bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of isorhamnetin glycosides in extracts of apples (Malus domestica cv. “Brettacher”) by HPLC‐PDA and HPLC‐APCI‐MS/MS
Authors: Schieber Andreas , Keller Petra , Streker Petra , Klaiber Iris , Carle Reinhold
Published: August 2002

Extracts of apple fruits (Malus domestica cv. “Brettacher”) were analysed by HPLC with photodiode array detection. An unknown peak was monitored displaying the same retention time as isorhamnetin 3‐O‐glucoside. Preliminary identification of the isorhamnetin aglycone was performed by comparison of UV spectral data of the unknown compound with a reference substance. Using atmospheric pressure chemical ionisation mass spectrometry in the negative ion mode, the presence of an isorhamnetin glycoside was supported by loss of 162 amu from the pseudomolecular ion (m/z 477). MS2 product ion analysis of the parent ion m/z 477 provided a fragmentation pattern identical to the reference. Collision‐induced dissociation of the aglycone (m/z 315) in the MS3 product ion analysis allowed the differentiation of rhamnetin and isorhamnetin, and unambiguous assignment by comparison with standard compounds. A second isorhamnetin glycoside eluting prior to the glucoside was tentatively identified as isorhamnetin 3‐O‐galactoside. To the best of our knowledge, this is the first report of isorhamnetin glycosides in apple fruit extracts. Results are discussed with respect to chemotaxonomic relevance within the genera Malus and Pyrus, and especially in consideration of the control of the authenticity of apple products. Copyright © 2002 John Wiley & Sons, Ltd.
Second trimester maternal serum analytes in triploid pregnancies: correlation with phenotype and sex chromosome complement
Authors: Benn Peter A. , Gainey Andrea , Ingardia Charles J. , Rodis John F. , Egan James F. X.
Published: August 2002

Second trimester maternal serum alpha‐fetoprotein (MS‐AFP), human chorionic gonadotrophin (hCG), unconjugated estiol (uE3), and inhibin‐A (INH‐A) levels were evaluated in pregnancies complicated by triploidy. In addition to seven new triploid pregnancies, the results for 67 published cases were reviewed. All cases appear to fall into two major groups. First, those identifiable as screen‐positive for both Down syndrome and an open neural tube defect (ONTD) with elevated MS‐AFP, grossly elevated hCG, low/normal uE3, and probably elevated INH‐A. Pregnancies in the second group are identifiable as screen‐positive for trisomy 18 with low/normal MS‐AFP, and very low hCG, uE3 and INH‐A. Triploid pregnancies with high maternal serum hCG nearly always show a placenta with partial mole (25/27 or 93%), a high frequency of ONTDs or ventral wall defects (VWDs) (8/28 or 29%) and have either an XXX or XXY karyotype (observed ratio 6:10, respectively). Low hCG is infrequently associated with a molar placenta (1/11 or 9%), does not appear to be associated with ONTDs or VWDs (0/29 or 0%), and shows an excess of XXX over XXY karyotypes (observed ratio 17:2). There were 16 cases with either a molar placenta, an ONTD or a VWD that received the MS‐AFP and hCG tests. All 16 were screen‐positive for an ONTD (MS‐AFP≥2 multiples of the median). In addition, all 31 cases that received MS‐AFP, hCG, uE3 (and where available INH‐A) were screen‐positive for either Down syndrome or trisomy 18. The findings are discussed in the context of expected differences between digynic and diandric triploidy. It is suggested that the sex chromosome complement in triploidy is an important factor in determining risk for partial mole development and in utero survival. Copyright © 2001 John Wiley & Sons, Ltd.
Prenatal diagnosis of NADH:ubiquinone oxidoreductase deficiency
Authors: Niers L. E. M. , Smeitink J. A. M. , Trijbels J. M. F. , Sengers R. C. A. , Janssen A. J. M. , van den Heuvel L. P.
Published: August 2002

NADH:ubiquinone oxidoreductase (complex I of the mitochondrial respiratory chain) deficiency is a severe disorder with an often early fatal outcome. Prenatal diagnosis for complex I defects currently relies mainly on biochemical assays of complex I in fetal tissues such as chorionic villi (CV), and is only in a minority of cases possible by means of mutational analysis of nuclear‐encoded genes of complex I. We report on our experience to date with prenatal diagnosis in pregnancies at risk for complex I deficiency. We measured complex I activity in native CV and/or cultured CV in 23 pregnancies in 15 families. In accordance with the results of the investigations in CV, 15 children were born clinically unaffected. Two prenatally diagnosed unaffected fetuses and two prenatally diagnosed affected fetuses were lost prematurely with spontaneous or provoked abortions, respectively. Two affected children were born (prenatally found to be affected). In two pregnancies a discrepancy between native and cultured cells was found. We conclude that prenatal diagnosis for complex I deficiency can be reliably performed. Pitfalls were encountered in using cultured CV as a result of maternal cell contamination (MCC). Future research on pathogenic nuclear mutations underlying complex I deficiency will extend the possibilities for prenatal diagnosis at the molecular level. Copyright © 2001 John Wiley & Sons, Ltd.
Postnatal investigation of fetal renal disease
Authors: de Bruyn Rose , Gordon Isky
Published: August 2002

The antenatal ultrasound diagnosis of renal tract abnormalities is now firmly established. Postnatal imaging protocols are constantly evolving and still many questions remain unanswered. Most infants are asymptomatic at birth and aggressive imaging is unwarranted both for the infant and overburdened Radiology departments. The urgency with which to undertake imaging relates to the suspected antenatal diagnosis and clinical scenario, with bilateral hydronephrosis, posterior urethral valves and complicated duplex systems taking a high priority. The main imaging modality postnatally remains ultrasound, and together with nuclear medicine gives a powerful combination of both anatomy and function. Intravenous urography is never indicated in the neonate. Copyright © 2001 John Wiley & Sons, Ltd.
Intrauterine rescue transfusion in monochorionic multiple pregnancies with recent single intrauterine death
Authors: Tanawattanacharoen Somchai , Taylor Myles J. O. , Letsky Elizabeth A. , Cox Phil M. , Cowan Frances M. , Fisk Nicholas M.
Published: August 2002

To assess the role of fetal blood sampling and intrauterine transfusion in monochorionic (MC) multiple pregnancy complicated by single intrauterine death (IUD), we reviewed ten cases over a 4‐year period in a tertiary referral centre which underwent fetal blood sampling within 24 h of death of its MC co‐twin. Intrauterine rescue transfusion was performed in all seven anaemic fetuses (hematocrit; Hct<30%) to raise the fetal Hct to ≥40%. The rationale was to prevent death and/or brain injury. Two fetuses, which were severely acidaemic at blood sampling, died in utero within 24 h of the procedure. In two cases, the surviving twins manifested abnormal sonographic findings of the fetal brain 2–5 weeks later and underwent late termination. In two cases, the pregnancies continued uneventfully until delivery at 35 and 40 weeks' gestation with good neonatal outcome. In one case the co‐twin delivered 1 week later at 29 weeks but died within 12 h. Fetuses without anaemia were not transfused and had normal clinical outcomes. We suggest that intrauterine rescue transfusion before the development of severe acidaemia in anaemic surviving MC co‐twins may prevent fetal death, but does not necessarily prevent brain injury. Until its role becomes clearer, we recommend that its use be restricted to situations in which the parents and the local jurisdiction allow late termination as an option if brain injury subsequently manifests on ultrasound. Copyright © 2001 John Wiley & Sons, Ltd.
The second injection technique event (SITE), May 2000, Barcelona, Spain
Authors: Strauss Kenneth , Gols Heidi De , Letondeur Corinne , Matyjaszczyk Marc , Frid Anders
Published: August 2002

Diabetes nurses and observant patients have long known that the technique of injection is critical to the successful use of insulin, but the medical community at large and most insulin‐injecting patients remain unaware of the hows and whys of proper technique. The Second Injection Technique Workshop, held in Barcelona, brought together over 90 injection experts from across Europe and the world. This paper highlights major findings in this emerging field as well as practical guidelines and recommendations. Epidemiologic findings on current injection practice are presented and areas meriting future study are outlined. Copyright © 2002 John Wiley & Sons, Ltd.
Surgical treatment of obesity and its co‐morbidities
Authors: Dachtler Jenny , Johnston David
Published: August 2002

The obesity epidemic now affects children and adolescents as well as 20% of adult Britons. Though some recently introduced drugs seem promising, the epidemic has thus far proved impervious to all attempts at controlling it, and the prevalence of the disease has tripled in the past 25 years. All obesity (BMI > 30) should be regarded as ‘morbid’, as it is associated with an increased risk of cardiovascular disease, type 2 diabetes, cancer and premature death. So‐called ‘morbid obesity’ (BMI > 40) represents an extreme form of the disease – almost double ideal weight – and it is not logical to delay treatment, whether medical or surgical, until this stage has been reached. Naturally, all conservative strategies should be exhausted before surgical treatment is contemplated, but if 1–3 years of intensive medical treatment prove unsuccessful, effective surgical treatment should not be too long delayed, otherwise irreversible pathological changes may develop in blood vessels, eyes, kidneys and elsewhere, while social, emotional and economic troubles may wreck young lives. The various surgical procedures used today in the treatment of obesity all limit intake, and some also impair absorption. Many are now performed laparoscopically, with the expected advantages of shorter hospital stay and fewer complications. While by no means devoid of side effects, modern operative procedures for obesity are much more successful than the old ‘gastric stapling’ or jejuno‐ileal bypass procedures. Mortality and post‐operative morbidity are both very low, weight loss averages about 30% of pre‐operative weight 1–2 years after operation, and this loss is maintained in most patients. Most patients who are hypertensive or have impaired glucose tolerance before operation return to normal after operation, and normal glucose tolerance is also restored in approximately 80% of patients with type 2 diabetes, for periods of up to 14 years. Patients report improvements in quality of life, self‐esteem and mood. Copyright © 2002 John Wiley & Sons, Ltd.
Radical thermo‐ and sonopolymerization of methyl methacrylate initiated by iodobenzene 1,1‐diacetate
Authors: Georgiev George S , Kamenska Elena B , Tsarevsky Nikolay V , Christov Latchezar K
Published: August 2002

The efficiency of iodobenzene 1,1‐diacetate or (diacetoxyiodo)benzene (DAIB) as a thermo‐ and sono‐initiator of methyl methacrylate (MMA) in radical bulk polymerization is tested. The polymerization kinetics and molecular‐mass characteristics support an assumption for a combined polymerization mechanism including a classical bimolecular termination with chain transfer reaction and iniferter quasi‐living polymerization. In addition to the equilibrium formation and degradation of the ‘dormant’ polymer ends, other possible decomposition reactions of the hypervalent iodine bond are the probable reason for the deviation of this polymerization from the iniferter polymerization mechanism. These reactions bear some similarity to the two‐step addition–fragmentation chain transfer mechanism of controlled radical polymerization. The application of the poly(MMA) obtained as a macroinitiator is evidence of ‘dormant’ chain end formation.

© 2001 Society of Chemical Industry
Synthesis and characterization of new biodegradable fluorescing poly(amide‐anhydrides)
Authors: Jiang H L , Zhu K J , Dai L J
Published: August 2002

Biodegradable/alternate/poly(amide‐anhydrides), [C(O)PhNHC(O)(CH2)
nC(O)O]
x, were synthesized by melt polycondensation, where n was 2, 3 or 4. The polymers have been characterized by NMR, DSC, wide‐angle X‐ray diffractometry and fluorometry. All the polymers are amorphous and their Tg ranges from 60 to 80 °C. Poly(p‐(carboxyethylformamido)benzoic anhydride) (PCEFB) as a film or in solution in chloroform can emit strong fluorescence, which was not observed for the other two polyanhydrides (n  = 3, 4). The maximum emission wavelength varies with the excitation wavelength, 480 and 520 nm at the excitation wavelength of 470 nm, and 430 nm at 356 nm. In addition, the fluorescence intensities increase linearly with the molecular weight of PCEFB. Such inherent fluorescing properties of PCEFB, together with its biodegradability, make the polymer a potential visible matrix for drug delivery.

© 2001 Society of Chemical Industry
Benzoyl peroxide–p‐acetylbenzylidenetriphenyl arsoniumylide initiated copolymerization of citronellol and styrene
Authors: Srivastava A K , Pandey Prachi
Published: August 2002

Alternating copolymers, containing styrene and citronellol sequences, have been synthesized by radical polymerization using benzoylperoxide (BPO)–p‐acetylbenzylidenetriphenyl arsoniumylide (pABTAY) as initiator, in xylene at 80 ± 1 °C for 3 h under inert atmosphere. The kinetic expression is Rp ∝ [BPO]0.88 [citronellol]0.68 [styrene]0.56 with BPO and Rp ∝ [pABTAY]0.27 [citronellol]0.76 [styrene]0.63 with pABTAY, ie the system follows non‐ideal kinetics in both cases, because of primary radical termination and degradative chain transfer reactions. The activation energy with BPO and pABTAY is 94 kJ mol−1 and 134 kJ mol−1, respectively. Different spectral techniques, such as IR, FTIR, 1H NMR and 13C NMR, have been used to characterize the copolymer, demonstrating the presence of alcoholic and phenyl groups of citronellol and styrene. The alternating nature of the copolymer is shown by the product of reactivity ratios r1 (Sty) = 0.81 and r2 (Citro) = 0.015 using BPO and r1 (Sty) = 0.37 and r2 (Citro) = 0.01 using (pABTAY), which are calculated by the Finemann–Ross method. A mechanism of copolymerization is proposed.

© 2001 Society of Chemical Industry
Polymerization and characterization of various di(pyridine)bis(trihalophenolato)cobalt(II) complexes in solid and melt states
Authors: Kesici Neslin , Kısakürek Duygu
Published: August 2002

The syntheses of distorted tetrahedral bis(pyridine)bis(trihalophenolato)cobalt(II) complexes from an aqueus solution were achieved and their characterization by FT‐IR, X‐ray, DSC, UV‐visible and elemental analysis in solid state or in melt form is reported. Polymerizations of these complexes were accomplished either at constant temperature, employing different time intervals or constant decomposition times while varying the temperature range. The slow decomposition at constant temperature leads to long chain products, whereas long chains formed at higher temperatures were during a constant time. The resulting poly(dihalophenylene oxide)s were characterized by FT‐IR, 1H NMR, 13C NMR spectral analysis, differential scanning calorimetry and molecular weight determinations by viscometric method.

© 2001 Society of Chemical Industry
Synthesis and characterization of polyelectrolyte hydrogels with controlled swelling behaviour
Authors: Atta Ayman M , Arndt Karl F
Published: August 2002

Copolymerization of sulfopropyl methacrylate potassium salt (K‐SPMA) and 2‐acrylamido‐2‐methyl propane sulfonic acid (AMPS) has been studied in the range 10–90% K‐SPMA in the feedstock. The reactivity ratios have been determined for K‐SPMA/AMPS copolymers. The copolymer compositions, utilized for determining the reactivity ratio, have been determined from nitrogen content. Crosslinked poly(AMPS) and K‐SPMA/AMPS copolymers were prepared in water in the presence of potassium persulfate as initiator and N,N‐methylene bisacrylamide (MBA) as tetrafunctional crosslinker. Irradiation of K‐SPMA and AMPS with an electron‐beam was carried out at 50 wt% aqueous solution with low pH and irradiation dose 40–120 kGy. The swelling behaviour of highly crosslinked K‐SPMA/AMPS copolymer polyelectrolyte gels in aqueous medium was studied in the presence of different types of salts. The crosslink density, the average molecular weight between the crosslinks and the dissociation constant (pKa) of the crosslinked polymer were determined from stress–strain measurements.

© 2001 Society of Chemical Industry
Formation and behaviour of low‐temperature melting peak of quenched and annealed isotactic polypropylene
Authors: Dudić Dus̆ke , Kostoski Dus̆an , Djoković Vladimir , Dramićanin Miroslav D
Published: August 2002

The process of low‐melting point (LMP) α‐phase formation in a quenched and annealed isotactic polypropylene (iPP) was studied by means of differential scanning calorimetry. The influence of preparation conditions (quenching and annealing temperatures, annealing times and sample thickness), together with the measurement parameters (heating and cooling rates), on the iPP melting behaviour are analysed. The results reveal a constant yield of LMP crystals over a wide range of quenching temperatures. This study also suggests that the LMP α‐crystals originate from the crystallization of polymer portions, which are somewhere between the amorphous and the smectic phase on the macromolecular scale of order.

© 2001 Society of Chemical Industry
Predicting school weapon possession: A secondary analysis of the youth risk behavior surveillance survey
Authors: Furlong Michael J. , Bates Michael P. , Smith Douglas C.
Published: August 2002

As school psychologists are asked to help schools evaluate the level of violence risk posed by specific students, they need to fully consider the technical adequacy of any test or procedure that is proposed to “predict” future violent behavior or conditions. In this article, we contribute to this discussion by examining responses of 40,435 students from the 1993, 1995, and 1997 administrations of the Youth Risk Behavior Surveillance Survey. Student self‐reported school risk behaviors and experiences are used to “predict” recent weapon possession on school campuses and to illustrate the use of receiver operating characteristic curves to evaluate the performance of a test for prediction purposes. An index of nine school risk behaviors was moderately correlated (r = .36) with school weapon possession. However, when the accuracy of using this school risk index to predict weapon possession is evaluated, it is found that the area under the ROC curve was approximately .75, a moderate‐to‐large effect size but still demonstrating inadequate prediction at the individual student level. Further, there were twice as many frequent weapon carriers with zero school risks than with 7–9 risks, suggesting that attention directed toward violence risk profiles may promote inattention to another group of students who engage in potentially high‐risk behaviors at school. It is argued that school psychologists should consider school violence appraisals within a developmental, long‐term model. © 2001 John Wiley & Sons, Inc.
Molecular geometry and electronic structure of molecules in free‐radical copolymerization of styrene and methyl methacrylate derived from density functional calculations
Authors: Megiel Elżbieta , Kaim Andrzej
Published: August 2002

The molecular geometry and electronic structure of styrene and methyl methacrylate as well as corresponding radicals formed by the addition of a methyl radical to the β‐carbon of the monomer were determined using the density functional theory at the B3LYP/6‐311+G** level. Results were in good agreement with the theoretical and experimental data available in the literature. Full optimized molecular geometry of methyl methacrylate showed the trans form of the molecule. Monomers transformed into corresponding radicals preserved the main structural parameters of substituents whereas bonds between substituents and adjacent radical carbon atoms shortened. It was found that the correlation of the theoretically calculated electronic parameters for monomers and the corresponding radicals with the Q and e parameters from the Alfrey–Price scheme strongly depends on the level of calculations. Application of the higher level of theory including the correlation effect changes the relationship discussed in the literature between energy (EY) of formation of a radical from the monomer, the experimental e parameter, and the Q parameter and monomer/average electronegativity, respectively. The total atomic spin density at the radical carbon atom correlated with the radical parameter P in the Alfrey–Price scheme was computed to be higher for the methoxycarbonyl‐1‐methyl‐ethyl radical when compared with the 1‐phenyl‐propyl radical. These values are in good agreement with the localization energies and the P values determined from the kinetic measurements for macroradicals ending with styrene and methyl methacrylate monomer units. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3761–3769, 2001
Long‐chain‐branched polyethene by the copolymerization of ethene and nonconjugated α,ω‐dienes
Authors: Kokko Esa , Pietikäinen Pirjo , Koivunen Jari , Seppälä Jukka V.
Published: August 2002

Ethene was copolymerized (1) with 1,5‐hexadiene with rac‐ethylenebis(indenyl)zirconium dichloride/methylaluminoxane (MAO) used as a catalyst and (2) with 1,7‐octadiene with bis(n‐butylcyclopentadienyl)zirconium dichloride/MAO and rac‐ethylenebis(indenyl)hafnium dichloride (Et[Ind]2HfCl2)/MAO used as catalysts at 80 °C in toluene. The copolymer microstructure and the influence of diene incorporation on the rheological properties were examined. Ethene and 1,5‐hexadiene formed a copolymer in which a major fraction of the 1,5‐hexadiene was incorporated into rings and a small fraction formed 1‐butenyl branches. The copolymerization of ethene with 1,7‐octadiene resulted in a higher selectivity toward branch formation. Some of the branches formed long‐chain‐branching (LCB) structures. The ring formation selectivity increased with decreasing ethene concentration in the polymerization reactor. Melt rheological properties of the diene copolymers resembled those of metallocene‐catalyzed LCB homopolyethenes and depended on the vinyl content, the catalyst, and the polymerization conditions. At high diene contents, all three catalysts produced crosslinked polyethene. This was especially pronounced with Et[Ind]2HfCl2, where only 0.2 mol % 1,7‐octadiene in the copolymer was required to achieve significantly modified rheological properties. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3805–3817, 2001
Application of novel polymers with S‐alkylsulfonium salt moieties as alkylating agents and thermal latent cationic initiators
Authors: Shimomura Osamu , Tomita Ikuyoshi , Endo Takeshi
Published: August 2002

Sulfonium‐containing polymers prepared from dibenzothiophene and diphenyl sulfide were applied as both alkylating agents and latent initiators for the cationic polymerization of glycidyl phenyl ether. The alkylation of acetonitrile proceeded smoothly with poly(S‐n‐octyl‐2‐vinyldibenzothiophenium tetrafluoroborate) (4; 64 mol % octyldibenzothiophenium tetrafluoroborate unit) to give N‐(n‐octyl)acetamide in an excellent yield on the basis of the starting octyldibenzothiophenium tetrafluoroborate unit in 4. The cationic polymerization of glycidyl phenyl ether was also carried out in the presence of poly(S‐methyl‐2‐vinyldibenzothiophenium tetrafluoroborate) or poly(S‐n‐octyl‐4‐vinyldiphenylsulfonium tetrafluoroborate) to confirm their moderate thermal latent activity. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3928–3933, 2001
Amphiphilic diblock, triblock, and star block copolymers by living radical polymerization: Synthesis and aggregation behavior
Authors: Narrainen Amilcar Pillay , Pascual Sagrario , Haddleton David M.
Published: August 2002

Copper(I)‐mediated living radical polymerization was used to synthesize amphiphilic block copolymers of poly(n‐butyl methacrylate) [P(n‐BMA)] and poly[(2‐dimethylamino)ethyl methacrylate] (PDMAEMA). Functionalized bromo P(n‐BMA) macroinitiators were prepared from monofunctional, difunctional, and trifunctional initiators: 2‐bromo‐2‐methylpropionic acid 4‐methoxyphenyl ester, 1,4‐(2′‐bromo‐2′‐methyl‐propionate)benzene, and 1,3,5‐(2′‐bromo‐2′‐methylpropionato)benzene. The living nature of the polymerizations involved was investigated in each case, leading to narrow‐polydispersity polymers for which the number‐average molecular weight increased fairly linearly with time with good first‐order kinetics in the monomer. These macroinitiators were subsequently used for the polymerization of (2‐dimethylamino)ethyl methacrylate to obtain well‐defined [P(n‐BMA)x‐b‐PDMAEMAy]z diblock (15,900; polydispersity index = 1.60), triblock (23,200; polydispersity index = 1.24), and star block copolymers (50,700; polydispersity index = 1.46). Amphiphilic block copolymers contained between 60 and 80 mol % hydrophilic PDMAEMA blocks to solubilize them in water. The polymers were quaternized with methyl iodide to render them even more hydrophilic. The aggregation behavior of these copolymers was investigated with fluorescence spectroscopy and dynamic light scattering. For blocks of similar comonomer compositions, the apparent critical aggregation concentration (cac = 3.22–7.13 × 10−3 g L−1) and the aggregate size (ca. 65 nm) were both dependent on the copolymer architecture. However, for the same copolymer structure, increasing the hydrophilic PDMAEMA block length had little effect on the cac but resulted in a change in the aggregate size. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 439–450, 2002; DOI 10.1002/pola.10122
Polyterephthalamides with naphthoxy‐pendent groups
Authors: Liou Guey‐Sheng , Hsiao Sheng‐Huei
Published: August 2002

A series of new aromatic polyamides having pendent naphthoxy groups were synthesized by the triphenyl phosphite‐activated polycondensation of (2‐naphthoxy)terephthalic acid (NOTPA) with various aromatic diamines in a medium consisting of N‐methyl‐2‐pyrrolidone (NMP), pyridine, and calcium chloride. The diacid monomer NOTPA was prepared from the nitro displacement of dimethyl 2‐nitroterephthalate with the potassium naphthoxide of β‐naphthol, followed by base‐induced ester hydrolysis. All the resulting polymers were noncrystalline and readily soluble in aprotic polar solvents such as NMP and N,N‐dimethylacetamide. Almost all the polymers could be solution‐cast to tough, creasable amorphous films with good mechanical properties, the values of tensile strengths ranging from 90 to 124 MPa with initial moduli ranging from 1.72 to 2.51 GPa. Except for two examples, all the other polyamides displayed discernible glass transitions between 189 and 248 °C in the differential scanning calorimetric traces. These polyamides showed insignificant decomposition below 400 °C in nitrogen or air. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1781–1789, 2002
Synthesis and characterization of rigid‐chain liquid–crystalline polymers containing laterally attached side rods
Authors: Zhao Lun , He Chaobin , Lu Zhihua , Chung T. S.
Published: August 2002

A series of rigid‐chain polymers containing different concentrations of laterally attached side rods was synthesized. These polymers exhibited liquid crystallinity even up to a maximum side rod concentration of 20 mol %. The crystallinity of the polymers, however, decreased with an increase in the side‐rod concentration. These polymers had lower dielectric constants compared with their parent polymers, that is, similar polymers, but without laterally attached side rods. A dielectric constant of 2.6 can be achieved by incorporating 10 mol % of laterally attached side rods, which is 0.5 lower than that of its parent polymer. The reduction of dielectric constant may be attributed to low crystallinity as well as the less dense packing structure of the polymers induced by the incorporation of laterally attached side rods. This series of polymers also had good thermal stability. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1288–1294, 2001
Synthesis of high molecular weight trans‐poly(9,9‐di‐n‐octylfluorene‐2,7‐vinylene) by the acyclic diene metathesis polymerization using molybdenum catalysts
Authors: Nomura Kotohiro , Morimoto Hisao , Imanishi Yukio , Ramhani Zoubir , Geerts Yves
Published: August 2002

High molecular weight trans‐poly(9,9‐di‐n‐octylfluorene‐2,7‐vinylene) was prepared under reduced pressure in the presence of a well‐defined Schrock‐type catalyst, Mo(CHCMe2Ph)(N‐2,6‐Me2C6H3)[OCMe(CF3)2]2, in toluene. The effect of initial monomer concentration was found to be an important factor for preparing high molecular weight polymers with unimodal molecular weight distributions. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2463–2470, 2001
Synthesis of an amphiphilic styrenic block copolymer: Polycondensation of dichloromethane and low molecular weight poly(ethylene glycol) in the presence of hydroxypropylated polystyrene‐block‐polybutadiene
Authors: Shen Guang‐Min , Chen Chien‐Chih , Tsiang Raymond Chien‐Chao
Published: August 2002

An amphiphilic styrenic block copolymer, polystyrene‐block‐polybutadiene‐block‐poly[oxymethylene‐alt‐oligo(oxyethylene)] (PS‐b‐PB‐b‐POME), was synthesized through a polycondensation reaction of low molecular weight poly(ethylene glycol) and dichloromethane in the presence of hydroxypropylated polystyrene‐block‐polybutadiene (PS‐b‐PB‐OH) used as a monofunctional chain‐capping reagent. PS‐b‐PB‐OH was in turn prepared via an anionic synthesis of PS‐b‐PB followed by oxetane capping and methanol quenching. Although PS‐b‐PB‐OH has insignificant hydrophilicity, PS‐b‐PB‐b‐POME containing both the hydrophobic PS‐b‐PB segment and the hydrophilic POME segment had an improved emulsifying capability and effectively decreased the interfacial tension between water and toluene. The hydrophile–lipophile balance value of this amphiphilic PS‐b‐PB‐b‐POME copolymer, consisting of 86 wt % of the POME segment and 14 wt % of the PS‐b‐PB segment, was 17.2. The molecular weight of the copolymer molecule was determined by gel permeation chromatography–multi‐angle laser light scattering, and the microstructure was analyzed using 1H NMR. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2625–2632, 2001
Hyperbranched polymers from propargyloxysilanes: New types of acetylenic resins
Authors: Xiao Yingxin , Son David Y.
Published: August 2002

New hyperbranched polymers (1P–3P) from propargyloxysilanes (1–3) are described. The propargyloxysilanes were prepared from readily available reagents in 53–61% yields. The polymerizations were clean, one‐pot hydrosilylation processes catalyzed by Pt/C that were typically complete within 3 h. The polymers contained pendant acetylenic groups that underwent thermally induced crosslinking reactions. Heating the polymers to 1300 °C in flowing nitrogen resulted in weight losses ranging from 33 to 66%. Methyl substitution resulted in lower thermal stability. Further modification of the polymers was demonstrated by the reaction of 1P and 2P with phenylethynyldimethylsilane in the presence of a Pt catalyst. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3383–3391, 2001
Mechanics of contact and adhesion between viscoelastic spheres: An analysis of hysteresis during loading and unloading
Authors: Lin Yu‐Yun , Hui C. Y.
Published: August 2002

Detailed finite element simulations are carried out to study the adhesive contact of viscoelastic spheres. The spheres are brought into contact by a compressive force that increases at a constant rate. Upon reaching a maximum load, the spheres are unloaded until they separate. We studied in detail the effect of loading and unloading rates on hysteresis and on the pull‐off force for a standard viscoelastic solid. The surface interaction is modeled by the Dugdale–Barenblatt model. Numerical results are compared with analytical models for bonding and debonding, including a recent theory proposed by Johnson. There is excellent agreement between analytical and finite element results for the bonding phase. However, for the debonding phase, current analytical models break down unless the loading and unloading rates are slow in comparison with the material relaxation time. Based on the finite element results, a simple approximate analytical model is proposed to quantify adhesive contact in the debonding phase. We also examine the dependence of hysteresis on interfacial parameters such as the cohesive strength and the intrinsic work of adhesion. Our results show that viscoelastic adhesive contact depends on the details of the surface interaction and cannot be determined solely by the work of adhesion. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 772–793, 2002
Polydispersity of ethylene sequence length in metallocene ethylene/α‐olefin copolymers. II. Influence on crystallization and melting behavior
Authors: Zhang Fajun , Liu Jieping , Xie Fengchao , Fu Qiang , He Tianbai
Published: August 2002

In this work, crystallization and melting behavior of metallocene ethylene/α‐olefin copolymers were investigated by differential scanning calorimetry (DSC) and atomic force microscopy (AFM). The results indicated that the crystallization and melting temperatures for all the samples were directly related to the long ethylene sequences instead of the average sequence length (ASL), whereas the crystallization enthalpy and crystallinity were directly related to ASL, that is, both parameters decreased with a decreasing ASL. Multiple melting peaks were analyzed by thermal analysis. Three phenomena contributed to the multiple melting behaviors after isothermal crystallization, that is, the melting of crystals formed during quenching, the melting‐recrystallization process, and the coexistence of different crystal morphologies. Two types of crystal morphologies could coexist in samples having a high comonomer content after isothermal crystallization. They were the chain‐folded lamellae formed by long ethylene sequences and the bundlelike crystals formed by short ethylene sequences. The coexistence phenomenon was further proved by the AFM morphological observation. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 822–830, 2002
Structural and dynamic study of chemically modified polyHIPE by solid‐state 13C NMR spectroscopy
Authors: Mercier A. , Kuroki S. , Ando I. , Deleuze H. , Mondain‐Monval O.
Published: August 2002

The structure of laboratory‐made polyHIPEs was successfully characterized by cross‐polarity/magic‐angle spinning, solid‐state 13C NMR experiments. The signals of vinyl groups appeared in the spectrum of the polyHIPE precursor PHCHCH2, which was prepared by the polymerization of the divinylbenzene continuous phase from a highly concentrated reverse emulsion. This material was chemically modified by the regioselective free‐radical addition of thiols to the pendant vinyl groups. Spectra of materials modified by the grafting of C8 and C12 alkyl chains, PHSC8 and PHSC12, respectively, were produced. The signals of the vinyl groups disappeared in favor of methylene groups. This experiment clearly established that the alkyl chains were covalently bound to the polymer. To elucidate the dynamic aspect of long chains in polyHIPE, we measured the 13C spin–lattice relaxation times (T1) of PHSC12 from 25 to 100 °C with variable‐temperature, solid‐state, high‐resolution 13C NMR spectroscopy, revealing a strong variation in T1 along the alkyl side chain. Furthermore, the crystallinity of a wide range of chemically modified polyHIPEs, including PHSC12, was studied with pulse 1H NMR. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 956–963, 2001
Entanglement friction and dynamics in blends of starlike and linear polymer molecules
Authors: Lee Jung Hun , Archer Lynden A.
Published: August 2002

We investigate relaxation dynamics in a series of six‐arm star/linear 1,4‐polybutadiene blends with mechanical rheometry measurements. Blend systems are formulated to systematically probe constraint release and arm relaxation dynamics. Zero shear viscosity and terminal relaxation times of star/linear polymer blends with fixed star arm molecular weights (Ma) and compositions (ϕS) are found to follow nonmonotonic dependencies on the linear polymer molecular weight (ML). At low values of ϕS, at least two scaling regimes are apparent from the data (ξ0 ∼ M and ξ0 ∼ M), where ξ0 refers to the zero shear viscosity or terminal relaxation time of the blend. The two regimes are separated by a critical linear polymer molecular weight M* that is more than 20 times larger than the critical molecular weight for entanglements. When the linear polymer contribution to blend properties is removed, a clear transition from dilution dynamics, ξ0 ∼ M, to Rouse‐like constraint‐release dynamics, ξ0 ∼ M, is apparent at low values of ϕS. At higher ϕS values, a new activated constraint‐release dynamic regime is evident in which ξ0 ∼ M and ξ0 ∼ ϕ, where α changes continuously from approximately 2 to 0.5 as ϕS increases and β varies from 2.0 to 1.0 as ML increases. The experimental results are compared with theoretical predictions based on a drag coupling model for entangled polymer liquids. All features observed experimentally are captured by this model, including the value of M* for the transition from dilution to Rouse constraint‐release dynamics. Predictions of the drag coupling model are also compared with published data for the zero shear viscosity and terminal relaxation time in bidisperse linear polymer blends and pure entangled starlike molecules. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2501–2518, 2001
Hypersensitivity to inhaled TOBI® following reaction to gentamicin
Authors: Spigarelli Michael G. , Hurwitz Martin E. , Nasr Samya Z.
Published: August 2002

Cystic fibrosis (CF) is the most common autosomal‐recessive disease in Caucasians. Colonization with Pseudomonas aeruginosa (P. aeruginosa) of the CF airways causes deterioration of pulmonary status. TOBI® (Tobramycin solution for inhalation) is an inhaled antibiotic that can improve the pulmonary disease.

We report on a 9‐year old boy with CF who developed a rash following a course of IV gentamicin. The rash resolved after its discontinuation. However, the rash returned all over his body, with the start of inhalation of TOBI® therapy. We desensitized the patient using escalating doses of inhaled TOBI®. He tolerated the procedure well, and continues to be on TOBI® 9 months after desensitization on a once‐a‐day regimen. Pediatr Pulmonol. 2002; 33:311‐314. © 2002 Wiley‐Liss, Inc.
Expression profiles of voltage‐gated Na+ channel α‐subunit genes in rat and human prostate cancer cell lines
Authors: Diss James K.J. , Archer Simon N. , Hirano Joe , Fraser Scott P. , Djamgoz Mustafa B.A.
Published: August 2002

Background

Voltage‐gated Na+ channel (VGSC) activity has been implicated in prostate cancer (PC) metastasis. Although VGSCs can occur as multiple‐subunit assemblies, the α‐subunits (VGSCαs) alone can encode functional channels. The VGSCα gene(s) responsible for the functional VGSCα expression in strongly metastatic PC cell lines is not known.

Methods

Two reverse transcription‐PCR (RT‐PCR) methods, degenerate primer screening and a novel semi quantitative PCR (SQT‐PCR) technique, were used. These methods enabled a detailed qualitative and quantitative investigation of VGSCα mRNA expression in rat (MAT‐LyLu/AT‐2) and human (PC‐3/LNCaP) PC cells of markedly different metastatic potential.

Results

Expression of eight different VGSCα genes (SCN1A‐4A, SCN7A‐9A, and SCN11A) was determined in the PC cell lines. Most were expressed as multiple splice variants. SQT‐PCR results were consistent with a basal level of VGSCα mRNA expression occurring in weakly metastatic (AT‐2/LNCaP) cells, and this being greatly elevated in cells of stronger metastatic potential (MAT‐LyLu/PC‐3), primarily due to the elevated expression of the SCN9A gene (also termed PN1/hNe‐Na).

Conclusions

(1) Several VGSCα genes and their splice variants are expressed similarly in both rat and human PC cell lines. (2) Expression levels are much higher in the strongly metastatic (MAT‐LyLu/PC‐3) cells. (3) Levels of SCN9A mRNA specifically are predominant in MAT‐LyLu and PC‐3 cells; thus, SCN9A is highly likely to be the main source of the functional VGSC detected. Prostate 48:165–178, 2001. © 2001 Wiley‐Liss, Inc.
Docking multiple conformations of a flexible ligand into a protein binding site using NMR restraints
Authors: Zabell Adam P.R. , Post Carol Beth
Published: August 2002

A method is described for docking a large, flexible ligand using intra‐ligand conformational restraints from exchange‐transferred NOE (etNOE) data. Numerous conformations of the ligand are generated in isolation, and a subset of representative conformations is selected. A crude model of the protein–ligand complex is used as a template for overlaying the selected ligand structures, and each complex is conformationally relaxed by molecular mechanics to optimize the interaction. Finally, the complexes were assessed for structural quality. Alternative approaches are described for the three steps of the method: generation of the initial docking template; selection of a subset of ligand conformations; and conformational sampling of the complex. The template is generated either by manual docking using interactive graphics or by a computational grid‐based search of the binding site. A subset of conformations from the total number of peptides calculated in isolation is selected based on either low energy and satisfaction of the etNOE restraints, or a cluster analysis of the full set. To optimize the interactions in the complex, either a restrained Monte Carlo‐energy minimization (MCM) protocol or a restrained simulated annealing (SA) protocol were used. This work produced 53 initial complexes of which 8 were assessed in detail. With the etNOE conformational restraints, all of the approaches provide reasonable models. The grid‐based approach to generate an initial docking template allows a large volume to be sampled, and as a result, two distinct binding modes were identified for a fifteen‐residue peptide binding to an enzyme active site. Proteins 2002;46:295–307. © 2002 Wiley‐Liss, Inc.
Influence of rotational energy barriers to the conformational search of protein loops in molecular dynamics and ranking the conformations
Authors: Tappura Kirsi
Published: August 2002

An adjustable‐barrier dihedral angle potential was added as an extension to a novel, previously presented soft‐core potential to study its contribution to the effectivity of the search of the conformational space in molecular dynamics. As opposed to the conventional soft‐core potential functions, the leading principle in the design of the new soft‐core potential, as well as of its extension, the soft‐core and adjustable‐barrier dihedral angle (SCADA) potential (referred as the SCADA potential), was to maintain the main equilibrium properties of the original force field. This qualifies the methods for a variety of a priori modeling problems without need for additional restraints typically required with the conventional soft‐core potentials. In the present study, the different potential energy functions are applied to the problem of predicting loop conformations in proteins. Comparison of the performance of the soft‐core and SCADA potential showed that the main hurdles for the efficient sampling of the conformational space of (loops in) proteins are related to the high‐energy barriers caused by the Lennard–Jones and Coulombic energy terms, and not to the rotational barriers, although the conformational search can be further enhanced by lowering the rotational barriers of the dihedral angles. Finally, different evaluation methods were studied and a few promising criteria found to distinguish the near‐native loop conformations from the wrong ones. Proteins 2001;44:167–179. © 2001 Wiley‐Liss, Inc.
Model for the three‐dimensional structure of vitronectin: Predictions for the multi‐domain protein from threading and docking
Authors: Xu Dong , Baburaj Kunnumal , Peterson Cynthia B. , Xu Ying
Published: August 2002

The structure of vitronectin, an adhesive protein that circulates in high concentrations in human plasma, was predicted through a combination of computational methods and experimental approaches. Fold recognition and sequence–structure alignment were performed using the threading program PROSPECT for each of three structural domains, i.e., the N‐terminal somatomedin B domain (residues 1–53), the central region that folds into a four‐bladed β‐propeller domain (residues 131–342), and the C‐terminal heparin‐binding domain (residues 347–459). The atomic structure of each domain was generated using MODELLER, based on the alignment obtained from threading. Docking experiments between the central and C‐terminal domains were conducted using the program GRAMM, with limits on the degrees of freedom from a known inter‐domain disulfide bridge. The docked structure has a large inter‐domain contact surface and defines a putative heparin‐binding groove at the inter‐domain interface. We also docked heparin together with the combined structure of the central and C‐terminal domains, using GRAMM. The predictions from the threading and docking experiments are consistent with experimental data on purified plasma vitronectin pertaining to protease sensitivity, ligand‐binding sites, and buried cysteines. Proteins 2001;44:312–320. © 2001 Wiley‐Liss, Inc.
Analysis of the segmental stability of helical peptides by isotope‐edited infrared spectroscopy
Authors: Venyaminov S. Yu. , Hedstrom J.F. , Prendergast F.G.
Published: August 2002

Isotope‐edited infrared spectroscopy has the ability to probe the segmental properties of long biopolymers. In this work, we have compared the infrared spectra of a model helical peptide (12C) Ac‐W‐(E‐A‐A‐A‐R)6‐A‐NH2, described originally by Merutka et al. (Biochemistry 1991;30:4245–4248) and three derivatives that are 13C labeled at the backbone carbonyl of alanines. The locations of six isotopically labeled alanines are at the N‐terminal, C‐terminal, and the middle two repeating units of the peptide. Variation in temperature from 1° to 91°C transformed the peptides from predominantly helical to predominantly disordered state. Amplitude and position of the infrared amide I′ absorption bands from 12C‐ and 13C‐labeled segments provided information about the helical content. Temperature dependence of infrared spectra was used to estimate segmental stability. As a control measure of overall peptide stability and helicity (independent of labeling), the temperature dependence of circular dichroism spectra in the far‐UV range at identical conditions (temperature and solvent) as infrared spectra was measured. The results indicate that the central quarter of the 32 amino acids helix has the maximal helicity and stability. The midpoint of the melting curve of the central quarter of the helix is 5.4 ± 0.8°C higher than that of the termini. The N‐terminal third of the helix is more helical and is 2.0 ± 1.4°C more stable than the C‐terminus. Proteins 2001;45:81–89. © 2001 Wiley‐Liss, Inc.