bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enantiomeric Recognition of Racemic 4‐Aryl‐1,4‐dihydropyridine Derivatives via Chiralpak AD‐H Stationary Phases
Authors: Dai Zhi , Pittman Charles U. , Li Tingyu 
Published: July 2012

ABSTRACTThe chromatographic chiral resolution of two new series of racemic 4‐substituted‐1,4‐dihydropyridine derivatives was studied on a commercial Chiralpak AD‐H column. Analytes without 5,5‐dimethyl substituents (1–15) are more efficiently resolved than analytes with 5,5‐dimethyl groups (16–30). The AD‐H column discriminated between enantiomers through both hydrogen bonding attractions and π–π interactions. This interpretation is in accord with plots of the logarithm of separation factors, log(α), versus σ (Hammett–Swain substituent parameter) and σ+ (Brown substituent constant) plots. By elucidating the effects of the remote substituents on these chiral separations, it was shown that the influence of π–π interaction forces increase when steric bulk effects act to decrease the hydrogen bonding attractive forces on the AD‐H column. Chirality 24:854–859, 2012. © 2012 Wiley Periodicals, Inc.
Using smooth particle hydrodynamics to investigate femoral cortical bone remodelling at the Haversian level
Authors: Fernandez J. W. , Das R. , Cleary P. W. , Hunter P. J. , Thomas C. D .L. , Clement J. G. 
Published: July 2012

SUMMARYIn the neck of the femur, about 70% of the strength is contributed by the cortical bone, which is the most highly stressed part of the structure and is the site where failure is almost certainly initiated. A better understanding of cortical bone remodelling mechanisms can help discern changes at this anatomical site, which are essential if an understanding of the mechanisms by which hips weaken and become vulnerable to fracture is to be gained. The aims of this study were to (i) examine a hypothesis that low strain fields arise because of subject‐specific Haversian canal distributions causing bone resorption and reduced bone integrity and (ii) introduce the use of a meshless particle‐based computational modelling approach SPH to capture bone remodelling features at the level of the Haversian canals. We show that bone remodelling initiated by strain at the Haversian level is highly influenced by the subject‐specific pore distribution, bone density, loading and osteocyte density. SPH is shown to be effective at capturing the intricate bone pore shapes that evolved over time. Copyright © 2012 John Wiley & Sons, Ltd.
A New Glimpse into the CO2‐Philicity of Carbonyl Compounds
Authors: Altarsha Muhannad , Ingrosso Francesca , Ruiz‐Lopez Manuel F. 
Published: July 2012

AbstractWe report a theoretical study on non‐conventional structures of 1:1 complexes between carbon dioxide and carbonyl compounds. These structures have never been reported before but are relevant for understanding the solubility of carbonyl compounds in supercritical CO2. The work is based on the results of ab initio calculations at the MP2 and CCSD(T) levels using aug‐cc‐pVDZ and aug‐cc‐pVTZ basis sets. Investigated systems include aldehydes, ketones and esters, together with some fluorinated derivatives. The results are interpreted in terms of natural bond orbital analyses. Harmonic vibrational frequency calculations have also been done in order to compare them with available experimental data. We show for the first time that complexes where CO2 behaves globally as a Lewis base are stable in the case of ketones and esters, but not in the case of aldehydes, and their stability is similar to that of traditional complexes in which CO2 behaves as a Lewis acid. This finding considerably modifies the concept of CO2‐philicity and may have important ramifications in the development of green reactions in supercritical CO2.
Application of a Versatile Nanoparticle Stabilizer in Phase Transfer and Catalysis
Authors: Biondi Ilaria , Laporte Vincent , Dyson Paul J. 
Published: July 2012

AbstractGold and rhodium nanoparticles stabilized by a cationic polymer can be readily modified by anion exchange to afford nanoparticles that may be dispersed in a wide range of organic solvents and ionic liquids. The catalytic activity of the Rh nanoparticle dispersions have been evaluated in the selective hydrogenation of limonene and the nature of the solvent has been shown to play a critical role.
An Iterative Method for the Synthesis of Symmetric Polyynes
Authors: DeCicco Racquel C. , Black Allison , Li Lei , Goroff Nancy S. 
Published: July 2012

AbstractAn iterative synthetic route for obtaining symmetric polyynes was developed, consisting of a series of iodination and Stille coupling reactions. The starting materials employed in this pathway are simple and can be prepared easily. Polyynes containing up to seven C≡C bonds were synthesized using this method. This route is particularly effective for accessing polyynes with an odd number of C≡C bonds and has allowed for the synthesis of a new iodine‐capped polyyne, diiododecapentayne.
SupraBox: Chiral Supramolecular Oxazoline Ligands
Authors: Durini Marco , Russotto Eleonora , Pignataro Luca , Reiser Oliver , Piarulli Umberto 
Published: July 2012

AbstractA new class of oxazoline ligands, named SupraBox, was studied. These ligands possess an additional urea functionality to generate supramolecular bidentate ligands in transition‐metal complexes, by the establishment of hydrogen bonds between the urea N‐hydrogens of one ligand and the carbonyl oxygen of a second one. A library of 16 SupraBox ligands was prepared using 5 differently substituted oxazoline nuclei, 4 linkers and 3 different urea substituents. The formation of copper(II) and palladium(II) complexes was investigated by MS, UV/Vis and 1H‐NMR spectroscopy. The SupraBox library was screened in the copper‐catalyzed asymmetric benzoylation of vic‐diols. Good selectivities were obtained in the kinetic resolution of racemic hydrobenzoin [up to 86 % ee and selectivity (s) = 28] and in the desymmetrization of meso‐hydrobenzoin (up to 88 % ee).
Changes in strawberry volatile sulfur compounds due to genotype, fruit maturity and sample preparation
Authors: Du Xiaofen , Whitaker Vance , Rouseff Russell 
Published: July 2012

ABSTRACTNineteen volatile sulfur compounds (VSCs), including ten thioesters and eight alkyl sulfides, were quantified using solid phase microextraction–gas chromatography–pulsed flame photometric detection in 12 Florida strawberry cultivars. The major headspace VSCs in all 12 cultivars were methanethiol and methyl thioacetate, together comprising 77–95% of the total VSCs. Concentrations for the 13 major strawberry VSCs were determined at five maturity stages. Puréed fruit produced 10–20 times more headspace volatiles than did intact berries. The relative distribution between total alkyl sulfides and total thioesters was similar from both sample preparation methods but the relative distribution of individual sulfides, especially alkyl sulfides, was appreciably different. VSCs found in the highest concentrations from intact fruit included methanethiol, dimethyl sulfide, dimethyl disulfide and dimethyl trisulfide. In puréed fruit, highest VSCs included hydrogen sulfide, sulfur dioxide and methional. The comparison of concentrations with odour threshold in water suggests that methanethiol was the predominant aroma active VSC at all maturity stages. Total volatile sulfurs (y) increased dramatically during the final two maturity stages (x = 3,4) as described by y = 92.929x2 − 111.41x + 28.457 (R2 = 0.996). ‘Strawberry Festival’ and ‘Florida Radiance’ were distinguished from 10 other cultivars in principal component analysis (PCA) score plots, primarily due to high thioester concentrations. ‘Dover’, ‘Rosa Linda’ and ‘Florida Belle’ were the oldest cultivars and formed a distinct group in the PCA score plot characterized by relatively high sulfide and low thioester concentrations. Relative VSC composition appears to be a genetically controlled trait. Copyright © 2012 John Wiley & Sons, Ltd.
Ruthenium Supported on Nitrogen‐Doped Carbon Nanotubes for the Oxygen Reduction Reaction in Alkaline Media
Authors: Mabena L. F. , Modibedi R. M. , Sinha Ray S. , Coville N. J. 
Published: July 2012

AbstractNitrogen‐doped carbon nanotubes (N‐CNTs) prepared via thermal chemical vapor deposition (CVD), were used to support ruthenium (Ru) nanoparticles made using a microwave assisted reduction technique. The amount of Ru deposited on N‐CNTs was varied between 0 and 10 wt.%. The activity of the prepared nanocatalysts toward the oxygen reduction reaction (ORR) was characterized using the rotating disk electrode and voltammetry techniques. The ORR activity was higher at lower concentrations of Ru on N‐CNTs. The four electron pathway of ORR is more favorable on 2Ru/N‐CNTs and 5Ru/N‐CNTs than 10Ru/N‐CNTs.
Effects of anxiolytic treatment on potentiated startle during aversive image anticipation
Authors: Acheson Dean T. , Stein Murray B. , Paulus Martin P. , Ravindran Lakshmi , Simmons Alan N. , Lohr James B. , Risbrough Victoria B. 
Published: July 2012

ObjectiveHeightened anticipation of future events has been characterized as a feature of certain anxiety disorders. In functional magnetic resonance imaging studies, anticipation of fearful/threatening images has been shown to robustly activate the insular cortex and amygdala in healthy subjects, in subjects with high trait anxiety, and in some with anxiety disorders. Blood oxygenation level dependent activation in response to negative image anticipation is also sensitive to anxiolytic treatment, suggesting that image anticipation probes anxiety systems. It is not clear, however, if behavioral responses to image anticipation are also sensitive to anxiolytics. This study tested the hypothesis that anxiety behaviors during anticipation of negative images are sensitive to anxiolytic treatment.MethodThis study examined the effects of alprazolam and pregabalin treatment on potentiated startle during affective image anticipation.ResultsThere was an effect of anticipation type (negative versus neutral versus positive) on startle reactivity and subjective ratings, suggesting that the task was effective in assaying negative anticipatory arousal. Both treatments significantly reduced overall startle magnitude. However, neither treatment specifically affected potentiated startle during aversive anticipation.ConclusionThese data suggest that potentiated startle in response to anticipation of aversive images is not sensitive to anxiolytic treatments in a healthy population, limiting its use as a predictive model of anxiolytic activity. This article is a US Government work and is in the public domain in the USA.
Spectrophotometric measurements of human tissues for the detection of subjacent blood vessels in an endonasal endoscopic surgical approach
Authors: Ernstberger Markus , Boeswetter Pascal , Baselt Tobias , Ebert Frank , Basan Fabiola , Steinke Hanno , Hammer Niels , Grunert Ronny , Hartmann Peter 
Published: July 2012

AbstractThin slices of human tissues are characterized concerning reflection and transmission in a wavelength range from 400 to 1700 nm. The results are primarily useful to find a wavelength for the detection of subjacent blood vessels during surgical procedures, especially neurological surgery. The measurements have been conducted using a customized measuring station, utilizing two halogen bulb lamps and two spectrometers. This paper focuses on creating a data base with the optical properties of artery, brain, bone, nasal mucosa, and nerve. The spectral distributions are compared among each other, similarities and differences are pointed out. Each tissue has got unique spectral characteristics, whereas typical absorption bands can be found in the overall tissues, especially hemoglobin and water absorption bands. The reflectivity maxima are typically located in the red or near‐infrared. All the transmission maxima are located between 1075 nm and 1100 nm. The measurements have been conducted at the Institute of Anatomy at the University of Leipzig. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
RMC_POT: A computer code for reverse monte carlo modeling the structure of disordered systems containing molecules of arbitrary complexity
Authors: Gereben Orsolya , Pusztai László 
Published: July 2012

AbstractAn approach has been devised and tested for preserving the molecular dynamics molecular geometry taking into account energetic considerations during Reverse Monte Carlo (RMC) modeling. Instead of the commonly used fixed neighbor constraints, where molecules are held together by constraining distance ranges available for the specified atom pairs, here molecules are kept together via bond, angle, and dihedral potential energies. The scaled total potential energy contributes to the measure of the goodness‐of‐fit, thus, the atoms can be prevented from drifting apart. In some of the calculations (Lennard‐Jones and Coulombic) nonbonding potentials were also applied. The algorithm was successfully tested for the X‐ray structure factor‐based structure study of liquid dimethyl trisulfide, for which material now significantly more sensible results have been obtained than during previous attempts via any earlier version of RMC modeling. It is envisaged that structural modeling of a large class of materials, primarily liquids and amorphous solids containing molecules of up to about 100 atoms, will make use of the new code in the near future. © 2012 Wiley Periodicals, Inc.
The role of the basis set and the level of quantum mechanical theory in the prediction of the structure and reactivity of cisplatin
Authors: Paschoal Diego , Marcial Bruna L. , Lopes Juliana Fedoce , De Almeida Wagner B. , Dos Santos Hélio F. 
Published: July 2012

AbstractIn this article, we conducted an extensive ab initio study on the importance of the level of theory and the basis set for theoretical predictions of the structure and reactivity of cisplatin [cis‐diamminedichloroplatinum(II) (cDDP)]. Initially, the role of the basis set for the Pt atom was assessed using 24 different basis sets, including three all‐electron basis sets (ABS). In addition, a modified all‐electron double zeta polarized basis set (mDZP) was proposed by adding a set of diffuse d functions onto the existing DZP basis set. The energy barrier and the rate constant for the first chloride/water exchange ligand process, namely, the aquation reaction, were taken as benchmarks for which reliable experimental data are available. At the B3LYP/mDZP/6‐31+G(d) level (the first basis set is for Pt and the last set is for all of the light atoms), the energy barrier was 22.8 kcal mol−1, which is in agreement with the average experimental value, 22.9 ± 0.4 kcal mol−1. For the other accessible ABS (DZP and ADZP), the corresponding values were 15.4 and 24.5 kcal mol−1, respectively. The ADZP and mDZP are notably similar, raising the importance of diffuse d functions for the prediction of the kinetic properties of cDDP. In this article, we also analyze the ligand basis set and the level of theory effects by considering 36 basis sets at distinct levels of theory, namely, Hartree‐Fock, MP2, and several DFT functionals. From a survey of the data, we recommend the mPW1PW91/mDZP/6‐31+G(d) or B3PW91/mDZP/6‐31+G(d) levels to describe the structure and reactivity of cDDP and its small derivatives. Conversely, for large molecules containing a cisplatin motif (for example, the cDDP‐DNA complex), the lower levels B3LYP/LANL2DZ/6‐31+G(d) and B3LYP/SBKJC‐VDZ/6‐31+G(d) are suggested. At these levels of theory, the predicted energy barrier was 26.0 and 25.9 kcal mol−1, respectively, which is only 13% higher than the actual value. © 2012 Wiley Periodicals, Inc.
Numerical harmonic modeling of long coupled transmission lines using matrix series theory and recursive approach
Authors: Weng Hua , Xu Zheng 
Published: July 2012

SUMMARYTo improve the efficiency of the harmonic analysis, this paper presents a direct phase‐domain harmonic model for long coupled transmission lines, which can take the parameter frequency dependence, the configuration asymmetry, and the untransposition of the line into consideration. The steps of the proposed modeling method are as follows. First, in the direct phase domain and on the basis of the travelling wave equation, the coupled transmission line model was derived in a nodal admittance matrix form. Then the matrix series theory was adopted to realize the numerical calculation of the nodal admittance matrix without relying on the eigenvalue and eigenvector calculations of the propagation matrix. Finally, a recursive approach was proposed to handle the nodal equation of the network containing long transmission lines. Both the accuracy and the efficiency of the proposed approach were verified by comparing with the exact method in which it is necessary to calculate the eigenvalues and eigenvectors of the propagation matrix. The computation time and memory consumption analysis indicates that the proposed approach excels the exact method in saving computation time and memory. It should be emphasized that, by utilizing the recursive approach, the proposed approach is always numerically stable and can also be applied to DC transmission lines. Copyright © 2012 John Wiley & Sons, Ltd.
Pectin methyl esterase treatment on high‐methoxy pectin for making fruit jam with reduced sugar content
Authors: Wang Yuh‐Tai , Lien Ling‐Lan , Chang Ya‐Chu , Wu James Swi‐Bea 
Published: July 2012

AbstractBACKGROUND: Pectin methyl esterase (PME) has been postulated to catalyse the transacylation reaction between pectin molecules. The present study aimed to prove the occurrence of this reaction. The feasibility of applying PME‐catalysed transacylation between high‐methoxy pectin molecules in making fruit jam with reduced sugar content was also investigated.RESULTS: PME treatment increased the turbidity and particle size in pectin solution and the molecular weight of pectin, while it decreased the number of methoxy ester linkages and the intensity of the CH3 absorption peak in the Fourier transform infrared spectrum without changes in the number of total ester linkages in pectin molecules. These findings support the occurrence of PME‐catalysed transacylation between pectin molecules. Higher values of hardness, gumminess and chewiness were found in a jam containing PME‐treated citrus pectin (10 g L−1) and sugar (350 g L−1) as compared with either a jam containing untreated citrus pectin (10 g L−1) and sugar (350 g L−1) or strawberry jam containing pectin (10 g L−1) from the fruit and sugar (650 g L−1).CONCLUSION: The demand for sugar in jam making can be greatly reduced by the use of PME‐treated high‐methoxy pectin. Copyright © 2012 Society of Chemical Industry
Direct Correlation Between Electric and Structural Properties During Solidification of Poly(3‐hexylthiophene) Drop‐Cast Films
Authors: Grodd Linda , Pietsch Ullrich , Grigorian Souren 
Published: July 2012

AbstractStructural and electrical properties of semicrystalline P3HT cast films onto Si/SiO2 surface are studied during the solidification under applied electric field in lateral OFET geometry. During evaporation of the solvent, the formation of P3HT crystallites is monitored simultaneously by time‐resolved X‐ray diffraction and by source‐drain current measurements. The electrical current is reaching its maximum in two pronounced regimes already before complete solidification of the polymer as detected by X‐ray diffraction intensities. The monitored complex time dependence of current and X‐ray intensities reveals a highest conducting level for the gel‐like state.
Optimum coupling and multimode excitation of traveling‐waves in a whole‐body 9.4T scanner
Authors: Geschewski Frank H. , Brenner Daniel , Felder Jörg , Jon Shah N. 
Published: July 2012

AbstractGiven the absence of a body coil, the radio frequency screen of a whole‐body 9.4T magnetic resonance imaging scanner can be used as a circular waveguide. In the unloaded case, the screen allows propagation of the dominant TE11‐ as well as the TM01‐mode. In the first part of this study, the optimum coupling of a circular polarized TE11‐mode was determined empirically for excitation and reception with a rectangular patch antenna. Employing full‐wave simulations, two simulation models and two phantoms, different patch positions were tested to find the optimum position with respect to coupled power and homogenous excitation field. The best simulation results were validated with measurements. The second part of this study describes the design and measurements of a multimode excitation device. Using the parallel transmit system of the MR scanner, all propagable traveling wave modes could be excited and detected independently. The performance of the multimode device related to field of view, B1+‐efficiency and radio frequency shimming was assessed by phantom measurements. Initial results show that three modes are sufficient to homogeneously excite regions of interest at 9.4 T. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Improving the Standard of Care for People with Ankylosing Spondylitis and a New Approach to Developing Specialist ESP‐Led AS Clinics
Authors: Van Rossen Liz , Withrington Robin H. 
Published: July 2012

AbstractObjectivesIn the UK, there is a wide variation in the quality of care that people with ankylosing spondylitis (AS) receive. People with AS require early diagnosis and referral to a specialist team to commence treatment and optimize outcome.MethodsAt East Kent Hospitals University Foundation Trust, a specialist clinic led by an extended scope practitioner (ESP) physiotherapist has been set up for the assessment and monitoring of patients with AS. This report describes the service provided by the AS clinic.ResultsOver eight years, the number of patients seen has risen from 62 to 352, and annual consultations from 186 to 986, with an average of 2.8 visits per patient per year. Ninety‐seven patients have started treatment with a Tumour Necrosis Factor (TNF) blocker. The service has expanded by the addition of a support worker and biologic clinics.ConclusionFor the Trust, the specialist service provides an improved quality of care and cost‐effective use of staff resources. Evaluation has demonstrated that patients welcome the new service. Copyright © 2012 John Wiley & Sons, Ltd.
GAG layer replenishment therapy for chronic forms of cystitis with intravesical glycosaminoglycans—A review
Authors: Madersbacher Helmut , van Ophoven Arndt , van Kerrebroeck Philip E.V.A. 
Published: July 2012

AbstractAimsGlycosaminoglycan (GAG) layer replenishment is a cornerstone in the therapy of interstitial cystitis (IC). During the last years intravesical GAG layer replenishment has proven to be an effective treatment for overactive bladder (OAB), radiation cystitis, and recurrent urinary tract infections (UTIs).MethodsExamination of different substances available for intravesical GAG replenishment and evaluation of the evidence for the treatment of the above‐mentioned conditions.ResultsWe searched the Medical Literature Analysis and Retrieval System Online (MEDLINE) database for studies on intravesical GAG replenishment. A total of 27 clinical studies remain relevant to this topic, many of them with mixed patient selection and suboptimal definition of symptom improvement/success. Two placebo controlled studies with hyaluronic acid failed to show superiority and have not been published. One active controlled randomized study has been published showing that chondroitin sulphate 0.2% has a clear benefit for OAB patients. Another study with chondroitin sulphate 2.0% failed to show statistically significant evidence, but was underpowered.ConclusionsA short number of randomized controlled studies confirm efficacy of intravesical GAG layer replenishment therapy. Concluded from the study background (which comprises also uncontrolled studies), so far chondroitin sulphate 0.2% is in favor for intravesical GAG layer replenishment therapy. In general, large‐scale trials are urgently needed to underline the benefit of this type of therapy. Neurourol. Urodynam. 32: 9–18, 2013. © 2012 Wiley Periodicals, Inc.