Estudio de la siniestralidad vial y diagnóstico de la seguridad vial en el campus de la Universidad de Alicante

OpenAIRE

Martínez Carrillo, Alba

2018-01-01

Este trabajo se ocupa del análisis de la siniestralidad vial y diagnóstico de la seguridad vial en el Campus de la Universidad de Alicante. Para ello, se emplean datos referentes a la accidentalidad vial ocurridos dentro del campus del año 2009 a octubre de 2016, obtenidos gracias a los partes de accidentes facilitados por el Departamento de Seguridad de la Universidad de Alicante. Junto al análisis de esta información, se ha llevado a cabo un trabajo de campo orientado a la seguridad vial pa...

Mathematical methods for quantification and comparison of dissolution testing data.

Science.gov (United States)

Vranić, Edina; Mehmedagić, Aida; Hadzović, Sabira

2002-12-01

In recent years, drug release/dissolution from solid dosage forms has been the subject of intense and profitable scientific developments. Whenever a new solid dosage form is developed or produced, it is necessary to ensure that drug dissolution occurs in an appropriate manner. The pharmaceutical industry and the registration authorities do focus, nowadays, on drug dissolution studies. The quantitative analysis of the values obtained in dissolution/release tests is easier when mathematical formulas that express the dissolution results as a function of some of the dosage forms characteristics are used. This work discusses the analysis of data obtained for dissolution profiles under different media pH conditions using mathematical methods of analysis described by Moore and Flanner. These authors have described difference factor (f1) and similarity factor (f2), which can be used to characterise drug dissolution/release profiles. In this work we have used these formulas for evaluation of dissolution profiles of the conventional tablets in different pH of dissolution medium (range of physiological variations).

Iodination of monoclonal antibodies for diagnosis and radiotherapy using a convenient one vial method

International Nuclear Information System (INIS)

Haisma, H.J.; Hilgers, J.; Zurawski, V.R. Jr.

1986-01-01

We have developed a convenient system that can be used to iodinate monoclonal antibodies for diagnosis or therapy. A vial, previously coated with 1,3,4,6-tetrachloro-3a, 6a-diphenyl glycouril (iodogen), is used as a reaction vessel. Iodination and separation of bound and free iodide, using AG1-X8 ion exchange resin, are both accomplished in this vial. We found 90 +/- 4% of the iodide which was added was incorporated, respectively, into each of four different monoclonal antibodies evaluated. Approximately 90% of labeled antibody was recovered in each case. The monoclonal antibody OC125 was labeled to specific activities up to 25 mCi/mg. Immunoreactivities of 82 +/- 2% using 125 I and 66 +/- 5% using 131 I were achieved. As the radioiodination is done in one sealed vial and takes less than 15 min, this procedure is safe and can be performed in any nuclear medicine laboratory. The final product, which is sterile and apyrogenic, is suitable for diagnostic and radiotherapeutic applications

Polyglycerol coatings of glass vials for protein resistance.

Science.gov (United States)

Höger, Kerstin; Becherer, Tobias; Qiang, Wei; Haag, Rainer; Friess, Wolfgang; Küchler, Sarah

2013-11-01

Proteins are surface active molecules which undergo non-specific adsorption when getting in contact with surfaces such as the primary packaging material. This process is critical as it may cause a loss of protein content or protein aggregation. To prevent unspecific adsorption, protein repellent coatings are of high interest. We describe the coating of industrial relevant borosilicate glass vials with linear methoxylated polyglycerol, hyperbranched polyglycerol, and hyperbranched methoxylated polyglycerol. All coatings provide excellent protein repellent effects. The hyperbranched, non-methoxylated coating performed best. The protein repellent properties were maintained also after applying industrial relevant sterilization methods (≥200 °C). Marginal differences in antibody stability between formulations stored in bare glass vials and coated vials were detected after 3 months storage; the protein repellent effect remained largely stable. Here, we describe a new material suitable for the coating of primary packaging material of proteins which significantly reduces the protein adsorption and thus could present an interesting new possibility for biomedical applications. Copyright © 2013 Elsevier B.V. All rights reserved.

Determination of 226Ra by gamma spectrometry: study of packaging vial of sample for analysis

International Nuclear Information System (INIS)

Carneiro, Andre Cavalcanti

2015-01-01

Determination of radioactivity levels of 226 Ra by gamma spectrometry in a sample is based on measurements of 214 Pb and 214 Bi, daughters of 222 Rn. Because radon is a gas, it can leak from the sample vial or accumulate on the upper empty it. If the vial has any crack, there will be loss of gas, which will cause error in determining the 226 Ra concentration. One possible cause of cracks in the vials, that houses standards and samples, is the radiolysis action in the vial material, usually a polymer. As the demand 226 Ra analysis in different matrices (geological samples, food, plants, etc.) is increasing, it was decided to study some polymer vials available on the market, to verify the feasibility to be used when is applied the analysis method using gamma spectrometry. Four types of polymer vials have been studied. The radiation doses in walls of the vials caused by natural radionuclides present in the sample were simulated using gamma irradiation. Tests, such as compressive strength test and tightness, were applied to the irradiated and non-irradiated vials. First, to verify the effect of radiolysis on the vial material and also if there was 222 Rn diffusion in their walls. These preliminary results pointed out that the acrylic vials are the best option of packaging samples for analysis. This study should be repeated in a larger number of samples for a better evaluation. (author)

Characteristics of MOX dissolution with silver mediated electrolytic oxidation method

Energy Technology Data Exchange (ETDEWEB)

Umeda, Miki; Nakazaki, Masato; Kida, Takashi; Sato, Kenji; Kato, Tadahito; Kihara, Takehiro; Sugikawa, Susumu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2003-03-01

MOX dissolution with silver mediated electrolytic oxidation method is to be applied to the preparation of plutonium nitrate solution to be used for criticality safety experiments at Nuclear Fuel Cycle Safety Engineering Research Facility (NUCEF). Silver mediated electrolytic oxidation method uses the strong oxidisation ability of Ag(II) ion. This method is though to be effective for the dissolution of MOX, which is difficult to be dissolved with nitric acid. In this paper, the results of experiments on dissolution with 100 g of MOX are described. It was confirmed from the results that the MOX powder to be used at NUCEF was completely dissolved by silver mediated electrolytic oxidation method and that Pu(VI) ion in the obtained solution was reduced to tetravalent by means of NO{sub 2} purging. (author)

Dissolution-recrystallization method for high efficiency perovskite solar cells

Energy Technology Data Exchange (ETDEWEB)

Han, Fei; Luo, Junsheng; Wan, Zhongquan; Liu, Xingzhao; Jia, Chunyang, E-mail: cyjia@uestc.edu.cn

2017-06-30

Highlights: • Dissolution-recrystallization method can improve perovskite crystallization. • Dissolution-recrystallization method can improve TiO{sub 2}/perovskite interface. • The optimal perovskite solar cell obtains the champion PCE of 16.76%. • The optimal devices are of high reproducibility. - Abstract: In this work, a dissolution-recrystallization method (DRM) with chlorobenzene and dimethylsulfoxide treating the perovskite films during the spin-coating process is reported. This is the first time that DRM is used to control perovskite crystallization and improve the device performance. Furthermore, the DRM is good for reducing defects and grain boundaries, improving perovskite crystallization and even improving TiO{sub 2}/perovskite interface. By optimizing, the DRM2-treated perovskite solar cell (PSC) obtains the best photoelectric conversion efficiency (PCE) of 16.76% under AM 1.5 G illumination (100 mW cm{sup −2}) with enhanced J{sub sc} and V{sub oc} compared to CB-treated PSC.

Dissolution processes

International Nuclear Information System (INIS)

Silver, G.L.

1976-01-01

This review contains more than 100 observations and 224 references on the dissolution phenomenon. The dissolution processes are grouped into three categories: methods of aqueous attack, fusion methods, and miscellaneous observations on phenomena related to dissolution problems

In vivo in vitro correlations for a poorly soluble drug, danazol, using the flow-through dissolution method with biorelevant dissolution media

DEFF Research Database (Denmark)

Sunesen, Vibeke Hougaard; Pedersen, Betty Lomstein; Kristensen, Henning Gjelstrup

2005-01-01

The purpose of the study was to design dissolution tests that were able to distinguish between the behaviour of danazol under fasted and fed conditions, by using biorelevant media. In vitro dissolution of 100mg danazol capsules was performed using the flow-through dissolution method. Flow rates w...

Microbial contamination of single-and multiple-dose vials after opening in a pulmonary teaching hospital

Directory of Open Access Journals (Sweden)

Shadi Baniasadi

Full Text Available OBJECTIVES: Intravenous therapy is a complex procedure usually requiring the preparation of the medication in the clinical area before administration to the patient. Breaches in aseptic technique may result in microbial contaminations of vials which is a potential cause of different avoidable infections. We aimed to investigate the prevalence and pattern of microbial contamination of single- and multiple-dose vials in the largest pulmonary teaching hospital in Iran. METHODS: In a period of 2 months, opened single- and multiple-dose vials from different wards were sampled by a pharmacist. The name of the medication, ward, labeling of the vials, the date of opening, and storing temperature were recorded for each vial. Remained contents of each vial were cultured using appropriate bacterial and fungal growth media. RESULTS: Microbial contamination was identified in 11 of 205 (5.36% of vials. The highest contamination rate was 14.28% for vials used in interventional bronchoscopy unit. The most frequent contaminated medication was insulin. Gram-positive bacteria (81.82% were more significantly involved than gram-negative ones (9.09% and fungi (9.09%, with the highest frequency for Staphylococcus epidermidis . CONCLUSIONS: Our data demonstrate that repeated use of vials especially if basic sterility measures are disobeyed can cause microbial contamination of administered products to the patients. Infection preventionists are responsible to train health care workers regarding aseptic techniques and apply guidelines for aseptic handling of intravenous solutions.

Microbial contamination of single-and multiple-dose vials after opening in a pulmonary teaching hospital

Directory of Open Access Journals (Sweden)

Shadi Baniasadi

2013-02-01

Full Text Available OBJECTIVES: Intravenous therapy is a complex procedure usually requiring the preparation of the medication in the clinical area before administration to the patient. Breaches in aseptic technique may result in microbial contaminations of vials which is a potential cause of different avoidable infections. We aimed to investigate the prevalence and pattern of microbial contamination of single- and multiple-dose vials in the largest pulmonary teaching hospital in Iran. METHODS: In a period of 2 months, opened single- and multiple-dose vials from different wards were sampled by a pharmacist. The name of the medication, ward, labeling of the vials, the date of opening, and storing temperature were recorded for each vial. Remained contents of each vial were cultured using appropriate bacterial and fungal growth media. RESULTS: Microbial contamination was identified in 11 of 205 (5.36% of vials. The highest contamination rate was 14.28% for vials used in interventional bronchoscopy unit. The most frequent contaminated medication was insulin. Gram-positive bacteria (81.82% were more significantly involved than gram-negative ones (9.09% and fungi (9.09%, with the highest frequency for Staphylococcus epidermidis . CONCLUSIONS: Our data demonstrate that repeated use of vials especially if basic sterility measures are disobeyed can cause microbial contamination of administered products to the patients. Infection preventionists are responsible to train health care workers regarding aseptic techniques and apply guidelines for aseptic handling of intravenous solutions.

The adsorption of 99Tcsup(m) dimercaptosuccinic acid onto injection vials

International Nuclear Information System (INIS)

Millar, A.M.

1984-01-01

It is common practice to dispense radiopharmaceuticals into empty sterile vials for despatch to the departments where they are to be administered. It has been noted that on withdrawal of technetium-99m dimercaptosuccinic acid injections ( 99 Tcsup(m)-DMSA) which have been dispensed into such vials, the activities obtained are lower than expected. To explain this phenomenon, the adsorption of 99 Tcsup(m)-DMSA onto commercially available, empty, sterile vials has been investigated. The 99 Tcsup(m)-DMSA solutions were prepared using kits from two manufacturers and were tested in vials from two manufacturers and the original kit vials. Adsorption of 99 Tcsup(m) in one DMSA/vial combination after storage for 4 h was 49.6% (+- 4.5% S.E.M.), but typically, adsorption was approximately 12% after 4 h. Although rate of adsorption was found to vary with storage conditions, no conditions satisfactorily overcame the effect. In vials from one manufacturer, the 99 Tcsup(m) adsorption was predominantly on the glass, while in vials from the other, it was predominantly on the rubber stopper. It is concluded that the compatability between vials and radiopharmaceuticals must be investigated in the hospital radiopharmacy. (author)

Measurement of light emission in scintillation vials

International Nuclear Information System (INIS)

Duran Ramiro, M. Teresa; Garcia-Torano, Eduardo

2005-01-01

The efficiency and energy resolution of liquid scintillation counting (LSC) systems are strongly dependent on the optical characteristics of scintillators, vials, and reflectors. This article presents the results of measurements of the light-emission profile of scintillation vials. Two measurement techniques, autoradiographs and direct measurements with a photomultiplier tube, have been used to obtain light-emission distribution for standard vials of glass, etched glass and polyethylene. Results obtained with both techniques are in good agreement. For the first time, the effect of the meniscus in terms of light contribution has been numerically estimated. These results can help design LSC systems that are more efficient in terms of light collection

Development of dissolution test method for a telmisartan/amlodipine besylate combination using synchronous derivative spectrofluorimetry

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Panikumar Durga Anumolu

2014-04-01

Full Text Available The dissolution process is considered an important in vitro tool to evaluate product quality and drug release behavior. Single dissolution methods for the analysis of combined dosage forms are preferred to simplify quality control testing. The objective of the present work was to develop and validate a single dissolution test for a telmisartan (TEL and amlodipine besylate (AML combined tablet dosage form. The sink conditions, stability and specificity of both drugs in different dissolution media were tested to choose a discriminatory dissolution method, which uses an USP type-II apparatus with a paddle rotating at 75 rpm, with 900 mL of simulated gastric fluid (SGF without enzymes as the dissolution medium. This dissolution methodology provided good dissolution profiles for both TEL and AML and was able to discriminate changes in the composition and manufacturing process. To quantify both drugs simultaneously, a synchronous first derivative spectrofluorimetric method was developed and validated. Drug release was analyzed by a fluorimetric method at 458 nm and 675 nm for AML and TEL, respectively. The dissolution method was validated as per ICH guidance.

A maturation method of uranium content in resins with acid dissolution

International Nuclear Information System (INIS)

Liu Yang

2010-01-01

Acid dissolution method is that with intensively oxidation acid to decompose ion exchanging resins and dissolving U and Fe ion in water, then menstruate the U content by titration. Comparing with our current method of filtering wash, acid dissolution menstruation U can get more accurate result and take less time, use more simple device. (authors)

In-vial liquid-liquid microextraction-capillary electrophoresis method for the determination of phenolic acids in vegetable oils.

Science.gov (United States)

Abu Bakar, Nur Bahiyah; Makahleh, Ahmad; Saad, Bahruddin

2012-09-12

An in-vial liquid-liquid microextraction method was developed for the selective extraction of the phenolic acids (caffeic, gallic, cinnamic, ferulic, chlorogenic, syringic, vanillic, benzoic, p-hydroxybenzoic, 2,4-dihydroxybenzoic, o-coumaric, m-coumaric and p-coumaric) in vegetable oil samples. The optimised extraction conditions for 20 g sample were: volume of diluent (n-hexane), 2 mL; extractant, methanol: 5 mM sodium hydroxide (60:40; v/v); volume of extractant, 300 μL (twice); vortex, 1 min; centrifugation, 5 min. Recoveries for the studied phenolic acids were 80.1-119.5%. The simultaneous determination of the phenolic acid extracts was investigated by capillary electrophoresis (CE). Separations were carried out on a bare fused-silica capillary (50 μm i.d.× 40 cm length) involving 25 mM sodium tetraborate (pH 9.15) and 5% methanol as CE background electrolyte in the normal polarity mode, voltage of 30 kV, temperature of 25°C, injection time of 4s (50 mbar) and electropherograms were recorded at 200 nm. The phenolic acids were successfully separated in less than 10 min. The validated in-vial LLME-CE method was applied to the determination of phenolic acids in vegetable oil samples (extra virgin olive oil, virgin olive oil, pure olive oil, walnut oil and grapeseed oil). The developed method shows significant advantages over the current methods as lengthy evaporation step is not required. Copyright © 2012 Elsevier B.V. All rights reserved.

Analysis of pressurization of plutonium oxide storage vials during a postulated fire

Energy Technology Data Exchange (ETDEWEB)

Laurinat, J.; Kesterson, M.; Hensel, S.

2015-02-10

The documented safety analysis for the Savannah River Site evaluates the consequences of a postulated 1000 °C fire in a glovebox. The radiological dose consequences for a pressurized release of plutonium oxide powder during such a fire depend on the maximum pressure that is attained inside the oxide storage vial. To enable evaluation of the dose consequences, pressure transients and venting flow rates have been calculated for exposure of the storage vial to the fire. A standard B vial with a capacity of approximately 8 cc was selected for analysis. The analysis compares the pressurization rate from heating and evaporation of moisture adsorbed onto the plutonium oxide contents of the vial with the pressure loss due to venting of gas through the threaded connection between the vial cap and body. Tabulated results from the analysis include maximum pressures, maximum venting velocities, and cumulative vial volumes vented during the first 10 minutes of the fire transient. Results are obtained for various amounts of oxide in the vial, various amounts of adsorbed moisture, different vial orientations, and different surface fire exposures.

The effect of cool water pack preparation on vaccine vial temperatures in refrigerators.

Science.gov (United States)

Goldwood, Geneva; Diesburg, Steven

2018-01-02

Cool water packs are a useful alternative to ice packs for preventing unintentional freezing of vaccines during outreach in some situations. Current guidelines recommend the use of a separate refrigerator for cooling water packs from ambient temperatures to prevent possible heat degradation of adjacent vaccine vials. To investigate whether this additional equipment is necessary, we measured the temperatures that vaccine vials were exposed to when warm water packs were placed next to vials in a refrigerator. We then calculated the effect of repeated vial exposure to those temperatures on vaccine vial monitor status to estimate the impact to the vaccine. Vials were tested in a variety of configurations, varying the number and locations of vials and water packs in the refrigerator. The calculated average percentage life lost during a month of repeated warming ranged from 20.0% to 30.3% for a category 2 (least stable) vaccine vial monitor and from 3.8% to 6.0% for a category 7 (moderate stability) vaccine vial monitor, compared to 17.0% for category 2 vaccine vial monitors and 3.1% for category 7 vaccine vial monitors at a constant 5 °C. The number of vials, number of water packs, and locations of each impacted vial warming and therefore percentage life lost, but the vaccine vial monitor category had a higher impact on the average percentage life lost than any of the other parameters. The results suggest that damage to vaccines from repeated warming over the course of a month is not certain and that cooling water packs in a refrigerator where vaccines are being stored may be a useful practice if safe procedures are established. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Cluster endophthalmitis following multiple intravitreal bevacizumab injections from a single use vial

Directory of Open Access Journals (Sweden)

Perwez Khan

2016-01-01

Full Text Available The risk of endophthalmitis is always a concern when an intraocular procedure is performed. Intravitreal injection is a frequently used method for therapeutic management of many diseases, affecting the posterior segment of the eye. Hence, it is important to assess the risk of complications, especially endophthalmitis. Most studies conducted concentrate on risk assessment from single use from single drug vial. The present article reports the occurrence of cluster endophthalmitis following multiple intravitreal bevacizumab injections from a single vial. Intravitreal injection of bevacizumab was administered to eight eyes of eight patients. Administered dose was prepared from single 4-ml vial of bevacizumab and was injected in the eye, after patient preparation and under aseptic conditions. The procedure was repeated for the remaining patients, thereby imparting multiple pricks in the same vial. Four of the eight patients reported to the hospital on the 3rd day after injection with complaints of pain, watering, and diminution of vision. Two patients reported the following day with similar complaints. Two patients who did not report by the 4th day were contacted and recalled for an examination. All the patients were thoroughly examined using slit lamp biomicroscopy and indirect ophthalmoscopy. Six out of eight were clinically diagnosed to have endophthalmitis and were administered intravitreal antibiotics. The present report highlights possibility of microbial contamination of the drug vial or during compounding process. However, from the present incident, we are encouraged to stay vigilant and wary of contamination

Device for treating plastic counting vials containing radioactive liquids

International Nuclear Information System (INIS)

Neidhart, B.; Brindoepke, H.W.; Flocke, W.; Kringe, K.P.; Lippmann, C.H.

1985-01-01

The treatment consists of separating the radioactive contents of the counting vial from its plastic components. The apparatus consists of a device for continuously supplying the counting vials to be treated, a means for crushing the vials into chips of plastic and a facility by means of which the radioactive contents of the counting vial and the separated plastic chips are collected separately from one another. A stirring assembly with a motor-driven stirrer and an alignment device are also provided. The radioactive substances pass through a sieve while the plastic chips slide down the sieve chute and into another container. All the metal parts of the facility are of stainless steel. The plastic chips collected in the sieve holder are washed and, after drying, are removed as negligibly radioactive solids. The weakly radioactive wash liquid is separated and collected. (orig./PW)

Determination of low tritium activities, selection of suitable scintillator and measuring vials

International Nuclear Information System (INIS)

Tomasek, M.

1996-01-01

The scintillator cocktails tested were limited to scintillators highly miscible with water and included alkylnaphthalene-based scintillators exhibiting low toxicity and easy biodegradability. The following vials were tested: a vial of glass with reduced potassium content, a conventional polyethylene vial, and a teflon-coated polyethylene vial. Each combination was measured in triplicate: two samples of tritium-free water as the background and one sample with the standard tritium content. The best results were obtained when using a combination of the Ultima Gold LLT scintillator and the polyethylene vial. (M.D.) 2 tabs., 2 figs., 6 refs

Method for the analysis of triadimefon and ethofumesate from dislodgeable foliar residues on turfgrass by solid-phase extraction and in-vial elution.

Science.gov (United States)

Runes, H B; Jenkins, J J; Field, J A

1999-08-01

Triadimefon, a fungicide, and ethofumesate, an herbicide, are commonly applied to turfgrass in the Pacific Northwest, resulting in foliar residues. A simple and rapid method was developed to determine triadimefon and ethofumesate concentrations from dislodgeable foliar residues on turfgrass. Turfgrass samples were washed, and wash water containing surfactant (a 0.126% solution) was collected for residue analysis. This analytical method utilizes a 25 mm C(8) Empore disk and in-vial elution to quantitatively determine triadimefon and ethofumesate in 170 mL aqueous samples. The analytes were eluted by placing the disk in a 2 mL autosampler vial with 980 microL of ethyl acetate and 20 microL of 2-chlorolepidine, the internal standard, for analysis by GC/MS. The method quantitation limits are 0.29 microg/L for ethofumesate and 0.59 microg/L for triadimefon. The method detection limits are 0.047 microg/L and 0.29 microg/L for ethofumesate and triadimefon, respectively. Concentrations of triadimefon and ethofumesate from dislodgeable foliar residues from a field study are reported.

Determination of the external contamination and cross-contamination by cytotoxic drugs on the surfaces of vials available on the Swiss market.

Science.gov (United States)

Fleury-Souverain, Sandrine; Nussbaumer, Susanne; Mattiuzzo, Marc; Bonnabry, Pascal

2014-04-01

The external contamination and cross-contamination by cytotoxic drugs on the surface (outside and septum) of 133 vials from various manufacturers and available on the Swiss market were evaluated. All of the tested vials contained one of the following active ingredients: cyclophosphamide, cytarabine, doxorubicin, epirubicin, etoposide phosphate, gemcitabine, ifosfamide, irinotecan, methotrexate or vincristine. The validated wiping liquid chromatography-mass spectrometry method used in this study allowed for the simultaneous determination of these 10 cytotoxic drugs in less than 30 min. External contamination by cytotoxic drugs was detected on 63% of tested vials (outside and septum). The highest contamination level was observed on etoposide phosphate vials with 1896.66 ng of active ingredient on the outside of the vial. Approximately 20% of the contaminated vials had greater than 10 ng of cytotoxic drugs. Chemical contamination on the septum was detected on 38% of the vials. No contamination or very low levels of cytotoxic drugs, less than 1 ng per vial, were detected on the vials protected by plastic shrink-wrap. Traces of cytotoxic drugs different from the active ingredient were detected on 35% of the tested vials. Handling cytotoxic vials with gloves and having a procedure for the decontamination of vials are of the utmost importance for reducing exposure to cytotoxic drugs. Moreover, manufacturers must improve their procedures to provide products free from any contamination.

Novel silk fibroin films prepared by formic acid/hydroxyapatite dissolution method

International Nuclear Information System (INIS)

Ming, Jinfa; Liu, Zhi; Bie, Shiyu; Zhang, Feng; Zuo, Baoqi

2014-01-01

Bombyx mori silk fibroin from the silkworm was firstly found to be soluble in formic acid/hydroxyapatite system. The rheological behavior of silk fibroin solution was significantly influenced by HAp contents in dissolved solution. At the same time, silk fibroin nanofibers were observed in dissolved solution with 103.6 ± 20.4 nm in diameter. Moreover, the structure behavior of SF films prepared by formic acid/hydroxyapatite dissolution method was examined. The secondary structure of silk fibroin films was attributed to silk II structure (β-sheet), indicating that the hydroxyapatite contents in dissolved solution were not significantly affected by the structure of silk fibroin. The X-ray diffraction results exhibited obviously hydroxyapatite crystalline nature existing in silk fibroin films; however, when the hydroxyapatite content was 5.0 wt.% in dissolved solution, some hydroxyapatite crystals were converted to calcium hydrogen phosphate dehydrate in silk fibroin dissolution process. This result was also confirmed by Fourier transform infrared analysis and DSC measurement. In addition, silk fibroin films prepared by this dissolution method had higher breaking strength and extension at break. Based on these analyses, an understanding of novel SF dissolution method may provide an additional tool for designing and synthesizing advanced materials with more complex structures, which should be helpful in different fields, including biomaterial applications. - Highlights: • SF fibers were firstly successfully dissolved in FA/HAp solution. • The rheological behavior of SF solution was significantly influenced by HAp contents. • SF nanofibrils were observed in FA/HAp solution with 103.6 ± 20.4 nm in diameter. • SF films prepared by FA/HAp dissolution method had higher mechanical properties

Novel silk fibroin films prepared by formic acid/hydroxyapatite dissolution method

Energy Technology Data Exchange (ETDEWEB)

Ming, Jinfa, E-mail: jinfa.ming@gmail.com [National Engineering Laboratory for Modern Silk, Soochow University, Suzhou 215123 (China); College of Textile and Clothing Engineering, Soochow University, Suzhou 215021 (China); Liu, Zhi; Bie, Shiyu [National Engineering Laboratory for Modern Silk, Soochow University, Suzhou 215123 (China); College of Textile and Clothing Engineering, Soochow University, Suzhou 215021 (China); Zhang, Feng [Jiangsu Province Key Laboratory of Stem Cell Research, Medical College, Soochow University, Suzhou 215006 (China); Zuo, Baoqi, E-mail: bqzuo@suda.edu.cn [National Engineering Laboratory for Modern Silk, Soochow University, Suzhou 215123 (China); College of Textile and Clothing Engineering, Soochow University, Suzhou 215021 (China)

2014-04-01

Bombyx mori silk fibroin from the silkworm was firstly found to be soluble in formic acid/hydroxyapatite system. The rheological behavior of silk fibroin solution was significantly influenced by HAp contents in dissolved solution. At the same time, silk fibroin nanofibers were observed in dissolved solution with 103.6 ± 20.4 nm in diameter. Moreover, the structure behavior of SF films prepared by formic acid/hydroxyapatite dissolution method was examined. The secondary structure of silk fibroin films was attributed to silk II structure (β-sheet), indicating that the hydroxyapatite contents in dissolved solution were not significantly affected by the structure of silk fibroin. The X-ray diffraction results exhibited obviously hydroxyapatite crystalline nature existing in silk fibroin films; however, when the hydroxyapatite content was 5.0 wt.% in dissolved solution, some hydroxyapatite crystals were converted to calcium hydrogen phosphate dehydrate in silk fibroin dissolution process. This result was also confirmed by Fourier transform infrared analysis and DSC measurement. In addition, silk fibroin films prepared by this dissolution method had higher breaking strength and extension at break. Based on these analyses, an understanding of novel SF dissolution method may provide an additional tool for designing and synthesizing advanced materials with more complex structures, which should be helpful in different fields, including biomaterial applications. - Highlights: • SF fibers were firstly successfully dissolved in FA/HAp solution. • The rheological behavior of SF solution was significantly influenced by HAp contents. • SF nanofibrils were observed in FA/HAp solution with 103.6 ± 20.4 nm in diameter. • SF films prepared by FA/HAp dissolution method had higher mechanical properties.

Optimizing human semen cryopreservation by reducing test vial volume and repetitive test vial sampling

DEFF Research Database (Denmark)

Jensen, Christian F S; Ohl, Dana A; Parker, Walter R

2015-01-01

OBJECTIVE: To investigate optimal test vial (TV) volume, utility and reliability of TVs, intermediate temperature exposure (-88°C to -93°C) before cryostorage, cryostorage in nitrogen vapor (VN2) and liquid nitrogen (LN2), and long-term stability of VN2 cryostorage of human semen. DESIGN......: Prospective clinical laboratory study. SETTING: University assisted reproductive technology (ART) laboratory. PATIENT(S): A total of 594 patients undergoing semen analysis and cryopreservation. INTERVENTION(S): Semen analysis, cryopreservation with different intermediate steps and in different volumes (50......-1,000 μL), and long-term storage in LN2 or VN2. MAIN OUTCOME MEASURE(S): Optimal TV volume, prediction of cryosurvival (CS) in ART procedure vials (ARTVs) with pre-freeze semen parameters and TV CS, post-thaw motility after two- or three-step semen cryopreservation and cryostorage in VN2 and LN2. RESULT...

Calibration of the NPL secondary standard radionuclide calibrator for the new 10R Schott, Type 1+ vials

International Nuclear Information System (INIS)

Baker, M.

2005-01-01

For many years, P6 vials have been used for the distribution of a wide range of diagnostic and therapeutic radioactive solutions. The activity measurements were performed in this geometry and, in time, the UK calibration system for nuclear medicine was based on this container as a standard. However, one major supplier of radiopharmaceuticals has replaced the P6 vial with the 10R Type 1+ Schott vial. As the dimensions of the new vial are different from those of the P6 vial and the responses of radionuclide calibrators are known to be container dependent, the need for re-calibration became apparent. Preliminary measurements made on some typical radionuclide calibrators for 125 I solution indicated a difference in response of about 10% between the two vials. The master ionisation chamber of the NPL secondary standard radionuclide calibrator has been re-calibrated and new calibration factors and volume correction factors for 10R Schott vials have been derived for the relevant medical radionuclides. The standard holder was also modified to accommodate the new larger vial. The complete list of factors and the method used to determine them is presented in this paper. The availability of these new factors will improve the quality of activity measurements in nuclear medicine, as calibration services can now be provided by NPL for the new container. These factors can also be employed for all commercial NPL secondary standard radionuclide calibrators (now known as the NPL-CRC and previously as the 671 or ISOCAL IV)

Economic and microbiologic evaluation of single-dose vial extension for hazardous drugs.

Science.gov (United States)

Rowe, Erinn C; Savage, Scott W; Rutala, William A; Weber, David J; Gergen-Teague, Maria; Eckel, Stephen F

2012-07-01

The update of US Pharmacopeia Chapter in 2008 included guidelines stating that single-dose vials (SDVs) opened and maintained in an International Organization for Standardization Class 5 environment can be used for up to 6 hours after initial puncture. A study was conducted to evaluate the cost of discarding vials after 6 hours and to further test sterility of vials beyond this time point, subsequently defined as the beyond-use date (BUD). Financial determination of SDV waste included 2 months of retrospective review of all doses prescribed. Additionally, actual waste log data were collected. Active and control vials (prepared using sterilized trypticase soy broth) were recovered, instead of discarded, at the defined 6-hour BUD. The institution-specific waste of 19 selected SDV medications discarded at 6 hours was calculated at $766,000 annually, and tracking waste logs for these same medications was recorded at $770,000 annually. Microbiologic testing of vial extension beyond 6 hours showed that 11 (1.86%) of 592 samples had one colony-forming unit on one of two plates. Positive plates were negative at subsequent time points, and all positives were single isolates most likely introduced during the plating process. The cost of discarding vials at 6 hours was significant for hazardous medications in a large academic medical center. On the basis of microbiologic data, vial BUD extension demonstrated a contamination frequency of 1.86%, which likely represented exogenous contamination; vial BUD extension for the tested drugs showed no growth at subsequent time points and could provide an annual cost savings of more than $600,000.

In vitro release of ketoprofen suppositories using the USP basket and the flow-through cell dissolution methods.

Science.gov (United States)

Medina, José Raúl; Padilla, Adrián Roberto; Hurtado, Marcela; Cortés, Alma Rosa; Domínguez-Ramírez, Adriana Miriam

2014-05-01

In order to study the release characteristics of ketoprofen suppositories under the hydrodynamic environment generated by USP Apparatus 1 and 4, the dissolution profiles of the Mexican reference product (100 mg) were determined. Phosphate buffer pH 8 and 1% sodium lauryl sulfate (SLS) aqueous solutions were proved as dissolution mediums. Baskets were rotated at 100 rpm with USP Apparatus 1 and different flow rates from 16-32 mL/min with USP Apparatus 4 were used. Drug samples were taken and quantified during 60 min by UV analysis at 260 nm. Mean dissolution time (MDT) and dissolution efficiency (DE) were calculated by model-independent methods. Data were also fitted to several kinetic models. Poor dissolution was found in both dissolution mediums when USP basket method was used ( 0.99). The results suggest the need to establish an adequate dissolution method to evaluate the release kinetics of ketoprofen from suppositories.

pH-metric solubility. 3. Dissolution titration template method for solubility determination.

Science.gov (United States)

Avdeef, A; Berger, C M

2001-12-01

The main objective of this study was to develop an effective potentiometric saturation titration protocol for determining the aqueous intrinsic solubility and the solubility-pH profile of ionizable molecules, with the specific aim of overcoming incomplete dissolution conditions, while attempting to shorten the data collection time. A modern theory of dissolution kinetics (an extension of the Noyes-Whitney approach) was applied to acid-base titration experiments. A thermodynamic method was developed, based on a three-component model, to calculate interfacial, diffusion-layer, and bulk-water reactant concentrations in saturated solutions of ionizable compounds perturbed by additions of acid/base titrant, leading to partial dissolution of the solid material. Ten commercial drugs (cimetidine, diltiazem hydrochloride, enalapril maleate, metoprolol tartrate, nadolol, propoxyphene hydrochloride, quinine hydrochloride, terfenadine, trovafloxacin mesylate, and benzoic acid) were chosen to illustrate the new titration methodology. It was shown that the new method is about 10 times faster in determining equilibrium solubility constants, compared to the traditional saturation shake-flask methods.

The study of vial and cocktail for tritium radioactivity analysis of rain water by liquid scintillation counter

International Nuclear Information System (INIS)

Noh, Sung Jin; Kim, Hyo Jin; Kim, Hyun; Lee, Man Woo; Jeong, Dong Hyeok; Yang, Kwang Mo; Kang, Yeong Rok; Nam, Sang Hee

2015-01-01

Even though the current method for tritium (3H) analysis is routine, for the case of the low level of tritium in the environment, special conditions have to be fulfilled in order to obtain accurate and reliable tritium measurements. There are very little comparative data concerning commercial scintillating cocktails. The best cocktails for measuring tritium are those based on benzene derived solvent, and the worse cocktails are those which have complex chemical composition or contain too small concentration of scintillators. The aim of study was to investigate various vials and cocktails by comparison with the combination of few different scintillation cocktails and vials in our routine measurements according to count, efficiency, and the figure of merit (FOM). The comparison of three types of vials with scintillation cocktails for tritium activity analysis of rain water shows that glass vials have higher count rates and HiSafe 3 cocktails have lower FOM

Inventarios viales y categorización de la red vial en estudios de Ingeniería de Tránsito y Transporte

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Julián Rodrigo Quintero

2011-03-01

Full Text Available Se presentan las principales consideraciones y los aspectos técnicos fundamentales de la elaboración de Inventarios Viales y la Categorización de la Red Vial, aplicadas a la realización de estudios de ingeniería de tránsito y transporte. Se exponen los aspectos generales relacionados con la elaboración de los inventarios de infraestructura vial, de señalización y dispositivos de control, de estacionamientos, de paraderos y de rutas de transporte público colectivo urbano de pasajeros, como una herramienta práctica para complementar los procedimientos de campo y optimizar los procesos y análisis de resultados orientados a identificar, caracterizar y cuantificar las variables relacionadas con el desarrollo del fenómeno del tránsito y la actividad del transporte.

Comprehensive validation scheme for in situ fiber optics dissolution method for pharmaceutical drug product testing.

Science.gov (United States)

Mirza, Tahseen; Liu, Qian Julie; Vivilecchia, Richard; Joshi, Yatindra

2009-03-01

There has been a growing interest during the past decade in the use of fiber optics dissolution testing. Use of this novel technology is mainly confined to research and development laboratories. It has not yet emerged as a tool for end product release testing despite its ability to generate in situ results and efficiency improvement. One potential reason may be the lack of clear validation guidelines that can be applied for the assessment of suitability of fiber optics. This article describes a comprehensive validation scheme and development of a reliable, robust, reproducible and cost-effective dissolution test using fiber optics technology. The test was successfully applied for characterizing the dissolution behavior of a 40-mg immediate-release tablet dosage form that is under development at Novartis Pharmaceuticals, East Hanover, New Jersey. The method was validated for the following parameters: linearity, precision, accuracy, specificity, and robustness. In particular, robustness was evaluated in terms of probe sampling depth and probe orientation. The in situ fiber optic method was found to be comparable to the existing manual sampling dissolution method. Finally, the fiber optic dissolution test was successfully performed by different operators on different days, to further enhance the validity of the method. The results demonstrate that the fiber optics technology can be successfully validated for end product dissolution/release testing. (c) 2008 Wiley-Liss, Inc. and the American Pharmacists Association

Inventarios viales y categorización de la red vial en estudios de Ingeniería de Tránsito y Transporte

Directory of Open Access Journals (Sweden)

Julián Rodrigo Quintero

2011-11-01

Full Text Available Se presentan las principales consideraciones y los aspectos técnicos fundamentales de la elaboración de Inventarios Viales y la Categorización de la Red Vial, aplicadas a la realización de estudios de ingeniería de tránsito y transporte. Se exponen los aspectos generales relacionados con la elaboración de los inventarios de infraestructura vial, de señalización y dispositivos de control, de estacionamientos, de paraderos y de rutas de transporte público colectivo urbano de pasajeros, como una herramienta práctica para complementar los procedimientos de campo y optimizar los procesos y análisis de resultados orientados a identificar, caracterizar y cuantificar las variables relacionadas con el desarrollo del fenómeno del tránsito y la actividad del transporte.

Development of simulation code for MOX dissolution using silver-mediated electrochemical method (Contract research)

Energy Technology Data Exchange (ETDEWEB)

Kida, Takashi; Umeda, Miki; Sugikawa, Susumu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2003-03-01

MOX dissolution using silver-mediated electrochemical method will be employed for the preparation of plutonium nitrate solution in the criticality safety experiments in the Nuclear Fuel Cycle Safety Engineering Research Facility (NUCEF). A simulation code for the MOX dissolution has been developed for the operating support. The present report describes the outline of the simulation code, a comparison with the experimental data and a parameter study on the MOX dissolution. The principle of this code is based on the Zundelevich's model for PuO{sub 2} dissolution using Ag(II). The influence of nitrous acid on the material balance of Ag(II) is taken into consideration and the surface area of MOX powder is evaluated by particle size distribution in this model. The comparison with experimental data was carried out to confirm the validity of this model. It was confirmed that the behavior of MOX dissolution could adequately be simulated using an appropriate MOX dissolution rate constant. It was found from the result of parameter studies that MOX particle size was major governing factor on the dissolution rate. (author)

U-Pb dating by zircon dissolution method using chemical abrasion

Energy Technology Data Exchange (ETDEWEB)

Takehara, Lucy, E-mail: lucytakehara@gmail.com.br [Servico Geologico do Brasil (CPRM), Brasilia, DF (Brazil); Chemale Junior, Farid [Universidade de Brasilia (UnB), Brasilia, DF (Brazil). Inst. de Geociencias. Lab. de Geocronologia; Hartmann, Leo A. [Universidade Federal do Rio Grande do Sul (UFRS), Porto Alegre, RS (Brazil). Inst. de Geociencias; Dussin, Ivo A.; Kawashita, Koji [Universidade de Sao Paulo (USP), SP, (Brazil). Centro de Pesquisa Geocronologicas

2012-06-15

Chemical abrasion was carried out on zircons grains of the Temora II standard for U-Pb dating prior to analyses using in situ Laser Ablation-Multi Collector Ion Coupled Plasma Mass Spectrometer (LA-ICPMS) followed by the Isotope Dissolution Thermal Ionization Mass Spectrometer (ID-TIMS) method. The proposed methodology was herein applied in order to reduce primarily the effects of secondary Pb loss, the presence of common lead and/or silicate impurities. Nine Temora II zircon grains were analyzed by the laser ablation method yielding an age of 418.3 +- 4.3 Ma. Zircon grains of a same population were separated for chemical abrasion before dissolution and mass spectrometry analyses. Six fractions of them were separated for isotope dissolution using {sup 235}U-{sup 205}Pb mixed spike after we have checked and assured the laboratory conditions of low blank values for total Pb of less than 2 pg/g. The obtained U-Pb zircon age by the ID-TIMS method was 415.7 +- 1.8 Ma (error 0.43 %) based on four successful determinations. The results are consistent with the published ages for the Temora diorite (Temora I - 416.75 +- 1.3 Ma; Temora II - 416.78 +- 0.33 Ma) and established as 416 +- 0.33 Ma. The technique is thus recommended for high precision U-Pb zircon analyses (error < 1 %), mainly for high resolution stratigraphic studies of Phanerozoic sequences. (author)

The application of dual-electrode through vial impedance spectroscopy for the determination of ice interface temperatures, primary drying rate and vial heat transfer coefficient in lyophilization process development.

Science.gov (United States)

Smith, Geoff; Jeeraruangrattana, Yowwares; Ermolina, Irina

2018-06-22

Through vial impedance spectroscopy (TVIS) is a product non-invasive process analytical technology which exploits the frequency dependence of the complex impedance spectrum of a composite object (i.e. the freeze-drying vial and its contents) in order to track the progression of the freeze-drying cycle. This work demonstrates the use of a dual electrode system, attached to the external surface of a type I glass tubing vial (nominal capacity 10 mL) in the prediction of (i) the ice interface temperatures at the sublimation front and at the base of the vial, and (ii) the primary drying rate. A value for the heat transfer coefficient (for a chamber pressure of 270 µbar) was then calculated from these parameters and shown to be comparable to that published by Tchessalov[1]. Copyright © 2018. Published by Elsevier B.V.

Valoraciones sobre la gestión del sistema de seguridad vial en Cuba.

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Tania Ivón Sosa Ibarra

2015-12-01

Full Text Available El presente trabajo tiene como objetivo valorar con enfoque crítico el cumplimiento de la agenda del Observatorio Iberoamericano para la Seguridad Vial (OISEVI que evidencie los aciertos y desaciertos en esta actividad, se analiza en la literatura los enfoques de los autores Tony Bliss y Jeanne Breen que enfatizan en la concepción de sistema no solo a la seguridad vial sino también a la gestión de esta como sistema y se realiza una aplicación de los aspectos de la encuesta del OISEVI a la gestión de la seguridad vial en Cuba por el grupo de asesores de la Comisión Nacional de seguridad vial, pertenecientes a la Universidad de Sancti Spíritus, que durante los últimos años estudian esta problemática, detallando los argumentos que conciben para otorgar los valores en las respuestas al cuestionario. Con esta encuesta se obtiene una primera aproximación del estado de la gestión de la seguridad vial en el país, y se arriban a valoraciones acerca de cómo se encuentra Cuba respecto a los lineamientos básicos y generales que hacen exitosa a la gestión en seguridad vial, basada en los cinco pilares del Plan Mundial para el Decenio de Acción para la Seguridad Vial 2011-2020.

Development and application of a biorelevant dissolution method using USP apparatus 4 in early phase formulation development.

Science.gov (United States)

Fang, Jiang B; Robertson, Vivian K; Rawat, Archana; Flick, Tawnya; Tang, Zhe J; Cauchon, Nina S; McElvain, James S

2010-10-04

Dissolution testing is frequently used to determine the rate and extent at which a drug is released from a dosage form, and it plays many important roles throughout drug product development. However, the traditional dissolution approach often emphasizes its application in quality control testing and usually strives to obtain 100% drug release. As a result, dissolution methods are not necessarily biorelevant and meaningful application of traditional dissolution methods in the early phases of drug product development can be very limited. This article will describe the development of a biorelevant in vitro dissolution method using USP apparatus 4, biorelevant media, and real-time online UV analysis. Several case studies in the areas of formulation selection, lot-to-lot variability, and food effect will be presented to demonstrate the application of this method in early phase formulation development. This biorelevant dissolution method using USP apparatus 4 provides a valuable tool to predict certain aspects of the in vivo drug release. It can be used to facilitate the formulation development/selection for pharmacokinetic (PK) and clinical studies. It may also potentially be used to minimize the number of PK studies, and to aid in the design of more efficient PK and clinical studies.

Comparative evaluation of methods to quantify dissolution of nanomaterials

DEFF Research Database (Denmark)

Hartmann, Nanna B.; Kruse, Susanne; Baun, Anders

2015-01-01

Effects and behaviour of nanomaterials in the environment depends on the materials' specific physical and chemical properties and for certain nanomaterials (e.g., Ag, ZnO and CuO) aqueous solubility is of outmost importance. The solubility of metals salts is normally described as a maximum...... dissolved concentration or by the solubility constant (Ksp). For nanomaterials it is essential to also assess solubility kinetics as nanomaterials will often not dissolve instantaneously upon contact with artificial aqueous media or natural waters. Dissolution kinetics will thereby influence their short...... and long-term environmental fate as well as laboratory test results. This highlights the need to evaluate and improve the reliability of methods applied to assess the solubility kinetics of nanomaterials. Based on existing OECD guidelines and guidance documents on aqueous dissolution of metals and metal...

Container/Closure Integrity Testing and the Identification of a Suitable Vial/Stopper Combination for Low-Temperature Storage at -80 {degrees}C.

Science.gov (United States)

Zuleger, Brigitte; Werner, Uwe; Kort, Alexander; Glowienka, Rene; Wehnes, Engelbert; Duncan, Derek

2012-01-01

It was recently found that after storage of a live viral vaccine at -80 °C in glass vials closed with rubber stoppers, a phenomenon was revealed which had not been observed before with other viral products stored at -20 °C: overpressure in the vials. As this phenomenon poses a serious safety problem for medical personnel as well as for the product itself, an investigation was initiated to identify the root cause of the overpressure. After exclusion of possible root causes (differences in air temperature or atmospheric air pressure during filling and quality control testing, outgassing from the formulation buffer) the remaining hypothesis involved a possible container closure integrity issue at low temperature. The glass transition temperatures (T(g)) of many rubber stopper formulations are in the range -55 to -70 °C. At storage temperatures below T(g), the rubber stopper loses its elastic properties and there is a risk that the seal integrity of the vial could be compromised. Loss of seal integrity of the vials near storage temperatures of -80 °C would result in an ingress of cold dense gas into the vial headspace. After removal of the vials from storage at -80 °C, the rubber stoppers could regain their elastic properties and the vials would quickly reseal, thereby trapping the ingressed gas, which leads to overpressure in the vial headspace. Nondestructive laser-based headspace analysis was used to investigate the maintenance of container closure integrity as a function of the filling and capping/crimping process, storage and transport conditions, and vial/stopper designs. This analytical method is based on frequency modulation spectroscopy (FMS) and can be used for noninvasive headspace measurements of headspace pressure and headspace gas composition. Changes in the vial headspace composition and/or pressure are a clear marker for vials that have lost container closure integrity. After storage of a live viral vaccine at -80 °C in glass vials closed with

Impact of changing the measles vaccine vial size on Niger's vaccine supply chain: a computational model

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Kenea Hailu

2011-06-01

Full Text Available Abstract Background Many countries, such as Niger, are considering changing their vaccine vial size presentation and may want to evaluate the subsequent impact on their supply chains, the series of steps required to get vaccines from their manufacturers to patients. The measles vaccine is particularly important in Niger, a country prone to measles outbreaks. Methods We developed a detailed discrete event simulation model of the vaccine supply chain representing every vaccine, storage location, refrigerator, freezer, and transport device (e.g., cold trucks, 4 × 4 trucks, and vaccine carriers in the Niger Expanded Programme on Immunization (EPI. Experiments simulated the impact of replacing the 10-dose measles vial size with 5-dose, 2-dose and 1-dose vial sizes. Results Switching from the 10-dose to the 5-dose, 2-dose and 1-dose vial sizes decreased the average availability of EPI vaccines for arriving patients from 83% to 82%, 81% and 78%, respectively for a 100% target population size. The switches also changed transport vehicle's utilization from a mean of 58% (range: 4-164% to means of 59% (range: 4-164%, 62% (range: 4-175%, and 67% (range: 5-192%, respectively, between the regional and district stores, and from a mean of 160% (range: 83-300% to means of 161% (range: 82-322%, 175% (range: 78-344%, and 198% (range: 88-402%, respectively, between the district to integrated health centres (IHC. The switch also changed district level storage utilization from a mean of 65% to means of 64%, 66% and 68% (range for all scenarios: 3-100%. Finally, accounting for vaccine administration, wastage, and disposal, replacing the 10-dose vial with the 5 or 1-dose vials would increase the cost per immunized patient from $0.47US to $0.71US and $1.26US, respectively. Conclusions The switch from the 10-dose measles vaccines to smaller vial sizes could overwhelm the capacities of many storage facilities and transport vehicles as well as increase the cost per

Mathematical methods for quantification and comparison of dissolution testing data

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Edina Vranić

2002-02-01

Full Text Available In recent years, drug release/dissolution from solid dosage forms has been the subject of intense and profitable scientific developments. Whenever a new solid dosage form is developed or produced, it is necessary to ensure that drug dissolutionoccurs in an appropriate manner. The pharmaceutical industry and the registration authorities do focus, nowadays, on drug dissolution studies. The quantitative analysis of the values obtained in dissolution/release tests is easier when mathematicalformulas that express the dissolution results as a function of some of the dosage forms characteristics are used. This work discusses the analysis of data obtained for dissolution profiles under different media pH conditions using mathematical methodsof analysis described by Moore and Flanner. These authors have described difference factor (f1 and similarity factor (f2, which can be used to characterise drug dissolution/release profiles. In this work we have used these formulas for evaluation of dissolution profiles of the conventional tablets in different pH of dissolution medium (range of physiological variations.

Red Vial de Nicaragua (Optimización y Mantenimiento

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Wilfredo Martínez

2013-06-01

Full Text Available La red vial es un patrimonio nacional, el cual es necesario: proteger, conservar, aumentar y mejorar; para apoyar eldesarrollo socioeconómico de nuestro país. La actividad de mantenimiento, constituye un factor determinante quegarantiza la operación satisfactoria del transporte durante la vida útil de los caminos; en sus diferentes modalidades. La ausencia de un mantenimiento preventivo y de un mantenimiento correctivo tardío, conduce a que la inversiónrealizada sufra una depreciación más acelerada, acortando su vida útil; obteniendo un grado de aprovechamientomenor que se traduce en una disminución de los beneficios estimados, ya que la rentabilidad no podrá ser óptima aldescuidar esta función. “Con frecuencia, los costos operativos de los vehículos, excederán los costos de losdepartamentos viales por un factor de 10 o màs, especialmente en carreteras de gran volumen de trànsito”.(Zaniewski, 1989. Por lo tanto, los costos (economía de los usuarios deben ser tomados en cuenta al momento deproyectar la construcción de una carretera. Por tal razón el Gobierno de Nicaragua, en conjunto con lasinstituciones correspondientes, han asumido un rol prioritario en la ejecución y mantenimiento de la red vial. Esteensayo pretende aportar elementos cuantitativos y cualitativos, para el análisis y mejoramiento de la Red Vial.

Development and validation of a dissolution method using HPLC for diclofenac potassium in oral suspension

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Alexandre Machado Rubim

2014-04-01

Full Text Available The present study describes the development and validation of an in vitro dissolution method for evaluation to release diclofenac potassium in oral suspension. The dissolution test was developed and validated according to international guidelines. Parameters like linearity, specificity, precision and accuracy were evaluated, as well as the influence of rotation speed and surfactant concentration on the medium. After selecting the best conditions, the method was validated using apparatus 2 (paddle, 50-rpm rotation speed, 900 mL of water with 0.3% sodium lauryl sulfate (SLS as dissolution medium at 37.0 ± 0.5°C. Samples were analyzed using the HPLC-UV (PDA method. The results obtained were satisfactory for the parameters evaluated. The method developed may be useful in routine quality control for pharmaceutical industries that produce oral suspensions containing diclofenac potassium.

The pharmaceutical vial capping process: Container closure systems, capping equipment, regulatory framework, and seal quality tests.

Science.gov (United States)

Mathaes, Roman; Mahler, Hanns-Christian; Buettiker, Jean-Pierre; Roehl, Holger; Lam, Philippe; Brown, Helen; Luemkemann, Joerg; Adler, Michael; Huwyler, Joerg; Streubel, Alexander; Mohl, Silke

2016-02-01

Parenteral drug products are protected by appropriate primary packaging to protect against environmental factors, including potential microbial contamination during shelf life duration. The most commonly used CCS configuration for parenteral drug products is the glass vial, sealed with a rubber stopper and an aluminum crimp cap. In combination with an adequately designed and controlled aseptic fill/finish processes, a well-designed and characterized capping process is indispensable to ensure product quality and integrity and to minimize rejections during the manufacturing process. In this review, the health authority requirements and expectations related to container closure system quality and container closure integrity are summarized. The pharmaceutical vial, the rubber stopper, and the crimp cap are described. Different capping techniques are critically compared: The most common capping equipment with a rotating capping plate produces the lowest amount of particle. The strength and challenges of methods to control the capping process are discussed. The residual seal force method can characterize the capping process independent of the used capping equipment or CCS. We analyze the root causes of several cosmetic defects associated with the vial capping process. Copyright © 2015 Elsevier B.V. All rights reserved.

A new method for alkaline dissolution of uranium metal foil

International Nuclear Information System (INIS)

Mondino, A.V.; Wilkinson, M.V.; Manzini, A.C.

2001-01-01

In order to develop a production process of 99 Mo by fission of low-enriched uranium, the first purification step, which consists of dissolution of a uranium metal foil target, was studied. It was found that alkaline NaClO gave good results, reaching the dissolution of up to 300 μm of uranium foil. The different conditions for the dissolution were studied and the optimum ones were found. The influence of NaClO and NaOH concentration, temperature, dissolving solution volume per unit of surface and dissolution time were investigated. During this step, a gas identified as H 2 , was generated, and a precipitate characterized as Na 2 U 2 O 7 was observed. A stoichiometric reaction for this uranium dissolution is proposed. (author)

A reliable technique for transfer of radioactivity filled vial from transport container to the processing station

International Nuclear Information System (INIS)

Kothalkar, Chetan; Dey, A.C.

2005-01-01

In Technetium Column Generator Production Facility (TCGPF project) of BRIT, a facility for unloading vial containing radioactive liquid sodium molybdate- 99 Mo solution from the transport cask into the processing station and unsealing the vial to transfer the liquid to a storage bottle has been developed. This is specifically conceptualized for safe handling of radioactivity and minimizing the radiation dose exposure to the personnel working at the time of transferring the radioactivity from the transport cask to a place for further processing. The facility, designed to handle around 1850 GBq activity, has two cells enclosed in 102mm thick lead wall and connected by a gravity actuated trolley conveyor. The first cell handles the transport cask carrying the vial-containing radioactivity, which houses two types of vial lifting gadgets assisted by manually operatable tongs. Gadgets use compressed air. In an experiment, it is found that the HDPE vial lifting gadget using suction cup continue to function up to 30-40 minutes after power failure. The experience shows that gadget using 3-point radial gripper to lift the glass vial will remain in grab position, even if the compressed air supply stops. In this facility the dose receivable, while handling radioactivity by the operator, is likely to be negligibly small (approx. 3.15 x 10 -4 mSv per year at the rate four glass vials/week and 2.25 x 10 -4 mSv per year considering at the rate 1 vial/week for HOPE vial transfer). (author)

The effect of vial type and cocktail quantity on tritium measurement in LSC

International Nuclear Information System (INIS)

Chen Zhilin; Xing Shixiong; Wang Heyi; Chang Ruimin; Wu Guanyin; Zhou Yinhang

2010-01-01

The effect of sample vial type and cocktail quantity on tritium measurement in liquid scintillation counting is studied in this paper. With both high and low level tritium samples, glass vials allow higher counting rates than plastic vials do. We also present detailed analysis of the way to obtain the optimal counting condition by dispensing different quantity of cocktail into sample vials. Results indicate that the optimal counting condition has little relationship with tritium concentration in the sample. The main factor which influences the counting is the quantity of cocktail added into samples. Figure of merit is employed to access the results, which increases as the quantity of cocktail increasing. But when the ratio of cocktail and sample reaches 2.0, increase of ratio makes little contribution to the counts, and the disintegrations per minute comes nearly to be a constant.

Improving Heat Transfer at the Bottom of Vials for Consistent Freeze Drying with Unidirectional Structured Ice.

Science.gov (United States)

Rosa, Mónica; Tiago, João M; Singh, Satish K; Geraldes, Vítor; Rodrigues, Miguel A

2016-10-01

The quality of lyophilized products is dependent of the ice structure formed during the freezing step. Herein, we evaluate the importance of the air gap at the bottom of lyophilization vials for consistent nucleation, ice structure, and cake appearance. The bottom of lyophilization vials was modified by attaching a rectified aluminum disc with an adhesive material. Freezing was studied for normal and converted vials, with different volumes of solution, varying initial solution temperature (from 5°C to 20°C) and shelf temperature (from -20°C to -40°C). The impact of the air gap on the overall heat transfer was interpreted with the assistance of a computational fluid dynamics model. Converted vials caused nucleation at the bottom and decreased the nucleation time up to one order of magnitude. The formation of ice crystals unidirectionally structured from bottom to top lead to a honeycomb-structured cake after lyophilization of a solution with 4% mannitol. The primary drying time was reduced by approximately 35%. Converted vials that were frozen radially instead of bottom-up showed similar improvements compared with normal vials but very poor cake quality. Overall, the curvature of the bottom of glass vials presents a considerable threat to consistency by delaying nucleation and causing radial ice growth. Rectifying the vials bottom with an adhesive material revealed to be a relatively simple alternative to overcome this inconsistency.

Spent fuel dissolution mechanisms

International Nuclear Information System (INIS)

Ollila, K.

1993-11-01

This study is a literature survey on the dissolution mechanisms of spent fuel under disposal conditions. First, the effects of radiolysis products on the oxidative dissolution mechanisms and rates of UO 2 are discussed. These effects have mainly been investigated by using electrochemical methods. Then the release mechanisms of soluble radionuclides and the dissolution of the UO 2 matrix including the actinides, are treated. Experimental methods have been developed for measuring the grain-boundary inventories of radionuclides. The behaviour of cesium, strontium and technetium in leaching tests shows different trends. Comparison of spent fuel leaching data strongly suggests that the release of 90 Sr into the leachant can be used as a measure of the oxidation/dissolution of the fuel matrix. Approaches to the modelling UO 2 , dissolution are briefly discussed in the next chapter. Lastly, the use of natural material, uraninite, in the evaluation of the long-term performance of spent fuel is discussed. (orig.). (81 ref., 37 figs., 8 tabs.)

Comparison of product drying performance in molded and serum tubing vials using gentamicin sulfate as a model system.

Science.gov (United States)

Hibler, Susanne; Wagner, Christophe; Gieseler, Henning

2012-01-01

In a previous study, heat transfer coefficients of different 10 mL tubing and molded vials were determined gravimetrically via sublimation tests with pure water. Contrary to "conventional wisdom", only small differences in K(v) values between tubing and molded vials were found in the pressure range relevant for pharmaceutical freeze-drying. In order to investigate the impact of these relatively small differences on the primary drying time of an actual product, freeze-drying experiments with 5% gentamicin sulfate solution as a model system were performed at 68, 100 and 200 mTorr. The primary drying times of the API in recently developed molded (EasyLyo™), tubing (TopLyo™) and polymer vials (TopPac™) were compared. At 68 and 100 mTorr the primary drying time of the drug in the glass vials only differed by 3% to 4%, while the polymer vial took around 9% longer. At 200 mTorr, the API in the EasyLyo™ vials dried approximately 15% faster compared to the other vial types. The present study suggest that molded vials that have been modified in design to have better heat transfer properties can achieve drying times comparable to tubing vials.

Residual volume in vials of antibiotics used in pediatrics.

Science.gov (United States)

Chaves, Caroline Magna Pessoa; Bezerra, Carolina Martins; Lima, Francisca Elisângela Teixeira; Cardoso, Maria Vera Lúcia Moreira Leitão; Fonseca, Said Gonçalves da Cruz; Silva, Viviane Martins da

2017-06-12

Quantifying residual volume contained in vials of antibiotics used in pediatrics. This is an experiment involving samples from vials of antibiotics used in a pediatric hospital. Residual volume was identified by calculating the difference in weight measurement before and after the vials were washed. Evaluation of the residual volume difference in the vials was determined by the Wilcoxon non-parametric test for a sample and established at a significance level of 5%. 105 samples of antibiotics were selected. The correct use of the antibiotics oxacillin (88.57%) and ceftriaxone (94.28%) predominated with low residual values. The same did not occur for procaine benzylpenicillin + potassium benzylpenicillin, since a greater residual volume was discarded in 74.28% of the vials. We highlight the need for improvements in managing antibiotics in the institution under study, so that the excess volume of the antibiotics in the vials is used within the acceptable stable time. It is also necessary that the disposal of the residual volume be adequately disposed, since it presents a risk to public health and the environment. Quantificar o volume residual contido em frascos-ampola de antibióticos utilizados na pediatria. Trata-se de um experimento com amostras de frascos-ampola de antibióticos utilizados em hospital pediátrico. O volume residual foi identificado calculando-se a diferença da aferição do peso antes e após a lavagem do frasco-ampola. A avaliação da diferença dos volumes residuais nos frascos-ampola foi determinada pelo teste não paramétrico de Wilcoxon para uma amostra e estabelecido o nível de significância de 5%. Foram selecionadas 105 amostras de antibióticos. Predominou o correto aproveitamento dos antibióticos oxacilina (88,57%) e ceftriaxona (94,28%), com baixos valores residuais. O mesmo não ocorreu com a benzilpenicilina procaína + potássica, pois em 74,28% dos frascos houve descarte de volume residual superior. Destaca-se a necessidade de

Biodegradation of [14C]phenol in secondary sewage and landfill leachate measured by double-vial radiorespirometry

International Nuclear Information System (INIS)

Deeley, G.M.; Skierkowski, P.; Robertson, J.M.

1985-01-01

Double-vial radiorespirometry was used to estimate the biodegradation rates of 14 C-labeled phenol in a landfill leachate and a secondary treated domestic wastewater. Rates were found to be comparable for each material at each of the three concentrations tested. Sewage microorganisms immediately began biodegrading the [ 14 C]phenol; landfill leachate microorganisms required a lag period before maximum biodegradation of the [ 14 C]phenol. The apparent rate of [ 14 C]phenol biodegradation was 2.4 times faster in the sewage than in the landfill leachate. Double-vial radiorespirometry was shown to be an effective method for screening biodegradation rates in aquifers

Modelo de gestión del tiempo en proyectos viales.

OpenAIRE

Luzuriaga Bojorque, Juan Pablo

2015-01-01

El presente trabajo demuestra la importancia de utilizar un método internacionalmente reconocido para gestionar la terminación de los proyectos viales a tiempo. Tanto entidad contratante como contratistas podrán utilizar las mejores prácticas en gerenciamiento de proyectos para lograr que la construcción de carreteras sean proyectos exitosos. Las entidades contratantes en el Ecuador, evalúan el cumplimiento del cronograma de un proyecto vial, en base de la consecución de un nivel determinado ...

Lack of clinical relevance in routine final subcultures of radiometrically negative BACTEC blood culture vials

International Nuclear Information System (INIS)

Plorde, J.J.; Carlson, L.G.; Dau, M.E.

1982-01-01

During a 38-month period, 10,106 blood specimens were received in the laboratory for culture. These were inoculated into 26,424 vials and processed using the BACTEC radiometric detection system. Of these vials, 1,914 were eventually found to be microbiologically positive. Isolates from 836 vials were judged to be contaminants. In the remaining 1,078 vials, growth was first detected visually or radiometrically in 1,062 and by final subculture in 16. Growth from these sixteen bottles represented 12 clinically significant bacteremic episodes in as many patients. In nine of these episodes, other culture vials from the same patient were positive radiometrically. Therefore, 358 of 361 (99.2%) bacteremic episodes were detected without the benefit of routine final subcultures. The three patients whose bacteremia was missed were diagnosed clinically and placed on appropriate therapy prior to the detection of the bacteremias by final subculture

Generating chimeric mice from embryonic stem cells via vial coculturing or hypertonic microinjection.

Science.gov (United States)

Lee, Kun-Hsiung

2014-01-01

The generation of a fertile embryonic stem cell (ESC)-derived or F0 (100 % coat color chimerism) mice is the final criterion in proving that the ESC is truly pluripotent. Many methods have been developed to produce chimeric mice. To date, the most popular methods for generating chimeric embryos is well sandwich aggregation between zona pellucida (ZP) removed (denuded) 2.5-day post-coitum (dpc) embryos and ESC clumps, or direct microinjection of ESCs into the cavity (blastocoel) of 3.5-dpc blastocysts. However, due to systemic limitations and the disadvantages of conventional microinjection, aggregation, and coculturing, two novel methods (vial coculturing and hypertonic microinjection) were developed in recent years at my laboratory.Coculturing 2.5-dpc denuded embryos with ESCs in 1.7-mL vials for ~3 h generates chimeras that have significantly high levels of chimerism (including 100 % coat color chimerism) and germline transmission. This method has significantly fewer instrumental and technological limitations than existing methods, and is an efficient, simple, inexpensive, and reproducible method for "mass production" of chimeric embryos. For laboratories without a microinjection system, this is the method of choice for generating chimeric embryos. Microinjecting ESCs into a subzonal space of 2.5-dpc embryos can generate germline-transmitted chimeras including 100 % coat color chimerism. However, this method is adopted rarely due to the very small and tight space between ZP and blastomeres. Using a laser pulse or Piezo-driven instrument/device to help introduce ESCs into the subzonal space of 2.5-dpc embryos demonstrates the superior efficiency in generating ESC-derived (F0) chimeras. Unfortunately, due to the need for an expensive instrument/device and extra fine skill, not many studies have used either method. Recently, ESCs injected into the large subzonal space of 2.5-dpc embryos in an injection medium containing 0.2-0.3 M sucrose very efficiently generated

Investigating the effect of moisture protection on solid-state stability and dissolution of fenofibrate and ketoconazole solid dispersions using PXRD, HSDSC and Raman microscopy.

Science.gov (United States)

Kanaujia, Parijat; Lau, Grace; Ng, Wai Kiong; Widjaja, Effendi; Schreyer, Martin; Hanefeld, Andrea; Fischbach, Matthias; Saal, Christoph; Maio, Mario; Tan, Reginald B H

2011-09-01

Enhanced dissolution of poorly soluble active pharmaceutical ingredients (APIs) in amorphous solid dispersions often diminishes during storage due to moisture-induced re-crystallization. This study aims to investigate the influence of moisture protection on solid-state stability and dissolution profiles of melt-extruded fenofibrate (FF) and ketoconazole (KC) solid dispersions. Samples were kept in open, closed and Activ-vials(®) to control the moisture uptake under accelerated conditions. During 13-week storage, changes in API crystallinity were quantified using powder X-ray diffraction (PXRD) (Rietveld analysis) and high sensitivity differential scanning calorimetry (HSDSC) and compared with any change in dissolution profiles. Trace crystallinity was observed by Raman microscopy, which otherwise was undetected by PXRD and HSDSC. Results showed that while moisture protection was ineffective in preventing the re-crystallization of amorphous FF, KC remained X-ray amorphous despite 5% moisture uptake. Regardless of the degree of crystallinity increase in FF, the enhanced dissolution properties were similarly diminished. Moisture uptake above 10% in KC samples also led to re-crystallization and significant decrease in dissolution rates. In conclusion, eliminating moisture sorption may not be sufficient in ensuring the stability of solid dispersions. Analytical quantification of API crystallinity is crucial in detecting subtle increase in crystallinity that can diminish the enhanced dissolution properties of solid dispersions.

Teaching Analytical Method Transfer through Developing and Validating Then Transferring Dissolution Testing Methods for Pharmaceuticals

Science.gov (United States)

Kimaru, Irene; Koether, Marina; Chichester, Kimberly; Eaton, Lafayette

2017-01-01

Analytical method transfer (AMT) and dissolution testing are important topics required in industry that should be taught in analytical chemistry courses. Undergraduate students in senior level analytical chemistry laboratory courses at Kennesaw State University (KSU) and St. John Fisher College (SJFC) participated in development, validation, and…

Stability of 10 mg/mL cefuroxime solution for intracameral injection in commonly used polypropylene syringes and new ready-to-use cyclic olefin copolymer sterile vials using the LC-UV stability-indicating method.

Science.gov (United States)

Feutry, Frédéric; Simon, Nicolas; Genay, Stéphanie; Lannoy, Damien; Barthélémy, Christine; Décaudin, Bertrand; Labalette, Pierre; Odou, Pascal

2016-01-01

Injecting intracameral cefuroxime has been found beneficial in reducing the risk of postoperative endophthalmitis but its use has been limited through a lack of approved marketing and of ready-to-use single-units as well as the problem of aseptic compounding. Our aim was to assess a new automated primary packaging system which should ensure a higher level of sterility, thanks to its closed, sterile, ready-to-use polymer vial called "Crystal® vial". The chemical stability of a 10 mg/mL cefuroxime solution was compared in 1 mL Crystal® vials and 1 mL Luer-lock polypropylene syringes (actual reference) to eliminate any potential and specific interactions with its cyclic olefin copolymer (COC) body and elastomer stopper. Cefuroxime solution was introduced into vials and syringes and stored at -20 °C, +5 °C and +25°C/60% Relative Humidity. Cefuroxime concentration and the relative amount of the main degradation product (descarbamoyl-cefuroxime) were both determined by an HPLC/UV method indicating stability. Solutions were considered steady if the concentration remained at over 90% of the initial value. In the adapted storage conditions, the evolution of osmolality, pH and sterility was assessed. Stability profiles were identical between vials and syringes in all storage and temperature conditions. The solution was stable (cefuroxime concentration, pH and osmolality) and still sterile for 365 days at -20°C. The concentration fell below 90% after 21 days at +5 °C and after 16 h at +25°C/60%s relative humidity. The COC and thermoplastic elastomer of the vials had no impact on the degradation process confirming its possible use for a ready-to-use cefuroxime solution single-unit dose.

In Vitro Dissolution Profile of Dapagliflozin: Development, Method Validation, and Analysis of Commercial Tablets

Directory of Open Access Journals (Sweden)

Rafaela Zielinski Cavalheiro de Meira

2017-01-01

Full Text Available Dapagliflozin was the first of its class (inhibitors of sodium-glucose cotransporter to be approved in Europe, USA, and Brazil. As the drug was recently approved, there is the need for research on analytical methods, including dissolution studies for the quality evaluation and assurance of tablets. The dissolution methodology was developed with apparatus II (paddle in 900 mL of medium (simulated gastric fluid, pH 1.2, temperature set at 37±0.5°C, and stirring speed of 50 rpm. For the quantification, a spectrophotometric (λ=224 nm method was developed and validated. In validation studies, the method proved to be specific and linear in the range from 0.5 to 15 μg·mL−1 (r2=0.998. The precision showed results with RSD values lower than 2%. The recovery of 80.72, 98.47, and 119.41% proved the accuracy of the method. Through a systematic approach by applying Factorial 23, the robustness of the method was confirmed (p>0.05. The studies of commercial tablets containing 5 or 10 mg demonstrated that they could be considered similar through f1, f2, and dissolution efficiency analyses. Also, the developed method can be used for the quality evaluation of dapagliflozin tablets and can be considered as a scientific basis for future official pharmacopoeial methods.

Dissolution testing of intermediary products in uranium dioxide production by the sol-gel method

International Nuclear Information System (INIS)

Melichar, F.; Landspersky, H.; Urbanek, V.

1979-01-01

A method was developed of dissolving polyuranates and uranium dioxides in sulphuric acid and in carbonate solutions for testing intermediate products in the sol-gel process preparation of uranium dioxide. A detailed granulometric analysis of spherical particle dispersion was included as part of the tests. Two different production methods were used for the two types of studied materials. The test results show that the test method is suitable for determining temperature sensitivity of the materials to dissolution reaction. The geometrical distribution of impurities in the spherical particles can be determined from the dissolution kinetics. The method allows the determination of the effect of carbon from impurities on the process of uranium dioxide leaching and is thus applicable for testing materials prepared by the sol-gel method. (Z.M.)

Development and Validation Dissolution Analytical Method of Nimesulide beta-Cyclodextrin 400 mg Tablet

Directory of Open Access Journals (Sweden)

Carlos Eduardo Carvalho Pereira

2016-10-01

Full Text Available The nimesulide (N-(4-nitro-2-phenoxyphenylmethanesulfonamide belongs to the class of non-steroidal anti-inflammatory drugs (NSAIDs and category II of the biopharmaceutical classification, The complexation of nimesulide with b-cyclodextrin is a pharmacological strategy to increase the solubility of the drug The objective of this study was to develop and validate an analytical methodology for dissolving the nimesulide beta-cyclodextrin 400 mg tablet and meets the guidelines of ANVISA for drug registration purposes. Once developed, the dissolution methodology was validated according to the RE of parameters no.  899/2003. In the development of the method it was noted that the duration of the dissolution test was 60 minutes, the volume and the most suitable dissolution medium was 900 mL of aqueous solution of sodium lauryl sulfate 1% (w/ v. It was also noted that rotation of 100 rpm and the paddle apparatus was the most appropriate to evaluate the dissolution of the drug. Spectrophotometric methodology was used to quantify the percentage of dissolved drug. The wavelength was 390 nm using the quantification. The validation of the methodology, system suitability parameters, specificity/selectivity, linearity, precision, accuracy and robustness were satisfactory and proved that the developed dissolution methodology was duly executed. DOI: http://dx.doi.org/10.17807/orbital.v8i5.827

Standard practice for measurement of the glass dissolution rate using the single-pass flow-through test method

CERN Document Server

American Society for Testing and Materials. Philadelphia

2010-01-01

1.1 This practice describes a single-pass flow-through (SPFT) test method that can be used to measure the dissolution rate of a homogeneous silicate glass, including nuclear waste glasses, in various test solutions at temperatures less than 100°C. Tests may be conducted under conditions in which the effects from dissolved species on the dissolution rate are minimized to measure the forward dissolution rate at specific values of temperature and pH, or to measure the dependence of the dissolution rate on the concentrations of various solute species. 1.2 Tests are conducted by pumping solutions in either a continuous or pulsed flow mode through a reaction cell that contains the test specimen. Tests must be conducted at several solution flow rates to evaluate the effect of the flow rate on the glass dissolution rate. 1.3 This practice excludes static test methods in which flow is simulated by manually removing solution from the reaction cell and replacing it with fresh solution. 1.4 Tests may be conducted wit...

Enhanced dissolution of meloxicam from orodispersible tablets prepared by different methods

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Ahmed Abd Elbary

2012-12-01

Full Text Available The objective of this study was formulation, development and evaluation of meloxicam orodispersible tablets. ODTs were prepared by two methods including sublimation technique where different subliming agents like camphor, menthol and thymol were used with Ac-Di-Sol as a superdisintegrant. Each subliming agent was used in three different concentrations (5, 10 and 15% w/w. Tablets were first prepared and later exposed to vacuum. Meloxicam ODTs were also prepared by freeze-drying an aqueous dispersion of meloxicam containing a matrix former, a sugar alcohol, and a collapse protectant. In addition, different disintegration accelerators were tested (each in 1% w/v including PVP K25, PVP K90, PEG 6000, PEG 4000, PEG 400, tween 80 and tween 20. The prepared ODTs from two methods were evaluated for weight variation, thickness, drug content, friability, hardness, wetting time, in vitro disintegration time and in vitro dissolution study. The best formulation was subjected to stability testing for 3 months at temperatures 40 °C and 75% relative humidity and at 60 °C. All formulations showed disintegration time ranging from 1 to 46 s. All the prepared formulae complied with the pharmacopoeial requirements of the drug contents. T17 gave the best in vitro disintegration and dissolution results. ODT formula T17 has shown no appreciable changes with respect to physical characters, meloxicam content and dissolution profiles when stored at elevated temperatures. In conclusion the results of this work suggest that orodispersible tablets of meloxicam with rapid disintegration time, fast drug release and good hardness can be efficiently and successfully formulated by employing freeze drying and sublimation methods.

Validation of a dissolution method with RP-HPLC analysis for Perindopril erbumine and Indapamide combination tablet

Directory of Open Access Journals (Sweden)

Jain P.S.

2012-01-01

Full Text Available A Dissolution method with high performance liquid chromatography (HPLC analysis was validated for perindopril erbumine and indapamide in combination tablet formulation. The method was validated to meet requirements for a global regulatory filing and this validation included specificity, linearity, accuracy, precision, range, robustness and solution stability studies. The dissolution method, which uses USP apparatus 1 with basket rotating at 100 rpm, 1000 ml of phosphate buffer pH 6.8 as the dissolution medium, and reversed-phased HPLC was carried out at 50⁰C on a 4.6mm×250mm 5μm cyano column that contained USP packing L1 with acetonitrile: buffer pH 2.8::40:60 (v/v, as mobile phase. UV detector was set at 225 nm. A method was found to be selective, linear, accurate and precise in the specified ranges. Intra-day and inter-day variability for method was <2% RSD. This method was successfully used for quantification of perindopril erbumine and indapamide combination tablet formulations.

Dissolution of uranium oxide TBP-HNO3 complex

International Nuclear Information System (INIS)

Mizuno, Mineo; Kosaka, Yuji; Mori, Yukihide; Shimada, Takashi

2002-12-01

As a head end process for the pulverization of the spent fuel, the mechanical method (the shredder method) and the pyro-chemical method (oxidisation heat-treatment) have been examined. UO 2 is a main ingredient of Uranium oxide powder by the mechanical method, and U 3 O 8 is that by the pyro-chemical method. Moreover, the particle size of the pulverized powder depend on the conditions of the pulverizing process. As it was considered that the difference of dissolution rates of samples was caused by the difference of sample chemical forms and dissolution temperature, parametric surveys on chemical form and particle size of powder and dissolution temperature were carried out, and the following results were obtained. 1) The remarkable difference of dissolution rate between U 3 O 8 powder (average particle size 3.7 μm) and UO 2 powder (average particle size 2.4 μm) which have comparatively similar particle size was not observed. 2) It was confirmed that the dissolution rate became lower according to the particle size increase (average particle size 2.4 μm-1 mm). And it was considered that dissolution rate had strong dependency on particle size, according to the results that the powder with 1 mm particle size did not dissolute completely after 5 hours test. 3) The temperature dependency of the dissolution rate was confirmed by dissolution test with UO 2 powder (average particle size 2.4 μm-1 mm). The higher dissolution rate was obtained in the higher dissolution temperature, and 11 kcal/mol was obtained as activation energy of dissolution. 4) In the dissolution test of UO 2 powder, the nitric acid concentration started to change earlier than that of U 3 O 8 powder and concentration change range became larger compared with that in the dissolution test of U 3 O 8 powder. It was considered that those differences were caused by difference in mole ratio of Uranium and nitric acid which are consumed in the dissolution reaction (3:7 for U 3 O 8 , 3:8 for UO 2 ). 5) In case

Development and validation of dissolution method for carvedilol compression-coated tablets

Directory of Open Access Journals (Sweden)

Ritesh Shah

2011-12-01

Full Text Available The present study describes the development and validation of a dissolution method for carvedilol compression-coated tablets. Dissolution test was performed using a TDT-06T dissolution apparatus. Based on the physiological conditions of the body, 0.1N hydrochloric acid was used as dissolution medium and release was monitored for 2 hours to verify the immediate release pattern of the drug in acidic pH, followed by pH 6.8 in citric-phosphate buffer for 22 hours, to simulate a sustained release pattern in the intestine. Influences of rotation speed and surfactant concentration in medium were evaluated. Samples were analysed by validated UV visible spectrophotometric method at 286 nm. 1% sodium lauryl sulphate (SLS was found to be optimum for improving carvedilol solubility in pH 6.8 citric-phosphate buffer. Analysis of variance showed no significant difference between the results obtained at 50 and 100 rpm. The discriminating dissolution method was successfully developed for carvedilol compression-coated tablets. The conditions that allowed dissolution determination were USP type I apparatus at 100 rpm, containing 1000 ml of 0.1N HCl for 2 hours, followed by pH 6.8 citric-phosphate buffer with 1% SLS for 22 hours at 37.0 ± 0.5 ºC. Samples were analysed by UV spectrophotometric method and validated as per ICH guidelines.O presente estudo descreve o desenvolvimento e a validação de método de dissolução para comprimidos revestidos de carvedilol. O teste de dissolução foi efetuado utilizando-se o aparelho para dissolução TDT-06T. Com base nas condições fisiológicas do organismo, utilizou-se ácido clorídrico 0,1 N como meio de dissolução e a liberação foi monitorada por 2 horas para se verificar o padrão de liberação imediata do fármaco em condições de pH baixo, seguidas por pH 6,8 em tampão cítrico-fosfato por 22 horas, para simular o padrão de liberação controlada no intestino. Avaliou-se a influência da velocidade de

Optimization of Dissolution Compartments in a Biorelevant Dissolution Apparatus Golem v2, Supported by Multivariate Analysis

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Ivan Stupák

2017-11-01

Full Text Available Biorelevant dissolution instruments represent an important tool for pharmaceutical research and development. These instruments are designed to simulate the dissolution of drug formulations in conditions most closely mimicking the gastrointestinal tract. In this work, we focused on the optimization of dissolution compartments/vessels for an updated version of the biorelevant dissolution apparatus—Golem v2. We designed eight compartments of uniform size but different inner geometry. The dissolution performance of the compartments was tested using immediate release caffeine tablets and evaluated by standard statistical methods and principal component analysis. Based on two phases of dissolution testing (using 250 and 100 mL of dissolution medium, we selected two compartment types yielding the highest measurement reproducibility. We also confirmed a statistically ssignificant effect of agitation rate and dissolution volume on the extent of drug dissolved and measurement reproducibility.

Comparison of PCE and TCE disappearance in heated volatile organic analysis vials and flame-sealed ampules.

Science.gov (United States)

Costanza, Jed; Pennell, Kurt D

2008-02-01

The rates of hydrolysis reported for tetrachloroethylene (PCE) and trichloroethylene (TCE) at elevated temperatures range over two orders-of-magnitude, where some of the variability may be due to the presence of a gas phase. Recent studies suggest that volatile organic analysis (VOA) vials provide a low-cost and readily available zero headspace system for measuring aqueous-phase hydrolysis rates. This work involved measuring rates of PCE and TCE disappearance and the corresponding appearance of dechlorination products in water-filled VOA vials and flame-sealed ampules incubated at 21 and 55 degrees C for up to 95.5 days. While PCE and TCE concentrations readily decreased in the VOA vials to yield first-order half lives of 11.2 days for PCE and 21.1 days for TCE at 55 degrees C, concentrations of anticipated dechlorination products, including chloride, remained constant or were not detected. The rate of PCE disappearance was 34 times faster in VOA vials at 55 degrees C compared to values obtained with flame-sealed ampules containing PCE-contaminated water. In addition, the concentration of TCE increased slightly in flame-sealed ampules incubated at 55 degrees C, while a decrease in TCE levels was observed in the VOA vials. The observed losses of PCE and TCE in the VOA vials were attributed to diffusion and sorption in the septa, rather than to dechlorination. These findings demonstrate that VOA vials are not suitable for measuring rates of volatile organic compound hydrolysis at elevated temperatures.

Development and validation of spectrophotometric method for assay determination and in vitro dissolution studies of sofosbuvir tablets

International Nuclear Information System (INIS)

Zaman, B.; Hassan, W.; Noreen, H.

2017-01-01

In vitro dissolution of sofosbuvir 400 mg tablets dosage form was performed, using USP dissolution apparatus type-II (paddle type), at 75rpm ± 4 %, and 900mL ± 1%, 0.05 M phosphate buffer pH 6.8 ± 0.05 equilibrated at 37.0 ± 0.5ºC as dissolution medium. Percentage of dissolved sofosbuvir as a function of time was determined using the straight line equation and linear regression using zero order and first order ANOVA based kinetics model. Comparative dissolution studies on two different generic brands A and B was performed comparing the drug release profile with innovator brand Sovaldi 400 mg tablets. The comparison of dissolution profiles was evaluated using model independent approach. The values of similarity factor f2 were (4 and 3) and the difference factor f1 were (64 and 50) for both generic products A and B respectively. A simple and precise spectrophotometric method was developed for estimation of sofosbuvir in dissolution medium based on spectrophotometric detection at wavelength 262 nm. The specific absorbance (A = 1%) of sofosbuvir was 178.5 ± 4% and Beer’s law was obeyed in the concentration ranges 4µg mL−1 to 48µg mL−1. The method was validated appropriately for accuracy, precision, linearity, and specificity, according the guidelines of United State Pharmacopoeia and International Conference on Harmonization. The calibration curve was linear with correlation coefficient (r > 0.9999) and there was no spectral interference from excipients present in the tablets dosage form. This method is precise, rapid and specific for determination of sofosbuvir in tablets dosage form and successfully applied for assay determination and in vitro dissolution studies. (author)

Validated, Ultra Violet Spectroscopy method for the Dissolution study of Mycophenolate mofetil immediate release 500mg tablets

OpenAIRE

Surajpal P. Verma; Ozair Alam; Pooja Mullick; Nadeem Siddiqui; Suroor A. Khan

2008-01-01

A simple, selective and precise dissolution method was developed and validated for the Mycophenolate mofetil immediate release tablets. The method employed dissolution medium 0.1N HCl (pH1.2) and volume 900ml with USP-II apparatus (Paddle). Detection was made by measuring the absorbance on UV at the [lambda]~max~ 250nm. The method show the linearity in the range of conc. 5[micro]g/ml to 40[micro]g/ml with r^2^=0.999. The method is also validated as per International Conference of Harmonizatio...

The measurement of activity in vials and syringes using a radionuclide assay calibrator

International Nuclear Information System (INIS)

Hooper, S.A.; Davies, I.H.

1993-01-01

To enable accurate measurements of the activity in both vials and syringes, a series of measurements was undertaken to ascertain the changes in response with geometry in nine isotope assay calibrators. From these measurements, two jigs were made for each calibrator to enable (a) optimal measurement of activity in vials and (b) optimal measurement of activity in a variety of syringe sizes. (Author)

Experiencia-modelo piloto de los talleres de seguridad vial, como alternativa a la pena privativa de libertad en los delitos contra la seguridad vial

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Isabel Germán Mancebo

2012-12-01

Full Text Available Algunos de los delitos contra la seguridad vial en España tienen asignada la pena de trabajos en beneficio de la comunidad (TBC. Y en la práctica se han percibido problemas en su implementación, entre otros motivos por el aumento de la comisión de los delitos de tránsito y la escasez de puestos de trabajo social para poder llevar a cabo los trabajos comunitarios. Tanto la reciente modificación del Código Penal, como de la normativa reguladora de esta sanción, permite desarrollar los TBC por medio de la realización de talleres. En este artículo se presenta la experiencia-modelo piloto de los talleres de seguridad vial que dan contenido a la pena de TBC, como alternativa a la pena privativa de libertad, lo que resulta de especial interés al ser una de las primeras experiencias de esta naturaleza en España. Para ello se describen los talleres desarrollados, mensualmente, durante el año 2010, a saber: su primer año de funcionamiento en la provincia de Gipuzkoa (España, detallando su estructura, dinámica y tareas -tanto formativas como de utilidad pública- que realizaron los penados. La implementación de estos talleres ha paliado las deficiencias percibidas en la aplicación de la pena de TBC, dotándola de contenido, y superando así las críticas a las que esta sanción se había visto expuesta. Los talleres de seguridad vial responden de forma efectiva al papel preventivo que se le ha otorgado a este tipo de sanciones en el ámbito de la seguridad vial.

Polyethylene vials for liquid scintillation counters produced by the National Materials Research Institute

International Nuclear Information System (INIS)

Fiser, B.; Lukas, D.

1984-01-01

The properties were tested of polyethylene vials for liquid scintillation counters manufactured by the National Materials Research Institute. Liquid scintillation counter ISOCAP 300 by Nuclear Chicago was used for measuring. For unquenched samples, channel A was set up to 0.5-3.6 keV and channel B to 0.5-18 keV. The scintillation solution was prepared of toluene, 4 g PPO, 0.15 g POPOP per 1 l of toluene. CCl 4 was used as the quenching agent. Radioactive samples were prepared from 20 μl of standard solution of [ 3 H]-toluene with specific activity of 349 Bq/g. All measurements were made using a 7 ml scintillation solution into which radioactivity and possibly quenching agents were added. Potassium-free glass vials by SKLO UNION Teplice and thin-walled polyethylene vials by Nuclear Chicago were used for comparison. The background was measured, as were the time dependences of weight losses of the scintillation solution and carbon tetrachloride from the counting vials, changes in efficiency in channel B with time, changes in SCR with time and changes in the quenching curve with time. (E.S.)

Isolation of HIV-1 from experimentally contaminated multidose local anaesthetic vials.

Science.gov (United States)

Druce, J D; Locarnini, S A; Birch, C J

1995-05-15

To investigate the hypothesis that HIV can be transmitted via contamination of multidose vials of local anaesthetic solution through reuse of needles and syringes. Laboratory study. (1) By experiments with multidose vials and disposable needles and syringes, we identified a sequence of events in which HIV could contaminate the anaesthetic solution. (2) Three anaesthetic solutions were contaminated with a laboratory strain of HIV and tested by viral culture and p24 enzyme immunoassay one, two and four hours later to see how long the virus remained active. (1) Needles and syringes retained small volumes of fluid after use (mean, 25 microL; in syringe alone, mean 16 microL) which could be transferred to multidose vials of local anaesthetic. (2) 10 mL of anaesthetic solution contaminated with 8 microL of HIV-infected solution (equivalent to 1% infected lymphocytes in vivo) contained active virus one hour later. In some settings, HIV could be isolated four hours after exposure. When inadvertently contaminated with HIV, multidose solutions represent a potential source of transmissible virus.

Characteristics of high-purity Teflon vial for 14C measurement in old tree rings

International Nuclear Information System (INIS)

Sakurai, H.; Saswaki, Y.; Matsumoto, T.; Aoki, T.; Kato, W.; Gandou, T.; Gunji, S.; Tokanai, F.

2003-01-01

14 C concentration in single-year tree rings of an old cedar of ca. 2500 years ago is measured to investigate the 11-yr periodicity of solar activity. Our highly accurate 14 C measuring system is composed of a benzene synthesizer capable of producing a large quantity (10 g) of benzene and a Quantulus 1220 TM liquid scintillation counting system. The accuracy is less than 0.2% for measurements of 14 C concentration. The benzene sample is contained in a high-purity Teflon/copper-counting vial (20 ml) manufactured by Wallac Oy Company. We found a vial with an irregular copper cap for the measurements of 11 tree rings. The behavior of the vial with the irregular cap was investigated. The Teflon sheet inside the cap plays an important role in achieving stable measurement. The rate of volatilization of the benzene was less than 0.35 mg/day for vials with ordinary caps. This results in the volatilization rate of 0.003% for 10.5 g of benzene and hence guarantees measurement at an accuracy of 0.2% for 70 days

Indomethacin nanocrystals prepared by different laboratory scale methods: effect on crystalline form and dissolution behavior

Energy Technology Data Exchange (ETDEWEB)

Martena, Valentina; Censi, Roberta [University of Camerino, School of Pharmacy (Italy); Hoti, Ela; Malaj, Ledjan [University of Tirana, Department of Pharmacy (Albania); Di Martino, Piera, E-mail: piera.dimartino@unicam.it [University of Camerino, School of Pharmacy (Italy)

2012-12-15

The objective of this study is to select very simple and well-known laboratory scale methods able to reduce particle size of indomethacin until the nanometric scale. The effect on the crystalline form and the dissolution behavior of the different samples was deliberately evaluated in absence of any surfactants as stabilizers. Nanocrystals of indomethacin (native crystals are in the {gamma} form) (IDM) were obtained by three laboratory scale methods: A (Batch A: crystallization by solvent evaporation in a nano-spray dryer), B (Batch B-15 and B-30: wet milling and lyophilization), and C (Batch C-20-N and C-40-N: Cryo-milling in the presence of liquid nitrogen). Nanocrystals obtained by the method A (Batch A) crystallized into a mixture of {alpha} and {gamma} polymorphic forms. IDM obtained by the two other methods remained in the {gamma} form and a different attitude to the crystallinity decrease were observed, with a more considerable decrease in crystalline degree for IDM milled for 40 min in the presence of liquid nitrogen. The intrinsic dissolution rate (IDR) revealed a higher dissolution rate for Batches A and C-40-N, due to the higher IDR of {alpha} form than {gamma} form for the Batch A, and the lower crystallinity degree for both the Batches A and C-40-N. These factors, as well as the decrease in particle size, influenced the IDM dissolution rate from the particle samples. Modifications in the solid physical state that may occur using different particle size reduction treatments have to be taken into consideration during the scale up and industrial development of new solid dosage forms.

14C sample preparation for AMS microdosing studies at Lund University using online combustion and septa-sealed vials

Science.gov (United States)

Sydoff, Marie; Stenström, Kristina

2010-04-01

The Department of Physics at Lund University is participating in a European Union project called EUMAPP (European Union Microdose AMS Partnership Programme), in which sample preparation and accelerator mass spectrometry (AMS) measurements of biological samples from microdosing studies have been made. This paper describes a simplified method of converting biological samples to solid graphite for 14C analysis with AMS. The method is based on online combustion of the samples, and reduction of CO 2 in septa-sealed vials. The septa-sealed vials and disposable materials are used to eliminate sample cross-contamination. Measurements of ANU and Ox I standards show deviations of 2% and 3%, respectively, relative to reference values. This level of accuracy is sufficient for biological samples from microdosing studies. Since the method has very few handling steps from sample to graphite, the risk of failure during the sample preparation process is minimized, making the method easy to use in routine preparation of samples.

14C sample preparation for AMS microdosing studies at Lund University using online combustion and septa-sealed vials

International Nuclear Information System (INIS)

Sydoff, Marie; Stenstroem, Kristina

2010-01-01

The Department of Physics at Lund University is participating in a European Union project called EUMAPP (European Union Microdose AMS Partnership Programme), in which sample preparation and accelerator mass spectrometry (AMS) measurements of biological samples from microdosing studies have been made. This paper describes a simplified method of converting biological samples to solid graphite for 14 C analysis with AMS. The method is based on online combustion of the samples, and reduction of CO 2 in septa-sealed vials. The septa-sealed vials and disposable materials are used to eliminate sample cross-contamination. Measurements of ANU and Ox I standards show deviations of 2% and 3%, respectively, relative to reference values. This level of accuracy is sufficient for biological samples from microdosing studies. Since the method has very few handling steps from sample to graphite, the risk of failure during the sample preparation process is minimized, making the method easy to use in routine preparation of samples.

Dissolution profiles of perindopril and indapamide in their fixed-dose formulations by a new HPLC method and different mathematical approaches

Directory of Open Access Journals (Sweden)

Gumieniczek Anna

2015-09-01

Full Text Available A new HPLC method was introduced and validated for simultaneous determination of perindopril and indapamide. Validation procedure included specificity, sensitivity, robustness, stability, linearity, precision and accuracy. The method was used for the dissolution test of perindopril and indapamide in three fixed-dose formulations. The dissolution procedure was optimized using different media, different pH of the buffer, surfactants, paddle speed and temperature. Similarity of dissolution profiles was estimated using different model-independent and model-dependent methods and, additionally, by principal component analysis (PCA. Also, some kinetic models were checked for dissolved amounts of drugs as a function of time.

Dissolution of nuclear fuels

International Nuclear Information System (INIS)

Uriarte Hueda, A.; Berberana Eizmendi, M.; Rainey, R.

1968-01-01

A laboratory study was made of the instantaneous dissolution rate (IDR) for unirradiated uranium metal rods and UO 2 , PuO 2 and PuO 2 -UO 2 pellets in boiling nitric acid alone and with additives. The uranium metal and UO 2 dissolved readily in nitric acid alone; PuO 2 dissolved slowly even with the addition of fluoride; PuO 2 -UO 2 pellets containing as much as 35% PuO 2 in UO 2 gave values of the instantaneous dissolution rate to indicate can be dissolved with nitric acid alone. An equation to calculate the time for complete dissolution has been determinate in function of the instantaneous dissolution rates. The calculated values agree with the experimental. Uranium dioxide pellets from various sources but all having a same density varied in instantaneous dissolution rate. All the pellets, however, have dissolved ved in the same time. The time for complete dissolution of PuO 2 -UO 2 pellets, having the same composition, and the concentration of the used reagents are function of the used reagents are function of the fabrication method. (Author) 8 refs

Comparison of vials and prefilled pens of a rapid-acting insulin analog on pharmacy budgets in a long-term care setting.

Science.gov (United States)

Eby, Elizabeth L; Smolen, Lee J; Pitts, Amber C; Krueger, Linda A; Andrews, Jeffrey Scott

2014-12-01

Estimate budgetary impact for skilled nursing facility converting from individual patient supply (IPS) delivery of rapid-acting insulin analog (RAIA) 10-mL vials or 3-mL prefilled pens to 3-mL vials. A budget-impact model used insulin volume purchased and assumptions of length of stay (LOS), daily RAIA dose, and delivery protocol to estimate the cost impact of using 3-mL vials. Skilled nursing facility. Medicare Part A patients. Simulations conducted using 12-month current and future scenarios. Comparisons of RAIA use for 13- and 28-day LOS. RAIA costs and savings, waste reduction. For patients with 13-day LOS using 20 units/day of IPS insulin, the model estimated a 70% reduction in RAIA costs and units purchased and a 95% waste reduction for the 3-mL vial compared with the 10-mL vial. The estimated costs for prefilled pen use were 58% lower than for use of 10-mL vials. The incremental savings associated with 3-mL vial use instead of prefilled pens was 28%, attributable to differences in per-unit cost of insulin in vials versus prefilled pens. Using a more conservative scenario of 28-day LOS at 20 units/day, the model estimated a 40% reduction in RAIA costs and units purchased, resulting in a 91% reduction in RAIA waste for the 3-mL vial, compared with 10-mL vial. Budget-impact analysis of conversion from RAIA 10-mL vials or 3-mL prefilled pens to 3-mL vials estimated reductions in both insulin costs and waste across multiple scenarios of varying LOS and patient daily doses for skilled nursing facility stays.

Seguridad Vial y Procesos Psicológicos: Acciones Preventivas. [ Road Safety and Psychological Processes: Preventive Actions

OpenAIRE

Manuel Ernesto Riaño Garzón; Nathalie Claire Raynaud Prado; Edgar Alexis Diaz Camargo

2017-01-01

El artículo revisa la relación entre los procesos psicológicos y la seguridad vial desde una postura preventiva con el fin de proporcionar evidencias sobre alternativas utilizadas en terapia que puedan ser de utilidad para el adecuado funcionamiento psico-fisiológico y que determinen una mayor Seguridad Vial. Dicha revisión resulta pertinente en el marco de la Policía Nacional y de la Seguridad Vial en tanto ilustra metodologías empíricamente validadas que pueden ser utilizadas por las person...

78 FR 14095 - Determination That GEREF (Sermorelin Acetate) Injection, 0.5 Milligrams Base/Vial and 1.0...

Science.gov (United States)

2013-03-04

...] Determination That GEREF (Sermorelin Acetate) Injection, 0.5 Milligrams Base/Vial and 1.0 Milligrams Base/Vial, and GEREF (Sermorelin Acetate) Injection, 0.05 Milligrams Base/Amp, Were Not Withdrawn From Sale for...

Effect of sodium lauryl sulfate in dissolution media on dissolution of hard gelatin capsule shells.

Science.gov (United States)

Zhao, Fang; Malayev, Vyacheslav; Rao, Venkatramana; Hussain, Munir

2004-01-01

Sodium lauryl sulfate (SLS) is a commonly used surfactant in dissolution media for poorly water soluble drugs. However, it has occasionally been observed that SLS negatively impacts the dissolution of drug products formulated in gelatin capsules. This study investigated the effect of SLS on the dissolution of hard gelatin capsule shells. The USP paddle method was used with online UV monitoring at 214 nm (peptide bond). Empty size #0 capsule shells were held to the bottom of the dissolution vessel by magnetic three-prong sinkers. SLS significantly slowed down the dissolution of gelatin shells at pH < 5. Visually, the gelatin shells transformed into some less-soluble precipitate under these conditions. This precipitate was found to contain a higher sulfur content than the gelatin control sample by elemental analysis, indicating that SLS is part of the precipitate. Additionally, the slowdown of capsule shell dissolution was shown to be dependent on the SLS concentration and the ionic strength of the media. SLS interacts with gelatin to form a less-soluble precipitate at pH < 5. The use of SLS in dissolution media at acidic pH should be carefully evaluated for gelatin capsule products.

{sup 14}C sample preparation for AMS microdosing studies at Lund University using online combustion and septa-sealed vials

Energy Technology Data Exchange (ETDEWEB)

Sydoff, Marie, E-mail: marie.sydoff@med.lu.s [Department of Clinical Sciences, Medical Radiation Physics, Malmo University Hospital, SE-205 02 Malmoe (Sweden); Lund University, Department of Physics, Division of Nuclear Physics, P.O. Box 118, SE-221 00 Lund (Sweden); Stenstroem, Kristina [Lund University, Department of Physics, Division of Nuclear Physics, P.O. Box 118, SE-221 00 Lund (Sweden)

2010-04-15

The Department of Physics at Lund University is participating in a European Union project called EUMAPP (European Union Microdose AMS Partnership Programme), in which sample preparation and accelerator mass spectrometry (AMS) measurements of biological samples from microdosing studies have been made. This paper describes a simplified method of converting biological samples to solid graphite for {sup 14}C analysis with AMS. The method is based on online combustion of the samples, and reduction of CO{sub 2} in septa-sealed vials. The septa-sealed vials and disposable materials are used to eliminate sample cross-contamination. Measurements of ANU and Ox I standards show deviations of 2% and 3%, respectively, relative to reference values. This level of accuracy is sufficient for biological samples from microdosing studies. Since the method has very few handling steps from sample to graphite, the risk of failure during the sample preparation process is minimized, making the method easy to use in routine preparation of samples.

Crystal modifications and dissolution rate of piroxicam.

Science.gov (United States)

Lyn, Lim Yee; Sze, Huan Wen; Rajendran, Adhiyaman; Adinarayana, Gorajana; Dua, Kamal; Garg, Sanjay

2011-12-01

Piroxicam is a nonsteroidal anti-inflammatory drug with low aqueous solubility which exhibits polymorphism. The present study was carried out to develop polymorphs of piroxicam with enhanced solubility and dissolution rate by the crystal modification technique using different solvent mixtures prepared with PEG 4000 and PVP K30. Physicochemical characteristics of the modified crystal forms of piroxicam were investigated by X-ray powder diffractometry, FT-IR spectrophotometry and differential scanning calorimetry. Dissolution and solubility profiles of each modified crystal form were studied and compared with pure piroxicam. Solvent evaporation method (method I) produced both needle and cubic shaped crystals. Slow crystallization from ethanol with addition of PEG 4000 or PVP K30 at room temperature (method II) produced cubic crystal forms. Needle forms produced by method I improved dissolution but not solubility. Cubic crystals produced by method I had a dissolution profile similar to that of untreated piroxicam but showed better solubility than untreated piroxicam. Cubic shaped crystals produced by method II showed improved dissolution, without a significant change in solubility. Based on the XRPD results, modified piroxicam crystals obtained by method I from acetone/benzene were cube shaped, which correlates well with the FTIR spectrum; modified needle forms obtained from ethanol/methanol and ethanol/acetone showed a slight shift of FTIR peak that may be attributed to differences in the internal structure or conformation.

Stability of Procainamide Injection in Clear Glass Vials and Polyvinyl Chloride Bags.

Science.gov (United States)

Donnelly, Ronald F

2017-11-01

The objective of this study was to evaluate the chemical stability of procainamide hydrochloride, 100 mg/mL, when repackaged in clear glass vials or diluted to 3 mg/mL with normal saline and packaged in polyvinyl chloride (PVC) bags when stored at either 23°C and exposed to light (ETL) or 5°C and protected from light (PFL). Solutions were assayed using a stability-indicating high-performance liquid chromatography method. Samples (5 mL) were collected from triplicate containers on days 0, 7, 14, 21, 28, 56, 91, and 193. Color/clarity and pH changes were also monitored at each time interval. During the study, all samples remained clear and there was only a slight pH change. The color of the solutions stored at 23°C intensified but did not correlate with a significant decrease in concentration, while solutions stored at 5°C remained unchanged. Solutions repackaged in glass vials were stable for 193 days when stored at 23ºC and ETL or 5ºC and PFL. When further diluted to 3 mg/mL with normal saline and packaged in PVC bags, procainamide was also stable for 193 days at either 23ºC and ETL or 5°C and PFL. The stability of procainamide, 100 mg/mL, repackaged in clear glass vials was 193 days when stored at either 23ºC and ETL or 5ºC or PFL. If diluted further to 3 mg/mL with normal saline and packaged in PVC bags, the drug was also stable for 193 days at either 23ºC and ETL or 5°C and PFL.

The in Vitro Release of Indomethacin from Suppositories: Effects of Bases and Comparison of Different Dissolution Methods.

Science.gov (United States)

Mori, Kenji; Hori, Seiichi; Kawata, Tsubasa; Kogure, Sanae; Matsumoto, Kaori; Hasegawa, Tetsuya; Akimoto, Masayuki

2017-01-01

The suitability of apparatuses for the quality control of indomethacin (IND, 50 mg) compounded suppositories was evaluated and the effects of the type of suppository base on release profiles was investigated. The release characteristics of hydrophilic and lipophilic suppositories containing IND were compared using four types of dissolution methods: basket (RB), paddle (PD), dialysis tubing (DT) and flow-through cell (FTC). The release process was evaluated using the following model independent parameters: the mean dissolution time (MDT), cumulative percent of drug released (Q) at the end of the sampling time, and dissolution efficiency (DE). The fastest and most reproducible release profiles were observed for a hydrophilic base (macrogols), which resulted in more than 90% of the drug being released in 30 min using PD, RB and FTC. After 90 min, 90% of the total amount of the drug was released from a mixture of hydrophilic bases with a lipophilic base (macrogols and hard fat) in compendial dissolution methods and the mixture base was the second fastest only to the hydrophilic base. The slowest release profiles in each method were observed for the lipophilic base (hard fat). Poor drug release from any type of suppository base was noted using DT. Based on the results of the present study, FTC may be regarded as an adequate technique allowing sufficient discriminating power for the quality control of IND compounded suppositories.

Determination of {sup 226}Ra by gamma spectrometry: study of packaging vial of sample for analysis; Determinacao de {sup 226}Ra por espectrometria gama: estudo do recipiente de acondicionamento de amostra para analise

Energy Technology Data Exchange (ETDEWEB)

Carneiro, Andre Cavalcanti

2015-07-01

Determination of radioactivity levels of {sup 226}Ra by gamma spectrometry in a sample is based on measurements of {sup 214}Pb and {sup 214}Bi, daughters of {sup 222}Rn. Because radon is a gas, it can leak from the sample vial or accumulate on the upper empty it. If the vial has any crack, there will be loss of gas, which will cause error in determining the {sup 226}Ra concentration. One possible cause of cracks in the vials, that houses standards and samples, is the radiolysis action in the vial material, usually a polymer. As the demand {sup 226}Ra analysis in different matrices (geological samples, food, plants, etc.) is increasing, it was decided to study some polymer vials available on the market, to verify the feasibility to be used when is applied the analysis method using gamma spectrometry. Four types of polymer vials have been studied. The radiation doses in walls of the vials caused by natural radionuclides present in the sample were simulated using gamma irradiation. Tests, such as compressive strength test and tightness, were applied to the irradiated and non-irradiated vials. First, to verify the effect of radiolysis on the vial material and also if there was {sup 222}Rn diffusion in their walls. These preliminary results pointed out that the acrylic vials are the best option of packaging samples for analysis. This study should be repeated in a larger number of samples for a better evaluation. (author)

Proteja a sus seres queridos de las lesiones viales

Centers for Disease Control (CDC) Podcasts

Este podcast, que forma parte de la iniciativa Proteja a sus seres queridos, aborda las medidas que pueden tomar los padres de familia para ayudar a proteger a sus niños de las lesiones viales, una de las principales causas de lesiones infantiles.

Determination of the influence factors of the radiopharmaceutical vials dimensions used for activimeter calibration at IPEN

International Nuclear Information System (INIS)

Martins, E.W.; Potiens, M.P.A.

2012-01-01

This paper presents the establishment of a quality control program and correction factors for the geometry of the vials used for distribution of radiopharmaceutical and activimeters calibration. The radiopharmaceutical produced by IPEN 67 Ga, 131 I, 201 Tl and 99m Tc had been tested using two different vials. Results show a maximum variation of 22% for 201 Tl, and the minimum variation was 2.98% for 131 I. The correction factors must be incorporated in the routine calibration of the activimeters. - Highlights: ► Establishement of quality control program for reference activimeters. ► Determination of correction factors for the geometry of vials. ► Radiopharmaceuticals tested for different vials were 67 Ga, 131 I, 201 Tl and 99m Tc. ► The maximum variation was 22% for 201 Tl and the minimum variation was 2.98% for 131 I. ► Correction factors must be incorporated in the calibration of the activimeters.

Impact of changing the measles vaccine vial size on Niger's vaccine supply chain: a computational model.

Science.gov (United States)

Assi, Tina-Marie; Brown, Shawn T; Djibo, Ali; Norman, Bryan A; Rajgopal, Jayant; Welling, Joel S; Chen, Sheng-I; Bailey, Rachel R; Kone, Souleymane; Kenea, Hailu; Connor, Diana L; Wateska, Angela R; Jana, Anirban; Wisniewski, Stephen R; Van Panhuis, Willem G; Burke, Donald S; Lee, Bruce Y

2011-06-02

Many countries, such as Niger, are considering changing their vaccine vial size presentation and may want to evaluate the subsequent impact on their supply chains, the series of steps required to get vaccines from their manufacturers to patients. The measles vaccine is particularly important in Niger, a country prone to measles outbreaks. We developed a detailed discrete event simulation model of the vaccine supply chain representing every vaccine, storage location, refrigerator, freezer, and transport device (e.g., cold trucks, 4 × 4 trucks, and vaccine carriers) in the Niger Expanded Programme on Immunization (EPI). Experiments simulated the impact of replacing the 10-dose measles vial size with 5-dose, 2-dose and 1-dose vial sizes. Switching from the 10-dose to the 5-dose, 2-dose and 1-dose vial sizes decreased the average availability of EPI vaccines for arriving patients from 83% to 82%, 81% and 78%, respectively for a 100% target population size. The switches also changed transport vehicle's utilization from a mean of 58% (range: 4-164%) to means of 59% (range: 4-164%), 62% (range: 4-175%), and 67% (range: 5-192%), respectively, between the regional and district stores, and from a mean of 160% (range: 83-300%) to means of 161% (range: 82-322%), 175% (range: 78-344%), and 198% (range: 88-402%), respectively, between the district to integrated health centres (IHC). The switch also changed district level storage utilization from a mean of 65% to means of 64%, 66% and 68% (range for all scenarios: 3-100%). Finally, accounting for vaccine administration, wastage, and disposal, replacing the 10-dose vial with the 5 or 1-dose vials would increase the cost per immunized patient from $0.47US to $0.71US and $1.26US, respectively. The switch from the 10-dose measles vaccines to smaller vial sizes could overwhelm the capacities of many storage facilities and transport vehicles as well as increase the cost per vaccinated child.

Reexamining the Dissolution of Spent Fuel: A Comparison of Different Methods for Calculating Rates

International Nuclear Information System (INIS)

Hanson, Brady D.; Stout, Ray B.

2004-01-01

Dissolution rates for spent fuel have typically been reported in terms of a rate normalized to the surface area of the specimen. Recent evidence has shown that neither the geometric surface area nor that measured with BET accurately predicts the effective surface area of spent fuel. Dissolution rates calculated from results obtained by flowthrough tests were reexamined comparing the cumulative releases and surface area normalized rates. While initial surface area is important for comparison of different rates, it appears that normalizing to the surface area introduces unnecessary uncertainty compared to using cumulative or fractional release rates. Discrepancies in past data analyses are mitigated using this alternative method

Dissolution of metallic uranium and its alloys. Part 1. Review of analytical and process-scale metallic uranium dissolution

International Nuclear Information System (INIS)

Laue, C.A.; Gates-Anderson, D.; Fitch, T.E.

2004-01-01

This review focuses on dissolution/reaction systems capable of treating uranium metal waste to remove its pyrophoric properties. The primary emphasis is the review of literature describing analytical and production-scale dissolution methods applied to either uranium metal or uranium alloys. A brief summary of uranium's corrosion behavior is included since the corrosion resistance of metals and alloys affects their dissolution behavior. Based on this review, dissolution systems were recommended for subsequent screening studies designed to identify the best system to treat depleted uranium metal wastes at Lawrence Livermore National Laboratory (LLNL). (author)

Dissolution test of herbal medicines containing Paullinia cupana: validation of methods for quantification and assessment of dissolution

Directory of Open Access Journals (Sweden)

Sandra Alves de Sousa

2011-06-01

Full Text Available "Guaraná" (Paullinia cupana is used as a physical activity enhancer and stimulator due to its methylxanthines and condensed tannins. The aim of this work was to evaluate the dissolution behavior of five herbal medicines in the form of capsules and tablets containing guaraná. Assay and dissolution methods were validated and results obtained allowed simultaneous marker quantification with precision, accuracy, selectivity and robustness. Findings showed that 100% of the herbal medicinal products analyzed did not provide satisfactory results concerning the presence of four markers, 60% had three markers (caffeine, catechin and epicatechin, while 40% had only caffeine at tested dosage forms. In addition, after 30 minutes, only capsule A showed at least 80% of the dissolved markers. In other capsules, marker dissolution did not exceed 60% whereas 60% of the samples had some characteristic pharmacotechnical problems. These results evidence the need for rigorous quality control to help ensure the therapeutic action of these drugs. To this end, dissolution studies are an essential tool for quality assurance of herbal medicines.Guaraná (Paullinia cupana é utilizado como revigorante e estimulante devido à presença de metilxantinas e taninos condensados. Este trabalho visou avaliar o comportamento de dissolução de cinco fitoterápicos, na forma de cápsulas e comprimidos, contendo guaraná. O método de quantificação e de dissolução foram validados e os resultados obtidos permitiram a quantificação dos marcadores simultaneamente, com precisão, exatidão, seletividade e robustez. Foi verificado que 100% dos fitoterápicos analisados encontravam em desacordo quanto à presença dos quatro marcadores, sendo que 60% apresentaram três marcadores (cafeína, catequina e epicatequina e 40% apresentaram somente a cafeína. Além disso, após o tempo de 30 minutos de ensaio foi possível observar que somente a cápsula A apresentou pelo menos 80% dos

Laser Scanner Como Sistema de Detección de Entornos Viales

Directory of Open Access Journals (Sweden)

F. García

2011-01-01

Full Text Available Resumen: Los últimos avances en seguridad vial, con sistemas cada vez más complejos, requieren de los más modernos sistemas de adquisición de información. La naturaleza misma del problema requiere sensores capaces de proveer información fiable para tareas complejas y exigentes. Los escáneres láser (LIDAR han demostrado ser una familia de sensores altamente fiable, por lo que durante los últimos años los esfuerzos dedicados a investigar posibles aplicaciones viales han ido en aumento. De esta forma, es cada vez más frecuente observar sistemas de ayuda a la conducción (ADAS con este tipo de dispositivos que proveen de información del entorno necesaria para realizar tareas complejas como deteccián y prediccián de situaciones peligrosas. En el presente trabajo, dos sistemas LIDAR han sido probados para comprobar sus capacidades reales en entornos viales. En segundo término, se propone una aplicación que hace uso de las capacidades de dichos sensores para la detección y clasificación de obstaculos en entornos viarios. Palabras clave: sensores, procesamiento de senales, sistemas reales, vehiculos, algoritmos de deteccion

Development and validation of dissolution test for Metoprolol ...

African Journals Online (AJOL)

The dissolution method which uses USP apparatus I (Basket) with rotating at 100 rpm, 900 ml of different dissolution medium, ultra violet spectroscopy for quantification was demonstrated to be robust, discriminating and transferable. Dissolution tests conditions were selected after it was demonstrated that the Metoprolol ...

Improvements in and environmental applications of double-vial radiorespirometry for the study of microbial mineralization

International Nuclear Information System (INIS)

McKinley, V.L.; Federle, T.W.; Vestal, J.R.

1983-01-01

Several variations in the scintillation mixture and the filter paper arrangements for double-vial radiorespirometry were compared. Improved efficiencies (44%) and shorter response times were found by adding wetting agents and methanotic NaOH to the scintillation mixture in the filter paper. The scintillation chemicals used did not contain dioxane and were found to be nontoxic to the test microbiota in this system. Covering the inner reaction vial with aluminum foil minimized the reduction in counting efficiency when testing colored or dense environmenal samples. Mineralization rates were determined with 14 C-labeled glucose, acetate, and glutamate and [ 14 C]cellulose- and [ 14 C]lignin-labeled lignocellulose for composting cow manure, forest soil, and arctic lake sediment microbiota. This improved method can be used in a variety of procedures involving the measurement of microbial mineralizations of organic compounds. Since no liquid scintillation cocktail is used for counting, the radioactive wastes are aqueous or can be incinerated, making disposal easy

Impact of Vial Capping on Residual Seal Force and Container Closure Integrity.

Science.gov (United States)

Mathaes, Roman; Mahler, Hanns-Christian; Roggo, Yves; Ovadia, Robert; Lam, Philippe; Stauch, Oliver; Vogt, Martin; Roehl, Holger; Huwyler, Joerg; Mohl, Silke; Streubel, Alexander

2016-01-01

The vial capping process is a critical unit operation during drug product manufacturing, as it could possibly generate cosmetic defects or even affect container closure integrity. Yet there is significant variability in capping equipment and processes, and their relation to potential defects or container closure integrity has not been thoroughly studied. In this study we applied several methods-residual seal force tester, a self-developed system of a piezo force sensor measurement, and computed tomography-to characterize different container closure system combinations that had been sealed using different capping process parameter settings. Additionally, container closure integrity of these samples was measured using helium leakage (physical container closure integrity) and compared to characterization data. The different capping equipment settings lead to residual seal force values from 7 to 115 N. High residual seal force values were achieved with high capping pre-compression force and a short distance between the capping plate and plunge. The choice of container closure system influenced the obtained residual seal force values. The residual seal force tester and piezoelectric measurements showed similar trends. All vials passed physical container closure integrity testing, and no stopper rupture was seen with any of the settings applied, suggesting that container closure integrity was warranted for the studied container closure system with the chosen capping setting ranges. The vial capping process is a critical unit operation during drug product manufacturing, as it could possibly generate cosmetic defects or even affect container closure integrity. Yet there is significant variability in capping equipment and processes, and their relation to potential defects or container closure integrity has not been thoroughly studied. In this study we applied several methods-residual seal force tester, a self-developed system of a piezo force sensor measurement, and

Determination of the influence factors of the radiopharmaceutical vials dimensions used for activimeter calibration at IPEN

Energy Technology Data Exchange (ETDEWEB)

Martins, E.W. [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN), Avenida Professor Lineu Prestes, 2242, 05508-000 Sao Paulo, SP (Brazil); Potiens, M.P.A., E-mail: mppalbu@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN), Avenida Professor Lineu Prestes, 2242, 05508-000 Sao Paulo, SP (Brazil)

2012-07-15

This paper presents the establishment of a quality control program and correction factors for the geometry of the vials used for distribution of radiopharmaceutical and activimeters calibration. The radiopharmaceutical produced by IPEN {sup 67}Ga, {sup 131}I, {sup 201}Tl and {sup 99m}Tc had been tested using two different vials. Results show a maximum variation of 22% for {sup 201}Tl, and the minimum variation was 2.98% for {sup 131}I. The correction factors must be incorporated in the routine calibration of the activimeters. - Highlights: Black-Right-Pointing-Pointer Establishement of quality control program for reference activimeters. Black-Right-Pointing-Pointer Determination of correction factors for the geometry of vials. Black-Right-Pointing-Pointer Radiopharmaceuticals tested for different vials were {sup 67}Ga, {sup 131}I, {sup 201}Tl and {sup 99m}Tc. Black-Right-Pointing-Pointer The maximum variation was 22% for {sup 201}Tl and the minimum variation was 2.98% for {sup 131}I. Black-Right-Pointing-Pointer Correction factors must be incorporated in the calibration of the activimeters.

Investigation of factors affecting adhesion of 99Tcm labelled colloids to glass vials

International Nuclear Information System (INIS)

Elliott, A.T.; Murray, T.; Hilditch, T.E.; Whateley, T.L.

1990-01-01

Factors which may possibly influence the adhesion of 99 Tc m labelled colloid to glass vials were investigated. Of five colloids studied, two protein-free tin colloids were affected most by the problem, some 12-18% being lost by adhesion to the glass vial when the colloid was left resting on the bench, or 60-87% when it was rotated for a period of 4 h. The proportion of activity which adhered to the vial was dependent on the time the product had been contained within it, whether on the bench or rotated. Two of the colloids, both of which contained protein, were affected only slightly by the problem, one being a tin colloid and the other a sulphur colloid. An antimony sulphide colloid, which contained no added protein, was virtually unaffected by the problem. The degree of adhesion was not related to the pH of the product, or to the temperature at which the product was stored, nor to the tendency of the colloidal particles to grow in size upon vigorous agitation. (author)

Dissolution test for glibenclamide tablets

Directory of Open Access Journals (Sweden)

Elisabeth Aparecida dos Santos Gianotto

2007-10-01

Full Text Available The aim of this work is to develop and validate a dissolution test for glibenclamide tablets. Optimal conditions to carry out the dissolution test are 500 mL of phosphate buffer at pH 8.0, paddles at 75 rpm stirring speed, time test set to 60 min and using equipment with six vessels. The derivative UV spectrophotometric method for determination of glibenclamide released was developed, validated and compared with the HPLC method. The UVDS method presents linearity (r² = 0.9999 in the concentration range of 5-14 µg/mL. Precision and recoveries were 0.42% and 100.25%, respectively. The method was applied to three products commercially available on the Brazilian market.

Calculation methods for dissolution rate of multicomponent alloys during electrochemical machining

International Nuclear Information System (INIS)

Dikusar, A.I.; Petrenko, V.I.; Dikusar, G.K.; Ehngel'gardt, G.R.; Michukova, N.Yu.

1981-01-01

The possibility of theoretical calculation of metal dissolution rate during electrochemical mashining is considered. Two calculation techniques are compared at the example of two-component W-Re, Ni-W, Mo-Re alloys, namely: ''charge superposition'' and ''weight percents''. It is concluded that the technique of ''charge superposition'' is the only grounded calculation technique of specific rates of dissolution for alloys [ru

Dissolution of aluminium

International Nuclear Information System (INIS)

Uriarte Hueda, A.; Berberana Eizmendi, M.; Pereira Sanchez, G.

1968-01-01

The dissolution of aluminum with acid solutions ( nitric acid-mercuric nitrate) and alkaline solutions (sodium hydroxide-sodium nitrate) has been studied. The instantaneous dissolution rate (IDR) has been studied in function of the concentration of the used reagents and the dissolution temperature. The complete dissolution has been included in the second part of this report, to know the total dissolution time, the consume of reagents and the stability of the resultant solutions. (Author)

APIC position paper: Safe injection, infusion, and medication vial practices in health care.

Science.gov (United States)

Dolan, Susan A; Arias, Kathleen Meehan; Felizardo, Gwen; Barnes, Sue; Kraska, Susan; Patrick, Marcia; Bumsted, Amelia

2016-07-01

The transmission of bloodborne viruses and other microbial pathogens to patients during routine health care procedures continues to occur because of the use of improper injection, infusion, medication vial, and point-of-care testing practices by health care personnel. These unsafe practices occur in various clinical settings and result in unacceptable and devastating events for patients. This document updates the Association for Professionals in Infection Control and Epidemiology 2010 position paper on safe injection, infusion, and medication vial practices in health care. Copyright © 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Development and Validation of Discriminating and Biorelevant Dissolution Test for Lornoxicam Tablets.

Science.gov (United States)

Anumolu, P D; Sunitha, G; Bindu, S Hima; Satheshbabu, P R; Subrahmanyam, C V S

2015-01-01

The establishment of biorelevant and discriminating dissolution procedure for drug products with limited water solubility is a useful technique for qualitative forecasting of the in vivo behavior of formulations. It also characterizes the drug product performance in pharmaceutical development. Lornoxicam, a BCS class-II drug is a nonsteroidal antiinflammatory drug of the oxicam class, has no official dissolution media available in the literature. The objective of present work was to develop and validate a discriminating and biorelevant dissolution test for lornoxicam tablet dosage forms. To quantify the lornoxicam in dissolution samples, UV spectrophotometric method was developed using 0.01M sodium hydroxide solution as solvent at λma×376 nm. After evaluation of saturation solubility, dissolution, sink conditions and stability of lornoxicam bulk drug in different pH solutions and biorelevant media, the dissolution method was optimized using USP paddle type apparatus at 50 rpm rotation speed and 500 ml simulated intestinal fluid as discriminating and biorelevant dissolution medium. The similarity factor (f2) were investigated for formulations with changes in composition and manufacturing variations, values revealed that dissolution method having discriminating power and method was validated as per standard guidelines. The proposed dissolution method can be effectively applied for routine quality control in vitro dissolution studies of lornoxicam in tablets and helpful to pharmacopoeias.

Wastewater parameters after the process of phosphorus compounds removal by the metal dissolution method in comparison with precipitation and electrocoagulation methods

Directory of Open Access Journals (Sweden)

Wysocka Izabela

2017-03-01

Full Text Available Precipitation methods are commonly used for removing phosphorus compounds from wastewater. Chemical precipitation method, based on adding iron, aluminium or calcium salts to the treated wastewater, is often used. Another possible way of precipitating phosphates is metal dissolution method, which is presented in this paper. The main difference between these two methods is how the phosphate precipitating ions are introduced to the wastewater.

Aluminum elution and precipitation in glass vials: effect of pH and buffer species.

Science.gov (United States)

Ogawa, Toru; Miyajima, Makoto; Wakiyama, Naoki; Terada, Katsuhide

2015-02-01

Inorganic extractables from glass vials may cause particle formation in the drug solution. In this study, the ability of eluting Al ion from borosilicate glass vials, and tendencies of precipitation containing Al were investigated using various pHs of phosphate, citrate, acetate and histidine buffer. Through heating, all of the buffers showed that Si and Al were eluted from glass vials in ratios almost the same as the composition of borosilicate glass, and the amounts of Al and Si from various buffer solutions at pH 7 were in the following order: citrate > phosphate > acetate > histidine. In addition, during storage after heating, the Al concentration at certain pHs of phosphate and acetate buffer solution decreased, suggesting the formation of particles containing Al. In citrate buffer, Al did not decrease in spite of the high elution amount. Considering that the solubility profile of aluminum oxide and the Al eluting profile of borosilicate glass were different, it is speculated that Al ion may be forced to leach into the buffer solution according to Si elution on the surface of glass vials. When Al ions were added to the buffer solutions, phosphate, acetate and histidine buffer showed a decrease of Al concentration during storage at a neutral range of pHs, indicating the formation of particles containing Al. In conclusion, it is suggested that phosphate buffer solution has higher possibility of forming particles containing Al than other buffer solutions.

Jarosite dissolution rates in perchlorate brine

Science.gov (United States)

Legett, Carey; Pritchett, Brittany N.; Elwood Madden, Andrew S.; Phillips-Lander, Charity M.; Elwood Madden, Megan E.

2018-02-01

Perchlorate salts and the ferric sulfate mineral jarosite have been detected at multiple locations on Mars by both landed instruments and orbiting spectrometers. Many perchlorate brines have eutectic temperatures bearing rocks and sediments may have been altered by perchlorate brines. Here we measured jarosite dissolution rates in 2 M sodium perchlorate brine as well as dilute water at 298 K to determine the effects of perchlorate anions on jarosite dissolution rates and potential reaction products. We developed a simple method for determining aqueous iron concentrations in high salinity perchlorate solutions using ultraviolet-visible spectrophotometry that eliminates the risk of rapid oxidation reactions during analyses. Jarosite dissolution rates in 2 M perchlorate brine determined by iron release rate (2.87 × 10-12 ±0.85 × 10-12 mol m-2 s-1) were slightly slower than the jarosite dissolution rate measured in ultrapure (18.2 MΩ cm-1) water (5.06 × 10-12 mol m-2 s-1) using identical methods. No additional secondary phases were observed in XRD analyses of the reaction products. The observed decrease in dissolution rate may be due to lower activity of water (ɑH2O = 0.9) in the 2 M NaClO4 brine compared with ultrapure water (ɑH2O = 1). This suggests that the perchlorate anion does not facilitate iron release, unlike chloride anions which accelerated Fe release rates in previously reported jarosite and hematite dissolution experiments. Since dissolution rates are slower in perchlorate-rich solutions, jarosite is expected to persist longer in perchlorate brines than in dilute waters or chloride-rich brines. Therefore, if perchlorate brines dominate aqueous fluids on the surface of Mars, jarosite may remain preserved over extended periods of time, despite active aqueous processes.

Chemometrics-assisted spectrophotometric green method for correcting interferences in biowaiver studies: Application to assay and dissolution profiling study of donepezil hydrochloride tablets

Science.gov (United States)

Korany, Mohamed A.; Mahgoub, Hoda; Haggag, Rim S.; Ragab, Marwa A. A.; Elmallah, Osama A.

2018-06-01

A green, simple and cost effective chemometric UV-Vis spectrophotometric method has been developed and validated for correcting interferences that arise during conducting biowaiver studies. Chemometric manipulation has been done for enhancing the results of direct absorbance, resulting from very low concentrations (high incidence of background noise interference) of earlier points in the dissolution timing in case of dissolution profile using first and second derivative (D1 & D2) methods and their corresponding Fourier function convoluted methods (D1/FF& D2/FF). The method applied for biowaiver study of Donepezil Hydrochloride (DH) as a representative model was done by comparing two different dosage forms containing 5 mg DH per tablet as an application of a developed chemometric method for correcting interferences as well as for the assay and dissolution testing in its tablet dosage form. The results showed that first derivative technique can be used for enhancement of the data in case of low concentration range of DH (1-8 μg mL-1) in the three different pH dissolution media which were used to estimate the low drug concentrations dissolved at the early points in the biowaiver study. Furthermore, the results showed similarity in phosphate buffer pH 6.8 and dissimilarity in the other 2 pH media. The method was validated according to ICH guidelines and USP monograph for both assays (HCl of pH 1.2) and dissolution study in 3 pH media (HCl of pH 1.2, acetate buffer of pH 4.5 and phosphate buffer of pH 6.8). Finally, the assessment of the method greenness was done using two different assessment techniques: National Environmental Method Index label and Eco scale methods. Both techniques ascertained the greenness of the proposed method.

Análisis de la aplicación de una Auditoría de Seguridad Vial en carreteras concesionadas

OpenAIRE

Torres Márquez, Rolando Roque

2017-01-01

La tesis tiene como objetivo presentar y analizar la aplicación de una Auditoría de Seguridad Vial en un tramo de carretera concesionada ubicado al norte de la ciudad de Lima y que actualmente se encuentra en explotación. Para ello, se presentan los fundamentos conceptuales de la seguridad vial y la auditoría de Seguridad Vial acompañado de una breve explicación de los alcances y ventajas. Así mismo, se desarrollan las actividades que se ejecutaron en la auditoría y las actividades realizadas...

Robustness testing, using experimental design, of a flow-through dissolution method for a product where the actives have markedly differing solubility properties.

Science.gov (United States)

Bloomfield, M S; Butler, W C

2000-09-25

The use of experimental design for the robustness testing of a flow-through dissolution method (Ph Eur/USP Apparatus 4) for atovaquone, one of the drug substances in a dual-active anti-malarial tablet formulation, Malarone tablets, is described. This procedure was developed to overcome the suppression of the atovaquone solubility, caused by the presence of the co-drug proguanil hydrochloride and potential imprecision due to the poor solubility of the coating material in the basic dissolution media employed. For this testing a quarter fractional two-level factorial design was applied, assessing six factors in sixteen experiments, with a further six centre points to assess natural experimental variation. Results demonstrate that the method is robust to small changes in all the main factors evaluated at sample times of 30 min or greater. At 15 min, variations in the concentration of sodium hydroxide in the dissolution media, peristaltic pump speed and flow rate were assessed as statistically significant. This observation is a result of the initial steepness of the dissolution release curve and hence these factors are now controlled routinely in the method. Release of this poorly soluble drug is limited at the 45 min time point (Q=75%) according to pharmacopoeial guidelines. The approach may be applied for other dissolution procedures.

Study of the dissolution velocity of dispersed solid particles. Development of a calculation method for analyzing the kinetic curves. Extension to the study of composed kinetics

International Nuclear Information System (INIS)

Jorda, Michel.

1976-01-01

The dissolution of a solid in an aqueous phase is studied, the solid consisting of dispersed particles. A continuous colorimetric analysis method is developed to study the dissolution process and a two-parameter optimization method is established to investigate the kinetic curves obtained. This method is based on the differential equation dx/dt=K(1-x)sup(n). (n being the decrease in the dissolution velocity when the dissolved part increases and K a velocity parameter). The dissolution of SO 4 Cu and MnO 4 K in water and UO 3 in SO 4 H 2 is discussed. It is shown that the dissolution velocity of UO 3 is proportional to the concentration of the H + ions in the solution as far as this one is not higher than 0.25N. The study of the temperature dependence of the UO 3 dissolution reaction shows that a transition phase takes place from 25 to 65 0 C between a phase in which the dissolution is controlled by the diffusion of the H + ions and the chemical reaction at the interface and a phase in which the kinetics is only controlled by the diffusion [fr

Dissolution Model Development: Formulation Effects and Filter Complications

DEFF Research Database (Denmark)

Berthelsen, Ragna; Holm, Rene; Jacobsen, Jette

2016-01-01

This study describes various complications related to sample preparation (filtration) during development of a dissolution method intended to discriminate among different fenofibrate immediate-release formulations. Several dissolution apparatus and sample preparation techniques were tested. The fl....... With the tested drug–formulation combination, the best in vivo–in vitro correlation was found after filtration of the dissolution samples through 0.45-μm hydrophobic PTFE membrane filters....

Calcite Dissolution Kinetics

Science.gov (United States)

Berelson, W.; Subhas, A.; Dong, S.; Naviaux, J.; Adkins, J. F.

2016-12-01

A geological buffer for high atmospheric CO2 concentrations is neutralization via reaction with CaCO3. We have been studying the dissolution kinetics of carbonate minerals using labeled 13C calcite and Picarro-based measurements of 13C enrichments in solution DIC. This methodology has greatly facilitated our investigation of dissolution kinetics as a function of water carbonate chemistry, temperature and pressure. One can adjust the saturation state Omega by changing the ion activity product (e.g. adjusting carbonate ion concentration), or by changing the solubility product (e.g. adjusting temperature or pressure). The canonical formulation of dissolution rate vs. omega has been refined (Subhas et al. 2015) and shows distinct non-linear behavior near equilibrium and rates in sea water of 1-3 e-6 g/cm2day at omega = 0.8. Carbonic anhydrase (CA), an enzyme that catalyzes the hydration of dissolved CO2 to carbonic acid, was shown (in concentrations 500x. This result points to the importance of carbonic acid in enhancing dissolution at low degrees of undersaturation. CA activity and abundance in nature must be considered regarding the role it plays in catalyzing dissolution. We also have been investigating the role of temperature on dissolution kinetics. An increase of 16C yields an order of magnitude increase in dissolution rate. Temperature (and P) also change Omega critical, the saturation state where dissolution rates change substantially. Increasing pressure (achieved in a pressure reaction chamber we built) also shifts Omega critical closer to equilibrium and small pressure increases have large impact on dissolution kinetics. Dissolution rates are enhanced by an order of magnitude for a change in pressure of 1500 psi relative to the dissolution rate achieved by water chemistry effects alone for an omega of 0.8. We've shown that the thermodynamic determination of saturation state does not adequately describe the kinetics of dissolution. The interplay of mineral

Interactions between a poorly soluble cationic drug and sodium dodecyl sulfate in dissolution medium and their impact on in vitro dissolution behavior.

Science.gov (United States)

Huang, Zongyun; Parikh, Shuchi; Fish, William P

2018-01-15

In the pharmaceutical industry, in vitro dissolution testing ofsolid oral dosage forms is a very important tool for drug development and quality control. However, ion-pairing interaction between the ionic drugand surfactants in dissolution medium often occurs, resulting in inconsistent and incomplete drug release. The aim of this study is toevaluate the effects ofsodium dodecyl sulfate (SDS) mediated medium onthe dissolution behaviors of a poorly soluble cationic drug (Drug B). The study was carried out by measuring solubility of Drug B substance and dissolution rate of Drug B product in media containing SDS.Desolubilization of Drug B substance was observed at pH 4.5 in the presence of SDS at concentrations below critical micelle concentration (CMC) which is attributed to the formation of an insoluble di-dodecyl sulfate salt between SDS and Drug B. This ion-pairing effect is less significant with increasing medium pH where Drug B is less ionized and CMC of SDS is lower. In medium at pH 4.5, dissolution of Drug B product was found incomplete with SDS concentration below CMC due to the desolubilization of Drug B substance. In media with SDS level above CMC, the dissolution rate is rather slower with higher inter-vessel variations compared to that obtained in pH 4.5 medium without SDS. The dissolution results demonstrate that the presence of SDS in medium generates unexpected irregular dissolution profiles for Drug B which are attributed to incompatible dissolution medium for this particular drug. Therefore, non-ionic surfactant was selected for Drug B product dissolution method and ion-pairing effect in SDS mediated medium should be evaluated when developing a dissolution method for any poorly soluble cationic drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluación vial y plan de rehabilitación y mantenimiento de la vía Azogues- Cojitambo- Déleg- La Raya

OpenAIRE

Garcés Velecela, Diana Patricia

2017-01-01

Contar con una infraestructura vial adecuada permite el desarrollo de cualquier región. De ahí que el mantenimiento de la infraestructura vial es importante para garantizar el buen funcionamiento de la misma. Considerando que en nuestro país durante los últimos años se ha tenido una gran inversión en proyectos viales y muchos de ellos al no tener un adecuado mantenimiento presentan daños prematuros, es necesario, por lo tanto, realizar la evaluación vial y establecer un plan de rehabilitación...

Study and determination of the influence factors of the radiopharmaceutical vials dimensions used for actimeter calibration at IPEN

International Nuclear Information System (INIS)

Martins, Elaine Wirney

2010-01-01

The efficiency and safety of the nuclear medicine practice depend, among others factors, of a quality control programme, mainly related to the use of the nuclide activity meters (activimeter). One of the most important sources of errors in the activimeter measurements is the thickness, size and volume of the vial that contains the radiopharmaceutical considering that a typical activimeter has its response dependent of the vial used. The objective of this work was to establish a quality control programme and the correction factors for the geometry of the vials used for distribution of radiopharmaceutical and activimeters calibration, considering that the Calibration Laboratory of Instruments (LCI) of the Instituto de Pesquisas Energeticas e Nucleares (IPEN) has a NPL-CRC Secondary Standard Radionuclide Calibrator System, manufactured for the Southern Scientific plc, compound by an ionization chamber well type and a current measurement system, with traceability to National Physical Laboratory (NPL) and calibrated with a P6 vial type with different dimensions of the one used for the IPEN. The radiopharmaceutical produced by IPEN 67 Ga, '1 31 I, 201 Tl and 99 mTc, had been tested using the two different vials. The results shown a maximum variation of 22% for 201 Tl, and the minimum variation was 2.98% for 131 I. The correction factors must be incorporated in the routine calibration of the activimeters. (author)

Use of partial dissolution techniques in geochemical exploration

Science.gov (United States)

Chao, T.T.

1984-01-01

Application of partial dissolution techniques to geochemical exploration has advanced from an early empirical approach to an approach based on sound geochemical principles. This advance assures a prominent future position for the use of these techniques in geochemical exploration for concealed mineral deposits. Partial dissolution techniques are classified as single dissolution or sequential multiple dissolution depending on the number of steps taken in the procedure, or as "nonselective" extraction and as "selective" extraction in terms of the relative specificity of the extraction. The choice of dissolution techniques for use in geochemical exploration is dictated by the geology of the area, the type and degree of weathering, and the expected chemical forms of the ore and of the pathfinding elements. Case histories have illustrated many instances where partial dissolution techniques exhibit advantages over conventional methods of chemical analysis used in geochemical exploration. ?? 1984.

In vivo dissolution measurement with indium-111 summation peak ratios

International Nuclear Information System (INIS)

Jay, M.; Woodward, M.A.; Brouwer, K.R.

1985-01-01

Dissolution of [ 111 In]labeled tablets was measured in vivo in a totally noninvasive manner by using a modification of the perturbed angular correlation technique known as the summation peak ratio method. This method, which requires the incorporation of only 10-12 microCi into the dosage form, provided reliable dissolution data after oral administration of [ 111 In]lactose tablets. These results were supported by in vitro experiments which demonstrated that the dissolution rate as measured by the summation peak ratio method was in close agreement with the dissolution rate of salicylic acid in a [ 111 In]salicylic acid tablet. The method has the advantages of using only one detector, thereby avoiding the need for complex coincidence counting systems, requiring less radioactivity, and being potentially applicable to a gamma camera imaging system

CRITERIOS E INDICADORES DE SOSTENIBILIDAD EN EL SUBSECTOR VIAL

Directory of Open Access Journals (Sweden)

Martha Melizza Ordoñez Díaz

2015-01-01

Full Text Available Actualmente en Colombia el desempeño de un contratista de obra se determina de acuerdo con los avances y resultados obtenidos en la construcción de la misma, mas no por su desempeño ambiental; sin embargo, cualquier tipo de obra civil se puede llevar a cabo con mayor o menor complejidad, dependiendo de la disponibilidad de recursos naturales en la zona y la visión que tenga la comunidad sobre el proyecto, de tal forma que la inversión económica y el tiempo de ejecución no solo dependerá de las actividades y costos netos de las obras civiles sino, además, de factores ambientales y sociales propios del lugar de ejecución. Con esta revisión bibliográfica sobre indicadores y guías ambientales internacionales, se pretende incentivar la sostenibilidad como eje transversal de los proyectos viales en Colombia, fortalecer las medidas de manejo socioambiental y mejorar el seguimiento y evaluación de los proyectos viales en el marco del equilibrio social, ambiental y económico que impulsa el desarrollo sostenible

Solvent Removal and Spore Inactivation Directly in Dispensing Vials with Supercritical Carbon Dioxide and Sterilant

OpenAIRE

Howell, Jahna; Niu, Fengui; McCabe, Shannon E.; Zhou, Wei; Decedue, Charles J.

2012-01-01

A process is described using supercritical carbon dioxide to extract organic solvents from drug solutions contained in 30-mL serum vials. We report drying times of less than 1 h with quantitative recovery of sterile drug. A six-log reduction of three spore types used as biological indicators is achieved with direct addition of peracetic acid to a final concentration of approximately 5 mM (~0.04 %) to the drug solution in the vial. Analysis of two drugs, acetaminophen and paclitaxel, indicated...

Solid dispersions, part II: new strategies in manufacturing methods for dissolution rate enhancement of poorly water-soluble drugs.

Science.gov (United States)

Bikiaris, Dimitrios N

2011-12-01

The absorption of poorly water-soluble drugs, when presented in the crystalline state to the gastrointestinal tract, is typically dissolution rate-limited, and according to BCS these drugs belong mainly to class II. Both dissolution kinetics and solubility are particle size dependent. Nowadays, various techniques are available to the pharmaceutical industry for dissolution rate enhancement of such drugs. Among such techniques, nanosuspensions and drug formulation in solid dispersions are those with the highest interest. This review discusses strategies undertaken over the last 10 years, which have been applied for the dissolution enhancement of poorly water-soluble drugs; such processes include melt mixing, electrospinning, microwave irradiation and the use of inorganic nanoparticles. Many problems in this field still need to be solved, mainly the use of toxic solvents, and for this reason the use of innovative new procedures and materials will increase over the coming years. Melt mixing remains extremely promising for the preparation of SDs and will probably become the most used method in the future for the preparation of solid drug dispersions.

Protect Patients by Using Single- and Multi-Dose Vials Correctly

Centers for Disease Control (CDC) Podcasts

2014-07-10

CDC’s One & Only Campaign urges healthcare providers to recognize the differences between single-dose and multi-dose vials, and to understand appropriate use of each container type.  Created: 7/10/2014 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 7/10/2014.

Streamlined sample cleanup using combined dispersive solid-phase extraction and in-vial filtration for analysis of pesticides and environmental pollutants in shrimp

Science.gov (United States)

A new method of sample preparation was developed and is reported for the first time. The approach combines in-vial filtration with dispersive solid-phase extraction (d-SPE) in a fast and convenient cleanup of QuEChERS (quick, easy, cheap, effective, rugged, and safe) extracts. The method was appli...

Proteja a sus seres queridos de las lesiones viales

Centers for Disease Control (CDC) Podcasts

2008-12-10

Este podcast, que forma parte de la iniciativa Proteja a sus seres queridos, aborda las medidas que pueden tomar los padres de familia para ayudar a proteger a sus niños de las lesiones viales, una de las principales causas de lesiones infantiles.  Created: 12/10/2008 by National Center for Injury Prevention and Control (NCIPC).   Date Released: 4/1/2009.

Determination of geometry correction factors to different vials used to radiopharmaceutical activity measurements

International Nuclear Information System (INIS)

Kuahara, Lilian T.; Correa, Eduardo L.; Potiens, Maria da Penha A.

2015-01-01

The aim of this study is to present the geometry correction factors and their respective uncertainties to P6 and 10R vials and 3 mL and 5 mL plastic syringes using the reference activity meters present at the Laboratorio de Calibracao de Instrumentos (LCI), IPEN the secondary standard system Capintec NPL-CRC radionuclide calibrator, with traceability to the National Physics Laboratory (NPL), England and the work standard Capintec CRC-15BT and the Capintec CRC-25R. The procedure was made using 99m Tc, which is responsible for about 80 % of the routine procedures in a nuclear medicine service. Variations of up to 40 % between different vials using the same radionuclide were found. (author)

¡La calle también es mía! Los niños, las ciudades y la seguridad vial.

OpenAIRE

Alonso Plá, Francisco Manuel; Esteban Martínez, Cristina; Calatayud Miñana, Constanza; Alamar Rocatí, Beatriz

2009-01-01

El Instituto Universitario de Investigación en Tráfico y Seguridad Vial (INTRAS) y Attitudes (programa social de Audi), tras la publicación del libro "Los niños, las ciudades y la seguridad vial: una visión a partir de la investigación.", se plantearon como actividad complementaria la realización de unas jornadas que cumplieran los siguientes objetivos: • Permitir avanzar en el conocimiento y la implementación de medidas que contribuyan a una mejora de la seguridad vial en el caso concreto...

Vaccine vial stopper performance for fractional dose delivery of vaccines.

Science.gov (United States)

Jarrahian, Courtney; Myers, Daniel; Creelman, Ben; Saxon, Eugene; Zehrung, Darin

2017-07-03

Shortages of vaccines such as inactivated poliovirus and yellow fever vaccines have been addressed by administering reduced-or fractional-doses, as recommended by the World Health Organization Strategic Advisory Group of Experts on Immunization, to expand population coverage in countries at risk. We evaluated 3 kinds of vaccine vial stoppers to assess their performance after increased piercing from repeated withdrawal of doses needed when using fractional doses (0.1 mL) from presentations intended for full-dose (0.5 mL) delivery. Self-sealing capacity and fragmentation of the stopper were assessed via modified versions of international standard protocols. All stoppers maintained self-sealing capacity after 100 punctures. The damage to stoppers measured as the fragmentation rate was within the target of ≤ 10% of punctures resulting in a fragment after as many as 50 punctures. We concluded that stopper failure is not likely to be a concern if existing vaccine vials containing up to 10 regular doses are used up to 50 times for fractional dose delivery.

Influence of storage vial material on measurement of organophosphate flame retardant metabolites in urine.

Science.gov (United States)

Carignan, Courtney C; Butt, Craig M; Stapleton, Heather M; Meeker, John D; Minguez-Alarcón, Lidia; Williams, Paige L; Hauser, Russ

2017-08-01

Use of organophosphate flame retardants (PFRs) has increased over the past decade with the phase out of polybrominated diphenyl ethers. Urinary metabolites of PFRs are used as biomarkers of exposure in epidemiologic research, which typically uses samples collected and stored in polypropylene plastic cryovials. However, a small study suggested that the storage vial material may influence reported concentrations. Therefore, we aimed to examine the influence of the storage vial material on analytical measurement of PFR urinary metabolites. Using urine samples collected from participants in the Environment and Reproductive Health (EARTH) Study, we analyzed the PFR metabolites in duplicate aliquots that were stored in glass and plastic vials (n = 31 pairs). Bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), diphenyl phosphate (DPHP) and isopropyl-phenyl phenyl phosphate (ip-PPP) were detected in 98%, 97% and 87% of duplicates. We observed high correlations between glass-plastic duplicates for BDCIPP (r s  = 0.95), DPHP (r s  = 0.79) and ip-PPP (r s  = 0.82) (p samples stored in glass, with a mean relative difference of 14%. While this difference is statistically significant, it is small in magnitude. No differences were observed for BDCIPP or DPHP, however future research should seek to reduce the potential for type II error (false negatives). We conclude that storing urine samples in polypropylene plastic cryovials may result in slightly reduced concentrations of urinary ip-PPP relative to storage in glass vials and future research should seek to increase the sample size, reduce background variability and consider the material of the urine collection cup. Copyright © 2017 Elsevier Ltd. All rights reserved.

Size distributions of micro-bubbles generated by a pressurized dissolution method

Science.gov (United States)

Taya, C.; Maeda, Y.; Hosokawa, S.; Tomiyama, A.; Ito, Y.

2012-03-01

Size of micro-bubbles is widely distributed in the range of one to several hundreds micrometers and depends on generation methods, flow conditions and elapsed times after the bubble generation. Although a size distribution of micro-bubbles should be taken into account to improve accuracy in numerical simulations of flows with micro-bubbles, a variety of the size distribution makes it difficult to introduce the size distribution in the simulations. On the other hand, several models such as the Rosin-Rammler equation and the Nukiyama-Tanazawa equation have been proposed to represent the size distribution of particles or droplets. Applicability of these models to the size distribution of micro-bubbles has not been examined yet. In this study, we therefore measure size distribution of micro-bubbles generated by a pressurized dissolution method by using a phase Doppler anemometry (PDA), and investigate the applicability of the available models to the size distributions of micro-bubbles. Experimental apparatus consists of a pressurized tank in which air is dissolved in liquid under high pressure condition, a decompression nozzle in which micro-bubbles are generated due to pressure reduction, a rectangular duct and an upper tank. Experiments are conducted for several liquid volumetric fluxes in the decompression nozzle. Measurements are carried out at the downstream region of the decompression nozzle and in the upper tank. The experimental results indicate that (1) the Nukiyama-Tanasawa equation well represents the size distribution of micro-bubbles generated by the pressurized dissolution method, whereas the Rosin-Rammler equation fails in the representation, (2) the bubble size distribution of micro-bubbles can be evaluated by using the Nukiyama-Tanasawa equation without individual bubble diameters, when mean bubble diameter and skewness of the bubble distribution are given, and (3) an evaluation method of visibility based on the bubble size distribution and bubble

Testing of the Defense Waste Processing Facility Cold Chemical Dissolution Method in Sludge Batch 9 Qualification

Energy Technology Data Exchange (ETDEWEB)

Edwards, T. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Pareizs, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Coleman, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Young, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Brown, L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2016-05-10

For each sludge batch that is processed in the Defense Waste Processing Facility (DWPF), the Savannah River National Laboratory (SRNL) tests the applicability of the digestion methods used by the DWPF Laboratory for elemental analysis of Sludge Receipt and Adjustment Tank (SRAT) Receipt samples and SRAT Product process control samples. DWPF SRAT samples are typically dissolved using a method referred to as the DWPF Cold Chemical or Cold Chem Method (CC), (see DWPF Procedure SW4- 15.201). Testing indicates that the CC method produced mixed results. The CC method did not result in complete dissolution of either the SRAT Receipt or SRAT Product with some fine, dark solids remaining. However, elemental analyses did not reveal extreme biases for the major elements in the sludge when compared with analyses obtained following dissolution by hot aqua regia (AR) or sodium peroxide fusion (PF) methods. The CC elemental analyses agreed with the AR and PF methods well enough that it should be adequate for routine process control analyses in the DWPF after much more extensive side-by-side tests of the CC method and the PF method are performed on the first 10 SRAT cycles of the Sludge Batch 9 (SB9) campaign. The DWPF Laboratory should continue with their plans for further tests of the CC method during these 10 SRAT cycles.

Etching of semiconductor cubic crystals: Determination of the dissolution slowness surfaces

Science.gov (United States)

Tellier, C. R.

1990-03-01

Equations of the representative surface of dissolution slowness for cubic crystals are determined in the framework of a tensorial approach of the orientation-dependent etching process. The independent dissolution constants are deduced from symmetry considerations. Using previous data on the chemical etching of germanium and gallium arsenide crystals, some possible polar diagrams of the dissolution slowness are proposed. A numerical and graphical simulation method is used to obtain the derived dissolution shapes. The influence of extrema in the dissolution slowness on the successive dissolution shapes is also examined. A graphical construction of limiting shapes of etched crystals appears possible using the tensorial representation of the dissolution slowness.

A quality improvement project to reduce the intraoperative use of single-dose fentanyl vials across multiple patients in a pediatric institution.

Science.gov (United States)

Buck, David; Subramanyam, Rajeev; Varughese, Anna

2016-01-01

The use of a single-dose vial across multiple patients presents a risk to sterility and is against CDC guidelines. We initiated a quality improvement (QI) project to reduce the intraoperative use of single-dose vials of fentanyl across multiple patients at Cincinnati Children's Hospital Medical Center (CCHMC). The initial step of the improvement project was the development of a Key Driver Diagram. The diagram has the SMART aim of the project, key drivers inherent to the process we are trying to improve, and specific interventions targeting the key drivers. The number of patients each week receiving an IV dose of fentanyl, from a vial previously accessed for another patient was tracked in a high turnover operating room (OR). The improvement model used was based on the concept of building Plan-Do-Study-Act (PDSA) cycles. Tests of change included provider education, provision of an increased number of fentanyl vials, alternate wasting processes, and provision of single-use fentanyl syringes by the pharmacy. Prior to initiation of this project, it was common for a single fentanyl vial to be accessed for multiple patients. Our data showed an average percentage of failures of just over 50%. During the end of the project, after 7 months, the mean percentage failures had dropped to 5%. Preparation of 20 mcg single-use fentanyl syringes by pharmacy, combined with education of providers on appropriate use, was successful in reducing failures to below our goal of 25%. Appropriately sized fentanyl syringes prepared by pharmacy, education on correct use of single-dose vials, and reminders in the OR, reduced the percentage of patients receiving a dose of fentanyl from a vial previously accessed for another patient in a high-volume otolaryngology room. © 2015 John Wiley & Sons Ltd.

Chemoinformetrical evaluation of dissolution property of indomethacin tablets by near-infrared spectroscopy.

Science.gov (United States)

Otsuka, Makoto; Tanabe, Hideaki; Osaki, Kazuo; Otsuka, Kuniko; Ozaki, Yukihiro

2007-04-01

The purpose of this study was to use near-infrared spectrometry (NIR) with chemoinformetrics to predict the change of dissolution properties in indomethacin (IMC) tablets during the manufacturing process. A comparative evaluation of the dissolution properties of the tablets was performed by the diffused reflectance (DRNIR) and transmittance (TNIR) NIR spectroscopic methods. Various kinds of IMC tablets (200 mg) were obtained from a powder (20 mg of IMC, 18 mg of microcrystalline cellulose, 160 mg of lactose, and 2 mg of magnesium stearate) under various compression pressures (60-398 MPa). Dissolution tests were performed in phosphate buffer, and the time required for 75% dissolution (T75) and mean dissolution time (MDT) were calculated. DRNIR and TNIR spectra were recorded, and the both NIR spectra used to establish a calibration model for predicting the dissolution properties by principal component regression analysis (PCR). The T75 and MDT increased as the compression pressure increased, since tablet porosity decreased with increasing pressure. Intensity of the DRNIR spectra of the compressed tablets decreased as the compression pressure increased. However, the intensity of TNIR spectra increased along with the pressure. The calibration models used to evaluate the dissolution properties of tablets were established by using PCR based on both DRNIR and TNIR spectra of the tablets. The multiple correlation coefficients of the relationship between the actual and predictive T75 by the DRNIR and TNIR methods were 0.831 and 0.962, respectively. It is possible to predict the dissolution properties of pharmaceutical preparations using both DRNIR and TNIR chemoinformetric methods. The TNIR method was more accurate for predictions of the dissolution behavior of tablets than the DRNIR method. (c) 2007 Wiley-Liss, Inc.

Criticality safety in high explosives dissolution

International Nuclear Information System (INIS)

Troyer, S.D.

1997-01-01

In 1992, an incident occurred at the Pantex Plant in which the cladding around a fissile material component (pit) cracked during dismantlement of the high explosives portion of a nuclear weapon. Although the event did not result in any significant contamination or personnel exposures, concerns about the incident led to the conclusion that the current dismantlement process was unacceptable. Options considered for redesign, dissolution tooling design considerations, dissolution tooling design features, and the analysis of the new dissolution tooling are summarized. The final tooling design developed incorporated a number of safety features and provides a simple, self-contained, low-maintenance method of high explosives removal for nuclear explosive dismantlement. Analyses demonstrate that the tooling design will remain subcritical under normal, abnormal, and credible accident scenarios. 1 fig

In vitro Dissolution Studies on Solid Dispersions of Mefenamic Acid.

Science.gov (United States)

Rao, K R S Sambasiva; Nagabhushanam, M V; Chowdary, K P R

2011-03-01

Solid dispersions of mefanamic acid with a water-soluble polymer polyvinyl pyrrolidine and a super disintegrant, primojel were prepared by common solvent and solvent evaporation methods employing methanol as the solvent. The dissolution rate and dissolution efficiency of the prepared solid dispersions were evaluated in comparison to the corresponding pure drug. Solid dispersions of mefenamic acid showed a marked enhancement in dissolution rate and dissolution efficiency. At 1:4 ratio of mefenamic acid-primojel a 2.61 fold increase in the dissolution rate of mefenamic acid was observed with solid dispersion. The solid dispersions in combined carriers gave much higher rates of dissolution than super disintegrants alone. Mefanamic acid-primojel-polyvinyl pyrrolidine (1:3.2:0.8) solid dispersion gave a 4.11 fold increase in the dissolution rate of mefenamic acid. Super disintegrants alone or in combination with polyvinyl pyrrolidine could be used to enhance the dissolution rate of mefenamic acid.

Dissolution of mixed oxide spent fuel from FBR

International Nuclear Information System (INIS)

Sanyoshi, H.; Nishina, H.; Toyota, O.; Yamamoto, R.; Nemoto, S.; Okamoto, F.; Togashi, A.; Kawata, T.; Hayashi, S.

1991-01-01

At the Tokai Works of the Power Reactor and Nuclear Fuel Development Corporation (PNC), the Chemical Processing Facility (CPF) has been continuing operation since 1982 for laboratory scale hot experiments on reprocessing of FBR mixed oxide fuel. As a part of these experiments, dissolution experiments have been performed to define the key parameters affecting dissolution rates such as concentration of nitric acid, temperature and burnup and also to confirm the amount of insoluble residue. The dissolution rate of the irradiated fuel was determined to be in proportion to the 1.7 power of the nitric acid concentration. The activation energy determined from the experiments varied from 6 to 11 kcal/mol depending on the method of dissolution. The dissolution rate decreased as the fuel burnup increased in low nitric acid media below 5 mol/l. However, it was found that the effect of the burnup became negligible in a high concentration of nitric acid media. The amount of insoluble residue and its constituents were evaluated by changing the dissolution condition. (author)

Measurement of micro Bubbles generated by a pressurized dissolution method

Energy Technology Data Exchange (ETDEWEB)

Hosokawa, S; Tanaka, K; Tomiyama, A [Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501 (Japan); Maeda, Y; Yamaguchi, S; Ito, Y, E-mail: hosokawa@mech.kobe-u.ac.j [Panasonic Electric Works Co., Ltd., 1048 Kadoma, Osaka 571-8686 (Japan)

2009-02-01

Diameters of micro-bubbles are apt to range from about one mm to several-hundred mm, and therefore, it is difficult to measure a correct diameter distribution using a single measurement method. In this study, diameters of bubbles generated by a pressurized dissolution method are measured by using phase Doppler anemometry (PDA) and an image processing method, which is based on the Sobel filter and Hough transform. The diameter distribution and the Sauter mean diameter of micro bubbles are evaluated based on the diameters measured by both methods. Experiments are conducted for several mass flow rates of dissolved gas and of air bubbles entrained in the upstream of the decompression nozzle to examine effects of the entrained bubbles on bubble diameter. As a result, the following conclusions are obtained: (1) Diameter distribution of micro bubbles can be accurately measured for a wide range of diameter by using PDA and the image processing method. (2) The mean diameter of micro-bubbles generated by gasification of dissolved gas is smaller than that generated by breakup of air bubbles entrained in the upstream of the decompression nozzle. (3) The mean bubble diameter increases with the entrainment of air bubbles in the upstream of the decompression nozzle at a constant mass flow rate of dissolved gas.

Measurement of micro Bubbles generated by a pressurized dissolution method

International Nuclear Information System (INIS)

Hosokawa, S; Tanaka, K; Tomiyama, A; Maeda, Y; Yamaguchi, S; Ito, Y

2009-01-01

Diameters of micro-bubbles are apt to range from about one mm to several-hundred mm, and therefore, it is difficult to measure a correct diameter distribution using a single measurement method. In this study, diameters of bubbles generated by a pressurized dissolution method are measured by using phase Doppler anemometry (PDA) and an image processing method, which is based on the Sobel filter and Hough transform. The diameter distribution and the Sauter mean diameter of micro bubbles are evaluated based on the diameters measured by both methods. Experiments are conducted for several mass flow rates of dissolved gas and of air bubbles entrained in the upstream of the decompression nozzle to examine effects of the entrained bubbles on bubble diameter. As a result, the following conclusions are obtained: (1) Diameter distribution of micro bubbles can be accurately measured for a wide range of diameter by using PDA and the image processing method. (2) The mean diameter of micro-bubbles generated by gasification of dissolved gas is smaller than that generated by breakup of air bubbles entrained in the upstream of the decompression nozzle. (3) The mean bubble diameter increases with the entrainment of air bubbles in the upstream of the decompression nozzle at a constant mass flow rate of dissolved gas.

Determination of the influence factors of the radiopharmaceutical vials dimensions used for activimeter calibration at IPEN.

Science.gov (United States)

Martins, E W; Potiens, M P A

2012-07-01

This paper presents the establishment of a quality control program and correction factors for the geometry of the vials used for distribution of radiopharmaceutical and activimeters calibration. The radiopharmaceutical produced by IPEN 67Ga, 131I, 201Tl and 99mTc had been tested using two different vials. Results show a maximum variation of 22% for 201Tl, and the minimum variation was 2.98% for 131I. The correction factors must be incorporated in the routine calibration of the activimeters. Copyright © 2011 Elsevier Ltd. All rights reserved.

Solubility limits on radionuclide dissolution

Energy Technology Data Exchange (ETDEWEB)

Kerrisk, J.F.

1984-12-31

This paper examines the effects of solubility in limiting dissolution rates of a number of important radionuclides from spent fuel and high-level waste. Two simple dissolution models were used for calculations that would be characteristics of a Yucca Mountain repository. A saturation-limited dissolution model, in which the water flowing through the repository is assumed to be saturated with each waste element, is very conservative in that it overestimates dissolution rates. A diffusion-limited dissolution model, in which element-dissolution rates are limited by diffusion of waste elements into water flowing past the waste, is more realistic, but it is subject to some uncertainty at this time. Dissolution rates of some elements (Pu, Am, Sn, Th, Zr, Sm) are always limited by solubility. Dissolution rates of other elements (Cs, Tc, Np, Sr, C, I) are never solubility limited; their release would be limited by dissolution of the bulk waste form. Still other elements (U, Cm, Ni, Ra) show solubility-limited dissolution under some conditions. 9 references, 3 tables.

Influence of initial temperature and heating method in the temperature profile during alkaline dissolution of Al for the production of Mo-99

Energy Technology Data Exchange (ETDEWEB)

Camilo, Ruth L.; Araujo, Izilda C.; Mindrisz, Ana C.; Forbicini, Christina A.L.G. de O., E-mail: rcamilo@ipen.br, E-mail: cruzaraujo22@gmail.com, E-mail: acmindri@ipen.br, E-mail: cforbici@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2013-07-01

Radionuclides in nuclear medicine can be used for diagnosis and therapy. The {sup 99m}Tc, son of {sup 99}Mo, is most often used in nuclear medicine as tracer element because of its favorable nuclear properties, accounting for about 80% of all diagnostic procedures in vivo. Aiming to resolve the dependency of Brazil with respect to the supply of {sup 99}Mo was created the Brazilian Multipurpose Reactor project (BMR), started in 2008, having as main objective to produce about 1000 Ci/week of {sup 99}Mo. This study is part of the project to obtain {sup 9}'9Mo by alkaline dissolution of UAl{sub x}-Al targets. The initial reaction temperature is an important parameter, since it has great influence on the value of the maximum temperature and dissolution time. According to literature, for security reasons the dissolution process must have its temperature controlled so that the maximum temperature has to be around 90 deg C. The behavior of the temperature during dissolution using three different methods of heating in order to minimize the fluctuation of temperature during dissolution, keeping its maximum value at around 90 deg C was studied. The three methods of heating chosen were: a) initial temperature of 85 deg C with continuous heating, b) heating water bath until it reaches the initial temperature (70 to 95 deg C), turning off after that, and c) external heating until it reached the starting temperature (60-95 deg C). The alkaline solution used was 3 mol.L{sup -1} NaOH{sub 3} and 2 mol.L{sup -1} NaNO{sub 3}. In the first study it was observed that after 1 minute of dissolution the solution temperature reached 100 deg C on average, up to a maximum of 109 deg C, ending with values around 95 deg C. In the second study after 3 minutes of dissolution the maximum temperature was 106 deg C and the minimum 100 deg C. In the third study the temperature rise during dissolution increased with increasing initial temperature which practically remains constant until the end

An HPLC method for the determination of digoxin in dissolution samples

Directory of Open Access Journals (Sweden)

Milenković Miroslav Ž.

2010-01-01

Full Text Available An HPLC method for digoxin quantification in dissolution samples obtained as per the official British Pharmacopeia (BP method is presented in this paper. The chromatography was performed at 20 °C on a Symmetry C18; 3.5 ìm, 75 x 4.6 mm column with water - acetonitrile (72 : 28, v/v, as the mobile phase and UV detection at 220 nm. The method was found to be selective, linear, accurate and precise in the specified ranges. The LOD and LOQ were 0.015 μg mL-1 and 0.050 μg mL-1, respectively. Robustness testing was conducted to evaluate the impact of minor changes in the chromatographic parameters (i.e., acetonitrile fraction, flow rate of the mobile phase, column temperature and column length on the characteristics of the digoxin peak. A. full factorial design (24 was used to investigate the influence of the four variables The presented HPLC method was applied in quality and stability testing of Digoxin tablets 0.25 mg.

A Shandon PapSpin liquid-based gynecological test: A split-sample and direct-to-vial test with histology follow-up study

Directory of Open Access Journals (Sweden)

Rimiene J

2010-01-01

Full Text Available Background: Studies for liquid-based Papanicolaou (Pap tests reveal that liquid-based cytology (LBC is a safe and effective alternative to the conventional Pap smear. Although there is research on ThinPrep and SurePath systems, information is lacking to evaluate the efficiency and effectiveness of systems based on cytocentrifugation. This study is designed to determine the sensitivity and specificity of the Shandon PapSpin (ThermoShandon, Pittsburgh, Pennsylvania, USA liquid-based gynecological system. We used split-sample and direct-to-vial study design. Materials and Methods: 2,945 women referred to prophylactic check-up were enrolled in this study. Split sample design was used in 1,500 women and residual cervical cytology specimen from all these cases was placed in fluid for PapSpin preparation after performing conventional smear. The direct-to-vial study was carried out in another cohort of 1,445 women in whom the entire cervical material was investigated using only the PapSpin technique. Follow up histological diagnoses for 141 women were obtained from both study arms following 189 abnormal cytology cases. 80 LBC cases from the split sample group and 61 LBC cases in the direct-to-vial group were correlated with the histology results. The sensitivity and secificity of the conventional smear and PapSpin tests in both study arms were compared. Results: In the split sample group, conventional smears showed a higher proportion of ASC-US (atypical cells undetermined significance: 31 (2.1% vs 10 (0.7% in PapSpin (P = 0.001. A higher proportion of unsatisfactory samples was found in the conventional smear group: 25 (1.7% vs 6 (0.4% cases (P = 0.001. In the split sample group, the sensitivity of the conventional and PapSpin tests was 68.7% vs 78.1%, and the specificity 93.8% vs 91.8%, respectively. In the direct to vial group PapSpin sensitivity was 75.9% and specificity 96.5%. The differences in sensitivity and specificity were not significant. The

Dissolution process analysis using model-free Noyes-Whitney integral equation.

Science.gov (United States)

Hattori, Yusuke; Haruna, Yoshimasa; Otsuka, Makoto

2013-02-01

Drug dissolution process of solid dosages is theoretically described by Noyes-Whitney-Nernst equation. However, the analysis of the process is demonstrated assuming some models. Normally, the model-dependent methods are idealized and require some limitations. In this study, Noyes-Whitney integral equation was proposed and applied to represent the drug dissolution profiles of a solid formulation via the non-linear least squares (NLLS) method. The integral equation is a model-free formula involving the dissolution rate constant as a parameter. In the present study, several solid formulations were prepared via changing the blending time of magnesium stearate (MgSt) with theophylline monohydrate, α-lactose monohydrate, and crystalline cellulose. The formula could excellently represent the dissolution profile, and thereby the rate constant and specific surface area could be obtained by NLLS method. Since the long time blending coated the particle surface with MgSt, it was found that the water permeation was disturbed by its layer dissociating into disintegrant particles. In the end, the solid formulations were not disintegrated; however, the specific surface area gradually increased during the process of dissolution. The X-ray CT observation supported this result and demonstrated that the rough surface was dominant as compared to dissolution, and thus, specific surface area of the solid formulation gradually increased. Copyright © 2012 Elsevier B.V. All rights reserved.

Influência do tamanho do frasco de tuberculina nos resultados da prova tuberculínica Influence of vial size on the results of the tuberculin test

Directory of Open Access Journals (Sweden)

Antonio Ruffino-Netto

2005-04-01

Full Text Available INTRODUÇÃO: A solução de tuberculina é armazenada em frascos de diferentes tamanhos. Sua adsorção ao frasco pode influenciar o resultado da prova tuberculínica. OBJETIVO: Avaliar o efeito do tamanho do frasco de armazenamento da tuberculina nos resultados obtidos na prova tuberculínica. MÉTODO: Sessenta e três pacientes internados com diagnóstico de tuberculose ativa foram submetidos a duas provas tuberculínicas simultâneas, em ambos os antebraços. A técnica usada foi a de Mantoux e consistiu na aplicação de 0,1 ml de tuberculina armazenada em frascos de 5 ml ou de 1,5 ml, no antebraço direito e no antebraço esquerdo, de forma aleatória. A leitura da induração foi efetuada de forma cega por um único leitor treinado previamente. As leituras com diferenças de até 2 mm foram consideradas resultados concordantes. RESULTADOS: Vinte e um pacientes não tiveram induração e foram excluídos da análise. Entre os 42 pacientes restantes, a média dos diâmetros das indurações obtidas nas provas com tuberculina armazenada nos frascos grandes foi maior do que as obtidas com a armazenada em frascos pequenos. A concordância entre as leituras foi obtida em 40,5% delas (17/42, e a diferença foi negativa (frasco grande menor que frasco pequeno em 16,7% (7/42 e positiva em 42,9% delas (18/42. CONCLUSÃO: O tamanho do frasco de armazenamento da tuberculina pode influenciar o resultado da prova tuberculínica. A adsorção da tuberculina à parede do frasco pode explicar o fenômeno. Os autores alertam para o impacto dessas variações nos estudos epidemiológicos e operacionais.BACKGROUND: Tuberculin purified protein derivative is stored in vials of various sizes. Its adsorption to the vial can influence the results of tuberculin tests. OBJECTIVE: To evaluate the effect of vial size on the results obtained in tuberculin tests. METHODS: Sixty-four inpatients with active tuberculosis were submitted to two simultaneous tuberculin tests

Time-to-positivity, type of culture media and oxidase test performed on positive blood culture vials to predict Pseudomonas aeruginosa in patients with Gram-negative bacilli bacteraemia.

Science.gov (United States)

Cobos-Triguero, N; Zboromyrska, Y; Morata, L; Alejo, I; De La Calle, C; Vergara, A; Cardozo, C; Arcas, M P; Soriano, A; Marco, F; Mensa, J; Almela, M; Martínez, J A

2017-02-01

The aim of this study was to determine the usefulness of oxidase test and time-to-positivity (TTP) in aerobic and anaerobic blood culture vials to detect the presence of Pseudomonas aeruginosa in patients with Gram-negative bacilli (GNB) bacteraemia. TTP was recorded for each aerobic and anaerobic blood culture vial of monomicrobial bacteraemia due to GNB. Oxidase test was performed in a pellet of the centrifuged content of the positive blood culture. An algorithm was developed in order to perform the oxidase test efficiently taking into account TTP and type of vial. A total of 341 episodes of GNB bacteraemia were analysed. Sensitivity, specificity, positive predictive value and negative predictive value of the oxidase test performed on positive vials with GNB to predict P. aeruginosa were 95%, 99%, 91%, and 99%, respectively. When growth was first or exclusively detected in anaerobic vials, P. aeruginosa was never identified hence the performance of the oxidase test could be avoided. When growth was only or first detected in aerobic vials, a TTP≥8h predicted P. aeruginosa in 37% or cases (63 of 169), therefore oxidase test is highly recommended. Oxidase test performed onto positive blood culture vials previously selected by TTP and type of vials is an easy and inexpensive way to predict P. aeruginosa. In most cases, this can lead to optimization of treatment in less than 24 hours.

Vial usage, device dead space, vaccine wastage, and dose accuracy of intradermal delivery devices for inactivated poliovirus vaccine (IPV).

Science.gov (United States)

Jarrahian, Courtney; Rein-Weston, Annie; Saxon, Gene; Creelman, Ben; Kachmarik, Greg; Anand, Abhijeet; Zehrung, Darin

2017-03-27

Intradermal delivery of a fractional dose of inactivated poliovirus vaccine (IPV) offers potential benefits compared to intramuscular (IM) delivery, including possible cost reductions and easing of IPV supply shortages. Objectives of this study were to assess intradermal delivery devices for dead space, wastage generated by the filling process, dose accuracy, and total number of doses that can be delivered per vial. Devices tested included syringes with staked (fixed) needles (autodisable syringes and syringes used with intradermal adapters), a luer-slip needle and syringe, a mini-needle syringe, a hollow microneedle device, and disposable-syringe jet injectors with their associated filling adapters. Each device was used to withdraw 0.1-mL fractional doses from single-dose IM glass vials which were then ejected into a beaker. Both vial and device were weighed before and after filling and again after expulsion of liquid to record change in volume at each stage of the process. Data were used to calculate the number of doses that could potentially be obtained from multidose vials. Results show wide variability in dead space, dose accuracy, overall wastage, and total number of doses that can be obtained per vial among intradermal delivery devices. Syringes with staked needles had relatively low dead space and low overall wastage, and could achieve a greater number of doses per vial compared to syringes with a detachable luer-slip needle. Of the disposable-syringe jet injectors tested, one was comparable to syringes with staked needles. If intradermal delivery of IPV is introduced, selection of an intradermal delivery device can have a substantial impact on vaccine wasted during administration, and thus on the required quantity of vaccine that needs to be purchased. An ideal intradermal delivery device should be not only safe, reliable, accurate, and acceptable to users and vaccine recipients, but should also have low dead space, high dose accuracy, and low overall

Dissolution of nuclear fuels; Disolucion de combustibles Nucleares

Energy Technology Data Exchange (ETDEWEB)

Uriarte Hueda, A; Berberana Eizmendi, M; Rainey, R

1968-07-01

A laboratory study was made of the instantaneous dissolution rate (IDR) for unirradiated uranium metal rods and UO{sub 2}, PuO{sub 2} and PuO{sub 2}-UO{sub 2} pellets in boiling nitric acid alone and with additives. The uranium metal and UO{sub 2} dissolved readily in nitric acid alone; PuO{sub 2} dissolved slowly even with the addition of fluoride; PuO{sub 2}-UO{sub 2} pellets containing as much as 35% PuO{sub 2} in UO{sub 2} gave values of the instantaneous dissolution rate to indicate can be dissolved with nitric acid alone. An equation to calculate the time for complete dissolution has been determinate in function of the instantaneous dissolution rates. The calculated values agree with the experimental. Uranium dioxide pellets from various sources but all having a same density varied in instantaneous dissolution rate. All the pellets, however, have dissolved ved in the same time. The time for complete dissolution of PuO{sub 2}-UO{sub 2} pellets, having the same composition, and the concentration of the used reagents are function of the used reagents are function of the fabrication method. (Author) 8 refs.

La Eficacia Publicitaria en las Campañas de Prevención para la Seguridad Vial

OpenAIRE

Serrano Cordero, Julia Catalina; Arévalo Peña, José David

2017-01-01

Este artículo aborda la importancia de los procesos de evaluación de los resultados en las campañas de educación y seguridad vial, éstos, si bien, han alcanzado notables progresos en la praxis, evidencian una falta de información en cuanto a la pertinencia e idoneidad de las herramientas de comunicación en prevención. El objetivo fue validar una campaña de educación y seguridad vial implementada por la Empresa Municipal de Tránsito y Transporte de la ciudad de Cuenca (Ecuador), en el año 2014...

The impact of calcium carbonate as pore forming agent and drug entrapment method towards drug dissolution mechanism of amoxicillin trihydrate encapsulated by chitosan-methyl cellulose semi-IPN hydrogel for floating drug delivery system

Science.gov (United States)

Dewantara, Fauzi; Budianto, Emil

2018-04-01

Chitosan-methyl cellulose semi-IPN hydrogel is used as floating drug delivery system, and calcium carbonate also added as pore forming agent. The hydrogel network arranged by not only using biopolymer chitosan and methyl cellulose, but also the crosslink agent that is glutaraldehyde. Amoxicillin trihydrate entrapped into the polymer network with two different method, in situ loading and post loading. Furthermore both method has been tested for drug entrapment efficiency along with drug dissolution test, and the result for drug entrapment efficiency is in situ loading method has highest value of 100%, compared to post loading method which has value only 71%. Moreover, at the final time of drug dissolution test shows in situ loading method has value of 96% for total accumulative of drug dissolution, meanwhile post loading method has 72%. The value of drug dissolution test from both method is used for analyzing drug dissolution mechanism of amoxicillin trihydrate from hydrogel network with four mathematical drug mechanism models as parameter. The polymer network encounter destructive degradation causes by acid solution which used as dissolution medium, and the level of degradation is observed with optical microscope. However the result shows that degradation of the polymer network doesn't affect drug dissolution mechanism directly. Although the pore forming agent causes the pore inside the hydrogel network create interconnection and it was quite influential to drug dissolution mechanism. Interconnected pore is observed with Scanning Electron Microscope (SEM) and shows that the amount and area of interconnected pore inside the hydrogel network is increasing as drug dissolution goes on.

The Use of Artificial Neural Network for Prediction of Dissolution Kinetics

Directory of Open Access Journals (Sweden)

H. Elçiçek

2014-01-01

Full Text Available Colemanite is a preferred boron mineral in industry, such as boric acid production, fabrication of heat resistant glass, and cleaning agents. Dissolution of the mineral is one of the most important processes for these industries. In this study, dissolution of colemanite was examined in water saturated with carbon dioxide solutions. Also, prediction of dissolution rate was determined using artificial neural networks (ANNs which are based on the multilayered perceptron. Reaction temperature, total pressure, stirring speed, solid/liquid ratio, particle size, and reaction time were selected as input parameters to predict the dissolution rate. Experimental dataset was used to train multilayer perceptron (MLP networks to allow for prediction of dissolution kinetics. Developing ANNs has provided highly accurate predictions in comparison with an obtained mathematical model used through regression method. We conclude that ANNs may be a preferred alternative approach instead of conventional statistical methods for prediction of boron minerals.

Magnetic resonance imaging of tablet dissolution.

Science.gov (United States)

Nott, Kevin P

2010-01-01

Magnetic resonance imaging (MRI) is the technique of choice for measuring hydration, and its effects, during dissolution of tablets since it non-invasively maps (1)H nuclei associated with 'mobile' water. Although most studies have used MRI systems with high-field superconducting magnets, low-field laboratory-based instruments based on permanent magnet technology are being developed that provide key data for the formulation scientist. Incorporation of dissolution hardware, in particular the United States Pharmacopeia (USP) apparatus 4 flow-through cell, allows measurements under controlled conditions for comparison against other dissolution methods. Furthermore, simultaneous image acquisition and measurement of drug concentration allow direct comparison of the drug release throughout the hydration process. The combination of low-field MRI with USP-4 apparatus provides another tool to aid tablet formulation. Copyright 2009 Elsevier B.V. All rights reserved.

Effect of dissolution on the load–settlement behavior of shallow foundations

KAUST Repository

Cha, Minsu

2016-03-10

Mineral dissolution and solid-liquid phase change may cause settlement or affect the bearing capacity of shallow foundations. The effect of gradual grain dissolution on small-scale shallow foundation behavior is investigated using the discrete element method. Results show that dissolution is most detrimental during early stages, as initially contacting particles shrink and force chains must reform throughout the medium. Porosity tends to increase during dissolution and force chains evolve into strong localized forces with a honeycomb topology. Higher settlements are required to mobilize bearing resistance in postdissolution sediments than in pre-dissolution ones. Subsurface mineral dissolution beneath a footing under load is the worst condition; in fact, settlements in such cases are higher than when a foundation load is applied on a sediment that has already experienced dissolution. © the author(s) or their institution(s).

Effect of dissolution on the load–settlement behavior of shallow foundations

KAUST Repository

Cha, Minsu; Santamarina, Carlos

2016-01-01

Mineral dissolution and solid-liquid phase change may cause settlement or affect the bearing capacity of shallow foundations. The effect of gradual grain dissolution on small-scale shallow foundation behavior is investigated using the discrete element method. Results show that dissolution is most detrimental during early stages, as initially contacting particles shrink and force chains must reform throughout the medium. Porosity tends to increase during dissolution and force chains evolve into strong localized forces with a honeycomb topology. Higher settlements are required to mobilize bearing resistance in postdissolution sediments than in pre-dissolution ones. Subsurface mineral dissolution beneath a footing under load is the worst condition; in fact, settlements in such cases are higher than when a foundation load is applied on a sediment that has already experienced dissolution. © the author(s) or their institution(s).

Analytical procedure for the in-vial derivatization-extraction of phenolic acids and flavonoids in methanolic and aqueous plant extracts followed by gas chromatography with mass selective detection.

NARCIS (Netherlands)

Fiamegos, Y.C.; Nanos, C.G.; Vervoort, J.J.M.; Stalikas, C.D.

2004-01-01

An in-vial simple method for the combined derivatization and extraction of phenolic acids and flavonoids from plant extracts and their direct determination with GC-MS, is described. The method is taking advantage of the beneficial potentials of phase transfer catalysis (PTC). Catalysts in soluble

Development of a correction factor for Xe-133 vials for use with a dose calibrator

International Nuclear Information System (INIS)

Gels, G.L.; Piltingsrud, H.V.

1982-01-01

Manufacturers of dose calibrators who give calibration settings for various radionuclies sometimes do not specify the type of radionuclide container the calibration is for. The container, moreover, may not be of the same type as those a user might purchase. When these factors are not considered, the activity administered to the patient may be significantly different from that intended. An experiment is described in which calibration factors are determined for measurement of Xe-133 activity in vials in a dose calibrator. This was accomplished by transferring the Xe-133 from the commercial vials to standard NBS calibration ampules. Based on ten such transfers, the resulting correction factor for the dose calibrator was 1.22

Red Vial de Nicaragua (Optimización y Mantenimiento)

OpenAIRE

Wilfredo Martínez

2013-01-01

La red vial es un patrimonio nacional, el cual es necesario: proteger, conservar, aumentar y mejorar; para apoyar eldesarrollo socioeconómico de nuestro país. La actividad de mantenimiento, constituye un factor determinante quegarantiza la operación satisfactoria del transporte durante la vida útil de los caminos; en sus diferentes modalidades. La ausencia de un mantenimiento preventivo y de un mantenimiento correctivo tardío, conduce a que la inversiónrealizada sufra una depreciación más ac...

Dissolution studies on Nickel ferrite in dilute chemical decontamination formulations

Energy Technology Data Exchange (ETDEWEB)

Ranganathan, S. [New Brunswick Univ., Fredericton, NB (Canada). Dept. of Chemical Engineering; Srinivasan, M.P. [Bhabha Atomic Research Centre (BARC) (India). Water and Steam Chemistry Laboratory; Raghavan, P.S. [Madras Christian College, Chennai (India); Narasimhan, S.V. [Bhabha Atomic Research Centre, Bombay (India); Gopalan, R. [Madras Christian College, Chennai (India). Department of Chemistry

2004-09-01

Nickel ferrite is one of the important corrosion products in the pipeline surfaces of water-cooled nuclear reactors. The dissolution of the nickel ferrite by chelating agents is very sensitive to the nature of the chelant, the nature of the reductant used in the formulation and the temperature at which the dissolution studies are performed. The dissolution is mainly controlled by the reductive dissolution of the ferrite particles, but complexing agents also play a significant role in the dissolution process. This study deals with the leaching of iron and nickel from nickel ferrite prepared by the solid-state method. The dissolution studies are performed in pyridine-2,6-dicarboxylic acid (PDCA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA) formulations containing organic reductants like ascorbic acid and low oxidation state transition metal ion reductants like Fe(II)-L (where L = PDCA, NTA, EDTA) at 85 C. The dissolution of nickel ferrite in PDCA, NTA and EDTA formulations is influenced by the presence of reductants in the formulations. The addition of Fe(II)-L in the formulation greatly enhances the dissolution of nickel ferrite. The preferential leaching of nickel over iron during the dissolution of nickel ferrite was observed in all the formulations. (orig.)

Dissolution studies on Nickel ferrite in dilute chemical decontamination formulations

International Nuclear Information System (INIS)

Ranganathan, S.; Narasimhan, S.V.; Gopalan, R.

2004-01-01

Nickel ferrite is one of the important corrosion products in the pipeline surfaces of water-cooled nuclear reactors. The dissolution of the nickel ferrite by chelating agents is very sensitive to the nature of the chelant, the nature of the reductant used in the formulation and the temperature at which the dissolution studies are performed. The dissolution is mainly controlled by the reductive dissolution of the ferrite particles, but complexing agents also play a significant role in the dissolution process. This study deals with the leaching of iron and nickel from nickel ferrite prepared by the solid-state method. The dissolution studies are performed in pyridine-2,6-dicarboxylic acid (PDCA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA) formulations containing organic reductants like ascorbic acid and low oxidation state transition metal ion reductants like Fe(II)-L (where L = PDCA, NTA, EDTA) at 85 C. The dissolution of nickel ferrite in PDCA, NTA and EDTA formulations is influenced by the presence of reductants in the formulations. The addition of Fe(II)-L in the formulation greatly enhances the dissolution of nickel ferrite. The preferential leaching of nickel over iron during the dissolution of nickel ferrite was observed in all the formulations. (orig.)

A kinetic model for borosilicate glass dissolution based on the dissolution affinity of a surface alteration layer

International Nuclear Information System (INIS)

Bourcier, W.L.; Peiffer, D.W.; Knauss, K.G.; McKeegan, K.D.; Smith, D.K.

1989-11-01

A kinetic model for the dissolution of borosilicate glass is used to predict the dissolution rate of a nuclear waste glass. In the model, the glass dissolution rate is controlled by the rate of dissolution of an alkali-depleted amorphous surface (gel) layer. Our model predicts that all components concentrated in the surface layer, affect glass dissolution rates. The good agreement between predicted and observed elemental dissolution rates suggests that the dissolution rate of the gel layer limits the overall rate of glass dissolution. The model predicts that the long-term rate of glass dissolution will depend mainly on ion concentrations in solution, and therefore on the secondary phases which precipitate and control ion concentrations. 10 refs., 5 figs., 1 tab

Equilibrium solubility versus intrinsic dissolution: characterization of lamivudine, stavudine and zidovudine for BCS classification

Directory of Open Access Journals (Sweden)

André Bersani Dezani

2013-12-01

Full Text Available Solubility and dissolution rate of drugs are of major importance in pre-formulation studies of pharmaceutical dosage forms. The solubility improvement allows the drugs to be potential biowaiver candidates and may be a good way to develop more dose-efficient formulations. Solubility behaviour of lamivudine, stavudine and zidovudine in individual solvents (under pH range of 1.2 to 7.5 was studied by equilibrium solubility and intrinsic dissolution methods. In solubility study by equilibrium method (shake-flask technique, known amounts of drug were added in each media until to reach saturation and the mixture was subjected to agitation of 150 rpm for 72 hours at 37 ºC. In intrinsic dissolution test, known amount of each drug was compressed in the matrix of Wood's apparatus and subjected to dissolution in each media with agitation of 50 rpm at 37 ºC. In solubility by equilibrium method, lamivudine and zidovudine can be considered as highly soluble drugs. Although stavudine present high solubility in pH 4.5, 6.8, 7.5 and water, the solubility determination in pH 1.2 was not possible due stability problems. Regarding to intrinsic dissolution, lamivudine and stavudine present high speed of dissolution. Considering a boundary value presented by Yu and colleagues (2004, all drugs studied present high solubility characteristics in intrinsic dissolution method. Based on the obtained results, intrinsic dissolution seems to be superior for solubility studies as an alternative method for biopharmaceutical classification purposes.

LA IMPORTANCIA DE LOS EJES DE FIJACIÓN DEL PAISAJE URBANO EN LA EDUCACIÓN VIAL

OpenAIRE

Nina, Mónica Marianela; Filippeti, Rosana; Pauletto, Selva del Valle

2012-01-01

La enseñanza de los ejes de fijación en el espacio urbano son elementos que deben ser vinculados con la educación vial ya que la misma no forma parte del diseño curricular en la educación formal. El propósito del presente trabajo es que a través de la enseñanza de las funciones de las arterias de circulación como calles, avenidas, rutas, autopistas se busca la toma de conciencia de los jóvenes de la importancia de conocer los principios de la educación vial para prevenir los accidentes de trá...

Predicting the dissolution kinetics of silicate glasses using machine learning

Science.gov (United States)

Anoop Krishnan, N. M.; Mangalathu, Sujith; Smedskjaer, Morten M.; Tandia, Adama; Burton, Henry; Bauchy, Mathieu

2018-05-01

Predicting the dissolution rates of silicate glasses in aqueous conditions is a complex task as the underlying mechanism(s) remain poorly understood and the dissolution kinetics can depend on a large number of intrinsic and extrinsic factors. Here, we assess the potential of data-driven models based on machine learning to predict the dissolution rates of various aluminosilicate glasses exposed to a wide range of solution pH values, from acidic to caustic conditions. Four classes of machine learning methods are investigated, namely, linear regression, support vector machine regression, random forest, and artificial neural network. We observe that, although linear methods all fail to describe the dissolution kinetics, the artificial neural network approach offers excellent predictions, thanks to its inherent ability to handle non-linear data. Overall, we suggest that a more extensive use of machine learning approaches could significantly accelerate the design of novel glasses with tailored properties.

Dissolution study of thorium-uranium oxides in aqueous triflic acid solutions

Energy Technology Data Exchange (ETDEWEB)

Bulemela, E.; Bergeron, A.; Stoddard, T. [Canadian Nuclear Laboratories - CNL, 286 Plant Rd., Chalk River, Ontario, K0J 1J0 (Canada)

2016-07-01

The dissolution of sintered mixed oxides of thorium with uranium in various concentrations of trifluoromethanesulfonic (triflic) acid solutions was investigated under reflux conditions to evaluate the suitability of the method. Various fragment sizes (1.00 mm < x < 7.30 mm) of sintered (Th,U)O{sub 2} and simulated high-burnup nuclear fuel (SIMFUEL) were almost completely dissolved in a few hours, which implies that triflic acid could be used as an alternative to the common dissolution method, involving nitric acid-hydrofluoric acid mixture. The influence of acid concentration, composition of the solids, and reaction time on the dissolution yield of Th and U ions was studied using Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). The dissolution rate was found to depend upon the triflic acid concentration and size of the solid fragments, with near complete dissolution for the smallest fragments occurring in boiling 87% w/w triflic acid. The formation of Th and U ions in solution appears to occur at the same rate as the triflic acid simultaneously reacts with the constituent oxides as evidenced by the results of a constant U/Th concentration ratio with the progress of the dissolution. (authors)

Feldspar dissolution rates in the Topopah Spring Tuff, Yucca Mountain, Nevada

Science.gov (United States)

Bryan, C.R.; Helean, K.B.; Marshall, B.D.; Brady, P.V.

2009-01-01

Two different field-based methods are used here to calculate feldspar dissolution rates in the Topopah Spring Tuff, the host rock for the proposed nuclear waste repository at Yucca Mountain, Nevada. The center of the tuff is a high silica rhyolite, consisting largely of alkali feldspar (???60 wt%) and quartz polymorphs (???35 wt%) that formed by devitrification of rhyolitic glass as the tuff cooled. First, the abundance of secondary aluminosilicates is used to estimate the cumulative amount of feldspar dissolution over the history of the tuff, and an ambient dissolution rate is calculated by using the estimated thermal history. Second, the feldspar dissolution rate is calculated by using measured Sr isotope compositions for the pore water and rock. Pore waters display systematic changes in Sr isotopic composition with depth that are caused by feldspar dissolution. The range in dissolution rates determined from secondary mineral abundances varies from 10-16 to 10-17 mol s-1 kg tuff-1 with the largest uncertainty being the effect of the early thermal history of the tuff. Dissolution rates based on pore water Sr isotopic data were calculated by treating percolation flux parametrically, and vary from 10-15 to 10-16 mol s-1 kg tuff-1 for percolation fluxes of 15 mm a-1 and 1 mm a-1, respectively. Reconciling the rates from the two methods requires that percolation fluxes at the sampled locations be a few mm a-1 or less. The calculated feldspar dissolution rates are low relative to other measured field-based feldspar dissolution rates, possibly due to the age (12.8 Ma) of the unsaturated system at Yucca Mountain; because oxidizing and organic-poor conditions limit biological activity; and/or because elevated silica concentrations in the pore waters (???50 mg L-1) may inhibit feldspar dissolution. ?? 2009 Elsevier Ltd. All rights reserved.

Thoria/thoria-urania dissolution studies for reprocessing application

International Nuclear Information System (INIS)

Srinivas, C.; Yalmali, Vrunda; Pente, A.S.; Wattal, P.K.; Misra, S.D.

2012-06-01

Thoria dissolution is normally conducted in 13M nitric acid in the presence of 0.03M sodium fluoride or HF as catalyst and 0.1M aluminium nitrate for mitigation of fluoride related corrosion of SS 304L dissolver vessel. Addition of aluminium nitrate in such high concentrations has undesirable consequences in the downstream high level radioactive liquid waste vitrification process at 900-1000 degC. Besides, because of the highly corrosive nature of fluoride ion, lowering its concentration in the dissolution reaction is advantageous in reducing the corrosion of dissolver and other downstream equipments. The present work was done with twin objectives of avoiding aluminium nitrate addition and lowering the fluoride ion concentration during dissolution reaction. High temperature sintered thoria and thoria-4 weight% urania dissolution reactions were investigated in the absence of aluminium nitrate and at reduced fluoride concentrations. Corrosion rates of SS 304L zircaloy in various dissolvent mixtures were studied by weight loss method. These studies clearly showed that aluminium nitrate addition for control of fluoride related corrosion of SS 304L can be avoided when zircaloy-clad thoria/thoria-urania pellets are dissolved. Dissolved zirconium ion was observed to be as effective as aluminium ion. Moreover, dissolution could be achieved with reasonable reaction rates at reduced fluoride concentration of 0.005-0.01M instead of 0.03M by changing the method of addition of the fluoride catalyst. (author)

Preparation of one-vial reduced anti-CEA kit

International Nuclear Information System (INIS)

Hamada, Elena Setuko; Muramoto, Emiko; Shiraishi, Emilia Mayumi; Silva, Licia Maria Britto da; Martins, Heidi Pinto; Silva, Constanca Pagano Goncalves da

1996-01-01

A rapid and reliable instant reduced anti-CEA lyophilized kit for labelling with 99m Tc was developed. Each vial contains 0.5 mg of reduced anti-CEA, 40 μg of mendronate (MDP), 2.75 μg stannous fluoride (Sn F 2 ) and 15 μ g p-aminobenzoic acid (PABA). Labeling efficiency and stability were higher than 95% and were determined by instant paper chromatography. Biodistribution studies were performed in normal isogenic BALB/c mice at 4,6 and 24 hours after intravenous administration of the radiolabelled product. The maximum amount of activity was accumulated in the liver followed by intestines and kidneys. (author)

Development and validation of dissolution study of sustained release dextromethorphan hydrobromide tablets.

Science.gov (United States)

Rajan, Sekar; Colaco, Socorrina; Ramesh, N; Meyyanathan, Subramania Nainar; Elango, K

2014-02-01

This study describes the development and validation of dissolution tests for sustained release Dextromethorphan hydrobromide tablets using an HPLC method. Chromatographic separation was achieved on a C18 column utilizing 0.5% triethylamine (pH 7.5) and acetonitrile in the ratio of 50:50. The detection wavelength was 280 nm. The method was validated and response was found to be linear in the drug concentration range of 10-80 microg mL(-1). The suitable conditions were clearly decided after testing sink conditions, dissolution medium and agitation intensity. The most excellent dissolution conditions tested, for the Dextromethorphan hydrobromide was applied to appraise the dissolution profiles. The method was validated and response was found to be linear in the drug concentration range of 10-80 microg mL(-1). The method was established to have sufficient intermediate precision as similar separation was achieved on another instrument handled by different operators. Mean Recovery was 101.82%. Intra precisions for three different concentrations were 1.23, 1.10 0.72 and 1.57, 1.69, 0.95 and inter run precisions were % RSD 0.83, 1.36 and 1.57%, respectively. The method was successfully applied for dissolution study of the developed Dextromethorphan hydrobromide tablets.

Standard practice for preparation and dissolution of plutonium materials for analysis

CERN Document Server

American Society for Testing and Materials. Philadelphia

2008-01-01

1.1 This practice is a compilation of dissolution techniques for plutonium materials that are applicable to the test methods used for characterizing these materials. Dissolution treatments for the major plutonium materials assayed for plutonium or analyzed for other components are listed. Aliquants of the dissolved samples are dispensed on a weight basis when one of the analyses must be highly reliable, such as plutonium assay; otherwise they are dispensed on a volume basis. 1.2 The treatments, in order of presentation, are as follows: Procedure Title Section Dissolution of Plutonium Metal with Hydrochloric Acid 9.1 Dissolution of Plutonium Metal with Sulfuric Acid 9.2 Dissolution of Plutonium Oxide and Uranium-Plutonium Mixed Oxide by the Sealed-Reflux Technique 9.3 Dissolution of Plutonium Oxide and Uranium-Plutonium Mixed Oxides by Sodium Bisulfate Fusion 9.4 Dissolution of Uranium-Plutonium Mixed Oxides and Low-Fired Plutonium Oxide in Beakers 9.5 1.3 The values stated in SI units are to be re...

Solubility and dissolution improvement of ketoprofen by emulsification ionic gelation

Science.gov (United States)

Rachmaniar, Revika; Tristiyanti, Deby; Hamdani, Syarif; Afifah

2018-02-01

Ketoprofen or [2-(3-benzoylphenyl) propionic acid] is non-steroidal anti-inflammatory (NSAID) and an analgesic which has high permeability and low solubility. The purpose of this work was to improve the solubility and dissolution of poorly water-soluble ketoprofen prepared by emulsification ionic gelation method and utilizing polymer (chitosan) and cross linker (tripolyphosphate, TPP) for particles formulation. The results show that increasing pH value of TPP, higher solubility and dissolution of as-prepared ketoprofen-chitosan was obtained. The solubility in water of ketoprofen-chitosan with pH 6 for TPP increased 2.71-fold compared to untreated ketoprofen. While the dissolution of ketoprofen-chitosan with pH 6 of TPP in simulated gastric fluid without enzyme (0.1 N HCl), pH 4.5 buffer and simulated intestinal fluid without enzyme (phosphate buffer pH 6.8) was increased 1.9-fold, 1.6-fold and 1.2-fold compared to untreated ketoprofen for dissolution time of 30 minutes, respectively. It could be concluded that chitosan and TPP in the emulsification ionic gelation method for ketoprofen preparation effectively increases solubility and dissolution of poorly water-soluble ketoprofen.

Correlation of dissolution and disintegration results for an immediate-release tablet.

Science.gov (United States)

Nickerson, Beverly; Kong, Angela; Gerst, Paul; Kao, Shangming

2018-02-20

The drug release rate of a rapidly dissolving immediate-release tablet formulation with a highly soluble drug is proposed to be controlled by the disintegration rate of the tablet. Disintegration and dissolution test methods used to evaluate the tablets were shown to discriminate manufacturing process differences and compositionally variant tablets. In addition, a correlation was established between disintegration and dissolution. In accordance with ICH Q6A, this work demonstrates that disintegration in lieu of dissolution is suitable as the drug product quality control method for evaluating this drug product. Copyright © 2017 Elsevier B.V. All rights reserved.

Hydro-chemo-mechanical coupling in sediments: Localized mineral dissolution

KAUST Repository

Cha, Minsu; Santamarina, Carlos

2016-01-01

Mineral dissolution is inherently a chemo-hydro-mechanical coupled process. Field evidence and laboratory results show that dissolution may localize and form open conduits in cohesive media such as carbonate rocks. This study focuses on the evolution of localized dissolution in soils (i.e., frictional and non-cohesive granular materials) under effective confining stresses. Experimental results show the development of localized dissolution (“pipe”) when a carbonate-quartz sand is subjected to reactive fluid flow: only loosely packed quartz grains remain within pipes, and the number of pipes decreases away from the inlet port. Concurrent shear wave velocity measurements show a decrease in stiffness during dissolution due to stress and fabric changes, and more complex signal codas anticipate the development of internal heterogeneity. The discrete element method is used to simulate localized vertical dissolution features in granular materials, under constant vertical stress and zero lateral strain far-field boundaries. As porosity increases along dissolution pipes, vertical load is transferred to the surrounding soils and marked force chains develop. In terms of equivalent stress, principal stress rotation takes place within pipes and the sediment reaches the Coulomb failure condition inside pipes and in the surrounding medium. Dissolution pipes alter the geo-plumbing of the subsurface, enhance fluid transport but limit the long term performance of storage systems, alter the fluid pressure and effective stress fields, soften the sediment and may trigger shear failures.

Hydro-chemo-mechanical coupling in sediments: Localized mineral dissolution

KAUST Repository

Cha, Minsu

2016-06-11

Mineral dissolution is inherently a chemo-hydro-mechanical coupled process. Field evidence and laboratory results show that dissolution may localize and form open conduits in cohesive media such as carbonate rocks. This study focuses on the evolution of localized dissolution in soils (i.e., frictional and non-cohesive granular materials) under effective confining stresses. Experimental results show the development of localized dissolution (“pipe”) when a carbonate-quartz sand is subjected to reactive fluid flow: only loosely packed quartz grains remain within pipes, and the number of pipes decreases away from the inlet port. Concurrent shear wave velocity measurements show a decrease in stiffness during dissolution due to stress and fabric changes, and more complex signal codas anticipate the development of internal heterogeneity. The discrete element method is used to simulate localized vertical dissolution features in granular materials, under constant vertical stress and zero lateral strain far-field boundaries. As porosity increases along dissolution pipes, vertical load is transferred to the surrounding soils and marked force chains develop. In terms of equivalent stress, principal stress rotation takes place within pipes and the sediment reaches the Coulomb failure condition inside pipes and in the surrounding medium. Dissolution pipes alter the geo-plumbing of the subsurface, enhance fluid transport but limit the long term performance of storage systems, alter the fluid pressure and effective stress fields, soften the sediment and may trigger shear failures.

Evaluation of a three compartment in vitro gastrointestinal simulator dissolution apparatus to predict in vivo dissolution.

Science.gov (United States)

Takeuchi, Susumu; Tsume, Yasuhiro; Amidon, Gregory E; Amidon, Gordon L

2014-11-01

In vitro dissolution tests are performed for new formulations to evaluate in vivo performance, which is affected by the change of gastrointestinal (GI) physiology, in the GI tract. Thus, those environmental changes should be introduced to an in vitro dissolution test. Many studies have successfully shown the improvement of in vitro-in vivo correlations (IVIVC) by introducing those physiological changes into dissolution tests. The gastrointestinal simulator (GIS), a multicompartment in vitro dissolution apparatus, was developed to evaluate in vivo drug dissolution. A gastric-emptying rate along with transit rate are key factors to evaluate in vivo drug dissolution and, hence, drug absorption. Dissolution tests with the GIS were performed with Biopharmaceutical Classification System class I drugs at five different gastric-emptying rates in the fasted state. Computational models were used to determine in vivo gastric-emptying time for propranolol and metoprolol based on the GIS dissolution results. Those were compared with published clinical data to determine the gastric half-emptying time. In conclusion, the GIS is a practical tool to assess dissolution properties and can improve IVIVC. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

Plutonium oxide dissolution

International Nuclear Information System (INIS)

Gray, J.H.

1992-01-01

Several processing options for dissolving plutonium oxide (PuO 2 ) from high-fired materials have been studied. The scoping studies performed on these options were focused on PuO 2 typically generated by burning plutonium metal and PuO 2 produced during incineration of alpha contaminated waste. At least two processing options remain applicable for dissolving high-fired PuO 2 in canyon dissolvers. The options involve solid solution formation of PuO 2 With uranium oxide (UO 2 ) and alloying incinerator ash with aluminum. An oxidative dissolution process involving nitric acid solutions containing a strong oxidizing agent, such as cerium (IV), was neither proven nor rejected. This uncertainty was due to difficulty in regenerating cerium (IV) ions during dissolution. However, recent work on silver-catalyzed dissolution of PuO 2 with persulfate has demonstrated that persulfate ions regenerate silver (II). Use of persulfate to regenerate cerium (IV) or bismuth (V) ions during dissolution of PuO 2 materials may warrant further study

Measurement of soluble nuclide dissolution rates from spent fuel

International Nuclear Information System (INIS)

Wilson, C.N.; Gray, W.J.

1990-01-01

Gaining a better understanding of the potential release behavior of water-soluble radionuclides is the focus of new laboratory spent fuel dissolution studies being planned in support of the Yucca Mountain Project. Previous studies have suggested that maximum release rates for actinide nuclides, which account for most of the long-term radioactivity in spent fuel, should be solubility-limited and should not depend on the characteristics or durability of the spent fuel waste form. Maximum actinide concentrations should be sufficiently low to meet the NRC (Nuclear Regulatory Commission) annual release limits. Potential release rates for soluble nuclides such as 99 Tc, 135 Cs, 14 C and 129 I, which account for about 1-2% of the activity in spent fuel at 1,000 years, are less certain and may depend on processes such as oxidation of the fuel in the repository air environment. Dissolution rates for several soluble nuclides have been measured from spent fuel specimens using static and semi-static methods. However, such tests do not provide a direct measurement of fuel matrix dissolution rates that may ultimately control soluble-nuclide release rates. Flow-through tests are being developed as a potential supplemental method for determining the matrix component of soluble-nuclide dissolution. Advantages and disadvantages of both semi-static and flow-through methods are discussed. Tests with fuel specimens representing a range of potential fuel states that may occur in the repository, including oxidized fuel, are proposed. Preliminary results from flow-through tests with unirradiated UO 2 suggesting that matrix dissolution rates are very sensitive to water composition are also presented

Plutonium dissolution from Rocky Flats Plant incinerator ash

International Nuclear Information System (INIS)

Delegard, C.H.

1985-06-01

Rockwell Hanford Operations (Rockwell) soon will commence recovery of plutonium from Rocky Flats Plant incinerator ash. In preparation for this processing, Rockwell undertook literature and laboratory studies to identify, select and optimize plutonium dissolution methods for treating the ash. Ash reburning, followed by dissolution in nitric acid containing calcium fluoride, was selected as the processing method for the ash. Recommended values of process parameters were identified. Using the selected process, 99.5% plutonium recovery was achieved, leaving about 12.7 wt % heel residue for an equal weight composite of the three ashes tested. 15 refs., 26 figs

A method for phenomenological and chemical kinetics study of autocatalytic reactive dissolution by optical microscopy. The case of uranium dioxide dissolution in nitric acid media

Science.gov (United States)

Marc, Philippe; Magnaldo, Alastair; Godard, Jérémy; Schaer, Éric

2018-03-01

Dissolution is a milestone of the head-end of hydrometallurgical processes, as the stabilization rates of the chemical elements determine the process performance and hold-up. This study aims at better understanding the chemical and physico-chemical phenomena of uranium dioxide dissolution reactions in nitric acid media in the Purex process, which separates the reusable materials and the final wastes of the spent nuclear fuels. It has been documented that the attack of sintering-manufactured uranium dioxide solids occurs through preferential attack sites, which leads to the development of cracks in the solids. Optical microscopy observations show that in some cases, the development of these cracks leads to the solid cleavage. It is shown here that the dissolution of the detached fragments is much slower than the process of the complete cleavage of the solid, and occurs with no disturbing phenomena, like gas bubbling. This fact has motivated the measurement of dissolution kinetics using optical microscopy and image processing. By further discriminating between external resistance and chemical reaction, the "true" chemical kinetics of the reaction have been measured, and the highly autocatalytic nature of the reaction confirmed. Based on these results, the constants of the chemical reactions kinetic laws have also been evaluated.

A method for phenomenological and chemical kinetics study of autocatalytic reactive dissolution by optical microscopy. The case of uranium dioxide dissolution in nitric acid media

Directory of Open Access Journals (Sweden)

Marc Philippe

2018-01-01

Full Text Available Dissolution is a milestone of the head-end of hydrometallurgical processes, as the stabilization rates of the chemical elements determine the process performance and hold-up. This study aims at better understanding the chemical and physico-chemical phenomena of uranium dioxide dissolution reactions in nitric acid media in the Purex process, which separates the reusable materials and the final wastes of the spent nuclear fuels. It has been documented that the attack of sintering-manufactured uranium dioxide solids occurs through preferential attack sites, which leads to the development of cracks in the solids. Optical microscopy observations show that in some cases, the development of these cracks leads to the solid cleavage. It is shown here that the dissolution of the detached fragments is much slower than the process of the complete cleavage of the solid, and occurs with no disturbing phenomena, like gas bubbling. This fact has motivated the measurement of dissolution kinetics using optical microscopy and image processing. By further discriminating between external resistance and chemical reaction, the “true” chemical kinetics of the reaction have been measured, and the highly autocatalytic nature of the reaction confirmed. Based on these results, the constants of the chemical reactions kinetic laws have also been evaluated.

Dissolution of aluminium; Disolucion de aluminio

Energy Technology Data Exchange (ETDEWEB)

Uriarte Hueda, A; Berberana Eizmendi, M; Pereira Sanchez, G

1968-07-01

The dissolution of aluminum with acid solutions ( nitric acid-mercuric nitrate) and alkaline solutions (sodium hydroxide-sodium nitrate) has been studied. The instantaneous dissolution rate (IDR) has been studied in function of the concentration of the used reagents and the dissolution temperature. The complete dissolution has been included in the second part of this report, to know the total dissolution time, the consume of reagents and the stability of the resultant solutions. (Author)

Selección de alternativas de inversión en la construcción de obras viales en la ciudad de México

OpenAIRE

Palomas-Molina, X.; Álvarez-Icaza, L.

2010-01-01

Se propone un método sistemático con el que se analiza un conjunto de nodos viales de la ciudad de México con altos índices de ocupación para decidir sobre la posible realización de algunos tipos de obras viales en los mismos. El método permite obtener, a través del análisis estadístico de información y de la programación entera, las mejores opciones para invertir en la construcción de estas obras viales bajo un escenario de recursos limitados. La decisión se toma por un lado, con base en los...

Aluminum Target Dissolution in Support of the Pu-238 Program

Energy Technology Data Exchange (ETDEWEB)

McFarlane, Joanna [ORNL; Benker, Dennis [ORNL; DePaoli, David W [ORNL; Felker, Leslie Kevin [ORNL; Mattus, Catherine H [ORNL

2014-09-01

Selection of an aluminum alloy for target cladding affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the caustic dissolution step, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. We present a study to maximize dissolution of aluminum metal alloy, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as a function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. These data have been compared with published calculations of aluminum phase diagrams. Temperature logging during the transients has been investigated as a means to generate kinetic and mass transport data on the dissolution process. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.

Metabolomic method: UPLC-q-ToF polar and non-polar metabolites in the healthy rat cerebellum using an in-vial dual extraction.

Directory of Open Access Journals (Sweden)

Amera A Ebshiana

Full Text Available Unbiased metabolomic analysis of biological samples is a powerful and increasingly commonly utilised tool, especially for the analysis of bio-fluids to identify candidate biomarkers. To date however only a small number of metabolomic studies have been applied to studying the metabolite composition of tissue samples, this is due, in part to a number of technical challenges including scarcity of material and difficulty in extracting metabolites. The aim of this study was to develop a method for maximising the biological information obtained from small tissue samples by optimising sample preparation, LC-MS analysis and metabolite identification. Here we describe an in-vial dual extraction (IVDE method, with reversed phase and hydrophilic liquid interaction chromatography (HILIC which reproducibly measured over 4,000 metabolite features from as little as 3mg of brain tissue. The aqueous phase was analysed in positive and negative modes following HILIC separation in which 2,838 metabolite features were consistently measured including amino acids, sugars and purine bases. The non-aqueous phase was also analysed in positive and negative modes following reversed phase separation gradients respectively from which 1,183 metabolite features were consistently measured representing metabolites such as phosphatidylcholines, sphingolipids and triacylglycerides. The described metabolomics method includes a database for 200 metabolites, retention time, mass and relative intensity, and presents the basal metabolite composition for brain tissue in the healthy rat cerebellum.

Solid dispersion of dutasteride using the solvent evaporation method: Approaches to improve dissolution rate and oral bioavailability in rats.

Science.gov (United States)

Choi, Jin-Seok; Lee, Sang-Eun; Jang, Woo Suk; Byeon, Jong Chan; Park, Jeong-Sook

2018-09-01

The aim of this study was to develop a dutasteride (DUT) solid dispersion (SD) using hydrophilic substances to enhance its dissolution (%) and oral bioavailability in rats. DUT-SD formulations were prepared with various co-polymers using a solvent evaporation method. The physical properties of DUT-SD formulations were confirmed using field emission scanning electron microscopy (FE-SEM), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and attenuated total reflectance Fourier transform infrared (ATR-FT-IR) spectroscopy. The toxicity and oral bioavailability of DUT-SD formulations were evaluated. Tocopheryl polyethylene glycol-1000-succinate (TPGS) was chosen as the solubilizer; and methylene chloride, and Aerosil® 200 or microcrystalline cellulose (MCC) were chosen as the solvent and carrier, respectively, based on a solubility test and pre-dissolution study. The dissolution levels of DUT-SD formulations were 86.3 ± 2.3% (F15) and 95.1 ± 1.9% (F16) after 1 h, which were higher than those of the commercial product, i.e., Avodart® (75.8 ± 1.5%) in 0.1 N HCl containing 1% (w/v) sodium lauryl sulfate (SLS). The F16 formulation was found to be stable, after assessing its dissolution (%) and drug content (%) for 6 months. The DUT-SD formulations resulted in relative bioavailability (BA) values of 126.4% (F15) and 132.1% (F16), which were enhanced compared to that of Avodart®. Dissolution (%) and relative BA values were both increased by hydrogen interaction between TPGS and DUT. This study might contribute to a new formulation (powder) whose oral bioavailability is greater than that of Avodart® (soft capsule), which could facilitate to the use of the SD system during the production process. Copyright © 2018 Elsevier B.V. All rights reserved.

Solid–liquid phase equilibrium and dissolution properties of ethyl vanillin in pure solvents

International Nuclear Information System (INIS)

Wu, Hao; Wang, Jingkang; Zhou, Yanan; Guo, Nannan; Liu, Qi; Zong, Shuyi; Bao, Ying; Hao, Hongxun

2017-01-01

Highlights: • Solubility of ethyl vanillin in eight pure solvents were determined by a static analytical method. • The experimental solubility data of ethyl vanillin were correlated and analyzed by four thermodynamic models. • Dissolution thermodynamic properties of ethyl vanillin were calculated and discussed. - Abstract: The solubility of ethyl vanillin (EVA) in eight pure solvents were determined in different temperature ranges from (273.15 to 318.15) K by a static analytical method. In the temperature ranges investigated, it was found that the solubility of EVA in all the selected solvents increased with the rising of temperature. Furthermore, four thermodynamic models were used to correlate the experimental solubility data and the calculation results showed that selected models can be used to correlate the solubility data with satisfactory accuracy. Finally, the dissolution thermodynamic properties, including dissolution Gibbs energy, dissolution enthalpy and dissolution entropy of EVA in the eight selected solvents were calculated.

Mathematical modeling of drug dissolution.

Science.gov (United States)

Siepmann, J; Siepmann, F

2013-08-30

The dissolution of a drug administered in the solid state is a pre-requisite for efficient subsequent transport within the human body. This is because only dissolved drug molecules/ions/atoms are able to diffuse, e.g. through living tissue. Thus, generally major barriers, including the mucosa of the gastro intestinal tract, can only be crossed after dissolution. Consequently, the process of dissolution is of fundamental importance for the bioavailability and, hence, therapeutic efficacy of various pharmaco-treatments. Poor aqueous solubility and/or very low dissolution rates potentially lead to insufficient availability at the site of action and, hence, failure of the treatment in vivo, despite a potentially ideal chemical structure of the drug to interact with its target site. Different physical phenomena are involved in the process of drug dissolution in an aqueous body fluid, namely the wetting of the particle's surface, breakdown of solid state bonds, solvation, diffusion through the liquid unstirred boundary layer surrounding the particle as well as convection in the surrounding bulk fluid. Appropriate mathematical equations can be used to quantify these mass transport steps, and more or less complex theories can be developed to describe the resulting drug dissolution kinetics. This article gives an overview on the current state of the art of modeling drug dissolution and points out the assumptions the different theories are based on. Various practical examples are given in order to illustrate the benefits of such models. This review is not restricted to mathematical theories considering drugs exhibiting poor aqueous solubility and/or low dissolution rates, but also addresses models quantifying drug release from controlled release dosage forms, in which the process of drug dissolution plays a major role. Copyright © 2013 Elsevier B.V. All rights reserved.

Solvent removal and spore inactivation directly in dispensing vials with supercritical carbon dioxide and sterilant.

Science.gov (United States)

Howell, Jahna; Niu, Fengui; McCabe, Shannon E; Zhou, Wei; Decedue, Charles J

2012-06-01

A process is described using supercritical carbon dioxide to extract organic solvents from drug solutions contained in 30-mL serum vials. We report drying times of less than 1 h with quantitative recovery of sterile drug. A six-log reduction of three spore types used as biological indicators is achieved with direct addition of peracetic acid to a final concentration of approximately 5 mM (~0.04 %) to the drug solution in the vial. Analysis of two drugs, acetaminophen and paclitaxel, indicated no drug degradation as a result of the treatment. Furthermore, analysis of the processed drug substance showed that no residual peracetic acid could be detected in the final product. We have demonstrated an effective means to simultaneously dry and sterilize active pharmaceutical ingredients from organic solvents directly in a dispensing container.

La Webquest como innovación educativa en el ámbito de la educación vial

Directory of Open Access Journals (Sweden)

Rosa María GOIG MARTÍNEZ

2013-01-01

Full Text Available La Educación Vial en las edades tempranas se puede implementar a través de cuentos, talleres, rincones de juego, patios de recreo, salidas extraescolares, actividades de psicomotricidad. Sin embargo, es importante destacar el papel de las Tecnologías de la Información y la Comunicación en el enriquecimiento de las propuestas de aula en relación a la Educación Vial, tomándolas como recurso complementario, en nuestro contexto, la Webquest. Sin olvidar la necesidad de seguir trabajando con los niños y las niñas situaciones reales ligadas a sus experiencias vitales en materia de Educación Vial, pues el mundo real nunca debiera ser desplazado por el mundo virtual en ningún caso, máxime si tenemos en cuenta que se trata de la etapa de Educación Infantil. El objetivo general de este artículo es corroborar que la Webquest constituye una auténtica oportunidad para innovar en el ámbito de la Educación Vial, ofreciendo al alumnado experiencias didácticas coherentes y complementarias desde la etapa de Educación Infantil. La metodología, de carácter cuantitativo y cualitativo, se desarrolló a través de la aplicación de un cuestionario, de una entrevista, del análisis documental y su triangulación, finalizando con el análisis de los datos obtenidos. Una de las conclusiones obtenidas expone que la Webquest es un recurso que nos facilita el proceso de enseñanza-aprendizaje y aumenta la motivación tanto en alumnos como en agentes educativos.

Influence of the Efavirenz Micronization on Tableting and Dissolution

Directory of Open Access Journals (Sweden)

Lucio Mendes Cabral

2012-09-01

Full Text Available The purpose of this study was to propose an analytical procedure that provides the effects of particle size and surface area on dissolution of efavirenz. Five different batches obtained by different micronization processes and with different particle size distribution and surface area were studied. The preformulation studies and dissolution curves were used to confirm the particle size distribution effect on drug solubility. No polymorphic variety or amorphization was observed in the tested batches and the particle size distribution was determined as directly responsible for the improvement of drug dissolution. The influence of the preparation process on the tablets derived from efavirenz was observed in the final dissolution result in which agglomeration, usually seen in non-lipophilic micronized material, was avoided through the use of an appropriate wet granulation method. For these reasons, micronization may represent one viable alternative for the formulation of brick dust drugs.

Studies on PEM fuel cell noble metal catalyst dissolution

DEFF Research Database (Denmark)

Andersen, S. M.; Grahl-Madsen, L.; Skou, E. M.

2011-01-01

A combination of electrochemical, spectroscopic and gravimetric methods was carried out on Proton Exchange Membrane (PEM) fuel cell electrodes with the focus on platinum and ruthenium catalysts dissolution, and the membrane degradation. In cyclic voltammetry (CV) experiments, the noble metals were...... found to dissolve in 1 M sulfuric acid solution and the dissolution increased exponentially with the upper potential limit (UPL) between 0.6 and 1.6 vs. RHE. 2-20% of the Pt (depending on the catalyst type) was found to be dissolved during the experiments. Under the same conditions, 30-100% of the Ru...... (depending on the catalyst type) was found to be dissolved. The faster dissolution of ruthenium compared to platinum in the alloy type catalysts was also confirmed by X-ray diffraction measurements. The dissolution of the carbon supported catalyst was found one order of magnitude higher than the unsupported...

Dissolution of two NWCF calcines: Extent of dissolution and characterization of undissolved solids

International Nuclear Information System (INIS)

Brewer, K.N.; Herbst, R.S.; Tranter, T.J.

1995-01-01

A study was undertaken to determine the dissolution characteristics of two NWCF calcine types. A two-way blended calcine made from 4 parts nonradioactive aluminum nitrate and one part WM-102 was studied to determine the extent of dissolution for aluminum-type calcines. A two-way blend of 3.5 parts fluorinel waste from WM-187 and 1 part sodium waste from WM-185 was used to determine the extent of dissolution for zirconium-type calcines. This study was necessary to develop suitable aqueous separation flowsheets for the partitioning of actinides and fission products from ICPP calcines and to determine the disposition of the resulting undissolved solids (UDS). The dissolution flowsheet developed by Herbst was used to dissolve these two NWCF calcine types. Results show that greater than 95 wt% of aluminum and zirconium calcine types were dissolved after a single batch contact with 5 M HNO 3 . A characterization of the UDS indicates that the weight percent of TRU elements in the UDS resulting from both calcine type dissolutions increases by approximately an order of magnitude from their concentrations prior to dissolution. Substantial activities of cesium and strontium are also present in the UDS resulting from the dissolution of both calcine types. Multiple TRU, Cs, and Sr analyses of both UDS types show that these solids are relatively homogeneous. From this study, it is estimated that between 63.5 and 635 cubic meters of UDS will be generated from the dissolution of 3800 M 3 of calcine. The significant actinide and fission product activities in these UDS will preclude their disposal as low-level waste. If the actinide and fission activity resulting from the UDS is the only considered source in the dissolved calcine solutions, an estimated 99.9 to 99.99 percent of the solids must be removed from this solution for it to meet non-TRU Class A low-level waste

Dissolution Behavior and Content Uniformity of An Improved Tablet Formulation Assayed by Spectrofluorometric and RIA Methods

Directory of Open Access Journals (Sweden)

Morteza Rafiee-Tehrani

1990-06-01

Full Text Available Digoxin 0.25 mg tablets were manufactured by pregranulation of lactose-fcorn starch with 10% corn starch paste and deposition of solvent on pregranules to make digoxin granules. In the preparation of tablet A, granules of lactose-corn Starch was uniformly moistened with a 5% chloroform-ethanol solution (2:lv/vof digoxin by a simple blending. Tablet B was produced by spray granulation system on which the solvent was sprayed on the granules of lactose-corn starch by utilization of a laboratory size fluidized bed drier (Uniglatt . The content uniformity and dissolution of both tablets were determined by the spectrofluorometric and radio¬immunoassay (RIA method modified for the assay of tablet solutious. One available commercially brand of digoxin tablet (C was included in dissolution study for comparison. For the spectrofluorometric method the technique is based on the fluor-ometric measurenent of the dehydration product of the cardiotonic steroid resulting from its reaction with hydrogen peroxide in concentrated hydrochloric acid. For the RIA method, the filtrate was diluted to theoretical concentration of 2.5 ng/ml."nAliquots of this dilution were then assayed for digoxin content using a commercial digoxin125 I RIA kit. Results from both assay methods were extrapolated to the total tablet content and compared with the labeled amount of 20 individual tablets. All tablet assay results were within the USP standards for the content uniformity and"ndissolution of individual. The individual tablet deviations from labeled amount by RIA method were smaller when compared with the spectrofluorometric method.There was no significant difference between the release of digoxin from three products, and thus it is suggested that the Procedure B could be easily applied for manufacturing"nof digoxin tablets in industrial scales.It was also concluded that,the RIA method could be used for the digoxin tablet determination.

UO2 dissolution rates: A review

International Nuclear Information System (INIS)

McKenzie, W.F.

1992-09-01

This report reviews literature data on UO 2 dissolution kinetics and provides a framework for guiding future experimental studies as well as theoretical modeling studies. Under oxidizing conditions, UO 2 dissolution involves formation of an oxidized surface layer which is then dissolved by formation of aqueous complexes. Higher oxygen pressures or other oxidants are required at higher temperatures to have dissolution rates independent of oxygen pressure. At high oxygen pressures (1-5 atm, 25-70 C), the dissolution rate has a one-half order dependence on oxygen pressure, whereas at oxygen pressures below 0.2 atm, Grandstaff (1976), but nobody else, observed a first-order dependence on dissolution rate. Most people found a first-order dependence on carbonate concentration; Posey-Dowty (1987) found independence of carbonate at pH 7 to 8.2. Dissolution rates increase with temperature except in experiments involving granitic groundwater. Dissolution rates were generally greater under acid or basic conditions than near neutral pH

Mixed gamma emitting gas standard and method

International Nuclear Information System (INIS)

McFarland, R.C.; McFarland, P.A.

1986-01-01

The invention in one aspect pertains to a method of calibrating gamma spectroscopy systems for gas counting in a variety of counting containers comprising withdrawing a precision volume of a mixed gamma-emitting gas standard from a precision volume vial and delivering the withdrawn precision volume of the gas standard to the interior of a gas counting container. Another aspect of the invention pertains to a mixed gamma-emitting gas standard, comprising a precision spherical vial of predetermined volume, multiple mixed emitting gas components enclosed within the vial, and means for withdrawing from the vial a predetermined amount of the components wherein the gas standard is used to calibrate a gamma spectrometer system for gas counting over a wide energy range without the use of additional standards. A third aspect comprehends a gamma spectrometer calibration system for gas counting, comprising a precision volume spherical glass vial for receiving mixed multiisotope gas components, and two tubular arms extending from the vial. A ground glass stopcock is positioned on each arm, and the outer end of one arm is provided with a rubber septum port

Desarrollo de proyectos viales y aportes del estado en terrenos

OpenAIRE

Beatriz Marulanda; Miguel Montes

2004-01-01

Este artículo tiene como objetivo central identificar las condiciones bajo las cuales es factible que el aporte estatal a un proyecto vial (en el contexto de asociaciones público privadas) esté representado por cesión de terrenos y derechos de uso exclusivo de los mismos en zonas aledañas a una carretera concesionada. En el desarrollo del trabajo, se busca, en particular: 1) Identificar los aspectos críticos que se deben prever para organizar los concursos, valorar y negociar los aportes públ...

Hacia el desarrollo sostenible en la seguridad vial : el caso holandés.

NARCIS (Netherlands)

Wegman, F.C.M.

1999-01-01

En esta ponencia, se hace un estudio general sobre la Seguridad Vial en los Países Bajos, mostrando la evolución del indice de accidentes. Se indican cuales son los objetivos fijados por el Gobierno neerlandés y la estrategia a seguir desde el punto de vista político. Aparece el concepto de

Dissolution of short and long rockwool and glasswool fibers by macrophages in flowthrough cell culture.

Science.gov (United States)

Luoto, K; Holopainen, M; Kangas, J; Kalliokoski, P; Savolainen, K

1998-07-01

Dissolution of MMVF (man-made vitreous fibers) by macrophages has previously been studied utilizing cell cultures in wells. A new, more dynamic method has been developed to explore the effects of macrophages on MMVF dissolution. In this method, the culture medium flows through a membrane on which the macrophages and fibers are placed. The dissolution of short and long rockwool and glasswool fibers was investigated in the present study by macrophages by assessing the dissolution of Si (silicon), Fe (iron), and Al (aluminium) from the fibers. Dissolution of these elements usually increased as a function of time. Generally, the dissolution of elements from the fibers in the flowthrough culture exceeded that observed with the culture in wells system. The dissolution of glasswool fibers was greater in medium than in cell culture, whereas the opposite was true for rockwool fibers. Dissolution of Si was greater from glasswool than from rockwool fibers, while the opposite was true for Fe and Al. Macrophages that had phagocytized fibers in flowthrough culture contained Si, and there were also precipitations with Si in the samples. The fibers in the flowthrough culture also exhibited surface changes such as breakings, pittings, etching, and peeling. The short rockwool fibers tended to fracture more than short glasswool fibers, while long glasswool fibers were more extensively broken than short glasswool fibers. The results with this new, dynamic, flowthrough culture method with macrophages demonstrate that this method provides valuable information on the abilities of macrophages to dissolve MMVF leading to subsequent morphological changes of fibers.

Dissolution of artemisinin/polymer composite nanoparticles fabricated by evaporative precipitation of nanosuspension.

Science.gov (United States)

Kakran, Mitali; Sahoo, Nanda Gopal; Li, Lin; Judeh, Zaher

2010-04-01

An evaporative precipitation of nanosuspension (EPN) method was used to fabricate composite particles of a poorly water-soluble antimalarial drug, artemisinin, with a hydrophilic polymer, polyethylene glycol (PEG), with the aim of enhancing the dissolution rate of artemisinin. We investigated the effect of polymer concentration on the physical, morphological and dissolution properties of the EPN-prepared artemisinin/PEG composites. The original artemisinin powder, EPN-prepared artemisinin nanoparticles and artemisinin/PEG composites were characterised by scanning electron microscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry (DSC), X-ray diffraction (XRD), dissolution testing and HPLC. The percentage dissolution efficiency, relative dissolution, time to 75% dissolution and mean dissolution time were calculated. The experimental drug dissolution data were fitted to various mathematical models (Weibull, first-order, Korsemeyer-Peppas, Hixson-Crowell cube root and Higuchi models) in order to analyse the release mechanism. The DSC and XRD studies suggest that the crystallinity of the EPN-prepared artemisinin decreased with increasing polymer concentration. The phase-solubility studies revealed an A(L)-type curve, indicating a linear increase in drug solubility with PEG concentration. The dissolution rate of the EPN-prepared artemisinin and artemisinin/PEG composites increased markedly compared with the original artemisinin powder. EPN can be used to prepare artemisinin nanoparticles and artemisinin/PEG composite particles that have a significantly enhanced dissolution rate. The mechanism of drug release involved diffusion and erosion.

Dissolution rate effect upon lyolumenescence of irradiated potassium chloride

International Nuclear Information System (INIS)

Leshchinskij, B.L.; Dzelme, Yu.R.; Tiliks, Yu.E.; Bugaenko, L.T.

1985-01-01

The paper is aimed at studying dissolution rate effect and concentration of electron acceptor upon lyoluminescence (LL) that occurs during dissolution of solids with radiation defects. For investigation gamma-irradiated potassium chloride monocrystalline disks were used. As a solvent 3x10sup(-6) M solution of C(RH) hodamine in 2.7 KCl aqueous solution is used. It is shown that LL occurs as a result of recombination of radiation defects with the solution and between themselves in two different regions of subsurface layer of the solid. Investigated dependences of LL intensty on dissolution rate are the efficient method of studying the structure of solids-aqueous solution interface and LL mechanism

Solid dispersions, part I: recent evolutions and future opportunities in manufacturing methods for dissolution rate enhancement of poorly water-soluble drugs.

Science.gov (United States)

Bikiaris, Dimitrios N

2011-11-01

In recent years, the number of active pharmaceutical ingredients with high therapeutic impact, but very low water solubility, has increased significantly. Thus, a great challenge for pharmaceutical technology is to create new formulations and efficient drug-delivery systems to overcome these dissolution problems. Drug formulation in solid dispersions (SDs) is one of the most commonly used techniques for the dissolution rate enhancement of poorly water-soluble drugs. Generally, SDs can be defined as a dispersion of active ingredients in molecular, amorphous and/or microcrystalline forms into an inert carrier. This review covers literature which states that the dissolution enhancement of SDs is based on the fact that drugs in the nanoscale range, or in amorphous phase, dissolve faster and to a greater extent than micronized drug particles. This is in accordance to the Noyes-Whitney equation, while the wetting properties of the used polymer may also play an important role. The main factors why SD-based pharmaceutical products on the market are steadily increasing over the last few years are: the recent progress in various methods used for the preparation of SDs, the effect of evolved interactions in physical state of the drug and formulation stability during storage, the characterization of the physical state of the drug and the mechanism of dissolution rate enhancement.

The Relationship Between the Evolution of an Internal Structure and Drug Dissolution from Controlled-Release Matrix Tablets.

Science.gov (United States)

Kulinowski, Piotr; Hudy, Wiktor; Mendyk, Aleksander; Juszczyk, Ewelina; Węglarz, Władysław P; Jachowicz, Renata; Dorożyński, Przemysław

2016-06-01

In the last decade, imaging has been introduced as a supplementary method to the dissolution tests, but a direct relationship of dissolution and imaging data has been almost completely overlooked. The purpose of this study was to assess the feasibility of relating magnetic resonance imaging (MRI) and dissolution data to elucidate dissolution profile features (i.e., kinetics, kinetics changes, and variability). Commercial, hydroxypropylmethyl cellulose-based quetiapine fumarate controlled-release matrix tablets were studied using the following two methods: (i) MRI inside the USP4 apparatus with subsequent machine learning-based image segmentation and (ii) dissolution testing with piecewise dissolution modeling. Obtained data were analyzed together using statistical data processing methods, including multiple linear regression. As a result, in this case, zeroth order release was found to be a consequence of internal structure evolution (interplay between region's areas-e.g., linear relationship between interface and core), which eventually resulted in core disappearance. Dry core disappearance had an impact on (i) changes in dissolution kinetics (from zeroth order to nonlinear) and (ii) an increase in variability of drug dissolution results. It can be concluded that it is feasible to parameterize changes in micro/meso morphology of hydrated, controlled release, swellable matrices using MRI to establish a causal relationship between the changes in morphology and drug dissolution. Presented results open new perspectives in practical application of combined MRI/dissolution to controlled-release drug products.

Risk of Injection-Site Abscess among Infants Receiving a Preservative-Free, Two-Dose Vial Formulation of Pneumococcal Conjugate Vaccine in Kenya

Science.gov (United States)

Burton, Deron C.; Bigogo, Godfrey M.; Audi, Allan O.; Williamson, John; Munge, Kenneth; Wafula, Jackline; Ouma, Dominic; Khagayi, Sammy; Mugoya, Isaac; Mburu, James; Muema, Shadrack; Bauni, Evasius; Bwanaali, Tahreni; Feikin, Daniel R.; Ochieng, Peter M.; Mogeni, Ondari D.; Otieno, George A.; Olack, Beatrice; Kamau, Tatu; Van Dyke, Melissa K.; Chen, Robert; Farrington, Paddy; Montgomery, Joel M.; Breiman, Robert F.; Scott, J. Anthony G.; Laserson, Kayla F.

2015-01-01

There is a theoretical risk of adverse events following immunization with a preservative-free, 2-dose vial formulation of 10-valent-pneumococcal conjugate vaccine (PCV10). We set out to measure this risk. Four population-based surveillance sites in Kenya (total annual birth cohort of 11,500 infants) were used to conduct a 2-year post-introduction vaccine safety study of PCV10. Injection-site abscesses occurring within 7 days following vaccine administration were clinically diagnosed in all study sites (passive facility-based surveillance) and, also, detected by caregiver-reported symptoms of swelling plus discharge in two sites (active household-based surveillance). Abscess risk was expressed as the number of abscesses per 100,000 injections and was compared for the second vs first vial dose of PCV10 and for PCV10 vs pentavalent vaccine (comparator). A total of 58,288 PCV10 injections were recorded, including 24,054 and 19,702 identified as first and second vial doses, respectively (14,532 unknown vial dose). The risk ratio for abscess following injection with the second (41 per 100,000) vs first (33 per 100,000) vial dose of PCV10 was 1.22 (95% confidence interval [CI] 0.37–4.06). The comparator vaccine was changed from a 2-dose to 10-dose presentation midway through the study. The matched odds ratios for abscess following PCV10 were 1.00 (95% CI 0.12–8.56) and 0.27 (95% CI 0.14–0.54) when compared to the 2-dose and 10-dose pentavalent vaccine presentations, respectively. In Kenya immunization with PCV10 was not associated with an increased risk of injection site abscess, providing confidence that the vaccine may be safely used in Africa. The relatively higher risk of abscess following the 10-dose presentation of pentavalent vaccine merits further study. PMID:26509274

Evaluating the role of re-adsorption of dissolved Hg{sup 2+} during cinnabar dissolution using isotope tracer technique

Energy Technology Data Exchange (ETDEWEB)

Jiang, Ping [Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199 (United States); Li, Yanbin [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education/Qingdao Collaborative Innovation Center of Marine Science and Technology, Ocean University of China, Qingdao 266100 (China); Liu, Guangliang [Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199 (United States); Southeast Environmental Research Center, Florida International University, Miami, FL 33199 (United States); Yang, Guidi [College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002 (China); Lagos, Leonel [Applied Research Center, Florida International University, Miami, FL 33199 (United States); Yin, Yongguang [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Gu, Baohua [Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge TN 37831 (United States); Jiang, Guibin [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Cai, Yong, E-mail: cai@fiu.edu [Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199 (United States); Southeast Environmental Research Center, Florida International University, Miami, FL 33199 (United States)

2016-11-05

Highlights: • Develop a new method to study Hg re-adsorption in cinnabar. • Both isotope dilution and tracer techniques were adopted. • The presence of O{sub 2} can significantly enhance the dissolution of cinnabar. • Prove the necessity of including re-adsorption in estimating cinnabar dissolution. - Abstract: Cinnabar dissolution is an important factor controlling mercury (Hg) cycling. Recent studies have suggested the co-occurrence of re-adsorption of the released Hg during the course of cinnabar dissolution. However, there is a lack of feasible techniques that can quantitatively assess the amount of Hg re-adsorbed on cinnabar when investigating cinnabar dissolution. In this study, a new method, based on isotope tracing and dilution techniques, was developed to study the role of Hg re-adsorption in cinnabar dissolution. The developed method includes two key components: (1) accurate measurement of both released and spiked Hg in aqueous phase and (2) estimation of re-adsorbed Hg on cinnabar surface via the reduction in spiked {sup 202}Hg{sup 2+}. By adopting the developed method, it was found that the released Hg for trials purged with oxygen could reach several hundred μg L{sup −1}, while no significant cinnabar dissolution was detected under anaerobic condition. Cinnabar dissolution rate when considering Hg re-adsorption was approximately 2 times the value calculated solely with the Hg detected in the aqueous phase. These results suggest that ignoring the Hg re-adsorption process can significantly underestimate the importance of cinnabar dissolution, highlighting the necessity of applying the developed method in future cinnabar dissolution studies.

Effect of dissolution kinetics on flotation response of calcite with oleate

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D. G. Horta

Full Text Available Abstract Phosphate flotation performance can be influenced by the dissolution kinetics of the minerals that compose the ore. The purpose of this work was to investigate the effect of dissolution kinetics on flotation response with oleate (collector of calcites from different origins and genesis. The calcite samples were first purified and characterized by x-ray Fluorescence (XRF and the Rietveld method applied to x-ray Diffractometry data (RXD. Experiments of calcite dissolution and microflotationwere performed at pH 8 and pH 10.The pH effect on the calcite dissolution and flotation indicates the possible influence of the carbonate/bicarbonate ions provided by the CO2 present in the air. In addition, the flotation response is greater as the dissolution increases, making more Ca2+ ions available to interact with collector molecules. This result corroborates the surface precipitation mechanism proposed foroleate adsorption on the calcite surface.

Medición de microdeformaciones en losas viales usando sensores de redes de Braggen fibras ópticas Microdeformation measurement of concrete roadway slabs using fiber Bragg gratings

Directory of Open Access Journals (Sweden)

Francisco Javier Vélez Hoyos

2010-06-01

Full Text Available En este trabajo se presenta un método no invasivo para la medición de microdeformaciones en estructuras de concreto usando sensores de redes de Bragg en fibras ópticas adheridos a su superficie. Se realizan mediciones en losas viales de concreto bajo una carga estática de 10 kN, encontrándose una relación aproximada de 2 : 1 entre la deformación registrada por los sensores y los valores arrojados por una simulación computacional con el método de elementos finitos. Se propone el uso de estos sensores para el monitoreo estructural de losas en una malla vial con sensores distribuidos y multiplexados por longitud de onda. Este es el primer reporte en Colombia de medición de deformación de losas viales usando sensores de fibra óptica.This work shows a non–invasive method for micro–deformation measurements of concrete structures using Bragg grating sensors in optical fibers adhered to the surface. Measurements on roadway slabs under a 10 kN static load are made, finding an approximated ratio of 2 : 1 between the deformation registered by the sensors and the values from a computational simulation with the finite element method. We propose the use of these sensors for slab structural monitoring in a road network employing distributed and wavelength multiplexed sensors. This is a first report in Colombia of roadway slabs microdeformation measurement using fiber optic sensors.

The dissolution phenomenon of lysozyme crystals

Energy Technology Data Exchange (ETDEWEB)

Mueller, C.; Ulrich, J. [Martin Luther University Halle-Wittenberg, Department of Thermal Separation Processes, Centre of Engineering Science, Halle/Saale (Germany)

2012-02-15

Dissolution studies on lysozyme crystals were carried out since the observed dissolution pattern look different from non-protein dissolved crystals. The Tetragonal, High Temperature and Low Temperature Orthorhombic morphologies, crystallized using sodium chloride, were chosen and the influence of different pH, salt and protein concentration on their dissolution was investigated. An increase in pH and/or salt concentration can modify the dissolution behaviour. The pattern of the crystals during the dissolution process will, therefore, develop differently. Frequently a skeleton like crystal pattern followed by a falling apart of the crystals is observed. The multi-component character of the lysozyme crystal (protein, water, buffer, salt) as well as ''solvatomorphism'' gives first insights in the phenomena happening in the dissolution process. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Effect of Air Space in Storage Vials on Motility of Spermatozoa in Chilled Buck Semen

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Magnus Paul K and Lali F Anand 1

Full Text Available This study was conducted in order to find out the effect of air space on the top of glass vial in which semen is stored, on the motility of spermatozoa. 45 samples collected from two bucks over a span of 6 months were used for experiment. Goat milk extender was the diluent used. Two ml each of diluted semen after noting their initial motility was stored in 2 ml and 5 ml vials. Samples were stored at 5°C and motility of spermatozoa noted at 24 and 48 hours. Semen without air space was found to preserve the motility better than semen with air space on 24 and 48 hours of incubation. This could be better attributed to reactive oxygen species production by the spermatozoa, but further investigation is needed in this aspect to confirm it. [Veterinary World 2010; 3(9.000: 421-423

Bench Scale Saltcake Dissolution Test Report

International Nuclear Information System (INIS)

BECHTOLD, D.B.; PACQUET, E.A.

2000-01-01

A potential scenario for retrieving saltcake from single shell tanks is the ''Rainbird(reg s ign) sprinkler'' method. Water is distributed evenly across the surface of the saltcake and allowed to percolate by gravity through the waste. The salt dissolves in the water, forming a saturated solution. The saturated liquid is removed by a saltwell pump situated near the bottom of the tank. By this method, there is never a large inventory of liquid in the tank that could pose a threat of leakage. There are many variables or factors that can influence the hydrodynamics of this retrieval process. They include saltcake porosity; saltwell pumping rate; salt dissolution chemistry; factors that could promote flow channeling (e.g. tank walls, dry wells, inclusions or discontinuities in the saltcake); method of water distribution; plug formation due to crystal formations or accumulation of insoluble solids. A brief literature search indicates that very little experimental data exist on these aspects of saltcake dissolution (Wiersma 1996, 1997). The tests reported here were planned (Herting, 2000) to provide preliminary data and information for planning future, scaled-up tests of the sprinkler method

UV imaging for in vitro dissolution and release studies: Initial experiences

DEFF Research Database (Denmark)

Østergaard, Jesper; Lenke, James; Jensen, Sabrine Smedegaard

2014-01-01

UV imaging has recently been introduced as a method in drug dissolution and release testing. Spatially and temporally resolved mapping of drug oncentrations in a 7 × 9 mm imaging area provides new opportunities for visualization and study of drug dissolution and release. This review describes...... in hydrogels with relevance for characterization of parenteral depots. UV imaging may be of particular use when the amounts of material are sparse and detailed insights into dissolution and release processes are required, that is in solid form screening, preformulation, and early drug development....

Evaluating the role of re-adsorption of dissolved Hg(2+) during cinnabar dissolution using isotope tracer technique.

Science.gov (United States)

Jiang, Ping; Li, Yanbin; Liu, Guangliang; Yang, Guidi; Lagos, Leonel; Yin, Yongguang; Gu, Baohua; Jiang, Guibin; Cai, Yong

2016-11-05

Cinnabar dissolution is an important factor controlling mercury (Hg) cycling. Recent studies have suggested the co-occurrence of re-adsorption of the released Hg during the course of cinnabar dissolution. However, there is a lack of feasible techniques that can quantitatively assess the amount of Hg re-adsorbed on cinnabar when investigating cinnabar dissolution. In this study, a new method, based on isotope tracing and dilution techniques, was developed to study the role of Hg re-adsorption in cinnabar dissolution. The developed method includes two key components: (1) accurate measurement of both released and spiked Hg in aqueous phase and (2) estimation of re-adsorbed Hg on cinnabar surface via the reduction in spiked (202)Hg(2+). By adopting the developed method, it was found that the released Hg for trials purged with oxygen could reach several hundred μgL(-1), while no significant cinnabar dissolution was detected under anaerobic condition. Cinnabar dissolution rate when considering Hg re-adsorption was approximately 2 times the value calculated solely with the Hg detected in the aqueous phase. These results suggest that ignoring the Hg re-adsorption process can significantly underestimate the importance of cinnabar dissolution, highlighting the necessity of applying the developed method in future cinnabar dissolution studies. Copyright © 2016 Elsevier B.V. All rights reserved.

Assessing the effect of dissolved organic ligands on mineral dissolution rates: An example from calcite dissolution

International Nuclear Information System (INIS)

DeMaio, T.; Grandstaff, D.E.

1997-01-01

Experiments suggest that dissolved organic ligands may primarily modify mineral dissolution rates by three mechanisms: (1) metal-ligand (M-L) complex formation in solution, which increases the degree of undersaturation, (2) formation of surface M-L complexes that attack the surface, and (3) formation of surface complexes which passivate or protect the surface. Mechanisms (1) and (2) increase the dissolution rate and the third decreases it compared with organic-free solutions. The types and importance of these mechanisms may be assessed from plots of dissolution rate versus degree of undersaturation. To illustrate this technique, calcite, a common repository cementing and vein-filling mineral, was dissolved at pH 7.8 and 22 C in Na-Ca-HCO 3 -Cl solutions with low concentrations of three organic ligands. Low citrate concentrations (50 microM) increased the dissolution rate consistent with mechanism (1). Oxalate decreased the rate, consistent with mechanism (3). Low phthalate concentration (<50 microM) decreased calcite dissolution rates; however, higher concentrations increased the dissolution rates, which became faster than in inorganic solutions. Thus, phthalate exhibits both mechanisms (2) and (3) at different concentrations. In such cases linear extrapolations of dissolution rates from high organic ligand concentrations may not be valid

Collective dissolution of microbubbles

Science.gov (United States)

Michelin, Sébastien; Guérin, Etienne; Lauga, Eric

2018-04-01

A microscopic bubble of soluble gas always dissolves in finite time in an undersaturated fluid. This diffusive process is driven by the difference between the gas concentration near the bubble, whose value is governed by the internal pressure through Henry's law, and the concentration in the far field. The presence of neighboring bubbles can significantly slow down this process by increasing the effective background concentration and reducing the diffusing flux of dissolved gas experienced by each bubble. We develop theoretical modeling of such diffusive shielding process in the case of small microbubbles whose internal pressure is dominated by Laplace pressure. We first use an exact semianalytical solution to capture the case of two bubbles and analyze in detail the shielding effect as a function of the distance between the bubbles and their size ratio. While we also solve exactly for the Stokes flow around the bubble, we show that hydrodynamic effects are mostly negligible except in the case of almost-touching bubbles. In order to tackle the case of multiple bubbles, we then derive and validate two analytical approximate yet generic frameworks, first using the method of reflections and then by proposing a self-consistent continuum description. Using both modeling frameworks, we examine the dissolution of regular one-, two-, and three-dimensional bubble lattices. Bubbles located at the edge of the lattices dissolve first, while innermost bubbles benefit from the diffusive shielding effect, leading to the inward propagation of a dissolution front within the lattice. We show that diffusive shielding leads to severalfold increases in the dissolution time, which grows logarithmically with the number of bubbles in one-dimensional lattices and algebraically in two and three dimensions, scaling respectively as its square root and 2 /3 power. We further illustrate the sensitivity of the dissolution patterns to initial fluctuations in bubble size or arrangement in the case

Dissolution enthalpy of sodium sulfacetamide in water: comparison between solution isoperibolic calorimetry and the van't Hoff method

OpenAIRE

Torres, Daniel R.; Sosnik, Alejandro; Chiappetta, Diego; Vargas, Edgar F.; Martínez, Fleming

2008-01-01

The dissolution enthalpy (ΔH0soln) of sodium sulfacetamide in water was determined by means of isoperibolic solution calorimetry. It was found that ΔH0soln diminishes as the drug concentration increases. Otherwise, the calorimetric values obtained as a function of the drug concentration were significantly different than those predicted by the van't Hoff method. It was demonstrated that the later is not a fully reliable method for the determination of ΔH0soln values in the speci...

Dissolution test of herbal medicines containing Passiflora sp.

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Ane R. T. Costa

2011-05-01

Full Text Available The dissolution test is an essential tool to assess the quality of herbal medicines in the solid dosage form for oral use. This work aimed to evaluate the dissolution behavior of three herbal medicines in the form of capsules and tablet containing Passiflora, produced with powder or dried extract. Assay of total flavonoids and dissolution methods were validated and obtained results allowed the quantification of flavonoids with precision, accuracy and selectivity. The percentage of total flavonoids found was 2% for capsule A (containing only powder, 0.97% for capsule B (containing only dried extract and 5.5% for tablet. Although the content was lower, the release of flavonoids present in the capsule containing dried extract was 12% higher over 30 min, with dissolved percentage values of 87 and 75, for the capsules containing extract and powder, respectively. The tablet containing dried extract presented dissolution of 76%, despite the higher content of flavonoids, which may be due to pharmacotechnical problems. Obtained data demonstrated the need to implement these tests in the quality control of herbal medicines, confirming the release of the active ingredients that underlie the pharmacological action of these medicines.

Computational fluid dynamics (CFD) studies of a miniaturized dissolution system.

Science.gov (United States)

Frenning, G; Ahnfelt, E; Sjögren, E; Lennernäs, H

2017-04-15

Dissolution testing is an important tool that has applications ranging from fundamental studies of drug-release mechanisms to quality control of the final product. The rate of release of the drug from the delivery system is known to be affected by hydrodynamics. In this study we used computational fluid dynamics to simulate and investigate the hydrodynamics in a novel miniaturized dissolution method for parenteral formulations. The dissolution method is based on a rotating disc system and uses a rotating sample reservoir which is separated from the remaining dissolution medium by a nylon screen. Sample reservoirs of two sizes were investigated (SR6 and SR8) and the hydrodynamic studies were performed at rotation rates of 100, 200 and 400rpm. The overall fluid flow was similar for all investigated cases, with a lateral upward spiraling motion and central downward motion in the form of a vortex to and through the screen. The simulations indicated that the exchange of dissolution medium between the sample reservoir and the remaining release medium was rapid for typical screens, for which almost complete mixing would be expected to occur within less than one minute at 400rpm. The local hydrodynamic conditions in the sample reservoirs depended on their size; SR8 appeared to be relatively more affected than SR6 by the resistance to liquid flow resulting from the screen. Copyright © 2017 Elsevier B.V. All rights reserved.

Modelling of the UO2 dissolution mechanisms in synthetic groundwater solutions. Dissolution experiments carried out under oxic conditions

International Nuclear Information System (INIS)

Cera, E.; Grive, M.; Bruno, J.; Ollila, K.

2001-02-01

The analytical data generated during the last three years within the 4th framework program of the European Community at VTT Chemical Technology concerning UO 2 dissolution under oxidising conditions have been modelled in the present work. The modelling work has been addressed to perform a kinetic study of the dissolution data generated by Ollila (1999) under oxidising conditions by using unirradiated uranium dioxide as solid sample. The average of the normalised UO 2 dissolution rates determined by using the initial dissolution data generated in all the experimental tests is (6.06 ± 3.64)* 10 -7 mol m -2 d -1 . This dissolution rate agrees with most of the dissolution rates reported in the literature under similar experimental conditions. The results obtained in this modelling exercise show that the same bicarbonate promoted oxidative dissolution processes operate for uranium dioxide, as a chemical analogue of the spent fuel matrix, independently of the composition of the aqueous solution used. (orig.)

Peroxide formation and kinetics of sodium dissolution in alcohols

International Nuclear Information System (INIS)

Muralidaran, P.; Chandran, K.; Ganesan, V.; Periaswami, G.

1997-01-01

Suitable techniques for sodium removal and decontamination of sodium wetted components of Liquid Metal Fast Reactors (LMFRs) are necessary both for repair, reuse and decommissioning of such components. Among the methods followed for sodium removal, alcohol dissolution is usually employed for small components like bellow sealed valves, gripping tools to handle core components and sodium sampling devices (primary and secondary). One of the concerns in the alcohol dissolution method is the possible role of peroxide formation in the ethoxy group during storage and handling leading to explosion. This paper describes the study of peroxide formation in ethyl carbitol and butyl cellosolve as well as some of the results of dissolution kinetic studies carried out in our laboratory using different alcohols. The peroxide formation of ethyl carbitol and butyl cellosolve were studied by iodometric technique. It has been found that the peroxide formation is less in sodium containing alcohol than in pure one. Ethyl carbitol, butyl cellosolve and Jaysol-SS (mixture of ethyl alcohol, methyl alcohol, isopropyl alcohol and methyl isobutyl ketone) were used in dissolution kinetics studies. The effects due to area and orientation of the fresh sodium surface have also been investigated. The reaction rates were studied in the temperature range of 303-343 K. The rate of dissolution was estimated by measuring the sodium content of alcohol at periodic intervals. It is found that the reaction rate varies in the order of ethyl alcohol-water mixture > Jaysol-SS > butyl cellosolve > ethyl carbitol. While cleaning sodium using alcohol, the concentration of alcohol is held essentially constant throughout the process. The rate of reaction depends only on the amount of sodium and follows pseudo-first order kinetics. Increase in surface area has a marked impact on the dissolution rate at lower temperatures while at higher temperatures, the temperature factor overrides the effect due to surface area

PROPUESTA DE PROCEDIMIENTOS DE AUTOCONTROL EN CONTRATOS DE CONSERVACIÓN DE UNA RED VIAL

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R. F. Herrera

2016-12-01

Full Text Available Con un contrato global mixto se lleva a cabo la mantención de una red vial, a través de la ejecución simultánea de conservación bajo la modalidad a serie de precios unitarios, y bajo suma alzada por nivel de servicio. En estos últimos se evidencia una mayor precariedad en los procedimientos, debido a fallas en la visión de la empresa contratista en asumir la gestión de la conservación, carencia en la asignación de responsabilidades a los miembros del equipo, y el deficiente control de la calidad de las obras y documentación del contrato. Por este motivo, en este trabajo se realiza una propuesta de gestión definiendo cada una de las etapas que la componen, con la finalidad de asegurar una correcta conservación de los elementos que conforman la infraestructura vial. Los objetivos propuestos son: especificar la metodología a usar para gestionar la mantención de la red contratada bajo la modalidad global mixto, especificar el manejo y control de la documentación que deben mantener en el contrato, y definir las aptitudes y responsabilidades del equipo de trabajo. Para cumplir con los mismos se realizó una revisión bibliográfica de la normativa nacional acerca de la mantención de caminos, y se tomó conocimiento de la diversidad de contratos que utiliza la Dirección de Vialidad para la conservación vial. Además, a través de la experiencia en contratos de conservación global mixto se definen las aptitudes y responsabilidades que se recomienda que tengan los miembros del equipo de trabajo.

Surface controlled dissolution rates of gypsum in aqueous solutions exhibit nonlinear dissolution kinetics

Science.gov (United States)

Jeschke, Alexander A.; Vosbeck, Katrin; Dreybrodt, Wolfgang

2001-01-01

The effective dissolution rates of gypsum are determined by mixed kinetics, where the rate constants of dissolution at the surface and the transport constant of molecular diffusion of dissolved material are similar. To obtain the surface reaction rate law it is necessary to know the transport constant. We have determined the surface rate law for monocrystalline selenite by using a rotating disc set-up, where the transport coefficients are well known. As a result, up to a calcium concentration of 0.6 · ceq, we find a nearly linear rate law Rs = ksl (1- cs/ ceq) n1, where cs is the total calcium concentration at the surface and ceq the equilibrium concentration with respect to gypsum, n1 = 1.2 ± 0.2, and ksl = 1.1 · 10 -4 mmol cm -2 s -1 ± 15%. We also employed batch-experiments for selenite, alabaster and gypsum rock samples. The result of these experiments were interpreted by using a transport constant determined by NaCl dissolution experiments under similar physical conditions. The batch experiments reveal a dissolution rate law Rs = ksl (1- cs/ ceq) n1, ksl = 1.3 · 10 -4 mmol · cm -2 s -1, n1 = 1.2 ± 0.2 for c ≤ 0.94 · ceq. Close to equilibrium a nonlinear rate law, Rs = ks2 (1- cs/ ceq) n2, is observed, where ks2 is in the order of 10 mmol · cm -2 s -1 and n2 ≈ 4.5. The experimentally observed gypsum dissolution rates from the batch experiments could be accurately fitted, with only minor variations of the surface reaction constant obtained from the rotating disk experiment and the transport coefficient from the NaCl dissolution batch experiment. Batch experiments on pure synthetic gypsum, reveal a linear rate law up to equilibrium. This indicates inhibition of dissolution in natural samples close to equilibrium, as is known also for calcite minerals.

Development and validation of a dissolution test for diltiazem hydrochloride in immediate release capsules

Directory of Open Access Journals (Sweden)

Taciane Ferreira Mendonça

2011-01-01

Full Text Available This work describes the development and validation of a dissolution test for 60 mg of diltiazem hydrochloride in immediate release capsules. The best dissolution in vitro profile was achieved using potassium phosphate buffer at pH 6.8 as the dissolution medium and paddle as the apparatus at 50 rpm. The drug concentrations in the dissolution media were determined by UV spectrophotometry and HPLC and a statistical analysis revealed that there were significant differences between HPLC and spectrophotometry. This study illustrates the importance of an official method for the dissolution test, since there is no official monograph for diltiazem hydrochloride in capsules.

Shell Vial culture Assay for the rapid diagnosis of Japanese encephalitis, West Nile and Dengue-2 viral encephalitis

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Badrinath S

2006-01-01

Full Text Available Abstract Background Encephalitis caused by flaviviruses, Japanese encephalitis virus (JEV and West Nile virus (WNV is responsible for significant morbidity and mortality in many endemic countries. Dengue-2 (Den-2 virus is a recent addition to the list of encephalitogenic viruses, after its Central Nervous System (CNS invasion capability has been established. There is a wide array of laboratory tools that have helped us not only in the diagnosis of these conditions but also in understanding their pathogenesis and pathology. However, there are no reports of Shell Vial Culture (SVC, a centrifuge enhanced tissue culture assay that has revolutionized viral culturing in terms of rapidity and sensitivity being optimized for these flaviviral encephalitic conditions. The present study is an attempt to standardize and evaluate the usefulness of SVC for the laboratory diagnosis of JE, WN and Den-2 encephalitis cases and to compare it with Indirect Immunofluorescence (IIF technique that detects cell associated virus antigen. Analysis of the various clinical parameters with respect to viral etiology has also been carried out. Results Pediatric patients constituted the major group involved in the study (92%. Etiological diagnosis of viral encephalitis could be established in twenty nine (58% patients. JE encephalitis was the commonest with 19 (39% cases being positive followed by, WN (9 cases-18% and Den-2 (one case. IIF test could detect antigens of JE, WN and Den-2 viruses in 16(32%, 7(14% and 1 case respectively. Shell vial culture assay picked up all cases that were positive by IIF test. In addition, SVC assay could detect 3 and 2 more cases of JE and WN encephalitis respectively, that were negative by the IIF test. Conclusion Shell vial culture is a rapid and efficient tool for the etiological diagnosis of JE, WN and Den-2 encephalitis cases. Early, prompt collection, transport and processing of the CSF samples, would make SVC a better method for the

Measurement of low-level beta activity of samples in liquid state using plastic scintillator vials

International Nuclear Information System (INIS)

Wezranowski, E.; Panczyk, E.; Radwan, M.

1977-01-01

Plastic scintillation vials having walls from a plastic scintillator and the bottom from perspex were used. Wall thickness was 0.8 to 3 mm. The solution radioactivity was measured by a scintillation beta spectrometer. The total measurement errors were found for the following radionuclides: 14 C +-3.7%; 204 Tl +-3%; 32 P +-2.8%; 137 Cs +-2%, and 72 Ga +-5%. Detection efficiency was found to decrease rapidly with the solution layer thickness. For a solution thickness of 0.2 mm the highest detection efficiency was observed with the 4% measurement error. Linear dependence was found of detection efficiency on beta energy. For a solution layer thickness of 0.2 mm the minimum measurable activities were determined to be 30.3 pCi for 14 C and 2.12 pCi for 32 P. The use of the above vials permits quick and simple measurement without sample chemical preparation. (J.P.)

Effects of Surface Composition on the Aerosolisation and Dissolution of Inhaled Antibiotic Combination Powders Consisting of Colistin and Rifampicin

DEFF Research Database (Denmark)

Wang, Wenbo; Zhou, Qi Tony; Sun, Si-Ping

2016-01-01

is hygroscopic and rifampicin is hydrophobic, moisture absorption of combination formulations was significantly lower than the pure colistin formulation in the dynamic vapour sorption results. To investigate the dissolution characteristics, four dissolution test methods (diffusion Franz cell, modified Franz cell......, flow-through and beaker methods) were employed and compared. The modified Franz cell method was selected to test the dissolution behaviour of aerosolised powder formulations to eliminate the effect of membrane on dissolution. The results showed that surface enrichment of hydrophobic rifampicin neither...

Development of a numerical simulation method for melting/solidification and dissolution/precipitation phenomena. 1. Literature survey for computer program design

International Nuclear Information System (INIS)

Uchibori, Akihiro; Ohshima, Hiroyuki

2004-04-01

Survey research of numerical methods for melting/solidification and dissolution/precipitation phenomena was performed to determine the policy for a simulation program development. Melting/solidification and dissolution/ precipitation have been key issues for feasibility evaluation of several techniques applied in the nuclear fuel cycle processes. Physical models for single-component melting/solidification, two-component solution solidification or precipitation by cooling and precipitation by electrolysis, which are moving boundary problems, were made clear from the literature survey. The transport equations are used for thermal hydraulic analysis in the solid and the liquid regions. Behavior of the solid-liquid interface is described by the heat and mass transfer model. These physical models need to be introduced into the simulation program. The numerical methods for the moving boundary problems are categorized into two types: interface tracking method and interface capturing method. Based on the classification, performance of each numerical method was evaluated. The interface tracking method using the Lagrangian moving mesh requires relatively complicated algorithm. The algorithm has high accuracy for predicting the moving interface. On the other hand, the interface capturing method uses the Eulerian fixing mesh, leading to simple algorithm. Prediction accuracy of the method is relatively low. The extended finite element method classified as the interface capturing method can predict the interface behavior accurately even though the Eulerian fixing mesh is used. We decided to apply the extended finite element method to the simulation program. (author)

Dissolution of minerals with rough surfaces

Science.gov (United States)

de Assis, Thiago A.; Aarão Reis, Fábio D. A.

2018-05-01

We study dissolution of minerals with initial rough surfaces using kinetic Monte Carlo simulations and a scaling approach. We consider a simple cubic lattice structure, a thermally activated rate of detachment of a molecule (site), and rough surface configurations produced by fractional Brownian motion algorithm. First we revisit the problem of dissolution of initial flat surfaces, in which the dissolution rate rF reaches an approximately constant value at short times and is controlled by detachment of step edge sites. For initial rough surfaces, the dissolution rate r at short times is much larger than rF ; after dissolution of some hundreds of molecular layers, r decreases by some orders of magnitude across several time decades. Meanwhile, the surface evolves through configurations of decreasing energy, beginning with dissolution of isolated sites, then formation of terraces with disordered boundaries, their growth, and final smoothing. A crossover time to a smooth configuration is defined when r = 1.5rF ; the surface retreat at the crossover is approximately 3 times the initial roughness and is temperature-independent, while the crossover time is proportional to the initial roughness and is controlled by step-edge site detachment. The initial dissolution process is described by the so-called rough rates, which are measured for fixed ratios between the surface retreat and the initial roughness. The temperature dependence of the rough rates indicates control by kink site detachment; in general, it suggests that rough rates are controlled by the weakest microscopic bonds during the nucleation and formation of the lowest energy configurations of the crystalline surface. Our results are related to recent laboratory studies which show enhanced dissolution in polished calcite surfaces. In the application to calcite dissolution in alkaline environment, the minimal values of recently measured dissolution rate spectra give rF ∼10-9 mol/(m2 s), and the calculated rate

Dissolution process for advanced-PWR-type fuels

International Nuclear Information System (INIS)

Black, D.E.; Decker, L.A.; Pearson, L.G.

1979-01-01

The new Fluorinel Dissolution Process and Fuel Storage (FAST) Facility at ICPP will provide underwater storage of spent PWR fuel and a new head-end process for fuel dissolution. The dissolution will be two-stage, using HF and HNO 3 , with an intermittent H 2 SO 4 dissolution for removing stainless steel components. Equipment operation is described

Affinity functions for modeling glass dissolution rates

Energy Technology Data Exchange (ETDEWEB)

Bourcier, W.L. [Lawrence Livermore National Lab., CA (United States)

1997-07-01

Glass dissolution rates decrease dramatically as glass approach ''saturation'' with respect to the leachate solution. Most repository sites are chosen where water fluxes are minimal, and therefore the waste glass is most likely to dissolve under conditions close to ''saturation''. The key term in the rate expression used to predict glass dissolution rates close to ''saturation'' is the affinity term, which accounts for saturation effects on dissolution rates. Interpretations of recent experimental data on the dissolution behaviour of silicate glasses and silicate minerals indicate the following: 1) simple affinity control does not explain the observed dissolution rate for silicate minerals or glasses; 2) dissolution rates can be significantly modified by dissolved cations even under conditions far from saturation where the affinity term is near unity; 3) the effects of dissolved species such as Al and Si on the dissolution rate vary with pH, temperature, and saturation state; and 4) as temperature is increased, the effect of both pH and temperature on glass and mineral dissolution rates decrease, which strongly suggests a switch in rate control from surface reaction-based to diffusion control. Borosilicate glass dissolution models need to be upgraded to account for these recent experimental observations. (A.C.)

Impact of vibration and agitation speed on dissolution of USP prednisone tablets RS and various IR tablet formulations.

Science.gov (United States)

Seeger, Nicole; Lange, Sigrid; Klein, Sandra

2015-08-01

Dissolution testing is an in vitro procedure which is widely used in quality control (QC) of solid oral dosage forms and, given that real biorelevant test conditions are applied, can also be used as a predictive tool for the in vivo performance of such formulations. However, if a dissolution method is intended to be used for such purposes, it has to deliver results that are only determined by the quality of the test product, but not by other variables. In the recent past, more and more questions were arising on how to address the effects of vibration on dissolution test results. The present study was performed to screen for the correlation of prednisone dissolution of USP Prednisone Tablets RS with vibration caused by a commercially available vibration source as well as to investigate how drug release from a range of immediate release formulations containing class 1-4 drugs of the biopharmaceutical classification scheme is affected by vibration when performing dissolution experiments at different agitation rates. Results of the present study show that the dissolution process of oral drug formulations can be affected by vibration. However, it also becomes clear that the degree of which a certain level of vibration impacts dissolution is strongly dependent on several factors such as drug properties, formulation parameters, and the design of the dissolution method. To ensure the establishment of robust and predictive dissolution test methods, the impact of variation should thus be considered in method design and validation.

The dissolution of chalcopyrite in chloride media

International Nuclear Information System (INIS)

Ibanez, T.; Velasquez, L.

2013-01-01

The aim of this investigation is to determinate the effects of parameters and additives on the kinetics of dissolution of chalcopyrite on moderated conditions by means of dissolutions test with chalcopyrite concentrate and pure chalcopyrite in shake flasks and instrumented stirred reactors. A study of the dissolution of chalcopyrite in chloride solutions has demonstrated that the rate of dissolution of chalcopyrite is strongly dependent on the potential of the solution within a range of 540 to 630 mV (versus SHE). Leaching at pH around 2.5 results in increased rates of copper dissolution suggesting the possibility to keep the solution potential within the range. Both pyrite and silver ions enhance the dissolution of chalcopyrite and this effect increases when both species are present. The MnO 2 has a negative effect on the dissolution increasing the solution potential to values where the rate decreases considerably. (Author)

Designing a dynamic dissolution method: a review of instrumental options and corresponding physiology of stomach and small intestine.

Science.gov (United States)

Culen, Martin; Rezacova, Anna; Jampilek, Josef; Dohnal, Jiri

2013-09-01

Development of new pharmaceutical compounds and dosage forms often requires in vitro dissolution testing with the closest similarity to the human gastrointestinal (GI) tract. To create such conditions, one needs a suitable dissolution apparatus and the appropriate data on the human GI physiology. This review discusses technological approaches applicable in biorelevant dissolutions as well as the physiology of stomach and small intestine in both fasted and fed state, that is, volumes of contents, transit times for water/food and various solid oral dosage forms, pH, osmolality, surface tension, buffer capacity, and concentrations of bile salts, phospholipids, enzymes, and Ca(2+) ions. The information is aimed to provide clear suggestions on how these conditions should be set in a dynamic biorelevant dissolution test. Copyright © 2013 Wiley Periodicals, Inc.

Pilot-scale tests of HEME and HEPA dissolution process

International Nuclear Information System (INIS)

Qureshi, Z.H.; Strege, D.K.

1996-01-01

A series of pilot-scale demonstration tests for the dissolution of High Efficiency Mist Eliminators (BEME's) and High Efficiency Particulate Airfilters (BEPA) were performed on a 1/5th linear scale. These filters are to be used in the Defense Waste Processing Facility (DWPF) to decontaminate the effluents from the off-gases generated during the feed preparation process and vitrification. When removed, these radioactively contaminated filters will be dissolved using caustic solutions. As a result of these tests, a simple dissolution process was developed. In this process, the contaminated filter is first immersed in boiling 5% caustic solution for 24 hours and then water is sprayed on the filter. These steps break down the filter first chemically and then mechanically. The metal cage is rinsed and considered low level waste. The dissolved filter is pumpable and mixed with high level waste. Compared to earlier dissolution studies using caustic-acid-caustic solutions, the proposed method represents a 66% savings in cycle time and amount of liquid waste generated. This paper provides the details of filter mockups and results of the dissolution tests

Dissolution glow curve in LLD

International Nuclear Information System (INIS)

Haverkamp, U.; Wiezorek, C.; Poetter, R.

1990-01-01

Lyoluminescence dosimetry is based upon light emission during dissolution of previously irradiated dosimetric materials. The lyoluminescence signal is expressed in the dissolution glow curve. These curves begin, depending on the dissolution system, with a high peak followed by an exponentially decreasing intensity. System parameters that influence the graph of the dissolution glow curve, are, for example, injection speed, temperature and pH value of the solution and the design of the dissolution cell. The initial peak does not significantly correlate with the absorbed dose, it is mainly an effect of the injection. The decay of the curve consists of two exponential components: one fast and one slow. The components depend on the absorbed dose and the dosimetric materials used. In particular, the slow component correlates with the absorbed dose. In contrast to the fast component the argument of the exponential function of the slow component is independent of the dosimetric materials investigated: trehalose, glucose and mannitol. The maximum value, following the peak of the curve, and the integral light output are a measure of the absorbed dose. The reason for the different light outputs of various dosimetric materials after irradiation with the same dose is the differing solubility. The character of the dissolution glow curves is the same following irradiation with photons, electrons or neutrons. (author)

Liquid scintillation vial for radiometric assay of lymphocyte carbohydrate metabolism in response to mitogens

International Nuclear Information System (INIS)

Tran, N.; Wagner, H.N. Jr.

1978-01-01

We have demonstrated that mitogens--i.e., PHA and Con.A--stimulate lymphocyte carbohydrate metabolism using a liquid-scintillation vial with conventional liquid-scintillation detectors. The results showed that this enclosed system can be useful for development of rapid in vitro tests of lymphocytes immune responsiveness, as well as for radiometric detection of bacterial growth in various gaseous atmospheres

Dissolution and particle size characterization of radioactive contaminants in Hanford facilities: Criteria for methods of measurement

International Nuclear Information System (INIS)

Briant, J.K.; James, A.C.

1990-08-01

The purpose of this document is to discuss experimental methods that can be applied to evaluate the rate at which an actinide material is likely to dissolve in biological fluids. Criteria are recommended for the design and conduct of meaningful experimental procedures to sample a representative size fraction of the source material, to measure the rate of radionuclide dissolution, and to apply the results to assign the material to an appropriate ICRP Publication-30 lung retention class (or mixture of classes). 26 refs., 3 figs., 3 tabs

Enhancement of solubility and dissolution rate of atorvastatin ...

African Journals Online (AJOL)

Purpose: To investigate the formation of atorvastatin calcium (AC) co-crystal to improve its solubility and dissolution rate. Method: Co-crystallization of AC in equimolar ratio with isonicotinamide (INA) was carried out by slow solvent evaporation method using methanol. The solid obtained was characterized by powder x-ray ...

The use of commercial microwave dissolution equipment for the fast and reliable dissolution of high-fired POX and MOX samples

International Nuclear Information System (INIS)

Tushingham, J.; McInnes, C.; Firkin, S.

1998-09-01

The use of commercially available microwave dissolution equipment for the fast and reliable dissolution of high-fired plutonium dioxide (POX) and mixed oxide (MOX) samples has been evaluated for application to Safeguards Analysis. Under the auspices of the UK R and D Support Programme to the IAEA, equipment has been purchased and tested for the high-pressure microwave dissolution of POX samples fired to 1250 deg. C and MOX samples fired to 1600 deg. C, in concentrated nitric acid and hydrofluoric acid mixture. Considerable problems were encountered during development of procedures for microwave dissolution, resulting largely from sudden changes in pressure within dissolution vessels, which resulted in actuation of safety interlocks designed to prevent overpressurisation. These difficulties were alleviated by controlling the microwave power to reduce the reaction temperature and pressure, and also by introducing additional safety valves into the digestion vessels. Using microwave digestion, dissolution times for high fired POX and MOX samples were substantially reduced. Samples which required ca. 10 hours to dissolve by conventional means could be dissolved in ca. 80 minutes by microwave digestion. Whilst a similar performance in terms of plutonium recovery was achieved for some materials by microwave and conventional dissolution, for other materials microwave dissolution gave higher plutonium recoveries but with poorer precision. This suggests the possible presence of some plutonium oxide within high-fired materials which is more difficult to dissolve than the bulk, and which is perhaps dissolved to an additional but variable degree by the current microwave dissolution procedure. Microwave dissolution has been demonstrated to increase the speed of dissolution of high-fired POX and MOX materials, compared with conventional dissolution. However, the technique has not yet proved satisfactory for the complete dissolution of all high-fired materials tested because of

Double-label immunofluorescence method for simultaneous detection of adenovirus and herpes simplex virus from the eye.

Science.gov (United States)

Walpita, P; Darougar, S

1989-07-01

The development and application of a double-label immunofluorescence method which has the potential to screen for single or dual infections from any site, in single shell vial cultures, is described. In this study, a total of 1,141 ocular specimens were inoculated in shell vials, centrifuged at 15,000 X g for 1 h, incubated at 37 degrees C for 48 h, and fixed in methanol at room temperature for 15 min. The virus inclusions were detected by staining with a double-label indirect immunofluorescence procedure using mixtures of appropriate first antibodies, followed by fluorescein- and rhodamine-conjugated second antibodies. Each specimen was also inoculated in parallel by the conventional virus isolation method. The sensitivity and specificity of the double-label shell vial procedure were comparable to those with the conventional method, and the former test took only 48 h to complete. The test offers a rapid and simple single-vial procedure which allows for individual or simultaneous detection of multiple pathogens. It results in savings in time and cost over the conventional virus isolation method and other shell vial procedures.

Mechanistic Basis of Cocrystal Dissolution Advantage.

Science.gov (United States)

Cao, Fengjuan; Amidon, Gordon L; Rodríguez-Hornedo, Naír; Amidon, Gregory E

2018-01-01

Current interest in cocrystal development resides in the advantages that the cocrystal may have in solubility and dissolution compared with the parent drug. This work provides a mechanistic analysis and comparison of the dissolution behavior of carbamazepine (CBZ) and its 2 cocrystals, carbamazepine-saccharin (CBZ-SAC) and carbamazepine-salicylic acid (CBZ-SLC) under the influence of pH and micellar solubilization. A simple mathematical equation is derived based on the mass transport analyses to describe the dissolution advantage of cocrystals. The dissolution advantage is the ratio of the cocrystal flux to drug flux and is defined as the solubility advantage (cocrystal to drug solubility ratio) times the diffusivity advantage (cocrystal to drug diffusivity ratio). In this work, the effective diffusivity of CBZ in the presence of surfactant was determined to be different and less than those of the cocrystals. The higher effective diffusivity of drug from the dissolved cocrystals, the diffusivity advantage, can impart a dissolution advantage to cocrystals with lower solubility than the parent drug while still maintaining thermodynamic stability. Dissolution conditions where cocrystals can display both thermodynamic stability and a dissolution advantage can be obtained from the mass transport models, and this information is useful for both cocrystal selection and formulation development. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Experimental hydrothermal dissolution of forsterite, enstatite, diopside, and labradorite

Energy Technology Data Exchange (ETDEWEB)

Ponader, H.B.

1989-01-01

Natural hydrothermal water/rock interactions such as those which occur during mineral dissolution and serpentinization were experimentally duplicated using a flow-through apparatus. Labradorite, forsterite, enstatite, diopside, and lherzolite powders were reached with flowing aqueous fluids ({approximately} 10 ml/day) at 300 C and 300 bars for up to 58 days in order to quantify mineral stabilities and dissolution rates, and to characterize dissolution textures and mechanisms. The principal methods for characterization of the solids included surface sensitive spectroscopies (SAM and SPS), SEM, and XRD; reacted fluids were analyzed for major element chemistry and pH. Chapters 1 and 2 investigate labradorite dissolution by deionized water. The labradorite powder dissolved extensively while boehmite and halloysite precipitated. The SAM results show that, in general, the reacted surfaces are enriched in Al and depleted in Si, Na, and Ca. Chapter 3 describes the experiments that reacted deionized water with diopside, enstatite, forsterite, and lherzolite, from which lizardite {plus minus} chrysotile {plus minus} Fe-oxides precipitated. The reacted diopside and enstatite surfaces appeared highly corroded; their crystal structures, in part, control the mechanisms by which they dissolve. The stabilities of the minerals decrease in the order: lherzolite > diopside > enstatite > forsterite. At near neutral pH, the degree to which total surface areas influence dissolution rates appears greater that the effect of mineral composition and interaction of the primary minerals within the lherzolite.

Streamlined sample cleanup using combined dispersive solid-phase extraction and in-vial filtration for analysis of pesticides and environmental pollutants in shrimp

Energy Technology Data Exchange (ETDEWEB)

Han, Lijun [College of Science, China Agricultural University, Beijing (China); Sapozhnikova, Yelena [U.S. Dept. of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038 (United States); Lehotay, Steven J., E-mail: Steven.Lehotay@ars.usda.gov [U.S. Dept. of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038 (United States)

2014-05-01

Highlights: • The first report that combines in-vial filtration and dispersive-SPE for sample cleanup. • The unique application of ammonium formate for salting-out partitioning in QuEChERS. • Evaluations of a new zirconium-based and a non-friable GCB sorbent for d-SPE cleanup. • A new analytical method for 59 pesticides and environmental pollutants in shrimp. Abstract: A new method of sample preparation was developed and is reported for the first time. The approach combines in-vial filtration with dispersive solid-phase extraction (d-SPE) in a fast and convenient cleanup of QuEChERS (quick, easy, cheap, effective, rugged, and safe) extracts. The method was applied to simultaneous analysis of 42 diverse pesticides and 17 environmental contaminants, including polycyclic aromatic hydrocarbons, polychlorinated biphenyls (PCBs), and flame retardants, in shrimp as the sample matrix. Final extracts were analyzed by both low-pressure gas chromatography – triple quadrupole tandem mass spectrometry (LPGC-MS/MS), and high-performance liquid chromatography – triple quadrupole tandem mass spectrometry (HPLC-MS/MS) to provide a wide scope of analysis for targeted analytes. During method development, several different commercial sorbents for d-SPE were investigated and compared with respect to analyte recoveries. The method was validated at 10, 50, and 100 ng g⁻¹ spiking levels (10-fold lower for PCBs), and the results for nearly all analytes were between 70 and 115% recoveries with ≤17% relative standard deviations. The method was shown to be simple, fast, and effective for multi-application analysis of chemical residues in the representative food and environmental marker matrix.

Synthesis and dissolution studies of nickel ferrite in PDCA based formulations

International Nuclear Information System (INIS)

Ranganathan, S.; Raghavan, P.S.; Gopalan, R.; Srinivasan, M.P.; Narasimhan, S.V.

2000-01-01

Nickel ferrite is one of the important corrosion product in the pipeline surfaces of water cooled nuclear reactors. The dissolution of the nickel ferrite by chelating agents is very sensitive to nature of the chelant, nature of the reductant used in the formulation and the temperature at which the dissolution studies have been performed. The dissolution is dominated by the adsorption of the complexing agent at the oxide surface, but mainly controlled by the reductive dissolution of the ferrite particles. This is due to the in situ release of Fe 2+ ions or the generation of Fe 2+ ions by the reduction of Fe 3+ ions by the reductants in the solution. This study deals with the leaching of iron and nickel from nickel ferrite prepared by the solid state method. The prepared nickel ferrite samples are characterised by XRD to confirm the ferrite formation. The dissolution studies are performed in PDCA formulations containing organic reductants like ascorbic acid and LOMI reductants like Fe(II)-PDCA. The dissolution rate of nickel ferrite at 85degC increased with the increase of Fe 2+ ion content in the crystal lattice. Fe(II)-PDCA was found to be better reductants in dissolving the nickel ferrite in comparison with ascorbic acid. (author)

Accelerated dissolution of iron oxides in ice

Directory of Open Access Journals (Sweden)

D. Jeong

2012-11-01

Full Text Available Iron dissolution from mineral dusts and soil particles is vital as a source of bioavailable iron in various environmental media. In this work, the dissolution of iron oxide particles trapped in ice was investigated as a new pathway of iron supply. The dissolution experiments were carried out in the absence and presence of various organic complexing ligands under dark condition. In acidic pH conditions (pH 2, 3, and 4, the dissolution of iron oxides was greatly enhanced in the ice phase compared to that in water. The dissolved iron was mainly in the ferric form, which indicates that the dissolution is not a reductive process. The extent of dissolved iron was greatly affected by the kind of organic complexing ligands and the surface area of iron oxides. The iron dissolution was most pronounced with high surface area iron oxides and in the presence of strong iron binding ligands. The enhanced dissolution of iron oxides in ice is mainly ascribed to the "freeze concentration effect", which concentrates iron oxide particles, organic ligands, and protons in the liquid like ice grain boundary region and accelerates the dissolution of iron oxides. The ice-enhanced dissolution effect gradually decreased when decreasing the freezing temperature from −10 to −196 °C, which implies that the presence and formation of the liquid-like ice grain boundary region play a critical role. The proposed phenomenon of enhanced dissolution of iron oxides in ice may provide a new pathway of bioavailable iron production. The frozen atmospheric ice with iron-containing dust particles in the upper atmosphere thaws upon descending and may provide bioavailable iron upon deposition onto the ocean surface.

In vitro dissolution methodology, mini-Gastrointestinal Simulator (mGIS), predicts better in vivo dissolution of a weak base drug, dasatinib.

Science.gov (United States)

Tsume, Yasuhiro; Takeuchi, Susumu; Matsui, Kazuki; Amidon, Gregory E; Amidon, Gordon L

2015-08-30

USP apparatus I and II are gold standard methodologies for determining the in vitro dissolution profiles of test drugs. However, it is difficult to use in vitro dissolution results to predict in vivo dissolution, particularly the pH-dependent solubility of weak acid and base drugs, because the USP apparatus contains one vessel with a fixed pH for the test drug, limiting insight into in vivo drug dissolution of weak acid and weak base drugs. This discrepancy underscores the need to develop new in vitro dissolution methodology that better predicts in vivo response to assure the therapeutic efficacy and safety of oral drug products. Thus, the development of the in vivo predictive dissolution (IPD) methodology is necessitated. The major goals of in vitro dissolution are to ensure the performance of oral drug products and the support of drug formulation design, including bioequivalence (BE). Orally administered anticancer drugs, such as dasatinib and erlotinib (tyrosine kinase inhibitors), are used to treat various types of cancer. These drugs are weak bases that exhibit pH-dependent and high solubility in the acidic stomach and low solubility in the small intestine (>pH 6.0). Therefore, these drugs supersaturate and/or precipitate when they move from the stomach to the small intestine. Also of importance, gastric acidity for cancer patients may be altered with aging (reduction of gastric fluid secretion) and/or co-administration of acid-reducing agents. These may result in changes to the dissolution profiles of weak base and the reduction of drug absorption and efficacy. In vitro dissolution methodologies that assess the impact of these physiological changes in the GI condition are expected to better predict in vivo dissolution of oral medications for patients and, hence, better assess efficacy, toxicity and safety concerns. The objective of this present study is to determine the initial conditions for a mini-Gastrointestinal Simulator (mGIS) to assess in vivo

[Effect of stability and dissolution of realgar nano-particles using solid dispersion technology].

Science.gov (United States)

Guo, Teng; Shi, Feng; Yang, Gang; Feng, Nian-Ping

2013-09-01

To improve the stability and dissolution of realgar nano-particles by solid dispersion. Using polyethylene glycol 6000 and poloxamer-188 as carriers, the solid dispersions were prepare by melting method. XRD, microscopic inspection were used to determine the status of realgar nano-particles in solid dispersions. The content and stability test of As(2)0(3) were determined by DDC-Ag method. Hydride generation atomic absorption spectrometry was used to determine the content of Arsenic and investigated the in vitro dissolution behavior of solid dispersions. The results of XRD and microscopic inspection showed that realgar nano-particles in solid dispersions were amorphous. The dissolution amount and rate of Arsenic from realgar nano-particles of all solid dispersions were increased significantly, the reunion of realgar nano-particles and content of As(2)0(3) were reduced for the formation of solid dispersions. The solid dispersion of realgar nano-particles with poloxamer-188 as carriers could obviously improve stability, dissolution and solubility.

Dissolution comparisons using a Multivariate Statistical Distance (MSD) test and a comparison of various approaches for calculating the measurements of dissolution profile comparison.

Science.gov (United States)

Cardot, J-M; Roudier, B; Schütz, H

2017-07-01

The f 2 test is generally used for comparing dissolution profiles. In cases of high variability, the f 2 test is not applicable, and the Multivariate Statistical Distance (MSD) test is frequently proposed as an alternative by the FDA and EMA. The guidelines provide only general recommendations. MSD tests can be performed either on raw data with or without time as a variable or on parameters of models. In addition, data can be limited-as in the case of the f 2 test-to dissolutions of up to 85% or to all available data. In the context of the present paper, the recommended calculation included all raw dissolution data up to the first point greater than 85% as a variable-without the various times as parameters. The proposed MSD overcomes several drawbacks found in other methods.

Do insulin cartridges really provide a lower risk of potential diabetes complications than traditional vials?

Science.gov (United States)

Al-Sharayri, Mohammad G; Aljbori, Tariq M; Migdadi, Qusai M; Al-Omoush, Marwa B; Jaarah, Ayman R

2014-09-01

Recently, many publicly funded healthcare organizations suffered from an economical crisis. This forced some organizations to utilize less costly alternatives where possible. Insulin cartridges and vials are examples. Many patients are questioning the difference between the two alternatives as they contain the same active ingredient. To find out if insulin cartridges really provide a lower risk of potential diabetes complications than traditional vials. A questionnaire was used to ask two random samples of diabetic patients about the development of some diabetes complications. The first sample (n = 41) consisted of patients using cartridges; the second sample (n = 40) consisted of patients using vials. Patients were randomly selected from the endocrine clinic and the out-patient pharmacy in Al-Hussein Hospital in King Hussein Medical Center in Amman- Jordan. 44% of respondents in the first sample did not suffer from any complication; on the other hand, the percentage was only 15% of respondents in the second sample. All respondents (100%) in the first sample suffered from only 2 complications or less; however, 25% of the respondents in the second sample suffered from 3 or more complications. Nephropathy complications, were slightly higher in the first sample; 22% compared to 15% in the second sample. On the other hand, all complications reported in the second sample were higher; 30% for neuropathy, 65% for retinopathy complications and 42.5% for extremities damage compared to only 9.7%, 7.3% and 26.8% respectively in the first sample. In general, respondents who were using cartridges reported a lesser incidence of diabetes complications. Although many organizations suffered from an economical crisis, the cost-effectiveness aspect should be taken into consideration when purchasing medical alternatives. This will provide higher quality of life for patients and eventually lower hidden and future costs for the organizations.

Comparative analysis of ampoules and vials in sterile and conventional packaging as to microbial load and sterility test.

Science.gov (United States)

Freitas, Raphael Ribeiro de Aquino; Tardelli, Maria Angela

2016-05-24

To compare sterility and microbial (bacteria and fungi) load in the outer part of hyperbaric bupivacaine (Neocaína®) in ampoule and bupivacaine in vial, in conventional and sterile pack formulations. The sterile packs were divided into two groups: G1 (n=16) with ampoules and G2 (n=16) with vials. Conventional formulations were divided into two groups, being G3 (n=16) with ampoules and G4 (n=16) with vials. The ampoules and vials were opened and had their content drawn. The empty bottles were then placed in sterile plastic bags and sent for analysis of microbial load (bacteria and fungi) and sterility testing. Data were analyzed using the χ2 test with Yates correction, and 95% confidence interval. G1 and G2 showed no bacterial growth when compared to conventional groups (pgrupos, sendo que o G1 (n=16) continha as ampolas e o G2 (n=16), os frascos-ampola. As apresentações convencionais foram distribuídas em dois grupos, a saber G3 (n=16) com as ampolas e G4 (n=16) com os frascos-ampola. As ampolas e os frascos-ampolas eram abertos e tinham seu conteúdo aspirado. Os frascos vazios eram, então, acondicionados em sacos plásticos estéreis e enviados para análise quanto à carga microbiana (bactérias e fungos), bem como para o teste de esterilidade. Os dados foram analisados por meio do teste χ2 com correção Yates com intervalo de confiança de 95%. Os grupos G1 e G2 não apresentaram crescimento bacteriano quando comparado aos grupos convencionais (pgrupos. O uso de embalagens estéreis (sterile pack) diminui a carga microbiana dos frascos de envasamentos, o que diminuiria a chance de exposição a uma potencial contaminação da solução anestésica.

The dissolution behavior of borosilicate glasses in far-from equilibrium conditions

Science.gov (United States)

Neeway, James J.; Rieke, Peter C.; Parruzot, Benjamin P.; Ryan, Joseph V.; Asmussen, R. Matthew

2018-04-01

An area of agreement in the waste glass corrosion community is that, at far-from-equilibrium conditions, the dissolution of borosilicate glasses used to immobilize nuclear waste is known to be a function of both temperature and pH. The aim of this work is to study the effects of temperature and pH on the dissolution rate of three model nuclear waste glasses (SON68, ISG, AFCI). The dissolution rate data are then used to parameterize a kinetic rate model based on Transition State Theory that has been developed to model glass corrosion behavior in dilute conditions. To do this, experiments were conducted at temperatures of 23, 40, 70, and 90 °C and pH (22 °C) values of 9, 10, 11, and 12 with the single-pass flow-through (SPFT) test method. Both the absolute dissolution rates and the rate model parameters are compared with previous results. Rate model parameters for the three glasses studied here are nearly equivalent within error and in relative agreement with previous studies though quantifiable differences exist. The glass dissolution rates were analyzed with a linear multivariate regression (LMR) and a nonlinear multivariate regression performed with the use of the Glass Corrosion Modeling Tool (GCMT), with which a robust uncertainty analysis is performed. This robust analysis highlights the high degree of correlation of various parameters in the kinetic rate model. As more data are obtained on borosilicate glasses with varying compositions, a mathematical description of the effect of glass composition on the rate parameter values should be possible. This would allow for the possibility of calculating the forward dissolution rate of glass based solely on composition. In addition, the method of determination of parameter uncertainty and correlation provides a framework for other rate models that describe the dissolution rates of other amorphous and crystalline materials in a wide range of chemical conditions. The higher level of uncertainty analysis would provide

Dissolution of Metal Supported Spent Auto Catalysts in Acids

Directory of Open Access Journals (Sweden)

Fornalczyk A.

2016-03-01

Full Text Available Metal supported auto catalysts, have been used in sports and racing cars initially, but nowadays their application systematically increases. In Metal Substrate (supported Converters (MSC, catalytic functions are performed by the Platinum Group Metals (PGM: Pt, Pd, Rh, similarly to the catalysts on ceramic carriers. The contents of these metals make that spent catalytic converters are valuable source of precious metals. All over the world there are many methods for the metals recovery from the ceramic carriers, however, the issue of platinum recovery from metal supported catalysts has not been studied sufficiently yet. The paper presents preliminary results of dissolution of spent automotive catalyst on a metal carrier by means of acids: H2SO4, HCl, HNO3, H3PO4. The main assumption of the research was the dissolution of base metals (Fe, Cr, Al from metallic carrier of catalyst, avoiding dissolution of PGMs. Dissolution was the most effective when concentrated hydrochloric acid, and 2M sulfuric acid (VI was used. It was observed that the dust, remaining after leaching, contained platinum in the level of 0.8% and 0.7%, respectively.

Safety and efficacy of multiuse botulinum toxin vials for intralaryngeal injection.

Science.gov (United States)

Barrow, Emily M; Rosen, Clark A; Hapner, Edie R; Smith, Sarah; Hatcher, Jeanne L; Simpson, Blake; Johns, Michael M

2015-05-01

Centers for Disease Control and Prevention guidelines maintain that single-use vials cannot be used for multiple patients. Botox product labeling states that the reconstituted toxin should be used within 4 hours on a single patient based on concerns of reduced potency, contamination, and consequent infections. The purpose of this study was to determine the safety and efficacy of using single-use vials in a multidose fashion. Prospective study and cohort chart review. A multi-institutional three-part study was performed between May 2013 and October 2013: 1) a summation of subjects' recall of their past experiences (symptoms/response) with previous multidose Botox injections, 2) a prospective study of intralaryngeal injections, and 3) a chart review of injection responses in a subset of the cohort. Seven hundred forty-three subjects receiving 6,216 injections demonstrated zero infection-related complications on retrospective chart review. One hundred seventy-nine subjects recalled 24.0% overall adverse events, 10.6% redness, 7.3% pain and swelling at the injection site, and 0% fever. One hundred seventy-four subjects prospectively reported 12.6% overall adverse events. The self-reported efficacy rate of Botox injection was 96.6%. The low rates of adverse events following the use of Botox in a multipatient fashion are consistent with other percutaneous injections. No evidence of infection was found with multidose Botox use. Given the low incidence of side effects and high success rate, Botox can be used both safely and effectively in a multipatient fashion. 4 © 2014 The American Laryngological, Rhinological and Otological Society, Inc.

Modelo y simulación de una intersección vial usando el software Arena

Directory of Open Access Journals (Sweden)

Sebastian Puerto Hernández

2015-06-01

Full Text Available En este artículo se presenta el modelo y la simulación de una intersección vial. Para modelar las dinámicas fue seleccionado el software Arena®, por su gran versatilidad y amplitud en herramientas a la hora de diseñar y modelar sistemas estocásticos. Las simulaciones en eventos discretos de la intersección validarán el modelo. Con el modelo obtenido se podrá realizar el cambio en la programación de los semáforos, la inclusión de paraderos en sitios específicos de las vías, y además la demostración de la relación entre la forma de conducción y estos problemas de movilidad. Se busca disminuir el tamaño de las colas que se generan, además de una reducción en los tiempos de recorridos de los usuarios en estos tramos y un mejoramiento notable en el funcionamiento vial en general de la ciudad.

Dissolution and Quantification of Tantalum-Containing Compounds ...

African Journals Online (AJOL)

NICO

2The South African Nuclear Energy Corporation Ltd. (Necsa), P.O. Box 582, Pretoria 0001, South Africa. Received 30 ... The success of the different dissolution methods was evaluated on percentage .... Other validation parameters9,10 such as accuracy, precision, ..... pled Plasma-Atomic Emission Spectroscopy. An Atlas of ...

Improvement of database on glass dissolution

International Nuclear Information System (INIS)

Hayashi, Maki; Sasamoto, Hiroshi; Yoshikawa, Hideki

2008-03-01

In geological disposal system, high-level radioactive waste (HLW) glass is expected to retain radionuclide for the long term as the first barrier to prevent radionuclide release. The advancement of its performance assessment technology leads to the reliability improvement of the safety assessment of entire geological disposal system. For this purpose, phenomenological studies for improvement of scientific understanding of dissolution/alteration mechanisms, and development of robust dissolution/alteration model based on the study outcomes are indispensable. The database on glass dissolution has been developed for supporting these studies. This report describes improvement of the prototype glass database. Also, this report gives an example of the application of the database for reliability assessment of glass dissolution model. (author)

In Vitro-In Vivo Predictive Dissolution-Permeation-Absorption Dynamics of Highly Permeable Drug Extended-Release Tablets via Drug Dissolution/Absorption Simulating System and pH Alteration.

Science.gov (United States)

Li, Zi-Qiang; Tian, Shuang; Gu, Hui; Wu, Zeng-Guang; Nyagblordzro, Makafui; Feng, Guo; He, Xin

2018-05-01

Each of dissolution and permeation may be a rate-limiting factor in the absorption of oral drug delivery. But the current dissolution test rarely took into consideration of the permeation property. Drug dissolution/absorption simulating system (DDASS) valuably gave an insight into the combination of drug dissolution and permeation processes happening in human gastrointestinal tract. The simulated gastric/intestinal fluid of DDASS was improved in this study to realize the influence of dynamic pH change on the complete oral dosage form. To assess the effectiveness of DDASS, six high-permeability drugs were chosen as model drugs, including theophylline (pK a1  = 3.50, pK a2  = 8.60), diclofenac (pK a  = 4.15), isosorbide 5-mononitrate (pK a  = 7.00), sinomenine (pK a  = 7.98), alfuzosin (pK a  = 8.13), and metoprolol (pK a  = 9.70). A general elution and permeation relationship of their commercially available extended-release tablets was assessed as well as the relationship between the cumulative permeation and the apparent permeability. The correlations between DDASS elution and USP apparatus 2 (USP2) dissolution and also between DDASS permeation and beagle dog absorption were developed to estimate the predictability of DDASS. As a result, the common elution-dissolution relationship was established regardless of some variance in the characteristic behavior between DDASS and USP2 for drugs dependent on the pH for dissolution. Level A in vitro-in vivo correlation between DDASS permeation and dog absorption was developed for drugs with different pKa. The improved DDASS will be a promising tool to provide a screening method on the predictive dissolution-permeation-absorption dynamics of solid drug dosage forms in the early-phase formulation development.

Formation, transformation and dissolution of phases formed on surfaces

International Nuclear Information System (INIS)

Shoesmith, D.W.

1983-03-01

The basic mechanisms of film growth, transformation, and dissolution of phases formed on surfaces are discussed. Film growth can occur via solid-state processes or via substrate (usally metal or alloy) dissolution, followed by local supersaturation and precipitation of an insoluble phase. The phase(s) formed may be metastable and transform to a more stable phase, via either solid-state or dissolution-reprecipitation processes. Film dissolution reactions can also occur via a variety of mechanisms, including: (i) direct chemical dissolution when no oxidation state change occurs; (ii) redox dissolution when the film dissolves via a redox reaction involving a reducing or oxidizing agent in solution; and (iii) autoreduction, where film dissolution is coupled to metal dissolution. Such film-growth and dissolution processes, which often produce complex multilayer films, are common in the nuclear industry. A number of examples are discussed

Dissolution of UO2 in redox conditions

International Nuclear Information System (INIS)

Casas, I.; Pablo de, J.; Rovira, M.

1998-01-01

The performance assessment of the final disposal of the spent nuclear fuel in geological formations is strongly dependent on the spent fuel matrix dissolution. Unirradiated uranium (IV) dioxide has shown to be very useful for such purposes. The stability of UO 2 is very dependent on vault redox conditions. At reducing conditions, which are expected in deep groundwaters, the dissolution of the UO 2 -matrix can be explained in terms of solubility, while under oxidizing conditions, the UO 2 is thermodynamically unstable and the dissolution is kinetically controlled. In this report the parameters which affect the uranium solubility under reducing conditions, basically pH and redox potential are discussed. Under oxidizing conditions, UO 2 dissolution rate equations as a function of pH, carbonate concentration and oxidant concentration are reported. Dissolution experiments performed with spent fuel are also reviewed. The experimental equations presented in this work, have been used to model independent dissolution experiments performed with both unirradiated and irradiated UO 2 . (Author)

False-positive cryptococcal antigen test associated with use of BBL Port-a-Cul transport vials.

Science.gov (United States)

Wilson, Deborah A; Sholtis, Mary; Parshall, Sharon; Hall, Gerri S; Procop, Gary W

2011-02-01

A total of 52 residual CSF and serum specimens, which were originally negative with the Cryptococcal Antigen Latex Agglutination System (CALAS), were shown to become falsely positive after placement in BBL Port-A-Cul anaerobic transport vials. This transport device, although excellent for specimen transportation for subsequent culture, should not be used if cryptococcal antigen testing is needed.

Componentes descriptivos y explicativos de la accidentalidad vial en Colombia: Incidencia del factor humano

Directory of Open Access Journals (Sweden)

Ervyn H. Norza Céspedes

2016-03-01

Full Text Available Problema: Se analizó la incidencia del factor humano en la accidentalidad vial en el territorio colombiano, y se identificó evidencia empírica para la formulación de política pública del tránsito. Metodología: El diseño es descriptivo-correlacional. Instrumentos: cuestionario de comportamiento para conductores y motociclistas (D.B.Q. y encuesta tipo Likert. Muestra no probabilística intencional: 16.322 personas (8.631 conductores de automotores, 5.133 motociclistas y 2.558 peatones, pasajeros y acompañantes. Resultados: a conductores con nivel educativo superior inciden en menos accidentes; b peatones con menor nivel educativo inciden en mayores conductas riesgosas; c las mujeres tienen actitud positiva y perciben eficacia de campañas en prevencion; d estilos de conducción iracundo, ansioso, riesgoso y de alta velocidad cometen más infracciones y accidentes; e desobedecer señales de tránsito, la principal causa de accidentalidad; f agresividad, hostilidad y estrés en el tránsito son factores que aumentan la probabilidad de accidente; g campañas de prevención no están siendo captadas por la población más afectada. Conclusiones y recomendaciones: Los factores de accidentalidad vial guardan correspondencia con el Triángulo de Seguridad Vial establecido por la Organización de las Naciones Unidas -factor humano preponderante en la accidentalidad-. Lineamientos de política pública fundamentados en procesos educativos y corporativos tendientes a disminuir la accidentalidad por lo general no se concibe aplicada a la seguridad pública. Por ello, se presenta la inteligencia criminal como una disciplina que se ocupa de anticipar los riesgos criminales contra la seguridad pública. Esto permitiría disminuir la incertidumbre durante la toma de decisiones y calcular los daños contra la seguridad pública, que se pretende prevenir.

Unravelling the relationship between degree of disorder and the dissolution behavior of milled glibenclamide

DEFF Research Database (Denmark)

Mah, Pei T; Laaksonen, Timo; Rades, Thomas

2014-01-01

Milling is an attractive method to prepare amorphous formulations as it does not require the use of solvents and is suitable for thermolabile drugs. One of the key critical quality attributes of milled amorphous formulations is their dissolution behavior. However, there are limited studies...... that have investigated the relationship between degree of disorder induced by milling and dissolution behavior. The main aim of this study was to identify the analytical technique used to characterize degree of disorder that correlates best with the recrystallization behavior during dissolution of milled...... glibenclamide samples. Solid state and surface changes during dissolution of milled glibenclamide samples were monitored in order to elucidate the processes that influence the dissolution behavior of milled glibenclamide samples. Glibenclamide was ball milled for different durations and analyzed using X...

Enhancement of solubility and dissolution rate of atorvastatin ...

African Journals Online (AJOL)

solvent evaporation method using methanol. ... crystal significantly increases in solubility with a dissolution rate 2 - 3 times faster than that of ... considered one of the most effective synthetic .... temperature of 37 ± 0.5 °C. The test was carried.

Transfer of drug dissolution testing by statistical approaches: Case study

Science.gov (United States)

AL-Kamarany, Mohammed Amood; EL Karbane, Miloud; Ridouan, Khadija; Alanazi, Fars K.; Hubert, Philippe; Cherrah, Yahia; Bouklouze, Abdelaziz

2011-01-01

The analytical transfer is a complete process that consists in transferring an analytical procedure from a sending laboratory to a receiving laboratory. After having experimentally demonstrated that also masters the procedure in order to avoid problems in the future. Method of transfers is now commonplace during the life cycle of analytical method in the pharmaceutical industry. No official guideline exists for a transfer methodology in pharmaceutical analysis and the regulatory word of transfer is more ambiguous than for validation. Therefore, in this study, Gauge repeatability and reproducibility (R&R) studies associated with other multivariate statistics appropriates were successfully applied for the transfer of the dissolution test of diclofenac sodium as a case study from a sending laboratory A (accredited laboratory) to a receiving laboratory B. The HPLC method for the determination of the percent release of diclofenac sodium in solid pharmaceutical forms (one is the discovered product and another generic) was validated using accuracy profile (total error) in the sender laboratory A. The results showed that the receiver laboratory B masters the test dissolution process, using the same HPLC analytical procedure developed in laboratory A. In conclusion, if the sender used the total error to validate its analytical method, dissolution test can be successfully transferred without mastering the analytical method validation by receiving laboratory B and the pharmaceutical analysis method state should be maintained to ensure the same reliable results in the receiving laboratory. PMID:24109204

Kinetics of oxidic phase dissolution in acids

International Nuclear Information System (INIS)

Gorichev, I.G.; Kipriyanov, N.A.

1981-01-01

The critical analysis of the experimental data on dissolution kinetics of metal oxides (BeO, V 2 O 5 , UO 2 , Nb 2 O 5 , Ta 2 O 5 etc.) in acid media is carried out. Kinetic peculiarities of oxide dissolution are explained on the basis of the notions of electron- proton theory. It is established that the surface nonstoichiometric ccomposition of oxide phase and potential jump, appearing on the interface of the oxide-electrolyte phase are the important factors, determining the dissolution rate of a solid phase. The dissolution rate of metal oxides is limited by the transition of protons into the solid oxide phase. Morphological models of heterogeneous kinetics are used when explaining kinetic regularities of oxide dissolution process [ru

Chemistry of proposed calcination/dissolution processing of Hanford Site tank wastes

International Nuclear Information System (INIS)

Delegard, C.H.

1995-01-01

Plans exist to separate radioactive waste stored in underground tanks at the US Department of Energy's Hanford Site in south central Washington State into low-level and high-level fractions, and to immobilize the separate fractions in high-integrity vitrified forms for long-term disposal. Calcination with water dissolution has been proposed as a possible treatment for achieving low/high-level separation. Chemistry development activities conducted since 1992 with simulated and genuine tank waste show that calcination/dissolution destroys organic carbon and converts nitrate and nitrite to hydroxide and benign offgases. The process also dissolves significant quantities of bulk chemicals (aluminum, chromium, and phosphate), allowing their redistribution from the high-level to the low-level fraction. Present studies of the chemistry of calcination/dissolution processing of genuine wastes, conducted in the period October 1993 to September 1994, show the importance of sodium fluoride phosphate double salt in controlling phosphate dissolution. Peptization of waste solids is of concern if extensive washing occurs. Strongly oxidizing conditions imposed by calcination reactions were found to convert transition metals to soluble anions in the order chromate > manganate > > ferrate. In analogy with manganese behavior, plutonium dissolution, presumably by oxidation to more soluble anionic species, also occurs by calcination/dissolution. Methods to remove plutonium from the product low-level solution stream must be developed

Dissolution rate of BTEX contaminants in water

International Nuclear Information System (INIS)

Njobuenwu, D.O.; Amadi, S.A.; Ukpaka, P.C.

2005-01-01

Benzene, toluene, ethylbenzene and xylenes (BTEX) and substituted benzenes are the most common aromatic compounds in petroleum. BTEX components are the most soluble and mobile fraction of crude oil and many petroleum products, and frequently enter soil, sediments and aquatic environments because of accidental spills, leaks and improper oil waste disposal practices. The mass transfer process of hydrocarbons in aquatic mediums has received considerable attention in the literature. This paper focused on the molecular mass transfer rate of BTEX in water, with the aim of understanding and predicting contaminant fate and transport. A comprehensive model was developed to simulate the molecular dissolution rate of BTEX in a natural water stream. The model considered the physicochemical properties of the BTEX compounds and physical processes relevant to the spreading of contaminants in the sea. The dissolution rate was a function of oil slick area, dissolution mass transferability and oil solubility in water. The total dissolution rate N was calculated and the dissolution mass transfer coefficient K was given as the point value of mass transfer coefficient. Results for the dissolution rate based on the solubility of the components in the water were compared with analytical solutions from previous studies and showed good agreement. The model showed that benzene had the largest dissolution rate, while o-xylene had the lowest rate because of its lower fraction. Benzene dissolution rate was approximately 2.6, which was 20.6 times that of toluene and ethylbenzene. It was concluded that the model is useful in predicting and monitoring the dissolution rate of BTEX contaminants in soil and water systems. 22 refs., 2 tabs., 3 figs

Formalization of the kinetics for autocatalytic dissolutions. Focus on the dissolution of uranium dioxide in nitric medium

International Nuclear Information System (INIS)

Charlier, F.; Canion, D.; Gravinese, A.; Magnaldo, A.; Lalleman, S.; Borda, G.; Schaer, E.

2017-01-01

Uranium dioxide dissolution in nitric acid is a complex reaction. On the one hand, the dissolution produces nitrous oxides (NOX), which makes it a triphasic reaction. On the other hand, one of the products accelerates the kinetic rate; the reaction is hence called autocatalytic.The kinetics for these kinds of reactions need to be formalized in order to optimize and design innovative dissolution reactors. In this work, the kinetics rates have been measured by optical microscopy using a single particle approach. The advantages of this analytical technique are an easier management of species transport in solution and a precise following of the dissolution rate. The global rate is well described by a mechanism considering two steps: a non-catalyzed reaction, where the catalyst concentration has no influence on the dissolution rate, and a catalyzed reaction. The mass transfer rate of the catalyst was quantified in order to discriminate when the reaction was influenced by catalyst accumulated in the boundary layer or uncatalyzed. This first approximation described well the sigmoid dissolution curve profile. Moreover, experiments showed that solutions filled with catalyst proved to lose reactivity over time. Results pointed out that the higher the liquid-gas exchanges, the faster the kinetic rate decreases with time. Thus, it was demonstrated, for the first time, that there is a link between catalyst and nitrous oxides. The outcome of this study leads to new ways for improving the design of dissolvers. Gas-liquid exchanges are indeed a lever to impact dissolution rates. Temperature and catalyst concentration can be optimized to reduce residence times in dissolvers. (authors)

Fracture Dissolution of Carbonate Rock: An Innovative Process for Gas Storage

Energy Technology Data Exchange (ETDEWEB)

James W. Castle; Ronald W. Falta; David Bruce; Larry Murdoch; Scott E. Brame; Donald Brooks

2006-10-31

The goal of the project is to develop and assess the feasibility and economic viability of an innovative concept that may lead to commercialization of new gas-storage capacity near major markets. The investigation involves a new approach to developing underground gas storage in carbonate rock, which is present near major markets in many areas of the United States. Because of the lack of conventional gas storage and the projected growth in demand for storage capacity, many of these areas are likely to experience shortfalls in gas deliverability. Since depleted gas reservoirs and salt formations are nearly non-existent in many areas, alternatives to conventional methods of gas storage are required. The need for improved methods of gas storage, particularly for ways to meet peak demand, is increasing. Gas-market conditions are driving the need for higher deliverability and more flexibility in injection/withdrawal cycling. In order to meet these needs, the project involves an innovative approach to developing underground storage capacity by creating caverns in carbonate rock formations by acid dissolution. The basic concept of the acid-dissolution method is to drill to depth, fracture the carbonate rock layer as needed, and then create a cavern using an aqueous acid to dissolve the carbonate rock. Assessing feasibility of the acid-dissolution method included a regional geologic investigation. Data were compiled and analyzed from carbonate formations in six states: Indiana, Ohio, Kentucky, West Virginia, Pennsylvania, and New York. To analyze the requirements for creating storage volume, the following aspects of the dissolution process were examined: weight and volume of rock to be dissolved; gas storage pressure, temperature, and volume at depth; rock solubility; and acid costs. Hydrochloric acid was determined to be the best acid to use because of low cost, high acid solubility, fast reaction rates with carbonate rock, and highly soluble products (calcium chloride

Dissolution Dynamic Nuclear Polarization capability study with fluid path

DEFF Research Database (Denmark)

Malinowski, Ronja Maja; Lipsø, Hans Kasper Wigh; Lerche, Mathilde Hauge

2016-01-01

Signal enhancement by hyperpolarization is a way of overcoming the low sensitivity in magnetic resonance; MRI in particular. One of the most well-known methods, dissolution Dynamic Nuclear Polarization, has been used clinically in cancer patients. One way of ensuring a low bioburden of the hyperp......Signal enhancement by hyperpolarization is a way of overcoming the low sensitivity in magnetic resonance; MRI in particular. One of the most well-known methods, dissolution Dynamic Nuclear Polarization, has been used clinically in cancer patients. One way of ensuring a low bioburden...... of the hyperpolarized product is by use of a closed fluid path that constitutes a barrier to contamination. The fluid path can be filled with the pharmaceuticals, i.e. imaging agent and solvents, in a clean room, and then stored or immediately used at the polarizer. In this study, we present a method of filling...

Calibration-free sensor for pressure and H2O concentration in headspace of sterile vial using tunable diode laser absorption spectroscopy.

Science.gov (United States)

Cai, Tingdong; Gao, Guangzhen; Liu, Ying

2013-11-10

Tunable diode laser absorption measurements of pressure and H2O concentration in the headspace of vials using a distributed-feedback (DFB) diode laser near 1.4 μm are reported. A H2O line located near 7161.41 cm(-1) is selected based on its strong absorption strength and isolation from interference of neighboring transitions. Direct absorption spectra of H2O are obtained for the measurement path as well as the reference path by scanning the laser wavelength. The pressure and H2O vapor concentration in the headspace of a vial are inferred from a differential absorption signal, which is the difference between the measured and the referenced absorbance spectra. This sensor is calibration-free and no purge gas is needed. The demonstrated capability would enable measurements of pressure and H2O concentration in the headspace of vials within 2.21% and 2.86%, respectively. A precision of 1.02 Torr and 390 ppm is found for the pressure and H2O concentration, respectively. A set of measurements for commercial freeze-dried products are also performed to illustrate the usefulness of this sensor.

Preparation of iron metal nano solution by anodic dissolution with high voltage

International Nuclear Information System (INIS)

Nguyen Duc Hung; Do Thanh Tuan

2012-01-01

Iron nano metal solution is prepared from anodic dissolution process with ultra- high Dc voltage. The size and shape of iron nanoparticles determined by Tem images and particle size distribution on the device LA-950 Laser Scattering Particle Distribution Analyzer V2. The concentration of nano-iron solution was determined by the analytical methods AAS atomic absorption spectrometry and Faraday's law. The difference in concentration of both methods demonstrated outside the anodic dissolution process has created the water electrolysis to form H 2 and O 2 gases and heating the solution. (author)

On-line monitoring of lithium carbonate dissolution

Energy Technology Data Exchange (ETDEWEB)

Sun, Yuzhu; Song, Xingfu; Wang, Jin; Luo, Yan; Yu, Jianguo [National Engineering Research Center for Integrated Utilization Salt Lake Resources, East China University of Science and Technology, Shanghai (China)

2009-11-15

Dissolution of lithium carbonate (Li{sub 2}CO{sub 3}) in aqueous solution was investigated using three on-line apparatuses: the concentration of Li{sub 2}CO{sub 3} was measured by electrical conductivity equipment; CLD (Chord Length Distribution) was monitored by FBRM (Focused Beam Reflectance Measurement); crystal image was observed by PVM (Particle Video Microscope). Results show dissolution rate goes up with a decrease of particle size, and with an increase in temperature; stirring speed causes little impact on dissolution; ultrasound facilitates dissolution obviously. The CLD evolution and crystal images of Li{sub 2}CO{sub 3}powders in stirred fluid were observed detailedly by FBRM and PVM during dissolution. Experimental data were fitted to Avrami model, through which the activation energy was found to be 34.35 kJ/mol. PBE (Population Balance Equation) and moment transform were introduced to calculate dissolution kinetics, obtaining correlation equations of particle size decreasing rate as a function of temperature and undersaturation. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Development and characterization of solid dispersion of piroxicam for improvement of dissolution rate using hydrophilic carriers

Directory of Open Access Journals (Sweden)

Mohammad Barzegar-jalali

2014-09-01

Full Text Available Introduction: The main objective of this study was preparation and characterization of solid dispersion of piroxicam to enhance its dissolution rate. Methods: Solid dispersion formulations with different carriers including crospovidone, microcrystalline cellulose and Elaeagnus angustifolia fruit powder and with different drug: carrier ratios were prepared employing cogrinding method. Dissolution study of the piroxicam powders, physical mixtures and solid dispersions was performed in simulated gastric fluid and simulated intestinal fluid using USP Apparatus type II. The physical characterization of formulations were analyzed using powder X ray diffraction (PXRD, particle size analyzer and differential scanning calorimetry (DSC. Interactions between the drug and carriers were evaluated by Fourier transform infrared (FT-IR spectroscopic method. Results: It was revealed that all of three carriers increase the dissolution rate of piroxicam from physical mixtures and especially in solid dispersions compared to piroxicam pure and treated powders. PXRD and DSC results were confirmed the reduction of crystalline form of piroxicam. FT-IR analysis did not show any physicochemical interaction between drug and carriers in the solid dispersion formulations. Conclusion: Dissolution rate was dependent on the type and ratio of drug: carrier as well as pH of dissolution medium. Dissolution data of formulations were fitted well in to the linear Weibull as well as non-linear logistic and a suggested models.

Stability and drug dissolution evaluation of Qingkailing soft/hard ...

African Journals Online (AJOL)

HPLC-DAD) method was developed ... stability and drug dissolution, which may affect the biopharmaceutics and the clinical effects of the drug. ... behavior may also affect the pharmacokinetic ..... of enzymes and intrinsic factors in stomach and.

Initial dissolution rate of a Japanese simulated high-level waste glass P0798 as a function of pH and temperature measured by using micro-channel flow-through test method

International Nuclear Information System (INIS)

Inagaki, Yaohiro; Makigaki, Hikaru; Idemitsu, Kazuya; Arima, Tatsumi; Mitsui, Sei-ichiro; Noshita, Kenji

2012-01-01

Aqueous dissolution tests were performed for a Japanese type of simulated high-level waste (HLW) glass P0798 by using a newly developed test method of micro-channel flow-through (MCFT) method, and the initial dissolution rate of glass matrix, r 0 , was measured as a function of solution pH (3-11) and temperature (25-90degC) precisely and consistently for systematic evaluation of the dissolution kinetics. The MCFT method using a micro-channel reactor with a coupon shaped glass specimen has the following features to provide precise and consistent data on the glass dissolution rate: (1) any controlled constant solution condition can be provided over the test duration; (2) the glass surface area actually reacting with solution can be determined accurately; and (3) direct and totally quantitative analyses of the reacted glass surface can be performed for confirming consistency of the test results. The present test results indicated that the r 0 shows a 'V-shaped' pH dependence with a minimum at around pH 6 at 25degC, but it changes to a 'U-shaped' one with a flat bottom at neutral pH at elevated temperatures of up to 90degC. The present results also indicated that the r 0 increases with temperature according to an Arrhenius law at any pH, and the apparent activation energy evaluated from Arrhenius relation increases with pH from 54 kJ/mol at pH 3 to 76 kJ/mol at pH 10, which suggests that the dissolution mechanism changes depending on pH. (author)

Mechanism and Kinetics for the Dissolution of Apatitic Materials in Acid Solutions

Directory of Open Access Journals (Sweden)

Calmanovici C.E.

1997-01-01

Full Text Available Abstract - This work concerns the study of the digestion step in the production process of phosphoric acid. Some qualitative experiments indicate that the difference between the pH at the surface of the phosphate and that in the bulk of the solution is negligible and that the dissolution is controlled by diffusion of products away from the phosphate particle. In further experiments, to isolate the dissolution phenomenon from the formation of calcium sulfate, the sulfuric acid normally used industrially is replaced by hydrochloric acid. The phosphate material used in our experiments is a model apatitic material: synthetic hydroxyapatite (HAP. The dissolution of calcium hydroxyapatite was studied with increasing amounts of calcium and phosphate at different temperatures. A simple method was developed for this observation based on the time required for complete dissolution of the HAP powder. The results confirm that the dissolution is controlled by a diffusional process through an interface of calcium and phosphate ions released from the solid surface. A kinetic model for the dissolution of apatitic materials is proposed which assumes a shrinking particle behaviour controlled by diffusion of calcium ions. The experimental results are fitted to this model to determine the mass transfer constant for HAP dissolution in acid solutions. The activation energy of the reaction is about 14kJ/mol. This study was carried on in conditions similar to the industrial ones for the production of phosphoric acid by the dihydrate-process

Validation and Application of a New Reversed Phase HPLC Method for In Vitro Dissolution Studies of Rabeprazole Sodium in Delayed-Release Tablets

Directory of Open Access Journals (Sweden)

Md. Saddam Nawaz

2013-01-01

Full Text Available The purpose of this study was to develop and validate a new reversed phase high performance liquid chromatographic (RP-HPLC method to quantify in vitro dissolution assay of rabeprazole sodium in pharmaceutical tablet dosage form. Method development was performed on C 18, 100×4.6 mm ID, and 10 μm particle size column, and injection volume was 20 μL using a diode array detector (DAD to monitor the detection at 280 nm. The mobile phase consisted of buffer: acetonitrile at a ratio of 60 : 40 (v/v, and the flow rate was maintained at 1.0 mL/min. The method was validated in terms of suitability, linearity, specificity, accuracy, precision, stability, and sensitivity. Linearity was observed over the range of concentration 0.05–12.0 μg/mL, and the correlation coefficient was found excellent >0.999. The method was specific with respect to rabeprazole sodium, and the peak purity was found 99.99%. The method was precise and had relative standard deviations (RSD less than 2%. Accuracy was found in the range of 99.9 to 101.9%. The method was robust in different variable conditions and reproducible. This proposed fast, reliable, cost-effective method can be used as quality control tool for the estimation of rabeprazole sodium in routine dissolution test analysis.

Monitoring the hydrolyzation of aspirin during the dissolution testing for aspirin delayed-release tablets with a fiber-optic dissolution system

Directory of Open Access Journals (Sweden)

Yan Wang

2012-10-01

Full Text Available The purpose of this study was to investigate the hydrolyzation of aspirin during the process of dissolution testing for aspirin delayed-release tablets. Hydrolysis product of salicylic acid can result in adverse effects and affect the determination of dissolution rate assaying. In this study, the technique of differential spectra was employed, which made it possible to monitor the dissolution testing in situ. The results showed that the hydrolyzation of aspirin made the percentage of salicylic acid exceed the limit of free salicylic acid (4.0, and the hydrolyzation may affect the quality detection of aspirin delayed-release tablets. Keywords: Aspirin delayed-release tablets, Drug dissolution test, Fiber-optic dissolution system, UV–vis spectrum

Solvents effects on crystallinity and dissolution of β-artemether.

Science.gov (United States)

Xu, Jianghui; Singh, Vikramjeet; Yin, Xianzhen; Singh, Parbeen; Wu, Li; Xu, Xiaonan; Guo, Tao; Sun, Lixin; Gui, Shuangying; Zhang, Jiwen

2017-03-01

β-artemether (ARM) is a widely used anti-malarial drug isolated from the Chinese antimalarial plant, Artemisia annua. The solvent effects on crystal habits and dissolution of ARM were thoroughly investigated and discussed herein. The ARM was recrystallized in nine different solvents of varied polarity, namely, methanol, ethanol, isopropanol, tetrahydrofuran, dichloromethane, trichloromethane, ethyl acetate, acetone and hexane by solvent evaporation method. The obtained crystals were morphologically characterized using scanning electron microscope (SEM). The average sizes of crystals were 1.80-2.64 μm calculated from microscopic images using Image-Pro software. No significant change in chemical structure was noticed after recrystallization and the specific band at 875 cm -1 wavenumber (C-O-O-C) confirmed the presence of most sensitive functional group in the ARM chemical structure. The existence and production of two polymorphic forms, polymorph A and polymorph B, was confirmed by differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). The data suggested that the fabrication of polymorph B can be simply obtained from the recrystallization of ARM in a specific solvent. Significant effects of solvent polarity, crystals shapes and sizes on drug dissolution were noticed during in vitro dissolution test. The release kinetics were calculated and well fitted by the Higuchi and Hixon-Crowell models. The ARM-methanol and ARM-hexane showed highest and slowest dissolution, respectively, due to the effects of solvent polarity and crystal morphologies. Overall, proper selection of the solvents for the final crystallization of ARM helps to optimize dissolution and bioavailability for a better delivery of anti-malarial drug.

Radioactivity measurement of 18F in 16 ml vials for calibration of radionuclide calibrators

International Nuclear Information System (INIS)

Wurdiyanto, Gatot; Marsoem, Pujadi; Candra, Hermawan; Wijono, Paidi

2012-01-01

Fluorine-18 is obtained through the reaction 18 O(p, n) 18 F using a cyclotron that is situated in a hospital in Jakarta. Standardization of the 18 F solution is performed by gamma spectrometry using calibration sources of 152 Eu, 60 Co and 137 Cs that have traceability to the International System of units (SI). The activities in the 16 ml vials that were used for calibrating the radionuclide calibrators were between 1 and 2 GBq, with expanded uncertainties of 3.8%. The expanded uncertainty, at a coverage factor of k=2, on the derived calibration factor for the radionuclide calibrator was 6.6%. - Highlights: ► PTKMR–BATAN as a NMI of Indonesia is required to have procedures to calibrate the radionuclide calibrators. ► Standardizations were carried out on a solution of [ 18 F]FDG using gamma spectrometry. ► The volume of 18 F solutions used was 16 ml because this is the volume often used in hospitals. ► The Secondary Standard ionization chamber is a CRC-7BT Capintec radionuclide calibrator. ► A dial setting for 16 ml of [ 18 F]FDG solution in a vial is 443 for the Capintec dose calibrator.

Vaccine Wastage Assessment After Introduction of Open Vial Policy in Surat Municipal Corporation Area of India.

Science.gov (United States)

Patel, Prakash B; Rana, Jayesh J; Jangid, Sunil G; Bavarva, Neha R; Patel, Manan J; Bansal, Raj Kumar

2015-12-08

As per the vaccine management policy of the Government of India all vaccine vials opened for an immunization session were discarded at the end of that session, irrespective of the type of vaccine or the number of doses remaining in the vial prior to 2013. Subsequently, open vial policy (OVP) was introduced in 2013 and should reduce both vaccine wastage as well as governmental healthcare costs for immunization. This study evaluates the vaccine wastage after introduction of the OVP and its comparison with the previous study of vaccine wastage in Surat city before implementation of OVP. It needs to mention that the vaccine policy for this period under comparison was uniform except for the OVP. Information regarding vaccine doses consumed and children vaccinated during immunization sessions of 24 urban health centers (UHCs) of Surat city were retrieved for the period of January 1st, 2014 to March 31st, 2014. The data were analyzed to estimate vaccine wastage rate (WR) and vaccine wastage factor (WF). In order to assess the impact of OVP, vaccine WR of this study was compared with that of previous study conducted in Surat city during January 1st, 2012 to March 31st, 2012. The vaccine WR for oral polio vaccine (OPV) has decreased from 25% to 13.62%, while the WRs for DPT, hepatitis B virus (HBV) and the pentavalent vaccine combinedly have decreased from 17.94% to 8.05%. Thus, by implementation of OVP, an estimated 747 727 doses of OPV and 343 725 doses of diphtheria, pertussis and tetanus toxoid vaccine (DPT), HBV and the pentavalent vaccines combinedly have been saved in Surat city of India in a year. The implementation of the OVP in Surat city has led to a significant lowering in the vaccine wastage, leading to savings due to lower vaccine requirements. © 2016 by Kerman University of Medical Sciences.

Feasibility of Using Gluconolactone, Trehalose and Hydroxy-Propyl Gamma Cyclodextrin to Enhance Bendroflumethiazide Dissolution Using Lyophilisation and Physical Mixing Techniques

Directory of Open Access Journals (Sweden)

Ashraf Saleh

2018-02-01

Full Text Available Purpose: Hydrophobic drugs are facing a major challenge in dissolution rate enhancement and solubility in aqueous solutions; therefore, a variety of methods have been used to improve dissolution rate and/or solubility of bendroflumethiazide as a model hydrophobic drug. Methods: In this study, two main methods (physical mixing and lyophilisation were used with gluconolactone, hydroxyl propyl γ-ccyclodextrin, and trehalose to explore this challenge. Bendroflumethiazide, practically insoluble in water, was mixed with one of the three excipients gluconolactone, hydroxyl propyl γ-cyclodextrin, and trehalose in three different ratios 1:1, 1:2, 1:5. To the best of our knowledge, the dissolution of the drug has not been previously enhanced by using either these methods or any of the used excipients. Samples containing drug and each of the excipients were characterized via dissolution testing, Fourier Transform infra-red spectroscopy, differential scanning calorimetry, and scanning electron microscopy. Results: The used methods showed a significant enhancement in dug dissolution rate; physical mixing significantly, p < 0.05, increased the percentage of the drug released with time; for example, bendroflumethiazide dissolution in distilled water was improved from less than 20% to 99.79% within 90 min for physically mixed drug-cyclodextrin 1:5. The lyophilisation process was enhanced and the drug dissolution rate and the highest drug dissolution was achieved for (drug-gluconolactone 1:1 with 98.98% drug release within 90 min. Conclusions: the physical mixing and freeze drying processes significantly increased the percentage of drug release with time.

Use of the co-grinding method to enhance the dissolution behavior of a poorly water-soluble drug: generation of solvent-free drug-polymer solid dispersions.

Science.gov (United States)

Yang, Caiqin; Xu, Xiujuan; Wang, Jing; An, Zhiqian

2012-01-01

The solid dispersion (SD) technique is the most effective method for improving the dissolution rate of poorly water-soluble drugs. In the present work, SDs of the Ca2+ channel blocker dipfluzine (DF) with polyvinylpyrrolidone K30 (PVP) and poloxamer 188 (PLXM) were prepared by the powder solid co-grinding method under a solvent-free condition. The properties of all SDs and physical mixtures were investigated by X-ray diffraction, Fourier-transform infrared, differential scanning calorimetry, scanning electron microscopy, dissolution test, and particles size determination. Eutectic compounds were produced between the DF and PLXM matrix during the co-grinding process, whereas glass suspension formed in the SDs with PVP carrier. Hydrogen bond formation was not observed between DF and carriers and DF was microcrystalline state in the PVP and PLXM matrices. The solubility of DF in different concentration of carriers at 25, 31, and 37°C was investigated; the values obtained were used to calculate the thermodynamic parameters of interaction between DF and carriers. The Gibbs free energy (ΔrGθ) values were negative, indicating the spontaneous nature of dispersing DF into the carriers. Moreover, entropy is the drive force when DF disperses into the matrix of PVP, while, enthalpy-driven dispersing encounters in the PLXM carrier. All the SDs of DF/carriers showed a considerably higher dissolution rate than pure DF and the corresponding physical mixtures. The cumulative dissolution rate at 10 min of the SD with a 1 : 3 DF/carrier ratio increased 5.1-fold for PVP and 5.5-fold for PLXM.

Aqueous dissolution rates of uranium oxides

International Nuclear Information System (INIS)

Steward, S.A.; Mones, E.T.

1994-10-01

An understanding of the long-term dissolution of waste forms in groundwater is required for the safe disposal of high level nuclear waste in an underground repository. The main routes by which radionuclides could be released from a geological repository are the dissolution and transport processes in groundwater flow. Because uranium dioxide is the primary constituent of spent nuclear fuel, the dissolution of its matrix in spent fuel is considered the rate-limiting step for release of radioactive fission products. The purpose of our work has been to measure the intrinsic dissolution rates of uranium oxides under a variety of well-controlled conditions that are relevant to a repository and allow for modeling. The intermediate oxide phase U 3 O 8 , triuranium octaoxide, is quite stable and known to be present in oxidized spent fuel. The trioxide, UO 3 , has been shown to exist in drip tests on spent fuel. Here we compare the results of essentially identical dissolution experiments performed on depleted U 3 O 8 and dehyrated schoepite or uranium trioxide monohydrate (UO 3 ·H 2 O). These are compared with earlier work on spent fuel and UO 2 under similar conditions

Effect of drug loading method against drug dissolution mechanism of encapsulated amoxicillin trihydrate in matrix of semi-IPN chitosan-poly(N-vinylpyrrolidone) hydrogel with KHCO3 as pore forming agent in floating drug delivery system

Science.gov (United States)

Fimantari, Khansa; Budianto, Emil

2018-04-01

Helicobacterpylori infection can be treated using trihydrate amoxicillin. However, this treatment is not effective enough, as the conventional dosage treatment has a relatively short retention time in the human stomach. In the present study, the amoxicillin trihydrate drug will be encapsulated into a semi-IPN K-PNVP hydrogel matrix with 7,5% KHCO3 as a pore-forming agent. The encapsulated drug is tested with in vitro method to see the efficiency of its encapsulation and dissolution. The hydrogel in situ loading produces an encapsulation efficiency value. The values of the encapsulation efficiency are 95% and 98%, while post loading hydrogel yields an encapsulation efficiency value is 77% and the dissolution is 84%. The study of drug dissolution mechanism was done by using mathematical equation model to know its kinetics and its mechanism of dissolution. The post loading hydrogel was done by using thefirst-order model, while hydrogel in situ loading used Higuchi model. The Korsmeyer-Peppas model shows that post loading hydrogel dissolution mechanism is a mixture of diffusion and erosion, and in situ loading hydrogel in the form of diffusion. It is supported by the results of hydrogel characterization, before and after dissolution test with an optical microscope. The results of the optical microscope show that the hydrogel surface before and after the dissolution tested for both methods shows the change becomes rougher.

Dissolution of metallic uranium in alkalis

International Nuclear Information System (INIS)

Mondino, Angel V.; Wilkinson, Maria V.; Manzini, Alberto C.

1999-01-01

The dissolution of U metallic foils has been studied in the framework of the development of an improved 99 Mo-production process. The best conditions for the dissolution of uranium foils of approximately 150 μm are the following: a) NaClO concentrations of 0.20 and 0.23 M with NaOH of 0.27 and 0.31 M respectively; b) temperature of the solution, 70 C degrees; c) volume of the solution, 15 ml / cm 2 of uranium foil; d) dissolution time, 30 minutes. (author)

Low temperature dissolution flowsheet for plutonium metal

Energy Technology Data Exchange (ETDEWEB)

Daniel, W. E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Almond, P. M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Rudisill, T. S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2016-05-01

The H-Canyon flowsheet used to dissolve Pu metal for PuO₂ production utilizes boiling HNO₃. SRNL was requested to develop a complementary dissolution flowsheet at two reduced temperature ranges. The dissolution and H₂ generation rates of Pu metal were investigated using a dissolving solution at ambient temperature (20-30 °C) and for an intermediate temperature of 50-60 °C. Additionally, the testing included an investigation of the dissolution rates and characterization of the off-gas generated from the ambient temperature dissolution of carbon steel cans and the nylon bags that contain the Pu metal when charged to the dissolver.

Physical heterogeneity control on effective mineral dissolution rates

Science.gov (United States)

Jung, Heewon; Navarre-Sitchler, Alexis

2018-04-01

Hydrologic heterogeneity may be an important factor contributing to the discrepancy in laboratory and field measured dissolution rates, but the governing factors influencing mineral dissolution rates among various representations of physical heterogeneity remain poorly understood. Here, we present multiple reactive transport simulations of anorthite dissolution in 2D latticed random permeability fields and link the information from local grid scale (1 cm or 4 m) dissolution rates to domain-scale (1m or 400 m) effective dissolution rates measured by the flux-weighted average of an ensemble of flow paths. We compare results of homogeneous models to heterogeneous models with different structure and layered permeability distributions within the model domain. Chemistry is simplified to a single dissolving primary mineral (anorthite) distributed homogeneously throughout the domain and a single secondary mineral (kaolinite) that is allowed to dissolve or precipitate. Results show that increasing size in correlation structure (i.e. long integral scales) and high variance in permeability distribution are two important factors inducing a reduction in effective mineral dissolution rates compared to homogeneous permeability domains. Larger correlation structures produce larger zones of low permeability where diffusion is an important transport mechanism. Due to the increased residence time under slow diffusive transport, the saturation state of a solute with respect to a reacting mineral approaches equilibrium and reduces the reaction rate. High variance in permeability distribution favorably develops large low permeability zones that intensifies the reduction in mixing and effective dissolution rate. However, the degree of reduction in effective dissolution rate observed in 1 m × 1 m domains is too small (equilibrium conditions reduce the effective dissolution rate by increasing the saturation state. However, in large domains where less- or non-reactive zones develop, higher

Evaluation and comparison of in-vitro dissolution profiles for different ...

African Journals Online (AJOL)

EB

Food and Medicine quality Control Laboratory, Food, Medicine and ... Methods: Dissolution profiles for nine brands of amoxicillin capsules ... Senior pharmaceutical analysis expert. Food ..... Overall, it can be recommended that drug regulatory.

Dissolution of Material and Test reactor Fuel in an H-Canyon Dissolver

Energy Technology Data Exchange (ETDEWEB)

Daniel, W. E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Rudisill, T. S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); O' Rourke, P. E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-01-26

In an amended record of decision for the management of spent nuclear fuel (SNF) at the Savannah River Site, the US Department of Energy has authorized the dissolution and recovery of U from 1000 bundles of Al-clad SNF. The SNF is fuel from domestic and foreign research reactors and is typically referred to as Material Test Reactor (MTR) fuel. Bundles of MTR fuel containing assemblies fabricated from U-Al alloys (or other U compounds) are currently dissolved using a Hg-catalyzed HNO3 flowsheet. Since the development of the existing flowsheet, improved experimental methods have been developed to more accurately characterize the offgas composition and generation rate during laboratory dissolutions. Recently, these new techniques were successfully used to develop a flowsheet for the dissolution of High Flux Isotope Reactor (HFIR) fuel. Using the data from the HFIR dissolution flowsheet development and necessary laboratory experiments, the Savannah River National Laboratory (SRNL) was requested to define flowsheet conditions for the dissolution of MTR fuels. With improved offgas characterization techniques, SRNL will be able define the number of bundles of fuel which can be charged to an H-Canyon dissolver with much less conservatism.

Improved Dissolution and Oral Bioavailability of Celecoxib by a Dry Elixir System.

Science.gov (United States)

Cho, Kwan Hyung; Jee, Jun-Pil; Yang, Da A; Kim, Sung Tae; Kang, Dongjin; Kim, Dae-Young; Sim, Taeyong; Park, Sang Yeob; Kim, Kyeongsoon; Jang, Dong-Jin

2018-02-01

The purpose of this study was to develop and evaluate a dry elixir (DE) system for enhancing the dissolution rate and oral bioavailability of celecoxib. DE system has been used for improving solubility, oral bioavailability of poorly water-soluble drugs. The encapsulated drugs or solubilized drugs in the matrix are rapidly dissolved due to the co-solvent effect, resting in both an enhanced dissolution and bioavailability. DEs containing celecoxib were prepared by spray-drying method and characterized by morphology, drug/ethanol content, drug crystallinity, dissolution rate and oral bioavailability. The ethanol content and drug content in DE system could be easily altered by controlling the spraydrying conditions. The dissolution profile of celecoxib from DE proved to be much higher than that of celecoxib powder due to the nano-structured matrix, amorphous state and encapsulated ethanol. The bioavailability of celecoxib from DEs was compared with celecoxib powder alone and commercial product (Celebrex®) in rats. In particular, blood concentrations of celecoxib form DE formulation were much greater than those of native celecoxib and market product. The data demonstrate that the DE system could provide an useful solid dosage form to enhance the solubility, dissolution rate and oral bioavailability of celecoxib.

Dissolution rates of DWPF glasses from long-term PCT

International Nuclear Information System (INIS)

Ebert, W.L.; Tam, S.W.

1996-01-01

We have characterized the corrosion behavior of several Defense Waste Processing Facility (DWPF) reference waste glasses by conducting static dissolution tests with crushed glasses. Glass dissolution rates were calculated from measured B concentrations in tests conducted for up to five years. The dissolution rates of all glasses increased significantly after certain alteration phases precipitated. Calculation of the dissolution rates was complicated by the decrease in the available surface area as the glass dissolves. We took the loss of surface area into account by modeling the particles to be spheres, then extracting from the short-term test results the dissolution rate corresponding to a linear decrease in the radius of spherical particles. The measured extent of dissolution in tests conducted for longer times was less than predicted with this linear dissolution model. This indicates that advanced stages of corrosion are affected by another process besides dissolution, which we believe to be associated with a decrease in the precipitation rate of the alteration phases. These results show that the dissolution rate measured soon after the formation of certain alteration phases provides an upper limit for the long-term dissolution rate, and can be used to determine a bounding value for the source term for radionuclide release from waste glasses. The long-term dissolution rates measured in tests at 20,000 per m at 90 degrees C in tuff groundwater at pH values near 12 for the Environmental Assessment glass and glasses made with SRL 131 and SRL 202 frits, respectively

[Comparison in dissolution behavior of ethical and over-the counter scopolamine butylbromide].

Science.gov (United States)

Suzuki, Ichie; Miyazaki, Yasunori; Uchino, Tomonobu; Kagawa, Yoshiyuki

2011-01-01

Marketing authorization holders do not disclose any information on the pharmaceutical properties of over-the-counter drugs (OTC). When a drug is switched from a prescription drug to OTC, pharmacists can acquire that information from the corresponding ethical drug (ED) through the package insert, interview form, and so on. However, the pharmaceutical equivalence between ED and OTC is unclear. In this study, we examined the drug dissolution behavior of both ED and OTCs containing scopolamine butylbromide. Dissolution tests were performed by the paddle method using Japanese Pharmacopeia (JP) XV test fluids at pH 1.2, 4.0 and 6.8 and water based on the guidelines for bioequivalence studies of generic products. The dissolution profiles of OTCs differed significantly from ED showing a similarity factor (f2) value ranging from 8.9 to 42.9. Time until 85% dissolution ranged from 23 to 95 min and from 17 to 174 min at pH 1.2 and pH 6.8, respectively. Then JP XV disintegration tests were conducted to investigate differences in the disintegration process. The disintegration time of preparations showing delayed dissolution was prolonged compared to that of others, suggesting that the disintegration of the tablet or capsule is one of the important factors affecting the drug dissolution. These differences in the disintegration and drug dissolution might cause differences in the bioavailability of the drug. For patient safety, more detailed product information of OTCs should be supplied by the manufacturer, and not be assumed from that of corresponding ED.

Anodic dissolution and corrosion of alloy Cu30Ni in chloride solutions

International Nuclear Information System (INIS)

Zolotarev, E.I.

1989-01-01

The anodic and corrosion behavior of alloy Cu30Ni is studied in a solution of 3 N NaCl + 0.01 N HCl by a radiometric method using gamma isotopes of 58 Co (as a marker for Ni) and 64 Cu in combination with electrochemical measurements. It was established that under stationary conditions there was uniform dissolution of the alloy both during free corrosion and anodic polarization. The authors obtained partial anodic dissolution curves for the components of the alloy. It was shown that the dissolution kinetics differed from the mechanisms controlling dissolution of the corresponding pure metals. During corrosion of the alloy in an oxygen atmosphere a back precipitation of copper on the surface of the alloy was not observed. The characteristics observed in the corrosion-electrochemical behavior of the alloy in concentrated chloride solutions can be explained by the presence of Ni on the surface of the dissolving alloy

Simfuel dissolution studies in granitic groundwater

International Nuclear Information System (INIS)

Casas, I.; Caceci, M.S.; Bruno, J.; Sandino, A.; Ollila, K.

1991-09-01

The dissolution behavior of an unirradiated chemical analogue of spent nuclear fuel (SIMFUEL) has been studied in the presence of two different synthetic groundwater at 25 deg C and under both oxic and anoxic conditions. The release of U, Mo, Ba, Y and Sr was monitored during static (batch) leaching experiments of long duration (about 250 days). Preliminary results from continuous flow-through reactor experiments are also reported. The results obtained indicate the usefulness and limitations of SIMFUEL in the study of the kinetics and mechanism of dissolution of the minor components of spent nuclear fuel. Molybdenum, barium and strontium have shown a trend to congruent dissolution with the SIMFUEL matrix after a higher initial fractional release. Yttrium release has been found to be solubility controlled under the experimental conditions. A clear dependence on the partial pressure of O 2 of the rates of dissolution of uranium has been observed

SIMFUEL dissolution studies in granitic groundwater

International Nuclear Information System (INIS)

Casas, I.; Caceci, M.S.; Bruno, J; Sandino, A.

1991-09-01

The dissolution behavior of an unirradiated chemical analogue of spent nuclear fuel (SIMFUEL) has been studied in the presence of two different synthetic groundwaters at 25 degrees C and under both oxic and anoxic conditions. The release of U, Mo, Ba, Y and Sr was monitored during static (batch) leaching experiments of long duration (about 250 days). Preliminary results from continuous flow-through reactor experiments are also reported. The results obtained indicate the usefulness and limitations of SIMFUEL in the study of the kinetics and mechanism of dissolution of the minor components of spent nuclear fuel. Molybdenum, barium and strontium have shown a trend of congruent dissolution with the SIMFUEL matrix after a higher initial fractional release has been found to be solubility controlled under the experimental conditions. A clear dependence on the partial pressure of O 2 of the rate of dissolution of uranium has been observed. (au)

Overview of chemical modeling of nuclear waste glass dissolution

International Nuclear Information System (INIS)

Bourcier, W.L.

1991-02-01

Glass dissolution takes place through metal leaching and hydration of the glass surface accompanied by development of alternation layers of varying crystallinity. The reaction which controls the long-term glass dissolution rate appears to be surface layer dissolution. This reaction is reversible because the buildup of dissolved species in solution slows the dissolution rate due to a decreased dissolution affinity. Glass dissolution rates are therefore highly dependent on silica concentrations in solution because silica is the major component of the alteration layer. Chemical modeling of glass dissolution using reaction path computer codes has successfully been applied to short term experimental tests and used to predict long-term repository performance. Current problems and limitations of the models include a poorly defined long-term glass dissolution mechanism, the use of model parameters determined from the same experiments that the model is used to predict, and the lack of sufficient validation of key assumptions in the modeling approach. Work is in progress that addresses these issues. 41 refs., 7 figs., 2 tabs

Fundamental study on dissolution behavior of poly(methyl methacrylate) by quartz crystal microbalance

Science.gov (United States)

Konda, Akihiro; Yamamoto, Hiroki; Yoshitake, Shusuke; Kozawa, Takahiro

2016-03-01

Ionizing radiations such as extreme ultraviolet (EUV) and electron beam (EB) are the most promising exposure source for next-generation lithographic technology. In the realization of high resolution lithography, it is necessary for resist materials to improve the trade-off relationship among sensitivity, resolution, and line width roughness (LWR). In order to overcome them, it is essential to understand basic chemistry of resist matrices in resist processes. In particular, the dissolution process of resist materials is a key process. Therefore, it is essential for next-generation resist design for ionizing radiation to clarify the dissolution behavior of the resist film into developer. However, the details in dissolution process of EUV and EB resist films have not been investigated thus far. In this study, main chain scission and dissolution behavior of poly(methyl methacrylate) (PMMA) as main chain scission type resist was investigated using quartz crystal microbalance (QCM) method and gel permeation chromatography (GPC) in order to understand the relationship between the degree of PMMA degradation and dissolution behavior. The relationship between the molecular weight after irradiation and the swelling behavior was clarified.

Dissolution studies of spent nuclear fuels

International Nuclear Information System (INIS)

1991-02-01

To obtain quantitative data on the dissolution of high burnup spent nuclear fuel, dissolution study have been carried out at the Department of Chemistry, JAERI, from 1984 under the contract with STA entitled 'Reprocessing Test Study of High Burnup Fuel'. In this study PWR spent fuels of 8,400 to 36,100 MWd/t in averaged burnup were dissolved and the chemical composition and distribution of radioactive nuclides were measured for insoluble residue, cladding material (hull), off-gas and dissolved solution. With these analyses basic data concerning the dissolution and clarification process in the reprocessing plant were accumulated. (author)

Dissolution testing of orally disintegrating tablets.

Science.gov (United States)

Kraemer, Johannes; Gajendran, Jayachandar; Guillot, Alexis; Schichtel, Julian; Tuereli, Akif

2012-07-01

For industrially manufactured pharmaceutical dosage forms, product quality tests and performance tests are required to ascertain the quality of the final product. Current compendial requirements specify a disintegration and/or a dissolution test to check the quality of oral solid dosage forms. These requirements led to a number of compendial monographs for individual products and, at times, the results obtained may not be reflective of the dosage form performance. Although a general product performance test is desirable for orally disintegrating tablets (ODTs), the complexity of the release controlling mechanisms and short time-frame of release make such tests difficult to establish. For conventional oral solid dosage forms (COSDFs), disintegration is often considered to be the prerequisite for subsequent dissolution. Hence, disintegration testing is usually insufficient to judge product performance of COSDFs. Given the very fast disintegration of ODTs, the relationship between disintegration and dissolution is worthy of closer scrutiny. This article reviews the current status of dissolution testing of ODTs to establish the product quality standards. Based on experimental results, it appears that it may be feasible to rely on the dissolution test without a need for disintegration studies for selected ODTs on the market. © 2012 The Authors. JPP © 2012 Royal Pharmaceutical Society.

Importance of surface structure on dissolution of fluorite

DEFF Research Database (Denmark)

Godinho, Jose; Piazolo, Sandra; Balic Zunic, Tonci

2014-01-01

forming the initial surface and its inclination to the closest stable planes, which are specific for each surface orientation. During an initial dissolution regime dissolution rates decrease significantly, even though the total surface area increases. During a second dissolution regime, some surfaces...... by the relative stability of the planes and type of edges that constitute a surface needs to be considered. Significant differences between dissolution rates calculated based on surface area alone, and based on surface reactivity are expected for materials with the fluorite structure....

Enhancement of the dissolution rate and bioavailability of fenofibrate by a melt-adsorption method using supercritical carbon dioxide

Directory of Open Access Journals (Sweden)

Cha KH

2012-10-01

Full Text Available Kwang-Ho Cha,1,3 Kyung-Jin Cho,3 Min-Soo Kim,4 Jeong-Soo Kim,3 Hee Jun Park,1,3 Junsung Park,1,3 Wonkyung Cho,1,3 Jeong-Sook Park,3 Sung-Joo Hwang1,21Yonsei Institute of Pharmaceutical Sciences, 2College of Pharmacy, Yonsei University, Incheon, Republic of Korea; 3College of Pharmacy, Chungnam National University, Daejeon, Republic of Korea; 4Department of Pharmaceutical Engineering, Inje University, Gimhae, Republic of KoreaBackground: The aim of this study was to enhance the bioavailability of fenofibrate, a poorly water-soluble drug, using a melt-adsorption method with supercritical CO2.Methods: Fenofibrate was loaded onto Neusilin® UFL2 at different weight ratios of fenofibrate to Neusilin UFL2 by melt-adsorption using supercritical CO2. For comparison, fenofibrate-loaded Neusilin UFL2 was prepared by solvent evaporation and hot melt-adsorption methods. The fenofibrate formulations prepared were characterized by differential scanning calorimetry, powder x-ray diffractometry, specific surface area, pore size distribution, scanning electron microscopy, and energy-dispersive x-ray spectrometry. In vitro dissolution and in vivo bioavailability were also investigated.Results: Fenofibrate was distributed into the pores of Neusilin UFL2 and showed reduced crystal formation following adsorption. Supercritical CO2 facilitated the introduction of fenofibrate into the pores of Neusilin UFL2. Compared with raw fenofibrate, fenofibrate from the prepared powders showed a significantly increased dissolution rate and better bioavailability. In particular, the area under the drug concentration-time curve and maximal serum concentration of the powders prepared using supercritical CO2 were 4.62-fold and 4.52-fold greater than the corresponding values for raw fenofibrate.Conclusion: The results of this study highlight the usefulness of the melt-adsorption method using supercritical CO2 for improving the bioavailability of fenofibrate.Keywords: fenofibrate

Educación vial y movilidad en la Infancia

Directory of Open Access Journals (Sweden)

Fernando Martín Poó

Full Text Available Resumen:La motorización creciente de los desplazamientos ha convertido al ambiente urbano en un lugar cada vez más hostil para los niños y niñas, quienes se encuentran entre los grupos humanos más vulnerables del tránsito. En esta etapa del desarrollo, la educación puede ser una herramienta clave para prevenir comportamientos de riesgo y promocionar hábitos de movilidad más saludables. El presente trabajo discute algunos aspectos relacionados con la educación vial en la infancia. Se destaca la importancia de considerar los patrones de movilidad típicos de cada edad, y de promover el uso de medios de transporte más saludables, equitativos y sustentables. Se señala además la necesidad de complementar las acciones educativas con intervenciones multi-sectoriales a diferente nivel.

Formulation and evaluation of a montelukast sodium orally disintegrating tablet with a similar dissolution profile as the marketed product.

Science.gov (United States)

Chen, Yong; Feng, Tingting; Li, Yong; Du, Bin; Weng, Weiyu

2017-03-01

A major challenge of orally disintegrating tablet (ODT) development is predicting its bioequivalence to its corresponding marketed product. Therefore, comparing ODT dissolution profiles to those of the corresponding marketed product is very important. The objective of this study was to develop a 5.2-mg montelukast sodium (MS) ODT with a similar dissolution profile to that of the marketed chewable tablet. Dissolution profiles were examined in different media to screen each formulation. We found that MS dissolution from ODTs in acidic medium heavily depended on manufacturing methods. All MS ODTs prepared using direct compression rapidly disintegrated in acidic medium. However, dispersed MS powders aggregated into sticky masses, resulting in slow dissolution. In contrast, MS ODTs prepared using wet granulation had much faster dissolution rates in acidic medium with no obvious aggregation. Additionally, the optimized formulation, prepared using wet granulation, displayed similar dissolution profiles to the marketed reference in all four types of media examined (f 2  >   50). The in vitro disintegration time of the optimized ODT was 9.5 ± 2.4 s, which meets FDA requirements. In conclusion, the wet granulation preparation method of MS ODTs resulted in a product with equivalent dissolution profiles as those of the marketed product.

Cesium Hydroxide Fusion Dissolution of Analytical Reference Glass-1 in Both Powder and Shard Form

International Nuclear Information System (INIS)

Coleman, C.J.; Spencer, W.A.

1998-04-01

CsOH has been shown to be an effective and convenient dissolution reagent for Analytical Reference Glass-1 (ARG-1). This glass standard was prepared from nonradioactive DWPF Start-up Glass. Therefore, its composition is similar to DWPF product glass and many of the glass matrices prepared at SRTC.The principal advantage of the CsOH fusion dissolution is that the reagent does not add the alkali metals Li, Na, and K usually needed by SRS customers. Commercially available CsOH is quite pure so that alkali metals can be measured accurately, often without blank corrections. CsOH fusions provide a single dissolution method for applicable glass to replace multiple dissolution schemes used by most laboratories. For example, SRTC glass samples are most commonly dissolved with a Na 2 O 2 -NaOH fusion (ref.1) and a microwave- assisted acid dissolution with HNO 3 -HF-H 3 BO 3 -HCl (ref.2). Othe laboratories use fusion methods based on KOH, LiBO 2 , and Na 2 CO 3 CsOH fusion approach reduces by half not only the work in the dissolution laboratory, but also in the spectroscopy laboratories that must analyze each solution.Experiments also revealed that glass shards or pellets are rapidly attacked if the flux temperature is raised considerably above the glass softening point. The softening point of ARG-1 glass is near 650 degrees C. Fusions performed at 750 degrees C provided complete dissolutions and accurate elemental analyses of shards. Successful dissolution of glass shards was demonstrated with CsOH, Na 2 O 2 , NaOH, KOH, and RbOH. Ability to dissolve glass shards is of considerable practical importance. Crushing glass to a fine powder is a slow and tedious task, especially for radioactive glasses dissolved in shielded cells. CsOH fusion of glass powder or shards is a convenient, cost-effective dissolution scheme applicable in SRTC, the DWPF, and the commercial glass industry

Dissolution rate of alpha-doped UO2 in natural groundwater

International Nuclear Information System (INIS)

Ollila, Kaija; Myllykylä, Emmi; Tanhua-Tyrkkö, Merja; Lavonen, Tiina

2013-01-01

The objective of this work is to determine whether the presence of trace elements in natural groundwaters affects the dissolution rate of uranium dioxide in the presence of alpha radiation that causes radiolysis of water. The study is a part of the project Reducing Uncertainty in Performance Prediction (REDUPP) under the Seventh Framework Programme of the European Atomic Energy Community (EURATOM). The project aims to reduce uncertainties related to the extrapolation of the results of laboratory experiments to the conditions expected under geologic disposal. Thus far, synthetic groundwater has been normally used in the experiments. The synthetic groundwaters used do not contain all of the chemical elements that occur in natural groundwaters. Three natural groundwaters were chosen for the dissolution experiments with 0%, 5%, and 10% 233 U-doped UO 2 samples. These include a brackish groundwater, a saline groundwater and a low ionic strength groundwater. At the time of writing this paper, the dissolution experiments have been finished in the first groundwater, which was a moderately saline, brackish groundwater. The groundwater samples for the experiments were taken from a borehole in the Olkiluoto site in Finland. The measurements for dissolution rates were conducted under reducing conditions established using metallic iron in solution and an argon atmosphere in the glove box. The isotope dilution method was used to decrease uncertainties due to precipitation and sorption effects. The resulting dissolution rates in OL-KR6 natural groundwater were generally somewhat higher than the rates measured previously in synthetic groundwaters under similar redox conditions. No clear effect of alpha radiolysis could be seen for tests with lower SA/V, while those for higher SA/V indicated that the dissolution rate was higher for the 10% 233 U-doped UO 2 , suggesting the effect of alpha radiolysis under these conditions

Chitosan and chitosan chlorhydrate based various approaches for enhancement of dissolution rate of carvedilol

Directory of Open Access Journals (Sweden)

Shete Amol S

2012-12-01

Full Text Available Abstract Background and the purpose of the study Carvedilol nonselective β-adrenoreceptor blocker, chemically (±-1-(Carbazol-4-yloxy-3-[[2-(o-methoxypHenoxy ethyl] amino]-2-propanol, slightly soluble in ethyl ether; and practically insoluble in water, gastric fluid (simulated, TS, pH 1.1, and intestinal fluid (simulated, TS without pancreatin, pH 7.5 Compounds with aqueous solubility less than 1% W/V often represents dissolution rate limited absorption. There is need to enhance the dissolution rate of carvedilol. The objective of our present investigation was to compare chitosan and chitosan chlorhydrate based various approaches for enhancement of dissolution rate of carvedilol. Methods The different formulations were prepared by different methods like solvent change approach to prepare hydrosols, solvent evaporation technique to form solid dispersions and cogrind mixtures. The prepared formulations were characterized in terms of saturation solubility, drug content, infrared spectroscopy (FTIR, differential scanning calorimetry (DSC, powder X-ray diffraction (PXRD, electron microscopy, in vitro dissolution studies and stability studies. Results The practical yield in case of hydrosols was ranged from 59.76 to 92.32%. The drug content was found to uniform among the different batches of hydrosols, cogrind mixture and solid dispersions ranged from 98.24 to 99.89%. There was significant improvement in dissolution rate of carvedilol with chitosan chlorhdyrate as compare to chitosan and explanation to this behavior was found in the differences in the wetting, solubilities and swelling capacity of the chitosan and chitosan salts, chitosan chlorhydrate rapidly wet and dissolve upon its incorporation into the dissolution medium, whereas the chitosan base, less water soluble, would take more time to dissolve. Conclusion This technique is scalable and valuable in manufacturing process in future for enhancement of dissolution of poorly water soluble

Dissolution of FFTF vendor fuel

International Nuclear Information System (INIS)

Lerch, R.E.

1979-08-01

Dissolution experiments were performed on FFTF vendor fuel (both mechanically mixed and coprecipitated) during 1974, 1975, and 1976. A marked improvement was noted in the completeness of fuel dissolution from 1974 to 1976. The reason for this is unknown but may have been attributable to slight changes in fuel fabrication conditions. In general, the bulk of the fuel pellets tested dissolved to greater than 99.9% in nitric acid alone

Dissolution of FFTF vendor fuel

Energy Technology Data Exchange (ETDEWEB)

Lerch, R.E.

1979-08-01

Dissolution experiments were performed on FFTF vendor fuel (both mechanically mixed and coprecipitated) during 1974, 1975, and 1976. A marked improvement was noted in the completeness of fuel dissolution from 1974 to 1976. The reason for this is unknown but may have been attributable to slight changes in fuel fabrication conditions. In general, the bulk of the fuel pellets tested dissolved to greater than 99.9% in nitric acid alone.

Dissolution studies with pilot plant and actual INTEC calcines

International Nuclear Information System (INIS)

Herbst, R.S.; Garn, T.G.

1999-01-01

The dissolution of Idaho Nuclear Technology and Engineering Center (INTEC) pilot plant calcines was examined to determine solubility of calcine matrix components in acidic media. Two representatives pilot plant calcine types were studied: Zirconia calcine and Zirconia/Sodium calcine. Dissolution of these calcines was evaluated using lower initial concentrations of nitric acid than used in previous tests to decrease the [H+] concentration in the final solutions. Lower [H+] concentrations contribute to more favorable TRUEX/SREX solvent extraction flowsheet performance. Dissolution and analytical results were also obtained for radioactive calcines produced using high sodium feeds blended with non-radioactive Al(NO 3 ) 3 solutions to dilute the sodium concentration and prevent bed agglomeration during the calcination process. Dissolution tests indicated >95 wt.% of the initial calcine mass can be dissolved using the baseline dissolution procedure, with the exception that higher initial nitric acid concentrations are required. The higher initial acid concentration is required for stoichiometric dissolution of the oxides, primarily aluminum oxide. Statistically designed experiments using pilot plant calcine were performed to determine the effect of mixing rate on dissolution efficiency. Mixing rate was determined to provide minimal effects on wt.% dissolution. The acid/calcine ratio and temperature were the predominate variables affecting the wt.% dissolution, a result consistent with previous studies using other similar types of pilot plant calcines

DISSOLUTION OF IRRADIATED MURR FUEL ASSEMBLIES

Energy Technology Data Exchange (ETDEWEB)

Kyser, E.

2010-06-17

A literature survey on the dissolution of spent nuclear fuel from the University of Missouri Research Reactor (MURR) has been performed. This survey encompassed both internal and external literature sources for the dissolution of aluminum-clad uranium alloy fuels. The most limiting aspect of dissolution in the current facility configuration involves issues related to the control of the flammability of the off-gas from this process. The primary conclusion of this work is that based on past dissolution of this fuel in H-Canyon, four bundles of this fuel (initial charge) may be safely dissolved in a nitric acid flowsheet catalyzed with 0.002 M mercuric nitrate using a 40 scfm purge to control off-gas flammability. The initial charge may be followed by a second charge of up to five bundles to the same dissolver batch depending on volume and concentration constraints. The safety of this flowsheet relies on composite lower flammability limits (LFL) estimated from prior literature, pilot-scale work on the dissolution of site fuels, and the proposed processing flowsheet. Equipment modifications or improved LFL data offer the potential for improved processing rates. The fuel charging sequence, as well as the acid and catalyst concentrations, will control the dissolution rate during the initial portion of the cycle. These parameters directly impact the hydrogen and off-gas generation and, along with the purge flowrate determine the number of bundles that may be charged. The calculation approach within provides Engineering a means to determine optimal charging patterns. Downstream processing of this material should be similar to that of recent processing of site fuels requiring only minor adjustments of the existing flowsheet parameters.

Comparison of elution efficiency of 99Mo/99mTc generator using theoretical and a free web based software method

International Nuclear Information System (INIS)

Kiran Kumar, J.K.; Sharma, S.; Chakraborty, D.; Singh, B.; Bhattacharaya, A.; Mittal, B.R.; Gayana, S.

2010-01-01

Full text: Generator is constructed on the principle of decay growth relationship between a long lived parent radionuclide and short lived daughter radionuclide. Difference in chemical properties of daughter and parent radionuclide helps in efficient separation of the two radionuclides. Aim and Objectives: The present study was designed to calculate the elution efficiency of the generator using the traditional formula based method and free web based software method. Materials and Methods: 99 Mo/ 99m Tc MON.TEK (Monrol, Gebze) generator and sterile 0.9% NaCl vial and vacuum vial in the lead shield were used for the elution. A new 99 Mo/ 99m Tc generator (calibrated activity 30GBq) calibrated for thursday was received on monday morning in our department. Generator was placed behind lead bricks in fume hood. The rubber plugs of both vacuum and 0.9% NaCl vial were wiped with 70% isopropyl alcohol swabs. Vacuum vial placed inside the lead shield was inserted in the vacuum position simultaneously 10 ml NaCl vial was inserted in the second slot. After 1-2 min vacuum vial was removed without moving the emptied 0.9%NaCl vial. The vacuum slot was covered with another sterile vial to maintain sterility. The RAC was measured in the calibrated dose calibrator (Capintec, 15 CRC). The elution efficiency was calculated theoretically and using free web based software (Apache Web server (www.apache.org) and PHP (www.php.net). Web site of the Italian Association of Nuclear Medicine and Molecular Imaging (www.aimn.it). Results: The mean elution efficiency calculated by theoretical method was 93.95% +0.61. The mean elution efficiency as calculated by the software was 92.85% + 0.89. There was no statistical difference in both the methods. Conclusion: The free web based software provides precise and reproducible results and thus saves time and mathematical calculation steps. This enables a rational use of available activity and also enabling a selection of the type and number of

Dissolution of ion exchange resin by hydrogen peroxide

International Nuclear Information System (INIS)

Lee, S.C.

1981-08-01

The resin dissolution process was conducted successfully in full-scale equipment at the SRL Semiworks. A solution containing 0.001M Fe 2+ , or Fe 3+ , and 3 vol % H 2 O 2 in 0.1M HNO 3 is sufficient to dissolve up to 40 vol % resin slurry (Dowex 50W-X8). Foaming and pressurization can be eliminated by maintaining the dissolution temperature below 99 0 C. The recommended dissolution temperature range is 85 to 90 0 C. Premixing hydrogen peroxide with all reactants will not create a safety hazard, but operating with a continual feed of hydrogen peroxide is recommended to control the dissolution rate. An air sparging rate of 1.0 to 1.5 scfm will provide sufficient mixing. Spent resin from chemical separation contains DTPA (diethylenetriaminepentaacetic acid) residue, and the resin must be washed with 0.1M NH 4 OH to remove excess DTPA before dissolution. Gamma irradiation of resin up to 4 kW-hr/L did not change the dissolution rate significantly

El impacto de las nuevas políticas de seguridad vial sobre la conducta de los conductores

Directory of Open Access Journals (Sweden)

Jordi Tena-Sánchez

2013-04-01

Full Text Available La evidencia empírica disponible señala de manera unánime que las nuevas políticas de tráfico y seguridad vial aplicadas en España desde 2004, y en particular la introducción del carné por puntos y la reforma del Código Penal, han tenido una fuerte incidencia positiva en la reducción de la siniestralidad. De dichos resultados se deriva que las nuevas políticas han tenido también un efecto positivo sobre la conducta de los conductores, de modo que ha sido esa mejora en la conducta al volante la que finalmente se ha traducido en una reducción de la siniestralidad. No obstante, hasta el momento, los investigadores han descuidado el análisis directo de los datos sobre cumplimiento. En el presente trabajo se analizan todos los datos disponibles que ofrecen información sobre el cumplimiento de la normativa de tráfico y seguridad vial.

Oxidation and dissolution of UO{sub 2} in bicarbonate media: Implications for the spent nuclear fuel oxidative dissolution mechanism

Energy Technology Data Exchange (ETDEWEB)

Gimenez, J. [Department of Chemical Engineering, Universitat Politecnica de Catalunya, Diagonal 647, 08028 Barcelona (Spain)]. E-mail: francisco.javier.gimenez@upc.edu; Clarens, F. [Department of Chemical Engineering, Universitat Politecnica de Catalunya, Diagonal 647, 08028 Barcelona (Spain); Casas, I. [Department of Chemical Engineering, Universitat Politecnica de Catalunya, Diagonal 647, 08028 Barcelona (Spain); Rovira, M. [CTM Centre Tecnologic, Avda. Bases de Manresa 1. 08240 Manresa (Spain); Pablo, J. de [Department of Chemical Engineering, Universitat Politecnica de Catalunya, Diagonal 647, 08028 Barcelona (Spain); Bruno, J. [Enresa-Enviros Environmental Science and Waste Management Chair, UPC, Jordi Girona 1-3 B2, 08034 Barcelona (Spain)

2005-10-15

The objective of this work is to study the UO{sub 2} oxidation by O{sub 2} and dissolution in bicarbonate media and to extrapolate the results obtained to improve the knowledge of the oxidative dissolution of spent nuclear fuel. The results obtained show that in the studied range the oxygen consumption rate is independent on the bicarbonate concentration while the UO{sub 2} dissolution rate does depend on. Besides, at 10{sup -4} mol dm{sup -3} bicarbonate concentration, the oxygen consumption rate is almost two orders of magnitude higher than the UO{sub 2} dissolution rate. These results suggest that at low bicarbonate concentration (<10{sup -2} mol dm{sup -3}) the alteration of the spent nuclear fuel cannot be directly derived from the measured uranium concentrations in solution. On the other hand, the study at low bicarbonate concentrations of the evolution of the UO{sub 2} surface at nanometric scale by means of the SFM technique shows that the difference between oxidation and dissolution rates is not due to the precipitation of a secondary solid phase on UO{sub 2}.

Frogging It: A poetic Analysis of Relationship Dissolution

Directory of Open Access Journals (Sweden)

Sandra L. Faulkner

2012-10-01

Full Text Available Often, themes in work and life intertwine; the author recognized that a cadre of poems she had written during the past several years were about relationship dissolution. The poems concerned romantic and friendship dissolution and the aspects of identity creation and loss this entails. The author presents the poems and makes an explicit connection to interpersonal relationship dissolution literature through the technique of poetic analysis. This analysis serves as an exemplar for how poetry as performative writing offers a valuable addition to interpersonal communication research through the poeticizing of relational dissolution as an everyday relational challenge.

El Sistema Vial Inca y los desafíos para su conservación en tiempos modernos

OpenAIRE

Ríos Canales, Moisés

2013-01-01

El Estado peruano, a través del Ministerio de Cultura, desarrolla dentro de su política cultural una estrategia para la identificación, protección, conservación y puesta en uso social del Sistema Vial Inca, el mayor monumento de la historia americana construida por el Estado Inca en el Siglo XV.

Uranium carbide dissolution in nitric solution: Sonication vs. silent conditions

International Nuclear Information System (INIS)

Virot, Matthieu; Szenknect, Stéphanie; Chave, Tony; Dacheux, Nicolas; Moisy, Philippe; Nikitenko, Sergey I.

2013-01-01

The dissolution of uranium carbide (UC) in nitric acid media is considered by means of power ultrasound (sonication) or magnetic stirring. The induction period required to initiate UC dissolution was found to be dramatically shortened when sonicating a 3 M nitric solution (Ar, 20 kHz, 18 W cm −2 , 20 °C). At higher acidity, magnetic stirring offers faster dissolution kinetics compared to sonication. Ultrasound-assisted UC dissolution is found to be passivated after ∼60% dissolution and remains incomplete whatever the acidity which is confirmed by ICP–AES, LECO and SEM–EDX analyses. In general, the kinetics of UC dissolution is linked to the in situ generation of nitrous acid in agreement with the general mechanism of UC dissolution; the nitrous acid formation is reported to be faster under ultrasound at low acidity due to the nitric acid sonolysis. The carbon balance shared between the gaseous, liquid, and solid phases is strongly influenced by the applied dissolution procedure and HNO 3 concentration

Uranium carbide dissolution in nitric solution: Sonication vs. silent conditions

Science.gov (United States)

Virot, Matthieu; Szenknect, Stéphanie; Chave, Tony; Dacheux, Nicolas; Moisy, Philippe; Nikitenko, Sergey I.

2013-10-01

The dissolution of uranium carbide (UC) in nitric acid media is considered by means of power ultrasound (sonication) or magnetic stirring. The induction period required to initiate UC dissolution was found to be dramatically shortened when sonicating a 3 M nitric solution (Ar, 20 kHz, 18 W cm-2, 20 °C). At higher acidity, magnetic stirring offers faster dissolution kinetics compared to sonication. Ultrasound-assisted UC dissolution is found to be passivated after ∼60% dissolution and remains incomplete whatever the acidity which is confirmed by ICP-AES, LECO and SEM-EDX analyses. In general, the kinetics of UC dissolution is linked to the in situ generation of nitrous acid in agreement with the general mechanism of UC dissolution; the nitrous acid formation is reported to be faster under ultrasound at low acidity due to the nitric acid sonolysis. The carbon balance shared between the gaseous, liquid, and solid phases is strongly influenced by the applied dissolution procedure and HNO3 concentration.

TANK 12 SLUDGE CHARACTERIZATION AND ALUMINUM DISSOLUTION DEMONSTRATION

International Nuclear Information System (INIS)

Reboul, S.; Hay, Michael; Zeigler, Kristine; Stone, Michael

2009-01-01

A 3-L sludge slurry sample from Tank 12 was characterized and then processed through an aluminum dissolution demonstration. The dominant constituent of the sludge was found to be aluminum in the form of boehmite. The iron content was minor, about one-tenth that of the aluminum. The salt content of the supernatant was relatively high, with a sodium concentration of ∼7 M. Due to these characteristics, the yield stress and plastic viscosity of the unprocessed slurry were relatively high (19 Pa and 27 cP), and the settling rate of the sludge was relatively low (∼20% settling over a two and a half week period). Prior to performing aluminum dissolution, plutonium and gadolinium were added to the slurry to simulate receipt of plutonium waste from H-Canyon. Aluminum dissolution was performed over a 26 day period at a temperature of 65 C. Approximately 60% of the insoluble aluminum dissolved during the demonstration, with the rate of dissolution slowing significantly by the end of the demonstration period. In contrast, approximately 20% of the plutonium and less than 1% of the gadolinium partitioned to the liquid phase. However, about a third of the liquid phase plutonium became solubilized prior to the dissolution period, when the H-Canyon plutonium/gadolinium simulant was added to the Tank 12 slurry. Quantification of iron dissolution was less clear, but appeared to be on the order of 1% based on the majority of data (a minor portion of the data suggested iron dissolution could be as high as 10%). The yield stress of the post-dissolution slurry (2.5 Pa) was an order of magnitude lower than the initial slurry, due most likely to the reduced insoluble solids content caused by aluminum dissolution. In contrast, the plastic viscosity remained unchanged (27 cP). The settling rate of the post-dissolution slurry was higher than the initial slurry, but still relatively low compared to settling of typical high iron content/low salt content sludges. Approximately 40% of the

Dissolution and transport of plutonium from oxide particles in soils

International Nuclear Information System (INIS)

Brown, D.A.

1978-01-01

This report contains a summary of methods and data on plutonium dissolution and movement in four soils, plus a copy of a manuscript describing the automatic sample changer for alpha radiation detection which has been submitted for publication

Dissolution patterns of biocompatible glasses in 2-amino-2-hydroxymethyl-propane-1,3-diol (Tris) buffer.

Science.gov (United States)

Fagerlund, S; Hupa, L; Hupa, M

2013-02-01

A continuous flow measurement system with sensitive on-line ion analysis has been applied to study the initial dissolution behaviour of biocompatible glasses in Tris. Altogether 16 glasses with widely varying compositions were studied. The measurement system allowed for quantitative determination of the time-dependent rates of dissolution of sodium, potassium, calcium, magnesium, silicon and phosphorus during the first 10-15 min in contact with Tris solution. The dissolution rates of the different ions showed significant glass to glass variations, but all glasses studied showed one of four distinct dissolution patterns. The ion dissolution rates after an exposure of 1000 s, expressed as the normalized surface-specific mass loss rates, were compared with the in vitro and in vivo reactivity of the glasses as predicted by models in the literature. The results showed a clear correlation between the dissolution rates of the glasses in Tris and their reactivity as measured by other different methods. Consequently, the measured short-term dissolution patterns could be used to determine which glasses are suitable as bioactive, biodegradable, or inert biomaterials for medical devices. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Dissolution behaviour of silicon nitride coatings for joint replacements

Energy Technology Data Exchange (ETDEWEB)

Pettersson, Maria [Materials in Medicine Group, Div. of Applied Materials Science, Dept. of Engineering Sciences, Uppsala University, Uppsala (Sweden); Bryant, Michael [Institute of Functional Surfaces (iFS), School of Mechanical Engineering, University of Leeds, Leeds (United Kingdom); Schmidt, Susann [Thin Film Physics, Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping (Sweden); Engqvist, Håkan [Materials in Medicine Group, Div. of Applied Materials Science, Dept. of Engineering Sciences, Uppsala University, Uppsala (Sweden); Hall, Richard M. [Institute of Medical and Biological Engineering (iMBE), School of Mechanical Engineering, University of Leeds, Leeds (United Kingdom); Neville, Anne [Institute of Functional Surfaces (iFS), School of Mechanical Engineering, University of Leeds, Leeds (United Kingdom); Persson, Cecilia, E-mail: cecilia.persson@angstrom.uu.se [Materials in Medicine Group, Div. of Applied Materials Science, Dept. of Engineering Sciences, Uppsala University, Uppsala (Sweden)

2016-05-01

In this study, the dissolution rate of SiN{sub x} coatings was investigated as a function of coating composition, in comparison to a cobalt chromium molybdenum alloy (CoCrMo) reference. SiN{sub x} coatings with N/Si ratios of 0.3, 0.8 and 1.1 were investigated. Electrochemical measurements were complemented with solution (inductively coupled plasma techniques) and surface analysis (vertical scanning interferometry and x-ray photoelectron spectroscopy). The dissolution rate of the SiN{sub x} coatings was evaluated to 0.2–1.4 nm/day, with a trend of lower dissolution rate with higher N/Si atomic ratio in the coating. The dissolution rates of the coatings were similar to or lower than that of CoCrMo (0.7–1.2 nm/day). The highest nitrogen containing coating showed mainly Si–N bonds in the bulk as well as at the surface and in the dissolution area. The lower nitrogen containing coatings showed Si–N and/or Si–Si bonds in the bulk and an increased formation of Si–O bonds at the surface as well as in the dissolution area. The SiN{sub x} coatings reduced the metal ion release from the substrate. The possibility to tune the dissolution rate and the ability to prevent release of metal ions encourage further studies on SiN{sub x} coatings for joint replacements. - Graphical abstract: Dissolution rates of SiN{sub 0.3}, SiN{sub 0.8}, and SiN{sub 1.1} coatings on CoCrMo compared to uncoated CoCrMo. Dissolution rates were obtained from i) electrochemical measurements of I{sub corr}, ii) the step height between covered and solution-exposed surfaces, measured using VSI, and iii) the ion concentration in the solution, measured with ICP. - Highlights: • The dissolution of SiN{sub x} coatings was investigated in comparison to (bulk) CoCrMo. • The coatings gave a lower or similar dissolution rate to CoCrMo, of 0.2–1.2 nm/day. • An increased nitrogen content in the coatings gave lower dissolution rates. • SiN{sub x} coatings on CoCrMo reduced the metal ion release

Leaching of plastic polymers by plastic vials used for storing homoeopathic medicines: A preliminary study

Directory of Open Access Journals (Sweden)

Neeraj Gupta

2014-01-01

Full Text Available Background: In Homoeopathy, plastic containers/vials are used for the storing/dispensing of ethanol-based medicines instead of glass. Various studies have suggested that plastic components that leach out in stored substances tend to cause contamination and may produce adverse effects in living systems. The present study was aimed to find out chemical composition and leaching behaviour of commonly used plastic vials (PVs if any during the storage of ethanol-based homoeopathic medicines in optimal environment. Material and Methods: The experiments were conducted on two sample sets of PVs. Chemical properties of PV were assessed by Fourier Transform Infrared Attenuated Total Reflectance (FTIR-ATR spectroscopy. PV were cut separately [sample-1 (S-1 and sample-2 (S-2] and immersed in Homoeopathic Grade Ethanol (HGE in conical flask and stored for 7 days at ambient temperature (25° ± 5C with constant rotary shaking. After 7 days, S-1 and S-2 of PV in Homoeopathic Grade Ethanol (HGE were decanted and filtered. Aliquots (A1 and A2 were analysed by proton nuclear magnetic resonance spectroscopy (H 1 NMR. The spectral graph obtained by FTIR-ATR spectroscopy for PV compositions and spectral graph obtained by H 1 NMR spectroscopy for PV ethanol aliquots were examined for PVs material and PV leaching effect in HGE. Results: FTIR-ATR spectra showed that PV are made up of two types of polyolefin′s compounds i.e. Low Density Polyethylene (LDPE and Linear Low Density Polyethylene (LLDPE. Aliquots of PV in HGE showed the presence benzophenone and its methyl derivative, heat and light stabiliser (2, 2, 6, 6-tetramethylpiperidine and amino derivative, antioxidant (4, 4′- thiobis and 2-tertbutyl-5-methylphenol and plasticizer bis 2-Diethylhexyl phthalate (DEHP or Dioctyl phthalate (DOP. Results of study suggest that PVs leach out plastic polymers in HGE. Conclusion: This preliminary experiment suggests that it is not safe to use LDPE/LLDPE plastic for storing

Development of ammonium bifluoride fusion method for rapid dissolution of trinitite samples and analysis by ICP-MS

International Nuclear Information System (INIS)

Hubley, Nickolas; Brown IV, J.W.N.; Guthrie, James; Brockman, J.D.; Robertson, J.D.; University of Missouri, Columbia, MO

2016-01-01

Field deployable dissolution techniques are needed to decrease response time following a nuclear event. This study tested the capability of NH 4 HF 2 fusion to dissolve trinitite. Dissolution of trinitite by NH 4 HF 2 fusion was compared to conventional microwave digestion. Following digestion, trace elements were measured using ICPMS. This work demonstrates that low temperature fusion with NH 4 HF 2 is capable of dissolving trinitite samples. The low purity of the NH 4 HF 2 resulted in a higher limit of detection for several elements when compared to microwave digestion with high purity acids. (author)

Catalysed electrolytic metal oxide dissolution processes

International Nuclear Information System (INIS)

Machuron-Mandard, X.

1994-01-01

The hydrometallurgical processes designed for recovering valuable metals from mineral ores as well as industrial wastes usually require preliminary dissolution of inorganic compounds in aqueous media before extraction and purification steps. Unfortunately, most of the minerals concerned hardly or slowly dissolve in acidic or basic solutions. Metallic oxides, sulfides and silicates are among the materials most difficult to dissolve in aqueous solutions. They are also among the main minerals containing valuable metals. The redox properties of such materials sometimes permit to improve their dissolution by adding oxidizing or reducing species to the leaching solution, which leads to an increase in the dissolution rate. Moreover, limited amounts of redox promoters are required if the redox agent is regenerated continuously thanks to an electrochemical device. Nuclear applications of such concepts have been suggested since the dissolution of many actinide compounds (e.g., UO 2 , AmO 2 , PuC, PuN,...) is mainly based on redox reactions. In the 1980s, improvements of the plutonium dioxide dissolution process have been proposed on the basis of oxidation-reduction principles, which led a few years later to the design of industrial facilities (e.g., at Marcoule or at the french reprocessing plant of La Hague). General concepts and well-established results obtained in France at the Atomic Energy Commission (''Commissariat a l'Energie Atomique'') will be presented and will illustrate applications to industrial as well as analytical problems. (author)

The Dissolution Behavior of Borosilicate Glasses in Far-From Equilibrium Conditions

Energy Technology Data Exchange (ETDEWEB)

Neeway, James J.; Rieke, Peter C.; Parruzot, Benjamin PG; Ryan, Joseph V.; Asmussen, Robert M.

2018-02-10

In far-from-equilibrium conditions, the dissolution of borosilicate glasses used to immobilize nuclear waste is known to be a function of both temperature and pH. The aim of this paper is to study effects of these variables on three model waste glasses (SON68, ISG, AFCI). To do this, experiments were conducted at temperatures of 23, 40, 70, and 90 °C and pH(RT) values of 9, 10, 11, and 12 with the single-pass flow-through (SPFT) test method. The results from these tests were then used to parameterize a kinetic rate model based on transition state theory. Both the absolute dissolution rates and the rate model parameters are compared with previous results. Discrepancies in the absolute dissolution rates as compared to those obtained using other test methods are discussed. Rate model parameters for the three glasses studied here are nearly equivalent within error and in relative agreement with previous studies. The results were analyzed with a linear multivariate regression (LMR) and a nonlinear multivariate regression performed with the use of the Glass Corrosion Modeling Tool (GCMT), which is capable of providing a robust uncertainty analysis. This robust analysis highlights the high degree of correlation of various parameters in the kinetic rate model. As more data are obtained on borosilicate glasses with varying compositions, the effect of glass composition on the rate parameter values could possibly be obtained. This would allow for the possibility of predicting the forward dissolution rate of glass based solely on composition

[Process monitoring of dissolution of valsartan and hydrochlorothiazide tablets by fiber-chemical sensor assisted by mathematical separation model of linear equations].

Science.gov (United States)

Ding, Hai-Yan; Li, Gai-Ru; Yu, Ying-Ge; Guo, Wei; Zhi, Ling; Li, Xin-Xia

2014-04-01

A method for on-line monitoring the dissolution of Valsartan and hydrochlorothiazide tablets assisted by mathematical separation model of linear equations was established. UV spectrums of valsartan and hydrochlorothiazide were overlapping completely at the maximum absorption wavelength respectively. According to the Beer-Lambert principle of absorbance additivity, the absorptivity of Valsartan and hydrochlorothiazide was determined at the maximum absorption wavelength, and the dissolubility of Valsartan and hydrochlorothiazide tablets was detected by fiber-optic dissolution test (FODT) assisted by the mathematical separation model of linear equations and compared with the HPLC method. Results show that two ingredients were real-time determined simultaneously in given medium. There was no significant difference for FODT compared with HPLC (p > 0.05). Due to the dissolution behavior consistency, the preparation process of different batches was stable and with good uniformity. The dissolution curves of valsartan were faster and higher than hydrochlorothiazide. The dissolutions at 30 min of Valsartan and hydrochlorothiazide were concordant with US Pharmacopoeia. It was concluded that fiber-optic dissolution test system assisted by the mathematical separation model of linear equations that can detect the dissolubility of Valsartan and hydrochlorothiazide simultaneously, and get dissolution profiles and overall data, which can directly reflect the dissolution speed at each time. It can provide the basis for establishing standards of the drug. Compared to HPLC method with one-point data, there are obvious advantages to evaluate and analyze quality of sampling drug by FODT.

Effect of alteration phase formation on the glass dissolution rate

International Nuclear Information System (INIS)

Ebert, W.L.

1997-01-01

The dissolution rates of many glasses have been observed to increase upon the formation of certain alteration phases. While simulations have predicted the accelerating effect of formation of certain phases, the phases predicted to form in computer simulations are usually different than those observed to form in experiments. This is because kinetically favored phases form first in experiments, while simulations predict the thermodynamically favored phases. Static dissolution tests with crushed glass have been used to measure the glass dissolution rate after alteration phases form. Because glass dissolution rates are calculated on a per area basis, an important effect in tests conducted with crushed glass is the decrease in the surface area of glass that is available for reaction as the glass dissolves. This loss of surface area must be taken into account when calculating the dissolution rate. The phases that form and their effect on the dissolution rate are probably related to the glass composition. The impact of phase formation on the glass dissolution rate also varies according to the solubility products of the alteration phases and how the orthocilicic acid activity is affected. Insight into the relationship between the glass dissolution rate, solution chemistry and alteration phase formation is provided by the results of accelerated dissolution tests

Effect of alteration phase formation on the glass dissolution rate

Energy Technology Data Exchange (ETDEWEB)

Ebert, W L [Argonne National Laboratory, Chemical Technology Div. (United States)

1997-07-01

The dissolution rates of many glasses have been observed to increase upon the formation of certain alteration phases. While simulations have predicted the accelerating effect of formation of certain phases, the phases predicted to form in computer simulations are usually different than those observed to form in experiments. This is because kinetically favored phases form first in experiments, while simulations predict the thermodynamically favored phases. Static dissolution tests with crushed glass have been used to measure the glass dissolution rate after alteration phases form. Because glass dissolution rates are calculated on a per area basis, an important effect in tests conducted with crushed glass is the decrease in the surface area of glass that is available for reaction as the glass dissolves. This loss of surface area must be taken into account when calculating the dissolution rate. The phases that form and their effect on the dissolution rate are probably related to the glass composition. The impact of phase formation on the glass dissolution rate also varies according to the solubility products of the alteration phases and how the orthocilicic acid activity is affected. Insight into the relationship between the glass dissolution rate, solution chemistry and alteration phase formation is provided by the results of accelerated dissolution tests.

DISSOLUTION OF ZIRCONIUM AND ALLOYS THEREFOR

Science.gov (United States)

Swanson, J.L.

1961-07-11

The dissolution of zirconium cladding in a water solution of ammonium fluoride and ammonium nitrate is described. The method finds particular utility in processing spent fuel elements for nuclear reactors. The zirconium cladding is first dissolved in a water solution of ammonium fluoride and ammonium nitrate; insoluble uranium and plutonium fiuorides formed by attack of the solvent on the fuel materiai of the fuel element are then separated from the solution, and the fuel materiai is dissolved in another solution.

Artificial Leaks in Container Closure Integrity Testing: Nonlinear Finite Element Simulation of Aperture Size Originated by a Copper Wire Sandwiched between the Stopper and the Glass Vial.

Science.gov (United States)

Nieto, Alejandra; Roehl, Holger; Brown, Helen; Adler, Michael; Chalus, Pascal; Mahler, Hanns-Christian

2016-01-01

Container closure integrity (CCI) testing is required by different regulatory authorities in order to provide assurance of tightness of the container closure system against possible contamination, for example, by microorganisms. Microbial ingress CCI testing is performed by incubation of the container closure system with microorganisms under specified testing conditions. Physical CCI uses surrogate endpoints, such as coloration by dye solution ingress or gas flow (helium leakage testing). In order to correlate microbial CCI and physical CCI test methods and to evaluate the methods' capability to detect a given leak, artificial leaks are being introduced into the container closure system in a variety of different ways. In our study, artificial leaks were generated using inserted copper wires between the glass vial opening and rubber stopper. However, the insertion of copper wires introduces leaks of unknown size and shape. With nonlinear finite element simulations, the aperture size between the rubber stopper and the glass vial was calculated, depending on wire diameter and capping force. The dependency of the aperture size on the copper wire diameter was quadratic. With the data obtained, we were able to calculate the leak size and model leak shape. Our results suggest that the size as well as the shape of the artificial leaks should be taken into account when evaluating critical leak sizes, as flow rate does not, independently, correlate to hole size. Capping force also affected leak size. An increase in the capping force from 30 to 70 N resulted in a reduction of the aperture (leak size) by approximately 50% for all wire diameters. From 30 to 50 N, the reduction was approximately 33%. Container closure integrity (CCI) testing is required by different regulatory authorities in order to provide assurance of tightness of the container closure system against contamination, for example, by microorganisms. Microbial ingress CCI testing is performed by incubation of the

Chemical Dissolution of Simulant FCA Cladding and Plates

Energy Technology Data Exchange (ETDEWEB)

Daniel, G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Pierce, R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); O' Rourke, P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-11-08

The Savannah River Site (SRS) has received some fast critical assembly (FCA) fuel from the Japan Atomic Energy Agency (JAEA) for disposition. Among the JAEA FCA fuel are approximately 7090 rectangular Stainless Steel clad fuel elements. Each element has an internal Pu-10.6Al alloy metal wafer. The thickness of each element is either 1/16 inch or 1/32 inch. The dimensions of each element ranges from 2 inches x 1 inch to 2 inches x 4 inches. This report discusses the potential chemical dissolution of the FCA clad material or stainless steel. This technology uses nitric acid-potassium fluoride (HNO₃-KF) flowsheets of H-Canyon to dissolve the FCA elements from a rack of materials. Historically, dissolution flowsheets have aimed to maximize Pu dissolution rates while minimizing stainless steel dissolution (corrosion) rates. Because the FCA cladding is made of stainless steel, this work sought to accelerate stainless steel dissolution.

Montmorillonite dissolution kinetics: Experimental and reactive transport modeling interpretation

Science.gov (United States)

Cappelli, Chiara; Yokoyama, Shingo; Cama, Jordi; Huertas, F. Javier

2018-04-01

The dissolution kinetics of K-montmorillonite was studied at 25 °C, acidic pH (2-4) and 0.01 M ionic strength by means of well-mixed flow-through experiments. The variations of Si, Al and Mg over time resulted in high releases of Si and Mg and Al deficit, which yielded long periods of incongruent dissolution before reaching stoichiometric steady state. This behavior was caused by simultaneous dissolution of nanoparticles and cation exchange between the interlayer K and released Ca, Mg and Al and H. Since Si was only involved in the dissolution reaction, it was used to calculate steady-state dissolution rates, RSi, over a wide solution saturation state (ΔGr ranged from -5 to -40 kcal mol-1). The effects of pH and the degree of undersaturation (ΔGr) on the K-montmorillonite dissolution rate were determined using RSi. Employing dissolution rates farthest from equilibrium, the catalytic pH effect on the K-montmorillonite dissolution rate was expressed as Rdiss = k·aH0.56±0.05 whereas using all dissolution rates, the ΔGr effect was expressed as a non-linear f(ΔGr) function Rdiss = k · [1 - exp(-3.8 × 10-4 · (|ΔGr|/RT)2.13)] The functionality of this expression is similar to the equations reported for dissolution of Na-montmorillonite at pH 3 and 50 °C (Metz, 2001) and Na-K-Ca-montmorillonite at pH 9 and 80 °C (Cama et al., 2000; Marty et al., 2011), which lends support to the use of a single f(ΔGr) term to calculate the rate over the pH range 0-14. Thus, we propose a rate law that also accounts for the effect of pOH and temperature by using the pOH-rate dependence and the apparent activation energy proposed by Rozalén et al. (2008) and Amram and Ganor (2005), respectively, and normalizing the dissolution rate constant with the edge surface area of the K-montmorillonite. 1D reactive transport simulations of the experimental data were performed using the Crunchflow code (Steefel et al., 2015) to quantitatively interpret the evolution of the released cations

Chrysotile dissolution rates: Implications for carbon sequestration

International Nuclear Information System (INIS)

Thom, James G.M.; Dipple, Gregory M.; Power, Ian M.; Harrison, Anna L.

2013-01-01

Highlights: • Uncertainties in serpentine dissolution kinetics hinder carbon sequestration models. • A pH dependent, far from equilibrium dissolution rate law for chrysotile. • F chrysotile (mol/m 2 /s) = 10 −0.21pH−10.57 at 22 °C over pH 2–10. • Laboratory dissolution rates consistent with mine waste weathering observations. • Potential for carbon sequestration in mine tailings and aquifers is assessed. - Abstract: Serpentine minerals (e.g., chrysotile) are a potentially important medium for sequestration of CO 2 via carbonation reactions. The goals of this study are to report a steady-state, far from equilibrium chrysotile dissolution rate law and to better define what role serpentine dissolution kinetics will have in constraining rates of carbon sequestration via serpentine carbonation. The steady-state dissolution rate of chrysotile in 0.1 m NaCl solutions was measured at 22 °C and pH ranging from 2 to 8. Dissolution experiments were performed in a continuously stirred flow-through reactor with the input solutions pre-equilibrated with atmospheric CO 2 . Both Mg and Si steady-state fluxes from the chrysotile surface, and the overall chrysotile flux were regressed and the following empirical relationships were obtained: F Mg =-0.22pH-10.02;F Si =-0.19pH-10.37;F chrysotile =-0.21pH-10.57 where F Mg , F Si , and F chrysotile are the log 10 Mg, Si, and molar chrysotile fluxes in mol/m 2 /s, respectively. Element fluxes were used in reaction-path calculations to constrain the rate of CO 2 sequestration in two geological environments that have been proposed as potential sinks for anthropogenic CO 2 . Carbon sequestration in chrysotile tailings at 10 °C is approximately an order of magnitude faster than carbon sequestration in a serpentinite-hosted aquifer at 60 °C on a per kilogram of water basis. A serpentinite-hosted aquifer, however, provides a larger sequestration capacity. The chrysotile dissolution rate law determined in this study has

Solubility and dissolution enhancement of flurbiprofen by solid dispersion using hydrophilic carriers

Directory of Open Access Journals (Sweden)

Bhaskar Daravath

2018-05-01

Full Text Available ABSTRACT The intent of the current work is to study the effect of polyethylene glycol 8000 and polyethylene glycol 10000 as hydrophilic carriers on dissolution behaviour of flurbiprofen. In the present study, solvent evaporation method was used to prepare flurbiprofen solid dispersions and evaluated for physico-chemical properties, drug-carrier compatibility studies and dissolution behaviour of drug. Solubility studies showed more solubility in higher pH values and formulations SD4 and SD8 were selected to prepare the fast dissolving tablets. FTIR and DSC study showed no interaction and drug was dispersed molecularly in hydrophilic carrier. XRD studies revealed that there was change in the crystallinity of the drug. The results of In vitro studies showed SD8 formulation confer significant improvement (p<0.05 in drug release, Q20 was 99.08±1.35% compared to conventional and marketed tablets (47.31±0.74% and 56.86±1.91%. The mean dissolution time (MDT was reduced to 8.79 min compared to conventional and marketed tablets (25.76 and 22.22 min. indicating faster drug release. The DE (% dissolution efficiency was increased by 2.5 folds (61.63% compared to conventional tablets (23.71%. From the results, it is evident that polyethylene glycol solid dispersions in less carrier ratio may enhance the solubility and there by improve the dissolution rate of flurbiprofen.

Improvement in Dissolution of Cotton Pulp with Ionic liquid by the Electron Beam Treatment

International Nuclear Information System (INIS)

Lee, Won Sil; Jung, Wong Gi; Sung, Yong Joo

2013-01-01

Electron beam treatment was applied for improving dissolution of cotton pulp with ionic liquids. Two ionic liquids, 1-allyl-3-methylimidazolium chloride ([Amim]Cl]: AC) and 1,3-dimethylimidzolium methlphosphite ([Dmim][(MeO)(H)PO2]: Me) were used for this experiment. Treatment with electron beams up to dose of 400 kGy resulted in the increase of hot water extract and alkali extract of cotton pulp and the great reduction in the molecular weight of cellulose. For the dissolution of cotton pulp with two ionic liquids, the electron beam treated samples showed faster dissolution. The dissolved cellulose with Me ionic liquid were regenerated with Acetonitrile and the structure of regenerated cellulose showed distinct difference depending on the electron beam treatment. Those results provide the electron beam pre-treatment could be applied as an energy efficient and environmentally benign method to increase the dissolution of cotton pulp with ionic liquids

Waste form dissolution in bedded salt

International Nuclear Information System (INIS)

Kaufman, A.M.

1980-01-01

A model was devised for waste dissolution in bedded salt, a hydrologically tight medium. For a typical Spent UnReprocessed Fuel (SURF) emplacement, the dissolution rate wll be diffusion limited and will rise to a steady state value after t/sub eq/ approx. = 250 (1+(1-epsilon 0 ) K/sub D//epsilon 0 ) (years) epsilon 0 is the overpack porosity and K/sub d/ is the overpack sorption coefficient. The steady state dissolution rate itself is dominated by the solubility of UO 2 . Steady state rates between 5 x 10 -5 and .5 (g/year) are achievable by SURF emplacements in bedded salt without overpack, and rates between 5 x 10 -7 and 5 x 10 -3 (g/year) with an overpack having porosity of 10 -2

Emotional and Cognitive Coping in Relationship Dissolution

Science.gov (United States)

Wrape, Elizabeth R.; Jenkins, Sharon Rae; Callahan, Jennifer L.; Nowlin, Rachel B.

2016-01-01

Dissolution of a romantic relationship can adversely affect functioning among college students and represents one primary reason for seeking campus counseling. This study examined the associations among common coping strategies and distress following relationship dissolution. Avoidance and repetitive negative thinking (RNT) were significantly…

CALCIUM CARBONATE DISSOLUTION RATE IN LIMESTONE CONTACTORS

Science.gov (United States)

The rate of carbonate mineral dissolution from limestone was studied using a rotating disk apparatus and samples of limestone of varied composition. The purpose of this study was to determine the effect of limestone composition on the kinetics of carbonate mineral dissolution. Th...

Capsule shell material impacts the in vitro disintegration and dissolution behaviour of a green tea extract☆

Science.gov (United States)

Glube, Natalie; Moos, Lea von; Duchateau, Guus

2013-01-01

Purpose In vitro disintegration and dissolution are routine methods used to assess the performance and quality of oral dosage forms. The purpose of the current work was to determine the potential for interaction between capsule shell material and a green tea extract and the impact it can have on the release. Methods A green tea extract was formulated into simple powder-in-capsule formulations of which the capsule shell material was either of gelatin or HPMC origin. The disintegration times were determined together with the dissolution profiles in compendial and biorelevant media. Results All formulations disintegrated within 30 min, meeting the USP criteria for botanical formulations. An immediate release dissolution profile was achieved for gelatin capsules in all media but not for the specified HPMC formulations. Dissolution release was especially impaired for HPMCgell at pH 1.2 and for both HPMC formulations in FeSSIF media suggesting the potential for food interactions. Conclusions The delayed release from studied HPMC capsule materials is likely attributed to an interaction between the catechins, the major constituents of the green tea extract, and the capsule shell material. An assessment of in vitro dissolution is recommended prior to the release of a dietary supplement or clinical trial investigational product to ensure efficacy. PMID:25755998

Dissolution mechanisms of CO2 hydrate droplets in deep seawaters

International Nuclear Information System (INIS)

Gabitto, Jorge; Tsouris, Costas

2006-01-01

Carbon dioxide dissolution at intermediate ocean depths was studied using physical and mass transfer models. Particle density and hydrate layer thickness were determined using existing field data. Pseudo-homogeneous and heterogeneous mass transfer models were proposed to study the dissolution process. Pseudo-homogeneous models do not seem to represent the dissolution process well. Although heterogeneous models interpret the physical behavior better, unresolved issues related to hydrate dissolution still remain. For example, solid hydrate forms on one side of the hydrate film while it dissolves on the other. Dissolution is a complex process that comprises at least two sequential steps. The global process is controlled by mass transfer inside the hydrate layer or by a dissolution reaction at the hydrate-water interface

Quantification of the resist dissolution process: an in situ analysis using high speed atomic force microscopy

Science.gov (United States)

Santillan, Julius Joseph; Shichiri, Motoharu; Itani, Toshiro

2016-03-01

This work focuses on the application of a high speed atomic force microscope (HS-AFM) for the in situ visualization / quantification of the resist dissolution process. This technique, as reported in the past, has provided useful pointers on the formation of resist patterns during dissolution. This paper discusses about an investigation made on the quantification of what we refer to as "dissolution unit size" or the basic units of patterning material dissolution. This was done through the establishment of an originally developed analysis method which extracts the difference between two succeeding temporal states of the material film surface (images) to indicate the amount of change occurring in the material film at a specific span of time. Preliminary experiments with actual patterning materials were done using a positive-tone EUV model resist composed only of polyhydroxystyrene (PHS)-based polymer with a molecular weight of 2,500 and a polydispersity index of 1.2. In the absence of a protecting group, the material was utilized at a 50nm film thickness with post application bake of 90°C/60s. The resulting film is soluble in the alkali-based developer even without exposure. Results have shown that the dissolution components (dissolution unit size) of the PHS-based material are not of fixed size. Instead, it was found that aside from one constantly dissolving unit size, another, much larger dissolution unit size trend also occurs during material dissolution. The presence of this larger dissolution unit size suggests an occurrence of "polymer clustering". Such polymer clustering was not significantly present during the initial stages of dissolution (near the original film surface) but becomes more persistently obvious after the dissolution process reaches a certain film thickness below the initial surface.

Aluminium fractionation of European volcanic soils by selective dissolution techniques

NARCIS (Netherlands)

Garcia-Rodeja, E.; Novoa, J.C.; Pontevedra, X.; Martinez-Cortizas, A.; Buurman, P.

2004-01-01

Several selective dissolution methods were used to differentiate Al forms in 12 soils formed from volcanic materials (64 andic, vitric and organic horizons) in Iceland, Azores (Portugal), Tenerife (Spain) and Italy. The soils differ in many properties because of differences in parent materials,

Dissolution Threats and Legislative Bargaining

DEFF Research Database (Denmark)

Becher, Michael; Christiansen, Flemming Juul

2015-01-01

Chief executives in many parliamentary democracies have the power to dissolve the legislature. Despite a well-developed literature on the endogenous timing of parliamentary elections, political scientists know remarkably little about the strategic use of dissolution power to influence policymaking....... To address this gap, we propose and empirically evaluate a theoretical model of legislative bargaining in the shadow of executive dissolution power. The model implies that the chief executive's public support and legislative strength, as well as the time until the next constitutionally mandated election...

Sodium tetraphenylborate solubility and dissolution rates

International Nuclear Information System (INIS)

Barnes, M.J.; Peterson, R.A.; Swingle, R.F.; Reeves, C.T.

1995-01-01

The rate of solid sodium tetraphenylborate (NaTPB) dissolution in In-Tank Precipitation salt solutions has been experimentally determined. The data indicates that the dissolution rate of solid NaTPB is a minor contributor the lag time experienced in the 1983 Salt Decontamination Demonstration Test and should not be considered as the rate determining step. Current analytical models for predicting the time to reach the composite lower flammability limit assume that the lag time is not more than 6 hours, and the data supports this assumption (i.e., dissolution by itself requires much less than 6 hours). The data suggests that another step--such as mass transport, the reaction of a benzene precursor or the mixing behavior--is the rate determining factor for benzene release to the vapor space in Tank 48H. In addition, preliminary results from this program show that the degree of agitation employed is not a significant parameter in determining the rate of NaTPB dissolution. As a result of this study, an improved equation for predicting equilibrium tetraphenylborate solubility with respect to temperature and sodium ion concentration has been determined

Mesoporous Silica Molecular Sieve based Nanocarriers: Transpiring Drug Dissolution Research.

Science.gov (United States)

Pattnaik, Satyanarayan; Pathak, Kamla

2017-01-01

Improvement of oral bioavailability through enhancement of dissolution for poorly soluble drugs has been a very promising approach. Recently, mesoporous silica based molecular sieves have demonstrated excellent properties to enhance the dissolution velocity of poorly water-soluble drugs. Current research in this area is focused on investigating the factors influencing the drug release from these carriers, the kinetics of drug release and manufacturing approaches to scale-up production for commercial manufacture. This comprehensive review provides an overview of different methods adopted for synthesis of mesoporous materials, influence of processing factors on properties of these materials and drug loading methods. The drug release kinetics from mesoporous silica systems, the manufacturability and stability of these formulations are reviewed. Finally, the safety and biocompatibility issues related to these silica based materials are discussed. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Dissolution of covalent adaptable network polymers in organic solvent

Science.gov (United States)

Yu, Kai; Yang, Hua; Dao, Binh H.; Shi, Qian; Yakacki, Christopher M.

2017-12-01

It was recently reported that thermosetting polymers can be fully dissolved in a proper organic solvent utilizing a bond-exchange reaction (BER), where small molecules diffuse into the polymer, break the long polymer chains into short segments, and eventually dissolve the network when sufficient solvent is provided. The solvent-assisted dissolution approach was applied to fully recycle thermosets and their fiber composites. This paper presents the first multi-scale modeling framework to predict the dissolution kinetics and mechanics of thermosets in organic solvent. The model connects the micro-scale network dynamics with macro-scale material properties: in the micro-scale, a model is developed based on the kinetics of BERs to describe the cleavage rate of polymer chains and evolution of chain segment length during the dissolution. The micro-scale model is then fed into a continuum-level model with considerations of the transportation of solvent molecules and chain segments in the system. The model shows good prediction on conversion rate of functional groups, degradation of network mechanical properties, and dissolution rate of thermosets during the dissolution. It identifies the underlying kinetic factors governing the dissolution process, and reveals the influence of different material and processing variables on the dissolution process, such as time, temperature, catalyst concentration, and chain length between cross-links.

Status report on dissolution model development

International Nuclear Information System (INIS)

Jackson, D.D.

1983-07-01

The computer program PROTOCOL models the dissolution reactions of chemical species in water. It is being developed particularly to study the dissolution of proposed nuclear waste forms and related phases. Experimentally derived leaching rate functions are coupled to thermochemical equilibrium calculations and water flow rates. The program has been developed over a period of years. This report describes improvements that have been done in the past year

8 Dissolution Kinetics

African Journals Online (AJOL)

user

Experiments measuring the dissolution rates of stilbite (NaCa [Al Si O ].14H O) in pH-buffered ... The rate law was established as R = k (a ) , where k is ... crystalline hydrated aluminosilicate minerals ..... from the crushing process, thin edges or.

Dissolution studies of synthetic soddyite and uranophane

International Nuclear Information System (INIS)

Casas, I.; Perez, I.; Torrero, E.; Bruno, J.; Cera, E.; Duro, L.

1997-09-01

The dissolution of synthetically obtained soddyite and uranophane has been studied in solutions of low ionic strength. These are the likely final phases of the oxidative alternation pathway of uranium dioxide. The thermodynamic and kinetic dissolution properties of these phases have been determined at different bicarbonate concentrations. The solubilities determined in the experiments with soddyite correspond fairly well to the theoretical model calculated with a log K 0 s0 =3.9±0.7. For uranophane, the best fitting was obtained for a log K 0 s0 =11.7±0.6. The dissolution rate in the presence of bicarbonate gave for soddyite an average value of 6.8(±4.4) 10 -10 mol m -2 s -1 . For uranophane, under the same experimental conditions, the following dissolution rate equation has been derived: r 0 (mol m -2 s -1 )=10 -9±2. [HCO 3 - ] 0.69±0.09 2

Does the dose-solubility ratio affect the mean dissolution time of drugs?

Science.gov (United States)

Lánský, P; Weiss, M

1999-09-01

To present a new model for describing drug dissolution. On the basis of the new model to characterize the dissolution profile by the distribution function of the random dissolution time of a drug molecule, which generalizes the classical first order model. Instead of assuming a constant fractional dissolution rate, as in the classical model, it is considered that the fractional dissolution rate is a decreasing function of the dissolved amount controlled by the dose-solubility ratio. The differential equation derived from this assumption is solved and the distribution measures (half-dissolution time, mean dissolution time, relative dispersion of the dissolution time, dissolution time density, and fractional dissolution rate) are calculated. Finally, instead of monotonically decreasing the fractional dissolution rate, a generalization resulting in zero dissolution rate at time origin is introduced. The behavior of the model is divided into two regions defined by q, the ratio of the dose to the solubility level: q 1 (saturation of the solution, saturation time). The singular case q = 1 is also treated and in this situation the mean as well as the relative dispersion of the dissolution time increase to infinity. The model was successfully fitted to data (1). This empirical model is descriptive without detailed physical reasoning behind its derivation. According to the model, the mean dissolution time is affected by the dose-solubility ratio. Although this prediction appears to be in accordance with preliminary application, further validation based on more suitable experimental data is required.

Kinetics of Inorganic Calcite Dissolution in Seawater under Pressure

Science.gov (United States)

Dong, S.; Subhas, A.; Rollins, N.; Berelson, W.; Adkins, J. F.

2016-02-01

While understanding calcium carbonate dissolution is vital in constructing global carbon cycles and predicting the effect of seawater acidification as a result of increasing atmospheric CO2, there is still a major debate over the basic formulation of a dissolution rate law. The kinetics of calcium carbonate dissolution are typically described by the equation: Rate=k(1-Ω)n, while Ω=[Ca2+][CO32-]/Ksp. In this study, 13C-labeled calcite is dissolved in unlabeled seawater and the evolving d13C composition of the fluid is traced over time to establish dissolution rate. Instead of changing ion concentration to obtain varying Ω (as in our previous study; Subhas et al. 2015), we changed Ksp by conducting experiments under different pressures (described in theory as ∂lnKsp/∂P=-ΔV/RT, where ΔV is partial molal volume). This involved the construction of a pressure vessel that could hold our sample bag and provide aliquots while remaining pressurized. Pressure experiments were conducted between 0-2000PSI. Results support the conclusion in our previous study that near-equilibrium dissolution rates are highly nonlinear, but give a disparate relationship between undersaturation and dissolution rate if Ω is calculated assuming the specific ΔV embedded in CO2SYS. A revised ΔV from -37cm3 to -65cm3 would make the dissolution formulation equation agree, but clearly appears unreasonable. Our results are explained by a pressure effect on carbonate dissolution kinetics over and above the influence of pressure on Ω. If this is a phenomenon that occurs in nature, then we would predict that dissolution should be occurring shallower in the water column (as sometimes observed) than indicated by standard Ω calculations.

MRI studies of the hydrodynamics in a USP 4 dissolution testing cell.

Science.gov (United States)

Shiko, G; Gladden, L F; Sederman, A J; Connolly, P C; Butler, J M

2011-03-01

We present a detailed study of hydrodynamics inside the flow-through dissolution apparatus when operated according to USP recommendations. The pulsatile flow inside the flow-through cell was measured quantitatively using magnetic resonance imaging (MRI) at a spatial resolution of 234 × 234 μm(2) and slice thickness of 1 mm. We report the experimental protocols developed for in situ MRI studies and the effect that the operating conditions and tablet orientation have on the hydrodynamics inside commercial flow cells. It was found that the flow field inside the dissolution cells was, at most operating conditions, heterogeneous, rather than fully developed laminar flow, and characterised by re-circulation and backward flow. A model tablet was shown to be contacted by a wide distribution of local velocities as a function of position and orientation in the flow cell. The use of 1 mm beads acted as a distributor of the flow but did not suffice to ensure a fully developed laminar flow profile. These results emphasise the necessity to understand the influence of test conditions on dissolution behaviour in defining robust flow-through dissolution methods. Copyright © 2010 Wiley-Liss, Inc.

Studies on Dissolution Enhancement of Prednisolone, a Poorly Water-Soluble Drug by Solid Dispersion Technique

Directory of Open Access Journals (Sweden)

Parvin Zakeri-Milani

2011-06-01

Full Text Available Introduction: Prednisolone is a class II substance according to the Biopharmaceutics Classification System. It is a poorly water soluble agent. The aim of the present study was to improve dissolution rate of a poorly water-soluble drug, prednisolone, by a solid dispersion technique. Methods: Solid dispersion of prednisolone was prepared with PEG 6000 or different carbohydrates such as lactose and dextrin with various ratios of the drug to carrier i.e., 1:10, 1:20 and 1:40. Solid dispersions were prepared by coevaporation method. The evaluation of the properties of the dispersions was performed using dissolution studies, Fourier-transform infrared spectroscopy and x-ray powder diffractometery. Results: The results indicated that lactose is suitable carriers to enhance the in vitro dissolution rate of prednisolone. The data from the x-ray diffraction showed that the drug was still detectable in its solid state in all solid dispersions except solid dispersions prepared by dextrin as carrier. The results from infrared spectroscopy showed no well-defined drug–carrier interactions for coevaporates. Conclusion: Solid dispersion of a poorly water-soluble drug, prednisolone may alleviate the problems of delayed and inconsistent rate of dissolution of the drug.

Development and validation of a dissolution test for lodenafil carbonate based on in vivo data.

Science.gov (United States)

Codevilla, Cristiane Franco; Castilhos, Tamara dos Santos; Cirne, Carolina Araújo; Froehlich, Pedro Eduardo; Bergold, Ana Maria

2014-04-01

Lodenafil carbonate is a phosphodiesterase type 5 inhibitor used for the treatment of erectile dysfunction. Currently, there is no dissolution test reported for lodenafil carbonate and this drug is not listed in any pharmacopoeia. The present study focused on the development and validation of a dissolution test for lodenafil carbonate tablets, using a simulated absorption profile based on in vivo data. The appropriate conditions were determined after testing sink conditions. Different conditions as medium, surfactant concentration and rotation speed were evaluated. The percentage of dose absorbed was calculated by deconvolution, using the Wagner-Nelson method. According to the obtained results, the use of 0.1 M HCl + 1.5% SLS (900 mL, at 37 + 0.5 °C) as the dissolution medium, paddles at 25 rpm were considered adequate. The samples were quantified by UV spectroscopy at 295 nm and the validation was performed according to international guidelines. The method showed specificity, linearity, accuracy and precision, within the acceptable range. Kinetics of drug release was better described by the first-order model. The proposed dissolution test can be used for the routine quality control of lodenafil carbonate in tablets.

Characterization of spent fuel hulls and dissolution residues

International Nuclear Information System (INIS)

Gue, J.P.; Andriessen, H.

1985-04-01

The main results obtained within the framework of CEC programmes, by KFK, UKAEA and CEA, are reviewed concerning the characterization of dissolution wastes. The contents were determined of the main radioactive emitters contained in the hulls originating in a whole fuel assembly sampled at the La Hague plant, or from Dounreay PFR fuels. Radiochemical characterizations were carried out by different methods including neutron emission measurement, alpha and beta-gamma spectrometry, and mass spectrometry. Decontamination of the hulls by using rinsings and supplementary treatment were also dealt with. The ignition and explosion risks associated with the zircaloy fines formed during the shearing of LWR fuels were examined, and the ignition properties of irradiated and unirradiated zircaloy powders were determined and compared. The physical properties and compositions of the dissolution residues of PFR fuels were defined, in order to conduct tests on the immobilization of these wastes in cement

Mechanisms and kinetics laws of inactive R7T7 reference glass dissolution in water at 90 deg C: initial dissolution rate measurements

International Nuclear Information System (INIS)

Advocat, T.; Ghaleb, D.; Vernaz, E.

1993-02-01

The initial dissolution rate of inactive R7T7 reference glass was measured at 90 deg C in dilute aqueous solutions first at unspecified pH, then with imposed pH values. In distilled water, R7T7 glass corrosion initially involved preferential extraction of boron and network modifier elements (Li, Na, Ca) as long as the solution pH remained acid. When the solution pH became alkaline, glass dissolution was stoichiometric. These two mechanisms were confirmed by dissolution tests in aqueous solutions at imposed pH values under acid and alkaline conditions. The initial dissolution rate r 0 in mole.cm -3 .s -1 also increased significantly in alkaline media when the pH of the aqueous phase increased: in slightly acid media, selective glass dissolution formed a residual, de-alkalinized, hydrated glass that was characterized by transmission electron microscopy and secondary ion mass spectrometry. Under steady-state dissolution conditions, the initial glass corrosion rate (in mole.cm -3 .s -1 ) was: in acid and alkaline media, amorphous and crystallized alteration products formed after complete dissolution of the silicated glass network. The first products formed consisted mainly of Zr, Rare Earths, Fe and Al. (author). 67 refs., 29 figs., 26 tabs., 21 plates

Actor bonds after relationship dissolution

DEFF Research Database (Denmark)

Skaates, Maria Anne

2000-01-01

Most of the presented papers at the 1st NoRD Workshop can be classified as belonging to the business marketing approach to relationship dissolution. Two papers were conceptual, and the remaining six were empirical studies. The first conceptual study by Skaates (2000) focuses on the nature...... of the actor bonds that remain after a business relationship has ended. The study suggests that an interdisciplinary approach would provide a richer understanding of the phenomenon; this could be achieved by using e.g. Bourdieu's sociological concepts in dissolution research....

Mechanism of the transpassive dissolution and secondary passivation of chromium in sulphuric acid solutions

International Nuclear Information System (INIS)

Bojinov, M.; Betova, I.; Raicheff, R.; Fabricius, G.; Laitinen, T.; Saario, T.

1998-01-01

The transpassive dissolution and secondary passivation of Cr in 1..10 M H 2 SO 4 solutions were studied by a combination of different electrochemical methods. The steady-state polarization curves for transpassive dissolution exhibited a Tafel behaviour with a slope being independent on the acid concentration. Lower dissolution rates were measured for higher acid concentrations. Ring-disk measurements showed a release of both soluble Cr(VI) and Cr(III) during transpassivity. Impedance spectra were qualititatively similar in all acid concentrations, comprising one capacitive and two inductive semicircles. A kinetic model comprising two parallel transpassive dissolution paths was consistent with the experimental results. Typical passivation diagrams were observed for Cr in 10 M H 2 SO 4 , and a secondary passive state was established at higher potentials. The formation of the secondary passive film was confirmed by contact electric resistance (CER) measurements. A renewed version of the surface charge approach was consistent with the experimental results in the region of the secondary passivation. (orig.)

Laboratory simulation of salt dissolution during waste removal

International Nuclear Information System (INIS)

Wiersma, B.J.; Parish, W.R.

1997-01-01

Laboratory experiments were performed to support the field demonstration of improved techniques for salt dissolution in waste tanks at the Savannah River Site. The tests were designed to investigate three density driven techniques for salt dissolution: (1) Drain-Add-Sit-Remove, (2) Modified Density Gradient, and (3) Continuous Salt Mining. Salt dissolution was observed to be a very rapid process as salt solutions with densities between 1.38-1.4 were frequently removed. Slower addition and removal rates and locating the outlet line at deeper levels below the top of the saltcake provided the best contact between the dissolution water and the saltcake. It was observed that dissolution with 1 M sodium hydroxide solution resulted in salt solutions that were within the current inhibitor requirements for the prevention of stress corrosion cracking. This result was independent of the density driven technique. However, if inhibited water (0.01 M sodium hydroxide and 0.011 M sodium nitrite) was utilized, the salt solutions were frequently outside the inhibitor requirements. Corrosion testing at conditions similar to the environments expected during waste removal was recommended

Investigation of dissolution kinetics of a Nigerian columbite in ...

African Journals Online (AJOL)

Investigation of dissolution kinetics of a Nigerian columbite in hydrofluoric acid using the shrinking core model. ... Experimental results indicate that the dissolution rate is chemical reaction controlled, with reaction order of 0.57. Dissolution of over 90 % of the columbite was achieved in 5 h, using 20 M HF at 90 oC with 100 ...

Effects of pore forming agents of potassium bicarbonate and drug loading method against dissolution mechanisms of amoxicillin drugs encapsulated in hydrogel full-Ipn chitosan-poly(N-vinylcaprolactam) as a floating drug delivery system

Science.gov (United States)

Aini, Nurul; Rahayu, Dyah Utami Cahyaning; Budianto, Emil

2018-04-01

The limitation of amoxicillin trihydrate in the treatment of H. pylori bacteria is relatively short retention time in the stomach. The FDDS (Floating Drug Delivery System) amoxicillin trihydrate into a chitosan-poly(N-vinylcaprolactam) full-Ipn hydrogel matrix using a pore-forming agent KHCO3 is expected to overcome these limitations. The pore-forming agent to be used is 15% KHCO3 compound. Chemical kinetics approach is performed to determine the dissolution mechanism of amoxicillin trihydrate from K-PNVCL hydrogel in vitro on gastric pH and characterization using SEM performed to confirm the dissolution mechanism. Hydrogels with the addition of pore-forming agents will be loading in situ loading and post loading. Fourier Transform Infra Red (FTIR) spectroscopy was used to characterize K-PNVCL and UV-Vis hydrogels used to calculate the efficiency of encapsulation and drug dissolution rate in K-PNVCL hydrogel. Hydrogel K-PNVCL / KHCO3 that encapsulated by in situ loading method resulted in an encapsulation efficiency of 93.5% and dissolution of 93.4%. While the Hydrogel K-PNVCL / KHCO3 which is drug encapsulation resulted in an encapsulation efficiency of 87.2% with dissolution of 81.5%. Chemical kinetics approach to in situ encapsulation of loading and post loading shows the dissolution mechanism occurring in the K-PNVCL / KHCO3 hydrogel matrix occurs by diffusion. Observation using optical microscope and SEM showed the mechanism of drug dissolution in Hydrogel K-PNVCL occurred by diffusion.

Effect of glucosamine HCl on dissolution and solid state behaviours of piroxicam upon milling.

Science.gov (United States)

Al-Hamidi, Hiba; Edwards, Alison A; Douroumis, Dionysis; Asare-Addo, Kofi; Nayebi, Alireza Mohajjel; Reyhani-Rad, Siamak; Mahmoudi, Javad; Nokhodchi, Ali

2013-03-01

Piroxicam is a non-steroidal anti-inflammatory drug that is characterised by low solubility and high permeability. In order to improve the drug dissolution rate, the co-grinding method was used as an approach to prepare piroxicam co-ground in the carriers such as glucosamine hydrochloride. As, this amino sugar (glucosamine HCl) has been shown to decrease pain and improve mobility in osteoarthritis in joints, therefore, the incorporation of glucosamine in piroxicam formulations would be expected to offer additional benefits to patients. The effect of the order of grinding on the dissolution of piroxicam was also investigated. Co-ground drug and glucosamine were prepared in different ratios using a ball mill. The samples were then subjected to different grinding times. In order to investigate the effect of the grinding process on the dissolution behaviour of piroxicam, the drug was ground separately in the absence of glucosamine. Mixtures of ground piroxicam and unground D-glucosamine HCl were prepared. Physical mixtures of piroxicam and glucosamine were also prepared for comparison. The properties of prepared co-ground systems and physical mixtures were studied using a dissolution tester, FTIR, SEM, XRPD and DSC. These results showed that the presence of glucosamine HCl can increase dissolution rate of piroxicam compared to pure piroxicam. Generally, all dissolution profiles showed the fastest dissolution rate when ground piroxicam was mixed with unground glucosamine. This was closely followed by the co-grinding of piroxicam with glucosamine where lower grinding times showed the fastest dissolution. The solid state studies showed that the grinding of piroxicam for longer times had no effect on polymorphic form of piroxicam, whereas mixtures of piroxicam-glucosamine ground for longer times (60 min) converted piroxicam polymorph II to polymorph I. Copyright © 2012 Elsevier B.V. All rights reserved.

Dissolution behavior of PFBR MOX fuel in nitric acid

International Nuclear Information System (INIS)

Kelkar, Anoop; Kapoor, Y.S.; Singh, Mamta; Meena, D.L.; Pandey, Ashish; Bhatt, R.B.; Behere, P.G.

2017-01-01

Present paper describes the dissolution characteristics of PFBR MOX fuel (U,Pu)O 2 in nitric acid. An overview of batch dissolution experiments, studying the percentage dissolution of uranium and plutonium in (U, Pu)O 2 MOX sintered pellets with different percentage of PuO 2 with reference to time and nitric acid concentration are described. 90% of uranium and plutonium of PFBR MOX gets dissolves in 2 hrs and amount of residue increases with the decrease in nitric acid concentration. Overall variation in percentage residue in PFBR MOX fuel after dissolution test also described. (author)

Do Workplace Sex Ratios Affect Partnership Formation and Dissolution?

DEFF Research Database (Denmark)

Svarer, Michael

In this paper, I analyse the association between workplace sex ratios and partnership formation and dissolution. I find that the risk of dissolution increases with the fraction of coworkers of the opposite sex at both the female and male workplace. On the other hand, workplace sex ratios are not ......In this paper, I analyse the association between workplace sex ratios and partnership formation and dissolution. I find that the risk of dissolution increases with the fraction of coworkers of the opposite sex at both the female and male workplace. On the other hand, workplace sex ratios...

The complexity of nanoparticle dissolution and its importance in nanotoxicological studies

International Nuclear Information System (INIS)

Misra, Superb K.; Dybowska, Agnieszka; Berhanu, Deborah; Luoma, Samuel N.; Valsami-Jones, Eugenia

2012-01-01

Dissolution of nanoparticles (NPs) is an important property that alters their abundance and is often a critical step in determining safety of nanoparticles. The dissolution status of the NPs in exposure media (i.e. whether they remain in particulate form or dissolve — and to what extent), strongly affects the uptake pathway, toxicity mechanisms and the environmental compartment in which NPs will have the highest potential impact. A review of available dissolution data on NPs demonstrates there is a range of potential outcomes depending on the NPs and the exposure media. For example two nominally identical nanoparticles, in terms of size and composition, could have totally different dissolution behaviours, subject to different surface modifications. Therefore, it is imperative that toxicological studies are conducted in conjunction with dissolution of NPs to establish the true biological effect of NPs and hence, assist in their regulation. -- Graphical abstract: Various physicochemical factors affecting dissolution of nanoparticles. Highlights: ► In this study we discuss dissolution of nanoparticles. ► Physicochemical properties of nanoparticles influence dissolution. ► Measuring dissolution of nanoparticles can help to understand their biological response.

Optimization of the solvent-based dissolution method to sample volatile organic compound vapors for compound-specific isotope analysis.

Science.gov (United States)

Bouchard, Daniel; Wanner, Philipp; Luo, Hong; McLoughlin, Patrick W; Henderson, James K; Pirkle, Robert J; Hunkeler, Daniel

2017-10-20

The methodology of the solvent-based dissolution method used to sample gas phase volatile organic compounds (VOC) for compound-specific isotope analysis (CSIA) was optimized to lower the method detection limits for TCE and benzene. The sampling methodology previously evaluated by [1] consists in pulling the air through a solvent to dissolve and accumulate the gaseous VOC. After the sampling process, the solvent can then be treated similarly as groundwater samples to perform routine CSIA by diluting an aliquot of the solvent into water to reach the required concentration of the targeted contaminant. Among solvents tested, tetraethylene glycol dimethyl ether (TGDE) showed the best aptitude for the method. TGDE has a great affinity with TCE and benzene, hence efficiently dissolving the compounds during their transition through the solvent. The method detection limit for TCE (5±1μg/m 3 ) and benzene (1.7±0.5μg/m 3 ) is lower when using TGDE compared to methanol, which was previously used (385μg/m 3 for TCE and 130μg/m 3 for benzene) [2]. The method detection limit refers to the minimal gas phase concentration in ambient air required to load sufficient VOC mass into TGDE to perform δ 13 C analysis. Due to a different analytical procedure, the method detection limit associated with δ 37 Cl analysis was found to be 156±6μg/m 3 for TCE. Furthermore, the experimental results validated the relationship between the gas phase TCE and the progressive accumulation of dissolved TCE in the solvent during the sampling process. Accordingly, based on the air-solvent partitioning coefficient, the sampling methodology (e.g. sampling rate, sampling duration, amount of solvent) and the final TCE concentration in the solvent, the concentration of TCE in the gas phase prevailing during the sampling event can be determined. Moreover, the possibility to analyse for TCE concentration in the solvent after sampling (or other targeted VOCs) allows the field deployment of the sampling

Dissolution Flowsheet for High Flux Isotope Reactor Fuel

Energy Technology Data Exchange (ETDEWEB)

Daniel, W. E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Rudisill, T. S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); O' Rourke, P. E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Karay, N. S [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2016-09-27

As part of the Spent Nuclear Fuel (SNF) processing campaign, H-Canyon is planning to begin dissolving High Flux Isotope Reactor (HFIR) fuel in late FY17 or early FY18. Each HFIR fuel core contains inner and outer fuel elements which were fabricated from uranium oxide (U₃O₈) dispersed in a continuous Al phase using traditional powder metallurgy techniques. Fuels fabricated in this manner, like other SNF’s processed in H-Canyon, dissolve by the same general mechanisms with similar gas generation rates and the production of H₂. The HFIR fuel cores will be dissolved and the recovered U will be down-blended into low-enriched U. HFIR fuel was previously processed in H-Canyon using a unique insert in both the 6.1D and 6.4D dissolvers. Multiple cores will be charged to the same dissolver solution maximizing the concentration of dissolved Al. The objective of this study was to identify flowsheet conditions through literature review and laboratory experimentation to safely and efficiently dissolve the HFIR fuel in H-Canyon. Laboratory-scale experiments were performed to evaluate the dissolution of HFIR fuel using both Al 1100 and Al 6061 T6 alloy coupons. The Al 1100 alloy was considered a representative surrogate which provided an upper bound on the generation of flammable (i.e., H₂) gas during the dissolution process. The dissolution of the Al 6061 T6 alloy proceeded at a slower rate than the Al 1100 alloy, and was used to verify that the target Al concentration in solution could be achieved for the selected Hg concentration. Mass spectrometry and Raman spectroscopy were used to provide continuous monitoring of the concentration of H₂ and other permanent gases in the dissolution offgas, allowing the development of H₂ generation rate profiles. The H₂ generation rates were subsequently used to evaluate if a full HFIR core could be dissolved in an H-Canyon dissolver without exceeding 60% of the

Dissolution-Enlarged Fractures Imaging Using Electrical Resistivity Tomography (ERT)

Science.gov (United States)

Siami-Irdemoosa, Elnaz

In recent years the electrical imaging techniques have been largely applied to geotechnical and environmental investigations. These techniques have proven to be the best geophysical methods for site investigations in karst terrain, particularly when the overburden soil is clay-dominated. Karst is terrain with a special landscape and distinctive hydrological system developed by dissolution of rocks, particularly carbonate rocks such as limestone and dolomite, made by enlarging fractures into underground conduits that can enlarge into caverns, and in some cases collapse to form sinkholes. Bedding planes, joints, and faults are the principal structural guides for underground flow and dissolution in almost all karstified rocks. Despite the important role of fractures in karst development, the geometry of dissolution-enlarged fractures remain poorly unknown. These features are characterized by an strong contrast with the surrounding formations in terms of physical properties, such as electrical resistivity. Electrical resistivity tomography (ERT) was used as the primary geophysical tool to image the subsurface in a karst terrain in Greene County, Missouri. Pattern, orientation and density of the joint sets were interpreted from ERT data in the investigation site. The Multi-channel Analysis of Surface Wave (MASW) method and coring were employed to validate the interpretation results. Two sets of orthogonal visually prominent joints have been identified in the investigation site: north-south trending joint sets and west-east trending joint sets. However, most of the visually prominent joint sets are associated with either cultural features that concentrate runoff, natural surface drainage features or natural surface drainage.

Aplicación de los Sistemas de Información Geográfica para la gestión de la malla vial de la ciudad de Medellín

Directory of Open Access Journals (Sweden)

Jaime A. Zapata Duque

2012-12-01

Full Text Available El estado de la malla vial depende fundamentalmente de factores tales como el tráfico, características estructurales y funcionales del pavimento y condiciones climatológicas locales, y su mantenimiento tiene importantes implicaciones espaciales. Este documento describe el proceso de implementación del sistema de gestión de pavimentos de la ciudad de Medellín, desarrollado en una plataforma SIG. El sistema está soportado en una geodatabase corporativa de inventario y diagnóstico, el cual alimenta un software de modelación del deterioro del pavimento y arroja recomendaciones de intervención en cada segmento vial. Este sistema sirve como apoyo a las autoridades encargadas a la toma de decisiones, con el fin de realizar la planeación del mantenimiento de la malla vial, optimizar los recursos disponibles y ofrecer un mejor servicio a la comunidad.

Toward an in vivo dissolution methodology: a comparison of phosphate and bicarbonate buffers.

Science.gov (United States)

Sheng, Jennifer J; McNamara, Daniel P; Amidon, Gordon L

2009-01-01

The purpose of this research was to evaluate the difference between the pharmaceutical phosphate buffers and the gastrointestinal bicarbonates in dissolution of ketoprofen and indomethacin, to illustrate the dependence of buffer differential on biopharmaceutical properties of BCS II weak acids, and to recommend phosphate buffers equivalent to bicarbonates. The intrinsic dissolution rates of ketoprofen and indomethacin were experimentally measured using a rotating disk method at 37 degrees C in USP SIF/FaSSIF and various concentrations of bicarbonates. Theoretical models including an improved reaction plane model and a film model were applied to estimate the surrogate phosphate buffers equivalent to the bicarbonates. Experimental results show that the intrinsic dissolution rates of ketoprofen and indomethacin in USP and FaSSIF phosphate buffers are 1.5-3.0 times that in the 15 mM bicarbonates. Theoretical analysis demonstrates that the buffer differential is largely dependent on the drug pK(a) and second on solubility, and weakly dependent on the drug diffusivity. Further, in accordance with the drug pK(a), solubility and diffusivity, a simple phosphate surrogate was proposed to match an average bicarbonate value (15 mM) of the upper gastrointestinal region. Specifically, phosphate buffers of 13-15 mM and 3-4 mM were recommended for ketoprofen and indomethacin, respectively. For both ketoprofen and indomethacin, the intrinsic dissolution using the phosphate surrogate buffers closely approximated the 15 mM bicarbonate buffer. This work demonstrates the substantial difference between pharmaceutical phosphates and physiological bicarbonates in determining the drug intrinsic dissolution rates of BCS II weak acids, such as ketoprofen and indomethacin. Surrogate phosphates were recommended in order to closely reflect the in vivo dissolution of ketoprofen and indomethacin in gastrointestinal bicarbonates, which has significant implications for defining buffer systems for

Dissolution of cellulose in ionic liquid: A review

Science.gov (United States)

Mohd, N.; Draman, S. F. S.; Salleh, M. S. N.; Yusof, N. B.

2017-02-01

Dissolution of cellulose with ionic liquids (IL) and deep eutectic solvent (DES) lets the comprehensive dissolution of cellulose. Basically, cellulose can be dissolved, in some hydrophilic ionic liquids, such as 1-butyl-3-methylimidazolium chloride (BMIMCl) and 1-allyl-3-methylimidazolium chloride (AMIMCl). Chloride based ionic liquids are suitable solvents for cellulose dissolution. Although the ILs is very useful in fine chemical industry, its application in the pharmaceutical and food industry have been very limited due to issues with toxicity, purity, and high cost. Seeing to these limitations, new green alternative solvent which is DES was used. This green solvents, may be definitely treated as the next-generation reagents for more sustainable industrial development. Thus, this review aims to discuss the dissolution of cellulose either with ionic liquids or DES and its application.

The anodic dissolution of zinc and zinc alloys in alkaline solution. II. Al and Zn partial dissolution from 5% Al–Zn coatings

International Nuclear Information System (INIS)

Vu, T.N.; Mokaddem, M.; Volovitch, P.; Ogle, K.

2012-01-01

Graphical abstract: - Abstract: The polarization behavior of a 5 wt% Al–Zn steel coating (Galfan™) has been investigated in alkaline solution using atomic emission spectroelectrochemistry (AESEC). The instantaneous Zn and Al dissolution rates were measured as a function of time during a linear scan and potential step transients. The formation rate of insoluble oxides was determined from the difference between the convoluted total current and the sum of the elemental dissolution currents. It was found that, over a wide potential range, the zinc and aluminum partial currents behaved in a similar way to pure zinc and pure aluminum independently. However, during the period in which zinc was active, aluminum dissolution was inhibited. This is attributed to the inhibitive effect of the first and/or the second states of zinc oxide that are formed during the active potential domain. The third form of zinc oxide, observed at higher potential and responsible for the passivation of zinc dissolution, does not have a measurable effect on the Al dissolution rate.

Dilution physics modeling: Dissolution/precipitation chemistry

International Nuclear Information System (INIS)

Onishi, Y.; Reid, H.C.; Trent, D.S.

1995-09-01

This report documents progress made to date on integrating dilution/precipitation chemistry and new physical models into the TEMPEST thermal-hydraulics computer code. Implementation of dissolution/precipitation chemistry models is necessary for predicting nonhomogeneous, time-dependent, physical/chemical behavior of tank wastes with and without a variety of possible engineered remediation and mitigation activities. Such behavior includes chemical reactions, gas retention, solids resuspension, solids dissolution and generation, solids settling/rising, and convective motion of physical and chemical species. Thus this model development is important from the standpoint of predicting the consequences of various engineered activities, such as mitigation by dilution, retrieval, or pretreatment, that can affect safe operations. The integration of a dissolution/precipitation chemistry module allows the various phase species concentrations to enter into the physical calculations that affect the TEMPEST hydrodynamic flow calculations. The yield strength model of non-Newtonian sludge correlates yield to a power function of solids concentration. Likewise, shear stress is concentration-dependent, and the dissolution/precipitation chemistry calculations develop the species concentration evolution that produces fluid flow resistance changes. Dilution of waste with pure water, molar concentrations of sodium hydroxide, and other chemical streams can be analyzed for the reactive species changes and hydrodynamic flow characteristics

High temperature dissolution of ferrites, chromites and bonaccordite in chelating media

Energy Technology Data Exchange (ETDEWEB)

Sathyaseelan, V.S.; Subramanian, H.; Anupkumar, B.; Rufus, A.L.; Velmurugan, S.; Narasimhan, S.V., E-mail: snv@igcar.gov.in [BARC Facilities, Water and Steam Chemistry Div., Tamilnadu (India)

2010-07-01

Different methods have been employed world wide for the decontamination of reactor coolant system surfaces. The success of a decontamination process mainly depends on the oxide dissolution efficiency of the decontamination formulation. Among the oxides, Fe{sub 3}O{sub 4} undergoes easy dissolution in organic acid media at normal temperatures. However, dissolution of chromites and mixed ferrites is not that easy in organic chelant media at normal temperatures even in the presence of redox reagents. Hence, a high temperature process was attempted for the dissolution of ferrites and chromites. A re-circulation system consisting of an autoclave, pump, heat exchanger etc. all lined with teflon was used for carrying out high temperature dissolution experiments. This study describes the high temperature dissolution kinetics of Fe{sub 3}O{sub 4}, NiFe{sub 2}O{sub 4}, and Cr{sub 2}O{sub 3}. Nitrilotriacetic acid (NTA), a well known solvent for metal oxides, was applied at temperatures ranging from 80 to 180{sup o}C. About six fold increase in dissolution rate was observed for Fe{sub 3}O{sub 4} in this temperature range. Effect of N{sub 2}H{sub 4} on oxide dissolution was studied. Lower dissolution rates were observed for Fe{sub 3}O{sub 4} and NiFe{sub 2}O{sub 4} in the presence of hydrazine. Oxide dissolution efficiency of other chelating agents like EDTA, PDCA etc. and the effect of reducing agents like oxalic acid and ascorbic acid on high temperature dissolution also has been studied. The effect of incorporation of boron and zinc in the iron and chromium oxides has also been studied. Bonaccordite (Ni{sub 2}FeBO{sub 5}) has been observed in the fuel deposits of pressurized Water Reactors especially in the AOA affected plants. Zinc ferrite/chromite are formed in reactors adopting zinc injection passivation technique to control radiation field. Bonaccordite and zinc ferrite/chromite formed over the reactor coolant system structural materials are also difficult to dissolve

Determination of the dissolution slowness surface by study of etched shapes I. Morphology of the dissolution slowness surface and theoretical etched shapes

Science.gov (United States)

Leblois, T.; Tellier, C. R.

1992-07-01

We propose a theoretical model for the anisotropic etching of crystals, in order to be applied in the micromachining. The originality of the model is due to the introduction of dissolution tensors to express the representative surface of the dissolution slowness. The knowledge of the equation of the slowness surface allows us to determine the trajectories of all the elements which compose the starting surface. It is then possible to construct the final etched shape by numerical simulation. Several examples are given in this paper which show that the final etched shapes are correlated to the extrema of the dissolution slowness. Since the slowness surface must be determined from experiments, emphasis is placed on difficulties encountered when we correlate theory to experiments. Nous avons modélisé le processus de dissolution anisotrope des cristaux en vue d'une application à la simulation des formes obtenues par photolithogravure chimique. La principale originalité de ce modèle tient à l'introduction de tenseurs de dissolution pour exprimer la surface représentative de la lenteur de dissolution. La connaissance de l'équation de la lenteur de dissolution permet de calculer les trajectoires des différents éléments constituant la surface de départ puis de reconstituer par simulation la forme dissoute. Les simulations démontrent que les formes limites des cristaux dissous sont corrélées aux extrema de la lenteur de dissolution. La détermination de la surface de la lenteur se faisant à partir de mesures expérimetales, nous nous sommes efforcés de montrer toutes les difficultés attachées à cette analyse.

Can hydrate dissolution experiments predict the fate of a natural hydrate system?

Energy Technology Data Exchange (ETDEWEB)

Hester, K.C.; Peltzer, E.T.; Dunk, R.M.; Walz, P.M.; Brewer, P.G. [Monterey Bay Aquarium Research Inst., Moss Landing, CA (United States); Dendy Sloan, E. [Colorado School of Mines, Golden, CO (United States). Center for Hydrate Research

2008-07-01

Gas hydrates are naturally occurring compounds found in permafrost regions and in oceans. In the natural environment, sufficient temperature and pressure conditions for hydrate formation exist over a significant portion of the ocean. However, in addition to pressure and temperature, the chemical potential of the gas in the hydrate must be equal to the surrounding waters. If the concentration of the gas in surrounding water is under-saturated with respect to the gas in the hydrate, the hydrate will dissolve to drive the system towards chemical equilibrium. This paper presented a dissolution study of exposed hydrate from outcrops at Barkley Canyon, located off Vancouver Island, British Columbia. A previous field experiment on synthetic methane hydrate samples had demonstrated that mass transfer controlled dissolution in under-saturated seawater. However, seafloor hydrate outcrops have been shown to have significant longevity compared to expected dissolution rates based upon convective boundary layer diffusion calculations. An in-situ dissolution experiment was performed on two distinct natural hydrate fabrics in order to help resolve this apparent disconnect between the dissolution rates of synthetic and natural hydrate. The paper presented a map of Barkley Canyon and discussed the field measurements and methods for the study. Exposed outcrops of gas hydrates were cored using a specially constructed stainless steel coring device and a hydraulic ram was located inside the corer. Hydrate samples were cored directly using the a manipulator arm and then injected into a sampling cell. The hydrate was then added to an open mesh exposure container, which allowed for exposure to ambient benthic currents with minimal disturbance. As well, in order to observe the slow dissolution of the hydrate in seawater at Barkley Canyon, time-lapse photography was employed. Last, the paper presented the results of the hydrate fabric porosities and hydrate dissolution rates. It was

Dissolution kinetics of lead telluride in alkali solutions of hydrogen peroxide

International Nuclear Information System (INIS)

Danilova, M.G.; Sveshnikova, L.L.; Stavitskaya, T.A.; Repinskij, S.M.

1991-01-01

Dissolution kinetics of lead telluride in alkali solutions of hydrogen peroxide was investigated. Dependences of change of PbTe dissolution rate on concentration of hydrogen peroxide and alkali in the solution were obtained. It is shown that dissolution rate of lead telluride is affected by dissolution rate of lead oxide, representing the product of ReTe dissolution. The obtained regularities can be explained by change of solution structure with increase of KOH concentration and by the state of hydrogen peroxide in the solution

Method of simultaneous continuous determination of transfer rates of iron and chromium into solution during Fe-Cr alloys dissolution

International Nuclear Information System (INIS)

Shirinov, T.I.; Florianovich, G.M.; Skuratnik, Ya.B.

1978-01-01

Radiometry method of simultaneous continuous registration of transfer rates of iron and chromium into solution from Fe-Cr alloys with various composition has been developed. Using gamma-spectrometer components of Fe-Cr alloys can be determined with high sensitivity in separate samples according to Fe 59 and Cr 51 radioactive labels, obtained by neutron activation. The above method is applied to estimate Fe and Cr transfer rates into H 2 SO 4 solution at the temperature of 50 deg from Fe - 28% Cr alloy during its active dissolution. It is established, that beginning with some seconds of alloy and solution contact, its components transfer into the solution in the same composition, as in the alloy. The method enables to determine Fe with the accuracy of up to 5% and Cr with that of up to 10%

Investigation of the gas formation in dissolution process of nuclear reactor fuel

International Nuclear Information System (INIS)

Zhang Qinfen; Liao Yuanzhong; Chen Yongqing; Sun Shuyun; Fan Yincheng

1987-12-01

The gas formation in dissolution process of two kinds of nuclear fuels was studied. The results shows that the maximum volume flow released from dissolution system is composed of two parts. One of them is air remained in dissolver and pushed out by acid vapor. The other is produced in dissolution reaction. The procedure of calculating the gas amount produced in dissolution process has been given. It is based on variation of components of dissolution solution. The gas amount produced in dissolution process of spent UO 2 fuel elements was calculated. The condenser system and loading volume of disposal system of tail gas of dissolution of spent fuel were discussed

Chemical dissolution of spent fuel and cladding using complexed fluoride species

International Nuclear Information System (INIS)

Rance, P.J.W.; Freeman, G.A.; Mishin, V.; Issoupov, V.

2001-01-01

The dissolution of LWR fuel cladding using two fluoride ion donors, HBF 4 and K 2 ZrF 6 , in combination with nitric acid has been investigated as a potential reprocessing head-end process suitable for chemical decladding and fuel dissolution in a single process step. Maximum zirconium concentrations in the order of 0,75 to 1 molar have been achieved and dissolution found to continue to low F:Zr ratios albeit at ever decreasing rates. Dissolution rates of un-oxidised zirconium based fuel claddings are fast, whereas oxidised materials exhibit an induction period prior to dissolution. Data is presented relating to the rates of dissolution of cladding and UO 2 fuels under various conditions. (author)

Economic incentives for additional critical experimentation applicable to fuel dissolution

International Nuclear Information System (INIS)

Mincey, J.F.; Primm, R.T. III; Waltz, W.R.

1981-01-01

Fuel dissolution operations involving soluble absorbers for criticality control are among the most difficult to establish economical subcritical limits. The paucity of applicable experimental data can significantly hinder a precise determination of a bias in the method chosen for calculation of the required soluble absorber concentration. Resorting to overly conservative bias estimates can result in excessive concentrations of soluble absorbers. Such conservatism can be costly, especially if soluble absorbers are used in a throw-away fashion. An economic scoping study is presented which demonstrates that additional critical experimentation will likely lead to reductions in the soluble absorber (i.e., gadolinium) purchase costs for dissolution operations. The results indicate that anticipated savings maybe more than enough to pay for the experimental costs

High temperature dissolution of chromium substituted nickel ferrite in nitrilotriacetic acid medium

Energy Technology Data Exchange (ETDEWEB)

Sathyaseelan, V.S.; Chandramohan, P.; Velmurugan, S., E-mail: svelu@igcar.gov.in

2016-12-01

High temperature (HT) dissolution of chromium substituted nickel ferrite was carried out with relevance to the decontamination of nuclear reactors by way of chemical dissolution of contaminated corrosion product oxides present on stainless steel coolant circuit surfaces. Chromium substituted nickel ferrites of composition, NiFe{sub (2−x)}Cr{sub x}O{sub 4} (x ≤ 1), was synthetically prepared and characterized. HT dissolution of these oxides was carried out in nitrilotriacetic acid medium at 160 °C. Dissolution was remarkably increased at 160 °C when compared to at 85 °C in a reducing decontamination formulation. Complete dissolution could be achieved for the oxides with chromium content 0 and 0.2. Increasing the chromium content brought about a marked reduction in the dissolution rate. About 40 fold decrease in rate of dissolution was observed when chromium was increased from 0 to 1. The rate of dissolution was not very significantly reduced in the presence of N{sub 2}H{sub 4}. Dissolution of oxide was found to be stoichiometric. - Highlights: • Dissolution of NiFe{sub (2−x)}Cr{sub x}O{sub 4} was remarkably increased at 160 °C in NTA medium. • The dissolution was significantly decreasing with the increase in Cr content in the oxide. • Dissolution rate is dependent on the lability of metal-oxo bonds. • The rate of dissolution was not significantly reduced in the presence of N{sub 2}H{sub 4.} • NTA at high temperature is effective for decontamination of stainless steel surfaces.

Toward a consistent model for glass dissolution

International Nuclear Information System (INIS)

Strachan, D.M.; McGrail, B.P.; Bourcier, W.L.

1994-01-01

Understanding the process of glass dissolution in aqueous media has advanced significantly over the last 10 years through the efforts of many scientists around the world. Mathematical models describing the glass dissolution process have also advanced from simple empirical functions to structured models based on fundamental principles of physics, chemistry, and thermodynamics. Although borosilicate glass has been selected as the waste form for disposal of high-level wastes in at least 5 countries, there is no international consensus on the fundamental methodology for modeling glass dissolution that could be used in assessing the long term performance of waste glasses in a geologic repository setting. Each repository program is developing their own model and supporting experimental data. In this paper, we critically evaluate a selected set of these structured models and show that a consistent methodology for modeling glass dissolution processes is available. We also propose a strategy for a future coordinated effort to obtain the model input parameters that are needed for long-term performance assessments of glass in a geologic repository. (author) 4 figs., tabs., 75 refs

Dissolution performance of plutonium nitride based fuel materials

Energy Technology Data Exchange (ETDEWEB)

Aneheim, E.; Hedberg, M. [Nuclear Chemistry, Chemistry and Chemical Engineering, Chalmers University of Technology, Kemivaegen 4, Gothenburg, SE41296 (Sweden)

2016-07-01

Nitride fuels have been regarded as one viable fuel option for Generation IV reactors due to their positive features compared to oxides. To be able to close the fuel cycle and follow the Generation IV concept, nitrides must, however, demonstrate their ability to be reprocessed. This means that the dissolution performance of actinide based nitrides has to be thoroughly investigated and assessed. As the zirconium stabilized nitrides show even better potential as fuel material than does the pure actinide containing nitrides, investigations on the dissolution behavior of both PuN and (Pu,Zr)N has been undertaken. If possible it is desirable to perform the fuel dissolutions using nitric acid. This, as most reprocessing strategies using solvent-solvent extraction are based on a nitride containing aqueous matrix. (Pu,Zr)N/C microspheres were produced using internal gelation. The spheres dissolution performance was investigated using nitric acid with and without additions of HF and Ag(II). In addition PuN fuel pellets were produced from powder and their dissolution performance were also assessed in a nitric acid based setting. It appears that both PuN and (Pu,Zr)N/C fuel material can be completely dissolved in nitric acid of high concentration with the use of catalytic amounts of HF. The amount of HF added strongly affects dissolution kinetics of (Pu, Zr)N and the presence of HF affects the 2 solutes differently, possibly due to inhomogeneity o the initial material. Large additions of Ag(II) can also be used to facilitate the dissolution of (Pu,Zr)N in nitric acid. PuN can be dissolved by pure nitric acid of high concentration at room temperature while (Pu, Zr)N is unaffected under similar conditions. At elevated temperature (reflux), (Pu,Zr)N can, however, also be dissolved by concentrated pure nitric acid.

Industry's View on Using Quality Control, Biorelevant, and Clinically Relevant Dissolution Tests for Pharmaceutical Development, Registration, and Commercialization.

Science.gov (United States)

Grady, Haiyan; Elder, David; Webster, Gregory K; Mao, Yun; Lin, Yiqing; Flanagan, Talia; Mann, James; Blanchard, Andy; Cohen, Michael J; Lin, Judy; Kesisoglou, Filippos; Hermans, Andre; Abend, Andreas; Zhang, Limin; Curran, David

2018-01-01

This article intends to summarize the current views of the IQ Consortium Dissolution Working Group, which comprises various industry companies, on the roles of dissolution testing throughout pharmaceutical product development, registration, commercialization, and beyond. Over the past 3 decades, dissolution testing has evolved from a routine and straightforward test as a component of end-product release into a comprehensive set of tools that the developer can deploy at various stages of the product life cycle. The definitions of commonly used dissolution approaches, how they relate to one another and how they may be applied in modern drug development, and life cycle management is described in this article. Specifically, this article discusses the purpose, advantages, and limitations of quality control, biorelevant, and clinically relevant dissolution methods. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

The dissolution kinetics of magnetite under regenerative conditions

International Nuclear Information System (INIS)

Ranganathan, S.

2004-01-01

Dissolution studies of magnetite were carried out under regenerative conditions in dilute chemical decontamination formulations. During regeneration of the formulation, the H + from the strong acid cation exchange resin gets released and the metal is absorbed on the resin. The efficiency of the regenerative process depends on the stability constants of the complexes involved and the selectivity on the ion exchange column. The regenerative condition helps to maintain a constant chelating agent concentration and pH during the dissolution experiment. Such a condition is ideal for obtaining data on the dissolution behaviour of the corrosion products with special application to actual reactor decontamination. The ethylenediaminetetraacetic acid (EDTA) based formulation used was found to be ineffective due to the high stability constant of Fe(III)-EDTA complex, which is not easily cleaved by the cation exchange resin. Hence, knowledge of the kinetics of magnetite dissolution under regenerative condition is of primary importance. The 2,6-pyridinedicarboxylic acid formulation is found to be better for the dissolution of Fe 3 O 4 in both static and regenerative modes in the presence of reductants than nitrilotriacetic acid and EDTA. (orig.)

The dissolution kinetics of magnetite under regenerative conditions

Energy Technology Data Exchange (ETDEWEB)

Ranganathan, S. [New Brunswick Univ., Frederiction (Canada). Dept. of Chemical Engineering; Raghavan, P.S.; Gopalan, R.; Srinivasan, M.P.; Narasimhan, S.V. [Water and Steam Chemistry Lab. of Bhabha Atomic Research Centre (BARC) (India)

2004-07-01

Dissolution studies of magnetite were carried out under regenerative conditions in dilute chemical decontamination formulations. During regeneration of the formulation, the H{sup +} from the strong acid cation exchange resin gets released and the metal is absorbed on the resin. The efficiency of the regenerative process depends on the stability constants of the complexes involved and the selectivity on the ion exchange column. The regenerative condition helps to maintain a constant chelating agent concentration and pH during the dissolution experiment. Such a condition is ideal for obtaining data on the dissolution behaviour of the corrosion products with special application to actual reactor decontamination. The ethylenediaminetetraacetic acid (EDTA) based formulation used was found to be ineffective due to the high stability constant of Fe(III)-EDTA complex, which is not easily cleaved by the cation exchange resin. Hence, knowledge of the kinetics of magnetite dissolution under regenerative condition is of primary importance. The 2,6-pyridinedicarboxylic acid formulation is found to be better for the dissolution of Fe{sub 3}O{sub 4} in both static and regenerative modes in the presence of reductants than nitrilotriacetic acid and EDTA. (orig.)

Accelerated dissolution testing for controlled release microspheres using the flow-through dissolution apparatus.

Science.gov (United States)

Collier, Jarrod W; Thakare, Mohan; Garner, Solomon T; Israel, Bridg'ette; Ahmed, Hisham; Granade, Saundra; Strong, Deborah L; Price, James C; Capomacchia, A C

2009-01-01

Theophylline controlled release capsules (THEO-24 CR) were used as a model system to evaluate accelerated dissolution tests for process and quality control and formulation development of controlled release formulations. Dissolution test acceleration was provided by increasing temperature, pH, flow rate, or adding surfactant. Electron microscope studies on the theophylline microspheres subsequent to each experiment showed that at pH values of 6.6 and 7.6 the microspheres remained intact, but at pH 8.6 they showed deterioration. As temperature was increased from 37-57 degrees C, no change in microsphere integrity was noted. Increased flow rate also showed no detrimental effect on integrity. The effect of increased temperature was determined to be the statistically significant variable.

Disintegration of highly soluble immediate release tablets: a surrogate for dissolution.

Science.gov (United States)

Gupta, Abhay; Hunt, Robert L; Shah, Rakhi B; Sayeed, Vilayat A; Khan, Mansoor A

2009-01-01

The purpose of the work was to investigate correlation between disintegration and dissolution for immediate release tablets containing a high solubility drug and to identify formulations where disintegration test, instead of the dissolution test, may be used as the acceptance criteria based on International Conference on Harmonization Q6A guidelines. A statistical design of experiments was used to study the effect of filler, binder, disintegrating agent, and tablet hardness on the disintegration and dissolution of verapamil hydrochloride tablets. All formulation variables, i.e., filler, binder, and disintegrating agent, were found to influence tablet dissolution and disintegration, with the filler and disintegrating agent exerting the most significant influence. Slower dissolution was observed with increasing disintegration time when either the filler or the disintegrating agent was kept constant. However, no direct corelationship was observed between the disintegration and dissolution across all formulations due to the interactions between different formulation components. Although all tablets containing sodium carboxymethyl cellulose as the disintegrating agent, disintegrated in less than 3 min, half of them failed to meet the US Pharmacopeia 30 dissolution criteria for the verapamil hydrochloride tablets highlighting the dependence of dissolution process on the formulation components other than the disintegrating agent. The results identified only one formulation as suitable for using the disintegration test, instead of the dissolution test, as drug product acceptance criteria and highlight the need for systematic studies before using the disintegration test, instead of the dissolution test as the drug acceptance criteria.

In Vivo Predictive Dissolution: Comparing the Effect of Bicarbonate and Phosphate Buffer on the Dissolution of Weak Acids and Weak Bases.

Science.gov (United States)

Krieg, Brian J; Taghavi, Seyed Mohammad; Amidon, Gordon L; Amidon, Gregory E

2015-09-01

Bicarbonate is the main buffer in the small intestine and it is well known that buffer properties such as pKa can affect the dissolution rate of ionizable drugs. However, bicarbonate buffer is complicated to work with experimentally. Finding a suitable substitute for bicarbonate buffer may provide a way to perform more physiologically relevant dissolution tests. The dissolution of weak acid and weak base drugs was conducted in bicarbonate and phosphate buffer using rotating disk dissolution methodology. Experimental results were compared with the predicted results using the film model approach of (Mooney K, Mintun M, Himmelstein K, Stella V. 1981. J Pharm Sci 70(1):22-32) based on equilibrium assumptions as well as a model accounting for the slow hydration reaction, CO2 + H2 O → H2 CO3 . Assuming carbonic acid is irreversible in the dehydration direction: CO2 + H2 O ← H2 CO3 , the transport analysis can accurately predict rotating disk dissolution of weak acid and weak base drugs in bicarbonate buffer. The predictions show that matching the dissolution of weak acid and weak base drugs in phosphate and bicarbonate buffer is possible. The phosphate buffer concentration necessary to match physiologically relevant bicarbonate buffer [e.g., 10.5 mM (HCO3 (-) ), pH = 6.5] is typically in the range of 1-25 mM and is very dependent upon drug solubility and pKa . © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Determination of uranium metal concentration in irradiated fuel storage basin sludge using selective dissolution

International Nuclear Information System (INIS)

Delegard, C.H.; Sinkov, S.I.; Chenault, J.W.; Schmidt, A.J.; Pool, K.N.; Welsh, T.L.

2014-01-01

Irradiated uranium metal fuel was stored underwater in the K East and K West storage basins at the US Department of Energy Hanford Site. The uranium metal under damaged cladding reacted with water to generate hydrogen gas, uranium oxides, and spalled uranium metal particles which intermingled with other particulates to form sludge. While the fuel has been removed, uranium metal in the sludge remains hazardous. An expeditious routine method to analyze 0.03 wt% uranium metal in the presence of >30 wt% total uranium was needed to support safe sludge management and processing. A selective dissolution method was designed based on the rapid uranium oxide dissolution but very low uranium metal corrosion rates in hot concentrated phosphoric acid. The uranium metal-bearing heel from the phosphoric acid step then is rinsed before the uranium metal is dissolved in hot concentrated nitric acid for analysis. Technical underpinnings of the selective dissolution method, including the influence of sludge components, were investigated to design the steps and define the reagents, quantities, concentrations, temperatures, and times within the selective dissolution analysis. Tests with simulant sludge proved the technique feasible. Tests with genuine sludge showed a 0.0028 ± 0.0037 wt% (at one standard deviation) uranium metal analytical background, a 0.011 wt% detection limit, and a 0.030 wt% quantitation limit in settled (wet) sludge. In tests using genuine K Basin sludge spiked with uranium metal at concentrations above the 0.030 wt% ± 25 % (relative) quantitation limit, uranium metal recoveries averaged 99.5 % with a relative standard deviation of 3.5 %. (author)

Kinetics of dissolution of calcium phosphate (Ca-P bioceramics

Directory of Open Access Journals (Sweden)

Lukas Brazda

2008-06-01

Full Text Available Hydroxyapatite (HAp and β-tricalcium phosphate (β-TCP are widely used bioceramics for surgical or dental applications. This paper is dealing with dissolution kinetics of synthetically prepared β-TCP and four types of HAp granules. Two groups of HAp, treated at different temperatures, each of them with two different granule sizes, were tested. Three corrosive solutions with different pH and simulated body fluid (SBF were used for immersing of the samples. Changes in concentrations of calcium and phosphate ions, pH level and weight changes of the samples were observed. It was found that presence of TRIS buffer enhanced dissolution rate of the β-TCP approximately two times. When exposed to SBF solution, calcium phosphate (most probably hydroxyapatite precipitation predominates over β-TCP dissolution. Results from HAp samples dissolution showed some unexpected findings. Neither heat treatment nor HAp particle size made any major differences in dissolution rate of the same mass of each HAp sample.

Examining the Conservatisms in Dissolution Rates of Commercial Spent Nuclear Fuel

International Nuclear Information System (INIS)

Hanson, Brady D.

2008-01-01

Most models for commercial spent nuclear fuel dissolution are based on data obtained from single-pass flow-through tests. These tests are designed to have a high water volume to fuel surface area ratio so that the concentration of radionuclides in solution are below solubility limits and thus back reactions and the formation of alteration products are minimized. While this method is ideal for determining the dependence of the dissolution rate on various parameters, it is important to examine the differences between these tests and the realistic scenarios that will exist in a geologic repository. Many of the inherent conservatisms that are part of the models are examined. These conservatisms include: limited water, short-term vs. long-term rates, groundwater effects, non-congruent release, radiolysis, and fuel chemistry effects. Each of these conservatisms has the potential to decrease the currently modeled dissolution rates by between a factor of 2 and 200. The combined effects are unknown, but, if quantified, could significantly improve the waste form performance relative to current models.

Modulation of solubility and dissolution of furosemide by preparation of phospholipid complex

Directory of Open Access Journals (Sweden)

Mona Semalty

2014-01-01

Full Text Available Aim: The aim of this study is to improve the solubility and dissolution of furosemide (a potent high ceiling diuretic used for the treatment of hypertension and a Class IV drug that is low solubility and low permeability drug as per the Biopharmaceutical Classification System by preparing its phospholipid complexes or pharmacosomes. Materials and Methods: Furosemide was complexed with phosphatidylcholine in four different molar ratios (1:1, 1:2, 1:3 and 1:4 by conventional solvent-evaporation technique. The pharmacosomes prepared were evaluated for drug content, solubility, X-ray powder diffraction (XRPD and in-vitro dissolution study. Results: Pharmacosomes of furosemide showed high drug content ranging from 88.30% to 100%. XRPD studies confirmed the formation of phospholipid complex and the amorphization of drug in the complex. The water solubility was found to be increased up to six-fold in the complexes. The octanol solubility also increased in the complexes indicating the probable increase in permeability. The in-vitro dissolution profile of the prepared complexes was found to be much better than furosemide. Conclusion: It was concluded that the phospholipid complexes can be effectively used for improving the solubility, dissolution, permeability and hence the bioavailability of furosemide like Class IV drugs.

Microbially mediated barite dissolution in anoxic brines

International Nuclear Information System (INIS)

Ouyang, Bingjie; Akob, Denise M.; Dunlap, Darren; Renock, Devon

2017-01-01

Fluids injected into shale formations during hydraulic fracturing of black shale return with extraordinarily high total-dissolved-solids (TDS) and high concentrations of barium (Ba) and radium (Ra). Barite, BaSO_4, has been implicated as a possible source of Ba as well as a problematic mineral scale that forms on internal well surfaces, often in close association with radiobarite, (Ba,Ra)SO_4. The dissolution of barite by abiotic processes is well quantified. However, the identification of microbial communities in flowback and produced water necessitates the need to understand barite dissolution in the presence of bacteria. Therefore, we evaluated the rates and mechanisms of abiotic and microbially-mediated barite dissolution under anoxic and hypersaline conditions in the laboratory. Barite dissolution experiments were conducted with bacterial enrichment cultures established from produced water from Marcellus Shale wells located in northcentral Pennsylvania. These cultures were dominated by anaerobic halophilic bacteria from the genus Halanaerobium. Dissolved Ba was determined by ICP-OES and barite surfaces were investigated by SEM and AFM. Our results reveal that: 1) higher amounts of barium (up to ∼5 × ) are released from barite in the presence of Halanaerobium cultures compared to brine controls after 30 days of reaction, 2) etch pits that develop on the barite (001) surface in the presence of Halanaerobium exhibit a morphology that is distinct from those that form during control experiments without bacteria, 3) etch pits that develop in the presence of Halanaerobium exhibit a morphology that is similar to the morphology of etch pits formed in the presence of strong organic chelators, EDTA and DTPA, and 4) experiments using dialysis membranes to separate barite from bacteria suggest that direct contact between the two is not required in order to promote dissolution. These results suggest that Halanaerobium increase the rate of barite dissolution in anoxic

Investigating dissolution of mechanically activated olivine for carbonation purposes

International Nuclear Information System (INIS)

Haug, Tove Anette; Kleiv, Rolf Arne; Munz, Ingrid Anne

2010-01-01

Research highlights: → Dissolution of mechanically activated olivine increased with 3 orders of magnitude. → Crystallinity changes of olivine is important for the observed dissolution rates. → Activation probably decreases with the degree of dissolution of each particle. - Abstract: Mineral carbonation is one of several alternatives for CO 2 sequestration and storage. The reaction rates of appropriate minerals with CO 2 , for instance olivine and serpentine with vast resources, are relatively slow in a CO 2 sequestration context and the rates have to be increased to make mineral carbonation a good storage alternative. Increasing the dissolution rate of olivine has been the focus of this paper. Olivine was milled with very high energy intensity using a laboratory planetary mill to investigate the effect of mechanical activation on the Mg extraction potential of olivine in 0.01 M HCl solution at room temperature and pressure. Approximately 30-40% of each sample was dissolved and water samples were taken at the end of each experiment. The pH change was used to calculate time series of the Mg concentrations, which also were compared to the final Mg concentrations in the water samples. Percentage dissolved and the specific reaction rates were estimated from the Mg concentration time series. The measured particle size distributions could not explain the rate constants found, but the specific surface area gave a good trend versus dissolution for samples milled wet and the samples milled with a small addition of water. The samples milled dry had the lowest measured specific surface areas ( 2 /g), but had the highest rate constants. The crystallinity calculated from X-ray diffractograms, was the material parameter with the best fit for the observed differences in the rate constants. Geochemical modelling of mechanically activated materials indicated that factors describing the changes in the material properties related to the activation must be included. The

Efavirenz Dissolution Enhancement I: Co-Micronization

Directory of Open Access Journals (Sweden)

Helvécio Vinícius Antunes Rocha

2012-12-01

Full Text Available AIDS constitutes one of the most serious infectious diseases, representing a major public health priority. Efavirenz (EFV, one of the most widely used drugs for this pathology, belongs to the Class II of the Biopharmaceutics Classification System for drugs with very poor water solubility. To improve EFV’s dissolution profile, changes can be made to the physical properties of the drug that do not lead to any accompanying molecular modifications. Therefore, the study objective was to develop and characterize systems with efavirenz able to improve its dissolution, which were co-processed with sodium lauryl sulfate (SLS and polyvinylpyrrolidone (PVP. The technique used was co-micronization. Three different drug:excipient ratios were tested for each of the two carriers. The drug dispersion dissolution results showed significant improvement for all the co-processed samples in comparison to non-processed material and corresponding physical mixtures. The dissolution profiles obtained for dispersion with co-micronized SLS samples proved superior to those of co-micronized PVP, with the proportion (1:0.25 proving the optimal mixture. The improvements may be explained by the hypothesis that formation of a hydrophilic layer on the surface of the micronized drug increases the wettability of the system formed, corroborated by characterization results indicating no loss of crystallinity and an absence of interaction at the molecular level.

Successful topical dissolution of cholesterol gallbladder stones using ethyl propionate.

Science.gov (United States)

Hofmann, A F; Amelsberg, A; Esch, O; Schteingart, C D; Lyche, K; Jinich, H; Vansonnenberg, E; D'Agostino, H B

1997-06-01

Topical dissolution of cholesterol gallbladder stones using methyl tert-butyl ether (MTBE) is useful in symptomatic patients judged too ill for surgery. Previous studies showed that ethyl propionate (EP), a C5 ester, dissolves cholesterol gallstones rapidly in vitro, but differs from MTBE in being eliminated so rapidly by the liver that blood levels remain undetectable. Our aim was to test EP as a topical dissolution agent for cholesterol gallbladder stones. Five high-risk patients underwent topical dissolution of gallbladder stones by EP. In three patients, the solvent was instilled via a cholecystostomy tube placed previously to treat acute cholecystitis; in two patients, a percutaneous transhepatic catheter was placed in the gallbladder electively. Gallstone dissolution was assessed by chromatography, by gravimetry, and by catheter cholecystography. Total dissolution of gallstones was obtained in four patients after 6-10 hr of lavage; in the fifth patient, partial gallstone dissolution facilitated basketing of the stones. In two patients, cholesterol dissolution was measured and averaged 30 mg/min. Side effects were limited to one episode of transient hypotension and pain at the infusion site; no patient developed somnolence or nausea. Gallstone elimination was associated with relief of symptoms. EP is an acceptable alternative to MTBE for topical dissolution of cholesterol gallbladder stones in high-risk patients. The lower volatility and rapid hepatic extraction of EP suggest that it may be preferable to MTBE in this investigational procedure.

Dissolution rates of over-the-counter painkillers: a comparison among formulations.

Science.gov (United States)

Alemanni, Matteo; Gatoulis, Sergio C; Voelker, Michael

2016-06-01

We wanted to compare the dissolution profile of several over-the-counter analgesics to understand whether the different formulation techniques employed to enhance absorption were associated with variations in the dissolution rate, a parameter known to affect drug absorption. We considered 5 formulations currently marketed in Italy: aspirin tablets (Aspirina Dolore e Infiammazione®), ibuprofen tablets and liquid capsules (Moment®), ibuprofen lysine tablets (Nurofenimmedia®) and dexketoprofen trometamol tablets (Enantyum®). Dissolution tests were performed according to the current USP/NF monograph dissolution procedure. Drug dissolution was evaluated at 1, 3, 6, 15, and 30 minutes since the start of the test. Dissolution was evaluated at three different pH: 1.2, 4.5 and 6.8. Every test was repeated 12 times. The aspirin formulation was by far the most rapid dissolving formulation, among those tested, with more than 80% of the tablet dissolved at 6 minutes for every pH considered. At pH 1.2 and 4.5, only the dexketoprofen formulation was able to reach the dissolution level of aspirin at 30 minutes, but had lower levels of dissolution at the previous time points. Instead, at pH 6.8, most of the formulations approached aspirin dissolution level, but only after 15 minutes. Ibuprofen capsules had the slowest kinetics, with a lag phase the first 6 minutes. Different formulation strategies can lead to great differences in the dissolution rates even among drugs of the same class, suggesting that enhancements in the formulation of painkillers can lead to improvements in drug absorption, and thus in the onset of analgesia.

Influence of oxalic acid on the dissolution kinetics of manganese oxide

Science.gov (United States)

Godunov, E. B.; Artamonova, I. V.; Gorichev, I. G.; Lainer, Yu. A.

2012-11-01

The kinetics and electrochemical processes of the dissolution of manganese oxides with various oxidation states in sulfuric acid solutions containing oxalate ion additives is studied under variable conditions (concentration, pH, temperature). The parameters favoring a higher degree of the dissolution of manganese oxides in acidic media are determined. The optimal conditions are found for the dissolution of manganese oxides in acidic media in the presence of oxalate ions. The mechanism proposed for the dissolution of manganese oxides in sulfuric acid solutions containing oxalic acid is based on the results of kinetic and electrochemical studies. The steps of the dissolution mechanism are discussed.

Dissolution kinetics of purified and synthetic smectites at 25°C and PH∼9

International Nuclear Information System (INIS)

Marty, Nicolas C.M.; Tournassat, Christophe; Gaucher, Eric C.; Chino, Daisuke; Sato, Tsutomu; Villieras, Frederic; Giffaut, Eric; Cama, Jordi; Soler, J.M.

2010-01-01

to edge surface area (ESA), obtained by AFM observations and low-pressure gas adsorption method. ESA normalized dissolution rates of synthetic and natural clay dissolution rates are similar at pH∼9. Si-based dissolution rate law at pH∼9 and 25 deg. C that take into account the effect of the degree of saturation can be proposed either using a rate-law expression as that used by Cama et al. (2000). However, the dissolution rates based on release of Si, Al and Mg were different, indicating non-congruent dissolution reaction and/or formation of new phases. Post mortem AFM and TEM observations of reacted synthetic smectite show (1) significant decrease in particle size and (2) sporadically occurrence of pits on basal surfaces. Hence, it is not possible to definitively assess that dissolution mainly occurs at the edge surface, similarly to dissolution in high pH conditions. Moreover, the EDX analyses indicate decrease in the amount of Mg and Al in the reacted samples. Precipitation of silicate-bearing phases is also observed, although the nature of the precipitates is to be confirmed. Such formations may affect the Si-based dissolution law

Dissolution of the Mors salt dome

International Nuclear Information System (INIS)

Lindstroem Jensen, K.E.

1982-01-01

Regardless of the interpretation of the measured salinity profiles above the Mors salt dome, they can at most be the result of dissolution rates of about 0.004 mm per year. This means that it would take more than 2.5 mill. years to dissolve 10 m of salt. Variations in groun water velocity and cap rock porosity will not significantly change this condition. The stability of the Mors salt dome is therefore not affected by dissolution of the dome. (EG)

In vitro acellular dissolution of mineral fibres: A comparative study.

Science.gov (United States)

Gualtieri, Alessandro F; Pollastri, Simone; Bursi Gandolfi, Nicola; Gualtieri, Magdalena Lassinantti

2018-05-04

The study of the mechanisms by which mineral fibres promote adverse effects in both animals and humans is a hot topic of multidisciplinary research with many aspects that still need to be elucidated. Besides length and diameter, a key parameter that determines the toxicity/pathogenicity of a fibre is biopersistence, one component of which is biodurability. In this paper, biodurability of mineral fibres of social and economic importance (chrysotile, amphibole asbestos and fibrous erionite) has been determined for the first time in a systematic comparative way from in vitro acellular dissolution experiments. Dissolution was possible using the Gamble solution as simulated lung fluid (pH = 4 and at body temperature) so to reproduce the macrophage phagolysosome environment. The investigated mineral fibres display very different dissolution rates. For a 0.25 μm thick fibre, the calculated dissolution time of chrysotile is in the range 94-177 days, very short if compared to that of amphibole fibres (49-245 years), and fibrous erionite (181 years). Diffraction and SEM data on the dissolution products evidence that chrysotile rapidly undergoes amorphization with the formation of a nanophasic silica-rich fibrous metastable pseudomorph as first dissolution step whereas amphibole asbestos and fibrous erionite show minor signs of dissolution even after 9-12 months.

The effect of fuel chemistry on UO{sub 2} dissolution

Energy Technology Data Exchange (ETDEWEB)

Casella, Amanda, E-mail: amanda.casella@pnnl.gov [Pacific Northwest National Laboratory, PO Box 999, MSIN P7-25, Richland, WA 99352 (United States); Hanson, Brady, E-mail: brady.hanson@pnnl.gov [Pacific Northwest National Laboratory, PO Box 999, MSIN P7-27, Richland, WA 99352 (United States); Miller, William [University of Missouri Research Reactor, 1513 Research Park Drive, Columbia, MO 65211 (United States)

2016-08-01

The dissolution rate of both unirradiated UO{sub 2} and used nuclear fuel has been studied by numerous countries as part of the performance assessment of proposed geologic repositories. In the scenario of waste package failure and groundwater contact with the fuel, the effects of variables such as temperature, dissolved oxygen, and water and fuel chemistry on the dissolution rates of the fuel are necessary to provide a quantitative estimate of the potential release over geologic time frames. The primary objective of this research was to determine the influence these parameters, with primary focus on the fuel chemistry, have on the dissolution rate of unirradiated UO{sub 2} under oxidizing repository conditions and compare them to the rates predicted by current dissolution models. Both unirradiated UO{sub 2} and UO{sub 2} doped with varying concentrations of Gd{sub 2}O{sub 3}, to simulate used fuel composition after long time periods when radiolysis has minor contributions to dissolution, were examined. In general, a rise in temperature increased the dissolution rate of UO{sub 2} and had a larger effect on pure UO{sub 2} than on those doped with Gd{sub 2}O{sub 3}. Oxygen dependence was observed in the UO{sub 2} samples with no dopant and increased as the temperature rose; in the doped fuels less dependence was observed. The addition of gadolinia into the UO{sub 2} matrix resulted in a significant decrease in the dissolution rate. The matrix stabilization effect resulting from the dopant proved even more beneficial in lowering the dissolution rate at higher temperatures and dissolved O{sub 2} concentrations in the leachate where the rates would typically be elevated. - Highlights: • UO{sub 2} dissolution rates were measured for a matrix of repository relevant conditions. • Dopants in the UO{sub 2} matrix lowered the dissolution rate. • Reduction in rates by dopants were increased at elevated temperature and O{sub 2} levels. • UO{sub 2} may be overly

Template occluded SBA-15: An effective dissolution enhancer for poorly water-soluble drug

International Nuclear Information System (INIS)

Fu Tingming; Guo Liwei; Le Kang; Wang Tianyao; Lu Jin

2010-01-01

The aim of the present work was to improve the dissolution rate of piroxicam by inclusion into template occluded SBA-15. Our strategy involves directly introducing piroxicam into as-prepared SBA-15 occluded with P123 (EO 20 PO 70 EO 20 ) by self assembling method in acetonitrile/methylene chloride mixture solution. Ultraviolet spectrometry experiment and thermogravimetric analysis-differential scanning calorimetry (TG-DSC) profiles show that the piroxicam and P123 contents in the inclusion compound are 12 wt% and 28 wt%, respectively. X-ray powder diffraction and DSC analysis reveal that the included piroxicam is arranged in amorphous form. N 2 adsorption-desorption experiment indicates that the piroxicam has been introduced to the mesopores instead of precipitating at the outside of the silica material. The inclusion compound was submitted to in vitro dissolution tests, the results show that the piroxicam dissolve from template occluded inclusion compound more rapidly, than these from the piroxicam crystalline and template removed samples in all tested conditions. Thus a facile method to improve the dissolution rate of poorly water-soluble drug was established, and this discovery opens a new avenue for the utilization of templates used for the synthesis of mesoporous materials.

[Aluminum dissolution and changes of pH in soil solution during sorption of copper by aggregates of paddy soil].

Science.gov (United States)

Xu, Hai-Bo; Zhao, Dao-Yuan; Qin, Chao; Li, Yu-Jiao; Dong, Chang-Xun

2014-01-01

Size fractions of soil aggregates in Lake Tai region were collected by the low-energy ultrasonic dispersion and the freeze-desiccation methods. The dissolution of aluminum and changes of pH in soil solution during sorption of Cu2+ and changes of the dissolution of aluminum at different pH in the solution of Cu2+ by aggregates were studied by the equilibrium sorption method. The results showed that in the process of Cu2+ sorption by aggregates, the aluminum was dissoluted and the pH decreased. The elution amount of aluminum and the decrease of pH changed with the sorption of Cu2+, both increasing with the increase of Cu2+ sorption. Under the same conditions, the dissolution of aluminum and the decrease of pH were in the order of coarse silt fraction > silt fraction > sand fraction > clay fraction, which was negatively correlated with the amount of iron oxide, aluminum and organic matter. It suggested that iron oxide, aluminum and organic matters had inhibitory and buffering effect on the aluminum dissolution and the decrease of pH during the sorption of Cu2+.

All-cellulose composites of regenerated cellulose fibres by surface selective dissolution

NARCIS (Netherlands)

Soykeabkaew, N.; Nishino, T.; Peijs, Ton