bluuebunny/crossref_metadata_2025_split huggingface dataset:
Palmarumycins from the Endophytic Fungus Lasiodiplodia pseudotheobromae XSZ‐3
Authors: Lü Xiaojing , Chen Gang , Li Zhanlin , Zhang Yuhong , Wang Zaiying , Rong Weiwei , Pei Yuehu , Pan Huaqi , Hua Huiming , Bai Jiao 
Published: September 2014

AbstractOne new and three known spiro‐dioxynaphthalene compounds, related to palmarumycins, were isolated from the extracts of fungus Lasiodiplodia pseudotheobromae XSZ‐3. Their structures were established by spectroscopic methods (1D‐ and 2D‐NMR, HR‐ESI‐MS, etc.). The absolute configuration of 1 was determined by comparison of quantum‐chemical TDDFT (time‐dependent density‐functional theory) calculated and experimental ECD (electronic circular dichroism) spectra. The cytotoxic activities of 1–4 against HL‐60 cell line were evaluated by trypan blue‐staining assay.
Oligonucleotide Analogues with Integrated Bases and Backbone. Part 32
Authors: Schulze‐Adams Martina , Bernet Bruno , Touboul David , Egli Daniel , Herdeis Lorenz , Vasella Andrea 
Published: September 2014

AbstractThe G[s]G dinucleoside 6 and the G[s]G* dinucleoside 8 were prepared by alkylation of the guanosine thiols derived from 2 and 5, respectively, by the C(8)‐chloromethylated guanosine 4 that was obtained from alcohol 3. Dinucleosides 6 and 8 were deacylated to 7 and 9, and fully deprotected to 10 and 11, respectively. The G[n]G dinucleoside 16 was obtained by reductive amination of aldehyde 13 with an iminophosphorane derived from azide 14 and deprotection of the resulting dimer 15. In the solid state of 6, and in a solution of 6 and 8 in CDCl3, HN(1/I) and HN(1/II) are engaged in intramolecular H‐bonds to the CO of the isobutyryl protecting groups, and HN of the isobutyryl group of unit I forms an interresidue, intramolecular H‐bond to N(7/II), leading to a syn orientation of the nucleobase at unit I, to a tg orientation of the sulfanyl moiety, and to an orthogonal orientation of the nucleobases, preventing any base pairing. The silylated and isopropylidenated dinucleosides 7 and 9 are present in DMSO solution as solvated monoplexes. Broad 1H‐NMR signals of the nucleosides 7 and 16 in CHCl3 solution evidence equilibrating G‐quadruplexes. The quadruplex formation of 7 and 16 was established by 1H‐NMR spectroscopy (only of 16), vapour pressure osmometry, mass spectrometry, and CD spectroscopy. The C(6(I))‐hydroxymethylated analogue 9 in CDCl3 and the fully deprotected dinucleosides 10 and 11 in H2O form only weakly ππ stacked associates, but no G‐quadruplexes, as evidenced by CD spectroscopy.
MRT Letter: Guided filtering of image focus volume for 3D shape recovery of microscopic objects
Authors: Mahmood Muhammad Tariq 
Published: September 2014

ABSTRACTIn this letter, a shape from focus (SFF) method is proposed that utilizes the guided image filtering to enhance the image focus volume efficiently. First, image focus volume is computed using a conventional focus measure. Then each layer of image focus volume is filtered using guided filtering. In this work, the all‐in‐focus image, which can be obtained from the initial focus volume, is used as guidance image. Finally, improved depth map is obtained from the filtered image focus volume by maximizing the focus measure along the optical axis. The proposed SFF method is efficient and provides better depth maps. The improved performance is highlighted by conducting several experiments using image sequences of simulated and real microscopic objects. The comparative analysis demonstrates the effectiveness of the proposed SFF method. Microsc. Res. Tech. 77:959–963, 2014. © 2014 Wiley Periodicals, Inc.
Evaluating the thermal effects of translocation in a large‐bodied pitviper
Authors: Holding Matthew L. , Owen Dustin A.S. , Taylor Emily N. 
Published: September 2014

ABSTRACTAcute stressors can be costly, often requiring alteration of normal physiological processes to mitigate their effects. Animal translocation may be a very stressful event and result in a reduced ability to maintain homeostasis. The impacts of translocation on the thermal ecology of ectothermic vertebrates, which may rely on preferred habitats for thermoregulation, are currently unknown. In this study, 22 adult male Northern Pacific rattlesnakes (Crotalus oreganus oreganus) were implanted with automated temperature loggers and radio‐tracked. Snakes were assigned to one of three treatments: translocation, handling control, and undisturbed control. Short‐distance translocation (SDT) and handling treatments were applied weekly for 6 weeks. Hourly body temperature (Tb) was recorded during the course of the study. Mean Tb was impacted in a time‐dependent fashion, where translocated snakes had lower mean Tb than handled controls during the first week of the study only, especially the first 24 hr after translocation. Separating the dataset into day and night revealed that this effect was localized to Tb variation during the day only. Variance in temperature was not impacted by translocation or handling. Snake body mass and time of year were the major factors influencing the thermal profiles of these rattlesnakes. Thermal ecology in male rattlesnakes is resilient to SDT, suggesting that they quickly resume normal behaviors following repeated bouts of acute capture stress and disturbance of their spatial ecology. This study provides support for SDT as a safe measure for mitigating human–snake interactions and facilitating conservation practices regarding male snakes, which are the most frequently encountered sex. J. Exp. Zool. 321A: 442–449, 2014. © 2014 Wiley Periodicals, Inc.
Sensory perceptions of individuals exposed to the static field of a 7T MRI: A controlled blinded study
Authors: Friebe Björn , Wollrab Astrid , Thormann Markus , Fischbach Katharina , Ricke Jens , Grueschow Marcus , Kropf Siegfried , Fischbach Frank , Speck Oliver 
Published: September 2014

PurposeTo determine the subjective experience of subjects undergoing 7T magnetic resonance imaging (MRI) compared to a mock scanner with no magnetic field.Methods and MaterialsIn all, 44 healthy subjects were exposed to both the B0 field of a 7T whole‐body MRI and a realistic mock scanner with no magnetic field. Subjects were blinded to the actual field strength and no scanning was performed. After exposure, subjects rated their experience of potential sensory perceptions.ResultsThe most frequently observed side effect was vertigo while entering the gantry, which was reported by 38.6% (n = 17). Other frequent side effects were the appearance of phosphenes (18.2%, n = 8), thermal heat sensation (15.9%), unsteady gait after exposure (13.6%, n = 6), and dizziness (13.6%). All side effects were reported significantly more often after 7T exposure. Nine subjects (20.5%) did not report any sensory perceptions at all, ie, neither in the 7T scanner nor in the mock scanner.ConclusionLight, acute, and transient sensory perceptions can occur in subjects undergoing ultrahighfield MRI, of which vertigo seems to be the most frequently reported. Possible psychological effects might contribute to the emergence of such sensory perceptions, as some subjects also reported them to appear in a realistic mock scanner with no magnetic field. J. Magn. Reson. Imaging 2015;41:1675–1681. © 2014 Wiley Periodicals, Inc.
Interspecies comparison of subchondral bone properties important for cartilage repair
Authors: Chevrier Anik , Kouao Ahou S. M. , Picard Genevieve , Hurtig Mark B. , Buschmann Michael D. 
Published: September 2014

ABSTRACTMicrofracture repair tissue in young adult humans and in rabbit trochlea is frequently of higher quality than in corresponding ovine or horse models or in the rabbit medial femoral condyle (MFC). This may be related to differences in subchondral properties since repair is initiated from the bone. We tested the hypothesis that subchondral bone from rabbit trochlea and the human MFC are structurally similar. Trochlea and MFC samples from rabbit, sheep, and horse were micro‐CT scanned and histoprocessed. Samples were also collected from normal and lesional areas of human MFC. The subchondral bone of the rabbit trochlea was the most similar to human MFC, where both had a relatively thin bone plate and a more porous and less dense character of subchondral bone. MFC from animals all displayed thicker bone plates, denser and less porous bone and thicker trabeculae, which may be more representative of older or osteoarthritic patients, while both sheep trochlear ridges and the horse lateral trochlea shared some structural features with human MFC. Since several cartilage repair procedures rely on subchondral bone for repair, subchondral properties should be accounted for when choosing animal models to study and test procedures that are intended for human cartilage repair. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:63–70, 2015.
Influence of low‐molecular‐weight glutenin subunit genes at Glu‐A3 locus on wheat sodium dodecyl sulfate sedimentation volume and solvent retention capacity value
Authors: Li Zhixia , Si Hongqi , Xia Yunxiang , Ma Chuanxi 
Published: September 2014

AbstractBACKGROUNDTo understand the effect of low‐molecular‐weight (LMW) glutenin alleles at the Glu‐A3 locus on sodium dodecyl sulfate (SDS) sedimentation volume and solvent retention capacity (SRC) values, 244 accessions of Chinese wheat (Triticum aestivum L.) mini core collections were investigated. In this study the significant differences in wholemeal flour SDS sedimentation volume and SRC values associated with specific glutenin alleles at the Glu‐A3 locus were explained.RESULTSSeven glutenin alleles at the Glu‐A3 locus were confirmed by locus‐specific polymerase chain reaction (PCR). SDS sedimentation volume and lactic acid SRC value were significantly affected by alleles Glu‐A3b and Glu‐A3g. Based on total average values, 28 varieties carrying Glu‐A3b had significantly higher means of SDS sedimentation volume and lactic acid SRC value, whereas 19 varieties carrying Glu‐A3g had significantly lower means. Alleles Glu‐A3d and Glu‐A3f significantly increased only SDS sedimentation volume and sucrose SRC value respectively. Correlation analysis showed that SDS sedimentation volume was uncorrelated with lactic acid SRC and sucrose SRC values.CONCLUSIONThe Glu‐A3 LMW glutenin subunit could predict 12.8% of the variance in SDS sedimentation volume, 4.7% in lactic acid SRC and 6.4% in sucrose SRC. © 2014 Society of Chemical Industry
First Acyclic Diene Metathesis Polymerization Under Biphasic Conditions Using a Dicationic Ruthenium Alkylidene: Access to High‐Molecular‐Weight Polymers with Very Low Ruthenium Contamination
Authors: Zhao Jing , Wang Dongren , Autenrieth Benjamin , Buchmeiser Michael R. 
Published: September 2014

The acyclic diene metathesis (ADMET) polymerization of 6‐hydroxy‐1,10‐undecadiene (M1) and 6‐acetoxy‐1,10‐undecadiene (M2) by the action of two different catalysts, i.e., the second‐generation Grubbs‐Hoveyda system ([RuCl2(IMesH2)(CH‐2‐(2‐PrO‐C6H4)]) (1) and the dicationic ruthenium alkylidene [Ru(DMF)3(IMesH2)(CH‐2‐(2‐PrO‐C6H4)] (2, IMesH2 = 1,3‐dimesitylimidazolin‐2‐ylidene) is reported. Biphasic conditions using 1‐butyl‐2,3‐dimethylimidazolium tetrafluoroborate ([BDMIM+BF4−]) and 1,2,4‐trichlorobenzene (TCB) are applied. Under the chosen conditions (T = 75 °C, 20 mbar), the use of catalyst 1 results only in the formation of low‐molecular‐weight polymers ( ≤ 10 000 g mol−1), while catalyst 2 allows for the high yield synthesis of high‐molecular‐weight polymers ( ≤ 40 000 g mol−1, yields ≤ 99%). Irrespective of the catalyst used, all polymers display a high trans‐content (>95%). Notably, Ru‐contamination of the target polymers without any additional purification is as low as 1.2 ppm with catalyst 2. Together with the high yields and high molecular weights, the low Ru‐contaminations clearly illustrate the advantages of the biphasic setup.
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Bayesian analysis of transverse signal decay with application to human brain
Authors: Bouhrara Mustapha , Reiter David A. , Spencer Richard G. 
Published: September 2014

PurposeTransverse relaxation analysis with several signal models has been used extensively to determine tissue and material properties. However, the derivation of corresponding parameter values is notoriously unreliable. We evaluate improvements in the quality of parameter estimation using Bayesian analysis and incorporating the Rician noise model, as appropriate for magnitude MR images.Theory and MethodsMonoexponential, stretched exponential, and biexponential signal models were analyzed using nonlinear least squares (NLLS) and Bayesian approaches. Simulations and phantom and human brain data were analyzed using three different approaches to account for noise. Parameter estimation bias (reflecting accuracy) and dispersion (reflecting precision) were derived for a range of signal‐to‐noise ratios (SNR) and relaxation parameters.ResultsAll methods performed well at high SNR. At lower SNR, the Bayesian approach yielded parameter estimates of considerably greater precision, as well as greater accuracy, than did NLLS. Incorporation of the Rician noise model greatly improved accuracy and, to a somewhat lesser extent, precision, in derived transverse relaxation parameters. Analyses of data obtained from solution phantoms and from brain were consistent with simulations.ConclusionOverall, estimation of parameters characterizing several different transverse relaxation models was markedly improved through use of Bayesian analysis and through incorporation of the Rician noise model. Magn Reson Med 74:785–802, 2015. © 2014 Wiley Periodicals, Inc.
ZTE imaging with enhanced flip angle using modulated excitation
Authors: Schieban Konrad , Weiger Markus , Hennel Franciszek , Boss Andreas , Pruessmann Klaas P. 
Published: September 2014

PurposeZero echo time (ZTE) imaging is a fast, robust, and silent three‐dimensional technique for direct MRI of tissues with rapid transverse relaxation. It is conventionally performed with hard, block‐shaped excitation pulses short enough to excite spins uniformly over a large bandwidth. With this approach, the achievable flip angle (FA) is limited by the available B1 amplitude. The purpose of this work is to accomplish ZTE imaging with larger FAs by combined amplitude and frequency modulation of the excitation pulse while keeping the pulse duration short enough to limit acquisition dead time.MethodsQuantitative performance criteria for FA yield and uniformity of radio frequency (RF) pulses were developed and used to optimize hyperbolic secant pulse shapes. The RF pulses were implemented on a 4.7 T animal MRI system, included in algebraic image reconstruction, and tested in experiments on phantoms and tissue samples.ResultsThe optimized modulated pulses provide considerably improved performance with respect to uniformity and mean FA as compared with block‐shaped counterparts of the same maximum length. Using these pulses, ZTE images of excellent uniformity were obtained with enhanced FA and thus expanded contrast versatility.ConclusionThe performance of ZTE imaging can be significantly improved by employing optimized short amplitude‐ and frequency‐modulated RF pulses. Magn Reson Med 74:684–693, 2015. © 2014 Wiley Periodicals, Inc.
A post‐mortem stereological study of striatal cell number in human obesity
Authors: Weise Christopher M. , Mouton Peter R. , Eschbacher Jennifer , Coons Stephen W. , Krakoff Jonathan 
Published: September 2014

ObjectiveNeuroimaging studies have revealed abnormalities in brain structure, including the striatum, in obese people. In this study, the cellular and parenchymal basis for these findings in post‐mortem brain tissue was investigated.MethodsDesign‐based (unbiased) stereology combined with histochemical and immunocytochemical staining was used to quantify total number of neurons and astrocytes in post‐mortem striatal brain samples from nine obese (BMI 40.2 ± 6.1 kg/m2) and eight lean (BMI 24.4 ± 1.0 kg/m2) donors. Total numbers of Nissl‐stained neurons and glial fibrillary acidic protein‐immunopositive astrocytes were counted in 10 systematic‐random sections starting from the frontal pole of the striatum.ResultsThere were no differences in mean total numbers of neurons (obese: 7.60 E+06; SD 2.50 E+06; lean: 7.85 E+06; SD 8.26 E+05; P < 0.78) or astrocytes (obese: 7.42 E+06; SD 2.27 E+06; lean: 7.43 E+06; SD 2.50 E+06; P < 0.99). A higher variance was found for number of neurons (P < 0.007) but not astrocytes (P < 0.72) in the obese group. Neuron/glia ratios were similar in both groups (obese: 1.07, SD 0.39; lean: 1.15, SD 0.37; P < 0.70) with an overall striatal neuron/glia ratio of 1.11 (SD 0.37) across the entire study population (n = 17).ConclusionsNo difference was found in the average numbers of neurons and astrocytes in the anterior striatum between lean and obese people. The morphological basis for structural brain changes in obesity requires further investigation.
Electron spin resonance investigations on graft copolymerization I. Poly(tetrafluoroethylene)–styrene system
Authors: Dobó J. , Hedvig P. 
Published: September 2014

AbstractThe decay of peroxy radicals was measured during the course of grafting styrene onto irradiated poly(tetrafluoroethylene) films. A linear decay was observed up to the time when the film was grafted through its whole thickness. The results of the electron spin resonance measurements could be correlated with the kinetic picture given earlier. In some cases, as a result of grafting, the appearance of fluorocarbon radicals was observed.
Systems for stereospecific polymerization of butadiene based on π‐crotyl and cyclopentadienyl complexes of transition metals
Authors: Tinyakova E. I. , Alferov A. V. , Golenko T. G. , Dolgoplosk B. A. , Oreshkin I. A. , Sharaev O. K. , Chernenko G. N. , Yakovlev V. A. 
Published: September 2014

Abstractπ‐Allyl systems based on bis‐π‐crotyl nickel in combination with halides of other metals were shown to be catalysts for the stereospecific polymerization of dienes. Correlation was made between the nature of the halogen in the active center (π‐allyl complex of nickel) and the microstructure of the polymer chain. The systems containing atoms of chlorine and iodine exhibit maximum stereospecificity and yield cis‐and trans‐polybutadiene, respectively. Bis‐π‐crotyl nickel provides the quantitative formation of the cyclic trimer of butadiene, predominantly trans,trans,trans‐isomer. Nickel hydrides in combination with transition metal halides and Lewis acids were shown to initiate the cis‐polymerization of butadiene. The process proceeds via the formation of π‐crotyl complexes of Ni and other metals. Systems based on biscyclopentadienylnickel and Lewis acids capable of producing stereoregular cis‐ and trans‐polybutadienes were investigated. Crotyl derivatives of chromium and titanium provide the formation of 1,2‐polybutadiene, while in combination with NiCl2 or TiI4, these crotyl derivatives are instrumental in producing 1,4‐cis‐polybutadiene. Addition of 1–2 oxygen atoms/molecule of triscrotyl chromium leads to formation of 1,4‐trans‐polybutadiene. Experimental evidence obtained indicates that the diene polymerization with chromium oxide catalyst involves the active centers of π‐allylic nature.
Synthesis and investigation of polyoxadiazoles
Authors: Korshak V. V. , Krongauz E. S. , Rusanov A. L. 
Published: September 2014

AbstractBy low temperature solution polycondensation in hexamethylphosphoramide of dicarboxylic acid dichlorides and dihydrazides of dicarboxylic acids or bisamidoximes, high molecular compounds with 1,3,4‐ and 1,2,4‐oxadiazole rings in the main chains have been prepared. Some features of the polycyclization reaction as well as the structure and properties of polymers obtained are discussed.
Investigation of branched polyarylates
Authors: Pavlova S. A. , Dubrovina L. V. , Timofeeva G. I. 
Published: September 2014

AbstractIn this paper is given an analysis of the results of the investigation of the polydispersity of polycondensation products, with linear polyarylates as an example. It has been shown that with an increase of the extent of reaction in the process of high‐temperature polycondensation, the role of the interchange reactions grows, leading to the permutation of the units of macromolecules. As a result of such permutation of the units the polydispersity of the samples obtained by the high‐temperature polycondensation decreases. For the products of the interphase polycondensation the coefficient of the polydispersity remains near two, regardless of the extent of reaction. The investigation of this work has shown that the MWD of the branched polyarylates resulting from the high‐temperature polycondensation is greatly influenced by the reaction of polycondensation equilibrium. In spite of the high degree of branching the polydispersity coefficient remains the same as for the linear polyarylates. It has been shown that the Zimm‐Stockmayer theory for the polyarylates in question gives more actual values of branching than the Zimm Kilb theory. The found empirical dependence between the parameters of the Mark‐Houwink equation for linear and branched polyarylates K = 0.268 (6.03 10−5)a is similar to that found earlier for the polyamides and polyesters.
The study of elementary stages in propylene polymerization catalyzed by VCl3–Al(i‐Bu)3
Authors: Novokshonova L. A. , Tsvetkova V. I. , Chirkov N. M. 
Published: September 2014

AbstractThe kinetics of propylene polymerization by a catalyst VCl3–Al(i‐Bu)3 and the molecular weight of polypropylene were studied within a pressure range of 60–500 mm. at 30–60°C. It was shown that within the range of sufficiently high monomer pressures the first reaction order with respect to the monomer is fulfilled, where chain limitation by the monomer is predominant. In the range of low monomer pressures, involving an increase of reaction order with respect to the monomer to the second for a limiting case, chain growth limitation by the alkyl metal and by spontaneous disproportionation play an important part. At 60°C. the constant of chain growth limitation by the monomer is almost 1.5 times higher than that for the alkyl metal and 40 times higher than that for spontaneous limitation. At least a part of the two latter reactions represents termination, after which the rate constant of addition to the active center for the first monomer molecule will be that of initiation which is lower than that of chain growth rate.
Investigation in the field of radiation‐induced solid‐state polymerization. XII. γ‐radiation‐initiated copolymerization of acrylic acid and acrylic amide in the solid, liquid, and supercooled liquid phase
Authors: Hardy Gyula , Nagy Lajos 
Published: September 2014

AbstractThe phase diagram of the acrylic amide–acrylic acid solid system is characterized by two eutectic compositions and by a molecular compound of 1:2 mole proportion with a maximum melting point. In the solid phase the rate of the copolymerization is the highest at the eutectic composition and passes through a minimum at the composition of the molecular compound. The composition of the copolymer formed in the solid phase reflects the structure of the solid phase and differs from the composition determined by the relative reactivity constants. In the supercooled liquid‐phase copolymerization proceeds at a higher rate than in the solid phase and probably according to an ionic mechanism.
Investigation of the radiation polymerization behaviors in the supercooled liquid and mesomorphous phase
Authors: Hardy Gy. , Fedorova N. , Kovács G. , Boros‐Gyevi J. 
Published: September 2014

AbstractPolymerization of N‐vinylcaprolactam, dimethylitaconate, and vinylchloroacetate proceeds more rapidly in the supercooled liquid phase than in the solid phase. The effect is greater when supercooling is slow than when the process of supercooling is rapid. This phenomenon might be explained by the prearrangement of the monomer molecules without being fixed in the crystalline solid phase, such prearrangement being favorable from the viewpoint of polymerization. For monomers which polymerize near their melting point at a maximum rate, the presence of an even more ordered mesomorphous phase, similar to the liquid crystalline state, is assumed.