bluuebunny/crossref_metadata_2025_split huggingface dataset:
In situ polymerization and characterization of polyester‐based polyurethane/nano‐silica composites
Authors: Chen Xichong , Wu Limin , Zhou Shuxue , You Bo 
Published: May 2003

AbstractPolyester‐based polyurethane/nano‐silica composites were obtained via in situ polymerization and investigated by Fourier‐transform infrared spectroscopy (FTIR), or FTIR coupled with attenuated total reflectance (FTIR‐ATR), Transmission electron microscopy (TEM), atomic force microscopy (AFM), an Instron testing machine, dynamic mechanical analysis (DMA) and ultraviolet‐visible spectrophotometry (UV‐vis). FTIR analysis showed that in situ polymerization provoked some chemical reactions between polyester molecules and nano‐silica particles. FTIR‐ATR, TEM and AFM analyses showed that both surface and interface contained nano‐silica particles. Instron testing and DMA data showed that introducing nano‐silica particles into polyurethane enhanced the hardness, glass temperature and adhesion strength of polyurethane to the substrate, but also increased the resin viscosity. UV‐vis spectrophotometry showed that nano‐silica obtained by the fumed method did not shield UV radiation in polyurethane films. Copyright © 2003 Society of Chemical Industry
Synthesis and solution properties of alternating maleimide/styrene hyperbranched copolymers via controlled radical mechanism
Authors: Ishizu Koji , Takashimizu Chisato , Shibuya Takeshi , Uchida Satoshi 
Published: May 2003

AbstractCopolymerizations of (N,N‐diethyldithiocarbamyl)methylstyrene (inimer: DTCS) with maleimide (MI) were carried out under UV irradiation. DTCS monomers play an important role in this copolymerization system as an inimer that is capable of initiating radical polymerization of the vinyl group. Reactivity ratios (r1 = 0.15 and r2 = 0) were estimated by the curve‐fitting procedure (DTCS [M1]; MI[M2]). These reactivities show strong alternation, and the propagating copolymer radicals proceed with homopolymerization of 1:1 complexes formed between the donor and acceptor monomers. These alternating copolymers exhibit highly branched structure and are actually hyperbranched copolymers. The compact nature of the hyperbranched molecules was demonstrated by comparison of their dilute‐solution properties with those of the linear analogues. The hyperbranched macromolecules behave as single, well‐separated molecules (even in good solvent) and as hard spheres. Copyright © 2003 Society of Chemical Industry
Effect of synthesis parameters on the electrical conductivity of polypyrrole‐coated poly(ethylene terephthalate) fabrics
Authors: Kaynak Akif , Beltran Rafael 
Published: May 2003

AbstractThe effects of pyrrole, anthraquinone‐2‐sulphonic acid (AQSA) and iron(III) chloride (FeCl3) concentrations, reaction time and temperature on the electrical conductivity of polypyrrole (PPy)—coated poly(ethylene terephthalate) (PET) fabrics were investigated. With an increase in both the AQSA and FeCl3 concentrations, resistivity decreased to a point beyond which higher concentrations led to increased surface resistivity. Erosion of the polymer coating, in dynamic synthesis from continual abrasion, manifested as an exponential increase in the resistance of the coated textile substrate. This was not encountered in static synthesis conditions. Temperature affected the degree of surface and bulk polymerisation. The effect of polymerisation temperature on conductivity was negligible. Conductive polymer coating on textiles through chemical polymerisation enabled a smooth coherent film to encase individual fibres, which did not affect the tactile properties of the host substrate. The optimum FeCl3/pyrrole and AQSA FeCl3/pyrrole molar ratios were found to be 2.22 and 0.40 respectively. Copyright © 2003 Society of Chemical Industry
Flammability and thermal stability studies of ABS/Montmorillonite nanocomposite
Authors: Wang Shaofeng , Hu Yuan , Lin Zhihua , Gui Zhou , Wang Zhengzhou , Chen Zuyao , Fan Weicheng 
Published: May 2003

AbstractAcrylonitrile–butadiene–styrene (ABS)/montmorillonite nanocomposites have been prepared using a direct melt intercalation technique by blending ABS and organophilic clay of two different particle sizes: OMTa (5 µm) and OMTb (38 µm). Their structure and flammability properties were characterized by X‐ray diffraction, high resolution electronic microscopy (HREM), thermogravimetric analysis (TGA) and cone calorimeter experiments. The results of HREM showed that ABS/5 wt% OMTa nanocomposite was a kind of intercalated–delaminated structure, while ABS/5 wt% OMTb nanocomposite was mainly an intercalated structure. The nanocomposites showed a lower heat release rate peak and higher thermal stability than the original ABS by TGA and cone calorimeter experiments. Also, the intercalated nanocomposite was more effective than an exfoliated–intercalated nanocomposite in fire retardancy. Copyright © 2003 Society of Chemical Industry
Interpolymer complexes of novel linear and crosslinked acrylic acid–Schiff base copolymers
Authors: Zhumadilova Gulmira , Yashkarova Marziya , Bimendina Larisa , Kudaibergenov Sarkyt 
Published: May 2003

AbstractNovel linear and crosslinked copolymers of acrylic acid and Schiff base, containing the amine groups in the main chain and the carboxylic groups in the side chain, have been synthesized by the Michael addition reaction followed by radical copolymerization. The copolymers that exhibited poly(ampholyte–electrolyte) behaviour were used to prepare complexes by reaction with anionic (poly(acrylic acid), poly(styrene sodium sulfonate)), cationic (polyethyleneimine, poly(hexamethylene guanidine)) and non‐ionic (poly(N‐vinylpyrrolidone), poly(ethylene glycol), poly(vinyl alcohol)) polymers. The influence of external factors, such as solvent quality, temperature, pH and ionic strength, on phase (coil–globule) and volume (swelling–collapse) transitions has been studied.© 2003 Society of Chemical Industry
Mössbauer, infrared, and X‐ray studies of Ti‐doped CoCr1.2Fe0.8O4 ferrites
Authors: Amer M. A. 
Published: May 2003

AbstractThe spinel samples Co1+xTixCr1.2–2xFe0.8O4 (0 ≤ x ≤ 0.6) were investigated at room temperature using Mössbauer, X‐ray, and IR spectra. The Mössbauer spectra for x ≤ 0.1 showed only broad six‐lines patterns and for 0.2 ≤ x ≤ 0.5 showed, in addition to the broad six‐lines patterns, a central paramagnetic phase C. The spectrum for x = 0.6 showed only paramagnetic phase C. The six‐lines patterns were analysed to two magnetic patterns attributed to Fe3+ ions on the tetrahedral A‐sites and to Fe2+ and Fe3+ ions on the octahedral B‐sites. The broader B‐site pattern appeared to be composite for x ≤ 0.3, thus it has been analysed to its multicomponents. The paramagnetic phase C was analysed to two quadrupole doublets due to Fe3+ ions at the A‐ and B‐sites. The obtained hyperfine interaction parameters have been studied and discussed as functions of the composition factor x. The cation distributions have been estimated and supported by X‐ray studies. Six absorption bands were observed in the IR spectra and attributed to Fe3+ ions on the A‐ and B‐sites, to Fe2+ and Co2+ ions, and to the energy of the sublattices. The IR bands revealed the existence of Fe2+ ions in the samples. The true and theoretical lattice parameters, the oxygen positional parameter, and the ionic radii, bonds, and edges of the A‐ and B‐sites have been determined from the X‐ray analysis. They were studied and discussed in dependence of x.
Weak localization and the Mooij rule in disordered metals
Authors: Park Mi‐Ae , Savran Kerim , Kim Yong‐Jihn 
Published: May 2003

AbstractWeak localization leads to the same correction to both the conductivity and the McMillan's electron–phonon coupling constantλ(andλtr, transport electron–phonon coupling constant). Consequently the temperature dependence of the thermal electrical resistivity is decreasing as the conductivity is decreasing due to weak localization, which results in the decrease of the temperature coefficient of resistivity (TCR) with increasing the residual resistivity. Whenλandλtrare approaching zero, only the residual resistivity part remains and it gives rise to the negative TCR. Accordingly, the Mooij rule is a manifestation of weak localization correction to the conductivity and the electron–phonon interaction. This understanding provides a new means of probing the phonon‐mechanism in exotic superconductors and an opportunity of fabricating new novel devices.
Magnetic characteristics and band structure calculations of Y2Co7–xNixB3 compounds
Authors: Mincic A. , Pop V. 
Published: May 2003

AbstractThe Y2Co7–xNixB3 compounds crystallize in a hexagonal structure of the Ce2Co7B3‐type for x ≤ 4. Magnetic measurements were performed in the temperature range 4–800 K and in fields up to 8 T. The compounds with x ≤ 3 are ferromagnetically ordered. Y2Co3Ni4B3 is found to be paramagnetic in the studied temperature range. The experimental data were compared with the results obtained from band structure calculations using the TB‐LMTO method in the ASA approximation. The magnetic behavior of cobalt in these compounds is analyzed within the theory of spin fluctuations.
Evidence of non‐adiabatic small polaron hopping conduction in Bi0.1A0.9MnO3 (A = Ca, Sr, Pb)
Authors: Pal Sudipta , Banerjee Aritra , Chatterjee P. , Chaudhuri B. K. 
Published: May 2003

AbstractA detailed study of the electrical transport properties of semiconducting perovskites Bi0.1A0.9MnO3 (A = Ca, Sr, Pb of increasing ionic radius ri) have been made over a wide range of temperature 80–375 K. XRD studies indicate a change of structural differences with change of ionic radius ri of A. The dc conductivity of the Sr‐ and Pb‐doped samples with larger ri is much lower than that of the Ca‐doped sample of smaller ri. Unlike the Sr‐ and Pb‐doped samples, little negative magnetoresistance is also observed in the Ca‐doped sample (below 115 K at 1.5 T field). The resistivity data below θD/2 (θD is the Debye temperature) are fitted well with the Mott's variable range hopping (VRH) model, whereas the nearest‐neighbour small polaron hopping mechanism satisfactorily fitted the high‐temperature (above θD/2 ≈ 200 K) conductivity data. The condition of the non‐adiabatic small polaron hopping mechanism is valid for all the samples. The estimated electron–phonon interaction constant γp (= 2WH/hνph) of the highly resistive Sr‐ and Pb‐doped samples are much higher (≫4) than those of the low‐resistive Ca‐doped oxide sample (≈4). Large values of γp destroy spin ordering in the Sr‐ and Pb‐doped samples, while for the lower value of γp in the Ca‐doped sample spin ordering favours high conductivity and show a negative magnetoresistance (only in the low‐temperature region). Low‐temperature (T < θD/2) frequency‐dependent ac conductivity data indicate that the conduction mechanism in the highly resistive Sr‐ and Pb‐doped samples is primarily due to hopping of Anderson‐localized charge carriers.
Studies on the electrical conduction in silver telluride thin films
Authors: Gnanadurai P. , Soundararajan N. , Sooriamoorthi C. E. 
Published: May 2003

AbstractThe temperature dependence of the electrical resistance of unannealed and annealed silver telluride thin films of different thickness between 30 and 110 nm, prepared by thermal evaporation at a pressure of 2 × 10–5 mbar, has been studied. The films are polycrystalline. It is found that metastable defects influence the phase transition in unannealed films. The annealed films undergo a structural phase transition at around 410 K during heating and at around 380 K during cooling. Similar hysteresis has also been observed in the phase transition of bulk material in differential scanning calorimetry studies. It is found that the resistivity of silver telluride thin films decreases with decrease in film thickness. This may be due to the generation of free carriers by the increase of Frenkel defects due to silver atoms.
Deep and edge photoluminescence emission of CuInTe2
Authors: Jagomägi Andri , Krustok Jüri , Raudoja Jaan , Grossberg Maarja , Danilson Mati 
Published: May 2003

AbstractPhotoluminescence studies of chalcopyrite CuInTe2 were conducted. Three edge (1.041 eV, 1.030 eV, and 1.019 eV) and two deep level (0.999 eV and 0.957 eV) emission bands were observed at 11 K. The excitation intensity dependence of PL spectra was recorded. As possible band sources one excitonic and four band‐to‐defect recombination mechanisms are proposed in this paper.
The Wiener Index of simply generated random trees
Authors: Janson Svante 
Published: May 2003

AbstractAsymptotics are obtained for the mean, variance, and higher moments as well as for the distribution of the Wiener index of a random tree from a simply generated family (or, equivalently, a critical Galton–Watson tree). We also establish a joint asymptotic distribution of the Wiener index and the internal path length, as well as asymptotics for the covariance and other mixed moments. The limit laws are described using functionals of a Brownian excursion. The methods include both Aldous' theory of the continuum random tree and analysis of generating functions. © 2003 Wiley Periodicals, Inc. Random Struct. Alg., 22: 337–358, 2003
Regular pairs in sparse random graphs I
Authors: Kohayakawa Y. , Rödl V. 
Published: May 2003

AbstractWe consider bipartite subgraphs of sparse random graphs that are regular in the sense of Szemerédi and, among other things, show that they must satisfy a certain local pseudorandom property. This property and its consequences turn out to be useful when considering embedding problems in subgraphs of sparse random graphs. © 2003 Wiley Periodicals, Inc. Random Struct. Alg., 22: 359–434, 2003
A note on scrambling permutations
Authors: Radhakrishnan Jaikumar 
Published: May 2003

AbstractA family ℱ of permutations of [n] is completely k‐scrambling [Spencer,1972] if for every sequence 〈p1, p2, …, pk〉 of k distinct elements of [n], there is a permutation π ∈ ℱ with π(p1) < π(p2) < … < π(pk). We show that the size of the smallest completely k‐scrambling family of permutations of [n] is at least

This improves the previous best lower bound, due to Füredi 1996, by a factor of approximately 2/log2e. © 2003 Wiley Periodicals, Inc. Random Struct. Alg., 22: 435–439, 2003
Notes on the variance of the number of maxima in three dimensions
Authors: Carlsund Anna 
Published: May 2003

AbstractWe study the number of maxima on a d‐dimensional cube. We give an exact expression for the variance in three dimensions, which is easy to express as a polynomial in log n and therefore can be compared with approximations. © 2003 Wiley Periodicals, Inc. Random Struct. Alg., 22: 440–447, 2003
Intrapartum assessment of fetal head engagement: comparison between transvaginal digital and transabdominal ultrasound determinations
Authors: Sherer D. M. , Abulafia O. 
Published: May 2003

AbstractObjectiveTo test the null hypothesis that no correlation exists between transvaginal digital examination and the gold standard technique of intrapartum transabdominal ultrasound determination of fetal head engagement, and secondarily to compare the performance of attending physicians and senior residents in depicting fetal head engagement by transvaginal digital examination.MethodsTwo hundred and twenty‐two consecutive patients in labor > 37 weeks' gestation with normal singleton cephalic‐presenting fetuses and with either ruptured or intact membranes were included. Of these, 119 were nulliparous and 103 were multiparous. Transvaginal digital examinations were performed by either attending physicians or senior residents and were followed immediately by transverse suprapubic sonographic assessments by a single sonographer. The fetal head was considered engaged on transvaginal digital examination if the leading part of the fetal head was positioned at least at maternal ischial spine station 0, and on transverse suprapubic ultrasound if the fetal biparietal diameter was below the maternal pelvic inlet. Examiners were blinded to each other's findings and the effect of examiner experience on the rate of agreement between the two techniques was assessed. The effect of several other independent variables upon the rate of agreement between the two modalities was also assessed.ResultsOverall, transvaginal digital examinations were consistent with ultrasound determinations with a raw percent agreement rate of 85.6% (95% confidence interval (CI), 80.8–90.3); κ = 69.5% (95% CI, 59.4–73.9; P < 0.001). When stratified according to parity, the raw percent agreement rate for nulliparous patients was 81.5% (95% CI, 73.4–88.0); κ = 60.7% (95% CI, 45.9–64.1; P < 0.001), and for multiparous patients it was 90.3% (95% CI, 84.1–95.9); κ = 80.4% (95% CI, 63.0–87.5; P < 0.001). Maternal age, gravidity, maternal body mass index, gestational age, cervical dilatation, effacement, membrane status, ischial spine station of the fetal head, fetal head position at ultrasound assessment, birth weight and mode of delivery did not significantly affect rate of agreement. Parity did not affect examination consistency in multiparous patients, but in the whole group increasing parity increased the rate of agreement between modalities. Presence of combined spinal epidural anesthesia significantly increased the rate of agreement in the complete group and among multiparous but not among nulliparous patients.ConclusionThese data demonstrate a high rate of agreement (85.6%) between ultrasound determination and transvaginal digital assessment of fetal head engagement. Examiner experience had no effect. These data support the use of intrapartum transabdominal assessment of fetal head engagement. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Reference values for an index of fetal aortic isthmus blood flow during the second half of pregnancy
Authors: Ruskamp J. , Fouron J.‐C. , Gosselin J. , Raboisson M.‐J. , Infante‐Rivard C. , Proulx F. 
Published: May 2003

AbstractObjectiveDuring fetal life, the parallel position of the two cardiac ventricles confers a special status to the aortic isthmus. Flow through the isthmus reflects the balance between the performances of the two ventricles and their respective peripheral impedances. This study proposes a fetal aortic isthmus flow velocity index and its reference values defined on the basis of gestational age (GA).MethodsVideo recordings of 111 normal fetuses from 18 to 39 weeks of gestation were retrospectively reviewed. An isthmus flow velocity index (IFI) was calculated as follows: IFI = (systolic + diastolic)/systolic velocity integrals. GA‐specific reference ranges of IFI were constructed.ResultsAn IFI of 1.33 ± 0.03 was found at 18 weeks. This value decreased slightly but steadily with GA to reach 1.23 ± 0.16 at 39 weeks. This change is mainly related to a decrease in diastolic velocity integrals.ConclusionThe proposed IFI provides information on the direction and, indirectly, on the volume of blood flow through the fetal aortic isthmus. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Use of three‐dimensional ultrasound imaging in the diagnosis of prenatal‐onset skeletal dysplasias
Authors: Krakow D. , Williams J. , Poehl M. , Rimoin D. L. , Platt L. D. 
Published: May 2003

AbstractObjectiveRecognition of prenatal‐onset skeletal dysplasias has improved with advances in ultrasound imaging. Skeletal abnormalities can be recognized by two‐dimensional (2D) ultrasound, but generating a precise diagnosis can be challenging. We aimed to determine whether three‐dimensional (3D) imaging conferred any advantages over 2D imaging in these cases.MethodsWe studied five women with fetuses of 16–28 gestational weeks referred for abnormal ultrasound skeletal findings. First 2D and then 3D sonography was performed and the results compared.ResultsThe pregnancies resulted in the following skeletal dysplasias: thanatophoric dysplasia, achondrogenesis II/hypochondrogenesis, achondroplasia, chondrodysplasia punctata (rhizomelic form) and Apert's syndrome. For all five fetuses, the correct diagnosis was made in the prenatal period by analysis of the 2D images. In each case the 3D images confirmed the preliminary diagnosis and for many findings it improved the visualization of the abnormalities.ConclusionThe 3D imaging had advantages over the 2D imaging when it came to evaluation of facial dysmorphism, relative proportion of the appendicular skeletal elements and the hands and feet. Most importantly, the patient and referring physician appreciated the 3D images of the abnormal findings more readily which aided in counseling and management of the pregnancy. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
La question de la rationalité: entre sociologie et économie
Authors: BRONNER GÉRALD 
Published: May 2003

[Lt ] Plus la construction typifiée est anonyme, plus elle est détachée
de l'unicité de l'individu en cause et moins les aspects de sa personnalité
et du modèle de son comportement entrent dans la typification en tant que pertinents pour
le but qu'on se propose, raison pour laquelle le type a été construit [Gt ]Alfred SchutzAttempts have been made to bring economics and sociology together, in particular when they are concerned with the modelling of decision-making and human rationality. However, an enduring epistemological obstacle remains: that of the classical distinction between raison d'être and raison de connaître. This paper examines some of the conceptual and practical problems raised by the nomological aim of econometrics.
Rumen function and digestion parameters associated with differences between sheep in methane emissions when fed chaffed lucerne hay
Authors: PINARES-PATIÑO C. S. , ULYATT M. J. , LASSEY K. R. , BARRY T. N. , HOLMES C. W. 
Published: May 2003

An indoor experiment involving 10 rumen-cannulated Romney sheep was conducted in May and June 1998 at AgResearch Grasslands, Palmerston North, New Zealand, under restricted feeding conditions, in order to test the hypothesis that animal factors, in particular rumen fractional outflow rate (FOR) and rumen volume, have an influence on the between-sheep variation in methane (CH4) emission. Sheep were fed 2-hourly on chaffed lucerne hay. Following an acclimatization period of 21 days, the experiment lasted 16 days. Energy and nitrogen (N) balances were measured on days 1–6. Cr-EDTA marker was continuously infused into the rumen from day 9 to 16, and rumen contents emptied and sampled on days 13 and 16. Particulate and fluid FOR were estimated using feed lignin and Cr-EDTA, respectively. Daily CH4 production was measured by the sulphur hexafluoride tracer technique on days 2, 5, 6, 12 and 15 of the experiment.CH4 production (g/day) was positively correlated with the pool size of organic matter (OM) in the rumen (OM pool, g) (r=0·84, P=0·002), OM intake (OMI, g/day) (r=0·67, P=0·04), and the rumen fill (g, wet digesta) (r=0·76, P=0·01). Multiple regression analysis showed that CH4 production was best predicted (R2=0·88) as a function of OM pool and the molar % of butyrate; however, OM pool alone accounted for a large proportion (R2=0·71) of the variation in CH4 production.CH4 yield (% gross energy intake, % GEI) was negatively correlated with the particulate FOR (%/h) (r=−0·75, P=0·01) and buffering capacity of rumen fluid (mmol HCl) (r=−0·72, P=0·02), but positively correlated with the digestibility of cellulose (r=0·66, P=0·04). Multiple regression analysis showed that CH4 yield was best predicted as a function of particulate FOR, OMI (g/kg liveweight0·75) and the molar % of butyrate (R2=0·88). Particulate FOR alone explained a large proportion (R2=0·57) of the variation in CH4 yield. Particulate FOR was negatively correlated with rumen fill (r=−0·69, P=0·03) and digestibility of cellulose (r=−0·65, P=0·04).These results suggest that sheep with lower rumen particulate FOR (i.e. longer rumen retention times) had larger rumen fills and higher fibre digestibilities and CH4 yields. If rumen particulate FOR is to be used as a tool for CH4 mitigation, the repeatability of its relationship to CH4 emission must be assessed, preferably under grazing conditions.