bluuebunny/crossref_metadata_2025 huggingface dataset:
Sinusoidal C4d deposits in liver allografts indicate an antibody-mediated response: Diagnostic considerations in the evaluation of liver allografts
Authors: Kozlowski Tomasz , Andreoni Kenneth , Schmitz John , Hideo Hayashi Paul , Nickeleit Volker
Published: February 2012

There is a paucity of data concerning the correlation of complement component 4d (C4d) staining in liver allografts and antibody-mediated rejection. Data about the location and character of C4d deposits in native and allograft liver tissues are inconsistent. We performed C4d immunofluorescence (IF) on 141 fresh-frozen liver allograft biopsy samples and native livers, documented the pattern of C4d IF staining, and correlated the findings with the presence of donor-specific alloantibodies (DSAs). A linear/granular sinusoidal pattern of C4d IF was noted in 18 of 28 biopsy samples obtained after transplantation from patients with positive crossmatch and detectable donor-specific alloantibody (pos-XM/DSA) findings. None of the 59 tested biopsy samples from patients with negative crossmatch and detectable donor-specific alloantibody (neg-XM/DSA) findings were C4d-positive (P < 0.001). No significant association was found between pos-XM/DSA and C4d IF staining in other nonsinusoidal liver compartments. To compare the results of sinusoidal C4d staining with IF and 2 immunohistochemistry (IHC) techniques, C4d IHC was performed on 19 liver allograft biopsy samples in which a sinusoidal pattern of C4d IF had been noted. Sinusoidal C4d IHC findings were negative for 17 of the 19 biopsy samples; 2 showed weak and focal staining, and both patients had pos-XM/DSA findings. Portal vein endothelium staining was present in only 1 IF-stained biopsy sample (pos-XM/DSA) but in 11 IHC-stained biopsy samples (2 of the 11 samples had neg-XM/DSA findings). We conclude that sinusoidal C4d deposits detected by IF in frozen tissue samples from liver allograft recipients correlate with the presence of DSAs and an antibody-mediated alloresponse. These observations are similar to findings reported for other solid organ transplants and can provide relevant information for patient management. Further validation of IHC techniques for C4d detection in liver allograft tissue is required.
Maximal regularity with temporal weights for parabolic problems with inhomogeneous boundary conditions
Authors: Meyries Martin , Schnaubelt Roland
Published: February 2012

We develop a maximal regularity approach in temporally weighted Lp‐spaces for vector‐valued parabolic initial‐boundary value problems with inhomogeneous boundary conditions, both of static and of relaxation type. Normal ellipticity and conditions of Lopatinskii‐Shapiro type are the basic structural assumptions. The weighted framework allows to reduce the initial regularity and to avoid compatibility conditions at the boundary, and it provides an inherent smoothing effect of the solutions. Our main tools are interpolation and trace theory for anisotropic Slobodetskii spaces with temporal weights, operator‐valued functional calculus, as well as localization and perturbation arguments.
Transformation of Regioregular Organotitanium Polymers into Group 16 Heterole‐Containing π‐Conjugated Materials
Authors: Nishiyama Hiroki , Kino Tomoko , Tomita Ikuyoshi
Published: February 2012

Regioregular organometallic polymers with titanacyclopentadiene units, obtained from terminal diynes and a low‐valent titanium complex, were subjected to reactions with disulfur dichloride and selenium (I) chloride to give π‐conjugated polymers with thiophene and selenophene units in the main chain in 63% and 86% yields. Their number‐average molecular weights were estimated as 4300 and 5700, respectively. Both polymers were found to be fully π‐conjugated and their HOMO energy levels were remarkably high (–5.3 eV and –5.0 eV for thiophene‐ and selenophene‐containing polymers, respectively) as supported by their UV‐vis absorption spectra and CV analyses.
Controlled Radical Polymerization Mediated by Amine–Bis(phenolate) Iron(III) Complexes
Authors: Allan Laura E. N. , MacDonald Jarret P. , Reckling Amy M. , Kozak Christopher M. , Shaver Michael P.
Published: February 2012

Tetradentate amine–bis(phenolate) iron(III) halide complexes containing chloro substituents on the aromatic ring are extremely efficient catalysts for controlled radical polymerization. Molecular weights are in good agreement with theoretical values and polydispersity indexes (PDIs) are as low as 1.11 for styrene and methyl methacrylate polymerizations. Complexes containing alkyl substituents on the aromatic ring are less efficient. Kinetic data reveal activity for styrene polymerization among the fastest reported to date and initial studies implicate a multimechanism system. Despite the highly colored polymerization media, simple work‐up procedures yield pure white polymers.
A new sequence for single‐shot diffusion‐weighted NMR spectroscopy by the trace of the diffusion tensor
Authors: Valette Julien , Giraudeau Céline , Marchadour Charlotte , Djemai Boucif , Geffroy Françoise , Ghaly Mohamed Ahmed , Le Bihan Denis , Hantraye Philippe , Lebon Vincent , Lethimonnier Franck
Published: February 2012

Diffusion‐weighted spectroscopy is a unique tool for exploring the intracellular microenvironment in vivo. In living systems, diffusion may be anisotropic, when biological membranes exhibit particular orientation patterns. In this work, a volume selective diffusion‐weighted sequence is proposed, allowing single‐shot measurement of the trace of the diffusion tensor, which does not depend on tissue anisotropy. With this sequence, the minimal echo time is only three times the diffusion time. In addition, cross‐terms between diffusion gradients and other gradients are cancelled out. An adiabatic version, similar to localization by adiabatic selective refocusing sequence, is then derived, providing partial immunity against cross‐terms. Proof of concept is performed ex vivo on chicken skeletal muscle by varying tissue orientation and intra‐voxel shim. In vivo performance of the sequence is finally illustrated in a U87 glioblastoma mouse model, allowing the measurement of the trace apparent diffusion coefficient for six metabolites, including J‐modulated metabolites. Although measurement performed along three separate orthogonal directions would bring similar accuracy on trace apparent diffusion coefficient under ideal conditions, the method described here should be useful for probing intimate properties of the cells with minimal experimental bias. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.
Woher die Schärfe kommt
Authors: Müller‐Seitz Erika , Petz Michael
Published: February 2012

Das besondere Merkmal von Chili‐ und Paprika‐Früchten ist ihr scharfes Aroma. Welche Faktoren sind dafür verantwortlich?
Die fabelhafte Welt der Allene
Authors: Krause Norbert
Published: February 2012

Das kumulierte Doppelbindungssystem der Allene fasziniert Chemiker seit langem. Die hohe Reaktivität und die axiale Chiralität machen Allene zu Zielmolekülen und wertvollen Bausteinen für die Synthese komplexer Folgeprodukte.
Chemische Evolution auf der Vulkaninsel
Authors: Neubauer Uta
Published: February 2012

Wie im Chaos der Urerde komplexe Biomoleküle und schließlich die ersten Organismen entstanden, bleibt rätselhaft. Wissenschaftler der Universität Hohenheim favorisieren Vulkaninseln als Ursprungsort von Leben. Mit Laborexperimenten belegen sie ihre Theorie.
Restaurierung historischer Uhren — ein Stück praktischer Chemie
Authors: Simon Arndt
Published: February 2012

Uhren sind ein faszinierendes Stück menschlicher Kultur‐ und Technikgeschichte. Bei der Restaurierung historischer Uhren hilft chemischer Sachverstand.
Strukturformeln als Text speichern
Authors: Rößler Ulrich
Published: February 2012

Der International Chemical Identifier Inchi beschreibt chemische Verbindungen ausgehend von Strukturinformationen und macht sie so maschinenlesbar. Wie entstanden die Inchi‐Zeichenketten und wie sind sie aufgebaut?
Technische Revolution und wirtschaftliche Reaktion
Authors: von Delft Stephan , Leker Jens
Published: February 2012

Beim Zukunftstrend Elektromobilität erfährt die Batterietechnik viel Aufmerksamkeit. Übersehen wird dabei, dass hervorragende Batterietechnik zwar eine notwendige, aber keine hinreichende Bedingung für einen Erfolg im elektromobilen Markt der Zukunft ist.
Bor: Isotopenverhältnisse und die Herkunft einer Probe
Authors: Rosner Martin , Vogl Jochen
Published: February 2012

Die Industrie nutzt die Borisotopenanalytik in nukleartechnischen Anwendungen. Umwelt‐ und Geo wissenschaften identifizieren anhand der Borisotopenverhältnisse Kontaminationsquellen und charakterisieren Mischungs‐ und Fraktionierungsprozesse. In der Lebensmittelanalytik dient der Parameter dazu, Herkunft und Anbauweise von Obst und Gemüse herauszufinden. Seit Kurzem gibt es dafür ein validiertes Verfahren und erste Referenzdaten.
Wirtschaftschemiker, berufsbegleitend
Authors: Leker Jens , Kehrel Uwe
Published: February 2012

Ein neues Fortbildungsprogramm der Gesellschaft Deutscher Chemiker vermittelt betriebswirtschaftliche Kenntnisse für die chemische Industrie. Es ist speziell für solche Naturwissenschaftler konzipiert, die bereits Berufserfahrung haben und sich für ihre weitere Karriere qualifizieren wollen.
Blood oxygen level dependent angiography (BOLDangio) and its potential applications in cancer research
Authors: Cai Kejia , Shore Adam , Singh Anup , Haris Mohammad , Hiraki Teruyuki , Waghray Prianka , Reddy Damodar , Greenberg Joel H. , Reddy Ravinder
Published: February 2012

Clinically, development of anti‐angiogenic drugs for cancer therapy is pivotal. Longitudinal monitoring of tumour angiogenesis can help clinicians determine the effectiveness of anti‐angiogenic therapy. Blood oxygen level dependent (BOLD) effect has been widely used for functional imaging and tumour oxygenation assessment. In this study, the BOLD effect is investigated under different levels of oxygen inhalation for the development of a novel angiographic MRI technique, blood oxygen level dependent angiography (BOLDangio). Under short‐term (<10 min) generalized hypoxia induced by inhalation of 8% oxygen, we measure BOLD contrast as high as 25% from vessels at 9.4T using a simple gradient echo (GRE) pulse sequence. This produces high‐resolution 2D and 3D maps of normal and tumour brain vasculature in less than 10 minutes. Additionally, this technique reliably detects metastatic tumours and tumour‐induced intracranial hemorrhage. BOLDangio provides a sensitive research tool for MRI of vasculature under normal and pathological conditions. Thus, it may be applied as a simple monitoring technique for measuring the effectiveness of anti‐angiogenic drugs in a preclinical environment. Copyright © 2012 John Wiley & Sons, Ltd.
Experimental analysis of a Fast Adaptive Composite‐based grid expansion scheme for open boundary problems
Authors: Ritter Daniel , Rüde Ulrich
Published: February 2012

Poisson's equation on unbounded domains was solved with a hierarchical grid coarsening approach on the basis of Stephen F. McCormick's Fast Adaptive Composite grid method. We were especially interested in the efficient interface treatment that is enabled by regular stencils. The error behavior of a second‐order scheme was empirically analyzed for an exemplary setup from molecular dynamics. Comparisons with previous methods were also performed and showed that our approach is competitive. Copyright © 2012 John Wiley & Sons, Ltd.
Krylov‐accelerated algebraic multigrid for semi‐definite and nonsymmetric systems in computational fluid dynamics
Authors: Emans Maximilian
Published: February 2012

This article reports on experiences with aggregation algebraic multigrid relying on Krylov acceleration on each level of the grid hierarchy as preconditioners for linear systems in general purpose fluid flow simulation software. In benchmarks that reflect the requirements of industrial simulations, it is demonstrated that for semi‐definite problems, the performance of recently published algorithms of this type is very attractive but that proposed variants of these algorithms occasionally fail for nonsymmetric problems. A modification leading to reliable solvers is suggested. Copyright © 2012 John Wiley & Sons, Ltd.
Block preconditioners for finite element discretization of incompressible flow with thermal convection
Authors: Howle Victoria E. , Kirby Robert C.
Published: February 2012

We derive block preconditioners for a finite element discretization of incompressible flow coupled to heat transport by the Boussinesq approximation. Our techniques rely on effectively approximating the Schur complement obtained by eliminating the fluid variables to obtain an equation for temperature alone. Additionally, the method utilizes existing block‐structured preconditioners and multilevel methods for the Navier–Stokes equations and scalar convection–diffusion. We find that the preconditioner remains robust and scalable even when the subsolves are applied quite inexactly. Copyright © 2012 John Wiley & Sons, Ltd.
Algebraic multigrid for discontinuous Galerkin discretizations of heterogeneous elliptic problems
Authors: Bastian Peter , Blatt Markus , Scheichl Robert
Published: February 2012

We present a new algebraic multigrid (AMG) algorithm for the solution of linear systems arising from discontinuous Galerkin (DG) discretizations of heterogeneous elliptic problems. The algorithm is based on the idea of subspace corrections, and the first coarse level space is the subspace spanned by continuous linear basis functions. The linear system associated with this space is constructed algebraically using a Galerkin approach with the natural embedding as the prolongation operator. This embedding operator needs to be provided, which means that the approach is not fully algebraic. For the construction of the linear systems on the subsequent coarser levels, non‐smoothed aggregation AMG techniques are used. In a series of numerical experiments, we establish for the first time the efficiency and robustness of an AMG method for various symmetric and non‐symmetric interior penalty DG methods (including the higher‐order cases) on problems with complicated, high contrast jumps in the coefficients. The solver is robust with respect to an increase in the polynomial degree of the DG approximation space (at least up to degree 6), computationally efficient, and affected only mildly by the coefficient jumps and by the mesh size h (i.e., number of iterations = O(log h−1)). Copyright © 2012 John Wiley & Sons, Ltd.
Population‐based survival for childhood cancer patients diagnosed during 2002–2005 in Shanghai, China
Authors: Bao Ping‐ping , Zheng Ying , Wu Chun‐xiao , Peng Peng , Gong Yang‐ming , Huang Zhe‐zhou , Fan Wu
Published: February 2012

Background

There have been no population‐based studies on cancer survival among children aged 0–14 years in China. In this study, we aimed to characterize the cancer survival among children in Shanghai.

Procedure

Childhood cancer cases registered by the Shanghai Cancer Registry between 2002 and 2005 and enrolled in the Shanghai Childhood Survival Study were included in this study. We used Kaplan–Meier product‐limit method for survival analysis and Cox proportional hazards models for investigating the effects of various prognostic factors.

Results

The median follow‐up time was 5.4 years (range 0–8.9 years). The 5‐year observed survival for all childhood cancers combined was 55.7% (95% CI: 51.7–59.6%). For leukemia, lymphoma, and central nervous system tumors, the three most common types of childhood cancer, 5‐year survival rates were 52.2%, 58.8%, and 41.2%, respectively. Higher 5‐year survival rates were observed for epithelial cancer (88.9%), malignant renal tumors (86.7%), germ cell and other gonadal tumors (78.4%), and retinoblastoma (75.0%). Cancers with poor prognosis included sympathetic nervous system tumors (57.9%), soft tissue sarcoma (54.1%), bone tumors (52.6%), and liver cancer (33.3%). There were no significant differences between survival rates by gender and age groups. Compared with those reported in the USA and Europe, the survival rates for all cancers combined and the three most common types in Shanghai were lower.

Conclusions

The survival rate for children aged 0–14 diagnosed with cancer in Shanghai during 2002–2005 was at the medium level. There was a substantial survival difference from childhood cancers between Shanghai and specific developed countries. Pediatr Blood Cancer 2012;59:657–661. © 2012 Wiley Periodicals, Inc.
Feasibility, reliability, and validity of the pediatric quality of life inventory™ generic core scales, cancer module, and multidimensional fatigue scale in long‐term adult survivors of pediatric cancer
Authors: Robert Rhonda S. , Paxton Raheem J. , Palla Shana L. , Yang Grace , Askins Martha A. , Joy Shaini E. , Ater Joann L.
Published: February 2012

Background

Most health‐related quality of life assessments are designed for either children or adults and have not been evaluated for adolescent and young adult survivors of pediatric cancer. The objective of this study was to examine the feasibility, reliability, and validity of the Pediatric Quality of Life Inventory (PedsQLTM) Generic Core Scales, Cancer Module, and Multidimensional Fatigue Scale in adult survivors of pediatric cancer.

Methods

Adult survivors (n = 64; Mean age 35 year old; >2 years after treatment) completed the PedsQL™ Generic Core Scales, Cancer Module, and Multidimensional Fatigue Scale. Feasibility was examined with floor and ceiling effects; and internal consistency was determined by Cronbach's coefficient alpha calculations. Inter‐factor correlations were also assessed.

Results

Significant ceiling effects were observed for the scales of social function, nausea, procedural anxiety, treatment anxiety, and communication. Internal consistency for all subscales was within the recommended ranges (α ≥ 0.70). Moderate to strong correlations between most Cancer Module and Generic Core Scales (r = 0.25 to r = 0.76) and between the Multidimensional Fatigue Scale and Generic Core Scales (r = 0.37 to r = 0.73).

Conclusions

The PedsQL™ Generic Core Scales, Cancer Module, and Multidimensional Fatigue Scale appear to be feasible for an older population of pediatric cancer survivors; however, some of the Cancer Module Scales (nausea, procedural/treatment anxiety, and communication) were deemed not relevant for long‐term survivors. More information is needed to determine whether the issues addressed by these modules are meaningful to long‐term adult survivors of pediatric cancers. Pediatr Blood Cancer 2012;59:703–707. © 2012 Wiley Periodicals, Inc.
Gemcitabine and docetaxel (GEMDOX) for the treatment of relapsed and refractory pediatric sarcomas
Authors: Rapkin Louis , Qayed Muna , Brill Pam , Martin Melissa , Clark Dana , George Bradley A. , Olson Thomas A. , Wasilewski‐Masker Karen , Alazraki Adina , Katzenstein Howard M.
Published: February 2012

Background

Patients with relapsed pediatric sarcomas have a poor outcome and are in need of novel effective therapies.

Methods

We retrospectively reviewed the records of patients at Children's Healthcare of Atlanta who were treated with gemcitabine (675 mg/m2) intravenously (IV) on Day 1 and Day 8, and docetaxel (75 mg/m2) IV on Day 8, repeated every 3 weeks.

Results

Nineteen patients with a median age of 11 years were treated from 2006–2010 and received 123 total courses. Two patients (11%), both with rhabdomyosarcoma, demonstrated objectives responses [one complete response (CR) and one partial response (PR)]. Seven other patients (39%) had stable disease (SD). The 1‐year progression‐free survival (PFS) of the entire cohort was 24% ± 10% with a median time to progression of 2 months (range: 0.5–14 months). The 1‐year overall survival (OS) was 43% ± 11%. Grade 3 or 4 toxicities occurred in 14 patients (74%) and 52 courses (42%), and were most commonly hematologic (neutropenia = 37, anemia = 17, and thrombocytopenia = 23 courses).

Conclusions

The dismal outcomes for patients with relapsed and refractory sarcomas and the lack of effective sarcoma salvage regimens highlight the need for new approaches. This report of the therapeutic activity of gemcitabine and docetaxel (GEMDOX) in rhabdomyosarcoma and other pediatric reports describing activity in osteosarcoma and Ewing sarcoma suggest that this combination should be considered for formal evaluation in a pediatric specific clinical trial. At a minimum, it appears to offer a reasonable, tolerable, palliative option. Pediatr Blood Cancer 2012; 59: 854–858. © 2012 Wiley Periodicals, Inc.
Analysis and design of phase‐interleaving series‐connected module‐integrated converter for DC‐link ripple reduction of multi‐stage photovoltaic power systems
Authors: Jung An‐Yeol , Park Joung‐Hu , Jeon Hee‐Jong
Published: February 2012

Recently, installation of photovoltaic power systems such as building‐integrated photovoltaic in urban area has been spotlighted in renewable energy engineering field, even at the expense of the performance degradation from partial shading. The efficiency degradation of maximum power point tracking (MPPT) performance can be compensated by a kind of power‐conditioning system architecture such as module‐integrated converters (MIC), which can handle the optimal‐operation tracking for its own photovoltaic (PV) module. In case of a MIC with series‐connected outputs, it is easy to obtain a high DC‐link voltage for multiple stage PV power conditioning applications. However, switching ripple of the DC‐link voltage also increases as number of the modules increases.

In this paper, as a solution for the ripple reduction, interleaved pulse width modulation‐phase synchronizing method is applied to the PV MIC modules. The switching‐ripple analysis of the MPPT power modules were performed and compared between the cases such as phase control or not. For the implementation of the phase control among the modules, Zigbee (XBee Pro, Digi International, Minnetonka, MN, USA) wireless communications transceiver and DSP (TMS320F28335, Texas Instruments, Dallas, TX, USA) series communications interface are utilized. Hardware prototype of the double‐module boost‐type 80‐W MICs has been built to validate the DC‐link voltage ripple reduction. Copyright © 2012 John Wiley & Sons, Ltd.
System memory effects in the sizing of stand‐alone PV systems
Authors: Fragaki Aikaterini , Markvart Tom
Published: February 2012

Models based on daily energy balance (or long‐term models) have been widely used as a tool in the stand‐alone photovoltaic (PV) system sizing, mainly with the purpose of obtaining analytical expressions of the relation between the generator size and the storage capacity of the battery. The system can then be designed to meet the reliability requirements of the specific case. However, such models represent the complex operation of a stand‐alone system in an oversimplified way. There is little research so far on the reliability and improvement of such models. Validation and possible modification of a long‐term system model requires comparison of the simulated state of charge (SOC) of the battery with that obtained from an experimental system. In this work, experimental data from a 6‐month operation of a basic stand‐alone PV system have been analysed and compared with modelling results. One obvious improvement that could be applied to the long‐term system model is to account for a charging efficiency of the battery, and this possibility is examined in the present work. However, comparison with the modelling results shows that the data cannot be fitted by simply taking into account battery inefficiency. A method to account for system memory effects in the increase of the battery SOC, imposed by the operation of the regulator, is necessary to accurately model the macroscopic diurnal charging/discharging process. Copyright © 2012 John Wiley & Sons, Ltd.
Control of thermal properties and hydrolytic degradation in poly(lactic acid) polymer stars through control of isospecificity of polymer arms
Authors: Cameron Donald J. A. , Shaver Michael P.
Published: February 2012

The synthesis of a family of polymer stars with arms of varied tacticities is discussed. The effect of polymer tacticity on the physical properties of these polymer stars is dramatic. Dipentaerythritol cores support six poly(lactic acid) arms. Lewis acidic tin and/or aluminum catalysts control the polymerization to afford polymer stars of variable tacticity. Analysis of these polymers by 1H NMR spectroscopy, thermogravimetric analysis, powder X‐ray diffraction, and differential scanning calorimetry reveals the effects of tacticity control on the physical properties of the polymer stars. Hydrolytic decomposition studies suggest that the degradation profile of a polymer star may also be tuned by stereochemical control. Differences between isotactic samples derived from rac‐lactide and L‐lactide are heightened by longer arms of 50 and 100 monomer units. Control of polymer isospecificity shows that a ∼70% isotacticity bias is necessary to induce crystallinity and alter the thermal and degradation properties of the material. Above 70% isotacticity, the degradation properties and thermal transitions can be further tuned across a relatively wide range. This technique allows for significant tunability to the physical properties of aliphatic polyester polymer stars. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Interactions of oligomers of organic polyethers with histidine amino acid
Authors: Zobnina Valentina G. , Kosevich Marina V. , Chagovets Vitaliy V. , Boryak Oleg A. , Vékey Károly , Gömöry Ágnes , Kulyk Anna N.
Published: February 2012

RATIONALE

Knowledge on noncovalent intermolecular interactions of organic polyethers with amino acids is essential to gain a better understanding on how polymers assemble in organic nanoparticles which are promising for drug delivery and cryoprotection. The main objective of the present study was to determine how polyethers assemble around ionizable amino acids such as histidine.

METHODS

Electrospray mass spectrometry was applied to probe the interactions in model systems consisting of polyethylene glycol PEG‐400 or oxyethylated glycerol OEG‐5 and amino acid histidine hydrochloride. Molecular dynamics simulation was utilized to visualize the structure of complexes of polyether oligomers with histidine in different charge states.

RESULTS

Stable gas‐phase clusters composed of polyether oligomers (PEGn, OEGn) with protonated histidine ‐ PEGn•His•H+, OEGn•His•H+, OEGn•OEGm•His•H+ and chlorine counterion – PEGn•Cl‐, OEGn•Cl‐, were observed under electrospray conditions. Molecular dynamics simulation of representative polyether‐histidine complexes revealed the stabilization of oligomers by multiple hydrogen and coordination bonds whereby charged groups are wrapped by the polymeric chains.

CONCLUSIONS

The self‐organization of polyether chains around the protonated imidazole group of histidine was revealed. This finding should be considered when modelling a pegylated protein structure and polyether‐based organic nanoparticles. Copyright © 2012 John Wiley & Sons, Ltd.
Analysis of cipadesin limonoids from Cipadessa cinerascens using electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry and quantum chemical calculations
Authors: Wu Zhi‐Jun , Sun Dong‐Ming , Chen Jian‐Zhong , Chen Xiao‐Zhen , Fang Dong‐Mei , Li Na , Cheng Ping , Zhang Guo‐Lin
Published: February 2012

RATIONALE

Limonoids, a class of tetranortriterpenoids, exhibit various biological effects, such as insect antifeedant and growth regulating activities, antimicrobial activity, potent cell adhesion inhibitory effects, antimalarial activity, anticancer activities, and antioxidant activity. The potential application brings the need for reliable, fast and low‐cost analysis of this class of compounds.

METHODS

Six cipadesin limonoids (1–6), including a pairs of isomers, from leaves and barks of Cipadessa cinerascens were investigated by electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry (ESI‐QTOF‐MS/MS) in positive‐ion mode. Characteristic processes were further studied by theoretical calculations.

RESULTS

1,3‐Hydrogen rearrangement might play a significant role in the cleavage of ‐O‐ bridge bond in ring B and further produces some characteristic ions. For [M + Na]+ precursor ions, the product ion at m/z 133 might indicate the structure of ring A and the losses of CO2 and AcOH occur readily. Interestingly, the radical product ion at m/z 460 from [M + Na]+ ions seems to be the characteristic ion for compound 1. A deuterium‐labeling experiment supported the processes forming the radical ion. For [M + NH4]+ ions, high‐abundance product ions resulting from sequential loss of AcOH can be observed. In addition, a pairs of isomers was unambiguously differentiated based on MS or MS/MS spectra.

CONCLUSIONS

In summary, sufficient information obtained from fragmentation experiments of [M + Na]+, [M + NH4]+ or [M + H]+ precursor ions is especially valuable for rapid identification of these limonoids or their metabolites in complex mixtures. The high‐abundance radical product ion is of scientific interest. Copyright © 2012 John Wiley & Sons, Ltd.
Perfluorooctanoic acid and ammonium perfluorooctanoate: volatile surfactants for proteome analysis?
Authors: Vieira Douglas B. , Crowell Andrew M. J. , Doucette Alan A.
Published: February 2012

RATIONALE

Fluorinated surfactants are being explored as mass spectrometry (MS)‐friendly alternatives to sodium dodecyl sulfate (SDS) for proteome analysis. Previous work demonstrates perfluorooctanoic acid (PFOA) to be compatible with electrospray ionization (ESI)‐MS. The high volatility of PFOA provides an intrinsic approach to potentially eliminate the surfactant during ESI, or alternatively through solvent evaporation prior to MS. The ammonium salt of PFOA, ammonium perfluorooctanoate (APFO), is likely favored for proteome experiments; the MS and liquid chromatography (LC)/MS tolerance of APFO has not been established for proteome applications.

METHODS

Standard proteins and peptides, as well as a yeast proteome mixture, were individually spiked with surfactants (APFO, PFOA, SDS), and subjected to direct infusion ESI‐MS, LC/MS/MS and LC/UV. The level of fluorinated surfactant remaining after solvent evaporation under varying conditions (time, pH, salt and protein content) was quantified and compared to the threshold tolerance level of the surfactant in an MS experiment (determined herein).

RESULTS

Whereas PFOA is found ineffective at assisting protein solubilization, APFO is as effective as SDS for resolubilization of acetone‐precipitated yeast proteins (~100% recovery). Unfortunately, the LC and MS threshold tolerance of APFO is only minimally greater than SDS (~2‐fold higher concentration to cause 50% suppression). Nonetheless, the benefits of APFO in a proteome experiment are realized following a one‐step evaporation protocol for removal of the surfactant in acidified solvent.

CONCLUSIONS

APFO is considered a favoured alternative to SDS for proteome solubilization. Strictly speaking, APFO is not an 'MS‐friendly' surfactant for proteome characterization; the detergent not only suppresses ESI signals at high concentration, but also perturbs reversed phase separation. However, the simplicity of APFO removal ahead of LC/MS justifies its use over the conventional SDS. Copyright © 2012 John Wiley & Sons, Ltd.
Using complementary mass spectrometric approaches for the determination of methylprednisolone metabolites in human urine
Authors: Pozo Oscar J. , Marcos Josep , Matabosch Xavier , Ventura Rosa , Segura Jordi
Published: February 2012

RATIONALE

The metabolism of methylprednisolone is revisited in order to find new metabolites that could be important for distinguishing between different routes of administration. Recently developed liquid chromatography/tandem mass spectrometry (LC/MS/MS) strategies for the detection of corticosteroid metabolites have been applied to the study of methylprednisolone metabolism.

METHODS

The structures of these metabolites were studied using two complementary mass spectrometric techniques: LC/MS/MS in product ion scan mode with electrospray ionization and gas chromatography/mass spectrometry (GC/MS) in full scan mode with electron ionization. Metabolites were also isolated by semipreparative liquid chromatography fractionation. Each fraction was divided into two aliquots; one was studied by LC/MS/MS and the other by GC/MS after methoxyamine‐trimethylsilyl derivatization.

RESULTS

The combination of all the structural information allowed us to propose a comprehensive picture of methylprednisolone metabolism in humans. Overall, 15 metabolites including five previously unreported compounds have been detected. Specifically, 16β,17α,21‐trihydroxy‐6α‐methylpregna‐1,4‐diene‐3,11,20‐trione, 17α,20β,21‐trihydroxy‐6α‐methylpregna‐1,4‐diene‐3, 11‐dione, 11β,17α,21‐trihydroxy‐6α‐hydroxymethylpregna‐1,4‐diene‐3,20‐dione, 11β,17α,20ξ,21‐tetrahydroxy‐6α‐hydroxymethylpregna‐1,4‐diene‐3‐one, and 17α,21‐dihydroxy‐6α‐hydroxymethylpregna‐1,4‐diene‐3,11,20‐trione are proposed as feasible structures for the novel metabolites. In addition to the expected biotransformations: reduction of the C20 carbonyl, oxidation of the C11 hydroxy group, and further 6β‐hydroxylation, we propose that hydroxylation of the 6α‐methyl group can also take place.

CONCLUSIONS

New metabolites have been identified in urine samples collected after oral administration of 40 mg of methylprednisolone. All identified metabolites were found in all samples collected up to 36 h after oral administration. However, after topical administration of 5 g of methylprednisolone aceponate, neither the parent compound nor any of the metabolites were detected. Copyright © 2012 John Wiley & Sons, Ltd.
Improved accuracy in high‐temperature conversion elemental analyzer δ18O measurements of nitrogen‐rich organics
Authors: Hunsinger Glendon B. , Stern Libby A.
Published: February 2012

RATIONALE

The use of high‐temperature conversion (HTC) reduction systems interfaced with isotope ratio mass spectrometers for δ18O measurements of nitrogen‐containing organic materials is complicated by isobaric interference from 14N16O+. This ion is produced in the ion source when N2 reacts with trace oxygen shifting the m/z 30 baseline prior to elution of CO.

METHODS

We compared adaptations to a typical HTC system (TC/EA) to determine the best method to measure the δ18O values of nitrogen‐rich organic substrates including: (1) 0.6 and 1.5 m 5 Å molecular sieve GC columns; (2) reduction of N2 peak via He dilution; and (3) diversion of N2 to waste via an automated four‐port valve. These methods were applied to caffeine (IAEA‐600), glycine, 4‐nitroacetanilide, pentaerythritol tetranitrate (PETN) and cyclotrimethylene trinitramine (RDX), as well as pure and sodium azide‐doped benzoic acid (IAEA‐601) and sucrose (IAEA‐CH6).

RESULTS

The efficiency of N2 production in the HTC interface was highly variable among these compounds. Both the longer column and the dilutor improved, but did not eliminate, the adverse effects of nitrogen.

CONCLUSIONS

The diversion of N2 adequately addressed the nitrogen‐induced problems as indicated by: (1) consistent m/z 30 background offset between reference and sample CO for both N‐free and N‐rich materials; (2) production of the highest δ18O values; and (3) high correlation between the increase in the δ18O values relative to the GC‐only measurements and the N2 peak area. Additional validation would require N‐rich oxygen isotope standards for inter‐laboratory comparisons. Further, more stringent methodology may improve the poor inter‐laboratory δ18O reproducibility of IAEA‐600. Published in 2012 by John Wiley & Sons, Ltd.
Generation of negative ions from SF6 gas by means of hot surface ionization
Authors: Pelc Andrzej
Published: February 2012

RATIONALE

Sulfur hexafluoride (SF6) is a man‐made compound with many industrial applications. This compound is also one of the most powerful greenhouse gases with a relatively long atmospheric lifetime. Therefore, it is important to investigate processes leading to SF6 decomposition.

METHODS

A magnetic sector mass spectrometer with a thermoemission gaseous ion source was used in this study. The filament temperature was changed and monitored pyrometrically during the course of the studies. In the hot surface ionization process, negative ions may be generated both by free electron attachment to a molecule and by thermal dissociation followed by electron capture to the one of the fragments formed.

RESULTS

Eight ion species: SF5–, F–, SF6–, SF4–, SF3–, SF2–, SF– and F2–, with ion current intensities ratios of 1000:200:100:10:5:0.5:0.5:0.05, respectively, were detected. The filament temperature dependencies of the SF5–, F–, SF6–, SF4– ion current intensities were measured. The optimal temperatures at which the maximum of the ion current intensity is observed were estimated in the 1830–2000 ± 10 °C range. The formation of F2– ions is probably disturbed by a dissociation process at high temperatures.

CONCLUSIONS

Negative surface ionization on the hot filament is a relatively simple and effective method for carrying out negative ion formation studies. Eight SF6 decomposition channels leading to the formation of negative ions have been detected and analyzed using this technique. Copyright © 2012 John Wiley & Sons, Ltd.
In vitro three‐dimensional aortic vasculature modeling based on sensor fusion between intravascular ultrasound and magnetic tracker
Authors: Shi Chaoyang , Tercero Carlos , Ikeda Seiichi , Ooe Katsutoshi , Fukuda Toshio , Komori Kimihiro , Yamamoto Kiyohito
Published: February 2012

Background

It is desirable to reduce aortic stent graft installation time and the amount of contrast media used for this process. Guidance with augmented reality can achieve this by facilitating alignment of the stent graft with the renal and mesenteric arteries.

Methods

For this purpose, a sensor fusion is proposed between intravascular ultrasound (IVUS) and magnetic trackers to construct three‐dimensional virtual reality models of the blood vessels, as well as improvements to the gradient vector flow snake for boundary detection in ultrasound images. In vitro vasculature imaging experiments were done with hybrid probe and silicone models of the vasculature.

Results

The dispersion of samples for the magnetic tracker in the hybrid probe increased less than 1 mm when the IVUS was activated. Three‐dimensional models of the descending thoracic aorta, with cross‐section radius average error of 0.94 mm, were built from the data fusion.

Conclusion

The development of this technology will enable reduction in the amount of contrast media required for in vivo and real‐time three‐dimensional blood vessel imaging. Copyright © 2012 John Wiley & Sons, Ltd.
Effect of post‐deposition annealing on surface morphology and gas sensing properties of palladium phthalocyanine thin films
Authors: Jafari Mohammad Javad , Azim‐Araghi Mohammad Esmaeil , Barhemat Samira , Riyazi Sobhenaz
Published: February 2012

The effect of post‐deposition annealing on surface morphology and gas sensing properties of palladium phthalocyanine (PdPc) nanostructured thin films has been studied. PdPc thin films were deposited on polyborosilicate substrate by thermal evaporation technique at room temperature. The surface morphology of thin films was investigated by SEM, X‐ray diffraction, and optical absorption. X‐ray diffraction patterns showed a phase transition from α to β based on post‐deposition annealing at temperatures above 200 °C. The SEM and optical absorption confirmed that annealing strongly influenced the surface morphology of nanostructured thin films. Sandwich devices (Au|PdPc|Al) were fabricated and exposed to different concentrations of NO2 and NH3 as oxidizing and reducing gases at different temperatures, and the sensitivity of devices were obtained versus gases. Obtained results showed α‐PdPc thin film devices had higher sensitivity in comparison with devices in β‐phase. In particular, it was found that the sensitivity of devices is temperature dependent and the best operating temperature range of devices was measured at about 90–100 °C. Devices showed good reversibility, response, and recovery time at room temperature. Finally, the stability of sensors was investigated for a period of about 1 year; results showed that the sensors were stable for 2 months and lost about 30% of their sensitivity after 1 year. Copyright © 2012 John Wiley & Sons, Ltd.
Comparison of C60 and GCIB primary ion beams for the analysis of cancer cells and tumour sections
Authors: Fletcher John S. , Rabbani Sadia , Barber Andrew M. , Lockyer Nicholas P. , Vickerman John C.
Published: February 2012

We have implemented a gas cluster ion beam (GCIB) system developed by Ionoptika Ltd (Southampton, UK) with sufficient control to allow us to exploit the unique capabilities of our J105 instrument for imaging and depth profiling. The J105 allows us to use the GCIB as continuous primary ion beam, thereby overcoming the issues associated with pulsing these slow moving, mixed species beams. We have performed a direct comparison with C60 ions on the same samples in the same instrument. The GCIB beams are more difficult to focus than the C60+ ion beam, making single‐cell imaging difficult, although spot sizes of 15–20 µm are readily obtainable for Ar1000 and Ar2000, providing good resolution for larger area imaging on tissue section/biopsy samples. In this paper, we present results from the assessment of these new beams as primary ions for the analysis of ‘real’, complex biological systems. Initial spectra and those following increased primary ion bombardment were compared for in vitro cultured cells deposited on silicon and cryo‐sectioned tumour samples originating in vivo. Ar1000+ and Ar2000+ showed increased persistence of the signals from intact molecular ions of phospholipids and a reduction in the accumulation of chemical background noise compared with C60+ analysis. Copyright © 2012 John Wiley & Sons, Ltd.
Summary of ISO/TC 201 Standard: ISO 18115‐1:2010 – surface chemical analysis – vocabulary – general terms and terms used in spectroscopy
Authors: Seah M P
Published: February 2012

This International Standard revises ISO 18115:2001 and the two subsequent amendments by bringing the material up to date and separating out the general terms and terms used in spectroscopy into Part 1, and terms relating to scanning probe microscopy into Part 2. This part, Part 1, covers 548 terms used in Auger electron spectroscopy, elastic peak electron spectroscopy, reflected electron energy loss spectroscopy, secondary ion mass spectrometry, ultra‐violet photoelectron spectroscopy, X‐ray photoelectron spectroscopy, and so on, as well as 52 acronyms. The terms cover words or phrases used in describing the samples, instruments, and theoretical concepts involved in surface chemical analysis. Copyright © 2012 Crown copyright.
Developing a Millifluidic Platform for the Synthesis of Ultrasmall Nanoclusters: Ultrasmall Copper Nanoclusters as a Case Study
Authors: Biswas Sanchita , Miller Jeffrey T. , Li Yuehao , Nandakumar Krishnaswamy , Kumar Challa S. S. R.
Published: February 2012

The future of lab‐on‐a‐chip devices for the synthesis of nanomaterials hinges on the successful development of high‐throughput methods with better control over their size. While significant effort in this direction mainly focuses on developing “difficult to fabricate” complex microfluidic reactors, scant attention has been paid to the “easy to fabricate” and simple millifluidic systems that could provide the required control as well as high throughput. By utilizing numerical simulation of fluids within the millifluidic space at different flow rates, the results presented here show velocity profiles and residence time distributions similar to the case of microfluidics. By significantly reducing the residence time and residence time distribution, a continuous flow synthesis of ultrasmall copper nanoclusters (UCNCs) with exceptional colloidal stability is achieved. In‐situ synchrotron‐radiation‐based X‐ray absorption spectroscopy (XAS) reveal that the as‐prepared clusters are about 1 nm, which is further supported by transmission electron microscopy and UV–vis spectroscopy studies. The clusters reported here are the smallest ever produced using a lab‐on‐a‐chip platform. When supported on silica, they are found to efficiently catalyze C–H oxidation reactions, hitherto unknown to be catalyzed by Cu. This work suggests that a millifluidic platform can be an inexpensive, versatile, easy‐to‐use, and powerful tool for nanoparticle synthesis in general, and more specifically for ultrasmall nanoclusters (UNCs).
Charles Horton Cooley, Pragmatist or Belletrist? The Complexity of Influence and the Decentering of Intellectual Traditions
Authors: Jacobs Glenn
Published: February 2012

This essay treats recent attempts to identify symbolic interaction (SI) founding theorist Charles Horton Cooley as a pragmatist sociologist exemplifying, and even influenced by, the pragmatism of Charles Saunders Peirce, as an example of the American exceptionalist character of SI. Beginning with Cooley's creative approach to conceptualizing the social, these attempts are scrutinized and measured against the contention that Cooley's thought can be equally if not more understood as a product of influence of the literary essay tradition. A close reading is given of the concordance of his personal journal with a selection of his published writings concerning the influence of members of Cooley's essayistic “genre matrix” – Emerson, Montaigne, and Walter Pater – on the development of his intellectual self and thought. Further substantiation is supplied by an analysis of the essayistic influence on Cooley's rigorous treatment of qualitative methodology. It is concluded that a decentered positioning of Cooley's work is preferable to a single‐origin one.
Pharmacological characterization of the norepinephrine and dopamine reuptake inhibitor EB‐1020: Implications for treatment of attention‐deficit hyperactivity disorder
Authors: Bymaster Frank P. , Golembiowska Krystyna , Kowalska Magdalena , Choi Yong Kee , Tarazi Frank I.
Published: February 2012

We report on the pharmacological, behavioral, and neurochemical characterization of a novel dual norepinephrine (NE)/dopamine (DA) transporter inhibitor EB‐1020 (1R,5S)‐1‐(naphthalen‐2‐yl)‐3‐azabicyclo[3.1.0]hexane HCl). EB‐1020 preferentially inhibited monoamine reuptake in cloned cell lines transfected with human transporters with IC50 values of 6 and 38, respectively, for NE and DA transporters. In microdialysis studies, EB‐1020 markedly increased NE, and DA concentrations levels in rat prefrontal cortex in vivo with peak increases of 375 and 300%, respectively with the greatest effects on NE, and also increased DA extracellular concentrations in the striatum to 400% of baseline concentrations. Behavioral studies demonstrated that EB‐1020 dose‐dependently decreased immobility in the mouse tail suspension test of depression to 13% of control levels, and did not stimulate locomotor activity in adult rats in the optimal dose range. EB‐1020 dose‐dependently inhibited locomotor hyperactivity in juvenile rats lesioned with the neurotoxin 6‐hydroxydopamine (100 μg intracisternally) as neonates; a well‐established animal model for attention‐deficit hyperactivity disorder (ADHD). These data suggest that EB‐1020 mediates its actions by stimulating NE and DA neurotransmission, which are typically impaired in ADHD. Synapse, 2012. © 2012 Wiley Periodicals, Inc.