bluuebunny/crossref_metadata_2025_split huggingface dataset:
High‐Energy X‐ray Absorption Spectroscopy: A New Tool for Structural Investigations of Lanthanoids and Third‐Row Transition Elements
Authors: D'Angelo Paola , De Panfilis Simone , Filipponi Adriano , Persson Ingmar 
Published: February 2008

AbstractThis is the first systematic study exploring the potential of high‐energy EXAFS as a structural tool for lanthanoids and third‐row transition elements. The K‐edge X‐ray absorption spectra of the hydrated lanthanoid(III) ions both in aqueous solution and in solid trifluoromethanesulfonate salts have been studied. The K‐edges of lanthanoids cover the energy range from 38 (La) to 65 keV (Lu), while the corresponding energy range for the L3‐edges is 5.5 (La) to 9.2 keV (Lu). We show that the large widths of the core‐hole states do not appreciably reduce the potential structural information in the high‐energy K‐edge EXAFS data. Moreover, for lanthanoid compounds, more accurate structural parameters are obtained from analysis of K‐edge than from L3‐edge EXAFS data. The main reasons are the much wider k range available and the absence of double‐electron transitions, especially for the lighter lanthanoids. A comparative K‐ and L3‐edge EXAFS data analysis of nonahydrated crystalline neodymium(III) trifluoromethanesulfonate demonstrates the clear advantages of K‐edge analysis over conventionally performed studies at the L3‐absorption edge for structural investigations of lanthanoid and third‐row transition metal compounds. The coordination chemistry of the hydrated lanthanoid(III) ions in aqueous solution and solid trifluoromethanesulfonate salts, based on the results of both the K‐ and L3‐edge EXAFS data, is thoroughly discussed in the next paper in this series (I. Persson, P. D'Angelo, S. De Panfilis, M. Sandström, L. Eriksson, Chem. Eur. J. 2008, 14, DOI: 10.1002/chem.200701281).
Topological Classification and Supramolecular Chirality of 21‐Helical Ladder‐Type Hydrogen‐Bond Networks Composed of Primary Ammonium Carboxylates: Bundle Control in 21‐Helical Assemblies
Authors: Yuge Tetsuharu , Sakai Tatsuya , Kai Nobuyasu , Hisaki Ichiro , Miyata Mikiji , Tohnai Norimitsu 
Published: February 2008

AbstractThe supramolecular chirality of 1D ladder‐type hydrogen‐bond networks composed of primary ammonium carboxylates was determined based on topological considerations. Chirality in such networks is based on the absolute configuration of the primary ammonium cation, which arises from discrimination between the two oxygen atoms of the carboxylate anion. The configurations of the cations and anions generate topological diversity in the networks, which are classified into six subgroups. In the Cambridge Structural Database, salts based on ladder type 1 constitute over 70 % of salts with a 1D‐ladder‐type network. Ladder type 1, based on a 21‐axis, is not superimposable on its mirror image, which leads to the first definition of right‐ or left‐handedness of 21‐helicity on the basis of supramolecular tilt chirality. Helical assemblies of 21‐type with triaxial chirality can be assembled in various ways to yield chiral bundles and crystals. On the basis of these considerations, we constructed clay mimic structures with several bundle patterns by connecting the hydrogen‐bond networks by using bifunctional molecules. These results open up the possibility of in‐depth crystal engineering based on hydrogen‐bond topology.
On the origin of circular dichroism in trigonal dihedral d6 complexes of bidentate ligands containing only σ‐orbitals. A qualitative model based on a density functional theory study of Λ‐[Co(en)3]3+
Authors: Fan Jing , Ziegler Tom 
Published: February 2008

AbstractTime‐dependent density functional theory (TD‐DFT) in conjunction with qualitative molecular orbital theory is employed to interpret the circular dichroism (CD) spectrum of Λ‐[Co(en)3]3+. The simulated spectrum based on TD‐DFT is compared in details with the experimental data. Emphasis is put on a qualitative understanding of the origin of optical activity in σ‐bonded trigonal dihedral complexes with bidentate ligands in general. Rotatory strengths associated with the CD bands of both d‐d transitions and ligand‐to‐metal charge transfer (LMCT) are interpreted based on the metal–ligand σ‐interactions. These interactions are in turn analyzed in terms of symmetry unique overlaps between metal d‐ and symmetry ligand‐orbitals as well as the dependence of these overlaps on geometrical parameters of the complex. Chirality, 2008. © 2008 Wiley‐Liss, Inc.
Circular dichroism of polynucleotides: Interactions of NiCl2 with poly(dA‐dT)·poly(dA‐dT) and poly(dG‐dC)·poly(dG‐dC) in a water‐in‐oil microemulsion
Authors: Airoldi Marta , Gennaro Giuseppe , Giomini Marcello , Giuliani Anna Maria , Giustini Mauro 
Published: February 2008

AbstractThe thermal behavior of the synthetic, high molecular weight, double stranded polynucleotides poly(dA‐dT)·poly(dA‐dT) [polyAT] and poly(dG‐dC)·poly(dG‐dC) [polyGC] solubilized in the aqueous core of the quaternary water‐in‐oil cationic microemulsion CTAB|n‐pentanol|n‐hexane|water in the presence of increasing amounts of NiCl2 at several constant ionic strength values (NaCl) has been studied by means of circular dichroism and electronic absorption spectroscopies. In the microemulsive medium, both polynucleotides show temperature‐induced modifications that markedly vary with both Ni(II) concentration and ionic strength. An increase of temperature causes denaturation of the polyAT duplex at low nickel concentrations, while more complex CD spectral modifications are observed at higher nickel concentrations and ionic strengths. By contrast, thermal denaturation is never observed for polyGC. At low Ni(II) concentrations, the increase of temperature induces conformational transitions from B‐DNA to Z‐DNA form, or, more precisely, to left‐handed helical structures. In some cases, at higher nickel concentrations, the CD spectra suggest the presence of Z′‐type forms of the polynucleotide. Chirality, 2008. © 2008 Wiley‐Liss, Inc.
Neck treatment of patients with early stage oral tongue cancer
Authors: Huang Shiang‐Fu , Kang Chung‐Jan , Lin Chen‐Yu , Fan Kang‐Hsing , Yen Tzu‐Chen , Wang Hung‐Ming , Chen I‐How , Liao Chun‐Ta , Cheng Ann‐Joy , Chang Joseph Tung‐Chieh 
Published: February 2008

AbstractBACKGROUND.The role of elective and therapeutic selective neck dissection in patients with early stage cancer of the oral tongue remains controversial. The purpose was to investigate the role of neck treatment in the management of this condition.METHODS.A total of 380 patients with cT1‐2N0 oral tongue cancer were retrospectively reviewed. Patients were staged by means of computed tomography (CT) or magnetic resonance imaging (MRI) scans. A total of 324 patients received elective neck dissection (END), whereas 56 participants received observation (OBS). In all, 287 patients received supraomohyoid neck dissection (SOND), whereas 37 patients received modified radical neck dissection (MRND). Overall survival (OS) and neck control rates (NCR) were investigated according to the treatment modality.RESULTS.In the END group the occult metastasis (OM) rates in cervical lymph nodes were 5.2% for cT1 lesions and 14.6% for cT2 lesion (P = .005). The 5‐year OS (P = .029) and NCR rates (P = .001) were significantly better in the END group compared with the OBS group. Patients who received MRND had a better 5‐year NCR compared with SOND, albeit not significantly (91.4% vs 85.3%, P = .415). Multivariate analysis showed that END and stage were independent predictors of both NCR and OS.CONCLUSIONS.END should be performed routinely in patients with early‐stage oral tongue cancer, even in the presence of negative neck by CT scans and MRI. Cancer 2008. © 2008 American Cancer Society
Neuronal expression and subcellular localization of cholesterol 24‐hydroxylase in the mouse brain
Authors: Ramirez Denise M.O. , Andersson Stefan , Russell David W. 
Published: February 2008

AbstractCholesterol 24‐hydroxylase is a cytochrome P450 (CYP46A1) that is selectively expressed in the brain and is responsible for the majority of cholesterol turnover in the central nervous system. Mice deficient in 24‐hydroxylase exhibit impaired learning and defective hippocampal long‐term potentiation, suggesting that the metabolism of cholesterol by this enzyme is required for learning and memory formation. To determine where in the neuron cholesterol turnover was taking place, monoclonal antibodies directed against 24‐hydroxylase were generated by immunization of mice with recombinant protein and used to detect the enzyme in brain homogenates, cultured neurons, and histological sections. 24‐Hydroxylase was localized to the endoplasmic reticulum and was distributed throughout the cell bodies and dendrites of multiple types of neurons; the enzyme was not detected in axon terminals or in the cells of 24‐hydroxylase knockout mice. 24‐Hydroxylase was highly expressed in pyramidal neurons of the hippocampus and cortex, in Purkinje cells of the cerebellum, and in hippocampal and cerebellar interneurons. Within the retina, 24‐hydroxylase was detected in ganglion cells and some but not all cells of the inner nuclear layer. These findings reveal the microsomal localization of 24‐hydroxylase and provide subcellular insight into cholesterol turnover in the brain. J. Comp. Neurol. 507:1676–1693, 2008. © 2008 Wiley‐Liss, Inc.
Developmental origins of species differences in telencephalon and tectum size: Morphometric comparisons between a parakeet (Melopsittacus undulatus) and a quail (Colinus virgianus)
Authors: Striedter Georg F. , Charvet Christine J. 
Published: February 2008

AbstractParrots, including parakeets, evolved significantly larger brains than other birds, relative to their body size, and they possess a proportionately larger telencephalon. For example, the telencephalon occupies approximately 68% of the brain in parakeets but only 52% in bobwhite quail. The present study was designed to determine when and how this difference in brain region proportions arises during development. To that end, we present volumetric data on the major brain regions in parakeets and bobwhite quail at several stages of embryogenesis, at hatching and, for the parakeets, 1 week after hatching. We also report on the proportional sizes of each region's proliferative and postproliferative zones. One major finding is that parakeets develop a proportionately larger telencephalon relatively late in development and that this late increase correlates with a delay in telencephalic neurogenesis. The most prominent aspect of this delayed telencephalic development is a tremendous expansion of the proliferative subventricular zone in the telencephalon of late embryonic and posthatching parakeets. The second major finding is that the tectum is much smaller in parakeets than in quail at all developmental stages examined, suggesting that the tectum's reduced size is due to an evolutionary change in how much tissue was allocated to become tectum at the time of brain regionalization. Collectively these findings indicate that evolutionary changes in brain region proportions are caused not by a single type of change but by several distinct developmental mechanisms, including changes in brain regionalization and neurogenesis timing. J. Comp. Neurol. 507:1663–1675, 2008. © 2008 Wiley‐Liss, Inc.
Crystallization of vitamin C in a continuous DT MSMPR crystallizer – Size independent growth kinetic model approach
Authors: Wierzbowska B. , Piotrowski K. , Koralewska J. , Matynia A. , Hutnik N. , Wawrzyniecki K. 
Published: February 2008

AbstractThe experimental results concerning continuous mass crystallization process in L(+)‐ascorbic acid – water system are presented and discussed. Influence of L(+)‐ascorbic acid concentration in a feeding solution and mean residence time of suspension in laboratory DT MSMPR crystallizer on product crystal size distribution as well as nucleation and growth kinetics were determined. Kinetic parameter values were evaluated on the basis of size–independent growth (SIG) kinetic model (McCabe's ΔL law). It was observed, that within the examined range of crystallizer productivity (120–1600 kg LAA crystals m–3h–1) crystal product population of mean size Lm from 0.2 to 0.3 mm and CV from 66.6 to 49% is withdrawn. Linear growth rate values present decreasing trend (from ca. 7 · 10–8 to ca. 6 · 10–8 m s–1) with the productivity increase (assuming constant mean residence time of suspension τ = 900 s). Occurrence of secondary nucleation within the circulated and mixed suspension, resulting from crystal attrition and breakage, was observed. The parameter values in design equation connecting linear growth rate and suspension density with nucleation rate were determined. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Creation of calcite hollow microspheres with attached bundles of aragonite needles
Authors: Tang Hua , Yu Jiaguo , Zhao Xiufeng , Ng Dickon H. L. 
Published: February 2008

AbstractNovel calcite hollow microspheres attached with bundles of aragonite needles have been synthesized via a simple precipitation reaction of aqueous solutions of CaClB2B and NaB2BCOB3B in the presence of MgP2+P ions at room temperature. The experimental results revealed that an appropriate molar ratio of [MgP2+P]/[CaP2+P], pH value of the solution and aging time are crucial for the formation of the unusual hierarchical CaCOB3B superstructure. A possible growth mechanism is proposed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis and crystallographic characterization of a seven‐coordinate Mn(II) complex
Authors: Chen Huating , Deng Dongsheng , Miao Shaobin , Ji Baoming 
Published: February 2008

AbstractA seven‐coordinate Mn(II) complex of N,N,N ′,N ′‐tetrakis[(2‐benzimidazolyl)methyl]‐1,2‐cyclohexanediamine (CDTB), namely, [Mn(CDTB)(DMF)](Pic)2·C2H5OH was synthesized and characterized by elemental analyses, IR spectra and X‐ray single‐crystal diffraction. The complex crystallizes in a typical hybrid organic‐inorganic pattern. The crystal belongs to the monoclinic system, space group P 2 (1) / n with cell constants a = 13.3343(6) Å, b = 33.7015(16) Å, c = 13.7286(6) Å, β = 108.9990(10)°, Z = 4. The structure was solved by direct methods and refined to R = 0.0561 (wR2 = 0.1172). The structure analysis reveals that the Mn(II) has a capped octahedron geometry with seven‐coordination mode, furthermore, the [Mn(CDTB)(DMF)]2+ building blocks were extended into well‐ordered supramolecular networks by complementary hydrogen bonds, and the linkers of the ethanol molecules and the picrate anions play an important role in the self‐assembly process. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth, spectral and thermal properties of KAP single crystals in the presence of DL‐Alanine and L‐Methionine amino acid dopants
Authors: Uthayarani K. , Sankar R. , Shashidharan Nair C. K. 
Published: February 2008

AbstractSingle crystals of potassium acid phthalate (KAP) and amino acid (DL‐Alanine, L‐Methionine) doped KAP were grown from aqueous solutions by slow cooling method. The grown crystals were characterized using powder X Ray diffraction (XRD) and Fourier Transform Infrared (FTIR) analysis. The thermal stability of KAP in the presence of dopants was analysed using Thermogravimetric and Differential Scanning caloriemetric (TGA/ DSC) studies and the maximum temperature for non linear optical application of this compound in the presence of dopants was found out. The transmittance of KAP was found to increase in the presence of dopants. Etch pits were observed for all the crystals using different etchants. Vickers microhardness tests were performed to study the mechanical stability of the crystals. The hardness of DL‐alanine doped KAP is more than that of L‐alanine doped KAP crystal. The dielectric constant and loss were determined as a function of temperature. Frequency response of the dielectric constant and dielectric loss factor have been studied over the frequency range of 50Hz – 5MHz. Second harmonic generation (SHG) was confirmed in all the crystals using the Kurtz and Perry powder technique. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Neue Regelungen für Kupplungen zur Verwendung an Stahl‐ und Aluminiumrohren
Authors: Schult Andreas 
Published: February 2008

AbstractKupplungen sind Gerüstbauteile, die wiederholt in temporären Konstruktionen verwendet werden. Die Erfahrungen haben gezeigt, dass diese Gerüstbauteile bei entsprechender Behandlung und Wartung durchaus eine Lebensdauer von 30 Jahren oder auch mehr aufweisen können. Voraussetzung hierbei ist, dass zum Zeitpunkt der Verwendung eine gültige technische Regel für die Verwendung vorliegt. Diese Forderung hat zur Folge, dass jede Änderung der technischen Regel im Laufe der Zeit zu der Frage führt, wie mit vorhandenen Beständen an Gerüstbauteilen zu verfahren ist.
Inverkehrbringen und Verwendung von Bauprodukten – die Bauproduktenrichtlinie und ihre Umsetzung
Authors: Springborn Matthias 
Published: February 2008

AbstractEnde 1988 ist die Bauproduktenrichtlinie erlassen worden. Damit nahm man sich auf europäischer Ebene eines Binnenmarktsektors an, der eine herausragende Bedeutung für Europa hat. Mit 11,8 Millionen direkt Beschäftigter ist das Baugewerbe der größte Arbeitgeber im europäischen produzierenden Gewerbe, auf den in der Europäischen Union der 15 “alten” Mitgliedstaaten 7 % der Gesamtbeschäftigung und 28 % der Beschäftigung im produzierenden Gewerbe entfallen. Man schätzt, dass in der EU der 15 etwa 26 Millionen Arbeitskräfte in irgendeiner Weise vom Baugewerbe abhängig sind. Die Bauinvestitionen beliefen sich 2003 auf rund 910 Milliarden 3, das waren 10 % des Bruttoinlandsproduktes und 51,2 % der Bruttoanlageinvestitionen von EU‐15.Es handelt sich aber ebenso um einen Sektor, der besondere Schwierigkeiten bei der europäischen Harmonisierung mit sich bringt und Probleme aufwirft, für deren Lösung es bisher keine Präzedenzfälle gibt. Warum das so ist, das soll im folgenden Beitrag deutlich werden.
Leitlinie für europäische technische Zulassungen “Abdichtungen für Böden und Wände in Nassräumen” (ETAG 022) Teil 1 im Bundesanzeiger bekannt gemacht
Authors: Herold Christian , Mehring Adolf 
Published: February 2008

AbstractDie von der EOTA (European Organisation for Technical Approvals) erarbeitete Leitlinie für europäische technische Zulassungen für “Abdichtungen für Böden und Wände in Nassräumen” (ETAG 022) bildet die Grundlage für die technische Beurteilung der Brauchbarkeit von Bausätzen für Abdichtungen in Nassräumen, die zur Erteilung einer europäischen technischen Zulassung (ETA) führt.Die Leitlinie gliedert sich in drei Teile:Teil 1: Flüssig aufzubringende Abdichtungen mit oder ohne NutzschichtTeil 2: AbdichtungsbahnenTeil 3: Wasserdichte PlattenDer Teil 1 dieser Leitlinie ist von der Europäischen Kommission angenommen und den Mitgliedstaaten am 18. Juli 2007 zur Veröffentlichung in den jeweiligen Amtssprachen empfohlen worden. Die deutsche Sprachfassung wurde am 31. Oktober 2007 im Bundesanzeiger bekannt gemacht. Auf dieser Grundlage können ab sofort europäische technische Zulassungen (ETAs) erteilt werden. In Deutschland ist die hierfür zuständige Stelle das Deutsche Institut für Bautechnik (DIBt). Anträge sind auf den dafür vorgesehenen Formblättern zu stellen.
Metalloid Cluster Compounds of Germanium: Synthesis – Properties – Subsequent Reactions
Authors: Schnepf Andreas 
Published: February 2008

AbstractMetalloid cluster compounds represent ideal model compounds that provide an insight into the area between the molecular and the solid state. This borderland is of particular interest especially for metals or semimetals, as a drastic change of the physical properties takes place from the oxidized species (salt, nonconducting) to the bulk phase (metal, semimetal, conducting, semiconducting). For the heavier group 14 elements, this area is also of great technical interest as the module size in the computer industry approaches the nanometre range. This review describes recent achievements in the synthesis of metalloid cluster compounds of germanium. Besides different ligand systems used in synthesis, first examples of subsequent reactions of such cluster compounds are presented and further applications are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Structural Diversity in Organotin Compounds Derived from Bulky Monoaryl Phosphates: Dimeric, Tetrameric, and Polymeric Tin Phosphate Complexes
Authors: Murugavel Ramaswamy , Shanmugan Swaminathan , Kuppuswamy Subramaniam 
Published: February 2008

AbstractMonoaryl phosphates with a bulky aryl substituent have been used to synthesize new organotin clusters and polymers. The equimolar reaction between 2,6‐diisopropylphenylphosphate (dipp‐H2) and Me2SnCl2 in ethanol at 25 °C leads to the formation of [Me2Sn(μ3‐dipp)]n (1), while the reaction of 2,6‐dimethylphenylphosphate (dmpp‐H2) with Me2SnCl2 in either a 1:1 or 2:1 molar ratio proceeds to produce exclusively [Me2Sn(μ‐dmpp‐H)2]n·nH2O (2). Compounds 1 and 2 are 1D polymers with different architectures. In compound 1, the tin atom is five‐coordinate (trigonal bipyramidal). Each dipp ligand bridges three different tin atoms to form an infinite ladder‐chain structure. In 2, each six‐coordinate (octahedral) tin atom is surrounded by four phosphate oxygen atoms originating from four different bridging dmpp‐H ligands, thus forming a spirocyclic coordination polymeric chain. The use of nBu2SnO as the diorganotin source in its reaction with dipp‐H2 leads to the isolation of dimeric [nBu2Sn(μ‐dipp‐H)(dipp‐H)]2 (4), which contains a central Sn2O4P2 unit. There are two chemically different half molecules of 4 in the asymmetric part of the unit cell and hence it actually exists as a 1:1 mixture of [nBu2Sn(μ‐dipp‐H)(dipp‐H)]2 and [nBu2Sn(μ‐dipp)(dipp‐H2)]2 in the solid state. The reaction of the monoorgano tin precursor nBuSn(O)(OH)·xH2O with dipp‐H2 takes place in acetone at room temperature to yield the tetrameric cluster 5, which has different structures in the solution and in the solid state. 31P NMR spectroscopy clearly suggests that 5 has the formula [nBu4Sn4(μ‐O)2(μ‐dipp‐H)8] in solution. The single‐crystal X‐ray diffraction studies in the solid state, however, reveal that compound 5 exists as [nBu4Sn4(μ‐OH)2(μ‐dipp‐H)6(μ‐dipp)2]. The use of compounds 1–4 as possible precursors for the preparation of ceramic tin phosphate materials has been investigated. The thermolysis of 1 at 500 °C leads to the formation of quantitative amounts of Sn2P2O7, while the thermolysis of 2, 3, and 4 under similar conditions results in the formation of SnP2O7. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis of Novel Bis(β‐lactam)‐1,3‐diynes by Copper‐Promoted Homo‐ or Cross‐Coupling of Alkynyl‐2‐azetidinones
Authors: Alcaide Benito , Almendros Pedro , Carrascosa Rocío , Rodríguez‐Acebes Raquel 
Published: February 2008

AbstractCu(OAc)2in combination with K2CO3(a solid base instead of an amine) was proven to be an extremely effective system for promoting the homocoupling of various (β‐lactam)acetylenes to affordC2‐symmetrical bis(β‐lactam)‐1,3‐diynes, whereas these 2‐azetidinone‐tethered alkynes underwent the Cadiot–Chodkiewicz cross‐coupling reaction with different 2‐azetidinone bromoalkynes to form a variety of unsymmetrical bis(β‐lactam)diynes in good yields. In addition to their potential biological activity, the resulting enantiopure bis(β‐lactam)‐1,3‐diynes can be converted into bis(β‐amino ester)‐1,3‐diynes, which may find use as macrocyclic cavities, as well as chiral ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)