A thermodynamic and crystallographic study of complexes of the highly preorganized ligand 8-hydroxyquinoline-2-carboxylic acid

The metal ion complexing properties of the ligand HQC (8-hydroxyquinoline-2-carboxylic acid) are reported. The structures of [Zn(HQCH)₂] · 3H₂O (1) and [Cd(HQCH)₂] · 3H₂O (2) were determined (HQCH = HQC with phenol protonated). Both 1 and 2 are triclinic, space group , with Z = 2. For 1 a = 7.152(3), b = 9.227(4), c = 15.629(7) Å,  = 103.978(7)°, β = 94.896(7)°, γ = 108.033(8)°, R = 0.0499. For 2 a = 7.0897(5), b = 9.1674(7), c = 16.0672(11) Å,  = 105.0240(10)°, β = 93.9910(10)°, γ = 107.1270(10)°, R = 0.0330. In 1 the Zn has a distorted octahedral coordination geometry, with Zn–N of 2.00 and 2.15 Å, and Zn–O to the protonated phenolic oxygens of 2.431 and 2.220 Å. The structure of 2 is similar, with Cd–N bonds of 2.220 and 2.228 Å, with Cd–O bonds to the protonated phenolate oxygens of 2.334 and 2.463 Å. The structures of 1 and 2, and isomorphous Ni(II) and Co(II) HQC complexes reported in the literature, show very interesting short (<2.5 Å) O–O distances in H-bonds involving the protons on the coordinated phenolates and lattice water molecules. These are discussed in relation to the possible role of short low-energy H-bonds in alcohol dehydrogenase in mediating the transfer of the hydroxyl proton of the alcohol to an adjacent serine oxygen.

The formation constants for HQC are determined by UV–Visible spectroscopy at 25 °C in 0.1 M NaClO₄ with Mg(II), Ca(II), Sr(II), Ba(II), La(III), Gd(III), Zn(II), Cd(II), Ni(II), Cu(II), and Pb(II). These show greatest stabilization with metal ions with an ionic radius above 1.0 Å. This is as would be expected from the fact that HQC forms two five-membered chelate rings on complex-formation, which favors larger metal ions. The ligand design concept of using rigid aromatic backbones in ligands to achieve high levels of preorganization, and hence the high log K values (for a tridentate ligand) and strong metal ion selectivities observed for HQC, is discussed.     

SOME REMARKS ON CHENJIAWO FAUNA──On the First Appearance of Peking Man Fauna

I.CORRELATIONBETWEENL0ESSSECTI0NAND0XYGENIS0TOPESTAGESIntheYuanloessarea,manyscientiststhinkthatthesedimentsarecontinuousandtheclimaticrecordsareperfect.Thisdoesnotappeartobeaccurate.Sedimentationwasdiscontinuousinmanysections.Forexample,manyscientistsarguethatS2corresp0ndstooxygenisot0peStage7(Liu,l985,KuklaandAn,l989;Dingetal.,l990).lnfact,S2includesthreelayersfS2SSl,S2LLlandS2SS2.Dingetal.(l990)reportedthatthereisathickunitofloessbetweenS2SSlandS2SS2intheBaicao…     

澄江生物群中的卵形川滇虫

近年来在云南昆明附近的海口镇和大板桥地区发现大量的节肢动物卵形川滇虫化石，这些化石隶属于澄江生物群，其所处的地层是下寒武统玉案山组。卵形川滇虫化石的不断发掘使得对该属种化石的研究和认识能在很大程度上取得新的进展。文章基于相当数量化石的信息统计，首先对化石保存的多种方式进行总结并分析其埋藏时的环境条件，其次分析卵形川滇虫一些有趣的生活习性并初步划分卵形川滇虫生长中历经3次蜕皮的发育阶段；对雌雄性个体特征（包括外部形态和内部器官的解剖）进行对照性描述。文中揭示卵形川滇虫的生活环境及运动方式，并将卵形川滇虫与中寒武世瓦普塔虾进行较为详尽的比较，列举两者不可归为一属的可靠证据。     

安徽石台下、中奥陶统紫台组的牙形刺

下、中奥陶统紫台组以紫红色泥质灰岩、瘤状泥质灰岩为特征,具有稳定的空间分布范围,沿扬子台地东南缘呈条带状分布,与扬子台地上发育的湄潭组、大湾组等大致同期。作者研究了安徽石台栗阳柳树亭剖面紫台组的牙形刺,共描述19属23种,识别出四个牙形刺带,从下至上分别是Oepikodus evae带、Baltoniodus triangularis带、Baltoniodus navis带和Paroistodus originalis带,并可与同期笔石带对比。除扬子区外,紫台组还可与欧洲、阿根廷前科迪勒拉等地区的同期地层对比。     

Revision ofSemionotus bergeri Agassiz, 1833 (Upper Triassic, Germany), with comments on the taxonomic status ofSemionotus (Actinopterygii, Semionotiformes).

Semionotus bergeri Agassiz, 1833, from the Upper Triassic (Carnian) of southern Germany, the type species ofSemionotus, is here described in detail for the first time, including so far unstudied material in the Naturkunde-Museum Coburg, which allows a fairly complète reconstruction of this fish. The species is diagnosed by the présence of long frontals, about 4 times longer than wide, with antorbital lateral processes, 6–7 posterior infraorbitals, infraorbital at the posteroventral corner of the orbit notably larger than adjacent ones, infraorbitals at the posterior border of the orbit being as deep as long, and the middle élément anteroventrally expanded, dorsal fin base about two times the anal fin base.S. elegans from the Late Triassic-Early Jurassic of the Newark Supergroup in North America, is so far the best know species ofSemionotus and is the only species of this genus that has been included in phylogentic analyses. However, the comparison ofS. bergeri with other proposed speciesof Semionotus, such asS. elegans, and other semionotids casts doubt on the monophyly of this genus as currently understood, since these species exhibit a mosaic distribution of characters.      

昆明地区下寒武统节肢动物Guangweicaris Luo,Fu et Hu,2007的再研究

昆明地区下寒武统沧浪铺组乌龙箐段所产的节肢动物Guangweicaris Luo,Fu et Hu,2007,为研究寒武纪生命大爆发之后节肢动物辐射特征提供了重要资料。罗惠麟等(2007)在报道该节肢动物时,因标本不完整,对其头部和尾部特征均作了错误鉴别和描述。笔者根据完整且保存有软体附肢的标本,对Guangweicaris Luo,Fu et Hu,2007作了重新研究和复原,据此讨论了该节肢动物的分类归属问题。     

Turonian Pinaceae of the Raritan Formation, New Jersey

 Fossil vegetative and reproductive structures from deposits of the Raritan Formation in New Jersey (Turonian, Upper Cretaceous, ∼90 MYBP) include ferns, gymnosperms, and angiosperms. Gymnosperms collected from this formation have been known since the beginning of the 20th century. Fossil leaves, wood and seed cones have been are identified as belonging to the Cupressaceae, Pinaceae, and Taxodiaceae. In the present contribution, we describe a series of fossil dwarf shoots, leaves and a pollen cone belonging to the family Pinaceae. Fossils are charcoalified with preserved three-dimensional structure and excellent cellular detail. The dwarf shoots are assigned to a new species Prepinus crossmanensis sp. nov. and to the previously described Pinus quinquefolia Jeffrey. The new species Prepinus crossmanensis differs in size, shape, presence of hypodermis, sclerenchyma and stomata in the cataphylls, and number and shape of needle leaves from previously known species. Also, isolated leaves were found that were assigned to the new species, Prepinus raritanensis sp. nov. The new species is differentiated by the size and shape of stomata, the presence of number of layers of the hypodermis; and the cell-shape and number of layers of the mesophyll and transfusion tissue. A previously undescribed male cone, Amboystrobus cretacicum gen. and sp. nov., has an axis with spirally attached microsporophylls, each bearing two abaxial ovoid microsporangia. The pollen grains are monosulcate and bisaccate (eusaccate), with an elliptical corpus, granulate exine sculpture, and honeycomb-like wall structure. Received March 21, 2000 Accepted November 13, 2000     

Palaeocommunity Dynamics and Behavioral Analysis of Conichnus: Bhuj Formation (Lower Cretaceous),Kachchh-India

A palaeocommunity of large Conichnus conicus, a conical, cone-in-cone shaped burrow, created by sea anemones, occurs in medium-grained, crossbedded, well-sorted sandstone in the middle part of the Cretaceous Guneri Member of the Bhuj Formation in India. The trace fossil Conichnus is considered to be a common element of the Skolithos ichnofacies and is interpreted to reflect equilibrium movement in response to substrate aggradation. In the present study, three different varieties of Conichnus conicus are distinguished based on morphology and internal fabric. Community dynamics and burrowing behavior are revealed by inter-burrow relationships, burrow initiation levels and sedimentology. Three types of behavior are envisaged: retrusive equilibrium, protrusive equilibrium response, and escape behavior. Palaeocommunity dynamics show that the tracemakers consisted of only adult organisms that initiated burrows during neap tides and are adapted to feed effectively during weak flow conditions. The occurrence of Conichnus palaeocommunity in the Guneri Member indicates the tidal conditions in a fully marine setting. Results presented herein may aid in the understanding of palaeocommunity dynamics in other shallow marine sequences.     

High evolutionary rates and the origin of the Rosso Ammonitico Veronese Formation (Middle-Upper Jurassic of Italy) reptiles

The fossil record of metriorhynchids and plesiosaurians from the Rosso Ammonitico Veronese Formation (RAVFm, Middle–Upper Jurassic, Italy) is represented by elements collected between the eighteenth and twentieth centuries. All the metriorhynchid material is referred to the genus Neptunidraco. The first RAVFm plesiosaurian material was collected in the nineteenth century and referred to Plesiosaurus: elements are here described and interpreted as a chimerical association of crocodylomorph and plesiosaurian bones, providing the first co-occurrence of these clades in the RAVFm. The second plesiosaurian is the associated skeleton that we refer to Anguanax zignoi gen. et sp. nov. Bayesian phylogenetic analysis confirms the basal geosaurine affinities of Neptunidraco resulted by parsimony analysis. Using both methods, Anguanax was recovered as a basal pliosaurid, sister group of the clade including Marmornectes and Thalassophonea. Bayesian inference methods indicate that both Italian lineages diverged from other known lineages between 176 and 171 Mya, also showing divergence rates significantly higher than any other representative of their respective clades. We suggest a phase of rapid evolutionary adaptation to deeper marine environments in the ancestors of the Rosso Ammonitico Veronese reptiles as a response to the latest Liassic regressive regime in Northern Tethys.     

湖北峡东地区九龙湾剖面震旦系陡山沱组微体化石的新发现

中国南方扬子地台震旦系陡山沱组产出丰富的微体化石，它们主要保存在磷块岩以及燧石结核和条带中。文章详细报道湖北峡东地区九龙湾剖面震旦系陡山沱组微体化石，描述以前未曾在峡东地区碳酸盐相燧石中发现的8属8种微体化石。研究九龙湾剖面陡山沱组大型带刺疑源类、微体多细胞藻类和动物胚胎化石的分布特征，发现Tianzhushania spinosa是最早出现的大型带刺疑源类分子，大冰期后微体生物的辐射是一个阶段性渐进的过程。同时．本项研究进一步证实华南扬子区陡山沱组碳酸盐相燧石和磷块岩地层中保存的微体化石面貌基本一致。