bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Substrate Spectrum of the Inverting sec‐Alkylsulfatase Pisa1
Authors: Schober Markus , Knaus Tanja , Toesch Michael , Macheroux Peter , Wagner Ulrike , Faber Kurt 
Published: June 2012

AbstractThe substrate spectrum of the inverting alkylsulfatase Pisa1 was investigated using a range of sec‐alkyl sulfate esters bearing aromatic, olefinic and acetylenic moieties. Perfect enantioselectivities were obtained for substrates bearing groups of different size adjacent to the sulfate ester moiety. Insufficient selectivities could be doubled by using dimethyl sulfoxide (DMSO) as co‐solvent. Hydrolytically unstable benzylic sulfate esters could be sufficiently stabilised by introduction of electron‐withdrawing substituents. Overall, Pisa1 appears to be a very useful inverting alkylsulfatase for the deracemisation of rac‐sec‐alcohols via enzymatic hydrolysis of their corresponding sulfate esters, which furnishes homochiral products possessing the ‘anti‐Kazlauskas’ configuration.
Catalytic Asymmetric Epoxidation of 2‐Cyclopentenones
Authors: Lee Anna , Reisinger Corinna M. , List Benjamin 
Published: June 2012

AbstractThe first highly efficient asymmetric epoxidation of 2‐cyclopentenones has been developed. Using a newly designed and readily available Cinchona amine catalyst, 2‐cyclopentenones are reacted with hydrogen peroxide to give the corresponding epoxycyclopentanones in high yields and excellent enantioselectivities.
Transition Metal‐Free Stereoselective α‐Vinylation of Cyclic Ketones with Arylacetylenes in the Superbasic Catalytic Triad Potassium Hydroxide/tert‐Butyl Alcohol/Dimethyl Sulfoxide
Authors: Trofimov Boris A. , Schmidt Elena Yu. , Zorina Nadezhda V. , Ivanova Elena V. , Ushakov Igor' A. , Mikhaleva Al'bina I. 
Published: June 2012

AbstractA stereoselective α‐vinylation of cycloaliphatic ketones with arylacetylenes under the transition metal‐free conditions has been developed. The reaction is promoted by the superbasic catalytic triad potassium hydroxide/tert‐butyl alcohol/dimethyl sulfoxide (80–110 °C, 1–2 h) to afford mainly (E)‐β,γ‐ethylenic ketones, their (E)‐α,β‐isomers being minor products, in up to 83% total yield.
A Scalable, Efficient Gold‐Catalyzed Oxidative Phosphonation of sp3 CH Bonds using Air as Sustainable Oxidant
Authors: Xie Jin , Li Huamin , Xue Qicai , Cheng Yixiang , Zhu Chengjian 
Published: June 2012

AbstractA scalable, efficient gold‐catalyzed oxidative phosphonation of sp3 CH bonds with various diarylphosphine oxides and dialkyl phosphites has been developed by using air as a sustainable oxidant under mild reaction conditions. It provides an easy access to α‐amino phosphonic compounds in high yields with a broad reaction scope. The safe, convenient and environmentally benign process makes this protocol very promising.
Effects of common agricultural tasks on measures of hearing loss
Authors: Humann Michael J. , Sanderson Wayne T. , Gerr Fred , Kelly Kevin M. , Merchant James A. 
Published: June 2012

AbstractBackgroundAmong agricultural populations, hearing loss caused by excessive noise exposure is common. However, examinations of associations between exposure to agricultural tasks and hearing loss are limited.MethodsAudiometry and lifetime exposure to 11 agricultural tasks were analyzed among 1,568 participants. Gender stratified multivariable linear regression was used to estimate associations between exposure duration and three hearing loss metrics.ResultsAmong men, significant associations were observed between hearing loss and hunting or target shooting, all‐terrain vehicle (ATV) or motorcycle riding, chain saw use, electric or pneumatic tool use, living on a farm, and all agricultural tasks combined. When all significant exposure metrics were included in a single model, associations remained for hunting or target shooting, electric or pneumatic tool use and living on a farm. Significant associations were sparse among women, and in all cases paradoxical.ConclusionsDespite imprecise estimation of noise exposure, specific agricultural tasks were associated with hearing loss. Am. J. Ind. Med. 55:904–916, 2012. © 2012 Wiley Periodicals, Inc.
Sulfonated multiwalled carbon nanotube/sulfonated poly(ether sulfone) composite membrane with low methanol permeability for direct methanol fuel cells
Authors: Yun Sungjin , Heo Yusun , Im Hyungu , Kim Jooheon 
Published: June 2012

AbstractAn organic/inorganic composite membrane was prepared based on sulfonated poly(ether sulfone) (s‐PES) embedded with sulfonated multiwalled carbon nanotubes (s‐MWNTs). The ion exchange capacity (IEC), proton conductivity, and water uptake of the SPES membranes increased with increasing s‐MWNTs content. The increased water uptake was attributed to hydrogen bond formation between the carbonyl group of the s‐MWNTs and a water molecule. The composite membranes exhibited proton conductivities ranging from 3.9281 × 10−4 to 7.0788 × 10−3 S/cm at 80°C, as well as low methanol permeability ranging from 4.4405 × 10−10 to 9.1008 × 10−10 cm2 s−1 at 25°C. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
High‐contrast, high‐sensitivity aqueous base‐developable polynorbornene dielectric
Authors: Raeis‐Zadeh Mehrsa , Kohl Paul A. 
Published: June 2012

AbstractThe impact of multifunctional epoxy‐based additives on the crosslinking, photolithographic properties, and adhesion properties of a tetramethyl ammonium hydroxide developable, polynorbornene (PNB)‐based dielectric was investigated. Three different multifunctional epoxy additives were investigated: di‐functional, tri‐functional, and tetra‐functional epoxy compounds. The tetra‐functional epoxy crosslinker enhanced the UV absorbing properties of the polymer at 365 nm wavelength. It was found that the epoxy photo‐catalyst could be efficiently activated without a photosensitizer when the tetra‐functional epoxy was used. The polymer mixture with additional (3 wt %) tetra‐functional epoxy crosslinker and without a UV sensitizer showed improved sensitivity by a factor of 4.7 as compared to a polymer mixture containing the same number of equivalents of non‐UV sensitive epoxy with a UV sensitizer. The contrast improved from 7.4 for the polymer mixture with non‐UV absorbing epoxy and a UV sensitizer to 33.4 for the new formulation with 3 wt % tetra‐functional epoxy and no UV sensitizer. The addition of the tetra‐functional epoxy crosslinker also improved the polymer‐to‐substrate adhesion, which permitted longer development times, and allowed the fabrication of high‐aspect‐ratio structures. Hollow‐core pillars were fabricated in 96‐µm thick polymer films with a depth‐to‐width aspect‐ratio of 14 : 1. The degree of crosslinking in the cured films was studied by nanoindentation and swelling measurements. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Kinetics of thermodegradation of palm kernel oil derived medium‐chain‐length polyhydroxyalkanoates
Authors: Sin Mei Chan , Tan Irene Kit Ping , Annuar Mohd Suffian Mohd , Gan Seng Neon 
Published: June 2012

AbstractOligomeric hydroxyalkanoic acids have potential industrial, medical, and pharmaceutical applications and they can be produced from the degradation of high molecular weight polyhydroxyalkanoates by a number of different ways. Thermal decomposition takes place in the absence of organic solvent and other chemicals and this justified the method of producing low molecular weight PHA as green chemistry. The kinetics for thermal degradation of medium‐chain‐length polyhydroxyalkanoates (mcl‐PHA) prepared from saponified palm kernel oil (SPKO) was studied by thermogravimetric analysis (TGA) technique. Employing the nonisothermal Kissinger's method, the degradation activation energy, Ed, and pre‐exponential factor, A, were 129 kJ mol−1 and 1.15 × 1010 s−1, respectively. Specific degradation rate constant, k was found to increase at higher heating rate. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Hybrid polyaniline/nanomagnetic particles composites: High performance materials for EMI shielding
Authors: Kamchi Noureddine El , Belaabed Belkacem , Wojkiewicz Jean‐Luc , Lamouri Saad , Lasri Tuami 
Published: June 2012

AbstractIn this work, two types of hybrid composite materials were elaborated. The first based on polyaniline (PANI) doped Camphor Sulfonic acid (CSA), Carbon‐Coated Cobalt (CCo), and FeNi nanoparticles dispersed in polyurethane. A value of 104 S/m of conductivity and a 90 dB of shielding effectiveness in multilayer structure were obtained over the 8–18 GHz frequency band. The second type, based on PANI doped para‐toluene sulfonic acid (PTSA), dispersed in epoxy resin with FeNi nanoparticles. A thick material with moderate conductivity and high attenuation of electromagnetic waves was obtained. It was found that a PANI‐PTSA/FeNi/epoxy resin composite with thicknesses of 9.7 and 6.5 mm had, respectively, reflection loss values of −22 dB at 9.52 GHz, and −20.7 dB at 14.7 GHz. The electromagnetic properties of the elaborated structure hybrid materials can be optimized to increase the electromagnetic reflection–absorption properties. Thus, the obtained structure can be used in shielding and radar absorbing materials applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Political Violence: Transgenerational Inscription and Trauma
Authors: de Viñar Maren Ulriksen 
Published: June 2012

ABSTRACTThreatened by voices by popular dissent, some South American governments used massive imprisonments, systematic torture of prisoners, executions, indictments, and forced exile to silence and intimidate thousands of men and women. This profoundly disturbed all aspects of “normal” life from the co‐existence of different groups of the population to the core of the family.The traumatic effect produced by these events, which are both repressive to, and sustained in children's personality development, and the family as a whole, cannot be ignored. This article will look at the way in which terror is imprinted upon the psyche of victims of violence, and the effects of the transmission of that imprint from one generation to the next if there is no treatment intervention. The word “mark” is used to describe this imprint, its manifestations, and its effects on the psychic life of survivors and their children. The word “inscription” is used to describe the way in which this mark is burned into the psyche, just as the tattoos of Auschwitz were burned into the skin. Four case examples will elucidate how these histories of violence disturb the individual capacity to examine reality. They will explore the ways in which the defense mechnisms, built to insure psychic survival, are strained by the struggle between keeping the secret of umentionable and irresolvable horrors and the need to restore psychic continuity. Copyright © 2012 John Wiley & Sons, Ltd.
microRNAs as novel regulators of stem cell pluripotency and somatic cell reprogramming
Authors: Li Meng Amy , He Lin 
Published: June 2012

AbstractEmerging evidence suggests that microRNA (miRNA)‐mediated post‐transcriptional gene regulation plays an essential role in modulating embryonic stem (ES) cell pluripotency maintenance, differentiation, and reprogramming of somatic cells to an ES cell‐like state. Investigations from ES cell‐enriched miRNAs, such as mouse miR‐290 cluster and human miR‐302 cluster, and ES cell‐depleted miRNAs such as let‐7 family miRNAs, revealed a common theme that miRNAs target diverse cellular processes including cell cycle regulators, signaling pathway effectors, transcription factors, and epigenetic modifiers and shape their protein output. The combinatorial effects downstream of miRNA action allow miRNAs to modulate cell‐fate decisions effectively. Furthermore, the transcription and biogenesis of miRNAs are also tightly regulated. Thus, elucidating the interplay between miRNAs and other modes of gene regulation will shed new light on the biology of pluripotent stem cells and somatic cell reprogramming.
Determination of carbamazepine in human urine and serum samples by high‐performance liquid chromatography with post‐column Ru(bipy)‐Ce(SO4)2 chemiluminescence detection
Authors: Long Xing‐yu , Chen Fu‐nan 
Published: June 2012

ABSTRACTA novel, sensitive and rapid CL method coupled with high‐performance liquid chromatography separation for the determination of carbamazepine is described. The method was based on the fact that carbamazepine could significantly enhance the chemiluminescence of the reaction of cerium sulfate and tris(2,2‐bipyridyl) ruthenium(II) in the presence of acid. The chromatographic separation was performed on a Kromasil® (Sigma‐Aldrich) TM RP‐C18 column (id: 150 mm × 4.6 mm, particle size: 5 µm, pore size: 100 Å) with a mobile phase consisting of methanol–water‐glacial acetic acid (70:29:1, v/v/v) at a flowrate of 1.0 mL/min, the total analysis time was within 650 s. Under optimal conditions, CL intensity was linear for carbamazepine in the range 2.0 × 10−8 ~ 4.0 × 10−5 g/mL, with a detection limit of 6.0 × 10−9 g/mL (S/N = 3) and the relative standard detection was 2.5% for 2.0 × 10−6 g/mL (n = 11). This method was successfully applied to the analysis of carbamazepine in human urine and serum samples. The possible mechanism of the CL reaction is also discussed briefly. Copyright © 2012 John Wiley & Sons, Ltd.
Rapid screening and identification of α‐glucosidase inhibitors from mulberry leaves using enzyme‐immobilized magnetic beads coupled with HPLC/MS and NMR
Authors: Tao Yi , Zhang Yufeng , Cheng Yiyu , Wang Yi 
Published: June 2012

ABSTRACTα‐Glucosidase plays important roles in the digestion and absorption of carbohydrates in the small intestine. The inhibition of α‐glucosidase is regarded as a potential way to treat diabetes. We established an approach to screening α‐glucosidase inhibitors from medicinal plants using enzyme‐coated magnetic bead. Using 1‐(3‐dimethyl‐aminopropyl)‐3‐ethylcarbodiimide and N‐hydroxysuccinimide as reaction reagents, α‐glucosidase was immobilized on the magnetic beads by covalent linkage. The conjugation of α‐glucosidase to the magnetic beads was characterized using scanning electron microscope and X‐ray diffractometer. The proposed approach was applied in fishing potential α‐glucosidase inhibitors from extract of Morus alba, a Chinese medicinal plant. The structures of potential active compounds were identified via liquid chromatography–mass spectrometry and nuclear magnetic resonance. The results demonstrated that two flavonoids (isoquercitrin and astragalin) could bind to α‐glucosidase, which was confirmed via conventional α‐glucosidase inhibitory assay. Our findings suggested that enzyme‐coated magnetic beads may be suitable for discovering active compounds from medicinal plants. Copyright © 2012 John Wiley & Sons, Ltd.
Samarium‐exchanged Heteropoly Tungstate: An Efficient Solid Acid Catalyst for the Synthesis of Glycerol Carbonate from Glycerol and Benzylation of Anisole
Authors: Kumar Ch. Ramesh , Jagadeeswaraiah K. , Prasad P. S. Sai , Lingaiah N. 
Published: June 2012

AbstractSamarium‐exchanged heteropoly tungstate (SmxTPA) is an efficient catalyst for the synthesis of glycerol carbonate from glycerol and urea. The catalysts with varying Sm content were prepared and characterized by FT‐IR spectroscopy, XRD, laser Raman spectroscopy, temperature‐programmed desorption of ammonia, and X‐ray photo electron spectroscopy. The activity of the catalysts is related to the Lewis and Brønsted acidity, which depends on the Sm content in the catalysts. Partially exchanged SmxTPA catalyst showed high activity, owing to a higher number of Lewis acidic sites. The catalyst exhibited consistent activity and selectivity during recycling. A plausible reaction mechanism is presented. The catalyst also exhibited high activity in the acid‐catalyzed benzylation of anisole.
Kalorienfreie Süße aus Labor und Natur
Authors: Roth Klaus , Lück Erich 
Published: June 2012

AbstractZu üppige und zu süße Ernährung bei zu wenig Bewegung führten zur starken Gewichtszunahme großer Teile der Bevölkerung. Heute stehen 10 zugelassene kalorienfreie Süßstoffe zur Verfügung, um den großen Bedarf zu decken. Keiner von ihnen ist ideal, aber optimale Mischungen zeigen eine so gute Geschmacksqualität, dass selbst Gourmets den Zucker in verschiedenen Essenszubereitungen ersetzen können. Kalorienfreie Süßstoffe sind, trotz ihres schlechten Rufs in den Medien, eine wirkliche Erfolgsgeschichte. Die Chemie hat sie möglich gemacht.
Indigo auf Speicherchips
Authors: Harrer Roswitha 
Published: June 2012

AbstractBitte schön stone‐washed – Indigo ist seit Jahrtausenden als hervorragender Farbstoff für Textilien bekannt. Ganz neue Qualitäten scheint das Molekül jetzt in der Anwendung für eine nachhaltige und preiswerte Elektronik zu entfalten.
Long‐Term Outcomes of Device Closure of Very Large Secundum Atrial Septal Defects: A Comparison of Transcatheter vs Intraoperative Approaches
Authors: Guo Jin‐Jian , Luo Yu‐Kun , Chen Zhao‐Yang , Cao Hua , Yan Xiao‐Ping , Chen Hua , Peng Ya‐Fei , Lin Chao‐Gui , Chen Liang‐Long 
Published: June 2012

AbstractBackground:Transcatheter device closure (TCDC) and intraoperative device closure (IODC) have emerged as minimally invasive methods in the treatment of secundum atrial septal defects (ASDs), but the long‐term safety and efficacy remains uncertain for the large ASDs.Hypothesis:TCDC may be as safe and efficacious as IODC for closure of large ASDs in terms of long‐term clinical outcomes.Methods:Ninety‐two patients who had ASDs with a defect diameter of ≥30 mm were included in this study. The patients received either TCDC (n = 42) or IODC (n = 50). An Amplatzer septal occluder was used in both groups. The dumbbell‐like device deploying technique was introduced in the TCDC group. Physical exams, electrocardiography, and echocardiography were performed preprocedurally and postprocedurally at the index follow‐up visits.Results:The procedural immediate success rate was 97.6% for TCDC and 98.0% for IODC (P = 0.328). The rate of periprocedural complications was 9.5% for TCDC and 28.0% for IODC (P = 0.026). The mean hospital stay was 7.5 ± 2.7 days for TCDC and 11.9 ± 3.8 days for IODC (P < 0.001). For the mean follow‐up of 5.4 ± 0.5 years, there were no cardiac deaths and late complications in either group. No significant residual shunts were documented, and symptoms were significantly improved in both groups. Right and left ventricular diameter, pulmonary artery diameter, and pulmonary systolic pressure were all significantly decreased in both groups (P < 0.05).Conclusions:The present study confirmed the long‐term safety and efficacy for closing a large ASD either by TCDC or IODC. Either of them could become an effective alternative to the surgery for large ASD closure.The authors have no funding, financial relationships, or conflicts of interest to disclose.
Iron Resonant Photoemission Spectroscopy on Anodized Hematite Points to Electron Hole Doping during Anodization
Authors: Braun Artur , Chen Qianli , Flak Dorota , Fortunato Giuseppino , Gajda‐Schrantz Krisztina , Grätzel Michael , Graule Thomas , Guo Jinghua , Huang Tzu‐Wen , Liu Zhi , Popelo Anastasiya V. , Sivula Kevin , Wadati Hiroki , Wyss Pradeep P. , Zhang Liang , Zhu Junfa 
Published: June 2012

AbstractAnodization of α‐Fe2O3 (hematite) electrodes in alkaline electrolyte under constant potential conditions the electrode surface in a way that an additional current wave occurs in the cyclic voltammogram. The energy position of this current wave is closely below the potential of the anodization treatment. Continued cycling or exchanging of the electrolyte causes depletion of this new feature. The O 1s and Fe 2p core‐level X‐ray photoelectron spectra (XPS) and near‐edge X‐ray absorption fine structure (NEXAFS) spectra of such conditioned hematite exhibit a chemical shift towards higher binding energies, in line with the general perception that anodization generates oxide species with dielectric properties. The valence band XPS and particularly the iron resonant valence band photoemission spectra, however, are shifted towards the opposite direction, that is, towards the Fermi energy, suggesting that hole doping on hematite has taken place during anodization. Quantitative analysis of the Fe 2p resonant valence band photoemission spectra shows that the spectra obtained at the Fe 2p absorption threshold are shifted by virtually the same energy as the anodization potential towards the Fermi energy. The tentative interpretation of this observation is that anodization forms a surface film on the hematite that is specific to the anodization potential.
Directionality of Dihydrogen Bonds: The Role of Transition Metal Atoms
Authors: Filippov Oleg A. , Belkova Natalia V. , Epstein Lina M. , Lledos Agusti , Shubina Elena S. 
Published: June 2012

AbstractA theoretical study on two series of electron‐rich group 8 hydrides is carried out to evaluate involvement of the transition metal in dihydrogen bonding. To this end, the structural and electronic parameters are computed at the DFT/B3PW91 level for hydrogen‐bonded adducts of [(PP3)MH2] and [Cp*MH(dppe)] (M=Fe, Ru, Os; PP3=κ4‐P(CH2CH2PPh2)3, dppe= κ2‐Ph2PCH2CH2PPh2) with CF3CH2OH (TFE) as proton donor. The results are compared with those of adduct [Cp2NbH3]⋅TFE featuring a “pure” dihydrogen bond, and classical hydrogen bonds in pyridine⋅TFE and Me3N⋅TFE. Deviation of the H⋅⋅⋅HA fragment from linearity is shown to originate from the metal participation in dihydrogen bonding. The latter is confirmed by the electronic parameters obtained by NBO and AIM analysis. Considered together, orbital interaction energies and hydrogen bond ellipticity are salient indicators of this effect and allow the MH⋅⋅⋅HA interaction to be described as a bifurcate hydrogen bond. The impact of the M⋅⋅⋅HA interaction is shown to increase on descending the group, and this explains the experimental trends in mechanisms of proton‐transfer reactions via MH⋅⋅⋅HA intermediates. Strengthening of the M⋅⋅⋅H interaction in the case of electron‐rich 5d metal hydrides leads to direct proton transfer to the metal atom.
Efficient Excitation‐Energy Transfer in Ion‐Based Organic Nanoparticles with Versatile Tunability of the Fluorescence Colours
Authors: Yao Hiroshi , Ashiba Koji 
Published: June 2012

AbstractOrganic nanoparticles consisting of 3,3′‐diethylthiacyanine (TC) and ethidium (ETD) dyes are synthesized by ion‐association between the cationic dye mixture (10 % ETD doping) and the tetrakis(4‐fluorophenyl)borate (TFPB) anion, in the presence of a neutral stabilizing polymer, in aqueous solution. Doping with ETD makes the particle size smaller than without doping. Size tuning can also be conducted by varying the molar ratio (ρ) of the loaded anion to the cationic dyes. The fluorescence spectrum of TC shows good overlap with the absorption of ETD in the 450–600 nm wavelength region, so efficient excitation‐energy transfer from TC (donor) to ETD (acceptor) is observed, yielding organic nanoparticles whose fluorescence colours are tunable. Upon ETD doping, the emission colour changes significantly from greenish‐blue to reddish or whitish. This change is mainly dependent on ρ. For the doped nanoparticle sample with ρ=1, the intensity of fluorescence ascribed to ETD is ∼150‐fold higher than that from pure ETD nanoparticles (efficient antenna effect). Non‐radiative Förster resonance‐energy transfer (FRET) is the dominant mechanism for the ETD fluorescence enhancement. The organic nanoparticles of a binary dye system fabricated by the ion‐association method act as efficient light‐harvesting antennae, which are capable of transferring light energy to the dopant acceptors in very close proximity to the donors, and can have multi‐wavelength emission colours with high fluorescence quantum yields.