bluuebunny/crossref_metadata_2025 huggingface dataset:
SP‐PLP‐EPR—A Novel Method for Detailed Studies into the Termination Kinetics of Radical Polymerization
Authors: Barth Johannes , Buback Michael
Published: April 2010

Single pulse–pulsed laser polymerization–electron paramagnetic resonance (SP‐PLP‐EPR) has been introduced as a powerful method for the very detailed analysis of termination kinetics. During polymerization an intense laser pulse is applied in order to almost instantaneously produce a burst of radicals. The decay of radical concentration is measured by highly time‐resolved EPR and is analyzed with respect to the rate coefficients for the termination of two radicals of identical size. SP‐PLP‐EPR experiments have been carried out for an itaconate monomer, for several methacrylates in bulk and in a solution of ionic liquids, for methacrylic acid in aqueous solution, and for the solution polymerization of butyl acrylate in toluene at low temperature. The data fully support the composite model, which assumes a stronger chain‐length dependence of termination for radicals of smaller size and a weaker one for large radicals. The SP‐PLP‐EPR technique is also applicable in systems with more than one type of growing radicals, as is the case with butyl acrylate polymerization at higher temperature and with RAFT polymerizations, where the novel method may be used for a comprehensive kinetic analysis.

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Strengthening of liquid crystalline polymer by functionalized carbon nanotubes through interfacial interaction and homogeneous dispersion
Authors: Sahoo Nanda Gopal , Cheng Henry Kuo Feng , Pan Yongzheng , Li Lin , Chan Siew Hwa , Zhao Jianhong
Published: April 2010

Multiwalled carbon nanotubes (MWCNTs) were functionalized with two types of chemical moieties (i.e. carboxylic, COOH and hydroxyl benzoic acid groups, ‐HBA) on their sidewalls in order to improve their interaction with a liquid crystalline polymer (LCP) and dispersion in LCP. We have investigated the rheological, mechanical, dynamic mechanical, and thermal properties in detail with variation of HBA‐functionalized MWCNTs in the LCP matrix. Effect of the dispersion state of the functionalized MWCNTs in the LCP matrix on the rheological behavior was also studied. The composites containing HBA‐functionalized MWCNTs showed higher complex viscosity, storage, and loss modulus than the composites with the same loading of raw MWCNTs and MWCNT‐COOH. It was suggested that the HBA‐functionalized MWCNTs exhibited a better dispersion in the polymer matrix and formed stronger CNT‐polymer interaction in the composites than the raw MWCNTs and MWCNT‐COOH, which was also confirmed by FESEM and FTIR studies. As a result, the overall mechanical performance of the HBA‐MWCNT‐LCP composites could be improved significantly. For example, the addition of 4 wt% HBA‐MWCNT to LCP resulted in the considerable improvements in the tensile strength and modulus of LCP (by 66 and 90%, respectively). Copyright © 2010 John Wiley & Sons, Ltd.
Comparison of two methods for carboplatin dosing in children with retinoblastoma
Authors: Allen Steven , Wilson Matthew W. , Watkins Amy , Billups Catherine , Qaddoumi Ibrahim , Haik Barrett H. , Rodriguez‐Galindo Carlos
Published: April 2010

Background

Carboplatin is the most effective drug in retinoblastoma but systemic clearance is variable in young patients. While most regimens use a flat dose, individualized targeting may provide a more adjusted systemic exposure.

Patients and Methods

We compared carboplatin doses between two groups of children with retinoblastoma that were treated using a flat dose of 560 mg/m2 or a targeted AUC of 6.5 using a modified Calvert formula.

Results

Ninety‐eight patients with retinoblastoma received a total of 576 cycles of carboplatin (median 8 cycles). Fifty patients (51%) received a fixed dose per m2, 32 (33%) received a dose based on AUC, 1 patient received fixed dose per kilogram, and in 15 patients a combination AUC and fixed doses was used. The median cumulative carboplatin dose (mg/m2) for patients who received eight cycles using fixed per m2 dosing was 2151.8 (range, 1414.2–2852.0), compared to 1104.1 for nine patients who received eight cycles using Calvert dosing (range, 779.0–1992.7) (P < 0.001). For cycles given using AUC, the median percentage of the hypothetical fixed per m2 dose was 70% (range, 48–134%). Younger patients had larger differences. Patients receiving carboplatin based on fixed per m2 dosing were 3.0 times more likely to have a platelet transfusion (95% confidence interval, 1.3–7.3).

Conclusions

Carboplatin administration needs to consider the changes in renal function occurring during the first months of life. The use of a targeted AUC provides the most accurate method; however, mg per kg of body weight dosing is a very reliable alternative method. Pediatr Blood Cancer 2010;55:47–54. © 2010 Wiley‐Liss, Inc.
Application of digital image correlation method to biogel
Authors: Kwon H.J. , Rogalsky Allan D. , Kovalchick Christopher , Ravichandran Guruswami
Published: April 2010

This study adopts the digital image correlation (DIC) method to measure the mechanical properties under tension in agarose gels. A second polynomial stress–strain equation based on a pore model is proposed in this work. It shows excellent agreement with experimental data and was verified by finite element simulation. Evaluation of the planer strain field by DIC allows measurement of strain localization and Poisson's ratio. At high stresses, Poisson's ratio is found to exceed the standard assumption of 0.5 which is shown to be a result of pore water leakage. Local failure strains are found to be approximately twice those determined by crosshead displacements. Viscous properties of agarose gels are investigated by performing the tensile tests at various loading rates. Increases in loading rate do not cause much difference in the shape of stress–strain curves, but result in increases in ultimate stress and strain. POLYM. ENG. SCI., 50:1585–1593, 2010. © 2010 Society of Plastics Engineers
Study of solution properties of poly(deamino‐tyr‐tyr carbonate hexyl ester) by light scattering and viscometry in dilute and semidilute regime
Authors: Aschi Adel , Trabelsi Saber , Gharbi Abdelhafidh
Published: April 2010

The structure and properties of poly(deamino‐tyr‐tyr carbonate hexyl ester), in dilute and semidilute solutions, were studied using static, dynamic light scattering, and viscometry. The overlap concentration, c* is determined by viscosity. The angular dependence of Zimm plots shows no downturn at low angles. In addition, bimodal distribution curves were computed from the quasielastic measurements. The radius of gyration and the second virial coefficient A2 are found to be respectively 45.8 nm and 9.4 mol cm3 g−2. The correlation and persistence lengths are discussed. The poly (deamino‐tyr‐tyr carbonate hexyl ester) or poly(DTH‐carbonate) chain in THF, at T = 20°C, behaves as a wormlike chain with persistence length. The persistence length obtained using light scattering is compared with that obtained using viscosity with good agreement. These values obtained from these measurements reflect a high degree of local chain persistence. The reduced viscosity in dilute regime provides a value of apparent viscosity hydrodynamic radius three times lower than obtained by static light scattering. POLYM. ENG. SCI., 50:1605–1612, 2010. © 2010 Society of Plastics Engineers
Dielectric properties of polyethylene terephthalate/polyphenylene sulfide/barium titanate nanocomposite for application in electronic industry
Authors: Konieczna Monika , Markiewicz Ewa , Jurga Jan
Published: April 2010

Polymer/ceramic nanocomposites designed for application as electronic packaging were prepared using corotating twin‐screw extruder. The dielectric properties of the composites made from polyethylene terephthalate (PET), polyphenylene sulfide, and barium titanate were studied as a function of BaTiO3 fraction in the range between 0.75 and 1.5 wt%. Processing parameters were optimized in order to obtain the nanocomposites with appropriate dielectric properties like dielectric permittivity ε′, dielectric losses ε″, and their temperature stability in a wide frequency range. The measurements showed the increase of the dielectric permittivity value ε′ in the composites in comparison to both pure polymers. The dielectric loss factor tgδ of the composites was found to be much smaller than that of the pure PET. The weak influence of the ceramics on the temperature stability of the dielectric properties of the composites was stated. POLYM. ENG. SCI., 50:1613–1619, 2010. © 2010 Society of Plastics Engineers
Dynamic mechanical properties and morphology of poly(benzyl methacrylate)/epoxy thermoset blends
Authors: Prolongo Margarita G. , Arribas Carmen , Salom Catalina , Masegosa Rosa M.
Published: April 2010

Poly(benzyl methacrylate) (PBzMA)/epoxy thermoset blends of composition 5 to 25 wt% of PBzMA were prepared curing with 4,4′diaminodiphenylmethane (DDM), to study the influence of composition on the morphology and dynamic‐mechanical properties of the blends. The cured blends are phase separated in PBzMA‐rich phase and epoxy rich‐phase. As the PBzMA content increases, the morphology evolves from nodular, to combined and to totally inverted. The analysis of the α‐mechanical relaxations indicates that the glass transition temperatures (Tg) of PBzMA and of epoxy in the blends are different from the neat polymers, this is related to a noncomplete phase separation on curing. The profiles of the loss modulus‐temperature curves are correlated with the change in morphology that appears increasing the PBzMA content. The storage modulus‐temperature curves are highly dependent on the morphology of the samples. The storage modulus‐composition dependence is predicted using several models for two phase composites. POLYM. ENG. SCI., 50:1820–1830, 2010. © 2010 Society of Plastics Engineers
Effects of carbon nanotubes and their state of dispersion on the anionic polymerization of ϵ‐caprolactam: 1. Calorimetry
Authors: Penu Christian , Hu Guo‐Hua , Fonteix Christian , Marchal Philippe , Choplin Lionel
Published: April 2010

This work reports, for the first time, on the effect of carbon nanotubes (CNT) on the kinetics of the activated polymerization of lactams. Differential scanning calorimetry (DSC) was chosen to study the kinetics of the activated anionic polymerization of ε‐caprolactam in the presence of multiwalled carbon nanotubes (MWCNT). A statistical test was carried out to confirm the validity of the experimental approach. The presence of the MWCNT slowed down the polymerization rate. This inhibiting effect depended not only on the MWCNT content but also on its state of dispersion in the polymerizing system. An autocatalytic model coupled with an evolutionary algorithm showed that the MWCNT content had an effect on the autocatalysis while its state of dispersion had an effect on the apparent polymerization kinetic constant. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Synthesis and properties of an electroactive alternating multi‐block copolymer of poly(ethylene oxide) and oligo‐aniline with high dielectric constant
Authors: Cui Lili , Chao Danming , Lu Xiaofeng , Zhang Junfeng , Mao Hui , Li Yongxin , Wang Ce
Published: April 2010

A novel electroactive polymer that has alternating oligo‐aniline and flexible poly(ethylene oxide) segments in the main chain has been synthesized through oxidative coupling polymerization. The chemical structure of the electroactive copolymer was confirmed using Fourier transform infrared and NMR spectroscopy measurements. The electrochemical activity of the copolymer was tested in 1.0 mol L−1 H2SO4 aqueous solution and it shows two redox peaks. Moreover, the thermal properties of the copolymer were investigated using thermogravimetric analysis. The copolymer obtained has good solubility in some common organic solvents. The most important properties of the copolymer are its dielectric ones, which were also investigated. It has a very high dielectric constant at room temperature. Copyright © 2010 Society of Chemical Industry
Synthesis and properties of block poly(ether‐ester)s based on poly(ethylene oxide) and various hydrophobic segments
Authors: Quattrociocchi Gianandrea , Francolini Iolanda , Martinelli Andrea , D'Ilario Lucio , Piozzi Antonella
Published: April 2010

To obtain biodegradable amphiphilic block polymers for biomedical applications, a series of poly(ether‐ester)s based on poly(ethylene oxide) and various hydrophobic/hydrophilic segment ratios were synthesized by the solution polymerization technique. The polyesters were characterized using 1H NMR spectroscopy, elemental analysis, gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis and compression stress–strain measurements. The composition of the poly(ether‐ester)s agreed with the feed ratio. A study of the degree of phase segregation in the polymers evidenced that microphase mixing increases with the presence in the hydrophobic segments of polar groups able to establish interactions with the poly(ethylene oxide). This phase mixing increased the thermal stability of the acidic poly(ether‐ester)s. Nanospheres for drug delivery with an average diameter of 50 nm were obtained by employing the acidic poly(ether‐ester) showing less microphase segregation, while a scaffold structure with a homogeneous and highly interconnected porosity and an average pore size of approximately 15 µm for tissue engineering was prepared using the more hydrophobic copolymer not possessing functional groups. Compression mechanical measurements carried out on the scaffold showed that the more hydrophobic copolymer was suitable for tissue engineering applications. In order to obtain polymers employable both in drug delivery and in tissue engineering a series of block poly(ether‐ester)s showing various phase segregations were synthesized by varying the hydrophobic/hydrophilic segment ratio. Copyright © 2010 Society of Chemical Industry
Magnetic orientation of diamagnetic amorphous polymers
Authors: Garrido Leoncio
Published: April 2010

Molecular order in an amorphous polymer with anisotropic magnetic susceptibility is altered by applying external magnetic fields. Disks of atactic polystyrene (a‐PS) are prepared by solvent casting outside or inside a magnet. The effect of the magnetic field on the polymer samples is investigated by magnetic levitation and solid state NMR spectroscopy. Magnetic levitation of the a‐PS disks shows that the orientation of disk symmetry axis with respect to the magnetic field gradient depends on the magnitude and direction of the applied field during casting. Similarly, carbon‐13 two‐dimensional cross‐polarization/magic angle spinning rotor‐synchronized NMR measurements in these samples show modulation patterns of the spinning side bands only on disks prepared in the presence of a magnetic field. These findings suggest that macromolecular order could be induced in a fluid or fluid–solid phase transition with cooperative segmental motions reorienting the diamagnetic susceptibility tensor to minimize the magnetic contribution to free energy of the sample. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1009–1015, 2010
Modification of multiwall carbon nanotubes by grafting from controlled polymerization of styrene: Effect of the characteristics of the nanotubes
Authors: Albuerne Julio , Boschetti‐de‐Fierro Adriana , Abetz Volker
Published: April 2010

Linear polystyrene chains were grown from the convex surface of two commercially available multiwall carbon nanotubes (MWCNTs) with similar diameter but different lengths. The MWCNTs were supplied from Bayer Material Science® (purity >95%, external diameter = 13–16 nm, length = 1–10 μm, denoted MWCNTBMS95) and FutureCarbon GmbH (purity >99%, external diameter = 15 nm, length = 5–50 μm, denoted MWCNTFC99). The MWCNTs were oxidized with nitric acid, consecutively reacted with thionyl chloride, glycol or poly(ethylene glycol), 2‐bromo‐2‐methylpropionyl bromide and finally with styrene under atom transfer radical polymerization (ATRP) conditions. The content of polystyrene grafted from the surface of the MWCNTs can be controlled by adjusting the molecular weight of the poly(ethylene glycol), the initiator concentration and the monomer to carbon nanotube weight ratio. Under comparable experimental conditions, a higher amount of polystyrene is grafted from the MWCNTBMS95 than from MWCNTFC99. The difference in dimensions and the state of aggregation of the carbon nanotubes influence the grafting from polymerization reactions, where relative shorter and tightly aggregated carbon nanotubes promote higher polymerizations yields than longer and less aggregated carbon nanotubes. The increase of the viscosity of the carbon nanotube dispersion decreases the polymer grafting content. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1035–1046, 2010
Can sulfur fertilisation improve the effectiveness of trap crops for diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae)?
Authors: Badenes‐Perez Francisco R , Reichelt Michael , Heckel David G
Published: April 2010

BACKGROUND:

The effect of sulfur fertilisation on chemical constituents of yellow rocket, Barbarea vulgaris (R. Br.), was studied with regard to its potential use as a trap crop for the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae). Two types of B. vulgaris var. arcuata were used: the G‐type, resistant to P. xylostella and proposed as a ‘dead‐end’ trap crop, and the P‐type, not resistant to P. xylostella and used as a control.

RESULTS:

In G‐type B. vulgaris, sulfur fertilisation increased the content of the dominant glucosinolate (S)‐2‐hydroxy‐2‐phenylethylglucosinolate by 20%. Sulfur fertilisation did not significantly change levels of the saponins 3‐0‐β‐cellobiosylhederagenin and 3‐0‐β‐cellobiosyloleanolic acid, known to act as feeding deterrents for P. xylostella larvae. In P‐type B. vulgaris, the same levels of sulfur fertilisation did not change the glucosinolate content significantly. Two‐choice oviposition preference tests with B. vulgaris plants showed that P. xylostella laid 144% and 45% more eggs on G‐ and P‐type plants with sulfur fertilisation respectively.

CONCLUSIONS:

The studies suggest that sulfur fertilisation could increase the effectiveness of G‐type B. vulgaris as a trap crop for P. xylostella. The effect of plant sulfur fertilisation on P. xylostella oviposition preference is associated with a quantitative glucosinolate increase, but other compounds could also be involved. Copyright © 2010 Society of Chemical Industry
Selective labelling of stromal cell‐derived factor 1α with carboxyfluorescein to study receptor internalisation
Authors: Bellmann‐Sickert Kathrin , Baumann Lars , Beck‐Sickinger Annette G.
Published: April 2010

SDF1α plays an important role in the regeneration of injured tissue after ischemia or stroke by inducing the migration of progenitor cells. In order to study the function of this therapeutically relevant chemokine site‐specific protein labelling is of great interest. However, modification of SDF1α is complicated because of its complex tertiary structure. Here, we describe the first site‐specific fluorescent modification of SDF1α by EPL. We recombinantly expressed SDF1α (1–49) by intein‐mediated protein expression. The C‐terminal peptide SDF1α (50–68) was synthesised by SPPS and selectively labelled with carboxyfluorescein at Lys56. In a cell migration assay, M‐[K56(CF)]SDF1α showed a clear potency to induce chemotaxis of human T‐cell leukaemia cells. Microscopic analysis on HEK293 cells transfected with the CXCR4 revealed specific binding of the fluorescent ligand. Furthermore, receptor‐induced internalisation of the ligand could be visualised. These results show that site‐specific modification of SDF1α yields in a biologically functional molecule that allows the characterisation of CXCR4 production of cells on a molecular level. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.
ZnO‐based photodetector with internal photocurrent gain
Authors: Kosyachenko L. A. , Lashkarev G. V. , Sklyarchuk V. M. , Ievtushenko A. I. , Sklyarchuk O. F. , Lazorenko V. I. , Ulyashin A.
Published: April 2010

The photoresponsive structures prepared by magnetron sputtering of ZnO on p‐Si substrates followed by vacuum evaporation of semitransparent Ni film on ZnO surface are investigated. The obtained Ni/n‐ZnO/p‐Si structures show high sensitivity that sharply increases with increase in applied voltage. Under a bias voltage of 5 V, the responsivities at λ = 390 nm and λ = 850 nm were equal to 210 and 110 A/W, which correspond to quantum efficiencies of 655 and 165, respectively. It is assumed that the observed strong response is attributed to internal gain in the Ni/n‐ZnO/p‐Si phototransistor structure containing Ni/n‐ZnO Schottky contact as the emitter junction and n‐ZnO/p‐Si heterostructure as the collector junction. The response time of the device is ∼10–7 s. Alternative mechanisms of photocurrent multiplication in such structures are also discussed.
Periodically arranged Si nanostructures by glancing angle deposition on patterned substrates
Authors: Patzig Christian , Khare Chinmay , Fuhrmann Bodo , Rauschenbach Bernd
Published: April 2010

Using glancing angle deposition (GLAD) by ion beam sputtering of Si on differently patterned substrates, periodically arranged Si nanostructures were obtained. Patterns with tetragonal, honeycomb‐like, and hexagonally closed packed (hcp) arrangement of the artificial seeds for the subsequent deposition at oblique particle incidence were used to demostrate the influence of the pattern periodicity, the inter‐seed distances, and other deposition parameters on the growth and morphological evolution of the Si nanostructures.

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Cross‐sectional scanning electron microscopy micrograph of periodically arranged Si nanospirals deposited on a tetragonally arranged template pattern.
Summer monsoon convection in the Himalayan region: terrain and land cover effects
Authors: Medina Socorro , Houze Robert A. , Kumar Anil , Niyogi Dev
Published: April 2010

During the Asian summer monsoon, convection occurs frequently near the Himalayan foothills. However, the nature of the convective systems varies dramatically from the western to eastern foothills. The analysis of high‐resolution numerical simulations and available observations from two case‐studies and of the monsoon climatology indicates that this variation is a result of region‐specific orographically modified flows and land surface flux feedbacks.

Convective systems containing intense convective echo occur in the western region as moist Arabian Sea low‐level air traverses desert land, where surface flux of sensible heat enhances buoyancy. As the flow approaches the Himalayan foothills, the soil may provide an additional source of moisture if it was moistened by a previous precipitation event. Low‐level and elevated layers of dry, warm, continental flow apparently cap the low‐level moist flow, inhibiting the release of instability upstream of the foothills. The convection is released over the small foothills as the potentially unstable flow is orographically lifted to saturation.

Convective systems containing broad stratiform echo occur in the eastern Himalayas in association with Bay of Bengal depressions, as strong low‐level flow transports maritime moisture into the region. As the flow progresses over the Bangladesh wetlands, additional moisture is extracted from the diurnally heated surface. Convection is triggered as conditionally unstable flow is lifted upstream of and over the foothills. The convective cells evolve into mesoscale convective systems (MCSs) with convective and stratiform areas. The MCSs are advected farther into the Himalayan eastern indentation, where orographic lifting enhances the stratiform precipitation. Copyright © 2010 Royal Meteorological Society
Direct determination of bromine in plastics by electrothermal vaporization/inductively coupled plasma mass spectrometry using a tungsten boat furnace vaporizer and an exchangeable sample cuvette system
Authors: Okamoto Yasuaki , Komori Hiromi , Kataoka Hiroko , Tsukahara Satoshi , Fujiwara Terufumi
Published: April 2010

A tungsten boat furnace vaporization inductively coupled plasma mass spectrometry (TBF/ICP‐MS) method has been applied to the direct determination of bromine in plastic samples. In the pretreatment, the plastic sample is spread over a small sample cuvette made of tungsten by treating it with a strongly basic organic solution, e.g., octanol or diisobutyl ketone in the presence of potassium hydroxide. The cuvette is placed on a tungsten boat furnace, with which the electrothermal vaporizer is equipped. At the vaporization step, a widely spread thin layer of the sample facilitates its efficient evaporation and introduction into an ICP mass spectrometer. The most remarkable feature is that all the bromine species in plastic samples are decomposed to form a thermally stable inorganic salt during the pretreatment procedure. Therefore, the bromine content in plastic samples can be measured by a calibration curve method constructed with an aqueous standard solution of potassium bromate(V). The detection limit (3σ) was estimated to be 0.77 pg of bromine, which corresponds to a concentration of 0.31 ng g−1 of bromine in plastic samples when a sample amount taken of 2.5 mg is studied. The relative standard deviation was calculated to be 2.2%. Analytical results of some plastic samples, which contained both inorganic bromide salts and also organic bromine species, are given. Copyright © 2010 John Wiley & Sons, Ltd.
A simplified mass isotopomer approach to estimate gluconeogenesis rate in vivo using deuterium oxide
Authors: Junghans Peter , Görs Solvig , Lang Iris S. , Steinhoff Julia , Hammon Harald M. , Metges Cornelia C.
Published: April 2010

We compare a new simplified 2H enrichment mass isotopomer analysis (MIA) against the laborious hexamethylentetramine (HMT) method to quantify the contribution of gluconeogenesis (GNG) to total glucose production (GP) in calves. Both methods are based on the 2H labeling of glucose after in vivo administration of deuterium oxide. The 2H enrichments of plasma glucose at different C‐H positions were measured as aldonitrile pentaacetate (AAc) and methyloxime‐trimethylsilyl (MoxTMS) derivatives or HMT by gas chromatography/mass spectrometry (GC/MS). Two pre‐ruminating fasted Holstein calves (51 kg body mass, BM, age 7 days) received two oral bolus doses of 2H2O (10 g/kg BM, 70 atom% 2H) at 7:00 h and 11:00 h after overnight food withdrawal. Blood samples for fractional GNG determination were collected at −24 and between 6 and 9 h after the first 2H2O dose. The ratio of 2H enrichments C5/C2 represents the contribution of GNG to GP. The 2H enrichment at C2 was calculated based on the ion fragments at m/z 328 (C1‐C6) ‐ m/z 187 (C3‐C6) of glucose AAc. The 2H enrichment at C5 was approximated either by averaging the 2H enrichment at C5‐C6 using the ion fragment of glucose MoxTMS at m/z 205 or by conversion of the C5 of glucose into HMT. The fractional GNG calculated by the C5‐C6 average 2H enrichment method (41.4 ± 6.9%) compared to the HMT method (34.3 ± 11.4%) was not different (mean ± SD, n = 6 replicates). In conclusion, GNG can be estimated with less laborious sample preparation by means of our new C5‐C6 average 2H enrichment method using AAc and MoxTMS glucose derivatives. Copyright © 2010 John Wiley & Sons, Ltd.
Quantification of methane in humid air and exhaled breath using selected ion flow tube mass spectrometry
Authors: Dryahina Kseniya , Smith D. , Španěl P.
Published: April 2010

In selected ion flow tube mass spectrometry, SIFT‐MS, analyses of humid air and breath, it is essential to consider and account for the influence of water vapour in the media, which can be profound for the analysis of some compounds, including H2CO, H2S and notably CO2. To date, the analysis of methane has not been considered, since it is known to be unreactive with H3O+ and NO+, the most important precursor ions for SIFT‐MS analyses, and it reacts only slowly with the other available precursor ion, O. However, we have now experimentally investigated methane analysis and report that it can be quantified in both air and exhaled breath by exploiting the slow O/CH4 reaction that produces CH3O ions. We show that the ion chemistry is significantly influenced by the presence of water vapour in the sample, which must be quantified if accurate analyses are to be performed. Thus, we have carried out a study of the loss rate of the CH3O analytical ion as a function of sample humidity and deduced an appropriate kinetics library entry that provides an accurate analysis of methane in air and breath by SIFT‐MS. However, the associated limit of detection is rather high, at 0.2 parts‐per‐million, ppm. We then measured the methane levels, together with acetone levels, in the exhaled breath of 75 volunteers, all within a period of 3 h, which shows the remarkable sample throughput rate possible with SIFT‐MS. The mean methane level in ambient air is seen to be 2 ppm with little spread and that in exhaled breath is 6 ppm, ranging from near‐ambient levels to 30 ppm, with no significant variation with age and gender. Methane can now be included in the wide ranging analyses of exhaled breath that are currently being carried out using SIFT‐MS. Copyright © 2010 John Wiley & Sons, Ltd.
Minimizing analyte electrolysis in electrospray ionization mass spectrometry using a redox buffer coated emitter electrode
Authors: Peintler‐Krivan Emese , Van Berkel Gary J. , Kertesz Vilmos
Published: April 2010

An emitter electrode with an electroactive poly(pyrrole) (PPy) polymer film coating was constructed for use in electrospray ionization mass spectrometry (ESI‐MS). The PPy film acted as a surface‐attached redox buffer limiting the interfacial potential of the emitter electrode. While extensive oxidation of selected analytes (reserpine and amodiaquine) was observed in positive ion mode ESI using a bare metal (gold) emitter electrode, the oxidation was suppressed for these same analytes when using the PPy‐coated electrode. A semi‐quantitative relationship between the rate of oxidation observed and the interfacial potential of the emitter electrode was shown. The redox buffer capacity, and therefore the lifetime of the redox buffering effect, correlated with the oxidation potential of the analyte and with the magnitude of the film charge capacity. Online reduction of the PPy polymer layer using negative ion mode ESI between analyte injections was shown to successfully restore the redox buffering capacity of the polymer film to its initial state. Published in 2010 by John Wiley & Sons, Ltd.
Microstructural Evolution and Change in Hardness of S30432 Heat‐resistant Steel during Creep at 650 °C
Authors: Zhu L.H. , Zhang Y.J. , Wang Q.J. , Xu S.Q.
Published: April 2010

The microstructural evolution of S30432 heat‐resistant steel during creep at 650 °C and its effect on the change in hardness was investigated. The change of hardness during creep of S30432 at 650 °C can be divided into three stages. These are related to the precipitation and coarsening of ε‐Cu and M23C6 carbides, decrease in the number of twins and increase in grain size. The precipitation of ε‐Cu dominantly contributes to the significant hardening at stage I, and the coarsening of ε‐Cu is the key factor to decrease the hardness at stage II. At stage III, the hardness hardly changes since the microstructure of S30432 tends to be stable in the long‐term creep range.
Fatigue and Structural Changes of High Interstitial Stainless Austenitic Steels
Authors: Berns H. , Gavriljuk V.G. , Nabiran N. , Petrov Yu.N. , Riedner S. , Trophimova L.N.
Published: April 2010

Steels with 18 to 19 mass% Cr and Mn each were studied in the as‐cast condition containing 0.85 mass% C + N and in the elektro‐slag‐remelted and hot worked condition containing 0.96 mass% C + N after final solution annealing. The latter was also tested after 20% prestraining. The results of tensile tests were compared to those of rotating bending and push/pull loading. The higher C + N content raised the 0.2% proof strength to about 600 MPa of which 70% were retained as fatigue limit of rotating bending at 107 cycles and a failure probability of 50%. Prestraining further improved this limit but lowered it in relation to the proof strength. The structural components of cold work hardening under unidirectional loading and cyclic loading were similar (planar slip, dislocation, twins and ε‐martensite) except for precipitates in the latter. Nitrides appeared in the austenite and carbides in the ε‐plates.
The Effect of MgO on the Viscosity of the CaO‐SiO2‐20  wt%Al2O3‐MgO Slag System
Authors: Kim Hyuk , Kim Wan Ho , Sohn Il , Min Dong Joon
Published: April 2010

The viscosities of CaO‐SiO2‐20 wt%Al2O3‐MgO slags (CaO/SiO2 = 1.0–1.2, wt%MgO = 5–13) were measured to estimate the effect of MgO on the viscous behaviour at elevated temperatures. The slag viscosity at 1773 K decreased with increasing MgO contents, which was typical of a basic oxide component at relatively low basicity (CaO/SiO2) of 1.0. The FT‐IR spectroscopic analysis of the slag structure seems to verify this behaviour. However, an unexpected contradiction with the temperature dependence was observed above 10 wt%MgO and above CaO/SiO2 of 1.2. Although the apparent activation energy was expected to decrease with additions of the basic oxide component MgO, the apparent activation energy increased. This unexpected behaviour seems to be related to the change in the primary phase field correlating to the phase diagram corresponding to the slag composition. Therefore, in order to understand the viscosity at both high Al2O3 and MgO, not only should the typical depolymerization of the slag structure with high MgO content be considered but also the primary phases of which the molten slag originates.
Sustained release properties of cross‐linked corn starches with varying amylose contents in monolithic tablets
Authors: Onofre Fernanda O. , Mendez‐Montealvo Guadalupe , Wang Ya‐Jane
Published: April 2010

Corn starches of varying amylose contents (0, 28, and 70%) were cross‐linked with epichlorohydrin to different levels (0.01, 0.05, and 0.1% w/w starch dry basis), and their sustained release properties in tablets were evaluated using propranolol hydrochloride as the model drug. Drug release was correlated with swelling power of the cross‐linked starches, porosity of tablets, and rheological properties of the swollen tablets. Cross‐linking increased the drug release rate from starch tablets, and had a stronger impact on amylose‐containing starch matrices than on waxy corn starch ones. The cross‐linked starches showed lower swelling power and produced tablets of lower porosity than their respective non‐cross‐linked controls. Increasing cross‐linking led to progressively more rigid and stiffer waxy corn starch matrices, but it had the opposite effect on high amylose corn ones, and an intermediate effect on common corn ones. The amylose content played an important role in the properties of starch matrices, and consequently the sustained release and rheological behavior of starch tablets.
Relationship of cooked‐rice nutritionally important starch fractions with other physicochemical properties
Authors: Patindol James , Guraya Harmeet , Champagne Elaine , Chen Ming‐Hsuan , McClung Anna
Published: April 2010

Sixteen rice cultivars representing five cytosine‐thymine repeat (CTn) microsatellite genetic marker groups were analyzed for their cooked rice nutritionally important starch fractions (NISFs, which include rapidly digestible (RDS), slowly digestible (SDS), and resistant starch (RS)), basic grain quality indices (apparent amylose (AM), crude protein (CP), alkali spreading value (AS), and gel consistency (GC)), pasting characteristics, and thermal properties. Chemometric tools (bivariate correlation, principal component analysis, multiple linear regression, and partial least squares regression) were used to establish the association of NISF with other milled rice physicochemical properties. CT11 was generally associated with high percentages of RS and SDS, and a low percentage of RDS. CT14 was associated with low SDS; whereas, CT17 and CT18 were associated with low RS. The CT20 cultivars were similar to CT11 in SDS and RS; and to CT14, CT17, and CT18 in RDS content. RDS, SDS, and RS were loaded on three different quadrants of the principal component similarity map. RDS was not significantly correlated with any of the physicochemical properties; whereas, SDS was positively correlated with GC. RS was positively correlated with AM, setback (SB) viscosity, total setback (TSB) viscosity, and peak gelatinization temperature; and negatively correlated with breakdown (BD) viscosity. Multivariate techniques indicated lack of robustness in predicting RDS and SDS as the models only explained <50% of the variance. More robust regression models were obtained for RS, explaining >60% of its variation. Basic grain quality indices explained NISF variations better than pasting and thermal properties.
Permanently Blocked Stem Cells Derived From Breast Cancer Cell Lines
Authors: Sajithlal Gangadharan B. , Rothermund Kristi , Zhang Fang , Dabbs David J. , Latimer Jean J. , Grant Stephen G. , Prochownik Edward V.
Published: April 2010

Cancer stem cells (CSCs) are thought to be resistant to standard chemotherapeutic drugs and the inimical conditions of the tumor microenvironment. Obtaining CSCs in sufficient quantities and maintaining their undifferentiated state have been major hurdles to their further characterization and to the identification of new pharmaceuticals that preferentially target these cells. We describe here the tagging of CSC-like populations from four human breast cancer cell lines with green fluorescent protein (GFP) under the control of the Oct3/4 stem cell-specific promoter. As expected, GFP was expressed by the CSC-enriched populations. However, an unanticipated result was that these cells remained blocked in a CSC-like state and tended to be resistant to chemotherapeutic drugs as well as acidotic and hypoxic conditions. These CSC-like cells possessed several other in vitro attributes of CSCs and were able to reproducibly generate tumors in immunocompromised mice from as few as 100 cells. Moreover, the tumors derived from these cells were comprised almost exclusively of pure CSCs. The ability of the Oct3/4 promoter to block CSC differentiation underscores its potential general utility for obtaining highly purified CSC populations, although the mechanism by which it does so remains undefined and subject to further study. Nonetheless, such stable cell lines should be extremely valuable tools for studying basic questions pertaining to CSC biology and for the initial identification of novel CSC-specific chemotherapeutic agents, which can then be verified in primary CSCs.
Vakuumimprägnierung poröser Metallwerkstücke mit anorganischen Nanosolen
Authors: Mahltig Boris
Published: April 2010

Die Versiegelung von porösen Metallwerkstücken kann durch Anwendung von anorganischen Nanosolen gelingen. entscheidend für die wirksame Versiegelung ist die Applikation der Nanosole mittels Vakuumimprägnierung. Geeignete Nanosole enthalten Partikel von Silizium/Aluminium‐Mischoxiden, die zudem mit organischen Methylgruppen modifiziert sind. Die Nanosolpartikel sind kleiner 100 nm, wobei das Maximum der Größenverteilung bei etwa 10nm liegt. Neben der Versiegelung von Metallwerkstücken kann zudem durch die Nanosol‐Applikation eine Verbesserung der Korrosionsstabilität erreicht werden. Eine Weiterentwicklung dieser Technologie ist somit insbesondere aussichtsreich für Anwendungen im Werkzeugbau und für Werkstücke im Automobilbau.
Bilingualism
Authors: Bialystok Ellen
Published: April 2010

The cognitive and linguistic processes involved in the acquisition and use of two languages are systematically different from those processes engaged in monolingual language use, leading to detectable changes in language and cognitive outcomes for bilinguals. The present article describes these differences and offers speculation on possible mechanisms. Measures of linguistic proficiency and processing are often poorer in bilinguals than in monolinguals: bilingual children have a smaller vocabulary in each language than comparable monolingual children in that language and bilingual adults take longer to retrieve specific words than monolinguals. In contrast, measures of nonverbal executive control, including the ability to selectively attend to relevant information, inhibit distraction, and shift between tasks is generally better in bilinguals than in monolinguals. These two types of outcomes are illustrated and explained through behavioral and neuroimaging evidence. The implications of these effects of bilingualism on cognitive and linguistic processing are considered in terms of both their clinical and theoretical consequences. Copyright © 2010 John Wiley & Sons, Ltd.

This article is categorized under:

Linguistics > Language in Mind and Brain

Psychology > Language
Variations in Eastern bongo (Tragelaphus eurycerus isaaci) feeding practices in UK zoological collections
Authors: Wright D. J. , Omed H. M. , Bishop C. M. , Fidgett A. L.
Published: April 2010

The feeding strategy of the Eastern bongo in the wild is unusual, poorly understood, and few captive feeding recommendations are currently available to zoos. To assess the current state of nutritional husbandry of this rare antelope, eight UK zoos were surveyed. A nutritional husbandry questionnaire was completed and bongos at each zoo were visually assessed by body condition scoring (BCS). Representative samples of the forage and browse consumed by bongos at each zoo were analyzed for nutrient composition using standard agricultural techniques. Significant differences in bongo body condition were found, indicating that zoo husbandry practices are sufficiently varied to have identifiable impacts on the physical condition of the animals. The results highlight a disparity in feeding regimes and diet quality, with significant differences found in forage and browse nutrient compositions and in vitro digestibility. Most forage samples were of a low nutritional quality. Browse provision was found to be largely opportunistic and limited in most zoos. The provision of energy‐rich produce was also found to be unnecessary in maintaining a bongo herd at an ideal mean BCS. This survey provides baseline data which may be useful in establishing “good practice” standards for Eastern bongo captive nutrition and highlights several areas requiring further research. Zoo Biol 30:149–164, 2011. © 2010 Wiley‐Liss, Inc.
Bilateral Internal Jugular Venous Sampling for Parathyroid Hormone Determination in Patients with Nonlocalizing Primary Hyperparathyroidism
Authors: Alvarado Raul , Meyer‐Rochow Goswin , Sywak Mark , Delbridge Leigh , Sidhu Stan
Published: April 2010

Background

Focused parathyroidectomy (FP) is offered to 60% to 70% of patients presenting to our unit with primary hyperparathyroidism (PHPT). A recent report identified bilateral internal jugular venous sampling (BIJVS) as a useful tool for localization of parathyroid adenomas in patients with scan‐negative PHPT. The purpose of this study was to evaluate the utility of this approach in a clinical setting.

Methods

A prospective case‐control trial was undertaken. Bilateral internal jugular venous blood samples were obtained. Patients were stratified into three groups: Group A consisted of patients with a negative sestamibi scan undergoing bilateral exploration; group B consisted of patients undergoing FP following a positive sestamibi scan; and group C patients were a control group undergoing total thyroidectomy.

Results

In group A, 17 of 30 patients (56%) had lateralization of the parathyroid hormone (PTH) levels, with 11 correctly lateralizing to the side of the adenoma, 5 lateralizing despite bilateral disease, and 1 lateralizing to the contralateral side. Of the remaining 13 patients in whom there was no lateralization, 3 had bilateral multigland disease, and 10 had a single parathyroid adenoma. In group B, 17 of 30 patients (56%) also had lateralization of PTH levels, with 15 lateralizing to the side of the adenoma and 2 to the contralateral side. Lateralization failed in the remaining 13 patients, although in all of these patients the calcium and PTH levels normalized postoperatively. The control group of patients without parathyroid disease (group C) demonstrated lateralization of PTH levels in 23 of 30 patients (76%).

Conclusions

In our hands, BIJVS for PTH determination was not a useful adjunctive test facilitating FP. We continue to offer all patients with PHPT and a negative sestamibi scan a standard bilateral neck exploration.
Analysis of 5‐Year Survivors After a Macroscopic Curative Pancreatectomy for Invasive Ductal Adenocarcinoma
Authors: Shimada Kazuaki , Sakamoto Yoshihiro , Nara Satoshi , Esaki Minoru , Kosuge Tomoo , Hiraoka Nobuyoshi
Published: April 2010

Background

Surgical resections for invasive ductal adenocarcinoma of the pancreas can provide the only chance of cure, although the 5‐year survivors are not always equated with cure.

Methods

A total of 229 who underwent a macroscopic curative pancreatectomy for invasive ductal adenocarcinoma between 1990 and 2003 and have been observed for more than 5 years from the time of resection were retrospectively analyzed. The data of patients who survived more than 5 years were compared with those died within 5 years. The recurrence pattern and factors that influenced an additional 5‐year survival in the 5‐year survivors were investigated.

Results

Forty patients (17%) survived more than 5 years, and the survival rate for an additional 5 years after surviving 5 years was 72%. A multivariate Cox hazards analysis showed that negative surgical margins status, less frequency of lymphatic invasion, stage ≤ IIB, and negative lymph node involvement were independent factors associated with long‐term survival. Thirty patients (75%) were alive without recurrence, and eight (20%) died of disease within 7.3 years. Intrapancreatic nerve invasion was a significant factor predicting additional long‐term survival in the 40 5‐year survivors.

Conclusions

Limited cancer extension with negative lymph node metastases significantly contributes to the chance of surviving more than 5 years. A low incidence of intrapancreatic nerve invasion in the 5‐year survivors affects the subsequent favorable survival.