bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maternal occupational exposure to polycyclic aromatic hydrocarbons and congenital heart defects among offspring in the national birth defects prevention study
Authors: Lupo Philip J. , Symanski Elaine , Langlois Peter H. , Lawson Christina C. , Malik Sadia , Gilboa Suzanne M. , Lee Laura J. , Agopian A. J. , Desrosiers Tania A. , Waters Martha A. , Romitti Paul A. , Correa Adolfo , Shaw Gary M. , Mitchell, Laura E. ,   and the National Birth Defects Prevention Study
Published: September 2012

AbstractBACKGROUND:There is evidence in experimental model systems that exposure to polycyclic aromatic hydrocarbons (PAHs) results in congenital heart defects (CHDs); however, to our knowledge, this relationship has not been examined in humans. Therefore, we conducted a case‐control study assessing the association between estimated maternal occupational exposure to PAHs and CHDs in offspring. METHODS:Data on CHD cases and control infants were obtained from the National Birth Defects Prevention Study for the period of 1997 to 2002. Exposure to PAHs was assigned by industrial hygienist consensus, based on self‐reported maternal occupational histories from 1 month before conception through the third month of pregnancy. Logistic regression was used to evaluate the association between maternal occupational PAH exposure and specific CHD phenotypic subtypes among offspring. RESULTS:The prevalence of occupational PAH exposure was 4.0% in CHD case mothers (76/1907) and 3.6% in control mothers (104/2853). After adjusting for maternal age, race or ethnicity, education, smoking, folic acid supplementation, and study center, exposure was not associated with conotruncal defects (adjusted odds ratio [AOR], 0.98; 95% confidence interval [CI], 0.58–1.67), septal defects (AOR, 1.28; 95% CI, 0.86–1.90), or with any isolated CHD subtype. CONCLUSIONS:Our findings do not support an association between potential maternal occupational exposure to PAHs and various CHDs in a large, population‐based study. For CHD phenotypic subtypes in which modest nonsignificant associations were observed, future investigations could be improved by studying populations with a higher prevalence of PAH exposure and by incorporating information on maternal and fetal genotypes related to PAH metabolism. Birth Defects Research (Part A), 2012. © 2012 Wiley Periodicals, Inc.
Epithelial fusion during neural tube morphogenesis
Authors: Pai Yun‐Jin , Abdullah N.L. , Mohd.‐Zin S.W. , Mohammed R.S. , Rolo Ana , Greene Nicholas D.E. , Abdul‐Aziz Noraishah M. , Copp Andrew J. 
Published: September 2012

AbstractAdhesion and fusion of epithelial sheets marks the completion of many morphogenetic events during embryogenesis. Neural tube closure involves an epithelial fusion sequence in which the apposing neural folds adhere initially via cellular protrusions, proceed to a more stable union, and subsequently undergo remodeling of the epithelial structures to yield a separate neural tube roof plate and overlying nonneural ectoderm. Cellular protrusions comprise lamellipodia and filopodia, and studies in several different systems emphasize the critical role of RhoGTPases in their regulation. How epithelia establish initial adhesion is poorly understood but, in neurulation, may involve interactions between EphA receptors and their ephrinA ligands. Epithelial remodeling is spatially and temporally correlated with apoptosis in the dorsal neural tube midline, but experimental inhibition of this cell death does not prevent fusion and remodeling. A variety of molecular signaling systems have been implicated in the late events of morphogenesis, but genetic redundancy, for example among the integrins and laminins, makes identification of the critical players challenging. An improved understanding of epithelial fusion can provide insights into normal developmental processes and may also indicate the mode of origin of clinically important birth defects. Birth Defects Research (Part A), 2012. © 2012 Wiley Periodicals, Inc.
Bemessung und Konstruktion von zweiachsig gespannten Stahlbetondecken mit abgeflachten rotationssymmetrischen Hohlkörpern
Authors: Albrecht Christian , Albert Andrej , Pfeffer Karsten , Schnell Jürgen 
Published: September 2012

AbstractZur Realisierung von leichten, zweiachsig gespannten Decken werden Hohlkörpersysteme vermehrt eingesetzt, was zu einer wirtschaftlichen und ressourcenschonenden Bauweise führt. Bei der Bemessung und Konstruktion muss das besondere Tragverhalten dieser Systeme berücksichtigt werden. Es werden experimentelle Untersuchungen notwendig, um ein abgesichertes Bemessungsmodell aufstellen zu können. Mittels numerischer Untersuchungen können die Versuche nachgerechnet und Parameterstudien durchgeführt werden. Vereinfachungen und Bemessungshilfen ermöglichen den Tragwerksplanern eine einfache Bemessung und Konstruktion analog der massiven Flachdecke. Bei Berücksichtigung der Bemessungs‐ und Konstruktionsregeln können zweiachsig gespannte Stahlbetondecken mit abgeflachten rotationssymmetrischen Hohlkörpern auf dem bauaufsichtlich geforderten Sicherheitsniveau hergestellt werden.Design and construction of two‐way spanning reinforced concrete slabs with flattened rotationally symmetrical void formersFor the realization of lightweight, two‐way spanning concrete slabs, hollow body systems are increasingly used, resulting in economic and resource‐efficient constructions. In the design and construction, the special structural behavior of these systems must be considered. In order to establish a safe design model, experimental investigations are required. By numerical investigations, the tests can be modeled and parametric studies can be carried out. Simplifications and design tools allow a simple design and construction similar to the conventional reinforced concrete slabs. By considering the design and detailing rules of two‐way spanning concrete slabs with flattened rotationally symmetrical void formers, the safety level required by the building authority is met.
Tiefgaragen mit unbeschichteten Stahlbeton‐Bodenplatten – ein Erfahrungsbericht
Authors: Dauberschmidt Christoph , Vestner Stephan , von Thermann Edmund 
Published: September 2012

AbstractDie Ausführung von unbeschichteten, direkt befahrenen Bodenplatten ist eine nach den aktuellen Normen und Merkblättern anerkannte Bauweise, wenn zum einen ein möglichst chloriddichter Beton bei ausreichend hoher Betondeckung verwendet wird. Zum anderen sollten Maßnahmen ergriffen werden, um die Rissbildung zu vermeiden bzw. sollte eine “begleitende Rissbehandlung” im Rahmen der Wartung durchgeführt werden. Die Erfahrungen an insgesamt vier durch einen Fachplaner gutachterlich begleiteten Bauvorhaben zeigen, dass sowohl die Chloriddichtheit nachweisbar erreicht werden kann, als auch eine weitestgehende Rissfreiheit, selbst nach mehreren Wintern, eingehalten ist. Entscheidend für den Erfolg der rissfreien Konstruktion ist, dass bereits in den frühen Planungsphasen eine zwängungsarme Auflagerung berücksichtigt wird. Zudem sind auch ein ausreichendes Gefälle sowie die Konzeption von Entwässerungseinrichtungen frühzeitig planerisch zu berücksichtigen. Die Ausführungsqualität der Bodenplatte kann mittels zerstörungsfreier Betondeckungsmessungen und durch Bestimmung der Chloridbelastung überprüft werden. Letztlich konnte mit den hier beschriebenen, unbeschichteten Tiefgaragen‐Bodenplatten eine dauerhafte und wirtschaftliche Konstruktion gefunden werden, deren Instandhaltungsaufwand im Vergleich zu beschichteten Bodenplatten deutlich geringer sein wird.Uncoated and directly driven RC‐ground slabs in underground car parks – a field reportThe construction of an uncoated and directly driven RC‐ground slab is proven and acknowledged by standards and bulletins, if on one hand a concrete is used, which is chloride dense as possible in combination with a sufficient thick concrete cover. On the other hand actions should be taken to avoid crack initiation or an accompanied crack treatment within the scope of the maintenance should be carried out. The experience of four building projects, which were supervised by concrete technology consultants, show, that as well the chloride impermeability is verifiable achievable as hardly any cracks have been determined – even after several winter periods. Important to achieve a crack‐free construction is the consideration of a bearing with reduced restraints already in early stages of the design. Also the planning of a sufficient gradient of the surface and a drainage concept has to be considered early within design. The quality of the execution of the ground slab can be checked by using non destructive concrete cover measurement and by determining the chloride contamination. Finally a durable and cost‐effective construction could be achieved with the described uncoated subterranean garage ground slabs leading to a reduced maintenance expense compared to coated ground slabs.
H2O2‐ and pH‐sensitive CdTe quantum dots as fluorescence probes for the detection of glucose
Authors: Li Yinping , Li Baoxin , Zhang Junli 
Published: September 2012

ABSTRACTA novel fluorescence assay system for glucose was developed with thioglycollic acid (TGA)‐capped CdTe quantum dots (QDs) as probes. The luminescence quantum yield of the TGA‐capped CdTe QDs was highly sensitive to H2O2 and pH. In the presence of glucose oxidase, glucose is oxidized to yield, gluconic acid and H2O2. H2O2 and H+ (dissociated from gluconic acid) intensively quenched the fluorescence of QDs. The experimental results showed that the quenched fluorescence was proportional to the glucose concentration within the range of 0.01–5.0 mm under optimized experimental conditions. Compared with most of the existing methods, this newly developed system possesses many advantages, including simplicity, low cost, high flexibility, and good sensitivity. Furthermore, no complicated chemical modification of QDs and enzyme immobilization was needed in this system. Copyright © 2012 John Wiley & Sons, Ltd.
Dark‐red‐emitting CdTe/Cd1‐xZnxS core/shell quantum dots: preparation and properties
Authors: Yang Ping , Murase Norio 
Published: September 2012

ABSTRACTCdTe nanocrystals (NCs) were fabricated through an organic synthesis. The growth and properties of CdTe NCs depended strongly on the preparation conditions. In a reaction system of octadecene and tetradecylphosphonic acid (TDPA), the growth was slow. CdTe NCs with cubic‐like morphology were created in trioctylamine (TOA) using octadecylphosphonic acid (ODPA)‐CdO or TDPA‐CdO as precursors. The TOA and ODPA system gives rise to NCs with high photoluminescence (PL) efficiencies (12%). A CdxZn1‐xS shell coating on the CdTe core, gave rise to tunable dark red PL (630–670 nm). The morphology and PL properties of the CdTe cores were drastically affected by shell coating and this determined the properties of CdTe/CdxZn1‐xS NCs. Small CdTe NCs were easily coated with CdxZn1‐xS shells. The resulting core/shell NCs revealed a spherical morphology. However, shell growth became slow when large CdTe cores were used. This is ascribed to the cores with a cubic‐like morphology. CdS interlayer plays an important role for the formation of the CdTe/CdxZn1‐xS NCs because the experimental result indicated it is difficult to coat CdTe NCs with a ZnS shell. The core/shell NCs benefited from a CdxZn1‐xS composite shell because CdTe/CdS NCs created via a similar procedure revealed a low PL efficiency. Copyright © 2012 John Wiley & Sons, Ltd.
Genetic Encoding of a Bicyclo[6.1.0]nonyne‐Charged Amino Acid Enables Fast Cellular Protein Imaging by Metal‐Free Ligation
Authors: Borrmann Annika , Milles Sigrid , Plass Tilman , Dommerholt Jan , Verkade Jorge M. M. , Wießler Manfred , Schultz Carsten , van Hest Jan C. M. , van Delft Floris L. , Lemke Edward A. 
Published: September 2012

AbstractVisualizing biomolecules by fluorescent tagging is a powerful method for studying their behaviour and function inside cells. We prepared and genetically encoded an unnatural amino acid (UAA) that features a bicyclononyne moiety. This UAA offered exceptional reactivity in strain‐promoted azide–alkyne cycloadditions. Kinetic measurements revealed that the UAA reacted also remarkably fast in the inverse‐electron‐demand Diels–Alder cycloaddition with tetrazine‐conjugated dyes. Genetic encoding of the new UAA inside mammalian cells and its subsequent selective labeling at low dye concentrations demonstrate the usefulness of the new amino acid for future imaging studies.
Transition‐Metal Complexes of Tetrylones [(CO)5W‐E(PPh3)2] and Tetrylenes [(CO)5W‐NHE] (E=C–Pb): A Theoretical Study
Authors: Nguyen Thi Ai Nhung , Frenking Gernot 
Published: September 2012

AbstractQuantum chemical calculations at the BP86/TZVPP//BP86/SVP level are performed for the tetrylone complexes [W(CO)5‐E(PPh3)2] (W‐1 E) and the tetrylene complexes [W(CO)5‐NHE] (W‐2 E) with E=C–Pb. The bonding is analyzed using charge and energy decomposition methods. The carbone ligand C(PPh3) is bonded head‐on to the metal in W‐1 C, but the tetrylone ligands E(PPh3)2 are bonded side‐on in the heavier homologues W‐1 Si to W‐1 Pb. The WE bond dissociation energies (BDEs) increase from the lighter to the heavier homologues (W‐1 C: De=25.1 kcal mol−1; W‐1 Pb: De=44.6 kcal mol−1). The W(CO)5←C(PPh3)2 donation in W‐1 C comes from the σ lone‐pair orbital of C(PPh3)2, whereas the W(CO)5←E(PPh3)2 donation in the side‐on bonded complexes with E=Si–Pb arises from the π lone‐pair orbital of E(PPh3)2 (the HOMO of the free ligand). The π‐HOMO energy level rises continuously for the heavier homologues, and the hybridization has greater p character, making the heavier tetrylones stronger donors than the lighter systems, because tetrylones have two lone‐pair orbitals available for donation. Energy decomposition analysis (EDA) in conjunction with natural orbital for chemical valence (NOCV) suggests that the WE BDE trend in W‐1 E comes from the increase in W(CO)5←E(PPh3)2 donation and from stronger electrostatic attraction, and that the E(PPh3)2 ligands are strong σ‐donors and weak π‐donors. The NHE ligands in the W‐2 E complexes are bonded end‐on for E=C, Si, and Ge, but side‐on for E=Sn and Pb. The WE BDE trend is opposite to that of the W‐1 E complexes. The NHE ligands are strong σ‐donors and weak π‐acceptors. The observed trend arises because the hybridization of the donor orbital at atom E in W‐2 E has much greater s character than that in W‐1 E, and even increases for heavier atoms, because the tetrylenes have only one lone‐pair orbital available for donation. In addition, the WE bonds of the heavier systems W‐2 E are strongly polarized toward atom E, so the electrostatic attraction with the tungsten atom is weak. The BDEs calculated for the WE bonds in W‐1 E, W‐2 E and the less bulky tetrylone complexes [W(CO)5‐E(PH3)2] (W‐3 E) show that the effect of bulky ligands may obscure the intrinsic WE bond strength.
Cyclometalated Iridium(III)–Polyamine Complexes with Intense and Long‐Lived Multicolor Phosphorescence: Synthesis, Crystal Structure, Photophysical Behavior, Cellular Uptake, and Transfection Properties
Authors: Li Steve Po‐Yam , Tang Tommy Siu‐Ming , Yiu Ken Shek‐Man , Lo Kenneth Kam‐Wing 
Published: September 2012

AbstractA new class of phosphorescent cyclometalated iridium(III)–polyamine complexes [{Ir(N^C)2}n(bPEI)](PF6)n (bPEI=branched poly(ethyleneimine), average Mw=25 kDa, n=15.6–27.4; HN^C=2‐phenylpyridine Hppy (1 a), 2‐((1,1′‐biphenyl)‐4‐yl)pyridine Hpppy (2 a), 2‐phenylquinoline Hpq (3 a), 2‐phenylbenzothiazole Hbt (4 a), 2‐(1‐naphthyl)benzothiazole Hbsn (5 a)) and [Ir(N^C)2(en)](PF6) (en=ethylenediamine; HN^C=Hppy (1 b), Hpppy (2 b), Hpq (3 b), Hbt (4 b), Hbsn (5 b)) have been synthesized and characterized. The X‐ray crystal structure of complex 5 b was also determined. All of these complexes showed a reversible iridium(IV/III) oxidation couple at +1.01 to +1.26 V and a quasi‐reversible ligand‐based reduction couple at −1.54 to −2.08 V (versus SCE). Upon photoexcitation, the complexes displayed intense and long‐lived green to orange–red emission in fluid solutions at room temperature and in low‐temperature glass. Lipophilicity measurements indicated that bPEI played a dominant role in the polar nature of complexes 1 a–5 a, thus rendering them very soluble in aqueous solutions. Inductively coupled plasma–mass spectrometry (ICP‐MS) and confocal laser scanning microscopy (CLSM) data indicated that an energy‐requiring process, such as endocytosis, was involved in the cellular uptake of all of the complexes. In addition, the cytotoxicity of the complexes toward human cervix epithelioid carcinoma (HeLa) and human embryonic kidney 293T (HEK293T) cell‐lines has been evaluated by the 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyltetrazolium bromide (MTT) assay. The DNA‐binding properties of complex 5 a have been investigated by gel‐retardation assays and the polyplexes that were formed from this complex with plasmid DNA (pDNA) were studied by zeta‐potential measurements and particle‐size estimation. Furthermore, complex 5 a was grafted with poly(ethylene glycol) (PEG, average Mw=2 kDa) to different extents, thereby yielding the phosphorescent copolymers PEG12.3‐g‐5 a, PEG25.4‐g‐5 a, and PEG62.1‐g‐5 a. Interestingly, these copolymers showed enhanced transfection activity, as revealed by in vitro transfection experiments with tissue‐culture‐based luciferase assays.
Hierarchical Supramolecular Spinning of Nanofibers in a Microfluidic Channel: Tuning Nanostructures at a Dynamic Interface
Authors: Numata Munenori , Takigami Yusuke , Takayama Momoko , Kozawa Tomohiro , Hirose Naoya 
Published: September 2012

AbstractOne of the fundamental problems in supramolecular chemistry, as well as in material sciences, is how to control the self‐assembly of polymers on the nanometer scale and how to spontaneously organize them towards the macroscopic scale. To overcome this problem, inspired by the self‐assembly systems in nature, which feature the dynamically controlled self‐assembly of biopolymers, we have previously proposed a self‐assembly system that uses a dynamic liquid/liquid interface with dimensions in the micrometer regime, thereby allowing polymers to self‐assemble under precisely controlled nonequilibrium conditions. Herein, we further extend this system to the creation of hierarchical self‐assembled architectures of polysaccharides. A natural polysaccharide, β‐1,3‐glucan (SPG), and water were injected into opposite “legs” of microfluidic devices that had a Y‐shape junction, so that two solvents would gradually mix in the down stem, thereby causing SPG to spontaneously self‐assemble along the flow in a head‐to‐tail fashion, mainly through hydrophobic interactions. In the initial stage, several SPG nanofibers would self‐assemble at the Y‐junction owing to the shearing force, thereby creating oligomers with a three‐way junction point. This unique structure, which could not be created through conventional mixing procedures, has a divergent self‐assembly capability. The dynamic flow allows the oligomers to interact continuously with SPG nanofibers that are fed into the Y‐junction, thus amplifying the nanostructure along the flow to form SPG networks. Consequently, we were able to create stable, centimeter‐length macroscopic polysaccharide strands under the selected flow conditions, which implies that SPG nanofibers were assembled hierarchically in a supramolecular fashion in the dynamic flow. Microscopic observations, including SEM and AFM analysis, revealed the existence of clear hierarchical structures inside the obtained strand. The network structures self‐assembled to form sub‐micrometer‐sized fibers. The long fibers further entangled with each other to give stable micrometer‐sized fibers, which finally assembled to form the macroscopic strands, in which the final stabilities in the macroscopic regime were governed by that of the network structures in the nanometer regime. Thus, we have exploited this new supramolecular system to create hierarchical polymeric architectures under precisely controlled flow conditions, by combining the conventional supramolecular strategy with microfluidic science.
Characterization of Zn‐Containing Metal–Organic Frameworks by Solid‐State 67Zn NMR Spectroscopy and Computational Modeling
Authors: Sutrisno Andre , Terskikh Victor V. , Shi Qi , Song Zhengwei , Dong Jinxiang , Ding San Yuan , Wang Wei , Provost Bianca R. , Daff Thomas D. , Woo Tom K. , Huang Yining 
Published: September 2012

AbstractMetal–organic frameworks (MOFs) are an extremely important class of porous materials with many applications. The metal centers in many important MOFs are zinc cations. However, their Zn environments have not been characterized directly by 67Zn solid‐state NMR (SSNMR) spectroscopy. This is because 67Zn (I=5/2) is unreceptive with many unfavorable NMR characteristics, leading to very low sensitivity. In this work, we report, for the first time, a 67Zn natural abundance SSNMR spectroscopic study of several representative zeolitic imidazolate frameworks (ZIFs) and MOFs at an ultrahigh magnetic field of 21.1 T. Our work demonstrates that 67Zn magic‐angle spinning (MAS) NMR spectra are highly sensitive to the local Zn environment and can differentiate non‐equivalent Zn sites. The 67Zn NMR parameters can be predicted by theoretical calculations. Through the study of MOF‐5 desolvation, we show that with the aid of computational modeling, 67Zn NMR spectroscopy can provide valuable structural information on the MOF systems with structures that are not well described. Using ZIF‐8 as an example, we further demonstrate that 67Zn NMR spectroscopy is highly sensitive to the guest molecules present inside the cavities. Our work also shows that a combination of 67Zn NMR data and molecular dynamics simulation can reveal detailed information on the distribution and the dynamics of the guest species. The present work establishes 67Zn SSNMR spectroscopy as a new tool complementary to X‐ray diffraction for solving outstanding structural problems and for determining the structures of many new MOFs yet to come.
Gold Nanoparticles Grown on Ionic Liquid‐Functionalized Single‐Walled Carbon Nanotubes: New Materials for Photothermal Therapy
Authors: Meng Lingjie , Niu Lvye , Li Ling , Lu Qinghua , Fei Zhaofu , Dyson Paul J. 
Published: September 2012

AbstractGold nanoparticles were grown on single‐walled carbon nanotubes (SWNTs) coated with a thiol‐functionalized ionic liquid resulting in the formation of core‐shell structures referred to as SWNT‐IL‐Au nanohybrid materials. The nanohybrid materials were characterized by high‐resolution transmission electron microscopy (HR‐TEM), Raman‐, and UV/Vis absorption spectroscopy. The nanohybrid materials were found to enter lysosomes in HeLa cells and show negligible cytotoxicity. Interestingly, they have an enhanced NIR absorption that is effectively transferred into heat to cause localized hyperthermia, resulting in rapid cell death; overall, the material appears to have excellent properties for photothermal therapeutic applications.