Laurendecumallenes A-B and laurendecumenynes A-B, halogenated nonterpenoid C-15-Acetogenins from the marine red alga Laurencia decumbens

Four new halogenated nonterpenoid C-15-acetogenins, 4:7,6:13-bisepoxy-9,10-diol-1,12-dibromopentadeca-1,2-diene (1, laurendecumallene A), 4:7,6:12-bisepoxy-9,10-diol-1,13-dibromopentadeca-1,2-diene (2, laurendecumallene 13), (3Z)-6:10,7:13-bisepoxy-12-bromo-9-hydroperoxylpentadeca-3-en-1-yne (3, laurendecumenyne A), and (3Z)-6:10,9:13-bisepoxy-12-bromo-7-chloropentadeca-3-en-1-yne (4, laurendecumenyne 13), together with one known halogenated C-15-acetogenin elatenyne (5) were isolated and identified from the organic extract of the marine red alga Laurencia decumbens. Their structures and relative stereochemistry were established by means of spectroscopic analysis including UV, IR, high-resolution electrospray ionization mass spectrometry (HRESIMS), and ID and 2D NMR techniques. All these metabolites were submitted for the cytotoxic assay against tumor cell line A549 (human lung adenocarcinoma), but all of them were found inactive (IC50 > 10 mu g/mL).

滤食性贝类对浅海养殖系统生源要素动态的影响

在浅海养殖系统中，生源要素的形态和动态对滤食性贝类生长有着重要影响，与此同时，滤食性贝类对系统中的生源要素的动态也具有重要作用，国外学者对此研究的比较多，但在我国研究甚少。在本论文中利用室内模拟实验和海上调查的方法，研究滤食性贝类的生物过滤、生物沉积及排泄作用对浅海养殖系统中生源要素动态的影响。室内模拟实验部分：1998年4月至6月间，在烟台利用室内规格相同的水池，建立了栉孔贝扇（Chlamys farreri）不同养殖密度单养、栉孔扇贝和海带（Laminaria japonica）混养、栉孔扇贝和海带、刺参（Apostichopus japonicus）多元化养殖等三种养殖模式，九个养殖系统和一个对照系统，实验中各池的温度、光照、盐度和换水量基本一致，定期测定实验池中颗粒有机碳（POC）、颗粒氮（PN）和水体及沉积物中营养盐的含量。实验结果表明：1 栉孔扇贝大量滤食水体中的颗粒物质，导致水体中颗粒物质浓度的降低，水体中POC和PN的现存量与栉孔扇贝的放养密度负相关，水体中颗粒物的缺乏会限制栉孔扇贝的生长，当POC、PN的现存量分别降低到0.09mg/L、0.015mg/L时，就会限制栉孔扇贝的生长。2 栉孔扇贝排泄代谢产物增加了水体中无机营养盐的浓度，栉孔扇贝排泄的氮以NH_4~+-N为主，占三氮的93.5%；海带可为栉孔扇贝生长提供一部分饵料。3 实验期间硅浓度低于或近于2umol/L，限制了硅藻的生长，实验后期水体中氮盐浓度降低，氮磷比小于10，可能限制了浮游植物的生长，减少了栉孔扇贝的饵料生物，从而抑制了栉孔扇贝的生长。4 在栉孔扇贝单养和贝藻参混养系列中，沉积物中有机物、有机碳、有机氮、有机磷及总磷的含量随栉孔扇贝放养密度的增大而减少。5 在贝藻混养系列中的栉孔扇贝生长好于单养系列，在贝藻参混养系列中的海带生长速度快于贝藻混养系列；单养和贝藻参混养模式中栉栉孔扇贝的日产量均以放养密度中等的（20个/m~2）养殖系统较高。海上调查部分：于1997年冬季、1998年春季和夏季，在烟台四十里湾海区进行了三次野外调查，分别在养殖海区和非养殖海区取得沉积物柱状样，测定沉积物中有机质和间隙水中无机营养盐的含量。实验结果表明：6 养殖区沉积物中有机质的含量大于非养殖区，平均高约22%。7 养殖海区沉积物间隙水中营养盐的浓度大于非养殖海区，其中养殖区NH_4~+-N、PO_4~(3-)-P 的浓度分别高于非养殖区50%和200%-400%，NO_3~--N, NO_2~--N 的浓度差别不明显；沉积物间隙水中营养盐浓度冬季较小，而春夏季浓度较高；氮盐以NH_4~+-N 为主，占90%以上。8 养殖海区沉积物－海水界面间营养盐扩散通量大于非养殖海区，烟台四十里湾沉积物－海水界面间NH_4~+-N, PO_4~(3-)-P, NO_3~--N, NO_2~--N 冬、春、夏三季平均扩散通分别为249.99 umol/m~2/d、3.78 umol/m~2/d、5.24 umol/m~2/d、0.83mol/m~2/d。

白水剖面黄土-红粘土化学风化的粒度效应

The loess-red clay deposit in the Loess Plateau, as large regions mixed in the dust depositional areas, may recorded the chemical weathering features and recycling of the detritus material of the earth’s surface from the wide range upwind of the Loess Plateau. And the loess-red clay sequence is rare information for recovering the continent's weathering history of Late Cenozoic, as it’s clear sense of age. The concentrations of elements in loess-red clay are largely affected by grain size. Therefore, we divided samples of a long loess-red clay section and six spacial sections into three fractions in order to counteracting the effect of particle size on the values of weathering proxies. First, the loess unit L1 and S1 of six sections located at Guyuan, Baishui, Changwu, Yongshou, Yangling and Lantian, Chinese Loess Plateau were sampled. These samples were divided into three fractions: <5μm, 5-20μm, 20-63μm, which were then analyzed for the primary elements using an X-ray fluorescence analyser. Results show that the effect of particle is much smaller on the fraction <5μm than other fractions. Therefore, the fraction <5μm can reflect the change of chemical weathering intensity much better. In addition, we divided Baishui section samples into three fractions, and analyzed them with X-ray fluorescence for primary elements. Results show that the value of CIA vary in different size fractions, indicating different weathering progress. Elements K, Na, Ca and Mg in the <5μm fraction have a sequence which is the reverse of Bowen Sequence. This may be a important sense for the change of source regions.

Liquid alumina: detailed atomic coordination determined from neutron diffraction data using empirical potential structure refinement

Greaves, George; Jenkins, T.E.; Landron, C.; Hennet, L., (2001) 'Liquid alumina: detailed atomic coordination determined from neutron diffraction data using empirical potential structure refinement', Physical Review Letters 86 pp.4839-4842 RAE2008

Czy Europa umiera – nasz głos w dyskusji

Autorzy artykułu wskazują na poszczególne słabe punkty, czy też wady integracji europejskiej, rozważając jednocześnie przyszłą wizję Europy, jej pozycję w międzynarodowych i globalnych stosunkach oraz koncepcje budowy wspólnych struktur bezpieczeństwa. Artykułu oparty jest na założeniu, że Europa potrzebuje powtórnej, otwartej analizy jej problemów – symptomów przeobrażeń XXI wieku.

Skin Color-Based Video Segmentation under Time-Varying Illumination

A novel approach for real-time skin segmentation in video sequences is described. The approach enables reliable skin segmentation despite wide variation in illumination during tracking. An explicit second order Markov model is used to predict evolution of the skin-color (HSV) histogram over time. Histograms are dynamically updated based on feedback from the current segmentation and predictions of the Markov model. The evolution of the skin-color distribution at each frame is parameterized by translation, scaling and rotation in color space. Consequent changes in geometric parameterization of the distribution are propagated by warping and resampling the histogram. The parameters of the discrete-time dynamic Markov model are estimated using Maximum Likelihood Estimation, and also evolve over time. The accuracy of the new dynamic skin color segmentation algorithm is compared to that obtained via a static color model. Segmentation accuracy is evaluated using labeled ground-truth video sequences taken from staged experiments and popular movies. An overall increase in segmentation accuracy of up to 24% is observed in 17 out of 21 test sequences. In all but one case the skin-color classification rates for our system were higher, with background classification rates comparable to those of the static segmentation.

Investigations into selective metabolic aspects of bifidobacteria: carbohydrate metabolism, fatty acid biosynthesis and plasmid biology

The gastrointestinal tract (GIT) is a diverse ecosystem, and is colonised by a diverse array of bacteria, of which bifidobacteria are a significant component. Bifidobacteria are Gram-positive, saccharolytic, non-motile, non-sporulating, anaerobic, Y-shaped bacteria, which possess a high GC genome content. Certain bifidobacteria possess the ability to produce conjugated linoleic acid (CLA) from linoleic acid (LA) by a biochemical pathway that is hypothesised to be achieved via a linoleic isomerase. In Chapter two of this thesis it was found that the MCRA-specifying gene is not involved in CLA production in B. breve NCFB 2258, and that this gene specifies an oleate hydratase involved in the conversion of oleic acid into 10-hydroxystearic acid. Prebiotics are defined as non-digestible food ingredients that beneficially affect the host by selectively stimulating growth and/or activity of one or a limited number of bacteria in the colon. Key to the development of such novel prebiotics is to understand which carbohydrates support growth of bifidobacteria and how such carbohydrates are metabolised. In Chapter 3 of this thesis we describe the identification and characterisation of two neighbouring gene clusters involved in the metabolism of raffinose-containing carbohydrates (plus related carbohydrate melibiose) and melezitose by Bifidobacterium breve UCC2003. The fourth chapter of this thesis describes the analysis of transcriptional regulation of the raf and mel clusters. In the final experimental chapter two putative rep genes, designated repA7017 and repB7017, are identified on the megaplasmid pBb7017 of B. breve JCM 7017, the first bifidobacterial megaplasmid to be reported. One of these, repA7017, was subjected to an in-depth characterisation. The work described in this thesis has resulted in an improved understanding of bifidobacterial fatty acid and carbohydrate metabolism, Furthermore, attempts were made to develop novel genetic tools.

Visual memory loss and autobiographical amnesia: a case study.

Amnesia typically results from trauma to the medial temporal regions that coordinate activation among the disparate areas of cortex that represent the information that make up autobiographical memories. We proposed that amnesia should also result from damage to these regions, particularly regions that subserve long-term visual memory [Rubin, D. C., & Greenberg, D. L. (1998). Visual memory-deficit amnesia: A distinct amnesic presentation and etiology. Proceedings of the National Academy of Sciences of the USA, 95, 5413-5416]. We previously found 11 such cases in the literature, and all 11 had amnesia. We now present a detailed investigation of one of these patients. M.S. suffers from long-term visual memory loss along with some semantic deficits; he also manifests a severe retrograde amnesia and moderate anterograde amnesia. The presentation of his amnesia differs from that of the typical medial-temporal or lateral-temporal amnesic; we suggest that his visual deficits may be contributing to his autobiographical amnesia.

A dynamic mechanical method for determining the silicone elastomer solubility of drugs and pharmaceutical excipients in silicone intravaginal drug delivery rings

The silicone elastomer solubilities of a range of drugs and pharmaceutical excipients employed in the development of silicone intravaginal drug delivery rings (polyethylene glycols, norethisterone acetate, estradiol, triclosan, oleyl alcohol, oxybutynin) have been determined using dynamic mechanical analysis. The method involves measuring the concentration-dependent decrease in the storage modulus associated with the melting of the incorporated drug/excipient, and extrapolation to zero change in storage modulus. The study also demonstrates the effect of drug/excipient concentrations on the mechanical stiffness of the silicone devices at 37°C.