bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting dispersion in porous media
Authors: Hunt A. G. , Skinner T. E. 
Published: June 2010

AbstractWe present a fundamental theory of solute dispersion in porous using (i) critical path analysis and cluster statistics of percolation theory far from the percolation threshold and (ii) the tortuosity and structure of large clusters near the percolation threshold. We use the simplest possible model of porous media, with a single length scale of heterogeneity in which the statistics of local conductances are uncorrelated. This combination of percolation‐based techniques allows comprehensive investigation and predictions concerning the process of dispersion. Our predictions, which ignore molecular diffusion and make minimal use of unknown parameters, account for results obtained in a comprehensive set of nearly 1100 experiments performed on systems ranging in size from centimeters to 100 km. The success of our simple treatment overturns many existing notions about transport in porous media, such as (1) multiscale heterogeneity must be accounted for in predictions (single scale is sufficient), (2) geologic correlations are of great importance (the randomness of percolation theory is more appropriate for prediction than the most complicated models in other frameworks), (3) geologic complexity is more important than statistical physics (exactly the reverse), (4) knowledge of the subsurface is more important than knowledge of the initial conditions of the plume (the latter is critical, the former may be virtually irrelevant), (5) diffusion is dominant over advection (diffusion appears seldom to be relevant at all), (6) fracture networks are fundamentally different, and more complex, than porous media (the two are mostly equivalent), (7) the fractal structure of the medium is relevant to power‐law behavior of the dispersion (in fact, at short times it is the heterogeneity of the medium, while at long times it is the fractal structure of the critical paths), and (8) there is a relation between an increase in dispersion with scale and a similar increase in the hydraulic conductivity (in fact the present model is consistent with both a diminishing hydraulic conductivity and a diminishing solute velocity with increasing spatial scale). © 2009 Wiley Periodicals, Inc. Complexity, 16,43–55, 2010
Detection of TiO2 nanoparticles in cells by flow cytometry
Authors: Zucker R. M. , Massaro E. J. , Sanders K. M. , Degn L. L. , Boyes W. K. 
Published: June 2010

AbstractEvaluation of the potential hazard of man‐made nanomaterials has been hampered by a limited ability to observe and measure nanoparticles in cells. In this study, different concentrations of TiO2 nanoparticles were suspended in cell culture medium. The suspension was then sonicated and characterized by dynamic light scattering and microscopy. Cultured human‐derived retinal pigment epithelial cells (ARPE‐19) were incubated with TiO2 nanoparticles at 0, 0.1, 0.3, 1, 3, 10, and 30 μg/ml for 24 hours. Cellular reactions to nanoparticles were evaluated using flow cytometry and dark field microscopy. A FACSCalibur™ flow cytometer was used to measure changes in light scatter after nanoparticle incubation. Both the side scatter and forward scatter changed substantially in response to the TiO2. From 0.1 to 30 μg/ml TiO2, the side scatter increased sequentially while the forward scatter decreased, presumably due to substantial light reflection by the TiO2 particles. Based on the parameters of morphology and the calcein‐AM/propidium iodide viability assay, TiO2 concentrations below 30 μg/ml TiO2 caused minimal cytotoxicity. Microscopic analysis was done on the same cells using an E‐800 Nikon microscope containing a xenon light source and special dark field objectives. At the lowest concentrations of TiO2 (0.1–0.3 μg/ml), the flow cytometer could detect as few as 5–10 nanoparticles per cell due to intense light scattering by TiO2. Rings of concentrated nanoparticles were observed around the nuclei in the vicinity of the endoplasmic reticulum at higher concentrations. These data suggest that the uptake of nanoparticles within cells can be monitored with flow cytometry and confirmed by dark field microscopy. This approach may help fulfill a critical need for the scientific community to assess the relationship between nanoparticle dose and cellular toxicity Such experiments could potentially be performed more quickly and easily using the flow cytometer to measure both nanoparticle uptake and cellular health. Published 2010 Wiley‐Liss, Inc.
Weak Ferromagnetism Caused by a 2D Effect in Two New Cobalt(II)– and Nickel(II)–1,2‐Bis(4‐pyridyl)ethane (bpa) Polynuclear Compounds
Authors: de la Pinta Noelia , Madariaga Gotzon , Lezama Luis , Fidalgo M. Luz , Cortés Roberto 
Published: June 2010

AbstractThe combination of bpa [1,2‐bis(4‐pyridyl)ethane] with the pseudohalide cyanato (NCO–) ligand leads to the preparation of two new isomorphous compounds exhibiting the general formula [M(NCO)2(bpa)2]n [M = Co (1) and M = Ni (2)]. Both compounds consist of M–(gauche‐bpa)2–M chains linked by hydrogen bonds to give a global 2D network. CoII and NiII ions are octahedrally coordinated to four bpa ligands and two terminal NCO groups. The two compounds exhibit slight antiferromagnetic interactions through bpa groups and a 2D effect leading to a ferromagnetic component.
Oxidative Nucleophilic Substitution of Hydrogen in Nitroarenes with Carbanions of Protected Serine and Threonine Esters
Authors: Sulikowski Daniel , Mąkosza Mieczysław 
Published: June 2010

AbstractThe reactions of carbanions of protected serine and threonine esters with nitroarenes were studied. The main process involves the addition of the carbanions to the para position of the nitroarenes, which is occupied by a hydrogen atom, to form σH adducts that are subsequently oxidized by 2,3‐dichloro‐5,6‐dicyanobenzoquinone to give p‐nitroaryl derivatives of the protected serine and threonine. Oxidation of the σH adducts with dimethyldioxirane resulted in the formation of the corresponding p‐hydroxyaryl derivatives of these amino acids. Addition of the carbanions of the protected threonine ester is a highly stereoselective process controlled by the second chiral center of threonine.
Function of OPG as a traffic regulator for RANKL is crucial for controlled osteoclastogenesis
Authors: Aoki Shigeki , Honma Masashi , Kariya Yoshiaki , Nakamichi Yuko , Ninomiya Tadashi , Takahashi Naoyuki , Udagawa Nobuyuki , Suzuki Hiroshi 
Published: June 2010

Abstract
The amount of the receptor activator of NF-κB ligand (RANKL) on the osteoblastic cell surface is considered to determine the magnitude of the signal input to osteoclast precursors and the degree of osteoclastogenesis. Previously, we have shown that RANKL is localized predominantly in lysosomal organelles, but little is found on the osteoblastic cell surface, and consequently, the regulated subcellular trafficking of RANKL in osteoblastic cells is important for controlled osteoclastogenesis. Here we have examined the involvement of osteoprotegerin (OPG), which is currently recognized as a decoy receptor for RANKL, in the regulation of RANKL behavior. It was suggested that OPG already makes a complex with RANKL in the Golgi apparatus and that the complex formation is necessary for RANKL sorting to the secretory lysosomes. It was also shown that each structural domain of OPG is indispensable for exerting OPG function as a traffic regulator. In particular, the latter domains of OPG, whose physiologic functions have been unclear, were indicated to sort RANKL molecules to lysosomes from the Golgi apparatus. In addition, the overexpression of RANK-OPG chimeric protein, which retained OPG function as a decoy receptor but lost the function as a traffic regulator, inhibited endogenous OPG function as a traffic regulator selectively in osteoblastic cells and resulted in the upregulation of osteoclastogenic ability despite the increased number of decoy receptor molecules. Conclusively, OPG function as a traffic regulator for RANKL is crucial for regulating osteoclastogenesis at least as well as that as a decoy receptor. © 2010 American Society for Bone and Mineral Research.
Options for determination of 2‐D distribution of collagen fibrils in transmission electron micrographs—Application to the mammalian corneal stroma
Authors: Doughty Michael J. 
Published: June 2010

AbstractAims: To assess methods for both measurement of and comparison between fibril spacing arrangement in transmission electron micrograph (TEM) images of collagen fibrils. Methods: Rabbit corneas were glutaraldhyde fixed, treated with osmium tetroxide and then thin sections stained with aqueous phosphotungstic acid. TEM images, at 28,000 magnification, of collagen fibrils in cross section were projected at a final magnification close to 250,000 to obtain overlays. Fibril centers were marked and the relative position of all fibrils measured either from a cluster of fibrils within a fixed region of interest (ROI) or by using a variable sequential ROI across the micrograph. The 2‐D organization of the interfibril distance (IFD) data were analyzed using a radial distribution analysis and the difference in outcome statistically compared. Results: Repeated measures of IFDs provides data on the nearest neighbor distance within a fixed or sequential ROI of close to 48 nm and provides a numerical descriptor of the radial positions of all other fibril centers. From the set of radial positions (IFD) data, simple statistical comparisons can be made to both assess location‐to‐location and sample‐to‐sample variability. The sequential use of an ROI of fibril arrays however provide a more complete and accurate numerical descriptor. Conclusions: Methods are presented that will allow for assessment of the nearest neighbors distances and the overall 2‐D pattern of collagen fibrils in electron micrographs. The sets of IFDs and their pattern can be compared using simple statistical analyses. Microsc. Res. Tech., 2010. © 2010 Wiley‐Liss, Inc.
Enameloid microstructure of some Cretaceous Hexanchiformes and Synechodontiformes (Chondrichthyes, Neoselachii): New structures and systematic implications
Authors: Guinot Guillaume , Cappetta Henri 
Published: June 2010

AbstractModern neoselachian sharks may be separated from more basal relatives by the presence of tooth enameloid comprising three layers. Although enameloid microstructure studies were mostly used in the aim of differentiating supposed basal neoselachians from hybodonts, differences in the enameloid organization among neoselachians have been recognized suggesting the potential for use of enameloid microstructure as a phylogenetic tool within the neoselachian sharks. The enameloid microstructure of five taxa of neoselachian sharks belonging to two orders, the Hexanchiformes and Synechodontiformes, has been studied. The Hexanchiformes are a monophyletic order with extant representatives, whereas the extinct Synechodontiformes have been considered as monophyletic, paraphyletic, or polyphyletic by different authors. This study has revealed numerous new enameloid microstructures such as amalgamated crystallites in the internal units [parallel‐bundled enameloid (PBE) and tangled‐bundled enameloid], cavities at the shiny‐layered enameloid (SLE)/PBE boundary, radial furrows in the PBE, as well as different original organizations at the base of the crown and in the PBE at the level of the cutting edges.Pachyhexanchus pockrandti(Hexanchiforme) andWelcommia bodeurihave the most of the features in common and they share more characters with those ofParaorthacodussp. andSphenodussp. than withSynechodussp. Microsc. Res. Tech., 2010. © 2010 Wiley‐Liss, Inc.
The effect of exercise training on the metabolic interaction between feeding and locomotion in the juvenile southern catfish (Silurus meridionalis Chen)
Authors: Li Xiu‐Ming , Cao Zhen‐Dong , Fu Shi‐Jian 
Published: June 2010

AbstractThe southern catfish exhibits the largest decrease in critical swimming speeds (Ucrit) during digestion among the fish species that have been investigated. To test whether the maximum metabolic capacity of the southern catfish was improved after exercise training to alleviate the competitive interaction between digestion and swimming, we measured postprandial metabolic responses, Ucrit and oxygen consumption rates (MO2) during swimming in both fasting and digesting fish. Twenty‐one days of training (50 min swimming at 60% Ucrit followed by 10 min chasing) did not produce significant differences in resting MO2 (MO2rest) or postprandial peak MO2 (MO2peak). However, it did result in a significant decrease in energy expenditure during digestion. Feeding caused a significant decrease in Ucrit and an increase in active MO2 (MO2active), whereas training caused a significant increase in Ucrit but no significant change in MO2active. Neither digestion nor training had a significant effect on metabolic scope (MO2active−MO2rest). Training had no interactive effect on postprandial changes in any measured variable, so we conclude that training did not alleviate the competitive interaction between digestion and swimming. Our results suggest that: (1) the metabolic capacity of nontrained fish cannot support the metabolic demands of both digestion and locomotion simultaneously, and swimming metabolism, therefore, is sacrificed to sustain digestion when feeding and locomotion are combined (digestion‐prioritization mode); (2) the metabolic capacity and metabolic mode of competition did not change after training, but trained fish did exhibit improved swimming performance, possibly due to their increased rate of O2 extraction. J. Exp. Zool. 313A:557–563, 2010. © 2010 Wiley‐Liss, Inc.
Dissociation mechanisms and implication for the presence of multiple conformations for peptide ions with arginine at the C‐terminus: time‐resolved photodissociation study
Authors: Yoon So Hee , Moon Jeong Hee , Kim Myung Soo 
Published: June 2010

AbstractTime‐resolved photodissociation (PD) patterns of singly protonated peptides with arginine at the C‐terminus (C‐arg peptide ions) have been used to classify the dissociation channels into two categories, i.e. high‐energy channels generating v, w and x and low‐energy ones generating b, y and z. x + 1 formed by CαCO cleavage seems to be the intermediate ion in high‐energy channels just as a + 1 is for N‐arg peptide ions. Difference in time‐resolved pattern indicates that the two sets of channels, high‐ and low‐energy ones, are not in direct competition. Noncompetitive dissociation is also indicated by the observation of anomalous effect of matrix used in matrix‐assisted laser desorption ionization, a cooler matrix generating more high‐energy product ions both in spontaneous dissociation and in PD. Results from detailed investigation suggest that the two sets of channels start from two (or more) different conformations. Copyright © 2010 John Wiley & Sons, Ltd.
Gallic acid induces G2/M phase cell cycle arrest via regulating 14‐3‐3β release from Cdc25C and Chk2 activation in human bladder transitional carcinoma cells
Authors: Ou Ting‐Tsz , Wang Chau‐Jong , Lee Yung‐Shu , Wu Cheng‐Hsun , Lee Huei‐Jane 
Published: June 2010

AbstractScope: Cell cycle regulation is a critical issue in cancer treatment. Previously, gallic acid (GA) has been reported to possess anticancer ability. Here, we have evaluated the molecular mechanism of GA on cell cycle modulation in a human bladder transitional carcinoma cell line (TSGH‐8301 cell). Methods and results: Using flow cytometer analysis, exposure of the cells to 40 μM GA resulted in a statistically significant increase in G2/M phase cells, which was accompanied by a decrease in G0/G1 phase cells. GA‐treated cells resulted in significant growth inhibition in a dose‐dependent manner accompanied by a decrease in cyclin‐dependent kinases (Cdk1), Cyclin B1, and Cdc25C, but significant increases in p‐cdc2 (Tyr‐15) and Cip1/p21 by western blotting. Additional mechanistic studies showed that GA induces phosphorylation of Cdc25C at Ser‐216. This mechanism leads to its translocation from the nucleus to the cytoplasm resulting in an increased binding with 14‐3‐3β. When treated with GA, phosphorylated Cdc25C can be activated by ataxia telangiectasia‐mutated checkpoint kinase 2 (Chk2). This might be a DNA damage response as indicated by Ser‐139 phosphorylation of histine H2A.X. Furthermore, treatment of the cells with a Chk2 inhibitor significantly attenuated GA‐induced G2/M phase arrest. Conclusion: These results indicate that GA can induce cell cycle arrest at G2/M phase via Chk2‐mediated phosphorylation of Cdc25C in a bladder transitional carcinoma cell line.
Compressed sensing MRI with multichannel data using multicore processors
Authors: Chang Ching‐Hua , Ji Jim 
Published: June 2010

AbstractCompressed sensing (CS) is a promising method to speed up MRI. Because most clinical MRI scanners are equipped with multichannel receive systems, integrating CS with multichannel systems may not only shorten the scan time but also provide improved image quality. However, significant computation time is required to perform CS reconstruction, whose complexity is scaled by the number of channels. In this article, we propose a reconstruction procedure that uses ubiquitously available multicore central processing unit to accelerate CS reconstruction from multiple channel data. The experimental results show that the reconstruction efficiency benefits significantly from parallelizing the CS reconstructions and pipelining multichannel data into multicore processors. In our experiments, an additional speedup factor of 1.6–2.0 was achieved using the proposed method on a quad‐core central processing unit. The proposed method provides a straightforward way to accelerate CS reconstruction with multichannel data for parallel computation. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Application of k‐space energy spectrum analysis for inherent and dynamic B0 mapping and deblurring in spiral imaging
Authors: Truong Trong‐Kha , Chen Nan‐kuei , Song Allen W. 
Published: June 2010

AbstractSpiral imaging is vulnerable to spatial and temporal variations of the amplitude of the static magnetic field (B0) caused by susceptibility effects, eddy currents, chemical shifts, subject motion, physiological noise, and system instabilities, resulting in image blurring. Here, a novel off‐resonance correction method is proposed to address these issues. A k‐space energy spectrum analysis algorithm is first applied to inherently and dynamically generate a B0 map from the k‐space data at each time point, without requiring any additional data acquisition, pulse sequence modification, or phase unwrapping. A simulated phase evolution rewinding algorithm and an automatic residual deblurring algorithm are then used to correct for the blurring caused by both spatial and temporal B0 variations, resulting in a high spatial and temporal fidelity. This method is validated against conventional B0 mapping and deblurring methods, and its advantages for dynamic MRI applications are demonstrated in functional MRI studies. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Diffusion‐weighted spectroscopy: A novel approach to determine macromolecule resonances in short‐echo time 1H‐MRS
Authors: Kunz N. , Cudalbu C. , Mlynarik V. , Hüppi P. S. , Sizonenko S. V. , Gruetter R. 
Published: June 2010

AbstractQuantification of short‐echo time proton magnetic resonance spectroscopy results in >18 metabolite concentrations (neurochemical profile). Their quantification accuracy depends on the assessment of the contribution of macromolecule (MM) resonances, previously experimentally achieved by exploiting the several fold difference in T1. To minimize effects of heterogeneities in metabolites T1, the aim of the study was to assess MM signal contributions by combining inversion recovery (IR) and diffusion‐weighted proton spectroscopy at high‐magnetic field (14.1 T) and short echo time (=8 msec) in the rat brain. IR combined with diffusion weighting experiments (with δ/Δ = 1.5/200 msec and b‐value = 11.8 msec/μm2) showed that the metabolite nulled spectrum (inversion time = 740 msec) was affected by residuals attributed to creatine, inositol, taurine, choline, N‐acetylaspartate as well as glutamine and glutamate. While the metabolite residuals were significantly attenuated by 50%, the MM signals were almost not affected (<8%). The combination of metabolite‐nulled IR spectra with diffusion weighting allows a specific characterization of MM resonances with minimal metabolite signal contributions and is expected to lead to a more precise quantification of the neurochemical profile. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Clinical prostate T2 quantification using magnetization‐prepared spiral imaging
Authors: Foltz Warren D. , Chopra Supriya , Chung Peter , Bayley Andrew , Catton Charles , Jaffray David , Wright Graham A. , Haider Masoom A. , Ménard Cynthia 
Published: June 2010

AbstractT2 quantification may augment diagnostic T2‐weighted imaging; to improve cancer detection via auto‐segmentation of multi‐parametric acquisitions and to potentiate longitudinal studies of prostate cancer. However, robust quantitative techniques are not generally accessible or refined for clinical translation. This research describes the adaptation of a magnetization‐prepared spiral imaging technique, termed T2prep for prostate application, providing whole gland coverage within a 5‐min interval with considerable insensitivity to radio‐frequency (RF) inhomogeneities. Clinical piloting in two cohorts with distinct clinical histories demonstrated the anticipated differences in zonal and tumor T2, including tumor T2 shortening compared to peripheral zone, and post‐radiotherapy shortening of peripheral zone T2. SNR calculations were performed for data acquired with or without an endo‐rectal coil in tandem with a torso phased array, to judge the potential for voxel‐based T2 mapping and thereby support focal biological characterization of cancer, hypoxia, and response to therapy within regions of dense cancer burden. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
A robust methodology for in vivo T1 mapping
Authors: Barral Joëlle K. , Gudmundson Erik , Stikov Nikola , Etezadi‐Amoli Maryam , Stoica Petre , Nishimura Dwight G. 
Published: June 2010

AbstractIn this article, a robust methodology for in vivo T1 mapping is presented. The approach combines a gold standard scanning procedure with a novel fitting procedure. Fitting complex data to a five‐parameter model ensures accuracy and precision of the T1 estimation. A reduced‐dimension nonlinear least squares method is proposed. This method turns the complicated multi‐parameter minimization into a straightforward one‐dimensional search. As the range of possible T1 values is known, a global grid search can be used, ensuring that a global optimal solution is found. When only magnitude data are available, the algorithm is adapted to concurrently restore polarity. The performance of the new algorithm is demonstrated in simulations and phantom experiments. The new algorithm is as accurate and precise as the conventionally used Levenberg‐Marquardt algorithm but much faster. This gain in speed makes the use of the five‐parameter model viable. In addition, the new algorithm does not require initialization of the search parameters. Finally, the methodology is applied in vivo to conventional brain imaging and to skin imaging. T1 values are estimated for white matter and gray matter at 1.5 T and for dermis, hypodermis, and muscle at 1.5 T, 3 T, and 7 T. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.