铕（II）等低价稀土离子在氧化物基质中光谱特征及其变化规律

近年来，围绕低价稀土离子开展的研究工作越来越多，尤其重视铕(II)、钐（II）和镱(II)的研究，以期获得短波可调固体激光晶体或高效率发光材料。由于4f~n到4f~(n-1)5d'组态的d-f跃迁是属于宇称允许的跃迁，所以它的发射要比4f~n壳层内的受迫电偶极跃迁强得多。这可以保证对泵浦的有效吸收，提高光泵效率。而4f~n组态内部的f-f锐线发射可以实现激光振荡，有利于提高储能，降低阀值。所以深入了解4f~n和 4f~(n-1)5d'体系在基质晶场中的行为以及基质环境对稀土离子发光特征的影响，对于寻找和设计新的激光和发光材料有着极为重要的意义。 本文从理论上讨论了晶场效应和化学键性质对铕(II)、钐(II)等稀土离子发光性质的影响。采用高温固相反应的方法合成了一系列铕(II)、钐(II)激活的氧化物基质荧光材料。结合光谱实验数据建立了晶格环境对铕(II)的 4f~65d'能级影响的表观模型和定量计算公式。为了研究4f~65d'激发态的性质，我们采用改进的Slater法计算了铕(II)和配体氧的有关轨道能量。利用静电晶场模型讨论了4f~65d'能带劈裂幅度(△E)与Eu-O键距(R)的关系，量子化学计算表明5d能级在晶场中的劈裂(△E)与R~5成反比。碱金属和碱七金属磷酸盐基质中铕的光谱数据证实了上述结论。在该基质中铕的4f~65d'能带的劈裂幅度随Eu-O键距增加而变小。在MeSO_4:Eu~(2+) (Me = Ca, Sr，Ba)中，随碱七金属离子半径增大，其发射和激发截止波长均有规律地向短波区移动。这是由于当铕(II)占据较大半径阳离子格位时，将受到较小的晶场影响。其体系的荧光寿命数据也证实了这一点。运用统计热力学原理讨论了4f~(n-1)5d'与 4f~n激发态能级的相对位置对低价稀土离子d-f和f-f跃迁发射的影响。在Ba_(1-x)Mg_(1+x)(SO_4):Eu~(2+)中，适当增大Mg~(2+)离子含量，线一带两种发射强度比R = I (f-f)/I(d-f) 明显增大。Ba_(0.4)Mg_(1.6)(SO_4)_2:Eu~(2+)的f-f锐线发射强度最大。在Ba_(1-x)Sr_xMg(SO_4)_2:Eu~(2+)中，铕(II)的f-f强度随x增大而变小，d-f发射峰则随x增加而发生红移。运用“电子云扩展效应”和鲍林化学键原理解释了，在Na_(3-x)(PO_4)_(1-x)(SO_4)_x:Eu~(2+)和Na_(2-x)CaSi_(1-x)P_xO_4:Eu~(2+)体系中，随X值在固溶区内变大，铕(II)的发射光谱逐渐移向短波区的现象。为了研究稀七离子的取代格位对其光谱性质的影响，我们合成了K_2Mg_2(SO_4)_3:Eu~(2+)单晶化合物。并经四圆衍射仪解出了结构。铕(II)在单晶中占据Mg_1~(2+)格位，与KMgF_3:Eu~(2+)相比，它将受到更强的晶场作用使4f~65d'能带劈裂幅度变大，又通过计算可知，Eu-O键的共价性比Eu-F键更强，因而在K_2Mg_2(SO_4)_3中Eu~(2+) 4f~65d'重心更低一些。综上所述，K_2Mg_2(SO_4)_3:Eu~(2+)的发射能级(E_(em)~m)要比KMgF_3:Eu~(2+)的发射能级更低。光谱实验数据证实了这一结论。用245 nm激发， K_2Mg_2(SO_4)_3:Eu~(2+)发兰光，最大中心处于400 nm。而KMgF_3:Eu~(2+)发紫色或近紫外光(E_(em)~m = 363 nm)，并且在后者是观察到Eu~(2+)离子的f-f跃迁锐线发射。采用高温氢气还原法制备了SmF_2和SmCl_2作为离子激活源。钐(II)激活的硫酸盐材料的荧光光谱数据表明，在室温条件下该基质中钐(II)的荧光光谱均为4f~55d' → 4f~6跃迁的宽带发射。论文对铕(II)，钐(II)等低价稀土离子的4f~(n-1)5d'激发态性质和稀七离子在基质中的格位取代以及电荷补偿效应也作了较为详细的讨论。

超高灵敏显色反应及其应用的研究

本论文“超高灵敏显色反应及其应用的研究”包括五部分内容：一 文献综述对超高灵敏显色反应、有新机理及其在光度分析中的应用作全面的评述。二 汞（II）－乙基罗丹明B－碘化物体系光度法测定痕量汞仍是常用的方法之一。但是其灵敏度尚待进一步提高，文献中报导测汞最灵敏的罗丹明B光度法ε值为5.44*10~5。本工作研究了汞（II）－乙基罗丹明B－碘化物体系和光度特性。缔合物最大吸收峰位于605nm，表观摩尔吸光系数为1.14*10~6 L.mol~(-1)-cm~(-1)。缔合物可稳定近1小时。汞（II）含量在0.1-2.5μg/25ml时服从比耳定律。试验了17种共存离子的影响，并应用联合掩蔽剂消除干扰。本法可不经分离起直接用于水样分析或经巯基棉分离用于地球化学标样中痕量汞的分析，获得较满意的结果。检测下限为1ppb（湖水，100ml）。三 锑（III）－乙基罗丹明B－碘化物体积以碱性染料萃取光度法测定锑、已有很久历史，但是这类方法存在灵敏度低，操作繁琐，使用有机溶剂等缺点。文献极导最灵敏的水相光度法ε值为3.4*10~5。本工作研究了锑（III）－乙基罗丹明B－碘化物系和光度特性。缔合物λ_(max)=605nm.表观摩尔吸光系数为7.0*10~5 l·mol~(-1)·cm~(-1)。锑浓度在0.1-2.5μg/25ml时服从比耳定律。体系可稳定近1个小时。借助于氢化物发生法分离并富集痕量锑，方法应用于水系沉积物标样中锑的测定，结果与推荐值相符。检测下限为1*10~(-5)％(1g样品)。四 铅（II）－乙基罗丹明B－碘化物体积铅是环保、医药等部门常需检测的有害元素之一。但是，目前光度法测定铅，灵敏度最高者为ε=5.7*10~5，尚待进一步提高。本工作研究了铅（II）－乙基罗丹明B－碘化物体系及光度特性。缔合物λ_(max)=605nm，表观摩尔吸光系数为10*10~6 L·mol~(-1)·cm~(-1)。铅浓度在0.1-3.0μg/25ml时服从比耳定律。缔合物可稳定半小时。试验了22种共存离子的影响，借助于巯基棉分离，本法可用于试剂中铅的测定，结果和对照值一致，检测下限为1*10~(-5)％(1g样品)。五 缔合物形成机理的研究本工作通过吸收光谱研究及缔合物组成比的测定，对显色反应的机理作了初步研讨。吸收光谱研究证明：水溶性大分子PVA_(124)并不参与缔合物组成，它主要是对缔合物起分散和稳定作用；并证实在不同条件下，有两种缔合物形成：R_2(HgI_4)(λ_(max)=587nm)和复杂缔合物(λ_(max)=605nm)。用摩尔比法及等摩尔连续变化法测得组成比为Hg:R=1:14和Sb:R=1:9。这是一种新型的显色反应，推测其反应机理可能是以简单缔合物 [ERB~+]_2·[HgI_4~(-2)]或 [ERB~+]_2·[sbI_5~(-2)]值点为核心，在R~+和I~-浓度较高的条件下，籍范德华力再吸附几个ERB~+I~-缔合物分子形成一种高染料配比的吸附型复杂缔合物，其化学式可能为[（ERB~+）_2·（HgI_4~(-2)]·12[ERB~·I~-]和[（ERB~+）_2·（sbI_5~(-2)]·7[ERB~·I~-]本类超高灵敏显色体系的反应机理十分复杂，影响因素众多，不同作者曾提出过一些看法，但大多缺乏实验根据。本类缔合物的稳定性较差，是深入研究其反应机理的主要困难，尚待继续努力。

对金属稀土金属有机配合物的合成、结构及催化性质研究

合成出三类18种双金属稀土金属有机配合物：第一类：Ln-Li双金属π－烯丙基稀土配合物－LiLn(π-C_3H_5)_4 nD(Ln=La、Tb, n=3; Ln=Y、Dy, n=2.5; Ln=Ce、Pr、Nd、Sm、Gd、Er, n=2; D=二氧六环）。第二类：Ln-Mg双金属π－烯丙基稀土配合物-(π-C_3H_5)_2CnCl_5Mg_2(tmed)_2 (Ln=Ce、Nd)和(π-C_4H_7)_2LnCl_5Mg_2(tmed)_2 (Ln=La、Ce、Nd; C_4H_7=i-C_4H_7)。第三类：Ln-Al双金属配合物－[(CF_3CO_2)_3LnHAlR_2·2THF]_2 (Ln=Y、Nd, R=i-Bu; Ln=Eu, R=Et)。用四园X－ray衍射仪在低温下测定了LiCe(π-C_3H_5)_4·4D、[(CF_3CO_2)_3YHAl(i-Bu)_2 2THF]_2、[(CF_3CO_2)_3NdHAl(i-Bu)_2 2THF]_2和[(CF_3CO_2)_3EuHAlEt_2·2THF]_2的晶体结构。对[(CF_3CO_2)_3YHAl(i-Bu)_2·2THF]_2和LiLn(π-C_3H_5)_4 nD类配合物进行了较详细的NMR研究。二维C－H相关NMR谱表明在[(CF_3CO_2)_3YHAl(i-Bu)_2·2THF]_2配合物中6个CF_3CO_2~-有2个羰基的C与H成键，该结果解释了Ln-Al双金属配合物中相应羰基的非平面结构现象。研究表明LiLn(π-CC_3H_5)_4·nD可催化异戊二烯和苯乙烯均聚合；不同配合物中均以Y配合物的活性为最高。(π-C_3H_5)_2CeCl_5Mg_2(tmed)_2对异戊二烯、丁二烯、苯乙烯以及甲基丙烯酸甲酯（MMA）的聚合有较低的催化活性；(π-C_4H_7)_2LnCl_5Mg_2(tmed)_2也对苯乙烯和异戊二烯的聚合有一定的催化活性。分别以LiCe(π-C_3H_5)_4·4D和(π-C_3H_5)_2CeCl_5Mg_2(tmed)_2作为稀土配位催化剂的模型配合物，研究了其催化所得聚异戊二烯的端基结构。表明聚合物均具有烯丙基端基(-CH_2-CH=CH_2)。证明单体在Ce~(3+)和π－烯丙基之间发生了插入反应，聚合按π－烯丙基机理进行。该结果首次为稀土配位催化共轭双烯烃聚合的活性链端π－烯丙基机理提供了直接的实验证据。(π-C_3H_5)_2CeCl_5Mg_2(tmed)_2-Al(i-Bu)_3(Al/Ce(摩尔比)=4))体系对异戊二烯的聚合具有较高的催化活性，所得聚合物仍具有－CH_3-CH=CH_2端基，而没有i-Bu端基。该结果又一次为上述π-烯丙基机理提供了直接的实验证据。发现Ln(CF_3CO_2)_3-AlEt_3体系可催化THF开环聚合。首次实现稀土催化THF开环聚合。研究了Y(CF_3CO_2)_3-HAl(i-Bu)_2-ECH（环氧氯丙烷）体系催化THF开环聚合法性及聚合机理。讨论了各种聚合条件对该体系催化活性的影响。研究了[(CF_3Co_2)YHAl(i-Bu)_2·2THF]_2在ECH存在下催化THF聚合活性并认为该双金属配合物为Y(CF_3CO_2)_3-HAl(i-Bu)_2-ECH体系的活性体。[(CF_3CO_2)_3YHA(i-Bu)_2·2THF]_2和[(CF_3CO_2)_3EuHAlEt_2·2THF]_2均可催化ECH和MMA聚合，所得PMMA的间同(rr)含量可达76.5％。

东北地区不同小麦品种对黑麦草的化感作用

以东北地区33个不同来源的小麦品种为研究对象,采用琼脂共培法,评价了不同小麦品种对黑麦草所产生的化感作用.通过分析不同小麦品种对黑麦草根长、苗高、根干重及苗干重的影响,探讨不同小麦品种对黑麦草化感作用的差异,从而筛选出具有较强化感潜力的小麦品种.结果表明,不同小麦品种对黑麦草根长、苗高、根干重及苗干重的影响存在显著差异.利用R I值作为化感作用的指标,结合聚类分析方法,可将这33个小麦品种按化感能力的强、中、弱分成3类;其中龙幅麦9号、龙幅麦13号、锦麦2003和小冰麦33号为化感能力较强的品种.

Synthesis and characterization of the titanium complexes bearing two regioisomeric trifluoromethyl-containing enaminoketonato ligands and their behavior in ethylene polymerization

A series of new titanium complexes bearing two regioisomeric trifluoromethyl-containing enaminoketonato ligands (3a-h and 6a-h), [PhN=CRCHC(CF3)O](2)TiCl2 (3a, R = Me; 3b, R = n-C5H11; 3c, R = i-Pr; 3d, R = Cy; 3e, R = t-Bu; 3f, R = CH=CHPh; 3g, R = Et; 3h, R = n-C11H23) and [PhN=C(CF3)CHC(R)O](2)TiCl2 (6a, R = Ph; 6b, R = n-C5H11; 6c, R = i-Pr; 6d, R = Cy; 6e, R = t-Bu; 6f, R = CH=CHPh; 6g, R = CHPh2; 6h, R = CF3) have been synthesized and characterized. X-ray crystal structures analyses suggest that complexes 3c-e and 6c-d all adopt a distorted octahedral geometry around the titanium center. Complexes 3c, 3d and 6c display a cis-configuration of the two chlorine atoms around the titanium center, while complex 6d shows a trans-configuration of the two chlorine atoms. Especially, the configurational isomers (cis and trans) of complex 3e were identified both in solution and in the solid state by NMR and X-ray analyses. With modified methylaluminoxane as a cocatalyst, all the complexes are active towards ethylene polymerization, and produce high molecular weight polymers.

Synthesis, structure and luminescence properties of zinc (II) complexes with terpyridine derivatives as ligands

Five zinc (II) complexes (1-5) with 4 '-phenyl-2,2 ':6 ',2 ''-terpyridine (ptpy) derivatives as ligands have been synthesized and fully characterized. The para-position of phenyl in ptpy is substituted by the group (R), i.e. tert-butyl (t-Bu), hexyloxy (OHex), carbazole-9-yl (Cz), naphthalen-1-yl-phenyl-amine-N-yl (NPA) and diphenyl amine-N-yl (DPA), with different electron-donating ability. With increasing donor ability of the R, the emission color of the complexes in film was modulated from violet (392 nm) to reddish orange (604 nm). The photoexcited luminescence exhibits significant solvatochromism because the emission of the complexes involves the intra-ligand charge transfer (ILCT) excited state. The electrochemical investigations show that the complexes with stronger electro-donating substituent have lower oxidation potential and then higher HOMO level. The electroluminescence (EL) properties of these zinc (II) complexes were studied with the device structure of ITO/PEDOT/Zn (II) complex: PBD:PMMA/BCP/AlQ/ LiF/Al. Complexes 3, 4 and 5 exhibit EL wavelength at 552, 600 and 609 nm with maximum current efficiency of 5.28, 2.83 and 2.00 cd/A, respectively.

Syntheses and crystalline structures of clusters Co-3(CO)(7)(mu(3)-S)(mu, eta(2)-SCNR2)

Through the reaction of Co-2(CO)(8) with four thiuram [R2NC(S)S](2), four new sulfur-capped trinuclear cobalt carbonyl clusters Co-3 (CO)(7) (mu(3)-S) (mu, eta(2)-S* C* NR2) ( I : R = Me; I : R = Et; II : R = i-Pr; IV : NR= -N [GRAPHICS] were prepared and characterized by elementary analysis, IR,H-1 NMR and MS spectroscopy. The crystal structure of the cluster Co-3(CO)(7)(mu(3)-S)[mu, eta(2)-S*C*N (i-Pr)(2)]( III) was determined by X-ray single crystal diffraction method. The crystal of m is monoclinic, belonging to space group P2(1)/n, and the cell parameters are as follows: a = 1, 145 2(2) nm, b = 1. 502 8(3) nm, c = 1, 214 4(2) nmj alpha = 90 degrees, beta = 92, 15(3)degrees, gamma = 90 degrees; V = 2. 088 5(7) nm(3) , Z = 4, F (000) = 1 096, D-c = 1. 747 mg . m(-3), mu = 2. 588 mm(-1), R=0. 040 7, R-w=0. 062 4, The structural analysis shows that cluster II has a pyrimidal Co3S framework and contains a heterocylic bridging bidentate ligand [mu, eta(2)-S* C* N (i-Pr)(2)] linked to the Co2 and Co3 atoms of the cluster by a cobalt-carbon and a cobalt-sulfur bond respectively.

Co_3(CO)_7(μ_3-S)(μ,η~2-SCNR_2)的合成和晶体结构

Co2 (CO) 8 与 4个二硫代双 (烷基硫代甲酰胺 )类前配体 [R2 NC(S) S]2 反应 ,得 4个含烷基硫代甲酰胺基的三核钴羰基硫簇合物 .通过元素分析、IR、 1H NMR和 MS等方法表征了它们的结构 ,用 X射线衍射法测定了其中一个簇合物 Co3 (CO) 7(μ3 - S) [μ,η2 - SCN(i- Pr) 2 ]( )的晶体结构 .晶体属单斜晶系 ,P2 1/n空间群 ,晶胞参数 a=1.1452 (2 ) nm,b=1.50 2 8(3) nm,c=1.2 144 (2 ) nm,α=90°,β =92 .15(3)°,γ =90°,V =2 .0 885(7) nm3 ,Z=4 ,F (0 0 0 ) =10 96 ,Dc=1.74 7mg· m-3 ,GOF(F2 ) =0 .835,μ=2 .588nm-1.最终因子 R[I>2 σ(I) ]=0 . 0 4 0 7,Rw=0 .0 6 2 4

Synthesis of lanthanide-alkylaluminium bimetallic complexes and studies on their catalytic activities for polymerization of some polar monomers

Three new lanthanide (Ln)-alkylaluminium (Al) bimetallic complexes with the formula [(mu-CF3CO2)(2)Ln(mu-CF3CHO2)AIR(2) . 2THF](2) (Ln = Nd, Y, R=i-C4H9 (i-Bu); Ln=Eu, R=C2H5(Et); THF=tetrahydrofuran) were synthesized by the reaction of Ln(CF,CO,), (Ln=Nd, Y) with HAI (i-Bu)(2) and of Eu(CF3CO2)(3) with AlEt(3), respectively. Their crystal structures were determined by X-ray diffraction at 233 K. [(mu-CF3CO2)(2)Nd (mu-CF3CHO2)Al(i-Bu)(2) . 2THF](2) (Nd-Al) and [(mu-CF3CO2)(2)Y(mu-CF3CHO2)Al(i-Bu)(2) . 2THF](2) (Y-Al) are isomorphous and crystallize in space group with a=12.441(3) Angstrom [12.347(5) Angstrom for Y-Al], b=12.832(3) Angstrom [12.832(4) Angstrom], c=11.334(3) Angstrom [11.292(8) Angstrom], alpha=104.93 (2)degrees [104.45(4)degrees], beta=98.47(2)degrees [98.81(4)degrees], gamma=64.60(2)degrees [64.30(3)degrees], R=0.519 [0.113], R(w)=0.0532 [0.110], Z=1 and [(mu-CF3CO2)(2)Eu(CF3CHO2)AlEt(2) . 2THF](2)(Eu-Al) in space group P2(1)/n with a=11.913(6) Angstrom, b=14.051(9) Angstrom, c=17.920(9) Angstrom, alpha=101.88(11)degrees, beta=gamma=90 degrees, R=0.0509, R(w)=0.0471 and Z=2. The six CF3CO2- (including CF3CHO2-) of each complex, among which pairs are equivalent, coordinated to Ln and Al in three patterns: (A) the two oxygen atoms in one of the three CF3CO2- type coordinated to two different Ln; (B) the two oxygen atoms in the second of CF3CO2- type coordinated to Ln and Al, respectively; (C) one of the two oxygen atoms in the third CF3CO2- type bidentately coordinated to two Ln and another oxygen coordinated to Al and one of the two Ln, respectively. Unlike types A and B, in type C the carboxyl carbon with a hydrogen atom bonded to it was found to appear as an sp(3)-hybridized configuration rather than an sp(2)-one. 1D and 2D NMR results further confirmed the existence of such a disproportionated CF3CHO2- ligand. Methyl methacrylate (MMA) and epichlorohydrin (ECH) could be polymerized by Y-Al or Eu-Al as a single-component catalyst and highly syndiotactic poly(MMA) was obtained. THF could also be polymerized by Y-Al in the presence of a small amount of ECH.

SYNTHESES AND CHARACTERIZATION OF [(MU-CF3CO2)(2)LN(MU-CF3CHO2)ALR(2)CENTER-DOT-2THF](2) AND THEIR CATALYTIC ACTIVITIES FOR POLYMERIZATION OF SOME POLAR MONOMERS

Three new bimetallic complexes were synthesized and crystalized by reactions of (CF3CO2)(3)Ln With R(1) AlR(2)(Ln=Nd and Y, R(1)=H, R=i-C4H9; Ln=Eu, R=R(1)=C2H5) in tetrahydrofuran solution, and their crystal structures were determined using a X-ray diffraction method. The structures and the questions on valence state and noncoplanarity in the structures were confirmed and cracked by means of H-1 NMR and C-13 NMR spectra, especially by C-13-H-1 COSY 2D NMR technique. A general formula of molecules of the three rare earth complexes was defined as follows: [(mu-CF3CO2)(2)Ln(mu-CF3CHO2)AlR(2) . 2THF](2) A mechanism on the formation of the new complexes was also proposed through the following five steps: alkylating, beta-elimination (or hydrogenation), hydrogen transfer, linkage and association. Both Y-Al and Eu-Al complexes function as a catalyst in polymerization of MMA and ECH. The polymer obtained from the first monomer is mainly syndiotactic chain structure and the polymerization of the last monomer shows higher catalytic activity. The Y-Al complex also capable of ring-opening polymerization of THF in case of adding-vary small amount of ECH and a oxonium ion mechanism of THF polymerization was suggested from the analysis of THF polymer terminal.

[(μ-CF_3CO_2)Ln(μ-CF_3CHO_2)AIR_2·2THF]_2的合成和表征及其对某些极性单体的催化活性

通过(CF_3CO_2)_3Ln(Ln=Nd、Y和Eu)和R~1AlR_2(R~1=H,R=i-C_4H_9;R~1=R=C_2H_5),反应首次合成和培养出Nd-Al、Y-Al和Eu-Al三种新的双金属稀土配合物和晶体,并用X射线衍射法测定出它们的晶体结构,然后再用二维波谱技术,进一步证实和完善了晶体结构中的价态和非共面现象.由此确定这三种稀土配合物分子式的通式为:[(μ-CF_3CO_2)_2Ln(μ-CF_3CHO_2)AlR_2·2THF]_2.根据实验结果还提出了通过烷基化、β-消除(或氢化)、氢转移、键合及缔合等五个步骤生成这些配合物的反应机理.这些配合物单独可使MMA和ECH催化聚合,前者可获得主要以间同结构聚合物,后者聚合催化活性较高,在极少量的ECH存在下,还可使THF开环聚合,并通过PTHF端基分析,提出了(钅羊)离子聚合反应机理.

Strong High Pressure Systems Influencing the Weather in Poland During the Period 1971-2000

This paper shows preliminary results of research into the occurrence of strong anticyclonic systems that influenced the weather in Poland during the period 1971–2000. The study was based on NCEP/NCAR reanalysis data, including daily values of the 1000 and 500 hPa geopotential heights, maps of mentioned geopotential heights and maps of sea-level field pressure. With the use of these data a number of exceptionally strong high-pressure systems were identified, together with their areas of origin and subsequent development patterns. They were then broken down into five groups with similar dynamics. The numbers of systems in each group were not found to follow any significant change trends in the long term. The greatest differences between groups were identified in terms of their annual occurrence rates and centre pressure values.

Contribution to the knowlegde of Galician xenoflora (NW Iberian Peninsula, Spain).

Information on 12 exotic plants of diverse interest for the Galician flora are presented. All of them were collected in Ribeira council (SW of the A Coruña province). The total includes 8 novelties at a regional level (Aeonium haworthii, Aloe mitriformis, Brugmansia × candida, Nephrolepis cordifolia, Osteospermum ecklonis, Pelargonium capitatum, Sedum mexicanum, Sparaxis tricolor), and 2 provincial novelties. In addition, information on two taxa hardly mentioned in the literature on Galician vascular flora is also included. All the cited specimens are deposited at the SANT Herbarium.

Diversity of functional groups in the vegetation sandy seashore of the Grande, Anclitas and Caguamas Cays (Jardines de la Reina Archipelago, Cuba)

Sandy shores are known to be extreme ecosystems where the vegetation has evolved many morphological and physiological adaptations for its survival. With the aim of identify possible relationships between the vegetation´s functional diversity with abiotic factors and its corresponding quantification, we collected data on the abundance and richness of the sandy coast vegetation complex in Grande, Anclitas and Caguamas keys. Its flora is largely characterized by the dominance of hemicryptophytes and chamaephytes plants with nanophyllous leaves and displaying dispersal syndromes such as zoochory and anemochory. However, the functional groups´ richness, in the present study, varies from one key to another. Functional diversity is similar between the wet and dry seasons, and its spatial variation is influenced by the interplay of the set of abiotic factors herein studied.

Photometry of cometary nuclei: Rotation rates, colours and a comparison with Kuiper Belt Objects

We present time-series data on Jupiter Family Comets (JFCs) 17P/Holmes, 47P/Ashbrook-Jackson and 137P/Shoemaker-Levy 2. In addition we also present results from `snap-shot' observations of comets 43P/Wolf-Harrington, 44P/Reinmuth 2, 103P/Hartley 2 and 104P/Kowal 2 taken during the same run. The comets were at heliocentric distances of between 3 and 7 au at this time. We present measurements of size and activity levels for the snap-shot targets. The time-series data allow us to constrain rotation periods and shapes, and thus bulk densities. We also measure colour indices (V - R) and (R - I) and reliable radii for these comets. We compare all of our findings to date with similar results for other comets and Kuiper Belt Objects (KBOs). We find that the rotational properties of nuclei and KBOs are very similar, that there is evidence for a cut-off in bulk densities at ~0.6 g cm-3 in both populations, and the colours of the two populations show similar correlations. For JFCs, there is no observational evidence for the optical colours being dependent on either position in the orbit or orbital parameters.