bluuebunny/crossref_metadata_2025 huggingface dataset:
Obstetric outcome after fetal reduction to singleton pregnancies
Authors: De Catte L. , Foulon W.
Published: August 2002

Objective

To study the outcome after fetal reduction or selective termination to singleton pregnancies for various indications.

Methods

Fetal reduction or selective feticide to singleton pregnancies was performed in 80 multiple gestations (congenital malformations, 17 cases; high‐risk obstetric conditions, 25 cases; or social/psychological indications, 38 cases).

Results

The overall pregnancy loss rate was 10%; however, pregnancy failure was significantly higher in selective reductions performed for preterm prelabor rupture of membranes (PPROM) (4/8) compared with monochorionic twin and bad obstetric history. Fetal reduction to singletons for psychological reasons resulted in a pregnancy wastage of 5.3% (2/38). Procedures performed at ≤14 weeks showed a significantly lower fetal loss rate (2/61; 3.3%), a higher mean gestational age at delivery (38.3±2.2 weeks), and a decreased prematurity rate (p≤0.001). The number of reduced fetuses, prenatal diagnosis by chorionic villus sampling before the reduction and maternal age did not interfere with pregnancy outcome.

Conclusion

Fetal reduction to singleton pregnancies has a favorable outcome, especially when performed before 14 weeks of gestation. Copyright © 2002 John Wiley & Sons, Ltd.
Kinetics of the reaction of β‐alkoxyvinyl methyl ketones with amines
Authors: Vdovenko Sergei I. , Gerus Igor I. , Wójcik Jacek
Published: August 2002

The kinetics of the reaction of β‐alkoxyvinyl methyl ketones R1O—CR2CH— COCX3 (1a–e)(a, R1CH3, R2H, XH; b, R1C2H5, R2H, XF; c, R1C2H5, R2H, XCl; d, R1R2CH3, XCl;e, R1R2CH3, XF) with aliphatic amines was studied in various solvents. The details of appropriate enaminoketone (2a–d) formation are discussed in terms of an addition–elimination reaction. It is shown that the limiting step of the reaction is the decomposition of a zwitterionic intermediate, and that the observed second‐order reaction rate constants are a function of the solvent's relative permittivity ϵr. At high amine concentrations in non‐polar solvents, the third‐order rate coefficient appears in the reaction rate equation as a consequence of a catalyzed route of the intermediate decomposition. The reaction has low ΔH≠ and high negative ΔS≠ values owing to the formation of a highly polar zwitterionic intermediate. Its lifetimes are determined mainly by the electron‐withdrawing ability of COCX3. Copyright © 2001 John Wiley & Sons, Ltd.
Reduction of the 2‐azetidinone moiety in the polymer main chain: A novel synthetic route to polyamine with hydroxymethyl pendant
Authors: Sudo Atsushi , Sato Masato , Endo Takeshi
Published: August 2002

A polymer with a 2‐azetidinone moiety in its main chain was efficiently synthesized by [2 + 2] cycloaddition of bisimine with bisketene. The bisketene was easily prepared by dehydrochlorination of the corresponding dicarboxylic acid chloride and was used without purification. The treatment of the obtained polymer with lithium aluminum hydride resulted in a reductive ring‐opening reaction of the 2‐azetidinone moiety in the main chain that gave the corresponding linear polyamine with hydroxymethyl side chains. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3789–3796, 2001
Copolycondensations of bisphenols with aggregates of isophthalic acid and terephthalic acid activated by tosyl chloride/dimethylformamide/pyridine in different manners
Authors: Higashi Fukuji , Shirai Takayo , Mitani Kiyoshi , Sugishita Kanako
Published: August 2002

A mixture of isophthalic acid (IPA) and terephthalic acid (TPA) was activated by a tosyl chloride/dimethylformamide/pyridine (Py) condensing agent in two steps via the treatment of a mixture of the initially activated IPA/TPA with additional TPA followed by the activation of TPA with the agent. The resulting mixture showed a solubility in Py different from that obtained by the activation of them all at once; the difference might be due to different structures of the aggregates of the activated IPA and TPA at the same composition of the diacids. The structures of the aggregates were evaluated on the basis of melting points and the IR spectra of a mixture of dimethyl esters of IPA and TPA produced by the quenching of the reaction mixtures with methanol. The mixture obtained by two‐step activation showed lower melting points and spectral changes due to enhanced associations of the esters with respect to the mixture prepared by the activation of them all at once. The aggregates were also examined in terms of the distributions of IPA and TPA in thermotropic copolyesters prepared from methylhydroquinone and chlorohydroquinone by their transition temperatures and 13C NMR. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3884–3892, 2001
2,2,6,6‐Tetramethyl‐1‐piperidinyl‐oxyl/[bis(acetoxy)‐iodo]benzene‐mediated oxidation: A versatile and convenient route to poly(ethylene glycol) aldehyde or carboxylic acid derivatives
Authors: Masson Christophe , Scherman Daniel , Bessodes Michel
Published: August 2002

A new and very convenient route to oxidized poly(ethylene glycol), with a catalytic nitroxyl radical oxidant (2,2,6,6‐tetramethyl‐1‐piperidinyl‐oxyl) regenerated in situ by stoichiometric amounts of [bis(acetoxy)‐iodo]benzene, is described. Under these conditions, the reaction is quantitative and leads to the pure product by a simple process such as precipitation and washing with diethyl ether. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4022–4024, 2001
Glycoconjugated polymer. I. Synthesis and characterization of amphiphilic polystyrenes with glucose, maltose, and maltohexaose as hydrophilic segments
Authors: Narumi Atsushi , Kaga Harumi , Kawasaki Kosei , Taniguchi Yasuo , Satoh Toshifumi , Kakuchi Toyoji
Published: August 2002

Glucosyl styrene (1a), maltosyl styrene (1b), and maltohexaosyl styrene (1c) were prepared by the glycosylation of 4‐vinylbenzyl alcohol with the corresponding glycosyl trichloroacetimidates with boron trifluoride diethyl ether complex. The copolymerizations of 1a–1c with styrene were carried out with 2,2′‐azobis(2‐methylpropionitrile) as an initiator in dry N,N‐dimethylformamide at 60 °C, and this was followed by deacetylation to produce amphiphilic polystyrenes with glucose (3a), maltose (3b), and maltohexaose (3c) as hydrophilic segments. 3 showed various solubility characteristics that were dependent on the content of glucose residues, especially within a range of 20–50 wt %. The solubility characteristics of 3, related to the copolymer composition, indicated that the hydrophilic property was remarkably improved with an increased number of glucose units, that is, in the order 3a < 3b ≪ 3c. The results described in this article provide useful information for the design of glycoconjugated architectures with desired amphiphilic properties. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4061–4067, 2001
Polythiophene formation within hyperbranched grafts on polyethylene films
Authors: Bergbreiter David E. , Liu Martha L.
Published: August 2002

Interphase oligomerization of thiophene within a supported thin film is described. Polyethylene (PE) surfaces containing an irregularly hyperbranched poly(acrylic acid) (PAA) graft were first prepared by multistep grafting of poly(tert‐butylacrylate) onto oxidized PE. The product ultrathin PAA grafts were then further modified by amidation or esterification with thiophenes containing amino or hydroxyl groups to form new interfaces containing thiophene monomers. These thiophene‐modified grafts were characterized by attenuated total reflectance infrared spectroscopy and were shown to be suitable as substrates in an oxidative polymerization method with FeCl3 as an oxidant. The product 2,5‐coupled thiophene oligomers (3‐PAA/PE–oligomerized thiophene ester, OTE) emitted a yellow‐green light under UV irradiation, indicating that a conjugated fluorescence oligothiophene had been prepared within these hyperbranched films. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4119–4128, 2001
Metallocene derivatives as active supports of zirconium‐based catalysts for ethene polymerization
Authors: Mortara Stefano , Fregonese Daniele , Bresadola Silvano , Boaretto Rita , Sostero Silvana
Published: August 2002

Cyclopentadienyl magnesium chloride (MgClCp) and its functionalized derivatives represent original and interesting supporting materials to heterogenize metallocene catalysts for olefin polymerizations. The synthesis of MgClCp, its functionalization, and the preparation of a catalytic system in which the ZrCl2(Flu)+ moiety is joined on the support through a cyclopentadienyl ligand are reported. This catalyst was tested in ethene polymerization, and both the catalytic activity and properties of the produced polymer were measured. Its performance was compared with that shown by the catalyst ZrCl2CpFlu employed under the same conditions for both unsupported and conventional supports, such as MgCl2. The results showed a remarkable improvement in terms of the activity and polymer properties with these heterogenized catalysts. Moreover, this system showed stability toward leaching processes and was characterized by good morphological control of the growing polymer. Finally, catalysts in which [HB(3,5‐Me2pyrazolyl)3]ZrCl and [HB(3,5‐Me2pyrazolyl)3]ZrClOtBu+ moieties were bonded to a functionalized MgClCp− support were also synthesized and tested. The results showed that the proposed supports could be usefully used to heterogenize tailored metallocene homogeneous catalysts. In fact, new catalysts were prepared that combined the peculiar advantages of both heterogeneous and homogeneous catalysts and overcame the disadvantages of the latter, such as a lack of morphology and reactor fouling. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4243–4248, 2001
High‐temperature elastomers from silarylene‐siloxane‐diacetylene linear polymers
Authors: Homrighausen Craig L. , Keller Teddy M.
Published: August 2002

The syntheses and characterization of linear silarylene‐siloxane‐diacetylene polymers 3a–c and their thermal conversion to crosslinked elastomeric materials 4a–c are discussed. Inclusion of the diacetylene unit required synthesis of an appropriate monomeric species. 1,4‐Bis(dimethylaminodimethylsilyl)butadiyne [(CH3)2N Si(CH3)2CCCC(CH3)2SiN(CH3)2] 2 was prepared from 1,4‐dilithio‐1,3‐butadiyne and 2 equiv of dimethylaminodimethylchlorosilane. The linear polymers were prepared via polycondensation of 2 with a series of disilanol prepolymers. The low molecular weight silarylene‐siloxane prepolymers 1a–c (terminated by hydroxyl groups) were synthesized via solution condensation of an excess amount of 1,4‐bis(hydroxydimethylsilyl)benzene with bis(dimethylamino)dimethylsilane. The linear polymers were characterized by 1H and 13C NMR, Fourier transform infrared spectroscopy, gel permeation chromatography, thermogravimetric analysis (TGA), and DSC. The elastomers exhibited long‐term oxidative stability up to 330 °C in air as determined by TGA. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 88–94, 2002
Synthesis of end‐functionalized poly(methyl methacrylate) by ruthenium‐catalyzed living radical polymerization with functionalized initiators
Authors: Baek Kyung‐Youl , Kamigaito Masami , Sawamoto Mitsuo
Published: August 2002

A series of functionalized 2‐bromoisobutyrates and 2‐chloro‐2‐phenylacetates led to α‐end‐functionalized poly(methyl methacrylate)s in Ru(II)‐catalyzed living radical polymerization; the terminal functions included amine, hydroxyl, and amide. These initiators were effective in the presence of additives such as Al(Oi‐Pr)3 and n‐Bu3N. The chlorophenylacetate initiators especially coupled with the amine additive gave polymers with well‐controlled molecular weights (Mw/Mn = 1.2–1.3) and high end functionality (Fn ∼ 1.0). © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1937–1944, 2002
Synthesis and electrooptic properties of side‐chain methacrylate polymers containing a new azophenylbenzoxazole chromophore
Authors: Beltrani T. , Bösch M. , Centore R. , Concilio S. , Günter P. , Sirigu A.
Published: August 2002

The synthesis and characterization of four methacrylate copolymers obtained by radical addition polymerization of methyl methacrylate as well as a new methacrylate azophenylbenzoxazole chromophore in percentages of 10, 30, 50, and 70% were explored. The copolymers were amorphous and showed glass‐transition temperatures ranging from 132 to 146 °C. High‐quality polymer films were easily obtained by spin coating from N‐methylpyrrolidone solutions. Polymer films spun cast on iridium tin oxide (ITO) substrates were used in the electro‐optic (EO) experiments to evaluate the EO coefficients r33 using the reflection technique. The measured values fell in the range of 1.7–3.7 pm/V (laser incident wavelength of 1.552 μm) depending on the percentage of chromophore in the polymer. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1162–1168, 2001
Cationic ring‐opening polymerization of six‐membered cyclic carbonates with ester groups
Authors: Nemoto Nobukatsu , Sanda Fumio , Endo Takeshi
Published: August 2002

This work deals with the cationic ring‐opening polymerization of the ester‐substituted cyclic carbonates 5‐methyl‐5‐benzoyloxymethyl‐1,3‐dioxan‐2‐one (CC1) and 4‐benzoyloxymethyl‐1,3‐dioxan‐2‐one (CC4). The polymerization was carried out with trifluoromethanesulfonic acid, methyl trifluoromethanesulfonate, boron trifluoride etherate, or methyl iodide as the initiator. The reactivity of CC1 and CC4 was higher than that of 5,5‐dimethyl‐1,3‐dioxan‐2‐one, which had no ester moiety. These results suggest that this ring‐opening polymerization was accelerated by the intramolecular ester group. CC1 showed a higher polymerizability than CC4, affording a polymer with a higher molecular weight. Additionally, using methyl iodide as the initiator was effective for increasing the molecular weight of the obtained polycarbonate and decreasing decarboxylation. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1305–1317, 2001
Synthesis and characterization of liquid–crystalline polyesters with chiral and achiral twin spacers
Authors: Srinivasan Rukmani , Radhakrishnan Ganga
Published: August 2002

A series of novel thermotropic main‐chain chiral liquid–crystalline random copolyesters consisting of spacers of two different types—chiral and achiral—was synthesized. Polyesters (BmTa) with tartaric acid as the chiral spacer (Ta), aliphatic diols (with ‘m’ = 2–10 methylene groups) as the achiral spacers, and 4,4′‐dihydroxy biphenyl (B) as the mesogen were synthesized via condensation polymerization in solution after duly protecting the 2,3‐dihydroxy groups of tartaric acid by acetylation. The copolymers were characterized by Fourier transform infrared spectroscopy, 1H and 13C NMR spectra, gel permeation chromatography, and thermogravimetric analysis. Transition temperatures for phase changes recorded by DSC were corroborated with the textures observed by a hot‐stage optical polarizing microscope. The wide‐angle X‐ray diffraction (WAXD) profiles indicated a SmE phase at room temperature. The lower angle region at 2θ = 0.5–2.45 covered by WAXD indicated a layer of thickness of 161 Å, less than the molecular length for B0Ta. The [αD] values were recorded on a digital polarimeter. The birefringence was lost at higher mesophase temperatures in lower members with m < 5, a behavior found in certain chiral systems, and the higher members with m > 5 showed a lesser number of phase transitions. On cooling, the polyesters produced a texture with the formation of transition bars. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1743–1752, 2001
Hyperbranched aromatic poly(ether imide)s: Synthesis, characterization, and modification
Authors: Wu Fang‐Iy , Shu Ching‐Fong
Published: August 2002

The synthesis and characterization of hyperbranched aromatic poly(ether imide)s are described. An AB2 monomer, which contained a pair of phenolic groups and an aryl fluoro moiety activated toward displacement by the attached imide heterocyclic ring, was prepared. The nucleophilic substitution of the fluoride with the phenolate groups led to the formation of an ether linkage and, subsequently, to the hyperbranched poly(ether imide), which contained terminal phenolic groups. A similar one‐step polymerization involving a monomer that contained silyl‐protected phenols yielded a hyperbranched poly(ether imide) with terminal silylated phenols. The degree of branching of these hyperbranched polymers was approximately 55%, as determined by a combination of model compound studies and 1H NMR integration experiments. End‐capping reactions of the terminal phenolic groups were readily accomplished with a variety of acid chlorides and acid anhydrides. The nature of the chain‐end groups significantly influenced physical properties, such as the glass‐transition temperature and the solubility of the hyperbranched poly(ether imide)s. As the length of the acyl chain of the terminal ester groups increased, the glass‐transition temperature value for the polymer decreased, and the solubility of the polymer in polar solvents was reduced, becoming more soluble in nonpolar solvents. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2536–2546, 2001
Synthesis of carboxy‐telechelic oligostyrene by dead‐end polymerization: Evaluation of primary radical termination by kinetic study and kinetic simulation model
Authors: David Ghislain , Robin Jean‐Jacques , Boutevin Bernard
Published: August 2002

Styrene was polymerized with azobiscyanovaleric acid (ACVA) to obtain carboxy‐telechelic polystyrene. Our aim was to synthesize an oligostyrene with a molecular weight of about 2000 g/mol. Thus, styrene was polymerized at 90 °C, where t1/2ACVA is very short, and at very high initiator concentrations. In these conditions a new termination reaction appeared, known as the primary radical termination (PRT). At first, PRT was observed by a deviation from the simple kinetic law. Then, the constant of PRT was determined by several kinetic models to be more important than the constant of bimolecular termination. Finally, the PREDICI simulation program was used to confirm the predominance of PRT. This simulation program allowed the determination of the constant of primary radical deactivation krr and the influence of this reaction on the conversion rate. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2740–2750, 2001
Mechanism of emulsion polymerization of styrene using a reactive surfactant
Authors: Wang X. , Sudol E. D. , El‐Aasser M. S.
Published: August 2002

The emulsion polymerization of styrene using the reactive surfactant sodium dodecyl allyl sulfosuccinate (TREM LF‐40) was studied. The polymerization kinetics were found to be unusual in that Rp was not directly proportional to Np (Rp ∝ Np0.67). Several reasons are stated to explain the unusual kinetics, including chain transfer to TREM LF‐40, copolymerization of styrene with TREM LF‐40, and the influence of the homopolymer of TREM LF‐40 [poly(TREM)] and/or the copolymer [poly(TREM‐co‐styrene)] on the entry and exit rates of free radicals. The possibility of both chain transfer and copolymerization exists primarily at the oil/water interface, whereas both can also occur in the aqueous and monomer phases. Bulk polymerizations of styrene in the presence of TREM LF‐40 and poly(TREM) were conducted, and the results show that the reaction rate decreased for the styrene/TREM LF‐40 system. Latex characterization by serum replacement and titration measurements provided evidence for the chemical bonding of TREM LF‐40 to the polymer particles. The fraction of chemically bound reactive surfactant decreased with increasing surfactant concentration and increased with increasing initiator concentration. Relatively high contact angles of water on films cast from the latexes showed that TREM LF‐40 did not migrate significantly to the surface of the film, which was consistent with the latex‐surface characterization results. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3093–3105, 2001
Adhesive and mechanical properties of soft nanocomposites: Model studies with blended latex films
Authors: Fabbroni Elizabeth F. , Shull Kenneth R. , Hersam Mark C.
Published: August 2002

We used a unique approach based on contact mechanics to quantify the adhesive and linear viscoelastic properties of latex films approximately 100 μm thick. The latex films were formed from a mixture of two particle types and form stable films consisting of rigid and compliant regions. We used atomic force microscopy to verify that these regions remained well dispersed on the length scale of the original particle size. The properties of the films were determined by ϕh, the volume fraction of the stiffer component. For ϕh < 0.45, the films were quite adhesive, with viscoelastic properties determined by the compliant matrix material. Adhesive interactions between the film and indenter enabled us to oscillate the indenter in the direction normal to the film surface while maintaining a constant contact area, allowing us to determine the frequency dependence of the dynamic moduli of the films. Stiffer films with higher volume fractions of hard particles were characterized by indentation measurements, from which we were able to determine the time dependence of the relaxation modulus of the latex films. All results were consistent with a power‐law form of the relaxation modulus with an exponent of 0.25. The magnitude of the relaxation modulus increased by a factor of 3000 as the volume fraction of hard particles increased from 0 to 0.89. For low values of ϕh, the composition dependence of the film stiffness was similar to the concentration dependence of the viscosity of spherical particle suspensions. A much weaker concentration dependence was observed for the highest values of ϕh, where the properties of the films were dominated by the stiffer component. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 3090–3102, 2001
Dynamic evolution of gases in the γ‐ and helium‐ion radiolyses of solid polymers
Authors: Chang Z. , Laverne Jay A.
Published: August 2002

The dynamic evolution of gaseous hydrogen, methane, and carbon dioxide in the γ‐ and 4He‐ion radiolyses of solid polymers was investigated. The polymers used include low‐density and high‐density polyethylene, polypropylene, polystyrene, poly(methyl methacrylate), Nylon 11, Nylon 6, and poly(dimer acid‐co‐alkyl polyamine). An inline quadrupole mass spectrometer was utilized to monitor the dynamic profiles of the gases produced in the radiolysis. One‐ and two‐dimensional numerical diffusion models were developed to simulate and extract optimum diffusion coefficients and gas yields from the experimental dynamic gas profiles. It was found that the dynamic evolution of molecular hydrogen from the bulk polymer is controlled by its diffusion in most cases, such as CO2 in poly(methyl methacrylate). In the γ radiolysis of some polymers such as low‐density polyethylene and polypropylene, the dynamic evolution of methane is only partially controlled by the diffusion process, and some other postirradiation process is a factor. It is concluded that the simulation method developed in this article is helpful in understanding and predicting the mechanisms of gas evolution in the radiolysis of solid polymers. © 2001 John Wiley & Sons, Inc. J Polym Sci B Part B: Polym Phys 39: 1449–1459, 2001
Characterization of chemical heterogeneity in polymer systems using hydrolysis and tapping‐mode atomic force microscopy
Authors: Raghavan D. , Gu X. , Nguyen T. , Vanlandingham M.
Published: August 2002

Characterization of polymer coatings microstructure is critical to the fundamental understanding of the corrosion of coated metals. An approach for mapping the chemical heterogeneity of a polymer system using chemical modification and tapping‐mode atomic force microscopy (TMAFM) is demonstrated. This approach is based on the selective degradation of one of the phases in a multiphase polymer blend system and the ability of TMAFM to provide nanoscale lateral information about the different phases in the polymer system. Films made of a 70:30 polyethyl acrylate/polystyrene (PEA/PS) blend were exposed to a hydrolytic acidic environment and analyzed using TMAFM. Pits were observed to form in the PEA/PS blend films, and this degradation behavior was similar to that of the PEA material. Using these results, the domains in the 70:30 blend were identified as the PS‐rich regions and the matrix as the PEA‐rich region. This conclusion was confirmed by Fourier transform infrared‐attenuated total reflection analyses that revealed the hydrolysis of the PEA material. TMAFM phase imaging was also used to follow pit growth of the blend as a function of exposure time. The usefulness of the chemical modification/AFM imaging approach in understanding the degradation process of a coating film is discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci B Part B: Polym Phys 39: 1460–1470, 2001
Selective fiberoptic left main‐stem intubation for severe unilateral barotrauma in a 24‐week premature infant
Authors: Meyer Michael T. , Rice Tom B. , Glaspey John C.
Published: August 2002

A 24‐week premature infant developed severe right‐sided pulmonary barotrauma secondary to mechanical ventilation for respiratory distress syndrome (RDS). High‐frequency oscillatory ventilation and permissive hypercapnia were initiated. A chest tube was placed to relieve a pneumothorax, and a catheter was inserted into an air‐filled cyst for drainage. These maneuvers failed to improve the child's respiratory status.

The child's left main‐stem bronchus was then successfully fiberoptically intubated for single‐lung ventilation in order to reduce the unilateral barotrauma. Single‐lung ventilation was effectively and safely continued for 5 days, with complete resolution of the pulmonary barotrauma. Pediatr Pulmonol. 2002; 33:227–231. © 2002 Wiley‐Liss, Inc.
Determinants of bronchial responsiveness to methacholine at school age in twin pairs
Authors: Nikolajev Kari , Korppi Matti , Remes Kyllikki , Länsimies Esko , Jokela Veikko , Heinonen Kirsti
Published: August 2002

The methacholine inhalation challenge test (MIC) was used to evaluate bronchial responsiveness in 67 children who were the products of multiple pregnancies when they were 7–15 years old.

At birth, 30 (45%) infants had intrauterine growth retardation (IUGR; birth weight < 2 SD below normal birth weight, or birth weight difference > 1.3 SD between twin‐pairs), and 59 (88%) were born before 37 weeks of gestation. None of the children had doctor‐diagnosed asthma. The provocative dose of methacholine causing a 20% fall in Wright's peak expiratory flow (WPEF) (PD20) was below 1,000 μg in 10 (15%) children, and they were classified as MIC responders. There were no differences in perinatal or neonatal factors between MIC responders and nonresponders; in particular, MIC responses did not differ between IUGR infants, and children with appropriate growth for gestational age (AGA) at birth. There were seven discordant pairs in which one child was a MIC responder and the other was not; 5 responders were IUGR, and 2 were AGA children (ns). Respiratory tract infections after the neonatal period were equally common in IUGR and AGA children. However, these infections were associated with later bronchial hyperresponsiveness. Doctor‐diagnosed respiratory infections, numbers of antibiotic courses, episodes of otitis media, and the need for adenoidectomy, tonsillectomy, and tympanostomy were more common in MIC responders than in nonresponders.

We conclude that IUGR was not associated with subsequent bronchial hyperresponsiveness in twin pairs assessed by the MIC test. A significant relationship was seen between bronchial hyperresponsiveness and infections after the neonatal period. Pediatr Pulmonol. 2002; 33:167–173. © 2002 Wiley‐Liss, Inc.
Impact of a multidisciplinary day program on disease and healthcare costs in children and adolescents with severe asthma: A two‐year follow‐up study
Authors: Bratton Donna L. , Price Marcella , Gavin Leslie , Glenn Karen , Brenner Manon , Gelfand Erwin W. , Klinnert Mary D.
Published: August 2002

For patients whose asthma remains in poor control necessitating high utilization of medical services, a referral to a specialized “center of excellence” is often considered. A decade ago, we evaluated our pediatric asthma program of long‐term hospitalization (median stay of 75 days) and found significant decreases in subjects' medical utilization following this intervention. In an effort to contain treatment costs, the former program was markedly altered to one of abbreviated stay with emphasis on family management of asthma. The purpose of the present study was to determine the outcome of children treated in the revised program with regard to disease severity, quality of life, and subsequent utilization of medical resources. Children with severe asthma who were admitted to the program and fulfilled study criteria were consecutively enrolled. Data was obtained concerning disease characteristics, treatment, and quality of life at admission, and at 1 and 2 years following discharge. Medical records for the year prior to program admission and for the 2 years following discharge were coded for medical care encounters.

Ninety‐eight children, aged 9 months to 18 years (mean age, 10.9 years), were enrolled. They participated in the program for a mean of 15.6 ( ± 8 SD), median of 15.0, and range of 2–51 treatment days. The group showed significant improvement (P < 0.0001) from admission to 1‐ and 2‐year follow‐up in median corticosteroid use, asthma functional severity, perceived competence in asthma management, and quality of life for both caregiver and child. Medical record data showed significant improvement (P < 0.0001) at both 1‐ and 2‐year follow‐up in median number of corticosteroid bursts, emergency department visits, hospital days, and overall utilization of medical care encounters. A median total medical encounter cost/patient of $16,250 ($6,972–$25,714 interquartile range (IQR)) for the year prior to program participation was reduced to $1,902 ($505–$6,524 IQR) at 1‐year and $690 ($185–$3,550 IQR) at 2‐ year follow‐up (P < 0.0001).

We conclude that multidisciplinary care in a short‐term, outpatient, day treatment program can significantly contribute to improvement in asthma severity, quality of life, and reduction in healthcare costs. Pediatr Pulmonol. 2001; 31:177–189. © 2001 Wiley‐Liss, Inc.
Effect of acidic phospholipids on the structural properties of recombinant cytosolic human glyoxalase II
Authors: Scirè Andrea , Saccucci Franca , Bertoli Enrico , Cambria Maria Teresa , Principato Giovanni , D'Auria Sabato , Tanfani Fabio
Published: August 2002

A peculiar characteristic of highly concentrated cytosolic recombinant human glyoxalase II (GII) solutions is to undergo partial precipitation. Previous work indicated that anionic phospholipids (PLs) exert a noncompetitive inhibition on the enzymatic activity of the soluble enzyme. In this study, FTIR spectroscopy was used to analyze the structural properties and the thermal stability of the soluble protein in the absence and in the presence of liposomes made of different phospholipids (PLs). The structural analysis was performed on the precipitate as well. The interaction of acidic PLs with GII lowered the thermal stability of the enzyme and inhibited protein intermolecular interactions (aggregation) brought about by thermal denaturation. Infrared data indicated that ionic and hydrophobic interactions occur between GII and acidic PLs causing small changes in the secondary structure of the enzyme. No interactions of the protein with egg phosphatidylcholine liposomes were detected. The results are consistent with the destabilization of the protein tertiary structure, and indicate that GII possesses hydrophobic part(s) that interact with the acyl chains of PLs. Data on precipitated GII did not show remarkable modification of secondary structure, suggesting that hydrophobic stretches of the enzyme may also be involved in the protein–protein association (precipitation) at high GII concentration. The alterations in the GII structure and the noncompetitive inhibition exerted by acidic PLs are strictly related. Proteins 2002;48:126–133. © 2002 Wiley‐Liss, Inc.
Predicted impact of transgenic, herbicide‐tolerant corn on drinking water quality in vulnerable watersheds of the mid‐western USA
Authors: Wauchope R Don , Estes Tammara L , Allen Richard , Baker James L , Hornsby Arthur G , Jones Russell L , Richards R Peter , Gustafson David I
Published: August 2002

In the intensely farmed corn‐growing regions of the mid‐western USA, surface waters have often been contaminated by herbicides, principally as a result of rainfall runoff occurring shortly after application of these to corn and other crops. In some vulnerable watersheds, water quality criteria for chronic human exposure through drinking water are occasionally exceeded. We selected three settings representative of vulnerable corn‐region watersheds, and used the PRZM‐EXAMS model with the Index Reservoir scenario to predict corn herbicide concentrations in the reservoirs as a function of herbicide properties and use pattern, site characteristics and weather in the watersheds. We compared herbicide application scenarios, including broadcast surface pre‐plant atrazine and alachlor applications with a glyphosate pre‐plant application, scenarios in which losses of herbicides were mitigated by incorporation or banding, and scenarios in which only glyphosate or glufosinate post‐emergent herbicides were used with corn genetically modified to be resistant to them. In the absence of drift, in almost all years a single runoff event dominates the input into the reservoir. As a result, annual average pesticide concentrations are highly correlated with annual maximum daily values. The modeled concentrations were generally higher than those derived from monitoring data, even for no‐drift model scenarios. Because of their lower post‐emergent application rates and greater soil sorptivity, glyphosate and glufosinate loads in runoff were generally one‐fifth to one‐tenth those of atrazine and alachlor. These model results indicate that the replacement of pre‐emergent corn herbicides with the post‐emergent herbicides allowed by genetic modification of crops would dramatically reduce herbicide concentrations in vulnerable watersheds. Given the significantly lower chronic mammalian toxicity of these compounds, and their vulnerability to breakdown in the drinking water treatment process, risks to human populations through drinking water would also be reduced.

© 2001 Society of Chemical Industry
Passive control methods for seismic response modification
Authors: Towashiraporn P , Park J , Goodno B J , Craig J I
Published: August 2002

Passive energy dissipation devices have been successfully implemented in buildings around the world to reduce structural response, primarily due to earthquakes, but also for wind and other dynamic loading conditions. The basic objective in using passive energy dissipation devices is to try to concentrate as much of the energy dissipation as possible into specially designed devices, rather than to allow it to develop in the primary structural elements, and thereby to reduce damage in the main structure. Passive approaches differ from active ones in that they do not require any external sources of power to operate, and this is particularly useful in situations such as earthquakes where power is likely to be interrupted when it is most needed.

The focus of this paper is a review of passive energy dissipation devices for seismic response modification applications. Past developments and contemporary examples of metallic hysteresis, friction and viscoelastic devices suitable for building applications are included in the first part of the paper. Current design guidelines based on both linear and nonlinear procedures are summarized next. Finally, three recent applications of metallic hysteretic damping devices are described. The first two examples present the use of metallic damping devices as cladding connections, while the third example shows an application of metallic devices in a relatively stiff, unreinforced masonry building. These examples show the potential versatility of passive energy dissipation devices and illustrate some of the analysis methods that might be used.
Tea pigments inhibit the production of type 1 (TH1) and type 2 (TH2) helper T cell cytokines in CD4+ T cells
Authors: Tomita Michiyo , Irwin Kara I. , Xie Zi‐Jian , Santoro Thomas J.
Published: August 2002

Tea pigments are oxidized products of polyphenols derived from tea leaves (Camellia sinensis). Theaflavins are constituents of tea pigments with antioxidant, antineoplastic and antiinflammatory properties similar to their parent compounds. The biological properties of polyphenols and theaflavins have been linked to their capacity to inhibit the activation of nuclear factor‐κB (NF‐κB), a transcription factor, which is critically involved in the molecular regulation of a number of proinflammatory cytokines. The current study examines the requirement for NF‐κB in the immunosuppressive effects mediated by tea antioxidants. Specifically, we tested the hypothesis that cytokines produced by type 1 (TH1) CD4+ T cells which require NF‐κB for gene expression, such as interleukin‐2 (IL‐2) and interferon gamma (IFN γ), are selectively inhibited by tea pigments. We found that tea pigments potently suppress IL‐2 secretion, IL‐2 gene expression and the activation of NF‐κB in murine spleens enriched for CD4+ T cells, as expected. Consistent with our hypothesis, tea pigments also inhibited the induction of IFNγ mRNA. However, the expression of the TH2 cytokines IL‐4 and IL‐5, which lack functional NF‐κB sites within their promoters was unexpectedly suppressed by tea pigments, as well. The results indicate that NF‐κB may be only one of multiple transcription factors inhibited by tea pigments. Copyright © 2002 John Wiley and Sons, Ltd.
Determination of stability of MIG/MAG welding processes
Authors: Suban Marjan
Published: August 2002

The paper treats several methods of evaluating the stability of MIG/MAG welding processes, which are based on measurement of time‐varying welding‐current intensity and welding voltage. The stability of the welding process is affected by numerous parameters. The most unfavourable result of poor stability are spatters, which are problematic in terms of material losses and extension of production times due to cleaning, as well as appearance. The experimental part of the paper is based on stability analyses carried out with three different gas‐shielding atmospheres. Two different welding domains were compared. The first was short‐circuit material transfer, and the second spraying material transfer. The results obtained in the analysis of the signals measured indicate a more stable short‐circuit material transfer in the case of welding with the pure CO$_2$ gas, and a more stable spray material transfer in the case of welding with the transferred ionized molten energy mixture. Copyright © 2001 John Wiley & Sons, Ltd.
Analysis of difference two‐electron density matrix between two states of magnetic molecules
Authors: Yamaki D. , Nagao H. , Yamaguchi K.
Published: August 2002

Previously, a method based on the two‐electron density matrix (2‐DM) has been used to obtain chemical interpretations with electron correlations. In the method, a 2‐DM is expanded by its natural geminals. These natural geminals are visualized to obtain their chemical interpretations. An electronic state is understood as the set of geminals that have various correlations of two electrons. In this work, a extension of previous 2‐DM‐based method is described to compare two states of a system. In this method, the difference 2‐DM between the two states is used instead of 2‐DM itself. The applications of the method to trans‐butadiene and trimethylene methane are shown. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Variation of the ℏω with the particle number and the appearance of “kinks” for atomic clusters
Authors: Kotsos B. A. , Grypeos M. E.
Published: August 2002

The dependence of the harmonic oscillator (HO) energy level spacing ℏω on the particle number N is studied analytically for atomic (metal) clusters on the basis of their electronic densities, parametrizing Ekardt's results (for sodium clusters) by means of a Fermi distribution. An interesting feature of such an approach is that it leads, under the assumptions made, to “kinks,” that is, to “marked discontinuities in the slope” of ℏω at the closed shells. These discontinuities diminish as N increases. For large N, ℏω becomes simply: ℏω≃c1N−1/3+c2N−1. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Approximate solution of the representability problem
Authors: Panin A. I.
Published: August 2002

Approximate solution of the ensemble representability problem for density operators of arbitrary order is obtained. This solution is closely related to the “Q condition” of A. J. Coleman. The representability conditions are formulated in orbital representation and are easy to use. A general scheme of construction of the contraction operator right inverses is proposed and the explicit expression for the right inverse associated with the expansion operator is derived as an example. Two algorithms of direct two‐density matrix determination are proposed. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 85: 1–17, 2001
Identification of hemes and related cyclic tetrapyrroles by matrix‐assisted laser desorption/ionization and liquid secondary ion mass spectrometry
Authors: Youn Hyung‐Sun , Burkhalter Robert S. , Timkovich Russell
Published: August 2002

Mass spectrometry has proven to be a powerful technique applicable on trace amounts for the identification of known hemes and cyclic tetrapyrroles, and for providing critical information for the structure of new and novel versions. This report describes investigations of the practical limits of detection for such bioinorganic prosthetic groups, primarily by liquid secondary ion mass spectrometry (LSIMS) and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS), including a survey of the utility of common matrices. The lower limit of detection under favorable conditions extends to low picomole amounts. Certain derivatization techniques, such as methyl esterification and chelation to zinc, both increase the sensitivity of analyses and provide spectroscopic signatures that enable heme/cyclic tetrapyrrole ions to be identified in the presence of contaminants. Copyright © 2002 John Wiley & Sons, Ltd.
Buffer management and rate guarantees for TCP over satellite‐ATM networks
Authors: Goyal Rohit , Jain Raj , Goyal Mukul , Fahmy Sonia , Vandalore Bobby , Kota Sastri , Butts Norm , vonDeak Thomas
Published: August 2002

Future broadband satellite networks will support a variety of service types. Many such systems are being design with ATM or ATM‐like technology. A majority of Internet applications use TCP for data transfer. As a result, these systems must efficiently transport TCP traffic and provide service guarantees to such traffic. Several mechanisms have been presented in recent literature to improve TCP performance. Most of these can be categorized as either TCP enhancements or network‐based buffer management techniques. Providing minimum rate guarantees to TCP traffic has also been suggested as a way to improve its performance in the presence of higher priority traffic sharing the link. However, the relative performance of the TCP enhancements versus the buffer management schemes has not been analyzed for long latency networks. In this paper, we address three issues. First, we present a performance analysis of TCP over satellite‐ATM links using a best effort service—the ATM unspecified bit rate (UBR) service. This analysis shows that the relative impacts of buffer management, TCP policies and rate guarantees on TCP performance, depend heavily on the latency of the network. Second, we show through simulations that the buffer size required in the network for high TCP performance is proportional to the delay‐bandwidth product of the network. Third, we propose a buffer management scheme called differential fair buffer allocation (DFBA) and show how it is used to implement a service that provides minimum rate guarantees to TCP traffic. An example of such a service is the ATM guaranteed frame rate (GFR) service, which is being standardized by the ATM Forum and the ITU. Copyright © 2001 John Wiley & Sons, Ltd.
Prediction of triple‐orbital diversity performance in Earth‐space communication
Authors: Panagopoulos A. D. , Kanellopoulos J. D.
Published: August 2002

Orbital diversity is considered to be an effective technique to overcome large fade margins in satellite communication links. This paper discusses triple‐orbital diversity, which uses three satellites and an Earth receiving site. A method for calculating the outage probability of a triple‐orbital diversity protection scheme is proposed. It is based on a model for convective raincells and the lognormal assumption for point rainfall rate statistics. Numerical results are compared with an available set of experimental data taken from a VSAT Earth‐station located in Japan. The agreement was found to be quite encouraging. Some useful conclusions, concerning the relative advantage of using triple‐ against the double‐orbital diversity scheme are also deduced. Copyright © 2002 John Wiley & Sons, Ltd.
Point and set reasoning in practical science measurement by entering university freshmen
Authors: Lubben Fred , Campbell Bob , Buffler Andy , Allie Saalih
Published: August 2002

The procedural understanding of university students at the freshman level, prior to instruction, has been investigated in the context of experimental work in physics. A written instrument was used to explore students' ideas about data collection, data processing, and data comparison; in particular, the need to repeat measurements and the implications of the scatter associated with numerical and graphical data. Two types of reasoning used by students in the laboratory, viz. point and set reasoning, are proposed and used to classify students' responses. The findings show a high degree of consistency of these modes of reasoning across the experimental phases of data collection and data processing. A framework is suggested from which a laboratory teaching program may be developed. © 2001 John Wiley & Sons, Inc. Sci Ed 85:311–327, 2001.
A Construction Method for Picture Information Having a Recovery Function
Authors: Minami Noriaki , Wakasugi Koichiro , Kasahara Masao , Tazaki Saburo
Published: August 2002

There has been a recent trend for keeping important information on social activities by outputting it as picture information on the paper medium, which goes against the current trend of doing away with paper. Among the methods developed to follow this trend, those in which preserving the high quality of the picture image is desired are numerous. On the other hand, picture information processing is conducted in general from the point of view of information engineering in recovering the characters of ancient books, for example. However, there are limitations in the conventional methods since studies on recovering picture information have not been carried out for these methods. If the state of development of the signal processing technology in recent years is considered, conducting processing that supports the recovery of preserved picture in advance is considered to be most effective. In this paper, from the viewpoint of constructing a forward‐looking picture information system, conducting processing allowing the recovery function for digital picture information output on paper, and so on is proposed and a scheme for realizing it is discussed. In the proposed scheme, the original picture image information can be reproduced from the picture information preserved on paper with erasures. © 2001 Scripta Technica, Syst Comp Jpn, 33(1): 64–76, 2002