bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanism and kinetics of emulsion copolymerization of vinylidene chloride—Critical conversion at the end of interval 2 and rate of polymerization
Authors: Yu Zaizhang , Jia Hongbing , Li Bogeng , Li Baofang
Published: April 2007

In this paper, the change of vapour pressure in the emulsion copolymerization of vinylidene chloride (VDC) was determined. It was observed that the vapour pressure drops at conversion about 60% when VDC/comonomer = 90/10 (wt). The types of emulsifier, concentrations of emulsifier and initiator, temperature do not effect these conversion values significantly. According to the principle of phase equilibrium, that the critical conversion at the end of Interval 2 in the emulsion copolymerization of VDC is about 60% was suggested. The effects of types of emulsifier, concentrations of emulsifier and initiator, temperature, types and concentrations of comonomer on rate of copolymerization were also studied. It was found that the different types of comonomer will have no great effect on the copolymerization rate and intrinsic viscosity of a VDC copolymer. And a common route and recipe can be adopted for producing different grades of PVDC latex.
Laser photoacoustic and photothermal spectroscopies as novel characterization methods for microparticles
Authors: Kitamori Takehiko , Sawada Tsuguo
Published: April 2007

Photoacoustic and photothermal spectroscopy methods can be effectively applied to the characterization of single microparticles. As the optical beam deflection method, in which a thermal wave generated by non‐radiative transition is detected by deflection of a probe beam, is sensitive for a single microparticle, and is a remote‐measurement method without using a cell, it is suitable for nondestructive characterization of microparticles. This method was applied to determination of chemical species adsorbed on a single microparticle, and spectral differences between leukemia and normal white blood corpuscles could be obtained. A more violent photothermal conversion phenomenon of a particle, laser breakdown and accompanying plasma and acoustic emission, was applied to individual detection and analysis of ultrafine particles in liquids. Laser‐like nonlinear emission from the plasma was observed.
Production of micron‐size monodisperse polymer particles by seeded polymerization utilizing dynamic swelling method with cooling process
Authors: Okubo Masayoshi , Shiozaki Masaya
Published: April 2007

Monodisperse polystyrene particles (6.6 μm diameter) were produced by seeded polymerization utilizing the dynamic swelling method with cooling process as follows. Monodisperse polystyrene seed particles (1.8 μm diameter) were dispersed in ethanol/water (3/4 w/w) medium containing styrene monomer, benzoyl peroxide as initiator and poly(vinyl alcohol) as stabilizer at 65d̀C. By lowering the temperature to −5d̀C at a speed of −1d̀C/min the polystyrene seed particles were swollen from 1.8 to 7.7 μm by the absorption of styrene monomer, keeping the high monodispersity. An appropriate amount of water was then added to the dispersion at −5d̀C to depress the redissolution of styrene from the swollen particles into the medium. By elevating the temperature the seeded polymerization was carried out at 70d̀C. The production of submicron‐size polystyrene new particles as a by‐product was depressed by the addition of NaNO2 to the medium.
Soapfree emulsion polymerization of methyl methacrylate in the presence of CaSO3
Authors: Lee Chia‐Fen , Chiu Wen‐Yen
Published: April 2007

In the soapfree emulsion polymerization of a methyl methacrylate‐K2S2O8‐CaSO3‐H2O system, the polymerization rate, average molecular weight of polymer, particle size and particle concentration would vary with the concentration of CaSO3.

It was shown that when the concentration of CaSO3 was well below the saturation concentration (3 × 10−4mol/litre H2O), the polymerization rate was higher than that of the system not containing CaSO3. On the other hand, when the concentration of CaSO3 was above the saturation concentration, the polymerization rate at the latter stage was lower than that of the system not containing CaSO3 within our experimental conditions.

The molecular weight of polymer was measured by Gel Permeation Chromatography (GPC). It decreased initially and then increased due to the gel effect over the entire course of polymerization. The size of the polymer particles was measured by both photo correlation spectroscopy (PCS) and transmission electron microscopy (TEM), The reaction mechanism was studied according to the above observation. The mechanical property of poly(methyl methacrylate)‐CaSO3 composite obtained from soapfree emulsion polymerization was tested and compared with that obtained from mechanical blending.
Particle nucleation in emulsion copolymerization containing multifunctional monomers
Authors: Nomura M. , Fujita K.
Published: April 2007

Characteristic features of particle nucleation and growth in the emulsion copolymerization of styrene and multifunctional monomers such as ethylene glycol dimethacrylate and divinylbenzene were investigated. It was found that in these emulsion copolymerization systems the rate of polymerization per particle decreased drastically with an increase in the content of the multifunctional monomer in the initial monomer feed, and the number of polymer particles produced, on the other hand, increased corresponding to the decrease in the rate of polymerization per particle. The increase in the number of polymer particles produced was explained on the basis of Smith‐Ewart theory, which predicts that the number of polymer particles produced would increase inversely proportional to the 0.4 power of the volumetric growth rate per particle, that is the rate of polymerization per particle during the interval of particle formation (Interval I). It was pointed out that the decrease in the rate of polymerization per particle in Interval I would be due mainly to a decrease in the monomer concentration in the polymer particles which was caused by crosslinking networks of the resultant polymer.
Polymerization of micelle‐forming monomers: Mechanistic study and characterization of the systems before and after polymerization
Authors: Cochin D. , Zana R. , Candau F.
Published: April 2007

Cationic surfactants bearing a polymerizable styryl headgroup and a variable alkyl chain with 8–16 carbon atoms have been synthesized. Their aqueous solutions have been characterized by the surfactant critical micellar concentration (CMC) and aggregation number using electrical conductivity, spectrofluorimetry and time‐resolved fluorescence quenching. The photoinitiated polymerization of these surfactants in the micellar state led to stable and transparent or slightly bluish systems. The kinetics of polymerization were measured by dilatometry and were found to be close to those obtained for styrene emulsion polymerization. A mechanism of polymerization is proposed and discussed in terms of micellar dynamics. The polymerized systems, p(Cn‐STY), and the recovered polymers were characterized by means of several complementary techniques. The polymers have high molecular weights (3 × 105‐3 × 106), which indicates that the initial micellar structure is not preserved upon polymerization. The structure of the polymerized systems depends on the alkyl chain length of the surfactant. The p(C16‐STY) systems exhibit a structure similar to that of a polysoap with intramolecular hydrophobic microdomains whereas the p(C8‐STY) systems behave like classical polyelectrolytes.
Effect of crosslinked core on minimum film formation temperature and morphology of composite microspheres
Authors: Omi Shinzo , Kohmoto Takeyoshi , Iso Mamoru
Published: April 2007

Effect of crosslinking on minimum film formation temperature (MFT) and particle morphology was investigated using the latices composed by the combination of crosslinked soft core‐hard shell. n‐Butyl acrylate (nBA) and ethylene glycol dimethacrylate (EGDMA) were used to prepare crosslinked rubber with methylmethacrylate (MMA) or styrene (ST) as a hard plastic component. Ordinary batch (flooded with secondary monomer) and semicontinuous (starved feed) operations were employed to compare the thermal properties of composite latices resulting from the different mode of secondary polymerization. As the degree of crosslinking increases, MFT of the latices obtained by batch operation became higher than those by semibatch operation. Observation of microtomed sections of particles stained with RuO4 did not reveal much difference in particle morphologies between the two operations. There was a definite relationship between MFT and molecular weight of THF soluble fraction of composite polymers regardless the mode of operation.
Characteristics of water‐absorbent polymer emulsions
Authors: Watanabe Naotaka , Hosoya Yoshio , Tamura Akira , Kosuge Hiroshi
Published: April 2007

Water‐in‐Oil (W/O) and Oil‐in‐Water (O/W) type water absorbent polymer emulsions were studied using two different polymerization methods. W/O type water absorbent polymer emulsions were prepared by the inverse emulsion polymerization of ammonium acrylate (AA), the quaternized salt of dimethyl‐aminoethyl methacrylate (DMQ) and acrylamide (AM) with N,N‐methylene‐bisacrylamide (MBA) as a crosslinker. A pH sensitive water absorbent polymer emulsion was prepared by the conventional emulsion polymerization of diethyl‐aminoethyl methacrylate (DEAEMA) with ethylene glycol dimethacrylate (EGDMA) as a crosslinker.

It was confirmed that the water absorption capacity of crosslinked polymers in inverse emulsion was controlled by crosslink density and dissociative charge density, and the crosslinked polyDEAEMA particles had a phase transition property of swelling and shrinking with pH. The dispersions of these water swollen crosslinked polymer particles exhibited an increase in viscosity and thixotropic fluidity.
1H magnetic relaxation times in isotactic polypropylene crystallized at high temperature. Effect of molecular weight
Authors: Tanaka Hiroshi , Inoue Yoshinori
Published: April 2007

The temperature dependence of 1H spin‐lattice, T1(H), and spin‐spin, T2(H), relaxation times of isotactic polypropylene with relatively low molecular weight, M̄w = 1.95 × 105, and ultra‐high molecular weight, M̄w = 1.78 × 106, crystallized at high temperature (155° C) for a long time (200 h), was measured with a broad line pulse spectrometer. T1(H) for the ultra‐high molecular weight sample is shorter than that for the low molecular weight sample, while T2(H) for the ultra‐high molecular weight sample is longer than that for the low molecular weight sample. From the analysis of free induction decay (FID), three components of T2(H), i.e. T2c(H), T2m(H) and T2a(H), were obtained. These relaxation times are associated with the crystalline, intermediate and amorphous regions, respectively. Here the intermediate regions are the regions in which chain molecules have intermediate mobility between that of crystalline and amorphous regions. A decrease in signal intensity of methylene, methine and methyl carbons was measured as a function of delay time following a 90° pulse before cross‐polarization. From the slope of a log (intensity) versus t2 plot a relaxation time associated with rigid regions of proton nuclei, T2r(H), was obtained, where the rigid regions are the regions in which cross‐polarization occurs easily. The value of T2r(H) lies between that of T2c(H) and T2m(H), indicating that the intermediate regions act as the rigid regions so far as cross‐polarization is concerned.
Synthesis and thermal transition of side‐chain liquid crystalline polyoxetanes having laterally attached mesogenic group
Authors: Kawakami Yusuke , Takahashi Koji , Nishiguchi Shigeo , Toida Kozo
Published: April 2007

Side‐chain liquid crystalline polymers with laterally attached mesogenic group were synthesized. Polymers having polyoxetane main chain were obtained by cationic polymerization, and with polymethacrylate main chain by radical polymerization. Some of the polymers showed nematic phase, and polyoxetanes having mesogen with electron‐withdrawing and electron‐donating groups in the molecule showed a little more discrete mesophase.
Studies on the hydrogenation of alkenes and alkynes using polymer coated silica‐Pd catalysts
Authors: Mathew Joice P. , Srinivasan M.
Published: April 2007

Palladium complexes of crosslinked polyacrylamide and poly‐N‐vinylimidazole coated on silica gel have been prepared and used as hydrogenation catalysts for alkenes, dienes and alkynes under ambient conditions. The characterisation of the catalysts, the kinetic and mechanistic aspects of the hydrogenation of a few substrates, the effect of temperature, selectivity and the recycling efficiency of the catalysts are presented. A comparison of their activity is made with other silica supported and silica free polymer‐Pd catalysts.
Kinetic behaviour of permeability of polyethylene membrane to chloroform vapour
Authors: Bajpai U. D. N. , Bajpai A. K.
Published: April 2007

The permeability behaviour of thin polyethylene membrane to chloroform vapour has been studied from the kinetic point of view between 15 and 35 ± 0.5°C. It was found that in the constant rate region, the permeability obeys second‐order reaction kinetics. The activation energy and entropy of activation of the permeability process were found to be 13.81 kcal/deg/mol and 33.74 eu, respectively. The physical nature of the membrane was found to affect the permeability process.
Effecters on human placental alkaline phosphatase activity
Authors: Roig M. G. , Ghaïs N. I. , Burguillo F. J. , Cachaza J. M. , Kennedy J. F.
Published: April 2007

A kinetic study has been carried out on the effects of enzyme concentration, protein (human serum albumin) concentration and ionic strength (inorganic and organic sodium salts) on the activity of human placental alkaline phosphatase in solution. The activity is depressed by serum albumin, and the corresponding complex of the protein with the substrate, decreasing its concentration available for catalysis, is responsible for an effect similar to competitive inhibition of the alkaline phosphatase activity. Activating and inhibiting effects were found for inorganic anions, respectively.
Monoalkylitaconates–vinylpyrrolidone copolymers. 2. Reactivity ratios and viscometric behaviour in dilute solutions
Authors: Radić Deodato , Opazo Alejandra , Vildósola Gonzalo , Gargallo Ligia
Published: April 2007

Copolymerization of mono‐n‐decyl and mono‐n‐decyl and mono‐n‐dodecyl itaconate with vinylpyrrolidone (MOI‐VP, MDI‐VP and MDoI‐VP) was carried out using AIBN as initiator. The monomer reactivity ratios were determined by the Fineman‐Ross and Kelen‐Tüdös methods. Values of r1 and r2 were found to be less than unity for MOI‐VP, MDI‐VP and MDoI‐VP, corresponding to random copolymers with some tendency to alternance. Copolymers of various compositions were studied in solution, and Mark‐Houwink‐Kuhn‐Sakurada relationships were established in ethanol for MOI‐VP and MDI‐VP copolymers, and in 1‐propanol for MDoI‐VP. The rigidity factors s̀ and the characteristic ratio C∞ were obtained from Kθ values determined by using the Stockmayer‐Fixman relation. In all the copolymers the introduction of vinylpyrrolidone units produces flexibility of the polymer chain relative to the poly(monoitaconate) homopolymers, and the solution properties of these copolymers can be described by assuming a random coil model instead of a rigid rod or wormlike model as in poly(monoitaconates).
Optical activity measurements on solids. 3. Non‐optically active synthetic polymers
Authors: Xi Fu , Bartus Jan , Vogl Otto
Published: April 2007

Measurements of the non‐existence of optical activity in suspensions of synthetic optically inactive polymer powders were made to evaluate the limitation of our measurement technique. A particle size of less than 150μm was necessary to obtain accurate measurements. A high degree of crystallinity interfered with the measurements and gave erratic results. In all cases, for various types of commonly used polymers, the optical activity measurements with a zero value for optical rotation demonstrated that reliable measurements could be made with an accuracy of about ±3%.
Solution properties of poly(fluorostyrene‐co‐chlorostyrene) copolymers. II. High‐performance gel permeation chromatography
Authors: Segudovic Nikola , Vukovic Radivoje , Kuresevic Vjera , Karas Frank E. , Macknight William J.
Published: April 2007

The molecular weight distribution of random, unfractionated copolymers of ortho‐ and para‐fluorostyrene and ortho‐ and para‐chlorostyrene were determined. Good agreement was obtained between average molecular weights determined by absolute methods (light scattering and osmometry) and those determined by high‐performance gel permeation chromatography and a universal calibration procedure. The measurements were carried out in tetrahydrofuran at room temperature by using the following relationships between intrinsic viscosity [η] and weight‐average molecular weight M̄w.
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Thermal properties of a tough, new semicrystalline polyimide
Authors: Chalmers Tammy M. , Zhang Anqiu , Shen Dexing , Lien Shawn Hsun‐Shan , Tso Chung C. , Gabori Patricia A. , Harris Frank W. , Cheng Stephen Z. D.
Published: April 2007

Thermal properties of a new semicrystalline polyimide synthesized from 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA) and 2,2‐dimethyl‐1,3‐(4‐aminophenoxy)propane (DMDA) have been studied. Heat capacities in the solid and liquid states of BTDA‐DMDA have been measured. The heat capacity increase at the glass transition temperature (Tg = 230°C) is 145 J/°Cmol for amorphous BTDA‐DMDA. The equilibrium heat of fusion of the BTDA‐DMDA crystals has been obtained using wide‐angle X‐ray diffraction and differential scanning calorimetry measurements, and is 75.8 kj/mol. Based on the information on crystallinity and the heat capacity increase at Tg, a rigid amorphous fraction is identified in semicrystalline BTDA‐DMDA samples, which represents an interfacial region between the crystalline and amorphous states. In particular, this fraction increases with the crystallinity of the sample, which should be associated with crystal sizes, and therefore with crystal morphology. It has also been found that this polymer has a high‐temperature crystal phase upon annealing above its original melting temperature. The thermal degradation activation energies of BTDA‐DMDA in nitrogen and air are determined to be 154 and 150kJ/mol, respectively.
Properties of epoxy resin cured by phenol novolac/4‐hydroxyphenylmaleimide polymer blend hardeners
Authors: Matsumoto Akihiro , Hasegawa Kiichi , Fukuda Akinori , Pae Jong‐Se
Published: April 2007

Phenol novolac/4‐hydroxyphenylmaleimide (HPMI) homopolymer (PHPMI) blends or phenol novolac/HPMI‐styrene copolymer (HPMI‐St) blends were used as the hardener of epoxy resins. Curing behaviour of the above systems and thermal and mechanical properties of the cured epoxy resins were studied. It was not necessary to use a curing accelerator for this system because PHPMI or HPMI‐St had an accelerating effect on the curing reaction. Curing behaviour was investigated by measurement of gelation time(JIS K 6910) and differential scanning calorimetry thermogram (JIS K 7122). Test pieces made from neat resins and from reinforced resins with glass fibre or fused silica were evaluated in terms of thermal and mechanical properties, respectively. It was found that the heat resistance and the mechanical properties improved with increase of PHPMI or HPMI‐St content in the hardener.
Studies on thermal stability and behaviour of polyacetal and thermoplastic polyurethane elastomer blends
Authors: Kumar G. , Mahesh L. , Neelakantan N. R. , Subramanian N.
Published: April 2007

The influence of thermoplastic polyurethane (TPU) elastomer on the rigidity of polyacetal (polyoxymethylene, POM) was studied by determining heat deflection temperature (HDT). The higher the content of TPU in the POM/TPU blend, the lower the HDT of the blend, as would be expected. A comparative study of the recycle capability of POM and the blends was carried out by measuring melt flow index (MFI) on each successive extrusion. Stress‐strain behaviour of the virgin material and that obtained after fourth‐time extrusion was analysed for POM and the blends. The effect of γ‐radiation on the mechanical behaviour of the blends was investigated. The kinetics of thermal degradation of POM, TPU and their blends was studied. The kinetic parameters, viz. activation energy and the order of reaction, were established. The values of the activation energy of the blends were found to be higher than those of the POM and TPU, indicating improved stability of the resultant blends.
Distribution of surfactants in poly(2‐ethyl hexyl methacrylate) latexes
Authors: Kientz E. , Danicher L. , Lambla M. , Holl Y.
Published: April 2007

The adsorption characteristics of four surfactants were studied: sodium dodecyl sulfate (SDS), hexadecyl trimethylammonium bromide (HTAB), hexadecyl pyridinium chloride (HPCI) and ethoxylated nonyl phenol containing 10 segments of ethylene oxide (NP10) in poly(2‐ethyl hexyl methacrylate) (P2EHMA) latexes. Areas per molecule at the particle‐water interface (at the critical micellar concentration) were determined as well as the compacities of the adsorbed layers and the Helmholtz free energies of adsorption (Δμ°). The order of increasing Δμ° is NP10<HTAB, HPCI<SDS. This later result provides valuable information on the rate of surfactant desorption during the latex film formation. The repartition of the surfactant in the latex, mainly between the aqueous phase and the particle‐water interface, was quantitatively determined. The main results presented here will be used in a subsequent article dealing with the interpretation of the distribution of surfactants in latex films.
High‐frequency oscillation (HFO) prevents activation of NF‐κB found with conventional mechanical ventilation (CMV) in surfactant‐depleted rabbit lung
Authors: Waragai Aki , Yamashita Hiroko , Hosoi Kenichiro , Hoshina Hiroaki , Noda Eri , Yan Kunimasa , Kawano Toshio
Published: April 2007

High‐frequency oscillation (HFO) has been recognized as an effective ventilatory strategy to minimize lung injury during respiratory support. Conventional mechanical ventilation (CMV) compared with HFO was shown to result in an increased number of PMNs and inflammatory cytokines in the lung lavage fluid. However how mechanical forces can be sensed by cells and converted into biochemical signals for intracellular signal transduction is still unknown. In this current study, we sought to determine whether the activation of Nuclear factor‐kappa B (NF‐κB) might be involved in the lung injury caused by CMV. Surfactant‐depleted Japanese white rabbits received 1‐ or 4‐hr CMV or 1‐ or 4‐hr HFO. Then, activation of NF‐κB in the lungs was assessed by conducting electrophoretic mobility shift assays (EMSA). In the experiment with whole lungs, NF‐κB activity was much higher in the 4‐hr CMV lungs than in the 4‐hr HFO lungs. To clarify the origin of the cells in which NF‐κB was activated, we did a second lung lavage at the end of ventilation and washed out the cells that had infiltrated the alveoli. The levels of NF‐κB activity were the similar in the lungs of 4‐hr HFO rabbits and in those of 4‐hr CMV ones. On the other hand, NF‐κB activity was much higher in the 4‐hr CMV lungs than in the 4‐hr HFO lungs in the experiment with the lung lavage fluid cells. These results show that the increase in NF‐κB activity in the lungs of 4‐hr CMV rabbits was due mainly to the cells that had infiltrated the alveoli. Pediatr Pulmonol. 2007; 42:440–445. © 2007 Wiley‐Liss, Inc.
Accuracy of binding mode prediction with a cascadic stochastic tunneling method
Authors: Fischer Bernhard , Basili Serena , Merlitz Holger , Wenzel Wolfgang
Published: April 2007

We investigate the accuracy of the binding modes predicted for 83 complexes of the high‐resolution subset of the ASTEX/CCDC receptor‐ligand database using the atomistic FlexScreen approach with a simple forcefield‐based scoring function. The median RMS deviation between experimental and predicted binding mode was just 0.83 Å. Over 80% of the ligands dock within 2 Å of the experimental binding mode, for 60 complexes the docking protocol locates the correct binding mode in all of ten independent simulations. Most docking failures arise because (a) the experimental structure clashed in our forcefield and is thus unattainable in the docking process or (b) because the ligand is stabilized by crystal water. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Robot Assisted Laparoscopic Pyeloplasty: a review of the current status
Authors: Shah Ketul K. , Louie Michael , Thaly Rahul K. , Patel Vipul R.
Published: April 2007

Background

Over the last decade minimally invasive endourologic and laparoscopic techniques have become the first line therapies for primary UPJ obstruction. Robotic assisted laparoscopic pyeloplasty for the correction of ureteropelvic junction has achieved outcomes comparable to those of open and laparoscopic techniques. We present a comprehensive review of the current literature of robotic assisted pyeloplasty.

Methods

We performed a systemic review of all the current literature examining demographic data, intra operative parameters and post‐operative outcomes.

Results

In most published series in the literature, the operative time ranges from 122 to 300 minutes and the operative time ranges from 27 to 77 ml. Most series considers subjective improvement in the symptoms and improved drainage on post‐operative diuretic renal scan as the measures of success. The reported success rates vary from 89 to 100%.

Conclusion

Robotic pyeloplasty is a feasible alternative to laparoscopic pyeloplasty. Short‐term results indicate equivalent outcomes with the laparoscopic procedure. Long‐term studies are still needed to compare robotic and open pyeloplasty outcomes, and to define the role of robotic pyeloplasty in a cost prohibitive health care system. Copyright © 2007 John Wiley & Sons, Ltd.
Regular Dislocation Networks in Silicon as a Tool for Nanostructure Devices used in Optics, Biology, and Electronics
Authors: Kittler M. , Yu X. , Mchedlidze T. , Arguirov T. , Vyvenko O. F. , Seifert W. , Reiche M. , Wilhelm T. , Seibt M. , Voß O. , Wolff A. , Fritzsche W.
Published: April 2007

Well‐controlled fabrication of dislocation networks in Si using direct wafer bonding opens broad possibilities for nanotechnology applications. Concepts of dislocation‐network‐based light emitters, manipulators of biomolecules, gettering and insulating layers, and three‐dimensional buried conductive channels are presented and discussed. A prototype of a Si‐based light emitter working at a wavelength of about 1.5 μm with an efficiency potential estimated at 1 % is demonstrated.
Detection of chromosomal abnormalities, congenital abnormalities and transfusion syndrome in twins
Authors: Sperling L. , Kiil C. , Larsen L. U. , Brocks V. , Wojdemann K. R. , Qvist I. , Schwartz M. , Jørgensen C. , Espersen G. , Skajaa K. , Bang J. , Tabor A.
Published: April 2007

Objective

To evaluate the outcome of screening for structural malformations in twins and the outcome of screening for twin–twin transfusion syndrome (TTTS) among monochorionic twins through a number of ultrasound scans from 12 weeks' gestation.

Methods

Enrolled into this prospective multicenter observational study were women with twin pregnancies diagnosed before 14 + 6 gestational weeks. The monochorionic pregnancies were scanned every second week until 23 weeks in order to rule out early TTTS. All pregnancies had an anomaly scan in week 19 and fetal echocardiography in week 21 that was performed by specialists in fetal echocardiography. Zygosity was determined by DNA analysis in all twin pairs with the same sex.

Results

Among the 495 pregnancies the prenatal detection rate for severe structural abnormalities including chromosomal aneuploidies was 83% by the combination of a first‐trimester nuchal translucency scan and the anomaly scan in week 19. The incidence of severe structural abnormalities was 2.6% and two‐thirds of these anomalies were cardiac. There was no significant difference between the incidence in monozygotic and dizygotic twins, nor between twins conceived naturally or those conceived by assisted reproduction. The incidence of TTTS was 23% from 12 weeks until delivery, and all those monochorionic twin pregnancies that miscarried had signs of TTTS.

Conclusion

Twin pregnancies have an increased risk of congenital malformations and one out of four monochorionic pregnancies develops TTTS. Ultrasound screening to assess chorionicity and follow‐up of monochorionic pregnancies to detect signs of TTTS, as well as malformation screening, are therefore essential in the antenatal care of twin pregnancies. Copyright © 2007 ISUOG. Published by John Wiley & Sons, Ltd.
Transvaginal ultrasound measurement of cervical length and efficacy of misoprostol in first‐trimester pregnancy failure
Authors: Agostini A. , Capelle M. , Ronda I. , Bretelle F. , Cravello L. , Blanc B.
Published: April 2007

Objective

The aim of this study was to assess the role of cervical length measurement in predicting successful treatment, by misoprostol administration, of early (first‐trimester) pregnancy failure.

Method

A prospective study was conducted of all patients who agreed to medical treatment of pregnancy failure. Cervical length and other sonographic variables were measured using pelvic ultrasound before medical treatment began. Measurements were compared between the group with successful medical treatment and the group in whom treatment failed.

Results

In 125 women included in the study, the success rate of misoprostol treatment was 64.8%. There were no significant differences between the groups with successful and failed treatment for cervical length (29.9 ± 9.3 vs. 30.4 ± 6.8 mm, P = 0.75), distance between gestational sac and ‘virtual’ cervical internal os (23.9 ± 13 vs. 26.6 ± 13 mm, P = 0.26), crown–rump length (8.7 ± 9.7 vs. 6.7 ± 8.6 mm, P = 0.25), or gestational sac diameter (31.3 ± 14 vs. 30.1 ± 15 mm, P = 0.73).

Conclusion

Cervical length does not predict the success of misoprostol treatment of first‐trimester pregnancy failure. Copyright © 2007 ISUOG. Published by John Wiley & Sons, Ltd.
Sensitive determination of terazosin by x‐ray fluorescence spectrometry based on the formation of ion‐pair associates with zinc thiocyanate
Authors: Silva Raúl A. , Masi Adriana N.
Published: April 2007

A new, simple and precise indirect method for the determination of terazosin through x‐ray fluorescence (XRF) is proposed. The method is based on the precipitation of an ion‐associate complex formed between terazosin and [Zn(SCN)4]2− and the formation of a thin film on a membrane filter. The optimum conditions for ion‐associate complex formation, such as pH, ionic strength, shaking time and stoichiometry of the complex, were studied. The complex was retained on the membrane filter, and the Zn Kα line was measured by XRF. The method presents the advantages of the separation of the drug from the matrix (excipients), the preconcentration of Zn, producing enhancement of XRF intensity though increased sensitivity, and the elimination of the matrix effects due to the thin film obtained. The lowest detection limit was 0.732 µg ml−1. The validation studies were realized by the related applications and the results were evaluated statistically. The method was successfully applied to terazosin determination in tablets or in bulk. Copyright © 2007 John Wiley & Sons, Ltd.
7201 Carcinoids: Increasing Incidence Overall and Disproportionate Mortality in the Elderly
Authors: Perez Eduardo A. , Koniaris Leonidas G. , Snell Sarah E. , Gutierrez Juan C. , Sumner William E. , Lee David J. , Hodgson Nicole C. , Livingstone Alan S. , Franceschi Dido
Published: April 2007

Introduction

The aim of the study was to determine outcomes for respiratory and gastrointestinal carcinoid tumors utilizing a large cancer registry.

Methods

Cases of respiratory and gastrointestinal carcinoid from the Florida Cancer Data System (FCDS) from 1981 to 2001 were reviewed. Descriptive statistics, age‐adjusted tumor incidence, and survival rates were determined.

Results

A total of 7201 cases of malignant carcinoid were identified. Pulmonary and gastrointestinal carcinoid tumors comprised 82% of all carcinoids encountered. The mean age was 64.4 ± 0.15 years. Stratified by location, there were 3000 (51.4%) foregut carcinoids (including those found in the respiratory tree—2325 in the lung), 2130 (36.5%) midgut carcinoids, and 712 (12.2%) hindgut carcinoids. Second, distinct malignancies were observed in 23% of cases. The total age‐adjusted incidence rate has increased from 0.62 per 100,000 in 1980 to 5.17 per 100,000 in 2000. Overall median survival was 21.97 months. The median survival was 19.0 months for foregut carcinoids (excluding those arising in the respiratory tract); 33.9 months for midgut tumors; and 22.7 months for hindgut carcinoids. There was a statistically significant better survival for those with midgut tumors than for those in the other groups (P < 0.001). Age < 60 years, white race, and female sex were all associated with better survival (P < 0.01).

Conclusions

The incidence of pulmonary and gastrointestinal carcinoids has dramatically increased since 1981. Tumor location and age ≥ 60 years are the strongest predictors of mortality.
Portal Venous Gas Detected on Computed Tomography in Emergency Situations: Surgery Is Still Necessary
Authors: Monneuse Olivier , Pilleul Frank , Barth Xavier , Gruner Laurent , Allaouchiche Bernard , Valette Pierre‐Jean , Tissot E.
Published: April 2007

Background

Portal venous gas (PVG) has been reported to be associated with lethal surgical diagnosis. Recent studies tend to confirm the clinical significance of gas in the portal vein; however, some patients are managed without surgical treatment. The aim of this study was to assess both the diagnoses and the treatment of patients with PVG in an emergency surgical setting.

Materials and methods

We performed a retrospective chart review of 15 patients with PVG in the emergency setting detected by computed tomography (CT) between July 1999 and July 2004. Characteristics assessed included age, sex, clinical presentation, first CT diagnosis of both PVG and the underlying pathology, American Society of Anesthesiologists (ASA) score, surgical findings, final clinical diagnosis, duration of hospitalization, and evolution of the illness/mortality. All patients were examined one month after operation.

Results

This series of 5 women and 10 men ranged in age from 38 to 90 years at the time they underwent emergency surgical treatment. The mean preoperative ASA score was 4.20. Computed tomography diagnosed the underlying pathology in all cases: bowel obstruction (4 cases), bowel necrosis (9 cases), and diffuse peritonitis (2 cases). The mean length of hospital stay was 12.4 days. The mortality rate was 46.6%; (7 patients).

Conclusions

A wide range of pathologies can generate PVG. Computed tomography can detect both the presence of gas and the underlying pathology. In emergency situations, all the diagnosed causal pathologies required a surgical procedure without delay. We report that the prognosis was related to the pathology itself and was not influenced by the presence of PVG.
Deprivation of pantothenic acid elicits a movement disorder and azoospermia in a mouse model of pantothenate kinase‐associated neurodegeneration
Authors: Kuo Y. M. , Hayflick S. J. , Gitschier J.
Published: April 2007

We asked whether a movement disorder could be elicited by deprivation of pantothenic acid (PA; vitamin B5), the substrate for the enzyme pantothenate kinase 2 (PANK2), which is deficient in the inherited neurological disorder PKAN (pantothenate kinase‐associated neurodegeneration formerly called Hallervorden–Spatz syndrome). This study was undertaken because mice made null for Pank2 failed to show the neurological manifestations of the human disease. Wild‐type and Pank2 mutant mice were fed pantothenic acid‐deficient diets and were monitored for general health, fertility and movement compared with animals on control diets over time. Mice of both genotypes on PA‐deficient diets exhibited poor grooming, greying of fur and decreased body weight. With PA deprivation, wild‐type mice manifested azoospermia (a phenotype also seen in Pank2 mice) as well as a movement disorder with a low‐lying pelvis and slow steps. Rear limbs appeared to drag and occasionally extended into unnatural postures for 16–17s duration, possibly indicative of dystonia. Movement disruption probably also occurs in PA‐deprived Pank2 mutant mice, but they died precipitously before undergoing detailed analysis. Remarkably, restoration of dietary PA led to recovery of general health and grooming, weight gain, reversal of the movement disorder, and reappearance of mature sperm within 4 weeks. This study confirms the primacy of PA metabolism in the mechanism of disease in PKAN. PA deprivation provides a useful phenocopy for PKAN and allows us to test pharmacological and other interventional strategies in the treatment of this devastating disease.
Clinical Research in Practice: A Guide for the Bedside Scientist
Authors: Scherffius Jo Ann
Published: April 2007

Clinical Research in Practice: A Guide for the Bedside Scientist Janet Houser and Joanna Bokovoy, 2006, 277 pages, $42.95 softcover
On the effect of baryon loading in magnetized counterstreaming plasmas. I. Analytical investigation
Authors: TAUTZ R. C. , SAKAI J.-I.
Published: April 2007

Assuming a non-relativistic three species electron–positron–ion plasma, the counterstreaming instability is investigated for waves propagating parallel and perpendicular to a homogeneous background magnetic field. From the exact linear dispersion relations, it is shown analytically how the growth rates change with increasing baryon loading, revealing new characteristics that cannot be found either for an unmagnetized plasma involving three particle species or for a plasma with only two particle species.
HAUSDORFF DIMENSION OF SELF-SIMILAR SETS WITH OVERLAPS
Authors: NGAI SZE-MAN , WANG YANG
Published: April 2007

The notion of ‘finite type’ iterated function systems of contractive similitudes is introduced, and
a scheme for computing the exact Hausdorff dimension of their attractors in the absence of the open set
condition is described. This method extends a previous one by Lalley, and applies not only to the classes of
self-similar sets studied by Edgar, Lalley, Rao and Wen, and others, but also to some new classes that are
not covered by the previous ones.
The Conceptual Obstacles to Political Reform in Iran
Authors: Masroori Cyrus
Published: April 2007

This paper explores some of the basic ideological tenets of former Iranian President Muhammad Khatami, showing how they prevented him from realizing his reform agenda. Ideological inconsistencies and ambiguities exposed Khatami and his allies to criticism from both conservatives and radical reformers. Consequently, many Iranians who once voted for Khatami and his allies boycotted the presidential elections of 2005, paving the way for a conservative to succeed Khatami as president of Iran.
Teaching the Questions: Aristotle's Philosophical Pedagogy in the Nicomachean Ethics and the Politics
Authors: Salkever Stephen
Published: April 2007

It is widely acknowledged that the style of Plato's political philosophizing is radically different from the systems and doctrines approach established by Hobbes and confirmed and redirected by Kant. But what about Aristotle? Does he intend to produce systematic political theory in sharp contrast to Plato's question-centered dialectics? This essay argues that Aristotle's political science is equally as dialogical as Plato's. Taken together, the Nicomachean Ethics and the Politics form a single set of lectures, craftily organized to lead its immediate Greek audience (the equivalent of Socrates' interlocutors in Plato) deeply into the questions and problems that are Aristotle's theoretical basis for the paradigmatically human activities of practical reason (phronêsis) and thoughtful choice (prohairesis). He accomplishes this goal by allowing none of the answers he or his audience might propose to stand unchallenged, thus acting as another, albeit soberer, Socrates to his politically concerned audience then and, potentially, now.
Globalization and the Transformation of Work in Rural Brazil: Agribusiness, Rural Labor Unions, and Peasant Mobilization
Authors: Welch Cliff
Published: April 2007

This article examines recent Brazilian rural labor and agricultural history. It identifies three broad periods for analysis in the postwar era: the 1940s to 1960s, the 1960s to 1980s, and a third period that dates roughly from the promulgation of Brazil's new constitution in 1988 to the present. Using primary and secondary sources the article analyzes recent agrarian transformations associated with globalization, including the organized response of workers and farmers to the loss of millions farm livelihoods. It explains the rise of an autonomous peasant movement in the late twentieth century and describes the recent development of a polemic between a peasant vision of expanded family farming and the agricultural capitalist model promoted by powerful agribusiness interests.
A New World of Retail Supremacy: Supply Chains and Workers' Chains in the Age of Wal-Mart
Authors: Appelbaum Richard , Lichtenstein Nelson
Published: April 2007

In contrast to the mid-twentieth century era of transnational commerce, in which the US or European manufacturing multinationals played the leading role, twenty-first century globalization is increasingly structured by a set of retail-dominated supply chains, that of Wal-Mart first among them. This strategic shift in the locus of corporate power has arisen out of two conjoined phenomena: first, the logistical integration made possible and necessary by the revolution in information/transportation technology (bar codes, data storage, containerization, global communications), and second, the neoliberal transformation of the worldwide political economy, which in the US has facilitated the massive expansion of a low-wage, import dependent retail sector, while in coastal China it has generated a huge export-manufacturing boom. But the global supply chain linking Guangdong Province to Bentonville, Arkansas may well be an increasingly fragile one, because the proletarianization of tens of millions of Chinese peasants is unlikely to go smoothly, especially under conditions of authoritarian governance.
Global Processes and Local Lives: Guatemalan Women's Work and Gender Relations at Home and Abroad
Authors: Menjívar Cecilia
Published: April 2007

In this paper I address an important aspect of the link between the larger process of globalization and work. I focus on how globalization has affected the lives of Guatemalan women of different class backgrounds and ethnicities in Guatemala and in Los Angeles, through an examination of the link between paid work and household work. Data for this article come from eighty-six in-depth interviews with indigenous and ladina women and from ethnographic field work I conducted in Los Angeles and in two regions of Guatemala. There are certain aspects of earning an income among the women in this study that emerge in both contexts, perhaps due to the demands of contemporary capitalism on workers around the world. My observations indicate that whereas the experiences of women and femininities are played out in the context of global economic relations, they are experienced differently in diverse sites and within the same context by individuals of different class and ethnic backgrounds. Thus, experiences of globalization through work are very much localized; they are historically and culturally situated and interact with broader processes in dissimilar fashion.
Peshat and the Authority of Hazal in the Commentaries of Radak
Authors: Berger Yitzhak
Published: April 2007

In the study of medieval biblical interpretation, the tension between commentators' fidelity to rabbinic midrash and their independent quest for peshat continues to command serious attention. The place of the important Provençal exegete R. David Kimhִi (Radak, ca. 1160–ca. 1235) in the history of peshat commentary is of particular interest, influenced as he was by an especially wide range of traditions. On one hand, Radak's family, which was of Spanish origin, produced grammatical works and commentaries that exemplify the strict text-based approach of the Andalusian exegetes. Indeed, R. Abraham Ibn Ezra, the most prominent representative of this school, influenced Radak considerably. Furthermore, Radak's dedication to Maimonidean rationalism, which has been amply demonstrated by scholars, would only have sharpened his resistance to fanciful midrashic speculation.
Purity Studies in Judaism: An Emerging Subfield?
Authors: Fonrobert Charlotte Elisheva
Published: April 2007

Studies of textual traditions about menstruation in Judaism are seldom without an agenda. Perhaps they cannot be. The polemical history of the literature is simply too entrenched by now. This is also the case with Evyatar Marienberg's series of studies, recently published in France, about the place of menstruation in Jewish culture.
Law, Gender and Religious Belief in Europe: Considerations from a Catholic Perspective
Authors: Opromolla Adriana
Published: April 2007

In the teaching of the Catholic Church, the institution of marriage derives directly from God, for common good and for the good of spouses and children. Human authorities are called upon not to transform its characteristics and to avoid any attempts to distort them. However, the Church is today confronted with a changing understanding of the notion of ‘gender’ and with new considerations about the meaning of ‘marriage’ on behalf of parts of society and of political institutions. Based on an overview of the recent legislative and political proposals concerning family issues at the European level, this article aims to assess what model of family the Member States of the European Union are developing, and how the traditional concept of marriage could be influenced by this evolution.
Islam and the European Union
Authors: Goddard Hugh
Published: April 2007

RICHARD POTZ AND WOLFGANG WIESHAIDER Peeters, Leuven, 2004, xi+263 pp (€45.00) ISBN: 978-90-429-1445-2
MATERNAL TEMPERATURE IN LABOUR
Authors: BAILEY CLAIRE , STEER PHILIP J
Published: April 2007

In this review, we are concerned primarily with pyrexia (hyperthermia; increased maternal temperature in labour) as hypothermia is rare and usually iatrogenic (as in hypothermia for cardiac bypass surgery). We start by reviewing the factors determining maternal temperature, and how it can be measured. We move on to the effects of the commonest cause of maternal pyrexia in labour in modern obstetric practice in developed countries, epidural anaesthesia. We then discuss the most feared cause of maternal pyrexia in labour, chorioamnionitis.
Formation of thrombus in a native aortic sinus of Valsalva after palliation of hypoplastic left heart syndrome
Authors: Mookerjee Joydeep , Rosenthal Eric , Simpson John M.
Published: April 2007

An eight-month-old girl with hypoplastic left heart syndrome, who underwent a modified Norwood operation at the age of two days, and a Hemifontan operation at five months of age, had severely impaired ventricular function and new electrocardiographic changes. Coronary angiography demonstrated a small adherent thrombus in the non-coronary sinus of Valsalva of the native aortic root, which may be the cause of unexplained ventricular dysfunction.