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Sample records for stability indicating rp-hplc

  1. Stability indicating RP-HPLC method for simultaneous determination of piroxicam and ofloxacin in binary combination.

    PubMed

    John, Peter; Azeem, Waqar; Ashfaq, Muhammad; Khan, Islam Ullah; Razzaq, Syed Naeem

    2015-09-01

    A simple and precise RP-HPLC method was developed for simultaneous determination of piroxicam and ofloxacin in pharmaceutical formulations and human serum. Optimum separations of piroxicam, ofloxacin and stress-induced degradation products were achieved by use of Hypersil BDS C8 column (250 x 4.6mm, 5 ?m). The mobile phase was a mixture of acetonitrile: 0.012M K2HPO4: 0.008M sodium citrate (both buffers mixed and pH adjusted to 2.8) (50:25:25 v/v/v) delivered at flow rate of 1.5 mL min?¹ using DAD at 254 nm. Response was linear function of concentration over the ranges of 70-130 mg mL?¹ for piroxicam and ofloxacin (r² ? 0.999). The method efficiently separated the analytical peaks from degradation products with acceptable tailing and resolution. The developed method was successfully used for concurrent analysis of piroxicam and ofloxacin in pharmaceutical formulations, human serum and in vitro drug interaction studies. PMID:26408892

  2. A validated specific stability-indicating RP-HPLC assay method for the determination of loteprednol etabonate in eye drops.

    PubMed

    Han, Yong K; Segall, Adriana I

    2015-01-01

    A new stability-indicating RP-HPLC assay method was developed and validated for quantitative determination of loteprednol etabonate in bulk drugs and in ophthalmic suspensions in the presence of degradation products generated from forced degradation studies. The system consisted of Agilent Technologies Zorbax Eclipse XDB-Phenyl 5 µm 4.6 × 250 mm, and detection was performed at 244 nm. The mobile phase consisted of water-acetonitrile-acetic acid (34.5:65.0:0.5, v/v/v) run at a flow rate of 1 mL/min and maintained at room temperature. The calibration curve was linear from 30 to 70 µg/mL with r > 0.999. Accuracy (mean recovery 100.78%) and precision were found to be satisfactory. Stress conditions including acid and alkali hydrolysis, water stress, oxidation, photolysis and heat were applied. The degradation products did not interfere with the detection of loteprednol etabonate, thus the method can be considered as a stability-indicating method. The proposed method can be used for quality control assay of loteprednol etabonate in bulk drug and in ophthalmic suspensions and for stability studies as a result of the ability of the method to separate loteprednol etabonate from its degradation products and excipients. PMID:25234383

  3. Stability-Indicating RP-HPLC Method for Simultaneous Estimation of Enrofloxacin and Its Degradation Products in Tablet Dosage Forms

    PubMed Central

    Chakravarthy, V. Ashok; Sailaja, B. B. V.; Kumar, Avvaru Praveen

    2015-01-01

    The present work was the development of a simple, efficient, and reproducible stability-indicating reverse-phase high performance liquid chromatographic (RP-HPLC) method for simultaneous determination enrofloxacin (EFX) and its degradation products including ethylenediamine impurity, desfluoro impurity, ciprofloxacin impurity, chloro impurity, fluoroquinolonic acid impurity, and decarboxylated impurity in tablet dosage forms. The separation of EFX and its degradation products in tablets was carried out on Kromasil C-18 (250 × 4.6?mm, 5??m) column using 0.1% (v/v) TEA in 10?mM KH2PO4 (pH 2.5) buffer and methanol by linear gradient program. Flow rate was 1.0?mL?min?1 with a column temperature of 35°C and detection wavelength was carried out at 278?nm and 254?nm. The forced degradation studies were performed on EFX tablets under acidic, basic, oxidation, thermal, humidity, and photolytic conditions. The degraded products were well resolved from the main active drug and also from known impurities within 65 minutes. The method was validated in terms of specificity, linearity, LOD, LOQ, accuracy, precision, and robustness as per ICH guidelines. The results obtained from the validation experiments prove that the developed method is a stability-indicating method and suitable for routine analysis. PMID:25705547

  4. Stability-Indicating RP-HPLC Method for the Simultaneous Estimation of Doxofylline and Terbutalinesulphate in Pharmaceutical Formulations.

    PubMed

    Samanthula, Gananadhamu; Yadiki, Krishnaveni; Saladi, Shantikumar; Gutala, Sreekanth; Surendranath, K V

    2013-12-01

    An isocratic, stability-indicating, reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the quantitative determination of doxofylline and terbutaline sulphate, used for the treatment of respiratory problems. The chromatographic separation was achieved on a Zorbax-SB Phenyl 250 × 4.6mm × 5 ?m column with the mobile phase consisting of a mixture of 25 mM ammonium acetate (pH 5.0) : acetonitrile (85:15 %v/v) at a flow rate of 1.0 ml/min. The eluate was monitored at 274 nm using a PDA detector. Forced degradation studies were performed on the bulk sample of doxofylline and terbutaline sulphate using acid (0.1N HCl), base (0.1N NaOH), oxidation (10% hydrogen peroxide), photolytic, and thermal degradation conditions. Good resolution was observed between the degradants and analytes. Degradation products resulting from the stress studies did not interfere with the detection of doxofylline and terbutaline sulphate, thus the assay is stability-indicating. The method has the requisite accuracy, selectivity, sensitivity, and precision for the simultaneous estimation of doxofylline and terbutaline sulphate in bulk and pharmaceutical dosage forms. The limit of quantitation and limit of detection were found to be 1.16 ?g/ml and 0.38 ?g/ml for doxofylline, 2.08 ?g/ml and 0.62 ?g/ml for terbutaline sulphate, respectively. PMID:24482767

  5. Stability-Indicating RP-HPLC Method for the Simultaneous Estimation of Doxofylline and Terbutalinesulphate in Pharmaceutical Formulations

    PubMed Central

    Samanthula, Gananadhamu; Yadiki, Krishnaveni; Saladi, Shantikumar; Gutala, Sreekanth; Surendranath, K. V.

    2013-01-01

    An isocratic, stability-indicating, reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the quantitative determination of doxofylline and terbutaline sulphate, used for the treatment of respiratory problems. The chromatographic separation was achieved on a Zorbax-SB Phenyl 250 × 4.6mm × 5 ?m column with the mobile phase consisting of a mixture of 25 mM ammonium acetate (pH 5.0) : acetonitrile (85:15 %v/v) at a flow rate of 1.0 ml/min. The eluate was monitored at 274 nm using a PDA detector. Forced degradation studies were performed on the bulk sample of doxofylline and terbutaline sulphate using acid (0.1N HCl), base (0.1N NaOH), oxidation (10% hydrogen peroxide), photolytic, and thermal degradation conditions. Good resolution was observed between the degradants and analytes. Degradation products resulting from the stress studies did not interfere with the detection of doxofylline and terbutaline sulphate, thus the assay is stability-indicating. The method has the requisite accuracy, selectivity, sensitivity, and precision for the simultaneous estimation of doxofylline and terbutaline sulphate in bulk and pharmaceutical dosage forms. The limit of quantitation and limit of detection were found to be 1.16 ?g/ml and 0.38 ?g/ml for doxofylline, 2.08 ?g/ml and 0.62 ?g/ml for terbutaline sulphate, respectively. PMID:24482767

  6. RP-HPLC stability-indicating assay method for talinolol and characterization of its degradation products.

    PubMed

    Sinha, V R; Ghai, Damanjeet

    2011-01-01

    A reversed-phase high-performance liquid chromatographic method is developed and validated for the quantitative determination of talinolol and to characterize its degradation products. A very good resolution between peaks is achieved using a C18 column at 40°C. The mobile phase comprises of a mixture of acetonitrile and potassium dihydrogen orthophosphate buffer (pH 4.4) in the ratio of 27:73 (v/v). The method is validated with respect to linearity, accuracy, precision, robustness, and forced degradation studies, which further proved the stability indicating power. During the forced degradation studies, talinolol is observed to be labile to hydrolytic stress and thermal stress (in the solution form). However, it is stable to the oxidative, photolytic, and thermal stress (in the solid form). The degraded products formed are investigated by electrospray ionization (ESI), time-of-flight mass spectrometry, nuclear magnetic resonance, and infrared spectroscopy. A possible degradation pathway is outlined based on the results. The method is found to be sensitive with a detection limit of 0.125 ?g/mL and a quantitation limit of 0.378 ?g/mL. The method is also demonstrated to be robust, as it is resistant to small variations of chromatographic variables such as pH, mobile phase composition, flow rate, and column temperature. PMID:22080807

  7. Stability indicating RP-HPLC method for simultaneous determination of atorvastatin and amlodipine from their combination drug products.

    PubMed

    Chaudhari, Bharat Ganeshbhai; Patel, Natvarlal Manilal; Shah, Paresh Bhagvatiprasad

    2007-02-01

    The study describes development and subsequent validation of a stability indicating reverse-phase HPLC method for the simultaneous estimation of atorvastatin (ATV), and amlodipine (AML) from their combination drug product. The proposed RP-HPLC method utilizes a Lichrospher 100 C18, 5 microm, 250 mm x 4.0 mm i.d. column, at ambient temperature, optimum mobile phase consisted of acetonitrile and 50 mM potassium dihydrogen phosphate buffer (60 : 40, v/v), apparent pH adjusted to 3+/-0.1 with 10% phosphoric acid solution, effluent flow rate monitored at 1.0 ml/min, and UV detection at 254 nm. ATV, AML, and their combination drug product were exposed to thermal, photolytic, hydrolytic, and oxidative stress conditions, and the stressed samples were analyzed by proposed method. The method was applied for the in vitro dissolution of marketed combination drug products. The described method was linear over the range of 1-90 microg/ml and 1-80 microg/ml for ATV and AML, respectively. The mean recoveries were 99.76 and 98.12% for ATV and AML, respectively. The intermediate precision data obtained under different experimental setup, the calculated value of coefficient of variation (CV, %) was found to be less than critical value. The limit of detection for ATV and AML were found to be 0.4 and 0.6 mug/ml, respectively and the limit of quantification was 1.0 microg/ml for both drugs. The average percentage drug release was found to be more than 70% within 30 min for both drugs. Chromatographic peak purity data of ATV and AML indicated no co-eluting peaks with the main peaks of drugs which demonstrated the specificity of assay method for their estimation in presence of degradation products. The proposed method can be useful in the quality control and in vitro dissolution of combination drug products. PMID:17268096

  8. Development and Validation of a Novel Stability-Indicating RP-HPLC Method for the Simultaneous Determination of Halometasone, Fusidic Acid, Methylparaben, and Propylparaben in Topical Pharmaceutical Formulation

    PubMed Central

    Goswami, Nishant; Gupta, V. Rama Mohan; Jogia, Hitesh A.

    2013-01-01

    A stability-indicating reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the simultaneous determination of halometasone, fusidic acid, methylparaben, and propylparaben in topical pharmaceutical formulation. The desired chromatographic separation was achieved on an Agilent Zorbax CN (Cyano), 5 ?m (250 × 4.6 mm) column using gradient elution at 240 nm detector wavelength. The optimized mobile phase consisted of a mixture of 0.01 M phosphate buffer and 0.1% orthophosphoric acid, pH-adjusted to 2.5 with an ammonia solution as solvent-A and acetonitrile as solvent-B. The developed method separated halometasone, fusidic acid, methylparaben, and propylparaben in the presence of known impurities/degradation products. The stability-indicating capability was established by forced degradation experiments and separation of known and unknown degradation products. The developed RP-HPLC method was validated according to the International Conference on Harmonization (ICH) guidelines. This validated method was applied for the simultaneous estimation of HM, FA, MP, and PP in commercially available cream samples. Further, the method can be extended for the estimation of HM, FA, MP, and PP in various commercially available dosage forms. PMID:23833716

  9. Development of a Stability-Indicating RP-HPLC Method for the Determination of Rupatadine and its Degradation Products in Solid Oral Dosage Form

    PubMed Central

    Trivedi, Harshal Kanubhai; Patel, Mukesh C.

    2012-01-01

    A simple, sensitive, and reproducible reversed-phase high-performance liquid chromatography (RP-HPLC) method, coupled with a photodiode array detector, was developed for the determination of rupatadine (RUPA) and its related substances in pharmaceutical dosage forms. Chromatographic separation was achieved on the Hypersil BDS (150 x 4.6 mm, 5 ?m) column with a mobile phase containing a gradient mixture of a buffer (acetate buffer pH-6.0) and solvent (methanol). The eluted compounds were monitored at 264 nm for the related substances and assay, the flow rate was 1.0 mL/min, and the column oven temperature was maintained at 50°C. The developed method separated RUPA from its four known and three unknown impurities within 15.0 min. Rupatadine was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal, and photolytic degradation. Rupatadine was found to degrade significantly under oxidative stress conditions, and degrade slightly under acid, base, hydrolytic, thermal, and photolytic stress conditions. All impurities were well-resolved from each other and from the main peak, showing the stability-indicating power of the method. The developed method was validated as per the International Conference on Harmonization (ICH) guidelines. The developed and validated RP-HPLC method is LC-MS compatible and can be explored for the identification of eluted unknown impurities of RUPA. PMID:23264938

  10. A validated specific stability-indicating RP-HPLC assay method for Ambrisentan and its related substances.

    PubMed

    Narayana, M B V; Chandrasekhar, K B; Rao, B M

    2014-09-01

    A validated specific stability-indicating reverse-phase liquid chromatographic method was developed for the quantitative determination of Ambrisentan as well as its related substances in bulk samples, pharmaceutical dosage forms in the presence of degradation products and its related impurities. Forced degradation studies were performed on bulk samples of Ambrisentan as per the ICH-prescribed stress conditions using acid, base, oxidative, thermal stress and photolytic degradation to show the stability-indicating power of the LC method. Significant degradation in acidic, basic stress conditions was observed and no degradation was observed in other stress conditions. The chromatographic method was optimized using the samples generated from the forced degradation studies and the impurity-spiked solution. Good resolution between the peaks corresponds to Ambrisentan-related impurities and degradation products from the analyte were achieved on a SunFire C18 column using a mobile phase consisting of a mixture of potassium dihydrogen orthophosphate at a pH adjusted to 2.5 with ortho-phosphoric acid in water and a mixture of acetonitrile:methanol using a simple linear gradient. The detection was carried out at 225 nm. The limit of detection and the limit of quantification for the Ambrisentan and its related impurities were established. The stressed test solutions were assayed against the qualified working standard of Ambrisentan and the mass balance in each case was between 98.9 and 100.3%, indicating that the developed LC method was stability indicating. Validation of the developed LC method was carried out as per the ICH requirements. The developed method was found to be suitable to check the quality of bulk samples of Ambrisentan at the time of batch release and also during its storage (long-term and accelerated stability). PMID:23926121

  11. New Validated Stability-Indicating Rp-HPLC Method for Simultaneous Estimation of Atorvastatin and Ezetimibe in Human Plasma by Using PDA Detector

    PubMed Central

    Kumar, S. Ashutosh; Debnath, Manidipa; Rao, J.V.L.N. Seshagiri; Sankar, D. Gowri

    2015-01-01

    Purpose: This paper describes a simple, precise and accurate RP-HPLC method for simultaneous estimation of atorvastatin and ezetimibe in plasma. Methods: The chromatographic separation of the drugs were performed on an X-Terra C8 (4.6 x 150 mm, 3.5 mm), with phosphate buffer [pH 3.5 with Ortho Phosphoric Acid] – acetonitrile 40:60 (v/v) as mobile phase. The detection was performed at 235 nm. The flow rate was maintained at 1.2 mL/min. The run time was 8.0 min. Results: The accuracy and reliability of the method was assessed by evaluation of linearity (5-25 µg/mL for both atorvastatin calcium and ezetimibe), precision (intra-day RSD 0.57 % and inter-day RSD 0.02 % for atorvastatin calcium and intra-day RSD 0.56 % and inter-day RSD 0.1 % for ezetimibe), accuracy (100.08- 100.84 % for atorvastatin calcium and 100.56- 101.00 % for ezetimibe), and specificity, in accordance with ICH guidelines. The LLOQ obtained by the proposed method were 1.294 and 1.384 µg/mL for atorvastatin and ezetimibe respectively. Conclusion: Overall the proposed method was found to be suitable and accurate for the quantitative determination in plasma. The method was effectively separated the drug from plasma. PMID:26504761

  12. An RP-HPLC Method for the Stability-Indicating Analysis of Impurities of Both Fusidic Acid and Betamethasone-17-Valerate in a Semi-Solid Pharmaceutical Dosage Form.

    PubMed

    Byrne, Jonathan; Velasco-Torrijos, Trinidad; Reinhardt, Robert

    2015-10-01

    A topical pharmaceutical cream containing the active pharmaceutical ingredients (APIs) betamethasone-17-valerate and fusidic acid has been developed for the treatment of inflammatory skin conditions and associated secondary infections. In this work, a novel stability-indicating RP-HPLC method has been developed for the simultaneous quantitation of impurities of both APIs present in this cream. The HPLC column was a 150 mm × 4.6 mm I.D. YMC-Pack Pro C18 column with 3 µm particles. The column-oven temperature was maintained at 40°C and UV detection at 235 nm was used. A gradient programme was employed at a flow rate of 0.7 mL/min. Mobile phase A comprised of a 16:21:21:42 (v/v/v/v) mixture of methanol, 10 g/L phosphoric acid, HPLC grade water and acetonitrile. Mobile phase B comprised of a 24:5:5:66 (v/v/v/v) mixture of methanol, 10 g/L phosphoric acid, HPLC grade water and acetonitrile. The method has been validated according to current International Conference on Harmonisation (ICH) guidelines and applied during formulation development and stability studies. The procedure has been shown to be stability-indicating for the topical cream. PMID:25896658

  13. LC-MS-MS Characterization of Forced Degradation Products of Fidarestat, a Novel Aldose Reductase Inhibitor: Development and Validation of a Stability-Indicating RP-HPLC Method.

    PubMed

    Talluri, M V N Kumar; Khatoon, Lubna; Kalariya, Pradipbhai D; Chavan, Balasaheb B; Ragampeta, Srinivas

    2015-10-01

    An accurate, precise, robust and selective stability-indicating liquid chromatographic (LC) method has been developed for the monitoring of fidarestat in the presence of its forced degradants. The drug was subjected to hydrolysis (acid, alkali and neutral degradation), oxidation, photolysis and thermal stress conditions. The drug degraded significantly under hydrolytic (basic, acidic and neutral) and oxidative stress conditions, whereas it was found to be stable in photolytic and thermal conditions. The chromatographic separation was achieved on a Grace C18, (250 mm × 4.6 mm × 5 ?m) column using gradient mobile phase system consisting of 10 mM of ammonium acetate buffer at pH 4 and acetonitrile at a flow rate of 1 mL/min with UV detection at 283 nm. The developed method was extended to liquid chromatography quadrupole time-of-flight tandem mass spectrometry (LC-QTOF-MS-MS) for characterization of all the degradation products. A total of five new degradation products were identified and characterized by LC-QTOF-MS-MS. The developed LC method was validated as per ICH guideline Q2 (R1). The proposed method was found to be successively applied for the quality control of fidarestat in bulk drug analysis. PMID:26014964

  14. Validated stability indicating RP-HPLC for quantitation of nitazoxanide in presence of its alkaline degradation products and their characterization by HPLC-tandem mass spectrometry.

    PubMed

    Hegazy, Maha; Kessiba, Amira; El Gindy, Ahmed Emad; Abdelkawy, Mohamed

    2014-10-01

    A simple and sensitive stability indicating HPLC method was developed and validated for quantitative determination of Nitazoxanide (NTZ), a new antiprotozoal drug, in presence of degradation products generated under forced alkaline hydrolysis. Chromatographic separation was achieved on Inertsil C8-3 column (150 × 4.6 mm i.d.) using a mobile phase composed of acetonitrile: 50 mM ammonium acetate buffer (50:50, v/v, pH 5.0 adjusted with acetic acid) at a flow rate of 1 mL/min. Quantification was achieved with UV detection at 298 nm based on relative peak area. The method was linear over the concentration range of 0.8-50 µg/mL (r = 0.9999) with a limit of detection and quantification 0.0410 and 0.1242 µg/mL, respectively. The developed method has the requisite accuracy, selectivity, sensitivity and precision to assay NTZ in presence of its degradation products either in bulk powder or in pharmaceutical formulations. The degradation products were then identified by HPLC-MS/MS analysis using an electrospray ionization source and an ion trap analyzer. PMID:24248557

  15. Identification of Rhodiola species by using RP-HPLC*

    PubMed Central

    Wang, Qiang; Ruan, Xiao; Jin, Zhi-hua; Yan, Qi-chuan; Tu, Shan-jun

    2005-01-01

    An approach was established using RP-HPLC (reversed-phase high-performance liquid chromatography) to identify ten species of Rhodiola, R. coccinea A. Bor, R. junggarica C.Y. Yang et N.R. Cui spn., R. heterodonta A. Bor, R. linearifolia A. Bor, R. pamiro alaiucm A. Bor, R. kaschgarica A. Bor, R. litwinowii A. Bor, R. gelida schrenk, R. rosea L. and R. quadrifide Fisch et Mey collected from the Tianshan Mountains areas of China. Chromatograms of alcohol-soluble proteins, generated from these ten Rhodiola spp. were compared. Each chromatogram of alcohol-soluble proteins came from a single seed of one wild species only. The results showed that when using a Waters Delta Pak. C18, 5 ?m particle size reversed phase column (150 mm×3.9 mm), a linear gradient of 22%–55% solvent B with a flow rate of 1 ml/min and a run time of 67 min, the chromatography gave optimum separation of Rhodiola alcohol-soluble proteins. Chromatogram of each species was different and could be used to identify those species. Cluster analysis of genetic similarity coefficients of 37% to 60% showed a medium degree of genetic diversity among the species in these eco-areas. Cluster analysis showed that the ten species of Rhodiola can be divided into four clusters and yielded the general and unique biochemical markers of these species. RP-HPLC was shown to be a rapid, repeatable and reliable method for Rhodiola species identification and analysis of genetic diversity. PMID:15909330

  16. Development and validation of RP-HPLC method to determine anti-allergic compound in Thai traditional remedy called Benjalokawichien.

    PubMed

    Sakpakdeejaroen, Intouch; Juckmeta, Thana; Itharat, Arunporn

    2014-08-01

    Benjalokawichien (BLW) or Ya-Ha-Rak (HR) is a traditional remedy in the Nationaldrug list of herbal medicinal products AD 2012 of Thailand. For traditional use, BLW is used as antipyretic agent. It also has anti-allergic effect, particularly treating allergic rash. The ethanolic extract of BLW exhibited anti-allergic activity via inhibitory effect against a release ofbeta-hexosaminidase in RBL-2H3 cell line. Pectolinarigenin has been identified as the active compound ofBLW extract. In this study, a reversed-phase high performance liquid chromatography (RP-HPLC) method was developed in order to control quality ofpreparation in three aspects such as chemical fingerprint, quantification and stability of the ethanolic extract. The RP-HPLC was performed with a gradient mobile phase composed of 0.1% ortho phosphoric acid and acetronitrile, and peaks were detected at 331 nm. Based on validation results, this analytical method is precise, accurate and stable for quantitative determination ofpectolinarigenin. The amount ofpectolinarigenin in Benjalokawichien extract determined by this method was 18.50 mg/g ofextract. Therefore, this method could be consideredfor quality control ofBLWextract. PMID:25518297

  17. Cerebral nuclei distribution study of dehydrodiisoeugenol as an anxiogenic agent determined by RP-HPLC.

    PubMed

    Zhang, You-Bo; Zhu, Li-Qiao; Yang, Xiu-Wei

    2013-01-01

    A sensitive RP-HPLC-DAD method was established to quantify dehydrodiisoeugenol (DDIE) in rat cerebral nuclei. The assay procedure involved one-step extraction of DDIE and daidzein, as an internal standard, from rat plasma and various cerebral nuclei with ethyl acetate. Chromatographic separation was performed on a Diamonsil™ ODS C(18) column with methanol-water (81:19, v/v) as a mobile phase. The UV absorbance of the samples was measured at the wavelength of 270nm. The analysis method was proved to be precise and accurate at linearity ranges in plasma and each cerebral nucleus with correlation coefficients of ?0.9971. The results indicated that the method established was successfully applied to cerebral nuclei distribution study of DDIE after intravenous administration at a single dose of 40mg/kg to rat. DDIE showed high concentration in all of cerebral nuclei at 8min, which indicated that DDIE could cross the blood-brain barrier rapidly and might be one of the main bioactive substances of nutmeg. The results provide fundamental data for evaluating the effects of DDIE on the central nervous system and to be developed into an effective anxiogenic agent. PMID:23059843

  18. Preparation of (+)-trans-isoalliin and its isomers by chemical synthesis and RP-HPLC resolution.

    PubMed

    Jayathilaka, Lasanthi; Gupta, Shalini; Huang, Jin-Sheng; Lee, Jenny; Lee, Bao-Shiang

    2014-09-01

    Naturally occurring (+)-trans-isoalliin, (R(C)R(S))-(+)-trans-S-1-propenyl-L-cysteine sulfoxide, is a major cysteine sulfoxide in onion. The importance of producing it synthetically to support further research is very well recognized. The (+)-trans-isoalliin is prepared by chemical synthesis and reversed-phase (RP)-HPLC. First, S-2-propenyl-L-cysteine (deoxyalliin) is formed from L-cysteine and allyl bromide, which is then isomerized to S-1-propenyl-L-cysteine (deoxyisoalliin) by a base-catalyzed reaction. A mixture of cis and trans forms of deoxyisoalliin is formed and separated by RP-HPLC. Oxidation of the trans form of deoxyisoalliin by H2O2 produces a mixture of (-)- and (+)-trans-isoalliin. Finally, RP-HPLC is used successfully in separating (-)- and (+)-trans-isoalliin, and hence, (+)-trans-isoalliin is synthesized for the first time in this study. In addition, the (±) diastereomers of cis-isoalliin are also separated and purified by RP-HPLC. PMID:25187757

  19. Rapid simultaneous determination of marmelosin, umbelliferone and scopoletin from Aegle marmelos fruit by RP-HPLC.

    PubMed

    Shinde, P B; Katekhaye, S D; Mulik, M B; Laddha, K S

    2014-09-01

    The surge of interest in naturally occurring phytochemicals with high therapeutic potential has led to the discovery of many molecules, out of which naturally occuring coumarins such as marmelosin, umbelliferone and scopoletin present in Aegle marmelos (Bael) fruit shows good therapeutic potential. The aim of the present work is to develop and validate Reverse Phase-High Performance Liquid Chromatography (RP-HPLC) method for simultaneous determination of marmelosin, umbelliferone and scopoletin in A. marmelos fruit extracts. The chromatographic separation was performed with isocratic elution of 55:45 (%, v/v) methanol-water containing 0.1 % acetic acid as mobile phase. The method used to analyse the extract of A. marmelos showed good resolution with retention time within 12 min. The relative concentrations of above phytoconstituent were determined in A. marmelos fruits. The method was found to give compact peaks for scopoletin, umbelliferone and marmelosin (Rt of 4.6, 6.5 and 11.3 min respectively) and were linear over the range 5-30 ?g ml(-1) (R(2)?=?0.9655), 2-10 ?g ml(-1) (R(2)?=?0.9964) and 2-10 ?g ml(-1) (R(2)?=?0.9862) respectively. The mean recoveries for marmelosin, umbelliferone and scopoletin at three concentrations were in the range of 98.8-102.9, 98.8-101.1 and 94.2-98.3 % respectively. The relative standard deviation of accuracy, precision and repeatability were within 2 %, indicating the method produced highly reproducible results. Therefore this simple, precise and accurate method enables simultaneous separation of this phytoconstituent and hence can be successfully applied in analysis and routine quality control of herbal material and formulation containing A. marmelos. PMID:25190892

  20. HPTLC and RP-HPLC methods for simultaneous determination of Paracetamol and Pamabrom in presence of their potential impurities.

    PubMed

    Abdelaleem, Eglal A; Naguib, Ibrahim A; Hassan, Eman S; Ali, Nouruddin W

    2015-10-10

    Two chromatgraphic methods were developed for determination of Paracetamol (PCM) and Pamabrom (PAM) in presence of P-aminophenol (PAP) and Theophylline (THEO) as potential impurities of both drugs respectively. First method is HPTLC which depends on separation and quantitation of the studied drugs on aluminum plates pre-coated with silica gel 60 F??? as a stationary phase using chloroform:methanol:ethyl acetate:glacial acetic acid (8:0.8:0.6:0.2, v/v/v/v) as mobile phase followed by densitometric measurement of the bands at 254 nm. Second method is RP-HPLC which comprises separation of the studied drugs on a Phenomenex C8 column by gradient elution using mobile phase consisting of sodium dihydrogen phosphate buffer (0.05 M): methanol:acetonitrile (85:10:5, v/v/v) at a flow rate of 1 mL/min for first 7.5 min and (70:20:10, v/v/v) at a flow rate of 1.5 mL/min for the next 5 min. The proposed methods were successfully applied for determination of the potential impurities of PCM and PAM after resolving them from the pure drugs. The developed methods have been validated and proved to meet the requirements delineated by ICH guidelines with respect to linearity, accuracy, precision, specificity and robustness. The validated methods were successfully applied for determination of the studied drugs in their pharmaceutical formulation. The results were statistically compared to those obtained by the reported RP-HPLC method where no significant difference was found; indicating the ability of proposed methods to be used for routine quality control analysis of these drugs. PMID:26001162

  1. Separation and quantification of water buffalo milk protein fractions and genetic variants by RP-HPLC.

    PubMed

    Bonfatti, Valentina; Giantin, Mery; Rostellato, Roberta; Dacasto, Mauro; Carnier, Paolo

    2013-01-15

    A RP-HPLC method, developed for the separation and quantification of the most common genetic variants of bovine milk proteins, was successfully applied to the analysis of water buffalo milk. All the most common buffalo casein and whey proteins fractions, as well as their genetic variants, were detected and separated simultaneously in 40 min. Purified buffalo proteins were used as calibration standards and a total of 536 individual milk samples were analysed for protein composition. ?(S1)-, ?(S2)-, ??-, and ?-casein were 32.2%, 15.8%, 36.5%, and 15.5%, respectively, of total casein content, whereas content of ?-Lactoglobulin was approximately 1.3 times as high as that of ?-Lactalbumin. The existence of a polymorphism of ?-casein was demonstrated in Mediterranean water buffalo and ?(S1)- and ?-casein genetic variants were successfully detected by RP-HPLC. PMID:23122071

  2. New determination method for sulfonation degree of phthalic anhydride by RP-HPLC.

    PubMed

    Zhu, Lijun; Song, Lechun; Liu, Bin; Zhou, Yulu; Xiang, Yuzhi; Xia, Daohong

    2014-01-01

    A novel method was developed to monitor the reaction process and evaluate the sulfonation level in the sulfonation of phthalic anhydride by reversed-phase high-performance liquid chromatography (RP-HPLC). The product peak was identified in chromatograms through product analysis and by comparing its retention time with that of standard compounds. By comparing the hydrolysis and alcoholysis methods, optimized pretreatment of the sample was found for RP-HPLC. Based on the determined percentages of phthalic anhydride and sulfonated phthalic anhydride in the mixture, the degree of sulfonation was calculated. When the sulfonation degree of phthalic anhydride was in the range of 2.8-71%, the recovery of 97-104% was achieved, and the procedure was rapid and accurate. PMID:23680900

  3. RP-HPLC method development and validation for simultaneous estimation of atorvastatin calcium and pioglitazone hydrochloride in pharmaceutical dosage form.

    PubMed

    Peraman, Ramalingam; Mallikarjuna, Sasikala; Ammineni, Pravalika; Kondreddy, Vinod kumar

    2014-10-01

    A simple, selective, rapid, precise and economical reversed-phase high-performance liquid chromatographic (RP-HPLC) method has been developed for simultaneous estimation of atorvastatin calcium (ATV) and pioglitazone hydrochloride (PIO) from pharmaceutical formulation. The method is carried out on a C8 (25 cm × 4.6 mm i.d., 5 ?m) column with a mobile phase consisting of acetonitrile (ACN):water (pH adjusted to 6.2 using o-phosphoric acid) in the ratio of 45:55 (v/v). The retention time of ATV and PIO is 4.1 and 8.1 min, respectively, with the flow rate of 1 mL/min with diode array detector detection at 232 nm. The linear regression analysis data from the linearity plot showed good linear relationship with a correlation coefficient (R(2)) value for ATV and PIO of 0.9998 and 0.9997 in the concentration range of 10-80 µg mL(-1), respectively. The relative standard deviation for intraday precision has been found to be <2.0%. The method is validated according to the ICH guidelines. The developed method is validated in terms of specificity, selectivity, accuracy, precision, linearity, limit of detection, limit of quantitation and solution stability. The proposed method can be used for simultaneous estimation of these drugs in marketed dosage forms. PMID:24152592

  4. Monitoring seasonal variation of epicatechin and gallic acid in the bark of Saraca asoca using reverse phase high performance liquid chromatography (RP-HPLC) method

    PubMed Central

    Ketkar, Pushkar M.; Nayak, Shraddha U.; Pai, Sandeep R.; Joshi, Rajesh K.

    2015-01-01

    Background: Saraca asoca (Roxb.) Wilde (Fabaceae) is a high valued but vulnerable medicinal plant of Western Ghats region. This plant is mainly known for its use in various gynecological disorders. Objective: The objective of the present study was to investigate seasonal variation of the polyphenolic compounds viz., epicatechin and gallic acid in the bark of S. asoca by using Reverse Phase High Performance Liquid Chromatography-Diode Array Detector (RP-HPLC-DAD) method. Materials and Methods: The bark was collected in six different Ritu (season) viz. Varsha (monsoon), Sharad (autumn), hemant (early winter), Shishir (winter), Vasanta (spring), and Grishma (summer) mentioned in Ayurveda. Results: The RP-HPLC-DAD analysis indicated that levels of epicatechin and gallic acid in the bark of S. asoca vary seasonally. The highest concentration of epicatechin was observed in Shishir Ritu (3315.19 ± 165.76 mg/100g) and gallic acid during Hemant Ritu (211.90 ± 10.60 mg/100 g). Conclusions: In present study, the ability to synthesize and accumulate both the compounds in bark of S. asoca varied greatly throughout the seasons. It was also observed that the compound epicatechin was present abundantly as compared to gallic acid throughout the seasons. PMID:25878461

  5. Role of organic modifier and gradient shape in RP-HPLC separation: analysis of GCSF variants.

    PubMed

    Joshi, Varsha S; Kumar, Vijesh; Rathore, Anurag S

    2015-03-01

    Reversed-phase high-performance liquid chromatography (RP-HPLC) of therapeutic proteins continues to play a significant role in product characterization. This study focuses on two key aspects of HPLC method development, namely the selection of organic modifier and the gradient shape. Separation of granulocyte colony-stimulating factor variants is being used as a case study to illustrate these concepts. The results demonstrate that careful selection of a binary or ternary mixture of solvents with water is an important factor to be considered for achieving the desired resolution of closely related impurities. The resolution of different types of impurities has been shown to be selective toward the choice of eluent along with the ratio in which they are mixed. In addition, this study also presents a systematic approach for selection of gradient shape based on center point solvent composition, initial solvent composition and the steepness of the gradient. The approach proposed in this study was successfully used to reduce the time of analysis from 70 min for the pertinent European Pharmacopeia method to 15 min by using a solvent system with two organic modifiers (acetonitrile and methanol) along with a sigmoidal-shaped gradient. PMID:25637134

  6. Simultaneous estimation of phenolic acids in sea buckthorn (Hippophaë rhamnoides) using RP-HPLC with DAD.

    PubMed

    Arimboor, Ranjith; Kumar, K Sarin; Arumughan, C

    2008-05-12

    A RP-HPLC-DAD method was developed and validated for the simultaneous analysis of nine phenolic acids including gallic acid, protocatechuic acid, p-hydroxybenzoic acid, vanillic acid, salicylic acid, p-coumaric acid, cinnamic acid, caffiec acid and ferulic acid in sea buckthorn (SB) (Hippophaë rhamnoides) berries and leaves. The method was validated in terms of linearity, LOD, precision, accuracy and recovery and found to be satisfactory. Phenolic acid derivatives in anatomical parts of SB berries and leaves were separated into free phenolic acids, phenolic acids bound as esters and phenolic acids bound as glycosides and profiled in HPLC. Berry pulp contained a total of 1068 mg/kg phenolic acids, of which 58.8% was derived from phenolic glycosides. Free phenolic acids and phenolic acid esters constituted 20.0% and 21.2%, respectively, of total phenolic acids in SB berry pulp. The total phenolic acid content in seed kernel (5741 mg/kg) was higher than that in berry pulp and seed coat (Table 2). Phenolic acids liberated from soluble esters constituted the major fraction of phenolic acids (57.3% of total phenolic acids) in seed kernel. 8.4% and 34.3% of total phenolic acids in seed kernel were, respectively contributed by free and phenolic acids liberated from glycosidic bonds. The total soluble phenolic acids content in seed coat (448 mg/kg) was lower than that in seed kernel and pulp (Table 2). Proportion of free phenolic acids in total phenolic acids in seed coat was higher than that in seed kernel and pulp. Phenolic acids bound as esters and glycosides, respectively contributed 49.1% and 20.3% of total phenolic acids in seed coat. The major fraction (approximately 70%) of phenolic acids in SB berries was found to be concentrated in the seeds. Gallic acid was the predominant phenolic acid both in free and bound forms in SB berry parts and leaves. PMID:18194847

  7. Application of different RP-HPLC methods for the determination of the octanol/water partition coefficient of selected tetrachlorobenzyltoluenes.

    PubMed

    Paschke, A; Manz, M; Schüürmann, G

    2001-11-01

    Reversed-phase high-performance liquid chromatography (RP-HPLC) in both, isocratic and gradient elution mode (stationary phase: LiChrospher 100 RP-18; mobile phase: water/methanol or water/acetonitrile) was used for a renewed determination of octanol/water partition coefficients (Kow) of selected tetrachlorobenzyltoluene (TCBT) isomers. Reported Kow values identify this substance class as very hydrophobic but the data are relatively inconsistent. Based on a series of calibration runs with hydrophobic reference substances of different chemical structure at various eluent compositions we tested different approaches for the evaluation of isocratic retention factors (logk) and found substantial differences between the direct calibration procedure at special methanol volume fractions in the mobile phase (0.95-0.80) and the use of retention factors extrapolated to pure water as eluent (logkw). The logKow values obtained for the TCBTs with the latter approach are around 0.5 units higher and closer to literature data. The gradient elution experiments yield slightly better results compared to the isocratic direct calibration procedure, but not as good as the calibration with log kw. In addition, the use of the RP-HPLC retention factors for estimating sorption coefficients (Koc) of TCBT isomers is discussed. PMID:11695590

  8. Stability-Indicating Assay for the Determination of Pentobarbital Sodium in Liquid Formulations

    PubMed Central

    Ajemni, Myriam; Balde, Issa-Bella; Kabiche, Sofiane; Carret, Sandra; Fontan, Jean-Eudes; Cisternino, Salvatore; Schlatter, Joël

    2015-01-01

    A stability-indicating assay by reversed-phase high performance liquid chromatography (RP-HPLC) method was developed for the determination of pentobarbital sodium in oral formulations: a drug used for infant sedation in computed tomography (CT) or magnetic resonance imaging (MRI) scan. The chromatographic separation was achieved on a reversed-phase C18 column, using isocratic elution and a detector set at 214?nm. The optimized mobile phase consisted of a 0.01?M potassium buffer pH 3 and methanol (40?:?60, v/v). The flow rate was 1.0?mL/min and the run time of analysis was 5?min. The linearity of the method was demonstrated in the range of 5 to 250??g/mL pentobarbital sodium solution (r2 = 0.999). The limit of detection and limit of quantification were 2.10 and 3.97??g/mL, respectively. The intraday and interday precisions were less than 2.1%. Accuracy of the method ranged from 99.2 to 101.3%. Stability studies indicate that the drug is stable to sunlight and in aqueous solution. Accelerated pentobarbital sodium breakdown by strong alkaline, acidic, or oxidative stress produced noninterfering peaks. This method allows accurate and reliable determination of pentobarbital sodium for drug stability assay in pharmaceutical studies. PMID:26543481

  9. Quantification of 4'-geranyloxyferulic acid (GOFA) in honey samples of different origin by validated RP-HPLC-UV method.

    PubMed

    Genovese, Salvatore; Taddeo, Vito Alessandro; Fiorito, Serena; Epifano, Francesco

    2016-01-01

    Natural honey has been employed as a nutraceutical agent with benefits and therapeutic promises for humans for many centuries. It has been largely used as food and medicine by all generations, traditions, and civilizations, both ancient and modern. Several chemicals having beneficial effects for human health have been reported as components of natural honey and these include sugars, organic acids, aminoacids, minerals, and vitamins. Also some important phytochemicals have been described and these comprise tannins, flavonoids, terpenes, saponins, and alkaloids. In this note it is described the successful application of a RP HPLC-UV-vis method for the separation and quantification of 4'-geranyloxyferulic acid (GOFA) in four honey samples of different origin. Concentration values showed a great variation between the four samples tested, being chestnut honey the one richest in GOFA (7.87mg/g). The findings described herein represent the first example reported in the literature of the characterization of an oxyprenylated phenylpropanoid in honey. PMID:26421962

  10. Simultaneous determination of chloramphenicol, dexamethasone and naphazoline in ternary and quaternary mixtures by RP-HPLC, derivative and wavelet transforms of UV ratio spectra

    NASA Astrophysics Data System (ADS)

    Hoang, Vu Dang; Hue, Nguyen Thu; Tho, Nguyen Huu; Nguyen, Hue Minh Thi

    2015-03-01

    The application of chemometrics-assisted UV spectrophotometry and RP-HPLC to the simultaneous determination of chloramphenicol, dexamethasone and naphazoline in ternary and quaternary mixtures is presented. The spectrophotometric procedure is based on the first-order derivative and wavelet transforms of ratio spectra using single, double and successive divisors. The ratio spectra were differentiated and smoothed using Savitzky-Golay filter; whereas wavelet transform realized with wavelet functions (i.e. db6, gaus5 and coif3) to obtain highest spectral recoveries. For the RP-HPLC procedure, the separation was achieved on a ZORBAX SB-C18 (150 × 4.6 mm; 5 ?m) column at ambient temperature and the total run time was less than 7 min. A mixture of acetonitrile - 25 mM phosphate buffer pH 3 (27:73, v/v) was used as the mobile phase at a flow rate of 1.0 mL/min and the effluent monitored by measuring absorbance at 220 nm. Calibration graphs were established in the range 20-70 mg/L for chloramphenicol, 6-14 mg/L for dexamethasone and 3-8 mg/L for naphazoline (R2 > 0.990). The RP-HPLC and ratio spectra transformed by a combination of derivative-wavelet algorithms proved to be able to successfully determine all analytes in commercial eye drop formulations without sample matrix interference (mean percent recoveries, 97.4-104.3%).

  11. [Simultaneous determination of benzophenones and xanthone in leaves of Aquilaria sinensis by RP-HPLC-UV].

    PubMed

    Xia, Fang; Lv, Hai-ning; Jiang, Yong; Tu, Peng-fei

    2015-04-01

    This study is to develop a sensitive method by using reversed-phase high performance liquid chromatography coupled with UV detector (HPLC-UV) to simultaneously determine four bioactive compounds, iriflophenone 3-C-beta-D-glucoside, iriflophenone 3,5-C-beta-D-diglucoside, mangiferin, and iriflophenone 2-O-alpha-L-rhamnoside in the leaves of Aquilaria sinensis. An Agilent Zorbax SB-C, column (4, 6 mm x 250 mm, 5 microm) was used, and the gradient elution was performed with mobile phase of 0.1% aqueous phosphoric acid and acetonitrile at a flow rate of 1 mL x min(-1). The detection wavelength was 280 nm, and the column temperature was 25 degrees C. The four marker compounds were well separated with good linearity (R2 > 0.9990), precision, stability and repeatabili y. The-recovery rates were in the range of 98.80%-101.39%. For 15 branch of the leaves, the contents of iriflophenone 3-C-beta-D-gluoside, iriflophenone 3,5-C-beta-D-diglucoside, mangiferin, and iriflophenone 2-O-alpha-L-rhamnoside were between 0.41-14.48, 0.72-3.85, 4.30-29.07, 0.24-5.06 mg, respectivley. This method is precise, accurate and reliable, which provides an efficient way for the quality control of the leaves of A. sinensis. This will promote the comprehensive usage of this plant. PMID:26281559

  12. A RP-HPLC method for quantification of diclofenac sodium released from biological macromolecules.

    PubMed

    Bhattacharya, Shiv Sankar; Banerjee, Subham; Ghosh, Ashoke Kumar; Chattopadhyay, Pronobesh; Verma, Anurag; Ghosh, Amitava

    2013-07-01

    Interpenetrating network (IPN) microbeads of sodium carboxymethyl locust bean gum (SCMLBG) and sodium carboxymethyl cellulose (SCMC) containing diclofenac sodium (DS), a nonsteroidal anti-inflammatory drug, were prepared by single water-in-water (w/w) emulsion gelation process using AlCl3 as cross-linking agent in a complete aqueous environment. Pharmacokinetic study of these IPN microbeads was then carried out by a simple and feasible high-performance liquid chromatographic method with UV detection which was developed and validated for the quantification of diclofenac sodium in rabbit plasma. The chromatographic separation was carried out in a Hypersil BDS, C18 column (250 mm × 4.6 mm; 5 m). The mobile phase was a mixture of acetonitrile and methanol (70:30, v/v) at a flow rate of 1.0 ml/min. The UV detection was set at 276 nm. The extraction recovery of diclofenac sodium in plasma of three quality control (QC) samples was ranged from 81.52% to 95.29%. The calibration curve was linear in the concentration range of 20-1000 ng/ml with the correlation coefficient (r(2)) above 0.9951. The method was specific and sensitive with the limit of quantification of 20 ng/ml. In stability tests, diclofenac sodium in rabbit plasma was stable during storage and assay procedure. PMID:23567284

  13. Simultaneous Estimation of Withaferin A and Z-Guggulsterone in Marketed Formulation by RP-HPLC.

    PubMed

    Agrawal, Poonam; Vegda, Rashmi; Laddha, Kirti

    2015-07-01

    A simple, rapid, precise and accurate high-performance liquid chromatography (HPLC) method was developed for simultaneous estimation of withaferin A and Z-guggulsterone in a polyherbal formulation containing Withania somnifera and Commiphora wightii. The chromatographic separation was achieved on a Purosphere RP-18 column (particle size 5 µm) with a mobile phase consisting of Solvent A (acetonitrile) and Solvent B (water) with the following gradients: 0-7 min, 50% A in B; 7-9 min, 50-80% A in B; 9-20 min, 80% A in B at a flow rate of 1 mL/min and detection at 235 nm. The marker compounds were well separated on the chromatogram within 20 min. The results obtained indicate accuracy and reliability of the developed simultaneous HPLC method for the quantification of withaferin A and Z-guggulsterone. The proposed method was found to be reproducible, specific, precise and accurate for simultaneous estimation of these marker compounds in a combined dosage form. The HPLC method was appropriate and the two markers are well resolved, enabling efficient quantitative analysis of withaferin A and Z-guggulsterone. The method can be successively used for quantitative analysis of these two marker constituents in combination of marketed polyherbal formulation. PMID:25572656

  14. Validation and Uncertainty Estimation of an Ecofriendly and Stability-Indicating HPLC Method for Determination of Diltiazem in Pharmaceutical Preparations

    PubMed Central

    Sadeghi, Fahimeh; Navidpour, Latifeh; Bayat, Sima; Afshar, Minoo

    2013-01-01

    A green, simple, and stability-indicating RP-HPLC method was developed for the determination of diltiazem in topical preparations. The separation was based on a C18 analytical column using a mobile phase consisted of ethanol: phosphoric acid solution (pH = 2.5) (35?:?65, v/v). Column temperature was set at 50°C and quantitation was achieved with UV detection at 240?nm. In forced degradation studies, the drug was subjected to oxidation, hydrolysis, photolysis, and heat. The method was validated for specificity, selectivity, linearity, precision, accuracy, and robustness. The applied procedure was found to be linear in diltiazem concentration range of 0.5–50??g/mL (r2 = 0.9996). Precision was evaluated by replicate analysis in which % relative standard deviation (RSD) values for areas were found below 2.0. The recoveries obtained (99.25%–101.66%) ensured the accuracy of the developed method. The degradation products as well as the pharmaceutical excipients were well resolved from the pure drug. The expanded uncertainty (5.63%) of the method was also estimated from method validation data. Accordingly, the proposed validated and sustainable procedure was proved to be suitable for routine analyzing and stability studies of diltiazem in pharmaceutical preparations. PMID:24163778

  15. Isolation, Characterization, Crystal Structure Elucidation of Two Flavanones and Simultaneous RP-HPLC Determination of Five Major Compounds from Syzygium campanulatum Korth.

    PubMed

    Memon, Abdul Hakeem; Ismail, Zhari; Al-Suede, Fouad Saleih Resq; Aisha, Abdalrahim F A; Hamil, Mohammad Shahrul Ridzuan; Saeed, Mohammed Ali Ahmed; Laghari, Madeeha; Majid, Amin Malik Shah Abdul

    2015-01-01

    Two flavanones named (2S)-7-Hydroxy-5-methoxy-6,8-dimethyl flavanone (1), (S)-5,7-dihydroxy-6,8-dimethyl-flavanone (2), along with known chalcone, namely, (E)-2',4'- dihydroxy-6'-methoxy-3',5'-dimethylchalcone (3) and two triterpenoids, namely, betulinic and ursolic acids (4 and 5), were isolated from the leaves of Syzygium campanulatum Korth (Myrtaceae). The structures of compounds (1 and 2) were determined on the basis of UV-visible, FTIR, NMR spectroscopies and LC-EIMS analytical techniques. Furthermore, new, simple, precise, selective, accurate, highly sensitive, efficient and reproducible RP-HPLC method was developed and validated for the quantitative analysis of the compounds (1-5) from S. campanulatum plants of five different age. RP-HPLC method was validated in terms of specificity, linearity (r2 ? 0.999), precision (2.0% RSD), and recoveries (94.4%-105%). The LOD and LOQ of these compounds ranged from 0.13-0.38 and 0.10-2.23 ?g·mL-1, OPEN ACCESS respectively. Anti-proliferative activity of isolated flavanones (1 and 2) and standardized extract of S. campanulatum was evaluated on human colon cancer (HCT 116) cell line. Compounds (1 and 2) and extract revealed potent and dose-dependent activity with IC50 67.6, 132.9 and 93.4 ?g·mL-1, respectively. To the best of our knowledge, this is the first study on isolation, characterization, X-ray crystallographic analysis of compounds (1 and 2) and simultaneous RP-HPLC determination of five major compounds (1-5) from different age of S. campanulatum plants. PMID:26248073

  16. Isolation, Characterization, and RP-HPLC Estimation of P-Coumaric Acid from Methanolic Extract of Durva Grass (Cynodon dactylon Linn.) (Pers.)

    PubMed Central

    Karthikeyan, Ramadoss; Devadasu, Chapala; Srinivasa Babu, Puttagunta

    2015-01-01

    P-coumaric acid is a nonflavonoid phenolic acid and is a major constituent of the species Cynodon dactylon Linn. (Pers.). In this study isolation of P-coumaric acid was achieved by preparative TLC and the compound thus isolated was characterised by UV, mass, and H1 NMR spectral analysis. An isocratic RP-HPLC method was developed for the estimation of P-coumaric acid from methanolic extracts of durva grass. The chromatographic separations were achieved by RP-C18 column (250?mm?×?4.6?mm, 5??), Shimadzu LC-20AT Prominence liquid chromatograph, and a mobile phase composed of water?:?methanol?:?glacial acetic acid (65?:?34?:?1?v/v). The flow rate was 1.0?mL/min and the analyses of column effluents were performed using UV-visible detector at 310?nm. Retention time of P-coumaric acid was found to be 6.617?min. This method has obeyed linearity over the concentration range of 2–10??g/mL and the regression coefficient obtained from linearity plot for P-coumaric acid was found to be 0.999. RP-HPLC method was validated in pursuance of ICH guidelines. PMID:25788944

  17. Validation of a RP-HPLC-DAD Method for Chamomile (Matricaria recutita) Preparations and Assessment of the Marker, Apigenin-7-glucoside, Safety and Anti-Inflammatory Effect

    PubMed Central

    Miguel, Felipe Galeti; Cavalheiro, Amanda Henriques; Spinola, Nathália Favaretto; Ribeiro, Diego Luis; Barcelos, Gustavo Rafael Mazzaron; Antunes, Lusânia Maria Greggi; Hori, Juliana Issa; Marquele-Oliveira, Franciane; Rocha, Bruno Alves; Berretta, Andresa Aparecida

    2015-01-01

    Chamomile is a medicinal plant, which presents several biological effects, especially the anti-inflammatory effect. One of the compounds related to this effect is apigenin, a flavonoid that is mostly found in its glycosylated form, apigenin-7-glucoside (APG), in natural sources. However, the affectivity and safety of this glycoside have not been well explored for topical application. In this context, the aim of this work was to develop and validate a reversed-phase high-performance liquid chromatography (RP-HPLC-DAD) method to quantify APG in chamomile preparations. Additionally, the safety and the anti-inflammatory potential of this flavonoid were verified. The RP-HPLC-DAD method was developed and validated with linearity at 24.0–36.0??g/mL range (r = 0.9994). Intra- and interday precision (RSD) were 0.27–2.66% and accuracy was 98.27–101.21%. The validated method was applied in the analysis of chamomile flower heads, glycolic extract, and Kamillen cream, supporting the method application in the quality control of chamomile preparations. Furthermore, the APG safety was assessed by MTT cytotoxicity assay and mutagenic protocols and the anti-inflammatory activity was confirmed by a diminished TNF-? production showed by mice macrophages treated with APG following LPS treatment. PMID:26421053

  18. Development and validation of a novel stability-indicating reversed-phase high-performance liquid chromatography method for assay of loratadine and determination of its related compounds.

    PubMed

    Lu, Jun; Wei, Yu-Chien; Markovich, Robert J; Rustum, Abu M

    2010-01-01

    Loratadine is an important active pharmaceutical ingredient used in a wide variety of prescription and over-the-counter products for the treatment and relief of allergy symptoms. A novel stability-indicating gradient ion-pair RP-HPLC method for assay of loratadine and determination of both of its degradation compounds and process impurities has been developed. This method can separate loratadine from its eight structurally related compounds; it can also separate all of the related compounds from each other in less than 20 min. The stability-indicating capability of this method has been demonstrated by analyzing aged stability samples of loratadine. A 15 cm x 4.6 mm id YMC-Pack Pro C18 HPLC column was the primary column and a 15 cm x 4.6 mm id SunFire C18 column has been identified as an alternate (truly equivalent) column for this method. This gradient method uses mobile phases consisting of acetonitrile and an aqueous solution of 10 mM sodium acetate and 5 mM sodium dodecyl sulfate at pH 5.5. The new HPLC method was validated according to International Conference on Harmonization guidelines and proved to be suitable for routine QC use. PMID:20629392

  19. Microwave-assisted efficient extraction of different parts of Hippophae rhamnoides for the comparative evaluation of antioxidant activity and quantification of its phenolic constituents by reverse-phase high-performance liquid chromatography (RP-HPLC).

    PubMed

    Sharma, Upendra K; Sharma, Kapil; Sharma, Nandini; Sharma, Abhishek; Singh, Harsh P; Sinha, Arun K

    2008-01-23

    The outcome of different extraction procedures (microwave, ultrasound, Soxhlet, and maceration) on the antioxidant activity of seeds, leaves, pulp, and fruits of Hippophae rhamnoides (sea buckthorn or SBT) was investigated by two different bioassays: 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) and 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays. The SBT extracts were found to possess strong antioxidant activity measured in terms of TEAC (2.03-182.13 and 6.97-282.75 mg/g) with ABTS and DPPH assays, respectively. In general, the antioxidant capacity of microwave-assisted extracts was found to be significantly higher than those obtained by ultrasound-assisted extraction (UAE) and maceration while being slightly higher than Soxhlet extracts. Further, microwave extracts of seeds were found to possess maximum antioxidant capacity followed by leaves, fruits, and pulp. Also, the chemical composition of extracts, studied in terms of the total phenolic content, was found to be in the range of 1.9-23.5 mg/g Gallic acid equivalent (GAE), which indicates a strong correlation between antioxidant activity and phenolic content present in the SBT. In addition, some of its bioactive phenolic constituents, such as rutin ( 1), quercetin-3- O-galactoside ( 2), quercetin ( 3), myricetin ( 4), kaempferol ( 5), and isorhamnetin ( 6), were also quantified in different extracts by reverse-phase high-performance liquid chromatography (RP-HPLC). PMID:18163559

  20. New Validated RP-HPLC Analytical Method for Simultaneous Estimation of Atorvastatin and Ezetimibe in Bulk Samples as Well in Tablet Dosage Forms by Using PDA Detector.

    PubMed

    Kumar, S Ashutosh; Debnath, Manidipa; Seshagiri Rao, J V L N

    2014-01-01

    This paper describes a new RP-HPLC method for simultaneous quantification of these compounds in the bulk sample drug as well as in tablet dosage forms. The chromatographic separation was performed on an XTerra C8 (4.6 x 250 mm; 5 µm), with phosphate buffer [pH 3.5] and acetonitrile in the ratio of 40:60 (v/v) as mobile phase. The detection was carried out at 240 nm. The accuracy was found to be 99.59% and 98.98% for atorvastatin and ezetimibe respectively. The linearity was 5-25 µg/ml for both the drugs. The intra-day RSD was 0.57% and inter-day RSD was 0.13% for atorvastatin calcium and intra-day RSD was 0.56% and inter-day RSD was 0.09% for ezetimibe. The validation of method was carried out utilizing ICH-guidelines. PMID:25553432

  1. A novel ion-pair RP-HPLC method for simultaneous quantification of naproxen and esomeprazole in pharmaceutical formulations.

    PubMed

    Kayesh, Ruhul; Sultan, Md Zakir

    2015-01-01

    A rapid, sensitive and stability indicating ion-pair reversed-phase high-performance liquid chromatographic method was developed for simultaneous estimation of naproxen (NPX) and esomeprazole (ESP) in pharmaceutical preparations. In our study, this new method was used to overcome the instability problem of ESP during high-performance liquid chromatographic analysis in the presence of acidic drugs such as NPX. The method was validated according to ICH, FDA and USP guidelines with respect to accuracy, precision, specificity, linearity, solution stability, robustness, sensitivity and system suitability. The method was developed by using an isocratic condition of mobile phase comprising buffer [tetrabutylammonium hydroxide (0.0077 M) and n-heptane sulfonic acid-Na salt (0.002 M), pH 7.6], acetonitrile and methanol in a 60 : 20 : 20 v/v/v ratio at a flow rate of 1.5 mL/min over a C-18 (Octadecyl-silica, 5 µm, 250 × 4.6 mm) column at ambient temperature. The recovery for both drugs was found to be >99% which demonstrated the accuracy of this method. Intra- and inter-day precision studies of the new method were less than the maximum allowable limit [% relative standard deviation (RSD) ?2.0 according to FDA]. The method showed linear response with a correlation coefficient (r(2)) value of 0.999 for both drugs. More importantly, ESP was quite stable in diluting solvent and mobile phase in the presence of NPX for >3 days. Therefore, it was found to be an accurate, reproducible, sensitive and highly stability-indicating method and can be successfully applied for routine analysis of simultaneous assay of NPX and ESP in pharmaceutical dosage forms. PMID:25182005

  2. Development and Validation of a Stability-Indicating LC-Method for the Simultaneous Estimation of Levodropropizine, Chloropheniramine, Methylparaben, Propylparaben, and Levodropropizine Impurities

    PubMed Central

    Kumar, Palakurthi Ashok; Raju, Thummala Veera Raghava; Thirupathi, Dongala; Kumar, Ravindra; Shree, Jaya

    2013-01-01

    A simple, fast, and efficient RP-HPLC method has been developed and validated for the simultaneous estimation of Levodropropizine, Chloropheniramine, Methylparaben, Propylparaben, and the quantification of Levodropropizine impurities in the Reswas syrup dosage form. A gradient elution method was used for the separation of all the actives and Levodropropizine impurities by using the X-Bridge C18, 150 mm × 4.6 mm, 3.5 ?m column with a flow rate of 1.0 mL/min and detector wavelength at 223 nm. The mobile phase consisted of a potassium dihydrogen orthophosphate buffer and acetonitrile. All the peaks were symmetrical and well-resolved (resolution was greater than 2.5 for any pair of components) with a shorter run time. The limit of detection for Levodropropizine and its Impurity B was 0.07 ?g/ml & 0.05 ?g/ml, whereas the limit of quantification was 0.19 ?g/ml & 0.15 ?g/ml respectively. The method was validated in terms of precision, accuracy, linearity, robustness, and specificity. Degradation products resulting from the stress studies were well-resolved and did not interfere with the detection of Levodropropizine, Chloropheniramine, Methylparaben, Propylparaben, and Levodropropizine Impurity B, thus the test method is stability-indicating. Validation of the method was carried out as per International Conference on Harmonization (ICH) guidelines. PMID:23641334

  3. Stability-indicating determination of rebamipide in the presence of its acid degradation products.

    PubMed

    Abbas, Samah S; Zaazaa, Hala E; Essam, Hebat Allah M; El-Bardicy, Mohammed G

    2014-01-01

    Four sensitive and precise stability-indicating methods for the determination of rebamipide (REB) in the presence of its acid-degradation products and in a pharmaceutical formulation were developed and validated. Method A used the first derivative of the ratio spectra (1DD) spectrophotometric method by measuring the peak amplitude at 249.4 nm (maximum) and at 259 nm (minimum), and at the total peak amplitude (from 249.4 to 259 nm, 1DD(249.4 + 259 nm)) in the range of 2-14 microg/mL. This method yielded mean recoveries of 99.87 +/- 0.83, 100.04 +/- 0.75, and 100.28 +/- 1.11%, respectively. Method B is a dual wavelength method, which allows the determination of REB in presence of its acid-degradation products by measuring the absorbance difference between 254 and 269 nm within a linearity range of 5-65 microg/mL; it showed a mean recovery of 99.84 +/- 1.06. Method C is a TLC-densitometric procedure in which REB was separated from its degradation products using a developing solution of methanol-chloroform-ammonia (8.5 + 1.5 + 0.5, v/v/v). The quantitative evaluation of REB at 329 nm was linear over the concentration range of 0.50-4.5 microg/band, with a mean recovery of 99.49 +/- 0.99% even in the presence of up to 90% degradation products. Method D is an RP-HPLC procedure. It provided the complete separation of REB from its degradation products on an Xterra C18 column using phosphate buffer (pH 6, 0.01 M)-methanol (1 + 1, v/v) as the mobile phase (UV detection at 254 nm). Recovery was 99.28 +/- 0.78% within the range of 10-190 microg/mL. The selectivity of the proposed methods was checked using laboratory-prepared mixtures. The proposed methods have been successfully applied to the analysis of REB in pharmaceutical dosage forms without interference from other dosage form excipients. PMID:24672862

  4. Sequence-specific retention calculator. Algorithm for peptide retention prediction in ion-pair RP-HPLC: application to 300- and 100-A pore size C18 sorbents.

    PubMed

    Krokhin, Oleg V

    2006-11-15

    Continued development of a new sequence-specific algorithm for peptide retention prediction in RP HPLC is reported. Our discovery of the large effect on the apparent hydrophobicity of N-terminal amino acids produced by the ion-pairing retention mechanism has led to the development of sequence-specific retention calculator (SSRCalc) algorithms. These were optimized for a set of approximately 2000 tryptic peptides confidently identified by off-line microHPLC-MALDI MS (MS/MS) (300-A pore size C18 sorbent, linear water/acetonitrile gradient, and trifluoroacetic acid as ion-pairing modifier). The latest version of the algorithm takes into account amino acid composition, position of the amino acid residues (N- and C-terminal), peptide length, overall hydrophobicity, pI, nearest-neighbor effect of charged side chains (K, R, H), and propensity to form helical structures. A correlation with R2 approximately 0.98 was obtained for the 2000-peptide optimization set. A flexible structure for the SSRC programming code allows easy adaptation to different chromatographic conditions. This was demonstrated by adapting the algorithm (approximately 0.98 R2 value) for a set of approximately 2500 peptides separated on a 100-A pore size C18 column. The SSRCalc algorithm has also been extensively tested for a number of real samples, providing solid support for protein identification and characterization; correlations in the range of 0.95-0.97 R2 value have normally been observed. PMID:17105172

  5. Simultaneous determination of 15 phenolic compounds and caffeine in teas and mate using RP-HPLC/UV detection: method development and optimization of extraction process.

    PubMed

    Bae, In Kyung; Ham, Hyeon Mi; Jeong, Min Hee; Kim, Dong Ho; Kim, Ho Jin

    2015-04-01

    A reversed-phase high performance liquid chromatographic coupled to ultraviolet detection (RP-HPLC/UV) method was developed for simultaneous determination of 15 phenolic compounds and caffeine in TEAS (green tea, oolong tea, black tea and mate). Furthermore, the extraction process of total phenolic contents (TPC) from TEAS were optimized using response surface methodology (RSM) based on a central composite design (CCD) and then applied to extraction of TEAS. The best conditions obtained using the model were as follow: green tea--extraction time of 123 min, extraction temperature of 70 °C and ethanol concentration of 75%, oolong tea--extraction time of 98 min, extraction temperature of 70 °C and ethanol concentration of 69%, black tea--extraction time of 105 min, extraction temperature of 71 °C and ethanol concentration of 63%, and mate--extraction time of 103 min, extraction temperature of 71 °C and ethanol concentration of 61%. Among the extraction methods used in this study, heat-reflux extraction was found to result in the highest values of TPC. The chromatographic peaks of the 16 studied compounds were successfully identified by comparing their retention time and UV spectra with the reference standards. Method validation was performed by means of linearity, sensitivity, selectivity, accuracy and precision. The developed method was found to be simple, specific and reliable and is suited for routine analysis of phenolic compounds and caffeine in TEAS. PMID:25442580

  6. Evaluation of a Propolis Water Extract Using a Reliable RP-HPLC Methodology and In Vitro and In Vivo Efficacy and Safety Characterisation

    PubMed Central

    Rocha, Bruno Alves; Bueno, Paula Carolina Pires; Vaz, Mirela Mara de Oliveira Lima Leite; Nascimento, Andresa Piacezzi; Ferreira, Nathália Ursoli; Moreno, Gabriela de Padua; Rodrigues, Marina Rezende; Costa-Machado, Ana Rita de Mello; Barizon, Edna Aparecida; Campos, Jacqueline Costa Lima; de Oliveira, Pollyanna Francielli; Acésio, Nathália de Oliveira; Martins, Sabrina de Paula Lima; Tavares, Denise Crispim; Berretta, Andresa Aparecida

    2013-01-01

    Since the beginning of propolis research, several groups have studied its antibacterial, antifungal, and antiviral properties. However, most of these studies have only employed propolis ethanolic extract (PEE) leading to little knowledge about the biological activities of propolis water extract (PWE). Based on this, in a previous study, we demonstrated the anti-inflammatory and immunomodulatory activities of PWE. In order to better understand the equilibrium between effectiveness and toxicity, which is essential for a new medicine, the characteristics of PWE were analyzed. We developed and validated an RP-HPLC method to chemically characterize PWE and PEE and evaluated the in vitro antioxidant/antimicrobial activity for both extracts and the safety of PWE via determining genotoxic potential using in vitro and in vivo mammalian micronucleus assays. We have concluded that the proposed analytical methodology was reliable, and both extracts showed similar chemical composition. The extracts presented antioxidant and antimicrobial effects, while PWE demonstrated higher antioxidant activity and more efficacious for the most of the microorganisms tested than PEE. Finally, PWE was shown to be safe using micronucleus assays. PMID:23710228

  7. Ionic liquid-based dispersive liquid-liquid microextraction followed by RP-HPLC determination of saquinavir in rat serum: application to pharmacokinetics.

    PubMed

    Ramisetti, Nageswara Rao; Nimmu, Narendra Varma; Challa, Gangu Naidu

    2014-12-01

    An ionic liquid-based dispersive liquid-liquid microextraction followed by RP-HPLC determination of the most commonly prescribed protease inhibitor, saquinavir, in rat plasma was developed and validated. The effects of different ionic liquids, dispersive solvents, extractant/disperser ratio and salt concentration on sample recovery and enrichment were studied. Among the ionic liquids investigated, 1-butyl-3-methylimidazolium hexafluorophosphate was found to be most effective for extraction of saquinavir from rat serum. The recovery was found to be 95% at an extractant/disperser ratio of 0.43 using 1-butyl-3-methylimidazolium hexafluorophosphate and methanol as extraction and dispersive solvents. The recovery was further enhanced to 99.5% by addition of 5.0% NaCl. A threefold enhancement in detection and quantification limits was achieved, at 0.01 and 0.03 µg/mL, compared with the conventional protein precipitation method. A linear relationship was observed in the range of 0.035-10.0 µg/mL with a correlation coefficient (r(2) ) of 0.9996. The method was validated and applied to study pharmacokinetics of saquinavir in rat serum. PMID:24944096

  8. Simultaneous determination of fangchinoline and tetrandrine in Stephania tetrandra S. Moore by using 1-alkyl-3-methylimidazolium-based ionic liquids as the RP-HPLC mobile phase additives.

    PubMed

    Tang, Yan; Sun, Ailing; Liu, Renmin; Zhang, Yongqing

    2013-03-12

    A reversed phase high performance liquid chromatography (RP-HPLC) method for simultaneous determination of fangchinoline (FAN) and tetrandrine (TET) in Stephania tetrandra S. Moore was established by using 1-hexyl-3-methylimidazolium tetrafluoroborate as the mobile phase additives in this paper. Four types of 1-alkyl-3-methylimidazolium-based ionic liquids (ILs) were used as additives of the mobile phase to separate FAN and TET by RP-HPLC. The effects of the length of the alkyl group on the imidazolium ring and its counterion, the concentrations of IL and the pH of the mobile phase, which influenced the chromatographic behaviors of FAN and TET, were investigated in detail. The linearity, sensitivity, accuracy and repeatability of the proposed method were also investigated. The probable mechanism of the separation with ILs as the mobile phase additives was explored and discussed. PMID:23452799

  9. Chemometrics-Assisted UV Spectrophotometric and RP-HPLC Methods for the Simultaneous Determination of Tolperisone Hydrochloride and Diclofenac Sodium in their Combined Pharmaceutical Formulation

    PubMed Central

    Gohel, Nikunj Rameshbhai; Patel, Bhavin Kiritbhai; Parmar, Vijaykumar Kunvarji

    2013-01-01

    Chemometrics-assisted UV spectrophotometric and RP-HPLC methods are presented for the simultaneous determination of tolperisone hydrochloride (TOL) and diclofenac sodium (DIC) from their combined pharmaceutical dosage form. Chemometric methods are based on principal component regression and partial least-square regression models. Two sets of standard mixtures, calibration sets, and validation sets were prepared. Both models were optimized to quantify each drug in the mixture using the information included in the UV absorption spectra of the appropriate solution in the range 241–290 nm with the intervals ? = 1 nm at 50 wavelengths. The optimized models were successfully applied to the simultaneous determination of these drugs in synthetic mixture and pharmaceutical formulation. In addition, an HPLC method was developed using a reversed-phase C18 column at ambient temperature with a mobile phase consisting of methanol:acetonitrile:water (60:30:10 v/v/v), pH-adjusted to 3.0, with UV detection at 275 nm. The methods were validated in terms of linearity, accuracy, precision, sensitivity, specificity, and robustness in the range of 3–30 ?g/mL for TOL and 1–10 ?g/mL for DIC. The robustness of the HPLC method was tested using an experimental design approach. The developed HPLC method, and the PCR and PLS models were used to determine the amount of TOL and DIC in tablets. The data obtained from the PCR and PLS models were not significantly different from those obtained from the HPLC method at 95% confidence limit. PMID:24482768

  10. Identification and optimization of parameters for the semi-continuous production of garbage enzyme from pre-consumer organic waste by green RP-HPLC method.

    PubMed

    Arun, C; Sivashanmugam, P

    2015-10-01

    Reuse and management of organic solid waste, reduce the environmental impact on human health and increase the economic status by generating valuable products for current and novel applications. Garbage enzyme is one such product produced from fermentation of organic solid waste and it can be used as liquid fertilizer, antimicrobial agents, treatment of domestic wastewater, municipal and industrial sludge treatment, etc. The semi-continuous production of garbage enzyme in large quantity at minimal time period and at lesser cost is needed to cater for treatment of increasing quantities of industrial waste activated sludge. This necessitates a parameter for monitoring and control for the scaling up of current process on semi-continuous basis. In the present study a RP-HPLC (Reversed Phase-High Performance Liquid Chromatography) method is used for quantification of standard organic acid at optimized condition 30°C column oven temperature, pH 2.7, and 0.7 ml/min flow rate of the mobile phase (potassium dihydrogen phosphate in water) at 50mM concentration. The garbage enzyme solution collected in 15, 30, 45, 60, 75 and 90 days were used as sample to determine the concentration of organic acid. Among these, 90th day sample showed the maximum concentration of 78.14 g/l of acetic acid in garbage enzyme, whereas other organic acids concentration got decreased when compare to the 15th day sample. This result confirms that the matured garbage enzyme contains a higher concentration of acetic acid and thus it can be used as a monitoring parameter for semi-continuous production of garbage enzyme in large scale. PMID:26205805

  11. Sensitivity of stability indices to dealerting

    SciTech Connect

    Canavan, G.H.

    1998-03-01

    It is reported that more than 100 former or current heads of state and civilian leaders from around the world, including ex-presidents Jimmy Carter and Mikhail Gorbachev, have signed a statement that calls for removing nuclear weapons from alert status and other measures aimed at the eventual elimination of atomic arsenals--reflecting mounting support for the cause of nuclear bolition. This note uses stability analysis derived from current US and Russian analyses to study the impact of such dealerting on stability, indicating that it could be negative. Dealerting forces removes them from first and second strikes for as long as they are dealerted. If they are dealerted for periods long compared to those involved in the evaluation of first strike stability, dealerting has the same effect as permanent arms reductions, it subtracts them from first and second strikes. Thus, it is conceptually a way of implementing such reductions on an accelerated scale. Dealerting strategic forces has been posited as a stabilizing step towards their abolition. Previous reports have shown that planned START reductions will reduce stability indices by about a factor of two. Dealerting would hasten those reductions. They would also raise the possibility that one side could realert faster than the other. If so, the remobilized forces could be used to damage limit, which would reduce his first strike cost and stability index. The impact of complete demobilization of SSBNs would be an order of magnitude reduction in the overall stability index, to a level set by alert ICBMs. Generally, it would be preferable to maintain any existing strategic forces at the highest level of alert to minimize this effect and to concentrate instead on decreasing their total number.

  12. Validation of RP-HPLC Method and Stress Degradation for the Combination of Metformin HCl, Atorvastatin Calcium and Glimepiride: Application to Nanoparticles.

    PubMed

    Gite, Sandip; Patravale, Vandana

    2015-11-01

    A stability-indicating high-performance liquid chromatography (HPLC) procedure was developed for the determination of metformin HCl (MTH), atorvastatin calcium (AC) and glimepiride (GP) in combination and their main degradation products. The separation and quantization were achieved on a 5-µm Qualisil gold, C18 column (4.6 mm × 250 mm). The mobile phase selected was phosphate buffer (pH 2.9)-organic phase in proportion of 70:30. Organic phase consisted of methanol-acetonitrile (90:10) at a flow rate of 1 mL/min and detection of analytes was carried out at 230 nm. The method exhibited good linearity over the range of 10-60 µg/mL for MTH, 2-20 µg/mL for AC and 5-30 µg/mL for GP. Square of the correlation coefficients was found to be >0.999. Various stress degradation studies were carried out in combination as per International Conference of Harmonization (ICH) guidelines for 4 h. The recovery and precision were determined in terms of intraday and interday precisions and expressed as relative standard deviations. These were <1 and <2%, respectively. Finally, the applicability of the method was evaluated in nanoparticle analysis of MTH, AC and GP as well as in stability studies of nanoformulation. PMID:26071607

  13. Development of New Method for Simultaneous Analysis of Piracetam and Levetiracetam in Pharmaceuticals and Biological Fluids: Application in Stability Studies

    PubMed Central

    Siddiqui, Farhan Ahmed; Sher, Nawab; Shafi, Nighat; Wafa Sial, Alisha; Ahmad, Mansoor; Mehjebeen

    2014-01-01

    RP-HPLC ultraviolet detection simultaneous quantification of piracetam and levetiracetam has been developed and validated. The chromatography was obtained on a Nucleosil C18 column of 25?cm × 0.46?cm, 10??m, dimension. The mobile phase was a (70?:?30?v/v) mixture of 0.1?g/L of triethylamine and acetonitrile. Smooth flow of mobile phase at 1?mL/min was set and 205?nm wavelength was selected. Results were evaluated through statistical parameters which qualify the method reproducibility and selectivity for the quantification of piracetam, levetiracetam, and their impurities hence proving stability-indicating properties. The proposed method is significantly important, permitting the separation of the main constituent piracetam from levetiracetam. Linear behavior was observed between 20?ng/mL and 10000?ng/mL for both drugs. The proposed method was checked in bulk drugs, dosage formulations, physiological condition, and clinical investigations and excellent outcome was witnessed. PMID:25114921

  14. Development and validation of a novel stability-indicating HPLC method for the quantitative determination of eleven related substances in ezetimibe drug substance and drug product.

    PubMed

    Luo, Zhiqiang; Deng, Zhongqing; Liu, Yang; Wang, Guopeng; Yang, Wenning; Hou, Chengbo; Tang, Minming; Yang, Ruirui; Zhou, Huaming

    2015-07-01

    Ezetimibe is a novel lipid-lowering agent that inhibits intestinal absorption of dietary and biliary cholesterol. In the present work, a simple, sensitive and reproducible gradient reverse phase high performance liquid chromatographic (RP-HPLC) method for separation and determination of the related substances of ezetimibe was developed and validated. Eleven potential process-related impurities (starting materials, (3S,4S,3'S)-isomer, degradants and byproducts) were identified in the crude samples. Tentative structures for all the impurities were assigned primarily based on comparison of their retention time and mass spectrometric data with that of available standards and references. This method can be applied to routine analysis in quality control of both bulk drugs and commercial tablets. Separation of all these compounds was performed on a Phenomenex Luna Phenyl-Hexyl (100mm×4.6mm, 5?m) analytical column. The mobile phase-A consists of acetonitrile-water (pH adjusted to 4.0 with phosphoric acid)-methanol at 15:75:10 (v/v/v), and mobile phase-B contains acetonitrile. The eluted compounds were monitored at 210nm. Ezetimibe was subjected to hydrolytic, acid, base, oxidative, photolytic and thermal stress conditions as per ICH serves to generate degradation products that can be used as a worst case to assess the analytical method performance. The drug showed extensive degradation in thermal, acid, oxidative, base and hydrolytic stress conditions, while it was stable to photolytic degradation conditions. The main degradation product formed under thermal, acid, oxidative, base and hydrolytic stress conditions corresponding to (2R,3R,6S)-N, 6-bis(4-fluorophenyl)-2-(4-hydroxyphenyl)-oxane-3-carboxamide (Ezetimibe tetrahydropyran impurity) was characterized by LC-MS/MS analysis. The degradation products were well resolved from the main peak and its impurities, thus proved the stability-indicating power of the method. The developed method was validated as per international conference on harmonization (ICH) guidelines with respect to specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, precision and robustness. PMID:25882410

  15. Simultaneous determination of phenolic acids and flavonoids in rice using solid-phase extraction and RP-HPLC with photodiode array detection.

    PubMed

    Irakli, Maria N; Samanidou, Victoria F; Biliaderis, Costas G; Papadoyannis, Ioannis N

    2012-07-01

    An analytical method based on an optimized solid-phase extraction procedure and followed by high-performance liquid chromatography (HPLC) separation with diode array detection was developed and validated for the simultaneous determination of phenolic acids (gallic, protocatechuic, 4-hydroxy-benzoic, vanillic, caffeic, syringic, p-coumaric, ferulic, sinapic, and cinnamic acids), flavanols (catechin and epicatechin), flavonols (myricetin, quercetin, kaempferol, quercetin-3-O-glucoside, hyperoside, and rutin), flavones (luteolin and apigenin) and flavanones (naringenin and hesperidin) in rice flour (Oryza sativa L.). Chromatographic separation was carried out on a PerfectSil Target ODS-3 (250 mm × 4.6 mm, 3 ?m) column at temperature 25°C using a mobile phase, consisting of 0.5% (v/v) acetic acid in water, methanol, and acetonitrile at a flow rate 1 mL min(-1) , under gradient elution conditions. Application of optimum extraction conditions, elaborated on both Lichrolut C(18) and Oasis HLB cartridges, have led to extraction of phenolic acids and flavonoids from rice flour with mean recoveries 84.3-113.0%. The developed method was validated in terms of linearity, accuracy, precision, stability, and sensitivity. Repeatability (n = 5) and inter-day precision (n = 4) revealed relative standard deviation (RSD) <13%. The optimized method was successfully applied to the analysis of phenolic acids and flavonoids in pigmented (red and black rice) and non-pigmented rice (brown rice) samples. PMID:22761138

  16. Quantitative and Chemical Fingerprint Analysis for the Quality Evaluation of Receptaculum Nelumbinis by RP-HPLC Coupled with Hierarchical Clustering Analysis

    PubMed Central

    Wu, Yan-Bin; Zheng, Li-Jun; Yi, Jun; Wu, Jian-Guo; Chen, Ti-Qiang; Wu, Jin-Zhong

    2013-01-01

    A simple and reliable method of high-performance liquid chromatography with photodiode array detection (HPLC-DAD) was developed to evaluate the quality of Receptaculum Nelumbinis (dried receptacle of Nelumbo nucifera) through establishing chromatographic fingerprint and simultaneous determination of five flavonol glycosides, including hyperoside, isoquercitrin, quercetin-3-O-?-d-glucuronide, isorhamnetin-3-O-?-d-galactoside and syringetin-3-O-?-d-glucoside. In quantitative analysis, the five components showed good regression (R > 0.9998) within linear ranges, and their recoveries were in the range of 98.31%–100.32%. In the chromatographic fingerprint, twelve peaks were selected as the characteristic peaks to assess the similarities of different samples collected from different origins in China according to the State Food and Drug Administration (SFDA) requirements. Furthermore, hierarchical cluster analysis (HCA) was also applied to evaluate the variation of chemical components among different sources of Receptaculum Nelumbinis in China. This study indicated that the combination of quantitative and chromatographic fingerprint analysis can be readily utilized as a quality control method for Receptaculum Nelumbinis and its related traditional Chinese medicinal preparations. PMID:23337200

  17. Stability Indices derived from Atmospheric Measurements on a Cable Car

    NASA Astrophysics Data System (ADS)

    Herma, F.; Seidel, J.; Bárdossy, A.

    2012-04-01

    Stability indices are meteorological parameters to describe vertical atmospheric layering and therefore it is possible to predict convective events such as thunderstorms. Commonly, weather balloons with radiosondes are used for the analysis of vertical atmospheric layering. These weather balloons reach high altitudes and atmospheric layering can be determined for the entire troposphere. On the other hand, these balloon ascents are expensive, require the appropriate equipment and permissions and cannot be conducted several times a day on an operational basis. Due to the limitations of the application of weather balloons the unconventional idea came up to equip a cable car with meteorological instruments for vertical profile measurements. To some extent the meteorological instruments had to be customized to the particular requirements and data are transmitted via GSM. The investigated area is a small alpine catchment which is prone to flash floods and thus a reliable forecast for such floods mostly caused by convective rainfall events is important. Therefore the purpose of this contribution is to proof if a cable car can be used for measuring continuous data during the operating hours and whether it is possible to derive reliable conclusions about the stability in the lower troposphere. Several stability indices (e.g. Lifted-, Showalter-, Boyden- and Convective-Index) were investigated. Indices which are calculated on the basis of the "Lifted Parcel Theory" were tested with different approaches to determine the most unstable parcel and therefore the initial values of the required parameters. The derived indices were flagged in active (thunderstorms) and non-active (no thunderstorms) cases. The classification results from available lightning maps in this region. Threshold values were established to distinguish stable, potential indifferent and unstable atmospheric conditions. On the basis of this division pre-warnings for the occurrence of thunderstorms are declared. The verification of the quality of these predictions is done by a skill score statistic.

  18. Voltage stability and controllability indices for multimachine power systems

    SciTech Connect

    Vournas, C.D.

    1995-08-01

    This paper presents a voltage stability index (VSI) and a voltage controllability index (VCI), related to the eigenvalues of mxm matrices in a multimachine power system made up of m synchronous generators and a number of infinite buses. System loads can have an arbitrary voltage sensitivity described by generalized voltage exponents. These nonlinear loads are linearized around an operating point and incorporated into a modified admittance matrix, which is subsequently reduced to the generator terminals using an efficient algorithm and sparsity techniques. The indices proposed are tested in a practical system and it is demonstrated that they provide a timely warning during a sequence of events leading to voltage collapse.

  19. Preliminary study on the potential utility of GFP as a biosensor for drug stability in parenteral solutions.

    PubMed

    dos Santos, Carolina Alves; Mazzola, Priscila Gava; Silva, Pedro Henrique Soares; Cholewa, Olivia; Penna, Thereza Christina Vessoni

    2007-01-01

    In the health care setting, drugs added to large volume parenteral solutions (LVPS) are routinely administered to improve therapeutic effects and provide a faster clinical response. The development of analytical techniques that permit the detection of incompatibilities between drugs and parenteral solutions is necessary to guarantee their correct association with minimum adverse effects. Green fluorescent protein (GFP) has been used as a biological indicator of sterilization and disinfection processes because it exhibits a high thermal stability and is easily detected using UV light and spectrofluorometry. The response of GFP structure and/or protonation state to physicochemical changes in the solution favors its potential use as a biosensor for drug stability in parenteral solutions. The stability of the diuretic drugs furosemide and aminophylline, individually or combined, added to parenteral solutions of 20% mannitol and 0.9% NaCl was monitored by absorbance and RP-HPLC immediately and after 20 h of storage at room temperature, with and without 1 h exposure to a strong oxidant, H2O2. Changes in GFP fluorescence intensity were evaluated under the same conditions for purified GFP added to aliquots of the drug/LVPS solutions. Results show that GFP fluorescence intensity was proportional to the loss in drug stability over time and thus may potentially be added to a lot sample of a drug/parenteral solution as an immediate on-site test for defective product. PMID:17567040

  20. Development of Stability-Indicating Methods for Cefquinome Sulphate

    PubMed Central

    Shantier, Shaza W.; Gadkariem, Elrasheed A.; Adam, Mohamed O.; Mohamed, Magdi A.

    2013-01-01

    The degradation behavior of cefquinome sulphate in alkaline medium at different temperatures was investigated using both first derivative spectrophotometric and HPLC methods. The drug degradation was found to be pH and temperature dependant. The pH-rate profile indicated a first order dependence of Kobs on [OH-] at pHs ranging between 9 and 11. Arrhenius plot obtained at pH 10 was linear between 65° and 100°C. The estimated activation energy of the hydrolysis was found to be 21.1 kcal mol-1. Stability-indicating thin-layer chromatographic method for the separation of the drug and its alkaline hydrolysis product has been developed. PMID:24170991

  1. A Review of Voltage Stability Assessment Techniques with an Improved Voltage Stability Indicator

    NASA Astrophysics Data System (ADS)

    Danish, Mir Sayed Shah; Yona, Atsushi; Senjyu, Tomonobu

    2015-04-01

    A blackout can take place in entire power system or a part of the system due to extreme voltage instability (voltage collapse) that can appear abruptly. Instability prediction and continuous monitoring of the power system performance is, therefore, known exigent. This paper is conducted with a broad overview of the voltage stability indices, which are previously studied in the literature, and have the same foundation during their formulation. Afterward, an improved voltage stability indicator is introduced as a result of the multi-criteria integration and enhancement of the original indices by employing linear algebra methods. It is found that the proposed algorithm can overcome on the probable limitations from calculating point view. Then comparative analysis of the indices is presented in order to reach a unique consensus about the typical techniques of modal analysis (sensitivity, eigenvalue, right eigenvectors, and bus participation factor) as a precise algorithm. Finally, the IEEE 14-bus, and 30-bus test systems are selected to verify the algorithm, and compare the performance of the improved indicator approach with the existing indices.

  2. Sensitivity Analysis of Dynamic Stability Indicators in Power Systems

    SciTech Connect

    Nguyen, Tony B.; Pai, M. A.

    2006-01-01

    Real time stability evaluation and preventive scheduling in power systems offers many challenges in a stressed power system. Through fast simulation of contingencies in real time it is possible to extract suitable information from the data and develop reliable metrics or indices to evaluate proximity of the system to an unstable condition. In this chapter we review the recent applications of the trajectory sensitivity analysis (TSA) technique in developing such indicators. Trajectory sensitivities can be used to compute critical parameters such as clearing time of circuit breakers, tie line flow, etc. in a power system by developing suitable norms for ease of interpretation. Alternatively it can be used along with the notion of Principal Singular Surfaces (PSS) to detect mode of instability (MOI). The TSA technique has the advantage that model complexity is not a limitation and the sensitivities are computed numerically. Suitable metrics are developed from these sensitivities. In addition to computing critical parameters, the TSA technique can be extended to do preventive rescheduling. A brief discussion of other applications of TSA is included as well as future areas of research.

  3. Stabilities of neutral and basic esters of bendamustine in plasma compared to the parent compound: kinetic investigations by HPLC.

    PubMed

    Huber, S; Antoni, F; Schickaneder, C; Schickaneder, H; Bernhardt, G; Buschauer, A

    2015-02-01

    Esters of the cytostatic bendamustine (1), previously demonstrated to be much more potent than the parent compound as antiproliferative agents in vitro, were investigated for stability in buffer and plasma, as well as against porcine liver esterase in the presence of different amounts of albumin using a validated RP-HPLC method with fluorescence detection. The hydrolysis of the nitrogen mustard moiety was retarded (for 1: approximately 130 vs. 11 min) in the presence of plasma proteins. For the derivatives, both cleavage of ester and nitrogen mustard moieties were analyzed. Enzymatic hydrolysis was very fast in the case of 2-pyrrolidino-, 2-piperidino- and 2-(4-methylpiperazino)-ethyl esters, whereas methyl, ethyl, morpholinoethyl and branched 2-pyrrolidinoethyl esters were considerably more stable (half-lives between 41 and 116 min, compared to <5 min). Inhibition by physostigmine indicated unspecific cholinesterases to be involved in the rapid ester cleavage. Due to lower protein content and higher enzymatic activity in murine compared to human plasma, reduced stability of all investigated esters in mouse plasma (t½<2 min) has to be taken into account with respect to the design of animal studies. PMID:25499654

  4. Ratio manipulating spectrophotometry versus chemometry as stability indicating methods for cefquinome sulfate determination

    NASA Astrophysics Data System (ADS)

    Yehia, Ali M.; Arafa, Reham M.; Abbas, Samah S.; Amer, Sawsan M.

    2016-01-01

    Spectral resolution of cefquinome sulfate (CFQ) in the presence of its degradation products was studied. Three selective, accurate and rapid spectrophotometric methods were performed for the determination of CFQ in the presence of either its hydrolytic, oxidative or photo-degradation products. The proposed ratio difference, derivative ratio and mean centering are ratio manipulating spectrophotometric methods that were satisfactorily applied for selective determination of CFQ within linear range of 5.0-40.0 ?g mL- 1. Concentration Residuals Augmented Classical Least Squares was applied and evaluated for the determination of the cited drug in the presence of its all degradation products. Traditional Partial Least Squares regression was also applied and benchmarked against the proposed advanced multivariate calibration. Experimentally designed 25 synthetic mixtures of three factors at five levels were used to calibrate and validate the multivariate models. Advanced chemometrics succeeded in quantitative and qualitative analyses of CFQ along with its hydrolytic, oxidative and photo-degradation products. The proposed methods were applied successfully for different pharmaceutical formulations analyses. These developed methods were simple and cost-effective compared with the manufacturer's RP-HPLC method.

  5. Ratio manipulating spectrophotometry versus chemometry as stability indicating methods for cefquinome sulfate determination.

    PubMed

    Yehia, Ali M; Arafa, Reham M; Abbas, Samah S; Amer, Sawsan M

    2016-01-15

    Spectral resolution of cefquinome sulfate (CFQ) in the presence of its degradation products was studied. Three selective, accurate and rapid spectrophotometric methods were performed for the determination of CFQ in the presence of either its hydrolytic, oxidative or photo-degradation products. The proposed ratio difference, derivative ratio and mean centering are ratio manipulating spectrophotometric methods that were satisfactorily applied for selective determination of CFQ within linear range of 5.0-40.0?gmL(-1). Concentration Residuals Augmented Classical Least Squares was applied and evaluated for the determination of the cited drug in the presence of its all degradation products. Traditional Partial Least Squares regression was also applied and benchmarked against the proposed advanced multivariate calibration. Experimentally designed 25 synthetic mixtures of three factors at five levels were used to calibrate and validate the multivariate models. Advanced chemometrics succeeded in quantitative and qualitative analyses of CFQ along with its hydrolytic, oxidative and photo-degradation products. The proposed methods were applied successfully for different pharmaceutical formulations analyses. These developed methods were simple and cost-effective compared with the manufacturer's RP-HPLC method. PMID:26318697

  6. Environmental stability of PAH source indices in pyrogenic tars

    SciTech Connect

    Uhler, A.D.; Emsbo-Mattingly, S.D.

    2006-04-15

    Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants found in soil, sediments, and airborne particulates. The majority of PAHs found in modern soils and sediments arise from myriad anthropogenic petrogenic and pyrogenic sources. Tars and tar products such as creosote produced from the industrial pyrolysis of coal or oil at former manufactured gas plants (MGPs) or in coking retorts are viscous, oily substances that contain significant concentrations of PAH, usually in excess of 30% w/w. Pyrogenic tars and tar products have unique PAH patterns (source signatures) that are a function of their industrial production. Among pyrogenic materials, certain diagnostic ratios of environmentally recalcitrant 4-, 5- and 6-ring PAHs have been identified as useful environmental markers for tracking the signature of tars and petroleum in the environment. The use of selected PAH source ratios is based on the concept that PAHs with similar properties (i.e., molecular weight, partial pressure, solubility, partition coefficients, and biotic/abiotic degradation) will weather at similar rates in the environment thereby yielding stable ratios. The stability of more than 30 high molecular weight PAH ratios is evaluated during controlled studies of tar evaporation and aerobic biodegradation. The starting materials in these experiments consisted of relatively unweathered tars derived from coal and petroleum, respectively. The PAH ratios from these laboratory studies are compared to those measured in PAH residues found in tar-contaminated soils at a former MGP that operated with a carburetted water gas process.

  7. Interaction of native alpha-cyclodextrin, beta-cyclodextrin and gamma-cyclodextrin and their hydroxypropyl derivatives with selected organic low molecular mass compounds at elevated and subambient temperature under RP-HPLC conditions.

    PubMed

    Zarzycki, P K; Ohta, H; Saito, Y; Jinno, K

    2008-08-01

    The main focus of this study was to explore the capability of native alpha-cyclodextrin, beta-cyclodextrin and gamma-cyclodextrin and their hydroxypropyl derivatives for host-guest interaction with 7,8-dimethoxyflavone, selected steroids (estetrol, estriol, estradiol, estrone, testosterone, cortisone, hydrocortisone, progesterone and 17alpha-hydroxyprogesterone) and polycyclic aromatic hydrocarbons (toluene, naphthalene, 1,8-dimethylnaphthalene, 1-acenaphthenol, acenaphthylene and acenaphthene) under reversed-phase liquid-chromatography conditions. The study revealed that native cyclodextrins interact more efficiently with the analytes investigated than do their hydroxypropyl counterparts. In the low-temperature region, enormously high ratios were observed for polycyclic aromatic hydrocarbons, particularly 1,8-dimethylnaphthalene, acenaphthene and acenaphthylene chromatographed on a beta-cyclodextrin-modified mobile phase. In such a case, the retention times of the polycyclic aromatic hydrocarbons were strongly reduced (e.g. from 127 to 1.2 min for 1,8-dimethylnaphthalene) and were close to the hold-up time of the high-performance liquid chromatography (HPLC) system (0.7 min). Moreover, chiral separation of 1-acenaphthenol optical isomers was observed and the elution order of the enantiomers was determined. Within the steroids group, strong interaction was observed for estradiol and testosterone. The results of cluster analysis indicate that beta-cyclodextrin as well as gamma-cyclodextrin and its hydroxypropyl derivative can be most effective mobile-phase additives under reversed-phase HPLC conditions for 3D-shape-recognition-driven separation, performed at subambient and elevated temperatures, respectively. PMID:18563397

  8. Separation of kafirins on surface porous RP-HPLC columns

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surface porous HPLC columns were investigated for the separation of kafarins, storage proteins of grain sorghum. Kafirins were successfully separated using C3, C8 and C18 surface porous stationary phases in less than 17 min. Separations using a monolithic C18 stationary phase were also developed ...

  9. Optimal Placement of Unified Power Flow Controllers to Improve Dynamic Voltage Stability Using Power System Variable Based Voltage Stability Indices

    PubMed Central

    Albatsh, Fadi M.; Ahmad, Shameem; Mekhilef, Saad; Mokhlis, Hazlie; Hassan, M. A.

    2015-01-01

    This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs) in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs) including the line stability index (LQP), the voltage collapse proximity indicator (VCPI), and the line stability index (Lmn) are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD) software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO) and differential evolution (DE), which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches. PMID:25874560

  10. Optimal placement of unified power flow controllers to improve dynamic voltage stability using power system variable based voltage stability indices.

    PubMed

    Albatsh, Fadi M; Ahmad, Shameem; Mekhilef, Saad; Mokhlis, Hazlie; Hassan, M A

    2015-01-01

    This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs) in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs) including the line stability index (LQP), the voltage collapse proximity indicator (VCPI), and the line stability index (Lmn) are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD) software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO) and differential evolution (DE), which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches. PMID:25874560

  11. The Effect of Ankle Taping and Balance Exercises on Postural Stability Indices in Healthy Women

    PubMed Central

    Akbari, Asghar; Sarmadi, Alireza; Zafardanesh, Parisa

    2014-01-01

    [Purpose] The purpose of this study was to compare the effect of ankle taping and balance exercises on postural stability indices in healthy women. [Subjects and Methods] Thirty healthy female students were randomly assigned into two equal groups: ankle taping and balance exercise. The balance exercise group performed balance exercises for 6 weeks, with 3 sessions per week and each session lasting 40 minutes. Ankle joint taping was performed for 6 weeks and was renewed three times a week. Before and after the interventions, overall, anteroposterior, and mediolateral stability indices were measured with a Biodex Balance System in bilateral and unilateral stance positions with the eyes open and closed. [Results] In the taping group during bilateral standing with the eyes closed, the overall stability index changed from 6±1.4 to 4.8±1.3, anteroposterior stability index changed from 4.2±1.27 to 3.4±0.97, and mediolateral stability index changed from 3.2±0.75 to 2.7± 0.7. In the balance exercise group during bilateral standing with the eyes closed, the overall stability index changed from 5.7±1.69 to 4.5±1.94, anteroposterior stability index changed from 4.1±1.61 to 3±1.21, and mediolateral stability index changed from 3.5±1.4 to 2.2± 1.3. No significant difference was seen between the two groups regarding any study variables. [Conclusion] The results showed that compared with the taping technique, balance training increases postural stability in the majority of the studied balance situations. PMID:24926148

  12. Stability indicating simplified HPLC method for simultaneous analysis of resveratrol and quercetin in nanoparticles and human plasma.

    PubMed

    Kumar, Sandeep; Lather, Viney; Pandita, Deepti

    2016-04-15

    Resveratrol and quercetin are well-known polyphenolic compounds present in common foods, which have demonstrated enormous potential in the treatment of a wide variety of diseases. Owing to their exciting synergistic potential and combination delivery applications, we developed a simple and rapid RP-HPLC method based on isosbestic point detection. The separation was carried out on phenomenex Synergi 4? Hydro-RP 80A column using methanol: acetonitrile (ACN): 0.1% phosphoric acid (60:10:30) as mobile phase. The method was able to quantify nanograms of analytes simultaneously on a single wavelength (269nm), making it highly sensitive, rapid as well as economical. Additionally, forced degradation studies of resveratrol and quercetin were established and the method's applicability was evaluated on PLGA nanoparticles and human plasma. The analytes peaks were found to be well resolved in the presence of degradation products and excipients. The simplicity of the developed method potentializes its suitability for routine in vitro and in vivo analysis of resveratrol and quercetin. PMID:26617040

  13. Certain Actions from the Functional Movement Screen Do Not Provide an Indication of Dynamic Stability

    PubMed Central

    Lockie, Robert G.; Callaghan, Samuel J.; Jordan, Corrin A.; Luczo, Tawni M.; Jeffriess, Matthew D.; Jalilvand, Farzad; Schultz, Adrian B.

    2015-01-01

    Dynamic stability is an essential physical component for team sport athletes. Certain Functional Movement Screen (FMS) exercises (deep squat; left- and right-leg hurdle step; left- and right-leg in-line lunge [ILL]; left- and right-leg active straight-leg raise; and trunk stability push-up [TSPU]) have been suggested as providing an indication of dynamic stability. No research has investigated relationships between these screens and an established test of dynamic stability such as the modified Star Excursion Balance Test (mSEBT), which measures lower-limb reach distance in posteromedial, medial, and anteromedial directions, in team sport athletes. Forty-one male and female team sport athletes completed the screens and the mSEBT. Participants were split into high-, intermediate-, and low-performing groups according to the mean of the excursions when both the left and right legs were used for the mSEBT stance. Any between-group differences in the screens and mSEBT were determined via a one-way analysis of variance with Bonferroni post hoc adjustment (p < 0.05). Data was pooled for a correlation analysis (p < 0.05). There were no between-group differences in any of the screens, and only two positive correlations between the screens and the mSEBT (TSPU and right stance leg posteromedial excursion, r = 0.37; left-leg ILL and left stance leg posteromedial excursion, r = 0.46). The mSEBT clearly indicated participants with different dynamic stability capabilities. In contrast to the mSEBT, the selected FMS exercises investigated in this study have a limited capacity to identify dynamic stability in team sport athletes. PMID:26557187

  14. Respiration and enzymatic activities as indicators of stabilization of sewage sludge composting.

    PubMed

    Nikaeen, Mahnaz; Nafez, Amir Hossein; Bina, Bijan; Nabavi, BiBi Fatemeh; Hassanzadeh, Akbar

    2015-05-01

    The objective of this work was to study the evolution of physico-chemical and microbial parameters in the composting process of sewage sludge (SS) with pruning wastes (PW) in order to compare these parameters with respect to their applicability in the evaluation of organic matter (OM) stabilization. To evaluate the composting process and organic matter stability, different microbial activities were compared during composting of anaerobically digested SS with two volumetric ratios, 1:1 and 3:1 of PW:SS and two aeration techniques including aerated static piles (ASP) and turned windrows (TW). Dehydrogenase activity, fluorescein diacetate hydrolysis, and specific oxygen uptake rate (SOUR) were used as microbial activity indices. These indices were compared with traditional parameters, including temperature, pH, moisture content, organic matter, and C/N ratio. The results showed that the TW method and 3:1 (PW:SS) proportion was superior to the ASP method and 1:1 proportion, since the former accelerate the composting process by catalyzing the OM stabilization. Enzymatic activities and SOUR, which reflect microbial activity, correlated well with temperature fluctuations. Based on these results it appears that SOUR and the enzymatic activities are useful parameters to monitor the stabilization of SS compost. PMID:25728091

  15. Radon as an Indicator of Nocturnal Atmospheric Stability: A Simplified Theoretical Approach

    NASA Astrophysics Data System (ADS)

    Omori, Yasutaka; Nagahama, Hiroyuki

    2015-09-01

    Nocturnal evolution of radon concentration and the height of a box model, which is determined from radon concentration and local radon flux at the ground, are used as indicators of nocturnal atmospheric stability in single-height observations. However, quantitative relationships between these indicators and meteorological conditions, including the turbulent diffusion coefficient, have not yet been well established. Here, we construct a simple model based on the heat exchange process of the lower atmosphere to relate these parameters. The model neglects radiative flux divergence and assumes a uniform constant radon flux, making it most applicable to low wind conditions at sites well-removed from coastal influences, when advective effects are minimal. The model shows that the box height (equivalent mixing height) can be determined from near-surface parameters including sensible heat flux and the decrease in potential temperature after sunset. For these parameters, static stability and mechanical mixing components are incorporated. In addition, the constructed equations suggest the equivalent mixing height is proportional to the inversion layer height with a slope that depends on the vertical profile of potential temperature. The equivalent mixing height can be also related to the turbulent diffusion intensity. We demonstrate that radon observations at a single height are useful for monitoring nocturnal atmospheric stability.

  16. Soil aggregate stability as an indicator for eco-engineering effectiveness?

    NASA Astrophysics Data System (ADS)

    Graf, Frank

    2015-04-01

    Eco-engineering aims at stabilising soil and slopes by applying technical and biological measures. Engineering structures are commonly well defined, immediately usable and operative, and their stability effects quantifiable and verifiable. Differently, the use of plants requires more restrictive boundary conditions and the protection potential is rarely easily calculable and develop-ing as a function of growth rate. Although the use of vegetation is widely appreciated and their stabilising effect recognised, there is an increasing demand on sound facts on its efficiency, in particular, in relation to time. Conclusively, a certain necessity has been recognised to monitor, assess and quantify the effectiveness of ecological restora-tion measures in order to facilitate the transfer of technology and knowledge. Recent theoretical models emphasize the im-portance of taking an integrated monitoring approach that considers multiple variables. However, limited financial and time resources often prevent such comprehensive assessments. A solution to this problem may be to use integrated indicators that reflect multiple aspects and, therefore, allow extensive information on ecosystem status to be gathered in a relatively short time. Among various other indicators, such as fractal dimension of soil particle size distribution or microbiological parameters, soil aggregate stability seems the most appropriate indicator with regard to protecting slopes from superficial soil failure as it is critical to both plant growth and soil structure. Soil aggregation processes play a crucial role in re-establishing soil structure and function and, conclusively, for successful and sustainable re-colonisation. Whereas the key role of soil aggregate stability in ecosystem functioning is well known concerning water, gas, and nutrient fluxes, only limited information is available with regard to soil mechanical and geotechnical aspects. Correspondingly, in the last couple of years several studies have been performed in order to bridge this gap addressing partic-ularly the influence of root growth and mycorrhizal fungi on the resistance of soil aggregates against disintegration and linking it to slope stability. As superficial soil failure is often related to heavy rainstorms and, in this regard, mainly due to water satura-tion, recent investigations focused on the pore water pressure, too. Summarising main results of the different studies a positive relationship between soil aggregate stability and traditional soil mechanical shear strength parameters was found, e.g. given certain soil conditions, an increase in aggregate stability may be equated to an increase of the angle of internal friction ?' and/or cohesion c'. In addition, almost all investigations showed a strong positive correlation between root length per soil volume and soil aggregate stability. In respect of mycorrhizal fungi, results are not yet as clear. On the one hand it was found that the use of unspecific (commercial) inoculum had no or even a negative effect on root growth within the first vegetation period and, correspondingly, on soil aggregate stability. However, the use of specific plant fungi combinations almost ever resulted in an obvious acceleration of root growth immediately with con-comitant gain of soil stability. As far as pore water pressure is concerned we did not yet find an interpretation that is fairly straightforward and not overly prone to controversy. It looks like soil aggregated by mycorrhized plants does have a higher capacity for building up pressure than such permeated by non-mycorrhized roots. Within this scope results of several studies showing these (inter-) relationships and correlations are presented and differences as well as unexpected results discussed.

  17. Labeling, Stability and Biodistribution Studies of 99mTc-cyclized Tyr3-octreotate Derivatives

    PubMed Central

    Bigott-Hennkens, Heather M.; Dannoon, Shorouk F.; Noll, Samantha M.; Ruthengael, Varyanna C.; Jurisson, Silvia S.; Lewis, Michael R.

    2010-01-01

    Introduction To probe the interplay between radiotracer stability and somatostatin receptor affinity, Tyr3-octreotate and six variations of its peptide sequence, for which the Re-cyclized products were previously reported, were radiolabeled with 99mTc and investigated for their in vitro stability. Methods Radiolabeling of the peptides was effected by ligand exchange from 99mTc-glucoheptonate, and the desired products were purified by radio-RP-HPLC. The in vitro stability in phosphate-buffered saline, mouse serum, and cysteine solutions at physiological temperature and pH for all seven 99mTc-cyclized peptides was determined by radio-RP-HPLC and radio-TLC. Normal CF-1 mouse biodistribution studies were performed for three of the 99mTc-cyclized peptides. Results Based on the fully characterized Re-cyclized peptide analogues, four 99mTc-coordination motifs were proposed for the 99mTc-cyclized peptides. Technetium-99m-cyclized Tyr3-octreotate derivatives with N2S2 metal coordination modes and large metal ring sizes were susceptible to oxidation and loss of 99mTc in the form of 99mTcO4?, as evidenced by their instability in the various solutions under physiological conditions (15–58% intact at 24 h). As anticipated, the addition of a third cysteine to the sequence stabilized the 99mTc metal coordination, and peptides with NS3 coordination modes remained >85% intact out to 24 h. No significant differences were observed in the biodistribution studies performed with three peptides of varying stabilities. Conclusions Improvements in stability were not sufficient to outweigh the low somatostatin receptor affinity for the peptides in this study. Further improvements in the peptide sequence and/or metal coordination are needed to result in a radiodiagnostic/radiotherapeutic pair for targeting the somatostatin receptor. PMID:21531292

  18. Evaluation of the stability indices for the thunderstorm forecasting in the region of Belgrade, Serbia

    NASA Astrophysics Data System (ADS)

    Vujovi?, D.; Paskota, M.; Todorovi?, N.; Vu?kovi?, V.

    2015-07-01

    The pre-convective atmosphere over Serbia during the ten-year period (2001-2010) was investigated using the radiosonde data from one meteorological station and the thunderstorm observations from thirteen SYNOP meteorological stations. In order to verify their ability to forecast a thunderstorm, several stability indices were examined. Rank sum scores (RSSs) were used to segregate indices and parameters which can differentiate between a thunderstorm and no-thunderstorm event. The following indices had the best RSS values: Lifted index (LI), K index (KI), Showalter index (SI), Boyden index (BI), Total totals (TT), dew-point temperature and mixing ratio. The threshold value test was used in order to determine the appropriate threshold values for these variables. The threshold with the best skill scores was chosen as the optimal. The thresholds were validated in two ways: through the control data set, and comparing the calculated indices thresholds with the values of indices for a randomly chosen day with an observed thunderstorm. The index with the highest skill for thunderstorm forecasting was LI, and then SI, KI and TT. The BI had the poorest skill scores.

  19. PrimeSupplier Cross-Program Impact Analysis and Supplier Stability Indicator Simulation Model

    NASA Technical Reports Server (NTRS)

    Calluzzi, Michael

    2009-01-01

    PrimeSupplier, a supplier cross-program and element-impact simulation model, with supplier solvency indicator (SSI), has been developed so that the shuttle program can see early indicators of supplier and product line stability, while identifying the various elements and/or programs that have a particular supplier or product designed into the system. The model calculates two categories of benchmarks to determine the SSI, with one category focusing on agency programmatic data and the other focusing on a supplier's financial liquidity. PrimeSupplier was developed to help NASA smoothly transition design, manufacturing, and repair operations from the Shuttle program to the Constellation program, without disruption in the industrial supply base.

  20. A validated stability-indicating UPLC method for desloratadine and its impurities in pharmaceutical dosage forms.

    PubMed

    Rao, Dantu Durga; Satyanarayana, N V; Malleswara Reddy, A; Sait, Shakil S; Chakole, Dinesh; Mukkanti, K

    2010-02-01

    A novel stability-indicating gradient reverse phase ultra-performance liquid chromatographic (RP-UPLC) method was developed for the determination of purity of desloratadine in presence of its impurities and forced degradation products. The method was developed using Waters Aquity BEH C18 column with mobile phase containing a gradient mixture of solvents A and B. The eluted compounds were monitored at 280nm. The run time was 8min within which desloratadine and its five impurities were well separated. Desloratadine was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. Desloratadine was found to degrade significantly in oxidative and thermal stress conditions and stable in acid, base, hydrolytic and photolytic degradation conditions. The degradation products were well resolved from main peak and its impurities, thus proved the stability-indicating power of the method. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. This method was also suitable for the assay determination of desloratadine in pharmaceutical dosage forms. PMID:19815361

  1. Stability-Indicating HPLC Determination of Trandolapril in Bulk Drug and Pharmaceutical Dosage Forms

    PubMed Central

    Al-Hawash, Leena A.; Shakya, Ashok K.; Saleem, Maher L.

    2015-01-01

    A rapid, simple, accurate, precise, economical, robust, and stability indicating reverse phase HPLC-PDA procedure has been developed and validated for the determination of trandolapril. The trandolapril was separated isocratically on Hypersil-Gold C18 column (250?mm × 4.6?mm, 5??m) with a mobile phase consisting of 50% acetonitrile and 50% water (containing 0.025% triethylamine, pH 3.0 ± 0.1), at 25 ± 2°C. Retention time of the drug was ~4.6?min. The eluted compounds were monitored and identified at 210?nm. The linearity of the method was excellent (r2 > 0.9999) over the concentration range of 1–24??g/mL; the limit of detection (LOD) and limit of quantitation (LOQ) were 0.0566??g/mL and 0.1715??g/mL, respectively. The overall precision was less than 2%. Mean recovery of trandolapril was more than 99%; no interference was found from the component present in the preparation. Stability studies indicate that the drug was stable to sunlight and UV light. The drug gives 6 different oxidative products on exposure to hydrogen peroxide. Slight degradation was observed in acidic condition. Degradation was higher in the alkaline condition compared to other conditions. The robustness of the method was studied using factorial design experiment. PMID:25802524

  2. Stability indicating HPLC-UV method for determination of dapoxetine HCl in pharmaceutical product.

    PubMed

    Liew, Kai Bin; Peh, Kok Khiang

    2014-01-01

    A stability-indicating HPLC-UV method for the determination of dapoxetine hydrochloride in solution and pharmaceutical product was developed. The mobile phase was composed of acetonitrile and 0.2 M ammonium acetate buffer at 50 : 50 ratio. The chromatographic parameters, theoretical plates (N), tailing factor (T), capacity factor (k') and peak asymmetry factor (As) were calculated. Stress degradation studies, namely, acid, alkali, oxidation, heat and UV light, were performed. The analyte was eluted at 5.8 min using gradient system at a flow rate of 1.5 mL/min. The theoretical plates count was > 2000, tailing factor < 1.54, capacity factor > 5.38 and peak asymmetry factor was < 1.10. The method was linear from 1 to 40 microg/mL with a correlation coefficient of 0.9994. The intraday precision and accuracy values were 0.14-1.54% and 0.63-1.83%, respectively. On the other hand, the interday precision and accuracy results were 0.49-1.83% and 1.15-1.85%, respectively. The drug solution was stable at ambient room temperature (26 degrees C) for 48 h. Dapoxetine HCI was found susceptible to oxidation and degraded slightly under acid and alkali conditions but was stable under UV light and heat. No interference from tablet excipiets and degradation products was found. Hence, the method can be employed as a stability-indicating method for the determination of dapoxetine HCl in pharmaceutical products. PMID:25265818

  3. Stability-indicating HPLC determination of trandolapril in bulk drug and pharmaceutical dosage forms.

    PubMed

    Al-Hawash, Leena A; Shakya, Ashok K; Saleem, Maher L

    2015-01-01

    A rapid, simple, accurate, precise, economical, robust, and stability indicating reverse phase HPLC-PDA procedure has been developed and validated for the determination of trandolapril. The trandolapril was separated isocratically on Hypersil-Gold C18 column (250?mm × 4.6?mm, 5??m) with a mobile phase consisting of 50% acetonitrile and 50% water (containing 0.025% triethylamine, pH 3.0 ± 0.1), at 25 ± 2°C. Retention time of the drug was ~4.6?min. The eluted compounds were monitored and identified at 210?nm. The linearity of the method was excellent (r (2) > 0.9999) over the concentration range of 1-24??g/mL; the limit of detection (LOD) and limit of quantitation (LOQ) were 0.0566??g/mL and 0.1715??g/mL, respectively. The overall precision was less than 2%. Mean recovery of trandolapril was more than 99%; no interference was found from the component present in the preparation. Stability studies indicate that the drug was stable to sunlight and UV light. The drug gives 6 different oxidative products on exposure to hydrogen peroxide. Slight degradation was observed in acidic condition. Degradation was higher in the alkaline condition compared to other conditions. The robustness of the method was studied using factorial design experiment. PMID:25802524

  4. Tunable release of clavam from clavam stabilized gold nanoparticles--design, characterization and antimicrobial study.

    PubMed

    Manju, V; Dhandapani, P; Gurusamy Neelavannan, M; Maruthamuthu, S; Berchmans, S; Palaniappan, A

    2015-04-01

    A facile one-step approach is developed to synthesize highly stable (up to 6months) gold nanoparticles (GNPs) using Clavam, pharmaceutical form of amoxicillin which contains a mixture of amoxicillin and potassium salt of clavulanic acid, at room temperature (25-30°C). The clavam stabilized GNPs are characterized using various techniques including UV-Visible, FT-IR spectrophotometry and transmission electron microscopy (TEM). Tunable release of clavam from clavam stabilized GNPs is demonstrated using intracellular concentrations of glutathione (GSH). The process is monitored using an UV-Vis spectroscopy and the amount of clavam released in terms of amoxicillin concentration is quantitatively estimated using reverse phase high performance liquid chromatographic (RP-HPLC) technique. In vitro study reveals that the clavam released from GNPs' surface was found to show a significant enhancement in antibacterial activity against Escherichia coli and the cause of enhancement is addressed. PMID:25686977

  5. Stability-Indicating HPLC Assay for Determination of Idebenone in Pharmaceutical Forms

    PubMed Central

    Kombath, Sonoube; Balde, Issa-Bella; Carret, Sandra; Kabiche, Sofiane; Cisternino, Salvatore; Fontan, Jean-Eudes; Schlatter, Joël

    2015-01-01

    A stability-indicating method was validated for the determination in pharmaceutical forms of idebenone a coenzyme Q10-like compound. The assay was achieved by liquid chromatography analysis using a reversed-phase C18 column and a detector set at 480?nm. The optimized mobile phase consisted of isocratic flow rate at 1.0?mL/min for 3?min with methanol. The linearity of the assay was demonstrated in the range of 3.0 to 8.0?mg/mL with a correlation coefficient r2 > 0.998. The limits of detection and quantification were 0.03 and 0.05?mg/mL, respectively. The intraday and interday precisions were less than 1.0%. Accuracy of the method ranged from 98.6 to 101.5% with RSD < 0.6%. Specificity of the assay showed no interference from tablets components and breakdown products formed by alkaline, acidic, oxidative, sunlight, and high temperature conditions. This method allows accurate and reliable determination of idebenone for drug stability assay in pharmaceutical studies. PMID:26605105

  6. Stability Indicating Liquid Chromatographic Method for the Simultaneous Determination of Rosuvastatin and Ezetimibe in Pharmaceutical Formulations

    PubMed Central

    Mukthinuthalapati, Mathrusri Annapurna; Bukkapatnam, Venkatesh; Bandaru, Sai Pavan Kumar

    2014-01-01

    Purpose: A simple stability indicating reverse phase liquid chromatographic method was developed for the simultaneous determination of rosuvastatin and ezetimibe in pharmaceutical formulations. Methods: Best chromatographic response was achieved with C18 column (250 X 4.6 mm, 5µm) with photo diode array (PDA) detector. The mobile phase was composed of a mixture of sodium acetate buffer (pH 4.0) and acetonitrile (30:70, %v/v) with a flow rate of 1.2 mL/min. (UV detection at 254 nm). Rosuvastatin and ezetimibe were subjected to stress conditions of degradation and the method was validated as per ICH guidelines. Results: The method shows linearity over a concentration range of 0.5-250 µg/ml for both rosuvastatin (r2 = 0.9993) and ezetimibe (r2 = 0.9996). Both the drugs are highly sensitive towards alkaline conditions in comparison to other stress conditions. Conclusion: The proposed method can be successfully applied to perform long-term and accelerated stability studies for the simultaneous determination of rosuvastatin and ezetimibe in pharmaceutical formulations. PMID:25436199

  7. Stability-indicating LC method for the estimation of bendamustine hydrochloride and its related impurities.

    PubMed

    Kasa, Srinivasulu; Raja Sekhar Reddy, M; Kadaboina, Raja Sekhar; Murki, Veerender; Mulukutla, Venkata Suryanarayana

    2014-08-01

    A novel, simple, sensitive and stability-indicating high-performance liquid chromatography method was developed and validated for the quantification of impurities (process related and degradants) and the assay determination of Bendamustine hydrochloride. A chromatographic separation of Bendamustine and its impurities was achieved with an Inertsil ODS-2 analytical column, 250 × 4.6 mm, 5 µm, using gradient elution with mobile phase A consisting of a mixture of water and trifluoroacetic acid (1000:1, v/v) and mobile phase B consisting of acetonitrile. The instrumental settings included a flow rate of 1.0 mL/min, column temperature of 27°C and a detector wavelength of 233 nm, using a photodiode array detector. The tailing factor for Bendamustine was 1.10. Bendamustine hydrochloride was exposed to thermal, photolytic, hydrolytic and oxidative stress conditions and the stressed samples were analyzed by the proposed method. Peak homogeneity data of Bendamustine were obtained by using a photodiode array detector in the stressed sample chromatograms, which demonstrated the specificity of the method for estimation in the presence of degradants. The developed method was validated for parameters such as precision, accuracy, linearity, limit of detection, limit of quantification, ruggedness and robustness. The stability tests were also performed on drug substances as per International Conference on Harmonization guidelines. PMID:23825351

  8. Stability-Indicating HPLC Assay for Determination of Idebenone in Pharmaceutical Forms.

    PubMed

    Kombath, Sonoube; Balde, Issa-Bella; Carret, Sandra; Kabiche, Sofiane; Cisternino, Salvatore; Fontan, Jean-Eudes; Schlatter, Joël

    2015-01-01

    A stability-indicating method was validated for the determination in pharmaceutical forms of idebenone a coenzyme Q10-like compound. The assay was achieved by liquid chromatography analysis using a reversed-phase C18 column and a detector set at 480?nm. The optimized mobile phase consisted of isocratic flow rate at 1.0?mL/min for 3?min with methanol. The linearity of the assay was demonstrated in the range of 3.0 to 8.0?mg/mL with a correlation coefficient r (2) > 0.998. The limits of detection and quantification were 0.03 and 0.05?mg/mL, respectively. The intraday and interday precisions were less than 1.0%. Accuracy of the method ranged from 98.6 to 101.5% with RSD < 0.6%. Specificity of the assay showed no interference from tablets components and breakdown products formed by alkaline, acidic, oxidative, sunlight, and high temperature conditions. This method allows accurate and reliable determination of idebenone for drug stability assay in pharmaceutical studies. PMID:26605105

  9. Stability indicating HPLC method for the simultaneous determination of moxifloxacin and prednisolone in pharmaceutical formulations

    PubMed Central

    2012-01-01

    Background A simple, specific, and fast stability indicating reverse phase liquid chromatographic method was established for instantaneous determination of moxifloxacin and prednisolone in bulk drugs and pharmaceutical formulations. Results Optimum chromatographic separations among the moxifloxacin, prednisolone and stress-induced degradation products were achieved within 10 minutes by use of BDS Hypersil C8 column (250 X 4.6 mm, 5 ?m) as stationary phase with mobile phase consisted of a mixture of phosphate buffer (18 mM) containing 0.1% (v/v) triethylamine, at pH 2.8 (adjusted with dilute phosphoric acid) and methanol (38:62 v/v) at a flow rate of 1.5 mL min-1. Detection was performed at 254 nm using diode array detector. The method was validated in accordance with ICH guidelines. Response was a linear function of concentrations over the range of 20–80 ?g mL-1 for moxifloxacin (r2 ? 0.998) and 40–160 ?g mL-1 for prednisolone (r2 ? 0.998). The method was resulted in good separation of both the analytes and degradation products with acceptable tailing and resolution. The peak purity index for both the analytes after all types of stress conditions was ? 0.9999 indicated a complete separation of both the analyte peaks from degradation products. The method can therefore, be regarded as stabilityindicating. Conclusions The developed method can be applied successfully for simultaneous determination of moxifloxacin and prednisolone in pharmaceutical formulations and their stability studies. PMID:22947049

  10. Bioremediation of Contaminated Lake Sediments and Evaluation of Maturity Indicies as Indicators of Compost Stability

    PubMed Central

    Rekha, P.; Suman Raj, D. S.; Aparna, C.; Bindu, V. Hima; Anjaneyulu, Y.

    2005-01-01

    Land contamination is one of the widely addressed problems, which is gaining importance in many developed and developing countries. International efforts are actively envisaged to remediate contaminated sites as a response to adverse health effects. Popular conventional methodologies only transfer the phase of the contaminant involving cost intensive liabilities besides handling risk of the hazardous waste. Physico-chemical methods are effective for specific wastes, but are technically complex and lack public acceptance for land remediation. “Bioremediation”, is one of the emerging low-cost technologies that offer the possibility to destroy various contaminants using natural biological activities. Resultant non -toxic end products due to the microbial activity and insitu applicability of this technology is gaining huge public acceptance. In the present study, composting is demonstrated as a bioremediation methodology for the stabilization of contaminated lake sediments of Hyderabad, A.P, India. Lake sediment contaminated with organics is collected from two stratums – upper (0.25 m) and lower (0.5m) to set up as Pile I (Upper) and Pile II (Lower) in the laboratory. Lime as a pretreatment to the lake sediments is carried out to ensure metal precipitation. The pretreated sediment is then mixed with organic and inorganic fertilizers like cow dung, poultry manure, urea and super phosphate as initial seeding amendments. Bulking agents like sawdust and other micronutrients are provided. Continuous monitoring of process control parameters like pH, moisture content, electrical conductivity, total volatile solids and various forms of nitrogen were carried out during the entire course of the study. The stability of the compost was evaluated by assessing maturity indices like C/N, Cw (water soluble carbon), CNw (Cw/Nw), nitrification index (NH4/NO?3), Cation Exchange Capacity (CEC), germination index, humification ratio, compost mineralization index (ash content/oxidizable carbon), sorption capacity index (CEC/oxidizable carbon). Enzyme activities of agricultural interest like urease, phosphatase, ?-glucosidase, dehydrogenase and BAA-hydrolyzing protease, which are involved in the nitrogen, phosphorus and carbon cycles, were also assessed. Total content of macro and micronutrients in the final compost was also determined to assess the fertilizer value. The studies revealed that composting could be applied as a remediation technology after removing the top sediment. The maturity indices that are evaluated from the present study can be used to validate the success of the remediation technology. PMID:16705825

  11. Application of stability-indicating HPTLC method for quantitative determination of metadoxine in pharmaceutical dosage form.

    PubMed

    Kaul, Neeraj; Agrawal, Himani; Patil, Bharat; Kakad, Abhijit; Dhaneshwar, S R

    2005-04-01

    A sensitive, selective, precise and stability-indicating high-performance thin-layer chromatographic method for analysis of metadoxine both as a bulk drug and in formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of acetone-chloroform-methanol-ammonia (7.0:4.0:3.0:1.2, v/v/v/v). Densitometric analysis of metadoxine was carried out in the absorbance mode at 315 nm. This system was found to give compact spots for metadoxine (Rf value of 0.45+/-0.02, for six replicates). Metadoxine was subjected to acid, alkali and neutral hydrolysis, oxidation, dry and wet heat treatment and photo and UV degradation. The drug undergoes degradation under all stress conditions. Also, the degraded products were well resolved from the pure drug with significantly different Rf values. The method was validated for linearity, precision, robustness, LOD, LOQ, specificity and accuracy. Linearity was found to be in the range of 100-1500 ng/spot with significantly high value of correlation coefficient r2=0.9997+/-1.02. The linear regression analysis data for the calibration plots showed good linear relationship with r2=0.9999+/-0.58 in the working concentration range of 200-700 ng/spot. The mean value of slope and intercept were 0.11+/-0.04 and 18.73+/-1.89, respectively. The limits of detection and quantitation were 50 and 100 ng/spot, respectively. Statistical analysis proves that the method is repeatable and specific for the estimation of the said drug. As the method could effectively separate the drug from its degradation products, it can be employed as a stability-indicating one. Moreover, the proposed HPTLC method was utilized to investigate the kinetics of acid and base degradation process. Arrhenius plot was constructed and activation energy was calculated respectively for acid and base degradation process. PMID:15848212

  12. In vitro characterization of a novel C,N-cyclometalated benzimidazole Ru(II) arene complex: stability, intracellular distribution and binding, effects on organic osmolyte homeostasis and induction of apoptosis.

    PubMed

    Støving Dam, Celina; Alejo Perez Henarejos, Sergio; Tsolakou, Theodosia; Alexander Segato, Christian; Gammelgaard, Bente; Yellol, Gorakh S; Ruiz, José; Lambert, Ian Henry; Stürup, Stefan

    2015-05-01

    In the present work a novel C,N-cyclometalated benzimidazole Ru(ii) arene complex (GY34) was characterized by applying an alternative, diverse approach considering both chemical and biological aspects. RP-HPLC-ICP-MS and RP-HPLC-ESI-MS analysis proved that GY34 in both RPMI-1640 cell medium and ammonium acetate buffer was transformed into several subspecies and the importance of evaluating and controlling analyte stability throughout experiments was demonstrated. Applying a novel cell fractionation protocol GY34 was found to target cell nuclei and mitochondria in Ehrlich Lettré Ascites (ELA) cells, with the intracellular distribution depending on GY34 concentration in the cell medium during incubation. In ELA cells 96 ± 0.2% of cytosolic GY34 was bound to high-molecular species. Furthermore, using the tracer technique GY34 was found to reduce uptake and increase release of the organic osmolyte taurine in ELA cells, with innate resistance to Cisplatin and in A2780 human ovarian cancer cells, with acquired resistance to Cisplatin. Importantly, FACS analysis revealed that GY34 induced apoptosis in ELA cells. The present data suggest the potential of GY34 in overcoming Cisplatin resistance. The methodology applied can be used as a general protocol and an additional tool in the initial evaluation of novel metal-based drugs. PMID:25805368

  13. A Stability Indicating HPLC Method for the Determination of Fluvoxamine in Pharmaceutical Dosage Forms

    PubMed Central

    Souri, Effat; Donyayi, Hassan; khaniha, Reza Ahmad; Barazandeh Tehrani, Maliheh

    2015-01-01

    Fluvoxamine maleate is a selective serotonin reuptake inhibitor, which is used for the treatment of different types of depressive disorders. In the present study, a stability indicating HPLC method was developed and validated for the determination of fluvoxamine maleate. The chromatographic separation was carried out using a Nova-Pak CN column and a mixture of K2HPO4 50 mM (pH 7.0) and acetonitrile (60: 40, v/v) as the mobile phase. Target compounds were detected using a UV detector set at 235 nm. The developed method was linear over the concentration range of 1-80 ?g/ml with acceptable precision (CV values < 2.0%) and accuracy (error values < 1.6%). The degradation studies showed that fluvoxamine maleate is relatively unstable under acidic, basic and oxidative conditions and also when exposed to UV radiation. On the other hand, the bulk powder of fluvoxamine maleate was relatively stable when exposed to visible light or heat. The proposed method was successfully applied for the determination of active ingredient of fluvoxamine dosage form without any interference from tablet excipients.

  14. Stability-indicating HPLC Method for Simultaneous Determination of Montelukast and Fexofenadine Hydrochloride

    PubMed Central

    Pankhaniya, Mona; Patel, Parula; Shah, J. S.

    2013-01-01

    A simple, specific, accurate, and stability-indicating reversed-phase high-performance liquid chromatographic method was developed for the simultaneous determination of montelukast and fexofenadine hydrochloride, using a Lichrospher® 100, RP-18e column and a mobile phase composed of methanol:0.1% o-phosphoric acid (90:10 v/v), pH 6.8. The retention times of montelukast and fexofenadine hydrochloride were found to be 10.16 and 12.03 min, respectively. Linearity was established for montelukast and fexofenadine hydrochloride in the range of 2-10 ?g/ml and 24-120 ?g/ml, respectively. The percentage recoveries of montelukast and fexofenadine hydrochloride were found to be in the range of 99.09 and 99.81%, respectively. Both the drugs were subjected to acid and base hydrolysis, oxidation, photolytic, and thermal degradation conditions. The degradation products of montelukast and fexofenadine hydrochloride were well resolved from the pure drug with significant differences in their retention time values. This method can be successfully employed for simultaneous quantitative analysis of montelukast and fexofenadine hydrochloride in bulk drugs and formulations. PMID:24082344

  15. Spatial scale of similarity as an indicator of metacommunity stability in exploited marine systems.

    PubMed

    Shackell, Nancy L; Fisher, Jonathan A D; Frank, Kenneth T; Lawton, Peter

    2012-01-01

    The spatial scale of similarity among fish communities is characteristically large in temperate marine systems: connectivity is enhanced by high rates of dispersal during the larval/juvenile stages and the increased mobility of large-bodied fish. A larger spatial scale of similarity (low beta diversity) is advantageous in heavily exploited systems because locally depleted populations are more likely to be "rescued" by neighboring areas. We explored whether the spatial scale of similarity changed from 1970 to 2006 due to overfishing of dominant, large-bodied groundfish across a 300 000-km2 region of the Northwest Atlantic. Annually, similarities among communities decayed slowly with increasing geographic distance in this open system, but through time the decorrelation distance declined by 33%, concomitant with widespread reductions in biomass, body size, and community evenness. The decline in connectivity stemmed from an erosion of community similarity among local subregions separated by distances as small as 100 km. Larger fish, of the same species, contribute proportionally more viable offspring, so observed body size reductions will have affected maternal output. The cumulative effect of nonlinear maternal influences on egg/larval quality may have compromised the spatial scale of effective larval dispersal, which may account for the delayed recovery of certain member species. Our study adds strong support for using the spatial scale of similarity as an indicator of metacommunity stability both to understand the spatial impacts of exploitation and to refine how spatial structure is used in management plans. PMID:22471094

  16. Stress Degradation Studies on Varenicline Tartrate and Development of a Validated Stability-Indicating HPLC Method

    PubMed Central

    Pujeri, Sudhakar S.; Khader, Addagadde M. A.; Seetharamappa, Jaldappagari

    2012-01-01

    A simple, rapid and stability-indicating reversed-phase liquid chromatographic method was developed for the assay of varenicline tartrate (VRT) in the presence of its degradation products generated from forced decomposition studies. The HPLC separation was achieved on a C18 Inertsil column (250 mm × 4.6 mm i.d. particle size is 5 ?m) employing a mobile phase consisting of ammonium acetate buffer containing trifluoroacetic acid (0.02M; pH 4) and acetonitrile in gradient program mode with a flow rate of 1.0 mL min?1. The UV detector was operated at 237 nm while column temperature was maintained at 40 °C. The developed method was validated as per ICH guidelines with respect to specificity, linearity, precision, accuracy, robustness and limit of quantification. The method was found to be simple, specific, precise and accurate. Selectivity of the proposed method was validated by subjecting the stock solution of VRT to acidic, basic, photolysis, oxidative and thermal degradation. The calibration curve was found to be linear in the concentration range of 0.1–192 ?g mL?1 (R2 = 0.9994). The peaks of degradation products did not interfere with that of pure VRT. The utility of the developed method was examined by analyzing the tablets containing VRT. The results of analysis were subjected to statistical analysis. PMID:22396908

  17. Synthesis of tritium labelled endomorphin II and its stability in the radioreceptor assay

    NASA Astrophysics Data System (ADS)

    Tömböly, Cs.; Spetea, M.; Borsodi, A.; Tóth, G.

    1999-01-01

    Endomorphine I (Tyr-Pro-Trp-Phe-NH2) and endomorphin II (Tyr-Pro-Phe-Phe-NH2) are recently isolated neuropeptides. They have the highest specificity and affinity for the ?-opiate receptor among all the endogenous substances so far described, and they may be natural ligands for this receptor [1]. We prepared the [3H] endomorphin II with high specific radioactivity (53.4 Ci/mmol) by catalytic dehalotritiation. The precursor [(3,5-I2)Tyr1]-endomorphin II was synthesized by solid phase peptide synthesis using Boc chemistry. Labelled endomorphin II was used to investigate its binding properties in rat brain membrane. The stability of [3H]endomorphin II toward enzymatic degradation in membrane preparation was examined by RP-HPLC and by using a radioactivity detector.

  18. Stability-indicating HPLC Method for Simultaneous Determination of Terbutaline Sulphate, Bromhexine Hydrochloride and Guaifenesin

    PubMed Central

    Porel, A.; Haty, Sanjukta; Kundu, A.

    2011-01-01

    The aim of the present study was the development and subsequent validation of a simple, precise and stability-indicating reversed phase HPLC method for the simultaneous determination of guaifenesin, terbutaline sulphate and bromhexine hydrochloride in the presence of their potential impurities in a single run. The photolytic as well as hydrolytic impurities were detected as 3,5-dihydroxybenzoic acid, 3,5-dihydroxybenzaldehyde, 1-(3,5-dihydroxyphenyl)-2-[(1,1-dimethylethyl) amino]-ethanone from terbutaline, 2-methoxyphenol and an unknown impurity identified as (2RS)-3-(2-hydroxyphenoxy)-propane-1,2-diol from guaifenesin. The chromatographic separation of all the three active components and their impurities was achieved on Wakosil II column, using phosphate buffer (pH 3.0) and acetonitrile as mobile phase which was delivered initially in the ratio of 80:20 (v/v) for 18 min, then changed to 60:40 (v/v) for next 12 min, and finally equilibrated back to 80:20 (v/v) for 10 min. Other HPLC parameters were: Flow rate at 1.0 ml/min, detection wavelengths 248 and 280 nm, injection volume 10 ?l. The calibration graphs plotted with five concentrations of each component were linear with a regression coefficient R2 >0.9999. The limit of detection and limit of quantitation were estimated for all the five impurities. The established method was then validated for linearity, precision, accuracy, and specificity and demonstrated to be applicable to the determination of the active ingredients in commercial and model cough syrup. No interference from the formulation excipients was observed. These results suggest that this LC method can be used for the determination of multiple active ingredients and their impurities in a cough and cold syrup. PMID:22131621

  19. Stability-indicating HPLC Method for Simultaneous Determination of Terbutaline Sulphate, Bromhexine Hydrochloride and Guaifenesin.

    PubMed

    Porel, A; Haty, Sanjukta; Kundu, A

    2011-01-01

    The aim of the present study was the development and subsequent validation of a simple, precise and stability-indicating reversed phase HPLC method for the simultaneous determination of guaifenesin, terbutaline sulphate and bromhexine hydrochloride in the presence of their potential impurities in a single run. The photolytic as well as hydrolytic impurities were detected as 3,5-dihydroxybenzoic acid, 3,5-dihydroxybenzaldehyde, 1-(3,5-dihydroxyphenyl)-2-[(1,1-dimethylethyl) amino]-ethanone from terbutaline, 2-methoxyphenol and an unknown impurity identified as (2RS)-3-(2-hydroxyphenoxy)-propane-1,2-diol from guaifenesin. The chromatographic separation of all the three active components and their impurities was achieved on Wakosil II column, using phosphate buffer (pH 3.0) and acetonitrile as mobile phase which was delivered initially in the ratio of 80:20 (v/v) for 18 min, then changed to 60:40 (v/v) for next 12 min, and finally equilibrated back to 80:20 (v/v) for 10 min. Other HPLC parameters were: Flow rate at 1.0 ml/min, detection wavelengths 248 and 280 nm, injection volume 10 ?l. The calibration graphs plotted with five concentrations of each component were linear with a regression coefficient R(2) >0.9999. The limit of detection and limit of quantitation were estimated for all the five impurities. The established method was then validated for linearity, precision, accuracy, and specificity and demonstrated to be applicable to the determination of the active ingredients in commercial and model cough syrup. No interference from the formulation excipients was observed. These results suggest that this LC method can be used for the determination of multiple active ingredients and their impurities in a cough and cold syrup. PMID:22131621

  20. Synthesis, characterization and stability of a luteinizing hormone-releasing hormone (LHRH)-functionalized poly(amidoamine) dendrimer conjugate.

    PubMed

    Bi, Xiangdong; Shi, Xiangyang; Baker, James R

    2008-01-01

    Cancer targeting is crucial for cancer detection, therapy and targeted drug delivery. A dendrimer-peptide conjugate has been synthesized based on poly(amidoamine) dendrimer generation 5 (PAMAM G5) as a platform and a luteinizing hormone-releasing hormone (LHRH) peptide as a targeting moiety. The synthesized conjugate was fully characterized using nuclear magnetic resonance (NMR), UV-Vis spectrometry, reverse-phase high-performance liquid chromatography (RP-HPLC) and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Further stability experiments showed that the synthesized conjugate was stable after 72-h incubation in phosphate-buffered saline (PBS) buffer (pH 7.4) at 37 degrees C. The synthesized conjugate may find applications in biomedical targeting, gene delivery and imaging. PMID:18177559

  1. Identification and quantification of furanocoumarins in stem bark and wood of eight Algerian varieties of Ficus carica by RP-HPLC-DAD and RP-HPLC-DAD-MS.

    PubMed

    Rouaiguia-Bouakkaz, Samia; Amira-Guebailia, Habiba; Rivière, Céline; Delaunay, Jean-Claude; Waffo-Téguo, Pierre; Mérillon, Jean-Michel

    2013-04-01

    Furanocoumarins are the major phytoalexins of Ficus carica and are effective natural drug candidates for treatment of several types of cancer and skin disease. The objectives of this study were to analyze and quantify linear furanocoumarins, mainly psoralen and bergapten, in wood and bark of stems from eight Algerian varieties of fig and to establish the differences in the content of these metabolites in the eight local samples. Psoralen and bergapten contents in the stem bark and wood (in microg/g DW) varied respectively from 146.6 to 1110.3 and from 395.7 to 1671.8 for psoralen, and from 114.3 to 524.0 and from 144.2 to 718.6 for bergapten. This study fills a gap in our knowledge of furanocoumarin distribution in different parts of the fig tree. Psoralen and bergapten concentrations were higher in the wood than in the stem bark. Most of the dark fruited fig trees produce these two coumarins more than the green ones. PMID:23738460

  2. Stability and maturity of biowaste composts derived by small municipalities: Correlation among physical, chemical and biological indices.

    PubMed

    Oviedo-Ocaña, E R; Torres-Lozada, P; Marmolejo-Rebellon, L F; Hoyos, L V; Gonzales, S; Barrena, R; Komilis, D; Sanchez, A

    2015-10-01

    Stability and maturity are important criteria to guarantee the quality of a compost that is applied to agriculture or used as amendment in degraded soils. Although different techniques exist to evaluate stability and maturity, the application of laboratory tests in municipalities in developing countries can be limited due to cost and application complexities. In the composting facilities of such places, some classical low cost on-site tests to monitor the composting process are usually implemented; however, such tests do not necessarily clearly identify conditions of stability and maturity. In this article, we have applied and compared results of stability and maturity tests that can be easily employed on site (i.e. temperature, pH, moisture, electrical conductivity [EC], odor and color), and of tests that require more complex laboratory techniques (volatile solids, C/N ratio, self-heating, respirometric index, germination index [GI]). The evaluation of the above was performed in the field scale using 2 piles of biowaste applied compost. The monitoring period was from day 70 to day 190 of the process. Results showed that the low-cost tests traditionally employed to monitor the composting process on-site, such as temperature, color and moisture, do not provide consistent determinations with the more complex laboratory tests used to assess stability (e.g. respiration index, self-heating, volatile solids). In the case of maturity tests (GI, pH, EC), both the on-site tests (pH, EC) and the laboratory test (GI) provided consistent results. Although, stability was indicated for most of the samples, the maturity tests indicated that products were consistently immature. Thus, a stable product is not necessarily mature. Conclusively, the decision on the quality of the compost in the installations located in developing countries requires the simultaneous use of a combination of tests that are performed both in the laboratory and on-site. PMID:26216503

  3. Ab-initio simulations of chemical stability indicators of the bis-DGA-type molecule and its radiation degradation products

    SciTech Connect

    Koubsky, T.; Kalvoda, L.; Drab, M.

    2013-07-01

    For hydrometallurgical treatment of the high level liquid waste (HLLW) in the DIAMEX and SANEX processes, organic compounds of the bis-DGA family are used as cation extractants in apolar solvents. For the compound of m-xylylene-bis-diglycolamide high distribution coefficients for Eu and Am were found. Since the environment of the process is highly radioactive and acidic (nitric acid), it is necessary to ensure the stability of the extractants. In order to analyse the process theoretically, the molecule of m-xylylene-bis- diglycolamide and two of its degradation products were simulated by the DFT computational methods (PBE, RPBE, BLYP, B3LYP) available within the simulation environment DMol{sup 3} 6.1 and Gaussian 09 software. The local chemical stability of some locations of the molecule was assessed from the calculated stability indicators (electrostatic potential, Fukui function, HOMO localization). In connection with the chemical treatment, especially the stability against an electrophilic attack was tested. The results of calculated bond orders and spatial distribution of electrostatic potential and HOMO were are successfully correlated with the local and general stability determined by the experiment. These results should be helpful for the further development of the separation process. (authors)

  4. CD and UV Resonance Raman Indicate Little arg-glu Side Chain ?-helix Peptide Stabilization

    PubMed Central

    Hong, Zhenmin; Ahmed, Zeeshan

    2011-01-01

    Electrostatic interactions between side chains can control the conformation and folding of peptides and proteins. We used CD and UV resonance Raman spectroscopy (UVRR) to examine the impact of side chain charge on the conformations of two 21 residue mainly polyala peptides with a few arg and glu residues. We expected that attractions between arg-10 and glu-14 side chains would stabilize the ?-helix conformation compared to a peptide with an arg-14. Surprisingly, CD suggests that the peptide with the glu-14 is less helical. In contrast, the UVRR show that these two peptides have similar ?-helix content. We conclude that the peptide with glu-14 has the same net ?-helix content as the peptide with the arg, but has two ?-helices of shorter length. Thus, side chain interactions between arg-10 and glu-14 have a minor impact on ?-helix stability. The thermal melting of these two peptides is similar. However the glu-14 peptide pH induced melting forms type III turn structures that forms ?-helix-turn-?-helix conformations. PMID:21425805

  5. Comparative stability and growth requirements of S. aureus and faecal indicator bacteria in seawater.

    PubMed

    Fujioka, R S; Unutoa, T M

    2006-01-01

    The fate (stability, multiplication) of S. aureus, E. coli and E. faecalis was determined in three classes of recreational waters (seawater, estuarine, stream) supplemented with nutrients in the form of sewage and peptone. In the absence of sunlight (24 +/- 2 degrees C), all bacteria in all water samples did not multiply and were slowly (days) inactivated. When 50% sewage was added to all water samples, E. coli and E. faecalis multiplied but S. aureus did not. When peptone (0.05%, 0.5%) was the added nutrient, the three bacteria multiplied. In the presence of sunlight (15-27 degrees C), S. aureus was inactivated rapidly (hours) in all water samples. These results show that when their nutritional requirements are met, S. aureus, E. coli and E. faecalis can multiply in the high salinity conditions of seawater. However, under environmental conditions, sunlight is an effective natural bactericidal agent. PMID:17037149

  6. Development, Optimization, and Validation of a Green and Stability-Indicating HPLC Method for Determination of Daptomycin in Lyophilized Powder.

    PubMed

    Tótoli, Eliane Gandolpho; Salgado, Hérida Regina Nunes

    2015-01-01

    Daptomycin is an antimicrobial that plays an important role in clinical practice today because it is considered a promising drug to combat resistant strains, such as methicilin and vancomycin-resistant Gram-positive bacteria. Considering the analysis of daptomycin in a pharmaceutical dosage form, the only method found in literature uses potentially toxic organic solvents. Therefore, the objective of this work was to develop a green and stability-indicating HPLC method for determination of daptomycin in lyophilized powder. The mobile phase was ethanol-water (55+45, v/v) at pH 4.5 pumped at a flow rate of 0.6 mL/min. A C18 column was used, and UV detection was performed at 221 nm. Stress degradation studies were conducted in order to demonstrate the specificity and stability-indicating capability of the method. The method was validated according to International Conference on Harmonization guidelines, proving to be linear (r=0.9996), precise, accurate, robust (demonstrated by the Plackett-Burman model), and specific within the range 20-70 ?g/mL. The retention time of daptomycin was 5.8 min. It can be concluded that the validated method can be a fast, safe, and environmentally friendly alternative for the analysis of daptomycin. PMID:26525246

  7. Stability indicating HPLC-UV method for detection of curcumin in Curcuma longa extract and emulsion formulation.

    PubMed

    Syed, Haroon Khalid; Liew, Kai Bin; Loh, Gabriel Onn Kit; Peh, Kok Khiang

    2015-03-01

    A stability-indicating HPLC-UV method for the determination of curcumin in Curcuma longa extract and emulsion was developed. The system suitability parameters, theoretical plates (N), tailing factor (T), capacity factor (K'), height equivalent of a theoretical plate (H) and resolution (Rs) were calculated. Stress degradation studies (acid, base, oxidation, heat and UV light) of curcumin were performed in emulsion. It was found that N>6500, T<1.1, K' was 2.68-3.75, HETP about 37 and Rs was 1.8. The method was linear from 2 to 200 ?g/mL with a correlation coefficient of 0.9998. The intra-day precision and accuracy for curcumin were ?0.87% and ?2.0%, while the inter-day precision and accuracy values were ?2.1% and ?-1.92. Curcumin degraded in emulsion under acid, alkali and UV light. In conclusion, the stability-indicating method could be employed to determine curcumin in bulk and emulsions. PMID:25306352

  8. Critical Interactions in the Stability Control Region of Tropomyosin

    PubMed Central

    Kirwan, J. Paul; Hodges, Robert S.

    2010-01-01

    Our laboratory has recently described a stability control region in the two-stranded ?-helical coiled-coil ?-tropomyosin that accounts for overall protein stability but is not required for folding. We have used a synthetic peptide approach to investigate three stability control sites within the stability control region (residues 97-118). Two of the sites, electrostatic cluster 1 (97-104, EELDRAQE) and electrostatic cluster 2 (112-118, KLEEAEK), feature sequences with unusually high charge density and the potential to form multiple intrachain and interchain salt bridges (ionic attractions). A third site (105-111, RLATALQ) features an e position Leu residue, an arrangement known previously to enhance coiled-coil stability modestly. A native peptide and 7 peptide analogs of the tropomyosin sequence 85-119 were prepared by Fmoc solid-phase peptide synthesis. Thermal stability measurements by circular dichroism (CD) spectroscopy revealed the following Tm values for the native peptide and three key analogs: 52.9°C (Native), 46.0°C (R101A), 45.3°C (K112A/K118A), and 27.9°C (L110A). The corresponding ?Tm values for the anlaogs, relative to the native peptide, are -6.9°C, -7.6°C, and -25.0°C, respectively. The dramatic contribution to stability made by L110e is three times greater than the contribution of either electrostatic cluster 1 or 2, likely resulting from a novel hydrophobic interaction not previously observed. These thermal stability results were corroborated by temperature profiling analyses using reversed-phase high-performance liquid chromatography (RP-HPLC). We believe that the combined contributions of the interactions within the three stability control sites are responsible for the effect of the stability control region in tropomyosin, with the Leu110e contribution being most critical. PMID:20144718

  9. A validated stability-indicating HPLC method for the simultaneous determination of pheniramine maleate and naphazoline hydrochloride in pharmaceutical formulations

    PubMed Central

    2014-01-01

    Background A simple, rapid, and accurate stability-indicating reverse phase liquid chromatographic method was developed and validated for the simultaneous determination of pheniramine maleate and naphazoline hydrochloride in bulk drugs and pharmaceutical formulations. Results Optimum chromatographic separations among pheniramine maleate, naphazoline hydrochloride and stress-induced degradation products have been achieved within 10 minutes by using an Agilent zorbax eclipse XDB C18 column (150 mm?×?4.6 mm, 5 ?m) as the stationary phase with a mobile phase consisted of 10 mM phosphate buffer pH 2.8 containing 0.5% triethlamine and methanol (68:32, v/v) at a flow rate of 1 mL min-1. Detection was performed at 280 nm using a diode array detector. Theoretical plates for pheniramine maleate and naphazoline hydrochloride were calculated to be 6762 and 6475, respectively. The method was validated in accordance with ICH guidelines with respect to linearity, accuracy, precision, robustness, specificity, limit of detection and quantitation. Regression analysis showed good correlations (R2?>?0.999) for pheniramine maleate in the concentration range of 150–1200 ?g mL-1 and naphazoline hydrochloride in 12.5-100 ?g mL-1. The method results in excellent separation of both the analytes and degradation products. The peak purity factor is ?980 for both analytes after all types of stress, indicating complete separation of both analyte peaks from the stress induced degradation products. Conclusions Overall, the proposed stability-indicating method was suitable for routine quality control and drug analysis of pheniramine maleate and naphazoline hydrochloride in pharmaceutical formulations. PMID:24485011

  10. The unique stability of the photon indices in "dipping" Z-source GX 340+0 throughout spectral states

    NASA Astrophysics Data System (ADS)

    Seifina, Elena; Titarchuk, Lev; Frontera, Filippo

    We present an analysis of the spectral and timing properties of X-ray radiation from accreting neutron star source GX340+0 during its evolution when the electron temperature of the transition layer (TL) kTe monotonically decreases from 21 to 3 keV. We analyze episodes observed with BeppoSAX and RXTE. We reveal that the X-ray broadband energy spectra during all spectral states can be reproduced by a physical model composed of a soft Blackbody component and two Comptonized components (both due to the presence of the TL that upscatters both seed photons of T_s1?1 keV coming from the disk (first component Comptb1), and seed photons of temperature T_{s2}?1.5 keV coming from the neutron star (second component Comptb2) and the iron-line (Gaussian) component. Spectral analysis using this model indicates that the photon power-law indices Gamma_com1 and Gamma_{com2} of the Comptonized components are almost constant, Gamma_{com1} and Gamma_{com2} 2 when kTe changes from 3 to 21 keV along the Z-track. We interpret the detected quasi-stability of the indices of Comptonized components to be near a value of 2. Furthermore, this index stability now found for the Comptonized spectral components of Z-source GX340+0 is similar to that previously established in the atoll sources 4U1728-34, 4U1820-30 and GX3+1, and earlier proposed for a number of X-ray neutron stars (NSs). This behavior of NSs both for atoll and Z-sources is essentially different from that observed in black hole binaries where Gamma_{com} increases during a spectral evolution from the low state to the high state and ultimately saturates at a high mass accretion rate

  11. Regularities of Anthocyanins Retention in RP HPLC for “Water–Acetonitrile–Phosphoric Acid” Mobile Phases

    PubMed Central

    Deineka, V. I.; Deineka, L. A.; Saenko, I. I.

    2015-01-01

    The influence of exchange of HCOOH (System 2) by phosphoric acid (System 1) for acidification of the “acetonitrile–water” mobile phases for reversed-phase HPLC of anthocyanins was investigated in the framework of relative retention analysis. The differences and similarities of anthocyanins separation were revealed. It has been shown that some common features of the quantitative relationships may be used for preliminary anthocyanins structure differentiation, according to the number of OH-groups in anthocyanidin backbone as well as to a number of saccharide molecules in glycoside radicals in position 3 of the anthocyanin without MS detection. PMID:25692073

  12. RP-HPLC Estimation of Imipramine Hydrochloride and Diazepam in Tablets

    PubMed Central

    Srikantha, D.; Raju, R. R.

    2015-01-01

    A simple and rapid reversed phase-high performance liquid chromatographic method was developed for simultaneous determination of imipramine hydrochloride and diazepam in pharmaceutical formulations. The elution was done in isocratic mode utilizing a mobile phase consisting of methanol:water:0.1M sodium acetate (30:50:20 v/v/v) on Chromosil C18 column with a flow rate of 1.0 ml/min and with detection at 243 nm. The measured retention time was 3.33±0.02 min for imipramine hydrochloride and 4.64±0.02 min for diazepam. Linearity was measured in the range 25-150 ?g/ml for imipramine hydrochloride (r2=0.999) and in the range 5-30 ?g/ml for diazepam (r2=0.9994), respectively. The limits of detection and quantitation were 0.03 and 0.1 ?g/ml for imipramine hydrochloride and 0.02 and 0.07 ?g/ml for diazepam. Satisfactory validation was also obtained from recovery (100.95-101.52% for imipramine hydrochloride and 99.47-100.33% for diazepam) studies, intraday and interday precision (<2%) and robustness results. The reported method was the first study of these drugs in combination and could be employed for routine quantitative determination of imipramine hydrochloride and diazepam in tablets. PMID:26180281

  13. RP-HPLC and UV Spectrophotometric Methods for Estimation of Pirfenidone in Pharmaceutical Formulations

    PubMed Central

    Parmar, V. K.; Desai, S. B.; Vaja, T.

    2014-01-01

    High-performance liquid chromatographic and UV spectrophotometric methods were developed and validated for the quantitative determination of pirfenidone, a novel antifibrotic agent used in idiopathic pulmonary fibrosis. Chromatography was carried out by isocratic technique on a reversed-phase C18 Zorbax Eclipse plus column with mobile phase consisting of acetonitrile:water (35:65 %v/v) at flow rate of 0.7 ml/min. The UV spectrophotometric determinations were performed at 317 nm using methanol as a solvent. The proposed methods were validated according to International Conference on Harmonization ICH Q2 (R1) guidelines. The linearity range for pirfenidone was 0.2-5.0 and 3-25 ?g/ml for HPLC and UV method, respectively. Both the methods were accurate and precise with recoveries in the range of 98 and 102 % and relative standard deviation <2 %. The developed methods were successfully applied for determination of pirfenidone in tablets. PMID:25035534

  14. Stability and pharmacokinetic studies of O-palmitoyl amylopectin anchored dipyridamole liposomes.

    PubMed

    Cheng, Ji; Zhu, Jia-bi; Wen, Na; Xiong, Fei

    2006-04-26

    Modified polysaccharides have been used widely to increase physico-chemical stability of liposomes. However, the stability and pharmacokinetic studies on the polysaccharides modified anchored liposomes containing hydrophobic drugs which exist in lipid bilayer membranes were insufficient as compared with the liposomes carrying hydrophilic or ionic drugs in inner aqueous phase. In the present study, a hydrophobic drug, dipyridamole (DIP), was entrapped into liposomes through film hydration. Amylopectin was palmitoylated and anchored on the surface of plain DIP liposomes. Subsequently, the stabilities of DIP ethanol solution, plain DIP liposomes (PDL) and anchored DIP liposomes (ODL) against irradiation, disperse medium, biofluid, long-term storage were determined and compared. The concentrations of DIP in plasma of rats and its pharmacokinetic behaviors after intravenous administration of DIP injection, PDL and ODL were studied by RP-HPLC. The pharmacokinetic parameters were computed by software 3p97 programme. The results showed that ODL could increase stabilities more of DIP in vitro as compared with PDL. The plasma concentration-time curves of DIP after intravenous administration of DIP injection, PDL and ODL were all in accordance with open two-compartment model. Pharmacokinetic parameters of DIP injection, PDL and ODL in rats were significantly different. The present findings suggest that anchored liposomes could increase stabilities of DIP in vitro as compared with plain liposomes. Furthermore, the difference of pharmacokinetic profiles was due to the targetability of anchored liposomes. PMID:16540271

  15. A Validated Stability-Indicating Liquid-Chromatographic Method for Ranitidine Hydrochloride in Liquid Oral Dosage Form

    PubMed Central

    Sharma, Nitish; Rao, Surendra Singh; Kumar, Namala Durga Atchuta; Reddy, Pingili Sunil; Reddy, Annarapu Malleswara

    2011-01-01

    A selective, specific and stability-indicating gradient reverse phase high-performance liquid chromatographic (HPLC) method was developed for the determination of Ranitidine in presence of its impurities, forced degradation products and placebo substances such as saccharide and parabens. Ultraviolet detection was performed at 230 nm. Separate portions of the drug product and ingredients were exposed to stress conditions to induce oxidative, acidic, basic, hydrolytic, thermal and photolytic degradation. Ranitidine was found to degrade significantly at acidic, basic and oxidative stress conditions but was stable at heat and humidity. The developed method was validated as per International Conference on Harmonization (ICH) guidelines. The method was validated over this range for (i) system suitability (ii) specificity, (iii) precision, (iv) limit of detection and limit of quantification, (v) linearity, (vi) accuracy, (vii) robustness. The method was found to be precise, accurate, linear and robust. The proposed method was successfully employed for estimation of Ranitidine impurities in pharmaceutical preparations. PMID:21773068

  16. Stability indicating validated HPLC method for quantification of levothyroxine with eight degradation peaks in the presence of excipients.

    PubMed

    Shah, R B; Bryant, A; Collier, J; Habib, M J; Khan, M A

    2008-08-01

    A simple, sensitive, accurate, and robust stability indicating analytical method is presented for identification, separation, and quantitation of l-thyroxine and eight degradation impurities with an internal standard. The method was used in the presence of commonly used formulation excipients such as butylated hydroxyanisole, povidone, crospovidone, croscarmellose sodium, mannitol, sucrose, acacia, lactose monohydrate, confectionary sugar, microcrystalline cellulose, sodium laurel sulfate, magnesium stearate, talc, and silicon dioxide. The two active thyroid hormones: 3,3',5,5'-tetra-iodo-l-thyronine (l-thyroxine-T4) and 3,3',5-tri-iodo-l-thyronine (T3) and degradation products including di-iodothyronine (T2), thyronine (T0), tyrosine (Tyr), di-iodotyrosine (DIT), mono-iodotyrosine (MIT), 3,3',5,5'-tetra-iodothyroacetic acid (T4AA) and 3,3',5-tri-iodothyroacetic acid (T3AA) were assayed by the current method. The separation of l-thyroxine and eight metabolites along with theophylline (internal standard) was achieved using a C18 column (25 degrees C) with a mobile phase of trifluoroacetic acid (0.1%, v/v, pH 3)-acetonitrile in gradient elution at 0.8 ml/min at 223 nm. The sample diluent was 0.01 M methanolic NaOH. Method was validated according to FDA, USP, and ICH guidelines for inter-day accuracy, precision, and robustness after checking performance with system suitability. Tyr (4.97 min), theophylline (9.09 min), MIT (9.55 min), DIT (11.37 min), T0 (11.63 min), T2 (14.47 min), T3 (16.29 min), T4 (17.60 min), T3AA (22.71 min), and T4AA (24.83 min) separated in a single chromatographic run. Linear relationship (r2>0.99) was observed between the peak area ratio and the concentrations for all of the compounds within the range of 2-20 microg/ml. The total time for analysis, equilibration and recovery was 40 min. The method was shown to separate well from commonly employed formulation excipients. Accuracy ranged from 95 to 105% for T4 and 90 to 110% for all other compounds. Precision was <2% for all the compounds. The method was found to be robust with minor changes in injection volume, flow rate, column temperature, and gradient ratio. Validation results indicated that the method shows satisfactory linearity, precision, accuracy, and ruggedness and also stress degradation studies indicated that the method can be used as stability indicating method for l-thyroxine in the presence of excipients. PMID:18524511

  17. Stability-indicating ultra-performance liquid chromatography method for the estimation of thymoquinone and its application in biopharmaceutical studies.

    PubMed

    Pathan, Shadab A; Jain, Gaurav K; Zaidi, Syed M A; Akhter, Sohail; Vohora, Divya; Chander, Prakash; Kole, Prashant L; Ahmad, Farhan J; Khar, Roop K

    2011-05-01

    Thymoquinone (THQ) is known for its neuroprotective and anti-convulsant properties in preclinical studies. We herewith describe a simple, rapid, selective, sensitive and stability-indicating UPLC method for the estimation of THQ and its application to biopharmaceutical studies such as in vitro release from nanoparticulate system and in vivo pharmacokinetic study. The method employed gradient elution using a Waters Acquity HSS-T3 C(18) (100 × 2.1?mm, 1.8?µm) UPLC column. The mobile phase consisted of water and acetonitrile, pumped at a flow rate of 0.5?mL/min. The injection volume was 5?µL and THQ was monitored at 294?nm wavelength with a total run time of 6?min. In solution as well as in plasma, the method was found to be linear (r ? 0.998), precise (CV ? 2.45%) and accurate (recovery ? 84.8%) in the selected concentration range of 0.1-0.8?µg/mL. Forced degradation studies revealed that THQ undergoes degradation under acidic, basic, oxidation and UV light stress conditions. However, the developed UPLC method could effectively resolve degradation product peaks from THQ. Further, no interference was found at the retention time of THQ from any plasma components, indicating selectivity of the developed method. For solutions, the limits of detection and quantitation of the method were found to be 0.001 and 0.0033?µg/mL, respectively; while in plasma they were 0.006 and 0.02?µg/mL, respectively. The validated method was successfully applied to quantify THQ in dissolution medium as well as oral in vivo pharmacokinetic study of THQ suspension and THQ- solid lipid nanoparticle (THQ-SLN) formulation. A 2-fold increase in the relative bioavailability was observed with the THQ-SLN compared with THQ. The results indicate that the SLN significantly increased plasma concentrations and retention within the systemic circulation. PMID:20734352

  18. Folding Properties of Cytosine Monophosphate Kinase from E. coli Indicate Stabilization through an Additional Insert in the NMP Binding Domain

    PubMed Central

    Beitlich, Thorsten; Lorenz, Thorsten; Reinstein, Jochen

    2013-01-01

    The globular 25 kDa protein cytosine monophosphate kinase (CMPK, EC ID: 2.7.4.14) from E. coli belongs to the family of nucleoside monophosphate (NMP) kinases (NMPK). Many proteins of this family share medium to high sequence and high structure similarity including the frequently found ?/? topology. A unique feature of CMPK in the family of NMPKs is the positioning of a single cis-proline residue in the CORE-domain (cis-Pro124) in conjunction with a large insert in the NMP binding domain. This insert is not found in other well studied NMPKs such as AMPK or UMP/CMPK. We have analyzed the folding pathway of CMPK using time resolved tryptophan and FRET fluorescence as well as CD. Our results indicate that unfolding at high urea concentrations is governed by a single process, whereas refolding in low urea concentrations follows at least a three step process which we interpret as follows: Pro124 in the CORE-domain is in cis in the native state (Nc) and equilibrates with its trans-isomer in the unfolded state (Uc - Ut). Under refolding conditions, at least the Ut species and possibly also the Uc species undergo a fast initial collapse to form intermediates with significant amount of secondary structure, from which the trans-Pro124 fraction folds to the native state with a 100-fold lower rate constant than the cis-Pro124 species. CMPK thus differs from homologous NMP kinases like UMP/CMP kinase or AMP kinase, where folding intermediates show much lower content of secondary structure. Importantly also unfolding is up to 100-fold faster compared to CMPK. We therefore propose that the stabilizing effect of the long NMP-domain insert in conjunction with a subtle twist in the positioning of a single cis-Pro residue allows for substantial stabilization compared to other NMP kinases with ?/? topology. PMID:24205218

  19. Robust and Rugged Stability-Indicating HPLC Method for the Determination of Plerixafor and Its Related Impurities in Drug Substances.

    PubMed

    Bapatu, Hanimi Reddy; Maram, Ravi Kumar; Murthy, R Satyanarayana

    2015-10-01

    A novel, reversed-phase high-performance liquid chromatographic method was developed and validated for the determination of related substances in Plerixafor (PLX) drug substance. PLX is an immunostimulant used to mobilize hematopoietic stem cells in cancer patients. The method is efficient for estimation of all degradation and process-related impurities. The method was developed using the Phenomenex Luna L11 column using the gradient program with mobile phase A and mobile phase B, where mobile phase A consists of pH 2.0 1-heptanesulfonic acid sodium salt buffer and acetonitrile in the ratio of 80:20 (v/v) and mobile phase B consists of pH 2.0 1-heptanesulfonic acid sodium salt buffer and acetonitrile in the ratio of 20:80 (v/v). PLX and its impurities were monitored at 210 nm. The present work is describing the role of ion-pair reagent in the separation of polar compounds. PLX was subjected to various stress conditions of oxidative, acid, base, hydrolytic, thermal, humidity and photolytic degradations. The degradation products were well separated from each other and with the main peak, demonstrating the stability-indicating power of the method. The performance of the method was validated according to the present ICH guidelines for specificity, limit of detection, limit of quantification, linearity, accuracy, precision, ruggedness and robustness. PMID:25858970

  20. Stability-indicating LC-UV method for the determination of eszopiclone and degradation impurities in tablet dosage form.

    PubMed

    Shaikh, Kabeer; Patil, Ashish; Gite, Sandeep

    2014-04-01

    A sensitive, stability-indicating reversed-phase high-performance liquid chromatographic method was developed for the determination of eszopiclone and related impurities in tablet dosage form. The chromatographic separation was achieved on an Inertsil C18 column (250 × 4.6 mm, 5 µm), using a mobile phase consisting of 0.05M monobasic sodium phosphate buffer containing 0.8% sodium lauryl sulfate (pH 3.5) and acetonitrile in the ratio of 60:40 (v/v), at a flow rate of 1.5 mL/min and temperature of 40°C. Quantification was achieved with photodiode array detection at 303 nm. The described method showed excellent linearity over a range of limits of quantification to 4.8 µg/mL (150% of specification limit; i.e., 3.2 µg/mL). The drug product was subjected to the stress conditions of oxidative, acid, base, thermal and photolytic degradation. Eszopiclone degradation was observed in acid hydrolysis, base hydrolysis and peroxide stress conditions. Eszopiclone was stable in thermal and photolytic degradation conditions. The developed method is simple, selective and accurate for the quantification of impurities and degradation products of eszopiclone in tablet dosage form. PMID:23552846

  1. Stability-indicating HPLC assay for lysine-proline-valine (KPV) in aqueous solutions and skin homogenates.

    PubMed

    Pawar, Kasturi R; Mulabagal, Vanisree; Smith, Forrest; Kolli, Chandra S; Rangari, Vijaya K; Babu, R Jayachandra

    2015-05-01

    A simple, sensitive and stability-indicating high-performance liquid chromatographic (HPLC) assay method was developed and validated for a bioactive peptide, lysine-proline-valine (KPV) in aqueous solutions and skin homogenates. Chromatographic separation was achieved on a reversed phase Phenomenex C18 column (4.6 × 250 mm, packed with 5 µm silica particles) with a gradient mobile phase consisting of 0.1% trifluoroacetic acid (TFA) in water (A) and 0.1% TFA in acetonitrile (B). The proposed HPLC method was validated with respect to accuracy, precision, linearity, repeatability, limit of detection (LOD) and limit of quantitation (LOQ). The calibration curve was linear with a correlation coefficient (r) of 0.9999. Relative standard deviation values of accuracy and precision experiments were <2. The LOD and LOQ of KPV were 0.01 and 0.25 µg/mL, respectively. Under stress conditions (acid, alkali and hydrogen peroxide) KPV yielded lys-pro-diketopiperazine as major degradation product, which was identified by flow injection MS analysis. The developed HPLC method was found to be efficient in separating the active peptide from its degradation products generated under various stress conditions. Also, the validated method was able to separate KPV from other peaks arising from endogenous components of the skin homogenate. PMID:25298219

  2. Quantification of halobetasol propionate and its impurities present in topical dosage forms by stability-indicating LC method.

    PubMed

    Nalwade, Santaji; Reddy, Vangala Ranga; Kulkarni, Dipak; Todamal, Sandip

    2015-01-01

    A novel, sensitive, stability-indicating, gradient, reverse-phase high-performance liquid chromatographic method has been developed for quantitative determination of halobetasol propionate and its impurities in topical dosage forms. The chromatographic separation was achieved on a Phenomenex Synergi polar reverse phase, 250 × 4.6 mm, 4 µm column. Mobile phase A comprises a mixture of 0.01 M KH2PO4 buffer containing 0.2% 1-octane sulfonic acid sodium salt (pH 3.0), acetonitrile and methanol in the ratio 80:15:05 (v/v/v), respectively, and mobile phase B contains a mixture of 0.01 M KH2PO4 buffer containing 0.2% 1-octane sulfonic acid sodium salt (pH 3.0), acetonitrile and methanol in the ratio 20:70:10 (v/v/v), respectively. The flow rate is 0.8 mL min(-1). The column compartment temperature is set at 40°C and the detection wavelength is set at 240 nm. The resolutions between Halobetasol propionate and all the impurities are >2.0 for all pairs of compounds. The drug product was subjected to International Conference on Harmonization (ICH)-prescribed hydrolytic, oxidative, photolytic and thermal stress conditions. The method is validated as per the ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision, robustness and ruggedness. PMID:24784115

  3. Development of a validated stability-indicating HPTLC method for rufinamide in bulk and its pharmaceutical dosage form.

    PubMed

    Patel, Apexa; Patwari, Arpit; Suhagia, Bhanubhai

    2014-01-01

    A sensitive, selective, precise and stability indicating a high-performance thin layer chromatographic method for the analysis of rufinamide (Rf) in bulk drug and its formulations was developed and validated. The method employed thin layer chromatography aluminum plates precoated with silica gel 60 F254 as the stationary phase. The solvent system consisted of chloroform : methanol : glacial acetic acid (9 : 1 : 0.1 v/v/v). This system was found to give compact spots for Rf (Rf value of 0.68 ± 0.02). Rf was subjected to acid and alkali hydrolysis, oxidation, photodegradation and dry heat treatment. Also, the degraded products were well separated from the pure drug. Densitometric analysis of Rf was carried out in the absorbance mode at 210 nm, which is wavelength maxima for the degradant. The linear regression data for the calibration plots showed a good linear relationship with an r(2) of 0.9989 in the concentration range of 1,000-3,500 ng. The method was validated for precision, accuracy, ruggedness and recovery. The limits of detection and quantitation were 196.59 and 595.74 ng spot(-1), respectively. The drug undergoes degradation under acidic and basic conditions. All the peaks of degraded products were resolved from the standard drug with significantly different Rf values. PMID:24297523

  4. Measuring sperm whales from their clicks: Stability of interpulse intervals and validation that they indicate whale length

    NASA Astrophysics Data System (ADS)

    Rhinelander, Marcus Q.; Dawson, Stephen M.

    2004-04-01

    Multiple pulses can often be distinguished in the clicks of sperm whales (Physeter macrocephalus). Norris and Harvey [in Animal Orientation and Navigation, NASA SP-262 (1972), pp. 397-417] proposed that this results from reflections within the head, and thus that interpulse interval (IPI) is an indicator of head length, and by extrapolation, total length. For this idea to hold, IPIs must be stable within individuals, but differ systematically among individuals of different size. IPI stability was examined in photographically identified individuals recorded repeatedly over different dives, days, and years. IPI variation among dives in a single day and days in a single year was statistically significant, although small in magnitude (it would change total length estimates by <3%). As expected, IPIs varied significantly among individuals. Most individuals showed significant increases in IPIs over several years, suggesting growth. Mean total lengths calculated from published IPI regressions were 13.1 to 16.1 m, longer than photogrammetric estimates of the same whales (12.3 to 15.3 m). These discrepancies probably arise from the paucity of large (12-16 m) whales in data used in published regressions. A new regression is offered for this size range.

  5. Development and Validation of a Stability-Indicating Liquid Chromatographic Method for Estimating Olmesartan Medoxomil Using Quality by Design.

    PubMed

    Beg, Sarwar; Sharma, Gajanand; Katare, O P; Lohan, Shikha; Singh, Bhupinder

    2015-08-01

    The current studies entail systematic quality by design (QbD)-based development of a simple, rapid, sensitive and cost-effective stability-indicating method for the estimation of olmesartan medoxomil. Quality target method profile was defined and critical analytical attributes (CAAs) for the reverse-phase liquid chromatography method earmarked. Chromatographic separation accomplished on a C18 column using acetonitrile and water (containing 0.1% orthophosphoric acid, pH 3.5) in 40 : 60 (v/v) as mobile phase at a flow rate of 1.0 mL/min with UV detection at 243 nm. Risk assessment studies and screening studies facilitated comprehensive understanding of the factors affecting CAAs. The mobile phase ratio and flow rate were identified as critical method parameters (CMPs) and were systematically optimized using face-centered cubic design, evaluating for CAAs, namely peak area, retention time, theoretical plates and peak tailing. Statistical modelization was accomplished followed by response surface analysis for comprehending plausible interaction(s) among CMPs. Search for optimum solution was conducted through numerical and graphical optimization for demarcating the design space. Analytical method validation and subsequent forced degradation studies corroborated the method to be highly efficient for routine analysis of drug and its degradation products. The studies successfully demonstrate the utility of QbD approach for developing the highly sensitive liquid chromatographic method with enhanced method performance. PMID:25583970

  6. Validation of a high performance liquid chromatography method for the stabilization of epigallocatechin gallate.

    PubMed

    Fangueiro, Joana F; Parra, Alexander; Silva, Amélia M; Egea, Maria A; Souto, Eliana B; Garcia, Maria L; Calpena, Ana C

    2014-11-20

    Epigallocatechin gallate (EGCG) is a green tea catechin with potential health benefits, such as anti-oxidant, anti-carcinogenic and anti-inflammatory effects. In general, EGCG is highly susceptible to degradation, therefore presenting stability problems. The present paper was focused on the study of EGCG stability in HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid) medium regarding the pH dependency, storage temperature and in the presence of ascorbic acid a reducing agent. The evaluation of EGCG in HEPES buffer has demonstrated that this molecule is not able of maintaining its physicochemical properties and potential beneficial effects, since it is partially or completely degraded, depending on the EGCG concentration. The storage temperature of EGCG most suitable to maintain its structure was shown to be the lower values (4 or -20 °C). The pH 3.5 was able to provide greater stability than pH 7.4. However, the presence of a reducing agent (i.e., ascorbic acid) was shown to provide greater protection against degradation of EGCG. A validation method based on RP-HPLC with UV-vis detection was carried out for two media: water and a biocompatible physiological medium composed of Transcutol®P, ethanol and ascorbic acid. The quantification of EGCG for purposes, using pure EGCG, requires a validated HPLC method which could be possible to apply in pharmacokinetic and pharmacodynamics studies. PMID:25175728

  7. Stability indicating spectrophotometric and spectrodensitometric methods for the determination of diatrizoate sodium in presence of its degradation product

    NASA Astrophysics Data System (ADS)

    Abd El-Rahman, Mohamed K.; Riad, Safaa M.; Abdel Gawad, Sherif A.; Fawaz, Esraa M.; Shehata, Mostafa A.

    2015-02-01

    Three sensitive, selective, and precise stability indicating methods for the determination of the X-ray contrast agent, diatrizoate sodium (DTA), in the presence of its acidic degradation product (highly cytotoxic 3,5 diamino metabolite) and in pharmaceutical formulation were developed and validated. The first method is a first derivative (D1) spectrophotometric one, which allows the determination of DTA in the presence of its degradate at 231.2 nm (corresponding to zero crossing of the degradate) over a concentration range of 2-24 ?g/mL with mean percentage recovery 99.95 ± 0.97%. The second method is the first derivative of the ratio spectra (DD1) by measuring the peak amplitude at 227 nm over the same concentration range as D1 spectrophotometric method, with mean percentage recovery 99.99 ± 1.15%. The third method is a TLC-densitometric one, where DTA was separated from its degradate on silica gel plates using chloroform:methanol:ammonium hydroxide (20:10:2 by volume) as a developing system. This method depends on quantitative densitometric evaluation of thin layer chromatogram of DTA at 238 nm over a concentration range of 4-20 ?g/spot, with mean percentage recovery 99.88 ± 0.89%. The selectivity of the proposed methods was tested using laboratory-prepared mixtures. The proposed methods have been successfully applied to the analysis of DTA in pharmaceutical dosage forms without interference from other dosage form additives. The results were statistically compared with the official US pharmacopeial method. No significant difference for either accuracy or precision was observed.

  8. A Stability-Indicating HPLC Method for the Determination of Nitrosylcobalamin (NO-Cbl), a Novel Vitamin B12 Analog.

    PubMed

    Dunphy, Michael J; Sysel, Annette M; Lupica, Joseph A; Griffith, Kristie; Sherrod, Taylor; Bauer, Joseph A

    2014-04-01

    Nitrosylcobalamin (NO-Cbl), a novel vitamin B12 analog and anti-tumor agent, functions as a biologic 'Trojan horse', utilizing the vitamin B12 transcobalamin II transport protein and cell surface receptor to specifically target cancer cells. a stability-indicating HPLC method was developed for the detection of NO-Cbl during forced degradation studies. This method utilized an ascentis(®) RP-amide (150 mm × 4.6 mm, 5 ?m) column at 35 °C with a mobile phase (1.0 mL min(-1)) combining a gradient of methanol and an acetate buffer at pH 6.0. Detection wavelengths of 450 and 254 nm were used to detect corrin and non-corrin-based products, respectively. NO-Cbl, synthesized from hydroxocobalamin and pure nitric oxide gas, was subjected to degradative stress conditions including oxidation, hydrolysis and thermal and radiant energy challenge. The method was validated by assessing linearity, accuracy, precision, detection and quantitation limits and robustness. The method was applied successfully for purity assessment of synthesized NO-Cbl and for the determination of NO-Cbl during kinetic studies in aqueous solution and in solid-state degradation assessments. This HPLC method is suitable for the separation of cobalamins in aqueous and methanolic solutions, for routine detection of NO-Cbl and for purity assessment of synthesized NO-Cbl. additionally, this method has potential application in identification and monitoring of diseases involving altered nitric oxide homeostasis where vitamin B12 therapy is utilized to scavenge excess nitric oxide, subsequently resulting in the in vivo production of NO-Cbl. PMID:24855323

  9. A Stability-Indicating HPLC Method for the Determination of Nitrosylcobalamin (NO-Cbl), a Novel Vitamin B12 Analog

    PubMed Central

    Dunphy, Michael J.; Sysel, Annette M.; Lupica, Joseph A.; Griffith, Kristie; Sherrod, Taylor

    2014-01-01

    Nitrosylcobalamin (NO-Cbl), a novel vitamin B12 analog and anti-tumor agent, functions as a biologic ‘Trojan horse’, utilizing the vitamin B12 transcobalamin II transport protein and cell surface receptor to specifically target cancer cells. a stability-indicating HPLC method was developed for the detection of NO-Cbl during forced degradation studies. This method utilized an ascentis® RP-amide (150 mm × 4.6 mm, 5 ?m) column at 35 °C with a mobile phase (1.0 mL min?1) combining a gradient of methanol and an acetate buffer at pH 6.0. Detection wavelengths of 450 and 254 nm were used to detect corrin and non-corrin-based products, respectively. NO-Cbl, synthesized from hydroxocobalamin and pure nitric oxide gas, was subjected to degradative stress conditions including oxidation, hydrolysis and thermal and radiant energy challenge. The method was validated by assessing linearity, accuracy, precision, detection and quantitation limits and robustness. The method was applied successfully for purity assessment of synthesized NO-Cbl and for the determination of NO-Cbl during kinetic studies in aqueous solution and in solid-state degradation assessments. This HPLC method is suitable for the separation of cobalamins in aqueous and methanolic solutions, for routine detection of NO-Cbl and for purity assessment of synthesized NO-Cbl. additionally, this method has potential application in identification and monitoring of diseases involving altered nitric oxide homeostasis where vitamin B12 therapy is utilized to scavenge excess nitric oxide, subsequently resulting in the in vivo production of NO-Cbl. PMID:24855323

  10. Genetic variants of human serum albumin: molecular defects and biological stability.

    PubMed

    Galliano, M; Rossi, A; Porta, F; Minchiotti, L

    1995-01-01

    Because of recent studies, more heritable structural variants of serum albumin are known than for any other human protein except haemoglobin. However, alloalbumins are benign and thus they are detected only by screening of blood proteins in studies of population genetics or during routine clinical electrophoresis. We report the results of a collaborative study undertaken on genetic variants to define the structural changes and correlate these with the molecular properties of albumin. Our strategy consists in CNBr cleavage of the alkylated purified variants followed by isoelectric focusing (IEF) analysis to identify the fragment in which the substitution occurs. The abnormal peptide is then purified and digested with trypsin or V8 protease. A map of the digests is obtained by Rp-HPLC, the variant peptide is purified, and its amino-acid composition and sequence are determined. This procedure has so far allowed the identification of the molecular defects in 20 among the 26 alloalbumins detected in Italy. In the present study the mutations of the characterized variants are correlated with their frequency, geographic distribution, and biological stability. Point mutations, with only a few exceptions which are discussed, do not affect the stability of the protein. Alterations at the N-terminal, as in the case of proalbumins or Arg-Albumin, and extensive modifications at the C-terminal of the molecule, as well as changes involving the disulfide bridges, reduce the amount of the circulating protein. PMID:8593973

  11. Stress tensor: A quantitative indicator of effective volume and stability of helium in metals This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-print Network

    Simons, Jack

    Stress tensor: A quantitative indicator of effective volume and stability of helium in metals.1209/0295-5075/96/66001 Stress tensor: A quantitative indicator of effective volume and stability of helium in metals H.-B. Zhou1 demonstrate a quantitative stress indicator as well as a qualitative hard-sphere lattice model to characterize

  12. Engineering deamidation-susceptible asparagines leads to improved stability to thermal cycling in a lipase

    PubMed Central

    Bhanuramanand, K; Ahmad, Shoeb; Rao, N M

    2014-01-01

    At high temperatures, protein stability is influenced by chemical alterations; most important among them is deamidation of asparagines. Deamidation kinetics of asparagines depends on the local sequence, solvent, pH, temperature, and the tertiary structure. Suitable replacement of deamidated asparagines could be a viable strategy to improve deamidation-mediated loss in protein properties, specifically protein thermostability. In this study, we have used nano RP-HPLC coupled ESI MS/MS approach to identify residues susceptible to deamidation in a lipase (6B) on heat treatment. Out of 15 asparagines and six glutamines in 6B, only five asparagines were susceptible to deamidation at temperatures higher than 75°C. These five positions were subjected to site saturation mutagenesis followed by activity screen to identify the most suitable substitutions. Only three of the five asparagines were found to be tolerant to substitutions. Best substitutions at these positions were combined into a mutant. The resultant lipase (mutC) has near identical secondary structure and improved thermal tolerance as compared to its parent. The triple mutant has shown almost two-fold higher residual activity compared to 6B after four cycles at 90°C. MutC has retained more than 50% activity even after incubation at 100°C. Engineering asparagines susceptible to deamidation would be a potential strategy to improve proteins to withstand very high temperatures. PMID:25043738

  13. Chromium Oxidation State in Planetary Basalts: Oxygen Fugacity Indicator and Critical Variable for Cr-Spinel Stability

    NASA Technical Reports Server (NTRS)

    Bell, A. S.; Burger, P. V.; Le, Loan; Papike, J. J.; Jone, J.; Shearer, C. K.

    2014-01-01

    Cr is a ubiquitous and relatively abundant minor element in basaltic, planetary magmas. At the reduced oxidation states (stability and Cr concentration of magmatic phases such as spinel, clinopyroxene, and olivine. However, understanding the Cr valence in quenched melts has historically been plagued with analytical issues, and only recently has reliable methodology for quantifying Cr valence in quenched melts been developed. Despite this substantial difficulty, the pioneering works of Hanson and Jones and Berry and O'Neill provided important insights into the oxidation state of Cr in in silicate melts. Here we present a series of 1-bar gas mixing experiments performed with a Fe-rich basaltic melt in which have determined the Cr redox ratio of the melt at over a range of fO2 values by measuring this quantity in olivine with X-ray Absorption Near Edge Spectroscopy (XANES). The measured Cr redox ratio of the olivine phenocrysts can be readily converted to the ratio present in the conjugate melt via the ratio of crystal-liquid partition coefficients for Cr3+ and Cr2+. We have applied these results to modeling Cr spinel stability and Cr redox ratios in a primitive, iron-rich martian basalt.

  14. Improvement of a stability-indicating method by Quality-by-Design versus Quality-by-Testing: a case of a learning process.

    PubMed

    Hubert, C; Lebrun, P; Houari, S; Ziemons, E; Rozet, E; Hubert, Ph

    2014-01-01

    The understanding of the method is a major concern when developing a stability-indicating method and even more so when dealing with impurity assays from complex matrices. In the presented case study, a Quality-by-Design approach was applied in order to optimize a routinely used method. An analytical issue occurring at the last stage of a long-term stability study involving unexpected impurities perturbing the monitoring of characterized impurities needed to be resolved. A compliant Quality-by-Design (QbD) methodology based on a Design of Experiments (DoE) approach was evaluated within the framework of a Liquid Chromatography (LC) method. This approach allows the investigation of Critical Process Parameters (CPPs), which have an impact on Critical Quality Attributes (CQAs) and, consequently, on LC selectivity. Using polynomial regression response modeling as well as Monte Carlo simulations for error propagation, Design Space (DS) was computed in order to determine robust working conditions for the developed stability-indicating method. This QbD compliant development was conducted in two phases allowing the use of the Design Space knowledge acquired during the first phase to define the experimental domain of the second phase, which constitutes a learning process. The selected working condition was then fully validated using accuracy profiles based on statistical tolerance intervals in order to evaluate the reliability of the results generated by this LC/ESI-MS stability-indicating method. A comparison was made between the traditional Quality-by-Testing (QbT) approach and the QbD strategy, highlighting the benefit of this QbD strategy in the case of an unexpected impurities issue. On this basis, the advantages of a systematic use of the QbD methodology were discussed. PMID:24176744

  15. Improved efficiency and stability of secnidazole - An ideal delivery system.

    PubMed

    Khan, Salman; Haseeb, Mohd; Baig, Mohd Hassan; Bagga, Paramdeep Singh; Siddiqui, H H; Kamal, M A; Khan, Mohd Sajid

    2015-01-01

    Secnidazole (?,2-Dimethyl-5-nitro-1H-imidazole-1-ethanol) is a highly effective drug against a variety of G(+)/G(-) bacteria but with significant side effects because it is being used in very high concentration. In this study, gold nanoparticles (GNPS) were selected as a vehicle to deliver secnidazole drug at the specific site with more accuracy which made the drug highly effective at substantially low concentrations. The as-synthesized GNPs were capped with Human Serum Albumin (HSA) and subsequently bioconjugated with secnidazole because HSA provides the stability and improves the solubility of the bioconjugated drug, secnidazole. The quantification of covalently bioconjugated secnidazole with HSA encapsulated on enzymatically synthesized GNPs was done with RP-HPLC having SPD-20 A UV/VIS detector by using the C-18 column. The bioconjugation of GNPs with secnidazole was confirmed by Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS). The bioconjugated GNPs were characterized by UV-VIS spectroscopy, TEM, Scanning Electron Microscopy (SEM) and DLS. Zeta potential confirmed the stability and uniform distribution of particles in the emulsion of GNPs. The separation of bioconjugated GNPs, unused GNPs and unused drug was done by gel filtration chromatography. The minimal inhibitory concentration of secnidazole-conjugated gold nanoparticles (Au-HSA-Snd) against Klebsiella pneumonia (NCIM No. 2957) and Bacillus cereus (NCIM No. 2156) got improved by 12.2 times and 14.11 times, respectively, in comparison to pure secnidazole. Precisely, the MIC of Au-HSA-Snd against K. pneumonia (NCIM No. 2957) and B. cereus (NCIM No. 2156) were found to be 0.35 and 0.43 ?g/ml, respectively whereas MIC of the pure secnidazole drug against the same bacteria were found to be 4.3 and 6.07 ?g/ml, respectively. PMID:25561882

  16. Integrated Community Profiling Indicates Long-Term Temporal Stability of the Predominant Faecal Microbiota in Captive Cheetahs

    PubMed Central

    Becker, Anne A. M. J.; Janssens, Geert P. J.; Snauwaert, Cindy; Hesta, Myriam; Huys, Geert

    2015-01-01

    Understanding the symbiotic relationship between gut microbes and their animal host requires characterization of the core microbiota across populations and in time. Especially in captive populations of endangered wildlife species such as the cheetah (Acinonyx jubatus), this knowledge is a key element to enhance feeding strategies and reduce gastrointestinal disorders. In order to investigate the temporal stability of the intestinal microbiota in cheetahs under human care, we conducted a longitudinal study over a 3-year period with bimonthly faecal sampling of 5 cheetahs housed in two European zoos. For this purpose, an integrated 16S rRNA DGGE-clone library approach was used in combination with a series of real-time PCR assays. Our findings disclosed a stable faecal microbiota, beyond intestinal community variations that were detected between zoo sample sets or between animals. The core of this microbiota was dominated by members of Clostridium clusters I, XI and XIVa, with mean concentrations ranging from 7.5-9.2 log10 CFU/g faeces and with significant positive correlations between these clusters (P<0.05), and by Lactobacillaceae. Moving window analysis of DGGE profiles revealed 23.3-25.6% change between consecutive samples for four of the cheetahs. The fifth animal in the study suffered from intermediate episodes of vomiting and diarrhea during the monitoring period and exhibited remarkably more change (39.4%). This observation may reflect the temporary impact of perturbations such as the animal’s compromised health, antibiotic administration or a combination thereof, which temporarily altered the relative proportions of Clostridium clusters I and XIVa. In conclusion, this first long-term monitoring study of the faecal microbiota in feline strict carnivores not only reveals a remarkable compositional stability of this ecosystem, but also shows a qualitative and quantitative similarity in a defined set of faecal bacterial lineages across the five animals under study that may typify the core phylogenetic microbiome of cheetahs. PMID:25905625

  17. Integrated community profiling indicates long-term temporal stability of the predominant faecal microbiota in captive cheetahs.

    PubMed

    Becker, Anne A M J; Janssens, Geert P J; Snauwaert, Cindy; Hesta, Myriam; Huys, Geert

    2015-01-01

    Understanding the symbiotic relationship between gut microbes and their animal host requires characterization of the core microbiota across populations and in time. Especially in captive populations of endangered wildlife species such as the cheetah (Acinonyx jubatus), this knowledge is a key element to enhance feeding strategies and reduce gastrointestinal disorders. In order to investigate the temporal stability of the intestinal microbiota in cheetahs under human care, we conducted a longitudinal study over a 3-year period with bimonthly faecal sampling of 5 cheetahs housed in two European zoos. For this purpose, an integrated 16S rRNA DGGE-clone library approach was used in combination with a series of real-time PCR assays. Our findings disclosed a stable faecal microbiota, beyond intestinal community variations that were detected between zoo sample sets or between animals. The core of this microbiota was dominated by members of Clostridium clusters I, XI and XIVa, with mean concentrations ranging from 7.5-9.2 log10 CFU/g faeces and with significant positive correlations between these clusters (P<0.05), and by Lactobacillaceae. Moving window analysis of DGGE profiles revealed 23.3-25.6% change between consecutive samples for four of the cheetahs. The fifth animal in the study suffered from intermediate episodes of vomiting and diarrhea during the monitoring period and exhibited remarkably more change (39.4%). This observation may reflect the temporary impact of perturbations such as the animal's compromised health, antibiotic administration or a combination thereof, which temporarily altered the relative proportions of Clostridium clusters I and XIVa. In conclusion, this first long-term monitoring study of the faecal microbiota in feline strict carnivores not only reveals a remarkable compositional stability of this ecosystem, but also shows a qualitative and quantitative similarity in a defined set of faecal bacterial lineages across the five animals under study that may typify the core phylogenetic microbiome of cheetahs. PMID:25905625

  18. Stability-indicating micelle-enhanced spectrofluorimetric method for determination of loratadine and desloratadine in dosage forms.

    PubMed

    Walash, M I; Belal, F; El-Enany, N; Eid, M; El-Shaheny, R N

    2011-01-01

    A highly sensitive and simple spectrofluorimetric method was developed for the determination of loratadine (LRT) and desloratadine (DSL) in their pharmaceutical formulations. The proposed method is based on investigation of the fluorescence spectral behaviour of LRT and DSL in a sodium dodecyl sulphate (SDS) micellar system. In aqueous solution of acetate buffer of pH 4.5, the fluorescence intensities of both LRT and DSL were greatly enhanced (240%) in the presence of SDS. The fluorescence intensity was measured at 438 nm after excitation at 290 nm for both drugs. The fluorescence-concentration plots were rectilinear over the range 0.05-2.0 µg/mL for both LRT and DSL, with lower detection limits of 5.13 × 10(-3) and 6.35 × 10(-3) µg/mL for LRT and DSL, respectively. The method was successfully applied to the analysis of the two drugs in their commercial tablets, capsules and syrups, and the results were in good agreement with those obtained with the official or comparison methods. The proposed method is specific for the determination of LRT in the presence of other co-formulated drugs, such as pseudoephedrine. The application of the proposed method was extended to stability studies of LRT and DSL after exposure to different forced degradation conditions, such as acidic, alkaline and oxidative conditions, according to ICH guidelines. PMID:21491578

  19. A modeling approach to estimate the solar disinfection of viral indicator organisms in waste stabilization ponds and surface waters.

    PubMed

    Kohn, Tamar; Mattle, Michael J; Minella, Marco; Vione, Davide

    2016-01-01

    Sunlight is known to be a pertinent factor governing the infectivity of waterborne viruses in the environment. Sunlight inactivates viruses via endogenous inactivation (promoted by absorption of solar light in the UVB range by the virus) and exogenous processes (promoted by adsorption of sunlight by external chromophores, which subsequently generate inactivating reactive species). The extent of inactivation is still difficult to predict, as it depends on multiple parameters including virus characteristics, solution composition, season and geographical location. In this work, we adapted a model typically used to estimate the photodegradation of organic pollutants, APEX, to explore the fate of two commonly used surrogates of human viruses (coliphages MS2 and ?X174) in waste stabilization pond and natural surface water. Based on experimental data obtained in previous work, we modeled virus inactivation as a function of water depth and composition, as well as season and latitude, and we apportioned the contributions of the different inactivation processes to total inactivation. Model results showed that ?X174 is inactivated more readily than MS2, except at latitudes >60°. ?X174 inactivation varies greatly with both season (20-fold) and latitude (10-fold between 0 and 60°), and is dominated by endogenous inactivation under all solution conditions considered. In contrast, exogenous processes contribute significantly to MS2 inactivation. Because exogenous inactivation can be promoted by longer wavelengths, which are less affected by changes in season and latitude, MS2 exhibits smaller fluctuations in inactivation throughout the year (10-fold) and across the globe (3-fold between 0 and 60°) compared to ?X174. While a full model validation is currently not possible due to the lack of sufficient field data, our estimated inactivation rates corresponded well to those reported in field studies. Overall, this study constitutes a step toward estimating microbial water quality as a function of spatio-temporal information and easy-to-determine solution parameters. PMID:26615386

  20. Development and validation of a stability-indicating LC-UV method for the determination of pantethine and its degradation product based on a forced degradation study.

    PubMed

    Canavesi, Rossana; Aprile, Silvio; Varese, Elena; Grosa, Giorgio

    2014-08-01

    Pantethine (d-bis-(N-pantothenyl-?-aminoethyl)-disulfide, PAN), the stable disulfide form of pantetheine, has beneficial effects in vascular diseases being able to decrease the hyperlipidaemia, moderate the platelet function and prevent the lipid peroxidation. Furthermore, recent studies suggested that PAN may be an effective therapeutic agent for cerebral malaria and, possibly, for neurodegenerative processes. Interestingly, in the literature, there were no data dealing with the chemical stability and the analytical aspects of PAN. Hence, in the present work the chemical stability of PAN was for the first time established through a forced degradation study followed by liquid chromatography tandem mass spectrometry investigation showing the formation of three degradation products of PAN (PD1, PD2 and POx) arising from hydrolytic, thermal and oxidative stresses. Based on these data a stability-indicating LC-UV method for simultaneous estimation of PAN, and its most relevant degradation product (PD1) was developed and validated; moreover the method allowed also the separation and the quantification of the preservative system, constituted by a paraben mixture. The method showed linearity for PAN (0.4-1.2mgmL(-1)), MHB, PHB (0.4-1.2?gmL(-1)) and PD1 (2.5-100?gmL(-1)); the precision, determined in terms of intra-day and inter-day precision, expressed as RSDs, were in the ranges 0.4-1.2 and 0.7-1.4, respectively. The method demonstrated to be accurate and robust; indeed the average recoveries were 100.2, 99.9, and 100.0% for PAN, MHB and PHB, respectively, and 99.9% for PD1. By applying small variations of the mobile phase composition, counter-ion concentration and pH the separation of analytes was not affected. Finally, the applicability of this method was evaluated analyzing the available commercial forms at release as well as during stability studies. PMID:24863372

  1. A stability-indicating high performance liquid chromatographic (HPLC) assay for the simultaneous determination of atorvastatin and amlodipine in commercial tablets.

    PubMed

    Mohammadi, A; Rezanour, N; Ansari Dogaheh, M; Ghorbani Bidkorbeh, F; Hashem, M; Walker, R B

    2007-02-01

    A simple, rapid, precise and accurate isocratic reversed-phase stability-indicating HPLC method was developed and validated for the simultaneous determination of atorvastatin (AT) and amlodipine (AM) in commercial tablets. The method has shown adequate separation for AM, AT from their associated main impurities and their degradation products. Separation was achieved on a Perfectsil Target ODS-3, 5 microm, 250 mm x 4.6 mm i.d. column using a mobile phase consisting of acetonitrile-0.025 M NaH(2)PO(4) buffer (pH 4.5) (55:45, v/v) at a flow rate of 1 ml/min and UV detection at 237 nm. The drugs were subjected to oxidation, hydrolysis, photolysis and heat to apply stress conditions. The linearity of the proposed method was investigated in the range of 2-30 microg/ml (r=0.9994) for AT and 1-20 microg/ml (r=0.9993) for AM. The limits of detection were 0.65 microg/ml and 0.35 microg/ml for AT and AM, respectively. The limits of quantitation were 2 microg/ml and 1 microg/ml for AT and AM, respectively. Degradation products produced as a result of stress studies did not interfere with the detection of AT and AM and the assay can thus be considered stability-indicating. PMID:17010681

  2. Nifedipine-loaded polymeric nanocapsules: validation of a stability-indicating HPLC method to evaluate the drug entrapment efficiency and in vitro release profiles.

    PubMed

    Granada, Andréa; Tagliari, Monika Piazzon; Soldi, Valdir; Silva, Marcos António Segatto; Zanetti-Ramos, Betina Ghiel; Fernandes, Daniel; Stulzer, Hellen Karine

    2013-01-01

    A simple stability-indicating analytical method was developed and validated to quantify nifedipine in polymeric nanocapsule suspensions; an in vitro drug release study was then carried out. The analysis was performed using an RP C18 column, UV-Vis detection at 262 nm, and methanol-water (70 + 30, v/v) mobile phase at a flow rate of 1.2 mL/min. The method was validated in terms of specificity, linearity and range, LOQ, accuracy, precision, and robustness. The results obtained were within the acceptable ranges. The nanocapsules, made of poly(epsilon-caprolactone), were prepared by the solvent displacement technique and showed high entrapment efficiency. The entrapment efficiency was 97.6 and 98.2% for the nifedipine-loaded polymeric nanocapsules prepared from polyvinyl alcohol (PVA) and Pluronic F68 (PF68), respectively. The particle size and zeta potential of nanocapsules were found to be influenced by the nature of the stabilizer used. The mean diameter and zeta potential for nanocapsules with PVA and PF68 were 290.9 and 179.9 nm, and -17.7 mV and -32.7 mV, respectively. The two formulations prepared showed a drug release of up to 70% over 4 days. This behavior indicates the viability of this drug delivery system for use as a controlled-release system. PMID:23767350

  3. Development and validation of a simple, sensitive, selective and stability-indicating RP-UPLC method for the quantitative determination of ritonavir and its related compounds.

    PubMed

    Koppala, Srinivasarao; Panigrahi, Bibhuranjan; Raju, S V N; Padmaja Reddy, K; Ranga Reddy, V; Anireddy, Jaya Shree

    2015-01-01

    A simple, sensitive, selective and reproducible stability-indicating ultra-performance liquid chromatographic method was developed for the quantitative determination of degradation products and process-related impurities of Ritonavir in a pharmaceutical dosage form. Chromatographic separation was achieved on a polar embedded Waters Acquity BEH Shield RP18 (100 × 2.1 mm, 1.7 ?m) column thermostated at 50°C under gradient elution by using a binary mixture of potassium dihydrogen phosphate (0.01 M, pH 3.5) and acetonitrile at a flow rate of 0.5 mL/min. Chromatogram was monitored at 240 nm using a photodiode array detector. The drug and its related impurities are eluted within 20 min. To prove the stability-indicating power of the method, the drug was subjected to hydrolytic (acid, alkaline and water), oxidative, photolytic and thermal stress conditions. The unknown degradants were identified by the LC-MS-MS method, which revealed protonated molecular ion peaks [M + H](+) at m/z 551.40 for hydrolytic degradants, and m/z 737.60 and m/z 753.40 for photolytic degradants. A plausible mechanism for the formation of degradation and process impurities was proposed. The performance of the method was validated according to the International Conference on Harmonization guidelines. PMID:25186277

  4. A Validated Stability-Indicating RP-UPLC Method for Simultaneous Determination of Desloratadine and Sodium Benzoate in Oral Liquid Pharmaceutical Formulations

    PubMed Central

    Kumar, Navneet; Sangeetha, Dhanaraj; Reddy, Pingili Sunil; Prakash, Lakkireddy

    2012-01-01

    A novel, sensitive and selective stability-indicating gradient reverse phase ultra performance liquid chromatographic method was developed and validated for the quantitative determination of desloratadine and sodium benzoate in pharmaceutical oral liquid formulation. The chromatographic separation was achieved on Acquity BEH C8 (100 mm × 2.1 mm) 1.7 ?m column by using mobile phase containing a gradient mixture of solvent A (0.05 M KH2PO4 and 0.07 M triethylamine, pH 3.0) and B (50:25:25 v/v/v mixture of acetonitrile, methanol and water) at flow rate of 0.4 mL/min. Column temperature was maintained at 40°C and detection was carried out at a wavelength of 272 nm. The described method shows excellent linearity over a range of 0.254 ?g/mL to 76.194 ?g/mL for desloratadine and 1.006 ?g/mL to 301.67 ?g/mL for sodium benzoate. The correlation coefficient for desloratadine and sodium benzoate was more than 0.999. To establish stability-indicating capability of the method, drug product was subjected to the stress conditions of acid, base, oxidative, hydrolytic, thermal and photolytic degradation. The degradation products were well resolved from desloratadine and sodium benzoate. The developed method was validated as per international ICH guidelines with respect to specificity, linearity, LOD, LOQ, accuracy, precision and robustness. PMID:22396911

  5. A Rapid, Stability Indicating RP-UPLC Method for Simultaneous Determination of Ambroxol Hydrochloride, Cetirizine Hydrochloride and Antimicrobial Preservatives in Liquid Pharmaceutical Formulation

    PubMed Central

    Trivedi, Rakshit Kanubhai; Patel, Mukesh C.; Jadhav, Sushant B.

    2011-01-01

    A stability indicating reversed phase ultra performance liquid chromatography (RP-UPLC) method was developed for simultaneous determination of ambroxol hydrochloride (AMB), cetirizine hydrochloride (CTZ), methylparaben (MP) and propylparaben (PP) in liquid pharmaceutical formulation. The desired chromatographic separation was achieved on an Agilent Eclipse plus C18, 1.8 ?m (50 × 2.1 mm) column using gradient elution at 237 nm detector wavelength. The optimized mobile phase consists of a mixture of 0.01 M phosphate buffer and 0.1 % triethylamine as a solvent-A and acetonitrile as a solvent-B. The developed method separates AMB, CTZ, MP and PP in presence of twelve known impurities/degradation products and one unknown degradation product within 3.5 min. Stability indicating capability was established by forced degradation experiments and seperation of known and unknown degradation products. The lower limit of quantification was established for AMB, CTZ, MP and PP. The developed RP-UPLC method was validated according to the International Conference on Harmonization (ICH) guidelines. This validated method is applied for simultaneous estimation of AMB, CTZ, MP and PP in commercially available syrup samples. Further, the method can be extended for estimation of AMB, CTZ, MP, PP and levo-cetirizine (LCTZ) in various commercially available dosage forms. PMID:21886901

  6. Advanced stability indicating chemometric methods for quantitation of amlodipine and atorvastatin in their quinary mixture with acidic degradation products.

    PubMed

    Darwish, Hany W; Hassan, Said A; Salem, Maissa Y; El-Zeany, Badr A

    2016-02-01

    Two advanced, accurate and precise chemometric methods are developed for the simultaneous determination of amlodipine besylate (AML) and atorvastatin calcium (ATV) in the presence of their acidic degradation products in tablet dosage forms. The first method was Partial Least Squares (PLS-1) and the second was Artificial Neural Networks (ANN). PLS was compared to ANN models with and without variable selection procedure (genetic algorithm (GA)). For proper analysis, a 5-factor 5-level experimental design was established resulting in 25 mixtures containing different ratios of the interfering species. Fifteen mixtures were used as calibration set and the other ten mixtures were used as validation set to validate the prediction ability of the suggested models. The proposed methods were successfully applied to the analysis of pharmaceutical tablets containing AML and ATV. The methods indicated the ability of the mentioned models to solve the highly overlapped spectra of the quinary mixture, yet using inexpensive and easy to handle instruments like the UV-VIS spectrophotometer. PMID:26513228

  7. Separation and Measurement of Plant Alkaloid Enantiomers by RP-HPLC Analysis of their Fmoc-Alanine Analogs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plants often synthesize secondary metabolites that are enantiomers. Enantiomers can cause very different physiological responses. Ammodendrine (1) and anabasine (2) are teratogens that can cause congenital malformations in livestock and enantiomeric forms of each have been found in Lupinus spp. an...

  8. Optimization and Validation of RP-HPLC-UV/Vis Method for Determination Phenolic Compounds in Several Personal Care Products

    PubMed Central

    Akkbik, Mohammed; Assim, Zaini Bin; Ahmad, Fasihuddin Badruddin

    2011-01-01

    An HPLC method with ultraviolet-visible spectrophotometry detection has been optimized and validated for the simultaneous determination of phenolic compounds, such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) as antioxidants, and octyl methyl cinnamate (OMC) as UVB-filter in several personal care products. The dynamic range was between 1 to 250?mg/L with relative standard deviation less than 0.25% (n = 4). Limits of detection for BHA, BHT, and OMC were 0.196, 0.170, and 0.478?mg/L, respectively. While limits of quantification for BHA, BHT, and OMC were 0.593, 0.515, and 1.448?mg/L, respectively. The recovery for BHA, BHT, and OMC was ranged from 92.1–105.9%, 83.2–108.9%, and 87.3–103.7%, respectively. The concentration ranges of BHA, BHT, and OMC in 12 commercial personal care samples were 0.13–4.85, 0.16–2.30, and 0.12–65.5?mg/g, respectively. The concentrations of phenolic compounds in these personal care samples were below than maximum allowable concentration in personal care formulation, that is, 0.0004–10?mg/g, 0.002–5?mg/g, and up to 100?mg/g for BHA, BHT, and OMC, respectively. PMID:21760792

  9. Determination of underivatized long chain fatty acids using RP-HPLC with capacitively coupled contactless conductivity detection.

    PubMed

    Makahleh, Ahmad; Saad, Bahruddin; Siang, Gan Hui; Saleh, Muhammad Idiris; Osman, Hasnah; Salleh, Baharuddin

    2010-04-15

    A reversed-phase high-performance liquid chromatographic method with capacitively coupled contactless conductivity detector (C(4)D) has been developed for the separation and the simultaneous determination of five underivatized long chain fatty acids (FAs), namely myristic, palmitic, stearic, oleic, and linoleic acids. An isocratic elution mode using methanol/1mM sodium acetate (78:22, v/v) as mobile phase with a flow rate of 0.6 mL min(-1) was used. The separation was effected by using a Hypersil ODS C(18) analytical column (250 mm x 4.6 mm x 5 microm) and was operated at 45 degrees C. Calibration curves of the five FAs were well correlated (r(2)>0.999) within the range of 5- 200 microg mL(-1) for stearic acid, and 2-200 microg mL(-1) for the other FAs. The proposed method was tested on four vegetable oils, i.e., pumpkin, soybean, rice bran and palm olein oils; good agreement was found with the standard gas chromatographic (GC) method. The proposed method offers distinct advantages over the official GC method, especially in terms of simplicity, faster separation times and sensitivity. PMID:20188881

  10. RP-HPLC Determination of Phenylalkanoids and Monoterpenoids in Rhodiola rosea and Identification by LC-ESI-TOF

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An HPLC method permitting the simultaneous determination of fourteen compounds (phenylalkanoids and monoterpenoids) from the roots of Rhodiola rosea was developed. A separation was achieved within 35 minutes by using C-18 column material, a water/acetonitrile mobile phase, both containing 0.05% phos...

  11. RP-HPLC analysis of phenolic compounds and flavonoids in beverages and plant extracts using a CoulArray detector.

    PubMed

    Jandera, Pavel; Skeifíková, Veronika; Rehová, Lucie; Hájek, Tomás; Baldriánová, Lucie; Skopová, Gabriela; Kellner, Vladimír; Horna, Ales

    2005-06-01

    Methods were developed for the analysis of natural antioxidants including phenolic compounds and flavonoids in beverages and plant extracts using gradient HPLC with multi-channel electrochemical coulometric detection. Suitability of various reversed-phase columns for this purpose was compared; pH and mobile phase gradients were optimized with respect to the separation selectivity and sensitivity of detection. Because of different target compounds in various sample types, the overlapping resolution maps and the normalized resolution product approaches described earlier were used to select optimum columns and gradients to suit the analysis of the individual sample types. The methods were applied to the analysis of phenolic compounds and flavonoids in beer, wine, tea, and yacon extracts. 32 phenolic compounds were identified and determined, including derivatives of benzoic and cinnamic acids, flavones, and a few related glycosides. Eight-channel CoulArray detection offers high selectivity and sensitivity with limits of detection in the low microg L(-1) range, at least an order of magnitude lower than single-channel coulometric detection using the Coulochem detector. No special sample pretreatment is necessary and, because of the compatibility of the CoulArray detector with gradient elution, phenolic antioxidants of different polarities can be determined in a single run. In addition to the retention times, the ratios of the areas of the pre-dominant and post-dominant peaks to the area of the dominant peak can be used for improved identification of natural antioxidants. PMID:16013828

  12. Simultaneous Determination of Six Active Compounds in Yixin Badiranjibuya Granules, a Traditional Chinese Medicine, by RP-HPLC-UV Method

    PubMed Central

    Yu, Ning; He, ChenHui; Awuti, Gulistan; Zeng, Cheng; Xing, JianGuo; Huang, Wei

    2015-01-01

    In this study, a sensitive, precise, and accurate HPLC-UV method was developed and validated to simultaneously determine the six analytes (luteolin-7-O-?-D-glucuronide, apigenin-7-O-?-D-glucuronide, diosmetin-7-O-?-D-glucuronide, acacetin-7-O-?-D-glucuronide, tilianin, and rosmarinic acid) in Yixin Badiranjibuya Granules, in which five analytes (i.e., luteolin-7-O-?-D-glucuronide, apigenin-7-O-?-D-glucuronide, diosmetin-7-O-?-D-glucuronide, acacetin-7-O-?-D-glucuronide, and rosmarinic acid) were determined for the first time in Yixin Badiranjibuya Granules, the content of tilianin in Yixin Badiranjibuya Granules was reported in other literatures, and the content of tilianin in our work was higher than that of the literature reports. The quality of 11 batch samples from four different manufacturers was evaluated using the proposed determination method. The contents of the six analytes were largely different among samples from various manufacturers. Therefore, this determination method can provide a scientific basis for quality evaluation and control of Yixin Badiranjibuya Granules. PMID:26587308

  13. A Validated RP-HPLC Method for the Analysis of 1-Fluoronaphthalene and Its Process-Related Impurities.

    PubMed

    Karagiannidou, Evrykleia G; Bekiari, Eleni T; Vastardi, Elli I

    2015-09-01

    A simple and precise reversed-phase high-performance liquid chromatography method was developed and validated for the determination of 1-fluoronaphthalene and its process-related impurities, 1-aminonaphthalene, 1-nitronaphthalene, naphthalene and 2-fluoronaphthalene. 1-Fluoronaphthalene is the key starting material for the synthesis of duloxetine hydrochloride active pharmaceutical ingredient and is therefore a potential impurity of the API. The determination of the impurity profile is critical for the safety assessment of a substance and manufacturing process thereof. In duloxetine hydrochloride active pharmaceutical ingredient, only 1-fluoronaphthalene is detected and neither of its related impurities of 1-aminonaphthalene, 1-nitronaphthalene, naphthalene and 2-fluoronaphthalene. Chromatography was carried out on a Symmetry C18 (250 × 4.6 mm, 5 ?m) column, using mobile phase A-a mixture of 0.01 ? KH2PO4 buffer (pH 2.5 ± 0.1):methanol:acetonitrile in the ratio of 35:52:13 v/v/v and mobile phase B-a mixture of methanol:acetonitrile in the ratio of 80:20 v/v at a flow rate of 1.0 mL/min. The analytes were monitored using photo diode array detector at 230 nm. The proposed method is found to be having linearity in the concentration of 0.075-5.000 ?g/mL, 0.150-5.000 ?g/mL, 0.3125-5.000 ?g/mL and 0.3125-5.000 ?g/mL for 1-aminonaphthalene, 1-nitronaphthalene, naphthalene and 2-fluoronaphthalene, respectively, with correlation coefficients of 0.9998, 0.9998, 0.9997 and 0.9997, respectively. The proposed method was validated as per the International Conference on Harmonization guidelines. The mean recoveries for all the studied impurities are in the range of 90-110%. Due to its specificity, high precision and accuracy, the developed method can be used for the determination of 1-fluoronaphthalene, key starting material for the synthesis of duloxetine hydrochloride API. PMID:25713107

  14. Development and validation of a fast RP-HPLC method for determination of methotrexate entrapment efficiency in polymeric nanocapsules.

    PubMed

    Sartori, Tatiane; Seigi Murakami, Fabio; Pinheiro Cruz, Ariane; Machado de Campos, Angela

    2008-07-01

    A rapid and effective isocratic chromatographic procedure is successfully developed to determinate methotrexate (MTX) entrapment efficiency (EE) in polymeric nanocapsules using reversed-phase high-performance liquid chromatography. The method employed a RP-C(18) Shimadzu Shim-pack CLC-ODS (150 mm x 4.6 mm, 5 microm) column with mobile phase constituted by a mixture of water-acetonitrile-tetrahydrofuran (65:30:5 v/v/v; pH 3.0) at a flow rate of 0.8 mL/min. The eluate is monitored with a UV detector set at 313 nm. The parameters used in the validation process are: linearity, specificity, precision, accuracy, and limit of quantitation (LOQ). The linearity is evaluated by a calibration curve in the concentration range of 10-50 microg/mL and presented a correlation coefficient of 0.9998. The polymers (PLA or PLA-PEG), oil, and surfactants used in the nanocapsule formulation did not interfere with analysis and the recovery was quantitative. The intra and inter-day assay relative standard deviation were less than 0.72%. Results are satisfactory, and the method proved to be adequate for the determination of methotrexate in nanocapsules formulations. PMID:18647471

  15. Simultaneous Determination of Fangchinoline and Tetrandrine in Qi-Fang-Xi-Bi-Granules by RP-HPLC.

    PubMed

    Lu, XinGang; Zhang, RuoXi; Fu, Feng; Shen, Jie; Nian, Hua; Wu, Tao

    2015-09-01

    Knee Osteoarthritis is one of the most common diseases of elder worldwide. Qi-Fang-Xi-Bi-Granules (QFXBG) is a new Chinese medicine granules employed for the treatment of Knee Osteoarthritis. Fangchinoline (FAN) and tetrandrine (TET) are used as targets of quality control of QFXBG. A simple, practical high-performance liquid chromatographic method was developed for the simultaneous quantitation of FAN and TET in Stephaniae tetrandrae radix and QFXBG. The analysis was performed on a Athena C18 column (250 × 4.6 mm, 5 µm) with mobile phase of methanol-water (65 : 35, v/v, pH 3.0, adjusted by glacial acetic acid) containing 1.0 g/L sodium 1-octanesulfonate. This method was validated in terms of linearity, precision, accuracy and recovery. Results showed that this method had good linearity with R(2) at >0.999. The limit of detection and limit of quantification for FAN were 0.13 and 0.35 mg/L, while for TET were 0.28 and 0.76 mg/L, respectively. The relative standard deviations of precision were 0.1-1.3% for intraday and 0.5-2.4% for interday. The recovery was 94.56-98.81% of FAN and 94.07-99.12% of TET, respectively. The chromatographic analytical time was 14 min. This method was successfully applied for the quantitative analysis of FAN and TET in Stephaniae tetrandrae radix and QFXBG, so that it could be extended to quality control of QFXGB in commercial. PMID:25754692

  16. Simple and Sensitive Stability-Indicating Ion Chromatography Method for the Determination of Cyclopropylamine in Nevirapine and Moxifloxacin Hydrochloride Drug Substances

    PubMed Central

    Kothapalli, Pavan Kumar S. R.; Khagga, Mukkanti; Mekala, Nageswara Rao; Sigamani, John Prasanna; Vundavilli, Jagadeesh Kumar; Masani, Narendra Kumar; Sharma, Hemant Kumar

    2012-01-01

    A simple and sensitive ion chromatography method has been developed for the determination of cyclopropylamine (CPA) in nevirapine (NEV) and moxifloxacin HCl (MOX) pharmaceutical drug substances. Efficient chromatographic separation was achieved on a Metrosep C4, 5 ?m (250 mm × 4.0 mm) column. The mobile phase consists of 5 mM hydrochloric acid containing 10% (v/v) acetonitrile and was delivered in an isocratic mode at a flow rate of 0.9 mL min?1 at 27°C. A conductometric detector was used for the detection of the analyte. The drug substances were subjected to stress conditions including oxidation, thermal, photolytic and humidity for the evaluation of the stability-indicating nature of the method. The method was validated for specificity, precision, linearity, accuracy and solution stability. The limit of detection (LOD) and limit of quantification (LOQ) values are 0.10 ?g mL?1 and 0.37 ?g mL?1 respectively. The linearity range of the method is between 0.37 ?g mL?1 and 1.5 ?g mL?1 and the correlation coefficient is found to be 0.9971. The average recoveries of CPA in NEV and MOX are 97.0% and 98.0%, respectively. PMID:22396905

  17. Simple and sensitive stability-indicating ion chromatography method for the determination of cyclopropylamine in nevirapine and moxifloxacin hydrochloride drug substances.

    PubMed

    Kothapalli, Pavan Kumar S R; Khagga, Mukkanti; Mekala, Nageswara Rao; Sigamani, John Prasanna; Vundavilli, Jagadeesh Kumar; Masani, Narendra Kumar; Sharma, Hemant Kumar

    2012-01-01

    A simple and sensitive ion chromatography method has been developed for the determination of cyclopropylamine (CPA) in nevirapine (NEV) and moxifloxacin HCl (MOX) pharmaceutical drug substances. Efficient chromatographic separation was achieved on a Metrosep C4, 5 ?m (250 mm × 4.0 mm) column. The mobile phase consists of 5 mM hydrochloric acid containing 10% (v/v) acetonitrile and was delivered in an isocratic mode at a flow rate of 0.9 mL min(-1) at 27°C. A conductometric detector was used for the detection of the analyte. The drug substances were subjected to stress conditions including oxidation, thermal, photolytic and humidity for the evaluation of the stability-indicating nature of the method. The method was validated for specificity, precision, linearity, accuracy and solution stability. The limit of detection (LOD) and limit of quantification (LOQ) values are 0.10 ?g mL(-1) and 0.37 ?g mL(-1) respectively. The linearity range of the method is between 0.37 ?g mL(-1) and 1.5 ?g mL(-1) and the correlation coefficient is found to be 0.9971. The average recoveries of CPA in NEV and MOX are 97.0% and 98.0%, respectively. PMID:22396905

  18. A Stability-Indicating HPLC-DAD Method for Determination of Ferulic Acid into Microparticles: Development, Validation, Forced Degradation, and Encapsulation Efficiency

    PubMed Central

    Toledo, Maria da Graça; Pupo, Yasmine Mendes; Padilha de Paula, Josiane; Zanin, Sandra Maria Warumby

    2015-01-01

    A simple stability-indicating HPLC-DAD method was validated for the determination of ferulic acid (FA) in polymeric microparticles. Chromatographic conditions consisted of a RP C18 column (250?mm × 4.60?mm, 5??m, 110?Å) using a mixture of methanol and water pH 3.0 (48?:?52?v/v) as mobile phase at a flow rate of 1.0?mL/min with UV detection at 320?nm. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of quantification, limit of detection, accuracy, precision, and robustness provided suitable results regarding all parameters investigated. The calibration curve was linear in the concentration range of 10.0–70.0??g/mL with a correlation coefficient >0.999. Precision (intraday and interday) was demonstrated by a relative standard deviation lower than 2.0%. Accuracy was assessed by the recovery test of FA from polymeric microparticles (99.02% to 100.73%). Specificity showed no interference from the components of polymeric microparticles or from the degradation products derived from acidic, basic, and photolytic conditions. In conclusion, the method is suitable to be applied to assay FA as bulk drug and into polymeric microparticles and can be used for studying its stability and degradation kinetics. PMID:26075139

  19. A comparative study between three stability indicating spectrophotometric methods for the determination of diatrizoate sodium in presence of its cytotoxic degradation product based on two-wavelength selection

    NASA Astrophysics Data System (ADS)

    Riad, Safaa M.; El-Rahman, Mohamed K. Abd; Fawaz, Esraa M.; Shehata, Mostafa A.

    2015-06-01

    Three sensitive, selective, and precise stability indicating spectrophotometric methods for the determination of the X-ray contrast agent, diatrizoate sodium (DTA) in the presence of its acidic degradation product (highly cytotoxic 3,5-diamino metabolite) and in pharmaceutical formulation, were developed and validated. The first method is ratio difference, the second one is the bivariate method, and the third one is the dual wavelength method. The calibration curves for the three proposed methods are linear over a concentration range of 2-24 ?g/mL. The selectivity of the proposed methods was tested using laboratory prepared mixtures. The proposed methods have been successfully applied to the analysis of DTA in pharmaceutical dosage forms without interference from other dosage form additives. The results were statistically compared with the official US pharmacopeial method. No significant difference for either accuracy or precision was observed.

  20. Stability-indicating reversed-phase HPLC method development and characterization of impurities in vortioxetine utilizing LC-MS, IR and NMR.

    PubMed

    Liu, Lei; Cao, Na; Ma, Xingling; Xiong, Kaihe; Sun, Lili; Zou, Qiaogen; Yao, Lili

    2016-01-01

    The current study reports the development and validation of a stability-indicating reversed phase HPLC method for the separation and identification of potential impurities in vortioxetine, a recently developed antidepressant. The structures of a new compound and four process-related impurities formed during the synthesis were characterized and confirmed by NMR, MS, and IR spectroscopy analyses. The most probable formation mechanisms of the impurities identified were proposed. Based on the characterization data, the new compound was proposed to be 1-[4-[(2,4-dimethylphenyl)thio]phenyl]-piperazine. In addition, an efficient chromatographic method was optimized to separate and quantify the impurities, which were obtained in the 0.05-0.75?g/mL range. The developed HPLC method was validated with respect to accuracy, precision, linearity, robustness, and limits of detection and quantitation. PMID:26412721

  1. Stability-indicating RP-LC method for determination of azilsartan medoxomil and chlorthalidone in pharmaceutical dosage forms: application to degradation kinetics.

    PubMed

    Ebeid, Walid M; Elkady, Ehab F; El-Zaher, Asmaa A; El-Bagary, Ramzia I; Patonay, Gabor

    2014-10-01

    A RP-LC method was developed and validated for simultaneous determination of the active components, azilsartan medoxomil (AZL) and chlorthalidone (CLT), in their novel antihypertensive combined recipe. The chromatographic separation was achieved on an Eclipse XDB-C18 (4.6?×?150 mm, 5 ?m) column using a mobile phase consisting of methanol/potassium hydrogen phosphate buffer (pH 8, 0.05 M) (40:60, v/v) in isocratic mode. The flow rate was maintained at 0.8 mL min(-1) at ambient temperature. Detection was carried out at 210 nm. The method was validated according to the ICH guidelines. Linearity, accuracy, and precision were satisfactory over the concentration range of 5.0-50.0 and 2.5-25.0 ?g mL(-1) for AZL and CLT, respectively (r (2)?=?0.9999). LODs for AZL and CLT were 0.90 and 0.32 ?g mL(-1), whereas LOQs were 2.72 and 0.98 ?g mL(-1), respectively. Both drugs were subjected to forced degradation studies under hydrolysis (neutral, acidic, and alkaline), oxidative, and photolytic extensive stress conditions. The proposed method is stability indicating by the resolution of the investigated drugs from their degradation products. Moreover, the kinetics of the acidic degradation of AZL as well as the kinetics of the alkaline degradation of CLT were investigated. Arrhenius plots were constructed and the apparent first-order rate constants, half-life times, shelf-life times, and the activation energies of the degradation processes were calculated. The method was successfully applied for the determination of the studied drugs simultaneously in their coformulated tablet. The developed method is specific and stability indicating for the quality control and routine analysis of the cited medications in their pharmaceutical preparations. PMID:25190009

  2. Stability indicating LC method for rapid determination of related substances of O-desmethyl venlafaxine in active pharmaceutical ingredients and pharmaceutical formulations.

    PubMed

    Rao, Karri Visweswara; Reddy, Kesareddy Padmaja; Kumar, Yelavarthi Ravindra

    2014-01-01

    A simple, precise and accurate stability-indicating reversed phase-high performance liquid chromatography method was developed for the quantitative determination of O-desmethyl venlafaxine (ODV) and its related substances in active pharmaceutical ingredient and pharmaceutical formulation. The method was developed using YMC-pack ODS-A (150 × 4.6 mm, 3 ?m) column with mobile phase containing a gradient mixture of solvents A and B. Solvent A contained a mixture of buffer and acetonitrile in the ratio of 85:15 (v/v). The buffer consisted of 10 mM potassium dihydrogen phosphate and 2 mM 1-octane sulfonic acid sodium salt (pH adjusted to 6.0 by using diluted potassium hydroxide solution). Solvent B contained a mixture of water and acetonitrile in the ratio of 20:80 (v/v). The eluted compounds were monitored at 230 nm. ODV and its six impurities were well separated within 14 min run time. It was subjected under the stress conditions of oxidative, acid, base, water, thermal and photolytic degradation. It was sensitive towards acidic, basic, oxidative and water stress conditions, stable in photolytic and thermal degradation conditions. The degradation products were well resolved from main peak and its impurities, the mass balance in each case was >99.0%, proving the stability-indicating power of the method. The developed method was validated as per International Conference on Harmonization (ICH) guidelines with respect to its specificity, linearity (correlation coefficient >0.9996), limit of detection, limit of quantification, accuracy (recovery range 97.1-103.2%), precision (% relative standard deviation ?1.9%) and robustness. PMID:24474426

  3. Development and validation of a rapid stability indicating HPLC-method using monolithic stationary phase and two spectrophotometric methods for determination of antihistaminic acrivastine in capsules

    NASA Astrophysics Data System (ADS)

    Gouda, Ayman A.; Hashem, Hisham; Jira, Thomas

    2014-09-01

    Simple, rapid and accurate high performance liquid chromatographic (HPLC) and spectrophotometric methods are described for determination of antihistaminic acrivastine in capsules. The first method (method A) is based on accurate, sensitive and stability indicating chromatographic separation method. Chromolith® Performance RP-18e column, a relatively new packing material consisting of monolithic rods of highly porous silica, was used as stationary phase applying isocratic binary mobile phase of ACN and 25 mM NaH2PO4 pH 4.0 in the ratio of 22.5:77.5 at flow rate of 5.0 mL/min and 40 °C. A diode array detector was used at 254 nm for detection. The elution time of acrivastine was found to be 2.080 ± 0.032. The second and third methods (methods B and C) are based on the oxidation of acrivastine with excess N-bromosuccinimide (NBS) and determination of the unconsumed NBS with, metol-sulphanilic acid (?max: 520 nm) or amaranth dye (?max: 530 nm). The reacted oxidant corresponds to the drug content. Beer’s law is obeyed over the concentration range 1.563-50, 2.0-20 and 1.0-10 ?g mL-1 for methods A, B and C, respectively. The limits of detection and quantitation were 0.40, 0.292 and 0.113 ?g mL-1 and 0.782, 0.973 and 0.376 ?g mL-1 for methods A, B and C, respectively. The HPLC method was validated for system suitability, linearity, precision, limits of detection and quantitation, specificity, stability and robustness. Stability tests were done through exposure of the analyte solution for four different stress conditions and the results indicate no interference of degradants with HPLC-method. The proposed methods was favorably applied for determination of acrivastine in capsules formulation. Statistical comparison of the obtained results from the analysis of the studied drug to those of the reported method using t- and F-tests showed no significant difference between them.

  4. Antioxidant responses to an acute ultra-endurance exercise: impact on DNA stability and indications for an increased need for nutritive antioxidants in the early recovery phase.

    PubMed

    Neubauer, Oliver; Reichhold, Stefanie; Nics, Lukas; Hoelzl, Christine; Valentini, Judit; Stadlmayr, Barbara; Knasmüller, Siegfried; Wagner, Karl-Heinz

    2010-10-01

    Antioxidant requirements have neither been defined for endurance nor been defined for ultra-endurance athletes. To verify whether an acute bout of ultra-endurance exercise modifies the need for nutritive antioxidants, we aimed (1) to investigate the changes of endogenous and exogenous antioxidants in response to an Ironman triathlon; (2) to particularise the relevance of antioxidant responses to the indices of oxidatively damaged blood lipids, blood cell compounds and lymphocyte DNA and (3) to examine whether potential time-points of increased susceptibility to oxidative damage are associated with alterations in the antioxidant status. Blood that was collected from forty-two well-trained male athletes 2 d pre-race, immediately post-race, and 1, 5 and 19 d later was sampled. The key findings of the present study are as follows: (1) Immediately post-race, vitamin C, ?-tocopherol, and levels of the Trolox equivalent antioxidant capacity, the ferric reducing ability of plasma and the oxygen radical absorbance capacity (ORAC) assays increased significantly. Exercise-induced changes in the plasma antioxidant capacity were associated with changes in uric acid, bilirubin and vitamin C. (2) Significant inverse correlations between ORAC levels and indices of oxidatively damaged DNA immediately and 1 d post-race suggest a protective role of the acute antioxidant responses in DNA stability. (3) Significant decreases in carotenoids and ?-tocopherol 1 d post-race indicate that the antioxidant intake during the first 24 h of recovery following an acute ultra-endurance exercise requires specific attention. Furthermore, the present study illustrates the importance of a diversified and well-balanced diet to maintain a physiological antioxidant status in ultra-endurance athletes in reference to recommendations. PMID:20637132

  5. Development of a stability-indicating HPLC method of etifoxine with characterization of degradation products by LC-MS/TOF, 1H and 13C NMR.

    PubMed

    Djabrouhou, Nadia; Guermouche, Moulay-Hassane

    2014-11-01

    This paper describes a new LC-MS/TOF method for the degradation products determination when Etifoxine (ETI) is submitted to different stress conditions. Chromatography is performed by using Kromasil C18 column (250mm×4.6mm, 5?m particle size). The selected mobile phase consists of formate buffer 0.02M, pH 3 and methanol (70/30, v/v). ETI is submitted to oxidative, acidic, basic, hydrolytic, thermal and UV light degradations. Detection is made at 254nm by photodiode array detector and mass spectrometry. A number of degradation products (DPs) called DPA, DPB, DPC and DPD are found depending on the stress; DPA with heat, DPA and DPB in acidic media or under UV-light; DPA, DPB and DPC under basic stress; DPA, DPB, DPC and DPD with oxidation. LC-MS/TOF is used to characterize the four DPs of ETI resulting from different stress conditions. (1)H and (13)C NMR are used to confirm the DP structures. The ETI fragmentation pathway is proposed. The method is validated with reference to International Conference on Harmonization guidelines and ETI are selectively determined in presence of its DPs, demonstrating its stability-indicating nature. Finally, for the validation step, specificity, linearity, accuracy and precision are determined for ETI and its DPs. PMID:25117950

  6. Development and validation of stability-indicating high performance liquid chromatography method to analyze gatifloxacin in bulk drug and pharmaceutical preparations

    PubMed Central

    Aljuffali, Ibrahim A.; Kalam, Mohd. Abul; Sultana, Yasmin; Imran, Ahamad; Alshamsan, Aws

    2014-01-01

    Quantitative determination of gatifloxacin in tablets, solid lipid nanoparticles (SLNs) and eye-drops using a very simple and rapid chromatographic technique was validated and developed. Formulations were analyzed using a reverse phase SUPELCO® 516 C-18-DB, 50306-U, HPLC column (250 mm × 4.6 mm, 5 ?m) and a mobile phase consisting of disodium hydrogen phosphate buffer:acetonitrile (75:25, v/v) and with orthophosphoric acid pH was adjusted to 3.3 The flow rate was 1.0 mL/min and analyte concentrations were measured using a UV-detector at 293 nm. The analyses were performed at room temperature (25 ± 2 °C). Gatifloxacin was separated in all the formulations within 2.767 min. There were linear calibration curves over a concentration range of 4.0–40 ?g.mL?1 and correlation coefficients of 0.9998 with an average recovery above 99.91%. Detection of analyte from different dosage forms at the same Rt indicates the specificity and stability of the developed method. PMID:25685047

  7. Development and validation of stability-indicating high performance liquid chromatography method to analyze gatifloxacin in bulk drug and pharmaceutical preparations.

    PubMed

    Aljuffali, Ibrahim A; Kalam, Mohd Abul; Sultana, Yasmin; Imran, Ahamad; Alshamsan, Aws

    2015-01-01

    Quantitative determination of gatifloxacin in tablets, solid lipid nanoparticles (SLNs) and eye-drops using a very simple and rapid chromatographic technique was validated and developed. Formulations were analyzed using a reverse phase SUPELCO® 516 C-18-DB, 50306-U, HPLC column (250 mm × 4.6 mm, 5 ?m) and a mobile phase consisting of disodium hydrogen phosphate buffer:acetonitrile (75:25, v/v) and with orthophosphoric acid pH was adjusted to 3.3 The flow rate was 1.0 mL/min and analyte concentrations were measured using a UV-detector at 293 nm. The analyses were performed at room temperature (25 ± 2 °C). Gatifloxacin was separated in all the formulations within 2.767 min. There were linear calibration curves over a concentration range of 4.0-40 ?g.mL(-1) and correlation coefficients of 0.9998 with an average recovery above 99.91%. Detection of analyte from different dosage forms at the same Rt indicates the specificity and stability of the developed method. PMID:25685047

  8. New Salting Out Stability-Indicating and Kinetic Thin Layer Chromatographic Method for Determination of Glimepiride and Metformin HCl Binary Mixture.

    PubMed

    Mohamed, Yahya Abduh Salim; Mohamed, Abdel Maaboud Ismail; Mohamed, Fardous Abdel-Fattah; Ahmed, Sameh Abdel-Raouf

    2015-10-01

    A simple, selective salting out and stability-indicating thin layer chromatographic (SOTLC) technique was developed for determination of two antidiabetic drugs; glimepiride and metformin HCl in pure and in tablets as a binary mixture. Separation was performed on silica gel 60 F254 plates using aqueous ammonium sulfate and acetonitrile (7:3, v/v) as a mobile phase. The Rf values were 0.26 ± 0.02 and 0.73 ± 0.02 for glimepiride and metformin HCl, respectively. The separated bands were scanned at ? 237 nm using CAMAG TLC scanner III. The proposed method focusing on study of all the factors that play important role in the mechanism of salting out process. The proposed method was validated according to ICH guidelines and complied with USP31-NF26 validation guidelines. The correlation coefficients of calibration curves were 0.996 and 0.997 for glimepiride and metformin HCl, respectively, in the concentration range of 60-1,400 ng/band for both drugs. The investigated drugs were also subjected to acidic, basic, oxidative and photo-degradation and kinetic study was carried out. PMID:26006135

  9. Removal of Fecal Indicators, Pathogenic Bacteria, Adenovirus, Cryptosporidium and Giardia (oo)cysts in Waste Stabilization Ponds in Northern and Eastern Australia.

    PubMed

    Sheludchenko, Maxim; Padovan, Anna; Katouli, Mohammad; Stratton, Helen

    2016-01-01

    Maturation ponds are used in rural and regional areas in Australia to remove the microbial loads of sewage wastewater, however, they have not been studied intensively until present. Using a combination of culture-based methods and quantitative real-time PCR, we assessed microbial removal rates in maturation ponds at four waste stabilization ponds (WSP) with (n = 1) and without (n = 3) baffles in rural and remote communities in Australia. Concentrations of total coliforms, E. coli, enterococci, Campylobacter spp., Salmonella spp., F+ RNA coliphage, adenovirus, Cryptosporidium spp. and Giardia (oo) cysts in maturation ponds were measured at the inlet and outlet. Only the baffled pond demonstrated a significant removal of most of the pathogens tested and therefore was subjected to further study by analyzing E. coli and enterococci concentrations at six points along the baffles over five sampling rounds. Using culture-based methods, we found a decrease in the number of E. coli and enterococci from the initial values of 100,000 CFU per 100 mL in the inlet samples to approximately 1000 CFU per 100 mL in the outlet samples for both bacterial groups. Giardia cysts removal was relatively higher than fecal indicators reduction possibly due to sedimentation. PMID:26729150

  10. Novel Validated Stability-Indicating UPLC Method for the Estimation of Naproxen and its Impurities in Bulk Drugs and Pharmaceutical Dosage Form.

    PubMed

    Venkatarao, Papanaboina; Nagendra Kumar, Morrisetty; Ravi Kumar, Maram

    2012-12-01

    A novel, reversed-phase ultra-performance liquid chromatographic method was developed and validated for the determination of related substances in Naproxen (NAP) bulk drugs and dosage forms. The related substances included degradation and process-related impurities. The method was developed using the Waters Acquity BEH C18 column using the gradient program with mobile phase A of a pH 7.0 phosphate buffer and methanol in the ratio of 90: 10 (v/v) and mobile phase B as methanol and acetonitrile in the ratio of 50:50 (v/v). Naproxen and its impurities were monitored at 260 nm. Naproxen was subjected to the stress conditions of oxidative, acid, base, hydrolytic, thermal, humidity, and photolytic degradations. The degradation products were well-resolved from the main peak and its impurities, proving the stability-indicating power of the method. The performance of the method was validated according to the present ICH guidelines for specificity, limit of detection, limit of quantification, linearity, accuracy, precision, ruggedness, and robustness. PMID:23264943

  11. A versatile, stability-indicating and high-throughput ultra-fast liquid chromatography method for the determination of isoflavone aglycones in soybeans, topical formulations, and permeation assays.

    PubMed

    Nemitz, Marina C; Yatsu, Francini K J; Bidone, Juliana; Koester, Letícia S; Bassani, Valquiria L; Garcia, Cássia V; Mendez, Andreas S L; von Poser, Gilsane L; Teixeira, Helder F

    2015-03-01

    There is a growing interest in the pharmaceutical field concerning isoflavones topical delivery systems, especially with regard to their skin care properties and antiherpetic activity. In this context, the present work describes an ultra-fast liquid chromatography method (UFLC) for determining daidzein, glycitein, and genistein in different matrices during the development of topical systems containing isoflavone aglycones (IA) obtained from soybeans. The method showed to be specific, precise, accurate, and linear (0.1 to 5 µg mL(-1)) for IA determination in soybean acid extract, IA-rich fraction obtained after the purification process, IA loaded-nanoemulsions, and topical hydrogel, as well as for permeation/retention assays in porcine skin and porcine esophageal mucosa. The matrix effect was determined for all complex matrices, demonstrating low effect during the analysis. The stability indicating UFLC method was verified by submitting IA to acidic, alkaline, oxidative, and thermal stress conditions, and no interference of degradation products was detected during analysis. Mass spectrometry was performed to show the main compounds produced after acid hydrolysis of soybeans, as well as suggest the main degradation products formed after stress conditions. Besides the IA, hydroxymethylfurfural and ethoxymethylfurfural were produced and identified after acid hydrolysis of the soybean extract and well separated by the UFLC method. The method's robustness was confirmed using the Plackett-Burman experimental design. Therefore, the new method affords fast IA analysis during routine processes, extract purification, products development, and bioanalytical assays. PMID:25618656

  12. Stress Degradation Behavior of Atorvastatin Calcium and Development of a Suitable Stability-Indicating LC Method for the Determination of Atorvastatin, its Related Impurities, and its Degradation Products.

    PubMed

    Vukkum, Pallavi; Moses Babu, J; Muralikrishna, R

    2013-03-01

    A rapid, reversed-phase liquid chromatographic method was developed for the quantitative determination of Atorvastatin calcium, its related substances (12 impurities), and degradation impurities in bulk drugs. The chromatographic separation was achieved on a Zorbax Bonus-RP column by employing a gradient elution with water-acetonitrile-trifluoroacetic acid as the mobile phase in a shorter run time of 25 min. The flow rate was 1.0 mL/min and the detection wavelength was 245 nm. The drug substance was subjected to stress studies such as hydrolysis, oxidation, photolysis, and thermal degradation, and considerable degradation was observed in acidic hydrolysis, oxidative, thermal, and photolytic stress conditions. The formed degradation products were reported and were well-resolved from the Atorvastatin and its related substances. The stressed samples were quantified against a qualified reference standard and the mass balance was found to be close to 99.5% (w/w) when the response of the degradant was considered to be equal to the analyte (i.e. Atorvastatin), which demonstrates the stability-indicating capability of the method. The method was validated in agreement with ICH requirements. The method developed here was single and shorter (25 min method for the determination of all 12 related impurities of Atorvastatin and its degradation products), with clearly better resolution and higher sensitivity than the European (85 min method for the determination of six impurities) and United States pharmacopeia (115 min and 55 min, two different methods for the determination of six related substances). PMID:23641331

  13. Development of validated stability-indicating chromatographic method for the determination of fexofenadine hydrochloride and its related impurities in pharmaceutical tablets

    PubMed Central

    2011-01-01

    A simple reversed phase high performance liquid chromatographic method with diode array detector (HPLC-DAD) has been developed and subsequently validated for the determination of fexofenadine hydrochloride (FEX) and its related compounds; keto fexofenadine (Impurity A), meta isomer of fexofenadine (Impurity B), methyl ester of fexofenadine (Impurity C) in addition to the methyl ester of ketofexofenadine (Impurity D). The separation was based on the use of a Hypersil BDS C-18 analytical column (250 × 4.6 mm, i.d., 5 ?m). The mobile phase consisted of a mixture of phosphate buffer containing 0.1 gm% of 1-octane sulphonic acid sodium salt monohydrate and 1% (v/v) of triethylamine, pH 2.7 and methanol (60:40, v/v). The separation was carried out at ambient temperature with a flow rate of 1.5 ml/min. Quantitation was achieved with UV detection at 215 nm using lisinopril as internal standard, with linear calibration curves at concentration ranges 0.1-50 ?g/ml for FEX and its related compounds. The optimized conditions were used to develop a stability-indicating HPLC-DAD method for the quantitative determination of FEX and its related compounds in tablet dosage forms. The drugs were subjected to oxidation, hydrolysis, photolysis and heat to apply stress conditions. Complete separation was achieved for the parent compounds and all degradation products. The method was validated according to ICH guidelines in terms of accuracy, precision, robustness, limits of detection and quantitation and other aspects of analytical validation. PMID:22136482

  14. Gradient HPLC-diode array detector stability-indicating determination of lidocaine hydrochloride and cetylpyridinium chloride in two combined oral gel dosage forms.

    PubMed

    Belal, Tarek S; Shaalan, Rasha A; Haggag, Rim S

    2011-01-01

    A simple, rapid, and selective HPLC-diode array detector method was developed for the simultaneous determination of lidocaine hydrochloride (LD) and cetylpyridinium chloride (CPC) in two combined pharmaceutical formulations. Effective chromatographic separation was achieved on a Zorbax SB-C8 (4.6 x 250 mm, 5 microm particle size) column with gradient elution using a mobile phase composed of 0.05 M phosphoric acid and acetonitrile. The gradient elution started with 25% (v/v) acetonitrile, ramped up linearly to 85% in 5 min, and then was constant until the end of the run. The mobile phase was pumped at a flow rate of 1.2 mL/min. The multiple wavelength detector was set at 214 and 258 nm, and quantification of the analytes was based on measuring their peak areas. The retention times for LD and CPC were about 3.4 and 7.3 min, respectively. The reliability and analytical performance of the proposed HPLC procedure were statistically validated with respect to linearity, range, precision, accuracy, selectivity, robustness, LOD, and LOQ. Calibration curves were linear in the range of 5-200 and 10-400 microg/mL for LD and CPC, respectively, with correlation coefficients > 0.999. The proposed method was proven to be stability-indicating by the resolution of the two analytes from the related substance and potential impurity (2,6-dimethylaniline) as well as from forced-degradation products. The validated HPLC method was extended to the analysis of LD and CPC in two combined oral gel preparations for which the two analytes were successfully resolved from the pharmaceutical adjuvants and quantified with recoveries not less than 97.9%. PMID:21563684

  15. Internet Addiction: Stability and Change

    ERIC Educational Resources Information Center

    Huang, Chiungjung

    2010-01-01

    This longitudinal study examined five indices of stability and change in Internet addiction: structural stability, mean-level stability, differential stability, individual-level stability, and ipsative stability. The study sample was 351 undergraduate students from end of freshman year to end of junior year. Convergent findings revealed stability

  16. The importance of aeration mode and flowrate in the determination of the biological activity and stability of organic wastes by respiration indices.

    PubMed

    Almeira, Natividad; Komilis, Dimitrios; Barrena, Raquel; Gea, Teresa; Sánchez, Antoni

    2015-11-01

    The aim of this study was to assess the effect of different air flowrates and different aeration modes on the respiration activity of three organic substrates of different stability degree: (i) a constant flowrate and (ii) a continuously adjusted air flowrate that optimized the oxygen uptake rate (OUR). Above 20L air kg(-1)DMh(-1), at the constant flow regime, the resulting dynamic respiration index at 24h (DRI24) and the cumulative respiration at four days (AT4) were statistically similar. At the OUR based aeration regime, the DRI24 and AT4 were statistically similar at all initial flowrates tested. Above a minimum threshold, cumulative air flow of around 3000Lairkg(-1) DM during a 5day period, the respiration activity was similar, particularly for the two less active substrates. This study highlights the importance of selecting the aeration to obtain reliable measures of biological activity and stability in organic wastes. PMID:26253909

  17. Complexity in Estimation of Esomeprazole and its Related Impurities’ Stability in Various Stress Conditions in Low-Dose Aspirin and Esomeprazole Magnesium Capsules

    PubMed Central

    Reddy, Palavai Sripal; Hotha, Kishore Kumar; Sait, Shakil

    2013-01-01

    A complex, sensitive, and precise high-performance liquid chromatographic method for the profiling of impurities of esomeprazole in low-dose aspirin and esomeprazole capsules has been developed, validated, and used for the determination of impurities in pharmaceutical products. Esomeprazole and its related impurities’ development in the presence of aspirin was traditionally difficult due to aspirin’s sensitivity to basic conditions and esomeprazole’s sensitivity to acidic conditions. When aspirin is under basic, humid, and extreme temperature conditions, it produces salicylic acid and acetic acid moieties. These two byproducts create an acidic environment for the esomeprazole. Due to the volatility and migration phenomenon of the produced acetic acid and salicylic acid from aspirin in the capsule dosage form, esomeprazole’s purity, stability, and quantification are affected. The objective of the present research work was to develop a gradient reversed-phase liquid chromatographic method to separate all the degradation products and process-related impurities from the main peak. The impurities were well-separated on a RP8 column (150 mm × 4.6mm, X-terra, RP8, 3.5?m) by the gradient program using a glycine buffer (0.08 M, pH adjusted to 9.0 with 50% NaOH), acetonitrile, and methanol at a flow rate of 1.0 mL min?1 with detection wavelength at 305 nm and column temperature at 30°C. The developed method was found to be specific, precise, linear, accurate, rugged, and robust. LOQ values for all of the known impurities were below reporting thresholds. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis, and thermal degradation in the presence of aspirin. The developed RP-HPLC method was validated according to the present ICH guidelines for specificity, linearity, accuracy, precision, limit of detection, limit of quantification, ruggedness, and robustness. PMID:23833714

  18. Capability measurement of size-exclusion chromatography with a light-scattering detection method in a stability study of bevacizumab using the process capability indices.

    PubMed

    Oliva, Alexis; Llabrés, Matías; Fariña, José B

    2014-08-01

    In this study, we investigated if the size-exclusion chromatography coupled with light-scattering and refractive index detection (SEC/LS/RI) method is fitted for its intended purpose and checked if the analytical method is able to provide enough conforming results. For this, the process capability indices Cp, Cpk, and Cpm were computed. The traditional X-chart and moving range (MR) chart were used by the same analyst to monitor the equipment in the laboratory over a 1-year period. For this, a bovine serum albumin (BSA) sample (0.3 mg mL(-1)) with a nominal Mw of 66.4 kDa was analyzed each working day. The results confirmed that the analytical method is in-control and stable. To determine whether the given process meets the present capability requirement and runs under the desired quality conditions, the Pearn and Shu (2003) method based on the lower confidence bound C on Cpm was used. The estimator Cpm was 1.81, and the lower confidence bound C was 1.40. We therefore conclude that the true value of the method capability Cpm is no less than 1.40 with a 95% level of confidence. This result indicates that the method is satisfactory and no stringent precision control is required. The usefulness of this method was applied in the characterization of bevacizumab commercial pharmaceutical preparations stored under different conditions that lead to aggregation. In this case, the computed Cpm index was 0.98 (0.70, 1.26), which indicates that the method does not comply with the specification limits and needs to be revised. The quality improvement effort should: (1) reduce the uncertainty in the absolute Mw determination; (2) either move the process mean closer to the target value or reduce the process variation, i.e. improve the method accuracy (?-T) and precision (?(2)). On this point, the Bayesian posterior distribution of the mean and standard deviation pointed out the need to control the precision but specially accuracy in order to reduce the overall uncertainty of analytical method and thus, the method is capable. PMID:24786652

  19. The "Golden Shale": An indicator of coastal stability for Marble Point, McMurdo Sound, over the last four million years

    USGS Publications Warehouse

    Claridge, G.G.C.; Campbell, I.B.

    2007-01-01

    A small sedimentary deposit near Gneiss Point on the western side of McMurdo Sound, previously identified as shale, is described. The deposit is phillipsite, a zeolite that is believed to have formed from the deposition and alteration of volcanic ash in a small ice-marginal saline lake. Other previously recorded occurrences of phillipsite in the dry valleys are believed to be several million years old. A similar age for this deposit is suggested for the Gneiss Point deposit. This is consistent with other weathering and landscape features found in the immediate area, including traces of halloysite in soils. The deposit is very close to sea level but could not have formed if the site had been below sea level, indicating that there has been very little uplift following that which caused the sea to retreat from the Wright Fiord.

  20. Impurity profiling and a stability-indicating UPLC method development and validation for the estimation of related impurities of halobetasol propionate in halobetasol propionate 0.05% (w/w) cream.

    PubMed

    Prakash, Lakkireddy; Malipeddi, H; Subbaiah, B Venkata; Lakka, Narasimha S

    2015-01-01

    A simple, short and stability-indicating reverse phase-ultra-performance liquid chromatography method was developed and validated for the quantitative determination of related impurities of halobetasol propionate in halobetasol propionate 0.05% cream formulation. The proposed method was developed on an ACQUITY UPLC™ BEH Phenyl (2.1 × 100 mm, 1.7 µm) column at 40°C with a mobile phase containing a gradient mixture of potassium hydrogen phosphate buffer and acetonitrile and methanol as modifiers with a runtime of 13.0 min at a monitored wavelength of 242 nm. A simple preparative method and liquid chromatography-mass spectrometry-compatible UPLC method also were developed for the isolation and identification of impurities and degradation products. The drug was subjected to forced-degradation conditions and found to degrade significantly. The stability-indicating capability of the developed method is established by analyzing forced-degradation samples in which the spectral purity of halobetasol propionate is ascertained along with the separation of degradation products from the analyte peak. The developed method was validated as per International Conference on Harmonization guidelines. The developed method is precise (%relative standard deviation <2.0) and is capable of detecting and quantifying all the six impurities at a level of 0.01 and 0.03%, respectively, with respect to test concentration. The wide linearity range, sensitivity, accuracy, short retention time and simple mobile phase imply that the method is suitable for routine quantification of halobetasol propionate and its related substances. PMID:24795078

  1. Planktonic Foram Sr/Ca Indicates Long-Term Stability of Carbonate Saturation State and Seawater Sr/Ca during the Cenozoic

    NASA Astrophysics Data System (ADS)

    Caves, J. K.; Opdyke, B.; Owens, R.

    2012-12-01

    Changes in ocean chemistry are poorly understood over timescales of tens of millions of years; yet, such changes reflect the interplay of fundamental Earth processes, such as the long-term carbon-cycle, evolution, tectonics, and weathering. Simultaneously constraining two ocean chemical parameters could help deconvolve these processes and improve our understanding of the marine response to anthropogenic perturbations to the carbon cycle. We use a multi-proxy and modeling approach, utilizing planktonic foram Sr/Ca, calcite cements, and box-modeling to produce a first-attempt at a Cenozoic carbonate saturation state (?) curve and to improve estimates of long-term seawater Sr/Ca variability. Evidence from both culturing studies and glacial-interglacial records indicate that foram Sr/Ca is dominantly sensitive to ?, suggesting that foram Sr/Ca can be used to reconstruct ? if seawater Sr/Ca can be constrained. We apply this new proxy to an updated Cenozoic planktonic foram Sr/Ca record, comprising 1680 records from 18 publications. Our foram Sr/Ca record is largely constant during the Cenozoic, with a minimum at the Miocene-Pliocene boundary and a pronounced shift at 38Mya, corresponding to a major planktonic foram overturning event, which we interpret as a species offset. To constrain seawater Sr/Ca, we use both trace element data from calcite cements and a box-model linked to the 87Sr/86Sr record. Both the model and calcite cement data suggest seawater Sr/Ca has remained relatively stable, with slightly higher values during the Paleogene, a minimum during the mid-Miocene, and variability driven by changes in carbonate deposition and mineralogy. Relative to calcite, ? was low (~4) during much of the Paleogene, but increased during the Oligocene, reaching a maximum during the mid-Miocene. ? declined to a local minimum at the Miocene-Pliocene boundary, and has since increased to pre-industrial values of 5-6. This record helps explain the lag between the aragonite-calcite transition in the early Paleogene and the widespread appearance of scleractinian reefs during the Oligocene, suggesting that aragonitic reefs are particularly sensitive to ?. Further, the combination of trace element proxies from forams and calcite cements and modeling suggest that ? and seawater Sr/Ca have remained relatively constant during the Cenozoic.

  2. ECOLOGICAL INDICATORS

    EPA Science Inventory

    An international symposium on ecological indicators was developed to explore both the potential of ecological indicators and the issues surrounding their development and implementation. his symposium presented state-of-the-science information on the identification, application re...

  3. Development of RP UPLC-TOF/MS, stability indicating method for omeprazole and its related substances by applying two level factorial design; and identification and synthesis of non-pharmacopoeial impurities.

    PubMed

    Jadhav, Sushant Bhimrao; Kumar, C Kiran; Bandichhor, Rakeshwar; Bhosale, P N

    2016-01-25

    A new UPLC-TOF/MS compatible, reverse phase-stability indicating method was developed for determination of Omeprazole (OMP) and its related substances in pharmaceutical dosage forms by implementing Design of Experiment (DoE) i.e. two level full factorial Design (2(3)+3 center points=11 experiments) to understand the Critical Method Parameters (CMP) and its relation with Critical Method Attribute (CMA); to ensure robustness of the method. The separation of eleven specified impurities including conversion product of OMP related compound F (13) and G (14) i.e. Impurity-I (1), OMP related compound-I (11) and OMP 4-chloro analog (12) was achieved in a single method on Acquity BEH shield RP18 100×2.1mm, 1.7?m column, with inlet filter (0.2?m) using gradient elution and detector wavelength at 305nm and validated in accordance with ICH guidelines and found to be accurate, precise, reproducible, robust and specific. The drug was found to degrade extensively in heat, humidity and acidic conditions and forms unknown degradation products during stability studies. The same method was used for LC-MS analysis to identify m/z and fragmentation of maximum unknown impurities (Non-Pharmacopoeial) i.e. Impurity-I (1), Impurity-III (3), Impurity-V (5) and Impurity-VIII (9) formed during stability studies. Based on the results, degradation pathway for the drug has been proposed and synthesis of identified impurities i.e. impurities (Impurity-I (1), Impurity-III (3), Impurity-V (5) and Impurity-VIII (9)) are discussed in detail to ensure in-depth understanding of OMP and its related impurities and optimum performance during lifetime of the product. PMID:26600119

  4. ESI-MS and MS/MS identification of the first ceramide analogues of fumonisin B? mycotoxin from a Fusarium verticillioides culture following RP-HPLC separation.

    PubMed

    Bartók, T; Szécsi, Á; Juhász, K; Bartók, M; Mesterházy, Á

    2013-01-01

    Following the earlier detection of six new esterified fumonisin B? (EFB?) isomers containing three acyl groups in a Fusarium verticillioides-inoculated rice culture, it was assumed that linoleic, palmitic or oleic acid esterifies one of the free OH groups on the fumonisin backbone. On the basis of the results of our recent investigations we now propose that these EFB? isomers are actually 3-O- and 5-O-acyl derivatives of FB? (3-O-linoleoyl-FB?, 5-O-linoleoyl-FB?, 3-O-palmitoyl-FB?, 5-O-palmitoyl-FB?, 3-O-oleoyl-FB? and 5-O-oleoyl-FB?). A F. verticillioides strain was identified that produced not only O-acyl-FB? isomers, but also low amounts of three N-acyl derivatives (N-linoleoyl-FB?, N-palmitoyl-FB? and N-oleoyl-FB?), which eluted from the HPLC column after the six O-acyl compounds and in the same sequence as for the O-acyl compounds. The characteristic positive and negative ESI-MS/MS spectra obtained after solid-phase extraction of the culture extract facilitated identification of these N-acyl-FB? derivatives. The biosynthesis of N-palmitoyl-FB? by F. verticillioides was verified by spiking the culture extract with synthetic N-palmitoyl-FB?. This is the first report of the separation and mass spectrometric identification of the six O-acyl- and three N-acyl-FB? derivatives extracted from a F. verticillioides culture. PMID:23837460

  5. Simultaneous quantitative determination of six active components in traditional Chinese medicinal preparation Cerebralcare Granule® by RP-HPLC coupled with diode array detection for quality control.

    PubMed

    Wang, Xiang-yang; Ma, Xiao-hui; Li, Wei; Chu, Yang; Guo, Jia-hua; Zhou, Shui-ping; Zhu, Yong-hong

    2014-09-01

    A simple, accurate and reliable method for the simultaneous separation and determination of six active components (protocatechuic acid, chlorogenic acid, caffeic acid, paeoniflorin, ferulic acid and rosmarinic acid) in traditional Chinese medicinal preparation Cerebralcare Granule(®) (CG) was developed using reverse-phase high-performance liquid chromatography coupled with diode array detector detection. The chromatographic separation was performed on a Hypersil GOLD C18 column with aqueous formic acid (0.1%, v/v) and acetonitrile as mobile phase at a flow rate of 0.2 ml/min at 30 °C. Because of the different UV characteristics of these components, change detection wavelength method was used for quantitative analysis. All of the analytes showed good linearity (r > 0.9992). The established method showed good precision and relative standard deviations (%) for intra-day and inter-day variations of 0.15-1.81 and 0.11-1.98%, respectively. The validated method was successfully applied to the simultaneously determination of six active components in CG from different batches. PMID:23934038

  6. Determination of pKa values of nonsteroidal antiinflammatory drug-oxicams by RP-HPLC and their analysis in pharmaceutical dosage forms.

    PubMed

    Demiralay, Ebru Cubuk; Alsancak, Guleren; Ozkan, Sibel A

    2009-09-01

    In this study, pK(a) values were determined by using the dependence of the capacity factor on the pH of the mobile phase for four ionizable substances, namely, tenoxicam, piroxicam, meloxicam, and naproxen (I.S.). The effect of the mobile phase composition on the ionization constant was studied by measuring the pK(a) at different ACN concentrations, ranging from 30 to 40%. The adequate condition for the chromatographic determination of these compounds in pharmaceutical dosage forms was established based on the different retention behaviors of the species. An octadecylsilica Nucleosil C18 column (150 x 4.6 mm, 5 microm) was used for all the determinations. The chromatographic separation of oxicams was carried out using acetonitrile (ACN)/water at 35% v/v, containing 65 mM phosphoric acid and UV detection at a wavelength of 355 nm. The method developed was successfully applied to the simultaneous determination of these drug compounds in laboratory-prepared mixtures and their commercial pharmaceutical dosage forms. Each analysis requires no longer than 12 min. PMID:19662642

  7. Development and validation of RP-HPLC and ultraviolet spectrophotometric methods of analysis for the quantitative estimation of antiretroviral drugs in pharmaceutical dosage forms.

    PubMed

    Sarkar, Mahua; Khandavilli, Sateesh; Panchagnula, Ramesh

    2006-01-18

    A high-performance liquid chromatographic and an UV spectrophotometric method were developed and validated for the quantitative determination of three antiretroviral drugs viz. Lamivudine, Stavudine and Nevirapine that constitute one of the first line regimens in antiretroviral therapy. The different analytical performance parameters such as linearity, precision, accuracy, specificity, limit of detection (LOD) and limit of quantification (LOQ) were determined according to International Conference on Harmonization ICH Q2B guidelines. Chromatography was carried out by isocratic technique on a reversed-phase C-18 SYMMETRY column with mobile phase based and optimized depending on the polarity of the molecules. The UV spectrophotometric determinations were performed at 270, 265 and 313 nm for Lamivudine, Stavudine and Nevirapine, respectively. The linearity of the calibration curves for each analyte in the desired concentration range is good (r(2)>0.999) by both the HPLC and UV methods. Both the methods were accurate and precise with recoveries in the range of 97 and 103% for all the three drugs and relative standard deviation (R.S.D.) <5%. Moreover, the accuracy and precision obtained with HPLC correlated well with the UV method which implied that UV spectroscopy can be a cheap, reliable and less time consuming alternative for chromatographic analysis. The proposed methods are highly sensitive, precise and accurate and hence were successfully applied for the reliable quantification of API content in the commercial formulations of Lamivudine, Stavudine and Nevirapine. PMID:16330261

  8. Development and validation of an RP-HPLC method for the quantitation of odanacatib in rat and human plasma and its application to a pharmacokinetic study.

    PubMed

    Police, Anitha; Gurav, Sandip; Dhiman, Vinay; Zainuddin, Mohd; Bhamidipati, Ravi Kanth; Rajagopal, Sriram; Mullangi, Ramesh

    2015-11-01

    A simple, specific, sensitive and reproducible high-performance liquid chromatography (HPLC) assay method has been developed and validated for the estimation of odanacatib in rat and human plasma. The bioanalytical procedure involves extraction of odanacatib and itraconazole (internal standard, IS) from a 200 ?L plasma aliquot with simple liquid-liquid extraction process. Chromatographic separation was achieved on a Symmetry Shield RP18 using an isocratic mobile phase at a flow rate of 0.7 mL/min. The UV detection wave length was 268 nm. Odanacatib and IS eluted at 5.5 and 8.6 min, respectively with a total run time of 10 min. Method validation was performed as per US Food and Drug Administration guidelines and the results met the acceptance criteria. The calibration curve was linear over a concentration range of 50.9-2037 ng/mL (r(2) = 0.994). The intra- and inter-day precisions were in the range of 2.06-5.11 and 5.84-13.1%, respectively, in rat plasma and 2.38-7.90 and 6.39-10.2%, respectively, in human plasma. The validated HPLC method was successfully applied to a pharmacokinetic study in rats. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25914381

  9. Development and validation of RP-HPLC method for simultaneous estimation of nimesulide, phenylephrine hydrochloride, chlorpheniramine maleate and caffeine anhydrous in pharmaceutical dosage form.

    PubMed

    Kumar, Ashok; Sharma, Rishbha; Nair, Anroop; Saini, Gautam

    2012-01-01

    In this study, a simple, specific and accurate reverse phase high performance liquid chromatographic method was developed for the simultaneous determination of nimesulide (NS), phenylephrine hydrochloride (PE), chlorpheniramine maleate (CPM) and caffeine anhydrous (CF) in pharmaceutical dosage forms. A reversed phase Hypersil phenyl column (4.6 mm x 25 cm) with mobile phase having pH 5.5 consisting of methanol and buffer (55:45, v/v) was used. The flow rate was 1.0 mL per minute and the effluents were monitored at 214 nm. The retention times of all the drugs were found to be 7.47 min (NS), 3.944 min (PE), 4.55 min (CF) and 17.15 min (CPM), respectively. The linearity for all the drugs was obtained in the range of 300-800 microg/mL (NS), 15-32 microg/mL (PE), 16-32 microg/mL (CPM) and 30-180 microg/mL (CF), respectively. The results of analysis have been well validated according to guidelines of International Conference of Harmonisation of technical requirements for registration of pharmaceuticals for human use. The method was found to be simple, precise, economical, less time consuming and reproducible. Hence, the suggested procedure could be used for the determination of all the four drugs in commercial preparations. PMID:23285660

  10. RP-HPLC method using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate incorporated with normalization technique in principal component analysis to differentiate the bovine, porcine and fish gelatins.

    PubMed

    Azilawati, M I; Hashim, D M; Jamilah, B; Amin, I

    2015-04-01

    The amino acid compositions of bovine, porcine and fish gelatin were determined by amino acid analysis using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate as derivatization reagent. Sixteen amino acids were identified with similar spectral chromatograms. Data pre-treatment via centering and transformation of data by normalization were performed to provide data that are more suitable for analysis and easier to be interpreted. Principal component analysis (PCA) transformed the original data matrix into a number of principal components (PCs). Three principal components (PCs) described 96.5% of the total variance, and 2 PCs (91%) explained the highest variances. The PCA model demonstrated the relationships among amino acids in the correlation loadings plot to the group of gelatins in the scores plot. Fish gelatin was correlated to threonine, serine and methionine on the positive side of PC1; bovine gelatin was correlated to the non-polar side chains amino acids that were proline, hydroxyproline, leucine, isoleucine and valine on the negative side of PC1 and porcine gelatin was correlated to the polar side chains amino acids that were aspartate, glutamic acid, lysine and tyrosine on the negative side of PC2. Verification on the database using 12 samples from commercial products gelatin-based had confirmed the grouping patterns and the variables correlations. Therefore, this quantitative method is very useful as a screening method to determine gelatin from various sources. PMID:25442566

  11. Standardization of RP-HPLC methods for the detection of the major peanut allergens Ara h 1, Ara h 2 and Ara h 3.

    PubMed

    Singh, Harmit; Cantoria, Mary Jo; Malave, Poonam; Saputra, Denny; Maleki, Soheila

    2016-03-01

    Crude peanut extract (CPE) was analyzed for three major allergens (Ara h 1, h 2, and h 3) using a C12 and a C18 column at two wavelengths (280 and 220nm) and under different solvent conditions. HPLC profiles were compared for retention time, resolution, and peak heights. CPE samples were spiked with pure allergens to identify the peaks corresponding to allergens. The HPLC fractions of corresponding allergens were collected and freeze-dried in order to perform SDS-PAGE and immunoblotting tests. The best method was identified the one with a shorter retention time, better resolution, and greater peak height as compared with the other methods. In general, the peak heights were greater at 220nm than at 280nm. The major disadvantage of the C12 column was the need for two sets of conditions to identify the allergens as compared to the C18 column where all three allergens could be identified in one run. PMID:26471570

  12. Identification of lipopeptide isoforms by MALDI-TOF-MS/MS based on the simultaneous purification of iturin, fengycin, and surfactin by RP-HPLC.

    PubMed

    Yang, Huan; Li, Xu; Li, Xue; Yu, Huimin; Shen, Zhongyao

    2015-03-01

    A three-stage linear gradient strategy using reverse-phase high-performance liquid chromatography (HPLC) was optimized for rapid, high-quality, and simultaneous purification of the lipopeptide isoforms of iturin, fengycin, and surfactin, which may differ in composition by only a single amino acid and/or the fatty acid residue. Matrix-assisted laser desorption ionization time-of-flight tandem mass spectrometry (MALDI-TOF-MS/MS) was applied to detect the lipopeptides harvested from each reversed-phase HPLC peak. Amino acid analysis based on phenyl isothiocyanate derivatization was further used for confirmation of the amino acid species and molar ratio in a certain HPLC fraction. By this MALDI-TOF-MS/MS coupled with amino acid analysis, it was revealed that iturin at m/z 1,043 consists of a circular Asn-Tyr-Asn-Gln-Pro-Asn-Ser peptide and C14 ?-OH fatty acid. Surfactin homologs from Bacillus subtilis THY-7 at m/z 1,030, 1,044, 1,058, and 1,072 possess a circular Glu-Leu-Leu-Val-Asp-Leu-Leu peptide and the ?-OH fatty acid with a different length (C13-C16). Fengycin species at m/z 1,463 and 1,477 are homologs possessing the circular peptide Glu-Orn-Tyr-Thr-Glu-Ala-Pro-Gln-Tyr-Ile linked to a C16 or C17 ?-OH fatty acid, whereas fengycin at m/z 1,505 contains a Glu-Orn-Tyr-Thr-Glu-Val-Pro-Gln-Tyr-Ile sequence with a Val instead of Ala at position 6. The method developed in this work provided an efficient approach for characterization of diverse lipopeptide isoforms from the iturin, fengycin, and surfactin families. PMID:25662934

  13. Development of a stability-indicating LC method for determination of a synthetic chalcone derivative in a nanoemulsion dosage form and identification of the main photodegradation product by LC-MS.

    PubMed

    Mattos, Cristiane B; Deponti, Vânia B; Barreto, Fabiano; Simões, Cláudia M O; Andrighetti-Frohner, Carla R; Nunes, Ricardo J; Steindel, Mário; Teixeira, Helder F; Koester, Letícia S

    2012-11-01

    This study aimed to develop and validate a stability indicating LC for the determination of 5-(2-benzoylethenyl)-N-benzyl-2 methoxybenzenesulfonamide (SCD - a synthetic chalcone derivative), and evaluate the degradation profile of the compound under different stress conditions recommended by International Conference on Harmonization (ICH). Chromatographic separation was performed on a silica C18 column, methanol-water mobile phase 70:30 (v:v), pH 5.0 adjusted with the addition of trifluoroacetic acid (TFA) at a flow rate of 1.0 mL min(-1); detection by UV absorption at 330 nm. The method was validated for linearity, precision, accuracy, robustness and specificity. The SCD was subjected to forced degradation and peak photodegradation product was well separated from the pure substance, with retention times significantly different, indicating the specificity of the method. Second-order degradation kinetics of SCD was observed under photodegradation and base-induced degradation. In order to identify the product formed under photodegradation, liquid chromatography-tandem mass spectrometry (LC-MS/MS) was performed. These results indicate that the method can be successfully used in order to assay SCD in a nanoemulsion dosage form, and that this formulation has a protective effect over SCD degradation. PMID:22884784

  14. Indices To Measure Stability of Rule Application.

    ERIC Educational Resources Information Center

    Tatsuoka, Kikumi K.

    When learning is taking place, students test their hypotheses and evaluate them, and modify their current theories on the basis of new information. This phenomenon is known as "hypothesis testing view" or "theory changes." Many students change their rules to another while they are taking a test. This study introduced a new concept called "slip…

  15. Community indicators

    PubMed Central

    Flynn, Andrea; Wells, Samantha

    2014-01-01

    Community indicators are used to assess the impact of alcohol on communities. This article reviews the main data sources for community indicators, discusses their strengths and limitations, and discusses indicators used in reference to four main topics relating to alcohol use and problems at the community level: alcohol use, patterns, and problems; alcohol availability; alcohol-related health outcomes/trauma; and alcohol-related crime and enforcement. It also reviews the challenges associated with collecting community indicator data, along with important innovations in the field that have contributed to better knowledge of how to collect and analyze community-level data on the impact of alcohol. PMID:24881322

  16. RBC indices

    MedlinePLUS

    ... hemoglobin concentration (MCHC); Mean corpuscular volume (MCV); Red blood cell indices ... hemoglobin. The MCV reflects the size of red blood cells. The MCH and MCHC reflect the hemoglobin content ...

  17. Position indicator

    DOEpatents

    Tanner, David E. (Poway, CA)

    1981-01-01

    A nuclear reactor system is described in which a position indicator is provided for detecting and indicating the position of a movable element inside a pressure vessel. The movable element may be a valve element or similar device which moves about an axis. Light from a light source is transmitted from a source outside the pressure vessel to a first region inside the pressure vessel in alignment with the axis of the movable element. The light is redirected by a reflector prism to a second region displaced radially from the first region. The reflector prism moves in response to movement of the movable element about its axis such that the second region moves arcuately with respect to the first region. Sensors are arrayed in an arc corresponding to the arc of movement of the second region and signals are transmitted from the sensors to the exterior of the reactor vessel to provide indication of the position of the movable element.

  18. 46 CFR 178.210 - Stability information.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Stability information. 178.210 Section 178.210 Shipping... information. (a) Stability information (stability details indicated on the Certificate of Inspection, a... this section. Enough stability information, including stability calculations and assumptions made...

  19. 46 CFR 178.210 - Stability information.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Stability information. 178.210 Section 178.210 Shipping... information. (a) Stability information (stability details indicated on the Certificate of Inspection, a... this section. Enough stability information, including stability calculations and assumptions made...

  20. 46 CFR 178.210 - Stability information.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Stability information. 178.210 Section 178.210 Shipping... information. (a) Stability information (stability details indicated on the Certificate of Inspection, a... section. Enough stability information, including stability calculations and assumptions made to use...

  1. Geology and slope stability in selected parts of The Geysers geothermal resources area: a guide to geologic features indicative of stable and unstable terrain in areas underlain by Franciscan and related rocks

    SciTech Connect

    Bedrossian, T.L.

    1980-01-01

    The results of a 4-month study of various geologic and topographic features related to the stability of Franciscan terrain in The Geysers GRA are presented. The study consisted of investigations of geologic and topographic features, throughout The Geysers GRA, and geologic mapping at a scale of 1:12,000 of approximately 1500 acres (600 hectares) of landslide terrain within the canyon of Big Sulphur Creek in the vicinity of the Buckeye mine (see plate 1). The area mapped during this study was selected because: (1) it is an area of potential future geothermal development, and (2) it illustrates that large areas mapped as landslides on regional scales (McLaughlin, 1974, 1975b; McNitt, 1968a) may contain zones of varying slope stability and, therefore, should be mapped in more detail prior to development of the land.

  2. Mass Spectrometric Identification of the Arginine and Lysine deficient Proline Rich Glutamine Rich Wheat Storage Proteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tandem mass spectrometry (MS/MS) of enzymatic digest has made possible identification of a wide variety of proteins and complex samples prepared by such techniques as RP-HPLC or 2-D gel electrophoresis. Success requires peptide fragmentation to be indicative of the peptide amino acid sequence. The f...

  3. Stabilization of supersaturated zincate solutions

    SciTech Connect

    Dmitrenko, V.E.; Zubov, M.S.; Baulov, V.I.; Balyakina, N.N.; Kotov, A.V.

    1986-09-10

    This paper investigates the stabilization of supersaturated zincate electrolytes in a silver-zinc battery by the addition of potassium hydroxide, lithium hydroxide, and molasses. Molasses, in combination with the hydroxide additives, was found to demonstrate a profound stabilizing influence on the zincate supersaturation and the electrolyte. Preliminary data on discharge of a battery using the combined additive indicates that it has higher discharge capacity than do batteries which contain the individual additives. The chemistry of this stabilizing influence is discussed.

  4. Monitoring cheddar cheese ripening by chemical indices of proteolysis. 3. Identification of several high-molecular mass peptides.

    PubMed

    Belitz, H D; Kaiser, K P

    1993-08-01

    Two Cheddar cheeses from two different production plants were ripened over 24 weeks at 10 degrees C and then analysed for peptides soluble in citrate buffer at pH 4.6 by reversed-phase (RP)-HPLC. Thirteen peptides with a chain length of between 35 and 65 amino acid residues and molecular masses between 3800 and 7400 were isolated and assigned to the corresponding amino acid sequences of the casein fractions via Edman degradation and amino acid composition. All peptides were fragments of the region K29-S96 of beta-casein A1 and A2, and eleven of them had M93 as the C-terminal. The amounts and proportions of these peptides varied differently during ripening of the two cheeses, so they may be suitable markers for characterizing the stage of ripening. PMID:8212903

  5. Thermal indicator for wells

    DOEpatents

    Gaven, Jr., Joseph V. (Oakton, VA); Bak, Chan S. (Newbury Park, CA)

    1983-01-01

    Minute durable plate-like thermal indicators are employed for precision measuring static and dynamic temperatures of well drilling fluids. The indicators are small enough and sufficiently durable to be circulated in the well with drilling fluids during the drilling operation. The indicators include a heat resistant indicating layer, a coacting meltable solid component and a retainer body which serves to unitize each indicator and which may carry permanent indicator identifying indicia. The indicators are recovered from the drilling fluid at ground level by known techniques.

  6. Phytotoxicity as an indicator of stability of broiler production residues.

    PubMed

    Mendes, P M; Becker, R; Corrêa, L B; Bianchi, I; Dai Prá, M A; Lucia, T; Corrêa, E K

    2016-02-01

    Beddings used for successive broiler lots act as substrate to absorb water and feed from the excreta and may be subsequently used as agricultural fertilizers. This study evaluated the physicochemical characteristics and the phytotoxicity of beddings used to raise five consecutive broiler lots in five aviaries. Samples were collected for beddings not used yet and for beddings used at each of the five broiler lots. Lettuce and cucumber seeds were considered as phytotoxicity bioindicators. As beddings were used for greater number of lots, N, Ca, K, Mg and P contents generally increased, but the C content decreased, the pH alkalinized and humidity was reduced (P < 0.05). The germination index for lettuce and cucumber seeds was reduced with increased bedding (P < 0.05). Beddings used for at least five broiler lots presented decreased C:N ratio and would not recommended for agricultural use due to its toxicity for both tested seeds. PMID:26686067

  7. Stabilizing population.

    PubMed

    Brown, L; Mitchell, J

    1998-04-01

    This article is a reprint of the Worldwatch Institute's "State of the World Report," Chapter 10: "Building a New Economy." 16 countries reached zero population growth by 1997. 33 countries have stabilized population, which amounts to 14% of world population. It is estimated that by 2050 population will include an additional 3.6 billion people beyond the present 6 billion. About 60% of the added population will be in Asia, an increase from 3.4 billion in 1995 to 5.4 billion in 2050. China's current population of 1.2 billion will reach 1.5 billion. India's population is expected to rapidly rise from 930 million to 1.53 billion. Populations in the Middle East and North Africa are expected to double in size. Sub-Saharan population is expected to triple in size. By 2050, Nigeria will have 339 million people, which was the entire population of Africa in 1960. There is a great need to stabilize population in a number of currently unstabilized countries. In 1971, Bangladesh and Pakistan had the same population; however, by 2050, Pakistan, without a strong commitment to reducing population growth, will have 70 million more people than Bangladesh. Population stabilization will depend on removal of physical and social barriers that prevent women from using family planning services and thereby help them control their own unwanted fertility. Stabilization will require poverty alleviation and removal of the need for large families. Family size is reduced with lower infant and child mortality risk, increased education, a higher legal age of marriage, and investment in stabilization programs. Solutions to global population growth cannot wait for health reform and budget deficit reductions. PMID:12293723

  8. [sustainability indicators] : 2012 Description of indicator

    E-print Network

    of the total area of land in the Sunshine Coast Region available for agricultural production. Why for agricultural production. How is it measured? Data for this indicator have been sourced from the Australian related to the gross value of agricultural production is estimated for individual commodities

  9. Toward Master Social Indicators.

    ERIC Educational Resources Information Center

    Stanford Research Inst., Menlo Park, CA.

    This paper outlines an approach to devising master social indicators which reflect conditions in a major area of human concern. There are five principal sections: Section I is an introduction; Section II sketches a heuristic model for categorizing indicator concepts, and suggests how a hierarchically organized scheme of indicators can be…

  10. Risk Indicators Introduction

    E-print Network

    Neirotti, Juan Pablo

    1 Risk Indicators Introduction This paper is designed to prompt high-level discussion over potential indicators of the risk of the failure of a provider's quality assurance processes. It outlines Education (QAA) to determine such indicators some contextual considerations to their use in a `risk

  11. ECOLOGICAL INDICATOR OVERVIEW

    EPA Science Inventory

    The Ecological Indicator Program in NERL is developing indicators for two key purposes. The first is to characterize the biological condition of shallow streams and large rivers. The second is to develop diagnostic indicators to evaluate the causes of impairment to these commun...

  12. Energy-conservation indicators

    SciTech Connect

    Belzer, D.B.

    1982-06-01

    A series of Energy Conservation Indicators were developed for the Department of Energy to assist in the evaluation of current and proposed conservation strategies. As descriptive statistics that signify current conditions and trends related to efficiency of energy use, indicators provide a way of measuring, monitoring, or inferring actual responses by consumers in markets for energy services. Related sets of indicators are presented in some 30 one-page indicator summaries. Indicators are shown graphically, followed by several paragraphs that explain their derivation and highlight key findings. Indicators are classified according to broad end-use sectors: Aggregate (economy), Residential, Commercial, Industrial, and transportation. In most cases annual time series information is presented covering the period 1960 through 1981.

  13. Welding-Current Indicator

    NASA Technical Reports Server (NTRS)

    Hensley, Milton C.; Huston, Steven W.; Kroy, Ralph E.

    1990-01-01

    Light flashes on to indicate high current. Simple, inexpensive display circuit indicates when 3,000-A welding current flows in welding gun. Onset of welding current induces voltage and current in 1,000-turn, 28-gauge copper-wire coil. Single-transistor amplifier amplifies induced current, energizing light-emitting diode (LED) connected to collector of transistor. Light from LED gives simple, direct indication of welding current.

  14. Wellbore stability

    SciTech Connect

    Cheatham, J.B.

    1984-06-01

    A variety of factors can cause wellbore instabilities. Shale hydration can develop swelling pressures that may cause hole failures. Balanced activity oil muds and polymer muds provide means for controlling this type of hole instability. The wellbore fluid pressure must not exceed the fracturing pressure and must be greater than the blowout pressure. In geopressured formations the difference between the upper and lower bounds on wellbore pressure can be small. Low wellbore pressure also can lead to hole collapse and to solid particle influx. Predictive methods have been developed during the past 4 decades for dealing with these various causes of hole instability. Elastic-plastic analysis methods are available for computing stresses around inclined holes with static and moving formation pore fluids. Yield conditions can account for strain softening during plastic flow of the rock around the wellbore. However, improved constitutive relations are needed to provide a more realistic description of the mechanical behavior of rock such as including the effects of rock anisotropy. Better in-situ earth stress determinations and physical rock-properties measurements can aid greatly in providing improved wellbore stability control. With continued progress in the areas described in this article, wellbore stability engineering should become less of an art and more of an engineering science.

  15. Cobb's Red Cabbage Indicator.

    ERIC Educational Resources Information Center

    Cobb, Vicki

    1998-01-01

    Describes the use of an indicator made from the pigment in red cabbage. Cabbage is grated then soaked in water. When the water is a strong red, the cabbage is strained out. The cabbage-juice indicator is then used to test for acids and bases. Includes a list of good foods to test for acidity and alkalinity. (PVD)

  16. Retractable Visual Indicator Assembly

    NASA Technical Reports Server (NTRS)

    Hackler, George R. (Inventor); Gamboa, Ronald J. (Inventor); Dominquez, Victor (Inventor)

    1998-01-01

    A retractable indicator assembly may be mounted on a container which transmits air through the container and removes deleterious gases with an activated charcoal medium in the container. The assembly includes: an elongate indicator housing has a chamber therein; a male adaptor with an external threads is used for sealing engagement with the container; a plug located at the upper end of the housing; a housing that includes a transparent wall portion for viewing at least a portion of the chamber; a litmus indicator, moveable by a retractable rod from a retracted position within the container to an extended position within the chamber of the housing; and an outer housing that is secured to the upper end of the rod, and protects the indicator housing while the litmus indicator is in its normally retracted position. The assembly may be manually manipulated between its extended position wherein the litmus indicator may be viewed through the transparent wall of the indicator housing, and a retracted position wherein the outer housing encloses the indicator housing and engages the exterior of the container.

  17. Dark shading indicates shelving

    E-print Network

    Petta, Jason

    Dark shading indicates shelving for oversize books Campus Telephone N Nassau Street Studies Reading Room (SHS) History Reference Collection (SH) Graduate Study Graduate Study (SNE) Graduate Study Reading Room A-1D Reading Room A-1E A-18F A-17C Grey hatching indicates construction zone X 23

  18. School Readiness Indicator Items.

    ERIC Educational Resources Information Center

    Calkins, Julia; Ling, Thomson; Moore, Eric; Halle, Tamara; Hair, Beth; Moore, Kris; Zaslow, Marty

    This report provides a compilation of indicators of school readiness used in national, state, and local surveys in the United States, delineating the advantages and disadvantages for each indicator. The report begins with a legend to assist in interpreting the tables and includes contact information for national and state surveys. The remainder of…

  19. Carbon dioxide concentration indicator

    NASA Technical Reports Server (NTRS)

    King, P. H.

    1972-01-01

    Device will provide visual indication of concentration of carbon dioxide. It consists of small amounts of absorbent material contained in semipermeable membrane and device to detect color changes. Material will absorb quantity of carbon dioxide proportional to carbon dioxide concentration in atmosphere. Amount of absorption is indicated by color change.

  20. Tamper indicating bolt

    DOEpatents

    Blagin, Sergei V.; Barkanov, Boris P.

    2004-09-14

    A tamper-indicating fastener has a cylindrical body with threads extending from one end along a portion of the body, and a tamper indicating having a transducer for converting physical properties of the body into electronic data; electronics for recording the electronic data; and means for communicating the recorded information to a remote location from said fastener. The electronics includes a capacitor that varies as a function of force applied by the fastener, and non-volatile memory for recording instances when the capacitance varies, providing an indication of unauthorized access.

  1. Stabilizing brokerage

    PubMed Central

    Stovel, Katherine; Golub, Benjamin; Milgrom, Eva M. Meyersson

    2011-01-01

    A variety of social and economic arrangements exist to facilitate the exchange of goods, services, and information over gaps in social structure. Each of these arrangements bears some relationship to the idea of brokerage, but this brokerage is rarely like the pure and formal economic intermediation seen in some modern markets. Indeed, for reasons illuminated by existing sociological and economic models, brokerage is a fragile relationship. In this paper, we review the causes of instability in brokerage and identify three social mechanisms that can stabilize fragile brokerage relationships: social isolation, broker capture, and organizational grafting. Each of these mechanisms rests on the emergence or existence of supporting institutions. We suggest that organizational grafting may be the most stable and effective resolution to the tensions inherent in brokerage, but it is also the most institutionally demanding. PMID:22198763

  2. On the crisis stability of a submarine deterrent

    SciTech Connect

    Canavan, G.H.

    1992-05-01

    Without defenses, stability indices fall monotonically as the number of submarine-launched ballistic missiles (SLBMs) is reduced. For few SLBMs, the favorable stability properties of the survivable SLBMs are masked by the unfavorable stability properties of the non-survivable land missiles. With ground-based interceptor (GBI) defenses, stability initially falls faster. The number of GBIs could be increased gradually to minimize their impact on stability.

  3. Sustainability Indicators and Metrics

    EPA Science Inventory

    Sustainability is about preserving human existence. Indicators and metrics are absolutely necessary to provide at least a semi-quantitative assessment of progress towards or away from sustainability. Otherwise, it becomes impossible to objectively assess whether progress is bei...

  4. Industrial energy use indices 

    E-print Network

    Hanegan, Andrew Aaron

    2009-05-15

    Energy use index (EUI) is an important measure of energy use which normalizes energy use by dividing by building area. Energy use indices and associated coefficients of variation are computed for major industry categories ...

  5. Health expectancy indicators.

    PubMed Central

    Robine, J. M.; Romieu, I.; Cambois, E.

    1999-01-01

    An outline is presented of progress in the development of health expectancy indicators, which are growing in importance as a means of assessing the health status of populations and determining public health priorities. PMID:10083720

  6. ENVIRONMENTAL AND SOCIOECONOMIC INDICATORS

    E-print Network

    Pennycook, Steve

    between desirable features, costs, and feasibility often determine the choice of indicators. 4 Managed Feedstock Logistics Conversion Biofuel Distribution End use Resource conditions Fuel type Transport Storage Individual perspective: Feedstock production Feedstock Logistics Conversion to Biofuel Biofuel Logistics

  7. ENVIRONMENTAL PUBLIC HEALTH INDICATORS

    EPA Science Inventory

    Environmental Public Health Indicators (EPHIs), quantitative measures of health factors and environmental influences tracked over time, can be used to identify specific areas and populations for intervention and prevention efforts and to evaluate the outcomes of implemented polic...

  8. Stability of missile forces and defenses

    SciTech Connect

    Canavan, G.H.

    1997-04-01

    This note derives the exchange equation for mixes of missiles and defenses and discusses the impact on stability of varying their relative proportions. For fixed offenses increasing defenses decreases stability until first strikes fall to zero. The same is true of decreasing offenses for fixed defenses, although the decrease in indices is smaller. A judicious increase in defenses and decrease in offenses should effect that transition with minimum loss of stability.

  9. Stability of Metronidazole Suspensions.

    PubMed

    Donnelly, Ronald F; Ying, James

    2015-01-01

    Metronidazole is an antiprotozoal agent used in the treatment of bacterial and protozoal anaerobic infections. The objectives of this study were to develop concentrated metronidazole suspensions that are inexpensive and easy to prepare and determine the stability of these suspensions after storage in amber polyvinyl chloride bottles at room temperature (23°C) and under refrigeration (5°C). Metronidazole suspensions (50 mg/mL) were prepared from powder using Ora-Blend or simple syrup as the vehicles. Samples were collected in triplicate from each container on days 0, 7, 14, 28, 56, and 93. Samples were assayed using a high-performance liquid chromatography method that had been validated as stability indicating. Color, change in physical appearance, and pH were also monitored at each time interval. There was no apparent change in color or physical appearance. The pH values changed by less than 0.20 units over the 93 days. The stability of metronidazole suspensions compounded from United States Pharmacopeia powder using Ora-Blend or simple syrup and packaged in amber polyvinyl chloride bottles was determined to be 93 days when stored at either room temperature or under refrigeration. PMID:26714365

  10. Uranium mill tailings stabilization

    SciTech Connect

    Hartley, J.N.; Koehmstedt, P.L.; Esterl, D.J.; Freeman, H.D.

    1980-02-01

    Uranium mill tailings pose a potential radiation health hazard to the public. Therefore, stabilization or disposal of these tailings in a safe and environmentally sound way is needed to minimize radon exhalation and other environmental hazards. One of the most promising concepts for stabilizing U tailings is the use of asphalt emulsion to contain radon and other hazardous materials within uranium tailings. This approach is being investigated at the Pacific Northwest Laboratory. Results of these studies indicate that a radon flux reduction of greater than 99% can be obtained using either a poured-on/sprayed-on seal (3.0 to 7.0 mm thick) or an admixture seal (2.5 to 12.7 cm thick) containing about 18 wt % residual asphalt. A field test was carried out in June 1979 at the Grand Junction tailings pile in order to demonstrate the sealing process. A reduction in radon flux ranging from 4.5 to greater than 99% (76% average) was achieved using a 15.2-cm (6-in.) admix seal with a sprayed-on top coat. A hydrostatic stabilizer was used to apply the admix. Following compaction, a spray coat seal was applied over the admix as the final step in construction of a radon seal. Overburden was applied to provide a protective soil layer over the seal. Included in part of the overburden was a herbicide to prevent root penetration.

  11. Supersonic Wave Interference Affecting Stability

    NASA Technical Reports Server (NTRS)

    Love, Eugene S.

    1958-01-01

    Some of the significant interference fields that may affect stability of aircraft at supersonic speeds are briefly summarized. Illustrations and calculations are presented to indicate the importance of interference fields created by wings, bodies, wing-body combinations, jets, and nacelles.

  12. Stabilization of H2 by Organic Acids

    E-print Network

    Yu, Fangqun

    Stabilization of H2 SO4 ­H2 O Clusters by Organic Acids A.B. Nadykto1 and F. Yu1 Abstract While understood. In the present study, bonding among formic, acetic and benzoic acids, sulfuric acid, ammonia. The stabilizing effect of formic, acetic, and benzoic acids is found to be close that of ammonia that indicates

  13. Residential Stability and Academic Sense of Control

    ERIC Educational Resources Information Center

    Gigliotti, Richard J.

    1976-01-01

    Suggests that stability level of an individual and the community in which he operates is directly related to a child's sense of control and consequently his achievement in school. Findings indicate that for whites, community stability is positively and significantly related to sense of control, with the inverse for blacks. (Author/AM)

  14. Proportioning the airplane for lateral stability

    NASA Technical Reports Server (NTRS)

    Donlan, C. J.

    1976-01-01

    Proportioning for lateral aircraft control included: (1) directional stability (slope of curve of yawing moment coefficient against sideslip), and (2) effective dihedral factor (slope of curve of rolling moment coefficient against sideslip). Basic forces influencing the directional stability of aircraft are indicated. Propeller side force, basic fuselage yaw, and vertical tail side force contributed to yaw moment about center of gravity.

  15. Indicator Systems and Evaluation

    NASA Technical Reports Server (NTRS)

    Canright, Shelley; Grabowski, Barbara

    1995-01-01

    Participants in the workshop session were actively engaged in a hands-on, minds-on approach to learning about indicators and evaluation processes. The six hour session was broken down into three two hour sessions. Each session was built upon an instructional model which moved from general understanding to specific IITA application. Examples and practice exercises served to demonstrate tand reinforce the workshop concepts. Each successive session built upon the previous session and addressed the major steps in the evaluation process. The major steps covered in the workshop included: project descriptions, writing goals and objectives for categories, determining indicators and indicator systems for specific projects, and methods and issues of data collection. The workshop served as a baseline upon which the field centers will build during the summer in undertaking a comprehensive examination and evaluation of their existing K-12 education projects.

  16. MATLAB Stability and Control Toolbox Trim and Static Stability Module

    NASA Technical Reports Server (NTRS)

    Kenny, Sean P.; Crespo, Luis

    2012-01-01

    MATLAB Stability and Control Toolbox (MASCOT) utilizes geometric, aerodynamic, and inertial inputs to calculate air vehicle stability in a variety of critical flight conditions. The code is based on fundamental, non-linear equations of motion and is able to translate results into a qualitative, graphical scale useful to the non-expert. MASCOT was created to provide the conceptual aircraft designer accurate predictions of air vehicle stability and control characteristics. The code takes as input mass property data in the form of an inertia tensor, aerodynamic loading data, and propulsion (i.e. thrust) loading data. Using fundamental nonlinear equations of motion, MASCOT then calculates vehicle trim and static stability data for the desired flight condition(s). Available flight conditions include six horizontal and six landing rotation conditions with varying options for engine out, crosswind, and sideslip, plus three take-off rotation conditions. Results are displayed through a unique graphical interface developed to provide the non-stability and control expert conceptual design engineer a qualitative scale indicating whether the vehicle has acceptable, marginal, or unacceptable static stability characteristics. If desired, the user can also examine the detailed, quantitative results.

  17. Enzymatic temperature change indicator

    DOEpatents

    Klibanov, Alexander M. (Newton, MA); Dordick, Jonathan S. (Iowa City, IA)

    1989-01-21

    A temperature change indicator is described which is composed of an enzyme and a substrate for that enzyme suspended in a solid organic solvent or mixture of solvents as a support medium. The organic solvent or solvents are chosen so as to melt at a specific temperature or in a specific temperature range. When the temperature of the indicator is elevated above the chosen, or critical temperature, the solid organic solvent support will melt, and the enzymatic reaction will occur, producing a visually detectable product which is stable to further temperature variation.

  18. Enhanced stability and dechlorination activity of pre-synthesis stabilized nanoscale FePd particles

    NASA Astrophysics Data System (ADS)

    Sakulchaicharoen, Nataphan; O'Carroll, Denis M.; Herrera, Jose E.

    2010-11-01

    Nanoscale zero-valent iron (NZVI) particles are promising materials for the in-situ remediation of a wide variety of source zone contaminants. This study presents the results of a systematic investigation of the stability of bimetallic FePd nanoparticle suspensions in water and their capability to degrade trichloroethylene (TCE) synthesized in the presence of various stabilizers (i.e., carboxymethyl cellulose (CMC), polyvinylpyrrolidone (PVP), and guar gum). Results indicate a dramatic improvement in FePd suspension stability when the stabilizer is present in the matrix during the nanoparticle synthesis step. Stability enhancement is controlled by iron nanoparticle/stabilizer electrostatic and steric interactions, which are a function of the molecular structure of the stabilizer. Stabilization mechanisms differed for each stabilizer with CMC and guar gum exhibiting the best nanoparticle suspension stability improvement. Results suggest that the complexation of iron precursors with the stabilizer, during synthesis, plays a key role in nZVI stability improvement. In case of guar gum, gelation during synthesis significantly increased suspension viscosity, enhancing suspension stability. The capability of these materials to degrade TCE was also investigated. Results demonstrated that when stabilizers were present in the matrix dechlorination rates increased significantly. FePd nanoparticles in CMC had the highest observed rate constant; however the highest surface area-normalized rate constant was obtained from FePd stabilized in PVP360K. Results from this study can be used to aid in the selection of appropriate iron nanoparticle stabilizers. Stabilizer selection should be assessed on a case by case basis as no stabilizer will meet the needs of all in-situ remediation applications.

  19. Trends & Indicators: Enrollment Period

    ERIC Educational Resources Information Center

    Harney, John O.

    2011-01-01

    Since New England Board of Higher Education (NEBHE) began publishing tables and charts exploring "Trends & Indicators" in New England higher education more than a half-century ago, few figures have grabbed as much attention as college "enrollment" data. These local, state, regional and national data go beyond simple headcounts of students going to…

  20. Fluorescent Gage Indication

    NASA Technical Reports Server (NTRS)

    Barns, C. E.; Gilbaugh, B. L.; Gin, B.; Holt, W. L.; Lesak, P.; Mancini, R.; Spencer, H. F.

    1985-01-01

    Transfer of dye shows quality of contact between two mating parts. Mating parts checked for fit by spreading fluorescent dye on one, making brief light contact with other, and looking (under UV light) for transferred dye. Dye offers greater visibility under ultraviolet illumination, allowing better indication of how precisely parts match and what areas interfere.

  1. Dark shading indicates shelving

    E-print Network

    Petta, Jason

    Dark shading indicates shelving for oversize books Campus Telephone N Nassau Street Seminar Room Hellenic Studies Reading Room (SHS) History Reference Collection (SH) Graduate Study Graduate Study (SNE) Graduate Study Reading Room A-1D Reading Room A-1E Firestone Renovation Room A-19D A-18D A

  2. Landscape-based Indicators

    EPA Science Inventory

    The report is based on data and experience gained through the GLNPO-funded Great Lakes Coastal Wetland Consortium (GLCWC) and the EPA-STAR funded Great Lakes Ecological Indicators Project (GLEI). EPA-MED author Trebitz and other MED personnel were collaborators on the GLEI proje...

  3. Amniocentesis: indications and complications.

    PubMed

    Vrettos, A S; Koliopoulos, C; Panayotou, P P

    1975-02-01

    Transabdominal amniocentesis is described and our experience with this method is presented. No severe maternal complications were recorded. In two cases accidental puncture of fetal blood vessels in pregnancies over 40 weeks led to delivery by cesarean section. We believe that, although fetal complications are rare, the indications for amniocentesis should be significant enough to discount the hazards of the procedure. PMID:1116906

  4. Triboluminescent indicator system

    DOEpatents

    Goods, Steven H. (Livermore, CA); Dentinger, Paul M. (Sunol, CA); Whinnery, Jr., Leroy L. (Danville, CA)

    2003-06-24

    There is provided a light emitting device comprising a plurality of triboluminescent particles dispersed throughout a low density, frangible body and activated by rapidly crushing the body in order to transfer mechanical energy to some portion of the particles. The light emitted by these mechanically excited particles is collected and directed into a light conduit and transmitted to a detector/indicator means.

  5. Stability at low symmetric force levels

    SciTech Connect

    Canavan, G.H.

    1997-09-01

    At low force levels stability indices depend primarily on the number of vulnerable missiles and the number of weapons on them. The index reduces to a product of the number of vulnerable missiles and the differences between normalized second and first strikes by vulnerable weapons. As the number of weapons per vulnerable missile decreases, the index rapidly approaches stability. Further reductions in vulnerable and survivable missiles and weapons do not affect stability, although they do reduce first and second strikes. Modest weapon reconstitution degrades stability significantly.

  6. [Indications for parathyroidectomy].

    PubMed

    Oertli, D

    2007-06-13

    The standard of care for primary hyperparathyroidism is surgical removal of all hyperfunctional parathyroid tissue. In experienced hands, parathyroidectomy is successful in 95-99% of cases with a very low complication rate. Surgery is indicated for all patients with symptomatic primary hyperparathyroidism. Asymptomatic individuals should also be surgically treated when patients are younger than 50 years, have severe hypercalcemia, markedly reduced creatinine clearance and/or profound osteopenia (according to the NIH Consensus Conference 2002). A precise preoperative localisation of parathyroid adenomas using cervical ultrasound and Sestamibi scintigraphy enables to elect the minimally invasive parathyroidectomy in most of the cases. Nowadays, the former routine of open bilateral cervical exploration is indicated only if preoperative localisation was not successful and hyperplasia of all four parathyroid glands is anticipated. PMID:17616036

  7. LEADING WITH LEADING INDICATORS

    SciTech Connect

    PREVETTE, S.S.

    2005-01-27

    This paper documents Fluor Hanford's use of Leading Indicators, management leadership, and statistical methodology in order to improve safe performance of work. By applying these methods, Fluor Hanford achieved a significant reduction in injury rates in 2003 and 2004, and the improvement continues today. The integration of data, leadership, and teamwork pays off with improved safety performance and credibility with the customer. The use of Statistical Process Control, Pareto Charts, and Systems Thinking and their effect on management decisions and employee involvement are discussed. Included are practical examples of choosing leading indicators. A statistically based color coded dashboard presentation system methodology is provided. These tools, management theories and methods, coupled with involved leadership and employee efforts, directly led to significant improvements in worker safety and health, and environmental protection and restoration at one of the nation's largest nuclear cleanup sites.

  8. New indications for antidepressants.

    PubMed

    Schatzberg, A F

    2000-01-01

    The second and third generation of antidepressants, i.e., the selective serotonin reuptake inhibitors, nefazodone, venlafaxine, and mirtazapine, are proving to be useful in a variety of seemingly diverse disorders, including most anxiety disorders. In addition to receiving approval from the U.S. Food and Drug Administration (FDA) for major depressive disorder, some of the newer antidepressants have received FDA approval for other disorders, e.g., generalized anxiety disorder (venlafaxine), bulimia nervosa (fluoxetine), obsessive-compulsive disorder (fluvoxamine, paroxetine, sertraline, and fluoxetine), social phobia (paroxetine), panic disorder (sertraline, paroxetine), and posttraumatic stress disorder (sertraline). In controlled studies, these agents have also shown usefulness in premenstrual dysphoric disorder, borderline personality disorder, obesity, smoking cessation, and alcoholism. This article describes the new and potential indications for recently developed antidepressants and the studies that suggested these indications. PMID:10926050

  9. Indices of thyroid epidemiology

    PubMed Central

    Kalra, Sanjay; Kumar, Arun; Jarhyan, Prashant; Unnikrishnan, Ambika Gopalakrishnan

    2015-01-01

    This brief communication proposes various indices of epidemicity and endemicity which may be used to predict the future prevalence of hypothyroidism. Taking advantage of knowledge related to the natural progression of autoimmune thyroid disease, it uses data from two recent Indian epidemiological studies to assess the epidemicity or endemicity of thyroid disease in the country. The hypothesis generated in this communication will be of help to clinicians as well as policy makers.

  10. Conformationally selective biophysical assay for influenza vaccine potency determination.

    PubMed

    Wen, Yingxia; Han, Liqun; Palladino, Giuseppe; Ferrari, Annette; Xie, Yuhong; Carfi, Andrea; Dormitzer, Philip R; Settembre, Ethan C

    2015-10-01

    Influenza vaccines are the primary intervention for reducing the substantial health burden from pandemic and seasonal influenza. Hemagglutinin (HA) is the most important influenza vaccine antigen. Subunit and split influenza vaccines are formulated, released for clinical use, and tested for stability based on an in vitro potency assay, single-radial immunodiffusion (SRID), which selectively detects HA that is immunologically active (capable of eliciting neutralizing or hemagglutination inhibiting antibodies in an immunized subject). The time consuming generation of strain-specific sheep antisera and calibrated antigen standards for SRID can delay vaccine release. The limitation in generating SRID reagents was evident during the early days of the 2009 pandemic, prompting efforts to develop more practical, alternative, quantitative assays for immunologically active HA. Here we demonstrate that, under native conditions, trypsin selectively digests HA produced from egg or mammalian cell in monovalent vaccines that is altered by stress conditions such as reduced pH, elevated temperature, or deamidation, leaving native, pre-fusion HA, intact. Subsequent reverse-phase high pressure liquid chromatography (RP-HPLC) can separate trypsin-resistant HA from the digested HA. Integration of the resulting RP-HPLC peak yields HA quantities that match well the values obtained by SRID. Therefore, trypsin digestion, to pre-select immunologically active HA, followed by quantification by RP-HPLC is a promising alternative in vitro potency assay for influenza vaccines. PMID:26348403

  11. Predicting vegetation-stabilized dune field morphology

    NASA Astrophysics Data System (ADS)

    Barchyn, Thomas E.; Hugenholtz, Chris H.

    2012-09-01

    The morphology of vegetation-stabilized dune fields on the North American Great Plains (NAGP) mostly comprises parabolic dunes; stabilized barchan and transverse dunes are rare, with the exception of transverse and barchan mega-dunes in the Nebraska Sand Hills. We present a hypothesis from a numerical dune field model explaining the vegetation-stabilized morphology of dunes under unidirectional wind. Simulations with a range of initial dune morphologies (closely-spaced transverse to disperse barchans) indicate that stabilized morphology is determined by the ratio of slipface deposition rate to deposition tolerance of vegetation. Slipface deposition rate is related to dune height, flux, and celerity. With a fixed depositional tolerance, large, slow-moving dunes have low slipface deposition rates and ‘freeze’ in place once vegetation is introduced. Relatively small, fast dunes have high slipface deposition rates and evolve into parabolic dunes, often colliding during stabilization. Our hypothesis could explain differences in stabilized morphology across the NAGP and elsewhere.

  12. Characterization and purification of iodinated bovine thyrotropin by high performance liquid chromatography

    SciTech Connect

    Stanton, P.G.; Hearn, M.T.

    1986-08-01

    Reversed-phase (RP) HPLC, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and gel permeation chromatography have been used to study the incorporation of 125I into bovine (b) TSH by the lactoperoxidase-catalyzed radioiodination procedure. Two preparations of (/sup 125/I)bTSH were studied, being freshly iodinated bTSH and tracer purified from this preparation by the method of receptor adsorption. It is demonstrated with these methods that both the alpha- and beta-subunits of bTSH are labeled with 125I, and that the tracer purified by receptor adsorption retains this incorporation pattern. However, the implied theoretical specific activity of (at least) 2 I atoms per TSH molecule (or approximately 140 muCi/micrograms) suggested by this result was not achieved, with observed tracer specific activity being 30-60 muCi/micrograms, indicating that hormone molecules with varying extents of labeling must exist. Evidence to support this was provided by comparison of the MIT/DIT ratios for the 2 tracer preparations. Receptor adsorption decreased the MIT/DIT ratio from 75:25 in the freshly iodinated bTSH to 93:7, indicating the selection of particular iodinated species. Tryptic mapping by RP-HPLC was used to study both tracer preparations, and it is shown that at least 14 iodine-containing tryptic peptides may be resolved for each preparation, which is greater than the theoretical maximum of 13 peptides if every tyrosine was labeled and tryptic cleavage occurred at all possible lysine and arginine residues. Tracer heterogeneity was also studied by purification using RP-HPLC. Selection of peak fractions demonstrated that intact (/sup 125/I)bTSH may be recovered from RP-HPLC which in TSH radioreceptor assay exhibit increased assay sensitivity, increased saturable binding, and decreased nonsaturable binding.

  13. Slickenside kinematic indicators

    NASA Astrophysics Data System (ADS)

    Doblas, Miguel

    1998-09-01

    A new classification of slickenside kinematic indicators is presented based on 61 criteria. These slickensides have been subdivided into eleven major groups: `V' or crescentic markings, steps, fractures, trains of inclined planar structures, trailed material, asymmetric elevations, deformed elements, mineralogical/crystallographic orientations, asymmetric plan-view features, asymmetric cavities, and asymmetric folds. This classification constitutes a useful tool for geologists interested in the determination of the shear sense in fault surfaces bearing slickensides. Examples of application of this classification to natural fault surfaces at different scales are presented.

  14. Tamper-indicating seal

    DOEpatents

    Fiarman, S.; Degen, M.F.; Peters, H.F.

    1982-08-13

    There is disclosed a tamper-indicating seal that permits in the field inspection and detection of tampering. Said seal comprises a shrinkable tube having a visible pattern of markings which is shrunk over th item to be sealed, and a second transparent tube, having a second visible marking pattern, which is shrunk over the item and the first tube. The relationship between the first and second set of markings produces a pattern so that the seal may not be removed without detection. The seal is particularly applicable to UF/sub 6/ cylinder valves.

  15. Tamper indicating packaging

    SciTech Connect

    Baumann, M.J.; Bartberger, J.C.; Welch, T.D.

    1994-08-01

    Protecting sensitive items from undetected tampering in an unattended environment is crucial to the success of non-proliferation efforts relying on the verification of critical activities. Tamper Indicating Packaging (TIP) technologies are applied to containers, packages, and equipment that require an indication of a tamper attempt. Examples include: the transportation and storage of nuclear material, the operation and shipment of surveillance equipment and monitoring sensors, and the retail storage of medicine and food products. The spectrum of adversarial tampering ranges from attempted concealment of a pin-hole sized penetration to the complete container replacement, which would involve counterfeiting efforts of various degrees. Sandia National Laboratories (SNL) has developed a technology base for advanced TIP materials, sensors, designs, and processes which can be adapted to various future monitoring systems. The purpose of this technology base is to investigate potential new technologies, and to perform basic research of advanced technologies. This paper will describe the theory of TIP technologies and recent investigations of TIP technologies at SNL.

  16. Breathiness in Indic languages

    NASA Astrophysics Data System (ADS)

    Esposito, Christina; Khan, Sameeruddowla; Hurst, Alex

    2005-04-01

    Previous work on breathiness in Indic languages has focused on the acoustic properties of breathy oral stops in languages like Hindi ([bal] hair versus [bhal] forehead) or Bengali ([baSa] house versus [bhaSa] language). However, breathiness in Indic languages often extends to nasals (e.g., Marathi ([maar] beat versus [mhaar] a caste). It is unclear if languages such as Hindi and Bengali have breathy nasals in addition to breathy oral stops. This study addresses the following questions: (1) Are breathy nasals (Nh) acoustically different from N+h sequences, both in languages where they are phonemic and ones where they are not? (2) In sequences of a breathy stop and a modal nasal (e.g., Hindi [udhmi] naughty) where is the breathiness realized, if at all? To answer these questions, audio, aerodynamic, and electroglottographic recordings will be made of Hindi, Bengali, and Marathi speakers. It is hypothesized that acoustically breathy nasals in Hindi and Bengali will not be distinct from sequences of N+ h. We believe that this will also be true for the oral stops. In addition, it is believed that in sequences of breathy oral stop followed by a modal nasal (e.g., ChN), the breathiness will be produced on the nasal.

  17. Partial Characterization of Venom from the Colombian Spider Phoneutria Boliviensis (Aranae:Ctenidae)

    PubMed Central

    Estrada-Gomez, Sebastian; Vargas Muñoz, Leidy Johana; Lanchero, Paula; Segura Latorre, Cesar

    2015-01-01

    We report on the first studies on the characterization of venom from Phoneutria boliviensis (Aranae:Ctenidae) (F. O. Pickard-Cambridge, 1897), done with Colombian species. After the electrostimulation extraction process, the venom showed physicochemical properties corresponding to a colorless and water-soluble liquid with a density of 0.86 mg/mL and 87% aqueous content. P. boliviensis venom and RP-HPLC fractions showed hemolytic activity and hydrolyzed the synthetic substrate 4-nitro-3-octanoyloxy-benzoic acid, indicating the presence of phospholipases A2 enzymes. The electrophoretic profile showed an important protein content with molecular masses below 14 kDa, and differences between male and female protein content were also revealed. The RP-HPLC venom profile exposes differences between males and female content consistent with the electrophoretic profile. Five fractions collected from the RP-HPLC displayed significant larvicidal activity. Mass analysis indicates the presence of peptides ranging from 1047.71 to 3278.07 Da. Two peptides, Ctenitoxin-Pb48 and Ctenitoxin-Pb53, were partially identified using HPLC-nESI-MS/MS, which showed a high homology with other Ctenitoxins (family Tx3) from Phoneutria nigriventer, Phoneutria keyserlingi and Phoneutria reidyi affecting voltage-gated calcium receptors (Cav 1, 2.1, 2.2 and 2.3) and NMDA-glutamate receptors. PMID:26264023

  18. High Stability Engine Control (HISTEC)

    NASA Technical Reports Server (NTRS)

    DeLaat, John C.; Southwick, Robert D.; Gallops, George W.

    1996-01-01

    Future aircraft turbine engines, both commercial and military, must be able to successfully accommodate expected increased levels of steady-state and dynamic engine-face distortion. The current approach of incorporating a sufficient component design stall margin to tolerate these increased levels of distortion would significantly reduce performance. The objective of the High Stability Engine Control (HISTEC) program is to design, develop, and flight demonstrate an advanced, high-stability, integrated engine control system that uses measurement-based, real-time estimates of distortion to enhance engine stability. The resulting distortion tolerant control reduces the required design stall margin, with a corresponding increase in performance and decrease in fuel burn. The HISTEC concept, consisting of a Distortion Estimation System and a Stability Management Control, has been designed and developed. The Distortion Estimation System uses a small number of high-response pressure sensors at the engine face to calculate indicators of the type and extent of distortion in real time. The Stability Management Control, through direct control of the fan and compressor pressure ratio, accommodates the distortion by transiently increasing the amount of stall margin available based on information from the Distortion Estimation System. Simulation studies have shown the HISTEC distortion tolerant control is able to successfully estimate and accommodate time-varying distortion. Currently, hardware and software systems necessary for flight demonstration of the HISTEC concept are being designed and developed. The HISTEC concept will be flight tested in early 1997.

  19. Precipitation Indices Low Countries

    NASA Astrophysics Data System (ADS)

    van Engelen, A. F. V.; Ynsen, F.; Buisman, J.; van der Schrier, G.

    2009-09-01

    Since 1995, KNMI published a series of books(1), presenting an annual reconstruction of weather and climate in the Low Countries, covering the period AD 763-present, or roughly, the last millennium. The reconstructions are based on the interpretation of documentary sources predominantly and comparison with other proxies and instrumental observations. The series also comprises a number of classifications. Amongst them annual classifications for winter and summer temperature and for winter and summer dryness-wetness. The classification of temperature have been reworked into peer reviewed (2) series (AD 1000-present) of seasonal temperatures and temperature indices, the so called LCT (Low Countries Temperature) series, now incorporated in the Millennium databases. Recently we started a study to convert the dryness-wetness classifications into a series of precipitation; the so called LCP (Low Countries Precipitation) series. A brief outline is given here of the applied methodology and preliminary results. The WMO definition for meteorological drought has been followed being that a period is called wet respectively dry when the amount of precipitation is considerable more respectively less than usual (normal). To gain a more quantitative insight for four locations, geographically spread over the Low Countries area (De Bilt, Vlissingen, Maastricht and Uccle), we analysed the statistics of daily precipitation series, covering the period 1900-present. This brought us to the following definition, valid for the Low Countries: A period is considered as (very) dry respectively (very) wet if over a continuous period of at least 60 days (~two months) cq 90 days (~three months) on at least two out of the four locations 50% less resp. 50% more than the normal amount for the location (based on the 1961-1990 normal period) has been measured. This results into the following classification into five drought classes hat could be applied to non instrumental observations: Very wet period (+2): Wide scale river flooding, marshy acres and meadows.-Farmers cope with poor harvests of hay, grains, fruit etc. resulting in famines.-Late grape harvests, poor yield quantity and quality of wine. Wet period (+1): High water levels cq discharges of major rivers, tributaries and brooks, local river floodings, marshy acres and meadows in the low lying areas.-Wearisome and hampered agriculture. Normal (0) Dry period (-1): Low water levels cq discharges of major rivers, tributaries and brooks. Some brooks may dry up.-Summer half year: local short of yield of grass, hay and other forage.-Summer half year: moor-, peat- and forest fires. Very dry period (-2): Very low water levels cq discharges of major rivers and tributaries. Brooks and wells dry up. Serious shortage of drinking water; especially in summer.-Major agricultural damage, shortage of water, mortality stock of cattle. Shortage of grain. Flour can not be produced due to water mills running out of water, shortage of bread, bread riots, famines.-Large scale forest and peat areas, resulting in serious air pollution. Town fires. By verifying the historical evidence on these criterions, a series of 5 step indices ranging from very dry to very wet for summer and winter half year of the Low Countries was obtained. Subsequently these indices series were compared with the instrumentally observed seasonal precipitation sums for De Bilt (1735-2008), which is considered to be representative for the Central Netherlands. For winter (Oct-March) and summer half year (Apr.-Sept.) the accumulated precipitation amounts are calculated; these amounts are approximately normally distributed. Based on this distribution, the cumulative frequency distribution is calculated. By tabulating the number of summers in the pre-instrumental period 1201-1750 for each of the drought classes, a distribution is calculated which is then related to the modern accumulated precipitation distribution. Assuming that the accumulated precipitation amount has not been below (above) the mean precipitation minus (plus) three standard deviations for

  20. International energy indicators

    SciTech Connect

    Bauer, E.K.

    1981-02-01

    Extensive data are compiled for energy on the international scene and for the US. Data are indicated from the date given and into 1980 as far as available. Data are given for the international scene on: world crude oil production, 1975-to date; Iran: crude oil capacity, production, and shut-in, 1974-to date; Saudi Arabia: crude oil capacity, production, and shut-in, 1974-to date; OPEC (Ex-Iran and Saudi Arabia): capacity, production, and shut-in, 1974-to date; oil stocks: Free World, US, Japan, and Europe (landed), 1973-to date; petroleum consumption by industrial countries, 1973-to date; USSR crude oil production, 1974-to date; Free World and US nuclear generation capacity, 1973-to date. Data are supplied specifically for the US on US gross imports of crude oil and products, 1973-to date; landed cost of Saudi crude in current and 1974 dollars; US trade in bituminous coal, 1973-to date; summary of US merchandise trade, 1976-to date; and energy/GNP ratio.

  1. Entanglement-breaking indices

    NASA Astrophysics Data System (ADS)

    Lami, L.; Giovannetti, V.

    2015-09-01

    We study a set of new functionals (called entanglement-breaking indices) which characterize how many local iterations of a given (local) quantum channel are needed in order to completely destroy the entanglement between the system of interest over which the transformation is defined and an external ancilla. The possibility of contrasting the noisy effects introduced by the channel iterations via the action of intermediate (filtering) transformations is analyzed. We provide some examples in which our functionals can be exactly calculated. The differences between unitary and non-unitary filtering operations are analyzed showing that, at least for systems of dimension d larger than or equal to 3, the non-unitary choice is preferable (the gap between the performances of the two cases being divergent in some cases). For d = 2 (qubit case), on the contrary, no evidences of the presence of such gap is revealed: we conjecture that for this special case unitary filtering transformations are optimal. The scenario in which more general filtering protocols are allowed is also discussed in some detail. The case of a depolarizing noise acting on a two-qubit system is exactly solved in a general case.

  2. Workshop on Feedback Stabilization of MHD Stabilities

    SciTech Connect

    McGuire, K.; Kugel, H.; La Haye, R.; Mauel, M.; Nevins, W.; Prager, S.

    1996-12-31

    The feedback stabilization of MHD instabilities is an area of research that is critical for improving the performance and economic attractiveness of magnetic confinement devices. A Workshop dedicated to feedback stabilization of MHD instabilities was held from December 11-13, 1996 at the Princeton Plasma Physics Laboratory, Princeton NJ, USA. The resulting presentations, conclusions, and recommendations are summarized.

  3. Should researchers use single indicators, best indicators, or multiple indicators in structural equation models?

    PubMed Central

    2012-01-01

    Background Structural equation modeling developed as a statistical melding of path analysis and factor analysis that obscured a fundamental tension between a factor preference for multiple indicators and path modeling’s openness to fewer indicators. Discussion Multiple indicators hamper theory by unnecessarily restricting the number of modeled latents. Using the few best indicators – possibly even the single best indicator of each latent – encourages development of theoretically sophisticated models. Additional latent variables permit stronger statistical control of potential confounders, and encourage detailed investigation of mediating causal mechanisms. Summary We recommend the use of the few best indicators. One or two indicators are often sufficient, but three indicators may occasionally be helpful. More than three indicators are rarely warranted because additional redundant indicators provide less research benefit than single indicators of additional latent variables. Scales created from multiple indicators can introduce additional problems, and are prone to being less desirable than either single or multiple indicators. PMID:23088287

  4. Food Fortification Stability Study

    NASA Technical Reports Server (NTRS)

    Abdulmalik, T. O.; Cooper, M. R.; Douglas, G. L.

    2015-01-01

    NASA has established the goal of traveling beyond low-Earth orbit and extending manned exploration to Mars. The extended length of a Mars mission, along with the lack of resupply missions increases the importance of nutritional content in the food system. The purpose of this research is to assess the stability of vitamin supplementation in traditionally processed spaceflight foods. It is expected that commercially available fortificants will remain stable through long-duration missions if proper formulation, processing, and storage temperatures are all achieved. Five vitamins (vitamin E, vitamin K, pantothenic acid, folic acid, and thiamin) were blended into a vitamin premix (DSM, Freeport, TX); premixes were formulated to be compatible with current processing techniques (retort or freeze-dried), varied water activities (high or low), and packaging material. The overall goal of this process is to provide 25% of the recommended daily intake of each vitamin (per serving), following processing and two years of ambient storage. Four freeze-dried foods (Scrambled Eggs, Italian Vegetables, Potatoes Au Gratin, Noodles and Chicken) and four thermostabilized foods (Curry Sauce with Vegetables, Chicken Noodle Soup, Grilled Pork Chop, Rice with Butter) were produced (with and without the vitamin premix), to assess the impact of the added fortificant on color and taste, and to determine the stability of supplemental vitamins in spaceflight foods. The use of fortification in spaceflight foods appears to be a plausible mitigation step to inadequate nutrition. This is due to the ease of vitamin addition as well as the sustainability of the premixes through initial processing steps. Postprocessing analysis indicated that vitamin fortification with this premix did not immediately impact organoleptic properties of the food. At this stage, the largest hurdle to fortification is the preciseness to which vitamins can be added; the total amount of vitamins required for production is 10 - 20 grams, a minor percentage of the formulation. As demonstrated by the over-fortification measured in Italian Vegetables and Grilled Pork Chop, homogeneity may be difficult to achieve with such small amounts. Thus, pouch-to-pouch variability, over-fortification, and underfortification may ensue if a method for precise addition is not identified. Stability will continue to be evaluated over two years of storage at three temperatures, and future analysis should reveal the extent to which this issue should be a concern

  5. Automatic Stability of Airplanes

    NASA Technical Reports Server (NTRS)

    Haus, FR

    1932-01-01

    It is endeavored in this report to give a full outline of the problem of airplane stability and to classify the proposed solutions systematically. Longitudinal stability, which can be studied separately, is considered first. The combination of lateral and directional stabilities, which cannot be separated, will be dealt with later.

  6. Limits to Stability

    ERIC Educational Resources Information Center

    Cottey, Alan

    2012-01-01

    The author reflects briefly on what limited degree of global ecological stability and human cultural stability may be achieved, provided that humanity retains hope and does not give way to despair or hide in denial. These thoughts were triggered by a recent conference on International Stability and Systems Engineering. (Contains 5 notes.)

  7. The stability of solitons

    NASA Astrophysics Data System (ADS)

    Rybakov, Iu. P.

    Liapunov's direct method is used to analyze the stability of periodically time-dependent multidimensional soliton solutions. Necessary and sufficient conditions for the stability of charged solitons are formulated. The Hobart-Derrick theorem concerning the energy instability of multidimensional solitons is generalized, and it is shown that Q-theorem conditions are necessary for the stability of nodeless scalar solitons.

  8. Hydrolytic stability of synthetic oils

    SciTech Connect

    Echin, A.I.; Kondrat'eva, T.B.; Novosartov, G.T.

    1984-01-01

    This article investigates the hydrolytic stability for diisooctyl sebacate (DOS), the pentaerythritol and diethylene glycol esters of a C/sub 5/-C/sub 9/ synthetic fatty acid cut (PEE and DEGE), and synthetic oils based on these esters: VNII NP 50-1-4f, B-3V, and 36/1 KU-A. The hydrolysis rate was evaluated from the increase in concentration of acid formed in the process of hydrolysis at specific intervals of time. The dependence of the degree of hydrolysis on the content of water in the oil is examined. The results of the study of the hydrolytic stability of esters and synthetic oils show that the indexes most susceptible to change in the course of hydrolysis are the acid number of the oil and the pH and acid number of the water extract. The stability of the kinematic viscosity at /sup -/40/sup 0/C before and after hydrolysis and the absence of sludge after hydrolysis indicate that in the hydrolysis under these conditions, thermal and thermal-oxidative processes have practically no influence on the oil properties. It is determined that the low hydrolytic stability of the USSR diester oils is due to their content of certain additives that catalyze hydrolysis.

  9. Feedback stabilization initiative

    SciTech Connect

    1997-06-01

    Much progress has been made in attaining high confinement regimes in magnetic confinement devices. These operating modes tend to be transient, however, due to the onset of MHD instabilities, and their stabilization is critical for improved performance at steady state. This report describes the Feedback Stabilization Initiative (FSI), a broad-based, multi-institutional effort to develop and implement methods for raising the achievable plasma betas through active MHD feedback stabilization. A key element in this proposed effort is the Feedback Stabilization Experiment (FSX), a medium-sized, national facility that would be specifically dedicated to demonstrating beta improvement in reactor relevant plasmas by using a variety of MHD feedback stabilization schemes.

  10. Analytical and physicochemical characterisation of the senile cataract drug dipeptide ?-alanyl-L-histidine (carnosine).

    PubMed

    Abdelkader, Hamdy; Swinden, Julian; Pierscionek, Barbara K; Alany, Raid G

    2015-10-10

    This study presents a simple but sensitive HPLC chromatographic method with a stability-indicating assay for determination and physicochemical characterisation of L-carnosine, a promising senile cataract prophylactic agent. Chromatographic analysis was conducted using a reverse phase (RP)-HPLC system and an isocratic mobile phase of 98% v/v trifluoroacetic acid (0.1% v/v) and 2% v/v acetonitrile with detection at 220 nm. L-carnosine was subjected to stress conditions to force its degradation using chemical and thermal agents and was subsequently detected from its degradation products using ESI-MS. The lipophilicity of the drug and 1:1 drug to phospholipid complex (PC) mol/mol was determined by estimating the partition coefficient (P). Lipophilicity was greatly enhanced when L-carnosine was formulated as a phospholipid complex using the solvent evaporation method. L-carnosine-phospholipid complex could be a promising approach for effective delivery to the human lens as offers a potential novel treatment for senile cataract. PMID:26073114

  11. Purification and characterisation of plantaricin ZJ008, a novel bacteriocin against Staphylococcus spp. from Lactobacillus plantarum ZJ008.

    PubMed

    Zhu, Xuan; Zhao, Yizhen; Sun, Yalian; Gu, Qing

    2014-12-15

    A novel bacteriocin, plantaricin ZJ008 produced by Lactobacillus plantarum ZJ008 isolated from fresh milk, was purified by XAD 2, cation exchange chromatograph, gel chromatograph, and RP-HPLC. Mass spectrometry based on MALDI-TOF indicated that the bacteriocin had a molecular of 1334.77 Da. Only five of twenty amino acids could be identified by Edman degradation. This bacteriocin was highly thermostable (121°C, 30 min) and exhibited narrow pH stability (pH 4.0-5.0). It was sensitive to ?-Chymotrypsin, trypsin, papain, and pepsin. However it still had 80% of activity after treatment by proteinase K. The action mode of this peptide functioned as bactericidal, but it did not lead to lysis of cells. This bacteriocin exhibited broad-spectrum antimicrobial activity against tested Gram-positive and Gram-negative bacteria, especially Staphylococcus spp. These results suggested that this bacteriocin appears potentially very useful to control and inhibit Staphylococcus spp. in the food industry. PMID:25038669

  12. Reversed phase High Performance Liquid Chromatography used for the physicochemical and thermodynamic characterization of piceatannol/?-cyclodextrin complex.

    PubMed

    Messiad, Hanane; Amira-Guebailia, Habiba; Houache, Omar

    2013-05-01

    Piceatannol is one of resveratrol derivatives having health promoting potential. However, its low water-solubility and bioavailability could limit its use in both food and pharmaceutical fields. The aim of this work is the study of piceatannol complexation by ?-cyclodextrin (?-CD) in aqueous media. The complex formed could improve the bioavailability, the solubility and the stability of piceatannol. The method used was based on RP-HPLC in which, ?-CD was added to methanol/water mixtures mobile phases. The apparent formation constant of piceatannol/?-cyclodextrin complex was determined. Within the concentration interval studied (0-4 mM), whenever the concentration of ?-CD increased, retention time of piceatannol decreased; indicating an enhancement of solubility due to the formation of the piceatannol/?-CD complex. The formation constants (KF) of the piceatannol/?-CD complex varied significantly with both the methanol concentration in the water-methanol mixture and the temperature. Moreover, in all the physicochemical conditions tested, the stoichiometry of piceatannol/?-CD complex was 1:1. Finally, the thermodynamic parameters were determined: ?G°=-13.123 kJ mol(-1), ?H°=-33. 265 kJ mol(-1) and ?S°=-67.559 J mol(-1) K(-1). PMID:23537743

  13. Methionine oxidation accelerates the aggregation and enhances the neurotoxicity of the D178N variant of the human prion protein.

    PubMed

    Feng, Boya; Wang, Zonglin; Liu, Ting; Jin, Rui; Wang, Shaobo; Wang, Wei; Xiao, Gengfu; Zhou, Zheng

    2014-12-01

    The D178N mutation of the prion protein (PrP) results in the hereditary prion disease fatal familial insomnia (FFI). Little is known regarding the effects of methionine oxidation on the pathogenesis of D178N-associated FFI. In the present study, we found that the D178N variant was more susceptible to oxidation than wild-type PrP, as indicated by reverse-phase high performance liquid chromatography (RP-HPLC) and mass spectrometry (MS) analysis. Circular dichroism (CD), differential scanning calorimetry (DSC), thioflavin T (ThT) binding assay studies demonstrated that methionine oxidation decreased the structural stability of the D178N variant, and the oxidized D178N variant exhibited a greater propensity to form ?-sheet-rich oligomers and aggregates. Moreover, these aggregates of oxidized D178N PrP were more resistant to proteinase K (PK) digestion. Additionally, using fluorescence confocal microscopy, we detected a high degree of aggregation in D178N-transfected Neuro-2a (N2a) cells after treatment with hydrogen peroxide (H2O2). Furthermore, the oxidation and consequent aggregation of the D178N variant induced greater apoptosis of N2a cells, as monitored using flow cytometry. Collectively, these observations suggest that methionine oxidation accelerates the aggregation and enhances the neurotoxicity of the D178N variant, possibly providing direct evidence to link the pathogenesis of D178N-associated FFI with methionine oxidation. PMID:25281825

  14. Gas turbine combustor stabilization by heat recirculation

    NASA Technical Reports Server (NTRS)

    Ganji, A.; Short, J.; Branch, M. C.; Oppenheim, A. K.

    1975-01-01

    The feasibility of heat recirculation for stabilization of lean mixtures and emission reduction has been studied in detail for a typical aircraft gas turbine combustor. Thermodynamic calculations have indicated temperature and heat recirculation rates for operation of the combustor over a range of combustion zone equivalence ratios and for varying modes of desired engine operation. Calculations indicate the feasibility of stabilizing the combustion zone at equivalence ratios as low as 0.2 with achievable heat recirculation rates. Detailed chemical kinetic calculations suggest that combustor heat release is maintained with reaction completion substantially before the NO forming reactions, even though CO is rapidly oxidized in this same region.

  15. RAPID COMMUNICATIONS IN MASS SPECTROMETRY Rapid Commun. Mass Spectrom. 2005; 19: 25282538

    E-print Network

    Evans, Jason

    spectrometry (RP-HPLC/APCI-MS),22­29 and on RP-HPLC coupled with electrospray ionization tandem mass spectrometry (HPLC/ ESI-MS/MS),30­33 have been developed for positional ana- lysis of TAGs. These methods fatty acid hydrolysis products in each of the digested fractions. RP-HPLC provides superb fractionation

  16. RANGELAND HEALTH ATTRIBUTES AND INDICATORS FOR QUALITATIVE ASSESSMENT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Panels of experts from the Society for Range Management and the National Research Council proposed that status of rangeland ecosystems could be ascertained by evaluating an ecological site¿s potential to conserve soil resources and by a series of indicators for ecosystem processes and site stability...

  17. Thermal stability of an interface-stabilized skyrmion lattice.

    PubMed

    Sonntag, A; Hermenau, J; Krause, S; Wiesendanger, R

    2014-08-15

    The thermal stability of the magnetic nano-skyrmion lattice in the monolayer Fe/Ir(111) is investigated using temperature dependent spin-polarized scanning tunneling microscopy. Our experiments show that the skyrmion lattice disappears at a temperature of T_{c}=27.8??K, indicating a loss of long-range magnetic order. At second-layer iron islands the lattice is pinned and local order persists at temperatures above T_{c}. The findings are explained in terms of the complex magnetic interactions involved in the formation of the skyrmion lattice. PMID:25170729

  18. Edible Acid-Base Indicators.

    ERIC Educational Resources Information Center

    Mebane, Robert C.; Rybolt, Thomas R.

    1985-01-01

    Reports on the colors observed during titrations of 15 natural indicators obtained from common fruits and vegetables. These edible indicators can be used for a variety of teacher demonstrations or for simple student experiments. (JN)

  19. Evaluation of stability of live attenuated camelpox vaccine stabilized with different stabilizers and reconstituted with various diluents.

    PubMed

    Prabhu, M; Bhanuprakash, V; Venkatesan, G; Yogisharadhya, R; Bora, D P; Balamurugan, V

    2014-05-01

    In this study, thermostability of a Vero cell attenuated live camelpox vaccine under conventional lyophilization conditions has been evaluated. Three stabilizers were used separately for freeze-drying the vaccine and the stability of the vaccine, both in freeze-dried and reconstituted forms at different temperatures was assessed. The study revealed that the camelpox vaccine lyophilized with TAA stabilizer found superior with a shelf life of 44 months, 227 days, 22 days and 20 days at 4, 25, 37 and 45 °C, respectively followed by LS stabilizer. In terms of half-life, TAA stabilizer proved better followed by LS and BUGS stabilizers at all temperatures except at 25 °C in which LS found relatively superior. Among the four diluents viz. 1x PBS (phosphate buffered saline, pH 7.4), 0.85% NaCl, distilled water and 1 M MgSO4, PBS was a better diluent followed by 0.85% NaCl. Both the diluents maintained the infectivity titer more than the minimum effective dose (3 log10TCID50 with a maximum titre of 6.53 log10TCID50 in both the diluents) for 60 h at 37 and 45 °C. However, 1 M MgSO4 found less suitable for camelpox vaccine dilution. The study indicates that the TAA and 1× PBS are the choice of stabilizer and diluent, respectively for camelpox vaccine. PMID:24657207

  20. Stability of holographic superconductors

    SciTech Connect

    Kanno, Sugumi; Soda, Jiro

    2010-10-15

    We study the dynamical stability of holographic superconductors. We first classify perturbations around black hole background solutions into vector and scalar sectors by means of a 2-dimensional rotational symmetry. We prove the stability of the vector sector by explicitly constructing the positive definite Hamiltonian. To reveal a mechanism for the stabilization of a superconducting phase, we construct a quadratic action for the scalar sector. From the action, we see the stability of black holes near a critical point is determined by the equation of motion for a charged scalar field. We show the effective mass of the charged scalar field in hairy black holes is always above the Breitenlohner-Freedman bound near the critical point due to the backreaction of a gauge field. It implies the stability of the superconducting phase. We also argue that the stability continues away from the critical point.

  1. Stabilizing Grout Compatibility Study

    SciTech Connect

    HARBOUR, JOHNR.

    2004-05-19

    This report provides data that will be used to formulate the stabilizing grout and includes experimental results for Tc-99 stabilization by two reagents, (1) ground granulated blast furnace slag (GGBFS) and (2) surface treated hydroxyapatite (HA). One or both of these reagents are being considered by CH2M HILL for incorporation in the binder portion (matrix portion without sand) of the stabilizing grout. The technical basis for identifying the grout ingredient(s) for stabilizing technetium (Tc-99) will be provided by researchers at the Savannah River Technology Center (SRTC) in a subsequent report.

  2. Divertor Stabilization in Mirrors

    SciTech Connect

    Pastukhov, V.P.

    2005-01-15

    Divertor stabilization is considered as an alternative MHD stability concept for mirror-based plasma confinement systems. The discussed concept is based on thermodynamics and self-organization of magnetized plasmas, contrary to the conventional MHD stabilization, based on the presence of averaged 'magnetic well'. We show that self-organized plasma maintenance near a relaxed marginally-stable state with decreasing pressure profile can be realized in essentially non-paraxial longitudinally linked mirror cells restricted by a joint divertorlike magnetic separatrix with one or several magnetic field nulls at the plasma edge. Brief history, basic principles, and main advantages of the divertor stabilization concept are discussed.

  3. Process for stabilization of coal liquid fractions

    DOEpatents

    Davies, Geoffrey (Boston, MA); El-Toukhy, Ahmed (Alexandria, EG)

    1987-01-01

    Coal liquid fractions to be used as fuels are stabilized against gum formation and viscosity increases during storage, permitting the fuel to be burned as is, without further expensive treatments to remove gums or gum-forming materials. Stabilization is accomplished by addition of cyclohexanol or other simple inexpensive secondary and tertiary alcohols, secondary and tertiary amines, and ketones to such coal liquids at levels of 5-25% by weight with respect to the coal liquid being treated. Cyclohexanol is a particularly effective and cost-efficient stabilizer. Other stabilizers are isopropanol, diphenylmethanol, tertiary butanol, dipropylamine, triethylamine, diphenylamine, ethylmethylketone, cyclohexanone, methylphenylketone, and benzophenone. Experimental data indicate that stabilization is achieved by breaking hydrogen bonds between phenols in the coal liquid, thereby preventing or retarding oxidative coupling. In addition, it has been found that coal liquid fractions stabilized according to the invention can be mixed with petroleum-derived liquid fuels to produce mixtures in which gum deposition is prevented or reduced relative to similar mixtures not containing stabilizer.

  4. Thermal stability of grafted fibers. [Gamma radiation

    SciTech Connect

    Sundardi, F.; Kadariah; Marlianti, I.

    1983-10-01

    Presented the experimental results on the study of thermal stability of grafted fibers, i.e., polypropylene-, polyester-, and rayon-grafted fibers. These fibers were obtained by radiation grafting processes using hydrophylic monomers such as 1-vinyl 2-pyrolidone, acrylic acid, N-methylol acrylamide, and acrylonitrile. The thermal stability of the fibers was studied using a Shimadzu Thermal Analyzer DT-30. The thermal stability of the fibers, which can be indicated by the value of the activation energy for thermal degradation, was not improved by radiation grafting. The degree of improvement depends on the thermal stability of the monomers used for grafting. The thermal stability of a polypropylene fiber, either a grafted or an ungrafted one, was found to be inferior compared to the polyester of a rayon fiber, which may be due to the lack of C=O and C=C bonds in the polypropylene molecules. The thermal stability of a fiber grafted with acrylonitrile monomer was found to be better than that of an ungrafted one. However, no improvement was detected in the fibers grafted with 1-vinyl 2-pyrrolidone monomer, which may be due to the lower thermal stability of poly(1-vinyl-2-pyrrolidone), compared to the polypropylene or polyester fibers. 17 figures, 3 tables.

  5. Stability threshold approach for complex dynamical systems

    E-print Network

    Vladimir V. Klinshov; Vladimir I. Nekorkin; Jürgen Kurths

    2015-12-11

    A new measure to characterize stability of complex dynamical systems against large perturbation is suggested, the stability threshold (ST). It quantifies the magnitude of the weakest perturbation capable to disrupt the system and switch it to an undesired dynamical regime. In the phase space, the stability threshold corresponds to the "thinnest site" of the attraction basin and therefore indicates the most "dangerous" direction of perturbations. We introduce a computational algorithm for quantification of the stability threshold and demonstrate that the suggested approach is effective and provides important insights. The generality of the obtained results defines their vast potential for application in such fields as engineering, neuroscience, power grids, Earth science and many others where robustness of complex systems is studied.

  6. How dead ends undermine power grid stability.

    PubMed

    Menck, Peter J; Heitzig, Jobst; Kurths, Jürgen; Joachim Schellnhuber, Hans

    2014-01-01

    The cheapest and thus widespread way to add new generators to a high-voltage power grid is by a simple tree-like connection scheme. However, it is not entirely clear how such locally cost-minimizing connection schemes affect overall system performance, in particular the stability against blackouts. Here we investigate how local patterns in the network topology influence a power grid's ability to withstand blackout-prone large perturbations. Employing basin stability, a nonlinear concept, we find in numerical simulations of artificially generated power grids that tree-like connection schemes--so-called dead ends and dead trees--strongly diminish stability. A case study of the Northern European power system confirms this result and demonstrates that the inverse is also true: repairing dead ends by addition of a few transmission lines substantially enhances stability. This may indicate a topological design principle for future power grids: avoid dead ends. PMID:24910217

  7. Thermal stability of radiation curable materials

    NASA Astrophysics Data System (ADS)

    Thalacker, V. P.; Boettcher, T. E.

    The thermal stability of radiation curable materials was determined via TGA measurements and related to functionality, chemical type, and cure conditions. The results indicate that Tri-, Tetra-, and Penta- functional acrylates are more thermally stable than lower functional acrylates and that acrylates have better thermal stability than methacrylates. A comparison of EB, UV, and thermal curing conditions for TMPTA showed that EB-cured material was more thermally stable than UV and that thermally cured TMPTA was the least stable. The thermal stability of acrylated epoxy oligomers is again in the order of increasing functionality The 13C carbonyl region and oxygen permeability measurements were used to determine the extent of cure and then related to thermal stability.

  8. Phase stability of transition metal dichalcogenide by competing ligand field stabilization and charge density wave

    NASA Astrophysics Data System (ADS)

    C, Santosh K.; Zhang, Chenxi; Hong, Suklyun; Wallace, Robert M.; Cho, Kyeongjae

    2015-09-01

    Transition metal dichalcogenides (TMDs) have been investigated extensively for potential application as device materials in recent years. TMDs are found to be stable in trigonal prismatic (H), octahedral (T), or distorted octahedral (Td) coordination of the transition metal. However, the detailed understanding of stabilities of TMDs in a particular phase is lacking. In this work, the detailed TMD phase stability using first-principles calculations based on density functional theory (DFT) has been investigated to clarify the mechanism of phase stabilities of TMDs, consistent with the experimental observation. Our results indicate that the phase stability of TMDs can be explained considering the relative strength of two competing mechanisms: ligand field stabilization of d-orbitals corresponding to transition metal coordination geometry, and charge density wave (CDW) instability accompanied by a periodic lattice distortion (PLD) causing the phase transition in particular TMDs.

  9. Memristor-integrated voltage-stabilizing supercapacitor system.

    PubMed

    Liu, Bin; Liu, Boyang; Wang, Xianfu; Wu, Xinghui; Zhao, Wenning; Xu, Zhimou; Chen, Di; Shen, Guozhen

    2014-08-01

    Voltage-stabilized supercapacitors: A single supercapacitor formed with PCBM/Pt/IPS nanorod-array electrodes is designed and delivers enhanced areal capacitance, capacitance retention, and excellent electrical stability under bending, while a significant voltage-decrease is observed during the discharging process. Once integrated with the memristor, the memristor-integrated supercapacitor systems deliver an extremely low voltage-drop, indicating greatly enhanced voltage-stabilizing features. PMID:24805149

  10. Dimensional stability of natural fibers

    SciTech Connect

    Driscoll, Mark S.

    2013-04-19

    One of the main problems associated with the use of natural fibers as reinforcing agents in composites is their uptake of moisture. Many natural fibers are lignocellulosic, which causes them to swell and shrink as the amount of available moisture changes. Swelling and shrinking can cause composites to prematurely fail. This paper presents the results of a preliminary study that considers the use of two different low molecular weight monomers, hydroxyethyl methacrylate (HEMA) and hydroxyethyl acrylate (HEA), polymerized by electron beam ionizing radiation, to dimensionally stabilize natural fibers. Eight different treatments consisting of varying amounts of monomer, encapsulating agent, and cross-linkers, were evaluated for their ability to dimensionally stabilize sisal fiber. Results indicate that both polymerized HEA and HEMA can reduce the swelling of sisal fiber. The effectiveness of HEA and HEMA can be further enhanced with the use of a cross-linker (SR 454). The use of hydroxylated monomers to dimensionally stabilize natural fibers may play an important role in reducing delamination and improving fiber-resin adhesion in composites.

  11. Thermal stability of sulfonated polymers

    SciTech Connect

    Audibert, A.; Argillier, J.F.

    1995-11-01

    Polyacrylamides which are used in oil applications i.e. polymer flooding and water based muds, are hydrolyzed versus time and temperature. This leads to a lack of tolerance towards electrolyte contamination and to a rapid degradation inducing a loss of their properties. Modifications of polyacrylamide structure have been proposed to postpone their thermal stability to higher temperatures. Monomers such as acrylamido methylpropane sulfonate (AMPS) or sulfonated styrene/maleic anhydride can be used to prevent acrylamide comonomer from hydrolysis. The aim of this work is to study under controlled conditions, i.e. anaerobic atmosphere, neutral pH, the stability of sulfonated polymers in order to distinguish between hydrolysis and radical degradation reactions. It has been observed that up to 100 C, the AMPS group is stable and protects the acrylamide function from hydrolysis up to 80%. At higher temperature, even the hydrolysis of the AMPS group occurs, giving acrylate and {beta},{beta} dimethyl taurine, with a kinetics that depends on temperature and time. Degradation in terms of molecular weight then occurs indicating that it follows a radical decarboxylation reaction. It can be limited either by the use of free radical scavenger or when the polymer is in the presence of a mineral phase such as bentonite. These results provide valuable data for the determination of the limits of use of sulfonated copolymers and guidelines for optimizing chemical structure of sulfonated polymers used in water based formulation, in particular to enhance their thermal stability.

  12. Global and local indices for characterizing biomolecular flexibility and rigidity.

    PubMed

    Pfleger, Christopher; Radestock, Sebastian; Schmidt, Elena; Gohlke, Holger

    2013-01-30

    Understanding flexibility and rigidity characteristics of biomolecules is a prerequisite for understanding biomolecular structural stability and function. Computational methods have been implemented that directly characterize biomolecular flexibility and rigidity by constraint network analysis. For deriving maximal advantage from these analyses, their results need to be linked to biologically relevant characteristics of a structure. Such links are provided by global and local measures ("indices") of biomolecular flexibility and rigidity. To date, more than 14 indices are available with sometimes overlapping or only vague definitions. We present concise definitions of these indices, analyze the relation between, and the scope and limitations of them, and compare their informative value. For this, we probe the structural stability of the calcium binding protein ?-lactalbumin as a showcase, both in the "ground state" and after perturbing the system by changing the network topology. In addition, we introduce three indices for the first time that extend the application domain of flexibility and rigidity analyses. The results allow us to provide guidelines for future studies suggesting which of these indices could best be used for analyzing, understanding, and quantifying structural features that are important for biomolecular stability and function. Finally, we make suggestions for proper index notations in future studies to prevent the misinterpretation and to facilitate the comparison of results obtained from flexibility and rigidity analyses. PMID:23007873

  13. Methods for obtaining desired helicopter stability characteristics

    NASA Technical Reports Server (NTRS)

    Gustafson, F B; Tapscott, Robert J

    1954-01-01

    A brief summary is made of methods available to the helicopter designer for obtaining desired stability characteristics by modifications to the airframe design. The discussion is based on modifications made during the establishment of flying-qualities criteria and includes sample indications of theoretical studies of additional methods.

  14. Stability of the pumpkin balloon

    NASA Astrophysics Data System (ADS)

    Baginski, Frank

    A large axisymmetric balloon with positive differential pressure, e.g., a sphere, leads to high film stresses. These can be significantly reduced by using a lobed pumpkin-like shape re-enforced with tendons. A number of schemes have been proposed to achieve a cyclically symmetric pumpkin-shape at full inflation, including the constant bulge angle (CBA) design and the constant bulge radius (CBR) design. The authors and others have carried out stability studies of CBA and CBR designs and found instabilities under various conditions. While stability seems to be a good indicator of deployment problems for large balloons under normal ascent conditions, one cannot conclude that a stable design will deploy reliably. Nevertheless, stability analysis allows one to quantify certain deployment characteristics. Ongoing research by NASA's Balloon Program Office utilizes a new design approach developed by Rodger Farley, NASA/GSFC, that takes into account film and tendon strain. We refer to such a balloon as a constant stress (CS) pumpkin design. In June 2006, the Flight 555-NT balloon (based on a hybrid CBR/CBA design) developed an S-cleft and did not deploy. In order to understand the S-cleft phenomena and study a number of aspects related to the CS-design, a series of inflation tests were conducted at TCOM, Elizabeth City, NC in 2007. The test vehicles were 27 meter diameter pumpkins distinguished by their respective equatorial bulge angles (BA). For example, BA98 indicates an equatorial bulge angle of 98° . BA90, BA55, and BA00 are similarly defined. BA98 was essentially a one-third scale version of of the Flight 555 balloon (i.e., 12 micron film instead of 38.1 micron, mini-tendons, etc.). BA90 and BA55 were Farley CS-designs. BA00 was derived from the BA55 design so that a flat chord spanned adjacent tendons. In this paper, we will carry out stability studies of BA98, BA90, BA55, and BA00. We discuss the deployment problem of pumpkin balloons in light of 2007 inflation test results and flight data. In previous stability work, we added constant uniform perturbations to the design in our sensitivity studies. Here, we consider non-uniform perturbation as well. For example, a tendon may have a certain average slack strain s when measured over its entire length. However, there will be local variations ˆ about s. We explore such sensitivities via case studies. ˆ

  15. Stabilized radio frequency quadrupole

    DOEpatents

    Lancaster, H.D.; Fugitt, J.A.; Howard, D.R.

    1984-12-25

    Disclosed is a long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator. 5 figs.

  16. Forces Stabilizing Proteins

    PubMed Central

    Pace, C. Nick; Scholtz, J. Martin; Grimsley, Gerald R.

    2014-01-01

    The goal of this article is to summarize what has been learned about the major forces stabilizing proteins since the late 1980s when site-directed mutagenesis became possible. The following conclusions are derived from experimental studies of hydrophobic and hydrogen bonding variants. 1. Based on studies of 138 hydrophobic interaction variants in 11 proteins, burying a –CH2– group on folding contributes 1.1 ± 0.5 kcal/mol to protein stability. 2. The burial of nonpolar side chains contributes to protein stability in two ways: first, a term that depends on the removal of the side chains from water and, more importantly, the enhanced London dispersion forces that result from the tight packing in the protein interior. 3. Based on studies of 151 hydrogen bonding variants in 15 proteins, forming a hydrogen bond on folding contributes 1.1 ± 0.8 kcal/mol to protein stability. 4. The contribution of hydrogen bonds to protein stability is strongly context dependent. 5. Hydrogen bonds by side chains and peptide groups make similar contributions to protein stability. 6. Polar group burial can make a favorable contribution to protein stability even if the polar group is not hydrogen bonded. 7. Hydrophobic interactions and hydrogen bonds both make large contributions to protein stability. PMID:24846139

  17. Stabilized radio frequency quadrupole

    DOEpatents

    Lancaster, Henry D. (Orinda, CA); Fugitt, Jock A. (Berkeley, CA); Howard, Donald R. (Danville, CA)

    1984-01-01

    A long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator.

  18. Homological stabilizer codes

    SciTech Connect

    Anderson, Jonas T.

    2013-03-15

    In this paper we define homological stabilizer codes on qubits which encompass codes such as Kitaev's toric code and the topological color codes. These codes are defined solely by the graphs they reside on. This feature allows us to use properties of topological graph theory to determine the graphs which are suitable as homological stabilizer codes. We then show that all toric codes are equivalent to homological stabilizer codes on 4-valent graphs. We show that the topological color codes and toric codes correspond to two distinct classes of graphs. We define the notion of label set equivalencies and show that under a small set of constraints the only homological stabilizer codes without local logical operators are equivalent to Kitaev's toric code or to the topological color codes. - Highlights: Black-Right-Pointing-Pointer We show that Kitaev's toric codes are equivalent to homological stabilizer codes on 4-valent graphs. Black-Right-Pointing-Pointer We show that toric codes and color codes correspond to homological stabilizer codes on distinct graphs. Black-Right-Pointing-Pointer We find and classify all 2D homological stabilizer codes. Black-Right-Pointing-Pointer We find optimal codes among the homological stabilizer codes.

  19. Predicting vegetation-stabilized dune morphology

    NASA Astrophysics Data System (ADS)

    Barchyn, T.; Hugenholtz, C.

    2012-04-01

    The morphology of vegetation-stabilized dune fields on the North American Great Plains mostly comprises parabolic dunes; stabilized barchan and transverse dunes are rare. One notable exception is the Nebraska Sand Hills (NSH), where massive grass-covered barchan and transverse dunes bear proof of former desert-like conditions. We present a hypothesis from a numerical dune field model to explain the vegetation-stabilized morphology of dunes. The model incorporates a growth curve that preferentially grows vegetation in regions of sediment deposition with a sharp drop in growth at the peak depositional tolerance of vegetation, qualitatively matching biological response to erosion and deposition. Simulations on a range of pre-stabilization dune morphologies, from large closely-spaced transverse dunes to small dispersed barchans, indicate that the stabilized morphology is largely determined by the ratio of slipface deposition rate to peak depositional tolerance of vegetation. Conceptually, slipface deposition rate is related to dune height and celerity. By keeping depositional tolerance constant (representing a constant vegetation type and climate) the model shows that large slow-moving dunes have low slipface deposition rates and essentially 'freeze' in place once vegetation is introduced, retaining their pre-vegetation morphology. Small fast-moving dunes have higher slipface deposition rates and evolve into parabolic dunes. We hypothesize that, when barchan and transverse dunes are subjected to a stabilizing climate shift that increases vegetation growth rate, they retain their pre-stabilization morphology if deposition rates are below the depositional tolerance of stabilizing vegetation, otherwise they become parabolic dunes. This could explain why NSH dunes are stabilized in barchan and transverse morphologies while elsewhere on the Great Plains dune fields are dominated by smaller parabolic dunes.

  20. Stability of Heterogeneous Ecosystem

    NASA Astrophysics Data System (ADS)

    Liu, Yang-Yu; Yan, Gang; Barabasi, Alber-Laszlo

    2014-03-01

    Stability of ecosystem measures the tendency of a community to return to equilibrium after environmental perturbation, which is severely constrained by the underlying network structure. Despite significant advances in uncovering the relationship between stability and network structure, little attention has been paid to the impact of the degree heterogeneity that exists in real ecosystems. Here we show that for networks with mixed interactions of competition and mutualism the degree heterogeneity always destabilizes the ecosystem. Surprisingly, for predator-prey interactions (e.g., food webs) high heterogeneity is destabilizing yet moderate heterogeneity is stabilizing. These findings deepen our understanding of the stability of real ecosystems and may also have implications in studying the stability of more general complex dynamical systems.

  1. Rotorcraft aeroelastic stability

    NASA Technical Reports Server (NTRS)

    Ormiston, Robert A.; Warmbrodt, William G.; Hodges, Dewey H.; Peters, David A.

    1988-01-01

    Theoretical and experimental developments in the aeroelastic and aeromechanical stability of helicopters and tilt-rotor aircraft are addressed. Included are the underlying nonlinear structural mechanics of slender rotating beams, necessary for accurate modeling of elastic cantilever rotor blades, and the development of dynamic inflow, an unsteady aerodynamic theory for low-frequency aeroelastic stability applications. Analytical treatment of isolated rotor stability in hover and forward flight, coupled rotor-fuselage stability in hover and forward flight, and analysis of tilt-rotor dynamic stability are considered. Results of parametric investigations of system behavior are presented, and correlation between theoretical results and experimental data from small and large scale wind tunnel and flight testing are discussed.

  2. Validation of the Goal Attainment Scale of Stabilization

    ERIC Educational Resources Information Center

    Balkin, Richard S.

    2013-01-01

    Factor structure for the Goal Attainment Scale of Stabilization was evaluated using separate samples for exploratory factor analysis and confirmatory factor analysis. Results indicated a 25-item two-factor solution. The Goal Attainment Scale of Stabilization may be useful in identifying the extent to which adolescents in crisis meet therapeutic…

  3. Fit Indices Versus Test Statistics

    ERIC Educational Resources Information Center

    Yuan, Ke-Hai

    2005-01-01

    Model evaluation is one of the most important aspects of structural equation modeling (SEM). Many model fit indices have been developed. It is not an exaggeration to say that nearly every publication using the SEM methodology has reported at least one fit index. Most fit indices are defined through test statistics. Studies and interpretation of…

  4. CRITICAL EVALUATION OF ECOLOGICAL INDICATORS

    EPA Science Inventory

    EPA's Office of Research and Development (ORD) has prepared fifteen technical guidelines to evaluate the suitability of an ecological indicator in a monitoring program. The guidelines were fashioned to provide a consistent framework for indicator review and to provide guidance fo...

  5. Sustainability Indicators: A Scientific Assessment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The book entitled "Sustainability Indicators: A Scientific Assessment," which was a product of a multi-location research effort and workshoip held in Prague Czech Republic, is reviewed for readers of the Journal of Enviromental Quality (JEQ). The overview and chapters on biodiversity indicators and ...

  6. Quality Indicators for Learning Analytics

    ERIC Educational Resources Information Center

    Scheffel, Maren; Drachsler, Hendrik; Stoyanov, Slavi; Specht, Marcus

    2014-01-01

    This article proposes a framework of quality indicators for learning analytics that aims to standardise the evaluation of learning analytics tools and to provide a mean to capture evidence for the impact of learning analytics on educational practices in a standardised manner. The criteria of the framework and its quality indicators are based on…

  7. A Primer on Performance Indicators.

    ERIC Educational Resources Information Center

    Research File, 1995

    1995-01-01

    This report discusses the use of performance indicators (PIs) in higher education, focusing on definitions, frameworks, examples, and implications for universities. It notes that demands for accountability have led to intense interest in university performance measures, and that early indicators simply described the university or the system and…

  8. Science Indicators and Science Priorities.

    ERIC Educational Resources Information Center

    Brooks, Harvey

    1982-01-01

    Discusses science/society interface and difficulties involved in developing realistic science indicators. Topics include: intrinsic vs. extrinsic indicators; four problems society faces as a result of technological activities (toxic chemicals, radioactive wastes, auto safety, cancer); research and development (R&D) priorities; international…

  9. Dispersal and metapopulation stability

    PubMed Central

    Haegeman, Bart; Loreau, Michel

    2015-01-01

    Metapopulation dynamics are jointly regulated by local and spatial factors. These factors may affect the dynamics of local populations and of the entire metapopulation differently. Previous studies have shown that dispersal can stabilize local populations; however, as dispersal also tends to increase spatial synchrony, its net effect on metapopulation stability has been controversial. Here we present a simple metapopulation model to study how dispersal, in interaction with other spatial and local processes, affects the temporal variability of metapopulations in a stochastic environment. Our results show that in homogeneous metapopulations, the local stabilizing and spatial synchronizing effects of dispersal cancel each other out, such that dispersal has no effect on metapopulation variability. This result is robust to moderate heterogeneities in local and spatial parameters. When local and spatial dynamics exhibit high heterogeneities, however, dispersal can either stabilize or destabilize metapopulation dynamics through various mechanisms. Our findings have important theoretical and practical implications. We show that dispersal functions as a form of spatial intraspecific mutualism in metapopulation dynamics and that its effect on metapopulation stability is opposite to that of interspecific competition on local community stability. Our results also suggest that conservation corridors should be designed with appreciation of spatial heterogeneities in population dynamics in order to maximize metapopulation stability. PMID:26557427

  10. Identification of protein stability determinants in chloroplasts

    PubMed Central

    Apel, Wiebke; Schulze, Waltraud X; Bock, Ralph

    2010-01-01

    Although chloroplast protein stability has long been recognised as a major level of post-translational regulation in photosynthesis and gene expression, the factors determining protein stability in plastids are largely unknown. Here, we have identified stability determinants in vivo by producing plants with transgenic chloroplasts that express a reporter protein whose N- and C-termini were systematically modified. We found that major stability determinants are located in the N-terminus. Moreover, testing of all 20 amino acids in the position after the initiator methionine revealed strong differences in protein stability and indicated an important role of the penultimate N-terminal amino acid residue in determining the protein half life. We propose that the stability of plastid proteins is largely determined by three factors: (i) the action of methionine aminopeptidase (the enzyme that removes the initiator methionine and exposes the penultimate N-terminal amino acid residue), (ii) an N-end rule-like protein degradation pathway, and (iii) additional sequence determinants in the N-terminal region. PMID:20545891

  11. Developing indicators for European birds

    PubMed Central

    Gregory, Richard D; van Strien, Arco; Vorisek, Petr; Gmelig Meyling, Adriaan W; Noble, David G; Foppen, Ruud P.B; Gibbons, David W

    2005-01-01

    The global pledge to deliver ‘a significant reduction in the current rate of biodiversity loss by 2010’ is echoed in a number of regional and national level targets. There is broad consensus, however, that in the absence of conservation action, biodiversity will continue to be lost at a rate unprecedented in the recent era. Remarkably, we lack a basic system to measure progress towards these targets and, in particular, we lack standard measures of biodiversity and procedures to construct and assess summary statistics. Here, we develop a simple classification of biodiversity indicators to assist their development and clarify purpose. We use European birds, as example taxa, to show how robust indicators can be constructed and how they can be interpreted. We have developed statistical methods to calculate supranational, multi-species indices using population data from national annual breeding bird surveys in Europe. Skilled volunteers using standardized field methods undertake data collection where methods and survey designs differ slightly across countries. Survey plots tend to be widely distributed at a national level, covering many bird species and habitats with reasonable representation. National species' indices are calculated using log-linear regression, which allows for plot turnover. Supranational species' indices are constructed by combining the national species' indices weighted by national population sizes of each species. Supranational, multi-species indicators are calculated by averaging the resulting indices. We show that common farmland birds in Europe have declined steeply over the last two decades, whereas woodland birds have not. Evidence elsewhere shows that the main driver of farmland bird declines is increased agricultural intensification. We argue that the farmland bird indicator is a useful surrogate for trends in other elements of biodiversity in this habitat. PMID:15814345

  12. Borehole stability in shales

    SciTech Connect

    Bol, G.M.; Wong, S.W.; Davidson, C.J.; Woodland, D.C.

    1994-06-01

    Downhole mud/shale interaction can only be properly understood if rock mechanical, shale hydration, and fluid transport phenomena are taken into account. This paper presents a review of Koninklijke Shell E P Laboratorium's research on borehole stability in shales. Mechanisms relevant to shale stability, including pore pressure penetration (the gradual increase in pore pressure resulting from high mud weight), capillary threshold pressures, compressive and tensile failure, postfailure stabilization, hydration stress, inhibition, and osmotic phenomena are discussed. The authors attempt to integrate these mechanisms into a comprehensive model for shale behavior.

  13. Stabilization precision control methods of photoelectric aim-stabilized system

    NASA Astrophysics Data System (ADS)

    Song, Xiaoru; Chen, Hua; Xue, Yonggang

    2015-09-01

    To solve the question that photoelectric aim-stabilized system can be controlled with high precision and stability, this paper researches a new photoelectric aim-stabilized control algorithm, analyzes the photoelectric aim-stabilized system architecture, sets up stability control system mathematical model, designs the stability of the photoelectric aim-stabilized LSSVM identification and control system, discusses uncertain factors and calculates the LSSVM parameters by the Chaos theory, gives the predictive controller model by the LSSVM and designs new photoelectric aim-stabilized system. Through the simulation calculation and experimental analysis, new photoelectric aim-stabilized control algorithm was verified; the results show the new photoelectric aim-stabilized control method can meet the demand of high precision control in photoelectric aim-stabilized system.

  14. COLIPHAGES AS INDICATORS OF ENTEROVIRUSES

    EPA Science Inventory

    Coliphages were monitored in conjunction with indicator bacteria and enteric viruses in a drinking water plant modified to reduce trihalomethane (THM) production. Coliphages could be detected in the source water by direct innoculation and sufficient coliphages were detected in en...

  15. Investigation of Some Metallochromic Indicators.

    ERIC Educational Resources Information Center

    Jones, A. V.; Nelson, M.

    1979-01-01

    Presents some introductory experiments involving the reaction between EDTA and several metal ions using metallochromic indicators. The experiments represent familiar reactions and are followed by suggestions for extension into areas of discovery work by students. (Author/SA)

  16. EVALUATION GUIDELINES FOR ECOLOGICAL INDICATORS

    EPA Science Inventory

    This document presents fifteen technical guidelines to evaluate the suitability of an ecological indicator for a particular monitoring program. The guidelines are organized within four evaluation phrases: conceptual relevance, feasibility of implementation, response variability...

  17. Fluid sphere: Stability problem and dimensional constraint

    NASA Astrophysics Data System (ADS)

    Rahaman, Farook; Pradhan, Anirudh; Ahmed, Nasr; Ray, Saibal; Saha, Bijan; Rahaman, Mosiur

    2015-04-01

    We study different dimensional fluids inspired by noncommutative geometry which admit conformal Killing vector (CKV). The solutions of the Einstein field equations were examined specifically for five different set of spacetime. We calculate the active gravitational mass and impose stability conditions of the fluid sphere. The analysis thus carried out immediately indicates that at four dimension only one can get a stable configuration for any spherically symmetric stellar system and any other dimension, lower or higher, becomes untenable as far as the stability of a system is concerned.

  18. Advances in vaccine stability monitoring technology.

    PubMed

    Zweig, Stephen E

    2006-08-14

    Electronic time-temperature indicator (eTTI) monitors can be programmed to exactly follow the stability characteristics of vaccines with a high degree of realism. The monitors have a visual output, enabling vaccine status to be assessed at a glance, and can also output more detailed statistical data. When packaged with vaccine vials in groups of about 10 vials per box, the eTTI can remain with a vaccine throughout most of the vaccine's lifetime. The monitors can detect essentially all cold-chain breaks, and can detect issues, such as inadvertent freezing, that are presently not detected by other vaccine stability monitors such as Vaccine Vial Monitors (VVM). PMID:16759766

  19. Weld width indicates weld strength

    NASA Technical Reports Server (NTRS)

    Nunes, A. C. J.; Novak, H. L.; Mcllwain, M. C.

    1982-01-01

    Width of butt weld in 2219-T87 aluminum has been found to be more reliable indicator of weld strength than more traditional parameters of power input and cooling rate. Yield stress and ultimate tensile strength tend to decrease with weld size. This conclusion supports view of many professional welders who give priority to weld geometry over welding energy or cooling rate as indicator of weld quality.

  20. Stabilizer state breeding

    SciTech Connect

    Hostens, Erik; Dehaene, Jeroen; Moor, Bart de

    2006-12-15

    We present a breeding protocol that distills pure copies of any stabilizer state from noisy copies and a pool of predistilled pure copies of the same state, by means of local Clifford operations, Pauli measurements, and classical communication.

  1. Stabilizer state breeding

    E-print Network

    Erik Hostens; Jeroen Dehaene; Bart De Moor

    2006-08-18

    We present a breeding protocol that distills pure copies of any stabilizer state from noisy copies and a pool of predistilled pure copies of the same state, by means of local Clifford operations, Pauli measurements and classical communication.

  2. Medial column stabilization.

    PubMed

    Catanzariti, A R

    1991-07-01

    This article presented a brief review of medial column stabilizing procedures. The various types of procedures that have been advocated for different deformities have been discussed. It is important to keep in mind that fusion of any of the medial column joints should not be performed as an isolated procedure in flexible flatfoot deformity. Medial column stabilization is only a component procedure when surgically managing a flexible flatfoot. When choosing procedures to correct a flexible flatfoot, thorough preoperative evaluation is important. It is also important to realize that conservative measures should be exhausted before attempting any type of stabilization of the medial column for flexible flatfoot deformity. Specific criteria for flexible flatfoot surgery should include severe uncontrollable deformity, an inability to wear standard foot gear, and persistent pain and disability despite exhaustive conservative therapy. A medial column stabilization is also an excellent procedure for those patients who have end-stage degenerative joint disease of the medial longitudinal arch. PMID:1893342

  3. Spacecraft stability and control

    NASA Technical Reports Server (NTRS)

    Barret, Chris

    1992-01-01

    The Earth's first artificial satellite, Sputnik 1, slowly tumbled in orbit. The first U.S. satellite, Explorer 1, also tumbled out of control. Today, satellite stability and control has become a higher priority. For a satellite design that is to have a life expectancy of 14 years, appropriate spacecraft flight control systems will be reviewed, stability requirements investigated, and an appropriate flight control system recommended in order to see the design process. Disturbance torques, including aerodynamic, magnetic, gravity gradient, solar, micrometeorite, debris, collision, and internal torques, will be assessed to quantify the disturbance environment so that the required compensating torques can be determined. The control torques, including passive versus active, momentum control, bias momentum, spin stabilization, dual spin, gravity gradient, magnetic, reaction wheels, control moment gyros, inertia augmentation techniques, three-axis control, and reaction control systems (RCSs), will be considered. Conditions for stability will also be considered.

  4. Measuring core stability.

    PubMed

    Liemohn, Wendell P; Baumgartner, Ted A; Gagnon, Laura H

    2005-08-01

    In this study, a 4-item battery of core stability (CS) tests modeled on core stabilization activities used in training and rehabilitation research was developed, and a measurement schedule was established to maximize internal consistency and stability reliabilities. Specifically, we found that 4 test administrations on each of 4 days produced intraclass correlation coefficients that in most instances exceeded 0.90 and stability reliability coefficients on the third and fourth days of testing that exceeded 0.90 for 2 of the tests and 0.80 for the other 2. Thus, it is recommended that in future research, examiners administer the battery for at least 3 days and consider the data collected on day 3 as the best estimate of participant CS. PMID:16095406

  5. Environmental indices in irrigation management.

    PubMed

    Manoliadis, O G

    2001-10-01

    Irrigation management calls for objective criteria capable of representing the economy, reliability, and productivity of irrigation systems. These criteria must be compatible with long-term sustainability and conservation goals. The criteria representing the above goals are the economic effect of management on yield reduction, economic effect, and reliability referring to plant growth and operation of the network. In this study environmental indices are introduced to express the above criteria in quantitative terms. The inclusion of these indices at the farm and network level create a multicriteria framework for decision-making based on composite programming. An experimental study was conducted during the irrigation periods of 1989 and 1990 in Chania, Greece, concerning water delivered to 40 experimental plots, soil moisture content at the rootzone, and irrigation system operational failures. The data collected in real time were used for the calculation of the corresponding environmental indices. The variation in time and space is high and resulted in up to 62% of yield loss and low system performance (up to 7% of system temporal reliability). The study indicated that environmental indices could be incorporated to select alternatives and also to develop policies on water delivery. The final decision involves a trade-off analysis between cost of application and desired system performance. Measures of both primary objectives can be obtained using environmental indices that represent system operation aggregation at its basic levels (on farm and network). PMID:11494068

  6. Energy Efficiency Indicators Methodology Booklet

    SciTech Connect

    Sathaye, Jayant; Price, Lynn; McNeil, Michael; de la rue du Can, Stephane

    2010-05-01

    This Methodology Booklet provides a comprehensive review and methodology guiding principles for constructing energy efficiency indicators, with illustrative examples of application to individual countries. It reviews work done by international agencies and national government in constructing meaningful energy efficiency indicators that help policy makers to assess changes in energy efficiency over time. Building on past OECD experience and best practices, and the knowledge of these countries' institutions, relevant sources of information to construct an energy indicator database are identified. A framework based on levels of hierarchy of indicators -- spanning from aggregate, macro level to disaggregated end-use level metrics -- is presented to help shape the understanding of assessing energy efficiency. In each sector of activity: industry, commercial, residential, agriculture and transport, indicators are presented and recommendations to distinguish the different factors affecting energy use are highlighted. The methodology booklet addresses specifically issues that are relevant to developing indicators where activity is a major factor driving energy demand. A companion spreadsheet tool is available upon request.

  7. Stability of Detached Solidification

    NASA Technical Reports Server (NTRS)

    Mazuruk, K.; Volz, M. P.; Croell, A.

    2009-01-01

    Bridgman crystal growth can be conducted in the so-called "detached" solidification regime, where the growing crystal is detached from the crucible wall. A small gap between the growing crystal and the crucible wall, of the order of 100 micrometers or less, can be maintained during the process. A meniscus is formed at the bottom of the melt between the crystal and crucible wall. Under proper conditions, growth can proceed without collapsing the meniscus. The meniscus shape plays a key role in stabilizing the process. Thermal and other process parameters can also affect the geometrical steady-state stability conditions of solidification. The dynamic stability theory of the shaped crystal growth process has been developed by Tatarchenko. It consists of finding a simplified autonomous set of differential equations for the radius, height, and possibly other process parameters. The problem then reduces to analyzing a system of first order linear differential equations for stability. Here we apply a modified version of this theory for a particular case of detached solidification. Approximate analytical formulas as well as accurate numerical values for the capillary stability coefficients are presented. They display an unexpected singularity as a function of pressure differential. A novel approach to study the thermal field effects on the crystal shape stability has been proposed. In essence, it rectifies the unphysical assumption of the model that utilizes a perturbation of the crystal radius along the axis as being instantaneous. It consists of introducing time delay effects into the mathematical description and leads, in general, to stability over a broader parameter range. We believe that this novel treatment can be advantageously implemented in stability analyses of other crystal growth techniques such as Czochralski and float zone methods.

  8. Soil stabilization 1982

    NASA Astrophysics Data System (ADS)

    Barenberg, E. J.; Thompson, M. R.; Tayabji, S. D.; Nussbaum, P. J.; Ciolko, A. T.

    Seven papers cover the following areas: design, construction and performance of lime, fly ash, and slag pavement; evaluation of heavily loaded cement stabilized bases; coal refuse and fly ash compositions; potential highway base course materials; lime soil mixture design considerations for soils of southeastern United States; short term active soil property changes caused by injection of lime and fly ash; soil cement for use in stream channel grade stabilization structures; and reaction products of lime treated southeastern soils.

  9. Image stabilization system

    NASA Astrophysics Data System (ADS)

    Dahl, S.; Rice, R.

    An image stabilization system is presented to demonstrate an application of a fast steering mirror and a wide angle optical sensor used in closed loop operation. Two parallel optical paths are used, the visual image path for the TV viewer and the IR diode path for the stabilization loop. This operation is very similar to a laser designator type tracker. The demonstration is intended to show the use of modular electro-optic components which are becoming widely used in optical control systems.

  10. Shearing stability of lubricants

    NASA Technical Reports Server (NTRS)

    Shiba, Y.; Gijyutsu, G.

    1984-01-01

    Shearing stabilities of lubricating oils containing a high mol. wt. polymer as a viscosity index improver were studied by use of ultrasound. The oils were degraded by cavitation and the degradation generally followed first order kinetics with the rate of degradation increasing with the intensity of the ultrasonic irradiation and the cumulative energy applied. The shear stability was mainly affected by the mol. wt. of the polymer additive and could be determined in a short time by mechanical shearing with ultrasound.

  11. Stability in dynamical astronomy*

    PubMed Central

    Szebehely, Victor

    1978-01-01

    Hill's concept of stability is generalized and its relation to bifurcation theory is shown. A quantitative measure of stability is introduced that allows the comparison of the stability of different astronomical systems. Theoretical stability limits for triple stellar systems, for planetary systems, and for satellite systems are established. The measure of stability is evaluated for several known triple stellar systems as well as for the planets and for the natural satellites of the solar system. The model of the restricted problem of three bodies and values of the Jacobian constant are used to study planetary and satellite systems. The model of the general problem of three bodies is used to establish criteria for triple stellar systems. In general, the results show a hierarchy of stability: the existing triple systems are more stable than the planetary orbits of the solar system. The satellites of the solar system are least stable; in fact, some of the satellites are close to the line of instability (the Earth's Moon) and some are actually unstable (the four outermost satellites of Jupiter). PMID:16592589

  12. Development and validation of a chromatographic method for determining Clematichinenoside AR and related impurities

    PubMed Central

    2012-01-01

    Background Clematichinenoside AR is a promising lead compound for the treatment of rheumatoid arthritis. A systematic research for the related impurities in AR bulk samples is still lacking. For the safe use of this natural product in future clinical practice, the structure and content of each constituent, including the main ingredient as well as the impurities in AR bulk sample must be characterized in detail. Results A simple and stability indicating RP-HPLC method was developed and validated for determining the purity of clematichinenoside AR (AR), a natural product from the roots of Clematis manshurica Rupr. (Ranunculaceae) with the potential of treating rheumatoid arthritis. Five impurities were characterized, and impurity 2 (Clematomandshurica saponin F) is a new triterpenoid saponin isolated from this product. Optimum separation for clematichinenoside AR and five related impurities was carried out on an Agilent octadecylsilane bonded silica gel column (TC-C18, 4.6 mm ×150 mm, 5 ?m) using a gradient HPLC method. The validation results showed good sensitivity, specificity, linearity(r2>0.9992) precision(RSD<1.63%), accuracy(recoveries in the range of 95.60%-104.76%) and robustness. Three AR bulk samples containing all the impurities were examined by two methods, and the stability of correction factors for the determination of related impurities was discussed. The proposed stability-indicating method was suitable for the quality control of this natural product. Conclusion Five related impurities of clematichinenoside AR were characterized, including a new triterpenoid saponins firstly found in clematichinenoside AR bulk samples. In the simple chromatographic method for determining clematichinenoside AR and its related impurities in bulk samples, the correction factor was better for the quality control in the relative stable concentrations. PMID:23216920

  13. Stability of a new cubic monoxide of Thorium under pressure

    PubMed Central

    Sun, Weiwei; Luo, Wei; Ahuja, Rajeev

    2015-01-01

    Density functional theory has been applied to elucidate the stability of thorium monoxide (ThO). It is found out that the pressure can stabilize the rocksalt phase of ThO, and the transition pressure is estimated between 14 and 22?GPa. The stability of ThO can be attributed due to the gradually filling 5f orbitals at the expense of 7s and 6d electrons in Th metal. For ThO, the pressure induces stronger Th-O bond reflected by the newly established 6d-2p hybridization which is the dominant cause of its stability. The phonon dispersion curves of the rocksalt phase show the positive frequencies which indicates its dynamical stability. Our successful prediction of the stabilization of the metallic ThO has proposed a route to synthesize novel actinide monoxides. PMID:26337015

  14. Stability of a new cubic monoxide of Thorium under pressure.

    PubMed

    Sun, Weiwei; Luo, Wei; Ahuja, Rajeev

    2015-01-01

    Density functional theory has been applied to elucidate the stability of thorium monoxide (ThO). It is found out that the pressure can stabilize the rocksalt phase of ThO, and the transition pressure is estimated between 14 and 22?GPa. The stability of ThO can be attributed due to the gradually filling 5f orbitals at the expense of 7s and 6d electrons in Th metal. For ThO, the pressure induces stronger Th-O bond reflected by the newly established 6d-2p hybridization which is the dominant cause of its stability. The phonon dispersion curves of the rocksalt phase show the positive frequencies which indicates its dynamical stability. Our successful prediction of the stabilization of the metallic ThO has proposed a route to synthesize novel actinide monoxides. PMID:26337015

  15. Council High LevelCouncil High Level IndicatorsIndicators

    E-print Network

    INDICATORS,, ContinuedContinued LifeLife--cycle mortalitycycle mortality ·· Life stage survival estimates accessible.Additional habitat made accessible. Water.Water. ·· Additional water available for fish,Additional water available for fish, anadromousanadromous and resident.and resident. Land.Land. ·· Additional land

  16. Indo-China monsoon indices.

    PubMed

    Tsai, ChinLeong; Behera, Swadhin K; Waseda, Takuji

    2015-01-01

    Myanmar and Thailand often experience severe droughts and floods that cause irreparable damage to the socio-economy condition of both countries. In this study, the Southeastern Asian Summer Monsoon variation is found to be the main element of interannual precipitation variation of the region, more than the El Niño/Southern Oscillation (ENSO). The ENSO influence is evident only during the boreal spring season. Although the monsoon is the major factor, the existing Indian Monsoon Index (IMI) and Western North Pacific Monsoon Index (WNPMI) do not correlate well with the precipitation variation in the study regions of Southern Myanmar and Thailand. Therefore, a new set of indices is developed based on the regional monsoon variations and presented here for the first time. Precipitation variations in Southern Myanmar and Thailand differ as well as the elements affecting the precipitation variations in different seasons. So, separate indices are proposed for each season for Southern Myanmar and Thailand. Four new monsoon indices based on wind anomalies are formulated and are named as the Indochina Monsoon Indices. These new indices correlate better with the precipitation variations of the study region as compared to the existing IMI and WNPMI. PMID:25630503

  17. Indo-China Monsoon Indices

    PubMed Central

    Tsai, ChinLeong; Behera, Swadhin K.; Waseda, Takuji

    2015-01-01

    Myanmar and Thailand often experience severe droughts and floods that cause irreparable damage to the socio-economy condition of both countries. In this study, the Southeastern Asian Summer Monsoon variation is found to be the main element of interannual precipitation variation of the region, more than the El Niño/Southern Oscillation (ENSO). The ENSO influence is evident only during the boreal spring season. Although the monsoon is the major factor, the existing Indian Monsoon Index (IMI) and Western North Pacific Monsoon Index (WNPMI) do not correlate well with the precipitation variation in the study regions of Southern Myanmar and Thailand. Therefore, a new set of indices is developed based on the regional monsoon variations and presented here for the first time. Precipitation variations in Southern Myanmar and Thailand differ as well as the elements affecting the precipitation variations in different seasons. So, separate indices are proposed for each season for Southern Myanmar and Thailand. Four new monsoon indices based on wind anomalies are formulated and are named as the Indochina Monsoon Indices. These new indices correlate better with the precipitation variations of the study region as compared to the existing IMI and WNPMI. PMID:25630503

  18. Gear selector indicator adjustment mechanism

    SciTech Connect

    Kobylarz, L.P.

    1989-04-18

    A motor vehicle automatic transmission gear selector indicator assembly is described which indicates the position of a gear shifter and permits the indicated gear position to be adjusted comprising: a display having gear selector designations and movable means for indicating one of the gear selector designations, and compliant means urging the movable means in one direction, a cable assembly having an outer sheath with first and second mounting means for mounting the opposite ends of the sheath, the cable assembly further having a cable core sliding within the sheath with a first end connected to the display movable means and a second end connected to the gear shifter, wherein tension on the core urges the indicator movable means to move against the compliant means, and an adjustment mechanism including a hollow externally threaded tube with the sheath fixed to the tube with the core passing through the tube, an adjustment wheel having a threaded bore meshing with the external threads of the tube, and a bracket which traps the adjustment wheel, the tube and the bracket including anti-rotation means for preventing rotation of the tube.

  19. Indo-China Monsoon Indices

    NASA Astrophysics Data System (ADS)

    Tsai, Chinleong; Behera, Swadhin K.; Waseda, Takuji

    2015-01-01

    Myanmar and Thailand often experience severe droughts and floods that cause irreparable damage to the socio-economy condition of both countries. In this study, the Southeastern Asian Summer Monsoon variation is found to be the main element of interannual precipitation variation of the region, more than the El Niño/Southern Oscillation (ENSO). The ENSO influence is evident only during the boreal spring season. Although the monsoon is the major factor, the existing Indian Monsoon Index (IMI) and Western North Pacific Monsoon Index (WNPMI) do not correlate well with the precipitation variation in the study regions of Southern Myanmar and Thailand. Therefore, a new set of indices is developed based on the regional monsoon variations and presented here for the first time. Precipitation variations in Southern Myanmar and Thailand differ as well as the elements affecting the precipitation variations in different seasons. So, separate indices are proposed for each season for Southern Myanmar and Thailand. Four new monsoon indices based on wind anomalies are formulated and are named as the Indochina Monsoon Indices. These new indices correlate better with the precipitation variations of the study region as compared to the existing IMI and WNPMI.

  20. Pressure dependent phase stability transformations of GaS: A first principles study

    E-print Network

    Melnik, Roderick

    Pressure dependent phase stability transformations of GaS: A first principles study Bin Wen a principle calculations are used to determine the pressure dependent phase stability transformations for GaS polytypes at pressures up to 1000 GPa. Our results indicate that the relative stability sequence changes

  1. Welfare indicators during broiler slaughtering.

    PubMed

    Grilli, C; Loschi, A R; Rea, S; Stocchi, R; Leoni, L; Conti, F

    2015-01-01

    1. The aim of this study was to identify the most relevant welfare indicators for unloading, lairage, stunning, killing and post-mortem inspection in a poultry slaughter plant. Different indicators were unloading duration, lairage time, environmental variables in the lairage facilities, shackling time and electrical variables used in the water bath. 2. Lairage time did not correlate strongly with dead on arrival. Heat stress was limited by means of ventilation systems, correct cage placement and appropriate stocking density per crate. The acceptable shackling period was about 30 s. 3. The presence of a corneal reflex showed that an animal was alive, while spontaneous wing flapping, spontaneous eye blinking and response to a painful stimulus were regarded as indicators of stunning efficiency. 4. It was concluded that the presence of recent traumatic injuries during the post-mortem inspection could be a valid means to establish whether corrective measures concerning the handling, transport and loading procedures should be taken. PMID:25567419

  2. Flying height stability and spindle motor vibration

    NASA Astrophysics Data System (ADS)

    Ng, Ka Wei; Yuan, Zhimin; Liu, Bo

    2005-05-01

    This paper reports the results of a study on the relationship between slider's dynamic flying height stability and spindle motor vibration. The investigations were carried out with in situ flying height testing technology introduced by the authors. The unbalanced modes, which are the rocking motion of the spindle, were studied in the experiment. Results obtained show that the dynamic stability of slider is a function of the spindle vibration. It is interesting to notice that higher frequency vibration of spindle motor has a greater effect on slider dynamics. Investigations are also extended to characterize the dynamic behavior of the sliders with two types of air-bearing surface (ABS) designs. Results indicate that sliders with higher roll stiffness are of better dynamic performance and flying height stability under the unbalanced modes vibration of spindle motor.

  3. Stability of Intershaft Squeeze Film Dampers

    NASA Technical Reports Server (NTRS)

    El-Shafei, A.

    1991-01-01

    Intershaft squeeze film dampers were investigated for damping of dual rotor aircraft jet engines. It was thought that the intershaft damper would enhance the stability of the rotor-bearing system. Unfortunately, it was determined that the intershaft squeeze film damper was unstable above the engine's first critical speed. Here, a stability analysis of rotors incorporating intershaft squeeze film dampers is discussed. A rotor model consisting of two Jeffcott rotors with two intershaft squeeze film dampers was investigated. Examining the system characteristic equation for the conditions at which the roots indicate an ever-growing unstable motion results in the stability conditions. The cause of the instability is identified as the rotation of the oil in the damper clearance. Several proposed configurations of intershaft squeeze film dampers are discussed, and it is shown that the intershaft dampers are stable supercritically only with a configuration in which the oil film does not rotate.

  4. Extreme temperature indices over Serbia

    NASA Astrophysics Data System (ADS)

    Tosic, I.; Unkasevic, M.

    2012-04-01

    In this work, the extreme climate indices based on the daily maximum and minimum temperatures during the period 1949-2009 at fifteen stations distributed across Serbia were analyzed. The following temperature indices were considered: cold nights (Tn10), cold days (Tx10), warm nights (Tn90), warm days (Tx90) and frost days (FD). The results showed seasonal changes in the minimum and maximum temperature extremes. The most significant trends of temperature indices were revealed for the summer season. According to the seasonal analysis of five temperature extreme indices, it was found that a warming tendency was dominant. Tendencies significant at the 5 % level were obtained during the spring (Tx10) and summer (Tn10, Tn90 and Tx90). The largest warming tendencies of greater than 1 day per decade were found for Tx90 and Tn90 in the summer. A cooling tendency was revealed only during the autumn for Tx10 and FD, suggesting a rise in the number of cold and frost days. An analysis of the extreme temperature indices suggested that the Serbian climate generally tended to become warmer in the last 61 years. To describe the link of the extreme temperature indices with the large-scale atmospheric circulations, indexes of teleconnection patterns, such as the North Atlantic Oscillation (NAO), East Atlantic (EA) and East Atlantic/West Russia (EA-WR) were investigated. It was found that the Tn90 and Tx90 values were highly positively correlated with the EA index during the winter, spring and summer, while Tx10 and Tn10 values were negatively correlated. The Tn10 value probably decreased because of the trend to more positive phases of the EA. Opposite correlations with the EA-WR were found for the Tn10 and Tn90 values in the autumn.

  5. Uncertainties in climate stabilization

    SciTech Connect

    Wigley, T. M.; Clarke, Leon E.; Edmonds, James A.; Jacoby, H. D.; Paltsev, S.; Pitcher, Hugh M.; Reilly, J. M.; Richels, Richard G.; Sarofim, M. C.; Smith, Steven J.

    2009-11-01

    We explore the atmospheric composition, temperature and sea level implications of new reference and cost-optimized stabilization emissions scenarios produced using three different Integrated Assessment (IA) models for U.S. Climate Change Science Program (CCSP) Synthesis and Assessment Product 2.1a. We also consider an extension of one of these sets of scenarios out to 2300. Stabilization is defined in terms of radiative forcing targets for the sum of gases potentially controlled under the Kyoto Protocol. For the most stringent stabilization case (“Level 1” with CO2 concentration stabilizing at about 450 ppm), peak CO2 emissions occur close to today, implying a need for immediate CO2 emissions abatement if we wish to stabilize at this level. In the extended reference case, CO2 stabilizes at 1000 ppm in 2200 – but even to achieve this target requires large and rapid CO2 emissions reductions over the 22nd century. Future temperature changes for the Level 1 stabilization case show considerable uncertainty even when a common set of climate model parameters is used (a result of different assumptions for non-Kyoto gases). Uncertainties are about a factor of three when climate sensitivity uncertainties are accounted for. We estimate the probability that warming from pre-industrial times will be less than 2oC to be about 50%. For one of the IA models, warming in the Level 1 case is greater out to 2050 than in the reference case, due to the effect of decreasing SO2 emissions that occur as a side effect of the policy-driven reduction in CO2 emissions. Sea level rise uncertainties for the Level 1 case are very large, with increases ranging from 12 to 100 cm over 2000 to 2300.

  6. America's Children: Key National Indicators

    E-print Network

    Rau, Don C.

    Development http://www.nichd.nih.gov Maternal and Child Health Bureau http://www.mchb.hrsa.gov National CenterAmerica's Children: Key National Indicators of Well-Being, 2013 Federal Interagency Forum on Child Interagency Forum on Child and Family Statistics #12;Federal Interagency Forum on Child and Family Statistics

  7. Developing Indicators of Student Coursework.

    ERIC Educational Resources Information Center

    McDonnell, Lorraine M.; Ormseth, Tor

    The School Reform Assessment (SRA) project began in 1987 with the objective of developing indicators of student coursework that reliably and validly measure this central feature of schooling, while remaining sensitive to major policy changes and the information needs of policymakers, and efficiently collecting and reporting data. This paper…

  8. Can biological indicators predict the

    E-print Network

    Cai, Long

    /TAXI/GETTY Psychiatry has long been a second-class citizen in science and medicine. Despite much effort, the causes biomarkers into psychiatry (Fig. 1), and there is hope that such biological indicators will improve, there has been little discussion of the social, ethical and legal problems posed by their use in psychiatry

  9. Proximity Indicator for Remote Manipulator

    NASA Technical Reports Server (NTRS)

    Bejczy, A. K.

    1985-01-01

    Display indicates pitch, yaw, and distance of remote manipulator with respect to object to be grasped. Displays numerical values and bargraph simulation of position and orientation of hand. When errors in position and orientation are small enough to ensure successful grasp, unit alerts operator with audible and visible signals.

  10. Social Indicators and Social Reporting

    ERIC Educational Resources Information Center

    Parke, Robert; Seidman, David

    1978-01-01

    Describes the several research traditions which combine to form the social indicators movement. All the traditions share concern for measurement, analysis, and reporting of aspects of social conditions to a general audience. Journal available from: American Academy of Political and Social Science, 3937 Chestnut Street, Philadelphia, Pennsylvania…

  11. Scale-Independent Bibliometric Indicators

    ERIC Educational Resources Information Center

    Katz, J. Sylvan

    2005-01-01

    This article presents the author's critique of Anthony F. J. van Raan's article titled, "Measurement of Central Aspects of Scientific Research: Performance, Interdisciplinarity, Structure." van Raan makes an excellent case for using bibliometric data to measure some central aspects of scientific research and to construct indicators of groups:…

  12. College Readiness Indicator Systems Framework

    ERIC Educational Resources Information Center

    Borsato, Graciela N.; Nagaoka, Jenny; Folley, Ellen

    2013-01-01

    A new framework from the CRIS initiative provides guidance for schools and districts to implement a system of indicators and supports for students who are off track for post-secondary success. The CRIS framework is intended as a tool to help districts and schools implement the conditions, processes, and supports needed to increase the number of…

  13. MSPI False Indication Probability Simulations

    SciTech Connect

    Dana Kelly; Kurt Vedros; Robert Youngblood

    2011-03-01

    This paper examines false indication probabilities in the context of the Mitigating System Performance Index (MSPI), in order to investigate the pros and cons of different approaches to resolving two coupled issues: (1) sensitivity to the prior distribution used in calculating the Bayesian-corrected unreliability contribution to the MSPI, and (2) whether (in a particular plant configuration) to model the fuel oil transfer pump (FOTP) as a separate component, or integrally to its emergency diesel generator (EDG). False indication probabilities were calculated for the following situations: (1) all component reliability parameters at their baseline values, so that the true indication is green, meaning that an indication of white or above would be false positive; (2) one or more components degraded to the extent that the true indication would be (mid) white, and “false” would be green (negative) or yellow (negative) or red (negative). In key respects, this was the approach taken in NUREG-1753. The prior distributions examined were the constrained noninformative (CNI) prior used currently by the MSPI, a mixture of conjugate priors, the Jeffreys noninformative prior, a nonconjugate log(istic)-normal prior, and the minimally informative prior investigated in (Kelly et al., 2010). The mid-white performance state was set at ?CDF = ?10 ? 10-6/yr. For each simulated time history, a check is made of whether the calculated ?CDF is above or below 10-6/yr. If the parameters were at their baseline values, and ?CDF > 10-6/yr, this is counted as a false positive. Conversely, if one or all of the parameters are set to values corresponding to ?CDF > 10-6/yr but that time history’s ?CDF < 10-6/yr, this is counted as a false negative indication. The false indication (positive or negative) probability is then estimated as the number of false positive or negative counts divided by the number of time histories (100,000). Results are presented for a set of base case parameter values, and three sensitivity cases in which the number of FOTP demands was reduced, along with the Birnbaum importance of the FOTP.

  14. Backcrossing to increase meiotic stability in triticale.

    PubMed

    Giacomin, R M; Assis, R; Brammer, S P; Nascimento Junior, A; Da-Silva, P R

    2015-01-01

    Triticale (X Triticosecale Wittmack) is an intergeneric hybrid derived from a cross between wheat and rye. As a newly created allopolyploid, the plant shows instabilities during the meiotic process, which may result in the loss of fertility. This genomic instability has hindered the success of triticale-breeding programs. Therefore, strategies should be developed to obtain stable triticale lines for use in breeding. In some species, backcrossing has been effective in increasing the meiotic stability of lineages. To assess whether backcrossing has the same effect in triticale, indices of meiotic abnormalities, meiotic index, and pollen viability were determined in genotypes from multiple generations of triticale (P1, P2, F1, F2, BC1a, and BC1b). All analyzed genotypes exhibited instability during meiosis, and their meiotic index values were all lower than normal. However, the backcrosses BC1a and BC1b showed the lowest mean meiotic abnormalities and the highest meiotic indices, demonstrating higher stability. All genotypes showed a high rate of pollen viability, with the backcrosses BC1a and BC1b again exhibiting the best values. Statistical analyses confirmed that backcrossing positively affects the meiotic stability of triticale. Our results show that backcrossing should be considered by breeders aiming to obtain triticale lines with improved genomic stability. PMID:26400358

  15. Thermodynamic modeling of natural zeolite stability

    SciTech Connect

    Chipera, S.J.; Bish, D.L.

    1997-06-01

    Zeolites occur in a variety of geologic environments and are used in numerous agricultural, commercial, and environmental applications. It is desirable to understand their stability both to predict future stability and to evaluate the geochemical conditions resulting in their formation. The use of estimated thermodynamic data for measured zeolite compositions allows thermodynamic modeling of stability relationships among zeolites in different geologic environments (diagenetic, saline and alkaline lakes, acid rock hydrothermal, basic rock, deep sea sediments). This modeling shows that the relative cation abundances in both the aqueous and solid phases, the aqueous silica activity, and temperature are important factors in determining the stable zeolite species. Siliceous zeolites (e.g., clinoptilolite, mordenite, erionite) present in saline and alkaline lakes or diagenetic deposits formed at elevated silica activities. Aluminous zeolites (e.g., natrolite, mesolite/scolecite, thomsonite) formed in basic rocks in association with reduced silica activities. Likewise, phillipsite formation is favored by reduced aqueous silica activities. The presence of erionite, chabazite, and phillipsite are indicative of environments with elevated potassium concentrations. Elevated temperature, calcic water conditions, and reduced silica activity help to enhance the laumontite and wairakite stability fields. Analcime stability increases with increased temperature and aqueous Na concentration, and/or with decreased silica activity.

  16. ICRF stabilization of sawteeth on TFTR

    SciTech Connect

    Phillips, C.K.; Hosea, J.; Stevens, J.; Wilson, J.R.; Bell, M.; Bitter, M.; Cheng, C.Z.; Darrow, D.; Fredrickson, E.; Hammett, G.W.; Hill, K.; Hsuan, H.; Jassby, D.; McCune, D.; McGuire, K.; Owens, D.K.; Park, H.; Ramsey, A.; Schilling, G.; Schivell, J.; Stratton, B.; Synakowski, E.; Taylor, G.; Towner, H.; White, R.; Zweben, S. . Plasma Physics Lab.); Marmar, E.; Snipes, J.; Terry, J.; Bo

    1992-01-01

    Results obtained from experiments utilizing high power ICRF (ion cyclotron range of frequency) heating to stabilize sawtooth oscillations on TFTR are reviewed. The key observations include existence of a minimum ICRF power required to achieve stabilization, a dependence of the stabilization threshold on the relative size of the ICRF power deposition profile to the q=1 volume, and a peaking of the equilibrium pressure and current profiles during sawtooth-free phases of the discharges. In addition, preliminary measurements of the poloidal magnetic field profile indicate that q on axis decreases to a value of 0.55{plus minus}0.15 after a sawtooth-stabilized period of {approximately}0.5 sec has transpired. The results are discussed in the context of theory, which suggests that the fast ions produced by the ICRF heating suppress sawteeth by stabilizing the m=1 MHD instabilities believed to be the trigger for the sawtooth oscillations. Though qualitative agreement is found between the observations and the theory, further refinement of the theory coupled with more accurate measurements of experimental profiles will be required in order to complete quantitative comparisons.

  17. ICRF stabilization of sawteeth on TFTR

    SciTech Connect

    Phillips, C.K.; Hosea, J.; Stevens, J.; Wilson, J.R.; Bell, M.; Bitter, M.; Cheng, C.Z.; Darrow, D.; Fredrickson, E.; Hammett, G.W.; Hill, K.; Hsuan, H.; Jassby, D.; McCune, D.; McGuire, K.; Owens, D.K.; Park, H.; Ramsey, A.; Schilling, G.; Schivell, J.; Stratton, B.; Synakowski, E.; Taylor, G.; Towner, H.; White, R.; Zweben, S.; Marmar, E.; Snipes, J.; Terry, J.; Boivin, R.; Phillips, M.W.; Hughes, M.; Bush, C.; Goldfinger, R.; Hoffman, D.; Houlberg, W.; Nagayama, Y.; Smithe, D.N.

    1992-01-01

    Results obtained from experiments utilizing high power ICRF (ion cyclotron range of frequency) heating to stabilize sawtooth oscillations on TFTR are reviewed. The key observations include existence of a minimum ICRF power required to achieve stabilization, a dependence of the stabilization threshold on the relative size of the ICRF power deposition profile to the q=1 volume, and a peaking of the equilibrium pressure and current profiles during sawtooth-free phases of the discharges. In addition, preliminary measurements of the poloidal magnetic field profile indicate that q on axis decreases to a value of 0.55{plus_minus}0.15 after a sawtooth-stabilized period of {approximately}0.5 sec has transpired. The results are discussed in the context of theory, which suggests that the fast ions produced by the ICRF heating suppress sawteeth by stabilizing the m=1 MHD instabilities believed to be the trigger for the sawtooth oscillations. Though qualitative agreement is found between the observations and the theory, further refinement of the theory coupled with more accurate measurements of experimental profiles will be required in order to complete quantitative comparisons.

  18. Stability of Lobed Balloons

    NASA Technical Reports Server (NTRS)

    Ball, Danny (Technical Monitor); Pagitz, M.; Pellegrino, Xu S.

    2004-01-01

    This paper presents a computational study of the stability of simple lobed balloon structures. Two approaches are presented, one based on a wrinkled material model and one based on a variable Poisson s ratio model that eliminates compressive stresses iteratively. The first approach is used to investigate the stability of both a single isotensoid and a stack of four isotensoids, for perturbations of in.nitesimally small amplitude. It is found that both structures are stable for global deformation modes, but unstable for local modes at su.ciently large pressure. Both structures are stable if an isotropic model is assumed. The second approach is used to investigate the stability of the isotensoid stack for large shape perturbations, taking into account contact between di.erent surfaces. For this structure a distorted, stable configuration is found. It is also found that the volume enclosed by this con.guration is smaller than that enclosed by the undistorted structure.

  19. Generalized Lotka stability.

    PubMed

    Smith, J D H; Zhang, C

    2015-08-01

    The recently developed macroscopic approach to demography describes the age distribution of mothers and the net maternity function for a given human population entirely in terms of five parameters. Tracking of these parameters provides a number of new tools for analyzing populations and predicting their future states. Within the macroscopic approach, the new concept of generalized Lotka stability is presented in this paper, as an extension of a strong version of classic Lotka stability. The two leading parameters of the macroscopic approach, the Malthusian parameter r and the perturbation s, are computed from population data and plotted in two-dimensional parameter space. Generalized Lotka stability is then defined in terms of the movement of the (r,s)-vector over time. It may be observed in a number of human populations at specific periods of their history. PMID:25998604

  20. Jet Fuel Thermal Stability

    NASA Technical Reports Server (NTRS)

    Taylor, W. F. (editor)

    1979-01-01

    Various aspects of the thermal stability problem associated with the use of broadened-specification and nonpetroleum-derived turbine fuels are addressed. The state of the art is reviewed and the status of the research being conducted at various laboratories is presented. Discussions among representatives from universities, refineries, engine and airframe manufacturers, airlines, the Government, and others are presented along with conclusions and both broad and specific recommendations for future stability research and development. It is concluded that significant additional effort is required to cope with the fuel stability problems which will be associated with the potentially poorer quality fuels of the future such as broadened specification petroleum fuels or fuels produced from synthetic sources.

  1. 14 CFR 23.181 - Dynamic stability.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 false Dynamic stability. 23.181...Stability § 23.181 Dynamic stability. Link...stability augmentation system, reference § 23...acceptability of that system. (d) During...follows: § 23.181 Dynamic stability....

  2. Stabilized PV system

    DOEpatents

    Dinwoodie, Thomas L. (Piedmont, CA)

    2002-12-17

    A stabilized PV system comprises an array of photovoltaic (PV) assemblies mounted to a support surface. Each PV assembly comprises a PV module and a support assembly securing the PV module to a position overlying the support surface. The array of modules is circumscribed by a continuous, belt-like perimeter assembly. Cross strapping, extending above, below or through the array, or some combination of above, below and through the array, secures a first position along the perimeter assembly to at least a second position along the perimeter assembly thereby stabilizing the array against wind uplift forces. The first and second positions may be on opposite sides on the array.

  3. Stability of loess

    USGS Publications Warehouse

    Lutenegger, A.J.; Hallberg, G.R.

    1988-01-01

    Lutenegger, A.J. and Hallberg, G.R., 1988. Stability of loess. Eng. Geol., 25: 247-261. The natural stability of loess soils can be related to fundamental geotechnical properties such as Atterberg limits, water content and void ratio. Field observations of unstable conditions in loess deposits in the upper midwest, U.S.A. show relationships between instability and the in situ moisture content and the liquidity index of the loess. Unstable loess can attain natural moisture contents equal to, or greater than, its liquid limit. Implications of these observations for applied engineering works are described. ?? 1988.

  4. Stability of regional configurations

    SciTech Connect

    Canavan, G.H.

    1998-08-13

    At moderate force levels the first strike stability index is proportional to the first strike cost, so as the attacker minimizes attack costs, he automatically minimizes stability. Weapons grow rapidly and saturate to levels comparable to the number of value targets held at risk. This growth could appear destabilizing to dominant regional powers, whose response could in turn appear threatening to the major nuclear powers, which could slow or halt efforts towards deep reductions. The fundamental way to alter these pressures appears to be through reducing the likelihood of regional crises by removing these fundamental antagonisms.

  5. Stabilized Zeeman split laser

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The development of a stablized Zeeman split laser for use in a polarization profilometer is discussed. A Hewlett-Packard laser was modified to stabilize the Zeeman split beat frequency thereby increasing the phase measurement accuracy from the Hewlett-Packard 3 degrees to an accuracy of .01 degrees. The addition of a two layered inductive winding converts the laser to a current controlled oscillator whose frequency is linearly related to coil current. This linear relationship between coil current and laser frequency permits phase locking the laser frequency to a stable crystal controlled reference frequency. The stability of the system is examined and the equipment operation procedures are outlined.

  6. Stability criteria for emulsions

    NASA Astrophysics Data System (ADS)

    Bibette, J.; Morse, D. C.; Witten, T. A.; Weitz, D. A.

    1992-10-01

    The coalescence of monodisperse silicone oil-in-water emulsions stabilized with sodium dodecyl sulfate has been studied. We report the existence of a sharp destabilization threshold, controlled by surfactant chemical potential, osmotic pressure, and droplet diameter, at which the rate of coalescence increases dramatically. We present evidence that the stability of the emulsions can be characterized by two microscopic parameters: a minimum stable value of the surfactant chemical potential and a maximum value of the pressure exerted upon a droplet-droplet interface.

  7. Covariance propagation in spectral indices

    DOE PAGESBeta

    Griffin, P. J.

    2015-01-09

    The dosimetry community has a history of using spectral indices to support neutron spectrum characterization and cross section validation efforts. An important aspect to this type of analysis is the proper consideration of the contribution of the spectrum uncertainty to the total uncertainty in calculated spectral indices (SIs). This study identifies deficiencies in the traditional treatment of the SI uncertainty, provides simple bounds to the spectral component in the SI uncertainty estimates, verifies that these estimates are reflected in actual applications, details a methodology that rigorously captures the spectral contribution to the uncertainty in the SI, and provides quantified examplesmore »that demonstrate the importance of the proper treatment the spectral contribution to the uncertainty in the SI.« less

  8. Chapter A7. Biological Indicators

    USGS Publications Warehouse

    Myers, Donna N.; Wilde, Franceska D.

    2003-01-01

    The National Field Manual for the Collection of Water-Quality Data (National Field Manual) provides guidelines and standard procedures for U.S. Geological Survey (USGS) personnel who collect data used to assess the quality of the Nation's surface-water and ground-water resources. This chapter of the manual includes procedures for the (1) determination of biochemical oxygen demand using a 5-day bioassay test; (2) collection, identification, and enumeration of fecal indicator bacteria; (3) collection of samples and information on two laboratory methods for fecal indicator viruses (coliphages); and (4) collection of samples for protozoan pathogens. Each chapter of the National Field Manual is published separately and revised periodically. Newly published and revised chapters are posted on the World Wide Web on the USGS page 'National Field Manual for the Collection of Water-Quality Data.' The URL for this page is http://pubs.water.usgs.gov/twri9A/ (accessed November 25, 2003).

  9. Covariance propagation in spectral indices

    SciTech Connect

    Griffin, P. J.

    2015-01-09

    The dosimetry community has a history of using spectral indices to support neutron spectrum characterization and cross section validation efforts. An important aspect to this type of analysis is the proper consideration of the contribution of the spectrum uncertainty to the total uncertainty in calculated spectral indices (SIs). This study identifies deficiencies in the traditional treatment of the SI uncertainty, provides simple bounds to the spectral component in the SI uncertainty estimates, verifies that these estimates are reflected in actual applications, details a methodology that rigorously captures the spectral contribution to the uncertainty in the SI, and provides quantified examples that demonstrate the importance of the proper treatment the spectral contribution to the uncertainty in the SI.

  10. Thermodynamic indicators for environmental certification.

    PubMed

    Panzieri, Margherita; Porcelli, Marcello; Pulselli, Federico Maria

    2002-09-01

    The Earth is an open thermodynamic system, that remains in a steady state far from the equilibrium, through energy and matter exchanges with the surrounding environment. These natural constraints, which prevent the system from maximizing its entropy, are threatened by human action and our ecosystem needs urgent protection. In this viewpoint the environmental certification was born, according to international standards ISO 14001, ISO 14040, and European Regulation EMAS. These are voluntary adhesions to a program of environmental protection by companies, administrations and organizations which, starting from the respect of the existing environmental laws and regulations, decide to further improve their environmental performance. To obtain and maintain certification of a system is necessary to apply some indicators to evaluate its environmental performance and to demonstrate its progressive improvement. Here we propose to use for this purpose the thermodynamic indicators produced from energy analysis by Odum. The case study is Montalcino city (Italy) and energy indicators are used to evaluate environmental performance of this system where exist different activities, from agricultural productions, to tourism. Results show that energy analysis could become a valid standard monitoring method for environmental certification, especially in consideration of its wide application field. PMID:12407910

  11. DOE performance indicators guidance document

    SciTech Connect

    Not Available

    1992-12-01

    SEN-29-91 directed that a Department-wide uniform process for trending and analysis of operational data be established for DOE facilities. This Performance Indicator (PI) Program establishes a uniform system for trending and analyzing operational data providing an important tool to help assess and support progress in improving performance and strengthening both DOE and contractor line management control of operations. DOE, similar to the commercial nuclear industry, considers that facilities with good performance, as measured by an overall set of performance indicators, are well-managed facilities. The Performance Indicator Program established by SEN-29-91 is but one of several initiatives undertaken by DOE to instill a new DOE and DOE contractor line management culture committed to achieving a rising standard of acceptable performance. Line management trending and analysis of data depicting the performance of their facilities is an essential element in creating this culture of ``continuous improvement,`` where performance gains achieved are maintained and early identification of deteriorating environmental, safety, and health conditions is accomplished.

  12. Indications for eye removal surgeries

    PubMed Central

    Koylu, Mehmet T.; Gokce, Gokcen; Uysal, Yusuf; Ceylan, Osman M.; Ak?nc?oglu, Dorukcan; Gunal, Armagan

    2015-01-01

    Objectives: To analyze the indications and types of eye removals at a military tertiary care hospital in Turkey. Methods: The medical records (age, gender, affected eye, type of surgical procedure, indications of surgery) of 123 patients who underwent evisceration and enucleation in the course of a 15-year period (January 2000 to December 2014) at Gulhane Military Medical Academy, Ankara, Turkey were reviewed retrospectively. Results: The mean age was 35.61±18.52 (range 3-80 years). The number of male in the patient group was 92 (74.8%) and female was 31 (25.2%). Patients who underwent evisceration were 95 (77.2%), whereas 28 (22.8%) of them underwent enucleation. The mean age of the eviscerated patients was 30.63±13.08, whereas the mean age of the enucleated patients was 52.50±23.92 (p<0.001). The leading indications for eye amputations were trauma (n=62, 50.4%), malignancy (n=20, 16.3%), painful blind eye and absolute glaucoma (n=20, 16.3%), endophthalmitis (n=12, 9.7%), and phthisis bulbi, and cosmetic reasons (n=9, 7.3%). Conclusion: Trauma was the most common etiology for evisceration, and malignancy was the most common etiology for enucleation. Using protective eyewear and early detection of intraocular malignancy and glaucoma through routine ophthalmic examinations are essential for providing non-invasive treatment modalities instead of eye removal. PMID:26446332

  13. Stability and noise in biochemical switches

    E-print Network

    William Bialek

    2000-05-15

    Many processes in biology, from the regulation of gene expression in bacteria to memory in the brain, involve switches constructed from networks of biochemical reactions. Crucial molecules are present in small numbers, raising questions about noise and stability. Analysis of noise in simple reaction schemes indicates that switches stable for years and switchable in milliseconds can be built from fewer than one hundred molecules. Prospects for direct tests of this prediction, as well as implications, are discussed.

  14. Indices of 1-forms, intersection indices, and Newton polyhedra

    NASA Astrophysics Data System (ADS)

    Esterov, A. I.

    2006-08-01

    The intersection indices of a certain kind of analytic set (resultant cycles) are expressed in terms of the Newton polyhedra of the corresponding defining systems of functions, provided that the principal parts of the functions are in general position. Among special cases of resultant cycles are complete intersections and the loci of matrix rank drop. Among special cases of the intersection indices of such sets are the index of a singularity of a Poincaré-Hopf vector field and its generalizations to the case of singular varieties, the index of a system of germs of 1-forms at an isolated singularity of a Gusein-Zade-Ebeling complete intersection, and the Suwa residue of a system of germs of sections of a vector bundle. One also obtains as a consequence the well-known Kushnirenko-Oka formula for the Milnor number of the germ of a map in terms of the Newton polyhedra of its components. A generalization of the well-known equality of the above-mentioned invariants of singularities to the dimensions of certain local rings is also presented.

  15. ENVIRONMENTAL EVALUATION FOR UTILIZATION OF ASH IN SOIL STABILIZATION

    SciTech Connect

    David J. Hassett; Loreal V. Heebink

    2001-08-01

    The Minnesota Pollution Control Agency (MPCA) approved the use of coal ash in soil stabilization, indicating that environmental data needed to be generated. The overall project goal is to evaluate the potential for release of constituents into the environment from ash used in soil stabilization projects. Supporting objectives are: (1) To ensure sample integrity through implementation of a sample collection, preservation, and storage protocol to avoid analyte concentration or loss. (2) To evaluate the potential of each component (ash, soil, water) of the stabilized soil to contribute to environmental release of analytes of interest. (3) To use laboratory leaching methods to evaluate the potential for release of constituents to the environment. (4) To facilitate collection of and to evaluate samples from a field runoff demonstration effort. The results of this study indicated limited mobility of the coal combustion fly ash constituents in laboratory tests and the field runoff samples. The results presented support previous work showing little to negligible impact on water quality. This and past work indicates that soil stabilization is an environmentally beneficial CCB utilization application as encouraged by the U.S. Environmental Protection Agency. This project addressed the regulatory-driven environmental aspect of fly ash use for soil stabilization, but the demonstrated engineering performance and economic advantages also indicate that the use of CCBs in soil stabilization can and should become an accepted engineering option.

  16. Diodes stabilize LED output

    NASA Technical Reports Server (NTRS)

    Deters, R. A.

    1977-01-01

    Small-signal diodes are placed in series with light-emitting diodes (LED's) to stabilize LED output against temperature fluctuations. Simple inexpensive method compensates for thermal fluctuations over a broad temperature range. Requiring few components, technique is particularly useful where circuit-board space is limited.

  17. Commentaries Stability and change

    E-print Network

    Todd, James T.

    Commentaries Stability and change James Todd Department of Psychology, Ohio State University properties to define ``shape equivalence'', it is possible to create a hierarchy of # 2005 Psychology Press, 2005, 12 (4), 639±690 #12;geometries (i.e., Euclidean, affine, conformal, etc.) in which structural

  18. Sprinkler Bifurcations and Stability

    ERIC Educational Resources Information Center

    Sorensen, Jody; Rykken, Elyn

    2010-01-01

    After discussing common bifurcations of a one-parameter family of single variable functions, we introduce sprinkler bifurcations, in which any number of new fixed points emanate from a single point. Based on observations of these and other bifurcations, we then prove a number of general results about the stabilities of fixed points near a…

  19. Waste Stabilization Ponds.

    ERIC Educational Resources Information Center

    Koundakjian, Philip

    This self-paced course contains reading assignments from a waste stabilization ponds operating manual, supportive text, example problems, and review questions, and a final examination. The course covers calculation of pond surface area, pond volume, organic load, detention time, drawdown, storage capacity, efficiency, and discharge. In addition,…

  20. Orbit Stabilization of Nanosat

    SciTech Connect

    JOHNSON,DAVID J.

    1999-12-01

    An algorithm is developed to control a pulsed {Delta}V thruster on a small satellite to allow it to fly in formation with a host satellite undergoing time dependent atmospheric drag deceleration. The algorithm uses four short thrusts per orbit to correct for differences in the average radii of the satellites due to differences in drag and one thrust to symmetrize the orbits. The radial difference between the orbits is the only input to the algorithm. The algorithm automatically stabilizes the orbits after ejection and includes provisions to allow azimuthal positional changes by modifying the drag compensation pulses. The algorithm gives radial and azimuthal deadbands of 50 cm and 3 m for a radial measurement accuracy of {+-} 5 cm and {+-} 60% period variation in the drag coefficient of the host. Approaches to further reduce the deadbands are described. The methodology of establishing a stable orbit after ejection is illustrated in an appendix. The results show the optimum ejection angle to minimize stabilization thrust is upward at 86{sup o} from the orbital velocity. At this angle the stabilization velocity that must be supplied by the thruster is half the ejection velocity. An ejection velocity of 0.02 m/sat 86{sup o} gives an azimuthal separation after ejection and orbit stabilization of 187 m. A description of liquid based gas thrusters suitable for the satellite control is included in an appendix.

  1. Nanostructures for enzyme stabilization

    SciTech Connect

    Kim, Jungbae; Grate, Jay W.; Wang, Ping

    2006-02-02

    The last decade has witnessed notable breakthroughs in nanotechnology with development of various nanostructured materials such as mesoporous materials and nanoparticles. These nanostructures have been used as a host for enzyme immobilization via various approaches, such as enzyme adsorption, covalent attachment, enzyme encapsulation, and sophisticated combinations of methods. This review discusses the stabilization mechanisms behind these diverse approaches; such as confinement, pore size and volume, charge interaction, hydrophobic interaction, and multipoint attachment. In addition, we will introduce recent rigorous approaches to improve the enzyme stability in these nanostructures or develop new nanostructures for the enzyme stabilization. Especially, we will introduce our recent invention of a nanostructure, called single enzyme nanoparticles (SENs). In the form of SENs, each enzyme molecule is surrounded with a nanometer scale network, resulting in stabilization of enzyme activity without any serious limitation for the substrate transfer from solution to the active site. SENs can be further immobilized into mesoporous silica with a large surface area, providing a hierarchical approach for stable, immobilized enzyme systems for various applications, such as bioconversion, bioremediation, and biosensors.

  2. Stabilized chromium oxide film

    DOEpatents

    Nyaiesh, A.R.; Garwin, E.L.

    1986-08-04

    Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150A are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.

  3. Stabilized chromium oxide film

    DOEpatents

    Garwin, Edward L. (Los Altos, CA); Nyaiesh, Ali R. (Palo Alto, CA)

    1988-01-01

    Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150.ANG. are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.

  4. STORMWATER MANAGEMENT MEASURES AND FECAL INDICATOR BACTERIA

    E-print Network

    STORMWATER MANAGEMENT MEASURES AND FECAL INDICATOR BACTERIA BY ROBERT A. WILDEY BA, New College............................................................................................................. 1 Regulatory Limits for Indicator Bacteria................................................................ 2 Indicator Bacteria in the Environment

  5. Construction and demolition waste indicators.

    PubMed

    Mália, Miguel; de Brito, Jorge; Pinheiro, Manuel Duarte; Bravo, Miguel

    2013-03-01

    The construction industry is one of the biggest and most active sectors of the European Union (EU), consuming more raw materials and energy than any other economic activity. Furthermore, construction waste is the commonest waste produced in the EU. Current EU legislation sets out to implement construction and demolition waste (CDW) prevention and recycling measures. However it lacks tools to accelerate the development of a sector as bound by tradition as the building industry. The main objective of the present study was to determine indicators to estimate the amount of CDW generated on site both globally and by waste stream. CDW generation was estimated for six specific sectors: new residential construction, new non-residential construction, residential demolition, non-residential demolition, residential refurbishment, and non-residential refurbishment. The data needed to develop the indicators was collected through an exhaustive survey of previous international studies. The indicators determined suggest that the average composition of waste generated on site is mostly concrete and ceramic materials. Specifically for new residential and new non-residential construction the production of concrete waste in buildings with a reinforced concrete structure lies between 17.8 and 32.9 kg m(-2) and between 18.3 and 40.1 kg m(-2), respectively. For the residential and non-residential demolition sectors the production of this waste stream in buildings with a reinforced concrete structure varies from 492 to 840 kg m(-2) and from 401 to 768 kg/m(-2), respectively. For the residential and non-residential refurbishment sectors the production of concrete waste in buildings lies between 18.9 and 45.9 kg/m(-2) and between 18.9 and 191.2 kg/m(-2), respectively. PMID:23315370

  6. Axisymmetric annular curtain stability

    NASA Astrophysics Data System (ADS)

    Ahmed, Zahir U.; Khayat, Roger E.; Maissa, Philippe; Mathis, Christian

    2012-06-01

    A temporal stability analysis was carried out to investigate the stability of an axially moving viscous annular liquid jet subject to axisymmetric disturbances in surrounding co-flowing viscous gas media. We investigated in this study the effects of inertia, surface tension, the gas-to-liquid density ratio, the inner-to-outer radius ratio and the gas-to-liquid viscosity ratio on the stability of the jet. With an increase in inertia, the growth rate of the unstable disturbances is found to increase. The dominant (or most unstable) wavenumber decreases with increasing Reynolds number for larger values of the gas-to-liquid viscosity ratio. However, an opposite tendency for the most unstable wavenumber is predicted for small viscosity ratio in the same inertia range. The surrounding gas density, in the presence of viscosity, always reduces the growth rate, hence stabilizing the flow. There exists a critical value of the density ratio above which the flow becomes stable for very small viscosity ratio, whereas for large viscosity ratio, no stable flow appears in the same range of the density ratio. The curvature has a significant destabilizing effect on the thin annular jet, whereas for a relatively thick jet, the maximum growth rate decreases as the inner radius increases, irrespective of the surrounding gas viscosity. The degree of instability increases with Weber number for a relatively large viscosity ratio. In contrast, for small viscosity ratio, the growth rate exhibits a dramatic dependence on the surface tension. There is a small Weber number range, which depends on the viscosity ratio, where the flow is stable. The viscosity ratio always stabilizes the flow. However, the dominant wavenumber increases with increasing viscosity ratio. The range of unstable wavenumbers is affected only by the curvature effect.

  7. Autographic Indicator for Tension Tests

    E-print Network

    Hood, George J.

    1902-01-01

    . The first class containing devices which have parts of the record* ing device fixed to some part of the testing machine of discon­ nected entirely* She second class, including all recording devices connected only to the test piece* The first class... is inaccurate because distortions in the frame of the testing machine itself9 enter into the autographic record* Examples of the first class may be found in •Handbook of Testing Materials9 by Adolf Martens, two volumes* In the second class, the indicators...

  8. Space Weathering: An Ultraviolet Indicator

    NASA Technical Reports Server (NTRS)

    Hendrix, A. R.; Vilas, F.

    2004-01-01

    We present evidence suggesting that the spectral slope of airless bodies in the UV-visible wavelength range can be used as an indicator of exposure to space weathering. While space weathering generally produces a reddening of spectra in the visible-NIR spectral regions, it tends to result in a bluing of the UV-visible portion of the spectrum, and may in some cases produce a spectral reversal. The bluing effect may be detectable with smaller amounts of weathering than are necessary to detect the longer-wavelength weathering effects.

  9. Space Weathering: An Ultraviolet Indicator

    NASA Technical Reports Server (NTRS)

    Hendrix, A. R.; Vilas, F.

    2003-01-01

    We present evidence suggesting that the spectral slope of airless bodies in the UV-visible wavelength range can be used as an indicator of exposure to space weathering. While space weathering generally produces a reddening of spectra in the visible-NIR spectral regions, it tends to result in a bluing of the UV-visible portion of the spectrum, and may in some cases produce a spectral reversal. The bluing effect may be detectable with smaller amounts of weathering than are necessary to detect the longer-wavelength weathering effects.

  10. Intrinsic Amino Acid Side-Chain Hydrophilicity/Hydrophobicity Coefficients Determined by Reversed-Phase High-Performance Liquid Chromatography of Model Peptides: Comparison with Other Hydrophilicity/Hydrophobicity Scales

    PubMed Central

    Mant, Colin T.; Kovacs, James M.; Kim, Hyun-Min; Pollock, David D.; Hodges, Robert S.

    2009-01-01

    An accurate determination of the intrinsic hydrophilicity/hydrophobicity of amino acid side-chains in peptides and proteins is fundamental in understanding many areas, including protein folding and stability, peptide and protein function, protein-protein interactions and peptide/protein oligomerization, as well as the design of protocols for purification and characterization of peptides and proteins. Our definition of intrinsic hydrophilicity/hydrophobicity of side-chains is the maximum possible hydrophilicity/hydrophobicity of side-chains in the absence of any nearest-neighbor effects and/or any conformational effects of the polypeptide chain that prevent full expression of side-chain hydrophilicity/hydrophobicity. In this review, we have compared an experimentally-derived intrinsic side-chain hydrophilicity/hydrophobicity scale generated from RP-HPLC retention behavior of de novo designed synthetic model peptides at pH 2 and pH 7 with other RP-HPLC-derived scales, as well as scales generated from classic experimental and calculation-based methods of octanol/water partitioning of N?-acetyl-amino-acid amides or free energy of transfer of free amino acids. Generally poor correlation was found with previous RP-HPLC-derived scales, likely due to the random nature of the peptide mixtures in terms of varying peptide size, conformation and frequency of particular amino acids. In addition, generally poor correlation with the classical approaches served to underline the importance of the presence of a polypeptide backbone when generating intrinsic values. We have shown that the intrinsic scale determined here is in full agreement with the structural characteristics of amino acid side-chains. PMID:19795449

  11. Surface-stabilized gold nanocatalysts

    DOEpatents

    Dai, Sheng (Knoxville, TN) [Knoxville, TN; Yan, Wenfu (Oak Ridge, TN) [Oak Ridge, TN

    2009-12-08

    A surface-stabilized gold nanocatalyst includes a solid support having stabilizing surfaces for supporting gold nanoparticles, and a plurality of gold nanoparticles having an average particle size of less than 8 nm disposed on the stabilizing surfaces. The surface-stabilized gold nanocatalyst provides enhanced stability, such as at high temperature under oxygen containing environments. In one embodiment, the solid support is a multi-layer support comprising at least a first layer having a second layer providing the stabilizing surfaces disposed thereon, the first and second layer being chemically distinct.

  12. The AO Ulnar Shortening Osteotomy System Indications and Surgical Technique

    PubMed Central

    Nagy, Ladislav; Jungwirth-Weinberger, Anna; Campbell, Douglas; Pino, Juan González del

    2014-01-01

    Ulnar shortening osteotomy is an established and frequently performed surgical procedure in wrist surgery. The technical aspects of the procedure have continued to develop in recent years, with instruments and implants being developed specifically for this purpose. Ulnar shortening osteotomy is required for different clinical indications and situations. These varying indications demand different amounts of shortening, but all must be precise and accurate. Controversy exists as to how this can best be achieved in terms of the location for osteotomy, the surgical approach and geometry of the osteotomy, as well as which implant to use to provide optimal stability. The goal of all techniques (besides successfully resolving the underlying problem) is to achieve reliable and rapid bone union without compromising early functional rehabilitation and also to avoid hardware complications. The AO Hand Expert Group has developed a specialized instrumentation system with dedicated and specifically designed implants to ensure exact and accurate cutting with precise and rigid stabilization of the ulna. The matched drill guides and double-blade saws allow accurate completion of the planned amount of shortening together with precise coaptation of the osteotomy fragments. The specific ulnar osteotomy LCP (locking compression plate) combines maximum stability with minimum bulk and soft tissue irritation. The features of the implant, its surgical technique, and early results are described. PMID:25077046

  13. The Seabed Stability Zonation in Chinese Offshore

    NASA Astrophysics Data System (ADS)

    Du, J.

    2013-12-01

    There are abundant natural resources and energy in Chinese offshore continental shelf, and which should be the most development potential region now and in the future. But the seabed of Chinese offshore is often under the instable status caused by many factors which deeply affects the safety of marine development. Marine geohazards is an active one among the influence factors. The marine geohazards means the geological factors developed in the seabed surface and the strata below the seabed, such as fault, shallow gas, landslide, coastal erosion, buried river channel, sand wave and sand ridge, easily liquefied sand layer etc., which will cause damage to the human life and property. In this paper, the seabed stability were analyzed and divided it into five grades based on the marine geohazards evaluation result which made by fuzzy mathematic model. Firstly, by collecting the analyzing the marine geohazards which distributed on the seabed or under the seabed, the marine geohazards maps in Chinese offshore were made and the classification system of marine geohazards was established. Then, the evaluation index system of seabed stability was set which included the seismic peak acceleration, geomorphology, direct geohazards and restricted geohazards. And the weighted value of each indicator was calculated by using analytic hierarchy process. And, a group of appropriate number with normal distribution was selected to replace the membership grade function. Based on above, a fuzzy evaluation model for seabed stability is established. Using the maps of marine geohazards, geomorphology maps and seismic peak acceleration maps as data source, using the fuzzy matrix as calculated method, based on the principles of maximum membership grade of fuzzy mathematics, we get the evaluation result of Chinese offshore with 6' by 6' grid unit. The maximum membership grade should be taken as the stability level in each unit. Above all, the seabed stability of Chinese offshore is divided into five grades according to the maximum membership grade. In this paper, we defined 5 classes which respectively were basically stable, relatively stable, medium, relatively unstable and unstable. By using statistical analysis method, a stability zonation map of the Chinese offshore has been drawn based on the evaluation result of each unit. From the stability map, Chinese offshore seabed stability was divided into sixty sub-regions with 5 classes. And the unstable sub-regions were mainly located in the North-East of Liaodong Bay, north of Laizhou Bay, the shoal in north Jiangsu, north Taiwan offshore and around Nan'ao Islands of Guangdong. Most Chinese offshore seabed stability has been in the relatively stable status.

  14. Low latency counter event indication

    DOEpatents

    Gara, Alan G. (Mount Kisco, NY); Salapura, Valentina (Chappaqua, NY)

    2008-09-16

    A hybrid counter array device for counting events with interrupt indication includes a first counter portion comprising N counter devices, each for counting signals representing event occurrences and providing a first count value representing lower order bits. An overflow bit device associated with each respective counter device is additionally set in response to an overflow condition. The hybrid counter array includes a second counter portion comprising a memory array device having N addressable memory locations in correspondence with the N counter devices, each addressable memory location for storing a second count value representing higher order bits. An operatively coupled control device monitors each associated overflow bit device and initiates incrementing a second count value stored at a corresponding memory location in response to a respective overflow bit being set. The incremented second count value is compared to an interrupt threshold value stored in a threshold register, and, when the second counter value is equal to the interrupt threshold value, a corresponding "interrupt arm" bit is set to enable a fast interrupt indication. On a subsequent roll-over of the lower bits of that counter, the interrupt will be fired.

  15. Low latency counter event indication

    DOEpatents

    Gara, Alan G. (Mount Kisco, NY); Salapura, Valentina (Chappaqua, NY)

    2010-08-24

    A hybrid counter array device for counting events with interrupt indication includes a first counter portion comprising N counter devices, each for counting signals representing event occurrences and providing a first count value representing lower order bits. An overflow bit device associated with each respective counter device is additionally set in response to an overflow condition. The hybrid counter array includes a second counter portion comprising a memory array device having N addressable memory locations in correspondence with the N counter devices, each addressable memory location for storing a second count value representing higher order bits. An operatively coupled control device monitors each associated overflow bit device and initiates incrementing a second count value stored at a corresponding memory location in response to a respective overflow bit being set. The incremented second count value is compared to an interrupt threshold value stored in a threshold register, and, when the second counter value is equal to the interrupt threshold value, a corresponding "interrupt arm" bit is set to enable a fast interrupt indication. On a subsequent roll-over of the lower bits of that counter, the interrupt will be fired.

  16. Investigation of physical and chemical stability of ointment with herbals.

    PubMed

    Zdoryk, Oleksandr A; Khokhlova, Kateryna O; Georgiyants, Victoriya A; Vyshnevska, Liliia I

    2014-01-01

    The physical and chemical stability of a stock preparation ointment with active ingredients-herbal tinctures of calendula and arnica-for the treatment of hemorrhoids was studied. Evaluations for physical and chemical stability were performed initially and throughout the storage period. Physical stability of the ointment was assessed by means of visual observation in normal room light. Throughout the study period, the physical appearance of the ointment did not change. The chemical stability of the ointment was evaluated by means of a stability-indicating, thin-layer chromatography analytical technique. The shelf-life was found to be one month at 25 degrees C +/- 2 degrees C/60% RH and two months at 5 degrees C +/- 3 degrees C, when protected from light. PMID:25306773

  17. The ecology of the microbiome: Networks, competition, and stability.

    PubMed

    Coyte, Katharine Z; Schluter, Jonas; Foster, Kevin R

    2015-11-01

    The human gut harbors a large and complex community of beneficial microbes that remain stable over long periods. This stability is considered critical for good health but is poorly understood. Here we develop a body of ecological theory to help us understand microbiome stability. Although cooperating networks of microbes can be efficient, we find that they are often unstable. Counterintuitively, this finding indicates that hosts can benefit from microbial competition when this competition dampens cooperative networks and increases stability. More generally, stability is promoted by limiting positive feedbacks and weakening ecological interactions. We have analyzed host mechanisms for maintaining stability-including immune suppression, spatial structuring, and feeding of community members-and support our key predictions with recent data. PMID:26542567

  18. The superconducting cavity stability ruby maser oscillator

    NASA Technical Reports Server (NTRS)

    Dick, G. J.; Strayer, D. M.

    1985-01-01

    Analysis of an application of the rudy maser to a superconducting Cavity Stabilized oscillator shows many attractive features. These derive from the mechancial stability inherent in an all-cryogenic design and from the properties of the ruby maser itself. A multiple-cavity design has been developed to allow physical separation of the high-Q superconducting cavity and the ruby element with its requried applied magnetic field. Mode selection is accomplished in this design by tuning the ruby by means of the applied field. We conclude that such an oscillator would perform well, even with cavity Q's as low as 10 to the 8th power allowing the use of a superconductor-on-sapphire resonator with its greater rigidity and lower thermal expansion. A first test of the Superconducting Cavity Stabilized Maser Oscillator (SCSMO) confirms the efficacy of the multiple-cavity design and the applicability of the ruby maser. Frequency variation less than 4x10 to the minus 11th power was measured in the stabilized mode and is attributed to the reference oscillator and to instabilities in the pump source. Variation of 10 to the minus 10th power was observed in the low-Q unstabilized mode, again attributable to pump fluctuations. Even so, direct scaling to a Q of 10 the 9th power predicts a stability better than 10 to the minus 15th power. Together with results showing the lowest losses to date in sapphire at microwave frequencies, and preliminary experiments on superconductor-on-sapphire resonators, frequency stability, levels as low as 10 to the minus 17th power are indicated.

  19. Urinary myoglobin quantification by high-performance liquid chromatography: An alternative measurement for exercise-induced muscle damage.

    PubMed

    Lindsay, Angus; Carr, Sam; Draper, Nick; Gieseg, Steven P

    2015-12-15

    This study investigated a means of quantifying urinary myoglobin using a novel reverse-phase high-performance liquid chromatography (RP-HPLC) method that is an alternative measure of exercise-induced muscle damage. It also investigated the effect of storage and alkalization on urinary myoglobin stability issues. An RP-HPLC method was validated by precision and repeatability experiments. Myoglobin stability was determined through spiked urine samples stored at various temperatures over an 8-week period using alkalization and dilution in a pH 7.0 buffer. The method was validated with urine collected from mixed martial arts fighters during a competition and training session. The method produced linearity from 5 to 1000 ?g/ml (R(2) = 0.997), intra- and inter-assay coefficients of variation from 0.32 to 2.94%, and a lower detection limit of 0.2 ?g/ml in the final dilution and 2 ?g/ml in the original urine sample. Recovery ranged from 96.4 to 102.5%, myoglobin remained stable at 4 °C when diluted in a pH 7.0 buffer after 20 h, and a significant increase (P < 0.01) and an identifiable peak were observed following a mixed martial arts contest and training session. Storage length and conditions had significant effects (P < 0.05) on stability. The method's simplicity and noninvasive nature means it can be used as an alternative muscle damage assay following exercise and trauma. PMID:26363103

  20. 'Blueberry' Layers Indicate Watery Origins

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This microscopic image, taken at the outcrop region dubbed 'El Capitan' near the Mars Exploration Rover Opportunity's landing site, reveals millimeter-scale (.04 inch-scale) layers in the lower portion. This same layering is hinted at by the fine notches that run horizontally across the sphere-like grain or 'blueberry' in the center left. The thin layers do not appear to deform around the blueberry, indicating that these geologic features are concretions and not impact spherules or ejected volcanic material called lapilli. Concretions are balls of minerals that form in pre-existing wet sediments. This image was taken by the rover's microscopic imager on the 29th martian day, or sol, of its mission. The observed area is about 3 centimeters (1.2 inches) across.

  1. [Ketamine: psychiatric indications and misuses].

    PubMed

    Delimbeuf, N; Petit, A; Karila, L; Lejoyeux, M

    2014-01-01

    Ketamine or -ketamine hydrochloride- is used as an anesthesic and a painkiller. It may also, in some indications, be prescribed in psychiatry and addictology. A literature review was conducted from 2003 to 2013, in PubMed, Google Scholar, Embase, and Psyclnfo, using the following key words (alone or combined): "ketamine", "abuse", "addiction", "dependence" and "misuse". Various studies have shown the benefit of kétamine in some psychiatric conditions such as major depressive episodes and electroconvulsive therapy. Others have demonstrated beneficial effects in alcohol or opiate abstinence maintenance. Ketamine seems to be a promising molecule in psychiatry and in the treatment of addictions, despite the absence of marketing approval for those specific uses. Being a strong psycho-stimulant, ketamine can be the source of abuse and dependence with somatic, psychiatric and cognitive complications. PMID:25158385

  2. Triboluminescent tamper-indicating device

    DOEpatents

    Johnston, Roger G. (Los Alamos, NM); Garcia, Anthony R. E. (Espanola, NM)

    2002-01-01

    A tamper-indicating device is described. The device has a transparent or translucent cylindrical body that includes triboluminescent material, and an outer opaque layer that prevents ambient light from entering. A chamber in the body holds an undeveloped piece of photographic film bearing an image. The device is assembled from two body members. One of the body members includes a recess for storing film and an optical assembly that can be adjusted to prevent light from passing through the assembly and exposing the film. To use the device with a hasp, the body members are positioned on opposite sides of a hasp, inserted through the hasp, and attached. The optical assembly is then manipulated to allow any light generated from the triboluminescent materials during a tampering activity that damages the device to reach the film and destroy the image on the film.

  3. Multiwavelength star formation indicators: Observations

    E-print Network

    H. R. Schmitt; D. Calzetti; L. Armus; M. Giavalisco; T. M. Heckman; R. C. Kennicutt Jr.; C. Leitherer; G. R. Meurer

    2006-02-03

    We present a compilation of multiwavelength data on different star formation indicators for a sample of nearby star forming galaxies. Here we discuss the observations, reductions and measurements of ultraviolet images obtained with STIS, on board the Hubble Space Telescope, ground-based Halpha, and VLA 8.46 GHz radio images. These observations are complemented with infrared fluxes, as well as large aperture optical radio and ultraviolet data from the literature. This database will be used in a forthcoming paper to compare star formation rates at different wavebands. We also present spectral energy distributions (SEDs) for those galaxies with at least one far-infrared measurements from ISO, longward of 100 um. These SEDs are divided in two groups, those which are dominated by the far-infrared emission, and those where the contribution from the far-infrared and optical emission is comparable. These SEDs are useful tools to study the properties of high redshift galaxies.

  4. Range indices of geomagnetic activity

    USGS Publications Warehouse

    Stuart, W.F.; Green, A.W., Jr.

    1988-01-01

    The simplest index of geomagnetic activity is the range in nT from maximum to minimum value of the field in a given time interval. The hourly range R was recommended by IAGA for use at observatories at latitudes greater than 65??, but was superceded by AE. The most used geomagnetic index K is based on the range of activity in a 3 h interval corrected for the regular daily variation. In order to take advantage of real time data processing, now available at many observatories, it is proposed to introduce a 1 h range index and also a 3 h range index. Both will be computed hourly, i.e. each will have a series of 24 per day, the 3 h values overlapping. The new data will be available as the range (R) of activity in nT and also as a logarithmic index (I) of the range. The exponent relating index to range in nT is based closely on the scale used for computing K values. The new ranges and range indices are available, from June 1987, to users in real time and can be accessed by telephone connection or computer network. Their first year of production is regarded as a trial period during which their value to the scientific and commercial communities will be assessed, together with their potential as indicators of regional and global disturbances' and in which trials will be conducted into ways of eliminating excessive bias at quiet times due to the rate of change of the daily variation field. ?? 1988.

  5. Dynamically stabilized magnetic skyrmions

    NASA Astrophysics Data System (ADS)

    Zhou, Y.; Iacocca, E.; Awad, A. A.; Dumas, R. K.; Zhang, F. C.; Braun, H. B.; Åkerman, J.

    2015-09-01

    Magnetic skyrmions are topologically non-trivial spin textures that manifest themselves as quasiparticles in ferromagnetic thin films or noncentrosymmetric bulk materials. So far attention has focused on skyrmions stabilized either by the Dzyaloshinskii-Moriya interaction (DMI) or by dipolar interaction, where in the latter case the excitations are known as bubble skyrmions. Here we demonstrate the existence of a dynamically stabilized skyrmion, which exists even when dipolar interactions and DMI are absent. We establish how such dynamic skyrmions can be nucleated, sustained and manipulated in an effectively lossless medium under a nanocontact. As quasiparticles, they can be transported between two nanocontacts in a nanowire, even in complete absence of DMI. Conversely, in the presence of DMI, we observe that the dynamical skyrmion experiences strong breathing. All of this points towards a wide range of skyrmion manipulation, which can be studied in a much wider class of materials than considered so far.

  6. Dynamically stabilized magnetic skyrmions

    PubMed Central

    Zhou, Y.; Iacocca, E.; Awad, A. A.; Dumas, R. K.; Zhang, F. C.; Braun, H. B.; Åkerman, J.

    2015-01-01

    Magnetic skyrmions are topologically non-trivial spin textures that manifest themselves as quasiparticles in ferromagnetic thin films or noncentrosymmetric bulk materials. So far attention has focused on skyrmions stabilized either by the Dzyaloshinskii–Moriya interaction (DMI) or by dipolar interaction, where in the latter case the excitations are known as bubble skyrmions. Here we demonstrate the existence of a dynamically stabilized skyrmion, which exists even when dipolar interactions and DMI are absent. We establish how such dynamic skyrmions can be nucleated, sustained and manipulated in an effectively lossless medium under a nanocontact. As quasiparticles, they can be transported between two nanocontacts in a nanowire, even in complete absence of DMI. Conversely, in the presence of DMI, we observe that the dynamical skyrmion experiences strong breathing. All of this points towards a wide range of skyrmion manipulation, which can be studied in a much wider class of materials than considered so far. PMID:26351104

  7. Dynamically stabilized magnetic skyrmions.

    PubMed

    Zhou, Y; Iacocca, E; Awad, A A; Dumas, R K; Zhang, F C; Braun, H B; Åkerman, J

    2015-01-01

    Magnetic skyrmions are topologically non-trivial spin textures that manifest themselves as quasiparticles in ferromagnetic thin films or noncentrosymmetric bulk materials. So far attention has focused on skyrmions stabilized either by the Dzyaloshinskii-Moriya interaction (DMI) or by dipolar interaction, where in the latter case the excitations are known as bubble skyrmions. Here we demonstrate the existence of a dynamically stabilized skyrmion, which exists even when dipolar interactions and DMI are absent. We establish how such dynamic skyrmions can be nucleated, sustained and manipulated in an effectively lossless medium under a nanocontact. As quasiparticles, they can be transported between two nanocontacts in a nanowire, even in complete absence of DMI. Conversely, in the presence of DMI, we observe that the dynamical skyrmion experiences strong breathing. All of this points towards a wide range of skyrmion manipulation, which can be studied in a much wider class of materials than considered so far. PMID:26351104

  8. Morphological Stability of Faceted Interfaces

    NASA Technical Reports Server (NTRS)

    Abbaschian, Reza; Golyshev, V. D.; Gonik, M.; Tsvetivsky, V.; deVahlDavis, G.; Leonardi, E.

    2001-01-01

    The major focus of this investigation is to study the fundamentals of layer spreading mechanisms during growth of doped Ge (a facet forming material), and to determine the conditions for morphological instability of vicinal solid-liquid interfaces. The investigation will also lead to the determination of the effect of dopants on the layer growth kinetics, step free energy, and dopant capture by the advancing ledges. The theoretical treatment of growth of faceted interfaces indicates that the kinetics of a step on a growing vicinal interface considerably depends on its angle of inclination, the melt concentration, and characteristics of flow currents in the melt. The morphological stability of the interface also depends on these parameters, as well as on the density and spreading velocity of the steps. However, the treatment of the instability of the interface by the layer growth mechanism is rather difficult because it requires exact knowledge of the thermal and solutal fields, hydrodynamics of the melt, and supercooling at the interface. The results of recent space experiments of the principal investigator involving directional solidification of faceted Bi-Sn alloys have shown that the morphological stability of various crystallographic orientations is significantly affected by the anistropy in interfacial properties of the faceted alloy in general, and the interface kinetics in particular. These findings have also raised many important and fundamental questions, particularly with respect to the behavior of interfacial steps, which need to be addressed via additional groundbased and microgravity experiments. For the present investigation we will use a novel crystal growth technique which provides axial heat flux close to the solid-liquid boundary. The Axial Heat Processing (AHP) technique allows for precise control and determination of the heat and mass transfer close to the crystallization front, and the establishment of a planar interface over the entire cross-section of the growing crystal.

  9. Feasibility study of inlet shock stability system of YF-12

    NASA Technical Reports Server (NTRS)

    Blausey, G. C.; Coleman, D. M.; Harp, D. S.

    1972-01-01

    The feasibility of self actuating bleed valves as a shock stabilization system in the inlet of the YF-12 is considered for vortex valves, slide valves, and poppet valves. Analytical estimation of valve performance indicates that only the slide and poppet valves located in the inlet cowl can meet the desired steady state stabilizing flows, and of the two the poppet valve is substantially faster in response to dynamic disturbances. The poppet valve is, therefore, selected as the best shock stability system for the YF-12 inlet.

  10. Solar absorber material stability under high solar flux

    NASA Astrophysics Data System (ADS)

    Ignatiev, A.; Zajac, G.; Smith, G. B.

    1982-04-01

    Solar absorbing Black Chrome coatings have been exposed to high temperatures (350-400 C) under high solar fluxes (0.4 to 2.0 MW/sq m) to test for their stability under actual operating conditions. Field tests at the White Sands Solar Furnace have shown higher stability than expected from oven tested samples. Laboratory studies utilizing spectrally selective concentrated solar simulated radiation have indicated that the cause of the higher stability under solar irradiation is photo-stimulated desorption of oxygen bearing species at the absorber surface and resultant reduced oxidation of the absorber.

  11. Stability determination of crude oil emulsions by electrorheological measurement

    NASA Astrophysics Data System (ADS)

    Alvarado, Vladimir; Wang, Xiuyu; Plancher, Henry

    2008-11-01

    Emulsion stability is paramount to the success of many industrial applications and the remediation of naturally undesirable occurring fluid-fluid dispersions. Bottle tests and critical electric field (Ec) measurements are two commonly used techniques to interpret emulsion stability. In the former, the amount of water resolved after gravitational settling test or centrifugation as a function of time is used as an indicator of stability. Generally, the lower the total water fraction resolved, the higher the emulsion stability. In the second method, the value of Ec leading to drop coalescence is used as an indicator of stability. A larger value of Ec is a reflection of a more stable dispersion. The value of Ec is usually determined by measuring a sudden increase in electrical conductivity in water-crude oil emulsions as the field value is increased. In this work, an electrorheological test is used to establish the value of Ec and hence the stability criterion. Results of electrorheological measurements are compared to results of bottle tests for water-crude oil emulsions with or without stabilizing solid micro-particles. Results will show the consistency among the different measuring techniques, for a wide range of ionic strength and composition of the water phase and two crude oils.

  12. Stabilization of polyaniline solutions

    SciTech Connect

    Wrobleski, D.A.; Benicewicz, B.C.

    1993-12-01

    Adding hindered amine light stabilizers (HALS) to N-methyl- pyrrolidinone (NMP) solutions of polyaniline delays gelation. It is hypothesized that HALS act in some manner other than as traditional antioxidants in preventing gelation; the secondary amine functional group appears to play a critical role, perhaps by disrupting the physical crystallization network that may contribute to gelation. Pyrrolidine, a secondary amine, or ammonia is an effective cosolvent with NMP in dissolving PAn-EB (emeraldine base). 6 refs, 4 figs.

  13. Rock slope stability

    SciTech Connect

    Kliche, C.A.

    1999-07-01

    Whether you're involved in surface mine design, surface mine production, construction, education, or regulation, this is an important new book for your library. It describes the basic rock slope failure modes and methods of analysis--both kinematic and kinetic techniques. Chapters include geotechnical and geomechanical analysis techniques, hydrology, rock slope stabilization techniques, and geotechnical instrumentation and monitoring. Numerous examples, drawings and photos enhance the text.

  14. Diffusion Flame Stabilization

    NASA Technical Reports Server (NTRS)

    Takahashi, Fumiaki; Katta, Viswanath R.

    2007-01-01

    Diffusion flames are commonly used for industrial burners in furnaces and flares. Oxygen/fuel burners are usually diffusion burners, primarily for safety reasons, to prevent flashback and explosion in a potentially dangerous system. Furthermore, in most fires, condensed materials pyrolyze, vaporize, and burn in air as diffusion flames. As a result of the interaction of a diffusion flame with burner or condensed-fuel surfaces, a quenched space is formed, thus leaving a diffusion flame edge, which plays an important role in flame holding in combustion systems and fire spread through condensed fuels. Despite a long history of jet diffusion flame studies, lifting/blowoff mechanisms have not yet been fully understood, compared to those of premixed flames. In this study, the structure and stability of diffusion flames of gaseous hydrocarbon fuels in coflowing air at normal earth gravity have been investigated experimentally and computationally. Measurements of the critical mean jet velocity (U(sub jc)) of methane, ethane, or propane at lifting or blowoff were made as a function of the coflowing air velocity (U(sub a)) using a tube burner (i.d.: 2.87 mm) (Fig. 1, left). By using a computational fluid dynamics code with 33 species and 112 elementary reaction steps, the internal chemical-kinetic structures of the stabilizing region of methane and propane flames were investigated (Fig. 1, right). A peak reactivity spot, i.e., reaction kernel, is formed in the flame stabilizing region due to back-diffusion of heat and radical species against an oxygen-rich incoming flow, thus holding the trailing diffusion flame. The simulated flame base moved downstream under flow conditions close to the measured stability limit.

  15. Diffusion Flame Stabilization

    NASA Technical Reports Server (NTRS)

    Takahashi, Fumiaki; Katta, V. R.

    2006-01-01

    Diffusion flames are commonly used for industrial burners in furnaces and flares. Oxygen/fuel burners are usually diffusion burners, primarily for safety reasons, to prevent flashback and explosion in a potentially dangerous system. Furthermore, in most fires, condensed materials pyrolyze, vaporize, and burn in air as diffusion flames. As a result of the interaction of a diffusion flame with burner or condensed-fuel surfaces, a quenched space is formed, thus leaving a diffusion flame edge, which plays an important role in flame holding in combustion systems and fire spread through condensed fuels. Despite a long history of jet diffusion flame studies, lifting/blowoff mechanisms have not yet been fully understood, compared to those of premixed flames. In this study, the structure and stability of diffusion flames of gaseous hydrocarbon fuels in coflowing air at normal earth gravity have been investigated experimentally and computationally. Measurements of the critical mean jet velocity (U(sub jc)) of methane, ethane, or propane at lifting or blowoff were made as a function of the coflowing air velocity (U(sub a)) using a tube burner (i.d.: 2.87 mm). By using a computational fluid dynamics code with 33 species and 112 elementary reaction steps, the internal chemical-kinetic structures of the stabilizing region of methane and propane flames were investigated. A peak reactivity spot, i.e., reaction kernel, is formed in the flame stabilizing region due to back-diffusion of heat and radical species against an oxygen-rich incoming flow, thus holding the trailing diffusion flame. The simulated flame base moved downstream under flow conditions close to the measured stability limit.

  16. Quantum convolutional stabilizer codes 

    E-print Network

    Chinthamani, Neelima

    2004-09-30

    QUANTUM CONVOLUTIONAL STABILIZER CODES A Thesis by NEELIMA CHINTHAMANI Submitted to Texas A&M University in partial ful¯llment of the requirements for the degree of MASTER OF SCIENCE Approved as to style and content by: Andreas Klappenecker (Chair... Technological University, India Chair of Advisory Committee: Dr. Andreas Klappenecker Quantum error correction codes were introduced as a means to protect quantum informa- tion from decoherance and operational errors. Based on their approach to error control...

  17. Determining postural stability

    NASA Technical Reports Server (NTRS)

    Lieberman, Erez (Inventor); Forth, Katharine E. (Inventor); Paloski, William H. (Inventor)

    2011-01-01

    A method for determining postural stability of a person can include acquiring a plurality of pressure data points over a period of time from at least one pressure sensor. The method can also include the step of identifying a postural state for each pressure data point to generate a plurality of postural states. The method can include the step of determining a postural state of the person at a point in time based on at least the plurality of postural states.

  18. Stability, transition and turbulence

    NASA Technical Reports Server (NTRS)

    Hussaini, M. Y.

    1987-01-01

    A glimpse is provided of the research program in stability, transition, and turbulence based on numerical simulations. This program includes both the so-called abrupt and the restrained transition processes. Attention is confined to the prototype problems of channel flow and the parallel boundary layer in the former category and the Taylor-Couette flow in the latter category. It covers both incompressible flows and supersonic flows. Some representative results are presented.

  19. Stabilized Lasers and Precision Measurements.

    ERIC Educational Resources Information Center

    Hall, J. L.

    1978-01-01

    Traces the development of stabilized lasers from the Massachusetts Institute of Technology passive-stabilization experiments of the early 1960s up through the current epoch of highly stabilized helium-neon and carbon dioxide and continuous wave dye lasers. (Author/HM)

  20. ITER global stability limits

    SciTech Connect

    Hogan, J.T.; Uckan, N.A.

    1990-01-01

    The MHD stability limits to the ITER operational space have been examined with the PEST ideal stability code. Constraints on ITER operation have been examined for the nominal operational scenarios and for possible design variants. Rather than rely on evaluation of a relatively small number of sample cases, the approach has been to construct an approximation to the overall operational space, and to compare this with the observed limits in high-{beta} tokamaks. An extensive database with {approximately}20,000 stability results has been compiled for use by the ITER design team. Results from these studies show that the design values of the Troyon factor (g {approximately} 2.5 for ignition studies, and g {approximately} 3 for the technology phase) which are based on present experiments, are also expected to be attainable for ITER conditions, for which the configuration and wall-stabilisation environment differ from those in present experiments. Strongly peaked pressure profiles lead to degraded high-{beta} performance. Values of g {approximately} 4 are found for higher safety factor (q {sub {Psi}} {le} 4) than that of the present design (q{sub {Psi}} {approximately} 3). Profiles with q(0) < 1 are shown to give g {approximately} 2.5, if the current density profile provides optimum shear. The overall operational spaces are presented for g-q{sub {Psi}}, q{sub {Psi}}-1{sub i}, q-{alpha}{sub p} and l{sub i}-q{sub {psi}}.

  1. MULTIPLE OSCILLATION STABILIZING CONTROL.

    SciTech Connect

    YUE,M.; SCHLUETER,R.; AZARM,M.; BARI,R.

    2004-07-23

    This paper presents a strategy that may be used to guide stabilizing control design for multiple oscillations, which are difficult to control using conventional control design procedures. A multiple oscillation phenomena is observed in an example power system. A local bifurcation and an interarea bifurcation develop in an example power system due to multiple bifurcation parameter variations. The dynamic behaviors of the bifurcating system are complex due to the overlapping of the two different bifurcation subsystems and are shown to be difficult to control. The double bifurcations are studied in this paper and in order to stabilize them, three kind of {mu}-synthesis robust controls are designed, (a) {mu}-synthesis power system stabilizer (MPSS); (b) {mu}-synthesis SVC control (MSVC); and (c) a mixed MPSS/MSVC control. Based on the bifurcation subsystem analysis, the measurement signals and locations of the controls are selected. The control performances of three kind of controls are evaluated and compared. The conclusions are given according to the analysis and time simulation results.

  2. Space Elevator: Stability

    NASA Astrophysics Data System (ADS)

    Perek, Lubos

    2008-04-01

    Many papers have been published on engineering and economic aspects of the Space Elevator. The Elevator, however, is a very special and unusual astronomical body. Its behavior in space is affected not only by the attraction of the Earth and by the "centrifugal force" but also by the attraction of the Sun and the Moon, by the detailed shape of the Earth, by the presence of space debris, etc. Not all of the minor effects have been adequately studied. The size of the Space Elevator and its lack of resistance against buckling or bending require a detailed study of its stability, both in its initial phase as a geostationary (GEO) satellite as well as in its operational phase as a "sling". Lunisolar perturbations and other minor forces may affect the stability in the initial phase and will cause oscillations in the operational phase. Station-keeping thrusters will have to be mounted at selected points along the cable in order to maintain stability. In addition, the thrusters will perform local maneuvers for avoiding collisions with passing space debris. The control system of thrusters has to be adaptive, reacting fast to actual situation and rectifying the attitude of the Elevator whenever necessary. A further advantage of the thrusters is a possibility to locate the Elevator at any longitude, possibly looking for a region with minimum traffic at GEO distance. Extensive numerical simulations will have to be performed in order to determine elements of the thrusters and their control system.

  3. Tamper-indicating quantum optical seals

    SciTech Connect

    Humble, Travis S; Williams, Brian P

    2015-01-01

    Confidence in the means for identifying when tampering occurs is critical for containment and surveillance technologies. Fiber-optic seals have proven especially useful for actively surveying large areas or inventories due to the extended transmission range and flexible layout of fiber. However, it is reasonable to suspect that an intruder could tamper with a fiber-optic sensor by accurately replicating the light transmitted through the fiber. In this contribution, we demonstrate a novel approach to using fiber-optic seals for safeguarding large-scale inventories with increased confidence in the state of the seal. Our approach is based on the use of quantum mechanical phenomena to offer unprecedented surety in the authentication of the seal state. In particular, we show how quantum entangled photons can be used to monitor the integrity of a fiber-optic cable - the entangled photons serve as active sensing elements whose non-local correlations indicate normal seal operation. Moreover, we prove using the quantum no-cloning theorem that attacks against the quantum seal necessarily disturb its state and that these disturbances are immediately detected. Our quantum approach to seal authentication is based on physical principles alone and does not require the use of secret or proprietary information to ensure proper operation. We demonstrate an implementation of the quantum seal using a pair of entangled photons and we summarize our experimental results including the probability of detecting intrusions and the overall stability of the system design. We conclude by discussing the use of both free-space and fiber-based quantum seals for surveying large areas and inventories.

  4. Ecological stability in response to warming

    NASA Astrophysics Data System (ADS)

    Fussmann, Katarina E.; Schwarzmüller, Florian; Brose, Ulrich; Jousset, Alexandre; Rall, Björn C.

    2014-03-01

    That species’ biological rates including metabolism, growth and feeding scale with temperature is well established from warming experiments. The interactive influence of these changes on population dynamics, however, remains uncertain. As a result, uncertainty about ecological stability in response under warming remains correspondingly high. In previous studies, severe consumer extinction waves in warmed microcosms were explained in terms of warming-induced destabilization of population oscillations. Here, we show that warming stabilizes predator-prey dynamics at the risk of predator extinction. Our results are based on meta-analyses of a global database of temperature effects on metabolic and feeding rates and maximum population size that includes species of different phylogenetic groups and ecosystem types. To unravel population-level consequences we parameterized a bioenergetic predator-prey model and simulated warming effects within ecological, non-evolutionary timescales. In contrast to previous studies, we find that warming stabilized population oscillations up to a threshold temperature, which is true for most of the possible parameter combinations. Beyond the threshold level, warming caused predator extinction due to starvation. Predictions were tested in a microbial predator-prey system. Together, our results indicate a major change in how we expect climate change to alter natural ecosystems: warming should increase population stability while undermining species diversity.

  5. Stability analysis of White Oak Dam

    SciTech Connect

    1995-04-11

    White Oak Dam is located in the White Oak Creek watershed which provides the primary surface drainage for Oak Ridge National Laboratory. A stability analysis was made on the dam by Syed Ahmed in January 1994 which included an evaluation of the liquefaction potential of the embankment and foundation. This report evaluates the stability of the dam and includes comments on the report prepared by Ahmed. Slope stability analyses were performed on the dam and included cases for sudden drawdown, steady seepage, partial pool and earthquake. Results of the stability analyses indicate that the dam is stable and failure of the structure would not occur for the cases considered. The report prepared by Ahmed leads to the same conclusions as stated above. Review of the report finds that it is complete, well documented and conservative in its selection of soil parameters. The evaluation of the liquefaction potential is also complete and this report is in agreement with the findings that the dam and foundation are not susceptible to liquefaction.

  6. Stability of Sulforaphane for Topical Formulation

    PubMed Central

    Franklin, Stephen J.; Dickinson, Sally E.; Karlage, Kelly L.; Bowden, G Tim.; Myrdal, Paul B.

    2013-01-01

    Sulforaphane (SFN) is a natural compound that has been investigated as a chemopreventive agent. SFN has been shown to inhibit the activator-protein-1 (AP-1) transcription factor and may be effective for inhibition of ultraviolet (UV) induced skin carcinogenesis. This study was designed to investigate the stability of SFN as a function of pH, temperature and in various solvents and formulations. SFN was determined to undergo apparent first order degradation kinetics for the conditions explored. It was observed that SFN undergoes base catalyzed degradation. Buffer species and solvent type impacts stability as well. SFN was found to be very sensitive to temperature with degradation rate changing by a factor of nearly 3.1 for every 10°C change in temperature (at pH 4.0). SFN completely degraded after 30 days in a conventional pharmaceutical cream formulation. Improved stability was observed in organic formulation components. Stability studies were conducted on two non-aqueous topical formulations, a polyethylene glycol (PEG) ointment base and an organic oleaginous base. Topically applied SFN in the PEG base formulation significantly reduced AP-1 activation after UV stimulation in the skin of a transgenic mouse model, indicating that SFN in this formulation retains efficacy in vivo. PMID:23611476

  7. Thiol-Disulfide Exchange in Peptides Derived from Human Growth Hormone during Lyophilization and Storage in the Solid State

    PubMed Central

    Chandrasekhar, Saradha; Topp, Elizabeth M.

    2015-01-01

    Lyophilization (freeze-drying) is frequently used to stabilize protein therapeutics. However, covalent modifications such as thiol-disulfide exchange and disulfide scrambling can occur even in the solid state. The effects of lyophilization and storage of lyophilized powders on the mechanism and kinetics of thioldisulfide exchange have not been elucidated and are explored here. Reaction kinetics were monitored in peptides corresponding to tryptic fragments of human growth hormone (T20 + T20-T21 or T20 + cT20-T21) during different stages of lyophilization and during storage of the lyophilized powders at 22 °C and ambient RH. The concentrations of reactants and products were determined using RP-HPLC and product identity confirmed using LC-MS. Loss of native disulfide was observed for the reaction of T20 with both linear (T20-T21) and cyclic (cT20-T21) peptides during the primary drying step, however, the native disulfides were regenerated during secondary drying with no further change till the end of lyophilization. Deviations from Arrhenius parameters predicted from solution studies and the absence of buffer effects during lyophilization suggest that factors such as temperature, initial peptide concentration, buffer type and concentration do not influence thiol-disulfide exchange during lyophilization. Results from a ‘cold finger’ method used to study peptide adsorption to ice indicate that there is no preferential adsorption to the ice surface and that its presence may not influence disulfide reactivity during primary drying. Overall, reaction rates and product distribution differ for the reaction of T20 with T20-T21 or cT20-T21 in the solid state and aqueous solution, while the mechanism of thiol-disulfide remains unchanged. Increased reactivity of the cyclic peptide in the solid state suggests that peptide cyclization does not offer protection against lyophilization and that damage induced by a process stress further affects storage stability at 22 °C and ambient RH. PMID:25631887

  8. Thiol-disulfide exchange in peptides derived from human growth hormone during lyophilization and storage in the solid state.

    PubMed

    Chandrasekhar, Saradha; Topp, Elizabeth M

    2015-04-01

    Lyophilization (freeze-drying) is frequently used to stabilize protein therapeutics. However, covalent modifications such as thiol-disulfide exchange and disulfide scrambling can occur even in the solid state. The effects of lyophilization and storage of lyophilized powders on the mechanism and kinetics of thiol-disulfide exchange have not been elucidated and are explored here. Reaction kinetics was monitored in peptides corresponding to tryptic fragments of human growth hormone (T20 + T20-T21 or T20 + cT20-T21) during different stages of lyophilization and during storage of the lyophilized powders at 22°C and ambient RH. The concentrations of reactants and products were determined using RP-HPLC and product identity confirmed using liquid chromatography-mass spectrometry. Loss of native disulfide was observed for the reaction of T20 with both linear (T20-T21) and cyclic (cT20-T21) peptides during the primary drying step; however, the native disulfides were regenerated during secondary drying with no further change till the end of lyophilization. Deviations from Arrhenius parameters predicted from solution studies and the absence of buffer effects during lyophilization suggest that factors such as temperature, initial peptide concentration, buffer type, and concentration do not influence thiol-disulfide exchange during lyophilization. Results from a "cold finger" method used to study peptide adsorption to ice indicate that there is no preferential adsorption to the ice surface and that its presence may not influence disulfide reactivity during primary drying. Overall, reaction rates and product distribution differ for the reaction of T20 with T20-T21 or cT20-T21 in the solid state and aqueous solution, whereas the mechanism of thiol-disulfide remains unchanged. Increased reactivity of the cyclic peptide in the solid state suggests that peptide cyclization does not offer protection against lyophilization and that damage induced by a process stress further affects storage stability at 22°C and ambient RH. PMID:25631887

  9. Indicating anthropogenic effectson urban water system - indicators and extension

    NASA Astrophysics Data System (ADS)

    Strauch, G.; Ufz-Team

    2003-04-01

    Urban water systems are polluted by diffusive and direct contribution of anthropogenic activities. Besides industrial contaminants like aromatic and chlorinated HC and other persistent organic compounds, the urban aquatic environment is increasingly polluted by low concentrated but high eco-toxic compounds as pharmaceuticals, fragrances, plasticizers which most have disrupt endocrine functions, and trace elements carried in by surface and sub-surface waste water and seeping processes. This contamination could have a longtime impact on the urban ecosystem and on the human health. The interdisciplinary project on risk assessment of water pollution was initiated to explore new methodologies for assessing human activities on the urban water system and processes among urban watersheds. In a first assumption we used a flow model concept with in- and output and surface water transport represented by the city of Halle, Germany, and the river Saale. The river Saale acts as surface water system collecting waste water inputs along the city traverse. We investigated the anthropogenic effect on the urban water system using the indicators hydrological parameters, compound specific pattern of complex organic substances and trace elements, isotopic signatures of water (H, O) and dissolved substances (sulfate, DIC, nitrate), pathogens, and microbiota. A first balance modeling showed that main ions are not very sensitive concerning the direct urban input into the river. Depending on the discharge of the river in high and low flood stages the load of dissolved matter has no specific urban effect. However, the concentration pattern of fragrances (tonalid, galaxolid) and endocrine disrupters (t-nonylphenol) point to a different pollution along the city traverse: downstream of the sewage plant a higher load was observed in comparison to the upstream passage. Furthermore, a degradation ability of fungi and bacteria occurred in the bank sediments could be detected in lab experiments concerning the fragrances, and endocrine disrupters (t-nonylphenol, phthalate). The Saale water samples contain components able to eco-toxic and immunomodulated effects as measured on the vitality and cytokine-secretion profile of human peripheral blood mononuclear cells (PBMC). Even fragrances caused such effects which are unknown so far. The study of assessing urban effects onto the water system is still under investigation.

  10. Optically broadcasting wind direction indicator

    NASA Technical Reports Server (NTRS)

    Zysko, Jan A. (inventor)

    1994-01-01

    An optically broadcasting wind direction indicator generates flashes of light which are separated by a time interval that is directly proportional to the angle of the wind direction relative to a fixed direction, such as north. An angle/voltage transducer generates a voltage that is proportional to the wind direction relative to the fixed direction, and this voltage is employed by timing circuitry or a microprocessor that generates pulses for actuating a light source trigger circuit first at the start of the time interval, and then at the end of the time interval. To aid an observer in distinguishing between the beginning and end of the interval, two stop flashes can be provided in quick succession. The time scale is preferably chosen so that each second of the time interval corresponds to 30 deg of direction relative to north. In this manner, an observer can easily correlate the measured time interval to the wind direction by visualizing the numbers on a conventional clock face, each of which correspond to one second of time and 30 deg of angle.

  11. Criteria to indicate testosterone administration.

    PubMed Central

    Kicman, A T; Brooks, R V; Collyer, S C; Cowan, D A; Nanjee, M N; Southan, G J; Wheeler, M J

    1990-01-01

    A detection method for testosterone administration was developed using radioimmunoassay to measure the urinary ratios of testosterone (T) to epitestosterone (E) and to luteinizing hormone (LH). A comparative study of the effect on these ratios of a single intramuscular injection of testosterone heptanoate followed by stimulation with human chorionic gonadotrophin (HCG) in three normal men was undertaken. To allow immediate investigation, a commercially supplied epitestosterone antiserum was used. This study showed that both T/E and T/LH ratios could be used to detect testosterone administration, the latter also being an indicator of HCG use due to cross-reactivity with the LH antiserum. Subsequently, an epitestosterone antiserum of superior specificity was raised and used in a study to demonstrate the insignificant effect of exercise on these ratios. Finally, an intramuscular injection of a combined preparation of testosterone/epitestosterone heptanoates resulted in raised ratios of T/LH but not of T/E. This demonstrated the importance of the T/LH ratio in circumstances where the T/E ratio can be easily circumvented. PMID:2097025

  12. Integrated Initiating Event Performance Indicators

    SciTech Connect

    S. A. Eide; Dale M. Rasmuson; Corwin L. Atwood

    2005-09-01

    The U.S. Nuclear Regulatory Commission Industry Trends Program (ITP) collects and analyses industry-wide data, assesses the safety significance of results, and communicates results to Congress and other stakeholders. This paper outlines potential enhancements in the ITP to comprehensively cover the Initiating Events Cornerstone of Safety. Future work will address other cornerstones of safety. The proposed Tier 1 activity involves collecting data on ten categories of risk-significant initiating events, trending the results, and comparing early performance with prediction limits (allowable numbers of events, above which NRC action may occur). Tier 1 results would be used to monitor industry performance at the level of individual categories of initiating events. The proposed Tier 2 activity involves integrating the information for individual categories of initiating events into a single risk-based indicator, termed the Baseline Risk Index for Initiating Events or BRIIE. The BRIIE would be evaluated yearly and compared against a threshold. BRIIE results would be reported to Congress on a yearly basis.

  13. Butterflied bivalves as paleoenvironmental indicators

    SciTech Connect

    Allmon, R.A.

    1985-01-01

    Fossil bivalves are seldom preserved in a flat-open, yet still articulated position, or butterflied. A study of butterflied bivalves in the Delphi Station of the Hamilton Fm. suggests that this preservation mode is limited to one or possibly two sedimentary environments: deltaic and fluvial. Three parameters control the mode of preservation of fossil bivalves: 1) rate of sedimentation, 2) depth of bioturbation, and 3) time of ligament failure. Using these three parameters a model for the occurrence of butterflied bivalves can be constructed: bioturbation depth divided by sedimentation rate gives the disturbance time (DST), during which shells on one bedding plane would be subject to reworking. This can be seen as a time window into which ligament failure times - or disarticulation time (DAT) - can be fitted. If DATindicators of conditions prevailing in environments of deposition.

  14. MASCOT - MATLAB Stability and Control Toolbox

    NASA Technical Reports Server (NTRS)

    Kenny, Sean; Crespo, Luis

    2011-01-01

    MASCOT software was created to provide the conceptual aircraft designer accurate predictions of air vehicle stability and control characteristics. The code takes as input mass property data in the form of an inertia tensor, aerodynamic loading data, and propulsion (i.e. thrust) loading data. Using fundamental non-linear equations of motion, MASCOT then calculates vehicle trim and static stability data for any desired flight condition. Common predefined flight conditions are included. The predefined flight conditions include six horizontal and six landing rotation conditions with varying options for engine out, crosswind and sideslip, plus three takeoff rotation conditions. Results are displayed through a unique graphical interface developed to provide stability and control information to the conceptual design engineers using a qualitative scale indicating whether the vehicle has acceptable, marginal, or unacceptable static stability characteristics. This software allows the user to prescribe the vehicle s CG location, mass, and inertia tensor so that any loading configuration between empty weight and maximum take-off weight can be analyzed. The required geometric and aerodynamic data as well as mass and inertia properties may be entered directly, passed through data files, or come from external programs such as Vehicle Sketch Pad (VSP). The current version of MASCOT has been tested with VSP used to compute the required data, which is then passed directly into the program. In VSP, the vehicle geometry is created and manipulated. The aerodynamic coefficients, stability and control derivatives, are calculated using VorLax, which is now available directly within VSP. MASCOT has been written exclusively using the technical computing language MATLAB . This innovation is able to bridge the gap between low-fidelity conceptual design and higher-fidelity stability and control analysis. This new tool enables the conceptual design engineer to include detailed static stability and trim constraints in the conceptual design loop. The unique graphical interface developed for this tool presents the stability data in a format that is understandable by the conceptual designer, yet also provides the detailed quantitative results if desired.

  15. Evaluation of the thermal stability of Gardasil.

    PubMed

    Shank-Retzlaff, Mary L; Zhao, Qinjian; Anderson, Carrie; Hamm, Melissa; High, Katrina; Nguyen, Mai; Wang, Feng; Wang, Ning; Wang, Bei; Wang, Yang; Washabaugh, Michael; Sitrin, Robert; Shi, Li

    2006-01-01

    The thermostability of GARDASIL (Merck & Co., Inc, Whitehouse Station, NJ, USA), a developmental vaccine against human papillomavirus (HPV), was evaluated using an enzyme immunoassay, referred to as the in vitro relative potency (IVRP) assay and differential scanning calorimetry (DSC). Gardasil samples were stored at temperatures ranging from 4 to 42 degrees C and tested for IVRP at various time points. Extrapolation of the IVRP results indicates GARDASIL is extremely stable. The half-life of the vaccine is estimated to be 130 months or longer at temperatures up to 25 degrees C. At 37 degrees C, the half-life is predicted to be 18 months and at 42 degrees C, the half-life is predicted to be approximately three months. Differential scanning calorimetry (DSC) analysis was used to evaluate the process of protein denaturation during a rapid temperature increase (as opposed to long-term storage at a specific temperature). Differences were seen among the DSC profiles of the four HPV types tested. This indicates that small differences in the amino acid structure can have a significant effect on the intermolecular contacts that stabilize the L1 proteins and the VLP assembly. For the Gardasil samples evaluated here, DSC results demonstrated the relative overall structural stability of the VLPs, but were not predictive of the excellent long-term stability observed with the IVRP assay. PMID:17012891

  16. Tamper-indicating barcode and method

    SciTech Connect

    Cummings, Eric B.; Even, Jr., William R.; Simmons, Blake A.; Dentinger, Paul Michael

    2005-03-22

    A novel tamper-indicating barcode methodology is disclosed that allows for detection of alteration to the barcode. The tamper-indicating methodology makes use of a tamper-indicating means that may be comprised of a particulate indicator, an optical indicator, a deformable substrate, and/or may be an integrated aspect of the barcode itself. This tamper-indicating information provides greater security for the contents of containers sealed with the tamper-indicating barcodes.

  17. Validated stability-indicating spectrofluorimetric methods for the determination of ebastine in pharmaceutical preparations

    PubMed Central

    2011-01-01

    Two sensitive, selective, economic, and validated spectrofluorimetric methods were developed for the determination of ebastine (EBS) in pharmaceutical preparations depending on reaction with its tertiary amino group. Method I involves condensation of the drug with mixed anhydrides (citric and acetic anhydrides) producing a product with intense fluorescence, which was measured at 496 nm after excitation at 388 nm. Method (IIA) describes quantitative fluorescence quenching of eosin upon addition of the studied drug where the decrease in the fluorescence intensity was directly proportional to the concentration of ebastine; the fluorescence quenching was measured at 553 nm after excitation at 457 nm. This method was extended to (Method IIB) to apply first and second derivative synchronous spectrofluorimetric method (FDSFS & SDSFS) for the simultaneous analysis of EBS in presence of its alkaline, acidic, and UV degradation products. The proposed methods were successfully applied for the determination of the studied compound in its dosage forms. The results obtained were in good agreement with those obtained by a comparison method. Both methods were utilized to investigate the kinetics of the degradation of the drug. PMID:21385439

  18. Temporal indications of atmospheric stability affecting off-target spray drift in the midsouth U S

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was designed to determine atmospheric conditions favorable for long-distance spray drift deleterious to susceptible crops. A tall meteorological monitoring tower equipped with six precision (and periodically calibrated) thermistors at six heights to 27.4 m and wind speed anemometers at fo...

  19. EXAMINING THE EFFECTS OF URBANIZATION ON STREAMS USING INDICATORS OF GEOMORPHIC STABILITY. (R825871)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  20. A stability indicating HPLC method for the determination of clobazam and its basic degradation product characterization

    PubMed Central

    2014-01-01

    Background Clobazam is used for the treatment of different types of seizure and epilepsy. The present research is undertaken to study the systematic forced degradation of clobazam and to identify its main degradation product under basic conditions. Methods The degradation of clobazam was studied under different conditions. Clobazam and its degradation products were separated using a Nova-Pak C18 column and a mixture of KH2PO4 50 mM (pH 8.5) and acetonitrile (50:50, v/v) as the mobile phase with UV detection at 230 nm. Results The within-day and between-day precision values in the calibration range of 0.1-20 ?g/ml were within 0.5-1.5%. Clobazam was relatively stable in solid from under exposure to visible and UV light and also heat. The clobazam aqueous solution of clobazam was more labile under exposure to visible and UV light. The bulk drug was significantly degraded under exposure to 2 M HCl, 0.1 M NaOH or 3% H2O2. Using the tablet powder, higher degradation rates were observed under different stress conditions. The main degradation product of clobazam under basic condition was subsequently characterized. Conclusion The developed method could be used for the determination of clobazam in the presence of its degradation products with acceptable precision and accuracy. The applicability of the proposed method was evaluated in commercial dosage forms analysis. PMID:24919821

  1. Long-term stability of crystal-stabilized water-in-oil emulsions.

    PubMed

    Ghosh, Supratim; Pradhan, Mamata; Patel, Tejas; Haj-Shafiei, Samira; Rousseau, Dérick

    2015-12-15

    The impact of cooling rate and mixing on the long-term kinetic stability of wax-stabilized water-in-oil emulsions was investigated. Four cooling/mixing protocols were investigated: cooling from 45°C to either 25°C or 4°C with/without stirring and two cooling rates - slow (1°C/min) and fast (5°C/min). The sedimentation behaviour of the emulsions was significantly affected by cooling protocol. Stirring was critical to the stability of all emulsions, with statically-cooled (no stirring) emulsions suffering from extensive aqueous phase separation. Emulsions stirred while cooling showed sedimentation of a waxy emulsion layer leaving a clear oil layer at the top, with a smaller separation and droplet size distribution at 4°C compared to 25°C, indicating the importance of the amount of crystallized wax on emulsion stability. Light microscopy revealed that crystallized wax appeared both on the droplet surface and in the continuous phase, suggesting that stirring ensured dispersibility of the water droplets during cooling as the wax was crystallizing. Wax crystallization on the droplet surface provided stability against droplet coalescence while continuous phase wax crystals minimized inter-droplet collisions. The key novel aspect of this research is in the simplicity to tailor the spatial distribution of wax crystals, i.e., either at the droplet surface or in the continuous phase via use of a surfactant and judicious stirring and/or cooling. Knowledge gained from this research can be applied to develop strategies for long-term storage stability of crystal-stabilized W/O emulsions. PMID:26343977

  2. MCH indicators in south Asia.

    PubMed

    Ramji, S

    1997-05-01

    This article presents some statistical indicators of maternal and child health in countries of South Asia, including Afghanistan, Bangladesh, Bhutan, India, Nepal, Pakistan, and Sri Lanka. Statistical tables aggregate data for the entire South Asia region and industrialized countries, for comparative purposes. South Asia has about 22% of world population, 33% of births annually, about 37% of annual global child mortality (CM), and the second highest maternal mortality ratio (MMR). In 1995, Sri Lanka had the lowest CM. Afghanistan had the highest CM. CM in the region was 121, or 15 times more than in industrialized countries. Countries with higher CM rates tended to have higher birthrates. Total fertility rates ranged from 2.4 in Sri Lanka, to 6.6 in Afghanistan. The total fertility rate in the region was 3.9. 29% of births in the region were attended by a trained attendant during 1990-96. Under 10% of births were attended by a trained attendant in Nepal (7%) and Afghanistan (9%). India had the highest proportion of births attended by a trained attendant (34%). Contraceptive prevalence ranged from a low of 2% in Afghanistan, to a high of 66% in Sri Lanka. Contraceptive prevalence for the region was 38%. Female literacy was lowest in Nepal (14%) and Afghanistan (15%). Sri Lanka had the highest female literacy of 87%, followed by India with 38%. Female literacy for the region was 36%. Countries with high fertility rates tended to have high MMRs. MMR was inversely related to contraceptive prevalence rates, presence of trained attendants during delivery, and adult female literacy rates. 90% of the region had coverage with BCG immunization, followed by DPT, OPV, and measles immunization. Maternal tetanus toxoid was 69%. PMID:9332117

  3. Hydrogen sulfide measurement using sulfide dibimane: critical evaluation with electrospray ion trap mass spectrometry

    PubMed Central

    Shen, Xinggui; Chakraborty, Sourav; Dugas, Tammy R; Kevil, Christopher G

    2015-01-01

    Accurate measurement of hydrogen sulfide bioavailability remains a technical challenge due to numerous issues involving sample processing, detection methods used, and actual biochemical products measured. Our group and others have reported that reverse phase HPLC detection of sulfide dibimane (SDB) product from the reaction of H2S/HS? with monobromobimane allows for analytical detection of hydrogen sulfide bioavailability in free and other biochemical forms. However, it remains unclear whether possible interfering contaminants may contribute to HPLC SDB peak readings that may result in inaccurate measurements of bioavailable sulfide. In this study, we critically compared hydrogen sulfide dependent SDB detection using reverse phase HPLC (RP-HPLC) versus quantitative SRM electrospray ionization mass spectrometry (ESI/MS) to obtain greater clarity into the validity of the reverse phase HPLC method for analytical measurement of hydrogen sulfide. Using an LCQ-deca ion-trap mass spectrometer, SDB was identified by ESI/MS positive ion mode, and quantified by selected reaction monitoring (SRM) using hydrocortisone as an internal standard. Collision induced dissociation (CID) parameters were optimized at MS2 level for SDB and hydrocortisone. ESI/MS detection of SDB standard was found to be a log order more sensitive than RP-HPLC with a lower limit of 0.25 nM. Direct comparison of tissue and plasma SDB levels using RP-HPLC and ESI/MS methods revealed comparable sulfide levels in plasma, aorta, heart, lung and brain. Together, these data confirm the use of SDB as valid indicator of H2S bioavailability and highlights differences between analytical detection methods. PMID:24932544

  4. Hydrogen sulfide measurement using sulfide dibimane: critical evaluation with electrospray ion trap mass spectrometry.

    PubMed

    Shen, Xinggui; Chakraborty, Sourav; Dugas, Tammy R; Kevil, Christopher G

    2014-09-15

    Accurate measurement of hydrogen sulfide bioavailability remains a technical challenge due to numerous issues involving sample processing, detection methods used, and actual biochemical products measured. Our group and others have reported that reverse phase HPLC detection of sulfide dibimane (SDB) product from the reaction of H2S/HS(-) with monobromobimane allows for analytical detection of hydrogen sulfide bioavailability in free and other biochemical forms. However, it remains unclear whether possible interfering contaminants may contribute to HPLC SDB peak readings that may result in inaccurate measurements of bioavailable sulfide. In this study, we critically compared hydrogen sulfide dependent SDB detection using reverse phase HPLC (RP-HPLC) versus quantitative SRM electrospray ionization mass spectrometry (ESI/MS) to obtain greater clarity into the validity of the reverse phase HPLC method for analytical measurement of hydrogen sulfide. Using an LCQ-Deca ion-trap mass spectrometer, SDB was identified by ESI/MS positive ion mode, and quantified by selected reaction monitoring (SRM) using hydrocortisone as an internal standard. Collision induced dissociation (CID) parameters were optimized at MS2 level for SDB and hydrocortisone. ESI/MS detection of SDB standard was found to be a log order more sensitive than RP-HPLC with a lower limit of 0.25 nM. Direct comparison of tissue and plasma SDB levels using RP-HPLC and ESI/MS methods revealed comparable sulfide levels in plasma, aorta, heart, lung and brain. Together, these data confirm the use of SDB as valid indicator of H2S bioavailability and highlights differences between analytical detection methods. PMID:24932544

  5. Rangeland health attributes and indicators for qualitative assessment

    USGS Publications Warehouse

    Pyke, David A.; Herrick, J.E.; Pellant, Mike

    2002-01-01

    Panels of experts from the Society for Range Management and the National Research Council proposed that status of rangeland ecosystems could be ascertained by evaluating an ecological site's potential to conserve soil resources and by a series of indicators for ecosystem processes and site stability. Using these recommendations as a starting point, we developed a rapid, qualitative method for assessing a moment-in-time status of rangelands. Evaluators rate 17 indicators to assess 3 ecosystem attributes (soil and site stability, hydrologic function, and biotic integrity) for a given location. Indicators include rills, water flow patterns, pedestals and terracettes, bare ground, gullies, wind scour and depositional areas, litter movement, soil resistance to erosion, soil surface loss or degradation, plant composition relative to infiltration, soil compaction, plant functional/structural groups, plant mortality, litter amount, annual production, invasive plants, and reproductive capability. In this paper, we detail the development and evolution of the technique and introduce a modified ecological reference worksheet that documents the expected presence and amount of each indicator on the ecological site. In addition, we review the intended applications for this technique and clarify the differences between assessment and monitoring that lead us to recommend this technique be used for moment-in-time assessments and not be used for temporal monitoring of rangeland status. Lastly, we propose a mechanism for adapting and modifying this technique to reflect improvements in understanding of ecosystem processes. We support the need for quantitative measures for monitoring rangeland health and propose some measures that we believe may address some of the 17 indicators.

  6. 14 CFR 23.181 - Dynamic stability.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 false Dynamic stability. 23.181 Section... Stability § 23.181 Dynamic stability. (a) Any...of a stability augmentation system, reference § 23.672...verify the acceptability of that system. (d) During...

  7. 14 CFR 23.181 - Dynamic stability.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 2011-01-01 false Dynamic stability. 23.181 Section... Stability § 23.181 Dynamic stability. (a) Any...of a stability augmentation system, reference § 23.672...verify the acceptability of that system. (d) During...

  8. 14 CFR 23.181 - Dynamic stability.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 false Dynamic stability. 23.181 Section... Stability § 23.181 Dynamic stability. (a) Any...of a stability augmentation system, reference § 23.672...verify the acceptability of that system. (d) During...

  9. 14 CFR 23.181 - Dynamic stability.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 2010-01-01 false Dynamic stability. 23.181 Section... Stability § 23.181 Dynamic stability. (a) Any...of a stability augmentation system, reference § 23.672...verify the acceptability of that system. (d) During...

  10. Geometric stability of topological lattice phases

    NASA Astrophysics Data System (ADS)

    Jackson, T. S.; Möller, Gunnar; Roy, Rahul

    2015-11-01

    The fractional quantum Hall (FQH) effect illustrates the range of novel phenomena which can arise in a topologically ordered state in the presence of strong interactions. The possibility of realizing FQH-like phases in models with strong lattice effects has attracted intense interest as a more experimentally accessible venue for FQH phenomena which calls for more theoretical attention. Here we investigate the physical relevance of previously derived geometric conditions which quantify deviations from the Landau level physics of the FQHE. We conduct extensive numerical many-body simulations on several lattice models, obtaining new theoretical results in the process, and find remarkable correlation between these conditions and the many-body gap. These results indicate which physical factors are most relevant for the stability of FQH-like phases, a paradigm we refer to as the geometric stability hypothesis, and provide easily implementable guidelines for obtaining robust FQH-like phases in numerical or real-world experiments.

  11. Cooperative Gold Nanoparticle Stabilization by Acetylenic Phosphaalkenes

    PubMed Central

    Orthaber, Andreas; Löfås, Henrik; Öberg, Elisabet; Grigoriev, Anton; Wallner, Andreas; Jafri, S Hassan M; Santoni, Marie-Pierre; Ahuja, Rajeev; Leifer, Klaus; Ottosson, Henrik; Ott, Sascha

    2015-01-01

    Acetylenic phosphaalkenes (APAs) are used as a novel type of ligands for the stabilization of gold nanoparticles (AuNP). As demonstrated by a variety of experimental and analytical methods, both structural features of the APA, that is, the P=C as well as the C?C units are essential for NP stabilization. The presence of intact APAs on the AuNP is demonstrated by surface-enhanced Raman spectroscopy (SERS), and first principle calculations indicate that bonding occurs most likely at defect sites on the Au surface. AuNP-bound APAs are in chemical equilibrium with free APAs in solution, leading to a dynamic behavior that can be explored for facile place-exchange reactions with other types of anchor groups such as thiols or more weakly binding phosphine ligands. PMID:26211907

  12. Stability threshold approach for complex dynamical systems

    NASA Astrophysics Data System (ADS)

    Klinshov, Vladimir V.; Nekorkin, Vladimir I.; Kurths, Jürgen

    2016-01-01

    A new measure to characterize the stability of complex dynamical systems against large perturbations is suggested, the stability threshold (ST). It quantifies the magnitude of the weakest perturbation capable of disrupting the system and switch it to an undesired dynamical regime. In the phase space, the ST corresponds to the 'thinnest site' of the attraction basin and therefore indicates the most 'dangerous' direction of perturbations. We introduce a computational algorithm for quantification of the ST and demonstrate that the suggested approach is effective and provides important insights. The generality of the obtained results defines their vast potential for application in such fields as engineering, neuroscience, power grids, Earth science and many others where the robustness of complex systems is studied.

  13. Geometric stability of topological lattice phases.

    PubMed

    Jackson, T S; Möller, Gunnar; Roy, Rahul

    2015-01-01

    The fractional quantum Hall (FQH) effect illustrates the range of novel phenomena which can arise in a topologically ordered state in the presence of strong interactions. The possibility of realizing FQH-like phases in models with strong lattice effects has attracted intense interest as a more experimentally accessible venue for FQH phenomena which calls for more theoretical attention. Here we investigate the physical relevance of previously derived geometric conditions which quantify deviations from the Landau level physics of the FQHE. We conduct extensive numerical many-body simulations on several lattice models, obtaining new theoretical results in the process, and find remarkable correlation between these conditions and the many-body gap. These results indicate which physical factors are most relevant for the stability of FQH-like phases, a paradigm we refer to as the geometric stability hypothesis, and provide easily implementable guidelines for obtaining robust FQH-like phases in numerical or real-world experiments. PMID:26530311

  14. On stability and turbulence of fluid flows

    NASA Technical Reports Server (NTRS)

    Heisenberg, Werner

    1951-01-01

    This investigation is divided into two parts, the treatment of the stability problem of fluid flows on the one hand, and that of the turbulent motion on the other. The first part summarizes all previous investigations under a unified point of view, that is, sets up as generally as possible the conditions under which a profile possesses unstable or stable characteristics, and indicates the methods for solution of the stability equation for any arbitrary velocity profile and for calculation of the critical Reynolds number for unstable profiles. In the second part, under certain greatly idealizing assumptions, differential equations for the turbulent motions are derived and from them qualitative information about several properties of the turbulent velocity distribution is obtained.

  15. Geometric stability of topological lattice phases

    PubMed Central

    Jackson, T. S.; Möller, Gunnar; Roy, Rahul

    2015-01-01

    The fractional quantum Hall (FQH) effect illustrates the range of novel phenomena which can arise in a topologically ordered state in the presence of strong interactions. The possibility of realizing FQH-like phases in models with strong lattice effects has attracted intense interest as a more experimentally accessible venue for FQH phenomena which calls for more theoretical attention. Here we investigate the physical relevance of previously derived geometric conditions which quantify deviations from the Landau level physics of the FQHE. We conduct extensive numerical many-body simulations on several lattice models, obtaining new theoretical results in the process, and find remarkable correlation between these conditions and the many-body gap. These results indicate which physical factors are most relevant for the stability of FQH-like phases, a paradigm we refer to as the geometric stability hypothesis, and provide easily implementable guidelines for obtaining robust FQH-like phases in numerical or real-world experiments. PMID:26530311

  16. The Resource Theory of Stabilizer Computation

    E-print Network

    Victor Veitch; Seyed Ali Hamed Mousavian; Daniel Gottesman; Joseph Emerson

    2013-07-26

    Recent results on the non-universality of fault-tolerant gate sets underline the critical role of resource states, such as magic states, to power scalable, universal quantum computation. Here we develop a resource theory, analogous to the theory of entanglement, for resources for stabilizer codes. We introduce two quantitative measures - monotones - for the amount of non-stabilizer resource. As an application we give absolute bounds on the efficiency of magic state distillation. One of these monotones is the sum of the negative entries of the discrete Wigner representation of a quantum state, thereby resolving a long-standing open question of whether the degree of negativity in a quasi-probability representation is an operationally meaningful indicator of quantum behaviour.

  17. Stabilizing synchrony by inhomogeneity.

    PubMed

    Bolhasani, Ehsan; Valizadeh, Alireza

    2015-01-01

    We show that for two weakly coupled identical neuronal oscillators with strictly positive phase resetting curve, isochronous synchrony can only be seen in the absence of noise and an arbitrarily weak noise can destroy entrainment and generate intermittent phase slips. Small inhomogeneity-mismatch in the intrinsic firing rate of the neurons-can stabilize the phase locking and lead to more precise relative spike timing of the two neurons. The results can explain how for a class of neuronal models, including leaky integrate-fire model, inhomogeneity can increase correlation of spike trains when the neurons are synaptically connected. PMID:26338691

  18. Stabilizing synchrony by inhomogeneity

    PubMed Central

    Bolhasani, Ehsan; Valizadeh, Alireza

    2015-01-01

    We show that for two weakly coupled identical neuronal oscillators with strictly positive phase resetting curve, isochronous synchrony can only be seen in the absence of noise and an arbitrarily weak noise can destroy entrainment and generate intermittent phase slips. Small inhomogeneity–mismatch in the intrinsic firing rate of the neurons–can stabilize the phase locking and lead to more precise relative spike timing of the two neurons. The results can explain how for a class of neuronal models, including leaky integrate-fire model, inhomogeneity can increase correlation of spike trains when the neurons are synaptically connected. PMID:26338691

  19. Chassis stabilization system

    DOEpatents

    Claxton, Gerald L. (Fresno, CA)

    1999-01-01

    A stabilizing suspension system is provided for vehicles carrying telescopic booms or aerial work platforms having a fixed axle and a oscillating axle. Hydraulic cylinders are connected to each end of the oscillating axle, each cylinder being capable of extending and retracting. An off level sensor senses the angle of tilt of the chassis in both left and right directions and, when a predetermined threshold of tilt has been detected, the hydraulic cylinder on the downhill side of the chassis is locked against retracting, but is free to move in the downhill direction to allow the downhill wheel to remain in contact with the ground.

  20. Foams Stabilized by Tricationic Amphiphilic Surfactants

    E-print Network

    Seth Heerschap; John N. Marafino; Kristin McKenna; Kevin L. Caran; Klebert Feitosa

    2015-09-11

    The unique surface properties of amphiphilic molecules have made them widely used in applications where foaming, emulsifying or coating processes are needed. Novel surfactant architectures with multi-cephalic and multi-tailed molecules have reportedly enhanced their anti-bacterial activity in connection with tail length and the nature of the head group, but their ability to produce and stabilize foam is mostly unknown. Here we report on experiments with tris-cationic, triple-headed, double- and single-tailed amphiphiles and their foamability and foam stability with respect to head group, tail number and tail length. The amphiphiles are composed of an aromatic mesitylene core and three benzylic amonium bromide groups, with alkyl chains attached to one or two of the head groups. Whereas shorter (14 carbons in length) double-tailed molecules are found to produce very stable foams, foams made with single tail molecules of the same length show poor foamability and stability, and foams with longer (16 carbons in length) double-tail molecules do not foam with the methods used. By contrast, the structure of the non-tail-bearing head group (trimethylammonium vs. pyridinium) has no impact on foamability. Furthermore, observations of the coarsening rate at nearly constant liquid content indicate that the enhanced foam stability is a result of lower gas permeability through the surfactant monolayer. Finally, the critical aggregation concentration (CAC) of the surfactants demonstrates to be a good predictor of foamability and foam stability for these small molecule surfactants. This results inform how surfactant architecture can be tailored to produce stable foams.

  1. Purification and characterization of a hyaluronidase from venom of the spider Vitalius dubius (Araneae, Theraphosidae)

    PubMed Central

    2014-01-01

    Background Venom hyaluronidase (Hyase) contributes to the diffusion of venom from the inoculation site. In this work, we purified and characterized Hyase from the venom of Vitalius dubius (Araneae, Theraphosidae), a large theraphosid found in southeastern Brazil. Venom obtained by electrical stimulation of adult male and female V. dubius was initially fractionated by gel filtration on a Superdex® 75 column. Active fractions were pooled and applied to a heparin-sepharose affinity column. The proteins were eluted with a linear NaCl gradient. Results Active fractions were pooled and assessed for purity by SDS-PAGE and RP-HPLC. The physicochemical tests included optimum pH, heat stability, presence of isoforms, neutralization by flavonoids and assessment of commercial antivenoms. Hyase was purified and presented a specific activity of 148 turbidity-reducing units (TRU)/mg (venom: 36 TRU/mg; purification factor of ~4). Hyase displayed a molecular mass of 43 kDa by SDS-PAGE. Zymography in hyaluronic-acid-containing gels indicated an absence of enzyme isoforms. The optimum pH was 4-5, with highest activity at 37°C. Hyase was stable up to 60°C; but its activity was lost at higher temperatures and maintained after several freeze-thaw cycles. The NaCl concentration (up to 1 M) did not influence activity. Hyase had greater action towards hyaluronic acid compared to chondroitin sulfate, and was completely neutralized by polyvalent antiarachnid sera, but not by caterpillar, scorpion or snakes antivenoms. Conclusion The neutralization by arachnid but not scorpion antivenom indicates that this enzyme shares antigenic epitopes with similar enzymes in other spider venoms. The biochemical properties of this Hyase are comparable to others described. PMID:24495716

  2. PROGRAMME GROUP RESEARCH UPDATE: Biodiversity indicators &

    E-print Network

    1 PROGRAMME GROUP RESEARCH UPDATE: Biodiversity indicators & knowledge management programme group Introduction Duncan Ray The programme group Biodiversity Indicators and Knowledge Management (BIKM) was established by the merger of the Biodiversity Indicators & Evaluation Programme and the Decision Support

  3. SAMPEX Spin Stabilized Mode

    NASA Technical Reports Server (NTRS)

    Tsai, Dean C.; Markley, F. Landis; Watson, Todd P.

    2008-01-01

    The Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX), the first of the Small Explorer series of spacecraft, was launched on July 3, 1992 into an 82' inclination orbit with an apogee of 670 km and a perigee of 520 km and a mission lifetime goal of 3 years. After more than 15 years of continuous operation, the reaction wheel began to fail on August 18,2007. With a set of three magnetic torquer bars being the only remaining attitude actuator, the SAMPEX recovery team decided to deviate from its original attitude control system design and put the spacecraft into a spin stabilized mode. The necessary operations had not been used for many years, which posed a challenge. However, on September 25, 2007, the spacecraft was successfully spun up to 1.0 rpm about its pitch axis, which points at the sun. This paper describes the diagnosis of the anomaly, the analysis of flight data, the simulation of the spacecraft dynamics, and the procedures used to recover the spacecraft to spin stabilized mode.

  4. Stability of cooled beams

    NASA Astrophysics Data System (ADS)

    Bosser, J.; Carli, C.; Chanel, M.; Madsen, N.; Maury, S.; Möhl, D.; Tranquille, G.

    2000-02-01

    Because of their high density together with extremely small spreads in betatron frequency and momentum, cooled beams are very vulnerable to incoherent and coherent space-charge effects and instabilities. Moreover, the cooling system itself, i.e. the electron beam in the case of e-cooling, presents large linear and non-linear "impedances" to the circulating ion beam, in addition to the usual beam-environment coupling impedances of the storage ring. Beam blow-up and losses, attributed to such effects, have been observed in virtually all the existing electron cooling rings. The adverse effects seem to be more pronounced in those rings, like CELSIUS, that are equipped with a cooler capable of reaching the presently highest energy (100-300 keV electrons corresponding to 180-560 MeV protons). The stability conditions will be revisited with emphasis on the experience gained at LEAR. It will be argued that for all present coolers, three conditions are necessary (although probably not sufficient) for the stability of intense cold beams: (i) operation below transition energy, (ii) active damping to counteract coherent instability, and (iii) careful control of the e-beam neutralisation. An extrapolation to the future "medium energy coolers", planned to work for (anti)protons of several GeV, will also be attempted.

  5. Stabilization of graphene nanopore

    PubMed Central

    Lee, Jaekwang; Yang, Zhiqing; Zhou, Wu; Pennycook, Stephen J.; Pantelides, Sokrates T.; Chisholm, Matthew F.

    2014-01-01

    Graphene is an ultrathin, impervious membrane. The controlled introduction of nanoscale pores in graphene would lead to applications that involve water purification, chemical separation, and DNA sequencing. However, graphene nanopores are unstable against filling by carbon adatoms. Here, using aberration-corrected scanning transmission electron microscopy and density-functional calculations, we report that Si atoms stabilize graphene nanopores by bridging the dangling bonds around the perimeter of the hole. Si?passivated pores remain intact even under intense electron beam irradiation, and they were observed several months after the sample fabrication, demonstrating that these structures are intrinsically robust and stable against carbon filling. Theoretical calculations reveal the underlying mechanism for this stabilization effect: Si atoms bond strongly to the graphene edge, and their preference for tetrahedral coordination forces C adatoms to form dendrites sticking out of the graphene plane, instead of filling the nanopore. Our results provide a novel way to develop stable nanopores, which is a major step toward reliable graphene-based molecular translocation devices. PMID:24821802

  6. Stabilization of graphene nanopore

    SciTech Connect

    Lee, Jaekwang; Yang, Zhiqing; Zhou, Wu; Pennycook, Stephen J.; Pantelides, Sokrates T.; Chisholm, Matthew F.

    2014-05-27

    Graphene is an ultrathin, impervious membrane. The controlled introduction of nanoscale pores in graphene would lead to applications that involve water purification, chemical separation, and DNA sequencing. However, graphene nanopores are unstable against filling by carbon adatoms. Using aberration-corrected scanning transmission electron microscopy and density-functional calculations, we report that Si atoms stabilize graphene nanopores by bridging the dangling bonds around the perimeter of the hole. Si-passivated pores remain intact even under intense electron beam irradiation, and they were observed several months after the sample fabrication, demonstrating that these structures are intrinsically robust and stable against carbon filling. Theoretical calculations reveal the underlying mechanism for this stabilization effect: Si atoms bond strongly to the graphene edge, and their preference for tetrahedral coordination forces C adatoms to form dendrites sticking out of the graphene plane, instead of filling the nanopore. Our results provide a novel way to develop stable nanopores, which is a major step toward reliable graphene-based molecular translocation devices.

  7. Stability of phantom wormholes

    SciTech Connect

    Lobo, Francisco S.N.

    2005-06-15

    It has recently been shown that traversable wormholes may be supported by phantom energy. In this work phantom wormhole geometries are modeled by matching an interior traversable wormhole solution, governed by the equation of state p={omega}{rho} with {omega}<-1, to an exterior vacuum spacetime at a finite junction interface. The stability analysis of these phantom wormholes to linearized spherically symmetric perturbations about static equilibrium solutions is carried out. A master equation dictating the stability regions is deduced, and by separating the cases of a positive and a negative surface energy density, it is found that the respective stable equilibrium configurations may be increased by strategically varying the wormhole throat radius. The first model considered, in the absence of a thin shell, is that of an asymptotically flat phantom wormhole spacetime. The second model constructed is that of an isotropic pressure phantom wormhole, which is of particular interest, as the notion of phantom energy is that of a spatially homogeneous cosmic fluid, although it may be extended to inhomogeneous spherically symmetric spacetimes.

  8. 49 CFR 230.68 - Speed indicators.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Speed Indicators § 230.68 Speed indicators. Steam locomotives that operate at speeds in excess...

  9. 49 CFR 230.68 - Speed indicators.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Speed Indicators § 230.68 Speed indicators. Steam locomotives that operate at speeds in excess...

  10. 49 CFR 230.68 - Speed indicators.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Speed Indicators § 230.68 Speed indicators. Steam locomotives that operate at speeds in excess...

  11. 49 CFR 230.68 - Speed indicators.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Speed Indicators § 230.68 Speed indicators. Steam locomotives that operate at speeds in excess...

  12. 49 CFR 230.68 - Speed indicators.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Steam Locomotives and Tenders Speed Indicators § 230.68 Speed indicators. Steam locomotives that operate at speeds in excess...

  13. The Signature of Life in Stabilized Dune Topography

    NASA Astrophysics Data System (ADS)

    Barchyn, T. E.; Hugenholtz, C.

    2012-12-01

    Life dramatically affects aeolian dunes on Earth by modifying dune morphology and immobilizing sediment. Complete immobilization (stabilization) occurs when vegetation growth shelters the surface and eliminates sediment transport (and the capacity of the dune to clear vegetation). In unidirectional dune forms stabilization is usually preceded by a period of transition dominated by pronounced morphological change (e.g., parabolic dunes). Here, we hypothesize that stabilized topography holds previously unidentified clues detailing the kinematics and behavior of vegetation during stabilization (a 'signature'). During stabilization dune ridges advance downwind and 'bulldoze' vegetation in their path. We split dune ridges into a series of wind-parallel 'dune slices' and outline how slipface vegetation could prove to be a 'tipping point' in stabilization for each dune slice. Slipface vegetation sets off a self-reinforcing stabilization feedback, simplifying our treatment and yielding two predictable behaviors: slipfaces either clear vegetation (deposition rate > vegetation deposition tolerance), or succumb to vegetation and become immobilized (deposition rate < vegetation deposition tolerance). We model slipface deposition rates through slipface geometry and show how predictable variations in classical dune forms (i) could be responsible for incipient transformation of barchan to parabolic dunes, (ii) result in a progressive stabilization feedback fundamentally inconsistent with widely used dune activity indices, and (iii) record a quantitative signature of the relative kinematics of sediment flux and vegetation growth in stabilized slipface geometries. To explore the idea in real dune fields, we extract slipface deposition rates through slipface geometry recorded in digital terrain data for three dune fields: (i) Bigstick Sand Hills, SK, Canada, (ii) White Sands, NM, USA, and (iii) Cape Cod, MA, USA. With independent estimates of sediment flux and vegetation deposition tolerance we show how all three dune fields show consistent results with characteristic deposition rates approximately 60% of vegetation deposition tolerance. These results open the possibility that a consistent and identifiable 'signature of life' could be coded into all stabilized dune topography worldwide.

  14. Backstepping design for incremental stability

    E-print Network

    Zamani, Majid

    2010-01-01

    Stability is arguably one of the core concepts upon which our understanding of dynamical and control systems has been built. The related notion of incremental stability, however, has received much less attention until recently, when it was successfully used as a tool for the analysis and design of intrinsic observers, output regulation of nonlinear systems, frequency estimators, synchronization of coupled identical dynamical systems, symbolic models for nonlinear control systems, and bio-molecular systems. However, most of the existing controller design techniques provide controllers enforcing stability rather than incremental stability. Hence, there is a growing need to extend existing methods or develop new ones for the purpose of designing incrementally stabilizing controllers. In this paper, we develop a backstepping design approach for incremental stability. The effectiveness of the proposed method is illustrated by synthesizing a controller rendering a synchronous generator incrementally stable.

  15. New image-stabilizing system

    NASA Astrophysics Data System (ADS)

    Zhao, Yuejin

    1996-06-01

    In this paper, a new method for image stabilization with a three-axis image- stabilizing reflecting prism assembly is presented, and the principle of image stabilization in this prism assembly, formulae for image stabilization and working formulae with an approximation up to the third power are given in detail. In this image-stabilizing system, a single chip microcomputer is used to calculate value of compensating angles and thus to control the prism assembly. Two gyroscopes act as sensors from which information of angular perturbation is obtained, three stepping motors drive the prism assembly to compensate for the movement of image produced by angular perturbation. The image-stabilizing device so established is a multifold system which involves optics, mechanics, electronics and computer.

  16. Superconductor stability 90: A review

    SciTech Connect

    Dresner, L.

    1990-01-01

    This paper reviews some recent developments in the field of stability of superconductors. The main topics dealt with are hydrodynamic phenomena in cable-in-conduit superconductors, namely, multiple stability, quench pressure, thermal expulsion, and thermal hydraulic quenchback, traveling normal zones in large, composite conductors, such as those intended for SMES, and the stability of vapor-cooled leads made of high-temperature superconductors. 31 refs., 5 figs.

  17. Stability versus Optimality

    NASA Astrophysics Data System (ADS)

    Inanloo, B.

    2011-12-01

    The Caspian Sea is considered to be the largest inland body of water in the world, which located between the Caucasus Mountains and Central Asia. The Caspian Sea has been a source of the most contentious international conflicts between five littoral states now borders the sea: Azerbaijan, Iran, Kazakhstan, Russia, and Turkmenistan. The conflict over the legal status of this international body of water as an aftermath of the breakup of the Soviet Union in 1991. Since then the parties have been negotiating without coming up with any agreement neither on the ownerships of waters, nor the oil and natural gas beneath them. The number of involved stakeholders, the unusual characteristics of the Caspian Sea in considering it as a lake or a sea, and a large number of external parties are interested in the valuable resources of the Sea has made this conflict complex and unique. This paper intends to apply methods to find the best allocation schemes considering acceptability and stability of selected solution to share the Caspian Sea and its resources fairly and efficiently. Although, there are several allocation methods in solving such allocation problems, however, most of those seek a socially optimal solution that can satisfy majority of criteria or decision makers, while, in practice, especially in multi-nation problems, such solution may not be necessarily a stable solution and to be acceptable to all parties. Hence, there is need to apply a method that considers stability and acceptability of solutions to find a solution with high chance to be agreed upon that. Application of some distance-based methods in studying the Caspian Sea conflict provides some policy insights useful for finding solutions that can resolve the dispute. In this study, we use methods such as Goal Programming, Compromise Programming, and considering stability of solution the logic of Power Index is used to find a division rule that is stable negotiators. The results of this study shows that the final approved allocation scheme may not be the same as the results of previous studies which focused on the Caspian Sea conflict resolution which all found an socially optimal solution instead of stable one.

  18. ASSESSMENT OF CHANNEL STABILITY AT BRIDGE SITES.

    USGS Publications Warehouse

    Brice, James C.

    1984-01-01

    Assessment of channel stability from field study and the comparison of time-sequential aerial photographs provides information that is needed in site selection, bridge design, and countermeasure placement. Channel instability is indicated by bank erosion, progressive degradation (or aggradation) of the streambed, or natural scour and fill of the streambed. Bank erosion rates are related to stream type and are proportional to stream size. Predictions of future rates are based on past rates, as measured on time-sequential photographs or mps, and on the typical behavior of meander loops.

  19. Understanding nanofluid stability through molecular simulation

    NASA Astrophysics Data System (ADS)

    Dang, Liem X.; Annapureddy, Harsha V. R.; Sun, Xiuquan; Thallapally, Praveen K.; Peter McGrail, B.

    2012-11-01

    Molecular dynamics simulations were carried out to systematically study solvation and nanoparticle-particle interactions in n-hexane, water and methanol solvents. The dynamics of the n-hexane molecules was significantly influenced by the solvated nanoparticles. Water and methanol show significant structural signatures binding to the metal coordination sites of the nanoparticles while liquid hexane does not. The computed free energy profiles illustrate that the associations between nanoparticles in solution are stable and depend on the relative orientation of them. Also, these profiles indicate a low interaction potential between nanoparticles in methanol, confirming experimental observations of inherent nanofluid stability without need for added surfactant.

  20. Sensitivity analysis of hydrodynamic stability operators

    NASA Technical Reports Server (NTRS)

    Schmid, Peter J.; Henningson, Dan S.; Khorrami, Mehdi R.; Malik, Mujeeb R.

    1992-01-01

    The eigenvalue sensitivity for hydrodynamic stability operators is investigated. Classical matrix perturbation techniques as well as the concept of epsilon-pseudoeigenvalues are applied to show that parts of the spectrum are highly sensitive to small perturbations. Applications are drawn from incompressible plane Couette, trailing line vortex flow and compressible Blasius boundary layer flow. Parametric studies indicate a monotonically increasing effect of the Reynolds number on the sensitivity. The phenomenon of eigenvalue sensitivity is due to the non-normality of the operators and their discrete matrix analogs and may be associated with large transient growth of the corresponding initial value problem.

  1. Aerodynamic Drag and Gyroscopic Stability

    E-print Network

    Elya R. Courtney; Michael W. Courtney

    2014-10-16

    This paper describes the effects on aerodynamic drag of rifle bullets as the gyroscopic stability is lowered from 1.3 to 1.0. It is well known that a bullet can tumble for stability less than 1.0. The Sierra Loading Manuals (4th and 5th Editions) have previously reported that ballistic coefficient decreases significantly as gyroscopic stability, Sg, is lowered below 1.3. These observations are further confirmed by experiments reported here. Measured ballistic coefficients were compared with gyroscopic stabilities computed using the Miller Twist Rule for nearly solid metal bullets with uniform density and computed using the Courtney-Miller formula for plastic-tipped bullets. The relationship between Sg and drag may be used to test the applicability of existing gyroscopic stability formulas for given bullet designs and to evaluate the accuracy of alternate formulas in cases where the existing stability formulas are not as accurate. The most definitive test of formulas predicting stability will always be observation of whether bullets tumble under given conditions. However, observations of drag changes provide valuable supplemental information because they suggest changes in stability as conditions change. Use of a continuous variable (drag) rather than a binary variable (tumbling) allows insight into stability over a range of conditions where the binary variable does not change.

  2. Wall stabilization and the Mathieu-Hill equations

    NASA Astrophysics Data System (ADS)

    Tasso, H.; Throumoulopoulos, G. N.

    2002-06-01

    In a recent publication [H. Tasso and G. N. Throumoulopoulos, Phys. Lett. A 271, 413 (2000)] on Lyapunov stability of general mechanical systems, it is shown that "parametric excitations" can be stabilized by dissipation for positive potential energies. Specializing on the damped Mathieu equation permits one to establish its full stability chart. It is then seen that dissipation broadens the regions of stability to the extent that not only the response to parametric excitations is damped, but even "negative-energy" modes are stabilized by the combined action of the parametric excitation and the damping coefficient. The extension of this analysis to the "two-step" Hill's equation shows that the stability regions become many times larger than those of the Mathieu equation. By analogy, these findings are a strong indication that the "resistive wall mode" could be stabilized by the joint action of a properly tailored time-dependent wall resistivity and a sufficient viscous dissipation in the plasma. Note that within this scheme neither the wall nor the plasma need to be in motion. An extension of this work to include more realistic models is in progress.

  3. Wall Stabilization and the Mathieu-Hill Equations.

    NASA Astrophysics Data System (ADS)

    Tasso, Henri; Throumoulopoulos, George N.

    2001-10-01

    In a recent publication (see [1]) on Lyapunov stability of general mechanical systems, it is shown that "parametric excitations" can be stabilized by dissipation for positive potential energies. Specializing on the damped Mathieu equation permit to establish its full stability chart. It is then seen that dissipation broadens the regions of stability to the extent that not only the response to parametric excitations is damped, but even "negative-energy" modes are stabilized by the combined action of the parametric excitation and the damping coefficient. The extension of this analysis to the "two-step" Hill's equation shows that the stability regions become many times larger than those of the Mathieu equation. By analogy, these findings are a strong indication that the "resistive wall mode" could be stabilized by the joint action of a properly taylored time-dependent wall resistivity and a sufficient viscous dissipation in the plasma. Note that within this scheme neither the wall nor the plasma need to be in motion. An extension of this work to include more realistic models is in progress. [1] H. Tasso and G.N. Throumoulopoulos, Phys. Lett. A 271, 413 (2000).

  4. Ballooning Stability of the Compact Quasiaxially Symmetric Stellarator

    SciTech Connect

    M.H. Redi; J. Canik; R.L. Dewar; J.L. Johnson; S. Klasky; W.A. Cooper; W. Kerbichler

    2001-09-19

    The magnetohydrodynamic (MHD) ballooning stability of a compact, quasiaxially symmetric stellarator (QAS), expected to achieve good stability and particle confinement is examined with a method that can lead to estimates of global stability. Making use of fully 3D, ideal-MHD stability codes, the QAS beta is predicted to be limited above 4% by ballooning and high-n kink modes. Here MHD stability is analyzed through the calculation and examination of the ballooning mode eigenvalue isosurfaces in the 3-space [s, alpha, theta(subscript ''k'')]; s is the edge normalized toroidal flux, alpha is the field line variable, and theta(subscript ''k'') is the perpendicular wave vector or ballooning parameter. Broken symmetry, i.e., deviations from axisymmetry, in the stellarator magnetic field geometry causes localization of the ballooning mode eigenfunction, with new types of nonsymmetric, eigenvalue isosurfaces in both the stable and unstable spectrum. The isosurfaces around the most unstable points i n parameter space (well above marginal) are topologically spherical. In such cases, attempts to use ray tracing to construct global ballooning modes lead to a k-space runaway. Introduction of a reflecting cutoff in k(perpendicular) to model numerical truncation or finite Larmor radius (FLR) yields chaotic ray paths ergodically filling the allowed phase space, indicating that the global spectrum must be described using the language of quantum chaos theory. However, the isosurface for marginal stability in the cases studied are found to have a more complex topology, making estimation of FLR stabilization more difficult.

  5. Preparation of astaxanthin nanodispersions using gelatin-based stabilizer systems.

    PubMed

    Anarjan, Navideh; Nehdi, Imededdine Arbi; Sbihi, Hassen Mohamed; Al-Resayes, Saud Ibrahim; Malmiri, Hoda Jafarizadeh; Tan, Chin Ping

    2014-01-01

    The incorporation of lipophilic nutrients, such as astaxanthin (a fat soluble carotenoid) in nanodispersion systems can either increase the water solubility, stability and bioavailability or widen their applications in aqueous food and pharmaceutical formulations. In this research, gelatin and its combinations with sucrose oleate as a small molecular emulsifier, sodium caseinate (SC) as a protein and gum Arabic as a polysaccharide were used as stabilizer systems in the formation of astaxanthin nanodispersions via an emulsification-evaporation process. The results indicated that the addition of SC to gelatin in the stabilizer system could increase the chemical stability of astaxanthin nanodispersions significantly, while using a mixture of gelatin and sucrose oleate as a stabilizer led to production of nanodispersions with the smallest particle size (121.4±8.6 nm). It was also shown that a combination of gelatin and gum Arabic could produce optimal astaxanthin nanodispersions in terms of physical stability (minimum polydispersity index (PDI) and maximum zeta-potential). This study demonstrated that the mixture of surface active compounds showed higher emulsifying and stabilizing functionality compared to using them individually in the preparation of astaxanthin nanodispersions. PMID:25211006

  6. DC KIDS COUNT e-Databook Indicators

    ERIC Educational Resources Information Center

    DC Action for Children, 2012

    2012-01-01

    This report presents indicators that are included in DC Action for Children's 2012 KIDS COUNT e-databook, their definitions and sources and the rationale for their selection. The indicators for DC KIDS COUNT represent a mix of traditional KIDS COUNT indicators of child well-being, such as the number of children living in poverty, and indicators of…

  7. 34 CFR 361.84 - Performance indicators.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 2 2010-07-01 2010-07-01 false Performance indicators. 361.84 Section 361.84 Education... Standards and Performance Indicators § 361.84 Performance indicators. (a) The performance indicators establish what constitutes minimum compliance with the evaluation standards. (b) The performance...

  8. Laser controlled flame stabilization

    DOEpatents

    Early, James W. (Los Alamos, NM); Thomas, Matthew E. (Huntsville, AL)

    2001-01-01

    A method and apparatus is provided for initiating and stabilizing fuel combustion in applications such as gas turbine electrical power generating engines and jet turbine engines where it is desired to burn lean fuel/air mixtures which produce lower amounts of NO.sub.x. A laser induced spark is propagated at a distance from the fuel nozzle with the laser ignitor being remotely located from the high temperature environment of the combustion chamber. A laser initiating spark generated by focusing high peak power laser light to a sufficiently tight laser spot within the fuel to cause the ionization of air and fuel into a plasma is unobtrusive to the flow dynamics of the combustion chamber of a fuel injector, thereby facilitating whatever advantage can be taken of flow dynamics in the design of the fuel injector.

  9. Roller reamer/stabilizer

    SciTech Connect

    Hansen, M. S.

    1985-04-02

    A roller reamer/stabilizer apparatus for use on a drill string assembly. The apparatus includes a reamer body which has a number of pockets formed in the body. A cutter assembly is anchored in each pocket. The cutter assembly includes a bearing pin on which two bearing blocks are mounted with a reamer cutter mounted in between the two bearing blocks. The entire cutter assembly is first assembled and is then placed in a corresponding pocket of the reamer body. The cutter assembly is secured within the pocket by means of pull pins which are inserted transversely through the reamer body so as to engage corresponding holes which are formed in the bearing blocks of the cutter assembly. The pull pins are secured by means of snap rings that can be easily removed so that the pull pins can then be retracted to permit the cutter assembly to be replaced after it is worn.

  10. Stability of lobed balloons

    NASA Astrophysics Data System (ADS)

    Pagitz, M.; Xu, Y.; Pellegrino, S.

    This paper presents a computational study of the stability of simple lobed balloon structures. The particular structure that is investigated is a stack of pumpkin-shaped envelopes with a common axis of symmetry, and hence forming a kind of lobed cylinder. The number of the pumpkin envelopes is one of the variables that is investigated; a number of shape imperfections are also considered. This lobed cylinder is an axi-symmetric, idealised version of the lobed pumpkin balloons that have occasionally deployed into anomalous, clefted configurations. By studying in detail the behaviour of lobed cylinder we are able to draw some preliminary conclusions about general features of the behaviour of lobed pumpkin balloons.

  11. Entropy-stabilized oxides

    NASA Astrophysics Data System (ADS)

    Rost, Christina M.; Sachet, Edward; Borman, Trent; Moballegh, Ali; Dickey, Elizabeth C.; Hou, Dong; Jones, Jacob L.; Curtarolo, Stefano; Maria, Jon-Paul

    2015-09-01

    Configurational disorder can be compositionally engineered into mixed oxide by populating a single sublattice with many distinct cations. The formulations promote novel and entropy-stabilized forms of crystalline matter where metal cations are incorporated in new ways. Here, through rigorous experiments, a simple thermodynamic model, and a five-component oxide formulation, we demonstrate beyond reasonable doubt that entropy predominates the thermodynamic landscape, and drives a reversible solid-state transformation between a multiphase and single-phase state. In the latter, cation distributions are proven to be random and homogeneous. The findings validate the hypothesis that deliberate configurational disorder provides an orthogonal strategy to imagine and discover new phases of crystalline matter and untapped opportunities for property engineering.

  12. Entropy-stabilized oxides

    PubMed Central

    Rost, Christina M.; Sachet, Edward; Borman, Trent; Moballegh, Ali; Dickey, Elizabeth C.; Hou, Dong; Jones, Jacob L.; Curtarolo, Stefano; Maria, Jon-Paul

    2015-01-01

    Configurational disorder can be compositionally engineered into mixed oxide by populating a single sublattice with many distinct cations. The formulations promote novel and entropy-stabilized forms of crystalline matter where metal cations are incorporated in new ways. Here, through rigorous experiments, a simple thermodynamic model, and a five-component oxide formulation, we demonstrate beyond reasonable doubt that entropy predominates the thermodynamic landscape, and drives a reversible solid-state transformation between a multiphase and single-phase state. In the latter, cation distributions are proven to be random and homogeneous. The findings validate the hypothesis that deliberate configurational disorder provides an orthogonal strategy to imagine and discover new phases of crystalline matter and untapped opportunities for property engineering. PMID:26415623

  13. IMPROVED ROOF STABILIZATION TECHNOLOGIES

    SciTech Connect

    M.A. Ebadian, Ph.D.

    1999-01-01

    Many U.S. Department of Energy (DOE) remediation sites have performed roof repair and roof replacement to stabilize facilities prior to performing deactivation and decommissioning (D&D) activities. This project will review the decision criteria used by these DOE sites, along with the type of repair system used for each different roof type. Based on this information, along with that compiled from roofing experts, a decision-making tool will be generated to aid in selecting the proper roof repair systems. Where appropriate, innovative technologies will be reviewed and applied to the decision-making tool to determine their applicability. Based on the results, applied research and development will be conducted to develop a method to repair these existing roofing systems, while providing protection for the D and D worker in a cost-efficient manner.

  14. Aldehyde-stabilized cryopreservation.

    PubMed

    McIntyre, Robert L; Fahy, Gregory M

    2015-12-01

    We describe here a new cryobiological and neurobiological technique, aldehyde-stabilized cryopreservation (ASC), which demonstrates the relevance and utility of advanced cryopreservation science for the neurobiological research community. ASC is a new brain-banking technique designed to facilitate neuroanatomic research such as connectomics research, and has the unique ability to combine stable long term ice-free sample storage with excellent anatomical resolution. To demonstrate the feasibility of ASC, we perfuse-fixed rabbit and pig brains with a glutaraldehyde-based fixative, then slowly perfused increasing concentrations of ethylene glycol over several hours in a manner similar to techniques used for whole organ cryopreservation. Once 65% w/v ethylene glycol was reached, we vitrified brains at -135 °C for indefinite long-term storage. Vitrified brains were rewarmed and the cryoprotectant removed either by perfusion or gradual diffusion from brain slices. We evaluated ASC-processed brains by electron microscopy of multiple regions across the whole brain and by Focused Ion Beam Milling and Scanning Electron Microscopy (FIB-SEM) imaging of selected brain volumes. Preservation was uniformly excellent: processes were easily traceable and synapses were crisp in both species. Aldehyde-stabilized cryopreservation has many advantages over other brain-banking techniques: chemicals are delivered via perfusion, which enables easy scaling to brains of any size; vitrification ensures that the ultrastructure of the brain will not degrade even over very long storage times; and the cryoprotectant can be removed, yielding a perfusable aldehyde-preserved brain which is suitable for a wide variety of brain assays. PMID:26408851

  15. The stability of liquid dispersions in low gravity

    NASA Technical Reports Server (NTRS)

    Lacy, L. L.; Otto, G. H.

    1974-01-01

    The stability of three different dispersions of oil and water prepared on Skylab 4 is compared with the same dispersions made on earth. The stability of the emulsions has been studied by two independent optical techniques. An analysis of the data indicates that all the investigated emulsions were stable over a period of 10 hr, whereas the fluids separated completely on earth in 10 sec. This experiment indicates that the rate of coalescence in low gravity is at least 3 millionths times that on earth. A knowledge of the coalescence rate in low gravity is important in the solidification of immiscible alloys in space. The parameters obtained for this experiment are compared with those of liquid metals to determine if the same stability could be achieved with immiscible alloys.

  16. Effects of increased anterior-posterior voluntary sway frequency on mechanical and perceived postural stability.

    PubMed

    Martin Lorenzo, Teresa; Vanrenterghem, Jos

    2015-02-01

    Despite a substantial number of studies, the interaction between mechanical indicators of stability and perception of instability remains unclear. The purpose of this study was to determine the effect of sway frequency and verbal restraint on mechanical and perceived postural stability. Fourteen participants underwent a series of standing voluntary anterior-posterior swaying trials at three frequencies (20, 40, and 60bpm) and two levels of restraint (non restraint and verbally restraint to swaying at the ankle). Repeated measures ANOVA tests revealed greater mechanical stability defined though the margin of stability, and greater horizontal ground reaction forces, while the center of pressure excursions remained unchanged with increasing frequency. Furthermore, ground reaction forces were greater in the non-restraint condition. Moreover, a tendency toward greater perceived instability with increasing voluntary sway frequency was observed. Our results indicate that variations in sway frequency and verbal restraint resulted in noticeable alterations in mechanical indicators of stability, with no clear effect on perceived instability. PMID:25498287

  17. Comparative stability of repackaged metoprolol tartrate tablets.

    PubMed

    Yang, Yongsheng; Gupta, Abhay; Carlin, Alan S; Faustino, Patrick J; Lyon, Robbe C; Ellison, Christopher D; Rothman, Barry; Khan, Mansoor A

    2010-01-29

    The stability of metoprolol tartrate tablets packaged in original high density polyethylene containers and repackaged in USP Class A unit-dose blister packs was investigated. Studies were conducted at 25 degrees C/60% relative humidity (RH) for 52 weeks and at 40 degrees C/75% RH for 13 weeks. The potency, dissolution, water content, loss on drying and hardness of the drug products were analyzed. Results indicated no differences in the stability between the tablets in both packages stored under 25 degrees C/60% RH. No difference in potency was found in both packages under either condition. However, a significant weight increase due to moisture uptake was observed for the repackaged tablets stored under 40 degrees C/75% RH. The weight increase was accompanied by a decrease in tablet hardness (6.5-0 kp) and a increase in dissolution rate (51-92%) in 5 min. Near-infrared (NIR) chemical imaging also monitored moisture uptake of the tablet non-invasively through the package. The observed changes in product stability may adversely affect the products bioavailability profile, even though the potency of the active drug remained within USP specification range of 90-110%. Study results suggest product quality can be negatively impacted even when using USP Class A repackaging materials. PMID:19879937

  18. Optimization of photocatalytic degradation of meloxicam using titanium dioxide nanoparticles: application to pharmaceutical wastewater analysis, treatment, and cleaning validation.

    PubMed

    Nadim, Ahmed H; Al-Ghobashy, Medhat A; Nebsen, Marianne; Shehata, Mostafa A

    2015-10-01

    Meloxicam is a commonly prescribed nonsteroidal anti-inflammatory drug with analgesic and fever-reducing effects. In this study, photocatalytic degradation of meloxicam in the presence of TiO2 nanoparticles (TiO2NP) was optimized and applied for pharmaceutical wastewater treatment. A validated stability-indicating orthogonal testing protocol (reversed-phase (RP)-HPLC and capillary zone electrophoresis) was developed and validated for monitoring of meloxicam concentration in the presence of its photodegradation products. Fractional factorial design was employed in order to investigate the effects of pH, irradiation time, UV light intensity, TiO2NP loading, and initial meloxicam concentration on the efficiency of the process. The light intensity was found as the most significant parameter followed by irradiation time and concentration, respectively. The most influencing interactions were noted between irradiation time-concentration and irradiation time-light intensity. The kinetics of meloxicam degradation was investigated at the optimum set of experimental conditions. The protocol was successfully applied for treatment of incurred water samples collected during various cleaning validation cycles. A percentage degradation of 77.34?±?0.02 % was achieved upon irradiation of samples containing 64.57?±?0.09 ?g/mL with UV light (1012 ?W/cm(2), 8 h) in the presence of 0.4 mg/mL TiO2NP at pH 9.0?±?0.05. Treatment of wastewaters collected during the cleaning validation of each product separately rather than the combined waste should result in a significant improvement in the economics of pharmaceutical wastewater treatment. This could be attributed to the relatively small waste volumes and the ability to tailor the experimental conditions to achieve maximum efficiency. PMID:26006070

  19. [Indications for photodynamic therapy in age-related macular degeneration].

    PubMed

    Soubrane, G; Kuhn, D; Coscas, G

    2004-01-01

    Exudative age-related macular degeneration (ARMD) is now benefitting from new therapeutic approaches. Three international randomized clinical trials have demonstrated the efficacy of photodynamic therapy (PDT) in stabilizing visual acuity at 2 years. PDT is based on the activation of a photosensitizer with an adapted wavelength. In age-related macular degeneration, the photosensitizer used is verteporfin (Visudyne), which accumulates preferentially in choroidal new vessels. Functional results are obtained on the basis of a strict classification based on fluorescein angiography examining the type of the new vessels responsible for exudative ARMD. Thus, subfoveal lesions, either predominantly classic (>50%) or occult only, are the indication for PDT. Classic CNVs where laser photocoagulation thermal burns extend into the foveola may be an extrapolation of the indication for PDT. In addition, fluorescein angiography is essential for considering retreatment, usually necessary. Demonstrated growth and the persistence of leakage from the CNV is an absolute indication for a new session of PDT. A number of features still require assessment in order to define the responder group more accurately and to refine and possibly simplify the indications for retreatment. PMID:14968084

  20. Stability of Behavioral Ratings of Children with SLI.

    ERIC Educational Resources Information Center

    Redmond, Sean M.; Rice, Mabel L.

    2002-01-01

    A study investigated the long-term stability of the teacher and parent behavioral ratings of 37 children with specific language impairment. Results indicate diminishment in teacher-reported behavior problems in most areas of socioemotional development from kindergarten to second grade and increasing congruence between teacher and parent ratings.…