有效增强ABTS 自由基清除活性，多羟基、溴代等结构特点也使其活性有所增强。 本研究结果丰富了海藻卤代化合物的结构类型，为多管藻和松节藻的合理利用提供了一定的科学依据。

趋磁细菌AMB-1培养条件优化及磁小体变化过程研究

趋磁细菌(Magnetotactic bacteria)的研究是国际微生物学研究热点之一。趋磁细菌体内含有纳米单磁畴的氧化铁/硫化铁(Fe3O4或Fe3S4)晶体，称为磁小体。由于趋磁细菌营养条件要求苛刻，在环境中需要微好氧条件，且营养类型属于化能自养，使得培养趋磁细菌时常遇到问题。 本研究首先通过正交试验优化趋磁细菌AMB-1菌株培养条件，在培养条件铁源为奎尼酸铁0.02 mmol/L，装瓶量75% ，pH值6.7，温度25 ℃时，AMB-1 OD600达到0.440(1.166×109 cells/ml)。同时运用磁收集传代法，使带有磁小体的AMB-1细胞比例占95％以上(Cmag值稳定在1.9-2.0)。 在AMB-1具有较好的生物量，同时又具有较好的含磁小体细胞比例后，研究磁小体的变化过程。通过透射电镜观察磁小体变化过程，发现培养24 h细菌体内已有较小晶体形成(平均27 nm，n=188)且沿长轴分布；48 h晶体长大(平均43 nm，n=203)且形成分段链沿长轴排列；72 h晶体进一步成熟(平均50 nm，n=191)仍以分段链沿长轴排列；随后细菌逐渐衰亡磁小体变小，168 h可见部分自溶细菌中仍有磁小体链(平均37 nm，n=186)；192 h细菌自溶磁小体链(平均33 nm，n=184)分散到环境中。 通过透射电镜在细胞水平上研究趋磁细菌细胞分裂时发现，磁小体在细菌分裂时采用两种分离方式：一种为磁小体分配到两个子细胞；另一种为磁小体只分配到一个子细胞。无磁小体的子细胞，在随后的生长过程又分为两种情况：一种为细胞逐渐产生磁小体，另一种为不再产生磁小体。这种现象的发现，解释了随着传代次数的增多，细菌磁性有所下降的原因(Cmag值降低)。 在对趋磁细菌磁小体合成机制的研究中，常使用基因敲除的办法获得缺陷型，并与野生型对比进行研究。但是，利用基因敲除获得缺陷型不仅操作繁琐并且所得缺陷型不稳定。本研究利用特殊的磁富集传代法，先将带有磁小体的菌体收集并连续传代，筛选获得了高磁菌株；利用这种方法，收集不含磁小体的菌体并连续传代，筛选获得了无磁菌株。 趋磁细菌磁小体在医疗、环保等领域具有广阔应用价值，但是目前由于趋磁细菌难以大规模培养，并且磁小体纯化存在成本高等原因，将磁小体真正实际应用尚有一段距离。通过研究磁小体在趋磁细菌中的变化过程发现，AMB-1菌株在培养192 h后自溶，并且磁小体随着细胞的破碎释放到环境中去。

Fluorescence Characterization of Dissolved Organic Matter in East China Sea

Sea water samples were collected in the East China Sea in March and April, 2005, and three-dimensional fluorescence of dissolved organic matter was measured by fluorescence excitation-emission matrix spectroscopy. The position, number and intensity of fluorescence peak in the spectra and the relations of the peaks were analyzed to determine the type, distribution and origin of the fluorescence dissolved organic matter. Seven types of fluorescence peaks were detected from the samples. There are protein-like fluorescence peaks B with Ex(max)/Em(max) = 275/300 nm, D with Ex(max)/Em(max) = 225/295-305 nm, T with Ex(max)/Em(max) = 280/345 nm, and S with Ex(max)/Em(max) = 225-240/320-350 nm, two humic-like peaks A with Ex(max)/Em(max) = 250-255/410-455 nm and C 335-345/410-440 ran, and marine humic peak M with Ex(max)/Em(max) = 305 nm/400-420 nm. Peaks B, S and A appeared in all surveyed area. Peaks T and D appeared in the north of the surveyed area. Peaks M and C only appeared in a few stations. In the surface layer, the source of the fluorescence dissolved organic matter might be the fresh water outflow of the Yangtze River, while the fluorescence dissolved organic matter in the middle layer had double sources from the Yangtze River and the phytoplankton. The good correlationships of different fluorescence peaks showed the same source or some relationship between the protein-like and the humic-like fluorescence dissolved organic matter.

高寒灌丛草甸生态系统CO2释放的初步研究

以金露梅(Potentilla fruticosa)灌丛草甸生态系统为对象，应用静态密闭箱-气相色谱法对高寒灌丛(GG)、丛内草甸(GC)和裸地(GL)的CO2释放进行了初步研究。结果表明：GG、GC和GL CO2的释放速率均呈明显的单峰型日变化进程，最大释放速率出现在15：00～17：00之间，最小值在7：00前后出现，白天释放速率大于夜晚；CO2释放速率具有明显的季节性变化特征，生长期CO2释放速率明显高于枯黄期，且均表现为正排放，8月为CO2释放高峰期，释放速率GG>GC>GL(P<0．01)；2003年6月30日至2004年2月28日，高寒灌丛植被-土壤系统CO2释放量为3088．458±287．02g／m^2，丛内草甸植被-土壤系统CO2释放量为2239．685±183．68g／m^2，其中基础土壤呼吸CO2的释放量约为1346．748±176．24g／m^2，分别占GG和GC释放量的43．61％和60．13％；CO2释放速率的日变化主要受地表和5cm地温制约，而季节动态与5cm地温呈显著正相关关系(P<0．01)。

Analysis of primary aromatic amines using precolumn derivatization by HPLC fluorescence detection and online MS identification

2-(2-Phenyl-1H-phenanthro-[9,10-d]imidazole-1-yl)-acetic acid (PPIA) and 2-(9-acridone)-acetic acid (AAA), two novel precolumn fluorescent derivatization reagents, have been developed and compared for analysis of primary aromatic amines by high performance liquid chromatographic fluorescence detection coupled with online mass spectrometric identification. PPIA and AAA react rapidly and smoothly with the aromatic amines on the basis of a condensation reaction using 1-ethyl-3-(3dimethylaminopropyl)-carbodiimide (EDC) as dehydrating catalyst to form stable derivatives with emission wavelengths at 380 and 440 nm, respectively. Taking six primary aromatic amines (aniline, 2-methylaniline, 2-methoxyaniline, 4-methylaniline, 4-chloroaniline, and 4-bromoaniline) as testing compounds, derivatization conditions such as coupling reagent, basic catalyst, reaction temperature and time, reaction solvent, and fluorescent labeling reagent concentration have also been investigated. With the better PPIA method, chromatographic separation of derivatized aromatic amines exhibited a good baseline resolution on an RP column. At the same time, by online mass spectrometric identification with atmospheric pressure chemical ionization (APCI) source in positive ion mode, the PPIA-labeled derivatives were characterized by easy-to-interpret mass spectra due to the prominent protonated molecular ion m/z [M + H](+) and specific fragment ions (MS/MS) m/z 335 and 295. The linear range is 24.41 fmol-200.0 pmol with correlation coefficients in the range of 0.9996-0.9999, and detection limits of PPIA-labeled aromatic amines are 0.12-0.21 nmol/L (S/N = 3). Method repeatability, precision, and recovery were evaluated and the results were excellent for the efficient HPLC analysis. The most important argument, however, was the high sensitivity and ease-of-handling of the PPIA method. Preliminary experiments with wastewater samples collected from the waterspout of a paper mill and its nearby soil where pollution with aromatic amines may be expected show that the method is highly validated with little interference in the chromatogram.

HPLC-APCI-MS determination of free fatty acids in Tibet folk medicine Lomatogonium rotatum with fluorescence detection and mass spectrometric identification

A simple and sensitive method for the determination of free fatty acids (FFAs) using acridone-9-ethyl-p-toluenesulfonate (AETS) as a fluorescence derivatization reagent by high performance liquid chromatography (HPLC) has been developed. Free fatty acid derivatives were separated on an Eclipse XDB-C-8 column with a good baseline resolution and detected with the fluorescence of which excitation and emission wavelengths of derivatives were set at lambda(ex) 404 and lambda(em) 440 nm, respectively. Identification of 19 fatty acid derivatives was carried out by online post-column mass spectrometry with an atmospheric pressure chemical ionization (APCI) source under positive-ion detection mode. Nineteen FFAs from the extract of Lomatogonium rotatum are sensitively determined. The results indicate that the plant Lomatogonium rotatum is enriched with an abundance of FFAs and FFAs of higher contents, which mainly focus on even carbon atoms, C-14, C-16, and C-18. The validation of the method including linearity, repeatability, and detection limits was examined. Most linear correlation coefficients for fatty acid derivatives are > 0.9989, and detection limits (at signal-to-noise of 3: 1) are 12.3-43.7 fmol. The relative standard deviations (RSDs) of the peak areas and retention times for 19 FFAs standards are < 2.24% and 0.45%, respectively. The established method is rapid and reproducible for the separation determination of FFAs from the extract of Lomatogonium rotatum with satisfactory results.

黄铁矿热转变过程的岩石磁学研究

Pyrite is the most stable iron-sulfide in reduced environment, and plays an important role in geochemical iron-sulfur cycling of sediments. Thus, the presence of pyrite in sediments and rocks is an important indicator of sedimentary environments. Previous studies on the thermal products of pyrite showed that all of the products (e.g., pyrrhotite, magnetite, hematite) have strong capability of carrying remanence. To deepen our understanding of the environmental and paleomagnetic significances of pyrite, the mineral transformation processes of pyrite upon heating were systematically investigated in this study using intergrated rock magnetic experiments (in both argon and air atmospheres) and X-ray diffraction analysis. The room temperature susceptibility of the paramagnetic pyrite is about 2.68×10-5 SI. In argon atmosphere (reducing environment), pyrite was transformed into monoclinic stable single domain (SD) pyrrhotite above 440 C. The corresponding coercive force and remanence coercivity are about 20 mT and 30 mT, respectively. In contrast, in air atmosphere (oxidation environment), the intermediate thermal products of pyrite are magnetite and pyrrhotite, which were quickly further oxidated to SD hematite, which has coercivity of about 1400 mT. In addition, the hematite particles gradually grow from SD to PSD grain size region by multiple heating runs. The transformation processes of pyrite in oxidation atomosphere can be interpreted by three possible pathways: (1) pyrite→magnetite→hematite; (2) pyrite→pyrrhotite→magnetite→hematite; and (3) pyrite→pyrrhotite→hematite. Low-temperature magnetic experiments show no transitions for pyrite. Despite that low-temperature magnetic method is not suitable for identification of pyrite, it is clear in this study that the high-temperature thermomagnetic measurements (e.g.,  -T and J-T curves) are very sensitive to the presence of pyrite in sediments and rocks. Nevertheless, for the thermal treatment products, low-temperature magnetic measurements showed the 34 K transition of pyrrhotite and the 250 K Morine transition of hematite. Iron-sulfide has also been found on Martian meteorolites by other workers. Therefore, systematic study of rock magnetism of pyrite (and other iron-sulfides) and their products will have great significances for both paleomagnetism and planetary magnetism.