bluuebunny/crossref_metadata_2025 huggingface dataset:
Miscibility studies of xanthan gum with gelatin in dilute solution
Authors: Basavaraju K. C. , Jayaraju J. , Rai S. K. , Damappa T.
Published: May 2008

Miscibility of polysaccharide‐based natural polymer, xanthan gum with gelatin in 0.1M NaCl medium was investigated using viscosity, ultrasonic, and refractive index technique. The effect of temperature on the miscibility was studied at 30 and 40°C. The interaction parameters “μ” and “α” were calculated based on the Chee (Eur Polymer J 1990, 26, 423) and Sun et al. (Eur Polym J 1992, 28, 1259) approach. The obtained values indicated that the blend is miscible when the xanthan gum is 70% (V/V) or more at 30°C, and 40% (V/V) or more at 40°C. The corresponding variation of refractive index and ultrasonic velocity also supports the Sun et al. approach. The compatibility between these two polymers was further confirmed by SEM and FTIR. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Characteristics of the sorption of water and an ethanol/water solution by light‐cured copolymers of 2‐hydroxyethyl methacrylate with dental dimethacrylates
Authors: Sideridou Irini D. , Karabela Maria M.
Published: May 2008

This work concerns the synthesis of copolymers of 2‐hydroxyethyl methacrylate (HEMA) and the dimethacrylates bisphenol A glycol dimethacrylate, bisphenol ethoxylated dimethacrylate, urethane dimethacrylate, and triethylene glycol dimethacrylate (50/50 mol/mol) because of their potential use in contemporary dentine adhesives. Copolymerization was carried out at room temperature with visible light (λmax = 470 nm), with the system camphorquinone/N,N‐dimethylaminoethyl methacrylate being used as the photoinitiator. The behavior of these copolymers under oral conditions is of great concern. Thus, the sorption/desorption kinetics of water and a 75 vol % ethanol/water solution (which is an oral/food simulating liquid) by these copolymers were studied. The maximum amount of sorbed/desorbed liquid, solubility, and diffusion coefficient of each liquid were determined. The amount of sorbed liquid and solubility of the copolymers depended on both the structure of the copolymer and the nature of the solvent. The amount of water sorbed by the copolymers and their diffusion coefficients were much lower than those of the HEMA homopolymer but closer to those of the homopolymers of the dimethacrylate comonomers. All the copolymers sorbed a higher amount of the ethanol/water solution than water. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Conformation and deformation of linear macromolecules in concentrated solutions and melts in the self‐avoiding random walks statistics
Authors: Medvedevskikh Yu. G.
Published: May 2008

A strict statistics of self‐avoiding random walks in the d‐measured lattice and continuous space for intertwining chains in the concentrated solutions and melts was proposed. On the basis of this statistics the thermodynamics of conformation and isothermal and adiabatic deformation of intertwining chains was described. The equation of conformational state has been obtained. It was shown that in the field of chains overlap they are stretched increasing its conformational volume. In this volume there are other chains with the formation of m‐ball. Free energy of a chain conformation does not depend upon the fact, if the chains intertwined or they are isolated in the m‐ball. Mixing entropy is responsible to the chains interweaving in the m‐ball. Dependencies of the conformational radius, free energy, and conformation pressure on respective concentration of polymeric chains have been determined. Using the thermodynamics of intertwining polymeric chains of m‐ball conformational state and also the laws of isotropic media deformation into linear differential form the theoretical expressions for elasticity modules (namely, volumetric volume, Young's module and shift's module) and for the main tensions appearing at the equilibrium deformation of the m‐ball were obtained. Poisson's coefficient is a function only on the Euclidean's space and for the real three‐dimensional space is equal to 3/8. A simple model explaining the tensile strength of the m‐ball by the chains intertwining effect and, thereafter by the loss of the mixing entropy, but not by the chemical bonds breaking was proposed. Calculations of the elastic properties, the main tensions, and tensile strength of natural rubber carried out without using the empirical adjusting parameters are in good agreement with the experimental data. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
High resolution imaging of the knee on 3‐Tesla MRI: A pictorial review
Authors: Griffin N. , Joubert I. , Lomas D.J. , Bearcroft P.W.P. , Dixon A.K.
Published: May 2008

The recent introduction of 3‐Tesla MRI offers substantial advances in musculoskeletal applications. High resolution images can now be obtained with shorter data acquisition times. This article provides a pictorial review of 3‐Tesla imaging in the knee with descriptions of both normal anatomy and the more common lesions involving the menisci, ligaments, and articular cartilage. A discussion of the issues associated with imaging at higher field strengths is also included. Clin. Anat. 21:374–382, 2008. © 2008 Wiley‐Liss, Inc.
Structural, Magnetic Coupling and Oxidation State Trends in Models of the CaMn4 Cluster in Photosystem II
Authors: Petrie Simon , Stranger Rob , Pace Ron J.
Published: May 2008

Density functional theory calculations are reported on a set of isomeric structures I, II and III that share the structural formula [CaMn4C9H10N2O16]q+⋅(H2O)3 (q=−1, 0, 1, 2, 3). Species I has a skeletal structure, which has been previously identified as a close match to the ligated CaMn4 cluster in Photosystem II, as characterized in the most recent 3.0 Å crystal structure. Structures II and III are rearrangements of I, which largely retain that model's bridging ligand framework, but feature metal atom positions broadly consistent with, respectively, the earlier 3.5 and 3.2 Å crystal structures for the Photosystem II water‐oxidising complex (WOC). Our study explores the influence of the cluster charge state (and hence S state) on several important properties of the model structures; including the relative energies of the three models, their interconversion, trends in the individual Mn oxidation states, preferred hydration sites and favoured modes of magnetic coupling between the manganese atoms. We find that, for several of the explored cluster charge states, modest differences in the bridging‐ligand geometry exert a powerful influence over the individual manganese oxidation states, but throughout these states the robustness of the tetrahedron formed by the Ca and three of the Mn atoms remains a significant feature and contrasts with the positional flexibility of the fourth Mn atom. Although structure I is lowest in energy for most S states, the energy differences between structures for a given S state are not large. Overall, structure II provides a better match for the EXAFS derived metal–metal distance parameters for the earlier S states (S0 to S2), but not for S3 in which a significant structural change is observed experimentally. In this S state structure III provides a closer fit. The implications of these results, for the possible action of the WOC, are discussed.
Long‐term results of the treatment of patients with mantle cell lymphoma with cladribine (2‐CDA) alone (95‐80‐53) or 2‐CDA and rituximab (N0189) in the North Central Cancer Treatment Group
Authors: Inwards David J. , Fishkin Paul A. S. , Hillman David W. , Brown David W. , Ansell Stephen M. , Kurtin Paul J. , Fonseca Rafael , Morton Roscoe F. , Veeder Michael H. , Witzig Thomas E.
Published: May 2008

BACKGROUND.

The objective of this study was to test cladribine (2‐CDA) alone and in combination with rituximab in patients with mantle cell lymphoma (MCL).

METHODS.

Patients with MCL were treated on 2 sequential trials. In Trial 95‐80‐53, patients received 2‐CDA as initial therapy or at relapse. In Trial N0189, patients received combination 2‐CDA and rituximab as initial therapy. In both trials, 2‐CDA was administered at a dose of 5 mg/m2 intravenously on Days 1 through 5 every 4 weeks for 2 to 6 cycles, depending on response. In Trial N0189, rituximab 375 mg/m2 was administered on Day 1 of each cycle.

RESULTS.

Results were reported for 80 patients. Twenty‐six previously untreated patients and 25 patients who had recurrent disease with a median age of 68 years received single‐agent 2‐CDA. The overall response rate (ORR) was 81% with 42% complete responses (CRs) in the previously untreated group. The median progression‐free survival (PFS) was 13.6 months (95% confidence interval [95% CI], 7.2‐22.1 months), and 81% of patients remained alive at 2 years. The ORR was 46% with a 21% CR rate in the recurrent disease group. The median PFS was 5.4 months (95% CI, 4.6‐13.1 months), and 36% of patients remained alive at 2 years. Twenty‐nine eligible patients with a median age of 70 years received 2‐CDA plus rituximab. The ORR was 66% (19 of 29 patient), and the CR rate was 52% (15 of 29 patients). The median duration of response for patients who achieved a CR had not been reached at the time of the current report, and only 3 of the patients who achieved a CR developed recurrent disease at a median follow‐up of 21.5 months.

CONCLUSIONS.

2‐CDA had substantial single‐agent activity in both recurrent and untreated MCL, and the results indicated that it may be administered safely to elderly patients. The addition of rituximab to 2‐CDA may increase the duration of response. Cancer 2008. © 2008 American Cancer Society.
Multiple‐dose granulocyte‐macrophage–colony‐stimulating factor plus 23‐valent polysaccharide pneumococcal vaccine in patients with chronic lymphocytic leukemia
Authors: Safdar Amar , Rodriguez Gilhen H. , Rueda Adriana M. , Wierda William G. , Ferrajoli Alessandra , Musher Daniel M. , O'Brien Susan , Koller Charles A. , Bodey Gerald P. , Keating Michael J.
Published: May 2008

BACKGROUND.

For the current study, the authors sought to determine whether administration of multiple‐dose granulocyte‐macrophage–colony‐stimulating factor (GM‐CSF) could improve response to standard 23‐valent polysaccharide pneumococcal vaccine (PPV) in patients with chronic lymphocytic leukemia (CLL).

METHODS.

Patients were allocated randomly to receive PPV either alone or with 3 doses of GM‐CSF (250 μg) given before or after vaccination. Serum was obtained before, 4 weeks after, and 12 weeks after vaccination for antibody determination. Thirty‐two patients with CLL were given PPV. They were randomized to receive 3 doses of GM‐CSF either before or after vaccination or to receive no GM‐CSF.

RESULTS.

A 4‐fold rise in immunoglobulin G (IgG) to capsular polysaccharides from Streptococcus pneumoniae types 4, 6B, 9V, 14, 19F, and 23F occurred in <10% of patients in each of the 3 groups. There were no differences in geometric mean IgG levels in any of the 3 groups 4 weeks or 12 weeks after vaccination.

CONCLUSIONS.

In patients with CLL, the response to pure polysaccharide pneumococcal vaccine was low despite immune enhancement with multiple doses of GM‐CSF. In all patients, reactogenicity was minor. Cancer 2008. © 2008 American Cancer Society.
Temperature Dependence of Interactions between Stable Piperidine‐1‐yloxyl Derivatives and an Ionic Liquid
Authors: Strehmel Veronika , Rexhausen Hans , Strauch Peter , Görnitz Eckhard , Strehmel Bernd
Published: May 2008

2,2,6,6‐Tetramethylpiperidine‐1‐yloxyl derivatives substituted with either hydrogen bonding [‐OH, ‐OSO3H] or ionic [‐OSO3−Na+, ‐OSO3−K+, N+(CH3)3I−, N+(CH3)3 N−(SO2‐CF3)2] substituents are investigated in 1‐butyl‐3‐methylimidazolium tetrafluoroborate over a wide temperature range covering both glassy and viscous states. The Vogel–Fulcher–Tammann equation describes the temperature dependence of the ionic liquid viscosity. Quantum chemical calculations of the spin probes at the UB3LYP/6‐311(2d,p++) level are done to describe the dependence of the spin density on nitrogen on the substitution pattern of the 4‐position of the probe. The results of these calculations are also used to understand the experimental results obtained by applying the Spernol–Gierer–Wirtz theory to analyze the viscosity dependence of the rotational correlation time of the spin probes. Significant differences are found between 2,2,6,6‐tetramethylpiperidine‐1‐yloxyl and its derivatives containing substituents that are able to form hydrogen bonds with the ionic liquid. Moreover, derivatives substituted with ionic groups at the 4‐position have a large effect on temperature‐induced solvent viscosity, as this is particularly dependent on the nature of the substituent at the 4‐position. These dependencies include the temperature region that can be used to describe interactions between the spin probes and the ionic liquid, diffusion into the free volume during non‐activated (neutral spin probes) and activated (charged spin probes) processes. Additional parameters are the radii of the ionic liquid and the spin probes, which are calculated and measured approximately. In addition, the temperature dependence of the isotropic hyperfine coupling constants of the spin probes results in information about the micropolarity of the ionic liquid. At room temperature, this is comparable to that of the solvent dimethylsulfoxide.
Interactions of Aromatic Heterocycles with Water: The Driving Force from Free‐Jet Rotational Spectroscopy and Model Electrostatic Calculations
Authors: Maris Assimo , Melandri Sonia , Miazzi Marta , Zerbetto Francesco
Published: May 2008

The interaction of isolated aromatic nitrogen atoms with water is explored within free jets by using rotational spectroscopy. To the existing data on diazines, we add the case of the 1:1 complex of 1,3,5‐triazine and water (where water donates a proton to one of the nitrogen heterocyclic atoms to form a planar adduct). An electrostatic model based on distributed multipoles accurately reproduces the structures of the four azine–water complexes and allows us to understand the forces that stabilize these structures. The applied intermolecular potential allows us to estimate the changes in the thermodynamic functions of the complexes—compared to the separated constituents—and evaluate the temperature at which the complexes are stable under standard conditions.
Stereoselective Synthesis of Quaternary Proline Analogues
Authors: Calaza M. Isabel , Cativiela Carlos
Published: May 2008

This review describes available methods for the diastereoselective and asymmetric synthesis of quaternary prolines. The focus is on the preparation of α‐functionalized prolines in which the pyrrolidine moiety is not embedded in a polycyclic frame. The diverse synthetic approaches are classified according to the bond that is formed to complete the quaternary skeleton.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Short‐term forecasts of euro area real GDP growth: an assessment of real‐time performance based on vintage data
Authors: Diron Marie
Published: May 2008

Forecasters commonly predict real gross domestic product growth from monthly indicators such as industrial production, retail sales and surveys, and therefore require an assessment of the reliability of such tools. While forecast errors related to model specification and unavailability of data in real time have been assessed, the impact of data revisions on forecast accuracy has seldom been evaluated, especially for the euro area. This paper proposes to evaluate the contributions of these three sources of forecast error using a set of data vintages for the euro area. The results show that gains in accuracy of forecasts achieved by using monthly data on actual activity rather than surveys or financial indicators are offset by the fact that the former set of monthly data is harder to forecast and less timely than the latter set. These results provide a benchmark which future research may build on as more vintage datasets become available. Copyright © 2008 John Wiley & Sons, Ltd.
Combining forecasts using optimal combination weight and generalized autoregression
Authors: Kurz‐Kim Jeong‐Ryeol
Published: May 2008

In this paper, we consider a combined forecast using an optimal combination weight in a generalized autoregression framework. The generalized autoregression provides not only a combined forecast but also an optimal combination weight for combining forecasts. By simulation, we find that short‐ and medium‐horizon (as well as partly long‐horizon) forecasts from the generalized autoregression using the optimal combination weight are more efficient than those from the usual autoregression in terms of the mean‐squared forecast error. An empirical application with US gross domestic product confirms the simulation result. Copyright © 2008 John Wiley & Sons, Ltd.
Excellent outcome following down-staging of hepatocellular carcinoma prior to liver transplantation: An intention-to-treat analysis
Authors: Yao Francis Y. , Kerlan Robert K. , Hirose Ryutaro , Davern Timothy J. , Bass Nathan M. , Feng Sandy , Peters Marion , Terrault Norah , Freise Chris E. , Ascher Nancy L. , Roberts John P.
Published: May 2008

We previously reported encouraging results of down-staging of hepatocellular carcinoma (HCC) to meet conventional T2 criteria (one lesion 2–5 cm or two to three lesions <3 cm) for orthotopic liver transplantation (OLT) in 30 patients as a test of concept. In this ongoing prospective study, we analyzed longer-term outcome data on HCC down-staging in a larger cohort of 61 patients with tumor stage exceeding T2 criteria who were enrolled between June 2002 and January 2007. Eligibility criteria for down-staging included: (1) one lesion >5 cm and up to 8 cm; (2) two to three lesions with at least one lesion >3 cm and not exceeding 5 cm, with total tumor diameter up to 8 cm; or (3) four to five lesions with none >3 cm, with total tumor diameter up to 8 cm. A minimum observation period of 3 months after down-staging was required before OLT. Tumor down-staging was successful in 43 patients (70.5%). Thirty-five patients (57.4%) had received OLT, including two who had undergone live-donor liver transplantation. Treatment failure was observed in 18 patients (29.5%), primarily due to tumor progression. In the explant of 35 patients who underwent OLT, 13 had complete tumor necrosis, 17 met T2 criteria, and five exceeded T2 criteria. The Kaplan-Meier intention-to-treat survival at 1 and 4 years after down-staging were 87.5% and 69.3%, respectively. The 1-year and 4-year posttransplantation survival rates were 96.2% and 92.1%, respectively. No patient had HCC recurrence after a median posttransplantation follow-up of 25 months. The only factor predicting treatment failure was pretreatment alpha-fetoprotein >1,000 ng/mL.

Conclusion:

Successful down-staging of HCC can be achieved in the majority of carefully selected patients and is associated with excellent posttransplantation outcome. (Hepatology 2008.)
Changing patterns of Hodgkin lymphoma incidence in Singapore
Authors: Hjalgrim Henrik , Seow Adeline , Rostgaard Klaus , Friborg Jeppe
Published: May 2008

A bimodal age‐specific incidence pattern with a relatively high proportion of cases occurring in adolescents and young adults is a hallmark of Hodgkin lymphoma (HL) epidemiology in Western industrialized countries. The young adult incidence peak is believed to reflect the association between HL risk in young adults and an affluent childhood socioeconomic environment. However, the dynamic development of the young adult incidence peak following socioeconomic development implied by this interpretation has scarcely been demonstrated in a single population over time. We, therefore, analyzed incidence patterns of HL in Singapore between 1968 and 2004, during which time period a socioeconomic transition towards Western World lifestyles took place. As hypothesized a HL incidence peak emerged among adolescents and young adults in Singapore. Thus, in the age groups 15–19 and 20–24 years incidence rates increased annually by 7.0% (95% confidence interval 3.4%–10.7%) and 3.4% (0.1%–6.8%), respectively, in men and by 13.7% (9.1%–18.6%) and 12.2% (7.8–16.8%), respectively, in women between 1968 and 2004. However, the incidence peak remained considerably lower than what can be observed in young adults in the Western World. It remains to be determined to what extent the current lower incidence of HL in young Asian adults should be attributed to birth cohort phenomena, as would be suggested by continued increase in incidence, and to ethnic variation in HL susceptibility between Asian and non‐Asian populations, respectively. © 2008 Wiley‐Liss, Inc.
Growth inhibition of colon cancer cells by polyisoprenylated benzophenones is associated with induction of the endoplasmic reticulum response
Authors: Protiva Petr , Hopkins Michael E. , Baggett Scott , Yang Hui , Lipkin Martin , Holt Peter R. , Kennelly Edward J. , Bernard Weinstein I.
Published: May 2008

Polyisoprenylated benzophenones derived from Garcinia xanthochymus have cytotoxic activity in vitro and antitumor activity in rodent models, but the mechanism is unknown. The purpose of our study was to examine in parallel molecular pathways that are targeted by 3 Garcinia‐derived benzophenones‐xanthochymol (X), guttiferone E (GE) and guttiferone H (GH), in 3 human colon cancer cell lines, HCT116, HT29 and SW480. The IC50 concentrations were determined and the cells were then treated with X, GE or GH at their respective IC50 or IC50x2 concentrations. Effects on the cell cycle, mitochondrial membrane potential and apoptosis were assessed by flow cytometry and caspase activation. Changes in gene expression were assessed with Illumina 24 K gene arrays. We found that X, GE and GH induced loss of mitochondrial membrane potential and G1 arrest at their IC50 concentrations and induced caspase activation at IC50 × 2 concentrations. An analysis of the changes in gene expression revealed that with all 3 compounds and all 3 cell lines there was a marked increase in expression of several genes, including XBP1, ATF4 and DDIT3/CHOP, which are components of the endoplasmic reticulum stress response. The DDIT4/REDD1 gene, an inhibitor of the mTOR survival pathway, was also up‐regulated. Therefore, X, GE and GH appear to inhibit the growth of human colon cancer cells, at least in part, by activating the endoplasmic reticulum stress response and inhibiting the mTOR cell survival pathway. These combined effects may contribute to the anticancer activity of these novel compounds. © 2008 Wiley‐Liss, Inc.
IFN‐γ withdrawal after immunotherapy potentiates B16 melanoma invasion and metastasis by intensifying tumor integrin αvβ3 signaling
Authors: Gong Wei , Zhang Gui‐Mei , Liu Yi , Lei Zhang , Li Dong , Yuan Ye , Huang Bo , Feng Zuo‐Hua
Published: May 2008

Immunotherapy can effectively suppress tumor, yet complete tumor eradication occurs infrequently. The metastatic potential of remnant tumor cells after immunotherapy and the underlying mechanisms have not been fully elucidated. Here, we report that the termination of immunotherapy strikingly increases the metastatic potential of remnant melanoma. This is mainly due to the withdrawal of IFN‐γ after immunotherapy. The relief of IFN‐γ stress led to the increase of αvβ3 integrin expression in B16 cells, which increased the adhesion of B16 cells to fibrinogen, fibronectin and laminin. Through αvβ3 signaling, the activation of FAK, upregulation of cdc2, production of active MMP‐2 and MMP‐9 and actin polymerization were intensified in B16 cells stimulated with ECM molecules 24 h after the withdrawal of IFN‐γ. The i.v. injection of such tumor cells into mice resulted in more metastatic tumor nodes in lung and shortened the survival of mice. The pitfall of immunotherapy termination can be remedied by the administration of recombinant CBD‐HepII polypeptide of fibronectin, which effectively inhibits αvβ3 signaling. These findings suggest that the risk of tumor metastasis can be increased after the termination of immunotherapy, due to the withdrawal of IFN‐γ and that targeting αvβ3 signaling pathway can improve the therapeutic effect of immunotherapeutic approaches by reducing such metastatic risk. © 2008 Wiley‐Liss, Inc.
The roles of surface chemistry and topography in the strength and rate of osseointegration of titanium implants in bone
Authors: Sul Young‐Taeg , Kang Byung‐Soo , Johansson Carina , Um Heung‐Sik , Park Chan‐Jin , Albrektsson Tomas
Published: May 2008

The present study investigated the effects of surface chemistry and topography on the strength and rate of osseointegration of titanium implants in bone. Three groups of implants were compared: (1) machine‐turned implants (turned implants), (2) machine‐turned and aluminum oxide‐blasted implants (blasted implants), and (3) implants that were machine‐turned, aluminum oxide‐blasted, and processed with the micro‐arc oxidation method (Mg implants). Three and six weeks after implant insertion in rabbit tibiae, the implant osseointegration strength and rate were evaluated. Surface chemistry revealed characteristic differences of nine at.% Mg for Mg implants and 11 at.% Al for blasted implants. In terms of surface roughness, there was no difference between Mg implants and blasted implants in developed surface ratio (Sdr; p = 0.69) or summit density (Sds; p = 0.96), but Mg implants had a significantly lower arithmetic average height deviation (Sa) value than blasted implants (p = 0.007). At both 3 and 6 weeks, Mg implants demonstrated significantly higher osseointegration strength compared with turned (p = 0.0001, p = 0.0001) and blasted (p = 0.0001, p = 0.035) implants, whereas blasted implants showed significantly higher osseointegration than turned implants at 6 weeks (p = 0.02) but not at 3 weeks (p = 0.199). The present results not only support the hypothesis that biochemical bonding facilitates rapid and strong integration of implants in bone, but also provide evidence for biochemical bonding theory previously proposed by Sul. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Maya blue–green pigments found in Calakmul, Mexico: a study by Raman and UV‐visible spectroscopy
Authors: Garcia Moreno Renata , Strivay David , Gilbert Bernard
Published: May 2008

After more than two decades of fieldwork in the Maya archaeological site of Calakmul, Mexico, numerous remnants of blue and green pigments have been reported on wall paintings, as well as on funerary paraphernalia, such as masks, miniatures and vases. The importance of these pigments is linked to the sacred values that Maya people associate with blue and green colours since pre‐Columbian times. These hues symbolise water, and are therefore associated with fertility and regeneration. This paper aims to perform a survey of the blue and green pigments used in the Early Classic and Late Classic periods in Calakmul (300–850 A.D.), in order to have a better understanding of their chemical composition and origin. Analyses were performed on microsamples using Raman and UV‐visible spectroscopies to evaluate the possibilities that these techniques can offer in future in situ researches on Mesoamerican archaeological materials and objects. With these analyses, we have documented a large blue–green chromatic palette, which includes the earliest Blue Maya and Green Maya known to date, as well as malachite, pseudomalachite and an unknown‐up‐to‐now blue‐green mineral pigment, veszelyite, used specifically for ritual objects. The results indicate a careful selection of imported products and the mastering of a complex ancient Maya pictorial tradition. Copyright © 2008 John Wiley & Sons, Ltd.
15N1H and 15N–13C couplings in 15N‐enriched dihydroxamic acids
Authors: Schraml Jan , Cigler Petr
Published: May 2008

15N‐enriched dihydroxamic acids (HONHCO(CH2)nCONHOH, n = 0, 1, and 2) were prepared and their spectra NMR (1H, 13C, 15N) recorded in dimethyl sulfoxide (DMSO) solutions with the aim of determining 15N coupling constants (15N1H and 15N13C). The results supplement chemical shifts published earlier and yield additional support to the structural conclusions derived from other NMR parameters. Notably, no trace of hydroximic structures could be found in the 15N NMR spectra of these acids. The values of 15N13C coupling constants backed by theoretical calculations support the assignments made earlier for all of the major conformers and for the minor conformer of succinohydroxamic acid. The enrichment revealed that the minor component of malonodihydroxamic acid solution previously considered to be the ZE conformer is in fact the monohydroxamic acid (HOOCCH2CONHOH). Copyright © 2008 John Wiley & Sons, Ltd.
Molecular modeling simulation and experimental measurements to characterize chitosan and poly(vinyl pyrrolidone) blend interactions
Authors: Suknuntha Krit , Tantishaiyakul Vimon , Vao‐Soongnern Visit , Espidel Youssef , Cosgrove Terrence
Published: May 2008

Blends of chitosan and poly(vinyl pyrrolidone) (PVP) have a high potential for use in various biomedical applications and in advanced drug‐delivery systems. Recently, the physical and chemical properties of these blends have been extensively characterized. However, the molecular interaction between these two polymers is not fully understood. In this study, the intermolecular interaction between chitosan and PVP was experimentally investigated using 13C cross‐polarization magic angle‐spinning nuclear magnetic resonance (13C CP/MAS NMR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). According to these experimental results, the interaction between the polymers takes place through the carbonyl group of PVP and either the OHC6, OHC3, or NHC2 of chitosan. In an attempt to identify the interacting groups of these polymers, molecular modeling simulation was performed. Molecular simulation was able to clarify that the hydrogen atom of OHC6 of chitosan was the most favorable site to form hydrogen bonding with the oxygen atom of CO of PVP, followed by that of OHC3, whereas that of NHC2 was the weakest proton donor group. The nitrogen atom of PVP was not involved in the intermolecular interaction between these polymers. Furthermore, the interactions between these polymers are higher when PVP concentrations are lower, and interactions decrease with increasing amounts of PVP. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1258–1264, 2008
Morphology evolution of nanocomposites based on poly(phenylene sulfide)/poly(butylene terephthalate) blend
Authors: Wu Defeng , Wu Lanfeng , Zhang Ming , Zhou Weidong , Zhang Yisheng
Published: May 2008

Poly(phenylene sulfide) (PPS)/poly(butylene terephthalate) (PBT) (60/40 w/w) blend nanocomposites (PPS/PBTs) were prepared by direct melt compounding of PPS, PBT, and organoclay. The morphology and rheology of PPS/PBTs were investigated using scanning electron microscope and transmission electron microscope as well as parallel plate rheometer. The intercalated clay tactoids are selectively located in the continuous PBT phase due to their nice affinity. A novel morphology evolution of the immiscible blend matrices is observed with increase of clay loadings. Small addition of clay increases the discrete PPS spherulite domain size. With increasing loading levels, the PPS phase transform to the fibrous structure and finally, to the partial laminar structure at the high loading levels, in which shows a characteristic of large‐scaled phase separation. The presence of clay, however, does not impede the coalescence of the PPS phase because the phase size increases with increasing clay loadings. The elasticity and blend ratio of two matrices are proposed as the important roles on the morphological evolution. Moreover, the laminar structure of PPS phase is very sensitive to the steady shear flow and is easy to be broken down to spherulite droplet at the low shear rate. However, high shear level is likely to facilitate the coalescence of those PPS phase and finally to phase inversion, both contributing to increases of the dynamic modulus after steady shear flow. In conclusion, the morphology of the immiscible polymer blend nanocomposites depends strongly on both the clay loadings and shear history. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1265–1279, 2008
Self‐organized micropatterns of high aspect ratio polymer nanofibers by wetting of nanopores
Authors: Kong Jie , Yung Kai‐Leung , Xu Yan , He Lan , Lau K. H. , Chan C. Y.
Published: May 2008

The self‐organized micropatterns of high aspect ratio polymer nanofibers were prepared via a facile nanoporous wetting strategy. Various micropatterns with labyrinth‐like or honeycomb‐like topography can be formed in a controllable manner by adjusting the nanoporous template's nanochannel characteristic (deep‐hole or through‐hole), the size of nanopores, and the wetting time. The honeycomb‐like micropattern shows a little higher hydrophobicity than labyrinth‐like micropattern when the diameters of their nanofibers are similar. The formation of various self‐organized micropatterns is mainly dependant on the dilation stress and interaction between nanofibers during the template's removal and solvent evaporation process. The confining or free conditions of unreleased nanofibers' tips in nanopores determine the topography of the resultant self‐organized micropattern, i.e., labyrinth‐like or honeycomb‐like. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1280–1289, 2008
Advanced electrodes with nanostructured surfaces for electrochemical microsensors
Authors: Klosová K. , Hubálek J.
Published: May 2008

Nanostructures have recently attracted great interest because of their unique properties and potential use in a broad range of technological applications. In the case of electrochemical microsensors, an array of nanostructures can be used to enlarge the surface area of sensing electrodes and it also has a positive impact on the redox reactions on their surfaces. It is assumed that these microsensors will then have higher sensitivity due to the surface modification. One of the easiest ways to modify an electrode surface by nanostructures is to deposit a metal into a thin nanoporous Al2O3 template which is placed on a gold electrode. Metal ions are attracted to the cathode (the gold electrode) during electrodeposition and fill the nanopores in the template. After completing the electrodeposition process, the template is dissolved and the metal nanostructures are obtained. Both nanorods and nanotubes of various wall‐thicknesses can be created by this method. It has been found that the type of the nanostructure depends on specific electroplating conditions (e.g. pH and concentration) and used template (i.e. diameters of the nanopores). Therefore, it is possible to control the type of the nanostructure by adjusting these electroplating parameters and to create either nanorods or nanotubes on purpose. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pt–Co multilayers: Interface effects at the monolayer limit
Authors: Angelakeris M. , Papaioannou E. Th. , Poulopoulos P. , Vlachos A. , Natsiopoulos G. , Wilhelm F. , Rogalev A. , Flevaris N. K.
Published: May 2008

This work focuses on the structural and magnetic features of Pt–Co multilayers prepared by e‐beam evaporation. In order to examine interface and induced magnetism effects, the layer thickness was always kept under 4 monolayers. X‐ray diffraction spectra revealed the multilayer nature of the samples while magnetometry measurements recorded tuneable perpendicular magnetic anisotropy and enhanced magnetization values due to the high degree of Pt‐polarization in a ferromagnetic environment. The experimental technique that allows one to study induced magnetism is the X‐ray magnetic circular dichroism, which provides quantitative information on spin and orbital magnetic moments. Enhanced Pt contribution on the perpendicular anisotropy was evidenced, while the induced (spin, orbital and total) magnetic moments, and the ratio orbital‐to‐spin magnetic moments were derived by application of the sum rules. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interaction between helium and vacancy in plutonium by embedded atom method
Authors: Ao Bingyun , Wang Xiaolin , Hu Wangyu , Yang Jianyu
Published: May 2008

The formation energies of small HenVmclusters (nandmdenote the number of He atoms and vacancy, respectively) in Pu have been calculated with molecular dynamics (MD) simulations using the embedded atom method (EAM) potential, the Morse potential and the Lennard–Jones potential for describing the interactions of Pu–Pu, Pu–He and He–He, respectively. The binding energies of an interstitial He atom, an isolated vacancy and a self‐interstitial Pu atom to a HenVmcluster are also obtained from the calculated formation energies of the clusters. All the binding energies mainly depend on the He‐vacancy ratio (n/m) of clusters rather than the clusters size. With the increase of then/mratio, the binding energies of a He atom and a Pu atom to a HenVmcluster decrease with the ratio, and the binding energy of a vacancy to a HenVmcluster increases. He atoms act as a catalyst for the formation of HenVmclusters. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the composition of Caribbean maritime aerosol particles measured during RICO
Authors: Peter Justin R. , Blyth Alan M. , Brooks Barbara , McQuaid James B. , Lingard Justin J. N. , Smith Mike H.
Published: May 2008

Observations of aerosol‐particle (AP) composition obtained via volatility measurements during the ‘Rain In Cumulus over the Ocean’ (RICO) experiment are presented. The measurements show that sub‐cloud APs with a radius rp ≤ 0.2 µm are composed mainly of ammonium sulphate, while APs with a radius rp ≥ 0.2 µm are composed mainly of sea salt. The AP distribution also contains an indeterminate non‐volatile component (rp ≤ 0.4 µm), which could be either elemental carbon or mineral dust. Copyright © 2008 Royal Meteorological Society
Metabolite identification of small interfering RNA duplex by high‐resolution accurate mass spectrometry
Authors: Zou Yan , Tiller Philip , Chen I‐Wu , Beverly Michael , Hochman Jerome
Published: May 2008

On‐line liquid chromatography/electrospray ionization high‐resolution mass spectrometry (LC/ESI‐HRMS) using an LTQ‐Orbitrap mass spectrometer was employed to investigate the metabolite profiles of a model siRNA duplex designated HBV263. The HBV263 duplex was incubated in rat and human serum and liver microsomes in vitro. The siRNA drug and its metabolites were then extracted using a liquid‐liquid extraction followed by solid‐phase extraction (LLE‐SPE), and analyzed by LC/ESI‐MS. High‐resolution accurate mass data enabled differentiation between two possible metabolite sequences with a monoisotopic molecular mass difference of less than 1 Da. ProMass deconvolution software was used to provide semi‐automated data processing. In vitro serum and liver microsome incubation samples afforded different metabolite patterns: the antisense strand of the duplex was degraded preferentially in rat and human serum, while the sense strand of the duplex was less stable in rat and human liver microsomes. Copyright © 2008 John Wiley & Sons, Ltd.
Characterisation of the peptaibiome of the biocontrol fungus Trichoderma atroviride by liquid chromatography/tandem mass spectrometry
Authors: Stoppacher Norbert , Zeilinger Susanne , Omann Markus , Lassahn Paul‐Gerhard , Roitinger Andreas , Krska Rudolf , Schuhmacher Rainer
Published: May 2008

The present study describes the liquid chromatography/tandem mass spectrometry (LC/MS/MS)‐based screening and characterisation of linear antibiotic α‐aminoisobutyric acid (Aib)‐containing non‐ribosomal peptides (NRP) in culture samples of the filamentous fungus Trichoderma atroviride ATCC 74058. Fungal culture filtrates were enriched by solid‐phase extraction (SPE) and separated by reversed‐phase high‐performance liquid chromatography (HPLC), prior to mass spectrometric (MS) and tandem mass spectrometric (MS/MS) analysis on a triple quadrupole‐linear ion trap tandem mass spectrometer. A workflow consisting of two alternative screening strategies was applied to search for NRP. Various MS full scan and MS/MS measurement modes led to the identification of 16 trichorzianines and diagnostic in‐source fragment ions of another four trichorzianines. Furthermore, we detected 15 novel Aib‐containing peptides with putative molecular weights ranging from 951.7 to 1043.7 g/mol (monoisotopic masses), composed of up to 9 amino acids. While the amino acid sequences of the novel peptaibiotics showed typical microheterogeneity and consisted of the amino acids Leu/Ile, Aib, Ser, Val/Iva, Gly, Ac‐Aib, Tyr and Phe, the mass increments at the C‐termini of the peptides were not assignable to any residues described in the literature. The amino acid sequences were confirmed and structure proposals made for both molecule termini by high‐resolution MS and MS/MS analysis. We propose the group name ‘trichoatrokontins’ for the newly identified peptaibiotics. As no other peptaibiotics were found in the culture samples, the peptaibiome of the investigated strain of T. atroviride consists of at least 20 trichorzianines and 15 trichoatrokontins. Copyright © 2008 John Wiley & Sons, Ltd.
The impact of small and large impoundments on freshwater mussel distribution in the Hawkesbury‐Nepean River, southeastern Australia
Authors: Brainwood Meredith , Burgin Shelley , Byrne Maria
Published: May 2008

The influence of weirs on the distribution of freshwater mussels was investigated in the Hawkesbury‐Nepean River, Australia. Distribution of species and densities of size classes were strongly correlated with catchment level factors (e.g. location around a major impoundment, stream order). At catchment scale, weir height, presence of a fish barrier, fish ladder type and position above or below small weirs did not influence the presence/absence of mussel populations. Lower mussel densities in the upper catchment may therefore reflect inhibition of host fish migration.

Where present, weir height and geomorphic reach type were linked to differences in densities among species. Geomorphic reach‐based differences were reflected by the Hyridella species, but not Velesunio ambiguus. When population structure was described by size class distribution, there were significant differences between densities of small and medium mussels from weirs above, compared to weirs below, a major impoundment, but not for large mussels. Upstream populations may therefore be functionally extinct. Distribution of mussel size classes differed among geomorphic reach types with highest densities for each class found in the least human‐impacted reaches. Small mussels were almost invariably found below the major impoundment, most frequently below weirs.

Distribution patterns were inconsistent across species, suggesting habitat preference. V. ambiguus and Hyridella australis were most abundant in shale reaches, where assemblages were influenced by fish ladder type. Hyridella depressa and H. australis dominated in sandstone gorges and straights with assemblage density related to weir height. In upper catchment sandstone reaches, mussel assemblages comprising predominantly V. ambiguus were influenced by fish ladder type and weir height.

While multiple factors defined localized distribution, large impoundments were linked with reduced population densities. The probable mechanism is the restriction of host fish movement and resulting lack of recruitment. In the Hawkesbury‐Nepean River, smaller weirs also seriously impacted recruitment. Copyright © 2008 John Wiley & Sons, Ltd.
Hydrologic impacts of small‐scale instream diversions for frost and heat protection in the California wine country
Authors: Deitch Matthew J. , Kondolf G. Mathias , Merenlender Adina M.
Published: May 2008

Though many river studies have documented the impacts of large water projects on stream hydrology, few have described the effects of dispersed, small‐scale water projects on streamflow or aquatic ecosystems. We used streamflow and air temperature data collected in the northern California wine country to characterize the influence of small instream diversions on streamflow. On cold spring mornings when air temperatures approached 0°C, flow in streams draining catchments with upstream vineyards receded abruptly, by as much as 95% over hours, corresponding to times when water is used to protect grape buds from freezing; flow rose to near previous levels following periods of water need. Streams with no upstream vineyards showed no such changes in flow. Flow was also depressed in reaches below vineyards on hot summer days, when grape growers commonly use water for heat protection. Our results demonstrate that the changes in flow caused by dispersed small instream diversions may be brief in duration, requiring continuous short‐interval monitoring to adequately describe how such diversions affect the flow regime. Depending on the timing and abundance of such diversions in a drainage network, the changes in streamflow they cause may be an important limiting factor to valued biotic resources throughout the region. Copyright © 2008 John Wiley & Sons, Ltd.
Hydrological and sediment transport dynamics of flushing flows: implications for management in large Mediterranean Rivers
Authors: Batalla Ramon J. , Vericat Damià
Published: May 2008

Flushing flows have been implemented in the lower Ebro River since 2003, with the principle objective of removing excess macrophytes. This paper describes the hydrology and sediment transport of these flushing flows in comparison with natural floods and discusses their effects in terms of riverbed adjustments. During flushing flows suspended sediment, concentration is more constant and double that of natural floods, although discharge is lower. Flashiness, measured as the rate of discharge increase per unit time, is an order of magnitude higher during flushing flows than during natural events. Consequently, flushing flows exhibit higher transport capacity than their natural counterparts despite their considerably lower magnitude and duration. Flushing flows remove up to 95% of macrophytes close to the dam, but their effectiveness reduces with distance downstream. Despite several constraints, flushing flows have significant potential to entrain and transport sediment and careful management of these releases may, therefore, play an important role in enhancing physical habitat in the river and supply sediment to the delta. The River Ebro case study shows that flushing flows are not incompatible with HEP production, and may actually result in a positive trade‐off due to reduced clogging of water intakes. Nevertheless, it remains important to reassess their effectiveness regularly and monitor adverse geomorphic effects such as riverbed degradation. In summary, flushing flows are an important instrument of river management, but one which must be employed as part of a spectrum of approaches to enhance physical habitat conditions. Copyright © 2008 John Wiley & Sons, Ltd.
Meta‐analysis of summary survival curve data
Authors: Arends Lidia R. , Hunink M. G. Myriam , Stijnen Theo
Published: May 2008

The use of standard univariate fixed‐ and random‐effects models in meta‐analysis has become well known in the last 20 years. However, these models are unsuitable for meta‐analysis of clinical trials that present multiple survival estimates (usually illustrated by a survival curve) during a follow‐up period. Therefore, special methods are needed to combine the survival curve data from different trials in a meta‐analysis. For this purpose, only fixed‐effects models have been suggested in the literature. In this paper, we propose a multivariate random‐effects model for joint analysis of survival proportions reported at multiple time points and in different studies, to be combined in a meta‐analysis. The model could be seen as a generalization of the fixed‐effects model of Dear (Biometrics 1994; 50:989–1002). We illustrate the method by using a simulated data example as well as using a clinical data example of meta‐analysis with aggregated survival curve data. All analyses can be carried out with standard general linear MIXED model software. Copyright © 2008 John Wiley & Sons, Ltd.