bluuebunny/crossref_metadata_2025 huggingface dataset:
The formation of 3‐ferrocenylpyrazole‐4‐carboxylates and alkylhydrazine insertion products from α‐ferrocenylmethylidene‐β‐oxocarboxylates
Authors: Klimova Elena I. , Klimova Tatiana , Alamo Marcos Flores , Stivalet José M. Méndez , Ramírez Lena Ruíz , Backinowsky Leon V. , García Marcos Martínez
Published: January 2011

The reactions of α‐ferrocenylmethylidene‐β‐oxocarboxylates (1, 2, 3a, and 3b) with N‐methyl‐ and N‐(2‐hydroxyethyl)hydrazines (5a, 5b) afford ethyl 1‐alkyl‐5‐aryl(methyl)‐3‐ferrocenylpyrazole‐4‐carboxylates (6a, 6b, 6c, 6d, 6e) (∼50%) and N‐alkylhydrazine insertion products, viz., ethyl (N′‐acyl‐N′‐alkylhydrazino)‐3‐ferrocenylpropanoates (7a, 7b, 7c, 7d, 7e) (∼20%) and 1‐acyl‐2‐(N′‐alkyl‐N′‐ethoxycarbonylhydrazino)‐2‐ferrocenylethanes (8a, 8b, 8c, 8d, 8e) (∼10%). The structures of the compounds obtained were established based on the spectroscopic data and X‐ray diffraction analysis (for pyrazoles 6a and 6b). J. Heterocyclic Chem., (2011).
Non‐thermal internal energy distribution of ions observed in an electrospray source interfaced with a sector mass spectrometer
Authors: Rondeau David , Galland Nicolas , Zins Emilie‐Laure , Pepe Claude , Drahos László , Vékey Károly
Published: January 2011

The internal energy distribution P(Eint) of ions emitted in an electrospray (ESI) source interfaced with a sector mass spectrometer is evaluated by using the experimental survival yield (SY) method including the kinetic shift. This method is based on the relationship between the degree of fragmentation of an ion and its amount of internal energy and uses benzylpyridinium cations due to their simple fragmentation scheme. Quantum chemical calculations are performed, namely at G3(MP2)//B3LYP and QCISD/MP2 levels of theory. The results show that the internal energy distribution of the ions emitted in the ESI source interfaced with a sector analyzer is very narrow. The MassKinetics software is used to confirm these observations. The P(Eint) is the parameter that allows to fit the experimental SY of each substituted benzylpyridinium cation with theoretical mass spectra generated by the MassKinetics software. The resulting internal energy distributions are similar to the ones obtained with the experimental SY method. This indicates that in the present experimental conditions, P(Eint) cannot be compared with a ‘thermal‐like’ Boltzmann distribution. In addition, it appears that with the sector analyzer, increasing the collision energy in the first pumping stage of the ESI source does not correspond to a warm‐up of the produced ions. Copyright © 2011 John Wiley & Sons, Ltd.
Short or long fusion after thoracolumbar burst fractures does not alter selected gait parameters: a preliminary study
Authors: Oken Fuad , Yildirim Ozgur , Oken Oznur , Gulcek Murat , Yavuzer Gunes , Ucaner Ahmet
Published: January 2011

We evaluated the gait characteristics of patients who had short or long‐segment fusion after thoracolumbar burst fractures. The study included 12 patients (5 male, 7 female) who had vertebral fusion after traumatic thoracolumbar region (T12‐L2) burst fractures. Patients were divided into two groups based on fixation type (short or long segment). Twelve healthy age and sex‐matched subjects (seven male, five female) served as controls. Quantitative gait data, including all time‐distance (walking velocity, cadence, step time, step length, double support time), kinematic (joint rotation angles of pelvis, hip, knee, and ankle), and kinetic data (moments of hip in sagittal and coronal plane) were collected. Three patients had a T12, six patients an L1, and three patients had an L2 lesion. Patients in the two groups were similar in terms of age, sex, and time since operation. No significant differences were found in the time‐distance, kinematic, and kinetic gait characteristics between the two groups. This preliminary study reveals that the gait characteristics of patients with short and long‐segment fusion after thoracolumbar burst fractures were similar to those of healthy subjects and did not differ from each other. However, the present results should be interpreted with caution due to the small sample size. Future studies with larger groups are needed to provide additional data to validate these findings. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:915–918
Anterior border of the tibia as a landmark for extramedullary alignment guide in total knee arthroplasty for varus knees
Authors: Fukagawa Shingo , Matsuda Shuichi , Mitsuyasu Hiroaki , Miura Hiromasa , Okazaki Ken , Tashiro Yasutaka , Iwamoto Yukihide
Published: January 2011

A disadvantage to using extramedullary alignment guides of the tibia for total knee arthroplasty (TKA) is difficulty in correctly identifying the ankle center. The anterior border of the tibia is easily palpable, as it is not covered by muscles and its shape is convex anteriorly. We hypothesized that appropriate points exist along the anterior border that can be used as landmarks for extramedullary guides. Prior to TKA, computed tomographic images of the entire tibia were obtained from 101 osteoarthritic knees with varus deformities. The relationship between the lines connecting two points on the anterior border and the mechanical axis was evaluated using 3D imaging software. The mean angles between each of 10 determined axes and the mechanical axis varied from 3.2° varus to 2.1° valgus in the coronal plane. In the sagittal plane, all axes referencing the anterior border of the tibia showed anterior inclination to the mechanical axis. The line connecting the medial one‐third of the patellar tendon attachment and the distal one‐fourth of the anterior border, however, was highly consistent and parallel to the mechanical axis in the coronal plane. This axis can be effectively used as a landmark for extramedullary guides during TKA. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:919–924
Cryoinsult parameter effects on the histologically apparent volume of experimentally induced osteonecrotic lesions
Authors: Goetz Jessica E. , Robinson Duane A. , Pedersen Douglas R. , Conzemius Michael G. , Brown Thomas D.
Published: January 2011

Investigation of femoral head osteonecrosis would benefit from an animal model whose natural history includes progression to bony collapse of a segmental necrotic lesion. The bipedal emu holds attraction for systematic organ‐level study of collapse mechanopathology. One established method of experimentally inducing segmental lesions is liquid nitrogen cryoinsult. Four cryoinsult parameters—hold temperature, freeze duration, freeze/thaw repetition, and thaw duration—were investigated to determine their individual and combined effects on resulting necrotic lesion morphology. 3D distributions of histologically apparent osteocyte necrosis from 24 emus receiving varying cryoinsults were used to develop univariate and multivariate linear regression models relating resulting necrotic lesion morphology to particular cryoinsult input parameters. These models were then applied to predict lesion size in four additional emus receiving differing input cryoinsults. The best multivariate regression model predicted lesion volumes that were accurate to better than 8% of overall emu femoral head volume. The hold temperature during cryoinsult was by far the most influential cryoinsult input parameter. The utility of this information is to enhance the consistency and predictability of cryoinsult‐induced segmental lesion size for the purposes of systematic laboratory studies at the whole‐organ level. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:931–937
Surveying the ‘empty land’ in selected South African landscape postcards
Authors: van Eeden Jeanne
Published: January 2011

This paper adds to the discourse around picture postcards by looking at a number of South African postcards and photographs from about the 1940s to the 1970s wherein the object of the gaze is the supposedly empty landscape. These postcards simultaneously reveal and conceal the political and social realities of South Africa at that time by only showing white people gazing at the land. It is argued that the accessible and portable nature of postcards made them an ideal medium by which white peoples' relationship with the land was rehearsed and enacted during a decisive period of South African history. Copyright © 2011 John Wiley & Sons, Ltd.
Adhesion of Preosteoblasts and Fibroblasts onto Poly(pentafluorostyrene)‐Based Glycopolymeric Films and their Biocompatibility
Authors: Babiuch Krzysztof , Becer C. Remzi , Gottschaldt Michael , Delaney Joseph T. , Weisser Jürgen , Beer Birgitt , Wyrwa Ralf , Schnabelrauch Matthias , Schubert Ulrich S.
Published: January 2011

An efficient and metal‐catalyst free method of glycopolymer synthesis via thiol/para‐fluorine “click” reaction was used to graft acetylated 1‐thio‐β‐D‐glucopyranose and 1‐thio‐β‐D‐galactopyranose onto a homopolymer of pentafluorostyrene (PFS) as well as onto a block copolymer of styrene and PFS. Subsequent deprotection of the carbohydrate moieties yielded well‐defined, sugar‐modified polymers (PDI < 1.2). The prepared polymers were not cytotoxic against 3T3 fibroblasts and MC3T3‐E1 preosteoblasts. Furthermore, the water‐insoluble copolymers were drop‐cast and examined as synthetic biocompatible coatings on poly(propylene) substrates for culturing the investigated cell types. Both fibro‐ and preosteoblasts showed stable adhesion and proliferation on the glycopolymer‐coated surfaces.

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Synthesis of High‐Molecular‐Weight Tulipalin‐A‐Based Polymers by Simple Mixing and Heating of Comonomers
Authors: Agarwal Seema , Kumar Rimpu
Published: January 2011

The preparation of a polymer based on Tulipalin A with degradable ester linkages and high glass transition temperature with good processability, and solubility in various organic solvents is reported. The reaction was performed by mixing Tulipalin A and 2‐methylene‐1,3‐dioxepane (MDO) at high temperatures (70 °C and above) in the entire composition range without any initiator. The polymerization mechanism is found to be different from mere thermal initiation at high temperature. It was a combination of ionic and radical mechanism as proved by different methods. Microstructure analysis was done by 1D and 2D NMR techniques. The reactions were also tuned for different structures with varied properties by adding either the radical trapping agent or radical generators in the system.

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Ring Opening Metathesis Polymerization Derived Polymers as Photoresists: Making Use of Thiol‐ene Chemistry
Authors: Wolfberger Archim , Rupp Barbara , Kern Wolfgang , Griesser Thomas , Slugovc Christian
Published: January 2011

Ring opening metathesis polymerization derived poly(norbornene) films and aggregates were crosslinked via photo chemically induced thiol‐ene chemistry using a multifunctional thiol and the double bonds present in the polymer backbones. The presented method was illustrated by the description of a negative‐toned photoresist formulation based on above mentioned ingredients.

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Dual Stimuli‐Responsive Polymeric Micelles Exhibiting “AND” Logic Gate for Controlled Release of Adriamycin
Authors: Wei Chuan , Guo Jia , Wang Changchun
Published: January 2011

A new controlled release polymer micelle was designed and synthesized based on the concept of the “AND” logic with two orthogonal molecular triggers, namely pH and reduction, for intracellular drug delivery. Specifically, a hydrazine functionalized PEO‐b‐PMAA block copolymer was used to attach adriamycin (ADR) through the formation of hydrazone, then the as‐prepared ADR‐conjugated block copolymer micelles could be crosslinked by dithiodiethanoic acid. ADR was found to release most efficiently under both the low pH and the reductive conditions. This smart device is therefore equipped with two triggers with the “AND” logic for the releasing action, which is suitable for more complicated physiological conditions because the “ON” state is only realized under the simultaneous presence of the dual signal stimuli.

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The prevalence and clinical characteristics of punding in Parkinson's disease
Authors: Spencer Ashley H. , Rickards Hugh , Fasano Alfonso , Cavanna Andrea E.
Published: January 2011

Background: Punding (the display of stereotyped, repetitive behaviors) is a relatively recently discovered feature of Parkinson's disease (PD). Little is known about the prevalence and clinical characteristics of punding in PD. Methods: In this review, four large scientific databases were comprehensively searched for literature in relation to punding prevalence and clinical correlates in the context of PD. Results: Prevalence was found to vary greatly (between 0.34 to 14%), although there were large disparities in study populations, assessment methods, and criteria. We observed an association between punding, dopaminergic medications, and impulse control disorder. Other characteristics, which may be more common among punders, include a higher severity of dyskinesia, younger age of disease onset, longer disease duration, and male gender. Discussion: More research in large clinical datasets is required in many areas before conclusions are drawn. The pathophysiology behind the punding phenomenon is also poorly understood at present, rendering it difficult to develop targeted therapy. The current mainstay of treatment is the reduction in the dose of dopaminergic medications, the evidence for other suggested therapies being purely empirical. © 2011 Movement Disorder Society
Flat and Easy: 2D Depiction of Protein‐Ligand Complexes
Authors: Stierand Katrin , Rarey Matthias
Published: January 2011

Visualization of molecular complexes is commonly used to support the investigation of interaction patterns formed between the members of a molecular complex ensemble. Similar to the representation of single small molecules as structure diagrams, a schematic two‐dimensional design of molecular complexes features several advantages. This visualization mode enables the peer to scan large numbers of complexes in short time, originating for example from a virtual screening or de novo design campaign, and to get an impression of their quality. In addition, the diagrams can be printed on hardcopies without information loss and are therefore well suited for publications and talks. We will give an overview of the existing algorithms for the automatic generation of two‐dimensional complex diagrams. The reduction of dimensions from three to two is a quite difficult task since the resulting layout has to be more or less free of overlaps and has to follow esthetical guidelines. All programs proceed on input being composed of the three‐dimensional ligand and receptor coordinates. Due to the lack of guiding principles, the algorithms and resulting diagrams of the different available tools substantially differ in graphical styles, level of detail, and information content.
National Children's Study: Update in 2010
Authors: Hirschfeld Steven , Songco David , Kramer Barnett S. , Guttmacher Alan E.
Published: January 2011

The National Children's Study will examine the effects of the environment and genetics on the growth, development, and health of children across the United States; it will follow participants from before birth until age 21 years. The goal of the study is to improve the health and well‐being of children and contribute to understanding the roles various factors play in health and disease. Findings from the study will be made available as the research progresses, making potential benefits known to the public as soon as possible. A robust pilot study, or Vanguard Study, is underway to generate data for designing the subsequent Main Study. The goals of the Vanguard Study are feasibility, acceptability, and cost, and the goals of the Main Study will be exposure‐response relationships and biological, environmental, and genetic interactions. The initial Vanguard Study experience among 7 study centers was successful in many ways, including delineating the topics to explore for the next phase of the Vanguard Study. Three different recruitment strategies are under evaluation to determine what approach to use for the Main Study. The organization of National Children's Study operations is currently based on a new decentralized business model. Mt Sinai J Med 78:119–125, 2011. © 2011 Mount Sinai School of Medicine
On semi‐analytical probabilistic finite element method for homogenization of the periodic fiber‐reinforced composites
Authors: Kamiński Marcin
Published: January 2011

The main aim of this paper is a development of the semi‐analytical probabilistic version of the finite element method (FEM) related to the homogenization problem. This approach is based on the global version of the response function method and symbolic integral calculation of basic probabilistic moments of the homogenized tensor and is applied in conjunction with the effective modules method. It originates from the generalized stochastic perturbation‐based FEM, where Taylor expansion with random parameters is not necessary now and is simply replaced with the integration of the response functions. The hybrid computational implementation of the system MAPLE with homogenization‐oriented FEM code MCCEFF is invented to provide probabilistic analysis of the homogenized elasticity tensor for the periodic fiber‐reinforced composites. Although numerical illustration deals with a homogenization of a composite with material properties defined as Gaussian random variables, other composite parameters as well as other probabilistic distributions may be taken into account. The methodology is independent of the boundary value problem considered and may be useful for general numerical solutions using finite or boundary elements, finite differences or volumes as well as for meshless numerical strategies. Copyright © 2011 John Wiley & Sons, Ltd.
High‐quality surface remeshing using harmonic maps—Part II: Surfaces with high genus and of large aspect ratio
Authors: Marchandise E. , de Wiart C. Carton , Vos W. G. , Geuzaine C. , Remacle J.‐F.
Published: January 2011

This paper follows a previous one that was dealing with high‐quality surface remeshing using harmonic maps (Int. J. Numer. Meth. Engng 2010; 83:403–425). In (Int. J. Numer. Meth. Engng 2010; 83:403–425), it has been demonstrated that harmonic parametrizations can be used as input for surface meshers to produce high‐quality triangulations. However, two important limitations were pointed out, namely surfaces with high genus and/or of large aspect ratio. This paper addresses those two issues. We first develop a multiscale version of the harmonic parametrization of (Int. J. Numer. Meth. Engng 2010; 83:403–425) and then combine it with a multilevel partitioning algorithm to come up with an automatic remeshing algorithm that overcomes the above‐mentioned limitations of harmonic maps. The overall procedure is implemented in the open‐source mesh generator Gmsh (Int. J. Numer. Meth. Engng 2009; 79(11): 1309–1331). Copyright © 2011 John Wiley & Sons, Ltd.
Predictors of finding benefit after lung cancer diagnosis
Authors: Thornton Andrea A. , Owen Jason E. , Kernstine Kemp , Koczywas Marianna , Grannis Frederic , Cristea Mihaela , Reckamp Karen , Stanton Annette L.
Published: January 2011

Objective: We examined benefit finding in patients with lung cancer, including level of benefit finding and change in benefit finding over time, and tested a predictive model postulating that greater impact of and engagement with the stressor promotes benefit finding.

Methods: Patients diagnosed with a primary lung cancer within the past 6 months (M=16 weeks post‐diagnosis) completed measures of benefit finding, cancer‐related intrusions, perceived stressfulness, coping, and demographic and medical information at study entry (T1; n = 118) and 3 months later (T2; n = 79).

Results: Level of benefit finding at both assessments was to a ‘mild‐to‐moderate degree’. Benefit finding increased over time for patients with small cell carcinoma, but not for those with nonsmall cell carcinoma. The proposed model explained 33% of the variance in T1 benefit finding, and 64% (using T1 coping measures) and 71% (using T2 coping measures) of the variance in T2 benefit finding. Greater benefit finding was associated with having small cell lung cancer, higher cancer‐related intrusions, lower perceived cancer‐related stress, and greater approach‐oriented coping. Positive reframing coping emerged as the single unique approach‐oriented coping scale predicting benefit finding at T1, and emotional approach coping was the single unique approach‐oriented coping scale predicting benefit finding at T2.

Conclusion: Findings provide general support for a theoretical model positing that stressor impact and engagement with the stressor contribute to the development of benefit finding after cancer. Future research with larger, more diverse samples is needed to confirm and extend these findings. Copyright © 2011 John Wiley & Sons, Ltd.
The ensemble folding kinetics of the FBP28 WW domain revealed by an all‐atom Monte Carlo simulation in a knowledge‐based potential
Authors: Xu Jiabin , Huang Lei , Shakhnovich Eugene I.
Published: January 2011

In this work, we apply a detailed all‐atom model with a transferable knowledge‐based potential to study the folding kinetics of Formin‐Binding protein, FBP28, which is a canonical three‐stranded β‐sheet WW domain. Replica exchange Monte Carlo simulations starting from random coils find native‐like (Cα RMSD of 2.68 Å) lowest energy structure. We also study the folding kinetics of FBP28 WW domain by performing a large number of ab initio Monte Carlo folding simulations. Using these trajectories, we examine the order of formation of two β‐hairpins, the folding mechanism of each individual β‐hairpin, and transition state ensemble (TSE) of FBP28 WW domain and compare our results with experimental data and previous computational studies. To obtain detailed structural information on the folding dynamics viewed as an ensemble process, we perform a clustering analysis procedure based on graph theory. Further, a rigorous Pfold analysis is used to obtain representative samples of the TSEs showing good quantitative agreement between experimental and simulated Φ values. Our analysis shows that the turn structure between first and second β strands is a partially stable structural motif that gets formed before entering the TSE in FBP28 WW domain and there exist two major pathways for the folding of FBP28 WW domain, which differ in the order and mechanism of hairpin formation. Proteins 2011. © 2011 Wiley‐Liss, Inc.
A comparison of the dynamics of pantothenate synthetase from M. tuberculosis and E. coli: Computational studies
Authors: Tan Yaw Sing , Fuentes Gloria , Verma Chandra
Published: January 2011

Pantothenate synthetase (PS) catalyzes the final step of the pantothenate pathway, in which pantothenate is formed from pantoate and β‐alanine in an ATP‐dependent reaction. Mycobacterium tuberculosis PS (MTB PS) is functionally a dimer and a potential target for novel antitubercular drugs. Molecular dynamics simulations show that the functional dynamics of the enzyme are dominated by motions of a flexible gate loop in the N‐terminal domain and of the C‐terminal domain. The gate loop motions dominate in MTB PS while the C‐terminal domain motion dominates in Escherichia coli PS. Simulations also show that the correlated motions of the domains are severely compromised in the monomeric forms. Mutations that reduce the mobility of the gate loop in MTB PS and increased it in E. coli PS were designed and validated through simulations. Proteins 2011; © 2011 Wiley‐Liss, Inc.
Investigating the reliability and criticality of the maintenance characteristics of a diving support vessel
Authors: Turan O. , Lazakis I. , Judah S. , Incecik A.
Published: January 2011

Maintenance tasks and their application in the shipping industry have evolved significantly in the recent years. Particularly in the offshore industry, safety onboard, environmental protection and intensive operational activities necessitate the minimization of down‐time and the preservation of an excellent performance ratio. The first step of an innovative ship maintenance strategy, which is proposed by the authors and is based on criticality and reliability assessment, is presented herein using the FTA tool with time‐dependant dynamic gates so as to represent in an accurate and comprehensive way the interrelation of the components of a system. The paper also presents a review of the maintenance standards and procedures, such as the ALARP concept, the Key Programme 3‐Asset Integrity (KP3) initiative, the OREDA handbook as well as the RCM and RBI principles. As part of the reliability assessment, the Birnbaum and Criticality reliability importance measures are utilized to validate the results of the analysis. A case study of a diving support vessel (DSV) illustrates the application of this strategy. The main systems examined are: the vessel's power plant, propulsion, water system, lifting, hauling and anchoring, diving and finally the safety system. The reliability of the main systems and subsystems as well as of their critical components is identified and suggestions of how to improve the overall reliability of the various systems both at a component, system and managerial level are also proposed. Copyright © 2011 John Wiley & Sons, Ltd.
Hypergraph list coloring and Euclidean Ramsey theory
Authors: Alon Noga , Kostochka Alexandr
Published: January 2011

A hypergraph is simple if it has no two edges sharing more than a single vertex. It is s‐list colorable (or s‐choosable) if for any assignment of a list of s colors to each of its vertices, there is a vertex coloring assigning to each vertex a color from its list, so that no edge is monochromatic. We prove that for every positive integer r, there is a function dr(s) such that no r‐uniform simple hypergraph with average degree at least dr(s) is s‐list‐colorable. This extends a similar result for graphs, due to the first author, but does not give as good estimates of dr(s) as are known for d2(s), since our proof only shows that for each fixed r ≥ 2, dr(s) ≤ 2 We use the result to prove that for any finite set of points X in the plane, and for any finite integer s, one can assign a list of s distinct colors to each point of the plane so that any coloring of the plane that colors each point by a color from its list contains a monochromatic isometric copy of X. © 2011 Wiley Periodicals, Inc. Random Struct. Alg., 2011
Mainstreaming sustainable coffee
Authors: Kolk Ans
Published: January 2011

This overview article examines the various dimensions of sustainable coffee as well as the actors involved and their perceptions of how to advance the market from niche to mainstream. The issues at hand are very complex, with different types of coffee producers, manufacturing/roasting companies and consumers, and a variety of standards, all with their own peculiarities and views on what is the best approach, and characterized by a divergent potential for ‘scaling up’. Policymakers, managers and NGOs thus face difficult choices as to which path to pursue as there is no clear consensus on a concrete ‘solution’ to this ‘wicked problem’. The article analyses the market for sustainable coffee, the different types of certified coffee available and their peculiarities considering production and supply perspectives, in relation to consumers who buy the final product. Implications are discussed as well, in the context of complexity and confusion, and the need for more complementarity. Copyright © 2011 John Wiley & Sons, Ltd and ERP Environment.
Error‐preserving local transformations on communication protocols
Authors: Kapus‐Kolar Monika
Published: January 2011

Recently, two transformations were proposed for modifying a member of a closed system of communicating state machines (CSMs) without considering the other CSMs and nevertheless securing that after the modification, the system can reach the same dead states and overfill the same channels, where channels are assumed to be error‐free unidirectional first‐in‐first‐out queues. When verifying the general correctness properties of a communication protocol whose specification is such a system, one can employ the two error‐preserving local transformations (EPLTs) for simplifying individual CSMs and thereby the subsequent reachability analysis. The paper proves four new simple EPLTs and a generic EPLT which strongly generalizes all the six EPLTs and from which further easily applicable EPLTs can be derived simply by specialization. For each of the EPLTs, it also discusses how (non‐)executability of CSM transitions in the new system version reflects (non‐)executability of those in the old one. Copyright © 2011 John Wiley & Sons, Ltd.
Organocatalysis: Cinchona catalysts
Authors: Marcelli Tommaso
Published: January 2011

The resurgence of asymmetric organocatalysis has been accompanied by the development of countless synthetic methodologies making use of Cinchona alkaloids (or their derivatives) as catalysts. Although important steps have been made in the understanding of the mode of action of this class of compounds, the development of new catalytic methodologies is largely carried out using experiment‐driven approaches. This overview presents a selection of computational results on the behavior of Cinchona alkaloids with respect to their structure, the way they interact with other species, and, ultimately, their catalytic activity. The twofold aim of this contribution is to provide organic chemists with accessible information on computational results as well as to present theoretical chemists an overview of the methods commonly used to model Cinchona organocatalysts, and how they are comparable to experimental results. © 2011 John Wiley & Sons, Ltd. WIREs Comput Mol Sci 2011 1 142–152 DOI: 10.1002/wcms.2

This article is categorized under:

Structure and Mechanism > Molecular Structures

Electronic Structure Theory > Density Functional Theory

Theoretical and Physical Chemistry > Reaction Dynamics and Kinetics
Hyperconjugation
Authors: Alabugin Igor V. , Gilmore Kerry M. , Peterson Paul W.
Published: January 2011

This review outlines the ubiquitous nature of hyperconjugative interactions and their role in the structure and reactivity of organic molecules. After defining the common hyperconjugative patterns, we discuss the main factors controlling the magnitude of hyperconjugative effects, including orbital symmetry, energy gap, electronegativity, and polarizibility. The danger of underestimating the magnitude of hyperconjugative interactions are illustrated by a number of spectroscopic, conformational, and structural effects. Through the use of advanced computational techniques, the true role of hyperconjugative effects, as it pertains to their influence on stereoelectronics, conformational equilibria, and reactivities relative to other electronic effects, continue to be uncovered. © 2011 John Wiley & Sons, Ltd.WIREs Comput Mol Sci2011 1 109–141 DOI: 10.1002/wcms.6

This article is categorized under:

Structure and Mechanism > Molecular Structures
205Tl‐NMR‐spektroskopische Untersuchungen an Thallium(I)‐und Organothallium(III)‐Verbindungen
Authors: Köppel H. , Dallorso J. , Hoffmann G. , Walther B.
Published: January 2011

Inhaltsübersicht. Mittels 205Tl‐Breitlinien‐ und hochauflösender 1H‐NMR wurden Tl(I)‐sowie Organothallium(III)‐Verbindungen untersueht und 205Tl‐ und 1H‐chemische Verschiebungen sowie 205Tl‐1H‐Kopplungskonstanten ermittelt. Die NMR‐Parameter dor Tl(I)‐Verbindungen wurden mit Literaturwerten verglichen. Die paramagnetischen 205Tl‐Verschiebungen von Verbindungen des Type R2TlX (R = Me, Et. n‐Pr, Ph; X = NO3, F, Br, J) werden in Bezug auf Substituenten., Losungsmittel‐ und Konzentrationseinflüsse diskutiert. Auf der Basis eines 0.3 molaren wäßrigen TINO3‐Primärstandards werden die 205Tl‐Verschiebungen in einer einheitlichen Verschiebungsskala geordnet und nach bindungstheoretischen Gesichtspunkten verglichen.

205Tl‐N.M.R.‐Spectroscopical Studies on Thallium(I) and Organothallium(III) Compounds

Abstract. Tl(I) and organothallium(III) compounds are investigated by means of 205Tl wide line and high resolution 1H‐n.m.r. and 1H chemical shifts as well as 205Tl‐2H coupling constants are estimated. The n.m.r.‐parameters of the Tl(I) compounds are compared with the values of the literature. The paramagnetic 205Tl shifts of compounds of the type R2TlX (R = Me. Et, n‐Pr. Ph; X = NO3, F, Br. I) are discussed with reference to the influence of substituents, solvents, and concentrations. The 205Tl shifts are arranged on the basis of a 0.3 M aqueous TlNO3 primary standard in a uniform shift scale and compared as to theoretical aspects of chemical bonds.

Für die großzügige Unterstützung unserer Arbeit danken wir Herrn Prof. Dr. K.‐D. Schleinitz.
Die Schwingungsspektren und Kraftkonstanten der Anionen MoOF–5 MoOF2–5, MoF–6 und WOF–5
Authors: Beuter A. , Sawodny W.
Published: January 2011

Inhaltsübersicht. Die Schwingungsspektren der Verbindungen CsMoOF5, MWOF5 (M = K, Rb, Cs), K2MoOF5, K2MoOF5 · H2O, K2MoOF5 · KHF2 und MMoF5 (M = K, Cs) wurden aufgenommen und zugeordnet. Aus den so ermittelten Normalschwingungsfrequenzen wurden für die Ionen MoOF5–, WOF5–, MoOF52– und MoF–5 Kraftkonstanten nach einem modifizierten Valenzkraftfeld berechnet. Anhand der erhaltenen Werte der Valenzkraftkonstanten werden die Bindungs‐verhältnisse diskutiert.

Vibrational Spectra and Force Constants of the Anions M0OF5–, MoOF52–, MoF–6, and WOF5–

Abstract. The vibrational spectra of CsMoOF5, MWOF5 (M = K, Rb, Cs), K2MoOF5, K2MoOF5 · H2O, K2MoOF5 · KHF2, and MMoF5 (M = K, Cs) have been recorded and assigned. The vibrational frequencies were used to calculate MVFF constants for the ions MoOF5–, WOF5–, MoOF52–, and MoF–6. The stretching force constants are discussed relative to the bond properties.
Festkörperreaktionen in Chalkogenidsysfemen, IV [1]: Röntgenographische und elektrische Untersuchungen am System HgCr2(SexS1–x)4
Authors: Lutz H. D. , Okoń ska‐Kozlowska I.
Published: January 2011

Inhaltsübersicht. Im Spinellsystem HgCr2SexS1–x)4 besteht im Gegensatz zu den entsprechenden Zink‐ und Cadmiumverbindungen, die lückenlose Mischkristallreihen bilden, zwischen 0,20 < x < 0.75 einp Mischungslücke. Im Bereich der Mischungslücke werden HgSe und Cr2S3–ySey‐Mischkristalle gebildet. Die Gitterkonstanten der Spinellmischkristalle erfüllen nur auf der selenreichen Seite des Phasendiagramms die Végardsche Regel. Der Reaktionsverlauf wurde mit Hilfe von Leitfähigkeitsmessungen sowie thermoanalytischer Untersuchungen verfolgt. Über die Möglichkeit der Spinellbildung des Systems wird diskutiert.

X‐ray and Electric Measurements on the HgCr2(SexS1–x)4 System

Abstract. In the HgCr2(SexS1–x)4 system there is no spinel structure in the 0.20 < x < 0.75 concentration range. In the miscibility gap the formation of HgSe and Cr283–ySey mixed crystals has been noticed. The lattice constants of the spinel solid solutions obey Végard's law only on the selenium‐rich side of the phase diagram. Both the temperature dependence of electric conductivity and the thermal analysis of the starting mixtures were studied. The possibility of formation of spinels in the system is discussed.
Nickel(II) Complexes of 1‐Phenyl‐5‐Methyl‐2,4‐Dithiobiuret
Authors: Pignedoli A. , Peyronbl G.
Published: January 2011

The following nickel(II) complexes of l‐phenyl‐6‐methyl‐2,4‐dithiobiuret (HL) have been prepared: NiL2, Ni(HL)2X2 (X = Cl, Br, I, ClO4, NO3, 1/2 SO4(3 H2O), CHCl2COO, CCl3COO). All the complexes are diamagnetic and have a square‐planar [NiS4] coordination. Strong ionic interactions occur in DMF solution between the cationic complex Ni(HL)2++ and some anions (Cl–, CHCl2COO–, CCl3COO–). The [NiS4] chromophores of the neutral and the cationic complexes show the same infrared spectra in the solid state and the same electronic spectra in solution independently from the associated anion. The orbital parameter δ1 locates the ligand in the spectrochemical series near the dithioacetylacetonate.

Nickel(II) Komplexe mit 1‐Phenyl‐5‐methyl‐2.4‐dithiobiuret

Inhaltsübersicht. Von l‐Phenyl‐5‐methyl‐2.4‐dithiobiuret (HL) wurden mit Nickel folgende Komplexe hergestellt: NiL2, Ni(HL)2X2 (X = Cl, Br, J, ClO4, NO3, 1/2 SO4 · 3 H2O, CHCl2CO2, CCl3CO2). Alle Komplexe sind diamagnetisch und besitzen die planare [NiS4]‐Anordnung. In den Verbindungen [Ni(HL)2]2+X22– mit X = Cl–, CHCl2CO2– und CCl3CO2– werden starke ionische Wechselwirkungen angenommen. Die IR‐ und Elektronenspektren sind für alle Verbindungen gleich, unabhängig vom Anion. Der Ligand steht in der spektrochemischen Reihe nahe dem Dithioacetyl‐acetonat.
Darstellung und Schwingungsspektren von F3SiAs(CH3)2 und F3SiP(CH3)2
Authors: Demuth Von R.
Published: January 2011

Inhaltsübersicht. Verschiedene Methoden zur Darstellung von F3SiAs(CH3)2 und F3SiP(CH3)2 werden mitgeteilt und diskutiert. Die neuen Trifluorsilylverbindungen werden durch KMR‐ und IR‐Spektren sowie durch Umsetzung mit polaren Reaktanden charakterisiert, Die Schwingungsspektren des F3SiAs(CH3)2 werden mit Hilfe einer Normalkoordinatenanalyse näher untersucht.

Preparation and Vibrational Spectra of F3SiAs (CH3)2 and F3SiP(CH3)2

Various preparative routes for the synthesis of F3SiAs(CH3)2 and F3SiP(CH3)2 are discussed. The new trifluoro‐silyl compounds are characterized by n.m.r. and i.r. spectra as well as by the reaction with polar compounds. The vibrational spectra of F3SiAs(CH3)2 are investigated using a normal coordinate analysis.
Darstellung und Eigenschaften von Blei(lV)‐selenit, Pb(SeO3)2, und der Alkali‐triselenitoplumbate(IV), M2[Pb(SeO3)3])
Authors: Frydrych R.
Published: January 2011

Inhaltsübersicht. Blei(IV)‐acetat reagiert in wäßriger Essigsäure mit seleniger Säure zu Blei(IV)‐selenit, Pb(SeO3)2, welches unter geeigneten Versuchsbedingungen mit Alkaliselenitlösungen in die Alkalitriselenitoplumbate(IV), M2[Pb(SeO3)3] übergeführt werden kann (M = NH4, K, Rb, Cs). Die dargestellten Verbindungen sind kristallin.

Preparation and Properties of Lead(IV) Selenite, Pb(SeO3)2, and the Alkali Triselenito‐plumbates(IV), M2[Pb(SeO3)3]

Lead(IV) acetate reacts in aqueous acetic acid with selenious acid to yield lead(IV) selenite, Pb(SeO3)2. Using suitable conditions of preparation lead(IV) selenite reacts with alkali‐selenites to yield alkali triselenito‐plumbates(lV). M2[Pb(SeO3)3]. All the prepared compounds are cristalline.
An abattoir-based study of hydatidosis in the dromedary (Camelus dromedarius) in Mashhad, Iran
Authors: Borji H. , Azizzadeh M. , Afsai A.
Published: January 2011

A 6-year retrospective study based on abattoir records was carried out to determine the prevalence of hydatidosis in dromedaries in Khorasan province in north–eastern Iran. Between 20 March 2004 and 19 March 2010, 25,255 dromedaries were slaughtered in the study area and the livers of 2791 (11.1%) and the lungs of 3289 dromedaries (13.2%) were discarded due to hydatidosis. The annual prevalence of liver condemnations due to hydatidosis decreased from 24.1% in 2004–2005 to 13.3% in 2009, and finally to 6.8% in 2010. The corresponding features for lung condemnation due to hydatidosis were relatively higher than liver, declining from 28.7% in 2004–2005 to 14.9% in 2009, and finally to 7.1% in 2010. Liver and lung condemnations due to hydatidosis were significantly higher in the spring. This could be attributed to various factors such as sources of slaughtered animals, changes in management practice and ecological factors. The present survey provides baseline data for the future monitoring of this potentially important parasitic disease in the region.
Purification and identification of endogenous polySUMO conjugates
Authors: Bruderer Roland , Tatham Michael H , Plechanovova Anna , Matic Ivan , Garg Amit K , Hay Ronald T
Published: January 2011

The small ubiquitin‐like modifier (SUMO) can undergo self‐modification to form polymeric chains that have been implicated in cellular processes such as meiosis, genome maintenance and stress response. Investigations into the biological role of polymeric chains have been hampered by the absence of a protocol for the purification of proteins linked to SUMO chains. In this paper, we describe a rapid affinity purification procedure for the isolation of endogenous polySUMO‐modified species that generates highly purified material suitable for individual protein studies and proteomic analysis. We use this approach to identify more than 300 putative polySUMO conjugates from cultured eukaryotic cells.
Molecular breeding of healthy vegetables
Authors: Goldman Irwin L
Published: January 2011

Breeders and plant scientists are increasing their efforts to raise the health benefits of fruits and vegetables. Yet, the positive impact of this on public health, it is not a substitute for a healthy diet.
Rotational spectra and equilibrium structures of H2SiS and Si2S
Authors: McCarthy Michael C. , Gottlieb Carl A. , Thaddeus Patrick , Thorwirth Sven , Gauss Jürgen
Published: January 2011

The rotational spectra of two small silicon sulfides, silanethione H \documentclass[12pt]{minimal}\begin{document}$_2$\end{document}2SiS and the disilicon sulfide ring Si \documentclass[12pt]{minimal}\begin{document}$_2$\end{document}2S, have been detected in the centimeter band by Fourier transform microwave spectroscopy of a molecular beam; lines of H \documentclass[12pt]{minimal}\begin{document}$_2$\end{document}2SiS were also observed in the millimeter band up to 377 GHz in a glow discharge. Precise rotational and centrifugal distortionconstants have been determined for the normal and a number of the more abundant rare isotopic species of both closed-shell molecules. Theoretical equilibrium ( \documentclass[12pt]{minimal}\begin{document}$r_e$\end{document}re) structures of H \documentclass[12pt]{minimal}\begin{document}$_2$\end{document}2SiS and Si \documentclass[12pt]{minimal}\begin{document}$_2$\end{document}2S were derived from coupled-cluster calculations that included triple and quadruple excitations, core correlation, and extrapolation to the basis-set limit. The \documentclass[12pt]{minimal}\begin{document}$r_e$\end{document}re structures agree to within \documentclass[12pt]{minimal}\begin{document}$5 \times 10^{-4}$\end{document}5×10−4 Å and \documentclass[12pt]{minimal}\begin{document}$0.1^\circ$\end{document}0.1∘with empirical equilibrium ( \documentclass[12pt]{minimal}\begin{document}$r_e^{\rm emp}$\end{document}re emp ) structures derived from the experimental rotational constants, combined with theoretical vibrational and electronic corrections. Both H \documentclass[12pt]{minimal}\begin{document}$_2$\end{document}2SiS and Si \documentclass[12pt]{minimal}\begin{document}$_2$\end{document}2S are good candidates for radioastronomical detection in the circumstellar shells of evolved carbon-rich stars such as IRC+10216, because they are fairly polar and are similar in composition to the abundant astronomical molecule SiS.
Non-Markovian quantum state diffusion for absorption spectra of molecular aggregates
Authors: Roden Jan , Strunz Walter T. , Eisfeld Alexander
Published: January 2011

In many molecular systems one encounters the situation where electronic excitations couple to a quasi-continuum of phonon modes. The interaction to that often structured continuum may be highly frequency dependent, e.g. due to some weakly damped high frequency modes. To handle such a situation, an approach combining the non-Markovian quantum state diffusion description of open quantum systems with an efficient but abstract approximation was recently applied to calculate energy transfer and absorption spectra of molecular aggregates [J. Roden, A. Eisfeld, W. Wolff, W. T. Strunz, Phys. Rev. Lett. 103, 058301 (2009)]. To explore the validity of the used approximation for such complicated systems, in the present work we compare the calculated (approximative) absorption spectra with exact results. These are obtained from the method of pseudomodes, which we show to be capable of determining the exact spectra for small aggregates and a few pseudomodes. It turns out that in the cases considered, the results of the two approaches mostly agree quite well. The advantages and disadvantages of the two approaches are discussed.
Electronic structure of the two isomers of the anionic form of p-coumaric acid chromophore
Authors: Zuev Dmitry , Bravaya Ksenia B. , Crawford T. Daniel , Lindh Roland , Krylov Anna I.
Published: January 2011

A theoretical study of the electronic structure of the photoactive yellow protein (PYP) model chromophore, para-coumaric acid (p-CA), is presented. Electronically excited states of the phenolate and carboxylate isomers of the deprotonated p-CA are characterized by high-level ab initio methods including state-specific and multistate multireference pertrubation theory (SS-CASPT2, and MS-CASPT2), equation-of-motion coupled-cluster methods with single and double substitutions (EOM-CCSD) and with an approximate account of triple excitations (CC3). We found that the two isomers have distinctly different patterns of ionization and excitation energies. Their excitation energies differ by more than 1 eV, in contradiction to the experimental report [Rocha-Rinza et al., J. Phys. Chem. A 113, 9442 (2009)]. The calculations confirm metastable (autoionizing) character of the valence excited states of both phenolate and carboxylate isomers of p-CA \documentclass[12pt]{minimal}\begin{document}$^-$\end{document}− in the gas phase. The type of resonance is different in the two forms. In the phenolate, the excited state lies above the detachment continuum (a shape resonance), whereas in the carboxylate the excited \documentclass[12pt]{minimal}\begin{document}$\pi \rightarrow \pi ^*$\end{document}π→π* state lies below the π-orbital ionization continuum, but is above the states derived from ionization from three other orbitals (Feshbach resonance). The computed oscillator strength of the bright electronic state in the phenolate is higher than in the carboxylate, in agreement with Hückel's model predictions. The analysis of photofragmentation channels shows that the most probable products for the methylated derivatives of the phenolate and carboxylate forms of p-CA \documentclass[12pt]{minimal}\begin{document}$^-$\end{document}− are CH \documentclass[12pt]{minimal}\begin{document}$_3$\end{document}3, CH \documentclass[12pt]{minimal}\begin{document}$_2$\end{document}2O and CH \documentclass[12pt]{minimal}\begin{document}$_3$\end{document}3, CH \documentclass[12pt]{minimal}\begin{document}$_2$\end{document}2O, CO \documentclass[12pt]{minimal}\begin{document}$_2$\end{document}2, respectively, thus suggesting an experimental probe that may discriminate between the two isomers.
Configurational temperature and local properties of the anisotropic Gay–Berne liquid crystal model: Applications to the isotropic liquid/vapor interface and isotropic/nematic transition
Authors: Ghoufi Aziz , Morineau Denis , Lefort Ronan , Malfreyt Patrice
Published: January 2011

Molecular simulations in the isothermal statistical ensembles require that the macroscopic thermal and mechanical equilibriums are respected and that the local values of these properties are constant at every point in the system. The thermal equilibrium in Monte Carlo simulations can be checked through the calculation of the configurational temperature, \documentclass[12pt]{minimal}\begin{document}$\displaystyle {k_BT_{\mathrm{conf}}={\langle |\nabla _r U({r}^N)|^{2}\rangle}/{\langle \nabla _r{^2} U({r}^N) \rangle}}$\end{document}kBT conf =⟨|∇rU(rN)|2⟩/⟨∇r2U(rN)⟩, where \documentclass[12pt]{minimal}\begin{document}$\nabla _r$\end{document}∇r is the nabla operator of position vector r. As far as we know, \documentclass[12pt]{minimal}\begin{document}$T_{{\rm conf}}$\end{document}T conf was never calculated with the anisotropic Gay–Berne potential, whereas the calculation of \documentclass[12pt]{minimal}\begin{document}$T_{{\rm conf}}$\end{document}T conf is much more widespread with more common potentials (Lennard Jones, electrostatic, …). We establish here an operational expression of the macroscopic and local configurational temperatures, and we investigate locally the isotropic liquid phase, the liquid / vapor interface, and the isotropic–nematic transition by Monte Carlo simulations.