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Dose Rate (dose + rate)
Selected AbstractsRadiolysis of Confined Water: Hydrogen Production at a High Dose RateCHEMPHYSCHEM, Issue 12 2005Sophie Le Caër Dr. Abstract The production of molecular hydrogen in the radiolysis of dried or hydrated nanoporous controlled-pore glasses (CPG) has been carefully studied using 10 MeV electron irraditation at high dose rate. In all cases, the H2 yield increases when the pore size decreases. Moreover, the yields measured in dried materials are two orders of magnitude smaller than those obtained in hydrated glasses. This proves that the part of the H2 coming from the surface of the material is negligible in the hydrated case. Thus, the measured yields correspond to those of nanoconfined water. Moreover, these yields are not modified by the presence of potassium bromide, which is a hydroxyl radical scavenger. This experimental observation shows that the back reaction between H2 and HO. does not take place in such confined environments. These porous materials have been characterized before and after irradiation by means of Fourier-transform infrared (FT-IR) spectroscopy, electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) techniques, which helps to understand the elementary processes taking place in this type of environment, especially the protective effect of water on the surface in the case of hydrated glasses. [source] Direct luminescence chronology of the Epipaleolithic Kebaran site of Nahal Hadera V, IsraelGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 4 2003D.I. Godfrey-Smith We report direct luminescence ages for the culture-bearing sediments of the Kebaran site of Nahal Hadera V (NHV) in the coastal plain of Israel. Although the site contains, in addition to rich lithic deposits, plentiful mammalian bone, it has proved to be undatable using radiocarbon dating, in spite of the fact that the cultural context places the time of occupation well within the range of radiocarbon dating. In contrast, luminescence dating of the site sediments proved successful. Luminescence ages were determined using the single aliquot additive-dose (SAA) method, applied to sand-sized quartz extracts to determine past equivalent doses (De). Dose rates (R) were calculated using thick source alpha counting for the uranium (U) and thorium (Th) concentrations and x-ray fluorescence analysis for the potassium (K20) concentration. Of the five samples collected at the site, four represent cultural and subcultural deposits and the fifth represents the geological substrate for the archaeological deposit, a quartz-rich, carbonate-cemented dune sand known as aeolianite or kurkar. The luminescence age of the kurkar is 42.7 ± 6.3 ka. Human occupation of the site occurred between 21.3 ka and 14.0 ka ago, during the Last Glacial Maximum. © 2003 Wiley Periodicals, Inc. [source] Studies of thioguanine-resistant lymphocytes induced by in vivo irradiation of miceENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 5 2008Irene M. Jones Abstract The frequency of Hprt -deficient lymphocytes in mice after in vivo , irradiation, has been found to vary as a function of time elapsed after exposure and irradiation dose. The frequency of mutant lymphocytes in spleen was determined using an in vitro, clonogenic assay for thioguanine-resistant T-lymphocytes. Mice were exposed to single doses of 0,400 cGy from cesium-137 or to eight daily doses of 50 cGy. The time to maximum-induced mutant frequency was 3 weeks. The dose response was strikingly curvilinear at 3,5 weeks after irradiation, but less precisely defined for 10,53 weeks after exposure, being fit by either linear or quadratic dependence. Three weeks after eight daily 50 cGy exposures, mutant frequency was elevated above controls and mice exposed to 50 cGy (which were not distinct from the nonirradiated controls), but only 17% in that of mice given a single 400 cGy fraction. This fractionation effect and the curvilinearity of the early dose,response curve suggested that saturation of repair increased the yield of mutations at higher acute doses. The decline of spleen mutant frequency in mice observed between 5 and 10 weeks after irradiation may reflect selection against some mutants. The marked variation of mutant frequency, as a function of time after irradiation and of dose rate, emphasize the need to evaluate these variables carefully and consistently in future studies. Environ. Mol. Mutagen., 2008. © 2008 Wiley-Liss, Inc. [source] ESR isochron dating analyses at Bau de l'Aubesier, Provence, France: Clues to U uptake in fossil teethGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 7 2001Bonnie A.B. Blackwell At Bau de l'Aubesier, Provence, Mousterian artifacts and human teeth occur in inhomogeneous ("lumpy") sedimentary deposits that include bone and tooth fragments and extensive burnt horizons. Electron spin resonance (ESR) isochron analyses of mammal teeth, which use multiple subsamples with different U concentrations, can measure the external dose rate experienced by the tooth regardless of reworking and sedimentary dose rate changes. Isochron analyses do depend on the U uptake model assumed, but can also identify teeth that have experienced secondary U uptake or leaching. Using 11 teeth from six archaeological layers, the isochrons demonstrate that at least three teeth have experienced secondary uptake. For eight teeth, the U uptake has apparently not followed strictly early (EU), linear (LU), or recent uptake (RU), but more closely approximates LU-RU. Comparing volumetrically averaged sedimentary geochemistry with thermoluminescent dosimetry suggests that fossil tissues in the sediment have also experienced LU-RU uptake. LU-RU uptake can explain standard ESR ages that underestimate the true fossil age. © 2001 John Wiley & Sons, Inc. [source] Postoperative brachytherapy alone and combined postoperative radiotherapy and brachytherapy boost for squamous cell carcinoma of the oral cavity, with positive or close margins,HEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 3 2004Michel Lapeyre MD Abstract Background. Postoperative radiotherapy is necessary for squamous cell carcinoma (SCC) of the oral cavity with positive or close margins. The aim of the study is to define the indications of postoperative brachytherapy (BRT). Methods. From 1979 to 1993, 82 patients with positive or close margins had postoperative BRT (58 T1,2, 24 T3,4, 45 mobile tongue, 37 floor of mouth). Forty-six patients had combined radiotherapy (RT) with a mean dose of 48 Gy, and BRT boost with a mean dose of 24 Gy. Thirty-six patients had BRT alone with a mean dose of 60 Gy. BRT was performed with interstitial low dose rate Iridium 192. Results. Overall survival (OS), cause-specific survival (CSS), and local control (LC) at 5 years were, respectively, for T1,2/N0N, with BRT, 75%, 85%, and 88%,and with RT-BRT 70%, 92%, and 92%; for T1,2/N+ with RT-BRT, 44%, 67%, and 78%; for T3,4/N, with RT-BRT, 42%, 90%, and 80%; and for T3,4/N+ with RT-BRT, 22%, 43%, and 57%. Prognostic factors for OS, CSS, and LC were N+ (p , .009), extracapsular spread (ECS+;p , .000001), and T stage for LC only (p = .02). Prognostic factors for complications were a high number of wires with a cutoff at five wires (p = .008), a high dose rate with a cutoff at 0.57 Gy/hr (p = .01), and a high total dose (BRT + RT) with a cutoff at 71 Gy (p = .07). Conclusions. BRT alone for SCC T1,2/N0N, is better than RT-BRT because, with equivalent results, it avoids the adverse events of postoperative RT (xerostomia) and permits the treatment of a second head and neck primary in nonirradiated tissue. The results for the T3,4/N, are acceptable with this approach (ie, RT-BRT) but may be improved for N+. © 2004 Wiley Periodicals, Inc. Head Neck26: 216,223, 2004 [source] Simultaneous radiation grafting of vinylbenzyl chloride onto poly(tetrafluoroethylene- co -hexafluoropropylene) filmsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2009Junhwa Shin Abstract In this study, we demonstrated that vinylbenzyl chloride (VBC), a versatile monomer with reactive a chloromethyl group could be grafted onto a poly(tetrafluoroethylene- co -hexafluoropropylene) (FEP) film without a degradation of the chloromethyl group during a simultaneous irradiation process. The effects of various irradiation conditions such as the total dose, dose rate, solvent, and VBC concentration on the degree of grafting of VBC onto a FEP film were also investigated. The prepared PVBC-grafted films were characterized using FTIR, TGA, and SEM EDX. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Comparative evaluation of heating ability and biocompatibility of different ferrite-based magnetic fluids for hyperthermia applicationJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2007Pallab Pradhan Abstract In this study, lauric acid-coated, superparamagnetic, nanoparticle-based magnetic fluids of different ferrites (Fe3O4, MnFe2O4, and CoFe2O4) were prepared and compared in terms of heating ability and biocompatibility to evaluate the feasibility of use in hyperthermia treatment of cancer. All the magnetic fluids prepared had particles of average sizes 9,11 nm. Heating ability of these magnetic fluids was evaluated by calorimetric measurement of specific absorption rate (SAR) at 300 kHz frequency and 15 kA/m field. Fe3O4 and MnFe2O4 showed higher SAR (120 and 97 W/g of ferrite, respectively) than CoFe2O4 (37 W/g of ferrite). In vitro study on BHK 21 cell lines showed dose-dependent cell viability for all the magnetic fluids. Threshold-biocompatible ferrite concentration for all the magnetic fluids was 0.1 mg/mL. Above 0.2 mg/mL, CoFe2O4 was more toxic than the other magnetic fluids. On intravenous injection of different doses (50, 200, and 400 mg/kg body weight) of magnetic fluids in mice, no significant changes in hematological and biochemical parameters were observed for Fe3O4 and MnFe2O4. With CoFe2O4, an increase in SGPT levels at a dose rate of 400 mg/kg body weight was observed, indicating its mild hepatotoxic effect. However, histology of different vital organs showed no pathological changes for all the three magnetic fluids. Further, long term in vivo evaluation of biocompatibility of the lauric acid-coated ferrites is warranted. This study shows that lauric acid-coated, superparamagnetic Fe3O4 and MnFe2O4 may be used for hyperthermia treatment and are to be preferred over CoFe2O4. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] Effect of Calcium Propionate and Water Activity on Growth and Aflatoxins Production by,Aspergillus flavusJOURNAL OF FOOD SCIENCE, Issue 2 2010Sahib Alam ABSTRACT:, The efficacy of calcium propionate at 2 different doses (0.5% and 1%) against growth and aflatoxins production by,Aspergillus flavus,(A-2092) was investigated,in vitro,on Czapek yeast extract agar at different levels of water activity (aw) in the range of 0.94 to 0.996aw.,A. flavus,spores germinated on all calcium propionate and aw,treatments; however, 1% calcium propionate at 0.94 aw,delayed the germination process for up to 10 d. The growing rate of mycelia was slower (0.28 mm/d) at 1% calcium propionate and 0.94 aw. Aflatoxins (B1, B2, G1, and G2) were also produced minimally (36.1, 1, 1.86, and 1.01 ng/g of media, respectively) at the aforementioned dose rate of calcium propionate and water activity. It was concluded that addition of calcium propionate and aw,amelioration can prove effective tools for suppressing the germination, growth rate, and aflatoxins production by,A. flavus,in substrate. [source] Spectroscopic study of the penetration depth of grafted polystyrene onto poly(tetrafluoroethylene- co -perfluoropropylvinylether) substrates.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2002Abstract This study concerns the radiation grafting of styrene onto poly(tetrafluoroethylene- co -perfluoropropylvinylether) (PFA) substrates and the penetration depth of the graft. Grafting was obtained by the simultaneous irradiation method, and the spectroscopic analysis was made with the micro-Raman technique. Effects of grafting conditions such as the type of solvent, dose rate, and irradiation dose on the grafting yield were investigated. Of the different solvents used, the most efficient in terms of increasing grafting yield were dichloromethane, benzene, and methanol, respectively. A mixture of methanol and dichloromethane used as a solvent for styrene achieved a higher degree of grafting and concentration of grafted polystyrene onto the surface of PFA substrates than solutions of the monomer in the separate solvents. The degree of grafting increased with increasing radiation dose up to 500 kGy, stabilizing above this dose. However, the grafting yield decreased with an increase in the dose rate. The increase in the overall grafting yield was accompanied by a proportional increase in the penetration depth of the grafts into the substrate. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3191,3199, 2002 [source] Pharmacokinetics of cimetidine in dogs after oral administration of cimetidine tabletsJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 3 2009G. LE TRAON Long-term oral treatment with cimetidine is recommended to reduce vomiting in dogs with chronic gastritis. Despite this, few studies have specifically examined the plasma disposition and pharmacokinetics of cimetidine in dogs, particularly following repeated oral administration. The pharmacokinetics of cimetidine following oral administration as tablets was investigated in healthy dogs. Cimetidine was absorbed rapidly post-treatment (tmax = 0.5 h). A mean absolute bioavailability of 75% was calculated following a single oral administration of 5 mg cimetidine/kg body weight. After intravenous administration, a plasma half-life of 1.6 h was calculated. Repeated oral administration at the recommended dose rate and regime (5 mg/kg body weight three times daily) for 30 consecutive days did not lead to any accumulation of cimetidine in plasma. Food intake concomitant with oral administration of cimetidine delayed (tmax = 2.25 h) and decreased the rate and extent of absorption (AUC) by about 40%. Cimetidine was well absorbed in fasted dogs. Administration of food decreased the bioavailability of cimetidine by 40%. Cimetidine does not accumulate over time in plasma when administered long term to dogs. [source] Characterization of the pharmacokinetic disposition of levofloxacin in stallions after intravenous and intramuscular administrationJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2008A. GOUDAH The target of the present study was to investigate the plasma disposition kinetics of levofloxacin in stallions (n = 6) following a single intravenous (i.v.) bolus or intramuscular (i.m.) injection at a dose rate of 4 mg/kg bwt, using a two-phase crossover design with 15 days as an interval period. Plasma samples were collected at appropriate times during a 48-h administration interval, and were analyzed using a microbiological assay method. The plasma levofloxacin disposition was best fitted to a two-compartment open model after i.v. dosing. The half-lives of distribution and elimination were 0.21 ± 0.13 and 2.58 ± 0.51 h, respectively. The volume of distribution at steady-state was 0.81 ± 0.26 L/kg, the total body clearance (Cltot) was 0.21 ± 0.18 L/h/kg, and the areas under the concentration,time curves (AUCs) were 18.79 ± 4.57 ,g.h/mL. Following i.m. administration, the mean t1/2el and AUC values were 2.94 ± 0.78 h and 17.21 ± 4.36 ,g.h/mL. The bioavailability was high (91.76% ± 12.68%), with a peak plasma mean concentration (Cmax) of 2.85 ± 0.89 ,g/mL attained at 1.56 ± 0.71 h (Tmax). The in vitro protein binding percentage was 27.84%. Calculation of efficacy predictors showed that levofloxacin might have a good therapeutic profile against Gram-negative and Gram-positive bacteria, with an MIC , 0.1 ,g/mL. [source] Pharmacokinetics of total thyroxine in dogs after administration of an oral solution of levothyroxine sodiumJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 2 2008G. LE TRAON Oral l -thyroxine (l -T4) supplementation is used to replace thyroid hormone concentrations in dogs with hypothyroidism. The pharmacokinetics of l -T4 following administration of a solution (Leventa®) was investigated in healthy dogs. l -T4 was absorbed fairly rapidly (tmax 3 h). A mean bioavailability of 22% was calculated following a single oral administration of 40 ,g l -T4/kg body weight. Repeated oral administration at the same dose for 14 consecutive days did not lead to any accumulation of T4 in serum. After intravenous administration of l -T4, a serum half-life of 11.6 h was calculated. Food intake concomitant with l -T4 oral administration delayed l -T4 absorption and decreased its rate and extent by about 45%. The relative bioavailability of l -T4 following administration of a tablet formulation was about 50% of that of the l -T4 solution. The pharmacokinetic properties of liquid l -T4 after oral administration support the use of a dose rate of 20 ,g/kg once daily, as a starting dose for replacement therapy in dogs with hypothyroidism. [source] UNINTENTIONAL OVERDOSE WITH INTRATHECAL ZICONOTIDEPAIN MEDICINE, Issue 2 2002Article first published online: 4 JUL 200 Steven G. Charapata MD, Research Medical Center, Kansas City, MO; David Ellis MD, PhD, Elan Pharmaceuticals, South San Francisco, CA Ziconotide is a novel, N-type, voltage-sensitive calcium channel (VSCC) blocker, with well-documented efficacy as an intrathecal (IT) analgesic. Ziconotide has been administered to over 1000 chronic pain patients in nine clinical trials. Over 350 patients have been on ziconotide IT therapy for more than three months in a long-term safety and tolerability study. Common adverse events for ziconotide include dizziness, nausea, nystagmus, abnormal gait, constipation, urinary retention, somnolence, postural hypotension, vomiting, confusion and abnormal vision. Ziconotide adverse events are recognizable, reversible and manageable, by dose adjustment and slow dose titration. Case reports of unintentional overdose in six chronic pain patients treated with IT ziconotide are presented. These unintentional overdoses were attributable to pump programming or dilution errors; none were lethal. The patient who received the highest overdose was administered 31 mcg/hr over 24 hours, or nearly 750 mcg ziconotide, total. This hourly dose rate is 300-fold the current recommended initial dose rate of 0.1 mcg/hr. This patient was sedated, but arousable; vital signs were stable and patient had no change in blood pressure. His symptoms resolved within 24 hours. His Visual Analog Score of Pain Intensity (VASPI) was reduced from 82 at baseline to 2.5 at the end of the titration period. The patient elected to continue in the long-term IT ziconotide study. The other 5 cases of inadvertent overdose were less severe, with dose rate at 5 mcg/hr or less. Associated adverse events also resolved within 24-hours of discontinuing ziconotide infusion. Unlike an unintentional overdose with IT morphine, which slows respiration and could potentially lead to hypoxia, coma or death; ziconotide does not produce respiratory depression. No tolerance to the analgesic effect of ziconotide, or withdrawal symptoms after discontinuation of the drug have been reported. Ziconotide has a wide margin of safety as an IT analgesic. [source] Photoreactivation in Paramecium tetraurelia under Conditions of Various Degrees of Ozone Layer Depletion,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2005Akihisa Takahashi ABSTRACT Photoreactivation (PR) is an efficient survival mechanism that helps protect cells against the harmful effects of solar-ultraviolet (UV) radiation. The PR mechanism involves photolyase, just one enzyme, and can repair DNA damage, such as cyclobutane-pyrimidine dimers (CPD) induced by near-UV/blue light, a component of sunlight. Although the balance of near-UV/blue light and far-UV light reaching the Earth's surface could be altered by the atmospheric ozone layer's depletion, experiments simulating this environmental change and its possible effects on life have not yet been performed. To quantify the strength of UVB in sunlight reaching the Earth's surface, we measured the number of CPD generated in plasmid DNA after UVB irradiation or exposure to sunlight. To simulate the increase of solar-UV radiation resulting from the ozone layer depletion, Paramecium tetraurelia was exposed to UVB and/or sunlight in clear summer weather. PR recovery after exposure to sunlight was complete at a low dose rate of 0.2 J/m2·s, but was less efficient when the dose rate was increased by a factor of 2.5 to 0.5 J/m2·s. It is suggested that solar-UV radiation would not influence the cell growth of P. tetraurelia for the reason of high PR activity even when the ozone concentration was decreased 30% from the present levels. [source] Dose rate effects on the thermoluminescence kinetics properties of MWCVD diamond filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2007S. Gastélum Abstract Dose rate effects are important in thermoluminescent (TL) dosimeter applications because a certain absorbed dose given at different dose rates may result in a different TL yield. The present work reports about the dose rate effects on TL glow curves and kinetics properties of microwave plasma assisted chemical vapor deposition (MWCVD) diamond films grown on (100) silicon. The diamond films were exposed to , radiation at 20.67, 43.4 and 81.11 Gy min,1 dose rates in the range of 0.05,10 kGy. The films showed a linear dose behavior up to 2 kGy and reached saturation for higher doses. The TL intensity varied as a function of dose rate and the samples had a maximum TL response for relatively lower dose rates. A single first order kinetics TL peak was typical for low doses while at higher doses two first order kinetics peaks were necessary to fit the glow curves. The results indicate that dose rate effects may be significant in dosimetric applications of MWCVD diamond. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Methacryloxyethyl phosphate-grafted expanded polytetrafluoroethylene membranes for biomedical applicationsPOLYMER INTERNATIONAL, Issue 12 2005Edeline Wentrup-Byrne Abstract Expanded polytetrafluoroethylene (ePTFE) membranes were modified by graft copolymerization with methacryloxyethyl phosphate (MOEP) in methanol and 2-butanone (methyl ethyl ketone (MEK)) at ambient temperature using gamma irradiation. The effect of dose rate (0.46 and 4.6 kGy h,1), monomer concentration (1,40 %) and solvent were studied and the modified membranes were characterized by weight increase, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). XPS was used to determine the % degree of surface coverage using the CF (ePTFE membrane) and the CC (MOEP graft copolymer) peaks. Grafting yield, as well as surface coverage, were found to increase with increasing monomer concentration and were significantly higher for samples grafted in MEK than in methanol solution. SEM images showed distinctly different surface morphologies for the membranes grafted in methanol (smooth) and MEK (globular), hence indicating phase separation of the homopolymer in MEK. We propose that in our system, the non-solvent properties of MEK for the homopolymer play a more important role than solvent chain transfer reactions in determining grafting outcomes. Copyright © 2005 Society of Chemical Industry [source] Comparative study of the radiation-induced grafting of styrene onto poly(tetrafluoroethylene- co -perfluoropropylvinyl ether) and polypropylene substrates.POLYMER INTERNATIONAL, Issue 5 2003I: Kinetics, structural investigation Abstract A comparative study has been made of the radiation grafting of styrene onto poly(tetrafluoroethylene- co -perfluoropropyl vinyl ether) (PFA) and polypropylene (PP) substrates, using the simultaneous irradiation method. Effects of grafting conditions such as monomer concentrations, type of solvent, dose rate and irradiation dose on the grafting yield were investigated. Under the same grafting conditions it was found that a higher degree of grafting of styrene was obtained using a mixture of dichloromethane/methanol solvents for PFA and methanol for PP and the degree of grafting was higher in PP than in PFA at all doses. However, the micro-Raman spectroscopy analysis of the graft revealed that, for the same degree of grafting, the penetration depth of the grafted polystyrene into the substrate was higher in PFA than in PP substrates. In both polymers the crystallinity was hardly affected by the grafting process and the degree of crystallinity decreased slightly with grafting dose. The dependence of the initial rate of grafting on the dose rate and the monomer concentration was found to be 0.6 and 1.4 order for PFA and 0.15 and 2.2 for PP, respectively. The degree of grafting increased with increasing radiation dose in both polymers. However, the grafting yield decreased with an increase in the dose rate. The increase in the overall grafting yield for PFA and PP was accompanied by a proportional increase in the penetration depth of the graft into the substrates. Copyright © 2003 Society of Chemical Industry [source] Surgical removal of an ovarian tumour in a koi carp (Cyprinus carpio)AUSTRALIAN VETERINARY JOURNAL, Issue 5 2006SR RAIDAL Ultrasonography, radiography and exploratory coeliotomy were used to diagnose and treat a large intracoelomic neoplasm from a female koi carp (Cyprinus carpio) presented for abdominal enlargement of several months duration. Feed was withheld for 1 week immediately prior to surgery and the fish was sedated with isoeugenol (AQUI-S®) at a dose rate of 10 mL/L to facilitate diagnostic imaging techniques. Surgical anaesthesia was induced by adding tricaine (MS-222) 50 mg/L to the water and an exploratory coeliotomy and tumour removal was performed. The fish was allowed to recover in fresh water at 18°C and salt was added slowly to the water over a period of 1 hour to a concentration of 5 g/L This concentration was maintained in a recovery pond for 1 week postoperatively. Enrofloxacin was administered intramuscularly (10 mg/kg) immediately, 3 days and 1 week postoperatively. A diagnosis of undifferentiated ovarian carcinoma was made on the basis of the histological appearance of the neoplasm and immunohistochemical staining. [source] Radiolysis of Confined Water: Hydrogen Production at a High Dose RateCHEMPHYSCHEM, Issue 12 2005Sophie Le Caër Dr. Abstract The production of molecular hydrogen in the radiolysis of dried or hydrated nanoporous controlled-pore glasses (CPG) has been carefully studied using 10 MeV electron irraditation at high dose rate. In all cases, the H2 yield increases when the pore size decreases. Moreover, the yields measured in dried materials are two orders of magnitude smaller than those obtained in hydrated glasses. This proves that the part of the H2 coming from the surface of the material is negligible in the hydrated case. Thus, the measured yields correspond to those of nanoconfined water. Moreover, these yields are not modified by the presence of potassium bromide, which is a hydroxyl radical scavenger. This experimental observation shows that the back reaction between H2 and HO. does not take place in such confined environments. These porous materials have been characterized before and after irradiation by means of Fourier-transform infrared (FT-IR) spectroscopy, electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) techniques, which helps to understand the elementary processes taking place in this type of environment, especially the protective effect of water on the surface in the case of hydrated glasses. [source] Radiation doses to staff involved in sentinel node operations for breast cancerCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 4 2005T. L. Klausen Summary Background:, The use of radioactive compounds for sentinel node biopsy is now a generally accepted part of the surgical treatment of breast cancer and melanoma, with the risk of radiation exposure to the operating team. The aim of this investigation was to study the levels of this exposure in relation to the permissible radiation dose limits. Methods:, The radiation exposure to the hands and bodies of the operating surgeons (the ,risk persons') was measured by thermoluminescent dosemeters in 79 operations and to the pathologists handling the specimens in 17 cases. Radioactivity and dose rate measurement from tumours and breast specimens were also performed. Results:, During an operation the mean skin dose (±SD) to the thermoluminescent dosemeters placed at the hand and the abdominal wall were 0·04 ± 0·04 mSv (79 operations) and 0·01 ± 0·02 mSv (67 operations) respectively. For the pathologist, the mean hand dose per operation was below the detection limit (17 operations). Correlation between the measured dose rate and the radioactive content of the tumours was 0·998. Conclusions:, The radiation exposure to the staff involved in sentinel node (SN) biopsy for breast cancer using radioactive labelled tracers will be considerably below the permissible limits, even with high numbers of SN biopsy procedures. Pregnant staff members should participate in <100 SN operations. [source] A web-based decision support system for integrated management of weeds in cereals and sugarbeet,EPPO BULLETIN, Issue 3 2003P. Rydahl A Danish decision support system (DSS) named Crop Protection Online (CPO) for integrated management of weeds in cereals and beet has been developed during the past 20 years. CPO is based on a model that runs in three main steps: model step 1 quantifies the level of weed control needed on a field level, model step 2 selects candidate herbicides and calculates dose rates to meet the need, and model step 3 calculates tank mixtures of herbicides with two to four mixing components, if advantageous. CPO has been developed in cereals and beet, and various prototype versions have been validated in 1679 field tests. CPO secured yield potentials, and the level of residual weeds was not increased when compared with reference treatments. The potential of CPO to reduce herbicide use has been observed in all model crops, but the potential was greatest in cereals. In spring cereal field trials highly infested with weeds, the present version of CPO suggested 35% of one full herbicide dose on average and in winter cereals CPO suggested 44% on average of one full dose. The results from validation trials demonstrate that CPO is capable of suggesting robust treatment options with a low input of herbicides. The system architecture of CPO has been exported to Poland and the Baltic countries, and the system is expected to be suitable for export to other countries too. [source] The effects of calcium on stem lesions of silver birch seedlingsFOREST PATHOLOGY, Issue 2 2007A. Lilja Summary In this study, we tested the hypothesis that decreased liming of growth medium has a role in the increase of stem lesions and top dying caused by Phytophthora cactorum in containerized silver birch seedlings (Betula pendula) in Finnish forest nurseries. The effect of limestone dose rates on growth and the nutrient status was also monitored. An index based on severity of symptom expression was used to compare the effect of different liming treatments on P. cactorum infection. Limestone amended into the sphagnum peat growth medium increased the amount of calcium in the seedling stems. Liming did not significantly decrease the disease severity although index values in most cases decreased with the increased limestone dose rates. In general, the lesions were restricted after out-planting and the mortality of seedlings was low. Only inoculated seedlings on which the lesions had spread around the stem in the nursery died. Phytophthora cactorum appears to be a nursery pathogen, as it did not survive under conditions present in the field. Four years after out-planting, the tallest birches were those grown in sphagnum peat amended with the highest limestone dose of 8 kg m,3. [source] Reversible addition,fragmentation chain-transfer graft polymerization of styrene: Solid phases for organic and peptide synthesisJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2002Leonie Barner Abstract The ,-initiated reversible addition,fragmentation chain-transfer (RAFT)-agent-mediated free-radical graft polymerization of styrene onto a polypropylene solid phase has been performed with cumyl phenyldithioacetate (CPDA). The initial CPDA concentrations range between 1 × 10,2 and 2 × 10,3 mol L,1 with dose rates of 0.18, 0.08, 0.07, 0.05, and 0.03 kGy h,1. The RAFT graft polymerization is compared with the conventional free-radical graft polymerization of styrene onto polypropylene. Both processes show two distinct regimes of grafting: (1) the grafting layer regime, in which the surface is not yet totally covered with polymer chains, and (2) a regime in which a second polymer layer is formed. Here, we hypothesize that the surface is totally covered with polymer chains and that new polymer chains are started by polystyrene radicals from already grafted chains. The grafting ratio of the RAFT-agent-mediated process is controlled via the initial CPDA concentration. The molecular weight of the polystyrene from the solution (PSfree) shows a linear behavior with conversion and has a low polydispersity index. Furthermore, the loading of the grafted solid phase shows a linear relationship with the molecular weight of PSfree for both regimes. Regime 2 has a higher loading capacity per molecular weight than regime 1. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4180,4192, 2002 [source] Biofortification of lettuce (Lactuca sativa L.) with iodine: the effect of iodine form and concentration in the nutrient solution on growth, development and iodine uptake of lettuce grown in water cultureJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 5 2010Wim Voogt Abstract BACKGROUND: Iodine is an essential trace element for humans. Two billion individuals have insufficient iodine intake. Biofortification of vegetables with iodine offers an excellent opportunity to increase iodine intake by humans. The main aim was to study the effect of iodine form and concentration in the nutrient solution on growth, development and iodine uptake of lettuce, grown in water culture. RESULTS: In both a winter and summer trial, dose rates of 0, 13, 39, 65, and 90 or 129 µg iodine L,1, applied as iodate (IO3,) or iodide (I,), did not affect plant biomass, produce quality or water uptake. Increases in iodine concentration significantly enhanced iodine content in the plant. Iodine contents in plant tissue were up to five times higher with I, than with IO3,. Iodine was mainly distributed to the outer leaves. The highest iodide dose rates in both trials resulted in 653 and 764 µg iodine kg,1 total leaf fresh weight. CONCLUSION: Biofortification of lettuce with iodine is easily applicable in a hydroponic growing system, both with I, and IO3,. I, was more effective than IO3,. Fifty grams of iodine-biofortified lettuce would provide, respectively, 22% and 25% of the recommended daily allowance of iodine for adolescents and adults. Copyright © 2010 Society of Chemical Industry [source] The pharmacokinetics and pharmacodynamics of alfaxalone in cats after single and multiple intravenous administration of Alfaxan® at clinical and supraclinical dosesJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 6 2008T. WHITTEM This study aimed to determine the pharmacokinetic parameters and pharmacodynamics of alfaxalone in a 2-hydroxypropyl-,-cyclodextrin alfaxalone formulation (Alfaxan®, Jurox Pty Ltd, Rutherford, NSW, Australia) in cats after single administration at clinical and supraclinical dose rates and as multiple maintenance doses. First, a prospective two-period cross-over study was conducted at single clinical and supraclinical doses. Second, a single group multiple dose study evaluated the effect of maintenance doses. Eight (five female and three male) domestic cats completed the cross-over experiment and six female cats completed the multiple dose study. In the first experiment, alfaxalone was administered intravenously (IV) at 5 or 25 mg/kg with a washout period of 14 days. In the second experiment, alfaxalone was administered IV at 5 mg/kg followed by four doses each of 2 mg/kg, administered at onset of responsiveness to a noxious stimulus. Blood was collected at prescribed intervals and analysed by LCMS for plasma alfaxalone concentration. Noncompartmental pharmacokinetics were used to analyse the plasma alfaxalone data. The plasma clearance of alfaxalone at 5 and 25 mg/kg differed statistically at 25.1 and 14.8 mL/kg/min respectively. The elimination half lives were 45.2 and 76.6 min respectively. Alfaxalone has nonlinear pharmacokinetics in the cat. Nevertheless, for cats dosed with sequential maintenance doses, a regression line through their peak plasma concentrations indicated that there was no clinically relevant pharmacokinetic accumulation. The duration of nonresponsiveness after each maintenance dose was similar at approximately 6 min, indicating a lack of accumulation of pharmacodynamic effect. The cardiovascular and respiratory parameters measured in cats after administration of the labelled doses of Alfaxan® were stable. In conclusion, the pharmacokinetics of alfaxalone in cats are nonlinear. At clinical dose rates, however, neither alfaxalone nor its effects accumulated to a clinically relevant extent. Further, in the un-premedicated cat the induction and maintenance of surgical anaesthesia was free of untoward events after a dose of 5 mg alfaxalone/kg body weight followed by four sequential doses of 2 mg/kg as needed (i.e., approximately 7 to 8 mg/kg/h). [source] The influence of the extensional viscosity of very low concentrations of high molecular mass water-soluble polymers on atomisation and droplet impactPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 5 2008Peter A Williams BACKGROUND: Water-soluble polymers are increasingly added to herbicide and pesticide formulations at very low concentrations (100,1000 mg L,1) in order to control the spray characteristics, notably to reduce spray drift and influence droplet bounce. The incorporation of polymeric adjuvants improves the efficacy of the spray solutions, thus enabling crop growers to maximise the performance of agrochemical sprays at lower dose rates of active ingredient. It is important to establish a fundamental understanding of how polymers influence the processes involved in droplet deposition. RESULTS: The shear and extensional viscosities of a series of high molecular mass (Mw) poly(acrylamides) (Mw , 106,107) have been determined at very low concentrations (100,1000 mg L,1). The polymer solutions demonstrated typical shear thinning characteristics under shear, and strain hardening behaviour under extension above a critical strain rate. The presence of the polymers was shown to increase the size of droplets produced in atomisation using an agricultural spray nozzle, as measured by laser diffraction. This was attributed to the increase in the extensional viscosity at the strain rates generated under pressure in the spray nozzle and was a function of both polymer concentration and Mw. In addition, the presence of polymer was found to have a significant influence on droplet bounce. CONCLUSIONS: The presence of very low concentrations of high molecular mass poly(acrylamides) significantly influences the size of droplets formed on atomisation and subsequent bounce characteristics. Large extensional viscosities generated above a critical strain rate are responsible for both processes. Copyright © 2008 Society of Chemical Industry [source] Dose rate effects on the thermoluminescence kinetics properties of MWCVD diamond filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2007S. Gastélum Abstract Dose rate effects are important in thermoluminescent (TL) dosimeter applications because a certain absorbed dose given at different dose rates may result in a different TL yield. The present work reports about the dose rate effects on TL glow curves and kinetics properties of microwave plasma assisted chemical vapor deposition (MWCVD) diamond films grown on (100) silicon. The diamond films were exposed to , radiation at 20.67, 43.4 and 81.11 Gy min,1 dose rates in the range of 0.05,10 kGy. The films showed a linear dose behavior up to 2 kGy and reached saturation for higher doses. The TL intensity varied as a function of dose rate and the samples had a maximum TL response for relatively lower dose rates. A single first order kinetics TL peak was typical for low doses while at higher doses two first order kinetics peaks were necessary to fit the glow curves. The results indicate that dose rate effects may be significant in dosimetric applications of MWCVD diamond. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Is radiation damage dependent on the dose rate used during macromolecular crystallography data collection?ACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2006Hanna-Kirsti S. Leiros This paper focuses on the radiation-damage effects when applying the same total X-ray dose to protein crystals at different dose rates. These experiments have been performed on both a selenomethionated protein and on bovine trypsin using dose rates that span nearly two orders of magnitude. The results show no clear dose-rate effect on the global indicators of radiation damage, but a small measurable dose-rate effect could be found when studying specific radiation damage. It is hypothesized that this observed dose-rate effect relates to differences in the steady-state free-radical concentration. [source] Veterinarians' preferences for anticonvulsant drugs for treating seizure disorders in dogs and catsAUSTRALIAN VETERINARY JOURNAL, Issue 11 2009EK Kluger Objective To identify veterinarians' approaches and concerns when managing canine and feline patients with acute and chronic seizure disorders. Design Cross-sectional survey. Method A questionnaire was distributed to veterinarians to determine how many dogs and cats they were actively treating for seizures, their anticonvulsant drug (ACD) preferences for treating acute and chronic seizure disorders and whether serum anticonvulsant concentrations and/or biochemical analytes were routinely measured. Additional questions involved the respondent's year and place of graduation and identified concerns they faced when managing patients with seizure disorders. Results Phenobarbitone was the most commonly used ACD for managing chronic seizure disorders in both dogs and cats, with 82% of respondents using a combination of phenobarbitone and potassium bromide to manage refractory seizure disorders in dogs. Most respondents (96%) felt comfortable managing seizures in dogs, but only 63% were comfortable managing affected cats. Routine monitoring of serum ACD concentrations and of liver biochemical analytes was performed routinely by 71% and 45% of respondents, respectively. Of the respondents, 86% graduated from Australian universities and of these 53% had graduated after 1985. Conclusion Veterinarians identified when to commence medication, whether regular monitoring of serum ACD concentrations and liver enzyme activity was necessary, and if the cost was justified. Veterinarians also identified the need to balance dose rates and side-effects by using combination therapy, and the importance of providing accurate information to clients about what to expect in terms of seizure control for their pet. [source] | |||||||||||||||||||