237 research outputs found
Doubleāprobe measurement in recombining plasma using NAGDISāII
We have studied the validity of the double-probe method in recombining plasmas. Electron temperature (Te) measured with a double probe was quantitatively evaluated by taking into account the influences of plasma potential fluctuation, plasma resistivity, and electron density fluctuation on the currentāvoltage characteristics. Differential potential fluctuation and plasma resistivity between two electrodes have a minor effect on Te especially when the inter-distance is small (typically 1āmm). Scattering of measured Te due to the density fluctuation was sufficiently suppressed by making the data acquisition time long (typically 4 s) and taking the average. There is a good agreement between Te measured with the optimized double-probe method and that with laser Thomson scattering diagnostics
Molybdenum-99 (99Mo) Adsorption Profile of Zirconia-Based Materials for 99Mo/99mTc Generator Application
Technetium-99m (99mTc) plays a major role in diagnostic nuclear medicine and has not yet been replaced with any other radionuclides. It is available through the 99Mo/99mTc generator. The use of low-specific-activity 99Mo for 99Mo/99mTc generator application requires high adsorptive capacity sorbents. This study focused on the determination of 99Mo adsorption capacity of several zirconia materials, namely monoclinic nanozirconia, orthorhombic nanozirconia, sulfated zirconia,Ā Ā and phosphated zirconia. These materials were synthesized by using the sol-gel method and characterized using FT-IR spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM-EDS). The determination of 99Mo adsorption capacity of these materials was carried out by soaking the materials in a Na299MoO4 solution with pH of 3 and 7, at temperatures ranging from room temperature to 90 Ā°C, for 1 and 3 hours. The results indicated that monoclinic nanozirconia has a 99Mo adsorption capacity of 76.9 mg Mo/g, whereas orthorhombic nanozirconia, sulfated zirconia, and phosphatedĀ zirconia have 99Mo adsorption capacities of 150.1 mg Mo/g, 15.58 mg Mo/g, and 12.74 mg Mo/g, respectively. It appears that orthorhombic nanozirconia has the highest 99Mo adsorption capacity among the synthesized materials and can be applied as a candidate material for the 99Mo/99mTc generator
Quantitative assessment of inter-observer variability in target volume delineation on stereotactic radiotherapy treatment for pituitary adenoma and meningioma near optic tract
<p>Abstract</p> <p>Background</p> <p>To assess inter-observer variability in delineating target volume and organs at risk in benign tumor adjacent to optic tract as a quality assurance exercise.</p> <p>Methods</p> <p>We quantitatively analyzed 21 plans made by 11 clinicians in seven CyberKnife centers. The clinicians were provided with a raw data set (pituitary adenoma and meningioma) including clinical information, and were asked to delineate the lesions and create a treatment plan. Their contouring and plans (10 adenoma and 11 meningioma plans), were then compared. In addition, we estimated the influence of differences in contouring by superimposing the respective contours onto a default plan.</p> <p>Results</p> <p>The median planning target volume (PTV) and the ratio of the largest to the smallest contoured volume were 9.22 cm<sup>3 </sup>(range, 7.17 - 14.3 cm<sup>3</sup>) and 1.99 for pituitary adenoma, and 6.86 cm<sup>3 </sup>(range 6.05 - 14.6 cm<sup>3</sup>) and 2.41 for meningioma. PTV volume was 10.1 Ā± 1.74 cm<sup>3 </sup>for group 1 with a margin of 1 -2 mm around the CTV (n = 3) and 9.28 Ā± 1.8 cm<sup>3</sup>(p = 0.51) for group 2 with no margin (n = 7) in pituitary adenoma. In meningioma, group 1 showed larger PTV volume (10.1 Ā± 3.26 cm<sup>3</sup>) than group 2 (6.91 Ā± 0.7 cm<sup>3</sup>, p = 0.03). All submitted plan keep the irradiated dose to optic tract within the range of 50 Gy (equivalent total doses in 2 Gy fractionation). However, contours superimposed onto the dose distribution of the default plan indicated that an excessive dose 23.64 Gy (up to 268% of the default plan) in pituitary adenoma and 24.84 Gy (131% of the default plan) in meningioma to the optic nerve in the contours from different contouring.</p> <p>Conclusion</p> <p>Quality assurance revealed inter-observer variability in contour delineation and their influences on planning for pituitary adenoma and meningioma near optic tract.</p
The RIKEN integrated database of mammals
The RIKEN integrated database of mammals (http://scinets.org/db/mammal) is the official undertaking to integrate its mammalian databases produced from multiple large-scale programs that have been promoted by the institute. The database integrates not only RIKENās original databases, such as FANTOM, the ENU mutagenesis program, the RIKEN Cerebellar Development Transcriptome Database and the Bioresource Database, but also imported data from public databases, such as Ensembl, MGI and biomedical ontologies. Our integrated database has been implemented on the infrastructure of publication medium for databases, termed SciNetS/SciNeS, or the Scientistsā Networking System, where the data and metadata are structured as a semantic web and are downloadable in various standardized formats. The top-level ontology-based implementation of mammal-related data directly integrates the representative knowledge and individual data records in existing databases to ensure advanced cross-database searches and reduced unevenness of the data management operations. Through the development of this database, we propose a novel methodology for the development of standardized comprehensive management of heterogeneous data sets in multiple databases to improve the sustainability, accessibility, utility and publicity of the data of biomedical information
Mechanism and Enantioselectivity in Palladium-Catalyzed Conjugate Addition of Arylboronic Acids to Ī²āSubstituted Cyclic Enones: Insights from Computation and Experiment
Enantioselective conjugate additions of arylboronic acids to Ī²-substituted cyclic enones have been previously reported from our laboratories. Air- and moisture-tolerant conditions were achieved with a catalyst derived in situ from palladium(II) trifluoroacetate and the chiral ligand (S)-t-BuPyOx. We now report a combined experimental and computational investigation on the mechanism, the nature of the active catalyst, the origins of the enantioselectivity, and the stereoelectronic effects of the ligand and the substrates of this transformation. Enantioselectivity is controlled primarily by steric repulsions between the t-Bu group of the chiral ligand and the Ī±-methylene hydrogens of the enone substrate in the enantiodetermining carbopalladation step. Computations indicate that the reaction occurs via formation of a cationic arylpalladium(II) species, and subsequent carbopalladation of the enone olefin forms the key carbonācarbon bond. Studies of nonlinear effects and stoichiometric and catalytic reactions of isolated (PyOx)Pd(Ph)I complexes show that a monomeric arylpalladiumāligand complex is the active species in the selectivity-determining step. The addition of water and ammonium hexafluorophosphate synergistically increases the rate of the reaction, corroborating the hypothesis that a cationic palladium species is involved in the reaction pathway. These additives also allow the reaction to be performed at 40 Ā°C and facilitate an expanded substrate scope
Gateways to the FANTOM5 promoter level mammalian expression atlas
The FANTOM5 project investigates transcription initiation activities in more than 1,000 human and mouse primary cells, cell lines and tissues using CAGE. Based on manual curation of sample information and development of an ontology for sample classification, we assemble the resulting data into a centralized data resource (http://fantom.gsc.riken.jp/5/). This resource contains web-based tools and data-access points for the research community to search and extract data related to samples, genes, promoter activities, transcription factors and enhancers across the FANTOM5 atlas. Electronic supplementary material The online version of this article (doi:10.1186/s13059-014-0560-6) contains supplementary material, which is available to authorized users
Incidence of anterior disc displacement without reduction of the temporomandibular joint in patients with dentofacial deformity
The aim of this study was to investigate the incidence of anterior disc displacement without reduction (ADDwoR) of the temporomandibular joint (TMJ) in patients with dentofacial deformity. Eighty-eight female patients (176 joints) with skeletal class III malocclusion and 33 female patients (66 joints) with skeletal class II malocclusion, with or without anterior open bite and asymmetry, were evaluated. Magnetic resonance imaging (MRI) of the TMJ was used to diagnose ADDwoR. A statistical analysis was performed to examine the relationship between ADDwoR and skeletal structure. ADDwoR was present in 37 of the 66 joints (56.1%) in class II compared to 34 of the 176 joints (19.3%) in class III (P < 0.05). In class III, ADDwoR was significantly more common in joints with mandibular asymmetry (24/74; 32.4%) than in joints with open bite (9/62; 14.5%) and joints with open bite and without mandibular asymmetry (1/38; 2.6%). In class II, ADDwoR was significantly less common in joints with mandibular asymmetry and without open bite (1/8; 12.5%). ADDwoR was only observed on the deviated side in both class III and class II with mandibular asymmetry. The prevalence of ADDwoR differed according to the dentofacial morphology
Cationic Pd(II)-catalyzed CāH activation/cross-coupling reactions at room temperature: synthetic and mechanistic studies
Cationic palladium(II) complexes have been found to be highly reactive towards aromatic CāH activation of arylureas at room temperature. A commercially available catalyst [Pd(MeCN)4](BF4)2 or a nitrile-free cationic palladium(II) complex generated in situ from the reaction of Pd(OAc)2 and HBF4, effectively catalyzes CāH activation/cross-coupling reactions between aryl iodides, arylboronic acids and acrylates under milder conditions than those previously reported. The nature of the directing group was found to be critical for achieving room temperature conditions, with the urea moiety the most effective in promoting facile coupling reactions at an ortho CāH position. This methodology has been utilized in a streamlined and efficient synthesis of boscalid, an agent produced on the kiloton scale annually and used to control a range of plant pathogens in broadacre and horticultural crops. Mechanistic investigations led to a proposed catalytic cycle involving three steps: (1) CāH activation to generate a cationic palladacycle; (2) reaction of the cationic palladacycle with an aryl iodide, arylboronic acid or acrylate, and (3) regeneration of the active cationic palladium catalyst. The reaction between a cationic palladium(II) complex and arylurea allowed the formation and isolation of the corresponding palladacycle intermediate, characterized by X-ray analysis. Roles of various additives in the stepwise process have also been studied
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