bluuebunny/crossref_metadata_2025 huggingface dataset:
Emerging Pollutants as Endocrine Disruptors
Authors: Reis Filho Ricardo Wagner , Luvizotto-Santos R. , Vieira Eny Maria
Published: March 2010

Emerging pollutants, such as pharmaceutical products, natural and synthetic hormones, pesticides, tensoactive substances, low-molecular-mass polymers, veterinary products, solvents and other organic contaminants present in urban and industrial effluents may act as endocrine disruptors (ED). The presence of such chemical species in the biota can lead to reproductive dysfunction and studies have shown they may also cause cancer. For humans, despite the fact that conclusive cause-and-effect relations have not yet been established, several published papers have indicated that a wide range of disorders, such as inborn impairments, behavioral and neurological alterations, immune deficiency, accelerated puberty, quality of semen and cancers (thyroid, breast, ovary, prostate, testicles) can be credited to endocrine disruptors emerging pollutants. The problem is more accentuated in developing countries, where environmental legislation is often poor, out of date and, as result does not consider substances with endocrine disrupting potential. In addition, the lack of basic sanitation aggravates the situation. In Brazil, for instance, approximately 80% of urban centers do not have any form of sewage treatment. Consequently, emerging pollutants enter the ecosystem through several paths generating threat to biota and, because of this, it represent an area which requires urgent attention, discussion and management.
Reduced Form Credit Risk Models
Authors: Jarrow Robert A. , Van Deventer Donald R.
Published: March 2010

Reduced form credit risk models focus on modeling the probability of default rather than trying to explain default in terms of the firm's asset value. The review is focused on models based on Cox processes. Topics discussed include debt valuation, default contagion, risk management, the valuation of credit derivatives, and frailty.
L
ibor Market Model
Authors: Andersen Leif B.G. , Piterbarg Vladimir V.
Published: March 2010

This article presents the
Libor market model
for interest‐rate dynamics. We discuss the specification of the model, its dynamics under various measures of interest, approximations for European option pricing, calibration, and numerical methods for securities valuation.
Copulas in Insurance
Authors: Chavez‐Demoulin Valérie , Embrechts Paul
Published: March 2010

The modeling of dependence has increasingly become one of the key issues in insurance. We highlight the use as well as the misuse of the concept of copula in this context. The main themes are the use of copula methodology in quantitative risk management and actuarial ruin theory.
Fundamental Principles of Quantum Dots
Authors: Parak Wolfgang J. , Manna Liberato , Nann Thomas
Published: March 2010

Quantum dots are intermediates between atoms/molecules and bulk material. Therefore they can be described either by upscaling the concepts of atoms/molecules or by downscaling the concepts of bulk materials. This allows for understanding size‐dependent properties, as in particular the size‐dependent wavelength of fluorescence.
Organocatalytic Asymmetric Michael Addition of Pyrazolin‐5‐ones to Nitroolefins with Bifunctional Thiourea: Stereocontrolled Construction of Contiguous Quaternary and Tertiary Stereocenters
Authors: Liao Yu‐Hua , Chen Wen‐Bing , Wu Zhi‐Jun , Du Xi‐Lin , Cun Lin‐Feng , Zhang Xiao‐Mei , Yuan Wei‐Cheng
Published: March 2010

The first organocatalytic diastereo‐ and enantioselective Michael addition reaction of 4‐substituted‐pyrazolin‐5‐ones to nitroolefins has been developed with a chiral bifunctional thiourea as organocatalyst. A wide variety of desired multi‐substituted pyrazolin‐5‐one derivatives with contiguous quaternary and tertiary stereocenters are smoothly obtained in very good yields (up to 98%) with excellent enantioselectivities (up to>99%ee) and acceptable diastereoselectivities (up to 80:20). This experimentally simple process facilitates the access to various enantioenriched, multiply substituted pyrazolin‐5‐one derivatives, potential biologically active molecules, starting from readily available starting materials.
Inhibitors of Human Histone Deacetylase: Synthesis and Enzyme Assay of Hydroxamates with Piperazine Linker
Authors: Chakrabarty Shubhashis , Jasmine  , Bhadaliya Chetan , Nayan Sinha Barij , Mahesh Aruna , Bai He , Blond Sylvie Y. , Jayaprakash Venkatesan
Published: March 2010

The histone deacetylase (HDAC) enzyme plays an important role in gene transcription. Inhibitors of histone deacetylases induce cell differentiation and suppress cell proliferation in tumor cells. Hydroxamates with rigid linker have displayed better inhibition profiles than those with linear and flexible aliphatic linkers. We have designed and synthesized several potential histone deacetylase inhibitors with a piperazine moiety in the linker region to test the effect of reduced linker flexibility. Inhibitors were evaluated for their inhibitory action on human HDAC3/NCoR2 and HDAC8. N‐Hydroxycarboxamide derivatives (compounds 4a–d) were found to be better than N‐hydroxyacetamide derivatives (compounds 6a–d) against HDAC8. Amongst the synthesized compounds, 4a (HDAC8, IC50: 3.15 μM) with no substitution in the aryl cap was the most active and promising lead for further investigations.
Building artificial cells and protocell models: Experimental approaches with lipid vesicles
Authors: Walde Peter
Published: March 2010

Lipid vesicles are often used as compartment structures for preparing cell‐like systems and models of protocells, the hypothetical precursor structures of the first cells at the origin of life. Although the various artificially made vesicle systems are already remarkably complex, they are still very different from and much simpler than any known living cell. Nevertheless, the preparation and study of the structure and the dynamics of functionalized vesicle systems may contribute to a better understanding of biological cells, in particular of the essential features of a living cell that are not found in the non‐living form of matter. The study of protocell models may possibly lead to a better understanding of the origin of the first cells. To avoid misunderstanding in this field of research, it would be useful if generally accepted definitions of terms like “artificial cells,” “synthetic cells,” “minimal cells,” “protocells,” and “primitive cells” exist.

 

Editor's suggested further reading in BioEssays

Synthetic cells and organelles: compartmentalization strategiesAbstract
Xenobiology: A new form of life as the ultimate biosafety tool
Authors: Schmidt Markus
Published: March 2010

Synthetic biologists try to engineer useful biological systems that do not exist in nature. One of their goals is to design an orthogonal chromosome different from DNA and RNA, termed XNA for xeno nucleic acids. XNA exhibits a variety of structural chemical changes relative to its natural counterparts. These changes make this novel information‐storing biopolymer “invisible” to natural biological systems. The lack of cognition to the natural world, however, is seen as an opportunity to implement a genetic firewall that impedes exchange of genetic information with the natural world, which means it could be the ultimate biosafety tool. Here I discuss, why it is necessary to go ahead designing xenobiological systems like XNA and its XNA binding proteins; what the biosafety specifications should look like for this genetic enclave; which steps should be carried out to boot up the first XNA life form; and what it means for the society at large.
Nickel(II) Nitrate vs. Acetate: Influence of the Precursor on the Structure and Reducibility of Ni/MCM‐41 and Ni/Al‐MCM‐41 Catalysts
Authors: Marceau Eric , Che Michel , Čejka Jiří , Zukal Arnošt
Published: March 2010

Nickel(II) nitrate is the nickel precursor generally selected to prepare oxide‐supported catalysts, due to its low cost, high solubility in water and decomposition at moderate temperatures. However, its decomposition produces NOx, and it is known to melt and redistribute over the support upon heating, leading to poorly dispersed metal particles after reduction and to their partial expulsion from the porous support system. The benefits of using NiII acetate as an alternative to NiII nitrate are explored by investigating a series of model Ni catalysts (1–5 wt %) prepared from the mesoporous siliceous supports MCM‐41 and Al‐MCM‐41. The problems encountered with NiII nitrate, in terms of particle size and redistribution of nickel, are not observed with NiII acetate. In the case of MCM‐41‐supported systems, metal particles are well dispersed and remain located within the porous support. The higher pH of the impregnation solution, favoring electrostatic interactions between nickel ions and the support, may account for the higher metal dispersion. The formation of silicate‐like species in strong interaction with the support does not appear prominent on siliceous MCM‐41 when nickel acetate is the precursor, but seems to be enhanced for higher Ni contents. Finally, Al‐MCM‐41 supports are more sensitive to the exposure to nickel acetate than their siliceous analogues because acetate ions are able to extract Al ions from the support, resulting in a partial disruption of the support organization and to the formation of nickel silicate species.
Theoretical Characterization of Charge Transport in One‐Dimensional Collinear Arrays of Organic Conjugated Molecules
Authors: Viani Lucas , Olivier Yoann , Athanasopoulos Stavros , da Silva Filho Demetrio A. , Hulliger Jürg , Brédas Jean‐Luc , Gierschner Johannes , Cornil Jérôme
Published: March 2010

A great deal of interest has recently focused on host–guest systems consisting of one‐dimensional collinear arrays of conjugated molecules encapsulated in the channels of organic or inorganic matrices. Such architectures allow for controlled charge and energy migration processes between the interacting guest molecules and are thus attractive in the field of organic electronics. In this context, we characterize here at a quantum‐chemical level the molecular parameters governing charge transport in the hopping regime in 1D arrays built with different types of molecules. We investigate the influence of several parameters (such as the symmetry of the molecule, the presence of terminal substituents, and the molecular size) and define on that basis the molecular features required to maximize the charge carrier mobility within the channels. In particular, we demonstrate that a strong localization of the molecular orbitals in push–pull compounds is generally detrimental to the charge transport properties.
Multiferroic Domain Boundaries as Active Memory Devices: Trajectories Towards Domain Boundary Engineering
Authors: Salje Ekhard K. H.
Published: March 2010

Twin boundaries in ferroelastics and curved interfaces between crystalline and amorphous zircon can, in principle, act as multiferroic structural elements and lead the way to the discovery of novel multiferroic devices which are based on structurally heterogeneous materials. While this paradigm has not yet been explored in full, this review shows that physical and chemical properties can vary dramatically inside twin boundaries and interfaces. Properties that have been already been explored include electric dipoles in a non‐polar matrix, the appearance of superconductivity in twin boundaries and the catalytic reaction of hydrous species in interfaces of radiation damaged material. Some of the fundamental physical and chemical properties of twin boundaries and related interfaces are described and possible applications are outlined.
In Situ Characterization of Thermo‐Responsive Poly(N‐Isopropylacrylamide) Films with Sum‐Frequency Generation Spectroscopy
Authors: Kurz Volker , Grunze Michael , Koelsch Patrick
Published: March 2010

The thermo‐responsive behaviour of thiol modified poly(N‐isopropylacrylamide) (pNIPAM) films immobilized on gold are probed by in situ broadband sum‐frequency generation (SFG) spectroscopy. The pNIPAM films were prepared by atom transfer radical polymerization (ATRP) using a nitro‐biphenyl‐thiol (NBT)‐SAM on a polycrystalline gold surface as a substrate. Additionally, Raman and infrared reflection absorption spectroscopy (IRRAS) are applied to spin‐coated pNIPAM films. Molecular groups involved in the reorientation and disordering of the polymer chains during the LCST (lower critical solution temperature) transition of pNIPAM are identified. The characteristic vibrations of the CH3 groups show a gradual reorientation of the isopropyl groups within the pNIPAM film and instantaneous reorientation of the outermost CH3 groups around 32 °C.
Synthesis of Dicarbonylruthenium(II) Complexes of Functionalized P,S‐Chelating Diphosphane Ligands and Their Catalytic Transfer Hydrogenation
Authors: Deb Biswajit , Sarmah Podma Pollov , Dutta Dipak Kumar
Published: March 2010

The reaction of P,S‐chelating diphosphane ligands [bis(2‐diphenylphosphanylphenyl)ether monosulfide] (a) and [9,9‐dimethyl‐4,5‐bis(diphenylphosphanyl)xanthene monosulfide] (b) with [Ru(CO)2Cl2]n in a 1:1 molar ratio affords two new ruthenium(II) complexes of the type [Ru(CO)2Cl2(P∩S)] (1a, 1b), where P∩S = a, b. The compounds are characterized by elemental analyses, mass spectrometry, thermal studies, and IR and NMR spectroscopy, together with single‐crystal X‐ray structure determination of bis(2‐diphenylphosphanylphenyl)ether (DPEphos), a, 1a, and 1b. The ruthenium atom in both 1a and 1b occupies the center of a slightly distorted octahedral environment formed by a P atom, an S atom, two Cl atoms, and two CO groups. The crystal structures of a and 1a highlights an interesting feature, in which the P(2)–P(1)–S(1) spatial angle (ca. 174.7°) in free ligand a is reduced to around 46° upon complexation, which indicates a very high flexibility of the angle. Complex 1a also exhibits some hemilabile behavior in solution because of its flexible ligand backbone, while ligand b in complex 1b remains rigid in solution. Complexes 1a and 1b are thermally stable up to about 300 °C and show high catalytic activities in the transfer hydrogenation of aldehydes and ketones to the corresponding alcohols. The highest conversion (about 99 %) with the corresponding TOF value of about 1000 h–1 was obtained for 1a in the case of benzaldehyde. The catalytic efficiency of 1a is found to be much higher than 1b, which might result from the hemilabile behavior of ligand a.
Square‐Planar 2‐Toluenido(triphenylphosphane)nickel(II) Complexes Containing Bidentate N,O Ligands: An Example of Planar Chirality
Authors: Beckmann Udo , Hägele Gerhard , Frank Walter
Published: March 2010

Nickel(II) complexes comprising electronically delocalised N,O‐chelating ligands are active catalysts in the copolymerisation of carbon monoxide and ethene. Elucidating the mechanism of catalysis presupposes the basic understanding of the intramolecular flexibility of such transition metal complexes. Several nickel(II) complexes with or without planar chirality were synthesised and characterised by NMR spectroscopic techniques and X‐ray diffraction.
Heteroleptic Guanidinate‐ and Amidinate‐Based Complexes of Hafnium as New Precursors for MOCVD of HfO2
Authors: Xu Ke , Milanov Andrian P. , Winter Manuela , Barreca Davide , Gasparotto Alberto , Becker Hans‐Werner , Devi Anjana
Published: March 2010

The synthesis and characterization of four new heteroleptic complexes [Hf{η2‐(iPrN)2CNMe2}2Cl2] (1), [Hf{η2‐(iPrN)2CNMe2}2Me2] (2), [Hf{η2‐(iPrN)2CMe}2Cl2] (3), and [Hf{η2‐(iPrN)2CMe}2Me2] (4) are reported. All the complexes were characterized by spectroscopic methods, while compounds 1–3 were further examined by single‐crystal X‐ray diffraction, revealing that the complexes are monomers with the hafnium center in a distorted octahedral geometry. The thermal properties of the chlorine‐free complexes (2, 4) were examined to determine their suitability for metalorganic chemical vapor deposition (MOCVD) applications, and compound 2 showed good volatility and thermal stability. On the basis of these results, compound 2 was selected for MOCVD of HfO2 with oxygen as oxidant. Depositions were carried out on Si(100) substrates in the temperature range 300–700 °C. The as‐deposited HfO2 films crystallized in the monoclinic phase at temperatures above 500 °C, and the composition analysis determined by Rutherford back‐scattering (RBS) and X‐ray photoelectron spectroscopy (XPS) revealed that the films were stoichiometric and free of carbon. Thus, alkylguanidinatohafnium complex 2 is a promising precursor for growing HfO2 films in a wide temperature range with the desired stoichiometry, because of its adequate volatility, sufficient temperature window between vaporization and decomposition, as well as its ability to decompose cleanly in the presence of oxygen.
Synthesis of Heterocycles by Intramolecular Nucleophilic Substitution at an Electron‐Deficient sp2 Nitrogen Atom
Authors: Sączewski Jarosław , Gdaniec Maria
Published: March 2010

2‐Aryl(arylsulfonyl)‐6,7‐dihydro‐2H‐imidazo[2,1‐c][1,2,4]triazol‐3(5H)‐ones and 3‐arylimino‐6,7‐dihydroimidazo[2,1‐c][1,2,4]thiadiazoles have been synthesized by intramolecular nucleophilic substitution reactions at the electron‐deficient sp2 nitrogen atom of 2‐(hydroxyimino)imidazolidine O‐sulfonate. The displacement of the sulfate leaving group by both nitrogen and sulfur anionic nucleophiles proceeds exothermically by in‐plane SN2σ nucleophilic substitution.
Pd‐Promoted Homocoupling Reactions of Unsaturated Silanes in Aqueous Micelles
Authors: Cicco Stefania R. , Farinola Gianluca M. , Martinelli Carmela , Naso Francesco , Tiecco Matteo
Published: March 2010

Palladium‐promoted homocoupling reaction of vinyl‐ andpolyenylsilanes in aqueous conditions has been investigated. The reaction is catalyzed by PdCl2 in the presence of the reoxidizing system CuCl2/LiCl and occurs at room temperature in aqueous solutions containing nonionic amphiphiles. Symmetrically α,ω‐disubstituted stereodefined all‐trans polyenes have been obtained in mild conditions and in good yields (65–87 %), higher than those previously reported for the same reactions carried out in methanol or HMPA. A comparison between two commercially available surfactants, Triton X‐100 and PTS, has been performed.
Palladium‐Catalyzed Multialkynyl Cross‐Coupling Reactions with Tetraalkynylindates
Authors: Kang Dongjin , Eom Dahan , Kim Hyunseok , Lee Phil Ho
Published: March 2010

An efficient Pd‐catalyzed multialkynyl cross‐coupling reaction performed with tetraalkynylindates generated in situ from the reaction of 1 equiv. of indium trichloride with 4 equiv. of organometallic reagents has been developed to produce symmetric as well as unsymmetric multialkynyl‐substituted aromatic compounds in good‐to‐excellent yields. In these reactions, the four acetylide groups in the tetraalkynylindates transferred effectively to a variety of aryl bromides.
Photomicrobial Solar and Fuel Cells
Authors: Rosenbaum Miriam , Schröder Uwe
Published: March 2010

Microbial solar cells and photomicrobial fuel cells exploit the energy of light and the activity of phototrophic microorganisms to produce electricity. Whereas microbial solar cells use light as the sole energy source, photomicrobial fuel cells degrade organic matter in the presence of light. This review gives an overview about the recent developments in the field of microbial based photobiological fuel cells and microbial solar cells. It provides an insight into possible electron transfer mechanisms and elementary photobiological reaction pathways. A short outline of upcoming engineering issues is provided.
Voltammetry and Growth Physiology of Geobacter sulfurreducens Biofilms as a Function of Growth Stage and Imposed Electrode Potential
Authors: Marsili Enrico , Sun Jian , Bond Daniel R.
Published: March 2010

The ability of Geobacter sulfurreducens to utilize electrodes as electron acceptors provides a system for monitoring mechanisms of electron transfer beyond the cell surface. This study examined the physiology of extracellular electron transfer during many stages of growth, and in response to short‐ and long‐term changes in electron acceptor potential. When G. sulfurreducens was grown on planar potentiostat‐controlled electrodes, the magnitude of early cell attachment increased with initial cell density. However, the first cells to attach did not demonstrate the same electron transfer rates as cells grown on electrodes. For example, following initial attachment of fumarate‐grown cells, the electron transfer rate was 2 mA/mg protein, but increased to nearly 8 mA/mg protein within 6 h of growth. Once attached, all biofilms grew at a constant rate (doubling every 6 h), and sustained a high specific electron transfer rate and growth yield, while current density was below 300 μA/cm2. Beyond this point, the rate of current increase slowed and approached a stable plateau. At all phases, slow scan rate cyclic voltammetry of G. sulfurreducens showed a similar well‐defined sigmoidal catalytic wave, indicating the general model of electron transfer to the electrode was not changing. Short‐term exposure to reducing potentials (3 h) did not alter these characteristics, but did cause accumulation of electrons which could be discharged at potentials above −0.1 V. Sustained growth at lower potentials (−0.16 V) only slightly altered the pattern of detectable redox species at the electrode, but did eliminate this pattern of discharge from the biofilm. Single‐turnover voltammetry of colonized electrodes showed at least 3 redox couples at potentials similar to other recent observations, with redox protein coverage of the electrode on the order of ca. 1 nmol/cm2. The consistent electrochemistry, growth rate, and growth yield of the G. sulfurreducens biofilm at all stages suggests an initial phase where cells must optimize attachment or electron transfer to a surface, and that after this point, the rate of electron production by cells (rate electrons are delivered to the external surface) remains rate limiting compared to the rate electrons can be transferred between cells, and to electrodes.
Glucose Oxidase Catalyzed Self‐Assembly of Bioelectroactive Gold Nanostructures
Authors: Luckarift Heather R. , Ivnitski Dmitri , Rincón Rosalba , Atanassov Plamen , Johnson Glenn R.
Published: March 2010

Glucose oxidase catalyzes the formation of metallic gold particles in immediate proximity of the protein from gold (III) chloride in the absence of any other catalytic or reductive substrates. The protein‐mediated gold reduction reaction leads to size‐controllable gold particle formation and concomitant association of the enzyme in an electrically conductive metallic template. Such an enzyme immobilization strategy provides a simple and rapid method to create an intimate interface between glucose oxidase and a conductive matrix, which can be joined to an electrode surface. Model electrodes were prepared by entraining the glucose oxidase/gold particles onto carbon paper. Voltammetry of the resulting electrodes revealed stable oxidation and reduction peaks at a potential close to that of the standard value for the FAD/FADH2 cofactor of immobilized glucose oxidase. The gold electrodes exhibit catalytic activity in the presence of glucose confirming the entrapment of active glucose oxidase within the gold architecture. The resulting composite material can be successfully integrated with electrodes of various designs for biosensor and biofuel cell applications.
Toxic hazard of leachates from furfurylated wood: Comparison between two different aquatic organisms
Authors: Pilgård Annica , De Vetter Liesbeth , Van Acker Joris , Westin Mats
Published: March 2010

Environmental concern regarding the use of toxic preservatives such as chromated copper arsenate (CCA) has been put forward. In the European Union, United States, and Japan, CCA has been phased out for residential and water-contact applications. Ecotoxicological studies of wood treated with conventional preservatives were carried out in the late 1990s, and it was concluded that the main impact is to water and aquatic organisms. Today, alternatives to conventional preservation methods, marketed as “environmentally friendly” or “nontoxic,” are emerging. Examples of such alternatives are modified wood, e.g., thermally modified, furfurylated, and acetylated wood. To date, not enough hazard characterization has been performed. In the present study, the Microtox® assay with the marine bacterium Vibrio fischeri and the Daphtox® procedure with the crustacean Daphnia magna were used as screening methods in an effect assessment. Both organisms were exposed to water leachates from furfurylated wood using two different leaching procedures. The results indicate that Microtox is more sensitive to the toxic components from furfurylated wood than Daphtox. Furthermore, the toxicity of treated Pinus radiata was higher than that of treated Pinus sylvestris. The toxicity did not diminish over the test period, as is the case for preservative-treated wood. The present study found that treatment conditions can influence the toxicity considerably, so toxicity studies should be included in the development of new treatment process. The present study also shows that using an intermediate vacuum-drying step, leading to a more efficient curing/polymerization, results in slightly less hydrophobic oligomers in the product, such that the leachates become less toxic to bacteria. Environ. Toxicol. Chem. 2010;29:1067–1071. © 2010 SETAC
Retrospective evaluation of revised criteria for the diagnosis of Alzheimer's disease using a cohort with post‐mortem diagnosis
Authors: de Jager Celeste A , Honey Thurza EM , Birks Jacqueline , Wilcock Gordon K
Published: March 2010

Objective

The criteria currently used to diagnose Alzheimer's disease (AD) require the presence of dementia, i.e. cognitive impairment sufficient to affect normal social and/or occupational function. Dubois et al. (Dubois et al., 2007) have recently proposed a set of revised criteria that may aid the diagnosis of the earlier stages of AD, and do not require the presence of dementia. We aimed to evaluate the new predementia‐AD criteria through their retrospective application to the OPTIMA cohort with post‐mortem (PM) confirmed diagnoses.

Methods

The criteria were evaluated for sensitivity and specificity using cognitive, neuroimaging and cerebrospinal fluid data and clinical information for exclusion criteria. Limitations in choice of cognitive test, use of CT scans rather than MRI and missing CSFs affected the outcomes. Analyses were carried out for the whole cohort (n = 243) and on a mild‐stage subgroup (n = 99) defined by MMSE ≥ 21.

Results

Of the four options for fulfilling the revised‐criteria, the best results for the whole cohort were achieved using memory and CSF data with exclusion criteria applied (.68 sensitivity and .93 specificity). The pattern was similar for the mild cohort, but with lower sensitivity. Specificities of 1.0 were reached with supportive criteria, CSF and CSF plus MTL.

Conclusions

The revised‐criteria, when applied to our cohort, offer good specificity and reasonable sensitivity when compared with the gold standard of PM diagnosis. The criteria were not more effective for early stage dementia. Copyright © 2010 John Wiley & Sons, Ltd.
The effect of femoral component rotation on the extensor retinaculum of the knee
Authors: Ghosh Kanishka M. , Merican Azhar M. , Iranpour Farhad , Deehan David J. , Amis Andrew A.
Published: March 2010

Malrotation of the femoral component may cause patellofemoral complications after total knee replacement (TKR). We hypothesized that femoral component malrotation would cause excessive lengthening of the retinacula. Retinacular length changes were measured by threading fine sutures along them and attaching these to the patella and to displacement transducers. The knee post‐TKR was flexed‐extended while the quadriceps were tensed, then the measurements repeated after rotating the femoral component 5° internally and then 5° externally. Internal rotation shortened the medial patellofemoral ligament (MPFL) significantly from 100° to 0° extension. External rotation lengthened the MPFL significantly from 90° to 0° extension. The transverse fibers of the lateral retinaculum showed no significant differences. The MPFL attaches directly from bone to bone, so it was lengthened directly by movement of the trochlea and patella, whereas the deep transverse fibers of the lateral retinaculum attach to the mobile iliotibial tract, so they were not lengthened directly. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1136–1141, 2010
Metal‐assisted regioselectivity in nucleophilic substitutions: a study by Raman spectroscopy and density functional theory calculations
Authors: Defant Andrea , Rossi Barbara , Viliani Gabriele , Guella Graziano , Mancini Ines
Published: March 2010

A series of complexes (FeII, CuII and NiII) of the N,O bidentate ligand 6,7‐dichloroquinoline‐5,8‐dione in water was investigated by using Raman spectroscopy, and the experimental peaks were assigned with the help of computed spectra by density functional theory (DFT) calculations. A strong shift to lower wavenumbers was observed for the vibration of the CO group involved in chelation, depending on the type of metal ion. When each complex was used in the substitution reaction by the nucleophilic reagent piperidine, two products having the same molecular composition but showing the substituent in different regions of the molecule were obtained, and moreover their regioselective formation was in agreement with the size of the Raman shifts previously observed for the complexes. This example confirms the potential of the approach involving Raman spectroscopy combined with DFT calculations in the characterization of metal complexes as key intermediates in organic reactions, with the possibility of predicting the metal system capable to achieve the highest selectivity. Copyright © 2010 John Wiley & Sons, Ltd.
Comparative post‐harvest behaviour of traditional and virus‐resistant Muchamiel tomatoes
Authors: Alonso Arantxa , García‐Martínez Santiago , Vázquez‐Araújo Laura , Ruiz Juan J , Carbonell‐Barrachina Ángel A
Published: March 2010

BACKGROUND: Nowadays, organoleptic quality is the primary objective for almost all tomato breeding programmes. In this study, post‐harvest behaviour of a breeding line with genetic resistance to important viruses (tomato mosaic virus, tomato spotted wilt virus and tomato yellow leaf curl virus) has been compared with the original traditional landrace (Muchamiel). The breeding line has been obtained by backcrossing, introgressing three resistance genes but aiming to keep the quality characteristics of the traditional variety. Tomatoes were picked at random and stored at 10 °C for 13 days. Quality analyses were made in both tomato samples: weight loss, colour, respiration rate, ethylene production, maturity index, instrumental hardness and sensory evaluation with trained panel.

RESULTS: Fruits of the breeding line were characterized by higher hardness even with a higher maturity index. Results of sensory tests were in agreement with instrumental measurements. Organoleptic quality of Muchamiel virus‐resistant tomatoes was at least as high as that of traditional tomatoes, reaching the best scores in odour and aroma at the 13th storage day.

CONCLUSION: Although a long time has been required to develop the breeding line, results indicate that organoleptic fruit quality has been recovered through backcrossing, confirming the success of the breeding programme. Copyright © 2010 Society of Chemical Industry
Sensory properties and consumer acceptance of sweet tamarind varieties grown in Thailand
Authors: Oupadissakoon Chintana , Chambers IV Edgar , Kongpensook Varapha , Suwonsichon Suntaree , Yenket Renoo , Retiveau Annlyse
Published: March 2010

BACKGROUND: Sweet tamarind is a major edible fruit and flavoring ingredient particularly in south‐east and southern Asia. Little research has focused on the fruit and almost nothing is known of its particular sensory properties. The aims of this research were to develop a lexicon for describing sweet tamarind, to compare varieties grown in Thailand, determine if orchard impacts sensory properties, and determine consumer acceptance of the varieties.

RESULTS: A descriptive sensory lexicon of 25 terms was developed and six varieties were grouped into three clusters based on their sensory properties. The clusters appear to represent varieties that differ in their dark fruity notes and firm, fibrous texture. Generally, the orchard in which the plants were grown had little effect on sensory properties. In general, Sithong was liked by consumers along with Kunthee and Pragaithong. Intapalum was liked less but one small segment of consumers disliked Sithong and liked the Intapalum variety more.

CONCLUSIONS: This research provides a foundation for further sensory and consumer research on sweet tamarind varieties by providing the initial data on the sensory properties of sweet tamarind, a lexicon that can be used for future research, and information on the consumer acceptance of tamarind varieties. Copyright © 2010 Society of Chemical Industry
Quality of fresh‐cut baby spinach grown under a floating trays system as affected by nitrogen fertilisation and innovative packaging treatments
Authors: Rodríguez‐Hidalgo Stephanie , Artés‐Hernández Francisco , Gómez Perla A , Fernández Juan Antonio , Artés Francisco
Published: March 2010

BACKGROUND: Alternative techniques for cultivation of leafy vegetables such as a floating tray system and unconventional gas mixtures for post‐harvest active modified atmosphere packaging (MAP) could be of interest in the minimally processed vegetable industry.

RESULTS: The combined effect of three pre‐harvest fertilisation doses (8, 12 or 16 mmol N L−1) and three post‐harvest MAP conditions (passive, super‐atmospheric or N2O‐enriched) on the main quality attributes of fresh‐cut baby spinach leaves throughout 10 days at 5 °C was studied. After 8 days of shelf life, spinach leaves fertilised with 8 and 16 mmol N L−1 and stored under N2O‐enriched MAP showed the lowest microbial growth, with good sensory quality. Such combined treatments also preserved the total antioxidant capacity sampled at harvest (8 g ascorbic acid equivalent antioxidant capacity kg−1 f.w.). A decrease of 10–20% in total vitamin C content regardless of N fertilisation and packaging treatment was found during shelf life. Total phenolics content at harvest was 2 g gallic acid equivalents kg−1 f.w., which was slightly decreased or preserved during shelf life while total chlorophylls were preserved for all treatments assayed around 550 mg kg−1 f.w.

CONCLUSION: No clear effect of fertilisation doses was observed during post‐harvest storage on overall quality of fresh‐cut baby spinach leaves, while N2O‐enriched atmospheres seems to be a promising alternative to passive MAP for extending shelf life. Copyright © 2010 Society of Chemical Industry
Stabilization and Release of Enzymes from Silk Films
Authors: Lu Qiang , Wang Xiaoqin , Hu Xiao , Cebe Peggy , Omenetto Fiorenzo , Kaplan David L.
Published: March 2010

A significant challenge remains to protect protein drugs from inactivation during production, storage, and use. In the present study, the stabilization and release of horseradish peroxidase (HRP) in silk films was investigated. Water‐insoluble silk films were prepared under mild aqueous conditions, maintaining the activity of the entrapped enzyme. Depending on film processing and post‐processing conditions, HRP retained more than 90% of the initial activity at 4 °C, room temperature and 37 °C over two months. The stability of protein drugs in silk films is attributed to intermolecular interactions between the silk and the enzymes, based on Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The unique structural feature of silk molecules, periodic hydrophobic‐hydrophilic domains, enabled strong interactions with proteins. The entrapped protein was present in two states, untrapped active and trapped inactive forms. The ratio between the two forms varied according to processing conditions. Proteolytic degradation and dissolution of the silk films resulted in the release of the bound enzyme which was otherwise not released by diffusion; enzyme recovered full activity upon release. There was a linear relationship between silk degradation/dissolution and the release of entrapped enzyme. Modifying the secondary structure of the silk matrix and the interactions with the non‐crystalline domains resulted in control of the film degradation or dissolution rate, and therefore the release rate of the entrapped enzyme. Based on the above results, silk materials are an intriguing carrier for proteins in terms of both retention of activity and controllable release kinetics from the films.

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Solvent Manipulation of Liquid Crystal Order and Other Properties in Azo‐Containing Surfactomesogen/Poly(styrene sulfonate) Complexes
Authors: Zhang Qian , Bazuin C. Geraldine
Published: March 2010

Stoichiometric ionically bonded side‐chain polymer complexes of poly(styrene sulfonate) and quaternary ammonium‐functionalised azo‐containing surfactomesogens were exposed to controlled humidity atmosphere, to organic non‐solvents (acetone, THF, ethyl acetate) and to a good solvent (DMF) for the complex. This modifies or increases the packing order, and includes induction of a crystal‐like lamellar structure that is amenable to photoisotropisation. The molecular packing order influences photoinduced birefringence relaxation. Conditions for frozen‐in morphologies are discussed in the light of higher temperature data. The observed diversity of phase changes upon solvent exposure is comparable to what is observed in surfactant–polyelectrolyte complexes.

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A Completely Biodegradable Poly[(L‐lactide)‐co‐(ε‐caprolactone)] Elastomer Reinforced by in situ Poly(glycolic acid) Fibrillation: Manufacturing and Shape‐Memory Effects
Authors: Wang Lian‐Song , Chen He‐Chun , Xiong Zuo‐Chun , Pang Xiu‐Bing , Xiong Cheng‐Dong
Published: March 2010

A new completely biodegradable shape‐memory elastomer consisting of PLLCA reinforced by in situ PGA fibrillation is described. The manufacturing processes and shape‐memory effects of the composites are discussed. DMA results reveal a strong interface interaction between in situ PGA fibrillation and PLLCA. Compared with the SMP‐based composites that are commonly used, the shape‐memory test shows that in situ PGA fibrillation can improve the recovery properties of PLLCA; in fact, the shape‐recovery rate increases from 80.5 to 93.2%.

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Synthesis of Aromatic Macrocyclic Amphiphiles and their Self‐Assembling Behavior in Aqueous Solution
Authors: Kim Jung‐Keun , Lee Eunji , Lee Myongsoo
Published: March 2010

A triblock amphiphilic macrocycle consisting of a macrocyclic aromatic segment, a hydrophilic oligo(ethylene oxide) branch, and a hydrophobic alkyl dendron is successfully synthesized and characterized. The resulting cyclic amphiphile is observed to self‐assemble into hollow double‐layered capsules in aqueous solution, as confirmed by dynamic light scattering and cryogenic transmission electron microscopy investigations. The capsules are able to encapsulate hydrophobic guest molecules through aromatic interactions with high stability.

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Organische Chemie 2009
Authors: Bräse Stefan
Published: March 2010

Organik von A wie Agrochemie bis Z wie (Solar‐)Zelle: die ersten Cycloadditionsreaktionen angeregter Photosubstrate, das erste Beispiel eines molekularen, schwarzen Porphyrins, ein neuer Weg zur Direktoxidation von Propen zu Propenoxid, die erste Totalsynthese des Haplophytins und vieles mehr.
Theoretische Chemie 2009
Authors: Berger Robert , Huh Joonsuk , Kleinekathöfer Ulrich , Ochsenfeld Christian
Published: March 2010

Fortschritte bei vibronischen Strukturmethoden ermöglichen Einblicke in Schwingungs‐ und Elektronenübergänge von Systemen mit Hunderten von Freiheitsgraden. Durch Kombination von klassischen und quantenmechanischen Zugängen in einem Multiskalenansatz lassen sich quantendynamische Prozesse in komplexen Systemen auf atomarer Skala simulieren. Mit linear‐skalierenden Methoden sind selbst auf Workstation‐Computern Moleküle mit mehr als 1000 Atomen auf HF‐, DFT‐ und MP2‐Niveau berechenbar.
Lebensmittelchemie 2009
Authors: Lehmann Leane , Esch Harald , Richling Elke
Published: March 2010

Hilft Kinderschokolade beim Wachsen? Schützen Soja‐Kapseln vor Osteoporose, und senkt Margarine den Cholesterolspiegel? Seit gesundheitsbezogene Angaben zu Lebensmitteln nur nach Begutachtung durch die europäische Lebensmittelsicherheitsbehörde erlaubt sind, gibt es wissenschaftlich basierte Antworten. Von den sekundären Pflanzenstoffen wurden in letzter Zeit vor allem die Polyphenole auf ihre Gehalte in Obst und Gemüse, ihre Verfügbarkeit und ihre biologische Wirksamkeit hin untersucht.
Hybrid FEM/BEM modeling of finite‐sized photonic crystals for semiconductor laser beams
Authors: Jerez‐Hanckes C. , Durán M. , Guarini M.
Published: March 2010

We propose a 2‐D finite element/boundary element hybrid method for calculating the spatial distribution and frequency response of electromagnetic waves coming from a semiconductor laser when interacting with a finite‐sized photonic crystal. We thus provide a flexible tool for the design of novel optical and microwave devices, among other applications. In opposition to current methodologies, we simultaneously take into account the laser modes, the finiteness of the crystal, and the unboundedness of the isotropic medium in which the crystal is embedded. At the laser output, instead of approximating reflected and transmitted beams by plane waves, we use the more realistic Hermite–Gauss functions. In the isotropic medium, we set an artificial boundary encircling the crystal and define exterior and interior domains. Radiating solutions for the scattered far field over the exterior are derived analytically through a series of Hankel polynomials. The interior domain is described by a finite element formulation coupled with Dirichlet‐to‐Neumann maps enforcing laser and far‐field behaviors. Results and error analyses are provided in view of future improvements. Copyright © 2010 John Wiley & Sons, Ltd.
Computational homogenization for heterogeneous thin sheets
Authors: Coenen E. W. C. , Kouznetsova V. G. , Geers M. G. D.
Published: March 2010

In this paper, a computational homogenization technique for thin‐structured sheets is proposed, based on the computational homogenization concepts for first‐ and second‐order continua. The actual three‐dimensional (3D) heterogeneous sheet is represented by a homogenized shell continuum for which the constitutive response is obtained from the nested analysis of a microstructural representative volume element (RVE), incorporating the full thickness of the sheet and an in‐plane representative cell of the macroscopic structure. At an in‐plane integration point of the macroscopic shell, the generalized strains, i.e. the membrane deformation and the curvature, are used to formulate the boundary conditions for the microscale RVE problem. At the RVE scale, all microstructural constituents are modeled as an ordinary 3D continuum, described by the standard equilibrium and the constitutive equations. Upon proper averaging of the RVE response, the macroscopic generalized stress and the moment resultants are obtained. In this way, an in‐plane homogenization is directly combined with a through thickness stress integration. From a macroscopic point of view, a (numerical) generalized stress–strain constitutive response at every macroscopic in‐plane integration point is obtained. Additionally, the simultaneously resolved microscale RVE local deformation and stress fields provide valuable information for assessing the reliability of a particular microstructural design. Copyright © 2010 John Wiley & Sons, Ltd.
A Jacobian‐free‐based IIM for incompressible flows involving moving interfaces with Dirichlet boundary conditions
Authors: Tan Zhijun , Wang Desheng , Wang Yu
Published: March 2010

In this paper, a finite difference marker‐and‐cell (MAC) scheme is presented for the steady Stokes equations with moving interfaces and Dirichlet boundary condition. The moving interfaces are represented by Lagrangian control points and their position is updated implicitly using a Jacobian‐free approach within each time step. The forces at the moving interfaces are calculated from the position of the interfaces and interpolated using cubic splines and then applied to the fluid through the related jump conditions. The proposed Jacobian‐free Newton–generalized minimum residual (GMRES) method avoids the need to form and store the matrix explicitly in the computation of the inverse of the Jacobian and betters numerical stability. The Stokes equations are discretized on a MAC grid via a second‐order finite difference scheme with the incorporation of jump contributions and the resulting saddle point system is solved by the conjugate gradient Uzawa‐type method. Numerical results demonstrate very well the accuracy and effectiveness of the proposed method. The present algorithm has been applied to solve incompressible Navier–Stokes flows with moving interfaces. Copyright © 2010 John Wiley & Sons, Ltd.
A simple dynamical scale‐coupling method for concurrent simulation of hybridized atomistic/coarse‐grained‐particle system
Authors: Kobayashi Ryo , Nakamura Takahide , Ogata Shuji
Published: March 2010

We propose a simple method for dynamical coupling of two sub‐systems with different characteristic scales described with different theoretical models, such as the fine‐scale sub‐system with the atomistic model (AM) such as the empirical inter‐atomic potential and the coarse‐scale sub‐system with the coarse‐grained particle (CGP) method, in a concurrent hybrid simulation scheme. Naive coupling of the different‐scale sub‐systems results in reflection of high wavenumber waves at the interface because of the differences in the phonon Brillouin‐zone and in the dispersion relation. To solve the problem, the present scale‐coupling method introduces (virtual) extra atoms and particles for the AM and the CGP sub‐systems, respectively, beyond the atom–particle interface, and uses the extra atoms and the particles to mutually transfer information of the waves between the two sub‐systems and to suppress the artificial reflection of the incident wave in the whole wavenumber range. As the algorithm in the present scale‐coupling method is local in time and space, it is applicable to hybrid systems with any interface shape at low computation and memory requirement. Accuracy of the present scale‐coupling method is compared with that of the existing methods for a simple model system. The hybrid AM‐CGP simulation of indentation of a graphene nano‐drum using the present scale‐coupling method is performed to demonstrate its accuracy and usefulness through its comparison with the fully atomistic results. Copyright © 2010 John Wiley & Sons, Ltd.