High-density comparative BAC mapping in the black muntjac (Muntiacus crinifrons): Molecular cytogenetic dissection of the origin of MCR 1p+4 in the X1X2Y1Y2Y3 sex chromosome system

The black muntjac (Muntiacus crinifrons, 2n = 8 female/9 male) is a critically endangered mammalian species that is confined to a narrow region of southeastern China. Male black muntjacs have an astonishing X1X2Y1Y2Y3 sex chromosome system, unparalleled i

Formation, structure and fluorescence of CdS clusters in a mesoporous zeolite

CdS clusters are formed in the pores of a mesoporous zeolite in which the size of the clusters may be adjusted. The size of the clusters increases as the CdS loading is increased. X-ray diffraction investigation shows that the lattice constants of the clusters contract upon increasing size. This contraction is attributed to an increase of the static pressure exercised by the zeolite framework as the clusters grow bigger. Both the excitonic and trapped emission bands are detected and become more intensive upon decreasing size. Three absorption bands appear in the photoluminescence excitation (PLE) spectra and they shift to the blue as cluster size decreases. Based on the effective-mass approximation, the three bands are assigned to the 1S-1S, 1S-1P and 1S-1D transitions, respectively. The size-dependence of the PLE spectra can also be explained. (C) 1997 Elsevier Science Ltd.

聚合物共混体系的相容性及基固核磁共振研究

本工作对几个不同类型的聚合物/聚合物共混体系-PS/SBR，EVA/CPE，PVF_2/PEMA和PMAA/PEO-的相容性和共混物中分子基团的相互作用进行了探讨和研究。主要结果有：（1）对不同PS分子量的PS/SBR聚合物共混体系进行了形态观察和Tg测量，结果表明共混物的相容性随PS组分的分子量、组成和温度变化。（2）用固体NMR测量进一步证实了EVA/CPE是分子之间均匀混合的相容共混体系。T_1值在测试温度范围内都符合自旋强相互作用偶合的加和式。（3）对PVF_2/PEMA共混体系进行了固体NMR研究，测量得到~1H的T_1和T_2随温度的变化曲线，用PC/MAS技术得到共混体系的高分辨~(13)C MNR谱，并从各个化学位移峰强对交叉极化接触时间的变化曲线拟合得到不同基团的~1H T_(1p)和T_(CH)。（4）用二维NMR技术通过质子自旋交换相互作用，考察了聚电解质与水溶性聚合物的共混物PMAA/PEO中各个化学基团之间的空间接近程度。

Photoluminescence of ZnS clusters in zeolite-Y

Two obvious emissions are observed from the ZnS clusters encapsulated in zeolite-Y. The emission around 355 nm is sharp and weak, locating at the onset of the absorption edge. The band around 535 nm is broad, strong and Stokes-shifted. Both the two emissions shift to blue and their intensities firstly increase then decrease as the loading of ZnS in zeolite-Y or clusters size decreases. Through investigation, the former is attributed to the excitonic fluorescence, and the latter to the trapped luminescence from surface states. The cluster size-dependence of the luminescence may be explained qualitatively by considering both the carrier recombination and the nonradiative recombination rates. Four peaks appearing in the excitation spectra are assigned to the transitions of 1S-1S, 1S-1P, 1S-1D and surface state, respectively. The excitation spectra of the clusters do not coincide with their absorption spectra. The states splitted by quantum-size confinement are detected in the excitation spectra, but could not be differentiated in the optical absorption spectra due to inhomogeneous broadening. The size-dependence of the excitation spectra is similar to that of the absorption spectra. Both the excitation spectra of excitonic and of trapped emissions are similar, but change in relative intensity and shift in position are observed.

中子核和铅区核的结构研究

我们首先用Woods-Saxon势对一些丰中子核进行了系统的计算．计算表明在Woods-Saxon势中考虑一个对称能项，Woods-Saxon势就能够很好的描述丰中子核的密度分布，单粒子能级结构和中子质子的均方根半径．用Woods Saxon势的计算结果表明中子皮是丰中子远离β稳定线核的普遍现象。2S1/2轨道与1d 5/2轨道的交又和2s1d壳与1p壳的壳崩渍是中子晕形成的重要原因，也是中子晕与中子皮的一个重要区别．壳模型的计算能够很好的再现9《A《14和3《Z《5丰中子核的许多性质，这表明了，改进壳模型的有效相互作用，壳模型可能能够描述远离核的性质． 我们208Ti一类核和206Pb的一些性质进行了系统的壳模型计算．计算结果表明，K-H和SDI等有效相互作用对描述208Ti一类核和206Pb的高激发态仍然是有效的，计算结果也表明，如果208Hg可供利用的β衰变能比206Hg小，则可以预计208Hg的半寿命比206Hg要长.计算还证实了在反应209Bi（ρ，a )206Pb中激发的206Pb激发态结构，与205Tl低激发态结构相似，即这些态可以用h9/2轨道上的一个质子与205T1的低激发态的弱耦合来描述，此即所谓的对应的相似多重态的概念． 最后，我们对11Li等中子晕核的束缚机制提出了一种新的关联机制和讨论了用壳模型描述集体运动的方法．

反刍动物的比较分子细胞遗传学研究

1. 反刍动物核型演化研究 反刍亚目是偶蹄目中最大的亚目，包括鼷鹿下目(鼷鹿科)和有角下目(叉角 羚羊科、长颈鹿科、麝科、牛科和鹿科)。许多物种具有巨大的经济价值（如： 牛，羊，鹿和麝，等）和重要的科学研究价值（如麂类动物）。对反刍动物进行 细胞遗传学研究，不仅可以为动物遗传育种和驯化提供重要的理论依据和合理 建议，也可以为生物演化等基础科学研究提供新的见解和理论阐释。种间染色 体涂色可以快速、准确地检测物种间全基因组水平上的同源性，已经成为比较 细胞遗传学研究的首选技术。通过构建物种间的染色体同源图谱，分析保守的 同源染色体片段在不同物种、不同类群核型中的分布和排列方式，可以推导各 类群可能的祖先核型并重建伴随物种形成所发生的基因组结构变化(包括染色 体重排的类型、速率和核型演化的趋势等)，为系统发育关系研究提供重要的细 胞遗传学证据。 本研究首次通过种间染色体涂色技术，利用小麂染色体特异探针，大规模 建立了小麂与牛科、鹿科及长颈鹿科代表物种间的染色体同源关系，阐明了其 核型演化中所发生的染色体重排，并以染色体重排为特征，构建了反刍动物各 类群的核型系统发生树。结果表明：1) 有角下目动物的共同祖先核型为2n=58， 牛科2n=60 的祖先核型和鹿科2n=70 的祖先核型都由共同祖先核型经过染色体 分离演化而来；2）与鹿科动物的核型相比，麝科动物与牛科动物的核型比较保 守，更接近共同祖先的核型，二者共有更多的核型特征；3）在有角下目的绝大 多数类群中，罗伯逊易位是导致核型多样化的主导染色体重排方式；鹿科的麂 亚科是个例外，染色体间不断地串联融合使其核型发生了迅速而极端的变化, 导致现生各种极大的核型差异；4）长颈鹿的核型演化较为复杂，除了广泛的罗 伯逊易位外，还涉及到其它类型的染色体重排，如，着丝粒位置变化、串联融 合及染色体内部倒位。现在，黄牛的基因组序列已拼接完毕，鹿、羊的基因组 测序正在进行，本论文中构建的反刍动物间的染色体同源图谱有助于将已有的基因组序列信息向其它反刍动物转移。 2. 麂属动物染色体演化研究 鹿科的麂属动物以快速的物种辐射、迅速而极端的核型演化和不断的新种 发现成为染色体重排与物种形成研究的理想模型。已有的细胞遗传学研究证明 麂属动物的祖先核型为2n=70，染色体间的串联融合是导致其核型迅速演化， 染色体数目急剧降低的主要原因。但是，关于麂属动物核型演化，还有很多问 题没有解决，如，黑麂、贡山麂、费氏麂核型演化中串联融合的类型没有确定， 导致串联融合的分子机制依然不清楚。 本研究利用比较BAC 定位技术首次构建小麂－黑麂、小麂－贡山麂、小麂 －费氏麂、小麂－毛冠鹿染色体间的比较BAC 图谱，研究结果丰富和发展了“串 联融合假说”的内容，对麂属动物的核型演化提出了新的阐释：1）在毛冠鹿、 黑麂、贡山麂和费氏麂的核型演化中所发生的串联融合均为着丝粒－端粒型融 合；2）黑麂1p+4 染色体的演化大体经历了三个步骤，主要涉及染色体易位和 臂间倒位；1p+4 的存在使雄性黑麂具有独特的X1X2Y1Y2Y3 性染色体系统， 1p+4 可以看作新的Y染色体(neo-Y),将是哺乳动物性染色体起源研究的理想模 型； 3）黑麂、贡山麂和费氏麂各自有独特而稳定的基因组结构和核型特征， 支持它们各自为独立的种。此外，实验中筛选出的70 个麂类着丝粒特异的或 C5 样的重复序列克隆将有助于研究麂类基因组中重复序列的类型、组成、结构、 演化及导致串联融合频繁发生的分子机制.

Potential P limitation leads to excess N in the pearl river estuarine coastal plume

There is excess nitrate (NO3) in the Pearl River coastal plume in the southern waters of Hong Kong in summer. We hypothesize that phosphorus (P) limitation controls the utilization of excess NO3 due to the high N:P ratio in the Pearl River. To test this hypothesis, we conducted two 1-day cruises on July 13 and 19, 2000 to examine the response of the phytoplankton to P additions with respect to changes in biomass, uptake of nutrients and nutrient uptake ratios using a batch incubation of natural water samples collected from the Pearl River estuary and adjacent coastal waters. At a station (E1, salinity =5) in the Pearl River estuary, the N/P ratio at the surface was 46:1, (64 muM DIN: 1.3 muM PO4) and decreased to 24:1 (12 muM DIN: 0.5 muM PO4) downstream at a station (Stn 26, salinity =26) in the coastal plume south of Hong Kong. Without a P addition, NO3 in the water samples collected at E1 could not be depleted during a 9 day incubation (similar to20 muM NO3 remaining). With a P addition, NO3 disappeared completely on day 6 with the depletion of the added PO4 (2-3 muM). This was also true for a station, E4 (salinity= 15) further downstream, but within the estuary. At Stn 26, in the coastal plume south of Hong Kong, NO3 (similar to11.5 muM) was eventually depleted without the addition of PO4, but it took 8 days instead of 5 days for Stn E4. The uptake ratio of dissolved inorganic nitrogen (DIN) to PO4, without a P addition was 51:1, 43:1 and 46:1 for Stns E1, E4 and 26, respectively. With a P addition, the DIN/PO4 uptake ratio decreased to 20:1, 14:1 and 12:1, respectively, for the 3 stations. These results clearly indicate potential P limitation to utilization of NO3 in the Pearl River estuary, resulting in excess NO3 in waters of the coastal plume downstream of the estuary, some of which would eventually be transported offshore. High uptake ratios of N:P without a P addition (43N:1P) suggest that phytoplankton have a nitrogen uptake capacity in excess of the Redfield ratio of 16N: 1P by 2.5-3 times. The value of 2.5-3 times was likely a maximum that should have contained a contribution of P released from desorption of P from sediments or from regeneration by zooplankton grazing and bacterial activity during the incubation of natural water samples. Without a P addition, however, phytoplankton biomass did not increase. This means that P turnover rates or regeneration may allow phytoplankton to take up additional N in excess of the Redfield ratio and store it, but without increasing the algal biomass. Therefore, high ambient N:P ratios in excess of the Redfield ratio do indicate potential P limitation to phytoplankton biomass in this estuarine coastal ecosystem. (C) 2004 Elsevier Ltd. All rights reserved.

Epoxidation of propylene with dilute H2O2 over titanium silicalite containing trace aluminum

Titanium silicalite (TS-1) was successfully synthesized by using TPABr as the template and silica sol as silicon source in a 100 l stainless steel autoclave. IR, XRD, UV--vis, elemental analysis, and (2)7Al and (3)1P MAS NMR were used to characterize the synthesized products. The results show that the synthesized material has an MFI structure with high crystallinity and large crystal size and two kinds of titanium species. Trace aluminum in silica sol is also incorporated into the zeolite framework. The synthesized TS-1 exhibits high activity in the epoxidation of propylene with dilute H2O2 with high selectivity to methyl mono-ethers and low selectivity to propylene oxide (PO). The low selectivity toward PO is due to the residual acidity onto TS-1. The selectivity of PO can reach up to 90% through adjusting the pH of the reaction mixture. Extra amounts of base decrease the H2O2 utilization and the H2O2 conversion. However, in over acid-treated TS-1 in which part removal of extra-framework titanium takes place, the utilization of H2O2 is quite different: for the low Si/Ti ratio of TS-1, the H2O2 utilization increases. But the utilization of H2O2 does not change for the high Si/Ti ratio TS-1. Thermal analysis shows that the as-synthesized TS-1 exhibits high activity and thermal stability in the calcined range 540-900 degreesC.