bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and reactions of pyrido[3,2,1‐jk]carbazole‐4,6‐diones
Authors: Stadlbauer Wolfgang , Dang Hoai Van , Knobloch Bernd 
Published: May 2011

AbstractPyrido[3,2,1‐jk]carbazoles 1, synthesized from carbazoles and alkyl‐ or arylmalonates, gave regioselective electrophilic substitution reactions at position 5 such as chlorination to 5‐chloro derivatives 2, nitration to 5‐nitro compounds 3, or hydroxylation to 5‐hydroxy derivatives 4. 5‐Hydroxy compounds 4 gave on treatment with strong bases ring contraction to 5, 6 or the ring opening product 7. Exchange of the chloro group in 2 with azide or amines gave the corresponding azides 8 and the 5‐amino derivatives 9 and 10. Alkylation of 1 with benzyl chloride or allyl bromide resulted in the formation of 5‐C‐alkylated products 11 together with 4‐alkyloxy derivatives 12. J. Heterocyclic Chem., 48, 1039 (2011).
Synthesis of novel spiro(indolone‐3,2′‐[1,3,4]thiadiazol)‐2‐ones and evaluation of their antidepressant and anticonvulsant activities
Authors: Hassan Alaa A. , Abdel‐Latif Fathy F. , El‐Din Ahmed M. Nour , Abdel‐Aziz Mohamed , Mostafa Sara M. , Bräse Stefan 
Published: May 2011

AbstractThe reaction of 3‐(dicyanomethylene)‐2‐indolone in a solution of ethanol/piperidine with 4‐substituted thiosemicarbazides forms the derivatives of 5′‐(substituted amino)‐3′H–spiro(indoline‐3,2′‐[1,3,4]thiadiazol‐2‐one. Rationales for these conversions involving the nucleophilic addition on the dicyanomethylene carbon atom are presented. The prepared compounds were evaluated each for antidepressant activity using tail suspension behavioral despair test and anticonvulsant activity against pentylenetetrazol induced seizures in mice. J. Heterocyclic Chem., (2011).
Chronological framework for the deglaciation of the Lake Michigan lobe of the Laurentide Ice Sheet from ice‐walled lake deposits
Authors: Curry Brandon , Petras Justine 
Published: May 2011

AbstractA revised chronological framework for the deglaciation of the Lake Michigan lobe of the south‐central Laurentide Ice Sheet is presented based on radiocarbon ages of plant macrofossils archived in the sediments of low‐relief ice‐walled lakes. We analyze the precision and accuracy of 15 AMS 14C ages of plant macrofossils obtained from a single ice‐walled lake deposit. The semi‐circular basin is about 0.72 km wide and formed of a 4‐ to 16‐m‐thick succession of loess and lacustrine sediment inset into till. The assayed material was leaves, buds and stems of Salix herbacea (snowbed willow). The pooled mean of three ages from the basal lag facies was 18 270 ± 50 14C a BP (21 810 cal. a BP), an age that approximates the switch from active ice to stagnating conditions. The pooled mean of four ages for the youngest fossil‐bearing horizon was 17 770 ± 40 14C a BP (21 180 cal. a BP). Material yielding the oldest and youngest ages may be obtained from sediment cores located at any place within the landform. Based on the estimated settling times of overlying barren, rhythmically bedded sand and silt, the lacustrine environment persisted for about 50 more years. At a 67% confidence level, the dated part of the ice‐walled lake succession persisted for between 210 and 860 cal. a (modal value: 610 cal. a). The deglacial age of five moraines or morainal complexes formed by the fluctuating margin of the Lake Michigan lobe have been assessed using this method. There is no overlap of time intervals documenting when ice‐walled lakes persisted on these landforms. The rapid readvances of the lobe during deglaciation after the last glacial maximum probably occurred at some point between the periods of ice‐walled lake sedimentation. Copyright © 2011 John Wiley & Sons, Ltd.
Relationships between primary productivity and bottom‐water oxygenation off northwest Africa during the last deglaciation
Authors: Filipsson Helena L. , Romero Oscar E. , Stuut Jan‐Berend W. , Donner Barbara 
Published: May 2011

AbstractThe upwelling region off northwest Africa is one of the most productive regions in the world ocean. This study details the response of surface‐ and deep‐water environments off Mauritania, northwest Africa, to the rapid climate events of the last deglaciation, especially the Bølling–Allerød (15.5–13.5 ka BP) and Younger Dryas (13.5–11.5 ka BP). A high accumulation rate gravity core GeoB7926‐2, recovered at ∼20° N, 18° W, was analysed for the grain size distribution of the terrigenous sediment fraction, the organic carbon content, diatom and benthic foraminifera communities. Humid conditions were observed during the Bølling–Allerød with a high contribution of fluvial sediment input. During the Younger Dryas intensified trade winds caused a larger sediment input of aeolian dust from the Sahara and more intense upwelling with higher primary productivity, as indicated by high diatom concentrations. The abrupt and large increase of organic matter caused low oxygen conditions at the sea floor, reflected by the poor benthic foraminiferal fauna and the dominance of the low‐oxygen‐tolerant foraminiferal species Bulimina exilis. This is surprising since low‐oxygen conditions have not been recorded during modern times at the sea floor in this region, despite present‐day intensive upwelling and high primary productivity. After the Younger Dryas, more humid conditions returned, diatom abundance decreased and B. exilis was replaced by typical deep‐sea species as found in the region today, indicating the return of more oxygenated conditions at the sea floor. Copyright © 2011 John Wiley & Sons, Ltd.
Microwave‐accelerated derivatization prior to GC‐MS determination of sex hormones
Authors: Xu Xu , Zhao Xin , Zhang Yupu , Li Dan , Su Rui , Yang Qiuling , Li Xueyuan , Zhang Huihui , Zhang Hanqi , Wang Ziming 
Published: May 2011

AbstractA new microwave‐accelerated derivatization method was developed for rapid determination of 13 natural sex hormones in feeds. Sex hormones were isolated from the sample matrix by ultrasonic extraction, followed by solid‐phase extraction, derivatized under microwave irradiation, and then analyzed directly by gas chromatography‐mass spectrometry (GC‐MS) in selective ion monitoring (SIM) mode. The key parameters affecting derivatization efficiency, including microwave irradiation time, microwave power, and reaction solvent were studied. Under microwave power of 360 W and microwave irradiation for 3 min, 13 natural sex hormones were simultaneously derivatized using heptafluorobutyric acid anhydride (HFBA) as derivatization reagent. This method was applied to the determination of 13 natural sex hormones in different feed samples, and the obtained results were compared with those obtained by the traditional thermal derivatization. The recoveries from 58.1 to 111% were obtained at sex hormone concentrations of 10–300 μg/kg with RSDs ≤12.0%. The results showed that the proposed method was fast, simple, efficient and can be applied to the determination of 13 natural sex hormones in different feed samples.
Automated pre‐column derivatization of thiolic fruit‐antibrowning agents by sequential injection coupled to high‐performance liquid chromatography using a monolithic stationary phase and an in‐loop stopped‐flow approach
Authors: Karakosta Theano D. , Tzanavaras Paraskevas D. , Themelis Demetrius G. 
Published: May 2011

AbstractThe present study reports the very first application of ethyl propiolate (EP) as an advantageous pre‐column derivatization reagent for the determination of thiols by liquid chromatography (LC). Cysteine (CYS), glutathione (GSH) and N‐acetylcysteine (NAC) were derivatized online under stopped‐flow conditions in a sequential injection (SI) system coupled to HPLC. The formed derivatives were separated isocratically with a monolithic stationary phase (100×4.6 mm id) and UV detected at 285 nm. Critical parameters that affected the online pre‐column derivatization reaction (e.g. the reaction time and the amount concentration of EP) and the separation (e.g. pH and the composition of the mobile phase) were investigated. The developed analytical scheme offers a total analysis time of less than 10 min, limits of detection in the range of 0.24–0.35 μmol/L and satisfactory linearity up to 200 μmol/L for all analytes. The proposed method was applied to the analysis of the selected thiols – that are often employed as antibrowning agents – in fresh fruit samples.
Optimization of the synthesis of a hyper‐crosslinked stationary phases: A new generation of highly efficient, acid‐stable hyper‐crosslinked materials for HPLC
Authors: Zhang Yu , Huang Yuming , Carr Peter W. 
Published: May 2011

AbstractA new family of hyper‐crosslinked (HC) phases was recently developed for use under very aggressive conditions including those encountered in ultra‐fast, high‐temperature two‐dimensional liquid chromatography (2‐DLC). This type of stationary phase has improved acid stability compared with the most acid‐stable, commercial RPLC phases. Kinetic studies are here reported that allow optimization of reaction time and crosslinking reagent concentrations used to prepare such HC phases. We have determined that the Friedel‐Crafts chemistry used to prepare HC phases is nearly complete within about 15 min. Thus, reaction time for each step of the synthesis was greatly reduced from the multihour reactions used previously without sacrificing the stationary phases' acid stability and separation performance. Results from elemental analysis of the finished particles were combined with LC data to provide insights regarding the properties of these HC phases. This new generation of acid stable HC phases, with their attractive chromatographic properties, should be very useful in the separations of bases or biological analytes in acidic media, especially at elevated temperatures.
Multiple‐point hit distribution functions and vague convergence of related measures
Authors: Ballani Felix 
Published: May 2011

AbstractFor a stationary and isotropic random closed set Z in \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\mathbb {R}^d$\end{document} it is a well‐known fact that its covariance C(t) and its spherical contact distribution function \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\widetilde{H}_s(t)$\end{document} admit at t = 0 a derivative which is a multiple of the surface intensity of Z. Within the quite general setting of gentle sets, Kiderlen and Rataj 10 show a more general result (covering both previous cases) for the derivative of a hit distribution function of Z with respect to a structuring element which only needs to be compact and contains the origin. Using this general setting the present paper introduces m‐point hit distribution functions of Z, m ⩾ 2, and shows how they are related to the mth‐order surface product density of Z. This also generalizes a result of Ballani 1 for the two‐point spherical contact distribution function of a germ‐grain model. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
Large deviations for discontinuous additive functionals of symmetric stable processes
Authors: Takeda Masayoshi , Tsuchida Kaneharu 
Published: May 2011

AbstractLet Xt be a symmetric stable process on d‐dimensional Euclidean space \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}${\mathbb {R}}^d$\end{document}. Let F(x, y) be a symmetric positive bounded function on \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}${\mathbb {R}}^d\times {\mathbb {R}}^d$\end{document} vanishing on the diagonal set and define a discontinuous additive functional by At(F) = ∑0 < s ⩽ tF(Xs −, Xs). We establish the large deviation principle of At(F)/t by employing the Gärtner‐Ellis theorem. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
Rational cuspidal curve with a Galois point
Authors: Yoshihara Hisao 
Published: May 2011

AbstractFor a rational cuspidal curve C we study if it has a Galois point. The result is as follows: if C has an outer Galois point, then C is projectively equivalent to the curve defined by xe = yn where (e, n) = 1. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
Amphiphilic Diblock Copolymer with Dithienylethene Pendants: Synthesis and Photo‐Modulated Self‐Assembly
Authors: Chen Zhen , He Yaning , Wang Yang , Wang Xiaogong 
Published: May 2011

AbstractIn this work, an amphiphilic diblock copolymer (PEG43‐b‐PSDTE29) bearing photochromic dithienylethene (DTE) pendants is synthesized by reversible addition fragmentation chain transfer radical polymerization. The diblock copolymer was characterized by spectroscopic methods and gel permeation chromatography. The analyses proved the well‐defined structure and narrow molecular weight distribution of the diblock copolymer. The DTE pendants could undergo reversible photoisomerization between their open and closed forms in solution when irradiated with UV and visible light as indicated by 1H NMR and UV‐vis spectroscopy. Hollow vesicle‐like structures were formed by gradually adding deionized water to the colorless PEG43‐b‐PSDTE29open (DTE in open form) tetrahydrofuran solution. Under the same conditions, the aggregates formed in the blue PEG43‐b‐PSDTE29close (DTE in closed form) solution were colloidal spheres with solid interiors. The isomerization of DTE pendants could cause the deformation of the vesicle‐like structures. The above results demonstrate a kind of novel photo‐modulated self‐assembly behavior of the amphiphilic diblock copolymer, which could be used for drug‐delivery and other applications. magnified image
Influence of the metabolic syndrome on leptin and leptin receptor in breast cancer
Authors: Carroll Paul A. , Healy Laura , Lysaght Joanne , Boyle Terry , Reynolds John V. , Kennedy M. John , Pidgeon Graham , Connolly Elizabeth M. 
Published: May 2011

AbstractObesity and its associated metabolic syndrome (MetS) are recognized risk factors for breast cancer. The molecular basis for this association remains largely unknown. Adipokines, in particular leptin and adiponectin, are thought to form part of the mechanism linking obesity with cancer through their altered expression/production either systemically (endocrine pathway) or locally (paracrine/autocrine pathway). Using quantitative PCR, mRNA expression of adiponectin (AdipoQ) and leptin (Ob) in mammary adipose tissue (MAT), intratumoral leptin and associated ligand receptors (ObR, AdipoR1, and AdipoR2) was examined in 77 patients with complete anthropomorphic and serological data. Expression of Ob in MAT, and ObR in matched tumor tissue was significantly higher in patients with MetS compared to obese only or normal weight cancer patients (P < 0.005). There was no difference in intratumoral leptin adiponectin or its ligand receptors in the same groups. Individual features of MetS correlated with Ob and ObR expression, but not obesity markers (BMI, waist circumference). mRNA expression of leptin (Ob) and ObR, in adipose tissue and matched tumor samples, respectively, appear to be associated with obesity status in breast cancer. Increasing insulin resistance is a predominant feature of this higher Ob/ObR expression observed. These novel data indicate that the MetS may be an amenable risk factor for breast cancer. © 2011 Wiley‐Liss, Inc.
Identification and localization of the sperm CRISP family protein CiUrabin involved in gamete interaction in the ascidian Ciona intestinalis
Authors: Yamaguchi Akira , Saito Takako , Yamada Lixy , Taniguchi Hisaaki , Harada Yoshito , Sawada Hitoshi 
Published: May 2011

AbstractAscidians are hermaphrodites, and most release sperm and eggs nearly simultaneously. Many species, including Halocynthia roretzi and Ciona intestinalis, are self‐sterile. We previously reported that the interaction between a 12 EGF‐like repeat‐containing vitelline‐coat (VC) protein, HrVC70, and a sperm GPI‐anchored CRISP, HrUrabin, in lipid rafts plays a key role in self‐/nonself‐recognizable gamete interaction in H. roretzi. On the other hand, we recently identified two pairs of polymorphic genes responsible for self‐incompatibility in C. intestinalis by positional cloning: The sperm polycystin 1‐like receptors s‐Themis‐A/B and its fibrinogen‐like ligand v‐Themis‐A/B on the VC. However, it is not known if the orthologs of HrVC70 and HrUrabin also participate in gamete interaction in C. intestinalis since they are from different orders. Here, we tested for a C. intestinalis ortholog (CiUrabin) of HrUrabin by searching the genome database and proteomes of sperm lipid rafts. The identified CiUrabin belongs to the CRISP family, with a PR domain and a GPI‐anchor‐attachment site. CiUrabin appears to be specifically expressed in the testis and localized at the surface of the sperm head, as revealed by Northern blotting and immunocytochemistry, respectively. The specific interaction between CiVC57, a C. intestinalis ortholog of HrVC70, and CiUrabin was confirmed by Far Western analysis, similarly to the interaction between HrVC70 and HrUrabin. The molecular interaction between CiVC57 and CiUrabin may be involved in the primary binding of sperm to the VC prior to the allorecognition process, mediated by v‐Themis‐A/B and s‐Themis‐A/B, during fertilization of C. intestinalis. Mol. Reprod. Dev. 78:488–497, 2011. © 2011 Wiley‐Liss, Inc.
Two‐dimensional phase correction method for single and multi‐shot echo planar imaging
Authors: Zur Yuval 
Published: May 2011

AbstractGhost artifacts are a serious issue in single and multi‐shot echo planar imaging. Because of these coherent artifacts, it is essential to consistently suppress the ghosts. In this article, we present a phase correction algorithm that achieves excellent ghost suppression for single and multi‐shot echo planar imaging. The phase correction is performed along both the x (read) direction and y (phase) direction. To this end, we apply a double field of view prescan and compute the phase required for ghost suppression. This phase is fitted to a 2D polynomial. The fitted phase is used to correct the echo planar imaging images. The correction algorithm can be used with any readout gradient polarities and any number of shots. A flow chart of the correction method is provided to better clarify the full process. Finally, phantom and volunteer images demonstrate the improvement of artifact suppression obtained with this algorithm over conventional phase correction methods. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.
Magnetic and relaxation properties of multifunctional polymer‐based nanostructured bioferrofluids as MRI contrast agents
Authors: Amiri Houshang , Bustamante Rodney , Millán Angel , Silva Nuno J.O. , Piñol Rafael , Gabilondo Lierni , Palacio Fernando , Arosio Paolo , Corti Maurizio , Lascialfari Alessandro 
Published: May 2011

AbstractA series of maghemite/polymer composite ferrofluids with variable magnetic core size, which show a good efficiency as MRI contrast agents, are presented. These ferrofluids are biocompatible and can be proposed as possible platforms for multifunctional biomedical applications, as they contain anchoring groups for biofunctionalization, can incorporate fluorescent dyes, and have shown low cellular toxicity. The magnetic properties of the ferrofluids have been determined by means of magnetization and ac susceptibility measurements as a function of temperature and frequency. The NMR dispersion profiles show that the low frequency behavior of the longitudinal relaxivity r1 is well described by the heuristic model of 1H nuclear relaxation induced by superparamagnetic nanoparticles proposed by Roch and co‐workers. The contrast efficiency parameter, i.e., the nuclear transverse relaxivity r2, for samples with d > 10 nm assumes values comparable with or better than the ones of commercial samples, the best results obtained in particles with the biggest magnetic core, d = 15 nm. The contrast efficiency results are confirmed by in vitro MRI experiments at ν = 8.5 MHz, thus allowing us to propose a set of optimal microstructural parameters for multifunctional ferrofluids to be used in MRI medical diagnosis. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.
A flexible 32‐channel receive array combined with a homogeneous transmit coil for human lung imaging with hyperpolarized 3He at 1.5 T
Authors: Deppe Martin H. , Parra‐Robles Juan , Marshall Helen , Lanz Titus , Wild Jim M. 
Published: May 2011

AbstractParallel imaging presents a promising approach for MRI of hyperpolarized nuclei, as the penalty in signal‐to‐noise ratio typically encountered with 1H MRI due to a reduction in acquisition time can be offset by an increase in flip angle. The signal‐to‐noise ratio of hyperpolarized MRI generally exhibits a strong dependence on flip angle, which makes a homogeneous B1+ transmit field desirable. This paper presents a flexible 32‐channel receive array for 3He human lung imaging at 1.5T designed for insertion into an asymmetric birdcage transmit coil. While the 32‐channel array allows parallel imaging at high acceleration factors, the birdcage transmit coil provides a homogeneous B1+ field. Decoupling between array elements is achieved by using a concentric shielding approach together with preamplifier decoupling. Coupling between transmit coil and array elements is low by virtue of a low geometric coupling coefficient, which is reduced further by the concentric shields in the array. The combination of the 32‐channel array and birdcage transmit coil provides 3He ventilation images of excellent quality with similar signal‐to‐noise ratio at acceleration factors R = 2 and R = 4, while maintaining a homogeneous B1+. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.
Origins of the ultrashort‐T21H NMR signals in myelinated nerve: A direct measure of myelin content?
Authors: Horch R. Adam , Gore John C. , Does Mark D. 
Published: May 2011

AbstractRecently developed MRI techniques have enabled clinical imaging of short‐lived 1H NMR signals with T2 < 1 ms. Using these techniques, novel signal enhancement has been observed in myelinated tissues, although the source of this enhancement has not been identified. Herein, we report studies of the nature and origins of ultrashort T2 (uT2) signals (50 μs < T2 < 1 ms) from amphibian and mammalian myelinated nerves. NMR measurements and comparisons with myelin phantoms and expected myelin components indicate that these uT2 signals arise predominantly from methylene 1H on/in the myelin membranes, which suggests that direct measurement of uT2 signals can be used as a new means for quantitative myelin mapping. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Estimation of liver T*2 in transfusion‐related iron overload in patients with weighted least squares T*2 IDEAL
Authors: Vasanawala Shreyas S. , Yu Huanzhou , Shimakawa Ann , Jeng Michael , Brittain Jean H. 
Published: May 2011

AbstractMRI imaging of hepatic iron overload can be achieved by estimating T2* values using multiple‐echo sequences. The purpose of this work is to develop and clinically evaluate a weighted least squares algorithm based on T2* Iterative Decomposition of water and fat with Echo Asymmetry and Least‐squares estimation (IDEAL) technique for volumetric estimation of hepatic T2* in the setting of iron overload. The weighted least squares T2* IDEAL technique improves T2* estimation by automatically decreasing the impact of later, noise‐dominated echoes. The technique was evaluated in 37 patients with iron overload. Each patient underwent (i) a standard 2D multiple‐echo gradient echo sequence for T2* assessment with nonlinear exponential fitting, and (ii) a 3D T2* IDEAL technique, with and without a weighted least squares fit. Regression and Bland–Altman analysis demonstrated strong correlation between conventional 2D and T2* IDEAL estimation. In cases of severe iron overload, T2* IDEAL without weighted least squares reconstruction resulted in a relative overestimation of T2* compared with weighted least squares. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.