bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of neat resins based on methacrylates modified with methacryl‐POSS, as potential organic–Inorganic hybrids for formulating dental restoratives
Authors: Gao Feng , Tong Yuhua , Schricker Scott R. , Culbertson Bill M. 
Published: September 2002

AbstractThree series of neat resins, based on methacrylates or dimethacrylates modified with 1‐[3‐(methacryl)propyl]‐3,5,7,9,11,13,15‐heptacyclopentylpentacyclo[9.5.113,­9.15,15.17,13]octasiloxane (Methacryl‐POSS or POSS‐MA), were evaluated. Incorporation of POSS‐MA into the polymeric matrix was accomplished in three ways: (a) resins series I was formulated with one‐pot copolymerization of a bis‐GMA/diluent monomer with POSS‐MA; (b) the copolymer of 2‐hydroxylethyl methacrylate (HEMA) and POSS‐MA, with a weight ratio of 1 : 1, was first made, then the copolymer hydroxyl groups were converted into methacrylate groups to get a macromer; finally the macromer was copolymerized with bis‐GMA/diluents to formulate the second series of neat resins; (c) copolymer of POSS‐MA and t‐butyl methacrylate (t‐BMA) or 2‐ethylhexyl methacrylate (EHMA) were first made, then they were combined with a mixture of bis‐GMA and the corresponding diluent to make the third kind of neat resins. The amount of POSS incorporated into the neat resin matrix was controlled at 5, 10 and 15 wt%. Incorporating only 5 wt% substantially reduced the shrinkage of the prepared neat resins. The percentage of methacrylate‐functionalized POSS monomer in the bis‐GMA/diluent base, was compared to neat resins prepared without the POSS. The mechanical properties of neat resin having POSS were improved for approaches (b) and (c), but remained at the same level as the neat resins without POSS for approach (a). The results show that miscibility between the POSS component and the matrix, especially the diluent, plays a very important role in the improvement of the properties of the formulated thermosets. Copyright © 2001 John Wiley & Sons, Ltd.
Mechanical properties of interface‐free polyacrylate‐silica hybrid sol–gel materials for potential dental applications
Authors: Wei Yen , Jin Danliang , Xu Jigeng , Baran George , Qiu Kun‐Yuan 
Published: September 2002

AbstractThe mechanical properties of polyacrylate‐silica hybrid sol‐gel materials have been investigated in comparison with conventional resin composites. The hybrid materials with a wide range of silica content were synthesized via the sol–gel reactions of the silica precursor tetraethyl orthosilicate (TEOS) with acrylate copolymers of methyl methacrylate (MMA) with 3‐(trimethoxysilyl)propyl methacrylate (MSMA). In these materials, the polymer chains are uniformly distributed in and covalently bonded to the inorganic silica host matrix at the molecular level without macroscopic organic–inorganic phase separation. The hybrid materials are transparent and non‐porous. In the standard compression test, the hybrid materials exhibited strain hardening behavior which was absent in the conventional PMMA‐silica composites. Their mechanical properties can be fine‐tuned by varying the polyacrylate‐silica composition in the synthesis and are superior over conventional composites at similar silica contents. These hybrid materials are promising for potential dental applications. Copyright © 2001 John Wiley & Sons, Ltd.
Aqueous catalysis by novel macromolecule metal complexes with molecular recognition abilities
Authors: Karakhanov Edward A. , Kardasheva Yulia S. , Maximov Anton L. , Runova Elena A. , Buchneva Tatyana A. , Gaevskiy Mihail A. , Zhuchkova Anna Ya. , Filippova Tatyana Yu. 
Published: September 2002

AbstractA number of water‐soluble macromolecular metal complexes on the basis of polyethers, β‐cyclodextrins, calix[4] and calix[6]arenes functionalized by oligoethylene oxide blocks, catechol, ethylendiamine, acetylacetone, 2,2′‐dipiridyl, phosphines and nitrile containing groups have been developed. Complexes showed high catalytic activity in aqueous hydroformylation, biphasic Wacker‐type oxidation of various higher olefines, alkane oxidation, hydroxylation of benzene and phenol. These catalysts can be multiply reused. The application of host compounds results the extremely selectivities. Copyright © 2001 John Wiley & Sons, Ltd.
Chromogenic polymer gels for reversible transparency and color control with temperature at a constant volume
Authors: Seeboth A. , Kriwanek J. , Lötzsch D. , Patzak A. 
Published: September 2002

AbstractThe preparation and characterization of novel chromogenic materials has developed extremely rapid in the last years. Among them, thermotropic and thermochromic polymer gel networks have met with growing interest, because of their advanced properties. These novel polymer gels exhibit pronounced changes in transparency and/or color intensity in a practically relevant temperature range. For many future technical applications it is an essential condition, that the volume of the used gel materials is independent of temperature. A current overview of this field is given. Copyright © 2002 John Wiley & Sons, Ltd.
Vis‐sensitive photopolymer containing vinyl ether compound and pyrromethene dye
Authors: Noppakundilograt Supaporn , Suzuki Shota , Urano Toshiyuki , Miyagawa Nobukazu , Takahara Shigeru , Yamaoka Tsuguo 
Published: September 2002

AbstractA visible light(vis)‐sensitive photoresist based on the concept of chemical amplification was developed utilizing poly(p‐hydroxystyrene) (PHS), 2,2‐bis[4‐(2‐(vinyloxy)‐ethoxy)phenyl]propane (BPA‐DEVE) as a crosslinking agent, N‐trifluoromethylsulfonyloxy‐1,8‐naphthalimide (NIT) as a photoacid generator (PAG) and pyrromethene dyes such as 1,3,5,7,9‐pentamethylbipyrromethene difluoroborate (PRH) and 2,8‐diethyl‐1,3,5,7,9‐pentamethylbipyrromethene difluoroborate (PRE) and 3,3′‐carbonylbis(7,7′‐diethylaminocoumarin) (KCD). On irradiation with an argon ion laser, the photopolymer comprising PRH and PRE exhibited a high sensitivity of 65 and 46 mJ cm−2, respectively. It is suggested that the sensitization mechanism of the pyrromethene dye/PAG system involves singlet electron transfer. The sensitivity of the photoresist increased with the decreasing molecular weight of PHS because of the high dissolution rate. Copyright © 2002 John Wiley & Sons, Ltd.
Development of an analytical method for the determination of betaines in higher plants by capillary electrophoresis at low pH
Authors: Zhang Jinghua , Nishimura Naoki , Okubo Akira , Yamazaki Sunao 
Published: September 2002

AbstractIn recent years the role of betaines in higher plants has been extensively investigated in relation to environmental stress response. This paper reports the establishment of a simple, rapid and reliable method for the determination of betaines using capillary electrophoresis (CE) at low pH. Betaines were first converted to their phenacyl esters and the crude reaction mixture was then applied directly to CE without any pre‐treatment. Employing an electrolyte running solution at pH 3 gave a well‐resolved electropherogram for the esters of glycine betaine (1), trigonelline, proline betaine, γ‐butyro betaine, and carnitine. The content of 1 and its variation in plant samples collected from high‐salinity areas in north China and west Australia are presented. Copyright © 2002 John Wiley & Sons, Ltd.
Direct analysis of abscisic acid in crude plant extracts by liquid chromatography—electrospray/tandem mass spectrometry
Authors: Gómez‐Cadenas Aurelio , Pozo Oscar J. , García‐Augustín Pilar , Sancho Juan V. 
Published: September 2002

AbstractA new method, based on liquid chromatography–electrospray/tandem mass spectrometry, for the determination of abscisic acid (ABA), an essential plant hormone that regulates key metabolic pathways and responses to environmental cues, has been developed. Substantial changes in extraction procedures are also proposed. Data indicate that the organic solvents classically used as extraction buffers can be substituted by an aqueous solution, resulting in the same amounts of extracted ABA. The new method, which uses minute amounts of plant tissue, has an estimated limit of detection below 50 pmol ABA/g, and the sensitivity of the technique allows the analysis of ABA in crude plant extracts. Overall, this new rapid, sensitive and accurate procedure to determine ABA will allow analysis of multiple samples in a short time and represents a clear advantage in comparison with the conventional procedures involving many preparative steps and large amounts of plant tissue. Copyright © 2002 John Wiley & Sons, Ltd.
Quantitative determination of oleane derivatives in Terminalia arjuna by high performance thin layer chromatography
Authors: Singh D. V. , Verma R. K. , Gupta M. M. , Kumar Sushil 
Published: September 2002

AbstractA simple, precise and rapid high performance thin layer chromatographic method has been developed for the simultaneous quantitative determination of five oleane derivatives, namely, arjunic acid, arjunolic acid, arjungenin, arjunetin and arjunglucoside I from stem bark extract of Terminalia arjuna. The isolation and separation of these compounds was carried out on 60F254 layers eluted with chloroform:methanol (90:10), and the analytes were visualised through colour development with vanillin in concentrated sulphuric acid:ethanol. Scanning and quantification of the spots at 640 nm showed good recoveries in the range 96.40–101.7%. Copyright © 2002 John Wiley & Sons, Ltd.
Determination of andrographolide, deoxyandrographolide and neoandrographolide in the Chinese herb Andrographis paniculata by micellar electrokinetic capillary chromatography
Authors: Zhao Jingxiang , Yang Gengliang , Liu Haixing , Wang Dexian , Song Xiurong , Chen Yi 
Published: September 2002

AbstractIn this paper a micellar electrokinetic capillary chromatographic (MEKC) method has been developed for determining the active components (andrographolide, deoxyandrographolide and neoandrographolide) in water:ethanol extracts of the Chinese crude herb Andrographis paniculata and its preparations (Chuanxinlian and Xiaoyan Lidan tablets). The optimum separation conditions were 15 mM sodium dodecyl sulphate in 30 mM borate buffer (pH 9.5) with UV detection wavelength at 214 nm and a constant voltage of 16 kV. An HPLC method was employed in order to validate the MEKC method with respect to separation efficiency, sensitivity, linearity and repeatability. The two methods are shown to be complementary because of their different selectivity and thus are very suitable for cross‐validation studies. The MEKC method is demonstrated to be more appropriate for the analysis of the active compounds in A. paniculata in that it is easier and less expensive to use and does not suffer from contamination of the chromatographic column. Copyright © 2002 John Wiley & Sons, Ltd.
High‐Performance Capillary Electrophoresis Analysis of mate infusions prepared from stems and leaves of Ilex paraguariensis using Automated Micellar Electrokinetic Capillary Chromatography
Authors: Pomilio Alicia B. , Trajtemberg Silvia , Vitale Arturo A. 
Published: September 2002

AbstractAn automated micellar electrokinetic capillary chromatographic method has been developed in order to determine xanthines, e.g. caffeine, theobromine and theophylline, and chlorogenic acid in samples of yerba mate (Ilex paraguariensis). The target constituents were detected by photodiode array, and quantified by an external standard method. In addition, each constituent was collected separately and identified by EIMS. The method has been used to analyse 30 samples of mate infusions prepared at 30 and 75°C with milled leaves and stems of 14 commercial brands which had been subjected to different elaboration processes. Suspended powdered material of each infusion was also analysed after three sieving steps. There was a remarkable difference in the relative xanthine composition of the finely suspended material, the amount of which varied according to the yerba mate brand, the elaboration process and the temperature of the infusion. The importance of these results with respect to gastrointestinal disorders which have been observed by habitual consumers of mate are discussed. Copyright © 2002 John Wiley & Sons, Ltd.
A comparison of different lysis buffers to assess allele dropout from single cells for preimplantation genetic diagnosis
Authors: Thornhill Alan R. , McGrath John A. , Eady Robin A. J. , Braude Peter R. , Handyside Alan H. 
Published: September 2002

AbstractSingle cell polymerase chain reaction (PCR) for preimplantation genetic diagnosis (PGD) requires high efficiency and accuracy. Allele dropout (ADO), the random amplification failure of one of the two parental alleles, remains the most significant problem in PCR‐based PGD testing since it can result in serious misdiagnosis for compound heterozygous or autosomal dominant conditions. A number of different strategies (including the use of lysis buffers to break down the cell and make the DNA accessible) have been employed to combat ADO with varying degrees of success, yet there is still no consensus among PGD centres over which lysis buffer should be used (ESHRE PGD Consortium, 1999). To address this issue, PCR amplification of three genes (CFTR, LAMA3 and PKP1) at different chromosomal loci was investigated. Single lymphocytes from individuals heterozygous for mutations within each of the three genes were collected and lysed in either alkaline lysis buffer (ALB) or proteinase K/SDS lysis buffer (PK). PCR amplification efficiencies were comparable between alkaline lysis and proteinase K lysis for PCR products spanning each of the three mutated loci (ΔF508 in CFTR 90% vs 88%; R650X in LAMA3 82% vs 78%; and Y71X in PKP1 91% vs 87%). While there was no appreciable difference between ADO rates between the two lysis buffers for the LAMA3 PCR product (25% vs 26%), there were significant differences in ADO rates between ALB and PK for the CFTR PCR product (0% vs 23%) and the PKP1 PCR product (8% vs 56%). Based on these results, we are currently using ALB in preference to PK/SDS buffer for the lysis of cells in clinical PGD. Copyright © 2001 John Wiley & Sons, Ltd.
Congenital nephrotic syndrome presenting with increased nuchal translucency in the first trimester
Authors: Souka A. P. , Skentou H. , Geerts L. , Bower S. , Nicolaides K. H. 
Published: September 2002

AbstractCongenital nephrotic syndrome of the Finnish type (CNF) and diffuse mesangial sclerosis (DMS) are rare causes of renal failure in infants. We report two cases, one of each condition, presenting with increased nuchal translucency at the 11–14‐week scan, and review the literature. Copyright © 2002 John Wiley & Sons, Ltd.
Maternal serum activin A and inhibin A in trisomy 18 pregnancies at 10–14 weeks
Authors: Spencer Kevin , Liao Adolfo W. , Ong Charas Y. T. , Flack Nicola J. , Nicolaides Kypros H. 
Published: September 2002

AbstractIn 45 cases of trisomy 18 and 493 control pregnancies at 10–14 weeks of gestation, maternal serum inhibin A, total activin A, free β‐hCG and PAPP‐A were measured. In the trisomy 18 pregnancies the median values were 0.74 MoM for inhibin A, 1.23 MoM for activin A, 0.38 MoM for free β‐hCG and 0.16 MoM for PAPP‐A. The degree of deviation from normal in the levels of inhibin and activin is small in comparison with free β‐hCG and PAPP‐A and they are therefore unlikely to be of value in improving the sensitivity of 90% for a 1% false‐positive rate achieved by screening with fetal nuchal translucency and maternal serum free β‐hCG and PAPP‐A. Copyright © 2001 John Wiley & Sons, Ltd.
Prenatal diagnosis of 45,X and 45,X mosaicism: the need for thorough cytogenetic and clinical evaluations
Authors: Huang Bing , Thangavelu Maya , Bhatt Sucheta , J. Sandlin Constance , Wang Shengbiao 
Published: September 2002

AbstractObjectivesMosaicism involving a 45,X cell line is relatively common in prenatal diagnosis. In prenatally diagnosed cases, the prognosis of non‐mosaic 45,X and 45,X/46,XY mosaicism are different. Therefore, accurate identification of a cell line containing Y chromosome is critical for genetic counseling and postnatal management.MethodsWe investigated the ultrasound findings and outcomes of pregnancies with a 45,X cell line identified during mid‐trimester cytogenetic analysis.ResultsA total of 105 cases were found to have a 45,X cell line by standard cytogenetic analysis. Seventy‐four cases were found to have non‐mosaic 45,X at initial diagnosis. Of these 74 cases, 68 had abnormal ultrasound findings that were characteristic of Turner syndrome. Of the six cases with normal ultrasound findings, ultrasound examination was normal with male genitalia identified in three cases. Thorough cytogenetic and fluorescent in situ hybridization (FISH) analysis identified Y chromosome material in all three cases, one with a dicentric Y;14 chromosome and the other two cases with a marker chromosome containing Sex‒determining Region (SRY) material in a small portion of the cells. In contrast, in 31 cases with a mosaic 45,X karyotype, ultrasound abnormality was identified only in one case.ConclusionsThe present data suggest the need for follow‐up ultrasound examination and thorough cytogenetic and molecular analysis for Y chromosome material in 45,X cases with normal ultrasound findings. Copyright © 2002 John Wiley & Sons, Ltd.
Thermocoagulation of fetal sacrococcygeal teratoma
Authors: Hang Lam Yung , Hoi Yin Tang Mary , Wai Hung Shek Tony 
Published: September 2002

AbstractFetal sacrococcygeal teratoma can lead to a high output cardiac failure resulting in hydrops fetalis. One of the prenatal therapeutic options is to occlude the feeding vessels by radiofrequency ablation. We present a case of fetal sacrococcygeal teratoma diagnosed at 13 weeks of gestation. The tumour increased in size more than 100‐fold over 5 weeks causing polyhydramnios and cardiac and placental enlargement. Thermocoagulation was performed at 18 weeks' gestation by passing an insulated electric wire through an 18‐gauge needle placed close to the feeding vessels of the tumour at its neck. Blood supply to the tumour was successfully reduced. However, fetal death was diagnosed 2 days after the procedure. We speculate that it may be safer to limit the extent of coagulation in one attempt but to repeat the procedure at a later stage when necessary. Copyright © 2002 John Wiley & Sons, Ltd.
The development of the fetal thymus: an in utero sonographic evaluation
Authors: Zalel Yaron , Gamzu Ronni , Mashiach Shlomo , Achiron Reuven 
Published: September 2002

AbstractObjectivesTo establish a nomogram for fetal thymus size during gestation.MethodsThe study is a prospective, cross‐sectional evaluation of 403 male and female fetuses between 14 and 38 weeks of normal singleton pregnancies. Measurements of fetal thymus size were performed by high‐resolution transvaginal ultrasonography between 14 and 17 weeks' gestation, and by transabdominal ultrasonography after 18 weeks' gestation.ResultsAdequate thymus size measurements were obtained in all 403 fetuses. Thymus size as a function of gestational age was expressed by the regression equation: (square root) thymus size (mm)=–39.39+4.41×gestational age (weeks). The correlation coefficient, r=0.965, was found to be highly statistically significant (p<0.0001). The normal mean and the 90% prediction limits were defined.ConclusionThe present data offer the normal range of fetal thymus size from early stages of gestation that may allow intrauterine assessment of its development. It may be helpful in the prenatal diagnosis of thymic pathologies. Copyright © 2002 John Wiley & Sons, Ltd.
A second case of intrauterine growth retardation and primary hypospadias associated with a trisomy 22 placenta but with biparental inheritance of chromosome 22 in the fetus
Authors: Bryan Jennifer , Peters Michelle , Pritchard Gary , Healey Sue , Payton Diane 
Published: September 2002

AbstractWe report a case of severe intrauterine growth retardation (IUGR) and hypospadias in association with trisomy 22 diagnosed following chorionic villus sampling (CVS). Subsequent analysis of amniotic fluid cultures showed a normal male karyotype, 46,XY. As a previous case had been reported with similar abnormalities, in association with maternal uniparental disomy (UPD) 22, molecular studies were also performed. Microsatellite marker studies showed biparental inheritance. Follow‐up studies after delivery showed a normal cell line in lymphocytes with the trisomy appearing to be confined to the placenta. The present case concurs with other earlier reports that maternal UPD for chromosome 22 has no impact on the phenotype. The features seen in the fetus are most likely the result of placental dysfunction due to trisomy, tissue‐specific mosaicism and/or the effects of local growth restriction. Copyright © 2002 John Wiley & Sons, Ltd.
Testing normality of fetal DNA concentration in maternal plasma at 10–12 completed weeks' gestation: a preliminary approach to a new marker for genetic screening
Authors: Farina Antonio , Caramelli Elisabetta , Concu Manuela , Sekizawa Akihiko , Ruggeri Roberto , Bovicelli Luciano , Rizzo Nicola , Carinci Paolo 
Published: September 2002

AbstractObjectivesTo test the distribution of fetal DNA in maternal plasma expressed as gen/eq in a population of normal pregnancies.MethodsPeripheral blood samples were obtained from 63 women (85% ⩾35 years of age at delivery) bearing a euploid male fetus. Each patient underwent chorionic villus sampling (CVS) for karyotype analysis and/or β‐ thalassemia screening. Ultrasound scanning was used to determine gestational age. At 10–12 weeks' gestation, a peripheral blood sample was collected followed by CVS. To detect the Y chromosome‐specific sequences (SRY) quantitative polymerase chain reaction (PCR) analysis was used. Normal distribution of the data was tested by means of the Kolmogorov‐Smirnov (KS) test. A Symmetry test (reliability p>0.05) was used to evaluate the reliability of the median.ResultsOnly after natural logarithmic transformation did the data display a normal distribution. The median value of fetal DNA was 23.3 gen/eq (range 2.08–195), interquartile range 18.57–45.4. A Pearson test showed a significant correlation between gestational age and fetal DNA concentration (r=0.25, p=0.045).ConclusionThe present finding is a preliminary step towards a possible integration of fetal DNA with other variables (biochemical and/or ultrasound). It may serve to improve the discrimination of the screening for genetic diseases in the first trimester. Because of the relatively high dispersion, adjustments for possible covariates would appear to be necessary in further studies. Copyright © 2002 John Wiley & Sons, Ltd.