bluuebunny/crossref_metadata_2025 huggingface dataset:
Digital imaging in pathology – current applications and challenges
Authors: Brachtel Elena , Yagi Yukako
Published: December 2011

Conventional histopathology is rapidly shifting towards digital integration. Will microscopes (and pathologists) soon be obsolete? Or are we dealing with just another image modality that leaves the core of tissue diagnosis intact? This article provides an overview of current digital pathology applications and research with emphasis on whole slide imaging (WSI). Static or interactive digital pathology work stations already can be used for many purposes, e.g. telepathology expert consultations, frozen section diagnosis in remote areas, cytology screening, quality assurance, diagnostic validations for clinical trials, quantitation of hormone receptor or HER2 studies in breast cancer, or three‐dimensional visualization of anatomical structures, among others. Changes of workflow in histology laboratories are beginning to enable digital image acquisition and WSI in a routine setting. WSI plays an increasing role in pathology education, glass slide boxes in medical schools are being replaced by digital slide collections; digital slide seminars and virtual microscopy are used for postgraduate and continuing medical education in pathology. Research and efforts to validate WSI systems for diagnostic settings are ongoing. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of the permeability and optical clearing ability of different analytes in human normal and cancerous breast tissues by spectral domain OCT
Authors: Zhu Zhenguo , Wu Guoyong , Wei Huajiang , Yang Hongqin , He Yonghong , Xie Shusen , Zhao Qingliang , Guo Xiao
Published: December 2011

The potential of OCT applied for early breast cancer detection attracted significant efforts. The permeability coefficients and the percentages of OCT signal enhancement for normal and cancerous breast tissues have been investigated from the experiments of 20% glucose, 40% glucose, and 20% mannitol in vitro. Obtained results indicate that the permeability coefficient in breast cancer tissue is prominently larger than that in normal breast tissue, while the optical clearing effect is just the reverse to that for each agent. The results suggest that OCT has the ability to distinguish cancer tissue from different aspect. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Caveolin‐1 overexpression is associated with simultaneous abnormal expression of the E‐cadherin/α–β catenins complex and multiple erbb receptors and with lymph nodes metastasis in head and neck squamous cell carcinomas
Authors: Masuelli Laura , Budillon Alfredo , Marzocchella Laura , Mrozek Marie‐Agnes , Vitolo Domenico , Di Gennaro Elena , Losito Simona , Sale Patrizio , Longo Francesco , Ionna Franco , Lista Florigio , Muraro Raffaella , Modesti Andrea , Bei Roberto
Published: December 2011

The presence of lymph node metastases is one of the most important prognostic indicators in head and neck squamous cell carcinomas (HNSCCs). An alteration of the E‐cadherin–catenins complex and EGFR is essential for the invasiveness of cancer cells. Caveolin‐1, the major structural protein of the caveolae, represents a scaffolding molecule for several signaling proteins including EGFR. Although caveolin‐1 has been shown to play a role in inducing the invasive phenotype of cancer cells, its role appears to be cell‐type specific and for some tumors it has not been defined yet. In this study we used 57 HNSCC specimens to investigate whether the abnormal expression of caveolin‐1 was associated with the derangement of the E‐cadherin–catenins complex and with the overexpression of ErbB receptors. We demonstrate that in HNSCCs caveolin‐1 overexpression is associated with the simultaneous abnormal expression of at least one member of the E‐cadherin/α–β catenins complex and multiple ErbB receptors as well as with lymph node metastases. We also demonstrate that chronic stimulation of a human hypopharyngeal carcinoma cell line (FaDu) with EGF induced the internalization of β‐catenin and caveolin‐1 and their co‐localization with EGFR. Moreover, EGF treatment induced an increased physical interaction between EGFR/β‐catenin/caveolin‐1 and between E‐cadherin/β‐catenin/caveolin‐1. These molecular events were associated with an increased directional motility of FaDu cells in vitro. These findings may provide new insight into the biology of HNSCC progression and help to identify subgroups of primary HNSCCs with a more aggressive behavior. J. Cell. Physiol. 227: 3344–3353, 2012. © 2011 Wiley Periodicals, Inc.
Novel anti‐ErbB3 monoclonal antibodies show therapeutic efficacy in xenografted and spontaneous mouse tumors
Authors: Aurisicchio Luigi , Marra Emanuele , Luberto Laura , Carlomosti Fabrizio , De Vitis Claudia , Noto Alessia , Gunes Zeynep , Roscilli Giuseppe , Mesiti Giuseppe , Mancini Rita , Alimandi Maurizio , Ciliberto Gennaro
Published: December 2011

The role of the ErbB3 receptor in signal transduction is to augment the signaling repertoire of active heterodimeric ErbB receptor complexes through activating the PI3K/AKT pathway, which in turn promotes survival and proliferation. ErbB3 has recently been proposed to be involved in acquired resistance to tyrosine kinase inhibitors (TKIs), and is therefore a promising new drug cancer target. Since ErbB3 is a kinase defective receptor, it cannot be targeted by small molecule inhibitors, whereas monoclonal antibodies may offer a viable strategy for pharmacological intervention. In this study, we have utilized DNA electroporation (DNA‐EP) to generate a set of novel hybridomas directed against human ErbB3, which have been characterized for their biochemical and functional properties and selected for their ability to negatively regulate the ErbB3‐mediated signaling pathway. In vitro, the anti‐ErbB3 antibodies modulate the growth rate of cancer cells of different origins. In vivo they show antitumoral properties in a xenograft model of human pancreatic tumor and in the ErbB2‐driven carcinogenesis genetically engineered mouse model (GEMM) for mammary tumor, the BALB/neuT. Our data confirm that downregulating the ErbB3‐mediated signals with the use of anti‐ErbB3 monoclonal antibodies is both feasible and relevant for therapeutic purposes and provides new opportunities for novel anti‐ErbB3 combinatory strategies for cancer treatment. J. Cell. Physiol. 227: 3381–3388, 2012. © 2011 Wiley Periodicals, Inc.
Mechanisms of cytosolic targeting of matrix metalloproteinase‐2
Authors: Ali Mohammad A.M. , Chow Ava K. , Kandasamy Arulmozhi D. , Fan Xiaohu , West Lori J. , Crawford Bryan D. , Simmen Thomas , Schulz Richard
Published: December 2011

Matrix metalloproteinase‐2 (MMP‐2) is best understood for its biological actions outside the cell. However, MMP‐2 also localizes to intracellular compartments and the cytosol where it has several substrates, including troponin I (TnI). Despite a growing list of cytosolic substrates, we currently do not know the mechanism(s) that give rise to the equilibrium between intracellular and secreted MMP‐2 moieties. Therefore, we explored how cells achieve the unique distribution of this protease. Our data show that endogenous MMP‐2 targets inefficiently to the endoplasmic reticulum (ER) and shows significant amounts in the cytosol. Transfection of canonical MMP‐2 essentially reproduces this targeting pattern, suggesting it is the quality of the MMP‐2 signal sequence that predominantly determines MMP‐2 targeting. However, we also found that human cardiomyocytes express an MMP‐2 splice variant which entirely lacks the signal sequence. Like the fraction of ER‐excluded, full‐length MMP‐2, this variant MMP‐2 is restricted to the cytosol and specifically enhances TnI cleavage upon hypoxia‐reoxygenation injury in cardiomyocytes. Together, our findings describe for the first time a set of mechanisms that cells utilize to equilibrate MMP‐2 both in the extracellular milieu and intracellular, cytosolic locations. Our results also suggest approaches to specifically investigate the overlooked intracellular biology of MMP‐2. J. Cell. Physiol. 227: 3397–3404, 2012. © 2011 Wiley Periodicals, Inc.
Agonist‐activated Ca2+ influx and Ca2+‐dependent Cl− channels in Xenopus ovarian follicular cells: Functional heterogeneity within the cell monolayer
Authors: Arellano Rogelio O. , Robles‐Martínez Leticia , Serrano‐Flores Bárbara , Vázquez‐Cuevas Francisco , Garay Edith
Published: December 2011

Xenopus follicles are endowed with specific receptors for ATP, ACh, and AII, transmitters proposed as follicular modulators of gamete growth and maturation in several species. Here, we studied ion‐current responses elicited by stimulation of these receptors and their activation mechanisms using the voltage‐clamp technique. All agonists elicited Cl− currents that depended on coupling between oocyte and follicular cells and on an increase in intracellular Ca2+ concentration ([Ca2+]i), but they differed in their activation mechanisms and in the localization of the molecules involved. Both ATP and ACh generated fast Cl− (FCl) currents, while AII activated an oscillatory response; a robust Ca2+ influx linked specifically to FCl activation elicited an inward current (Iiw,Ca) which was carried mainly by Cl− ions, through channels with a sequence of permeability of SCN− > I− > Br− > Cl−. Like FCl, Iiw,Ca was not dependent on oocyte [Ca2+]i; instead both were eliminated by preventing [Ca2+]i increase in the follicular cells, and also by U73122 and 2‐APB, drugs that inhibit the phospolipase C (PLC) pathway. The results indicated that FCl and Iiw,Ca were produced by the expected, PLC‐stimulated Ca2+‐release and Ca2+‐influx, respectively, and by the opening of ICl(Ca) channels located in the follicular cells. Given their pharmacological characteristics and behavior in conditions of divalent cation deprivation, Ca2+‐influx appeared to be driven through store‐operated, calcium‐like channels. The AII response, which is also known to require PLC activation, did not activate Iiw,Ca and was strictly dependent on oocyte [Ca2+]i increase; thus, ATP and ACh receptors seem to be expressed in a population of follicular cells different from that expressing AII receptors, which were coupled to the oocyte through distinct gap‐junction channels. J. Cell. Physiol. 227: 3457–3470, 2012. © 2011 Wiley Periodicals, Inc.
Cardiac and skeletal muscle expression of mutant β‐myosin heavy chains, degree of functional impairment and phenotypic heterogeneity in hypertrophic cardiomyopathy
Authors: Di Domenico Marina , Casadonte Rita , Ricci Pietroantonio , Santini Mario , Frati Giacomo , Rizzo Antonietta , Carratelli Caterina Romano , Lamberti Monica , Parrotta Elvira , Quaresima Barbara , Faniello Concetta M. , Costanzo Francesco , Cuda Giovanni
Published: December 2011

Several mutations in distinct genes, all coding for sarcomeric proteins, have been reported in unrelated kindreds with familial hypertrophic cardiomyopathy (FHC). We have identified nine individuals from three families harboring two distinct mutations in one copy of the β‐myosin heavy chain (β‐MHC) gene. In this study, the expression of the mutant β‐myosin protein isoform, isolated from slow‐twitch fibers of skeletal muscle, was demonstrated by Northern and Western blot analysis; this myosin showed a decreased in vitro motility activity and produced a lower actin‐activated ATPase activity. Isometric tension, measured in single slow‐twitch fibers isolated from the affected individuals, also showed a significant decrease. The degree of impairment of β‐myosin function, as well as the loss in isometric tension development, were strictly dependent on the amount of the isoform transcribed from the mutated allele. Interestingly, a strong correlation was also demonstrated between mutant β‐myosin content and clinical features of FHC. On the other hand, we were unable to detect any correlation between mutant β‐myosin expression and degree of cardiac hypertrophy, thereby strengthening the hypothesis that hypertrophy, one of the hallmarks of FHC, might not necessarily be related to the clinical evolution of this disease. These findings lend support to the notion that additional factors rather than the mutated gene may play a pathogenetic role in cardiac wall thickening, whereas the prognosis appears to be strongly related to the amount of mutant protein. J. Cell. Physiol. 227: 3471–3476, 2012. © 2012 Wiley Periodicals, Inc.
Interaction of the non‐phosphorylated peptide G7‐18NATE with Grb7‐SH2 domain requires phosphate for enhanced affinity and specificity
Authors: Gunzburg Menachem J. , Ambaye Nigus D. , Del Borgo Mark P. , Pero Stephanie C. , Krag David N. , Wilce Matthew C.J. , Wilce Jacqueline A.
Published: December 2011

Src‐homology (SH2) domains are an attractive target for the inhibition of specific signalling pathways but pose the challenge of developing a truly specific inhibitor. The G7‐18NATE cyclic peptide is reported to specifically inhibit the growth factor receptor bound protein 7 (Grb7) adapter protein, implicated in the progression of several cancer types, via interactions with its SH2 domain. G7‐18NATE effectively inhibits the interaction of Grb7 with ErbB3 and focal adhesion kinase in cell lysates and, with the addition of a cell permeability sequence, inhibits the growth and migration of a number of breast cancer cell lines. It is thus a promising lead in the development of therapeutics targeted to Grb7. Here we investigate the degree to which G7‐18NATE is specific for the Grb7‐SH2 domain compared with closely related SH2 domains including those of Grb10, Grb14, and Grb2 using surface plasmon resonance. We demonstrate that G7‐18NATE binds with micromolar binding affinity to Grb7‐SH2 domain (KD = 4–6 μm) compared with 50–200 times lower affinity for Grb10, Grb14, and Grb2 but that this specificity depends critically on the presence of phosphate in millimolar concentrations. Other differences in buffer composition, including use of Tris or 2‐(N‐Morpholino)ethanesulfonic acid or varying the pH, do not impact on the interaction. This suggests that under cellular conditions, G7‐18NATE binds with highest affinity to Grb7. In addition, our findings demonstrate that the basis of specificity of G7‐18NATE binding to the Grb7‐SH2 domain is via other than intrinsic structural features of the protein, representing an unexpected mode of molecular recognition. Copyright © 2011 John Wiley & Sons, Ltd.
Nonspecific interactions in AFM force spectroscopy measurements
Authors: Celik Emrah , Moy Vincent T.
Published: December 2011

Sample‐probe contact duration (dwell time) and loading force are two important parameters for the atomic force microscopy (AFM) force spectroscopy measurements of ligand–receptor interaction. A prolonged contact time may be required to initiate ligand–receptor binding as a result of slow on‐rate kinetics or low reactant density. In general, increasing contact duration promotes nonspecific interactions between the substrate and the functionalized cantilever and, thus, masking the detection of the specific interactions. To reduce the nonspecific interactions in AFM force measurements requiring extended substrate‐probe contact, we investigated the interaction of bovine serum albumin (BSA)‐functionalized cantilever with BSA‐coated glass, polyethylene glycol (PEG)‐functionalized glass, Pluronic‐treated Petri dishes and agarose beads. The frequency of nonspecific interaction between the BSA‐functionalized cantilever and the different samples increased with loading force and dwell time. This increase in nonspecific adhesion can be attributed to the interaction mediated by forced unfolding of BSA. By reducing the loading force, the contact duration of the AFM probe with an agarose bead can be extended to a few minutes without nonspecific adhesion. Copyright © 2011 John Wiley & Sons, Ltd.
Overlapping landscapes: A persistent, but misdirected concern when collecting and analyzing ecological data
Authors: Zuckerberg Benjamin , Desrochers André , Hochachka Wesley M. , Fink Daniel , Koenig Walter D. , Dickinson Janis L.
Published: December 2011

A primary focus of wildlife ecology is studying how the arrangement, quality, and distribution of habitat influence wildlife populations at multiple spatial scales. A practical limitation of conducting wildlife–habitat investigations in the field, however, is that sampling points tend to be close to one another, resulting in spatial clustering. Consequently, when ecologists seek to quantify the effects of environmental predictors surrounding their sampling points, they encounter the issue of using landscapes that are partially or completely overlapping. A presumed problem of overlapping landscapes is that data generated from these landscapes, when used as predictors in statistical modeling, might violate the assumption of independence. However, the independence of error is the critical assumption, not the independence of predictor variables. Nonetheless, many researchers strive to avoid such overlaps through sampling design or alternative analytical procedures and specialized software programs have been created to assist with this. We present theoretical arguments and empirical evidence showing that changing the amount of overlap does not alter the degree of spatial autocorrelation. Using data derived from 2 broad‐scaled avian monitoring programs, we quantified the relationship between forest cover and bird abundance and occurrence at multiple landscapes ranging from 100 m to 24 km across. We found no clear evidence that increasing overlap of landscapes increased spatial autocorrelation in model residuals. Our results demonstrate that the concern of overlapping landscapes as a potential cause of violation of spatial independency among sampling units is misdirected and represents an oversimplification of the statistical and ecological issues surrounding spatial autocorrelation. Overlapping landscapes and spatial autocorrelation are separate issues in the modeling of wildlife populations and their habitats; non‐overlapping landscapes do not ensure spatial independency and overlapping landscapes do not necessarily lead to greater spatial autocorrelation in model errors. © 2011 The Wildlife Society.
Generalized Weyl–Wigner–Moyal–Ville Formalism and Topological Groups
Authors: Sławianowski Jan J. , Kovalchuk Vasyl , Martens Agnieszka , Gołubowska Barbara , Rożko Eliza E.
Published: December 2011

Discussed are some geometric aspects of the phase space formalism in quantum mechanics in the sense of Weyl, Wigner, Moyal, and Ville. We analyze the relationship between this formalism and geometry of the Galilei group, classical momentum mapping, theory of unitary projective representations of groups, and theory of groups algebras. Later on, we present some generalization to quantum mechanics on locally compact Abelian groups. It is based on Pontryagin duality. Indicated are certain physical aspects in quantum dynamics of crystal lattices, including the phenomenon of ‘Umklapp–Prozessen’. Copyright © 2011 John Wiley & Sons, Ltd.
The large time behavior of solutions to 3D Navier–Stokes equations with nonlinear damping
Authors: Jiang Zaihong , Zhu Mingxuan
Published: December 2011

This paper studies the Cauchy problem of the 3D Navier–Stokes equations with nonlinear damping term | u | β−1u (β ≥ 1). For β ≥ 3, we derive a decay rate of the L2‐norm of the solutions. Then, the large time behavior is given by comparing the equation with the classic 3D Navier–Stokes equations. Copyright © 2011 John Wiley & Sons, Ltd.
Blow‐up criteria of smooth solutions to the 3D Boussinesq equations
Authors: Qin Yuming , Yang Xinguang , Wang Yu‐Zhu , Liu Xin
Published: December 2011

In this paper, we investigate three‐dimensional incompressible Boussinesq equations and establish some logarithmically improved blow‐up criteria of smooth solutions to the Cauchy problem for the incompressible Boussinesq equations. Copyright © 2011 John Wiley & Sons, Ltd.
Tailored excitation using nonlinear B0‐shims
Authors: Duan Qi , van Gelderen Peter , Duyn Jeff
Published: December 2011

In high‐field MRI, RF flip angle inhomogeneity due to wavelength effects can lead to spatial variations in contrast and sensitivity. Improved flip angle homogeneity can be achieved through multidimensional excitation, but long RF pulse durations limit practical application. A recent approach to reduce RF pulse duration is based on parallel excitation through multiple RF channels. Here, an alternative approach to shorten multidimensional excitation is proposed that makes use of nonlinear spatial variations in the stationary (B0) magnetic field during a B0‐sensitive excitation pulse. As initial demonstration, the method was applied to 2D gradient echo (GE) MRI of human brain at 7 T. Using B0 shims with up to second‐order spatial dependence, it is demonstrated that root‐mean‐squared flip angle variation can be reduced from 20 to 11% with RF pulse lengths that are practical for general GE imaging applications without requiring parallel excitation. The method is expected to improve contrast and sensitivity in GE MRI of human brain at high field. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
A micromechanical modeling of ductile behavior of a porous chalk: Formulation, identification, and validation
Authors: Lin J. , Xie S.Y. , Shao J.‐F. , Kondo D.
Published: December 2011

Porosity strongly affects the overall ductile behavior of cohesive geomaterials undergoing plastic deformation. In the present paper, we proposed an original micromechanical approach that suitably couples Drucker–Prager‐type plasticity, evolving porosity under general triaxial loadings. The resulting model has the advantage to be based on a single macroscopic yield function, which also plays the role of plastic potential. It is shown that this yield function is particularly appropriate to account for the pore collapse and plastic shearing mechanisms that govern the mechanical behavior of the studied Lixhe chalk. Finally, the new model is implemented and validated by comparison to triaxial tests data, covering a wide range of confining pressures. Copyright © 2011 John Wiley & Sons, Ltd.
Amino functionalization of multiwalled carbon nanotubes by gamma ray irradiation and its epoxy composites
Authors: Zhang Chunhua , Zhu Fenglei , Wang Zhibo , Meng Linghui , Liu Yuyan
Published: December 2011

In this paper, γ‐ray radiation technique was utilized to simply functionalize multi‐walled carbon nanotube (MWCNT) with amino groups. The successful amino functionalization of MWCNTs (MWCNTs‐Am) was proven and the physicochemical properties of MWCNTs before and after radiation grafting modifications were characterized using FT‐IR, X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results indicated that the γ‐ray radiation had the visible effects on the surface properties of MWCNTs. The effects of various functionalized MWCNTs on morphological, thermal, and mechanical properties of an epoxy‐based nanocomposite system were investigated. Utilizing in situ polymerization, 1 wt% loading of MWCNT was used to prepare epoxy‐based nanocomposites. Compared to the neat epoxy system, nanocomposites prepared with MWCNT‐Am showed 13.0% increase in tensile strength, 20.0% increase in tensile modulus, and 24.1% increase in thermal decomposition temperature. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers
Processing and characterization of jute fiber reinforced hybrid biocomposites based on polylactide/polycaprolactone blends
Authors: Goriparthi Bhanu K. , Suman K.N.S. , Nalluri Mohan Rao
Published: December 2011

The main focus of this work is to develop biocomposites with improved stiffness and toughness. For this purpose, hybrid biocomposites composed of surface modified jute fiber and varying weight fractions of polylactide (PLA) and polycaprolactone (PCL) are fabricated by hot pressing of solvent impregnated prepregs. Mechanical, thermal (DSC), viscoelastic properties and biodegradation of the developed biocomposites were evaluated. Surface modification of the jute fiber resulted in improvement of tensile strength and modulus and reduction in impact toughness along with vibration damping capacity. The addition of biodegradable resin PCL to PLA matrix leads to recovery of the impact toughness and damping capacity of the biocomposites, without much sacrifice in stiffness and strength. Hybrid biocomposite with 10 wt% PCL attained an optimum balance between stiffness and toughness. In addition, PCL also accelerated the biodegradation rate of the composites. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers
Optimum consolidation of all‐polyester woven fabric‐reinforced composite laminates by film stacking
Authors: Wu C.M. , Chang C.Y. , Wang C.C. , Lin C.Y.
Published: December 2011

This study involves the examination of all‐polyester composites prepared using the two‐step consolidation of lamina and composites. The raw materials in this process are poly(ethylene terephthalate) (PET) plain woven fabric, used as reinforcement, and biodegradable polyester, used as a matrix. First, the all‐polyester laminae were produced at various consolidation temperatures (200, 210, 220, and 230°C) with a holding time of 1 min. Then, all‐polyester composites were prepared at various consolidation temperatures (200, 205, 210, 215, and 225°C) with a 3‐min holding time, using all‐polyester laminae consolidated at 220°C. This study established that proper lamina preparation is necessary for preparing a good composite, and a method is proposed that allows a wide processing window for composite preparation. The method is validated through the results of tensile, flexural, and Izod impact tests of lamina and composites. The optimum consolidation temperature observed was 220°C for all‐polyester lamina and 200–215°C for all‐polyester composites. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers
Hard‐block degradable thermoplastic urethane‐elastomers for electrospun vascular prostheses
Authors: Baudis Stefan , Ligon S. Clark , Seidler Konstanze , Weigel Guenter , Grasl Christian , Bergmeister Helga , Schima Heinrich , Liska Robert
Published: December 2011

Thermoplastic polyurethane (TPU) elastomers with biodegradable chain extenders were synthesized and tested for mechanical performance and biocompatibility. The design of the TPUs was based on structural modification of a mechanically appropriate aromatic isocyanate‐based TPU. As the aromatic isocyanate was substituted with a less toxic but also less “hard” aliphatic isocyanate, the chain extender plays an important role on the mechanical properties. Here, the terephthalate ester chain extender was found to work better than hydroxyl ethyl lactate in providing polymers with mechanical properties similar to commercial aromatic isocyanate‐based TPUs. The polymers were degraded in aqueous solutions at elevated temperatures and compared to polylactic acid (PLA) to partially simulate biodegradation. The lactate‐based TPUs degraded about twice as fast as PLA while the terephthalate‐based TPU degraded much more slowly. The latter material was processed by electrospinning to give a tubular graft approximately the size of a large rat blood vessel. Initial results from implantation of these TPUs into rats are promising and indicate that biodegradation occurs and is likely beneficial to cell proliferation. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Homopolymerization and copolymerization of a dilactone, 13,26‐dihexyl‐1,14‐dioxa‐cyclohexacosane‐2,15‐dione: Synthesis of bio‐based polyesters and copolyesters consisting of 12‐hydroxystearate sequences
Authors: Lee Chan Woo , Masutani Kazunari , Kato Tomokazu , Kimura Yoshiharu
Published: December 2011

A dilactone, 13,26‐dihexyl‐1,14‐dioxacyclohexacosane‐2,15‐dione (12‐HSAD), was synthesized by lipase‐catalyzed reaction of 12‐hydroxystearic acid (12‐HSA) in high yield. It was subjected to the ring‐opening polymerization with various catalysts to obtain poly(12‐hydroxystearate) (PHS). The polymerization system of 12‐HSAD showed an interesting polymerization behavior because of its large ring system. The polymers produced by this polymerization were directly reacted with L‐lactide to obtain a diblock copolymer of poly(L‐lactide)‐block‐poly‐(12‐hydroxystearate) (PLLA‐b‐PHS). Characterization of the resultant copolymers was also performed. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Single domain nonpolar (13$ \bar 4 $0) ZnO on (114) LaAlO3
Authors: Ho Yen‐Teng , Wang Wei‐Lin , Peng Chun‐Yen , Tian Jr‐Sheng , Shih Yi Sen , Yen Tzu‐Chen , Chang Li
Published: December 2011

An unconventional nonpolar plane (13$ \bar 4 $0) ZnO epitaxial film was grown on a 2‐inch (114) LaAlO3 (LAO) substrate by pulsed laser deposition. Reflection high energy electron diffraction (RHEED) patterns of the grown ZnO surface demonstrate single crystalline characteristics with the orientation inclined with the a‐axis. Atomic force microscopy (AFM) shows that the grown ZnO film exhibits a stripe‐like surface morphology with the longitudinal direction parallel to the c‐axis. Cross‐sectional transmission electron microscopy (TEM) with selected area electron diffraction (SAED) was used to characterize the microstructure and to determine the growth plane of ZnO grown film as (13$ \bar 4 $0). In addition, XRD pole‐figure measurements confirm the single domain growth of (13$ \bar 4 $0) ZnO on (114) LAO. Room temperature photoluminescence spectra of the ZnO film measured across the substrate show the same near band edge emission peak at 3.29 eV, indicating that the nonpolar (13$ \bar 4 $0) ZnO film has excellent uniform optical properties. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the importance of orbital localization in QC‐DMRG calculations
Authors: Mitrushchenkov Alexander O. , Fano Guido , Linguerri Roberto , Palmieri Paolo
Published: December 2011

We investigate the importance of orbital localization in the application of the Density Matrix Renormalization Group (DMRG) technique to ab initio studies of molecular electronic structure. Our previous implementation of DMRG has been generalized to allow for the use of localized nonorthogonal orbitals. Simple cycles of equidistant hydrogen atoms, which are good examples of one dimensional metal‐like lattices with fully delocalized electronic structures, have been taken as test models. In this study, the efficiency of the DMRG method and the importance of orbital localization for the generation of the DMRG building blocks are confirmed. However, it is found that the convergence of the procedure based on nonorthogonal orbitals is slower and requires more DMRG components than the standard orthogonal formulation. Symmetrically orthonormalized atomic orbitals are shown to be a good compromise solution: they satisfy the requirement of orbital localization for the generation of the DMRG blocks and improve the convergence, reducing the number of components of the DMRG expansion. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012
Theoretical investigation on identical anionic halide‐exchange SN2 reaction processes on N‐haloammonium cation NH3X+ (X = F, Cl, Br, and I)
Authors: Xiong Yan , Zhang Shuting , Ling Xuege , Zhang Xu , Wang Jinyue
Published: December 2011

CCSD(T) calculations have been used for identically nucleophilic substitution reactions on N‐haloammonium cation, X− + NH3X+ (X = F, Cl, Br, and I), with comparison of classic anionic SN2 reactions, X− + CH3X. The described SN2 reactions are characterized to a double curve potential, and separated charged reactants proceed to form transition state through a stronger complexation and a charge neutralization process. For title reactions X− + NH3X+, charge distributions, geometries, energy barriers, and their correlations have been investigated. Central barriers ΔE for X− + NH3X+ are found to be lower and lie within a relatively narrow range, decreasing in the following order: Cl (21.1 kJ/mol) > F (19.7 kJ/mol) > Br (10.9 kJ/mol) > I (9.1 kJ/mol). The overall barriers ΔE relative to the reactants are negative for all halogens: −626.0 kJ/mol (F), −494.1 kJ/mol (Cl), −484.9 kJ/mol (Br), and −458.5 kJ/mol (I). Stability energies of the ion–ion complexes ΔEcomp decrease in the order F (645.6 kJ/mol) > Cl (515.2 kJ/mol) > Br (495.8 kJ/mol) > I (467.6 kJ/mol), and are found to correlate well with halogen Mulliken electronegativities (R2 = 0.972) and proton affinity of halogen anions X− (R2 = 0.996). Based on polarizable continuum model, solvent effects have investigated, which indicates solvents, especially polar and protic solvents lower the complexation energy dramatically, due to dually solvated reactant ions, and even character of double well potential in reactions X− + CH3X has disappeared. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
The influence of hydrophobic amino acid side groups on the acidity of the aromatic imidazole ring of histidine: A theoretical study
Authors: Najafabadi Reza Izadi , Housaindokht Mohammad Reza , Sadeghi Googheri Mohammad Sadegh , Sargolzaei Mohsen , Izadyar Mohammad
Published: December 2011

In this study we have calculated the acidity constant (pKa) of imidazole ring in Histidine‐Hydrophobic amino acid dipeptides using the quantum chemistry and continuum solvation methods. Density functional theory calculations with the large basis sets are used to determine the Gibbs free energy of deprotonate in the gas and liquid phases. Based on our results ΔGS values are located between −69.38 and −18.82 kcal mol−1 which are related to His+–Gly and His forms, respectively. pKa of the dipeptides in the aqueous phase was obtained from the calculated gas‐phase and solvation free energies through a thermodynamic cycle and the solvation model chemistry of Martin Karplus et al. Solvation effects are treated using a self‐consistent reaction field formalism involving polarized continuum models. According to our calculations pKa values are between 5.50 and 8.19 that are belong to His+–ILe and His+–Ala forms, respectively. Natural bond orbital analysis of dipeptides reveals that the electron delocalization in imidazole ring is the most effective factor in determination of acidity order for these compounds. Structural analysis confirmed that the orientation of carbonyl group with respect to imidazole ring is an effective factor in imidazole ring stability. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Local angular momentum as ring strain descriptor
Authors: Azami S. M. , Kheirmand M. , Rezaei G.
Published: December 2011

A new method is demonstrated to quantify local ring strain, which is based on the expectation value of orbital angular momentum along the internuclear axis. In contrast to energy based methods which provide overall ring strain, this method is able to identify the local strain in every part of the ring. The formalism is benchmarked on several cycloalkanes in which the presence of ring strain is well understood. The ring strain plays a decisive role in carbon nanotubes (CNTs) properties; for instance, the hydrogen storage capability of CNTs is related to their diameter, which in turn has a close relation to the ring strain in their CC bonds. On this basis, the ring strain in five CNTs with different diameters is analyzed and the results reflected meaningful correlation between the CNTs diameter and ring strain. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Diffusion monte carlo study of the hydrogen molecules adsorbed on C4H3Li
Authors: Jiang Xiaoxu , Cheng Xinlu , Chen Guanyu , Zhang Hong
Published: December 2011

Diffusion Monte Carlo (DMC) simulations were used to calculate the binding energies for hydrogen molecules adsorbed on the lithium metal–organic complex C4H3Li. The calculations use all‐electron DMC techniques where every electron is explicitly included in the simulation. Also we have systematically studied it using density functional theory (DFT) methods, revealing that each C4H3Li can hold up to four H2 molecules and the adsorption distance is about 2.2 Å. The DMC binding energies are in the range of 0.055–0.143 eV and are compared with those obtained with DFT using various exchange‐correlation functionals, with values ranging from 0.029 to 0.504 eV. These results indicate that caution is required applying DFT methods to weakly bound systems such as hydrogen storage materials based on lithium‐doped metal–organic frameworks. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
The rotation‐vibration spectrum of diatomic molecules with the tietz‐hua rotating oscillator
Authors: Hamzavi M. , Rajabi A. A. , Thylwe K.‐E.
Published: December 2011

The Tietz‐Hua (TH) potential is one of the very best analytical model potentials for the vibrational energy of diatomic molecules. By using the Nikiforov‐Uvarov method, we have obtained the exact analytical s‐wave solutions of the radial Schrödinger equation for the TH potential. The energy eigenvalues and the corresponding eigenfunctions are calculated in closed forms. Some numerical results for diatomic molecules are also presented. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
The IR spectrum of supercritical water: Combined molecular dynamics/quantum mechanics strategy and force field for cluster sampling
Authors: Bordat P. , Bégué D. , Brown R. , Marbeuf A. , Cardy H. , Baraille I.
Published: December 2011

Supercritical water was analyzed recently as a gas of small clusters of waters linked to each other by intermolecular hydrogen‐bonds, but unexpected “linear” conformations of clusters are required to reproduce the infra‐red (IR) spectra of the supercritical state. Aiming at a better understanding of clusters in supercritical water, this work presents a strategy combining classical molecular dynamics to explore the potential energy landscape of water clusters with quantum mechanical calculation of their IR spectra. For this purpose, we have developed an accurate and flexible force field of water based on the TIP5P 5‐site model. Water dimers and trimers obtained with this improved force field compare well with the quantum mechanically optimized clusters. Exploration by simulated annealing of the potential energy surface of the classical force field reveals a new trimer conformation whose IR response determined from quantum calculations could play a role in the IR spectra of supercritical water. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
The investigation of nonadiabatic effects for the N + ND → N2 + D reaction
Authors: Zhang Ai‐Jie , He Guo‐Zhong
Published: December 2011

Nonadiabatic quantum dynamical calculations have been carried out on the two coupled potential energy surfaces (12A′ and 22A′) (Mota et al., J Theor Comput Chem 2009, 8, 849) for the title reaction. Initial state‐resolved reaction probabilities and cross sections for ground and excited states for collision energies of 0.005–1.0 eV are determined, respectively. Nonadiabatic transition is enhanced about four times by isotopic substitution of N + NH by N + ND reaction. It turns out that the nonadiabatic effects exert no significant contribution in the N + ND → N2 + D reaction. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Rayleigh light scattering from hydrogen‐bonded dimers of small astrophysical molecules
Authors: da Silva Arnaldo Machado , Chakraborty Sumana , Chaudhuri Puspitapallab
Published: December 2011

High level ab initio calculations of the Rayleigh scattering activities of the hydrogen‐bonded dimers of formic acid (HCOOH), nitrosyl hydride (HNO), and hydrogen cyanide (HCN) molecules have been performed. All these molecules have already been detected in interstellar space and are of great importance from the astrochemical point of view. The geometries of the homo‐ and hetero‐dimers have been optimized using Hartree–Fock and second‐order Møller‐Plesset perturbation theory. Dipole moment, mean dipole polarizability, and polarizability anisotropy have been calculated utilizing Pople‐type 6‐311++G(d,p) and Dunning's aug‐cc‐pVDZ basis sets for all the complexes. The polarizabilities are then used to calculate and analyze the Rayleigh scattering parameters. The results for the dimers, HCN···HCN, HCOOH···HCOOH, HNO···HNO, HCN···HCOOH, HCN···HNO, and HNO···HCOOH are compared with those of the isolated molecules, HCN, HCOOH, and HNO to see the effect of hydrogen bond formation on the molecular interaction with radiation. © 2011 Wiley Periodicals, Inc.
Density functional study on electronic structures and reactivity in carbazol‐oxadiazole dyads used in organic light emitting diodes
Authors: Mejia‐Urueta Rafael , Nuñez‐Zarur Francisco , Vivas‐Reyes Ricardo
Published: December 2011

In this contribution, a complete study of Triarylamine—Oxadiazole derivatives for organic light emitting diodes (OLED) applications is presented. Our purpose in this article is the establishment of correlations between the computational calculations based on density functional theory (DFT) and the experimental results with some electronic and reactivity properties. The geometries of the Triarylamine—Oxadiazole molecules are discussed in terms of the substituents groups (CF3, t‐Bu‐, CN, and CH3) and the electronics structures are described in detail in terms of the distribution of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). We also calculate the ionization potential and electron affinity with to gain insights into the nature of nucleophilic and electrophilic interactions in the studied molecules. To study the global and local reactivities use make use suitable reactivity descriptors defined on the framework of DFT. The descriptors involved in the model are global and local electrophilicity index (ω), chemical hardness (η) and softness (S), Fukui functions (f(r)), local softness (s). Correlation between the values of these quantities and the electron‐withdrawing and electron‐donor effects of triarylamine—Oxadiazole derivatives is addressed. © 2011 Wiley Periodicals, Inc.
Rapid screening of drug compounds in urine using a combination of microextraction by packed sorbent and rotating micropillar array electrospray ionization mass spectrometry
Authors: Nielsen Katrine , Lauritsen Frants R. , Nissilä Teemu , Ketola Raimo A.
Published: December 2011

RATIONALE

Screening of drugs from urine samples can be non‐selective or laborous, using either immunological, gas chromatography/mass spectrometry (GC/MS) or liquid chromatography (LC)/MS methods. Therefore, a rapid screening method for selected drugs in urine sample was developed in a proof‐of‐principle manner, utilizing simple and fast techniques for both sample treatment and sample analysis.

METHODS

Sample treament of spiked urine samples was performed with microextraction by packed sorbent (MEPS). Five different sorbent materials (C2, C8, C18, M1 (cation exchanger), and Sil (pure silica)) were tested for the MEPS. The sample analysis was performed using a circular microchip with 60 micropillar electrospray ionization (μPESI) tips combined with a mass spectrometer (either a triple‐quadrupole or ion‐trap mass spectrometer) without any chromatographic step.

RESULTS

The sample treatment/analysis setup was tested using three drug compounds at a concentration of 1 μM. We found that the C2, C8 and C18 sorbents in combination with 96% alkaline methanol as an eluent worked the best. All compounds were easily detected and identified by MS/MS in spiked urine samples. The whole qualitative analytical procedure was rapid as the sample treatment together with the MS analysis took about 5 min per sample.

CONCLUSIONS

A rapid screening method for selected drugs from urine samples was developed, providing adequate selectivity and sensitivity, as well as a short total analysis cycle time. This new method can provide a new alternative for screening purposes, as both the extraction and analysis steps could be totally automatized. Copyright © 2011 John Wiley & Sons, Ltd.
A system consisting of cation‐exchange chromatography, combined surface‐activated chemical and electrospray ionization, and ion‐trap analysis for the analysis of 8‐oxo‐7,8‐dihydro‐2'‐deoxyguanosine in urine
Authors: Cristoni Simone , Zingaro Lorenzo , Rota Cristina , Cariani Elisabetta , Trenti Tommaso
Published: December 2011

RATIONALE

8‐Hydroxy‐2'‐deoxyguanosine has served as a biomarker for oxidative damage to DNA from different types of biological samples, and various techniques have been used to analyze it. In particular, liquid chromatography coupled to mass spectrometry has been used to identify 8‐hydroxy‐2'‐deoxyguanosine in urine samples. Usually, a triple quadrupole analyzer and multiple reaction monitoring have been employed for its detection. Only a few studies have used a less expensive ion‐trap analyzer instead.

METHODS

We have developed a new liquid chromatography/mass spectrometry procedure that incorporates cation‐exchange chromatography in conjunction with surface‐activated and electrospray ionization with an ion trap analyzer for the mass spectral step.

RESULTS

The combination of two ionization sources reduced the matrix effect arising from in‐source reactions, thus increasing the sensitivity to levels comparable with those obtained by triple quadrupole analyzers.

CONCLUSIONS

This new method for 8‐hydroxy‐2'‐deoxyguanosine detection provided increased sensitivity and reduced chemical noise, using a less expensive, stable and accurate mass spectrometric technology. Copyright © 2011 John Wiley & Sons, Ltd.
Influence of oxidation state of sulfur on the dissociation of [Tz‐(CH2)n‐S(O)m‐(CH2)n‐Tz + Na+] adducts generated by electrospray ionization (Tz = tetrazole ring; n = 2, 3; m = 0, 1, 2)
Authors: Oliveira Sheila Rodrigues , Nogueira Luciano José , Augusti Rodinei , de Resende Stoianoff Maria Aparecida , Aguilar Charles Martins , Rocha Willian Ricardo , Donnici Claudio Luis
Published: December 2011

Sodium adducts of six organosulfur‐α,ω‐ditetrazole compounds (Tz‐(CH2)n‐S(O)m‐(CH2)n‐Tz; where Tz = tetrazole ring; n = 2, 3; m = 0, 1, 2) were generated via electrospray ionization (ESI) and their fragmentation pattern assessed via collision‐induced dissociation (CID). Two main dissociation channels were observed: (a) losses of N2 and HN3 from the tetrazole rings; (b) cleavage of the C–S bond. The sulfoxides pass predominantly through the second fragmentation pathway, but for the sulfides and sulfones the tetrazole ring fragmentation occurs. Theoretical calculations at the B3LYP/6‐31 + G(d,p) level indicate that for all the adducts (sulfide, sulfoxide, and sulfone) the dissociation pathway that leads to product ions arising from loss of N2 was the most exothermic. Based on these results and assumptions, it was postulated that the dissociation of the sulfoxide adducts occurs under kinetic control (N2‐loss pathway via a much more energetic transition state). For the sulfide and sulfone adducts, on the other hand, the dissociation process takes place via a thermodynamically controlled process. Copyright © 2011 John Wiley & Sons, Ltd.
Quantized stabilization for stochastic discrete‐time systems with multiplicative noises
Authors: Wei Li , Zhang Huanshui , Fu Minyue
Published: December 2011

This paper considers the problem of quadratic mean‐square stabilization of a class of stochastic linear systems using quantized state feedback. Different from the previous works where the system is restricted to be deterministic, we focus on stochastic systems with multiplicative noises in both the system matrix and the control input. A static quantizer is used in the feedback channel. It is shown that the coarsest quantization density that permits stabilization of a stochastic system with multiplicative noises in the sense of quadratic mean‐square stability is achieved with the use of a logarithmic quantizer, and the coarsest quantization density is determined by an algebraic Riccati equation, which is also the solution to a special stochastic linear control problem. Our work is then extended to exponential quadratic mean‐square stabilization of the same class of stochastic systems. Copyright © 2011 John Wiley & Sons, Ltd.