bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis, Structures and Reactivity of Lanthanoid(II) Formamidinates of Varying Steric Bulk
Authors: Cole Marcus L. , Deacon Glen B. , Forsyth Craig M. , Junk Peter C. , Konstas Kristina , Wang Jun , Bittig Henry , Werner Daniel 
Published: November 2012

AbstractNew reactive, divalent lanthanoid formamidinates [Yb(Form)2(thf)2] (Form=[RNCHNR]; R=o‐MeC6H4 (o‐TolForm; 1), 2,6‐Me2C6H3 (XylForm; 2), 2,4,6‐Me3C6H2 (MesForm; 3), 2,6‐Et2C6H3 (EtForm; 4), o‐PhC6H4 (o‐PhPhForm; 5), 2,6‐iPr2C6H3 (DippForm; 6), o‐HC6F4 (TFForm; 7)) and [Eu(DippForm)2(thf)2] (8) have been prepared by redox transmetallation/protolysis reactions between an excess of a lanthanoid metal, Hg(C6F5)2 and the corresponding formamidine (HForm). X‐ray crystal structures of 2–6 and 8 show them to be monomeric with six‐coordinate lanthanoid atoms, chelating N,N′‐Form ligands and cis‐thf donors. However, [Yb(TFForm)2(thf)2] (7) crystallizes from THF as [Yb(TFForm)2(thf)3] (7 a), in which ytterbium is seven coordinate and the thf ligands are “pseudo‐meridional”. Representative complexes undergo CX (X=F, Cl, Br) activation reactions with perfluorodecalin, hexachloroethane or 1,2‐dichloroethane, and 1‐bromo‐2,3,4,5‐tetrafluorobenzene, giving [Yb(EtForm)2F]2 (9), [Yb(o‐PhPhForm)2F]2 (10), [Yb(o‐PhPhForm)2Cl(thf)2] (11), [Yb(DippForm)2Cl(thf)] (12) and [Yb(DippForm)2Br(thf)] (16). X‐ray crystallography has shown 9 to be a six‐coordinate, fluoride‐bridged dimer, 12 and 16 to be six‐coordinate monomers with the halide and thf ligands cis to each other, and 11 to have a seven‐coordinate Yb atom with “pseudo‐meridional” unidentate ligands and thf donors cis to each other. The analogous terbium compound [Tb(DippForm)2Cl(thf)2] (13), prepared by metathesis, has a similar structure to 11. CBr activation also accompanies the redox transmetallation/protolysis reactions between La, Nd or Yb metals, Hg(2‐BrC6F4)2, and HDippForm, yielding [Ln(DippForm)2Br(thf)] complexes (Ln=La (14), Nd (15), Yb (16)).
Main‐Chain Linear Polyrotaxanes: Synthesis, Characterization, and Conformational Modulation
Authors: Han Ji‐Min , Zhang Yong‐Hong , Wang Xiao‐Ye , Liu Chen‐Jiang , Wang Jie‐Yu , Pei Jian 
Published: November 2012

AbstractTwo functional main‐chain linear polyrotaxanes, one a covalent polymeric chain that threads through many macrocycles (P1) and the other a poly[n]rotaxane chain that is composed of many repeating rotaxane units (P2), were synthesized by employing strong crown‐ether/ammonium‐based (DB24C8/DBA) host–guest interactions and click chemistry. Energy transfer between the wheel and axle units in both polyrotaxanes was used to provide insight into the conformational information of their resulting polyrotaxanes. Steady‐state and time‐resolved spectroscopy were performed to understand the conformation differences between polymers P1 and P2 in solution. Additional investigations by using dynamic/static light scattering and atomic force microscopy illustrated that polymer P1 was unbending and had a rigid rod‐like structure, whilst polymer P2 was curved and flexible. This flexible topology facilitated the self‐assembly of polymer P2 into relatively large ball‐shaped particles. In addition, the energy transfer between the wheel and axle units was controlled by the addition of specific anions or base. The anion‐induced energy enhancement was attributed to a change in electrostatic interactions between the polymer chains. The base‐driven molecular shuttle broke the DB24C8/DBA host–guest interactions. These results confirm that both intra‐ and intermolecular electrostatic interactions are crucial for modulating conformational topology, which determines the assembly of polyrotaxanes in solution.
Laser Spectroscopic Study of Cold Host–Guest Complexes of Crown Ethers in the Gas Phase
Authors: Inokuchi Yoshiya , Kusaka Ryoji , Ebata Takayuki , Boyarkin Oleg V. , Rizzo Thomas R. 
Published: November 2012

AbstractA laser spectroscopic study on the structure and dynamics of cold host–guest inclusion complexes of crown ethers (CEs) with various neutral and ionic species in the gas phase is presented. The complexes with neutral guest species are formed by using supersonic free jets, and those with ionic species are generated with electrospray ionization combined with a cold 22‐pole ion trap. For CEs, various sizes of 3n‐crown‐n ethers (n=4, 5, 6, and 8) and their benzene‐substituted species are used. For the guest species, water, methanol, ammonia, acetylene, and phenol are employed as neutral guest species, and for charged guest species, alkali metal cations are chosen. The electronic and vibrational spectra of the complexes are measured by using various laser spectroscopic methods; electronic spectra for the neutral complexes are measured by laser‐induced fluorescence. Discrimination of different species such as conformers is performed by ultraviolet–ultraviolet hole‐burning spectroscopy. The vibrational spectra of selected species are observed by infrared–ultraviolet double‐resonance (IR–UV DR) spectroscopy. For the ionic complexes, ultraviolet photodissociation and IR–UV DR spectroscopy are applied. The complex structures are determined by comparing the observed spectra with those of possible structures obtained by density functional theory calculations. How the host CEs change their conformation or which conformer prefers to form unique inclusion complexes are discussed. These results reveal the key interactions for forming special complexes leading to molecular recognition.
Photoinduced Triplet–Triplet Energy Transfer in a 2‐Ureido‐4(1H)‐Pyrimidinone‐Bridged, Quadruply Hydrogen‐Bonded Ferrocene–Fullerene Assembly
Authors: Feng Ke , Yu Mao‐Lin , Wang Su‐Min , Wang Ge‐Xia , Tung Chen‐Ho , Wu Li‐Zhu 
Published: November 2012

Abstract2‐Ureido‐4(1H)‐pyrimidinone‐bridged ferrocene–fullerene assembly I is designed and synthesized for elaborating the photoinduced electron‐transfer processes in self‐complementary quadruply hydrogen‐bonded modules. Unexpectedly, steady‐state and time‐resolved spectroscopy reveal an inefficient electron‐transfer process from the ferrocene to the singlet or triplet excited state of the fullerene, although the electron‐transfer reactions are thermodynamically feasible. Instead, an effective intra‐assembly triplet–triplet energy‐transfer process is found to be operative in assembly I with a rate constant of 9.2×105 s−1 and an efficiency of 73 % in CH2Cl2 at room temperature.
Serum adipokines as biomarkers of beta‐cell function in patients with type 1 diabetes: positive association with leptin and resistin and negative association with adiponectin
Authors: Pham Minh Nguyet , Kolb Hubert , Mandrup‐Poulsen Thomas , Battelino Tadej , Ludvigsson Johnny , Pozzilli Paolo , Roden Michael , Schloot Nanette C. ,   European C‐Peptide Trial
Published: November 2012

AbstractBackgroundWe investigated the adipokines adiponectin, leptin and resistin as serum biomarkers of beta‐cell function in patients with type 1 diabetes.MethodsOne hundred and eighteen patients with type 1 diabetes (20.3 ± 7.5 years) diagnosed <5 years underwent standardized mixed meal test (MMTT) for 2 h. Systemic concentrations of C‐peptide, adiponectin, leptin and resistin obtained during MMTT were measured and compared between patient groups by multiple regression analysis.ResultsPatients were divided by their adipokine levels in subgroups above or below the median level (‘high versus low’). High adiponectin levels (>10.6 µg/mL) were associated with lower C‐peptide compared to the low adiponectin subgroup (p < 0.03). Increased leptin or resistin concentrations associated positively with beta‐cell function even after adjustment for metabolic confounders (p < 0.04). The described associations between adipokines and C‐peptide concentrations persisted in Spearman correlation tests (p < 0.05). Serum adipokines fell during MMTT (p < 0.05).ConclusionsSerum adipokine levels differentially correlate with beta‐cell function in type 1 diabetes independent of BMI or metabolic control. Serum adipokines should be investigated as biomarkers of beta‐cell function in prospective studies and intervention trials in type 1 diabetes. Copyright © 2012 John Wiley & Sons, Ltd.
Evolution of sex comb from the primitive bristle pattern in drosophila is associated with modification in the developmental regulatory protein dachshund
Authors: Devi Thangjam Ranjita , Amruthavalli C. , Shyamala B.V. 
Published: November 2012

AbstractSex comb is a recently evolved male specific character confined to the Sophophoran group of Drosophila. Such innovations in phenotypes as Waddington proposed, are, outcome of “canalization” in developmental pathways that occur due to mutations creating “choice points” in genetic regulatory pathways. Our interest in the present study is to understand the shifts in genetic network, which has lead to the origin of sex comb from the basic bristle pattern that is seen in rest of the members of Drosophilidae. Here we have made a comparative analysis of expression of some of the key regulators of sex comb morphogenesis, between D. melanogaster and a group of selected species, which primitively lack sex comb. Sex combs reduced (Scr), dachshund (dac), and bric‐a‐brac (bab) gene expression were studied. We show that, primitive bristle pattern is marked by a strikingly down regulated expression of Sex combs reduced in the first tarsal segment of the prothoracic leg discs of male flies. Further a remarkable change with respect to Dachshund, an activator of sex combs reduced gene in the sex comb regulatory pathway, is seen. This is attributed to changes in DAC protein that might have taken place between the two groups of species. bric‐a‐brac does not reveal any significant expression modulation between the sex comb bearing and the primitive patterned species. Earlier works had shown that within the Sophophoran group, dynamic changes in SCR expression is responsible for the diversity seen in sex comb morphology, where as no such variation is witnessed with respect to DAC expression. Our findings have demonstrated that the scenario is different between the group primitively lacking sex comb and D. melanogaster wherein an obvious change in the protein has taken place. genesis 51:97–109,
2013, 2013. © 2012 Wiley Periodicals, Inc.
{Ce10Mn8}: Cerium Analogues of the Decavanadate Archetype
Authors: Malaestean Iurie L. , Ellern Arkady , Kögerler Paul 
Published: November 2012

AbstractIn the presence of structure‐directing isobutyrate (ib) ligands, CeIII and MnII salts undergo a sequence of oxidation and condensation steps, which result in the intermittent formation of the neutral coordination cluster [Mn10O2(ib)18(Hib)2], followed by Mn‐decorated {Ce10Mn8} clusters. Their common inorganic {CeIV10MnII2MnIII6O18} core features a cerium oxide substructure with a decavanadate‐type metal framework, which showcases that molecular cerium oxide structures indeed can adopt certain structural principles of classical polyoxometalates. In addition, we identified the exact composition and structure of the precursor “manganese isobutyrate”, which actually consists of [Mn6(ib)12(Hib)6] macrocycles.
Synthesis of the N‐Substituted Pyridin‐1(2H)‐one Framework by Ligand‐Assisted Pd‐Catalyzed Reactions
Authors: Zhou Kang , Wen Ping , Chen Wenlin , Ma Chaowei , Huang Guosheng 
Published: November 2012

AbstractAn efficient Pd‐catalyzed method for the synthesis of N‐substituted pyridin‐1(2H)‐ones was developed. The corresponding derivatives, which can be found in numerous biologically active compounds, were obtained in good to excellent yields. A possible mechanism for this reaction is discussed.
Genetic and epigenetic alterations of WWOX in the development of gastric cardia adenocarcinoma
Authors: Guo Wei , Dong Zhiming , Dong Yuran , Guo Yanli , Kuang Gang , Yang Zhibin 
Published: November 2012

AbstractWWOX is a tumor suppressor gene that maps to the common fragile site FRA16D and is involved in carcinogenesis and cancer progression in many different carcinomas. Reduced WWOX expression is associated with more aggressive phenotypes and poor patient outcomes in several cancers. The present study was conducted in order to elucidate more precisely the genetic and epigenetic alterations of WWOX that play a role in gastric cardia adenocarcinoma (GCA) carcinogenesis in a population from Northern China. Polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP), PCR‐simple sequence length polymorphism (PCR‐SSLP), and methylation specific PCR (MSP) methods were used to characterize polymorphisms in the rs3764340, rs2548861, and rs1079635 loci, the level of loss of heterozygosity (LOH), and methylation status of WWOX, respectively. Protein and mRNA expression of WWOX in GCA tissues was quantified by immunohistochemistry and reverse transcription‐PCR (RT‐PCR). Family history of upper gastrointestinal cancer (UGIC) significantly increased the risk of developing GCA. The CG+GG genotype of rs3764340 and GT or TT genotype of rs2548861 significantly elevated the risk of developing GCA. LOH at the WWOX locus was observed in 45.6% tumors. The promoter and exon 1 methylation frequency of WWOX in GCA tissues was significantly higher than in corresponding normal tissues and was associated with UGIC family history. Protein and mRNA expression of WWOX was reduced in GCA tumor tissues and was associated with LOH and methylation of the gene. These results indicate that WWOX may play an important role in GCA especially in individuals with UGIC family history. Environ. Mol. Mutagen., 2013. © 2012 Wiley Periodicals, Inc.
Effect of TiO2 scaffolds coated with alginate hydrogel containing a proline‐rich peptide on osteoblast growth and differentiation in vitro
Authors: Rubert M. , Pullisaar H. , Gómez‐Florit M. , Ramis J. M. , Tiainen H. , Haugen H. J. , Lyngstadaas S. P. , Monjo M. 
Published: November 2012

AbstractThe aim of this study was to investigate the effect of TiO2 scaffold (SC) coated with an alginate hydrogel containing a proline‐rich peptide (P2) on osteoblast proliferation and differentiation in vitro. Peptide release was evaluated and a burst release was observed during the first hours of incubation, and then progressively released overtime. No changes were observed in the cytotoxicity after 48 h of seeding MC3T3‐E1 cells on the coated and uncoated TiO2 SC. The amount of cells after 7 days was higher on uncoated TiO2 SC than on alginate‐coated TiO2 SC, measured by DNA content and scanning electron microscope imaging. In addition, while lower expression of integrin beta1 was detected for alginate‐coated TiO2 SC at this time point, similar gene expression was observed for other integrins, fibronectin‐1, and several osteoblast differentiation markers. After 21 days, gene expression of integrin beta3, fibronectin‐1, osterix, and collagen‐I was increased in alginate‐coated compared to TiO2 SC. Moreover, increased gene expression of integrin alpha8, bone morphogenetic protein 2, interleukin‐6, and collagen‐I was found on P2 alginate‐coated TiO2 SC compared to alginate‐coated TiO2 SC. In conclusion, our results indicate that alginate‐coated TiO2 SC can act as a matrix for delivery of proline‐rich peptides increasing osteoblast differentiation. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Mathematical modeling of RDC column in extraction of base oil and computing of the energy saving
Authors: FakhrHoseini Seyed Mousa , Tavakkoli Touraj , Hatamipour Mohammad Sadegh , Mehrkesh Amir Hossein 
Published: November 2012

AbstractBackgroundA mathematical modeling approach was used to obtain a simulation model to predict the performance of an industrial rotating disc contactor (RDC) in the extraction of lubricating base oils by furfural. The field data of a lube‐oil producing plant was used to validate the model. This model can be used for the parametric study of the RDC column and to investigate the effect of operational data such as solvent and feed temperatures, solvent to feed ratio, and agitation rate on the yield of extraction and on the energy saving value of the extraction.ResultsThe mathematical modeling of RDC shows good agreement with the plant data with an accuracy of 95% and the model was used to investigate the effect of adding a co‐solvent.ConclusionResults show that by using furfural with added 2,2,4 trimethylpentane it is possible to perform the extraction process at a lower process temperature, 363.15 K, compared with 393.15 K using furfural as solvent, and also at a lower 1.3 solvent/feed ratio, compared with 1.5 when furfural alone was used for as the solvent. This process modification leads to saving of 38% of the consumed energy per cubic meter of product in the extraction process.© 2012 Society of Chemical Industry
Biomechanics of Turtle Shells: How Whole Shells Fail in Compression
Authors: Magwene Paul M. , Socha John J. 
Published: November 2012

AbstractTurtle shells are a form of armor that provides varying degrees of protection against predation. Although this function of the shell as armor is widely appreciated, the mechanical limits of protection and the modes of failure when subjected to breaking stresses have not been well explored. We studied the mechanical properties of whole shells and of isolated bony tissues and sutures in four species of turtles (Trachemys scripta, Malaclemys terrapin, Chrysemys picta, and Terrapene carolina) using a combination of structural and mechanical tests. Structural properties were evaluated by subjecting whole shells to compressive and point loads in order to quantify maximum load, work to failure, and relative shell deformations. The mechanical properties of bone and sutures from the plastral region of the shell were evaluated using three‐point bending experiments. Analysis of whole shell structural properties suggests that small shells undergo relatively greater deformations before failure than do large shells and similar amounts of energy are required to induce failure under both point and compressive loads. Location of failures occurred far more often at sulci than at sutures (representing the margins of the epidermal scutes and the underlying bones, respectively), suggesting that the small grooves in the bone created by the sulci introduce zones of weakness in the shell. Values for bending strength, ultimate bending strain, Young's modulus, and energy absorption, calculated from the three‐point bending data, indicate that sutures are relatively weaker than the surrounding bone, but are able to absorb similar amounts of energy due to higher ultimate strain values. J. Exp. Zool. 319A:86–98, 2012. © 2012 Wiley Periodicals, Inc.
Anteroposterior variation of the cell types in the interrenal gland of the male toad Rhinella arenarum (Amphibia, Anura)
Authors: Regueira Eleonora , Scaia María Florencia , Volonteri María Clara , Ceballos Nora Raquel 
Published: November 2012

AbstractThe interrenal gland of anurans synthesizes the steroids aldosterone and corticosterone, but it is unknown whether these hormones are synthesized by the same cell type. In this work, we aim to elucidate whether there are different steroidogenic cell types and whether they have specific regionalization in the interrenal gland of the male toad Rhinella arenarum. We characterized all cell types using histological, immuhistochemical, and histochemical methods as well as transmission electron microscopy. Furthermore, we evaluated the organization of the cell types in the gland and anteroposterior variations in the synthesis of the steroids. We found evidence of five cell types: two morphologically different steroidogenic cells, type 1: polyhedral cells tightly attached to each other that have spherical euchromatic nuclei and type 2: retracted cells loosely attached to each other that have oval heterochromatic nuclei. Cell type 2 is mainly observed in the inner zone of the gland. In addition, we observed two types of chromaffin cells, called type 3 and 4 cells, randomly distributed throughout the interrenal gland, as well as type 5 cells, recognized as summer cells. Morphometric analyses of the cell types in the anterior and posterior zones of the interrenal showed that the ratio “area of type 2 cells/total interrenal area” is significantly lower in the posterior zone. In vitro incubations showed that the posterior portion of the gland produces significantly higher amounts of both corticosterone and aldosterone. Overall, our results suggest that the type 2 cells are less active to synthesize both aldosterone and corticosterone, compared to type 1 cells. Unlike most previous reports on the interrenal gland of anurans, in R. arenarum there is a zonation of the steroidogenic cell types, which implies that the organ is not anteroposterior or dorsoventrally homogeneous. © J. Morphol., 2013. © 2012 Wiley Periodicals, Inc.
Chronic exposure of lung alveolar epithelial type II cells to tobacco‐specific carcinogen NNK results in malignant transformation: A new in vitro lung carcinogenesis model
Authors: Mennecier Gregory , Torres Luciana N. , Cogliati Bruno , Sanches Daniel S. , Mori Claudia M. , Latorre Andréia O. , Chaible Lucas M. , Mackowiak Ivone I. , Nagamine Marcia K. , Da Silva Tereza C. , Fukumasu Heidge , Dagli Maria Lucia Zaidan 
Published: November 2012

AbstractLung cancer is the leading cause of cancer‐related mortality in both men and women throughout the world. This disease is strongly associated with tobacco smoking. The aim of this manuscript was to establish an in vitro model that mimics the chronic exposures of alveolar epithelial type II cells to the tobacco‐specific nitrosamine carcinogen, NNK. Immortalized non‐neoplastic alveolar epithelial cells type II, (E10 cells), from BALB/c mice were exposed to low concentration of NNK (100 pM) during 5, 10, 15, and 20 cycles of 48 h. NNK‐transformed cells showed an increase of proliferation rate and motility. Moreover, these cells underwent epithelial‐to‐mesenchymal transition (EMT). Increased migratory capacity and EMT were correlated to the time of exposure to NNK. NNK‐transformed cells were tested for their growth and metastatic capacity in vivo. Subcutaneous injection of cells exposed to NNK for 20 cycles (E10‐NNK20 clone) into BALB/c mice led to the formation of subcutaneous tumors that arose after 40 ± 17 d in all animals, which died 95 ± 18 d after cell inoculation, with lymph nodes and lung metastasis. The morphological characteristics of tumors were compatible with metastatic undifferentiated carcinoma. Cells exposed to NNK for 5–10 cycles did not display metastatic capacity, while those exposed for 15 cycles displayed low capacity. Our results show that prolonged exposures to NNK led the cells to increasingly acquire malignant properties. The cellular model presented in this study is suitable for studying the molecular events involved in the different stages of malignant transformation. © 2012 Wiley Periodicals, Inc.
CORAL: Monte Carlo Method as a Tool for the Prediction of the Bioconcentration Factor of Industrial Pollutants
Authors: Toropova A. P. , Toropov A. A. , Martyanov S. E. , Benfenati E. , Gini G. , Leszczynska D. , Leszczynski J. 
Published: November 2012

AbstractThe CORAL software (http://www.insilico.eu/coral/) has been evaluated for application in QSAR modeling of the bioconcentration factor in fish (logBCF). The data used include 237 organic substances (industrial pollutants). Six random splits of the data into sub‐training (30–50 %), calibration (20–30 %), test (13–30 %), and validation sets (7–25 %) have been carried out. The following numbers display the average statistical characteristics of the models for the external validation set: correlation coefficient r2=0.880±0.017 and standard error of estimation s=0.559±0.131. The best models were obtained with a combined representation of the molecular structure by SMILES together with hydrogen suppressed graph.