bluuebunny/crossref_metadata_2025 huggingface dataset:
Antibody microarrays: An evaluation of production parameters
Authors: Kusnezow Wlad , Jacob Anette , Walijew Alexandra , Diehl Frank , Hoheisel Jörg D.
Published: March 2003

Antibody microarrays could have an enormous impact on the functional analysis of cellular activity and regulation, especially at the level of protein expression and protein‐protein interaction, and might become an invaluable tool in disease diagnostics. The array surface is bound to have a tremendous influence on the findings from such studies. Apart from the basic issue of how to attach antibodies optimally without affecting their function, it is also important that the cognate antigens, applied within a complex protein mixture, all bind to the arrayed antibodies irrespective of their enormous variety in structure. In this study, various factors in the production of antibody microarrays on glass support were analysed: the modification of the glass surface; kind and length of cross‐linkers; composition and pH of the spotting buffer; blocking reagents; antibody concentration and storage procedures, in order to evaluate their effect on array performance. Altogether, data from more than 700 individual array experiments were taken into account. In addition to home‐made slides, commercially available systems were also included in the analysis.
Short communication The rapid detection of low molecular mass proteins differentially expressed under biological stress for four Helicobacter spp. using ProteinChip® technology
Authors: Hynes Sean O. , McGuire Jim , Falt Tobias , Wadström Torkel
Published: March 2003

Helicobacter pylori is one of the most prevalent human pathogens in the world and is the aetiological agent of gastritis, peptic ulcer disease and gastric malignancies. In addition H. pylori and other novel members of the genus are capable of successfully colonising the bile‐rich niche of the upper intestine and are associated with a diverse range of intestinal pathologies. Surface‐enhanced laser desorption/ionisation‐time of flight mass spectrometry was used to analyse surface extracts from H. pylori, Helicobacter bilis, Helicobacter pullorum and “Helicobacter sp. flexispira” to characterise cell surface changes following bile stress. The system detected two distinct response patterns to bile stress on the cell surface of Helicobacter spp. in vitro. The first involved the increase under bile stress of peaks at 7.6 and 7.9 kDa for H. billis and H. pullorum, respectively. In contrast both “Helicobacter sp. flexispira” and a clinical isolate of H. pylori had similar response profiles to bile stress. Both strains had at least three low mass peaks decreased under bile stress and a single peak induced by bile stress. The present study has established the use of ProteinChip® technology to analyse helicobacter‐related proteomics. Specifically this study has established that different patterns are generated in response to bile stress among various pathogenic Helicobacter spp. which may give insights into the ability of these strains to colonise different niches.
Depletion of the highly abundant protein albumin from human plasma using the Gradiflow
Authors: Rothemund Deborah L. , Locke Vicki L. , Liew Audrey , Thomas Theresa M. , Wasinger Valerie , Rylatt Dennis B.
Published: March 2003

Analysis of complex protein samples by two‐dimensional electrophoresis (2‐DE) is often more difficult in the presence of a few predominant proteins. In plasma, proteins such as albumin mask proteins of lower abundance, as well as significantly limiting the amount of protein that can be loaded onto the immobilized pH gradient strip. In this paper the Gradiflow, a preparative electrophoresis system, has been used to deplete human plasma of the highly abundant protein albumin under native and denatured conditions. A three step protocol incorporating a charge separation to collect proteins with an isoelectric point greater than albumin and two size separations to isolate proteins larger and smaller than albumin, was used. When the albumin depleted fractions were analysed on pH 3–10 2‐DE gels, proteins that were masked by albumin were revealed and proteins not seen in the unfractionated plasma sample were visualised. Matrix‐assisted laser desorption/ionisation‐time of flight mass spectrometry analysis confirmed the identification of the protein that lies beneath albumin to be C4B‐binding protein α chain. The liquid fractions from the Gradiflow separations were also analysed by liquid chromatography‐tandem mass spectrometry to confirm the proteins were separated according to their size and charge mobility in an electric field.
Proteomic profiling of proteins associated with urokinase plasminogen activator receptor in a colon cancer cell line using an antisense approach
Authors: Ahmed Nuzhat , Oliva Karen , Wang Yao , Quinn Michael , Rice Greg
Published: March 2003

Expression of urokinase plasminogen activator (uPA) and its receptor (uPAR) strongly correlates with a malignant tumour cell phenotype. In the multistep process of metastasis, uPA binding to uPAR influences different cellular functions. In the present study, a highly metastatic colon cancer cell line, HCT116 was transfected with an expression vector containing a 5’ uPAR cDNA fragment in an antisense orientation. This construct was most effective in reducing uPAR cell surface expression as confirmed by flow cytometry analysis. Antisense transfection of HCT116 cells had no effect on proliferation but the following effects were observed: (1) a 1.3‐fold decreased adhesion; (2) a two‐fold decreased Erk MAP kinase activity; (3) a 2.7‐fold decrease in Src kinase activity; (4) a 1.5‐ and two‐fold decrease in uPA cell surface expression and secretion; (5) abrogation of promatrix metalloproteinase‐9 secretion; and (6) a complete suppression of plasminogen‐dependent matrix degradation. Using proteomic analysis, we demonstrate loss of approximately 200 proteins and quantitative differences in the expression of 141 other proteins in an antisense‐clone compared to wild‐type and mock‐transfected control. Such changes in protein expression with the down‐regulation of uPAR may be an important contributor in colon cancer progression and metastasis and may not only provide a basis to develop a proteomic data bank of uPAR‐mediated signaling molecules but may also lead to the development of therapeutic approaches for the cure and better management of colon cancer.
The role of peptide deformylase in protein biosynthesis: A proteomic study
Authors: Bandow Julia Elisabeth , Becher Dörte , Büttner Knut , Hochgräfe Falko , Freiberg Christoph , Brötz Heike , Hecker Michael
Published: March 2003

Recently we investigated the influence of classical and emerging antibiotics on the proteome of Bacillus subtilis including in our studies actinonin, a potent novel inhibitor of peptide deformylase. The protein synthesis pattern under actinonin treatment changed so dramatically that a direct comparison to the control pattern was impossible. Dual channel imaging revealed that actinonin treatment caused the majority of newly synthesised proteins to accumulate in spots different from the ones usually observed, indicating a more acidic isoelectric point. Two strategies were used to investigate the nature of the charge shift. In the first place, protein patterns of a conditional peptide deformylase mutant under nonrepressing and repressing conditions were compared. Secondly, several protein pairs excised from two‐dimensional (2‐D) gels of the peptide deformylase mutant, exponentially growing untreated wild‐type and the actinonin treated wild‐type were investigated with matrix‐assisted laser desorption/ionization and electrospray ionization (ESI) time of flight mass spectrometry (TOF MS) for the existence of N‐terminal formylation. Under nonrepressing conditions the mutant protein pattern resembled that of the wild‐type. The loss of peptide deformylase activity under repressing conditions led to the same pI shift observed for actinonin treatment in the wild‐type. Quadrupole TOF‐MS on 11 protein pairs proved that the remaining N‐terminal formyl residue was indeed responsible for the charge shift. Eight of these protein pairs were also present on 2‐D gels of exponentially growing B. subtilis, where the more acidic, still formylated protein species represented the smaller parts.
Mimicry of dimerization by synthetic peptides designed to target homologous regions of proteins
Authors: Dwyer Donard S. , Ardizzone Timothy D.
Published: March 2003

Rapid progress in sequencing various genomes has highlighted the need for the development of biochemical reagents for the detection of thousands of expressed gene products. The magnitude of this detection problem exceeds current technical capabilities. In an attempt to address this shortcoming, a novel approach has been developed called mimicry of dimerization. Peptide tags have been designed to bind to a specific region of parvalbumin on the basis of amino acid sequence homology with this segment. Multivalent ligands were produced by coupling the synthetic peptides to activated dextran polymers and binding was assessed by chemiluminescence of enhanced avidity reactions using a high density of target protein at the binding surface. Binding of the peptide ligands to parvalbumin was strongest under assay conditions that enriched for native monomeric protein and was affected by pH, temperature and solvent conditions. The results suggest that it should be possible to develop specific reagents for tagging proteins on the basis of sequence and secondary structure information.
Drug induced proteome changes in Candida albicans: Comparison of the effect of β(1,3) glucan synthase inhibitors and two triazoles, fluconazole and itraconazole
Authors: Bruneau Jean‐Michel , Maillet Isabelle , Tagat Eric , Legrand Raymond , Supatto Françoise , Fudali Claude , Caer Jean‐Pierre Le , Labas Valérie , Lecaque Dominique , Hodgson John
Published: March 2003

The dimorphic fungus Candida albicans is an opportunistic human pathogen. Candidiasis is usually treated with azole antifungal agents. However clinical treatments may fail due to the appearance of resistance to this class of antifungal agents in Candida. Echinocandin derivatives are an alternative for the treatment of these fungal infections and are active against azole resistant isolates of C. albicans. Azoles inhibit the lanosterol 14 α demethylase which is a key enzyme in the synthesis of ergosterol. In contrast, the echinocandin class of antibiotics inhibit noncompetitively β‐(1,3)‐D‐glucan synthesis in vitro. We have investigated the impact of mulundocandin on the proteome of C. albicans and compared it to those of a mulundocandin derivative, as well as to two azoles of different structure, fluconazole and itraconazole. The changes in gene expression underlying the antifungal responses were analyzed by comparative 2‐D PAGE. Dose dependant responses were kinetically studied on C. albicans grown at 25°C (yeast form) in synthetic dextrose medium. This study shows that antifungals with a common mechanism of action lead to comparable effects at the proteome level and that a proteomics approach can be used to distinguish different antifungals, with the promise to become a useful tool to study drugs of unknown mechanism of action.
Functionalizing the interior of dendrimers: Synthetic challenges and applications
Authors: Hecht Stefan
Published: March 2003

Chemists' fascination with dendrimers mainly originates from their unique architecture and its exploitation for the design of well‐defined functional macromolecules. Depending on the nature of the synthesis, functionalization is traditionally introduced at the core, the periphery, or both. However, the specific incorporation of functional groups at the interior layers, i.e., generations, represents a considerable synthetic hurdle that must be overcome for the full potential of dendrimers to be realized. This review covers recent advances in this emerging frontier of dendrimer science with a particular focus on covalent modifications. Monomer design, syntheses, and properties of various dendritic backbone types are discussed. Internal functionalization dramatically increases the degree of complexity that can be implemented into a dendrimer macromolecule and, therefore, promises to lead to smart materials for future applications in bio‐ and nanotechnologies. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1047–1058, 2003
Poly(ester anhydride)s prepared by the insertion of ricinoleic acid into poly(sebacic acid)
Authors: Krasko Michal Y. , Shikanov Ariella , Ezra Aviva , Domb Abraham J.
Published: March 2003

New degradable poly(ester anhydride)s were prepared by the melt polycondensation of diacid oligomers of poly(sebacic acid) (PSA) transesterified with ricinoleic acid. The transesterification of PSA with ricinoleic acid to form oligomers was conducted via a melt bulk reaction between a high molecular weight PSA and ricinoleic acid. A systematic study on the synthesis, characterization, degradation in vitro, drug release, and stability of these polymers was performed. Polymers with weight‐average molecular weights of 2000–60,000 and melting temperatures of 24–77 °C were obtained for PSA containing 20–90% (w/w) ricinoleic acid. NMR and IR analyses indicated the formation of ester bonds along the polyanhydride backbone. These new degradable copolymers have potential use as drug carriers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1059–1069, 2003
Synthesis of branched polypropylene with isotactic backbone and atactic side chains by binary iron and zirconium single‐site catalysts
Authors: Ye Zhibin , Zhu Shiping
Published: March 2003

This article reports the use of a binary single‐site catalyst system for synthesizing comb‐branched polypropylene samples having isotactic polypropylene (iPP) backbones and atactic polypropylene (aPP) side chains from propylene feedstock. This catalyst system consisted of the bisiminepyridine iron catalyst {[2‐ArNC(Me)]2C5H3N}FeCl2 [Ar = 2,6‐C6H3(Me)2] (1) and the zirconocene catalyst rac‐Me2Si(2‐MeBenz[e]Ind)2ZrCl2 (2). The former in situ generated 1‐propenyl‐ended aPP macromonomer, whereas the latter incorporated the macromonomer into the copolymer. The effects of reaction conditions, such as the catalyst addition procedure and the ratio of 1/2 on the branching frequency, were examined. Copolymer samples having a branching density up to 8.6 aPP side chains per 1000 iPP monomer units were obtained. The branched copolymers were characterized by 13C NMR and differential scanning calorimetry. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1152–1159, 2003
Novel approach to the chemical modification of poly(vinyl alcohol): Phosphorylation
Authors: Liu Ying‐Ling , Chiu Yie‐Chan
Published: March 2003

The chemical modification of poly(vinyl alcohol) (PVA) was performed through oxidation followed by nucleophilic addition. PVA was oxidized by KMnO4 to form vinyl ketone units along the polymer backbone. The chemical modification of PVA was then conducted through the reaction of the carbonyl group of the vinyl ketone unit with 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) as a nucleophile. Through this approach, the phosphorous DOPO group was attached onto the carbon atom of the polymer main chain rather than onto the pendent hydroxyl groups of PVA. The formed DOPO‐containing PVA showed improved thermal stability, organosolubility, and flame retardance. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1107–1113, 2003
Effect of shear flow on the phase‐separation behavior in a blend of polystyrene and polyvinyl methyl ether
Authors: Lei Caihong , Li Guangxian , Yang Qi , Chen Dahua , Jiang Sujun
Published: March 2003

The phase behavior and phase‐separation dynamics of polystyrene/polyvinyl methyl ether (PS/PVME) blend with a critical composition of 70 vol % PVME were examined with a light scattering technique under a shear‐rate range of 0.1–40 s−1. If the shear rates were less than 8 s−1 and the starting temperatures of the measurement were 343 and 383 K, respectively, two cloud points were observed, whereas after the shear rate was higher than 8 s−1, only one cloud point existed, 20 K higher than that of the static state of the blend. Investigation of the phase‐separation dynamics at 443 K suggested that in the vorticity direction the phase‐separation behavior at the early stage and the later stage can be explained by Cahn–Hilliard linearized theory and the exponent growth law, respectively. Phase separation occurs after a shearing time, which was called a delay time τd. The delayed time τd, the apparent diffusion coefficient, and the exponent term of the blend show strong dependence on shear rates. A theoretical prediction of the phase behavior of PS/PVME under a shear flow field by introducing an elastic energy term into Flory's equation‐of‐state theory was made, and the prediction was consistent with the experimental results. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 661–669, 2003
Tensile creep of thermoplastics: Time‐strain superposition of non‐iso free‐volume data
Authors: Kolařík Jan
Published: March 2003

The dimensional stability of thermoplastics is characterized by their tensile compliance D(t,σ,T) as a function of time t, stress σ, and temperature T. Creep retardation times are controlled by the free volume available for underlying molecular (segmental) motions. Tensile deformation of polymeric materials, whose Poisson ratio is smaller than 0.5, is accompanied by volume dilatation that can be identified with an increase in available free volume. Consequently, a steady increase in strain with time during tensile creep experiments accounts for shortening of the retardation times. The superposition of as‐received tensile compliance curves is difficult because any point of a curve requires a shift factor along the time axis that differs from those of other points. In this article, tensile creep at a constant stress and temperature is viewed as a non‐iso free‐volume process. A procedure is proposed to transform as‐received data to a pseudo‐iso free‐volume state that eliminates this deficiency and permits construction of a generalized compliance curve for the pseudo‐iso free‐volume state. This curve can be used for calculation of real‐time‐dependent compliance for any selected stress in the range of reversible deformations. As the superposed curve can be generated with several short‐term creep tests (e.g., 100 min) for a series of stresses, the proposed procedure saves experimental time. The effects of physical aging on tensile compliance (observed previously by other researchers) are interpreted in terms of the proposed approach in appendix A. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 736–748, 2003
Effect of the repeated unit length of guest polymers on the molecular motion of polymer blends within a miscible window
Authors: Hung Albert Y. C.
Published: March 2003

The effect of the repeated unit length on the substantially increasing molecular motion and entropy change (−TΔSm) of polymer blends was investigated with solid‐state 13C NMR and differential scanning calorimetry within a miscible window. The hydrogen‐bonding strength, from the formation of the phenolic–polyester interaction, was not high enough to overcome the breaking‐off of the self‐association of the phenolic. With respect to the increasing repeated unit length, the polyester resonance intensity of the solid‐state 13C NMR spectra was weakened because of the reduction in the cross‐polarization efficiency in highly mobile samples. The glass‐transition temperature of the blend and the proton spin–lattice relaxation time from NMR experiments were also reduced. The effect of the reduced hydrogen‐bonding strength on blending brought about a tendency of higher entropy (−TΔSm) and higher molecular mobility of the blend. Accordingly, poly(decamethylene adipate) possessed the longest repeated unit length and exhibited the most mobile one in this phenolic/polyester blend family. The molecular segmental motion and entropy progressively increased while the repeated unit length of the guest polymers increased within a miscible window. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 679–686, 2003
Domain size equilibration in sphere‐forming block copolymers
Authors: Cavicchi Kevin A. , Lodge Timothy P.
Published: March 2003

The kinetics of domain size equilibration were studied for asymmetric poly(ethylene‐alt‐propylene)‐b‐poly(dimethyl siloxane) (EPDMS) and polyisoprene‐b‐poly(dimethyl siloxane) (IDMS) block copolymers in the body‐centered cubic ordered phase. Small‐angle X‐ray scattering measurements of the principal peak position (q*) were made as a function of time after temperature jumps within the ordered state. The equilibration times were remarkably long, especially on cooling and for temperatures below 100 °C. For example, after a quench to 40 °C, q* for EPDMS had not fully equilibrated even after several weeks of annealing; IDMS required several days to equilibrate at the same temperature. In contrast, a lamella‐forming EPDMS sample was able to adjust q* within the timescale of the measurements (i.e., minutes) with both heating and cooling over the same temperature range. Measurements of tracer diffusion indicated that chain mobility was not the rate‐limiting step, although differences in mobility did account for the differences between EPDMS and IDMS. Rather, the limiting step was the required reduction in the number density of spheres on cooling; the disappearance of spheres, either by evaporation or by fusion, provided a large kinetic barrier. Lamellae, however, could adjust domain dimensions simply by local displacements of individual chains. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 715–724, 2003
Synthesis and orientation study of a magnetically aligned liquid‐crystalline chitin/poly(acrylic acid) composite
Authors: Nge Thi Thi , Hori Naruhito , Takemura Akio , Ono Hirokuni , Kimura Tsunehisa
Published: March 2003

A high magnetic field of 5 T was used to fabricate a magnetically aligned, optically anisotropic, liquid‐crystalline chitin/poly(acrylic acid) composite. The aligned mesophase was fixed by photoinitiated free‐radical polymerization. From an examination of polarized optical micrographs and an X‐ray diffraction study, a high degree of orientation of 0.70 was observed for the composite with a higher liquid‐crystalline chitin concentration (10.70 wt %); the orientation was reduced with a decreased chitin concentration at a given acrylic acid concentration. The X‐ray data for the developed composite showed a uniplanar orientation for the chitin crystallites, with its molecular long axes perpendicular to the direction of the magnetic field. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 711–714, 2003
The evolving experience of illness for Chinese women with breast cancer: A qualitative study
Authors: Lam Wendy W.T. , Fielding Richard
Published: March 2003

The study of illness meaning in cancer in western communities has usually focused on causal attributions. We report a phenomenological study of 17 Hong Kong Chinese women with breast cancer, interviewed on completion of initial treatment, and describe how the illness experience and hence, meaning evolves for women in the Hong Kong Chinese culture. Themes arising from the identification and treatment of the disease include the difficulty of living in uncertainty and of maintaining and regaining normalcy in a superstitious society. The initial uncertainty of disease detection and the diagnostic process are characterized by shock and disbelief mingled with fear of death. Treatment choice presents women with difficulties arising from more uncertainty over the pressure to make quick decisions and the dilemma of death or mutilation. Following treatment, re‐evaluation, re‐prioritizing and positive life‐re‐evaluation occur. Changes in appearance proved problematic for those women who tried to hide their disease to protect themselves against stigmatization and social exclusion. In many ways, these findings parallel studies on western populations, suggesting that a common disease–medical care process is a predominant influence in shaping breast cancer experience. Implications for care are drawn from these data. Copyright © 2002 John Wiley & Sons, Ltd.
Living with the worry of cancer: health perceptions and behaviors of elderly people with self, vicarious, or no history of cancer
Authors: Benyamini Yael , McClain Colleen S. , Leventhal Elaine A. , Leventhal Howard
Published: March 2003

Cancer is a major health threat that has a long‐term impact on quality of life and health worries. The present study is focused on two major issues: (1) the impact that a history of cancer has on reactions to other diseases, in addition to cancer and general health worries; and, (2) the impact that having lived with someone who had cancer has on health perceptions and behaviors. All 108 participants had osteoarthritis, a symptomatic but benign disease (49 people have had cancer, 22 had lived with a cancer patient, and 37 had not had any close experience with cancer). Cancer and health worries were lowest among the people with vicarious experience, while monitoring for bodily signs was similar and highest in both cancer experience groups. Reactions to arthritis suggest more vigilance among people who have had self or vicarious experience with cancer, while reactions to ambiguous symptoms suggest vigilance especially among those with a personal history of cancer. Overall, the findings suggest that the effects of self‐experience with cancer and of close experience with a cancer patient may be long‐term and impact upon both health perceptions and behaviors. Copyright © 2002 John Wiley & Sons, Ltd.
Pediatric pulmonary carcinoid: A case report and review of the literature
Authors: Moraes Theo J. , Langer Jacob C. , Forte Vito , Shayan Katayoon , Sweezey Neil
Published: March 2003

We report on the youngest known patient with a pulmonary carcinoid, a rare tumor in children. We review the management of and prognosis for this tumor. Diagnosis can be delayed because of low clinical suspicion and the many ways in which these tumors can present. Treatment is surgical and geared towards complete resection while sparing healthy lung parenchyma. Prognosis is generally good, but careful long‐term follow‐up is needed for potential recurrences or associated tumors. Pediatr Pulmonol. 2003; 35:318–322. © 2003 Wiley‐Liss, Inc.
Oxygen and ventilator weaning during inpatient pediatric pulmonary rehabilitation
Authors: Kharasch Virginia S. , Haley Stephen M. , Dumas Helene M. , Ludlow Larry H. , O'Brien Jane E.
Published: March 2003

Rates of oxygen and ventilator weaning, and factors related to successful weaning in inpatient pediatric pulmonary programs for infants and young children, have not been frequently reported in the literature. A retrospective review was conducted of 34 infants and toddlers with either a diagnostic condition of prematurity (PM) or congenital anomalies/neuromuscular disease (CA/NM) discharged from an inpatient pulmonary program. These cases represent 67 hospital admission‐discharge episodes over a 6‐year period. The rate of successful oxygen weaning (decrease to 0 hr per day) and ventilator weaning (decrease to <12 hr per day) and predictive factors related to successful ventilator weaning per admission‐discharge episode were examined. Successful oxygen weaning was achieved during 24% and successful ventilator weaning was achieved during 30% of the admission‐discharge episodes. No significant relationships were found between the selected demographic and clinical factors and oxygen weaning. Using a logistic regression model, the major variable associated with successful ventilator weaning per admission‐discharge episode was diagnostic condition. Age at admission and the presence of comorbidities added slightly to the prediction model. The overall model yielded 86% accuracy for predicting a decrease in ventilator hours. However, projecting in which episodes children will not be weaned (negative predictive value = 88.9%) was more accurate than projecting in which episodes children will be weaned (positive predictive value = 73.3%). Although the program achieved a relatively low rate of successful ventilator weaning, children with a diagnostic condition of prematurity were more likely to be successfully weaned during inpatient pulmonary rehabilitation. Pediatr Pulmonol. 2003; 35:280–287. © 2003 Wiley‐Liss, Inc.
Clinical characteristics of children with tracheobronchial anomalies
Authors: Sánchez Ignacio , Navarro Héctor , Méndez Mireya , Holmgren Nils , Caussade Solange
Published: March 2003

Tracheobronchial anomalies (TBA) originate between the third and sixteenth week of gestation, and they primarily affect the main bronchi. The reported incidence varies between 1–3% of pediatric endoscopic studies. The objective of our review was to describe the clinical characteristics of patients with TBA diagnosed by flexible bronchoscopy (FB). During the period from March 1993–May 2001, we performed 580 FB at the Pediatric Services of the Catholic University Hospital. During this study period, 52 patients (9.65%) had a TBA (32 males, or 61.5%), with a mean age of 21.2 months (range, 7 days to 6 years). In 39 cases (75%), the diagnosis was made under age 2 years. Thirty‐six patients with symptoms related to TBA were symptomatic (70%), and in 16 cases (30%) the TBA was an accidental finding during FB. The main clinical manifestations were recurrent atelectasis of the right upper lobe (RUL), recurrent pneumonia, or congenital stridor. Most of the TBA were localized at the RUL bronchus (47%) and were characterized by an anomaly at its origin, either agenesis or a supernumerary bronchus. Also, we found patients with tracheal bronchus and congenital tracheal stenosis. In 6 patients (12%), we had more than one TBA, the most frequent being the association between RUL and RML anomalies. In 12 cases we found another congenital airway anomaly, mainly laryngomalacia. Patients had associated diseases, such as genetic disorders in 16 cases (particularly Down syndrome), and congenital cardiopathies. In summary, in our clinical experience, TBA are more frequent than previously reported. The majority of young patients have symptoms or signs, and most are localized to the RUL. We found patients with more than one TBA, laryngomalacia associated with TBA, and at a high frequency related to Down syndrome. Pediatr Pulmonol. 2003; 35:288–291. © 2003 Wiley‐Liss, Inc.
Repeated blood gas monitoring in healthy children and adolescents by the transcutaneous route
Authors: Lagerkvist Anna‐Lena , Sten Gunilla , Redfors Staffan , Holmgren Daniel
Published: March 2003

The aim of the study was to establish transcutaneous oxygen tension (tcPO2), carbon dioxide tension (tcPCO2), and oxygen saturation (tcSO2) values and to investigate the intra‐ and interindividual variation in these values in healthy children and adolescents. Forty‐one healthy children/adolescents (21 girls; mean age, 12.1 years; SD, 3.5; range, 5.0–19.0 years) participated. Continuous recordings of tcPO2, tcPCO2, tcSO2, and heart rate (HR) were made for 30 min on two occasions, with a mean interval of 10.3 days, with the child/adolescent in a sitting position. The respiratory rate (RR) was counted manually during the last 5 min of each recording. The mean values of tcPO2, tcPCO2, tcSO2, HR, and RR during the last 5 min of the recordings were reported. At the first recording, the mean value for tcPO2 was 10.8 kPa (SD 1.0), for tcPCO2 5.1 kPa (0.4), for tcSO2 97.4% (1.1), for HR 82.2 min−1 (9.9), and for RR 19.0 min−1 (2.8). The coefficient of variation for tcPO2 was 9.3%, for tcPCO2 7.8%, for tcSO2 1.1%, for HR 12.0%, and for RR 14.7%. The mean intraindividual variation in tcPO2 was 0.3 kPa (SD 1.0), tcPCO2 0.0 kPa (0.5), tcSO2 0.1% (1.3), HR 0.1 min−1 (7.7), and RR 0.5 min−1 (2.7). No significant differences were observed in tcPO2, tcPCO2, tcSO2, HR, or RR between the two recordings. In conclusion, the reproducibility of tcPO2, tcPCO2, and tcSO2 monitoring during 30 min in healthy children and adolescents was good. This indicates that transcutaneous blood gas monitoring may be used to document significant changes in blood gas tensions and oxygen saturation over time. Pediatr Pulmonol. 2003; 35:274–279. © 2003 Wiley‐Liss, Inc.
Migration of Plasticizer between Bonded Propellant Interfaces
Authors: Gottlieb Levi , Bar Sigalit
Published: March 2003

Plasticizer migration across bonded propellant interfaces during cure has been shown to have a measurable effect on propellant properties compared to each propellant by itself. This shows that the curing period is significant to the migration phenomenon. The plasticizer migration has been shown to have a direct influence on tensile strength for short aging periods up to the point the plasticizer reaches equilibrium. The tensile data for short aging periods have been shown to follow an empirical equation connecting the physical characteristics of plasticizer migration with increasing propellant tensile strength. The diffusion coefficient has been evaluated on the basis of this relation from a plot of σ$ ^{\it m}_{\rm t}$ versus t1/2 and was in good agreement with the diffusion coefficient from the plasticizer content data.
Progress in Understanding Plasma‐Propellant Interaction
Authors: Kappen Klaus , Beyer Richard
Published: March 2003

To explore the phenomena of the plasma‐propellant interaction (PPI) and to point out the role of radiation, a series of experiments have been performed at the U.S. Army Research Laboratory. For this, the plasma radiation to the propellant has been separated from all other energy transfer mechanisms. The results clearly indicate that the observed structural damage of translucent JA2 samples is due to radiation only. An other aim of this work is to clarify some misunderstandings in analyzing plasma‐propellant interaction. By variation of the electrical pulse length it will be shown that electrical energy is in no way a useful parameter to characterize propellant response to variable plasma igniter systems.
Acceleration and Viscoplastic Deformation of Spherical and Cylindrical Casings under Explosive Loading
Authors: Tan Duowang , Sun Chengwei , Wang Yanping
Published: March 2003

A theoretical model to predict continuous deformation and acceleration of spherical or cylindrical metallic casings driven by detonation products inwards or outwards before fracture occurring is proposed in this paper. The casing materials are assumed to be rigid viscoplastic medium and the geometries are one dimension i.e., the explosive charge is initiated at the spherical center or on the cylindrical axis in the divergent case, or uniformly on the explosive shell's outer surface in the convergent case. The acceleration movements of spherical and cylindrical casings calculated with this model are in good agreement with experimental and numerical results performed with the finite element hydrocode DYNA2D. It is concluded that this model describes well one‐dimensional divergent and convergent movements of spherical or cylindrical casings under explosive loading, and provides a useful method to explore related problems, such as shell's fragmentation, its maximum velocity before fracture, blast wave in the near area adjacent to the casing and solid liner implosion.
An elementary aspect of the Weyl‐Wigner representation
Authors: Dahl J.P. , Schleich W.P.
Published: March 2003

It is an elementary aspect of the Weyl‐Wigner representation of quantum mechanics that the dynamical phase‐space function corresponding to the square of a quantum‐mechanical operator is, in general, different from the square of the function representing the operator itself. We call attention to some conceptual consequences of this fact.
Coherent states for hydrogen‐like atom in the presence of Aharonov‐Bohm effect
Authors: Drăgănescu Gh.E. , Avram N.M.
Published: March 2003

For a hydrogenlike atom introduced in an Aharonov‐Bohm potential due a infinite solenoid it was established different operators corresponding to different representations of the system. For this system we studied the the displacement coherent states and harmonic oscillatorlike coherent states. The average values of some observables in different coherent states have been done.
Quantum cloning of orthogonal qubits
Authors: Fiurášek J. , Iblisdir S. , Massar S. , Cerf N.J.
Published: March 2003

An optimal universal cloning transformation is derived that produces M copies of an unknown qubit from a pair of orthogonal qubits. For M>6, the corresponding cloning fidelity is higher than that of the optimal copying of a pair of identical qubits.
Quantum operators in Weyl quantization procedure via Wigner representation of quantum mechanics ‐ quantum phase operator as a special case
Authors: Davidović M.
Published: March 2003

Coherent states, in Wigner representation of quantum mechanics which is classical in structure with Wigner function playing the role of classical phase space probability distribution, and standard quantum mechanical expression for average values of corresponding Weyl quantum operators, general expression for matrix elements of the operator corresponding to phase of the oscillator by Weyl procedure, are obtained in the |n〉 basis. The general expression for matrix elements in the same basis of any other operator is also obtained. As the only mathematical technique necessary in the proposed procedure is a simple change of variables to polar coordinates in the corresponding integrals, this way to introduce Weyl phase operator, and some other operators in Weyl quantization, greatly simplifies necessary derivations and calculations.
Self‐dressing in classical and quantum electrodynamics
Authors: Compagno G. , Passante R. , Persico F.
Published: March 2003

A short review is presented of the theory of dressed states in nonrelativistic QED, encompassing fully and partially dressed states in atomic physics. This leads to the concept of the reconstruction of the cloud of virtual photons and of self‐dressing. Finally some recent results on the classical counterpart of self‐dressing are discussed and a comparison is made with the QED case. Attention is drawn to open problems and future lines of research are briefly outlined.
The quantum way to diagonalize hermitean matrices
Authors: Weigert S.
Published: March 2003

An entirely quantum mechanical approach to diagonalize hermitean matrices has been presented recently. The method is based on the measurement of quantum mechanical observables which provides the computational resource. In brief, quantum mechanics is able to directly address and output eigenvalues of hermitean matrices. Here, the example of (2×2) matrices is considered in detail. This simple case allows one to illustrate the conceptual features of the general method which is applicable to (N×N) hermitean matrices.
Dipole‐dipole coupling in the presence of dispersing and absorbing bodies
Authors: Welsch D.‐G. , Dung H.T. , Knöll L.
Published: March 2003

An effective Hamiltonian and equations of motion for treating both the resonant dipole‐dipole interaction between two‐level atoms and the resonant atom‐field interaction are derived, which can suitably be used for studying the influence of arbitrary dispersing and absorbing material surroundings on these interactions. It is shown that the dipole‐dipole interaction and the atom‐field interaction, respectively, are closely related to the real part and the imaginary part of the (classical) Green tensor. The theory is applied to the study of the transient behavior of two atoms that initially share a single excitation, with special emphasis on the role of the two competing processes of virtual and real photon exchange in the energy transfer between the atoms. To illustrate the powerfulness of the theory, specific results for the case of the atoms being near a dispersing and absorbing microsphere are presented. In particular, the regimes of weak and strong atom‐field coupling are addressed.
Quantum‐mechanical description of polarized and unpolarized light
Authors: Wünsche A.
Published: March 2003

The restrictions for density operators of unpolarized quasiplane and quasimonochromatic two‐mode light are determined by invariance with respect to SU(2) polarization transformations and it is shown that this leads only to the type of unpolarized light established in [6]. In this connection, it is clarified and underlined by group‐theoretical considerations that the “type II of unpolarized light'' derived in [8‐11] is in reality a type of polarized light with second‐order polarization (or hidden polarization in first order) and that it is obtained by invariance with respect to an axial subgroup C∞v of SU(2) or of U(2).
Photoluminescence studies of isotopically enriched silicon
Authors: Karaiskaj D. , Thewalt M.L.W. , Ruf T. , Cardona M.
Published: March 2003

In this issue's Editor's Choice, the first high resolution photoluminescence (PL) investigations of isotopically pure silicon are reported. The cover figure shows the PL spectrum of the no‐phonon transitions of an exciton bound to the neutral aluminum acceptor in 28Si, compared with the corresponding result from natural Si. It is seen that in the isotopically purified material the lines are shifted (as indicated by the horizontal arrow) and are sharper than in natural Si. Moreover, the splitting of the A0 ground state, as shown in the level scheme of the inset, is clearly absent in the 28Si sample, demonstrating that this splitting results from the random isotopic composition in natural Si. The paper is an invited presentation from the 10th International Conference on Shallow Level Centers in Semiconductors (SLCS‐10) held in Warsaw, Poland, 24‐27 July 2002.

This issue of phys. stat. sol. (b) contains a second paper selected as Editor's Choice, entitled “Tunable spin‐injection and magnetoconductance in a novel 2DEG‐ferromagnet structure” by Y. Jiang and M. B. A. Jalil [2].
Spin related effects in magnetic mesoscopic systems
Authors: Barnaś J. , Dugaev V. , Krompiewski S. , Martinek J. , Rudziński W. , Świrkowicz R. , Weymann I. , Wilczyński M.
Published: March 2003

Spin effects in transport properties of double‐barrier mesoscopic junctions are analyzed and their possible applications in spintronics devices are discussed. In a general case, external electrodes of the junctions are ferromagnetic and the central electrode is either a nonmagnetic metallic grain or a semiconducting quantum dot. Transport characteristics depend then on magnetic configuration of the system. When the spin relaxation time on the central electrode is sufficiently long, measurable spin effects can also occur in entirely nonmagnetic devices.
Ferromagnetic Kondo‐lattice model: Application to thin ferromagnetic and semiconducting local moment films
Authors: Nolting W. , Santos C.
Published: March 2003

We present a many‐body approach to the electronic and magnetic properties of the Kondo‐lattice model. This model is considered a candidate for the description of magnetic materials the characteristic properties of which are mainly determined by an exchange coupling of itinerant electrons to a system of localized magnetic moments. This coupling leads to a distinct temperature‐dependence of the electronic quasiparticle spectrum and to magnetic properties, as e.g. the Curie temperature TC or magnon dispersions, which are strongly influenced by the band electron selfenergy. The model studies are applied to thin ferromagnetic EuO(100) films. For a realistic description we present a multiband extension of the Kondo‐lattice model with a single‐electron part taken from a tight‐binding‐LMTO bandstructure calculation. The proposed method avoids the double counting of relevant interactions and takes into account the correct symmetry of atomic orbitals. The layer‐dependent magnetization as well as quasiparticle density of states are discussed as functions of the film thickness. For a 20‐layer film the existence of a surface state is predicted, which may lead to a temperature‐driven surface halfmetal‐insulator transition.
Ferromagnetic ordering in UFe0.5Ni0.5Al
Authors: Tran V. H. , Troć R. , André G. , Bourée F. , Baenitz M.
Published: March 2003

The alloy UFe0.5Ni0.5Al crystallizing in the hexagonal ZrNiAl‐type structure has been studied by means of neutron powder diffraction and specific heat measurements. The Ni atoms occupy preferentially the (1b) sites. The transition into a ferromagnetic state at TC ∼ 55 K reported previously is corroborated by the occurrence of specific heat anomaly and magnetic reflections. The magnetic structure consists of the ferromagnetic (001)‐planes with the magnetic moments parallel to the c‐axis. At 1.4 K, the ordered uranium moment is about 0.6 μB. The low‐temperature dependence of Cp may be described by an expression involving an energy gap in the magnon spectrum. The electronic coefficient of the specific heat is modestly enhanced and amounts to about 47 mJ/mol K2. This feature together with a small value of μord point to the strongly 5f–d hybridized character of the magnetism in UFe0.5Ni0.5Al.
Jahn–Teller effect and superexchange in half‐doped manganites
Authors: Sikora O. , Oleś A. M.
Published: March 2003

We investigate the stability of the charge exchange (CE) phase within a microscopic model which describes a single plane as in La0.5Sr1.5MnO4. The model includes Coulomb interactions (on‐site and intersite), the Jahn–Teller term and the superexchange interactions due to eg and t2g electrons. By investigating the phase diagram at T = 0 in mean‐field approximation we conclude that the superexchange interactions can stabilize the CE phase, but only if they are stronger than estimated from spectroscopy.
Electronic transport through large quantum dots in the Kondo regime
Authors: Stefański P. , Bułka B. R.
Published: March 2003

Conductance through a large two‐level quantum dot is investigated theoretically in the strong coupling regime. In large quantum dots the separation between discrete levels becomes smaller than the level width due to strong hybridization with electrodes. In such circumstances, apart from strong electronic correlations in the quantum dot, the indirect interaction between both the spatial levels comes into play. It takes place in lateral quantum dots, where the spatial level index is not conserved during the hybridization process with electrodes. This interaction shifts the Kondo resonance peak in the density of states out of the Fermi surface and alters its intensity. This feature can be observed in the differential conductance dependence vs. bias voltage. The virtual inter‐level mixing is suppressed for temperatures above the Kondo temperature of the system. The results of theoretical predictions are compared with the results of experimental conductance measurements performed on large quantum dots and some non‐typical conductance features are clarified.
Ground states of the spin‐1/2 Falicov–Kimball model
Authors: Lemański R. , Wojtkiewicz J.
Published: March 2003

The spin‐1/2 Falicov–Kimball model is analyzed perturbatively in the large U limit. In the case of 2D square lattice, the effective Hamiltonian up to terms proportional to U–3 has been obtained, and its ground states have been determined for a range of chemical potentials. The resulting phase diagram appeared to be qualitatively the same as that one for the spinless model. This is rather surprising result, because the effective Hamiltonians are quite different in the both cases.
Magnetization plateaux in S = 1 spin ladder
Authors: Sakai T. , Okazaki N. , Okamoto K. , Kindo K. , Narumi Y. , Hosokoshi Y. , Kato K. , Inoue K. , Goto T.
Published: March 2003

The experimental magnetization curve of the first synthesized S = 1 organic spin ladder compound BIP‐TENO is presented. It reveals a clear plateau at 1/4 of the saturation magnetization. We propose a mechanism of the 1/4 plateau formation based on the frustration due to third‐neighbor exchange interactions. We also compare the numerically calculated magnetization curve and susceptibility with the experimental results to estimate the exchange coupling constants.