bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular weight evaluation of depolymerized poly(ethylene terephthalate) using intrinsic viscosity
Authors: Li Kaixiang , Song Xiaofang , Zhang Dong
Published: April 2008

A series of poly(ethylene terephthalate) (PET) depolymerization experiments versus time was proceeded under optimal experimental conditions with microwave radiation, in which the temperature was 220°C, the pressure was 200 psi, the microwave power was 260 W, and the ratio of water to PET was 10 : 1. The relative viscosity of the feedstock PET grain and the residual solid products from depolymerization reaction at six different time, respectively, was measured in the solution of 60/40 (w/w) phenol/1,1,2,2‐tetrachloroethane. Then the approximate intrinsic viscosity was calculated from linear and exponential extrapolation of reduced viscosity. Molecular weights were calculated by Mark‐Houwink's equation, with values of K and α taken from the literatures. The results show that the molecular weights fell dramatically with increasing of reaction time, namely the number average molecular weight from 2.57 × 104 of the feedstock PET to 372 of the remained solid product at 240 min, and the weight average molecular weight of the samples fell from 3.89 × 104 to 408 correspondingly. The intrinsic viscosity decreased greatly with reaction, while the distribution of molecular weight turned to be steady. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Phase inversion process to prepare quasi‐solid‐state electrolyte for the dye‐sensitized solar cells
Authors: Zhang Jing , Han Hongwei , Xu Sheng , Wu Sujuan , Zhou Conghua , Yang Ying , Zhao Xingzhong
Published: April 2008

A quasi‐solid‐state electrolyte for the dye‐sensitized solar cells was prepared following the phase inversion process. The microporous polymer electrolyte based on poly(vinylidene fluoride‐co‐hexafluoropropylene) (P(VDF‐HFP)) hybrid with different amount of TiO2 nanoparticles were prepared. The surface morphologies, the differential scanning calorimetry, and the ionic conductivity of the microporous polymer electrolyte were tested and analyzed. The results indicated that the microporous polymer electrolyte with TiO2 nanoparticles modification exhibited better ionic conductivity compared with the original P(VDF‐HFP) polymer electrolyte. The optimal ionic conductivity of 0.8 mS cm−1 is obtained with the 30 wt % TiO2 nanoparticles modification. When assembled with the 30 wt % TiO2 nanoparticles modified quasi‐solid‐state electrolyte, the dye‐sensitized TiO2 nanocrystalline solar cell exhibited the light to electricity conversion efficiency of 2.465% at light intensity of 42.6 mW cm−2, much better than the performance of original P(VDF‐HFP) microporous polymer electrolyte DSSC. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Morphology and mechanical properties of natural rubber and styrene‐grafted natural rubber latex compounds
Authors: Arayapranee Wanvimon , Rempel Garry L.
Published: April 2008

The mechanical properties of natural rubber latex (NRL) modified with styrene‐grafted natural rubber (styrene‐GNR) latex were investigated. Styrene‐GNR was first synthesized via emulsion copolymerization using cumene hydroperoxide/tetraethylene pentamine as an initiator. The styrene‐GNR latex produced was mixed with NRL with various latex compounding contents and then prevulcanization was carried out. The mechanical properties and heat, weathering, and ozone resistance of the natural rubber (NR) and styrene‐GNR latex compounds were investigated as a function of the grafted NR content. The results indicated that the tensile and tear strength were decreased, whereas Young's modulus and hardness were increased at high content of styrene‐GNR. Addition of styrene‐GNR improved the resistance of the compounds to heat and weathering ageing. The ozone resistance of the compound containing styrene‐GNR is superior to that of the NR‐rich compound. The results indicated that NR/styrene‐GNR latex compounds maintained good antiageing properties required for outdoor applications. The tensile fracture surface examined by scanning electron microscopy confirmed a shift from ductility failure to brittle with an increase of the styrene‐GNR content in the compounds. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Statistical analysis of personal radiofrequency electromagnetic field measurements with nondetects
Authors: Röösli Martin , Frei Patrizia , Mohler Evelyn , Braun‐Fahrländer Charlotte , Bürgi Alfred , Fröhlich Jürg , Neubauer Georg , Theis Gaston , Egger Matthias
Published: April 2008

Exposimeters are increasingly applied in bioelectromagnetic research to determine personal radiofrequency electromagnetic field (RF‐EMF) exposure. The main advantages of exposimeter measurements are their convenient handling for study participants and the large amount of personal exposure data, which can be obtained for several RF‐EMF sources. However, the large proportion of measurements below the detection limit is a challenge for data analysis. With the robust ROS (regression on order statistics) method, summary statistics can be calculated by fitting an assumed distribution to the observed data. We used a preliminary sample of 109 weekly exposimeter measurements from the QUALIFEX study to compare summary statistics computed by robust ROS with a naïve approach, where values below the detection limit were replaced by the value of the detection limit. For the total RF‐EMF exposure, differences between the naïve approach and the robust ROS were moderate for the 90th percentile and the arithmetic mean. However, exposure contributions from minor RF‐EMF sources were considerably overestimated with the naïve approach. This results in an underestimation of the exposure range in the population, which may bias the evaluation of potential exposure‐response associations. We conclude from our analyses that summary statistics of exposimeter data calculated by robust ROS are more reliable and more informative than estimates based on a naïve approach. Nevertheless, estimates of source‐specific medians or even lower percentiles depend on the assumed data distribution and should be considered with caution. Bioelectromagnetics. Bioelectromagnetics 29:471–478, 2008. © 2008 Wiley‐Liss, Inc.
Cytotoxic Triterpenoids from the Root Bark of Helicteres angustifolia
Authors: Pan Min‐Hsiung , Chen Chiu‐Ming , Lee Shwu‐Woan , Chen Zong‐Tsi
Published: April 2008

Three new triterpenoids, 3β‐acetoxy‐27‐[(E)‐cinnamoyloxy]lup‐20(29)‐en‐28‐oic acid methyl ester (1), 3β‐acetoxy‐27‐[(4‐hydroxybenzoyl)oxy]lup‐20(29)‐en‐28‐oic acid (2), and 3β‐acetoxy‐27‐[(4‐hydroxybenzoyl)oxy]olean‐12‐en‐28‐oic acid methyl ester (3), together with nine known triterpenoids, 4–12, were isolated from the root bark of Helicteres angustifolia. The structures of these compounds were established on the basis of spectroscopic methods including 2D‐NMR experiments. All twelve compounds were tested for their cytotoxic activities against human colorectal cancer (COLO 205), human hepatoma (Hep G2), and human gastric cancer (AGS) cell lines in vitro. Among them, compounds 2, 3, 3β‐O‐[(E)‐coumaroyl]betulinic acid (6), and pyracrenic acid (7) showed significant cytotoxic activities against human cancer cells COLO 205 and AGS.
Anthracene Carboxyimides and Their Dimers
Authors: Langhals Heinz , Schönmann Gertrud , Polborn Kurt
Published: April 2008

Soluble anthracenedicarboxyimides have been prepared and undergo a photodimerisation of the anthracene skeleton, which is important for their application as antitumour agents, such as azonafides. Reaction under strongly alkaline conditions causes CC coupling to form soluble dimeric fluorescent dyes with bathochromic absorption and fluorescence in the NIR region. These dyes are of special interest because of their absorption at longer wavelengths.
Potential‐Energy and Free‐Energy Surfaces of Glycyl‐Phenylalanyl‐Alanine (GFA) Tripeptide: Experiment and Theory
Authors: Valdes Haydee , Spiwok Vojtech , Rezac Jan , Reha David , Abo‐Riziq Ali G. , de Vries Mattanjah S. , Hobza Pavel
Published: April 2008

The free‐energy surface (FES) of glycyl‐phenylalanyl‐alanine (GFA) tripeptide was explored by molecular dynamics (MD) simulations in combination with high‐level correlated ab initio quantum chemical calculations and metadynamics. Both the MD and metadynamics employed the tight‐binding DFT‐D method instead of the AMBER force field, which yielded inaccurate results. We classified the minima localised in the FESs as follows: a) the backbone‐conformational arrangement; and b) the existence of a COOH⋅⋅⋅OC intramolecular H‐bond (families CO2Hfree and CO2Hbonded). Comparison with experimental results showed that the most stable minima in the FES correspond to the experimentally observed structures. Remarkably, however, we did not observe experimentally the CO2Hbonded family (also predicted by metadynamics), although its stability is comparable to that of the CO2Hfree structures. This fact was explained by the former's short excited‐state lifetime. We also carried out ab initio calculations using DFT‐D and the M06‐2X functional. The importance of the dispersion energy in stabilising peptide conformers is well reflected by our pioneer analysis using the DFT‐SAPT method to explore the nature of the backbone/side‐chain interactions.
ChemInform Abstract: Asymmetric Nitroaldol Reaction Catalyzed by a Chromium(III)—Salen System.
Authors: Kowalczyk Rafal , Sidorowicz Lukasz , Skarzewski Jacek
Published: April 2008

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Preparation of Novel Azabicyclic Amines and α7 Nicotinic Acetylcholine Receptor Activity of Derived Aryl Amides.
Authors: Walker Daniel P. , Acker Brad A. , Jacobsen E. Jon , Wishka Donn G.
Published: April 2008

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Marine Diterpenoids with a Briarane Skeleton from the Okinawan Soft Coral Pachyclavularia violacea
Authors: Ito Hisanaka , Iwasaki Junya , Sato Yuki , Aoyagi Miwako , Iguchi Kazuo , Yamori Takao
Published: April 2008

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Chlorinated Briarane‐Type Diterpenoids from the Gorgonian Coral Ellisella robusta (Ellisellidae).
Authors: Sung Ping‐Jyun , Chiang Michael Y. , Tsai Wei‐Tse , Su Jui‐Hsin , Su Yu‐Mine , Wu Yang‐Chang
Published: April 2008

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: The Catalytic Asymmetric Strecker Reaction: Ketimines Continue to Join the Fold
Authors: Connon Stephen J.
Published: April 2008

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
The motor activity of mammalian axonemal dynein studied in situ on doublet microtubules
Authors: Lorch David P. , Lindemann Charles B. , Hunt Alan J.
Published: April 2008

Flagellar dynein generates forces that produce relative shearing between doublet microtubules in the axoneme; this drives propagated bending of flagella and cilia. To better understand dynein's role in coordinated flagellar and ciliary motion, we have developed an in situ assay in which polymerized single microtubules glide along doublet microtubules extruded from disintegrated bovine sperm flagella at a pH of 7.8. The exposed, active dynein remain attached to their respective doublet microtubules, allowing gliding of individual microtubules to be observed in an environment that allows direct control of chemical conditions. In the presence of ATP, translocation of microtubules by dynein exhibits Michaelis‐Menten type kinetics, with Vmax = 4.7 ± 0.2 μm/s and Km = 124 ± 11 μM. The character of microtubule translocation is variable, including smooth gliding, stuttered motility, oscillations, buckling, complete dissociation from the doublet microtubule, and occasionally movements reversed from the physiologic direction. The gliding velocity is independent of the number of dynein motors present along the doublet microtubule, and shows no indication of increased activity due to ADP regulation. These results reveal fundamental properties underlying cooperative dynein activity in flagella, differences between mammalian and non‐mammalian flagellar dynein, and establish the use of natural tracks of dynein arranged in situ on the doublet microtubules of bovine sperm as a system to explore the mechanics of the dynein‐microtubule interactions in mammalian flagella. Cell Motil. Cytoskeleton 2008. © 2008 Wiley‐Liss, Inc.
Pigmented and nonpigmented ocelli in the brain vesicle of the ascidian larva
Authors: Horie Takeo , Sakurai Daisuke , Ohtsuki Hisashi , Terakita Akihisa , Shichida Yoshinori , Usukura Jiro , Kusakabe Takehiro , Tsuda Motoyuki
Published: April 2008

The vertebrate‐type opsin, Ci‐opsin1, is localized in the outer segments of the photoreceptor cells of larvae of the ascidian Ciona intestinalis. The absorption spectrum of the photopigment reconstituted from Ci‐opsin1 and 11‐cis‐retinal suggested that the photopigment is responsible for photic behavior of the larvae. The structure and function of Ci‐opsin1‐positive photoreceptor cells were examined by immunohistochemistry, confocal microscopy, electron microscopy, laser ablation, and behavioral analysis. Ciona larvae have three morphologically distinct groups of photoreceptor cells in the brain vesicle. Group I and group II photoreceptor cells are associated with the ocellus pigment cell on the right side of the brain vesicle. The outer segments of the group I photoreceptor cells are regularly arranged inside the small cavity encircled by the cup‐shaped pigment cell. The outer segments of the group II photoreceptor cells are located outside the pigment cavity and exposed to the lumen of the brain vesicle. The outer segments of the group III photoreceptor cells are located near the otolith on the left ventral side of the brain vesicle. Thus, the brain vesicle of the ascidian larva has two ocelli: a ‘conventional’ pigmented ocellus containing the group I and group II photoreceptor cells and a novel nonpigmented ocellus solely consisting of the group III photoreceptor cells. Laser ablation experiments suggest that the pigmented ocellus is responsible for the photic swimming behavior. The nonpigmented ocellus might relate to later developmental or physiological events, such as metamorphosis, because Ci‐opsin1 immunoreactivity appears in the late larval stage and becomes intense just before the onset of metamorphosis. J. Comp. Neurol. 509:88–102, 2008. © 2008 Wiley‐Liss, Inc.
Thermodynamic Aspects of Diamond/β‐SiC Composite Films
Authors: Srikanth Vadali V. S. S. , Trindade Vicente Braz , Staedler Thorsten , Jiang Xin
Published: April 2008

A thermodynamic equilibrium analysis involving H2CH4Si(CH3)4 (tetramethylsilane, TMS) gas mixtures is made to understand the evolution of major gas‐phase species and to predict the solid‐phase co‐deposition of diamond and β‐SiC phases. The equilibrium compositions are analyzed at the practical deposition conditions of nanocrystalline diamond/β‐SiC composite films. The influence of various predominant species on the equilibrium compositions is investigated.
Vanadium(I) Chloride and Lithium Vanadium(I) Dihydride as Epimetallating Reagents for Unsaturated Organic Substrates: Constitution and Mode of Reaction
Authors: Eisch John J. , Fregene Paul O. , Doetschman David C.
Published: April 2008

Subvalent vanadium(I) salts, of empirical formulas, VCl, vanadium(I) chloride and LiVH2, lithium vanadium(I) dihydride, can be conveniently prepared in THF solution, starting at –78 °C, by treating either VCl3 or VCl4 with an appropriate number of equivalents of nBuLi. As judged by the stability of solutions or solid samples of LiVH2, the preparation of LiVH2 from VCl4 is the preferred method. Individual physical characterization of solid samples of VCl or of LiVH2, admixed with their LiCl by‐product, was carried out after removal of all volatiles in vacuo and by the following measurements: 1) gasometric protolysis with glacial acetic acid and measurement of the H2 evolved in the oxidation of VI to VII; 2) infrared spectroscopic search for V–H bands; and 3) examination for unpaired electrons by EPR activity. Such measurements applied to VCl lend strong support for a VI oxidation state but only probable evidence for paramagnetism and for the association of VCl units. Similar measurements applied to LiVH2 give unambiguous gasometric and IR evidence favoring the LiVH2 stoichiometry and the biradical nature of the VH2 anion with a linear array of H–V–H atoms. Chemical characterization of both VCl and LiVH2 toward individual organic substrates, such as olefins, ketones, epoxides and organic halides, yielded convincing evidence that organic radical mechanisms are involved, both for the proven biradical, LiVH2, as well as for the diamagnetic VCl. Finally, the question of why LiVH2 prepared from VCl4 is more stable than the LiVH2 obtained from VCl3 is addressed in terms of the actual coordination sphere of the VH2 anion in THF solution and in the solid state. Preliminary studies comparing the reactivities of LiVH2 and LiCrH2 toward organic substrates indicate that LiVH2 is the distinctly more moderate and usefully selective reductant. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
2‐Azido‐2‐deoxycellulose: Synthesis and 1,3‐Dipolar Cycloaddition
Authors: Zhang Fuyi , Bernet Bruno , Bonnet Véronique , Dangles Olivier , Sarabia Francisco , Vasella Andrea
Published: April 2008

Chitosan (1) was prepared by basic hydrolysis of chitin of an average molecular weight of 70000 Da, 1H‐NMR spectra indicating almost complete deacetylation. N‐Phthaloylation of 1 yielded the known N‐phthaloylchitosan (2), which was tritylated to provide 3a and methoxytritylated to 3b. Dephthaloylation of 3a with NH2NH2⋅H2O gave the 6‐O‐tritylated chitosan 4a. Similarly, 3b gave the 6‐O‐methoxytritylated 4b. CuSO4‐Catalyzed diazo transfer to 4a yielded 95% of the azide 5a, and uncatalyzed diazo transfer to 4b gave 82% of azide 5b. Further treatment of 5a with CuSO4 produced 2‐azido‐2‐deoxycellulose (7). Demethoxytritylation of 5b in HCOOH gave 2‐azido‐2‐deoxy‐3,6‐di‐O‐formylcellulose (6), which was deformylated to 7. The 1,3‐dipolar cycloaddition of 7 to a range of phenyl‐, (phenyl)alkyl‐, and alkyl‐monosubstituted alkynes in DMSO in the presence of CuI gave the 1,2,3‐triazoles 8–15 in high yields.
Impact of ecologically relevant heat shocks on Hsp developmental function in the vetigastropod Haliotis asinina
Authors: Gunter Helen M. , Degnan Bernard M.
Published: April 2008

Heat shock proteins (Hsps) are essential for cellular maintenance, normal differentiation and morphogenesis, and protection against a range of environmental stresses. It is unknown which of these roles takes precedence when they are required simultaneously. Here we examined the impact of thermal stress on the complex developmental expression patterns of HasHsp70 and HasHsp90A in the vetigastropod Haliotis asinina. We find that near‐lethal heat shocks do not alter the spatial demarcation of Hsp expression despite such treatments impacting on the external character of the embryos. Using a suite of molecular markers that are both coexpressed with the Hsps (i.e. in ventrolateral ectoderm and prototroch) and expressed in tissues that have lower (basal) Hsp expression (e.g. serotonergic nervous system and shell gland), we determined that Hsp‐expressing tissues do not incur markedly less thermal damage than adjacent tissues. To explore the relationship of Hsp expression with sensitivity of specific cell territories to heat shock, we focused on the formation of the prototroch, a tissue where HasHsp70 and HasHsp90A are coexpressed. By heat shocking at specific developmental stages, we determined that the most sensitive period of prototroch development is during its early specification and differentiation, which overlaps with the time the Hsps are expressed at their highest levels in these cells. This correlation is consistent with heat shock impairing the function of Hsps in regions of the H. asinina embryo undergoing morphogenesis. J. Exp. Zool. (Mol. Dev. Evol.) 310B:450–464, 2008. © 2008 Wiley‐Liss, Inc.
Independent component analysis of dynamic contrast‐enhanced magnetic resonance images of breast carcinoma: A feasibility study
Authors: Koh Tong San , Thng Choon Hua , Ho Juliana T.S. , Tan Puay Hoon , Rumpel Helmut , Khoo James B.K.
Published: April 2008

Purpose

To study the possibility of using independent component analysis (ICA) to identify breast lesions as separate hemodynamic sources on dynamic contrast‐enhanced (DCE) MR images, as depicted by the passage of contrast medium.

Materials and Methods

Six patients who were histopathologically confirmed with breast carcinoma underwent DCE MRI with 5 precontrast and 60 postcontrast scans at a time‐resolution of 8 s. A spatial ICA algorithm was applied on the DCE MRI data set to extract spatial component maps corresponding to source locations with different signal time–intensity patterns. To verify the present hypothesis of the ability of ICA to reveal tumor voxels as a separate hemodynamic phase, tumor margins were outlined by an experienced radiologist who was blinded from the ICA results, and the manual outlines were compared with the ICA maps.

Results

Consistently for each of the six patient study cases, it was found that ICA yields a tumor component map associated with typical tumor enhancement patterns of rapid enhancement with washout or plateau. Tumor outlines manually drawn by the radiologist were in good agreement with the tumor locations depicted in the tumor component maps.

Conclusion

ICA may provide an objective method for identifying the outlines of enhancing breast tumors on DCE MR images and to automatically extract the tumor signal intensity–time curve for subsequent tracer kinetics analysis. J. Magn. Reson. Imaging 2008. © 2008 Wiley‐Liss, Inc.
Characterization of the pH‐dependent dissociation of a multimeric metalloprotein Streptomyces rubiginosus xylose isomerase by ESI FT‐ICR mass spectrometry
Authors: Jänis Janne , Pasanen Salla , Rouvinen Juha , Vainiotalo Pirjo
Published: April 2008

We report an analysis of the pH‐dependent dissociation of a multimeric metalloprotein, xylose isomerase from Streptomyces rubiginosus (XI), by electrospray ionization (ESI) Fourier transform ion cyclotron resonance (FT‐ICR) mass spectrometry. Xylose isomerases are industrially significant enzymes that catalyze interconversion of aldose and ketose sugars. XI is biologically active as a ∼173‐kDa tetrameric complex, comprised of four identical ∼43‐kDa subunits and eight metal cations, unequivocally identified as the Mg2+ cations in this work. ESI FT‐ICR mass spectra of XI measured in the pH range of 3.0–6.9 indicated that the dissociation of the intact holo‐tetramer is initiated by the loss of all eight Mg2+ cations at pH ≤5.0, followed by step‐by‐step dissociation of the remaining apo‐tetramer to trimers, dimers and monomers. In addition, a ∼346‐kDa protein octamer was detected at pH 6.9. Copyright © 2008 John Wiley & Sons, Ltd.
Evaluation of a new matrix‐free laser desorption/ionization method through statistic studies: comparison of the DIAMS (desorption/ionization on self‐assembled monolayer surface) method with the MALDI and TGFA‐LDI techniques
Authors: Bounichou Matthieu , Sanguinet Lionel , Elouarzaki Kamal , Alévêque Olivier , Dias Marylène , Levillain Eric , Rondeau David
Published: April 2008

This work demonstrates that the desorption/ionization on self‐assembled monolayer surface (DIAMS) mass spectrometry, a recent matrix‐free laser desorption/ionization (LDI) method based on an organic target plate, is as statistically repeatable and reproducible as matrix assisted laser desorption ionization (MALDI) and thin gold film‐assisted laser desorption/ionization (TGFA‐LDI) mass spectrometries. On lipophilic DIAMS of target plates with a mixture of glycerides, repeatability/reproducibility has been estimated at 15 and 30% and the relative detection limit has been evaluated at 0.3 and 3 pmol, with and without NaI respectively. Salicylic acid and its d6‐isomer analysis confirm the applicability of the DIAMS method in the detection of compounds of low molecular weight. Copyright © 2008 John Wiley & Sons, Ltd.
Color stability of frozen whole tilapia exposed to pre‐mortem treatment with carbon monoxide
Authors: Mantilla David , Kristinsson Hordur G , Balaban Murat O , Otwell W Steven , Chapman Frank A , Raghavan Sivakumar
Published: April 2008

BACKGROUND: Color of muscle foods plays a major role in consumer perception of meat quality. Carbon monoxide (CO) has been successfully used for improving color of packaged meat and fish products. In this study, we wanted to investigate pre‐mortem treatment of live tilapia using 100% CO for its ability to improve the color of frozen whole tilapia. We compared untreated and CO‐treated whole, gutted tilapia, frozen for 2 and 4 months at − 20 °C. Frozen tilapia samples were thawed overnight at 4 °C, filleted and analyzed for their color, heme peak wavelength and CO concentration.

RESULTS: Euthanasia using CO significantly increased redness (a* value) and lightness (L* value) of tilapia white and red muscle. Frozen storage significantly (P < 0.05) decreased redness of both CO‐treated and untreated tilapia. However, even after 4 months of frozen storage, a*‐value of CO‐treated tilapia was similar to fresh untreated tilapia fillets. Heme peak wavelengths of CO‐euthanized tilapia were higher than in untreated tilapia and there was no significant (P > 0.05) decrease in heme peak wavelengths of CO‐treated tilapia white and red muscle during frozen storage. The CO content of frozen euthanized tilapia fillets was significantly (P > 0.05) higher than in untreated fillets. In general, red muscle tissue of euthanized tilapia had a higher concentration of CO than white muscle.

CONCLUSION: Color stability of tilapia fillets was significantly improved by pre‐mortem CO treatment. The color of CO‐treated fillets was retained during frozen storage compared to untreated fillets. Hence, pre‐mortem CO treatment could be used as a new method for improving color of tilapia. Copyright © 2008 Society of Chemical Industry
High‐performance liquid chromatography procedure for the determination of flavor enhancers in consumer chocolate products and artificial flavors
Authors: Risner Charles H , Kiser Melissa J
Published: April 2008

BACKGROUND: A number of individual high‐performance liquid chromatography (HPLC) procedures exist for the analysis of maltol, theobromine, ethyl maltol, catechin, vanillic acid, caffeine, vanillin, epicatechin, and ethyl vanillin. A single procedure utilizing simple sample preparation and less sophisticated equipment would be advantageous for the analysis of different sample types containing these compounds.

RESULTS: An HPLC procedure has been developed using water as the extract for consumer products and artificial flavors. A methanol–water gradient was used to elute the compounds of interest using a reverse‐phase column. Absorbance detection using a wavelength of 273 nm was used to monitor the eluent. Recoveries for these compounds ranged from 88% to 104%.

CONCLUSIONS: Results obtained for theobromine, catechin, caffeine, and epicatechin in Standard Reference Material 2380 Baking Chocolate compare well with those found in its certificate of analysis verifying that the procedure is valid. Vanillic acid and ethyl vanillic acid were found as oxidation products of vanillin and ethyl vanillin in both standards and some consumer products. Copyright © 2008 Society of Chemical Industry
Protective effect of polyphenol‐rich extract prepared from Malaysian cocoa (Theobroma cacao) on glucose levels and lipid profiles in streptozotocin‐induced diabetic rats
Authors: Ruzaidi Azli Mohd Mokhtar , Abbe Maleyki Mhd Jalil , Amin Ismail , Nawalyah Abdul Ghani , Muhajir Hamid
Published: April 2008

BACKGROUND: Cocoa beans are used for preparing cocoa liquor and cocoa powder, which are the main ingredients of cocoa‐based products. Previous studies have reported the health benefits of cocoa polyphenols in reducing the risk of cardiovascular diseases. However, there is no report on the efficacy of cocoa polyphenols on diabetes mellitus. Therefore this study was designed to evaluate the protective effect of cocoa polyphenol‐rich extract (CE) on glucose levels and lipid profiles in streptozotocin (STZ)‐induced diabetic rats. Male Sprague‐Dawley rats were divided into diabetic control, diabetic CE and diabetic glibenclamide groups.

RESULTS: Three different dosages of CE (10, 20 and 30 mg per 100 g body weight) were administered orally once a day for 1 week before STZ injection and for 3 weeks thereafter. The results showed that CE could normalise the body weight loss caused by STZ. In the 20 mg CE‐pretreated group there was a 143% increase in plasma glucose levels, compared with a 226% increase in diabetic control rats. CE could also normalise total cholesterol, triglycerides and high‐density lipoprotein cholesterol at the end of the experiment compared with the baseline.

CONCLUSION: The present study suggests that pretreatment with CE from roasted cocoa beans could prevent the development of diabetes induced by STZ injection in rats. Copyright © 2008 Society of Chemical Industry
Proteomics in gram‐negative bacterial outer membrane vesicles
Authors: Lee Eun‐Young , Choi Dong‐Sic , Kim Kwang‐Pyo , Gho Yong Song
Published: April 2008

Gram‐negative bacteria constitutively secrete outer membrane vesicles (OMVs) into the extracellular milieu. Recent research in this area has revealed that OMVs may act as intercellular communicasomes in polyspecies communities by enhancing bacterial survival and pathogenesis in hosts. However, the mechanisms of vesicle formation and the pathophysiological roles of OMVs have not been clearly defined. While it is obvious that mass spectrometry‐based proteomics offers great opportunities for improving our knowledge of bacterial OMVs, limited proteomic data are available for OMVs. The present review aims to give an overview of the previous biochemical, biological, and proteomic studies in the emerging field of bacterial OMVs, and to give future directions for high‐throughput and comparative proteomic studies of OMVs that originate from diverse Gram‐negative bacteria under various environmental conditions. This article will hopefully stimulate further efforts to construct a comprehensive proteome database of bacterial OMVs that will help us not only to elucidate the biogenesis and functions of OMVs but also to develop diagnostic tools, vaccines, and antibiotics effective against pathogenic bacteria. © 2008 Wiley Periodicals, Inc., Mass Spec Rev 27: 535–555, 2008
Generalized MRI reconstruction including elastic physiological motion and coil sensitivity encoding
Authors: Odille Freddy , Cîndea Nicolae , Mandry Damien , Pasquier Cédric , Vuissoz Pierre‐André , Felblinger Jacques
Published: April 2008

This article describes a general framework for multiple coil MRI reconstruction in the presence of elastic physiological motion. On the assumption that motion is known or can be predicted, it is shown that the reconstruction problem is equivalent to solving an integral equation—known in the literature as a Fredholm equation of the first kind—with a generalized kernel comprising Fourier and coil sensitivity encoding, modified by physiological motion information. Numerical solutions are found using an iterative linear system solver. The different steps in the numerical resolution are discussed, in particular it is shown how over‐determination can be used to improve the conditioning of the generalized encoding operator. Practical implementation requires prior knowledge of displacement fields, so a model of patient motion is described which allows elastic displacements to be predicted from various input signals (e.g., respiratory belts, ECG, navigator echoes), after a free‐breathing calibration scan. Practical implementation was demonstrated with a moving phantom setup and in two free‐breathing healthy subjects, with images from the thoracic‐abdominal region. Results show that the method effectively suppresses the motion blurring/ghosting artifacts, and that scan repetitions can be used as a source of over‐determination to improve the reconstruction. Magn Reson Med, 2008. © 2008 Wiley‐Liss, Inc.
Interleukin‐1 exacerbates focal cerebral ischemia and reduces ischemic brain temperature in the rat
Authors: Parry‐Jones Adrian R. , Liimatainen Timo , Kauppinen Risto A. , Gröhn Olli H.J. , Rothwell Nancy J.
Published: April 2008

The proinflammatory cytokine interleukin‐1 (IL‐1) is a key mediator of inflammation in cerebral ischemia, but its precise mechanisms of action remain elusive. Temperature is critical to outcome in brain injury and given the importance of IL‐1 in pyrogenesis this has clear mechanistic implications. IL‐1 exacerbates ischemia independently of core (rectal) temperature. However, it is temperature in the ischemic brain that influences outcome and rectal temperature is likely to be a poor surrogate marker. This study tested the hypothesis that IL‐1 exacerbates cerebral ischemia by increasing ischemic brain temperature. Wistar rats undergoing transient middle cerebral artery occlusion received either 4 μg/kg IL‐1 (n = 9) or vehicle (n = 10) intraperitoneally. NMR‐generated maps of brain temperature, tissue perfusion, and the trace of the diffusion tensor were collected during occlusion, early reperfusion, and at 24 hr. IL‐1 significantly increased ischemic damage at 24 hr by 35% but rectal temperature did not vary significantly between groups. However, ischemic brain was 1.7°C cooler on reperfusion in IL‐1‐treated animals (vs. vehicle) and a corresponding reduction in cerebral blood flow was identified in the ischemic striatum. Contrary to the stated hypothesis, IL‐1 reduced ischemic brain temperature during reperfusion and this may be due to a reduction in tissue perfusion. Magn Reson Med, 2008. © 2008 Wiley‐Liss, Inc.
Quantitative magnetic resonance spectroscopy in the entire human cervical spinal cord and beyond at 3T
Authors: Henning Anke , Schär Michael , Kollias Spyros S. , Boesiger Peter , Dydak Ulrike
Published: April 2008

Quantitative magnetic resonance spectroscopy (MRS) amends differential diagnostics of neurological pathology. However, due to technical challenges, it has rarely been applied to the spinal cord and has mainly been restricted to the very upper part of the cervical spine. In this work, an improved acquisition protocol is proposed that takes technical problems as strong magnetic field inhomogeneities, pulsatile flow of the cerebrospinal fluid (CSF), and small voxel size into account. For that purpose, inner‐volume saturated point‐resolved spectroscopy sequence (PRESS) localization, ECG triggering, and localized higher‐order shimming and F0 determination, based on high‐resolution cardiac‐triggered static magnetic field B0 mapping, are combined. For inner‐volume saturation a highly selective T1‐ and B1‐insensitive outer‐volume suppression (OVS) sequence based on broadband RF pulses with polynomial‐phase response (PPR) is used. Validation is performed in healthy volunteers and patients with multiple sclerosis and intramedullary tumors. The applicability of spinal cord MRS is extended to the entire cervical spine. Spectral quality and its consistency are improved. In addition, high quality MRS patient data from a lesion that occluded the spinal canal in the thoracic spinal cord could be acquired. A quantitative analysis of patient spectra and spectra from healthy volunteers at different positions along the spinal cord underlines the diagnostic value of spinal cord MRS. Magn Reson Med 59:1250–1258, 2008. © 2008 Wiley‐Liss, Inc.
High‐resolution NMR imaging of paramagnetic liposomes targeted to a functionalized surface
Authors: Huinink H.P. , Sanders H.M.H.F. , Erich S.J.F. , Nicolay K. , Strijkers G.J. , Merkx M. , Adan O.C.G
Published: April 2008

A major application of molecular MR imaging is receptor mapping of cells lining blood vessels with targeted contrast agents. Since these agents accumulate at interfaces, knowledge of their influence on the relaxation process in this specific configuration is a prerequisite for understanding their working principle. A methodology is presented to study the influence of targeted contrast agents on surface relaxation in vitro. Paramagnetic liposomes attached to a functionalized surface were studied with high‐resolution NMR imaging. The surface was prepared by covering a solid substrate with a layer of collagen. Paramagnetic liposomes were targeted to this surface by functionalizing the liposomes with collagen adhesion protein CNA‐35. With a saturation‐recovery sequence, 1D magnetization profiles with a resolution of 5 μm were measured in water in contact with the surface. Analytical predictions, obtained with the Bloch–Torrey equation, perfectly agreed with the experimental data. Therefore, the magnitude of the surface relaxation rate could be determined from the measurements without any assumption. By using the relaxivity of liposome solutions the surface coverage by liposomes could be estimated. With the presented methodology the behavior of Gd‐based targeted contrast agents at biological interfaces can be studied in vitro. Their influence on relaxation processes can be characterized and quantified. Magn Reson Med, 2008. © 2008 Wiley‐Liss, Inc.
Fast prospective registration of in vivo MR images of trabecular bone microstructure in longitudinal studies
Authors: Rajapakse Chamith S. , Magland Jeremy F. , Wehrli Felix W.
Published: April 2008

In micro‐MRI studies of trabecular bone designed to evaluate structural changes in response to intervention, follow‐up scan volumes do not typically align exactly with the baseline scan volumes due to the orientation and placement of the anatomic location, here the distal tibia, relative to the scanner coordinates. Failure of accurate registration of the follow‐up to the baseline images introduces errors due to the inherent anisotropy in the trabecular network and anisotropic voxel size. In this work it is shown that these limitations can be overcome by incorporating on‐line prospective registration into the data acquisition protocol. The technique is based on a short 3D localizer scan of 1 mm isotropic resolution prior to acquiring the high‐resolution images. During the follow‐up exam, localizer images are registered on‐site with an algorithm relying on a fast Fourier transform for maximizing the correlation between baseline and follow‐up localizers. Transformation parameters obtained in this manner are then fed into the scanner software so that the imaging slab for the high‐resolution follow‐up images is automatically positioned consistent with that of the baseline scan. Based on phantom and human subject studies it is shown that prospective registration yields very close matching between baseline and follow‐up imaging volumes. Magn Reson Med, 2008. © 2008 Wiley‐Liss, Inc.
Assessment of lipids in skeletal muscle by high‐resolution spectroscopic imaging using fat as the internal standard: Comparison with water referenced spectroscopy
Authors: Weis J. , Johansson L. , Ortiz‐Nieto F. , Ahlström H.
Published: April 2008

The main purpose of the study was to compare proton (1H) single‐voxel MR spectroscopy (MRS) with high‐spatial‐resolution spectroscopic imaging (MRSI) to determine the lipid content in human skeletal muscle. Unsuppressed water line was used as a concentration reference in the processing of single‐voxel spectra. The spectrum from yellow bone marrow with a 100% fat content and probe with the vegetable oil served as internal and external reference for high‐spatial‐resolution MRSI, respectively. Very good correlation was found between lipid concentrations measured by water referenced single‐voxel MRS and high‐spatial‐resolution MRSI with yellow bone marrow as the internal standard. Excellent correlation was found between total lipid concentrations estimated by high‐spatial‐resolution MRSI with vegetable oil as the external fat standard and yellow bone marrow as the internal reference. From comparison of single‐voxel MRS and MRSI approaches, it follows that relaxation correction of the reference water and methylene fat line is inevitable in processing the standard single‐voxel spectra. The high‐resolution MRSI approach is recommended to avoid the problem of relaxation corrections and enables using vegetable oil as the external fat standard. Magn Reson Med 59:1259–1265, 2008. © 2008 Wiley‐Liss, Inc.
Performance of a 200‐MHz cryogenic RF probe designed for MRI and MRS of the murine brain
Authors: Ratering David , Baltes Christof , Nordmeyer‐Massner Jurek , Marek Daniel , Rudin Markus
Published: April 2008

A cryogenic 200‐MHz RF transmit/receive probe (CryoProbe) made of copper and designed for murine brain studies is described. The probe operates at 30K and its performance was compared to a home‐made surface coil of equal dimensions and a mouse head volume resonator, both operating at room temperature (RT). Since for small volumes of tissue interrogated (<5 mL) sample noise and thermal noise of the receiver are of comparable magnitude, considerable noise reduction can be achieved by cooling of the receiver system, e.g., using cold helium gas. The effect of temperature lowering on the signal‐to‐noise ratio (SNR) was assessed in phantom and in vivo murine brain studies using conventional MRI sequences (spin and gradient echo) and single voxel MR spectroscopy. Consistent sensitivity increases were observed for the CryoProbe. SNR increases by a factor ≥2 for the phantom experiments and by factors of 1.8 to 1.9 for in vivo experiments when compared to the RT surface coil for both MRI and MRS experiments. These results are in good agreement with estimated SNR gains for a circular surface coil probe cooled to 30K. The use of a cryogenic probe represents an economically attractive option to enhance the sensitivity in small animal MRI/MRS. Magn Reson Med, 2008. © 2008 Wiley‐Liss, Inc.
A small‐strain overlay model
Authors: Benz T. , Vermeer P. A. , Schwab R.
Published: April 2008

The paper begins with a discussion of the phenomenon of small‐strain stiffness and presents the small‐strain overlay model, a simple model that takes into account the non‐linear stiffness of soils at small strains. The new model can enhance already established elastoplastic formulations for non‐linear stiffness variation at small strains in a similar way that intergranular strain enhances the hypoplastic model. The overlay model is driven by the material's strain history and only two additional material constants, both with clear physical meaning. Therefore, the proposed model is a step towards the incorporation of small‐strain stiffness into routine design. In this paper, the new small‐strain overlay model is formulated. Its ability to take into account the influence of various strain histories on soil stiffness is illustrated in several examples. Copyright © 2008 John Wiley & Sons, Ltd.
A model for pore‐fluid‐sensitive rock behavior using a weathering state parameter
Authors: Hickman R. J. , Gutierrez M. S. , De Gennaro V. , Delage P.
Published: April 2008

Chalk and other porous rocks are known to behave differently when saturated with different pore fluids. The behavior of these rocks varies with different pore fluids and additional deformation occurs when the pore fluid composition changes. In this article, we review the evidence that behavior in porous rocks is pore‐fluid‐dependent, present a constitutive model for pore‐fluid‐dependent porous rocks, and present a compilation of previously published data to develop quantitative relationships between various pore fluids and mechanical behavior. The model proposed here is based on a state parameter approach for weathering and has similarities to models previously proposed for weathering‐sensitive rocks in that the values for parameters that characterize material behavior vary as a function of weathering. Comparisons with published experimental data indicate that the model is capable of reproducing observed behavior of chalk under a variety of loading conditions and changes in pore fluid composition. Copyright © 2008 John Wiley & Sons, Ltd.
Lateral load distributions on grouped piles from dynamic pile‐to‐pile interaction factors
Authors: Chang Der‐Wen , Lin Bor‐Shiun , Cheng Shih‐Hao
Published: April 2008

The load distributions of the grouped piles under lateral loads acting from one side of the pile cap could be approximately modeled using the elasticity equations with the assumptions that the underground structure is rigid enough to sustain the loads, and only small deformations of the soils are yielded. Variations of the soil–pile interactions along the depths are therefore negligible for simplicity. This paper presents the analytical modeling using the dynamic pile‐to‐pile interaction factors for 2 × 2 and 2 × 3 grouped piles. The results were found comparative with the experimental and numerical results of other studies. Similar to others' findings, it was shown that the leading pile could carry more static loads than the trailing pile does. For the piles in the perpendicular direction with the static load, the loads would distribute symmetrically with the centerline whereas the middle pile always sustains the smallest load. For steady‐state loads with operating frequencies up to 30 Hz, the pile load distributions would vary significantly with the frequencies. It is interesting to know that designing the pile foundation needs to be cautioned for steady‐state vibrations as they are a problem of machine foundation. However, for transient loads or any harmonic loads acting upon relatively higher frequencies, the pile loads could be regarded as uniformly distributed. It is hoped that the numerical results of this paper will be helpful in the design practice of pile foundation. Copyright © 2008 John Wiley & Sons, Ltd.