bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamics of Stress Bearing Particle Networks in Poly(propylene)/Alumina Nanohybrids
Authors: Acierno Domenico , Filippone Giovanni , Romeo Giovanni , Russo Pietro 
Published: March 2007

AbstractIn this work, we report about the relationships between the linear rheology and the microstructure of a polymer‐nanoparticle model system (i‐PP/Al2O3 nanospheres). Over a critical particle volume fraction, rheological evolutions during a quasi‐quiescent thermal annealing indicate the formation of a whole‐space‐spanning transient network of Al2O3 nanospheres, as confirmed by transmission electron microscopy. The dynamics of this network, responsible for the liquid‐like to solid‐like transition of the nanohybrid, have been investigated by means of rheological measurements. Once the network had formed, the application of large amplitude oscillatory shear progressively and irreversibly destroyed it, leading to a flow‐induced structure unable to contribute to the elasticity of the nanohybrid. Conversely, if the large deformation is applied to an unstructured sample, a solid‐like feature still emerges by ageing the sample. The resulting strength of such a nanohybrid, however, was lower than that obtainable without the application of large deformations. Energetic considerations may explain the transient nanoparticle network dynamics, strictly related to the bulk rheological properties.magnified image
On the Natural Draw Ratio of Semi‐Crystalline Polymers: Review of the Mechanical, Physical and Molecular Aspects
Authors: Séguéla Roland 
Published: March 2007

AbstractDrawing of semi‐crystalline polymers generally involves a necking phenomenon, which is often referred to as plastic instability. The draw ratio in the stable neck is called natural draw ratio. A review is made of papers dealing with the phenomenology of necking and endeavors to identify its physical origin. The destruction of the spherulitic structure that consists of chain‐folded lamellae involves a strain‐softening accompanied with a localization of the plastic deformation. In turn, the fibrillar transition that results from the lamellar fragmentation and subsequent rearrangement of the crystal blocks into microfibrils brings about a strain‐hardening, which stabilizes the plastic deformation. These competitive processes give rise to the natural draw ratio. The macromolecular network that consists of both chain entanglements and intercrystalline tie molecules appears to be a major factor of the neck stabilization. Theoretical approaches of the phenomenon are critically reviewed. Finally, the practical usefulness of the natural draw ratio is discussed with regard to predicting the long‐term mechanical behavior of high‐density polyethylene.magnified image
Recent Developments of New Components for Dental Adhesives and Composites
Authors: Moszner Norbert , Salz Ulrich 
Published: March 2007

AbstractThe currently used commercial self‐etching enamel‐dentin adhesives and restoratives composites are mainly based on a mixture of various monofunctional and cross‐linking dimethacrylates. New developments of enamel‐dentin adhesives concern the improvement of technique insensitivity and storage stability. Improvements of restorative composites are focused on the reduction of the polymerisation shrinkage, as well as the improvement of wear resistance, biocompatibility, and processing properties. In the past five years, many research efforts have been carried out to develop new monomers and tailor‐made components for filling materials, such as fillers or initiators. New phosphonic acid ether acrylates and cross‐linking bis(acrylamide)s enable the preparation of self‐etching enamel‐dentin adhesives with improved storage stability. With free‐radically polymerisable cyclic monomers, such as bicyclic cyclopropyl acrylates or cyclic allyl sulfides, low‐shrinkage storage‐stable restorative composites could be prepared. In case of the cationic polymerisable cyclic monomers, like siloxane‐based cycloaliphatic epoxides, the lower curing rate, stronger exothermic effect and lower curing depth compared to dimethacrylate‐based composites presently prevent their dental application. Designed methacrylates with tailor‐made properties and sol‐gel polycondensates can also contribute to the improvement of the currently used restorative composites. Radical polymerisable dental materials are initiated by light curing and by redox initiator systems. Under acidic conditions amine containing initiator systems are deactivated by acid‐base reaction. Non amine‐based initiators have to be developed for acidic monomer containing dental materials. The use of discrete nano‐filler particles mainly concerns the reinforcement and, in some cases, the increase of X‐ray opacity of composite filling materials.magnified image
Novel dual‐band filter using slotline and microstrip resonators
Authors: Zhang Xiu Yin , Chen Jian‐Xin , Xue Quan 
Published: March 2007

AbstractA novel dual‐band filter using slotline and microstrip resonators is proposed. By introducing slotline resonators on the ground of conventional microstrip resonator, the filter provides two transmission paths for RF signals. Each path generates its own passband. Both microstrip resonator and slotline resonators share the input and output ports without any external impedance‐matching network. Deep rejection between the two passbands is obtained due to a transmission zero located between them. The filter has the advantages of low insertion loss, compact size, and good selectivity. The simulated and measured results are presented and show good agreements. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1080–1081, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22348
Theoretical and experimental performance evaluation of all‐optical multiwavelength conversion by four‐wave mixing in fiber at 10/20/40 Gb/s for optical layer multicast
Authors: Yan N. , Teixeira A. , Silveira T. , Beleffi G. M. T. , Curti F. , Forin D. , Longa F. D. , Monroy I. T. , Monteiro P. , Koonen T. 
Published: March 2007

AbstractAll‐optical multiwavelength conversion (MWC) enables optical layer multicast without electronic processing. Wavelength conversion by four‐wave‐mixing (FWM) offers strict transparency in bit rate and modulation format. In this letter, a novel FWM MWC scheme is proposed, supported by theoretical analysis and experimental performance evaluation at 10/20/40 Gb/s. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49:1067–1071, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22358
A new wideband planar antenna with hyperpolar‐transformed Sierpinski carpet
Authors: Lee Gabsoo , Kim Youngsik 
Published: March 2007

AbstractThis paper presents a novel design of the printed hyperpolar‐transformed Sierpinski carpet (HSC) antenna. The design parameter and performance of the proposed monopole antenna are investigated and show that HSC geometry gives more freedom for wideband antenna design such as flare angle, scale factor, iteration number, etc. The simulated and measured results are well agreed and we can get octave bandwidth matching performance. The measured results of the return loss, radiation pattern, and antenna gain are also given. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1090–1092, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22361
Compact dual‐band slot‐antenna for WLAN applications
Authors: Tao J. , Cheng C. H. , Zhu H. B. 
Published: March 2007

AbstractA novel dual‐band slot‐antenna for WLAN applications is presented. The antenna is composed of two narrow slots fed by a microstrip‐line. In order to increase the impedance bandwidth of a narrow slot and keep its small size, a kind of stepped‐impedance (SI) slot is used. It has been investigated experimentally for its impedance bandwidth, radiation pattern, and gain over its operation frequency band. Result shows that the antenna has a 10% bandwidth from 2.25 to 2.53 GHz and a 15% bandwidth from 5.13 to 5.99 GHz. And a good radiation pattern and gain can be achieved over the frequency range. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1203–1204, 2007; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.22395
Direct noninvasive quantification of lactate and high energy phosphates simultaneously in exercising human skeletal muscle by localized magnetic resonance spectroscopy
Authors: Meyerspeer Martin , Kemp Graham J. , Mlynárik Vladimir , Krššák Martin , Szendroedi Julia , Nowotny Peter , Roden Michael , Moser Ewald 
Published: March 2007

AbstractA novel method based on interleaved localized 31P‐ and 1H MRS is presented, by which lactate accumulation and the accompanying changes in high energy phosphates in human skeletal muscle can be monitored simultaneously during exercise and recovery. Lactate is quantified using a localized double quantum filter suppressing the abundant lipid signals while taking into account orientation dependent signal modulations. Lactate concentration after ischemic exercise directly quantified by DQF 1H spectroscopy was 24 ± 3 mmol/L cell water, while 22 ± 3 mmol/L was expected on the basis of 31P MRS acquired simultaneously. Lactate concentration in a sample of porcine meat was estimated to be 40 ± 7 mmol/L by means of DQF quantitation, versus 39 ± 5 mmol/L by biochemical methods. Excellent agreement is shown between lactate concentrations measured noninvasively by 1H MRS, measured biochemically ex vivo, and inferred indirectly in vivo from changes in pH, Pi, and PCr as obtained from 31P MRS data. Magn Reson Med 57:654–660, 2007. © 2007 Wiley‐Liss, Inc.
Hip dGEMRIC in asymptomatic volunteers and patients with early osteoarthritis: The influence of timing after contrast injection
Authors: Tiderius Carl J. , Jessel Rebecca , Kim Young‐Jo , Burstein Deborah 
Published: March 2007

AbstractEight asymptomatic volunteers and 10 patients with early hip osteoarthritis (OA) were investigated with hip delayed gadolinium‐enhanced MRI of cartilage (dGEMRIC) at 30, 65, 100, and 135 min after IV injection with Gd‐DTPA2–. In asymptomatic volunteers there was a decrease in the dGEMRIC index (T1(Gd)) between 30 and 100 min. In patients the wash‐in of Gd‐DTPA2– was faster, with a low T1(Gd) at 30 min that did not change significantly over time. Therefore, earlier time points showed a larger separation in T1(Gd) between asymptomatic and OA hips, with more convenient timing logistics. However, T1(Gd) at 30 min had a larger standard deviation (SD) in the OA group, possibly due to variability of the steep slope of wash‐in. This sensitivity to the imaging window may be less desirable for longitudinal studies in which reproducibility is a concern. At all time points, T1(Gd) was 20–30% lower in patients than in asymptomatic volunteers (P < 0.003), which demonstrates the sensitivity of dGEMRIC to early hip OA. Magn Reson Med 57:803–805, 2007. © 2007 Wiley‐Liss, Inc.
Puzzle‐based storage systems
Authors: Gue Kevin R. , Kim Byung Soo 
Published: March 2007

AbstractWe introduce and develop models for a physical goods storage system based on the 15‐puzzle, a classic children's game in which 15 numbered tiles slide within a 4 × 4 grid. The objective of the game is to arrange the tiles in numerical sequence, starting from a random arrangement. For our purposes, the tiles represent totes, pallets, or even containers that must be stored very densely, and the objective is to maneuver items to an input–output point for retrieval or processing. We develop analytical results for storage configurations having a single empty location (as in the game) and experimental results for configurations with multiple empty locations. Designs with many empty locations can be made to form aisles, allowing us to compare puzzle‐based designs with traditional aisle‐based designs found in warehousing systems. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007
Polyurethane‐nanocomposite materials via in situ polymerization into organoclay interlayers
Authors: Rehab Ahmed , Akelah Ahmed , Agag Tarek , Shalaby Nasser 
Published: March 2007

AbstractNew nanocomposite materials based on polyurethane intercalated into organoclay layers have been synthesized via in situ polymerization. The syntheses of polyurethane–organoclay hybrid films were carried out by swelling the organoclay [12‐aminododecanoic acid montmorillonite] into different kinds of diols followed by addition of diisocyanate then casting in a film. The homogeneous dispersion of MMT in the polymer matrix is evidenced by scanning electron microscope and x‐ray diffraction, which showed the disappearance of the peak characteristic to d001 spacing. It was found that the presence of organoclay has improved the thermal, solvent resistance and mechanical properties. Also, the tensile strength is increased with increasing the organoclay contents to 20% by the ratio 182% related to the PU with 0% organoclay. On the contrary, the elongation has decreased with increasing the organoclay contents. Copyright © 2007 John Wiley & Sons, Ltd.
Laser ablation of SiO2for locally contacted Si solar cells with ultra‐short pulses
Authors: Engelhart Peter , Hermann Sonja , Neubert Tobias , Plagwitz Heiko , Grischke Rainer , Meyer Rüdiger , Klug Ulrich , Schoonderbeek Aart , Stute Uwe , Brendel Rolf 
Published: March 2007

AbstractWe apply ultra‐short pulse laser ablation to create local contact openings in thermally grown passivating SiO2layers. This technique can be used for locally contacting oxide passivated Si solar cells. We use an industrially feasible laser with a pulse duration of τpulse ∼ 10 ps. The specific contact resistance that we reach with evaporated aluminium on a 100 Ω/sq and P‐diffused emitter is in the range of 0·3–1 mΩ cm2. Ultra‐short pulse laser ablation is sufficiently damage free to abandon wet chemical etching after ablation. We measure an emitter saturation current density ofJ0e = (6·2 ± 1·6) × 10−13 A/cm2on the laser‐treated areas after a selective emitter diffusion withRsheet ∼ 20 Ω/sq into the ablated area; a value that is as low as that of reference samples that have the SiO2layer removed by HF‐etching. Thus, laser ablation of dielectrics with pulse durations of about 10 ps is well suited to fabricate high‐efficiency Si solar cells. Copyright © 2007 John Wiley & Sons, Ltd.
Surface heating by transvaginal transducers
Authors: Calvert J. , Duck F. , Clift S. , Azaime H. 
Published: March 2007

AbstractObjectiveThis safety study was designed to investigate tissue heating close to the surface of transvaginal ultrasound transducers, with the objective of assessing the validity of manufacturing safety standards set by the International Electrotechnical Commission (IEC).MethodsThe transducers investigated in this study were held in contact with a layered soft‐tissue mimicking material (TMM), and the temperature increase was measured at various depths using a miniature thermocouple. The temperature rise at 200 s was recorded, and the measured profiles of temperature rise with depth were compared with profiles predicted from both analytical and numeric models. Two transvaginal transducers of different manufacturers were investigated, operating in B‐mode imaging, color‐flow imaging and pulsed Doppler modes, using scanner settings giving acoustic output power towards the upper end of that available.ResultsThe greatest heating always occurred at the interface between the transducer and the TMM, and it reduced to about 0.1 times the surface temperature rise at a depth of 1 cm. A local maximum was observed in pulsed Doppler mode. A three‐dimensional finite‐element model which accounted for transducer dimensions gave a better prediction of temperature increase than a simple analytical model. The temperature profiles were compared with the depth of fetal tissue measured from a small survey of clinical scans.ConclusionsIt is provisionally concluded that the transducer surface temperature rise of 6 °C allowed to manufacturers by the IEC may give rise to an associated worst‐case contribution to temperature rise due to the transducer, in fetal tissue, of between 0.5 and 1 °C at 1‐cm depth. The contribution to tissue heating at 2 cm and deeper is negligible. Copyright © 2007 ISUOG. Published by John Wiley & Sons, Ltd.
Direct comparison of transcardiac difference between brain natriuretic peptide (BNP) and N‐terminal pro‐BNP in patients with chronic heart failure
Authors: Tsutamoto Takayoshi , Sakai Hiroshi , Ishikawa Chitose , Fujii Masanori , Tanaka Toshinari , Yamamoto Takashi , Takashima Hiroyuki , Ohnishi Masato , Wada Atsuyuki , Horie Minoru 
Published: March 2007

AbstractBackground:Direct comparison of transcardiac increase in brain natriuretic peptide (BNP) and NT‐pro‐BNP has not been performed previously.Aims:To evaluate the relation between BNP and NT‐pro‐BNP secretion, plasma levels and renal function.Methods:We measured the plasma levels of BNP and NT‐pro‐BNP in the aortic root and coronary sinus in 326 consecutive patients with chronic heart failure (CHF). Patients were divided into two groups [group I: estimated glomerular filtration rate (eGFR)≥60 mL/min and group II: eGFR<60mL/min].Results:The molar level of the transcardiac increase in NT‐pro‐BNP is lower than that of BNP. There were no differences in haemodynamics or the transcardiac gradient of BNP and NT‐pro‐BNP between group I and group II. The molar ratio of the plasma NT‐pro‐BNP to BNP was significantly higher in group II than in group I. By stepwise multivariate analyses, not only the left ventricular (LV) ejection fraction and LV end‐diastolic pressure, but also eGFR, LV mass index (LVMI) and haemoglobin were independent predictors of plasma NT‐pro‐BNP and BNP.Conclusion:The molar level of the transcardiac increase in NT‐pro‐BNP is lower than that of BNP; however, the influence of renal function on plasma NT‐pro‐BNP is greater than that on BNP.
Physical activity and cognitive health
Authors: Jedrziewski M. Kathryn , Lee Virginia M.-Y. , Trojanowski John Q. 
Published: March 2007

BackgroundThe industrialized nations are experiencing a demographic revolution caused by the continuing increase in longevity and the rapid rise in the percentage of the population older than 65 years. Interventions that promote healthy aging will continue to gain significance as efforts to delay disability and loss of function intensify.MethodsBecause physical activity has been implicated in promoting healthy aging, here we review a large body of research that examines physical activity and cognitive health. Specifically, we focus on the associations of physical activity with cognitive function and dementia, including prevention, delay, or slowing down of disease progression. Thus, we have prepared a descriptive review of the literature including various types of publications, prospective cohort, case‐control, clinical trial, and meta‐analysis articles published since 1999 in peer‐reviewed journals.ResultsOn the basis of currently available data, we conclude that the relative risk of cognitive decline with aging might diminish in individuals who are physically active; however, this has not been definitively demonstrated thus far.ConclusionsFurther research is needed to determine conclusively the effects of physical activity on cognitive function and dementia and to elucidate the basis for this linkage.
Subjective memory complaints, education, and risk of Alzheimer's disease
Authors: van Oijen Marieke , de Jong Frank Jan , Hofman Albert , Koudstaal Peter J. , Breteler Monique M. B. 
Published: March 2007

BackgroundSubjective memory complaints are common in the elderly. Although memory complaints are associated with an increased risk of Alzheimer's disease in persons with cognitive impairment as well as in persons with normal cognition, they are commonly considered of less importance than objective cognitive measures. We hypothesized that the clinical relevance of subjective memory complaints might vary with educational background.MethodsThe study was performed within the Rotterdam Study, a prospective population‐based cohort study among 7983 persons 55 years and older. Subjective memory complaints and level of education were assessed in the baseline interview (1990 to 1993). During a mean follow‐up of 9.0 years we identified 568 incident Alzheimer's disease patients. We estimated the association between subjective memory complaints and risk of dementia by means of Cox proportional hazard models.ResultsThe association between subjective memory complaints and risk of Alzheimer's disease varied across levels of education. The risk of Alzheimer's disease associated with subjective memory complaints was higher in highly educated persons (age‐ and sex‐adjusted hazard ratio, 2.33; 95% confidence interval [CI], 1.00–5.49) than in persons with a low education (age‐ and sex‐adjusted hazard ratio, 1.53; 95% CI, 1.15–2.05) (P value for interaction, .02). In highly educated persons without objective cognitive impairment (Mini‐Mental State Examination score, 29 or 30) the risk of Alzheimer's disease was highest (age‐ and sex‐adjusted hazard ratio, 2.98; 95% CI, 1.76–5.02).ConclusionsEspecially in persons with a high level of education who still perform well on formal cognitive tests, subjective memory complaints might be an important first sign of imminent Alzheimer's disease.
Lowland rainforest response to hydrological changes during the last 1500 years in Gabon, Western Equatorial Africa
Authors: Ngomanda Alfred , Jolly Dominique , Bentaleb Ilhem , Chepstow-Lusty Alex , Makaya M'voubou , Maley Jean , Fontugne Michel , Oslisly Richard , Rabenkogo Nicaise 
Published: March 2007

AbstractPollen and δ13CTOM data obtained from two contrasting lake sequences (Lakes Kamalété and Nguène), located 200 km apart in the lowland rainforest of Gabon, provide complementary local and regional 1500-yr records of high resolution (15–30 yr) vegetation change. A combination of aquatic, semi-aquatic and terrestrial pollen showed in both records that the tropical rainforest increased during periods of high rainfall and decreased during drought intervals. The strong fluctuations of water balance at decadal scale during the “Medieval Warm Period” (∼ 1100–800 cal yr BP) coincided with a noticeable increase in shade-intolerant taxa, indicating recurring rainforest canopy disturbance. The δ13CTOM signal showed high-amplitude variations in both records, which positively correlates with the rainforest dynamics and local vegetation changes. The similar trends in both the pollen and the δ13CTOM signals between these sites demonstrate the regional broadly synchronous timing of shifting hydrological conditions. The largely positive co-variation between strong fluctuations of hydrological conditions and changes in rainforest structure and composition indicate that regional climatic change is probably the driving force for major rainforest dynamics in Gabon. Any significant anthropogenic impact on vegetation has not been clearly identified, and this issue still needs to be resolved independently by obtaining detailed archeological records across the interval 1400–800 BP, which currently seem to be extremely rare or not easily available.