bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessment of Joule heating and its effects on electroosmotic flow and electrophoretic transport of solutes in microfluidic channels
Authors: Tang Gongyue , Yan Deguang , Yang Chun , Gong Haiqing , Chai John Chee , Lam Yee Cheong 
Published: February 2006

AbstractJoule heating is inevitable when an electric field is applied across a conducting medium. It would impose limitations on the performance of electrokinetic microfluidic devices. This article presents a 3‐D mathematical model for Joule heating and its effects on the EOF and electrophoretic transport of solutes in microfluidic channels. The governing equations were numerically solved using the finite‐volume method. Experiments were carried out to investigate the Joule heating associated phenomena and to verify the numerical models. A rhodamine B‐based thermometry technique was employed to measure the solution temperature distributions in microfluidic channels. The microparticle image velocimetry technique was used to measure the velocity profiles of EOF under the influence of Joule heating. The numerical solutions were compared with experimental results, and reasonable agreement was found. It is found that with the presence of Joule heating, the EOF velocity deviates from its normal “plug‐like” profile. The numerical simulations show that Joule heating not only accelerates the sample transport but also distorts the shape of the sample band.
A method for simultaneously determining the zeta potentials of the channel surface and the tracer particles using microparticle image velocimetry technique
Authors: Yan Deguang , Yang Chun , Nguyen Nam‐Trung , Huang Xiaoyang 
Published: February 2006

AbstractThe zeta potentials of channel surfaces and tracer particles are of importance to the design of electrokinetic microfluidic devices, the characterization of channel materials, and the quantification of the microparticle image velocimetry (microPIV) measurement of EOFs. A method is proposed to simultaneously measure the zeta potentials of the channel surface and the tracer particles in aqueous solutions using the microPIV technique. Through the measurement of the steady velocity distributions of the tracer particles in both open‐ and closed‐end rectangular microchannels under the same water chemistry condition, the electrophoretic velocity of the tracer particles and the EOF field of the microchannel are determined using the expressions derived in this study for the velocity distributions of charged tracer particles in the open‐ and closed‐end rectangular microchannels. Thus, the zeta potentials of the tracer particles and the channel surfaces are simultaneously obtained using the least‐square method to fit the microPIV measured velocity distribution of the tracer particles. Measurements were carried out with a microPIV system to determine the zeta potentials of the channel wall and the fluorescent tracer particles in deionized water and sodium chloride and boric acid solutions of various concentrations.
Oscillating electrolytes
Authors: Hruška Vlastimil , Jaroš Michal , Gaš Bohuslav 
Published: February 2006

AbstractChemical oscillations are driven by the gradient of the chemical potential so that they can appear in systems where the substances are not in chemical equilibrium. We show that under the influence of the electric field, concentrations of electrically charged substances in solutions can oscillate even if the system is in chemical equilibrium. The driving force here is not the gradient of the chemical potential but rather the gradient of the electric potential. Utilizing CE we found periodic structures invoked by the application of a constant driving voltage in BGEs possessing complex eigenmobilities. By analogy with the behavior of dynamic systems, complex eigenmobilities implicate that the system will be unstable. Instead of forming system zones (system peaks) in the separation channel (capillary) the originally uniform concentration of electrolyte constituents becomes periodically disturbed when the electric current passes through it.
Theoretical and nomenclatural considerations of capillary electrochromatography with monolithic stationary phases
Authors: Végvári Ákos , Guttman András 
Published: February 2006

AbstractDuring the past decade, CEC has been one of the few novel achievements in the field of separation science attracting a wide interest. The technology progress permitted the realization of the long‐sought idea to employ an electroosmotically driven flow through the columns improving the separations in terms of both resolution and efficiency. The early practical obstacles related to the use of conventional bead‐packed columns have been solved by the introduction of continuous beds, also known as monoliths. Hitherto, various synthesis approaches have been successfully developed producing monolithic beds in situ in capillary columns, sharing similar physical structure built up of tiny particles (in the sub‐µm range) that are covalently linked together and to the capillary wall. Parallel with the practical column technology studies, the theory of electrochromatography has been continuously developed, focusing on such basic issues as EOF characterization, separation efficiency, and peak dispersion effects. This review provides a short introduction to the theory of CEC with special attention to monolithic separation beds. The paper also summarizes the latest achievements in CEC and discusses the nomenclature, EOF characteristics, and some specific advantages of monolithic column technology.
Histochemical evidence of osteoclastic degradation of extracellular matrix in osteolytic metastasis originating from human lung small carcinoma (SBC‐5) cells
Authors: Li Minqi , Amizuka Norio , Takeuchi Kiichi , Freitas Paulo H.L. , Kawano Yoshiro , Hoshino Masaaki , Oda Kimimitsu , Nozawa‐Inoue Kayoko , Maeda Takeyasu 
Published: February 2006

AbstractThe aim of this study was to assess the dynamics of osteoclast migration and the degradation of unmineralized extracellular matrix in an osteolytic metastasis by examining a well‐standardized lung cancer metastasis model of nude mice. SBC‐5 human lung small carcinoma cells were injected into the left cardiac ventricle of 6‐week‐old BALB/c nu/nu mice under anesthesia. At 25–30 days after injection, the animals were sacrificed and their femora and/or tibiae were removed for histochemical analyses. Metastatic lesions were shown to occupy a considerable area extending from the metaphyses to the bone marrow region. Tartrate resistant acid phosphatase (TRAPase)‐positive osteoclasts were found in association with an alkaline phosphatase (ALPase)‐positive osteoblastic layer lining the bone surface, but could also be localized in the ALPase‐negative stromal tissues that border the tumor nodules. These stromal tissues were markedly positive for osteopontin, and contained a significant number of TRAPase‐positive osteoclasts expressing immunoreactivity for CD44. We thus speculated that, mediating its affinity for CD44, osteopontin may serve to facilitate osteoclastic migration after their formation associated with ALPase‐positive osteoblasts. We next examined the localization of cathepsin K and matrix metallo‐proteinase‐9 (MMP‐9) in osteoclasts. Osteoclasts adjacent to the bone surfaces were positive for both proteins, whereas those in the stromal tissues in the tumor nests showed only MMP‐9 immunoreactivity. Immunoelectron microscopy disclosed the presence of MMP‐9 in the Golgi apparatus and in vesicular structures at the baso‐lateral cytoplasmic region of the osteoclasts found in the stromal tissue. MMP‐9‐positive vesicular structures also contained fragmented extracellular materials. Thus, osteoclasts appear to either select an optimized function, namely secreting proteolytic enzymes from ruffled borders during bone resorption, or recognize the surrounding extracellular matrix by mediating osteopontin/CD44 interaction, and internalize the extracellular matrices. Microsc. Res. Tech. 69:73–83, 2006. © 2006 Wiley‐Liss, Inc.
Morphogenesis of the different types of photoreceptors of the chicken (Gallus domesticus) retina and the effect of amblyopia in neonatal chicken
Authors: Wai Maria Sen Mun , Lorke Dietrich Ernst , Kung Lai Sin , Yew David Tai Wai 
Published: February 2006

AbstractDespite the great variety in chicken photoreceptors, existing morphogenetic studies only deal with two types: rods and cones. We have therefore examined by scanning electron microscopy the first appearance and maturation of different retinal photoreceptors in 36 chicken embryos (Gallus domesticus), aged 5–19 days prehatching. On day 5 of incubation, chicken retinae were only composed of proliferating ventricular cells devoid of photoreceptors. On day 8, outer mitotic cells were separated from inner differentiating photoreceptors, by the transient layer of Chievitz. Ball‐like protrusions appeared at the ventricular surface, representing the first signs of photoreceptor inner segment formation. From day 10 onward, double cones, single cones, and rods could be clearly distinguished, and occasional cilia were detected at their tip. On day 12, inner segments had increased in length and diameter, and frequently carried a cilium representing the beginning of outer segment formation. On day 14, most photoreceptors displayed a distinct outer segment. On day 19, photoreceptors had essentially assumed adult morphology. Based on the shape of their outer segments, two subtypes of cones and three subtypes of double cones could be distinguished. Throughout development, we observed microvilli close to maturing photoreceptors, either originating from their lateral sides, from their tip, or from Müller cells. Microvillus density peaked between day 12 and 14, indicating an important role in photoreceptor morphogenesis. Unilateral occlusion of the eyes of posthatching chicken reduced the proportion of double cones to single cones in the retina, indicating dependence of retinal morphogenesis upon functional activity of visual cells. Microsc. Res. Tech. 69:99–107, 2006. © 2006 Wiley‐Liss, Inc.
Low‐field compact magnetic resonance imaging system for the hand and wrist in rheumatoid arthritis
Authors: Yoshioka Hiroshi , Ito Satoshi , Handa Shinya , Tomiha Sadanori , Kose Katsumi , Haishi Tomoyuki , Tsutsumi Akito , Sumida Takayuki 
Published: February 2006

AbstractPurposeTo investigate the feasibility of an originally developed compact MRI system for evaluating rheumatoid arthritis (RA), and determine its advantages and disadvantages as an imaging modality for evaluating RA.Materials and MethodsWe prospectively studied 13 healthy controls with no clinical symptoms of arthritis, and 13 patients with hand and wrist pains (including pain from RA) with a 0.2 T permanent‐magnet compact MR imager. All MR images were obtained while the subjects were in a sitting position. Coronal three‐dimensional spin‐echo T1‐weighted images and coronal two‐dimensional short tau inversion recovery (STIR) images were obtained with image matrix = 256 × 128 and field of view (FOV) = 20.48 cm. Plain radiograph findings and MRI findings of patients were compared.ResultsIn three of the patients with suspected early RA (N= 7), early RA was evaluated based on STIR images. All RA patients showed morphologic or signal intensity changes that allowed an evaluation of RA from MR findings. Four of five RA patients showed high signal intensity on STIR images in the wrist, proximal interphalangeal (PIP) joint, or metacarpophalangeal (MCP) joint that suggested synovitis. Multiple erosions in the hand and wrist were seen in four RA patients, with low signal intensity on T1‐weighted images.ConclusionRA was correctly evaluated, and early RA could be identified with the compact MRI system. However, the current system has limitations, such as the nonselective STIR sequence used and magnetic field inhomogeneity. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
B0 homogeneity throughout the monkey brain is strongly improved in the sphinx position as compared to the supine position
Authors: Valette Julien , Guillermier Martine , Boumezbeur Fawzi , Poupon Cyril , Amadon Alexis , Hantraye Philippe , Lebon Vincent 
Published: February 2006

AbstractPurposeTo map B0 distortions throughout the monkey brain in the two positions commonly used for NMR studies (the prone sphinx position and the supine position) in order to test the hypothesis that B0 homogeneity in the sphinx position is significantly improved as compared to the supine position.Materials and MethodsThree macaque monkeys were installed in the two positions in a 3T whole‐body MR system without shim correction. B0 maps were acquired using a 3D gradient double‐echo sequence, and field dispersion throughout the brain was quantified. In addition, field maps and localized 1H spectra were acquired after first‐order shimming was performed.ResultsThe field maps collected in the three animals were highly reproducible. B0 dispersion throughout the brain was typically two to three times greater in the supine position than in the sphinx position. Although first‐order shimming proved relatively more efficient in the supine position, B0 dispersion still remained greater in the supine than in the sphinx position. These findings can be explained by the thickness of outer brain tissues.ConclusionThis work demonstrates that the sphinx position is highly favorable in terms of B0 homogeneity. It should prove useful for NMR exploration of the monkey brain, particularly at high fields where B0 inhomogeneity associated with susceptibility artifacts is increased. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Calcium‐dependent volume reduction in regenerating ganglion cell axons in vitro
Authors: Edmonds B. T. , Koenig E. 
Published: February 2006

AbstractThe effects of increasing [Ca2+]i on volume regulatory behavior was investigated by phase‐contrast videomicroscopy in immature axons regenerating from goldfish retinal explants in vitro. Elevating [Ca2+]i by using EGTA‐buffered, ionomycin‐containing bathing media with either ≥ 100 μM [Ca2+]o or 1 μM [Ca2+]o with N‐methylglucamine substituted for Na+ caused axons to undergo a “syneresis.” The syneresis was characterized by a marked loss in volume and condensation of axoplasm, accompanied by a proliferation of lateral processes, which resulted ultimately in an arrest of visible particle transport. The random appearance of dynamic phase‐lucent axial protrusions in the distal axon, apparently caused by microtubules, was a frequent early manifestation. Syneresis was also produced by increasing the tonicity of the Cortland saline with sorbitol or treating axons with either valinomycin or with permeant cyclic AMP analogs in normal Cortland saline. In the latter case, extracellular Ca2+ was required. Preterminal axons showed an increase in phalloidin fluorescence after syneresis, suggesting polymerization and/or rearrangement of the actin cytoskeleton. Digitonin‐permeabilized axonal field models, which maintained good morphology and particle transport, failed to develop a syneresis even when [Ca2+]o was increased to 250 μM. Cytochalasin D did not interfere with the development of a syneresis, but did suppress the proliferation of lateral processes. Syneresis could be blocked by high [K+]o, putative antagonists of Ca2+‐activated K+ channels, or by calmidazolium, a calmodulin antagonist. The experimental findings suggest that cytoskeletal changes associated with volume reduction in growing retinal ganglion cell axons are secondary to a loss of cell water and that calcium/ calmodulin‐activated K+ channels very likely play a primary role in dehydration through the loss of K+ and osmotically obligated water.
Changes with aging in the levels of amino acids in rat CNS structural elements: III. Large neutral amino acids
Authors: Banay‐Schwartz M. , Lajtha A. , Palkovits M. 
Published: February 2006

AbstractThis paper reports the concentrations of valine, leucine, isoleucine, phenylalanine, and tyrosine as determined in 53 discrete brain areas of 3‐ and 29‐month‐old male Fischer 344 rats microdissected by the punch technique. The levels of other amino acids in the same areas are reported in other papers of this series. The essential amino acids reported in this paper showed great regional heterogeneity, with concentrations in areas of the highest content being 9 to 12 times higher than levels in areas of the lowest content. The relative distributions of these amino acids were fairly similar in that in a number of areas the amino acids were all at very high levels and in some other areas they were all at low levels, with a few exceptions. With aging, levels of some amino acids increased and levels of some others did not change, but the predominant change was a significant decrease in levels with age. The results indicate high regional heterogeneity in amino acid levels and in the changes of these levels with age.
Three‐dimensional structure of western Mediterranean cyclones
Authors: Campins Joan , Jansà Agustí , Genovés Ana 
Published: February 2006

AbstractAs many studies reveal, the western Mediterranean exhibits a high frequency of cyclone centres. Most of them are small and weak, but in some cases they are related to heavy rain and/or strong wind events. The climatological study of Mediterranean cyclones is the first crucial step to the better understanding and forecasting of such events.In the present paper, a method to objectively detect and track mean sea‐level (MSL) cyclones for the western Mediterranean is described. Furthermore, the three‐dimensional characterization of each MSL cyclone is performed by means of several parameters. This includes the vorticity, thermal and humidity fields at different pressure levels where the cyclone is detected, as well as the wind speed profile and the moist stability over the MSL cyclone. Both methodologies are illustrated and validated by a real case: an intense event of the well‐known Genoa cyclone. Detection, tracking and three‐dimensional characterization are applied to an 8‐year (from June 1995 to May 2003) database of numerical analyses. The result is a MSL cyclone database for the western Mediterranean with a description of their three‐dimensional structure. For a better analysis, cyclones are grouped in three different ways: by thickness, season and region of detection. Results show that western Mediterranean cyclones are located in specific geographical regions and that their location depends on the season. Several cyclones are weak and shallow, mainly because of thermal and/or orographic causes. On the contrary, other cyclones are large and intense and extend throughout the whole troposphere. Differences in cyclone structure depending on the location and season are also discussed. Copyright © 2006 Royal Meteorological Society.
Europe's 2003 heat wave: a satellite view of impacts and land–atmosphere feedbacks
Authors: Zaitchik Benjamin F. , Macalady Alison K. , Bonneau Laurent R. , Smith Ronald B. 
Published: February 2006

AbstractA combination of satellite imagery, meteorological station data, and the NCEP/NCAR reanalysis has been used to explore the spatial and temporal evolution of the 2003 heat wave in France, with focus on understanding the impacts and feedbacks at the land surface. Vegetation was severely affected across the study area, especially in a swath across central France that corresponds to the Western European Broadleaf (WEB) Forests ecological zone. The remotely sensed surface temperature anomaly was also greatest in this zone, peaking at +15.4 °C in August. On a finer spatial scale, both the vegetation and surface temperature anomalies were greater for crops and pastures than for forested lands. The heat wave was also associated with an anomalous surface forcing of air temperature. Relative to other years in record, satellite‐derived estimates of surface‐sensible heat flux indicate an enhancement of 48–61% (24.0–30.5 W m−2) in WEB during the August heat wave maximum. Longwave radiative heating of the planetary boundary layer (PBL) was enhanced by 10.5 W m−2 in WEB for the same period. The magnitude and spatial structure of this local heating is consistent with models of the late twenty‐first century climate in France, which predict a transitional climate zone that will become increasingly affected by summertime drought. Models of future climate also suggest that a soil‐moisture feedback on the surface energy balance might exacerbate summertime drought, and these proposed feedback mechanisms were tested using satellite‐derived heat budgets. Copyright © 2006 Royal Meteorological Society.
Novel pH Sensitive Block Copolymer Micelles for Solvent Free Drug Loading
Authors: Shim Woo Sun , Kim Sung Wan , Choi Eun‐Kyung , Park Heon‐Joo , Kim Jin‐Seok , Lee Doo Sung 
Published: February 2006

AbstractSummary: Novel pH sensitive biodegradable block copolymers (MPEG‐PDLLA‐OSM) composed of mono‐methoxy poly(ethylene glycol) (MPEG), poly (D,L‐lactide) (PDLLA) and sulfamethazine oligomer (OSM) were synthesized via ring‐opening polymerization and a dicyclohexyl carboimide (DCC) coupling reaction. These copolymers had a relatively low critical micelle concentration (CMC) due to the strong hydrophobic properties of non‐ionized OSM at pH 7.0. Also, the pH sensitive block copolymers showed the micelle‐unimer transition due to the ionization‐non‐ionization of OSM in the pH range (pH 7.2–8.4) above the CMC. Due to the pH sensitive properties of the block copolymer, the hydrophobic drug paclitaxel (PTX) was incorporated into a pH sensitive block copolymer micelle by the pH induced micellization method, without using an organic solvent. The block copolymer micelle prepared by pH induced micellization showed a relatively high PTX loading efficiency, and good stability for 2 d at 37 °C. Furthermore, the PTX loaded micelle showed a sustained release of PTX with a small burst in vitro over 2 d. The present results suggest that the pH induced micellization method due to the micelle‐unimer transition of the pH sensitive block copolymer would be a novel and valuable drug incorporation tool for hydrophobic and protein drugs, since no organic solvent is involved in the formulation.
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