Results 1 - 10 of 385
Results 1 - 10 of 385. Search took: 0.019 seconds
|Sort by: date | relevance|
[en] A method for the simulation determination of inorganic As(III) and As(V) is described, which involves arsine generation, measurement of the molecular absorption of arsine in the gas phase at 190 nm and quantification od As(III) and As(V) based on different heights and areas of absorbance versus time profiles of arsine generated from both inorganic species. The limits of detection were 0.5 μg of As(III) and 3 μg of As(V) in a sample volume of 1 ml. An interference study for both species was made and the method was applied to the determination of As2O3 and As2O5 in a standard glass sample. (author). 29 refs.; 3 figs.; 5 tabs
[en] Purpose: To evaluate the pattern of failure after limited margin radiotherapy for glioblastoma. Methods and Materials: We analyzed 62 consecutive patients with newly diagnosed glioblastoma treated between 2006 and 2008 with standard fractionation to a total dose of 60Gy with concurrent temozolomide (97%) or arsenic trioxide (3%). The initial clinical target volume included postoperative T2 abnormality with a median margin of 0.7cm. The boost clinical target volume included residual T1-enhancing tumor and resection cavity with a median margin of 0.5cm. Planning target volumes added a 0.3- or 0.5-cm margin to clinical target volumes. The total boost planning target volume (PTVboost) margin was 1cm or less in 92% of patients. The volume of recurrent tumor (new T1 enhancement) was categorized by the percent within the 60-Gy isodose line as central (>95%), infield (81-95%), marginal (20-80%), or distant (<20%). For comparison, an initial planning target volume with a 2-cm margin and PTVboost with a 2.5-cm margin were created for each patient. Results: With a median follow-up of 12 months, radiographic tumor progression developed in 43 of 62 patients. Imaging was available for analysis in 41: 38 (93%) had central or infield failure, 2 (5%) had marginal failure, and 1 (2%) had distant failure relative to the 60-Gy isodose line. The treated PTVboost (median, 140cm3) was, on average, 70% less than the PTVboost with a 2.5-cm margin (median, 477cm3) (p < 0.001). Conclusions: A PTVboost margin of 1cm or less did not appear to increase the risk of marginal and/or distant tumor failures compared with other published series. With careful radiation planning and delivery, it appears that treatment margins for glioblastoma can be reduced.
[en] Arsenic trioxide (As2O3) can be used as a possible pharmaceutical alternative that augments radiofrequency (RF) ablation by reducing tumor blood flow. The aim of this study was to assess the effect of intraarterial and intravenous administration of As2O3 on RF-induced ablation in an experimentally induced liver tumor. VX2 carcinoma was grown in the livers of 30 rabbits. As2O3 (1 mg/kg) was administered through the hepatic artery (n = 10, group A) or ear vein (n = 10, group B), 30 minutes before RF ablation (125 mA ± 35; 90 ± 5 degrees Celsius). As a control group, 10 rabbits were treated with RF ablation alone (group C). RF was intentionally applied to the peripheral margin of the tumor so that ablation can cover the tumor and adjacent hepatic parenchyma. Ablation areas of the tumor and adjacent parenchymal changes among three groups were compared by the Kruskal-Wallis and Mann-Whitney U test. The overall ablation areas were 156 ± 28.9 mm2 (group A), 119 ± 31.7 (group B), and 92 ± 17.4 (group C, p < 0.04). The ablation area of the tumor was significantly larger in group A (73 ± 19.7 mm2) than both group B (50 ± 19.4, p = 0.02) and group C (28 ± 2.2, p < 0.01). The ratios of the tumoral ablation area to the overall ablation area were larger in group A (47 ± 10.5%) than that of the other groups (42 ± 7.3% in group B and 32 ± 5.6% in group C) (p < 0.03). Radiofrequency-induced ablation area can be increased with intraarterial or intravenous administration of As2O3. The intraarterial administration of As2O3 seems to be helpful for the selective ablation of the tumor.
[en] Granulates are produced from As2S3, As2O5, alloys of selenic/tellurium, or compound systems based on chalcogenides. For this purpose the original substance consisting of As and Se is filled as loose material into the reactor of an equipment that has got an electric heating and a mixer-settler for homogenizing the melting phase of the mixture. In this way a product is formed meeting the requirements for a photoconductor compound to be evaporated in high-vacuum. (DG)
[de]Es wird ein Granulat aus As2S3, As2O5, Selen-Tellur-Legierungen oder Mehrstoffsysteme auf Chalkogenidbasis hergestellt. Das Ausgangsgemisch aus As und Se wird hierzu als Schuettgut in ein Reaktionsgefaess einer Apparatur gebracht, die eine elektrische Heizung und einen Ruehrer zum Homogenisieren der Schmelzphase des Gemisches aufweist. Es entsteht ein Produkt, das den Anforderungen genuegt, die an eine unter Hochvakuum verdampfbare Photoleiter-Verbindung gestellt werden. (DG)
[en] The Indian crested porcupine, Hystrix indica, is widely distributed in the irrigated forests of Punjab, Pakistan and causes serious damage to trees, nursery stocking, field crops and vegetables. Field trials were conducted to determine the efficacy of aluminium phosphide (Phostoxin, 3g tablets) and arsenic trioxide bait (at 2.5g per apple) against the porcupine in a forest plantation. For fumigation with phostoxin, tablets were used at the rate of four, five, six and seven tablets per den. Observations showed that four tablets were ineffective, five and six tablets provided partial control, while seven tablets provided complete control of porcupines. Baiting with arsenic trioxide also resulted in 89 % reduction of the porcupine population occupying the treated dens. (author)
[en] Residues of neoasozine in rice grain were determined by neutron activation and colorimetric techniques. Twice application of the chemical before flowering did not lead to any increased residue level while 4-times application resulted in significant increase in the residue level up to 0.54 - 0.75 mg As2O3/kg. The partition ratio of arsenic residues into polished rice grain and bran was 73 : 27 in 100 % polishing while most of the residues in the bran was transferred to oil cake fraction during solvent extraction, reaching up to 2.9 mg As2O3/kg. The neutron activation technique was advantageous because of its high sensitivity and the smaller sample amounts required for analysis. (author)
[en] I. The chemistry of the bipentaborane 2,2'-(B5H8)2 is investigated to some extent. Pyrolysis of 2,2'-(B5H8)2 resulted in the formation of non-volatile solid boron hydrides and hydrogen. Treatment of 2,2'-(B5H8)2 with bromine in the presence of AlBr3 resulted in the isolation of 1,1'Br2-2,2'-(B5H7)2. Reaction of 2,2'-(B5H8)2 with deprotonating agents resulted in the formation of the corresponding anions. Reaction of 2,2'-(B5H8)2 with diborane followed by acidification afforded n-B9H15 and B10H14 in moderate yield. II. Reaction of K+B9H12S- with potassium polyselenide resulted in the isolation of stable white crystals of B9H9SSe. Treatment of B9H9SSe with one equivalent of base in methanol gave the unstable heteroborane B8H9(OCH3)SSE and treatment with two equivalents of base afforded yellow crystals of B7H9SSe. Reaction of K+B9H12S- with arsenic trioxide in aqueous basic solution gave the electron-rich heteroborane, B8H8As2S in moderate yield. This resulted in the isolation and identification of Et3N.BH3 and the new metalloborane B7H7As2SCo(C5H5). Treatment of B10H11Se- with As2O3 resulted in the isolation of the stable nido-heteroborane B8H8As2Se in low yield. Reaction of B7C2H13 with potassium polyselenide gave the arachno selenacarborane B7H2C11Se in low yield. The structure of the new heteroborane is proposed on the basis of 11B and 1H nmr spectra. Reaction of B7C2H13 with AsCl3 resulted in the isolation of white stable crystals of B7C2H9As2 in 40 percent yield
[en] A series of glasses excavated in the Albanian city of Lezha (ancient Lissos) were analyzed by the combined PIXE-PIGE method in air and by source-excited XRF. The analysis revealed two types of glass that can be identified as facon de Venise glass and its subsequent younger phase, produced by chemically purer components and using As2O3 as decolorant.