bluuebunny/crossref_metadata_2025_split huggingface dataset:
Core–Shell Composite as the Racemization Catalyst in the Dynamic Kinetic Resolution of Secondary Alcohols
Authors: Wang Jie , Do Dong‐Minh , Chuah Gaik‐Khuan , Jaenicke Stephan 
Published: November 2012

AbstractBeta–Silicalite‐1 core–shell microcomposites with controllable shell thickness were synthesized and used as racemization catalysts in the one‐pot dynamic kinetic resolution (DKR) of secondary alcohols by using lipase‐catalyzed transesterification. The inert Silicalite‐1 shell covered the external acidic sites of the Beta zeolite core, suppressing dehydration and non‐enantioselective transesterification of the alcohol. The alcohols could penetrate the Silicalite‐1 shell to access the acidic sites at the core Beta for racemization, however, the enzymatically formed (R)‐esters were excluded owing to their larger size. As a result, the high ee of the (R)‐ester products was conserved and dehydration side products were minimized. Owing to the shape selective nature of the composite racemization catalyst, small and readily available acyl donors could be used in the enzyme‐catalyzed transesterification to obtain the esters with high enantiopurity. The DKR of 1‐phenylethanol with isopropenyl acetate using an optimized core–shell catalyst, CS‐60, gave 92 % selectivity to ester formation and the desired (R)‐1‐phenylethyl acetate was formed with 94 % ee.
Application and Mechanistic Studies of a Water‐Oxidation Catalyst in Alcohol Oxidation by Employing Oxygen‐Transfer Reagents
Authors: Verho Oscar , Dilenstam Marléne D. V. , Kärkäs Markus D. , Johnston Eric V. , Åkermark Torbjörn , Bäckvall Jan‐E. , Åkermark Björn 
Published: November 2012

AbstractBy using a dimeric ruthenium complex in combination with tert‐butyl hydrogen peroxide (TBHP) as stoichiometric oxidant, a mild and efficient protocol for the oxidation of secondary benzylic alcohols was obtained, thereby giving the corresponding ketones in high yields within 4 h. However, in the oxidation of aliphatic alcohols, the TBHP protocol suffered from low conversions owing to a competing Ru‐catalyzed disproportionation of the oxidant. Gratifyingly, by switching to Oxone (2 KHSO5⋅KHSO4⋅K2SO4 triple salt) as stoichiometric oxidant, a more efficient and robust system was obtained that allowed for the oxidation of a wide range of aliphatic and benzylic secondary alcohols, giving the corresponding ketones in excellent yields. The mechanism for these reactions is believed to involve a high‐valent RuV–oxo species. We provide support for such an intermediate by means of mechanistic studies.
Gold(I)‐Catalyzed Divergence in the Preparation of Bicyclic Enol Esters: From Exclusively [3C+2C]‐Cycloaddition Reactions to Exclusive Formation of Vinylcyclopropanes
Authors: Conyers Ryan C. , Gung Benjamin W. 
Published: November 2012

AbstractWith the use of benzonitrile‐stabilized AuI catalyst [Au(IPr)(NCPh)]SbF6 (Ic; IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene), a spectrum of reactivity is observed for propargyl ester 4 a with cyclic vinyl ethers, ranging from exclusively [3C+2C] cycloaddition reactions to exclusively cyclopropanation depending only on the structure of the substrate. Some initially formed cyclopropanation products rearrange into the corresponding formally [3C+2C] cycloaddition products after treatment with fresh AuI complex at 80 °C. Vinylcyclopropanes formed from dihydrofuran and dihydropyran resisted such rearrangement, even in the presence of fresh AuI catalyst at elevated temperature. This study addresses an important mechanistic question concerning whether the five‐membered‐ring products were produced by a direct [3C+2C] cycloaddition reaction or by a sequential cyclopropanation/ring‐expansion reaction. A dual pathway is proposed for the AuI‐catalyzed reactions between propargyl esters and cyclic vinyl ethers. The different behavior among vinyl cyclic ethers is attributed to the difference in the polarization of the π bond. Highly polarized bonds appear to undergo the cycloaddition reaction whereas less polar π‐bonds produce cyclopropanes.
Synthesis and Quantitative Structure–Activity Relationships of Selective BCRP Inhibitors
Authors: Marighetti Federico , Steggemann Kerstin , Hanl Markus , Wiese Michael 
Published: November 2012

AbstractThe breast cancer resistance protein (BCRP/ABCG2) is a member of the ABC transporter superfamily. This protein has a number of physiological functions, including protection of the human body from xenobiotics. The overexpression of BCRP in certain tumor cell lines causes cross‐resistance against various drugs used in chemotherapeutic treatment. In a previous work we showed that a new class of compounds derived from XR9576 (tariquidar) selectively inhibits BCRP. In this work we synthesized more members of this class, with modification on the second and third aromatic rings. The inhibitory activities against BCRP and P‐gp were assayed using a Hoechst 33342 assay for BCRP and a calcein AM assay for P‐gp. Finally, quantitative structure–activity relationships for both aromatic rings were established. The results obtained show the importance of the electron density on the third aromatic ring, influenced by substituents, pointing to interactions with aromatic residues of the protein binding site. In the second aromatic ring the activity of compounds is influenced by the steric volume of the substituents.
Photocatalytic Removal of Soot: Unravelling of the Reaction Mechanism by EPR and in situ FTIR Spectroscopy
Authors: Smits Marianne , Ling Yun , Lenaerts Silvia , Van Doorslaer Sabine 
Published: November 2012

AbstractPhotocatalytic soot oxidation is studied on P25 TiO2 as an important model reaction for self‐cleaning processes by means of electron paramagnetic resonance (EPR) and Fourier transform infrared (FTIR) spectroscopy. Contacting of carbon black with P25 leads on the one hand to a reduction of the local dioxygen concentration in the powder. On the other hand, the weakly adsorbed radicals on the carbon particles are likely to act as alternative traps for the photogenerated conduction‐band electrons. We find furthermore that the presence of dioxygen and oxygen‐related radicals is vital for the photocatalytic soot degradation. The complete oxidation of soot to CO2 is evidenced by in situ FTIR spectroscopy, no intermediate CO is detected during the photocatalytic process.
Synthesis of Carbohydrates in a Continuous Flow Reactor by Immobilized Phosphatase and Aldolase
Authors: Babich Lara , Hartog Aloysius F. , van Hemert Lieke J. C. , Rutjes Floris P. J. T. , Wever Ron 
Published: November 2012

AbstractHerein, we report a new flow process with immobilized enzymes to synthesize complex chiral carbohydrate analogues from achiral inexpensive building blocks in a three‐step cascade reaction. The first reactor contained immobilized acid phosphatase, which phosphorylated dihydroxyacetone to dihydroxyacetone phosphate using pyrophosphate as the phosphate donor. The second flow reactor contained fructose‐1,6‐diphosphate aldolase (RAMA, rabbit muscle aldolase) or rhamnulose‐1‐phosphate aldolase (RhuA from Thermotoga maritima) and acid phosphatase. The immobilized aldolases coupled the formed dihydroxyacetone phosphate to aldehydes, resulting in phosphorylated carbohydrates. A final reactor containing acid phosphatase that dephosphorylated the phosphorylated product yielded the final product. Different aldehydes were used to synthesize carbohydrates on a gram scale. To demonstrate the feasibility of the flow systems, we synthesized 0.6 g of the D‐fagomine precursor. By using immobilized aldolase RhuA we were also able to obtain other stereoisomers of the D‐fagomine precursor.
Oxalic Amidines – Protonation Studies and Activity in Lactide Polymerisation
Authors: dos Santos Vieira Ines , Dietz Christina , Mohr Fabian , Beckert Rainer , Herres‐Pawlis Sonja 
Published: November 2012

AbstractThe oxalic amidine N,N′‐dimethyl‐N,N′‐diphenyl‐1,2‐bis[4‐tolylimino]ethane‐1,2‐diamine was used to synthesise a chloridozinc complex and two monoprotonated species either with chloride or triflate counterions. The compounds have been structurally characterised by X‐ray crystallography. Proton affinities have been determined by quantum chemical calculations to investigate why only the iminium protonated species is selectively formed upon mild protonation. To better understand the coordination properties of the ligand, different possible coordination modes of the ligand to zinc chloride have been investigated by DFT calculations. The chloridozinc complex was applied as a catalyst in the melt polymerisation of rac‐lactide and exhibited high activity combined with excellent agreement between the obtained and calculated molecular weights.
Polyglycerol‐Tagged Molecular Clips as Receptors in Protic Solvents
Authors: Zieringer Maximilian , Casas Cartagena Marçal , Burakowska Ewelina , Taktikos Johannes , Neuthe Katja , Bandmann Heinz , Klärner Frank‐Gerrit , Haag Rainer 
Published: November 2012

AbstractFour charge‐neutral molecular clips modified with polyglycerol (PG) dendrons of first and second generation and with hyperbranched polyglycerols (HPG) in the central unit as solubilizing units were synthesized. Their use as supramolecular hosts for the complexation of several guest molecules such as caffeine, N‐methylnicotinamide iodide, and Kosower salt was studied in methanol and water. Association constants and Gibbs enthalpies of association were determined by 1H NMR titration experiments. The obtained results were compared to the association behavior of molecular clips that carry anionic substituents. These results offer remarkable insights into the contribution of the substituents to host–guest binding and enable a strategy for improved substituent design.
Cycloaddition of 2‐Methyleneaziridines with Isocyanates Catalyzed by Tin Iodide
Authors: Takahashi Hiroki , Yasui Seiji , Tsunoi Shinji , Shibata Ikuya 
Published: November 2012

Abstract2‐Methyleneaziridines proved to be good substrates for the cycloaddition with isocyanates, for which a tin iodide system, Bu2SnI2–LiI, was employed as an effective catalyst. Products were derived from N‐attack of the ring‐opened metalloenamine intermediate.
Enzyme Based Amperometric Biosensor for Adenine Determination
Authors: Bóka Beáta , Adányi Nóra , Virág Diána , Frebort Ivo , Kiss Attila 
Published: November 2012

AbstractAn enzyme‐based amperometric biosensor was developed for the rapid determination of adenine in biological and food samples. Recombinant adenine deaminase (EC 3.5.4.2) from Schizosaccharomyces pombe was co‐immobilized on graphite electrode with xanthine oxidase (EC 1.17.3.2), peroxidase (EC 1.11.1.7) and an Os mediator. Optimal working conditions were pH 7.0 and −150 mV vs. Ag/AgCl. The novel method was characterized by a detection limit of 1 µM and a linear measuring range of 0.005–0.1 mM. Different beer and tea samples were analyzed by the newly elaborated adenine biosensor. The results obtained correlate with the adenine content measured by the reference HPLC method.
A method for tuning tuned mass dampers for seismic applications
Authors: Miranda Julio C. 
Published: November 2012

ABSTRACTThis paper studies tuned mass dampers (TMDs) resulting in high modal damping for mechanical systems incorporating such devices for the purpose of seismic response reduction. Focusing on the determination of damping and tuning, the proposed methodology identifies a point of multiplicity of complex eigenvalues and eigenvectors, resulting in different parameters for TMDs according to their location with respect to such multiplicity condition. It is shown that significant equal modal damping and average modal damping can be induced by properly tuning highly damped TMDs, obtaining parameters intrinsic to the mechanical systems, and excitation independent. Further, it is shown that the methodology yields, as particular cases, two proposals by others using TMDs for the same purpose of seismic response abatement. Copyright © 2012 John Wiley & Sons, Ltd.
Expression levels of neuroimmune biomarkers in hypothalamus of allergic mice after phthalate exposure
Authors: Win‐Shwe Tin‐Tin , Yanagisawa Rie , Koike Eiko , Nitta Hiroshi , Takano Hirohisa 
Published: November 2012

ABSTRACTPreviously, we demonstrated that maternal exposure to phthalates enhances atopic dermatitis in male mouse offspring. However, whether phthalate exposure affects neuroimmune biomarkers in allergic mice has not yet been studied. Di‐(2‐ethylhexyl) phthalate (DEHP) and di‐isononyl phthalate (DINP) are environmental chemicals that are commonly used as plasticizers. This study was designed to investigate the expression levels of neuroimmune biomarkers in the hypothalamus of a murine model of allergic asthma after phthalate exposure throughout juvenility until adulthood. Six‐week‐old C3H/HeJ Jcl male mice were treated with DEHP or DINP (0, 0.02, 0.4 or 8 nmol per body per week) and ovalbumin (OVA; 1 µg per body per 2 weeks) for 7 weeks intratracheally. On the day after the completion of the phthalate and OVA treatment, the hypothalamus from each mouse was collected, and the mRNA expression levels of neuroimmune biomarkers were examined using a real‐time RT‐PCR analysis. The mRNA expression levels of the proinflammatory cytokines interleukin (IL)‐1β and tumor necrosis factor (TNF)‐α, the chemokine CCL3, the transcription factor nuclear factor (NF)‐κB, the oxidative stress marker heme‐oxygenase (HO)1, a nerve growth factor, and the microglia marker Iba1 were remarkably up‐regulated in the hypothalami of mice treated with 8 nmol of DEHP in the presence of the allergen. However, no significant changes were observed, except for reductions in the TNF‐α and CCL2 mRNA levels, in mice exposed to DINP combined with the allergen. This study is the first report to show that high‐dose DEHP exposure throughout juvenility until adulthood may induce neuroinflammation by modulating neuroimmune biomarkers in the hypothalami of allergic mice. Copyright © 2012 John Wiley & Sons, Ltd.
Advance in research of microRNA in Caenorhabditis elegans
Authors: Liu Jing , Yang Baofeng , Ai Jing 
Published: November 2012

AbstractmicroRNA (miRNA) is a family of small, non‐coding RNA first discovered as an important regulator of development in Caenorhabditis elegans (C. elegans). Numerous miRNAs have been found in C. elegans, and some of them are well conserved in many organisms. Though, the biologic function of miRNAs in C. elegans was largely unknown, more and more studies support the idea that miRNA is an important molecular for C. elegans. In this review, we revisit the research progress of miRNAs in C. elegans related with development, aging, cancer, and neurodegenerative diseases and compared the function of miRNAs between C. elegans and human. J. Cell. Biochem. 114: 994–1000, 2013. © 2012 Wiley Periodicals, Inc.
Initial experience of 3 tesla apparent diffusion coefficient values in differentiating benign and malignant thyroid nodules
Authors: Ilica A. Turan , Artaş Hakan , Ayan Asli , Günal Armağan , Emer Ozdes , Kilbas Zafer , Meric Coskun , Atasoy Mehmet Mahir , Uzuner Ovsev 
Published: November 2012

AbstractPurpose:To evaluate the role of diffusion‐weighted magnetic resonance imaging (DWMRI) in differentiating benign and malignant thyroid nodules using a 3 Tesla (T) MRI scanner.Materials and Methods:Twenty‐eight nodules in 25 patients and 14 healthy control cases were included in the study. DWMRI was acquired with 6 b values with a 3T MRI scanner. The apparent diffusion coefficient (ADC) values of the nodules were calculated from reconstructed ADC map images and were compared with the final histopathological diagnoses.Results:The mean ADC value of the benign nodules was 1548 ± 353.4 (×10−6 mm2/s), and the mean ADC of the malignant nodules was 814 ± 177.12 (×10−6 mm2/s). The normal thyroid tissue had a mean ADC value of 1323.43 ± 210.35 × 10−6 mm2/s (958–1689 × 10−6 mm2/s) in the healthy control group. The ADC values were significantly different among the three groups (P = 0.001). An ADC value of 905 × 10−6 mm2/s was determined to be the cutoff value for differentiating benign and malignant nodules, with 90% (55.5–98.3) sensitivity and 100% (81.3–100.0) specificity.Conclusion:This study suggests that the ADC values of nodules measured with a 3T MRI scanner could help in differentiating benign thyroid nodules from malignant nodules. J. Magn. Reson. Imaging 2013;37:1077–1082. © 2012 Wiley Periodicals, Inc.
Short TE 7Li‐MRS confirms Bi‐exponential lithium T2 relaxation in humans and clearly delineates two patient subtypes
Authors: Port John D. , Rampton Karen E. , Shu Yunhong , Manduca Armando , Frye Mark A. 
Published: November 2012

AbstractPurpose:(i) To develop an MRS technique to measure 7Li levels in human brain in a reasonable scan time, (ii) to develop a technique to quantify 7Li T2 relaxation times as measured from human brain in patients taking lithium for the treatment of their bipolar disorder, and (iii) to confirm or refute the presence of bi‐exponential 7Li T2 relaxation in human brain.Materials and Methods:We modified a spin‐echo MRS pulse sequence to decrease its minimum echo time. With IRB approval, we performed lithium MRS with the modified pulse sequence on 13 euthymic bipolar patients stable on long‐term lithium to treat their disease.Results:We were able to achieve a total scan time per sample of 8:20; total scan time including imaging, calibration and MRS was approximately 1 h 15 min. We observed bi‐exponential T2 relaxation in the majority of patients, with an average short decay time of 5.3 ± 1.4 ms and an average long decay time of 68.2 ± 10.2 ms. However, in two patients we observed strongly mono‐exponential T2 relaxation with an average decay time of 47.4 ± 1.3 ms.Conclusion:7Li relaxation patterns may prove useful to distinguish between lithium‐responsive and lithium nonresponsive bipolar patients. J. Magn. Reson. Imaging 2013;37:1451–1459. © 2012 Wiley Periodicals, Inc.
Hungry for Growth? Small and Medium‐sized Tourism Enterprise (SMTE) Business Ambitions, Knowledge Acquisition and Industry Engagement
Authors: King Brian Edward , Breen John , Whitelaw Paul A. 
Published: November 2012

ABSTRACTDifferences are identified between the preferred information and learning channels of small and medium‐sized tourism enterprise (SMTE) proprietors, who have an interest in business operations (growers) or who have relatively less interest (lifestylers). Lifestylers sign up frequently to tourism industry associations, whereas growers have a tendency to join generic business groupings. The most common information for both groups is marketing related, and intensive use is made of online information to support day‐to‐day business operations. In aggregate, SMTE proprietors are avid information seekers, attaching importance to the advice provided from experienced and trusted sources. Growers proactively gather information about general management as well as tourism‐specific knowledge. Adopting a ‘one size fits all’ approach to providing information for the SMTE sector is unlikely to be effective. Copyright © 2012 John Wiley & Sons, Ltd.
Tandem mass spectrometry for characterization of covalent adducts of DNA with anticancer therapeutics
Authors: Silvestri Catherine , Brodbelt Jennifer S. 
Published: November 2012

AbstractThe chemotherapeutic activities of many anticancer and antibacterial drugs arise from their interactions with nucleic acid substrates. Some of these ligands interact with DNA in a way that causes conformational changes or damage to the nucleic acid targets, ultimately altering recognition by key DNA‐specific enzymes, interfering with DNA transcription or prohibiting replication, and terminating cell growth and proliferation. The design and synthesis of ligands that bind to nucleic acids remains a dynamic field in medicinal chemistry and pharmaceutical research. The quest for more selective and efficacious DNA‐interactive anticancer chemotherapeutics has likewise catalyzed the need for sensitive analytical methods that can provide structural information about the nature of the resulting DNA adducts and provide insight into the mechanistic pathways of the DNA/drug interactions and the impact on the cellular processes in biological systems. This review focuses on the array of tandem mass spectrometric strategies developed and applied for characterization of covalent adducts formed between DNA and anticancer ligands. © 2012 Wiley Periodicals, Inc., Mass Spec Rev 32:247–266, 2013
Diagnostic validity across racial and ethnic groups in the assessment of adolescent DSM‐IV disorders
Authors: Green Jennifer Greif , Gruber Michael J. , Kessler Ronald C. , Lin Julia Y. , Mclaughlin Katie A. , Sampson Nancy A. , Zaslavsky Alan M. , Alegria Margarita 
Published: November 2012

AbstractWe examine differential validity of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM‐IV) diagnoses assessed by the fully‐structured Composite International Diagnostic Interview Version 3.0 (CIDI) among Latino, non‐Latino Black, and non‐Latino White adolescents in comparison to gold standard diagnoses derived from the Schedule for Affective Disorders and Schizophrenia for School‐age Children (K‐SADS). Results are based on the National Comorbidity Survey Replication Adolescent Supplement, a national US survey of adolescent mental health. Clinicians re‐interviewed 347 adolescent/parent dyads with the K‐SADS. Sensitivity and/or specificity of CIDI diagnoses varied significantly by ethnicity/race for four of ten disorders. Modifications to algorithms sometimes reduced bias in prevalence estimates, but at the cost of reducing individual‐level concordance. These findings document the importance of assessing fully‐structured diagnostic instruments for differential accuracy in ethnic/racial subgroups. Copyright © 2012 John Wiley & Sons, Ltd.
The diverse functions of germline P‐granules in Caenorhabditis elegans
Authors: Voronina Ekaterina 
Published: November 2012

AbstractP‐granules are conserved cytoplasmic organelles, similar to nuage, that are present in Caenorhabditis elegans germ cells. Based on the prevailing sterility phenotype of the component mutants, P‐granules have been seen as regulators of germ cell development and function. Yet, specific germline defects resulting from P‐granule failure vary, depending on which component(s) are inactivated, at which stage of development, as well as on the presence of stress factors during animal culture. This review discusses the unifying themes in many P‐granule functions, with the main focus on their role as organizing centers nucleating RNA regulation in the germ cell cytoplasm. Mol. Reprod. Dev. 80:624–631, 2013. © 2012 Wiley Periodicals, Inc.