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Sample records for broth dilution method

  1. Antimicrobial susceptibility testing of Australian isolates of Brachyspira hyodysenteriae using a new broth dilution method.

    PubMed

    Karlsson, Märit; Oxberry, Sophy L; Hampson, David J

    2002-01-01

    The antimicrobial susceptibilities of 76 field isolates of Brachyspira hyodysenteriae from different states of Australia were tested in a newly developed broth dilution procedure. The antimicrobial agents used were tiamulin, valnemulin, tylosin, erythromycin, lincomycin and clindamycin. The results from the broth dilution susceptibility testing of 39 of the isolates were compared with results obtained for the same isolates using the agar dilution method. Amongst the isolates tested by broth dilution, 17 were from three farms and had been collected over a number of years. Their pulsed field gel electrophoresis pattern previously had been determined. The broth dilution technique was simple to use, less labor intensive than agar dilution, and gave clear end points. The results obtained using the two methods generally corresponded well, although in a few cases the MIC obtained by broth dilution were lower than those with agar dilution. For the 76 isolates tested by broth dilution, the MIC(90) (mg/l) was: tiamulin, 1; valnemulin, 0.5; tylosin>256; erythromycin>256; lincomycin, 64 and clindamycin, 16. Only minor differences in susceptibility patterns were found amongst isolates from different Australian states. Over all the isolates, and also amongst the isolates obtained from different years on the three farms, there was no trend for the susceptibility of the isolates to alter with time. PMID:11731165

  2. Evaluation of agar dilution and broth microdilution methods to determine the disinfectant susceptibility.

    PubMed

    Wu, Guoyan; Yang, Qianru; Long, Mei; Guo, Lijuan; Li, Bei; Meng, Yue; Zhang, Anyun; Wang, Hongning; Liu, Shuliang; Zou, Likou

    2015-11-01

    A variety of disinfectants have been widely used in veterinary hygiene, food industries and environments, which could induce the development of bacterial resistance to disinfectants. The methods used to investigate antimicrobial effects of disinfectant vary considerably among studies, making comparisons difficult. In this study, agar dilution and broth microdilution methods were used to compare the antimicrobial activities of four quaternary ammonium compounds (QACs) against foodborne and zoonotic pathogens. The potential relationship between the presence of QACs resistance genes and phenotypic resistance to QACs was also investigated. Our results indicated that the minimum inhibitory concentrations (MICs) determined by two methods might be different depended upon different QACs and bacteria applied. Regardless of the testing methods, Klebsiella pneumoniae was more tolerant among Gram-negative strains to four QACs, followed by Salmonella and Escherichia coli. The agreement between MICs obtained by the two methods was good, for benzalkonium chloride (78.15%), didecyldimethylammonium chloride (DDAC) (82.35%), cetylpyridinium chloride (CTPC) (97.48%) and cetyltrimethylammonium bromide (CTAB) (99.16%), respectively. Among all Gram-negative bacteria, 94.55% (n=52) of qacEΔ1-positive strains showed higher MICs (512 mg l(-1)) to CTAB. The qacEΔ1 gene was highly associated (P<0.05) with the high MICs of QACs (⩾512 mg l(-1)). In addition, DDAC remained as the most effective disinfectant against both Gram-positive and Gram-negative bacteria. This is the first study that compared the agar dilution and broth microdilution methods to assess the antimicrobial activity of QACs. The study demonstrated the need to standardize method that would be used in evaluating QACs antimicrobial properties in the future. PMID:25944532

  3. Comparison of agar dilution and antibiotic gradient strip test with broth microdilution for susceptibility testing of swine Brachyspira species.

    PubMed

    Mirajkar, Nandita S; Gebhart, Connie J

    2016-03-01

    Production-limiting diseases in swine caused by Brachyspira are characterized by mucohemorrhagic diarrhea (B. hyodysenteriae and "B. hampsonii") or mild colitis (B. pilosicoli), while B. murdochii is often isolated from healthy pigs. Emergence of novel pathogenic Brachyspira species and strains with reduced susceptibility to commonly used antimicrobials has reinforced the need for standardized susceptibility testing. Two methods are currently used for Brachyspira susceptibility testing: agar dilution (AD) and broth microdilution (BMD). However, these tests have primarily been used for B. hyodysenteriae and rarely for B. pilosicoli. Information on the use of commercial susceptibility testing products such as antibiotic gradient strips is lacking. Our main objective was to validate and compare the susceptibility results, measured as the minimum inhibitory concentration (MIC), of 6 antimicrobials for 4 Brachyspira species (B. hyodysenteriae, "B. hampsonii", B. pilosicoli, and B. murdochii) by BMD and AD (tiamulin, valnemulin, lincomycin, tylosin, and carbadox) or antibiotic gradient strip (doxycycline) methods. In general, the results of a high percentage of all 4 Brachyspira species differed by ±1 log2 dilution or less by BMD and AD for tiamulin, valnemulin, lincomycin, and tylosin, and by BMD and antibiotic gradient strip for doxycycline. The carbadox MICs obtained by BMD were 1-5 doubling dilutions different than those obtained by AD. BMD for Brachyspira was quicker to perform with less ambiguous interpretation of results when compared with AD and antibiotic gradient strip methods, and the results confirm the utility of BMD in routine diagnostics. PMID:26965233

  4. An improved method for the recovery of Salmonella serovars from orange juice using universal preenrichment broth.

    PubMed

    Hammack, T S; Amaguaña, R M; Andrews, W H

    2001-05-01

    The relative effectiveness of three methods for the recovery of Salmonella serovars from orange juice was determined. One method, a modified Bacteriological Analytical Manual (BAM) procedure consisted of preenrichment in lactose broth at 35 degrees C for 24 h, selective enrichment, and selective plating. Another method, a National Centers for Disease Control and Prevention (CDC 1) procedure, consisted of direct enrichment in tetrathionate broth at 35 degrees C for 24 and 48 h, followed by selective plating. The third method (also from CDC and designated CDC 2) consisted of preenrichment in Universal Preenrichment (UP) broth at 35 degrees C for 24 h, selective enrichment, and selective plating. In 10 experiments encompassing five different Salmonella serovars and 200 test portions per broth, the CDC 1 method recovered 141 Salmonella-positive test portions, the BAM method recovered 151, and the CDC 2 method recovered 171. In 2 of the 10 experiments, with two different Salmonella serovars, the BAM recovered significantly fewer (P < 0.05) Salmonella-positive test portions than did the CDC 2 method. On the basis of the above results, the second phase of this study focused on a comparison of the effectiveness of the BAM-recommended lactose broth and the CDC 2-recommended UP broth as preenrichment media for the recovery of Salmonella serovars from pasteurized and unpasteurized orange juice. Subsequent culture treatment of the two preenrichments was identical so that the effect of other variables (e.g., different selective enrichment media, various incubation temperatures, and different selective plating agars) on the relative performance of these two preenrichment media was excluded. In one of nine experiments, with pasteurized orange juice, lactose broth recovered significantly fewer (P < 0.05) Salmonella-positive test portions than did UP broth. For the combined results of the nine pasteurized orange juice experiments (180 test portions per broth), lactose broth

  5. Comparative Analysis of Disc Diffusion and E-test with Broth Micro-dilution for Susceptibility Testing of Clinical Candida Isolates Against Amphotericin B, Fluconazole, Voriconazole and Caspofungin

    PubMed Central

    Bhattacharyya, Sayan; Gupta, Prashant; Banerjee, Gopa; Singh, Mastan

    2015-01-01

    Background Antifungal susceptibility testing remains an area of intense interest because of the increasing number of clinical isolates resistant to antifungal therapy. Clinical and Laboratory Standards Institute has proposed reference broth micro dilution (BMD) method for susceptibility testing. The reference method is time-consuming and poorly suited for the routine clinical laboratory setting. Agar-based susceptibility testing methods, disk diffusion (DD) method and the E-test method can be an easier, reliable and less time consuming alternative for the BMD method. Aim To compare the results of Amphotericin B, fluconazole, voriconazole, and Caspofungin susceptibility testing by DD, and the E-test method with the CLSI reference method for clinical Candida isolates. Materials and Methods Broth Microdilution (BMD), E-test and Disk diffusion testing of the various clinical Candida isolates was performed in accordance with CLSI documents. The results obtained were analysed and compared. Results The categorical agreement for Amphotericin B, fluconazole, voriconazole, and Caspofungin susceptibility results by E-test and DD method was 65.2%, 67.4%; 100%, 82.6%; 100%, 100%; 100%, 97.8% respectively. Conclusion The agar-based E-test and disk diffusion methods are reliable alternatives to the BMD method for Candida isolates when test susceptible to fluconazole, voriconazole, and Caspofungin, however the susceptibility testing results must be interpreted with caution in case of Amphotericin B. PMID:26675415

  6. A Reference Broth Microdilution Method for Dalbavancin In Vitro Susceptibility Testing of Bacteria that Grow Aerobically.

    PubMed

    Koeth, Laura M; DiFranco-Fisher, Jeanna M; McCurdy, Sandra

    2015-01-01

    Antimicrobial susceptibility testing (AST) is performed to assess the in vitro activity of antimicrobial agents against various bacteria. The AST results, which are expressed as minimum inhibitory concentrations (MICs) are used in research for antimicrobial development and monitoring of resistance development and in the clinical setting for antimicrobial therapy guidance. Dalbavancin is a semi-synthetic lipoglycopeptide antimicrobial agent that was approved in May 2014 by the Food and Drug Administration (FDA) for the treatment of acute bacterial skin and skin structure infections caused by Gram-positive organisms. The advantage of dalbavancin over current anti-staphylococcal therapies is its long half-life, which allows for once-weekly dosing. Dalbavancin has activity against Staphylococcus aureus (including both methicillin-susceptible S. aureus [MSSA] and methicillin-resistant S. aureus [MRSA]), coagulase-negative staphylococci, Streptococcus pneumoniae, Streptococcus anginosus group, β-hemolytic streptococci and vancomycin susceptible enterococci. Similar to other recent lipoglycopeptide agents, optimization of CLSI and ISO broth susceptibility test methods includes the use of dimethyl sulfoxide (DMSO) as a solvent when preparing stock solutions and polysorbate 80 (P80) to alleviate adherence of the agent to plastic. Prior to the clinical studies and during the initial development of dalbavancin, susceptibility studies were not performed with the use of P-80 and MIC results tended to be 2-4 fold higher and similarly higher MIC results were obtained with the agar dilution susceptibility method. Dalbavancin was first included in CLSI broth microdilution methodology tables in 2005 and amended in 2006 to clarify use of DMSO and P-80. The broth microdilution (BMD) procedure shown here is specific to dalbavancin and is in accordance with the CLSI and ISO methods, with step-by-step detail and focus on the critical steps added for clarity. PMID:26381422

  7. Development of Similar Broth Microdilution Methods to Determine the Antimicrobial Susceptibility of Flavobacterium columnare and F. psychrophilum.

    PubMed

    Gieseker, Charles M; Crosby, Tina C; Mayer, Tamara D; Bodeis, Sonya M; Stine, Cynthia B

    2016-03-01

    Flavobacterium columnare and F. psychrophilum are major fish pathogens that cause diseases that may require antimicrobial therapy. Choice of appropriate treatment is dependent upon determining the antimicrobial susceptibility of isolates. Therefore we optimized methods for broth microdilution testing of F. columnare and F. psychrophilum to facilitate standardizing an antimicrobial susceptibility test. We developed adaptations to make reproducible broth inoculums and confirmed the proper incubation time and media composition. We tested the stability of potential quality-control bacteria and compared test results between different operators. Log phase occurred at 48 h for F. columnare and 72-96 h for F. psychrophilum, confirming the test should be incubated at 28°C for approximately 48 h and at 18°C for approximately 96 h, respectively. The most consistent susceptibility results were achieved with plain, 4-g/L, dilute Mueller-Hinton broth supplemented with dilute calcium and magnesium. Supplementing the broth with horse serum did not improve growth. The quality-control strains, Escherichia coli ATCC 25922 and Aeromonas salmonicida subsp. salmonicida ATCC 33658, yielded stable minimal inhibitory concentrations (MIC) against all seven antimicrobials tested after 30 passes at 28°C and 15 passes at 18°C. In comparison tests, most MICs of the isolates agreed 100% within one drug dilution for ampicillin, florfenicol, and oxytetracycline. The agreement was lower with the ormetoprim-sulfdimethoxine combination, but there was at least 75% agreement for all but one isolate. These experiments have provided methods to help standardize antimicrobial susceptibility testing of these nutritionally fastidious aquatic bacteria. Received June 24, 2015; accepted October 2, 2015. PMID:26949840

  8. Comparative performance of isolation methods using Preston broth, Bolton broth and their modifications for the detection of Campylobacter spp. from naturally contaminated fresh and frozen raw poultry meat.

    PubMed

    Seliwiorstow, T; De Zutter, L; Houf, K; Botteldoorn, N; Baré, J; Van Damme, I

    2016-10-01

    The performance of different isolation methods was evaluated for the detection of Campylobacter from naturally contaminated raw poultry meat. Therefore, fresh and frozen poultry meat samples were analysed using the standard procedure (ISO 10272-1:2006), enrichment in Preston broth, and enrichment in modified Bolton broth (supplemented with (i) potassium clavulanate (C-BB), (ii) triclosan (T-BB), (iii) polymyxin B (P-BB)). The enrichment cultures were streaked onto both modified charcoal cefoperazone deoxycholate agar (mCCDA) and RAPID'Campylobacter agar (RCA). Moreover, direct plating on mCCDA and RCA was performed to quantify Campylobacter. In total, 33 out of 59 fresh retail meat samples (55.9%) were Campylobacter positive. For both fresh and frozen poultry meat samples, enrichment in Bolton broth (ISO 10272-1:2006) resulted in a higher number of positive samples than enrichment in Preston broth. Supplementation of Bolton broth with potassium clavulanate (C-BB) and triclosan (T-BB) enhanced the Campylobacter recovery from fresh poultry meat compared to non-supplemented Bolton broth, although the use of C-BB was less applicable than T-BB for Campylobacter recovery from frozen samples. Additionally, the use of RCA resulted in a higher isolation rate compared to mCCDA. The present study demonstrates the impact of culture medium on the recovery of Campylobacter from fresh and frozen naturally contaminated poultry meat samples and can support laboratories in choosing the most appropriate culturing method to detect Campylobacter. PMID:27391222

  9. Recommendation for a Standardised Method of Broth Microdilution Susceptibility Testing for Porcine Bordetella bronchiseptica

    PubMed Central

    Prüller, Sandra; Frömke, Cornelia; Kaspar, Heike; Klein, Günter; Kreienbrock, Lothar; Kehrenberg, Corinna

    2015-01-01

    The objective was to establish and standardise a broth microdilution susceptibility testing method for porcine Bordetella (B.) bronchiseptica. B. bronchiseptica isolates from different geographical regions and farms were genotyped by macrorestriction analysis and subsequent pulsed-field gel electrophoresis. One reference and one type strain plus two field isolates of B. bronchiseptica were chosen to analyse growth curves in four different media: cation-adjusted Mueller-Hinton broth (CAMHB) with and without 2% lysed horse blood, Brain-Heart-Infusion (BHI), and Caso broth. The growth rate of each test strain in each medium was determined by culture enumeration and the suitability of CAMHB was confirmed by comparative statistical analysis. Thereafter, reference and type strain and eight epidemiologically unrelated field isolates of B. bronchiseptica were used to test the suitability of a broth microdilution susceptibility testing method following CLSI-approved performance standards given in document VET01-A4. Susceptibility tests, using 20 antimicrobial agents, were performed in five replicates, and data were collected after 20 and 24 hours incubation and statistically analysed. Due to the low growth rate of B. bronchiseptica, an incubation time of 24 hours resulted in significantly more homogeneous minimum inhibitory concentrations after five replications compared to a 20-hour incubation. An interlaboratory comparison trial including susceptibility testing of 24 antimicrobial agents revealed a high mean level of reproducibility (97.9%) of the modified method. Hence, in a harmonization for broth microdilution susceptibility testing of B. bronchiseptica, an incubation time of 24 hours in CAMHB medium with an incubation temperature of 35°C and an inoculum concentration of approximately 5 x 105 cfu/ml was proposed. PMID:25910232

  10. Estimation method for serial dilution experiments.

    PubMed

    Ben-David, Avishai; Davidson, Charles E

    2014-12-01

    Titration of microorganisms in infectious or environmental samples is a corner stone of quantitative microbiology. A simple method is presented to estimate the microbial counts obtained with the serial dilution technique for microorganisms that can grow on bacteriological media and develop into a colony. The number (concentration) of viable microbial organisms is estimated from a single dilution plate (assay) without a need for replicate plates. Our method selects the best agar plate with which to estimate the microbial counts, and takes into account the colony size and plate area that both contribute to the likelihood of miscounting the number of colonies on a plate. The estimate of the optimal count given by our method can be used to narrow the search for the best (optimal) dilution plate and saves time. The required inputs are the plate size, the microbial colony size, and the serial dilution factors. The proposed approach shows relative accuracy well within ±0.1log10 from data produced by computer simulations. The method maintains this accuracy even in the presence of dilution errors of up to 10% (for both the aliquot and diluent volumes), microbial counts between 10(4) and 10(12) colony-forming units, dilution ratios from 2 to 100, and plate size to colony size ratios between 6.25 to 200. PMID:25205541

  11. Analysis of pH and buffer effects on flucytosine activity in broth dilution susceptibility testing of Candida albicans in two synthetic media.

    PubMed Central

    Calhoun, D L; Galgiani, J N

    1984-01-01

    We examined the influences of different pH levels and three different buffers on flucytosine activity against 12 isolates of Candida albicans in two synthetic media, yeast nitrogen base (YNB) and synthetic amino acid medium-fungal (SAAMF), using broth dilution techniques and measuring the endpoints of visual MICs and turbidimetric 50% inhibitory concentrations. The two media were originally prepared as follows: YNB, unbuffered, pH 5.6; SAAMF, buffered with morpholinepropanesulfonic acid-Tris, pH 7.4; the resultant geometric mean MIC and 50% inhibitory concentration of 5-FC were 78- and 32-fold higher, respectively, in SAAMF. Raising the pH of YNB or lowering the pH of SAAMF had virtually no effect on these differences in MIC and 50% inhibitory concentration in the two media. In contrast, virtually all of the discrepancy appeared to be due to morpholinepropanesulfonic acid-Tris, which exerted concentration-dependent inhibition of flucytosine activity not evident when N-2-hydroxyethylpiperazine-N'-ethanesulfonic acid or phosphate buffer systems were substituted. In other turbidimetric studies, growth was slowed more than 50% in YNB as the pH was raised to 7.4, regardless of which buffer was used. Based on our studies, we recommend modifying the composition of SAAMF by substituting a nonantagonistic buffer if any buffer is to be used with SAAMF in the testing of flucytosine. With this modification, SAAMF warrants further study as a generally applicable medium for fungal-susceptibility testing. PMID:6391370

  12. Evaluation of diffusion and dilution methods to determine the antibacterial activity of plant extracts.

    PubMed

    Klancnik, Anja; Piskernik, Sasa; Jersek, Barbara; Mozina, Sonja Smole

    2010-05-01

    The aim of this study was to evaluate diffusion and dilution methods for determining the antibacterial activity of plant extracts and their mixtures. Several methods for measurement of the minimal inhibitory concentration (MIC) of a plant extract are available, but there is no standard procedure as there is for antibiotics. We tested different plant extracts, their mixtures and phenolic acids on selected gram-positive (Staphylococcus aureus, Bacillus cereus, and Listeria monocytogenes) and gram-negative bacteria (Escherichia coli O157:H7, Salmonella Infantis, Campylobacter jejuni, Campylobacter coli) with the disk diffusion, agar dilution, broth microdilution and macrodilution methods. The disk diffusion method was appropriate only as a preliminary screening test prior to quantitative MIC determination with dilution methods. A comparison of the results for MIC obtained by agar dilution and broth microdilution was possible only for gram-positive bacteria, and indicated the latter as the most accurate way of assessing the antimicrobial effect. The microdilution method with TTC (2,3,5-triphenyl tetrazolium chloride) or INT (2-p-iodophenyl-3-p-nitrophenyl-5-phenyl tetrazolium chloride) to indicate the viability of aerobic bacteria was found to be the best alternative approach, while only ATP determination was appropriate for microaerophilic Campylobacter spp. Using survival curves the kinetics of bacterial inactivation on plant extract exposure was followed for 24h and in this way the MIC values determined by the microdilution method were confirmed as the concentrations of extracts that inhibited bacterial growth. We suggest evaluation of the antibacterial activity of plant extracts using the broth microdilution method as a fast screening method for MIC determination and the macrodilution method at selected MIC values to confirm bacterial inactivation. Campylobacter spp. showed a similar sensitivity to plant extracts as the tested gram-positive bacteria, but S

  13. CLSI broth microdilution method for testing susceptibility of Malassezia pachydermatis to thiabendazole

    PubMed Central

    Nascente, Patrícia da Silva; Meinerz, Ana Raquel Mano; de Faria, Renata Osório; Schuch, Luiz Filipe Damé; Meireles, Mário Carlos Araújo; de Mello, João Roberto Braga

    2009-01-01

    Thiabendazole, classified as antiparasitic and also used as an antifungal drug, can be found as otological solution indicated for treatment of parasitic and fungal external otitis in small animals. Malassezia pachydermatis is a yeast recognized as a normal inhabitant on the skin and mucous membranes of dogs and cats. However, it is considered an opportunistic agent that causes external otitis and dermatitis in these animals. The aim of this study was to evaluate the in vitro effect of thiabendazole against 51 isolates of M. pachydermatis using the CLSI Broth Microdilution method that has been adapted for this yeast species (NCCLS, 2002). Based on this test, the Minimum Inhibitory Concentrations (MIC) of thiabendazol was calculated. Subsequently, the susceptibility of each isolate against this antifungal was determined. It was observed that the MIC of thiabendazole against M. pachydermatis ranged from 0.03 to > 4 µg/mL. A total of 13.7% of the isolates were found to be resistant, 47.1% were intermediate and 39.2% were sensitive to the drug. The rate of resistance of the yeasts against thiabendazole was similar to the results previously obtained with other antifungals, while the adapted broth microdilution technique used in this study proved to be efficient. PMID:24031347

  14. In Vitro Antibiotic Susceptibilities of Yersinia pestis Determined by Broth Microdilution following CLSI Methods

    PubMed Central

    Hershfield, Jeremy; Marchand, Charles; Miller, Lynda; Halasohoris, Stephanie; Purcell, Bret K.; Worsham, Patricia L.

    2015-01-01

    In vitro susceptibilities to 45 antibiotics were determined for 30 genetically and geographically diverse strains of Yersinia pestis by the broth microdilution method at two temperatures, 28°C and 35°C, following Clinical and Laboratory Standards Institute (CLSI) methods. The Y. pestis strains demonstrated susceptibility to aminoglycosides, quinolones, tetracyclines, β-lactams, cephalosporins, and carbapenems. Only a 1-well shift was observed for the majority of antibiotics between the two temperatures. Establishing and comparing antibiotic susceptibilities of a diverse but specific set of Y. pestis strains by standardized methods and establishing population ranges and MIC50 and MIC90 values provide reference information for assessing new antibiotic agents and also provide a baseline for use in monitoring any future emergence of resistance. PMID:25583720

  15. Separation technologies for the recovery and dehydration of alcohols from fermentation broths

    EPA Science Inventory

    Multi-column distillation followed by molecular sieve adsorption is currently the standard method for producing fuel grade ethanol from dilute fermentation broths in modern corn-to-ethnol facilities. As the liquid biofuels industry transitions to lignocellulosic feedstocks, expan...

  16. Development of an Liquid Chromatography-Tandem Mass Spectrometry Method for the Determination of Amoxicillin in Broth Medium and its Application to an In Vitro Pharmacokinetic and Pharmacodynamic Model.

    PubMed

    Zhang, Shujing; Yang, Fan; Guo, Beining; Chen, Yuancheng; Wu, Xiaojie; Liang, Wang; Shi, Yaoguo; Zhang, Jing

    2016-02-01

    A simple, rapid and highly sensitive liquid chromatographic-tandem mass spectrometry (LC-MS-MS) method has been developed and validated for the quantification of amoxicillin in broth-a liquid bacterial culture medium. After appropriate dilution with ultrapure water, broth samples containing amoxicillin and an internal standard (IS) were extracted by acetonitrile and dichloromethane. The extract was injected into the system. The analyte and the IS were separated by a prepacked Atlantis C18 column using acetonitrile-0.1% formic acid as a mobile phase and detected by selected reaction monitoring in electrospray ionization positive ion mode. The calibration curve of amoxicillin was linear over the concentration range of 0.05-20.00 µg/mL. The mean recovery of amoxicillin from broth was 71.7%, and the intra- and interday precision and accuracies of the assay were within 10%. Amoxicillin was stable in broth for 12 h at room temperature (24°C), for 6.5 months at -80°C and for 24 h after preparation in an autosampler at room temperature. It has been successfully applied to an in vitro pharmacokinetic (PK) and pharmacodynamic (PD) model in which the broth is used for bacterial growth. The method provides high-throughput biological analysis to facilitate the in vitro PK and PD model of amoxicillin. PMID:26386906

  17. Modified agar dilution susceptibility testing method for determining in vitro activities of antifungal agents, including azole compounds.

    PubMed Central

    Yoshida, T; Jono, K; Okonogi, K

    1997-01-01

    In vitro activities of antifungal agents, including azole compounds, against yeasts were easily determined by using RPMI-1640 agar medium and by incubating the plates in the presence of 20% CO2. The end point of inhibition was clear by this method, even in the case of azole compounds, because of the almost complete inhibition of yeast growth at high concentrations which permitted weak growth of some Candida strains by traditional methods. MICs obtained by the agar dilution method were similar to those obtained by the broth dilution method proposed by the National Committee for Clinical Laboratory Standards. PMID:9174197

  18. Comparison of Etest with Modified Broth Microdilution Method for Testing Susceptibility of Aspergillus spp. to Voriconazole

    PubMed Central

    Serrano, M. C.; Morilla, D.; Valverde, A.; Chávez, M.; Espinel-Ingroff, A.; Claro, R.; Ramírez, M.; Mazuelos, E. Martín

    2003-01-01

    We compared the Etest with a broth microdilution method, performed according to a modified National Committee for Clinical Laboratory Standards guideline (M38-A), for determining the in vitro susceptibility of 77 isolates of Aspergillus spp. (26 A. fumigatus, 21 A. flavus, 10 A. terreus, 9 A. niger, 5 A. nidulellus, 4 A. glaucus, and 2 A. flavipes isolates). Overall, there was 92.2% agreement between both methods when Etest MICs were read at 24 h and 83.1% agreement when both methods were read at 48 h. When Etest MICs were read at 24 h, the agreement was >90% for all species tested except for A. fumigatus (84.6%). When Etest MICs were read at 48 h, the agreement ranged from 50 to 100%. The poorest agreement was seen with A. glaucus (50%) and A. fumigatus (65%). Where a discrepancy was observed between Etest and the reference method, the Etest MIC was generally higher. The Etest appears to be a suitable alternative procedure for testing the susceptibility of Aspergillus spp. to voriconazole. PMID:14605181

  19. An improved HPLC-DAD method for clavulanic acid quantification in fermentation broths of Streptomyces clavuligerus.

    PubMed

    Ramirez-Malule, Howard; Junne, Stefan; López, Carlos; Zapata, Julian; Sáez, Alex; Neubauer, Peter; Rios-Estepa, Rigoberto

    2016-02-20

    Clavulanic acid (CA) is an important secondary metabolite commercially produced by cultivation of Streptomyces clavuligerus (Sc). It is a potent inhibitor of bacterial β-lactamases. In this work, a specific and improved high performance liquid chromatography (HPLC) method, using a C-18 reversed phase column, diode array detector and gradient elution for CA quantification in fermentation broths of Sc, was developed and successfully validated. Samples were imidazole-derivatized for the purpose of creating a stable chromophore (clavulanate-imidazole). The calibration curve was linear over a typical range of CA concentration between 0.2 and 400mg/L. The detection and quantification limits were 0.01 and 0.02mg/L, respectively. The precision of the method was evaluated for CA spiked into production media and a recovery of 103.8%, on average, was obtained. The clavulanate-imidazole complex was not stable when the samples were not cooled during the analysis. The recovery rate was 39.3% on average. This assay was successfully tested for CA quantification in samples from Sc fermentation, using both, a chemically defined and a complex medium. PMID:26760242

  20. Validation of a HILIC Method for the Analysis of Ergothioneine in Fermentation Broth.

    PubMed

    Liu, Qi; Zhang, Weiya; Wang, Hongyu; Li, Yunhua; Liu, Wei; Wang, Qunjie; Liu, Dongze; Chen, Ning; Jiang, Wenxia

    2016-07-01

    A hydrophilic interaction liquid chromatography method has been established for the quantification of ergothioneine (EGT) in fermentation broth. Chromatographic separation was conducted on a Venusil hydrophilic interaction liquid chromatography (HILIC) column (250 × 4.6 mm, 5 µm) at an elution rate of 1.0 mL/min with an isocratic mobile phase consisting of acetonitrile/20 mmol/L ammonium acetate solution (85 : 15, v/v) adjusted to pH 6.0 with acetic acid. Analytes were detected at 254 nm using a UV-VIS detector. The injection volume was 10 µL, and the column temperature was 40°C. The limits of detection and limits of quantification were 63 and 21 µg/L, respectively. Excellent linearity [correlation coefficient (R(2)) = 0.9999] was achieved for EGT quantification in the range of 5-400 mg/L. The relative standard deviations of repeatability, intermediate precision and stability were 1.47, 1.03 and 1.66%, respectively, and EGT recoveries were within 99.2-100.8%. The chromatographic peak corresponding to EGT in the HILIC spectrum was confirmed using ESI-MS. In general, the method developed here is simple, reliable, accurate, and stable and may be useful for routine analyses in EGT biosynthesis research. PMID:26921894

  1. Comparison of Three Reference Methods for Testing Susceptibility of Staphylococci to Trimethoprim-Sulfamethoxazole▿

    PubMed Central

    Griffith, R.; Creely, D.; Revell, P.; Dunne, W. Michael; Shortridge, D.

    2009-01-01

    Three reference MIC methods approved by the Clinical and Laboratory Standards Institute were compared by testing 567 staphylococci against trimethoprim-sulfamethoxazole. Category agreement ranged from 94.9% (broth macrodilution versus broth microdilution) to 98.6% (agar dilution versus broth microdilution). Twenty-seven strains resistant by broth macrodilution were susceptible by broth microdilution. PMID:19741069

  2. Multicenter evaluation of broth microdilution method for susceptibility testing of Cryptococcus neoformans against fluconazole.

    PubMed Central

    Sanati, H; Messer, S A; Pfaller, M; Witt, M; Larsen, R; Espinel-Ingroff, A; Ghannoum, M

    1996-01-01

    We have developed a microdilution method for measuring the susceptibility of Cryptococcus neoformans to fluconazole. The present study evaluated the interlaboratory agreement of the results for the microdilution method obtained at three different sites and compared this method with the National Committee for Clinical Laboratory Standards M27-P reference method. Excellent interlaboratory agreement among the results obtained at the three sites was achieved with this method (83 and 96% agreement within 1 and 2 log2 dilutions, respectively). An overall agreement of 90% between the microdilution method and the M27-P method was observed, demonstrating the comparability of the two methods. However, there are inherent problems with the M27-P method in relation to measuring C. neoformans susceptibility, including suboptimal growth of the organism in RPMI 1640, a longer incubation period, and a narrow range of MICs. On the basis of these data, the microdilution method tested in this study is recommended for inclusion in the National Committee for Laboratory Standards method for testing the antifungal susceptibility of C. neoformans. PMID:8727919

  3. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2004-01-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. Anionic surfactants (SS-6656, Alfoterra 35, 38, 63,65,68) have been identified which can change the wettability of the calcite surface to intermediate/water-wet condition as well or better than the cationic surfactant DTAB with a West Texas crude oil in the presence of Na{sub 2}CO{sub 3}. All the carbonate surfaces (Lithographic Limestone, Marble, Dolomite and Calcite) show similar behavior with respect to wettability alteration with surfactant 4-22. Anionic surfactants (5-166, Alfoterra-33 and Alfoterra-38 and Alfoterra-68), which lower the interfacial tension with a West Texas crude oil to very low values (<10{sup -2} nM/m), have also been identified. Plans for the next quarter include conducting wettability, mobilization, and imbibition studies.

  4. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2003-07-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. We have conducted adsorption, phase behavior and wettability studies. Addition of Na{sub 2}CO{sub 3} decreases IFT with a minimum at about 0.2 M. Addition of surfactant decreases IFT further. In the absence of surfactant the minerals are oil wet after aging with crude oil. Addition of surfactant solution decreases the contact angle to intermediate wettability. Addition of Na{sub 2}CO{sub 3} decreases anionic surfactant adsorption on calcite surface. Plans for the next quarter include conducting adsorption, phase behavior and wettability studies.

  5. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2003-01-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. We have acquired field oil and core samples and field brine compositions from Marathon. We have conducted preliminary adsorption and wettability studies. Addition of Na{sub 2}CO{sub 3} decreases anionic surfactant adsorption on calcite surface. Receding contact angles increase with surfactant adsorption. Plans for the next quarter include conducting adsorption, phase behavior and wettability studies.

  6. Dilute Surfactant Methods for Carbonate Formations

    SciTech Connect

    Kishore K. Mohanty

    2004-03-31

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. Anionic surfactants (Alfoterra 35, 38) recover more than 40% of the oil in about 50 days by imbibition driven by wettability alteration in the core-scale. Anionic surfactant, Alfoterra-68, recovers about 28% of the oil by lower tension aided gravity-driven imbibition in the core-scale. Residual oil saturation showed little capillary number dependence between 10{sup -5} and 10{sup -2}. Wettability alteration increases as the number of ethoxy groups increases in ethoxy sulfate surfactants. Plans for the next quarter include conducting mobilization, and imbibition studies.

  7. Dilute Surfactant Methods for Carbonate Formations

    SciTech Connect

    Kishore K. Mohanty

    2005-10-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the best hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. Laboratory-scale surfactant brine imbibition experiments give high oil recovery (35-62% OOIP) for initially oil-wet cores through wettability alteration and IFT reduction. Core-scale simulation results match those of the experiments. Initial capillarity-driven imbibition gives way to a final gravity-driven process. As the matrix block height increases, surfactant alters wettability to a lesser degree, or permeability decreases, oil production rate decreases. The scale-up to field scale will be further studied in the next quarter.

  8. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2003-07-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. We have conducted adsorption, phase behavior, interfacial tension (IFT) and wettability studies. Addition of Na{sub 2}CO{sub 3} decreases IFT with a minimum at about 0.2 M. Addition of surfactant decreases IFT further. In the absence of surfactant the minerals are oil-wet after aging with crude oil. Addition of surfactant solution decreases the contact angle to intermediate-wet for many surfactants and water-wet for one surfactant. Addition of Na{sub 2}CO{sub 3} decreases anionic surfactant adsorption on calcite surface. Plans for the next quarter include conducting core adsorption, phase behavior, wettability and mobilization studies.

  9. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2004-10-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. Simulation studies indicate that both wettability alteration and gravity-driven flow play significant role in oil recovery from fractured carbonates. Anionic surfactants (Alfoterra 35, 38) recover about 55% of the oil in about 150 days by imbibition driven by wettability alteration and low tension in the core-scale. Anionic surfactant, Alfoterra-68, recovers about 40% of the oil by lower tension aided gravity-driven imbibition in the core-scale. Cationic surfactant, DTAB recovers about 35% of the oil. Plans for the next quarter include conducting simulation and imbibition studies.

  10. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2003-10-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. We have conducted adsorption, phase behavior, interfacial tension (IFT) and wettability studies. Alfoterra-38 (0.05 wt%), Alfoterra-35 (0.05 wt%), SS-6656 (0.05 wt%), and DTAB (1 wt%) altered the wettability of the initially oil-wet calcite plate to an intermediate/water-wet state. Low IFT ({approx}10{sup -3} dynes/cm) is obtained with surfactants 5-166, Alfoterra-33 and Alfoterra-38. Plans for the next quarter include conducting wettability and mobilization studies.

  11. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2005-01-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. Imbibition in an originally oil-wet 2D capillary is the fastest in the case of Alf-38 and slowest in the case of DTAB (among the surfactants studied). Force of adhesion studies and contact angle measurements show that greater wettability alteration is possible with these anionic surfactants than the cationic surfactant studied. The water imbibition rate does not increase monotonically with an increase in the surfactant concentration. A numerical model has been developed that fits the rate of imbibition. Plans for the next quarter include conducting simulation and imbibition studies.

  12. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2005-04-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. Laboratory imbibition tests show about 61% oil recovery in the case of Alf-38 and 37% in the case of DTAB. A numerical model has been developed that fits the rate of imbibition of the laboratory experiment. Field-scale fracture block simulation shows that as the fracture spacing increases, so does the time of recovery. Plans for the next quarter include simulation studies.

  13. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2005-07-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. Laboratory imbibition tests show that imbibition rate is not very sensitive to the surfactant concentration (in the range of 0.05-0.2 wt%) and small amounts of trapped gas saturation. It is however very sensitive to oil permeability and water-oil-ratio. Less than 0.5 M Na2CO3 is needed for in situ soap generation and low adsorption; NaCl can be added to reach the necessary total salinity. The simulation result matches the laboratory imbibition experimental data. Small fracture spacing and high permeability would be needed for high rate of recovery.

  14. Dilute Surfactant Methods for Carbonate Formations

    SciTech Connect

    Kishore K. Mohanty

    2006-02-01

    There are many fractured carbonate reservoirs in US (and the world) with light oil. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). The process of using dilute anionic surfactants in alkaline solutions has been investigated in this work for oil recovery from fractured oil-wet carbonate reservoirs both experimentally and numerically. This process is a surfactant-aided gravity drainage where surfactant diffuses into the matrix, lowers IFT and contact angle, which decrease capillary pressure and increase oil relative permeability enabling gravity to drain the oil up. Anionic surfactants have been identified which at dilute concentration of 0.05 wt% and optimal salinity can lower the interfacial tension and change the wettability of the calcite surface to intermediate/water-wet condition as well or better than the cationic surfactant DTAB with a West Texas crude oil. The force of adhesion in AFM of oil-wet regions changes after anionic surfactant treatment to values similar to those of water-wet regions. The AFM topography images showed that the oil-wetting material was removed from the surface by the anionic surfactant treatment. Adsorption studies indicate that the extent of adsorption for anionic surfactants on calcite minerals decreases with increase in pH and with decrease in salinity. Surfactant adsorption can be minimized in the presence of Na{sub 2}CO{sub 3}. Laboratory-scale surfactant brine imbibition experiments give high oil recovery (20-42% OOIP in 50 days; up to 60% in 200 days) for initially oil-wet cores through wettability alteration and IFT reduction. Small (<10%) initial gas saturation does not affect significantly the rate of oil recovery in the imbibition process, but larger gas saturation decreases the oil recovery rate. As the core permeability decreases, the rate of oil recovery reduces

  15. Final report from the Committee on Antimicrobial Susceptibility Testing, Japanese Society of Chemotherapy, on the agar dilution method (2007).

    PubMed

    Nagayama, Ariaki; Yamaguchi, Keizo; Watanabe, Kunitomo; Tanaka, Masatoshi; Kobayashi, Intetsu; Nagasawa, Zenzo

    2008-10-01

    In 1968, the agar dilution method was developed as an independent Japanese method for measuring the minimal inhibitory concentration (MIC) of antimicrobial agents. As this method differed in a few respects from the MIC measurement methods used in other countries, it was revised in 1981, by a committee headed by Susumu Mitsuhashi, and the revised method (Chemotherapy 29:76-79, 1981) has been used since then. In 1979, an agar dilution method for measuring the MIC of anaerobes was developed by a committee chaired by Nozomu Kosakai (Chemotherapy 27:559-561, 1979). In 1990, a committee headed by Sachiko Goto approved a broth microdilution method for nonfastidious bacteria (Chemotherapy 38:102-105, 1990). Later, a committee headed by Atsushi Saito examined media that would be suitable for nonfastidious bacteria and fastidious bacteria, and they endeavored to prepare a broth microdilution method for anaerobic bacteria. In this context, a new broth microdilution method was proposed at the 40th Annual Meeting of the Japanese Society of Chemotherapy (JSC) in Nagoya in 1992, and the proposal was adopted as the standard JSC method after some modification (Chemotherapy 41: 183-189, 1993). The agar dilution method has remained unrevised for approximately 20 years. A proposal to review this method was recently made, and the 2007 Committee on Antimicrobial Susceptibility Testing was formed, comprising the JSC members listed below. Under the auspices of this committee, the method revised in 1981 was reviewed in comparison to the international standard method (Clinical and Laboratory Standards Institute [CLSI] method). PMID:18936894

  16. In vitro susceptibility tests for cationic peptides: comparison of broth microdilution methods for bacteria that grow aerobically.

    PubMed

    Giacometti, A; Cirioni, O; Barchiesi, F; Del Prete, M S; Fortuna, M; Caselli, F; Scalise, G

    2000-06-01

    The in vitro susceptibilities of 90 clinical isolates of gram-positive and gram-negative aerobic bacteria to six cationic peptides, buforin II, cecropin P1, indolicidin, magainin II, nisin, and ranalexin, were evaluated by two broth microdilution methods. The first method was performed according to the procedures outlined by the National Committee for Clinical Laboratory Standards for bacteria that grow aerobically, while the second was performed according to the procedures recently proposed by the R. E. W. Hancock laboratory for testing antimicrobial peptides. Overall, the first method produced MICs two- and fourfold higher than the second method. PMID:10817731

  17. [Assessment of 2 automated microdilution techniques compared to an agar dilution method in determining sensitivity to fosfomycin in strains of carbapenem-resistant Pseudomonas aeruginosa].

    PubMed

    Gil-Romero, Yolanda; Regodón-Domínguez, Marta; Wilhelmi de Cal, Isabel; López-Fabal, Fátima; Gómez-Garcés, José Luis

    2016-01-01

    Carbapenems-resistance in Pseudomonas aeruginosa isolates has been widely reported. Fosfomycin has been shown to act synergistically with other antimicrobials. The agar dilution method was approved for susceptibility testing for fosfomycin and Pseudomonas aeruginosa. However, broth microdilution methods are the basis of systems currently used in clinical microbiology laboratories. The results of this study indicate that these methods are acceptable as susceptibility testing methods for fosfomycin against these organisms. PMID:26620604

  18. Thymoquinone vapor significantly affects the results of Staphylococcus aureus sensitivity tests using the standard broth microdilution method.

    PubMed

    Novy, Pavel; Kloucek, Pavel; Rondevaldova, Johana; Havlik, Jaroslav; Kourimska, Lenka; Kokoska, Ladislav

    2014-04-01

    The broth microdilution (BMD) method is widely used for the determination of minimum inhibitory concentrations of antimicrobial agents, including volatile oils and their components. In this series of various experiments, we have demonstrated the influence of thymoquinone (TQ) vapor on the results of the BMD test performed with Staphylococcus aureus as a model organism. The spread of vapor from the TQ containing wells (32-512 μg/mL) caused the complete inhibition of staphylococcal growth in adjoining wells initially containing bacterium-inoculated pure Mueller-Hinton broth only and thus produced false positive results of the test. The ability of TQ to pass into the adjoined wells was subsequently confirmed by gas chromatography-mass spectrometry, whereas TQ at concentrations up to 84 μg/mL was detected in these wells after five hours. Based on these results, we suppose that vapors of TQ as well as of other naturally occurring volatile compounds and their mixtures (for example essential oils and plant extracts) can significantly influence results of the standard BMD assay. These observations, therefore, call for development of new appropriate BMD method suitable for assessment of antimicrobial activity of volatile substances. PMID:24508861

  19. Improved Broth Microdilution Method for Antimicrobial Susceptibility Testing of Francisella Noatunensis Orientalis.

    PubMed

    Soto, Esteban; Halliday-Simmonds, Iona; Francis, Stewart; Fraites, Trellor; Martínez-López, Beatriz; Wiles, Judy; Hawke, John P; Endris, Richard D

    2016-09-01

    In this project we optimized a minimal inhibitory concentration testing protocol for Francisella noatunensis orientalis. Thirty-three F. noatunensis orientalis isolates recovered from different fish species and locations were tested, and Escherichia coli ATCC 25922 was used as a quality control reference strain. A modified cation-adjusted Mueller Hinton broth supplemented with 2% IsoVitalex and 0.1% glucose (MMH) was tested at a pH of 6.4 ± 0.1, 7.1 ± 0.1, and 7.3 ± 0.1. Growth curves generated for F. noatunensis orientalis indicated that MMH at a pH of 6.4 ± 0.1 provided optimal growth. There were no significant differences in the growth curves obtained from isolates recovered from different fish species or from fresh or marine water. The pH of 6.4 ± 0.1 in the MMH media interfered with the inhibitory properties of the potentiated sulfonamides (ormetoprim-sulfadimethoxine and trimethoprim-sulfamethoxazole) when using the E. coli ATCC reference strain. Minimal inhibitory concentrations of eight antimicrobials (gentamicin, enrofloxacin, ampicillin, oxytetracycline, erythromycin, florfenicol, flumequine, and oxolinic acid) were similar for all F. noatunensis orientalis isolates. The in vitro susceptibility data provided here can provide a baseline for monitoring the development of antimicrobial resistance among F. noatunensis orientalis isolates, as well as provide valuable data in the development of potential therapeutics. Received October 27, 2015; accepted April 13, 2016. PMID:27484609

  20. Evaluation of two gas-dilution methods for instrument calibration

    NASA Technical Reports Server (NTRS)

    Evans, A., Jr.

    1977-01-01

    Two gas dilution methods were evaluated for use in the calibration of analytical instruments used in air pollution studies. A dual isotope fluorescence carbon monoxide analyzer was used as the transfer standard. The methods are not new but some modifications are described. The rotary injection gas dilution method was found to be more accurate than the closed loop method. Results by the two methods differed by 5 percent. This could not be accounted for by the random errors in the measurements. The methods avoid the problems associated with pressurized cylinders. Both methods have merit and have found a place in instrument calibration work.

  1. Indirect methods for characterization of carbon dioxide levels in fermentation broth.

    PubMed

    Frick, R; Junker, B

    1999-01-01

    Various factors which influence dissolved carbon dioxide levels were indirectly evaluated in pilot scale and laboratory studies. For pilot scale studies, off-gas carbon dioxide (percentage in exit air) was measured using a mass spectrometer and then its potential impact on dissolved carbon dioxide concentrations qualitatively examined. Greater volumetric air flowrates reduced off-gas carbon dioxide levels more effectively at lower airflow ranges and thus lowered expected dissolved carbon dioxide levels through gas stripping. Lower broth pH values decreased off-gas carbon dioxide levels but increased expected dissolved carbon dioxide levels due to the pH-dependence of the gas/liquid carbon dioxide equilibrium. While back-pressure increases had an insignificant effect on off-gas carbon dioxide levels, they directly affected expected dissolved carbon dioxide levels according to Henry's law. Laboratory studies, conducted using both uninoculated and inoculated fermentation media, quantified the response of the media to pH changes with bicarbonate addition, specifically its buffering capacity. This effect then was related qualitatively to expected dissolved carbon dioxide levels. Higher dissolved carbon dioxide levels, as demonstrated by reduced pH changes with bicarbonate addition, thus would be expected for salt solutions of increased ionic strength and higher protein content media. In addition, pH changes with greater bicarbonate additions declined for fermentation samples taken over the course of a one week cultivation, most likely due to the higher protein content associated with biomass growth. The presence of weak acids/bases initially in the media or formed as metabolic by products, as well as the concentration of buffering ions such as phosphate, also were believed to be important contributing elements to the buffering capacity of the solution. PMID:16232479

  2. Simplified Method for Groundwater Treatment Using Dilution and Ceramic Filter

    NASA Astrophysics Data System (ADS)

    Musa, S.; Ariff, N. A.; Kadir, M. N. Abdul; Denan, F.

    2016-07-01

    Groundwater is one of the natural resources that is not susceptible to pollutants. However, increasing activities of municipal, industrial, agricultural or extreme land use activities have resulted in groundwater contamination as occured at the Research Centre for Soft Soil Malaysia (RECESS), Universiti Tun Hussein Onn Malaysia (UTHM). Thus, aims of this study is to treat groundwater by using rainwater and simple ceramic filter as a treatment agent. The treatment uses rain water dilution, ceramic filters and combined method of dilute and filtering as an alternate treatment which are simple and more practical compared to modern or chemical methods. The water went through dilution treatment processes able to get rid of 57% reduction compared to initial condition. Meanwhile, the water that passes through the filtering process successfully get rid of as much as 86% groundwater parameters where only chloride does not pass the standard. Favorable results for the combination methods of dilution and filtration methods that can succesfully eliminate 100% parameters that donot pass the standards of the Ministry of Health and the Interim National Drinking Water Quality Standard such as those found in groundwater in RECESS, UTHM especially sulfate and chloride. As a result, it allows the raw water that will use clean drinking water and safe. It also proves that the method used in this study is very effective in improving the quality of groundwater.

  3. Evaluation of minimal inhibitory concentration of two new materials using tube dilution method: An in vitro study

    PubMed Central

    Hiremath, Geeta S.; Kulkarni, Raghavendra D.; Naik, Balaram D.

    2015-01-01

    Aim: The aim of the study is to evaluate and compare the antimicrobial efficacy of two new materials MTA Plus and Biodentine with ProRoot MTA using tube dilution method. Materials and Methods: The materials used were ProRoot MTA (Dentsply), MTA Plus (compounded by Prevest Denpro, Jammu, India for Avalon Biomed Inc, USA) and a calcium silicate based material Biodentine (Septodont, Saint-Maur-des-Fosses, France). Doubling dilutions of the material were prepared in Sabouraud's dextrose broth (SDB) and Brain Heart Infusion (BHI) broth for Candida albicans and Enterococcus faecalis, respectively. The minimal concentration at which inhibition of microorganism occurred was measured and noted as minimal inhibitory concentration (MIC) of the material. Results: There was no statistically significant difference between the materials against C. albicans. Biodentine was statistically significant than MTA Plus against E. faecalis (P-value-0.022). ProRoot MTA was statistically significant at different time intervals against E. faecalis (P-value-0.001). Conclusion: ProRoot MTA and Biodentine proved to have antimicrobial property. MTA Plusproved as a good antifungal agent. PMID:25829698

  4. Variability of β-lactam susceptibility testing for Streptococcus pneumoniae using 4 commercial test methods and broth microdilution.

    PubMed

    Charles, Marthe K; Berenger, Byron M; Turnbull, LeeAnn; Rennie, Robert; Fuller, Jeff

    2016-03-01

    Limited data are available that verify the performance of commercial susceptibility methods for Streptococcus pneumoniae following the 2008 Clinical and Laboratory Standards Institute revision of the β-lactam breakpoints. We compared the performance of Etest, M.I.C. Evaluator (M.I.C.E), Vitek, and Sensititre systems to broth microdilution for S. pneumoniae susceptibility testing of penicillin, ceftriaxone, meropenem, and amoxicillin. Essential agreement was ≥90% for the majority of the β-lactams and methods tested, particularly for penicillin and ceftriaxone. Categorical agreements (CAs) for penicillin using meningeal and nonmeningeal breakpoints were ≥90%; CAs using penicillin oral breakpoints were 84-89%. Ceftriaxone CAs using nonmeningeal and meningeal breakpoints were 68-88% for Etest, M.I.C.E., and Vitek2 with 6-12% very major errors (VMEs) using meningeal breakpoints. Sensititre CAs for ceftriaxone, amoxicillin, and meropenem were ≥90% with no VMEs. In the context of the current guidelines, there exists considerable method-dependent variability in the susceptibility of S. pneumoniae to β-lactams. PMID:26707068

  5. In Vitro Susceptibility of Candida Species to Four Antifungal Agents Assessed by the Reference Broth Microdilution Method

    PubMed Central

    Eksi, Fahriye; Gayyurhan, Efgan Dogan; Balci, Iclal

    2013-01-01

    This study was performed to determine the distribution of Candida species isolated from the blood cultures of the patients hospitalized in our hospital and to investigate their antifungal susceptibility. Candida strains were identified at species level by using classical methods and API ID 32C (bioMerieux, France) identification kits. The susceptibility of the strains to amphotericin B, fluconazole, voriconazole, and caspofungin was evaluated by using the reference broth microdilution method in document M27-A3 of the Clinical and Laboratory Standards Institute. Of the 111 Candida strains isolated, 47.7% were identified as C. albicans and 52.3% as non-albicans Candida strains. The MIC ranges were 0.03–1 μg/mL for amphotericin B, 0.125–≥64 μg/mL for fluconazole, 0.03–16 μg/mL for voriconazole, and 0.015–0.25 μg/mL for caspofungin. All Candida strains were susceptible to amphotericin B and caspofungin. 10.8% isolates were resistant to fluconazole and 8.1% isolates were dose-dependent susceptible. While 0.9% isolate was resistant to voriconazole, 0.9% isolate was dose-dependent susceptible. In our study, C. albicans and C. parapsilosis were the most frequently encountered agents of candidemia and it was detected that voriconazole with a low resistance rate might also be used with confidence in the treatment of infections occurring with these agents, primarily besides amphotericin B and caspofungin. PMID:24250260

  6. Methods for broth dilution susceptibility testing of bacteria isolated from aquatic animals; approved guideline-second edition

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Antimicrobial susceptibility testing is recommended to determine which antimicrobial agents should be considered for treating a bacterial pathogen. Many bacteria that cause disease in aquatic animals require growth conditions that vary substantially from routine terrestrial pathogens. It has thus ...

  7. Comparison of three DNA preparation methods for real-time polymerase chain reaction confirmation of Mycobacterium avium subsp. paratuberculosis growth in an automated broth culture system.

    PubMed

    Sweeney, Raymond W; Whitlock, Robert H; McAdams, Susan C

    2006-11-01

    Three methods of harvesting DNA from broth culture tubes for quantitative real-time polymerase chain reaction (qrtPCR) confirmation of Mycobacterium avium subsp. paratuberculosis (MAP) were evaluated. A commercial DNA extraction kit, the boil method (boiling for 5 minutes), or direct addition of broth culture media to the PCR reaction mix were tested. Samples were evaluated at 8 or 11 days of incubation and at the time of instrument-signal culture-positive. In total, when tested at time to instrument signal positive, 10/10 (100%) of samples extracted by the commercial method were positive on qrtPCR, whereas 9/10 (90%) were positive after the boil method, and 6/10 (60%) were positive after the direct method. Increased volumes of egg-yolk emulsion added to the culture tubes prolonged the number of cycles to threshold positive for the samples that were not subjected to commercial extraction or boiling. Samples were not reliably positive when tested at 8 or 11 days of incubation. The boil method appears to represent a reasonable time- and money-saving method to harvest DNA for qrtPCR confirmation of MAP in broth culture at time to instrument signal positive. PMID:17121088

  8. In Vitro Amphotericin B Susceptibility of Malassezia pachydermatis Determined by the CLSI Broth Microdilution Method and Etest Using Lipid-Enriched Media

    PubMed Central

    Álvarez-Pérez, Sergio; Peláez, Teresa; Cutuli, Maite; García, Marta E.

    2014-01-01

    We determined the in vitro amphotericin B susceptibility of 60 Malassezia pachydermatis isolates by the CLSI broth microdilution method and the Etest using lipid-enriched media. All isolates were susceptible at MICs of ≤1 μg/ml, confirming the high activity of amphotericin B against this yeast species. Overall, the essential agreement between the tested methods was high (80% and 96.7% after 48 h and 72 h, respectively), and all discrepancies were regarded as nonsubstantial. PMID:24752258

  9. Comparative evaluation of macrodilution and alamar colorimetric microdilution broth methods for antifungal susceptibility testing of yeast isolates.

    PubMed Central

    To, W K; Fothergill, A W; Rinaldi, M G

    1995-01-01

    A comparative evaluation of the macrodilution method and the Alamar colorimetric method for the susceptibility testing of amphotericin B, fluconazole, and flucytosine was conducted with 134 pathogenic yeasts. The clinical isolates included 28 Candida albicans, 17 Candida tropicalis, 15 Candida parapsilosis, 12 Candida krusei, 10 Candida lusitaniae, 9 Candida guilliermondii, 18 Torulopsis glabrata, and 25 Cryptococcus neoformans isolates. The macrodilution method was performed and interpreted according to the recommendations of the National Committee for Clinical Laboratory Standards (document M27-P), and the Alamar colorimetric method was performed according to the manufacturer's instructions. For the Alamar colorimetric method, MICs were determined at 24 and 48 h of incubation for Candida species and T. glabrata and at 48 and 72 h of incubation for C. neoformans. The overall agreement within +/- 1 dilution for Candida species and T. glabrata against the three antifungal agents was generally good, with the values for amphotericin B, fluconazole, and flucytosine being 85.3, 77.9, and 86.2%, respectively, at the 24-h readings and 69.3, 65.2, and 97.2%, respectively, at the 48-h readings. Most disagreement was noted with fluconazole against C. tropicalis and T. glabrata. Our studies indicate that determination of MICs at 24 h by the Alamar colorimetric method is a valid alternate method for testing amphotericin B, fluconazole, and flucytosine against Candida species but not for testing fluconazole against C. tropicalis and T. glabrata. For flucytosine, much better agreement can be demonstrated against Candida species and T. glabrata at the 48-h readings by the Alamar method.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8567901

  10. Evaluation of the broth microdilution method using 2,3-diphenyl-5-thienyl-(2)-tetrazolium chloride for rapidly growing mycobacteria susceptibility testing.

    PubMed

    Lee, Sun Min; Kim, Jeong man; Jeong, Joseph; Park, Young Kil; Bai, Gill-Han; Lee, Eun Yup; Lee, Min Ki; Chang, Chulhun L

    2007-10-01

    As the incidence of nontuberculous mycobacterial infection has been increasing recently in Korea, the importance of drug susceptibility test for clinical isolates of mycobacteria has become larger. In this study we determined the antimicrobial susceptibility patterns of clinical isolates of M. fortuitum and M. abscessus in Korea, and evaluated the efficacy of a modified broth microdilution method using 2,3-diphenyl-5-thienyl-(2)-tetrazolium chloride (STC), in terms of its ability to provide accurate and easy-to-read minimal inhibitory concentration (MIC) endpoints for the susceptibility testing of rapidly growing mycobacteria. Most isolates of M. fortuitum and M. abscessus in Korea are susceptible or intermediately susceptible to amikacin, cefoxitin, ciprofloxacin, and clarithromycin. Many isolates of M. fortuitum are susceptible to doxycycline, sulfamethoxazole, and imipenem, while many M. abscessus isolates are resistant to these drugs. In the present study, the modified broth microdilution method using STC was found to be reliable, easy to read, and inexpensive for M. fortuitum and M. abscessus susceptibility testing. The modified colorimetric MIC testing method using STC was proven to be a useful surrogate for RGM antibiotic susceptibility testing. PMID:17982223

  11. Evaluation of PCR inhibitory effect of enrichment broths and comparison of DNA extraction methods for detection of Salmonella Enteritidis using real-time PCR assay.

    PubMed

    Hyeon, Ji Yeon; Hwang, In Gyun; Kwak, Hyo Sun; Park, Chankyu; Choi, In Soo; Seo, Kun Ho

    2010-06-01

    The best enrichment broth and DNA extraction scheme was determined for rapid and sensitive detection of Salmonella Enteritidis in steamed pork using real-time PCR. The inhibitory effect of commonly used Salmonella enrichment broths, Rappaport-Vassiliadis (RV) and Muller-Kauffmann tetrathionate with novobiocin (MKTTn), on real-time PCR was confirmed. The inhibition of PCR was statistically significant (p < 0.05) in RV and MKTTn, as compared with buffered peptone water (BPW) or phosphate-buffered saline. The inhibitory effect of the selective enrichment media was successfully removed by using a modified DNA extraction, PrepMan Ultra Reagent with an additional washing step or the DNeasy Tissue Kit. In three experiments, when applied to detection of Salmonella Enteritidis in steamed pork, the real-time PCR coupled with single 24 h enrichment with BPW performed better than double 48 h enrichment with BPW plus RV or MKTTn. The simple real-time PCR assay using BPW proved to be a rapid and sensitive test for detection of low concentrations of Salmonella Enteritidis in steamed pork samples as compared with the conventional culture method. PMID:20458155

  12. Quantifying Methane Fluxes Simply and Accurately: The Tracer Dilution Method

    NASA Astrophysics Data System (ADS)

    Rella, Christopher; Crosson, Eric; Green, Roger; Hater, Gary; Dayton, Dave; Lafleur, Rick; Merrill, Ray; Tan, Sze; Thoma, Eben

    2010-05-01

    Methane is an important atmospheric constituent with a wide variety of sources, both natural and anthropogenic, including wetlands and other water bodies, permafrost, farms, landfills, and areas with significant petrochemical exploration, drilling, transport, or processing, or refining occurs. Despite its importance to the carbon cycle, its significant impact as a greenhouse gas, and its ubiquity in modern life as a source of energy, its sources and sinks in marine and terrestrial ecosystems are only poorly understood. This is largely because high quality, quantitative measurements of methane fluxes in these different environments have not been available, due both to the lack of robust field-deployable instrumentation as well as to the fact that most significant sources of methane extend over large areas (from 10's to 1,000,000's of square meters) and are heterogeneous emitters - i.e., the methane is not emitted evenly over the area in question. Quantifying the total methane emissions from such sources becomes a tremendous challenge, compounded by the fact that atmospheric transport from emission point to detection point can be highly variable. In this presentation we describe a robust, accurate, and easy-to-deploy technique called the tracer dilution method, in which a known gas (such as acetylene, nitrous oxide, or sulfur hexafluoride) is released in the same vicinity of the methane emissions. Measurements of methane and the tracer gas are then made downwind of the release point, in the so-called far-field, where the area of methane emissions cannot be distinguished from a point source (i.e., the two gas plumes are well-mixed). In this regime, the methane emissions are given by the ratio of the two measured concentrations, multiplied by the known tracer emission rate. The challenges associated with atmospheric variability and heterogeneous methane emissions are handled automatically by the transport and dispersion of the tracer. We present detailed methane flux

  13. Detection of amphotericin B resistance in Candida haemulonii and closely related species by use of the Etest, Vitek-2 yeast susceptibility system, and CLSI and EUCAST broth microdilution methods.

    PubMed

    Shin, Jong Hee; Kim, Mi-Na; Jang, Sook Jin; Ju, Min Young; Kim, Soo Hyun; Shin, Myung Geun; Suh, Soon Pal; Ryang, Dong Wook

    2012-06-01

    The emerging fungal pathogens Candida haemulonii and Candida pseudohaemulonii often show high-level resistance to amphotericin B (AMB). We compared the utilities of five antifungal susceptibility testing methods, i.e., the Etest using Mueller-Hinton agar supplemented with glucose and methylene blue (Etest-MH), the Etest using RPMI agar supplemented with glucose (Etest-RPG), the Vitek-2 yeast susceptibility system, and the Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) broth microdilution methods, for the detection of AMB-resistant isolates of C. haemulonii and closely related species. Thirty-eight clinical isolates (8 C. haemulonii, 10 C. pseudohaemulonii, and 20 Candida auris isolates) were analyzed. Of the 18 C. haemulonii and C. pseudohaemulonii isolates, 18, 15, 18, 10, and 9 exhibited AMB MICs of >1 μg/ml by the Etest-MH, Etest-RPG, Vitek-2, CLSI, and EUCAST methods, respectively. All 20 C. auris isolates showed AMB MICs of ≤1 μg/ml by all five methods. Of the methods, the Etest-MH generated the broadest distribution of AMB MICs for all 38 isolates and showed the best discrimination between the C. haemulonii and C. pseudohaemulonii isolates (4 to 32 μg/ml) and those of C. auris (0.125 to 0.5 μg/ml). Taking the Etest-MH as the reference method, the essential agreements (within two dilutions) for the Etest-RPG, Vitek-2, CLSI, and EUCAST methods were 84, 92, 55, and 55%, respectively; the categorical agreements were 92, 92, 79, and 76%, respectively. This study provides the first data on the efficacy of the Etest-MH and its excellent agreement with Vitek-2 for discriminating AMB-resistant from AMB-susceptible isolates of these Candida species. PMID:22442324

  14. Tracer-dilution method indicates flowrate through compressor

    SciTech Connect

    Lagus, P.L.; Flanagan, B.S. ); Peterson, M.E. ); Clowney, S.L. )

    1991-02-25

    A technique for measuring compressor flowrate through an operating natural-gas centrifugal compressor has been tested and found to have a precisions approaching {plus minus}1.5%. The technique employs constant-flow tracer dilution. Testing demonstrated that use of a critical-flow nozzle to inject a constant, known flow of tracer into a flowing natural-gas stream is feasible. Effects of potential pulsation on a tracer flow measurement appear to be eliminated by this technique. With experimental and operational streamlining, the constant-flow tracer dilution technique is capable of being used to measure the flowrate through operating centrifugal compressors with sufficient precisions and accuracy to allow compressor operating characteristics to be determined. This technique is especially useful in situations in which an orifice-flow measurement cannot be performed because of physical space limits or economic considerations.

  15. Comparison of the EUCAST and CLSI Broth Microdilution Methods for Testing Isavuconazole, Posaconazole, and Amphotericin B against Molecularly Identified Mucorales Species

    PubMed Central

    Singh, Pradeep Kumar; Kathuria, Shallu; Hagen, Ferry; Meis, Jacques F.

    2015-01-01

    We compared EUCAST and CLSI antifungal susceptibility testing (AFST) methods for triazoles and amphotericin B against 124 clinical Mucorales isolates. The EUCAST method yielded MIC values 1- to 3-fold dilutions higher than those of the CLSI method for amphotericin B. The essential agreements between the two methods for triazoles were high, i.e., 99.1% (voriconazole), 98.3% (isavuconazole), and 87% (posaconazole), whereas it was significantly lower for amphotericin B (66.1%). Strategies for harmonization of the two methods for Mucorales AFST are warranted. PMID:26438489

  16. Activities of Tedizolid and Linezolid Determined by the Reference Broth Microdilution Method against 3,032 Gram-Positive Bacterial Isolates Collected in Asia-Pacific, Eastern Europe, and Latin American Countries in 2014.

    PubMed

    Pfaller, Michael A; Flamm, Robert K; Jones, Ronald N; Farrell, David J; Mendes, Rodrigo E

    2016-09-01

    Tedizolid and linezolid in vitro activities against 3,032 Gram-positive pathogens collected in Asia-Pacific, Eastern European, and Latin American medical centers during 2014 were assessed. The isolates were tested for susceptibility by the current reference broth microdilution methods. Due to concern over the effect of MIC endpoint criteria on the results of testing the oxazolidinones tedizolid and linezolid, MIC endpoint values were read by two methods: (i) reading the MIC at the first well where the trailing began without regard for pinpoint trailing, according to CLSI M07-A10 and M100-S26 document instructions for reading linezolid (i.e., 80% inhibition of growth; these reads were designated tedizolid 80 and linezolid 80), and (ii) at 100% inhibition of growth (designated tedizolid 100 and linezolid 100). All Staphylococcus aureus, Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus anginosus group, and Enterococcus faecalis isolates were inhibited at tedizolid 80 and 100 MIC values of 0.25 and 0.5, 0.25 and 0.25, 0.25 and 0.5, 0.12 and 0.25, and 0.5 and 1 μg/ml, respectively. Generally, MIC50 and MIC90 results for tedizolid 80 and linezolid 80 were one doubling dilution lower than those read at 100% inhibition. Tedizolid was 4- to 8-fold more potent than linezolid against all the isolates tested regardless of the MIC endpoint criterion used. Despite the differences in potency, >99.9% of isolates tested in this survey were susceptible to both linezolid and tedizolid using CLSI and EUCAST interpretive criteria. In conclusion, tedizolid demonstrated greater in vitro potency than linezolid against Gram-positive pathogens isolated from patients in medical centers across the Asia-Pacific region, Eastern Europe, and Latin America. PMID:27353270

  17. Reducing the matrix effects in chemical analysis: fusion of isotope dilution and standard addition methods

    NASA Astrophysics Data System (ADS)

    Pagliano, Enea; Meija, Juris

    2016-04-01

    The combination of isotope dilution and mass spectrometry has become an ubiquitous tool of chemical analysis. Often perceived as one of the most accurate methods of chemical analysis, it is not without shortcomings. Current isotope dilution equations are not capable of fully addressing one of the key problems encountered in chemical analysis: the possible effect of sample matrix on measured isotope ratios. The method of standard addition does compensate for the effect of sample matrix by making sure that all measured solutions have identical composition. While it is impossible to attain such condition in traditional isotope dilution, we present equations which allow for matrix-matching between all measured solutions by fusion of isotope dilution and standard addition methods.

  18. First comprehensive evaluation of the M.I.C. evaluator device compared to Etest and CLSI reference dilution methods for antimicrobial susceptibility testing of clinical strains of anaerobes and other fastidious bacterial species.

    PubMed

    Rennie, R P; Turnbull, L; Brosnikoff, C; Cloke, J

    2012-04-01

    The new M.I.C. Evaluator strip uses test methodology and the recording of results that are similar to those of Etest. For this first assessment, 102 clinical strains of anaerobic bacteria from 12 genera and 155 strains from 7 genera and 8 species of fastidious bacteria were tested by M.I.C. Evaluator, Etest, and agar dilution or broth microdilution as a reference standard. Ampicillin, amoxicillin, amoxicillin-clavulanate, cefotaxime, ciprofloxacin, erythromycin, imipenem, levofloxacin, metronidazole, penicillin, and tetracycline were tested depending on the species. Agar dilution for anaerobes was performed according to CLSI document M11-A7. For the fastidious bacteria, CLSI document M45-A2 was followed. For the anaerobes, essential and categorical agreement between M.I.C. Evaluator and Etest was >90%. Compared to agar dilution, essential agreement was low for both strip tests, and many very major errors were observed for metronidazole (13 to 14%) and penicillin (8 to 9%) with isolates from the Bacteroides fragilis group and Clostridium species. For fastidious species, essential agreements for M.I.C. Evaluator and Etest plus or minus one doubling dilution were >95%. Compared to broth microdilution, essential agreements were low (40 to 90%) plus or minus one dilution and were >90% plus or minus two dilutions, with high overall category agreement (CA). Major and minor errors were within established parameters for all strains tested. The M.I.C. Evaluator strips were equivalent to Etest for anaerobes and fastidious species. These observations require further investigation to determine which methods provide the most accurate MIC for clinical utility. The further evaluation of additional M.I.C. Evaluator agents will be performed as they become available. PMID:22238439

  19. Initial use of a broth microdilution method suitable for in vitro testing of fungal isolates in a clinical microbiology laboratory.

    PubMed Central

    Hacek, D M; Noskin, G A; Trakas, K; Peterson, L R

    1995-01-01

    Antifungal susceptibility testing methods currently lack a standardized procedure. Many factors, such as inoculum preparation, inoculum density, medium selection, pH, incubation time and temperature, and endpoint determination, affect results. We developed a workable procedure for fungal susceptibility testing, with a microtiter method based upon modifications of the proposed guidelines from the National Committee for Clinical Laboratory Standards, using two different growth media. For this procedure, the microtiter tray is prepared as a panel of 6 drugs (amphotericin B, flucytosine, fluconazole, ketoconazole, miconazole, and itraconazole) alone and in combination with amphotericin B. Eagle's minimal essential medium and RPMI 1640 are the two growth media. Two separate susceptibility trays are inoculated for each sensitivity test, with one tray incubated at 30 degrees C and the other incubated at 35 degrees C. After 48 h of growth, results for both temperatures and both media are recorded and interpreted. The four test environments (two media each at two temperatures) provided growth for 100 of the first 104 organisms that were submitted for testing. This approach provides a workable methodology for routine antifungal susceptibility testing in a clinical microbiology laboratory setting. PMID:7665664

  20. Antifungal susceptibility of Malassezia furfur, Malassezia sympodialis, and Malassezia globosa to azole drugs and amphotericin B evaluated using a broth microdilution method.

    PubMed

    Rojas, Florencia D; Sosa, María de los A; Fernández, Mariana S; Cattana, María E; Córdoba, Susana B; Giusiano, Gustavo E

    2014-08-01

    We studied the in vitro activity of fluconazole (FCZ), ketoconazole (KTZ), miconazole (MCZ), voriconazole (VCZ), itraconazole (ITZ) and amphotericin B (AMB) against the three major pathogenic Malassezia species, M. globosa, M. sympodialis, and M. furfur. Antifungal susceptibilities were determined using the broth microdilution method in accordance with Clinical and Laboratory Standards Institute reference document M27-A3. To support lipid-dependent yeast development, glucose, peptone, ox bile, malt extract, glycerol, and Tween supplements were added to Roswell Park Memorial Institute RPMI 1640 medium. The supplemented medium allowed good growth of all three species studied. The minimal inhibitory concentrations (MICs) were recorded after 72 h of incubation at 32ºC. The three species showed different susceptibility profiles for the drugs tested. Malassezia sympodialis was the most susceptible and M. furfur the least susceptible species. KTZ, ITZ, and VCZ were the most active drugs, showing low variability among isolates of the same species. FCZ, MCZ, and AMB showed high MICs and wide MIC ranges. Differences observed emphasize the need to accurately identify and evaluate antifungal susceptibility of Malassezia species. Further investigations and collaborative studies are essential for correlating in vitro results with clinical outcomes since the existing limited data do not allow definitive conclusions. PMID:24965946

  1. Tests of the critical assumptions of the dilution method for estimating bacterivory by microeucaryotes.

    PubMed

    Tremaine, S C; Mills, A L

    1987-12-01

    The critical assumptions of the dilution method for estimating grazing rates of microzooplankton were tested by using a community from the sediment-water interface of Lake Anna, Va. Determination of the appropriate computational model was achieved by regression analysis; the exponential model was appropriate for bacterial growth at Lake Anna. The assumption that the change in grazing pressure is linearly proportional to the dilution factor was tested by analysis of variance with a lack-of-fit test. There was a significant (P < 0.0001) linear (P > 0.05) relationship between the dilution factor and time-dependent change in ln bacterial abundance. The assumption that bacterial growth is not altered by possible substrate enrichment in the dilution treatment was tested by amending diluted water with various amounts of dissolved organic carbon (either yeast extract or extracted carbon from lake sediments). Additions of carbon did not significantly alter bacterial growth rates during the incubation period (24 h). On the basis of these results, the assumptions of the dilution method proved to be valid for the system examined. PMID:16347507

  2. Different antimicrobial susceptibility testing methods to detect ertapenem resistance in Enterobacteriaceae: VITEK2, MicroScan, Etest, disk diffusion, and broth microdilution.

    PubMed

    Lee, Miae; Chung, Hae-Sun

    2015-05-01

    We investigated different antimicrobial susceptibility testing methods to detect ertapenem resistance in Enterobacteriaceae. A total of 72 Enterobacteriaceae isolates were collected from a clinical microbiology laboratory of a tertiary university hospital, all of which were detected ertapenem resistance by the VITEK2 system. Bacterial identification and antimicrobial susceptibility were determined using the VITEK2. Ertapenem susceptibility test was performed using the MicroScan, Etest and a disk diffusion test. Ertapenem MICs were confirmed using the broth microdilution (BMD). Sensitivity, specificity, and positive and negative predictive values (PPV and NPV, respectively) of each method for the detection of ertapenem resistance were calculated. Carbapenemases and AmpC β-lactamase were screened using phenotypic methods. Among the 72 isolates, 20 isolates (27.8%) were resistant to ertapenem. Etest showed high sensitivity and specificity (85.0% and 88.5%, respectively) and excellent concordance with BMD. The disk diffusion test had the lowest sensitivity of 50.0%. The VITEK2 showed the lowest essential and categorical agreement (30.5% and 27.8%, respectively). The MicroScan showed relatively good agreement with BMD compared to the VITEK2. Most category disagreements were minor errors. There were 3 very major errors in both the MicroScan and disk diffusion test. Only 1 isolate was positive for carbapenemase screening test and all of the isolates were positive for AmpC screening test. In conclusion, the detection of ertapenem resistance in Enterobacteriaceae has limitations using routine testing such as an automated system or disk diffusion. Confirmation of results by an additional MIC test is recommended for accurate resistance results of ertapenem. PMID:25794901

  3. Growth kinetics of Salmonella enterica in Hajna tetrathionate broth, Rappaport broth and modified semisolid Rappaport agar

    PubMed Central

    FUJIHARA, Masatoshi; TABUCHI, Hiroyuki; UEGAKI, Kaho

    2015-01-01

    To determine the appropriate method for isolating Salmonella enterica, we compared the growth of S. enterica serovars using three selective enrichment media. S. enterica was more successfully isolated from artificially contaminated fecal samples after enrichment in Hajna tetrathionate broth or modified semisolid Rappaport agar than in Rappaport broth. Since most bacteria (other than motile S. enterica) do not migrate on modified semisolid Rappaport agar, the growth characteristics of S. enterica can be interpreted easily and quickly. Two S. enterica isolates did not migrate on modified semisolid Rappaport agar, but did grow in Hajna tetrathionate broth, which suggests that the combined use of these selective enrichment media is appropriate for isolating S. enterica. PMID:26498402

  4. Comparison of impedance cardiography and dye dilution method for measuring cardiac output

    PubMed Central

    Spiering, W; van Es, P N; de Leeuw, P W

    1998-01-01

    Objective—To assess the degree of agreement between impedance cardiography, using the NCCOM3-R7 device, and the gold standard—the dye dilution method—both under basal conditions and after stimulation of cardiac output.
Patients—35 paired measurements in five healthy male volunteers.
Interventions—To obtain higher levels of cardiac output, cardiac performance was stimulated with a dopamine infusion.
Results—In 35 paired measurements, the mean of all the impedance values was higher than that of the dye dilution values, at 10.2 v 7.4 l/min (p < 0.0001). The mean discrepancy between the two methods was 3.3 l/min, and the mean bias −2.9 l/min, with limits of agreement of −9.0 and 3.2 l/min. A change in cardiac output could not adequately be predicted by the NCCOM3-R7. In 20 of 25 measurements obtained during continuous intravenous dopamine infusions there was a rise in dye dilution cardiac output (range 0.2 to 5.9 l/min). Neither the magnitude nor the direction of the change in dye dilution values corresponded with the change measured by impedance cardiography. The mean discrepancy here between the two methods was 1.8 l/min, and the mean bias −0.8 l/min, with limits of agreement of −4.9 and 3.3 l/min.
Conclusions—In healthy volunteers, impedance cardiography with NCCOM3-R7 is inadequate for assessing cardiac output when compared with the dye dilution method.

 Keywords: cardiac output;  impedance cardiography;  dye dilution PMID:9659188

  5. New method to assess dilution of secretions for immunological and microbiological assays.

    PubMed Central

    Virolainen, A; Mäkelä, M J; Esko, E; Jero, J; Alfthan, G; Sundvall, J; Leinonen, M

    1993-01-01

    Accurate quantitation of pathogens and antibody concentrations in secretions has been difficult because of unpredictable dilution of secretion with th diluent at the time of sample collection. We added an inert substance, lithium chloride (LiCl), to the sample diluent and measured its concentration with an atomic absorption spectrometer before and after the specimen was added. LiCl, at a concentration of 2 mmol of Li per liter, has no negative effect on the survival of common respiratory pathogens or on the results of immunoassays. The method is applicable to any sample collecting in which dilution of the specimen is necessary. PMID:8388894

  6. Body composition among Sri Lankan infants by 18*O dilution method and the validity of anthropometric equations to predict body fat against 18*O dilution

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Body composition indicators provide a better guidance for growth and nutritional status of the infants. This study was designed to (1) measure the body composition of the Sri Lankan infants using a reference method, the 18*O dilution method; (2) calculate the body fat content of the infants using pu...

  7. Fermented broth in tyrosinase- and melanogenesis inhibition.

    PubMed

    Chan, Chin-Feng; Huang, Ching-Cheng; Lee, Ming-Yuan; Lin, Yung-Sheng

    2014-01-01

    Fermented broth has a long history of applications in the food, pharmaceutical and cosmetic industries. Recently, the use of fermented broth in skin care products is in ascendance. This review investigates the efficacy of fermented broth in inhibiting tyrosinase and melanogenesis. Possible active ingredients and hypopigmentation mechanisms of fermented broth are discussed, and potential applications of fermented broth in the cosmetic industry are also addressed. PMID:25255749

  8. Comparison of disc diffusion, Etest and broth microdilution for testing susceptibility of carbapenem-resistant P. aeruginosa to polymyxins

    PubMed Central

    van der Heijden, Inneke M; Levin, Anna S; De Pedri, Ewerton H; Fung, Liang; Rossi, Flavia; Duboc, Gisele; Barone, Antonio A; Costa, Silvia F

    2007-01-01

    Background Considering the increasing use of polymyxins to treat infections due to multidrug resistant Gram-negative in many countries, it is important to evaluate different susceptibility testing methods to this class of antibiotic. Methods Susceptibility of 109 carbapenem-resistant P. aeruginosa to polymyxins was tested comparing broth microdilution (reference method), disc diffusion, and Etest using the new interpretative breakpoints of Clinical and Laboratory Standards Institute. Results Twenty-nine percent of isolates belonged to endemic clone and thus, these strains were excluded of analysis. Among 78 strains evaluated, only one isolate was resistant to polymyxin B by the reference method (MIC: 8.0 μg/mL). Very major and major error rates of 1.2% and 11.5% were detected comparing polymyxin B disc diffusion with the broth microdilution (reference method). Agreement within 1 twofold dilution between Etest and the broth microdilution were 33% for polymyxin B and 79.5% for colistin. One major error and 48.7% minor errors were found comparing polymyxin B Etest with broth microdilution and only 6.4% minor errors with colistin. The concordance between Etest and the broth microdilution (reference method) was respectively 100% for colistin and 90% for polymyxin B. Conclusion Resistance to polymyxins seems to be rare among hospital carbapenem-resistant P. aeruginosa isolates over a six-year period. Our results showed, using the new CLSI criteria, that the disc diffusion susceptibility does not report major errors (false-resistant results) for colistin. On the other hand, showed a high frequency of minor errors and 1 very major error for polymyxin B. Etest presented better results for colistin than polymyxin B. Until these results are reproduced with a large number of polymyxins-resistant P. aeruginosa isolates, susceptibility to polymyxins should be confirmed by a reference method. PMID:17697363

  9. Assessing the Accuracy of the Tracer Dilution Method with Atmospheric Dispersion Modeling

    NASA Astrophysics Data System (ADS)

    Taylor, D.; Delkash, M.; Chow, F. K.; Imhoff, P. T.

    2015-12-01

    Landfill methane emissions are difficult to estimate due to limited observations and data uncertainty. The mobile tracer dilution method is a widely used and cost-effective approach for predicting landfill methane emissions. The method uses a tracer gas released on the surface of the landfill and measures the concentrations of both methane and the tracer gas downwind. Mobile measurements are conducted with a gas analyzer mounted on a vehicle to capture transects of both gas plumes. The idea behind the method is that if the measurements are performed far enough downwind, the methane plume from the large area source of the landfill and the tracer plume from a small number of point sources will be sufficiently well-mixed to behave similarly, and the ratio between the concentrations will be a good estimate of the ratio between the two emissions rates. The mobile tracer dilution method is sensitive to different factors of the setup such as placement of the tracer release locations and distance from the landfill to the downwind measurements, which have not been thoroughly examined. In this study, numerical modeling is used as an alternative to field measurements to study the sensitivity of the tracer dilution method and provide estimates of measurement accuracy. Using topography and wind conditions for an actual landfill, a landfill emissions rate is prescribed in the model and compared against the emissions rate predicted by application of the tracer dilution method. Two different methane emissions scenarios are simulated: homogeneous emissions over the entire surface of the landfill, and heterogeneous emissions with a hot spot containing 80% of the total emissions where the daily cover area is located. Numerical modeling of the tracer dilution method is a useful tool for evaluating the method without having the expense and labor commitment of multiple field campaigns. Factors tested include number of tracers, distance between tracers, distance from landfill to transect

  10. Overcoming matrix effects using the dilution approach in multiresidue methods for fruits and vegetables.

    PubMed

    Ferrer, Carmen; Lozano, Ana; Agüera, Ana; Girón, A Jiménez; Fernández-Alba, A R

    2011-10-21

    During recent years matrix effects in liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) have quickly become a major concern in food analysis. The phenomenon of ion suppression can lead to errors in the quantification of the analytes of interest, as well as can affect detection capability, precision, and accuracy of the method. Sample dilution is an easy and effective method to reduce interfering compounds, and so, to diminish matrix effects. In this work, matrix effects of 53 pesticides in three different matrices (orange, tomato and leek) were evaluated. Several dilutions of the matrix were tested in order to study the evolution of signal suppression. Dilution of the extracts led to a reduction of the signal suppression in most of the cases. A dilution factor of 15 demonstrated to be enough to eliminate most of the matrix effects, opening the possibility to perform quantification with solvent based standards in the majority of the cases. In those cases where signal suppression could not be reduced, a possible solution would be to use stable isotope-labelled internal standards for quantification of the problematic pesticides. PMID:21820661

  11. Determination of beryllium in ores and rocks by a dilution-fluorometric method with morin

    USGS Publications Warehouse

    May, R.; Grimaldi, F.S.

    1961-01-01

    Beryllium in concentrations as little as a few parts per million is determined fluorometrically with morin in low grade ores by a dilution method without separations. A high sensitivity is obtained by the adoption of instrumental and reaction conditions that give a satisfactory ratio of beryllium to blank fluorescence and at the same time minimize iron interference. Data on the behavior of 47 ions are given. The method is applied to ores containing bertrandite and beryl as the beryllium minerals.

  12. Pleural liquid clearance rate measured in awake sheep by the volume of dilution method

    SciTech Connect

    Broaddus, V.C.; Wiener-Kronish, J.P.; Berthiaume, Y.; Staub, N.C.

    1986-03-01

    The authors reported 24h clearance of mock pleural effusions measured terminally in sheep. To measure effusion volume at different times in the same sheep, they injected /sup 111/In-transferrin and measured its dilution. In 5 sheep with effusions of known sizes, the method was accurate to +/-10%. In 5 awake sheep, the authors injected 10 ml/kg of a 1% protein solution via a non-penetrating rib capsule. At 6h, the authors measured the volume by the dilution method and at 24h by direct recovery. The clearance rate in each animal was constant at 2.9-6.0%/h (average 4.8 +/- 1.3%/h). This new method gives a reliable two point clearance rate and requires fewer animals.

  13. Xanthan gum recovery from fermentation broth using ultrafiltration: Kinetics and process evaluation

    SciTech Connect

    Lo, Y.M.; Yang, S.T.; Min, D.B.

    1995-12-01

    Ultrafiltration of xanthan gum solution as an alternative method to alcohol precipitation for xanthan gum recovery from dilute fermentation broth was studied. A polysulfone membrane (with 500,000 MWCO) hollow fiber (106 mil fiber diameter) tubular cartridge was used to concentrate xanthan broth from less than 3 (w/v) % to {approximately}13.5 (w/v) %, with the xanthan recovery yield of {approximately}95 % or higher. During ultrafiltration, the filtrate flux was one order of magnitude lower for xanthan broth than for water, However, the flux remained almost constant for xanthan concentrations up to {approximately}8%. It was then reduced dramatically as the xanthan concentration increased beyond 8%. The reduced filtrate flux was caused by the reduced pumping (shear) rate and higher viscosities at higher xanthan concentrations. At constant xanthan concentration, the filtrate flux remained almost unchanged for the entire period studied, suggesting that the process is not subject to membrane fouling. In general, the filtrate flux decreased with increasing the xanthan concentration and increased with increasing the pumping (shear) rate and the trans-membrane pressure difference. Changing the solution pH had a slight effect on the viscosity of xanthan solution, but did not affect the filtration performance. Even under high-shear-rate conditions, ultrafiltration did not give any adverse effects on the rheological properties and molecular weight of the xanthan polymer. Thus, ultra filtration can be used to concentrate xanthan broth from fermentation by a factor of four or higher and to reduce the subsequent alcohol recovery costs by at least 75 %.

  14. Determination of Hydrogen Sulfide in Fermentation Broths Containing SO21

    PubMed Central

    Acree, T. E.; Sonoff, Elisabeth P.; Splittstoesser, D. F.

    1971-01-01

    A procedure for the determination of hydrogen sulfide in fermentation broths containing up to 100 μg of SO2 per ml is described. The method involves the sparging of H2S from the broth into a cadmium hydroxide absorption solution, the formation of methylene blue from the absorbed sulfide, and the measuring of this color spectrophotometrically. The use of cadmium hydroxide instead of zinc acetate, the common absorbent, substantially reduced the interference of SO2 with the analysis. PMID:5111300

  15. Isotopic Dilution GC/MS Method for Methionine Determination in Biological Media

    NASA Astrophysics Data System (ADS)

    Horj, Elena; Iordache, Andreea; Culea, Monica

    2011-10-01

    The isotopic dilution mass spectrometry technique is the method of choice for sensitive and accurate determination of analytes in biological samples. The aim of this work was to establish a sensitive analytical method for the determination of methionine in different biological media. Quantitation of methionine from the resultant tracer spectrum requires deconvolution of the enrichment of the isotopomers. Deconvolution of the ion abundance ratios to yield tracer-to-tracee ratio for the isotopomer was done using Brauman's least squares approach. Comparison with regression curve calculation method is presented. The method was applied for amino-acids determination in beef, pork and fish meat.

  16. Evaluation of the Boron Dilution Method for Moderator Temperature Coefficient Measurements

    SciTech Connect

    Demaziere, Christophe; Pazsit, Imre; Por, Gabor

    2002-11-15

    A measurement of the at-power moderator temperature coefficient (MTC) at the pressurized water reactor Unit 4 of the Ringhals Nuclear Power Plant (Sweden) during fuel cycle 16 is analyzed. The measurement was performed when the boron concentration decreased under 300 ppm in the reactor coolant system, by using the boron dilution method. Detailed calculations were made to estimate all reactivity effects taking place during such a measurement. These effects can only be accounted for through static core calculations that allow calculating contributions to the reactivity change induced by the moderator temperature change. All the calculations were performed with the Studsvik Scandpower SIMULATE-3 code. Analysis of the measurement showed that the contribution of the Doppler effect (in the fuel) was almost negligible, whereas the reactivity effects due to other than the Doppler fuel coefficient and the boron change were surprisingly significant. It was concluded that due to the experimental inaccuracies, the uncertainty associated with the boron dilution method could be much larger than previously expected. The MTC might then be close to -72 pcm/degC, whereas the main goal of the measurement is to verify that the MTC is larger (less negative) than this threshold. The usefulness of the boron dilution method for MTC measurements can therefore be questioned.

  17. Melanin bleaching with dilute hydrogen peroxide: a simple and rapid method.

    PubMed

    Liu, Chia-Hsing; Lin, Chih-Hung; Tsai, Min-Jan; Chen, Wan-Tzu; Chai, Chee-Yin; Huang, Ya-Chun; Tsai, Kun-Bow

    2013-05-01

    Melanins are naturally occurring pigments in both normal and pathologic tissues. Two common bleaching processes are potassium permanganate followed by oxalic acid treatment and dilute hydrogen peroxide (H2O2) process. The potassium permanganate/oxalic acid method is faster and more easily incorporated in conventional daily immunostaining protocols, whereas the dilute H2O2 method requires 24 hours. This study aimed to reduce melanin bleaching time by using a 10% H2O2 dilution. First, reaction time was reduced to 30 minutes by raising the temperature to 65°C. Second, containers with high thermal conductivity were used to improve bleaching effectiveness. Experimental comparisons of melanin treatments with H2O2 contained in an iron jar, a glass coplin jar, and a plastic steel jar obtained bleaching time of 20, 30, and 40 minutes, respectively. These modifications of the conventional bleaching method significantly improve the speed and efficiency of the procedure and are recommended when performing immunohistochemical studies. PMID:23060296

  18. Method of determining the optimal dilution ratio for fluorescence fingerprint of food constituents.

    PubMed

    Trivittayasil, Vipavee; Tsuta, Mizuki; Kokawa, Mito; Yoshimura, Masatoshi; Sugiyama, Junichi; Fujita, Kaori; Shibata, Mario

    2015-01-01

    Quantitative determination by fluorescence spectroscopy is possible because of the linear relationship between the intensity of emitted fluorescence and the fluorophore concentration. However, concentration quenching may cause the relationship to become nonlinear, and thus, the optimal dilution ratio has to be determined. In the case of fluorescence fingerprint (FF) measurement, fluorescence is measured under multiple wavelength conditions and a method of determining the optimal dilution ratio for multivariate data such as FFs has not been reported. In this study, the FFs of mixed solutions of tryptophan and epicatechin of different concentrations and composition ratios were measured. Principal component analysis was applied, and the resulting loading plots were found to contain useful information about each constituent. The optimal concentration ranges could be determined by identifying the linear region of the PC score plotted against total concentration. PMID:25485961

  19. Turbidity as a method of preparing sperm dilutions in the echinoid sperm/egg bioassay

    SciTech Connect

    Hall, T.J.; Haley, R.K.; Battan, K.J. )

    1993-11-01

    The use of turbidimeter for preparing sperm dilutions used in the echinoid sperm/egg bioassay was evaluated. Regression analyses of the relationship between sperm density and turbidity for the sea urchins Strongylocentrotus purpuratus and Strongylocentrotus droebachiensis and the sand dollar Dendraster excentricus indicated that although there were slope differences for each species, each coefficient of determination was highly significant. For Dendraster excentricus, triplicate hemacytometer counts over a range of turbidities as well as repeated preparations of a single sperm turbidity indicated similar variability for each. The use of the turbidimeter has time-saving advantages over conventional hemacytometer methods without sacrificing precision. Sperm dilutions can be prepared rapidly, minimizing seawater sperm preactivation before test initiation, and may therefore contribute to increased test precision.

  20. Lattice-Boltzmann method for the simulation of multiphase mass transfer and reaction of dilute species

    NASA Astrophysics Data System (ADS)

    Riaud, Antoine; Zhao, Shufang; Wang, Kai; Cheng, Yi; Luo, Guangsheng

    2014-05-01

    Despite the popularity of the lattice-Boltzmann method (LBM) in simulating multiphase flows, a general approach for modeling dilute species in multiphase systems is still missing. In this report we propose to modify the collision operator of the solute by introducing a modified redistribution scheme. This operator is based on local fluid variables and keeps the parallelism inherent to LBM. After deriving macroscopic transport equations, an analytical equation of state of the solute is exhibited and the method is proven constituting a unified framework to simulate arbitrary solute distribution between phases, including single-phase soluble compounds, amphiphilic species with a partition coefficient, and surface-adsorbed compounds.

  1. Lattice-Boltzmann method for the simulation of multiphase mass transfer and reaction of dilute species.

    PubMed

    Riaud, Antoine; Zhao, Shufang; Wang, Kai; Cheng, Yi; Luo, Guangsheng

    2014-05-01

    Despite the popularity of the lattice-Boltzmann method (LBM) in simulating multiphase flows, a general approach for modeling dilute species in multiphase systems is still missing. In this report we propose to modify the collision operator of the solute by introducing a modified redistribution scheme. This operator is based on local fluid variables and keeps the parallelism inherent to LBM. After deriving macroscopic transport equations, an analytical equation of state of the solute is exhibited and the method is proven constituting a unified framework to simulate arbitrary solute distribution between phases, including single-phase soluble compounds, amphiphilic species with a partition coefficient, and surface-adsorbed compounds. PMID:25353915

  2. Recovery of succinic acid from fermentation broth.

    PubMed

    Kurzrock, Tanja; Weuster-Botz, Dirk

    2010-03-01

    Succinic acid is of high interest as bio-feedstock for the chemical industry. It is a precursor for a variety of many other chemicals, e.g. 1,4-butandiol, tetrahydrofuran, biodegradable polymers and fumaric acid. Besides optimized production strains and fermentation processes it is indispensable to develop cost-saving and energy-effective downstream processes to compete with the current petrochemical production process. Various methods such as precipitation, sorption and ion exchange, electrodialysis, and liquid-liquid extraction have been investigated for the recovery of succinic acid from fermentation broth and are reviewed critically here. PMID:19898782

  3. Synthesis of nano-sized amorphous boron powders through active dilution self-propagating high-temperature synthesis method

    SciTech Connect

    Wang, Jilin; Gu, Yunle; Li, Zili; Wang, Weimin; Fu, Zhengyi

    2013-06-01

    Graphical abstract: Nano-sized amorphous boron powders were synthesized by active dilution self-propagating high-temperature synthesis (SHS) method. The effects of endothermic reaction rate, the possible chemical reaction mechanism and active dilution model for synthesis of the product were also discussed. Highlights: ► Nano-sized amorphous boron powders were synthesized by active dilution self-propagating high-temperature synthesis method. ► The morphology, particle size and purity of the samples could be effectively controlled via changing the endothermic rate. ► The diluter KBH{sub 4} played an important role in active dilution synthesis of amorphous nano-sized boron powders. ► The active dilution method could be further popularized and become a common approach to prepare various inorganic materials. - Abstract: Nano-sized amorphous boron powders were synthesized by active dilution self-propagating high-temperature synthesis (SHS) method at temperatures ranging from 700 °C to 850 °C in a SHS furnace using Mg, B{sub 2}O{sub 3} and KBH{sub 4} as raw materials. Samples were characterized by X-ray powder diffraction (XRD), Laser particle size analyzer, Fourier transform infrared spectra (FTIR), X-ray energy dispersive spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission TEM (HRTEM). The boron powders demonstrated an average particle size of 50 nm with a purity of 95.64 wt.%. The diluter KBH{sub 4} played an important role in the active dilution synthesis of amorphous nano-sized boron powders. The effects of endothermic reaction rate, the possible chemical reaction mechanism and active dilution model for synthesis of the product were also discussed.

  4. Ultra scale-down characterization of the impact of conditioning methods for harvested cell broths on clarification by continuous centrifugation-Recovery of domain antibodies from rec E. coli.

    PubMed

    Chatel, Alex; Kumpalume, Peter; Hoare, Mike

    2014-05-01

    The processing of harvested E. coli cell broths is examined where the expressed protein product has been released into the extracellular space. Pre-treatment methods such as freeze-thaw, flocculation, and homogenization are studied. The resultant suspensions are characterized in terms of the particle size distribution, sensitivity to shear stress, rheology and solids volume fraction, and, using ultra scale-down methods, the predicted ability to clarify the material using industrial scale continuous flow centrifugation. A key finding was the potential of flocculation methods both to aid the recovery of the particles and to cause the selective precipitation of soluble contaminants. While the flocculated material is severely affected by process shear stress, the impact on the very fine end of the size distribution is relatively minor and hence the predicted performance was only diminished to a small extent, for example, from 99.9% to 99.7% clarification compared with 95% for autolysate and 65% for homogenate at equivalent centrifugation conditions. The lumped properties as represented by ultra scale-down centrifugation results were correlated with the basic properties affecting sedimentation including particle size distribution, suspension viscosity, and solids volume fraction. Grade efficiency relationships were used to allow for the particle and flow dynamics affecting capture in the centrifuge. The size distribution below a critical diameter dependent on the broth pre-treatment type was shown to be the main determining factor affecting the clarification achieved. PMID:24284936

  5. A new tracer technique for monitoring groundwater fluxes: the Finite Volume Point Dilution Method.

    PubMed

    Brouyère, Serge; Batlle-Aguilar, Jordi; Goderniaux, Pascal; Dassargues, Alain

    2008-01-28

    Quantification of pollutant mass fluxes is essential for assessing the impact of contaminated sites on their surrounding environment, particularly on adjacent surface water bodies. In this context, it is essential to quantify but also to be able to monitor the variations with time of Darcy fluxes in relation with changes in hydrogeological conditions and groundwater - surface water interactions. A new tracer technique is proposed that generalizes the single-well point dilution method to the case of finite volumes of tracer fluid and water flush. It is called the Finite Volume Point Dilution Method (FVPDM). It is based on an analytical solution derived from a mathematical model proposed recently to accurately model tracer injection into a well. Using a non-dimensional formulation of the analytical solution, a sensitivity analysis is performed on the concentration evolution in the injection well, according to tracer injection conditions and well-aquifer interactions. Based on this analysis, optimised field techniques and interpretation methods are proposed. The new tracer technique is easier to implement in the field than the classical point dilution method while it further allows monitoring temporal changes of the magnitude of estimated Darcy fluxes, which is not the case for the former technique. The new technique was applied to two experimental sites with contrasting objectives, geological and hydrogeological conditions, and field equipment facilities. In both cases, field tracer concentrations monitored in the injection wells were used to fit the calculated modelled concentrations by adjusting the apparent Darcy flux crossing the well screens. Modelling results are very satisfactory and indicate that the methodology is efficient and accurate, with a wide range of potential applications in different environments and experimental conditions, including the monitoring with time of changes in Darcy fluxes. PMID:17949849

  6. Dilutions Made Easy.

    ERIC Educational Resources Information Center

    Kamin, Lawrence

    1996-01-01

    Presents problems appropriate for high school and college students that highlight dilution methods. Promotes an understanding of dilution methods in order to prevent the unnecessary waste of chemicals and glassware in biology laboratories. (JRH)

  7. Use of Isotope Dilution Method To Predict Bioavailability of Organic Pollutants in Historically Contaminated Sediments

    PubMed Central

    2015-01-01

    Many cases of severe environmental contamination arise from historical episodes, where recalcitrant contaminants have resided in the environment for a prolonged time, leading to potentially decreased bioavailability. Use of bioavailable concentrations over bulk chemical levels improves risk assessment and may play a critical role in determining the need for remediation or assessing the effectiveness of risk mitigation operations. In this study, we applied the principle of isotope dilution to quantify bioaccessibility of legacy contaminants DDT and PCBs in marine sediments from a Superfund site. After addition of 13C or deuterated analogues to a sediment sample, the isotope dilution reached a steady state within 24 h of mixing. At the steady state, the accessible fraction (E) derived by the isotope dilution method (IDM) ranged from 0.28 to 0.89 and was substantially smaller than 1 for most compounds, indicating reduced availability of the extensively aged residues. A strong linear relationship (R2 = 0.86) was found between E and the sum of rapid (Fr) and slow (Fs) desorption fractions determined by sequential Tenax desorption. The IDM-derived accessible concentration (Ce) was further shown to correlate closely with tissue residue in the marine benthic polychaete Neanthes arenaceodentata exposed in the same sediments. As shown in this study, the IDM approach involves only a few simple steps and may be readily adopted in laboratories equipped with mass spectrometers. This novel method is expected to be especially useful for historically contaminated sediments or soils, for which contaminant bioavailability may have changed significantly due to aging and other sequestration processes. PMID:24946234

  8. Use of isotope dilution method to predict bioavailability of organic pollutants in historically contaminated sediments.

    PubMed

    Jia, Fang; Bao, Lian-Jun; Crago, Jordan; Schlenk, Daniel; Gan, Jay

    2014-07-15

    Many cases of severe environmental contamination arise from historical episodes, where recalcitrant contaminants have resided in the environment for a prolonged time, leading to potentially decreased bioavailability. Use of bioavailable concentrations over bulk chemical levels improves risk assessment and may play a critical role in determining the need for remediation or assessing the effectiveness of risk mitigation operations. In this study, we applied the principle of isotope dilution to quantify bioaccessibility of legacy contaminants DDT and PCBs in marine sediments from a Superfund site. After addition of 13C or deuterated analogues to a sediment sample, the isotope dilution reached a steady state within 24 h of mixing. At the steady state, the accessible fraction (E) derived by the isotope dilution method (IDM) ranged from 0.28 to 0.89 and was substantially smaller than 1 for most compounds, indicating reduced availability of the extensively aged residues. A strong linear relationship (R2=0.86) was found between E and the sum of rapid (Fr) and slow (Fs) desorption fractions determined by sequential Tenax desorption. The IDM-derived accessible concentration (Ce) was further shown to correlate closely with tissue residue in the marine benthic polychaete Neanthes arenaceodentata exposed in the same sediments. As shown in this study, the IDM approach involves only a few simple steps and may be readily adopted in laboratories equipped with mass spectrometers. This novel method is expected to be especially useful for historically contaminated sediments or soils, for which contaminant bioavailability may have changed significantly due to aging and other sequestration processes. PMID:24946234

  9. An isotope-dilution standard GC/MS/MS method for steroid hormones in water

    USGS Publications Warehouse

    Foreman, William T.; Gray, James L.; ReVello, Rhiannon C.; Lindley, Chris E.; Losche, Scott A.

    2013-01-01

    An isotope-dilution quantification method was developed for 20 natural and synthetic steroid hormones and additional compounds in filtered and unfiltered water. Deuterium- or carbon-13-labeled isotope-dilution standards (IDSs) are added to the water sample, which is passed through an octadecylsilyl solid-phase extraction (SPE) disk. Following extract cleanup using Florisil SPE, method compounds are converted to trimethylsilyl derivatives and analyzed by gas chromatography with tandem mass spectrometry. Validation matrices included reagent water, wastewater-affected surface water, and primary (no biological treatment) and secondary wastewater effluent. Overall method recovery for all analytes in these matrices averaged 100%; with overall relative standard deviation of 28%. Mean recoveries of the 20 individual analytes for spiked reagent-water samples prepared along with field samples analyzed in 2009–2010 ranged from 84–104%, with relative standard deviations of 6–36%. Detection levels estimated using ASTM International’s D6091–07 procedure range from 0.4 to 4 ng/L for 17 analytes. Higher censoring levels of 100 ng/L for bisphenol A and 200 ng/L for cholesterol and 3-beta-coprostanol are used to prevent bias and false positives associated with the presence of these analytes in blanks. Absolute method recoveries of the IDSs provide sample-specific performance information and guide data reporting. Careful selection of labeled compounds for use as IDSs is important because both inexact IDS-analyte matches and deuterium label loss affect an IDS’s ability to emulate analyte performance. Six IDS compounds initially tested and applied in this method exhibited deuterium loss and are not used in the final method.

  10. Atmospheric dispersion modeling to assess the tracer dilution method for measuring landfill methane emissions

    NASA Astrophysics Data System (ADS)

    Taylor, D.; Delkash, M.; Chow, F. K.; Imhoff, P. T.

    2014-12-01

    Landfill methane emissions are difficult to estimate due to limited observation and uncertainty of the data. The tracer dilution method is a widely used approach that uses a tracer gas released at a known rate from one or more point sources, and the ratio of the concentration of tracer gas to concentration of methane measured at a downwind point is used to calculate the methane emissions rate. Here we use a high-resolution atmospheric model to examine the set-up of the tracer dilution method and its effects on the accuracy of methane emissions calculations. This method relies on optimal weather conditions and is limited by availability of locations where downwind measurements can be taken. Therefore using limited measurements taken with this method to estimate annual landfill emissions will yield totals of dubious accuracy. The Weather Research and Forecasting model (WRF) is a mesoscale meteorological model that is commonly used for atmospheric research as well as operational forecasts. Here, a scalar tracking subroutine is added to WRF to simulate the methane emissions from the surface of the landfill and the tracer gas from point sources. Using this model, many different tracer release configurations (number and placement of tracer release points and downwind measurement locations) are simulated and compared. Wind speed dependence of methane emissions is examined by prescribing surface flux as a function of local wind speed. The tracer dilution method can only collect landfill emissions data during ideal weather conditions, so modeling emissions during non-ideal conditions will give a better idea of how to predict total annual emissions taking into account the emissions on days when emissions cannot accurately be measured. The WRF output is compared to output of an analogous model adapted from the existing atmospheric model Advanced Regional Prediction System (ARPS) and to observation data from Sandtown Landfill in Delaware, USA. Future work includes adding

  11. A stable isotope dilution method for measuring bioavailability of organic contaminants

    PubMed Central

    Delgado-Moreno, Laura; Gan, Jay

    2014-01-01

    Methods for determining bioavailability of organic contaminants suffer various operational limitations. We explored the use of stable isotope labeled references in developing an isotope dilution method (IDM) to measure the exchangeable pool (E) of pyrene and bifenthrin as an approximation of their bioavailability in sediments. The exchange of deuterated bifenthrin or pyrene with its native counterpart was completed within 48 h. The derived E was 38–82% for pyrene and 28–59% for bifenthrin. Regression between E and the sum of rapid and slow desorption fractions obtained from sequential desorption showed a slope close to 1.0. The ability of IDM to predict bioavailability was further shown from a strong relationship (r2 > 0.93) between E and bioaccumulation into Chironomus tentans. Given the abundance of stable isotope labeled references and their relatively easy analysis, the IDM has the potential to become a readily adoptable tool for estimating organic contaminants bioaccessibility in various matrices. PMID:23434573

  12. Fast extraction and dilution flow injection mass spectrometry method for quantitative chemical residue screening in food.

    PubMed

    Nanita, Sergio C; Stry, James J; Pentz, Anne M; McClory, Joseph P; May, John H

    2011-07-27

    A prototype multiresidue method based on fast extraction and dilution of samples followed by flow injection mass spectrometric analysis is proposed here for high-throughput chemical screening in complex matrices. The method was tested for sulfonylurea herbicides (triflusulfuron methyl, azimsulfuron, chlorimuron ethyl, sulfometuron methyl, chlorsulfuron, and flupyrsulfuron methyl), carbamate insecticides (oxamyl and methomyl), pyrimidine carboxylic acid herbicides (aminocyclopyrachlor and aminocyclopyrachlor methyl), and anthranilic diamide insecticides (chlorantraniliprole and cyantraniliprole). Lemon and pecan were used as representative high-water and low-water content matrices, respectively, and a sample extraction procedure was designed for each commodity type. Matrix-matched external standards were used for calibration, yielding linear responses with correlation coefficients (r) consistently >0.99. The limits of detection (LOD) were estimated to be between 0.01 and 0.03 mg/kg for all analytes, allowing execution of recovery tests with samples fortified at ≥0.05 mg/kg. Average analyte recoveries obtained during method validation for lemon and pecan ranged from 75 to 118% with standard deviations between 3 and 21%. Representative food processed fractions were also tested, that is, soybean oil and corn meal, yielding individual analyte average recoveries ranging from 62 to 114% with standard deviations between 4 and 18%. An intralaboratory blind test was also performed; the method excelled with 0 false positives and 0 false negatives in 240 residue measurements (20 samples × 12 analytes). The daily throughput of the fast extraction and dilution (FED) procedure is estimated at 72 samples/chemist, whereas the flow injection mass spectrometry (FI-MS) throughput could be as high as 4.3 sample injections/min, making very efficient use of mass spectrometers with negligible instrumental analysis time compared to the sample homogenization, preparation, and data

  13. Ultra Scale-Down Characterization of the Impact of Conditioning Methods for Harvested Cell Broths on Clarification by Continuous Centrifugation—Recovery of Domain Antibodies from rec E. coli

    PubMed Central

    Chatel, Alex; Kumpalume, Peter; Hoare, Mike

    2014-01-01

    The processing of harvested E. coli cell broths is examined where the expressed protein product has been released into the extracellular space. Pre-treatment methods such as freeze–thaw, flocculation, and homogenization are studied. The resultant suspensions are characterized in terms of the particle size distribution, sensitivity to shear stress, rheology and solids volume fraction, and, using ultra scale-down methods, the predicted ability to clarify the material using industrial scale continuous flow centrifugation. A key finding was the potential of flocculation methods both to aid the recovery of the particles and to cause the selective precipitation of soluble contaminants. While the flocculated material is severely affected by process shear stress, the impact on the very fine end of the size distribution is relatively minor and hence the predicted performance was only diminished to a small extent, for example, from 99.9% to 99.7% clarification compared with 95% for autolysate and 65% for homogenate at equivalent centrifugation conditions. The lumped properties as represented by ultra scale-down centrifugation results were correlated with the basic properties affecting sedimentation including particle size distribution, suspension viscosity, and solids volume fraction. Grade efficiency relationships were used to allow for the particle and flow dynamics affecting capture in the centrifuge. The size distribution below a critical diameter dependant on the broth pre-treatment type was shown to be the main determining factor affecting the clarification achieved. Biotechnol. Bioeng. 2014;111: 913–924. © 2013 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc. PMID:24284936

  14. Precision of a field method for determination of pH in dilute lakes

    USGS Publications Warehouse

    Turk, J.T.

    1986-01-01

    Replicate pH measurements in three dilute lakes made during extreme conditions indicate that pH can be measured in the field with a variance due to measurement error of 0.005 unit. Error of the field technique in measuring the pH of dilute solutions in the laboratory ranges from less than 0.01 unit in dilute strong-acid solutions to about 0.05 unit in air-saturated deionized water.

  15. Comparison of the Sensititre YeastOne® dilution method with the Clinical Laboratory Standards Institute (CLSI) M27-A3 microbroth dilution reference method for determining MIC of eight antifungal agents on 102 yeast strains.

    PubMed

    Bertout, S; Dunyach, C; Drakulovski, P; Reynes, J; Mallié, M

    2011-02-01

    The Clinical Laboratory Standards Institute ([CLSI] formerly NCCLS) reference broth microdilution testing method (protocol M27-A3) was compared with a commercially available methods (Sensititre YeastOne(®)) by testing two quality control strains and 102 isolates of Candida sp. and Cryptococcus sp. against fluconazole, itraconazole, ketoconazole, posaconazole, voriconazole, flucytosin, amphotericin B and caspofungin. Minimal inhibitory concentrations (MIC) endpoints were determined after 24h of incubation for Sensititre YeastOne(®) and after 24 and 48 h for CLSI microdilution method. Essential agreements between methods vary from 70.6 to 92.2%. Categorical agreements vary from 94.1% for 5FC to 72.6% for AMB. Sensititre YeastOne(®) reading appears to be useful for avoiding very major errors and this confirms the interest of this method for evaluating new antifungals activity in vitro. PMID:20843616

  16. Method of phase space beam dilution utilizing bounded chaos generated by rf phase modulation

    NASA Astrophysics Data System (ADS)

    Pham, Alfonse N.; Lee, S. Y.; Ng, K. Y.

    2015-12-01

    This paper explores the physics of chaos in a localized phase-space region produced by rf phase modulation applied to a double rf system. The study can be exploited to produce rapid particle bunch broadening exhibiting longitudinal particle distribution uniformity. Hamiltonian models and particle-tracking simulations are introduced to understand the mechanism and applicability of controlled particle diffusion. When phase modulation is applied to the double rf system, regions of localized chaos are produced through the disruption and overlapping of parametric resonant islands and configured to be bounded by well-behaved invariant tori to prevent particle loss. The condition of chaoticity and the degree of particle dilution can be controlled by the rf parameters. The method has applications in alleviating adverse space-charge effects in high-intensity beams, particle bunch distribution uniformization, and industrial radiation-effects experiments.

  17. Processing ethanol fermentation broths and stillage with ceramic membranes

    SciTech Connect

    Cheryan, M.

    1994-12-31

    The manufacture of ethanol from biomass requires several separation operations, many of which can benefit by the appropriate membrane technology. This paper discusses applications which may perhaps be done best with inorganic membranes. After the fermentation, the microbial (e.g., yeast) are usually separated from the fermentation broth and may be recycled for fermentation. The ethanol is stripped away from the fermentation broth by steam, leaving behind the {open_quotes}stillage{close_quotes}. This stillage is then separated into a high-solids fraction and a {open_quotes}thin{close_quotes} stillage; the latter forming as much as 60-80% of the total liquid throughput in an ethanol plant, could be stream to conserve water. Traditional separation methods used today include sedimentation, centrifugation and cake filtration. The authors have been studying the application of ceramic membranes for the separation (and possible recycling) of yeast (Saccharomyces cerevisiae) in ethanol fermentation broths, and for the clarification of thin stillage.

  18. Development of large area nanostructured silicon-hydrogen alloy material with improved stability for solar cell application by argon dilution method

    NASA Astrophysics Data System (ADS)

    Dey, Arka; Das, Mrinmay; Datta, Joydeep; Jana, Rajkumar; Dhar, Joydeep; Sil, Sayantan; Biswas, Debasish; Banerjee, Chandan; Ray, Partha Pratim

    2016-07-01

    Here we have presented the results of large area (30 × 30 cm2) silicon-hydrogen alloy material and solar cell by argon dilution method. As an alternative to hydrogen dilution, argon dilution method has been applied to develop single junction solar cell with appreciable stability. Optimization of deposition conditions revealed that 95% argon dilution gives a nanostructured material with improved transport property and less light induced degradation. The minority carrier diffusion length (L d ) and mobility-lifetime (μτ) product of the material with 95% argon dilution degrades least after light soaking. Also the density of states (DOS) below conduction level reveals that this material is less defective. Solar cell with this argon diluted material has been fabricated with all the layers deposited by argon dilution method. Finally we have compared the argon diluted solar cell results with the optimized hydrogen diluted solar cell. Light soaking study proves that it is possible to develop stable solar cell on large area by argon dilution method and that the degradation of argon diluted solar cell is less than that of hydrogen diluted one. [Figure not available: see fulltext.

  19. Multi-mycotoxin stable isotope dilution LC-MS/MS method for Fusarium toxins in cereals.

    PubMed

    Habler, Katharina; Rychlik, Michael

    2016-01-01

    A multi-mycotoxin stable isotope dilution LC-MS/MS method was developed for 14 Fusarium toxins including modified mycotoxins in cereals (deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, HT2-toxin, T2-toxin, enniatin B, enniatin B1, enniatin A1, enniatin A, beauvericin, fusarenone X, nivalenol, deoxynivalenol-3-glucoside, and zearalenone). The chromatographic separation of the toxins with particular focus on deoxynivalenol and deoxynivalenol-3-glucoside was achieved using a C18-hydrosphere column. An expedient sample preparation method was developed that uses solid-phase extraction for the purification of trichothecenes combined with zearalenone, enniatins, and beauvericin and provides excellent validation data. Linearity, intra-day precision, inter-day precision, and recoveries were ≥0.9982, 1-6%, 5-12%, and 79-117%, respectively. Method accuracy was verified by analyzing certified reference materials for deoxynivalenol, HT2-toxin, and T2-toxin with deviations below 7%. The results of this method found barley malt samples from 2012, 2013, and 2014 frequently contaminated with high concentrations of enniatin B, deoxynivalenol, and its modified mycotoxin deoxynivalenol-3-glucoside. Samples from 2012 were especially contaminated. Fusarenone X was not detected in any of the analyzed samples. PMID:26514672

  20. Screening fungicides for use in fish culture: Evaluation of the agar plug transfer, cellophane transfer, and agar dilution methods

    USGS Publications Warehouse

    Bailey, Tom A.

    1983-01-01

    The reliability, reproducibility, and usefulness of three screening methods -- the cellophane transfer, the agar plug transfer, and the agar dilution -- to screen aquatic fungicides were evaluated. Achlya flagellata and Saprolegnia hypogyna were exposed to 1, 10, and 100 mg/L of malachite green to test each method. The cellophane transfer and agar plug transfer techniques had similar reliability and reproducibility in rating fungicidal activity, and were both superior to the agar dilution technique. The agar plug transfer and agar dilution techniques adequately projected in vivo activity of malachite green, but the cellophane transfer technique overestimated its activity. Overall, the agar plug transfer technique most accurately rated the activity of malachite green and was the easiest test to perform. It therefore appears to be the method of choice for testing aquatic fungicides.

  1. 'Dilute-and-shoot' triple parallel mass spectrometry method for analysis of vitamin D and triacylglycerols in dietary supplements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A method is demonstrated for analysis of vitamin D-fortified dietary supplements that eliminates virtually all chemical pretreatment prior to analysis, and is referred to as a ‘dilute and shoot’ method. Three mass spectrometers, in parallel, plus a UV detector, an evaporative light scattering detec...

  2. Stable isotope dilution method for the determination of guanidinoacetic acid by gas chromatography/mass spectrometry.

    PubMed

    Fingerhut, Ralph

    2003-01-01

    For more than 30 years, guanidinoacetic acid (GAA), together with other guanidino compounds, has been proposed as an important marker for renal failure, in kidney transplantation, and for renal metabolism, especially for the metabolic activity of the renal proximal tubules. Since the discovery of the first patient with guanidinoacetic acid methyltransferase deficiency in 1994 by Stöckler et al. (Pediatr. Res. 1994; 36: 409), GAA has become of great interest for all laboratories involved in the diagnosis of metabolic diseases. In the literature there are several methods described for the determination of GAA, ranging from ion-exchange chromatography with post-column derivatisation, enzymatic methods, gas chromatography/mass spectrometry (GC/MS), to liquid chromatography/atmospheric pressure chemical ionisation mass spectrometry (LC/APCI-MS). Here a stable isotope dilution method for quantitative and accurate determination of GAA in urine, plasma, and cerebrospinal fluid is described. GAA is converted to the bis(trifluoromethyl)pyrimidine di(tert-butyldimethylsilyl) derivative by stepwise derivatisation with hexafluoroacetylacetone and N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide (MTBSTFA). Analysis can be performed using a standard benchtop GC/MS system. For quantitative GAA determination with 1,2-(13)C-GAA as internal standard, selected ion monitoring is performed using m/z 460/462, with m/z 432/433 and 375/376 as qualifiers. PMID:12661026

  3. A novel method for the quantification of quinic acid in food using stable isotope dilution analysis.

    PubMed

    Erk, Thomas; Bergmann, Hannah; Richling, Elke

    2009-01-01

    Organic acids play an important role in the flavor and taste of plant-derived foods. Quinic acid (QA) is one of the major acids. In the past, several methods like HPLC/UV, GC, and capillary electrophoresis were used for identification and quantification of QA. For the first time, a novel, sensitive, and selective method for the quantification of QA in food using stable isotope dilution analysis with HPLC/MS/MS has been established. Uniformly labeled 13C-QA was used as a standard to reduce sample preparations and to overcome matrix and ionization effects. The method was used to determine the QA content of red wines, instant coffees, and cloudy apple juices. QA contents of instant coffees were 64.4 and 63.6 g/kg powder. The concentrations in red wines were 24.0 and 25.1 mg/L, and 1493.3 and 1705.2 mg/L in cloudy apple juices. PMID:19610361

  4. Inaccuracy of the Disk Diffusion Method Compared with the Agar Dilution Method for Susceptibility Testing of Campylobacter spp.

    PubMed Central

    Kotilainen, Pirkko; Puukka, Pauli; Nakari, Ulla-Maija; Siitonen, Anja; Eerola, Erkki; Huovinen, Pentti; Hakanen, Antti J.

    2012-01-01

    The agar dilution method has been standardized by the CLSI for the susceptibility testing of Campylobacter species, and according to these standards, the disk diffusion method should be used only in screening for macrolide and ciprofloxacin resistance. Nevertheless, the disk diffusion test is currently widely used, since it is easy to perform in clinical microbiology laboratories. In this study, the disk diffusion method was compared to the agar dilution method by analyzing the in vitro activities of seven antimicrobial agents against 174 Campylobacter strains collected in Finland between 2003 and 2008. Recommendations of the CLSI were followed using Mueller-Hinton agar plates with 5% of sheep blood. For each strain, the disk diffusion tests were performed two to four times. Of the 33 erythromycin-resistant strains (MIC, ≥16 μg/ml), 24 (73%) constantly showed a 6-mm erythromycin inhibition zone (i.e., no inhibition), while for seven strains the inhibition zone varied from 6 to 44 mm in repeated measurements. Among the 141 erythromycin-susceptible strains (MIC, <16 μg/ml), erythromycin inhibition zones varied between 6 and 61 mm. Of the 87 ciprofloxacin-resistant strains, 47 (54%) showed 6-mm inhibition zones, while 40 strains showed inhibition zones between 6 and 60 mm. Significant differences between the repetitions were observed in the disk diffusion for all antimicrobial agents and all strains except for the macrolide-resistant strains regarding the macrolides. For 17 (10%) strains, the variation in repeated measurements was substantial. These results show that the disk diffusion method may not be a reliable tool for the susceptibility testing of Campylobacter spp. Further studies are needed to assess whether the disk diffusion test could be improved or whether all susceptibilities of campylobacters should be tested using an MIC-based method. PMID:22075583

  5. Prediction of infinite dilution benzene solubility in linear polyethylene melts via the direct particle deletion method.

    PubMed

    De Angelis, Maria Grazia; Boulougouris, Georgios C; Theodorou, Doros N

    2010-05-20

    The solubility of benzene in linear polyethylene melts was estimated via Monte Carlo simulations using a united-atom molecular model at temperatures between 373 and 573 K, in the infinite dilution limit. The excess chemical potential of the solute was evaluated with the direct particle deletion (DPD) method, whose rigorous derivation is presented here in detail: in this scheme, the benzene molecule united atoms are converted to hard spheres and then removed from the polymer system. The simulations were carried out in the N(1)N(2)PT ensemble using advanced Monte Carlo moves to equilibrate the polymeric phase. The evaluation of the accessible volume fraction for the "hard sphere" solute molecule required by the DPD method was performed analytically. The effect of the value of the arbitrary hard sphere diameter, d, on the computed thermodynamic quantities was determined, allowing us to establish an optimal range for the system considered. The values of Henry's law constant are in good agreement with experimental data from the literature in the temperature range considered and are comparable to those obtained with the lattice fluid and PC(SAFT) equations of state for the same system. PMID:20426442

  6. Solubility control in dilute magnetic semiconductors by using the co-doping method

    NASA Astrophysics Data System (ADS)

    Sato, Kazunori; Fujii, Hitoshi; Bergqvist, Lars; Dederichs, Peter H.; Katayama-Yoshida, Hiroshi

    2009-03-01

    To overcome low solubility limit of magnetic impurities in dilute magnetic semiconductors (DMS) and realize room temperature ferromagnetism, we propose a co-doping method to increase solubility of magnetic impurities in DMS [1]. We calculate electronic structure of (Ga, Mn)As, (Ga, Mn)N, (Ga, Cr)N and (Zn, Cr)Te with interstitial impurities, such as Li, Na and Cu, from first-principles by using the Korringa-Kohn- Rostoker coherent potential approximation (KKR-CPA) method. From the total energy results, it is shown that the mixing energy of magnetic impurity becomes negative and the solubility of magnetic impurities is strongly enhanced under the existence of interstitials [1]. In general, the co-dopants compensate hole carriers, thus the system becomes paramagnetic. However, owing to the large diffusivity of these interstitial impurities, we can anneal out the co-dopants after the crystal growth to recover the ferromagnetism. As an example, kinetic Monte Carlo simulations for the diffusion of interstitial co-dopants in DMS will be shown. [1] K. Sato et al., Jpn. J. Appl. Phys. 46 L1120 (2007)

  7. Comparison of Etest, disk diffusion, and broth macrodilution for in vitro susceptibility testing of Rhodococcus equi.

    PubMed

    Berghaus, Londa J; Giguère, Steeve; Guldbech, Kristen; Warner, Eleanor; Ugorji, Ukachi; Berghaus, Roy D

    2015-01-01

    MICs of erythromycin, clarithromycin, azithromycin, rifampin, gentamicin, and doxycycline against 101 isolates of Rhodococcus equi were determined by broth macrodilution, disk diffusion, and Etest. Categorical agreement ranged between 85.1 and 100%. Overall, the agreement between Etest and disk diffusion was better than the agreement between broth macrodilution and the agar-based methods. PMID:25378571

  8. Comparison of Etest, Disk Diffusion, and Broth Macrodilution for In Vitro Susceptibility Testing of Rhodococcus equi

    PubMed Central

    Berghaus, Londa J.; Guldbech, Kristen; Warner, Eleanor; Ugorji, Ukachi; Berghaus, Roy D.

    2014-01-01

    MICs of erythromycin, clarithromycin, azithromycin, rifampin, gentamicin, and doxycycline against 101 isolates of Rhodococcus equi were determined by broth macrodilution, disk diffusion, and Etest. Categorical agreement ranged between 85.1 and 100%. Overall, the agreement between Etest and disk diffusion was better than the agreement between broth macrodilution and the agar-based methods. PMID:25378571

  9. Quantification of methane and nitrous oxide emissions from various waste treatment facilities by tracer dilution method

    NASA Astrophysics Data System (ADS)

    Mønster, Jacob; Rella, Chris; Jacobson, Gloria; Kjeldsen, Peter; Scheutz, Charlotte

    2013-04-01

    Urban activities generate solid and liquid waste, and the handling and aftercare of the waste results in the emission of various compounds into the surrounding environment. Some of these compounds are emitted as gasses into the atmosphere, including methane and nitrous oxide. Methane and nitrous oxide are strong greenhouse gases and are considered to have 25 and 298 times the greenhouse gas potential of carbon dioxide on a hundred years term (Solomon et al. 2007). Global observations of both gasses have shown increasing concentrations that significantly contribute to the greenhouse gas effect. Methane and nitrous oxide are emitted from both natural and anthropogenic sources and inventories of source specific fugitive emissions from the anthropogenic sources of methane and nitrous oxide of are often estimated on the basis of modeling and mass balance. Though these methods are well-developed, actual measurements for quantification of the emissions is a very useful tool for verifying the modeling and mass balance as well as for validation initiatives done for lowering the emissions of methane and nitrous oxide. One approach to performing such measurements is the tracer dilution method (Galle et al. 2001, Scheutz et al. 2011), where the exact location of the source is located and a tracer gas is released at this source location at a known flow. The ratio of downwind concentrations of the tracer gas and the methane and nitrous oxide gives the emissions rates of the greenhouse gases. This tracer dilution method can be performed using both stationary and mobile measurements and in both cases, real-time measurements of both tracer and quantified gas are required, placing high demands on the analytical detection method. To perform the methane and nitrous oxide measurements, two robust instruments capable of real-time measurements were used, based on cavity ring-down spectroscopy and operating in the near-infrared spectral region. One instrument measured the methane and

  10. Separation of biopolymer from fermentation broths

    SciTech Connect

    Griffith, W.L.; Compere, A.L.; Westmoreland, C.G.; Johnson, J.S. Jr.

    1981-01-01

    Application of recent developments in filtration separations have been applied to separation of biopolymers from fermentation broths. More economical production of biopolymers near the site of use would be especially attractive for use in micellar flood programs for enhanced oil recovery. Solutions of the organisms Sclerotium rolfsii producing scleroglucans were used for the tests because the organisms are genetically more stable than the organisms that produce xanthan gums and because their more acid broths are less apt to become contaminated. Three types of filtration, axial filtration, pleated ultrafiltration module, and microscreens were tested on the broth. Filtration results are reported for broths with various preparation histories. An economic comparison is presented for processing of a ton of biopolymer per day, and the microscreening process is shown to be the most efficient, but a polishing step would have to be added. (BLM)

  11. Susceptibilities of genital mycoplasmas to the newer quinolones as determined by the agar dilution method.

    PubMed Central

    Kenny, G E; Hooton, T M; Roberts, M C; Cartwright, F D; Hoyt, J

    1989-01-01

    The increasing resistance of genital mycoplasmas to tetracycline poses a problem because tetracycline is one of the few antimicrobial agents active against Mycoplasma hominis, Ureaplasma urealyticum, chlamydiae, gonococci, and other agents of genitourinary-tract disease. Since the quinolones are a promising group of antimicrobial agents, the susceptibilities of M. hominis and U. urealyticum to the newer 6-fluoroquinolones were determined by the agar dilution method. Ciprofloxacin, difloxacin, and ofloxacin had good activity against M. hominis, with the MIC for 50% of isolates tested (MIC50) being 1 microgram/ml. Fleroxacin, lomefloxacin, pefloxacin, and rosoxacin had MIC50s of 2 micrograms/ml. Enoxacin, norfloxacin, and amifloxacin had MIC50s of 8 to 16 micrograms/ml, and cinoxacin and nalidixic acid were inactive (MIC50, greater than or equal to 256 micrograms/ml). Overall, the activities of 6-fluoroquinolones for ureaplasmas were similar to those for M. hominis, with MICs being the same or twofold greater. The most active 6-fluoroquinolones against ureaplasmas were difloxacin, ofloxacin, and pefloxacin, with MIC50s of 1 to 2 micrograms/ml. Ciprofloxacin was unusual in that the MIC50 for M. hominis was 1 microgram/ml, whereas the MIC50 for ureaplasmas was 8 micrograms/ml. Since the MIC50s for the most active quinolones approximate achievable concentrations in blood and urine, quinolones have promise in treating mycoplasmal infections. PMID:2712541

  12. A new method to determine the yield stress of diluted polymeric solutions

    NASA Astrophysics Data System (ADS)

    Soto, Enrique; Ruiz, Servando; Cordova Aguilar, Maria Soledad

    2012-11-01

    A new method to measure the yield stress for diluted polymeric solutions is presented. The tested solutions exhibit shear thinning behavior a once the critical yield stress is overcame. In rheology, these fluids are known as Herschel-Buckley. The yield stress phenomenon and its relation with bubble motion is an important issue for different industries, for example, personal care, paints and some others. As a result of the yield stress, small bubbles remain trapped in the fluid bulk, but above a critical volume, which is related with the characteristic yield stress, the bubbles flow in the liquid. In order to change the bubble volume, the liquid is placed in a cylindrical container whose pressure is decreased by a vacuum pump. The bubble growths as the pressure decreases and keeps its position until it reaches the critical volume. The bubble shape changes with volume and velocity, and a competition among surface, gravitational, inertial and viscous forces is discussed. The yield stress determined value is higher than the obtained from simple shear measurements due to the complex flow around the bubble.

  13. Shear viscosity of dilute suspensions of ellipsoidal particles with a lattice Boltzmann method

    NASA Astrophysics Data System (ADS)

    Huang, Haibo; Wu, YanFeng; Lu, Xiyun

    2012-10-01

    The intrinsic viscosities for prolate and oblate spheroidal suspensions in a dilute Newtonian fluid are studied using a three-dimensional lattice Boltzmann method. Through directly calculated viscous dissipation, the minimum and maximum intrinsic viscosities and the period of the tumbling state all agree well with the analytical solution for particles with different aspect ratios. This numerical test verifies the analysis on maximum and minimum intrinsic viscosities. Different behavior patterns of transient intrinsic viscosity in a period are analyzed in detail. A phase lag between the transient intrinsic viscosity and the orientation of the particle at finite Reynolds number (Re) is found and attributed to fluid and particle inertia. At lower Re, the phase lag increases with Re. There exists a critical Reynolds number Rea at which the phase lag begins to decrease with Re. The Rea depends on the aspect ratio of the particle. We found that both the intrinsic viscosity and the period change linearly with Re when ReRea (high-Re regime). In the high-Re regime, the dependence of the period on Re is consistent with a scaling law, and the dependence of the intrinsic viscosity on Re is well described by second-degree polynomial fits.

  14. Comparison of the radioisotope dilution-coated charcoal method and a microbiological method (L. leichmannii) for measuring vitamin B12 in serum

    PubMed Central

    Raven, J. L.; Walker, P. L.; Barkhan, P.

    1966-01-01

    A comparison has been made of the radioisotope dilution-coated charcoal method and a microbiological assay (with L. leichmannii as test organism) for determining the concentration of vitamin B12 in serum. A satisfactory correlation was found between the results of the two methods. Under appropriate conditions the reproducibility of the radioisotope method compared favourably with that of the microbiological method. PMID:5333257

  15. Geophysical methods to support correct water sampling locations for salt dilution gauging

    NASA Astrophysics Data System (ADS)

    Comina, C.; Lasagna, M.; De Luca, D. A.; Sambuelli, L.

    2014-05-01

    To improve water management design, particularly in irrigation areas, it is important to evaluate the baseline state of the water resources, including canal discharge. Discharge measurements, using salt dilution gauging, are a traditional and well-documented technique. The complete mixing of salt used for dilution gauging is required for reliable measurements; this condition is difficult to test or verify and, if not fulfilled, is the largest source of uncertainty in the discharge calculation. In this paper, a geophysical technique (FERT, Fast Electrical Resistivity Tomography) is proposed for imaging the distribution of the salt plume used for dilution gauging at every point along a sampling cross-section. In this way, it is possible to check whether complete mixing has occurred. If the mixing is not complete, the image created by FERT can also provide guidance for selecting water-sampling locations in the sampling cross-section. A water multi-sampling system prototype for the simultaneous sampling of canal water at different points within the cross-section, aimed to potentially take into account concentration variability, is also proposed and tested. Preliminary results of a single test with salt dilution gauging and FERT in a real case are reported. The results show that imaging the passage of the salt plume is possible by means of geophysical controls and that this can potentially help in the selection of water sampling points.

  16. Comparison of E-test with agar dilution methods in testing susceptibility of N. gonorrhoeae to azithromycin.

    PubMed

    Yasin, R M; Suan, K A; Meng, C Y

    1997-05-01

    A single dose of a new antibiotic, azithromycin, has been shown to be effective in the treatment of uncomplicated Neisseria gonorrhoeae. A clinical study was conducted to assess the in vitro susceptibility of N gonorrhoeae to azithromycin and compare the reliability of results obtained using the new E-test methodology for determination of the minimum inhibitory concentration (MIC) of antibiotic with those obtained through the standard agar dilution method. 135 clinical isolates of N gonorrhoeae were obtained from patients attending hospital-based sexually transmitted disease clinics in five geographic locations in Malaysia. 76 of the isolates were penicillinase-producing N gonorrhoeae and 69 were high-level tetracycline-resistant N gonorrhoeae. All isolates were susceptible to azithromycin based on the susceptible MIC breakpoint of 2.0 mcg/ml. The MICs ranged from 0.0078-0.25 mcg/ml by agar dilution method and from 0.016-0.50 mcg/ml by E-test. Agreement between these two methods was 97.8%. The single-dose regime and good antigonococcal and antichlamydial activity of azithromycin make this antibiotic a suitable treatment choice. Moreover, the findings of this study suggest that the simpler, faster E-test is as reliable as the agar dilution method. Given the tendency of the antimicrobial susceptibility pattern of N gonorrhoeae to change rapidly, it is important to monitor MICs to detect the emergence of resistance. PMID:9153733

  17. Campylobacter growth rates in four different matrices: broiler caecal material, live birds, Bolton broth, and brain heart infusion broth

    PubMed Central

    Battersby, Tara; Walsh, Desmond; Whyte, Paul; Bolton, Declan J.

    2016-01-01

    Background The objective of this study was to characterise Campylobacter growth in enrichment broths (Bolton broth, brain heart infusion broth), caecal material (in vitro), and in the naturally infected live broilers (in vivo) in terms of mean lag periods and generation times as well as maximum growth rates and population (cell concentration) achieved. Methods Bolton and brain heart infusion broths and recovered caecal material were inoculated with 10 poultry strains of Campylobacter (eight Campylobacter jejuni and two Campylobacter coli), incubated under microaerobic conditions, and Campylobacter concentrations determined periodically using the ISO 10272:2006 method. Caeca from 10 flocks, infected at first thinning, were used to characterise Campylobacter growth in the live birds. Mean generation times (G) (early lag to exponential phase) were calculated using the formula: G=t/3.3 logb/B. Mean lag times and µmax were calculated using the Micro Fit© Software (Version 1.0, Institute of Food Research). Statistical comparison was performed using GENSTAT ver. 14.1 (VSN International Ltd., Hemel, Hempstead, UK). Results The mean lag periods in Bolton broth, brain heart infusion broth, caecal material, and in the live bird were estimated to be 6.6, 6.7, 12.6, and 31.3 h, respectively. The corresponding mean generation times were 2.1, 2.2, 3.1, and 6.7 h, respectively; maximum growth rates were 0.7, 0.8, 0.4, and 2 generations h−1 and the maximum populations obtained in each matrix were 9.6, 9.9, 7.8, and 7.4 log10 CFU/g, respectively. Conclusion This study provides data on the growth of Campylobacter in a range of laboratory media, caecal contents, and in broilers which may be used to develop predictive models and/or inform science-based control strategies such as the maximum time between flock testing and slaughter, logistical slaughter, and single-stage depopulation of broiler units. PMID:27052025

  18. Accuracy of the Thermo Fisher Scientific (Sensititre™) dry-form broth microdilution MIC product when testing ceftaroline.

    PubMed

    Jones, Ronald N; Holliday, Nicole M; Critchley, Ian A

    2015-04-01

    Ceftaroline, the active metabolite of the ceftaroline fosamil pro-drug, was the first advanced-spectrum cephalosporin with potent activity against methicillin-resistant Staphylococcus aureus to be approved by the US Food and Drug Administration for acute bacterial skin and skin structure infections. After 4 years of clinical use, few ceftaroline commercial susceptibility testing devices other than agar diffusion methods (disks and stable gradient) are available. Here, we validate a broth microdilution product (Sensititre™; Thermo Fisher Scientific, Cleveland, OH, USA) that achieved 99.2% essential agreement (manual and automated reading) and 95.3-100.0% categorical agreement, with high reproducibility (98.0-100.0%). Sensititre™ MIC values for ceftaroline, however, were slightly skewed toward an elevated value (0.5 × log2 dilution step), greatest when testing for streptococci and Enterobacteriaceae. PMID:25623933

  19. Pre-treatment step with Leuconostoc mesenteroides or L. pseudomesenteroides strains removes furfural from Zymomonas mobilis ethanolic fermentation broth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Furfural (furan-2-carboxaldehyde), formed during dilute acid hydrolysis of biomass, is an inhibitor of growth and ethanol production by Zymomonas mobilis. The present study used a biological pre-treatment to reduce that amount of furfural in a model biofuel fermentation broth. The pre-treatment in...

  20. Comparison of isotope dilution and excretion methods for determining the half-life of ascorbic acid in the guinea pig

    SciTech Connect

    Kipp, D.E.; Rivers, J.M.

    1984-08-01

    The half-life of ascorbic acid (AA) in guinea pigs was investigated by the isotope dilution and excretion methods. The dilution method measures (1-14C)AA disappearance from the plasma, whereas the excretion method measures the elimination of (1-14C)AA and the metabolites from the body. Two groups of animals underwent both isotope studies in reverse order. Animals were conditioned to the experimental procedures and fed 2.5 mg AA/100 g body weight orally to maintain a daily intake of the vitamin independent of food consumption. The two isotope procedures imposed similar stress on the animals, as determined by plasma cortisol levels and body weight changes. The AA half-life calculations of the rapidly exchangeable pool by the isotope dilution method yielded values of 1.23 and 0.34 hours for the two groups, respectively. The half-life of the slowly exchangeable pool for the two groups was 60.2 and 65.8 hours, respectively. The half-life of AA in the rapidly exchangeable pool, as measured by the excretion studies, was 4.57-8.75 hours. For the slowly exchangeable pool, it was 146-149 hours. The longer half-life of both pools obtained with the excretion method indicates that the isotope is disappearing from the plasma more rapidly than it is being excreted. This suggests that a portion of the (1-14C)AA leaving the plasma is removed to a body pool that is not sampled by the isotope excretion method.

  1. Dilution space ratio of 2H and 18O of doubly labeled water method in humans.

    PubMed

    Sagayama, Hiroyuki; Yamada, Yosuke; Racine, Natalie M; Shriver, Timothy C; Schoeller, Dale A

    2016-06-01

    Variation of the dilution space ratio (Nd/No) between deuterium ((2)H) and oxygen-18 ((18)O) impacts the calculation of total energy expenditure (TEE) by doubly labeled water (DLW). Our aim was to examine the physiological and methodological sources of variation of Nd/No in humans. We analyzed data from 2,297 humans (0.25-89 yr old). This included the variables Nd/No, total body water, TEE, body mass index (BMI), and percent body fat (%fat). To differentiate between physiologic and methodologic sources of variation, the urine samples from 54 subjects were divided and blinded and analyzed separately, and repeated DLW dosing was performed in an additional 55 participants after 6 mo. Sex, BMI, and %fat did not significantly affect Nd/No, for which the interindividual SD was 0.017. The measurement error from the duplicate urine sample sets was 0.010, and intraindividual SD of Nd/No in repeats experiments was 0.013. An additional SD of 0.008 was contributed by calibration of the DLW dose water. The variation of measured Nd/No in humans was distributed within a small range and measurement error accounted for 68% of this variation. There was no evidence that Nd/No differed with respect to sex, BMI, and age between 1 and 80 yr, and thus use of a constant value is suggested to minimize the effect of stable isotope analysis error on calculation of TEE in the DLW studies in humans. Based on a review of 103 publications, the average dilution space ratio is 1.036 for individuals between 1 and 80 yr of age. PMID:26989221

  2. Accuracy of some routine method used in clinical chemistry as judged by isotope dilution-mass spectrometry

    SciTech Connect

    Bjoerkhem, I.; Bergman, A.; Falk, O.; Kallner, A.; Lantto, O.; Svensson, L.; Akerloef, E.; Blomstrand, R.

    1981-05-01

    Serum from patients was pooled, filtered, dispensed, and frozen. This pooled specimen was used for accuracy control in 64 participating laboratories in Sweden. Mean values (state-of-the-art values) were obtained for creatinine, cholesterol, glucose, urea, uric acid, and cortisol. These values were compared with values obtained with highly accurate reference methods based on isotope dilution-mass spectrometry. Differences were marked in the case of determination of creatinine and cortisol. Concerning the other components, the differences between the state-of-the-art value and the values obtained with the reference methods were negligible. Moreover, the glucose oxidase and the oxime methods for determination of glucose and urea were found to give significantly lower values than the hexokinase and urease methods, respectively. Researchers conclude that methods with a higher degree of accuracy are required for routine determination of creatinine and cortisol.

  3. Use of broth cultures peri-operatively to optimise the microbiological diagnosis of musculoskeletal implant infections.

    PubMed

    Blackmur, J P; Tang, E Y H; Dave, J; Simpson, A H R W

    2014-11-01

    We compared the use of broth culture medium for samples taken in theatre with the standard practice of placing tissue samples in universal containers. A total of 67 consecutive patients had standard multiple samples of deep tissue harvested at surgery and distributed equally in theatre either to standard universal containers or to broth culture medium. These samples were cultured by direct and enrichment methods. The addition of broth in theatre to standard practice led to an increase in sensitivity from 83% to 95% and an increase in negative predictive value from 77% to 91%. Placing tissue samples directly into broth in the operating theatre is a simple, inexpensive way to increase the sensitivity of cultures from infected patients, and does not appear to compromise the specificity of these cultures. PMID:25371476

  4. Development of traceable precision dynamic dilution method to generate dimethyl sulphide gas mixtures at sub-nanomole per mole levels for ambient measurement.

    PubMed

    Kim, Mi Eon; Kim, Yong Doo; Kang, Ji Hwan; Heo, Gwi Suk; Lee, Dong Soo; Lee, Sangil

    2016-04-01

    Dimethyl sulphide (DMS) is an important compound in global atmospheric chemistry and climate change. Traceable international standards are essential for measuring accurately the long-term global trend in ambient DMS. However, developing accurate gas standards for sub-nanomole per mole (nmol/mol) mole fractions of DMS in a cylinder is challenging, because DMS is reactive and unstable. In this study, a dynamic dilution method that is traceable and precise was developed to generate sub-nmol/mol DMS gas mixtures with a dynamic dilution system based on sonic nozzles and a long-term (>5 years) stable 10 μmol/mol parent DMS primary standard gas mixtures (PSMs). The dynamic dilution system was calibrated with traceable methane PSMs, and its estimated dilution factors were used to calculate the mole fractions of the dynamically generated DMS gas mixtures. A dynamically generated DMS gas mixture and a 6 nmol/mol DMS PSM were analysed against each other by gas chromatography with flame-ionisation detection (GC/FID) to evaluate the dilution system. The mole fractions of the dynamically generated DMS gas mixture determined against a DMS PSM and calculated with the dilution factor agreed within 1% at 6 nmol/mol. In addition, the dynamically generated DMS gas mixtures at various mole fractions between 0.4 and 11.7 nmol/mol were analysed by GC/FID and evaluated for their linearity. The analytically determined mole fractions showed good linearity with the mole fractions calculated with the dilution factors. Results showed that the dynamic dilution method generates DMS gas mixtures ranging between 0.4 nmol/mol and 12 nmol/mol with relative expanded uncertainties of less than 2%. Therefore, the newly developed dynamic dilution method is a promising reference method for generating sub-nmol/mol DMS gas standards for accurate ambient measurements. PMID:26838438

  5. Fabrication of Flexible Au/ZnO/ITO/PET Memristor Using Dilute Electrodeposition Method

    NASA Astrophysics Data System (ADS)

    Fauzi, F. B.; Ani, M. H.; Othman, R.; Azhar, A. Z. A.; Mohamed, M. A.; Herman, S. H.

    2015-11-01

    DRAM has been approaching its maximum physical limit due to the demand of smaller size and higher capacity memory resistor. The researchers have discovered the abilities of a memristor, a Non Volatile Memory (NVM) that could overcome the size and capacity obstacles. This paper discussed about the deposition of zinc oxide (ZnO) on indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrate by electrodeposition. Metallic Zn film was deposited on substrates with varying deposition time from 15 to 120 seconds in very dilute zinc chloride (ZnCl2) aqueous and subsequently oxidized at 150 °C to form ZnO/ITO coated PET junction. The deposited thin film was characterized via x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The results from I-V measurement show the deposited ZnO exhibits pinched hysteresis loop. The hysteresis loop becomes smaller with increasing deposition time. The 15 seconds electrodeposition gave the largest hysteresis loop and largest value of resistive switching ratio of 1.067. The result of the synthesized ZnO on the flexible substrate can be one of the alternatives to replace the current memory system as the flexible memory system.

  6. Use of a {sup 15}N isotope dilution method to assess contaminant effects on soil nitrification

    SciTech Connect

    Nason, G.E.; Dinwoodie, G.D.

    1995-12-31

    Ecologically relevant bioassays are needed to assess effects of contaminants on soil processes such as decomposition and nutrient cycling. This study was conducted to assess the potential of a soil-based nitrification bioassay. Soil samples adjusted to 0.03 MPa moisture content were amended with 0.1, 1.0, 10 and 100 mg kg{sup {minus}1} PCP or PCB, and 0.05, 0.5, 5 and 50 mg kg{sup {minus}1} Hg and preincubated for 7 days. A 2-d incubation was then started by addition of 10 mg kg{sup {minus}1} {sup 15}NO{sub 3}-N. Diethyl ether used as a carrier for PCP addition had little effect on inorganic nitrogen concentrations during the incubation. Net nitrogen mineralization and nitrification were unaffected by PCB. Higher amendment levels of both PCP and Hg resulted in increases in ammonium concentrations and decreases in net nitrification. {sup 15}N-nitrate pool dilution was sensitive to contamination and showed some gross nitrification was occurring even when net nitrification had ceased. Recoveries of Hg and PCB at the end of the study were greater than 90%. Recovery of PCP was 5%. Incubations carried out under sterile and non-sterile conditions indicated that both sorption and biological degradation were factors in the low PCP recovery.

  7. Post-mining deterioration of bauxite overburdens in Jamaica: storage methods or subsoil dilution?

    NASA Astrophysics Data System (ADS)

    Harris, Mark A.; Omoregie, Samson N.

    2008-03-01

    Rapid degradation of disturbed soil from a karst bauxite mine in Jamaica was recorded. Substantial macronutrient losses were incurred during a short (1 month) or a long (12 months) storage of the replaced topsoils during frequent wet/dry changes. The results suggested very high rates (>70% in the first year) of soil degradation from storage, alongside moderate rates (30%) within the same storage dump. However, higher levels of soil organic matter (SOM) were indicated just below the surface, compared with the surface horizons. It was unlikely that under a high leaching humid tropical rainfall regime, natural degradation processes could have re-emplaced such material firmly intact in the 15-30 cm zone. It was therefore concluded that these SOM anomalies were due to mechanical dilution of surface soil with subsoil material during overburden removal and emplacement rather than from long storage. Increasing the soil organic content during storage could be one corrective approach. However, it is far less costly to exercise greater care to apply more precise overburden removal and emplacement techniques initially, than it is to correct the results of topsoil contamination with subsoil. Although this study was limited to one mine, in the context of imminent large-scale mining expansion and current practices, further investigations are needed to accurately ascertain the proportion of similar subsoil contamination in other bauxite-mined sites.

  8. A practical method for cell-free protein synthesis to avoid stable isotope scrambling and dilution.

    PubMed

    Yokoyama, Jun; Matsuda, Takayoshi; Koshiba, Seizo; Tochio, Naoya; Kigawa, Takanori

    2011-04-15

    During recent years, the targets of protein structure analysis using nuclear magnetic resonance spectroscopy have become larger and more complicated. As a result, a complete and precise stable isotope labeling technique has been desired. A cell-free protein synthesis system is appropriate for this purpose. In the current study, we achieved precise and complete (15)N and (2)H labeling using an Escherichia coli cell extract-based cell-free protein synthesis system by controlling the metabolic reactions in the system with their chemical inhibitors. The addition of aminooxyacetate, d-malate, l-methionine sulfoximine, S-methyl-l-cysteine sulfoximine, 6-diazo-5-oxo-l-norleucine, and 5-diazo-4-oxo-l-norvaline was quite effective for precise amino acid-selective (15)N labeling even for aspartic acid, asparagine, glutamic acid, and glutamine, which generally suffer from severe isotope scrambling and dilution when using the conventional cell-free system. For (2)H labeling, the back-protonation of the H(α) and H(β) positions, which commonly occurred in the conventional system, was dramatically suppressed by simply adding aminooxyacetate and d-malate to the cell-free system except for the H(α) positions in methionine and cysteine. PMID:21256106

  9. Investigation of electrolyte measurement in diluted whole blood using spectroscopic and chemometric methods

    NASA Technical Reports Server (NTRS)

    Soller, Babs R.; Favreau, Janice; Idwasi, Patrick O.

    2003-01-01

    The feasibility of using near-infrared (NIR) spectroscopy in combination with partial least-squares (PLS) regression was explored to measure electrolyte concentration in whole blood samples. Spectra were collected from diluted blood samples containing randomized, clinically relevant concentrations of Na+, K+, and Ca2+. Sodium was also studied in lysed blood. Reference measurements were made from the same samples using a standard clinical chemistry instrument. Partial least squares (PLS) was used to develop calibration models for each ion with acceptable results (Na+, R2 = 0.86, CVSEP = 9.5 mmol/L; K+, R2 = 0.54, CVSEP = 1.4 mmol/L; Ca2+, R2 = 0.56, CVSEP = 0.18 mmol/L). Slightly improved results were obtained using a narrower wavelength region (470-925 nm) where hemoglobin, but not water, absorbed indicating that ionic interaction with hemoglobin is as effective as water in causing measurable spectral variation. Good models were also achieved for sodium in lysed blood, illustrating that cell swelling, which is correlated with sodium concentration, is not required for calibration model development.

  10. Quantification of Nitrous Oxide from Fugitive Emissions by Tracer Dilution Method using a Mobile Real-time Nitrous Oxide Analyzer

    NASA Astrophysics Data System (ADS)

    Mønster, J.; Rella, C.; Jacobson, G. A.; He, Y.; Hoffnagle, J.; Scheutz, C.

    2012-12-01

    Nitrous oxide is a powerful greenhouse gas considered 298 times stronger than carbon dioxide on a hundred years term (Solomon et al. 2007). The increasing global concentration is of great concern and is receiving increasing attention in various scientific and industrial fields. Nitrous oxide is emitted from both natural and anthropogenic sources. Inventories of source specific fugitive nitrous oxide emissions are often estimated on the basis of modeling and mass balance. While these methods are well-developed, actual measurements for quantification of the emissions can be a useful tool for verifying the existing estimation methods as well as providing validation for initiatives targeted at lowering unwanted nitrous oxide emissions. One approach to performing such measurements is the tracer dilution method (Galle et al. 2001), in which a tracer gas is released at the source location at a known flow. The ratio of downwind concentrations of both the tracer gas and nitrous oxide gives the ratios of the emissions rates. This tracer dilution method can be done with both stationary and mobile measurements; in either case, real-time measurements of both tracer and analyte gas is required, which places high demands on the analytical detection method. To perform the nitrous oxide measurements, a novel, robust instrument capable of real-time nitrous oxide measurements has been developed, based on cavity ring-down spectroscopy and operating in the near-infrared spectral region. We present the results of the laboratory and field tests of this instrument in both California and Denmark. Furthermore, results are presented from measurements using the mobile plume method with a tracer gas (acetylene) to quantify the nitrous oxide and methane emissions from known sources such as waste water treatment plants and composting facilities. Nitrous oxide (blue) and methane (yellow) plumes downwind from a waste water treatment facility.

  11. Is demineralization with dilute hydrofluoric acid a viable method for isolating mineral stabilized soil organic matter?

    NASA Astrophysics Data System (ADS)

    Sanderman, J.; Baldock, J.; Farrell, M.; Macreadie, P.; McGowan, J.

    2015-12-01

    While you might not be able to dispose of a body with hydrofluoric acid (HF), as fans of Breaking Bad know HF will break silicon-oxygen bonds. These dual properties make HF a powerful tool in investigations of soil organic matter (SOM). When a soil sample is treated with HF, any low molecular weight OM that was bound to mineral surfaces will be released into solution allowing study of the amount and composition of this stable SOM pool. In the work presented here, we take advantage of this property of HF to explore if different forms of SOM are becoming stabilized to mineral surfaces in terrestrial and marine environments. Difference spectra obtained from solid-state 13C NMR spectroscopic analysis of bulk and 10% HF treated soil samples suggest that in aerobic terrestrial environments alkyl-C and aryl-C compounds can dominate the mineral stabilized fraction. However, in anoxic coastal environments this fraction is dominated by O-alkyl C. Demineralization of soil samples with HF is often necessary for removing paramagnetic interferences and concentrating carbon prior to obtaining NMR spectra. The working assumption using dilute HF is that the resultant SOM chemistry determined by NMR spectroscopy has not been significantly biased by the HF treatment process. This assumption has been validated in several studies but also refuted in others. A second goal of this study was to revisit this critical assumption by looking at carbon loss and resulting 13C NMR chemistry from a diverse set of soils and organic materials using HF in 2% and 10% concentrations. We found that 10% HF resulted in slightly greater loss of C than 2% HF but in cases where a preferential shift in chemistry was observed it was observed in both the 2% and 10% treatments. The implications of both of these findings will be discussed in the context of understanding the sources, stability and potential loss mechanisms of mineral stabilized SOM.

  12. Comparing Etest and Broth Microdilution for Antifungal Susceptibility Testing of the Most-Relevant Pathogenic Molds

    PubMed Central

    Lamoth, Frédéric

    2015-01-01

    Invasive mold infections are life-threatening diseases for which appropriate antifungal therapy is crucial. Their epidemiology is evolving, with the emergence of triazole-resistant Aspergillus spp. and multidrug-resistant non-Aspergillus molds. Despite the lack of interpretive criteria, antifungal susceptibility testing of molds may be useful in guiding antifungal therapy. The standard broth microdilution method (BMD) is demanding and requires expertise. We assessed the performance of a commercialized gradient diffusion method (Etest method) as an alternative to BMD. The MICs or minimal effective concentrations (MECs) of amphotericin B, voriconazole, posaconazole, caspofungin, and micafungin were assessed for 290 clinical isolates of the most representative pathogenic molds (154 Aspergillus and 136 non-Aspergillus isolates) with the BMD and Etest methods. Essential agreements (EAs) within ±2 dilutions of ≥90% between the two methods were considered acceptable. EAs for amphotericin B and voriconazole were >90% for most potentially susceptible species. For posaconazole, the correlation was acceptable for Mucoromycotina but Etest MIC values were consistently lower for Aspergillus spp. (EAs of <90%). Excellent EAs were found for echinocandins with highly susceptible (MECs of <0.015 μg/ml) or intrinsically resistant (MECs of >16 μg/ml) strains. However, MEC determinations lacked consistency between methods for strains exhibiting mid-range MECs for echinocandins. We concluded that the Etest method is an appropriate alternative to BMD for antifungal susceptibility testing of molds under specific circumstances, including testing with amphotericin B or triazoles for non-Aspergillus molds (Mucoromycotina and Fusarium spp.). Additional study of molecularly characterized triazole-resistant Aspergillus isolates is required to confirm the ability of the Etest method to detect voriconazole and posaconazole resistance among Aspergillus spp. PMID:26202113

  13. Contribution of the finite volume point dilution method for measurement of groundwater fluxes in a fractured aquifer.

    PubMed

    Jamin, P; Goderniaux, P; Bour, O; Le Borgne, T; Englert, A; Longuevergne, L; Brouyère, S

    2015-11-01

    Measurement of groundwater fluxes is the basis of all hydrogeological study, from hydraulic characterization to the most advanced reactive transport modeling. Usual groundwater flux estimation with Darcy's law may lead to cumulated errors on spatial variability, especially in fractured aquifers where local direct measurement of groundwater fluxes becomes necessary. In the present study, both classical point dilution method (PDM) and finite volume point dilution method (FVPDM) are compared on the fractured crystalline aquifer of Ploemeur, France. The manipulation includes the first use of the FVPDM in a fractured aquifer using a double packer. This configuration limits the vertical extent of the tested zone to target a precise fracture zone of the aquifer. The result of this experiment is a continuous monitoring of groundwater fluxes that lasted for more than 4 days. Measurements of groundwater flow rate in the fracture (Q(t)) by PDM provide good estimates only if the mixing volume (V(w)) (volume of water in which the tracer is mixed) is precisely known. Conversely, the FVPDM allows for an independent estimation of V(w) and Q(t), leading to better precision in case of complex experimental setup such as the one used. The precision of a PDM does not rely on the duration of the experiment while a FVPDM may require long experimental duration to guarantees a good precision. Classical PDM should then be used for rapid estimation of groundwater flux using simple experimental setup. On the other hand, the FVPDM is a more precise method that has a great potential for development but may require longer duration experiment to achieve a good precision if the groundwater fluxes investigated are low and/or the mixing volume is large. PMID:26519822

  14. Contribution of the finite volume point dilution method for measurement of groundwater fluxes in a fractured aquifer

    NASA Astrophysics Data System (ADS)

    Jamin, P.; Goderniaux, P.; Bour, O.; Le Borgne, T.; Englert, A.; Longuevergne, L.; Brouyère, S.

    2015-11-01

    Measurement of groundwater fluxes is the basis of all hydrogeological study, from hydraulic characterization to the most advanced reactive transport modeling. Usual groundwater flux estimation with Darcy's law may lead to cumulated errors on spatial variability, especially in fractured aquifers where local direct measurement of groundwater fluxes becomes necessary. In the present study, both classical point dilution method (PDM) and finite volume point dilution method (FVPDM) are compared on the fractured crystalline aquifer of Ploemeur, France. The manipulation includes the first use of the FVPDM in a fractured aquifer using a double packer. This configuration limits the vertical extent of the tested zone to target a precise fracture zone of the aquifer. The result of this experiment is a continuous monitoring of groundwater fluxes that lasted for more than 4 days. Measurements of groundwater flow rate in the fracture (Qt) by PDM provide good estimates only if the mixing volume (Vw) (volume of water in which the tracer is mixed) is precisely known. Conversely, the FVPDM allows for an independent estimation of Vw and Qt, leading to better precision in case of complex experimental setup such as the one used. The precision of a PDM does not rely on the duration of the experiment while a FVPDM may require long experimental duration to guarantees a good precision. Classical PDM should then be used for rapid estimation of groundwater flux using simple experimental setup. On the other hand, the FVPDM is a more precise method that has a great potential for development but may require longer duration experiment to achieve a good precision if the groundwater fluxes investigated are low and/or the mixing volume is large.

  15. Dilution Confusion: Conventions for Defining a Dilution

    ERIC Educational Resources Information Center

    Fishel, Laurence A.

    2010-01-01

    Two conventions for preparing dilutions are used in clinical laboratories. The first convention defines an "a:b" dilution as "a" volumes of solution A plus "b" volumes of solution B. The second convention defines an "a:b" dilution as "a" volumes of solution A diluted into a final volume of "b". Use of the incorrect dilution convention could affect…

  16. Determination of niobium in rocks by an isotope dilution spectrophotometric method

    USGS Publications Warehouse

    Greenland, L.P.; Campbell, E.Y.

    1970-01-01

    Rocks and minerals are fused with sodium peroxide in the presence of carrierfree 95Nb. The fusion cake is leached with water and the precipitate dissolved in hydrofluoric-sulfuric acid mixture. Niobium is extracted into methyl isobutyl ketone and further purified by ion exchange. The amount of niobium is determined spectrophotometrically with 4-(2-pyridylazo)-resorcinol, and the chemical yield of the separations determined by counting 95Nb. This procedure is faster and less sensitive to interferences than previously proposed methods for determining niobium in rocks.The high purity of the separated niobium makes the method applicable to nearly all matrices. ?? 1970.

  17. Comparison of E-test with broth microdilution and disk diffusion for susceptibility testing of coryneform bacteria.

    PubMed

    Martínez-Martínez, L; Ortega, M C; Suárez, A I

    1995-05-01

    The susceptibilities of 135 coryneform bacteria isolated from clinical samples to ampicillin (AMP), cephalothin (CR), cefoxitin (FOX), cefotaxime (CTX), erythromycin (E), ciprofloxacin (CIP), tetracycline (TE), amikacin (AK), vancomycin (VA), and rifampin (R) were determined by disk diffusion, broth microdilution, and the E-test. The following species (number of isolates in parentheses) were included: Corynebacterium urealyticum (30), Corynebacterium minutissimum (20), coryneform CDC group ANF-1 (20), Corynebacterium striatum (20), Corynebacterium jeikeium (15), coryneform CDC group I2 (8), Listeria monocytogenes (7), Corynebacterium xerosis (5), and other coryneform bacteria (10). Agreement within one twofold dilution between the E-test and broth microdilution was 31% (VA), 64% (AK), 71% (CTX), 77% (FOX and CIP), 79% (TE), 84% (AMP), 87% (E), and 88% (CR and R). For the 1,350 combinations of microorganisms and antimicrobial agents, 85 (6.3%) discrepancies in interpretive category were found (4.2% minor, 1.2% major, and 0.9% very major). Seventy (5.1%) disagreements in interpretive category were found between disk diffusion and the E-test (3.8% minor, 0.4% major, and 0.9% very major), and 85 (6.3%) disagreements were found between microdilution (reference method) and disk diffusion (4.2% minor, 0.5% major, and 1.5% very major). MICs obtained with the E-test were highly reproducible. No category discrepancy was observed for VA, despite quantitative results. Considering interpretive categories, there is a good overall agreement between the three methods studied here, but further evaluation of current methodologies for susceptibility testing is required when considering coryneform bacteria and determination of quantitative activity of antimicrobial agents. PMID:7615748

  18. A simplified dilution method for detection of Campylobacter in broiler ceca

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Campylobacter species, a leading foodborne pathogen, is linked to poultry. Development of intervention strategies depends on the ability to rapidly and consistently recover and estimate the number of bacteria present. The objective of this experim ent was to validate a semi-quantitative method for d...

  19. Development of a stable isotope dilution LC-MS/MS method for the Alternaria toxins tentoxin, dihydrotentoxin, and isotentoxin.

    PubMed

    Liu, Yang; Rychlik, Michael

    2013-03-27

    For the Alternaria toxins tentoxin, dihydrotentoxin, and isotentoxin, a stable isotope dilution LC-MS/MS method was first developed. Triply deuterated internal standards were prepared via total synthesis and introducing the labels in the last step before cyclization. Method validation was carried out by using potato starch, tomato puree, and white pepper powder as blank matrices. For the three toxins the limits of detection ranged from 0.10 to 0.99 μg/kg. The inter-/intraday relative standard deviations of the method were below 8.8%, and the recoveries ranged between 98 and 115%. Although cyclic peptides are known to show only negligible fragmentation, a low limit of detection was achieved with the optimization of mass spectrometry parameters and cleanup on C18-phenyl SPE columns providing a more selective binding of these phenyl-containing cyclic peptides. The method was applied to 103 food samples including bread, cereals, chips, juice, nuts, oil, sauce, seeds, and spices. Of these, 85% were contaminated with tentoxin and 55% were contaminated with dihydrotentoxin, whereas isotentoxin was not quantifiable. Maximal concentrations of tentoxin and dihydrotentoxin were 52.4 and 36.3 μg/kg, respectively, and were both detected in paprika powder. PMID:23432357

  20. An Evaluation Method for the Suppression of Pathogenic Fusarium oxysporum by Soil Microorganisms Using the Dilution Plate Technique

    PubMed Central

    Mitsuboshi, Masahiro; Kioka, Yuuzou; Noguchi, Katsunori; Asakawa, Susumu

    2016-01-01

    Soil-borne diseases caused by pathogenic microorganisms are one of the main factors responsible for the decline in crop yields in farmlands. Pathogenic Fusarium oxysporum causes serious damage to various crops, and, thus, a feasible diagnostic method for soil-borne diseases is required. We herein examined a simple method to evaluate the suppressiveness of soil microorganisms against a pathogen by co-cultivating indigenous soil microorganisms and a pathogenic fungus (F. oxysporum f. sp. spinaciae). We inoculated F. oxysporum onto the center of agar medium plates mixed with a dilution series of a suspension of organic fertilizers or soil. After an approximately one-week cultivation, the growth degree of F. oxysporum was estimated based on the size of the colonies that formed on the plates. The growth degree of F. oxysporum significantly differed among the organic fertilizers tested, indicating the usefulness of the method for evaluating suppressiveness by organic fertilizers. Differences in the growth degrees of F. oxysporum were associated with the incidence of disease in spinach on soil treated with organic fertilizers and inoculated with a pathogenic F. oxysporum strain. These results suggested that this method provides some useful information on the suppressiveness of organic fertilizers and soil against Fusarium wilt. PMID:27558588

  1. Rapid detection of Clostridium perfringens: comparison of lactose sulfite broth with tryptose-sulfite-cycloserine agar.

    PubMed

    Neut, C; Pathak, J; Romond, C; Beerens, H

    1985-01-01

    The lactose sulfite (LS) medium recommended for the detection and identification of Clostridium perfringens in foods was compared with a reference method using tryptose-sulfite-cycloserine (TSC) agar for the enumeration of this organism in a variety of foods and food ingredients. C. perfringens was detected and enumerated in 17 of the 54 samples examined with LS broth, but its presence could be confirmed in only 9 of the samples with TSC agar. In only 2 instances, C. perfringens was detected on TSC agar but not in LS broth. A positive response (FeS + and gas +) in LS broth incubated at 46 degrees C always corresponded to the presence of C. perfringens; whereas the black colonies formed on TSC agar incubated at 37 degrees C were frequently found to be Clostridium species other than C. perfringens. Thus, because of its highly selective nature, LS broth was superior to TSC agar for enumerating and confirming the small numbers of C. perfringens that were present in a majority of the samples. This was especially true when other clostridia were also present. Besides its greater selectivity and sensitivity, LS broth had the additional advantages of requiring less work and giving confirmed results within 24-48 h compared with 3 days for the TSC agar method. PMID:2865247

  2. Method for control of NOx emission from combustors using fuel dilution

    DOEpatents

    Schefer, Robert W.; Keller, Jay O

    2007-01-16

    A method of controlling NOx emission from combustors. The method involves the controlled addition of a diluent such as nitrogen or water vapor, to a base fuel to reduce the flame temperature, thereby reducing NOx production. At the same time, a gas capable of enhancing flame stability and improving low temperature combustion characteristics, such as hydrogen, is added to the fuel mixture. The base fuel can be natural gas for use in industrial and power generation gas turbines and other burners. However, the method described herein is equally applicable to other common fuels such as coal gas, biomass-derived fuels and other common hydrocarbon fuels. The unique combustion characteristics associated with the use of hydrogen, particularly faster flame speed, higher reaction rates, and increased resistance to fluid-mechanical strain, alter the burner combustion characteristics sufficiently to allow operation at the desired lower temperature conditions resulting from diluent addition, without the onset of unstable combustion that can arise at lower combustor operating temperatures.

  3. Sensitive isotope dilution liquid chromatography/electrospray ionization tandem mass spectrometry method for the determination of acrylamide in chocolate.

    PubMed

    Ren, Yiping; Zhang, Yu; Jiao, Jingjing; Cai, Zengxuan; Zhang, Ying

    2006-03-01

    Isotope dilution liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-MS/MS) was applied to the quantification of acrylamide in chocolate matrixes (dark chocolate, milk chocolate, chocolate with nuts, chocolate with almonds, and chocolate with wheat best element). The method included defatting with petroleum ether, extracting with aqueous solution of 2 mol l(-1) sodium chloride and clean-up by solid-phase (SPE) with OASIS HLB 6 cm3 cartridges. Acrylamide was detected with an Atlantis dC18 5 microm 210 x 1.5 mm column using 10% methanol/0.1% formic acid in water as the mobile phase. The analytical method was in-house validated and good results were obtained with respect to repeatability (RSD < 3.5%) and recovery (86-93%), which fulfilled the requirements defined by European Union legislation. The acrylamide levels in chocolate were 23-537 microg kg(-1). Therefore, the method was successfully used for the quantitative analysis of acrlyamide in various chocolate products. PMID:16517524

  4. Optical absorption of dilute nitride alloys using self-consistent Green's function method

    NASA Astrophysics Data System (ADS)

    Seifikar, Masoud; O'Reilly, Eoin P.; Fahy, Stephen

    2014-01-01

    We have calculated the optical absorption for InGaNAs and GaNSb using the band anticrossing (BAC) model and a self-consistent Green's function (SCGF) method. In the BAC model, we include the interaction of isolated and pair N levels with the host matrix conduction and valence bands. In the SCGF approach, we include a full distribution of N states, with non-parabolic conduction and light-hole bands, and parabolic heavy-hole and spin-split-off bands. The comparison with experiments shows that the first model accounts for many features of the absorption spectrum in InGaNAs; including the full distribution of N states improves this agreement. Our calculated absorption spectra for GaNSb alloys predict the band edges correctly but show more features than are seen experimentally. This suggests the presence of more disorder in GaNSb alloys in comparison with InGaNAs.

  5. Can the single-breath helium dilution method predict lung volumes as measured by whole-body plethysmography?*

    PubMed Central

    Coertjens, Patrícia Chaves; Knorst, Marli Maria; Dumke, Anelise; Pasqualoto, Adriane Schmidt; Riboldi, João; Barreto, Sérgio Saldanha Menna

    2013-01-01

    OBJECTIVE: To compare TLC and RV values obtained by the single-breath helium dilution (SBHD) method with those obtained by whole-body plethysmography (WBP) in patients with normal lung function, patients with obstructive lung disease (OLD), and patients with restrictive lung disease (RLD), varying in severity, and to devise equations to estimate the SBHD results. METHODS: This was a retrospective cross-sectional study involving 169 individuals, of whom 93 and 49 presented with OLD and RLD, respectively, the remaining 27 having normal lung function. All patients underwent spirometry and lung volume measurement by both methods. RESULTS: TLC and RV were higher by WBP than by SBHD. The discrepancy between the methods was more pronounced in the OLD group, correlating with the severity of airflow obstruction. In the OLD group, the correlation coefficient of the comparison between the two methods was 0.57 and 0.56 for TLC and RV, respectively (p < 0.001 for both). We used regression equations, adjusted for the groups studied, in order to predict the WBP values of TLC and RV, using the corresponding SBHD values. It was possible to create regression equations to predict differences in TLC and RV between the two methods only for the OLD group. The TLC and RV equations were, respectively, ∆TLCWBP-SBHD in L = 5.264 − 0.060 × FEV1/FVC (r2 = 0.33; adjusted r2 = 0.32) and ∆RVWBP-SBHD in L = 4.862 − 0.055 × FEV1/FVC (r2 = 0.31; adjusted r2 = 0.30). CONCLUSIONS: The correction of TLC and RV results obtained by SBHD can improve the accuracy of this method for assessing lung volumes in patients with OLD. However, additional studies are needed in order to validate these equations. PMID:24473761

  6. Optimized, one-step, recovery-enrichment broth for enhanced detection of Listeria monocytogenes in pasteurized milk and hot dogs.

    PubMed

    Knabel, Stephen J

    2002-01-01

    A one-step, recovery-enrichment broth, optimized Penn State University (oPSU) broth, was developed to consistently detect low levels of injured and uninjured Listeria monocytogenes cells in ready-to-eat foods. The oPSU broth contains special selective agents that inhibit growth of background flora without inhibiting recovery of injured Listeria cells. After recovery in the anaerobic section of oPSU broth, Listeria cells migrated to the surface, forming a black zone. This migration separated viable from nonviable cells and the food matrix, thereby reducing inhibitors that prevent detection by molecular methods. The high Listeria-to-background ratio in the black zone resulted in consistent detection of low levels of L. monocytogenes in pasteurized foods by both cultural and molecular methods, and greatly reduced both false-negative and false-positive results. oPSU broth does not require transfer to a secondary enrichment broth, making it less laborious and less subject to external contamination than 2-step enrichment protocols. Addition of 150mM D-serine prevented germination of Bacillus spores, but not the growth of vegetative cells. Replacement of D-serine with 12 mg/L acriflavin inhibited growth of vegetative cells of Bacillus spp. without inhibiting recovery of injured Listeria cells. oPSU broth may allow consistent detection of low levels of injured and uninjured cells of L. monocytogenes in pasteurized foods containing various background microflora. PMID:11990038

  7. A facile stable-isotope dilution method for determination of sphingosine phosphate lyase activity.

    PubMed

    Suh, Jung H; Eltanawy, Abeer; Rangan, Apoorva; Saba, Julie D

    2016-01-01

    A new technique for quantifying sphingosine phosphate lyase activity in biological samples is described. In this procedure, 2-hydrazinoquinoline is used to convert (2E)-hexadecenal into the corresponding hydrazone derivative to improve ionization efficiency and selectivity of detection. Combined utilization of liquid chromatographic separation and multiple reaction monitoring-mass spectrometry allows for simultaneous quantification of the substrate S1P and product (2E)-hexadecenal. Incorporation of (2E)- d5-hexadecenal as an internal standard improves detection accuracy and precision. A simple one-step derivatization procedure eliminates the need for further extractions. Limits of quantification for (2E)-hexadecenal and sphingosine-1-phosphate are 100 and 50fmol, respectively. The assay displays a wide dynamic detection range useful for detection of low basal sphingosine phosphate lyase activity in wild type cells, SPL-overexpressing cell lines, and wild type mouse tissues. Compared to current methods, the capacity for simultaneous detection of sphingosine-1-phosphate and (2E)-hexadecenal greatly improves the accuracy of results and shows excellent sensitivity and specificity for sphingosine phosphate lyase activity detection. PMID:26408264

  8. Quality control ranges for testing broth microdilution susceptibility of Flavobacterium columnare and F. psychrophilium to nine antimicrobials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A multi-laboratory broth microdilution method trial was performed to standardize the specialized test conditions required for fish pathogens Flavobacterium columnare and F. pyschrophilum. Nine laboratories tested the quality control (QC) strains Escherichia coli ATCC 25922 and Aeromonas salmonicid...

  9. A method for the routine determination of methylmercury in marine tissue by GC isotope dilution-ICP-MS.

    PubMed

    Valdersnes, Stig; Maage, Amund; Fliegel, Daniel; Julshamn, Kåre

    2012-01-01

    Currently, there is no legal limit for methyl mercury (MeHg) in food; thus, no standardized method for the determination of MeHg in seafood exists within the European jurisdiction. In anticipation of a future legislative limit an inductively coupled plasma isotope dilution mass spectrometry (GC-ICP-ID-MS) method was developed in collaboration with the European Standardization Organization (CEN). The method comprises spiking the tissue sample with Me201Hg, followed by decomposition with tetramethylammonium hydroxide, pH adjustment and derivatization with sodium tetraethylborate, and finally organic extraction of the derivatized MeHg in a hexane phase. Subsequently, the sample is analyzed via GC-ICP-MS and the result calculated using the ID equation. The working range of the method was 0.0005-1.321 mg/kg MeHg in marine tissue, with an internal reproducibility (RSD) of 12-1%. The method was validated based on statistical measures, such as the z-scores, using the commercially available reference materials from National Institute of Standards and Technology Standard Reference Material (NIST SRM) 1566b, NIST SRM 2977 and National Research Council of Canada (NRCC) TORT 2, NRCC, DORM 3, NRCC DOLT 4, and European Reference Material (ERM) CE 464. Z-scores for all standard reference materials, except for NIST SRM 1566b, were better than 11.51. The wide range of marine tissues used during the validation ensures that the method will be applicable for measuring of MeHg in seafood matrixes of all kinds. PMID:22970590

  10. Isotope dilution gas chromatographic-mass spectrometric method for the determination of isoflavonoids, coumestrol, and lignans in food samples.

    PubMed

    Mazur, W; Fotsis, T; Wähälä, K; Ojala, S; Salakka, A; Adlercreutz, H

    1996-01-15

    We present a method for the quantitative determination of the phytoestrogens formononetin, biochanin A, daidzein, genistein, and coumestrol and simultaneously the lignans secoisolariciresinol (SECO) and matairesinol in plant-derived foods. These compounds are measured by isotope dilution gas chromatography-mass spectrometry in the selected ion monitoring mode (ID/GC/MS/SIM) using synthesized deuterated internal standards for the correction of losses during the procedure. A three-step hydrolysis--a rehydration with distilled H2O, followed by enzymatic and acid hydrolysis--has been applied in order to convert the diphenolic glycosides into their respective aglycones. Purification and separation are carried out in two ion-exchange chromatographic steps followed by derivatization and GC-MS. The within-assay imprecision values vary 3.1-9.6% and the between-assay imprecision 7.0-21.2%. The mean recovery of authentic standards processed through the whole procedure varied from 95.5 to 105.5%. Values for some different food samples are presented. The simultaneous determination of the biologically most interesting phytoestrogens and lignans in foods has not been carried out previously and the method will be useful for screening of important foods in populations with different risk of cancer and coronary heart disease, and for metabolic studies. PMID:8789715

  11. Growth of healthy and sanitizer-injured Salmonella cells on mung bean sprouts in different commercial enrichment broths.

    PubMed

    Zheng, Qianwang; Mikš-Krajnik, Marta; D'Souza, Craig; Yang, Yishan; Heo, Da-Jeong; Kim, Si-Kyung; Lee, Seung-Cheol; Yuk, Hyun-Gyun

    2015-12-01

    The ability of nine commercial broths to enrich healthy and 90% sanitizer-injured Salmonella Typhimurium and Salmonella cocktail on mung bean sprouts was evaluated to select an optimum broth for detection. Results showed that S. Typhimurium multiplied faster and reached a higher population in buffered peptone water (BPW), Salmonella AD media (AD) and ONE broth-Salmonella (OB), compared with other broths. Healthy and 90% sanitizer-injured Salmonella at low concentrations increased by 4.0 log CFU/ml in these three broths. However, no Salmonella growth was observed in lactose broth (LB). Further investigation showed that during incubation, pH of LB dropped from 6.7 to 4.2, due to production of lactic (66 mM) and acetic acids (62 mM) by lactic acid bacteria that were identified as dominant microbiota in bean sprouts. Though no cell membrane damage was detected by propidium monoazide combined with real-time PCR, it was found that LB inhibited Salmonella growth, especially from low inoculum levels. This study suggests that in consideration of effectiveness and cost, BPW would be a suitable enrichment broth to use for isolating and detecting Salmonella on mung bean sprouts, while using LB might cause false negative results in Salmonella detection by either PCR or standard cultural method. PMID:26338131

  12. Chemical Constituents of the Culture Broth of Phellinus linteus and Their Antioxidant Activity

    PubMed Central

    Lee, Myeong-Seok; Hwang, Byung Soon; Lee, In-Kyoung; Seo, Geon-Sik

    2015-01-01

    The medicinal fungus Phellinus linteus, in the family Hymenochaetaceae, has been used as a traditional medicine for the treatment of various diseases. In this study, the chemical constituents of the culture broth of P. linteus were investigated. P. linteus was cultured in potato dextrose broth medium, and the culture broth was extracted with ethyl acetate. The ethyl acetate-soluble portion was concentrated and subjected to ODS column chromatography, followed by Sephadex LH-20 column chromatography. Six compounds (1~6) were purified by preparative reversed-phase high-performance liquid chromatography. Spectroscopic methods identified their structures as caffeic acid (1), inotilone (2), 4-(3,4-dihydroxyphenyl)-3-buten-2-one (3), phellilane H (4), (2E,4E)-(+)-4'-hydroxy-γ-ionylideneacetic acid (5), and (2E,4E)-γ-ionylideneacetic acid (6). Compounds 1, 2, and 3 exhibited potent dose-dependent antioxidant activity. PMID:25892914

  13. An Isotope Dilution Method for High-frequency Measurements of Dissolved Inorganic Carbon concentration in the Surface Ocean

    NASA Astrophysics Data System (ADS)

    Huang, K.; Bender, M. L.; Wanninkhof, R. H.; Cassar, N.

    2013-12-01

    Dissolved inorganic carbon (DIC) is one of the most important species in the ocean carbon system. An autonomous system using isotope dilution as its core method has been developed to obtain high-frequency measurements of dissolved inorganic carbon (DIC) concentrations in the surface ocean. This system accurately mixes a seawater sample and a 13C-labeled sodium bicarbonate solution (spike). The mixed solution is then acidified and sent through a gas permeable membrane contactor. CO2 derived from DIC in the mixture is extracted by a CO2-free gas stream, and is sent to a cavity ring-down spectrometer to analyze its 13C/12C ratio. [DIC] of the seawater can then be derived from the measured 13C/12C, the known mixing ratio and the [DI13C] of the spike. The method has been tested under a wide [DIC] range (1800-2800 μmol/kg) in the laboratory. It has also been deployed on a cruise that surveyed ocean waters to the south of Florida. At a sampling resolution of 4 minutes (15 samples per hour), the relative standard deviation of DIC determined from the laboratory tests and the field deployment is ×0.07% and ×0.09%, respectively. The accuracy of the method is better than 0.1% except where [DIC] varies faster than 5 μmol/kg per minute. Based on the laboratory and field evaluations, we conclude that this method can provide accurate underway [DIC] measurements at high resolution in most oceanic regions. Schematic illustration of the work flow.

  14. The risk of lead contamination in bone broth diets.

    PubMed

    Monro, J A; Leon, R; Puri, B K

    2013-04-01

    The preparation and consumption of bone broth is being increasingly recommended to patients, for example as part of the gut and psychology syndrome (GAPS) diet for autism, attention-deficit hyperactivity disorder, dyslexia, dyspraxia, depression and schizophrenia, and as part of the paleolithic diet. However, bones are known to sequester the heavy metal lead, contamination with which is widespread throughout the modern environment. Such sequestered lead can then be mobilised from the bones. We therefore hypothesised that bone broth might carry a risk of being contaminated with lead. A small, blinded, controlled study of lead concentrations in three different types of organic chicken broth showed that such broths do indeed contain several times the lead concentration of the water with which the broth is made. In particular, broth made from skin and cartilage taken off the bone once the chicken had been cooked with the bones in situ, and chicken-bone broth, were both found to have markedly high lead concentrations, of 9.5 and 7.01 μg L(-1), respectively (compared with a control value for tap water treated in the same way of 0.89 μg L(-1)). In view of the dangers of lead consumption to the human body, we recommend that doctors and nutritionists take the risk of lead contamination into consideration when advising patients about bone broth diets. PMID:23375414

  15. International experiences in assessing vitamin A status and applying the vitamin A-labeled isotope dilution method.

    PubMed

    Lopez-Teros, Veronica; Chileshe, Justin; Idohou-Dossou, Nicole; Fajarwati, Tetra; Medoua Nama, Gabriel; Newton, Sam; Vinod Kumar, Malavika; Wang, Zhixu; Wasantwisut, Emorn; Hunt, Janet R

    2014-01-01

    Inadequate vitamin A (VA) nutrition continues to be a major problem worldwide, and many interventions being implemented to improve VA status in various populations need to be evaluated. The interpretation of results after an intervention depends greatly on the method selected to assess VA status. To evaluate the effect of an intervention on VA status, researchers in Cameroon, India, Indonesia, Mexico, Senegal and Zambia have used serum retinol as an indicator, and have not always found improvement in response to supplementation. One problem is that homeostatic control of serum retinol may mask positive effects of treatment in that changes in concentration are observed only when status is either moderately to severely depleted or excessive. Because VA is stored mainly in the liver, measurements of hepatic VA stores are the “gold standard” for assessing VA status. Dose response tests such as the relative dose response (RDR) and the modified relative dose response (MRDR), allow a qualitative assessment of VA liver stores. On the other hand, the use of the vitamin A-labeled isotope dilution (VALID) technique, (using 13C or 2H-labeled retinyl acetate) serves as an indirect method to quantitatively estimate total body and liver VA stores. Countries including Cameroon, China, Ghana, Mexico, Thailand and Zambia are now applying the VALID method to sensitively assess changes in VA status during interventions, or to estimate a population’s dietary requirement for VA. Transition to the use of more sensitive biochemical indicators of VA status such as the VALID technique is needed to effectively assess interventions in populations where mild to moderate VA deficiency is more prevalent than severe deficiency. PMID:25537105

  16. Dermal uptake of 18 dilute aqueous chemicals: in vivo disappearance-method measures greatly exceed in vitro-based predictions.

    PubMed

    Bogen, Kenneth T

    2013-07-01

    Average rates of total dermal uptake (Kup ) from short-term (e.g., bathing) contact with dilute aqueous organic chemicals (DAOCs) are typically estimated from steady-state in vitro diffusion-cell measures of chemical permeability (Kp ) through skin into receptor solution. Widely used ("PCR-vitro") methods estimate Kup by applying diffusion theory to increase Kp predictions made by a physico-chemical regression (PCR) model that was fit to a large set of Kp measures. Here, Kup predictions for 18 DAOCs made by three PCR-vitro models (EPA, NIOSH, and MH) were compared to previous in vivo measures obtained by methods unlikely to underestimate Kup . A new PCR model fit to all 18 measures is accurate to within approximately threefold (r = 0.91, p < 10(-5) ), but the PCR-vitro predictions (r > 0.63) all tend to underestimate the Kup measures by mean factors (UF, and p value for testing UF = 1) of 10 (EPA, p < 10(-6) ), 11 (NIOSH, p < 10(-8) ), and 6.2 (MH, p = 0.018). For all three PCR-vitro models, log(UF) correlates negatively with molecular weight (r(2) = 0.31 to 0.84, p = 0.017 to < 10(-6) ) but not with log(vapor pressure) as an additional predictor (p > 0.05), so vapor pressure appears not to explain the significant in vivo/PCR-vitro discrepancy. Until this discrepancy is explained, careful in vivo measures of Kup should be obtained for more chemicals, the expanded in vivo database should be compared to in vitro-based predictions, and in vivo data should be considered in assessing aqueous dermal exposure and its uncertainty. PMID:23051616

  17. Validity of the tritiated thymidine method for estimating bacterial growth rates: measurement of isotope dilution during DNA synthesis

    SciTech Connect

    Pollard, P.C.; Moriarty, D.J.W.

    1984-12-01

    The rate of tritiated thymidine incorporation into DNA was used to estimate bacterial growth rates in aquatic environments. To be accurate, the calculation of growth rates has to include a factor for the dilution of isotope before incorporation. The validity of an isotope dilution analysis to determine this factor was verified in experiments reported here with cultures of a marine bacterium growing in a chemostat. Growth rates calculated from data on chemostat dilution rates and cell density agreed well with rates calculated by tritiated thymidine incorporation into DNA and isotope dilution analysis. With sufficiently high concentrations of exogenous thymidine, de novo synthesis of deoxythymidine monophosphate was inhibited, thereby preventing the endogenous dilution of isoope. The thymidine technique was also shown to be useful for measuring growth rates of mixed suspensions of bacteria growing anaerobically. Thymidine was incorporated into the DNA of a range of marine pseudomonads that were investigated. Three species did not take up thymidine. The common marine cyanobacterium Synechococcus species did not incorporate thymidine into DNA.

  18. New method for caffeine quantification by planar chromatography coupled with electropray ionization mass spectrometry using stable isotope dilution analysis.

    PubMed

    Aranda, Mario; Morlock, Gertrud

    2007-01-01

    A new high-performance thin-layer chromatography/electrospray ionization mass spectrometry (HPTLC/ESI-MS) method for the quantification of caffeine in pharmaceutical and energy drink samples was developed using stable isotope dilution analysis (SIDA). After sample preparation, samples and caffeine standard were applied on silica gel 60 F254 HPTLC plates and over-spotted with caffeine-d3 used for correction of the plunger positioning. After chromatography, densitometric detection was performed by UV absorption at 274 nm. The bands were then eluted by means of a plunger-based extractor into the ESI interface of a single-quadrupole mass spectrometer. For quantification by MS the [M+H]+ ions of caffeine and caffeine-d3 were recorded in the positive ion single ion monitoring (SIM) mode at m/z 195 and 198, respectively. The calibration showed a linear regression with a determination coefficient (R2) of 0.9998. The repeatability (RSD, n=6) in matrix wasmethod accuracy was evaluated by comparing the results obtained by HPTLC/SIDA-ESI-MS with those from the validated HPTLC/UV method. The results for pharmaceutical and energy drink samples were (ng/band) 99.82+/-3.75 and 338.09+/-4.87 by HPTLC/SIDA-ESI-MS and 104.74+/-1.51 and 334.86+/-5.63 by HPTLC/UV. According to the F-test (homogeneity of variances) and the t-test (comparison of means) the two methods show no significant difference. The detection and quantification limits were 75 and 250 microg L-1 (0.75 and 2.5 ng/band), respectively, which were a factor of 13 lower than those established for HPTLC/UV. The positioning error (RSD+/-6%) was calculated by comparing HPTLC/SIDA-ESI-MS with HPTLC/ESI-MS. However, using SIDA the positioning error was nullified. HPTLC/SIDA-ESI-MS was demonstrated to be a

  19. Revisiting Pneumococcal Carriage by Use of Broth Enrichment and PCR Techniques for Enhanced Detection of Carriage and Serotypes▿

    PubMed Central

    Carvalho, Maria da Gloria; Pimenta, Fabiana C.; Jackson, Delois; Roundtree, Alexis; Ahmad, Yusra; Millar, Eugene V.; O'Brien, Katherine L.; Whitney, Cynthia G.; Cohen, Adam L.; Beall, Bernard W.

    2010-01-01

    The measurement of pneumococcal carriage in the nasopharyngeal reservoir is subject to potential confounders that include low-density and multiple-strain colonization. To compare different methodologies, we picked a random sampling of 100 nasopharyngeal specimens recovered from infants less than 2 years of age who were previously assessed for pneumococcal carriage and serotypes by a conventional method that used direct plating from the transport/storage medium (50 specimens were culture negative and 50 specimens were culture positive for pneumococci). We used a broth enrichment approach and a conventional PCR approach (with and without broth enrichment) to determine pneumococcal carriage and serotypes, and the results were compared to the initial conventional culture-based results. Additionally, we used a lytA-targeted real-time PCR for pneumococcal detection. Broth enrichment for both the culture-based and the PCR-based methods enhanced the isolation of pneumococci and detection of serotype diversity, with the most effective serotype deduction method being one that used broth enrichment prior to sequential multiplex PCR. Similarly, we also found that broth enrichment followed by the lytA-specific real-time PCR was the most sensitive for the detection of apparent pneumococcal carriage. The broth enrichment, conventional multiplex PCR, and real-time PCR approaches used in this study were effective in detecting pneumococcal carriage in the 50 specimens that were negative by conventional direct plating from transport medium (range of numbers of positive specimens, 8/50 to 22/50 [16 to 44%]), and the three different serotyping approaches that used broth enrichment increased the number of serotype identifications from the 100 specimens (12 to 29 additional serotype identifications to be positive). A PCR-based approach that employed a broth enrichment step appeared to best enhance the detection of mixed serotypes and low-density pneumococcal carriage. PMID:20220175

  20. Precision of glucose measurements in control sera by isotope dilution/mass spectrometry: proposed definitive method compared with a reference method

    SciTech Connect

    Pelletier, O.; Arratoon, C.

    1987-08-01

    This improved isotope-dilution gas chromatographic/mass spectrometric (GC/MS) method, in which (/sup 13/C)glucose is the internal standard, meets the requirements of a Definitive Method. In a first study with five reconstituted lyophilized sera, a nested analysis of variance of GC/MS values indicated considerable among-vial variation. The CV for 32 measurements per serum ranged from 0.5 to 0.9%. However, concentration and uncertainty values (mmol/L per gram of serum) assigned to one serum by the NBS Definitive Method (7.56 +/- 0.28) were practically identical to those obtained with the proposed method (7.57 +/- 0.20). In the second study, we used twice more (/sup 13/C)glucose diluent to assay four serum pools and two lyophilized sera. The CV ranged from 0.26 to 0.5% for the serum pools and from 0.28 to 0.59% for the lyophilized sera. In comparison, results by the hexokinase/glucose-6-phosphate dehydrogenase reference method agreed within acceptable limits with those by the Definitive Method but tended to be slightly higher (up to 3%) for lyophilized serum samples or slightly lower (up to 2.5%) for serum pools.

  1. Use of a novel radiometric method to assess the inhibitory effect of donepezil on acetylcholinesterase activity in minimally diluted tissue samples

    PubMed Central

    Kikuchi, Tatsuya; Okamura, Toshimitsu; Arai, Takuya; Obata, Takayuki; Fukushi, Kiyoshi; Irie, Toshiaki; Shiraishi, Tetsuya

    2010-01-01

    Background and purpose: Cholinesterase inhibitors have been widely used for the treatment of patients with dementia. Monitoring of the cholinesterase activity in the blood is used as an indicator of the effect of the cholinesterase inhibitors in the brain. The selective measurement of cholinesterase with low tissue dilution is preferred for accurate monitoring; however, the methods have not been established. Here, we investigated the effect of tissue dilution on the action of cholinesterase inhibitors using a novel radiometric method with selective substrates, N-[14C]methylpiperidin-4-yl acetate ([14C]MP4A) and (R)-N-[14C]methylpiperidin-3-yl butyrate ([14C]MP3B_R), for AChE and butyrylcholinesterase (BChE) respectively. Experimental approach: We investigated the kinetics of hydrolysis of [14C]-MP4A and [14C]-MP3B_R by cholinesterases, and evaluated the selectivity of [14C]MP4A and [14C]MP3B_R for human AChE and BChE, respectively, compared with traditional substrates. Then, IC50 values of cholinesterase inhibitors in minimally diluted and highly diluted tissues were measured with [14C]MP4A and [14C]MP3B_R. Key results: AChE and BChE activities were selectively measured as the first-order hydrolysis rates of [14C]-MP4A and [14C]MP3B_R respectively. The AChE selectivity of [14C]MP4A was an order of magnitude higher than traditional substrates used for the AChE assay. The IC50 values of specific AChE and BChE inhibitors, donepezil and ethopropazine, in 1.2-fold diluted human whole blood were much higher than those in 120-fold diluted blood. In addition, the IC50 values of donepezil in monkey brain were dramatically decreased as the tissue was diluted. Conclusions and implications: This method would effectively monitor the activity of cholinesterase inhibitors used for therapeutics, pesticides and chemical warfare agents. PMID:20401964

  2. Steady-state shear characteristics of Aspergillus niger broths

    SciTech Connect

    Svihla, C.K.; Dronawat, S.N.; Hanley, T.R.

    1995-12-31

    It can be difficult to obtain reliable rheological data for filamentous fermentation broths using conventional instruments. One common approach is to measure the torque drawn by an impeller rotating in the suspension. Many previous workers have assumed that the applicable shear rate in such a device is related to the impeller speed by a fluid-independent constant determined by calibration with Newtonian and non-Newtonian fluids. The rheology of Aspergillus niger broths have been characterized using the impeller viscometer approach. The changes in the broth rheology were measured, and used to interpret the growth of biomass and the evolution of the microorganism morphology.

  3. Modified Lombard-Dowell broth as a general growth medium.

    PubMed Central

    Jessee, M T; Robinson, P J

    1977-01-01

    A new liquid medium (modified Lombard-Dowell broth) was inoculated with stock culture strains of aerobic and anaerobic bacteria and compared with prereduced chopped-meat glucose inoculated with the same anaerobes. Both broths were subcultured at 48 and 72 h to aerobic and anaerobic blood agar plates, and the numbers of colonies were compared after 48-h incubation of the agar plates. This was repeated with mixed cultures of both aerobes and anaerobes. For a period of 11 months all specimens received for anaerobic-aerobic culture were inoculated into prereduced chopped-meat glucose and modified Lombard-Dowell broth plus the appropriate plate medium. Growth from subcultures was compared with primary plate isolates. Chopped-meat glucose and modified Lombard-Dowell broth isolates agreed, with the exception of one, Fusobacterium necrophorum, that did not grow in chopped-meat glucose. PMID:925150

  4. Automatic tracer-dilution method used for stage-discharge ratings and streamflow hydrographs on small Iowa streams

    USGS Publications Warehouse

    Soenksen, P.J.

    1990-01-01

    Tracer-dilution discharge measurements were made during 14 flow periods at six stations from 1986 through 1988 water years. Ratings were developed at three stations with the aid of these measurements. A loop rating was identified at one station during rapidly-changing flow conditions. Incomplete mixing and dye loss to sediment apparently were problems at some stations. Stage hydrographs were recorded for 38 flows at seven stations. Limited data on background fluorescence during high flows were also obtained.

  5. Bioscreening and expression of a camel anti-CTGF VHH nanobody and its renaturation by a novel dialysis-dilution method.

    PubMed

    Xue, Xiulei; Fan, Xiaobo; Qu, Qingrong; Wu, Guoqiu

    2016-12-01

    The variable regions of the camel heavy chain antibody, also known as nanobody is the smallest antibody with antigen-binding efficiency. CTGF is considered important during extracellular matrix deposition which was involved in the pathogenesis of fibrosis related diseases. There are several anti-CTGF-C nanobody drugs under developing in pharmacy. In this study, we described the screening of a novel anti-CTGF-C nanobody from the peripheral blood of immunized camel by phage display. The screened nanobody was further expressed and purified from E. coli cells. A sophisticated dialysis-dilution method was designed for the in vitro refolding of the nanobody. The results showed that the expressed nanobody was consisted of 135 amino acid and mainly expressed as inclusion body in E. coli cells. The dialysis-dilution method was very effective and the recovery rate of the renaturation was more than 80 %. The ELISA result suggested the nanobody had been well refolded showing a superior CTGF binding activity to the commercial mouse anti-CTGF-C mAb. In conclusion, the anti-CTGF-C nonobody had been successfully screened by phage display. The dialysis-dilution refolding method was very effective and the recovery rate reached over 80 %. PMID:27620736

  6. Cross-flow membrane microfiltration of a bacteriol fermentation broth.

    PubMed

    Nagata, N; Herouvis, K J; Dziewulski, D M; Belfort, G

    1989-08-01

    Although cross-flow membrane filtration is a very attractive option for harvesting cells and recovering enzymes from cell homogenates, the process is not without its problems. Foremost of these is the deposit of dissolved and suspended solutes onto the membrane surface during operation. The formation of these dense and sometimes compressive sublayers (often called cakes) offers additional resistance to axial and permeate flows and often affects the retention characteristics of the process. In view of the complex nature of the sublayer formation process and its sensitivity to cross-flow velocity, this investigation was undertaken to determine the main factors responsible for the decline in performance during the harvesting of B. polymyxa broth by membrane microfiltration. System parameters varied include axial flow rate, concentration of cells, proteins and other components in the feed, membrane materials (ceramic, polypropylene, and stainless steel), and cleaning methods. To help explain the observed results, a new mass transport model-the solids flux model-based on the assumptions that back migration of particles from the sublayer or membrane surface is negligible and that particles that reach the solid-solution interface attach (stick) completely, is tested. Using a variety of diagnostic methods, magnesium ammonium phosphate precipitate is formed during steam sterilization of the medium and is implicated as the major foulant in this study. PMID:18588126

  7. Thermodynamics of Dilute Solutions.

    ERIC Educational Resources Information Center

    Jancso, Gabor; Fenby, David V.

    1983-01-01

    Discusses principles and definitions related to the thermodynamics of dilute solutions. Topics considered include dilute solution, Gibbs-Duhem equation, reference systems (pure gases and gaseous mixtures, liquid mixtures, dilute solutions), real dilute solutions (focusing on solute and solvent), terminology, standard states, and reference systems.…

  8. Binding of Todd-Hewitt broth antigens by Streptococcus mutans.

    PubMed Central

    Stinson, M W; Jones, C A

    1983-01-01

    Streptococcus mutans 10449, grown in chemically defined culture medium, was tested for its ability to bind 3H-labeled Todd-Hewitt broth components (greater than 12,000 Mr). Maximum adsorption of radioactivity occurred within 5 min at room temperature, and cell-bound material was not completely removed by extended washing with buffer. Heat-killed, arsenate-inhibited, and viable bacteria bound similar quantities. Only 0.09% of the radioactivity in the preparation of high Mr Todd-Hewitt broth components was removed by absorption with excess numbers of S. mutans 10449 cells. Binding followed saturation kinetics and was competitively inhibited by unlabeled medium components, both the dialyzable and nondialyzable fractions. Other oral streptococci were also found to bind these complex medium components. Rabbit antiserum elicited to the high-molecular-weight Todd-Hewitt broth components reacted with monkey cardiac muscle and with S. mutans coated with medium components. Absorption of the anti-Todd-Hewitt broth serum with homogenized heart removed antibodies that reacted with Todd-Hewitt broth-coated S. mutans. Therefore, the tissue-specific antigens of this beef heart infusion medium that adsorb to S. mutans can interfere with the detection and characterization of antigens shared by these bacteria and animal tissues. Images PMID:6852915

  9. Evaluation of TA10 Broth for Recovery of Heat- and Freeze-Injured Salmonella from Beef

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Bacteriological Analytical Manual (BAM) Salmonella pre-enrichment broth (lactose [LAC] broth), buffered peptone water (BPW), and universal preenrichment (UP) broth were compared with TA10 broth, developed in our laboratory, for recovery of heat- and freeze-injured Salmonella (55ºC for 2-20 min a...

  10. HPLC-ELSD determination of kanamycin B in the presence of kanamycin A in fermentation broth.

    PubMed

    Zhang, Yong; He, Hui-Min; Zhang, Jin; Liu, Feng-Jiao; Li, Chao; Wang, Bing-Wu; Qiao, Ren-Zhong

    2015-03-01

    A novel method for the direct determination of kanamycin B in the presence of kanamycin A in fermentation broth using high performance liquid chromatography with evaporative light scattering detector (HPLC-ELSD) was developed. An Agilent Technologies C18 column was utilized, evaporation temperature of 40°C and nitrogen pressure of 3.5 bar, the optimized mobile phase was water-acetonitrile (65:35, v/v), containing 11.6 mm heptafluorobutyric acid (isocratic elution with flow rate of 0.5 mL/min) with the gain 11. Kanamycin B was eluted at 5.6 min with an asymmetry factor of 1.827. The method showed good linearity over the concentration range of 0.05 to 0.80 mg/mL for the kanamycin B (r(2) = 0.9987). The intra-day and inter-day coefficients of variation obtained from kanamycin B were less than 4.3%. Mean recovery of kanamycin B from spiked fermentation broth was 95%. The developed method was applied to the determination of kanamycin B without any interference from other constituents in the fermentation broth. This method offers simple, rapid and quantitative detection of kanamycin B. PMID:25042110

  11. Direct measurement of the yield stress of filamentous fermentation broths with the rotating vane technique.

    PubMed

    Leong-Poi, L; Allen, D G

    1992-07-01

    The existence of a yield stress in filamentous fermentation broths has important transport phenomena implications in the design and operation of bioreactors. In this study, the constant shear rate vane method was assessed for directly measuring the yield stress of filamentous Aspergillus niger fermentation broths, as well as model fluids (ketchup, yogurt, and pulp suspensions). The method involved rotating 4-, 6-, and 8-bladed vanes (7.2 cm < or = height < or = 15 cm; 4.0 cm < or = dia. < or= 6 cm) at speeds of 0.01 to 0.64 rpm in the fluid and plotting the torque as a function of time. Based on visual observations, the consistency of the results with vane type and speed and comparison with previous work on nonbiological samples, it was concluded that the method is an effective and consistent technique for yield stress measurements on filamentous fermentation broths. Based on comparisons with concentric cylinder viscometer results, it was also concluded that the value determined via the vane method was a "static" yield stress (values of up to 28 Pa) which was much greater than the extrapolated (or "dynamic") yield stress determined via the concentric cylinder viscometer. PMID:18601131

  12. Superparamagnetic poly(methyl methacrylate) beads for nattokinase purification from fermentation broth.

    PubMed

    Yang, Chengli; Xing, Jianmin; Guan, Yueping; Liu, Huizhou

    2006-09-01

    An effective method for purification of nattokinase from fermentation broth using magnetic poly(methyl methacrylate) (PMMA) beads immobilized with p-aminobenzamidine was proposed in this study. Firstly, magnetic PMMA beads with a narrow size distribution were prepared by spraying suspension polymerization. Then, they were highly functionalized via transesterification reaction with polyethylene glycol. The surface hydroxyl-modified magnetic beads obtained were further modified with chloroethylamine to transfer the surface amino-modified magnetic functional beads. The morphology and surface functionality of the magnetic beads were examined by scanning electron microscopy and Fourier transform infrared. An affinity ligand, p-aminobenzamidine was covalently immobilized to the amino-modified magnetic beads by the glutaraldehyde method for nattokinase purification directly from the fermentation broth. The purification factor and the recovery of the enzyme activity were found to be 8.7 and 85%, respectively. The purification of nattokinase from fermentation broth by magnetic beads only took 40 min, which shows a very fast purification of nattokinase compared to traditional purification methods. PMID:16736086

  13. Application of electrodialysis to glycerate recovery from a glycerol containing model solution and culture broth.

    PubMed

    Habe, Hiroshi; Fukuoka, Tokuma; Kitamoto, Dai; Sakaki, Keiji

    2009-04-01

    Glyceric acid is produced by the conversion of glycerol via bioprocesses. The glycerate recovery from model solutions and from real culture broth was demonstrated by a desalting electrodialysis (ED) method. The addition of several impurities in glycerate model solutions, such as polypepton or yeast extract, did not have significant adverse effects on the whole ED process, and more than 93% of the glycerol added in the model solutions (50-150 g/l) was excluded. Using culture broth of Acetobacter tropicalis containing 14.6 g/l D-glycerate, the D-glycerate recovery and the energy consumption were 99.4% and 0.24 kWh/kg, respectively. PMID:19332303

  14. Two-stage electrodialytic concentration of glyceric acid from fermentation broth.

    PubMed

    Habe, Hiroshi; Shimada, Yuko; Fukuoka, Tokuma; Kitamoto, Dai; Itagaki, Masayuki; Watanabe, Kunihiko; Yanagishita, Hiroshi; Sakaki, Keiji

    2010-12-01

    The aim of this research was the application of a two-stage electrodialysis (ED) method for glyceric acid (GA) recovery from fermentation broth. First, by desalting ED, glycerate solutions (counterpart is Na+) were concentrated using ion-exchange membranes, and the glycerate recovery and energy consumption became more efficient with increasing the initial glycerate concentration (30 to 130 g/l). Second, by water-splitting ED, the concentrated glycerate was electroconverted to GA using bipolar membranes. Using a culture broth of Acetobacter tropicalis containing 68.6 g/l of D-glycerate, a final D-GA concentration of 116 g/l was obtained following the two-stage ED process. The total energy consumption for the D-glycerate concentration and its electroconversion to D-GA was approximately 0.92 kWh per 1 kg of D-GA. PMID:20674487

  15. Slide coagglutination for Salmonella typhi antigens in broths inoculated with feces from typhoid fever patients.

    PubMed

    Rockhill, R C; Rumans, L W; Lesmana, M

    1981-12-01

    Salmonella typhi antigens D, Vi and d were readily detected, by slide coagglutination, in mannitol selenite (MSB) and dulcitol selenite (DSB), Salmonella enrichment broths 4 hours after inoculation with feces from 60 patients with bacteriologically confirmed typhoid fever. Positive coagglutination also occurred using MSB and DSB inoculated with fecal specimens obtained from 16 patients from whom S. typhi was not cultured. Twelve of these later seroconverted to Salmonella O antigen. None of the MSB or DSB inoculated with feces from 50 healthy control subjects, gave a positive coagglutination test. The coagglutination method appears to have potential as a rapid test for the detection of antigens of S. typhi in MSB and DSB broths inoculated with feces from patients with suspected typhoid fever. PMID:7344101

  16. Separation of salvianic acid A from the fermentation broth of engineered Escherichia coli using macroporous resins.

    PubMed

    Bai, Chen-Long; Zhao, Guang-Rong

    2015-08-01

    Salvianic acid A (also known as danshensu) is a plant-derived polyphenolic acid, and has a variety of physiological and pharmacological activities. Our laboratory previously constructed an unprecedented artificial biosynthetic pathway in Escherichia coli and established the fermentation process to produce salvianic acid A. Here, we developed an efficient method for separating salvianic acid A from the fermentation broth of engineered Escherichia coli by macroporous resins. Among ten tested macroporous resins, the static and dynamic adsorption/desorption experiments demonstrated that X5 resin was the best to separate salvianic acid A from fermentation broth. Other parameters during static and dynamic procedures were also investigated. Under the optimum separation conditions, the average adsorption capacity of SAA were 10.66±0.54 mg/g dry resin and the desorption ratio was 85.6±4.1%. The purity and recovery yield of salvianic acid A in the final dry product were 90.2±1.5 and 81.5±2.3%, respectively. The results show that adsorption separation with macroporous resin X5 was an efficient method to prepare salvianic acid A from fermentation broth. This work will benefit the development and application of plant-derived salvianic acid A and its derivatives. PMID:26097085

  17. First Comprehensive Evaluation of the M.I.C. Evaluator Device Compared to Etest and CLSI Broth Microdilution for MIC Testing of Aerobic Gram-Positive and Gram-Negative Bacterial Species

    PubMed Central

    Turnbull, L.; Brosnikoff, C.; Cloke, J.

    2012-01-01

    The M.I.C. Evaluator strip (Thermo Fisher Scientific, Basingstoke, United Kingdom) uses a methodology similar to that of Etest. In this first assessment of the M.I.C. Evaluator device, 409 strains of aerobic Gram-positive bacteria (staphylococci, streptococci, and enterococci) and 325 strains of Enterobacteriaceae, Pseudomonas species, and Acinetobacter species were tested by M.I.C. Evaluator strip, Etest, and broth microdilution as a reference standard. The Gram-positive bacteria included staphylococci (methicillin-resistant Staphylococcus aureus, methicillin-susceptible S. aureus, and coagulase-negative staphylococci), Streptococcus pneumoniae, beta-hemolytic streptococci and viridians group strains, vancomycin-resistant enterococci, and other enterococci. The Gram-negative bacteria included 250 strains of 60 Enterobacteriaceae species plus 50 Pseudomonas and 25 Acinetobacter species. A total of 14 antimicrobial agents (depending on the species) were included. The same methodology and reading format were used for M.I.C. Evaluator strips and Etest. Broth microdilution methodology was performed according to CLSI document M07-A8. For the clinical strains, >95% of results were plus or minus one doubling dilution for all species. There were fewer than 5% minor errors, fewer than 3% major errors, and fewer than 1% very major errors. M.I.C. Evaluator strips and Etest often reported higher MICs than the reference broth microdilution method. The M.I.C. Evaluator strips provided results comparable to those of the predicate Etest device and are of value for the accurate testing of MICs for these important pathogens. PMID:22238441

  18. Evaluation of a Scanner-Assisted Colorimetric MIC Method for Susceptibility Testing of Gram-Negative Fermentative Bacteria

    PubMed Central

    Rahman, Mokhlasur; Kühn, Inger; Rahman, Motiur; Olsson-Liljequist, Barbro; Möllby, Roland

    2004-01-01

    We describe the ScanMIC method, a colorimetric MIC method for susceptibility testing of gram-negative fermentative bacteria. The method is a slight modification of the National Committee for Clinical Laboratory Standards (NCCLS) recommended broth microdilution method that uses a redox indicator 2,3,5-triphenyltetrazolium chloride (TTC) to enhance the estimate of bacterial growth inhibition in a microplate and a flatbed scanner to capture the microplate image. In-house software was developed to transform the microplate image into numerical values based on the amount of bacterial growth and to generate the MICs automatically. The choice of indicator was based on its low toxicity and ease of reading by scanner. We compared the ScanMIC method to the NCCLS recommended broth microdilution method with 197 coliform strains against seven antibacterial agents. The interpretative categorical agreement was obtained in 92.4% of the assays, and the agreement for MIC differences (within ±1 log2 dilution) was obtained in 96% for ScanMIC versus broth microdilution and 97% for a two-step incubation colorimetric broth microdilution versus the broth microdilution method. The method was found to be labor-saving, not to require any initial investment, and to show reliable results. Thus, the ScanMIC method could be useful for epidemiological surveys that include susceptibility testing of bacteria. PMID:15066837

  19. Can too many copies spoil the broth?

    PubMed Central

    2013-01-01

    The success of Pichia pastoris as a heterologous expression system lies predominantly in the impressive yields that can be achieved due to high volumetric productivity. However, low specific productivity still inhibits the potential success of this platform. Multi-(gene) copy clones are potentially a quick and convenient method to increase recombinant protein titer, yet they are not without their pitfalls. It has been more than twenty years since the first reported use of multi-copy clones and it is still an active area of research to find the fastest and most efficient method for generating these strains. It has also become apparent that there is not always a linear correlation between copy number and protein titer, leading to in-depth investigations into how to minimize the negative impact of secretory stress and achieve clonal stability. PMID:24354594

  20. Serial Dilution Simulation Lab

    ERIC Educational Resources Information Center

    Keler, Cynthia; Balutis, Tabitha; Bergen, Kim; Laudenslager, Bryanna; Rubino, Deanna

    2010-01-01

    Serial dilution is often a difficult concept for students to understand. In this short dry lab exercise, students perform serial dilutions using seed beads. This exercise helps students gain skill at performing dilutions without using reagents, bacterial cultures, or viral cultures, while being able to visualize the process.

  1. Two high performance liquid chromatographic methods for the determination of alpha-tocopherol in serum compared to isotope dilution-gas chromatography-mass spectrometry.

    PubMed

    Kock, R; Seitz, S; Delvoux, B; Greiling, H

    1997-05-01

    Two high performance liquid chromatographic methods (HPLC) with isocratic reversed-phase separation are presented for the determination of alpha-tocopherol (vitamin E) in serum. In the first method alpha-tocopherol acetate is used as internal standard, detection of absorbance is performed at 284 nm. In the second method tocol is used as internal standard, detection of fluorescence is performed with an excitation wavelength of 292 nm and emission wavelength of 325 nm. Both methods require a liquid-liquid extraction as sample preparation. The results of both HPLC methods have been tested by method comparison for n = 25 serum samples versus an isotope dilution-gas chromatography-mass spectrometry (ID-GC-MS) method using alpha-tocopherol-d6 as internal standard. The imprecision within-run was lower than 2.5% for the UV method and lower than 1% for the fluorescence method for both standards and serum pools. The between-run imprecision, obtained for serum pools, was below 5% for the UV method and not higher than 1.5% for the fluorescence method and not higher 1.8% for the ID-GC-MS. Recovery experiments performed by spiking pool sera with alpha-tocopherol showed recoveries between 98.5% and 100.6% for all methods studied. The result of the method comparison was a coefficient of correlation of r = 0.998 for the HPLC method with fluorescence detection to the ID-GC-MS reference method and a coefficient of correlation of r = 0.981 for the HPLC method with UV detection to the ID-GC-MS reference method. Both methods presented are useful for the analysis of alpha-tocopherol in patient samples. If detection of fluorescence is used, imprecision and inaccuracy of the HPLC method are comparable to the ID-GC-MS chosen as reference method. PMID:9189742

  2. Artifacts in dilution pharmacokinetic models caused by adherent bacteria.

    PubMed Central

    Haag, R; Lexa, P; Werkhäuser, I

    1986-01-01

    Liquid cultures of a Pseudomonas aeruginosa strain in Mueller-Hinton broth diluted at rates higher than the bacterial growth rate showed the expected decrease in CFU only for 1 to 2 h. Later the CFU started to increase. This phenomenon can be explained by a hypothesis that assumes that the bacteria multiply in two different compartments. From the first compartment, which comprises bacteria homogeneously distributed in the broth, cells are eliminated at a rate that is dependent on the dilution and growth rates. Concomitantly, the second compartment is formed as a nondilutable adherent population on the surface of the culture vessel. Eventually, only cells stemming from that population appeared in the medium and were subsequently diluted. This hypothesis can be described mathematically by a linear combination of two exponential functions. The calculated values fit the experimental data well. Because similar CFU versus time curves were also found with other strains, care should be taken in interpreting results of experiments performed in liquid cultures and evaluated in terms of CFU. One should bear in mind that within a liquid culture an adherent population may exist, which differs in size according to selective influences (dilution, addition of antibiotics, etc.). This may give rise to artificial and unexpected results. PMID:3089140

  3. Cross-correlation focus method with an electrostatic sensor array for local particle velocity measurement in dilute gas-solid two-phase flow

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Zhang, Jingyu; Gao, Wenbin; Ding, Hongbing; Wu, Weiping

    2015-11-01

    The gas-solid two-phase flow has been widely applied in the power, chemical and metallurgical industries. It is of great significance in the research of gas-solid two-phase flow to measure particle velocity at different locations in the pipeline. Thus, an electrostatic sensor array comprising eight arc-shaped electrodes was designed. The relationship between the cross-correlation (CC) velocity and the distribution of particle velocity, charge density and electrode spatial sensitivity was analysed. Then the CC sensitivity and its calculation method were proposed. According to the distribution of CC sensitivity, it was found that, between different electrode pairs, it had different focus areas. The CC focus method was proposed for particle velocity measurement at different locations and validated by a belt-style electrostatic induction experiment facility. Finally, the particle velocities at different locations with different flow conditions were measured to research the particle velocity distribution in a dilute horizontal pneumatic conveying pipeline.

  4. Standard dilution analysis.

    PubMed

    Jones, Willis B; Donati, George L; Calloway, Clifton P; Jones, Bradley T

    2015-02-17

    Standard dilution analysis (SDA) is a novel calibration method that may be applied to most instrumental techniques that will accept liquid samples and are capable of monitoring two wavelengths simultaneously. It combines the traditional methods of standard additions and internal standards. Therefore, it simultaneously corrects for matrix effects and for fluctuations due to changes in sample size, orientation, or instrumental parameters. SDA requires only 200 s per sample with inductively coupled plasma optical emission spectrometry (ICP OES). Neither the preparation of a series of standard solutions nor the construction of a universal calibration graph is required. The analysis is performed by combining two solutions in a single container: the first containing 50% sample and 50% standard mixture; the second containing 50% sample and 50% solvent. Data are collected in real time as the first solution is diluted by the second one. The results are used to prepare a plot of the analyte-to-internal standard signal ratio on the y-axis versus the inverse of the internal standard concentration on the x-axis. The analyte concentration in the sample is determined from the ratio of the slope and intercept of that plot. The method has been applied to the determination of FD&C dye Blue No. 1 in mouthwash by molecular absorption spectrometry and to the determination of eight metals in mouthwash, wine, cola, nitric acid, and water by ICP OES. Both the accuracy and precision for SDA are better than those observed for the external calibration, standard additions, and internal standard methods using ICP OES. PMID:25599250

  5. Green synthesis of gold nanoparticles using Cinnamomum zeylanicum leaf broth

    NASA Astrophysics Data System (ADS)

    Smitha, S. L.; Philip, Daizy; Gopchandran, K. G.

    2009-10-01

    Development of biologically inspired experimental processes for the synthesis of nanoparticles is an important branch of nanotechnology. The synthesis of gold nanoparticles using Cinnamomum zeylanicum leaf broth as the reducing agent is reported. The morphology of the particles formed consists of a mixture of gold nanoprisms and spheres with fcc (1 1 1) structure of gold. At lower concentrations of the extract, formation of prism shaped Au particles dominates, while at higher concentrations almost spherical particles alone are observed. Good crystallinity of the nanoparticles with fcc phase is evident from XRD patterns, clear lattice fringes in the high resolution TEM image and bright circular rings in the SAED pattern. Au nanoparticles grown are observed to be photoluminescent and the intensity of photoemission is found to increase with increase in leaf broth concentration. The ability to modulate the shape of nanoparticles as observed in this study for gold nanoparticles opens up the exciting possibility of developing further synthetic routes employing ecofriendly sources.

  6. Susceptibility testing with the sensititer breakpoint broth microdilution system.

    PubMed

    Doern, G V; Dascal, A; Keville, M

    1985-05-01

    The antimicrobial susceptibility profiles of a total of 318 aerobic and facultatively anaerobic bacteria (255 gram-negative bacilli and 63 gram-positive cocci) were determined, using a new commercially available breakpoint broth microdilution procedure (Sensititer Breakpoint System (SBS), Gibco Diagnostics, Inc., Madison, WI) that categorizes test results in the form of susceptibility categories: susceptible, intermediate, and resistant. Results obtained with the SBS were compared with those achieved with a standardized disk diffusion procedure. Among a total of 4,414 organism-antimicrobic comparisons, concordance between the results of the SBS and the disk diffusion procedure was observed in 3,888 cases (88.1%). Four hundred twenty-three (9.6%) minor discrepancies, 45 (1.0%) major discrepancies, and 58 (1.3%) very major discrepancies were noted. Arbitration of major and very major discrepancies with a full-range minimum inhibitory concentration (MIC) procedure confirmed the results of the SBS in 53.4% of cases. A single organism-antimicrobial combination, the nonenterococcal streptococci tested against the aminoglycosides, yielded a significant number of very major errors which were arbitrated in favor of the disk diffusion result. These errors were probably due to poor growth of the test organism in the broth medium used for performing the SBS test (i.e., cation-supplemented Mueller-Hinton broth). With this exception, the SBS was found to be at least as accurate as the standardized disk diffusion procedure. PMID:3922668

  7. Microfluidic serial dilution ladder.

    PubMed

    Ahrar, Siavash; Hwang, Michelle; Duncan, Philip N; Hui, Elliot E

    2014-01-01

    Serial dilution is a fundamental procedure that is common to a large number of laboratory protocols. Automation of serial dilution is thus a valuable component for lab-on-a-chip systems. While a handful of different microfluidic strategies for serial dilution have been reported, approaches based on continuous flow mixing inherently consume larger amounts of sample volume and chip real estate. We employ valve-driven circulatory mixing to address these issues and also introduce a novel device structure to store each stage of the dilution process. The dilution strategy is based on sequentially mixing the rungs of a ladder structure. We demonstrate a 7-stage series of 1 : 1 dilutions with R(2) equal to 0.995 in an active device area of 1 cm(2). PMID:24231765

  8. Comparison of two tracer gas dilution methods for the determination of clothing ventilation and of vapour resistance.

    PubMed

    Havenith, George; Zhang, Ping; Hatcher, Kent; Daanen, Hein

    2010-04-01

    Clothing microclimate ventilation is an important parameter in climatic stress and in contaminated environments. The two main methods for its determination (Crockford et al. (CR) 1972 and Lotens and Havenith (LH) 1988) were, after further development, compared in terms of reproducibility, validity and usability. Both methods were shown to have a good sensitivity and reproducibility (with average coefficients of variation 1.5-2.3% for the method alone and up to 7% for method and clothing/movement effects combined). They produced values very close to calibration values in forced ventilation tests (r = 0.988). Weak points for the CR method were the limits in the time constant of the measurement apparatus, causing an upper limit to the ventilation that can be reliably measured (around 800 l/min) and the method of measuring clothing microclimate volume. The original 'vacuum oversuit' (CR) method was cumbersome and prone to large errors. Alternative methods of measuring clothing microclimate volume (whole body scanner or manual circumference measurements) were shown to produce good results. For the LH method, the distribution of the tracer gas over the whole skin surface became a problem factor at very high ventilations (above 1000 l/min). As all methods use tracer gases (O(2), Ar, CO(2), SF(6)) with diffusivities smaller than that of water vapour, this potentially creates a problem in the calculation of vapour resistance from the ventilation values in the region where the emphasis of vapour transfer moves from diffusion to convection. In most real-life situations, where body and air movement are present, a correction is not however required because the error remains below 10%. STATEMENT OF RELEVANCE: Clothing ventilation indicates heat loss potential as well as risk of pollutants entering the clothing. Two main methods for its determination are compared and validated, identifying a number of issues. An in-depth analysis is given of the advantages and disadvantages of

  9. Validation of an isotope dilution gas chromatography-mass spectrometry method for combined analysis of oxysterols and oxyphytosterols in serum samples.

    PubMed

    Schött, Hans-Frieder; Lütjohann, Dieter

    2015-07-01

    We describe the validation of a method for the analysis of oxysterols, i.e. oxycholesterols and oxyphytosterols, in human serum using gas chromatography-mass spectrometry selected ion monitoring (GC-MS-SIM). Concentrations of 7α- and 7β-hydroxy-, and 7oxo-cholesterol, -campesterol, and -sitosterol as well as 4β-hydroxycholesterol and side-chain oxygenated 24S-, 25-, and 27-hydroxycholesterol were determined by isotope dilution methodology. After saponification at room temperature the oxysterols were extracted, separated from their substrates, cholesterol, campesterol, and sitosterol, by solid phase extraction, and subsequently derivatised to their corresponding trimethylsilyl-ethers prior to GC-MS-SIM. In order to prevent artificial autoxidation butylated hydroxytoluene and ethylenediaminetetraacetic acid were added. The validation of the method was performed according to the International Conference on Harmonisation guidance, including limits of detection and quantification, ranges, recovery and precision. Due to improved instrumental settings and work-up procedure, limits of detection and quantification ranged between 8.0-202.0pg/mL and 28.0-674pg/mL, respectively. Recovery data in five calibration points varied between 91.9% and 116.8% and in serum samples between 93.1% and 118.1%. The mean coefficient of variation (CV) for the recovery of all compounds was <10%. Well satisfying CVs for within-day precision (2.1-10.8%) and for between-day precision (2.3-12.1%) were obtained. More than 20 samples could be processed in a single routine day and test series of about 300 samples can be realised without impairment of the validation parameters during a sequence. Comparison of oxysterol and oxyphytosterol content in serum and plasma revealed no difference. A fully validated isotope dilution methodology for the quantification of oxycholesterols and oxyphytosterols from human serum or plasma is presented. PMID:25701095

  10. Multidrug-Resistant Candida auris Misidentified as Candida haemulonii: Characterization by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry and DNA Sequencing and Its Antifungal Susceptibility Profile Variability by Vitek 2, CLSI Broth Microdilution, and Etest Method.

    PubMed

    Kathuria, Shallu; Singh, Pradeep K; Sharma, Cheshta; Prakash, Anupam; Masih, Aradhana; Kumar, Anil; Meis, Jacques F; Chowdhary, Anuradha

    2015-06-01

    Candida auris is a multidrug-resistant yeast that causes a wide spectrum of infections, especially in intensive care settings. We investigated C. auris prevalence among 102 clinical isolates previously identified as Candida haemulonii or Candida famata by the Vitek 2 system. Internal transcribed spacer region (ITS) sequencing confirmed 88.2% of the isolates as C. auris, and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) easily separated all related species, viz., C. auris (n = 90), C. haemulonii (n = 6), C. haemulonii var. vulnera (n = 1), and Candida duobushaemulonii (n = 5). The in vitro antifungal susceptibility was determined using CLSI broth microdilution (CLSI-BMD), the Vitek 2 antifungal susceptibility test, and the Etest method. C. auris isolates revealed uniformly elevated fluconazole MICs (MIC50, 64 μg/ml), and an alarming percentage of isolates (37%) exhibited elevated caspofungin MICs by CLSI-BMD. Notably, 34% of C. auris isolates had coexisting elevated MICs (≥2 μg/ml) for both fluconazole and voriconazole, and 10% of the isolates had elevated coexisting MICs (≥2 μg/ml) to two additional azoles, i.e., posaconazole and isavuconazole. In contrast to reduced amphotericin B MICs by CLSI-BMD (MIC50, 1 μg/ml) for C. auris, elevated MICs were noted by Vitek 2 (MIC50, 8 μg/ml), which were statistically significant. Candida auris remains an unnoticed pathogen in routine microbiology laboratories, as 90% of the isolates characterized by commercial identification systems are misidentified as C. haemulonii. MALDI-TOF MS proved to be a more robust diagnostic technique for rapid identification of C. auris. Considering that misleading elevated MICs of amphotericin B by the Vitek AST-YS07 card may lead to the selection of inappropriate therapy, a cautionary approach is recommended for laboratories relying on commercial systems for identification and antifungal susceptibility testing of rare yeasts. PMID:25809970

  11. Multidrug-Resistant Candida auris Misidentified as Candida haemulonii: Characterization by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry and DNA Sequencing and Its Antifungal Susceptibility Profile Variability by Vitek 2, CLSI Broth Microdilution, and Etest Method

    PubMed Central

    Kathuria, Shallu; Singh, Pradeep K.; Sharma, Cheshta; Prakash, Anupam; Masih, Aradhana; Kumar, Anil

    2015-01-01

    Candida auris is a multidrug-resistant yeast that causes a wide spectrum of infections, especially in intensive care settings. We investigated C. auris prevalence among 102 clinical isolates previously identified as Candida haemulonii or Candida famata by the Vitek 2 system. Internal transcribed spacer region (ITS) sequencing confirmed 88.2% of the isolates as C. auris, and matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) easily separated all related species, viz., C. auris (n = 90), C. haemulonii (n = 6), C. haemulonii var. vulnera (n = 1), and Candida duobushaemulonii (n = 5). The in vitro antifungal susceptibility was determined using CLSI broth microdilution (CLSI-BMD), the Vitek 2 antifungal susceptibility test, and the Etest method. C. auris isolates revealed uniformly elevated fluconazole MICs (MIC50, 64 μg/ml), and an alarming percentage of isolates (37%) exhibited elevated caspofungin MICs by CLSI-BMD. Notably, 34% of C. auris isolates had coexisting elevated MICs (≥2 μg/ml) for both fluconazole and voriconazole, and 10% of the isolates had elevated coexisting MICs (≥2 μg/ml) to two additional azoles, i.e., posaconazole and isavuconazole. In contrast to reduced amphotericin B MICs by CLSI-BMD (MIC50, 1 μg/ml) for C. auris, elevated MICs were noted by Vitek 2 (MIC50, 8 μg/ml), which were statistically significant. Candida auris remains an unnoticed pathogen in routine microbiology laboratories, as 90% of the isolates characterized by commercial identification systems are misidentified as C. haemulonii. MALDI-TOF MS proved to be a more robust diagnostic technique for rapid identification of C. auris. Considering that misleading elevated MICs of amphotericin B by the Vitek AST-YS07 card may lead to the selection of inappropriate therapy, a cautionary approach is recommended for laboratories relying on commercial systems for identification and antifungal susceptibility testing of rare yeasts. PMID:25809970

  12. Comparative evaluation of supplemented peptone broth with sodium polyanetholesulfonate and trypticase soy broth with sodium amylosulfate for detection of septicemia.

    PubMed Central

    Tenney, J H; Reller, L B; Wang, W L; Cox, R L; Mirrett, S

    1982-01-01

    We compared the yield and speed of detection of clinically important microorganisms from 10,156 paired 5-ml samples of blood cultured in supplemented peptone broth (SPB) with 0.03% sodium polyanetholesulfonate (SPS) or Trypticase soy broth (TSB) with 0.5% sodium amylosulfate (SAS). The atmosphere of incubation (open venting units) and ratio of blood to broth (1:10) were the same for both samples. Only cultures with adequate blood samples (greater than or equal to 80% of stated volume) were compared statistically. Overall, SPB/SPS outperformed TSB/SAS. Bacteroidaceae and Eubacterium were found more often (P less than 0.05) and viridans streptococci were found sooner (P less than 10(-4)) in SPB/SPS than in TSB/SAS. Most importantly, staphylococci were found both more often (P less than 0.03) and sooner (P less than 10(-7)) in SPB/SPS than in TSB/SAS. In a separate experiment, SAS slowed the growth of a clinical strain of Staphylococcus aureus in TSB. Unless important advantages can be confirmed for SAS in controlled clinical trials, SAS cannot be recommended for routine use as an anticoagulant in blood culture media. PMID:6286716

  13. Stable isotope-dilution liquid chromatography/tandem mass spectrometry method for determination of thyroxine in saliva.

    PubMed

    Higashi, Tatsuya; Ichikawa, Takuya; Shimizu, Chikara; Nagai, So; Inagaki, Shinsuke; Min, Jun Zhe; Chiba, Hitoshi; Ikegawa, Shigeo; Toyo'oka, Toshimasa

    2011-04-15

    A liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) method for the determination of thyroxine (T(4)) in human saliva has been developed and validated. The saliva was deproteinized with methanol, purified using a Strata-X™ cartridge, and subjected to LC/ESI-MS/MS. Quantification was based on selected reaction monitoring, and [(13)C(6)]-T(4) was used as the internal standard. This method allowed the reproducible (intra- and inter-assay relative standard deviations, <4.8%) and accurate (analytical recovery, 96.5-99.6%) quantification of the salivary T(4) using a 400 μl sample, and the limit of quantification was 25.0 pg/ml. A preliminary study using the developed method found that there is a diagnosable difference in the salivary T(4) concentration between the euthyroid subjects and the patients with Graves disease. PMID:21435959

  14. Determination of single and repeated red cell volumes by the indicator dilution method using carbon monoxide as the indicator

    SciTech Connect

    Fukui, M.; Shigemi, K. )

    1989-11-01

    The use of radioactive isotopes limits clinical applications of blood volume measurement in the ICU. We measured red cell volumes with carbon monoxide-labeled RBC in six dogs and five human volunteers. The measured values obtained on the dogs were compared with the simultaneous measurements with the {sup 51}Cr method; the ratio of the carbon monoxide to {sup 51}Cr values ranged from 0.86 to 1.17, and the mean ratio was 1.0 +/- 0.1 (SD), r = .93. We infer from these results that the carbon monoxide method has several advantages over the {sup 51}Cr method: (a) the short labeling time (about 1 min), (b) rapidly decreasing background levels of carbon monoxide with FIO2 1.0, and (c) repeatability at intervals of several hours.

  15. Application of the Reference Method Isotope Dilution Gas Chromatography Mass Spectrometry (ID/GC/MS) to Establish Metrological Traceability for Calibration and Control of Blood Glucose Test Systems

    PubMed Central

    Andreis, Elisabeth; Küllmer, Kai

    2014-01-01

    Self-monitoring of blood glucose (BG) by means of handheld BG systems is a cornerstone in diabetes therapy. The aim of this article is to describe a procedure with proven traceability for calibration and evaluation of BG systems to guarantee reliable BG measurements. Isotope dilution gas chromatography mass spectrometry (ID/GC/MS) is a method that fulfills all requirements to be used in a higher-order reference measurement procedure. However, this method is not applicable for routine measurements because of the time-consuming sample preparation. A hexokinase method with perchloric acid (PCA) sample pretreatment is used in a measurement procedure for such purposes. This method is directly linked to the ID/GC/MS method by calibration with a glucose solution that has an ID/GC/MS-determined target value. BG systems are calibrated with whole blood samples. The glucose levels in such samples are analyzed by this ID/GC/MS-linked hexokinase method to establish traceability to higher-order reference material. For method comparison, the glucose concentrations in 577 whole blood samples were measured using the PCA-hexokinase method and the ID/GC/MS method; this resulted in a mean deviation of 0.1%. The mean deviation between BG levels measured in >500 valid whole blood samples with BG systems and the ID/GC/MS was 1.1%. BG systems allow a reliable glucose measurement if a true reference measurement procedure, with a noninterrupted traceability chain using ID/GC/MS linked hexokinase method for calibration of BG systems, is implemented. Systems should be calibrated by means of a traceable and defined measurement procedure to avoid bias. PMID:24876614

  16. QUALITY ASSURANCE PROCEDURES: METHOD 5G DETERMINATION OF PARTICULATE EMISSIONS FROM WOOD HEATERS FROM A DILUTION TUNNEL SAMPLING LOCATION

    EPA Science Inventory

    Quality assurance procedures are contained in this comprehensive document intended to be used as an aid for wood heater manufacturers and testing laboratories in performing particulate matter sampling of wood heaters according to EPA protocol, Method 5G. These procedures may be u...

  17. In Silico Calculation of Infinite Dilution Activity Coefficients of Molecular Solutes in Ionic Liquids: Critical Review of Current Methods and New Models Based on Three Machine Learning Algorithms.

    PubMed

    Paduszyński, Kamil

    2016-08-22

    The aim of the paper is to address all the disadvantages of currently available models for calculating infinite dilution activity coefficients (γ(∞)) of molecular solutes in ionic liquids (ILs)-a relevant property from the point of view of many applications of ILs, particularly in separations. Three new models are proposed, each of them based on distinct machine learning algorithm: stepwise multiple linear regression (SWMLR), feed-forward artificial neural network (FFANN), and least-squares support vector machine (LSSVM). The models were established based on the most comprehensive γ(∞) data bank reported so far (>34 000 data points for 188 ILs and 128 solutes). Following the paper published previously [J. Chem. Inf. Model 2014, 54, 1311-1324], the ILs were treated in terms of group contributions, whereas the Abraham solvation parameters were used to quantify an impact of solute structure. Temperature is also included in the input data of the models so that they can be utilized to obtain temperature-dependent data and thus related thermodynamic functions. Both internal and external validation techniques were applied to assess the statistical significance and explanatory power of the final correlations. A comparative study of the overall performance of the investigated SWMLR/FFANN/LSSVM approaches is presented in terms of root-mean-square error and average absolute relative deviation between calculated and experimental γ(∞), evaluated for different families of ILs and solutes, as well as between calculated and experimental infinite dilution selectivity for separation problems benzene from n-hexane and thiophene from n-heptane. LSSVM is shown to be a method with the lowest values of both training and generalization errors. It is finally demonstrated that the established models exhibit an improved accuracy compared to the state-of-the-art model, namely, temperature-dependent group contribution linear solvation energy relationship, published in 2011 [J. Chem

  18. Production of 1,3-propanediol by Klebsiella pneumoniae from glycerol broth.

    PubMed

    Cheng, Ke-Ke; Zhang, Jian-An; Liu, De-Hua; Sun, Yan; Yang, Ming-De; Xu, Jing-Ming

    2006-11-01

    Broth containing 152 g glycerol l(-1) from Candida krusei culture was converted to 1,3-propanediol by Klebsiella pneumoniae. Residual glucose in the broth promoted growth of K. pneumoniae while acetate was inhibitory. After desalination treatment of glycerol broth by electrodialysis, the acetate in the broth was removed. A fed-batch culture with electrodialytically pretreated broth as substrate was developed giving 53 g 1,3-propanediol l(-1) with a yield of 0.41 g g(-1) glycerol and a productivity of 0.94 g l(-1) h(-1). PMID:16912919

  19. Pre-treatment step with Leuconostoc mesenteroides or L. pseudomesenteroides strains removes furfural from Zymomonas mobilis ethanolic fermentation broth.

    PubMed

    Hunter, William J; Manter, Daniel K

    2014-10-01

    Furfural is an inhibitor of growth and ethanol production by Zymomonas mobilis. This study used a naturally occurring (not GMO) biological pre-treatment to reduce that amount of furfural in a model fermentation broth. Pre-treatment involved inoculating and incubating the fermentation broth with strains of Leuconostoc mesenteroides or Leuconostoc pseudomesenteroides. The Leuconostoc strains converted furfural to furfuryl alcohol without consuming large amounts of dextrose in the process. Coupling this pre-treatment to ethanolic fermentation reduced furfural in the broth and improved growth, dextrose uptake and ethanol formation. Pre-treatment permitted ethanol formation in the presence of 5.2 g L(-1) furfural, which was otherwise inhibitive. The pre-treatment and presence of the Leuconostoc strains in the fermentation broth did not interfere with Z. mobilis ethanolic fermentation or the amounts of ethanol produced. The method suggests a possible technique for reducing the effect that furfural has on the production of ethanol for use as a biofuel. PMID:25048957

  20. Isotope dilution mass spectrometry

    NASA Astrophysics Data System (ADS)

    Heumann, Klaus G.

    1992-09-01

    In the past isotope dilution mass spectrometry (IDMS) has usually been applied using the formation of positive thermal ions of metals. Especially in calibrating other analytical methods and for the certification of standard reference materials this type of IDMS became a routine method. Today, the progress in this field lies in the determination of ultra trace amounts of elements, e.g. of heavy metals in Antarctic ice and in aerosols in remote areas down to the sub-pg g-1 and sub-pg m-3 levels respectively, in the analysis of uranium and thorium at concentrations of a few pg g-1 in sputter targets for the production of micro- electronic devices or in the determination of sub-picogram amounts of230Th in corals for geochemical age determinations and of226Ra in rock samples. During the last few years negative thermal ionization IDMS has become a frequently used method. The determination of very small amounts of selenium and technetium as well as of other transition metals such as vanadium, chromium, molybdenum and tungsten are important examples in this field. Also the measurement of silicon in connection with a re-determination of Avogadro's number and osmium analyses for geological age determinations by the Re/Os method are of special interest. Inductively-coupled plasma mass spectrometry is increasingly being used for multi-element analyses by the isotope dilution technique. Determinations of heavy metals in samples of marine origin are representative examples for this type of multi-element analysis by IDMS. Gas chromatography-mass spectrometry systems have also been successfully applied after chelation of metals (for example Pt determination in clinical samples) or for the determination of volatile element species in the environment, e.g. dimethyl sulfide. However, IDMS--specially at low concentration levels in the environment--seems likely to be one of the most powerful analytical methods for speciation in the future. This has been shown, up to now, for species of

  1. Comparison of growth kinetics for healthy and heat-injured Listeria monocytogenes in eight enrichment broths.

    PubMed

    Silk, Todd M; Roth, Tatiana M T; Donnelly, C W

    2002-08-01

    Detection of Listeria in food products is often limited by performance of enrichment media used to support growth of Listeria to detectable levels. In this study, growth curves were generated using healthy and heat-injured Listeria monocytogenes strain F5069 in three nonselective and five selective enrichment broths. Nonselective enrichment media included the current Food and Drug Administration Bacteriological Analytical Manual Listeria enrichment broth base (BAM), Listeria repair broth (LRB), and Trypticase soy broth. Selective enrichment media included BAM with selective agents and LRB with selective agents, BCM L. monocytogenes preenrichment broth, Fraser broth, and UVM-modified Listeria enrichment broth. The Gompertz equation was used to model the growth of L. monocytogenes. Gompertz parameters were used to calculate exponential growth rate, lag-phase duration (LPD), generation time, maximum population density (MPD), and time required for repair of injured cells. Statistical differences (P < 0.05) in broth performance were noted for LPD and MPD when healthy and injured cells were inoculated into the broths. With the exception of Fraser broth, there were no significant differences in the time required for the repair of injured cells. Results indicate that the distinction between selective and nonselective broths in their ability to grow healthy Listeria and to repair sublethally injured cells is not solely an elementary issue of presence or absence of selective agents. PMID:12182490

  2. Quality-assurance procedures: Method 5G determination of particulate emissions from wood heaters from a dilution tunnel sampling location

    SciTech Connect

    Ward, T.E.; Hartman, M.W.; Olin, R.C.; Rives, G.D.

    1989-06-01

    Quality-assurance procedures are contained in this comprehensive document intended to be used as an aid for wood-heater manufacturers and testing laboratories in performing particulate matter sampling of wood heaters according to EPA protocol, Method 5G. These procedures may be used in research and development, and as an aid in auditing and certification testing. A detailed, step-by-step quality assurance guide is provided to aid in the procurement and assembly of testing apparatus, to clearly describe the procedures, and to facilitate data collection and reporting. Suggested data sheets are supplied that can be used as an aid for both recordkeeping and certification applications. Throughout the document, activity matrices are provided to serve as a summary reference. Checklists are also supplied that can be used by testing personnel. Finally, for the purposes of ensuring data quality, procedures are outlined for apparatus operation, maintenance, and traceability. These procedures combined with the detailed description of the sampling and analysis protocol will help ensure the accuracy and reliability of Method 5G emission-testing results.

  3. A Simplified Method for Quantifying Sulfur Mustard Adducts to Blood Proteins by Ultra-High Pressure Liquid Chromatography-Isotope Dilution Tandem Mass Spectrometry

    PubMed Central

    Pantazides, Brooke G.; Crow, Brian S.; Garton, Joshua W.; Quiñones-González, Jennifer A.; Blake, Thomas A.; Thomas, Jerry D.; Johnson, Rudolph C.

    2016-01-01

    Sulfur mustard binds to reactive cysteine residues, forming a stable sulfur-hydroxyethylthioethyl [S-HETE] adduct that can be used as a long-term biomarker of sulfur mustard exposure in humans. The digestion of sulfur mustard-exposed blood samples with proteinase K following total protein precipitation with acetone produces the tripeptide biomarker [S-HETE]-Cys-Pro-Phe. The adducted tripeptide is purified by solid phase extraction, separated by ultra-high pressure liquid chromatography, and detected by isotope dilution tandem mass spectrometry. This approach was thoroughly validated and characterized in our laboratory. The average interday relative standard deviation was ≤ 9.49%, and the range of accuracy was between 96.1-109% over a concentration range of 3.00 to 250. ng/mL with a calculated limit of detection of 1.74 ng/mL. A full 96-well plate can be processed and analyzed in 8 h which is five times faster than our previous 96-well plate method and only requires 50 µL of serum, plasma, or whole blood. Extensive ruggedness and stability studies and matrix comparisons were conducted to create a robust, easily transferrable method. As a result, a simple and high-throughput method has been developed and validated for the quantitation of sulfur mustard blood protein adducts in low volume blood specimens which should be readily adaptable for quantifying human exposures to other alkylating agents. PMID:25622494

  4. 'Dilute-and-shoot' RSLC-MS-MS method for fast detection of nerve and vesicant chemical warfare agent metabolites in urine.

    PubMed

    Rodin, Igor; Braun, Arcady; Stavrianidi, Andrey; Baygildiev, Timur; Shpigun, Oleg; Oreshkin, Dmitry; Rybalchenko, Igor

    2015-01-01

    A sensitive screening method based on fast liquid chromatography tandem mass-spectrometry (RSLC-MS-MS) has shown the feasibility of separation and detection of low concentration β-lyase metabolites of sulfur mustard and of nerve agent phosphonic acids in urine. The analysis of these compounds is of interest because they are specific metabolites of the chemical warfare agents (CWAs), sulfur mustard (HD), sarin (GB), soman (GD), VX and Russian VX (RVX). The 'dilute-and-shoot' RSLC-MS-MS method provides a sensitive and direct approach for determining CWA exposure in non-extracted non-derivatized samples from urine. Chromatographic separation of the metabolites was achieved using a reverse phase column with gradient mobile phases consisting of 0.5% formic acid in water and acetonitrile. Identification and quantification of species were achieved using electrospray ionization-tandem mass-spectrometry monitoring two precursor-to-product ion transitions for each compound. The method demonstrates linearity over at least two orders of magnitude and had detection limits of 0.5 ng/mL in urine. PMID:25326204

  5. Isotope dilution high-resolution gas chromatography/high-resolution mass spectrometry method for analysis of selected acidic herbicides in surface water.

    PubMed

    Woudneh, Million B; Sekela, Mark; Tuominen, Taina; Gledhill, Melissa

    2006-11-10

    In this work, an isotope dilution method for determination of selected acidic herbicides by high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS) was developed for surface water samples. Average percent recoveries of native analytes were observed to be between 70.8 and 93.5% and average recoveries of labeled quantification standards [(13)C(6)]2,4-D and [(13)C(6)]2,4,5-T were 85.5 and 101%, respectively. Using this method, detection limits of 0.05 ng/L for dicamba, MCPA, MCPP, and triclopyr, and 0.5 ng/L for 2,4-D were routinely achieved. The method was applied to measuring the concentration of these analytes in surface water samples collected from five sampling locations in the Lower Fraser Valley region of British Columbia, Canada. All of the herbicides monitored were detected at varying levels in the surface water samples collected. The highest concentrations detected for each analyte were 345 ng/L for 2,4-D, 317 ng/L for MCPA, 271 ng/L for MCPP, 15.7 ng/L for dicamba, and 2.18 ng/L for triclopyr. Average detection frequencies of the herbicides were 95% for MCPA, 80% for MCPP, 70% for dicamba, 65% for 2,4-D, and 46% for triclopyr. Seasonal variations of herbicide levels are also discussed. PMID:16956613

  6. An optimized method for the accurate determination of patulin in apple products by isotope dilution-liquid chromatography/mass spectrometry.

    PubMed

    Seo, Miyeong; Kim, Byungjoo; Baek, Song-Yee

    2015-07-01

    Patulin, a mycotoxin produced by several molds in fruits, has been frequently detected in apple products. Therefore, regulatory bodies have established recommended maximum permitted patulin concentrations for each type of apple product. Although several analytical methods have been adopted to determine patulin in food, quality control of patulin analysis is not easy, as reliable certified reference materials (CRMs) are not available. In this study, as a part of a project for developing CRMs for patulin analysis, we developed isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC/MS/MS) as a higher-order reference method for the accurate value-assignment of CRMs. (13)C7-patulin was used as internal standard. Samples were extracted with ethyl acetate to improve recovery. For further sample cleanup with solid-phase extraction (SPE), the HLB SPE cartridge was chosen after comparing with several other types of SPE cartridges. High-performance liquid chromatography was performed on a multimode column for proper retention and separation of highly polar and water-soluble patulin from sample interferences. Sample extracts were analyzed by LC/MS/MS with electrospray ionization in negative ion mode with selected reaction monitoring of patulin and (13)C7-patulin at m/z 153→m/z 109 and m/z 160→m/z 115, respectively. The validity of the method was tested by measuring gravimetrically fortified samples of various apple products. In addition, the repeatability and the reproducibility of the method were tested to evaluate the performance of the method. The method was shown to provide accurate measurements in the 3-40 μg/kg range with a relative expanded uncertainty of around 1%. PMID:25925860

  7. Comparison of digestion procedures and methods for quantification of trace lead in breast milk by isotope dilution inductively coupled plasma mass spectrometry

    PubMed Central

    Amarasiriwardena, Chitra J.; Jayawardene, Innocent; Lupoli, Nicola; Barnes, Ramon M.; Hernandez-Avila, Mauricio; Hu, Howard

    2014-01-01

    Measurement of lead in breast milk is an important public health consideration and can be technically quite challenging. The reliable and accurate determination of trace lead in human breast milk is difficult for several reasons including: potential for contamination during sample collection, storage, and analysis; complexities related to the high fat content of human milk; and poor analytic sensitivity at low concentrations. Breast milk lead levels from previous published studies should therefore be reviewed with caution. Due to the difficulty in identifying a method that would successfully digest samples with 100% efficiency, we evaluated three different digestion procedures including: (1) dry ashing in a muffle furnace, (2) microwave oven digestion, and (3) digestion in high pressure asher. High temperature, high pressure asher digestion was selected as the procedure of choice for the breast milk samples. Trace lead analysis was performed using isotope dilution (ID) inductively coupled plasma mass spectrometry (ICP-MS). Measured lead concentrations in breast milk samples (n = 200) from Mexico ranged from 0.2 to 6.7 ng ml−1. The precision for these measurements ranged from 0.27–7.8% RSD. Use of strict contamination control techniques and of a very powerful digestion procedure, along with an ID-ICP-MS method for lead determination, enables us to measure trace lead levels as low as 0.2 ng ml−1 in milk (instrument detection limit = 0.01 ng ml−1). PMID:24808927

  8. Simplified method for the determination of Ru, Pd, Re, Os, Ir and Pt in chromitites and other geological materials by isotope dilution ICP-MS and acid digestion.

    PubMed

    Meisel, T; Moser, J; Fellner, N; Wegscheider, W; Schoenberg, R

    2001-03-01

    A method for the determination of low Ru, Pd, Re, Os, Ir and Pt abundances in geological reference materials by isotope dilution inductively coupled plasma mass spectrometry (ICP-MS) after acid digestion in a high pressure asher (HPA-S) is presented. The digestion technique is similar to that using Carius tubes but easier to handle and reaches higher temperatures. Osmium can be determined as OsO4 with ICP-MS directly after digestion through a sparging technique. The remaining elements are preconcentrated by means of anion column chromatography. The resin is digested directly without elution leading to high yields but this causes problems if Zr is present at higher levels in the silicate rich materials. The analytical results for international platinum group element (PGE) reference materials, chromitite CHR-Bkg, basalt TDB-1 and gabbro WGB-1, are presented and compared with literature data, demonstrating the validity of the described method. Although higher in concentration, PGEs determined for reference material WGB-1 were worse than for TDB-1 indicating a more inhomogeneous distribution of the platinum group mineral phases. The low PGE abundance chromitite standard, CHR-Bkg, is likely to be homogeneous for Ru, Re, Os and Ir and is recommended as a reference material for the study of chromitites. Detection limits (3s x total procedure blank) range from 0.012 ng (Re and Os) to 0.77 ng (Pt), which could be further improved by applying higher quality acids. PMID:11284333

  9. Comparison of digestion procedures and methods for quantification of trace lead in breast milk by isotope dilution inductively coupled plasma mass spectrometry.

    PubMed

    Amarasiriwardena, Chitra J; Jayawardene, Innocent; Lupoli, Nicola; Barnes, Ramon M; Hernandez-Avila, Mauricio; Hu, Howard; Ettinger, Adrienne S

    2013-01-01

    Measurement of lead in breast milk is an important public health consideration and can be technically quite challenging. The reliable and accurate determination of trace lead in human breast milk is difficult for several reasons including: potential for contamination during sample collection, storage, and analysis; complexities related to the high fat content of human milk; and poor analytic sensitivity at low concentrations. Breast milk lead levels from previous published studies should therefore be reviewed with caution. Due to the difficulty in identifying a method that would successfully digest samples with 100% efficiency, we evaluated three different digestion procedures including: (1) dry ashing in a muffle furnace, (2) microwave oven digestion, and (3) digestion in high pressure asher. High temperature, high pressure asher digestion was selected as the procedure of choice for the breast milk samples. Trace lead analysis was performed using isotope dilution (ID) inductively coupled plasma mass spectrometry (ICP-MS). Measured lead concentrations in breast milk samples (n = 200) from Mexico ranged from 0.2 to 6.7 ng ml(-1). The precision for these measurements ranged from 0.27-7.8% RSD. Use of strict contamination control techniques and of a very powerful digestion procedure, along with an ID-ICP-MS method for lead determination, enables us to measure trace lead levels as low as 0.2 ng ml(-1) in milk (instrument detection limit = 0.01 ng ml(-1)). PMID:24808927

  10. Development and validation of a liquid chromatography isotope dilution mass spectrometry method for the reliable quantification of alkylphenols in environmental water samples by isotope pattern deconvolution.

    PubMed

    Fabregat-Cabello, Neus; Sancho, Juan V; Vidal, Andreu; González, Florenci V; Roig-Navarro, Antoni Francesc

    2014-02-01

    We present here a new measurement method for the rapid extraction and accurate quantification of technical nonylphenol (NP) and 4-t-octylphenol (OP) in complex matrix water samples by UHPLC-ESI-MS/MS. The extraction of both compounds is achieved in 30min by means of hollow fiber liquid phase microextraction (HF-LPME) using 1-octanol as acceptor phase, which provides an enrichment (preconcentration) factor of 800. On the other hand we have developed a quantification method based on isotope dilution mass spectrometry (IDMS) and singly (13)C1-labeled compounds. To this end the minimal labeled (13)C1-4-(3,6-dimethyl-3-heptyl)-phenol and (13)C1-t-octylphenol isomers were synthesized, which coelute with the natural compounds and allows the compensation of the matrix effect. The quantification was carried out by using isotope pattern deconvolution (IPD), which permits to obtain the concentration of both compounds without the need to build any calibration graph, reducing the total analysis time. The combination of both extraction and determination techniques have allowed to validate for the first time a HF-LPME methodology at the required levels by legislation achieving limits of quantification of 0.1ngmL(-1) and recoveries within 97-109%. Due to the low cost of HF-LPME and total time consumption, this methodology is ready for implementation in routine analytical laboratories. PMID:24423386

  11. Measurement of methyl tert-butyl ether and tert-butyl alcohol in human blood by purge-and-trap gas chromatography-mass spectrometry using an isotope-dilution method.

    PubMed

    Bonin, M A; Ashley, D L; Cardinali, F L; McCraw, J M; Wooten, J V

    1995-01-01

    We developed an isotope-dilution method for measuring methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) in whole human blood using a purge-and-trap gas chromatographic-mass spectrometric method. The labeled analogues for MTBE and TBA were [2H12]methyl tert-butyl ether and [2H9]-tert-butyl alcohol, respectively. Volatiles were removed from the blood by direct helium purging of the liquid; were trapped on a Tenax trap; and were desorbed, cryofocused, and chromatographed on a DB-624 capillary column that was connected directly to the ion source of a mass spectrometer. Detection was by mass analysis using a double-focusing magnetic-sector mass spectrometer operating in the full-scan mode at the medium mass resolution of 3000. For the isotope-dilution method, the minimum detection limits in blood (5-10 mL) are 0.01 microgram/L for MTBE and 0.06 microgram/L for TBA. The isotope-dilution method proved to be a big improvement in recovery, reproducibility, and sensitivity over our previous analytical method, which used the labeled ketone, [4-2H3]-2-butanone, as the internal standard for both MTBE and TBA. The isotope-dilution method has sufficient sensitivity for monitoring blood levels of MTBE and TBA in populations exposed to oxygenated fuels containing MTBE. PMID:7564298

  12. Rapid and sensitive method for the determination of four EU marker polycyclic aromatic hydrocarbons in cereal-based foods using isotope-dilution GC/MS.

    PubMed

    Kacmaz, Sibel; Zelinkova, Zuzana; Wenzl, Thomas

    2016-04-01

    A rapid and sensitive method has been developed for the determination of the four European Union marker polycyclic aromatic hydrocarbons (PAHs; benz[a]anthracene, chrysene, benzo[b]fluoranthene and benzo[a]pyrene) in some cereal-based foods. The method is based on pressurised liquid extraction (PLE), solid-phase extraction clean-up (SPE) and isotope-dilution gas chromatography with mass-spectrometric detection (GC/MS). The developed method was calibrated for the content range of 0.05-12.5 µg kg(-1) (expressed on a product basis). Recoveries of PAH were monitored in each sample via the recovery of (13)C-labelled PAHs. Recovery values were in the range between 86% and 91%, with relative standard deviations (RSDs) between 5% and 9%. The achieved limits of detection for all analytes were below 0.05 µg kg(-1). The applicability of the method for the analysis of routine samples was studied by the analysis of a set of commercial bread and breakfast cereal samples. In all analysed samples, benzo[a]pyrene (BAP) was the most prevalent PAH with the content between 0.09 and 0.30 µg kg(-1). On average, samples showed low levels of the sum of the four EU marker PAHs (ΣPAH4) that ranged between 0.11 and 0.22 µg kg(-1) for bread samples and between 0.23 and 0.87 µg kg(-1) for breakfast cereal samples. The developed method was found suitable for the determination of PAHs in cereal-based foods like cornflakes and breads with total relative fat contents below 3.5%. PMID:26950570

  13. Simultaneous determination of sulfur mustard and related oxidation products by isotope-dilution LC-MS/MS method coupled with a chemical conversion.

    PubMed

    Qi, Meiling; Xu, Bin; Wu, Jianfeng; Zhang, Yajiao; Zong, Cheng; Chen, Jia; Guo, Lei; Xie, Jianwei

    2016-08-15

    Sulfur mustard (SM) is a highly reactive alkylating vesicant with high toxicity and complicated metabolism, the in vivo profile of its oxidation metabolism is not still fully known and urgently needs to be clarified well. In this work, an isotope-dilution high performance liquid chromatography-tandem mass spectrometric method coupled with chemical conversion was developed for the simultaneous quantification of SM and its oxidation products, i.e., mustard sulfoxide (SMO) and mustard sulfone (SMO2). The accurate measurement of SM and its oxidation products with high reaction activity was achived via the method of chemical conversion of 2-(3,5-bis(mercaptomethyl)phenoxy) acetic acid into stable derivative products. Method validation was performed in whole blood matrix, the linear range of the method was between 0.2 and 1000μg/L with correlation coefficients (r(2))>0.99, and the lower limits of quantification for SM, SMO and SMO2 were 1, 1, 0.2μg/L, respectively. The validated method was successfully applied to a toxicokinetics research of SM and its oxidation products after SM dermal exposed rats in a single dose. All three target analytes were found in whole blood samples from poisoned rats, and significant time-dependent responses were also observed. Among them, SMO2 with relatively high toxicity was identified and quantified in vivo for the first time, while SMO was the major product in whole blood and some of them continued to be oxidized to SMO2in vivo. These results give a direct experimental evidence to support that a large amount of SM is converted into the corresponding SMO and SMO2, and these oxidation products might cause potential combined toxic effects. PMID:27322628

  14. Impact of recycling stillage on conversion of dilute sulfuric acid pretreated corn stover to ethanol.

    PubMed

    Mohagheghi, Ali; Schell, Daniel J

    2010-04-01

    Both the current corn starch to ethanol industry and the emerging lignocellulosic biofuels industry view recycling of spent fermentation broth or stillage as a method to reduce fresh water use. The objective of this study was to understand the impact of recycling stillage on conversion of corn stover to ethanol. Sugars in a dilute-acid pretreated corn stover hydrolysate were fermented to ethanol by the glucose-xylose fermenting bacteria Zymomonas mobilis 8b. Three serial fermentations were performed at two different initial sugar concentrations using either 10% or 25% of the stillage as makeup water for the next fermentation in the series. Serial fermentations were performed to achieve near steady state concentration of inhibitors and other compounds in the corn stover hydrolysate. Little impact on ethanol yields was seen at sugar concentrations equivalent to pretreated corn stover slurry at 15% (w/w) with 10% recycle of the stillage. However, ethanol yields became progressively poorer as the sugar concentration increased and fraction of the stillage recycled increased. At an equivalent corn stover slurry concentration of 20% with 25% recycled stillage the ethanol yield was only 5%. For this microorganism with dilute-acid pretreated corn stover, recycling a large fraction of the stillage had a significant negative impact on fermentation performance. Although this finding is of concern for biochemical-based lignocellulose conversion processes, other microorganism/pretreatment technology combinations will likely perform differently. PMID:19998277

  15. Development and validation of a stable-isotope dilution liquid chromatography-tandem mass spectrometry method for the determination of bisphenols in ready-made meals.

    PubMed

    Regueiro, Jorge; Wenzl, Thomas

    2015-10-01

    Due to their growing consumption, ready-made meals are a major dietary component for many people in today's society, representing an important potential route of human exposure to several food contaminants. The recent restrictions in the use of bisphenol A have led the plastic industry to look for alternative chemicals, most of them belonging to the same family of p,p'-bisphenols. The aim of the current work was to develop and validate a method based on stable-isotope dilution liquid chromatography-tandem mass spectrometry for the analysis of bisphenol A and its main analogs - bisphenol S, 4,4'-sulfonylbis(2-methylphenol), bisphenol F, bisphenol E, bisphenol B, bisphenol Z, bisphenol AF, bisphenol AP, tetrabromobisphenol A and bisphenol P - in solid foodstuffs, and particularly in ready-made meals. Extraction was carried out by ultrasound-assisted extraction after sample disruption with sand. A selective solid-phase extraction procedure was then applied to reduce potential matrix interferences. Derivatization of bisphenols with pyridine-3-sulfonyl chloride increased their ionization efficiency by electrospray ionization. Validation of the proposed method was performed in terms of selectivity, matrix effects, linearity, precision, measurement uncertainty, trueness and limits of detection. Satisfactory repeatability and intermediate precision were obtained; the related relative standard deviations were ≤7.8% and ≤10%, respectively. The relative expanded uncertainty (k=2) was below 17% for all bisphenol analogs and the trueness of the method was demonstrated by spike recovery experiments. Low limits of detection, in the range from 0.025μgkg(-1) to 0.140μgkg(-1), were obtained for all compounds. To demonstrate the applicability of the proposed method, it was eventually applied to several ready-made meals purchased from different supermarkets in Belgium. PMID:26456223

  16. Microstructural and Optical properties of transition metal (Cu) doped ZnO diluted magnetic semiconductor nano thin films fabricated by sol gel method

    NASA Astrophysics Data System (ADS)

    Ozturk, Ozgur; Asikuzun, Elif; Tasci, A. Tolga; Arda, Lutfi; Demirozu Senol, Sevim; Celik, Sukru; Terzioglu, Cabir

    Undoped and Cu (Copper) doped ZnO (Zn1-xCuxO) semiconductor thin films were produced by using sol-gel method. Cu was doped 1%, 2%, 3%, 4% and 5% ratio. Methanol and monoethanolamine (MEA) were used as solvent and stabilizer. In this study, the effect of Cu doping was investigated on microstructural and optical properties of ZnO DMS thin films. XRD, SEM, AFM and UV-VIS spectrometer measurements were performed for the microstructural and optical characterization. XRD, SEM and AFM results were showed that all of Cu doped ZnO based thin films have a hexagonal structure. The grain size of Cu doped ZnO thin films and morphology of surface were changed with increasing Cu doping. The optical transmittance of transition metal (Cu) doped ZnO thin films were decreased with doping. Keywords:Diluted Magnetic Semiconductor (DMS), Thin Film, Cu-doping, Bandgap Energy, ZnO. This research has been supported by the Kastamonu University Scientific Research Projects Coordination Department under the Grant No. KU-BAP-05/2015-12 and the Scientific and Technological Research Council of Turkey (TUBITAK) Project No. 114F259.

  17. Stable isotope dilution HILIC-MS/MS method for accurate quantification of glutamic acid, glutamine, pyroglutamic acid, GABA and theanine in mouse brain tissues.

    PubMed

    Inoue, Koichi; Miyazaki, Yasuto; Unno, Keiko; Min, Jun Zhe; Todoroki, Kenichiro; Toyo'oka, Toshimasa

    2016-01-01

    In this study, we developed the stable isotope dilution hydrophilic interaction liquid chromatography with tandem mass spectrometry (HILIC-MS/MS) technique for the accurate, reasonable and simultaneous quantification of glutamic acid (Glu), glutamine (Gln), pyroglutamic acid (pGlu), γ-aminobutyric acid (GABA) and theanine in mouse brain tissues. The quantification of these analytes was accomplished using stable isotope internal standards and the HILIC separating mode to fully correct the intramolecular cyclization during the electrospray ionization. It was shown that linear calibrations were available with high coefficients of correlation (r(2)  > 0.999, range from 10 pmol/mL to 50 mol/mL). For application of the theanine intake, the determination of Glu, Gln, pGlu, GABA and theanine in the hippocampus and central cortex tissues was performed based on our developed method. In the region of the hippocampus, the concentration levels of Glu and pGlu were significantly reduced during reality-based theanine intake. Conversely, the concentration level of GABA increased. This result showed that transited theanine has an effect on the metabolic balance of Glu analogs in the hippocampus. PMID:26033549

  18. Isolation of Shiga Toxin-Producing Escherichia coli from Ground Beef Using Multiple Combinations of Enrichment Broths and Selective Agars.

    PubMed

    Brusa, Victoria; Piñeyro, Pablo E; Galli, Lucía; Linares, Luciano H; Ortega, Emanuel E; Padola, Nora L; Leotta, Gerardo A

    2016-03-01

    Shiga toxin-producing Escherichia coli (STEC) are foodborne pathogens, and beef cattle are recognized as the principal reservoir. The aims of this study were (1) to identify the most sensitive combination of selective enrichment broths and agars for STEC isolation in artificially inoculated ground beef samples, and (2) to evaluate the most efficient combination(s) of methods for naturally contaminated ground beef samples. A total of 192 ground beef samples were artificially inoculated with STEC and non-stx bacterial strains. A combination of four enrichment broths and three agars were evaluated for sensitivity, specificity, and positive predictive value for STEC isolation from experimentally inoculated samples. Enrichments with either modified tryptic soy broth (mTSB) containing 8 mg/L novobiocin (mTSB-8) or modified Escherichia coli (mEC) broth followed by isolation in MacConkey agar were the most sensitive combinations for STEC isolation of artificially inoculated samples. Independently, both enrichments media followed by isolation in MacConkey were used to evaluate ground beef samples from 43 retail stores, yielding 65.1% and 58.1% stx-positive samples by RT-PCR, respectively. No difference was observed in the isolate proportions between these two methods (8/25 [32%] and 8/28 [28.6%]). Identical serotypes and stx genotypes were observed in STEC strains isolated from the same samples by either method. In this study, no single enrichment protocol was sufficient to detect all STEC in artificially inoculated samples and had considerable variation in detection ability with naturally contaminated samples. Moreover, none of the single or combinations of multiple isolation agars used were capable of identifying all STEC serogroups in either artificially inoculated or naturally occurring STEC-contaminated ground beef. Therefore, it may be prudent to conclude that there is no single method or combination of isolation methods capable of identifying all STEC serogroups

  19. Biodegradation of 1,2,3,4-tetrachlorodibenzo-p-dioxin in liquid broth by brown-rot fungi.

    PubMed

    Perlatti, Bruno; da Silva, Maria Fátima das Graças Fernandes; Fernandes, João Batista; Forim, Moacir Rossi

    2013-11-01

    Dioxins are a class of extremely hazardous molecules that might pose a threat to the environment. This work evaluated the microbial degradation of 1,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-TCDD), in liquid broth using three brown-rot fungi and one white-rot fungi as control. A fast and reliable extraction method with recoveries of over 98% together with a validated GC-MS method was developed, and applied to quantify 1,2,3,4-TCDD in liquid broth, mycelia and reaction flask, with detection limits of 10 ppb. Among the four strains tested, brown-rot fungus Aspergillus aculeatus showed best results, removing up to 21% of dioxin after 30-day incubation. The results open both a path for biotechnological interest in bioremediation purposes and environmental behavior studies by using brown-rot fungus. PMID:24080442

  20. Effect of fermented broth from lactic acid bacteria on pathogenic bacteria proliferation.

    PubMed

    Gutiérrez, S; Martínez-Blanco, H; Rodríguez-Aparicio, L B; Ferrero, M A

    2016-04-01

    In this study, the effect that 5 fermented broths of lactic acid bacteria (LAB) strains have on the viability or proliferation and adhesion of 7 potentially pathogenic microorganisms was tested. The fermented broth from Lactococcus lactis C660 had a growth inhibitory effect on Escherichia coli K92 that reached of 31%, 19% to Pseudomonas fluorescens, and 76% to Staphylococcus epidermidis. The growth of Staph. epidermidis was negatively affected to 90% by Lc. lactis 11454 broth, whereas the growth of P. fluorescens (25%) and both species of Staphylococcus (35% to Staphylococcus aureus and 76% to Staph. epidermidis) were inhibited when they were incubated in the presence of Lactobacillus casei 393 broth. Finally, the fermented broth of Lactobacillus rhamnosus showed an inhibitory effect on growth of E. coli K92, Listeria innocua, and Staph. epidermidis reached values of 12, 28, and 76%, respectively. Staphylococcus epidermidis was the most affected strain because the effect was detected from the early stages of growth and it was completely abolished. The results of bacterial adhesion revealed that broths from Lc. lactis strains, Lactobacillus paracasei, and Lb. rhamnosus caused a loss of E. coli K92 adhesion. Bacillus cereus showed a decreased of adhesion in the presence of the broths of Lc. lactis strains and Lb. paracasei. Listeria innocua adhesion inhibition was observed in the presence of Lb. paracasei broth, and the greatest inhibitory effect was registered when this pathogenic bacterium was incubated in presence of Lc. lactis 11454 broth. With respect to the 2 Pseudomonas, we observed a slight adhesion inhibition showed by Lactobacillus rhamnosus broth against Pseudomonas putida. These results confirm that the effect caused by the different LAB assayed is also broth- and species-specific and reveal that the broth from LAB tested can be used as functional bioactive compounds to regulate the adhesion and biofilm synthesis and ultimately lead to preventing food and

  1. A universal SI-traceable isotope dilution mass spectrometry method for protein quantitation in a matrix by tandem mass tag technology.

    PubMed

    Li, Jiale; Wu, Liqing; Jin, Youxun; Su, Ping; Yang, Bin; Yang, Yi

    2016-05-01

    Isotope dilution mass spectrometry (IDMS), an important metrological method, is widely used for absolute quantification of peptides and proteins. IDMS employs an isotope-labeled peptide or protein as an internal standard although the use of a protein provides improved accuracy. Generally, the isotope-labeled protein is obtained by stable isotope labeling by amino acids in cell culture (SILAC) technology. However, SILAC is expensive, laborious, and time-consuming. To overcome these drawbacks, a novel universal SI-traceable IDMS method for absolute quantification of proteins in a matrix is described with human transferrin (hTRF). The hTRF and a human serum sample were labeled with different tandem mass tags (TMTs). After mixing the TMT-labeled hTRF and serum sample together followed by digestion, the peptides were separated by nano-liquid chromatography and analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Using the signature peptides, we calculated the ratios of reporter ions from the TMT-labeled peptides which, in turn, allowed determination of the mass fraction of hTRF. The recovery ranged from 97% to 105% with a CV of 3.9%. The LOD and LOQ were 1.71 × 10(-5) g/g and 5.69 × 10(-5) g/g of hTRF in human serum, respectively, and the relative expanded uncertainty was 4.7% with a mass fraction of 2.08 mg/g. For comparison, an enzyme-linked immunosorbent assay (ELISA) method for hTRF yielded a mass fraction of 2.03 mg/g. This method provides a starting point for establishing IDMS technology to accurately determine the mass fractions of protein biomarkers in a matrix with traceability to SI units. This technology should support the development of a metrological method useful for quantification of a wide variety of proteins. PMID:26942737

  2. Development and Optimization of a Novel Immunomagnetic Separation- Bacteriophage Assay for Detection of Salmonella enterica Serovar Enteritidis in Broth

    PubMed Central

    Favrin, Stacy J.; Jassim, Sabah A.; Griffiths, Mansel W.

    2001-01-01

    Salmonella is the second-leading cause of food-borne illness in most developed countries, causing diarrhea, cramps, vomiting, and often fever. Many rapid methods are available for detection of Salmonella in foods, but these methods are often insensitive or expensive or require a high degree of technical ability to perform. In this paper we describe development and characterization of a novel assay that utilizes the normal infection cycle of bacteriophage SJ2 for detection of Salmonella enterica serovar Enteritidis in broth. The assay consists of four main stages: (i) capture and concentration of target cells by using immunomagnetic separation (IMS); (ii) infection of the target bacterium with phage; (iii) amplification and recovery of progeny phage; and (iv) assay of progeny phage on the basis of their effect on a healthy population of host cells (signal-amplifying cells). The end point of the assay can be determined by using either fluorescence or optical density measurements. The detection limit of the assay in broth is less than 104 CFU/ml, and the assay can be performed in 4 to 5 h. The results of this study demonstrate that the IMS-bacteriophage assay is a rapid, simple, and sensitive technique for detection of Salmonella serovar Enteritidis in broth cultures which can be applied to preenriched food samples. PMID:11133448

  3. Effects of incubation temperature, inoculum size, and medium on agreement of macro- and microdilution broth susceptibility test results for yeasts.

    PubMed Central

    Cook, R A; McIntyre, K A; Galgiani, J N

    1990-01-01

    We examined the effects of temperature and inoculum on the agreement of macro- and microdilution broth MICs of five antifungal agents against six isolates of Candida species or Torulopsis glabrata. Incubation temperature affected results with amphotericin B, flucytosine, fluconazole, and SCH 39304, producing better agreement at 35 degrees C than at 37 degrees C. Agreement between methods was better with an inoculum size of 10(2) than with one of 10(4) yeast cells per ml in testing fluconazole or SCH 39304, and the discrepancies seen with a higher incubation temperature and a larger inoculum appeared to be additive. However, inoculum size did not seem to affect agreement between methods in testing amphotericin B, flucytosine, or ketoconazole. Regardless of test conditions, macrodilution broth MICs of amphotericin B for different isolates were strikingly higher than microdilution test MICs, with mean differences being greater than ninefold under some test conditions. We conclude that for most currently available antifungal agents, an incubation temperature of 35 degrees C and a starting yeast inoculum of less than 10(4) cells per ml improve the agreement between macro- and microdilution broth tests. PMID:2221863

  4. Dilution, Concentration, and Flotation

    ERIC Educational Resources Information Center

    Liang, Ling; Schmuckler, Joseph S.

    2004-01-01

    As both classroom teaching practice and literature show, many students have difficulties learning science concepts such as density. Here are some investigations that identify the relationship between density and floating through experimenting with successive dilution of a liquid, or the systematic change of concentration of a saltwater solution.…

  5. Helium dilution refrigeration system

    DOEpatents

    Roach, P.R.; Gray, K.E.

    1988-09-13

    A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation is disclosed. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains [sup 3]He and [sup 4]He liquids which are precooled by a coupled container containing [sup 3]He liquid, enabling the phase separation of a [sup 3]He rich liquid phase from a dilute [sup 3]He-[sup 4]He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the [sup 3]He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute [sup 3]He-[sup 4]He liquid phase. 2 figs.

  6. Helium dilution refrigeration system

    DOEpatents

    Roach, Patrick R.; Gray, Kenneth E.

    1988-01-01

    A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains .sup.3 He and .sup.4 He liquids which are precooled by a coupled container containing .sup.3 He liquid, enabling the phase separation of a .sup.3 He rich liquid phase from a dilute .sup.3 He-.sup.4 He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the .sup.3 He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute .sup.3 He-.sup.4 He liquid phase.

  7. A candidate reference method for the determination of uric acid in serum based on high performance liquid chromatography, compared with an isotope dilution-gas chromatography-mass spectrometer method.

    PubMed

    Kock, R; Delvoux, B; Tillmanns, U; Greiling, H

    1989-03-01

    A method based on isocratic high performance liquid chromatography (HPLC) with UV detection at 292 nm is proposed as a candidate reference method for the determination of uric acid. Data obtained by this method are compared with those from an isotope dilution-gas chromatography-mass spectrometric method (ID-GC-MS), using [1,3-15N2]uric acid as internal standard and selected mass detection at m/z = 456 and m/z = 458. The inaccuracy of the ID-GC-MS method is maximally 0.4% for NBS-SRM-909 control sera with a concentration of 483 mumol/l. The coefficient of variation between days is 0.26%-0.80% and 0.37-0.90% for 14 control sera from other suppliers. The maximum bias of the HPLC method is 0.6%, and the coefficient of variation between days is 0.31%-0.65% for NBS-SRM-909 control sera. The coefficient of variation between days for the other 14 control sera tested is 0.35%-0.66%. Comparison of the HPLC method with the reference ID-GC-MS method resulted in a coefficient of correlation of r = 0.9998 (n = 14). The concentration of uric acid in the tested control sera ranged from 160 to 624 mumol/l. PMID:2651552

  8. Rheology and hydrodynamic properties of Tolypocladium inflatum fermentation broth and its simulation.

    PubMed

    Benchapattarapong, N; Anderson, W A; Bai, F; Moo-Young, M

    2005-07-01

    A physico-chemical, two phase simulated pseudoplastic fermentation (SPF) broth was investigated in which Solka Floc cellulose fibre was used to simulate the filamentous biomass, and a mixture of 0.1% (w/v) carboxymethyl cellulose (CMC) and 0.15 M aqueous sodium chloride was used to simulate the liquid fraction of the fermentation broth. An investigation of the rheological behaviour and hydrodynamic properties of the SPF broth was carried out, and compared to both a fungal Tolypocladium inflatum fermentation broth and a CMC solution in a 50 L stirred tank bioreactor equipped with conventional Rushton turbines. The experimental data confirmed the ability of the two phase SPF broth to mimic both the T. inflatum broth bulk rheology as well as the mixing and mass transfer behaviour. In contrast, using a homogeneous CMC solution with a similar bulk rheology to simulate the fermentation resulted in a significant underestimation of the mass transfer and mixing times. The presence of the solid phase and its microstructure in the SPF broth appear to play a significant role in gas holdup and bubble size, thus leading to the different behaviours. The SPF broth seems to be a more accurate simulation fluid that can be used to predict the bioreactor mixing and mass transfer performance in filamentous fermentations, in comparison with CMC solutions used in some previous studies. PMID:15744504

  9. Some macronutrient content in mycelia and culture broth of medicinal mushrooms cultivated on amaranth flour.

    PubMed

    Krupodorova, Tetiana A; Barshteyn, Viktor Yu; Bisko, Nina A; Ivanova, Tetiana S

    2012-01-01

    The content of proteins, lipids, and amino and fatty acids was investigated in mycelium and culture broth of medicinal mushrooms Cordyceps sinensis, Pleurotus ostreatus, and Schizophyllum commune. Seven essential amino acids were present in the proteins of all mushroom samples, with aspartic (6.34%-14.29%) and glutamic (15.12%-17.51%) acids predominating in culture mycelium and glutamic acid (16.3%-19.1%) in culture broth. Lipids in the mycelium of species C. sinensis, P. ostreatus, and Sch. Commune consisted of 10 fatty acids and 12 fatty acids in culture broth in our experiments. Major acids in culture mycelium and culture broth of fungi were linoleic (42.43%-67.41%), oleic (10.47%-32.54%), and palmitic (16.43%-20.33%). The proteins and lipids in culture broth of studied species contained a higher level of total non-essential amino acids and unsaturated fatty acids as compared to those in culture mycelium. PMID:22577978

  10. An integrated platform for gas-diffusion separation and electrochemical determination of ethanol on fermentation broths.

    PubMed

    Giordano, Gabriela Furlan; Vieira, Luis Carlos Silveira; Gobbi, Angelo Luiz; Lima, Renato Sousa; Kubota, Lauro Tatsuo

    2015-05-22

    An integrated platform was developed for point-of-use determination of ethanol in sugar cane fermentation broths. Such analysis is important because ethanol reduces its fuel production efficiency by altering the alcoholic fermentation step when in excess. The custom-designed platform integrates gas diffusion separation with voltammetric detection in a single analysis module. The detector relied on a Ni(OH)2-modified electrode. It was stabilized by uniformly depositing cobalt and cadmium hydroxides as shown by XPS measurements. Such tests were in accordance with the hypothesis related to stabilization of the Ni(OH)2 structure by insertion of Co(2+) and Cd(2+) ions in this structure. The separation step, in turn, was based on a hydrophobic PTFE membrane, which separates the sample from receptor solution (electrolyte) where the electrodes were placed. Parameters of limit of detection and analytical sensitivity were estimated to be 0.2% v/v and 2.90 μA % (v/v)(-1), respectively. Samples of fermentation broth were analyzed by both standard addition method and direct interpolation in saline medium based-analytical curve. In this case, the saline solution exhibited ionic strength similar to those of the samples intended to surpass the tonometry colligative effect of the samples over analyte concentration data by attributing the reduction in quantity of diffused ethanol vapor majorly to the electrolyte. The approach of analytical curve provided rapid, simple and accurate analysis, thus contributing for deployment of point-of-use technologies. All of the results were accurate with respect to those obtained by FTIR method at 95% confidence level. PMID:25937104

  11. Comparison of the serum-supplemented Todd-Hewitt and the new Haemophilus test media for broth microdilution susceptibility testing of Streptococcus pneumoniae.

    PubMed

    Roger, M; Lapointe, J R

    1996-06-01

    Horse serum-supplemented Todd-Hewitt broth (STH) in use at Hôpital Ste-Justine for the last 12 years was compared to the recently proposed Haemophilus test medium (HTM), for broth microdilution susceptibility testing of Streptococcus pneumoniae. One hundred and twenty S. pneumoniae isolates from pediatric clinical specimens were used in this study. In general, the minimum inhibitory concentrations (MICs) in STH for 15 antimicrobial agents were quite comparable to those determined in HTM but tended to be higher. Drugs which generated MICs within +/- 1 log2 concentration differences in both media included penicillin, ampicillin, oxacillin, cefuroxime, cefotaxime, cefixime, clindamycin, chloramphenicol, trimethoprim-sulfamethoxazole, rifampin, ciprofloxacin and vancomycin. Cefaclor and tetracycline MICs tended to be > or = 2 log2 dilutions higher with STH for most of the isolates tested, while erythromycin MICs were often 2 log2 dilutions lower with STH than with HTM. Despite some differences in MICs noted above, few very major (0.4%), major (0.2%) and minor interpretive category errors (4.4%) were observed. The visual reading of the MICs for most of the 120 clinical isolates tested was generally easier in STH which was superior in supporting best the bacterial growth as detected by spectrophotometry. The risk of false susceptibility is thus decreased by using STH rather than HTM; furthermore, STH is free of the technical problems of the lysed horse blood Mueller-Hinton (LHB-MH) recommended by the NCCLS. PMID:8808713

  12. Efficacy of Several Enrichment Procedures Utilizing TECRA and Bolton’s Broth for Recovery of Campylobacter from Commercial Poultry Carcass Rinse Samples

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: Improvements in the cultural recovery methods for Campylobacter are essential to accurately assess the epidemiology and ecology of this organism in poultry. In a preliminary study, significantly more Campylobacter were recovered from poultry carcasses with TECRA broth than with Bolto...

  13. Lethal paralytic shellfish poisoning from consumption of green mussel broth, Western Samar, Philippines, August 2013

    PubMed Central

    Ramos, Ruth Alma; de los Reyes, Vikki Carr; Sucaldito, Ma Nemia; Tayag, Enrique

    2015-01-01

    Background In July 2013, the Philippines’ Event-Based Surveillance & Response Unit received a paralytic shellfish poisoning (PSP) report from Tarangnan, Western Samar. A team from the Department of Health conducted an outbreak investigation to identify the implicated source and risk factors in coastal villages known for green mussel production and exportation. Methods A case was defined as a previously well individual from Tarangan, Western Samar who developed gastrointestinal symptoms and any motor and/or sensory symptoms after consumption of shellfish from 29 June to 4 July 2013 in the absence of any known cause. The team reviewed medical records, conducted active case finding and a case-control study. Relatives of cases who died were interviewed. Sera and urine specimens, green mussel and seawater samples were tested for saxitoxin levels using high performance liquid chromatography. Results Thirty-one cases and two deaths were identified. Consumption of > 1 cup of green mussel broth was associated with being a case. Seawater sample was positive for Pyrodinium bahamense var. compressum and green mussel samples were positive for saxitoxin. Inspection revealed villagers practice open defecation and improper garbage disposal. Conclusion This PSP outbreak was caused by the consumption of the green mussel broth contaminated by saxitoxin. As a result of this outbreak, dinoflagellate and saxitoxin surveillance was established, and since the outbreak, there have been no harmful algal blooms event or PSP case reported since. A “Save Cambatutay Bay” movement, focusing on proper waste disposal practice and clean-up drives has been mobilized. PMID:26306212

  14. Gluconeogenesis from labeled carbon: estimating isotope dilution

    SciTech Connect

    Kelleher, J.K.

    1986-03-01

    To estimate the rate of gluconeogenesis from steady-state incorporation of labeled 3-carbon precursors into glucose, isotope dilution must be considered so that the rate of labeling of glucose can be quantitatively converted to the rate of gluconeogenesis. An expression for the value of this isotope dilution can be derived using mathematical techniques and a model of the tricarboxylic acid (TCA) cycle. The present investigation employs a more complex model than that used in previous studies. This model includes the following pathways that may affect the correction for isotope dilution: 1) flux of 3-carbon precursor to the oxaloacetate pool via acetyl-CoA and the TCA cycle; 2) flux of 4- or 5-carbon compounds into the TCA cycle; 3) reversible flux between oxaloacetate (OAA) and pyruvate and between OAA and fumarate; 4) incomplete equilibrium between OAA pools; and 5) isotope dilution of 3-carbon tracers between the experimentally measured pool and the precursor for the TCA-cycle OAA pool. Experimental tests are outlined which investigators can use to determine whether these pathways are significant in a specific steady-state system. The study indicated that flux through these five pathways can significantly affect the correction for isotope dilution. To correct for the effects of these pathways an alternative method for calculating isotope dilution is proposed using citrate to relate the specific activities of acetyl-CoA and OAA.

  15. Minimal Coital Dilution in Accra, Ghana

    PubMed Central

    Jenness, Samuel M.; Biney, Adriana A. E.; Ampofo, William Kwabena; Dodoo, F. Nii-Amoo; Cassels, Susan

    2015-01-01

    Background Coital dilution, the reduction in the coital frequency per partner when an additional ongoing partner is added, may reduce the transmission potential of partnership concurrency for HIV and other sexually transmitted infections. Empirical estimates of dilution, especially dilution of sexual acts unprotected by condoms, are needed to inform prevention research. Methods Sexually active adults in Accra, Ghana were recruited in a multi-stage household probability sample. Degree (number of ongoing partners), total acts, and unprotected acts were measured retrospectively for each month in the past year through an event-history calendar. Random effects negative binomial models estimated the association between degree and coital frequency. Results Compared to person-months with a single partner (monogamy), 2.06 times as many total acts and 1.94 times as many unprotected acts occurred in months with 2 partners. In months with 3 partners, 2.90 times as many total acts and 2.39 times as many unprotected acts occurred compared to monogamous months. Total acts but not unprotected acts also declined with partnership duration. Conclusions No dilution was observed for total acts with up to three concurrent partners, but a small amount of dilution was observed for unprotected acts for months with multiple concurrencies. This suggests moderate selective condom use in months with multiple concurrencies. The implications of the observed dilution for future HIV transmission must be investigated with mathematical models. PMID:25622062

  16. Correlation of growth of aerobic blood cultures in hypertonic broth with antibiotic therapy.

    PubMed Central

    Eng, J; Maeland, A

    1982-01-01

    The aim of this study was to elucidate the mechanisms by which sucrose improves growth in a hypertonic medium for isolating aerobes from blood. Clinical blood cultures were made routinely in duplicate in plain broth consisting of brain heart infusion broth with sodium polyanetholesulfonate, gelatin, and penicillinase and the same broth with 20% sucrose added. The growth patterns of Staphylococcus aureus and Enterobacteriaceae from plain and from hypertonic broth were correlated with the presence or absence of antimicrobial therapy in patients when the blood cultures were collected. In S. aureus bacteremias, 58.7% of the positive cultures collected during treatment of patients with beta-lactam antibiotics showed earlier growth or growth only in hypertonic broth, compared with 16.7% of the cultures taken during treatment with other antimicrobial agents (P less than 0.05) and 17.6% of the cultures made in antibiotic-free intervals (P less than 0.01). In the group of cultures yielding growth of Enterobacteriaceae, growth occurred earlier or solely in hypertonic broth in 28.9% of the cultures taken during treatment with beta-lactam antibiotics, compared with 15.7% of the cultures taken during treatment with other antimicrobial agents and 21.6% of the cultures collected in antibiotic-free intervals (differences not statistically significant). It is concluded that treatment with beta-lactam antibiotics is an important reason for the improved growth of S. aureus from hypertonic broth, but other factors are also involved. PMID:7153339

  17. Activities of clarithromycin against eight slowly growing species of nontuberculous mycobacteria, determined by using a broth microdilution MIC system.

    PubMed Central

    Brown, B A; Wallace, R J; Onyi, G O

    1992-01-01

    MICs of clarithromycin against 324 clinical isolates belonging to eight species of slowly growing nontuberculous mycobacteria were determined by using a broth microdilution system. Isolates were inoculated into twofold drug dilutions in Middlebrook 7H9 broth (pH corrected to 7.4) and then incubated at 30 degrees C for 7 days for Mycobacterium marinum and for 14 days for all other species. The MIC for 90% of the strains (MIC90) was less than or equal to 0.5 micrograms/ml for isolates of Mycobacterium gordonae (6 strains), Mycobacterium scrofulaceum (5 strains), Mycobacterium szulgai (6 strains), and Mycobacterium kansasii (35 strains). MICs for M. marinum (25 strains) and Mycobacterium avium complex (237 strains) were higher, but 100% and 89% of the strains, respectively, were susceptible to less than or equal to 4 micrograms/ml. In contrast, MICs for five of six M. simiae strains were greater than 8 micrograms/ml, and the range of MICs for Mycobacterium nonchromogenicum varied from less than or equal to 0.125 to 8 micrograms/ml. For the 237 isolates of M. avium complex, the MIC50 was 2 micrograms/ml and the MIC90 was 8 micrograms/ml. MICs for most isolates (77%) were in the 1- to 4-micrograms/ml range. For the 80 isolates in this group known to be from AIDS patients, the MIC50 was 4 micrograms/ml and the MIC90 was 8 micrograms/ml. These MIC studies combined with preliminary clinical trials suggest that clarithromycin may be useful for drug therapy of most species of the slowly growing nontuberculous mycobacteria except M. simiae. PMID:1416891

  18. Determination of 5alpha-androst-16-en-3alpha-ol in truffle fermentation broth by solid-phase extraction coupled with gas chromatography-flame ionization detector/electron impact mass spectrometry.

    PubMed

    Wang, Guan; Li, Yuan-Yuan; Li, Dong-Sheng; Tang, Ya-Jie

    2008-07-15

    A novel method using solid-phase extraction coupled with gas chromatography and flame ionization detector (FID)/electron impact mass spectrometry (EIMS) was developed for the determination of 5alpha-androst-16-en-3alpha-ol (androstenol), a steroidal compound belonging to the group of musk odorous 16-androstenes, in truffle fermentation broth. Comparison studies between FID and EIMS indicated two detectors gave similar quantitative results. The highest androstenol concentration of 123.5 ng/mL was detected in Tuber indicum fermentation broth, while no androstenol was found in Tuber aestivum fermentation broth. For the first time, this work confirmed the existence of androstenol in the truffle fermentation broth, which suggested truffle fermentation is a promising alternative for androstenol production on a large scale. PMID:18585987

  19. Automatic diluter for bacteriological samples.

    PubMed

    Trinel, P A; Bleuze, P; Leroy, G; Moschetto, Y; Leclerc, H

    1983-02-01

    The described apparatus, carrying 190 tubes, allows automatic and aseptic dilution of liquid or suspended-solid samples. Serial 10-fold dilutions are programmable from 10(-1) to 10(-9) and are carried out in glass tubes with screw caps and split silicone septa. Dilution assays performed with strains of Escherichia coli and Bacillus stearothermophilus permitted efficient conditions for sterilization of the needle to be defined and showed that the automatic dilutions were as accurate and as reproducible as the most rigorous conventional dilutions. PMID:6338826

  20. Automatic diluter for bacteriological samples.

    PubMed Central

    Trinel, P A; Bleuze, P; Leroy, G; Moschetto, Y; Leclerc, H

    1983-01-01

    The described apparatus, carrying 190 tubes, allows automatic and aseptic dilution of liquid or suspended-solid samples. Serial 10-fold dilutions are programmable from 10(-1) to 10(-9) and are carried out in glass tubes with screw caps and split silicone septa. Dilution assays performed with strains of Escherichia coli and Bacillus stearothermophilus permitted efficient conditions for sterilization of the needle to be defined and showed that the automatic dilutions were as accurate and as reproducible as the most rigorous conventional dilutions. Images PMID:6338826

  1. Self-assembling systems based on quaternized derivatives of 1,4-diazabicyclo[2.2.2]octane in nutrient broth as antimicrobial agents and carriers for hydrophobic drugs.

    PubMed

    Pashirova, Tatiana N; Lukashenko, Svetlana S; Zakharov, Sergey V; Voloshina, Alexandra D; Zhiltsova, Elena P; Zobov, Vladimir V; Souto, Eliana B; Zakharova, Lucia Ya

    2015-03-01

    Aggregation properties of mono (mono-CS) and dicationic (di-CS) surfactants, namely quaternised derivatives of 1,4-diazabicyclo[2.2.2]octane (DABCO), have been evaluated in water and in nutrient broths of different pH, i.e. in Hottinger broth (рН=7.2) and Sabouraud dextrose broth (рН=5.6). Aggregation capacity of surfactants was shown to be responsible for the solubilization properties of a complex composed of a hydrophobic probe (Sudan I) and a selected drug (quercetin), contributing to the antimicrobial activity of this surfactant system. The effect of N-methyl-d-glucamine (NmDg) additive on the antimicrobial activity of mono-CS, and its aggregation and solubilization parameters, has also been evaluated. A substantial decrease in critical micelle concentration (CMC) of cationic surfactants in nutrient broths (up to 60 times) has been reported. Twofold dilution of monocationic surfactant by NmDg slightly changed the CMC of surfactant; however, it provided a remarkable increase in solubilization capacity (∼by 4 times) and decrease in its toxicity. The data anticipate the potential use of DABCO quaternized derivatives as innovative non-toxic delivery systems for hydrophobic drugs. PMID:25687097

  2. Analysis of mixtures of fatty acids and fatty alcohols in fermentation broth.

    PubMed

    Liu, Yilan; Chen, Ting; Yang, Maohua; Wang, Caixia; Huo, Weiyan; Yan, Daojiang; Chen, Jinjin; Zhou, Jiemin; Xing, Jianmin

    2014-01-01

    Microbial production of fatty acids and fatty alcohols has attracted increasing concerns because of energy crisis and environmental impact of fossil fuels. Therefore, simple and efficient methods for the extraction and quantification of these compounds become necessary. In this study, a high-performance liquid chromatography-refractive index detection (HPLC-RID) method was developed for the simultaneous quantification of fatty acids and fatty alcohols in these samples. The optimum chromatographic conditions are C18 column eluted with methanol:water:acetic acid (90:9.9:0.1, v/v/v); column temperature, 26°C; flow rate, 1.0mL/min. Calibration curves of all selected analytes showed good linearity (r(2)≥0.9989). The intra-day and inter-day relative standard deviations (RSDs) of the 10 compounds were less than 4.46% and 5.38%, respectively, which indicated that the method had good repeatability and precision. Besides, a method for simultaneous extraction of fatty acids and fatty alcohols from fermentation broth was optimized by orthogonal design. The optimal extraction conditions were as follows: solvent, ethyl acetate; solvent to sample ratio, 0.5:1; rotation speed, 2min at 260rpm; extraction temperature, 10°C. This study provides simple and fast methods to simultaneously extract and quantify fatty acids and fatty alcohols for the first time. It will be useful for the study of microbial production of these products. PMID:24290170

  3. Energy efficient recovery and dehydration of ethanol from fermentation broths by Membrane Assisted Vapor Stripping technology

    EPA Science Inventory

    Distillation combined with molecular sieve dehydration is the current state of the art for fuel grade ethanol production from fermentation broths. To improve the sustainability of bioethanol production, energy efficient separation alternatives are needed, particularly for lower ...

  4. Fructo-oligosaccharides purification from a fermentative broth using an activated charcoal column.

    PubMed

    Nobre, C; Teixeira, J A; Rodrigues, L R

    2012-02-15

    In this study, a simple and efficient process to purify fructo-oligosaccharides (FOS) from a fermentative broth was proposed using a single activated charcoal column. The FOS adsorption onto the activated charcoal was modeled by a pseudo-second order model. Several volumes and concentrations of water/ethanol were studied to optimize the selective desorption of sugars from the broth mixture at 25°C. Mixtures containing 50.6% (w/w) of FOS (FOS content in the fermentative broth) were purified to 92.9% (w/w) with a FOS recovery of 74.5% (w/w). Moreover, with the proposed process, fractions with purity up to 97% (w/w) of FOS were obtained. This purification process was also found to be efficient in the desalting of the fermentative broth. PMID:22100432

  5. Membrane-based recovery and dehydration of alcohols from fermentation broths - of materials and modules

    EPA Science Inventory

    Distillation combined with molecular sieve dehydration is the current state of the art for fuel grade ethanol production from fermentation broths. As the liquid biofuels industry transitions to lignocellulosic feedstocks, expands the end product portfolio to include other alcoho...

  6. A new cyclopeptide with antifungal activity from the co-culture broth of two marine mangrove fungi.

    PubMed

    Li, Chunyuan; Wang, Jinhua; Luo, Cuiping; Ding, Weijia; Cox, Daniel G

    2014-01-01

    A new cyclic tetrapeptide, cyclo-(L-leucyl-trans-4-hydroxy-L-prolyl-D-leucyl-trans-4-hydroxy-L-proline) (1), was isolated from the co-culture broth of two mangrove fungi Phomopsis sp. K38 and Alternaria sp. E33. The structure of 1 was determined by analysis of spectroscopic data and Marfey's analytic method. Primary bioassay demonstrated that compound 1 exhibited moderate to high inhibitory activity against four crop-threatening fungi including Gaeumannomyces graminis, Rhizoctonia cerealis, Helminthosporium sativum and Fusarium graminearum as compared with triadimefon. PMID:24571709

  7. Molecular speciated isotope dilution mass spectrometric methods for accurate, reproducible and direct quantification of reduced, oxidized and total glutathione in biological samples.

    PubMed

    Fahrenholz, Timothy; Wolle, Mesay Mulugeta; Kingston, H M Skip; Faber, Scott; Kern, John C; Pamuku, Matt; Miller, Logan; Chatragadda, Hemasudha; Kogelnik, Andreas

    2015-01-20

    Novel protocols were developed to accurately quantify reduced (GSH), oxidized (GSSG) and total (tGSH) glutathione in biological samples using molecular speciated isotope dilution mass spectrometry (SIDMS). For GSH and GSSG measurement, the sample was spiked with isotopically enriched analogues of the analytes ((310)GSH and (616)GSSG), along with N-ethylmaleimide (NEM), and treated with acetonitrile to solubilize the endogenous analytes via protein precipitation and equilibrate them with the spikes. The supernatant was analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the analytes were quantified with simultaneous tracking and correction for auto-oxidation of GSH to GSSG. For tGSH assay, a (310)GSH-spiked sample was treated with dithiothreitol (DTT) to convert disulfide-bonded glutathione to GSH. After removing the protein, the supernatant was analyzed by LC-MS/MS and the analyte was quantified by single-spiking isotope dilution mass spectrometry (IDMS). The mathematical relationships in IDMS and SIDMS quantifications are based on isotopic ratios and do not involve calibration curves. The protocols were validated using spike recovery tests and by analyzing synthetic standard solutions. Red blood cell (RBC) and saliva samples obtained from healthy subjects, and whole blood samples collected and shipped from a remote location were analyzed. The concentrations of tGSH in the RBC and whole blood samples were 2 orders of magnitude higher than those found in saliva. The fractions of GSSG were 0.2-2.2% (RBC and blood) and 15-47% (saliva) of the free glutathione (GSH + 2xGSSG) in the corresponding samples. Up to 3% GSH was auto-oxidized to GSSG during sample workup; the highest oxidations (>1%) were in the saliva samples. PMID:25519489

  8. Dilution jet mixing program

    NASA Technical Reports Server (NTRS)

    Srinivasan, R.; Coleman, E.; Johnson, K.

    1984-01-01

    Parametric tests were conducted to quantify the mixing of opposed rows of jets (two-sided injection) in a confined cross flow. Results show that jet penetrations for two sided injections are less than that for single-sided injections, but the jet spreading rates are faster for a given momentum ratio and orifice plate. Flow area convergence generally enhances mixing. Mixing characteristics with asymmetric and symmetric convergence are similar. For constant momentum ratio, the optimum S/H(0) with in-line injections is one half the optimum value for single sided injections. For staggered injections, the optimum S/H(0) is twice the optimum value for single-sided injection. The correlations developed predicted the temperature distributions within first order accuracy and provide a useful tool for predicting jet trajectory and temperature profiles in the dilution zone with two-sided injections.

  9. Diluted magnetic semiconductor nanowires exhibiting magnetoresistance

    DOEpatents

    Yang, Peidong; Choi, Heonjin; Lee, Sangkwon; He, Rongrui; Zhang, Yanfeng; Kuykendal, Tevye; Pauzauskie, Peter

    2011-08-23

    A method for is disclosed for fabricating diluted magnetic semiconductor (DMS) nanowires by providing a catalyst-coated substrate and subjecting at least a portion of the substrate to a semiconductor, and dopant via chloride-based vapor transport to synthesize the nanowires. Using this novel chloride-based chemical vapor transport process, single crystalline diluted magnetic semiconductor nanowires Ga.sub.1-xMn.sub.xN (x=0.07) were synthesized. The nanowires, which have diameters of .about.10 nm to 100 nm and lengths of up to tens of micrometers, show ferromagnetism with Curie temperature above room temperature, and magnetoresistance up to 250 Kelvin.

  10. Dilute acid/metal salt hydrolysis of lignocellulosics

    DOEpatents

    Nguyen, Quang A.; Tucker, Melvin P.

    2002-01-01

    A modified dilute acid method of hydrolyzing the cellulose and hemicellulose in lignocellulosic material under conditions to obtain higher overall fermentable sugar yields than is obtainable using dilute acid alone, comprising: impregnating a lignocellulosic feedstock with a mixture of an amount of aqueous solution of a dilute acid catalyst and a metal salt catalyst sufficient to provide higher overall fermentable sugar yields than is obtainable when hydrolyzing with dilute acid alone; loading the impregnated lignocellulosic feedstock into a reactor and heating for a sufficient period of time to hydrolyze substantially all of the hemicellulose and greater than 45% of the cellulose to water soluble sugars; and recovering the water soluble sugars.

  11. Development of a selective broth medium for the detection of injured Campylobacter jejuni by capacitance monitoring.

    PubMed

    Line, J Eric; Pearson, Kirsten G

    2003-10-01

    The purpose of these studies was to develop a conductimetric method for the rapid detection of Campylobacter jejuni. Numerous basal medium components were analyzed to develop a growth-enhancing broth medium for detection of freeze-injured Campylobacter cells using a conductimetric system. The final medium was composed of a modified Campy-Line agar from which the agar and triphenyltetrazolium chloride were removed and the amino acid, L-arginine was added. Pure isolates of C. jejuni. (frozen and thawed to produce stressed cells) were utilized to test the detection methodology. Monitoring of significant changes in the capacitance signal was found suitable for detection of Campylobacter proliferation. Using stressed pure cultures, Campylobacter growth was repeatedly detected at very low inoculum levels (about one cell per well). There was a direct linear relationship between detection times (DTs) and the initial inoculum level. For example, using a single strain, the mean DT (n = 20) at the 10 CFU/ml inoculum level was 28.6 h, with 100% of the inoculated wells detecting. The mean DTs at the 100, 1,000, and 10,000 CFU/ml inoculum levels were 24.9, 21.4, and 17.0 h, respectively. This study demonstrates that conductimetric methods can be utilized for the rapid detection of C. jejuni. PMID:14572208

  12. The antimicrobial effects of selenium nanoparticle-enriched probiotics and their fermented broth against Candida albicans

    PubMed Central

    2014-01-01

    Background Lactic acid bacteria are considered important probiotics for prevention of some infections. The aim of this work was to investigate the effect of selenium dioxide on the antifungal activity of Lactobacillus plantarum and L. johnsonii against Candida albicans. Methods Lactobacillus plantarum and L. johnsonii cells, grown in the presence and absence of selenium dioxide, and their cell-free spent culture media were tested for antifungal activity against C. albicans ATCC 14053 by a hole-plate diffusion method and a time-kill assay. Results Both L. plantarum and L. johnsonii reduced selenium dioxide to cell-associated elemental selenium nanoparticles. The cell-free spent culture media, from both Lactobacillus species that had been grown with selenium dioxide for 48 h, showed enhanced antifungal activity against C. albicans. Enhanced antifungal activity of cell biomass against C. albicans was also observed in cultures grown with selenium dioxide. Conclusions Selenium dioxide-treated Lactobacillus spp. or their cell-free spent broth inhibited the growth of C. albicans and should be investigated for possible use in anti-Candida probiotic formulations in future. PMID:24906455

  13. [Determination of sugars, organic acids and alcohols in microbial consortium fermentation broth from cellulose using high performance liquid chromatography].

    PubMed

    Jiang, Yan; Fan, Guifang; Du, Ran; Li, Peipei; Jiang, Li

    2015-08-01

    A high performance liquid chromatographic method was established for the determination of metabolites (sugars, organic acids and alcohols) in microbial consortium fermentation broth from cellulose. Sulfate was first added in the samples to precipitate calcium ions in microbial consortium culture medium and lower the pH of the solution to avoid the dissociation of organic acids, then the filtrates were effectively separated using high performance liquid chromatography. Cellobiose, glucose, ethanol, butanol, glycerol, acetic acid and butyric acid were quantitatively analyzed. The detection limits were in the range of 0.10-2.00 mg/L. The linear correlation coefficients were greater than 0.999 6 in the range of 0.020 to 1.000 g/L. The recoveries were in the range of 85.41%-115.60% with the relative standard deviations of 0.22% -4.62% (n = 6). This method is accurate for the quantitative analysis of the alcohols, organic acids and saccharides in microbial consortium fermentation broth from cellulose. PMID:26749855

  14. Preservation of anthocyanins in solid lipid nanoparticles: Optimization of a microemulsion dilution method using the Placket-Burman and Box-Behnken designs.

    PubMed

    Ravanfar, Raheleh; Tamaddon, Ali Mohammad; Niakousari, Mehrdad; Moein, Mahmoud Reza

    2016-05-15

    Anthocyanins are the main polyphenol components from red cabbage (Brassica oleracea L. Var. Capitata f. Rubra) extracts that have inherent antioxidant activities. Anthocyanins are effectively stable in acidic gastric digestion conditions, with nearly 100% phenol content recovery. However, the total phenol content recovery after simulated pancreatic digestion was approximately 25%. To protect anthocyanins against harsh environmental conditions (e.g., pH and temperature), solid lipid nanoparticles were prepared by the dilution of water in oil (w/o) microemulsions containing anthocyanins in aqueous media. The formulations were characterized for particle size and encapsulation efficiency. The formulation parameters (e.g., volume of the internal aqueous phase, homogenization time and the percentages of total lipid, total surfactant or stabilizer) were optimized using the Placket-Burman and Box-Behnken experimental designs. Entrapment efficiency (89.2 ± 0.3%) was calculated when the mean particle size was 455 ± 2 nm. A scanning electron microscopy study revealed the spherical morphology of the particles. PMID:26776010

  15. Detonation nanodiamonds for rapid detection of clinical isolates of Mycobacterium tuberculosis complex in broth culture media.

    PubMed

    Soo, Po-Chi; Kung, Ching-Jen; Horng, Yu-Tze; Chang, Kai-Chih; Lee, Jen-Jyh; Peng, Wen-Ping

    2012-09-18

    Routinely used molecular diagnostic methods for mycobacterium identification are expensive and time-consuming. To tackle this problem, we develop a method to streamline identification of Mycobacterium tuberculosis complex (MTBC) in broth culture media by using detonation nanodiamonds (DNDs) as a platform to effectively capture the antigen secreted by MTBC which is cultured in BACTEC MGIT 960, followed by the analysis of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS). The 5 nm DNDs can capture the MTBC secretory antigen without albumin interference. With on diamond digestion, we confirm the DND captured antigen is cell filtrate protein 10 (CFP-10) because its Mascot analysis shows a score of 68. The dot blotting method further verifies a positive reaction with anti-CFP-10, indicating that CFP-10 is secreted in the medium of mycobacterium growth indicator tube (MGIT) and captured by DNDs. The minimal CFP-10 protein detection limit was 0.09 μg/mL. Furthermore, our approach can avoid the false-positive identification of MTBC by immunological methods due to cross-reactivity. Five hundred consecutive clinical specimens subjected to routine mycobacteria identification in hospital were used in this study, and the sensitivity of our method is 100% and the specificity is 98%. The analysis of each MTBC sample from culture solution can be finished within 1 h and thus shortens the turnaround time of MTBC identification of gold standard culture methods. In sum, DND MALDI-TOF MS for the detection of MTBC is rapid, specific, safe, reliable, and inexpensive. PMID:22905748

  16. Stress in dilute suspensions

    NASA Technical Reports Server (NTRS)

    Passman, Stephen L.

    1989-01-01

    Generally, two types of theory are used to describe the field equations for suspensions. The so-called postulated equations are based on the kinetic theory of mixtures, which logically should give reasonable equations for solutions. The basis for the use of such theory for suspensions is tenuous, though it at least gives a logical path for mathematical arguments. It has the disadvantage that it leads to a system of equations which is underdetermined, in a sense that can be made precise. On the other hand, the so-called averaging theory starts with a determined system, but the very process of averaging renders the resulting system underdetermined. A third type of theory is proposed in which the kinetic theory of gases is used to motivate continuum equations for the suspended particles. This entails an interpretation of the stress in the particles that is different from the usual one. Classical theory is used to describe the motion of the suspending medium. The result is a determined system for a dilute suspension. Extension of the theory to more concentrated systems is discussed.

  17. A PRESSURIZED PROPORTIONAL DILUTER FOR AQUATIC TOXICOLOGICAL STUDIES

    EPA Science Inventory

    A half-liter proportional diluter using positive pressure was designed and tested. Its primary siphons are activated by a pulse of pressure instead of by a partial vacuum as in conventional diluters. This method eliminated the need for venturi tubes, vacuum manifolds, and individ...

  18. The inhibitory effect of natural microflora of food on growth of Listeria monocytogenes in enrichment broths.

    PubMed

    Al-Zeyara, Shaikha A; Jarvis, Basil; Mackey, Bernard M

    2011-01-31

    The aims of this study were to (i) compare the inhibitory effects of the natural microflora of different foods on the growth of Listeria monocytogenes during enrichment in selective and non-selective broths; (ii) to isolate and identify components of the microflora of the most inhibitory food; and (iii) to determine which of these components was most inhibitory to growth of L. monocytogenes in co-culture studies. Growth of an antibiotic-resistant marker strain of L. monocytogenes was examined during enrichment of a range of different foods in Tryptone Soya Broth (TSB), Half Fraser Broth (HFB) and Oxoid Novel Enrichment (ONE) Broth. Inhibition of L. monocytogenes was greatest in the presence of minced beef, salami and soft cheese and least with prepared fresh salad and chicken pâté. For any particular food the numbers of L. monocytogenes present after 24h enrichment in different broths increased in the order: TSB, HFB and ONE Broth. Numbers of L. monocytogenes recovered after enrichment in TSB were inversely related to the initial aerobic plate count (APC) in the food but with only a moderate coefficient of determination (R(2)) of 0.51 implying that microbial numbers and the composition of the microflora both influenced the degree of inhibition of L. monocytogenes. In HFB and ONE Broth the relationship between APC and final L. monocytogenes counts was weaker. The microflora of TSB after 24h enrichment of minced beef consisted of lactic acid bacteria, Brochothrix thermosphacta, Pseudomonas spp., Enterobacteriaceae, and enterococci. In co-culture studies of L. monocytogenes with different components of the microflora in TSB, the lactic acid bacteria were the most inhibitory followed by the Enterobacteriaceae. The least inhibitory organisms were Pseudomonas sp., enterococci and B. thermosphacta. In HFB and ONE Broth the growth of Gram-negative organisms was inhibited but lactic acid bacteria still reached high numbers after 24h. A more detailed study of the growth of

  19. Antimicrobial Activity of a Neem Cake Extract in a Broth Model Meat System

    PubMed Central

    Del Serrone, Paola; Nicoletti, Marcello

    2013-01-01

    This work reports on the antimicrobial activity of an ethyl acetate extract of neem (Azadirachta indica) cake (NCE) against bacteria affecting the quality of retail fresh meat in a broth model meat system. NCE (100 µg) was also tested by the agar disc diffusion method. It inhibited the growth of all tested microorganisms. The NCE growth inhibition zone (IZ) ranged 11.33–22.67 mm while the ciprofloxacin (10 µg) IZ ranged from 23.41–32.67 mm. There was no significant difference (p ≤ 0.05) between the antimicrobial activity of NCE and ciprofloxacin vs. C. jejuni and Leuconostoc spp. The NCE antibacterial activity was moreover determined at lower concentrations (1:10–1:100,000) in micro-assays. The percent growth reduction ranged from 61 ± 2.08–92 ± 3.21. The higher bacterial growth reduction was obtained at 10 µg concentration of NCE. Species-specific PCR and multiplex PCR with the DNA dye propidium monoazide were used to directly detect viable bacterial cells from experimentally contaminated meat samples. The numbers of bacterial cells never significantly (p ≤ 0.05) exceeded the inocula concentration used to experimentally contaminate the NCE treated meat. This report represents a screening methodology to evaluate the antimicrobial capability of a herbal extract to preserve meat. PMID:23917814

  20. Ergosterols from the Culture Broth of Marine Streptomyces anandii H41-59

    PubMed Central

    Zhang, Yang-Mei; Li, Hong-Yu; Hu, Chen; Sheng, Hui-Fan; Zhang, Ying; Lin, Bi-Run; Zhou, Guang-Xiong

    2016-01-01

    An actinomycete strain, H41-59, isolated from sea sediment in a mangrove district, was identified as Streptomyces anandii on the basis of 16S rDNA gene sequence analysis as well as the investigation of its morphological, physiological and biochemical characteristics. Three new ergosterols, ananstreps A–C (1–3), along with ten known ones (4–13), were isolated from the culture broth of this strain. The gross structures of these new compounds were elucidated on the basis of extensive analysis of spectroscopic data, including HR-ESI-MS, and NMR. The cytotoxicities of these isolates against human breast adenocarcinoma cell line MCF-7, human glioblastoma cell line SF-268, and human lung cancer cell line NCI-H460 and their antibacterial activities in inhibiting the growth of Candida albicans and some other pathogenic microorganisms were tested. Compounds 3–8, 10 and 11 displayed cytotoxicity with IC50 values in a range from 13.0 to 27.8 μg/mL. However, all the tested compounds showed no activity on C. albicans and other bacteria at the test concentration of 1 mg/mL with the paper disc diffusion method. PMID:27153073

  1. Ergosterols from the Culture Broth of Marine Streptomyces anandii H41-59.

    PubMed

    Zhang, Yang-Mei; Li, Hong-Yu; Hu, Chen; Sheng, Hui-Fan; Zhang, Ying; Lin, Bi-Run; Zhou, Guang-Xiong

    2016-01-01

    An actinomycete strain, H41-59, isolated from sea sediment in a mangrove district, was identified as Streptomyces anandii on the basis of 16S rDNA gene sequence analysis as well as the investigation of its morphological, physiological and biochemical characteristics. Three new ergosterols, ananstreps A-C (1-3), along with ten known ones (4-13), were isolated from the culture broth of this strain. The gross structures of these new compounds were elucidated on the basis of extensive analysis of spectroscopic data, including HR-ESI-MS, and NMR. The cytotoxicities of these isolates against human breast adenocarcinoma cell line MCF-7, human glioblastoma cell line SF-268, and human lung cancer cell line NCI-H460 and their antibacterial activities in inhibiting the growth of Candida albicans and some other pathogenic microorganisms were tested. Compounds 3-8, 10 and 11 displayed cytotoxicity with IC50 values in a range from 13.0 to 27.8 μg/mL. However, all the tested compounds showed no activity on C. albicans and other bacteria at the test concentration of 1 mg/mL with the paper disc diffusion method. PMID:27153073

  2. Biological evaluation of Phellinus linteus-fermented broths as anti-inflammatory agents.

    PubMed

    Lin, Chun-Jung; Lien, Hsiu-Man; Chang, Hsiao-Yun; Huang, Chao-Lu; Liu, Jau-Jin; Chang, Yun-Chieh; Chen, Chia-Chang; Lai, Chih-Ho

    2014-07-01

    Phellinus linteus and its constituent hispolon induce potent anti-inflammatory activity in macrophages. Efficient production of the effective constituent and the biological function of P. linteus in the regulation of innate sensing have rarely been investigated. The aim of this study was to efficiently manufacture P. linteus-fermented broth containing the effective constituent, hispolon, and evaluate its immunoregulatory functions in macrophages. Four distinct fermented broths (PL1-4) and the medium dialyzate (MD) were prepared to screen suitable culture conditions for the mycelial growth of P. linteus. The P. linteus-fermented broth exhibited a dose-responsive inhibition of lipopolysaccharide (LPS)-induced nitric oxide (NO) production by murine macrophages. In addition, the P. linteus-fermented broths suppressed macrophage LPS-mediated nuclear factor (NF)-κB activity and tumor necrosis factor (TNF)-α. Among the tested samples from P. linteus, PL4 contained vast amounts of hispolon and showed the greatest anti-inflammatory activity in both the RAW264.7 cells and murine primary peritoneal exudate macrophages (PEMs). This study demonstrates that the purification of the effective constituent from P. linteus-fermented broth may enable the production of a potent therapeutic agent for anti-inflammation in macrophages. PMID:24503424

  3. Evaluation of Trans-Vag Broth, Colistin-Nalidixic Agar, and CHROMagar StrepB for Detection of Group B Streptococcus in Vaginal and Rectal Swabs from Pregnant Women in South Africa

    PubMed Central

    Kwatra, Gaurav; Madhi, Shabir A.; Cutland, Clare L.; Buchmann, Eckhart J.

    2013-01-01

    Maternal vaginal colonization with group B streptococcus (GBS) is a major risk factor for invasive GBS infection in newborns. The CDC-recommended method for detecting GBS colonization is to culture vaginal and rectal swabs in a selective broth followed by subculture on blood agar or a selective medium. A high incidence of antimicrobial resistance in the fecal microflora can compromise the recovery of GBS from the selective broth. Here, we compared CHROMagar StrepB (CA), Columbia colistin-nalidixic agar (CNA), and Trans-Vag selective broth enrichment for the isolation of GBS from 130 vaginal and 130 rectal swabs from pregnant women. The swabs were randomized for plating first on either CA or CNA, and they then were inoculated in Trans-Vag broth. GBS was cultured from 37.7% of the vaginal swabs and 33.1% of the rectal swabs. There were no differences in the detection rates for the vaginal swabs between CA (31.5%), CNA (26.2%), and the selective broth (30.0%). The sensitivities in relation to a composite score were 83.7%, 69.4%, and 79.6%, respectively. However, recovery of GBS from the rectal swabs was significantly higher from CA (29.2%; P < 0.0001) and CNA (23.8%; P = 0.002) than from the selective broth (9.2%). The sensitivities were 88.4%, 72.1%, and 27.9%, respectively. The order of plating on the solid medium was significant (P = 0.003), with GBS detection rates of 30.8% and 24.6% when swabs were plated first and second, respectively. These findings show that a selective broth is not suitable for the recovery of GBS from rectal swabs in settings such as ours, due to masking of the GBS colonies by persistent microflora. PMID:23698527

  4. Nutrient Requirements of Renibacterium salmoninarum on Agar and in Broth Media.

    PubMed

    Daly, J G; Stevenson, R M

    1993-07-01

    In well-aerated broth cultures, good growth of Renibacterium salmoninarum was obtained in a serum-free medium consisting of 1% peptone, 1% yeast extract, and 0.1% l-cysteine (PYC broth). In contrast, serum or charcoal is required for growth on agar medium. Charcoal treatment of broth media, either before bacterial inoculation or during growth, increased the growth of R. salmoninarum, whereas the surfactants Tween 20 and Tween 80 inhibited growth. l-Cysteine was essential for optimal growth. Other organic sulfur compounds, such as d-cysteine, l-methionine, homocysteine, homocysteine thiolactone, and reduced glutathione, supported only lower levels of growth, while cystine and dithiothreitol did not allow growth. PMID:16348993

  5. Nutrient Requirements of Renibacterium salmoninarum on Agar and in Broth Media

    PubMed Central

    Daly, J. G.; Stevenson, R. M. W.

    1993-01-01

    In well-aerated broth cultures, good growth of Renibacterium salmoninarum was obtained in a serum-free medium consisting of 1% peptone, 1% yeast extract, and 0.1% l-cysteine (PYC broth). In contrast, serum or charcoal is required for growth on agar medium. Charcoal treatment of broth media, either before bacterial inoculation or during growth, increased the growth of R. salmoninarum, whereas the surfactants Tween 20 and Tween 80 inhibited growth. l-Cysteine was essential for optimal growth. Other organic sulfur compounds, such as d-cysteine, l-methionine, homocysteine, homocysteine thiolactone, and reduced glutathione, supported only lower levels of growth, while cystine and dithiothreitol did not allow growth. PMID:16348993

  6. Distribution of the hallucinogens N,N-dimethyltryptamine and 5-methoxy-N,N-dimethyltryptamine in rat brain following intraperitoneal injection: application of a new solid-phase extraction LC-APcI-MS-MS-isotope dilution method.

    PubMed

    Barker, S A; Littlefield-Chabaud, M A; David, C

    2001-02-10

    A method for the solid-phase extraction (SPE) and liquid chromatographic-atmospheric pressure chemical ionization-mass spectrometric-mass spectrometric-isotope dilution (LC-APcI-MS-MS-ID) analysis of the indole hallucinogens N,N-dimethyltryptamine (DMT) and 5-methoxy DMT (or O-methyl bufotenin, OMB) from rat brain tissue is reported. Rats were administered DMT or OMB by the intraperitoneal route at a dose of 5 mg/kg and sacrificed 15 min post treatment. Brains were dissected into discrete areas and analyzed by the methods described as a demonstration of the procedure's applicability. The synthesis and use of two new deuterated internal standards for these purposes are also reported. PMID:11232854

  7. Dilution refrigeration for space applications

    NASA Technical Reports Server (NTRS)

    Israelsson, U. E.; Petrac, D.

    1990-01-01

    Dilution refrigerators are presently used routinely in ground based applications where temperatures below 0.3 K are required. The operation of a conventional dilution refrigerator depends critically on the presence of gravity. To operate a dilution refrigerator in space many technical difficulties must be overcome. Some of the anticipated difficulties are identified in this paper and possible solutions are described. A single cycle refrigerator is described conceptually that uses forces other than gravity to function and the stringent constraints imposed on the design by requiring the refrigerator to function on the earth without using gravity are elaborated upon.

  8. [Effective Prevention of Hand-Foot Syndrome by the Consumption of Dried Bonito Broth].

    PubMed

    Kamimura, Kenya; Shinagawa, Yoko; Ogawa, Kohei; Kobayashi, Yuji; Abe, Hiroyuki; Yokoo, Takeshi; Kamimura, Hiroteru; Kawai, Hirokazu; Suda, Takeshi; Yamagiwa, Satoshi; Baba, Hiroshi; Terai, Shuji

    2016-04-01

    To examine whether the consumption of dried bonito both is effective for the prevention of hand-foot syndrome(HFS), concentrated bonito broth was administered to 10 patients with HCC who were treated with sorafenib. Among the 10 patients, seven showed an increase in peripheral blood flow, as observed on Doppler ultrasonography. Only one patient showed Grade 1 HFS on day 14 after the initiation of sorafenib (10%); this incidence rate of HFS was significantly lower than that obtained in our previous studies and reported data. These results suggest that consumption of dried bonito broth contributes to the prevention of HFS by maintaining peripheral blood flow. PMID:27220795

  9. Comparison of the Cathra Repliscan II, the AutoMicrobic system Gram-Negative General Susceptibility-Plus Card, and the Micro-Media System Fox Panel for dilution susceptibility testing of gram-negative bacilli.

    PubMed

    Reiber, N E; Kelly, M T; Latimer, J M; Tison, D L; Hysmith, R M

    1985-06-01

    A comparative evaluation was done to test the accuracy of the Cathra Repliscan II agar dilution system (Diagnostic Equipment, Inc., St. Paul, Minn.), the AutoMicrobic system with Gram-Negative General Susceptibility-Plus Card (Vitek Systems, Inc., Hazelwood, Mo.), and the Micro-Media Fox Panel micro broth dilution system (Micro-Media Systems, Inc., San Jose, Calif.) in determining MICs of 12 antibiotics for 200 gram-negative bacilli. Of the 200 strains tested, 12 isolates did not grow in one of the three systems. The 188 remaining organisms included 158 members of the family Enterobacteriaceae, 20 Pseudomonas spp., 5 Acinetobacter sp., 3 Aeromonas spp., and 2 Vibrio spp. A total of 2,256 organism-antibiotic combinations were analyzed for each system. An MIC was considered correct if two of the three systems were in agreement. When disagreements occurred, correct MICs were determined by the standard agar dilution method. With this criterion, overall agreements of the Cathra Repliscan II system, AutoMicrobic system, and Micro-Media Fox Panel system were 94.7, 94.9, and 95.5%, respectively. Tetracycline (20%), nitrofurantoin (20%), and ampicillin (16%) accounted for 56% of the discrepancies observed. These results indicate that all three systems perform with a high degree of accuracy for susceptibility testing of gram-negative bacilli. PMID:4008625

  10. Intermittency in dilute granular flows

    NASA Astrophysics Data System (ADS)

    Guo, Wenxuan; Zhang, Qiang; Wylie, Jonathan J.

    2016-07-01

    In this letter, we show that dilute granular systems can exhibit a type of intermittency that has no analogue in gas dynamics. We consider a simple system in which a very dilute set of granular particles falls under gravity through a nozzle. This setting is analogous to the classical problem of high-speed nozzle flow in the study of compressible gases. It is well known that very dilute granular systems exhibit behavior qualitatively similar to gases, and that gas flowing through a nozzle does not exhibit intermittency. Nevertheless, we show that the intermittency in dilute granular nozzle flows can occur and corresponds to complicated transitions between supersonic and subsonic regimes. We also provide detailed explanations of the mechanism underlying this phenomenon.

  11. One-step isolation of adenosine triphosphate from crude fermentation broth of Saccharomyces cerevisiae by anion-exchange chromatography using supermacroporous cryogel.

    PubMed

    Yun, Junxian; Shen, Shaochuan; Chen, Fang; Yao, Kejian

    2007-12-01

    Adenosine triphosphate (ATP) is an important high-energy compound widely used in biological and therapeutic fields. It can be produced by phosphorylation of adenosine monophosphate (AMP) with microbial cells in industrial scale and the effective isolation of ATP from microbial fermentation broth is a challenging work. In this work, we develop a novel one-step method to directly separate ATP from fermentation broth of Saccharomyces cerevisiae by anion-exchange chromatography using supermacroporous cryogel. The cryogel bed with tertiary amine groups was prepared by grafting N,N-dimethylaminoethyl methacrylate (DMAEMA) monomer chains onto the matrix of a polyacrylamide-based cryogel in a glass column and its properties of liquid dispersion, water permeability, porosity as well as the ligand density were measured. Chromatographic separation of ATP from the fermentation broth by the cryogel was carried out using deionised water and 0.01 M HCl as running buffer, respectively. The breakthrough characteristics and elution performance in the cryogel bed were revealed and analyzed. The purities of the obtained ATP were analyzed quantitatively by high performance liquid chromatography (HPLC). The maximal purity of ATP by the one-step separation method was 95.5% using 0.01 M HCl as running buffer in this work. The corresponding chromatographic behaviors were investigated and analyzed. PMID:18024244

  12. Dilute nanoemulsions via separation of satellite droplets.

    PubMed

    Deen, Shad; Sajjadi, Shahriar

    2013-10-01

    A facile method is suggested for fabrication of dilute nanoemulsions. In a typical emulsification process, drops are usually accompanied by off-grade satellite droplets. The size of these satellite droplets ranges from hundreds of nanometers to above microns. Experiments were carried out to assess the possibility of separation of nanodrops from macroemulsions made via a conventional method in order to produce nanoemulsions. A low-power homogenizer was used to produce parent emulsions which were then injected from the bottom to a glass column containing water and allowed to cream. By monitoring drops remaining in the bottom of the column, it is clearly shown how progressively smaller they become with time yielding eventually dilute nanoemulsions. The average diameter of drops reduced to 100 nm when oil with high viscosity was used. The concentration of resulting nanoemulsions increased with increasing viscosity and ratio of the disperse phase of parent emulsions. PMID:23830283

  13. Development of a multi-pathogen enrichment broth for simultaneous growth of five common foodborne pathogens.

    PubMed

    Chen, Juan; Tang, Junni; Bhunia, Arun K; Tang, Cheng; Wang, Changting; Shi, Hui

    2015-01-01

    The objective of the present study was to formulate a multi-pathogen enrichment broth which could support the simultaneous growth of five common foodborne pathogens (Salmonella enterica, Staphylococcus aureus, Shigella flexneri, Listeria monocytogenes and Escherichia coli O157:H7). The formulated broth SSSLE was composed of potassium tellurite, bile salt, lithium chloride, and sodium chloride as growth-inhibitors; glucose, esculin, mannitol and sodium pyruvate as growth-promoters. Compared with the respective specific selective enrichment broths, the individual growth pattern of each target pathogen in SSSLE was equal, or even better, except in the case of S. flexneri. In mixed-culture experiments, the gram-negative bacteria showed higher growth capabilities than the gram-positive bacteria after 8-h enrichment; however, the cell numbers after 24-h enrichment indicated that SSSLE could support the concurrent growth of five target pathogens irrespective of whether pathogens were inoculated initially at equal or unequal levels. For natural food samples under the high background flora, the final cell numbers enriched in SSSLE for five targets were enough to be detected by multiplex PCR. In conclusion, SSSLE was capable of supporting the growth of five target pathogens concurrently. The new broth formulated in this study has the potential of saving time, efforts and costs in multi-pathogen enrichment procedures. PMID:26782652

  14. Evaluation of a newly developed triple buffered peptone broth for detection of Salmonella in broiler feed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lactose broth (LB) and buffered peptone (BP) are used as pre-enrichment media to recover Salmonella from feed. Bacterial utilization of feed carbohydrates results in the production of acidic byproducts causing a drop in the media pH which can injure or kill Salmonella and yield false negative resul...

  15. Enrichment culture for the isolation of Campylobacter spp: Effects of incubation conditions and the inclusion of blood in selective broths.

    PubMed

    Williams, Lisa K; Jørgensen, Frieda; Grogono-Thomas, Rose; Humphrey, Tom J

    2009-03-31

    Isolation of Campylobacter spp. using enrichment culture is time consuming and complex. Reducing the time taken to confirm the presence or absence of Campylobacter spp. would have many advantages for diagnostic, commercial and research applications. Rapid techniques such as real-time PCR can detect campylobacters from complex samples but blood in enrichment culture can inhibit the PCR reaction, if applied directly to enriched samples. The aim of this study was to investigate the effect of blood in enrichment culture on the isolation of campylobacters from chicken caeca, carcass rinses and bootsock (gauze sock walked through a broiler chicken house) samples using Bolton broth. The effect of incubation temperature (37 degrees C or 41.5 degrees C for 48 h, or 37 degrees C for 4 h then transfer to 41.5 degrees C for 44 h) and method of generating atmosphere (incubation of container in jar gassed with microaerobic atmosphere or incubation of container with small headspace and tightly screwed lid in an aerobic atmosphere) with and without blood on isolation from chicken carcass rinses and chicken faeces was also investigated. The presence of blood in enrichment culture did not improve the isolation of campylobacters from chicken faeces or bootsock samples but significantly improved recovery from chicken carcass rinse samples. There was no significant effect of the method used to generate incubation atmosphere. Isolation rates did also not depend significantly on whether broths were incubated at 37 or 41.5 degrees C for 24 or 48 h. Overall, the presence of blood in such media is not essential, although isolation can vary depending on sample type and enrichment method used. PMID:19217181

  16. Partial purification of saccharifying and cell wall-hydrolyzing enzymes from malt in waste from beer fermentation broth.

    PubMed

    Khattak, Waleed Ahmad; Kang, Minkyung; Ul-Islam, Mazhar; Park, Joong Kon

    2013-06-01

    A number of hydrolyzing enzymes that are secreted from malt during brewing, including cell wall-hydrolyzing, saccharide-hydrolyzing, protein-degrading, lipid-hydrolyzing, and polyphenol and thiol-hydrolyzing enzymes, are expected to exist in an active form in waste from beer fermentation broth (WBFB). In this study, the existence of these enzymes was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis, after which enzyme extract was partially purified through a series of purification steps. The hydrolyzing enzyme activity was then measured under various conditions at each purification step using carboxymethyl cellulose as a substrate. The best hydrolyzing activities of partially purified enzymes were found at pH 4.5 and 50 °C in a citrate buffer system. The enzymes showed highest thermal stability at 30 °C when exposed for prolonged time. As the temperature increased gradually from 25 to 70 °C, yeast cells in the chemically defined medium with enzyme extract lost their cell wall and viability earlier than those without enzyme extract. Cell wall degradation and the release of cell matrix into the culture media at elevated temperature (45-70 °C) in the presence of enzyme extract were monitored through microscopic pictures. Saccharification enzymes from malt were relatively more active in the original WBFB than supernatant and diluted sediments. The presence of hydrolyzing enzymes from malt in WBFB is expected to play a role in bioethanol production using simultaneous saccharification and fermentation without the need for additional enzymes, nutrients, or microbial cells via a cell-free enzyme system. PMID:23377262

  17. Quality control guidelines for disk diffusion and broth microdilution antimicrobial susceptibility tests with seven drugs for veterinary applications.

    PubMed

    Odland, B A; Erwin, M E; Jones, R N

    2000-01-01

    This multicenter study proposes antimicrobial susceptibility (MIC and disk diffusion methods) quality control (QC) parameters for seven compounds utilized in veterinary health. Alexomycin, apramycin, tiamulin, tilmicosin, and tylosin were tested by broth microdilution against various National Committee for Clinical Laboratory Standards (NCCLS)-recommended QC organisms (Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212, Streptococcus pneumoniae ATCC 49619, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 27853). In addition, disk diffusion zone diameter QC limits were determined for apramycin, enrofloxacin, and premafloxacin by using E. coli ATCC 25922, P. aeruginosa ATCC 27853, and S. aureus ATCC 25923. The results from five or six participating laboratories produced >/=99.0% of MICs and >/=95.0% of the zone diameters within suggested guidelines. The NCCLS Subcommittee for Veterinary Antimicrobial Susceptibility Testing has recently approved these ranges for publication in the next M31 document. PMID:10618141

  18. Detection of Salmonellae in Chicken Feces by a Combination of Tetrathionate Broth Enrichment, Capillary PCR, and Capillary Gel Electrophoresis

    PubMed Central

    Carli, K. Tayfun; Unal, Can Bora; Caner, Vildan; Eyigor, Aysegul

    2001-01-01

    This report describes a rapid detection procedure for salmonellae from chicken feces by the combination of tetrathionate primary enrichment (preenrichment [PE])-bacterial lysis-capillary PCR and capillary gel electrophoresis. Pure Salmonella enterica serovar Enteritidis 64K was reisolated and detected by capillary PCR after buffered peptone water and nutrient broth, tetrathionate broth base Hajna (TTBH), and tetrathionate broth (TTB) preenrichments. When the same culture was mixed with intestinal homogenate, bacteriological reisolation and capillary PCR detection was achieved only by TTBH and TTB preenrichments. Capillary gel electrophoresis revealed that a Salmonella genus-specific 281-bp PCR product was detected when Salmonella strains but not non-Salmonella strains were tested. The detection limit of capillary PCR with whole-cell DNA extracted from pure Salmonella enterica serovars Enteritidis 64K, Typhimurium LT2-CIP60-62, and Gallinarum 64K was 3, 3, and 9 CFU ml−1, respectively. The detection limit of capillary PCR from whole-cell DNA extracted from intestinal homogenate artificially contaminated with the same three strains was 3, 3, and 7 CFU ml−1, respectively. We compared the results of the capillary PCR and bacteriological examination from the natural samples. Thirty-five of 53 naturally contaminated samples produced a specific PCR product. In 9 of the 35 PCR-positive samples, Salmonella could not be detected bacteriologically either by PE or a primary and delayed secondary enrichment (DSE) combination. In the 18 PCR-negative samples, 4 samples were found to harbor Salmonella by both PE and DSE and 14 samples were positive after DSE. Fifty-three additional intestinal homogenate samples, which were negative by their PE and DSE in bacteriological examination, were found to be also negative by their PCRs. The total time required to detect Salmonella with the capillary PCR method we used was approximately 20 h. If samples are from clinically diseased

  19. Effective control of Listeria monocytogenes by combination of nisin formulated and slowly released into a broth system.

    PubMed

    Chi-Zhang, Yundong; Yam, Kit L; Chikindas, Michael L

    2004-01-01

    In order to identify conditions for efficient food preservation by nisin, the sensitivity of Listeria monocytogenes to this preservative was studied under the following three model conditions: (1) the instantaneous addition of nisin into broth medium to simulate the formation of nisin in foods, (2) the slow delivery of nisin solution into broth medium using a pump to simulate the slow release of nisin from packaging materials to foods, (3) a combination of the two delivery methods. Based on the following results, we conclude that the antimicrobial effectiveness of nisin strongly depends on its mode of delivery. The instantaneous and slow methods for adding nisin inhibited L. monocytogenes, but over time of exposure, L. monocytogenes developed tolerance to nisin. Our data indicate that cells treated with instantaneously added nisin developed resistance to higher concentrations of nisin (200 IU/ml), compared to cells treated with slowly added nisin at the same total amount of the antimicrobial. Further studies indicated that nisin-tolerant cells recovered from treatments in which 200 IU/ml nisin was added instantaneously were likely to be mutants, which became resistant to the bacteriocin. In contrast, when 200 IU/ml of the antimicrobial was added slowly to the cells, only a temporary tolerance was developed; these cells became nisin-sensitive after passage through nisin-free medium. Due to the development of nisin-resistant cells, excessive amounts of nisin in the model system did not further inhibit L. monocytogenes. These results signify that excess nisin in foods does not necessarily improve the efficiency of controlling L. monocytogenes. Our data suggest that the combination of packaging material containing nisin used in conjunction with nisin-containing foods will provide the most effective means of preventing L. monocytogenes growth. PMID:14672827

  20. A simple one pot purification of bacterial amylase from fermented broth based on affinity toward starch-functionalized magnetic nanoparticle.

    PubMed

    Paul, Tanima; Chatterjee, Saptarshi; Bandyopadhyay, Arghya; Chattopadhyay, Dwiptirtha; Basu, Semanti; Sarkar, Keka

    2015-08-18

    Surface-functionalized adsorbant particles in combination with magnetic separation techniques have received considerable attention in recent years. Selective manipulation on such magnetic nanoparticles permits separation with high affinity in the presence of other suspended solids. Amylase is used extensively in food and allied industries. Purification of amylase from bacterial sources is a matter of concern because most of the industrial need for amylase is met by microbial sources. Here we report a simple, cost-effective, one-pot purification technique for bacterial amylase directly from fermented broth of Bacillus megaterium utilizing starch-coated superparamagnetic iron oxide nanoparticles (SPION). SPION was prepared by co-precipitation method and then functionalized by starch coating. The synthesized nanoparticles were characterized by transmission electron microscopy (TEM), a superconducting quantum interference device (SQUID, zeta potential, and ultraviolet-visible (UV-vis) and Fourier-transform infrared (FTIR) spectroscopy. The starch-coated nanoparticles efficiently purified amylase from bacterial fermented broth with 93.22% recovery and 12.57-fold purification. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) revealed that the molecular mass of the purified amylase was 67 kD, and native gel showed the retention of amylase activity even after purification. Optimum pH and temperature of the purified amylase were 7 and 50°C, respectively, and it was stable over a range of 20°C to 50°C. Hence, an improved one-pot bacterial amylase purification method was developed using starch-coated SPION. PMID:24840788

  1. Simultaneous Quantification of Methylated Cytidine and Adenosine in Cellular and Tissue RNA by Nano-Flow Liquid Chromatography-Tandem Mass Spectrometry Coupled with the Stable Isotope-dilution Method

    PubMed Central

    Fu, Lijuan; Amato, Nicolas J.; Wang, Pengcheng; McGowan, Sara J.; Niedernhofer, Laura J.; Wang, Yinsheng

    2016-01-01

    The rising interest in understanding the functions, regulation and maintenance of the epitranscriptome calls for robust and accurate analytical methods for the identification and quantification of post-transcriptionally modified nucleosides in RNA. Mono-methylations of cytidine and adenosine are common post-transcriptional modifications in RNA. Herein, we developed an LC-MS/MS/MS coupled with the stable isotope-dilution method for the sensitive and accurate quantifications of 5-methylcytidine (m5C), 2′-O-methylcytidine (Cm), N6-methyladenosine (m6A) and 2′-O-methyladenosine (Am) in RNA isolated from mammalian cells and tissues. Our results showed that the distributions of the four methylated nucleosides are tissue-specific. In addition, the 2′-O-methylated ribonucleosides (Cm and Am) are present at higher levels than the corresponding methylated nucleobase products (m5C and m6A) in total RNA isolated from mouse brain, pancreas and spleen, but not mouse heart. We also found that the levels of m5C, Cm and Am are significantly lower (by 6.5-43 fold) in mRNA than in total RNA isolated from HEK293T cells, whereas the level of m6A was slightly higher (by 1.6 fold) in mRNA than in total RNA. The availability of this analytical method, in combination with genetic manipulation, may facilitate the future discovery of proteins involved in the maintenance and regulation of these RNA modifications. PMID:26158405

  2. Development and validation of a new analytical method for the determination of 1,4-dichlorobenzene in honey by gas chromatography-isotope dilution mass spectrometry after steam-distillation.

    PubMed

    Botitsi, E V; Kormali, P N; Kontou, S N; Economou, A; Tsipi, D F

    2006-10-01

    A simple, fast, sensitive and robust analytical method using gas chromatography (GC)-isotope dilution mass spectrometry (MS) was developed and validated for the identification and quantification of 1,4-dichlorobenzene (p-DCB) residues in honey samples. The proposed methodology is based on steam-distillation using a Clevenger-type apparatus followed by gas chromatography-mass spectrometry (GC-MS) in the selected ion monitoring (SIM) mode employing the isotopically labeled analogue d4-1,4-dichlorobenzene (d4-p-DCB) as internal standard (IS). Validation of the method was performed in two different GC-MS systems, using quadrupole MS (QMS) and ion-trap MS (ITMS) detectors, with no statistically significant differences between two. Recoveries were better than 91% with percent relative standard deviations lower than 12%. The instrumental limits of detection were 1 microg kg(-1) in the GC-ITMS system and 0.6 microg kg(-1) in the GC-QMS system. The expanded uncertainty was estimated as 17% at the currently accepted "action level" of 10 microg kg(-1). The method was applied to the analysis of 310 honey samples in an extensive national monitoring study. A quality control (QC) system applied during the assays has demonstrated a good performance and long-term stability over a period of more than 8 months of continuous operation. PMID:17723727

  3. An eco-friendly strategy, using on-line monitoring and dilution coupled to a second-order chemometric method, for the construction of dissolution curves of combined pharmaceutical associations.

    PubMed

    Calvo, Natalia L; Maggio, Rubén M; Kaufman, Teodoro S

    2014-02-01

    A simple, precise, economic and minimally operator-dependent method was developed under green analytical chemistry principles, for the simultaneous construction of the dissolution curves of a pharmaceutical association in short time and without employing organic solvents, allowing important savings of labor and resources. The carvedilol (CAR) and hydrochlorothiazide (HCT) combined formulation was employed as a model. The method (OD/UV-MCR) involves on-line sample dilution (OD) and UV detection of the analytes, coupled to multivariate curve resolution with alternating least squares (MCR-ALS). OD/UV-MCR proved to be robust and was successfully validated in accordance to ICH guidelines, fulfilling acceptance criteria for specificity (r(2) of spectral correlation>0.950), linearity [r>0.999 (N=25) in the ranges 1.00-31.1mg l(-1) and 0.51-15.2mg l(-1) for CAR and HCT, respectively] and precision (RSD<2%). Accuracy was assessed by point-to-point comparison between the dissolution profiles furnished by the proposed method with those provided by HPLC analysis, evidencing the usefulness of this monitoring system. In addition, OD/UV-MCR was successfully employed for the comparative analysis of three lots of commercial formulations of the CAR-HCT pharmaceutical association, belonging to a couple of different brands, employing Moore and Flanner's f2 similarity indicator. PMID:24291800

  4. Structural and Optical properties of Er doped ZnO diluted magnetic semiconductor nano thin films produced by sol gel method

    NASA Astrophysics Data System (ADS)

    Tasci, A. Tolga; Ozturk, Ozgur; Asikuzun, Elif; Arda, Lutfi; Celik, Sukru; Terzioglu, Cabir

    Undoped and Er doped ZnO (Zn1-xErxO) transparent semiconductor thin films were coated using sol-gel method on non-alkali glass. Erbium was doped 1%, 2%, 3%, 4% and 5% ratio. Methanol and monoethanolamine were used as solvent and stabilizer. In this study, the effect of Er doping was examined on the structural and optical properties of ZnO DMS thin films. XRD, SEM and UV-VIS-NIR spectrometer measurements were performed for the structural and optical characterization. XRD results showed that, all of Er doped ZnO thin films have a hexagonal structure. The optical transmittance of rare earth element (Er) doped ZnO thin films were increased. The Er doped ZnO thin films showed high transparency (>84) in the visible region (400-700 nm). This research has been supported by the Kastamonu University Scientific Research Projects Coordination Department under the Grant No. KUBAP-03/2013-41 and the Scientific and Technological Research Council of Turkey (TUBITAK) Project No. 114F259.

  5. Nanofiltration, bipolar electrodialysis and reactive extraction hybrid system for separation of fumaric acid from fermentation broth.

    PubMed

    Prochaska, Krystyna; Staszak, Katarzyna; Woźniak-Budych, Marta Joanna; Regel-Rosocka, Magdalena; Adamczak, Michalina; Wiśniewski, Maciej; Staniewski, Jacek

    2014-09-01

    A novel approach based on a hybrid system allowing nanofiltration, bipolar electrodialysis and reactive extraction, was proposed to remove fumaric acid from fermentation broth left after bioconversion of glycerol. The fumaric salts can be concentrated in the nanofiltration process to a high yield (80-95% depending on pressure), fumaric acid can be selectively separated from other fermentation components, as well as sodium fumarate can be conversed into the acid form in bipolar electrodialysis process (stack consists of bipolar and anion-exchange membranes). Reactive extraction with quaternary ammonium chloride (Aliquat 336) or alkylphosphine oxides (Cyanex 923) solutions (yield between 60% and 98%) was applied as the final step for fumaric acid recovery from aqueous streams after the membrane techniques. The hybrid system permitting nanofiltration, bipolar electrodialysis and reactive extraction was found effective for recovery of fumaric acid from the fermentation broth. PMID:24983693

  6. Impact of boiling conditions on the molecular and sensory profile of a vegetable broth.

    PubMed

    Mougin, Alice; Mauroux, Olivier; Matthey-Doret, Walter; Barcos, Eugenia Maria; Beaud, Fernand; Bousbaine, Ahmed; Viton, Florian; Smarrito-Menozzi, Candice

    2015-02-11

    Low-pressure cooking has recently been identified as an alternative to ambient and high-pressure cooking to provide food with enhanced organoleptic properties. This work investigates the impact of the cooking process at different pressures on the molecular and sensory profile of a vegetable broth. Experimental results showed similar sensory and chemical profiles of vegetable broths when boiling at 0.93 and 1.5 bar, while an enhancement of sulfur volatile compounds correlated with a greater leek content and savory aroma was observed when boiling at low pressure (80 °C/0.48 bar). Thus, low-pressure cooking would allow preserving the most labile volatiles likely due to the lower water boiling temperature and the reduced level of oxygen. This study evidenced chemical and sensory impact of pressure during cooking and demonstrated that the flavor profile of culinary preparations can be enhanced by applying low-pressure conditions. PMID:25579390

  7. Quantification of oxidative DNA lesions in tissues of Long-Evans Cinnamon rats by capillary high-performance liquid chromatography-tandem mass spectrometry coupled with stable isotope-dilution method.

    PubMed

    Wang, Jin; Yuan, Bifeng; Guerrero, Candace; Bahde, Ralf; Gupta, Sanjeev; Wang, Yinsheng

    2011-03-15

    The purpose of our study was to develop suitable methods to quantify oxidative DNA lesions in the setting of transition metal-related diseases. Transition metal-driven Fenton reactions constitute an important endogenous source of reactive oxygen species (ROS). In genetic diseases with accumulation of transition metal ions, excessive ROS production causes pathophysiological changes, including DNA damage. Wilson's disease is an autosomal recessive disorder with copper toxicosis due to deficiency of ATP7B protein needed for excreting copper into bile. The Long-Evans Cinnamon (LEC) rat bears a deletion in Atp7b gene and serves as an excellent model for hepatic Wilson's disease. We used a sensitive capillary liquid chromatography-electrospray-tandem mass spectrometry (LC-ESI-MS/MS/MS) method in conjunction with the stable isotope-dilution technique to quantify several types of oxidative DNA lesions in the liver and brain of LEC rats. These lesions included 5-formyl-2'-deoxyuridine, 5-hydroxymethyl-2'-deoxyuridine, and the 5'R and 5'S diastereomers of 8,5'-cyclo-2'-deoxyguanosine and 8,5'-cyclo-2'-deoxyadenosine. Moreover, the levels of these DNA lesions in the liver and brain increased with age and correlated with age-dependent regulation of the expression of DNA repair genes in LEC rats. These results provide significant new knowledge for better understanding the implications of oxidative DNA lesions in transition metal-induced diseases, such as Wilson's disease, as well as in aging and aging-related pathological conditions. PMID:21323344

  8. Expression of food-grade phytase in Lactococcus lactis from optimized conditions in milk broth.

    PubMed

    Miao, Yuzhi; Xu, Hui; Fei, Baojin; Qiao, Dairong; Cao, Yi

    2013-07-01

    The major objective of this study was to engineer lactic acid bacteria to produce the enzyme phytase from a gene native to Bacillus subtilis GYPB04. The phytase gene (phyC) of B. subtilis GYPB04 was cloned into the plasmid pMG36e for expression in Lactococcus lactis. The enzyme activity in L. lactis cultured in GM17 broth was 20.25 U/mL at 36°C. The expressed phytase was characterized as active in a pH range of 2.0-9.0 at a temperature range of 20-80°C, with an optimum pH of 5.5-6.5 and temperature of 60°C. When cultured in food-grade milk broth, the transformed L. lactis grew to an OD(600 nm) value of 1.05 and had a phytase yield of 13.58 U/mL. In same broth under optimized conditions for cell growth and phytase production, the transformant reached an OD(600 nm) value of 1.68 and a phytase yield of 42.12 U/mL, representing approximately 1.6-fold and 3.1-fold increases, respectively, compared to growth in natural milk broth. Fermentation was scaled to 5 L under optimized conditions, and product analysis revealed a final OD(600 nm) value of 1.89 and an extracellular enzyme activity of 24.23 U/mL. The results of this study may be used in the dairy fermentation industry for the development of functional, healthy yogurts and other fermented dairy foods that provide both active phytase and viable probiotics to the consumer. PMID:23453854

  9. UV-Heat Treatments for the Control of Foodborne Microbial Pathogens in Chicken Broth.

    PubMed

    Gouma, M; Gayán, E; Raso, J; Condón, S; Álvarez, I

    2015-01-01

    This investigation established the process criteria for using UV-C light and mild heat (UV-H treatment) to inactivate 5-Log10 cycles (performance criterion) of common foodborne pathogen populations, Escherichia coli, Salmonella Typhimurium, Listeria monocytogenes, and Staphylococcus aureus, when inoculated in chicken broth. To define the target microorganism and the proper UV-H treatment conditions (including UV dose, treatment time, and temperature) that would achieve the stated performance criterion, mathematical equations based on Geeraerd's model were developed for each microorganism. For the sake of comparison, inactivation equations for heat treatments were also performed on the same chicken broth and for the same microorganisms. L. monocytogenes was the most UV-H resistant microorganism at all temperatures, requiring a UV dose between 6.10 J/mL (5.6 min) and 2.26 J/mL (2.09 min) to achieve 5-Log10 reductions. In comparison with UV treatments at room temperatures, the combination of UV and mild heat allowed both the UV dose and treatment time to be reduced by 30% and 63% at 55 °C and 60 °C, respectively. Compared to heat treatments, the UV-H process reduced the heating time for 5-Log10 reductions of all the investigated microorganisms in chicken broth from 20-fold to 2-fold when the operating temperature varied from 53 to 60 °C. PMID:26539493

  10. UV-Heat Treatments for the Control of Foodborne Microbial Pathogens in Chicken Broth

    PubMed Central

    Gouma, M.; Gayán, E.; Raso, J.; Condón, S.; Álvarez, I.

    2015-01-01

    This investigation established the process criteria for using UV-C light and mild heat (UV-H treatment) to inactivate 5-Log10 cycles (performance criterion) of common foodborne pathogen populations, Escherichia coli, Salmonella Typhimurium, Listeria monocytogenes, and Staphylococcus aureus, when inoculated in chicken broth. To define the target microorganism and the proper UV-H treatment conditions (including UV dose, treatment time, and temperature) that would achieve the stated performance criterion, mathematical equations based on Geeraerd's model were developed for each microorganism. For the sake of comparison, inactivation equations for heat treatments were also performed on the same chicken broth and for the same microorganisms. L. monocytogenes was the most UV-H resistant microorganism at all temperatures, requiring a UV dose between 6.10 J/mL (5.6 min) and 2.26 J/mL (2.09 min) to achieve 5-Log10 reductions. In comparison with UV treatments at room temperatures, the combination of UV and mild heat allowed both the UV dose and treatment time to be reduced by 30% and 63% at 55°C and 60°C, respectively. Compared to heat treatments, the UV-H process reduced the heating time for 5-Log10 reductions of all the investigated microorganisms in chicken broth from 20-fold to 2-fold when the operating temperature varied from 53 to 60°C. PMID:26539493

  11. A Chlorhexidine- Agar Plate Culture Medium Protocol to Complement Standard Broth Culture of Mycobacterium tuberculosis

    PubMed Central

    Asmar, Shady; Chatellier, Sonia; Mirande, Caroline; van Belkum, Alex; Canard, Isabelle; Raoult, Didier; Drancourt, Michel

    2016-01-01

    The culture of Mycobacterium tuberculosis using parallel inoculation of a solid culture medium and a liquid broth provides the gold standard for the diagnosis of tuberculosis. Here, we evaluated a chlorhexidine decontamination-MOD9 solid medium protocol versus the standard NALC-NaOH-Bactec 960 MGIT protocol for the diagnosis of pulmonary tuberculosis by culture. Three-hundred clinical specimens comprising 193 sputa, 30 bronchial aspirates, 10 broncho-alveolar lavages, 47 stools, and 20 urines were prospectively submitted for the routine diagnosis of tuberculosis. The contamination rates were 5/300 (1.7%) using the MOD9 protocol and 17/300 (5.7%) with the Bactec protocol, respectively (P < 0.05, Fisher exact test). Of a total of 50 Mycobacterium isolates (48 M. tuberculosis and two Mycobacterium abscessus) were cultured. Out of these 50, 48 (96%) isolates were found using the MOD9 protocol versus 35 (70%) when using the Bactec protocol (P < 0.05, Fisher exact test). The time to positivity was 10.1 ± 3.9 days versus 14.7 ± 7.3 days, respectively, (P < 0.05, Student’s t-test). These data confirmed the usefulness of parallel inoculation of a solid culture medium with broth for the recovery of M. tuberculosis in agreement with current recommendations. More specifically, chlorhexidine decontamination and inoculation of the MOD9 solid medium could be proposed to complement the standard Bactec 960 MGIT broth protocol. PMID:26834733

  12. A Chlorhexidine- Agar Plate Culture Medium Protocol to Complement Standard Broth Culture of Mycobacterium tuberculosis.

    PubMed

    Asmar, Shady; Chatellier, Sonia; Mirande, Caroline; van Belkum, Alex; Canard, Isabelle; Raoult, Didier; Drancourt, Michel

    2016-01-01

    The culture of Mycobacterium tuberculosis using parallel inoculation of a solid culture medium and a liquid broth provides the gold standard for the diagnosis of tuberculosis. Here, we evaluated a chlorhexidine decontamination-MOD9 solid medium protocol versus the standard NALC-NaOH-Bactec 960 MGIT protocol for the diagnosis of pulmonary tuberculosis by culture. Three-hundred clinical specimens comprising 193 sputa, 30 bronchial aspirates, 10 broncho-alveolar lavages, 47 stools, and 20 urines were prospectively submitted for the routine diagnosis of tuberculosis. The contamination rates were 5/300 (1.7%) using the MOD9 protocol and 17/300 (5.7%) with the Bactec protocol, respectively (P < 0.05, Fisher exact test). Of a total of 50 Mycobacterium isolates (48 M. tuberculosis and two Mycobacterium abscessus) were cultured. Out of these 50, 48 (96%) isolates were found using the MOD9 protocol versus 35 (70%) when using the Bactec protocol (P < 0.05, Fisher exact test). The time to positivity was 10.1 ± 3.9 days versus 14.7 ± 7.3 days, respectively, (P < 0.05, Student's t-test). These data confirmed the usefulness of parallel inoculation of a solid culture medium with broth for the recovery of M. tuberculosis in agreement with current recommendations. More specifically, chlorhexidine decontamination and inoculation of the MOD9 solid medium could be proposed to complement the standard Bactec 960 MGIT broth protocol. PMID:26834733

  13. Biosynthesis of Gold Nanoparticles by Foliar Broths: Roles of Biocompounds and Other Attributes of the Extracts

    NASA Astrophysics Data System (ADS)

    Zhou, Yao; Lin, Wenshuang; Huang, Jiale; Wang, Wenta; Gao, Yixian; Lin, Liqin; Li, Qingbiao; Lin, Ling; Du, Mingming

    2010-08-01

    Biosynthesis of nanoparticles has arisen as a promising alternative to conventional synthetic methodologies owing to its eco-friendly advantages, and the involved bioprotocol still needs further clarification. This research, for the first time from the standpoint of statistics, confirmed an electrostatic force or ionic bond-based interaction between the chloroauric ions and the involved bioconstituents and manifested that reducing sugars and flavonoids were both important reductants responsible for conversion of Au(III) to Au(0). The result also demonstrated that the proteins were not the reducing agents, yet they might be protection agents in biosynthesis of gold nanoparticles (GNPs). Besides, a significant linear relationship was found between the anti-oxidant ability of the foliar broths and their capability to reduce Au(III) into Au(0). Furthermore, the preliminary investigation based on the boxplot on the size/shape distribution of the biosynthesized GNPs revealed that gold nanospheres with higher degree of homogeneity in size tended to be promoted by foliar broths containing higher content of reducing sugars/flavonoids and proteins. Otherwise, i.e., for those broths with lower content of the above biocompounds, sphere GNPs of wider size distribution or even gold nanotriangles tended to be fabricated.

  14. Development and Validation of a Rapid 13C6-Glucose Isotope Dilution UPLC-MRM Mass Spectrometry Method for Use in Determining System Accuracy and Performance of Blood Glucose Monitoring Devices

    PubMed Central

    Matsunami, Risë K.; Angelides, Kimon; Engler, David A.

    2015-01-01

    Background: There is currently considerable discussion about the accuracy of blood glucose concentrations determined by personal blood glucose monitoring systems (BGMS). To date, the FDA has allowed new BGMS to demonstrate accuracy in reference to other glucose measurement systems that use the same or similar enzymatic-based methods to determine glucose concentration. These types of reference measurement procedures are only comparative in nature and are subject to the same potential sources of error in measurement and system perturbations as the device under evaluation. It would be ideal to have a completely orthogonal primary method that could serve as a true standard reference measurement procedure for establishing the accuracy of new BGMS. Methods: An isotope-dilution liquid chromatography/mass spectrometry (ID-UPLC-MRM) assay was developed using 13C6-glucose as a stable isotope analogue to specifically measure glucose concentration in human plasma, and validated for use against NIST standard reference materials, and against fresh isolates of whole blood and plasma into which exogenous glucose had been spiked. Assay performance was quantified to NIST-traceable dry weight measures for both glucose and 13C6-glucose. Results: The newly developed assay method was shown to be rapid, highly specific, sensitive, accurate, and precise for measuring plasma glucose levels. The assay displayed sufficient dynamic range and linearity to measure across the range of both normal and diabetic blood glucose levels. Assay performance was measured to within the same uncertainty levels (<1%) as the NIST definitive method for glucose measurement in human serum. Conclusions: The newly developed ID UPLC-MRM assay can serve as a validated reference measurement procedure to which new BGMS can be assessed for glucose measurement performance. PMID:25986627

  15. Multicenter evaluation of a broth macrodilution antifungal susceptibility test for yeasts.

    PubMed Central

    Fromtling, R A; Galgiani, J N; Pfaller, M A; Espinel-Ingroff, A; Bartizal, K F; Bartlett, M S; Body, B A; Frey, C; Hall, G; Roberts, G D

    1993-01-01

    Thirteen laboratories collaborated to optimize interlaboratory agreement of results of a broth macrodilution procedure for testing three classes of antifungal drugs against pathogenic yeasts. The activities of amphotericin B, flucytosine, and ketoconazole were tested against 100 coded isolates of Candida albicans, Candida tropicalis, Candida parapsilosis, Candida lusitaniae, Torulopsis (Candida) glabrata, and Cryptococcus neoformans. Two starting yeast inoculum sizes (5 x 10(4) and 2.5 x 10(3) cells per ml) were compared, and readings were taken after 24 and 48 h of incubation. All other test conditions were standardized. The resultant turbidities in all tubes were estimated visually on a scale from 0 to 4+ turbidity, and MIC-0, MIC-1, and MIC-2 were defined as the lowest drug concentrations that reduced growth to 0, 1+, or 2+ turbidity, respectively. For flucytosine, agreement among laboratories varied between 57 and 87% for different inocula, times of incubation, and end point criteria. Agreement was maximized (85%) when the lower inoculum was incubated for 2 days and the MICs were defined as 1+ turbidity or less. For amphotericin B, variations in test conditions produced much smaller differences in interlaboratory agreement. For ketoconazole, interlaboratory agreement was poorer by all end point criteria. However, MIC-2 endpoints distinguished T. glabrata as resistant compared with the other species. Overall, the studies indicated that readings from the lower inoculum obtained on the second day of reading result in the greatest interlaboratory agreement. In combination with data from previous multicenter studies (National Committee for Clinical Laboratory Standards, Antifungal Susceptibility Testing: Committee Report, Vol. 5, No. 17, 1988; M. A. Pfaller, L. Burmeister, M. S. Bartlett, and M. G. Rinaldi, J. Clin. Microbiol. 26:1437-1441, 1988; M. A. Pfaller, M. G. Rinaldi, J. N. Galgiani, M. S. Bartlett, B.A. Body, A. Espinel-Ingroff, R.A. Fromtling, G.S. Hall, C

  16. A cryopreservation method for Pasteurella multocida from wetland samples

    USGS Publications Warehouse

    Moore, Melody K.; Shadduck, D.J.; Goldberg, D.R.; Samuel, M.D.

    1998-01-01

    A cryopreservation method and improved isolation techniques for detection of Pasteurella multocida from wetland samples were developed. Wetland water samples were collected in the field, diluted in dimethyl sulfoxide (DMSO, final concentration 10%), and frozen at -180 C in a liquid nitrogen vapor shipper. Frozen samples were transported to the laboratory where they were subsequently thawed and processed in Pasteurella multocida selective broth (PMSB) to isolate P. multocida. This method allowed for consistent isolation of 2 to 18 organisms/ml from water seeded with known concentrations of P. multocida. The method compared favorably with the standard mouse inoculation method and allowed for preservation of the samples until they could be processed in the laboratory.

  17. A cryopreservation method for Pasteurella multocida from wetland samples.

    PubMed

    Moore, M K; Shadduck, D J; Goldberg, D R; Samuel, M D

    1998-01-01

    A cryopreservation method and improved isolation techniques for detection of Pasteurella multocida from wetland samples were developed. Wetland water samples were collected in the field, diluted in dimethyl sulfoxide (DMSO, final concentration 10%), and frozen at -180 C in a liquid nitrogen vapor shipper. Frozen samples were transported to the laboratory where they were subsequently thawed and processed in Pasteurella multocida selective broth (PMSB) to isolate P. multocida. This method allowed for consistent isolation of 2 to 18 organisms/ml from water seeded with known concentrations of P. multocida. The method compared favorably with the standard mouse inoculation method and allowed for preservation of the samples until they could be processed in the laboratory. PMID:9476245

  18. Science Notes: Dilution of a Weak Acid

    ERIC Educational Resources Information Center

    Talbot, Christopher; Wai, Chooi Khee

    2014-01-01

    This "Science note" arose out of practical work involving the dilution of ethanoic acid, the measurement of the pH of the diluted solutions and calculation of the acid dissociation constant, K[subscript a], for each diluted solution. The students expected the calculated values of K[subscript a] to be constant but they found that the…

  19. Automated harvesting and 2-step purification of unclarified mammalian cell-culture broths containing antibodies.

    PubMed

    Holenstein, Fabian; Eriksson, Christer; Erlandsson, Ioana; Norrman, Nils; Simon, Jill; Danielsson, Åke; Milicov, Adriana; Schindler, Patrick; Schlaeppi, Jean-Marc

    2015-10-30

    Therapeutic monoclonal antibodies represent one of the fastest growing segments in the pharmaceutical market. The growth of the segment has necessitated development of new efficient and cost saving platforms for the preparation and analysis of early candidates for faster and better antibody selection and characterization. We report on a new integrated platform for automated harvesting of whole unclarified cell-culture broths, followed by in-line tandem affinity-capture, pH neutralization and size-exclusion chromatography of recombinant antibodies expressed transiently in mammalian human embryonic kidney 293T-cells at the 1-L scale. The system consists of two bench-top chromatography instruments connected to a central unit with eight disposable filtration devices used for loading and filtering the cell cultures. The staggered parallel multi-step configuration of the system allows unattended processing of eight samples in less than 24h. The system was validated with a random panel of 45 whole-cell culture broths containing recombinant antibodies in the early profiling phase. The results showed that the overall performances of the preparative automated system were higher compared to the conventional downstream process including manual harvesting and purification. The mean recovery of purified material from the culture-broth was 66.7%, representing a 20% increase compared to that of the manual process. Moreover, the automated process reduced by 3-fold the amount of residual aggregates in the purified antibody fractions, indicating that the automated system allows the cost-efficient and timely preparation of antibodies in the 20-200mg range, and covers the requirements for early in vitro and in vivo profiling and formulation of these drug candidates. PMID:26431859

  20. Method to simultaneously determine the sphingosine 1-phosphate breakdown product (2E)-hexadecenal and its fatty acid derivatives using isotope-dilution HPLC-electrospray ionization-quadrupole/time-of-flight mass spectrometry.

    PubMed

    Neuber, Corinna; Schumacher, Fabian; Gulbins, Erich; Kleuser, Burkhard

    2014-09-16

    Sphingosine 1-phosphate (S1P), a bioactive lipid involved in various physiological processes, can be irreversibly degraded by the membrane-bound S1P lyase (S1PL) yielding (2E)-hexadecenal and phosphoethanolamine. It is discussed that (2E)-hexadecenal is further oxidized to (2E)-hexadecenoic acid by the long-chain fatty aldehyde dehydrogenase ALDH3A2 (also known as FALDH) prior to activation via coupling to coenzyme A (CoA). Inhibition or defects in these enzymes, S1PL or FALDH, result in severe immunological disorders or the Sjögren-Larsson syndrome, respectively. Hence, it is of enormous importance to simultaneously determine the S1P breakdown product (2E)-hexadecenal and its fatty acid metabolites in biological samples. However, no method is available so far. Here, we present a sensitive and selective isotope-dilution high performance liquid chromatography-electrospray ionization-quadrupole/time-of-flight mass spectrometry method for simultaneous quantification of (2E)-hexadecenal and its fatty acid metabolites following derivatization with 2-diphenylacetyl-1,3-indandione-1-hydrazone and 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide. Optimized conditions for sample derivatization, chromatographic separation, and MS/MS detection are presented as well as an extensive method validation. Finally, our method was successfully applied to biological samples. We found that (2E)-hexadecenal is almost quantitatively oxidized to (2E)-hexadecenoic acid, that is further activated as verified by cotreatment of HepG2 cell lysates with (2E)-hexadecenal and the acyl-CoA synthetase inhibitor triacsin C. Moreover, incubations of cell lysates with deuterated (2E)-hexadecenal revealed that no hexadecanoic acid is formed from the aldehyde. Thus, our method provides new insights into the sphingolipid metabolism and will be useful to investigate diseases known for abnormalities in long-chain fatty acid metabolism, e.g., the Sjögren-Larsson syndrome, in more detail. PMID:25137547

  1. Efficient ethanol recovery from fermentation broths with integrated distillation-membrane process

    EPA Science Inventory

    The energy demand of distillation-molecular sieve systems for ethanol recovery/dehydration can be significant, particularly for dilute solutions. An alternative process integrating vapor stripping (like a beer still) with vapor compression and a vapor permeation membrane separati...

  2. Shock Compression and Recovery of Microorganism-Loaded Broths and AN Emulsion

    NASA Astrophysics Data System (ADS)

    Hazell, P. J.; Beveridge, C.; Groves, K.; Stennett, C.

    2009-12-01

    The microorganisms Escherichia coli, Enterococcus faecalis and Zygosaccharomyces bailii and an oil-based emulsion, have been subjected to shock compression using the flyer-plate technique to initial pressures of 0.8 GPa (in the suspension). In each experiment, a stainless steel capsule was used to contain the broths and allow for recovery without contamination. Where cavitation was mostly suppressed by virtue of simultaneous shock and dynamic compression, no kill was observed. By introducing an air gap behind the suspension, limited kill was measured in the yeast. Results also suggest that stable emulsification occurs in coarse oil-based emulsions that are subjected to shock.

  3. Erinaceolactones A to C, from the culture broth of Hericium erinaceus.

    PubMed

    Wu, Jing; Tokunaga, Taiki; Kondo, Mitsuru; Ishigami, Kota; Tokuyama, Shinji; Suzuki, Tomohiro; Choi, Jae-Hoon; Hirai, Hirofumi; Kawagishi, Hirokazu

    2015-01-23

    Three novel compounds, erinaceolactones A to C (1-3), and a known compound (4) were isolated from the culture broth of Hericium erinaceus. The planar structures of 1-3 were determined by the interpretation of spectroscopic data. The absolute configuration of 3 was determined by X-ray crystallography. Although compound 4 had been synthesized, it was isolated from a natural source for the first time. In the bioassay examining plant-growth regulatory activity of these compounds (1-4) and other components of the fungus (5-8), compounds 1, 2, and 4-8 suppressed the growth of lettuce. PMID:25534373

  4. Isotope dilution study of exchangeable oxygen in premium coal samples

    SciTech Connect

    Finseth, D.

    1987-01-01

    A difficulty with improving the ability to quantitate water in coal is that truly independent methods do not always exist. The true value of any analytical parameter is always easier to determine if totally independent methods exist to determine that parameter. This paper describes the possibility of using a simple isotope dilution technique to determine the water content of coal and presents a comparison of these isotope dilution measurements with classical results for the set of Argonne coals from the premium coal sample program. Isotope dilution is a widely used analytical method and has been applied to the analysis of water in matrices as diverse as chicken fat, living humans, and coal. Virtually all of these applications involved the use of deuterium as the diluted isotope. This poses some problems if the sample contains a significant amount of exchangeable organic hydrogen and one is interested in discriminating exchangeable organic hydrogen from water. This is a potential problem in the coal system. To avoid this potential problem /sup 18/O was used as the diluted isotope in this work.

  5. Fate of Alicyclobacillus spp. in enrichment broth and in juice concentrates.

    PubMed

    Oteiza, Juan Martin; Soto, Silvina; Alvarenga, Verônica O; Sant'Ana, Anderson S; Gianuzzi, Leda

    2015-10-01

    In this study, the fate of Alicyclobacillus acidoterrestris spores in different types of juice concentrates stored under different conditions was investigated. In addition, the impact of dilution procedures during the enrichment step for the detection of Alicyclobacillus in lemon juice concentrates was studied. Pear, red grape, mango, tangerine, carrot and lemon juice concentrates (50-69.4°Brix, pH1.7-4.3) were inoculated with A. acidoterrestris spores (10(3) spore/mL) and stored at 4 °C and 20 °C, after which the spores were counted at 0, 2, 5, 9, 17, 21, 28, 36, 43, and 50 days. No significant differences in the number of Alicyclobacillus spores were observed at storage temperatures of 4 °C and 20 °C (p>0.05). The results also indicated that the number of spores of A. acidoterrestris remained stable in all types of juice concentrates during the storage period, except in lemon juice concentrate. In lemon juice concentrate, a decline in A. acidoterrestris spore populations of 0.3-0.8 log CFU/mL was observed within 5-10 days of storage. The decline in A. acidoterrestris spore populations was more pronounced in cloudy lemon juice concentrate, which contained higher concentrations of flavonoids (mainly eriocitrin and hesperidin) than clarified lemon juice concentrate. It was also found that dilution of lemon juice concentrate samples in the proportion of 1:19 allowed the germination of A. acidoterrestris spores and the growth of populations of up to 10(7) CFU/mL. In contrast, the proportion (1:9) recommended in internationally recognized methods led to a reduction in the population of this microorganism that would yield false negative results. Data presented in this study demonstrated that Alicyclobacillus spores remain stable in most juice concentrates during storage, but that natural antimicrobial compounds present in some of them may decrease spore counts and inhibit their recovery by detection procedures. PMID:26102554

  6. Detection of Burkholderia pseudomallei in Sputum using Selective Enrichment Broth and Ashdown's Medium at Kampong Cham Provincial Hospital, Cambodia.

    PubMed

    Nhem, Somary; Letchford, Joanne; Meas, Chea; Thann, Sovanndeth; McLaughlin, James C; Baron, Ellen Jo; West, T Eoin

    2014-01-01

    Melioidosis, infection caused by Burkholderia pseudomallei, is increasingly reported in Cambodia. We hypothesized that implementation of an enhanced sputum testing protocol in a provincial hospital diagnostic microbiology laboratory would increase detection of B. pseudomallei. We tested 241 sputum specimens that were deemed acceptable for culture, comparing culture in selective enrichment broth followed by sub-culture on Ashdown's medium to standard culture methods. Two specimens (0.8%) were positive for B. pseudomallei using the enhanced protocol whereas one specimen (0.4%) was positive using standard methods. Given the low numbers of positive specimens, we could not conclusively determine the utility of the enhanced sputum testing protocol. However, the ramifications of identification of  B. pseudomallei are substantial, and the benefit of the enhanced testing protocol may be more apparent in patients selected based on risk factors and clinical presentation. Promoting clinician awareness of the infection and encouraging utilization of diagnostic microbiology services are also likely to be important factors in facilitating identification of melioidosis. PMID:25717370

  7. Development of a repair-enrichment broth for resuscitation of heat-injured Listeria monocytogenes and Listeria innocua.

    PubMed Central

    Busch, S V; Donnelly, C W

    1992-01-01

    The ability of the divalent cations magnesium, iron, calcium and manganese; yeast extract; pyruvate; catalase; and the carbohydrates glucose, lactose, sucrose, esculin, fructose, galactose, maltose, and mannose to facilitate repair of heat-injured Listeria monocytogenes and Listeria innocua was evaluated. Listeria populations were injured by heating at 56 degrees C for 50 min. To determine the effects on repair, Trypticase soy broth (TSB) was supplemented with each medium component to be evaluated. Repair occurred to various degrees within 5 h in TSB supplemented with glucose, lactose, sucrose, yeast extract, pyruvate, or catalase. Chelex-exchanged TSB was supplemented with divalent cations; magnesium and iron cations were found to have a role in repair. Listeria repair broth (LRB) was formulated by utilizing the components that had the greatest impact upon repair. When incubated in LRB, heat-injured Listeria cells completed repair in 5 h. After the repair, acriflavin, nalidixic acid, and cycloheximide were added to LRB to yield final concentrations identical to those of the selective enrichment broths used in the procedures of the Food and Drug Administration and the U.S. Department of Agriculture. The efficacy of LRB in promoting repair and enrichment of heat-injured Listeria cells was compared with that of existing selective enrichment broths. Repair was not observed in the Food and Drug Administration enrichment broth, Listeria enrichment broth, or University of Vermont enrichment broth. The final Listeria populations after 24 h of incubation in selective enrichment media were 1.7 x 10(8) to 9.1 x 10(8) CFU/ml; populations in LRB consistently averaged 2.5 x 10(11) to 8.2 x 10(11) CFU/ml. PMID:1531746

  8. Crude oil biodegradation aided by biosurfactants from Pseudozyma sp. NII 08165 or its culture broth.

    PubMed

    Sajna, Kuttuvan Valappil; Sukumaran, Rajeev Kumar; Gottumukkala, Lalitha Devi; Pandey, Ashok

    2015-09-01

    The aim of this work was to evaluate the biosurfactants produced by the yeast Pseudozyma sp. NII 08165 for enhancing the degradation of crude oil by a model hydrocarbon degrading strain, Pseudomonas putida MTCC 1194. Pseudozyma biosurfactants were supplemented at various concentrations to the P. putida culture medium containing crude oil as sole carbon source. Supplementation of the biosurfactants enhanced the degradation of crude oil by P. putida; the maximum degradation of hydrocarbons was observed with a 2.5 mg L(-1) supplementation of biosurfactants. Growth inhibition constant of the Pseudozyma biosurfactants was 11.07 mg L(-1). It was interesting to note that Pseudozyma sp. NII 08165 alone could also degrade diesel and kerosene. Culture broth of Pseudozyma containing biosurfactants resulted up to ∼46% improvement in degradation of C10-C24 alkanes by P. putida. The enhancement in degradation efficiency of the bacterium with the culture broth supplementation was even more pronounced than that with relatively purer biosurfactants. PMID:25985416

  9. 2,3-Butanediol recovery from fermentation broth by alcohol precipitation and vacuum distillation.

    PubMed

    Jeon, Sangjun; Kim, Duk-Ki; Song, Hyohak; Lee, Hee Jong; Park, Sunghoon; Seung, Doyoung; Chang, Yong Keun

    2014-04-01

    This study presents a new and effective downstream process to recover 2,3-butanediol (2,3-BD) from fermentation broth which is produced by a recombinant Klebsiella pneumoniae strain. The ldhA-deficient K. pneumoniae strain yielded about 90 g/L of 2,3-BD, along with a number of by-products, such as organic acids and alcohols, in a 65 h fed-batch fermentation. The pH-adjusted cell-free fermentation broth was firstly concentrated until 2,3-BD reached around 500 g/L by vacuum evaporation at 50°C and 50 mbar vacuum pressure. The concentrated solution was further treated using light alcohols, including methanol, ethanol, and isopropanol, for the precipitation of organic acids and inorganic salts. Isopropanol showed the highest removal efficiency, in which 92.5% and 99.8% of organic acids and inorganic salts were precipitated, respectively. At a final step, a vacuum distillation process enabled the recovery of 76.2% of the treated 2,3-BD, with 96.1% purity, indicating that fermentatively produced 2,3-BD is effectively recovered by a simple alcohol precipitation and vacuum distillation. PMID:24144809

  10. Antibacterial activity of 11 essential oils against Bacillus cereus in tyndallized carrot broth.

    PubMed

    Valero, M; Salmerón, M C

    2003-08-15

    The antibacterial activity of 11 essential oils from aromatic plants against the strain INRA L2104 of the foodborne pathogen Bacillus cereus grown in carrot broth at 16 degrees C was studied. The quantity needed by the essential oils of nutmeg, mint, clove, oregano, cinnamon, sassafras, sage, thyme or rosemary to produce 14-1110% relative extension of the lag phase was determined. Total growth inhibition of bacterial spores was observed for some of the antimicrobial agents assayed. The addition of 5 microl cinnamon essential oil per 100 ml of broth in combination with refrigeration temperatures of

  11. High pressure inactivation of Pseudomonas in black truffle - comparison with Pseudomonas fluorescens in tryptone soya broth

    NASA Astrophysics Data System (ADS)

    Ballestra, Patricia; Verret, Catherine; Cruz, Christian; Largeteau, Alain; Demazeau, Gerard; El Moueffak, Abdelhamid

    2010-03-01

    Pseudomonas is one of the most common genera in black Perigord truffle. Its inactivation by high pressure (100-500 MPa/10 min) applied on truffles at sub-zero or low temperatures was studied and compared with those of Pseudomonas fluorescens in tryptone soya broth. Pressurization of truffles at 300 MPa/4 °C reduced the bacterial count of Pseudomonas by 5.3 log cycles. Higher pressures of 400 or 500 MPa, at 4 °C or 20 °C, allowed us to slightly increase the level of destruction to the value of ca. 6.5 log cycles but did not permit us to completely inactivate Pseudomonas. The results showed a residual charge of about 10 CFU/g. Pressure-shift freezing of truffles, which consists in applying a pressure of 200 MPa/-18 °C for 10 min and then quickly releasing this pressure to induce freezing, reduced the population of Pseudomonas by 3.3 log cycles. The level of inactivation was higher than those obtained with conventional freezing. Endogenous Pseudomonas in truffle was shown to be more resistant to high pressure treatments than P. fluorescens used for inoculation of broths.

  12. Fermentation broth components influence droplet coalescence and hinder advanced biofuel recovery during fermentation.

    PubMed

    Heeres, Arjan S; Schroën, Karin; Heijnen, Joseph J; van der Wielen, Luuk A M; Cuellar, Maria C

    2015-08-01

    Developments in synthetic biology enabled the microbial production of long chain hydrocarbons, which can be used as advanced biofuels in aviation or transportation. Currently, these fuels are not economically competitive due to their production costs. The current process offers room for improvement: by utilizing lignocellulosic feedstock, increasing microbial yields, and using cheaper process technology. Gravity separation is an example of the latter, for which droplet growth by coalescence is crucial. The aim of this study was to study the effect of fermentation broth components on droplet coalescence. Droplet coalescence was measured using two setups: a microfluidic chip and regular laboratory scale stirred vessel (2 L). Some fermentation broth components had a large impact on droplet coalescence. Especially components present in hydrolysed cellulosic biomass and mannoproteins from the yeast cell wall retard coalescence. To achieve a technically feasible gravity separation that can be integrated with the fermentation, the negative effects of these components on coalescence should be minimized. This could be achieved by redesign of the fermentation medium or adjusting the fermentation conditions, aiming to minimize the release of surface active components by the microorganisms. This way, another step can be made towards economically feasible advanced biofuel production. PMID:26097113

  13. Preparation of maltotriose from fermentation broth by hydrolysis of pullulan using pullulanase.

    PubMed

    Wu, Sheng-Jun; Chen, Jing

    2014-07-17

    In this study, we prepared maltotriose from the fermentation broth of Auerobasidium Pullulans CJ001 isolated from the sea mud by hydrolysis of pullulan with pullulanase. The fermentation broth was centrifuged to remove the microorganisms and then hydrolysed by pullulanase. The optimal hydrolysis conditions were obtained as follows: time, 9.40 h; pH, 4.92; temperature, 47.88°C; pullulanase, 10ASPU/g. Under these optimum hydrolysis conditions, the maximum dextrose equivalent value reached 31.86. The hydrolysates were filtrated through a filter membrane to separate any particle with molecular weight higher than 1,000 Da, concentrated to ∼20%, and precipitated with 8 volumes of absolute ethanol. The precipitate was dried at 80°C for 2h to yield the maltotriose product. The maltotriose content in the product and the yield of maltotriose were 92.13% and 90.23%, respectively. The results indicate that this was a promising way of maltotriose production. PMID:24702922

  14. Dilute acid and autohydrolysis pretreatment.

    PubMed

    Yang, Bin; Wyman, Charles E

    2009-01-01

    Exposure of cellulosic biomass to temperatures of about 120-210 degrees C can remove most of the hemicellulose and produce cellulose-rich solids from which high glucose yields are possible with cellulase enzymes. Furthermore, the use of dilute sulfuric acid in this pretreatment operation can increase recovery of hemicellulose sugars substantially to about 85-95% of the maximum possible versus only about 65% if no acid is employed. The use of small-diameter tubes makes it possible to employ high solids concentrations similar to those preferred for commercial operations, with rapid heat-up, good temperature control, and accurate closure of material balances. Mixed reactors can be employed to pretreat larger amounts of biomass than possible in such small-diameter tubes, but solids concentrations are limited to about 15% or less to provide uniform temperatures. Pretreatment of large amounts of biomass at high solids concentrations is best carried out using direct steam injection and rapid pressure release, but closure of material balances in such "steam gun" devices is more difficult. Although flow of water alone or containing dilute acid is not practical commercially, such flow-through configurations provide valuable insight into biomass deconstruction kinetics not possible in the batch tubes, mixed reactors, or steam gun systems. PMID:19768619

  15. A Microgravity Helium Dilution Cooler

    NASA Technical Reports Server (NTRS)

    Roach, Pat R.; Sperans, Joel (Technical Monitor)

    1994-01-01

    We are developing a He-3-He-4 dilution cooler to operate in microgravity. It uses charcoal adsorption pumps and heaters for its operation; it has no moving parts. It currently operates cyclically to well below 0.1 K and we have designed a version to operate continuously. We expect that the continuous version will be able to provide the long-duration cooling that many experiments need at temperatures down to 0.040 K. More importantly, such a dilution cooler could provide the precooling that enables the use of adiabatic demagnetization techniques that can reach temperatures below 0.001 K. At temperatures below 0.002 K many fascinating microgravity experiments on superfluid He-3 become possible. Among the possibilities are: research into a superfluid He-3 gyroscope, study of the nucleation of the B-phase of superfluid He-3 when the sample is floating out of contact with walls, study of the anisotropy of the surface tension of the B-phase, and NMR experiments on tiny free-floating clusters of superfluid He-3 atoms that should model the shell structure of nuclei.

  16. Dilute Potts model in two dimensions.

    PubMed

    Qian, Xiaofeng; Deng, Youjin; Blöte, Henk W J

    2005-11-01

    We study the two-dimensional dilute q-state Potts model by means of transfer-matrix and Monte Carlo methods. Using the random-cluster representation, we include noninteger values of q. We locate phase transitions in the three-dimensional parameter space of q, the Potts coupling K>0, and the chemical potential of the vacancies. The critical plane is found to contain a line of fixed points that divides into a critical branch and a tricritical one, just as predicted by the renormalization scenario formulated by Nienhuis et al for the dilute Potts model. The universal properties along the line of fixed points agree with the theoretical predictions. We also determine the density of the vacancies along these branches. For q=2-squareroot of 2 we obtain the phase diagram in a three-dimensional parameter space that also includes a coupling V> or = 0 between the vacancies. For q=2, the latter space contains the Blume-Capel model as a special case. We include a determination of the tricritical point of this model, as well as an analysis of percolation clusters constructed on tricritical Potts configurations for noninteger q. This percolation study is based on Monte Carlo algorithms that include local updates flipping between Potts sites and vacancies. The bond updates are performed locally for and by means of a cluster algorithm for q>1. The updates for q>1 use a number of operations per site independent of the system size. PMID:16383713

  17. Dilute Potts model in two dimensions

    NASA Astrophysics Data System (ADS)

    Qian, Xiaofeng; Deng, Youjin; Blöte, Henk W. J.

    2005-11-01

    We study the two-dimensional dilute q -state Potts model by means of transfer-matrix and Monte Carlo methods. Using the random-cluster representation, we include noninteger values of q . We locate phase transitions in the three-dimensional parameter space of q , the Potts coupling K⩾0 , and the chemical potential of the vacancies. The critical plane is found to contain a line of fixed points that divides into a critical branch and a tricritical one, just as predicted by the renormalization scenario formulated by Nienhuis for the dilute Potts model. The universal properties along the line of fixed points agree with the theoretical predictions. We also determine the density of the vacancies along these branches. For q=2-2 we obtain the phase diagram in a three-dimensional parameter space that also includes a coupling V⩾0 between the vacancies. For q=2 , the latter space contains the Blume-Capel model as a special case. We include a determination of the tricritical point of this model, as well as an analysis of percolation clusters constructed on tricritical Potts configurations for noninteger q . This percolation study is based on Monte Carlo algorithms that include local updates flipping between Potts sites and vacancies. The bond updates are performed locally for q<1 and by means of a cluster algorithm for q>1 . The updates for q>1 use a number of operations per site independent of the system size.

  18. A convenient method for differentiation of coagulase-negative staphylococci isolated from bovine mammary glands.

    PubMed

    Watts, J L; Ray, C H; Washburn, P J

    1991-02-01

    The utility of trehalose-mannitol broth and arabinose-cellobiose broth for identification of Staphylococcus epidermidis and novobiocin-resistant staphylococci was determined using 236 coagulase-negative staphylococci isolated from bovine mammary glands. None of the 49 S. epidermidis strains was positive in trehalose-mannitol broth; whereas, all strains of Staphylococcus hyicus, Staphylococcus chromogenes, Staphylococcus haemolyticus, Staphylococcus hominis, Staphylococcus warneri, and Staphylococcus simulans were positive. Of the novobiocin-resistant staphylococcal species, only Staphylococcus saprophyticus was negative in arabinose-cellobiose broth. Except for one strain of Staphylococcus sciuri and one strain of Staphylococcus kloosii, all remaining strains of novobiocin-resistant staphylococcal species were positive in arabinose-cellobiose broth. Results indicate that trehalose-mannitol broth is an acceptable method for identification of S. epidermidis isolated from bovine mammary glands. Furthermore, arabinose-cellobiose broth is a useful method of screening for novobiocin-resistant staphylococci. PMID:2045549

  19. Maximum independent set on diluted triangular lattices.

    PubMed

    Fay, C W; Liu, J W; Duxbury, P M

    2006-05-01

    Core percolation and maximum independent set on random graphs have recently been characterized using the methods of statistical physics. Here we present a statistical physics study of these problems on bond diluted triangular lattices. Core percolation critical behavior is found to be consistent with the standard percolation values, though there are strong finite size effects. A transfer matrix method is developed and applied to find accurate values of the density and degeneracy of the maximum independent set on lattices of limited width but large length. An extrapolation of these results to the infinite lattice limit yields high precision results, which are tabulated. These results are compared to results found using both vertex based and edge based local probability recursion algorithms, which have proven useful in the analysis of hard computational problems, such as the satisfiability problem. PMID:16803003

  20. Determination of direct photolysis rate constants and OH radical reactivity of representative odour compounds in brewery broth using a continuous flow-stirred photoreactor

    NASA Astrophysics Data System (ADS)

    Jürgens, Marion; Jacob, Fritz; Ekici, Perihan; Friess, Albrecht; Parlar, Harun

    A method based on photolysis was developed for the appropriate treatment of organic pollutants in air exhausting from breweries upon wort decoction, and thereby causing smell nuisance. A continuous flow stirred photoreactor was built-up exclusively, allowing OH radicals to react with selected odorous compounds contained in exhaust vapours, such as: 2-methylpropanal, 3-methylbutanal, 2-methylbutanal, 3-methyl-1-butanol, n-hexanal, 2-methylbutyl isobutyrate, 2-undecanone, phenyl acetaldehyde, myrcene, limonene, linalool, humulene, dimethylsulphide, and dimethyltrisulphide. These substances were quantified in brewery broth before and after UV irradiation using high-resolution gas chromatography-mass spectrometry (HRGC-MS). For odour analysis, high-resolution gas chromatography-flame ionisation detection (HRGC-FID) coupled with sensory methods was used. Determined quantum yields of about 10 -3 for phenyl acetaldehyde, myrcene, and humulene pointed out that direct photolysis contributed to their decay. Quantum yields of below 10 -4 for the other substances indicated that UV irradiation did not contribute significantly to their degradation processes. Hydroxyl radical reaction rate constants and Henry constants of organic compounds were also measured. Substances accompanied with low Henry constants converted rapidly, whereas those with higher ones, relatively slowly. Determined aroma values concluded that after UV-H 2O 2 treatment, only dimethylsulphide and myrcene remained as important odorous compounds, but in significantly reduced concentrations. The UV-H 2O 2 treatment of brewery broth has been proved effective to reduce smell-irritating substances formed upon wort decoction.

  1. Total body water and lean body mass estimated by ethanol dilution

    NASA Technical Reports Server (NTRS)

    Loeppky, J. A.; Myhre, L. G.; Venters, M. D.; Luft, U. C.

    1977-01-01

    A method for estimating total body water (TBW) using breath analyses of blood ethanol content is described. Regression analysis of ethanol concentration curves permits determination of a theoretical concentration that would have existed if complete equilibration had taken place immediately upon ingestion of the ethanol; the water fraction of normal blood may then be used to calculate TBW. The ethanol dilution method is applied to 35 subjects, and comparison with a tritium dilution method of determining TBW indicates that the correlation between the two procedures is highly significant. Lean body mass and fat fraction were determined by hydrostatic weighing, and these data also prove compatible with results obtained from the ethanol dilution method. In contrast to the radioactive tritium dilution method, the ethanol dilution method can be repeated daily with its applicability ranging from diseased individuals to individuals subjected to thermal stress, strenuous exercise, water immersion, or the weightless conditions of space flights.

  2. Are E-test and Vitek2 good choices for tigecycline susceptibility testing when comparing broth microdilution for MDR and XDR Acinetobacter baumannii?

    PubMed

    Grandesso, Stefano; Sapino, Barbara; Amici, Gianpaolo; Mazzucato, Sandra; Solinas, Maria; Gion, Massimo

    2014-10-01

    This study reports the results of antimicrobial susceptibility testing of 10 MDR and 74 XDR Acinetobacter bauman- nii clinical isolates from our hospital routine. We used three different methods: two automated systems (Sensititre and VITEK 2) and one standardized manual method (E-test). Since many published papers refer to in vitro tests performed by E-test, the aim of this study was to test if this method is reliable for testing tigecycline. The results obtained show that E-test significantly overestimates the MIC of the broth microdilution (reference test), thus ob- taining a significant number of major errors (resistant instead of sensitive). VITEK 2 also shows the same problem, but it is less critical. We therefore conclude that these methods do not seem to be very reliable in the performance of susceptibility testing of MDR and XDR Acinetobacter baumannii against tigecycline. PMID:25387287

  3. Residual Resistivity of Dilute Alloys

    NASA Astrophysics Data System (ADS)

    Vora, Aditya M.

    The residual resistivity for 156 dilute alloys of 19 hosts of different groups of the periodic table has been studied on the basis of the single parametric model potential formalism. Ashcroft's empty core model (EMC) potential is explored for the first time with five different local field correction functions, viz, Hartree (H), Taylor (T), Ichimaru-Utsumi (IU), Farid et al. (F), and Sarkar et al. (S) to investigate the effect of the exchange and correlation on the aforesaid properties. The comparison of the presently computed outcomes with the available theoretical and experimental data is highly encouraging. The investigation of residual resistivity is found to be quite sensitive to the selection of local field correction function, showing a significant variation with the change in the function.

  4. Band anticrossing in dilute nitrides

    SciTech Connect

    Shan, W.; Yu, K.M.; Walukiewicz, W.; Wu, J.; Ager III, J.W.; Haller, E.E.

    2003-12-23

    Alloying III-V compounds with small amounts of nitrogen leads to dramatic reduction of the fundamental band-gap energy in the resulting dilute nitride alloys. The effect originates from an anti-crossing interaction between the extended conduction-band states and localized N states. The interaction splits the conduction band into two nonparabolic subbands. The downward shift of the lower conduction subband edge is responsible for the N-induced reduction of the fundamental band-gap energy. The changes in the conduction band structure result in significant increase in electron effective mass and decrease in the electron mobility, and lead to a large enhance of the maximum doping level in GaInNAs doped with group VI donors. In addition, a striking asymmetry in the electrical activation of group IV and group VI donors can be attributed to mutual passivation process through formation of the nearest neighbor group-IV donor nitrogen pairs.

  5. Desynchronization in diluted neural networks

    SciTech Connect

    Zillmer, Ruediger; Livi, Roberto; Politi, Antonio; Torcini, Alessandro

    2006-09-15

    The dynamical behavior of a weakly diluted fully inhibitory network of pulse-coupled spiking neurons is investigated. Upon increasing the coupling strength, a transition from regular to stochasticlike regime is observed. In the weak-coupling phase, a periodic dynamics is rapidly approached, with all neurons firing with the same rate and mutually phase locked. The strong-coupling phase is characterized by an irregular pattern, even though the maximum Lyapunov exponent is negative. The paradox is solved by drawing an analogy with the phenomenon of 'stable chaos', i.e., by observing that the stochasticlike behavior is 'limited' to an exponentially long (with the system size) transient. Remarkably, the transient dynamics turns out to be stationary.

  6. XAFS in dilute magnetic semiconductors.

    PubMed

    Sun, Zhihu; Yan, Wensheng; Yao, Tao; Liu, Qinghua; Xie, Yi; Wei, Shiqiang

    2013-10-14

    X-Ray absorption fine structure (XAFS) spectroscopy has experienced a rapid development in the last four decades and has proved to be a powerful structure characterization technique in the study of local environments in condensed matter. In this article, we first introduce the XAFS basic principles including theory, data analysis and experiment in some detail. Then we attempt to make a review on the applications of XAFS to the study of atomic and electronic structure in dilute magnetic semiconductor (DMS) systems. The power of XAFS in characterizing this interesting material system, such as determining the occupation sites and distribution of the dopants, detecting the presence of metal clusters or secondary phases, as well as identifying the defect types and dopant valence, will be illuminated by selected examples. This review should be of interest both to newcomers in the DMS field and to an interdisciplinary community of researchers working in synthesis, characterization and utilization of DMS materials. PMID:23884341

  7. Comparison of Enrichment Broths for Supporting Growth of Shiga Toxin-Producing Escherichia coli.

    PubMed

    Stromberg, Zachary R; Lewis, Gentry L; Marx, David B; Moxley, Rodney A

    2015-08-01

    Detection of Shiga toxin-producing Escherichia coli (STEC) in complex sample matrices remains challenging. In an attempt to improve detection, nonselective and selective enrichment broths were compared as follows: (1) trypticase soy broth (TSB) was compared with TSB plus novobiocin, vancomycin, rifampicin, bile salts, and potassium tellurite (TSB-NVRBT) for supporting growth of STEC in pure culture; (2) E. coli broth (EC), TSB, and TSB plus bile salts (mTSB) were compared for enrichment of STEC O26, O45, O103, O104, O111, O121, O145, and O157 (STEC-8) in inoculated cattle fecal samples; (3) EC, TSB, and mTSB were compared for the detection of STEC-8 in inoculated cattle fecal samples. Fecal samples were inoculated with wild-type STEC-8 or nalidixic acid- or rifampicin-resistant derivatives of the same strains at 100, 1000, or 10,000 colony-forming units per gram (CFU/g) of feces. In pure culture, the mean STEC CFU/mL following enrichment in TSB was 1.17 log10 greater than that in TSB-NVRBT (P < 0.05). In inoculated fecal samples, EC enrichment yielded growth of STEC-8 (6.42 log10 CFU/g) that was significantly greater than in TSB (6.23 log10 CFU/g; P < 0.05), and numerically but not significantly greater than in mTSB (6.37 log10 CFU/g; P = 0.60). Wild-type STEC strains were detected in 43.8 % (21/48) of the samples enriched in EC and mTSB compared to 27.1 % (13/48) of the samples enriched in TSB (P = 0.15). Overall, STEC grew significantly better when enriched in EC compared to TSB. Modification of TSB by the addition of bile salts improved the growth and detection of STEC compared to TSB alone. PMID:25917502

  8. Quantification of N2-Carboxymethyl-2’-deoxyguanosine in Calf-thymus DNA and Cultured Human Kidney Epithelial Cells by Capillary HPLC-Tandem Mass Spectrometry Coupled with Stable Isotope-dilution Method

    PubMed Central

    Wang, Hongxia; Cao, Huachuan; Wang, Yinsheng

    2009-01-01

    Glyoxal is generated endogenously from the degradation of glucose and the oxidation of carbohydrates, lipids as well as the 2-deoxyribose moieties of DNA. Glyoxal is also widely used in industry and is present cigarette smoke and food. Glyoxal can conjugate with nucleobases and proteins to give advanced glycation end products. N2-carboxymethyl-2’-deoxyguanosine (N2-CMdG) and the cyclic 1,N2-glyoxal-dG are the major glyoxal adducts formed in DNA. In this study, we first assessed the stabilities of these two adducts. It turned out that 1,N2-glyoxal-dG was very unstable, with more than 70% of the adduct being decomposed to dG upon a 24-hr incubation at 37°C in phosphate buffered saline. However, N2-CMdG was very stable, less than 0.5% of the lesion was degraded to dG after a 7-day incubation under the same conditions. We further developed a sensitive capillary LC-ESI-MS/MS/MS coupled with stable isotope dilution method and quantified the formation of N2-CMdG in calf thymus DNA and 293T human kidney epithelial cells that were exposed to glyoxal and in calf thymus DNA treated with D-glucose. Our results showed that N2-CMdG was produced at 2–134 lesions per 106 nucleosides in calf thymus DNA when the surrounding glyoxal concentration was increased from 10 to 500 µM and approximately 3–27 lesions per 107 nucleosides while the D-glucose concentration changed from 2 to 50 mM. Furthermore, N2-CMdG was induced endogenously in 293T human kidney epithelial cells and exposure to glyoxal further stimulated the formation of this lesion; the level of this adduct ranged from 7 to 15 lesions per 108 nucleosides while the glyoxal concentration increased from 10 µM to 1.25 mM. Collectively, our results suggested that N2-CMdG might serve as a biomarker for glyoxal exposure. PMID:19968260

  9. Detailed Methodology and Implementation of a Semiautomated Serial Dilution Microtechnique for Antimicrobial Susceptibility Testing

    PubMed Central

    MacLowry, James D.; Jaqua, Mary J.; Selepak, Sally T.

    1970-01-01

    The detailed methodology and implementation of a semiautomatic microtechnique for performing serial dilution antimicrobial susceptibility studies are described. Quantitative susceptibility studies to a battery of antimicrobials are performed routinely on all significant clinical isolates. Results are reported as the minimal inhibitory concentration in micrograms per milliliter of broth. Guidelines relating standard doses of antimicrobials with expected blood and urine levels are presented to facilitate the use of the quantitative data. This microtechnique is used to measure serum and other body fluid levels of antimicrobial agents to document the level attained with a specific course of therapy. This technique is highly reproducible and has a high correlation with, and is at least 10 times faster than, standard glass tube techniques. PMID:4917462

  10. Gas dilution system results and application to acid rain utilities

    SciTech Connect

    Jolley-Souders, K.; Geib, R.; Dunn, C.

    1997-12-31

    In 1997, the United States EPA will remove restrictions preventing acid rain utilities from using gas dilution systems for calibration or linearity studies for continuous emissions monitoring, Test Method 205 in 40CFR51 requires that a gas dilution system must produce calibration gases whose measured values are within {+-}2% of predicted values. This paper presents the evaluation of the Environics/CalMat 2020 Dilution System for use in calibration studies. Internal studies show that concentrations generated by this unit are within {+-}0.5% of predicted values. Studies are being conducted by several acid rain utilities to evaluate the Environics/CalMat system using single minor component calibration standards. In addition, an internally generated study is being performed to demonstrate the system`s accuracy using a multi-component gas mixture. Data from these tests will be presented in the final version of the paper.

  11. Reusable chelating resins concentrate metal ions from highly dilute solutions

    NASA Technical Reports Server (NTRS)

    Bauman, A. J.; Weetal, H. H.; Weliky, N.

    1966-01-01

    Column chromatographic method uses new metal chelating resins for recovering heavy-metal ions from highly dilute solutions. The absorbed heavy-metal cations may be removed from the chelating resins by acid or base washes. The resins are reusable after the washes are completed.

  12. Activity coefficients of chlorophenols in water at infinite dilution

    SciTech Connect

    Tabai, S.; Rogalski, M.; Solimando, R.; Malanowski, S.K.

    1997-11-01

    The total pressure of aqueous solutions of chlorophenols was determined by a ebulliometric total pressure method for the aqueous solutions of phenol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol in the temperature range from 40 to 90 C. The activity coefficients at infinite dilution and the Henry constants were derived.

  13. Determination of Ideal Broth Formulations Needed to Prepare Hydrous Aluminum Oxide Microspheres via the Internal Gelation Process

    SciTech Connect

    Collins, Jack Lee; Pye, S. L.

    2009-02-01

    A simple test-tube methodology was used to determine optimum process parameters for preparing hydrous aluminum oxide microspheres by the internal gelation process. Broth formulations of aluminum, hexamethylenetetramine, and urea were found that can be used to prepare hydrous aluminum oxide gel spheres in the temperature range of 60-90 C. A few gel-forming runs were made in which microspheres were prepared with some of these formulations in order to equate the test-tube gelation times with actual gelation times. These preparations confirmed that the test-tube methodology is reliable for determining the ideal broths.

  14. Determination of Ideal Broth Formulations Needed to Prepare Hydrous Hafnium Oxide Microspheres via the Internal Gelation Process

    SciTech Connect

    Collins, Jack Lee; Hunt, Rodney Dale; Simmerman, S. G.

    2009-02-01

    A simple test-tube methodology was used to determine optimum process parameters for preparing hydrous hafnium oxide microspheres by the internal gelation process. Broth formulations of hafnyl chloride [HfOCl{sub 2}], hexamethylenetetramine, and urea were found that can be used to prepare hydrous hafnium oxide gel spheres in the temperature range of 70-90 C. A few gel-forming runs were made in which microspheres were prepared with some of these formulations in order to equate the test-tube gelation times with actual gelation times. These preparations confirmed that the test-tube methodology is reliable for determining the ideal broths.

  15. Efficient ethanol recovery from fermentation broths with integrated distillation-vapor permeation hybrid process

    EPA Science Inventory

    The energy demand of distillation-molecular sieve systems for ethanol recovery/dehydration can be significant, particularly for dilute solutions. An alternative hybrid process integrating vapor stripping (like a beer still) with vapor compression and a vapor permeation membrane s...

  16. Electrocoalescence based serial dilution of microfluidic droplets

    PubMed Central

    Bhattacharjee, Biddut; Vanapalli, Siva A.

    2014-01-01

    Dilution of microfluidic droplets where the concentration of a reagent is incrementally varied is a key operation in drop-based biological analysis. Here, we present an electrocoalescence based dilution scheme for droplets based on merging between moving and parked drops. We study the effects of fluidic and electrical parameters on the dilution process. Highly consistent coalescence and fine resolution in dilution factor are achieved with an AC signal as low as 10 V even though the electrodes are separated from the fluidic channel by insulator. We find that the amount of material exchange between the droplets per coalescence event is high for low capillary number. We also observe different types of coalescence depending on the flow and electrical parameters and discuss their influence on the rate of dilution. Overall, we find the key parameter governing the rate of dilution is the duration of coalescence between the moving and parked drop. The proposed design is simple incorporating the channel electrodes in the same layer as that of the fluidic channels. Our approach allows on-demand and controlled dilution of droplets and is simple enough to be useful for assays that require serial dilutions. The approach can also be useful for applications where there is a need to replace or wash fluid from stored drops. PMID:25379096

  17. The ring phenomenon of diluted blood droplets.

    PubMed

    Ramsthaler, Frank; Schlote, J; Wagner, C; Fiscina, J; Kettner, M

    2016-05-01

    Bloodstain pattern analysis is occasionally required in practical forensic casework. Misinterpretations may occur in cases in which diluted bloodstains are formed either within the course of the crime or during cleaning attempts after the original crime. The resulting pale or diluted aspect of the bloodstains may also be produced by passive serum separation. To differentiate between diluted and non-diluted stains and the artifacts of pure serum separation, dripping experiments were performed using droplets of multiple sizes and dilutions dripped onto common indoor and fabric surfaces. In addition, pools of blood of different volumes were applied to solid surfaces with different inclinations to determine the conditions and properties of serum separation. This study yielded morphological characteristics that enable differentiation between stains of diluted and non-diluted blood: a prominent ring phenomenon indicates dilution with water. To elucidate the underlying physical mechanism of particle distribution within a blood stain, photomicrographs were taken during the drying process. The so-called contact line pinning effect was identified as the formation mechanism of this ring phenomenon. Serum separation was highly dependent on the applied blood volume, the ambient temperature, the time elapsed since the initial deposition, and the degree of floor inclination. PMID:26718842

  18. DAVINCI a Dilute Aperture Coronagraph

    NASA Astrophysics Data System (ADS)

    Shao, Michael

    2009-01-01

    The motivation for DAVINCI was originally to make use of the technology developed for space interferometers like SIM to build a coronagraph from four 1.1m telescopes that was dramatically lower in cost than a 4 5m filled aperture offaxis coronagraph. Our initial studies through team X have shown this cost savings to be real. But a more careful analysis showed that DAVINCI would have an inner working angle of 35mas a factor of 2 smaller than a 2 lambda/D 4 meter coronagraph or 70m external occulter, resulting in a 10X increase in the number of potential Earth-Clone targets. DAVINCI uses a nulling interferometer as a coronagraph, a nulling interferometer is one the few coronagraph architectures that are compatible with segmented and dilute aperture telescopes. Combined with a post coronagraph wavefront sensor several ultra-demanding tolerances of conventional coronagraphs can be relaxed by factors of 100. The post coronagraph wavefront sensor is also much less affected by local and exozodi background than wavefront sensors that use the science camera as the wavefront sensor. The post coronagraph interferometer is also used on ground based extreme AO coronagraphs, GPI, and P1640.

  19. Color-dilution alopecia in dogs.

    PubMed

    Kim, Jae Hoon; Kang, Kyung Il; Sohn, Hyun Joo; Woo, Gye Hyeong; Jean, Young Hwa; Hwang, Eui Kyung

    2005-09-01

    Color-dilution alopecia is a relatively uncommon hereditary skin disease seen in "Blue" and other color-diluted dogs. This syndrome is associated with a color-dilution gene. The initial clinical signs are the gradual onset of a dry, dull and poor hair coat quality. Hair shafts and hair regrowth are poor, and follicular papules may develop and progress to frank comedones. Hair loss and comedo formation are usually most severe on the trunk, especially color-diluted area on the skin. Six cases of color-dilution alopecia are reported in 3 months to 10 years old dogs. The breeds of dogs are blue Doberman Pinscher, Miniature Pinscher, Dachshund, and Schnauzer. Grossly, extensive partial hair loss was seen on the skin. Histopathologically, the epidermis is relatively normal but may be hyperplastic. Hair follicles are characterized by atrophy and distortion. Heavily clumped melanin is present in the epidermis, dermis and hair follicles. PMID:16131833

  20. Replica bounds for diluted non-Poissonian spin systems

    NASA Astrophysics Data System (ADS)

    Franz, Silvio; Leone, Michele; Lucio Toninelli, Fabio

    2003-10-01

    In this paper we extend replica bounds and free energy subadditivity arguments to diluted spin-glass models on graphs with arbitrary, non-Poissonian degree distribution. The new difficulties specific of this case are overcome introducing an interpolation procedure that stresses the relation between interpolation methods and the cavity method. As a byproduct we obtain self-averaging identities that generalize the Ghirlanda-Guerra ones to the multi-overlap case.

  1. Plate-Dilution Frequency Technique for Assay of Microbial Ecology1

    PubMed Central

    Harris, R. F.; Sommers, L. E.

    1968-01-01

    The plate-dilution frequency technique described facilitates simultaneous enumeration of a wide range of physiologically different microorganisms in complex systems with a precision comparable to dilution tube (most probable number) methods. Replicate microsamples are inoculated from each member of a dilution series onto areas delineated on plates of prepoured solid media; the plates are incubated, and the occurrence of growth or specific biochemical transformation is recorded for each inoculated area. Microbial enumeration is accomplished by reference to appropriate tables. Details of the experimental procedures are described, and tables are presented from which microbial numbers with 95% confidence limits can be obtained and compared for significant difference directly for 10-fold and 4-fold dilution series. Results of experiments in which microbial populations were estimated simultaneously by the plate-dilution frequency and conventional plate count methods are compared. The potential of the technique for broad-spectrum microbial assay is also discussed. Images Fig. 1 PMID:4868864

  2. Supplementing chicken broth with monosodium glutamate reduces energy intake from high fat and sweet snacks in middle-aged healthy women.

    PubMed

    Imada, Toshifumi; Hao, Susan Shuzhen; Torii, Kunio; Kimura, Eiichiro

    2014-08-01

    Monosodium L-glutamate (MSG) and inosine monophosphate-5 (IMP) are flavor enhancers for umami taste. However, their effects on appetite and food intake are not well-researched. The objective of the current study was to test their additions in a broth preload on subsequent appetite ratings, energy intake and food choice. Eighty-six healthy middle-aged women with normal body weight received three preload conditions on 3 test days 1 week apart - a low-energy chicken flavor broth (200 ml) as the control preload, and broths with added MSG alone (0.5 g/100 ml, MSG broth) or in combination with IMP (0.05 g/100 ml) (MSG+ broth) served as the experimental conditions. Fifteen minutes after preload administration subjects were provided an ad libitum testing meal which consisted of 16 snacks varying in taste and fat content. MSG and MSG+ enhanced savory taste and broth properties of liking and pleasantness. In comparison with control, the MSG preload resulted in less consumption of total energy, as well as energy from sweet and high-fat snacks. Furthermore, MSG broth preload reduced added sugar intake. These findings were not observed after MSG+ preload. Appetite ratings were not different across the three preloads. Results suggest a potential role of MSG addition to a low-energy broth preload in subsequent energy intake and food choice. This trial was registered at clinicaltrials.gov as NCT01761045. PMID:24768895

  3. Recovery of acids from anaerobic acidification broth by liquid-liquid extraction.

    PubMed

    Alkaya, Emrah; Kaptan, Serkan; Ozkan, Leyla; Uludag-Demirer, Sibel; Demirer, Göksel N

    2009-11-01

    In this study, anaerobic acidification of sugar beet processing wastes and subsequent liquid-liquid extraction of produced fermentation metabolites were investigated. The aim of extraction experiments was to asses the influence of pH and extractant (trioctylphosphine oxide (TOPO) in kerosene) concentrations on the recovery of volatile fatty acids (VFAs) from fermentation broth. The effect of TOPO in kerosene concentration was as crucial as the effect of pH on the recovery of VFAs via extraction. Consequently, pH 2.5 was determined as optimum. At this pH, percent recoveries of VFAs were changed from 43% to 98%, depending on the type of the acid extracted (acetic, butyric, propionic and valeric acids) and the concentration of TOPO in kerosene (5-20%). As the concentration of TOPO in kerosene was increased, efficiency of extraction was increased. As a result, highest VFA recoveries (61-98%) were observed at 20% TOPO in kerosene with distribution ratio values ranging between 1.54 and 40.79. At pH 2.5, the increase in TOPO concentration directly increased the chemical oxygen demand (COD) removal efficiencies, as it does for total VFA recovery. Up to 72% COD removals were achieved, at 20% TOPO in kerosene at pH 2.5, while the removal efficiencies remained between 19% and 22% at pH 5.5. PMID:19747710

  4. Purification of chondroitin precursor from Escherichia coli K4 fermentation broth using membrane processing.

    PubMed

    Schiraldi, Chiara; Carcarino, Immacolata Loredana; Alfano, Alberto; Restaino, Odile Francesca; Panariello, Andrea; De Rosa, Mario

    2011-04-01

    Recently the possibility of producing the capsular polysaccharide K4, a fructosylated chondroitin, in fed-batch experiments was assessed. In the present study, a novel downstream process to obtain chondroitin from Escherichia coli K4 fermentation broth was developed. The process is simple, scalable and economical. In particular, downstream procedures were optimized with a particular aim of purifying a product suitable for further chemical modifications, in an attempt to develop a biotechnological platform for chondroitin sulfate production. During process development, membrane devices (ultrafiltration/diafiltration) were exploited, selecting the right cassette cut-offs for different phases of purification. The operational conditions (cross-flow rate and transmembrane pressure) used for the process were determined on an ÄKTA cross-flow instrument (GE Healthcare, USA), a lab-scale automatic tangential flow filtration system. In addition, parameters such as selectivity and throughput were calculated based on the analytical quantification of K4 and defructosylated K4, as well as the major contaminants. The complete downstream procedure yielded about 75% chondroitin with a purity higher than 90%. PMID:21381202

  5. Dried bonito broth improves cognitive function via the histaminergic system in mice.

    PubMed

    Nozawa, Yoshizu; Mimura, Masako; Yamada, Keiko; Sugita, Mayu; Shibakusa, Tetsuro; Koyama, Naoto

    2014-01-01

    Bonito extract, i.e., dried bonito broth (DBB), has been reported to counteract mental fatigue and to increase performance in a simple calculation task, but the mechanism by which DBB increases task performance is not known. The brain neurotransmitter histamine is biosynthesized only from histidine in the tuberomammillary nucleus. Histamine neurons are projected to almost all areas of the cerebral cortex, and histamine has various behavioral and neurobiological functions, particularly in recognition memory. Here we used a mouse model to investigate the effects of the oral ingestion of DBB, which contains abundant histidine, as well as the ingestion of histidine on cognitive function. In a retention trial of novel object recognition test, the administration of 1.6 g/kg of DBB and 500 mg/kg of histidine significantly increased the animals' exploratory behavior toward a novel object, and that these agents significantly increased the spontaneous alternation behavior ratio in a Y-maze under conditions of scopolamine-induced amnesia, which induced learning and memory impairment. These results suggested the improvement of spatial short-term working memory in a scopolamine amnesia model, as well as the strengthening of visual cognitive function by a single ingestion of DBB and histidine. Interestingly, the administration of αFMH, which is an inhibitor of histamine biosynthesis, eliminated the increase in the spontaneous alternation behavior ratio by DBB ingestion in the scopolamine-induced amnesia model, suggesting that DBB may improve working memory impairment via activation of the histaminergic neuron system. PMID:25355438

  6. Oil and air dispersion in a simulated fermentation broth as a function of mycelial morphology.

    PubMed

    Lucatero, Savidra; Larralde-Corona, Claudia Patricia; Corkidi, Gabriel; Galindo, Enrique

    2003-01-01

    The culture conditions of a multiphase fermentation involving morphologically complex mycelia were simulated in order to investigate the influence of mycelial morphology (Trichoderma harzianum) on castor oil and air dispersion. Measurements of oil drops and air bubbles were obtained using an image analysis system coupled to a mixing tank. Complex interactions of the phases involved could be clearly observed. The Sauter diameter and the size distributions of drops and bubbles were affected by the morphological type of biomass (pellets or dispersed mycelia) added to the system. Larger oil drop sizes were obtained with dispersed mycelia than with pellets, as a result of the high apparent viscosity of the broth, which caused a drop in the power drawn, reducing oil drop break-up. Unexpectedly, bubble sizes observed with dispersed mycelia were smaller than with pellets, a phenomenon which can be explained by the segregation occurring at high biomass concentrations with the dispersed mycelia. Very complex oil drops were produced, containing air bubbles and a high number of structures likely consisting of small water droplets. Bubble location was influenced by biomass morphology. The percentage (in volume) of oil-trapped bubbles increased (from 32 to 80%) as dispersed mycelia concentration increased. A practically constant (32%) percentage of oil-trapped bubbles was observed with pelleted morphology at all biomass concentrations. The results evidenced the high complexity of phases interactions and the importance of mycelial morphology in such processes. PMID:12675561

  7. Performance of serum-free broth media for growth of Renibacterium salmoninarum

    USGS Publications Warehouse

    Starliper, C.E.; Schill, W.B.; Mathias, J.

    1998-01-01

    Growth of Renibacterium salmoninarum was compared in 14 different broth media; 13 serum-free, and 1 that contained newborn calf serum, KDM2+M. Supplementation with 1% v/v R. salmoninarum MCO4M metabolite was evaluated for 6 of the media that do not utilize it as part of their ingredients. Viable cells were enumerated on Days 10, 20, and 30 post inoculation to evaluate performance. The experiment was repeated 3 times using high, low, and medium (trials 1 to 3, respectively) cell concentrations as inoculum. In general there was no optimal medium and all performed well. The choice of which to employ depends on the ease of preparation and presence of certain ingredients that might affect subsequent assays. In trials 2 and 3, the pH was estimated using test papers at the same time as cells were counted. Maximum pH increase occurred with KDM2+M and those media containing charcoal. For most media, a simple pH determination could be used as a means to check that growth has occurred in a culture, particularly if charcoal was added directly to the media and a visual inspection could not be made to detect growth.

  8. Performance of serum-free broth media for growth of Renibacterium salmoninarum.

    PubMed

    Starliper, C E; Schill, W B; Mathias, J

    1998-09-11

    Growth of Renibacterium salmoninarum was compared in 14 different broth media; 13 serum-free, and 1 that contained newborn calf serum, KDM2+M. Supplementation with 1% v/v R. salmoninarum MCO4M metabolite was evaluated for 6 of the media that do not utilize it as part of their ingredients. Viable cells were enumerated on Days 10, 20, and 30 post inoculation to evaluate performance. The experiment was repeated 3 times using high, low, and medium (trials 1 to 3, respectively) cell concentrations as inoculum. In general there was no optimal medium and all performed well. The choice of which to employ depends on the ease of preparation and presence of certain ingredients that might affect subsequent assays. In trials 2 and 3, the pH was estimated using test papers at the same time as cells were counted. Maximum pH increase occurred with KDM2+M and those media containing charcoal. For most media, a simple pH determination could be used as a means to check that growth has occurred in a culture, particularly if charcoal was added directly to the media and a visual inspection could not be made to detect growth. PMID:9789976

  9. Multi-center and multi-method evaluation of in vitro activities of ceftaroline against S. aureus.

    PubMed

    Koeth, Laura M; Apfalter, Petra; Becker, Karsten; Gesu, Giovanni; Martínez-Martínez, Luis; Lahiri, Sushmita D; Alm, Richard A; Ambler, Jane; Iaconis, Joseph

    2016-08-01

    This five-site study was performed to assess the reproducibility of ceftaroline MIC and disk results for Staphylococcus aureus. Three commercial broth microdilution, three gradient diffusion and ceftaroline 5μg disk diffusion methods were compared to a reference broth microdilution method against challenge isolates (n = 41) and isolates collected at four European sites (n = 30/site). For four MIC methods (Sensititre and three gradient diffusion methods), 99.0% of consolidated MIC results were within +/- 1 dilution of the reference MIC. Categorical agreement rates based on EUCAST breakpoints for the challenge isolates were 75.6-100% and for disk testing were 78.0-92.7%. There was no clear distinction between isolates with MIC results of 1 and 2mg/L with regard to variation in MIC or molecular genotyping results. The addition of an intermediate category for isolates with MIC results of 2mg/L would help to identify these isolates as borderline susceptible/non-susceptible isolates. PMID:27233426

  10. Noninvasive photoacoustic measurement of the composite indicator dilution curve for cardiac output estimation

    PubMed Central

    Kang, DongYel; Huang, Qiaojian; Li, Youzhi

    2015-01-01

    Recently, the measurement of indicator dilution curves using a photoacoustic (PA) technology was reported, which showed promising results on the noninvasive estimation of cardiac output (CO) that is an important hemodynamic parameter useful in various clinical situations. However, in clinical practice, measuring PA indicator dilution curves from an arterial blood vessel requires an ultrasound transducer array capable of focusing on the targeted artery. This causes several challenges on the clinical translation of the PA indicator dilution method, such as high sensor cost and complexity. In this paper, we theoretically derived that a composite PA indicator dilution curve simultaneously measured from both arterial and venous blood vessels can be used to estimate CO correctly. The ex-vivo and in-vivo experimental results with a flat ultrasound transducer verified the developed theory. We believe this new concept would overcome the main challenges on the clinical translation of the noninvasive PA indicator dilution technology. PMID:25780743

  11. A helium-3/helium-4 dilution cryocooler for operation in zero gravity

    NASA Technical Reports Server (NTRS)

    Hendricks, John B.

    1988-01-01

    This research effort covered the development of He-3/He-4 dilution cryocooler cycles for use in zero gravity. The dilution cryocooler is currently the method of choice for producing temperatures below 0.3 Kelvin in the laboratory. However, the current dilution cryocooler depends on gravity for their operation, so some modification is required for zero gravity operation. In this effort, we have demonstrated, by analysis, that the zero gravity dilution cryocooler is feasible. We have developed a cycle that uses He-3 circulation, and an alternate cycle that uses superfluid He-4 circulation. The key elements of both cycles were demonstrated experimentally. The development of a true 'zero-gravity' dilution cryocooler is now possible, and should be undertaken in a follow-on effort.

  12. Real-Time Identification of Bacteria and Candida Species in Positive Blood Culture Broths by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry▿

    PubMed Central

    Ferroni, Agnès; Suarez, Stéphanie; Beretti, Jean-Luc; Dauphin, Brunhilde; Bille, Emmanuelle; Meyer, Julie; Bougnoux, Marie-Elisabeth; Alanio, Alexandre; Berche, Patrick; Nassif, Xavier

    2010-01-01

    Delays in the identification of microorganisms are a barrier to the establishment of adequate empirical antibiotic therapy of bacteremia. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) allows the identification of microorganisms directly from colonies within minutes. In this study, we have adapted and tested this technology for use with blood culture broths, thus allowing identification in less than 30 min once the blood culture is detected as positive. Our method is based on the selective recovery of bacteria by adding a detergent that solubilizes blood cells but not microbial membranes. Microorganisms are then extracted by centrifugation and analyzed by MALDI-TOF-MS. This strategy was first tested by inoculating various bacterial and fungal species into negative blood culture bottles. We then tested positive patient blood or fluid samples grown in blood culture bottles, and the results obtained by MALDI-TOF-MS were compared with those obtained using conventional strategies. Three hundred twelve spiked bottles and 434 positive cultures from patients were analyzed. Among monomicrobial fluids, MALDI-TOF-MS allowed a reliable identification at the species, group, and genus/family level in 91%, 5%, and 2% of cases, respectively, in 20 min. In only 2% of these samples, MALDI-TOF MS did not yield any result. When blood cultures were multibacterial, identification was improved by using specific databases based on the Gram staining results. MALDI-TOF-MS is currently the fastest technique to accurately identify microorganisms grown in positive blood culture broths. PMID:20237092

  13. Numerical modeling for dilute and dense sprays

    NASA Technical Reports Server (NTRS)

    Chen, C. P.; Kim, Y. M.; Shang, H. M.; Ziebarth, J. P.; Wang, T. S.

    1992-01-01

    We have successfully implemented a numerical model for spray-combustion calculations. In this model, the governing gas-phase equations in Eulerian coordinate are solved by a time-marching multiple pressure correction procedure based on the operator-splitting technique. The droplet-phase equations in Lagrangian coordinate are solved by a stochastic discrete particle technique. In order to simplify the calculation procedure for the circulating droplets, the effective conductivity model is utilized. The k-epsilon models are utilized to characterize the time and length scales of the gas phase in conjunction with turbulent modulation by droplets and droplet dispersion by turbulence. This method entails random sampling of instantaneous gas flow properties and the stochastic process requires a large number of computational parcels to produce the satisfactory dispersion distributions even for rather dilute sprays. Two major improvements in spray combustion modelings were made. Firstly, we have developed a probability density function approach in multidimensional space to represent a specific computational particle. Secondly, we incorporate the Taylor Analogy Breakup (TAB) model for handling the dense spray effects. This breakup model is based on the reasonable assumption that atomization and drop breakup are indistinguishable processes within a dense spray near the nozzle exit. Accordingly, atomization is prescribed by injecting drops which have a characteristic size equal to the nozzle exit diameter. Example problems include the nearly homogeneous and inhomogeneous turbulent particle dispersion, and the non-evaporating, evaporating, and burning dense sprays. Comparison with experimental data will be discussed in detail.

  14. Revisiting the Dilution Procedure Used To Manipulate Microbial Biodiversity in Terrestrial Systems

    PubMed Central

    Yan, Yan; Kuramae, Eiko E.; Klinkhamer, Peter G. L.

    2015-01-01

    It is hard to assess experimentally the importance of microbial diversity in soil for the functioning of terrestrial ecosystems. An approach that is often used to make such assessment is the so-called dilution method. This method is based on the assumption that the biodiversity of the microbial community is reduced after dilution of a soil suspension and that the reduced diversity persists after incubation of more or less diluted inocula in soil. However, little is known about how the communities develop in soil after inoculation. In this study, serial dilutions of a soil suspension were made and reinoculated into the original soil previously sterilized by gamma irradiation. We determined the structure of the microbial communities in the suspensions and in the inoculated soils using 454-pyrosequencing of 16S rRNA genes. Upon dilution, several diversity indices showed that, indeed, the diversity of the bacterial communities in the suspensions decreased dramatically, with Proteobacteria as the dominant phylum of bacteria detected in all dilutions. The structure of the microbial community was changed considerably in soil, with Proteobacteria, Bacteroidetes, and Verrucomicrobia as the dominant groups in most diluted samples, indicating the importance of soil-related mechanisms operating in the assembly of the communities. We found unique operational taxonomic units (OTUs) even in the highest dilution in both the suspensions and the incubated soil samples. We conclude that the dilution approach reduces the diversity of microbial communities in soil samples but that it does not allow accurate predictions of the community assemblage during incubation of (diluted) suspensions in soil. PMID:25888175

  15. Quantitative Analysis by Isotopic Dilution Using Mass Spectroscopy: The Determination of Caffeine by GC-MS.

    ERIC Educational Resources Information Center

    Hill, Devon W.; And Others

    1988-01-01

    Describes a laboratory technique for quantitative analysis of caffeine by an isotopic dilution method for coupled gas chromatography-mass spectroscopy. Discusses caffeine analysis and experimental methodology. Lists sample caffeine concentrations found in common products. (MVL)

  16. Determination of Ideal Broth Formulations Needed to Prepare Hydrous Cerium Oxide Microspheres via the Internal Gelation Process

    SciTech Connect

    Collins, Jack Lee; Chi, Anthony

    2009-02-01

    A simple test tube methodology was used to determine optimum process parameters for preparing hydrous cerium oxide microspheres via the internal gelation process.1 Broth formulations of cerium ammonium nitrate [(NH4)2Ce(NO3)6], hexamethylenetetramine, and urea were found that can be used to prepare hydrous cerium oxide gel spheres in the temperature range of 60 to 90 C. A few gel-forming runs were made in which microspheres were prepared with some of these formulations to be able to equate the test-tube gelation times to actual gelation times. These preparations confirmed that the test-tube methodology is reliable for determining the ideal broth formulations.

  17. Inactivation of Staphylococcus aureus and Salmonella enteritidis in tryptic soy broth and caviar samples by high pressure processing.

    PubMed

    Fioretto, F; Cruz, C; Largeteau, A; Sarli, T A; Demazeau, G; El Moueffak, A

    2005-08-01

    We studied the action of high pressure processing on the inactivation of two foodborne pathogens, Staphylococcus aureus ATCC 6538 and Salmonella enteritidis ATCC 13076, suspended in a culture medium and inoculated into caviar samples. The baroresistance of the two pathogens in a tryptic soy broth suspension at a concentration of 10(8)-10(9) colony-forming units/ml was tested for continuous and cycled pressurization in the 150- to 550-MPa range and for 15-min treatments at room temperature. The increase of cycle number permitted the reduction of the pressure level able to totally inactivate both microorganisms in the tryptic soy broth suspension, whereas the effect of different procedure times on complete inactivation of the microorganisms inoculated into caviar was similar. PMID:16082468

  18. Epidemiology of Salmonella sp. in California cull dairy cattle: prevalence of fecal shedding and diagnostic accuracy of pooled enriched broth culture of fecal samples

    PubMed Central

    Abu Aboud, Omran A.; Adaska, John M.; Williams, Deniece R.; Rossitto, Paul V.; Champagne, John D.; Lehenbauer, Terry W.; Atwill, Robert; Li, Xunde

    2016-01-01

    Background The primary objective of this cross-sectional study was to estimate the crude, seasonal and cull-reason stratified prevalence of Salmonella fecal shedding in cull dairy cattle on seven California dairies. A secondary objective was to estimate and compare the relative sensitivity (Se) and specificity (Sp) for pools of 5 and 10 enriched broth cultures of fecal samples for Salmonella sp. detection. Methods Seven dairy farms located in the San Joaquin Valley of California were identified and enrolled in the study as a convenience sample. Cull cows were identified for fecal sampling once during each season between 2014 and 2015, specifically during spring, summer, fall, and winter, and 10 cows were randomly selected for fecal sampling at the day of their sale. In addition, study personnel completed a survey based on responses of the herd manager to questions related to the previous four month’s herd management. Fecal samples were frozen until testing for Salmonella. After overnight enrichment in liquid broth, pools of enrichment broth (EBP) were created for 5 and 10 samples. All individual and pooled broths were cultured on selective media with putative Salmonella colonies confirmed by biochemical testing before being serogrouped and serotyped. Results A total of 249 cull cows were enrolled into the study and their fecal samples tested for Salmonella. The survey-weighted period prevalence of fecal shedding of all Salmonella sp. in the cull cow samples across all study herds and the entire study period was 3.42% (N = 249; SE 1.07). The within herd prevalence of Salmonella shed in feces did not differ over the four study seasons (P = 0.074). The Se of culture of EBP of five samples was 62.5% (SE = 17.12), which was not statistically different from the Se of culture of EBP of 10 (37.5%, SE = 17.12, P = 0.48). The Sp of culture of EBP of five samples was 95.24% (SE = 3.29) and for pools of 10 samples was 100.00% (SE = 0). There was no statistical difference

  19. Submerged-Culture Mycelia and Broth of the Maitake Medicinal Mushroom Grifola frondosa (Higher Basidiomycetes) Alleviate Type 2 Diabetes-Induced Alterations in Immunocytic Function.

    PubMed

    Chen, Ya-Hui; Lee, Chien-Hsing; Hsu, Tai-Hao; Lo, Hui-Chen

    2015-01-01

    Type 2 Diabetes mellitus (T2DM), a disease with impaired glucose, protein and lipid metabolism, low-grade chronic inflammation, and immune dysfunction, is a global public health crisis. We previously demonstrated that Grifola frondosa has bioactivities in improving glycemic responses in diabetic rats. Herein, we investigated the immunomodulatory effects of the submerged-culture mycelia and broth of G. frondosa on the peripheral blood cells (PBL) and splenocytes. Male Wistar rats were administered with saline (normal rats) or streptozotocin plus nicotinamide (T2DM rats) and were intragastrically administered with placebo, fermented mycelia, broth, or mycelia plus broth (1 g kg-1 day-1) for two weeks. In normal rats, ingestion of mycelia significantly decreased monocytes and ingestion of mycelia and broth significantly decreased the productions of interferon (IFN)-γ and interleukin (IL)-4 from the PBL and splenocytes. In T2DM rats, ingestion of mycelia, broth, and mycelia plus broth significantly alleviated the increases in 2 h postprandial blood glucose and the productions of IFN-γ from the T-leukocytes, IL-4, and IL-6 from the monocytes and IL-4 from the T-splenocytes, as well as significantly improved the productions of tumor-necrosis factor-α from the macrophages. In conclusion, submerged-culture mycelia and broth of G. frondosa may decrease cell-medicated immunity in normal rats and improve hyperglycemia and diabetes-induced alterations in cell-medicated and innate immunities in T2DM rats. PMID:26349512

  20. Ultra scale-down prediction using microwell technology of the industrial scale clarification characteristics by centrifugation of mammalian cell broths.

    PubMed

    Tait, A S; Aucamp, J P; Bugeon, A; Hoare, M

    2009-10-01

    This article describes how a combination of an ultra scale-down (USD) shear device feeding a microwell centrifugation plate may be used to provide a prediction of how mammalian cell broth will clarify at scale. In particular a method is described that is inherently adaptable to a robotic platform and may be used to predict how the flow rate and capacity (equivalent settling area) of a centrifuge and the choice of feed zone configuration may affect the solids carry over in the supernatant. This is an important consideration as the extent of solids carry over will determine the required size and lifetime of a subsequent filtration stage or the passage of fine particulates and colloidal material affecting the performance and lifetime of chromatography stages. The extent of solids removal observed in individual wells of a microwell plate during centrifugation is shown to correlate with the vertical and horizontal location of the well on the plate. Geometric adjustments to the evaluation of the equivalent settling area of individual wells (Sigma(M)) results in an improved prediction of solids removal as a function of centrifuge capacity. The USD centrifuge settling characteristics need to be as for a range of equivalent flow rates as may be experienced at an industrial scale for a machine of different shear characteristics in the entry feed zone. This was shown to be achievable with two microwell-plate based measurements and the use of varying fill volumes in the microwells to allow the rapid study of a fivefold range of equivalent flow rates (i.e., at full scale for a particular industrial centrifuge) and the effect of a range of feed configurations. The microwell based USD method was used to examine the recovery of CHO-S cells, prepared in a 5 L reactor, at different points of growth and for different levels of exposure to shear post reactor. The combination of particle size distribution measurements of the cells before and after shear and the effect of shear on the

  1. Detection of Echinococcus multilocularis in faeces by nested PCR with the use of diluted DNA samples.

    PubMed

    Karamon, J

    2014-01-01

    The aim of this study was to choose the optimal variant of PCR examination of faeces to detect Echinococcus multilocularis infection which would allow to reduce the influence of different inhibitors in faeces. The investigation was carried out by comparison of 3 different methods of DNA isolation from faeces and different DNA dilutions used in PCR. Thirty five intestines of red foxes were used. Small intestines were examined by the sedimentation and counting technique (SCT). Faeces were collected from the rectum for PCR and flotation. DNA were isolated with the use of 3 different methods. Two methods were dedicated for faeces: method 1 (M1)--for larger samples and method 2 (M2) - for standard samples. The third method, method 3 (M3), was not dedicated for faeces. DNA samples were tested by nested PCR in 6 variants: not diluted (1/1) and 5 diluted (1/2.5, 1/5, 1/10. 1/20, 1/40). E. multilocularis was found by SCT in 18 from 35 (51.4%) intestines. Taenia-type eggs were detected only in 20.0% of faecal samples. In PCR the highest number of positive results (45.7%) were obtained during examination of DNA isolated by M1 method, and then 40.0% and 34.3%, respectively, for M2 and M3. In some samples positive results in PCR were obtained only in diluted DNA. For example, 8 from 12 positive samples isolated by M3 method gave the PCR negative results in non-diluted DNA and positive only after dilution 1:2.5, 1:10 or 1:20. Also 3 samples isolated by methods dedicated for stool gave positive results only after DNA dilution. The investigation has revealed that in copro-PCR for detection of E. multilocularis infection additional using of diluted DNA (besides non diluted) can avoid false negative results causing by PCR inhibition. In the best method of DNA isolation (M1), the use of non diluted DNA sample together with diluted in proportion 1:10 seems to be optimal. PMID:24724473

  2. Extraction of natural red colorants from the fermented broth of Penicillium purpurogenum using aqueous two-phase polymer systems.

    PubMed

    Santos-Ebinuma, Valéria Carvalho; Lopes, André Moreni; Pessoa, Adalberto; Teixeira, Maria Francisca Simas

    2015-01-01

    Safety concerns related to the increasing and widespread application of synthetic coloring agents have increased the demand for natural colorants. Fungi have been employed in the production of novel and safer colorants. In order to obtain the colorants from fermented broth, suitable extraction systems must be developed. Aqueous two-phase polymer systems (ATPPS) offer a favorable chemical environment and provide a promising alternative for extracting and solubilizing these molecules. The aim of this study was to investigate the partitioning of red colorants from the fermented broth of Penicillium purpurogenum using an ATPPS composed of poly(ethylene glycol) (PEG) and sodium polyacrylate (NaPA). Red colorants partitioned preferentially to the top (PEG-rich phase). In systems composed of PEG 6,000 g/mol/NaPA 8,000 g/mol, optimum colorant partition coefficient (KC ) was obtained in the presence of NaCl 0.1 M (KC  = 10.30) while the PEG 10,000 g/mol/NaPA 8,000 g/mol system in the presence of Na2 SO4 0.5 M showed the highest KC (14.78). For both polymers, the mass balance (%MB) and yield in the PEG phase (%ηTOP ) were close to 100 and 79%, respectively. The protein selectivity in all conditions evaluated ranged from 2.0-3.0, which shows a suitable separation of the red colorants and proteins present in the fermented broth. The results suggest that the partitioning of the red colorants is dependent on both the PEG molecular size and salt type. Furthermore, the results obtained support the potential application of ATPPS as the first step of a purification process to recover colorants from fermented broth of microorganisms. PMID:26097197

  3. Effect of cycle time on fungal morphology, broth rheology, and recombinant enzyme productivity during pulsed addition of limiting carbon source.

    PubMed

    Bhargava, Swapnil; Wenger, Kevin S; Rane, Kishore; Rising, Vanessa; Marten, Mark R

    2005-03-01

    For many years, high broth viscosity has remained a key challenge in large-scale filamentous fungal fermentations. In previous studies, we showed that broth viscosity could be reduced by pulsed addition of limiting carbon during fed-batch fermentation. The objective in this study was to determine how changing the frequency of pulsed substrate addition affects fungal morphology, broth rheology, and recombinant enzyme productivity. To accomplish this, a series of duplicate fed-batch fermentations were performed in 20-L fermentors with a recombinant glucoamylase producing strain of Aspergillus oryzae. The total cycle time for substrate pulsing was varied over a wide range (30-2,700 s), with substrate added only during the first 30% of each cycle. As a control, a fermentation was conducted with continuous substrate feeding, and in all fermentations the same total amount of substrate was added. Results show that the total biomass concentration remained relatively unaltered, while a substantial decrease in the mean projected area of fungal elements (i.e., average size) was observed with increasing cycle time. This led to reduced broth viscosity and increased oxygen uptake rate. However, high values of cycle time (i.e., 900-2,700 s) showed a significant increase in fungal conidia formation and significantly reduced recombinant enzyme productivity, suggesting that the fungi channeled substrate to storage compounds rather than to recombinant protein. In addition to explaining the effect of cycle time on fermentation performance, these results may aid in explaining the discrepancies observed on scale-up to larger fermentors. PMID:15643626

  4. Cortical attractor network dynamics with diluted connectivity.

    PubMed

    Rolls, Edmund T; Webb, Tristan J

    2012-01-24

    The connectivity of the cerebral cortex is diluted, with the probability of excitatory connections between even nearby pyramidal cells rarely more than 0.1, and in the hippocampus 0.04. To investigate the extent to which this diluted connectivity affects the dynamics of attractor networks in the cerebral cortex, we simulated an integrate-and-fire attractor network taking decisions between competing inputs with diluted connectivity of 0.25 or 0.1, and with the same number of synaptic connections per neuron for the recurrent collateral synapses within an attractor population as for full connectivity. The results indicated that there was less spiking-related noise with the diluted connectivity in that the stability of the network when in the spontaneous state of firing increased, and the accuracy of the correct decisions increased. The decision times were a little slower with diluted than with complete connectivity. Given that the capacity of the network is set by the number of recurrent collateral synaptic connections per neuron, on which there is a biological limit, the findings indicate that the stability of cortical networks, and the accuracy of their correct decisions or memory recall operations, can be increased by utilizing diluted connectivity and correspondingly increasing the number of neurons in the network, with little impact on the speed of processing of the cortex. Thus diluted connectivity can decrease cortical spiking-related noise. In addition, we show that the Fano factor for the trial-to-trial variability of the neuronal firing decreases from the spontaneous firing state value when the attractor network makes a decision. This article is part of a Special Issue entitled "Neural Coding". PMID:21875702

  5. Aggregation In Heavy Water Micellar Dilute Solutions Of Three Nonionic Classic Surfactants: C10E7 AND C12E7 And C14E7 Study By SANS Method

    NASA Astrophysics Data System (ADS)

    Aldona, Rajewska

    2010-01-01

    Three nonionic classic surfactants C10E7 (heptaethylene glycol monodecyl ether) and C12E7 (heptaethylene glycol monododecyl ether) and C14E7 (heptaethylene glycol monotetradecyl ether) in water solutions were investigated for concentration c = 0.5% (dilute regime) at temperatures t = 6°, 10°, 15°, 20°, 25°, 30° and 35° C with two methods—tensiometric and small-angle neutron scattering ( SANS ) on SANS diffractometer "Yellow Submarine" at Budapest Neutron Center, Budapest ( Hungary ) and SANS spectrometer ("YuMO") of the IBR-2 on pulsed neutron source at FLNP, JINR in Dubna ( Russia ). Measurements have covered Q range from 8 10-3 to 0.4 Å-1. The micellar solutions were prepared in D2O since the contrast between the micelles and the solvent in neutron experiments is better with D2O than with H2O. It was obtained as the result that the shape of micelles changes depending on surfactant concentration and temperature. At lower concentrations and temperatures micelles are ellipsoids but at higher concentrations and temperature are rather cylinders. For calculation and approximation results from SANS experiments was used program PCG 2.0 of Glatter O. and co-workers from University of Graz (Austria).

  6. Declining ecosystem health and the dilution effect.

    PubMed

    Khalil, Hussein; Ecke, Frauke; Evander, Magnus; Magnusson, Magnus; Hörnfeldt, Birger

    2016-01-01

    The "dilution effect" implies that where species vary in susceptibility to infection by a pathogen, higher diversity often leads to lower infection prevalence in hosts. For directly transmitted pathogens, non-host species may "dilute" infection directly (1) and indirectly (2). Competitors and predators may (1) alter host behavior to reduce pathogen transmission or (2) reduce host density. In a well-studied system, we tested the dilution of the zoonotic Puumala hantavirus (PUUV) in bank voles (Myodes glareolus) by two competitors and a predator. Our study was based on long-term PUUV infection data (2003-2013) in northern Sweden. The field vole (Microtus agrestis) and the common shrew (Sorex araneus) are bank vole competitors and Tengmalm's owl (Aegolius funereus) is a main predator of bank voles. Infection probability in bank voles decreased when common shrew density increased, suggesting that common shrews reduced PUUV transmission. Field voles suppressed bank vole density in meadows and clear-cuts and indirectly diluted PUUV infection. Further, Tengmalm's owl decline in 1980-2013 may have contributed to higher PUUV infection rates in bank voles in 2003-2013 compared to 1979-1986. Our study provides further evidence for dilution effect and suggests that owls may have an important role in reducing disease risk. PMID:27499001

  7. Breakdown of Cell Wall Nanostructure in Dilute Acid Pretreated Biomass

    SciTech Connect

    Pingali, Sai Venkatesh; Urban, Volker S; Heller, William T; McGaughey, Joseph; O'Neill, Hugh Michael; Foston, Marcus B; Myles, Dean A A; Ragauskas, Arthur J; Evans, Barbara R

    2010-01-01

    The generation of bioethanol from lignocellulosic biomass holds great promise for renewable and clean energy production. A better understanding of the complex mechanisms of lignocellulose breakdown during various pretreatment methods is needed to realize this potential in a cost and energy efficient way. Here, we use small-angle neutron scattering (SANS) to characterize morphological changes in switchgrass lignocellulose across molecular to sub-micron length scales resulting from the industrially-relevant dilute acid pretreatment method. Our results demonstrate that dilute acid pretreatment increases the cross-sectional radius of the crystalline cellulose fibril. This change is accompanied by removal of hemicellulose and the formation of Rg ~ 135 lignin aggregates. The structural signature of smooth cell wall surfaces is observed at length scales larger than 1000 , and it remains remarkably invariable during pretreatment. This study elucidates the interplay of the different biomolecular components in the break down process of switchgrass by dilute acid pretreatment. The results are important for the development of efficient strategies of biomass to biofuel conversion.

  8. 40 CFR 1065.240 - Dilution air and diluted exhaust flow meters.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... meter, a thermal-mass meter, an averaging Pitot tube, or a hot-wire anemometer. (c) Flow conditioning... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Dilution air and diluted exhaust flow...) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Flow-Related...

  9. 40 CFR 1065.240 - Dilution air and diluted exhaust flow meters.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... meter, a thermal-mass meter, an averaging Pitot tube, or a hot-wire anemometer. (c) Flow conditioning... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Dilution air and diluted exhaust flow...) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Flow-Related...

  10. 40 CFR 1065.240 - Dilution air and diluted exhaust flow meters.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... meter, a thermal-mass meter, an averaging Pitot tube, or a hot-wire anemometer. (c) Flow conditioning... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Dilution air and diluted exhaust flow...) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Flow-Related...

  11. 40 CFR 1065.240 - Dilution air and diluted exhaust flow meters.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... meter, a thermal-mass meter, an averaging Pitot tube, or a hot-wire anemometer. (c) Flow conditioning... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Dilution air and diluted exhaust flow...) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Flow-Related...

  12. 40 CFR 1065.240 - Dilution air and diluted exhaust flow meters.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... meter, a thermal-mass meter, an averaging Pitot tube, or a hot-wire anemometer. (c) Flow conditioning... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Dilution air and diluted exhaust flow...) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Flow-Related...

  13. Spin dynamics in paramagnetic diluted magnetic semiconductors

    NASA Astrophysics Data System (ADS)

    Phan, Van-Nham; Tran, Minh-Tien

    2015-10-01

    Microscopic properties of low-energy spin dynamics in diluted magnetic semiconductor are addressed in a framework of the Kondo lattice model including random distribution of magnetic dopants. Based on the fluctuation-dissipation theorem, we derive an explicit dependence of the spin diffusion coefficient on the single-particle Green function which is directly evaluated by dynamical mean-field theory. In the paramagnetic state, the magnetic scattering has been manifested to suppress spin diffusion. In agreement with other ferromagnet systems, we also point out that the spin diffusion in diluted magnetic semiconductors at small carrier concentration displays a monotonic 1 /T -like temperature dependence. By investigating the spin diffusion coefficient on a wide range of the model parameters, the obtained results have provided a significant scenario to understand the spin dynamics in the paramagnetic diluted magnetic semiconductors.

  14. The Carlina-type diluted telescope. Stellar fringes on Deneb

    NASA Astrophysics Data System (ADS)

    Le Coroller, H.; Dejonghe, J.; Hespeels, F.; Arnold, L.; Andersen, T.; Deram, P.; Ricci, D.; Berio, P.; Blazit, A.; Clausse, J.-M.; Guillaume, C.; Meunier, J. P.; Regal, X.; Sottile, R.

    2015-01-01

    Context. The performance of interferometers has been much increased over the past ten years. But the number of observable objects is still limited by the low sensitivity and imaging capability of the current facilities. Studies have been conducted with the aim to propose a new generation of interferometers. Aims: The Carlina concept studied at the Haute-Provence Observatory consists of an optical interferometer configured as a diluted version of the Arecibo radio telescope: above the diluted primary mirror made of fixed co-spherical segments, a helium balloon or cables that are suspended between two mountains and/or pylons carry a gondola containing the focal optics. This concept does not require delay lines. Methods: Since 2003, we have been building a technical demonstrator of this diluted telescope. The main goals of this project were to find opto-mechanical solutions to stabilize the optics attached to cables at several tens of meters above the ground, and to characterize this diluted telescope under real conditions. In 2012, we obtained metrology fringes, and co-spherized the primary mirrors within one micron accuracy. In 2013, we tested the whole optical train: servo loop, metrology, and the focal gondola. Results: We obtained stellar fringes on Deneb in September 2013. We here present the characteristics of these observations: quality of the guiding, signal-to-noise ratio reached, and possible improvements for a future system. Conclusions: By detecting fringes on Deneb, we confirm that the entire system conceptually has worked correctly. It also proves that when the primary mirrors are aligned using the metrology system, we can directly record fringes in the focal gondola, even in blind operation. It is an important step that demonstrates the feasibility of building a diluted telescope using cables strained between cliffs or pylons. Carlina, like the Multiple Mirror Telescope (MMT) or Large Binocular Telescope (LBT), could be one of the first members of a

  15. Automatic dilution gaging of rapidly varying flow

    USGS Publications Warehouse

    Duerk, M.D.

    1983-01-01

    The analysis showed that the discharges measured by dye-dilution techniques were generally within ± 10 percent of the discharges determined from ratings established by current-meter measurements. Larger differences were noted at the start of and on the rising limb of four hydrographs. Of the 20 storms monitored, dilution measurements on 17 were of acceptable accuracy. Peak discharges from the open-channel site ranged from 0 to 12 percent departures from the existing rating whereas the comparison of peak discharge at the storm sewer site ranged from 0 to 5 percent departures from the existing rating.

  16. Film quality in relation to deposition conditions of {ital a}-SI:H films deposited by the {open_quote}{open_quote}hot wire{close_quote}{close_quote} method using highly diluted silane

    SciTech Connect

    Molenbroek, E.C.; Mahan, A.H.; Johnson, E.J.; Gallagher, A.C.

    1996-05-01

    The deposition parameter space has been extensively explored using the hot wire technique with 1{percent} SiH{sub 4} in He as a source gas. To achieve reasonable deposition rates despite the high dilution, the filament was positioned at 1{endash}2 cm from the substrate. This short distance introduced a large nonuniformity across the substrate in deposition rate as well as in film properties. These spatial variations were used to analyze which factors in the deposition determine film quality. Radiation from the filament as well as deposition rate cannot explain the large variation in film properties, leaving gas-phase reactions of Si and H from the hot filament as the primary cause. It is clear that radicals evaporated from the filament must undergo gas-phase reactions with SiH{sub 4} before deposition in order to produce high-quality material. Thus, conditions such as increasing the chamber pressure or going to a heavier carrier gas increase the fraction of radicals that can react before reaching the substrate and, therefore, improve the film quality. However, such conditions also enhance multiple radical reactions before such radicals reach the substrate and this can have a negative effect on film quality: this is attributed to gas-phase nucleation with incorporation of conglomerates. The gas-phase chemistry is quite different from that of plasma-enhanced decomposition in that no disilane or trisilane is formed in significant quantities. This, and the dependence on pressure, indicates that the pathway for formation of these heavier particles is radical{endash}radical reactions. {copyright} {ital 1996 American Institute of Physics.}

  17. Comparison of a homemade blood culture broth containing a papain digest of liver, with four commercially available media for the isolation of anaerobes from simulated paediatric blood cultures.

    PubMed Central

    Hunt, G H; Price, E H

    1982-01-01

    The recovery of small inocula of fastidious organisms, mainly non-sporing anaerobes, was studied in simulated paediatric blood culture experiments where only 1.5 ml of blood was added to each broth. A 25 ml homemade Queen Elizabeth Hospital medium (QEH medium) containing a papain digest of liver showed the best overall performance during the first four days of incubation; this medium was also satisfactory for maintenance of the majority of the organisms tested for longer than one week. LAB M Fastidious Anaerobe Broth (75 ml) with thymidine, also showed early isolation and satisfactory survival of most organisms. Difco Thiol broth, 50 ml with Liquoid, yielded early growth of the three strains of Bacteroides fragilis tested and maintained these organisms well; however, variable results were obtained with some other organisms in Difco Thiol media. Southern Group Brewer's thioglycollate broth (80 ml) gave the least satisfactory performance. PMID:6752208

  18. Trace determination of zinc by substoichiometric isotope dilution analysis

    SciTech Connect

    Sandhya, D.; Priya, S.; Subramanian, M.O.S.

    1996-09-01

    A radiometric method based on substoichiometric isotope dilution analysis using 1,10-phenanthroline and a substoichiometric amount of eosin was developed for determining trace amounts of zinc. Evaluation of various metal ion interferences shows that as little as 0.2 {mu}g Zn could be determined in an aqueous-phase volume of 60 mL. The method has been successfully applied to the determination of Zn in city waste incineration ash, cadmium metal, Fourts-B tablets, Boro-plus ointment, and magnesium alloy samples. 12 refs., 3 figs., 3 tabs.

  19. STABLE ISOTOPE DILUTION FOR HAZARDOUS WASTE INCINERATION

    EPA Science Inventory

    The report gives results of a project to determine if a proposed catalytic exchange procedure could be adapted to produce the labeled analog materials necessary for isotope dilution gas chromatography/mass spectrometry (GC/MS) analysis. It is related to a general evaluation of th...

  20. LAKE RESTORATION BY DILUTION: MOSES LAKE, WASHINGTON

    EPA Science Inventory

    Dilution water, low in macronutrients, was added to Moses Lake on three occasions in 1977 and once in 1978 during the spring-summer period. The addition resulted in reducing the annual average inflow concentration of phosphorus from about 130-140 micrograms/l to 100 micrograms/l....

  1. Dry Dilution Refrigerator with High Cooling Power

    NASA Astrophysics Data System (ADS)

    Uhlig, K.

    2008-03-01

    We present the construction concept and cooling capacity measurements of a 3,4He dilution refrigerator (DR), which was pre-cooled by a commercial pulse tube refrigerator (PTR). No cryogens are needed for the operation of this type of cryostat. The condensation of the helium mash was done in an integrated Joule-Thomson circuit, which was part of the dilution unit. The composition of the dilution unit was standard, but its components (still, heat exchangers, mixing chamber) were designed for high 3He flow. For thermometry, calibrated RuO chip resistance thermometers were available. In order to condense the mixture before an experiment, the fridge was operated like a Joule-Thomson liquefier with a relatively high inlet pressure (4 bar), where the liquid fraction of the circulating 3,4He mixture was accumulated in the dilution unit. The condensation took about 2 hours, and after 2 more hours of running, the temperature of the mixing chamber approached its minimum temperature of 10 mK. The maximum flow rate of the fridge was 1 mmol/s, and the refrigeration capacity of the mixing chamber was 700 μW at 100 mK. High cooling capacity, ease of operation and reliability distinguish this type of milli-Kelvin cooler.

  2. Phase Transition of Diluted Magnetic Semiconductor

    NASA Astrophysics Data System (ADS)

    Li, M. K.; Lee, S. J.; Yuldashev, S. U.; Ihm, G.; Kang, T. W.

    2011-12-01

    Three types of phase transitions in diluted magnetic semiconductor, first-order, second-order and mixed-order, are found in theory. Especially the mixed type transition shows two steps transition and novel specific heat property. Specific heat properties disclose a possible meta ferromagnetic phase confirmed by the experimental qualitative result.

  3. Sulfuric Acid and Water: Paradoxes of Dilution

    ERIC Educational Resources Information Center

    Leenson, I. A.

    2004-01-01

    On equilibrium properties of aqueous solutions of sulfuric acid, Julius Thomsen has marked that the heat evolved on diluting liquid sulfuric acid with water is a continuous function of the water used, and excluded absolutely the acceptance of definite hydrates as existing in the solution. Information about thermochemical measurement, a discussion…

  4. Declining ecosystem health and the dilution effect

    PubMed Central

    Khalil, Hussein; Ecke, Frauke; Evander, Magnus; Magnusson, Magnus; Hörnfeldt, Birger

    2016-01-01

    The “dilution effect” implies that where species vary in susceptibility to infection by a pathogen, higher diversity often leads to lower infection prevalence in hosts. For directly transmitted pathogens, non-host species may “dilute” infection directly (1) and indirectly (2). Competitors and predators may (1) alter host behavior to reduce pathogen transmission or (2) reduce host density. In a well-studied system, we tested the dilution of the zoonotic Puumala hantavirus (PUUV) in bank voles (Myodes glareolus) by two competitors and a predator. Our study was based on long-term PUUV infection data (2003–2013) in northern Sweden. The field vole (Microtus agrestis) and the common shrew (Sorex araneus) are bank vole competitors and Tengmalm’s owl (Aegolius funereus) is a main predator of bank voles. Infection probability in bank voles decreased when common shrew density increased, suggesting that common shrews reduced PUUV transmission. Field voles suppressed bank vole density in meadows and clear-cuts and indirectly diluted PUUV infection. Further, Tengmalm’s owl decline in 1980–2013 may have contributed to higher PUUV infection rates in bank voles in 2003–2013 compared to 1979–1986. Our study provides further evidence for dilution effect and suggests that owls may have an important role in reducing disease risk. PMID:27499001

  5. Modeling the behavior of Listeria monocytogenes during enrichment in half Fraser broth; impact of pooling and the duration of enrichment on the detection of L. monocytogenes in food.

    PubMed

    Augustin, Jean-Christophe; Kalmokoff, Martin; Ells, Timothy; Favret, Sandra; Desreumaux, Jennifer; Decourseulles Brasseur, Emilie; Gnanou Besse, Nathalie

    2016-12-01

    A stochastic model describing the growth of Listeria monocytogenes during enrichment in half Fraser was developed for the purpose of estimating the effects of modifications to the first enrichment step of the EN ISO 11290-1 detection method. Information pertaining to the variability of growth rates, physiological state of the cell, and the behavior of individual cells contaminating the food were obtained from previously published studies. We used this model to investigate the impact of pooling enrichment broths (wet pooling) on the performance of the standard method. For validation of the model, the numbers of L. monocytogenes occurring in 88 naturally contaminated foods following pre-enrichment were compared to model-simulated microbial counts. The model was then used to perform simulations representative of the natural contamination observed for smoked salmon in the European baseline survey of 2010-2011. The model-estimated L. monocytogenes levels following individual enrichment or following the pooling of five broths where only one would be contaminated were compared. The model indicated a 10% loss of method sensitivity resulting from wet pooling. The model also predicted a 5% decrease in the sensitivity of the method when the duration of the enrichment was reduced from 24 to 22 h. PMID:27554154

  6. Thermal dilution measurement of cardiac output in dogs using an analog computer.

    PubMed

    Hendriks, F F; Schipperheyn, J J; Quanjer, P H

    1978-01-01

    Thermal dilution cardiac output determinations in dogs were compared to simultaneously performed Fick oxygen measurements. The purpose of this study was to validate in dog experiments a method for thermal dilution measurement which employs a double-thermistor catheter combined with an automatic computer as described by Olsson et al. Dilution and injectate temperature are entered directly into the calculation. The method does not employ logarithmic extrapolation, integration of the dilution signal being terminated when a preset cut-off level is reached. Errors due to recirculation, thermal capacitance of the right heart and heat exchange with the catheter's dead space require the use of an empirically derived correction factor, which in dogs was found to be significantly different from the factor used for human thermal dilution curves. With the appropriate cut-off level and correction factor a good agreement was found between the results of the thermal dilution and the Fick method. The regression equation for 47 experiments was found to be COtd = 0.95 COFick + 0.08; the correlation coefficient was 0.94. PMID:728031

  7. Impact of preheating on the behavior of Listeria monocytogenes in a broth that mimics Camembert cheese composition.

    PubMed

    Helloin, E; Bouttefroy, A; Gay, M; Phan Thanh, L

    2003-02-01

    The effect of preheating on the survival of L. monocytogenes in Richard's broth, which mimics the composition of Camembert cheese composition, was examined. Experiments were carried out to reproduce contamination of cheese with environmental heat-stressed cells of L. monocytogenes surviving hot-cleaning procedures. Cells in mid-log phase were heated for 30 min at 56 degrees C before being inoculated into Richard's broth. The pHs and temperatures of Richard's broth were chosen to recreate the conditions of curd dripping (pH 5, 25 degrees C), of the beginning of cheese ripening (pH 5, 12 degrees C), and of the beginning (pH 5, 4 degrees C) and the end (pH 7, 4 degrees C) of cheese storage. Immediately after heat treatment, the viability loss was especially high for strain 306715, which exhibited only 0.6% +/- 0.2% survival, compared with 22% +/- 8.7% for strain EGD. The percentages of the surviving heated cells that were injured were 93% +/- 8% for strain 306715 and 98% +/- 3% for strain EGD. The destruction of the surviving L. monocytogenes cells was accelerated when they encountered the pH and temperature conditions of Camembert cheese during manufacturing, ripening, and cold storage (pH 5 at 25, 12, and 4 degrees C, respectively). The multiplication of the surviving heated cells was retarded under favorable growth conditions similar to those of storage by the distributor and the consumer (pH 7 at 4 and 12 degrees C, respectively). PMID:12597487

  8. Comparative Evaluation of Colistin Susceptibility Testing Methods among Carbapenem-Nonsusceptible Klebsiella pneumoniae and Acinetobacter baumannii Clinical Isolates.

    PubMed

    Dafopoulou, Konstantina; Zarkotou, Olympia; Dimitroulia, Evangelia; Hadjichristodoulou, Christos; Gennimata, Vasiliki; Pournaras, Spyros; Tsakris, Athanasios

    2015-08-01

    We compared six colistin susceptibility testing (ST) methods on 61 carbapenem-nonsusceptible Klebsiella pneumoniae (n = 41) and Acinetobacter baumannii (n = 20) clinical isolates with provisionally elevated colistin MICs by routine ST. Colistin MICs were determined by broth microdilution (BMD), BMD with 0.002% polysorbate 80 (P80) (BMD-P80), agar dilution (AD), Etest, Vitek2, and MIC test strip (MTS). BMD was used as the reference method for comparison. The EUCAST-recommended susceptible and resistant breakpoints of ≤2 and >2 μg/ml, respectively, were applied for both K. pneumoniae and A. baumannii. The proportions of colistin-resistant strains were 95.1, 77, 96.7, 57.4, 65.6, and 98.4% by BMD, BMD-P80, AD, Etest, MTS, and Vitek2, respectively. The Etest and MTS methods produced excessive rates of very major errors (VMEs) (39.3 and 31.1%, respectively), while BMD-P80 produced 18% VMEs, AD produced 3.3% VMEs, and Vitek2 produced no VMEs. Major errors (MEs) were rather limited by all tested methods. These data show that gradient diffusion methods may lead to inappropriate colistin therapy. Clinical laboratories should consider the use of automated systems, such as Vitek2, or dilution methods for colistin ST. PMID:26014928

  9. Comparative Evaluation of Colistin Susceptibility Testing Methods among Carbapenem-Nonsusceptible Klebsiella pneumoniae and Acinetobacter baumannii Clinical Isolates

    PubMed Central

    Dafopoulou, Konstantina; Zarkotou, Olympia; Dimitroulia, Evangelia; Hadjichristodoulou, Christos; Gennimata, Vasiliki; Tsakris, Athanasios

    2015-01-01

    We compared six colistin susceptibility testing (ST) methods on 61 carbapenem-nonsusceptible Klebsiella pneumoniae (n = 41) and Acinetobacter baumannii (n = 20) clinical isolates with provisionally elevated colistin MICs by routine ST. Colistin MICs were determined by broth microdilution (BMD), BMD with 0.002% polysorbate 80 (P80) (BMD-P80), agar dilution (AD), Etest, Vitek2, and MIC test strip (MTS). BMD was used as the reference method for comparison. The EUCAST-recommended susceptible and resistant breakpoints of ≤2 and >2 μg/ml, respectively, were applied for both K. pneumoniae and A. baumannii. The proportions of colistin-resistant strains were 95.1, 77, 96.7, 57.4, 65.6, and 98.4% by BMD, BMD-P80, AD, Etest, MTS, and Vitek2, respectively. The Etest and MTS methods produced excessive rates of very major errors (VMEs) (39.3 and 31.1%, respectively), while BMD-P80 produced 18% VMEs, AD produced 3.3% VMEs, and Vitek2 produced no VMEs. Major errors (MEs) were rather limited by all tested methods. These data show that gradient diffusion methods may lead to inappropriate colistin therapy. Clinical laboratories should consider the use of automated systems, such as Vitek2, or dilution methods for colistin ST. PMID:26014928

  10. 2-layer based microfluidic concentration generator by hybrid serial and volumetric dilutions.

    PubMed

    Lee, Kangsun; Kim, Choong; Kim, Youngeun; Jung, Keunhui; Ahn, Byungwook; Kang, Ji Yoon; Oh, Kwang W

    2010-04-01

    We present a 2-layer based microfluidic concentration generator by a hybrid of a serial and a volumetric dilution for dose-response experiments in drug screening. The hybrid dilution method using 2-layer based microfluidic network significantly reduces the total number of cascaded serial dilution stages. The proposed strategy is capable of generating a large number of universal stepwise monotonic concentrations with a wide range of logarithmic and linear scales. We have studied an equivalent electrical circuit to that of the 2-layer based microfluidic network, where the only variable parameter is channel length. We have designed a microfluidic dilution generator simultaneously covering 14 doses with a combination of 4-order logarithmic and 4-point linear concentrations. The design has been verified by a commercial circuit analysis software (e.g., P-Spice) for the electrical circuit analysis and a computational fluid dynamics software (e.g., CFD-ACE+) for the microfluidic circuit analysis. As a real-life application of the proposed dilution generator, we have successfully performed a dose-response experiment using MCF-7 human breast cancer cells. We expect that the proposed dilution method will be useful to study not only high throughput drug screening but also optimization in biology, chemistry, medicine, and material sciences. PMID:20077018

  11. Detection of Burkholderia pseudomallei in Sputum using Selective Enrichment Broth and Ashdown’s Medium at Kampong Cham Provincial Hospital, Cambodia

    PubMed Central

    Nhem, Somary; Letchford, Joanne; Meas, Chea; Thann, Sovanndeth; McLaughlin, James C.; Baron, Ellen Jo; West, T. Eoin

    2015-01-01

    Melioidosis, infection caused by Burkholderia pseudomallei, is increasingly reported in Cambodia. We hypothesized that implementation of an enhanced sputum testing protocol in a provincial hospital diagnostic microbiology laboratory would increase detection of B. pseudomallei. We tested 241 sputum specimens that were deemed acceptable for culture, comparing culture in selective enrichment broth followed by sub-culture on Ashdown’s medium to standard culture methods. Two specimens (0.8%) were positive for B. pseudomallei using the enhanced protocol whereas one specimen (0.4%) was positive using standard methods. Given the low numbers of positive specimens, we could not conclusively determine the utility of the enhanced sputum testing protocol. However, the ramifications of identification of  B. pseudomallei are substantial, and the benefit of the enhanced testing protocol may be more apparent in patients selected based on risk factors and clinical presentation. Promoting clinician awareness of the infection and encouraging utilization of diagnostic microbiology services are also likely to be important factors in facilitating identification of melioidosis. PMID:25717370

  12. Using isotope dilution mass spectrometry to determine aqueous trichloroacetic acid

    SciTech Connect

    Norwood, D.L.; Christman, R.F.; Johnson, J.D.; Hass, J.R.

    1986-01-01

    The development, verification, and application of a method based on isotope-dilution gas chromatography-mass spectrometry to determine aqueous trichloroacetic acid (TCAA) at the micrograms per litre level are described. The simultaneous determination of aqueous chloroform is also demonstrated. Trichloroacetic acid is shown to be a significant by-product of the chlorination of raw waters in the laboratory and to constitute a large fraction of the total organic halide (TOX) formed. Analysis of finished-water samples indicated that TCAA, like trihalomethanes is ubiquitous. Positive correlations exist between the levels of TCAA in laboratory-chlorinated raw waters and in finished waters and measured TOX.

  13. Scaling of Greenwood Peierls conductance on a diluted square lattice

    NASA Astrophysics Data System (ADS)

    Schwalm, William; Schmitz, Albert

    The modified rectangle lattice of Dhar is a bond-diluted square lattice. The structure is self-similar and finitely ramified, like a fractal. Nevertheless certain discrete Schrödinger equation Green functions for the modified rectangle are known in closed form in the infinite lattice limit and the spectrum is continuous. By standard transfer matrix renormalization methods we present a study scaling properties of the Greenwood Peierls conductance distribution across the lattice with one dimensional lead wires attached as a function of lattice size and of additional disorder of several types.

  14. Dilution jet mixing program, supplementary report

    NASA Technical Reports Server (NTRS)

    Srinivasan, R.; White, C.

    1986-01-01

    The velocity and temperature distributions predicted by a 3-D numerical model and experimental measurements are compared. Empirical correlations for the jet velocity trajectory developed are presented. The measured velocity distributions for all test cases of phase through phase 3 are presented in the form of contour and oblique plots. quantification of the effects of the following on the jet mixing characteristics with a confined crossflow are: (1) orifice geometry momentum flux ratio and density ratio; (2) nonuniform mainstream temperature and velocity profiles upstream of dilution orifices; (3) cold versus hot jet injection; (4) cross-stream flow are a convergence as encountered in practical dilution zone geometries; (5) 2-D slot versus circular orifices; (6) discrete noncirculcer orifices; (7) single-sided versus opposed jets; (8) single row of jets.

  15. Kinetic model for dilute traffic flow

    NASA Astrophysics Data System (ADS)

    Balouchi, Ashkan; Browne, Dana A.

    The flow of traffic represents a many-particle non-equilibrium problem with important practical consequences. Traffic behavior has been studied using a variety of approaches, including fluid dynamics models, Boltzmann equation, and recently cellular automata (CA). The CA model for traffic flow that Nagel and Schreckenberg (NS) introduced can successfully mimic many of the known features of the traffic flow. We show that in the dilute limit of the NS model, where vehicles exhibit free flow, cars show significant nearest neighbor correlation primarily via a short-range repulsion. introduce an approximate analytic model to describe this dilute limit. We show that the distribution of the distance between consecutive vehicles obeys a drift-diffusion equation. We compared this model with direct simulations. The steady state solution and relaxation of this model agrees well with direct simulations. We explore how this model breaks down as the transition to jams occurs.

  16. Effect of Sex on Flavor-related and Functional Compounds in Freeze-dried Broth Made from Korean Native Chicken

    PubMed Central

    Jayasena, Dinesh D.; Jung, Samooel; Alahakoon, Amali U.; Nam, Ki Chang

    2014-01-01

    Studies on the flavour characteristics of meat-based broth, quantification of flavour-related and functional compounds, and factors affecting the availability of such compounds are minimal. The present study was designed to determine the effects of sex on flavor-related and functional compounds in freeze-dried broth (FDB) made from Korean native chickens (KNC). Male and female KNC from a commercial strain (WoorimatdagTM) were reared under similar commercial conditions. FDB was separately prepared using male and female birds aged 100 d (six birds of each sex) and analyzed for nucleotide, free amino acid, betaine, carnitine, carnosine, anserine, and creatine contents, and fatty acid composition. The levels of betaine, carnitine and creatine in FDB were not significantly different between the two sexes (p>0.05) in KNC. Carnosine and anserine were not detected in FDB samples. However, FDB from female chickens had significantly higher inosine-5-monophosphate and arachidonic acid contents than did FDB from male chickens. FDB prepared with male KNC contained higher levels of inosine, linoleic acid, glycine, alanine, lysine, and serine (p<0.05). However, glutamic acid, oleic acid, and DHA were present in comparable amounts (p>0.05) in FDB made from male and female KNC. Our findings suggest that the sex of KNC has significant effect on the contents of flavor-related compounds, but not functional compounds. PMID:26761282

  17. Isolation of natural red colorants from fermented broth using ionic liquid-based aqueous two-phase systems.

    PubMed

    Ventura, Sónia P M; Santos-Ebinuma, Valéria C; Pereira, Jorge F B; Teixeira, Maria F S; Pessoa, Adalberto; Coutinho, João A P

    2013-05-01

    There is a growing demand for natural colorants. This is prompting the search for new alternative and "benign" separation systems allowing higher recoveries, extraction yields, and selectivities. This work investigates the use of aqueous two-phase systems (ATPS) based on ionic liquids as extraction processes for the recovery of red colorants from the fermented broth of Penicillium purpurogenum DPUA 1275. Several ATPS based on quaternary ammonium and imidazolium were studied in this work aiming at separating the red colorants produced from the remaining colorants and contaminant proteins present in the fermented broth. The results suggest that the red colorants can be isolated by an appropriate manipulation of some of the process conditions, such as the use of quaternary ammonium with short alkyl chains, alkaline media, and short tie-line lengths (extraction point systems with lower concentrations of ionic liquid). These conditions allow large partition coefficients for the red colorants (K red = 24.4 ± 2.3), high protein removal (60.7 ± 2.8 %) and selectivity parameters (S red/prot = 10.05). PMID:23455697

  18. 3D magnetometer for a dilution refrigerator

    NASA Astrophysics Data System (ADS)

    Uchaikin, S.; Likhachev, A.; Cioata, F.; Perminov, I.; Sanghera, H.; Singh, I.; Spear, P.; Chavez, P.; Han, X.; Petroff, C.; Rich, C.

    2012-12-01

    In this report, we describe a development of a three dimensional system for measurements of magnetic field at a wide temperature range of 300K-4K. The system is based on 8 AMR sensors and allows for control of the magnetic environment in a dilution refrigerator during the cool down of a superconducting processor. With a low noise signal processing electronics and a special sensor saturation circuit, a magnetic induction resolution below of 1 nT was achieved.

  19. Nutritional assessment by isotope dilution analysis of body composition

    SciTech Connect

    Szeluga, D.J.; Stuart, R.K.; Utermohlen, V.; Santos, G.W.

    1984-10-01

    The three components of body mass, body cell mass (BCM), extracellular fluid (ECF), and fat + extracellular solids (ECS: bone, tendon, etc) can be quantified using established isotope dilution techniques. With these techniques, total body water (TBW) and ECF are measured using 3H/sub 2/O and /sup 82/Bromine, respectively, as tracers. BCM is calculated from intracellular fluid (ICF) where ICF . TBW - ECF. Fat + ECS is estimated as: body weight - (BCM + ECF). TBW and ECF can be determined by either of two calculation methods, one requiring several timed plasma samples (extrapolation method) and one requiring a single plasma sample and a 4-h urine collection (urine-corrected method). The comparability of the two calculation methods was evaluated in 20 studies in 12 bone marrow transplant recipients. We found that for determination of TBW and ECF there was a very strong linear relationship (r2 greater than 0.98) between the calculation methods. Further comparisons (by t test, 2-sided) indicated that for the determination of ECF, the methods were not significantly (p greater than 0.90) different; however, TBW determined by the urine-corrected method was slightly (0.1 to 6%), but significantly (p less than 0.01) greater than that determined by the extrapolation method. Therefore, relative to the extrapolation method, the urine-corrected method ''over-estimates'' BCM and ''under-estimates'' fat + ECS since determination of these compartment sizes depends on measurement of TBW. We currently use serial isotope dilution studies to monitor the body composition changes of patients receiving therapeutic nutritional support.

  20. Optimization and validation of a method for the determination of the refractive index of milk serum based on the reaction between milk and copper(II) sulfate to detect milk dilutions.

    PubMed

    Rezende, Patrícia Sueli; do Carmo, Geraldo Paulo; Esteves, Eduardo Gonçalves

    2015-06-01

    We report the use of a method to determine the refractive index of copper(II) serum (RICS) in milk as a tool to detect the fraudulent addition of water. This practice is highly profitable, unlawful, and difficult to deter. The method was optimized and validated and is simple, fast and robust. The optimized method yielded statistically equivalent results compared to the reference method with an accuracy of 0.4% and quadrupled analytical throughput. Trueness, precision (repeatability and intermediate precision) and ruggedness are determined to be satisfactory at a 95.45% confidence level. The expanded uncertainty of the measurement was ±0.38°Zeiss at the 95.45% confidence level (k=3.30), corresponding to 1.03% of the minimum measurement expected in adequate samples (>37.00°Zeiss). PMID:25863391

  1. Dilution physics modeling: Dissolution/precipitation chemistry

    SciTech Connect

    Onishi, Y.; Reid, H.C.; Trent, D.S.

    1995-09-01

    This report documents progress made to date on integrating dilution/precipitation chemistry and new physical models into the TEMPEST thermal-hydraulics computer code. Implementation of dissolution/precipitation chemistry models is necessary for predicting nonhomogeneous, time-dependent, physical/chemical behavior of tank wastes with and without a variety of possible engineered remediation and mitigation activities. Such behavior includes chemical reactions, gas retention, solids resuspension, solids dissolution and generation, solids settling/rising, and convective motion of physical and chemical species. Thus this model development is important from the standpoint of predicting the consequences of various engineered activities, such as mitigation by dilution, retrieval, or pretreatment, that can affect safe operations. The integration of a dissolution/precipitation chemistry module allows the various phase species concentrations to enter into the physical calculations that affect the TEMPEST hydrodynamic flow calculations. The yield strength model of non-Newtonian sludge correlates yield to a power function of solids concentration. Likewise, shear stress is concentration-dependent, and the dissolution/precipitation chemistry calculations develop the species concentration evolution that produces fluid flow resistance changes. Dilution of waste with pure water, molar concentrations of sodium hydroxide, and other chemical streams can be analyzed for the reactive species changes and hydrodynamic flow characteristics.

  2. THE ANISOTROPIC TRANSPORT EFFECTS ON DILUTE PLASMAS

    SciTech Connect

    Devlen, Ebru

    2011-04-20

    We examine the linear stability analysis of a hot, dilute, and differentially rotating plasma by considering anisotropic transport effects. In dilute plasmas, the ion Larmor radius is small compared with its collisional mean free path. In this case, the transport of heat and momentum along the magnetic field lines becomes important. This paper presents a novel linear instability that may be more powerful and greater than ideal magnetothermal instability and ideal magnetorotational instability in the dilute astrophysical plasmas. This type of plasma is believed to be found in the intracluster medium (ICM) of galaxy clusters and radiatively ineffective accretion flows around black holes. We derive the dispersion relation of this instability and obtain the instability condition. There is at least one unstable mode that is independent of the temperature gradient direction for a helical magnetic field geometry. This novel instability is driven by the gyroviscosity coupled with differential rotation. Therefore, we call it gyroviscous-modified magnetorotational instability (GvMRI). We examine how the instability depends on signs of the temperature gradient and the gyroviscosity and also on the magnitude of the thermal frequency and on the values of the pitch angle. We provide a detailed physical interpretation of the obtained results. The GvMRI is applicable not only to the accretion flows and ICM but also to the transition region between cool dense gas and the hot low-density plasma in stellar coronae, accretion disks, and the multiphase interstellar medium because it is independent of the temperature gradient direction.

  3. Susceptibility testing of Propionibacterium acnes comparing agar dilution with E test.

    PubMed Central

    Smith, M A; Alperstein, P; France, K; Vellozzi, E M; Isenberg, H D

    1996-01-01

    Propionibacterium acnes has been identified as a significant agent of nosocomial infections, including endophthalmitis. Data concerning susceptibility of P. acnes to newer beta-lactam antibiotics and fluoroquinolones are limited. Recent reports suggest that quinolones have activity against these organisms sufficient to warrant further study. We undertook a study to select appropriate antimicrobial agents for use in a rabbit model of P. acnes endophthalmitis. We compared the antibiotic susceptibilities of P. acnes by using the National Committee for Clinical Laboratory Standards method of agar dilution with the E test. Thirteen clinical isolates obtained from eye specimens and three American Type Culture Collection control strains were tested against 14 antibiotics. All the clinical isolates were susceptible by both methods to piperacillin, piperacillin-tazobactam, ampicillin-sulbactam, ticarcillin-clavulanate, cefotaxime, cefotetan, ceftriaxone, cefoxitin, and imipenem in addition to clindamycin but were resistant to metronidazole. The clinical P. acnes isolates also displayed high-level susceptibility to ciprofloxacin, sparfloxacin, and ofloxacin. Almost all the P. acnes strains demonstrated E-test MICs within 2 dilutions of the MICs observed by the agar dilution method. Those few strains for which discrepancies were noted exhibited E-test susceptibilities three- to fivefold dilutions lower than the agar dilution method susceptibilities but only with ampicillin-sulbactam, ticarcillin-clavulanate, and/or clindamycin. On the basis of our study, all of clinical eye isolates were susceptible to these newer antimicrobial agents and the two methods demonstrated similar susceptibility patterns. PMID:8815076

  4. Comparison of Culture-Based Methods for Identification of Colonization with Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus in the Context of Cocolonization.

    PubMed

    Davis, Meghan F; Hu, Baofeng; Carroll, Karen C; Bilker, Warren B; Tolomeo, Pam; Cluzet, Valerie C; Baron, Patrick; Ferguson, Jacqueline M; Morris, Daniel O; Rankin, Shelley C; Lautenbach, Ebbing; Nachamkin, Irving

    2016-07-01

    Two screening methods to detect staphylococcal colonization in humans were compared. Direct plating to CHROMagar (BD Diagnostics) was compared to a broth preenrichment followed by plating to Baird-Parker agar. The broth-enrichment method was comparable to CHROMagar for methicillin-resistant Staphylococcus aureas (MRSA) detection, but the enrichment method was optimum for recovery of coagulase-positive Staphylococcus spp. PMID:27122377

  5. Helium 3/Helium 4 dilution cryocooler for space

    NASA Technical Reports Server (NTRS)

    Hendricks, John B.; Dingus, Michael L.

    1991-01-01

    Prototype dilution cryocoolers based on dilution refrigeration and adiabatic demagnetization refrigeration (ADR) cycles were designed, constructed, and tested. Although devices the devices did not operate as fully functional dilution cryocoolers, important information was gathered. The porous metal phase separator was demonstrated to operate in the -1-g configuration; this phase separation is the critical element in the He-3 circulation dilution cryocooler. Improvements in instrumentation needed for additional tests and development were identified.

  6. Assessment of tolerance induction by Origanum vulgare L. essential oil or carvacrol in Pseudomonas aeruginosa cultivated in a meat-based broth and in a meat model.

    PubMed

    da Silva Luz, Isabelle; Gomes-Neto, Nelson Justino; Magnani, Marciane; de Souza, Evandro Leite

    2015-12-01

    This study assessed the efficacy of Origanum vulgare L. essential oil (OVEO) and carvacrol in inhibiting the growth of Pseudomonas aeruginosa ATCC 9027, as well as the development of direct tolerance and cross-tolerance when this bacterium was challenged with sublethal amounts of these substances in a meat-based broth and in a meat model. OVEO and carvacrol at their minimum inhibitory concentrations (MICs), 1/2 MIC and 1/4 MIC decreased the viable cell counts of P. aeruginosa in meat-based broth. Direct tolerance or cross-tolerance was not induced after exposure of the assayed bacterial strain to sublethal amounts of OVEO or carvacrol in meat-based broth and in an artificially contaminated ground beef. Bacterial cells progressively subcultured in meat-based broth with increasing amounts of the tested substances survived up to the MIC of OVEO and to 1/2 MIC of carvacrol. The results reveal a lack of induction of tolerance in P. aeruginosa by exposure to OVEO or carvacrol in meat-based broth and in a meat model. PMID:25293767

  7. 21 CFR 172.710 - Adjuvants for pesticide use dilutions.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Adjuvants for pesticide use dilutions. 172.710... HUMAN CONSUMPTION Other Specific Usage Additives § 172.710 Adjuvants for pesticide use dilutions. The following surfactants and related adjuvants may be safely added to pesticide use dilutions by a grower...

  8. 21 CFR 172.710 - Adjuvants for pesticide use dilutions.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Adjuvants for pesticide use dilutions. 172.710... HUMAN CONSUMPTION Other Specific Usage Additives § 172.710 Adjuvants for pesticide use dilutions. The following surfactants and related adjuvants may be safely added to pesticide use dilutions by a grower...

  9. 21 CFR 172.710 - Adjuvants for pesticide use dilutions.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Adjuvants for pesticide use dilutions. 172.710... Additives § 172.710 Adjuvants for pesticide use dilutions. The following surfactants and related adjuvants may be safely added to pesticide use dilutions by a grower or applicant prior to application to...

  10. 21 CFR 172.710 - Adjuvants for pesticide use dilutions.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Adjuvants for pesticide use dilutions. 172.710... HUMAN CONSUMPTION Other Specific Usage Additives § 172.710 Adjuvants for pesticide use dilutions. The following surfactants and related adjuvants may be safely added to pesticide use dilutions by a grower...

  11. 21 CFR 172.710 - Adjuvants for pesticide use dilutions.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Adjuvants for pesticide use dilutions. 172.710... HUMAN CONSUMPTION Other Specific Usage Additives § 172.710 Adjuvants for pesticide use dilutions. The following surfactants and related adjuvants may be safely added to pesticide use dilutions by a grower...

  12. Flow rate estimation by optical coherence tomography using contrast dilution approach

    NASA Astrophysics Data System (ADS)

    Štohanzlová, Petra; Kolář, Radim

    2015-07-01

    This paper describes experiments and methodology for flow rate estimation using optical coherence tomography and dilution method in single fiber setup. The single fiber is created from custom made glass capillary and polypropylene hollow fiber. As a data source, measurements on single fiber phantom with continuous flow of carrier medium and bolus of Intralipid solution as a contrast agent were used using Thorlabs OCT OCS1300SS. The measured data were processed by methods of image processing, in order to precisely align the individual images in the sequence and extract dilution curves from the area inside the fiber. An experiment proved that optical coherence tomography can be used for flow rate estimation by the dilution method with precision around 7%.

  13. The influence of optimum power level change on boration and dilution operations

    SciTech Connect

    Martinez, A.S.; Andrade Oliveira, E. de . Programa de Engenharia Nuclear.)

    1993-08-01

    Xenon and samarium concentrations changes occur in a nuclear reactor as a consequence of power level variations. To compensate for the reactivity introduced by these isotopes, the boron concentration in the reactor coolant also needs to be changed. Boron concentration changes result from boration or dilution operations. Both boration and dilution operations have economic effects due to the cost of boric acid and the treatment of the effluent. A method is presented that finds the nuclear power level change that leads to an optimization of the boration and dilution operations. The use of the method for practical applications is demonstrated by comparing the absolute reactivity change for the optimum power ramp and a ramp of [plus minus]3%/h. The numerical calculations are very fast. Thus, the method may be implemented in the process computer of any nuclear power plant.

  14. A multiphase model for heterogeneous explosives in both the dense and dilute limits

    SciTech Connect

    Stevens, D E; Murphy, M J; Dunn, T A

    2006-06-26

    Multiphase flow phenomena are important in the characterization of many particle-loaded explosives. A numerical model of these flows must often be capable of accurately simulating both dense and dilute particle loadings and often the transition between the two limits. This presents severe numerical difficulties in that numerical approaches for packed particle beds often behave poorly for the dilute regime and the reverse is often true for methods developed for the dilute regime. This abstract compares two established numerical methods and presents improvements to them. The improved methods have enabled the development of a general purpose model that has been successfully applied to a wide range of problems including the energetic dispersal of solid particles.

  15. Lowering detection limits for 1,2,3-trichloropropane in water using solid phase extraction coupled to purge and trap sample introduction in an isotope dilution GC-MS method.

    PubMed

    Liao, Wenta; Ghabour, Miriam; Draper, William M; Chandrasena, Esala

    2016-09-01

    Purge and trap sample introduction (PTI) has been the premier sampling and preconcentration technique for gas chromatographic determination of volatile organic compounds (VOCs) in drinking water for almost 50 years. PTI affords sub parts-per-billion (ppb) detection limits for purgeable VOCs including fixed gases and higher boiling hydrocarbons and halocarbons. In this study the coupling of solid phase extraction (SPE) to PTI was investigated as a means to substantially increase enrichment and lower detection limits for the emerging contaminant, 1,2,3-trichloropropane (TCP). Water samples (500 mL) were dechlorinated, preserved with a biocide, and spiked with the isotope labeled internal standard, d5-TCP. The entire 500 mL sample was extracted with activated carbon or carbon molecular sieve SPE cartridges, and then eluted with dichloromethane -- excess solvent was removed in a nitrogen evaporator and diethylene glycol "keeper" remaining was dispersed in 5 mL of water for PTI GC-MS analysis. The experimental Method Detection Limit (MDL) for TCP was 0.11 ng/L (ppt) and accuracy was 95-103% in sub-ppt determinations. Groundwater samples including impaired California sources and treated water (n = 21) were analyzed with results ranging from below the method reporting limit (0.30 ng/L) to > 250 ng/L. Coupling of SPE with PTI may provide similar reductions in detection limits for other VOCs with appropriate physical-chemical properties. PMID:27262687

  16. Comparative studies on the activity of basil--an essential oil from Ocimum basilicum L.--against multidrug resistant clinical isolates of the genera Staphylococcus, Enterococcus and Pseudomonas by using different test methods.

    PubMed

    Opalchenova, G; Obreshkova, D

    2003-07-01

    The essential oil basil is obtained from the aerial parts of Ocimum basilicum L. After gas chromatographic separation, the following components were identified: linalol (54.95%), methylchavikol (11.98%), methylcinnamat (7.24%) and linolen (0.14%). The activity of basil against multidrug resistant clinical isolates from the genera Staphylococcus, Enterococcus and Pseudomonas has been studied. For this purpose, standard and modified broth macrodilution methods were used and time kill kinetic of basil was studied. The minimum inhibitory concentrations (MICs) were reported between 0.0030% and 0.0007% (v/v). These concentrations were compared with the inhibitory concentrations (ICs) and the logs of the bacterial counts reduction both obtained by basil diluted in 1% Tween (Tw) 80, saline test solution (STS) and spiritus vini (Sv) 95 degrees instead in a broth. The data, obtained after application of different methods of investigation and validated with membrane filtration, showed a strong inhibitory effect of basil on the test bacteria. The chosen bacteria are widespread and pose serious therapeutic difficulties because of their high level of resistance. For this reason, the results obtained were considered encouraging. PMID:12732427

  17. The Effect of Dilution on the Structure of Microbial Communities

    NASA Technical Reports Server (NTRS)

    Mills, Aaron L.

    2000-01-01

    To determine how dilution of microbial communities affects the diversity of the diluted assemblage a series of numerical simulations were conducted that determined the theoretical change in diversity, richness, and evenness of the community with serial dilution. The results of the simulation suggested that the effects are non linear with a high degree of dependence on the initial evenness of the community being diluted. A series of incubation experiments using a range of dilutions of raw sewage as an inoculum into sterile sewage was used for comparison to the simulations. The diluted communities were maintained in batch fed reactors (three day retention time) for nine days. The communities were harvested and examined by conventional plating and by molecular analysis of the whole-community DNA using AFLP and T-RFLP. Additional, CLPP analysis was also applied. The effects on richness predicted by the numerical simulations were confirmed by the analyses used. The diluted communities fell into three groups, a low dilution, intermediate dilution, and high dilution group, which corresponded well with the groupings obtained for community richness in simulation. The grouping demonstrated the non-linear nature of dilution of whole communities. Furthermore, the results implied that the undiluted community consisted of a few dominant types accompanied by a number of rare (low abundance) types as is typical in unevenly distributed communities.

  18. Diluted magnetic III-V semiconductors

    NASA Astrophysics Data System (ADS)

    Munekata, H.; Ohno, H.; von Molnar, S.; Segmüller, Armin; Chang, L. L.; Esaki, L.

    1989-10-01

    A new diluted magnetic III-V semiconductor of In1-xMnxAs (x<=0.18) has been produced by molecular-beam epitaxy. Films grown at 300 °C are predominantly ferromagnetic and their properties suggest the presence of MnAs clusters. Films grown 200 °C, however, are predominantly paramagnetic, and the lattice constant decreases with increasing Mn composition; both are indicative of the formation of a homogeneous alloy. These films have n-type conductivity and reduced band gaps.

  19. Steadiness in Dilute Pyroclastic Density Currents

    NASA Astrophysics Data System (ADS)

    Andrews, B. J.

    2015-12-01

    Pyroclastic density currents (PDCs) are often unsteady, as evidenced by direct observations of dilute lobes or jets emerging from the fronts of larger currents and by deposits that indicate transient transport and depositional regimes. We used scaled experiments to investigate unsteadiness in dilute PDCs. The experimental currents were run in an 8.5x6.1x2.6 m tank and comprised heated or ambient temperature 20-μm talc powder turbulently suspended in air. Experiments were scaled such that densimetric and thermal Richardson numbers, Froude number, and particle Stokes and settling numbers were dynamically similar to natural dilute PDCs. Although the experiment Reynolds numbers are substantially lower than those of natural PDCs, the experiments are fully turbulent. Experiments were observed with video and high-speed cameras and high-frequency thermocouples. Currents were generated with total eruption durations of 100 s. Unsteadiness in source conditions was produced by interrupting supply for intervals, t, with durations of 1, 2.5, 5, and 10 s in the experimental runs at 35 and 70 s. When t<2.5 s, the currents are indistinguishable from currents with steady supply. In runs with t=2.5-5 s, the individual pulses comprising each current are readily apparent near the source, but decay with distance downstream until the currents appear as single (e.g. steady) flows. In experiments with t=10 s, the 3 pulses comprising each run never merge and the currents remain unsteady. Comparison with the integral turbulent timescale, τ, and current velocity, U, show that unsteadiness is persistent when t>3<τ but currents are steady when t<τ. In currents with 3τ>t>τ, unsteadiness decays such that at a distance of ~4Ut, the currents are again steady. Applied to natural dilute PDCs, our results suggest that currents and their resulting deposits, will only show evidence of unsteadiness if they are disrupted for many seconds and those breaks may "heal" over distances of 100s of meters.

  20. Magnetopolaron effect in diluted semimagnetic semiconductors

    NASA Astrophysics Data System (ADS)

    Tarasov, Georgiy G.; Mazur, Yuri I.; Rakitin, Andrey S.; Lavoric, S. R.; Tomm, Jens W.; Hoerstel, W.

    1997-08-01

    Phonon-assisted self-trapping of free carrier is considered in diluted semimagnetics. It is shown that the binding energy of free magnetic polaron can be substantially larger when the 'spin-phonon' coupling is taken into account. For the particular case of 'soft' lattice dynamics the region of stability for hole-induced polaron can be promoted to the temperature of tenths of degrees and magnetic field of a few Tesla. The possible hybridized excitations with the partition of free magnetic polaron are discussed in semimagnetic semiconductors.

  1. Supershell structure in trapped dilute Fermi gases

    NASA Astrophysics Data System (ADS)

    Yu, Y.; Ögren, M.; Åberg, S.; Reimann, S. M.; Brack, M.

    2005-11-01

    We show that a dilute harmonically trapped two-component gas of fermionic atoms with a weak repulsive interaction has a pronounced super-shell structure: The shell fillings due to the spherical harmonic trapping potential are modulated by a beat mode. This changes the “magic numbers” occurring between the beat nodes by half a period. The length and amplitude of this beating mode depend on the strength of the interaction. We give a simple interpretation of the beat structure in terms of a semiclassical trace formula for the symmetry breaking U(3)→SO(3) .

  2. Supershell structure in trapped dilute Fermi gases

    SciTech Connect

    Yu, Y.; Oegren, M.; Aaberg, S.; Reimann, S. M.; Brack, M.

    2005-11-15

    We show that a dilute harmonically trapped two-component gas of fermionic atoms with a weak repulsive interaction has a pronounced super-shell structure: The shell fillings due to the spherical harmonic trapping potential are modulated by a beat mode. This changes the ''magic numbers'' occurring between the beat nodes by half a period. The length and amplitude of this beating mode depend on the strength of the interaction. We give a simple interpretation of the beat structure in terms of a semiclassical trace formula for the symmetry breaking U(3){yields}SO(3)

  3. Dilution jet mixing program, phase 3

    NASA Technical Reports Server (NTRS)

    Srinivasan, R.; Coleman, E.; Myers, G.; White, C.

    1985-01-01

    The main objectives for the NASA Jet Mixing Phase 3 program were: extension of the data base on the mixing of single sided rows of jets in a confined cross flow to discrete slots, including streamlined, bluff, and angled injections; quantification of the effects of geometrical and flow parameters on penetration and mixing of multiple rows of jets into a confined flow; investigation of in-line, staggered, and dissimilar hole configurations; and development of empirical correlations for predicting temperature distributions for discrete slots and multiple rows of dilution holes.

  4. Purification of nattokinase by reverse micelles extraction from fermentation broth: effect of temperature and phase volume ratio.

    PubMed

    Liu, Jun-Guo; Xing, Jian-Min; Chang, Tian-Shi; Liu, Hui-Zhou

    2006-03-01

    Nattokinase is a novel fibrinolytic enzyme that is considered to be a promising agent for thrombosis therapy. In this study, reverse micelles extraction was applied to purify and concentrate nattokinase from fermentation broth. The effects of temperature and phase volume ratio used for the forward and backward extraction on the extraction process were examined. The optimal temperature for forward and backward extraction were 25 degrees C and 35 degrees C respectively. Nattokinase became more thermosensitive during reverse micelles extraction. And it could be enriched in the stripping phase eight times during backward extraction. It was found that nattokinase could be purified by AOT reverse micelles with up to 80% activity recovery and with a purification factor of 3.9. PMID:16341554

  5. Fabivirga thermotolerans gen. nov., sp. nov., a novel marine bacterium isolated from culture broth of a marine cyanobacterium.

    PubMed

    Tang, M; Chen, C; Li, J; Xiang, W; Wu, H; Wu, J; Dai, S; Wu, H; Li, T; Wang, G

    2016-02-01

    A Gram-stain-negative, red, non-spore-forming, strictly aerobic bacterium, designated strain A4T, was isolated from culture broth of a marine cyanobacterium. Cells were flexible rods with gliding motility. Phylogenetic analysis, based on 16S rRNA gene sequences, revealed that strain A4T formed a coherent cluster with members of the genera Roseivirga and Fabibacter, and represents a distinct lineage in the family Flammeovirgaceae. Thermotolerance and a distinctive cellular fatty acid profile could readily distinguish this isolate from any bacteria of the genera Roseivirga and Fabibacter with a validly published name. On the basis of the phenotypic, chemotaxonomic and phylogenetic characteristics, strain A4T is suggested to represent a novel species in a novel genus, for which the name Fabivirga thermotolerans gen. nov., sp. nov. is proposed. The type strain is A4T ( = KCTC 42507T = CGMCC 1.15111T). PMID:26652750

  6. Assessment of Etest as an alternative to agar dilution for antimicrobial susceptibility testing of Neisseria gonorrhoeae.

    PubMed

    Liu, Hsi; Taylor, Thomas H; Pettus, Kevin; Trees, David

    2014-05-01

    We studied whether the Etest can be used as an alternative to agar dilution to determine antimicrobial susceptibilities of ceftriaxone, cefixime, and cefpodoxime in Neisseria gonorrhoeae surveillance. One hundred fifteen clinical and laboratory isolates of N. gonorrhoeae were tested following the Clinical Laboratory Improvement Amendments (CLIA)-approved CLSI standard agar dilution method and, separately, by the Etest according to the manufacturer's recommendations. The MICs were determined and compared. Ten laboratory-generated mutants were used to simulate substantially nonsusceptible specimens. The Etest and agar dilution methods were well correlated. Statistical tests produced regression R2 values of 88%, 82%, and 85% and Pearson correlation coefficients of 92%, 91%, and 92% for ceftriaxone, cefixime, and cefpodoxime, respectively. When paired comparisons were made, the two tests were 88.7%, 80%, and 87% within 1 log2 dilution from each other for ceftriaxone, cefixime, and cefpodoxime, respectively. The within-2-log2 agreements were 99.1%, 98.3%, and 94.8% for ceftriaxone, cefixime, and cefpodoxime, respectively. Notwithstanding the good correlations and the within-2-log2 general agreement, the Etest results produced slightly lower MICs than the agar dilution results. In conclusion, we found that the Etest can be effectively used as an alternative to agar dilution testing to determine the susceptibility of N. gonorrhoeae to ceftriaxone, cefixime, and cefpodoxime, although we recommend further research into extremely resistant isolates. For isolates within the typical range of clinical MICs, reexamination of the Etest interpretation of susceptible and nonsusceptible categories would likely allow for successful transition from agar dilution to the Etest. PMID:24554750

  7. Assessment of Etest as an Alternative to Agar Dilution for Antimicrobial Susceptibility Testing of Neisseria gonorrhoeae

    PubMed Central

    Taylor, Thomas H.; Pettus, Kevin; Trees, David

    2014-01-01

    We studied whether the Etest can be used as an alternative to agar dilution to determine antimicrobial susceptibilities of ceftriaxone, cefixime, and cefpodoxime in Neisseria gonorrhoeae surveillance. One hundred fifteen clinical and laboratory isolates of N. gonorrhoeae were tested following the Clinical Laboratory Improvement Amendments (CLIA)-approved CLSI standard agar dilution method and, separately, by the Etest according to the manufacturer's recommendations. The MICs were determined and compared. Ten laboratory-generated mutants were used to simulate substantially nonsusceptible specimens. The Etest and agar dilution methods were well correlated. Statistical tests produced regression R2 values of 88%, 82%, and 85% and Pearson correlation coefficients of 92%, 91%, and 92% for ceftriaxone, cefixime, and cefpodoxime, respectively. When paired comparisons were made, the two tests were 88.7%, 80%, and 87% within 1 log2 dilution from each other for ceftriaxone, cefixime, and cefpodoxime, respectively. The within-2-log2 agreements were 99.1%, 98.3%, and 94.8% for ceftriaxone, cefixime, and cefpodoxime, respectively. Notwithstanding the good correlations and the within-2-log2 general agreement, the Etest results produced slightly lower MICs than the agar dilution results. In conclusion, we found that the Etest can be effectively used as an alternative to agar dilution testing to determine the susceptibility of N. gonorrhoeae to ceftriaxone, cefixime, and cefpodoxime, although we recommend further research into extremely resistant isolates. For isolates within the typical range of clinical MICs, reexamination of the Etest interpretation of susceptible and nonsusceptible categories would likely allow for successful transition from agar dilution to the Etest. PMID:24554750

  8. Characterization of and human serologic response to proteins in Helicobacter pylori broth culture supernatants with vacuolizing cytotoxin activity.

    PubMed Central

    Cover, T L; Dooley, C P; Blaser, M J

    1990-01-01

    Helicobacter pylori infection is strongly associated with histologic gastritis and peptic ulcer disease. Broth culture supernatants from a subset of H. pylori strains induce vacuolization in cultured cells, a phenomenon that has been attributed to cytotoxin activity. Concentrated culture supernatants from 15 of 28 (53.6%) H. pylori strains tested induced vacuolization in HeLa cells in titers ranging from 1:10 to 1:180. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining of supernatants from these 28 strains and 2 control strains demonstrated an 82-kilodalton (kDa) protein band in 3 of 16 supernatants with vacuolizing activity, but in none of 14 supernatants without vacuolizing activity. By immunoblotting with human sera, a 128-kDa band was recognized in all 16 supernatants with vacuolizing activity, compared with 9 of 14 (64%) supernatants without vacuolizing activity (P = 0.014). Serologic recognition of the 128-kDa band in H. pylori culture supernatants was more prevalent among persons infected with vacuolizing H. pylori strains than among persons infected with nonvacuolizing strains, but the difference was not statistically significant (80 versus 45%; P = 0.079); human serologic recognition of the 82-kDa band was less common. The 128-kDa band was recognized by 100% of 31 serum samples from H. pylori-infected patients with duodenal ulcer disease, compared with 60.8% of 74 serum samples from H. pylori-infected persons without peptic ulcer disease (P = 0.0001). These data indicate that antigenic 128- and 82-kDa proteins are present in H. pylori broth culture supernatants with vacuolizing activity and that serologic responses to the 128-kDa protein are more prevalent among H. pylori-infected persons with duodenal ulceration than among infected persons without peptic ulceration. Images PMID:2307514

  9. Neutron scattering study of dilute supercritical solutions

    SciTech Connect

    Cochran, H.D.; Wignall, G.D.; Shah, V.M.; Londono, J.D.; Bienkowski, P.R.

    1994-10-01

    Dilute solutions in supercritical solvents exhibit interesting microstructures that are related to their dramatic macroscopic behavior. In typical attractive solutions, solutes are believed to be surrounded by clusters of solvent molecules, and solute molecules are believed to congregate in the vicinity of one another. Repulsive solutions, on the other hand, exhibit a local region of reduced solvent density around the solute with solute-solute congregation. Such microstructures influence solubility, partial molar volume, reaction kinetics, and many other properties. We have undertaken to observe these interesting microstructures directly by neutron scattering experiments on dilute noble gas systems including Ar. The three partial structure factors for such systems and the corresponding pair correlation functions can be determined by using the isotope substitution technique. The systems studied are uniquely suited for our objectives because of the large coherent neutron scattering length of the isotope {sup 36}Ar and because of the accurate potential energy functions that are available for use in molecular simulations and theoretical calculations to be compared with the scattering results. We will describe our experiment, the unique apparatus we have built for it, and the neutron scattering results from our initial allocations of beam time. We will also describe planned scattering experiments to follow those with noble gases, including study of long-chain molecules in supercritical solvents. Such studies will involve hydrocarbon mixtures with and without deuteration to provide contrast.

  10. Diluted equilibrium sterile neutrino dark matter

    NASA Astrophysics Data System (ADS)

    Patwardhan, Amol V.; Fuller, George M.; Kishimoto, Chad T.; Kusenko, Alexander

    2015-11-01

    We present a model where sterile neutrinos with rest masses in the range ˜keV to ˜MeV can be the dark matter and be consistent with all laboratory, cosmological, and large-scale structure, as well as x-ray constraints. These sterile neutrinos are assumed to freeze out of thermal and chemical equilibrium with matter and radiation in the very early Universe, prior to an epoch of prodigious entropy generation ("dilution") from out-of-equilibrium decay of heavy particles. In this work, we consider heavy, entropy-producing particles in the ˜TeV to ˜EeV rest-mass range, possibly associated with new physics at high-energy scales. The process of dilution can give the sterile neutrinos the appropriate relic densities, but it also alters their energy spectra so that they could act like cold dark matter, despite relatively low rest masses as compared to conventional dark matter candidates. Moreover, since the model does not rely on active-sterile mixing for producing the relic density, the mixing angles can be small enough to evade current x-ray or lifetime constraints. Nevertheless, we discuss how future x-ray observations, future lepton number constraints, and future observations and sophisticated simulations of large-scale structure could, in conjunction, provide evidence for this model and/or constrain and probe its parameters.

  11. Stoichiometric controls of mercury dilution by growth.

    PubMed

    Karimi, Roxanne; Chen, Celia Y; Pickhardt, Paul C; Fisher, Nicholas S; Folt, Carol L

    2007-05-01

    Rapid growth could significantly reduce methylmercury (MeHg) concentrations in aquatic organisms by causing a greater than proportional gain in biomass relative to MeHg (somatic growth dilution). We hypothesized that rapid growth from the consumption of high-quality algae, defined by algal nutrient stoichiometry, reduces MeHg concentrations in zooplankton, a major source of MeHg for lake fish. Using a MeHg radiotracer, we measured changes in MeHg concentrations, growth and ingestion rates in juvenile Daphnia pulex fed either high (C:P = 139) or low-quality (C:P = 1317) algae (Ankistrodesmus falcatus) for 5 d. We estimated Daphnia steady-state MeHg concentrations, using a biokinetic model parameterized with experimental rates. Daphnia MeHg assimilation efficiencies (approximately 95%) and release rates (0.04 d(-1)) were unaffected by algal nutrient quality. However, Daphnia growth rate was 3.5 times greater when fed high-quality algae, resulting in pronounced somatic growth dilution. Steady-state MeHg concentrations in Daphnia that consumed high-quality algae were one-third those of Daphnia that consumed low-quality algae due to higher growth and slightly lower ingestion rates. Our findings show that rapid growth from high-quality food consumption can significantly reduce the accumulation and trophic transfer of MeHg in freshwater food webs. PMID:17456601

  12. Stoichiometric controls of mercury dilution by growth

    PubMed Central

    Karimi, Roxanne; Chen, Celia Y.; Pickhardt, Paul C.; Fisher, Nicholas S.; Folt, Carol L.

    2007-01-01

    Rapid growth could significantly reduce methylmercury (MeHg) concentrations in aquatic organisms by causing a greater than proportional gain in biomass relative to MeHg (somatic growth dilution). We hypothesized that rapid growth from the consumption of high-quality algae, defined by algal nutrient stoichiometry, reduces MeHg concentrations in zooplankton, a major source of MeHg for lake fish. Using a MeHg radiotracer, we measured changes in MeHg concentrations, growth and ingestion rates in juvenile Daphnia pulex fed either high (C:P = 139) or low-quality (C:P = 1317) algae (Ankistrodesmus falcatus) for 5 d. We estimated Daphnia steady-state MeHg concentrations, using a biokinetic model parameterized with experimental rates. Daphnia MeHg assimilation efficiencies (≈95%) and release rates (0.04 d−1) were unaffected by algal nutrient quality. However, Daphnia growth rate was 3.5 times greater when fed high-quality algae, resulting in pronounced somatic growth dilution. Steady-state MeHg concentrations in Daphnia that consumed high-quality algae were one-third those of Daphnia that consumed low-quality algae due to higher growth and slightly lower ingestion rates. Our findings show that rapid growth from high-quality food consumption can significantly reduce the accumulation and trophic transfer of MeHg in freshwater food webs. PMID:17456601

  13. A century of indicator dilution technique.

    PubMed

    Henriksen, Jens H; Jensen, Gorm B; Larsson, Henrik B W

    2014-01-01

    This review imparts the history and the present status of the indicator dilution technique with quantitative bolus injection. The first report on flow measurement with this technique appeared 100 years ago. In 1928, the use of intravascular dyes made possible a widespread application in animals and human during the next decades. Multiple indicators, radioactive tracers, inlet-outlet detection and residue detection were introduced in the 1950s and 1960s, and refined along with the development of indicator kinetics. From the 1970s, a wide clinical use in the study of heart, brain, lungs, liver and kidneys developed, and powerful computers in the 1980s and 1990s accorded the technique a new dimension. Today, the indicator dilution technique, on one hand, is applied in the same way as 100 years ago, on the other hand it forms the basis of quantitative SPECT, positron emission tomography, and dynamic MR scans. The technique still undergoes refinement and elaboration as a lasting concept with a high potential for further development. PMID:23869947

  14. Impaired Urine Dilution Capability in HIV Stable Patients

    PubMed Central

    Belloso, Waldo H.; de Paz Sierra, Mariana; Navarro, Matilde; Sanchez, Marisa L.; Perelsztein, Ariel G.; Musso, Carlos G.

    2014-01-01

    Renal disease is a well-recognized complication among patients with HIV infection. Viral infection itself and the use of some antiretroviral drugs contribute to this condition. The thick ascending limb of Henle's loop (TALH) is the tubule segment where free water clearance is generated, determining along with glomerular filtration rate the kidney's ability to dilute urine. Objective. We analyzed the function of the proximal tubule and TALH in patients with HIV infection receiving or not tenofovir-containing antiretroviral treatment in comparison with healthy seronegative controls, by applying a tubular physiological test, hyposaline infusion test (Chaimowitz' test). Material & Methods. Chaimowitz' test was performed on 20 HIV positive volunteers who had normal renal functional parameters. The control group included 10 healthy volunteers. Results. After the test, both HIV groups had a significant reduction of serum sodium and osmolarity compared with the control group. Free water clearance was lower and urine osmolarity was higher in both HIV+ groups. Proximal tubular function was normal in both studied groups. Conclusion. The present study documented that proximal tubule sodium reabsorption was preserved while free water clearance and maximal urine dilution capability were reduced in stable HIV patients treated or not with tenofovir. PMID:24800076

  15. Stable isotope dilution analysis of hydrologic samples by inductively coupled plasma mass spectrometry

    USGS Publications Warehouse

    Garbarino, J.R.; Taylor, H.E.

    1987-01-01

    Inductively coupled plasma mass spectrometry is employed in the determination of Ni, Cu, Sr, Cd, Ba, Ti, and Pb in nonsaline, natural water samples by stable isotope dilution analysis. Hydrologic samples were directly analyzed without any unusual pretreatment. Interference effects related to overlapping isobars, formation of metal oxide and multiply charged ions, and matrix composition were identified and suitable methods of correction evaluated. A comparability study snowed that single-element isotope dilution analysis was only marginally better than sequential multielement isotope dilution analysis. Accuracy and precision of the single-element method were determined on the basis of results obtained for standard reference materials. The instrumental technique was shown to be ideally suited for programs associated with certification of standard reference materials.

  16. Random site dilution properties of frustrated magnets on a hierarchical lattice.

    PubMed

    Fortin, Jean-Yves

    2013-07-24

    We present a method to analyze the magnetic properties of frustrated Ising spin models on specific hierarchical lattices with random dilution. Disorder is induced by dilution and geometrical frustration rather than randomness in the internal couplings of the original Hamiltonian. The two-dimensional model presented here possesses a macroscopic entropy at zero temperature in the large size limit, very close to the Pauling estimate for spin-ice on the pyrochlore lattice, and a crossover towards a paramagnetic phase. The disorder due to dilution is taken into account by considering a replicated version of the recursion equations between partition functions at different lattice sizes. An analysis to first order in replica number allows a systematic reorganization of the disorder configurations, leading to a recurrence scheme. This method is numerically implemented to evaluate thermodynamical quantities such as specific heat and susceptibility in an external field. PMID:23807800

  17. Motor-mediated microtubule self-organization in dilute and semi-dilute filament solutions.

    SciTech Connect

    Swaminathan, S.; Ziebert, F.; Aranson, I. S.; Karpeev, D.

    2011-01-01

    We study molecular motor-induced microtubule self-organization in dilute and semi-dilute filament solutions. In the dilute case, we use a probabilistic model of microtubule interaction via molecular motors to investigate microtubule bundle dynamics. Microtubules are modeled as polar rods interacting through fully inelastic, binary collisions. Our model indicates that initially disordered systems of interacting rods exhibit an orientational instability resulting in spontaneous ordering. We study the existence and dynamic interaction of microtubule bundles analytically and numerically. Our results reveal a long term attraction and coalescing of bundles indicating a clear coarsening in the system; microtubule bundles concentrate into fewer orientations on a slow logarithmic time scale. In semi-dilute filament solutions, multiple motors can bind a filament to several others and, for a critical motor density, induce a transition to an ordered phase with a nonzero mean orientation. Motors attach to a pair of filaments and walk along the pair bringing them into closer alignment. We develop a spatially homogenous, mean-field theory that explicitly accounts for a force-dependent detachment rate of motors, which in turn affects the mean and the fluctuations of the net force acting on a filament. We show that the transition to the oriented state can be both continuous and discontinuous when the force-dependent detachment of motors is important.

  18. Comparative evaluation of antibacterial activity of caffeic acid phenethyl ester and PLGA nanoparticle formulation by different methods.

    PubMed

    Arasoglu, Tülin; Derman, Serap; Mansuroglu, Banu

    2016-01-15

    The aim of the present study was to evaluate the antimicrobial activity of nanoparticle and free formulations of the CAPE compound using different methods and comparing the results in the literature for the first time. In parallel with this purpose, encapsulation of CAPE with the PLGA nanoparticle system (CAPE-PLGA-NPs) and characterization of nanoparticles were carried out. Afterwards, antimicrobial activity of free CAPE and CAPE-PLGA-NPs was determined using agar well diffusion, disk diffusion, broth microdilution and reduction percentage methods. P. aeroginosa, E. coli, S. aureus and methicillin-resistant S. aureus (MRSA) were chosen as model bacteria since they have different cell wall structures. CAPE-PLGA-NPs within the range of 214.0 ± 8.80 nm particle size and with an encapsulation efficiency of 91.59 ± 4.97% were prepared using the oil-in-water (o-w) single-emulsion solvent evaporation method. The microbiological results indicated that free CAPE did not have any antimicrobial activity in any of the applied methods whereas CAPE-PLGA-NPs had significant antimicrobial activity in both broth dilution and reduction percentage methods. CAPE-PLGA-NPs showed moderate antimicrobial activity against S. aureus and MRSA strains particularly in hourly measurements at 30.63 and 61.25 μg ml(-1) concentrations (both p < 0.05), whereas they failed to show antimicrobial activity against Gram-negative bacteria (P. aeroginosa and E. coli, p > 0.05). In the reduction percentage method, in which the highest results of antimicrobial activity were obtained, it was observed that the antimicrobial effect on S. aureus was more long-standing (3 days) and higher in reduction percentage (over 90%). The appearance of antibacterial activity of CAPE-PLGA-NPs may be related to higher penetration into cells due to low solubility of free CAPE in the aqueous medium. Additionally, the biocompatible and biodegradable PLGA nanoparticles could be an alternative to solvents such as ethanol

  19. Comparative evaluation of antibacterial activity of caffeic acid phenethyl ester and PLGA nanoparticle formulation by different methods

    NASA Astrophysics Data System (ADS)

    Arasoglu, Tülin; Derman, Serap; Mansuroglu, Banu

    2016-01-01

    The aim of the present study was to evaluate the antimicrobial activity of nanoparticle and free formulations of the CAPE compound using different methods and comparing the results in the literature for the first time. In parallel with this purpose, encapsulation of CAPE with the PLGA nanoparticle system (CAPE-PLGA-NPs) and characterization of nanoparticles were carried out. Afterwards, antimicrobial activity of free CAPE and CAPE-PLGA-NPs was determined using agar well diffusion, disk diffusion, broth microdilution and reduction percentage methods. P. aeroginosa, E. coli, S. aureus and methicillin-resistant S. aureus (MRSA) were chosen as model bacteria since they have different cell wall structures. CAPE-PLGA-NPs within the range of 214.0 ± 8.80 nm particle size and with an encapsulation efficiency of 91.59 ± 4.97% were prepared using the oil-in-water (o-w) single-emulsion solvent evaporation method. The microbiological results indicated that free CAPE did not have any antimicrobial activity in any of the applied methods whereas CAPE-PLGA-NPs had significant antimicrobial activity in both broth dilution and reduction percentage methods. CAPE-PLGA-NPs showed moderate antimicrobial activity against S. aureus and MRSA strains particularly in hourly measurements at 30.63 and 61.25 μg ml-1 concentrations (both p < 0.05), whereas they failed to show antimicrobial activity against Gram-negative bacteria (P. aeroginosa and E. coli, p > 0.05). In the reduction percentage method, in which the highest results of antimicrobial activity were obtained, it was observed that the antimicrobial effect on S. aureus was more long-standing (3 days) and higher in reduction percentage (over 90%). The appearance of antibacterial activity of CAPE-PLGA-NPs may be related to higher penetration into cells due to low solubility of free CAPE in the aqueous medium. Additionally, the biocompatible and biodegradable PLGA nanoparticles could be an alternative to solvents such as ethanol

  20. Biodiesel Impact on Engine Lubricant Dilution During Active Regeneration of Aftertreatment Systems

    SciTech Connect

    He, X.; Williams, A.; Christensen, E.; Burton, J.; McCormick, R.

    2011-12-01

    Experiments were conducted with ultra low sulfur diesel (ULSD) and 20% biodiesel blends (B20) to compare lube oil dilution levels and lubricant properties for systems using late in-cylinder fuel injection for aftertreatment regeneration. Lube oil dilution was measured by gas chromatography (GC) following ASTM method D3524 to measure diesel content, by Fourier transform infrared (FTIR) spectrometry following a modified ASTM method D7371 to measure biodiesel content, and by a newly developed back-flush GC method that simultaneously measures both diesel and biodiesel. Heavy-duty (HD) engine testing was conducted on a 2008 6.7L Cummins ISB equipped with a diesel oxidation catalyst (DOC) and diesel particle filter (DPF). Stage one of engine testing consisted of 10 consecutive repeats of a forced DPF regeneration event. This continuous operation with late in-cylinder fuel injection served as a method to accelerate lube-oil dilution. Stage two consisted of 16 hours of normal engine operation over a transient test cycle, which created an opportunity for any accumulated fuel in the oil sump to evaporate. Light duty (LD) vehicle testing was conducted on a 2010 VW Jetta equipped with DOC, DPF and a NOx storage catalyst (NSC). Vehicle testing comprised approximately 4,000 miles of operation on a mileage-accumulation dynamometer (MAD) using the U.S. Environmental Protection Agency's Highway Fuel Economy Cycle because of the relatively low engine oil and exhaust temperatures, and high DPF regeneration frequency of this cycle relative to other cycles examined. Comparison of the lube oil dilution analysis methods suggests that D3524 does not measure dilution by biodiesel. The new back-flush GC method provided analysis for both diesel and biodiesel, in a shorter time and with lower detection limit. Thus all lube oil dilution results in this paper are based on this method. Analysis of the HD lube-oil samples showed only 1.5% to 1.6% fuel dilution for both fuels during continuous

  1. Developments on drug discovery and on new therapeutics: highly diluted tinctures act as biological response modifiers

    PubMed Central

    2011-01-01

    Background In the search for new therapies novel drugs and medications are being discovered, developed and tested in laboratories. Highly diluted substances are intended to enhance immune system responses resulting in reduced frequency of various diseases, and often present no risk of serious side-effects due to its low toxicity. Over the past years our research group has been investigating the action of highly diluted substances and tinctures on cells from the immune system. Methods We have developed and tested several highly diluted tinctures and here we describe the biological activity of M1, M2, and M8 both in vitro in immune cells from mice and human, and in vivo in mice. Cytotoxicity, cytokines released and NF-κB activation were determined after in vitro treatment. Cell viability, oxidative response, lipid peroxidation, bone marrow and lymph node cells immunophenotyping were accessed after mice in vivo treatment. Results None of the highly diluted tinctures tested were cytotoxic to macrophages or K562. Lipopolysaccharide (LPS)-stimulated macrophages treated with all highly diluted tinctures decreased tumour necrosis factor alpha (TNF-α) release and M1, and M8 decreased IFN-γ production. M1 has decreased NF-κB activity on TNF-α stimulated reporter cell line. In vivo treatment lead to a decrease in reactive oxygen species (ROS), nitric oxide (NO) production was increased by M1, and M8, and lipid peroxidation was induced by M1, and M2. All compounds enhanced the innate immunity, but M1 also augmented acquired immunity and M2 diminished B lymphocytes, responsible to acquired immunity. Conclusions Based on the results presented here, these highly diluted tinctures were shown to modulate immune responses. Even though further investigation is needed there is an indication that these highly diluted tinctures could be used as therapeutic interventions in disorders where the immune system is compromised. PMID:22029602

  2. Decreasing the Level of Ethyl Acetate in Ethanolic Fermentation Broths of Escherichia coli KO11 by Expression of Pseudomonas putida estZ Esterase†

    PubMed Central

    Hasona, Adnan; York, S. W.; Yomano, L. P.; Ingram, L. O.; Shanmugam, K. T.

    2002-01-01

    During the fermentation of sugars to ethanol relatively high levels of an undesirable coproduct, ethyl acetate, are also produced. With ethanologenic Escherichia coli strain KO11 as the biocatalyst, the level of ethyl acetate in beer containing 4.8% ethanol was 192 mg liter−1. Although the E. coli genome encodes several proteins with esterase activity, neither wild-type strains nor KO11 contained significant ethyl acetate esterase activity. A simple method was developed to rapidly screen bacterial colonies for the presence of esterases which hydrolyze ethyl acetate based on pH change. This method allowed identification of Pseudomonas putida NRRL B-18435 as a source of this activity and the cloning of a new esterase gene, estZ. Recombinant EstZ esterase was purified to near homogeneity and characterized. It belongs to family IV of lipolytic enzymes and contains the conserved catalytic triad of serine, aspartic acid, and histidine. As expected, this serine esterase was inhibited by phenylmethylsulfonyl fluoride and the histidine reagent diethylpyrocarbonate. The native and subunit molecular weights of the recombinant protein were 36,000, indicating that the enzyme exists as a monomer. By using α-naphthyl acetate as a model substrate, optimal activity was observed at pH 7.5 and 40°C. The Km and Vmax for α-naphthyl acetate were 18 μM and 48.1 μmol · min−1 · mg of protein−1, respectively. Among the aliphatic esters tested, the highest activity was obtained with propyl acetate (96 μmol · min−1 · mg of protein−1), followed by ethyl acetate (66 μmol · min−1 · mg of protein−1). Expression of estZ in E. coli KO11 reduced the concentration of ethyl acetate in fermentation broth (4.8% ethanol) to less than 20 mg liter−1. PMID:12039716

  3. Growth Kinetics of Listeria monocytogenes in Broth and Beef Frankfurters– Determination of Lag Phase Duration and Exponential Growth Rate under Isothermal Conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this research was to develop a new kinetic model to describe the isothermal growth of microorganisms. The new model was tested with Listeria monocytogenes in broth and frankfurters, and compared with two commonly used models - Baranyi and modified Gompertz models. Bias factor (BF)...

  4. Suppression of pecan and peach pathogens using metabolites or broths of from symbiotic bacteria obtained from the guts of entomopathogenic nematodes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Concentrated metabolites from the bacteria Xenorhabdus spp. and Photorhabdus spp. have previously been shown to suppress growth of peach and pecan pathogens in vitro, and reduce disease on detached leaves or terminals. The objectives of this study were 1) determine if bacterial broths (in addition t...

  5. Disorder Problem In Diluted Magnetic Semiconductors

    NASA Astrophysics Data System (ADS)

    Nelson, Ryky; Ekuma, Chinedu; Terletska, Hanna; Sudhindra, Vidhyadhiraja; Moreno, Juana; Jarrell, Mark

    2015-03-01

    Motivated by experimental studies addressing the role of impurity disorder in diluted magnetic semiconductors (DMS), we investigate the effects of disorder using a simple tight-binding Hamiltonian with random impurity potential and spin-fermion exchange which is self-consistently solved using the typical medium theory. Adopting the typical density of states (TDoS) as the order parameter, we find that the TDoS vanishes below a critical concentration of the impurity, which indicates an Anderson localization transition in the system. Our results qualitatively explain why at concentrations lower than a critical value DMS are insulating and paramagnetic, while at larger concentrations are ferromagnetic. We also compare several simple models to explore the interplay between ferromagnetic order and disorder induced insulating behavior, and the role of the spin-orbit interaction on this competition. We apply our findings to (Ga,Mn)As and (Ga,Mn)N to compare and contrast their phase diagrams.

  6. Crystallization of a dilute atomic dipolar condensate

    NASA Astrophysics Data System (ADS)

    Bisset, Russell; Blakie, Blair

    2016-05-01

    A recent experiment found that a dilute BEC of highly-magnetic dysprosium atoms may spontaneously break up into a crystal of droplets, a process reminiscent of the Rosensweig instability [ArXiv:1508.05007]. We dynamically simulate this scenario and find that the standard dipolar Gross-Pitaevskii equation (GPE) cannot explain such a droplet crystal. Indeed, the GPE predicts too much heating during the violent droplet formation, and a droplet lifetime that is much shorter than observed in the experiment. We investigate the requisite properties of the unknown stabilization mechanism, and find that an effective repulsive interaction with a higher order density dependence than the usual two-body interactions is required to quantitatively reproduce the experimental results.

  7. Dilution Jet Mixing Program, phase 1

    NASA Technical Reports Server (NTRS)

    Srinivasan, R.; Berenfeld, A.; Mongia, H. C.

    1982-01-01

    The effect of jet to mainstream density ratio, flow area convergence as encounted in transition sections, and nonuniform mainstream profile upstream of dilution orifices on the mixing of a row of jets with a confined cross flow was quantified. It is found that: (1) jet spreading rate in transverse direction is increased with increasing J, H/D and with decreasing S/D; (2) the density ratio has only a second order effect on the jet mixing characteristics for a constant momentum ratio; (3) the temperature distributions in the jet mixing region are strongly influenced by the undisturbed mainstream profile; (4) flow area convergence enhances mixing in radial and transverse directions. An asymmetric convergent duct with flat wall injection has the same jet mixing characteristics as a symmetric convergent duct. An asymmetric convergent duct with slant wall injection has a faster jet spreading rate in the transverse direction.

  8. Computational modeling of dilute biomass slurries

    NASA Astrophysics Data System (ADS)

    Sprague, Michael; Stickel, Jonathan; Fischer, Paul; Lischeske, James

    2012-11-01

    The biochemical conversion of lignocellulosic biomass to liquid transportation fuels involves a multitude of physical and chemical transformations that occur in several distinct processing steps (e.g., pretreatment, enzymatic hydrolysis, and fermentation). In this work we focus on development of a computational fluid dynamics model of a dilute biomass slurry, which is a highly viscous particle-laden fluid that can exhibit yield-stress behavior. Here, we model the biomass slurry as a generalized Newtonian fluid that accommodates biomass transport due to settling and biomass-concentration-dependent viscosity. Within a typical mixing vessel, viscosity can vary over several orders of magnitude. We solve the model with the Nek5000 spectral-finite-element solver in a simple vane mixer, and validate against experimental results. This work is directed towards our goal of a fully coupled computational model of fluid dynamics and reaction kinetics for the enzymatic hydrolysis of lignocellulosic biomass.

  9. Negative magnetophoresis in diluted ferrofluid flow.

    PubMed

    Hejazian, Majid; Nguyen, Nam-Trung

    2015-07-21

    We report magnetic manipulation of non-magnetic particles suspended in diluted ferrofluid. Diamagnetic particles were introduced into a circular chamber to study the extent of their deflection under the effect of a non-uniform magnetic field of a permanent magnet. Since ferrofluid is a paramagnetic medium, it also experiences a bulk magnetic force that in turn induces a secondary flow opposing the main hydrodynamic flow. Sheath flow rate, particle size, and magnetic field strength were varied to examine this complex behaviour. The combined effect of negative magnetophoresis and magnetically induced secondary flow leads to various operation regimes, which can potentially find applications in separation, trapping and mixing of diamagnetic particles such as cells in a microfluidic system. PMID:26054840

  10. Dynamical Threshold of Diluteness of Soft Colloids

    SciTech Connect

    Chen, Wei-Ren; Do, Changwoo; Egami, T; Falus, Peter; Li, Xin; Liu, Dazhi; Porcar, L.; Sanchez-Diaz, Luis E; Smith, Gregory Scott; Wu, Bin

    2014-01-01

    The dynamics of soft colloids in solutions is characterized by internal collective motion as well as center-of-mass diffusion. Using neutron scattering we demonstrate that the competition between the relaxation processes associated with these two degrees of freedom results in strong dependence of dynamics and structure on colloid concentration, c, well below the overlap concentration c*. Triggered by the increasing inter-particle collisions, substantial structural dehydration and slowing-down of internal dynamics occurs before geometrically defined colloidal overlap develops. This observation is surprising since it is generally believed that the internal dynamics and conformation of soft colloidal particles essentially remain invariant below c*. The competition between these two relaxation processes gives rise to a new dynamically-defined dilute threshold concentration well below c*.

  11. Sibling dilution hypothesis: a regression surface analysis.

    PubMed

    Marjoribanks, K

    2001-08-01

    This study examined relationships between sibship size (the number of children in a family), birth order, and measures of academic performance, academic self-concept, and educational aspirations at different levels of family educational resources. As part of a national longitudinal study of Australian secondary school students data were collected from 2,530 boys and 2,450 girls in Years 9 and 10. Regression surfaces were constructed from models that included terms to account for linear, interaction, and curvilinear associations among the variables. Analysis suggests the general propositions (a) family educational resources have significant associations with children's school-related outcomes at different levels of sibling variables, the relationships for girls being curvilinear, and (b) sibling variables continue to have small significant associations with affective and cognitive outcomes, after taking into account variations in family educational resources. That is, the investigation provides only partial support for the sibling dilution hypothesis. PMID:11729548

  12. Dilute acid saccharification of lignocellulosic biomass

    SciTech Connect

    Penner, M.H.; Hashimoto, A.G.

    1995-12-01

    Aqueous dilute sulfuric acid solutions have been evaluated in terms of their effectiveness for the saccharification of the insoluble xylan fraction of poplar and switchgrass feedstocks. Acid concentrations ranging from .6 to 1.2% have been tested at temperatures ranging from 120 to 160{degrees}C. Treatments at optimum time, temperature, and acid combinations provided xylose yields of approximately 90% theoretical. Rate constants associated with xylan hydrolysis and xylose degradation for each of the feed-stocks have been evaluated. In general, optimum yields were associated with high temperature treatments for relatively short reaction times. Results from our laboratory will be presented with reference to previously published studies on hemicellulose saccharification and in the general context of converting lignocellulosic biomass to useful products.

  13. Dilute spin-orbit Fermi gases

    NASA Astrophysics Data System (ADS)

    Maldonado-Mundo, Daniel; He, Lianyi; Öhberg, Patrik; Valiente, Manuel

    2014-03-01

    We study repulsive Fermi gases with Rashba spin-orbit coupling in two and three dimensions when they are dilute enough that a single branch of the spectrum is occupied in the non-interacting ground state. We develop an effective renormalizable theory for fermions in the lower branch and obtain the energy of the system in three dimensions to second order in the renormalized coupling constant. We then exploit the non-Galilean-relativistic nature of spin-orbit coupled gases. We find that at finite momentum, the two-dimensional Fermi sea is deformed in a non-trivial way. Using mean-field theory to include interactions, we show that the ground-state of the system acquires a finite momentum, and is consequently deformed, when the interaction is stronger than a critical value. Heriot-Watt University. CM-DTC. SUPA. EPSRC.

  14. Diluted neural network with refractory periods

    NASA Astrophysics Data System (ADS)

    da Silva, Crisógono R.; Tamarit, Francisco A.; Curado, Evaldo M. F.

    1997-03-01

    We study an extreme and asymmetrically diluted version of the Hopfield model when the refractory period is taken into account in the dynamics of the neurons through a time dependent threshold. We present an analytical approach that allows one to preserve, in an approximate way, the dependence of the system on its whole history. In particular, we obtain a recurrent equation for the overlap from which one can analyze the retrieval capacity. We also perform numerical simulations that are well fitted by our analytical results. Depending on the amplitude of the potential that mimics the effect of the refractory period and on the ratio α between the number of stored patterns p and the mean connectivity per neuron C, the system presents different dynamical behaviors and retrieval abilities.

  15. Postoperative bypass bleeding: a bypass-associated dilutional (BAD) coagulopathy?

    PubMed

    Bull, Brian S; Hay, Karen L; Herrmann, Paul C

    2009-01-01

    A number of associations with post-bypass bleeding have been described in the accompanying paper. Herein we hypothesize that dilution is an underlying cause through a malign series of bypass-associated events. Heparinized blood behaves anomalously when diluted. Clotting times first shorten somewhat, then--as the dilution of whole blood approaches 50%--rapidly lengthen to unclottability. During cardiopulmonary bypass, low blood volume patients are at a significant risk of clotting factor dilution which will always be more severe than the level of whole blood dilution. If severe enough, this dilution may lower plasma clotting factors to a critical level and may result in excess protamine administration, secondary to overestimation of heparin. The presence of un-neutralized protamine combined with critically lowered clotting factors leads to marked coagulopathy. PMID:19699663

  16. Dilute Oxygen Combustion Phase 3 Final Report

    SciTech Connect

    Riley, M.F.; Ryan, H.M.

    2000-05-31

    Dilute Oxygen Combustion (DOC) burners have been successfully installed and operated in the reheat furnace at Auburn Steel Co., Inc., Auburn, NY, under Phase 3 of the Dilute Oxygen Combustion project. Two new preheat zones were created employing a total of eight 6.5 MMBtu/hr capacity burners. The preheat zones provide a 30 percent increase in maximum furnace production rate, from 75 tph to 100 tph. The fuel rate is essentially unchanged, with the fuel savings expected from oxy-fuel combustion being offset by higher flue gas temperatures. When allowance is made for the high nitrogen level and high gas phase temperature in the furnace, measured NOx emissions are in line with laboratory data on DOC burners developed in Phase 1 of the project. Burner performance has been good and there have been no operating or maintenance problems. The DOC system continues to be used as part of Auburn Steel?s standard reheat furnace practice. High gas phase temperature is a result of the high firing density needed to achieve high production rates, and little opportunity exists for improvement in that area. However, fuel and NOx performance can be improved by further conversion of furnace zones to DOC burners, which will lower furnace nitrogen levels. Major obstacles are cost and concern about increased formation of oxide scale on the steel. Oxide scale formation may be enhanced by exposure of the steel to higher concentrations of oxidizing gas components (primarily products of combustion) in the higher temperature zones of the furnace. Phase 4 of the DOC project will examine the rate of oxide scale formation in these higher temperature zones and develop countermeasures that will allow DOC burners to be used successfully in these furnace zones.

  17. Dilute Oxygen Combustion - Phase 3 Report

    SciTech Connect

    Riley, Michael F.

    2000-05-31

    Dilute Oxygen Combustion (DOC) burners have been successfully installed and operated in the reheat furnace at Auburn Steel Co., Inc., Auburn, NY, under Phase 3 of the Dilute Oxygen Combustion project. Two new preheat zones were created employing a total of eight 6.5 MMBtu/hr capacity burners. The preheat zones provide a 30 percent increase in maximum furnace production rate, from 75 tph to 100 tph. The fuel rate is essentially unchanged, with the fuel savings expected from oxy-fuel combustion being offset by higher flue gas temperatures. When allowance is made for the high nitrogen level and high gas phase temperature in the furnace, measured NOx emissions are in line with laboratory data on DOC burners developed in Phase 1 of the project. Burner performance has been good, and there have been no operating or maintenance problems. The DOC system continues to be used as part of Auburn Steel's standard reheat furnace practice. High gas phase temperature is a result of the high firing density needed to achieve high production rates, and little opportunity exists for improvement in that area. However, fuel and NOx performance can be improved by further conversion on furnace zones to DOC burners, which will lower furnace nitrogen levels. Major obstacles are cost and concern about increased formation of oxide scale on the steel. Oxide scale formation may be enhanced by exposure of the steel to higher concentrations of oxidizing gas components (primarily products of combustion) in the higher temperature zones of the furnace. Phase 4 of the DOC project will examine the rate of oxide scale formation in these higher temperature zones and develop countermeasures that will allow DOC burners to be used successfully in these furnace zones.

  18. HIV and concurrent sexual partnerships: modelling the role of coital dilution

    PubMed Central

    2011-01-01

    Background The concurrency hypothesis asserts that high prevalence of overlapping sexual partnerships explains extraordinarily high HIV levels in sub-Saharan Africa. Earlier simulation models show that the network effect of concurrency can increase HIV incidence, but those models do not account for the coital dilution effect (non-primary partnerships have lower coital frequency than primary partnerships). Methods We modify the model of Eaton et al (AIDS and Behavior, September 2010) to incorporate coital dilution by assigning lower coital frequencies to non-primary partnerships. We parameterize coital dilution based on the empirical work of Morris et al (PLoS ONE, December 2010) and others. Following Eaton et al, we simulate the daily transmission of HIV over 250 years for 10 levels of concurrency. Results At every level of concurrency, our focal coital-dilution simulation produces epidemic extinction. Our sensitivity analysis shows that this result is quite robust; even modestly lower coital frequencies in non-primary partnerships lead to epidemic extinction. Conclusions In order to contribute usefully to the investigation of HIV prevalence, simulation models of concurrent partnering and HIV epidemics must incorporate realistic degrees of coital dilution. Doing so dramatically reduces the role that concurrency can play in accelerating the spread of HIV and suggests that concurrency cannot be an important driver of HIV epidemics in sub-Saharan Africa. Alternative explanations for HIV epidemics in sub-Saharan Africa are needed. PMID:21914208

  19. Dry Blending to Achieve Isotopic Dilution of Highly Enriched Uranium Oxide Materials

    SciTech Connect

    Henry, Roger Neil; Chipman, Nathan Alan; Rajamani, R. K.

    2001-04-01

    The end of the cold war produced large amounts of excess fissile materials in the United States and Russia. The Department of Energy has initiated numerous activities to focus on identifying material management strategies for disposition of these excess materials. To date, many of these planning strategies have included isotopic dilution of highly enriched uranium as a means of reducing the proliferation and safety risks. Isotopic dilution by dry blending highly enriched uranium with natural and/or depleted uranium has been identified as one non-aqueous method to achieve these risk (proliferation and criticality safety) reductions. This paper reviews the technology of dry blending as applied to free flowing oxide materials.

  20. Identification of Gram-Negative Bacteria and Genetic Resistance Determinants from Positive Blood Culture Broths by Use of the Verigene Gram-Negative Blood Culture Multiplex Microarray-Based Molecular Assay

    PubMed Central

    Ledeboer, Nathan A.; Lopansri, Bert K.; Dhiman, Neelam; Cavagnolo, Robert; Carroll, Karen C.; Granato, Paul; Thomson, Richard; Butler-Wu, Susan M.; Berger, Heather; Samuel, Linoj; Pancholi, Preeti; Swyers, Lettie; Hansen, Glen T.; Tran, Nam K.; Polage, Christopher R.; Thomson, Kenneth S.; Hanson, Nancy D.; Winegar, Richard

    2015-01-01

    Bloodstream infection is a serious condition associated with significant morbidity and mortality. The outcome of these infections can be positively affected by the early implementation of effective antibiotic therapy based on the identification of the infecting organism and genetic markers associated with antibiotic resistance. In this study, we evaluated the microarray-based Verigene Gram-negative blood culture (BC-GN) assay in the identification of 8 genus or species targets and 6 genetic resistance determinants in positive blood culture broths. A total of 1,847 blood cultures containing Gram-negative organisms were tested using the BC-GN assay. This comprised 729 prospective fresh, 781 prospective or retrospective frozen, and 337 simulated cultures representing 7 types of aerobic culture media. The results were compared to those with standard bacterial culture and biochemical identification with nucleic acid sequence confirmation of the resistance determinants. Among monomicrobial cultures, the positive percent agreement (PPA) of the BC-GN assay with the reference method was as follows; Escherichia coli, 100%; Klebsiella pneumoniae, 92.9%; Klebsiella oxytoca, 95.5%; Enterobacter spp., 99.3%; Pseudomonas aeruginosa, 98.9%; Proteus spp., 100%; Acinetobacter spp., 98.4%; and Citrobacter spp., 100%. All organism identification targets demonstrated >99.5% negative percent agreement (NPA) with the reference method. Of note, 25/26 cultures containing K. pneumoniae that were reported as not detected by the BC-GN assay were subsequently identified as Klebsiella variicola. The PPA for identification of resistance determinants was as follows; blaCTX-M, 98.9%; blaKPC, 100%; blaNDM, 96.2%; blaOXA, 94.3%; blaVIM, 100%; and blaIMP, 100%. All resistance determinant targets demonstrated >99.9% NPA. Among polymicrobial specimens, the BC-GN assay correctly identified at least one organism in 95.4% of the broths and correctly identified all organisms present in 54.5% of the broths

  1. Identification of Gram-Negative Bacteria and Genetic Resistance Determinants from Positive Blood Culture Broths by Use of the Verigene Gram-Negative Blood Culture Multiplex Microarray-Based Molecular Assay.

    PubMed

    Ledeboer, Nathan A; Lopansri, Bert K; Dhiman, Neelam; Cavagnolo, Robert; Carroll, Karen C; Granato, Paul; Thomson, Richard; Butler-Wu, Susan M; Berger, Heather; Samuel, Linoj; Pancholi, Preeti; Swyers, Lettie; Hansen, Glen T; Tran, Nam K; Polage, Christopher R; Thomson, Kenneth S; Hanson, Nancy D; Winegar, Richard; Buchan, Blake W

    2015-08-01

    Bloodstream infection is a serious condition associated with significant morbidity and mortality. The outcome of these infections can be positively affected by the early implementation of effective antibiotic therapy based on the identification of the infecting organism and genetic markers associated with antibiotic resistance. In this study, we evaluated the microarray-based Verigene Gram-negative blood culture (BC-GN) assay in the identification of 8 genus or species targets and 6 genetic resistance determinants in positive blood culture broths. A total of 1,847 blood cultures containing Gram-negative organisms were tested using the BC-GN assay. This comprised 729 prospective fresh, 781 prospective or retrospective frozen, and 337 simulated cultures representing 7 types of aerobic culture media. The results were compared to those with standard bacterial culture and biochemical identification with nucleic acid sequence confirmation of the resistance determinants. Among monomicrobial cultures, the positive percent agreement (PPA) of the BC-GN assay with the reference method was as follows; Escherichia coli, 100%; Klebsiella pneumoniae, 92.9%; Klebsiella oxytoca, 95.5%; Enterobacter spp., 99.3%; Pseudomonas aeruginosa, 98.9%; Proteus spp., 100%; Acinetobacter spp., 98.4%; and Citrobacter spp., 100%. All organism identification targets demonstrated >99.5% negative percent agreement (NPA) with the reference method. Of note, 25/26 cultures containing K. pneumoniae that were reported as not detected by the BC-GN assay were subsequently identified as Klebsiella variicola. The PPA for identification of resistance determinants was as follows; blaCTX-M, 98.9%; blaKPC, 100%; blaNDM, 96.2%; blaOXA, 94.3%; blaVIM, 100%; and blaIMP, 100%. All resistance determinant targets demonstrated >99.9% NPA. Among polymicrobial specimens, the BC-GN assay correctly identified at least one organism in 95.4% of the broths and correctly identified all organisms present in 54.5% of the broths

  2. Evaluation of the Xpert vanA/vanB Assay Using Enriched Inoculated Broths for Direct Detection of vanB Vancomycin-Resistant Enterococci

    PubMed Central

    Arends, J. P.; Kampinga, G. A.; Ahmad, H. M.; Dijkhuizen, B.; van Barneveld, P.; Rossen, J. W. A.; Friedrich, A. W.

    2014-01-01

    Rapid and accurate detection of VRE (vancomycin-resistant enterococci) is required for adequate antimicrobial treatment and infection prevention measures. Previous studies using PCR for the detection of VRE, including Cepheid's Xpert vanA/vanB assay, reported accurate detection of vanA VRE; however, many false-positive results were found for vanB VRE. This is mainly due to nonenterococcal vanB genes, which can be found in the gut flora. Our goal was to optimize the rapid and accurate detection of vanB VRE and to improve the positive predictive value (PPV) by limiting false-positive results. We evaluated the use of the Xpert vanA/vanB assay on rectal swabs and on enriched inoculated broths for the detection of vanB VRE. By adjusting the cycle threshold (CT) cutoff value to ≤25 for positivity by PCR on enriched broths, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 96.9%, 100%, 100%, and 99.5% for vanB VRE, respectively. As shown in this study, CT values of ≤25 acquired from enriched broths can be considered true positive. For broths with CT values between 25 and 30, we recommend confirming the results by culture. CT values of >30 appeared to be true negative. In conclusion, this study shows that the Cepheid's Xpert vanA/vanB assay performed on enriched inoculated broths with an adjusted cutoff CT value is a useful and rapid tool for the detection of vanB VRE. PMID:25297325

  3. Characterization of dilution action in laser-induction hybrid cladding

    NASA Astrophysics Data System (ADS)

    Huang, Yongjun

    2011-07-01

    Based on an experimental study of laser-induction hybrid cladding by powder feeding, the dilution action and elemental composition distribution were investigated in detail. The results indicate that, compared with individual laser cladding, by using laser-induction hybrid cladding it is easier to form a metallurgical bonding coating and the change range of dilution is much larger. Moreover, at the bottom of molten region, the morphology exhibits nearly a straight line. The processing parameters have great influence on dilution in hybrid cladding. With the increase of scanning speed, the tendency of dilution presents a U-shaped profile, i.e., the middle dilution is much less than those of two ends. The dilution increases with the induction energy. Furthermore, the bigger the dilution, the more uniform is the elemental composition throughout coating. In laser-induction hybrid cladding, the microstructure of low dilution coating is relatively fine due to the low hybrid cladding energy. By adjusting the laser energy and induction energy appropriately, i.e., high induction energy—low laser energy, the low dilution coating with fine microstructure and good mechanical properties can be achieved.

  4. High-throughput ab-initio dilute solute diffusion database

    PubMed Central

    Wu, Henry; Mayeshiba, Tam; Morgan, Dane

    2016-01-01

    We demonstrate automated generation of diffusion databases from high-throughput density functional theory (DFT) calculations. A total of more than 230 dilute solute diffusion systems in Mg, Al, Cu, Ni, Pd, and Pt host lattices have been determined using multi-frequency diffusion models. We apply a correction method for solute diffusion in alloys using experimental and simulated values of host self-diffusivity. We find good agreement with experimental solute diffusion data, obtaining a weighted activation barrier RMS error of 0.176 eV when excluding magnetic solutes in non-magnetic alloys. The compiled database is the largest collection of consistently calculated ab-initio solute diffusion data in the world. PMID:27434308

  5. Degradation of Sodium-Polyacrylate in Dilute Aqueous Solution, II

    NASA Astrophysics Data System (ADS)

    Saita, Takao; Matumura, On

    1983-08-01

    It has been found that Na-PAA molecules in dilute aqueous solution are degraded by shearing stress, oxidation and photolysis during usual viscosity measurements with a capillary viscometer. The results of previous viscosity measurements, mainly about the mechanochemical degradation in air and in air-free conditions, showed that the degradation rate increases with increasing shear stress, and with decreasing polymer concentration. In this work, the effects of the molecular weight and temperature on the degradation rate are measured using a capillary viscometer in air, and the photodegradation of Na-PAA and PAA in aqueous solution irradiated with UV light are studied by viscosity measurements in air, and by UV absorption and ESR methods. The results show that the degradation of molecules is enhanced by an increase in the molecular weight and strongly accelerated by a rise in temperature and by UV irradiation, and is accompanied by free-radical chain reactions.

  6. High-throughput ab-initio dilute solute diffusion database.

    PubMed

    Wu, Henry; Mayeshiba, Tam; Morgan, Dane

    2016-01-01

    We demonstrate automated generation of diffusion databases from high-throughput density functional theory (DFT) calculations. A total of more than 230 dilute solute diffusion systems in Mg, Al, Cu, Ni, Pd, and Pt host lattices have been determined using multi-frequency diffusion models. We apply a correction method for solute diffusion in alloys using experimental and simulated values of host self-diffusivity. We find good agreement with experimental solute diffusion data, obtaining a weighted activation barrier RMS error of 0.176 eV when excluding magnetic solutes in non-magnetic alloys. The compiled database is the largest collection of consistently calculated ab-initio solute diffusion data in the world. PMID:27434308

  7. Validation of a nanoliquid chromatography-tandem mass spectrometry method for the identification and the accurate quantification by isotopic dilution of glutathionylated and cysteinylated precursors of 3-mercaptohexan-1-ol and 4-mercapto-4-methylpentan-2-one in white grape juices.

    PubMed

    Roland, Aurélie; Vialaret, Jérôme; Moniatte, Marc; Rigou, Peggy; Razungles, Alain; Schneider, Rémi

    2010-03-01

    A rapid nanoLC-MS/MS method was developed and validated for the simultaneous determination of glutathionylated and cysteinylated precursors of 3-mercapto-hexan-1-ol (3MH) and 4-methyl-4-mercaptopentan-2-one in grape juice using stable isotope dilution assay (SIDA). The analytes were extracted from must using a cation exchange resin and purified on C18 cartridges. They were chromatographically separated on a reverse phase column and finally analyzed by tandem mass spectrometry in selected reaction monitoring mode (SRM) using deuterated analogues as standards except for glutathionylated conjugate of 4MMP which was analyzed by external calibration. The method was validated according to the International Conference on Harmonization recommendations by determining linearity, accuracy, precision, recovery, matrix effect, repeatability, intermediate reproducibility, LODs and LOQs. Calibration for each precursor was determined by performing Lack-of-Fit test and the best fitting for 3MH precursors was a quadratic model whereas a linear model was better adapted for 4MMP precursors. All calibration curves showed quite satisfactory correlation coefficients (R(2)>0.995 for SIDA quantification and R(2)>0.985 for external calibration). Quantification by SIDA and external calibration allowed a high level of accuracy since the averaged value ranged from 80 to 108%. Quantification of aroma precursors was accurate and reproducible over five days since intermediate precision (same analyst, same sample and same apparatus), which was evaluated by the calculation of RSD was inferior to 16%. Limits of quantification for G3MH and G4MMP were closed to 0.50 and 0.07 nmol/L and as 4.75 and 1.90 nmol/L for Cys3MH and Cys4MMP respectively. This method was applied to the quantification of precursors into several types of grape juices: Melon B., Sauvignon, Riesling and Gewurztraminer. PMID:20122692

  8. Comparison of bile acid synthesis determined by isotope dilution versus fecal acidic sterol output in human subjects

    SciTech Connect

    Duane, W.C.; Holloway, D.E.; Hutton, S.W.; Corcoran, P.J.; Haas, N.A.

    1982-05-01

    Fecal acidic sterol output has been found to be much lower than bile acid synthesis determined by isotope dilution. Because of this confusing discrepancy, we compared these 2 measurements done simultaneously on 13 occasions in 5 normal volunteers. In contrast to previous findings, bile acid synthesis by the Lindstedt isotope dilution method averaged 16.3% lower than synthesis simultaneously determined by fecal acidic sterol output (95% confidence limit for the difference - 22.2 to -10.4%). When one-sample determinations of bile acid pools were substituted for Lindstedt pools, bile acid synthesis by isotope dilution averaged 5.6% higher than synthesis by fecal acidic sterol output (95% confidence limits -4.9 to 16.1%). These data indicate that the 2 methods yield values in reasonably close agreement with one another. If anything, fecal acidic sterol outputs are slightly higher than synthesis by isotope dilution.

  9. Comparative Study of SPORL and Dilute Acid Pretreatments of Spruce for Cellulosic Ethanol Production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The performance of two pretreatment methods, Sulfite Pretreatment to Overcome Recalcitrance of Lignocellulose (SPORL) and Dilute Acid (DA), was compared in pretreating softwood (spruce) for fuel ethanol production under the same conditions of temperature (180°C), time (30 min), sulfuric acid loading...

  10. An Isotopic Dilution Experiment Using Liquid Scintillation: A Simple Two-System, Two-Phase Analysis.

    ERIC Educational Resources Information Center

    Moehs, Peter J.; Levine, Samuel

    1982-01-01

    A simple isotonic, dilution analysis whose principles apply to methods of more complex radioanalyses is described. Suitable for clinical and instrumental analysis chemistry students, experimental manipulations are kept to a minimum involving only aqueous extraction before counting. Background information, procedures, and results are discussed.…

  11. Weighted Geometric Dilution of Precision Calculations with Matrix Multiplication

    PubMed Central

    Chen, Chien-Sheng

    2015-01-01

    To enhance the performance of location estimation in wireless positioning systems, the geometric dilution of precision (GDOP) is widely used as a criterion for selecting measurement units. Since GDOP represents the geometric effect on the relationship between measurement error and positioning determination error, the smallest GDOP of the measurement unit subset is usually chosen for positioning. The conventional GDOP calculation using matrix inversion method requires many operations. Because more and more measurement units can be chosen nowadays, an efficient calculation should be designed to decrease the complexity. Since the performance of each measurement unit is different, the weighted GDOP (WGDOP), instead of GDOP, is used to select the measurement units to improve the accuracy of location. To calculate WGDOP effectively and efficiently, the closed-form solution for WGDOP calculation is proposed when more than four measurements are available. In this paper, an efficient WGDOP calculation method applying matrix multiplication that is easy for hardware implementation is proposed. In addition, the proposed method can be used when more than exactly four measurements are available. Even when using all-in-view method for positioning, the proposed method still can reduce the computational overhead. The proposed WGDOP methods with less computation are compatible with global positioning system (GPS), wireless sensor networks (WSN) and cellular communication systems. PMID:25569755

  12. Whole-genome haplotyping by dilution, amplification, and sequencing

    PubMed Central

    Kaper, Fiona; Swamy, Sajani; Klotzle, Brandy; Munchel, Sarah; Cottrell, Joseph; Bibikova, Marina; Chuang, Han-Yu; Kruglyak, Semyon; Ronaghi, Mostafa; Eberle, Michael A.; Fan, Jian-Bing

    2013-01-01

    Standard whole-genome genotyping technologies are unable to determine haplotypes. Here we describe a method for rapid and cost-effective long-range haplotyping. Genomic DNA is diluted and distributed into multiple aliquots such that each aliquot receives a fraction of a haploid copy. The DNA template in each aliquot is amplified by multiple displacement amplification, converted into barcoded sequencing libraries using Nextera technology, and sequenced in multiplexed pools. To assess the performance of our method, we combined two male genomic DNA samples at equal ratios, resulting in a sample with diploid X chromosomes with known haplotypes. Pools of the multiplexed sequencing libraries were subjected to targeted pull-down of a 1-Mb contiguous region of the X-chromosome Duchenne muscular dystrophy gene. We were able to phase the Duchenne muscular dystrophy region into two contiguous haplotype blocks with a mean length of 494 kb. The haplotypes showed 99% agreement with the consensus base calls made by sequencing the individual DNAs. We subsequently used the strategy to haplotype two human genomes. Standard genomic sequencing to identify all heterozygous SNPs in the sample was combined with dilution-amplification–based sequencing data to resolve the phase of identified heterozygous SNPs. Using this procedure, we were able to phase >95% of the heterozygous SNPs from the diploid sequence data. The N50 for a Yoruba male DNA was 702 kb whereas the N50 for a European female DNA was 358 kb. Therefore, the strategy described here is suitable for haplotyping of a set of targeted regions as well as of the entire genome. PMID:23509297

  13. Whole-genome haplotyping by dilution, amplification, and sequencing.

    PubMed

    Kaper, Fiona; Swamy, Sajani; Klotzle, Brandy; Munchel, Sarah; Cottrell, Joseph; Bibikova, Marina; Chuang, Han-Yu; Kruglyak, Semyon; Ronaghi, Mostafa; Eberle, Michael A; Fan, Jian-Bing

    2013-04-01

    Standard whole-genome genotyping technologies are unable to determine haplotypes. Here we describe a method for rapid and cost-effective long-range haplotyping. Genomic DNA is diluted and distributed into multiple aliquots such that each aliquot receives a fraction of a haploid copy. The DNA template in each aliquot is amplified by multiple displacement amplification, converted into barcoded sequencing libraries using Nextera technology, and sequenced in multiplexed pools. To assess the performance of our method, we combined two male genomic DNA samples at equal ratios, resulting in a sample with diploid X chromosomes with known haplotypes. Pools of the multiplexed sequencing libraries were subjected to targeted pull-down of a 1-Mb contiguous region of the X-chromosome Duchenne muscular dystrophy gene. We were able to phase the Duchenne muscular dystrophy region into two contiguous haplotype blocks with a mean length of 494 kb. The haplotypes showed 99% agreement with the consensus base calls made by sequencing the individual DNAs. We subsequently used the strategy to haplotype two human genomes. Standard genomic sequencing to identify all heterozygous SNPs in the sample was combined with dilution-amplification-based sequencing data to resolve the phase of identified heterozygous SNPs. Using this procedure, we were able to phase >95% of the heterozygous SNPs from the diploid sequence data. The N50 for a Yoruba male DNA was 702 kb whereas the N50 for a European female DNA was 358 kb. Therefore, the strategy described here is suitable for haplotyping of a set of targeted regions as well as of the entire genome. PMID:23509297

  14. Electrodeionization method

    DOEpatents

    Lin, YuPo J.; Hestekin, Jamie; Arora, Michelle; St. Martin, Edward J.

    2004-09-28

    An electrodeionization method for continuously producing and or separating and/or concentrating ionizable organics present in dilute concentrations in an ionic solution while controlling the pH to within one to one-half pH unit method for continuously producing and or separating and/or concentrating ionizable organics present in dilute concentrations in an ionic solution while controlling the pH to within one to one-half pH unit.

  15. A New Protocol to Detect Multiple Foodborne Pathogens with PCR Dipstick DNA Chromatography after a Six-Hour Enrichment Culture in a Broad-Range Food Pathogen Enrichment Broth

    PubMed Central

    Hayashi, Masahiro; Natori, Tatsuya; Kubota-Hayashi, Sayoko; Miyata, Machiko; Ohkusu, Kiyofumi; Kurazono, Hisao; Makino, Souichi; Ezaki, Takayuki

    2013-01-01

    A quick foodborne pathogen screening method after six-hour enrichment culture with a broad-range food pathogen enrichment broth is described. Pathogenic factors of Salmonella enterica, Shigella spp., enteroinvasive Escherichia coli, and enterohemorrhagic E. coli are amplified with a cocktail primer and rapid polymerase chain reaction (PCR), which finishes amplification in 30 min. The PCR amplicon was differentiated with a dipstick DNA chromatography assay in 5–10 min. Starting from a four- to six-hour enrichment culture, this assay was finished within 45 min. Detection sensitivity of this protocol was less than 2.5 CFU/25 g for S. enterica and 3.3 CFU/25 g for enterohemorrhagic E. coli in spiked ground meat experiments. PMID:24364031

  16. Fabrication and characterization of silver nanoparticles using Delonix elata leaf broth

    NASA Astrophysics Data System (ADS)

    Sathiya, C. K.; Akilandeswari, S.

    2014-07-01

    The synthesis of nanoparticles from plant sources has proved to be an effective and alternative method for the novel production of nanoparticles. This paper reports the bioreduction of silver nitrate into silver nanoparticle by the leaf extract of Delonix elata. The synthesized silver nanoparticles were characterized by UV-visible (UV-vis) spectroscopy, Fourier infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS), high resolution transmission electron microscope (HRTEM). In addition the size of the NPs was calculated by using Malvern Zetasizer and the stability by zeta potential. UV-vis spectra show the surface plasmon resonance (SPR) at 432 nm. This reveals the reduction of silver ions (Ag+) into silver (Ag°) and indicating the formation of silver nanoparticles (AgNPs). SEM analysis revealed the spherical shape of the particles with sizes in the range of 35-45 nm and EDS spectrum confirmed the presence of silver along with other elements in the plant metabolite. The XRD analysis showed that the AgNPs are crystalline in nature and have face-centered cubic structure. FT-IR spectra show the existence of biomolecules responsible for the reduction of silver nitrate. The size of the AgNPs estimated from particle size distribution curve shows the 70 nm. The zeta potential of AgNPs was found to be -18 mV, indicating the dispersion and stability.

  17. Convection and segregation in directional solidification of dilute and non-dilute binary alloys - Effects of ampoule and furnace design

    NASA Technical Reports Server (NTRS)

    Adornato, Peter M.; Brown, Robert A.

    1987-01-01

    A Petrov-Galerkin/finite-element method is used to analyze the effect of furnace configuration and ampoule design on the temperature field, the convection in the melt, the shape of the melt-solid interface, and the segregation of solute in the crystal, in the directional solidification of several dilute and nondilute binary semiconductor alloys. The vertical Bridgman-Stockbarger system leads to a two-cell flow structure, and the constant gradient furnace has only a single cell near the interface. Radial temperature gradients interact with the solute field to cause the previously predicted sideways diffusive instability, and addition of a solute that is less dense than the bulk melt and that is incorporated upon solidification decreases the intensity of the flow near the interface by increasing the melt density there. The present results have application to understanding of the effects on solute segregation of microgavity solidification and of applied magnetic fields.

  18. Scale-up of recombinant cutinase recovery by whole broth extraction with PEG-phosphate aqueous two-phase.

    PubMed

    Costa, M J; Cunha, M T; Cabral, J M; Aires-Barros, M R

    2000-01-01

    A whole broth extraction using an aqueous two-phase system (ATPS) composed by 5% (w/w) PEG 3350 and 15% (w/w) phosphate was used for the scale-up extraction and isolation of a recombinant Fusarium solani pisi cutinase, an extracellular mutant enzyme expressed in Saccharomyces cerevisiae, containing a fusion peptide (WP)4. The experiments were carried out at three different scales (10 ml, 1 l and 30 l). Mixing time and stirrer speed were evaluated at lab scale (1 l) with two different system compositions. Stirrer speed between 400 and 800 rpm and mixing time between 2 and 5 min led to the highest recoveries of cutinase. In all cases, inclusive of pilot scale (30 l), the equilibrium was reached after a few minutes. The performance of ATPS was reproducible within the scale range of 0.010-30 l and provided a standard deviation of the yield lower than 8%, leading to (i) a partition coefficient over 50, (ii) a yield over 95% and (iii) a concentration factor over 5. The fusion of the peptide (WP)4 to the cutinase protein enabled a 400 increase of the partition coefficient relative to the wild-type strain. PMID:11321521

  19. Antibiotic susceptibility of members of the Lactobacillus acidophilus group using broth microdilution and molecular identification of their resistance determinants.

    PubMed

    Mayrhofer, Sigrid; van Hoek, Angela H A M; Mair, Christiane; Huys, Geert; Aarts, Henk J M; Kneifel, Wolfgang; Domig, Konrad J

    2010-11-15

    The range of antibiotic susceptibility to 13 antibiotics in 101 strains of the Lactobacillus acidophilus group was examined using the lactic acid bacteria susceptibility test medium (LSM) and broth microdilution. Additionally, microarray analysis and PCR were applied to identify resistance genes responsible for the displayed resistant phenotypes in a selection of strains. In general, narrow as well as broad unimodal and bimodal MIC distributions were observed for the Lactobacillus acidophilus group and the tested antimicrobial agents. Atypically resistant strains could be determined by visual inspection of the obtained MIC ranges for ampicillin, chloramphenicol, clindamycin, erythromycin, quinupristin/dalfopristin, streptomycin and tetracycline. For most of these atypically resistant strains underlying resistance determinants were found. To our knowledge erm(A) was detected in lactobacilli for the first time within this study. Data derived from this study can be used as a basis for reviewing present microbiological breakpoints for categorization of susceptible and resistant strains within the Lactobacillus acidophilus group to assess the safety of microorganisms intended for use in food and feed applications. PMID:20888656

  20. A refrigeration temperature of 4 degrees C does not prevent static growth of Yersinia pestis in heart infusion broth.

    PubMed

    Torosian, Stephen D; Regan, Patrick M; Doran, Tara; Taylor, Michael A; Margolin, Aaron

    2009-09-01

    Multiple barriers such as inspections, testing, and proper storage conditions are used to minimize the risk of contaminated food. Knowledge of which barriers, such as refrigeration, are effective in preventing pathogen growth and persistence, can help direct the focus of efforts during food sampling. In this study, the doubling times were evaluated for 10 strains of Yersinia pestis of different genetic background cultured in heart infusion broth (HIB) kept at 4 degrees C +/- 1 degrees C under static conditions. Nine out of the 10 strains were able to grow at 4 degrees C +/- 1 degrees C. Apparent doubling times for 7 of the strains ranged from 41 to 50 h. Strain Harbin and strain D1 had apparent doubling times of 65 and 35 h, respectively, and strain O19 Ca-6 did not grow at all. Analysis of variance showed that the averaged growth data (colony forming units per mL) between strains that grew were not significantly different. The data presented here demonstrate that refrigeration alone is not an effective barrier to prevent static growth of Y. pestis in HIB. These findings provide the preliminary impetus to investigate Y. pestis growth in a variety of food matrices that may provide a similar environment as HIB. PMID:19898555

  1. Biofilm formation by Staphylococcus aureus from food contact surfaces in a meat-based broth and sensitivity to sanitizers

    PubMed Central

    de Souza, Evandro Leite; Meira, Quênia Gramile Silva; de Medeiros Barbosa, Isabella; Athayde, Ana Júlia Alves Aguiar; da Conceição, Maria Lúcia; de Siqueira Júnior, José Pinto

    2014-01-01

    This study assessed the capacity of adhesion, the detachment kinetic and the biofilm formation by Staphylococcus aureus isolated from food services on stainless steel and polypropylene surfaces (2 × 2 cm) when cultivated in a meat-based broth at 28 and 7 °C. It was also to study the efficacy of the sanitizers sodium hypochlorite (250 mg/L) and peracetic acid (30 mg/L) in inactivating the bacterial cells in the preformed biofilm. S. aureus strains adhered in high numbers regardless the assayed surface kind and incubation temperature over 72 h. Cells detachment of surfaces revealed high persistence over the incubation period. Number of cells needed for biofilm formation was noted at all experimental systems already after 3 days. Peracetic acid and sodium hypochlorite were not efficient in completely removing the cells of S. aureus adhered on polypropylene and stainless steel surfaces. From these results, the assayed strains revealed high capacity to adhere and form biofilm on polypropylene and stainless steel surfaces under different growth conditions. Moreover, the cells in biofilm matrix were resistant for total removal when submitted to the exposure to sanitizers. PMID:24948915

  2. A Laccase with HIV-1 Reverse Transcriptase Inhibitory Activity from the Broth of Mycelial Culture of the Mushroom Lentinus tigrinus

    PubMed Central

    Xu, LiJing; Wang, HeXiang; Ng, TziBun

    2012-01-01

    A 59 kDa laccase with inhibitory activity against HIV-1 reverse transcriptase (IC50 = 2.4 μM) was isolated from the broth of mycelial culture of the mushroom Lentinus tigrinus. The isolation procedure involved ion exchange chromatography on DEAE-cellulose and CM-cellulose, and gel filtration by fast protein liquid chromatography on Superdex 75. The laccase was adsorbed on both types of ion exchangers. About 95-fold purification was achieved with a 25.9% yield of the enzyme. The procedure resulted in a specific enzyme activity of 76.6 U/mg. Its N-terminal amino acid sequence was GIPDLHDLTV, which showed little similarity to other mushroom laccase and other Lentinus tigrinus strain laccase. Its characteristics were different from previously reported laccase of other Lentinus tigrinus strain. Maximal laccase activity was observed at a pH of 4 and at a temperature of 60°C, respectively. This study yielded the information about the potentially exploitable activities of Lentinus tigrinus laccase. PMID:22536022

  3. Effects of the origins of Botrytis cinerea on earthy aromas from grape broth media further inoculated with Penicillium expansum.

    PubMed

    Morales-Valle, H; Silva, L C; Paterson, R R M; Venâncio, A; Lima, N

    2011-08-01

    Earthy "off" aromas from wine and grape juice are highly detrimental to the production of quality grape products. These volatile compounds are produced on grapes by Botrytis cinerea, Penicillium expansum and/or a combination of P. expansum and B. cinerea strains. B. cinerea strains were isolated from different (a) vineyards in Spain and Portugal, (b) grape varieties (c) bunches (i.e., sound and botrytized) and (d) positions in the botrytized bunch (i.e., interior or exterior). A novel Headspace-Phase Microextraction (SPME) followed by Gas Chromatrography/Mass Spectrometry (GC-MS) dedicated to analyze geosmin, methylisoborneol (MIB), 1-octen-3-ol, fenchone and fenchol in grape broth medium was used. Approximately 50% of the B. cinerea strains induced detectable geosmin. One strain accumulated significant amounts of anisoles, demonstrating that this contamination might already occur in the vineyard. Strains from the interior of Cainho grape bunches induced more geosmin and hence it may be possible to reduce this volatile in wine by avoiding using these grapes in case of B. cinerea attack. PMID:21569951

  4. Pyruvatibacter mobilis gen. nov., sp. nov., a marine bacterium from the culture broth of Picochlorum sp. 122.

    PubMed

    Wang, Guanghua; Tang, Mingxing; Wu, Hualian; Dai, Shikun; Li, Tao; Chen, Chenghao; He, Hui; Fan, Jiewei; Xiang, Wenzhou; Li, Xiang

    2016-01-01

    A Gram-stain-negative, aerobic bacterium, designated strain GYP-11T, was isolated from the culture broth of a marine microalga, Picochloruma sp. 122. Cells were dimorphic rods; free living cells were motile by means of a single polar flagellum, and star-shaped-aggregate-forming cells were attached with stalks and non-motile. Sodium pyruvate or Tween 20 was required for growth on marine agar 2216.16S rRNA gene sequence analysis revealed that this isolate shared 94.07 % similarity with its closest type strain, Parvibaculum hydrocarboniclasticum EPR92T. Phylogenetic analyses indicated that strain GYP-11T represents a distinct lineage in a robust clade consisting of strain GYP-11T, alphaproteobacterium GMD21A06 and Candidatus Phaeomarinobacter ectocarpi Ec32. This clade was close to the genera Parvibaculum and Tepidicaulis in the order Rhizobiales. Chemotaxonomic and physiological characteristics, including cellular fatty acids and carbon source profiles, also readily distinguished strain GYP-11T from all established genera and species. Thus, it is concluded that strain GYP-11T represents a novel species of a new genus in the order Rhizobiales, for which the name Pyruvatibacter mobilis gen. nov., sp. nov. is proposed. The type strain of Pyruvatibacter mobilis is GYP-11T ( = CGMCC 1.15125T = KCTC 42509T). PMID:26476620

  5. Biofilm formation by Staphylococcus aureus from food contact surfaces in a meat-based broth and sensitivity to sanitizers.

    PubMed

    de Souza, Evandro Leite; Meira, Quênia Gramile Silva; de Medeiros Barbosa, Isabella; Athayde, Ana Júlia Alves Aguiar; da Conceição, Maria Lúcia; de Siqueira Júnior, José Pinto

    2014-01-01

    This study assessed the capacity of adhesion, the detachment kinetic and the biofilm formation by Staphylococcus aureus isolated from food services on stainless steel and polypropylene surfaces (2 × 2 cm) when cultivated in a meat-based broth at 28 and 7 °C. It was also to study the efficacy of the sanitizers sodium hypochlorite (250 mg/L) and peracetic acid (30 mg/L) in inactivating the bacterial cells in the preformed biofilm. S. aureus strains adhered in high numbers regardless the assayed surface kind and incubation temperature over 72 h. Cells detachment of surfaces revealed high persistence over the incubation period. Number of cells needed for biofilm formation was noted at all experimental systems already after 3 days. Peracetic acid and sodium hypochlorite were not efficient in completely removing the cells of S. aureus adhered on polypropylene and stainless steel surfaces. From these results, the assayed strains revealed high capacity to adhere and form biofilm on polypropylene and stainless steel surfaces under different growth conditions. Moreover, the cells in biofilm matrix were resistant for total removal when submitted to the exposure to sanitizers. PMID:24948915

  6. 17 CFR 229.506 - (Item 506) Dilution.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 17 Commodity and Securities Exchanges 2 2012-04-01 2012-04-01 false (Item 506) Dilution. 229.506 Section 229.506 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION STANDARD... (Item 506) Dilution. Where common equity securities are being registered and there is...

  7. 17 CFR 229.506 - (Item 506) Dilution.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 17 Commodity and Securities Exchanges 2 2011-04-01 2011-04-01 false (Item 506) Dilution. 229.506 Section 229.506 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION STANDARD... (Item 506) Dilution. Where common equity securities are being registered and there is...

  8. 17 CFR 229.506 - (Item 506) Dilution.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 3 2014-04-01 2014-04-01 false (Item 506) Dilution. 229.506 Section 229.506 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION STANDARD... (Item 506) Dilution. Where common equity securities are being registered and there is...

  9. 17 CFR 229.506 - (Item 506) Dilution.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 17 Commodity and Securities Exchanges 2 2013-04-01 2013-04-01 false (Item 506) Dilution. 229.506 Section 229.506 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION STANDARD... (Item 506) Dilution. Where common equity securities are being registered and there is...

  10. THE DILUTION/FLUSHING TECHNIQUE IN LAKE RESTORATION

    EPA Science Inventory

    Dilution/flushing has been documented as an effective restoration technique for Moses and Green Lakes in Washington State. The dilution water added in both lakes was low in nitrogen and phosphorus content relative to the lake or normal input water. Consequently, lake nutrient con...

  11. 40 CFR 1065.667 - Dilution air background emission correction.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.667 Dilution air background emission correction. (a) To determine the mass of background emissions to subtract... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Dilution air background...

  12. 40 CFR 1065.667 - Dilution air background emission correction.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.667 Dilution air background emission correction. (a) To determine the mass of background emissions to subtract... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Dilution air background...

  13. 40 CFR 1065.667 - Dilution air background emission correction.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.667 Dilution air background emission correction. (a) To determine the mass of background emissions to subtract... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Dilution air background...

  14. 40 CFR 1066.610 - Dilution air background correction.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... POLLUTION CONTROLS VEHICLE-TESTING PROCEDURES Calculations § 1066.610 Dilution air background correction. (a... ratio of the test fuel. You may measure a or use default values from Table 1 of 40 CFR 1065.655. b... 40 CFR 1065.655. ER28AP14.101 (c) Determine the dilution factor, DF, over the test interval...

  15. 40 CFR 1065.667 - Dilution air background emission correction.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.667 Dilution air background emission correction. (a) To determine the mass of background emissions to subtract... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Dilution air background...

  16. 40 CFR 1065.667 - Dilution air background emission correction.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.667 Dilution air background emission correction. (a) To determine the mass of background emissions to subtract... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Dilution air background...

  17. Effects of dilution on vehicle emissions of primary particles

    NASA Astrophysics Data System (ADS)

    Hayden, K. L.; Li, S.; Liggio, G.; McCurdy, M.; Chan, T.; Rostkowski, J.

    2009-12-01

    Dilution of primary aerosols from vehicles into the ambient atmosphere can change their physical and chemical characteristics. In order to study these processes, experiments were conducted in an engine testing facility at Environment Canada in Ottawa, Ontario. Exhaust from a light duty diesel engine was vented into a constant volume sampling (CVS) system where it underwent primary dilution at an ambient temperature of 25oC, leading to a primary dilution ratio of 10-15. From the CVS, the exhaust was further diluted using a combination of a Dekati ejection diluter and mixing with zero air in a flow tube, achieving secondary dilution ratios of up to 3000. Particle and gas measurements were made through multi-ports in the CVS and the flow tube using an SMPS, FMPS, AMS, and SP2, and instruments to measure CO, CO2, NOx, and total hydrocarbons (THC). Preliminary results indicate that regardless of dilution ratios, primary particles contain significant amounts of organic material that appear to reside on small black carbon cores. With increasing dilution ratios, the primary particle sizes become progressively smaller, suggesting volatilization of the adsorbed organic material. Results from various engine operating modes (simulating different driving conditions) will be presented.

  18. 21 CFR 864.5240 - Automated blood cell diluting apparatus.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Automated blood cell diluting apparatus. 864.5240 Section 864.5240 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... § 864.5240 Automated blood cell diluting apparatus. (a) Identification. An automated blood cell...

  19. 21 CFR 864.5240 - Automated blood cell diluting apparatus.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Automated blood cell diluting apparatus. 864.5240 Section 864.5240 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... § 864.5240 Automated blood cell diluting apparatus. (a) Identification. An automated blood cell...

  20. 21 CFR 864.5240 - Automated blood cell diluting apparatus.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Automated blood cell diluting apparatus. 864.5240 Section 864.5240 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... § 864.5240 Automated blood cell diluting apparatus. (a) Identification. An automated blood cell...