bluuebunny/crossref_metadata_2025 huggingface dataset:
Unexpected Conformational Properties of 1‐Trifluoromethyl‐1‐Silacyclohexane, C5H10SiHCF3: Gas Electron Diffraction, Low‐Temperature NMR Spectropic Studies, and Quantum Chemical Calculations
Authors: Girichev Georgiy V. , Giricheva Nina I. , Bodi Andras , Gudnason Palmar I. , Jonsdottir Sigridur , Kvaran Agust , Arnason Ingvar , Oberhammer Heinz
Published: November 2006

The molecular structure of axial and equatorial conformers of 1‐trifluoromethyl‐1‐silacyclohexane, (C5H10SiHCF3), as well as the thermodynamic equilibrium between these species was investigated by means of gas electron diffraction (GED), dynamic nuclear magnetic resonance (DNMR) spectroscopy, and quantum chemical calculations (B3LYP, MP2, and CBS‐QB3). According to GED, the compound exists as a mixture of two Cs symmetry conformers possessing the chair conformation of the six‐membered ring and differing in the axial or equatorial position of the CF3 group (axial=58(12) mol %/equatorial=42(12) mol %) at T=293 K. This result is in a good agreement with the theoretical prediction. This is, however, in sharp contrast to the conformational properties of the cyclohexane analogue. The main structural feature for both conformers is the unusually long exocyclic bond length SiC 1.934(10) Å. A low‐temperature 19F NMR experiment results in an axial/equatorial ratio of 17(2) mol %:83(2) mol % at 113 K and a ΔG ≠ of 5.5(2) kcal mol−1. CBS‐QB3 calculations in the gas‐phase and solvation effect calculations using the PCM(B3LYP/6‐311G*) and IPCM(B3LYP/6‐311G*) models were applied to estimate the axial/equatorial ratio in the 100–300 K temperature range, which showed excellent agreement with the experimental results. The minimum energy pathways for the chair‐to‐chair inversion of trifluoromethylsilacyclohexane and methylsilacyclohexane were also calculated using the STQN(Path) method.
Metal‐Ion‐Coordinating Properties of the Dinucleotide 2′‐Deoxyguanylyl(5′→3′)‐2′‐deoxy‐5′‐guanylate (d(pGpG)3−): Isomeric Equilibria Including Macrochelated Complexes Relevant for Nucleic Acids
Authors: Knobloch Bernd , Sigel Helmut , Okruszek Andrzej , Sigel Roland K. O.
Published: November 2006

The interaction between divalent metal ions and nucleic acids is well known, yet knowledge about the strength of binding of labile metal ions at the various sites is very scarce. We have therefore studied the stabilities of complexes formed between the nucleic acid model d(pGpG) and the essential metal ions Mg2+ and Zn2+ as well as with the generally toxic ions Cd2+ and Pb2+ by potentiometric pH titrations; all four ions are of relevance in ribozyme chemistry. A comparison of the present results with earlier data obtained for M(pUpU)− complexes allows the conclusion that phosphate‐bound Mg2+ and Cd2+ form macrochelates by interaction with N7, whereas the also phosphate‐coordinated Pb2+ forms a 10‐membered chelate with the neighboring phosphate diester bridge. Zn2+ forms both types of chelates with formation degrees of about 91 % and 2.4 % for Zn[d(pGpG)]${{{- \hfill \atop {\rm cl}/{\rm N7}\hfill}}}$ and Zn[d(pGpG)]${{{- \hfill \atop {\rm cl}/{\rm PO}\hfill}}}$, respectively; the open form with Zn2+ bound only to the terminal phosphate group, Zn[d(pGpG)]${{{- \hfill \atop {\rm op}\hfill}}}$, amounts to about 6.8 %. The various intramolecular equilibria have also been quantified for the other metal ions. Zn2+, Cu2+, and Cd2+ also form macrochelates in the monoprotonated M[H;d(pGpG)] species (the proton being at the terminal phosphate group), that is, the metal ion at N7 interacts to some extent with the P(O)2(OH)− group. Thus, this study demonstrates that the coordinating properties of the various metal ions toward a pGpG unit in a nucleic acid differ: Mg2+, Zn2+, and Cd2+ have a significant tendency to bridge the distance between N7 and the phosphate group of a (d)GMP unit, although to various extents, whereas Pb2+ (and possibly Ca2+) prefer a pure phosphate coordination.
[40]Nonaphyrin(1.1.1.1.1.1.1.1.1) and Its Heterometallic Complexes with Palladium–Carbon Bonds
Authors: Kamimura Yiho , Shimizu Soji , Osuka Atsuhiro
Published: November 2006

meso‐Pentafluorophenyl‐ substituted [40]nonaphyrin(1.1.1.1.1.1.1.1.1) 3 has been prepared by using a stepwise ring‐size‐selective synthesis, and has been reduced with NaBH4 to [42]nonaphyrin(1.1.1.1.1.1.1.1.1) 5. Structurally, 3 is characterized by a figure‐of‐eight shape, consisting of a porphyrin‐like tetrapyrrolic segment and a hexaphyrin‐like hexapyrrolic segment, whereas 5 has been found to adopt a distorted nonplanar butterfly‐like shape. In the mono‐metal complexes 6 and 7, a ZnII or CuII ion is bound by the porphyrin‐like tetrapyrrolic segment, maintaining the overall structure of 3. Similarly to 3, complexes 6 and 7 are interconvertible with the corresponding complexes 9 and 10 through two‐electron reduction with NaBH4 and oxidation with DDQ. The metal‐free hexaphyrin‐like segments of 6 and 7 have been shown to serve as a suitable platform for the complexation of two palladium ions, providing hetero‐trinuclear metal complexes 11 (ZnII–PdII–PdII) and 13 (CuII–PdII–PdII) in high yields, in which the Zn or Cu ion resides at the same porphyrin‐like segment, and one Pd ion is bound in an NNCC fashion through double CH bond activation while the other is bound in an NNC fashion with single CH bond activation. Multi‐metal complexes 11, 12, and 13 exhibit small electrochemical HOMO–LUMO gaps (<0.6 eV), despite their nonplanar conformations.
Hyperfine Coupling Tensors of the Benzosemiquinone Radical Anion from Car–Parrinello Molecular Dynamics
Authors: Asher James R. , Kaupp Martin
Published: November 2006

Based on Car–Parrinello ab initio molecular dynamics simulations of the benzosemiquinone radical anion in both aqueous solution and the gas phase, density functional calculations provide the currently most refined EPR hyperfine coupling (HFC) tensors of semiquinone nuclei and solvent protons. For snapshots taken at regular intervals from the molecular dynamics trajectories, cluster models with different criteria for inclusion of water molecules and an additional continuum solvent model are used to analyse the HFCs. These models provide a detailed picture of the effects of dynamics and of different intermolecular interactions on the spin‐density distribution and HFC tensors. Comparison with static calculations allows an assessment of the importance of dynamical effects, and of error compensation in static DFT calculations. Solvent proton HFCs depend characteristically on the position relative to the semiquinone radical anion. A point‐dipolar model works well for in‐plane hydrogen‐bonded protons but deviates from the quantum chemical values for out‐of‐plane hydrogen bonding.
On the Origin of Red and Blue Shifts of XH and CH Stretching Vibrations in Formic Acid (Formate Ion) and Proton Donor Complexes
Authors: Tâme Parreira Renato Luis , Galembeck Sérgio Emanuel , Hobza Pavel
Published: November 2006

Complexes between formic acid or formate anion and various proton donors (HF, H2O, NH3, and CH4) are studied by the MP2 and B3LYP methods with the 6‐311++G(3df,3pd) basis set. Formation of a complex is characterized by electron‐density transfer from electron donor to ligands. This transfer is much larger with the formate anion, for which it exceeds 0.1 e. Electron‐density transfer from electron lone pairs of the electron donor is directed into σ* antibonding orbitals of XH bonds of the electron acceptor and leads to elongation of the bond and a red shift of the XH stretching frequency (standard H‐bonding). However, pronounced electron‐density transfer from electron lone pairs of the electron donor also leads to reorganization of the electron density in the electron donor, which results in changes in geometry and vibrational frequency. These changes are largest for the CH bonds of formic acid and formate anion, which do not participate in H‐bonding. The resulting blue shift of this stretching frequency is substantial and amounts to almost 35 and 170 cm−1, respectively.
pH Sensitivity of SiC Linked Organic Monolayers on Crystalline Silicon Surfaces
Authors: Faber Erik J. , Sparreboom Wouter , Groeneveld Wilrike , de Smet Louis C. P. M. , Bomer Johan , Olthuis Wouter , Zuilhof Han , Sudhölter Ernst J. R. , Bergveld Piet , van den Berg Albert
Published: November 2006

The electrochemical behavior of SiC linked organic monolayers is studied in electrolyte–insulator–Si devices, under conditions normally encountered in potentiometric biosensors, to gain fundamental knowledge on the behavior of such Si electrodes under practical conditions. This is done via titration experiments, Mott–Schottky data analysis, and data fitting using a site‐binding model. The results are compared with those of native SiO2 layers and native SiO2 layers modified with hexamethyldisilazane. All samples display pH sensitivity. The number of SiOH groups on the alkylated samples is calculated to be less than 0.7 % of that of a pure SiO2 insulator, which still causes a pH sensitivity of ≈25 mV per pH unit in the pH range: 4–7. The alkylated samples hardly suffer from response changes during up‐ and down‐going titrations, which indicates that very little oxide is additionally formed during the measurements. The pKa values of all samples with monolayers (4.0–4.4) are lower than that of native SiO2 (6.0). The long‐term drift (of approximately 1 mV h−1) is moderate. The results indicate that biosensors composed of alkylated Si substrates are feasible if a cross‐sensitivity towards pH in the sensor signal is taken into account.
Synthesis and Anion‐Selective Complexation of Homobenzylic Tripodal Thiourea Derivatives
Authors: Hisaki Ichiro , Sasaki Shin‐ichi , Hirose Keiji , Tobe Yoshito
Published: November 2006

Cryptand‐ and tripod‐type thiourea derivatives 4b and 5a–d, which have binding functionalities at the homobenzylic positions, were synthesized as possible neutral receptors toward anions with an expectation that the three binding sites work cooperatively to bind an anion selectively. 1H NMR spectroscopic monitoring of the titration of cryptand 4b with CH3CO2–, Cl–, and F– in CDCl2CDCl2 at 100 °C showed that the binding constants were considerably smaller than those of tripodal thiourea 5a, presumably owing to the presence of strong intramolecular hydrogen bonding in 4b. Complexation constants of tripodal receptors 5a–d with H2PO4–, CH3CO2–, Cl–, and Br– anions were evaluated by 1H NMR and/or UV/Vis spectroscopic analysis of the titration in DMSO. Though tripodal receptors 5a,b undergo complexation with phosphate anion in a 1:1 stoichiometry, their association constants were not as large as simple reference compound 14 probably because of the steric hindrance around the binding sites and the large entropy cost for cooperative binding. Receptor 5c exhibits complexation in a 1:2 stoichiometry with H2PO4– and CH3CO2–, whereas it forms 1:1 complexes with chloride and bromide anions because of the subtle balance between the steric hindrance and the binding ability. However, by increasing the acidity of the thiourea functionality, receptor 5d exhibited remarkably enhanced binding ability and selectivity toward H2PO4– compared to those of reference compound 15 presumably through cooperative complexation of the three binding sites to the guest anion. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Push‐Pull Oligomers with 2,2‐Dicyanovinyl Groups as Electron Acceptors
Authors: Meier Herbert , Mühling Bastian , Gerold Jürgen , Jacob Dominic , Oehlhof Annette
Published: November 2006

Three conjugated oligomer series with terminal donor–acceptor substitution were studied: oligo(1,4‐phenylenevinylene)s DAOPVs 4a–d (n = 1–4), oligo(1,4‐phenyleneethynylene)s DAOPEs 6a–d (n = 1–4) and oligo(2,5‐thienyleneethynylene)s DAOTEs 8a–e (n = 1–5). Dialkylamino or methoxy groups served as electron donors and 2,2‐dicyanovinyl groups as strong electron acceptors. The push‐pull effect polarizes the molecular chains – an effect which is documented by the splitting of the 13C chemical shifts of two carbon atoms of the double or triple bonds in the chain. For higher oligomers (n ≥ 3), the effect is mainly localized at the chain ends. The long‐wavelength absorption results in a charge‐transfer band which loses gradually its CT character since the intramolecular charge transfer (ICT) declines with increasing numbers n of repeat units (increasing chromophore extension, increasing distance D–A). As a consequence, theDAOPVs 4a–d and the DAOPEs 6a–d represent hypsochromic series, for which the λmax values decrease steadily from n = 1 to n = 4. This is also true for the DAOTE series 8a–e, but contrary to 4a–d and 6a–d the decrease is very small in the beginning [λmax(1) – λmax(2) = 1 nm] and grows with increasing n to λmax(4) – λmax(5) = 29 nm. Thus, series 8a–e represents an until now unknown type of conjugated push‐pull oligomers. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Alternative method to locate centre of rigidity in asymmetric buildings
Authors: Basu Dhiman , Jain Sudhir K.
Published: November 2006

Response of asymmetric buildup under earthquake excitation often involves lateral vibration coupled with torsional vibration. Floor slab is, in general, assumed as rigid along the in‐plane direction. Building code provisions to account for the torsional effect in static force procedure are based on centre of rigidity or shear centre of the building. A convenient procedure is developed here to locate the centre of rigidity or shear centre, which can be implemented, using any standard building analysis software. The procedure is applicable for orthogonal as well as non‐orthogonal building systems and accounts for all possible definitions of static eccentricity to compute the design response. An irregular building is analysed to illustrate the proposed methodology. Significant variation in member force resultants is observed due to different definitions of static eccentricity. Finally, a mathematical proof is presented to substantiate the applicability of the proposed procedure to a non‐orthogonal building. Copyright © 2006 John Wiley & Sons, Ltd.
Cover Picture: Macromol. Theory Simul. 9/2006
Authors: Feng Jian , Liu Honglai , Hu Ying
Published: November 2006

Cover:The morphology of symmetric diblock copolymer in a non‐neutral cylinder is diameter‐dependence. Increasing the radius, the morphology will transform from perpendicular lamellae into parallel lamellae and perpendicular lamellae in turn. Between different phases, an intermediate phase may exist. Further details can be found in the article by J. Feng, H. Liu,* and Y. Hu on page 674.
Deficiency of tenascin‐C attenuates liver fibrosis in immune‐mediated chronic hepatitis in mice
Authors: El‐Karef A , Yoshida T , Gabazza EC , Nishioka T , Inada H , Sakakura T , Imanaka‐Yoshida K
Published: November 2006

Tenascin‐C (TNC), an extracellular matrix glycoprotein, is upregulated in chronic liver disease. Here, we investigated the contribution of TNC to liver fibrogenesis by comparing immune‐mediated hepatitis in wild‐type (WT) and TNC‐null (TNKO) mice. Eight‐week‐old BALB/c mice received weekly intravenous injections of concanavalin A to induce hepatitis, and were sacrificed one week after the 3rd, 6th, 9th, and 12th injections. In WT livers, immunohistochemical staining revealed a gradual increase in TNC deposition. TNC mRNA levels also increased sequentially and peaked after the 9th injection. Collagen deposition, stained with picrosirius red, was significantly less intense in TNKO mice than in WT mice, and procollagen I and III transcripts were significantly upregulated in WT mice compared with TNKO mice. Inflammatory infiltrates were most prominent after the 3rd‐6th injections in both groups and were less intense in TNKO mice than in WT mice. Interferon‐γ, tumour necrosis factor‐α, and interleukin‐4 mRNA levels were significantly higher in WT mice than in TNKO mice, while activated hepatic stellate cells (HSCs) and myofibroblasts, a cellular source of TNC and procollagens, were more common in WT livers. Transforming growth factor (TGF)‐β1 mRNA expression was significantly upregulated in WT mice, but not in TNKO mice. In conclusion, TNC can promote liver fibrogenesis through enhancement of inflammatory response with cytokine upregulation, HSC recruitment, and TGF‐β expression during progression of hepatitis to fibrosis. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
The CADEUS study: methods and logistics
Authors: Depont F. , Fourrier A. , Merlière Y. , Droz C. , Amouretti M. , Bégaud B. , Bénichou J. , Moride Y. , Blin P. , Moore N.
Published: November 2006

Purpose

At the request of the French Health authorities, a study called CADEUS (COX‐2 inhibitors and NSAIDs: description of users) aimed to describe the users of cyclo‐oxygenase (COX)‐2 inhibitors and traditional non‐selective non‐steroidal anti‐inflammatory drugs (tNSAIDs). We report here the methodology, logistics and study design performances.

Methods

CADEUS is a cohort study designed to include 40 000 patients randomly sampled monthly in the French National Healthcare Insurance database, who received at least one dispensation of celecoxib, rofecoxib or tNSAIDs (1:1:2), from September 2003 to August 2004. Patients and prescribers were asked to fill a questionnaire on indication, medical history, risk factors and hospitalizations since drug acquisition. There was no reminder. For each respondent, healthcare resources used for the 6 months before and after inclusion were extracted from the database. Response rate, response delay, responders and non‐responders characteristics were assessed.

Results

Of the 222 879 patients and their prescribers contacted, 20.8% patients and 32.6% prescribers responded. Median response delay was 16 days for patients and 17 days for physicians. Factors associated with patient response were age, cohort, type of prescriber and period of inclusion.

Conclusion

This is the first study of this design in France, combining data from a claims database and direct patient and prescriber questionnaires. Copyright © 2006 John Wiley & Sons, Ltd.
Kinetics of the pH‐independent hydrolyses of 4‐nitrophenyl chloroformate and 4‐nitrophenyl heptafluorobutyrate in water‐acetonitrile mixtures: consequences of solvent composition and ester hydrophobicity
Authors: El Seoud Omar A. , Siviero Fábio
Published: November 2006

The pH‐independent hydrolyses of 4‐nitrophenyl chloroformate, NPCF and 4‐nitrophenyl heptafluorobutyrate, NPFB in aqueous acetonitrile were studied spectrophotometrically from 15 to 45 °C. The binary solvent composition covers water concentrations from 2.349 to 53.207 and from 2.745 to 53.333 mol L−1 for NPCF and NPFB, respectively. For both esters, the dependence of log (kobs), the observed rate constant, on log [water] is sigmoidal. The approximate kinetic orders with respect to water were found to be 2 and 3 for NPCF and NPFB, respectively. ΔG≠ gradually decreases as a function of increasing [water], due to a complex, quasi‐mirror image compensation of ΔH≠ and ΔS≠; both parameters increase. The structures of the transition states were probed by a proton inventory study, carried out in the presence of L2O mole fractions (L = H or D) of 0.190, 0.540, 0.890 and 0.180, 0.529, 0.890, for NPCF and NPFB, respectively. Plots of observed rate constants versus the atom fraction of deuterium in the solvent curve downward. Cyclic transition state models were fitted to the kinetic data; these models contain the ester and two water molecules (NPCF) or three water molecules (NPFB). Thus, the sigmoidal dependences of log (kobs) on log [water] are not due to a change in the number of water molecules in the transition states as a function of increasing [water]. The binary solvent mixture is micro‐heterogeneous; there exists two “micro‐domains,” one consists predominantly of coordinated water molecules, the other consists mostly of acetonitrile hydrogen‐bonded to water molecules. NPCF is 232 times more soluble in water than NPFB. That is, the former ester is dissolved in the outer, more polar periphery of these micro‐domains whereas the more hydrophobic NPFB is dissolved in their inner, less polar interiors. This conclusion is corroborated by comparing the dependence on log [water] of log [kobs], and of ET, the empirical solvent polarity parameter, as measured by solvatochromic probes of increasing hydrophobicity. Copyright © 2006 John Wiley & Sons, Ltd.
The effects of positioning on the Hering‐Breuer reflex in the preterm infant
Authors: Hand Ivan L. , Noble Lawrence , Geiss Donna
Published: November 2006

The aim of this study was to determine the effect of positioning on the Hering‐Breuer inflation reflex (HBIR) in the preterm infant. Seven, non‐intubated, premature infants, ranging in birthweight from 732 to 1450 g with post‐conceptual ages of 32–36 weeks were studied. In each infant, pulmonary function testing, including the HBIR was obtained using the SensorMedics 2600 during quiet sleep in the supine and prone position. The strength of the HBIR was quantified by the measurement of the percent prolongation of expiration after an occluded breath. Sleep states were categorized by the criteria of Prechtl. There was a significant difference in Hering‐Breuer activity in the prone position versus the supine position with a consistently stronger reflex in the prone position. The mean percent prolongation of expiration was 237 ± 108% in the prone position versus 95 ± 32% in the supine position. Analysis of the data, using paired t‐testing revealed a mean difference of 142 ± 119% between prone and supine positions (P = 0.028). Significant differences in the strength of the HBIR occur in relation to positioning in the preterm infant. Newborn positioning may affect pulmonary reflexes and may play a role in control of breathing. Pediatr Pulmonol. 2007; 42:37–40. © 2006 Wiley‐Liss, Inc.
Prospectively assessed incidence, severity, and determinants of respiratory symptoms in the first year of life
Authors: Latzin P. , Frey U. , Roiha H.L. , Baldwin D.N. , Regamey N. , Strippoli M.‐P.F. , Zwahlen M. , Kuehni C.E.
Published: November 2006

Respiratory symptoms are common in infancy. Nevertheless, few prospective birth cohort studies have studied the epidemiology of respiratory symptoms in normal infants. The aim of this study was to prospectively obtain reliable data on incidence, severity, and determinants of common respiratory symptoms (including cough and wheeze) in normal infants and to determine factors associated with these symptoms. In a prospective population‐based birth cohort, we assessed respiratory symptoms during the first year of life by weekly phone calls to the mothers. Poisson regression was used to examine the association between symptoms and various risk factors. In the first year of life, respiratory symptoms occurred in 181/195 infants (93%), more severe symptoms in 89 (46%). The average infant had respiratory symptoms for 4 weeks and 90% had symptoms for less than 12 weeks (range 0 to 23). Male sex, higher birth weight, maternal asthma, having older siblings and nursery care were associated with more, maternal hay fever with fewer respiratory symptoms. The association with prenatal maternal smoking decreased with time since birth. This study provides reliable data on the frequency of cough and wheeze during the first year of life in healthy infants; this may help in the interpretation of published hospital and community‐based studies. The apparently reduced risk in children of mothers with hayfever but no asthma, and the decreasing effect of prenatal smoke exposure over time illustrate the complexity of respiratory pathology in the first year of life. Pediatr Pulmonol. 2007; 42:41–50. © 2006 Wiley‐Liss, Inc.
Human metapneumovirus and respiratory syncytial virus infections in older children with cystic fibrosis
Authors: Garcia Daniel F. , Hiatt Peter W. , Jewell Alan , Schoonover Shauna L. , Cron Stanley G. , Riggs Mark , Grace Susan , Oermann Christopher M. , Piedra Pedro A.
Published: November 2006

Background:

Human metapneumovirus (hMPV) has been isolated from children with acute respiratory infection worldwide. Its epidemiology remains to be defined in children with cystic fibrosis (CF). We describe the epidemiology and clinical impact of hMPV in CF children and compared it to respiratory syncytial virus (RSV).

Methods:

CF children ages 7–18 years were studied prospectively during the 1998–1999 RSV season. Nasopharyngeal specimens were collected during acute respiratory illnesses and tested for respiratory viruses. Blood specimens were drawn early, mid, and end of the RSV season, and tested for serological evidence of hMPV and RSV infections. Rates of lower respiratory tract illnesses (LRTI) and hospitalizations for pulmonary exacerbations were compared during the time intervals they developed serological evidence of infection to their non‐infection intervals.

Results:

Six of 44 CF children had a virus positive respiratory illness in 56 LTRI events and 18 hospitalizations. Serological evidence of hMPV and RSV infections occurred in 16 and 20 CF children, respectively; 8 had infections with both viruses. A greater proportion of CF children had ≥1 LRTI during their infection intervals compared to their non‐infection intervals (13/25 vs. 5/25; P = 0.03). A trend for higher rates of LRTI was observed in the infection intervals compared to non‐infection intervals (9.5 ± 11.0 vs. 4.2 ± 9.9 per 1,000 child‐days; P = 0.06), and it was significantly greater with a more conservative estimate (one event per child per interval; 7.4 ± 7.7 vs. 2.6 ± 5.4 per 1,000 child‐days; P ≤0.01). No differences in hospitalizations rates were detected.

Conclusion:

The infection rates and clinical impact observed for hMPV were comparable to that for RSV in CF children 7–18 years of age. Pediatr Pulmonol. 2007; 42:66–74. © 2006 Wiley‐Liss, Inc.
Sequential alterations of tracheal mechanical properties in the neonatal lamb: Effect of mechanical ventilation
Authors: Miller Thomas L. , Zhu Yan , Altman Allison R. , Dysart Kevin , Shaffer Thomas H.
Published: November 2006

Alterations in neonatal airway mechanics resulting from ventilatory therapies are implicated in airway collapse and chronic disease. Quantifying the functional impact of mechanical ventilation (MV) on the neonatal airway and elucidating the time course of these changes will support development of protective therapies. The objective of this study was to test the hypothesis that conventional MV would result in decreased static and dynamic elastance of an isolated tracheal segment and thinning of the muscle (trachealis) region of the tracheal wall in a time dependent manner. Tracheal segments were isolated in newborn lambs spontaneously breathing through the distal trachea; segments were MV (n = 7; PIP/PEEP = 35/5 cmH2O; 40 breaths/min) or instrumented, non‐ventilated (SHAM; n = 7; PIP/PEEP = 0/0 cmH2O) for 4 hr. At baseline and hourly, tracheal segments were filled with saline, and static pressure–volume curves were constructed as the pressure response to stepwise volume infusions. Then, cross‐sectional ultrasound images were captured at 0 cmH2O on SHAM, and at 0 cmH2O, peak inspiratory pressure (PIP) and positive end expiratory pressure (PEEP), on MV tracheae for subsequent dimensional analysis. Tracheal elasticity indices were derived from static pressure–volume data, and during dynamic ventilation using ultrasound images to calculate the stress–strain relationships. Over 4 hr of MV, tracheal internal diameter (ID) increased (14%; P < 0.05). Markers of tracheal mechanical properties indicated a decrease in elasticity under both static (bulk modulus; 28%; P < 0.05) and dynamic (elastic modulus; 282 %; P < 0.05) conditions, indicating a significant alteration in elastic components. No time dependent changes were identified in dimensions or mechanical properties in the SHAM group. Conclusions: MV results in dimensional alterations that increased anatomical dead space and reduced static and dynamic elastance of the neonatal trachea. Pediatr Pulmonol. 2007; 42:141–149. © 2006 Wiley‐Liss, Inc.
Routine physiotherapy does not induce a cardiorespiratory training effect post‐stroke, regardless of walking ability
Authors: Kuys Suzanne , Brauer Sandra , Ada Louise
Published: November 2006

Background and Purpose. Cardiorespiratory fitness is increasingly being recognized as an impairment requiring physiotherapy intervention after stroke. The present study seeks to investigate if routine physiotherapy treatment is capable of inducing a cardiorespiratory training effect and if stroke patients attending physiotherapy who are unable to walk experience less cardiorespiratory stress during physiotherapy when compared to those who are able to walk. Method. A descriptive, observational study, with heart rate monitoring and video‐recording of physiotherapy rehabilitation, was conducted. Thirty consecutive stroke patients from a geriatric and rehabilitation unit of a tertiary metropolitan hospital, admitted for rehabilitation, and requiring physiotherapy were included in the study. The main measures of the study were duration (time) and intensity (percentage of heart rate reserve) of standing and walking activities during physiotherapy rehabilitation for non‐walking and walking stroke patients. Results. Stroke patients spent an average of 21 minutes participating in standing and walking activities that were capable of inducing a cardiorespiratory training effect. Stroke patients who were able to walk spent longer in these activities during physiotherapy rehabilitation than non‐walking stroke patients (p < 0.05). An average intensity of 24% heart rate reserve (HRR) during standing and walking activities was insufficient to result in a cardiorespiratory training effect, with a maximum of 35% achieved for the stroke patients able to walk and 30% for those unable to walk. Conclusions. Routine physiotherapy rehabilitation had insufficient duration and intensity to result in a cardiorespiratory training effect in our group of stroke patients. Copyright © 2006 John Wiley & Sons, Ltd.
Co‐variation of tests commonly used in stroke rehabilitation
Authors: Langhammer Birgitta , Stanghelle Johan Kvalvik
Published: November 2006

Background and Purpose. The aim of the present study was to analyse the co‐variation of different tests commonly used in stroke rehabilitation, and specifically used in a recent randomized, controlled study of two different physiotherapy models in stroke rehabilitation. Method. Correlations of the performed tests and recordings from previous work were studied. The test results from three‐month, one‐year and four‐year follow‐up were analysed in an SPSS Version 11 statistical package with Pearson and Spearman correlations. Results. There was an expected high correlation between the motor function tests, both based on partial and total scores. The correlations between Nottingham Health Profile Part 1 and Motor Assessment Scale (MAS), Sødring Motor Eevaluation Scale (SMES), the Berg Balance Scale (BBS) and Barthel Activities of Daily Living (ADL) index were low for all items except physical condition. The correlations between registered living conditions, assistive devices, recurrent stroke, motor function (MAS, SMES), ADL (Barthel ADL index) and balance (BBS) were high. The same variables showed weak or poor correlation to the Nottingham Health Profile (NHP). Conclusions. The co‐variations of motor function tests and functional tests were high, but the co‐variations of motor, functional and self‐reported life‐quality tests were poor. The patients rated themselves on a higher functional level in the self‐reported tests than was observed objectively in the performance‐based tests. A possible reason for this is that the patients may have been unaware they modified their performance to adjust for physical decline, and consequently overestimate their physical condition. This result underlines the importance of both performance‐based and self‐reported tests as complementary tools in a rehabilitation process. Copyright © 2006 John Wiley & Sons, Ltd.
Tests and finite element models of wood light‐frame shear walls with openings
Authors: Doudak G. , Smith I. , McClure G. , Mohammad M. , Lepper P.
Published: November 2006

Shear walls are the primary means by which low and medium rise wood light‐frame buildings resist effects of lateral loads caused by wind, seismic or other events. Traditionally, adequacy of shear walls has been a minor concern because wood light‐frame buildings tended to be small, their shapes were regular, the amount of external and interior walls available to resist lateral forces was considerable, and the number and extent of openings in walls was limited. In modern times however, changes in the range of wood‐based construction products used, changes in construction detailing, increased geometric irregularity of buildings, more open interiors, and more numerous and larger wall openings, has raised concerns about the lateral resistance of wood frame buildings. Shear walls and how they interact with the rest of the system needs to be properly understood. They should be analysed based on generalized engineering principles that are comprehensively validated.

This paper addresses proper understanding of wood light‐frame shear walls and engineering models for their analysis. Focus of analysis is on detailed finite element models suitable for representing shear walls with openings. Predictive abilities of models are verified against results of specially designed laboratory tests on shear wall segments containing a window or door opening and different hold‐down construction detailing. There is no intent that finite element models need be adopted by structural designers. Rather, the purpose of such models is that once rigorously verified they provide a benchmark against which the acceptability of simpler ‘design level’ models can be rationally assessed.

Very good agreement exists between finite element models presented here and test results for shear walls loaded to destruction, with correct prediction of failure mechanisms for different configurations. Both experiments and modelling clearly demonstrate that both stiffness and strength of shear walls reduces disproportionately in relation to the extent of openings in them. This suggests that neither simplistic conceptualization of how shear walls behave nor simple design practices will lead to solutions that are both economic and safe, across a broad range of situations. However, comparison of test results and model predictions with state‐of‐the‐art design code rules indicates that the code rules quite accurately predict actual strengths of the shear walls tested by the authors.

Further work is required to elucidate fully reliable design practices for buildings containing wood light‐frame shear walls. Emphasis within this will need be on the question of how to apportion lateral loads between various shear walls within a complete building.
Effect of exchange and dipolar interactions on the hysteresis of magnetic nanoparticle systems
Authors: Du H. F. , Du A.
Published: November 2006

The dependence of remanence and coercivity on the exchange and dipolar fields in a three‐dimensional simple cubic assembly of nanoparticles is studied by a modified Monte Carlo method in which the thermal fluctuation of magnetic moments of nanoparticles is completely considered. The long‐range dipolar interaction is summed directly in real space during the simulation. It is found that the dipolar field elongates the hysteresis loop horizontally, but the exchange field elongates it vertically. The competition between dipolar and exchange interparticle interactions leads to complex dependences of the remanence and coercivity on the exchange and dipolar fields at low temperature. Both remanence and coercivity decrease with the increase of temperature. Some results are in agreement with the experimental measurements. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Elementary energy bands in the band structure of AIV, AIIIBV crystals and superlattices built upon them
Authors: Bercha D. M. , Glukhov K. E. , Sznajder M.
Published: November 2006

A concept of the elementary energy bands was applied to interpret the electronic energy spectra of crystals from the cubic system and the superlattices (GaAs)M /AlAsM (M = 5, 10), (Si)10/(Ge)10 built upon them. Based upon this example, it was shown that the elementary energy bands concept elaborated in the empty‐lattice approximation allows one to predict the symmetry and topology of the valence band of artificial periodic systems as well as the spatial valence‐electron density distribution in a unit cell of those systems. A verification of this conclusion was confirmed by the ab‐initio band‐structure calculations of the superlattices mentioned above. An energy‐structural factor was found that joins two elementary energy bands characteristic for Td2 symmetry crystals into a physical complex that is related to the elementary energy band of the Oh7 symmetry crystals. This relationship between the elementary energy bands was utilized to find the actual Wyckoff position in the superlattice's unit cell responsible for the spatial electron density distribution. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High pressure studies of radiative recombination mechanisms in InN
Authors: Suski T. , Franssen G. , Teisseyre H. , Khachapuridze A. , Dmowski L. H. , Plesiewicz J. A. , Kamińska A. , Lu H. , Schaff W.
Published: November 2006

Reported hydrostatic pressure measurements of Hall electron concentration and Hall mobility of InN suggest the presence of a localized donor state in the conduction band. Since localized‐state emission is rather inefficient, the involvement of such a localized state would be highly inadvantageous for device applications. Pressure‐dependent photoluminescence (PL) experiments of InN epilayers show PL pressure coefficients dE E/dp of 30.7 ± 2.0 meV/GPa and 21.4 ± 3.0 meV/GPa for InN epilayers with electron concentration of ∼5 × 1018 cm–3 and ∼5 × 1017 cm–3, respectively. These values are comparable with the InN band gap pressure coefficient dE G/dp of ∼25–30 meV/GPa (indicating regular band‐to‐band emission), and differ significantly from the value of 5–10 meV/GPa that should be expected in the case of localized‐state emission. Therefore, in the presented experiments no evidence of the involvement of localized donor states in radiative recombination processes in InN is found. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Variation of the Jahn–Teller distortion with pressure in perovskite layers A2CuCl4. Influence on the charge‐transfer band
Authors: Rodríguez F. , Aguado F. , Valiente R. , Hanfland M. , Itiè J. P.
Published: November 2006

This work investigates the variation of the first charge‐transfer (CT) transition with pressure in the A2CuCl4 layered perovskites, in terms of structural changes, in particular, the local structure of the (CuCl6)4– octahedra. We show that pressure partially reduces the Jahn–Teller distortion. The decrease of the axial Cu–Cl distance, R ax, is an order of magnitude bigger than the decrease of the equatorial distance, R eq, but the in‐plane Cu–Cu distance reduction is almost twice that the sum of R ax and R eq, thus indicating pressure‐induce tilts. This phenomenon avoids suppression of the JT effect, keeping the (CuCl6)4– axial distortion above 10 GPa. Both the partial reduction of the JT distortion and tiliting can account for the CT redshift induced by pressure. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pressure and temperature tuning of laser diodes
Authors: Trzeciakowski W. , Bercha A. , Dybala F. , Bohdan R. , Adamiec P. , Mariani O.
Published: November 2006

Pressure and temperature change the bandgap of III–V semiconductors and therefore they shift the gain spectrum of laser diodes. With 20 kbar pressure (achievable in a liquid pressure cell) we can increase the energy of the laser emission by about 200 meV for lasers grown on GaAs, InP, or GaSb. The main physical limitation of pressure tuning for shorter wavelengths (i.e. between 600 and 800 nm) is the reduction of indirect gap (Γ–X) in the barriers and claddings of the laser structure, leading to strong increase of leakage and threshold currents. In this wavelength range temperature tuning seems more practical. Cooling down the laser from room temperature (300 K) to about 100 K we should be able to increase the emission energy by about 80 meV. The combination of pressure/temperature tuning with tuning by external grating turned out to combine the merits of both methods: wide spectral range, narrow linewidth, stable emission wavelength. The method seems promising although several issues still have to be addressed like the reliability of lasers and pressure cells after multiple pressure cycles, stability of coupling between the laser diode and fiber under high pressure etc. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of applied hydrostatic pressure on the e–h ground transition in self‐assembled InAs/GaAs quantum lens
Authors: Rodríguez Arezky H. , Duque C. A. , Trallero‐Giner C. , Vázquez G. J. , Castillo‐Mussot M. del , Porras‐Montenegro N.
Published: November 2006

A theoretical study of the e–h ground transition in self‐assembled InAs/GaAs quantum dots under hydrostatic pressure P is performed. The quantum dots have lens shape geometry of maximum height b and circular cross section or radius a with b < a. In the framework of the envelope‐function approximation the electronic states are evaluated as a function of the finite wall potentials, hydrostatic pressure and different lens geometry b /a. It is assumed that the increase of P keep constant the geometrical lens ratio b /a. The pressure dependence of all parameters entering into the description of the e–h transition have been taken into account. The results obtained taking the finite barrier are compared with the infinite model. It is shown that the variation of the e–h ground transition can be modelled using the simple infinite hard wall model with an effective dot radius as a fitting parameter. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The influence of pressure on the birefringence in semiconductor compounds ZnS, CuGaS2, and InPS4
Authors: Lavrentyev A. A. , Gabrelian B. V. , Kulagin B. B. , Nikiforov I. Ya. , Sobolev V. V.
Published: November 2006

Using the modified method of augmented plane waves and the code WIEN2k the calculations of the electron band structure, densities of electron states, and imaginary part of dielectric response function were carried out for different polarization of the vector of electrical field εxx and εzz for the semiconductor compounds ZnS, CuGaS2, and InPS4. The calculations were performed both for undisturbed crystals and for distorted crystals due to the applied pressure. The compounds studied have the similar crystallographic structures: ZnS – sphalerite, CuGaS2 – chalcopyrite, and InPS4 – twice defective chalcopyrite. It is known, that in cubic ZnS there is no birefringence, whereas in CuGaS2 and InPS4 there is one. But CuGaS2 has so called isotropic point (where εxx = εzz) in the visible optical range, and InPS4 has no such point. Our calculations of εxx and εzz have shown that in ZnS under the pressure the isotropic points arise, but in InPS4 they do not exist. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vibrational properties of InP under pressure: a molecular‐dynamics study
Authors: Branício Paulo S. , Rino José P.
Published: November 2006

Dynamical properties of InP in the zincblende (ZB) are investigated using isothermal–isobaric molecular‐dynamics simulations based on a proposed interaction potential for InP consisting of two‐ and three‐body terms. The two‐body term represents steric repulsion, Coulomb interactions due to charge transfer, induced charge–dipole interaction, and van der Waals dipole–dipole interaction. The three‐body term represents covalent bond bending and stretching. The model is fitted to reproduce crystalline lattice constant, cohesive energy, and the structural transition pressure from ZB to rocksalt. The effects of hydro‐ static pressure and temperature on the vibrational density‐of‐states, phonon anharmonicity, dynamic Debye–Waller factor, thermal expansion coefficient are described as well as the pressure induced structural phase transformation. Results are consistent with available experimental data, in particular the calculated equation of state and phonon density‐of‐states have very good agreement. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐pressure Raman study on type‐I germanium clathrate
Authors: Fukushima T. , Kume T. , Sasaki S. , Shimizu H. , Fukuoka H. , Yamanaka S.
Published: November 2006

Raman scattering measurements of the type‐I Ge clathrtate, Ba8Ge43, have been performed at 1 bar and room temperature, and under high‐pressures up to 22 GPa. Because of vacancies which exist in Ba8Ge43, the Raman spectrum at 1 bar was found to be different from that of Si clathrate. Low‐frequency vibrational modes associated with Ba atoms were found around 35–75 cm–1 and the Ge‐framework Raman bands were observed around 80–150 cm–1 comparable to the typical clathrate Ba8Si46. For these regions, spectral shapes are very similar to that of Ba8Si46. However, for the region above 150 cm–1, all the peaks were considerably weak in intensity, in contrast to Ba8Si46. In the data obtained at high pressures, the spectral changes were observed around 8.0 GPa and 22 GPa. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman study of semiconductor clathrates under high pressure
Authors: Kume T. , Fukushima T. , Sasaki S. , Shimizu H. , Fukuoka H. , Yamanaka S.
Published: November 2006

In order to gain an insight into the mechanism of the isostructural phase transition observed previously for Ba8Si46 compound, the high pressure Raman experiments have been performed for clathrate compounds of Ba8Au6Si40 and Ba8Ge3Si43 derivative from Ba8Si46 by substituting Si with other atoms. The Ba8Ge3Si43 clathrate indicated the occurrence of the phase transition at the same pressure as Ba8Si46 but, the Ba8Au6Si40 did not show up to 27 GPa. The present results suggest that a particular crystal site (6c site) plays an important role for the phase transition of the clathrate compounds. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Excitation and pressure effects on photoluminescence from dislocation engineered silicon material
Authors: Ishibashi Y. , Kobayashi T. , Prins A. D. , Nakahara J. , Lourenco M. A. , Gwilliam R. M. , Homewood K. P.
Published: November 2006

We report the influence of excitation wavelength and pressure effects on the photoluminescence (PL) of silicon light‐emitting diode material fabricated by boron ion implantation. The PL spectra show an anomalous increase in total intensity as temperature elevates, and this luminescence is found to be strongest with decreasing laser penetration depth away from the sample surface. The PL peak position shifts towards lower energy at a rate of –14 meV/GPa with increasing pressure. This rate agrees with earlier optical measurements on the band‐edge absorption of silicon, confirming that this luminescence is closely related to phonon‐assisted indirect band gap transitions. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low‐temperature electrical conductivity of heavily boron‐doped diamond single crystals
Authors: Blank V. D. , Buga S. G. , Terentiev S. A. , Kuznetsov M. S. , Nosukhin S. A. , Krechetov A. V. , Kul'bachinski V. A. , Kytin V. G. , Kytin G. A.
Published: November 2006

Single crystal diamonds 0.2–0.7 cm large doped with boron concentration 1019–1020 cm–3 were grown by temperature gradient method on the seed under pressure P = 5.5 GPa, temperature T = 1650 K. Temperature dependence of electrical resistance had been measured in the range of 0.5–297 K. Boltzmann activation type of conductivity and Mott's VRH law observed in samples in the temperature ranges ∼200–297 K and ∼70–297 K respectively. The temperature rise of conductivity in the range of ∼0.5–50 K for most heavily doped crystals was proportional to T 1/2. This rule indicates the vicinity of the electronic system to metal–insulator transition. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)