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Selected AbstractsNovel Thorium Membrane Sensors with Anionic Response Based on Trioctylphosphine Oxide and Toluate IonophoresELECTROANALYSIS, Issue 19 2008Abstract Two novel potentiometric polymeric membrane sensors for rapid and accurate determination of thorium are described. These are based on the use of trioctylphosphine oxide (TOPO) and thorium toluate (Th-TA) as ionophores dispersed in poly(vinyl chloride) matrix membranes plasticized with nitrophenyloctyl ether. In strong nitric acid medium, Th(IV) nitrate is converted into [Th(NO3)6]2, complex and sensed as anionic divalent ion which exclude most cationic effect. Validation of the assay methods using the quality assurance standards (linearity range, accuracy, precision, within-day variability, between-day-repeatability, lower detection limit and sensitivity) reveals excellent performance characteristics of both sensors. The sensors exhibit near-Nernstian response for 1.0×10,6,1.0×10,1 M Th over the pH range 2.5,4.5. Calibration slopes of ,32.3±0.3 and ,27.2±0.2,mV/decade, precision of ±0.5 and ±0.8% and accuracy of 98.8±0.9 and 97.9±0.7% are obtained with TOPO and Th-TA based sensors, respectively. Negligible interferences are caused by most interfering mono-, di-, tri-, tetra-, penta-, and hexa-valent elements commonly associated with thorium in naturally occurring minerals and ores. High concentrations of Cl,, F,, SO42,, and NO3, ions have no diverse effect. Complete removal of the effect of the interferents in complex matrices is achieved by retention of [Th(NO3)6]2, complex from 5,M nitric acid/methanol mixture (1,:,9,v/v) on a strong anion exchanger, washing out the cationic interferents followed by stripping off thorium anion complex and measurements. Both sensors are used for determining thorium in certified thorium ore samples (20,120,mg Th/kg) and some naturally occurring ores (200,600,mg Th/kg). The results obtained agree fairly well with the certified labeled values or the data obtained using X-ray fluorescence spectrometry [source] Laryngeal schwannoma in an 8-year-old boy with inspiratory dyspneaHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 10 2007Elisa Rognone MD Abstract Background Schwannomas of the larynx are rare lesions in the pediatric age group. Methods In this article, we report on the neuroimaging features of a schwannoma arising from the left aryepiglottic fold in an 8-year-old boy with a 6-month history of inspiratory dyspnea. Results Neuroimaging showed a well-defined, avoid mass originating from the left aryepiglottic fold. The lesion was removed endoscopically. Conclusion Complete removal of laryngeal schwannomas is curative, and adjuvant treatment is not required. © 2007 Wiley Periodicals, Inc. Head Neck, 2007 [source] Efficacy of three rotary NiTi instruments in removing gutta-percha from root canalsINTERNATIONAL ENDODONTIC JOURNAL, Issue 3 2008T. Ta, demir Abstract Aim, To investigate the ability of three rotary nickel,titanium instruments and hand instrumentation to remove gutta-percha and sealer. Methodology, Sixty freshly extracted human single-rooted teeth, each with one root canal, were instrumented with K-files and filled using cold lateral compaction of gutta-percha and AH Plus (Dentsply Detrey, Konstanz, Germany) sealer. The teeth were randomly divided into four groups of 15 specimens each. Removal of gutta-percha was performed with the following devices and techniques: ProTaper, R-Endo, Mtwo and Hedström files. The specimens were rendered transparent and the area of remaining filling material on the root canal wall was measured using a computer image analysis program. Statistical analysis was accomplished by Kruskal,Wallis and Mann,Whitney U -tests with Bonferroni correction for the analysis of residual root filling material and working time. Results, The ProTaper group had less filling material inside the root canals than the other groups, but a significant difference was found between only the ProTaper and Mtwo groups (P < 0.05). The retreatment time for Mtwo and ProTaper was significantly shorter compared with R-Endo and manual instrumentation with Hedström files (P < 0.001). R-Endo was significantly faster than manual instrumentation (P < 0.001). Conclusions, Under the experimental conditions, ProTaper left significantly less gutta-percha and sealer than Mtwo instruments. Complete removal of materials did not occur with any of the instrument systems investigated. [source] A fish bone embedded in the mobile tongue mimicking a neoplasmORAL SURGERY, Issue 4 2008Yan Wang Abstract Foreign bodies embedded in a mobile tongue as an enlarged tongue mass are rarely presented to either a laryngologist or a dentist, because such bodies are commonly lodged superficially and are easily removed by the patients themselves or removed by a laryngologist by means of indirect laryngoscope or endoscope. We have described a 63-year-old female with an 8-month history of an enlarged mass in the anterior right tongue. Physical examination demonstrated a mass located in the anterior right tongue without clear margin, with superficially intact mucosa and normal colour. A benign tongue neoplasm was first considered. However, a fish bone totally embedded in the mobile tongue with granuloma formation was encountered during the incisional biopsy operation. Complete removal of the foreign body with granuloma was achieved under general anaesthesia. There was no neuromuscular or neurosensory dysfunction of the tongue in the follow-up period of 2 years. Although an embedded foreign body in the mobile tongue is a rare condition, it should be considered in the work-up of a patient with an enlarged tongue mass, with or without a history of swallowing a foreign body. [source] Minimal-Scar Segmental Extraction of Lipomas: Study of 122 Consecutive ProceduresDERMATOLOGIC SURGERY, Issue 1 2005Rajiv Y. Chandawarkar MD Background Surgical extirpation of lipomas that occur in cosmetically conspicuous areas of the body leaves a visible scar that is usually disfiguring. Minimal-scar segmental extraction (MSE) employs a much smaller incision and extraction and is particularly useful in exposed parts of the body. It can be easily performed in an office setting. Objective The objective of this study was to evaluate the merits of MSE in clinical practice. Unlike other reports in the literature that describe, anecdotally, minimally invasive methods of lipoma removal, our study examined a new method by carefully measuring the results in a larger group of consecutive patients treated using this technique. Materials and Methods A retrospective study was performed using data from 91 consecutive patients with a total of 122 lipomas that were treated using MSE. MSE of lipomas consists of a small stab incision and blind dissection of the tumor followed by its extraction in a segmental fashion. This procedure involves small instrumentation, minimal dissection with preservation of contour, and complete removal of the lipoma, including substantial portions of the capsule. Clinical data, including complications, outcomes, and recurrence rates, were recorded. Results The procedure was well tolerated by patients, who were pleased with the results, particularly the small scar. The incidence of complications was 1.6% (n= 2) and consisted of hematoma (n= 1) and seroma (n= 1). The recurrence rate was 0.8% (n= 1). No long-term morbidity was noted. Conclusions The technical ease with which the MSE can be performed, coupled with a low recurrence rate, makes it a very cost-effective operation. The smaller postoperative scars, rapid healing, and low morbidity allow for better patient acceptance. We recognize the advantages and limitations of this procedure and encourage its use in selected patients. RAJIV Y. CHANDAWARKAR, MD, PEDRO RODRIGUEZ, MD, JOHN ROUSSALIS, MD, AND M. DEVIPRASAD TANTRI, MD, HAVE INDICATED NO SIGNIFICANT INTEREST WITH COMMERCIAL SUPPORTERS. [source] Application of supercritical fluid extraction to regenerate spent Pd-active carbon catalystENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 4 2007Lidia D Abstract Pd-active carbon-type catalysts are used in a wide variety of processes, typical examples of which are liquid-phase hydrogenation reactions. In the case of these catalysts, a loss of their catalytic activity is observed. The aim of the present work was to assess the possibility of regenerating spent Pd/AC catalysts using supercritical fluid extraction. The following Pd/AC catalyst samples were investigated and compared: a commercial 10 wt % Pd catalyst (Aldrich) (denoted by CC), a spent catalyst (SC), SC subjected to supercritical fluid,CO2 extraction (SC/SFE/C), SC subjected to supercritical fluid,CO2,ethanol extraction (SC/SFE/C-Et), and SC subjected to supercritical fluid,ethane,propane extraction (SC/SFE/E-P). The last three catalysts were additionally subjected to heating in a hydrogen atmosphere at 410 K for 3 h. These were denoted by SC/SFE/C/H, SC/SFE/C-Et/H, and SC/SFE/E-P/H, respectively. The spent Pd/AC catalyst (SC) consists of mixed CC samples used in the reduction with hydrogen of various organic compounds. The catalysts CC, SC/SFE/C, SC/SFE/C/H, SC/SFE/C-Et/H, and SC/SFE/E-P/H were tested in the reduction of octanoylbenzene with hydrogen. The activity of the catalysts was estimated by measuring the reaction time and also the amount of hydrogen used in relation to the theoretical quantity required for the reaction. XPS and XRD methods were used to evaluate the changes occurring in the form of the palladium present on the Pd/AC catalyst surface during the regeneration processes. It was found that supercritical fluid-CO2 extraction followed by heating in a hydrogen atmosphere is the most effective method for regenerating that catalyst. The results of our investigations indicate that regeneration of a spent Pd/AC catalyst, irrespective of the reaction in which it has been used, should be based on the complete removal of byproducts, the purification of the catalyst surface, and the restoration of the original form of the palladium. The procedure proposed in this paper, i.e. SFE (CO2) and heating in H2, fulfils both the conditions mentioned above. © 2007 American Institute of Chemical Engineers Environ Prog, 2007 [source] Organic carbon biostimulates rapid rhizodegradation of perchlorateENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2008Dawit D. Yifru Abstract Previous hydroponics and field studies identified phytodegradation and rhizodegradation as the two main mechanisms by which plants metabolize perchlorate. Plant uptake and phytodegradation of perchlorate is a slower and undesired process that poses ecological risks resulting from phytoaccumulation of some fraction of the perchlorate. Meanwhile, rhizodegradation is a more rapid and favored process involving perchlorate-degrading bacteria utilizing dissolved organic carbon (DOC) as a carbon and energy (electron) source to rapidly degrade perchlorate to innocuous chloride. In the present study, rhizodegradation of perchlorate by willow trees (Salix nigra) was biostimulated using electron sources obtained from natural and artificial carbon sources. In bioreactors provided with carbon sources as 500 mg/L DOC, 25 to 40 mg/L of initial perchlorate concentrations were removed to below the ion chromatography method detection limit of 2 ,g/L in approximately 9 d. For planted controls provided with no electron donors, the time required for the complete removal of the same doses of perchlorate was up to 70 d. Enhancement of rhizodegradation by organic carbon reduced the phytoaccumulated fraction of perchlorate by an order of magnitude from approximately 430 to 20 mg/ kg. The implication of the present study is that the high fraction uptake and phytoaccumulation of perchlorate in agricultural products and the recycling of perchlorate into the ecosystem can be significantly curtailed by supplying electron donors derived from organic carbon sources to the root zone of plants. [source] Reduction of perchlorate in river sedimentENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2006Rupert Simon Abstract The transformation of perchlorate was investigated in river sediment during laboratory batch and column studies to determine if reduction of perchlorate is a viable pathway in natural sediment without previous exposure to perchlorate. Perchlorate at an initial concentration of 10 ,M was reduced quantitatively to chloride in 3 d after a lag phase of 2 d in sediment slurries amended with lactate. Raising the initial concentration of perchlorate to 1,000 ,M increased the lag phase to 20 d before reduction occurred. At perchlorate concentrations greater than 1,000 ,M, the reduction of perchlorate was not observed within 40 d. We speculate that the high concentration of perchlorate specifically was problematic to the microbes mediating the reduction of perchlorate. High levels of nitrate inhibited the reduction of perchlorate as well. In sediment slurries amended with 870 ,M sodium nitrate, the reduction of perchlorate at an initial concentration of 100 ,M did not occur before day 15 of the experiment, but complete removal of nitrate had occurred by day four. Sediment column studies further demonstrated the dependence of perchlorate reduction on endogenous nitrate levels. [source] Complete elimination of carbonates: A critical step in the accurate measurement of organic and black carbon in sedimentsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2005Marta T. Lukasewycz Abstract Accurate measurement of organic carbon (OC) and black carbon (BC) in sediments requires the complete removal of coexisting inorganic carbonates from the sample before instrumental analysis. The removal of carbonates from sediments is achieved with acidification, which causes the dissolution and decomposition of carbonates with accompanying effervescence. This effervescence, or the lack of it, is commonly used as an indicator for the presence or absence of carbonates. We have found that the lack of effervescence endpoint used with the direct acidification method (adding aliquots of acid to samples) is not a reliable indicator for complete removal of carbonates from sediment samples. The ineffectiveness of the lack of effervescence endpoint, we believe, is caused by the presence of carbonates with dissolution rates much slower than those of calcite, resulting in much slower rates of visible effervescence. We propose and demonstrate a method for determining the amount of acid required for complete elimination of all carbonates using Lake Michigan (USA) sediment samples. Based on our experiences with the lack of effervescence endpoint, we recommend that in any scheme for analysis of OC and/or BC, a minimum of two samples be treated with three different levels of acidification, with the lowest level being the same as that planned for all the OC and/or BC analyses. There can be no significant differences among the OC and BC contents measured using the three different levels of acidification. [source] Seizure Outcome after Resection of Cavernous Malformations Is Better When Surrounding Hemosiderin-stained Brain Also Is RemovedEPILEPSIA, Issue 3 2006Christian R. Baumann Summary:,Purpose: Considering the epileptogenic effect of cavernoma-surrounding hemosiderin, assumptions are made that resection only of the cavernoma itself may not be sufficient as treatment of symptomatic epilepsy in patients with cavernous malformations. The purpose of this study was to test the hypothesis whether seizure outcome after removal of cavernous malformations may be related to the extent of resection of surrounding hemosiderin-stained brain tissue. Methods: In this retrospective study, 31 consecutive patients with pharmacotherapy-refractory epilepsy due to a cavernous malformation were included. In all patients, cavernomas were resected, and all patients underwent pre- and postoperative magnetic resonance imaging (MRI). We grouped patients according to MRI findings (hemosiderin completely removed versus not/partially removed) and compared seizure outcome (as assessed by the Engel Outcome Classification score) between the two groups. Results: Three years after resection of cavernomas, patients in whom hemosiderin-stained brain tissue had been removed completely had a better chance for a favorable long-term seizure outcome compared with those with detectable postoperative hemosiderin (p = 0.037). Conclusions: Our study suggests that complete removal of cavernoma-surrounding hemosiderin-stained brain tissue may improve epileptic outcome after resection of cavernous malformations. [source] Evolution of Electrical, Chemical, and Structural Properties of Transparent and Conducting Chemically Derived Graphene Thin FilmsADVANCED FUNCTIONAL MATERIALS, Issue 16 2009Cecilia Mattevi Abstract A detailed description of the electronic properties, chemical state, and structure of uniform single and few-layered graphene oxide (GO) thin films at different stages of reduction is reported. The residual oxygen content and structure of GO are monitored and these chemical and structural characteristics are correlated to electronic properties of the thin films at various stages of reduction. It is found that the electrical characteristics of reduced GO do not approach those of intrinsic graphene obtained by mechanical cleaving because the material remains significantly oxidized. The residual oxygen forms sp3 bonds with carbon atoms in the basal plane such that the carbon sp2 bonding fraction in fully reduced GO is ,0.80. The minority sp3 bonds disrupt the transport of carriers delocalized in the sp2 network, limiting the mobility, and conductivity of reduced GO thin films. Extrapolation of electrical conductivity data as a function of oxygen content reveals that complete removal of oxygen should lead to properties that are comparable to graphene. [source] Measuring Similarity Among Various Shapes Based on Geometric MatchingGEOGRAPHICAL ANALYSIS, Issue 4 2005Zuoquan Zhao The purpose of this article is to examine how to measure the degree of similarity among various shapes, including for the first time those that are fragmented and perforated, by the overlap-based elongation index. It is argued that complete removal of the effects of position, size, and orientation on shape, which is essential for the calibration of shape similarity, can be achieved by a shape similarity index that varies continuously with changes in shape. After examining the characteristics of shape change, it is demonstrated that the elongation index is sensitive to changes in the shape of two spatial objects only when the centroids of the two objects are coincident. Two related rules of shape similarity are then presented. The applicability of the elongation index is evaluated by comparing several simple and complex shapes. The principal contribution of this article is that for the first time similarity among various shapes, fragmented or perforated, can be identified using the elongation index. [source] The effect of mineral trioxide aggregate on the apexification and periapical healing of teeth with incomplete root formationINTERNATIONAL ENDODONTIC JOURNAL, Issue 1 2006W. T. Felippe Abstract Aim, To evaluate the influence of mineral trioxide aggregate (MTA) on apexification and periapical healing of teeth in dogs with incomplete root formation and previously contaminated canals and to verify the necessity of employing calcium hydroxide paste before using MTA. Methodology, Twenty premolars from two 6-month old dogs were used. After access to the root canals and complete removal of the pulp, the canal systems remained exposed to the oral environment for 2 weeks. Canal preparation was then carried out using Hedström files, under irrigation with 1% sodium hypochlorite, 1 mm short of the radiographic apex. After drying, the canals of two premolars in each dog were left empty (control group). The other eight teeth in each animal were divided into two experimental groups. The apical thirds of the canals of group 1 were filled with MTA. In the teeth of group 2, the canals were dressed with a calcium hydroxide,propylene glycol paste. After 1 week, the paste was removed and the apical third was filled with MTA. All teeth were restored with reinforced zinc oxide cement (IRM) and amalgam. The animals were killed 5 months later, and blocks of the teeth and surrounding tissues were submitted to histological processing. The sections were studied to evaluate seven parameters: formation of an apical calcified tissue barrier, level of barrier formation, inflammatory reaction, bone and root resorption, MTA extrusion, and microorganisms. Results of experimental groups were analysed by Wilcoxon's nonparametric tests and by the test of proportions. The critical value of statistical significance was 5%. Results, Significant differences (P < 0.05) were found in relation to the position of barrier formation and MTA extrusion. The barrier was formed in the interior of the canal in 69.2% of roots from MTA group only. In group 2, it was formed beyond the limits of the canal walls in 75% of the roots. MTA extrusion occurred mainly in roots from group 2. There was similarity between the groups for the other parameters. Conclusions, Mineral trioxide aggregate used after root canal preparation favoured the occurrence of the apexification and periapical healing. The initial use of calcium hydroxide paste was not necessary for apexification to occur, and has shown to be strongly related to the extrusion of MTA and formation of barriers beyond the limits of the root canal walls. [source] The effect of the renewal of calcium hydroxide paste on the apexification and periapical healing of teeth with incomplete root formationINTERNATIONAL ENDODONTIC JOURNAL, Issue 7 2005M. C. S. Felippe Abstract Aim, To evaluate the influence of renewing calcium hydroxide paste on apexification and periapical healing of teeth in dogs with incomplete root formation and previously contaminated canals. Methodology, Forty premolars from four 6-month-old dogs were used. After access to the root canals and complete removal of the pulp, the canal systems remained exposed to the oral environment for 2 weeks. Canal preparation was then carried out using Hedströem files, under irrigation with 1% sodium hypochlorite, 1 mm short of the radiographic apex. After drying, the canals of one premolar in each dog were left empty (group 4-control), and those of the other nine teeth in each animal were filled with a calcium hydroxide-propylene glycol paste. All teeth were restored with reinforced zinc oxide cement (IRM) or IRM and amalgam (group 4). The paste was renewed and the teeth restored again 1 week later. Then, the nine teeth in each animal were divided into three experimental groups: group 1 , paste not changed; group 2 , paste renewed every 4 weeks for 5 months; and group 3 , paste renewed after 3 months had elapsed. The teeth were restored with IRM and amalgam (groups 1 and 3) or IRM (group 2). The animals were killed 5 months later, and blocks of the teeth and surrounding tissues were submitted to histological processing. The sections were studied to evaluate six parameters: apical calcified tissue barrier, inflammatory reaction, bone and root resorption, paste extrusion and microorganisms. Results of experimental groups were analysed by Kruskal,Wallis nonparametric tests and by the test of proportions. The critical value of statistical significance was 5%. Results, Significant differences (P < 0.05) were found in relation to the presence of bone resorption and paste in the periradicular area, the formation of a calcified tissue barrier at the apex, and the intensity of the apical inflammatory reaction. Bone resorption was more evident in group 1 (medicament not changed), and the presence of paste in the periodontal tissues was more common in groups 2 and 3. Renewal of the paste reduced the intensity of the inflammatory reaction (groups 2 and 3), but the formation of apical calcified tissue was more noticeable in the teeth where the paste had not been renewed. Conclusions, Replacement of calcium hydroxide paste was not necessary for apexification to occur, however, it did reduce significantly the intensity of the inflammatory process. Monthly renewal of calcium hydroxide paste reduced significantly the occurrence of apexification. [source] Intraoperative transesophageal echocardiography for inferior vena caval tumor thrombus in renal cell carcinomaINTERNATIONAL JOURNAL OF UROLOGY, Issue 4 2004TAKEHIRO OIKAWA Abstract Background : We investigated the advantages of intraoperative transesophageal echocardiography (TEE) during inferior vena caval tumor thrombectomy in renal cell carcinoma (RCC). Methods : Five patients with RCC that extended into the inferior vena cava (IVC) underwent radical nephrectomy. To remove the tumor thrombus in the IVC, an inflated Fogarty balloon catheter was used to pull the thrombus below the level of the hepatic veins with real-time TEE monitoring. Results : In all cases, TEE monitoring during surgery provided an accurate and excellent view of the IVC thrombus. TEE was particularly helpful for the thrombectomy to minimize hepatic mobilization by using occlusion balloon catheter in two patients whose thrombus extended to the intrahepatic IVC. Conclusions : Intraoperative real-time TEE monitoring is a safe, minimally invasive technique that can provide accurate information regarding the presence and extent of IVC involvement, guidance for placement of a vena caval clamp, confirmation of complete removal of the IVC thrombus and intervention using catheters to assist in thrombectomy. [source] An Evaluation of the Compensation Required by European Union Cereal Growers to Accept the Removal of Price SupportJOURNAL OF AGRICULTURAL ECONOMICS, Issue 3 2003Rob Fraser Motivated by the policy trend of exposing European Union farmers to more market risk by reducing price support, this paper evaluates the compensation required by EU cereal growers to accept the complete removal of price support. Additional considerations are whether this policy change also includes the removal of set-aside, or features only a partial removal of price support. A model is developed which captures the main on- and off-farm factors influencing grower perceptions of the impact of this policy change. This model is subjected to a numerical analysis which shows that divergent assessments of the expected profitability of releasing to production land previously set-aside mean growers are unlikely to agree whether compensation is even required. It is concluded that the retention of set-aside for environmental purposes is likely to mean growers are more united in their perception of the need for, and amount of, compensation to accept the removal of price support. [source] Positional relationships between the masticatory muscles and their innervating nerves with special reference to the lateral pterygoid and the midmedial and discotemporal muscle bundles of temporalisJOURNAL OF ANATOMY, Issue 2 2000KEIICHI AKITA For an accurate assessment of jaw movement, it is crucial to understand the comprehensive formation of the masticatory muscles with special reference to the relationship to the disc of the temporomandibular joint. Detailed dissection was performed on 26 head halves of 14 Japanese cadavers in order to obtain precise anatomical information of the positional relationships between the masticatory muscles and the branches of the mandibular nerve. After complete removal of the bony elements, the midmedial muscle bundle in all specimens and the discotemporal muscle bundle in 6 specimens, derivatives of the temporalis, which insert into the disc were observed. On the anterior area of the articular capsule and the disc of the temporomandibular joint, the upper head of the lateral pterygoid, the midmedial muscle bundle of temporalis and the discotemporal bundle of temporalis were attached mediolaterally, and in 3 specimens the posterosuperior margin of the zygomaticomandibularis was attached to the anterolateral area of the disc. It is suggested that these muscles and muscle bundles contribute to various mandibular movements. Although various patterns of the positional relationships between the muscles and muscle bundles and the their innervating nerves are observed in the present study, relative positional relationships of the muscles and muscle bundles and of nerves of the mandibular nerve are consistent. A possible scheme of the developmental formation of the masticatory muscles based on the findings of the positional relationships between the muscles and the nerves is presented. [source] Comparative corrosion performance of black oxide, sandblasted, and fine-drawn nitinol wires in potentiodynamic and potentiostatic tests: Effects of chemical etching and electropolishingJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2004Svetlana Shabalovskaya Abstract The corrosion performance of sandblasted (SB) and smooth fine-drawn (FD) medical-use nitinol wires was compared with the performance of wires with black oxide (BO) formed in air during their manufacture. Potentiodynamic and ASTM F746 potentiostatic tests in a 0.9 % NaCl solution were conducted on wires in their as-received, chemically etched, aged in boiling water, and electropolished states. As-received wires with various surface finishes revealed breakdown potentials in the range from ,100 mV to +500 mV; similar passive current density, 10,6 A/cm2; and a wide hysteresis on the reverse scan, demonstrating strong susceptibility to localized corrosion. Chemically etched wires with original black oxide displayed consistent corrosion performance and surpassed, in corrosion resistance, electropolished wires that showed significantly lower breakdown (400,700 mV) and localized corrosion potentials (,,50 to +113 mV). Sandblasted and fine-drawn wires exhibited rather inconsistent corrosion behavior. In potentiodynamic tests these wires could perform with equal probability either on the level of pretreated BO wires or rather similar to as-received wires. Both SB and FD wires revealed low breakdown potentials in the PS regime. SEM analysis performed before tests indicated that sandblasting was not efficient for the complete removal of the original scaling, and fine drawing aggravated the situation, resulting in a persistent scaling that contributed to the inferior corrosion performance. Inclusions (oxides, carbides, and oxidized carbides) inherited from the bulk and retained on electropolished surfaces are the cause of their inferior performance compared to chemically etched surfaces. In electropolished wires corrosion was initiated around inclusions. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 223,231, 2004 [source] Repair of ALCAPA in a 4-kg Patient Followed by Successful Weaning and "Off-Pump" Explantation of an Apical Venting Pulsatile LVADJOURNAL OF CARDIAC SURGERY, Issue 3 2005Michael Huebler M.D. Extracorporeal pneumatic pulsatile devices are considered the strategy of choice if long-lasting bridge to recovery or transplantation is expected. However, complete explantation of the device may be complicated by hemorrhage and subsequent transfusions due to the establishment of CPB. The present case demonstrates successful weaning and complete removal of an apical venting pulsatile LVAD in a 4-kg infant without the employment of CPB. [source] Inhibition of sulfide on the simultaneous removal of nitrate and p -cresol by a denitrifying sludgeJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 3 2008Edna R Meza-Escalante Abstract BACKGROUND: Many industrial discharges, such as those generated from petrochemical refineries, contain large amounts of sulfurous, nitrogenous and organic contaminants. Denitrification has emerged as a suitable technology for the simultaneous removal of these pollutants in a single reactor unit; however, more evidence is demanded to clarify the limitations of denitrification on the simultaneous removal of sulfide and phenolic contaminants and to optimize the biological process. The aim of this study was to evaluate the capacity of a denitrifying sludge to simultaneously convert sulfide and p -cresol via denitrification. RESULTS: Sulfide was the preferred electron donor over p -cresol, imposing a 5 h lag phase (required for complete sulfide removal) on organotrophic denitrification. Addition of sulfide (20 mg S2, L,1) to p -cresol-amended denitrifying cultures also decreased the reduction rate of nitrate and nitrite, as well as the production rate of nitrogen gas. Nitrite reduction rate was the most affected step by sulfide, decreasing from 35 to 21 mg N (g VSS d),1. A synergistic inhibitory effect of nitrate and sulfide was also observed on nitrite reduction. Despite the effects of sulfide on the respiratory rates monitored, complete removal of nitrate, sulfide and p -cresol could be achieved after 48 h of incubation. CONCLUSION: Our results suggest that simultaneous removal of sulfide and p -cresol could be achieved in denitrifying reactors, but a large hydraulic residence time may be required to sustain an efficient process due to inhibitory effects of sulfide. Copyright © 2008 Society of Chemical Industry [source] Operating and scale-up factors for the electrolytic removal of algae from eutrophied lakewaterJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 8 2002Catalino G Alfafara Abstract Electrolytic removal of algae was conducted in batch and continuous reactors to investigate operating factors affecting removal efficiency and to explore engineering relationships which could be useful for operation and scale-up. The system integrated both electro-flocculation and electro-flotation mechanisms by using polyvalent metal anodes and inert metal cathodes. Batch reactor studies confirmed that high electrical input power or higher electrical current achieved higher and faster removal efficiencies. Natural liquid circulation was observed during electrolytic operation and increased with higher electrical power. However, a small degree of external mixing may be useful at lower electrical power input. Electro-flotation alone could not achieve complete algae removal (maximum efficiency 40,50%), and showed the importance of algal floc formation for the complete removal of algae. In continuous electrolysis experiments, the ratio of the volumetric current intensity (amperes,dm,3) and the chlorophyll a loading (mg,dm,3,h,1) was found to be a useful operating and scale-up factor to balance high algal removal efficiency with minimum release of excess aluminum. This ratio was eventually found to be just the charge dose or the amount of coulombs required to remove a unit mass of chlorophyll a. The optimum charge dose was determined and used to relate the operating current and electrolysis time of a continuous process. © 2002 Society of Chemical Industry [source] In vitro evaluation of novel low abrasive air polishing powdersJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 1 2003G. J. Petersilka Abstract Aim of the study: Though efficient in stain and plaque removal, air polishing is highly abrasive on root cementum or dentin even if working parameters are adjusted to minimize damage. As abrasiveness is also influenced by the physical properties of the powders used, the aim of the study was to evaluate the safety of novel low abrasive air polishing powders in vitro. Material and methods: Using four novel air polishing powders (A, B, C and D) and a standard sodium bicarbonate (NaHCO3) powder, roots of 126 extracted teeth were air polished under standardized conditions at various working parameter combinations (distance: 2 mm, 4 mm and 6 mm; powder and water setting: low, medium and high) at an angulation of 90° for 20 s. Instrumentation was performed in triplicate; resulting root defects were quantified laser-optically. Results: Mean defect depths after application of powders A, B, C and D were significantly lower than with standard powder (A: 17.9 ± 10.9 µm, B: 48.2 ± 32.7 µm, C: 92.5 ± 57.9 µm, D: 33.9 ± 19.6 µm, NaHCO3: 163.1 ± 71.1 µm) (Kruskal,Wallis test). Among the experimental powders, D was transported most reliably in the air polishing unit and allowed complete removal of disclosed plaque as assessed on freshly extracted teeth. Conclusion: The novel air polishing powder D is of low abrasiveness to root cementum and dentin while being effective in removing dental plaque. Thus, it may be useful for safe and efficient plaque removal on exposed root surfaces. [source] Influence of therapy on the antioxidant status in patients with melanomaJOURNAL OF CLINICAL PHARMACY & THERAPEUTICS, Issue 2 2008V. Gadjeva DSc Summary Background and objective:, Some anticancer drugs can result in increased production of reactive oxygen species (ROS). Alkylating agents are the most frequently used drugs in chemotherapeutic regimens for the treatment of malignant melanoma. It is known that triazenes exhibit in vivo activity by alkylation of nucleic acids and proteins, but there is no data about ROS formation during oxidative metabolism. Single agents of most interest for treatment of malignant melanomas include 5-(3,3-dimethyltriazene-1-yl)-imidazole-4-carboxamide (DTIC) and nitrosoureas such as 1-(2-chloroethyl) -3-cyclohexyl-1-nitrosourea (CCNU), but complete response to these drugs is rare. The present study aimed to determine whether an oxidative stress occurs during the clinical course of melanoma and the influence of therapy on the antioxidant status of patients with melanoma. For this purpose, we investigated plasma concentrations of MDA as indices of the levels of lipid peroxidation products. In addition, we studied the activities of the antioxidant enzymes superoxide dismutases (SOD) and catalase (CAT) in patients with melanoma before any treatment, after surgical removal of melanoma, and after chemotherapy with DTIC or in combination with CCNU of the operated patients. Methods:, Twenty one patients with melanoma were studied. Patients were operated prior to chemotherapy. After recovery for 10,20 days postoperatively, they were studied again for MDA, SOD and CAT activity. The patients were divided into two groups according to the chemotherapy (3,7 treatment cycles): with DTIC , given orally daily for 5 days, every 3 weeks as a single 2200 mg/kg dose and with the combination , DTIC (the same dose) + CCNU , administered orally at a dosage of 120 mg/m2 once every 40 days in accordance with protocols, approved by the Bulgarian Ministry of Health. The total amount of lipid peroxidation products in plasma was assayed. Results and discussion:, Plasma levels of MDA and CAT activity were significantly higher, and erythrocyte SOD activity significantly lower, in patients with melanoma, than in control healthy volunteers (P < 0·0001). Ten to twenty days after surgery, oxidative stress decreased but levels of MDA increased as a result of therapy. Important sources of increased ROS production may be the monocytes, phagocytosis of tumour cells and the cancer tissues. Plasma MDA in patients treated with DTIC + CCNU were significantly higher (P < 0·001), but erythrocyte SOD statistically lower (P < 0·00001), compared with patients treated with DTIC only. However, a combination of DTIC + CCNU did not attenuate oxidative stress, or reduced antioxidant status. Patients treated with this combination are at bigger risk of oxidative injury. Therefore, this disturbance might be due to augmented generation of toxic ROS, possibly from the metabolism of CCNU. Conclusion:, Increased oxidative stress follows an imbalance in antioxidant defence in non-treated patients with melanoma. The impaired antioxidant system favours accumulation of ROS, which may promote the cancer process. After complete removal of melanoma tissues, oxidative stress decreased. The antioxidant status of melanoma patients operated on was influenced by the different chemotherapeutic regimens used and may play an important role in the response. Patients on DTIC + CCNU are at higher risk of oxidative injury. This drug combination probably exerts its toxic activity by ROS, which could be products of the metabolism of CCNU. [source] A simple method for SEM examination of sectioned diatom frustulesJOURNAL OF MICROSCOPY, Issue 1 2001SHORT TECHNICAL NOTE We describe an innovative yet straightforward method to obtain high quality thin sections of diatom exoskeletons for observation by scanning electron microscopy (SEM). The use of this new technique allows for clear observations of some ultrastructural valve features, including the raphe, which are generally difficult to observe and describe accurately using transmission electron microscopy analysis of thin sections or SEM of randomly fractured diatom valves. In addition, because this method involves the complete removal of the organic content of the diatom cells, resulting in clean and mostly undisturbed skeletal thin cross-sections, even the intact valvar structures of weak girdle bands can be studied. [source] Elimination and exchange of trifluoroacetate counter-ion from cationic peptides: a critical evaluation of different approachesJOURNAL OF PEPTIDE SCIENCE, Issue 3 2008Stéphane Roux Abstract Most synthesized peptides are nowadays produced using solid-phase procedures. Due to cleavage and purification conditions, they are mainly obtained in the presence of trifluoroacetic acid (TFA) and, for cationic peptides, as trifluoroacetate (TF-acetate) salts. However, TF-acetate interferes with physicochemical characterizations using infrared spectroscopy and might significantly affect the in vivo studies. Thus, TF-acetate exchange by another counter-ion is often required. Up to now, the classical procedure has consisted of freeze-drying the peptide several times in the presence of an excess of a stronger acid than TFA (pKa ,0): generally HCl (pKa = , 7). This approach means that working at pH < 1 can induce peptide degradation. We therefore tested three different approaches to exchange the tightly bound TF-acetate counter-ion from the dicationic octapeptide lanreotide: (i) reverse-phase HPLC, (ii) ion-exchange resin, and (iii) deprotonation/reprotonation cycle of the amino groups. The first two approaches allow the partial to almost complete exchange of the TF-acetate counter-ion by another ion from an acid weaker than TFA, such as acetic acid (pKa = 4.5), and the third requires a basic solution that permits the complete removal of TF-acetate counter-ion. The efficiency of these three procedures was tested and compared by using different analytical techniques such as 19F-NMR, 1H-NMR and attenuated total reflectance Fourier transformed infrared spectroscopy (ATR FT-IR). We also show that ATR-IR can be used to monitor the TFA removal. The counter-ion exchange procedures described in this study are easy to carry out, fast, harmless and reproducible. Moreover, two of them offer the very interesting possibility of exchanging the initial TF-acetate by any other counter-ion. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd. [source] Measuring the surface area of aluminum hydroxide adjuvantJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 7 2002Cliff T. Johnston Abstract The traditional method of determining surface area, nitrogen gas sorption, requires complete drying of the sample prior to analysis. This technique is not suitable for aluminum hydroxide adjuvant because it is composed of submicron, fibrous particles that agglomerate irreversibly upon complete removal of water. In this study, the surface area of a commercial aluminum hydroxide adjuvant was determined by a gravimetric/FTIR method that measures the water adsorption capacity. This technique does not require complete drying of the adjuvant. Five replicate determinations gave a mean surface area of 514 m2/g and a 95% confidence interval of 36 m2/g for a commercial aluminum hydroxide adjuvant. The X-ray diffraction pattern and the Scherrer equation were used to calculate the dimensions of the primary crystallites. The average calculated dimensions were 4.5,×,2.2,×,10 nm. Based on these dimensions, the mean calculated surface area of the commercial aluminum hydroxide adjuvant was 509 m2/g, and the 95% confidential interval was 30 m2/g. The close agreement between the two surface area values indicates that either method may be used to determine the surface area of aluminum hydroxide adjuvant. The high surface area, which was determined by two methods, is an important property of aluminum hydroxide adjuvants, and is the basis for the intrinsically high protein adsorption capacity. © 2002 Wiley-Liss Inc. and the American Pharmaceutical Association J Pharm Sci 91:1702,1706, 2002 [source] Review: physical chemistry of solid dispersionsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 12 2009Sandrien Janssens Abstract Objectives With poorly soluble drug candidates emerging in the drug discovery pipeline, the importance of the solid dispersion formulation approach is increasing. This strategy includes complete removal of drug crystallinity, and molecular dispersion of the poorly soluble compound in a hydrophilic polymeric carrier. The potential of this technique to increase oral absorption and hence bioavailability is enormous. Nevertheless, some issues have to be considered regarding thermodynamic instability, as well in supersaturated solutions that are formed upon dissolution as in the solid state. Key findings After a brief discussion on the historical background of solid dispersions and their current role in formulation, an overview will be given on the physical chemistry and stability of glass solutions as they form supersaturated solutions, and during their shelf life. Conclusions Thorough understanding of these aspects will elicit conscious evaluation of carrier properties and eventually facilitate rational excipient selection. Thus, full exploitation of the solid dispersion strategy may provide an appropriate answer to drug attrition due to low aqueous solubility in later stages of development. [source] House dust mite allergy: complete removal of the provoking allergen is a primary therapeutic approach*ALLERGY, Issue 9 2009M. V. Kopp No abstract is available for this article. [source] Isolation and characterization of Cupriavidus basilensis HMF14 for biological removal of inhibitors from lignocellulosic hydrolysateMICROBIAL BIOTECHNOLOGY, Issue 3 2010Nick Wierckx Summary The formation of toxic fermentation inhibitors such as furfural and 5-hydroxy-2-methylfurfural (HMF) during acid (pre-)treatment of lignocellulose, calls for the efficient removal of these compounds. Lignocellulosic hydrolysates can be efficiently detoxified biologically with microorganisms that specifically metabolize the fermentation inhibitors while preserving the sugars for subsequent use by the fermentation host. The bacterium Cupriavidus basilensis HMF14 was isolated from enrichment cultures with HMF as the sole carbon source and was found to metabolize many of the toxic constituents of lignocellulosic hydrolysate including furfural, HMF, acetate, formate and a host of aromatic compounds. Remarkably, this microorganism does not grow on the most abundant sugars in lignocellulosic hydrolysates: glucose, xylose and arabinose. In addition, C. basilensis HMF14 can produce polyhydroxyalkanoates. Cultivation of C. basilensis HMF14 on wheat straw hydrolysate resulted in the complete removal of furfural, HMF, acetate and formate, leaving the sugar fraction intact. This unique substrate profile makes C. basilensis HMF14 extremely well suited for biological removal of inhibitors from lignocellulosic hydrolysates prior to their use as fermentation feedstock. [source] House dust mite allergy: complete removal of the provoking allergen is a primary therapeutic approach*ALLERGY, Issue 1 2009M. V. Kopp No abstract is available for this article. [source] | |||||||||||||||||||||||||||||||||||||