bluuebunny/crossref_metadata_2025_split huggingface dataset:
Imaging brain activity during natural vision using CASL perfusion fMRI
Authors: Rao Hengyi , Wang Jiongjiong , Tang Kathy , Pan Wei , Detre John A. 
Published: October 2006

AbstractFunctional MRI (fMRI) has begun to be used to explore human brain activity during ecological and natural conditions. Arterial spin labeling (ASL) perfusion fMRI provides an appealing approach for imaging sustained brain activity during natural conditions because of its long‐term temporal stability and ability to noninvasively quantify absolute cerebral blood flow (CBF). The present study used ASL perfusion fMRI to measure brain activation patterns associated with natural vision by concurrently recording CBF and blood oxygen level‐dependent (BOLD) contrasts while subjects were freely viewing a cartoon movie. Reliable quantitative whole‐brain CBF values (∼60 mL/100g/min) as well as regional CBF values (45∼80 mL/100g/min) were measured during movie viewing and resting states. The perfusion contrast revealed CBF increases in multiple visual pathway areas and frontal areas, and CBF decreases in ventromedial frontal cortex and superior temporal cortex during movie viewing compared to resting states. Concurrent BOLD contrast revealed similar but weaker activation and deactivation patterns. Regression analyses of both CBF data and BOLD data showed significant associations between activation in the middle temporal (MT) region and subjects' perception of motion. Region of interest analysis based on a priori literature‐defined MT demonstrated significant monotonic stepwise associations between the intensity of motion perception and the CBF and BOLD signal changes. These results demonstrate the feasibility of using ASL perfusion fMRI for imaging both sustained and dynamic effects in neural activation during natural and ecologically valid situations, and support the notion of maintained functional segregation and specialization during natural vision. Hum Brain Mapp, 2006. © 2006 Wiley‐Liss, Inc.
Microfabrication of fractal polymeric structures for capillary morphogenesis: Applications in therapeutic angiogenesis and in the engineering of vascularized tissue
Authors: Bianchi F. , Rosi M. , Vozzi G. , Emanueli C. , Madeddu P. , Ahluwalia A. 
Published: October 2006

AbstractMicrofabrication techniques were combined with fractal algorithms to realize polymeric scaffolds resembling capillary networks. The scaffolds were seeded with human endothelial cells in monoculture as well as in coculture with human fibroblasts. To enhance the process of angiogenesis, endothelial cells were transfected with an adenoviral vector carrying the gene for human tissue kallikrien. The results demonstrate that both the presence of a structured scaffold as well as fibroblasts in coculture contribute synergically to the promotion of a metabolically active network. The fractal scaffolds have several possible applications for example in vascularized tissue engineering and therapeutic angiogenesis. A broader implication of these results is that cell‐extra cellular matrix and cell‐cell interactions cooperate dynamically both at a biochemical as well as microstructural level. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Growing tissue‐like constructs with Hep3B/HepG2 liver cells on PHBV microspheres of different sizes
Authors: Zhu Xin Hao , Wang Chi‐Hwa , Tong Yen Wah 
Published: October 2006

AbstractIn this study, an oil‐in‐water emulsion solvent evaporation technique was used to fabricate poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV, 8% PHV), microspheres as scaffold, to guide liver cell growth. Human hepatoma cell lines, HepG2 and Hep3B, were cultured in vitro on both the microspheres and polymer films. SEM and optical microscope images showed that multilayer cells were formed among the microspheres to bridge them together and developed into cell‐construct aggregates after 1 week of culture. MTT results showed that the cell proliferation on the microspheres was more than two times higher than that on the films after 12 days of culture. The cells seeded on microspheres secreted albumin 2–4 times more than that on the positive control after 1 week of culture, which indicated that this hepatic function was greatly improved by the aggregation of cells on microspheres. Although HepG2 failed to express P‐450 activity, this hepatic function was preserved when Hep3B cultured on microspheres. All the results indicated that PHBV microspheres are appropriate scaffolds for liver tissue engineering. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Safety evaluation of large external fixation clamps and frames in a magnetic resonance environment
Authors: Luechinger Roger , Boesiger Peter , Disegi John A. 
Published: October 2006

AbstractLarge orthopedic external fixation clamps and related components were evaluated for force, torque, and heating response when subjected to the strong electromagnetic fields of magnetic‐resonance (MR) imaging devices. Forces induced by a 3‐Tesla (T) MR scanner were compiled for newly designed nonmagnetic clamps and older clamps that contained ferromagnetic components. Heating trials were performed in a 1.5 and in a 3 T MR scanner with two assembled external fixation frames. Forces of the newly designed clamps were more than a factor 2 lower as the gravitational force on the device whereas, magnetic forces on the older devices showed over 10 times the force induced by earth acceleration of gravity. No torque effects could be found for the newly designed clamps. Temperature measurements at the tips of Schanz screws in the 1.5 T MR scanner showed a rise of 0.7°C for a pelvic frame and of 2.1°C for a diamond knee bridge frame when normalized to a specific absorption rate (SAR) of 2 W/kg. The normalized temperature increases in the 3 T MR scanner were 0.9°C for the pelvic frame and 1.1°C for the knee bridge frame. Large external fixation frames assembled with the newly designed clamps (390 Series Clamps), carbon fiber reinforced rods, and implant quality 316L stainless steel Schanz screws met prevailing force and torque limits when tested in a 3‐T field, and demonstrated temperature increase that met IEC‐60601 guidelines for extremities. The influence of frame‐induced eddy currents on the risk of peripheral nerve stimulation was not investigated. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Scattering from infinite rough tubular surfaces
Authors: Claeys Xavier , Haddar Houssem 
Published: October 2006

AbstractWe study the Helmholtz equation in the exterior of an infinite perturbed cylinder with a Dirichlet boundary condition. Existence and uniqueness of solutions are established using the variational technique introduced (SIAM J. Math. Anal. 2005; 37(2):598–618). We also provide stability estimates with explicit dependence of the constants in terms of the frequency and the perturbed cylinder thickness. Copyright © 2006 John Wiley & Sons, Ltd.
On existence and regularity of solutions for 2‐D micropolar fluid equations with periodic boundary conditions
Authors: Szopa Piotr 
Published: October 2006

AbstractIn this paper, we prove the existence and uniqueness of a global solution for 2‐D micropolar fluid equation with periodic boundary conditions. Then we restrict ourselves to the autonomous case and show the existence of a global attractor. Copyright © 2006 John Wiley & Sons, Ltd.
Coupled solution of heat and moisture flow in unsaturated clay barriers in a repository geometry
Authors: Chen G. J. , Ledesma A. 
Published: October 2006

AbstractAn analytical solution in the Laplace transform domain is obtained for the transient heat and moisture transport in an unsaturated clay buffer with a geometry simulating repository conditions. A numerical inversion scheme based on Crump's method is used to obtain the time‐domain solution. The coupled effect of thermally driven moisture transport is especially investigated because of its importance to alter the flow field in low‐permeability buffers. The practical background is based on the case of an engineering bentonite barrier placed in a drift excavated in rock in the context of underground disposal of high‐level radioactive waste. Parametric study has been performed to assess the effects of dimensionless geometry and material parameters on flow field. Despite the simplified assumptions required in order to obtain analytical expressions, the results incorporate the main mechanisms involved in the coupled thermo‐hydraulic (T–H) problem, and they may be eventually used for validation purposes. Copyright © 2006 John Wiley & Sons, Ltd.
Insect gonadotropic peptide hormones: some recent developments
Authors: Kuczer Mariola , Rosiński Grzegorz , Konopińska Danuta 
Published: October 2006

AbstractGonadotropic peptides are a new generation of peptide hormone regulators of insect reproduction. They have been isolated from ovaries, oviducts, or brains of insects. The subject of this paper is insect peptides that exert stimulatory or inhibitory effects on ovarian development and oocyte maturation. On the basis of the literature data and the results of our investigations, the structure and biological properties of different groups of peptides are presented. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
Quantitative Structure Vasodilatory Activity Relationship – Synthesis and “In Silico” and “In Vitro” Evaluation of Resveratrol‐Coumarin Hybrids
Authors: Vilar Santiago , Quezada Elías , Alcaide Carlos , Orallo Francisco , Santana Lourdes , Uriarte Eugenio 
Published: October 2006

AbstractThree theoretical models have been developed for the prediction of vasodilatory activity through a series of 2‐D molecular descriptors. A database of 501 compounds was selected from the literature and, of these compounds, 86 have vasodilatory activity. The QSAR models are capable of differentiating between active and inactive compounds with a level of classification greater than 80%. The models were used to predict the activity of a series of coumarins derived from resveratrol (a natural compound that is present in wine and has good vasodilatory activity) and led to the synthesis of three selected molecules. The sysnthesis of the resveratrol‐coumarin hybrids was efficiently achieved through a straightforward and direct route, and their vasodilatory activities were determined experimentally in rat aorta rings that were precontreated with noradrenaline. The theoretical results (“in silico” evaluation) show very good agreement with the experimental data (“in vitro” evaluation), which provide evidence of the reliability of the theoretical calculations and show their applicability in the rational design of new compounds. The compound predicted by the three models to be active (compound6) was confirmed to be the more active thantrans‐resveratrol.
Partnering with the state for sustainable development: Shell's experience in the Niger Delta, Nigeria
Authors: Ite Uwem E. 
Published: October 2006

AbstractThere is now growing consensus that moves towards sustainable development should involve constructive inputs from business, government and civil society. This paper critically examines the emerging partnership for human, institutional development and provision of physical infrastructure between the Shell Petroleum Development Company (SPDC) and the Niger Delta Development Commission (NDDC) in Nigeria. It argues that although SPDC is undertaking partnership with NDDC as part of its overall CSR strategy for the region its success will be influenced by four key challenges. These are political support for NDDC, funding constraints, public perceptions and expectations of NDDC, as well as institutional priorities. The implications of the findings for current debates on partnership and the role of business in society are highlighted. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment.
Coarse woody debris mass and nutrients in forest ecosystems of Korea
Authors: Kim Rae‐Hyun , Son Yowhan , Lim Jong Hwan , Lee Im Kyun , Seo Kyung Won , Koo Jin Woo , Noh Nam Jin , Ryu Soung‐Ryoul , Hong Sun Kee , Ihm Byung Sun 
Published: October 2006

AbstractCoarse woody debris (CWD) is an essential component of forests. However, quantification of both the mass and nutrient content of CWD within a given environment tends to be a fairly labor‐intensive proposition that requires long‐term studies to be conducted for viable data to be obtained. As a result, various aspects of CWD in forest ecosystems remain somewhat poorly understood. In this review, we have compiled all available estimates of CWD mass and nutrients from both coniferous and deciduous forests in Korea. The CWD mass data varied substantially by forest type, age, location, and sampling time, ranging from 1.5 to 24.5 Mg ha−1, and for the amount (kg ha−1) of nutrients in the CWD, ranging from 3.5 to 23.6 for nitrogen (N), 0.8 to 4.7 for phosphorus (P), 3.9 to 13.3 for potassium (K), 25.9 to 30.9 for calcium (Ca), 1.4 to 4.2 for magnesium (Mg), and 0.1 to 0.6 for sodium (Na). The mass of CWD transferred from live trees to the forest floor ranged between 0.1 and 4.9 Mg ha−1year−1, and these values were roughly equivalent to 26–42% of the annual litterfall inputs (2.5–10.8 Mg ha−1year−1) for mixedQuercusspp. forests within the relevant region. Annual nutrients inputs (kg ha−1year−1) through CWD decomposition were 0.7–1.6 for N, 0.04–0.3 for P, 0.3–1.0 for K, 1.7–3.1 for Ca, and 0.1–0.3 for Mg. Consequently, these results revealed that the ecological value of CWD for C and nutrient cycling was relatively insignificant. However, only a limited number of studies have been conducted on CWD in different coniferous or mixed deciduous forests in the region. As a direct result of this paucity of data, further long‐term studies on CWD mass and nutrients in a variety of forest types are required in order to be able to evaluate accurately the ecological value of CWD on biodiversity and physical properties in Korean forest ecosystems.
Evaluation of organic based corrosion inhibiting admixtures for reinforced concrete
Authors: Vishnudevan M. , Thangavel K. 
Published: October 2006

PurposeAdmixtures are materials that are added to concrete at some stage in its production to give concrete new properties whether in fluid or plastic conditions. The admixtures used in the construction industry are broadly classified into Mineral and Chemical admixtures. In recent years, the use of mineral and chemical admixtures in producing high performance concrete has increased significantly. The chemical reaction of cement with admixtures differs from material to material. Calcium nitrite based corrosion inhibiting admixtures have gained popularity for protection of reinforced and pre‐stressed concrete structures but calcium nitrite is not commercialized indigenously in India due to manufacturing difficulties. Hence, the objective of the present investigation was to study a novel corrosion inhibiting admixture system and to compare its effectiveness with sodium nitrite.Design/methodology/approachDi‐sodium phthalate, sodium orthophosphate and sodium nitrite‐based corrosion inhibiting admixtures were selected for the present investigation. The critical quantities of corrosion inhibiting additives were determined by accelerated laboratory tests. The following types of tests were conducted to evaluate the efficiency of the corrosion inhibiting admixtures: compressive strength of 100 × 100 × 100 mm concrete cubes after 3,7,14 and 28 days of curing, linear polarization resistance measurements, electrochemical impedance spectroscopy measurements, an accelerated 12 V controlled potential test.FindingsFrom the above tests, the inhibitor admixtured concrete not only improved in compressive strength but also increased its corrosion resistance properties. Of the inhibitors studied, di‐sodium phthalate showed superior corrosion resistance properties, compared to sodium nitrite.Originality/valueDi‐sodium phthalate may be considered a better substitute for calcium nitrite‐based corrosion inhibiting admixtures for durable concrete structures. This fulfils the objective of the investigation.
Gum arabic as a potential corrosion inhibitor for aluminium in alkaline medium and its adsorption characteristics
Authors: Umoren S.A. , Obot I.B. , Ebenso E.E. , Okafor P.C. , Ogbobe O. , Oguzie E.E. 
Published: October 2006

PurposeTo investigate the inhibitive effect of gum arabic (GA) for the corrosion of aluminium in alkaline (NaOH) medium and determine its adsorption characteristics. The present work is another trial to find a cheap and environmentally safe inhibitor for aluminium corrosion.Design/methodology/approachThe inhibition efficiency (%I) has been evaluated using the hydrogen evolution (via the gasometric assembly) and the thermometric methods at 30 and 40°C. The concentrations of GA (inhibitor) used were 0.1‐0.5 g/l and the concentrations of NaOH (the corrodent) were 0.1‐2.5 M. The mechanism of adsorption inhibition and type of adsorption isotherms were proposed from the trend of inhibition efficiency with temperature, Ea, ΔGads and Qads values.FindingsGA inhibited the corrosion of aluminium in NaOH solutions. The inhibition efficiency increased with increase in GA concentration and with increase in temperature. Phenomenon of chemical adsorption is proposed for the inhibition and the process followed the Langmuir and Freundlich adsorption isotherms. The results obtained in this study for the %I were comparable for the two methods used and were corroborated by kinetic and thermodynamic parameters evaluated from the experimental data.Research limitations/implicationsFurther investigations involving electrochemical studies such as polarization method will enlighten more on the mechanistic aspect of the corrosion inhibition.Originality/valueThis paper provides new information on the possible application of GA as an environmentally friendly corrosion inhibitor even in highly aggressive alkaline environments. It has not been published elsewhere.
Characterisation of high temperature oxide scales for plasma sprayed NiCrAlY coated Ni‐ and Fe‐based superalloys
Authors: Singh H. , Puri D. , Prakash S. , Srinivas M. 
Published: October 2006

PurposeTo characterise the high temperature oxide scales for some plasma sprayed NiCrAlY coated Ni‐ and Fe‐based superalloys.Design/methodology/approachNi‐22Cr‐10Al‐1Y metallic coatings were deposited on two Ni‐based superalloys; Superni 601 and Superni 718 and one Fe‐based superalloy; Superfer 800H by the shrouded plasma spray process. Oxidation studies were conducted on uncoated as well as plasma spray coated superalloys in air at 900°C under cyclic conditions for 50 cycles. Each cycle consisted of 1 h heating followed by 20 min of cooling in air. The thermogravimetric technique was used to approximate the kinetics of oxidation. X‐ray diffraction, SEM/EDAX and EPMA techniques were used to analyse the oxide scales.FindingsAll of the coated, as well as the uncoated, superalloys followed an alnost‐parabolic rate of oxidation. The NiCrAlY coating was found to be successful in maintaining its continuous contact with the superalloy substrates in all the cases. The oxide scales formed on the exposed NiCrAlY coated superalloys were found to be intact and spallation‐free. The main phases analysed for the coated superalloys were oxides of nickel, chromium and aluminium and spinel of nickel and chromium, which are expected to be useful for developing oxidation resistance at high temperatures.Practical implicationsThe coated superalloys showed remarkable cyclic oxidation resistance under simulated laboratory conditions. However, it is suggested that these coated superalloys also should be tested in actual industrial environments of boilers and gas turbines, etc. so as to obtain more practical and reliable oxidation data.Originality/valueThe knowledge of the reaction kinetics and the nature of the surface oxide scales formed during oxidation is important for evaluating the alloys for their use and degradation characteristics in high temperature applications such as steam boilers, furnace equipment, heat exchangers and piping in chemical industry, reformer, baffle plates/tubes in fertilizer plants, jet engines, pump bodies and parts.
Degradation behaviour of borosilicate glass: some studies
Authors: Manikandan Shobha , Jagannath  , Shrikhande V.K. , Kothiyal G.P. 
Published: October 2006

PurposeTo study the degradation behaviour of borosilicate glass, which is suitable for hermetic sealing with Molybdenum and Kovar (Fe/Co/Ni) alloys, as a function of concentration and temperature in both acidic and alkaline media for long durations, up to 160 h.Design/methodology/approachThe degradation (weight loss in mg/cm2 of the glass sample) was determined by immersing the glass sample in HCl and NaOH solutions at different temperatures for different periods extending up to 300 h. The damage to the glass surface was seen under an optical microscope and the chemical species on the corroded surface were identified by electron spectroscopy for chemical analysis.FindingsThe borosilicate glass, having the nominal composition 0.70 SiO2, 0.039 Na2O, 0.028 K2O, 0.21 B2O3, 0.01 Al2O3 was synthesized by melt and quench techniques. Degradation (corrosion) behaviour of this glass was investigated by immersing glass samples in 5 and 10 per cent HCl and 5 per cent NaOH solutions at different temperatures up to 90°C, for different periods and measuring dissolution rate (weight loss in mg/cm2 of the sample). Dissolution rates were found to be 5.47 mg/cm2 and 46.77 mg/cm2 in 5 per cent NaOH at 60 and 90°C, respectively, whereas they were comparatively low (2.59 and 5.80 mg/cm2 at 60 and 90°C, respectively, in 5 per cent HCl medium) after 160 h of total immersion period. The plot of dissolution rates against the temperatures showed the nonlinear behaviour at higher temperatures, probably due to the change in mechanism of corrosion. XPS studies exhibited the chemical species on the corroded surfaces. The optical microscopy of the corroded surface revealed that the corrosion mechanisms were different in acid and alkali media.Research limitations/implicationsThe degradation behaviour of borosilicate glass having a specific composition has been investigated as a function of concentration and temperature in both acid and alkaline media. The mixed alkali effect on the degradation behaviour may be studied by varying relative amount of Na2O and K2O in the glass composition.Practical implicationsThe glass composition under the present study has been used for fabrication of matched type glass‐to‐metal (GM) seals with kovar alloy. In this respect the present study is significant in deciding the environmental conditions for its use.Originality/valueThe degradation behaviour of borosilicate glass having alkali and alkaline earth metal oxides has been investigated as a function of concentration and temperature in both acid and alkali media. The findings in this paper have the potential implications in deciding the environmental conditions for use of GM seals fabricated using this glass.