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Sample records for ph ruminais em

  1. Cryo-EM study of slow bee paralysis virus at low pH reveals iflavirus genome release mechanism

    PubMed Central

    Kalynych, Sergei; Füzik, Tibor; Přidal, Antonín; de Miranda, Joachim; Plevka, Pavel

    2017-01-01

    Viruses from the family Iflaviridae are insect pathogens. Many of them, including slow bee paralysis virus (SBPV), cause lethal diseases in honeybees and bumblebees, resulting in agricultural losses. Iflaviruses have nonenveloped icosahedral virions containing single-stranded RNA genomes. However, their genome release mechanism is unknown. Here, we show that low pH promotes SBPV genome release, indicating that the virus may use endosomes to enter host cells. We used cryo-EM to study a heterogeneous population of SBPV virions at pH 5.5. We determined the structures of SBPV particles before and after genome release to resolutions of 3.3 and 3.4 Å, respectively. The capsids of SBPV virions in low pH are not expanded. Thus, SBPV does not appear to form “altered” particles with pores in their capsids before genome release, as is the case in many related picornaviruses. The egress of the genome from SBPV virions is associated with a loss of interpentamer contacts mediated by N-terminal arms of VP2 capsid proteins, which result in the expansion of the capsid. Pores that are 7 Å in diameter form around icosahedral threefold symmetry axes. We speculate that they serve as channels for the genome release. Our findings provide an atomic-level characterization of the genome release mechanism of iflaviruses. PMID:28053231

  2. Dissociation energies of PH and PH+.

    NASA Astrophysics Data System (ADS)

    Reddy, R. R.; Nazeer Ahammed, Y.; Srinivasa Rao, A.; Rao, T. V. R.

    1995-12-01

    Dissociation energies for the ground electronic states of diatomic PH and PH+ are determined by fitting empirical potential functions to the respective RKRV curves using correlation coefficients. The estimated ground state dissociation energies of PH and PH+ are 3.10 and 3.20 eV respectively by the curve fitting procedure using the Lippincott potential function. The computed values are in good agreement with experimental values.

  3. Plant Habitat (PH)

    NASA Technical Reports Server (NTRS)

    Onate, Bryan

    2016-01-01

    The International Space Station (ISS) will soon have a platform for conducting fundamental research of Large Plants. Plant Habitat (PH) is designed to be a fully controllable environment for high-quality plant physiological research. PH will control light quality, level, and timing, temperature, CO2, relative humidity, and irrigation, while scrubbing ethylene. Additional capabilities include leaf temperature and root zone moisture and oxygen sensing. The light cap will have red (630 nm), blue (450 nm), green (525 nm), far red (730 nm) and broad spectrum white LEDs. There will be several internal cameras (visible and IR) to monitor and record plant growth and operations.

  4. pH Basics

    ERIC Educational Resources Information Center

    Lunelli, Bruno; Scagnolari, Francesco

    2009-01-01

    The exposition of the pervasive concept of pH, of its foundations and implementation as a meaningful quantitative measurement, in nonspecialist university texts is often not easy to follow because too many of its theoretical and operative underpinnings are neglected. To help the inquiring student we provide a concise introduction to the depth just…

  5. pH optrode

    DOEpatents

    Northrup, M. Allen; Langry, Kevin C.

    1993-01-01

    A process is provided for forming a long-lasting, stable, pH-sensitive dye-acrylamide copolymer useful as a pH-sensitive material for use in an optrode or other device sensitive to pH. An optrode may be made by mechanically attaching the copolymer to a sensing device such as an optical fiber.

  6. Ph.D. shortage

    NASA Astrophysics Data System (ADS)

    The late 1990s will see a shortage of Ph.D. graduates, according to the Association of American Universities, Washington, D.C. AAU's new comprehensive study, “The Ph.D. Shortage: The Federal Role,” reports that competition for new Ph.D.s is already intense and can only intensify because demand is greater than supply in both academic and nonacademic markets.Doctoral education plays an increasingly important role in U.S. research and development programs. Students have a pivotal part in doing research and enriching it with new ideas. The AAU report says that graduate students are “major determinants of the creativity and productivity of U.S. academic research, the source of more than 50% of the nation's basic research.’ The market for doctoral education extends beyond the university. In 1985, about 43% of all Ph.D.s employed in this country were working outside higher education; the demand for doctorate recipients in nonacademic sectors continues to grow.

  7. 17-4 PH and 15-5 PH

    NASA Technical Reports Server (NTRS)

    Johnson, Howard T.

    1995-01-01

    17-4 PH and 15-5 PH are extremely useful and versatile precipitation-hardening stainless steels. Armco 17-4 PH is well suited for the magnetic particle inspection requirements of Aerospace Material Specification. Armco 15-5 PH and 17-4 PH are produced in billet, plate, bar, and wire. Also, 15-5 PH is able to meet the stringent mechanical properties required in the aerospace and nuclear industries. Both products are easy to heat treat and machine, making them very useful in many applications.

  8. Energy separations for the electronic states of PH -2,PH 2 and PH +2

    NASA Astrophysics Data System (ADS)

    Balasubramanian, K.

    1993-03-01

    All-electron complete-active space multi-configuration self-consistent field (CASSCF) followed by second-order configuration interaction (SOCI) calculations in conjunction with large P(13s10p3d2flg/7s6p3d2flg) and H (10s5p1d/8s5p1d) basis sets are made on the electronic states of PH -2, PH 2 and PH +2. We compute the adiabatic electron affinities of PH 2 and PH. The 3B 1-X 1A 1, 1B 1-X 1A 1 energy separations of PH +2 and the 2A 1-X 2B 1 energy separation of PH 2 are computed.

  9. The pH Game.

    ERIC Educational Resources Information Center

    Chemecology, 1996

    1996-01-01

    Describes a game that can be used to teach students about the acidity of liquids and substances around their school and enable them to understand what pH levels tell us about the environment. Students collect samples and measure the pH of water, soil, plants, and other natural material. (DDR)

  10. Urine pH test

    MedlinePlus

    ... pubmed/7797810 . Read More Acid loading test (pH) Acute kidney failure Alkalosis Chronic obstructive pulmonary disease Diabetic ketoacidosis Diarrhea - overview Distal renal tubular acidosis Gastric suction Interstitial nephritis Kidney stones ...

  11. Exercise and Pulmonary Hypertension (PH)

    MedlinePlus

    ... Process: Some First Steps Adoption Success Story Watch Classroom Recordings Empowered Patient Online Toolkit Tab 1: Very ... Kathy Groebner Education Programs Patients and Caregivers PHA Classroom PHA on the Road: PH Patients and Families ...

  12. Esophageal pH monitoring

    MedlinePlus

    ... test can also be done during upper GI endoscopy by clipping a pH monitor to the lining of the esophagus. ... esophagitis : Barium swallow Esophagogastroduodenoscopy (also called upper GI endoscopy)

  13. PhEDEx Data Service

    NASA Astrophysics Data System (ADS)

    Egeland, Ricky; Wildish, Tony; Huang, Chih-Hao

    2010-04-01

    The PhEDEx Data Service provides access to information from the central PhEDEx database, as well as certificate-authenticated managerial operations such as requesting the transfer or deletion of data. The Data Service is integrated with the "SiteDB" service for fine-grained access control, providing a safe and secure environment for operations. A plug-in architecture allows server-side modules to be developed rapidly and easily by anyone familiar with the schema, and can automatically return the data in a variety of formats for use by different client technologies. Using HTTP access via the Data Service instead of direct database connections makes it possible to build monitoring web-pages with complex drill-down operations, suitable for debugging or presentation from many aspects. This will form the basis of the new PhEDEx website in the near future, as well as providing access to PhEDEx information and certificate-authenticated services for other CMS dataflow and workflow management tools such as CRAB, WMCore, DBS and the dashboard. A PhEDEx command-line client tool provides one-stop access to all the functions of the PhEDEx Data Service interactively, for use in simple scripts that do not access the service directly. The client tool provides certificate-authenticated access to managerial functions, so all the functions of the PhEDEx Data Service are available to it. The tool can be expanded by plug-ins which can combine or extend the client-side manipulation of data from the Data Service, providing a powerful environment for manipulating data within PhEDEx.

  14. Programmable pH buffers

    DOEpatents

    Gough, Dara Van; Huber, Dale L.; Bunker, Bruce C.; Roberts, Mark E.

    2017-01-24

    A programmable pH buffer comprises a copolymer that changes pK.sub.a at a lower critical solution temperature (LCST) in water. The copolymer comprises a thermally programmable polymer that undergoes a hydrophobic-to-hydrophilic phase change at the LCST and an electrolytic polymer that exhibits acid-base properties that are responsive to the phase change. The programmable pH buffer can be used to sequester CO.sub.2 into water.

  15. Intragastric pH Monitoring,

    DTIC Science & Technology

    1993-10-01

    disposable sensor.. hnt Care 13. Peterson WL. GI bleeding. In: Sleisenger MH, Fordtran IS, Med 1988;14:232-5. ,. eds. Gastrointestinal disease: pathophysiology ... diagnosis and 27. Fimmel CL, Etienne A, Cilluffo T, et al. Long-term ambu- management, Vol I. 4th ed. Philadelphia: WB Saunders, latory gastric pH

  16. Making pH Tangible.

    ERIC Educational Resources Information Center

    McIntosh, Elizabeth; Moss, Robert

    1995-01-01

    Presents a laboratory exercise in which students test the pH of different substances, study the effect of a buffer on acidic solutions by comparing the behavior of buffered and unbuffered solutions upon the addition of acid, and compare common over-the-counter antacid remedies. (MKR)

  17. The fluorescence properties of the phenylated fullerenes C 70Ph 4, C 70Ph 6, C 70Ph 8, and C 70Ph 10 in room temperature solutions

    NASA Astrophysics Data System (ADS)

    Schwell, Martin; Gustavsson, Thomas; Marguet, Sylvie; Vaissière, Benoı̂t de La; Wachter, Norbert K.; Birkett, Paul R.; Mialocq, Jean-Claude; Leach, Sydney

    2001-12-01

    The emission and excitation spectra of four phenylated [70] fullerenes, C 70Ph 4, C 70Ph 6, C 70Ph 8, and C 70Ph 10 in cyclohexane and toluene solutions have been measured. The fluorescence spectra and related excited state properties are found to depend strongly on the number of attached phenyl groups, but with no systematic trends. Quantum yields and fluorescence lifetimes were measured for C 70Ph 6, C 70Ph 8, and C 70Ph 10, allowing the determination of S1 → S0 radiative transition rates kR. It is found that kR for C 70Ph 10 is about six times larger than for the other compounds. This is consistent with measured absorbtivities for these compounds. The particular character of C 70Ph 10 is also manifested by its higher intersystem crossing rate kISC.

  18. Alkaline pH sensor molecules.

    PubMed

    Murayama, Takashi; Maruyama, Ichiro N

    2015-11-01

    Animals can survive only within a narrow pH range. This requires continual monitoring of environmental and body-fluid pH. Although a variety of acidic pH sensor molecules have been reported, alkaline pH sensor function is not well understood. This Review describes neuronal alkaline pH sensors, grouped according to whether they monitor extracellular or intracellular alkaline pH. Extracellular sensors include the receptor-type guanylyl cyclase, the insulin receptor-related receptor, ligand-gated Cl- channels, connexin hemichannels, two-pore-domain K+ channels, and transient receptor potential (TRP) channels. Intracellular sensors include TRP channels and gap junction channels. Identification of molecular mechanisms underlying alkaline pH sensing is crucial for understanding how animals respond to environmental alkaline pH and how body-fluid pH is maintained within a narrow range.

  19. The pH of antiseptic cleansers

    PubMed Central

    Kulthanan, Kanokvalai; Varothai, Supenya; Nuchkull, Piyavadee

    2014-01-01

    Background Daily bathing with antiseptic cleansers are proposed by some physicians as an adjunctive management of atopic dermatitis (AD). As atopic skin is sensitive, selection of cleansing products becomes a topic of concern. Objective Our purpose is to evaluate the pH of various antiseptic body cleansers to give an overview for recommendation to patients with AD. Methods Commonly bar and liquid cleansers consisted of antiseptic agents were measured for pH using pH meter and pH-indicator strips. For comparison, mild cleansers and general body cleansers were also measured. Results All cleansing bars had pH 9.8-11.3 except syndet bar that had neutral pH. For liquid cleansers, three cleansing agents had pH close to pH of normal skin, one of antiseptic cleansers, one of mild cleansers and another one of general cleansers. The rest of antiseptic cleansers had pH 8.9-9.6 while mild cleansers had pH 6.9-7.5. Syndet liquid had pH 7 and general liquid cleansers had pH 9.6. Conclusion The pH of cleanser depends on composition of that cleanser. Adding antiseptic agents are not the only factor determining variation of pH. Moreover, benefit of antiseptic properties should be considered especially in cases of infected skin lesions in the selection of proper cleansers for patients with AD. PMID:24527408

  20. Fetal scalp pH testing

    MedlinePlus

    Fetal scalp blood; Scalp pH testing; Fetal blood testing - scalp; Fetal distress - fetal scalp testing; Labor - fetal scalp testing ... a baby. In these cases, testing the scalp pH can help the doctor decide whether the fetus ...

  1. Acid loading test (pH)

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003615.htm Acid loading test (pH) To use the sharing features on this page, please enable JavaScript. The acid loading test (pH) measures the ability of the ...

  2. Functional photoacoustic microscopy of pH

    NASA Astrophysics Data System (ADS)

    Chatni, M. Rameez; Yao, Junjie; Danielli, Amos; Favazza, Christopher P.; Maslov, Konstantin I.; Wang, Lihong V.

    2012-02-01

    pH is a tightly regulated indicator of metabolic activity. In mammalian systems, imbalance of pH regulation may result from or result in serious illness. Even though the regulation system of pH is very robust, tissue pH can be altered in many diseases such as cancer, osteoporosis and diabetes mellitus. Traditional high-resolution optical imaging techniques, such as confocal microscopy, routinely image pH in cells and tissues using pH sensitive fluorescent dyes, which change their fluorescence properties with the surrounding pH. Since strong optical scattering in biological tissue blurs images at greater depths, high-resolution pH imaging is limited to penetration depths of 1mm. Here, we report photoacoustic microscopy (PAM) of commercially available pH-sensitive fluorescent dye in tissue phantoms. Using both opticalresolution photoacoustic microscopy (OR-PAM), and acoustic resolution photoacoustic microscopy (AR-PAM), we explored the possibility of recovering the pH values in tissue phantoms. In this paper, we demonstrate that PAM was capable of recovering pH values up to a depth of 2 mm, greater than possible with other forms of optical microscopy.

  3. Improved reliability of pH measurements.

    PubMed

    Spitzer, Petra; Werner, Barbara

    2002-11-01

    Measurements of pH are performed on a large scale at laboratory level, and in industry. To meet the quality-control requirements and other technical specifications there is a need for traceability in measurement results. The prerequisite for the international acceptance of analytical data is reliability. To measure means to compare. Comparability entails use of recognised references to which the standard buffer solutions used for calibration of pH meter-electrode assemblies can be traced. The new recommendation on the measurement of pH recently published as a provisional document by the International Union on Pure and Applied Chemistry (IUPAC) enables traceability for measured pH values to a conventional reference frame which is recognised world-wide. The primary method for pH will be described. If analytical data are to be accepted internationally it is necessary to demonstrate the equivalence of the national traceability structures, including national measurement standards. For the first time key comparisons for pH have been performed by the Consultative Committee for Amount of Substance (CCQM, set up by the International Bureau of Weights and Measures, BIPM) to assess the equivalence of the national measurement procedures used to determine the pH of primary standard buffer solutions. The results of the first key comparison on pH CCQM-K9, and other international initiatives to improve the consistency of the results of measurement for pH, are reported.

  4. pH Meter probe assembly

    DOEpatents

    Hale, C.J.

    1983-11-15

    An assembly for mounting a pH probe in a flowing solution, such as a sanitary sewer line, which prevents the sensitive glass portion of the probe from becoming coated with grease, oil, and other contaminants, whereby the probe gives reliable pH indication over an extended period of time. The pH probe assembly utilizes a special filter media and a timed back-rinse feature for flushing clear surface contaminants of the filter. The flushing liquid is of a known pH and is utilized to check performance of the probe. 1 fig.

  5. pH Meter probe assembly

    DOEpatents

    Hale, Charles J.

    1983-01-01

    An assembly for mounting a pH probe in a flowing solution, such as a sanitary sewer line, which prevents the sensitive glass portion of the probe from becoming coated with grease, oil, and other contaminants, whereby the probe gives reliable pH indication over an extended period of time. The pH probe assembly utilizes a special filter media and a timed back-rinse feature for flushing clear surface contaminants of the filter. The flushing liquid is of a known pH and is utilized to check performance of the probe.

  6. pH. Agricultural Lesson Plans.

    ERIC Educational Resources Information Center

    Southern Illinois Univ., Carbondale. Dept. of Agricultural Education and Mechanization.

    This lesson plan is intended for use in conducting classes on the effect of pH on plant growth. Presented first are an attention step/problem statement and a series of questions and answers designed to convey general information about soil pH and its effect on plants. The following topics are among those discussed: acidity and alkalinity; the…

  7. pH [Measure of Acidity].

    ERIC Educational Resources Information Center

    Henderson, Paula

    This autoinstructional program deals with the study of the pH of given substances by using litmus and hydrion papers. It is a learning activity directed toward low achievers involved in the study of biology at the secondary school level. The time suggested for the unit is 25-30 minutes (plus additional time for further pH testing). The equipment…

  8. Middle School and pH?

    ERIC Educational Resources Information Center

    Herricks, Susan

    2007-01-01

    A local middle school requested that the Water Center of Advanced Materials for Purification of Water With Systems (WaterCAMPWS), a National Science Foundation Science and Technology Center, provide an introduction to pH for their seventh-grade water-based service learning class. After sorting through a multitude of information about pH, a…

  9. Inexpensive and Disposable pH Electrodes

    ERIC Educational Resources Information Center

    Goldcamp, Michael J.; Conklin, Alfred; Nelson, Kimberly; Marchetti, Jessica; Brashear, Ryan; Epure, Emily

    2010-01-01

    Inexpensive electrodes for the measurement of pH have been constructed using the ionophore tribenzylamine for sensing H[superscript +] concentrations. Both traditional liquid-membrane electrodes and coated-wire electrodes have been constructed and studied, and both exhibit linear, nearly Nernstian responses to changes in pH. Measurements of pH…

  10. Determination Of Ph Including Hemoglobin Correction

    DOEpatents

    Maynard, John D.; Hendee, Shonn P.; Rohrscheib, Mark R.; Nunez, David; Alam, M. Kathleen; Franke, James E.; Kemeny, Gabor J.

    2005-09-13

    Methods and apparatuses of determining the pH of a sample. A method can comprise determining an infrared spectrum of the sample, and determining the hemoglobin concentration of the sample. The hemoglobin concentration and the infrared spectrum can then be used to determine the pH of the sample. In some embodiments, the hemoglobin concentration can be used to select an model relating infrared spectra to pH that is applicable at the determined hemoglobin concentration. In other embodiments, a model relating hemoglobin concentration and infrared spectra to pH can be used. An apparatus according to the present invention can comprise an illumination system, adapted to supply radiation to a sample; a collection system, adapted to collect radiation expressed from the sample responsive to the incident radiation; and an analysis system, adapted to relate information about the incident radiation, the expressed radiation, and the hemoglobin concentration of the sample to pH.

  11. Endoscopic sensing of alveolar pH

    PubMed Central

    Choudhury, D.; Tanner, M. G.; McAughtrie, S.; Yu, F.; Mills, B.; Choudhary, T. R.; Seth, S.; Craven, T. H.; Stone, J. M.; Mati, I. K.; Campbell, C. J.; Bradley, M.; Williams, C. K. I.; Dhaliwal, K.; Birks, T. A.; Thomson, R. R.

    2016-01-01

    Previously unobtainable measurements of alveolar pH were obtained using an endoscope-deployable optrode. The pH sensing was achieved using functionalized gold nanoshell sensors and surface enhanced Raman spectroscopy (SERS). The optrode consisted of an asymmetric dual-core optical fiber designed for spatially separating the optical pump delivery and signal collection, in order to circumvent the unwanted Raman signal generated within the fiber. Using this approach, we demonstrate a ~100-fold increase in SERS signal-to-fiber background ratio, and demonstrate multiple site pH sensing with a measurement accuracy of ± 0.07 pH units in the respiratory acini of an ex vivo ovine lung model. We also demonstrate that alveolar pH changes in response to ventilation. PMID:28101415

  12. EMS Student Handbook.

    ERIC Educational Resources Information Center

    Ogle, Patrick

    This student guide is one of a series of self-contained materials for students enrolled in an emergency medical services (EMS) training program. Discussed in the individual sections of the guide are the following topics: the purpose and history of EMS professionals; EMS training, certification and examinations (national and state certification and…

  13. Exhaled breath condensate pH assays.

    PubMed

    Davis, Michael D; Hunt, John

    2012-08-01

    Airway pH is central to the physiologic function and cellular biology of the airway. The causes of airway acidification include (1) hypopharyngeal gastric acid reflux with or without aspiration through the vocal cords, (2) inhalation of acid fog or gas (such as chlorine), and (3) intrinsic airway acidification caused by altered airway pH homeostasis in infectious and inflammatory disease processes. The recognition that relevant airway pH deviations occur in lung diseases is opening doors to new simple and inexpensive therapies. This recognition has resulted partly from the ability to use exhaled breath condensate as a window on airway acid-base balance.

  14. EM International. Volume 1

    SciTech Connect

    Not Available

    1993-07-01

    It is the intent of EM International to describe the Office of Environmental Restoration and Waste Management`s (EM`s) various roles and responsibilities within the international community. Cooperative agreements and programs, descriptions of projects and technologies, and synopses of visits to international sites are all highlighted in this semiannual journal. Focus on EM programs in this issue is on international collaboration in vitrification projects. Technology highlights covers: in situ sealing for contaminated sites; and remote sensors for toxic pollutants. Section on profiles of countries includes: Arctic contamination by the former Soviet Union, and EM activities with Germany--cooperative arrangements.

  15. Coping with PH over the Long Term

    MedlinePlus

    ... Process: Some First Steps Adoption Success Story Watch Classroom Recordings Empowered Patient Online Toolkit Tab 1: Very ... Kathy Groebner Education Programs Patients and Caregivers PHA Classroom PHA on the Road: PH Patients and Families ...

  16. Effect of two mouthwashes on salivary ph.

    PubMed

    Belardinelli, Paola A; Morelatto, Rosana A; Benavidez, Tomás E; Baruzzi, Ana M; López de Blanc, Silvia A

    2014-01-01

    To analyze the effect of two mouthwashes on salivary pH and correlate it with age, buffer capacity and saliva flow rate in healthy volunteers, a crossover phase IV clinical study involving three age-based groups was designed. Two commercial mouthwashes (MW), Cool Mint ListerineR (MWa) and Periobacter R (MWb) were used. The unstimulated saliva of each individual was first characterized by measuring flow rate, pH, and buffer capacity. Salivary pH was evaluated before rinsing with a given MW, immediately after rinsing, 5 minutes later, and then every 10 min (at 15, 25, 35 min) until the baseline pH was recovered. Paired t-test, ANOVA with a randomized block design, and Pearson correlation tests were used. Averages were 0.63 mL/min, 7.06, and 0.87 for flow rate, pH, and buffer capacity, respectively. An immediate significant increase in salivary pH was observed after rinsing, reaching average values of 7.24 (MWb) and 7.30 (MWa), which declined to an almost stable value 15 minutes. The great increase in salivary pH, after MW use shows that saliva is a dynamic system, and that the organism is capable of responding to a stimulus with changes in its composition. It is thus evident that pH of the external agent alone is not a good indicator for its erosive potential because biological systems tend to neutralize it. The results of this study enhance the importance of in vivo measurements and reinforce the concept of the protective action of saliva.

  17. Eukaryotic diversity at pH extremes

    PubMed Central

    Amaral-Zettler, Linda A.

    2013-01-01

    Extremely acidic (pH < 3) and extremely alkaline (pH > 9) environments support a diversity of single-cell and to a lesser extent, multicellular eukaryotic life. This study compared alpha and beta diversity in eukaryotic communities from seven diverse aquatic environments with pH values ranging from 2 to 11 using massively-parallel pyrotag sequencing targeting the V9 hypervariable region of the 18S ribosomal RNA (rRNA) gene. A total of 946 operational taxonomic units (OTUs) were recovered at a 6% cut-off level (94% similarity) across the sampled environments. Hierarchical clustering of the samples segregated the communities into acidic and alkaline groups. Similarity percentage (SIMPER) analysis followed by indicator OTU analysis (IOA) and non-metric multidimensional scaling (NMDS) were used to determine which characteristic groups of eukaryotic taxa typify acidic or alkaline extremes and the extent to which pH explains eukaryotic community structure in these environments. Spain's Rio Tinto yielded the fewest observed OTUs while Nebraska Sandhills alkaline lakes yielded the most. Distinct OTUs, including metazoan OTUs, numerically dominated pH extreme sites. Indicator OTUs included the diatom Pinnularia and unidentified opisthokonts (Fungi and Filasterea) in the extremely acidic environments, and the ciliate Frontonia across the extremely alkaline sites. Inferred from NMDS, pH explained only a modest fraction of the variation across the datasets, indicating that other factors influence the underlying community structure in these environments. The findings from this study suggest that the ability for eukaryotes to adapt to pH extremes over a broad range of values may be rare, but further study of taxa that can broadly adapt across diverse acidic and alkaline environments, respectively present good models for understanding adaptation and should be targeted for future investigations. PMID:23335919

  18. Continuous direct measurement of intracellular chloride and pH in frog skeletal muscle

    PubMed Central

    Bolton, T. B.; Vaughan-Jones, R. D.

    1977-01-01

    1. Ion-sensitive electrodes (made with a chloride-sensitive ion-exchange resin) were used to measure the internal chloride activity (aiCl) of frog sartorius fibres at 25° C. 2. The internal pH (pHi) of other sartorius fibres was measured with a recessed tip pH-sensitive electrode (made with pH-sensitive glass). 3. In normal bicarbonate-free solution (containing 2·5 mM potassium), the average chloride equilibrium potential, ECl (calculated from aiCl and the measured chloride activity of the external solution (aoCl) was 87·7 ± 1·7 mV (mean ± S.E.; n = 16) in fibres where the average membrane potential, Em, was 88·3 ± 1·5 mV (mean ± S.E.; n = 16). In experiments where aiCl was varied between about 1 and 10 mM (which corresponds to values of Em between about -105 and -50 mV) ECl was within 1-3 mV of Em at equilibrium. These measurements of aiCl were obtained from the potential difference between the chloride-sensitive electrode and an intracellular indifferent micro-electrode filled with potassium chloride. If a potassium sulphate-filled indifferent micro-electrode was used, then values of aiCl below about 5 mM were erroneously high, probably due to interference from other sarcoplasmic ions at the indifferent electrode. 4. In solutions containing 15 mM bicarbonate and gassed with 5% CO2, pHi was 6·9, corresponding to an internal bicarbonate concentration of 7·6 mM. ECl measured in this solution was some 4 mV positive to Em. Most of the difference between ECl and Em could be ascribed to interference by sarcoplasmic bicarbonate on the basis of selectivity measurements of chloride against bicarbonate made on the ion-exchange resin in the relevant range of aCl. 5. If bicarbonate/CO2 in the external solution was replaced by HEPES/pure O2 at constant pH, then pHi rose from 6·88 ± 0·02 (mean ± S.E.) to 7·05 ± 0·02. A change in external pH of 1 unit caused pHi to change by about 0·02 unit and the intracellular buffering power was calculated to be about 35

  19. A Nanocrystal-based Ratiometric pH Sensor for Natural pH Ranges.

    PubMed

    Somers, Rebecca C; Lanning, Ryan M; Snee, Preston T; Greytak, Andrew B; Jain, Rakesh K; Bawendi, Moungi G; Nocera, Daniel G

    A ratiometric fluorescent pH sensor based on CdSe/CdZnS nanocrystal quantum dots (NCs) has been designed for biological pH ranges. The construct is formed from the conjugation of a pH dye (SNARF) to NCs coated with a poly(amido amine) (PAMAM) dendrimer. The sensor exhibits a well-resolved ratio response at pH values between 6 and 8 under linear or two-photon excitation, and in the presence of a 4% bovine serum albumin (BSA) solution.

  20. A Nanocrystal-based Ratiometric pH Sensor for Natural pH Ranges

    PubMed Central

    Somers, Rebecca C.; Lanning, Ryan M.; Snee, Preston T.; Greytak, Andrew B.; Jain, Rakesh K.

    2014-01-01

    Summary A ratiometric fluorescent pH sensor based on CdSe/CdZnS nanocrystal quantum dots (NCs) has been designed for biological pH ranges. The construct is formed from the conjugation of a pH dye (SNARF) to NCs coated with a poly(amido amine) (PAMAM) dendrimer. The sensor exhibits a well–resolved ratio response at pH values between 6 and 8 under linear or two–photon excitation, and in the presence of a 4% bovine serum albumin (BSA) solution. PMID:26413260

  1. Leveraging EMS and VPP

    DTIC Science & Technology

    2009-05-01

    Elements of EMS  International Standards Organization ( ISO ) 14001 , Environmental Management Systems  The Key Elements of EMS: - Policy - Planning...wingman-- ON and OFF duty Fully Conforming vs. Fully Implemented  “Fully Conforming”  Meets standards established in ISO 14001  ESOH council...e n c e Every airman looking out for his wingman-- ON and OFF duty EMS & VPP Commonalities Environmental Management System ISO 14001 : 2004 Voluntary

  2. Thermally programmable pH buffers.

    PubMed

    Van Gough, Dara; Bunker, Bruce C; Roberts, Mark E; Huber, Dale L; Zarick, Holly F; Austin, Mariah J; Wheeler, Jill S; Moore, Diana; Spoerke, Erik D

    2012-11-01

    Many reactions in both chemistry and biology rely on the ability to precisely control and fix the solution concentrations of either protons or hydroxide ions. In this report, we describe the behavior of thermally programmable pH buffer systems based on the copolymerization of varying amounts of acrylic acid (AA) groups into N-isopropylacrylamide polymers. Because the copolymers undergo phase transitions upon heating and cooling, the local environment around the AA groups can be reversibly switched between hydrophobic and hydrophilic states affecting the ionization behavior of the acids. Results show that moderate temperature variations can be used to change the solution pH by two units. However, results also indicate that the nature of the transition and its impact on the pH values are highly dependent on the AA content and the degree of neutralization.

  3. Fiber-Optic pH Sensor

    NASA Astrophysics Data System (ADS)

    Ganesh, A. Balaji; Radhakrishnan, T. K.

    The new enhancement in the determination of pH using optical fiber system is described here. This work uses the membrane made of cellulose acetate membrane for reagent immobilization and congo red (pKa 3.7) and neutral red (pKa 7.2) as pH indicators. An effective covalent chemical binding procedure is used to immobilize the indicatorsE The response time, reversibility, linear range, reproducibility, and long-term stability of fiber optic sensor with congo red as well as neutral red have been determined. The linear range measured for the sensor based on the congo red and neutral red is 4.2-6.3 and 4.1-9.0, respectively. The response time of sensor membrane is measured by varying the substance pH values between 11.0 and 2.0.

  4. Composting of rice straw with effective microorganisms (EM) and its influence on compost quality

    PubMed Central

    2013-01-01

    This study aims to assess the effect of EM application on the composting process of rice straw with goat manure and green waste and to evaluate the quality of both compost treatments. There are two treatment piles in this study, in which one pile was applied with EM and another pile without EM. Each treatment was replicated three times with 90 days of composting duration. The parameters for the temperature, pH, TOC and C/N ratio, show that decomposition of organic matter occurs during the 90-day period. The t-test conducted shows that there is a significant difference between compost with EM and compost without EM. The application of EM in compost increases the macro and micronutrient content. The following parameters support this conclusion: compost applied with EM has more N, P and K content (P < 0.05) compared to compost without EM. Although the Fe in compost with EM is much higher (P < 0.05) than in the compost without EM, for Zn and Cu, there is no significant difference between treatments. This study suggests that the application of EM is suitable to increase the mineralization in the composting process. The final resultant compost indicated that it was in the range of the matured level and can be used without any restriction. PMID:23390930

  5. Differential genotoxicity of diphenyl diselenide (PhSe)2 and diphenyl ditelluride (PhTe)2.

    PubMed

    Meinerz, Daiane Francine; Allebrandt, Josiane; Mariano, Douglas O C; Waczuk, Emily P; Soares, Felix Antunes; Hassan, Waseem; Rocha, João Batista T

    2014-01-01

    Organoselenium compounds have been pointed out as therapeutic agents. In contrast, the potential therapeutic aspects of tellurides have not yet been demonstrated. The present study evaluated the comparative toxicological effects of diphenyl diselenide (PhSe)2 and diphenyl ditelluride (PhTe)2 in mice after in vivo administration. Genotoxicity (as determined by comet assay) and mutagenicicity were used as end-points of toxicity. Subcutaneous administration of high doses of (PhSe)2 or (PhTe)2 (500 µmol/kg) caused distinct genotoxicity in mice. (PhSe)2 significantly decreased the DNA damage index after 48 and 96 h of its injection (p < 0.05). In contrast, (PhTe) caused a significant increase in DNA damage (p < 0.05) after 48 and 96 h of intoxication. (PhSe)2 did not cause mutagenicity but (PhTe)2 increased the micronuclei frequency, indicating its mutagenic potential. The present study demonstrated that acute in vivo exposure to ditelluride caused genotoxicity in mice, which may be associated with pro-oxidant effects of diphenyl ditelluride. In addition, the use of this compound and possibly other related tellurides must be carefully controlled.

  6. Evaluation of fluorimetric pH sensors for bioprocess monitoring at low pH.

    PubMed

    Janzen, Nils H; Schmidt, Michael; Krause, Christian; Weuster-Botz, Dirk

    2015-09-01

    Optical chemical sensors are the standard for pH monitoring in small-scale bioreactors such as microtiter plates, shaking flasks or other single-use bioreactors. The dynamic pH range of the so far commercially available fluorescent pH sensors applied in small-scale bioreactors is restricted to pH monitoring around neutral pH, although many fermentation processes are performed at pH < 6 on industrial scale. Thus, two new prototype acidic fluorescence pH sensors immobilized in single-use stirred-tank bioreactors, one with excitation at 470 nm and emission at 550 nm (sensor 470/550) and the other with excitation at 505 nm and emission at 600 nm (sensor 505/600), were characterized with respect to dynamic ranges and operational stability in representative fermentation media. Best resolution and dynamic range was observed with pH sensor 505/600 in mineral medium (dynamic range of 3.9 < pH < 7.2). Applying the same pH sensors to complex medium results in a drastic reduction of resolution and dynamic ranges. Yeast extract in complex medium was found to cause background fluorescence at the sensors' operating wavelength combinations. Optical isolation of the sensor by adding a black colored polymer layer above the sensor spot and fixing an aperture made of adhesive photoresistant foil between the fluorescence reader and the transparent bottom of the polystyrene reactors enabled full re-establishment of the sensor's characteristics. Reliability and operational stability of sensor 505/600 was shown by online pH monitoring (4.5 < pH < 5.8) of parallel anaerobic batch fermentations of Clostridium acetobutylicum for the production of acetone, butanol and ethanol (ABE) with offline pH measurements with a standard glass electrode as reference.

  7. What My Ph.D. Taught Me

    ERIC Educational Resources Information Center

    Levenstein, Jessica

    2013-01-01

    The author started in the Ph.D. program in comparative literature at Princeton in 1992, a year after she graduated from college. She fell in love with mythology and the classical traditions and find herself teaching literature. In the remainder of her time at Princeton, she precepted for four or five more classes, got the chance to join the…

  8. The Economic Contribution of PhDs

    ERIC Educational Resources Information Center

    Casey, Bernard H.

    2009-01-01

    This paper looks at what the value of a doctorate is, both to employers in particular and to society and the economy at large. Given the emphasis many universities and funding agencies/governments are putting upon the development of PhD programmes, this is an issue deserving attention. The paper tries to show how two separate but interrelated…

  9. PH Sensitive WO3-Based Microelectrochemical Transistors.

    DTIC Science & Technology

    1986-09-22

    a WO3 target. The cyclic voltammetry of these microelectrodes indicates that WO3 connects individual microelectrodes, since the voltammogram of a...transistor that is sensitive to pH. The cyclic voltammetry is pH-dependent and consistent with pH-dependent transistor characteristics, which indicate that the

  10. Development of sulfonamide AKT PH domain inhibitors.

    PubMed

    Ahad, Ali Md; Zuohe, Song; Du-Cuny, Lei; Moses, Sylvestor A; Zhou, Li Li; Zhang, Shuxing; Powis, Garth; Meuillet, Emmanuelle J; Mash, Eugene A

    2011-03-15

    Disruption of the phosphatidylinositol 3-kinase/AKT signaling pathway can lead to apoptosis in cancer cells. Previously we identified a lead sulfonamide that selectively bound to the pleckstrin homology (PH) domain of AKT and induced apoptosis when present at low micromolar concentrations. To examine the effects of structural modification, a set of sulfonamides related to the lead compound was designed, synthesized, and tested for binding to the expressed PH domain of AKT using a surface plasmon resonance-based competitive binding assay. Cellular activity was determined by means of an assay for pAKT production and a cell killing assay using BxPC-3 cells. The most active compounds in the set are lipophilic and possess an aliphatic chain of the proper length. Results were interpreted with the aid of computational modeling. This paper represents the first structure-activity relationship (SAR) study of a large family of AKT PH domain inhibitors. Information obtained will be used in the design of the next generation of inhibitors of AKT PH domain function.

  11. Teaching Physics Using PhET Simulations

    ERIC Educational Resources Information Center

    Wieman, C. E.; Adams, W. K.; Loeblein, P.; Perkins, K. K.

    2010-01-01

    PhET Interactive Simulations (sims) are now being widely used in teaching physics and chemistry. Sims can be used in many different educational settings, including lecture, individual or small group inquiry activities, homework, and lab. Here we will highlight a few ways to use them in teaching, based on our research and experiences using them in…

  12. Ph.D.'s and the Marketplace.

    ERIC Educational Resources Information Center

    Harvey, James

    Throughout the last decade, Ph.D. recipients were accustomed to a job market in which demand for their services far exceeded supply. During the same period, manpower experts predicted this situation would continue in the foreseeable future. However, when the 60's ended, the employment illusion had been rudely dispelled by frantic reports of a…

  13. Optoelectronic pH Meter: Further Details

    NASA Technical Reports Server (NTRS)

    Jeevarajan, Antony S.; Anderson, Mejody M.; Macatangay, Ariel V.

    2009-01-01

    A collection of documents provides further detailed information about an optoelectronic instrument that measures the pH of an aqueous cell-culture medium to within 0.1 unit in the range from 6.5 to 7.5. The instrument at an earlier stage of development was reported in Optoelectronic Instrument Monitors pH in a Culture Medium (MSC-23107), NASA Tech Briefs, Vol. 28, No. 9 (September 2004), page 4a. To recapitulate: The instrument includes a quartz cuvette through which the medium flows as it is circulated through a bioreactor. The medium contains some phenol red, which is an organic pH-indicator dye. The cuvette sits between a light source and a photodetector. [The light source in the earlier version comprised red (625 nm) and green (558 nm) light-emitting diodes (LEDs); the light source in the present version comprises a single green- (560 nm)-or-red (623 nm) LED.] The red and green are repeatedly flashed in alternation. The responses of the photodiode to the green and red are processed electronically to obtain the ratio between the amounts of green and red light transmitted through the medium. The optical absorbance of the phenol red in the green light varies as a known function of pH. Hence, the pH of the medium can be calculated from the aforesaid ratio.

  14. pH & Rate of Enzymatic Reactions.

    ERIC Educational Resources Information Center

    Clariana, Roy B.

    1991-01-01

    A quantitative and inexpensive way to measure the rate of enzymatic reaction is provided. The effects of different pH levels on the reaction rate of an enzyme from yeast are investigated and the results graphed. Background information, a list of needed materials, directions for preparing solutions, procedure, and results and discussion are…

  15. The Ph.D. Value Proposition

    ERIC Educational Resources Information Center

    Cooper, Kenneth J.

    2012-01-01

    Atlanta University launched its doctor of arts in humanities (DAH) programs almost 40 years ago, and, since the 1988 merger with Clark College, Clark Atlanta University has continued to award the degrees. This fall, for the first time, its students will be able to earn Ph.D.s in humanities instead. In DAH programs around the country, there's been…

  16. Monitoring fetal pH by telemetry

    NASA Technical Reports Server (NTRS)

    Blum, A.; Donahoe, T.; Jhabvala, M. D.; Ryan, W.

    1980-01-01

    Telemetry unit has been developed for possible use in measuring scalp-tissue pH and heart rate of unborn infant. Unit radius data to receiver as much as 50 ft. away. Application exists during hours just prior to childbirth to give warning of problems that might require cesarean delivery.

  17. The pH of Enceladus' ocean

    NASA Astrophysics Data System (ADS)

    Glein, Christopher R.; Baross, John A.; Waite, J. Hunter

    2015-08-01

    Saturn's moon, Enceladus, is a geologically active waterworld. The prevailing paradigm is that there is a subsurface ocean that erupts to the surface, which leads to the formation of a plume of vapor and ice above the south polar region. The chemistry of the ocean is just beginning to be understood, but is of profound geochemical and astrobiological interest. Here, we determine the pH of the ocean using a thermodynamic model of carbonate speciation. Observational data from the Cassini spacecraft are used to make a chemical model of ocean water on Enceladus. The model suggests that Enceladus' ocean is a Na-Cl-CO3 solution with an alkaline pH of ∼11-12. The dominance of aqueous NaCl is a feature that Enceladus' ocean shares with terrestrial seawater, but the ubiquity of dissolved Na2CO3 suggests that soda lakes are more analogous to the Enceladus ocean. The high pH implies that the hydroxide ion should be relatively abundant, while divalent metals should be present at low concentrations owing to buffering by carbonates and phyllosilicates on the ocean floor. Carboxyl groups in dissolved organic species would be negatively charged, while amino groups would exist predominately in the neutral form. Knowledge of the pH improves our understanding of geochemical processes in Enceladus' ocean. The high pH is interpreted to be a key consequence of serpentinization of chondritic rock, as predicted by prior geochemical reaction path models; although degassing of CO2 from the ocean may also play a role depending on the efficiency of mixing processes in the ocean. Serpentinization leads to the generation of H2, a geochemical fuel that can support both abiotic and biological synthesis of organic molecules such as those that have been detected in Enceladus' plume. Serpentinization and H2 generation should have occurred on Enceladus, like on the parent bodies of aqueously altered meteorites; but it is unknown whether these critical processes are still taking place, or if

  18. EMS in the pueblos.

    PubMed

    Vigil, M A

    1994-02-01

    Imagine creating a movie by excerpting scenes from "Dances With Wolves," splicing it with footage from "Code 3" or "Emergency Response" and then flavoring the script with the mystery of a Tony Hillerman novel. A film producer would probably find it quite difficult to choreograph a finished product from such a compilation of material. To hundreds of Native American EMS providers, however, such a movie is played out every day in Indian country. And with this movie come some real-life problems, including trauma, which is the number-one cause of premature death among Native Americans. But a high trauma rate is just one of the challenges facing tribal EMS responders. There's also prolonged response and transport, the problems involved in maintaining the unique culture and standard of care, the challenges of tribal EMS administration and EMS education of Native American students, and the unsure future of Native American EMS. Beyond that, there's the fact that EMS is a s unique to each Indian reservation as are the cultures of the native peoples who reside on these lands. Yet while no two systems are alike, most tribal EMS providers face similar challenges.

  19. 21 CFR 876.1400 - Stomach pH electrode.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Stomach pH electrode. 876.1400 Section 876.1400...) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Diagnostic Devices § 876.1400 Stomach pH electrode. (a) Identification. A stomach pH electrode is a device used to measure intragastric and intraesophageal pH...

  20. 21 CFR 876.1400 - Stomach pH electrode.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Stomach pH electrode. 876.1400 Section 876.1400...) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Diagnostic Devices § 876.1400 Stomach pH electrode. (a) Identification. A stomach pH electrode is a device used to measure intragastric and intraesophageal pH...

  1. 21 CFR 876.1400 - Stomach pH electrode.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Stomach pH electrode. 876.1400 Section 876.1400...) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Diagnostic Devices § 876.1400 Stomach pH electrode. (a) Identification. A stomach pH electrode is a device used to measure intragastric and intraesophageal pH...

  2. 21 CFR 876.1400 - Stomach pH electrode.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Stomach pH electrode. 876.1400 Section 876.1400...) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Diagnostic Devices § 876.1400 Stomach pH electrode. (a) Identification. A stomach pH electrode is a device used to measure intragastric and intraesophageal pH...

  3. PH DEPENDENT TOXICITY OF FIVE METALS TO THREE MARINE ORGANISMS

    EPA Science Inventory

    The pH of natural marine systems is relatively stable; this may explain why metal toxicity changes with pH have not been well documented. However, changes in metal toxicity with pH in marine waters are of concern in toxicity testing. During porewater toxicity testing pH can chang...

  4. 21 CFR 876.1400 - Stomach pH electrode.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Stomach pH electrode. 876.1400 Section 876.1400...) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Diagnostic Devices § 876.1400 Stomach pH electrode. (a) Identification. A stomach pH electrode is a device used to measure intragastric and intraesophageal pH...

  5. What Is a pH Probe Study?

    MedlinePlus

    What is a pH Probe Study ? What is pH a probe study? M easuring the pH in the esophagus helps determine whether or not acid is coming up from the stomach. A pH probe study is usually done in patients where ...

  6. [Measurement of intracellular pH].

    PubMed

    Hanaoka, K; Imai, M; Yoshitomi, K

    1992-09-01

    Since various cellular processes depend on changes in pH, the regulation of intracellular pH (pHi) is important both for the individual cell and for the organism. The mechanisms of the regulation of pHi can be investigated by monitoring pHi. In this report, we discuss the four major techniques available for measuring pHi, which are 1) Distribution of weak acids and bases, 2) pH-sensitive microelectrodes, 3) pH-sensitive dyes, and 4) Nuclear magnetic resonance. Among four techniques, the advantage of the microelectrode approach is that it can monitor membrane potential at the same time and be applied to a single cell. The dye technique is a relative new developing technique, which has lots of advantages. It is easy to use, and is capable of monitoring rapid pHi changes, and being applied to a smaller cell, or a single cell.

  7. Not Your Father's Ph.D.

    ERIC Educational Resources Information Center

    Withrow, Brandon G.

    2008-01-01

    This article describes how the author, a devoted blogger, confronts his fear that his virtual life is damaging his career prospects in academe. As a new Ph.D. in religious studies, the author has every reason to believe he will find a tenure-track job. He has read the numbers and know that, on average, job candidates spend two to five years in…

  8. Complexation Key to a pH Locked Redox Reaction

    ERIC Educational Resources Information Center

    Rizvi, Masood Ahmad; Dangat, Yuvraj; Shams, Tahir; Khan, Khaliquz Zaman

    2016-01-01

    An unfavorable pH can block a feasible electron transfer for a pH dependent redox reaction. In this experiment, a series of potentiometric titrations demonstrate the sequential loss in feasibility of iron(II) dichromate redox reaction over a pH range of 0-4. The pH at which this reaction failed to occur was termed as a pH locked reaction. The…

  9. The Added Value of a PhD in Medicine--PhD Students' Perceptions of Acquired Competences

    ERIC Educational Resources Information Center

    Anttila, Henrika; Lindblom-Ylänne, Sari; Lonka, Kristi; Pyhältö, Kirsi

    2015-01-01

    PhD in the field of medicine is more common than in any other domain. Many medical doctors are driven towards PhD, but also students with other backgrounds (usually MSc) are conducting a PhD in medical schools. Higher education has invested a lot in developing generic and research competences. Still little is known about how PhD students…

  10. The panacea toolbox of a PhD biomedical student.

    PubMed

    Skaik, Younis

    2014-01-01

    Doing a PhD (doctor of philosophy) for the sake of contribution to knowledge should give the student an immense enthusiasm through the PhD period. It is the time in one's life that one spends to "hit the nail on the head" in a specific area and topic of interest. A PhD consists mostly of hard work and tenacity; however, luck and genius might also play a little role. You can pass all PhD phases without having both luck and genius. The PhD student should have pre-PhD and PhD toolboxes, which are "sine quibus non" for getting successfully a PhD degree. In this manuscript, the toolboxes of the PhD student are discussed.

  11. Structural changes induced by acidic pH in human apolipoprotein B-100

    PubMed Central

    Fernández-Higuero, José A.; Benito-Vicente, Asier; Etxebarria, Aitor; Milicua, José Carlos G.; Ostolaza, Helena; Arrondo, José L. R.; Martín, Cesar

    2016-01-01

    Acidification in the endosome causes lipoprotein release by promoting a conformational change in the LDLR allowing its recycling and degradation of LDL. Notwithstanding conformational changes occurring in the LDLR have expanded considerably, structural changes occurring in LDL particles have not been fully explored yet. The objectives of the present work were to study structural changes occurring in apoB100 by infrared spectroscopy (IR) and also LDL size and morphology by dynamic light scattering (DLS) and electron microscopy (EM) at both pH 7.4 and 5.0. We determined by IR that pH acidification from 7.4 to 5.0, resembling that occurring within endosomal environment, induces a huge reversible structural rearrangement of apoB100 that is characterized by a reduction of beta-sheet content in favor of alpha-helix structures. Data obtained from DLS and EM showed no appreciable differences in size and morphology of LDL. These structural changes observed in apoB100, which are likely implied in particle release from lipoprotein receptor, also compromise the apoprotein stability what would facilitate LDL degradation. In conclusion, the obtained results reveal a more dynamic picture of the LDL/LDLR dissociation process than previously perceived and provide new structural insights into LDL/LDLR interactions than can occur at endosomal low-pH milieu. PMID:27824107

  12. Recent Ph.D.s; Honors

    NASA Astrophysics Data System (ADS)

    2005-04-01

    Recent Ph.D.s. Atmospheric Sciences. A study of atmospheric ammonia in coastal ecosystems utilizing relaxed eddy accumulation techniques and ion mobility spectrometry, LaToya Myles, Florida A&M University, December 2004, Advisor: Larry Robinson. Honors. Rana A. Fine has been awarded the 2005 Provost Award for Scholarly Activity, presented by the University of Miami. The award ``recognizes faculty for extraordinary research and scholarly pursuits.'' Charles David Keeling and Lonnie G. Thompson will receive the 2005 Tyler Prize for Environmental Achievement. The prize is given to individuals whose accomplishments in environmental science, policy, energy, and medicine confer great benefit upon mankind.

  13. Intracellular pH in sperm physiology.

    PubMed

    Nishigaki, Takuya; José, Omar; González-Cota, Ana Laura; Romero, Francisco; Treviño, Claudia L; Darszon, Alberto

    2014-08-01

    Intracellular pH (pHi) regulation is essential for cell function. Notably, several unique sperm ion transporters and enzymes whose elimination causes infertility are either pHi dependent or somehow related to pHi regulation. Amongst them are: CatSper, a Ca(2+) channel; Slo3, a K(+) channel; the sperm-specific Na(+)/H(+) exchanger and the soluble adenylyl cyclase. It is thus clear that pHi regulation is of the utmost importance for sperm physiology. This review briefly summarizes the key components involved in pHi regulation, their characteristics and participation in fundamental sperm functions such as motility, maturation and the acrosome reaction.

  14. Nanomechanical DNA Origami pH Sensors

    PubMed Central

    Kuzuya, Akinori; Watanabe, Ryosuke; Yamanaka, Yusei; Tamaki, Takuya; Kaino, Masafumi; Ohya, Yuichi

    2014-01-01

    Single-molecule pH sensors have been developed by utilizing molecular imaging of pH-responsive shape transition of nanomechanical DNA origami devices with atomic force microscopy (AFM). Short DNA fragments that can form i-motifs were introduced to nanomechanical DNA origami devices with pliers-like shape (DNA Origami Pliers), which consist of two levers of 170-nm long and 20-nm wide connected at a Holliday-junction fulcrum. DNA Origami Pliers can be observed as in three distinct forms; cross, antiparallel and parallel forms, and cross form is the dominant species when no additional interaction is introduced to DNA Origami Pliers. Introduction of nine pairs of 12-mer sequence (5′-AACCCCAACCCC-3′), which dimerize into i-motif quadruplexes upon protonation of cytosine, drives transition of DNA Origami Pliers from open cross form into closed parallel form under acidic conditions. Such pH-dependent transition was clearly imaged on mica in molecular resolution by AFM, showing potential application of the system to single-molecular pH sensors. PMID:25325338

  15. The pH of Mars

    NASA Technical Reports Server (NTRS)

    Plumb, R. C.; Bishop, J. L.; Edwards, J. O.

    1993-01-01

    The Viking labeled release (LR) experiments provided data that can be used to determine the acid-base characteristics of the regolith. Constraints on the acid-base properties and redox potentials of the Martian surface material would provide additional information for determining what reactions are possible and defining formation conditions for the regolith. Calculations devised to determine the pH of Mars must include the amount of soluble acid species or base species present in the LR regolith sample and the solubility product of the carbonate with the limiting solubility. This analysis shows that CaCO3, either as calcite or aragonite, has the correct K(sub sp) to have produced the Viking LR successive injection reabsorption effects. Thus CaCO3 or another MeCO3 with very similar solubility characteristics must have been present on Mars. A small amount of soluble acid, but no more than 4 micro-mol per sample, could also have been present. It is concluded that the pH of the regolith is 7.2 +/- 0.1.

  16. Constant pH simulations of pH responsive polymers

    NASA Astrophysics Data System (ADS)

    Sharma, Arjun; Smith, J. D.; Walters, Keisha B.; Rick, Steven W.

    2016-12-01

    Polyacidic polymers can change structure over a narrow range of pH in a competition between the hydrophobic effect, which favors a compact state, and electrostatic repulsion, which favors an extended state. Constant pH molecular dynamics computer simulations of poly(methacrylic acid) reveal that there are two types of structural changes, one local and one global, which make up the overall response. The local structural response depends on the tacticity of the polymer and leads to different cooperative effects for polymers with different stereochemistries, demonstrating both positive and negative cooperativities.

  17. Organelle pH in the Arabidopsis endomembrane system.

    PubMed

    Shen, Jinbo; Zeng, Yonglun; Zhuang, Xiaohong; Sun, Lei; Yao, Xiaoqiang; Pimpl, Peter; Jiang, Liwen

    2013-09-01

    The pH of intracellular compartments is essential for the viability of cells. Despite its relevance, little is known about the pH of these compartments. To measure pH in vivo, we have first generated two pH sensors by combining the improved-solubility feature of solubility-modified green fluorescent protein (GFP) (smGFP) with the pH-sensing capability of the pHluorins and codon optimized for expression in Arabidopsis. PEpHluorin (plant-solubility-modified ecliptic pHluorin) gradually loses fluorescence as pH is lowered with fluorescence vanishing at pH 6.2 and PRpHluorin (plant-solubility-modified ratiomatric pHluorin), a dual-excitation sensor, allowing for precise measurements. Compartment-specific sensors were generated by further fusing specific sorting signals to PEpHluorin and PRpHluorin. Our results show that the pH of cytosol and nucleus is similar (pH 7.3 and 7.2), while peroxisomes, mitochondrial matrix, and plastidial stroma have alkaline pH. Compartments of the secretory pathway reveal a gradual acidification, spanning from pH 7.1 in the endoplasmic reticulum (ER) to pH 5.2 in the vacuole. Surprisingly, pH in the trans-Golgi network (TGN) and multivesicular body (MVB) is, with pH 6.3 and 6.2, quite similar. The inhibition of vacuolar-type H(+)-ATPase (V-ATPase) with concanamycin A (ConcA) caused drastic increase in pH in TGN and vacuole. Overall, the PEpHluorin and PRpHluorin are excellent pH sensors for visualization and quantification of pH in vivo, respectively.

  18. EMS in Mauritius.

    PubMed

    Ramalanjaona, Georges; Brogan, Gerald X

    2009-02-01

    Mauritius lies in the southwest Indian Ocean about 1250 miles from the African coast and 500 miles from Madagascar. Mauritius (estimated population 1,230,602) became independent from the United Kingdom in 1968 and has one of the highest GDP per capita in Africa. Within Mauritius there is a well established EMS system with a single 999 national dispatch system. Ambulances are either publicly or privately owned. Public ambulances are run by the Government (SAMU). Megacare is a private subscriber only ambulance service. The Government has recently invested in new technology such as telemedicine to further enhance the role of EMS on the island. This article describes the current state of EMS in Mauritius and depicts its development in the context of Government effort to decentralise and modernise the healthcare system.

  19. Ian Douglass Coulter, PhD

    PubMed Central

    Brown, Douglas M

    2004-01-01

    This paper focuses on Dr. Ian Coulter’s accomplishments from the time he became Executive Vice-President of CMCC in 1981, until he ended his presidency with a year’s administrative leave in 1990. Annual planning initiatives, pedagogy, scholarship, conflicts, and the quest for university affiliation are discussed as well as his legacy to the College and the chiropractic profession. The term “adventurous” was first attributed to Coulter by Oswald Hall, PhD, Professor Emeritus, University of Toronto who had worked closely with Coulter in a major investigation of the chiropractic profession from 1976 to 1979. Throughout this article the author tries to capture the spirit of daring, innovation and intellect that permeated Coulter’s presidency, enthralling his advocates and confounding his detractors. PMID:17549218

  20. Intracellular pH in Sperm Physiology

    PubMed Central

    Nishigaki, Takuya; José, Omar; González-Cota, Ana Laura; Romero, Francisco; Treviño, Claudia L.; Darszon, Alberto

    2014-01-01

    Intracellular pH (pHi) regulation is essential for cell function. Notably, several unique sperm ion transporters and enzymes whose elimination causes infertility are either pHi dependent or somehow related to pHi regulation. Amongst them are: CatSper, a Ca2+ channel; Slo3, a K+ channel; the sperm-specific Na+/H+ exchanger and the soluble adenylyl cyclase. It is thus clear that pHi regulation is of the utmost importance for sperm physiology. This review briefly summarizes the key components involved in pHi regulation, their characteristics and participation in fundamental sperm functions such as motility, maturation and the acrosome reaction. PMID:24887564

  1. Barrett's oesophagus: pH profile.

    PubMed

    Gillen, P; Keeling, P; Byrne, P J; Hennessy, T P

    1987-09-01

    Twenty-four patients with a columnar-lined (Barrett's) oesophagus underwent oesophageal manometry and 24 h ambulatory oesophageal pH monitoring. The results were compared with 25 patients with oesophagitis studied in the same fashion. No significant difference in lower oesophageal sphincter pressure was demonstrated between the two groups. The Barrett's patients demonstrated significantly greater acid exposure in the distal oesophagus than oesophagitis patients. Clearance or refluxed acid was poorer in Barrett's patients than oesophagitis patients. Twelve of the Barrett's patients presented with complications of the condition, i.e. ulceration or stricture. No significant difference in acid exposure was demonstrated between Barrett's patients with or without complications. These results suggest that patients with columnar-lined (Barrett's) oesophagus have greater acid exposure than patients with oesophagitis. The development of complications of a Barrett's oesophagus may not be dependent on acid reflux alone.

  2. Acid Rain, pH & Acidity: A Common Misinterpretation.

    ERIC Educational Resources Information Center

    Clark, David B.; Thompson, Ronald E.

    1989-01-01

    Illustrates the basis for misleading statements about the relationship between pH and acid content in acid rain. Explains why pH cannot be used as a measure of acidity for rain or any other solution. Suggests that teachers present acidity and pH as two separate and distinct concepts. (RT)

  3. Steel slag raises pH of greenhouse substrates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dolomitic lime (DL) is the primary liming agent used for increasing pH in peatmoss-based substrates. Steel slag (SS) is a byproduct of the steel manufacturing industry that has been used to elevate field soil pH. The objective of this research was to determine the pH response of a peatmoss-based g...

  4. High temperature pH measurements using novel pH electrodes. Final report

    SciTech Connect

    Macdonald, D.D.; Song, H.; Hettiarachchi, S.

    1995-12-01

    Researchers used three pH sensors: (1) a yttria-stabilized zirconia, (2) tungsten/tungsten oxide, and (3) platinum hydrogen electrodes to measure the pH in concentrated solutions heated to temperatures from 125-300 C in autoclaves. The studies indicated measurements of pH for solutions containing sodium hydroxide, sodium sulfate, sodium chloride, boric acid, ferrous sulfate, nickel sulfate, and chromous sulfate in various compositions. The solution composition and pH was then calculated by MULTEQ at the experimental conditions. These calculations compared well with the experimental measurements for binary and quaternary systems at temperatures to 300 C and concentrations to 1 molal. The agreement was also excellent for the metal sulfate systems but was poor for chromous sulfate. The agreement for boric acid solutions was adequate for low concentrations of boric acid but was poor for concentrated borate solutions where polyborate ions likely exist. It is not known whether the lack of agreement under these conditions is due to deficiencies in MULTEQ or the experimental measurements.

  5. Understanding Non-Traditional PhD Students Habitus--Implications for PhD Programmes

    ERIC Educational Resources Information Center

    Naidoo, Devika

    2015-01-01

    Against the background of vast changes in doctoral education and the emergence of non-traditional doctoral programmes, this paper investigates the habitus of non-traditional PhD students at a South African university. Bourdieu's conceptual tool of habitus informed the study. In-depth and open-ended interviews were conducted with 10 non-traditional…

  6. Comparison of Rumen Fluid pH by Continuous Telemetry System and Bench pH Meter in Sheep with Different Ranges of Ruminal pH

    PubMed Central

    Reis, Leonardo F.; Minervino, Antonio H. H.; Araújo, Carolina A. S. C.; Sousa, Rejane S.; Oliveira, Francisco L. C.; Rodrigues, Frederico A. M. L.; Meira-Júnior, Enoch B. S.; Barrêto-Júnior, Raimundo A.; Mori, Clara S.; Ortolani, Enrico L.

    2014-01-01

    We aimed to compare the measurements of sheep ruminal pH using a continuous telemetry system or a bench pH meter using sheep with different degrees of ruminal pH. Ruminal lactic acidosis was induced in nine adult crossbred Santa Ines sheep by the administration of 15 g of sucrose per kg/BW. Samples of rumen fluid were collected at the baseline, before the induction of acidosis (T0) and at six, 12, 18, 24, 48, and 72 hours after the induction for pH measurement using a bench pH meter. During this 72-hour period, all animals had electrodes for the continuous measurement of pH. The results were compared using the Bland-Altman analysis of agreement, Pearson coefficients of correlation and determination, and paired analysis of variance with Student's t-test. The measurement methods presented a strong correlation (r = 0.94, P < 0.05) but the rumen pH that was measured continuously using a telemetry system resulted in lower values than the bench pH meter (overall mean of 5.38 and 5.48, resp., P = 0.0001). The telemetry system was able to detect smaller changes in rumen fluid pH and was more accurate in diagnosing both subacute ruminal lactic acidosis and acute ruminal lactic acidosis in sheep. PMID:24967422

  7. Proton Transport and pH Control in Fungi.

    PubMed

    Kane, Patricia M

    2016-01-01

    Despite diverse and changing extracellular environments, fungi maintain a relatively constant cytosolic pH and numerous organelles of distinct lumenal pH. Key players in fungal pH control are V-ATPases and the P-type proton pump Pma1. These two proton pumps act in concert with a large array of other transporters and are highly regulated. The activities of Pma1 and the V-ATPase are coordinated under some conditions, suggesting that pH in the cytosol and organelles is not controlled independently. Genomic studies, particularly in the highly tractable S. cerevisiae, are beginning to provide a systems-level view of pH control, including transcriptional responses to acid or alkaline ambient pH and definition of the full set of regulators required to maintain pH homeostasis. Genetically encoded pH sensors have provided new insights into localized mechanisms of pH control, as well as highlighting the dynamic nature of pH responses to the extracellular environment. Recent studies indicate that cellular pH plays a genuine signaling role that connects nutrient availability and growth rate through a number of mechanisms. Many of the pH control mechanisms found in S. cerevisiae are shared with other fungi, with adaptations for their individual physiological contexts. Fungi deploy certain proton transport and pH control mechanisms not shared with other eukaryotes; these regulators of cellular pH are potential antifungal targets. This review describes current and emerging knowledge proton transport and pH control mechanisms in S. cerevisiae and briefly discusses how these mechanisms vary among fungi.

  8. pH distributions in spontaneous and isotransplanted rat tumours.

    PubMed Central

    Kallinowski, F.; Vaupel, P.

    1988-01-01

    Spontaneous mammary tumours of the rat with various degrees of malignancy exhibit similar tissue pH distributions. The mean pH (+/- s.d.) of dysplasia is 7.05 +/- 0.20. In benign tumours the mean pH is 6.95 +/- 0.19 and in malignant tumours it is 6.94 +/- 0.19. In contrast, tumours with the same degree of malignancy but different histologies show different pH distributions. Benign tumours with a higher percentage of fibrous tissue exhibit less acidic pH values than those with larger portions of epithelial cells (delta pH = 0.38 pH units). The pH distribution in the benign tumours is independent of the tumour wet weight up to stages of very advanced growth. In the malignant tumours, a trend towards more acidic pH values is observed as the tumour mass enlarges. However, in tissue areas within a malignant tumour with gross, long-established necrosis the pH distribution is shifted towards more alkaline pH values. The pH distributions in spontaneous rat tumours are not significantly different from those obtained in isotransplanted Yoshida sarcomas (6.87 +/- 0.21). In the Yoshida sarcomas, mean pH values do not correlate with tumour size. However, a pH gradient from the rim to the centre of the tumours is found which coincides with the development of small, disseminated necroses in the tumour centre. It is concluded that pathology-related variations of tumour pH may be more important than the mode of tumour origin or the degree of malignancy. PMID:3179183

  9. PhD Students' Work Conditions and Study Environment in University- and Industry-Based PhD Programmes

    ERIC Educational Resources Information Center

    Kolmos, A.; Kofoed, L. B.; Du, X. Y.

    2008-01-01

    During the last 10 years, new models of funding and training PhD students have been established in Denmark in order to integrate industry into the entire PhD education. Several programmes have been conducted where it is possible to co-finance PhD scholarships or to become an employee as an industrial PhD in a company. An important question is what…

  10. The Role of pH Regulation in Cancer Progression.

    PubMed

    McIntyre, Alan; Harris, Adrian L

    Frequently observed phenotypes of tumours include high metabolic activity, hypoxia and poor perfusion; these act to produce an acidic microenvironment. Cellular function depends on pH homoeostasis, and thus, tumours become dependent on pH regulatory mechanisms. Many of the proteins involved in pH regulation are highly expressed in tumours, and their expression is often of prognostic significance. The more acidic tumour microenvironment also has important implications with regard to chemotherapeutic and radiotherapeutic interventions. In addition, we review pH-sensing mechanisms, the role of pH regulation in tumour phenotype and the use of pH regulatory mechanisms as therapeutic targets.

  11. Continuous intra-arterial pH measurement.

    PubMed

    Oeseburg, B; Kwant, G; Schut, J K; Veenstra, J

    1980-07-01

    A flexible glass electrode catheter with a diameter of 3 mm has been developed for pH measurement in the arterial system of dogs. In combination with a galvanically isolated amplifier, an undisturbed pH signal could be obtained from the aorta. The system was fast enough to truly record pH changes synchronous with respiration and was shown to be insensitive to variations in blood flow velocity. Good agreement was found between pH catheter readings nd pH values of simultaneously taken arterial samples as measured with a conventional capillary glass electrode.

  12. Time course of pH change in plant epidermis using microscopic pH imaging system

    NASA Astrophysics Data System (ADS)

    Dan, Risako; Shimizu, Megumi; Kazama, Haruko; Sakaue, Hirotaka

    2010-11-01

    We established a microscopic pH imaging system to track the time course of pH change in plant epidermis in vivo. In the previous research, we have found out that anthocyanin containing cells have higher pH. However, it was not clear whether the anthocyanin increased the pH or anthocyanin was synthesized result from the higher pH. Therefore, we further investigated the relationship between anthocyanin and pH change. To track the time course of pH change in plant epidermis, we established a system using luminescent imaging technique. We used HPTS (8-Hydroxypyrene-1,3,6-Trisulfonate) as pH indicator and applied excitation ratio imaging method. Luminescent image was converted to a pH distribution by obtained in vitro calibration using known pH solution. Cellular level observation was enabled by merging microscopic color picture of the same region to the pH change image. The established system was applied to epidermal cells of red-tip leaf lettuce, Lactuca Sativa L. and the time course was tracked in the growth process. We would discuss about the relationship between anthocyanin and pH change in plant epidermis.

  13. Accurate transport properties for O(3P)-H and O(3P)-H2

    NASA Astrophysics Data System (ADS)

    Dagdigian, Paul J.; Kłos, Jacek; Warehime, Mick; Alexander, Millard H.

    2016-10-01

    Transport properties for collisions of oxygen atoms with hydrogen atoms and hydrogen molecules have been computed by means of time-independent quantum scattering calculations. For the O(3P)-H(2S) interaction, potential energy curves for the four OH electronic states emanating from this asymptote were computed by the internally-contracted multi-reference configuration interaction method, and the R-dependent spin-orbit matrix elements were taken from Parlant and Yarkony [J. Chem. Phys. 110, 363 (1999)]. For the O(3P)-H2 interaction, diabatic potential energy surfaces were derived from internally contracted multi-reference configuration interaction calculations. Transport properties were computed for these two collision pairs and compared with those obtained with the conventional approach that employs isotropic Lennard-Jones (12-6) potentials.

  14. To PhET or Not To PhET: That Is the Question

    NASA Astrophysics Data System (ADS)

    Casao, Robert

    2008-10-01

    The investigation examined use of a Physics Education Technology (PhET) simulation versus a hands-on lab activity on student's conceptual understanding of physics content. Topics of study included vectors, projectile motion, direct current (DC) circuits, and the photoelectric effect. Participants consisted of high school juniors and seniors enrolled in a physics course. Assessment instruments consisted of questions taken from the Vector Evaluation Test, the Electric Circuits Concept Evaluation test, textbook test banks, or written to address concepts under evaluation. Data collection consisted of a pre-test score, a post-test score, and a gain score. The conceptual understanding of the experimental and the control groups did not significantly differ for vectors and DC circuits. The conceptual understanding of the experimental and control groups did significantly differ for projectile motion. The results indicated a conceptual gain for students using the photoelectric effect simulation. Student attitudes towards the PhET simulations were positive.

  15. Low pH alkaline chemical formulations

    SciTech Connect

    French, T.R.; Peru, D.A.; Thornton, S.D.

    1989-01-01

    This report describes the development of a surfactant-enhanced alkaline flooding system that is applicable to specific reservoir conditions in Wilmington (California) field. The cost of the chemicals for an ASP (alkali/surfactant/polymer) flood is calculated to be $3.90/bbl of oil produced, with 78% of that cost attributable to polymer. This research included phase behavior tests, oil displacement tests, mineral dissolution tests, and adsorption measurements. It was discovered that consumption of low pH alkalis is low enough in the Wilmington field to be acceptable. In addition, alkali dramatically reduced surfactant adsorption and precipitation. A mixture of NaHCO3 and Na2CO3 was recommended for use as a preflush and in the ASP formulation. Research was also conducted on the synergistic effect that occurs when a mixture of alkali and synthetic surfactant contacts crude oil. It appears that very low IFT is predominantly a result of the activation of the natural surfactants present in the Wilmington oil, and the sustained low IFT is primarily the result of the synthetic surfactant. It also appears that removal of acids from the crude oil by the alkali renders the oil more interfacially reactive to synthetic surfactant. These phenomena help to explain the synergism that results from combining alkali and synthetic surfactant into a single oil recovery formulation. 19 refs., 24 figs., 10 tabs.

  16. Combined M.D./Ph.D. and Ph.D. Training Program in Breast Cancer Prevention

    DTIC Science & Technology

    2005-07-01

    of trainees, and the development of courses for the program. In the sixth year, we recruited Ms. Anne Miermont and Mr. Mark Markowski . Ms. Miermont...Baltimore County. Mr. Markowski , an MD/PhD student received his BS in Biochemistry and Mathematics from Georgetown University. Ms. Miermont is...currently working in the lab of her Thesis Mentor, Dr. Priscilla Furth. Mr. Markowski is currently working in the lab of Thesis Mentor Dr. Edward Gelmann

  17. Italia-Netherland PhD Program: the I.O. PhD Research Program.

    PubMed

    Bellissima, Valentina; Borghesi, Alessandro; Bozzetti, Valentina; Dessì, Angelica; Fabiano, Adele; Risso, Francesco M; Salvo, Vincenzo; Satriano, Angela; Silvagni, Davide; Varrica, Alessandro; van Bel, Frank; Visser, Gerard H A; Vles, Hans Js; Zimmermann, Luc J I; Gavilanes, Antonio D W; Gazzolo, Diego

    2011-10-01

    In the framework of long-term scientific collaboration among the founder members coming from Holland and Italy there was a growing consensus to activate a philosophical doctorate (PhD) program, involving young Italian researchers in the field of perinatal medicine, neonatology and pediatrics. The aims were to promote excellence in research, offering to young Italian physicians the opportunity to maturate an International research experience leading to PhD degree, and to promote human and technological improvement energies in perinatal, neonatal and pediatrics research. Thus, an official collaboration among the Dutch Universities from Maastricht and Utrecht and the Italian Children's Hospital from Alessandria, has been activated on March 1st 2010, finalized to the PhD program. The experimental phase included the selection of projects and relative candidates after an interview-selection focusing on their scientific attitudes and the availability on their research projects. Candidates' selection started on May 2010 and on September 29th ten projects and candidates have been approved by the scientific commission. Research topics included: perinatal asphyxia, aging and the origin of adulthood neurodegenerative disease, neuroprotective strategies, biochemical pulmonology, intrauterine growth retardation and perinatal teratology. To date, all projects have been approved by local Ethics Committee from the University/Hospital of origin of the candidates. Five manuscripts have been published and/or submitted to international Journals regarding pneumology, perinatal asphyxia and teratology, whilst about 60-70% of data regarding clinical studies have already been collected.

  18. In vitro synthesis and purification of PhIP-deoxyguanosine and PhIP-DNA oligomer covalent complexes

    SciTech Connect

    Freeman, J.

    1994-12-01

    2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a heterocyclic amine compound formed when meats are cooked at high temperatures. PhIP damages DNA by forming covalent complexes with DNA carcinogen. In an effort to understand how the binding of PhIP to DNA may cause cancer, it is important to characterize the structures of PhIP-damaged DNA molecules. Our HPLC data support fluorescence and {sup 32}P Post-labeling studies which indicate the formation of several species of 2{prime}deoxyguanosine-(dG) or oligodeoxynucleotide-PhIP adducts. The reaction of PhIP with dG resulted in a reddish precipitate that was likely the major adduct, N-(deoxyguanosin-8-yl)-PhIP (dG-C8-PhIP) adduct, with a more polar adduct fraction remaining in the supernatant. Reversed-phase HPLC analysis of the adducts in the supernatant revealed the existence of species of much shorter retention times than the dG-C8-PhIP adduct, confirming that these species are more polar than dG-C8-PhIP. At least four adducts were formed in the reaction of PhIP with DNA oligomer. HPLC analysis of the PhIP-DNA oligomer supernatant after butanol extractions revealed four unresolved peaks which spectra had maximum wavelengths between 340 and 360 nm. Though adduct peaks were not completely resolved, there was {approximately}3 minutes interval between the DNA oligomer peak and the adduct peaks. Furthermore, fluorescence emission data of the DNA oligomer-PhIP adduct solution show heterogeneous binding. The more polar PhIP adducts were fraction-collected and their structures will be solved by nuclear magnetic resonance or x-ray crystallography.

  19. Dipstick Spot urine pH does not accurately represent 24 hour urine PH measured by an electrode

    PubMed Central

    Omar, Mohamed; Sarkissian, Carl; Jianbo, Li; Calle, Juan; Monga, Manoj

    2016-01-01

    ABSTRACT Objectives To determine whether spot urine pH measured by dipstick is an accurate representation of 24 hours urine pH measured by an electrode. Materials and Methods We retrospectively reviewed urine pH results of patients who presented to the urology stone clinic. For each patient we recorded the most recent pH result measured by dipstick from a spot urine sample that preceded the result of a 24-hour urine pH measured by the use of a pH electrode. Patients were excluded if there was a change in medications or dietary recommendations or if the two samples were more than 4 months apart. A difference of more than 0.5 pH was considered an inaccurate result. Results A total 600 patients were retrospectively reviewed for the pH results. The mean difference in pH between spot urine value and the 24 hours collection values was 0.52±0.45 pH. Higher pH was associated with lower accuracy (p<0.001). The accuracy of spot urine samples to predict 24-hour pH values of <5.5 was 68.9%, 68.2% for 5.5 to 6.5 and 35% for >6.5. Samples taken more than 75 days apart had only 49% the accuracy of more recent samples (p<0.002). The overall accuracy is lower than 80% (p<0.001). Influence of diurnal variation was not significant (p=0.588). Conclusions Spot urine pH by dipstick is not an accurate method for evaluation of the patients with urolithiasis. Patients with alkaline urine are more prone to error with reliance on spot urine pH. PMID:27286119

  20. The EM Earthquake Precursor

    NASA Astrophysics Data System (ADS)

    Jones, K. B., II; Saxton, P. T.

    2013-12-01

    Many attempts have been made to determine a sound forecasting method regarding earthquakes and warn the public in turn. Presently, the animal kingdom leads the precursor list alluding to a transmission related source. By applying the animal-based model to an electromagnetic (EM) wave model, various hypotheses were formed, but the most interesting one required the use of a magnetometer with a differing design and geometry. To date, numerous, high-end magnetometers have been in use in close proximity to fault zones for potential earthquake forecasting; however, something is still amiss. The problem still resides with what exactly is forecastable and the investigating direction of EM. After the 1989 Loma Prieta Earthquake, American earthquake investigators predetermined magnetometer use and a minimum earthquake magnitude necessary for EM detection. This action was set in motion, due to the extensive damage incurred and public outrage concerning earthquake forecasting; however, the magnetometers employed, grounded or buried, are completely subject to static and electric fields and have yet to correlate to an identifiable precursor. Secondly, there is neither a networked array for finding any epicentral locations, nor have there been any attempts to find even one. This methodology needs dismissal, because it is overly complicated, subject to continuous change, and provides no response time. As for the minimum magnitude threshold, which was set at M5, this is simply higher than what modern technological advances have gained. Detection can now be achieved at approximately M1, which greatly improves forecasting chances. A propagating precursor has now been detected in both the field and laboratory. Field antenna testing conducted outside the NE Texas town of Timpson in February, 2013, detected three strong EM sources along with numerous weaker signals. The antenna had mobility, and observations were noted for recurrence, duration, and frequency response. Next, two

  1. Cell wall pH and auxin transport velocity

    NASA Technical Reports Server (NTRS)

    Hasenstein, K. H.; Rayle, D.

    1984-01-01

    According to the chemiosmotic polar diffusion hypothesis, auxin pulse velocity and basal secretion should increase with decreasing cell wall pH. Experiments were designed to test this prediction. Avena coleoptile sections were preincubated in either fusicoccin (FC), cycloheximide, pH 4.0, or pH 8.0 buffer and subsequently their polar transport capacities were determined. Relative to controls, FC enhanced auxin (IAA) uptake while CHI and pH 8.0 buffer reduced IAA uptake. Nevertheless, FC reduced IAA pulse velocity while cycloheximide increased velocity. Additional experiments showed that delivery of auxin to receivers is enhanced by increased receiver pH. This phenomenon was overcome by a pretreatment of the tissue with IAA. Our data suggest that while acidic wall pH values facilitate cellular IAA uptake, they do not enhance pulse velocity or basal secretion. These findings are inconsistent with the chemiosmotic hypothesis for auxin transport.

  2. pH measurement of low-conductivity waters

    USGS Publications Warehouse

    Busenberg, Eurybiades; Plummer, L.N.

    1987-01-01

    pH is an important and commonly measured parameter of precipitation and other natural waters. The various sources of errors in pH measurement were analyzed and procedures for improving the accuracy and precision of pH measurements in natural waters with conductivities of < 100 uS/cm at 25 C are suggested. Detailed procedures are given for the preparation of dilute sulfuric acid standards to evaluate the performance of pH electrodes in low conductivity waters. A daily check of the pH of dilute sulfuric acid standards and deionized water saturated with a gas mixture of low carbon dioxide at partial pressure (air) prior to the measurement of the pH of low conductivity waters is suggested. (Author 's abstract)

  3. EMS & the DEA.

    PubMed

    Beeson, Jeff; Ayres, Chris

    2010-01-01

    It's clear that EMS medical directors and management staff must be vigilant in their oversight of implementation, administration and monitoring of controlled substances within their agencies to best serve the public and avoid running afoul of investigation and incurring significant penalties. Those potentially affected by the need for individual registrations of both emergency vehicles and central inventory systems should carefully monitor upcoming developments in the interpretation od DEA regulations.

  4. Chapter A6. Section 6.4. pH

    USGS Publications Warehouse

    Wilde, Franceska D.; Busenberg, Eurybiades; Radtke, Dean B.

    2006-01-01

    Measurement of pH is critical to the understanding of the viability and vulnerability of environmental waters and is considered a master variable in determining the aqueous geochemistry of an aqueous system. pH is a measure that represents the hydrogen-ion concentration (activity) of a solution. This section of the National Field Manual (NFM) describes U.S. Geological Survey (USGS) guidance and protocols for measurement of pH in ground and surface waters.

  5. Ratiometric Imaging of Extracellular pH in Dental Biofilms.

    PubMed

    Schlafer, Sebastian; Dige, Irene

    2016-03-09

    The pH in bacterial biofilms on teeth is of central importance for dental caries, a disease with a high worldwide prevalence. Nutrients and metabolites are not distributed evenly in dental biofilms. A complex interplay of sorption to and reaction with organic matter in the biofilm reduces the diffusion paths of solutes and creates steep gradients of reactive molecules, including organic acids, across the biofilm. Quantitative fluorescent microscopic methods, such as fluorescence life time imaging or pH ratiometry, can be employed to visualize pH in different microenvironments of dental biofilms. pH ratiometry exploits a pH-dependent shift in the fluorescent emission of pH-sensitive dyes. Calculation of the emission ratio at two different wavelengths allows determining local pH in microscopic images, irrespective of the concentration of the dye. Contrary to microelectrodes the technique allows monitoring both vertical and horizontal pH gradients in real-time without mechanically disturbing the biofilm. However, care must be taken to differentiate accurately between extra- and intracellular compartments of the biofilm. Here, the ratiometric dye, seminaphthorhodafluor-4F 5-(and-6) carboxylic acid (C-SNARF-4) is employed to monitor extracellular pH in in vivo grown dental biofilms of unknown species composition. Upon exposure to glucose the dye is up-concentrated inside all bacterial cells in the biofilms; it is thus used both as a universal bacterial stain and as a marker of extracellular pH. After confocal microscopic image acquisition, the bacterial biomass is removed from all pictures using digital image analysis software, which permits to exclusively calculate extracellular pH. pH ratiometry with the ratiometric dye is well-suited to study extracellular pH in thin biofilms of up to 75 µm thickness, but is limited to the pH range between 4.5 and 7.0.

  6. Quantum dot photoluminescence lifetime-based pH nanosensor.

    PubMed

    Ruedas-Rama, Maria J; Orte, Angel; Hall, Elizabeth A H; Alvarez-Pez, Jose M; Talavera, Eva M

    2011-03-14

    The first CdSe/ZnS quantum dot photoluminescence lifetime-based pH nanosensor has been developed. The average lifetime of mercaptopropionic acid-capped QD nanosensors showed a linear response in the pH range of 5.2-6.9. These nanosensors have been satisfactorily applied for pH estimation in simulated intracellular media, with high sensitivity and high selectivity toward most of the intracellular components.

  7. Nanosensor aided photoacoustic measurement of pH in vivo

    NASA Astrophysics Data System (ADS)

    Ray, Aniruddha; Yoon, Hyung Ki; Kopelman, Raoul; Wang, Xueding

    2013-03-01

    pH plays a critical role in many aspects of cell and tissues physiology. Lower pH is also a typical characteristic of arthritic joints and tumor tissues. These pH anomalies are also exploited in different drug delivery mechanisms. Here we present, a new method of pH sensing in vivo using spectroscopic photoacoustic measurements facilitated by pH sensitive nanosensors. The nanosensors consist of Seminaphtharhodafluor (SNARF), a pH sensitive dye, encapsulated in a specially designed polyacrylamide hydrogel matrix with a hydrophobic core. The photoacoustic intensity ratio between the excitation wavelengths of 585nm and 565nm increases in the pH range from 6.0 to 8.0 and is used to determine the pH of the local environment. These nanosensors are biodegradable, biocompatible, have a long plasma lifetime and can be targeted to any type of cells or tissues by surface modification using proper targeting moieties. The encapsulation of the dye prevents the interaction of the dye with proteins in plasma and also reduces the dye degradation. The SNARF dye in its free form loses 90% of its absorbance in presence of albumin, a protein found in abundance in plasma, and this has severely limited its adaptation to in vivo environments. In comparison, the SNARF nanosensors lose only 16% of their absorbance in the same environment. We employ these nanosensors to demonstrate the feasibility of pH sensing in vivo through photoacoustic measurements on a rat joint model.

  8. pH inactivation of phosphofructokinase arrests postmortem glycolysis.

    PubMed

    England, Eric M; Matarneh, Sulaiman K; Scheffler, Tracy L; Wachet, Céline; Gerrard, David E

    2014-12-01

    Fresh meat quality development is influenced by pH decline that results from muscle glycolyzing energy substrates postmortem. The exact reason why glycolysis stops in the presence of residual glycogen remains unclear. We hypothesized that a critical glycolytic enzyme loses activity near the ultimate pH of meat. Porcine longissimus muscle samples were subjected to an in vitro system that mimics postmortem anaerobic metabolism at buffered pH values (7.0, 6.5, 6.0, 5.5 or 5.0). At pH7.0, 6.5, and 6.0, glycogenolysis and glycolysis proceeded normally while pH5.5 stopped lactate formation. Additional experimentation indicated that phosphofructokinase lost activity at pH5.5 while all other glycolytic enzymes remained active. A similar inactivation of phosphofructokinase was observed when using chicken and beef muscle. Elevated temperature hastened pH decline and phosphofructokinase activity loss. Thus, pH inactivates phosphofructokinase and arrests postmortem glycolysis, which may explain the similar ultimate pH across meat of different species.

  9. Cytoplasmic pH and human erythrocyte shape.

    PubMed Central

    Gedde, M M; Davis, D K; Huestis, W H

    1997-01-01

    Altered external pH transforms human erythrocytes from discocytes to stomatocytes (low pH) or echinocytes (high pH). The mechanism of this transformation is unknown. The preceding companion study (Gedde and Huestis) demonstrated that these shape changes are not mediated by changes in membrane potential, as has been reported. The aim of this study was to identify the physiological properties that mediate this shape change. Red cells were placed in a wide range of physiological states by manipulation of buffer pH, chloride concentration, and osmolality. Morphology and four potential predictor properties (cell pH, membrane potential, cell water, and cell chloride concentration) were assayed. Analysis of the data set by stratification and nonlinear multivariate modeling showed that change in neither cell water nor cell chloride altered the morphology of normal pH cells. In contrast, change in cell pH caused shape change in normal-range membrane potential and cell water cells. The results show that change in cytoplasmic pH is both necessary and sufficient for the shape changes of human erythrocytes equilibrated in altered pH environments. PMID:9138569

  10. Field measurement of alkalinity and pH

    USGS Publications Warehouse

    Barnes, Ivan

    1964-01-01

    The behavior of electrometric pH equipment under field conditions departs from the behavior predicted from Nernst's law. The response is a linear function of pH, and hence measured pH values may be corrected to true pH if the instrument is calibrated with two reference solutions for each measurement. Alkalinity titrations may also be made in terms of true pH. Standard methods, such as colorimetric titrations, were rejected as unreliable or too cumbersome for rapid field use. The true pH of the end point of the alkalinity titration as a function of temperature, ionic strength, and total alkalinity has been calculated. Total alkalinity in potable waters is the most important factor influencing the end point pH, which varies from 5.38 (0 ? C, 5 ppm (parts per million) HC0a-) to 4.32 (300 ppm HC0a-,35 ? C), for the ranges of variables considered. With proper precautions, the pH may be determined to =i:0.02 pH and the alkalinity to =i:0.6 ppm HCO3- for many naturally occurring bodies of fresh water.

  11. Extracellular pH modulates GABAergic neurotransmission in rat hypothalamus.

    PubMed

    Chen, Z L; Huang, R Q

    2014-06-20

    Changes in extracellular pH have a modulatory effect on GABAA receptor function. It has been reported that pH sensitivity of the GABA receptor is dependent on subunit composition and GABA concentration. Most of previous investigations focused on GABA-evoked currents, which only reflect the postsynaptic receptors. The physiological relevance of pH modulation of GABAergic neurotransmission is not fully elucidated. In the present studies, we examined the influence of extracellular pH on the GABAA receptor-mediated inhibitory neurotransmission in rat hypothalamic neurons. The inhibitory postsynaptic currents (IPSCs), tonic currents, and the GABA-evoked currents were recorded with whole-cell patch techniques on the hypothalamic slices from Sprague-Dawley rats at 15-26 postnatal days. The amplitude and frequency of spontaneous GABA IPSCs were significantly increased while the external pH was changed from 7.3 to 8.4. In the acidic pH (6.4), the spontaneous GABA IPSCs were reduced in amplitude and frequency. The pH induced changes in miniature GABA IPSCs (mIPSCs) similar to that in spontaneous IPSCs. The pH effect on the postsynaptic GABA receptors was assessed with exogenously applied varying concentrations of GABA. The tonic currents and the currents evoked by sub-saturating concentration of GABA ([GABA]) (10 μM) were inhibited by acidic pH and potentiated by alkaline pH. In contrast, the currents evoked by saturating [GABA] (1mM) were not affected by pH changes. We also investigated the influence of pH buffers and buffering capacity on pH sensitivity of GABAA receptors on human recombinant α1β2γ2 GABAA receptors stably expressed in HEK 293 cells. The pH influence on GABAA receptors was similar in HEPES- and MES-buffered media, and not dependent on protonated buffers, suggesting that the observed pH effect on GABA response is a specific consequence of changes in extracellular protons. Our data suggest that the hydrogen ions suppress the GABAergic neurotransmission

  12. Mapping Soil pH Buffering Capacity of Selected Fields

    NASA Technical Reports Server (NTRS)

    Weaver, A. R.; Kissel, D. E.; Chen, F.; West, L. T.; Adkins, W.; Rickman, D.; Luvall, J. C.

    2003-01-01

    Soil pH buffering capacity, since it varies spatially within crop production fields, may be used to define sampling zones to assess lime requirement, or for modeling changes in soil pH when acid forming fertilizers or manures are added to a field. Our objective was to develop a procedure to map this soil property. One hundred thirty six soil samples (0 to 15 cm depth) from three Georgia Coastal Plain fields were titrated with calcium hydroxide to characterize differences in pH buffering capacity of the soils. Since the relationship between soil pH and added calcium hydroxide was approximately linear for all samples up to pH 6.5, the slope values of these linear relationships for all soils were regressed on the organic C and clay contents of the 136 soil samples using multiple linear regression. The equation that fit the data best was b (slope of pH vs. lime added) = 0.00029 - 0.00003 * % clay + 0.00135 * % O/C, r(exp 2) = 0.68. This equation was applied within geographic information system (GIS) software to create maps of soil pH buffering capacity for the three fields. When the mapped values of the pH buffering capacity were compared with measured values for a total of 18 locations in the three fields, there was good general agreement. A regression of directly measured pH buffering capacities on mapped pH buffering capacities at the field locations for these samples gave an r(exp 2) of 0.88 with a slope of 1.04 for a group of soils that varied approximately tenfold in their pH buffering capacities.

  13. The Semen pH Affects Sperm Motility and Capacitation.

    PubMed

    Zhou, Ji; Chen, Li; Li, Jie; Li, Hongjun; Hong, Zhiwei; Xie, Min; Chen, Shengrong; Yao, Bing

    2015-01-01

    As the chemical environment of semen can have a profound effect on sperm quality, we examined the effect of pH on the motility, viability and capacitation of human sperm. The sperm in this study was collected from healthy males to avoid interference from other factors. The spermatozoa cultured in sperm nutrition solution at pH 5.2, 6.2, 7.2 and 8.2 were analyzed for sperm total motility, progressive motility (PR), hypo-osmotic swelling (HOS) rate, and sperm penetration. Our results showed that these parameters were similar in pH 7.2 and 8.2 sperm nutrition solutions, but decreased in pH 5.2 and 6.2 solutions. The HOS rate exhibited positive correlation with the sperm total motility and PR. In addition, the sperm Na(+)/K(+)-ATPase activity at different pHs was measured, and the enzyme activity was significantly lower in pH 5.2 and 6.2 media, comparing with that in pH 8.2 and pH 7.2 solutions. Using flow cytometry (FCM) and laser confocal scanning microscopy (LCSM) analysis, the intracellular Ca2(+ )concentrations of sperm cultured in sperm capacitation solution at pH 5.2, 6.2, 7.2 and 8.2 were determined. Compared with that at pH 7.2, the mean fluorescence intensity of sperm in pH 5.2 and 6.2 media decreased significantly, while that of pH 8.2 group showed no difference. Our results suggested that the declined Na(+)/K(+)-ATPase activity at acidic pHs result in decreased sperm movement and capacitation, which could be one of the mechanisms of male infertility.

  14. Biomedical PhD education--an international perspective.

    PubMed

    Mulvany, Michael J

    2013-05-01

    The PhD, otherwise known as the doctor of philosophy or Dr. Phil., is an internationally recognized degree, indicating that the PhD graduate has received training in research under supervision. Traditionally, the PhD was the route to an academic career, with most successful PhD graduates receiving tenured university positions. However, over the past 20-30 years, and particularly the past 10 years, the situation has changed dramatically. Governments in many countries have invested massively in PhD education, believing that trained researchers will contribute to the 'knowledge society', and thus increase the competitiveness of their countries in the future economies of the world. Thus, only a small fraction of PhD graduates now end up in academic research. Yet, the PhD remains a research degree, and indeed, institutions have become heavily dependent on PhD students for their research output. The situation has thus created a paradox. On the one hand, it has become essential for institutions to have many PhD students and for the research performed to be of the highest level. On the other hand, the careers of PhD students are not necessarily going to be directly related to the research performed during their PhD studies. The purpose of this article is to explore how this seeming paradox is being addressed in biomedicine and to show that far from being inconsistent that the two aspects are in fact complementary. The article is based on the author's experience as Head of Aarhus Graduate School of Health Sciences 2002-2011 and his work with graduate schools across Europe and internationally through the organization ORPHEUS.

  15. The Ph.D. Surplus - Realities and Illusions.

    ERIC Educational Resources Information Center

    Hansen, Harold P.

    Every 6 years the number of Ph.D.'s produced doubles. At this point about 1 percent of the babies born 27 years ago gets a Ph.D. This production rate will probably increase to 6 percent of the adult population. With the present situation in higher education, which includes an average retirement after 40 years of service, the supply already…

  16. Tracking the PhD Students' Daily Computer Use

    ERIC Educational Resources Information Center

    Sim, Kwong Nui; van der Meer, Jacques

    2015-01-01

    This study investigated PhD students' computer activities in their daily research practice. Software that tracks computer usage (Manic Time) was installed on the computers of nine PhD students, who were at their early, mid and final stage in doing their doctoral research in four different discipline areas (Commerce, Humanities, Health Sciences and…

  17. Effect of pH on biological phosphorus uptake.

    PubMed

    Serralta, J; Ferrer, J; Borrás, L; Seco, A

    2006-12-05

    An anaerobic aerobic laboratory scale sequencing batch reactor (SBR) was operated to study the effect of pH on enhanced biological phosphorus removal. Seven steady states were achieved under different operating conditions. In all of them, a slight variation in the pH value was observed during anaerobic phase. However, pH rose significantly during aerobic phase. The increase observed was due to phosphorus uptake and carbon dioxide stripping. When pH was higher than 8.2-8.25 the phosphorus uptake rate clearly decreased. The capability of Activated Sludge Model No. 2d (ASM2d) and Biological Nutrient Removal Model No. 1 (BNRM1) to simulate experimental results was evaluated. Both models successfully characterized the enhanced biological phosphorus removal performance of the SBR. Furthermore, BNRM1 also reproduced the pH variations observed and the decrease in the phosphorus uptake rate. This model includes a switch function in the kinetic expressions to represent the pH inhibition in biological processes. The pH inhibition constants related to polyphosphate storage process were obtained by adjusting model predictions to measured phosphorus concentrations. On the other hand, pH inhibition should be included in ASM2d to accurately simulate experimental phosphorus evolution observed in an A/O SBR.

  18. Variation of ocean pH in the Indonesia waters

    NASA Astrophysics Data System (ADS)

    Putri, Mutiara Rachmat; Setiawan, Agus; Safitri, Mediana

    2015-09-01

    The variation of ocean acidity (pH) in the Indonesia waters is strongly influenced by monsoon. Since the climate change tends to potentially change monsoonal variation over the Indonesian region, it will give also implication to the ocean pH variation. Moreover, changes of ocean pH will give effects to the marine lifes and their environment. In order to investigate this issue, we tried to calculate monthly variation of sea surface pH in the Indonesia waters based on monthly average temperature and salinity over past 18 years data. Temperature and salinity data used in this study were taken from the hydrodynamic model of Hamburg Shelf Ocean Model (HAMSOM), while alkalinity and dissolved inorganic carbon (DIC) were from World Ocean Atlas 2009 (WOA 2009). Algorithm from Ocean Carbon Model Intercomparison Project-version.3 (OCMIP-3) was used to calculate the pH. The estimation results indicate that pH variation in the Indonesia waters changes insignificantly over 18 years. El Nino Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) contribute to physical changes of seawater, but did not affect the pH significantly. The average pH of seawater is higher during northwest monsoon than during southeast monsoon.

  19. Research Collaboration and Commercialization: The PhD Candidate Perspective

    ERIC Educational Resources Information Center

    Dooley, Lawrence; Kenny, Breda

    2015-01-01

    This paper explores PhD students' perceptions of their entrepreneurial and commercial capabilities, their attitude towards university supports and the extent to which they engage in external collaboration. The study concentrated on current PhD researchers at one university in Ireland as a unit of analysis and provides encouraging evidence from the…

  20. Factors associated with ruminal pH at herd level.

    PubMed

    Geishauser, T; Linhart, N; Neidl, A; Reimann, A

    2012-08-01

    The objective of this study was to evaluate factors associated with ruminal pH at herd level. Four hundred and thirty-two cows of a Thuringian dairy herd were sampled before claw trimming using a rumen fluid scoop. Volume and pH of the rumen sample were measured, and lactation number, percentage of concentrates in the ration, days in milk (DIM), time of day, and daily milk yield were recorded. Rumen sampling was successful in 99.8% of the cows. The average sample volume was 25 mL. Rumen sample pH decreased with increasing percentage of concentrates in the ration. Ruminal pH decreased from calving to 77 DIM, and grew subsequently to 330 DIM. During the day, rumen pH followed a sinus curve, with maxima in the morning (0915 h) and afternoon (1533 h), and a minimum around noon (1227 h). Ruminal pH decreased with increasing daily milk yield. Lactation number interacted with daily milk yield on rumen pH. The percentage of concentrates in the ration, DIM, time of day, and daily milk yield were significant factors affecting ruminal pH at the herd level.

  1. Consideration of Factors Affecting Strip Effluent PH and Sodium Content

    SciTech Connect

    Peters, T.

    2015-07-29

    A number of factors were investigated to determine possible reasons for why the Strip Effluent (SE) can sometimes have higher than expected pH values and/or sodium content, both of which have prescribed limits. All of the factors likely have some impact on the pH values and Na content.

  2. International Mobility of French Ph.D.s

    ERIC Educational Resources Information Center

    Bonnard, Claire; Calmand, Julien; Giret, Jean-François

    2017-01-01

    This research investigates the determinants of international mobility of Ph.D.s upon graduation. It is based on a survey of 400 young Ph.D.s who graduated in France between 2003 and 2008, half of whom were still abroad more than six years after graduating. The impacts of personal, occupational and scientific characteristics on the successive…

  3. The PhD Viva: A Space for Academic Development

    ERIC Educational Resources Information Center

    Share, Michelle

    2016-01-01

    This study examined the viva experiences of 87 social science PhD graduates from three Irish higher education institutions through a questionnaire that assessed outcome, preparation, conduct and post-viva. The majority were awarded their PhD with minor corrections, considered their viva as a summative assessment, and emphasised its purpose as…

  4. The Undergraduate Origins of PhD Economists Revisited

    ERIC Educational Resources Information Center

    Stock, Wendy A.; Siegfried, John J.

    2015-01-01

    The authors update prior analyses of the undergraduate origins of individuals who earn a PhD in economics in the United States. They include the list of the top institutions worldwide graduating the largest number of undergraduates who subsequently earn an economics PhD from a U.S. university and lists of American institutions with the largest…

  5. A Renaissance in Engineering PhD Education

    ERIC Educational Resources Information Center

    Akay, Adnan

    2008-01-01

    This paper addresses the role of engineering PhD education and its relationship to innovation and technology, and the need to reconsider how we educate PhD engineers. Much of the effort on engineering education in the last two decades focused on undergraduate education with a few exceptions that relate to master degree programs. Doctoral education…

  6. The Importance of Having a Ph.D., Career Advice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A presentation on the importance of having a PhD to motivate Initiative to Maximize Student Diversity Program (IMSD) undergrads towards conducting research, pursuing careers in the biomedical field, applying to grad school, and getting a Ph.D., based upon ARS scientist's experiences as a student, a ...

  7. Can Community Colleges Survive the PhD Glut?

    ERIC Educational Resources Information Center

    Taylor, Anita

    The impact of the current employment situation on hiring faculty for community college teaching is examined. It is concluded that prospects for improving the quality of learning in community colleges are not particularly enhanced by the apparently growing surplus of new PhDs in our field. On the contrary, it is suggested that hiring PhDs for…

  8. PhDs in Australia, from the Beginning

    ERIC Educational Resources Information Center

    Dobson, Ian R.

    2012-01-01

    The Australian PhD is a relatively recent phenomenon, the first three being awarded in 1948. Before that, most Australian scholars typically went to Britain (predominantly) or the USA to undertake their doctoral studies. The aim of this research note is to provide a brief statistical history of the Australian PhD, noting changes over time between…

  9. Sugar sensing based on induced pH changes.

    PubMed

    Kim, Youngmi; Hilderbrand, Scott A; Weissleder, Ralph; Tung, Ching-Hsuan

    2007-06-14

    A sensory assembly consisting of a pH sensitive NIR dye and an arylboronic acid shows ratiometric absorption changes with increased fluorescence intensity upon addition of sugar in aqueous media; this demonstrates a new signal transduction mechanism for the detection of sugar based on pH changes induced in the microenvironment of the sensory assembly.

  10. Evanescent-wave spectroscopic fiber optic pH sensor

    NASA Astrophysics Data System (ADS)

    Egami, C.; Takeda, K.; Isai, M.; Ogita, M.

    1996-02-01

    We demonstrate a new type of fiber optic pH sensor, which is the application of evanescent-wave spectroscopic technique. A methyl red (MR)-doped-poly(methyl methacrylate) (PMMA) film that coated as part of cladding does function as a pH sensor probe. In this system MR doped in PMMA is used as indicator dye for pH measurement. The absorption spectrum shift in wavelength of indicator dye enables us to get the pH value. The sensor probe is immersed in water solution containing a small proportion of acetic acid over the wide pH range of 5.0 to 7.0. The chemical interaction between MR in sensor probe and hydrogen ion in the water solution causes a change in the dipole moment of MR, that is, the absorption spectrum macroscopically. The evanescent-wave spectroscopic technique provides the measurement of the absorption spectrum shift over a broad range of visible wavelength. The result of experiment was that MR absorption spectrum shifted by 40 nm every increase of 1.0 in pH. The small change in the pH value can be sensed as a large wavelength shift of pH indicator absorption spectrum.

  11. Rethinking PhD Learning Incorporating Communities of Practice

    ERIC Educational Resources Information Center

    Shacham, Miri; Od-Cohen, Yehudit

    2009-01-01

    This paper grows from research which focuses on the learning characteristics of PhD students, incorporating communities of practice both during their studies and beyond completion of their PhD, and drawing on theories of adult learning and lifelong learning. It shows how professional discourse enhances academic discourse through student engagement…

  12. The Early Development of Electronic pH Meters

    ERIC Educational Resources Information Center

    Hines, Wallis G.; de Levie, Robert

    2010-01-01

    A 19-year-old undergraduate at the University of Chicago, Kenneth Goode, in 1921 came up with the idea of an electronic pH meter, worked out some of its initial problems, and set in motion an international scientific effort that culminated in the current, wide availability of electronic pH meters. Except for the replacement of vacuum tubes by…

  13. Red-emitting dyes with photophysical and photochemical properties controlled by pH.

    PubMed

    Novakova, Veronika; Miletin, Miroslav; Kopecky, Kamil; Zimcik, Petr

    2011-12-09

    New unsymmetrical zinc azaphthalocyanines, bearing one substituted aniline as a peripheral substituent, were prepared by using a statistical condensation approach. Both fluorescence and singlet oxygen quantum yields were extremely low in DMF (Φ(F)<0.01, Φ(Δ)<0.02, respectively), but increased after the addition of sulfuric acid, reaching values comparable to controls without aniline substituents (Φ(F)=0.22-0.29, Φ(Δ)=0.40-0.59, respectively). This behavior was attributed to the deactivation of excited states by intramolecular charge transfer from a donor site (aniline), which was blocked after protonation in acidic media. In the protonated form, all of the compounds efficiently emitted light with λ(em) in the region of 662-675 nm. The investigated compounds were anchored to dioleoylphosphatidylcholine (DOPC) unilamellar vesicles and showed response to buffer pH. They were highly fluorescent at low pH values and almost nonfluorescent in neutral solutions. The pK(a) values were determined in DOPC vesicles and ranged between 2.2 and 4.2.

  14. Ambulatory pH Monitoring: New Advances and Indications

    PubMed Central

    Lutsi, Brant

    2006-01-01

    Ambulatory pH monitoring is currently used to objectively demonstrate abnormal degrees of esophageal acid exposure in patients with suspected gastroesophageal reflux disease. The development of wireless pH capsule recording has improved the tolerability and increased the duration of pH recording. Use of symptom-reflux correlation measures and pH testing, combining periods off and on PPI therapy, serves to optimize the performance of conventional pH testing. On the other hand, devices that measure bile reflux as well as nonacid reflux (esophageal impedance testing) have broadened the definition of gastroesophageal reflux and present potential explanations for patients with continued symptoms despite high-dose PPI therapy. These advances and their current and future clinical applications are reviewed

  15. ['Sandwich PhD': considerations for a successful experience abroad].

    PubMed

    Salvetti, Marina de Goes; Bueno, Mariana; Gastaldo, Denise; Kimura, Amélia Fumiko; Pimenta, Cibele Andrucioli de Mattos

    2013-03-01

    International PhD internship, named "Sandwich PhD" in Brazil is an opportunity to improve research abilities, to become known in academic area and to establish and/or increase work opportunities in an international context. In this article, we describe key factors regarding the planning and development of the "Sandwich PhD" as experienced by professors and students involved in the collaboration between the School of Nursing, University of São Paulo and Lawrence S. Bloomberg Faculty of Nursing, University of Toronto, Canada. We also present the participation of PhD students' network as an alternative to the "Sandwich PhD". An international experience, when well-planned and developed correctly, promotes students' personal and professional development and favors the internationalization of Brazilian graduate programs and research groups.

  16. High-Resolution pH Imaging of Living Bacterial Cells To Detect Local pH Differences

    PubMed Central

    Morimoto, Yusuke V.; Kami-ike, Nobunori; Miyata, Tomoko; Kawamoto, Akihiro; Kato, Takayuki

    2016-01-01

    ABSTRACT Protons are utilized for various biological activities such as energy transduction and cell signaling. For construction of the bacterial flagellum, a type III export apparatus utilizes ATP and proton motive force to drive flagellar protein export, but the energy transduction mechanism remains unclear. Here, we have developed a high-resolution pH imaging system to measure local pH differences within living Salmonella enterica cells, especially in close proximity to the cytoplasmic membrane and the export apparatus. The local pH near the membrane was ca. 0.2 pH unit higher than the bulk cytoplasmic pH. However, the local pH near the export apparatus was ca. 0.1 pH unit lower than that near the membrane. This drop of local pH depended on the activities of both transmembrane export components and FliI ATPase. We propose that the export apparatus acts as an H+/protein antiporter to couple ATP hydrolysis with H+ flow to drive protein export. PMID:27923921

  17. Thermal processing of acidified foods with pH 4.1 to pH 4.6

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shelf-stable acidified foods with a pH at or below 4.6 must be processed to achieve a 5-log reduction for vegetative bacterial pathogens. Published research does not exist to adequately support the Food and Drug Administration process filings for products with pH 4.1–4.6 or to define critical limits...

  18. Continuous pH monitoring in a perfused bioreactor system using an optical pH sensor

    NASA Technical Reports Server (NTRS)

    Jeevarajan, Antony S.; Vani, Sundeep; Taylor, Thomas D.; Anderson, Melody M.

    2002-01-01

    Monitoring and regulating the pH of the solution in a bioprocess is one of the key steps in the success of bioreactor operation. An in-line optical pH sensor, based on the optical absorption properties of phenol red present in the medium, was developed and tested in this work for use in NASA space bioreactors based on a rotating wall-perfused vessel system supporting a baby hamster kidney (BHK-21) cell culture. The sensor was tested over three 30-day and one 124-day cell runs. The pH sensor initially was calibrated and then used during the entire cell culture interval. The pH reported by the sensor was compared to that measured by a fiber optically coupled Shimadzu spectrophotometer and a blood gas analyzer. The maximum standard error of prediction for all the four cell runs for development pH sensor against BGA was +/-0.06 pH unit and for the fiber optically coupled Shimadzu spectrophotometer against the blood gas analyzer was +/-0.05 pH unit. The pH sensor system performed well without need of recalibration for 124 days. Copyright 2002 Wiley Periodicals, Inc.

  19. Physiological pH. Effects on posthypoxic proximal tubular injury.

    PubMed

    Zager, R A; Schimpf, B A; Gmur, D J

    1993-04-01

    After O2 deprivation, tissue acidosis rapidly self-corrects. This study assessed the effect of this pH correction on the induction, and pathways, of posthypoxic proximal tubular injury. In addition, ways to prevent the resultant injury were explored. Isolated rat proximal tubular segments (PTSs) were subjected to hypoxia/reoxygenation (50/30 or 30/50 minutes) under the following incubation conditions: 1) continuous pH 7.4, 2) continuous pH 6.8, or 3) hypoxia at pH 6.8 and reoxygenation at pH 7.4 (NaHCO3 or Tris base addition). Continuously oxygenated PTSs maintained under these same pH conditions served as controls. Lethal cell injury was assessed by lactate dehydrogenase (LDH) release. pH effects on several purported pathways of hypoxia/reoxygenation injury were also assessed (ATP depletion, lipid peroxidation, and membrane deacylation). Acidosis blocked hypoxic LDH release (pH 7.4, 50 +/- 2%; pH 6.8, 6 +/- 1%) without mitigating membrane deacylation or ATP depletion. During reoxygenation, minimal LDH was released (3-5%) if pH was held constant. However, if posthypoxic pH was corrected, immediate (< or = 5 minutes) and marked cell death (e.g., 55 +/- 3% with Tris) occurred. This was dissociated from lipid peroxidation or new deacylation, and it was preceded by a depressed ATP/ADP ratio (suggesting an acidosis-associated defect in hypoxic/posthypoxic cell energetics). Realkalinization injury was not inevitable, since it could be substantially blocked by 1) posthypoxic glycine addition, 2) transient posthypoxic hypothermia, or 3) allowing a 10-minute reoxygenation (cell recovery) period before base addition. Neither mannitol nor graded buffer Ca2+ deletion conferred protection. Acute pH correction caused no injury to continuously oxygenated PTSs. Conclusions are as follows: 1) Posthypoxic "pH shock" causes virtually immediate cell death, not by causing de novo injury but, rather, by removing the cytoprotective effect of acidosis. 2) This injury can be prevented by a

  20. Monitoring Survivability and Infectivity of Porcine Epidemic Diarrhea Virus (PEDv) in the Infected On-Farm Earthen Manure Storages (EMS)

    PubMed Central

    Tun, Hein M.; Cai, Zhangbin; Khafipour, Ehsan

    2016-01-01

    In recent years, porcine epidemic diarrhea virus (PEDv) has caused major epidemics, which has been a burden to North America’s swine industry. Low infectious dose and high viability in the environment are major challenges in eradication of this virus. To further understand the viability of PEDv in the infected manure, we longitudinally monitored survivability and infectivity of PEDv in two open earthen manure storages (EMS; previously referred to as lagoon) from two different infected swine farms identified in the province of Manitoba, Canada. Our study revealed that PEDv could survive up to 9 months in the infected EMS after the initial outbreak in the farm. The viral load varied among different layers of the EMS with an average of 1.1 × 105 copies/ml of EMS, independent of EMS temperature and pH. In both studied EMS, the evidence of viral replication was observed through increased viral load in the later weeks of the samplings while there was no new influx of infected manure into the EMS, which was suggestive of presence of potential alternative hosts for PEDv within the EMS. Decreasing infectivity of virus over time irrespective of increased viral load suggested the possibility of PEDv evolution within the EMS and perhaps in the new host that negatively impacted virus infectivity. Viral load in the top layer of the EMS was low and mostly non-infective suggesting that environmental factors, such as UV and sunlight, could diminish the replicability and infectivity of the virus. Thus, frequent agitation of the EMS that could expose virus to UV and sunlight might be a potential strategy for reduction of PEDv load and infectivity in the infected EMS. PMID:27014197

  1. Monitoring Survivability and Infectivity of Porcine Epidemic Diarrhea Virus (PEDv) in the Infected On-Farm Earthen Manure Storages (EMS).

    PubMed

    Tun, Hein M; Cai, Zhangbin; Khafipour, Ehsan

    2016-01-01

    In recent years, porcine epidemic diarrhea virus (PEDv) has caused major epidemics, which has been a burden to North America's swine industry. Low infectious dose and high viability in the environment are major challenges in eradication of this virus. To further understand the viability of PEDv in the infected manure, we longitudinally monitored survivability and infectivity of PEDv in two open earthen manure storages (EMS; previously referred to as lagoon) from two different infected swine farms identified in the province of Manitoba, Canada. Our study revealed that PEDv could survive up to 9 months in the infected EMS after the initial outbreak in the farm. The viral load varied among different layers of the EMS with an average of 1.1 × 10(5) copies/ml of EMS, independent of EMS temperature and pH. In both studied EMS, the evidence of viral replication was observed through increased viral load in the later weeks of the samplings while there was no new influx of infected manure into the EMS, which was suggestive of presence of potential alternative hosts for PEDv within the EMS. Decreasing infectivity of virus over time irrespective of increased viral load suggested the possibility of PEDv evolution within the EMS and perhaps in the new host that negatively impacted virus infectivity. Viral load in the top layer of the EMS was low and mostly non-infective suggesting that environmental factors, such as UV and sunlight, could diminish the replicability and infectivity of the virus. Thus, frequent agitation of the EMS that could expose virus to UV and sunlight might be a potential strategy for reduction of PEDv load and infectivity in the infected EMS.

  2. Identified EM Earthquake Precursors

    NASA Astrophysics Data System (ADS)

    Jones, Kenneth, II; Saxton, Patrick

    2014-05-01

    Many attempts have been made to determine a sound forecasting method regarding earthquakes and warn the public in turn. Presently, the animal kingdom leads the precursor list alluding to a transmission related source. By applying the animal-based model to an electromagnetic (EM) wave model, various hypotheses were formed, but the most interesting one required the use of a magnetometer with a differing design and geometry. To date, numerous, high-end magnetometers have been in use in close proximity to fault zones for potential earthquake forecasting; however, something is still amiss. The problem still resides with what exactly is forecastable and the investigating direction of EM. After a number of custom rock experiments, two hypotheses were formed which could answer the EM wave model. The first hypothesis concerned a sufficient and continuous electron movement either by surface or penetrative flow, and the second regarded a novel approach to radio transmission. Electron flow along fracture surfaces was determined to be inadequate in creating strong EM fields, because rock has a very high electrical resistance making it a high quality insulator. Penetrative flow could not be corroborated as well, because it was discovered that rock was absorbing and confining electrons to a very thin skin depth. Radio wave transmission and detection worked with every single test administered. This hypothesis was reviewed for propagating, long-wave generation with sufficient amplitude, and the capability of penetrating solid rock. Additionally, fracture spaces, either air or ion-filled, can facilitate this concept from great depths and allow for surficial detection. A few propagating precursor signals have been detected in the field occurring with associated phases using custom-built loop antennae. Field testing was conducted in Southern California from 2006-2011, and outside the NE Texas town of Timpson in February, 2013. The antennae have mobility and observations were noted for

  3. Optical fibre PH sensor based on immobilized indicator

    NASA Astrophysics Data System (ADS)

    Cai, Defu; Cao, Qiang; Han, JingHong; Cai, Jine; Li, YaTing; Zhu, ZeMin; Fan, Jie; Gao, Ning

    1991-08-01

    An optical fiber pH sensor which has the immobilized pH sensitive indicator dye reagents on the tip of the optical fiber has been studied. The probe is made by covalently immobilizing the phenol red, bromine phenol blue, or bromothymol blue on the polyacrylamide microsphere fixed by polyterafluoroethylene (PTFE) film. A gap between the dye and optical fiber was used to make the diffusion of the hydrogen ions easier. The parameters of the optical fiber pH sensor have been given completely. The ranges of measurement are 3.0 - 5.0 pH, 7.0 - 8.5 pH, and 8.0 - 10.0 pH for bromine phenol blue, phenol red, and bromothymol blue, respectively. The sensitivity is 66.6 mV/pH. The probe has a precision of better than 0.55 pH. The linear correlation coefficient is 0.999. The response time is 1 - 2 min. The hysteresis is 0.52%. The repeatability is 0.013 mV, while the stability is 0.015 pH/h.

  4. A ph sensor based on a flexible substrate

    NASA Astrophysics Data System (ADS)

    Huang, Wen-Ding

    pH sensor is an essential component used in many chemical, food, and bio-material industries. Conventional glass electrodes have been used to construct pH sensors, however, have some disadvantages. Glass electrodes are easily affected by alkaline or HF solution, they require a high input impedance pH meter, they often exhibit a sluggish response. In some specific applications, it is also difficult to use glass electrodes for in vivo biomedical or food monitoring applications due to the difficulty of size miniaturization, planarization and polymerization based on current manufacturing technologies. In this work, we have demonstrated a novel flexible pH sensor based on low-cost sol-gel fabrication process of iridium oxide (IrOx) sensing film (IROF). A pair of flexible miniature IrOx/AgCl electrode generated the action potential from the solution by electrochemical mechanism to obtain the pH level of the reagent. The fabrication process including sol-gel, thermal oxidation, and the electro-plating process of the silver chloride (AgCl) reference electrode were reported in the work. The IrOx film was verified and characterized using electron dispersive analysis (EDAX), scanning electron microscope (SEM), and x-ray diffraction (XRD). The flexible pH sensor's performance and characterization have been investigated with different testing parameters such as sensitivity, response time, stability, reversibility, repeatability, selectivity and temperature dependence. The flexible IrOx pH sensors exhibited promising sensing performance with a near-Nernstian response of sensitivity which is between --51.1mV/pH and --51.7mV/pH in different pH levels ranging from 1.5 to 12 at 25°C. Two applications including gastroesophageal reflux disease (GERD) diagnosis and food freshness wireless monitoring using our micro-flexible IrOx pH sensors were demonstrated. For the GERD diagnosing system, we embedded the micro flexible pH sensor on a 1.2cmx3.8cm of the capsule size of wireless sensor

  5. Improved granular activated carbon for the stabilization of wastewater PH

    SciTech Connect

    Farmer, R.W.; Dussert, B.W.; Kovacic, S.L.

    1996-12-31

    Laboratory studies have identified the cause of the pH rise, which occurs during water treatment with activated carbon, as an interaction between the naturally occurring anions and protons in the water and the carbon surface. The interaction can be described as an ion exchange type of phenomenon, in which the carbon surface sorbs the anions and corresponding hydronium ions from the water. These studies have shown that the anion sorption and resulting pH increase is independent of the raw material used for the activated carbon production, e.g. bituminous or subbituminous coal, peat, wood or coconut. Also, the pH excursions occur with virgin, reactivated, and acid washed granular carbons. Current pH control technologies focus on adjustment of the wastewater pH prior to discharge or recycle of the initial effluent water until the pH increase abates. However, improved water pH control options have been realized by altering the carbon surface through controlled oxidation rather than the water chemistry or extended preprocessing at the treatment site.

  6. Axillary pH and influence of deodorants.

    PubMed

    Stenzaly-Achtert, S.; Schölermann, A.; Schreiber, J.; Diec, K. H.; Rippke, F.; Bielfeldt, S.

    2000-05-01

    BACKGROUND/AIMS: In moist intertriginous regions, such as the armpit, the pH value is physiologically higher than in other skin regions. The regulation of the axillary pH-value was examined in an open study with 48 subjects in three groups with n=16 each. METHODS: In the first 10 days (run-in) the subjects received a standard treatment in the axilla with shaving, cleansing and application of a pH-neutral deodorant. This was followed by a 5 day treatment period with the three test products (pH5 Eucerin(R) Deodorant Roll-on, Deodorant Balsam Spray, Deodorant Cream). The study was concluded by a wash-out period with procedures identical to the run-in phase. The pH was measured with a calibrated pH-meter. RESULTS: A significant pH reduction was shown during the treatment period when compared to the run-in phase. The Deodorant Roll-on induced a reduction of the mean pH values from 6.1 to 5.3, the Deodorant Balsam Spray from 6.5 to 5.7 and the Deodorant Cream from 6.2 to 5.3. During the wash-out period all pH values returned to baseline. CONCLUSION: All of the deodorants tested demonstrated a significant reduction in axillary pH. There is evidence that a high skin pH promotes the growth of several microorganisms that produce malodor. Therefore, the regulation of pH may contribute to the deodorant efficacy of the test products.

  7. Anti-Leukemia Activity of In Vitro-Expanded Human Gamma Delta T Cells in a Xenogeneic Ph+ Leukemia Model

    PubMed Central

    Siegers, Gabrielle M.; Felizardo, Tania C.; Mathieson, A. Mark; Kosaka, Yoko; Wang, Xing-Hua; Medin, Jeffrey A.; Keating, Armand

    2011-01-01

    Gamma delta T cells (GDTc) lyse a variety of hematological and solid tumour cells in vitro and in vivo, and are thus promising candidates for cellular immunotherapy. We have developed a protocol to expand human GDTc in vitro, yielding highly cytotoxic Vgamma9/Vdelta2 CD27/CD45RA double negative effector memory cells. These cells express CD16, CD45RO, CD56, CD95 and NKG2D. Flow cytometric, clonogenic, and chromium release assays confirmed their specific cytotoxicity against Ph+ cell lines in vitro. We have generated a fluorescent and bioluminescent Ph+ cell line, EM-2eGFPluc, and established a novel xenogeneic leukemia model. Intravenous injection of EM-2eGFPluc into NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice resulted in significant dose-dependent bone marrow engraftment; lower levels engrafted in blood, lung, liver and spleen. In vitro-expanded human GDTc injected intraperitoneally were found at higher levels in blood and organs compared to those injected intravenously; GDTc survived at least 33 days post-injection. In therapy experiments, we documented decreased bone marrow leukemia burden in mice treated with GDTc. Live GDTc were found in spleen and bone marrow at endpoint, suggesting the potential usefulness of this therapy. PMID:21304898

  8. Near Infrared Spectral Determination of Human Tissue pH.

    DTIC Science & Technology

    1995-10-01

    Continuous Tissue pH Monitory in the Human Fetus During Labor", Obstet . Gynecol ., 55:523, 1980. 23. [Lemer 82] Lemer, H., et al., "Measurement of Glucose...Umbilical Blood pH", Am. J. Obstet . Gynecol ., 128: 901-903, 1977. 38. [Weyer 85] Weyer, L G., "Near Infrared Spectroscopy of Organic Substances," Applied...Patterns and Tissue pH in the Human Fetus", Am. J. Obstet . Gynecol ., 134:685-690, 1979. 24 Appendix I An Estimation Extension of the FKNN Algorithm In

  9. pH sensor based on boron nitride nanotubes

    NASA Astrophysics Data System (ADS)

    Huang, Q.; Bando, Y.; Zhao, L.; Zhi, C. Y.; Golberg, D.

    2009-10-01

    A submicrometer-sized pH sensor based on biotin-fluorescein-functionalized multiwalled BN nanotubes with anchored Ag nanoparticles is designed. Intrinsic pH-dependent photoluminescence and Raman signals in attached fluorescein molecules enhanced by Ag nanoparticles allow this novel nanohybrid to perform as a practical pH sensor. It is able to work in a submicrometer-sized space. For example, the sensor may determine the environmental pH of sub-units in living cells where a traditional optical fiber sensor fails because of spatial limitations.

  10. Imaging pH with hyperpolarized 13C.

    PubMed

    Gallagher, Ferdia A; Kettunen, Mikko I; Brindle, Kevin M

    2011-10-01

    pH is a fundamental physiological parameter that is tightly controlled by endogenous buffers. The acid-base balance is altered in many disease states, such as inflammation, ischemia and cancer. Despite the importance of pH, there are currently no routine methods for imaging the spatial distribution of pH in humans. The enormous gain in sensitivity afforded by dynamic nuclear polarization (DNP) has provided a novel way in which to image tissue pH using MR, which has the potential to be translated into the clinic. This review explores the advantages and disadvantages of current pH imaging techniques and how they compare with DNP-based approaches for the measurement and imaging of pH with hyperpolarized (13)C. Intravenous injection of hyperpolarized (13)C-labeled bicarbonate results in the rapid production of hyperpolarized (13)CO(2) in the reaction catalyzed by carbonic anhydrase. As this reaction is close to equilibrium in the body and is pH dependent, the ratio of the (13)C signal intensities from H(13)CO(3)(-) and (13)CO(2), measured using MRS, can be used to calculate pH in vivo. The application of this technique to a murine tumor model demonstrated that it measured predominantly extracellular pH and could be mapped in the animal using spectroscopic imaging techniques. A second approach has been to use the production of hyperpolarized (13)CO(2) from hyperpolarized [1-(13)C]pyruvate to measure predominantly intracellular pH. In tissues with a high aerobic capacity, such as the heart, the hyperpolarized [1-(13)C]pyruvate undergoes rapid oxidative decarboxylation, catalyzed by intramitochondrial pyruvate dehydrogenase. Provided that there is sufficient carbonic anhydrase present to catalyze the rapid equilibration of the hyperpolarized (13)C label between CO(2) and bicarbonate, the ratio of their resonance intensities may again be used to estimate pH, which, in this case, is predominantly intracellular. As both pyruvate and bicarbonate are endogenous molecules they

  11. Method for producing rapid pH changes

    DOEpatents

    Clark, John H.; Campillo, Anthony J.; Shapiro, Stanley L.; Winn, Kenneth R.

    1981-01-01

    A method of initiating a rapid pH change in a solution by irradiating the solution with an intense flux of electromagnetic radiation of a frequency which produces a substantial pK change to a compound in solution. To optimize the resulting pH change, the compound being irradiated in solution should have an excited state lifetime substantially longer than the time required to establish an excited state acid-base equilibrium in the solution. Desired pH changes can be accomplished in nanoseconds or less by means of picosecond pulses of laser radiation.

  12. Method for producing rapid pH changes

    DOEpatents

    Clark, J.H.; Campillo, A.J.; Shapiro, S.L.; Winn, K.R.

    A method of initiating a rapid pH change in a solution comprises irradiating the solution with an intense flux of electromagnetic radiation of a frequency which produces a substantial pK change to a compound in solution. To optimize the resulting pH change, the compound being irradiated in solution should have an excited state lifetime substantially longer than the time required to establish an excited state acid-base equilibrium in the solution. Desired pH changes can be accomplished in nanoseconds or less by means of picosecond pulses of laser radiation.

  13. Preparing MD-PhD students for clinical rotations: navigating the interface between PhD and MD training.

    PubMed

    Goldberg, Charles; Insel, Paul A

    2013-06-01

    Many aspects of MD-PhD training are not optimally designed to prepare students for their future roles as translational clinician-scientists. The transition between PhD research efforts and clinical rotations is one hurdle that must be overcome. MD-PhD students have deficits in clinical skills compared with those of their MD-only colleagues at the time of this transition. Reimmersion programs (RPs) targeted to MD-PhD students have the potential to help them navigate this transition.The authors draw on their experience creating and implementing an RP that incorporates multiple types of activities (clinical exam review, objective structured clinical examination, and supervised practice in patient care settings) designed to enhance the participants' skills and readiness for clinical efforts. On the basis of this experience, they note that MD-PhD students' time away from the clinical environment negatively affects their clinical skills, causing them to feel underprepared for clinical rotations. The authors argue that participation in an RP can help students feel more comfortable speaking with and examining patients and decrease their anxiety regarding clinical encounters. The authors propose that RPs can have positive outcomes for improving the transition from PhD to clinical MD training in dual-degree programs. Identifying and addressing this and other transitions need to be considered to improve the educational experience of MD-PhD students.

  14. Meet EPA Ecologist Paul Mayer, Ph.D.

    EPA Pesticide Factsheets

    EPA ecologist Paul Mayer, Ph.D. works in EPA's Groundwater and Ecosystem Restoration division where he studies riparian zones (the area along rivers and streams where the habitats are influenced by both the land and water) and stream restoration

  15. Meet EPA Scientist Heriberto Cabezas, Ph.D.

    EPA Pesticide Factsheets

    Heriberto Cabezas, Ph.D. is currently the Senior Science Advisor to the Sustainable Technology Division in EPA's National Risk Management Research Lab, where he works to advance the application of science and technologies to address sustainability.

  16. Meet EPA Microbiologist Eric Villegas, Ph.D.

    EPA Pesticide Factsheets

    Eric Villegas, Ph.D. is a research microbiologist in EPA's Office of Research and Development. His recent work focuses on next generation sequencing technology to better understand risks associated with waterborne parasites.

  17. Brenda K. Edwards, PhD | DCCPS/NCI/NIH

    Cancer.gov

    Brenda K. Edwards, PhD, has been with the Surveillance Research Program (SRP) and its predecessor organizations at the National Cancer Institute (NCI) since 1989, serving as SRP’s Associate Director from 1990-2011.

  18. Thermodynamic, Kinetic, Structural, and Computational Studies of the Ph3Sn-H, Ph3Sn-SnPh3, and Ph3Sn-Cr(CO)3C5Me5 Bond Dissociation Enthalpies.

    PubMed

    Cai, Xiaochen; Majumdar, Subhojit; Fortman, George C; Koppaka, Anjaneyulu; Serafim, Leonardo; Captain, Burjor; Temprado, Manuel; Hoff, Carl D

    2016-10-05

    The kinetics of the reaction of Ph3SnH with excess •Cr(CO)3C5Me5 = •Cr, producing HCr and Ph3Sn-Cr, was studied in toluene solution under 2-3 atm CO pressure in the temperature range of 17-43.5 °C. It was found to obey the rate equation d[Ph3Sn-Cr]/dt = k[Ph3SnH][•Cr] and exhibit a normal kinetic isotope effect (kH/kD = 1.12 ± 0.04). Variable-temperature studies yielded ΔH(‡) = 15.7 ± 1.5 kcal/mol and ΔS(‡) = -11 ± 5 cal/(mol·K) for the reaction. These data are interpreted in terms of a two-step mechanism involving a thermodynamically uphill hydrogen atom transfer (HAT) producing Ph3Sn• and HCr, followed by rapid trapping of Ph3Sn• by excess •Cr to produce Ph3Sn-Cr. Assuming an overbarrier of 2 ± 1 kcal/mol in the HAT step leads to a derived value of 76.0 ± 3.0 kcal/mol for the Ph3Sn-H bond dissociation enthalpy (BDE) in toluene solution. The reaction enthalpy of Ph3SnH with excess •Cr was measured by reaction calorimetry in toluene solution, and a value of the Sn-Cr BDE in Ph3Sn-Cr of 50.4 ± 3.5 kcal/mol was derived. Qualitative studies of the reactions of other R3SnH compounds with •Cr are described for R = (n)Bu, (t)Bu, and Cy. The dehydrogenation reaction of 2Ph3SnH → H2 + Ph3SnSnPh3 was found to be rapid and quantitative in the presence of catalytic amounts of the complex Pd(IPr)(P(p-tolyl)3). The thermochemistry of this process was also studied in toluene solution using varying amounts of the Pd(0) catalyst. The value of ΔH = -15.8 ± 2.2 kcal/mol yields a value of the Sn-Sn BDE in Ph3SnSnPh3 of 63.8 ± 3.7 kcal/mol. Computational studies of the Sn-H, Sn-Sn, and Sn-Cr BDEs are in good agreement with experimental data and provide additional insight into factors controlling reactivity in these systems. The structures of Ph3Sn-Cr and Cy3Sn-Cr were determined by X-ray crystallography and are reported. Mechanistic aspects of oxidative addition reactions in this system are discussed.

  19. Allosteric properties of PH domains in Arf regulatory proteins.

    PubMed

    Roy, Neeladri Sekhar; Yohe, Marielle E; Randazzo, Paul A; Gruschus, James M

    2016-01-01

    Pleckstrin Homology (PH) domains bind phospholipids and proteins. They are critical regulatory elements of a number enzymes including guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) for Ras-superfamily guanine nucleotide binding proteins such as ADP-ribosylation factors (Arfs). Recent studies have indicated that many PH domains may bind more than one ligand cooperatively. Here we discuss the molecular basis of PH domain-dependent allosteric behavior of 2 ADP-ribosylation factor exchange factors, Grp1 and Brag2, cooperative binding of ligands to the PH domains of Grp1 and the Arf GTPase-activating protein, ASAP1, and the consequences for activity of the associated catalytic domains.

  20. Meet EPA Biologist Laura Jackson, Ph.D.

    EPA Pesticide Factsheets

    Research Biologist Laura Jackson, Ph.D., has worked for the EPA for 22 years, leading research initiatives in a diversity of disciplines, including environmental monitoring, land use planning, and the impacts that urbanization has on an area's ecology

  1. Meet EPA Natural Resource Economist Marisa Mazzotta, Ph.D.

    EPA Pesticide Factsheets

    Marisa Mazzotta, Ph.D. currently works as an Economist at EPA's Atlantic Ecology Division. Her research focuses on the public's valuation and prioritization of natural resources, and the relationship between ecological changes and economic benefits.

  2. Meet EPA Scientist Susan Yee, Ph.D.

    EPA Pesticide Factsheets

    Susan Yee, Ph.D., is an ecologist at EPA's Gulf Ecology Division. She is working on the Puerto Rico Sustainable Communities program, developing decision support tools to evaluate how alternative decisions impact coastal ecosystem goods and services

  3. Meet EPA Scientist Jordan West, Ph.D.

    EPA Pesticide Factsheets

    Jordan West, Ph.D. is an aquatic ecologist at EPA. Her areas of expertise include freshwater & marine ecology, climate change impacts and adaptation, resilience and threshold theory, environmental risk assessment, expert elicitation & stakeholder processes

  4. Meet EPA Biologist Mitch Kostich, Ph.D.

    EPA Pesticide Factsheets

    EPA biologist, Mitch Kostich, Ph.D., conducts research to identify risks from exposures to chemical contaminants in water. His research uses technologies to prioritize contaminants in the environment based on the potential risks they pose to life

  5. Meet EPA Scientist Tim Shafer, Ph.D.

    EPA Pesticide Factsheets

    Tim Shafer earned his bachelor’s degree in biology and chemistry from Hope College in Holland, MI, in 1986 and his Ph.D. in pharmacology and environmental toxicology from Michigan State University in 1991.

  6. Meet EPA Chemist Quincy Teng, Ph.D.

    EPA Pesticide Factsheets

    EPA research chemist Quincy Teng, Ph.D., focuses on the application of metabolomics—a relatively new, specialized field of biochemistry focused on studying small molecules known as metabolites—on environmental and life sciences.

  7. Ashley Felix, Ph.D., M.P.H.

    Cancer.gov

    NCI Cancer Prevention Fellowship Program (CPFP) alumna, Ashley Felix, Ph.D., M.P.H., details her transition from pre-med student to an epidemiologist who focuses on studying the causes and prevention of disease.

  8. Meet EPA Environmental Engineer Terra Haxton, Ph.D.

    EPA Pesticide Factsheets

    EPA Environmental Engineer Terra Haxton, Ph.D., uses computer simulation models to protect drinking water. She investigates approaches to help water utilities be better prepared to respond to contamination incidents in their distribution systems.

  9. Frequently Asked Questions for Parents of Children with PH

    MedlinePlus

    ... Process: Some First Steps Adoption Success Story Watch Classroom Recordings Empowered Patient Online Toolkit Tab 1: Very ... Kathy Groebner Education Programs Patients and Caregivers PHA Classroom PHA on the Road: PH Patients and Families ...

  10. Colorimetric pH measurement of animal cell culture media.

    PubMed

    Jang, Juno; Moon, Soo-Jin; Hong, Sung-Hwan; Kim, Ik-Hwan

    2010-11-01

    Most animal cell culture media can be buffered using bicarbonate and high pressure CO(2) in a closed system. However, in an open system, the pH of the culture media increases continuously due to the marked difference in CO(2) pressure between the culture media and the atmosphere. Therefore, it is important to measure the exact pH of the culture media in an intact closed system. In this study, a pH measurement method was developed using visible light. The pH was calculated from light absorbance by the cells and by the culture media. This method was successfully applied to both suspension and anchorage-dependent cell cultures.

  11. pH Effects on Electrospray Ionization Efficiency

    NASA Astrophysics Data System (ADS)

    Liigand, Jaanus; Laaniste, Asko; Kruve, Anneli

    2017-03-01

    Electrospray ionization efficiency is known to be affected by mobile phase composition. In this paper, a detailed study of analyte ionization efficiency dependence on mobile phase pH is presented. The pH effect was studied on 28 compounds with different chemical properties. Neither p K a nor solution phase ionization degree by itself was observed to be sufficient at describing how aqueous phase pH affects the ionization efficiency of the analyte. Therefore, the analyte behavior was related to various physicochemical properties via linear discriminant analyses. Distinction between pH-dependent and pH-independent compounds was achieved using two parameters: number of potential charge centers and hydrogen bonding acceptor capacity (in the case of 80% acetonitrile) or polarity of neutral form of analyte and p K a (in the case of 20% acetonitrile). It was also observed that decreasing pH may increase ionization efficiency of a compound by more than two orders of magnitude.

  12. Commentary: PhDs in biochemistry education-5 years later.

    PubMed

    Offerdahl, Erika G; Momsen, Jennifer L; Osgood, Marcy

    2014-01-01

    In this commentary, the discussion of PhDs in biochemistry education research is expanded to explore a number of diverse pathways leading to a competitive research program in biochemistry education research.

  13. Commentary: PhDs in Biochemistry Education--5 Years Later

    ERIC Educational Resources Information Center

    Offerdahl, Erika G.; Momsen, Jennifer L.; Osgood, Marcy

    2014-01-01

    In this commentary, the discussion of PhDs in biochemistry education research is expanded to explore a number of diverse pathways leading to a competitive research program in biochemistry education research.

  14. Meet EPA Scientist Dermont Bouchard, Ph.D.

    EPA Pesticide Factsheets

    EPA Scientist Dermont Bouchard, Ph.D., is working to better understand how tiny nanomaterials might be released into the environment. His research helps regulators and other decision-makers lower risks and better protect human health and the environment

  15. The Training and Work of Ph.D. Physical Scientists

    NASA Astrophysics Data System (ADS)

    Smith, S. J.; Schweitzer, A. E.

    2003-05-01

    Doctoral education has often been viewed as the pinnacle of the formal education system. How useful is doctoral training in one's later career? In an NSF-funded project, we set out to perform a study of the training, careers, and work activities of Ph.D. physical scientists. The study included both in-depth interviews and a survey sent out to a sample of Ph.D. holders 4-8 years after graduation. Come and find out the results of this study: What skills are most Ph.D. physical scientists using? What should graduate programs be teaching? Are Ph.D.'s who are working in their specific field of training happier than their counterparts working different jobs? What skills and preparation lead to future job satisfaction, perhaps the most important indicator of the "success" of graduate education? A preprint and further details can be found at the project web site at: spot.colorado.edu/ phdcarer.

  16. Meet EPA Scientist Valerie Zartarian, Ph.D.

    EPA Pesticide Factsheets

    Senior exposure scientist and research environmental engineer Valerie Zartarian, Ph.D. helps build computer models and other tools that advance our understanding of how people interact with chemicals.

  17. Meet EPA Scientist Jody Shoemaker, Ph.D.

    EPA Pesticide Factsheets

    EPA research chemist Jody Shoemaker, Ph.D., works to support Agency efforts to protect drinking water. She helps develop methods for analyzing organic chemicals on the Drinking Water Contaminant Candidate List (CCL).

  18. Meet EPA Engineer Shawn Ryan, Ph.D.

    EPA Pesticide Factsheets

    Shawn Ryan, Ph.D. is a chemical engineer at EPA's National Homeland Security Research Center. He has worked at EPA for 12 years, nine of which have been devoted to leading research to support decontamination and consequence management.

  19. Meet EPA Chemist Linda Sheldon, Ph.D.

    EPA Pesticide Factsheets

    Environmental chemist Linda Sheldon, Ph.D, is the Associate Director for Human Heath in the National Exposure Research Laboratory. She studies environmental exposure, particularly focusing on children's environments and their contact with chemicals.

  20. Meet EPA Scientist Jeff Szabo, Ph.D.

    EPA Pesticide Factsheets

    EPA scientist Jeff Szabo, Ph.D., has worked for the EPA’s National Homeland Security Research Center since 2005. He conducts and manages water security research projects at EPA’s Test and Evaluation facility.

  1. Meet EPA Scientist Blake Schaeffer, Ph.D.

    EPA Pesticide Factsheets

    EPA research ecologist Blake Schaeffer, Ph.D. focuses on ways to use satellite remote sensing technology to monitor water quality. His research interests broadly include deriving water quality parameters in coasts, estuaries, and lakes using satellites

  2. Meet EPA Scientist Michael Nye, Ph.D.

    EPA Pesticide Factsheets

    Michael Nye, Ph.D., is a social scientist who studies natural risk, socio-demographic change and sustainable behavior. Prior to joining EPA, he worked for the UK Environment Agency in flood risk management and emergency preparedness

  3. [Photohemolysis sensitized by psoralen: dependence on pH].

    PubMed

    Potapenko, A Ia; Belichenko, I V; Mamedov, I S; Zhuravel', N N; Kiagova, A A; Beijersbergen van Henegouwen, G M J; De Vries, Ch

    2007-01-01

    The effect of pH on the hemolysis of erythrocytes photosensitized (366 nm, 23 Wt/m2) by psoralen has been studied. The dependence of the photohemolysis rate (V) on irradiation dose (D) was described by the equation V = Vo + kD, where Vo is the rate of hemolysis without irradiation (dark), and k is the constant. The index of the power at dose x was approximately equal to 2, and its value did not change as the pH of the erythrocyte suspension was changed. It was found that changes in pH led to a sharp change in the value of coefficient k and correspondingly V. The lowest rate of photohemolysis was observed in the pH range from 8.0 to 8.4. As pH was changed from 3.4 to 9.0 or from 8.0 to 7.4, the V value increased approximately twofold. At pH below 7.4, an abrupt increase (approximately fourfold) in V was observed, with the pK value being equal to 7.3. The psoralen molecule lacks titratable acidic and basic groups; therefore, the effects of pH can hardly be assigned to changes in the photophysical properties of the sensitizer. The increase in V in the alkaline region is prohably related to the acceleration of photooxidation of reduced glutathione, whereas the jump of V at pH of about 7.3 may be due to the titration of the product of psoralen photooxidation. The latter assumption is confirmed by the data of hign performance liquid chromatography. In these experiments, psoralen was oxidized in ethanol and mixed with the phosphate buffer at different pH values followed by a qualitative and quantitative analysis by high performance liquid chromatography of photoproducts. Several photoproducts of psoralen have been identified whose content depended on pH. The curve of titration of one photoproduct was similar in shape to the pH dependence of psoralen-photosensitized hemolysis.

  4. The PhD in Writing Accompanied by an Exegesis

    ERIC Educational Resources Information Center

    Arnold, Josie

    2005-01-01

    The position of this paper is to further the discussion on what constitutes academic assessment in the PhD by artefact and exegesis. In doing so, it explores some of the ideas that arose in setting up the PhD in creative writing at Swinburne University of Technology. Thus, I: (1) survey some of the questions that arise about the journeys made by…

  5. Mouthguard and sports drinks on tooth surface pH.

    PubMed

    Maeda, Y; Yang, T-C; Miyanaga, H; Tanaka, Y; Ikebe, K; Akimoto, N

    2014-09-01

    The influence of sports drinks and mouthguards on the pH level of tooth surface was examined. A custom-made mouthguard was fabricated for each subject. The pH level was measured by electric pH meter with sensitivity of 0.01 up to 30 min. Sports drinks (pH=3.75) containing 9.4% sugar were used in this study. Measurements were performed on a cohort of 23 female subjects without a mouthguard (control), wearing a mouthguard only (MG), wearing a mouthguard after 30 ml sports drink intake (SD+MG), wearing a mouthguard during a 5-min jogging exercise (MG+EX) and wearing a mouthguard during jogging after sports drink intake (SD+MG+EX). For 7 male subjects, the same measurements were performed while a sports drink was taken over the mouthguard (MG+SD, MD+EX+SD). MG showed statistically higher pH level than control (p<0.05). SD+MG exhibited a significant decrease in pH level, and SD+MG+EX exhibited even below the critical level of pH 5.5 in some subjects. When sports drinks were taken over the mouthguard, no significant differences in pH level were observed among the different conditions.Within the limitations of this study, it was suggested that wearing a mouthguard during exercise is in itself not a possible risk factor for dental caries, while wearing a mouthguard after consuming sports drinks is.

  6. Teaching Human Digestion and pH Using Technology

    ERIC Educational Resources Information Center

    Kim, Hanna

    2008-01-01

    Testing the pH of various liquids is one of the most popular activities in 5th- through 8th-grade classrooms. The author presents an extensive pH-testing lesson based on a 5E (engagement, exploration, explanation, extension, and evaluation) teaching model. The activity provides students with the opportunity to learn about pH and how it relates to…

  7. MD-PhD training: looking back and looking forward.

    PubMed

    Bonham, Ann C

    2014-01-01

    MD-PhD programs provide rigorous, integrated training for physician-scientists, enabling them to frame scientific questions in unique ways and to apply clinical insight to fundamental science. Few would question the influential contributions of MD-PhD physician-scientists in advancing medical science. In this issue of Academic Medicine, Jeffe et al affirm high levels of excellence in educational outcomes from MD-PhD training programs at U.S. MD-granting medical schools, especially programs that receive funding from the NIH Medical Scientist Training Program (MSTP). The author of this commentary observes that, in the face of current economic pressures, comprehensive, longitudinal national outcomes data from MSTP- and non-MSTP-funded MD-PhD programs will help verify the value provided by MD-PhD physician-scientists. She proposes that MD-PhD programs should better prepare the next generation of physician-scientists for future research environments, which will provide new technologies, venues, and modalities. These research environments will be more closely integrated within health care delivery systems, extend into diverse communities and regions, and employ complex technologies. MD-PhD physician-scientists also will train and gain expertise in broadening areas of research, such as health policy, health economics, clinical epidemiology, and medical informatics. Program leaders are ideally situated to foster innovative learning environments and methodologies. By sharing their innovations, they can help ensure production of a diverse MD-PhD physician-scientist workforce, prepared to engage in myriad research opportunities to meet patient and population needs in a new environment.

  8. Automated high precision secondary pH measurements

    NASA Astrophysics Data System (ADS)

    Bastkowski, F.; Jakobsen, P. T.; Stefan, F.; Kristensen, H. B.; Jensen, H. D.; Kawiecki, R.; Wied, C. E.; Kauert, A.; Seidl, B.; Spitzer, P.; Eberhardt, R.; Adel, B.

    2013-04-01

    A new setup for high precision, automated secondary pH measurements together with a reference measurement procedure has been developed and tested in interlaboratory comparisons using buffers pH 4.005, pH 7.000, and pH 10.012 at 25 °C and 37 °C. Using primary buffers as standards, a standard uncertainty in pH better than 0.005 can be reached. The central measuring device is a one piece, thermostatted cell of PFA (perfluoroalkoxy) with a built-in Hamilton® Single Pore™ Glass electrode. Due to its flow-through principle this device allows pH measurements with low consumption of measurement solutions. The very hydrophobic and smooth PFA as construction material facilitates complete emptying of the cell. Furthermore, the tempering unit affords very precise temperature control and hence contributes to the low target uncertainty of the produced secondary buffer solutions. Use of a symmetric measurement sequence and the two point calibration was sufficient to reach high precision and accuracy.

  9. Monitoring pH and ORP in a SHARON reactor.

    PubMed

    Claros, J; Serralta, J; Seco, A; Ferrer, J; Aguado, D

    2011-01-01

    This paper analyses the valuable information provided by the on-line measurements of pH and oxidation reduction potential (ORP) in a continuous single high ammonia removal over nitrite (SHARON) reactor. A laboratory-scale SHARON reactor equipped with pH, ORP, electric conductivity and dissolved oxygen (DO) probes has been operated for more than one year. Nitrogen removal over nitrite has been achieved by adding methanol at the beginning of anoxic stages. Time evolution of pH and ORP along each cycle allows identifying the decrease in nitritation rate when ammonia is consumed during the aerobic phase and the end of the denitrification process during the anoxic phase. Therefore, monitoring pH and ORP can be used to develop a real-time control system aimed at optimizing the length of both aerobic and anoxic stages. Real-time control of methanol addition can be carried out by using the information provided by these probes: excessive methanol addition in the anoxic stage is clearly detected in the ORP profile of the following aerobic phase, while a deficit of methanol is detected in both pH and ORP profiles of that anoxic phase. Moreover, other valuable information such as the amount of ammonia nitrified, failures in DO measurements, excessive stirring during the anoxic stage and methanol dosage in the aerobic phase was also provided by the pH and ORP profiles.

  10. Structure of human saposin A at lysosomal pH

    SciTech Connect

    Hill, Chris H.; Read, Randy J.; Deane, Janet E.

    2015-06-27

    A 1.8 Å resolution structure of the sphingolipid activator protein saposin A has been determined at pH 4.8, the physiologically relevant lysosomal pH for hydrolase enzyme activation and lipid-transfer activity. The saposins are essential cofactors for the normal lysosomal degradation of complex glycosphingolipids by acid hydrolase enzymes; defects in either saposin or hydrolase function lead to severe metabolic diseases. Saposin A (SapA) activates the enzyme β-galactocerebrosidase (GALC), which catalyzes the breakdown of β-d-galactocerebroside, the principal lipid component of myelin. SapA is known to bind lipids and detergents in a pH-dependent manner; this is accompanied by a striking transition from a ‘closed’ to an ‘open’ conformation. However, previous structures were determined at non-lysosomal pH. This work describes a 1.8 Å resolution X-ray crystal structure determined at the physiologically relevant lysosomal pH 4.8. In the absence of lipid or detergent at pH 4.8, SapA is observeed to adopt a conformation closely resembling the previously determined ‘closed’ conformation, showing that pH alone is not sufficient for the transition to the ‘open’ conformation. Structural alignments reveal small conformational changes, highlighting regions of flexibility.

  11. Data collection and analysis strategies for phMRI.

    PubMed

    Mandeville, Joseph B; Liu, Christina H; Vanduffel, Wim; Marota, John J A; Jenkins, Bruce G

    2014-09-01

    Although functional MRI traditionally has been applied mainly to study changes in task-induced brain function, evolving acquisition methodologies and improved knowledge of signal mechanisms have increased the utility of this method for studying responses to pharmacological stimuli, a technique often dubbed "phMRI". The proliferation of higher magnetic field strengths and the use of exogenous contrast agent have boosted detection power, a critical factor for successful phMRI due to the restricted ability to average multiple stimuli within subjects. Receptor-based models of neurovascular coupling, including explicit pharmacological models incorporating receptor densities and affinities and data-driven models that incorporate weak biophysical constraints, have demonstrated compelling descriptions of phMRI signal induced by dopaminergic stimuli. This report describes phMRI acquisition and analysis methodologies, with an emphasis on data-driven analyses. As an example application, statistically efficient data-driven regressors were used to describe the biphasic response to the mu-opioid agonist remifentanil, and antagonism using dopaminergic and GABAergic ligands revealed modulation of the mesolimbic pathway. Results illustrate the power of phMRI as well as our incomplete understanding of mechanisms underlying the signal. Future directions are discussed for phMRI acquisitions in human studies, for evolving analysis methodologies, and for interpretative studies using the new generation of simultaneous PET/MRI scanners. This article is part of the Special Issue Section entitled 'Neuroimaging in Neuropharmacology'.

  12. Data Collection and Analysis Strategies for phMRI

    PubMed Central

    Mandeville, Joseph B.; Liu, Christina H.; Vanduffel, Wim; Marota, John J.A.; Jenkins, Bruce G.

    2014-01-01

    Although functional MRI traditionally has been applied mainly to study changes in task-induced brain function, evolving acquisition methodologies and improved knowledge of signal mechanisms have increased the utility of this method for studying responses to pharmacological stimuli, a technique often dubbed “phMRI”. The proliferation of higher magnetic field strengths and the use of exogenous contrast agent have boosted detection power, a critical factor for successful phMRI due to the restricted ability to average multiple stimuli within subjects. Receptor-based models of neurovascular coupling, including explicit pharmacological models incorporating receptor densities and affinities and data-driven models that incorporate weak biophysical constraints, have demonstrated compelling descriptions of phMRI signal induced by dopaminergic stimuli. This report describes phMRI acquisition and analysis methodologies, with an emphasis on data-driven analyses. As an example application, statistically efficient data-driven regressors were used to describe the biphasic response to the mu-opioid agonist remifentanil, and antagonism using dopaminergic and GABAergic ligands revealed modulation of the mesolimbic pathway. Results illustrate the power of phMRI as well as our incomplete understanding of mechanisms underlying the signal. Future directions are discussed for phMRI acquisitions in human studies, for evolving analysis methodologies, and for interpretative studies using the new generation of simultaneous PET/MRI scanners. PMID:24613447

  13. Growth and functional responses of different cultivars of Lotus corniculatus to aluminum and low pH stress.

    PubMed

    Pavlovkin, Ján; Pal'ove-Balang, Peter; Kolarovic, Lukás; Zelinová, Veronika

    2009-09-15

    Aluminum toxicity is an important stress factor in acid soils. Growth, respiration and permeability properties of root cells were studied in five cultivars of Lotus corniculatus subjected to aluminum (Al) or low pH stress. The cultivars showed significant differences in root elongation under stress conditions, which correlated with changes in membrane potential (E(M)) of root cortical cells. A pH drop from 5.5 to 4.0 resulted in significant membrane depolarization and root growth inhibition. The strongest inhibition was observed in cv. São Gabriel (33.6%) and least in cv. UFRGS (25.8%). Application of an extremely high Al concentration (2mM) stopped the root growth in cv. INIA Draco, while inhibition in cv. UFRGS reached only 75%. The E(M) values of cortical cells of Lotus roots varied between -115 and -144mV. Treatment with 250microM of AlCl(3) (pH 4) resulted in rapid membrane depolarization. The extent of the membrane depolarization ranged between 51mV (cv. UFGRS) and 16mV (cv. INIA Draco). The membrane depolarization was followed by a loss of K(+) from Al-treated roots (2mM Al) and resulted in a decrease of the diffusion potential (E(D)). The total amount of K(+) in Al-treated roots dropped from 31.4 to 16.8micromolg(-1) FW in sensitive cv. INIA Draco, or from 26.1 to 22.7micromolg(-1) FW in tolerant cv. UFGRS. The rate of root respiration under control conditions as well as under Al treatment was higher in cv. INIA Draco than in cv. UFRGS. Al-induced inhibition of root respiration was 21-34% of the control.

  14. Comparing Metal Leaching and Toxicity from High pH, Low pH, and High Ammonia Fly Ash

    SciTech Connect

    Palumbo, Anthony Vito; Phillips, Jana Randolph; Fagan, Lisa Anne; Drake, Meghan M; Ruther, Rose Emily; Fisher, L. Suzanne; Amonette, J. E.

    2007-01-01

    Previous work with both class F and class C fly ash indicated minimal leaching from most fly ashes tested. However, the addition of NOx removal equipment might result in higher levels of ammonia in the fly ash. We have recently been testing fly ash with a wide range of pH (3.7-12.4) originating from systems with NOx removal equipment. Leaching experiments were done using dilute CaCl2 solutions in batch and columns and a batch nitric acid method. All methods indicated that the leaching of heavy metals was different in the highest ammonia sample tested and the high pH sample. However, toxicity testing with the Microtox system has indicated little potential toxicity in leachates except for the fly ash at the highest pH (12.4). When the leachate from the high pH fly ash was neutralized, toxicity was eliminated.

  15. Comparing metal leaching and toxicity from high pH, low pH, and high ammonia fly ash

    SciTech Connect

    Palumbo, Anthony V.; Tarver, Jana R.; Fagan, Lisa A.; McNeilly, Meghan S.; Ruther, Rose; Fisher, L. S.; Amonette, James E.

    2007-07-01

    Previous work with both class F and class C fly ash indicated minimal leaching from most fly ashes tested. However, the addition of NOx removal equipment might result in higher levels of ammonia in the fly ash. We have recently been testing fly ash with a wide range of pH (3.7–12.4) originating from systems with NOx removal equipment. Leaching experiments were done using dilute CaCl2 solutions in batch and columns and a batch nitric acid method. All methods indicated that the leaching of heavy metals was different in the highest ammonia sample tested and the high pH sample. However, toxicity testing with the Microtox* system has indicated little potential toxicity in leachates except for the fly ash at the highest pH (12.4). When the leachate from the high pH fly ash was neutralized, toxicity was eliminated.

  16. Characterisation and deployment of an immobilised pH sensor spot towards surface ocean pH measurements.

    PubMed

    Clarke, Jennifer S; Achterberg, Eric P; Rérolle, Victoire M C; Abi Kaed Bey, Samer; Floquet, Cedric F A; Mowlem, Matthew C

    2015-10-15

    The oceans are a major sink for anthropogenic atmospheric carbon dioxide, and the uptake causes changes to the marine carbonate system and has wide ranging effects on flora and fauna. It is crucial to develop analytical systems that allow us to follow the increase in oceanic pCO2 and corresponding reduction in pH. Miniaturised sensor systems using immobilised fluorescence indicator spots are attractive for this purpose because of their simple design and low power requirements. The technology is increasingly used for oceanic dissolved oxygen measurements. We present a detailed method on the use of immobilised fluorescence indicator spots to determine pH in ocean waters across the pH range 7.6-8.2. We characterised temperature (-0.046 pH/°C from 5 to 25 °C) and salinity dependences (-0.01 pH/psu over 5-35), and performed a preliminary investigation into the influence of chlorophyll on the pH measurement. The apparent pKa of the sensor spots was 6.93 at 20 °C. A drift of 0.00014 R (ca. 0.0004 pH, at 25 °C, salinity 35) was observed over a 3 day period in a laboratory based drift experiment. We achieved a precision of 0.0074 pH units, and observed a drift of 0.06 pH units during a test deployment of 5 week duration in the Southern Ocean as an underway surface ocean sensor, which was corrected for using certified reference materials. The temperature and salinity dependences were accounted for with the algorithm, R=0.00034-0.17·pH+0.15·S(2)+0.0067·T-0.0084·S·1.075. This study provides a first step towards a pH optode system suitable for autonomous deployment. The use of a short duration low power illumination (LED current 0.2 mA, 5 μs illumination time) improved the lifetime and precision of the spot. Further improvements to the pH indicator spot operations include regular application of certified reference materials for drift correction and cross-calibration against a spectrophotometric pH system. Desirable future developments should involve novel

  17. pH measurement and a rational and practical pH control strategy for high throughput cell culture system.

    PubMed

    Zhou, Haiying; Purdie, Jennifer; Wang, Tongtong; Ouyang, Anli

    2010-01-01

    The number of therapeutic proteins produced by cell culture in the pharmaceutical industry continues to increase. During the early stages of manufacturing process development, hundreds of clones and various cell culture conditions are evaluated to develop a robust process to identify and select cell lines with high productivity. It is highly desirable to establish a high throughput system to accelerate process development and reduce cost. Multiwell plates and shake flasks are widely used in the industry as the scale down model for large-scale bioreactors. However, one of the limitations of these two systems is the inability to measure and control pH in a high throughput manner. As pH is an important process parameter for cell culture, this could limit the applications of these scale down model vessels. An economical, rapid, and robust pH measurement method was developed at Eli Lilly and Company by employing SNARF-4F 5-(-and 6)-carboxylic acid. The method demonstrated the ability to measure the pH values of cell culture samples in a high throughput manner. Based upon the chemical equilibrium of CO(2), HCO(3)(-), and the buffer system, i.e., HEPES, we established a mathematical model to regulate pH in multiwell plates and shake flasks. The model calculates the required %CO(2) from the incubator and the amount of sodium bicarbonate to be added to adjust pH to a preset value. The model was validated by experimental data, and pH was accurately regulated by this method. The feasibility of studying the pH effect on cell culture in 96-well plates and shake flasks was also demonstrated in this study. This work shed light on mini-bioreactor scale down model construction and paved the way for cell culture process development to improve productivity or product quality using high throughput systems.

  18. Effect of systemic pH on pH sub i and lactic acid generation in exhaustive forearm exercise

    SciTech Connect

    Hood, V.L.; Schubert, C.; Keller, U.; Mueller, S. Univ. of Vermont College of Medicine, Burlington )

    1988-09-01

    To investigate whether changes in systemic pH affect intracellular pH (pH{sub i}), energy-rich phosphates, and lactic acid generation in muscle, eight normal volunteers performed exhaustive forearm exercise with arterial blood flow occluded for 2 min on three occasions. Subjects ingested 4 mmol/kg NH{sub 4}Cl (acidosis; A) or NaHCO{sub 3} (alkalosis; B) or nothing (control; C) 3 h before the exercise. Muscle pH{sub i} and phosphocreatine (PCr) content were measured with {sup 31}P-nuclear magnetic resonance ({sup 31}P-NMR) spectroscopy during exercise and recovery. Lactate output during 0.5-7 min of recovery was calculated as deep venous-arterial concentration differences times forearm blood flow. Before exercise, blood pH and bicarbonate were lower in acidosis than alkalosis and intermediate in control. Lactic acid output during recovery was less with A than B and intermediate in C. PCr utilization and resynthesis were not affected by extracellular pH changes. pH{sub i} did not differ before exercise or at its end. Hence systemic acidosis inhibited and alkalosis stimulated lactic acid output. These findings suggest that systemic pH regulates cellular acid production, protecting muscle pH, at the expense of energy availability.

  19. Coral calcifying fluid pH is modulated by seawater carbonate chemistry not solely seawater pH.

    PubMed

    Comeau, S; Tambutté, E; Carpenter, R C; Edmunds, P J; Evensen, N R; Allemand, D; Ferrier-Pagès, C; Tambutté, S; Venn, A A

    2017-01-25

    Reef coral calcification depends on regulation of pH in the internal calcifying fluid (CF) in which the coral skeleton forms. However, little is known about calcifying fluid pH (pHCF) regulation, despite its importance in determining the response of corals to ocean acidification. Here, we investigate pHCF in the coral Stylophora pistillata in seawater maintained at constant pH with manipulated carbonate chemistry to alter dissolved inorganic carbon (DIC) concentration, and therefore total alkalinity (AT). We also investigate the intracellular pH of calcifying cells, photosynthesis, respiration and calcification rates under the same conditions. Our results show that despite constant pH in the surrounding seawater, pHCF is sensitive to shifts in carbonate chemistry associated with changes in [DIC] and [AT], revealing that seawater pH is not the sole driver of pHCF Notably, when we synthesize our results with published data, we identify linear relationships of pHCF with the seawater [DIC]/[H(+)] ratio, [AT]/ [H(+)] ratio and [[Formula: see text

  20. Ligand accessibility and bioactivity of a hormone–dendrimer conjugate depend on pH and pH history

    SciTech Connect

    Kim, Sung Hoon; Madak-Erdogan, Zeynep; Bae, Sung Chul; Carlson, Kathryn E.; Mayne, Christopher G.; Granick, Steve; Katzenellenbogen, Benita S.; Katzenellenbogen, John A.

    2015-07-17

    Estrogen conjugates with a polyamidoamine (PAMAM) dendrimer have shown remarkably selective regulation of the nongenomic actions of estrogens in target cells in this paper. In response to pH changes, however, these estrogen–dendrimer conjugates (EDCs) display a major morphological transition that alters the accessibility of the estrogen ligands that compromises the bioactivity of the EDC. A sharp break in dynamic behavior near pH 7 occurs for three different ligands on the surface of a PAMAM-G6 dendrimer: a fluorophore (tetramethylrhodamine [TMR]) and two estrogens (17α-ethynylestradiol and diphenolic acid). Collisional quenching and time-resolved fluorescence anisotropy experiments with TMR–PAMAM revealed high ligand shielding above pH 7 and low shielding below pH 7. Furthermore, when the pH was cycled from 8.5 (conditions of ligand–PAMAM conjugation) to 4.5 (e.g., endosome/lysosome) and through 6.5 (e.g., hypoxic environment) back to pH 8.5, the 17α-ethynylestradiol– and diphenolic acid–PAMAM conjugates experienced a dramatic, irreversible loss in cell stimulatory activity; dynamic NMR studies indicated that the hormonal ligands had become occluded within the more hydrophobic core of the PAMAM dendrimer. Thus, the active state of these estrogen–dendrimer conjugates appears to be metastable. Finally, this pH-dependent irreversible masking of activity is of considerable relevance to the design of drug conjugates with amine-bearing PAMAM dendrimers.

  1. EPA LABORATORIES IMPLEMENT EMS PROGRAM

    EPA Science Inventory

    This paper highlights the breadth and magnitude of carrying out an effective Environmental Management System (EMS) program at the U.S. EPA's research and development laboratories. Federal research laboratories have unique operating challenges compared to more centralized industr...

  2. PH5 for integrating and archiving different data types

    NASA Astrophysics Data System (ADS)

    Azevedo, Steve; Hess, Derick; Beaudoin, Bruce

    2016-04-01

    PH5 is IRIS PASSCAL's file organization of HDF5 used for seismic data. The extensibility and portability of HDF5 allows the PH5 format to evolve and operate on a variety of platforms and interfaces. To make PH5 even more flexible, the seismic metadata is separated from the time series data in order to achieve gains in performance as well as ease of use and to simplify user interaction. This separation affords easy updates to metadata after the data are archived without having to access waveform data. To date, PH5 is currently used for integrating and archiving active source, passive source, and onshore-offshore seismic data sets with the IRIS Data Management Center (DMC). Active development to make PH5 fully compatible with FDSN web services and deliver StationXML is near completion. We are also exploring the feasibility of utilizing QuakeML for active seismic source representation. The PH5 software suite, PIC KITCHEN, comprises in-field tools that include data ingestion (e.g. RefTek format, SEG-Y, and SEG-D), meta-data management tools including QC, and a waveform review tool. These tools enable building archive ready data in-field during active source experiments greatly decreasing the time to produce research ready data sets. Once archived, our online request page generates a unique web form and pre-populates much of it based on the metadata provided to it from the PH5 file. The data requester then can intuitively select the extraction parameters as well as data subsets they wish to receive (current output formats include SEG-Y, SAC, mseed). The web interface then passes this on to the PH5 processing tools to generate the requested seismic data, and e-mail the requester a link to the data set automatically as soon as the data are ready. PH5 file organization was originally designed to hold seismic time series data and meta-data from controlled source experiments using RefTek data loggers. The flexibility of HDF5 has enabled us to extend the use of PH5 in several

  3. Noninvasive Ph-telemetric Measurement of Gastrointestinal Function

    NASA Technical Reports Server (NTRS)

    Tietze, Karen J.

    1991-01-01

    The purpose of this study was to gain experience with and validate the Heidelberg pH-telemetric methodology in order to determine if the pH-telemetric methodology would be a useful noninvasive measure of gastrointestinal transit time for future ground-based and in-flight drug evaluation studies. The Heidelberg pH metering system is a noninvasive, nonradioactive telemetric system that, following oral ingestion, continuously measures intraluminal pH of the stomach, duodenum, small bowel, ileocecal junction, and large bowel. Gastrointestinal motility profiles were obtained in normal volunteers using the lactulose breath-hydrogen and Heidelberg pH metering techniques. All profiles were obtained in the morning after an overnight fast. Heidelberg pH profiles were obtained in the fasting and fed states; lactulose breath-hydrogen profiles were obtained after a standard breakfast. Mouth-to-cecum transit time was measured as the interval from administration of lactulose (30 ml; 20 g) to a sustained increase in breath-hydrogen of 10 ppm or more. Gastric emptying time was measured as the interval from the administration of the Heidelberg capsule to a sustained increase in pH of three units or more.

  4. The Production Rate and Employment of Ph.D. Astronomers

    NASA Astrophysics Data System (ADS)

    Metcalfe, Travis S.

    2008-02-01

    In an effort to encourage self-regulation of the astronomy job market, I examine the supply of, and demand for, astronomers over time. On the supply side, I document the production rate of Ph.D. astronomers from 1970 to 2006 using the UMI Dissertation Abstracts database, along with data from other independent sources. I compare the long-term trends in Ph.D. production with federal astronomy research funding over the same time period, and I demonstrate that additional funding is correlated with higher subsequent Ph.D. production. On the demand side, I monitor the changing patterns of employment using statistics about the number and types of jobs advertised in the AAS Job Register from 1984 to 2006. Finally, I assess the sustainability of the job market by normalizing this demand by the annual Ph.D. production. The most recent data suggest that there are now annual advertisements for about one postdoctoral job, half a faculty job, and half a research/support position for every new domestic Ph.D. recipient in astronomy and astrophysics. The average new astronomer might expect to hold up to 3 jobs before finding a steady position.

  5. Interfacial pH during mussel adhesive plaque formation

    PubMed Central

    Rodriguez, Nadine R. Martinez; Das, Saurabh; Kaufman, Yair; Israelachvili, Jacob N.; Waite, J. Herbert

    2015-01-01

    Mussel (Mytilus californianus) adhesion to marine surfaces involves an intricate and adaptive synergy of molecules and spatio-temporal processes. Although the molecules, such as mussel foot proteins (mfps), are well characterized, deposition details remain vague and speculative. Developing methods for the precise surveillance of conditions that apply during mfp deposition would aid both in understanding mussel adhesion and translating this adhesion into useful technologies. To probe the interfacial pH at which mussels buffer the local environment during mfp deposition, a lipid bilayer with tethered pH-sensitive fluorochromes was assembled on mica. The interfacial pH during foot contact with modified mica ranged from 2.2−3.3, which is well below the seawater pH of ~8. The acidic pH serves multiple functions: it limits mfp-Dopa oxidation, thereby enabling the catecholic functionalities to adsorb to surface oxides by H-bonding and metal ion coordination, and provides a solubility switch for mfps, most of which aggregate at pH ≥ 7-8. PMID:25875963

  6. Low pH increases the yield of exosome isolation.

    PubMed

    Ban, Jae-Jun; Lee, Mijung; Im, Wooseok; Kim, Manho

    2015-05-22

    Exosomes are the extracellular vesicles secreted by various cells. Exosomes mediate intercellular communication by delivering a variety of molecules between cells. Cancer cell derived exosomes seem to be related with tumor progression and metastasis. Tumor microenvironment is thought to be acidic and this low pH controls exosome physiology, leading to tumor progression. Despite the importance of microenvironmental pH on exosome, most of exosome studies have been performed without regard to pH. Therefore, the difference of exosome stability and yield of isolation by different pH need to be studied. In this research, we investigated the yield of total exosomal protein and RNA after incubation in acidic, neutral and alkaline conditioned medium. Representative exosome markers were investigated by western blot after incubation of exosomes in different pH. As a result, the concentrations of exosomal protein and nucleic acid were significantly increased after incubation in the acidic medium compared with neutral medium. The higher levels of exosome markers including CD9, CD63 and HSP70 were observed after incubation in an acidic environment. On the other hand, no exosomal protein, exosomal RNA and exosome markers have been detected after incubation in an alkaline condition. In summary, our results indicate that the acidic condition is the favorable environment for existence and isolation of exosomes.

  7. Intracellular pH and the Control of Multidrug Resistance

    NASA Astrophysics Data System (ADS)

    Simon, Sanford; Roy, Deborshi; Schindler, Melvin

    1994-02-01

    Many anticancer drugs are classified as either weak bases or molecules whose binding to cellular structures is pH dependent. Accumulation of these drugs within tumor cells should be affected by transmembrane pH gradients. Indeed, development of multidrug resistance (MDR) in tumor cells has been correlated with an alkaline shift of cytosolic pH. To examine the role of pH in drug partitioning, the distribution of two drugs, doxorubicin and daunomycin, was monitored in fibroblasts and myeloma cells. In both cell types the drugs rapidly accumulated within the cells. The highest concentrations were measured in the most acidic compartments-e.g., lysosomes. Modifying the cellular pH in drug-sensitive cells to mimic reported shifts in MDR caused an immediate change in the cellular drug concentration. Drug accumulation was enhanced by acidic shifts and reversed by alkaline shifts. All of these effects were rapid and reversible. These results demonstrate that the alkaline shift observed in MDR is sufficient to prevent the accumulation of chemotherapeutic drugs independent of active drug efflux.

  8. Intracellular pH and the control of multidrug resistance.

    PubMed Central

    Simon, S; Roy, D; Schindler, M

    1994-01-01

    Many anticancer drugs are classified as either weak bases or molecules whose binding to cellular structures is pH dependent. Accumulation of these drugs within tumor cells should be affected by transmembrane pH gradients. Indeed, development of multidrug resistance (MDR) in tumor cells has been correlated with an alkaline shift of cytosolic pH. To examine the role of pH in drug partitioning, the distribution of two drugs, doxorubicin and daunomycin, was monitored in fibroblasts and myeloma cells. In both cell types the drugs rapidly accumulated within the cells. The highest concentrations were measured in the most acidic compartments--e.g., lysosomes. Modifying the cellular pH in drug-sensitive cells to mimic reported shifts in MDR caused an immediate change in the cellular drug concentration. Drug accumulation was enhanced by acidic shifts and reversed by alkaline shifts. All of these effects were rapid and reversible. These results demonstrate that the alkaline shift observed in MDR is sufficient to prevent the accumulation of chemotherapeutic drugs independent of active drug efflux. Images PMID:8302842

  9. PhIN: A Protein Pharmacology Interaction Network Database

    PubMed Central

    Wang, Z; Li, J; Dang, R; Liang, L; Lin, J

    2015-01-01

    Network pharmacology is a new and hot concept in drug discovery for its ability to investigate the complexity of polypharmacology, and becomes more and more important in drug development. Here we report a protein pharmacology interaction network database (PhIN), aiming to assist multitarget drug discovery by providing comprehensive and flexible network pharmacology analysis. Overall, PhIN contains 1,126,060 target–target interaction pairs in terms of shared compounds and 3,428,020 pairs in terms of shared scaffolds, which involve 12,419,700 activity data, 9,414 targets, 314 viral targets, 652 pathways, 1,359,400 compounds, and 309,556 scaffolds. Using PhIN, users can obtain interacting target networks within or across human pathways, between human and virus, by defining the number of shared compounds or scaffolds under an activity cutoff. We expect PhIN to be a useful tool for multitarget drug development. PhIN is freely available at http://cadd.pharmacy.nankai.edu.cn/phin/. PMID:26225242

  10. Ocean Acidification: Euphausia Pacifica's Response to Decreasing pH

    NASA Astrophysics Data System (ADS)

    Weber, H. N.; Cooper, H.

    2014-12-01

    The increasing rate of CO2 accumulating in Earth's oceans creates a threat to organisms that can lead to disturbances in their reproduction, survival and growth. Euphausia pacifica is the dominant species of krill in Monterey Bay, CA, and a keystone species in the bay's food web. Previous work on the effects of ocean acidification on the survival, growth and molting of E. pacifica have shown they are fairly tolerant to increased CO2 concentrations. However, less is known about energy costs associated with maintaining their internal pH levels which could affect food consumption, swimming behavior or growth activity. We hypothesized that krill exposed to high CO2 will increase their feeding rate on local species of phytoplankton to account for increased energy costs of pH buffering activity. We exposed experimental E. pacifica to waters of pH 7.6 (the expected pH surface waters in year 2100), and pH 8.0 (control) periods.test for acclimation or longer term stress. Feeding rates were calculated as changes in phytoplankton counts over 24 hours of feeding using Frost's equations (Frost 1972). Understanding the way E. pacifica is affected by ocean acidification is important because of the role they play as the primary food source for a variety of predators necessary to maintain the Pacific's ecology.

  11. Reduction of dehydroascorbic acid at low pH.

    PubMed

    Wechtersbach, Luka; Cigić, Blaz

    2007-08-01

    Ascorbic acid and dehydroascorbic acid are unstable in aqueous solution in the presence of copper and iron ions, causing problems in the routine analysis of vitamin C. Their stability can be improved by lowering the pH below 2, preferably with metaphosphoric acid. Dehydroascorbic acid, an oxidised form of vitamin C, gives a relatively low response on the majority of chromatographic detectors, and is therefore routinely determined as the increase of ascorbic acid formed after reduction. The reduction step is routinely performed at a pH that is suboptimal for the stability of both forms. In this paper, the reduction of dehydroascorbic acid with tris-[2-carboxyethyl] phosphine (TCEP) at pH below 2 is evaluated. Dehydroascorbic acid is fully reduced with TCEP in metaphosphoric acid in less than 20 min, and yields of ascorbic acid are the same as at higher pH. TCEP and ascorbic acid formed by reduction, are more stable in metaphosphoric acid than in acetate or citrate buffers at pH 5, in the presence of redox active copper ions. The simple experimental procedure and low probability of artefacts are major benefits of this method, over those currently applied in a routine assay of vitamin C, performed on large number of samples.

  12. Kinetics of biological perchlorate reduction and pH effect.

    PubMed

    Wang, Chao; Lippincott, Lee; Meng, Xiaoguang

    2008-05-01

    Batch experiments were conducted to investigate the kinetics of perchlorate reduction by heterotrophic and mixed perchlorate-reducing bacteria. Substrate-utilizing and cellular maintenance models were employed to fit the experimental data for microbial perchlorate reduction. The half saturation constant, K(s), obtained in this study was below 0.1mg/L, which indicated that perchlorate-reducing bacteria are effective at utilizing low concentrations of perchlorate. The effect of pH on the kinetics of microbial perchlorate reduction was also studied. Perchlorate reduction occurred throughout the pH range from 5.0 to 9.0. Nevertheless, the rates of perchlorate removal by a unit mass of bacteria were significantly different at various pHs with a maximum rate at pH 7.0. The variation of q(max) with pH was described well with a Gaussian peak equation. This equation is expected to be applicable for practical purposes when pH effects need to be considered.

  13. pH responsive graft copolymers of chitosan.

    PubMed

    Yilmaz, Elvan; Yalinca, Zulal; Yahya, Kovan; Sirotina, Uliana

    2016-09-01

    Grafting suitable polymers onto chitosan can produce cationic or polyampholyte polymers or hydrogels that are potential smart biomedical materials. Chitosan-graft-[poly(diethylamino)ethyl methacrylate] has been prepared in three different physical forms as linear free chains in solution, chemical gels crosslinked with glutaraldehyde, and poly(diethylamino)ethyl methacrylate] grafted onto chitosan tripolyphosphate gel beads. In addition to chemical structure, the graft copolymers were characterized with respect to their dissolution and swelling behavior in aqueous solution. It has been established that solubility of the products is controlled by the grafting yield. While pH sensitive polymers, which collapse at a given pH value are obtained at lower grafting yields, hydrogels form at higher grafting yields with pH responsive swelling behavior. Glutaraldehyde crosslinked chitosan-graft-[poly(diethylamino)ethyl methacrylate] gels and chitosan tripolyphosphate gel beads grafted with poly[(diethylamino)ethyl methacrylate] exhibit pH sensitive swelling with highest equilibrium swelling capacity at pH=1.2.

  14. Near-infrared noninvasive spectroscopic determination of pH

    DOEpatents

    Alam, Mary K.; Robinson, Mark R.

    1998-08-11

    Methods and apparatus for, preferably, determining noninvasively and in vitro pH in a human. The non-invasive method includes the steps of: generating light at three or more different wavelengths in the range of 1000 nm to 2500 nm; irradiating blood containing tissue; measuring the intensities of the wavelengths emerging from the blood containing tissue to obtain a set of at least three spectral intensities v. wavelengths; and determining the unknown values of pH. The determination of pH is made by using measured intensities at wavelengths that exhibit change in absorbance due to histidine titration. Histidine absorbance changes are due to titration by hydrogen ions. The determination of the unknown pH values is performed by at least one multivariate algorithm using two or more variables and at least one calibration model. The determined pH values are within the physiological ranges observed in blood containing tissue. The apparatus includes a tissue positioning device, a source, at least one detector, electronics, a microprocessor, memory, and apparatus for indicating the determined values.

  15. Interfacial pH during mussel adhesive plaque formation.

    PubMed

    Martinez Rodriguez, Nadine R; Das, Saurabh; Kaufman, Yair; Israelachvili, Jacob N; Waite, J Herbert

    2015-01-01

    Mussel (Mytilus californianus) adhesion to marine surfaces involves an intricate and adaptive synergy of molecules and spatio-temporal processes. Although the molecules, such as mussel foot proteins (mfps), are well characterized, deposition details remain vague and speculative. Developing methods for the precise surveillance of conditions that apply during mfp deposition would aid both in understanding mussel adhesion and translating this adhesion into useful technologies. To probe the interfacial pH at which mussels buffer the local environment during mfp deposition, a lipid bilayer with tethered pH-sensitive fluorochromes was assembled on mica. The interfacial pH during foot contact with modified mica ranged from 2.2 to 3.3, which is well below the seawater pH of ~ 8. The acidic pH serves multiple functions: it limits mfp-Dopa oxidation, thereby enabling the catecholic functionalities to adsorb to surface oxides by H-bonding and metal ion coordination, and provides a solubility switch for mfps, most of which aggregate at pH ≥ 7-8.

  16. Busca de estruturas em grandes escalas em altos redshifts

    NASA Astrophysics Data System (ADS)

    Boris, N. V.; Sodrã©, L., Jr.; Cypriano, E.

    2003-08-01

    A busca por estruturas em grandes escalas (aglomerados de galáxias, por exemplo) é um ativo tópico de pesquisas hoje em dia, pois a detecção de um único aglomerado em altos redshifts pode por vínculos fortes sobre os modelos cosmológicos. Neste projeto estamos fazendo uma busca de estruturas distantes em campos contendo pares de quasares próximos entre si em z Â3 0.9. Os pares de quasares foram extraídos do catálogo de Véron-Cetty & Véron (2001) e estão sendo observados com os telescópios: 2,2m da University of Hawaii (UH), 2,5m do Observatório de Las Campanas e com o GEMINI. Apresentamos aqui a análise preliminar de um par de quasares observado nos filtros i'(7800 Å) e z'(9500 Å) com o GEMINI. A cor (i'-z') mostrou-se útil para detectar objetos "early-type" em redshifts menores que 1.1. No estudo do par 131046+0006/J131055+0008, com redshift ~ 0.9, o uso deste método possibilitou a detecção de sete objetos candidatos a galáxias "early-type". Num mapa da distribuição projetada dos objetos para 22 < i' < 25 observou-se que estas galáxias estão localizadas próximas a um dos quasares e há indícios de que estejam aglomeradas dentro de um área de ~ 6 arcmin2. Se esse for o caso, estes objetos seriam membros de uma estrutura em grande escala. Um outro argumento em favor dessa hipótese é que eles obedecem uma relação do tipo Kormendy (raio equivalente X brilho superficial dentro desse raio), como a apresentada pelas galáxias elípticas em z = 0.

  17. The pH dependent Raman spectroscopic study of caffeine

    NASA Astrophysics Data System (ADS)

    Kang, Jian; Gu, Huaimin; Zhong, Liang; Hu, Yongjun; Liu, Fang

    2011-02-01

    First of all the surface enhanced Raman spectroscopy (SERS) and normal Raman spectra of caffeine aqueous solution were obtained at different pH values. In order to obtain the detailed vibrational assignments of the Raman spectroscopy, the geometry of caffeine molecule was optimized by density functional theory (DFT) calculation. By comparing the SERS of caffeine with its normal spectra at different pH values; it is concluded that pH value can dramatically affect the SERS of caffeine, but barely affect the normal Raman spectrum of caffeine aqueous solution. It can essentially affect the reorientation of caffeine molecule to the Ag colloid surface, but cannot impact the vibration of functional groups and chemical bonds in caffeine molecule.

  18. Designing pH induced fold switch in proteins.

    PubMed

    Baruah, Anupaul; Biswas, Parbati

    2015-05-14

    This work investigates the computational design of a pH induced protein fold switch based on a self-consistent mean-field approach by identifying the ensemble averaged characteristics of sequences that encode a fold switch. The primary challenge to balance the alternative sets of interactions present in both target structures is overcome by simultaneously optimizing two foldability criteria corresponding to two target structures. The change in pH is modeled by altering the residual charge on the amino acids. The energy landscape of the fold switch protein is found to be double funneled. The fold switch sequences stabilize the interactions of the sites with similar relative surface accessibility in both target structures. Fold switch sequences have low sequence complexity and hence lower sequence entropy. The pH induced fold switch is mediated by attractive electrostatic interactions rather than hydrophobic-hydrophobic contacts. This study may provide valuable insights to the design of fold switch proteins.

  19. Stabilization of Mercury in High pH Tank Sludges

    SciTech Connect

    Spence, R.; Barton, J.

    2003-02-24

    DOE complex contains many tank sludges contaminated with mercury. The high pH of these tank sludges typically fails to stabilize the mercury, resulting in these radioactive wastes also being characteristically hazardous or mixed waste. The traditional treatment for soluble inorganic mercury species is precipitation as insoluble mercuric sulfide. Sulfide treatment and a commercial mercury-stabilizing product were tested on surrogate sludges at various alkaline pH values. Neither the sulfide nor the commercial product stabilized the mercury sufficiently at the high pH of the tank sludges to pass the Toxicity Characteristic Leach Procedure (TCLP) treatment standards of the Resource Conservation and Recovery Act (RCRA). The commercial product also failed to stabilize the mercury in samples of the actual tank sludges.

  20. PH and Electrochemical Responsive Materials for Corrosion Smart Coating Applications

    NASA Technical Reports Server (NTRS)

    Li, Wenyan; Calle, Luz M.

    2008-01-01

    Corrosion is a costly issue for military operations and civil industries. While most corrosion initiates from localized corrosion form, such as pitting, failure directly caused by localized corrosion is the most dangerous kind, because it is difficult to anticipate and prevent, occurs very suddenly and can be catastrophic. One way of preventing these failures is with a coating that can detect and heal localized corrosion. pH and other electrochemical changes are often associated with localized corrosion, so it is expected that materials that are pH or otherwise electrochemical responsive can be used to detect and control corrosion. This paper will review various pH and electrochemical responsive materials and their potential applications in corrosion smart coatings. Current research results in this field will also be reported.

  1. IMPACT OF WATER PH ON ZEBRA MUSSEL MORTALITY

    SciTech Connect

    Daniel P. Molloy

    2002-10-15

    The experiments conducted this past quarter have suggested that the bacterium Pseudomonas fluorescens strain CL0145A is effective at killing zebra mussels throughout the entire range of pH values tested (7.2 to 8.6). Highest mortality was achieved at pH values characteristic of preferred zebra mussel waterbodies, i.e., hard waters with a range of 7.8 to 8.6. In all water types tested, however, ranging from very soft to very hard, considerable mussel kill was achieved (83 to 99% mean mortality), suggesting that regardless of the pH or hardness of the treated water, significant mussel kill can be achieved upon treatment with P. fluorescens strain CL0145A. These results further support the concept that this bacterium has significant potential for use as a zebra mussel control agent in power plant pipes receiving waters with a wide range of physical and chemical characteristics.

  2. Photonic porous silicon as a pH sensor.

    PubMed

    Pace, Stephanie; Vasani, Roshan B; Zhao, Wei; Perrier, Sébastien; Voelcker, Nicolas H

    2014-01-01

    Chronic wounds do not heal within 3 months, and during the lengthy healing process, the wound is invariably exposed to bacteria, which can colonize the wound bed and form biofilms. This alters the wound metabolism and brings about a change of pH. In this work, porous silicon photonic films were coated with the pH-responsive polymer poly(2-diethylaminoethyl acrylate). We demonstrated that the pH-responsive polymer deposited on the surface of the photonic film acts as a barrier to prevent water from penetrating inside the porous matrix at neutral pH. Moreover, the device demonstrated optical pH sensing capability visible by the unaided eye.

  3. Photonic porous silicon as a pH sensor

    NASA Astrophysics Data System (ADS)

    Pace, Stephanie; Vasani, Roshan B.; Zhao, Wei; Perrier, Sébastien; Voelcker, Nicolas H.

    2014-08-01

    Chronic wounds do not heal within 3 months, and during the lengthy healing process, the wound is invariably exposed to bacteria, which can colonize the wound bed and form biofilms. This alters the wound metabolism and brings about a change of pH. In this work, porous silicon photonic films were coated with the pH-responsive polymer poly(2-diethylaminoethyl acrylate). We demonstrated that the pH-responsive polymer deposited on the surface of the photonic film acts as a barrier to prevent water from penetrating inside the porous matrix at neutral pH. Moreover, the device demonstrated optical pH sensing capability visible by the unaided eye.

  4. Controllable dissociations of PH3 molecules on Si(001)

    NASA Astrophysics Data System (ADS)

    Liu, Qin; Lei, Yanhua; Shao, Xiji; Ming, Fangfei; Xu, Hu; Wang, Kedong; Xiao, Xudong

    2016-04-01

    We demonstrate for the first time to our knowledge that controllable dissociation of PH3 adsorption products PH x (x = 2, 1) can be realized by STM (scanning tunneling microscope) manipulation techniques at room temperature. Five dissociative products and their geometric structures are identified via combining STM experiments and first-principle calculations and simulations. In total we realize nine kinds of controllable dissociations by applying a voltage pulse among the PH3-related structures on Si(001). The dissociation rates of the five most common reactions are measured by the I-t spectrum method as a function of voltage. The suddenly increased dissociation rate at 3.3 V indicates a transition from multivibrational excitation to single-step excitation induced by inelastic tunneling electrons. Our studies prove that selectively breaking the chemical bonds of a single molecule on semiconductor surface by STM manipulation technique is feasible.

  5. An analysis of Ph.D. examiners' reports in engineering

    NASA Astrophysics Data System (ADS)

    Prieto, Elena; Holbrook, Allyson; Bourke, Sid

    2016-03-01

    In recent years, there have been increasing calls for an overall transformation of the nature of engineering Ph.D. programs and the way theses are assessed. There exists a need to understand the examination process to ensure the best quality outcome for candidates in engineering. The work we present in this paper uses data collected between 2003 and 2010 for a total of 1220 Australian Ph.D. theses by analysing examiner reports. Our analysis indicates that Ph.D. theses in engineering, N = 106, differ considerably from those in other fields in areas such as gender of candidates and examiners and the examiners' geographical location. We also found that assessment areas such as significance and contribution of the thesis, publications arising from the thesis, breadth, depth and recency of the literature review and communication and editorial correctness are areas in which the proportion of text of engineering examiners' comments differs significantly from other fields.

  6. Nanocrystalline hydroxyapatite prepared under various pH conditions.

    PubMed

    Palanivelu, R; Mary Saral, A; Ruban Kumar, A

    2014-10-15

    Hydroxyapatite (HAP) has sovereign biomedical application due to its excellent biocompatibility, chemical and crystallographic similitude with natural human bone. In this present work, we discussed about the role of pH in the synthesis of calcium phosphate compound using calcium nitrate tetrahydrate and di-ammonium hydrogen phosphate as starting materials by chemical precipitation method assisted with ultrasonic irradiation technique. 5% polyethylene glycol (PEG600) is added along with the precursors under various pH condition of 7, 9 and 11 respectively. The functional group analysis, crystallized size and fraction of crystallized size are confirmed using Fourier Transformation Infra-Red spectroscopy and X-ray diffraction pattern. Morphological observations are done by scanning electron microscope. The results revealed the presence of nanocrystalline hydroxyapatite at pH above 9.

  7. Mid-Career PhD Physicists: Academia & Beyond

    NASA Astrophysics Data System (ADS)

    White, Susan

    2017-01-01

    What jobs do mid-career PhD physicists hold? In a first-ever study, we collected data in 2011 from over 1,500 physics PhD recipients from the classes of 1996, 1997, 2000, and 2001. About 45% of the physics PhD recipients in these classes immediately took jobs that were not temporary, and over 40% accepted postdocs. How does taking a postdoc affect mid-career employment? What is the relationship between first job (after any postdocs) and mid-career employment? How do physicists' actual jobs compare with what they thought they would be doing when they graduated? Using our initial employment and mid-career data, I will answer these questions and more.

  8. Bicarbonate Increases Tumor pH and Inhibits Spontaneous Metastases

    PubMed Central

    Robey, Ian F.; Baggett, Brenda K.; Kirkpatrick, Nathaniel D.; Roe, Denise J.; Dosescu, Julie; Sloane, Bonnie F.; Hashim, Arig Ibrahim; Morse, David L.; Raghunand, Natarajan; Gatenby, Robert A.; Gillies, Robert J.

    2010-01-01

    The external pH of solid tumors is acidic as a consequence of increased metabolism of glucose and poor perfusion. Acid pH has been shown to stimulate tumor cell invasion and metastasis in vitro and in cells before tail vein injection in vivo. The present study investigates whether inhibition of this tumor acidity will reduce the incidence of in vivo metastases. Here, we show that oral NaHCO3 selectively increased the pH of tumors and reduced the formation of spontaneous metastases in mouse models of metastatic breast cancer. This treatment regimen was shown to significantly increase the extracellular pH, but not the intracellular pH, of tumors by 31P magnetic resonance spectroscopy and the export of acid from growing tumors by fluorescence microscopy of tumors grown in window chambers. NaHCO3 therapy also reduced the rate of lymph node involvement, yet did not affect the levels of circulating tumor cells, suggesting that reduced organ metastases were not due to increased intravasation. In contrast, NaHCO3 therapy significantly reduced the formation of hepatic metastases following intrasplenic injection, suggesting that it did inhibit extravasation and colonization. In tail vein injections of alternative cancer models, bicarbonate had mixed results, inhibiting the formation of metastases from PC3M prostate cancer cells, but not those of B16 melanoma. Although the mechanism of this therapy is not known with certainty, low pH was shown to increase the release of active cathepsin B, an important matrix remodeling protease. PMID:19276390

  9. Harvard College Observatory: Shapley's Factory for PhD Degrees?

    NASA Astrophysics Data System (ADS)

    Welther, B. L.

    2000-12-01

    When Harlow Shapley assumed the Directorship of Harvard College Observatory in 1921, there was no program in place there to train the next generation of astronomers. In 1923, using the Pickering Fund for women assistants, Shapley hired a young English woman, Cecilia Payne, to work on stellar spectra. Just two short years later, Payne completed her research and wrote a celebrated thesis on stellar atmospheres. Because Harvard University was not prepared to confer a PhD degree on a woman at that time, Payne presented her thesis to Radcliffe College. Thus, in 1925 she became the first person to receive a PhD in astronomy for a research project at HCO. By 1933, a PhD in Astronomy had been conferred on eight graduate students who had undertaken research projects at HCO: four men who received their degree from Harvard, and four women, from Radcliffe. In subsequent years, however, the equal distribution of degrees for men and women quickly changed. When the 30th degree was bestowed in 1943, only 10 of the candidates were women. By 1955, when the 60th degree was conferred, only 14 women had received a PhD. In just two decades, then, the ratio of women astronomers had steadily dropped from a solid 50% at the height of the Shapley era to slightly less than 25% at his retirement. Also, until the mid-1960s, the women astronomers still had to apply to Radcliffe for their PhD degrees. This paper will briefly examine the funding and research topics of some of the HCO PhD candidates in the Shapley Era (1921-1955). It will also highlight some of their subsequent contributions to 20th-century American Astronomy.

  10. pH sensitive quantum dot-anthraquinone nanoconjugates

    NASA Astrophysics Data System (ADS)

    Ruedas-Rama, Maria Jose; Hall, Elizabeth A. H.

    2014-05-01

    Semiconductor quantum dots (QDs) have been shown to be highly sensitive to electron or charge transfer processes, which may alter their optical properties. This feature can be exploited for different sensing applications. Here, we demonstrate that QD-anthraquinone conjugates can function as electron transfer-based pH nanosensors. The attachment of the anthraquinones on the surface of QDs results in the reduction of electron hole recombination, and therefore a quenching of the photoluminescence intensity. For some anthraquinone derivatives tested, the quenching mechanism is simply caused by an electron transfer process from QDs to the anthraquinone, functioning as an electron acceptor. For others, electron transfer and energy transfer (FRET) processes were found. A detailed analysis of the quenching processes for CdSe/ZnS QD of two different sizes is presented. The photoluminescence quenching phenomenon of QDs is consistent with the pH sensitive anthraquinone redox chemistry. The resultant family of pH nanosensors shows pKa ranging ˜5-8, being ideal for applications of pH determination in physiological samples like blood or serum, for intracellular pH determination, and for more acidic cellular compartments such as endosomes and lysosomes. The nanosensors showed high selectivity towards many metal cations, including the most physiologically important cations which exist at high concentration in living cells. The reversibility of the proposed systems was also demonstrated. The nanosensors were applied in the determination of pH in samples mimicking the intracellular environment. Finally, the possibility of incorporating a reference QD to achieve quantitative ratiometric measurements was investigated.

  11. Bicarbonate increases tumor pH and inhibits spontaneous metastases.

    PubMed

    Robey, Ian F; Baggett, Brenda K; Kirkpatrick, Nathaniel D; Roe, Denise J; Dosescu, Julie; Sloane, Bonnie F; Hashim, Arig Ibrahim; Morse, David L; Raghunand, Natarajan; Gatenby, Robert A; Gillies, Robert J

    2009-03-15

    The external pH of solid tumors is acidic as a consequence of increased metabolism of glucose and poor perfusion. Acid pH has been shown to stimulate tumor cell invasion and metastasis in vitro and in cells before tail vein injection in vivo. The present study investigates whether inhibition of this tumor acidity will reduce the incidence of in vivo metastases. Here, we show that oral NaHCO(3) selectively increased the pH of tumors and reduced the formation of spontaneous metastases in mouse models of metastatic breast cancer. This treatment regimen was shown to significantly increase the extracellular pH, but not the intracellular pH, of tumors by (31)P magnetic resonance spectroscopy and the export of acid from growing tumors by fluorescence microscopy of tumors grown in window chambers. NaHCO(3) therapy also reduced the rate of lymph node involvement, yet did not affect the levels of circulating tumor cells, suggesting that reduced organ metastases were not due to increased intravasation. In contrast, NaHCO(3) therapy significantly reduced the formation of hepatic metastases following intrasplenic injection, suggesting that it did inhibit extravasation and colonization. In tail vein injections of alternative cancer models, bicarbonate had mixed results, inhibiting the formation of metastases from PC3M prostate cancer cells, but not those of B16 melanoma. Although the mechanism of this therapy is not known with certainty, low pH was shown to increase the release of active cathepsin B, an important matrix remodeling protease.

  12. Manganese toxicity to fungi: influence of pH

    SciTech Connect

    Babich, H.; Stotzky, G.

    1981-10-01

    The effects of Mn on mycelial proliferation of fungi and the effect of pH on Mn toxicity were evaluated. Results indicated that the fungi exhibited wide differences in their sensitivities to Mn. Incipient inhibition (i.e., the level of Mn at which growth inhibition was noted initially, P < 0.05) for Scopulariopsis brevicaulis and Aspergillus giganteus occurred at 100 ppM Mn; for Rhizopus stolonifer, Arthrobotrys conoides, Aspergillus niger, Aspergillus flavus, Trichoderma viride, and Penicillium vermiculatum at 500 ppM Mn; for Cephalosporium sp. at 1000 ppM Mn; and for Gliocladium sp. at 1000 to 1500 ppM Mn; growth of Aspergillus clavatus was not inhibited even at 2000 ppM Mn. No growth of S. brevicaulis occurred at 500 ppM Mn and of R. stolonifer at 1500 ppM Mn. The levels of Mn causing incipient and/or total inhibition of mycelial growth of the fungi studied were comparable to the levels reported to inhibit mycelial proliferation of some phylloplane fungi. Only A. conoides showed significant (P < 0.5) stimulation of mycelial growth by Mn; 10, 50, and 100 ppM Mn increased growth rates over control (0 ppM Mn) values. There was no consistent trend in the effect of pH on Mn toxicity to the fungi. However, each fungus showed a definitive response to Mn at the different pH levels. Thus, increasing the pH from 5.5 to 8.5 did not significantly affect the toxicity of Mn to Gliocladium sp., P. vermiculatum, or A. niger. The toxicity of Mn to R. stolonifer and T. viride was not different at pH 5.5 and 6.5, but increasing the pH to 7.5 or 8.5 significantly enhanced the toxicity.

  13. Cytoplasmic pH mediates pH taxis and weak-acid repellent taxis of bacteria.

    PubMed

    Kihara, M; Macnab, R M

    1981-03-01

    Bacteria migrate away from an acid pH and from a number of chemicals, including organic acids such as acetate; the basis for detection of these environmental cues has not been demonstrated. Membrane-permeant weak acids caused prolonged tumbling when added to Salmonella sp. or Escherichia coli cells at pH 5.5. Tethered Salmonella cells went from a prestimulus behavior of 14% clockwise rotation to 80% clockwise rotation when 40 mM acetate was added and remained this way for more than 30 min. A low external pH in the absence of weak acid did not markedly affect steady-state tumbling frequency. Among the weak acids tested, the rank for acidity (salicylate greater than benzoate greater than acetate greater than 5,5-dimethyl-2,4-oxazolidinedione) was the same as the rank for the ability to collapse the transmembrane pH gradient and to cause tumbling. At pH 7.0, the tumbling responses caused by the weak acids were much briefer. Indole, a non-weak-acid repellent, did not cause prolonged tumbling at low pH. Two chemotaxis mutants (a Salmonella mutant defective in the chemotaxis methylesterase and an E. coli mutant defective in the methyl-accepting protein in MCP I) showed inverse responses of enhanced counterclockwise rotation in the first 1 min after acetate addition. The latter mutant had been found previously to be defective in the sensing of gradients of extracellular pH and (at neutral pH) of acetate. We conclude (i) that taxes away from acid pH and membrane-permeant weak acids are both mediated by a pH-sensitive component located either in the cytoplasm or on the cytoplasmic side of the membrane, rather than by an external receptor (as in the case of the attractants), and (ii) that both of these taxes involve components of the chemotaxis methylation system, at least in the early phase of the response.

  14. Doping of germanium nanowires grown in presence of PH3

    NASA Astrophysics Data System (ADS)

    Tutuc, E.; Chu, J. O.; Ott, J. A.; Guha, S.

    2006-12-01

    The authors study the Au-catalyzed chemical vapor growth of germanium (Ge) nanowires in the presence of phosphine (PH3), used as a dopant precursor. The device characteristics of the ensuing nanowire field effect transistors (FETs) indicate n-type, highly doped nanowires. Using a combination of different nanowire growth sequences and their FET characteristics, the authors determine that phosphorus incorporates predominately via the conformal growth, which accompanies the acicular, nanowire growth. As such, the Ge nanowires grown in the presence of PH3 contain a phosphorus doped shell and an undoped core. The authors determine the doping level in the shell to be ≃(1-4)×1019cm-3.

  15. Physiological carbon dioxide, bicarbonate, and pH sensing

    PubMed Central

    Tresguerres, Martin; Buck, Jochen

    2010-01-01

    In biological systems, carbon dioxide exists in equilibrium with bicarbonate and protons. The individual components of this equilibrium (i.e., CO2, HCO3−, and H+), which must be sensed to be able to maintain cellular and organismal pH, also function as signals to modulate multiple physiological functions. Yet, the molecular sensors for CO2/HCO3−/pH remained unknown until recently. Here, we review recent progress in delineating molecular and cellular mechanisms for sensing CO2, HCO3−, and pH. PMID:20683624

  16. pH control in biological systems using calcium carbonate.

    PubMed

    Salek, S S; van Turnhout, A G; Kleerebezem, R; van Loosdrecht, M C M

    2015-05-01

    Due to its abundance, calcium carbonate (CaCO3) has high potentials as a source of alkalinity for biotechnological applications. The application of CaCO3 in biological systems as neutralizing agent is, however, limited due to potential difficulties in controlling the pH. The objective of the present study was to determine the dominant processes that control the pH in an acid-forming microbial process in the presence of CaCO3. To achieve that, a mathematical model was made with a minimum set of kinetically controlled and equilibrium reactions that was able to reproduce the experimental data of a batch fermentation experiment using finely powdered CaCO3. In the model, thermodynamic equilibrium was assumed for all speciation, complexation and precipitation reactions whereas, rate limited reactions were included for the biological fatty acid production, the mass transfer of CO2 from the liquid phase to the gas phase and the convective transport of CO2 out of the gas phase. The estimated pH-pattern strongly resembled the measured pH, suggesting that the chosen set of kinetically controlled and equilibrium reactions were establishing the experimental pH. A detailed analysis of the reaction system with the aid of the model revealed that the pH establishment was most sensitive to four factors: the mass transfer rate of CO2 to the gas phase, the biological acid production rate, the partial pressure of CO2 and the Ca(+2) concentration in the solution. Individual influences of these factors on the pH were investigated by extrapolating the model to a continuously stirred-tank reactor (CSTR) case. This case study indicates how the pH of a commonly used continuous biotechnological process could be manipulated and adjusted by altering these four factors. Achieving a better insight of the processes controlling the pH of a biological system using CaCO3 as its neutralizing agent can result in broader applications of CaCO3 in biotechnological industries.

  17. Developing imidazoles as CEST MRI pH sensors

    PubMed Central

    Yang, Xing; Song, Xiaolei; Banerjee, Sangeeta Ray; Li, Yuguo; Byun, Youngjoo; Liu, Guanshu; Bhujwalla, Zaver M.; Pomper, Martin G.; McMahon, Michael T.

    2016-01-01

    A series of intra-molecular hydrogen bonded imidazoles and related heterocyclic compounds were screened for their N–H chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) contrast properties. Of the compounds, imidazole-4,5-dicarboxamides (I45DCs) were found to provide the strongest contrast, with the contrast produced at a large chemical shift from water (7.8 ppm) and strongly dependent on pH. We have tested several probes based on this scaffold, and demonstrated that these probes could be applied for in vivo detection of kidney pH after intravenous administration. PMID:27071959

  18. Physiological carbon dioxide, bicarbonate, and pH sensing.

    PubMed

    Tresguerres, Martin; Buck, Jochen; Levin, Lonny R

    2010-11-01

    In biological systems, carbon dioxide exists in equilibrium with bicarbonate and protons. The individual components of this equilibrium (i.e., CO₂, HCO₃⁻, and H(+)), which must be sensed to be able to maintain cellular and organismal pH, also function as signals to modulate multiple physiological functions. Yet, the molecular sensors for CO₂/HCO₃⁻/pH remained unknown until recently. Here, we review recent progress in delineating molecular and cellular mechanisms for sensing CO₂, HCO₃⁻, and pH.

  19. Measurement and control of pH in hydrothermal solutions

    SciTech Connect

    Wesolowski, D.J.; Palmer, D.A.; Mesmer, R.E.

    1995-12-31

    Hydrogen-electrode concentration cells with liquid junction are routinely used to measure the pH of aqueous solutions from 0 to 300 C. Results include the dissociation constants of common acids and bases and the hydrolysis and complexation of metal ions in aqueous electrolytes over a wide range of salinities. Recently, we have utilized these cells to examine the sorption of H{sup +} on mineral surfaces, the solubility of minerals with continuous in situ pH measurement, and the thermal decompositon rates of organic acids.

  20. Measuring Phagosomal pH by Fluorescence Microscopy.

    PubMed

    Canton, Johnathan; Grinstein, Sergio

    2017-01-01

    Dual wavelength ratiometric imaging has become a powerful tool for the study of pH in intracellular compartments. It allows for the dynamic imaging of live cells while accounting for changes in the focal plane, differential loading of the fluorescent probe, and photobleaching caused by repeated image acquisitions. Ratiometric microscopic imaging has the added advantage over whole population methods of being able to resolve individual cells and even individual organelles. In this chapter we provide a detailed discussion of the basic principles of ratiometric imaging and its application to the measurement of phagosomal pH, including probe selection, the necessary instrumentation, and calibration methods.

  1. Metal/Metal Oxide Differential Electrode pH Sensors

    NASA Technical Reports Server (NTRS)

    West, William; Buehler, Martin; Keymeulen, Didier

    2007-01-01

    Solid-state electrochemical sensors for measuring the degrees of acidity or alkalinity (in terms of pH values) of liquid solutions are being developed. These sensors are intended to supplant older electrochemical pH sensors that include glass electrode structures and reference solutions. The older sensors are fragile and subject to drift. The present developmental solid-state sensors are more rugged and are expected to be usable in harsh environments. The present sensors are based on a differential-electrode measurement principle. Each sensor includes two electrodes, made of different materials, in equilibrium with the solution of interest.

  2. Alkaline pH Homeostasis in Bacteria: New Insights

    PubMed Central

    Padan, Etana; Bibi, Eitan; Ito, Masahiro; Krulwich, Terry A.

    2011-01-01

    The capacity of bacteria to survive and grow at alkaline pH values is of widespread importance in the epidemiology of pathogenic bacteria, in remediation and industrial settings, as well as in marine, plant-associated and extremely alkaline ecological niches. Alkali-tolerance and alkaliphily, in turn, strongly depend upon mechanisms for alkaline pH homeostasis, as shown in pH shift experiments and growth experiments in chemostats at different external pH values. Transcriptome and proteome analyses have recently complemented physiological and genetic studies, revealing numerous adaptations that contribute to alkaline pH homeostasis. These include elevated levels of transporters and enzymes that promote proton capture and retention (e.g. the ATP synthase and monovalent cation/proton antiporters), metabolic changes that lead to increased acid production, and changes in the cell surface layers that contribute to cytoplasmic proton retention. Targeted studies over the past decade have followed up the long-recognized importance of monovalent cations in active pH homeostasis. These studies show the centrality of monovalent cation/proton antiporters in this process while microbial genomics provides information about the constellation of such antiporters in individual strains. A comprehensive phylogenetic analysis of both eukaryotic and prokaryotic genome databases has identified orthologes from bacteria to humans that allow better understanding of the specific functions and physiological roles of the antiporters. Detailed information about the properties of multiple antiporters in individual strains is starting to explain how specific monovalent cation/proton antiporters play dominant roles in alkaline pH homeostasis in cells that have several additional antiporters catalyzing ostensibly similar reactions. New insights into the pH-dependent Na+/H+ antiporter NhaA that plays an important role in Escherichia coli have recently emerged from the determination of the structure

  3. pH sensitivity of ammonium transport by Rhbg

    PubMed Central

    Abdulnour-Nakhoul, Solange M.; Schmidt, Eric; Doetjes, Rienk; Rabon, Edd; Hamm, L. Lee

    2010-01-01

    Rhbg is a membrane glycoprotein that is involved in NH3/NH4+ transport. Several models have been proposed to describe Rhbg, including an electroneutral NH4+/H+ exchanger, a uniporter, an NH4+ channel, or even a gas channel. In this study, we characterized the pH sensitivity of Rhbg expressed in Xenopus oocytes. We used two-electrode voltage clamp and ion-selective microelectrodes to measure NH4+-induced [and methyl ammonium (MA+)] currents and changes in intracellular pH (pHi), respectively. In oocytes expressing Rhbg, 5 mM NH4Cl (NH3/NH4+) at extracellular pH (pHo) of 7.5 induced an inward current, decreased pHi, and depolarized the cell. Raising pHo to 8.2 significantly enhanced the NH4+-induced current and pHi changes, whereas decreasing bath pH to 6.5 inhibited these changes. Lowering pHi (decreased by butyrate) also inhibited the NH4+-induced current and pHi decrease. In oocytes expressing Rhbg, 5 mM methyl amine hydrochloride (MA/MA+), often used as an NH4Cl substitute, induced an inward current, a pHi increase (not a decrease), and depolarization of the cell. Exposing the oocyte to MA/MA+ at alkaline bath pH (8.2) enhanced the MA+-induced current, whereas lowering bath pH to 6.5 inhibited the MA+ current completely. Exposing the oocyte to MA/MA+ at low pHi abolished the MA+-induced current and depolarization; however, pHi still increased. These data indicate that 1) transport of NH4+ and MA/MA+ by Rhbg is pH sensitive; 2) electrogenic NH4+ and MA+ transport are stimulated by alkaline pHo but inhibited by acidic pHi or pHo; and 3) electroneutral transport of MA by Rhbg is likely but is less sensitive to pH changes. PMID:20810915

  4. pH sensitivity of ammonium transport by Rhbg.

    PubMed

    Nakhoul, Nazih L; Abdulnour-Nakhoul, Solange M; Schmidt, Eric; Doetjes, Rienk; Rabon, Edd; Hamm, L Lee

    2010-12-01

    Rhbg is a membrane glycoprotein that is involved in NH(3)/NH(4)(+) transport. Several models have been proposed to describe Rhbg, including an electroneutral NH(4)(+)/H(+) exchanger, a uniporter, an NH(4)(+) channel, or even a gas channel. In this study, we characterized the pH sensitivity of Rhbg expressed in Xenopus oocytes. We used two-electrode voltage clamp and ion-selective microelectrodes to measure NH(4)(+)-induced [and methyl ammonium (MA(+))] currents and changes in intracellular pH (pH(i)), respectively. In oocytes expressing Rhbg, 5 mM NH(4)Cl (NH(3)/NH(4)(+)) at extracellular pH (pH(o)) of 7.5 induced an inward current, decreased pH(i), and depolarized the cell. Raising pH(o) to 8.2 significantly enhanced the NH(4)(+)-induced current and pH(i) changes, whereas decreasing bath pH to 6.5 inhibited these changes. Lowering pH(i) (decreased by butyrate) also inhibited the NH(4)(+)-induced current and pH(i) decrease. In oocytes expressing Rhbg, 5 mM methyl amine hydrochloride (MA/MA(+)), often used as an NH(4)Cl substitute, induced an inward current, a pH(i) increase (not a decrease), and depolarization of the cell. Exposing the oocyte to MA/MA(+) at alkaline bath pH (8.2) enhanced the MA(+)-induced current, whereas lowering bath pH to 6.5 inhibited the MA(+) current completely. Exposing the oocyte to MA/MA(+) at low pH(i) abolished the MA(+)-induced current and depolarization; however, pH(i) still increased. These data indicate that 1) transport of NH(4)(+) and MA/MA(+) by Rhbg is pH sensitive; 2) electrogenic NH(4)(+) and MA(+) transport are stimulated by alkaline pH(o) but inhibited by acidic pH(i) or pH(o); and 3) electroneutral transport of MA by Rhbg is likely but is less sensitive to pH changes.

  5. Stress corrosion cracking properties of 15-5PH steel

    NASA Technical Reports Server (NTRS)

    Rosa, Ferdinand

    1993-01-01

    Unexpected occurrence of failures, due to stress corrosion cracking (SCC) of structural components, indicate a need for improved characterization of materials and more advanced analytical procedures for reliably predicting structures performance. Accordingly, the purpose of this study was to determine the stress corrosion susceptibility of 15-5PH steel over a wide range of applied strain rates in a highly corrosive environment. The selected environment for this investigation was a highly acidified sodium chloride (NaCl) aqueous solution. The selected alloy for the study was a 15-5PH steel in the H900 condition. The slow strain rate technique was selected to test the metals specimens.

  6. EM-21 ALTERNATIVE ENHANCED CHEMICAL CLEANING PROGRAM FOR SLUDGE HEEL REMOVAL

    SciTech Connect

    Hay, M; King, W; Martino, C

    2009-12-18

    Preliminary studies in the EM-21 Alternative Chemical Cleaning Program have focused on understanding the dissolution of Hematite (a primary sludge heel phase) in oxalic acid, with a focus on minimizing oxalic acid usage. Literature reviews, thermodynamic modeling, and experimental results have all confirmed that pH control, preferably using a supplemental proton source, is critical to oxalate minimization. With pH control, iron concentrations as high as 0.103 M have been obtained in 0.11 M oxalic acid. This is consistent with the formation of a 1:1 (iron:oxalate) complex. The solubility of Hematite in oxalic acid has been confirmed to increase by a factor of 3 when the final solution pH decreases from 5 to below 1. This is consistent with literature predictions of a shift in speciation from a 1:3 to 1:1 as the pH is lowered. Above a solution pH of 6, little Hematite dissolves. These results emphasize the importance of pH control in optimizing Hematite dissolution in oxalic acid.

  7. Molecular Details of the PH Domain of ACAP1(BAR-PH) Protein Binding to PIP-Containing Membrane.

    PubMed

    Chan, Kevin Chun; Lu, Lanyuan; Sun, Fei; Fan, Jun

    2017-02-03

    ACAP1 proteins were previously reported to specifically bind PIP2-containing cell membranes and form well-structured protein lattices in order to conduct membrane tubulation. We carried out molecular dynamics simulations to characterize orientation of the PH domains with respect to the BAR domains inside the protein dimer. Followed by molecular dynamics simulations, we present a comprehensive orientation analysis of PH domain under different states including unbound and bound with lipids. We have examined two binding pockets on the PH domain and present PMF profiles of the two pockets to account for their preference to PIP2 lipids. Combining orientation analysis and studies of binding pockets, our simulations results reveal valuable molecular basis for protein-lipid interactions of ACAP1 proteins during membrane remodeling process.

  8. emPHasis-10: development of a health-related quality of life measure in pulmonary hypertension

    PubMed Central

    Yorke, Janelle; Corris, Paul; Gaine, Sean; Gibbs, J. Simon R.; Kiely, David G.; Harries, Carl; Pollock, Val; Armstrong, Iain

    2014-01-01

    The aim of this study was to develop a measure of the impact of pulmonary hypertension (PH) on health-related quality of life (HRQoL) as there is a need for a short, validated instrument that can be used in routine clinical practice. Interviews were conducted with 30 PH patients to derive 32 statements, which were presented as a semantic differential six-point scale (0–5), with contrasting adjectives at each end. This item list was completed by patients attending PH clinics across the UK and Ireland. Rasch analysis was applied to identify items fitting a uni-dimensional model. 226 patients (mean age 55.6±14 years; 70% female) with PH (82% had pulmonary arterial hypertension) completed the study questionnaires. 10 of the 32 items demonstrated fit to the Rasch model (Chi-squared 16; p>0.05) and generated the emPHasis-10 questionnaire. Test–retest (intraclass correlation coefficient 0.95, n=33) and internal consistency (Chronbach’s α=0.9) were strong. emPHasis-10 scores correlated consistently with other relevant measures and discriminated subgroups of patients stratified by World Health Organization functional class (ANOVA F=1.73; p<0.001). The emPHasis-10 is a short questionnaire for assessing HRQoL in pulmonary arterial hypertension. It has excellent measurement properties and is sensitive to differences in relevant clinical parameters. It is freely available for clinical and academic use. PMID:24232702

  9. Ligand accessibility and bioactivity of a hormone–dendrimer conjugate depend on pH and pH history

    DOE PAGES

    Kim, Sung Hoon; Madak-Erdogan, Zeynep; Bae, Sung Chul; ...

    2015-07-17

    Estrogen conjugates with a polyamidoamine (PAMAM) dendrimer have shown remarkably selective regulation of the nongenomic actions of estrogens in target cells in this paper. In response to pH changes, however, these estrogen–dendrimer conjugates (EDCs) display a major morphological transition that alters the accessibility of the estrogen ligands that compromises the bioactivity of the EDC. A sharp break in dynamic behavior near pH 7 occurs for three different ligands on the surface of a PAMAM-G6 dendrimer: a fluorophore (tetramethylrhodamine [TMR]) and two estrogens (17α-ethynylestradiol and diphenolic acid). Collisional quenching and time-resolved fluorescence anisotropy experiments with TMR–PAMAM revealed high ligand shielding abovemore » pH 7 and low shielding below pH 7. Furthermore, when the pH was cycled from 8.5 (conditions of ligand–PAMAM conjugation) to 4.5 (e.g., endosome/lysosome) and through 6.5 (e.g., hypoxic environment) back to pH 8.5, the 17α-ethynylestradiol– and diphenolic acid–PAMAM conjugates experienced a dramatic, irreversible loss in cell stimulatory activity; dynamic NMR studies indicated that the hormonal ligands had become occluded within the more hydrophobic core of the PAMAM dendrimer. Thus, the active state of these estrogen–dendrimer conjugates appears to be metastable. Finally, this pH-dependent irreversible masking of activity is of considerable relevance to the design of drug conjugates with amine-bearing PAMAM dendrimers.« less

  10. Meet EPA Ecologist Michael Murrell, Ph.D.

    EPA Pesticide Factsheets

    Michael Murrel, Ph.D., is a EPA research ecologist working on the Gulf of Mexico Hypoxia Project, helping develop models of the northern Gulf to quantify the links between freshwater flowing into the Gulf from the land, nutrients, and hypoxia—“dead zones”

  11. Promoting Creativity in PhD Supervision: Tensions and Dilemmas

    ERIC Educational Resources Information Center

    Whitelock, Denise; Faulkner, Dorothy; Miell, Dorothy

    2008-01-01

    In this paper we argue that the processes of collaborative creativity are just as important within the sociocultural context of PhD supervisory practice, as they are in other organizational and educational settings. In order to test this claim a series of interviews with supervisors and students were undertaken to uncover the pedagogic processes…

  12. Vance Berger, PhD | Division of Cancer Prevention

    Cancer.gov

    Dr. Vance Berger completed his PhD in statistics at Rutgers University in 1995, and then began working at the FDA. This is where he developed his research focus on biases and threats to the validity of medical studies, especially clinical trials. In 1999, Dr. Berger joined the NCI, and has remained ever since. |

  13. Measures for Ph.D. Evaluation: The Recruitment Process

    ERIC Educational Resources Information Center

    D'Agostino, Antonella; Fruzzetti, Stefania; Ghellini, Giulio; Neri, Laura

    2011-01-01

    In the last years the quality of Higher Education (HE) system and its evaluation have been key issues of the political and scientific debate on education policies all over Europe. In the wide landscape that involves the entire HE system we draw attention on the third level of its organization, i.e. the Ph.D. In particular, this paper discusses the…

  14. The PhD Project: How Successful Is It?

    ERIC Educational Resources Information Center

    Schwartz, Bill N.; Williams, Satina V.; Walden, W. Darrell

    2011-01-01

    The PhD Project's mission to diversify the work force by increasing the diversity of business school faculty is quite admirable, but is the Project successful? To gather insights toward responding to that question and to offer suggestions, we reviewed three of the Project's objectives that relate most closely to minority doctoral students and…

  15. Annotation of Fusarium graminearum (PH-1) Version 5.0

    PubMed Central

    Hammond-Kosack, Kim E.

    2017-01-01

    ABSTRACT Fusarium graminearum floral infections are a major risk to the global supply of safe cereal grains. We report updates to the PH-1 reference genome and significant improvements to the annotation. Changes include introduction of legacy annotation identifiers, new gene models, secretome and effectorP predictions, and inclusion of extensive untranslated region (UTR) annotations. PMID:28082505

  16. Carbon Nanotube Chemiresistor for Wireless pH Sensing

    NASA Astrophysics Data System (ADS)

    Gou, Pingping; Kraut, Nadine D.; Feigel, Ian M.; Bai, Hao; Morgan, Gregory J.; Chen, Yanan; Tang, Yifan; Bocan, Kara; Stachel, Joshua; Berger, Lee; Mickle, Marlin; Sejdić, Ervin; Star, Alexander

    2014-03-01

    The ability to accurately measure real-time pH fluctuations in-vivo could be highly advantageous. Early detection and potential prevention of bacteria colonization of surgical implants can be accomplished by monitoring associated acidosis. However, conventional glass membrane or ion-selective field-effect transistor (ISFET) pH sensing technologies both require a reference electrode which may suffer from leakage of electrolytes and potential contamination. Herein, we describe a solid-state sensor based on oxidized single-walled carbon nanotubes (ox-SWNTs) functionalized with the conductive polymer poly(1-aminoanthracene) (PAA). This device had a Nernstian response over a wide pH range (2-12) and retained sensitivity over 120 days. The sensor was also attached to a passively-powered radio-frequency identification (RFID) tag which transmits pH data through simulated skin. This battery-less, reference electrode free, wirelessly transmitting sensor platform shows potential for biomedical applications as an implantable sensor, adjacent to surgical implants detecting for infection.

  17. Structure of human saposin A at lysosomal pH.

    PubMed

    Hill, Chris H; Read, Randy J; Deane, Janet E

    2015-07-01

    The saposins are essential cofactors for the normal lysosomal degradation of complex glycosphingolipids by acid hydrolase enzymes; defects in either saposin or hydrolase function lead to severe metabolic diseases. Saposin A (SapA) activates the enzyme β-galactocerebrosidase (GALC), which catalyzes the breakdown of β-D-galactocerebroside, the principal lipid component of myelin. SapA is known to bind lipids and detergents in a pH-dependent manner; this is accompanied by a striking transition from a `closed' to an `open' conformation. However, previous structures were determined at non-lysosomal pH. This work describes a 1.8 Å resolution X-ray crystal structure determined at the physiologically relevant lysosomal pH 4.8. In the absence of lipid or detergent at pH 4.8, SapA is observeed to adopt a conformation closely resembling the previously determined `closed' conformation, showing that pH alone is not sufficient for the transition to the `open' conformation. Structural alignments reveal small conformational changes, highlighting regions of flexibility.

  18. Online Ph.D. Program Delivery Models and Student Success

    ERIC Educational Resources Information Center

    Jorissen, Shari L.; Keen, James P.; Riedel, Eric S.

    2015-01-01

    The purpose of this study was to provide information to an online university that offers Ph.D. programs in three formats: knowledge area modules (or KAM, a type of faculty-led, self-directed doctoral study), course-based model, and mixed model (a combination of the KAM and course-based models). The investigators sought to determine why students…

  19. Gender Differences in Research Patterns among PhD Economists

    ERIC Educational Resources Information Center

    Barbezat, Debra A.

    2006-01-01

    This study is based on a 1996 survey of PhD economists working in the academic and nonacademic sectors since 1989. Despite a raw gender difference in all types of research output, the male dummy variable proves statistically significant in predicting only one publication measure. In a full sample and faculty subsample, number of years since…

  20. Earth and Space Science PhDs: Class of 2000

    NASA Astrophysics Data System (ADS)

    Giesler, J.

    2001-12-01

    The American Geophysical Union (AGU) and the American Geological Institute (AGI) have been collecting data on recent PhDs in the geosciences for 5 years (1996-2000). Over these years continual improvement has been recorded in the job market through indicators such as time to find employment and starting salaries. As these indicators continue to improve, so too does the perception of the job market in general. There are several characteristics that are unique to PhDs in the geosciences. Unlike physical science graduates, there is a significant number who have been working full-time at least one year prior to earning their PhD. Recent graduates employed prior to graduation are heavily concentrated in Solid Earth Geology (41%) followed by Atmospheric Sciences (19%) and Oceanography (12%). A second distinguishable feature of Earth & space science PhDs is their age. Each year there is a higher percentage of recent graduates over the age of 40: 16% in 1998, 20% in 1999, and 23% in 2000. In 2000, the average time between earning a B.S. and starting a graduate program was 4.6 years. Both 1999 and 2000 show a drop in the overall numbers of postdoctoral appointments. This suggests that greater than 50% of the recent graduates are finding full-time permanent employment. Of the geoscience subfields, oceanography has greatest number of people obtaining employment outside the field.

  1. The Production Rate and Employment of Ph.D. Astronomers

    NASA Astrophysics Data System (ADS)

    Metcalfe, Travis S.

    2007-05-01

    As in many sciences, the production rate of new Ph.D. astronomers is decoupled from the global demand for trained scientists. As noted by Thronson (1991, PASP, 103, 90), overproduction appears to be built into the system, making the mathematical formulation of surplus astronomer production similar to that for industrial pollution models -- an unintended side effect of the process. Following Harris (1994, ASP Conf., 57, 12), I document the production of Ph.D. astronomers from 1990 to 2005 using the online Dissertation Abstracts database. To monitor the changing patterns of employment, I examine the number of postdoctoral, tenure-track, and other jobs advertised in the AAS Job Register during this same period. Although the current situation is clearly unsustainable, it was much worse a decade ago with nearly 7 new Ph.D. astronomers in 1995 for every new tenure-track job. While the number of new permanent positions steadily increased throughout the late 1990's, the number of new Ph.D. recipients gradually declined. After the turn of the century, the production of new astronomers leveled off, but new postdoctoral positions grew dramatically. There has also been recent growth in the number of non-tenure-track lecturer, research, and support positions. This is just one example of a larger cultural shift to temporary employment that is happening throughout society -- it is not unique to astronomy.

  2. Engineering a pH responsive pore forming protein.

    PubMed

    Kisovec, Matic; Rezelj, Saša; Knap, Primož; Cajnko, Miša Mojca; Caserman, Simon; Flašker, Ajda; Žnidaršič, Nada; Repič, Matej; Mavri, Janez; Ruan, Yi; Scheuring, Simon; Podobnik, Marjetka; Anderluh, Gregor

    2017-02-08

    Listeriolysin O (LLO) is a cytolysin capable of forming pores in cholesterol-rich lipid membranes of host cells. It is conveniently suited for engineering a pH-governed responsiveness, due to a pH sensor identified in its structure that was shown before to affect its stability. Here we introduced a new level of control of its hemolytic activity by making a variant with hemolytic activity that was pH-dependent. Based on detailed structural analysis coupled with molecular dynamics and mutational analysis, we found that the bulky side chain of Tyr406 allosterically affects the pH sensor. Molecular dynamics simulation further suggested which other amino acid residues may also allosterically influence the pH-sensor. LLO was engineered to the point where it can, in a pH-regulated manner, perforate artificial and cellular membranes. The single mutant Tyr406Ala bound to membranes and oligomerized similarly to the wild-type LLO, however, the final membrane insertion step was pH-affected by the introduced mutation. We show that the mutant toxin can be activated at the surface of artificial membranes or living cells by a single wash with slightly acidic pH buffer. Y406A mutant has a high potential in development of novel nanobiotechnological applications such as controlled release of substances or as a sensor of environmental pH.

  3. [Regulation effects of tourmaline on seawater pH value].

    PubMed

    Xia, Meisheng; Zhang, Hongmei; Hu, Caihong; Xu, Zirong

    2005-10-01

    In this paper, chemical analysis, X-ray diffraction and atomic force microscopy were employed to examine the characteristics of tourmaline produced in east Inner Mongolia Autonomous Region, and batch experiments were conducted to study its regulation effects on seawater pH value. The factors affecting the regulation, such as the dosage of tourmaline and the salinity and initial pH value of seawater, were also studied. The results showed that tourmaline could regulate the seawater pH value from its initial 3 and 10 to 7.1 and 8.9, respectively, and the regulation effect was greater in the seawater with lower salinity, e.g., after 120 minutes treatment, the initial pH value (5.0) of the seawater with a salinity of 5, 10, 15, 20 and 35 was increased by 3.24, 3.16, 3.06, 2.99 and 2.85 unit, respectively. Tourmaline had little effect on seawater conductivity. This study would provide an experimental base for the application of tourmaline in aquaculture.

  4. DISSOLVED ORGANIC MATTER AND METALS: EFFECTS OF PH ON PARTITIONING

    EPA Science Inventory

    Eighteen Dutch soils were extracted in aqueous solutions at varying pH. Extracts were analyzed for Cd, Cu, Ni, Pb, and Zn by ICP-AES. Extract dissolved organic carbon (DOC) was fractionated into three operationally defined fractions: hydrophilic acids (Hyd), fulvic acids (FA), an...

  5. Biochemical Stabilization of Glucagon at Alkaline pH

    PubMed Central

    Jackson, Melanie A.; Castle, Jessica R.; El Youssef, Joseph; Bakhtiani, Parkash A.; Bergstrom, Colin P.; Carroll, Julie M.; Breen, Matthew E.; Leonard, Gerald L.; David, Larry L.; Roberts, Charles T.; Ward, W. Kenneth

    2014-01-01

    Abstract Background: For patients with type 1 diabetes mellitus, a bihormonal artificial endocrine pancreas system utilizing glucagon and insulin has been found to stabilize glycemic control. However, commercially available formulations of glucagon cannot currently be used in such systems because of physical instability characterized by aggregation and chemical degradation. Storing glucagon at pH 10 blocks protein aggregation but results in chemical degradation. Reductions in pH minimize chemical degradation, but even small reductions increase protein aggregation. We hypothesized that common pharmaceutical excipients accompanied by a new excipient would inhibit glucagon aggregation at an alkaline pH. Methods and Results: As measured by tryptophan intrinsic fluorescence shift and optical density at 630 nm, protein aggregation was indeed minimized when glucagon was formulated with curcumin and albumin. This formulation also reduced chemical degradation, measured by liquid chromatography with mass spectrometry. Biological activity was retained after aging for 7 days in an in vitro cell-based bioassay and also in Yorkshire swine. Conclusions: Based on these findings, a formulation of glucagon stabilized with curcumin, polysorbate-80, l-methionine, and albumin at alkaline pH in glycine buffer may be suitable for extended use in a portable pump in the setting of a bihormonal artificial endocrine pancreas. PMID:24968220

  6. Miniaturized metal oxide pH sensors for bacteria detection.

    PubMed

    Uria, Naroa; Abramova, Natalia; Bratov, Andrey; Muñoz-Pascual, Francesc-Xavier; Baldrich, Eva

    2016-01-15

    It is well known that the metabolic activity of some microorganisms results in changes of pH of the culture medium, a phenomenon that can be used for detection and quantification of bacteria. However, conventional glass electrodes that are commonly used for pH measurements are bulky, fragile and expensive, which hinders their application in miniaturized systems and encouraged to the search for alternatives. In this work, two types of metal oxide pH sensors have been tested to detect the metabolic activity of the bacterium Escherichia coli (E. coli). These pH sensors were produced on silicon chips with platinum metal contacts, onto which thin layers of IrOx or Ta2O5 were incorporated by two different methods (electrodeposition and e-beam sputtering, respectively). In order to facilitate measurement in small sample volumes, an Ag/AgCl pseudo-reference was also screen-printed in the chip and was assayed in parallel to an external Ag/AgCl reference electrode. As it is shown, the developed sensors generated results indistinguishable from those provided by a conventional glass pH-electrode but could be operated in significantly smaller sample volumes. After optimization of the detection conditions, the metal oxide sensors are successfully applied for detection of increasing concentrations of viable E. coli, with detection of less than 10(3)cfu mL(-1) in undiluted culture medium in just 5h.

  7. PhDs by Publications: An "Easy Way Out"?

    ERIC Educational Resources Information Center

    Niven, Penelope; Grant, Carolyn

    2012-01-01

    PhDs by publications are a relatively new model for doctoral research, especially in the context of the Humanities or Education. This paper describes two writers' experiences of conducting doctoral studies in this genre and in these faculties. Each discover alternative ways of employing a body of published research papers in development of an…

  8. Karl Krueger, PhD | Division of Cancer Prevention

    Cancer.gov

    Dr. Karl Krueger received a PhD in biochemistry from Vanderbilt University and continued his research training at NIH as a postdoctoral fellow before joining the faculty at Georgetown University School of Medicine. His research throughout this period focused on different aspects of drug receptors and their role in the nervous system. |

  9. Vaginal pH: Home-Use Tests

    MedlinePlus

    ... the pH paper to the color on the chart provided with the test kit. The number on the chart for the color that best matches the color ... Medical Devices Radiation-Emitting Products Vaccines, Blood & Biologics Animal & Veterinary Cosmetics Tobacco Products

  10. Modulation of autophagic activity by extracellular pH.

    PubMed

    Xu, Teng; Su, Hang; Ganapathy, Suthakar; Yuan, Zhi-Min

    2011-11-01

    Reprogramming energy metabolism from oxidative phosphorylation to aerobic glycolysis, a common feature of human cancer, is associated with a relative acidic tumor microenvironment which can sometimes be further accentuated by hypoxia operating within most solid tumors. We found that alteration of extracellular pH induces marked and rapid changes of autophagic activity. Interestingly, acidic and basic conditions induced completely opposite effect on autophagy, with its activity suppressed at lower pH whereas stimulated at higher pH. Gene knockdown experiments indicated that pH induced-autophagy requires Beclin 1, Vps34 and Atg5, key components of the autophagy pathway. Of note, an acidic condition not only inhibits the basal but also blocks the starvation-induced autophagy activity. Significantly, examination of different areas of tumor mass revealed a lower autophagic activity within the inner region than the outer region. These findings have important implications on the connections between autophagy and cancer as well as a wide range of other physiological and pathological processes.

  11. Catalytic gold nanoparticle driven pH specific chemical locomotion.

    PubMed

    Dey, Krishna Kanti; Panda, Biswa Ranjan; Paul, Anumita; Basu, Saurabh; Chattopadhyay, Arun

    2010-08-15

    Gold nanoparticle (Au NP) catalyzed decomposition of alkaline hydrogen peroxide has been utilized in driving chemical locomotives in a liquid. Au NPs deposited on spherical micron sized polymer resin beads catalyzed the decomposition of H(2)O(2) in the pH range 9.1-10.8. The O(2) gas bubbles produced in the decomposition moved the beads upward with average velocities that depended on the pH of the solution. The measured average velocity of the bead increased with the increase in pH in the range 9.1-10.8. Above this pH, the self-decomposition of H(2)O(2) produced sufficient bubbles in the medium that made the motion haphazard and thus prevented a clear measurement of the velocity. The observed accelerated motion of the locomotive has been explained by considering the time-dependent growth of O(2) gas bubbles on the polymer, while taking into consideration desorption and other factors.

  12. Richard Mazurchuk, PhD | Division of Cancer Prevention

    Cancer.gov

    Dr. Richard Mazurchuk received a BS in Physics and MS and PhD in Biophysics from SUNY Buffalo. His research focused on developing novel multi-modality imaging techniques, contrast (enhancing) agents and methods to assess the efficacy of experimental therapeutics. |

  13. An Analysis of Ph.D. Examiners' Reports in Engineering

    ERIC Educational Resources Information Center

    Prieto, Elena; Holbrook, Allyson; Bourke, Sid

    2016-01-01

    In recent years, there have been increasing calls for an overall transformation of the nature of engineering Ph.D. programs and the way theses are assessed. There exists a need to understand the examination process to ensure the best quality outcome for candidates in engineering. The work we present in this paper uses data collected between 2003…

  14. Engineering a pH responsive pore forming protein

    PubMed Central

    Kisovec, Matic; Rezelj, Saša; Knap, Primož; Cajnko, Miša Mojca; Caserman, Simon; Flašker, Ajda; Žnidaršič, Nada; Repič, Matej; Mavri, Janez; Ruan, Yi; Scheuring, Simon; Podobnik, Marjetka; Anderluh, Gregor

    2017-01-01

    Listeriolysin O (LLO) is a cytolysin capable of forming pores in cholesterol-rich lipid membranes of host cells. It is conveniently suited for engineering a pH-governed responsiveness, due to a pH sensor identified in its structure that was shown before to affect its stability. Here we introduced a new level of control of its hemolytic activity by making a variant with hemolytic activity that was pH-dependent. Based on detailed structural analysis coupled with molecular dynamics and mutational analysis, we found that the bulky side chain of Tyr406 allosterically affects the pH sensor. Molecular dynamics simulation further suggested which other amino acid residues may also allosterically influence the pH-sensor. LLO was engineered to the point where it can, in a pH-regulated manner, perforate artificial and cellular membranes. The single mutant Tyr406Ala bound to membranes and oligomerized similarly to the wild-type LLO, however, the final membrane insertion step was pH-affected by the introduced mutation. We show that the mutant toxin can be activated at the surface of artificial membranes or living cells by a single wash with slightly acidic pH buffer. Y406A mutant has a high potential in development of novel nanobiotechnological applications such as controlled release of substances or as a sensor of environmental pH. PMID:28176876

  15. Christos Patriotis, PhD | Division of Cancer Prevention

    Cancer.gov

    Dr. Christos Patriotis obtained his MSc in Biochemistry from the University of Sofia, Bulgaria in 1985 and his PhD in Molecular Biology from the Bulgarian Academy of Sciences in 1990. Postdoctoral training focused on signal transduction and tumor cell biology. |

  16. Robert Shoemaker, PhD | Division of Cancer Prevention

    Cancer.gov

    Dr. Robert Shoemaker obtained his PhD in human genetics from the Graduate School of Public Health of the University of Pittsburgh in 1975. Following postdoctoral experience at the Armed Forces Institute of Pathology he moved to the Children's Hospital Medical Center of Akron. His research on pediatric tumors led to an interest in the genetics of drug resistance and new drug discovery. |

  17. Asad Umar, DVM, PhD | Division of Cancer Prevention

    Cancer.gov

    Dr. Asad Umar received his PhD in Biochemistry and Immunology at the Johns Hopkins University in Baltimore, MD, in 1993. He conducted his postdoctoral training in the laboratories of Patricia Gearhart in Baltimore, MD and Thomas Kunkel at the National Institutes of Environmental Health Sciences in Research Triangle Park, NC. Dr. |

  18. Engineering a pH responsive pore forming protein

    NASA Astrophysics Data System (ADS)

    Kisovec, Matic; Rezelj, Saša; Knap, Primož; Cajnko, Miša Mojca; Caserman, Simon; Flašker, Ajda; Žnidaršič, Nada; Repič, Matej; Mavri, Janez; Ruan, Yi; Scheuring, Simon; Podobnik, Marjetka; Anderluh, Gregor

    2017-02-01

    Listeriolysin O (LLO) is a cytolysin capable of forming pores in cholesterol-rich lipid membranes of host cells. It is conveniently suited for engineering a pH-governed responsiveness, due to a pH sensor identified in its structure that was shown before to affect its stability. Here we introduced a new level of control of its hemolytic activity by making a variant with hemolytic activity that was pH-dependent. Based on detailed structural analysis coupled with molecular dynamics and mutational analysis, we found that the bulky side chain of Tyr406 allosterically affects the pH sensor. Molecular dynamics simulation further suggested which other amino acid residues may also allosterically influence the pH-sensor. LLO was engineered to the point where it can, in a pH-regulated manner, perforate artificial and cellular membranes. The single mutant Tyr406Ala bound to membranes and oligomerized similarly to the wild-type LLO, however, the final membrane insertion step was pH-affected by the introduced mutation. We show that the mutant toxin can be activated at the surface of artificial membranes or living cells by a single wash with slightly acidic pH buffer. Y406A mutant has a high potential in development of novel nanobiotechnological applications such as controlled release of substances or as a sensor of environmental pH.

  19. pH Effects on Electrospray Ionization Efficiency

    NASA Astrophysics Data System (ADS)

    Liigand, Jaanus; Laaniste, Asko; Kruve, Anneli

    2016-12-01

    Electrospray ionization efficiency is known to be affected by mobile phase composition. In this paper, a detailed study of analyte ionization efficiency dependence on mobile phase pH is presented. The pH effect was studied on 28 compounds with different chemical properties. Neither pK a nor solution phase ionization degree by itself was observed to be sufficient at describing how aqueous phase pH affects the ionization efficiency of the analyte. Therefore, the analyte behavior was related to various physicochemical properties via linear discriminant analyses. Distinction between pH-dependent and pH-independent compounds was achieved using two parameters: number of potential charge centers and hydrogen bonding acceptor capacity (in the case of 80% acetonitrile) or polarity of neutral form of analyte and pK a (in the case of 20% acetonitrile). It was also observed that decreasing pH may increase ionization efficiency of a compound by more than two orders of magnitude.

  20. Peer Mentorship and Transformational Learning: PhD Student Experiences

    ERIC Educational Resources Information Center

    Preston, Jane P.; Ogenchuk, Marcella J.; Nsiah, Joseph K.

    2014-01-01

    The purpose of the paper is to describe our peer mentorship experiences and explain how these experiences fostered transformational learning during our PhD graduate program in educational administration. As a literature backdrop, we discuss characteristics of traditional forms of mentorship and depict how our experiences of peer mentorship was…

  1. Supervising the PhD: A Guide to Success.

    ERIC Educational Resources Information Center

    Delamont, Sara; Atkinson, Paul; Parry, Odette

    This handbook is a practical guide for the novice and experienced supervisor of Ph.D. students focusing on the British system. The book is organized to follow the progress of a student from starting out to a career after the viva voce examination. The chapters are: (1) "A Most Persuasive Piece of Argument"; (2) "Caught and Held by a…

  2. Improved pH buffering agent for sodium hypochlorite

    NASA Technical Reports Server (NTRS)

    Nash, J. R.; Veeder, L. N.

    1969-01-01

    Sodium citrate/citric acid was found to be an effective buffer for pH control when used with sodium hypochlorite. The mixture does not corrode aluminum. The buffer appears to form a type of conversion coating that may provide corrosion-resistant properties to aluminum in other applications.

  3. Crystallogenesis of bacteriophage P22 tail accessory factor gp26 at acidic and neutral pH

    SciTech Connect

    Cingolani, Gino Andrews, Dewan; Casjens, Sherwood

    2006-05-01

    The crystallogenesis of bacteriophage P22 tail-fiber gp26 is described. To study possible pH-induced conformational changes in gp26 structure, native trimeric gp26 has been crystallized at acidic pH (4.6) and a chimera of gp26 fused to maltose-binding protein (MBP-gp26) has been crystallized at neutral and alkaline pH (7-10). Gp26 is one of three phage P22-encoded tail accessory factors essential for stabilization of viral DNA within the mature capsid. In solution, gp26 exists as an extended triple-stranded coiled-coil protein which shares profound structural similarities with class I viral membrane-fusion protein. In the cryo-EM reconstruction of P22 tail extracted from mature virions, gp26 forms an ∼220 Å extended needle structure emanating from the neck of the tail, which is likely to be brought into contact with the cell’s outer membrane when the viral DNA-injection process is initiated. To shed light on the potential role of gp26 in cell-wall penetration and DNA injection, gp26 has been crystallized at acidic, neutral and alkaline pH. Crystals of native gp26 grown at pH 4.6 diffract X-rays to 2.0 Å resolution and belong to space group P2{sub 1}, with a dimer of trimeric gp26 molecules in the asymmetric unit. To study potential pH-induced conformational changes in the gp26 structure, a chimera of gp26 fused to maltose-binding protein (MBP-gp26) was generated. Hexagonal crystals of MBP-gp26 were obtained at neutral and alkaline pH using the high-throughput crystallization robot at the Hauptman–Woodward Medical Research Institute, Buffalo, NY, USA. These crystals diffract X-rays to beyond 2.0 Å resolution. Structural analysis of gp26 crystallized at acidic, neutral and alkaline pH is in progress.

  4. Structural basis of dual Ca(2+)/pH regulation of the endolysosomal TRPML1 channel.

    PubMed

    Li, Minghui; Zhang, Wei K; Benvin, Nicole M; Zhou, Xiaoyuan; Su, Deyuan; Li, Huan; Wang, Shu; Michailidis, Ioannis E; Tong, Liang; Li, Xueming; Yang, Jian

    2017-01-23

    The activities of organellar ion channels are often regulated by Ca(2+) and H(+), which are present in high concentrations in many organelles. Here we report a structural element critical for dual Ca(2+)/pH regulation of TRPML1, a Ca(2+)-release channel crucial for endolysosomal function. TRPML1 mutations cause mucolipidosis type IV (MLIV), a severe lysosomal storage disorder characterized by neurodegeneration, mental retardation and blindness. We obtained crystal structures of the 213-residue luminal domain of human TRPML1 containing three missense MLIV-causing mutations. This domain forms a tetramer with a highly electronegative central pore formed by a novel luminal pore loop. Cysteine cross-linking and cryo-EM analyses confirmed that this architecture occurs in the full-length channel. Structure-function studies demonstrated that Ca(2+) and H(+) interact with the luminal pore and exert physiologically important regulation. The MLIV-causing mutations disrupt the luminal-domain structure and cause TRPML1 mislocalization. Our study reveals the structural underpinnings of TRPML1's regulation, assembly and pathogenesis.

  5. Effects of pH on aquatic biodegradation processes

    NASA Astrophysics Data System (ADS)

    Krachler, R. F.; Krachler, R.; Stojanovic, A.; Wielander, B.; Herzig, A.

    2009-01-01

    To date, little is known about the pH-stimulated mineralization of organic matter in aquatic environments. In this study, we investigated biodegradation processes in alkaline waters. Study site is a large shallow soda lake in Central Europe (Neusiedler See/Ferto). The decomposition rate of plant litter was measured as a function of pH by incubating air-saturated lake-water samples in contact with Phragmites litter (leaves) from the littoral vegetation. All samples showed high decomposition rates (up to 32% mass loss within 35 days) and a characteristic two-step degradation mechanism. During the degradation process, the solid plant litter was dissolved forming humic colloids. Subsequently, the humic colloids were mineralized to CO2 in the water column. The decomposition rate was linearly related to pH. Increasing pH values accelerated significantly the leaching of humic colloids as well as the final degradation process. The observed two-step mechanism controls the wetland/lake/air carbon fluxes, since large quantities of humic colloids are currently produced in the reed belt, exported through wind-driven circulations and incorporated into the open lake foodweb. At present, the lake is rapidly shrinking due to peat deposition in the littoral zone, whereas it has been resistant to silting-up processes for thousands of years. In order to investigate the cause of this abrupt change, the chemical composition of the lake-water was measured during 1995-2007. A thorough analysis of these data revealed that major lake-water discharges through the lake's artificial outlet channel led to a decline in salinity and alkalinity. According to our estimates, the lake's original salinity and alkalinity was 70-90% higher compared to the present conditions, with the consequence of substantially lower pH values in the present lake. The observed pH dependence of reed litter biodegradation rates points to a causal connection between low pH values and accumulation of peat in the lake basin

  6. Nitric oxide and pH modulation in gynaecological cancer.

    PubMed

    Sanhueza, Carlos; Araos, Joaquín; Naranjo, Luciano; Barros, Eric; Subiabre, Mario; Toledo, Fernando; Gutiérrez, Jaime; Chiarello, Delia I; Pardo, Fabián; Leiva, Andrea; Sobrevia, Luis

    2016-12-01

    Nitric oxide plays several roles in cellular physiology, including control of the vascular tone and defence against pathogen infection. Neuronal, inducible and endothelial nitric oxide synthase (NOS) isoforms synthesize nitric oxide. Cells generate acid and base equivalents, whose physiological intracellular concentrations are kept due to membrane transport systems, including Na(+) /H(+) exchangers and Na(+) /HCO3(-) transporters, thus maintaining a physiological pH at the intracellular (~7.0) and extracellular (~7.4) medium. In several pathologies, including cancer, cells are exposed to an extracellular acidic microenvironment, and the role for these membrane transport mechanisms in this phenomenon is likely. As altered NOS expression and activity is seen in cancer cells and because this gas promotes a glycolytic phenotype leading to extracellular acidosis in gynaecological cancer cells, a pro-inflammatory microenvironment increasing inducible NOS expression in this cell type is feasible. However, whether abnormal control of intracellular and extracellular pH by cancer cells regards with their ability to synthesize or respond to nitric oxide is unknown. We, here, discuss a potential link between pH alterations, pH controlling membrane transport systems and NOS function. We propose a potential association between inducible NOS induction and Na(+) /H(+) exchanger expression and activity in human ovary cancer. A potentiation between nitric oxide generation and the maintenance of a low extracellular pH (i.e. acidic) is proposed to establish a sequence of events in ovarian cancer cells, thus preserving a pro-proliferative acidic tumour extracellular microenvironment. We suggest that pharmacological therapeutic targeting of Na(+) /H(+) exchangers and inducible NOS may have benefits in human epithelial ovarian cancer.

  7. Regulation of Vacuolar pH in Citrus limon

    SciTech Connect

    Lincoln Taiz

    2005-06-22

    The primary objective of this grant was to characterize the vacuolar V-ATPase of lemon fruits. Lemon fruit vacuoles have an internal pH of about 2.5. Since a typical plant vacuole has a luminal pH of around 5.5, the lemon fruit V-APTase must have special properties which allow it to acidify the lumen to such a low pH: (1) it might have a different structure; (2) it might have a different H{sup +}/ATP stoichiometry; and (3) it might be regulated differently. During the course of the investigations (which began in 1996) they characterized these aspects of the V-ATPases of both lemon fruits and lime fruits. They examined lime fruits because of the availability of both acidic limes with a low vacuolar pH and sweet limes, which have a much higher vacuolar pH. The existence of two types of lime fruits allowed a comparison of the V-ATPases of the two varieties. In this report they are including two publications from 1996 and 1997 as background for the later publications. A review article with Heven Sze on V-ATPase nomenclature was also generated during the funding period. In addition to the studies on citrus fruit vacuoles, they also initiated studies in two new areas: polar auxin transport and the regulation of stomatal opening by UV-B irradiation. These studies were intended to serve as a basis of future separate grants, but the proposals they submitted on these topics were not funded.

  8. Rural Emergency Medical Services (EMS) and Trauma

    MedlinePlus

    ... a rural EMS unit find funding for major equipment, such as an ambulance? The following programs can ... EMS units. Grants may be used to purchase equipment (including vehicles), provide training, establish wellness and fitness ...

  9. The PhEDEx next-gen website

    NASA Astrophysics Data System (ADS)

    Egeland, R.; Huang, C.-H.; Rossman, P.; Sundarrajan, P.; Wildish, T.

    2012-12-01

    PhEDEx is the data-transfer management solution written by CMS. It consists of agents running at each site, a website for presentation of information, and a web-based data-service for scripted access to information. The website allows users to monitor the progress of data-transfers, the status of site agents and links between sites, and the overall status and behaviour of everything about PhEDEx. It also allows users to make and approve requests for data-transfers and for deletion of data. It is the main point-of-entry for all users wishing to interact with PhEDEx. For several years, the website has consisted of a single perl program with about 10K SLOC. This program has limited capabilities for exploring the data, with only coarse filtering capabilities and no context-sensitive awareness. Graphical information is presented as static images, generated on the server, with no interactivity. It is also not well connected to the rest of the PhEDEx codebase, since much of it was written before the data-service was developed. All this makes it hard to maintain and extend. We are re-implementing the website to address these issues. The UI is being rewritten in Javascript, replacing most of the server-side code. We are using the YUI toolkit to provide advanced features and context-sensitive interaction, and will adopt a Javascript charting library for generating graphical representations client-side. This relieves the server of much of its load, and automatically improves server-side security. The Javascript components can be re-used in many ways, allowing custom pages to be developed for specific uses. In particular, standalone test-cases using small numbers of components make it easier to debug the Javascript than it is to debug a large server program. Information about PhEDEx is accessed through the PhEDEx data-service, since direct SQL is not available from the clients’ browser. This provides consistent semantics with other, externally written monitoring tools, which

  10. The European Mobile System (EMS)

    NASA Technical Reports Server (NTRS)

    Jongejans, A.; Rogard, R.; Mistretta, I.; Ananasso, F.

    1993-01-01

    The European Space Agency is presently procuring an L band payload in order to promote a regional European L band system coping with the specific needs of the European market. The payload, and the two communications systems to be supported, are described below. The potential market for EMS in Europe is discussed.

  11. Carbon Dioxide Addition to Microbial Fuel Cell Cathodes Maintains Sustainable Catholyte pH and Improves Anolyte pH, Alkalinity, and Conductivity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bioelectrochemical system (BES) pH imbalances develop due to anodic proton-generating oxidation reactions and cathodic hydroxide-ion-generating reduction reactions. Until now, workers added unsustainable buffers to reduce the pH difference between the anode and cathode because the pH imbalance cont...

  12. 21 CFR 868.1170 - Indwelling blood hydrogen ion concentration (pH) analyzer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Indwelling blood hydrogen ion concentration (pH... Indwelling blood hydrogen ion concentration (pH) analyzer. (a) Identification. An indwelling blood hydrogen ion concentration (pH) analyzer is a device that consists of a catheter-tip pH electrode and that...

  13. 21 CFR 868.1170 - Indwelling blood hydrogen ion concentration (pH) analyzer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Indwelling blood hydrogen ion concentration (pH... Indwelling blood hydrogen ion concentration (pH) analyzer. (a) Identification. An indwelling blood hydrogen ion concentration (pH) analyzer is a device that consists of a catheter-tip pH electrode and that...

  14. 21 CFR 868.1170 - Indwelling blood hydrogen ion concentration (pH) analyzer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Indwelling blood hydrogen ion concentration (pH... Indwelling blood hydrogen ion concentration (pH) analyzer. (a) Identification. An indwelling blood hydrogen ion concentration (pH) analyzer is a device that consists of a catheter-tip pH electrode and that...

  15. 21 CFR 868.1170 - Indwelling blood hydrogen ion concentration (pH) analyzer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Indwelling blood hydrogen ion concentration (pH... Indwelling blood hydrogen ion concentration (pH) analyzer. (a) Identification. An indwelling blood hydrogen ion concentration (pH) analyzer is a device that consists of a catheter-tip pH electrode and that...

  16. A comparison of pH determination methods in food animal practice.

    PubMed Central

    Nappert, G; Naylor, J M

    2001-01-01

    The accuracy of a portable pH meter in measuring blood pH in neonatal calves, urine pH, and ruminal fluid pH in cows has been assessed. Thirty-five diarrheic and 15 healthy beef calves were used for blood gas analysis; 57 healthy dairy cows provided voided urine samples; and ruminal fluid samples were obtained from 10 dairy cows with ruminal fistulas on 4 separate days. Measurements of blood pH were obtained from an automated blood gas analyzer and the portable pH meter. Measurements of urine and ruminal fluid pH were determined with the benchtop pH meter, urinalysis strips, narrow range pH paper, and the portable pH meter. The portable pH meter was more accurate in measuring urine pH and ruminal fluid pH in cows than blood pH in neonatal calves. The urinalysis strips and the narrow range pH paper were found adequate to evaluate urine and ruminal pH. Images Figure 1. PMID:11360858

  17. Post-mortem pH decline in different ostrich muscles.

    PubMed

    Sales, J; Mellett, F D

    1996-01-01

    Post-mortem glycolysis, as described by muscle pH decline, was investigated in several ostrich muscles. While the gastrocnemius pars interna, femorotibialis medius, iliotibialis lateralis and iliofemoralis showed the normal descending pH decline pattern, the ambiens as well as the iliofibularis showed a very rapid pH decline until 2 hr post mortem whereafter pH increased.

  18. 21 CFR 868.1170 - Indwelling blood hydrogen ion concentration (pH) analyzer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Indwelling blood hydrogen ion concentration (pH... Indwelling blood hydrogen ion concentration (pH) analyzer. (a) Identification. An indwelling blood hydrogen ion concentration (pH) analyzer is a device that consists of a catheter-tip pH electrode and that...

  19. pH adjustment schedule for the amide local anesthetics.

    PubMed

    Ikuta, P T; Raza, S M; Durrani, Z; Vasireddy, A R; Winnie, A P; Masters, R W

    1989-01-01

    Several studies have indicated that the addition of sodium bicarbonate to solutions of local anesthetics to raise the pH closer to the pKa shortens the latency, increases the intensity, and prolongs the duration of the resultant neural blockade. However, the addition of too much bicarbonate will cause precipitation, and this may result in the injection of particulate free base along with the solution. The present study was carried out to determine the maximal amount of sodium bicarbonate that can be added to each of the amide local anesthetics without the formation of a precipitate, and, thus, to construct a pH adjustment schedule to simplify the alkalinization of local anesthetics in clinical practice.

  20. Chromatographic hydrophobicity index: pH profile for polyprotic compounds.

    PubMed

    Fuguet, Elisabet; Ràfols, Clara; Bosch, Elisabeth; Rosés, Martí

    2009-11-06

    The Chromatographic Hydrophobicity Index (CHI) has been measured for several diprotic compounds. In order to model the variation of CHI with pH, a general equation for polyprotic compounds which allows the calculation of CHI for each one of the species has been proposed. Different types of diprotic solutes have been selected: neutral acids, neutral bases, and amphiprotic compounds (non-zwitterionic and zwitterionic). The applicability of the model to these complex polyprotic compounds, its advantages and limitations, as well as the information provided by the fits is discussed. In general, the model fits the experimental behaviour of all kind of solutes very well, obtaining the higher hydrophobicity values for the neutral form of the compounds, except for the zwitterionic phenylalanine. The equation and parameters obtained allow an easy calculation of CHI of the compound at any pH value.

  1. Reconstructing Ocean pH with Boron Isotopes in Foraminifera

    NASA Astrophysics Data System (ADS)

    Foster, Gavin L.; Rae, James W. B.

    2016-06-01

    In order to better understand the effect of CO2 on the Earth system in the future, geologists may look to CO2-induced environmental change in Earth's past. Here we describe how CO2 can be reconstructed using the boron isotopic composition (δ11B) of marine calcium carbonate. We review the chemical principles that underlie the proxy, summarize the available calibration data, and detail how boron isotopes can be used to estimate ocean pH and ultimately atmospheric CO2 in the past. δ11B in a variety of marine carbonates shows a coherent relationship with seawater pH, in broad agreement with simple models for this proxy. Offsets between measured and predicted δ11B may in part be explained by physiological influences, though the exact mechanisms of boron incorporation into carbonate remain unknown. Despite these uncertainties, we demonstrate that δ11B may provide crucial constraints on past ocean acidification and atmospheric CO2.

  2. Adsorption of polyetheramines on montmorillonite at high pH.

    PubMed

    Cui, Yannan; van Duijneveldt, Jeroen S

    2010-11-16

    Adsorption of a series of polyetheramines on montmorillonite in aqueous suspension was investigated by a range of methods: elemental analysis, atomic absorption spectroscopy, measurement of pH, conductivity and electrophoretic mobility, and small-angle X-ray scattering. Adsorption proceeds through an ion exchange mechanism. The maximum surface coverage attained is equivalent to about 40% of the cationic exchange capacity of the clay. Adsorption of the poly(oxypropylene) block adjacent to the amine group onto the clay surface may contribute to this. Surprisingly the adsorption takes place at pH conditions well above the pK(a) of the amine surfactants, where they are not protonated in the bulk solution. The surface coverage as a function of molar mass broadly agrees with predictions assuming adsorbed polymers adopt a densely packed mushroom configuration at the clay surface.

  3. Sex differentials in the earnings of Ph.D.s.

    PubMed

    Ferber, M A; Kordick, B

    1978-01-01

    Using a survey of two cohorts of men and women who received Ph.D.s in the years 1958-63 and 1967-72, the authors test two hypotheses: (1) that the relatively lower earnings of highly educated women can be explained largely by their career interruptions and by their lesser willingness to accumulate human capital in anticipation of such interruptions, and (2) that the differential in earnings between men and women increases with age because of career interruptions and that the gap narrows once women reenter the labor force on a permanent basis The findings do not lend support to either of these hypotheses, leading the authors to reject the proposition that the lower rewards of women Ph.D.s are primarily caused by their own voluntary decisions.

  4. Biochar contribution to soil pH buffer capacity

    NASA Astrophysics Data System (ADS)

    Tonutare, Tonu; Krebstein, Kadri; Utso, Maarius; Rodima, Ako; Kolli, Raimo; Shanskiy, Merrit

    2014-05-01

    Biochar as ecologically clean and stable form of carbon has complex of physical and chemical properties which make it a potentially powerful soil amendment (Mutezo, 2013). Therefore during the last decade the biochar application as soil amendment has been a matter for a great number of investigations. For the ecological viewpoint the trend of decreasing of soil organic matter in European agricultural land is a major problem. Society is faced with the task to find possibilities to stabilize or increase soil organic matter content in soil and quality. The availability of different functional groups (e.g. carboxylic, phenolic, acidic, alcoholic, amine, amide) allows soil organic matter to buffer over a wide range of soil pH values (Krull et al. 2004). Therefore the loss of soil organic matter also reduces cation exchange capacity resulting in lower nutrient retention (Kimetu et al. 2008). Biochar can retain elements in soil directly through the negative charge that develops on its surfaces, and this negative charge can buffer acidity in the soil. There are lack of investigations about the effect of biochar to soil pH buffering properties, The aim of our investigation was to investigate the changes in soil pH buffer capacity in a result of addition of carbonizated material to temperate region soils. In the experiment different kind of softwood biochars, activated carbon and different soil types with various organic matter and pH were used. The study soils were Albeluvisols, Leptosols, Cambisols, Regosols and Histosols . In the experiment the series of the soil: biochar mixtures with the biochar content 0 to 100% were used. The times of equiliberation between solid and liquid phase were from 1 to 168 hours. The suspension of soil: biochar mixtures was titrated with HCl solution. The titration curves were established and pH buffer capacities were calculated for the pH interval from 3.0 to 10.0. The results demonstrate the dependence of pH buffer capacity from soil type

  5. Hot Ductility of the 17-4 PH Stainless Steels

    NASA Astrophysics Data System (ADS)

    Herrera Lara, V.; Guerra Fuentes, L.; Covarrubias Alvarado, O.; Salinas Rodriguez, A.; Garcia Sanchez, E.

    2016-03-01

    The mechanisms of loss of hot ductility and the mechanical behavior of 17-4 PH alloys were investigated using hot tensile testing at temperatures between 700 and 1100 °C and strain rates of 10-4, 10-2, and 10-1 s-1. Scanning electron microscopy was used in conjunction with the results of the tensile tests to find the temperature region of loss of ductility and correlate it with cracking observed during processing by hot upsetting prior to ring rolling. It is reported that 17-4 PH alloys lose ductility in a temperature range around 900 °C near to the duplex austenite + ferrite phase field. Furthermore, it is found that niobium carbides precipitated at austenite/ferrite interfaces and grain boundaries have a pronounced effect on the mechanical behavior of the alloy during high-temperature deformation.

  6. Postgraduate research training: the PhD and MD thesis.

    PubMed

    Higginson, I; Corner, J

    1996-04-01

    Higher research degrees, such as the PhD, MPhil and MD, have existed within universities for 80 years or more, although the differences between the MD and PhD remain confused. A higher research degree training provides individuals with greater research knowledge and skills, and benefits the specialty. Concern exists about the levels of supervision sometimes provided, failure to complete degrees, and the variable levels of research knowledge and skills attained. We propose that higher research degrees in palliative care have four functions: extending personal scholarship, generating knowledge, training for the individual and contributing to the growth of the specialty. Such an approach may include: a formalised first year with taught components such as in research MSc programmes, formal supervision and progress assessment. In palliative care, clinical and academic approaches need greater integration. Multiprofessional learning is essential. To allow individuals to undertake higher research degree programmes, fellowships or specific funding are needed.

  7. Flexible high-temperature pH probe

    DOEpatents

    Bielawski, John C.; Outwater, John O.; Halbfinger, George P.

    2003-04-22

    A flexible pH probe device is provided for use in hot water and other high temperature environments up to about 590.degree. F. The pH probe includes a flexible, inert tubular probe member, an oxygen anion conducting, solid state electrolyte plug located at the distal end of the tubular member, oxide powder disposed at the distal end of the tubular member; a metal wire extending along the tubular member and having a distal end in contact with the oxide powder so as to form therewith an internal reference electrode; and a compression fitting forming a pressure boundary seal around a portion of the tubular member remote from the distal end thereof. Preferably, the tubular member is made of polytetrafluoroethylene, and the solid state electrolyte plug is made of stabilized zirconia. The flexibility of the probe member enables placement of the electrode into the area of interest, including around corners, into confined areas and the like.

  8. SAMPLING DEVICE FOR pH MEASUREMENT IN PROCESS STREAMS

    DOEpatents

    Michelson, C.E.; Carson, W.N. Jr.

    1958-11-01

    A pH cell is presented for monitoring the hydrogen ion concentration of a fluid in a process stream. The cell is made of glass with a side entry arm just above a reservoir in which the ends of a glass electrode and a reference electrode are situated. The glass electrode contains the usual internal solution which is connected to a lead. The reference electrode is formed of saturated calomel having a salt bridge in its bottom portion fabricated of a porous glass to insure low electrolyte flow. A flush tube leads into the cell through which buffer and flush solutions are introduced. A ground wire twists about both electrode ends to insure constant electrical grounding of the sample. The electrode leads are electrically connected to a pH meter of aay standard type.

  9. Biona-C Cell Culture pH Monitoring System

    NASA Technical Reports Server (NTRS)

    Friedericks, C.

    1999-01-01

    Sensors 2000! is developing a system to demonstrate the ability to perform accurate, real-time measurements of pH and CO2 in a cell culture media in Space. The BIONA-C Cell Culture pH Monitoring System consists of S2K! developed ion selective sensors and control electronics integrated with the fluidics of a cell culture system. The integrated system comprises a "rail" in the Cell Culture Module (CCM) of WRAIR (Space Biosciences of Walter Read Army Institute of Research). The CCM is a Space Shuttle mid-deck locker experiment payload. The BIONA-C is displayed along with associated graphics and text explanations. The presentation will stimulate interest in development of sensor technology for real-time cell culture measurements. The transfer of this technology to other applications will also be of interest. Additional information is contained in the original document.

  10. Timing of binary and millisecond PKSMB/PH pulsars

    NASA Astrophysics Data System (ADS)

    Eatough, Ralph; Possenti, Andrea; Manchester, Dick; Kramer, Michael; Lyne, Andrew; Hobbs, George; Burgay, Marta; Camilo, Fernando; Stairs, Ingrid; Keith, Michael; Lorimer, Duncan Ross; Jaroenjittichai, Phrudth

    2010-04-01

    This proposal concentrates the timing observations of binary and millisecond pulsars discovered by us in the Parkes Multibeam (PKSMB) and high-latitude (PH) surveys. In order to fully exploit the scientific promises of our discoveries it is essential to perform continued timing observations. It is crucial that the observing sessions be spaced at three-to-five week intervals. The pulsars will be visible during LST 10:00-19:00 and the project should be scheduled within this interval.

  11. Timing of binary and millisecond PKSMB/PH pulsars

    NASA Astrophysics Data System (ADS)

    Eatough, Ralph; Possenti, Andrea; Manchester, Dick; Kramer, Michael; Lyne, Andrew; Hobbs, George; Burgay, Marta; Camilo, Fernando; Stairs, Ingrid; Keith, Michael; Lorimer, Duncan Ross; Jaroenjittichai, Phrudth

    2009-10-01

    This proposal concentrates the timing observations of binary and millisecond pulsars discovered by us in the Parkes Multibeam (PKSMB) and high-latitude (PH) surveys. In order to fully exploit the scientific promises of our discoveries it is essential to perform continued timing observations. It is crucial that the observing sessions be spaced at three-to-five week intervals. The pulsars will be visible during LST 10:00-19:00 and the project should be scheduled within this interval.

  12. Timing of binary and millisecond PKSMB/PH pulsars

    NASA Astrophysics Data System (ADS)

    Eatough, Ralph; Possenti, Andrea; Manchester, Dick; Verbiest, Joris P. W.; Kramer, Michael; Lyne, Andrew; Hobbs, George; Burgay, Marta; Camilo, Fernando; Stairs, Ingrid; Keith, Michael; Lorimer, Duncan Ross

    2010-10-01

    This proposal concentrates the timing observations of binary and millisecond pulsars discovered by us in the Parkes Multibeam (PKSMB) and high-latitude (PH) surveys. In order to fully exploit the scientific promises of our discoveries it is essential to perform continued timing observations. It is crucial that the observing sessions be spaced at three-to-five week intervals. The pulsars will be visible during LST 10:00-19:00 and the project should be scheduled within this interval.

  13. Timing of binary and millisecond PKSMB/PH pulsars

    NASA Astrophysics Data System (ADS)

    Kramer, Michael; Possenti, Andrea; Manchester, Dick; Lyne, Andrew; Hobbs, George; McLaughlin, Maura; Burgay, Marta; D'Amico, Nichi; Camilo, Fernando; Stairs, Ingrid; Faulkner, Andrew; Lorimer, Duncan Ross

    2007-04-01

    This proposal concentrates the timing observations of binary and millisecond pulsars discovered by us in the Parkes Multibeam (PKSMB) and high-latitude (PH) surveys. In order to fully exploit the scientific promises of our discoveries it is essential to perform continued timing observations. It is crucial that the observing sessions be spaced at three-to-five week intervals. The pulsars will be visible during LST 10:00-19:00 and the project should be scheduled within this interval.

  14. Timing of binary and millisecond PKSMB/PH pulsars

    NASA Astrophysics Data System (ADS)

    Kramer, Michael; Possenti, Andrea; Manchester, Dick; Lyne, Andrew; Hobbs, George; McLaughlin, Maura; Burgay, Marta; D'Amico, Nichi; Stairs, Ingrid; Faulkner, Andrew; Eatough, Ralph; Lorimer, Duncan Ross

    2008-04-01

    This proposal concentrates the timing observations of binary and millisecond pulsars discovered by us in the Parkes Multibeam (PKSMB) and high-latitude (PH) surveys. In order to fully exploit the scientific promises of our discoveries it is essential to perform continued timing observations. It is crucial that the observing sessions be spaced at three-to-five week intervals. The pulsars will be visible during LST 10:00-19:00 and the project should be scheduled within this interval.

  15. Timing of binary and millisecond PKSMB/PH pulsars

    NASA Astrophysics Data System (ADS)

    Kramer, Michael; Possenti, Andrea; Manchester, Dick; Lyne, Andrew; Hobbs, George; McLaughlin, Maura; Burgay, Marta; D'Amico, Nichi; Stairs, Ingrid; Faulkner, Andrew; Eatough, Ralph; Lorimer, Duncan Ross

    2007-10-01

    This proposal concentrates the timing observations of binary and millisecond pulsars discovered by us in the Parkes Multibeam (PKSMB) and high-latitude (PH) surveys. In order to fully exploit the scientific promises of our discoveries it is essential to perform continued timing observations. It is crucial that the observing sessions be spaced at three-to-five week intervals. The pulsars will be visible during LST 10:00-19:00 and the project should be scheduled within this interval.

  16. Timing of binary and millisecond PKSMB/PH pulsars

    NASA Astrophysics Data System (ADS)

    Kramer, Michael; Possenti, Andrea; Manchester, Dick; Lyne, Andrew; Hobbs, George; McLaughlin, Maura; Burgay, Marta; D'Amico, Nichi; Camilo, Fernando; Stairs, Ingrid; Faulkner, Andrew; Lorimer, Duncan Ross

    2006-10-01

    This proposal concentrates the timing observations of binary and millisecond pulsars discovered by us in the Parkes Multibeam (PKSMB) and high-latitude (PH) surveys. In order to fully exploit the scientific promises of our discoveries it is essential to perform continued timing observations. It is crucial that the observing sessions be spaced at three-to-five week intervals. The pulsars will be visible during LST 10:00-19:00 and the project should be scheduled within this interval.

  17. Timing of binary and millisecond PKSMB/PH pulsars

    NASA Astrophysics Data System (ADS)

    Eatough, Ralph; Possenti, Andrea; Manchester, Dick; Kramer, Michael; Lyne, Andrew; Hobbs, George; McLaughlin, Maura; Burgay, Marta; D'Amico, Nichi; Stairs, Ingrid; Faulkner, Andrew; Lorimer, Duncan Ross

    2009-04-01

    This proposal concentrates the timing observations of binary and millisecond pulsars discovered by us in the Parkes Multibeam (PKSMB) and high-latitude (PH) surveys. In order to fully exploit the scientific promises of our discoveries it is essential to perform continued timing observations. It is crucial that the observing sessions be spaced at three-to-five week intervals. The pulsars will be visible during LST 10:00-19:00 and the project should be scheduled within this interval.

  18. Lynn Sorbara, PhD | Division of Cancer Prevention

    Cancer.gov

    Dr. Lynn Sorbara earned her PhD from Albert Einstein College of Medicine in 1986. Her thesis research was in the areas of the mechanism of action of the drug, Taxol, and of multidrug resistance. After postdoctoral fellowships at the Rockefeller University and the Mount Sinai College of Medicine in Manhattan, she came to the NIH as a Senior Staff Fellow in the Diabetes Branch of NIDDK. |

  19. Vernon Steele, PhD, MPH | Division of Cancer Prevention

    Cancer.gov

    Dr. Vernon Steele is a Program Director and Group Leader for the Chemoprevention Agent Development Research Group in the NCI Division of Cancer Prevention. He earned his MS and PhD degrees in Radiation Biology at the University of Rochester in 1975 studying radiation effects on cell differentiation. He recently received his Masters of Public Health degree from Johns Hopkins University focusing on environmental toxicology. |

  20. Young Kim, PhD | Division of Cancer Prevention

    Cancer.gov

    Young S Kim, PhD, joined the Division of Cancer Prevention at the National Cancer Institute in 1998 as a Program Director who oversees and monitors NCI grants in the area of Nutrition and Cancer. She serves as an expert in nutrition, molecular biology, and genomics as they relate to cancer prevention. Dr. Kim assists with research initiatives that will advance nutritional science and lead to human health benefits. |

  1. Urinary pH, cigarette smoking and bladder cancer risk

    PubMed Central

    Alguacil, Juan; Kogevinas, Manolis; Silverman, Debra T.; Malats, Núria; Real, Francisco X.; García-Closas, Montserrat; Tardón, Adonina; Rivas, Manuel; Torà, Montserrat; García-Closas, Reina; Serra, Consol; Carrato, Alfredo; Pfeiffer, Ruth M.; Fortuny, Joan; Samanic, Claudine; Rothman, Nathaniel

    2011-01-01

    Glucuronide conjugates of 4-aminobiphenyl and its N-hydroxy metabolite can be rapidly hydrolyzed in acidic urine to undergo further metabolic activation and form DNA adducts in the urothelium. We conducted a large multicenter case–control study in Spain to explore the etiology of bladder cancer and evaluated the association between urine pH and bladder cancer risk, alone and in combination with cigarette smoking. In total, 712 incident urothelial cell carcinoma cases and 611 hospital controls directly measured their urine pH with dipsticks twice a day (first void in the morning and early in the evening) during four consecutive days 2 weeks after hospital discharge. We found that a consistently acidic urine pH ≤6.0 was associated with an increased risk of bladder cancer [odds ratio (OR) = 1.5, 95% confidence interval (CI): 1.2–1.9] compared with all other subjects. Furthermore, risk estimates for smoking intensity and risk of bladder cancer among current smokers tended to be higher for those with a consistently acidic urine (OR = 8.8, 11.5 and 23.8) compared with those without (OR = 4.3, 7.7 and 5.8, respectively, for 1–19, 20–29 and 30+ cigarettes per day; Pinteraction for 30+ cigarettes per day = 0.024). These results suggest that urine pH, which is determined primarily by diet and body surface area, may be an important modifier of smoking and risk of bladder cancer. PMID:21402590

  2. Testing the pH of Soft Drinks

    ERIC Educational Resources Information Center

    Christmann, Edwin P.; Holy, Adam J.

    2005-01-01

    In this article, the authors describe how to use a TI-73/83/84 graphing calculator and Vernier's LabPro/CBL2 probe system to take pH readings. This is not an endorsement of these products, but simply the authors' attempt to give readers an idea of what is involved in using this technology in the classroom. This activity can be accomplished using a…

  3. Iranian PhD student wins human-rights prize

    NASA Astrophysics Data System (ADS)

    Cartwright, Jon

    2013-11-01

    A physicist imprisoned in Iran while on a break from his PhD studies in the US has been awarded a human-rights prize. Omid Kokabee, who had been based at the University of Texas in Austin, has been given the Andrei Sakharov Prize from the American Physical Society (APS) for "his courage in refusing to use his physics knowledge to work on projects that he deemed harmful to humanity, in the face of extreme physical and psychological pressure".

  4. Micellar Enzymology for Thermal, pH, and Solvent Stability.

    PubMed

    Minteer, Shelley D

    2017-01-01

    This chapter describes methods for enzyme stabilization using micellar solutions. Micellar solutions have been shown to increase the thermal stability, as well as the pH and solvent tolerance of enzymes. This field is traditionally referred to as micellar enzymology. This chapter details the use of ionic and nonionic micelles for the stabilization of polyphenol oxidase, lipase, and catalase, although this method could be used with any enzymatic system or enzyme cascade system.

  5. Can anthocyanins improve maintenance therapy of Ph(+) acute lymphoblastic leukaemia?

    PubMed

    Köchling, Joachim; Schmidt, Manuel; Rott, Yvonne; Sagner, Michael; Ungefroren, Hendrik; Wittig, Burghard; Henze, Günter

    2013-04-01

    Chemotherapy and tyrosine kinase inhibitors provide high remission rates. However, prognosis of adult patients with Philadelphia chromosome-positive acute lymphoblastic leukaemia (Ph(+) ALL) still remains poor. Because most adults eventually relapse without allogeneic stem cell transplantation, which is not available for all patients, novel strategies are required for relapse prevention. As the integrity of the immune system is essential for the control of remaining leukaemia cells, we compared the efficacy of anthocyanins, imatinib and a DNA-based vaccine as non-immunosuppressant components with 6-mercaptopurine (6-MP) to control minimal residual disease in vitro and in vivo using different leukaemia cell lines and syngeneic mice. Proliferation of Ph(+) ALL was significantly better inhibited by anthocyanin-rich berry extract or imatinib compared with 6-MP. Although anthocyanins induced apoptosis in some leukaemia cell lines, the level of caspase-3, caspase-8 and caspase-9 was significantly lower compared with imatinib and 6-MP. When used as single components, anthocyanins and imatinib mesylate failed to eradicate pre-existing Ph(+) ALL in syngeneic mice, while 6-MP led to 10% and DNA vaccination to 56% survival. Intriguingly, only the combination of DNA vaccination with berry extract but not with the isolated anthocyanin, cyanidin-3-rutinoside or imatinib further increased leukaemia-free and overall survival, and 90% of lethally challenged mice survived. We suggest that induction and enhancement of a leukaemia-specific immunity by DNA vaccination and anthocyanin-rich berry extract can also decrease the relapse rate in patients with Ph(+) ALL. Furthermore, this approach may serve as strategy for maintenance therapy of other malignancies.

  6. The Research Doctorate in Nursing: The PhD.

    PubMed

    Rice, David

    2016-03-01

    When nurses are considering an advanced degree beyond the master's level of educational preparation, a number of considerations may direct the decision-making process. The doctorate of philosophy (PhD) in nursing is a research degree that will well serve nurses who have the desire to apply theory and develop formal programs of research, become faculty of nursing, combine clinical practice with formal research, and advance through professional leadership in the ranks of hospitals and health systems organizations. 
.

  7. Hala Azzam, PhD, MPH | Division of Cancer Prevention

    Cancer.gov

    Dr. Hala Azzam is a Cancer Epidemiologist in the Cancer Prevention Fellowship Program (CPFP) in the Division of Cancer Prevention within the National Cancer Institute. She received her Bachelor's degree in molecular biology from Kings College London University, her PhD in anatomy and cell biology from Georgetown University Lombardi Cancer Center, and her MPH in epidemiology from Johns Hopkins University. She is also a CPFP alumna. |

  8. Modeling of glucose pH enzyme electrode

    SciTech Connect

    Sarbolouki, M.N.; Ghoorchian, H.; Mozaffari, S. )

    1990-08-01

    Fabrication of a modified glucose pH enzyme electrode, using cellulose acetate instead of cellophane, and its performance are described. A physico-mathematical model that considers glucose transport across the membrane from the bulk into the enzyme solution layer, subsequent proton generation as a consequence of glucose oxidation by the enzyme glucose oxidase, and proton transport back through the membrane into the bulk solution is developed. Proper rate equations are simultaneously solved. Experimental and theoretical results are compared.

  9. A high-throughput colourimetric method for the determination of pH in crystallization screens.

    PubMed

    Kirkwood, Jobie; Wilson, Julie; O'Keefe, Simon; Hargreaves, David

    2014-09-01

    The crystallization of proteins is dependent on the careful control of numerous parameters, one of these being pH. The pH of crystallization is generally reported as that of the buffer; however, the true pH has been found to be as many as four pH units away. Measurement of pH with a meter is time-consuming and requires the reformatting of the crystallization solution. To overcome this, a high-throughput method for pH determination of buffered solutions has been developed with results comparable to those of a pH meter.

  10. Acidic pH environment induces autophagy in osteoblasts

    PubMed Central

    Zhang, Zhichao; Lai, Qingguo; Li, Yanan; Xu, Chao; Tang, Xiaopeng; Ci, Jiangbo; Sun, Shaolong; Xu, Bingbing; Li, Yan

    2017-01-01

    Osteoblasts (OBs) play an important role in bone fracture healing, yet the extreme adverse microenvironment in fracture sites has a negative impact on the survival of OBs. Therefore, it is important to study how OBs behave in the complex fracture microenvironment. Studies have shown that autophagy plays a pivotal role in maintaining cellular homeostasis and defending the cell against adverse microenvironments. In this study we found the induction of autophagy in OBs at femoral bone fracture sites, which may be a result of ischemia, oxidative stress and hypoxia within the local area. At fracture sites a low pH environment also developed. Until now it has been unclear whether the induction of autophagy in osteoblasts is triggered by the acidic pH environment. Therefore, we cultured OBs in vitro in media of different pH values, and found both autophagy and apoptosis increased in OBs in acidic conditions. However, when autophagy inhibitor chloroquine (CQ) was used, apoptosis increased significantly compared with that without CQ. Thus indicating that inhibition of autophagy may promote apoptosis in OBs in an acidic environment, which may provide a new therapeutic strategy to decrease cell apoptosis in OBs through the use of drugs that modulate the autophagic state. PMID:28382973

  11. pH optrode for the complete working range

    NASA Astrophysics Data System (ADS)

    Vishnoi, Gargi; Goel, Tara C.; Pillai, P. K. C.

    1999-01-01

    We report a fast response and inexpensive optical sensor capable of measuring pH in the range of 0.5 to 13.5 units with good resolution. Three indicator dyes viz. Bromocresol Green, Bromothymol Blue and Nile Blue were used to fabricate the sensor head. ion-exchange resin, Amberlite IRA 400, was powdered and immobilized by these dye solutions. In order to prepare sensing membranes, Polyvinyl chloride was dissolved in Tetrahydrofuran and the solution was poured on to a glass plate. Before the membrane was completely dry, the immobilized resin powder was uniformly sprinkled so that the granules are properly glued to it. A bundle of fibers was attached to the membrane mechanically to carry the light from the source to the membrane and collect the reflected optical signal. He-He laser was used as a light source. The experimental results show a linear dependence of pH value on reflected optical signal for the pH range of 0.5 to 13.5 with the resolution of 0.02 unit. The optrode was also characterized by studying the effect of ionic strength and temperature of the solution on the probe response.

  12. Advanced Biotelemetry Systems for Space Life Sciences: PH Telemetry

    NASA Technical Reports Server (NTRS)

    Hines, John W.; Somps, Chris; Ricks, Robert; Kim, Lynn; Connolly, John P. (Technical Monitor)

    1995-01-01

    The SENSORS 2000! (S2K!) program at NASA's Ames Research Center is currently developing a biotelemetry system for monitoring pH and temperature in unrestrained subjects. This activity is part of a broader scope effort to provide an Advanced Biotelemetry System (ABTS) for use in future space life sciences research. Many anticipated research endeavors will require biomedical and biochemical sensors and related instrumentation to make continuous inflight measurements in a variable-gravity environment. Since crew time is limited, automated data acquisition, data processing, data storage, and subject health monitoring are required. An automated biochemical and physiological data acquisition system based on non invasive or implantable biotelemetry technology will meet these requirements. The ABTS will ultimately acquire a variety of physiological measurands including temperature, biopotentials (e.g. ECG, EEG, EMG, EOG), blood pressure, flow and dimensions, as well as chemical and biological parameters including pH. Development activities are planned in evolutionary, leveraged steps. Near-term activities include 1) development of a dual channel pH/temperature telemetry system, and 2) development of a low bandwidth, 4-channel telemetry system, that measures temperature, heart rate, pressure, and pH. This abstract describes the pH/temperature telemeter.

  13. Optoelectronic Instrument Monitors pH in a Culture Medium

    NASA Technical Reports Server (NTRS)

    Anderson, Melody M.; Pellis, Neal; Jeevarajan, Anthony S.; Taylor, Thomas D.

    2004-01-01

    An optoelectronic instrument monitors the pH of an aqueous cell-culture medium in a perfused rotating-wall-vessel bioreactor. The instrument is designed to satisfy the following requirements: It should be able to measure the pH of the medium continuously with an accuracy of 0.1 in the range from 6.5 to 7.5. It should be noninvasive. Any material in contact with the culture medium should be sterilizable as well as nontoxic to the cells to be grown in the medium. The biofilm that inevitably grows on any surface in contact with the medium should not affect the accuracy of the pH measurement. It should be possible to obtain accurate measurements after only one calibration performed prior to a bioreactor cell run. The instrument should be small and lightweight. The instrument includes a quartz cuvette through which the culture medium flows as it is circulated through the bioreactor. The cuvette is sandwiched between light source on one side and a photodetector on the other side. The light source comprises a red and a green light-emitting diode (LED) that are repeatedly flashed in alternation with a cycle time of 5 s. The responses of the photodiode to the green and red LEDs are processed electronically to obtain a quantity proportional to the ratio between the amounts of green and red light transmitted through the medium.

  14. Modeling pH variation in reverse osmosis.

    PubMed

    Nir, Oded; Bishop, Noga Fridman; Lahav, Ori; Freger, Viatcheslav

    2015-12-15

    The transport of hydronium and hydroxide ions through reverse osmosis membranes constitutes a unique case of ionic species characterized by uncommonly high permeabilities. Combined with electromigration, this leads to complex behavior of permeate pH, e.g., negative rejection, as often observed for monovalent ions in nanofiltration of salt mixtures. In this work we employed a rigorous phenomenological approach combined with chemical equilibrium to describe the trans-membrane transport of hydronium and hydroxide ions along with salt transport and calculate the resulting permeate pH. Starting from the Nernst-Planck equation, a full non-linear transport equation was derived, for which an approximate solution was proposed based on the analytical solution previously developed for trace ions in a dominant salt. Using the developed approximate equation, transport coefficients were deduced from experimental results obtained using a spiral wound reverse osmosis module operated under varying permeate flux (2-11 μm/s), NaCl feed concentrations (0.04-0.18 M) and feed pH values (5.5-9.0). The approximate equation agreed well with the experimental results, corroborating the finding that diffusion and electromigration, rather than a priori neglected convection, were the major contributors to the transport of hydronium and hydroxide. The approach presented here has the potential to improve the predictive capacity of reverse osmosis transport models for acid-base species, thereby improving process design/control.

  15. 21 CFR 862.1550 - Urinary pH (nonquantitative) test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Urinary pH (nonquantitative) test system. 862.1550... Systems § 862.1550 Urinary pH (nonquantitative) test system. (a) Identification. A urinary pH (nonquantitative) test system is a device intended to estimate the pH of urine. Estimations of pH are used...

  16. 21 CFR 862.1550 - Urinary pH (nonquantitative) test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Urinary pH (nonquantitative) test system. 862.1550... Systems § 862.1550 Urinary pH (nonquantitative) test system. (a) Identification. A urinary pH (nonquantitative) test system is a device intended to estimate the pH of urine. Estimations of pH are used...

  17. 21 CFR 862.1550 - Urinary pH (nonquantitative) test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Urinary pH (nonquantitative) test system. 862.1550... Systems § 862.1550 Urinary pH (nonquantitative) test system. (a) Identification. A urinary pH (nonquantitative) test system is a device intended to estimate the pH of urine. Estimations of pH are used...

  18. 21 CFR 862.1550 - Urinary pH (nonquantitative) test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Urinary pH (nonquantitative) test system. 862.1550... Systems § 862.1550 Urinary pH (nonquantitative) test system. (a) Identification. A urinary pH (nonquantitative) test system is a device intended to estimate the pH of urine. Estimations of pH are used...

  19. A Two-Level Structural Equation Model for Evaluating the External Effectiveness of PhD

    ERIC Educational Resources Information Center

    Chiandotto, Bruno; Masserini, Lucio

    2011-01-01

    In recent years the number of PhDs in Italy has significantly grown and purposes of PhD courses have expanded from the traditional ones. The analysis of the contribution of PhD title for job placement and employment condition of PhDs is an important tool for evaluating the quality and the effectiveness of PhD courses. For this reason, knowledge of…

  20. 21 CFR 862.1550 - Urinary pH (nonquantitative) test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Urinary pH (nonquantitative) test system. 862.1550... Systems § 862.1550 Urinary pH (nonquantitative) test system. (a) Identification. A urinary pH (nonquantitative) test system is a device intended to estimate the pH of urine. Estimations of pH are used...

  1. A single design strategy for dual sensitive pH probe with a suitable range to map pH in living cells

    PubMed Central

    Yu, Kang-Kang; Hou, Ji-Ting; Li, Kun; Yao, Qian; Yang, Jin; Wu, Ming-Yu; Xie, Yong-Mei; Yu, Xiao-Qi

    2015-01-01

    Due to the lack of a proper imaging approach, a veracious pH map of normal and abnormal cell is still rare. In this work, we presented a rhodamine-salicylaldehyde combination (Rh-SA2) as a novel pH probe, which has dual sensitive units for both acidic and basic environment. This dual sensitive probe acts like a chameleon in living cells and offers the doubling guarantees for endocellular pH mapping. Moreover, a quantitative measurement of cellular pH changes was allowed and the endocellular pH values under drug-associated stimuli were also investigated. PMID:26486180

  2. Diiron species containing a cyclic P(Ph)2N(Ph)2 diphosphine related to the [FeFe]H2ases active site.

    PubMed

    Lounissi, Sondès; Capon, Jean-François; Gloaguen, Frédéric; Matoussi, Fatma; Pétillon, François Y; Schollhammer, Philippe; Talarmin, Jean

    2011-01-21

    A new dissymmetrically disubstituted diiron dithiolate species, [Fe(2)(CO)(4)(κ(2)-P(Ph)(2)N(Ph)(2))(μ-pdt)] (pdt = S(CH(2))(3)S), was prepared by using a flexible cyclic base-containing diphosphine, 1,3,5,7-tetraphenyl 1,5-diaza-3,7-diphosphacyclooctane (P(Ph)(2)N(Ph)(2) = {PhPCH(2)NPh}(2)). Preliminary investigations of proton and electron transfers on the diiron system have been done.

  3. Influence of pH on transungual passive and iontophoretic transport.

    PubMed

    Smith, Kelly A; Hao, Jinsong; Li, S Kevin

    2010-04-01

    The present study investigated the effects of pH on nail permeability and the transport of ions such as sodium (Na) and chloride (Cl) ions endogenous to nail and hydronium and hydroxide ions present at low and high pH, which might compete with drug transport across hydrated nail plate during iontophoresis. Nail hydration and passive transport of water across the nail at pH 1-13 were assessed. Subsequently, passive and iontophoretic transport experiments were conducted using (22)Na and (36)Cl ions under various pH conditions. Nail hydration was independent of pH under moderate pH conditions and increased significantly under extreme pH conditions (pH >11). Likewise, nail permeability for water was pH independent at pH 1-10 and an order of magnitude higher at pH 13. The results of passive and iontophoretic transport of Na and Cl ions are consistent with the permselective property of nail. Interestingly, extremely acidic conditions (e.g., pH 1) altered nail permselectivity with the effect lasting several days at the higher pH conditions. Hydronium and hydroxide ion competition in iontophoretic transport was generally negligible at pH 3-11 was significant at the extreme pH conditions studied.

  4. A geometric process model for M/PH(M/PH)/1/K queue with new service machine procurement lead time

    NASA Astrophysics Data System (ADS)

    Yu, Miaomiao; Tang, Yinghui; Fu, Yonghong

    2013-06-01

    In this article, we consider a geometric process model for M/PH(M/PH)/1/K queue with new service machine procurement lead time. A maintenance policy (N - 1, N) based on the number of failures of the service machine is introduced into the system. Assuming that a failed service machine after repair will not be 'as good as new', and the spare service machine for replacement is only available by an order. More specifically, we suppose that the procurement lead time for delivering the spare service machine follows a phase-type (PH) distribution. Under such assumptions, we apply the matrix-analytic method to develop the steady state probabilities of the system, and then we obtain some system performance measures. Finally, employing an important Lemma, the explicit expression of the long-run average cost rate for the service machine is derived, and the direct search method is also implemented to determine the optimal value of N for minimising the average cost rate.

  5. Molecular Characterization and Functional Analysis of Two Petunia PhEILs

    PubMed Central

    Liu, Feng; Hu, Li; Cai, Yuanping; Lin, Hong; Liu, Juanxu; Yu, Yixun

    2016-01-01

    Ethylene plays an important role in flower senescence of many plants. Arabidopsis ETHYLENE INSENSITIVE3 (EIN3) and its homolog EIL1 are the downstream component of ethylene signaling transduction. However, the function of EILs during flower senescence remains unknown. Here, a petunia EIL gene, PhEIL2, was isolated. Phylogenetic tree showed that PhEIL1, whose coding gene is previously isolated, and PhEIL2 are the homologs of Arabidopsis AtEIL3 and AtEIL1, respectively. The expression of both PhEIL1 and PhEIL2 is the highest in corollas and increased during corolla senescence. Ethylene treatment increased the mRNA level of PhEIL1 but reduced that of PhEIL2. VIGS-mediated both PhEIL1 and PhEIL2 silencing delayed flower senescence, and significantly reduced ethylene production and the expression of PhERF3 and PhCP2, two senescence-associated genes in petunia flowers. The PhEIL2 protein activating transcription domain is identified in the 353-612-amino acids at C-terminal of PhEIL2 and yeast two-hybrid and bimolecular fluorescence complementation assays show that PhEIL2 interacts with PhEIL1, suggesting that PhEIL1 and PhEIL2 might form heterodimers to recognize their targets. These molecular characterizations of PhEIL1 and PhEIL2 in petunia are different with those of in Vigna radiata and Arabidopsis. PMID:27847510

  6. Optimal pH control of batch processes for production of curdlan by Agrobacterium species.

    PubMed

    Lee; Lee; Kim; Park

    1999-08-01

    We sought an optimal pH profile to maximize curdlan production in a batch fermentation of Agrobacterium species. The optimal pH profile was calculated using a gradient iteration algorithm based on the minimum principle of Pontryagin. The model equations describing cell growth and curdlan production were developed as functions of pH, sucrose concentration, and ammonium concentration, since the specific rates of cell growth and curdlan production were highly influenced by those parameters. The pH profile provided the strategy to shift the culture pH from the optimal growth condition (pH 7.0) to the optimal production one (pH 5.5) at the time of ammonium exhaustion. By applying the optimal pH profile in the batch process, we obtained significant improvement in curdlan production (64 g L-1) compared to that of constant pH operation (36 g L-1).

  7. INFLUENCE OF PH ON RECOVERY OF MYCOPLASMA FROM THE HUMAN OROPHARYNX.

    DTIC Science & Technology

    methylene blue . Positive cultures in the first group were as follows: 78% at pH 5.0, 94% at pH 6.0, 88% at pH 7.0, and 78% at pH 8.0. Highest incidence of M. pharyngis occurred at pH 7.0 and of M. salivarium at pH 5.0 and 6.0. The one M. hominis type 1 isolate grew evenly over the entire range of pH tested. In the second group, a pH of 7.0 and 8.0 was optimal for the recovery of M. pneumoniae. It was concluded that, excepting M. pneumoniae, the human oral mycoplasmas are more frequently isolated on PPLO agar of pH 6.0 and 7.0.

  8. A revision of the genus Atelecrinus PH Carpenter (Echinodermata: Crinoidea).

    PubMed

    Messing, Charles G

    2013-01-01

    The unusual bathyal comatulid crinoid genus Atelecrinus is widespread in the Atlantic and tropical Pacific Oceans and currently includes three recognized species. A re-assessment based on examination of new and existing specimens requires establishment of two new genera and five new species, and returns three junior synonyms to species-level status. Paratelecrinus is erected to accommodate Atelecrinus wyvilli PH Carpenter, A. conifer AH Clark, A. cubensis PH Carpenter, P. orthotriremis, new species, P. amenouzume new species, P. laticonulus new species and P. telo new species. Adelatelecrinus is erected to accommodate Atelecrinus sulcatus AH Clark and Adelatelecrinus vallatus new species. Atelecrinus retains A. balanoides PH Carpenter and A. helgae AH Clark, which restricts the genus to the Atlantic. In both Paratelecrinus and Adelatelecrinus, the basals articulate with the centrodorsal via ligament bundles anchored in deep ringlike interradial pits that project into the centrodorsal cavity, whereas in Atelecrinus the centrodorsal rim has shallow interradial concavities and attaches to the basals via a tight junction with no obvious ligament bundles. The spoon-shaped aboral fossa in the basals of Paratelecrinus appears to be unique among articulate crinoids and differs from the smooth fossa found in both Atelecrinus and Adelatelecrinus. New material extends the range of the family to the Indian Ocean. A few species are now known from enough specimens to identify some ontogenetic and distributional variations. Proximal ray morphology varies substantially with size in P. cubensis and P. orthotriremis. A. balanoides generally occurs in deeper water in the Lesser Antilles than in the Bahamas and Strait of Florida, while P. orthotriremis occurs in shallower water in the Lesser Antilles and deeper in the Bahamas.

  9. Leonard F. Peltier, MD, PhD, 1920-2003.

    PubMed

    Reckling, Frederick W; Lo Vecchio, Janolyn G; Reckling, JoAnn B

    2004-05-01

    Leonard F. Peltier, MD, PhD, was an orthopaedic surgeon, academician, administrator, laboratory investigator, historian, and mentor. His career spanned nearly six decades, beginning with graduate education at the University of Minnesota (UM) under the auspices of Owen H. Wangensteen, MD, PhD. In addition to obtaining a PhD in physiology in the UM Graduate School, he completed general and orthopaedic surgery residencies and attained board certification in each specialty. He served in the US Army Occupation Force Medical Corps in Germany just after World War II. In 1957, at 37 years old, he assumed the chairmanship of the orthopaedic training program at the University of Kansas. In 1971, he couldn't resist the opportunity to become one of the founding members of the "start-up" University of Arizona College of Medicine, accepting an appointment as chair of the new orthopaedic training program, where he remained until his retirement in 1990. He took clinical problems to the laboratory, and made important scientific contributions, particularly in the area of fat embolism and in using calcium sulfate (plaster of Paris) to fill bone defects. He served on governing boards of national professional organizations and presided over the American Association for the Surgery of Trauma from 1980-1981. Throughout his career, he was fascinated by, and published extensively in, the history of medicine arena. Known fondly as "the professor" to many of his residents and colleagues, he had a pragmatic, honest, upbeat, and often humorous approach to life's challenges, valuing personal integrity above other virtues. He explored various eclectic interests far beyond his professional contributions while maintaining his family as a central priority. With his exemplary productivity and interests in the surgical and laboratory sciences, history of medicine, appreciation of fine arts, and perceptive and effective interactions with family, friends, patients, and colleagues, the memory of Leonard

  10. Timing of binary and millisecond PKSMB/PH pulsars

    NASA Astrophysics Data System (ADS)

    Kramer, Michael; Possenti, Andrea; Manchester, Dick; Lyne, Andrew; Hobbs, George; McLaughlin, Maura; Burgay, Marta; D'Amico, Nichi; Camilo, Fernando; Stairs, Ingrid; Faulkner, Andrew; Lorimer, Duncan Ross

    2006-04-01

    This proposal consolidates and concentrates the timing observations of binary and millisecond pulsars discovered by us in the Parkes Multibeam (PKSMB) and high-latitude (PH) surveys. In order to fully exploit the scientific promises of our discoveries it is essential to perform continued timing observations. It is crucial that the observing sessions be spaced at three-to-five week intervals. The pulsars will be visible during LST 08:30 -- 22:30 and the project should be scheduled within this interval.

  11. Timing of binary and millisecond PKSMB/PH pulsars

    NASA Astrophysics Data System (ADS)

    Kramer, Michael; Possenti, Andrea; Manchester, Dick; Lyne, Andrew; Hobbs, George; McLaughlin, Maura; Burgay, Marta; D'Amico, Nichi; Stairs, Ingrid; Faulkner, Andrew; Eatough, Ralph; Lorimer, Duncan Ross

    2008-10-01

    This proposal concentrates the timing observations of binary and millisecond pulsars discovered by us in the Parkes Multibeam (PKSMB) and high-latitude (PH) surveys. This session we have also incorporated P417, timing of a new class of pulsars, into this proposal. In order to fully exploit the scientific promises of our discoveries it is essential to perform continued timing observations. It is crucial that the observing sessions be spaced at three-to-five week intervals. The pulsars will be visible during LST 05:00-19:00 and the project should be scheduled within this interval.

  12. Peptide hydrogelation triggered by enzymatic induced pH switch

    NASA Astrophysics Data System (ADS)

    Cheng, Wei; Li, Ying

    2016-07-01

    It remains challenging to develop methods that can precisely control the self-assembling kinetics and thermodynamics of peptide hydrogelators to achieve hydrogels with optimal properties. Here we report the hydrogelation of peptide hydrogelators by an enzymatically induced pH switch, which involves the combination of glucose oxidase and catalase with D-glucose as the substrate, in which both the gelation kinetics and thermodynamics can be controlled by the concentrations of D-glucose. This novel hydrogelation method could result in hydrogels with higher mechanical stability and lower hydrogelation concentrations. We further illustrate the application of this hydrogelation method to differentiate different D-glucose levels.

  13. Plaque pH modulations of children's favourite snacks.

    PubMed

    Gauba, K; Goyal, A; Tewari, A

    1991-03-01

    Cariogenic potential of a few children's favourite snacks, assessed by evaluation of pH modulations on their respective consumption after 2,5,10,20,30 and 40 minutes compared to 10 percent sucrose control using pooled plaque method, in 8-12 years old children revealed lollipop (hard sucking candy) to be the most cariogenic and samosa without chutney to be the least cariogenic. The cariogenic potential of ice creams were similar, however, low as compared to sucrose solution of 10 percent.

  14. Complaints against an EMS system.

    PubMed

    Colwell, Christopher B; Pons, Peter T; Pi, Randy

    2003-11-01

    Complaints against Emergency Medical Services (EMS) agencies represent a concerning and potentially time-consuming problem for all involved in the delivery of prehospital emergency medical care. The objective of this study was to identify the source of complaints against an EMS system to help focus quality and performance improvement and customer service efforts. We conducted a retrospective review of complaints filed against a busy urban EMS agency over a 6-year period. All complaints were included, totaled by season and by year, and categorized by originator and nature of the complaint. A total of 286 complaints were registered during the 6-year period, with an average of 48 per year and 9.3 per 10,000 responses. The most common originators of complaints were patients (53%) followed by medical personnel (19%) and family members or friends (12%). Rude behavior accounted for 23% of the complaints registered, followed by technical skills (20%), transport problems (18%), and loss of belongings (13%). The identification of areas of dissatisfaction will allow focused quality and performance improvement programs directed at customer service and risk management.

  15. [A questionnaire study among 171 medical candidates enrolled in a PhD program. Three elements in the PhD education: supervision, research courses and international relations].

    PubMed

    Hauge, E M; Grønbaek, H

    1998-11-02

    One hundred and seventy-one medical doctors (median age 34 years) registered as Ph.D.-students at the Medical Faculty, University of Aarhus, were given a questionnaire concerning the Ph.D-program (91% reply rate). The Ph.D.-students had typically graduated four years before enrollment and had gained basic clinical experience. Eighty-four percent had been involved in research projects prior to their formal research education. In general, the Ph.D.-students found the supervision offered by senior researchers adequate, although, more Ph.D.-students in clinical than in preclinical departments would have liked their main supervisor to be more enthusiastic and have more specific expertise. By tradition, the Medical Faculty in Aarhus offers a broad introductory course on research methodology, this was appreciated by the Ph.D.-students. However, they found that too much time was allocated for this purpose. The Ministry of Education recommends that Ph.D.-students gain experience from international collaboration, preferably from a stay abroad. However, only 24% of Ph.D.-students had stayed at an international collaborating institution. Although the overall evaluation of the medical Ph.d.-program was positive, the Ph.D.-students pointed out weaknesses and conflicts requiring adjustment.

  16. pH Shifting alters solubility characteristics and thermal stability of soy protein isolate and its globulin fractions in different pH, salt concentration, and temperature conditions.

    PubMed

    Jiang, Jiang; Xiong, Youling L; Chen, Jie

    2010-07-14

    Soy protein isolate (SPI), beta-conglycinin (7S), and glycinin (11S) were subjected to pH-shifting treatments, that is, unfolding at pH 1.5 or 12.0 followed by refolding at pH 7.0, to induce molten globule structures. Treated samples were analyzed for protein solubility, thermal stability, and aggregation in 0, 0.1, and 0.6 M NaCl solutions at pH 2.0-8.0. The pH(12) shifting resulted in drastic increases (up to 2.5-fold) in SPI solubility in the pH 6.0-7.0 range, especially at 0 M NaCl. The pH(1.5) shifting had a generally lesser effect on solubility. 11S exhibited a solubility pattern similar to that of SPI, but the solubility of 7S was unaffected by pH shifting except at 0.6 M NaCl. The pH shifting, notably at pH 12.0, produced soluble, disulfide-linked polymers from 11S and reduced (P < 0.05) its enthalpy but not its temperature of denaturation. Soy proteins structurally altered by pH shifting had a reduced sensitivity to thermal aggregation.

  17. Interacting effects of pH acclimation, and pH and heavy metals on acute and chronic toxicity to Ceriodaphnia dubia (Cladocera)

    SciTech Connect

    Belanger, S.E.; Cherry, D.S. )

    1990-05-01

    Understanding the factors that modify the sensitivity of the zooplankton Ceriodaphnia dubia to toxicants is important to the interpretation of chronic toxicity data generated for granting industrial permits. Early reports of high sensitivity of Ceriodaphnia to brief pH excursions led toxicologists to question the use of C. dubia as a test organism. Acute and chronic toxicity of pH and heavy metals, pH acclimation to acidic and alkaline conditions and the role of pH in modifying heavy metal (copper and zinc) toxicities were investigated. Ceriodaphnia dubia acclimated near neutral pH had acute (48-hr) lethal concentrations of 4.6 and 10.3 SU. Reproduction and mortality were not impaired between pH 6.14-8.99 regardless of pH acclimation history. Reproduction was significantly impaired beyond these extremes. Acute exposures to both heavy metals at pH 6, 8 and 9 and in water hardness of 180, 110 and 100 mg/L showed C dubia was consistently most sensitive in low pH and low hardness waters. Reproduction and mortality were not so affected by pH in chronic exposures. Similar concentrations of metals at all pH levels resulted in equivalent reductions in offspring per female. The results strongly suggest that effluent guidelines for pH at 6-9 are sound, and that toxicant activity in chronic time frames is directed primarily by concentration and water hardness, not by pH. 34 refs., 2 figs., 8 tabs.

  18. Objectives and Assessment of the NMSU Physics Ph.D. program

    NASA Astrophysics Data System (ADS)

    Zollner, Stefan

    2012-03-01

    New Mexico State University (NMSU) in Las Cruces, NM, is accredited by the Higher Learning Commission (HLC) and a member of the North Central Association of Colleges and Schools (NCA). As part of our continuous accreditation, the physics department annually assesses its progress towards goals and objectives. Our academic goals include the development of skills pertinent to solving advanced problems in physics, a mastery of advanced concepts in physics, an in-depth knowledge of one or more subfields, and develop the ability to conduct original research in a specialization. These goals are supported by objectives, including scientific expertise, advanced training, experimental training, communication skills, and technical know-how. We measure one direct student learning outcome, the ability to solve advanced problems in general physics subjects. The instrument for this measurement is our written physics comprehensive (Ph.D. candidacy) exam, which is administered by an examination committee consisting of all faculty members. We report annually on the percentage of students passing the exam in the various areas (QM, mechanics, E&M, Stat. Mech.). Ineffective preparation of our students in one area would show up by unusually low scores in that area. Since the problems are written and graded by all faculty (not just by those who taught the class), this provides an independent assessment of student learning and also evidence by other professionals skilled in the field. Our examinations are similar to published exams at other institutions. The results of the exam provide feedback to the course instructors, to the students, and to the department head who schedules instructors and courses. In some cases, retaking a course has been a condition of passing the exam for a student. (I acknowledge the efforts of Gary Kyle, who has managed our assessment for many years, and of the entire NMSU physics faculty for contributing to this process.)

  19. Re-designing the PhEDEx Security Model

    SciTech Connect

    Huang, C.-H.; Wildish, T.; Zhang, X.

    2014-01-01

    PhEDEx, the data-placement tool used by the CMS experiment at the LHC, was conceived in a more trusting time. The security model provided a safe environment for site agents and operators, but offerred little more protection than that. Data was not sufficiently protected against loss caused by operator error or software bugs or by deliberate manipulation of the database. Operators were given high levels of access to the database, beyond what was actually needed to accomplish their tasks. This exposed them to the risk of suspicion should an incident occur. Multiple implementations of the security model led to difficulties maintaining code, which can lead to degredation of security over time. In order to meet the simultaneous goals of protecting CMS data, protecting the operators from undue exposure to risk, increasing monitoring capabilities and improving maintainability of the security model, the PhEDEx security model was redesigned and re-implemented. Security was moved from the application layer into the database itself, fine-grained access roles were established, and tools and procedures created to control the evolution of the security model over time. In this paper we describe this work, we describe the deployment of the new security model, and we show how these enhancements improve security on several fronts simultaneously.

  20. Effects of ph, carbonate, orthophosphate, and redox potential on cuprosolvency

    SciTech Connect

    Schock, M.R.; Lytle, D.A.; Clement, J.A.

    1995-12-01

    A comprehensive solubility model for copper in drinking water has been developed, that is consistent with available data for copper dissolution and passivation in drinking water systems. Copper solubility (cuprosolvency) is greatly affected by the redox conditions of the systems. The concentration of Cu(I) is dominated by Cu{sub 2}O(s) or CuOH(s) solid phases, plus soluble aqueous ammonia and chloride complexes. In new piping, the concentration of Cu(II) is mainly governed by Cu(OH){sub 2}(s) (cupric hydroxide), rather than CuO(s) (tenorite) or Cu{sub 2}(OH){sub 2}CO{sub 3}(s)(malachite). Complexation of Cu(II) by DIC and hydroxide ion is extremely important. Increases in DIC are predicted to cause significant increases in copper solubility in the pH range of 7.5--10. Utilities may trade off increasing cuprosolvency by DIC addition for ensuring adequate buffering intensity in the finished water. Sufficient dosages of orthophosphate in the pH range of 6.5 to 7.5 may reduce cuprosolvency under oxidizing conditions. Sulfate may decrease cuprosolvency under some conditions, or may interfere with the formation of cupric hydroxide films under mildly alkaline conditions. Dissolved oxygen and chlorine residual play complicated roles in determining copper concentrations after various standing times. Frequently, 48--72 hours are necessary to reach equilibrium levels of copper in disinfected systems.

  1. Hydrazone linkages in pH responsive drug delivery systems.

    PubMed

    Sonawane, Sandeep J; Kalhapure, Rahul S; Govender, Thirumala

    2017-03-01

    Stimuli-responsive polymeric drug delivery systems using various triggers to release the drug at the sites have become a major focus area. Among various stimuli-responsive materials, pH-responsiveness has been studied extensively. The materials used for fabricating pH-responsive drug delivery systems include a specific chemical functionality in their structure that can respond to changes in the pH of the surrounding environment. Various chemical functionalities, for example, acetal, amine, ortho ester, amine and hydrazone, have been used to design materials that are capable of releasing their payload at the acidic pH conditions of the tumor or infection sites. Hydrazone linkages are significant synthons for numerous transformations and have gained importance in pharmaceutical sciences due to their various biological and clinical applications. These linkages have been employed in various drug delivery vehicles, such as linear polymers, star shaped polymers, dendrimers, micelles, liposomes and inorganic nanoparticles, for pH-responsive drug delivery. This review paper focuses on the synthesis and characterization methods of hydrazone bond containing materials and their applications in pH-responsive drug delivery systems. It provides detailed suggestions as guidelines to materials and formulation scientists for designing biocompatible pH-responsive materials with hydrazone linkages and identifying future studies.

  2. Near-Neutral pH SCC Crack Initiation Studies

    NASA Astrophysics Data System (ADS)

    Hiebert, John

    4-Point bend studies on X-52 linepipe steel with ''natural'' surfaces (sigmamax = 95% SMYS, f = 0.001 Hz, R = 0.6) in synthetic soil solutions indicate that crack initiation and transgranular crack formation occurs more readily in C2 solutions than in C4 solutions. This increase is associated with solution compositions that increase general corrosion rates and that reduce the precipitation of carbonates. When it is assumed that relative differences in bulk solution properties are manifested at the crack tip, then these differences may promote a more favourable environment for crack tip dissolution, ion transport, and microplastic deformation. Although the results are not definitive, in these studies the development of longer and transgranular cracks appear to be associated more with differences in solution composition than with differences in surface finish. Increased corrosion and hydrogen permeation rates are associated with increased proton, carbonic acid, and bicarbonate ion concentrations and not explicitly with lower pH. Calculations show, at open circuit corrosion conditions, that FeCO3 precipitation can limit pH increases.

  3. Histidine oxidation photosensitized by pterin: pH dependent mechanism.

    PubMed

    Castaño, Carolina; Oliveros, Esther; Thomas, Andrés H; Lorente, Carolina

    2015-12-01

    Aromatic pterins accumulate in the skin of patients suffering from vitiligo, a chronic depigmentation disorder, due to the oxidation of tetrahydrobiopterin, the biologically active form of pterins. In this work, we have investigated the ability of pterin, the parent compound of aromatic pterins, to photosensitize the oxidation of histidine in aqueous solutions under UV-A irradiation. Histidine is an α-amino acid with an imidazole functional group, and is frequently present at the active sites of enzymes. The results highlight the role of the pH in controlling the competition between energy and electron transfer mechanisms. It has been previously demonstrated that pterins participate as sensitizers in photosensitized oxidations, both by type I (electron-transfer) and type II mechanisms (singlet oxygen ((1)O2)). By combining different analytical techniques, we could establish that a type I photooxidation was the prevailing mechanism at acidic pH, although a type II mechanism is also present, but it is more important in alkaline solutions.

  4. Seawater pH at the advent of metazoan calcification

    NASA Astrophysics Data System (ADS)

    Ries, Justin; Gonzalez-Roubaud, Cécile; Douville, Eric; Montagna, Paolo

    2016-04-01

    The boron isotopic composition (δ11B) of bulk limestones provides a potentially powerful tool for reconstructing seawater pH deep into the geologic past (Kasemann et al., 2005; Paris et al., 2010; Ohnemueller et al., 2014). Here, we present δ11B of 35 calcitic limestones derived from a ca. 9 m.y. interval of the terminal Proterozoic Nama Group of southern Namibia. These units immediately precede the so-called Cambrian Radiation - the greatest diversification of metazoans in Earth history marked by the near-simultaneous advent of calcification across most animal phyla. The Nama Group represents one of the best preserved (average [Sr] = 1805 ppm; Mn/Sr < 2; δ18O > -10‰) and most continuous terminal Proterozoic limestone sequences known in the world. The carbonate units investigated here were deposited between ca. 552 and 543 Ma in a semi-divided foreland basin of the Kalahari Craton (Grotzinger and Miller, 2008). Depositional environments were shore-associated and ranged from upper shoreline/tidal flats to below-wave-base lower shoreface, and comprise calcisiltites, calcarenites, heterolithic interbeds, grainstones, and microbialites (Saylor et al., 1998; Grotzinger and Miller, 2008). The δ11B of the 35 sampled Nama Group carbonates were obtained via MC-ICP-MS. Samples were screened for contamination of the δ11B signal by clays (using [Al] as a proxy for clay content) (Paris et al., 2010) and by open-system meteoric diagenesis (δ11B-δ18O correlation). The δ11B values of the limestones ranged from 0.5 to 10.8‰ (avg. = 5.3‰), which is consistent with the previously observed increasing trend in carbonate δ11B (Paris et al., 2010) from the -6.2 to 2.7‰ values reported for Neoproterozoic cap carbonate dolostones (Kasemann et al., 2005) to the ca. 25‰ value reported for most modern marine carbonates. B/Ca ratios for the sampled limestones ranged from 3.4 to 24.0 ppm (avg. = 11.0). Assuming a seawater temperature of 25° C, a salinity of 35, a depth of 10

  5. Intrathylakoid pH in Isolated Pea Chloroplasts as Probed by Violaxanthin Deepoxidation.

    PubMed Central

    Pfundel, E. E.; Renganathan, M.; Gilmore, A. M.; Yamamoto, H. Y.; Dilley, R. A.

    1994-01-01

    Light-driven violaxanthin deepoxidation was measured in isolated pea (Pisum sativum) chloroplasts without ATP synthesis (basal conditions) and with ATP synthesis (coupled conditions). Thylakoids stored in high salt (HS) or low salt (LS) storage medium were tested. In previous experiments, HS thylakoids and LS thylakoids were related to delocalized and localized proton coupling, respectively.Light-driven deepoxidase activity was compared to the pH dependence of deepoxidase activity established in dark reactions. At an external pH of 8, light-driven deepoxidation indicated effective pH values close to pH 6 for all reaction conditions. Parallel to deepoxidation, the thylakoid lumen pH was estimated by the fluorescent dye pyranine.In LS thylakoids under coupled conditions the lumen pH did not drop below pH 6.7. At pH 6.7, no deepoxidase activity is expected based on the pH dependence of enzyme activity. The results suggest that deepoxidation activity is controlled by the pH in sequestered membrane domains, which, under localized proton coupling, can be maintained at pH 6.0 when the lumen pH is far above pH 6.0. The extent of violaxanthin conversion (availability), however, appeared to be regulated by lumenal pH. Dithiothreitol-sensitive nonphotochemical quenching of chlorophyll fluorescence was dependent on zeaxanthin and not related to lumenal pH. Thus, zeaxanthin-dependent quenching[mdash]known to be pH dependent[mdash]appeared to be triggered by the pH of localized membrane domains. PMID:12232439

  6. Modeling the low pH limit of Nitrosomonas eutropha in high-strength nitrogen wastewaters.

    PubMed

    Fumasoli, Alexandra; Morgenroth, Eberhard; Udert, Kai M

    2015-10-15

    In wastewater treatment, the rate of ammonia oxidation decreases with pH and stops very often slightly below a pH of 6. Free ammonia (NH3) limitation, inhibition by nitrous acid (HNO2), limitation by inorganic carbon or direct effect of high proton concentrations have been proposed to cause the rate decrease with pH as well as the cessation of ammonia oxidation. In this study, we compare an exponential pH term common for food microbiology with conventionally applied rate laws based on Monod-type kinetics for NH3 limitation and non-competitive HNO2 inhibition as well as sigmoidal pH functions to model the low pH limit of ammonia oxidizing bacteria (AOB). For this purpose we conducted well controlled batch experiments which were then simulated with a computer model. The results showed that kinetics based on NH3 limitation and HNO2 inhibition can explain the rate decrease of ammonia oxidation between pH 7 and 6, but fail in predicting the pH limit of Nitrosomonas eutropha at pH 5.4 and rates close to that limit. This is where the exponential pH term becomes important: this term decreases the rate of ammonia oxidation to zero, as the pH limit approaches. Previously proposed sigmoidal pH functions that affect large pH regions, however, led to an overestimation of the pH effect and could therefore not be applied successfully. We show that the proposed exponential pH term can be explained quantitatively with thermodynamic principles: at low pH values, the energy available from the proton motive force is too small for the NADH production in Nitrosomonas eutropha and related AOB causing an energy limited state of the bacterial cell. Hence, energy limitation and not inhibition or limitation of enzymes is responsible for the cessation of the AOB activity at low pH values.

  7. Influence of pH Regulation Mode in Glucose Fermentation on Product Selection and Process Stability

    PubMed Central

    Mohd-Zaki, Zuhaida; Bastidas-Oyanedel, Juan R.; Lu, Yang; Hoelzle, Robert; Pratt, Steven; Slater, Fran R.; Batstone, Damien J.

    2016-01-01

    Mixed culture anaerobic fermentation generates a wide range of products from simple sugars, and is potentially an effective process for producing renewable commodity chemicals. However it is difficult to predict product spectrum, and to control the process. One of the key control handles is pH, but the response is commonly dependent on culture history. In this work, we assess the impact of pH regulation mode on the product spectrum. Two regulation modes were applied: in the first, pH was adjusted from 4.5 to 8.5 in progressive steps of 0.5 and in the second, covered the same pH range, but the pH was reset to 5.5 before each change. Acetate, butyrate, and ethanol were produced throughout all pH ranges, but there was a shift from butyrate at pH < 6.5 to ethanol at pH > 6.5, as well as a strong and consistent shift from hydrogen to formate as pH increased. Microbial analysis indicated that progressive pH resulted in dominance by Klebsiella, while reset pH resulted in a bias towards Clostridium spp., particularly at low pH, with higher variance in community between different pH levels. Reset pH was more responsive to changes in pH, and analysis of Gibbs free energy indicated that the reset pH experiments operated closer to thermodynamic equilibrium, particularly with respect to the formate/hydrogen balance. This may indicate that periodically resetting pH conforms better to thermodynamic expectations. PMID:27681895

  8. Detrimental effects of reduced seawater pH on the early development of the Pacific abalone.

    PubMed

    Li, Jiaqi; Jiang, Zengjie; Zhang, Jihong; Qiu, Jian-Wen; Du, Meirong; Bian, Dapeng; Fang, Jianguang

    2013-09-15

    The hatching process of the Pacific abalone Haliotis discus hannai was prolonged at a pH of 7.6 and pH 7.3, and the embryonic developmental success was reduced. The hatching rate at pH 7.3 was significantly (10.8%) lower than that of the control (pH 8.2). The malformation rates at pH 7.9 and pH 8.2 were less than 20% but were 53.8% and 77.3% at pH 7.6 and pH 7.3, respectively. When newly hatched larvae were incubated for 48 h at pH 7.3, only 2.7% of the larvae settled, while more than 70% of the larvae completed settlement in the other three pH treatments. However, most 24 h old larvae could complete metamorphosis in all four pH treatments. Overall, a 0.3-unit reduction in water pH will produce no negative effect on the early development of the Pacific abalone, but further reduction in pH to the values predicted for seawater by the end of this century will have strong detrimental effects.

  9. Technical note: development and testing of a radio transmission pH measurement system for continuous monitoring of ruminal pH in cows.

    PubMed

    Sato, Shigeru; Mizuguchi, Hitoshi; Ito, Kazunori; Ikuta, Kentaro; Kimura, Atushi; Okada, Keiji

    2012-03-01

    An indwelling ruminal pH system has been used for the continuous recording of ruminal pH to evaluate subacute ruminal acidosis (SARA) in dairy cows. However this system does not allow the field application. The objective of this study was to develop a new radio transmission pH measurement system, and to assess its performance and usefulness in a continuous evaluation of ruminal pH for use on commercial dairy farms. The radio transmission pH measurement system consists of a wireless pH sensor, a data measurement receiver, a relay unit, and a personal computer installed special software. The pH sensor is housed in a bullet shaped bolus, which also encloses a pH amplifier circuit, a central processing unit (CPU) circuit, a radio frequency (RF) circuit, and a battery. The mean variations of the measurements by the glass pH electrode were +0.20 (n=10) after 2 months of continuous recording, compared to the values confirmed by standard pH solutions for pH 4 and pH 7 at the start of the recording. The mean lifetime of the internal battery was 2.5 months (n=10) when measurements were continuously transmitted every 10 min. Ruminal pH recorded by our new system was compared to that of the spot sampling of ruminal fluid. The mean pH for spot sampling was 6.36 ± 0.55 (n=96), and the mean pH of continuous recording was 6.22 ± 0.54 (n=96). There was a good correlation between continuous recording and spot sampling (r=0.986, P<0.01). We also examined whether our new pH system was able to detect experimentally induced ruminal acidosis in cows and to record long-term changes in ruminal pH. In the cows fed acidosis-inducing diets, the ruminal pH dropped markedly during the first 2h following the morning feeding, and decreased moreover following the evening feeding, with many pulse-like pH changes. The pH of the cows showed the lowest values of 5.3-5.2 in the midnight time period and it recovered to the normal value by the next morning feeding. In one healthy periparturient cow

  10. Direct reduction of N-acetoxy-PhIP by tea polyphenols: a possible mechanism for chemoprevention against PhIP-DNA adduct formation.

    PubMed

    Lin, Dong-Xin; Thompson, Patricia A; Teitel, Candee; Chen, Jun-Shi; Kadlubar, Fred F

    2003-01-01

    The chemopreventive effect of tea against 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-DNA adduct formation and its mechanism were studied. Rats were exposed to freshly prepared aqueous extracts of green tea (3% (w/v)) as the sole source of drinking water for 10 days prior to administration with a single dose of PhIP (10 mg/kg body weight) by oral gavage. PhIP-DNA adducts in the liver, colon, heart, and lung were measured using the 32P-postlabelling technique. Rats pre-treated with tea and given PhIP 20 h before sacrifice had significantly reduced levels of PhIP-DNA adducts as compared with controls given PhIP alone. The possible mechanism of protective effect of tea on PhIP-DNA adduct formation was then examined in vitro. It was found that an aqueous extract of green and black tea, mixtures of green and black tea polyphenols, as well as purified polyphenols could strongly inhibit the DNA binding of N-acetoxy-PhIP, a putative ultimate carcinogen of PhIP formed in vivo via metabolic activation. Among these, epigallocatechin gallate was exceptionally potent. HPLC analyses of these incubation mixtures containing N-acetoxy-PhIP and the tea polyphenols each revealed the production of the parent amine, PhIP, indicating the involvement of a redox mechanism. In view of the presence of relatively high levels of tea polyphenols in rat and human plasma after ingestion of tea, this study suggests that direct reduction of the ultimate carcinogen N-acetoxy-PhIP by tea polyphenols is likely to be involved in the mechanism of chemoprotection of tea against this carcinogen.

  11. Selective formation of the [PhP(H)-PPh]- anion in the reaction of PhPHLi with MeAlCl(2); synthesis and structure of the unusual tetramer [(PhP(H)-PPh)Li.thf]4.

    PubMed

    Garcia, Felipe; Humphrey, Simon M; Kowenicki, Richard A; McPartlin, Mary; Wright, Dominic S

    2004-04-07

    The reaction of PhPHLi with MeAlCl(2)(3:1 equivalents) gives the tetramer [(PhP(H)-PPh)Li.thf]4, and provides the first direct evidence of a link between the reactivity patterns observed for Group 14 and 15 phosphanenides and those of Group 13.

  12. In vivo intracellular pH measurements in tobacco and Arabidopsis reveal an unexpected pH gradient in the endomembrane system.

    PubMed

    Martinière, Alexandre; Bassil, Elias; Jublanc, Elodie; Alcon, Carine; Reguera, Maria; Sentenac, Hervé; Blumwald, Eduardo; Paris, Nadine

    2013-10-01

    The pH homeostasis of endomembranes is essential for cellular functions. In order to provide direct pH measurements in the endomembrane system lumen, we targeted genetically encoded ratiometric pH sensors to the cytosol, the endoplasmic reticulum, and the trans-Golgi, or the compartments labeled by the vacuolar sorting receptor (VSR), which includes the trans-Golgi network and prevacuoles. Using noninvasive live-cell imaging to measure pH, we show that a gradual acidification from the endoplasmic reticulum to the lytic vacuole exists, in both tobacco (Nicotiana tabacum) epidermal (ΔpH -1.5) and Arabidopsis thaliana root cells (ΔpH -2.1). The average pH in VSR compartments was intermediate between that of the trans-Golgi and the vacuole. Combining pH measurements with in vivo colocalization experiments, we found that the trans-Golgi network had an acidic pH of 6.1, while the prevacuole and late prevacuole were both more alkaline, with pH of 6.6 and 7.1, respectively. We also showed that endosomal pH, and subsequently vacuolar trafficking of soluble proteins, requires both vacuolar-type H(+) ATPase-dependent acidification as well as proton efflux mediated at least by the activity of endosomal sodium/proton NHX-type antiporters.

  13. A temperature independent pH (TIP) buffer for biomedical biophysical applications at low temperatures.

    PubMed

    Sieracki, Nathan A; Hwang, Hee Jung; Lee, Michelle K; Garner, Dewain K; Lu, Yi

    2008-02-21

    A temperature independent pH buffer has been developed from a combination of buffers of opposite-sign temperature coefficients, and utility in low temperature spectroscopy and storage of pH sensitive compounds is demonstrated.

  14. Responding to a Problem: A W.P.A. for Ph.Ds?

    ERIC Educational Resources Information Center

    Mattson, Kevin

    2002-01-01

    Takes a fresh look at the humanities Ph.D. glut and suggests a unique approach that would put Ph.D.s to work while enriching society as a whole: something reminiscent of the Works Progress Administration (WPA). (EV)

  15. Similarities in pheromonal communication of flea beetles Phyllotreta cruciferae Goeze and Ph. vittula Redtenbacher (Coleoptera, Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Remarkable similarities have been found in the pheromonal communication of Phyllotreta vittula Redtenbacher and of Ph. cruciferae Goeze (European population) (Coleoptera, Chrysomelidae). In previous European field tests with Ph. cruciferae, only the major male-produced sesquiterpene identified from ...

  16. pH Sensitive Microcapsules for Delivery of Corrosion Inhibitors

    NASA Technical Reports Server (NTRS)

    Li, Wenyan; Calle, Luz M.

    2006-01-01

    A considerable number of corrosion problems can be solved by coatings. However, even the best protective coatings can fail by allowing the slow diffusion of oxygen and moisture to the metal surface. Corrosion accelerates when a coating delaminates. Often, the problems start when microscopic nicks or pits on the surface develop during manufacturing or through wear and tear. This problem can be solved by the incorporation of a self-healing function into the coating. Several new concepts are currently under development to incorporate this function into a coating. Conductive polymers, nanoparticles, and microcapsules are used to release corrosion-inhibiting ions at a defect site. The objective of this investigation is to develop a smart coating for the early detection and inhibition of corrosion. The dual function of this new smart coating system is performed by pH-triggered release microcapsules. The microcapsules can be used to deliver healing agents to terminate the corrosion process at its early stage or as corrosion indicators by releasing dyes at the localized corrosion sites. The dyes can be color dyes or fluorescent dyes, with or without pH sensitivity. Microcapsules were formed through the interfacial polymerization process. The average size of the microcapsules can be adjusted from 1 to 100 micron by adjusting the emulsion formula and the microcapsule forming conditions. A typical microcapsule size is around 10 microns with a narrow size distribution. The pH sensitivity of the microcapsule can also be controlled by adjusting the emulsion formula and the polymerization reaction time. Both corrosion indicator (pH indicator) and corrosion inhibitor containing microcapsules were formed and incorporated into paint systems. Test panels of selected steels and aluminum alloys were painted using these paints. Testing of compatibility between the microcapsule system and different paint systems are in progress. Initial experiments with the microcapsule containing paint

  17. Early Careers of Recent U.S. Social Science PhDs

    ERIC Educational Resources Information Center

    Morrison, Emory; Rudd, Elizabeth; Nerad, Maresi

    2011-01-01

    In this article, we analyse findings of the largest, most comprehensive survey of the career paths of social science PhD graduates to date, "Social Science PhDs--Five+Years Out (SS5)". "SS5" surveyed more than 3,000 graduates of U.S. PhD programmes in six social science fields six to ten years after earning their PhD. The…

  18. The Purpose of the Ph.D.--A South African Perspective

    ERIC Educational Resources Information Center

    Herman, Chaya

    2012-01-01

    The article sets out to explore how Ph.D. programme leaders in South Africa view the purpose of the Ph.D., and how their views shape their responses to recent policies with regard to the Ph.D. It refers in particular to the vision of the Department of Science and Technology for a five-fold increase in the number of Ph.D. graduates by 2018, and to…

  19. Nitrification Enhancement through pH Control with Rotating Biological Contactors

    DTIC Science & Technology

    1981-09-01

    Inst. of Sew. Purif., 130 (1964). 31. Engel, M. S. and M. Alexander, " Growth and Autotrophic Metabolism of Nitrosomonas Europaea ," Jour. Bact., 76, 217...relative effectiveness of four different alkaline chemicals on enhancing the nitrifying process under optimum pH conditions was evaluated in Phase II...111 6.12 Relative RBC Heterotrophic Bacteria Growth Under pH Conditions from pH 7.0 to pH 8.5 ....... ............. .. 112 6.13 Batch Alkalinity

  20. 40 CFR 420.07 - Effluent limitations guidelines and standards for pH.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... standards for pH. 420.07 Section 420.07 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... § 420.07 Effluent limitations guidelines and standards for pH. (a) The pH level in process wastewaters subject to a subpart within this part shall be within the range of 6.0 to 9.0. (b) The pH level shall...

  1. DOE/EM Criticality Safety Needs Assessment

    SciTech Connect

    Westfall, Robert Michael; Hopper, Calvin Mitchell

    2011-02-01

    The issue of nuclear criticality safety (NCS) in Department of Energy Environmental Management (DOE/EM) fissionable material operations presents challenges because of the large quantities of material present in the facilities and equipment that are committed to storage and/or material conditioning and dispositioning processes. Given the uncertainty associated with the material and conditions for many DOE/EM fissionable material operations, ensuring safety while maintaining operational efficiency requires the application of the most-effective criticality safety practices. In turn, more-efficient implementation of these practices can be achieved if the best NCS technologies are utilized. In 2002, DOE/EM-1 commissioned a survey of criticality safety technical needs at the major EM sites. These needs were documented in the report Analysis of Nuclear Criticality Safety Technology Supporting the Environmental Management Program, issued May 2002. Subsequent to this study, EM safety management personnel made a commitment to applying the best and latest criticality safety technology, as described by the DOE Nuclear Criticality Safety Program (NCSP). Over the past 7 years, this commitment has enabled the transfer of several new technologies to EM operations. In 2008, it was decided to broaden the basis of the EM NCS needs assessment to include not only current needs for technologies but also NCS operational areas with potential for improvements in controls, analysis, and regulations. A series of NCS workshops has been conducted over the past years, and needs have been identified and addressed by EM staff and contractor personnel. These workshops were organized and conducted by the EM Criticality Safety Program Manager with administrative and technical support by staff at Oak Ridge National Laboratory (ORNL). This report records the progress made in identifying the needs, determining the approaches for addressing these needs, and assimilating new NCS technologies into EM

  2. Preparing the future of astronomy PhDs in France

    NASA Astrophysics Data System (ADS)

    Boissier, S.; Buat, V.; Cambresy, L.

    2015-12-01

    The numbers of doctors in astronomy formed in France has been increasing for 15 years, a time during which the number of openings for permanent positions has remained constant. As it is well known by the young generations, the pressure on the research position is high, putting many post-doctoral researchers in difficult situations for up to 10 years after their defence. We have to prepare students and post-doctoral researchers to maximize their chances for both academia and the private sector. In this spirit, the 2015 SF2A conference included a lunch meeting with former members of hiring committee and a workshop on the valorization of the astronomy thesis. We believe awareness of both young and senior researchers is important to provide PhDs with a robust background and modern methods, valuable in their future, whichever it is.

  3. pH dependence of antibody/lysozyme complexation.

    PubMed

    Gibas, C J; Subramaniam, S; McCammon, J A; Braden, B C; Poljak, R J

    1997-12-16

    Association between proteins often depends on the pH and ionic strength conditions of the medium in which it takes place. This is especially true in complexation involving titratable residues at the complex interface. Continuum electrostatics methods were used to calculate the pH-dependent energetics of association of hen egg lysozyme with two closely related monoclonal antibodies raised against it and the association of these antibodies against an avian species variant. A detailed analysis of the energetic contributions reveals that even though the hallmark of association in the two complexes is the presence of conserved charged-residue interactions, the environment of these interactions significantly influences the titration behavior and concomitantly the energetics. The contributing factors include minor structural rearrangements, buried interfacial area, dielectric environment of the key titratable residues, and geometry of the residue dispositions. Modeled structures of several mutant complexes were also studied so as to further delineate the contribution of individual factors to the titration behavior.

  4. Mentored peer reviewing for PhD faculty and students.

    PubMed

    Xu, Jiayun; Kim, Kyounghae; Kurtz, Melissa; Nolan, Marie T

    2016-02-01

    There is a need for scholars to be prepared as peer reviewers in order to ensure the continual publication of quality science. However, developing the skills to craft a constructive critique can be difficult. In this commentary, we discuss the use of a group peer review mentoring model for PhD students to gain experience in peer review from a faculty member who is experienced in peer review. Central to this model, was the opportunity for each student and faculty mentor to openly discuss their critique of the manuscript. Through this enriching experience, novice researchers were able to learn the elements of a good peer review, better determine a manuscript's substantive contribution to science, and advance the quality of their own manuscript writing.

  5. The future of astronomy PhDs in France

    NASA Astrophysics Data System (ADS)

    Boissier, S.

    2012-12-01

    This contribution presents a poll undertaken at the beginning of 2012, and addressed to every doctor in astronomy who obtained his/her degree in France. Its goal is to motivate the French astronomical community to think and discuss about what should be the training of PhDs, and what should be its objective. Further discussions and reactions can be posted e.g. on {http://docastro.blogspot.fr/}. A worrying results from the poll is that the majority of the participants would not encourage a young student to start a thesis in astronomy. The main reasons for this fact may be the high pressure on astronomy positions and the little interest a doctorate has for other careers in France. I suggest we either have to modify our training or reduce the number of thesis starting each year in astronomy.

  6. Astrobites: The Astro-ph Reader's Digest For Undergraduates

    NASA Astrophysics Data System (ADS)

    Vasel, Justin; Faesi, Chris; Drout, Maria; Newton, Elisabeth

    2013-04-01

    Astrobites (http://astrobites.com) is a daily blog aimed primarily at undergraduates interested in astrophysical research and written by a team of graduate students located at institutions around the world. Nearly every day we present a journal article recently posted to astro-ph in a brief format that is accessible to anyone with a general background in the physical sciences. In addition to summarizing new work, Astrobites provides valuable context for readers not yet familiar with the some of the background concepts and jargon present in the astrophysical literature. Special posts offer career guidance for undergraduates (e.g. applying for an NSF graduate fellowship) and describe personal experiences (e.g. attending an astronomy summer school). The readership of astrobites has grown dramatically since our founding in fall of 2010, with individuals now accessing the site from 104 countries worldwide. We will discuss the Astrobites format, recent readership statistics, and future planned initiatives.

  7. Astrobites: The Astro-ph Reader's Digest For Undergraduates

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna; Astrobites Team

    2013-04-01

    Astrobites (http://astrobites.com) is a daily blog aimed primarily at undergraduates interested in astrophysical research and written by a team of graduate students located at diverse institutions around the world. Nearly every day we present a journal article recently posted to astro-ph in a brief format that is accessible to anyone with a general background in the physical sciences. In addition to summarizing new work, Astrobites provides valuable context for readers not yet familiar with the astrophysical literature. Special posts offer career guidance for undergraduates (e.g. applying for an NSF graduate fellowship) and describe personal experiences (e.g. attending an astronomy summer school). We will discuss the Astrobites format and recent readership statistics, as well as potential methods for incorporating Astrobites into the classroom.

  8. Astrobites: The Astro-ph Reader's Digest For Undergraduates

    NASA Astrophysics Data System (ADS)

    Drout, Maria; Vasel, J. A.; Dressing, C. D.; Gifford, D.; Morley, C.; Hall, S.; Newton, E. R.; Astrobites Team

    2013-01-01

    Astrobites (http://astrobites.com) is a daily blog aimed primarily at undergraduates interested in astrophysical research and written by a team of graduate students located at institutions around the world. Nearly every day we present a journal article recently posted to astro-ph in a brief format that is accessible to anyone with a general background in the physical sciences. In addition to summarizing new work, Astrobites provides valuable context for readers not yet familiar with the some of the background concepts and jargon present in the astrophysical literature. Special posts offer career guidance for undergraduates (e.g. applying for an NSF graduate fellowship) and describe personal experiences (e.g. attending an astronomy summer school). The readership of astrobites has grown dramatically since our founding in fall of 2010, with individuals now accessing the site from 104 countries worldwide. We will discuss the Astrobites format, recent readership statistics, and future planned initiatives.

  9. Astrobites: The Astro-ph Reader's Digest For Undergraduates

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna; Weiss, L. M.; Faesi, C. M.; Astrobites Team

    2012-05-01

    Astrobites (http://astrobites.com) is a daily blog aimed primarily at undergraduates interested in astrophysical research and written by a team of graduate students located at diverse institutes around the country and Europe. Every day we present a journal article recently posted to astro-ph in a brief format that is accessible to anyone with a general background in the physical sciences. In addition to summarizing new work, Astrobites provides valuable context for readers not yet familiar with the astrophysical literature. Special posts offer career guidance for undergraduates (e.g. applying for an NSF graduate fellowship) and describe personal experiences (e.g. attending an astronomy summer school). We will discuss the Astrobites format and recent readership statistics.

  10. Updates from Astrobites: The Astro-ph Reader's Digest

    NASA Astrophysics Data System (ADS)

    Montet, Benjamin; Chisari, N.; Donaldson, J.; Dressing, C. D.; Drout, M.; Faesi, C.; Fuchs, J. T.; Kohler, S.; Lovegrove, E.; Mills, E. A.; Nesvold, E.; Newton, E. R.; Olmstead, A.; Vasel, J. A.; Weiss, L. M.; Astrobites Team

    2014-01-01

    Astrobites (http://astrobites.com) is a daily blog aimed at undergraduates interested in astrophysical research and written by a team of graduate students located at diverse institutions across the United States. Primarily, we present journal articles recently posted to astro-ph in a brief format that is accessible to anyone with a general background in the physical sciences, including readers who are not yet familiar with the astrophysical literature. Special posts offer career guidance for undergraduates (e.g. applying for an NSF graduate fellowship) and describe personal experiences (e.g. attending an astronomy summer school). We present recent readership statistics and potential methods for incorporating Astrobites into the classroom. We also discuss the Astrobites format across multiple social media platforms, including the newly launched Astroplots, and highlight our recent work organizing the annual "Communicating Science" workshop for graduate students.

  11. pH Responsive Microcapsules for Corrosion Control

    NASA Technical Reports Server (NTRS)

    Calle, Luz Marina; Li, Wenyan; Muehlberg, Aaron; Boraas, Samuel; Webster, Dean; JohnstonGelling, Victoria; Croll, Stuart; Taylor, S Ray; Contu, Francesco

    2008-01-01

    The best coatings for corrosion protection provide not only barriers to the environment, but also a controlled release of a corrosion inhibitor, as demanded by the presence of corrosion or mechanical damage. NASA has developed pH sensitive microcapsules (patent pending) that can release their core contents when corrosion starts. The objectives of the research presented here were to encapsulate non-toxic corrosion inhibitors, to incorporate the encapsulated inhibitors into paint formulations, and to test the ability of the paints to control corrosion. Results showed that the encapsulated corrosion inhibitors, specifically Ce(NO3)3 , are effective to control corrosion over long periods of time when incorporated at relatively high pigment volume concentrations into a paint formulation.

  12. International PhD Students in Australian Universities: Financial Support, Course Experience and Career Plans

    ERIC Educational Resources Information Center

    Harman, G.

    2003-01-01

    Using data from a social survey of PhD students in two major Australian universities supplemented by student interviews, this article reports on the financial support, course experience and career plans of international PhD students. While most international PhD students hold scholarships which include stipends, a minority of students experience…

  13. Cadmium triggers Elodea canadensis to change the surrounding water pH and thereby Cd uptake.

    PubMed

    Javed, M Tariq; Greger, Maria

    2011-01-01

    This study was aimed to investigate the influence of Elodea canadensis shoots on surrounding water pH in the presence of cadmium and the effect of plant-induced pH on cadmium uptake. The pH change in the surrounding nutrient solution and Cd uptake by Elodea shoots were investigated after cultivation of various plant densities (1, 3, 6 plants per 500 ml) in hydroponics at a starting pH of 4.0 and in the presence of different concentrations of cadmium (0, 0.1, 0.5 microM). Cadmium uptake was also investigated at different constant pH (4.0, 4.5, 5.5 and 6.5). To investigate if the pH change arose from photosynthetic activities, plants were grown under light, darkness or in the presence of a photosynthetic inhibitor, 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), and 0.5 microM cadmium in the solution. Elodea had an ability to increase the surrounding water pH, when the initial pH was low, which resulted in increased accumulation of Cd. The higher the plant density, the more pronounced was the pH change. The pH increase was not due to the photosynthetic activity since the pH rise was more pronounced under darkness and in the presence of DCMU. The pH increase by Elodea was triggered by cadmium.

  14. Hyperpolarised organic phosphates as NMR reporters of compartmental pH.

    PubMed

    Jensen, Pernille Rose; Meier, Sebastian

    2016-02-07

    Organic phosphate metabolites contain functional groups with pKa values near the physiologic pH range, yielding pH-dependent (13)C chemical shift changes of adjacent quaternary carbon sites. When formed in defined cellular compartments from exogenous hyperpolarised (13)C substrates, metabolites can thus yield localised pH values and correlations of organelle pH and catalytic activity.

  15. 40 CFR 401.17 - pH Effluent limitations under continuous monitoring.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 30 2013-07-01 2012-07-01 true pH Effluent limitations under... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS GENERAL PROVISIONS § 401.17 pH Effluent limitations under continuous monitoring. (a) Where a permittee continuously measures the pH of wastewater pursuant to...

  16. 40 CFR 434.62 - Alternate effluent limitation for pH.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 30 2014-07-01 2014-07-01 false Alternate effluent limitation for pH... SOURCE PERFORMANCE STANDARDS Miscellaneous Provisions § 434.62 Alternate effluent limitation for pH... comply with the otherwise applicable manganese limitations, the permit issuer may allow the pH level...

  17. 40 CFR 432.3 - General limitation or standard for pH.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 30 2014-07-01 2014-07-01 false General limitation or standard for pH... limitation or standard for pH. Any discharge subject to BPT, BCT, or NSPS limitations or standards in this part must remain within the pH range of 6 to 9....

  18. 40 CFR 401.17 - pH Effluent limitations under continuous monitoring.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 29 2014-07-01 2012-07-01 true pH Effluent limitations under... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS GENERAL PROVISIONS § 401.17 pH Effluent limitations under continuous monitoring. (a) Where a permittee continuously measures the pH of wastewater pursuant to...

  19. 40 CFR 401.17 - pH Effluent limitations under continuous monitoring.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 30 2012-07-01 2012-07-01 false pH Effluent limitations under... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS GENERAL PROVISIONS § 401.17 pH Effluent limitations under continuous monitoring. (a) Where a permittee continuously measures the pH of wastewater pursuant to...

  20. 40 CFR 434.62 - Alternate effluent limitation for pH.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 31 2012-07-01 2012-07-01 false Alternate effluent limitation for pH... SOURCE PERFORMANCE STANDARDS Miscellaneous Provisions § 434.62 Alternate effluent limitation for pH... comply with the otherwise applicable manganese limitations, the permit issuer may allow the pH level...

  1. 40 CFR 434.62 - Alternate effluent limitation for pH.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 31 2013-07-01 2013-07-01 false Alternate effluent limitation for pH... SOURCE PERFORMANCE STANDARDS Miscellaneous Provisions § 434.62 Alternate effluent limitation for pH... comply with the otherwise applicable manganese limitations, the permit issuer may allow the pH level...

  2. 40 CFR 432.3 - General limitation or standard for pH.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 31 2012-07-01 2012-07-01 false General limitation or standard for pH... limitation or standard for pH. Any discharge subject to BPT, BCT, or NSPS limitations or standards in this part must remain within the pH range of 6 to 9....

  3. 40 CFR 432.3 - General limitation or standard for pH.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 30 2011-07-01 2011-07-01 false General limitation or standard for pH... standard for pH. Any discharge subject to BPT, BCT, or NSPS limitations or standards in this part must remain within the pH range of 6 to 9....

  4. 40 CFR 432.3 - General limitation or standard for pH.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 31 2013-07-01 2013-07-01 false General limitation or standard for pH... limitation or standard for pH. Any discharge subject to BPT, BCT, or NSPS limitations or standards in this part must remain within the pH range of 6 to 9....

  5. 40 CFR 434.62 - Alternate effluent limitation for pH.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 30 2011-07-01 2011-07-01 false Alternate effluent limitation for pH... PERFORMANCE STANDARDS Miscellaneous Provisions § 434.62 Alternate effluent limitation for pH. Where the... otherwise applicable manganese limitations, the permit issuer may allow the pH level in the final...

  6. Completing PhDs: The Perils and Enduring Promise of Deep Study

    ERIC Educational Resources Information Center

    Butler, Jon

    2009-01-01

    What is a PhD? People answer this question too often by succumbing to the bureaucratic lure. They describe formal processes, "outcomes", time to degree, funding, training in teaching--indeed, almost everything except central intellectual attraction and personal focus of the PhD enterprise: deep study. Certainly in United States PhD programs, the…

  7. Trust Me, I'm a Doctor: A PhD Survival Guide

    ERIC Educational Resources Information Center

    Deconinck, Koen

    2015-01-01

    So, you have decided to do a PhD … now what? In this essay, the author provides some advice for beginning PhD students, basically sharing what he would tell his younger self. Doing a PhD is a transformative experience, but the process is challenging, not merely on an intellectual level but also psychologically. To overcome these challenges, one…

  8. Are PhDs Winners or Losers? Wage Premiums for Doctoral Degrees in Private Sector Employment

    ERIC Educational Resources Information Center

    Pedersen, Heidi Skovgaard

    2016-01-01

    Policy makers expect increasing numbers of PhDs to find employment in the private sector. However, the incentive structure for completing a PhD and subsequently seeking private sector employment has not been adequately assessed in the literature. This paper investigates the financial incentives for this career choice of recent Danish PhD…

  9. Continuous intra-arterial blood pH monitoring by a fiber-optic fluorosensor.

    PubMed

    Jin, Weizhong; Wu, Lingxiang; Song, Yuanlin; Jiang, Jinjun; Zhu, Xiaodan; Yang, Dawei; Bai, Chunxue

    2011-05-01

    Continuous intra-arterial blood pH monitoring is highly desirable in clinical practice. However, devices with appreciable accuracy are still not commercially available to date. In this study, we present a fiber-optic fluorosensor that can be used to continuously and accurately measure blood pH changes. The pH sensor is developed based on a proton-sensitive fluorescence dye, N-allyl-4-(4'-methyl-piperazinyl)-1,8-naphthalimide, which is bonded covalently to an optical fiber through heat polymerization. Fluorescence intensity was recorded after the sensor was exposed to different pH buffer solutions or intra-arterial blood in rabbits. Fluorescence intensity with emission peak at 510 nm decreased immediately as the blood pH increased. Linear and reproducible responses were observed when pH ranges from 6.8 to 8.0 with resolution of 0.03 pH units. The correlation coefficient between the pH sensor and the conventional blood gas analyzer was 0.93 in vivo ( n=75, p<0.001) with a bias and precision of -0.02 ± 0.08 pH units. The pH sensor was stable during measurement for at least 72 h. The pH sensor is not sensitive to fluctuations of various ions' concentrations and plasma osmosis at pathophysiological limits, suggesting that it is useful for the continuous measurement of blood pH at various clinical settings.

  10. Determination of pH in regions of the midguts of acaridid mites.

    PubMed

    Erban, Tomas; Hubert, Jan

    2010-01-01

    The pH of the guts of mites strongly affects their digestive processes. This study was carried out to determine the pH in the guts of 12 species of stored product and house dust mites. Eighteen pH indicators were chosen and offered to the mites in the feeding biotest. Based on the color changes of the indicators, the gut contents of acaridid mites were determined to be within a pH range of 4 to neutral. The gut contents showed a gradient in pH from the anterior to the posterior part. The anterior midgut (ventriculus and caeca) of most species had a pH ranging from 4.5 to 5, or slightly more alkaline for most of the species, while the middle midgut (intercolon/colon) had a pH of 5 to 6. Finally, the pH of the posterior midgut (postcolon) was between 5.5 and 7. Except for Dermatophagoides spp., no remarkable differences in the pH of the gut were observed among the tested species. Dermatophagoides spp. had a more acidic anterior midgut (a pH of 4 to 5) and colon (a pH of 5) with postcolon (a pH of below 6). The results characterizing in vivo conditions in the mite gut offer useful information to study the activity of mite digestive enzymes including their inhibitors and gut microflora.

  11. A variable stoichiometry model for pH homeostasis in bacteria.

    PubMed Central

    Macnab, R M; Castle, A M

    1987-01-01

    The composition of the proton-motive force of a hypothetical bacterial cell of wide pH tolerance is analyzed according to a model whereby the electron transport chain and various proton-linked sodium and potassium ion transporting modes are responsible for the development of the membrane potential and the chemical potentials of the three cations. Simultaneous use of two or more modes employing the same metal cation, but at a different stoichiometric ratio with respect to protons, produces nonintegral stoichiometry; the modes could represent either different devices or different states of a single device. Cycling of the cation, driven by proton-motive force, results. The relative conductances of the various modes are postulated to be pH-dependent. The pattern of potentials that results is qualitatively in accord with current knowledge and may reflect the mechanism of pH homeostasis in bacteria. The membrane potential is outwardly directed (positive inside) at extremely acid pH, becoming inwardly directed as the pH increases; the pH gradient across the membrane is large and inwardly directed (alkaline inside) at acid pH, becoming smaller and eventually inverting at alkaline pH values; the transmembrane potassium gradient is outwardly directed (high concentration inside) at all pH values; the transmembrane sodium gradient is inwardly directed at all pH values, following the pH gradient from acid through neutral pH, but then diverging at alkaline pH. PMID:3676443

  12. "A 'Problem' to Be Managed?" Completing a PhD in the Arts and Humanities

    ERIC Educational Resources Information Center

    Owler, Kathryn

    2010-01-01

    Driven largely by efficiency imperatives, many universities have come to adopt a managerialist approach to research over the last several years. University administrators have become actively concerned with the traditionally long times taken to complete a PhD and high attrition rates. Consequently, the PhD, and PhD students' experience of struggle…

  13. Review on State-of-the-art in Polymer Based pH Sensors

    PubMed Central

    Korostynska, Olga; Arshak, Khalil; Gill, Edric; Arshak, Arousian

    2007-01-01

    This paper reviews current state-of-the-art methods of measuring pH levels that are based on polymer materials. These include polymer-coated fibre optic sensors, devices with electrodes modified with pH-sensitive polymers, fluorescent pH indicators, potentiometric pH sensors as well as sensors that use combinatory approach for ion concentration monitoring.

  14. Undertaking Individual Transdisciplinary PhD Research for Sustainable Development: Case Studies from South Africa

    ERIC Educational Resources Information Center

    van Breda, John; Musango, Josephine; Brent, Alan

    2016-01-01

    Purpose: This paper aims to improve the understanding of individual transdisciplinary PhD research in a developing country context, focusing on three individual PhD case studies in South Africa. Design/Methodology/Approach: Multiple-case method was used, and three completed transdisciplinary PhD research efforts undertaken at the Stellenbosch…

  15. 40 CFR 401.17 - pH Effluent limitations under continuous monitoring.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 28 2010-07-01 2010-07-01 true pH Effluent limitations under... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS GENERAL PROVISIONS § 401.17 pH Effluent limitations under continuous monitoring. (a) Where a permittee continuously measures the pH of wastewater pursuant to...

  16. 40 CFR 434.62 - Alternate effluent limitation for pH.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Alternate effluent limitation for pH... PERFORMANCE STANDARDS Miscellaneous Provisions § 434.62 Alternate effluent limitation for pH. Where the... otherwise applicable manganese limitations, the permit issuer may allow the pH level in the final...

  17. 40 CFR 432.3 - General limitation or standard for pH.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false General limitation or standard for pH... standard for pH. Any discharge subject to BPT, BCT, or NSPS limitations or standards in this part must remain within the pH range of 6 to 9....

  18. Developing Discourses of Knowledge and Understanding: Longitudinal Studies of Ph.D. Supervision

    ERIC Educational Resources Information Center

    Kandiko, Camille B.; Kinchin, Ian M.

    2013-01-01

    Competing notions of what a Ph.D. has been, is and should be are undercurrents in doctoral education. A longitudinal study of Ph.D. supervision based on interviews and concept mapping was used to surface understandings of the purpose of a Ph.D. This research tracks change over time for both the student and the supervisor. The data were analysed…

  19. Regulation of neuronal connexin-36 channels by pH.

    PubMed

    González-Nieto, Daniel; Gómez-Hernández, Juan M; Larrosa, Belén; Gutiérrez, Cristina; Muñoz, María D; Fasciani, Ilaria; O'Brien, John; Zappalà, Agata; Cicirata, Federico; Barrio, Luis C

    2008-11-04

    Neurotransmission through electrical synapses plays an important role in the spike synchrony among neurons and oscillation of neuronal networks. Indeed, electrical transmission has been implicated in the hypersynchronous electrical activity of epilepsy. We have investigated the influence of intracellular pH on the strength of electrical coupling mediated by connexin36 (Cx36), the principal gap junction protein in the electrical synapses of vertebrates. In striking contrast to other connexin isoforms, the activity of Cx36 channels decreases following alkalosis rather than acidosis when it is expressed in Xenopus oocytes and N2A cells. This uncoupling of Cx36 channels upon alkalinization occurred in the vertebrate orthologues analyzed (human, mouse, chicken, perch, and skate). While intracellular acidification caused a mild or moderate increase in the junctional conductance of virtually all these channels, the coupling of the skate Cx35 channel was partially blocked by acidosis. The mutational analysis suggests that the Cx36 channels may contain two gating mechanisms operating with opposing sensitivity to pH. One gate, the dominant mechanism, closes for alkalosis and it probably involves an interaction between the C- and N-terminal domains, while a secondary acid sensing gate only causes minor, albeit saturating, changes in coupling following acidosis and alkalosis. Thus, we conclude that neuronal Cx36 channels undergo unique regulation by pH(i) since their activity is inhibited by alkalosis rather than acidosis. These data provide a novel basis to define the relevance and consequences of the pH-dependent modulation of Cx36 synapses under physiological and pathological conditions.

  20. Functional genomics of pH homeostasis in Corynebacterium glutamicum revealed novel links between pH response, oxidative stress, iron homeostasis and methionine synthesis

    PubMed Central

    2009-01-01

    Background The maintenance of internal pH in bacterial cells is challenged by natural stress conditions, during host infection or in biotechnological production processes. Comprehensive transcriptomic and proteomic analyses has been conducted in several bacterial model systems, yet questions remain as to the mechanisms of pH homeostasis. Results Here we present the comprehensive analysis of pH homeostasis in C. glutamicum, a bacterium of industrial importance. At pH values between 6 and 9 effective maintenance of the internal pH at 7.5 ± 0.5 pH units was found. By DNA microarray analyses differential mRNA patterns were identified. The expression profiles were validated and extended by 1D-LC-ESI-MS/MS based quantification of soluble and membrane proteins. Regulators involved were identified and thereby participation of numerous signaling modules in pH response was found. The functional analysis revealed for the first time the occurrence of oxidative stress in C. glutamicum cells at neutral and low pH conditions accompanied by activation of the iron starvation response. Intracellular metabolite pool analysis unraveled inhibition of the TCA and other pathways at low pH. Methionine and cysteine synthesis were found to be activated via the McbR regulator, cysteine accumulation was observed and addition of cysteine was shown to be toxic under acidic conditions. Conclusions Novel limitations for C. glutamicum at non-optimal pH values were identified by a comprehensive analysis on the level of the transcriptome, proteome, and metabolome indicating a functional link between pH acclimatization, oxidative stress, iron homeostasis, and metabolic alterations. The results offer new insights into bacterial stress physiology and new starting points for bacterial strain design or pathogen defense. PMID:20025733

  1. The Influence of pH on Prokaryotic Cell Size and Temperature

    NASA Astrophysics Data System (ADS)

    Sundararajan, D.; Gutierrez, F.; Heim, N. A.; Payne, J.

    2015-12-01

    The pH of a habitat is essential to an organism's growth and success in its environment. Although most organisms maintain a neutral internal pH, their environmental pH can vary greatly. However, little research has been done concerning an organism's environmental pH across a wide range of taxa. We studied pH tolerance in prokaryotes and its relationship with biovolume, taxonomic classification, and ideal temperature. We had three hypotheses: pH and temperature are not correlated; pH tolerance is similar within taxonomic groups; and extremophiles have small cell sizes. To test these hypotheses, we used pH, size, and taxonomic data from The Prokaryotes. We found that the mean optimum external pH was neutral for prokaryotes as a whole and when divided by domain, phylum, and class. Using ANOVA to test for pH within and among group variances, we found that variation of pH in domains, phyla, classes, and families was greater than between them. pH and size did not show much of a correlation, except that the largest and smallest sized prokaryotes had nearly neutral pH. This seems significant because extremophiles need to divert more of their energy from growth to maintain a neutral internal pH. Acidophiles showed a larger range of optimum pH values than alkaliphiles. A similar result was seen with the minimum and maximum pH values of acidophiles and alkaliphiles. While acidophiles were spread out and had some alkaline maximum values, alkaliphiles had smaller ranges, and unlike some acidophiles that had pH minimums close to zero, alkaliphile pH maximums did not go beyond a pH of 12. No statistically significant differences were found between sizes of acidophiles and alkaliphiles. However, optimum temperatures of acidophiles and alkaliphiles did have a statistically significant difference. pH and temperature had a negative correlation. Therefore, pH seems to have a correlation with cell size, temperature, and taxonomy to some extent.

  2. EMS provider determinations of necessity for transport and reimbursement for EMS response, medical care, and transport: combined resource document for the National Association of EMS Physicians position statements.

    PubMed

    Millin, Michael G; Brown, Lawrence H; Schwartz, Brian

    2011-01-01

    With increasing demands for emergency medical services (EMS), many EMS jurisdictions are utilizing EMS provider-initiated nontransport policies as a method to offload potentially nonemergent patients from the EMS system. EMS provider determination of medical necessity, resulting in nontransport of patients, has the potential to avert unnecessary emergency department visits. However, EMS systems that utilize these policies must have additional education for the providers, a quality improvement process, and active physician oversight. In addition, EMS provider determination of nontransport for a specific situation should be supported by evidence in the peer-reviewed literature that the practice is safe. Further, EMS systems that do not utilize these programs should not be financially penalized. Payment for EMS services should be based on the prudent layperson standard. EMS systems that do utilize nontransport policies should be appropriately reimbursed, as this represents potential cost savings to the health care system.

  3. School Budget Hold'em Facilitator's Guide

    ERIC Educational Resources Information Center

    Education Resource Strategies, 2012

    2012-01-01

    "School Budget Hold'em" is a game designed to help school districts rethink their budgeting process. It evolved out of Education Resource Strategies' (ERS) experience working with large urban districts around the country. "School Budget Hold'em" offers a completely new approach--one that can turn the budgeting process into a long-term visioning…

  4. Rodent models of pulmonary hypertension: harmonisation with the world health organisation's categorisation of human PH.

    PubMed

    Ryan, J; Bloch, K; Archer, S L

    2011-08-01

    The WHO classification of pulmonary hypertension (PH) recognises five distinct groups, all sharing a mean, resting, pulmonary artery pressure (PAP) > 25 mmHg. The aetiology of PH varies by group (1-pulmonary vascular disease, 2-high left heart filling pressures, 3-hypoxia, 4-unresolved pulmonary embolism and 5-miscellaneous). Inclusion in a group reflects shared histological, haemodynamic and pathophysiological features and has therapeutic implications. Advantages of using rodent models to understand the pathophysiology of human PH and to test experimental therapies include the economy, safety and mechanistic certainty they provide. As rodent models are meant to reflect human PH, they should be categorised by a parallel PH classification and limitations in achieving this ideal recognised. Challenges with rodent models include: accurate phenotypic characterisation (haemodynamics, histology and imaging), species and strain variations in the natural history of PH, and poor fidelity to the relevant human PH group. Rat models of group 1 PH include: monocrotaline (± pneumonectomy), chronic hypoxia + SU-5416 (a VEGF receptor inhibitor) and the fawn-hooded rat (FHR). Mouse models of group 1 PH include: transgenic mice overexpressing the serotonin transporter or dominant-negative mutants of bone morphogenetic protein receptor-2. Group 1 PH is also created by infecting S100A4/Mts1 mice with γ-herpesvirus. The histological features of group 1 PH, but not PH itself, are induced by exposure to Schistosoma mansoni or Stachybotrys chartarum. Group 3 PH is modelled by exposure of rats or mice to chronic hypoxia. Rodent models of groups 2, 4 and 5 PH are needed. Comprehensive haemodynamic, histological and molecular phenotyping, coupled with categorisation into WHO PH groups, enhances the utility of rodent models.

  5. Effect of environmental pH on enzyme activity and growth of Bacteroides gingivalis W50.

    PubMed Central

    McDermid, A S; McKee, A S; Marsh, P D

    1988-01-01

    Since the pH of the gingival crevice increases from below neutrality in health to above pH 8 in disease, we decided to investigate the effect of environmental pH on the growth and enzyme activity of Bacteroides gingivalis W50. Cells were grown in a chemostat under hemin-excess conditions over a range of pH values; stable growth was observed only between pH 6.7 and 8.3, with the maximum yields obtained between pH 7.0 and 8.0. The enzyme profile of cells varied markedly with pH. Enzymes with a specificity for gingival connective tissue (collagenase, hyaluronidase) were produced optimally at or below neutral pH, whereas trypsinlike activity increased with the growth pH and was maximal at pH 8.0. Chymotrypsinlike activity was generally low, although its activity was highest at the extremes of growth pH, i.e., at pH 6.7 and 8.3. Inhibitor studies provided evidence that the breakdown of collagen involved the concerted action of both a collagenase and the trypsinlike enzyme. The ratio of trypsin to collagenolytic activity rose from 1:1 during growth at neutral pH and below to almost 7:1 during growth at pH 8.3. Thus B. gingivalis appears to be uniquely adapted as a periodontopathic organism in that under environmental conditions likely to prevail during the initial stages of pocket development it produces maximally those enzymes with a tissue-damaging potential. Then, as the pH of the pocket rises during the host inflammatory response, the activity of the trypsinlike enzyme increases markedly, which may enable cells to inactivate key components of the host defenses such as immunoglobulins and complement. PMID:3281900

  6. The pH of beverages available to the American consumer

    PubMed Central

    Reddy, Avanija; Norris, Don F.; Momeni, Stephanie S.; Waldo, Belinda; Ruby, John D.

    2015-01-01

    Background Dental erosion (DE) is the chemical dissolution of tooth structure in the absence of bacteria when the environment is acidic (pH < 4.0). Recent studies indicate that low pH is the primary determinant of beverage erosive potential although citrate chelation of calcium ions may contribute to erosion at higher pH. The purpose of this study was to determine the erosive potential measured by the pH of commercially available beverages. Methods A total of 380 beverages were purchased from stores in Birmingham, Alabama, categorized (e.g. juices, sodas) and assessed for pH. An Accumet AR 15 pH meter was used to measure the pH of each beverage in triplicate immediately after opening at 25°C. The pH data were recorded as mean ± standard deviation. Results The majority (93%, 355/380) of beverages had a pH below 4.0 and 7% (25/380) had a pH ≥4. Relative beverage erosivity zones based on previous studies of apatite solubility in acid indicated: 39% (150/380) of the beverages were considered extremely erosive (pH <3.0); 54% (205/380) were considered erosive (pH 3.0 to 3.99); 7% (25/380) were considered minimally erosive (pH ≥4.0). Conclusions This comprehensive pH assessment of beverages available for human consumption found that the majority are potentially erosive to the dentition. This study will provide dental clinicians and hygienists information regarding the erosive potential (pH) of commercially available beverages. Practical Implications Specific dietary recommendations for the prevention of dental erosion may now be developed based on the patient’s history of beverage consumption. PMID:26653863

  7. Ratiometric imaging of extracellular pH in bacterial biofilms with C-SNARF-4.

    PubMed

    Schlafer, Sebastian; Garcia, Javier E; Greve, Matilde; Raarup, Merete K; Nyvad, Bente; Dige, Irene

    2015-02-01

    pH in the extracellular matrix of bacterial biofilms is of central importance for microbial metabolism. Biofilms possess a complex three-dimensional architecture characterized by chemically different microenvironments in close proximity. For decades, pH measurements in biofilms have been limited to monitoring bulk pH with electrodes. Although pH microelectrodes with a better spatial resolution have been developed, they do not permit the monitoring of horizontal pH gradients in biofilms in real time. Quantitative fluorescence microscopy can overcome these problems, but none of the hitherto employed methods differentiated accurately between extracellular and intracellular microbial pH and visualized extracellular pH in all areas of the biofilms. Here, we developed a method to reliably monitor extracellular biofilm pH microscopically with the ratiometric pH-sensitive dye C-SNARF-4, choosing dental biofilms as an example. Fluorescent emissions of C-SNARF-4 can be used to calculate extracellular pH irrespective of the dye concentration. We showed that at pH values of <6, C-SNARF-4 stained 15 bacterial species frequently isolated from dental biofilm and visualized the entire bacterial biomass in in vivo-grown dental biofilms with unknown species composition. We then employed digital image analysis to remove the bacterial biomass from the microscopic images and adequately calculate extracellular pH values. As a proof of concept, we monitored the extracellular pH drop in in vivo-grown dental biofilms fermenting glucose. The combination of pH ratiometry with C-SNARF-4 and digital image analysis allows the accurate monitoring of extracellular pH in bacterial biofilms in three dimensions in real time and represents a significant improvement to previously employed methods of biofilm pH measurement.

  8. Finite element analysis of time-independent superconductivity. Ph.D. Thesis Final Report

    NASA Technical Reports Server (NTRS)

    Schuler, James J.

    1993-01-01

    The development of electromagnetic (EM) finite elements based upon a generalized four-potential variational principle is presented. The use of the four-potential variational principle allows for downstream coupling of EM fields with the thermal, mechanical, and quantum effects exhibited by superconducting materials. The use of variational methods to model an EM system allows for a greater range of applications than just the superconducting problem. The four-potential variational principle can be used to solve a broader range of EM problems than any of the currently available formulations. It also reduces the number of independent variables from six to four while easily dealing with conductor/insulator interfaces. This methodology was applied to a range of EM field problems. Results from all these problems predict EM quantities exceptionally well and are consistent with the expected physical behavior.

  9. MONITORING THE SPECIATION OF AQUEOUS FREE CHLORINE FROM PH 1-12 WITH RAMAN SPECTROSCOPY TO DETERMINE THE IDENTITY OF THE POTENT LOW-PH OXIDANT

    EPA Science Inventory

    The speciation of aqueous free chlorine above pH 5 is a well-understood equilibrium of H2O + HOCl (equilibrium) OCl- + H3O+ with a pKa of 7.5. However, the identity of another very potent oxidant present at low pH (below 5) has been attributed by some researchers to Cl2 (aq), a...

  10. Effects of pH and Carbon Source on Synechococcus PCC 7002 Cultivation: Biomass and Carbohydrate Production with Different Strategies for pH Control.

    PubMed

    De Farias Silva, Carlos Eduardo; Sforza, Eleonora; Bertucco, Alberto

    2017-02-01

    Synechococcus PCC 7002 is an interesting species in view of industrial production of carbohydrates. The cultivation performances of this species are strongly affected by the pH of the medium, which also influences the carbohydrate accumulation. In this work, different methods of pH control were analyzed, in order to obtain a higher production of both Synechococcus biomass and carbohydrates. To better understand the influence of pH on growth and carbohydrate productivity, manual and automatic pH regulation in CO2 and bicarbonate system were applied. The pH value of 8.5 resulted the best to achieve both of these goals. From an industrial point of view, an alternative way to maintain the pH practically constant during the entire period of cultivation is the exploitation of the bicarbonate-CO2 buffer system, with the double aim to maintain the pH in the viability range and also to provide the amount of carbon required by growth. In this condition, a high concentration of biomass (6 g L(-1)) and carbohydrate content (around 60 %) were obtained, which are promising in view of a potential use for bioethanol production. The chemical equilibrium of C-N-P species was also evaluated by applying the ionic balance equations, and a relation between the sodium bicarbonate added in the medium and the equilibrium value of pH was discussed.

  11. Side mounted EMS for aluminium scrap melters

    SciTech Connect

    Eidem, M.; Tallbaeck, G.; Hanley, P.J.

    1996-10-01

    Normally the electromagnetic stirrer (EMS) is placed below the furnace. However it has recently been found that the EMS can also be placed at the side of the furnace, still giving good stirring. This makes it possible to install EMS on most existing furnaces. The side-mounted EMS is compared with the standard bottom-mounted stirrer with respect to installation, melting time and flow pattern in the melt. The major conclusion is that a side-mounted EMS is practical and will give about as good a performance as the bottom-mounted. Melting time estimates are based upon 3-D fluid flow and heat transfer predictions in combination with a simplified scrap melting theory. Predicted melting times are in fair agreement with operational data for mechanically stirred and electromagnetically bottom stirred furnaces.

  12. The Al(I) molecule, Ph2COAl and its anion

    NASA Astrophysics Data System (ADS)

    Zhang, Xinxing; Eichhorn, Bryan; Schnöckel, Hansgeorg; Bowen, Kit

    2016-08-01

    We have formed the Al(I)-containing molecule, benzophenone-aluminum, i.e., Ph2COAl, and studied it by conducting density functional theory calculations on both its neutral and anionic forms and by measuring the photoelectron spectrum of its anion. Our calculations identified two nearly iso-energetic anion isomers, (Ph2COAl)-, the vertical detachment energies (VDE) of which are in excellent agreement with our photoelectron spectrum. Natural population analysis (NPA) of Ph2COAl found the Al moiety to be positively charged by +0.81 e, indicating a strongly ionic bond between Al and Ph2CO, i.e., Ph2CO-Al+.

  13. Regulation of Intracellular pH in Lungs and Other Tissues During Hypercapnia

    DTIC Science & Technology

    1978-03-10

    was observed in terms of "percent pH regula- sumed to equal venous Pco 2. tion." As shown in Fig. 1, the pH of kidney, lung, and Intracellular pH was...buffering. The value, "percent pH 80 Z70regulation" (19), calculated as (Alog HCO3/log Pco 2) - x 100 is also used to quantitate pH regulation. This...42: 2080-2093, 1964. 6. FENN, W. 0. Carbon dioxide and intracellular homeostasis . 19. SCHAEFER, K. E., M. HASSON, AND H. NIEMOELLER. Effect of Ann. NY

  14. Fluorescence of anthocyanin pigments in plant extracts at various pH

    NASA Astrophysics Data System (ADS)

    Pliszka, Barbara; Olszewska, Teresa; Drabent, Regina

    2001-07-01

    The fluorescence properties of anthocyanin pigments in extracts of red cabbage, Brassica oleracea, have been studied. The fluorescence spectra and fluorescence excitation spectra have been measured with absorption spectra of anthocyanins in extracts at pH 2 and pH 7. The results of the researches show that kinds of fluorescent anthocyanins (or/and other compounds) depend on pH conditions of red cabbage extracts. The properly chosen parameters of fluorescence measurement allow to distinguish spectrally two different fluorescent anthocyanin compounds in extract at pH 2 in comparison to pH 7, where three fluorescent compounds have been found.

  15. Molecular Components of the Neurospora crassa pH Signaling Pathway and Their Regulation by pH and the PAC-3 Transcription Factor

    PubMed Central

    Virgilio, Stela; Cupertino, Fernanda Barbosa; Bernardes, Natália Elisa; Freitas, Fernanda Zanolli; Takeda, Agnes Alessandra Sekijima; Fontes, Marcos Roberto de Mattos; Bertolini, Maria Célia

    2016-01-01

    Environmental pH induces a stress response triggering a signaling pathway whose components have been identified and characterized in several fungi. Neurospora crassa shares all six components of the Aspergillus nidulans pH signaling pathway, and we investigate here their regulation during an alkaline pH stress response. We show that the N. crassa pal mutant strains, with the exception of Δpal-9, which is the A. nidulans palI homolog, exhibit low conidiation and are unable to grow at alkaline pH. Moreover, they accumulate the pigment melanin, most likely via regulation of the tyrosinase gene by the pH signaling components. The PAC-3 transcription factor binds to the tyrosinase promoter and negatively regulates its gene expression. PAC-3 also binds to all pal gene promoters, regulating their expression at normal growth pH and/or alkaline pH, which indicates a feedback regulation of PAC-3 in the pal gene expression. In addition, PAC-3 binds to the pac-3 promoter only at alkaline pH, most likely influencing the pac-3 expression at this pH suggesting that the activation of PAC-3 in N. crassa results from proteolytic processing and gene expression regulation by the pH signaling components. In N. crassa, PAC-3 is proteolytically processed in a single cleavage step predominately at alkaline pH; however, low levels of the processed protein can be observed at normal growth pH. We also demonstrate that PAC-3 preferentially localizes in the nucleus at alkaline pH stress and that the translocation may require the N. crassa importin-α since the PAC-3 nuclear localization signal (NLS) has a strong in vitro affinity with importin-α. The data presented here show that the pH signaling pathway in N. crassa shares all the components with the A. nidulans and S. cerevisiae pathways; however, it exhibits some properties not previously described in either organism. PMID:27557053

  16. Molecular Components of the Neurospora crassa pH Signaling Pathway and Their Regulation by pH and the PAC-3 Transcription Factor.

    PubMed

    Virgilio, Stela; Cupertino, Fernanda Barbosa; Bernardes, Natália Elisa; Freitas, Fernanda Zanolli; Takeda, Agnes Alessandra Sekijima; Fontes, Marcos Roberto de Mattos; Bertolini, Maria Célia

    2016-01-01

    Environmental pH induces a stress response triggering a signaling pathway whose components have been identified and characterized in several fungi. Neurospora crassa shares all six components of the Aspergillus nidulans pH signaling pathway, and we investigate here their regulation during an alkaline pH stress response. We show that the N. crassa pal mutant strains, with the exception of Δpal-9, which is the A. nidulans palI homolog, exhibit low conidiation and are unable to grow at alkaline pH. Moreover, they accumulate the pigment melanin, most likely via regulation of the tyrosinase gene by the pH signaling components. The PAC-3 transcription factor binds to the tyrosinase promoter and negatively regulates its gene expression. PAC-3 also binds to all pal gene promoters, regulating their expression at normal growth pH and/or alkaline pH, which indicates a feedback regulation of PAC-3 in the pal gene expression. In addition, PAC-3 binds to the pac-3 promoter only at alkaline pH, most likely influencing the pac-3 expression at this pH suggesting that the activation of PAC-3 in N. crassa results from proteolytic processing and gene expression regulation by the pH signaling components. In N. crassa, PAC-3 is proteolytically processed in a single cleavage step predominately at alkaline pH; however, low levels of the processed protein can be observed at normal growth pH. We also demonstrate that PAC-3 preferentially localizes in the nucleus at alkaline pH stress and that the translocation may require the N. crassa importin-α since the PAC-3 nuclear localization signal (NLS) has a strong in vitro affinity with importin-α. The data presented here show that the pH signaling pathway in N. crassa shares all the components with the A. nidulans and S. cerevisiae pathways; however, it exhibits some properties not previously described in either organism.

  17. Micro Electrochemical pH Sensor Applicable for Real-Time Ratiometric Monitoring of pH Values in Rat Brains.

    PubMed

    Zhou, Jie; Zhang, Limin; Tian, Yang

    2016-02-16

    To develop in vivo monitoring meter for pH measurements is still the bottleneck for understanding the role of pH plays in the brain diseases. In this work, a selective and sensitive electrochemical pH meter was developed for real-time ratiometric monitoring of pH in different regions of rat brains upon ischemia. First, 1,2-naphthoquinone (1,2-NQ) was employed and optimized as a selective pH recognition element to establish a 2H(+)/2e(-) approach over a wide range of pH from 5.8 to 8.0. The pH meter demonstrated remarkable selectivity toward pH detection against metal ions, amino acids, reactive oxygen species, and other biological species in the brain. Meanwhile, an inner reference, 6-(ferrocenyl)hexanethiol (FcHT), was selected as a built-in correction to avoid the environmental effect through coimmobilization with 1,2-NQ. In addition, three-dimensional gold nanoleaves were electrodeposited onto the electrode surface to amplify the signal by ∼4.0-fold and the measurement was achieved down to 0.07 pH. Finally, combined with the microelectrode technique, the microelectrochemical pH meter was directly implanted into brain regions including the striatum, hippocampus, and cortex and successfully applied in real-time monitoring of pH values in these regions of brain followed by global cerebral ischemia. The results demonstrated that pH values were estimated to 7.21 ± 0.05, 7.13 ± 0.09, and 7.27 ± 0.06 in the striatum, hippocampus, and cortex in the rat brains, respectively, in normal conditions. However, pH decreased to 6.75 ± 0.07 and 6.52 ± 0.03 in the striatum and hippocampus, upon global cerebral ischemia, while a negligible pH change was obtained in the cortex.

  18. Mercury and other element exposure in tree swallows nesting at low pH and neutral pH lakes in northern Wisconsin USA

    USGS Publications Warehouse

    Custer, Thomas W.; Custer, Christine M.; Thogmartin, Wayne E.; Dummer, Paul M.; Rossmann, Ronald; Kenow, Kevin P.; Meyer, Michael W.

    2012-01-01

    The primary objective of this study was to determine whether tree swallows (Tachycineta bicolor) demonstrate similar responses to lake pH and mercury (Hg) contamination in northern Wisconsin as do common loons (Gavia immer). Similar to common loons, Hg concentrations in the blood of tree swallow nestlings were higher, Hg concentrations in eggs tended to be higher, and egg size tended to be smaller at low (<6.2) pH lakes. In contrast to common loons, tree swallow nestling production was not lower at low pH lakes. Based on modeling associations, Hg concentrations in tree swallow eggs and nestling blood can be used to predict Hg concentrations in common loons without the invasive or destructive sampling of loons. Mean concentrations of cadmium, manganese, and mercury in nestling livers were higher at low pH lakes than neutral pH lakes. Concentrations of cadmium, chromium, mercury, selenium, and zinc were not at toxic levels.

  19. Effect of initial solution pH on photo-induced reductive decomposition of perfluorooctanoic acid.

    PubMed

    Qu, Yan; Zhang, Chao-Jie; Chen, Pei; Zhou, Qi; Zhang, Wei-Xian

    2014-07-01

    The effects of initial solution pH on the decomposition of perfluorooctanoic acid (PFOA) with hydrated electrons as reductant were investigated. The reductive decomposition of PFOA depends strongly on the solution pH. In the pH range of 5.0-10.0, the decomposition and defluorination rates of PFOA increased with the increase of the initial solution pH. The rate constant was 0.0295 min(-1) at pH 10.0, which was more than 49.0 times higher than that at pH 5.0. Higher pH also inhibits the generation of toxic intermediates during the PFOA decomposition. For example, the short-chain PFCAs reached a lower maximum concentration in shorter reaction time as pH increasing. The peak areas of accumulated fluorinated and iodinated hydrocarbons detected by GC/MS under acidic conditions were nearly 10-100 times more than those under alkaline conditions. In short, alkaline conditions were more favorable for photo-induced reduction of PFOA as high pH promoted the decomposition of PFOA and inhibited the accumulation of intermediate products. The concentration of hydrated electron, detected by laser flash photolysis, increased with the increase of the initial pH. This was the main reason why the decomposition of PFOA in the UV-KI system depended strongly on the initial pH.

  20. Influence of pH on heat resistance of Bacillus licheniformis in buffer and homogenised foods.

    PubMed

    Palop, A; Raso, J; Pagán, R; Condón, S; Sala, F J

    1996-02-01

    The influence of pH of heating menstruum (McIlvaine buffer) on the heat resistance of Bacillus licheniformis was investigated and compared with the heat resistance in homogenised tomato and asparagus at pH 7 and 4 in a wide range of temperatures. Heat resistance was in all mestrua smaller at acid pH. At 99 degrees C and pH 4, heat resistance was 1/20 lower than at pH 7. However, the magnitude of this effect decreased as heat treatment temperatures were increased almost disappearing at 120 degrees C. z values increased from 6.85 at pH 7, to 10.75 at pH 4. At 99 degrees C the effect of pH on heat resistance was constant along the range of pH's tested. The increase of one pH unit increased D99 by 180%. At pH 7 and 4, heat resistance was the same in buffer as in tomato and asparagus homogenates at all temperatures tested. The diminishing influence of the acidification of some foods on the heat resistance of B. licheniformis sterilisation temperatures should be taken into account when a raise in temperature is considered to shorten the duration of heat processes.

  1. Evidence that pH can drive state transitions in isolated thylakoid membranes from spinach.

    PubMed

    Singh-Rawal, Pooja; Jajoo, Anjana; Mathur, Sonal; Mehta, Pooja; Bharti, Sudhakar

    2010-06-01

    Our observation that the F735/F685 ratio at 77 K increased when the lumenal pH decreased led us to investigate the role of pH in explaining the mechanism of state transitions in spinach (Spinacea oleracea L.) thylakoid membranes. As the lumenal pH was changed from pH 7.5 to 5.5, the quantum yield of PS II decreased, while that of PS I increased. In the presence of an uncoupler, NH(4)Cl, which sequesters protons, a reversal of the effects observed at pH 5.5 were noticed. The thylakoid membranes treated with NaF at pH 5.5, when suspended in a buffer of pH 7.5, showed enhanced PS II fluorescence and a decreased PS I fluorescence, suggesting migration of LHC II back to PS II from PS I. The results presented here suggest for the first time that the lumenal pH of thylakoid membranes regulates the migration of antenna, and hence the energy distribution, between the two photosystems, i.e. a low lumenal pH (pH 5.5) favors antenna migration from PS II to PS I. At pH 7.5, the deprotonation of LHC II antenna attached to PS I leads to back migration of LHC II to PS II.

  2. Muscle surface pH: measurement technique and responses to acidosis and alkalosis.

    PubMed

    Kost, G J

    1982-01-01

    The technique of muscle surface pH measurement used clinically was refined for application in animal experimentation. Guidelines for electrode utilization were developed, and sources of error were investigated. In pentobarbital sodium-anesthetized rabbits, during steady-state conditions, the surface pH of the medial gastrocnemius [7.39 +/- 0.05 (SD)] was equal to that of the soleus, and both were lower than femoral venous outflow pH (7.42 +/- 0.04, P less than 0.001), which was lower than arterial pH (7.46 +/- 0.05, P less than 0.001). With acid-base infusions, the same relationship found during steady-state control conditions (arterial greater than venous outflow greater than muscle surface pH) was observed despite large fluctuations in blood pH. Only during forced hypoventilation, when CO2 transiently moved into muscle, did the relationship reverse. In all experiments, muscle surface pH followed venous outflow pH more closely than it followed arterial pH, the soleus more rapidly than the medial gastrocnemius. Results were consistent with the physiological characteristics of the two muscles and demonstrated that muscle surface pH reflects the local pH of the interstitial compartment under the site of electrode placement.

  3. Note: In vivo pH imaging system using luminescent indicator and color camera

    NASA Astrophysics Data System (ADS)

    Sakaue, Hirotaka; Dan, Risako; Shimizu, Megumi; Kazama, Haruko

    2012-07-01

    Microscopic in vivo pH imaging system is developed that can capture the luminescent- and color-imaging. The former gives a quantitative measurement of a pH distribution in vivo. The latter captures the structural information that can be overlaid to the pH distribution for correlating the structure of a specimen and its pH distribution. By using a digital color camera, a luminescent image as well as a color image is obtained. The system uses HPTS (8-hydroxypyrene-1,3,6-trisulfonate) as a luminescent pH indicator for the luminescent imaging. Filter units are mounted in the microscope, which extract two luminescent images for using the excitation-ratio method. A ratio of the two images is converted to a pH distribution through a priori pH calibration. An application of the system to epidermal cells of Lactuca Sativa L is shown.

  4. The Skap-hom dimerization and PH domains comprise a 3'-phosphoinositide-gated molecular switch.

    PubMed

    Swanson, Kenneth D; Tang, Yong; Ceccarelli, Derek F; Poy, Florence; Sliwa, Jan P; Neel, Benjamin G; Eck, Michael J

    2008-11-21

    PH domains, by binding to phosphoinositides, often serve as membrane-targeting modules. Using crystallographic, biochemical, and cell biological approaches, we have uncovered a mechanism that the integrin-signaling adaptor Skap-hom uses to mediate cytoskeletal interactions. Skap-hom is a homodimer containing an N-terminal four-helix bundle dimerization domain, against which its two PH domains pack in a conformation incompatible with phosphoinositide binding. The isolated PH domains bind PI[3,4,5]P(3), and mutations targeting the dimerization domain or the PH domain's PI[3,4,5]P(3)-binding pocket prevent Skap-hom localization to ruffles. Targeting is retained when the PH domain is deleted or by combined mutation of the PI[3,4,5]P(3)-binding pocket and the PH/dimerization domain interface. Thus, the dimerization and PH domain form a PI[3,4,5]P(3)-responsive molecular switch that controls Skap-hom function.

  5. Low pH effects on swimming activity of Ambystoma salamander larvae

    SciTech Connect

    Kutka, F.J. . Dept. of Animal Ecology)

    1994-11-01

    Swimming activity of larval Ambystoma laterale increased linearly with pH between pH 4.0 and 6.5; near inactivity occurred at pH 4.0. Ambystoma maculatum exhibited a weaker relationship between activity and pH, and overall was less active than A. laterale. However, survival of larval A. maculatum declined linearly with pH in the presence of adult diving beetles (Dytiscus verticalis), with significantly lower survival below pH 4.8. These results suggest that, as with embryos, salamander larvae may suffer from pH levels below 5.0, even though these levels are not directly lethal. Because of their sensitivity, ease, and short duration, activity tests are recommended with amphibian larvae for use in other risk assessments.

  6. Soil redox and pH effects on methane production in a flooded rice soil

    SciTech Connect

    Wang, Z.P.; DeLaune, R.D.; Masscheleyn, P.H.; Patrick, W.H.

    1993-01-01

    Methane formation in soil is a microbiological process controlled by many factors. Of them soil redox potential (Eh) and soil pH are considered as critical controls. A laboratory incubation experiment was conducted to study the critical initiation soil Eh, the optimum soil pH, and the interaction of Eh and pH on methane production. A small decrease in pH resulting from the introduction of acidic materials significantly decreased methane production. However, a slight increase in soil pH (about 0.2 unit higher than the natural soil suspension pH) resulted in an enhancement of methane production by 11-20 percent and 24-25 percent at controlled Eh of -250 mV and -200 mV, respectively. Results suggest that decrease in methane emission could be obtained by a small reduction in soil pH in Crowley soil.

  7. Strategy for pH control and pH feedback-controlled substrate feeding for high-level production of L-tryptophan by Escherichia coli.

    PubMed

    Cheng, Li-Kun; Wang, Jian; Xu, Qing-Yang; Zhao, Chun-Guang; Shen, Zhi-Qiang; Xie, Xi-Xian; Chen, Ning

    2013-05-01

    Optimum production of L-tryptophan by Escherichia coli depends on pH. Here, we established conditions for optimizing the production of L-tryptophan. The optimum pH range was 6.5-7.2, and pH was controlled using a three-stage strategy [pH 6.5 (0-12 h), pH 6.8 (12-24 h), and pH 7.2 (24-38 h)]. Specifically, ammonium hydroxide was used to adjust pH during the initial 24 h, and potassium hydroxide and ammonium hydroxide (1:2, v/v) were used to adjust pH during 24-38 h. Under these conditions, NH4 (+) and K(+) concentrations were kept below the threshold for inhibiting L-tryptophan production. Optimization was also accomplished using ratios (v/v) of glucose to alkali solutions equal to 4:1 (5-24 h) and 6:1 (24-38 h). The concentration of glucose and the pH were controlled by adjusting the pH automatically. Applying a pH-feedback feeding method, the steady-state concentration of glucose was maintained at approximately 0.2 ± 0.02 g/l, and acetic acid accumulated to a concentration of 1.15 ± 0.03 g/l, and the plasmid stability was 98 ± 0.5 %. The final, optimized concentration of L-tryptophan was 43.65 ± 0.29 g/l from 52.43 ± 0.38 g/l dry cell weight.

  8. Improved volatile fatty acids anaerobic production from waste activated sludge by pH regulation: Alkaline or neutral pH?

    PubMed

    Ma, Huijun; Chen, Xingchun; Liu, He; Liu, Hongbo; Fu, Bo

    2016-02-01

    In this study, the anaerobic fermentation was carried out for volatile fatty acids (VFAs) production at different pH (between 7.0 and 10.0) conditions with untreated sludge and heat-alkaline pretreated waste activated sludge. In the fermentation with untreated sludge, the extent of hydrolysis of organic matters and extent of acidification at alkaline pH are 54.37% and 30.37%, respectively, resulting in the highest VFAs yield at 235.46mg COD/gVS of three pH conditions. In the fermentation with heat-alkaline pretreated sludge, the acidification rate and VFAs yield at neutral pH are 30.98% and 240.14mg COD/gVS, respectively, which are higher than that at other pH conditions. With the glucose or bovine serum albumin as substrate for VFAs production, the neutral pH showed a higher VFAs concentration than the alkaline pH condition. The results of terminal restriction fragment length polymorphism (T-RFLP) analysis indicated that the alkaline pH caused low microbial richness. Based on the results in this study, we demonstrated that the alkaline pH is favor of hydrolysis of organic matter in sludge while neutral pH improved the acidogenesis for the VFAs production from sludge. Our finding is obvious different to the previous research and helpful for the understanding of how heat-alkaline pretreatment and alkaline fermentation influence the VFAs production, and beneficial to the development of VFAs production process.

  9. Soil bacterial and fungal communities across a pH gradient in an arable soil.

    PubMed

    Rousk, Johannes; Bååth, Erland; Brookes, Philip C; Lauber, Christian L; Lozupone, Catherine; Caporaso, J Gregory; Knight, Rob; Fierer, Noah

    2010-10-01

    Soils collected across a long-term liming experiment (pH 4.0-8.3), in which variation in factors other than pH have been minimized, were used to investigate the direct influence of pH on the abundance and composition of the two major soil microbial taxa, fungi and bacteria. We hypothesized that bacterial communities would be more strongly influenced by pH than fungal communities. To determine the relative abundance of bacteria and fungi, we used quantitative PCR (qPCR), and to analyze the composition and diversity of the bacterial and fungal communities, we used a bar-coded pyrosequencing technique. Both the relative abundance and diversity of bacteria were positively related to pH, the latter nearly doubling between pH 4 and 8. In contrast, the relative abundance of fungi was unaffected by pH and fungal diversity was only weakly related with pH. The composition of the bacterial communities was closely defined by soil pH; there was as much variability in bacterial community composition across the 180-m distance of this liming experiment as across soils collected from a wide range of biomes in North and South America, emphasizing the dominance of pH in structuring bacterial communities. The apparent direct influence of pH on bacterial community composition is probably due to the narrow pH ranges for optimal growth of bacteria. Fungal community composition was less strongly affected by pH, which is consistent with pure culture studies, demonstrating that fungi generally exhibit wider pH ranges for optimal growth.

  10. Effects of different pH conditions on enamel erosion repair by nano fluorapatite pastes.

    PubMed

    Wang, Chengjie; Zhang, Yifei; Wei, Jie; Wei, Shicheng

    2012-09-01

    The effects of different pH conditions on enamel erosion repair by nano fluorapatite (n-FA) pastes were evaluated in this study. Eighteen human dental enamel blocks with artificially-induced erosion were randomly divided into three groups that were coated with n-FA pastes with 3 different pH values (pH < 1, pH = 4.5 and pH = 7.5, respectively) for 15 minutes. SEM, XRD, XPS, Vickers microhardness test and mass measurement were performed for the enamels before and after treatment. A layer of enamel-like fluoride substituted hydroxyapatite was observed on the surface of all the samples. After treatment by n-FA pastes with 3 different pH values (pH < 1, pH = 4.5 and pH = 7.5), the Vickers micro-hardness value was respectively changed to 125.9 HV, 252.1 HV and 304.9 HV from 241.3 HV of the artificial enamel erosion, and mass loss was 0.75 mg/mm2, 0.41 mg/mm2 and 0.30 mg/mm2, respectively. SEM analysis showed that the surface of the enamels treated by n-FA pastes with pH 7.5 and pH 4.5 was smoother than those treated by n-FA pastes with pH < 1. These results suggested that the pH value had significant effects for the repairment of enamel erosion with n-FA pastes. This study demonstrated that the n-FA paste with neutral pH value (7.5) for enamel erosion repair would not only significantly enhance the enamel surface hardness, but also avoid the enamel mass loss and increased surface roughness.

  11. Acidic pH of the lateral intercellular spaces of MDCK cells cultured on permeable supports.

    PubMed

    Chatton, J Y; Spring, K R

    1994-06-01

    The pH of the lateral intercellular space (LIS) of Madin-Darby canine kidney (MDCK) cell monolayers grown on permeable supports was investigated by microspectrofluorimetry using BCECF (2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein). The permeability of the support was selectively reduced by growing Zn-Al-silicate crystals inside its pores. The diffusion of BCECF across the filter was sufficiently retarded to allow measurements of fluorescence in the LIS. The LIS pH and intracellular pH of the cells surrounding them were determined in HEPES-buffered solutions. When the perfusate pH was 7.4, the LIS pH was more acidic (7.06 +/- 0.02) and equaled the cytoplasmic pH (7.08 +/- 0.05). When perfusate was changed to pH 7.0 or 7.8, the LIS changed linearly by about half the magnitude of the perfusate pH. Intracellular pH followed LIS pH variations between perfusate pH 7.0 and 7.4 but was significantly higher when perfusate pH was 7.8. Tight junctional H+ permeability was undetectably low. The low steady-state pH in the LIS was not altered by inhibitors of acid transport or low temperature. Rapid perturbations of pH in the LIS showed that protons were not immobilized in the LIS. The acidic microenvironment within the LIS may be the result of buffering by the cell surface proteins.

  12. pH transients during salt removal in isoelectric trapping separations: a curse revisited.

    PubMed

    Shave, Evan; Vigh, Gyula

    2007-02-01

    The pH transients that occur during isoelectric trapping separations as a result of the removal of nonampholytic ionic components have been re-examined. Salts containing strong electrolyte anions and cations, both with equal and dissimilar mobilities, have been studied using anodic and cathodic buffering membranes whose pH values were both equidistant and nonequidistant from pH 7. The direction and magnitude of the pH transient (acidic or basic) was found to depend on both the mobilities of the anion and cation (mu(anion)/mu(cation)) and the pH difference between pH 7 and the pH of the buffering membranes (|pH(memb) (anodic) - 7|/|7 - pH(memb) (cathodic)|). When |pH(memb) (anodic) - 7|/|7 - pH(memb) (cathodic)| = 1, mu(anion)/mu(cation)<1 leads to an acidic pH transient, mu(anion)/mu(cation) = 1 eliminates the pH transient and mu(anion)/mu(cation)>1 leads to a basic pH transient. When mu(anion)/mu(cation) = 1, |pH(memb) (anodic) - 7|/|7 - pH(memb) (cathodic)|<1 leads to a basic pH transient, |pH(memb) (anodic) - 7|/|7 - pH(memb) (cathodic)| = 1 eliminates the pH transient and |pH(memb) (anodic) - 7|/|7 - pH(memb) (cathodic)|>1 leads to an acidic pH transient. By selecting appropriate anodic and cathodic buffering membranes to adjust the |pH(memb) (anodic) - 7|/|7 - pH(memb) (cathodic)| value, pH transients caused by dissimilar anion and cation mobilities can be avoided.

  13. Evaluation of pH of Bathing Soaps and Shampoos for Skin and Hair Care

    PubMed Central

    Tarun, Jose; Susan, Jose; Suria, Jacob; Susan, Veronica John; Criton, Sebastian

    2014-01-01

    Background: Normal healthy skin has potential of hydrogen (pH) range of 5.4-5.9 and a normal bacterial flora. Use of soap with high pH causes an increase in skin pH, which in turn causes an increase in dehydrative effect, irritability and alteration in bacterial flora. The majority of soaps and shampoos available in the market do not disclose their pH. Aims and Objectives: The aim of this study was to assess the pH of different brands of bathing soaps and shampoos available in the market. Materials and Methods: The samples of soaps and shampoos were collected from shops in the locality. The samples of different brands are coded before the analysis of the pH. Solution of each sample was made and pH was measured using pH meter. Results: Majority of the soaps have a pH within the range of 9-10. Majority of the shampoos have a pH within the range of 6-7. Conclusions: The soaps and shampoos commonly used by the population at large have a pH outside the range of normal skin and hair pH values. Therefore, it is hoped that before recommending soap to patient especially those who have sensitive and acne prone skin, due consideration is given to the pH factor and also that manufacturers will give a thought to pH of soaps and shampoos manufactured by them, so that their products will be more skin and hair friendly. PMID:25284846

  14. The effect of pH on chronic aquatic nickel toxicity is dependent on the pH itself: Extending the chronic nickel bioavailability models.

    PubMed

    Nys, Charlotte; Janssen, Colin R; Van Sprang, Patrick; De Schamphelaere, Karel A C

    2016-05-01

    The environmental quality standard for Ni in the European Commission's Water Framework Directive is bioavailability based. Although some of the available chronic Ni bioavailability models are validated only for pH ≤ 8.2, a considerable fraction of European surface waters has a pH > 8.2. Therefore, the authors investigated the effect of a change in pH from 8.2 to 8.7 on chronic Ni toxicity in 3 invertebrate (Daphnia magna, Lymnaea stagnalis, and Brachionus calyciflorus) and 2 plant species (Pseudokirchneriella subcapitata and Lemna minor). Nickel toxicity was almost always significantly higher at pH 8.7 than at pH 8.2. To test whether the existing chronic Ni bioavailability models developed for pH ≤ 8.2 can be used at higher pH levels, Ni toxicity at pH 8.7 was predicted based on Ni toxicity observed at pH 8.2. This resulted in a consistent underestimation of toxicity. The results suggest that the effect of pH on Ni(2+) toxicity is dependent on the pH itself: the slope of the pH effect is steeper above than below pH 8.2 for species for which a species-specific bioavailability model exists. Therefore, the existing chronic Ni bioavailability models were modified to allow predictions of chronic Ni toxicity to invertebrates and plants in the pH range of 8.2 to 8.7 by applying a pH slope (SpH ) dependent on the pH of the target water. These modified Ni bioavailability models resulted in more accurate predictions of Ni toxicity to all 5 species (within 2-fold error), without the bias observed using the bioavailability models developed for pH ≤ 8.2. The results of the present study can decrease the uncertainty in implementing the bioavailability-based environmental quality standard under the Water Framework Directive for high-pH regions in Europe.

  15. Mitochondrial nitric oxide synthase regulates mitochondrial matrix pH.

    PubMed

    Ghafourifar, P; Richter, C

    1999-01-01

    Nitric oxide (nitrogen monoxide, NO) exerts a wide profile of its biological activities via regulation of respiration and respiration-dependent functions. The presence of nitric oxide synthase (NOS) in mitochondria (mtNOS) was recently reported by us (Ghafourifar and Richter, FEBS Lett. 418, 291-296, 1997) and others (Giulivi et al., J. Biol. Chem. 273, 11038-11043, 1998). Here we report that NO, provided by an NO donor as well as by mtNOS stimulation, regulates mitochondrial matrix pH, transmembrane potential and Ca2+ buffering capacity. Exogenously-added NO causes a dose-dependent matrix acidification. Also mtNOS stimulation, induced by loading mitochondria with Ca2+, causes mitochondrial matrix acidification and a drop in mitochondrial transmembrane potential. Inhibition of mtNOS's basal activity causes mitochondrial matrix alkalinization and provides a resistance to the sudden drop of mitochondrial transmembrane potential induced by mitochondrial Ca2+ uptake. We conclude that mtNOS plays a critical role in regulating mitochondrial delta(pH).

  16. Ventilatory regulation of arterial H(+) (pH) during exercise.

    PubMed

    Wasserman, Karlman; Cox, Timothy A; Sietsema, Kathy E

    2014-01-01

    We hypothesized that exercise ventilation and arterial H(+) ([H(+)]a) are mutually interactive, [H(+)]a stimulating V(E) and V(E) regulating [H(+)]a increase. Fifty-five patients were studied, 10 normal and 45 with cardio-respiratory disorders. Each patient underwent cardiopulmonary exercise testing with simultaneous serial arterial blood gas and pH measurements. Subsequently, they were classified into one of 7 clinical groups: (1) normal, (2) exercise-induced hypoxemia (PaO2<50mmHg), (3) exercise-induced myocardial ischemia, (4) heart failure, (5) COPD, (6) interstitial lung disease, and (7) pulmonary vasculopathy. The average resting pHa was 7.42 or 7.43 for each group. At anaerobic (lactic acidosis) threshold (AT), [H(+)]a increased due to PaCO2 increase (+2mmHg), primarily. At peak exercise, [H(+)]a increased further due to arterial HCO3(-) decrease. In summary, [H(+)]a appears to be closely regulated at rest to AT and further to peak exercise by CO2 elimination from the venous return. No evidence was observed for over-ventilation of CO2, causing the arterial blood to become more alkaline during exercise in the patient groups studied.

  17. PH-dependent forms of red wine anthocyanins as antioxidants.

    PubMed

    Lapidot, T; Harel, S; Akiri, B; Granit, R; Kanner, J

    1999-01-01

    Anthocyanins are one of the main classes of flavonoids in red wines, and they appear to contribute significantly to the powerful antioxidant properties of the flavonoids. In grapes and wines the anthocyanins are in the flavylium form. However, during digestion they may reach higher pH values, forming the carbinol pseudo-base, quinoidal-base, or the chalcone, and these compounds appear to be absorbed from the gut into the blood system. The antioxidant activity of these compounds, in several metal-catalyzed lipid oxidation model systems, was evaluated in comparison with other antioxidants. The pseudo-base and quinoidal-base malvidin 3-glucoside significantly inhibited the peroxidation of linoleate by myoglobin. Both compounds were found to work better than catechin, a well-known antioxidant. In a membrane lipid peroxidation system, the effectiveness of the antioxidant was dependent on the catalyst: In the presence of H(2)O(2)-activated myoglobin, the inhibition efficiency of the antioxidant was malvidin 3-glucoside > catechin > malvidin > resveratrol. However, in the presence of an iron redox cycle catalyzer, the order of effectiveness was resveratrol > malvidin 3-glucoside = malvidin > catechin. The pH-transformed forms of the anthocyanins remained effective antioxidants in these systems, and their I(50) values were between 0.5 and 6.2 microM.

  18. Astrobites: The Astro-ph Reader's Digest For Undergraduates

    NASA Astrophysics Data System (ADS)

    Newton, Elisabeth R.; Kohler, S.; Gifford, D.; Plunkett, A. L.; Astrobites Team

    2012-01-01

    Astrobites (http://astrobites.com) is a daily blog aimed primarily at undergraduates interested in astrophysical research and written by a team of graduate students from around the country. Every day we present a journal article recently posted to astro-ph in a brief format that is accessible to anyone with a general background in the physical sciences. In addition to summarizing new work, Astrobites provides valuable context for readers not yet familiar with the astrophysical literature. Special posts offer career guidance for undergraduates (e.g. applying for an NSF graduate fellowship) and describe personal experiences (e.g. attending an astronomy summer school). We will discuss the Astrobites format, readership statistics and the results of our October reader survey (117 responses). The Astrobites blog is currently receiving 17000 on-site hits per month with an average of 600 all-time views per post. 17% of our readers are undergraduate students and 34% are graduates, while researchers and astronomy enthusiasts make up the remainder in equal parts. Out of the 60 students surveyed, 75% plan on a career in research in astrophysics. EN and DG acknowledge support from the National Science Foundation through Graduate Research Fellowships.

  19. Gaseous hydrogen embrittlement of PH 13-8 Mo steel

    NASA Astrophysics Data System (ADS)

    Ding, Y. S.; Tsay, L. W.; Chiang, M. F.; Chen, C.

    2009-04-01

    In this study, notched tensile and fatigue crack growth tests in gaseous hydrogen were performed on PH 13-8 Mo stainless steel specimens at room temperature. These specimens were susceptible to hydrogen embrittlement (HE), but at different degrees, depending on the aging conditions or the microstructures of the alloys. In hydrogen, the accelerated fatigue crack growth rate (FCGR) usually accompanied a reduced notched tensile strength (NTS) of the specimens, i.e., the faster the FCGR the lower the NTS. It was proposed that the same fracture mechanism could be applied to these two different types of specimens, regardless of the loading conditions. Rapid fatigue crack growth and high NTS loss were found in the H800 (426 °C under-aged) and H900 (482 °C peak-aged) specimens. The HE susceptibility of the steel was reduced by increasing the aging temperature above 593 °C, which was attributed to the increased amount of austenite in the structure. Extensive quasi-cleavage fracture was observed for the specimens that were deteriorated severely by HE.

  20. EM International, July 1994, Volume 2

    SciTech Connect

    Not Available

    1994-10-01

    The Office of Environmental Management (EM) at the Department of Energy (DOE) is seeking out and leveraging foreign technology, data, and resources in keeping with EM`s mandate to protect public health and the environment through the safe and cost-effective remediation of the Department`s nuclear weapons sites. EM works closely with foreign governments, industry, and universities to obtain innovative environmental technologies, scientific and engineering expertise, and operations experience that will support EM`s objectives. Where appropriate, these international resources are used to manage the more urgent risks at our sites, secure a safe workplace, help build consensus on critical issues, and strengthen our technology development program. Through international agreements EM engages in cooperative exchange of information, technology, and individuals. Currently, we are managing agreements with a dozen countries in Europe, Latin America, and Asia. These agreements focus on environmental restoration, waste management, transportation of radioactive wastes, and decontamination and decommissioning. This publication contains the following articles: in situ remediation integrated program; in-situ characterization and inspection of tanks; multimedia environmental pollutant assessment system (MEPAS); LLNL wet oxidation -- AEA technology. Besides these articles, this publication covers: EU activities with Russia; technology transfer activities; and international organization activities.

  1. Distribution of the genus Cyclotella in relation to pH in Precambrian Shield lakes: implications for diatom-inferred pH

    SciTech Connect

    Taylor, M.C.; Duthie, H.C.; Smith, S.M.

    1987-12-01

    Recent research on relationships between diatoms and pH suggest that the genus Cyclotella exhibits a strong relationship with lake acidity, being almost totally absent below pH 5.5. This decline has been used as an indicator of lake acidification in paleolimnological studies. In this study C. stelligera V.H. and C. kuetzingiana Thwaites were abundant in Precambrian Sheild lakes with pH as low as 4.5. Cyclotella comta (Ehr.) Kuetz. was found in lakes of pH <5.5, but maximum abundance was observed in lakes of pH >5.5. Cyclotella michiganiana Skv. was found in lakes of pH >6.0. These results indicate that the use of C. stelligera, C. kuetzingiana, and possibly C. comta, in paleolimnological investigations of lake acidification, should be approached with caution. These taxa may exhibit a decline in abundance with decreasing lake water pH, but this is partially a morphometric effect not necessarily related to anthropogenic acidification.

  2. Acidification of the North Pacific Ocean: Direct Observations of pH in 1991 and 2006

    NASA Astrophysics Data System (ADS)

    Byrne, R. H.; Liu, X.; Mecking, S.; Feely, R. A.

    2006-12-01

    Spectrophotometric procedures were first successfully used to obtain seawater pH profiles on a 1991 cruise within the CLIVAR/CO2 Repeat Hydrography Program. During a 2006 reoccupation of the P16N transect along 152 ^{0}W, closely similar methods were used to obtain a fifteen-year spectrophotometrically-based record of ocean pH change. Spectrophotometric procedures are particularly robust as a means of observing changes in seawater pH because sulfonephthalein equilibrium constants, being nearly constant at constant temperature and salinity, are unimportant in pH difference calculations. In such cases, the quality of pH difference measurements is most closely related to measurement precision. Since the precision of spectrophotometric pH measurements (using observations of sulfonephthalein absorbance ratios) is on the order of 0.0004 pH units, pH differences can be measured with a precision somewhat better than +/- 0.001. In the absence of other effects, the atmospheric pCO2 increase between 1991 and 2006 would decrease the pH of the surface ocean, in equilibrium with the atmosphere, by approximately 0.025 pH units. Thus, spectrophotometric pH observations are capable of directly resolving pH perturbations on a scale commensurate with potential atmospherically-induced changes. At depths between 3000 and 5000 meters the directly observed mean fifteen-year pH difference was on the order of 0.000 +/-0.0015. At depths below 1000 meters, pH changes generally ranged between + 0.006 and -0.006. In contrast, in the upper 700 meters, pH was much more variable, with an average fifteen-year pH decrease on the order of 0.025 and including pH differences as large as -0.055. These directly observed pH differences are consistent with expected changes in response to elevated atmospheric CO2, along with changes that can be attributed to differences in respiration and changes in ocean circulation.

  3. Project X RFQ EM Design

    SciTech Connect

    Romanov, Gennady; Hoff, Matthew; Li, Derun; Staples, John; Virostek, Steve; /LBNL

    2012-05-09

    Project X is a proposed multi-MW proton facility at Fermi National Accelerator Laboratory (FNAL). The Project X front-end would consist of an H- ion source, a low-energy beam transport (LEBT), a CW 162.5 MHz radio-frequency quadrupole (RFQ) accelerator, and a medium-energy beam transport (MEBT). Lawrence Berkeley National Laboratory (LBNL) and FNAL collaboration is currently developing the designs for various components in the Project X front end. This paper reports the detailed EM design of the CW 162.5 MHz RFQ that provides bunching of the 1-10 mA H- beam with acceleration from 30 keV to 2.1 MeV.

  4. Carbon dioxide addition to microbial fuel cell cathodes maintains sustainable catholyte pH and improves anolyte pH, alkalinity, and conductivity.

    PubMed

    Fornero, Jeffrey J; Rosenbaum, Miriam; Cotta, Michael A; Angenent, Largus T

    2010-04-01

    Bioelectrochemical system (BES) pH imbalances develop due to anodic proton-generating oxidation reactions and cathodic hydroxide-ion-generating reduction reactions. Until now, workers added unsustainable buffers to reduce the pH difference between the anode and cathode because the pH imbalance contributes to BES potential losses and, therefore, power losses. Here, we report that adding carbon dioxide (CO(2)) gas to the cathode, which creates a CO(2)/bicarbonate buffered catholyte system, can diminish microbial fuel cell (MFC) pH imbalances in contrast to the CO(2)/carbonate buffered catholyte system by Torres, Lee, and Rittmann [Environ. Sci. Technol. 2008, 42, 8773]. We operated an air-cathode and liquid-cathode MFC side-by-side. For the air-cathode MFC, CO(2) addition resulted in a stable catholyte film pH of 6.61 +/- 0.12 and a 152% increase in steady-state power density. By adding CO(2) to the liquid-cathode system, we sustained a steady catholyte pH (pH = 5.94 +/- 0.02) and a low pH imbalance (DeltapH = 0.65 +/- 0.18) over a 2-week period without external salt buffer addition. By migrating bicarbonate ions from the cathode to the anode (with an anion-exchange membrane), we increased the anolyte pH (DeltapH = 0.39 +/- 0.31), total alkalinity (494 +/- 6 to 582 +/- 6 as mg CaCO(3)/L), and conductivity (1.53 +/- 0.49 to 2.16 +/- 0.03 mS/cm) relative to the feed properties. We also verified with a phosphate-buffered MFC that our reaction rates were limited mainly by the reactor configuration rather than limitations due to the bicarbonate buffer.

  5. Modeling of salt and pH gradient elution in ion-exchange chromatography.

    PubMed

    Schmidt, Michael; Hafner, Mathias; Frech, Christian

    2014-01-01

    The separation of proteins by internally and externally generated pH gradients in chromatofocusing on ion-exchange columns is a well-established analytical method with a large number of applications. In this work, a stoichiometric displacement model was used to describe the retention behavior of lysozyme on SP Sepharose FF and a monoclonal antibody on Fractogel SO3 (S) in linear salt and pH gradient elution. The pH dependence of the binding charge B in the linear gradient elution model is introduced using a protein net charge model, while the pH dependence of the equilibrium constant is based on a thermodynamic approach. The model parameter and pH dependences are calculated from linear salt gradient elutions at different pH values as well as from linear pH gradient elutions at different fixed salt concentrations. The application of the model for the well-characterized protein lysozyme resulted in almost identical model parameters based on either linear salt or pH gradient elution data. For the antibody, only the approach based on linear pH gradients is feasible because of the limited pH range useful for salt gradient elution. The application of the model for the separation of an acid variant of the antibody from the major monomeric form is discussed.

  6. Continuous intra-arterial blood pH monitoring in rabbits with acid-base disorders.

    PubMed

    Jin, Weizhong; Jiang, Jinjun; Wang, Xun; Zhu, Xiaodan; Wang, Guifang; Song, Yuanlin; Bai, Chunxue

    2011-07-31

    The acid-base balance of arterial blood is important for the clinical management of seriously ill patients, especially patients with acute lung injury or acute respiratory distress syndrome. We developed a novel fluorosensor for continuous blood pH monitoring and evaluated its performance both in vitro and in vivo in rabbits with acid-base disorders. The pH sensor is made of N-allyl-4-piperazinyl-1, 8-napthalimide and 2-hydroxyethyl methacrylate, which were bonded at the distal end of the optical fiber. The fluorescence intensity increased as the pH decreased with good reproducibility, selectivity and linearity in the pH range of 6-8. The pH measurement precision was 0.03 ± 0.03 pH units with a bias of -0.02 ± 0.04 (n = 105) and -0.00 ± 0.05 pH units (n=189) in rabbits with metabolic and respiratory acid-base orders, respectively. The optical pH sensor can accurately measure pH fluctuations with a fast response and is a promising candidate for continuous in-line measurements of blood pH in critical care patients.

  7. Intracellular pH responses in the industrially important fungus Trichoderma reesei.

    PubMed

    Valkonen, Mari; Penttilä, Merja; Benčina, Mojca

    2014-09-01

    Preserving an optimal intracellular pH is critical for cell fitness and productivity. The pH homeostasis of the industrially important filamentous fungus Trichoderma reesei (Hypocrea jecorina) is largely unexplored. We analyzed the impact of growth conditions on regulation of intracellular pH of the strain Rut-C30 and the strain M106 derived from the Rut-C30 that accumulates L-galactonic acid-from provided galacturonic acid-as a consequence of L-galactonate dehydratase deletion. For live-cell measurements of intracellular pH, we used the genetically encoded ratiometric pH-sensitive fluorescent protein RaVC. Glucose and lactose, used as carbon sources, had specific effects on intracellular pH of T. reesei. The growth in lactose-containing medium extensively acidified cytosol, while intracellular pH of hyphae cultured in a medium with glucose remained at a higher level. The strain M106 maintained higher intracellular pH in the presence of D-galacturonic acid than its parental strain Rut-C30. Acidic external pH caused significant acidification of cytosol. Altogether, the pH homeostasis of T. reesei Rut-C30 strain is sensitive to extracellular pH and the degree of acidification depends on carbon source.

  8. Insulin Fibrillization at Acidic and Physiological pH Values is Controlled by Different Molecular Mechanisms.

    PubMed

    Noormägi, Andra; Valmsen, Karin; Tõugu, Vello; Palumaa, Peep

    2015-12-01

    Formation of amyloid-like fibrils by insulin was studied at different insulin concentrations, pH and temperatures. At low pH (pH 2.5) the insulin fibrillization occurred only at high ([10 lM) peptide concentrations, whereas at physiological pH values the fibril formation is inhibited at higher insulin concentrations. The enthalpy of activation Ea of the fibril growth at pH 2.5 equals to 33 kJ/mol, which is considerably lower than 84 kJ/mol at physiological pH. The fibrillization rate of insulin decreases with increasing pH at high, 250 lM concentration, which was opposite to the pH effect observed in 2.5 lM insulin solutions. The latter effect indicates that protonation of histidine residues seems to be important for the fibrillization of monomeric insulin, whereas the pH effect at high concentration may result from off-pathway oligomerization propensity. Together, the different effect of environmental factors on the insulin fibrillization suggest that the reaction rate is controlled by different molecular events in acidic conditions and at physiological pH values.

  9. Relation of pH to toxicity of lampricide TFM in the laboratory

    USGS Publications Warehouse

    Bills, T.D.; Marking, L.L.; Howe, G.E.; Rach, J.J.

    1988-01-01

    In the control of larval sea lamprey (Petromyzon marinus ) with 3-trifluoromethyl-4-nitrophenol (TFM) in tributaries of the Great Lakes, occasional kills of other fishes have caused concern about the effects of the chemical on non-target organisms. Stream treatment rates have been based on previous application rates, alkalinity measurements, results of on-site toxicity tests, or combinations of these. Laboratory studies in 1987 showed that pH is the primary factor that affects the toxicity of TFM (the lower the pH, the greater the toxicity): even small changes in pH alter the toxicity, whereas substantial changes in alkalinity have little effect. In 12-h exposures, the 96-h LC50 for TFM to rainbow trout (Salmo gairdneri ) ranged from about 0.9 mg/L at pH 6.5 to > 100 mg/L at pH 9.5, but (at pH 7.5) the LC50's differed little at total alkalinities of about 18 mg/L and 207 mg/L. Decreases in pH as small as 0.5 pH unit caused nontoxic solutions to become toxic to rainbow trout. Some kills of non-target fish during stream treatments were reportedly caused by decreases in pH, and (conversely) that some stream treatments for sea lampreys were ineffective because pH increased.

  10. High-resolution ocean pH dynamics in four subtropical Atlantic benthic habitats

    NASA Astrophysics Data System (ADS)

    Hernández, C. A.; Clemente, S.; Sangil, C.; Hernández, J. C.

    2015-12-01

    Oscillations of ocean pH are largely unknown in coastal environments and ocean acidification studies often do not account for natural variability yet most of what is known about marine species and populations is found out via studies conducted in near shore environments. Most experiments designed to make predictions about future climate change scenarios are carried out in coastal environments with no research that takes into account the natural pH variability. In order to fill this knowledge gap and to provide reliable measures of pH oscillation, seawater pH was measured over time using moored pH sensors in four contrasting phytocenoses typical of the north Atlantic subtropical region. Each phytocenosis was characterized by its predominant engineer species: (1) Cystoseira abies-marina, (2) a mix of gelidiales and geniculate corallines, (3) Lobophora variegata, and (4) encrusting corallines. The autonomous pH measuring systems consisted of a pH sensor; a data logger and a battery encased in a waterproof container and allowed the acquisition of high-resolution continuous pH data at each of the study sites. The pH variation observed ranged by between 0.09 and 0.24 pHNBS units. A clear daily variation in seawater pH was detected at all the studied sites (0.04-0.12 pHNBS units). Significant differences in daily pH oscillations were also observed between phytocenoses, which shows that macroalgal communities influence the seawater pH in benthic habitats. Natural oscillations in pH must be taken into account in future ocean acidification studies to put findings in perspective and for any ecological recommendations to be realistic.

  11. Use of human amelogenin in molecular encapsulation for the design of pH responsive microparticles

    PubMed Central

    2012-01-01

    Background Proteins can be used in drug delivery systems to improve pharmacological properties of an active substance. Differences in pH between tissues can be utilized in order to achieve a targeted drug release at a specific location or tissue, such as a tumor. The enamel matrix protein amelogenin has a pH dependent solubility profile and self-assemble to form aggregates at neutral pH. This could make amelogenin useful in the design of pH responsive drug delivery systems. Results In this study amelogenin was evaluated as a pH responsive component in drug delivery applications. This was achieved by testing the ability of amelogenin to entrap/release other proteins upon changes in pH, and by testing if amelogenin could confer pH responsiveness to an existing and versatile drug delivery system, such as gelatin microparticles. Amelogenin was able to encapsulate bovine serum albumin and insulin, whichwere used as model target proteins. The composite aggregates of amelogenin and target protein were formed at neutral pH and could be reversibly solubilized at weakly acidic pH. Gelatin microparticles prepared in the presence of amelogenin, showed a modulated structure in response to pH change, when studied by scanning electron microscopy, compared to particles without amelogenin. At neutral pH amelogenin induced formation of pores in the particle surface, which were not present at acidic pH, or in particles lacking amelogenin. Conclusions The results from this study demonstrate that amelogenin can be a useful component in drug delivery systems in order to achieve a pH dependent response. PMID:22630169

  12. Molecular Basis of pH and Ca2+ Regulation of Aquaporin Water Permeability

    PubMed Central

    Németh-Cahalan, Karin L.; Kalman, Katalin; Hall, James E.

    2004-01-01

    Aquaporins facilitate the diffusion of water across cell membranes. We previously showed that acid pH or low Ca2+ increase the water permeability of bovine AQP0 expressed in Xenopus oocytes. We now show that external histidines in loops A and C mediate the pH dependence. Furthermore, the position of histidines in different members of the aquaporin family can “tune” the pH sensitivity toward alkaline or acid pH ranges. In bovine AQP0, replacement of His40 in loop A by Cys, while keeping His122 in loop C, shifted the pH sensitivity from acid to alkaline. In the killifish AQP0 homologue, MIPfun, with His at position 39 in loop A, alkaline rather than acid pH increased water permeability. Moving His39 to His40 in MIPfun, to mimic bovine AQP0 loop A, shifted the pH sensitivity back to the acid range. pH regulation was also found in two other members of the aquaporin family. Alkaline pH increased the water permeability of AQP4 that contains His at position 129 in loop C. Acid and alkaline pH sensitivity was induced in AQP1 by adding histidines 48 (in loop A) and 130 (in loop C). We conclude that external histidines in loops A and C that span the outer vestibule contribute to pH sensitivity. In addition, we show that when AQP0 (bovine or killifish) and a crippled calmodulin mutant were coexpressed, Ca2+ sensitivity was lost but pH sensitivity was maintained. These results demonstrate that Ca2+ and pH modulation are separable and arise from processes on opposite sides of the membrane. PMID:15078916

  13. Active transport, ion movements, and pH changes : I. The chemistry of pH changes.

    PubMed

    Good, N E

    1988-10-01

    The transport of substances across cell membranes may be the most fundamental activity of living things. When the substance transported is any ion there can be a change in the concentration of hydrogen ions on the two sides of the membrane. These hydrogen ion concentration changes are not caused by fluxes of hydrogen ions although fluxes of hydrogen ions may sometimes be involved. The reason for the apparent contradiction is quite simple. All aqueous systems are subject to two constraints: (1) to maintain the charge balance, the sum of the cationic charges must equal the sum of the anionic charges and (2) the product of the molar concentration of H(+) and the molar concentration of OH(-), established and maintained by the association and the dissociation of water, remains always at 10(-14). As a consequence the concentrations of H(+) and OH(-) are determined uniquely by differences between the concentrations of the other cations and anions, with [H(+)] and [OH(-)] being dependent variables. Hydrogen ions and hydroxyl ions can be produced or consumed in local reactions whereas any strong ions such as Cl(-), Mg(2+), or K(+) can be neither produced nor consumed in biological reactions. Further consequences of these truisms are outlined here in terms of the chemistry of the kinds of reactions which can lead to pH changes.

  14. [Phosphatase activity in Amoeba proteus at low pH].

    PubMed

    Sopina, V A

    2009-01-01

    In free-living Amoeba proteus (strain B), three forms of tartrate-sensitive phosphatase were revealed using PAGE of the supernatant of ameba homogenates obtained with 1% Triton X-100 or distilled water and subsequent staining of gels with 2-naphthyl phosphate as substrate (pH 4.0). The form with the highest mobility in the ameba supernatant was sensitive to all tested phosphatase activity modulators. Two other forms with the lower mobilities were completely or significantly inactivated not only by sodium L-(+)-tartrate, but also by L-(+)-tartaric acid, sodium orthovanadate, ammonium molybdate, EDTA, EGTA, o-phospho-L-tyrosine, DL-dithiotreitol, H2O2, 2-mercaptoethanol, and ions of heavy metals - Fe2+, Fe3+, and Cu2+. Based on results of inhibitory analysis, lysosome location in the ameba cell, and wide substrate specificity of these two forms, it has been concluded that they belong to nonspecific acid phosphomonoesterases (AcP, EC 3.1.3.2). This AcP is suggested to have both phosphomonoesterase and phosphotyrosyl-protein phosphatase activitis. Two ecto-phosphatases were revealed in the culture medium, in which amebas were cultivated. One of them was inhibited by the same reagents as the ameba tartrate-sensitive AcP and seems to be the AcP released into the culture medium in the process of exocytosis of the content of food vacuoles. In the culture medium, apart from this AcP, another phosphatase was revealed, which was not inhibited by any tested inhibitors of AcP and alkaline phosphatase. It cannot be ruled out that this phosphatase belong to the ecto-ATPases found in many protists; however, its ability to hydrolyze ATP has not yet been proven.

  15. Growth of water hyacinth in municipal landfill leachate with different pH.

    PubMed

    El-Gendy, A S; Biswas, N; Bewtra, J K

    2004-07-01

    Batch experiments were conducted to investigate the effect of municipal landfill leachate pH on the growth of water hyacinth (Eichhornia crassipes). These experiments were carried out in a green house environment on leachate samples collected from Essex-Windsor Regional Landfill, Windsor, Ontario, Canada. It was found that water hyacinth plants survived in a pH range of 4.0 to 8.0. Both alkaline pH (above 8.0) and highly acidic pH (below 4.0) had inhibitory effect on the growth of plants. The pH range, for optimum growth of the water hyacinth plants was found to be 5.8 to 6.0. At optimum growth, water hyacinth had an average mean relative growth rate of 0.043 d-1. It was found that nitrogen compounds underwent different transformations depending on the pH of leachate. Plant uptake, nitrification and volatilization were among these transformations.

  16. Analysis of individual versus group behavior of zebrafish: a model using pH sublethal effects.

    PubMed

    Magalhães, Danielly de Paiva; Buss, Daniel Forsin; da Cunha, Rodolfo Armando; Linde-Arias, Ana Rosa; Baptista, Darcilio Fernandes

    2012-06-01

    An image analysis biomonitoring system was used to evaluate sublethal effects of pH on the mean swimming velocity of zebrafish. Responses to stress were tested comparing individual and group responses. Group analysis indicated no effect for all acid pH and for pH 9.0-9.5. Individual analysis indicated behavioral differences for most acid pH and higher than 9.5. Sensitivity to sublethal pH was best assessed when using individual analysis. Zebrafish decreased hyperactivity and increased hypoactivity with more acid or alkaline pH. Individual approach allowed to determine hyperactivity or hypoactivity and the species' thresholds of exposure, which is critical for the management of impairments.

  17. What Took Them So Long? Explaining PhD Delays among Doctoral Candidates

    PubMed Central

    van de Schoot, Rens; Yerkes, Mara A.; Mouw, Jolien M.; Sonneveld, Hans

    2013-01-01

    A delay in PhD completion, while likely undesirable for PhD candidates, can also be detrimental to universities if and when PhD delay leads to attrition/termination. Termination of the PhD trajectory can lead to individual stress, a loss of valuable time and resources invested in the candidate and can also mean a loss of competitive advantage. Using data from two studies of doctoral candidates in the Netherlands, we take a closer look at PhD duration and delay in doctoral completion. Specifically, we address the question: Is it possible to predict which PhD candidates will experience delays in the completion of their doctorate degree? If so, it might be possible to take steps to shorten or even prevent delay, thereby helping to enhance university competitiveness. Moreover, we discuss practical do's and don'ts for universities and graduate schools to minimize delays. PMID:23935895

  18. Role of pH in metal adsorption from aqueous solutions containing chelating agents on chitosan

    SciTech Connect

    Wu, F.C.; Tseng, R.L.; Juang, R.S.

    1999-01-01

    The role of pH in adsorption of Cu(II) from aqueous solutions containing chelating agents on chitosan was emphasized. Four chelating agents including ethylenediaminetetraacetic acid (EDTA), citric acid, tartaric acid, and sodium gluconate were used. It was shown that the adsorption ability of Cu(II) on chitosan from its chelated solutions varied significantly with pH variations. The competition between coordination of Cu(II) with unprotonated chitosan and electrostatic interaction of the Cu(II) chelates with protonated chitosan took place because of the change in solution pH during adsorption. The maximum adsorption capacity was obtained within each optimal pH range determined from titration curves of the chelated solutions. Coordination of Cu(II) with the unprotonated chitosan was found to dominate at pH below such an optimal pH value.

  19. Yogurt made from milk heated at different pH values.

    PubMed

    Ozcan, Tulay; Horne, David S; Lucey, John A

    2015-10-01

    Milk for yogurt manufacture is subjected to high heat treatment to denature whey proteins. Low milk pH values (≤ 6.5) at heating result in most denatured whey proteins becoming associated with casein micelles, whereas high milk pH values (≥ 7.0) at heating result in the formation of mostly soluble (nonmicellar) denatured whey protein complexes. There are conflicting reports on the relative importance of soluble and casein-bound whey protein aggregates on the properties of acid gels. Prior studies investigating the effect of pH of milk at heating used model gels in which milk was acidified by glucono-δ-lactone; in this study, we prepared yogurt gels using commercial starter cultures. Model acid gels can have very different texture and physical properties from those made by fermentation with starter cultures. In this study, we investigated the effects of different pH values of milk at heating on the rheological, light backscatter, and microstructural properties of yogurt gels. Reconstituted skim milk was adjusted to pH values 6.2, 6.7, and 7.2 and heated at 85°C for 30 min. A portion of the heated milk samples was readjusted back to pH 6.7 after heating. Milks were inoculated with 3% (wt/wt) yogurt starter culture and incubated at 40°C until pH 4.6. Gel formation was monitored using dynamic oscillatory rheology, and parameters measured included the storage modulus (G') and loss tangent (LT) values. Light-backscattering properties, such as the backscatter ratio (R) and the first derivative of light backscatter ratio (R'), were also monitored during fermentation. Fluorescence microscopy was used to observe gel microstructure. The G' values at pH 4.6 were highest in gels made from milk heated at pH 6.7 and lowest in milk heated at pH 6.2, with or without pH adjustment after heating. The G' values at pH 4.6 were lower in samples after adjustment back to pH 6.7 after heating. No maximum in the LT parameter was observed during gelation for yogurts made from milk

  20. The Solubility of Orthorhombic Lysozyme Crystals Obtained at High pH

    SciTech Connect

    Aldabaibeh, Naser; Jones, Matthew J.; Myerson, Allan S.; Ulrich, Joachim

    2009-07-06

    The high pH region of the phase diagram of lysozyme with NaCl as a precipitant was determined. In this region of the phase diagram, lysozyme crystallizes in one of two different orthorhombic modifications, the low and high temperature orthorhombic modifications. The solubility of two modifications was measured at different temperatures, pH values, and NaCl concentrations. Both modifications show a similar dependence on the solution conditions where solubility increases with temperature and decreases with pH and NaCl concentration. The transition temperature between the two modifications was determined from the solubility curves and was shown to increase with pH and NaCl concentration. At pH values close to the isoelectric point (pH 11), the transition temperature becomes independent of NaCl concentration.

  1. Science and Engineering Ph.D. Students' Career Outcomes, by Gender.

    PubMed

    Conti, Annamaria; Visentin, Fabiana

    2015-01-01

    We examine differences in the careers of men and women Ph.D.s from two major European universities. Having performed regression analysis, we find that women are more likely than men to be employed in public administration when the alternatives are either academia or industry. Between the latter two alternatives, women are more likely to be employed in academia. These gender differences persist after accounting for Ph.D.s' and their supervisors' characteristics. Gender gaps are smaller for Ph.D.s with large research outputs and for those who conducted applied research. Restricting the analysis to Ph.D.s who pursued postdoc training, women are less likely than men to be employed in highly ranked universities, even after controlling for their research outputs. Finally, we find gender differences in Ph.D.s' appointment to professorship, which are explained by the Ph.D.s' publication output and the quality of their postdoc training.

  2. A novel pH optical sensor using methyl orange based on triacetylcellulose membranes as support.

    PubMed

    Hosseini, Mohammad; Heydari, Rouhollah; Alimoradi, Mohammad

    2014-07-15

    A novel pH optical sensor based on triacetylcellulose membrane as solid support was developed by using immobilization of methyl orange indicator. The prepared optical sensor was fixed into a flow cell for on-line pH monitoring. Variables affecting sensor performance, such as pH of dye bonding to triacetylcellulose membrane and dye concentration have been fully evaluated and optimized. The calibration curve showed good behavior and precision (RSD<0.4%) in the pH range of 4.0-12.0. No significant variation was observed on sensor response with increasing the ionic strength in the range of 0.0-0.5M of sodium chloride. Determination of pH by using the proposed optical sensor is on-line, quick, inexpensive, selective and sensitive in the pH range of 4.0-12.0.

  3. What took them so long? Explaining PhD delays among doctoral candidates.

    PubMed

    van de Schoot, Rens; Yerkes, Mara A; Mouw, Jolien M; Sonneveld, Hans

    2013-01-01

    A delay in PhD completion, while likely undesirable for PhD candidates, can also be detrimental to universities if and when PhD delay leads to attrition/termination. Termination of the PhD trajectory can lead to individual stress, a loss of valuable time and resources invested in the candidate and can also mean a loss of competitive advantage. Using data from two studies of doctoral candidates in The Netherlands, we take a closer look at PhD duration and delay in doctoral completion. Specifically, we address the question: Is it possible to predict which PhD candidates will experience delays in the completion of their doctorate degree? If so, it might be possible to take steps to shorten or even prevent delay, thereby helping to enhance university competitiveness. Moreover, we discuss practical do's and don'ts for universities and graduate schools to minimize delays.

  4. EMS offshore. A new horizon for paramedics.

    PubMed

    Mallard, A S

    1991-10-01

    The difficulty in getting medical aid to offshore drilling platforms can be a source of life-threatening delays. Recently, some companies have charted new waters by actually stationing EMS crews on their rigs.

  5. Electrochemical control of pH in a hydroponic nutrient solution

    NASA Technical Reports Server (NTRS)

    Schwartzkopf, S. H.

    1986-01-01

    The electrochemical pH control system described was found to provide a feasible alternative method of controlling nutrient solution pH for CELSS applications. The plants grown in nutrient solution in which the pH was controlled electrochemically showed no adverse effects. Further research into the design of a larger capacity electrode bridge for better control is indicated by the results of this experiment, and is currently under way.

  6. 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.

  7. Effect of pH on microstructure and characteristics of cream cheese.

    PubMed

    Monteiro, R R; Tavares, D Q; Kindstedt, P S; Gigante, M L

    2009-03-01

    This study evaluated the effect of pH on the microstructure of cream cheese and compared pH-induced changes in its microstructure with concomitant changes in cheese firmness and meltability. On 4 different days, experimental batches of cultured hot pack cream cheese were manufactured and analyzed for initial chemical composition. The cheeses were then sectioned into samples that were randomly assigned to 7 different treatment groups. Three groups were exposed to ammonia vapor for 1, 3, and 5 min to increase the pH; 3 groups were exposed to acetic acid vapor for 30, 60, and 90 min to decrease the pH; and 1 unexposed group served as the control. After equilibration at 4 degrees C, samples were analyzed for pH, firmness, meltability, and microstructure by scanning electron microscopy. The effects of experimental treatments on cheese pH, firmness, and meltability were analyzed by randomized complete block analysis of variance (ANOVA). Relationships between cheese pH and firmness and meltability were evaluated by regression. Experimental treatments significantly affected cheese pH, firmness, and meltability. Cheese firmness decreased and meltability increased with increasing pH from about pH 4.2 to 6.8. Cheese microstructure also changed dramatically over the same approximate pH range. Specifically, the volume of the protein network surrounding the fat droplets increased markedly with increasing pH, presumably due to casein swelling. These data support the hypothesis that protein-to-water interactions increased as the cheese pH increased, which gave rise to progressive swelling of the casein network, softer texture, and increased meltability.

  8. Effect of initial ph on growth characteristics and fermentation properties of Saccharomyces cerevisiae.

    PubMed

    Liu, Xingyan; Jia, Bo; Sun, Xiangyu; Ai, Jingya; Wang, Lihua; Wang, Cheng; Zhao, Fang; Zhan, Jicheng; Huang, Weidong

    2015-04-01

    As the core microorganism of wine making, Saccharomyces cerevisiae encounter low pH stress at the beginning of fermentation. Effect of initial pH (4.50, 3.00, 2.75, 2.50) on growth and fermentation performance of 3 S. cerevisiae strains Freddo, BH8, Nº.7303, different tolerance at low pH, chosen from 12 strains, was studied. The values of yeast growth (OD600 , colony forming units, cell dry weight), fermentation efficiency (accumulated mass loss, change of total sugar concentration), and fermentation products (ethanol, glycerol, acetic acid, and l-succinic acid) at different pH stress were measured. The results showed that the initial pH of must was a vital factor influencing yeast growth and alcoholic fermentation. Among the 3 strains, strain Freddo and BH8 were more tolerant than Nº.7303, so they were affected slighter than the latter. Among the 4 pH values, all the 3 strains showed adaptation even at pH 2.50; pH 2.75 and 2.50 had more vital effect on yeast growth and fermentation products in contrast with pH 4.50 and 3.00. In general, low initial pH showed the properties of prolonging yeast lag phase, affecting accumulated mass loss, changing the consumption rate of total sugar, increasing final content of acetic acid and glycerol, and decreasing final content of ethanol and l- succinic acid, except some special cases. Based on this study, the effect of low pH on wine products would be better understood and the tolerance mechanism of low pH of S. cerevisiae could be better explored in future.

  9. Treatment with a low pH processing aid to reduce campylobacter counts on broiler parts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluated the low pH processing aid – CMS PoultrypHresh™ (LPPA) to reduce Campylobacter on carcasses (3 groups of 6) collected prior to the chiller that were individually placed into a 38 L container with either 20 L tap water (pH = 7.3) or 20 L of LPPA solution (pH = 1.4) with air agita...

  10. Photochemical Performance of the Acidophilic Red Alga Cyanidium sp. in a pH Gradient

    NASA Astrophysics Data System (ADS)

    Kvíderová, Jana

    2012-06-01

    The acidophilic red alga Cyanidium sp. is one of the dominant mat-forming species in the highly acidic waters of Río Tinto, Spain. The culture of Cyanidium sp., isolated from a microbial mat sample collected at Río Tinto, was exposed to 9 different pH conditions in a gradient from 0.5 to 5 for 24 h and its physiological status evaluated by variable chlorophyll a fluorescence kinetics measurements. Maximum quantum yield was determined after 30 min, 1 h, 2 h, 4 h, 6 h and 24 h of exposure after 15 min dark adaptation. The effect of pH on photochemical activity of Cyanidium sp. was observable as early as 30 min after exposure and the pattern remained stable or with only minor modifications for 24 h. The optimum pH ranged from 1.5 to 2.5. A steep decrease of the photochemical activity was observed at pH below 1 even after 30 min of exposure. Although the alga had tolerated the exposure to pH = 1 for at least 6 h, longer (24 h) exposure resulted in reduction of the photochemical activity. At pH above 2.5, the decline was more moderate and its negative effect on photochemistry was less severe. According to the fluorescence measurements, the red alga Cyanidium sp. is well-adapted to prevailing pH at its original locality at Río Tinto, i.e. pH of 1 to 3. The short-term survival in pH < 1.5 may be adaptation to rare exposures to such low pH in the field. The tolerance of pH above 3 could be caused by adaptation to the microenvironment of the inner parts of microbial mats in which Cyanidium sp. usually dominates and where higher pH could occur due to photosynthetic oxygen production.

  11. Transcriptomic responses to seawater acidification among sea urchin populations inhabiting a natural pH mosaic.

    PubMed

    Evans, Tyler G; Pespeni, Melissa H; Hofmann, Gretchen E; Palumbi, Stephen R; Sanford, Eric

    2017-01-31

    Increasing awareness of spatial and temporal variation in ocean pH suggests some marine populations may be adapted to local pH regimes and will therefore respond differently to present-day pH variation and to long-term ocean acidification. In the Northeast Pacific Ocean, differences in the strength of coastal upwelling cause latitudinal variation in prevailing pH regimes that are hypothesized to promote local adaptation and unequal pH tolerance among resident populations. In this study, responses to experimental seawater acidification were compared among six populations of purple sea urchins (Strongylocentrotus purpuratus) inhabiting areas that differ in their frequency of low pH exposure and that prior research suggests are locally adapted to seawater pH. Transcriptomic analyses demonstrate urchin populations most frequently exposed to low pH seawater responded to experimental acidification by expressing genes within major ATP producing pathways at greater levels than populations encountering low pH less often. Multiple genes within the tricarboxylic acid cycle, electron transport chain, and fatty acid beta oxidation pathways were up-regulated in urchin populations experiencing low pH conditions most frequently. These same metabolic pathways were significantly over-represented among genes both expressed in a population-specific manner and putatively under selection to enhance low pH tolerance. Collectively, these data suggest natural selection is acting on metabolic gene networks in order to redirect ATP toward acid-base regulatory processes and enhance tolerance of seawater acidification. As a trade-off, marine populations more tolerant of low pH may have less energy to put toward other aspects of fitness and to respond to additional ocean change. This article is protected by copyright. All rights reserved.

  12. Articulating Expectations for PhD Candidature upon Commencement: Ensuring Supervisor/Student "Best Fit"

    ERIC Educational Resources Information Center

    Moxham, Lorna; Dwyer, Trudy; Reid-Searl, Kerry

    2013-01-01

    The journey towards completion of a PhD is a bumpy one for many. One of the major factors that influence successful and on-time thesis completion is the relationship that the PhD candidate has with her or his supervisor. This paper presents results from research undertaken using a 12-item survey to collect data from a purposive sample: PhD…

  13. Effect of pH on Cleavage of Glycogen by Vaginal Enzymes

    PubMed Central

    Spear, Greg T.; McKenna, Mary; Landay, Alan L.; Makinde, Hadijat; Hamaker, Bruce; French, Audrey L.; Lee, Byung-Hoo

    2015-01-01

    Glycogen expressed by the lower genital tract epithelium is believed to support Lactobacillus growth in vivo, although most genital isolates of Lactobacillus are not able to use glycogen as an energy source in vitro. We recently reported that α-amylase is present in the genital fluid of women and that it breaks down glycogen into small carbohydrates that support growth of lactobacilli. Since the pH of the lower genital tract can be very low, we determined how low pH affects glycogen processing by α-amylase. α-amylase in saliva degraded glycogen similarly at pH 6 and 7, but activity was reduced by 52% at pH 4. The glycogen degrading activity in nine genital samples from seven women showed a similar profile with an average reduction of more than 50% at pH 4. However, two samples collected from one woman at different times had a strikingly different pH profile with increased glycogen degradation at pH 4, 5 and 6 compared to pH 7. This second pH profile did not correlate with levels of human α-acid glucosidase or human intestinal maltase glucoamylase. High-performance anion-exchange chromatography showed that mostly maltose was produced from glycogen by samples with the second pH profile in contrast to genital α-amylase that yielded maltose, maltotriose and maltotetraose. These studies show that at low pH, α-amylase activity is reduced to low but detectable levels, which we speculate helps maintain Lactobacillus growth at a limited but sustained rate. Additionally, some women have a genital enzyme distinct from α-amylase with higher activity at low pH. Further studies are needed to determine the identity and distribution of this second enzyme, and whether its presence influences the makeup of genital microbiota. PMID:26171967

  14. Ph-like acute lymphoblastic leukemia: a high-risk subtype in adults.

    PubMed

    Jain, Nitin; Roberts, Kathryn G; Jabbour, Elias; Patel, Keyur; Eterovic, Agda Karina; Chen, Ken; Zweidler-McKay, Patrick; Lu, Xinyan; Fawcett, Gloria; Wang, Sa A; Konoplev, Sergej; Harvey, Richard C; Chen, I-Ming; Payne-Turner, Debbie; Valentine, Marcus; Thomas, Deborah; Garcia-Manero, Guillermo; Ravandi, Farhad; Cortes, Jorge; Kornblau, Steven; O'Brien, Susan; Pierce, Sherry; Jorgensen, Jeffrey; Shaw, Kenna R Mills; Willman, Cheryl L; Mullighan, Charles G; Kantarjian, Hagop; Konopleva, Marina

    2017-02-02

    Philadelphia chromosome (Ph)-like acute lymphoblastic leukemia (ALL) is a high-risk subtype of ALL in children. There are conflicting data on the incidence and prognosis of Ph-like ALL in adults. Patients with newly diagnosed B-cell ALL (B-ALL) who received frontline chemotherapy at MD Anderson Cancer Center underwent gene expression profiling of leukemic cells. Of 148 patients, 33.1% had Ph-like, 31.1% had Ph(+), and 35.8% had other B-ALL subtypes (B-other). Within the Ph-like ALL cohort, 61% had cytokine receptor-like factor 2 (CRLF2) overexpression. Patients with Ph-like ALL had significantly worse overall survival (OS), and event-free survival compared with B-other with a 5-year survival of 23% (vs 59% for B-other, P = .006). Sixty-eight percent of patients with Ph-like ALL were of Hispanic ethnicity. The following were associated with inferior OS on multivariable analysis: age (hazard ratio [HR], 3.299; P < .001), white blood cell count (HR, 1.910; P = .017), platelet count (HR, 7.437; P = .005), and Ph-like ALL (HR, 1.818; P = .03). Next-generation sequencing of the CRLF2(+) group identified mutations in the JAK-STAT and Ras pathway in 85% of patients, and 20% had a CRLF2 mutation. Within the CRLF2(+) group, JAK2 mutation was associated with inferior outcomes. Our findings show high frequency of Ph-like ALL in adults, an increased frequency of Ph-like ALL in adults of Hispanic ethnicity, significantly inferior outcomes of adult patients with Ph-like ALL, and significantly worse outcomes in the CRLF2(+) subset of Ph-like ALL. Novel strategies are needed to improve the outcome of these patients.

  15. Development of Non-Invasive Deep Tissue pH Sensor.

    DTIC Science & Technology

    1995-10-01

    effort has demonstrated the feasibility of measuring deep tissue pH using near infrared reflection spectroscopy coupled with partial least squares...LIST OF FIGURES PAGE Figure 1. Diagram of Near- Infrared Fiber-optic Spectroscopy 8 System for Non-Contact pH Measurement in Human or Animal Tissue Figure...delivery that the tissue pH measurement provides. The ability to non-invasively measure tissue oxygenation using near- infrared spectroscopy has been

  16. The Purpose of the PhD: Theorising the Skills Acquired by Students

    ERIC Educational Resources Information Center

    Mowbray, Susan; Halse, Christine

    2010-01-01

    In the past decade there has been a marked push for the development of employability skills to be part of the PhD process. This push is generally by stakeholders from above and outside the PhD process, i.e. government and industry, who view skills as a "summative product" of the PhD. In contrast, our study interviewed stakeholders inside…

  17. Cervical length versus vaginal PH in the second trimester as preterm birth predictor

    PubMed Central

    Foroozanfard, Fatemeh; Tabasi, Zohreh; Mesdaghinia, Elaheh; Sehat, Mojtaba; Mehrdad, Mahdian

    2015-01-01

    Objective: To evaluate diagnostic value of vaginal pH and cervical length measurement in the second trimester of pregnancy as a preterm labor (PTL) predictor. Methods: During a prospective cohort study 438 uncomplicated singleton pregnant women between 18 and 24 weeks of gestation were assessed regarding vaginal PH and cervical length. Vaginal pH was measured using Ph-indicator strips and cervical length was determined using transvaginal ultrasound. The cut-off values for vaginal PH and cervical length were defined as 5 and <30 mm respectively. Results: Vaginal pH of 5 and above was found in 162/438 women (37%) while cervical length <30mm was found in 38/438 (8.7%). The incidence of PTL < 37 weeks was 87/438 (19.9%) while the incidence of early (PTL <34 weeks) was 51/438 (11.6%). Predictive value of higher vaginal PH was significantly more (31%) than vaginal PH<5 (13%) in predicting PTL. As a result, alkaline vaginal PH significantly increases the odds of preterm labor (OR=3.06). Shortened cervical length is better predictor of PTL than higher vaginal PH with positive predictive value of 71% and negative predictive value of 85%. Cervical length less than 30 mm nearly 14-fold increases odds of preterm birth (OR=13.9). Conclusion: Compared to alkaline vaginal PH, shortened cervical length has better value to predict PTL overall. However, regarding early or late PTL, vaginal PH is more accurate to predict late PTL, while cervical length measurement is more appropriate to predict early PTL (<34 weeks). PMID:26101494

  18. Two pH optima of adenosine 5'-triphosphate dependent deoxyribonuclease from Bacillus laterosporus.

    PubMed

    Fujiyoshi, T; Nakayama, J; Anai, M

    1982-08-17

    The various catalytic activities of the ATP-dependent deoxyribonuclease (DNase) of Bacillus laterosporus have pH optima at 6.3 and 8.3. Although the pH profile of ATP-dependent DNase activity on duplex DNA is bell shaped with a maximum at about pH 8.3, ATP-dependent DNAse activity on single-stranded DNA has optima at pH 6.3 and 8.3. ATPase activities dependent on double-stranded and single-stranded DNA have a high bell-shaped peak with a maximum at pH 6.3 with a low and broad shoulder at about pH 8.3. ATP-independent DNase activity also has optima at pH 6.3 and 8.3. The ratio of the amount of ATP hydrolyzed per number of cleaved phosphodiester bonds in DNA increases with decrease in the pH value of the reaction. The ratios obtained at pH 8.3 and 6.3 were respectively about 3 and 22 with duplex DNA as substrate and 5 and 17 with single-stranded DNA as substrate. Formation of a single-stranded region of 15000-20000 nucleotides, which is linked to duplex DNA and about half of which has 3'-hydroxyl termini, was observed at about pH 6.3, but not at above pH 7.5. Furthermore, the optimum concentrations of divalent cations for the activity producing the single-stranded region and the activity hydrolyzing ATP were identical (3 mM Mn2+ or 5 mM Mg2+). Thus the two activities are closely related. These results indicate that the enzyme has two different modes of action on duplex DNA which are modulated by the pH.

  19. 40 CFR 439.4 - General limitation or standard for pH.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false General limitation or standard for pH. 439.4 Section 439.4 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT... limitation or standard for pH. The pH must remain within the range 6.0 to 9.0 in any discharge subject to...

  20. Peptide binding to HLA-DP proteins at pH 5.0 and pH 7.0: a quantitative molecular docking study

    PubMed Central

    2012-01-01

    Background HLA-DPs are class II MHC proteins mediating immune responses to many diseases. Peptides bind MHC class II proteins in the acidic environment within endosomes. Acidic pH markedly elevates association rate constants but dissociation rates are almost unchanged in the pH range 5.0 – 7.0. This pH-driven effect can be explained by the protonation/deprotonation states of Histidine, whose imidazole has a pKa of 6.0. At pH 5.0, imidazole ring is protonated, making Histidine positively charged and very hydrophilic, while at pH 7.0 imidazole is unprotonated, making Histidine less hydrophilic. We develop here a method to predict peptide binding to the four most frequent HLA-DP proteins: DP1, DP41, DP42 and DP5, using a molecular docking protocol. Dockings to virtual combinatorial peptide libraries were performed at pH 5.0 and pH 7.0. Results The X-ray structure of the peptide – HLA-DP2 protein complex was used as a starting template to model by homology the structure of the four DP proteins. The resulting models were used to produce virtual combinatorial peptide libraries constructed using the single amino acid substitution (SAAS) principle. Peptides were docked into the DP binding site using AutoDock at pH 5.0 and pH 7.0. The resulting scores were normalized and used to generate Docking Score-based Quantitative Matrices (DS-QMs). The predictive ability of these QMs was tested using an external test set of 484 known DP binders. They were also compared to existing servers for DP binding prediction. The models derived at pH 5.0 predict better than those derived at pH 7.0 and showed significantly improved predictions for three of the four DP proteins, when compared to the existing servers. They are able to recognize 50% of the known binders in the top 5% of predicted peptides. Conclusions The higher predictive ability of DS-QMs derived at pH 5.0 may be rationalised by the additional hydrogen bond formed between the backbone carbonyl oxygen belonging to the peptide