bluuebunny/crossref_metadata_2025 huggingface dataset:
Three-Dimensional Flow Patterns in the Upper Human Airways
Authors: Bauer Katrin , Rudert Alexander , Brücker Christoph
Published: June 2012

Flow dynamics are studied for different ventilation conditions at a three-dimensional model of the human lung airways. The model is based on Horsfield and Weibel data and bifurcates down to the sixth generation. The flow is analyzed numerically and compared to experimental data received from exactly the same model. Numerical and experimental results agree well. Based on this agreement, flow behavior for conventional mechanical ventilation (CMV) as well as for high frequency oscillatory ventilation (HFOV) conditions can be analyzed. Velocity profiles as well as secondary flow structures are investigated during different phases of the unsteady flow. It is shown that the velocity profiles at peak inspiration and expiration are very similar for CMV and HFOV, probably due to too short branch lengths for the development of a frequency-dependent velocity profile. At the flow reversal times, characteristic zones of bidirectional mass flow emerge with increasing amplitude at higher frequencies. Furthermore, secondary flow structures are analyzed. This investigation reveals that the structures only depend on the local curvature and branch orientation, but are not influenced much by the nearby upper or lower branching generations.
SU‐E‐I‐51: Investigation of Absorbed Dose to the Skin, Eyes and Thyroid of Patients during CT Angiography and Comparison with Conventional Angiography
Authors: Tavakoli H. M , Jabari K , Salman J
Published: June 2012

Purpose: Imaging is one of the most important methods to diagnose cardiovascular and especially coronary artery diseases. The advent of multislice CT in recent years has made new capabilities for medical imaging. Coronary CT angiography as a new imaging method is performed with these devices. Despite of many advantages with it, patients absorbed dose is relatively high in coronary ct angiography, Then study on various aspects of absorbed dose to patients seems to be necessary. The aim of this study was to evaluate absorbed dose to patient's skin, thyroid and eye during coronary CT angiography and to compare it with the same organ doses in conventional angiography. Methods: A number of 67 patients referring to Isfahan's Azzahra(s) and Sina hospitals for coronary CT angiography imaging were investigated to evaluate absorbed dose to their skin, thyroid and eyes. Organs absorbed dose was obtained via measurement by TLD. One pair GR‐200 type TLDs were used for each organ dose measurement. TLDS were calibrated using Co 60 source before measuring. Absorbed dose to each organ considered to be as average of TLDs readout. Coronary CT angiography was performed either by 64 rows detectors CT lighspeed VCT in Azzahra(s) or Philips model in Sina hospitals. Results: The average of absorbed dose to skin, thyroid and eye during coronary CT angiography was 8.32± 1.73, 2.06± 1.68 and 0.3± 0.16 cGy, respectively. Absorbed dose to the same organs during conventional coronary angiography was 6.64± 9.30, 0.15± 0.17 and 0.03± 0.03 cGy, respectively. There is a significant differences in adsorbed dose to these organs between coronary CT angiography and conventional angiography(p<0.001).absorbed dose to skin ranges between 5.15–12.22 cGy for CT angiography and between 0.07–39 cGy in conventional angiography. Conclusions: Absorbed dose to skin is higher than two other organs(thyroid and eye) due to direct irradiation. There is a significant variation in absorbed dose to skin for both CT and conventional angiography and it is greater for conventional angiography. Absorbed dose to organs is higher for CT angiography rather than conventional angiography. Radiation absorbed dose depends on various imaging selected parameters such as kVp and mAs, then, technicians play an important role on it. To decrease adsorbed dose to patients as low as possible they must be educated very well and implement what have learned in practice.
SU‐E‐T‐96: Energy Dependence of the New GafChromic‐ EBT3 Film's Dose Response‐Curve
Authors: Chiu‐Tsao S , Massillon‐JL G , Domingo‐Muñoz I , Chan M
Published: June 2012

Purpose: To study and compare the dose response curves of the new GafChromic EBT3 film for megavoltage and kilovoltage x‐ray beams, with different spatial resolution. Methods: Two sets of EBT3 films (lot#A101711‐02) were exposed to each x‐ray beam (6MV, 15MV and 50kV) at 8 dose values (50–3200cGy). The megavoltage beams were calibrated per AAPM TG‐51 protocol while the kilovoltage beam was calibrated following the TG‐61 using an ionization chamber calibrated at NIST. Each film piece was scanned three consecutive times in the center of Epson 10000XL flatbed scanner in transmission mode, landscape orientation, 48‐bit color at two separate spatial resolutions of 75 and 300 dpi. The data were analyzed using ImageJ and, for each scanned image, a region of interest (ROI) of 2×2cm2 at the field center was selected to obtain the mean pixel value with its standard deviation in the ROI. For each energy, dose value and spatial resolution, the average netOD and its associated uncertainty were determined. The Student's t‐test was performed to evaluate the statistical differences between the netOD/dose values of the three energy modalities, with different color channels and spatial resolutions. Results: The dose response curves for the three energy modalities were compared in three color channels with 75 and 300dpi. Weak energy dependence was found. For doses above 100cGy, no statistical differences were observed between 6 and 15MV beams, regardless of spatial resolution. However, statistical differences were observed between 50kV and the megavoltage beams. The degree of energy dependence (from MV to 50kV) was found to be function of color channel, dose level and spatial resolution. Conclusions: The dose response curves for GafChromic EBT3 films were found to be weakly dependent on the energy of the photon beams from 6MV to 50kV. The degree of energy dependence varies with color channel, dose and spatial resolution. GafChromic EBT3 films were supplied by Ashland Corp. This work was partially supported by DGAPA‐UNAM grant IN102610 and Conacyt Mexico grant 127409
SU‐E‐T‐258: Assessment of Radiation Induced Second Cancer Risks in Proton Therapy and IMRT for Organs inside the Main Radiation Field
Authors: Paganetti H , Moteabbed M , Athar B , Adams J , Schneider U , Yock T
Published: June 2012

Purpose: Radiation therapy can potentially cause a second malignancy. There is clinical evidence that those occur typically within the beam path in the medium/high dose region. The purpose of this study was to assess the risk for developing a radiation induced tumor within the treated volume and to compare this risk for proton therapy and IMRT. Methods: Fully contoured age and gender specific whole body phantoms (4‐year and 14‐year old) were uploaded into a treatment planning system and typical tumor volumes were contoured based on patients treated for optic glioma and vertebral body Ewing's sarcoma. Lifetime attributable risks (LARs) for developing a second malignancy were calculated using a risk model incorporating factors for cell kill, mutations, repopulation, and inhomogeneous organ doses. Results: For standard fractionation schemes, the LAR for developing a second malignancy from radiation therapy alone were found to be up to 2.7% for a 4‐year old optic glioma patient treated with IMRT considering a soft tissue carcinoma risk model only. Sarcoma risks were found to be below 1% in all cases. For the 14‐year old, risks were found to be about a factor of 2 lower. For the Ewing's sarcoma cases the risks based on the sarcoma model were typically higher than the carcinoma risks, i.e. up to 1.3% LAR for soft tissue sarcoma. Generally, the risk from proton therapy turned out to be lower by a factor of 2 to 10. However, comparison of a 3‐field and 4‐field proton plan shows that the distribution of the dose, i.e., the particular treatment plan, plays a role as well. Conclusions: In general, proton therapy can significantly reduce the risk for developing an in‐field second malignancy. Risk analysis based on our formalism could be applied within treatment planning programs to guide treatment plans for pediatric patients. Federal Share of program income earned by Massachusetts General Hospital on NIH/NCI C06 CA059267
TH‐A‐BRB‐01: The Radiobiology of Small Fraction Numbers
Authors: Brenner David J
Published: June 2012

There is much interest in reducing fraction numbers in radiotherapy, both in the context of single‐fraction radiosurgery, and also for hypofractionation ‐ for example for prostate, lung and breast. We will discuss what radiobiology can tell us about the use and optimization of these new approaches in radiotherapy.From 1900 to the 1920s radiotherapeutic practice was dominated by the German Erlangen school, which advocated the use of a single large “castrating” dose, as well as pioneering the “crossfire” technique to spare normal tissue ‐ the two keystones of modern stereotactic radiotherapy. By the 1930s, the classic studies of Regaud and Coutard resulted in widespread use of larger fraction numbers, and this has remained the state of the art in most radiotherapeutic settings. We will review the key biological factors that determine radiotherapeutic response, and discuss their application to single‐fraction radiosurgery ‐ for malignant tumors, for benign tumors, and for vascular lesions. We conclude that, unless the target lesion is very large, vascular lesions and benign tumors can be well treated with a single dose fraction. For malignant tumors, however, fractionated radiotherapy should always result in a better outcome than a single fraction, particular from the perspective of inactivating hypoxic tumor cells, present in almost all tumors. Hypofractionation, typically using 5 to 10 rather than 30 to 35 fractions, is becoming increasingly popular for treating some malignant tumors. In the context of the same radiobiology discussed earlier, we will discuss the rationale for hypofractionation for prostate, for breast, and for lung. We conclude that there is a strong biological rationale for hypofractionation of prostate cancer, relating to the paucity of dividing cells in most prostate tumors, which makes them respond to changes in fractionation very much like surrounding normal tissue. In other sites, one might expect hypofractionation to be a possible option for malignancies which are a) low grade, and b) small, and in a parallel‐type organ. Hypofractionation of small, low‐grade lung / breast tumors meet some of these criteria, and may well be at least non‐inferior to more conventional fractionation regimes.

Learning Objectives:

1. Understand the radiobiological principles underlying responses to changes in fractionation

2. Understand their application to single‐fraction radiosurgery

3. Understand their application to hypofractionation
TH‐C‐BRA‐07: Quantitative Cone‐Beam CT Imaging in Radiation Therapy Using Planning CT as a Prior: First Patient Studies
Authors: Niu T , Al‐Basheer A , Zhu L
Published: June 2012

Purpose: Quantitative cone‐beam CT (CBCT) imaging is on increasing demand for high‐performance image guided radiation therapy (IGRT). However, the current CBCT has poor image qualities mainly due to scatter contamination. To improve CBCT imaging for quantitative use, we recently proposed a correction method using planning CT (pCT) as the prior knowledge. Though showing promising phantom results, our method needs more clinical validations especially when patients have large organ deformations. In this abstract, we extend our method from bench to bedside by including several new components. Methods: Our algorithm estimates the primary signals of CBCT projections via forward projection on the pCT image, and then obtains the low‐frequency errors in CBCT raw projections by subtracting the estimated primaries and low‐pass filtering. We improve the algorithm by using deformable registration to minimize the geometry difference between the pCT and the CBCT images. Since the registration performance relies on the accuracy of the CBCT image, we design an optional iterative scheme to update the CBCT image in the registration. Large correction errors result from the mismatched objects in the pCT and the CBCT scans. Another optional step of gas pocket and couch matching is applied to reduce these effects. Results: The proposed method is evaluated on four prostate patients. Using the pCT image as the ground truth, the overall mean CT number error is reduced from over 300 to below 16 HU in the selected ROIs, and the spatial non‐uniformity error is suppressed from over 18% to below 2%. The average soft‐tissue contrast is improved by an average factor of 2.6. Conclusions: We further improve our pCT‐based CBCT correction algorithm for clinical use. Superior correction performance has been demonstrated on four patient studies. By providing quantitative CBCT images, our approach significantly increases the accuracy of advanced CBCT‐based clinical applications for IGRT. the NIH under the grant number 1R21EB012700‐01A1
Synthesis and Structure of a Terminal Uranium Nitride Complex
Authors: King David M. , Tuna Floriana , McInnes Eric J. L. , McMaster Jonathan , Lewis William , Blake Alexander J. , Liddle Stephen T.
Published: June 2012

UN Coordination

Uranium is best known for its radioactivity. From the standpoint of lower-energy chemistry, uranium is also intriguing for its bonding motifs, which involve trinodal f orbitals.

King
et al.

(p.
717
, published online 28 June; see the Perspective by

Sattelberger and Johnson

) synthesized and isolated a molecule bearing a uranium-nitrogen triple bond. Theoretical calculations allowed the mapping of the orbital interactions, distinguishing it from similar motifs in compounds of lighter metals. The preparation required use of a rigid, bulky ligand framework to keep the reactive uranium nitride group from binding to another molecule nearby, a pathway that has plagued prior attempts to prepare this class of compounds.
Complete Genome Sequence of an H7N3 Avian Influenza Virus Isolated from Ducks in Southern China
Authors: Jiao Peirong , Wei Liangmeng , Yuan Runyu , Song Yafen , Cao Lan , Liao Ming
Published: June 2012

We report here the complete genomic sequence of an H7N3 avian influenza virus (AIV) isolate, which was obtained from duck in 1996. This is the first report of this subtype of AIV being isolated from duck in Guangdong of Southern China. Genomic sequence and phylogenetic analyses showed that it was highly homologous with the wild bird virus A/ruddy turnstone/Delaware Bay/135/1996 (H7N3) and that all eight genes of this virus belonged to the North America gene pool. The availability of genome sequences is helpful to further investigations of epidemiology and evolution of AIV between waterfowl and wild birds.
Bivalve-enhanced nitrogen removal from coastal estuaries
Authors: Carmichael Ruth H. , Walton William , Clark Heidi
Published: June 2012

Interest in use of bivalves to remediate estuarine eutrophication has increased in recent years. High variation among data sets, substantial focus on particle removal, and insufficient links to anthropogenic nitrogen (N) sources encouraged this empirical examination of N removal by bivalves from estuaries receiving different N loads. We determined the capacity of the oyster Crassostrea virginica to remove N by comparing N assimilated into tissues with anthropogenic N from land or available in phytoplankton. Oyster growth yielded 0.2–0.4 g N in tissues and depended on estuary-specific conditions. δ15N values confirmed that N in oyster tissues derived from local anthropogenic sources. At representative restoration and aquaculture conditions (≤400 oysters·m–2at 0.5%–1.0% of estuary area), estimated N removal was ≤15% of land-derived loads and <1% of phytoplankton N. N removal via biogeochemical processes was negligible during grow-out, but became important after oysters attained harvestable size. This study explicitly demonstrates that oysters assimilated land-derived N, but suggests that bivalve bioremediation consider trade-offs between intensity of planting, ecological effects, and available space.
Diversity of nematomorph and cohabiting nematode parasites in riparian ecosystems around the Kii Peninsula, Japan
Authors: Sato Takuya , Watanabe Katsutoshi , Tamotsu Satoshi , Ichikawa Akihiko , Schmidt-Rhaesa Andreas
Published: June 2012

Nematomorph parasites manipulate terrestrial invertebrate hosts to seek out and enter streams, thereby deriving substantial energy subsidies to stream salmonids. Despite this potential ecological role of nematomorphs, knowledge of their diversity remains unclear. Using molecular (i.e., 18S rRNA and mitochondrial COI genes) and morphological approaches, we explored the species diversity of suspected nematomorph specimens, as well as their terrestrial orthopteran hosts, in 10 stream and riparian ecosystems around the Kii Peninsula, central Honshu, Japan. We distinguished seven species of nematomorphs belonging to three genera based on molecular and morphological data. The identifications by the two approaches were consistent with each other at the genus level but partly not at the species level. Furthermore, among the suspected nematomorph specimens, eight nematode species belonging to the orders Mermithida and Trichocephalida were found from two sites. Several orthopterans, mainly camel crickets, were infected by nematomorphs and by a nematode without obvious species specificity. These results suggest that diverse parasites and their orthopteran hosts drive the parasite-mediated energy flow across the stream and riparian ecosystems.
Agricultural land use alters trophic status and population density of deer mice (Peromyscus maniculatus) on the North American Great Plains
Authors: White A.J. , Poulin R.G. , Wissel B. , Doucette J.L. , Somers C.M.
Published: June 2012

Habitat conversion is among the most important causes of environmental change worldwide, yet relatively little is known about its potential influence on trophic interactions. We investigated the effects of agricultural land use on carbon and nitrogen stable isotope values, trophic status, population density, and body condition of deer mice ( Peromyscus maniculatus (Wagner, 1845)) in a grassland ecosystem. Muscle δ15N (cropland = 7.6‰ ± 1.3‰; hay fields = 7.9‰ ± 1.3‰; native prairie = 7.2‰ ± 2.1‰) from deer mice did not vary with land use despite baseline soil and vegetation δ15N differences. Enrichment of deer mice over vegetation (Δδ15N) was, on average, a full trophic level (~2.5‰) higher on native prairie (6.4‰ ± 1.6‰) than on cropland (3.9‰ ± 2.3‰), and intermediate in hay fields (5.9‰ ± 2.0‰). Relative density of deer mice was more than twofold higher in crop and hay fields compared with native prairie, but body condition did not vary with land use. Our results suggest that agricultural activity caused a shift in the trophic level and relative abundance of a generalist grassland omnivore. Soil and vegetation δ15N reflected anthropogenic N inputs to agricultural fields but were not useful as general markers of habitat use in this study.
PREDICTION OF EFFECTIVE PERMEABILITY IN POROUS MEDIA BASED ON SPONTANEOUS IMBIBITION EFFECT
Authors: CAI JIANCHAO , YOU LIJUN , HU XIANGYUN , WANG JING , PENG RONGHUA
Published: June 2012

Permeability is an important parameter for characterizing the transport properties (e.g. heat and mass transfer) of porous media. It is one of the crucial issues that the permeability of porous media is exactly and quickly decided in many fields such as reservoir engineering, groundwater engineering and composite material modeling. Spontaneous imbibition is a fundamental and ubiquitous natural phenomenon extensively existing in a variety of processes. In this paper, the relationships between the height and weight of imbibition versus the time are derived based on Darcy's law, and a simple method for predicting effective permeability of porous media using spontaneous imbibition effect is proposed, including expressions for permeabilities of artificial and natural porous media. The validity of the proposed models is analysed and tested by experimental data.
TOP QUARK PHYSICS AT THE LHC: A REVIEW OF THE FIRST TWO YEARS
Authors: SCHILLING FRANK-PETER
Published: June 2012

This review summarizes the highlights in the area of top quark physics obtained with the two general purpose detectors ATLAS and CMS during the first two years of operation of the Large Hadron Collider (LHC). It covers the 2010 and 2011 data taking periods, where the LHC provided pp collisions at a center-of-mass energy of [Formula: see text]. Measurements are presented of the total and differential top quark pair production cross-section in many different channels, the top quark mass and various other properties of the top quark and its interactions, for instance the charge asymmetry. Measurements of single top quark production and various searches for new physics involving top quarks are also discussed. The already very precise experimental data are in good agreement with the standard model (SM).
FOUR-DIMENSIONAL MANIFOLDS CONSTRUCTED BY LENS SPACE SURGERIES ALONG TORUS KNOTS
Authors: TANGE MOTOO , YAMADA YUICHI
Published: June 2012

A framed knot with an integral coefficient determines a simply-connected 4-manifold by 2-handle attachment. Its boundary is a 3-manifold obtained by Dehn surgery along the framed knot. For a pair of such Dehn surgeries along distinct knots whose results are homeomorphic, it is a natural problem: Determine the closed 4-manifold obtained by pasting the 4-manifolds along their boundaries. We determine the complete list (set) of pairs of integral surgeries along distinct torus knots whose resulting manifolds are orientation preserving/reversing homeomorphic lens spaces, and study the closed 4-manifolds constructed as above. The list consists of five sequences. All framed links and Kirby calculus are indexed by integers. As a bi-product, some sequences of embeddings of lens spaces into the standard 4-manifolds are constructed.
THE POSSIBILITY OF INFLATION IN ASYMPTOTICALLY SAFE GRAVITY
Authors: HONG SUNGWOOK E. , LEE YOUNG JAE , ZOE HEESEUNG
Published: June 2012

We examine the inflationary modes in the cubic curvature theories in the context of asymptotically safe gravity. On the phase space of the Hubble parameter, there exists a critical point which corresponds to the slow-roll inflation in Einstein frame. Most of the e-foldings are attained around the critical point for each inflationary trajectories. If the coupling constants gi have the parametric relations generated as the power of the relative energy scale of inflation H0 to the cutoff Λ, a successful inflation with more than 60 e-foldings occurs near the critical point.
A BERESTYCKI–LIONS THEOREM REVISITED
Authors: ZHANG JIANJUN , ZOU WENMING
Published: June 2012

In 1983, Berestycki and Lions [Nonlinear scalar field equations I. Existence of a ground state, Arch. Ration. Mech. Anal.82 (1983) 313–346] studied the following elliptic problem: [Formula: see text] where N ≥ 3, g is subcritical at infinity. They proved the existence of a ground state under some appropriate growth restrictions on g. In the present paper, we improve this result by showing that under the critical growth assumption on g the problem admits a ground state. In addition we study a mountain pass characterization of the least energy solutions of the problem. Without the assumption of the monotonicity of the function [Formula: see text], we show that the mountain pass value gives the least energy level.
CHARACTERIZATION OF NANO-HYDROXYAPATITE SYNTHESIZED FROM SEA SHELLS THROUGH WET CHEMICAL METHOD
Authors: SANTHOSH S. , PRABU S. BALASIVANANDHA
Published: June 2012

Nano-hydroxyapatite (HA) was synthesized by a wet chemical reaction using powdered sea shells ( CaO ) as starting material which was converted to calcium hydroxide ( Ca(OH) 2) and subsequently reacted with phosphoric acid (H3PO4) . Initially raw sea shells ( CaCO3 ) were thermally converted to amorphous calcium oxide by heat treatment. Two sets of experiments were done; in the first experiment, HA powder was dried in an electric furnace and in the second experiment, the reactants were irradiated in a domestic microwave oven followed by microwave drying. In each set of experiments, the concentrations of the reactants were decreased gradually. HA was synthesized by slow addition of phosphoric acid (H3PO4) in to calcium hydroxide ( Ca(OH) 2) maintaining the pH of the solution at 10 to avoid the formation of calcium deficient apatites. In both the experiments, Ca:P ratio of 1.67 was maintained for the reagents. The synthesized samples showed X-ray diffraction (XRD) patterns corresponding to hydroxyapatite. The wet chemical process with furnace drying resulted in HA particles of size 7–34 nm, whereas microwave irradiated process yielded HA particles of size 34–102 nm as evidenced from XRD analyses. The above experimental work done by wet chemical synthesis to produce HA powder from sea shells is a simple processing method at room temperature. Microwave irradiation leads to uniform crystallite sizes as evident from this study, at differing concentrations of the reactants and is a comparatively easy method to synthesize HA. The high resolution scanning electron microscopy (HRSEM)/transmission electron microscopic (TEM) analyses revealed the characteristic rod-shaped nanoparticles of HA for the present study.
GRADED POISSON STRUCTURES AND SCHOUTEN–NIJENHUIS BRACKET ON ALMOST COMMUTATIVE ALGEBRAS
Authors: NGAKEU FERDINAND
Published: June 2012

We introduce and study the notion of abelian groups graded Schouten–Nijenhuis bracket on almost commutative algebras and show that any Poisson bracket on such algebras is defined by a graded bivector as in the classical Poisson manifolds. As a particular example, we introduce and study symplectic structures on almost commutative algebras. Our result is a generalization of the ℤ2-graded (super)-Poisson structures.
NATURAL CONNECTION WITH TOTALLY SKEW-SYMMETRIC TORSION ON ALMOST CONTACT MANIFOLDS WITH B-METRIC
Authors: MANEV MANCHO
Published: June 2012

A natural connection with totally skew-symmetric torsion on almost contact manifolds with B-metric is constructed. The class of these manifolds, where the considered connection exists, is determined. Some curvature properties for this connection, when the corresponding curvature tensor has the properties of the curvature tensor for the Levi-Civita connection and the torsion tensor is parallel, are obtained.
Kinetic studies on the self-aggregation of a non ionic porphyrin in the presence and absence of ionic liquid by molecular dynamics simulation
Authors: Ghadamghahi Maryam , Ajloo Davood , Moalem Mahmood
Published: June 2012

Aggregation kinetics of a porphyrin derivative in the absence and presence of different concentrations, below and above the critical micelle concentration (CMC) of three ionic liquids (ILs); 1-octyl-3-methylimidazolium, 1-dodecyl-3- methyl imidazolium and 1-octadecyl-3-methylimidazolium chloride was studied using molecular dynamics simulation. Effect of IL, with different chain lengths on the aggregation of a porphyrin derivative, 5,10,15,20-tetrakis(2,5-dihydroxyphenyl)porphyrin, was investigated. The low amount of each ionic liquid (below CMC) observed to favors the formation of aggregates; further increasing ionic liquid concentration leads to the destabilization of aggregates. The compared calculated rate constants also support these results. Aggregation of imidazolium ILs proved to take place with longer alkyl chains that favors aggregation.
Oxidative stress effects of fullerene-porphyrin derivatives in photodynamic therapy
Authors: Ion Rodica Mariana , Daicoviciu Doina , Filip Adriana Gabriela , Clichici Simona , Muresan Adriana
Published: June 2012

Due to their special and growing medical recent interest, the fullerenes started to be a very studied class of chemical compounds. In order to improve their water solubility and to reduce their cytotoxic characteristics, the fullerenes have been coupled in a system fullerene/PVP/porphyrin (C60/PVP/TPP) and its application in photodynamic therapy will be evaluated in this paper. The oxidative stress effects on photodynamic therapy with systems fullerene/poly-N-vinylpirrolidone/5,10,15,20-tetrakis(4-phenyl)porphyrin (C60/PVP/TPP) were tested on Wistar rats sub-cutaneously inoculated with Walker 256 carcinoma. The animals were irradiated with red light (λ = 685 nm; D = 50 J/cm2; 15 minutes) 24 h after intra-peritoneal administration of 10 mg/kg body weight of the system C60/PVP/TPP. After photodynamic therapy, the free radicals in tumors have been indirectly evaluated by lipid peroxides level (measured as thiobarbituric reactive substances) and protein carbonyls (indices of oxidative effects produced on susceptible biomolecules), both of them increasing in tumor tissues of animals 24 h after treatment. The levels of thiol groups and total antioxidant capacity have been determined in tumors, too, their decreasing values being the effect of the strong tumoral oxidative process.
SUPPRESSION OF SIDELOBES IN SINGLE-PHOTON 4PI CONFOCAL MICROSCOPY BY FÖRSTER RESONANT ENERGY TRANSFER
Authors: CHEN JIANFANG , CHENG YA
Published: June 2012

Recently, we theoretically demonstrate that utilization of silica nanobeads co-doped with Cy3 and Cy5 molecules instead of single dye molecules as fluorescent labels can enable optical resolutions far beyond the diffraction-limit. Here, we show that by combining the 4Pi microscopy and the novel fluorescent label, it is possible to completely suppress the sidelobes in 4Pi focal spot and significantly enhance the optical resolution in the axial direction.
USING A HEAT PUMP AS AN ALTERNATIVE TO SUPPORT SOLAR COLLECTOR FOR WATER HEATING IN BRAZIL
Authors: DE MELO REIS ROBERTS VINICIUS , OLIVEIRA RAPHAEL NUNES , MACHADO LUIZ , KOURY RICARDO NICOLAU NASSAR
Published: June 2012

With related greenhouse effect environmental issues linked to the constant problems of the fluctuations in oil prices, the use of solar energy is an important renewable energy source. Brazil is a country which is privileged considering the high rates of solar irradiation present throughout almost the entire national territory. Nevertheless, during certain times of the year, there is a solar energy deficit, which leads solar systems to require electrical resistance support at these times. The use of electrical resistance represents 23.5% of electric energy consumption and it presents a low residential energy efficiency. The purpose of this work is an alternative technical design for reduction of electric energy consumption through the use of a solar energy system together with a generating heat pump for water heaters for households, as well as the financial feasibility study on the use of this system. One such heat pump has been designed, constructed and tested experimentally. The average performance coefficient is equal to 2.10, a low value due to the use of a hermetic reciprocating compressor. Despite this low moderate price coefficient of acquisition and installation of a heat pump, one can allow a return on investment in from 2.1 to 3.3 years, whereas the equipment has a useful life of about 20 years, this period of return on investment is interesting.
Rapid Decomposition of Cellulose Dissolved in Ionic Liquid Using Gas–Liquid Interface Discharge
Authors: Furukawa Shoichiro , Inoue Nobuhiro , Ishioka Toshio , Furuya Kenji , Harata Akira
Published: June 2012

Cellulose was dissolved at 3 wt % in 15 mL of 1-allyl-3-methylimidazolium chloride ([Amim]Cl) together with 2 wt % water, and then gas–liquid interface discharge was carried out at 20 W for 200 s. As a result, 7.6% of initially dissolved cellulose decomposed and 3.9% of initially dissolved cellulose changed into reducing sugar. Adding a small amount of water to the solution was essential for the decomposition of cellulose. [Amim]Cl was stable against the discharge, as determined from the NMR signals measured before and after the discharge.
Phase-Shifted Fresnel Zone Lenses for Photomixing Generation of Coherent THz Wave
Authors: Vijayakumar Anand , Uemukai Masahiro , Suhara Toshiaki
Published: June 2012

Novel optics configurations simplified by using phase-shifted Fresnel zone lenses (FZLs) are proposed for THz wave generation by mixing optical beams from integrated twin lasers on GaAs photomixers. The phase-shifted FZL superimposes and collinearly collimates the beams from the closely-aligned twin lasers, or superimposes and focuses them directly onto a photomixer, with a high efficiency. Phase-shifted binary and analog FZLs were designed and fabricated by electron beam writing. Good performances close to the theoretical prediction were obtained, and THz wave generation was successfully demonstrated.
Fabrication of TiN/Ge Contact with Extremely Low Electron Barrier Height
Authors: Yamamoto Keisuke , Harada Kenji , Yang Haigui , Wang Dong , Nakashima Hiroshi
Published: June 2012

We succeeded in improving a TiN/Ge contact by optimizing the TiN deposition. From contact resistance measurements of TiN/n+-Ge, the specific contact resistivity was determined to be 7.9×10-6 Ω·cm2 for a surface impurity concentration of 3.9×1019 cm-3, suggesting that an interlayer between TiN and Ge is conductive. It was also found that a peripheral surface-state current dominated the reverse leakage current of the contact. The leakage current was significantly decreased by the surface passivation using GeO2. The passivated TiN/p-Ge contact showed a high hole barrier height of 0.57 eV, implying an extremely low electron barrier height of 0.09 eV.
Optical Properties of Crescent Pair for Sensing
Authors: Wang Yufei , Fu Feiya , Jiang Bin , Qi Aiyi , Xue Qikun , Zheng Wanhua
Published: June 2012

By the out-of-particle surface plasmon (SP) excitation, we theoretically investigate optical properties of the crescent pair in the near infrared region. These properties used for refractive index sensing are studied under the coherent control of SP waves excited by the detecting light and the controlling light. Only through tuning the phase of the controlling light, the extracted signal is intensified, and the sensing controllability can be achieved. The crescent pair realizes the separation of different function areas, and makes the detectable area broadened for the probe. Simulation results demonstrate the new sensing scheme proposed may be applied in future nanocrescent sensing.
Analysis of Charge Compensation Mechanisms in Pr1-xAxCoO3-δ (A = Ca, Sr) by X-ray Absorption Near-Edge Structure
Authors: Yoshioka Tsuyoshi , Yamamoto Tomoyuki , Kitada Akihiko
Published: June 2012

The charge compensation mechanisms in polycrystalline Pr1-x
Ca
x
CoO3-δ and Pr1-x
Sr
x
CoO3-δ here synthesized by the solid-state reaction method have been investigated by analyzing the Pr-L3 and Co-K X-ray absorption near-edge structure (XANES) with the aid of first-principles calculations. The valence states of Pr ions in these materials were determined to be trivalent (Pr3+) and independent of the concentration of alkaline-earth ions observed in the Pr-L3 XANES profile. The Co-K XANES spectra shifted to the higher-energy side with an increase in alkaline-earth concentration and were examined in detail by first-principles calculations. Using calculated XANES results, we successfully determined that the valence state of Co ions is an intermediate value between 3+ and 4+ and increases with an increase in the concentration of alkaline-earth ions in Pr1-x
A
x
CoO3-δ (A = Ca, Sr) accompanying oxygen vacancy.
Morphological Study on Porous Silicon Carbide Membrane Fabricated by Double-Step Electrochemical Etching
Authors: Omiya Takuma , Tanaka Akira , Shimomura Masaru
Published: June 2012

The structure of porous silicon carbide membranes that peeled off spontaneously during electrochemical etching was studied. They were fabricated from n-type 6H SiC(0001) wafers by a double-step electrochemical etching process in a hydrofluoric electrolyte. Nanoporous membranes were obtained after double-step etching with current densities of 10–20 and 60–100 mA/cm2 in the first and second steps, respectively. Microporous membranes were also fabricated after double-step etching with current densities of 100 and 200 mA/cm2. It was found that the pore diameter is influenced by the etching current in step 1, and that a higher current is required in step 2 when the current in step 1 is increased. During the etching processes in steps 1 and 2, vertical nanopore and lateral crack formations proceed, respectively. The influx pathway of hydrofluoric solution, expansion of generated gases, and transfer limitation of positive holes to the pore surface are the key factors in the peeling-off mechanism of the membrane.
Hydrogen Effects on the Properties of Silicon/Nitrogen-Coincorporated Diamond-Like Carbon Films Prepared by Plasma-Enhanced Chemical Vapor Deposition
Authors: Nakazawa Hideki , Okuno Saori , Miura Soushi , Kamata Ryosuke
Published: June 2012

We have deposited silicon/nitrogen-coincorporated diamond-like carbon (Si–N–DLC) films by radio-frequency plasma-enhanced chemical vapor deposition using hexamethyldisilazane (HMDS) as the Si and N source, and investigated the structure, chemical bonding, and the mechanical and tribological properties of the films. We compared the properties between Si–N–DLC films deposited with hydrogen gas and those with argon gas, which were used as the dilution gases. As HMDS flow ratio [HMDS/(HMDS+CH4)] increased, internal stress decreased and, at the same time, adhesion strength determined by scratch tests increased. However, many particles were observed on the film surfaces when the deposition with argon gas was carried out. It was found that the use of hydrogen gas was effective in suppressing the formation of particles and further increasing adhesion strength. Friction coefficient, as evaluated by ball-on-plate reciprocating friction tests, decreased with increasing HMDS flow ratio. The friction coefficient values of the Si–N–DLC films were as low as those of Si-incorporated DLC films. We also found that employing hydrogen gas reduced the friction coefficient and wear rate of the films.
Dry Etching of Lead-Free (K,Na)NbO3 Piezoelectric Films by Ar/C4F8 Plasma
Authors: Horikiri Fumimasa , Shibata Kenji , Suenaga Kazufumi , Watanabe Kazutoshi , Nomoto Akira , Mishima Tomoyoshi , Kurokawa Fumiya , Kanno Isaku
Published: June 2012

We investigated the dry-etching characteristics of lead-free (K,Na)NbO3 (KNN) thin films by inductively coupled plasma-reactive ion etching (ICP-RIE) using Ar/C4F8 as the reactive gas mixture. The KNN etching depth showed a linear relationship as a function of the etching time with a few minutes' delay at the beginning. The etching rate increased with increasing antenna power and bias power. The antenna and bias dependences of the etching rate showed good linearity. The KNN/Pt selectivity increased with increasing antenna power and decreasing bias power. Thus, a high KNN/Pt selectivity was obtained under conditions of a high antenna power and a low bias power. The maximum KNN/Pt selectivity was 86. These etching results enable device fabrication using KNN thin films.
Plasma-Induced Damage and Recovery on Au/n-GaN Schottky Diode in Different Processes
Authors: Lee ChangYong , Sekiguchi Hiroto , Okada Hiroshi , Wakahara Akihiro
Published: June 2012

The effects of plasma-induced damage on deep traps in n-GaN have been investigated using current–voltage (I–V), capacitance–voltage (C–V), and photocapacitance (PHCAP) measurements. The Au/n-GaN Schottky barrier diodes were fabricated in an inductively coupled plasma ion etching (ICP-RIE) system. After mesa etching to achieve ohmic contact, the n-GaN surface, at which Schottky contacts are fabricated, is etched ∼100 nm by ICP-RIE with various Cl2/Ar ratios and RIE bias powers (P
B), to introduce plasma damage. The electrical properties of the fabricated Shottky barrier diodes (SBDs) strongly dependent on the RIE gas composition and the bias power P
B applied to the sample stage. In order to overcome the residue and plasma damage on the Schottky area, the samples were treated with HCl at 110 °C for 30 min. Several deep levels (1.8, 2.5, and 3.0 eV below the conduction band) were detected by PHCAP measurement. Improved electrical characteristics were achieved as a result of the HCl treatment and sintering process. The PHCAP measurement results also revealed the effectiveness of thermal and chemical treatments.
Mechanisms and roles of muscarinic activation in guinea-pig adrenal medullary cells
Authors: Inoue Masumi , Harada Keita , Matsuoka Hidetada , Nakamura Jun , Warashina Akira
Published: June 2012

Muscarinic receptors are expressed in the adrenal medullary (AM) cells of various mammals, but their physiological roles are controversial. Therefore, the ionic mechanism for muscarinic receptor-mediated depolarization and the role of muscarinic receptors in neuronal transmission were investigated in dissociated guinea-pig AM cells and in the perfused guinea-pig adrenal gland. Bath application of muscarine induced an inward current at −60 mV. This inward current was partially suppressed by quinine with an IC50 of 6.1 μM. The quinine-insensitive component of muscarine-induced currents changed the polarity at −78 mV and was inhibited by bupivacaine, a TWIK-related acid-sensitive K+ (TASK) channel inhibitor. Conversely, the current-voltage relationship for the bupivacaine-insensitive component of muscarine currents showed a reversal potential of −5 mV and a negative slope below −40 mV. External application of La3+ had a double action on muscarine currents of both enhancement and suppression. Immunoblotting and immunocytochemistry revealed expression of TASK1 channels and cononical transient receptor potential channels 1, 4, 5, and 7 in guinea-pig AM cells. Retrograde application of atropine reversibly suppressed transsynaptically evoked catecholamine secretion from the adrenal gland. The results indicate that muscarinic receptor stimulation in guinea-pig AM cells induces depolarization through inhibition of TASK channels and activation of nonselective cation channels and that muscarinic receptors are involved in neuronal transmission from the splanchnic nerve.
Early metabolic changes measured by 1H MRS in healthy and dystrophic muscle after injury
Authors: Xu Su , Pratt Stephen J. P. , Spangenburg Espen E. , Lovering Richard M.
Published: June 2012

Skeletal muscle injury is often assessed by clinical findings (history, pain, tenderness, strength loss), by imaging, or by invasive techniques. The purpose of this work was to determine if in vivo proton magnetic resonance spectroscopy (1H MRS) could reveal metabolic changes in murine skeletal muscle after contraction-induced injury. We compared findings in the tibialis anterior muscle from both healthy wild-type (WT) muscles (C57BL/10 mice) and dystrophic ( mdx mice) muscles (an animal model for human Duchenne muscular dystrophy) before and after contraction-induced injury. A mild in vivo eccentric injury protocol was used due to the high susceptibility of mdx muscles to injury. As expected, mdx mice sustained a greater loss of force (81%) after injury compared with WT (42%). In the uninjured muscles, choline (Cho) levels were 47% lower in the mdx muscles compared with WT muscles. In mdx mice, taurine levels decreased 17%, and Cho levels increased 25% in injured muscles compared with uninjured mdx muscles. Intramyocellular lipids and total muscle lipid levels increased significantly after injury but only in WT. The increase in lipid was confirmed using a permeable lipophilic fluorescence dye. In summary, loss of torque after injury was associated with alterations in muscle metabolite levels that may contribute to the overall injury response in mdx mice. These results show that it is possible to obtain meaningful in vivo 1H MRS regarding skeletal muscle injury.
Data-driven functional clustering reveals dominance of face, place, and body selectivity in the ventral visual pathway
Authors: Vul Edward , Lashkari Danial , Hsieh Po-Jang , Golland Polina , Kanwisher Nancy
Published: June 2012

Regions selective for faces, places, and bodies feature prominently in the literature on the human ventral visual pathway. Are selectivities for these categories in fact the most robust response profiles in this pathway, or is their prominence an artifact of biased sampling of the hypothesis space in prior work? Here we use a data-driven structure discovery method that avoids the assumptions built into most prior work by 1) giving equal consideration to all possible response profiles over the conditions tested, 2) relaxing implicit anatomical constraints (that important functional profiles should manifest themselves in spatially contiguous voxels arising in similar locations across subjects), and 3) testing for dominant response profiles over images, rather than categories, thus enabling us to discover, rather than presume, the categories respected by the brain. Even with these assumptions relaxed, face, place, and body selectivity emerge as dominant in the ventral stream.
Selectivity for grip type and action goal in macaque inferior parietal and ventral premotor grasping neurons
Authors: Bonini Luca , Ugolotti Serventi Francesca , Bruni Stefania , Maranesi Monica , Bimbi Marco , Simone Luciano , Rozzi Stefano , Ferrari Pier Francesco , Fogassi Leonardo
Published: June 2012

Grasping objects requires the selection of specific grip postures in relation to the objects' physical properties. Furthermore, grasping acts can be embedded in actions aimed at different goals, depending on the context in which the action is performed. Here we assessed whether information on grip and action type integrate at the single-neuron level within the parieto-frontal motor system. For this purpose, we trained three monkeys to perform simple grasp-to-eat and grasp-to-place actions, depending on contextual cues, in which different grip types were required in relation to target features. We recorded 173 grasping neurons: 86 from the inferior parietal area PFG and 87 from the ventral premotor area F5. Results showed that most neurons in both areas are selective for grip type, but the discharge of many of them, particularly in PFG, appears to differ in relation to action context. Kinematics data and control experiments indicated that neuronal selectivity appears more likely to depend on the action goal triggered by the context than on specific contextual elements. The temporal dynamics of grip and goal selectivity showed that grasping neurons reflect first “how” the object has to be grasped (grip), to guide and monitor the hand shaping phase, and then “why” the action is performed (goal), very likely to facilitate subsequent motor acts following grasping. These findings suggest that, in the parieto-frontal system, grip types and action goals are processed by both parallel and converging pathways, and area PFG appears to be particularly relevant for integrating this information for action organization.
Endothelial Cells and Astrocytes: AConcerto en Duoin Ischemic Pathophysiology
Authors: Berezowski Vincent , Fukuda Andrew M. , Cecchelli Roméo , Badaut Jérôme
Published: June 2012

The neurovascular/gliovascular unit has recently gained increased attention in cerebral ischemic research, especially regarding the cellular and molecular changes that occur in astrocytes and endothelial cells. In this paper we summarize the recent knowledge of these changes in association with edema formation, interactions with the basal lamina, and blood-brain barrier dysfunctions. We also review the involvement of astrocytes and endothelial cells with recombinant tissue plasminogen activator, which is the only FDA-approved thrombolytic drug after stroke. However, it has a narrow therapeutic time window and serious clinical side effects. Lastly, we provide alternative therapeutic targets for future ischemia drug developments such as peroxisome proliferator- activated receptors and inhibitors of the c-Jun N-terminal kinase pathway. Targeting the neurovascular unit to protect the blood-brain barrier instead of a classical neuron-centric approach in the development of neuroprotective drugs may result in improved clinical outcomes after stroke.