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Sample records for gamma-hydroxybutyrate ghb precursors

  1. Gamma-Hydroxybutyrate (GHB)

    MedlinePlus

    ... water Scoop Soap Somatomax PM Somsanit Vita-G Water Wolfies Zonked Should I be worried about GHB? Yes. Because GHB has no color or smell, it can easily be slipped into drinks and food. Even a very small amount of GHB may cause a person to "black out" (become unconscious). This is why GHB is ...

  2. Preference for Gamma-Hydroxybutyrate (GHB) in Current Users

    ERIC Educational Resources Information Center

    Roll, John M.; Newton, Thomas; Chudzynski, Joy; Cameron, Jennifer M.; McPherson, Sterling; Fong, Tim; Torrington, Matt

    2012-01-01

    Gamma-hydroxybutyrate (GHB) is a drug with significant abuse potential. The present study aimed to assess the relative value of escalating doses of GHB to current GHB users via the Multiple Choice Procedure (MCP), and to validate that the dose rated highest with the MCP would be self-administered at a greater rate than placebo. Participants were 5…

  3. EXPERIENCES OF GAMMA HYDROXYBUTYRATE (GHB) INGESTION: A FOCUS GROUP STUDY

    PubMed Central

    Barker, Judith C.; Harris, Shana L.; Dyer, Jo E.

    2008-01-01

    GHB (gamma hydroxybutyrate) is a significant new drug of abuse added to the United States Controlled Substance Act in 2000. The majority of the published literature on GHB consists of clinical case reports, mainly from emergency departments, and a collection of laboratory-based studies, focused mainly on anesthesia. While comments about the various experiences and behaviors of human users are often included in such studies or reports, these aspects of GHB are only just beginning to be systematically investigated or detailed. Reported here are data from a qualitative study using focus group methods on the consumption habits, experiences, and beliefs of GHB users. A total of 51 people, 30 men and 21 women, mean age of 31.1±7.6 years (range 18 – 52 years), who report having used GHB for an average of 4.3±2.5 years (range 1–11 years), were interviewed in 10 separate groups held in 2004. This paper discusses broadly the general experience of the GHB ‘high,’ major perceived benefits including sexual responses to the drug, perceived risks and dangers of ingestion, co-ingestion, and various contexts of use. The paper concludes with a discussion of the implications drawn from this information for clinicians treating patients who use GHB. PMID:17703706

  4. BEHAVIORAL EFFECTS OF GAMMA-HYDROXYBUTYRATE (GHB) IN HUMANS

    PubMed Central

    Oliveto, Alison; Gentry, W. Brooks; Pruzinsky, Rhonda; Gonsai, Kishorchandra; Kosten, Thomas R.; Martell, Bridget; Poling, James

    2010-01-01

    Despite the therapeutic use and abuse potential of gamma-hydroxybutyrate (GHB or Xyrem), relatively few studies have examined the behavioral effects of GHB in humans under controlled laboratory conditions. Thus, this eight-session study examined in 10 non substance-abusing volunteers the behavioral effects of GHB at each of the following doses: 0, 0.32, 0.56, 0.75, 1.0, 1.8, 2.4, 3.2 g/70 kg, p.o.. Order of dose testing was random, except that the first two participants received active doses in ascending order and 2.4 g/70 kg was always tested before 3.2 g/70 kg. Prior to drug administration and at several post-drug time points, self-report, observer-report, physiological, and psychomotor performance measures were obtained. Analyses based on area under the curve showed that GHB produced dose-related increases in subjective ratings of sedative-like, stimulant-like, positive mood, and dissociative effects, but no changes in psychomotor performance measures or blood pressure. Analyses based on peak effects generally showed dose-related increases in ratings indicating sedative-like, dissociative, and drug liking, although some measures showed U-shaped dose-related changes. These initial findings suggest that GHB at doses of 0.32–3.2 g/70 kg produces dissociative, sedating and some stimulant-like effects in humans without a history of sedative abuse. PMID:20526195

  5. Self-administration of gamma-hydroxybutyric acid (GHB) precursors gamma-butyrolactone (GBL) and 1,4-butanediol (1,4-BD) in baboons

    PubMed Central

    Goodwin, Amy K.; Kaminski, Barbara J.; Weerts, Elise M.

    2012-01-01

    Rationale Gamma-butyrolactone (GBL) and 1,4-butanediol (1,4-BD) are gamma-hydroxybutyrate (GHB) pro-drugs and drugs of abuse. Objective Given the reports of abuse, and the ease at which GBL and 1,4-BD may be obtained, we investigated the reinforcing of GBL (n=5) and 1,4-BD (n=4) in baboons using IV self-administration procedures. Methods Sessions ran 24 h/day. Each injection was contingent upon completion of a fixed number (120 or 160) of lever responses. A 3-h timeout period followed each injection, limiting the total number of injections to 8/day. Self-administration was first established with cocaine (0.32 mg/kg/injection). GBL (10–130.0 mg/kg/injection), 1,4-BD (10–100 mg/kg/injection) or vehicle were substituted for cocaine at least 15 days. Food pellets were available ad libitum 24 h/day and were contingent upon completion of 10 lever responses. Results GBL (32–100 mg/kg/injection) maintained significantly greater numbers of injections when compared to vehicle in 4 of 5 baboons and mean rates of injection were high (>6 per day) in 3 baboons and moderate in the fourth baboon (4–6 per day). 1,4-BD (78–130 mg/kg/injection) maintained significantly greater numbers of injections when compared to vehicle in only 2 out of 4 baboons and rates were moderate to high in both baboons. Self-injection of these doses of GBL and 1,4-BD generally inhibited food-maintained responding. Conclusions GBL and 1,4-BD have abuse liability. Given that GBL and 1,4-BD are self-administered, are easier to obtain than GHB, and are detected in seized samples, additional legal control measures of these GHB pro-drugs may be needed. PMID:22945514

  6. Gamma-hydroxybutyrate (GHB): a scoping review of pharmacology, toxicology, motives for use, and user groups.

    PubMed

    Brennan, Rebekah; Van Hout, Marie Claire

    2014-01-01

    Gamma hydroxybutyrate (GHB) is a central nervous system depressant with euphoric and relaxant effects. Documentation of GHB prevalence and the underreporting of abuse remains problematic, given the availability of GHB and its precursors γ-butyrolactone (GBL) and 1,4-butanediol (1,4-BD) and the ease of synthesis from kits available on the Internet. The continued abuse of and dependence on GHB, and associated fatalities, present an on-going public health problem. As the drug GHB remains an underresearched topic, a scoping review was chosen as a technique to map the available literature into a descriptive summarized account. PRISMA was used to assist in data retrieval, with subsequent data charting into three key themes (pharmacology and toxicology, outcomes, and user groups). Administered orally, GHB is dose-dependent and popular for certain uses (therapeutic, body enhancement, sexual assault) and amongst user sub groups (recreational party drug users, homosexual men). Despite the low prevalence of use in comparison to other club drugs, rising abuse of the drug is associated with dependence, withdrawal, acute toxicity, and fatal overdose. Clinical diagnosis and treatment is complicated by the co-ingestion of alcohol and other drugs. Limitations of the scoping review and potential for further research and harm reduction initiatives are discussed. PMID:25052883

  7. Illicit gamma-hydroxybutyrate (GHB) and pharmaceutical sodium oxybate (Xyrem): differences in characteristics and misuse.

    PubMed

    Carter, Lawrence P; Pardi, Daniel; Gorsline, Jane; Griffiths, Roland R

    2009-09-01

    There are distinct differences in the accessibility, purity, dosing, and misuse associated with illicit gamma-hydroxybutyrate (GHB) compared to pharmaceutical sodium oxybate. Gamma-hydroxybutyrate sodium and sodium oxybate are the chemical and drug names, respectively, for the pharmaceutical product Xyrem (sodium oxybate) oral solution. However, the acronym GHB is also used to refer to illicit formulations that are used for non-medical purposes. This review highlights important differences between illicit GHB and sodium oxybate with regard to their relative abuse liability, which includes the likelihood and consequences of abuse. Data are summarized from the scientific literature; from national surveillance systems in the U.S., Europe, and Australia (for illicit GHB); and from clinical trials and post-marketing surveillance with sodium oxybate (Xyrem). In the U.S., the prevalence of illicit GHB use, abuse, intoxication, and overdose has declined from 2000, the year that GHB was scheduled, to the present and is lower than that of most other licit and illicit drugs. Abuse and misuse of the pharmaceutical product, sodium oxybate, has been rare over the 5 years since its introduction to the market, which is likely due in part to the risk management program associated with this product. Differences in the accessibility, purity, dosing, and misuse of illicit GHB and sodium oxybate suggest that risks associated with illicit GHB are greater than those associated with the pharmaceutical product sodium oxybate. PMID:19493637

  8. A Web-Based Study of Gamma Hydroxybutyrate (GHB): Patterns, Experiences, and Functions of Use

    PubMed Central

    Stein, LAR; Lebeau, Rebecca; Clair, Mary; Martin, Rosemarie; Bryant, Monte; Storti, Susan; Monti, Peter

    2011-01-01

    GHB (gamma hydroxybutyrate) was developed as a general anesthetic. Due to dosing difficulty and side effects, regular use was discontinued. Medical uses include treating sleep and alcohol disorders. In the 1990s, it was promoted as a supplement and taken to improve mood and sex. GHB and its analogs (gamma butyrolactone and butanediol) were widely available until federal regulations were put into effect with mounting evidence of adverse events. This survey (N = 61) study was conducted to assess patterns, experiences, and functions of use. Much of what is understood regarding GHB treatment is based on hospital case studies for overdose and withdrawal. Not enough is known about prevention, reducing use and associated problems, or relapse. We know little about specific drug effect expectancies, triggers, coping skills, and consequences of use (positive/negative). While the drug treatment literature has a wealth of information to draw upon, GHB-specific information may greatly assist relapse prevention. PMID:21175918

  9. Intravenous self-administration of gamma-hydroxybutyrate (GHB) in baboons

    PubMed Central

    Goodwin, Amy K.; Kaminski, Barbara J.; Griffiths, Roland R.; Ator, Nancy A.; Weerts, Elise M.

    2010-01-01

    Background Abuse of gamma-hydroxybutyrate (GHB) poses a public health concern. In previous studies, intravenous (IV) self-administration of GHB doses up to 10 mg/kg was not maintained in non-human primates under limited-access conditions, which was inconsistent with the usual good correspondence between drugs abused by humans and those self-injected by laboratory animals. Methods Self-administration of GHB was studied in 10 baboons using procedures standard for our laboratory to assess drug abuse liability. Each self-injection depended on completion of 120 or 160 lever responses. Sessions ran continuously; a 3-h timeout limited the number of injections per 24 h to 8. Self-injection was established at 6–8 injections/day with cocaine (0.32 mg/kg/injection) prior to substitution of each GHB dose (3.2–178 mg/kg/injection) or vehicle for 15 days. Food pellets were available 24 h/day. Results GHB maintained significantly greater numbers of injections when compared to vehicle in 6 of the 9 baboons that completed GHB evaluations that included 32 mg/kg/injection or higher. The baboons that self-administered GHB at high rates were ones for which GHB was the first drug each had tested under the 24-hr/day cocaine baseline procedure. Self-injection of the highest doses of GHB decreased food-maintained responding. Conclusions High-dose GHB can function as a reinforcer in non-human primates under 24-h access, but self-administration history may be important. The findings are consistent with the demonstrated abuse liability of GHB in humans, and remove GHB as an exception to the typical good correspondence between those drugs abused by humans and those self-administered by nonhuman primates. PMID:21112162

  10. Symptoms and signs in interpreting Gamma-hydroxybutyrate (GHB) intoxication - an explorative study

    PubMed Central

    2014-01-01

    Background Acute poisoning with gamma-hydroxybutyrate (GHB) has been a serious medical and social problem in different parts of the world including Sweden. GHB is a drug of abuse which acts primarily as central nervous system (CNS) depressants. GHB has serious toxicity, although many young users do not recognise GHB as a dangerous drug. The aim of this pilot study was to explore how symptoms with risk of failure in vital functions would be valued among professionals that encounter GHB intoxication in the emergency phase. Methods A web-based survey focusing on the assessment of vital clinical signs for possible GHB intoxication using a numeric scale was carried out during April and May 2011. The participants, n 105, are all professionals who encounter GHB intoxicated in the emergency phase, but have different levels of training in GHB intoxication, mainly Registered Nurses (RNs) in southwest Sweden, employed in pre-hospital or emergency departments at somatic and most psychiatric health care facilities, as well as police officers who in their work come into contact with drug users. Responses in the survey were scored according to risk of GHB intoxication with serious failure of vital functions. The score value was then referred to a so-called evidence based priority (EBP) scale and analysed using descriptive statistics and Fisher's exact test. Results Cardiac arrest, coma, hypoxia, general convulsions, slow respiratory and heart rate and pale skin are symptoms with the highest risk of serious failure in vital physical functions and were predominantly recognised as such. Conclusion Despite the professionals' different levels of training in GHB intoxication, all of them were relatively well aware of and in accordance regarding the most risky symptoms. The interpretation score for the less risky symptoms and signs of GHB intoxication varied depending on their degree of training. The results should be viewed cautiously, as the size of the professional groups and their general knowledge of critical symptoms of GHB poisoning varied. PMID:24758357

  11. Prevalence of gamma-hydroxybutyrate (GHB) in serum samples of amphetamine, metamphetamine and ecstasy impaired drivers.

    PubMed

    Dresen, S; Kempf, J; Weinmann, W

    2007-12-20

    Two hundred and forty-seven serum samples which have been collected by police during roadside testing and have been found positive for amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA) and/or 3,4-methylenedioxyethamphetamine (MDE) were analyzed for gamma-hydroxybutyrate (GHB). Serum samples were spiked with deuterated GHB as internal standard and acetonitrile was added to achieve dilution and protein precipitation. Samples were analyzed with a LC-MS/MS system operated in the multiple reaction monitoring mode (MRM) using a TurboIonSpray source. Chromatographic separation was achieved using a Synergi Polar RP column applying a gradient elution with a runtime of 15 min. To differentiate between endogenous and exogenously administered GHB a cut-off concentration of 10 microg/mL was applied. Five samples exceeded this concentration and were found positive for GHB. These samples were only found positive for amphetamine but no other amphetamine derivatives were detected, while in three samples THC and in one sample cocaine, benzoylecgonine and ethanol were found. PMID:17383132

  12. [Gamma-hydroxybutyric acid (GHB): more than a date rape drug, a potentially addictive drug].

    PubMed

    Karila, Laurent; Novarin, Johanne; Megarbane, Bruno; Cottencin, Olivier; Dally, Sylvain; Lowenstein, William; Reynaud, Michel

    2009-10-01

    According to available information, GHB and its precursors--gamma-butyrolactone (GBL) and 1,4-butanediol (1,4BD)--are used especially in a nightlife scene characterized by the search for amplified sensations through the combination of electronic music, marathon dancing, and substance abuse. Evidence indicates that GHB/GHL is used particularly in some subpopulations and in places, such as in gay nightclubs. Commonly known as Gorliquid ecstasy, it was misused in the 1980s for its bodybuilding effects and in the 1990s as a recreational drug at music venues. In the same period, media coverage of the use of GHB in sexual assault (often referred to as date rape) brought the drug into the spotlight. GHB/GHL addiction is a recognized clinical entity evidenced by severe withdrawal symptoms when the drug is abruptly discontinued after regular or chronic use. There is evidence that negative health and social consequences may occur in recreational and chronic users. Nonfatal overdoses and deaths related to GHB have been reported. These undesirable effects and especially the deaths appear to have prompted campaigns to limit the use of GHB. Clinicians must also be aware of GBL, which is being sold and used as a substitute for GHB. PMID:19762202

  13. Monitoring of the interconversion of gamma-butyrolactone (GBL) to gamma hydroxybutyric acid (GHB) by Raman spectroscopy.

    PubMed

    Munshi, Tasnim; Brewster, Victoria L; Edwards, Howell G M; Hargreaves, Michael D; Jilani, Shelina K; Scowen, Ian J

    2013-08-01

    Gamma-hydroxybutyric acid (GHB) is a drug-of-abuse that has recently become associated with drug-facilitated sexual assault, known as date rape. For this reason the drug is commonly found 'spiked' in alcoholic beverages. When GHB is in solution it may undergo conversion into the corresponding lactone, Gamma-butyrolactone (GBL). Studies have been carried out to determine the detection limits of GHB and GBL in various solutions by Raman spectroscopy and to monitor the interconversion of GHB and GBL in solution with different pH conditions and temperature. In this study, a portable Raman spectrometer was used to study the interconversion of GHB and GBL in water and ethanol solutions as a function of pH, time, and temperature. The aim of this was to determine the optimum pH range for conversion in order to relate this to the pH ranges that the drug is likely to be subjected to, first in spiked beverages and secondly after ingestion in the digestive system. The aim was also to identify a timescale for this conversion in relation to possible scenarios, for example if GHB takes a number of hours to convert to GBL, it is likely for the beverage to be ingested before esterification can take place. GHB and GBL were then spiked into a selection of beverages of known pH in order to study the stability of GHB and GBL in real systems. PMID:23225646

  14. Estimation of gamma-hydroxybutyrate (GHB) co-consumption in serum samples of drivers positive for amphetamine or ecstasy.

    PubMed

    Lott, S; Musshoff, F; Madea, B

    2012-09-10

    There is no toxicological analysis of gamma-hydroxybutyrate (GHB) applied routinely in cases of driving under influence (DUI); therefore the extent of consumption of this drug might be underestimated. Its consumption is described as occurring often concurrently with amphetamine or ecstasy. This study examines 196 serum samples which were collected by police during road side testing for GHB. The samples subject to this study have already been found to be positive for amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA) and/or 3,4-methylenedioxyethamphetamine (MDEA). Analysis has been performed by LC/MS/MS in the multiple reaction monitoring (MRM) mode. Due to its polarity, chromatographic separation of GHB was achieved by a HILIC column. To differentiate endogenous and exogenous levels of GHB, a cut-off concentration of 4μg/ml was applied. Of the 196 samples, two have been found to be positive for GHB. Of these samples, one sample was also positive for amphetamine and one for MDMA. Whilst other amphetamine derivates were not detected in these samples, both samples were found to be positive for cannabinoids. These results suggest that co-consumption of GHB with amphetamine or ecstasy is relatively low (1%) for the collective of this study. PMID:22554869

  15. Low-carb diets, fasting and euphoria: Is there a link between ketosis and gamma-hydroxybutyrate (GHB)?

    PubMed

    Brown, Andrew J

    2007-01-01

    Anecdotal evidence links the initial phase of fasting or a low-carbohydrate diet with feelings of well-being and mild euphoria. These feelings have often been attributed to ketosis, the production of ketone bodies which can replace glucose as an energy source for the brain. One of these ketone bodies, beta-hydroxybutyrate (BHB), is an isomer of the notorious drug of abuse, GHB (gamma-hydroxybutyrate). GHB is also of interest in relation to its potential as a treatment for alcohol and opiate dependence and narcolepsy-associated cataplexy. Here I hypothesize that, the mild euphoria often noted with fasting or low-carbohydrate diets may be due to shared actions of BHB and GHB on the brain. Specifically, I propose that BHB, like GHB, induces mild euphoria by being a weak partial agonist for GABA(B) receptors. I outline several approaches that would test the hypothesis, including receptor binding studies in cultured cells, perception studies in trained rodents, and psychometric testing and functional magnetic resonance imaging in humans. These and other studies investigating whether BHB and GHB share common effects on brain chemistry and mood are timely and warranted, especially when considering their structural similarities and the popularity of ketogenic diets and GHB as a drug of abuse. PMID:17011713

  16. Gamma-hydroxybutyrate (GHB) induces cognitive deficits and affects GABAB receptors and IGF-1 receptors in male rats.

    PubMed

    Johansson, Jenny; Grnbladh, Alfhild; Hallberg, Mathias

    2014-08-01

    In recent years, the abuse of the club drug gamma-hydroxybutyrate (GHB) has become increasingly popular among adolescents. The drug induces euphoria but can also result in sedation, anaesthesia as well as short-term amnesia. In addition, the abuse of GHB causes cognitive impairments and the mechanism by which GHB induces these impairments is not clarified. The present study investigates the impact of GHB treatment on spatial learning and memory using a water maze (WM) test in rats. Furthermore, the behavioural data is combined with an autoradiographic analysis of the GABAB and the IGF-1 receptor systems. The results demonstrate that the animals administered with GHB display an impaired performance in the WM test as compared to controls. In addition, significant alterations in GABAB and IGF-1 receptor density as well as GABAB receptor functionality, were observed in several brain regions associated with cognitive functions e.g. hippocampus. To conclude, our findings suggest that GHB treatment can affect spatial learning and memory, and that this outcome at least to some extent is likely to involve both GABAB and IGF-1 receptors. PMID:24786330

  17. The Impact of Gamma Hydroxybutyrate (GHB) Legal Restrictions on Patterns of Use: Results from an International Survey

    PubMed Central

    Anderson, IB; Kim-Katz, SY; Dyer, JE; Blanc, PD

    2009-01-01

    Aims To conduct an Internet-based survey of GHB use, identifying differences by respondent residence. Methods We recruited GHB-knowledgeable persons via “social networking Internet sites.” Individuals (n=314) or groups (n=66) were approached based on GHB-use testimonials. Data collected location, use, reason for cessation (if applicable). Findings We recruited 155 GHB users. U.S. respondents (53 of 70; 76%) compared to non-U.S. respondents (38 of 85; 45%) were older and more highly educated (p<0.05) but manifest a 3-fold greater adjusted odds of GHB cessation (Odds Ratio [OR] 3.1; 95% CI 1.4–6.9; p < 0.05). Of the 80 respondents stating reason for cessation, 36 (45%) cited legal risk, price, or access; 44 (55%) cited health or related concerns. U.S. compared to non-U.S. respondents more frequently invoked legal and related concerns (OR 2.5; 95% CI 0.99–6.3; p=0.05). In a nested analysis, narrowly stated legal (n=4/5 U.S.) versus health (n=6/18 U.S.) reasons differed by location (p=0.048, one-tailed). Conclusions In the U.S., where GHB has stricter legal penalties, GHB cessation is more likely, with legal and related reasons more commonly invoked for cessation. These findings support a link between declining U.S. GHB abuse and more stringent restrictions; although other un-assessed factors may also explain this association. The Impact of Gamma Hydroxybutyrate (GHB) Legal Restrictions on Patterns of Use: Results from an International Survey PMID:20953310

  18. [Current knowledge on gamma-hydroxybutyric acid (GHB), gamma-butyrolactone (GBL) and 1 ,4-butanediol (1,4-BD)].

    PubMed

    Dematteis, Maurice; Pennel, Lucie; Mallaret, Michel

    2012-05-01

    Gamma-hydroxybutyric acid (GHB) is an old anaesthetic drug which was misused in the 80-90's as an anabolic agent (bodybuilding), recreational drug (drunkenness, euphoric, disinhibiting and aphrodisiac effects) and as a date rape drug (disinhibiting, hypnotic and amnesic effects). Its use in the general population is low, and mainly concerns gay population in nightclubs and young people in parties. The intoxications, above all with alcohol combination, can be severe, with coma and breathing depression, or even fatal. Chronic use leads to psychic and physical dependence; withdrawal syndrome can be severe, with agitation and delirium. In 1999, GHB classification as a narcotic resulted in the increased use of GHB prodrugs gamma-butyrolactone (GBL) and 1,4-butanediol (1,4-BD), which were easily commercially available as solvent and cleaning products. Like GHB, they have a narrow window of use, and share similar toxicity. Their increased cases of recreational use and of severe drug intoxication, abuse and dependence, led the French Ministry of Health in 2011 to prohibit their sale and transfer to the public. PMID:22730800

  19. Endogenous gamma-aminobutyric acid (GABA)(A) receptor active neurosteroids and the sedative/hypnotic action of gamma-hydroxybutyric acid (GHB): a study in GHB-S (sensitive) and GHB-R (resistant) rat lines.

    PubMed

    Barbaccia, Maria Luisa; Carai, Mauro A M; Colombo, Giancarlo; Lobina, Carla; Purdy, Robert H; Gessa, Gian Luigi

    2005-07-01

    In the rat brain, gamma-hydroxybutyric-acid (GHB) increases the concentrations of 3alpha-hydroxy,5alpha-pregnan-20-one (allopregnanolone, 3alpha,5alpha-THP) and 3alpha,21-dihydroxy,5alpha-pregnan-20-one (allotetrahydrodeoxycorticosterone/3alpha,5alphaTHDOC), two neurosteroids acting as positive allosteric modulators of gamma-aminobutyric acid (GABA)(A) receptors. This study was aimed at assessing whether neurosteroids play a role in GHB-induced loss of righting reflex (LORR). Basal and GHB-stimulated brain concentrations of endogenous 3alpha,5alpha-THP and 3alpha,5alpha-THDOC were analyzed in two rat lines, GHB-sensitive (GHB-S) and GHB-resistant (GHB-R), selectively bred for opposite sensitivity to GHB-induced sedation/hypnosis. Basal neurosteroid concentrations were similar in brain cortex of the two rat lines. However, in male GHB-S rats, administration of GHB (1000 mg/kg, i.p., 30 min) increased brain cortical concentrations of 3alpha,5alpha-THP and 3alpha,5alpha-THDOC 7- and 2.5-fold, respectively, whilst male GHB-R animals displayed only a 4- and 2-fold increase, respectively. In GHB-S rats this increase lasted up to 90 min and declined 180 min following GHB administration, a time course that matches LORR onset and duration. In contrast, in GHB-R rats, which failed to show GHB-induced LORR, brain cortical 3alpha,5alpha-THP and 3alpha,5alpha-THDOC had returned to control values within 90 min. At onset of LORR, a similar increase in brain cortical levels of 3alpha,5alpha-THP and 3alpha,5alpha-THDOC (2-3-fold) was observed in GHB-S female rats and in the few female GHB-R rats that lost the righting reflex after GHB administration, but not in female GHB-R rats failing to show LORR. Sub-hypnotic doses (7.5 and 12.5 mg/kg, i.p.) of pregnanolone, administered 10 min before GHB, dose-dependently facilitated the expression of GHB-induced LORR in GHB-R male rats. These results suggest that the GHB-induced increases of brain 3alpha,5alpha-THP and 3alpha,5alpha-THDOC concentrations are implicated in the eliciting of the sedative/hypnotic action of GHB. PMID:15992580

  20. Gamma-hydroxybutyric acid (GHB) measurement by GC-MS in blood, urine and gastric contents, following an acute intoxication in Belgium.

    PubMed

    Bodson, Q; Denooz, R; Serpe, P; Charlier, C

    2008-01-01

    Gamma-hydroxybutyrate (GHB, sodium oxybate) is a compound related to neuromodulator gamma-aminobutyric acid (GABA), emerging as a recreational drug of abuse and as a rape drug. GHB-related emergencies have dramatically increased in the 1990s, but a decrease is observed since 2000. We describe the case of an acute GHB intoxication in a 28-year-old male who fell unconscious after ingestion of a mouthful of an unknown beverage, and required medical support for 2 days. A cocaine abuse was also detected by preliminary toxicological screening, but the clinical presentation was not typical of cocaine intoxication. A simple liquid-liquid extraction was used for quantitation of GHB, followed by disilyl-derivatization and analysis in selective ion monitoring (SIM) mode by gas chromatography-mass spectrometry (GC-MS), using GHB-d6 as internal standard. High concentrations of GHB were detected in urine (3020 mg/L) and gastric contents (71487 mg/L) at admission. After a 6-hours delay, GHB was still present in urine at 2324 mg/L and in blood at 43 mg/L. The clinical symptoms of cocaine intoxication were diminished by GHB consumption, and the cerebral scan was modified. Attention must thus be paid to acute intoxications with surprising clinical symptoms, and GHB has probably to be added to the preliminary toxicological screening. Data available regarding GHB are briefly reviewed, and our results are compared with previously published reports of non-fatal GHB intoxication. PMID:18714853

  1. A critical evaluation of the gamma-hydroxybutyrate (GHB) model of absence seizures.

    PubMed

    Venzi, Marcello; Di Giovanni, Giuseppe; Crunelli, Vincenzo

    2015-02-01

    Typical absence seizures (ASs) are nonconvulsive epileptic events which are commonly observed in pediatric and juvenile epilepsies and may be present in adults suffering from other idiopathic generalized epilepsies. Our understanding of the pathophysiological mechanisms of ASs has been greatly advanced by the availability of genetic and pharmacological models, in particular the γ-hydroxybutyrate (GHB) model which, in recent years, has been extensively used in studies in transgenic mice. GHB is an endogenous brain molecule that upon administration to various species, including humans, induces not only ASs but also a state of sedation/hypnosis. Analysis of the available data clearly indicates that only in the rat does there exist a set of GHB-elicited behavioral and EEG events that can be confidently classified as ASs. Other GHB activities, particularly in mice, appear to be mostly of a sedative/hypnotic nature: thus, their relevance to ASs requires further investigation. At the molecular level, GHB acts as a weak GABA-B agonist, while the existence of a GHB receptor remains elusive. The pre- and postsynaptic actions underlying GHB-elicited ASs have been thoroughly elucidated in thalamus, but little is known about the cellular/network effects of GHB in neocortex, the other brain region involved in the generation of ASs. PMID:25403866

  2. A Critical Evaluation of the Gamma-Hydroxybutyrate (GHB) Model of Absence Seizures

    PubMed Central

    Venzi, Marcello; Di Giovanni, Giuseppe; Crunelli, Vincenzo

    2015-01-01

    Typical absence seizures (ASs) are nonconvulsive epileptic events which are commonly observed in pediatric and juvenile epilepsies and may be present in adults suffering from other idiopathic generalized epilepsies. Our understanding of the pathophysiological mechanisms of ASs has been greatly advanced by the availability of genetic and pharmacological models, in particular the γ-hydroxybutyrate (GHB) model which, in recent years, has been extensively used in studies in transgenic mice. GHB is an endogenous brain molecule that upon administration to various species, including humans, induces not only ASs but also a state of sedation/hypnosis. Analysis of the available data clearly indicates that only in the rat does there exist a set of GHB-elicited behavioral and EEG events that can be confidently classified as ASs. Other GHB activities, particularly in mice, appear to be mostly of a sedative/hypnotic nature: thus, their relevance to ASs requires further investigation. At the molecular level, GHB acts as a weak GABA-B agonist, while the existence of a GHB receptor remains elusive. The pre- and postsynaptic actions underlying GHB-elicited ASs have been thoroughly elucidated in thalamus, but little is known about the cellular/network effects of GHB in neocortex, the other brain region involved in the generation of ASs. PMID:25403866

  3. Identification of the date-rape drug GHB and its precursor GBL by Raman spectroscopy.

    PubMed

    Brewster, Victoria L; Edwards, Howell G M; Hargreaves, Michael D; Munshi, Tasnim

    2009-01-01

    Gamma hydroxybutyric acid (GHB), also known as 'liquid ecstasy', has recently become associated with drug-facilitated sexual assaults, known colloquially as 'date rape', due to the ability of the drug to cause loss of consciousness. The drug is commonly found 'spiked' into alcoholic beverages, as alcohol increases its sedative effects. Gamma hydroxybutyric acid and the corresponding lactone gamma-butyrolactone (GBL) will reach an equilibrium in solution which favours the lactone in basic conditions and GHB in acidic conditions (less than pH 4). Therefore, we have studied both GHB and GBL, as a mildly acidic beverage 'spiked' with GHB will contain both GHB and GBL. We report the analysis of GHB as a sodium salt and GBL, its precursor, using bench-top and portable Raman spectroscopy. It has been demonstrated that we are able to detect GHB and GBL in a variety of containers including colourless and amber glass vials, plastic vials and polythene bags. We have also demonstrated the ability to detect both GBL and GHB in a range of liquid matrices simulating 'spiked' beverages. PMID:20355156

  4. Report on the analysis of common beverages spiked with gamma-hydroxybutyric acid (GHB) and gamma-butyrolactone (GBL) using NMR and the PURGE solvent-suppression technique.

    PubMed

    Lesar, Casey T; Decatur, John; Lukasiewicz, Elaan; Champeil, Elise

    2011-10-10

    In forensic evidence, the identification and quantitation of gamma-hydroxybutyric acid (GHB) in "spiked" beverages is challenging. In this report, we present the analysis of common alcoholic beverages found in clubs and bars spiked with gamma-hydroxybutyric acid (GHB) and gamma-butyrolactone (GBL). Our analysis of the spiked beverages consisted of using (1)H NMR with a water suppression method called Presaturation Utilizing Relaxation Gradients and Echoes (PURGE). The following beverages were analyzed: water, 10% ethanol in water, vodka-cranberry juice, rum and coke, gin and tonic, whisky and diet coke, white wine, red wine, and beer. The PURGE method allowed for the direct identification and quantitation of both compounds in all beverages except red and white wine where small interferences prevented accurate quantitation. The NMR method presented in this paper utilizes PURGE water suppression. Thanks to the use of a capillary internal standard, the method is fast, non-destructive, sensitive and requires no sample preparation which could disrupt the equilibrium between GHB and GBL. PMID:21775083

  5. Gamma-hydroxybutyrate, acting through an anti-apoptotic mechanism, protects native and amyloid-precursor-protein-transfected neuroblastoma cells against oxidative stress-induced death.

    PubMed

    Wendt, G; Kemmel, V; Patte-Mensah, C; Uring-Lambert, B; Eckert, A; Schmitt, M J; Mensah-Nyagan, A G

    2014-03-28

    Clinical observations suggested that gamma-hydroxybutyrate (GHB) protects nerve cells against death but the direct proofs are missing. Here, we combined several approaches to investigate GHB capacity to protect human neuroblastoma SH-SY5Y cells against hydrogen peroxide (H2O2)-induced death. To increase the patho-physiological relevancy of our study, we used native SH-SY5Y cells and SH-SY5Y cells stably transfected with the wild-type amyloid-precursor-protein (APPwt) or control-vector-pCEP4. Trypan Blue exclusion and MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium-bromide) assays combined with pharmacological analyses showed that H2O2 reduced native and genetically modified cell viability and APPwt-transfected cells were the most vulnerable. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and activated caspase-3 staining assessed by flow cytometry revealed a basally elevated apoptotic signal in APPwt-transfected cells. Reverse-transcription, real-time quantitative polymerase chain reaction (qPCR) and Western blotting showed that mRNA and protein basal ratios of apoptotic modulators Bax/Bcl-2 were also high in APPwt-transfected cells. GHB efficiently and dose-dependently rescued native and genetically modified cells from H2O2-induced death. Interestingly, GHB, which strongly decreased elevated basal levels of TUNEL-staining, activated caspase 3-labeling and Bax/Bcl-2 in APPwt-transfected cells, also counteracted H2O2-evoked increased apoptotic markers in native and genetically modified SH-SY5Y cells. Since GHB did not promote cell proliferation, anti-apoptotic action through the down-regulation of Bax/Bcl-2 ratios and/or caspase 3 activity appears as a critical mechanism involved in GHB-induced protection of SH-SY5Y cells against APPwt-overexpression- or H2O2-evoked death. Altogether, these results, providing multi-parametric evidence for the existence of neuroprotective action of GHB, also open interesting perspectives for the development of GHB analog-based strategies against neurodegeneration or nerve cell death. PMID:24456637

  6. [First report of lethal gamma-hydroxybutyrate (GHB) intoxication after consumption of gamma-butyrolactone (GBL) in Lower Saxony].

    PubMed

    Fieguth, Armin; Albrecht, Knut; Weller, Jens-Peter; Kühnle, Rolf; Teske, Jörg

    2009-01-01

    A 25-year-old drug addict died from an overdose of GBL after mistaking it for water in preparing a dilution. He realized his error and wrote a call for help in the chat room of a drug forum, so that we know the time, type and approximate amount of drug consumed. The deceased had written numerous contributions in this drug forum before, which provide further information on his drug habits and the duration of the abuse of GHB, GBL and other drugs. According to the Criminal Investigation Department of Lower Saxony, this is the first death due to GHB/GBL reported in Lower Saxony. PMID:19323150

  7. [Life threatening symptoms of withdrawal of gamma-hydroxybutyrate].

    PubMed

    Veerman, S R T; Dijkstra, H N; Liefting-Kluft, I

    2010-01-01

    Acute psychosis and extreme agitation brought about by gamma-hydroxybutyrate GHB withdrawal can be life-threatening. In order to prevent states of excitement accompanied by aggression and somatic complications it is advisable to intervene by administering strong sedatives. It is argued that GHB should be tapered off as an alternative treatment for fixation and high doses of benzodiazepines. PMID:20544599

  8. A potential new metabolite of gamma-hydroxybutyrate: sulfonated gamma-hydroxybutyric acid.

    PubMed

    Hanisch, Stephanie; Stachel, Nicole; Skopp, Gisela

    2016-03-01

    Detection of gamma-hydroxybutyric acid (GHB) became crucial in many clinical and forensic settings due to its increasing use for recreational purposes and drug-facilitated sexual assault. Its narrow window of detection of about 3-12 h in urine represents a major problem. Analogous to ethyl glucuronide, the recently identified GHB-glucuronide exhibits a longer window of detection than the parent drug. It appeared reasonable that a sulfonated metabolite of GHB (GHB-SUL) will also be formed. Due to the lack of an appropriate standard, GHB was incubated with a human liver cytosolic fraction to produce GHB-SUL. Following development of a liquid chromatography/tandem mass spectrometry (LC-MS/MS) assay to measure GHB and GHB-SUL, authentic urine samples (n = 5) were tested for GHB-SUL. These investigations revealed detectable signals of both GHB and GHB-SUL, strongly indicating that GHB is not only glucuronidated but also sulfonated. Given that sulfonated metabolites generally have longer half-life times than the corresponding free drugs, GHB-SUL may serve as a biomarker of GHB misuse along with its glucuronide. PMID:26210636

  9. The role of GABAB receptors in the discriminative stimulus effects of gamma-hydroxybutyrate in rats: time course and antagonism studies.

    PubMed

    Carter, Lawrence P; Flores, Lauren R; Wu, Huifang; Chen, Weibin; Unzeitig, Andrew W; Coop, Andy; France, Charles P

    2003-05-01

    gamma-Hydroxybutyrate (GHB) is a neurotransmitter in brain and an emerging drug of abuse, although its mechanism of action is poorly understood. This study characterized the role of GABA(A), GABA(B), and other receptors in the discriminative stimulus effects of GHB. Eight rats reliably discriminated 200 mg/kg GHB from saline after a median of 35 (range: 23-41) training sessions. GHB, a metabolic precursor 1,4-butanediol (1,4-BDL), and the GABA(B) agonist (+/-)baclofen all occasioned greater than 83% responding on the GHB lever. The onset of action was similar for GHB and 1,4-BDL; however, 1,4-BDL exhibited a longer duration of action than GHB. The GHB precursor gamma-butyrolactone, the benzodiazepine diazepam, the neuroactive steroid pregnanolone, the opioid agonist morphine, and the N-methyl-d-aspartate antagonist ketamine elicited substantial GHB-appropriate responding, although none occasioned greater than 66% drug-lever responding. The barbiturate pentobarbital and the GABA(A) receptor agonist muscimol did not occasion greater than 17% drug-lever responding at any dose tested. The benzodiazepine antagonist flumazenil attenuated GHB-lever responding occasioned by diazepam, but not GHB. The GABA(B) receptor antagonist CGP 35348 antagonized GHB-lever responding occasioned by baclofen or GHB. Small doses of the purported GHB receptor antagonist (2E)-(5-hydroxy-5,7,8,9-tetrahydro-6H-benzo[a][7]annulen-6-ylidene ethanoic acid (NCS-382) attenuated partially the effects of GHB, whereas larger doses of NCS-382 alone occasioned partial GHB-lever responding. These results implicate GABA(B) mechanisms in the discriminative stimulus effects of GHB and further suggest that the effects of 1,4-BDL under these conditions result from its conversion to GHB. That NCS-382 shares effects with GHB could explain the lack of antagonism reported for NCS-382 in some studies. PMID:12606639

  10. Source inference of exogenous gamma-hydroxybutyric acid (GHB) administered to humans by means of carbon isotopic ratio analysis: novel perspectives regarding forensic investigation and intelligence issues.

    PubMed

    Marclay, François; Saudan, Christophe; Vienne, Julie; Tafti, Mehdi; Saugy, Martial

    2011-05-01

    γ-Hydroxybutyric acid (GHB) is an endogenous short-chain fatty acid popular as a recreational drug due to sedative and euphoric effects, but also often implicated in drug-facilitated sexual assaults owing to disinhibition and amnesic properties. Whilst discrimination between endogenous and exogenous GHB as required in intoxication cases may be achieved by the determination of the carbon isotope content, such information has not yet been exploited to answer source inference questions of forensic investigation and intelligence interests. However, potential isotopic fractionation effects occurring through the whole metabolism of GHB may be a major concern in this regard. Thus, urine specimens from six healthy male volunteers who ingested prescription GHB sodium salt, marketed as Xyrem(®), were analysed by means of gas chromatography/combustion/isotope ratio mass spectrometry to assess this particular topic. A very narrow range of δ(13)C values, spreading from -24.81‰ to -25.06‰, was observed, whilst mean δ(13)C value of Xyrem(®) corresponded to -24.99‰. Since urine samples and prescription drug could not be distinguished by means of statistical analysis, carbon isotopic effects and subsequent influence on δ(13)C values through GHB metabolism as a whole could be ruled out. Thus, a link between GHB as a raw matrix and found in a biological fluid may be established, bringing relevant information regarding source inference evaluation. Therefore, this study supports a diversified scope of exploitation for stable isotopes characterized in biological matrices from investigations on intoxication cases to drug intelligence programmes. PMID:21455654

  11. GHB

    MedlinePlus

    ... form. Liquid GHB has no smell and no color. When added to a drink, it can have no taste. Because GHB causes memory loss and drowsiness and is easily slipped into drinks, it's known as a " date rape " drug. Short-Term Effects GHB slows brain activity. Our brains produce ...

  12. Central and Peripheral Metabolic Changes Induced by Gamma-Hydroxybutyrate

    PubMed Central

    Luca, Gianina; Vienne, Julie; Vaucher, Angélique; Jimenez, Sonia; Tafti, Mehdi

    2015-01-01

    Study Objectives: Gamma-hydroxybutyrate (GHB) was originally introduced as an anesthetic but was first abused by bodybuilders and then became a recreational or club drug.1 Sodium salt of GHB is currently used for the treatment of cataplexy in patients with narcolepsy. The mode of action and metabolism of GHB is not well understood. GHB stimulates growth hormone release in humans and induces weight loss in treated patients, suggesting an unexplored metabolic effect. In different experiments the effect of GHB administration on central (cerebral cortex) and peripheral (liver) biochemical processes involved in the metabolism of the drug, as well as the effects of the drug on metabolism, were evaluated in mice. Design: C57BL/6J, gamma-aminobutyric acid B (GABAB) knockout and obese (ob/ob) mice were acutely or chronically treated with GHB at 300 mg/kg. Measurements and Results: Respiratory ratio decreased under GHB treatment, independent of food intake, suggesting a shift in energy substrate from carbohydrates to lipids. GHB-treated C57BL/6J and GABAB null mice but not ob/ob mice gained less weight than matched controls. GHB dramatically increased the corticosterone level but did not affect growth hormone or prolactin. Metabolome profiling showed that an acute high dose of GHB did not increase the brain GABA level. In the brain and the liver, GHB was metabolized into succinic semialdehyde by hydroxyacid-oxoacid transhydrogenase. Chronic administration decreased glutamate, s-adenosylhomocysteine, and oxidized gluthathione, and increased omega-3 fatty acids. Conclusions: Our findings indicate large central and peripheral metabolic changes induced by gamma-hydroxybutyrate (GHB) with important relevance to its therapeutic use. Citation: Luca G, Vienne J, Vaucher A, Jimenez S, Tafti M. Central and peripheral metabolic changes induced by gamma-hydroxybutyrate. SLEEP 2015;38(2):305–313. PMID:25515097

  13. Gamma-hydroxybutyric acid stability and formation in blood and urine.

    PubMed

    Beránková, Katerina; Mutnanská, Katerina; Balíková, Marie

    2006-09-12

    Gamma-hydroxybutyric acid (GHB) can cause problems in interpretation of toxicological findings due to its endogenous nature, significant production in tissues after death and potential formation in stored samples. Our study was designed to determine the influence of storage conditions on GHB levels and its possible in vitro formation in blood and urine in cases where no exogenous use of GHB or its precursors was suspected. The samples were prepared by validated method based on liquid-liquid reextraction with adipic acid internal standard and MSTFA derivatization and assayed on a GC-MS operating in EI SIM mode. The first part of the study was performed with pooled blood and urine samples obtained from living and deceased subjects stored with and without NaF (1% w/v) at 4 and -20 degrees C over 8 months. In ante-mortem samples (both blood and urine) no significant GHB production was found. After 4 months of storage, the substantial GHB rise up to 100 mg/Lwas observed in post-mortem blood stored at 4 degrees C without NaF with subsequent gradual decrease in following months. The inhibition of GHB production was apparent during storage in NaF treated frozen blood samples. In post-mortem urine only slight temporary GHB levels were ascertained (up to 8 mg/L). The second part of our study was aimed to analyse 20 individual post-mortem blood samples stored at 4 degrees C for 16-27 days between autopsy and analysis without preservation followed by storage at 4 degrees C with NaF for 4 months. The temporary GHB production with maximum of 28 mg/Lwas detected in some samples. PMID:16857333

  14. GHB-C rats: the control line of GHB-sensitive (GHB-S) and GHB-resistant (GHB-R) rats.

    PubMed

    Lobina, Carla; Colombo, Giancarlo; Orrù, Alessandro; Maccioni, Paola; Gessa, Gian Luigi; Carai, Mauro A M

    2005-05-01

    Gamma-hydroxybutyric acid (GHB)-sensitive (GHB-S) and GHB-resistant (GHB-R) rats have been selectively bred for their opposite sensitivity to the sedative/hypnotic effect of GHB. This opposite sensitivity has been found to generalize to the GABA(B) receptor agonist, baclofen. A control line [named GHB-control (GHB-C)] has been derived from the foundation stock of GHB-S and GHB-R rats. GHB-C rats have been bred without any evaluation of their sensitivity to GHB. The experiments described here were designed to evaluate the sensitivity of GHB-C rats, from the 13th generation, to the sedative/hypnotic effect of GHB (1 g/kg, i.p.) and baclofen (20 mg/kg, i.p.). All measures (onset, sleep time and r = sleep time/onset) of sensitivity to GHB- and baclofen-induced sedation/hypnosis in GHB-C rats were significantly different from and intermediate to those recorded in GHB-S and GHB-R rats. Furthermore, these values were similar to those recorded in the foundation stock. These results suggest that GHB-C rats may constitute a valid control line for GHB-S and GHB-R rats, representing the "general population" from which GHB-S and GHB-R rats were derived. Furthermore, the relative equidistance of sensitivity to GHB- and baclofen-induced sedation/hypnosis of GHB-C rats from those of GHB-S and GHB-R rats suggests that genetic factors contributes to the development of both sensitivity in GHB-S rats and resistance in GHB-R rats. PMID:15878144

  15. Gamma hydroxybutyrate (GHB), gamma butyrolactone (GBL) and 1,4-butanediol (1,4-BD; BDO): A literature review with a focus on UK fatalities related to non-medical use.

    PubMed

    Corkery, John M; Loi, Barbara; Claridge, Hugh; Goodair, Christine; Corazza, Ornella; Elliott, Simon; Schifano, Fabrizio

    2015-06-01

    Misuse of gamma hydroxybutrate (GHB) and gamma butyrolactone (GBL) has increased greatly since the early 1990s, being implicated in a rising number of deaths. This paper reviews knowledge on GHB and derivatives, and explores the largest series of deaths associated with their non-medical use. Descriptive analyses of cases associated with GHB/GBL and 1,4-butanediol (1,4-BD) use extracted from the UK's National Programme on Substance Abuse Deaths database. From 1995 to September 2013, 159 GHB/GBL-associated fatalities were reported. Typical victims: White (92%); young (mean age 32 years); male (82%); with a drug misuse history (70%). Most deaths (79%) were accidental or related to drug use, the remainder (potential) suicides. GHB/GBL alone was implicated in 37%; alcohol 14%; other drugs 28%; other drugs and alcohol 15%. Its endogenous nature and rapid elimination limit toxicological detection. Post-mortem blood levels: mean 482 (range 0-6500; SD 758)mg/L. Results suggest significant caution is needed when ingesting GHB/GBL, particularly with alcohol, benzodiazepines, opiates, stimulants, and ketamine. More awareness is needed about risks associated with consumption. PMID:25843781

  16. GHB Abuse Trends and Use in Drug-Facilitated Sexual Assault: Implications for Prevention.

    ERIC Educational Resources Information Center

    Hensley, Laura

    2003-01-01

    Gamma-hydroxybutyric acid (GHB) has become increasingly popular on the campuses of American colleges and universities. In this paper, the characteristics of GHB and the effects of both voluntary and involuntary abuse are described. Further, implications for prevention efforts related to involuntary GHB ingestion and GHB-facilitated rape are…

  17. Gamma hydroxybutyrate: an ethnographic study of recreational use and abuse.

    PubMed

    Lee, Steven J; Levounis, Petros

    2008-09-01

    Gamma hydroxybutyrate (GHB) is a psychoactive substance with complex neurophysiological activity and significant potential for abuse, addiction, and dangerous toxicity. In this study, a semistructured interview was administered to 17 subjects to investigate GHB use, including: manner of use; setting; positive and negative consequences; other drug history; and sexual practices. Respondents were overwhelmingly male, but otherwise had a broad demographic background. Settings varied from nightclubs to private use at home. There was significant variability in the drug obtained, which subjects found problematic because of the narrow therapeutic window and ease of accidental overdose. Common positive experiences included increased sexual desire, decreased sexual inhibitions, and decreased anxiety. Common negative consequences included oversedation, loss of consciousness, motor incoordination, and mental confusion. Nine subjects reported that they would use GHB again, some despite severe negative consequences. Although most subjects reported negative experiences, only three felt their use was problematic, and none sought treatment for GHB abuse or addiction. Subjects were highly drug-experienced, most commonly using MDMA, ketamine, cocaine, alcohol, and methamphetamine. Some reported that GHB could cause poor decision making in sexual situations. This effect has significant ramifications for issues such as date rape and control of sexually transmitted diseases, such as HIV. PMID:19004416

  18. Gamma-hydroxybutyrate enhances mood and prosocial behavior without affecting plasma oxytocin and testosterone.

    PubMed

    Bosch, Oliver G; Eisenegger, Christoph; Gertsch, Jürg; von Rotz, Robin; Dornbierer, Dario; Gachet, M Salomé; Heinrichs, Markus; Wetter, Thomas C; Seifritz, Erich; Quednow, Boris B

    2015-12-01

    Gamma-hydroxybutyrate (GHB) is a GHB-/GABAB-receptor agonist. Reports from GHB abusers indicate euphoric, prosocial, and empathogenic effects of the drug. We measured the effects of GHB on mood, prosocial behavior, social and non-social cognition and assessed potential underlying neuroendocrine mechanisms. GHB (20mg/kg) was tested in 16 healthy males, using a randomized, placebo-controlled, cross-over design. Subjective effects on mood were assessed by visual-analogue-scales and the GHB-Specific-Questionnaire. Prosocial behavior was examined by the Charity Donation Task, the Social Value Orientation test, and the Reciprocity Task. Reaction time, memory, empathy, and theory-of-mind were also tested. Blood plasma levels of GHB, oxytocin, testosterone, progesterone, dehydroepiandrosterone (DHEA), cortisol, aldosterone, and adrenocorticotropic-hormone (ACTH) were determined. GHB showed stimulating and sedating effects, and elicited euphoria, disinhibition, and enhanced vitality. In participants with low prosociality, the drug increased donations and prosocial money distributions. In contrast, social cognitive abilities such as emotion recognition, empathy, and theory-of-mind, and basal cognitive functions were not affected. GHB increased plasma progesterone, while oxytocin and testosterone, cortisol, aldosterone, DHEA, and ACTH levels remained unaffected. GHB has mood-enhancing and prosocial effects without affecting social hormones such as oxytocin and testosterone. These data suggest a potential involvement of GHB-/GABAB-receptors and progesterone in mood and prosocial behavior. PMID:26209926

  19. Concentration-effect relationships for the drug of abuse gamma-hydroxybutyric acid.

    PubMed

    Felmlee, Melanie A; Roiko, Samuel A; Morse, Bridget L; Morris, Marilyn E

    2010-06-01

    gamma-Hydroxybutyric acid (GHB) is an endogenous neurotransmitter that is abused because of its sedative/hypnotic and euphoric effects. The objectives of this study were to evaluate the concentration-effect relationships of GHB in plasma, cerebrospinal fluid (CSF), brain (whole and discrete brain regions), and brain frontal cortex extracellular fluid. This information is crucial for future studies to evaluate effects of therapeutic interventions on the toxicodynamics of GHB. GHB (200-1000 mg/kg) was administered intravenously to rats, and plasma and frontal cortex microdialysate samples were collected for up to 6 h after the dose, or plasma, CSF, and brain (whole, frontal cortex, striatum, and hippocampus) concentrations were determined at the offset of its sedative/hypnotic effect [return to righting reflex (RRR)]. GHB-induced changes in the brain neurotransmitters gamma-aminobutyric acid (GABA) and glutamate were also determined. GHB, GABA, and glutamate concentrations were measured by liquid chromatography/tandem mass spectrometry. GHB-induced sleep time significantly increased in a dose-dependent manner (20-fold increase from 200 to 1000 mg/kg). GHB concentrations in plasma (300-400 microg/ml), whole brain (70 microg/g), discrete brain regions (80-100 microg/g), and brain microdialysate (29-39 microg/ml) correlated with RRR. In contrast, CSF GHB and GABA and glutamate concentrations in discrete brain regions exhibited no relationship with RRR. Our results suggest that GHB-induced sedative/hypnotic effects are mediated directly by GHB and that at high GHB doses, GABA formation from GHB may not contribute to the observed sedative/hypnotic effect. These results support the use of a clinical GHB detoxification strategy aimed at decreasing plasma and brain GHB concentrations after GHB overdoses. PMID:20215411

  20. The involvement of gamma-hydroxybutyrate in reported sexual assaults: a systematic review.

    PubMed

    Németh, Zsófia; Kun, Bernadette; Demetrovics, Zsolt

    2010-09-01

    Over the past few years gamma-hydroxybutyrate (GHB) has generated widespread media interest as a possible 'date rape drug'. Our goal was to examine the extent to which GHB is associated with drug-facilitated sexual assaults. Literature was searched systematically and 11 studies, published between 1961 and June 30, 2009, were identified dealing specifically with the role of GHB in sexual assaults. GHB was detected in 0.2-4.4% of reported sexual assaults. The results demonstrate that a wide range of drugs may be present in cases of sexual assault, and many of them are much more frequent than GHB. Our results do not support the widespread labelling of GHB as a date rape drug as the prevalence of GHB is much lower than of other substances used in sexual assaults. On the other hand, however, the possible risk of GHB in this regard should not be neglected. Nevertheless, over-sensitive and sensation seeking media reports focusing on the association of sex crime and GHB might be counterproductive and misleading as they turn the attention away from other substances that are often used in sexual assaults. PMID:20488831

  1. GABAB receptor-mediated activation of astrocytes by gamma-hydroxybutyric acid

    PubMed Central

    Gould, Timothy; Chen, Lixin; Emri, Zsuzsa; Pirttimaki, Tiina; Errington, Adam C.; Crunelli, Vincenzo; Parri, H. Rheinallt

    2014-01-01

    The gamma-aminobutyric acid (GABA) metabolite gamma-hydroxybutyric acid (GHB) shows a variety of behavioural effects when administered to animals and humans, including reward/addiction properties and absence seizures. At the cellular level, these actions of GHB are mediated by activation of neuronal GABAB receptors (GABABRs) where it acts as a weak agonist. Because astrocytes respond to endogenous and exogenously applied GABA by activation of both GABAA and GABABRs, here we investigated the action of GHB on astrocytes on the ventral tegmental area (VTA) and the ventrobasal (VB) thalamic nucleus, two brain areas involved in the reward and proepileptic action of GHB, respectively, and compared it with that of the potent GABABR agonist baclofen. We found that GHB and baclofen elicited dose-dependent (ED50: 1.6 mM and 1.3 µM, respectively) transient increases in intracellular Ca2+ in VTA and VB astrocytes of young mice and rats, which were accounted for by activation of their GABABRs and mediated by Ca2+ release from intracellular store release. In contrast, prolonged GHB and baclofen exposure caused a reduction in spontaneous astrocyte activity and glutamate release from VTA astrocytes. These findings have key (patho)physiological implications for our understanding of the addictive and proepileptic actions of GHB. PMID:25225100

  2. GHB: Forensic examination of a dangerous recreational drug by FTIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Kindig, J. P.; Ellis, L. E.; Brueggemeyer, T. W.; Satzger, R. D.

    1998-06-01

    Gamma-hydroxybutyric acid (GHB) is an illegal drug that has been abused for its intoxicating effects. However, GHB can also produce harmful physiological effects ranging from mild (nausea, drowsiness) to severe (coma, death). Because GHB is often produced by clandestine manufacture, its concentration, purity, and final form can be variable. Therefore, the analysis of suspected GHB samples using FTIR spectroscopy requires a variety of sample preparations and accessories, based on the sample matrix.

  3. Determination of GHB and its precursors (GBL and 1,4-BD) in dietary supplements through the synthesis of their isotopologues and analysis by GC-MS method.

    PubMed

    Rosi, Luca; Frediani, Piero; Bartolucci, Gianluca

    2013-02-23

    Gamma-hydroxybutyric acid (GHB) and its "pro-drugs", gamma-butyrolactone (GBL) and 1,4 butanediol (1,4-BD), are drugs of abuse with depressant effects on the central nervous system. Many analytical methods have been proposed for the quantitative determination of these compounds mainly in biological matrices but only few have been addressed to dietary supplements and foods. Facile synthesis of the GBL and 1,4-BD isotopologues are available by "one pot" Ru-catalyzed homogeneous deuteration of dicarboxylic acids. In this work we propose a new method for determination of GHB, GBL and 1,4-BD in commercially available dietary supplements, based on isotope dilution mass spectrometry (ID-MS). The procedure involves a simple extraction of sample with acidic acetonitrile and direct analysis by GC-ID-MS method without any purification or derivatization. Indeed, the proposed method takes advantage of the complete conversion of GHB (free acid or its salts) to GBL, allowing the quantification of GHB and its pro-drugs. Five levels for each calibration curve have been prepared by diluting working solutions of the analytes to obtain concentrations ranging from 1 to 20mg/mL. The validation procedures have shown an accuracy between 88% and 99% and a precision between 7.3% and 2.9% of each analyte in the sample matrix. Positive ions chemical ionization (PICI) have been employed to preserve the information on molecular ions and to improve specificity and sensitivity of quantitative determination. PMID:23245230

  4. Mechanistic toxicokinetic model for gamma-hydroxybutyric acid: inhibition of active renal reabsorption as a potential therapeutic strategy.

    PubMed

    Felmlee, Melanie A; Wang, Qi; Cui, Dapeng; Roiko, Samuel A; Morris, Marilyn E

    2010-09-01

    gamma-Hydroxybutyric acid (GHB), a drug of abuse, exhibits saturable renal clearance and capacity-limited metabolism. The objectives of this study were to construct a mechanistic toxicokinetic (TK) model describing saturable renal reabsorption and capacity-limited metabolism of GHB and to predict the effects of inhibition of renal reabsorption on GHB TK in the plasma and urine. GHB was administered by iv bolus (200-1,000 mg/kg) to male Sprague-Dawley rats and plasma and urine samples were collected for up to 6 h post-dose. GHB concentrations were determined by LC/MS/MS. GHB plasma concentration and urinary excretion were well-described by a TK model incorporating plasma and kidney compartments, along with two tissue and two ultrafiltrate compartments. The estimate of the Michaelis-Menten constant for renal reabsorption (K (m,R)) was 0.46 mg/ml which is consistent with in vitro estimates of monocarboxylate transporter (MCT)-mediated uptake of GHB (0.48 mg/ml). Simulation studies assessing inhibition of renal reabsorption of GHB demonstrated increased time-averaged renal clearance and GHB plasma AUC, independent of the inhibition mechanism assessed. Co-administration of GHB (600 mg/kg iv) and L: -lactate (330 mg/kg iv bolus plus 121 mg/kg/h iv infusion), a known inhibitor of MCTs, resulted in a significant decrease in GHB plasma AUC and an increase in time-averaged renal clearance, consistent with the model simulations. These results suggest that inhibition of renal reabsorption of GHB is a viable therapeutic strategy for the treatment of GHB overdoses. Furthermore, the mechanistic TK model provides a useful in silico tool for the evaluation of potential therapeutic strategies. PMID:20461486

  5. Pharmacokinetic interaction between the flavonoid luteolin and gamma-hydroxybutyrate in rats: potential involvement of monocarboxylate transporters.

    PubMed

    Wang, Xiaodong; Wang, Qi; Morris, Marilyn E

    2008-01-01

    Monocarboxylate transporter 1 (MCT1) has been previously reported as an important determinant of the renal reabsorption of the drug of abuse, gamma-hydroxybutyrate (GHB). Luteolin is a potent MCT1 inhibitor, inhibiting the uptake of GHB with an IC(50) of 0.41 microM in MCT1-transfected MDA-MB231 cells. The objectives of this study were to characterize the effects of luteolin on GHB pharmacokinetics and pharmacodynamics in rats, and to investigate the mechanism of the interaction using model-fitting methods. GHB (400 and 1,000 mg/kg) and luteolin (0, 4 and 10 mg/kg) were administered to rats via iv bolus doses. The plasma or urine concentrations of luteolin and GHB were determined by HPLC and LC/MS/MS, respectively. The pharmacodynamic parameter sleep time in rats after GHB administration was recorded. A pharmacokinetic model containing capacity-limited renal reabsorption and metabolic clearance was constructed to characterize the in vivo interaction. Luteolin significantly decreased the plasma concentration and AUC, and increased the total and renal clearances of GHB. Moreover, luteolin significantly shortened the duration of GHB (1,000 mg/kg)-induced sleep in rats (161 +/- 16, 131 +/- 14 and 121 +/- 5 min for control, luteolin 4 and 10 mg/kg groups, respectively, p < 0.01). An uncompetitive inhibition model, with an inhibition constant of 1.1 microM, best described the in vivo pharmacokinetic interaction. The results of this study indicated that luteolin significantly altered the pharmacokinetics of GHB by inhibiting its MCT1-mediated transport. The interaction between luteolin and GHB may offer a potential clinical detoxification strategy to treat GHB overdoses. PMID:18446505

  6. Potential surrogate markers for gamma-hydroxybutyrate administration may extend the detection window from 12 to 48 hours.

    PubMed

    Larson, Scott J; Putnam, Elizabeth A; Schwanke, Corbin M; Pershouse, Mark A

    2007-01-01

    The exogenous administration of gamma-hydroxybutyrate (GHB) as a drug of abuse, and especially in date rape sexual assaults, has recently increased. Chromatographic techniques are used to detect GHB in blood or urine, with a window of detection limited to 12 h. This brief window makes the proof of administration problematic in most rape cases. This study is aimed to extend the window of detection through surrogate markers of GHB administration. Microarray technology is used in a DBA/2J mouse model to detect gene expression changes in peripheral blood after GHB exposure at times as long as 96 h post exposure. This study focuses on two of the most significantly altered transcripts, epiregulin and phosphoprotein enriched in astrocytes 15 (Pea-15). Both genes have increased the ribonucleic acid expression (8.5- and 4.6-fold upregulation at 96 h, respectively) in GHB-dosed mice (1 g/kg) as compared with the control. To confirm these results at the protein level, an intracellular flow cytometric assay is developed to detect protein level changes in the peripheral blood of both these potential biomarkers after GHB exposure. These results suggest that after further development, epiregulin and Pea-15 may prove to be significant surrogate markers in the indirect detection of GHB administration. PMID:17389079

  7. Clinical applications of sodium oxybate (GHB): from narcolepsy to alcohol withdrawal syndrome.

    PubMed

    Busardò, F P; Kyriakou, C; Napoletano, S; Marinelli, E; Zaami, S

    2015-12-01

    Gamma-hydroxybutyrate (GHB) is a short chain fatty acid endogenously produced within the central nervous system (CNS) and acts as a precursor and metabolite of the inhibitory neurotransmitter γ-aminobutyric acid (GABA). Although, it is an illegal recreational drug of abuse, its sodium salt (sodium oxybate) has been utilized as a medication for a number of medical conditions. The first aim of this review was to focus on current applications of sodium oxybate for the treatment of narcolepsy, with a particular emphasis on the key symptoms of this disorder: cataplexy and excessive daytime sleepiness (EDS). Secondly, the effectiveness of sodium oxybate therapy for the treatment of alcohol withdrawal syndrome (AWS) and the maintenance of alcohol abstinence has been assessed. Nowadays, sodium oxybate is the first-line treatment for narcolepsy and it is highly effective in meliorating sleep architecture, decreasing EDS and the frequency of cataplexy attacks in narcoleptic patients. Sodium oxybate currently finds also application in the treatment of AWS and the maintenance of alcohol abstinence in alcoholics. Most of the studies evaluating the efficacy of GHB in the treatment of AWS use a dosage of 50 mg/kg divided in three or four administrations per day. Human studies showed that GHB (dose of 50 mg/kg, divided in three administrations per day) is capable to increase the number of abstinent days, reduce alcohol craving and decrease the number of drinks per day. However, there is limited randomized evidence and, thus, GHB cannot be reliably compared to clomethiazole or benzodiazepines. Some randomized data suggest that GHB is better than naltrexone and disulfiram regarding abstinence maintenance and prevention of craving in the medium term i.e. 3-12 months. It is recommended that GHB should be used only under strict medical supervision, since concerns about the abuse/misuse of the drug and the addiction potential have been arisen. PMID:26698265

  8. Flavonoids modulate monocarboxylate transporter-1-mediated transport of gamma-hydroxybutyrate in vitro and in vivo.

    PubMed

    Wang, Qi; Morris, Marilyn E

    2007-02-01

    The objective of this study was to determine the effects of flavonoids on the in vitro monocarboxylate transporter 1 (MCT1)-mediated transport and in vivo disposition of the drug of abuse, gamma-hydroxybutyrate (GHB). The uptake of GHB in rat MCT1 gene-transfected MDA-MB231 cells was significantly decreased in the presence of the flavonoids apigenin, biochanin A, chrysin, diosemin, fisetin, genistein, hesperitin, kaempferol, luteolin, morin, narigenin, phloretin, and quercetin, but was not affected by the flavonoid glycosides phloridzin and rutin. The IC(50) values for luteolin, morin, and phloretin were 0.41 +/- 0.14, 6.41 +/- 2.01, and 2.57 +/- 0.48 microM, with the inhibition mechanism for luteolin being competitive. [(3)H]Kaempferol and [(3)H]biochanin A did not exhibit MCT1-mediated uptake, suggesting that these flavonoids are not substrates for MCT1. The combination of luteolin and phloretin inhibited the uptake of GHB in a synergistic manner; however, the combination of luteolin and morin was antagonistic. GHB 1000 mg/kg was administered to rats by i.v. bolus, with or without the concomitant administration of luteolin 10 mg/kg i.v. After luteolin treatment, the renal and total clearances of GHB were significantly increased, probably because of inhibition of the MCT1-mediated renal reabsorption of GHB, and the sleep time significantly decreased (121 +/- 5 min versus 165 +/- 10 min) compared with control rats. Overall, the results of this study indicate that flavonoids from food or herbal products may significantly alter the pharmacokinetics and pharmacodynamics of MCT substrates. PMID:17108059

  9. Metabolism of gamma hydroxybutyrate in human hepatoma HepG2 cells by the aldo-keto reductase AKR1A1.

    PubMed

    Alzeer, Samar; Ellis, Elizabeth M

    2014-12-01

    Gamma hydroxybutyrate (GHB) is a recreational and date-rape drug, for which the detection following ingestion is hampered by rapid metabolism and its endogenous presence. GHB catabolism occurs mainly by its oxidation to succinic semialdehyde (SSA), which converts to succinate and enters the tricarboxylic acid cycle. A high Km aldehyde reductase has previously been reported to catalyse the NADP-dependent oxidation of GHB at high concentrations. It is assumed that this enzyme is identical to the aldo-keto reductase AKR1A1, but its role in GHB oxidation has not been fully evaluated. In this study, the extent of AKR1A1 in GHB metabolism has been determined in HepG2 cells using RNA-interference technology. The gene encoding AKR1A1 was targeted by siRNA. Results demonstrate a successful knock-down of the AKR1A1 gene with 92% reduction in total mRNA and 93% reduction in protein expression. Demolishing AKR1A1 expression in HepG2 cells leads to significant 82% decrease in NADP-dependent GHB-dehydrogenase activity at high concentration (10mM) of GHB. Moreover, when exposing the cells to 50 μM of GHB for 24h, and measuring intracellular and extracellular GHB levels by GC/MS, a significant two-fold increase was observed on GHB intracellular level in silenced cells. In contrast, measuring SSA-reductase activity in silenced cells indicated that AKR1A1 is not involved in endogenous GHB production. These findings describe a pathway for GHB metabolism in the liver which should be useful in GHB exposure cases, and will enable a better understanding of the enzymes participating in its metabolism at natural and overexposed levels. PMID:25256836

  10. Endogenous concentrations of GHB in postmortem blood from deaths unrelated to GHB use.

    PubMed

    Korb, Ann-Sophie; Cooper, Gail

    2014-10-01

    Gamma-hydroxybutyrate (GHB) is an endogenous compound, but its presence in postmortem blood presents a challenge when interpreting elevated levels as GHB is misused as a recreational drug and is also produced postmortem. A total of 387 postmortem cases (273 male and 114 female) submitted to the toxicology laboratory between 2010 and 2012 specifically requested the analysis of the ketoacidosis biomarker, beta-hydroxybutyrate (BHB). No reference to GHB use was identified in any of the case files; however, BHB and GHB are measured simultaneously using deuterated GHB as the internal standard (GHB-d6) within a calibration range of 5-500 mg/L. GHB was not detected or <10 mg/L in 18% of the cases (n = 68), between 10 and 50 mg/L in 73% of the cases (n = 283) and between 51 and 193 mg/L in 9% of the cases (n = 36). The manner of death was classified as accidental (n = 11), alcohol-related (n = 237), drug-related (n = 23), homicide (n = 1), natural (n = 91), suicide (n = 9), medical-related (n = 1) and undetermined (n = 14). Six cases had GHB concentrations in excess of 100 mg/L with advanced decomposition changes noted in five of these cases. Moderate-to-advanced decomposition was also noted in 50% (n = 15) of the cases with GHB concentrations in excess of 50 mg/L but <100 mg/L. Approximately one-third of the blood samples tested contained a preservative and although a higher proportion of these samples had GHB concentrations <10 mg/L or not detected (?30% preserved versus 11% unpreserved), there were still cases with GHB concentrations >51 mg/L (?6% preserved versus 11% unpreserved). This study highlights the danger of only using a cutoff to establish endogenous levels compared with exogenous use of GHB in postmortem blood. PMID:25217550

  11. What is the role of the gamma-hydroxybutyrate receptor?

    PubMed

    Cash, C D

    1996-12-01

    A possible functional role for endogenous gamma-hydroxybutyrate has been disputed. However, there are receptor sites for this molecule, which are highly enriched in the synaptosomal membrane fraction in the rat brain and are functionally linked to a guanosine triphosphate-binding protein. These data suggest that they play a neurological role. The binding sites recognize some drug molecules that bear no structural similarity to gamma-hydroxybutyrate. Recent experimental evidence indicates the existence of endogenous hydrophobic ligands. As a minor brain metabolite directly or indirectly involved in scavenging oxygen-derived free radicals, gamma-hydroxybutyrate demonstrates similarities with melatonin. The gamma-hydroxybutyrate receptor is compared to the cannabis receptor, for which an endogenous hydrophobic ligand has been identified. Structurally similar molecules to this ligand are believed to be implicated in the sleep process. As gamma-hydroxybutyrate itself can induce sleep, a search amongst these molecules as possible ligands for the gamma-hydroxybutyrate receptor might be enlightening. PMID:8961242

  12. Gamma-hydroxybutyrate withdrawal syndrome: a case report

    PubMed Central

    2009-01-01

    Introduction To raise awareness among health care workers of the risk of withdrawal symptoms after longstanding and intense abuse of gamma-hydroxybutyric acid. Case presentation A 23 year old Caucasian woman presented with gamma-hydroxybutyric addiction and withdrawal syndrome. The symptoms of gamma-hydroxybutyric withdrawal in this patient initially went unrecognized, upon which her situation deteriorated in such a way that she needed to be admitted to the Intensive Care Unit for airway protection and mechanical ventilation. Treatment with high doses of benzodiazepines led to liberation of the ventilator and further recovery. Conclusion Withdrawal symptoms of gamma-hydroxybutyric addiction are often not well recognized and the responsible physicians at Emergency Department, Intensive Care Unit and the Psychiatry ward need better understanding of diagnose and treatment. Gamma-hydroxybutyric acid withdrawal is potentially life threatening and its management may require a multidisciplinary approach. Early recognition of gamma-hydroxybutyric acid withdrawal may lead to better management of these patients. PMID:20181164

  13. Do capillary dried blood spot concentrations of gamma-hydroxybutyric acid mirror those in venous blood? A comparative study.

    PubMed

    Sadones, Nele; Archer, John R H; Ingels, Ann-Sofie M E; Dargan, Paul I; Wood, David M; Wood, Michelle; Neels, Hugo; Lambert, Willy E; Stove, Christophe P

    2015-04-01

    Gamma-hydroxybutyric acid (GHB) is a well-known illicit club and date-rape drug. Dried blood spot (DBS) sampling is a promising alternative for classical venous sampling in cases of (suspected) GHB intoxication since it allows rapid sampling, which is of interest for the extensively metabolized GHB. However, there is limited data if -and how- capillary DBS concentrations correlate with venous concentrations. We conducted a comparative study in 50 patients with suspected GHB intoxication, to determine and to correlate GHB concentrations in venous DBS (vDBS) and capillary DBS (cDBS). This is the first study that evaluates in a large cohort the correlation between capillary and venous concentrations of an illicit drug in real-life samples. Of the 50 paired samples, 7 were excluded: the vDBS concentration was below the LLOQ of 2 µg/mL in 3 cases and 4 samples were excluded after visual inspection of the DBS. Bland-Altman analysis revealed a mean % difference of -2.8% between cDBS and vDBS concentrations, with the zero value included in the 95% confidence interval of the mean difference in GHB concentration. A paired sample t-test confirmed this observation (p = 0.17). Also the requirement for incurred sample reproducibility was fulfilled: for more than two-thirds of the samples the concentrations obtained in cDBS and those in vDBS were within 20% of their mean. Since equivalent concentrations were observed in cDBS and vDBS, blood obtained by fingerprick can be considered a valid alternative for venous blood for GHB determination. PMID:25565078

  14. Temporal differences in gamma-hydroxybutyrate overdoses involving injecting drug users versus recreational drug users in Helsinki: a retrospective study

    PubMed Central

    2012-01-01

    Background Gamma-hydroxybutyrate (GHB) and gamma-butyrolactone (GBL) have been profiled as 'party drugs' used mainly at dance parties and in nightclubs on weekend nights. The purpose of this study was to examine the frequency of injecting drug use among GHB/GBL overdose patients and whether there are temporal differences in the occurrence of GHB/GBL overdoses of injecting drug and recreational drug users. Methods In this retrospective study, the ambulance and hospital records of suspected GHB- and GBL overdose patients treated by the Helsinki Emergency Medical Service from January 1st 2006 to December 31st 2007 were reviewed. According to the temporal occurrence of the overdose, patients were divided in two groups. In group A, the overdose occurred on a Friday-Saturday or Saturday-Sunday night between 11 pm-6 am. Group B consisted of overdoses occurring on outside this time frame. Results Group A consisted of 39 patient contacts and the remaining 61 patient contacts were in group B. There were statistically significant differences between the two groups in (group A vs. B, respectively): history of injecting drug abuse (33% vs. 59%, p = 0.012), reported polydrug and ethanol use (80% vs. 62%, p = 0.028), the location where the patients were encountered (private or public indoors or outdoors, 10%, 41%, 41% vs. 25%, 18%, 53%, p = 0.019) and how the knowledge of GHB/GBL use was obtained (reported by patient/bystanders or clinical suspicion, 72%, 28% vs. 85%, 10%, p = 0.023). Practically all (99%) patients were transported to emergency department after prehospital care. Conclusion There appears to be at least two distinct groups of GHB/GBL users. Injecting drug users represent the majority of GHB/GBL overdose patients outside weekend nights. PMID:22296777

  15. Activation of astroglial calcium signaling by endogenous metabolites succinate and gamma-hydroxybutyrate in the nucleus accumbens.

    PubMed

    Molnár, Tünde; Héja, László; Emri, Zsuzsa; Simon, Agnes; Nyitrai, Gabriella; Pál, Ildikó; Kardos, Julianna

    2011-01-01

    Accumulating evidence suggests that different energy metabolites play a role not only in neuronal but also in glial signaling. Recently, astroglial Ca(2+) transients evoked by the major citric acid cycle metabolite succinate (SUC) and gamma-hydroxybutyrate (GHB) that enters the citric acid cycle via SUC have been described in the brain reward area, the nucleus accumbens (NAc). Cells responding to SUC by Ca(2+) transient constitute a subset of ATP-responsive astrocytes that are activated in a neuron-independent way. In this study we show that GHB-evoked Ca(2+) transients were also found to constitute a subset of ATP-responsive astrocytes in the NAc. Repetitive Ca(2+) dynamics evoked by GHB suggested that Ca(2+) was released from internal stores. Similarly to SUC, the GHB response was also characterized by an effective concentration of 50 μM. We observed that the number of ATP-responsive cells decreased with increasing concentration of either SUC or GHB. Moreover, the concentration dependence of the number of ATP-responsive cells were highly identical as a function of both [SUC] and [GHB], suggesting a mutual receptor for SUC and GHB, therefore implying the existence of a distinct GHB-recognizing astroglial SUC receptor in the brain. The SUC-evoked Ca(2+) signal remained in mice lacking GABA(B) receptor type 1 subunit in the presence and absence of the N-Methyl-d-Aspartate (NMDA) receptor antagonist (2R)-amino-5-phosphonovaleric acid (APV), indicating action mechanisms independent of the GABA(B) or NMDA receptor subtypes. By molecular docking calculations we found that residues R99, H103, R252, and R281 of the binding crevice of the kidney SUC-responsive membrane receptor SUCNR1 (GPCR91) also predict interaction with GHB, further implying similar GHB and SUC action mechanisms. We conclude that the astroglial action of SUC and GHB may represent a link between brain energy states and Ca(2+) signaling in astrocytic networks. PMID:22180742

  16. Effect of gamma-hydroxybutyrate on keratinocytes proliferation: A preliminary prospective controlled study in severe burn patients

    PubMed Central

    Rousseau, Anne-Françoise; Bargues, Laurent; Bever, Hervé Le; Vest, Philippe; Cavalier, Etienne; Ledoux, Didier; Piérard, Gérald E.; Damas, Pierre

    2014-01-01

    Background: Hypermetabolism and hyposomatotropism related to severe burns lead to impaired wound healing. Growth hormone (GH) boosts wound healing notably following stimulation of the production of insulin-like growth factor-1 (IGF1), a mitogen factor for keratinocytes. Gamma-hydroxybutyrate (GHB) stimulates endogenous GH secretion. Aim: To assess effects of GHB sedation on keratinocytes proliferation (based on immunohistochemical techniques). Design: Monocentric, prospective, controlled trial. Materials and Methods: Patients (aging 18-65 years, burn surface area >30%, expected to be sedated for at least one month) were alternately allocated, at the 5th day following injury, in three groups according to the intravenous GHB dose administered for 21 days: Evening bolus of 50 mg/kg (Group B), continuous infusion at the rate of 10 mg/kg/h (Group C), or absence of GHB (Group P). They all received local standard cares. Immunohistochemistry (Ki67/MIB-1, Ulex europaeus agglutinin-1 and Mac 387 antibodies) was performed at D21 on adjacent unburned skin sample for assessing any keratinocyte activation. Serum IGF1 levels were measured at initiation and completion of the protocol. Statistical Analysis: Categorical variables were compared with Chi-square test. Comparisons of medians were made using Kruskal-Wallis test. Post hoc analyses were performed using Mann-Whitney test with Bonferroni correction for multiple comparisons. A P < 0.05 was considered to be statistically significant. Results: A total of 14 patients completed the study (Group B: n = 5, Group C: n = 5, Group P: n = 4). Continuous administration of GHB was associated with a significant higher Ki67 immunolabeling at D21 (P = 0.049) and with a significant higher increase in the IGF1 concentrations at D21 (P = 0.024). No adverse effects were disclosed. Conclusions: Our preliminary data support a positive effect of GHB on keratinocyte proliferation and are encouraging enough to warrant large prospective studies. PMID:25024938

  17. An open randomized study of the treatment of escitalopram alone and combined with gamma-hydroxybutyric acid and naltrexone in alcoholic patients.

    PubMed

    Stella, Luigi; Addolorato, Giovanni; Rinaldi, Barbara; Capuano, Annalisa; Berrino, Liberato; Rossi, Francesca; Maione, Sabatino

    2008-04-01

    gamma-hydroxybutyric acid (GHB) and the selective serotonin reuptake inhibitor escitalopram are effective in inducing and maintaining abstinence in alcohol. Naltrexone (NTX), an opioid antagonist, may be effective in preventing relapse in alcohol-dependent subjects. To evaluate whether each drug and its combination help to maintain alcohol abstinence, we determined the relapse rate over 6 months in 3 groups of patients. Group 1 (11 patients) received escitalopram (20 mg/day) orally administered; group 2 (12 patients) received NTX (50 mg/day) and escitalopram (20 mg/day); group 3 (12 patients) received GHB (75 mg/kg body weight) and escitalopram (20 mg/day); and group 4 (12 patients) received NTX (50mg/day) plus GHB (75 mg/kg) and escitalopram (20 mg/day). All groups received psychological support and underwent urine tests for alcohol metabolites twice a week. In group 1 (escitalopram only), 6 patients relapsed within 3 months and 3 after 6 months; whereas 2 patients remained abstinent. In group 2 (SSRI+NTX), 5 patients relapsed after 3 months and 3 after 6 months; whereas 4 patients remained abstinent. In group 3 (GHB+SSRI), 3 patients relapsed after 3 months and 3 after 6 months; whereas 6 patients remained abstinent. Finally, in group 4 (NTX+GHB+SSRI), 1 patient relapsed after 3 months and 1 after 6 months, whereas 10 patients remain abstinent. In conclusion, the combination of NTX+GHB+SSRI was the most effective in preventing relapses. PMID:18434189

  18. GHB acid: A rage or reprive

    PubMed Central

    Kapoor, Prakhar; Deshmukh, Revati; Kukreja, Ipsita

    2013-01-01

    Gamma-hydroxybutyric acid (GHB) is a naturally occurring analog of gamma-aminobutyric acid (GABA) that has been used in research and clinical medicine for many years. GHB was used clinically as an anesthetic in the 1960s but was withdrawn due to side effects that included seizures and coma. GHB has been implicated in a number of crime types; most notably in drug-facilitated sexual assault. GHB is abused by three main groups of users: Body builders who use the substance believing that it stimulated the release of growth hormone; sexual predators who covertly administer the drug for its sedative and amnesic effects and club-goers (rave parties) who take the drug for its euphoric effects. The short-lived hypnotic effects, relative safety and widespread availability of the drug have made it particularly well suited to this role. The drug has an addictive potential if used for long term. The primary effects of GHB use are those of a CNS depressant and therefore range from relaxation, to euphoria, confusion, amnesia, hallucinations, and coma. Despite the increased regulation, GHB remains widely available through the Internet where one can easily purchase the necessary reagents as well as recipes for home production. There are reports of patients being unresponsive to painful stimuli and cases of oral self-mutilations linked to the abuse of GHB, though quiet rare. Such cases should remind odontologists that intra-oral lesions may be the result of self-mutilation either due to mental illness or altered states caused by the use of prescription or non-prescription drugs. PMID:24350046

  19. Intoxication of a Young Girl Reveals the Pitfalls of GHB Rapid Screening.

    PubMed

    Franken, Linda G; Andrews, Louise M; Slooff, Valerie D; de Wildt, Saskia N; Koch, Birgit C P

    2016-02-01

    The authors discuss the case of a 14-year-old girl who was transferred to the ICU of our hospital with ethanol intoxication (3.3 g/L), loss of consciousness (E5M3V1), and severe amnesia on recovery that was suspected of gamma-hydroxybutyric acid (GHB) intoxication. STAT toxicology screening may be necessary, when sexual assault under GHB intoxication is suspected. Therefore, the initial analysis of a urine sample was performed with a new enzymatic assay analysis for GHB. The enzymatic assay reported a GHB concentration of 26 mg/L, which is above the cut-off value of 10 mg/L. This cut-off value is to differentiate endogenous and exogenous levels because low levels of GHB occur naturally in the body. However, confirmation of these results by gas chromatography, which is common practice to confirm a positive GHB, gave a negative result. This discrepancy is probably contributed to interference of ethanol with the assay. This is a substantial downside of the GHB rapid screening, since the combination of GHB and ethanol is common. It is therefore advised to confirm that the positive GHB results are lower than 50 mg/L by gas chromatography, when using the rapid screening. This way the false-positive results and consequent inappropriate social and legal actions may be avoided. PMID:26327308

  20. Comparative abuse liability of GHB and ethanol in humans

    PubMed Central

    Johnson, Matthew W.; Griffiths, Roland R.

    2013-01-01

    Gamma-hydroxybutyric acid (GHB; sodium oxybate) is approved for narcolepsy symptom treatment, and it is also abused. This study compared the participant-rated, observer-rated effects, motor/cognitive, physiological, and reinforcing effects of GHB and ethanol in participants with histories of sedative (including alcohol) abuse. Fourteen participants lived on a residential unit for ~1 month. Sessions were conducted Monday through Friday. Measures were taken before, and repeatedly up to 24 hours after drug administration. Participants were administered GHB (1, 2, 4, 6, 8, and 10 g/70kg), ethanol (12, 24, 48, 72, 96, and 120 g/70kg), or placebo in a double-blind, within-subjects design. For safety, GHB and ethanol were administered in an ascending dose sequence, with placebos and both drugs intermixed across sessions. The sequence for each drug was stopped if significant impairment or intolerable effects occurred. Only 9 and 10 participants received the full dose range for GHB and ethanol, respectively. The highest doses of GHB and ethanol showed onset within 30 minutes, with peak effects at 60 minutes. GHB effects dissipated between 4 and 6 hours, while ethanol effects dissipated between 6 and 8 hours. Dose-related effects were observed for both drugs on a variety of measures assessing sedative drug effects, abuse liability, performance impairment, and physiological effects. Within-session measures of abuse liability were similar between the two drugs. However, post-session measures of abuse liability, including a direct preference test between the highest tolerated doses of each drug, suggested somewhat greater abuse liability for GHB, due most likely to the delayed aversive ethanol effects (e.g., headache). PMID:23421353

  1. Gamma-hydroxybutyrate and cocaine intoxication in a Danish child.

    PubMed

    de Knegt, Victoria Elizabeth; Breindahl, Torben; Harboe, Kirstine Moll; Møller, Gitte Leth; Børresen, Malene Landbo

    2016-03-01

    GHB intoxication must be considered in children with coma and a suspicion of drug intoxication. Furthermore, mixed intoxication with several substances and the possibility of unpredictable symptom profiles should be anticipated to ensure optimal symptomatic treatment of patients. PMID:27014439

  2. An improved method for the analysis of GHB in human hair by liquid chromatography tandem mass spectrometry.

    PubMed

    Jagerdeo, Eshwar; Montgomery, Madeline A; LeBeau, Marc A

    2015-03-01

    The abuse of gamma-hydroxybutyric acid (GHB) and its suspicion in cases of suspected drug-facilitated sexual assault is of keen interest to forensic toxicology laboratories. This paper reports an extraction, separation and detection procedure for GHB in hair utilizing a combination of liquid-liquid extraction and solid-phase extraction using ethyl acetate and Oasis Max(®) cartridge, respectively, after the hair sample was digested. Analysis was by LC-MS-MS using a gradient separation on an Acclaim(®) Trinity(TM) P1 column performing three multiple-reaction monitoring (MRM) transitions each for GHB and its internal standard. The procedure was validated over a range from 0.4 to 50 ng/mg with estimated limit of detection (LOD) of 0.33 and an administratively set limit of quantitation (LOQ) of 1.2 ng/mg. Twenty hair specimens collected from individuals with no known exposure to GHB were analyzed for matrix interferences and to establish initial background levels of GHB. A wide range of endogenous GHB levels were observed in these samples (from less than the LOQ to 4.4 ng/mg). The results suggest the need for additional studies to better establish the full range of endogenous GHB levels in hair and that extreme caution is required in interpreting GHB findings in hair samples. PMID:25433016

  3. Gamma-hydroxybutyric acid endogenous production and post-mortem behaviour - the importance of different biological matrices, cut-off reference values, sample collection and storage conditions.

    PubMed

    Castro, André L; Dias, Mário; Reis, Flávio; Teixeira, Helena M

    2014-10-01

    Gamma-Hydroxybutyric Acid (GHB) is an endogenous compound with a story of clinical use, since the 1960's. However, due to its secondary effects, it has become a controlled substance, entering the illicit market for recreational and "dance club scene" use, muscle enhancement purposes and drug-facilitated sexual assaults. Its endogenous context can bring some difficulties when interpreting, in a forensic context, the analytical values achieved in biological samples. This manuscript reviewed several crucial aspects related to GHB forensic toxicology evaluation, such as its post-mortem behaviour in biological samples; endogenous production values, whether in in vivo and in post-mortem samples; sampling and storage conditions (including stability tests); and cut-off reference values evaluation for different biological samples, such as whole blood, plasma, serum, urine, saliva, bile, vitreous humour and hair. This revision highlights the need of specific sampling care, storage conditions, and cut-off reference values interpretation in different biological samples, essential for proper practical application in forensic toxicology. PMID:25287794

  4. GC-MS Analysis of [gamma]-Hydroxybutyric Acid Analogs: A Forensic Chemistry Experiment

    ERIC Educational Resources Information Center

    Henck, Colin; Nally, Luke

    2007-01-01

    An upper-division forensic chemistry experiment is described. It involves using glycolic acid and sodium glycolate as analogs of [gamma]-hydroxybutyric acid and its sodium salt. The experiment shows the use of silylation in GC-MS analysis and gives students the opportunity to work with a commonly used silylating reagent,…

  5. The drug of abuse gamma-hydroxybutyrate is a substrate for sodium-coupled monocarboxylate transporter (SMCT) 1 (SLC5A8): characterization of SMCT-mediated uptake and inhibition.

    PubMed

    Cui, Dapeng; Morris, Marilyn E

    2009-07-01

    Gamma-hydroxybutyric acid (GHB), a drug of abuse, is a substrate of monocarboxylate transporters (MCTs). Sodium-coupled monocarboxylate transporter 1 (SMCT1; SLC5A8) is expressed in kidney, thyroid gland, neurons, and intestinal tract and exhibits substrate specificity similar to that of the proton-dependent MCT (SLC16A) family. The role of SMCT1 in GHB disposition has not been determined. In this study we characterized the driving force, transport kinetics, and inhibitors of GHB uptake, as well as expression of SMCT and MCT isoforms, in rat thyroid follicular (FRTL-5) cells. GHB, as well as the monocarboxylates butyrate and d-lactate, exhibited sodium-dependent uptake at pH 7.4, which could be described with a simple Michaelis-Menten equation plus a diffusional component [K(m) 0.68 +/- 0.30 mM, V(max) 3.50 +/- 1.58 nmol . mg(-1) . min(-1), and diffusional clearance (P) 0.25 +/- 0.08 microl . mg(-1) . min(-1)]. In the absence of sodium, GHB uptake was significantly increased at lower pH, suggesting proton-gradient dependent transport. Reverse transcriptase-polymerase chain reaction and Western analyses demonstrated the expression of SMCT1, MCT1, and MCT2 in FRTL-5 cells, supporting the activity results. Sodium-dependent GHB uptake in FRTL-5 cells was inhibited by MCT substrates (d-lactate, l-lactate, pyruvate, and butyrate), nonsteroidal anti-inflammatory drugs (ibuprofen, ketoprofen, and naproxen), and probenecid. IC(50) values for l-lactate, ibuprofen, ketoprofen, and probenecid were 101, 31.6, 64.4, and 380 muM, respectively. All four inhibitors also significantly inhibited GHB uptake in rat MCT1 gene-transfected MDA/MB231 cells, suggesting they are not specific for SMCT1. Luteolin and alpha-cyano-4-hydroxycinnimate represent specific proton-dependent MCT inhibitors. Our findings indicate that GHB is a substrate for both sodium- and proton-dependent MCTs and identified specific inhibitors of MCTs. PMID:19389857

  6. Identification of GHB and morphine in hair in a case of drug-facilitated sexual assault.

    PubMed

    Rossi, Riccardo; Lancia, Massimo; Gambelunghe, Cristiana; Oliva, Antonio; Fucci, Nadia

    2009-04-15

    The authors present the case of a 24-year-old girl who was sexually assaulted after administration of gamma-hydroxybutyrate (GHB) and morphine. She had been living in an international college for foreign students for about 1 year and often complained of a general unhealthy feeling in the morning. At the end of the college period she returned to Italy and received at home some video clips shot by a mobile phone camera. In these videos she was having sex with a boy she met when she was studying abroad. Toxicological analysis of her hair was done: the hair was 20-cm long. A 2/3-cm segmentation of all the length of the hair was performed. Morphine and GHB were detected in hair segments related to the period of time she was abroad. The analyses of hair segments were performed by gas chromatography/mass spectrometry (GC/MS) and the concentration of morphine and GHB were calculated. A higher value of GHB was found in the period associated with the possible criminal activity and was also associated with the presence of morphine in the same period. PMID:19261401

  7. New "lethal highs": a case of a deadly cocktail of GHB and Mephedrone.

    PubMed

    Aromatario, Mariarosaria; Bottoni, Edoardo; Santoni, Mariangela; Ciallella, Costantino

    2012-11-30

    Drug scenes within several countries have changed in recent years to incorporate a range of licit psychoactive products collectively known as "legal highs": these in combination with substances already in use can cause major health problems and even death. Consumption of Gamma-hydroxybutyric acid (GHB) spread from 1980s to 2000s, when several nations have enacted laws that have made it illegal. Cases of GHB-caused or related deaths are often described in association with alcohol or traditional drugs (heroin, cocaine, amphetamine); few cases of acute lethal toxicity due to Mephedrone have been recently reported; we describe the first case of fatality due to concomitant consumption of GHB and Mephedrone. A 43 years old man died during a drugs-based party: the two substances were not detected at toxicological screening, but were identified by further analysis on the basis of circumstantial data reported by a survivor. Through our work we aim to bring to the attention in the emerging role of new drugs of abuse, and highlight problems in identifying these drugs with immunoassay screening test commonly used. PMID:23088826

  8. Preliminary Web-Based Measures Development for GHB: Expectancies, Functions, and Withdrawal

    PubMed Central

    Stein, L.A.R.; Lebeau, Rebecca; Clair, Mary; Martin, Rosemarie; Bryant, Monte; Storti, Susan

    2015-01-01

    Background Much of what is understood regarding gamma hydroxybutyrate (GHB) treatment is based on hospital case studies for overdose and withdrawal, and there are currently no measures developed specifically for GHB or its analogs (e.g., gamma butyrolactone and 1,4-butanediol) to assess drug effect expectancies, reasons for starting use, withdrawal effects, and knowledge and opinions about use. Objectives This pilot study (N = 61) was conducted to begin measures development to assess experiences, functions of use, and opinions regarding use as indicated by respondents taking a Web-based survey. Methods Minimum average partial correlation and parallel analysis procedures are employed to create scales. Results Scales were developed to assess expectancies, reasons for use, withdrawal, and knowledge/opinions of use with median α = .79 and that account for 8.69–24.17% of the variance. Conclusion Scales have relatively good psychometric properties and replication is needed. Scientific Significance GHB-specific measures may greatly assist in furthering our understanding of protective and risk factors for use, and withdrawal phenomena. PMID:22175869

  9. Dilated cardiomyopathy and acute liver injury associated with combined use of ephedra, gamma-hydroxybutyrate, and anabolic steroids.

    PubMed

    Clark, Brychan M; Schofield, Richard S

    2005-05-01

    Anabolic-androgenic steroids are synthetic derivatives of testosterone that some athletes have used to enhance muscle mass and improve their athletic performance. Ephedrine is a potent sympathomimetic agent that can lead to cardiomyopathy similar to that seen with catecholamine excess. Adverse cardiovascular events attributed to anabolic steroid and ephedra use, such as arrhythmias, myocardial infarction, cardiomyopathy, and sudden death, are rarely reported. Bodybuilders have used gamma-hydroxybutyrate, a potent secretagogue of growth hormone, to promote muscle development. Although dilated cardiomyopathy is a known complication of excess growth hormone levels, it has not been associated with use of gamma-hydroxybutyrate. A healthy 40-year-old man was admitted to our hospital for new-onset congestive heart failure and severe acute hepatitis that developed several months after he began using anabolic-androgenic steroids, ephedra, and gamma-hydroxybutyrate supplements. Analysis with an objective causality assessment scale revealed a probable adverse drug reaction between the patient's use of anabolic steroids, ephedra, and gamma-hydroxybutyrate and the development of his cardiomyopathy and acute liver injury. PMID:15899737

  10. [The knowledge about gamma-hydroxybutyric acid as by students of Physical Education Academy].

    PubMed

    Chwaluk, Paweł; Chwaluk, Agnieszka; Parnicki, Florian

    2009-01-01

    Gamma-hydroxybutyric acid is a substance stealthily used by criminals to facilitate sexual assaults. It is also known as doping agent in sports. Physical Education Academies should prepare their graduates to be educators for young people, their trainers, organizers of sports and recreational events. Second year students of two majors: physical education and tourism and recreation were surveyed by means of questionnaire on "date-rape drug". As much as 320 among 327 students surveyed had heard about "date-rape drug". However their knowledge on it was shallow and unsystematic. None of the surveyed knew that the substance of "date-rape drug" could also be used as a doping agent. Only 31% of respondents were aware of existence of the test to detect "date-rape drug" in drinks. Physical Education Academy students should be thoroughly and relevantly educated on the matter of pharmacologic doping agents and drugs endangerment. PMID:19788135

  11. Novel homodimeric and heterodimeric rat gamma-hydroxybutyrate synthases that associate with the Golgi apparatus define a distinct subclass of aldo-keto reductase 7 family proteins.

    PubMed Central

    Kelly, Vincent P; Sherratt, Philip J; Crouch, Dorothy H; Hayes, John D

    2002-01-01

    The aldo-keto reductase (AKR) 7 family is composed of the dimeric aflatoxin B(1) aldehyde reductase (AFAR) isoenzymes. In the rat, two AFAR subunits exist, designated rAFAR1 and rAFAR2. Herein, we report the molecular cloning of rAFAR2, showing that it shares 76% sequence identity with rAFAR1. By contrast with rAFAR1, which comprises 327 amino acids, rAFAR2 contains 367 amino acids. The 40 extra residues in rAFAR2 are located at the N-terminus of the polypeptide as an Arg-rich domain that may form an amphipathic alpha-helical structure. Protein purification and Western blotting have shown that the two AFAR subunits are found in rat liver extracts as both homodimers and as a heterodimer. Reductase activity in rat liver towards 2-carboxybenzaldehyde (CBA) was resolved by anion-exchange chromatography into three peaks containing rAFAR1-1, rAFAR1-2 and rAFAR2-2 dimers. These isoenzymes are functionally distinct; with NADPH as cofactor, rAFAR1-1 has a low K(m) and high activity with CBA, whereas rAFAR2-2 exhibits a low K(m) and high activity towards succinic semialdehyde. These data suggest that rAFAR1-1 is a detoxication enzyme, while rAFAR2-2 serves to synthesize the endogenous neuromodulator gamma-hydroxybutyrate (GHB). Subcellular fractionation of liver extracts showed that rAFAR1-1 was recovered in the cytosol whereas rAFAR2-2 was associated with the Golgi apparatus. The distinct subcellular localization of the rAFAR1 and rAFAR2 subunits was confirmed by immunocytochemistry in H4IIE cells. Association of rAFAR2-2 with the Golgi apparatus presumably facilitates secretion of GHB, and the novel N-terminal domain may either determine the targeting of the enzyme to the Golgi or regulate the secretory process. A murine AKR protein of 367 residues has been identified in expressed sequence tag databases that shares 91% sequence identity with rAFAR2 and contains the Arg-rich extended N-terminus of 40 amino acids. Further bioinformatic evidence is presented that full-length human AKR7A2 is composed of 359 amino acids and also possesses an additional N-terminal domain. On the basis of these observations, we conclude that AKR7 proteins can be divided into two subfamilies, one of which is a Golgi-associated GHB synthase with a unique, previously unrecognized, N-terminal domain that is absent from other AKR proteins. PMID:12071861

  12. Baclofen and γ-hydroxybutyrate (GHB), a dangerous combination.

    PubMed

    Kamal, Rama M; Qurishi, Rouhollah; De Jong, Cornelis A J

    2015-01-01

    Baclofen is a γ-aminobutyric acid (GABA)-β receptor agonist with a muscle relaxant effect. It increases GABA activity and reduces the production of glutamate and dopamine. The GABA precursor γ-hydroxybutyrate (GHB) has gained popularity as a drug of abuse. For the first time, we report a case of a GHB-dependent patient, who ingested several days' doses of baclofen (80 mg) simultaneously with 0.3 L (215 g) of illicit GHB. Baclofen (40 mg/d) was prescribed to prevent relapse after a successful detoxification. The patient developed a rapid coma (E2M5V1 with oxygen support), bradypnea, and hypotonia. Physicians should be alert to the danger of this combination because of the hazards of coma and respiratory distress. PMID:25494007

  13. Quantitative analysis of the endogenous GHB level in the hair of the Chinese population using GC/MS/MS.

    PubMed

    Shi, Yan; Cui, Xiaopei; Shen, Min; Xiang, Ping

    2016-04-01

    Endogenous production complicates interpretation when gamma-hydroxybutyrate (GHB) is measured in hair for forensic purposes. A method capable of quantifying the endogenous concentration of GHB in human head hair was developed and validated using GC/MS/MS. Hair was digested under alkaline conditions (1 mol/L NaOH, 90 °C 10 min), and GHB-d6 was used as an internal standard. Before derivatization with BSTFA and ethyl acetate, a liquid-liquid extraction with ethyl acetate under acidic conditions was performed. GHB-TMS derivatives were detected using GC/MS/MS in the multiple-reaction monitoring mode. This method exhibited good linearity (y = 0.018x + 0.038, R(2) = 0.9998), and the limit of detection was 0.02 ng/mg. The extraction recoveries were more than 60%, and the inter-day and intra-day relative standard deviations (RSD) were less than 15%. This method has been applied for the analysis of the endogenous GHB in hair samples from 66 drug-free Chinese donors. The mean measured concentration for 0-3 cm hair was 1.93 ± 1.40 ng/mg (n = 66), and extreme values were in the range of 0.28-4.91 ng/mg. The mean male endogenous GHB level was 2.95 ng/mg (0.92-4.91 ng/mg, n = 35), while the mean female level was 0.77 ng/mg (0.28-1.95 ng/mg, n = 31). This method was applied to a forensic case for the determination of GHB in hair samples but it is hard to make a reasonable "cut off" in hair. The solution is to use each subject as his own control. PMID:26807994

  14. Regional Fos-expression induced by ?-hydroxybutyrate (GHB): comparison with ?-butyrolactone (GBL) and effects of co-administration of the GABAB antagonist SCH 50911 and putative GHB antagonist NCS-382.

    PubMed

    van Nieuwenhuijzen, P S; McGregor, I S; Chebib, M; Hunt, G E

    2014-09-26

    ?-Hydroxybutyrate (GHB) has a complex array of neural actions that include effects on its own high-affinity GHB receptor, the release of neuroactive steroids, and agonist actions at GABAA and GABAB receptors. We previously reported partial overlap in the c-Fos expression patterns produced by GHB and the GABAB agonist, baclofen in rats. The present study extends these earlier findings by examining the extent to which GHB Fos expression and behavioral sedation are prevented by (2S)-(+)-5,5-dimethyl-2-morpholineacetic acid (SCH 50911), a GABAB antagonist, and NCS-382, a putative antagonist at the high-affinity GHB receptor. We also compare Fos expression caused by GHB and its precursor ?-butyrolactone (GBL), which is a pro-drug for GHB but lacks the high sodium content of the parent GHB molecule. Both GHB (1,000 mg/kg) and GBL (600 mg/kg) induced rapid sedation in rats that lasted over 90 min and caused similar Fos expression patterns, albeit with GBL causing greater activation of the nucleus accumbens (core and shell) and dentate gyrus (granular layer). Pretreatment with SCH 50911 (100mg/kg) partly reversed the sedative effects of GHB and significantly reduced GHB-induced Fos expression in only four regions: the tenia tecta, lateral habenula, dorsal raphe and laterodorsal tegmental nucleus. NCS-382 (50mg/kg) had no effect on GHB-induced sedation or Fos expression. When given alone, both NCS-382 and SCH 50911 increased Fos expression in the bed nucleus of the stria terminalis, central amygdala, parasubthalamic nucleus and nucleus of the solitary tract. SCH 50911 alone affected the Islands of Calleja and the medial, central and paraventricular thalamic nuclei. Overall, this study shows a surprising lack of reversal of GHB-induced Fos expression by two relevant antagonists, both of which have marked intrinsic actions. This may reflect the limited doses tested but also suggests that GHB Fos expression reflects mechanisms independent of GHB and GABAB receptors. PMID:25088910

  15. Behavioral Analyses of GHB: Receptor Mechanisms

    PubMed Central

    Carter, Lawrence P.; Koek, Wouter; France, Charles P.

    2009-01-01

    GHB is used therapeutically and recreationally, although the precise mechanism of action responsible for its different behavioral effects is not entirely clear. The purpose of this review is to summarize how behavioral procedures, especially drug discrimination procedures, have been used to study the mechanism of action of GHB. More specifically, we will review several different drug discrimination procedures and discuss how they have been used to qualitatively and quantitatively study different components of the complex mechanism of action of GHB. A growing number of studies have provided evidence that the behavioral effects of GHB are mediated predominantly by GABAB receptors. However, there is also evidence that the mechanisms mediating the effects of GHB and the prototypical GABAB receptor agonist baclofen are not identical, and that other mechanisms such as GHB receptors and subtypes of GABAA and GABAB receptors might contribute to the effects of GHB. These findings are consistent with the different behavioral profile, abuse liability, and therapeutic indications of GHB and baclofen. A better understanding of the similarities and differences between GHB and baclofen, as well as the pharmacological mechanisms of action underlying the recreational and therapeutic effects of GHB, could lead to more effective medications with fewer adverse effects. PMID:19010351

  16. Determination of GHB in human hair by HPLC-MS/MS: Development and validation of a method and application to a study group and three possible single exposure cases.

    PubMed

    Bertol, Elisabetta; Mari, Francesco; Vaiano, Fabio; Romano, Guido; Zaami, Simona; Baglìo, Giovanni; Busardò, Francesco Paolo

    2015-05-01

    Gamma-hydroxybutyrate (GHB) over the last two decades has generated increased notoriety as a euphoric and disinhibiting drug of abuse in cases of drug-related sexual assault and for this reason it is considered a 'date rape' drug. The first aim of this paper was to develop and fully validate a method for the detection of GHB in human hair by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) after liquid-liquid extraction (LLE). The second aim was the application of the method to hair samples of 30 GHB-free users in order to determine the basal level. The results obtained showed no significant differences in endogenous concentrations (p = 0.556) between hair samples of the three groups (black, blonde, and dyed hair) and the age and sex of the subjects did not affect the endogenous levels. Another 12 healthy volunteers, with no previous history of GHB use, were selected and a single dose (25 mg/Kg) was orally administered to all of them and hair samples were collected before the administration of the single dose and other two samples were collected one month and two months later, respectively. The segmental analysis of the latter two samples allowed us to calculate two ratios: 4.45:1 (95% C.I. 3.52-5.63) and 3.35:1 (95% C.I. 2.14-5.18), respectively, which can be recommended as reasonable values for a positive identification of GHB intake. Finally the method was applied to three real cases where a GHB single exposure probably occurred. PMID:24947196

  17. Determination of the lipophilicity of active anticonvulsant N-substituted amides of alpha-arylalkylamine-gamma-hydroxybutyric acid.

    PubMed

    Malawska, B; Tabor, A

    1998-01-01

    The lipophilicities of fourteen anticonvulsant active N-substituted amides of alpha-arylalkylamine-gamma-hydroxybutyric acid [I-XIV] have been determined by reversed-phase thin-layer chromatography with a mixture of methanol, TRIS buffer, and acetic acid as the solvent system. The RM value of each compound decreased linearly with increasing concentration of methanol. The partition coefficients (log P) of the amides were calculated by use of the Prolog P module of the Pallas system. Comparison of RM and log P enabled clog P values to be calculated. It was found that the anticonvulsant activity of amides [I-XIV] can be explained on the basis of their lipophilicity. PMID:10073133

  18. Physical dependence on gamma-hydroxybutrate (GHB) prodrug 1,4-butanediol (1,4-BD): Time course and severity of withdrawal in baboons

    PubMed Central

    Goodwin, Amy K.; Gibson, K. Michael; Weerts, Elise M.

    2013-01-01

    Background 1,4-butanediol (1,4-BD) is a gamma-hydroxybutyrate (GHB) pro-drug, with multiple commercial uses, and a drug of abuse. Although there are case reports of a withdrawal syndrome following 1,4-BD use, no studies have evaluated the physical dependence potential of 1,4-BD and characterized the time course of withdrawal. Methods Vehicle and then 1,4-BD were administered continuously 24 h/day via intragastric catheters in male baboons (Papio anubis, n=3). Dosing was initiated at 100 mg/kg and increased by 100 mg/kg/day to 400 mg/kg. After a stabilization period, doses of 500 and then 600 mg/kg/day were each maintained for 3-4 weeks. Plasma levels of 1,4-BD and GHB were determined for each dose condition. Physical dependence was assessed via administration of a GABA-B antagonist (precipitated withdrawal test) during administration of the 600 mg/kg dose and via abrupt termination of chronic 1,4-BD administration (spontaneous withdrawal test). Outcome measures included the number of food pellets earned, performance on a fine-motor task, observed behaviors, and plasma levels of GHB and 1,4-BD. Results Following maintenance of 1,4-BD 600 mg/kg for 3 weeks, the number of food pellets earned was significantly decreased. At the end of chronic 1,4-BD dosing, the levels of GHB in plasma ranged from 1290- 2300 μmol/L and levels of 1,4-BD in plasma ranged from 13.1 -37.9 μmol/L. Signs of physical dependence were observed following precipitated and spontaneous withdrawal tests. Seizures were not observed. Conclusions These data indicate chronic 1,4-BD produced physical dependence in baboons and the withdrawal syndrome can be characterized as mild to intermediate. PMID:23538206

  19. GHB Pharmacology and Toxicology: Acute Intoxication, Concentrations in Blood and Urine in Forensic Cases and Treatment of the Withdrawal Syndrome

    PubMed Central

    Busardò, Francesco P.; Jones, Alan W.

    2015-01-01

    The illicit recreational drug of abuse, γ-hydroxybutyrate (GHB) is a potent central nervous system depressant and is often encountered during forensic investigations of living and deceased persons. The sodium salt of GHB is registered as a therapeutic agent (Xyrem®), approved in some countries for the treatment of narcolepsy-associated cataplexy and (Alcover®) is an adjuvant medication for detoxification and withdrawal in alcoholics. Trace amounts of GHB are produced endogenously (0.5-1.0 mg/L) in various tissues, including the brain, where it functions as both a precursor and a metabolite of the major inhibitory neurotransmitter γ-aminobutyric acid (GABA). Available information indicates that GHB serves as a neurotransmitter or neuromodulator in the GABAergic system, especially via binding to the GABA-B receptor subtype. Although GHB is listed as a controlled substance in many countries abuse still continues, owing to the availability of precursor drugs, γ-butyrolactone (GBL) and 1,4-butanediol (BD), which are not regulated. After ingestion both GBL and BD are rapidly converted into GHB (t½ ~1 min). The Cmax occurs after 20-40 min and GHB is then eliminated from plasma with a half-life of 30-50 min. Only about 1-5% of the dose of GHB is recoverable in urine and the window of detection is relatively short (3-10 h). This calls for expeditious sampling when evidence of drug use and/or abuse is required in forensic casework. The recreational dose of GHB is not easy to estimate and a concentration in plasma of ~100 mg/L produces euphoria and disinhibition, whereas 500 mg/L might cause death from cardiorespiratory depression. Effective antidotes to reverse the sedative and intoxicating effects of GHB do not exist. The poisoned patients require supportive care, vital signs should be monitored and the airways kept clear in case of emesis. After prolonged regular use of GHB tolerance and dependence develop and abrupt cessation of drug use leads to unpleasant withdrawal symptoms. There is no evidence-based protocol available to deal with GHB withdrawal, apart from administering benzodiazepines. PMID:26074743

  20. GHB pharmacology and toxicology: acute intoxication, concentrations in blood and urine in forensic cases and treatment of the withdrawal syndrome.

    PubMed

    Busard, Francesco P; Jones, Alan W

    2015-01-01

    The illicit recreational drug of abuse, ?-hydroxybutyrate (GHB) is a potent central nervous system depressant and is often encountered during forensic investigations of living and deceased persons. The sodium salt of GHB is registered as a therapeutic agent (Xyrem), approved in some countries for the treatment of narcolepsy-associated cataplexy and (Alcover) is an adjuvant medication for detoxification and withdrawal in alcoholics. Trace amounts of GHB are produced endogenously (0.5-1.0 mg/L) in various tissues, including the brain, where it functions as both a precursor and a metabolite of the major inhibitory neurotransmitter ?-aminobutyric acid (GABA). Available information indicates that GHB serves as a neurotransmitter or neuromodulator in the GABAergic system, especially via binding to the GABA-B receptor subtype. Although GHB is listed as a controlled substance in many countries abuse still continues, owing to the availability of precursor drugs, ?-butyrolactone (GBL) and 1,4-butanediol (BD), which are not regulated. After ingestion both GBL and BD are rapidly converted into GHB (t ~1 min). The Cmax occurs after 20-40 min and GHB is then eliminated from plasma with a half-life of 30-50 min. Only about 1-5% of the dose of GHB is recoverable in urine and the window of detection is relatively short (3-10 h). This calls for expeditious sampling when evidence of drug use and/or abuse is required in forensic casework. The recreational dose of GHB is not easy to estimate and a concentration in plasma of ~100 mg/L produces euphoria and disinhibition, whereas 500 mg/L might cause death from cardiorespiratory depression. Effective antidotes to reverse the sedative and intoxicating effects of GHB do not exist. The poisoned patients require supportive care, vital signs should be monitored and the airways kept clear in case of emesis. After prolonged regular use of GHB tolerance and dependence develop and abrupt cessation of drug use leads to unpleasant withdrawal symptoms. There is no evidence-based protocol available to deal with GHB withdrawal, apart from administering benzodiazepines. PMID:26074743

  1. 3'-5' cyclic-guanosine monophosphate increase in rat brain hippocampus after gamma-hydroxybutyrate administration. Prevention by valproate and naloxone

    SciTech Connect

    Vayer, P.; Gobaille, S.; Mandel, P.; Maitre, M.

    1987-08-03

    An increase (123%) of cyclic GMP (cGMP) was observed in the hippocampus of the rat killed by microwave irradiation 45 min after administration of 500 mg/kg el-hydroxybutyrate (GHB) IP. This increase is time and dose dependent. No modification in cyclic nucleotide content was observed in striatum and in cerebellum. As the role of GHB has been implicated in neurotransmission, the fact that this compound increases cyclic GMP accumulation in hippocampus in vivo may represent a mechanism by which the actions of GHB are mediated at the cellular level. Valproate (400 mg/kg) or naloxone (10 mg/kg) pretreatment completely abolish the cGMP increase due to GHB. A GABAergic and/or opiate phenomenon may be involved in the mechanism of GHB induced increase of cGMP. 34 references, 4 figures.

  2. Concurrent Use of Methamphetamine, MDMA, LSD, Ketamine, GHB, and Flunitrazepam among American Youths

    PubMed Central

    Wu, Li-Tzy; Schlenger, William E.; Galvin, Deborah M.

    2006-01-01

    Background The magnitude and the characteristics of the use of methamphetamine, MDMA (Ecstasy), LSD (d-lysergic acid diethylamide), ketamine, GHB (gamma-hydroxybutyrate), and flunitrazepam (Rohypnol) were examined in a probability sample of the U.S. civilian population that included multiethnic urban, suburban, and rural youths aged 16 to 23 (N = 19,084). Methods Data were drawn from the National Survey on Drug Use and Health (NSDUH). Logistic regression analyses were conducted to identify the characteristics associated with the use of each of these drugs and of multiple drugs. Results Approximately 20% of youths aged 16 to 23 reported having ever used one or more of these drugs. Less than 1% of club drug users used club drugs only, and 82% of them had ever used three or more drug classes. Females were more likely than males to report using multiple club drugs. Recent users of methamphetamine were most likely to be females and adolescents aged 16 or 17. Recent users of MDMA tended to be young adults aged 18 to 21 and residents of metropolitan areas. Most recent users of LSD were adolescents aged 16 to 19 and those in low-income families. Ketamine users were primarily employed youths. Staying in school and getting married were associated with decreased odds of club drug use. Club drug use was highly associated with the presence of criminal behaviors and recent alcohol abuse or dependence. Conclusions Adolescents are more likely than young adults to use multiple drugs. The clustering of multidrug use and alcohol use disorder is a cause of concern. PMID:16483730

  3. GHB for cataplexy: Possible mode of action.

    PubMed

    Szabadi, Elemer

    2015-06-01

    The sleep disorder narcolepsy is caused by the loss of orexinergic neurones in the lateral hypothalamus. A troublesome symptom of narcolepsy is cataplexy, the sudden loss of muscle tone in response to strong emotions. It can be alleviated by antidepressants and sodium oxybate (γ-hydroxybutyric acid (GHB)). It is likely that the noradrenergic nucleus locus coeruleus (LC) is involved since it is essential for the maintenance of muscle tone, and ceases to fire during cataplectic attacks. Furthermore, alpha-2 adrenoceptors proliferate in the LC in cataplexy, probably due to 'heterologous denervation supersensitivity' resulting from the loss/weakening of the orexinergic input to the LC. This would lead to the sensitization of the autoinhibition mechanism of LC neurones mediated by inhibitory alpha-2 adrenoceptors ('autoreceptors'). Thus the excitatory input from the amygdala to the LC, activated by an emotional stimulus, would lead to the 'switching off' of LC activity via the supersensitive auto-inhibition mechanism. GHB is an agonist at both γ-aminobutyric acid (GABA) GABA (B) and GHB receptors that may be a subtype of an extrasynaptic GABA(A) receptor. GHB may prevent a cataplectic attack by dampening the tone of LC neurones via the stimulation of inhibitory extrasynaptic GABA receptors in the LC, and thus increasing the threshold for autoinhibition. PMID:25735989

  4. γ-Hydroxybutyrate (GHB)-induced respiratory depression: combined receptor-transporter inhibition therapy for treatment in GHB overdose.

    PubMed

    Morse, Bridget L; Vijay, Nisha; Morris, Marilyn E

    2012-08-01

    Overdose of γ-hydroxybutyrate (GHB) frequently causes respiratory depression, occasionally resulting in death; however, little is known about the dose-response relationship or effects of potential overdose treatment strategies on GHB-induced respiratory depression. In these studies, the parameters of respiratory rate, tidal volume, and minute volume were measured using whole-body plethysmography in rats administered GHB. Intravenous doses of 200, 600, and 1500 mg/kg were administered to assess the dose-dependent effects of GHB on respiration. To determine the receptors involved in GHB-induced respiratory depression, a specific GABA(B) receptor antagonist, (2S)-(+)-5,5-dimethyl-2-morpholineacetic acid (SCH50911), and a specific GABA(A) receptor antagonist, bicuculline, were administered before GHB. The potential therapeutic strategies of receptor inhibition and monocarboxylate transporter (MCT) inhibition were assessed by inhibitor administration 5 min after GHB. The primary effect of GHB on respiration was a dose-dependent decrease in respiratory rate, accompanied by an increase in tidal volume, resulting in little change in minute volume. Pretreatment with 150 mg/kg SCH50911 completely prevented the decrease in respiratory rate, indicating agonism at GABA(B) receptors to be primarily responsible for GHB-induced respiratory depression. Administration of 50 mg/kg SCH50911 after GHB completely reversed the decrease in respiratory rate; lower doses had partial effects. Administration of the MCT inhibitor l-lactate increased GHB renal and total clearance, also improving respiratory rate. Administration of 5 mg/kg SCH50911 plus l-lactate further improved respiratory rate compared with the same dose of either agent alone, indicating that GABA(B) and MCT inhibitors, alone and in combination, represent potential treatment options for GHB-induced respiratory depression. PMID:22561075

  5. γ-Hydroxybutyrate (GHB)-Induced Respiratory Depression: Combined Receptor-Transporter Inhibition Therapy for Treatment in GHB Overdose

    PubMed Central

    Morse, Bridget L.; Vijay, Nisha

    2012-01-01

    Overdose of γ-hydroxybutyrate (GHB) frequently causes respiratory depression, occasionally resulting in death; however, little is known about the dose-response relationship or effects of potential overdose treatment strategies on GHB-induced respiratory depression. In these studies, the parameters of respiratory rate, tidal volume, and minute volume were measured using whole-body plethysmography in rats administered GHB. Intravenous doses of 200, 600, and 1500 mg/kg were administered to assess the dose-dependent effects of GHB on respiration. To determine the receptors involved in GHB-induced respiratory depression, a specific GABAB receptor antagonist, (2S)-(+)-5,5-dimethyl-2-morpholineacetic acid (SCH50911), and a specific GABAA receptor antagonist, bicuculline, were administered before GHB. The potential therapeutic strategies of receptor inhibition and monocarboxylate transporter (MCT) inhibition were assessed by inhibitor administration 5 min after GHB. The primary effect of GHB on respiration was a dose-dependent decrease in respiratory rate, accompanied by an increase in tidal volume, resulting in little change in minute volume. Pretreatment with 150 mg/kg SCH50911 completely prevented the decrease in respiratory rate, indicating agonism at GABAB receptors to be primarily responsible for GHB-induced respiratory depression. Administration of 50 mg/kg SCH50911 after GHB completely reversed the decrease in respiratory rate; lower doses had partial effects. Administration of the MCT inhibitor l-lactate increased GHB renal and total clearance, also improving respiratory rate. Administration of 5 mg/kg SCH50911 plus l-lactate further improved respiratory rate compared with the same dose of either agent alone, indicating that GABAB and MCT inhibitors, alone and in combination, represent potential treatment options for GHB-induced respiratory depression. PMID:22561075

  6. Comparative genomics of aldehyde dehydrogenase 5a1 (succinate semialdehyde dehydrogenase) and accumulation of gamma-hydroxybutyrate associated with its deficiency

    PubMed Central

    2009-01-01

    Succinic semialdehyde dehydrogenase (SSADH; aldehyde dehydrogenase 5A1 [ALDH5A1]; locus 6p22) occupies a central position in central nervous system (CNS) neurotransmitter metabolism as one of two enzymes necessary for γ-aminobutyric acid (GABA) recycling from the synaptic cleft. Its importance is highlighted by the neurometabolic disease associated with its inherited deficiency in humans, as well as the severe epileptic phenotype observed in Aldh5a1-/- knockout mice. Expanding evidence now suggests, however, that even subtle decreases in human SSADH activity, associated with rare and common single nucleotide polymorphisms, may produce subclinical pathological effects. SSADH, in conjunction with aldo-keto reductase 7A2 (AKR7A2), represent two neural enzymes responsible for further catabolism of succinic semialdehyde, producing either succinate (SSADH) or γ-hydroxybutyrate (GHB; AKR7A2). A GABA analogue, GHB is a short-chain fatty alcohol with unusual properties in the CNS and a long pharmacological history. Moreover, SSADH occupies a further role in the CNS as the enzyme responsible for further metabolism of the lipid peroxidation aldehyde 4-hydroxy-2-nonenal (4-HNE), an intermediate known to induce oxidant stress. Accordingly, subtle decreases in SSADH activity may have the capacity to lead to regional accumulation of neurotoxic intermediates (GHB, 4-HNE). Polymorphisms in SSADH gene structure may also associate with quantitative traits, including intelligence quotient and life expectancy. Further population-based studies of human SSADH activity promise to reveal additional properties of its function and additional roles in CNS tissue. PMID:19164088

  7. Development of a fluorescent sensor for illicit date rape drug GHB.

    PubMed

    Zhai, Duanting; Tan, Yong Qiao Elton; Xu, Wang; Chang, Young-Tae

    2014-03-18

    The first fluorescent sensor (GHB Orange) for date rape drug GHB was developed. It exhibits the fluorescence quenching property for GHB and allows its detection in various drinks. The interaction mechanism was elucidated as intramolecular charge transfer induced by a hydrogen bond. This discovery will help in solving the drug facilitated sexual assault problems. PMID:24492471

  8. Reconsidering GHB: orphan drug or new model antidepressant?

    PubMed

    Bosch, Oliver G; Quednow, Boris B; Seifritz, Erich; Wetter, Thomas C

    2012-05-01

    For six decades, the principal mode of action of antidepressant drugs is the inhibition of monoamine re-uptake from the synaptic cleft. Tricyclic antidepressants, selective serotonin re-uptake inhibitors (SSRIs) and the new generation of dual antidepressants all exert their antidepressant effects by this mechanism. In the early days of the monoaminergic era, other efforts have been made to ameliorate the symptoms of depression by pharmacological means. The gamma-aminobutyric acid (GABA) system was and possibly still is one of the main alternative drug targets. Gammahydroxybutyrate (GHB) was developed as an orally active GABA analogue. It was tested in animal models of depression and human studies. The effects on sleep, agitation, anhedonia and depression were promising. However, the rise of benzodiazepines and tricyclic antidepressants brought GHB out of the scope of possible treatment alternatives. GHB is a GABA(B) and GHB receptor agonist with a unique spectrum of behavioural, neuroendocrine and sleep effects, and improves daytime sleepiness in various disorders such as narcolepsy, Parkinson's disease and fibromyalgia. Although it was banned from the US market at the end of the 1990s because of its abuse and overdose potential, it later was approved for the treatment of narcolepsy. New research methods and an extended view on other neurotransmitter systems as possible treatment targets of antidepressant treatment brought GHB back to the scene. This article discusses the unique neurobiological effects of GHB, its misuse potential and possible role as a model substance for the development of novel pharmacological treatment strategies in depressive disorders. PMID:21926421

  9. GHB receptor targets in the CNS: focus on high-affinity binding sites.

    PubMed

    Bay, Tina; Eghorn, Laura F; Klein, Anders B; Wellendorph, Petrine

    2014-01-15

    γ-Hydroxybutyric acid (GHB) is an endogenous compound in the mammalian brain with both low- and high-affinity receptor targets. GHB is used clinically in the treatment of symptoms of narcolepsy and alcoholism, but also illicitly abused as the recreational drug Fantasy. Major pharmacological effects of exogenous GHB are mediated by GABA subtype B (GABAB) receptors that bind GHB with low affinity. The existence of GHB high-affinity binding sites has been known for more than three decades, but the uncovering of their molecular identity has only recently begun. This has been prompted by the generation of molecular tools to selectively study high-affinity sites. These include both genetically modified GABAB knock-out mice and engineered selective GHB ligands. Recently, certain GABA subtype A (GABAA) receptor subtypes emerged as high-affinity GHB binding sites and potential physiological mediators of GHB effects. In this research update, a description of the various reported receptors for GHB is provided, including GABAB receptors, certain GABAA receptor subtypes and other reported GHB receptors. The main focus will thus be on the high-affinity binding targets for GHB and their potential functional roles in the mammalian brain. PMID:24269284

  10. ?-Hydroxybutyric Acid (GHB) Is Not an Agonist of Extrasynaptic GABAA Receptors

    PubMed Central

    Connelly, William M.; Errington, Adam C.; Crunelli, Vincenzo

    2013-01-01

    ?-Hydroxybutyric acid (GHB) is an endogenous compound and a drug used clinically to treat the symptoms of narcolepsy. GHB is known to be an agonist of GABAB receptors with millimolar affinity, but also binds with much higher affinity to another site, known as the GHB receptor. While a body of evidence has shown that GHB does not bind to GABAA receptors widely, recent evidence has suggested that the GHB receptor is in fact on extrasynaptic ?4?1? GABAA receptors, where GHB acts as an agonist with an EC50 of 140 nM. We investigated three neuronal cell types that express a tonic GABAA receptor current mediated by extrasynaptic receptors: ventrobasal (VB) thalamic neurons, dentate gyrus granule cells and striatal medium spiny neurons. Using whole-cell voltage clamp in brain slices, we found no evidence that GHB (10 M) induced any GABAA receptor mediated current in these cell types, nor that it modulated inhibitory synaptic currents. Furthermore, a high concentration of GHB (3 mM) was able to produce a GABAB receptor mediated current, but did not induce any other currents. These results suggest either that GHB is not a high affinity agonist at native ?4?1? receptors, or that these receptors do not exist in classical areas associated with extrasynaptic currents. PMID:24244421

  11. A surrogate analyte-based LC-MS/MS method for the determination of ?-hydroxybutyrate (GHB) in human urine and variation of endogenous urinary concentrations of GHB.

    PubMed

    Kang, Soyoung; Oh, Seung Min; Chung, Kyu Hyuck; Lee, Sooyeun

    2014-09-01

    ?-Hydroxybutyrate (GHB) is a drug of abuse with a strong anesthetic effect; however, proving its ingestion through the quantification of GHB in biological specimens is not straightforward due to the endogenous presence of GHB in human blood, urine, saliva, etc. In the present study, a surrogate analyte approach was applied to accurate quantitative determination of GHB in human urine using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in order to overcome this issue. For this, (2)H6-GHB and (13)C2-dl-3-hydroxybutyrate were used as a surrogate standard and as an internal standard, respectively, and parallelism between the surrogate analyte approach and standard addition was investigated at the initial step. The validation results proved the method to be selective, accurate, and precise, with acceptable linearity within calibration ranges (0.1-1?g/ml). The limit of detection and the limit of quantification of (2)H6-GHB were 0.05 and 0.1?g/ml, respectively. No significant variations were observed among urine matrices from different sources. The stability of (2)H6-GHB was satisfactory under sample storage and in-process conditions. However, in vitro production of endogenous GHB was observed when the urine sample was kept under the in-process condition for 4h and under the storage conditions of 4 and -20C. In order to facilitate the practical interpretation of urinary GHB, endogenous GHB was accurately measured in urine samples from 79 healthy volunteers using the surrogate analyte-based LC-MS/MS method developed in the present study. The unadjusted and creatinine-adjusted GHB concentrations in 74 urine samples with quantitative results ranged from 0.09 to 1.8?g/ml and from 4.5 to 530?g/mmol creatinine, respectively. No significant correlation was observed between the unadjusted and creatinine-adjusted GHB concentrations. The urinary endogenous GHB concentrations were affected by gender and age while they were not significantly influenced by habitual smoking, alcohol drinking, or caffeine-containing beverage drinking. PMID:24929871

  12. Drug facilitated sexual assault with lethal outcome: GHB intoxication in a six-year-old girl.

    PubMed

    Mehling, Lena-Maria; Johansen, Sys Stybe; Wang, Xin; Doberentz, Elke; Madea, Burkhard; Hess, Cornelius

    2016-02-01

    A very serious case of DFSA (drug facilitated sexual assault) is presented, in which a six-year-old girl died following sedation with γ-hydroxybutyric acid (GHB). She had been sexually abused by a relative. Samples of cardiac blood, bile, vitreous humour, liver, kidney, brain tissues and hair were analysed by a LC-MS/MS method. The following GHB concentrations were determined: cardiac blood: 150 mg/l; bile: 292mg/l; vitreous humour: 58mg/l; liver: 100 mg/kg; kidney: 124.5 mg/kg, brain: 110 mg/kg. Very high GHB levels were found in the proximal part of the hair sample (about 40.9 ng/mg). In distal segments of hair - up to 12 cm distant from the hair scalp - GHB concentrations were higher than the overall found endogenous range of 2-3 ng/mg. Police investigations revealed that the uncle had also administered GHB to the older half-sister. Therefore, a sample of her hair was analysed accordingly, but unremarkable results were obtained. Comparing our toxicological results with police investigations and the offender's statements it can be assumed that the 6-year-old girl had ingested GHB. By exclusion of other causes of death a lethal intoxication with GHB could be confirmed. PMID:26774600

  13. Uptake of gamma-valerolactone--detection of gamma-hydroxyvaleric acid in human urine samples.

    PubMed

    Andresen-Streichert, H; Jungen, H; Gehl, A; Müller, A; Iwersen-Bergmann, S

    2013-05-01

    Gamma-valerolactone (GVL) is reported to be a substance that can be used as a legal substitute for gamma-hydroxybutyric acid (GHB), which is currently a controlled substance in several countries. Unlike gamma-butyrolactone and 1,4-butanediol, GVL is not metabolized to GHB, which causes the effects after uptake of these two chemicals. In the case of GVL, the lactone ring is split to gamma-hydroxyvaleric acid (GHV or 4-methyl-GHB) by a lactonase. Because of its affinity for the GHB receptor, GHV reveals similar effects to GHB, although it is less potent. Intoxications with GVL, or its use as a date rape drug, are conceivable. Despite these facts, there are no publications in the literature regarding detections of GHV in human samples. This study reports three cases, including five urine samples, in which GHV could be detected in concentrations between 3 and 5.8 mg/L. In one of these cases, a drug-facilitated sexual assault (DFSA) was assumed; four of these samples were from two people suspected of abusing GHB. The results indicate that GVL is used as an alternative to GHB and its precursors and should be taken seriously. GVL or GHV should be included in toxicological analysis, particularly in DFSA cases. More information is needed regarding the pharmacokinetics of GVL/GHV for the meaningful interpretation of positive or negative results. PMID:23486087

  14. Anion exchange SPE and liquid chromatography-tandem mass spectrometry in GHB analysis.

    PubMed

    Elian, Albert A; Hackett, Jeffery

    2011-12-01

    In this study, the extraction of γ-hydroxybutyrate (GHB) from urine using solid-phase extraction (SPE) is described. SPE was performed on anion exchange columns after samples of urine had been diluted with de-ionized water. After application of the diluted samples containing GHB-d(6) as an internal standard, the sorbent was washed with deionized water and methanol and dried. The GHB was eluted from the SPE column with a solvent consisting of methanol containing 6% glacial acetic acid. The eluent was collected, evaporated to dryness, and dissolved in mobile phase (100 μL) for analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in negative multiple reaction monitoring (MRM) mode. Liquid chromatography was performed in gradient mode employing a biphenyl column and a mobile phase consisting of acetontitrile (containing 0.1% formic acid) and 0.1% aqueous formic acid. The total run time for each analysis was less than 5 min. The limits of detection/quantification for this method were determined to be 50 and 100 ng/mL, respectively. The method was found to be linear from 500 ng/mL to 10,000 ng/mL (r(2)>0.995). The recovery of GHB was found to be greater than 75%. In this report, results of authentic urine samples analyzed for GHB by this method are presented. GHB concentrations in these samples were found to be range from less than 500 ng/mL to 5110 ng/mL. PMID:22055831

  15. Determination of endogenous levels of GHB in human hair. Are there possibilities for the identification of GHB administration through hair analysis in cases of drug-facilitated sexual assault?

    PubMed

    Goullé, Jean Pierre; Chèze, Marjorie; Pépin, Gilbert

    2003-01-01

    We have developed a GC-MS-MS assay for GHB in human hair. Five milligrams of washed hair were hydrolyzed by 1M or 0.01M NaOH before a liquid-liquid extraction with ethyl acetate under acidic conditions. GHB-d(6) was used as the internal standard. TMS derivatives were formed before injection. TBDMS derivatives were used in cases of strong chromatographic interferences or in a confirmatory procedure. Analysis of basal levels of GHB in 61 drug-free donors gave the following results: the mean measured concentration for blond hair was 0.60 ng/mg (n = 12), SD = 0.19 ng/mg, and extreme figures were in the range 0.35-0.95 ng/mg. For brown hair, the mean measured concentration was 0.90 ng/mg (n = 30), SD = 0.42 ng/mg, and extreme figures 0.41-1.86 ng/mg. For black hair, the mean measured concentration was 0.90 ng/mg (n = 19), SD = 0.37 ng/mg, and extreme figures 0.32-1.54 ng/mg, showing no significant differences depending on hair color. Analysis of basal levels of GHB of 12 or more specimens in segmented hair showed a mean concentration of 1.22 ng/mg (0.31-8.4 ng/mg) and a relative standard deviation for each individual ranging from 6.75% to 37.98%. GHB was administered to a healthy 53-year-old white male (light brown hair) at oral dosages of 30, 45, and 60 mg/kg. Beard hair was collected just before administration and 24 h after (and each day for one week for the last dose), and a 7.5-cm scalp hair lock was collected 7 days after the last dose. A rise in GHB concentration was observed in beard hair for the 45 and 60 mg/kg dosages with a maximum at 24 h, whereas no change was observed for the 30 mg/kg dosage. Scalp hair was segmented into 3-mm long segments. The three proximal last segments showed significantly (0.0005 < p < 0.005) different concentrations of GHB (1.22, 1.27, and 1.66 ng/mg, respectively) when compared with the basal physiological level of GHB in this same person (mean = 0.62 ng/mg, SD = 0.15 ng/mg). A case of daily GHB abuse during bodybuilding allowed us to determine a concentration of GHB of 14 ng/mg, in a 2-cm long segment (black hair). A case of rape under the influence of GHB was documented through hair analysis (black hair) and positive analysis of the glass she used. Sampled 7 days after the sexual assault, the three last 3-mm long proximal segments tested for GHB exhibited concentrations of 3.1-5.3 and 4.3 ng/mg, respectively, whereas the mean physiological level determined in this woman was 0.71 ng/mg, SD = 0.17 ng/mg. The authors advise a two-step hair sampling as evidence of GHB consumption: the first sample at the time of exposure to show the contamination by sweat of the proximal segment in case of recent administration with a significant rise of hair level at the root, and the second after at least 3 or 4 weeks to avoid this contamination and determine the levels incorporated in the hair matrix before, during, and after the exposure. PMID:14670136

  16. New Synthesis and Tritium Labeling of a Selective Ligand for Studying High-affinity ?-Hydroxybutyrate (GHB) Binding Sites

    PubMed Central

    Vogensen, Stine B.; Marek, Ale; Bay, Tina; Wellendorph, Petrine; Kehler, Jan; Bundgaard, Christoffer; Frlund, Bente; Pedersen, Martin H.F.; Clausen, Rasmus P.

    2013-01-01

    3-Hydroxycyclopent-1-enecarboxylic acid (HOCPCA, 1) is a potent ligand for the high-affinity GHB binding sites in the CNS. An improved synthesis of 1 together with a very efficient synthesis of [3H]-1 is described. The radiosynthesis employs in situ generated lithium trimethoxyborotritide. Screening of 1 against different CNS targets establishes a high selectivity and we demonstrate in vivo brain penetration. In vitro characterization of [3H]-1 binding shows high specificity to the high-affinity GHB binding sites. PMID:24053696

  17. Drug-Facilitated Sexual Assault on Campus: Challenges and Interventions.

    ERIC Educational Resources Information Center

    Hensley, Laura G.

    2002-01-01

    The use of gamma-hydroxybutyric acid (GHB) to facilitate sexual assault is increasing on campuses nationwide. This article provides college counselors with an overview of the use of GHB in campus sexual assault, outlines suggestions for crisis intervention, and discusses the challenges of counseling survivors of drug-facilitated sexual assault.…

  18. Pharmacokinetics of GHB and detection window in serum and urine after single uptake of a low dose of GBL - an experiment with two volunteers.

    PubMed

    Schröck, Alexandra; Hari, Yvonne; König, Stefan; Auwärter, Volker; Schürch, Stefan; Weinmann, Wolfgang

    2014-04-01

    During the last few years γ-hydroxybutyric acid (GHB) and γ-butyrolactone (GBL) have attracted much interest as recreational drugs and knock-out drops in drug-facilitated sexual assaults. This experiment aims at getting an insight into the pharmacokinetics of GHB after intake of GBL. Therefore Two volunteers took a single dose of 1.5 ml GBL, which had been spiked to a soft drink. Assuming that GBL was completely metabolized to GHB, the corresponding amount of GHB was 2.1 g. Blood and urine samples were collected 5 h and 24 h after ingestion, respectively. Additionally, hair samples (head hair and beard hair) were taken within four to five weeks after intake of GBL. Samples were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) after protein precipitation with acetonitrile. The following observations were made: spiked to a soft drink, GBL, which tastes very bitter, formed a liquid layer at the bottom of the glass, only disappearing when stirring. Both volunteers reported weak central effects after approximately 15 min, which disappeared completely half an hour later. Maximum concentrations of GHB in serum were measured after 20 min (95 µg/ml and 106 µg/ml). Already after 4-5 h the GHB concentrations in serum decreased below 1 µg/ml. In urine maximum GHB concentrations (140 µg/ml and 120 µg/ml) were measured after 1-2 h, and decreased to less than 1 µg/ml within 8-10 h. The ratio of GHB in serum versus blood was 1.2 and 1.6. PMID:23733593

  19. A novel quadruplex real-time PCR method for simultaneous detection of Cry2Ae and two genetically modified cotton events (GHB119 and T304-40)

    PubMed Central

    2014-01-01

    Background To date, over 150 genetically modified (GM) crops are widely cultivated. To comply with regulations developed for genetically modified organisms (GMOs), including labeling policies, many detection methods for GMO identification and quantification have been developed. Results To detect the entrance and exit of unauthorized GM crop events in China, we developed a novel quadruplex real-time PCR method for simultaneous detection and quantification of GM cotton events GHB119 and T304-40 in cotton-derived products (based on the 5′-flanking sequence) and the insect-resistance gene Cry2Ae. The limit of detection was 10 copies for GHB119 and Cry2Ae and 25 copies for T304-40. The limit of quantification was 25 copies for GHB119 and Cry2Ae and 50 copies for T304-40. Moreover, low bias and acceptable standard deviation and relative standard deviation values were obtained in quantification analysis of six blind samples containing different GHB119 and T304-40 ingredients. Conclusions The developed quadruplex quantitative method could be used for quantitative detection of two GM cotton events (GHB119 and T304-40) and Cry2Ae gene ingredient in cotton derived products. PMID:24884946

  20. Simultaneous analysis method for GHB, ketamine, norketamine, phenobarbital, thiopental, zolpidem, zopiclone and phenytoin in urine, using C18 poroshell column.

    PubMed

    Anilanmert, Beril; Çavuş, Fatma; Narin, Ibrahim; Cengiz, Salih; Sertler, Şefika; Özdemir, Ali Acar; Açikkol, Münevver

    2016-06-01

    Date-rape drugs have the potential to be used in drug-facilitated sexual assault, organ theft and property theft. Since they are colorless, tasteless and odorless, victims can drink without noticing, when added to the beverages. These drugs must be detected in time, before they are cleared up from the biofluids. A simultaneous extraction and determination method in urine for GHB, ketamine, norketamine, phenobarbital, thiopental, zolpidem, zopiclone and phenytoin (an anticonvulsant and antiepileptic drug) with LC-MS/MS was developed for the first time with analytically acceptable recoveries and validated. A 4 steps liquid-liquid extraction was applied, using only 1.000mL urine. A new age commercial C18 poroshell column with high column efficiency was used for LC-MS/MS analysis with a fast isocratic elution as 5.5min. A new MS transition were introduced for barbital. 222.7>179.8 with the effect of acetonitrile. Recoveries (%) were between 80.98-99.27 for all analytes, except for GHB which was 71.46. LOD and LOQ values were found in the ranges of 0.59-49.50 and 9.20-80.80ngmL(-1) for all the analytes (except for GHB:3.44 and 6.00μgmL(-1)). HorRat values calculated (between 0.25-1.21), revealed that the inter-day and interanalist precisions (RSD%≤14.54%) acceptable. The simultaneous extraction and determination of these 8 analytes in urine is challenging because of the difficulty arising from the different chemical properties of some. Since the procedure can extract drugs from a wide range of polarity and pKa, it increases the window of detection. Group representatives from barbiturates, z-drugs, ketamine, phenytoin and polar acidic drugs (GHB) have been successfully analyzed in this study with low detection limits. The method is important from the point of determining the combined or single use of these drugs in crimes and finding out the reasons of deaths related to these drugs. PMID:27107852

  1. Club Drugs

    MedlinePlus

    ... include Methylenedioxymethamphetamine (MDMA), also known as Ecstasy XTC, X, E, Adam, Molly, Hug Beans, and Love Drug Gamma-hydroxybutyrate (GHB), also known as G, Liquid Ecstasy, and Soap Ketamine, also known as Special K, K, Vitamin K, and Jet Rohypnol, also known as Roofies ...

  2. In Vitro and In Vivo Evidence for Active Brain Uptake of the GHB Analog HOCPCA by the Monocarboxylate Transporter Subtype 1.

    PubMed

    Thiesen, Louise; Kehler, Jan; Clausen, Rasmus P; Frølund, Bente; Bundgaard, Christoffer; Wellendorph, Petrine

    2015-08-01

    γ-Hydroxybutyric acid (GHB) is a recreational drug, a clinically prescribed drug in narcolepsy and alcohol dependence, and an endogenous substance that binds to both high- and low-affinity sites in the brain. For studying the molecular mechanisms and the biologic role of the GHB high-affinity binding sites, ligands with high and specific affinity are essential. The conformationally restricted GHB analog HOCPCA (3-hydroxycyclopent-1-enecarboxylic acid) is one such compound. The objective of this study was to investigate the transport of HOCPCA across the blood-brain barrier in vitro and in vivo and to investigate the hypothesis that HOCPCA, like GHB, is a substrate for the monocarboxylate transporters (MCTs). For in vitro uptake studies, MCT1, -2, and -4 were recombinantly expressed in Xenopus laevis oocytes, and the previously reported radioligand [(3)H]HOCPCA was used as substrate. HOCPCA inhibited the uptake of the endogenous MCT substrate l-[(14)C]lactate, and [(3)H]HOCPCA was shown to act as substrate for MCT1 and 2 (Km values in the low- to mid-millimolar range). Introducing single-point amino acid mutations into positions essential for MCT function supported that HOCPCA binds to the endogenous substrate pocket of MCTs. MCT1-mediated brain entry of HOCPCA (10 mg/kg s.c.) was further confirmed in vivo in mice by coadministration of increasing doses of the MCT inhibitor AR-C141990 [(R)-5-(3-hydroxypyrrolidine-1-carbonyl)-1-isobutyl-3-methyl-6-(quinolin-4-ylmethyl)thieno[2,3-d]pyrimidine-2,4(1H,3H)-dione], which inhibited brain penetration of HOCPCA in a dose-dependent manner (ID50 = 4.6 mg/kg). Overall, our study provides evidence that MCT1 is an important brain entry site for HOCPCA and qualifies for future in vivo studies with HOCPCA. PMID:25986445

  3. Determination of endogenous concentration of γ-hydroxybutyric acid (GHB) in hair through an ad hoc GC-MS analysis: A study on a wide population and influence of gender and age.

    PubMed

    Vaiano, Fabio; Serpelloni, Giovanni; Furlanetto, Sandra; Palumbo, Diego; Mari, Francesco; Fioravanti, Alessia; Bertol, Elisabetta

    2016-01-25

    γ-Hydroxybutyric acid (GHB) spread for recreational purposes or as "rape drug" represents a hard issue for forensic toxicologists due to its endogenous nature. It is clear that an actual and reliable discrimination between basal and exogenous levels is mandatory to achieve a correct evaluation of conscious/unconscious administration. This research aimed to study the GHB baseline in hair samples, collected from 150 volunteers, non-consumers of any drugs of abuse, in order to evaluate if a generic cut-off value could be accepted, also focusing on potential influences of gender and age. The analysis consisted of an overnight incubation with NaOH at 56 °C, liquid-liquid extraction with ethylacetate and trimethylsylil derivatization. Detection was carried out through gas chromatography-mass spectrometry in single ion monitoring (m/z 233, 234, 147 for GHB; m/z 239, 240 and 147 for GHB-d6). The endogenous amount in "blank" hair was estimated by the standard addition method. Concentration range was 0.279-2.839 ng/mg. In males, the average GHB levels were higher than in females (0.829 vs 0.596 ng/mg, respectively), especially in the first age category (<30 years, 1.008 vs 0.606 ng/mg, respectively). Age influences on GHB levels seemed to be different among the two sexes: in male population concentrations were higher <30 (1.008 ng/mg) and similar in the other age ranges (0.762 ng/mg, 30-50; 0.763 ng/mg, >50); in female, quite similar levels were registered throughout all the age categories (0.606 ng/mg, <30; 0.536 ng/mg, 30-50; 0.691 ng/mg, >50). Further study should be performed on GHB physiology in order to better understand these differences among ages and genders. Moreover, we demonstrated that for hair analysis a cut-off reference value is not strictly mandatory, underlining the great interpretative valence of segmental analysis. PMID:26551534

  4. Polyimide Precursor Solid Residuum

    NASA Technical Reports Server (NTRS)

    Weiser, Erik S. (Inventor); St.Clair, Terry L. (Inventor); Echigo, Yoshiaki (Inventor); Kaneshiro, Hisayasu (Inventor)

    2001-01-01

    A polyimide precursor solid residuum is an admixture of an aromatic dianhydride or derivative thereof and an aromatic diamine or derivative thereof plus a complexing agent, which is complexed with the admixture by hydrogen bonding. The polyimide precursor solid residuum is effectively employed in the preparation of polyimide foam and the fabrication of polyimide foam structures.

  5. ?-Hydroxybutyrate (Xyrem) ameliorates clinical symptoms and neuropathology in a mouse model of Alzheimer's disease.

    PubMed

    Klein, Christian; Mathis, Chantal; Leva, Graldine; Patte-Mensah, Christine; Cassel, Jean-Christophe; Maitre, Michel; Mensah-Nyagan, Ayikoe G

    2015-02-01

    The chronic decrease of brain amyloid-? (A?) peptides is an emerging therapeutic for Alzheimer's disease, but no such treatment has achieved clinical validation yet. In vivo, some brain proteases, including neprilysin, possess the ability of degrading A? and experimental data suggest their exploitation in strategies to reduce cerebral A? concentration. Previous studies have shown that pharmacologic doses of gamma-hydroxybutyrate (sodium oxybate or Xyrem) induce histone deacetylases (HDACs) inhibition and neprilysin gene expression. Here, we demonstrate that brain neprilysin overexpression induced in vivo by repeated gamma-hydroxybutyrate autoadministration reduces cerebral A? contents and prevents cognitive deficits in APPSWE mice. Oral gamma-hydroxybutyrate also counteracted phosphoramidon-induced brain neprilysin inhibition and A? accumulation. HDACs activities in SH-SY5Y cells were inhibited by gamma-hydroxybutyrate which did not affect amyloid peptide precursor intracellular domain. Together, our results suggest that gamma-hydroxybutyrate, acting via HDAC inhibition, upregulates neprilysin to reduce A? level and related memory deficits. Because gamma-hydroxybutyrate doses used herein are clinically relevant, our data suggest that chronic oral administration of gamma-hydroxybutyrate or its analogs may be considered for strategies against presymptomatic or established Alzheimer's disease. PMID:25457559

  6. Isomeric Trisaryloxycyclotriphosphazene Polymer Precursors

    NASA Technical Reports Server (NTRS)

    St. Clair, Terry L.; Kumar, Devendra

    1990-01-01

    Substances useful for making heat-and fire-resistant polymers. Cyclotriphosphazene-based monomers and polymer precursors led to development of high-temperature materials. Cyclotriphosphazene-derived monomers, polymer precursors, and polymers becoming important from both industrial and scientific points of view. Presence of phosphazene moiety in cyclotriphosphazene-based monomers and polymer precursors expected to impact special properties in desired high-performance materials containing inorganic backbones for aerospace applications. Useful for obtaining heat-and fire-resistant polymers for composites, adhesives, molding powders, and coating laminates. Also used in structures (e.g. secondary structures in aircraft), in construction of spacecraft, and in electronics and computer industries.

  7. Earthquakes: hydrogeochemical precursors

    USGS Publications Warehouse

    Ingebritsen, Steven E.; Manga, Michael

    2014-01-01

    Earthquake prediction is a long-sought goal. Changes in groundwater chemistry before earthquakes in Iceland highlight a potential hydrogeochemical precursor, but such signals must be evaluated in the context of long-term, multiparametric data sets.

  8. [Fatigue in substance abuse disorders].

    PubMed

    Aichmller, Claus; Soyka, Michael

    2015-04-22

    Fatigue is a common symptom in substance abuse disorders. The most frequent and relevant addiction disorders like alcoholism and dependence of illegal drugs like THC, opioids, cocaine, ecstasy, psycho-stimulants, and GHB/GBL (gamma hydroxybutyrate/gamma butyrolactone; "Liquid Ecstasy") are described, especially the associated symptomatology and specific psychosocial features. The dependence on drugs like benzodiazepines, analgesics, amphetamines and others is also outlined. The distinction between justified and abusive consumption can often be difficult. PMID:26072600

  9. Precursors to Pancreatic Cancer+

    PubMed Central

    Hruban, Ralph H.; Maitra, Anirban; Kern, Scott E.; Goggins, Michael

    2008-01-01

    Infiltrating ductal adenocarcinoma of the pancreas is believed to arise from morphologically distinct non-invasive precursor lesions. These precursors include the intraductal papillary mucinous neoplasm, the mucinous cystic neoplasm, and pancreatic intraepithelial neoplasia. Intraductal papillary mucinous neoplasms are grossly visible mucin-producing epithelial neoplasms that arise in the main pancreatic duct or one of its branches. The cysts of mucinous cystic neoplasms do not communicate with the major pancreatic ducts and these neoplasms are characterized by a distinct ovarian-type stroma. Pancreatic intraepithelial neoplasia is a microscopic lesion. This review focuses on the clinical significance of these three remarkable precursor lesions with emphasis on their clinical manifestations, detection, and treatment. PMID:17996793

  10. Multiple myeloma precursor disease.

    PubMed

    Landgren, Ola; Waxman, Adam Justin

    2010-12-01

    Recent data indicate that multiple myeloma is consistently preceded by the precursor states of monoclonal gammopathy of undetermined significance (MGUS) and smoldering myeloma. Currently, multiple myeloma is a clinical diagnosis based on manifestations including hypercalcemia, renal failure, anemia, and bone lesions, whereas MGUS and smoldering myeloma are diagnosed based on laboratory abnormalities. Current clinical markers allow for more individualized risk stratification and counseling of these patients. However, there is a dearth of biomarkers and molecular imaging techniques capable of (1) accurately identifying patients with disease biology corresponding with high risk of progression; (2) elucidating the mechanism of transformation to multiple myeloma; and (3) forming a framework for development of targeted therapies. This case presentation and review discusses the current understanding of myeloma precursor disease and future opportunities for improving personalized management of patients with MGUS or smoldering myeloma, as well as the potential for developing early treatment strategies designed to delay and prevent development of multiple myeloma. PMID:21119086

  11. 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 directional techniques were employed, resulting in three mapped, potential epicenters. The remaining, weaker signals presented similar directionality results to more epicentral locations. In addition, the directional results of the Timpson field tests lead to the design and construction of a third prototype antenna. In a laboratory setting, experiments were created to fail igneous rock types within a custom-designed Faraday Cage. An antenna emplaced within the cage detected EM emissions, which were both reproducible and distinct, and the laboratory results paralleled field results. With a viable system and continuous monitoring, a fracture cycle could be established and observed in real-time. Sequentially, field data would be reviewed quickly for assessment; thus, leading to a much improved earthquake forecasting capability. The EM precursor determined by this method may surpass all prior precursor claims, and the general public will finally receive long overdue forecasting.

  12. Biosynthetic precursors of deazaflavins.

    PubMed Central

    Reuke, B; Korn, S; Eisenreich, W; Bacher, A

    1992-01-01

    The incorporation of 13C- and 14C-labeled precursors into 5-deaza-7,8-didemethyl-8-hydroxyriboflavin (factor F0) was studied with growing cells of Methanobacterium thermoautotrophicum. 5-Amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione was incorporated into the deazaflavin and into riboflavin without dilution. Tyrosine and 4-hydroxyphenylpyruvate were incorporated into the deazaflavin and into cellular protein. 4-Hydroxybenzaldehyde was not incorporated. A reaction mechanism is proposed for the formation of the deazaflavin chromophore from 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione and tyrosine or 4-hydroxyphenylpyruvate. PMID:1350778

  13. 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 recurrence, duration, and frequency response. At the Southern California field sites, one loop antenna was positioned for omni-directional reception and also detected a strong First Schumann Resonance; however, additional Schumann Resonances were absent. At the Timpson, TX field sites, loop antennae were positioned for directional reception, due to earthquake-induced, hydraulic fracturing activity currently conducted by the oil and gas industry. Two strong signals, one moderately strong signal, and approximately 6-8 weaker signals were detected in the immediate vicinity. The three stronger signals were mapped by a biangulation technique, followed by a triangulation technique for confirmation. This was the first antenna mapping technique ever performed for determining possible earthquake epicenters. Six and a half months later, Timpson experienced two M4 (M4.1 and M4.3) earthquakes on September 2, 2013 followed by a M2.4 earthquake three days later, all occurring at a depth of five kilometers. The Timpson earthquake activity now has a cyclical rate and a forecast was given to the proper authorities. As a result, the Southern California and Timpson, TX field results led to an improved design and construction of a third prototype antenna. With a loop antenna array, a viable communication system, and continuous monitoring, a full fracture cycle can be established and observed in real-time. In addition, field data could be reviewed quickly for assessment and lead to a much more improved earthquake forecasting capability. The EM precursors determined by this method appear to surpass all prior precursor claims, and the general public will finally receive long overdue forecasting.

  14. An interstellar precursor mission

    NASA Technical Reports Server (NTRS)

    Jaffe, L. D.; Ivie, C.; Lewis, J. C.; Lipes, R. G.; Norton, H. N.; Stearns, J. W.; Stimpson, L.; Weissman, P.

    1977-01-01

    A mission out of the planetary system, with launch about the year 2000, could provide valuable scientific data as well as test some of the technology for a later mission to another star. Primary scientific objectives for the precursor mission concern characteristics of the heliopause, the interstellar medium, stellar distances (by parallax measurements), low energy cosmic rays, interplanetary gas distribution, and mass of the solar system. Secondary objectives include investigation of Pluto. Candidate science instruments are suggested. Individual spacecraft systems for the mission were considered, technology requirements and problem areas noted, and a number of recommendations made for technology study and advanced development. The most critical technology needs include attainment of 50-yr spacecraft lifetime and development of a long-life NEP system.

  15. An interstellar precursor mission

    NASA Technical Reports Server (NTRS)

    Jaffe, L. D.; Ivie, C.; Lewis, J. C.; Lipes, R.; Norton, H. N.; Stearns, J. W.; Stimpson, L. D.; Weissman, P.

    1980-01-01

    A mission out of the planetary system, launched about the year 2000, could provide valuable scientific data as well as test some of the technology for a later mission to another star. Primary scientific objectives for the precursor mission concern characteristics of the heliopause, the interstellar medium, stellar distances (by parallax measurements), low-energy cosmic rays, interplanetary gas distribution, and the mass of the solar system. Secondary objectives include investigation of Pluto. The mission should extend to 400-1000 AU from the sun. A heliocentric hyperbolic escape velocity of 50-100 km/sec or more is needed to attain this distance within a reasonable mission duration (20-50 years). The trajectory should be toward the incoming interstellar gas. For a year 2000 launch, a Pluto encounter and orbiter can be included. A second mission targeted parallel to the solar axis would also be worthwhile. The mission duration is 20 years, with an extended mission to a total of 50 years. A system using one or two stages of nuclear electric propulsion (NEP) was selected as a possible baseline. The most promising alternatives are ultralight solar sails or laser sailing, with the lasers in earth orbit, for example. The NEP baseline design allows the option of carrying a Pluto orbiter as a daughter spacecraft.

  16. PRECURSOR FLARES IN OJ 287

    SciTech Connect

    Pihajoki, P.; Berdyugin, A.; Lindfors, E.; Reinthal, R.; Sillanpaeae, A.; Takalo, L.; Valtonen, M.; Nilsson, K.; Zola, S.; Koziel-Wierzbowska, D.; Liakos, A.; Drozdz, M.; Winiarski, M.; Ogloza, W.; Provencal, J.; Santangelo, M. M. M.; Salo, H.; Chandra, S.; Ganesh, S.; Baliyan, K. S.; and others

    2013-02-10

    We have studied three most recent precursor flares in the light curve of the blazar OJ 287 while invoking the presence of a precessing binary black hole in the system to explain the nature of these flares. Precursor flare timings from the historical light curves are compared with theoretical predictions from our model that incorporate effects of an accretion disk and post-Newtonian description for the binary black hole orbit. We find that the precursor flares coincide with the secondary black hole descending toward the accretion disk of the primary black hole from the observed side, with a mean z-component of approximately z{sub c} = 4000 AU. We use this model of precursor flares to predict that precursor flare of similar nature should happen around 2020.96 before the next major outburst in 2022.

  17. Baclofen for narcolepsy with cataplexy: two cases

    PubMed Central

    Lee, Elliott Kyung; Douglass, Alan Bruce

    2015-01-01

    Narcolepsy is a disabling sleep disorder characterized by daytime hypersomnolence. Those with cataplexy have spells of muscle weakness precipitated by strong emotions, especially laughter or surprise. Cataplexy treatments include antidepressants or a GABA-B agonist, gamma hydroxybutyrate (GHB). GHB is the most effective treatment for cataplexy, but is expensive and can have significant side effects. A recent report of a murine model of narcolepsy-cataplexy suggests R-baclofen has potential efficacy against cataplexy. We report on two narcolepsy patients with multiple daily cataplexy episodes, one of whom had been effectively treated with GHB, but had to discontinue it for unrelated medical reasons. Both subsequently tried baclofen and experienced almost complete resolution of cataplexy. This report suggests baclofen can be an effective treatment for cataplexy in humans and warrants further study. PMID:26251634

  18. Preparation of superconductor precursor powders

    DOEpatents

    Bhattacharya, Raghunath

    1998-01-01

    A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic and/or reduced particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of all metals in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products.

  19. REMOVING TRIHALOMETHANE PRECURSORS BY COAGULATION

    EPA Science Inventory

    The removal of trihalomethane precursors by coagulation was studied with low turbidity, low alkalinity waters containing high levels of aquatic humic matter. Jar tests were conducted with synthetic and natural waters using alum, high-molecular-weight polymers, cationic polymers, ...

  20. Precursors of Hypertension: A Review

    PubMed Central

    Thomas, John; Neser, William B.; Thomas, Johniene; Semenya, Kofi; Green, Donald R.

    1983-01-01

    Recent advances in hypertension therapy have been remarkable; however, much less is known about those precursors that facilitate preventive and early intervention measures. This review of the literature indicates that relevant precursors are early elevated casual systolic blood pressures, positive family history, and obesity in females. Additional predisposing or enhancing factors point to high sodium ingestion, heavy smoking, and high socioecologic stress. Evidence for a high-risk hypertensive personality is not conclusive. There is a paucity of longitudinal data on hypertension in the black population. PMID:6864814

  1. Preparation of superconductor precursor powders

    DOEpatents

    Bhattacharya, R.

    1998-08-04

    A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic and/or reduced particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of all metals in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products. 7 figs.

  2. Preparation of superconductor precursor powders

    DOEpatents

    Bhattacharya, Raghunath; Blaugher, Richard D.

    1995-01-01

    A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals, such as nitrate salts of thallium, barium, calcium, and copper, which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of thallium in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products.

  3. Intermolecular Interactions between Eosin Y and Caffeine Using 1H-NMR Spectroscopy

    PubMed Central

    Okuom, Macduff O.; Wilson, Mark V.; Jackson, Abby; Holmes, Andrea E.

    2014-01-01

    DETECHIP has been used in testing analytes including caffeine, cocaine, and tetrahydrocannabinol (THC) from marijuana, as well as date rape and club drugs such as flunitrazepam, gamma-hydroxybutyric acid (GHB), and methamphetamine. This study investigates the intermolecular interaction between DETECHIP sensor eosin Y (DC1) and the analyte (caffeine) that is responsible for the fluorescence and color changes observed in the actual array. Using 1H-NMR, 1H-COSY, and 1H-DOSY NMR methods, a proton exchange from C-8 of caffeine to eosin Y is proposed. PMID:25018772

  4. The Innate Lymphoid Cell Precursor.

    PubMed

    Ishizuka, Isabel E; Constantinides, Michael G; Gudjonson, Herman; Bendelac, Albert

    2016-05-20

    The discovery of tissue-resident innate lymphoid cell populations effecting different forms of type 1, 2, and 3 immunity; tissue repair; and immune regulation has transformed our understanding of mucosal immunity and allergy. The emerging complexity of these populations along with compounding issues of redundancy and plasticity raise intriguing questions about their precise lineage relationship. Here we review advances in mapping the emergence of these lineages from early lymphoid precursors. We discuss the identification of a common innate lymphoid cell precursor characterized by transient expression of the transcription factor PLZF, and the lineage relationships of innate lymphoid cells with conventional natural killer cells and lymphoid tissue inducer cells. We also review the rapidly growing understanding of the network of transcription factors that direct the development of these lineages. PMID:27168240

  5. Precursor polymer compositions comprising polybenzimidazole

    SciTech Connect

    Klaehn, John R.; Peterson, Eric S.; Orme, Christopher J.

    2015-07-14

    Stable, high performance polymer compositions including polybenzimidazole (PBI) and a melamine-formaldehyde polymer, such as methylated, poly(melamine-co-formaldehyde), for forming structures such as films, fibers and bulky structures. The polymer compositions may be formed by combining polybenzimidazole with the melamine-formaldehyde polymer to form a precursor. The polybenzimidazole may be reacted and/or intertwined with the melamine-formaldehyde polymer to form the polymer composition. For example, a stable, free-standing film having a thickness of, for example, between about 5 .mu.m and about 30 .mu.m may be formed from the polymer composition. Such films may be used as gas separation membranes and may be submerged into water for extended periods without crazing and cracking. The polymer composition may also be used as a coating on substrates, such as metal and ceramics, or may be used for spinning fibers. Precursors for forming such polymer compositions are also disclosed.

  6. Nucleation precursors in protein crystallization

    PubMed Central

    Vekilov, Peter G.; Vorontsova, Maria A.

    2014-01-01

    Protein crystal nucleation is a central problem in biological crystallography and other areas of science, technology and medicine. Recent studies have demonstrated that protein crystal nuclei form within crucial precursors. Here, methods of detection and characterization of the precursors are reviewed: dynamic light scattering, atomic force microscopy and Brownian microscopy. Data for several proteins provided by these methods have demonstrated that the nucleation precursors are clusters consisting of protein-dense liquid, which are metastable with respect to the host protein solution. The clusters are several hundred nanometres in size, the cluster population occupies from 10−7 to 10−3 of the solution volume, and their properties in solutions supersaturated with respect to crystals are similar to those in homogeneous, i.e. undersaturated, solutions. The clusters exist owing to the conformation flexibility of the protein molecules, leading to exposure of hydrophobic surfaces and enhanced intermolecular binding. These results indicate that protein conformational flexibility might be the mechanism behind the metastable mesoscopic clusters and crystal nucleation. Investigations of the cluster properties are still in their infancy. Results on direct imaging of cluster behaviors and characterization of cluster mechanisms with a variety of proteins will soon lead to major breakthroughs in protein biophysics. PMID:24598910

  7. Precursors of Short Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Troja, E.; Rosswog, S.; Gehrels, N.

    2010-01-01

    We carried out a systematic search of precursors on the sample of short GRBs observed by Swift. We found that approx. 8-10% of short GRBs display such early episode of emission. One burst (GRB 090510) shows two precursor events, the former approx.13 s and the latter approx. 0.5 s before the GRB. We did not find any substantial difference between the precursor and the main GRB emission, and between short GRBs with and without precursors. We discuss possible mechanisms to reproduce the observed precursor emission within the scenario of compact object mergers. The implications of our results on quantum gravity constraints are also discussed.

  8. Precursor Lesions of Pancreatic Cancer

    PubMed Central

    Higashi, Michiyo; Yamada, Norishige; Goto, Masamichi

    2008-01-01

    This review article describes morphological aspects, gene abnormalities, and mucin expression profiles in precursor lesions such as pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasm (IPMN), and mucinous cystic neoplasm (MCN) of the pancreas, as well as their relation to pancreatic ductal adenocarcinoma (PDAC). The gene abnormalities in precursors of PDAC are summarized as follows: (1) KRAS mutation and p16/CDKN2A inactivation are early events whose frequencies increase with the dysplasia grade in both PanIN and IPMN; (2) TP53 mutation and SMAD4/DPC4 inactivation are late events observed in PanIN3 or carcinomatous change of IPMN in both PanIN and IPMN, although the frequency of the TP53 mutation is lower in IPMN than in PDAC; and (3) also in MCN, KRAS mutation is an early event whose frequency increases with the dysplasia grade, whereas TP53 mutation and SMAD4/DPC4 inactivation are evident only in the carcinoma. The mucin expression profiles in precursors of PDAC are summarized as follows: (1) MUC1 expression increases with the PanIN grade, and is high in PDAC; (2) the expression pattern of MUC2 differs markedly between the major subtypes of IPMN with different malignancy potentials (i.e., IPMN-intestinal type with MUC2+ expression and IPMN-gastric type with MUC2- expression); (3) MUC2 is not expressed in any grade of PanINs, which is useful for differentiating PanIN from intestinal-type IPMN; (4) de novo expression of MUC4, which appears to increase with the dysplasia grade; and (5) high de novo expression of MUC5AC in all grades of PanINs, all types of IPMN, MCN, and PDAC. PMID:20485640

  9. Weighing in on Adipocyte Precursors

    PubMed Central

    Berry, Ryan; Jeffery, Elise; Rodeheffer, Matthew S.

    2013-01-01

    Obesity, defined as an excessive increase in white adipose tissue (WAT), is a global health epidemic. In obesity, WAT expands by increased adipocyte size (hypertrophy) and number (hyperplasia). The location and cellular mechanisms of WAT expansion greatly affect the pathogenesis of obesity. However, the cellular and molecular mechanisms regulating adipocyte size, number and depot-dependent expansion in vivo remain largely unknown. This perspective summarizes previous work addressing adipocyte number in development and obesity and discusses recent advances in the methodologies, genetic tools, and characterization of in vivo adipocyte precursor cells allowing for directed study of hyperplastic WAT growth in vivo. PMID:24239569

  10. Molecular and polymeric ceramic precursors

    SciTech Connect

    Sneddon, L.G.

    1991-08-01

    The development of new methods for the production of complex materials is one of the most important problems in modern solid state chemistry and materials science. This project is attempting to apply the synthetic principles which have evolved inorganic and organometallic chemistry to the production of technologically important non-oxide ceramics, such as boron nitride, boron carbide and metal borides. Our recent work has now resulted in the production of new polymer systems, including poly(B-vinylborazine), polyvinylpentaborane and polyborazylene, that have proven to be high yield precursors to boron-based ceramic materials. Current work is now directed toward the synthesis of new types of molecular and polymeric boron-containing species and on exploration of the solid state properties of the ceramics that have been produced in these studies.

  11. Molecular and polymeric ceramic precursors

    SciTech Connect

    Sneddon, L.G.

    1992-06-01

    The development of new methods for the production of complex materials is one of the most important problems in modern solid state chemistry and materials science. This project is attempting to apply the synthetic principles which have evolved in inorganic and organometallic chemistry to the production of technologically important non-oxide ceramics, such as boron nitride, boron carbide and metal borides. Recent work has now resulted in the production of new polymer systems, including poly(B-vinylborazine), polyvinylpentaborane and polyborazylene, that have proven to be high yield precursors to boron-based ceramic materials. Current work is now directed toward the synthesis of new types of molecular and polymeric boron-containing species and an exploration of the solid state properties of the ceramics that have been produced in these studies.

  12. Leading time domain seismic precursors

    NASA Astrophysics Data System (ADS)

    Boucouvalas, A. C.; Gkasios, M.; Keskebes, A.; Tselikas, N. T.

    2014-08-01

    The problem of predicting the occurrence of earthquakes is threefold. On one hand it is necessary to predict the date and magnitude of an earthquake, and on the other hand the location of the epicenter. In this work after a brief review of the state of earthquake prediction research, we report on a new leading time precursor for determining time onset of earthquake occurrence. We report the linking between earthquakes of the past with those which happen in the future via Fibonacci, Dual and Lucas numbers (FDL) numbers. We demonstrate it here with two example seed earthquakes at least 100 years old. Using this leading indicator method we can predict significant earthquake events >6.5R, with good accuracy approximately +- 1 day somewhere in the world. From a single seed we produce at least 100 trials simultaneously of which 50% are correct to +- 1day. The indicator is based on Fibonacci, Dual and Lucas numbers (FDL). This result hints that the log periodic FDL numbers are at the root of the understanding of the earthquake mechanism. The theory is based on the assumption that each occurred earthquake discontinuity can be thought of as a generating source of FDL time series. (The mechanism could well be linked to planetary orbits). When future dates are derived from clustering and convergence from previous strong earthquake dates at an FDL time distance, then we have a high probability for an earthquake to occur on that date. We set up a real time system which generates FDL time series from each previous significant earthquake (>7R) and we produce a year to year calendar of high probability earthquake dates. We have tested this over a number of years with considerable success. We have applied this technique for strong (>7R) earthquakes across the globe as well as on a restricted region such as the Greek geographic region where the magnitude is small (>4R-6.5R). In both cases the success of the method is impressive. It is our belief that supplementing this method with other precursors will enhance significantly the prediction of significant earthquakes.

  13. Periodic mesoporous organosilica from zwitterionic precursors.

    PubMed

    El Hankari, Samir; Motos-Pérez, Blanca; Hesemann, Peter; Bouhaouss, Ahmed; Moreau, Joël J E

    2011-06-21

    Mesoporous hybrid silica bearing zwitterionic species were synthesized via template-directed hydrolysis-polycondensation reactions from zwitterionic ammonium sulfonate precursors. The formation of the nanostructured phases involves specific precursor-template interactions. The obtained materials are efficient heterogeneous catalysts in Biginelli reactions. PMID:21559546

  14. Precursors and adjuncts of a lunar base

    NASA Technical Reports Server (NTRS)

    Burke, J. D.

    1988-01-01

    The automated, teleoperated, robotic and human-tended subsystems which will precede and accompany a lunar base program are discussed. The information about lunar conditions that can be provided by such precursors and adjuncts is addressed. The use of precursors and adjuncts for communications and navigation, for safety and survival, for lunar archives, and for entertainment and leisure is examined.

  15. Anorectic activity of prostaglandin precursors.

    PubMed Central

    Doggett, N S; Jawaharlal, K

    1977-01-01

    1 Intraperitoneal and intragastric (i.g.) administration of prostaglandin precursors arachidonic (2 mg, 15 mg/kg, i.p; 30 mg/kg i.g.), linolenic (100 mg/kg i.p.; 200 mg/kg, i.g.) and linoleic (15, 100 mg/kg, i.p.; 100 mg/kg, i.g.) acids to 22 h food-deprived rats inhibits food intake. 2 This anorexia is similar to that induced by prostaglandin F2alpha (1 mg/kg, i.p.). 3 At anorectic doses these fatty acids do not cause pyrexia, in fact arachidonic acid causes hypothermia. 4 Prior treatment with indomethacin (15 mg/kg) and paracetamol (50 mg/kg) specifically reverses the anorexia and the behavioural satiety induced by the three fatty acids, while not affecting prostaglandin F2alpha-induced suppression of food intake. 5 Results of the present experiments suggest that both physiological and pharmacological modification of appetite could be brought about through an effect on prostaglandin generating systems. PMID:890209

  16. Classification of precursors in nanoscale droplets

    NASA Astrophysics Data System (ADS)

    Isele-Holder, Rolf E.; Ismail, Ahmed E.

    2016-04-01

    Molecular precursors, ultrathin films that precede spreading droplets, are still far from being understood, despite intensive study. The inherent microscopic length scales make small-scale experimental techniques and molecular simulation ideal methods to study this phenomenon. Previous work on molecular precursors using nanoscale droplets, however, consistently suffers from incorrect measurement of the dimensions of the precursor film. An alternative method to accurately characterize the precursor film is presented here. In contrast to previous measures, this method (i) allows for easy detection and characterization of precursors and (ii) yields wetting dynamics that agree with experimental observations. Finally, we briefly comment on previous studies whose conclusions may merit reconsideration in light of the present work.

  17. Method of texturing a superconductive oxide precursor

    DOEpatents

    DeMoranville, Kenneth L.; Li, Qi; Antaya, Peter D.; Christopherson, Craig J.; Riley, Jr., Gilbert N.; Seuntjens, Jeffrey M.

    1999-01-01

    A method of forming a textured superconductor wire includes constraining an elongated superconductor precursor between two constraining elongated members placed in contact therewith on opposite sides of the superconductor precursor, and passing the superconductor precursor with the two constraining members through flat rolls to form the textured superconductor wire. The method includes selecting desired cross-sectional shape and size constraining members to control the width of the formed superconductor wire. A textured superconductor wire formed by the method of the invention has regular-shaped, curved sides and is free of flashing. A rolling assembly for single-pass rolling of the elongated precursor superconductor includes two rolls, two constraining members, and a fixture for feeding the precursor superconductor and the constraining members between the rolls. In alternate embodiments of the invention, the rolls can have machined regions which will contact only the elongated constraining members and affect the lateral deformation and movement of those members during the rolling process.

  18. Synthesis and structures of metal chalcogenide precursors

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; Duraj, Stan A.; Eckles, William E.; Andras, Maria T.

    1990-01-01

    The reactivity of early transition metal sandwich complexes with sulfur-rich molecules such as dithiocarboxylic acids was studied. Researchers recently initiated work on precursors to CuInSe2 and related chalcopyrite semiconductors. Th every high radiation tolerance and the high absorption coefficient of CuInSe2 makes this material extremely attractive for lightweight space solar cells. Their general approach in early transition metal chemistry, the reaction of low-valent metal complexes or metal powders with sulfur and selenium rich compounds, was extended to the synthesis of chalcopyrite precursors. Here, the researchers describe synthesis, structures, and and routes to single molecule precursors to metal chalcogenides.

  19. On the difficulties of detecting PP precursors

    NASA Astrophysics Data System (ADS)

    Lessing, Stephan; Thomas, Christine; Saki, Morvarid; Schmerr, Nicholas; Vanacore, Elizabeth

    2015-06-01

    The PP precursors are seismic waves that form from underside reflections of P waves off discontinuities in the upper mantle transition zone (MTZ). These seismic phases are used to map discontinuity topography, sharpness, and impedance contrasts; the resulting structural variations are then often interpreted as evidence for temperature and/or mineralogy variations within the mantle. The PP precursors as well as other seismic phases have been used to establish the global presence of seismic discontinuities at 410 and 660 km depth. Intriguingly, in more than 80 per cent of PP precursor observations the seismic wave amplitudes are significantly weaker than the amplitudes predicted by seismic reference models. Even more perplexing is the observation that 1-5 per cent of all earthquakes (which are 20-25 per cent of earthquakes with clear PP waveforms) do not show any evidence for the PP precursors from the discontinuities even in the presence of well-developed PP waveforms. Non-detections are found in six different data sets consisting of tens to hundreds of events. We use synthetic modelling to examine a suite of factors that could be responsible for the absence of the PP precursors. The take-off angles for PP and the precursors differ by only 1.2-1.5°; thus source-related complexity would affect PP and the precursors. A PP wave attenuated in the upper mantle would increase the relative amplitude of the PP precursors. Attenuation within the transition zone could reduce precursor amplitudes, but this would be a regional phenomenon restricted to particular source receiver geometries. We also find little evidence for deviations from the theoretical travel path of seismic rays expected for scattered arrivals. Factors that have a strong influence include the stacking procedures used in seismic array techniques in the presence of large, interfering phases, the presence of topography on the discontinuities on the order of tens of kilometres, and 3-D lateral heterogeneity in the velocity and density changes with depth across the transition zone. We also compare the observed precursors' amplitudes with seismic models from calculations of phase equilibria and find that a seismic velocity model derived from a pyrolite composition reproduces the data better than the currently available 1-D earth models. This largely owes to the pyrolite models producing a stronger minimum in the reflection coefficient across the epicentral distances where the reduction in amplitudes of the PP precursors is observed. To suppress the precursors entirely in a small subset of earthquakes, other effects, such as localized discontinuity topography and seismic signal processing effects are required in addition to the changed velocity model.

  20. Atomic Layer Deposition from Dissolved Precursors.

    PubMed

    Wu, Yanlin; Döhler, Dirk; Barr, Maïssa; Oks, Elina; Wolf, Marc; Santinacci, Lionel; Bachmann, Julien

    2015-10-14

    We establish a novel thin film deposition technique by transferring the principles of atomic layer deposition (ALD) known with gaseous precursors toward precursors dissolved in a liquid. An established ALD reaction behaves similarly when performed from solutions. "Solution ALD" (sALD) can coat deep pores in a conformal manner. sALD offers novel opportunities by overcoming the need for volatile and thermally robust precursors. We establish a MgO sALD procedure based on the hydrolysis of a Grignard reagent. PMID:26418724

  1. Biochemical Removal of HAP Precursors From Coal

    SciTech Connect

    Olson, G.; Tucker, L.; Richards, J.

    1997-07-01

    This project addresses DOE`s interest in advanced concepts for controlling emissions of air toxics from coal-fired utility boilers. We are determining the feasibility of developing a biochemical process for the precombustion removal of substantial percentages of 13 inorganic hazardous air pollutant (HAP) precursors from coal. These HAP precursors are Sb, As, Be, Cd, Cr, Cl, Co, F, Pb, Hg, Mn, Ni, and Se. Although rapid physical coal cleaning is done routinely in preparation plants, biochemical processes for removal of HAP precursors from coal potentially offer advantages of deeper cleaning, more specificity, and less coal loss. Compared to chemical processes for coal cleaning, biochemical processes potentially offer lower costs and milder process conditions. Pyrite oxidizing bacteria, most notably Thiobacillusferrooxidans, are being evaluated in this project for their ability to remove HAP precursors from U.S. coals.

  2. [Structure and functions of bacterial proteinase precursors].

    PubMed

    Serkina, A V; Shevelev, A B; Chestukhina, G G

    2001-01-01

    The data on the precursors of bacterial proteases were generalized. The structure and special features of processing of the precursors of bacillary subtilisins, the alpha-lytic protease from Lysobacter enzymogenes and the related chymotrypsin-like proteases from Streptomyces griseus, and the metalloproteases from bacilli and Pseudomonas aeruginosa were discussed. The approaches to producing the precursors and the protease propeptides and to in vitro characterizing them were particularly analyzed. The following physiological functions of the propeptides within the protease precursors were considered probable: (a) inhibition of the proteases to protect the host cells from the proteolytic damage; (b) participation in the folding of the mature enzyme; and (c) providing for the protease interaction with the bacterial cell surveillance mechanisms, including protease translocation through the cell wall. PMID:11641907

  3. Synthesis and characterization of preceramic precursors

    SciTech Connect

    Bonilla, I.

    1996-10-01

    The reaction of trichloroborazine with acetylides was investigated and found to result in the formation of potential precursors to ceramics, such as boron nitride (BN) and boron carbide (B{sub 4}C). The synthesis of molecular precursors to these ceramics is important since they will help to solve problems associated with traditional techniques used for the formation of these ceramics, such as coating substrates with suitable precursors to ceramic composites which are soluble in organic solvents. These precursors can find applications in modification of surfaces, studies of interactions between surface and ceramic, and new understanding in the topography and structure of the synthesized material. Conventional synthetic techniques in inorganic chemistry were utilized for the synthesis of these preceramic materials, these include, high vacuum line and bench top chemistry techniques. Partial characterization of the synthesized compounds was achieved by the use of standard characterization techniques in this field, such as multinuclear magnetic resonance experiments, and infrared spectroscopy.

  4. Hydridosiloxanes as precursors to ceramic products

    DOEpatents

    Blum, Y.D.; Johnson, S.M.; Gusman, M.I.

    1997-06-03

    A method is provided for preparing ceramic precursors from hydridosiloxane starting materials and then pyrolyzing these precursors to give rise to silicious ceramic materials. Si-H bonds present in the hydridosiloxane starting materials are catalytically activated, and the activated hydrogen atoms may then be replaced with nonhydrogen substituents. These preceramic materials are pyrolyzed in a selected atmosphere to give the desired ceramic product. Ceramic products which may be prepared by this technique include silica, silicon oxynitride, silicon carbide, metal silicates, and mullite.

  5. Hydridosiloxanes as precursors to ceramic products

    DOEpatents

    Blum, Yigal D.; Johnson, Sylvia M.; Gusman, Michael I.

    1997-01-01

    A method is provided for preparing ceramic precursors from hydridosiloxane starting materials and then pyrolyzing these precursors to give rise to silicious ceramic materials. Si--H bonds present in the hydridosiloxane starting materials are catalytically activated, and the activated hydrogen atoms may then be replaced with nonhydrogen substituents. These preceramic materials are pyrolyzed in a selected atmosphere to give the desired ceramic product. Ceramic products which may be prepared by this technique include silica, silicon oxynitride, silicon carbide, metal silicates, and mullite.

  6. Acoustic precursor wave propagation in viscoelastic media.

    PubMed

    Zhu, Guangran Kevin; Mojahedi, Mohammad; Sarris, Costas D

    2014-03-01

    Precursor field theory has been developed to describe the dynamics of electromagnetic field evolution in causally attenuative and dispersive media. In Debye dielectrics, the so-called Brillouin precursor exhibits an algebraic attenuation rate that makes it an ideal pulse waveform for communication, sensing, and imaging applications. Inspired by these studies in the electromagnetic domain, the present paper explores the propagation of acoustic precursors in dispersive media, with emphasis on biological media. To this end, a recently proposed causal dispersive model is employed, based on its interpretation as the acoustic counterpart of the ColeCole model for dielectrics. The model stems from the fractional stressstrain relation, which is consistent with the empirically known frequency power-law attenuation in viscoelastic media. It is shown that viscoelastic media described by this model, including human blood, support the formation and propagation of Brillouin precursors. The amplitude of these precursors exhibits a sub-exponential attenuation rate as a function of distance, actually being proportional to z(-p), where z is the distance traveled within the medium and 0.5

    precursors identified in this work facilitate the design of optimal waveforms for propagation in complex media, creating new possibilities for acoustic-pulse-based communication and imaging systems. PMID:24569254

  7. Astrocyte Precursor Response to Embryonic Brain Injury

    PubMed Central

    Domowicz, Miriam S.; Henry, Judith G.; Wadlington, Natasha; Navarro, Antonia; Kraig, Richard P.; Schwartz, Nancy B.

    2011-01-01

    Penetrating traumatic insult during pregnancy is a leading cause of human fetal demise; in particular trauma to the brain may lead to devastating long-term cognitive sequelae. Perinatal brain injury involves glial precursors, but the neural mechanisms controlling astrocyte ontogeny after injury remain incompletely understood, partly due to a lack of appropriate markers and animal models. We analyzed astrocyte precursor response to injury at the beginning (E11) and peak (E15) of gliogenesis in an avian tectal model of penetrating embryonic brain trauma, without confounding maternal and sibling effects. At both ages, lateral ventricular dilatation, necrotic foci, periventricular cysts and intraventricular hemorrhages were observed distal to stab wounds two days after a unilateral stab injury to optic tecta. Neuronal (TUBB3) and oligodendrocyte precursor (PLP) markers were down-regulated, even far-removed from the wound site. In contrast, the mature astrocyte marker, GFAP, was up-regulated at the wound site, around necrotic areas and cysts, plus in usual areas of GFAP expression. Increased inflammatory response and apoptotic cell death were also confirmed in the injured tecta. Increased expression of NFIA, SOX9 and GLAST at the wound site and in the ventricular zone (VZ) of the injured tecta indicated an astroglial precursor response. However, cell division increased in the VZ only in early (E11) injury, but not later (E15), indicating that in late injury the astrogliogenesis occurring after acute injury is predominantly due to precursor differentiation rather than precursor proliferation. The inability to replenish the glial precursor pool during the critical period of vulnerability to injury may be an important cause of subsequent developmental abnormalities. PMID:21396923

  8. Polyimide precursors for carbon molecular sieve membranes

    NASA Astrophysics Data System (ADS)

    Geiszler, Vincent Carl

    Carbon molecular sieve (CMS) membranes were produced for gas separations by pyrolyzing an asymmetric hollow fiber composed of a polyimide. Using an industrially obtained precursor fiber, the role of pyrolysis conditions on CMS membrane performance was examined. In order to examine the role of precursor morphology and composition on carbon membrane performance, fibers composed of Matrimidsp°ler 5218 were spun and pyrolyzed. Using vacuum pyrolysis at 550sp°C, a CMS membrane was produced that exhibited permselective performance that was above the "upper bound" for air separations. In order to create "robustness" in the pyrolysis process for potentially "nonideal" fiber morphologies, several processing variables were investigated-pyrolysis in a vacuum versus an inert purge gas, the purge gas flow rate, the type of purge gas, residual oxygen content in the purge gas, and the pyrolysis temperature. The role of the support material was examined and a potential model for precursor pyrolysis was constructed. Utilizing previously studied techniques, asymmetric hollow fibers were spun to create a variety of morphologies and compositions. While some of the fibers could be considered "good" polyimide membranes, some of the fibers would be considered "nonideal". For the precursor morphology and composition studies, certain characteristics were chosen for investigation. Hollow fibers having different inner and outer diameters were produced. The thickness and integrity of the skin layer as well as the overall fiber density were also controlled. The morphology of the fiber substructure was varied. The composition of the fibers was a mixture of the polyimide Matrimidsp°ler 5218 and the epoxy resin F-2300, which have "high" and "low" carbon yields, respectively. Having produced and characterized a variety of precursor fibers, carbon membranes were produced, primarily using a vacuum pyrolysis protocol at 550sp°C. The effects of different precursor fibers compositions, densities, and dimensions on carbon membrane performance were studied. The role of precursor substructure and skin layer morphologies was also examined.

  9. Cockayne syndrome b maintains neural precursor function.

    PubMed

    Sacco, Raffaele; Tamblyn, Laura; Rajakulendran, Nishani; Bralha, Fernando N; Tropepe, Vincent; Laposa, Rebecca R

    2013-02-01

    Neurodevelopmental defects are observed in the hereditary disorder Cockayne syndrome (CS). The gene most frequently mutated in CS, Cockayne Syndrome B (CSB), is required for the repair of bulky DNA adducts in transcribed genes during transcription-coupled nucleotide excision repair. CSB also plays a role in chromatin remodeling and mitochondrial function. The role of CSB in neural development is poorly understood. Here we report that the abundance of neural progenitors is normal in Csb(-/-) mice and the frequency of apoptotic cells in the neurogenic niche of the adult subependymal zone is similar in Csb(-/-) and wild type mice. Both embryonic and adult Csb(-/-) neural precursors exhibited defective self-renewal in the neurosphere assay. In Csb(-/-) neural precursors, self-renewal progressively decreased in serially passaged neurospheres. The data also indicate that Csb and the nucleotide excision repair protein Xpa preserve embryonic neural stem cell self-renewal after UV DNA damage. Although Csb(-/-) neural precursors do not exhibit altered neuronal lineage commitment after low-dose UV (1J/m(2)) in vitro, neurons differentiated in vitro from Csb(-/-) neural precursors that had been irradiated with 1J/m(2) UV exhibited defective neurite outgrowth. These findings identify a function for Csb in neural precursors. PMID:23245699

  10. Radon earthquake precursor: A short review

    NASA Astrophysics Data System (ADS)

    Woith, H.

    2015-05-01

    More than 100 publications reporting radon anomalies to precede earthquakes were evaluated. A clear apparent negative correlation between the number of reported anomalies and the published length of the timeseries is evident. 19% of all timeseries are longer than 5 years, characterized by a precursor rate of less than one precursor per year, the extreme case being 1 anomaly in 18 years of monitoring. Contrary, precursor rates between 1 and more than 10 precursors per year stem from published timeseries shorter than 3 years. Nearly 50% of the timeseries contain exactly one radon anomaly, independent of the length of the observation interval. Generally, the number of anomalies is about 5 times higher at sites where radon is measured in soil air as compared to radon in groundwater. In conclusion: (i) significant radon anomalies exist, and (ii) seismo-tectonically induced radon anomalies probably exist. But, radon anomalies of non-tectonic origin also exist and may look strikingly similar to tectonic ones. Thus, presumably only a fraction of all reported radon precursors are real in the sense that they are physically related to the preparation process of an impending earthquake.

  11. Nozzle designs with pitch precursor ablatives

    NASA Technical Reports Server (NTRS)

    Blevins, H. R.; Bedard, R. J.

    1976-01-01

    Recent developments in carbon phenolic ablatives for solid rocket motor nozzles have yielded a pitch precursor carbon fiber offering significant raw material availability and cost saving advantages as compared to conventional rayon precursor material. This paper discusses the results of an experimental program conducted to assess the thermal performance and characterize the thermal properties of pitch precursor carbon phenolic ablatives. The end result of this program is the complete thermal characterization of pitch fabric, pitch mat, hybrid pitch/rayon fabric and pitch mat molding compound. With these properties determined an analytic capability now exists for predicting the thermal performance of these materials in rocket nozzle liner applications. Further planned efforts to verify material performance and analytical prediction procedures through actual rocket motor firings are also discussed.

  12. Amino acid precursors in lunar samples.

    NASA Technical Reports Server (NTRS)

    Fox, S. W.; Harada, K.; Hare, P. E.

    1972-01-01

    The use of hot water to extract lunar samples, followed by the hydrolysis of the aqueous extract, appears to be the method of choice for identification and quantitation of amino acid precursors in extraterrestrial sources. The net inferences from the analyses to date are (1) that amino acid precursors are verifiably present in lunar dust, and (2) that they are quite certainly not the consequence of contamination by terrestrial organisms, including man. It is suggested that prebiotic evolutionary pathways such as have been traversed on the earth were terminated on the moon for lack of sufficient water. Although some or all of the amino acid precursors may be indigenous, the low level observed suggests that they may also result from onfall of organic compounds from interstellar matter, comets, tails, solar wind, or meteorites.

  13. Sequestration and Transport of Lignin Monomeric Precursors

    SciTech Connect

    Liu, C.J.; Miao, Y.-C.; Zhang, K.-W.

    2011-01-18

    Lignin is the second most abundant terrestrial biopolymer after cellulose. It is essential for the viability of vascular plants. Lignin precursors, the monolignols, are synthesized within the cytosol of the cell. Thereafter, these monomeric precursors are exported into the cell wall, where they are polymerized and integrated into the wall matrix. Accordingly, transport of monolignols across cell membranes is a critical step affecting deposition of lignin in the secondarily thickened cell wall. While the biosynthesis of monolignols is relatively well understood, our knowledge of sequestration and transport of these monomers is sketchy. In this article, we review different hypotheses on monolignol transport and summarize the recent progresses toward the understanding of the molecular mechanisms underlying monolignol sequestration and transport across membranes. Deciphering molecular mechanisms for lignin precursor transport will support a better biotechnological solution to manipulate plant lignification for more efficient agricultural and industrial applications of cell wall biomass.

  14. Precursors prior to type IIn supernova explosions are common: Precursor rates, properties, and correlations

    SciTech Connect

    Ofek, Eran O.; Steinbok, Aviram; Arcavi, Iair; Gal-Yam, Avishay; Tal, David; Ben-Ami, Sagi; Yaron, Ofer; Sullivan, Mark; Shaviv, Nir J.; Kulkarni, Shrinivas R.; Nugent, Peter E.; Kasliwal, Mansi M.; Cenko, S. Bradley; Silverman, Jeffrey M.

    2014-07-10

    There is a growing number of Type IIn supernovae (SNe) which present an outburst prior to their presumably final explosion. These precursors may affect the SN display, and are likely related to poorly charted phenomena in the final stages of stellar evolution. By coadding Palomar Transient Factory (PTF) images taken prior to the explosion, here we present a search for precursors in a sample of 16 Type IIn SNe. We find five SNe IIn that likely have at least one possible precursor event (PTF 10bjb, SN 2010mc, PTF 10weh, SN 2011ht, and PTF 12cxj), three of which are reported here for the first time. For each SN we calculate the control time. We find that precursor events among SNe IIn are common: at the one-sided 99% confidence level, >50% of SNe IIn have at least one pre-explosion outburst that is brighter than 3 × 10{sup 7} L{sub ☉} taking place up to 1/3 yr prior to the SN explosion. The average rate of such precursor events during the year prior to the SN explosion is likely ≳ 1 yr{sup –1}, and fainter precursors are possibly even more common. Ignoring the two weakest precursors in our sample, the precursors rate we find is still on the order of one per year. We also find possible correlations between the integrated luminosity of the precursor and the SN total radiated energy, peak luminosity, and rise time. These correlations are expected if the precursors are mass-ejection events, and the early-time light curve of these SNe is powered by interaction of the SN shock and ejecta with optically thick circumstellar material.

  15. Polymeric precursors for fibers and matrices

    NASA Technical Reports Server (NTRS)

    Hurwitz, Frances I.

    1992-01-01

    Candidate polymeric precursors for ceramic fiber and matrix processing are discussed, with a view to the advantages and disadvantages of this approach relative to existing alternatives. The properties of ceramic products thus derived are noted to strongly depend on the molecular weight and structure of the starting polymer; in particular, the ceramic's composition and morphology are dependent on the character and extent of crosslinking, as well as on the path of pyrolysis. While large and complex structural ceramic components may ultimately be obtainable by these means, the polymer-precursor method is still in its developmental infancy.

  16. Inhibition of 1,4-butanediol metabolism in human liver in vitro.

    PubMed

    Lenz, Daniel; Jübner, Martin; Bender, Katja; Wintermeyer, Annette; Beike, Justus; Rothschild, Markus A; Käferstein, Herbert

    2011-06-01

    The conversion of 1,4-butanediol (1,4-BD) to gamma-hydroxybutyric acid (GHB), a drug of abuse, is most probably catalyzed by alcohol dehydrogenase, and potentially by aldehyde dehydrogenase. The purpose of this study was to investigate the degradation of 1,4-BD in cytosolic supernatant of human liver in vitro, and to verify involvement of the suggested enzymes by means of gas chromatography-mass spectrometry. The coingestion of 1,4-BD and ethanol (EtOH) might cause complex pharmacokinetic interactions in humans. Therefore, the effect of EtOH on 1,4-BD metabolism by human liver was examined in vitro. Additionally, the influence of acetaldehyde (AL), which might inhibit the second step of 1,4-BD degradation, was investigated. In case of a 1,4-BD intoxication, the alcohol dehydrogenase inhibitor fomepizole (4-methylpyrazole, FOM) has been discussed as an antidote preventing the formation of the central nervous system depressing GHB. Besides FOM, we tested pyrazole, disulfiram, and cimetidine as possible inhibitors of the formation of GHB from 1,4-BD catalyzed by human liver enzymes in vitro. The conversion of 1,4-BD to GHB was inhibited competitively by EtOH with an apparent K(i) of 0.56 mM. Therefore, the coingestion of 1,4-BD and EtOH might increase the concentrations and the effects of 1,4-BD itself. By contrast AL accelerated the formation of GHB. All antidotes showed the ability to inhibit the formation of GHB. In comparison FOM showed the highest inhibitory effectiveness. Furthermore, the results confirm strong involvement of ADH in 1,4-BD metabolism by human liver. PMID:21533996

  17. Superconductor precursor mixtures made by precipitation method

    DOEpatents

    Bunker, Bruce C.; Lamppa, Diana L.; Voigt, James A.

    1989-01-01

    Method and apparatus for preparing highly pure homogeneous precursor powder mixtures for metal oxide superconductive ceramics. The mixes are prepared by instantaneous precipitation from stoichiometric solutions of metal salts such as nitrates at controlled pH's within the 9 to 12 range, by addition of solutions of non-complexing pyrolyzable cations, such as alkyammonium and carbonate ions.

  18. SUMMER 1990 ATLANTA OZONE PRECURSOR STUDY

    EPA Science Inventory

    During the summer of 1990, the U.S. Environmental Protection Agency (EPA) conducted a major monitoring study in Atlanta, Georgia, addressing the measurement of ozone and its precursors. The study was undertaken to obtain an information base to support the development and implemen...

  19. Biochemical Removal of HAP Precursors from Coal

    SciTech Connect

    Gregory J. Olson

    1997-05-12

    Column biooxidation tests with Kentucky coal confirmed results of earlier shake flask tests showing significant removal from the coal of arsenic, selenium, cobalt, manganese, nickel and cadmium. Rates of pyrite biooxidation in Kentucky coal were only slightly more than half the rates found previously for Indiana and Pittsburgh coals. Removal of pyrite from Pittsburgh coal by ferric ion oxidation slows markedly as ferrous ions accumulate in solution, requiring maintenance of high redox potentials in processes designed for removal of pyrite and hazardous air pollutant (HAP) precursors by circulation of ferric solutions through coal. The pyrite oxidation rates obtained in these tests were used by Unifield Engineering to support the conceptual designs for alternative pyrite and HAP precursor bioleaching processes for the phase 2 pilot plant. Thermophilic microorganisms were tested to determine if mercury could be mobilized from coal under elevated growth temperatures. There was no evidence for mercury removal from coal under these conditions. However, the activity of the organisms may have liberated mercury physically. It is also possible that the organisms dissolved mercury and it readsorbed to the clay preferentially. Both of these possibilities are undergoing further testing. The Idaho National Engineering and Environmental Laboratory�s (INEEL) slurry column reactor was operated and several batches of feed coal, product coal, waste solids and leach solutions were submitted to LBL for HAP precursor analysis. Results to date indicate significant removal of mercury, arsenic and other HAP precursors in the combined physical-biological process.

  20. ATLANTA OZONE PRECURSOR MONITORING STUDY DATA REPORT

    EPA Science Inventory

    Monitoring was conducted during the summer of 1990 to address the measurement of ozone (0a) and ozone precursors in Atlanta, Georgia. ata was collected using automated gas chromatography. esolved individual species were detected via a flame ionization detector (FID) and an electr...

  1. Basics for Testing Large Earthquake Precursors

    NASA Astrophysics Data System (ADS)

    Romashkova, L. L.; Kossobokov, V. G.; Peresan, A.

    2008-12-01

    Earthquakes, the large or significant ones in particular, are extreme events that, by definition, are the rare ones. Testing candidates to large earthquake precursors implies investigation a small sample of case- histories with the support of specific and sensitive statistical methods and data of different quality, collected in various conditions. Regretfully, in many seismological studies the methods of mathematical statistics are used outside their applicability: earthquakes are evidently not independent events and have heterogeneous, perhaps fractal distribution in space and time. Moreover, the naïve or, conversely, delicately-designed models are considered as a full replacement of seismic phenomena. Although there are many claims of earthquake precursors, most of them should remain in the list of precursor candidates, which have never been tested in any rigorous way, and, in fact, are anecdotal cases of coincidental occurrence. To establish a precursory link between sequences of events of the same or different phenomena, it is necessary to accumulate enough statistics in a rigorous forecast/prediction test, which results, i.e. success-to-failure scores and space-time volume of alarms, must appeal for rejecting hypotheses of random coincidental appearance. We reiterate suggesting to use so-called "Seismic Roulette" null-hypothesis as the most adequate random alternative accounting for the empirical spatial distribution of earthquakes in question and illustrate a few outcomes of Testing Large Earthquake Precursors.

  2. School Violence: Prevalence, Precursors, and Prevention.

    ERIC Educational Resources Information Center

    Juvonen, Jaanna

    2002-01-01

    Reviews types of school violence students confront, including a frequent precursor thereto: bullying. Discusses positive and negative aspects of current approach to school violence prevention such as surveillance, zero-tolerance policies, anti-bullying programs. Describes components of model school violence-prevention program. (Contains 38…

  3. Detection of Chemical Precursors of Explosives

    NASA Technical Reports Server (NTRS)

    Li, Jing

    2012-01-01

    Certain selected chemicals associated with terrorist activities are too unstable to be prepared in final form. These chemicals are often prepared as precursor components, to be combined at a time immediately preceding the detonation. One example is a liquid explosive, which usually requires an oxidizer, an energy source, and a chemical or physical mechanism to combine the other components. Detection of the oxidizer (e.g. H2O2) or the energy source (e.g., nitromethane) is often possible, but must be performed in a short time interval (e.g., 5 15 seconds) and in an environment with a very small concentration (e.g.,1 100 ppm), because the target chemical(s) is carried in a sealed container. These needs are met by this invention, which provides a system and associated method for detecting one or more chemical precursors (components) of a multi-component explosive compound. Different carbon nanotubes (CNTs) are loaded (by doping, impregnation, coating, or other functionalization process) for detecting of different chemical substances that are the chemical precursors, respectively, if these precursors are present in a gas to which the CNTs are exposed. After exposure to the gas, a measured electrical parameter (e.g. voltage or current that correlate to impedance, conductivity, capacitance, inductance, etc.) changes with time and concentration in a predictable manner if a selected chemical precursor is present, and will approach an asymptotic value promptly after exposure to the precursor. The measured voltage or current are compared with one or more sequences of their reference values for one or more known target precursor molecules, and a most probable concentration value is estimated for each one, two, or more target molecules. An error value is computed, based on differences of voltage or current for the measured and reference values, using the most probable concentration values. Where the error value is less than a threshold, the system concludes that the target molecule is likely. Presence of one, two, or more target molecules in the gas can be sensed from a single set of measurements.

  4. Electromagnetic Whistler Precursors at Supercritical Interplanetary Shocks

    NASA Technical Reports Server (NTRS)

    Wilson, L. B., III

    2012-01-01

    We present observations of electromagnetic precursor waves, identified as whistler mode waves, at supercritical interplanetary shocks using the Wind search coil magnetometer. The precursors propagate obliquely with respect to the local magnetic field, shock normal vector, solar wind velocity, and they are not phase standing structures. All are right-hand polarized with respect to the magnetic field (spacecraft frame), and all but one are right-hand polarized with respect to the shock normal vector in the normal incidence frame. Particle distributions show signatures of specularly reflected gyrating ions, which may be a source of free energy for the observed modes. In one event, we simultaneously observe perpendicular ion heating and parallel electron acceleration, consistent with wave heating/acceleration due to these waves.

  5. Nonlinear magnetohydrodynamics of edge localized mode precursors

    SciTech Connect

    Guo, Z. B.; Wang, Lu; Wang, X. G.

    2015-02-15

    A possible origin of edge-localized-mode (ELM) precursors based on nonlinear ideal peeling-ballooning mode is reported. Via nonlinear variational principle, a nonlinear evolution equation of the radial displacement is derived and solved, analytically. Besides an explosive growth in the initial nonlinear phase, it is found that the local displacement evolves into an oscillating state in the developed nonlinear phase. The nonlinear frequency of the ELM precursors scales as ω{sub pre}∼x{sup 1/3}ξ{sup ^}{sub ψ,in}{sup 2/3}n, with x position in radial direction, ξ{sup ^}{sub ψ,in} strength of initial perturbation, and n toroidal mode number.

  6. Metabolic Precursors to Amphetamine and Methamphetamine.

    PubMed

    Cody, J D

    1993-12-01

    Analysis and interpretation of amphetamine results is a challenging process made difficult by a number of factors. One of the complications comes from determination of the origin of amphetamine or methamphetamine in a sample. Given the relatively rare occasions that either of these two drugs are prescribed, legal prescription of one of these drugs is seldom a reason for positive findings. A number of other precursor compounds are metabolized by the body to amphetamine or methamphetamine, many of which could be used for legitimate reasons. Fourteen different metabolic precursors of amphetamine or methamphetamine are included in this review. They are amphetaminil, benzphetamine, clobenzorex, deprenyl, dimethylamphetamine, ethylamphetamine, famprofazone, fencamine, fenethylline, fenproporex, furfenorex, mefenorex, mesocarb, and prenylamine. Medical use, metabolism, analysis, and interpretation are described to afford sufficient information to evaluate the possible involvement of these drugs in positive amphetamine or methamphetamine results. PMID:26270078

  7. A Novel Synthesis of Biomolecular Precursors

    NASA Astrophysics Data System (ADS)

    Saladino, Raffaele; et al.

    2004-07-01

    We discuss the role of formamide, a product of hydrolysis of hydrogen cyanide (HCN), as precursor of relevant components of nucleic acids in prebiotic conditions and describe the efficient synthesis of purine, adenine, cytosine, thymine, and 5-hydroxymethyluracil. The remarkable formation of some purine acyclonucleosides is also reported, providing a possible solution to the problem of the elusive origin of nucleosides under prebiotic conditions. The role of catalysts as CaCO3, silica, alumina, TiO2 and others in enhancing and variegating the yields of these compounds is described. In addition, formamide acts as a selective agent in the degradation of bases, nucleosides and DNA oligomers. Taken together, these observations reveal a formamide-based synthesis/degradation cycle whose properties provide an equilibration mechanism for the pool of prebiotic precursors.

  8. [Presentation of the Lunar Precursor Robotics Program

    NASA Technical Reports Server (NTRS)

    Lavoie, Anthony R.

    2008-01-01

    The Lunar Precursor Robotics Program (LPRP) is the host program for the Exploration Systems Mission Directorate's (ESMD) lunar robotic precursor missions to the Moon. The program includes two missions, the Lunar Reconnaissance Orbiter (LRO), and the Lunar CRater Observation and Sensing Satellite (LCROSS). Both missions will provide the required lunar information to support development and operations of those systems required for Human lunar return. LPRP is developing a lunar mapping plan, Called the Lunar Mapping and Modeling Project, to create the capability to archive and present all data from LRO, LCROSS, historical lunar missions, and international lunar missions for future mission planning and operations. LPRP is also developing its educational and public outreach activities for the Vision for Space Exploration's first missions. LPRP is working closely with the Science Mission Directorate as their lunar activities come into focus.

  9. Precursors to radiopharmaceutical agents for tissue imaging

    DOEpatents

    Srivastava, Prem C.; Knapp, Jr., Furn F.

    1988-01-01

    A class of radiolabeled compounds to be used in tissue imaging that exhibits rapid brain uptake, good brain:blood radioactivity ratios, and long retention times. The imaging agents are more specifically radioiodinated aromatic amines attached to dihydropyridine carriers, that exhibit heart as well as brain specificity. In addition to the radiolabeled compounds, classes of compounds are also described that are used as precursors and intermediates in the preparation of the imaging agents.

  10. Cellular Kinetics of Perivascular MSC Precursors

    PubMed Central

    Chen, William C. W.; Murray, Iain R.; Lazzari, Lorenza; Huard, Johnny; Péault, Bruno

    2013-01-01

    Mesenchymal stem/stromal cells (MSCs) and MSC-like multipotent stem/progenitor cells have been widely investigated for regenerative medicine and deemed promising in clinical applications. In order to further improve MSC-based stem cell therapeutics, it is important to understand the cellular kinetics and functional roles of MSCs in the dynamic regenerative processes. However, due to the heterogeneous nature of typical MSC cultures, their native identity and anatomical localization in the body have remained unclear, making it difficult to decipher the existence of distinct cell subsets within the MSC entity. Recent studies have shown that several blood-vessel-derived precursor cell populations, purified by flow cytometry from multiple human organs, give rise to bona fide MSCs, suggesting that the vasculature serves as a systemic reservoir of MSC-like stem/progenitor cells. Using individually purified MSC-like precursor cell subsets, we and other researchers have been able to investigate the differential phenotypes and regenerative capacities of these contributing cellular constituents in the MSC pool. In this review, we will discuss the identification and characterization of perivascular MSC precursors, including pericytes and adventitial cells, and focus on their cellular kinetics: cell adhesion, migration, engraftment, homing, and intercellular cross-talk during tissue repair and regeneration. PMID:24023546

  11. Laboratory Study of Shock Wave Precursors

    NASA Astrophysics Data System (ADS)

    Burris, R.; Grun, J.; Manka, C.; Fisher, A.; Evans, K.

    1996-11-01

    When a shock wave propagates over a heated layer of gas, the shock wave will refract and its velocity will increase. A precursor shock wave will form which precedes the original shock wave along the surface. A highly structured, complicated vortex flow region develops under the precursor shock wave which can result in greatly enhanced dynamic pressure conditions. We report here on a laboratory experimental simulation of the phenomenon. A shock wave in 1 atm. of Argon is generated by focusing the NRL Pharos III Laser (1.5 kJ, 5 nsec, 1054 nm) through an evacuated path onto a thin metal foil at the gas/vacuum interface. The shock wave spherically expands over a thin heated layer above a 5cm by 5cm tantalum foil which was preheated up to 3000K (corresponding to > 3x sound speed at room temperature) with a fast rise-time current pulse (> 50 ?sec). The formation, propagation, and cleanup (or decay) of the shock wave precursor, caused by the thin layer of hot gas on the foil surface, was studied with a combined folded-wave interferometry/dark-field shadowgraphy diagnostic. The results of these experiments will be presented.

  12. Formulating Precursors for Coating Metals and Ceramics

    NASA Technical Reports Server (NTRS)

    Morales, Wilfredo; Gatica, Jorge E.; Reye, John T.

    2005-01-01

    A protocol has been devised for formulating low-vapor-pressure precursors for protective and conversion coatings on metallic and ceramic substrates. The ingredients of a precursor to which the protocol applies include additives with phosphate esters, or aryl phosphate esters in solution. Additives can include iron, chromium, and/or other transition metals. Alternative or additional additives can include magnesium compounds to facilitate growth of films on substrates that do not contain magnesium. Formulation of a precursor begins with mixing of the ingredients into a high-vapor-pressure solvent to form a homogeneous solution. Then the solvent is extracted from the solution by evaporation - aided, if necessary, by vacuum and/or slight heating. The solvent is deemed to be completely extracted when the viscosity of the remaining solution closely resembles the viscosity of the phosphate ester or aryl phosphate ester. In addition, satisfactory removal of the solvent can be verified by means of a differential scanning calorimetry essay: the absence of endothermic processes for temperatures below 150 C would indicate that the residual solvent has been eliminated from the solution beyond a detectable dilution level.

  13. Scalar model for frictional precursors dynamics

    NASA Astrophysics Data System (ADS)

    Taloni, Alessandro; Benassi, Andrea; Sandfeld, Stefan; Zapperi, Stefano

    2015-02-01

    Recent experiments indicate that frictional sliding occurs by nucleation of detachment fronts at the contact interface that may appear well before the onset of global sliding. This intriguing precursory activity is not accounted for by traditional friction theories but is extremely important for friction dominated geophysical phenomena as earthquakes, landslides or avalanches. Here we simulate the onset of slip of a three dimensional elastic body resting on a surface and show that experimentally observed frictional precursors depend in a complex non-universal way on the sample geometry and loading conditions. Our model satisfies Archard's law and Amontons' first and second laws, reproducing with remarkable precision the real contact area dynamics, the precursors' envelope dynamics prior to sliding, and the normal and shear internal stress distributions close to the interfacial surface. Moreover, it allows to assess which features can be attributed to the elastic equilibrium, and which are attributed to the out-of-equilibrium dynamics, suggesting that precursory activity is an intrinsically quasi-static physical process. A direct calculation of the evolution of the Coulomb stress before and during precursors nucleation shows large variations across the sample, explaining why earthquake forecasting methods based only on accumulated slip and Coulomb stress monitoring are often ineffective.

  14. Scalar model for frictional precursors dynamics

    PubMed Central

    Taloni, Alessandro; Benassi, Andrea; Sandfeld, Stefan; Zapperi, Stefano

    2015-01-01

    Recent experiments indicate that frictional sliding occurs by nucleation of detachment fronts at the contact interface that may appear well before the onset of global sliding. This intriguing precursory activity is not accounted for by traditional friction theories but is extremely important for friction dominated geophysical phenomena as earthquakes, landslides or avalanches. Here we simulate the onset of slip of a three dimensional elastic body resting on a surface and show that experimentally observed frictional precursors depend in a complex non-universal way on the sample geometry and loading conditions. Our model satisfies Archard's law and Amontons' first and second laws, reproducing with remarkable precision the real contact area dynamics, the precursors' envelope dynamics prior to sliding, and the normal and shear internal stress distributions close to the interfacial surface. Moreover, it allows to assess which features can be attributed to the elastic equilibrium, and which are attributed to the out-of-equilibrium dynamics, suggesting that precursory activity is an intrinsically quasi-static physical process. A direct calculation of the evolution of the Coulomb stress before and during precursors nucleation shows large variations across the sample, explaining why earthquake forecasting methods based only on accumulated slip and Coulomb stress monitoring are often ineffective. PMID:25640079

  15. Scalar model for frictional precursors dynamics.

    PubMed

    Taloni, Alessandro; Benassi, Andrea; Sandfeld, Stefan; Zapperi, Stefano

    2015-01-01

    Recent experiments indicate that frictional sliding occurs by nucleation of detachment fronts at the contact interface that may appear well before the onset of global sliding. This intriguing precursory activity is not accounted for by traditional friction theories but is extremely important for friction dominated geophysical phenomena as earthquakes, landslides or avalanches. Here we simulate the onset of slip of a three dimensional elastic body resting on a surface and show that experimentally observed frictional precursors depend in a complex non-universal way on the sample geometry and loading conditions. Our model satisfies Archard's law and Amontons' first and second laws, reproducing with remarkable precision the real contact area dynamics, the precursors' envelope dynamics prior to sliding, and the normal and shear internal stress distributions close to the interfacial surface. Moreover, it allows to assess which features can be attributed to the elastic equilibrium, and which are attributed to the out-of-equilibrium dynamics, suggesting that precursory activity is an intrinsically quasi-static physical process. A direct calculation of the evolution of the Coulomb stress before and during precursors nucleation shows large variations across the sample, explaining why earthquake forecasting methods based only on accumulated slip and Coulomb stress monitoring are often ineffective. PMID:25640079

  16. Bioconversion of proposed precursors into theobroxide and related compounds.

    PubMed

    Li, Peng; Takahashi, Kosaku; Elkhateeb, Ahmed; Matsuura, Hideyuki; Yoshihara, Teruhiko; Nabeta, Kensuke

    2011-12-01

    We have previously reported a tetraketide origin for theobroxide and its related compound. In the present study, bioconversion of natural and deuterium-labeled precursors of this proposed biosynthetic pathway by Lasiodipoldia theobromae was investigated. Theobroxide was quantified after bioconversion from each proposed precursor. The transformation of the isotopically labeled precursor to products was tracked by 2H NMR measurement. PMID:22312709

  17. 40 CFR 766.38 - Reporting on precursor chemical substances.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Reporting on precursor chemical... SUBSTANCES CONTROL ACT DIBENZO-PARA-DIOXINS/DIBENZOFURANS Specific Chemical Testing/Reporting Requirements § 766.38 Reporting on precursor chemical substances. (a) Identification of precursor chemical...

  18. 40 CFR 766.38 - Reporting on precursor chemical substances.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Reporting on precursor chemical... SUBSTANCES CONTROL ACT DIBENZO-PARA-DIOXINS/DIBENZOFURANS Specific Chemical Testing/Reporting Requirements § 766.38 Reporting on precursor chemical substances. (a) Identification of precursor chemical...

  19. 40 CFR 766.38 - Reporting on precursor chemical substances.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Reporting on precursor chemical... SUBSTANCES CONTROL ACT DIBENZO-PARA-DIOXINS/DIBENZOFURANS Specific Chemical Testing/Reporting Requirements § 766.38 Reporting on precursor chemical substances. (a) Identification of precursor chemical...

  20. 40 CFR 766.38 - Reporting on precursor chemical substances.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Reporting on precursor chemical... SUBSTANCES CONTROL ACT DIBENZO-PARA-DIOXINS/DIBENZOFURANS Specific Chemical Testing/Reporting Requirements § 766.38 Reporting on precursor chemical substances. (a) Identification of precursor chemical...

  1. Effects of monocarboxylate transporter inhibition on the oral toxicokinetics/toxicodynamics of γ-hydroxybutyrate and γ-butyrolactone.

    PubMed

    Morse, Bridget L; Morris, Marilyn E

    2013-04-01

    Respiratory depression and death secondary to respiratory arrest have occurred after oral overdoses of γ-hydroxybutyrate (GHB) and its precursor γ-butyrolactone (GBL). GHB is a substrate for monocarboxylate transporters (MCTs), and increasing GHB renal clearance or decreasing GHB absorption via MCT inhibition represents a potential treatment strategy for GHB/GBL overdose. In these studies, GHB and GBL were administered in doses of 1.92, 5.77, and 14.4 mmol/kg orally with and without MCT inhibition to determine effects of this treatment strategy on the oral toxicokinetics and toxicodynamics of GHB and GBL. The competitive MCT inhibitor l-lactate was administered by intravenous infusion starting 1 hour after GHB and GBL administration. Oral administration of l-lactate and the MCT inhibitor luteolin was also evaluated. Respiratory depression was measured using plethysmography. Intravenous l-lactate, but not oral treatments, significantly increased GHB renal and/or oral clearances. At the low dose of GHB and GBL, i.v. l-lactate increased GHB renal clearance. Due to the increased contribution of renal clearance to total clearance at the moderate dose, increased renal clearance translated to an increase in oral clearance. At the highest GHB dose, oral clearance was increased without a significant change in renal clearance. The lack of effect of i.v. l-lactate on renal clearance after a high oral GHB dose suggests possible effects of i.v. l-lactate on MCT-mediated absorption. The resulting increases in oral clearance improved respiratory depression. Intravenous l-lactate also reduced mortality with the high GBL dose. These data indicate i.v. l-lactate represents a potential treatment strategy in oral overdose of GHB and GBL. PMID:23392755

  2. Systems and methods for detection of blowout precursors in combustors

    DOEpatents

    Lieuwen, Tim C.; Nair, Suraj

    2006-08-15

    The present invention comprises systems and methods for detecting flame blowout precursors in combustors. The blowout precursor detection system comprises a combustor, a pressure measuring device, and blowout precursor detection unit. A combustion controller may also be used to control combustor parameters. The methods of the present invention comprise receiving pressure data measured by an acoustic pressure measuring device, performing one or a combination of spectral analysis, statistical analysis, and wavelet analysis on received pressure data, and determining the existence of a blowout precursor based on such analyses. The spectral analysis, statistical analysis, and wavelet analysis further comprise their respective sub-methods to determine the existence of blowout precursors.

  3. Neutron-powered precursors of kilonovae

    NASA Astrophysics Data System (ADS)

    Metzger, Brian D.; Bauswein, Andreas; Goriely, Stephane; Kasen, Daniel

    2015-01-01

    The merger of binary neutron stars (NSs) ejects a small quantity of neutron-rich matter, the radioactive decay of which powers a day to week long thermal transient known as a kilonova. Most of the ejecta remains sufficiently dense during its expansion that all neutrons are captured into nuclei during the r-process. However, recent general relativistic merger simulations by Bauswein and collaborators show that a small fraction of the ejected mass (a few per cent, or 10-4 M?) expands sufficiently rapidly for most neutrons to avoid capture. This matter originates from the shocked-heated interface between the merging NSs. Here, we show that the ?-decay of these free neutrons in the outermost ejecta powers a `precursor' to the main kilonova emission, which peaks on a time-scale of few hours following merger at U-band magnitude 22 (for an assumed distance of 200 Mpc). The high luminosity and blue colours of the neutron precursor render it a potentially important counterpart to the gravitational wave source, that may encode valuable information on the properties of the merging binary (e.g. NS-NS versus NS-black hole) and the NS equation of state. Future work is necessary to assess the robustness of the fast-moving ejecta and the survival of free neutrons in the face of neutrino absorptions, although the precursor properties are robust to a moderate amount of leptonization. Our results provide additional motivation for short latency gravitational wave triggers and rapid follow-up searches with sensitive ground-based telescopes.

  4. Amyloid precursor protein and neural development.

    PubMed

    Nicolas, Maya; Hassan, Bassem A

    2014-07-01

    Interest in the amyloid precursor protein (APP) has increased in recent years due to its involvement in Alzheimer's disease. Since its molecular cloning, significant genetic and biochemical work has focused on the role of APP in the pathogenesis of this disease. Thus far, however, these studies have failed to deliver successful therapies. This suggests that understanding the basic biology of APP and its physiological role during development might be a crucial missing link for a better comprehension of Alzheimer's disease. Here, we present an overview of some of the key studies performed in various model organisms that have revealed roles for APP at different stages of neuronal development. PMID:24961795

  5. On Verification of Earthquake Precursors (Invited)

    NASA Astrophysics Data System (ADS)

    Kossobokov, V. G.

    2009-12-01

    Although there are many claims of earthquake precursors, most of them should remain in the list of precursor candidates, which have never been tested in any rigorous way, and, in fact, are anecdotal cases of coincidental occurrence. To establish a precursory link between sequences of events of the same or different phenomena, it is necessary to accumulate enough statistics in a rigorous forecast/prediction test, which results, i.e. success-to-failure scores and space-time volume of alarms, must appeal for rejecting hypotheses of random coincidental appearance. We reiterate suggesting so-called “Seismic Roulette” null-hypothesis as the most adequate random alternative accounting for the empirical spatial distribution of earthquakes in question: (i) Consider a roulette wheel with as many sectors as the number of earthquake locations from a sample catalog, a sector per each location and (ii) make your bet according to prediction (i.e., determine, which locations are inside area of alarm, and put one chip in each of the corresponding sectors); (iii) Nature turns the wheel; (iv) accumulate statistics of wins and losses along with the number of chips spent. If a precursor in charge of prediction exposes an imperfection of Seismic Roulette then, having in mind optional “antipodal strategy”, one can make the predictions efficient, so that the wins will systematically outscore the losses. Sounds easy, we know! Seismology is juvenile and its appropriate statistical tools to-date may have a "medieval flavor" for those who hurry up to apply a fuzzy language of a highly developed probability theory and consider delicately-designed models as a full replacement of seismic phenomena. To become "quantitatively probabilistic" earthquake forecasts/predictions must be defined with a scientific accuracy. Following the most popular objectivists' viewpoint on probability, we cannot claim "probabilities" adequate without a long series of "yes/no" forecast/prediction outcomes. Without "antiquated binary language" of "yes/no" certainty we cannot judge an outcome ("success/failure"), and, therefore, quantify objectively a forecast/prediction method performance. The paper illustrates the complexity of seismic statistics based on a twenty years of experimental earthquake prediction in real time of extreme seismic events on the global and regional scales, along with a few outcomes of independent testing of earthquake precursors.

  6. Molecular Motion in a Spreading Precursor Film

    NASA Astrophysics Data System (ADS)

    Xu, Hui; Shirvanyants, David; Beers, Kathryn; Matyjaszewski, Krzysztof; Rubinstein, Michael; Sheiko, Sergei S.

    2004-11-01

    Spreading of a polymer drop on a solid substrate was monitored with molecular resolution. Three characteristic rates, i.e., the spreading rate of the precursor film Dspread=(3.9±0.2)×103 nm2/s, the flow-induced diffusion rate of molecules within the film Dinduced=1.3±0.1 nm2/s, and the thermal diffusion coefficient of single molecules Dtherm≤0.10±0.03 nm2/s, were independently measured. Since Dspread≫Dinduced, the plug flow of polymer chains was identified as the main mass-transport mechanism of spreading with an insignificant contribution from the molecular diffusion.

  7. The Mars 2001 Athena Precursor Experiment (APEX)

    NASA Astrophysics Data System (ADS)

    Squyres, S. W.; Arvidson, R.; Bell, J. F., III; Carr, M.; Christensen, P.; Des Marais, D.; D'Uston, C.; Economou, T.; Gorevan, S.; Klingelhöfer, G.; Haskin, L.; Herkenhoff, K.; Knoll, A.; Knudsen, J. M.; Lane, A. L.; Linkin, V.; Malin, M.; McSween, H.; Morris, R.; Rieder, R.; Sims, M.; Soderblom, L.; Wänke, H.; Wdowiak, T.

    1999-01-01

    The Athena Precursor Experiment (APEX) is a suite of scientific instruments for the Mars Surveyor Program 2001 (MSP'01) lander. The major elements of the APEX pay load are: (1) Pancam/Mini-TES, a combined stereo color imager and mid-infrared point spectrometer. (2) An Alpha-Proton-X-Ray Spectrometer (APXS) for in-situ elemental analysis. (3) A Mossbauer Spectrometer for in-situ determination of the mineralogy of Fe-bearing rocks and soils. (4) A Magnet Array that can separate magnetic soil particles from non-magnetic ones.

  8. Amyloid precursor protein: more than just neurodegeneration

    PubMed Central

    2011-01-01

    Amyloid precursor protein (APP) fascinates cell biologists because it is proteolytically processed to generate multiple peptides, including amyloid-β, which is implicated in Alzheimer's disease. However, a large body of data also shows that the extracellular soluble fragment of APP produced by α-secretase (sAPPα) is neuroprotective and promotes neuronal outgrowth. A study by Demars and colleagues appearing in the previous issue provides data showing that sAPPα is a general growth factor for stem cells of multiple lineages. Thus, APP seems to play complex and disparate roles in neurodegeneration and neuroprotection. PMID:22000643

  9. Ballooning instability precursors to high {beta} disruptions

    SciTech Connect

    Fredrickson, E.D.; McGuire, K.M.; Chang, Z.Y.

    1995-12-01

    Strongly ballooning modes have been found as precursors to high {beta} disruptions on TFTR. The modes are typically localized to a region spanning about 60{degree} in the toroidal direction. The toroidal localization is associated with lower frequency, global Magneto-Hydro-Dynamic (MHD) activity, typically an ideal n = 1 kink mode. They have moderate to high frequency (f = 10--20 f{sub rot}), implying toroidal mode numbers in the range n = 10--20. The growth rates for the modes are large, of order 10{sup 4}/sec.

  10. Effects of detergents on ribosomal precursor subunits of Bacillus megaterium.

    PubMed

    Body, A; Brownstein, B H

    1978-01-01

    Cell extracts prepared by osmotic lysis of protoplasts were analyzed by sucrose gradient sedimentation. In the absence of detergents, ribosomal precursor particles were found in a gradient fraction which sedimented faster than mature 50S subunits and in two other fractions coincident with mature 50S and 30S ribosomal subunits. Phospholipid, an indicator of membrane, was shown to be associated with only the fastest-sedimenting ribosomal precursor particle fraction. After the extracts were treated with detergents, all phospholipid was found at the top of the gradients. Brij 58, Triton X-100, and Nonidet P-40 did not cause a change in the sedimentation values of precursors; however, the detergents deoxycholate or LOC (Amway Corp.) disrupted the fastest-sedimenting precursor and converted the ribosomal precursor subunits which sedimented at the 50S and 30S positions to five different classes of more slowly sedimenting particles. Earlier reports on the in vivo assembly of ribosomal subunits have shown that several stages of ribosomal precursor subunits exist, and, in the presence of the detergents deoxycholate and LOC, which had been used to prepare cell extracts, the precursors sedimented more slowly. Our data are consistent with the hypothesis that those detergents selectively modify the structure of ribosomal precursors and lend further support to the hypothesis that the in vivo ribosomal precursor subunits have 50S and 30S sedimentation values. In addition, these data support the idea that the ribosomal precursor particles found in the fast-sedimenting fraction may constitute a unique precursor fraction. PMID:412833

  11. Effects of Detergents on Ribosomal Precursor Subunits of Bacillus megaterium

    PubMed Central

    Body, Barbara A.; Brownstein, Bernard H.

    1978-01-01

    Cell extracts prepared by osmotic lysis of protoplasts were analyzed by sucrose gradient sedimentation. In the absence of detergents, ribosomal precursor particles were found in a gradient fraction which sedimented faster than mature 50S subunits and in two other fractions coincident with mature 50S and 30S ribosomal subunits. Phospholipid, an indicator of membrane, was shown to be associated with only the fastest-sedimenting ribosomal precursor particle fraction. After the extracts were treated with detergents, all phospholipid was found at the top of the gradients. Brij 58, Triton X-100, and Nonidet P-40 did not cause a change in the sedimentation values of precursors; however, the detergents deoxycholate or LOC (Amway Corp.) disrupted the fastest-sedimenting precursor and converted the ribosomal precursor subunits which sedimented at the 50S and 30S positions to five different classes of more slowly sedimenting particles. Earlier reports on the in vivo assembly of ribosomal subunits have shown that several stages of ribosomal precursor subunits exist, and, in the presence of the detergents deoxycholate and LOC, which had been used to prepare cell extracts, the precursors sedimented more slowly. Our data are consistent with the hypothesis that those detergents selectively modify the structure of ribosomal precursors and lend further support to the hypothesis that the in vivo ribosomal precursor subunits have 50S and 30S sedimentation values. In addition, these data support the idea that the ribosomal precursor particles found in the fast-sedimenting fraction may constitute a unique precursor fraction. PMID:412833

  12. The development of autonomy and superego precursors.

    PubMed

    Blum, E J; Blum, H P

    1990-01-01

    Superego precursors appear in the latter part of the first year, concomitant with the behavioural control necessitated and made possible by ego development, particularly of intentionality, communication, and mobility. During the second year of life wilful strivings intensify, complicated by the power struggles of the rapprochement crisis. A subtle process of negotiation accompanies the learning of parental rules and regulations, and the infant also learns that some rules and limits are non-negotiable. The development of the superego depends not only on 'identification with the aggressor' and self-directed aggression, but on positive identifications and internalizations of approval. While the real attitudes of the caregiver are communicated and are important, superego precursors, because of the infant's drives, defences, and ego immaturity, may be far removed from the reality of the caregiver's attitudes and intent. The parents' and infants' inter-identifications and empathy for each other contribute to the capacity for self-criticism, guilt, and remorse, attributes of the developing superego. PMID:2074146

  13. Precursor solitons in a flowing complex plasma

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, Pintu; Jaiswal, Surabhi; Sen, Abhijit

    2015-11-01

    We report the first experimental observation of precursor solitons in a flowing dusty plasma. The nonlinear solitary dust acoustic waves (DAWs) are excited by a supersonic mass flow of the dust particles passing over an electrostatic potential hill. In a frame where the fluid is stationary and the hill is moving the solitons propagate in the upstream direction while wake structures consisting of linear DAWs are seen to propagate in the downstream direction. The experiments have been carried out in a U-shaped Dusty Plasma Experimental (DPEx) device where kaolin particles are immersed in a DC discharge argon plasma to form the dusty plasma and a floating wire mounted on the cathode creates a potential hill. The dust flow is induced by sudden changes in the hill height and the solitary structures are seen only for supersonic flows and up to an upper limit of the flow. A theoretical model description of the phenomenon will be provided and some practical implications of such precursor excitations for a charged object moving in a plasma will be discussed.

  14. Diagenesis and catagenesis of marine kerogen precursors

    SciTech Connect

    Rafalska-Bloch, J.

    1987-01-01

    The approaches used were (1) investigations of marine kerogen precursors in a natural environment, e.g., in reefal carbonate sediments (in Puerto Rico and Belize) and (2) laboratory modeling of the condensation of marine kerogen precursors, i.e., amino acids and sugars and subsequent formation and reactions of melanoidin polymers. The organic facies model of a reef environment was developed from the analysis of (1) total organic carbon, (2) visual protokerogen types, (3) Rock-Eval indices and (4) sedimentological considerations. Rates of melanoidin formation, incorporation of amino acid and glucose into the melanoidin polymers and their attendant decrease in the melanoidin solutions were evaluated. The observed pattern was that of initially rapid loss of biomonomers from the melanoidin solutions and concomitant formation of melanoidin polymers. The rate of incorporation of amino acids into the polymers is related partly to glucose concentration and partly to the type of amino acid. The racemization rates of amino acids were also investigated. During the course of melanoidin formation the original amino acid abundances and stereochemistry are redistributed during simulated diagenesis. This may have implications for natural environments where diagenesis may obscure the original depositional signal and complicate geochronological studies. Catagenetic evolution of both synthetic geopolymer (lysine, histidine, arginine, glucose - melanoidin) and natural geopolymers (Belizian organic matter) was simulated using hydrous pyrolysis.

  15. Design of Aerosol Coating Reactors: Precursor Injection.

    PubMed

    Buesser, Beat; Pratsinis, Sotiris E

    2011-12-21

    Particles are coated with thin shells to facilitate their processing and incorporation into liquid or solid matrixes without altering core particle properties (coloristic, magnetic, etc.). Here, computational fluid and particle dynamics are combined to investigate the geometry of an aerosol reactor for continuous coating of freshly-made titanium dioxide core nanoparticles with nanothin silica shells by injection of hexamethyldisiloxane (HMDSO) vapor downstream of TiO2 particle formation. The focus is on the influence of HMDSO vapor jet number and direction in terms of azimuth and inclination jet angles on process temperature and coated particle characteristics (shell thickness and fraction of uncoated particles). Rapid and homogeneous mixing of core particle aerosol and coating precursor vapor facilitates synthesis of core-shell nanoparticles with uniform shell thickness and high coating efficiency (minimal uncoated core and free coating particles). PMID:23658471

  16. Design of Aerosol Coating Reactors: Precursor Injection

    PubMed Central

    Buesser, Beat; Pratsinis, Sotiris E.

    2013-01-01

    Particles are coated with thin shells to facilitate their processing and incorporation into liquid or solid matrixes without altering core particle properties (coloristic, magnetic, etc.). Here, computational fluid and particle dynamics are combined to investigate the geometry of an aerosol reactor for continuous coating of freshly-made titanium dioxide core nanoparticles with nanothin silica shells by injection of hexamethyldisiloxane (HMDSO) vapor downstream of TiO2 particle formation. The focus is on the influence of HMDSO vapor jet number and direction in terms of azimuth and inclination jet angles on process temperature and coated particle characteristics (shell thickness and fraction of uncoated particles). Rapid and homogeneous mixing of core particle aerosol and coating precursor vapor facilitates synthesis of core-shell nanoparticles with uniform shell thickness and high coating efficiency (minimal uncoated core and free coating particles). PMID:23658471

  17. MOCVD OF YSZ COATINGS USING ?-DIKETONATE PRECURSORS

    SciTech Connect

    Varanasi, Venu G; Besmann, Theodore M; Hyde, Robin L.; Payzant, E Andrew; Anderson, Timothy J

    2009-01-01

    Metallorganic chemical vapor deposition (MOCVD) was used to fabricate yttria-stabilized zirconia as a thermal barrier coating. The MOCVD precursors were Y(tmhd)3 and Zr(tmhd)4 (tmhd = 2, 2, 6, 6-tetramethyl-3, 5-heptanedianato) and delivered via aerosol assisted liquid delivery (AALD). The maximum tetragonal YSZ coating rate was 14.2 1.3 m h -1 (at 845oC) yielding a layered coating microstructure. The growth was first-order with temperature (T < 827oC) with an apparent activation energy (Ea) of 50.9 4.3 kJ mol -1. Coating efficiency was a maximum of approximately 10% at the highest growth rate.

  18. Filler/ Polycarbosilane Systems as CMC Matrix Precursors

    NASA Technical Reports Server (NTRS)

    Hurwitz, Frances I.

    1998-01-01

    Pyrolytic conversion of polymeric precursors to ceramics is accompanied by loss of volatiles and large volume changes. Infiltration of a low viscosity polymer into a fiber preform will fill small spaces within fiber tows by capillary forces, but create large matrix cracks within large, intertow areas. One approach to minimizing shrinkage and reducing the number of required infiltration cycles is to use particulate fillers. In this study, Starfire allylhydridopolycarbosilane (AHPCS) was blended with a silicon carbide powder, with and without dispersant, using shear mixing. The polymer and polymer/particle interactions were characterized using nuclear magnetic resonance, differential scanning calorimetry, thermogravimetric analysis and rheometry. Polymer/particulate slurries and suspensions were used to infiltrate a figidized preform of an eight ply five harness satin CG Nicalon fiber having a dual layer BN/SiC interface coating, and the resulting composites characterized by optical and scanning electron microscopy.

  19. Damage precursor measurements on UV optical coatings

    NASA Astrophysics Data System (ADS)

    Ettrich, K.; Blaschke, Holger; Welsch, Eberhard

    1995-07-01

    For application in UV thin film optics the thermal contribution to the laser-induced optical breakdown was investigated utilizing time-resolved photothermal probe beam deflection (MIRAGE) technique. The potentiality of this method for the determination of both the subdamage range and the onset of single-shot-damage of Al2O3/SiO2 and LaF3/MgF2 high-reflective coatings by using the thermal branch of the MIRAGE technique could be demonstrated. Examining the dielectric mirrors by 248 nm KrF laser irradiation, distinct damage precursor features were found. Thus, the physical origin of the UV-pulsed radiation breakdown in HR coatings can be elucidated.

  20. Silsesquioxanes as precursors to ceramic composites

    NASA Technical Reports Server (NTRS)

    Hurwitz, Frances I.; Hyatt, Lizbeth H.; Gorecki, Joy; Damore, Lisa

    1987-01-01

    Silsesquioxanes having the general structure RSiO sub 1.5, where R = methyl, propyl, or phenyl, melt flow at 70 to 100 C. Above 100 C, free -OH groups condense. At 225 C further crosslinking occurs, and the materials form thermosets. Pyrolysis, with accompanying loss of volatiles, takes place at nominally 525 C. At higher temperatures, the R group serves as an internal carbon soruce for carbo-thermal reduction to SiC accompanied by the evolution of CO. By blending silsesquioxanes with varying R groups, both the melt rheology and composition of the fired ceramic can be controlled. Fibers can be spun from the melt which are stable in argon in 1400 C. The silsesquioxanes also were used as matrix precursors for Nicalon and alpha-SiC platelet reinforced composites.

  1. The amyloid precursor protein: beyond amyloid

    PubMed Central

    Zheng, Hui; Koo, Edward H

    2006-01-01

    The amyloid precursor protein (APP) takes a central position in Alzheimer's disease (AD) pathogenesis: APP processing generates the β-amyloid (Aβ) peptides, which are deposited as the amyloid plaques in brains of AD individuals; Point mutations and duplications of APP are causal for a subset of early onset of familial Alzheimer's disease (FAD). Not surprisingly, the production and pathogenic effect of Aβ has been the central focus in AD field. Nevertheless, the biological properties of APP have also been the subject of intense investigation since its identification nearly 20 years ago as it demonstrates a number of interesting putative physiological roles. Several attractive models of APP function have been put forward recently based on in vitro biochemical studies. Genetic analyses of gain- and loss-of-function mutants in Drosophila and mouse have also revealed important insights into its biological activities in vivo. This article will review the current understanding of APP physiological functions. PMID:16930452

  2. N-nitrosodimethylamine precursors in malt.

    PubMed

    Wainwright, T; Slack, P T; Long, D E

    1982-01-01

    NDMA is formed in malt because NOx reacts with certain amines in germinated barley when it is kilned. Hordenine is the major precursor of NDMA, although gramine and sarcosine can possibly contribute minor amounts. The hordenine is formed in the developing seedling. The amount of hordenine present in unkilned malts, made using a variety of malting techniques, is always much more than sufficient to account for NDMA formation. Malting techniques which inhibit hordenine breakdown during kilning decrease NDMA formation. Nitrosated intermediates formed from hordenine on treating with NOx at relatively low temperatures (ca 40 degrees C), can be separated by HPLC. They give NDMA on heating with additional NOx. The conditions under which the intermediates are formed and under which they are converted to NDMA correspond to the observed pattern of NDMA formation during kilning. The effects of sulfuring at different times can be explained by the effects on formation and breakdown of the intermediates. PMID:6183201

  3. Raves: a review of the culture, the drugs and the prevention of harm

    PubMed Central

    Weir, E

    2000-01-01

    Raves are all-night dance parties attended by large numbers of youth, sometimes in excess of 20,000. The rave scene, which is international in scope, is distinguished by clandestine venues, hypnotic electronic music and the liberal use of drugs such as ecstasy (3,4-methylenedioxymethamphetamine), GHB (gamma-hydroxybutyrate) and ketamine. Several rave-related deaths in Canada in 1999 alerted health authorities, parents and police to the health risks of rave attendance. Family physicians, emergency physicians and pediatricians should have some understanding of raves, the drugs and the health risks so they can effectively counsel and treat patients. The rave culture in Canada and the drugs commonly used at raves are reviewed, and strategies and initiatives for harm reduction are discussed. PMID:10906922

  4. From club drug to orphan drug: sodium oxybate (Xyrem) for the treatment of cataplexy.

    PubMed

    Fuller, David E; Hornfeldt, Carl S

    2003-09-01

    Narcolepsy, a rare disease with a prevalence of 0.05% in the general population, affects an estimated 140,000 patients in the United States. Patients have been able to lead fuller personal and professional lives since the Food and Drug Administration approved sodium oxybate (Xyrem) in 2002 for treatment of cataplexy in patients with narcolepsy. Previously, gamma-hydroxybutyrate (GHB), the active ingredient of sodium oxybate, had been a substance of abuse, most notoriously as a date-rape drug. Public Law 106-172, the date-rape prohibition act enacted in 2000, was modified to allow the drug to be legally administered for medical purposes. Because of the apprehension regarding the risk of possible drug diversion after the approval of sodium oxybate and concerns about safety, the Xyrem Risk Management Program was created. This program has been successful in satisfying the needs of patients and physicians while ensuring responsible distribution of the drug. PMID:14524654

  5. Polymer precursors for ceramic matrix composites

    NASA Technical Reports Server (NTRS)

    Litt, M. H.; Kumar, K.

    1986-01-01

    The synthesis and characterization of a polycyclohexasilane is reported. Because of its cyclic structure, it is anticipated that this polymer might serve as a precursor to SIC having a high char yield with little rearrangement to form small, volatile cyclic silanes, and, as such, would be of interest as a precursor to SiC composite matrices and fibers, or as a binder in ceramic processing. Several approaches to the synthesis of a bifunctional cyclic monomer were attempted; the most successful of these was metal coupling of PhMeSiCl2 and Me2SiCl2. The procedure gives six-membered ring compounds with all degrees of phenyl substitution, from none to hexaphenyl. The compounds with from 0-2 groups were isolated and characterized. The fraction with degree of phenyl substitution equal to 2, a mixture of cis and trans 1,2-; 1,3-; and 1,4 isomers, was isolated in 32 percent yield. Pure 1,4 diphenyldecamethylcyclohexasilane was isolated from the mixed diphenyl compounds and characterized. Diphenyldecamethylcyclohexasilanes were dephenylated to dichlorodecamethylcyclohexasilanes by treating with H2SO4.NH4Cl in benzene. The latter were purified and polymerized by reacting with sodium in toluene. The polymers were characterized by HPGPC, elemental analysis, proton NMR, and IR. Thermogravimetric analyses were carried out on the polymers. As the yield of residual SiC was low, polymers were heat treated to increase the residual char yield. As high as 51.52 percent residual char yield was obtained in one case.

  6. Thermal Stability of Jet Fuels: Kinetics of Forming Deposit Precursors

    NASA Technical Reports Server (NTRS)

    Naegeli, David W.

    1997-01-01

    The focus of this study was on the autoxidation kinetics of deposit precursor formation in jet fuels. The objectives were: (1) to demonstrate that laser-induced fluorescence is a viable kinetic tool for measuring rates of deposit precursor formation in jet fuels; (2) to determine global rate expressions for the formation of thermal deposit precursors in jet fuels; and (3) to better understand the chemical mechanism of thermal stability. The fuels were isothermally stressed in small glass ampules in the 120 to 180 C range. Concentrations of deposit precursor, hydroperoxide and oxygen consumption were measured over time in the thermally stressed fuels. Deposit precursors were measured using laser-induced fluorescence (LIF), hydroperoxides using a spectrophotometric technique, and oxygen consumption by the pressure loss in the ampule. The expressions, I.P. = 1.278 x 10(exp -11)exp(28,517.9/RT) and R(sub dp) = 2.382 x 10(exp 17)exp(-34,369.2/RT) for the induction period, I.P. and rate of deposit precursor formation R(sub dp), were determined for Jet A fuel. The results of the study support a new theory of deposit formation in jet fuels, which suggest that acid catalyzed ionic reactions compete with free radical reactions to form deposit precursors. The results indicate that deposit precursors form only when aromatics are present in the fuel. Traces of sulfur reduce the rate of autoxidation but increase the yield of deposit precursor. Free radical chemistry is responsible for hydroperoxide formation and the oxidation of sulfur compounds to sulfonic acids. Phenols are then formed by the acid catalyzed decomposition of benzylic hydroperoxides, and deposit precursors are produced by the reaction of phenols with aldehydes, which forms a polymer similar to Bakelite. Deposit precursors appear to have a phenolic resin-like structure because the LIF spectra of the deposit precursors were similar to that of phenolic resin dissolved in TAM.

  7. Primary structure and tissue distribution of the orphanin FQ precursor.

    PubMed Central

    Nothacker, H P; Reinscheid, R K; Mansour, A; Henningsen, R A; Ardati, A; Monsma, F J; Watson, S J; Civelli, O

    1996-01-01

    The heptadecapeptide orphanin FQ (OFQ) is a recently discovered neuropeptide that exhibits structural features reminiscent of the opioid peptides and that is an endogenous ligand to a G protein-coupled receptor sequentially related to the opioid receptors. We have cloned both the human and rat cDNAs encoding the OFQ precursor proteins, to investigate whether the sequence relationships existing between the opioid and OFQ systems are also found at the polypeptide precursor level, in particular whether the OFQ precursor would encode several bioactive peptides as do the opioid precursors, and to study the regional distribution of OFQ sites of synthesis. The entire precursor protein displays structural homology to the opioid peptide precursors, especially preprodynorphin and preproenkephalin. The predicted amino acid sequence of the OFQ precursor contains a putative signal peptide and one copy of the OFQ sequence flanked by pairs of basic amino acid residues. Carboxyl-terminal to the OFQ sequence, the human and rat precursors contain a stretch of 28 amino acids that is 100% conserved and thus may encode novel bioactive peptides. Two peptides derived from this stretch were synthesized but were found to be unable to activate the OFQ receptor, suggesting that if they are produced in vivo, these peptides would likely recognize receptors different from the OFQ receptor. To begin analyzing the sites of OFQ mRNA synthesis, Northern analysis of human and rat tissues were carried out and showed that the OFQ precursor mRNA is mainly expressed in the brain. In situ hybridization of rat brain slices demonstrated a regional distribution pattern of the OFQ precursor mRNA, which is distinct from that of the opioid peptide precursors. These data confirm that the OFQ system differs from the opioid system at the molecular level, although the OFQ and opioid precursors may have arisen from a common ancestral gene. Images Fig. 4 Fig. 5 PMID:8710930

  8. Distinction of gaseous soot precursor molecules and soot precursor particles through photoionization mass spectrometry.

    PubMed

    Happold, Joachim; Grotheer, Horst-Henning; Aigner, Manfred

    2007-01-01

    Samples were drawn from sooting premixed low-pressure ethylene oxygen flames and investigated through photoionization mass spectrometry using either KrF or ArF lasers as the radiation source. With the former, mass spectra were obtained as described in the literature and characterized through a series of signal groups, one for each C-number and extending to about m/z 1000, assigned as a PAH series. When the ArF laser was used the same series was observed with a somewhat higher sensitivity. In addition, a new series was observed overlaid on the PAH series and starting at about m/z 680. The new series exhibited abundant ions and it completely dominated the spectrum beyond m/z 1000. This series was identified as being the spectrum of soot precursor particles. Through measurement of the ionization order it was concluded that at least two photons are needed for ionization of PAHs whereas the particles need only one photon. Consequently, they can be measured with high sensitivity when an ArF laser is used as the radiation source. Furthermore, the discrimination of soot precursor molecules and soot precursor particles becomes possible through photoionization and this enables an improved understanding of the mass spectra. This should allow a particle growth mechanism to be deduced in the near future. PMID:17342787

  9. Frog Swarms: Earthquake Precursors or False Alarms?

    PubMed Central

    Grant, Rachel A.; Conlan, Hilary

    2013-01-01

    Simple Summary Media reports linking unusual animal behaviour with earthquakes can potentially create false alarms and unnecessary anxiety among people that live in earthquake risk zones. Recently large frog swarms in China and elsewhere have been reported as earthquake precursors in the media. By examining international media reports of frog swarms since 1850 in comparison to earthquake data, it was concluded that frog swarms are naturally occurring dispersal behaviour of juveniles and are not associated with earthquakes. However, the media in seismic risk areas may be more likely to report frog swarms, and more likely to disseminate reports on frog swarms after earthquakes have occurred, leading to an apparent link between frog swarms and earthquakes. Abstract In short-term earthquake risk forecasting, the avoidance of false alarms is of utmost importance to preclude the possibility of unnecessary panic among populations in seismic hazard areas. Unusual animal behaviour prior to earthquakes has been reported for millennia but has rarely been scientifically documented. Recently large migrations or unusual behaviour of amphibians have been linked to large earthquakes, and media reports of large frog and toad migrations in areas of high seismic risk such as Greece and China have led to fears of a subsequent large earthquake. However, at certain times of year large migrations are part of the normal behavioural repertoire of amphibians. News reports of “frog swarms” from 1850 to the present day were examined for evidence that this behaviour is a precursor to large earthquakes. It was found that only two of 28 reported frog swarms preceded large earthquakes (Sichuan province, China in 2008 and 2010). All of the reported mass migrations of amphibians occurred in late spring, summer and autumn and appeared to relate to small juvenile anurans (frogs and toads). It was concluded that most reported “frog swarms” are actually normal behaviour, probably caused by juvenile animals migrating away from their breeding pond, after a fruitful reproductive season. As amphibian populations undergo large fluctuations in numbers from year to year, this phenomenon will not occur on a yearly basis but will depend on successful reproduction, which is related to numerous climatic and geophysical factors. Hence, most large swarms of amphibians, particularly those involving very small frogs and occurring in late spring or summer, are not unusual and should not be considered earthquake precursors. In addition, it is likely that reports of several mass migration of small toads prior to the Great Sichuan Earthquake in 2008 were not linked to the subsequent M = 7.9 event (some occurred at a great distance from the epicentre), and were probably co-incidence. Statistical analysis of the data indicated frog swarms are unlikely to be connected with earthquakes. Reports of unusual behaviour giving rise to earthquake fears should be interpreted with caution, and consultation with experts in the field of earthquake biology is advised. PMID:26479746

  10. Frog Swarms: Earthquake Precursors or False Alarms?

    PubMed

    Grant, Rachel A; Conlan, Hilary

    2013-01-01

    In short-term earthquake risk forecasting, the avoidance of false alarms is of utmost importance to preclude the possibility of unnecessary panic among populations in seismic hazard areas. Unusual animal behaviour prior to earthquakes has been reported for millennia but has rarely been scientifically documented. Recently large migrations or unusual behaviour of amphibians have been linked to large earthquakes, and media reports of large frog and toad migrations in areas of high seismic risk such as Greece and China have led to fears of a subsequent large earthquake. However, at certain times of year large migrations are part of the normal behavioural repertoire of amphibians. News reports of "frog swarms" from 1850 to the present day were examined for evidence that this behaviour is a precursor to large earthquakes. It was found that only two of 28 reported frog swarms preceded large earthquakes (Sichuan province, China in 2008 and 2010). All of the reported mass migrations of amphibians occurred in late spring, summer and autumn and appeared to relate to small juvenile anurans (frogs and toads). It was concluded that most reported "frog swarms" are actually normal behaviour, probably caused by juvenile animals migrating away from their breeding pond, after a fruitful reproductive season. As amphibian populations undergo large fluctuations in numbers from year to year, this phenomenon will not occur on a yearly basis but will depend on successful reproduction, which is related to numerous climatic and geophysical factors. Hence, most large swarms of amphibians, particularly those involving very small frogs and occurring in late spring or summer, are not unusual and should not be considered earthquake precursors. In addition, it is likely that reports of several mass migration of small toads prior to the Great Sichuan Earthquake in 2008 were not linked to the subsequent M = 7.9 event (some occurred at a great distance from the epicentre), and were probably co-incidence. Statistical analysis of the data indicated frog swarms are unlikely to be connected with earthquakes. Reports of unusual behaviour giving rise to earthquake fears should be interpreted with caution, and consultation with experts in the field of earthquake biology is advised. PMID:26479746

  11. An Evaluation of Strengthening Precursors to Increase Preschooler Compliance

    ERIC Educational Resources Information Center

    Kraus, Aaron J.; Hanley, Gregory P.; Cesana, Lori L.; Eisenberg, Danielle; Jarvie, Adam C.

    2012-01-01

    We evaluated the strategy of increasing precursors to compliance on the compliance of 2 preschool boys. Modeling and differential reinforcement were used to increase specific responses to his name being called prior to the opportunity to comply with an instruction. The precursors were stopping the ongoing activity and orienting to, making eye…

  12. Topographical and Functional Properties of Precursors to Severe Problem Behavior

    ERIC Educational Resources Information Center

    Fahmie, Tara A.; Iwata, Brian A.

    2011-01-01

    A literature search identified 17 articles reporting data on 34 subjects who engaged in precursors to severe problem behavior, which we examined to identify topographical and functional characteristics. Unintelligible vocalization was the most common precursor to aggression (27%) and property destruction (29%), whereas self- or nondirected…

  13. Diversity of Neural Precursors in the Adult Mammalian Brain.

    PubMed

    Bonaguidi, Michael A; Stadel, Ryan P; Berg, Daniel A; Sun, Jiaqi; Ming, Guo-Li; Song, Hongjun

    2016-01-01

    Aided by advances in technology, recent studies of neural precursor identity and regulation have revealed various cell types as contributors to ongoing cell genesis in the adult mammalian brain. Here, we use stem-cell biology as a framework to highlight the diversity of adult neural precursor populations and emphasize their hierarchy, organization, and plasticity under physiological and pathological conditions. PMID:26988967

  14. A Procedure for Identifying Precursors to Problem Behavior

    ERIC Educational Resources Information Center

    Herscovitch, Brandon; Roscoe, Eileen M.; Libby, Myrna E.; Bourret, Jason C.; Ahearn, William H.

    2009-01-01

    We describe a procedure for differentiating among potential precursor responses for use in a functional analysis. Conditional probability analysis of descriptive assessment data identified three potential precursors. Results from the indirect assessment corresponded with those obtained from the descriptive assessment. The top-ranked response

  15. Precursors to Aggression Are Evident by 6 Months of Age

    ERIC Educational Resources Information Center

    Hay, Dale F.; Waters, Cerith S.; Perra, Oliver; Swift, Naomi; Kairis, Victoria; Phillips, Rebecca; Jones, Roland; Goodyer, Ian; Harold, Gordon; Thapar, Anita; van Goozen, Stephanie

    2014-01-01

    We tested the hypothesis that developmental precursors to aggression are apparent in infancy. Up to three informants rated 301 firstborn infants for early signs of anger, hitting and biting; 279 (93%) were assessed again as toddlers. Informants' ratings were validated by direct observation at both ages. The precursor behaviours were…

  16. Precursor Flow Separation Detection Using Plasma Actuators

    NASA Astrophysics Data System (ADS)

    Bowles, Patrick; Corke, Thomas

    2008-11-01

    A method for detecting incipient flow separation using plasma actuators is presented. The detection scheme relies upon the receptivity of the flow to unsteady disturbances that are introduced by the flow actuator. The receptivity to the unsteady disturbances is heightened as the flow approaches the separation limit, and subsequently can be detected downstream. This is demonstrated on a dynamically pitching airfoil that progresses through a dynamic stall cycle. A plasma actuator is located at the leading edge and pulsed at a frequency that is optimal to re-attach the flow. A pressure sensor monitors the unsteady pressure disturbances on the suction-side of the airfoil. Short-time Fourier analysis and Wavelet analysis capture the time-frequency behavior of the pressure sensor time series. Simultaneous flow visualization using a high-speed camera aid in elucidating the fluid response to the actuator input. The method not only provides a precursor for flow separation, but also an indicator when conditions exist where active re-attachment control is no longer needed. A closed-loop, feedback control scheme based on this is demonstrated.

  17. Assimilation of NAD(+) precursors in Candida glabrata.

    PubMed

    Ma, Biao; Pan, Shih-Jung; Zupancic, Margaret L; Cormack, Brendan P

    2007-10-01

    The yeast pathogen Candida glabrata is a nicotinamide adenine dinucleotide (NAD(+)) auxotroph and its growth depends on the environmental supply of vitamin precursors of NAD(+). C. glabrata salvage pathways defined in this article allow NAD(+) to be synthesized from three compounds - nicotinic acid (NA), nicotinamide (NAM) and nicotinamide riboside (NR). NA is salvaged through a functional Preiss-Handler pathway. NAM is first converted to NA by nicotinamidase and then salvaged by the Preiss-Handler pathway. Salvage of NR in C. glabrata occurs via two routes. The first, in which NR is phosphorylated by the NR kinase Nrk1, is independent of the Preiss-Handler pathway. The second is a novel pathway in which NR is degraded by the nucleosidases Pnp1 and Urh1, with a minor role for Meu1, and ultimately converted to NAD(+) via the nicotinamidase Pnc1 and the Preiss-Handler pathway. Using C. glabrata mutants whose growth depends exclusively on the external NA or NR supply, we also show that C. glabrata utilizes NR and to a lesser extent NA as NAD(+) sources during disseminated infection. PMID:17725566

  18. Characterization of marginal zone B cell precursors

    PubMed Central

    Srivastava, Bhaskar; Quinn, William J.; Hazard, Kristin; Erikson, Jan; Allman, David

    2005-01-01

    Selection of recently formed B cells into the follicular or marginal zone (MZ) compartments is proposed to occur by way of proliferative intermediates expressing high levels of CD21/35 and CD23. However, we show that CD21/35high CD23+ splenocytes are not enriched for proliferative cells, and do not contribute substantially to the generation of follicular B cells. Instead, ontogenic relationships, steady-state labeling kinetics, and adoptive transfer experiments suggest that CD21/35high CD23+ splenocytes serve primarily as precursors for MZ B cells, although their developmental potential seems to be broader and is influenced by environmental cues that are associated with lymphopenia. Furthermore, CD21/35high CD23+ splenocytes share several key functional characteristics with MZ B cells, including their capacity to trap T-independent antigen and a heightened proliferative response to LPS. These observations challenge previous models of peripheral B cell maturation, and suggest that MZ B cells develop by way of CD21/35high CD23+ intermediates. PMID:16260487

  19. A Fission-Powered Interstellar Precursor Mission

    SciTech Connect

    Lenard, R.X.; Lipinski, R.J.; West, J.L.; Wright, S.A.

    1998-10-28

    An 'interstellar precursor mission' lays the groundwork for eventual interstellar exploration by studying the interstellar medium and by stretching technologies that have potential application for eventual interstellar exploration. The numerous scientific goals for such a mission include generating a 3-D stellar map of our galaxy, studying Kuiper-belt and Oort cloud objects, and observing distant objects using the sun's gravitational lens as the primary of an enormous telescope. System equations are developed for a space tug which propels a 2500-kg scientific payload to 550 astronomical units in about 20 years. The tug to transport this payload uses electric propulsion with an Isp of 15,000 seconds and a fission reactor with a closed Brayton cycle to genemte the electricity. The optimal configuration may be to thrust for only about 6 years and then coast for the remaining 14 pars. This spacecraft does not require any physics breakthroughs or major advances in technology. The fission power syslem can be engineered and built by drawing upon known technologies developed for relatgd systems over the past 40 years. The tug system would eventually reach 1000 a.u in 33 years, and would have adequate power to relay large amounts of data throughout its journey.

  20. Mars MetNet Precursor Mission Status

    NASA Astrophysics Data System (ADS)

    Harri, Ari-Matti; Aleksashkin, Sergey; Guerrero, Héctor; Schmidt, Walter; Genzer, Maria; Vazquez, Luis; Haukka, Harri

    2013-04-01

    A new kind of planetary exploration mission for Mars is being developed in collaboration between the Finnish Meteorological Institute (FMI), Lavochkin Association (LA), Space Research Institute (IKI) and Institutio Nacional de Tecnica Aerospacial (INTA). The Mars MetNet mission is based on a new semi-hard landing vehicle called MetNet Lander (MNL), using an inflatable entry and descent system instead of rigid heat shields and parachutes as earlier semi-hard landing devices have used. This way the ratio of the payload mass to the overall mass is optimized. The landing impact will burrow the payload container into the Martian soil providing a more favorable thermal environment for the electronics and a suitable orientation of the telescopic boom with external sensors and the radio link antenna. It is planned to deploy several tens of MNLs on the Martian surface operating at least partly at the same time to allow meteorological network science. For the precursor mission (MMPM) intended to verify the landing concept and key technology during a real Mars mission all qualification activities are completed and the payload and system flight model components are being manufactured. The descent processes dynamic properties are monitored by a special 3-axis accelerometer combined with a 3-axis gyrometer. The data will be sent via auxiliary beacon antenna throughout the descent phase starting shortly after separation from the spacecraft. Details of the current MMPM system and payload configuration and their performance parameters will be shown.

  1. Robotic Precursor Missions for Mars Habitats

    NASA Astrophysics Data System (ADS)

    Huntsberger, Terry; Pirjanian, Paolo; Schenker, Paul S.; Trebi-Ollennu, Ashitey; Das, Hari; Joshi, Sajay

    2000-07-01

    Infrastructure support for robotic colonies, manned Mars habitat, and/or robotic exploration of planetary surfaces will need to rely on the field deployment of multiple robust robots. This support includes such tasks as the deployment and servicing of power systems and ISRU generators, construction of beaconed roadways, and the site preparation and deployment of manned habitat modules. The current level of autonomy of planetary rovers such as Sojourner will need to be greatly enhanced for these types of operations. In addition, single robotic platforms will not be capable of complicated construction scenarios. Precursor robotic missions to Mars that involve teams of multiple cooperating robots to accomplish some of these tasks is a cost effective solution to the possible long timeline necessary for the deployment of a manned habitat. Ongoing work at JPL under the Mars Outpost Program in the area of robot colonies is investigating many of the technology developments necessary for such an ambitious undertaking. Some of the issues that are being addressed include behavior-based control systems for multiple cooperating robots (CAMPOUT), development of autonomous robotic systems for the rescue/repair of trapped or disabled robots, and the design and development of robotic platforms for construction tasks such as material transport and surface clearing.

  2. Bacterial Cellular Materials as Precursors of Chloroform

    NASA Astrophysics Data System (ADS)

    Wang, J.; Ng, T.; Zhang, Q.; Chow, A. T.; Wong, P.

    2011-12-01

    The environmental sources of chloroform and other halocarbons have been intensively investigated because their effects of stratospheric ozone destruction and environmental toxicity. It has been demonstrated that microorganisms could facilitate the biotic generation of chloroform from natural organic matters in soil, but whether the cellular materials itself also serves as an important precursor due to photo-disinfection is poorly known. Herein, seven common pure bacterial cultures (Acinetobacter junii, Aeromonas hydrophila, Bacillus cereus, Bacillus substilis, Escherichia coli, Shigella sonnei, Staphylococcus sciuri) were chlorinated to evaluate the yields of chloroform, dibromochloromethane, dichlorobromomethane, and bromoform. The effects of bromide on these chemical productions and speciations were also investigated. Results showed that, on average, 5.64-36.42 μg-chloroform /mg-C were generated during the bacterial chlorination, in similar order of magnitude to that generated by humic acid (previously reported as 78 μg-chloroform/mg-C). However, unlike humic acid in water chlorination, chloroform concentration did not simply increase with the total organic carbon in water mixture. In the presence of bromide, the yield of brominated species responded linearly to the bromide concentration. This study provides useful information to understand the contributions of chloroform from photodisinfection processes in coastal environments.

  3. Amyloid precursor protein in aged nonhuman primates.

    PubMed Central

    Martin, L J; Sisodia, S S; Koo, E H; Cork, L C; Dellovade, T L; Weidemann, A; Beyreuther, K; Masters, C; Price, D L

    1991-01-01

    In individuals with Alzheimer disease and in aged nonhuman primates, deposits of amyloid occur in senile plaques in brain parenchyma and in the walls of some meningeal and cortical vessels. Amyloid is primarily composed of beta/A4, a 4-kDa peptide derived from the transmembrane form of an amyloid precursor protein (APP). We examined the distribution of beta/A4 and APP (outside the beta/A4 domain) in cerebral cortices of monkeys ranging in age from 4 to 41 years. In all animals, APP immunoreactivity was present in cell bodies, proximal dendrites, and axons of cortical neurons. In aged animals, all of which showed senile plaques, large APP-positive axons were conspicuous, and APP immunoreactivity was present in neurites around beta/A4-immunoreactive plaques. In some plaques, APP-immunoreactive elements were located in proximity to deposits of beta/A4. The presence of APP immunoreactivity in neuronal perikarya, dendrites, axons, and in neurites within beta/A4-containing plaques supports the hypothesis that neurons can serve as one source of amyloid deposited in brain parenchyma. Images PMID:1899927

  4. Precursors To Interstellar Shocks of Solar Origin

    NASA Astrophysics Data System (ADS)

    Gurnett, D. A.; Kurth, W. S.; Stone, E. C.; Cummings, A. C.; Krimigis, S. M.; Decker, R. B.; Ness, N. F.; Burlaga, L. F.

    2015-08-01

    On or about 2012 August 25, the Voyager 1 spacecraft crossed the heliopause into the nearby interstellar plasma. In the nearly three years that the spacecraft has been in interstellar space, three notable particle and field disturbances have been observed, each apparently associated with a shock wave propagating outward from the Sun. Here, we present a detailed analysis of the third and most impressive of these disturbances, with brief comparisons to the two previous events, both of which have been previously reported. The shock responsible for the third event was first detected on 2014 February 17 by the onset of narrowband radio emissions from the approaching shock, followed on 2014 May 13 by the abrupt appearance of intense electron plasma oscillations generated by electrons streaming outward ahead of the shock. Finally, the shock arrived on 2014 August 25, as indicated by a jump in the magnetic field strength and the plasma density. Various disturbances in the intensity and anisotropy of galactic cosmic rays were also observed ahead of the shock, some of which are believed to be caused by the reflection and acceleration of cosmic rays by the magnetic field jump at the shock, and/or by interactions with upstream plasma waves. Comparisons to the two previous weaker events show somewhat similar precursor effects, although differing in certain details. Many of these effects are very similar to those observed in the region called the “foreshock” that occurs upstream of planetary bow shocks, only on a vastly larger spatial scale.

  5. A fission-powered interstellar precursor mission

    SciTech Connect

    Lipinski, Ronald J.; Lenard, Roger X.; Wright, Steven A. West, John L.

    1999-01-01

    An {open_quotes}interstellar precursor mission{close_quotes} lays the groundwork for eventual interstellar exploration by studying the interstellar medium and by stretching technologies that have potential application for eventual interstellar exploration. The numerous scientific goals for such a mission include generating a 3-D stellar map of our galaxy, studying Kuiper-belt and Oort cloud objects, and observing distant objects using the sun{close_quote}s gravitational lens as the primary of an enormous telescope. System equations are developed for a space tug which propels a 2500-kg scientific payload to 550 astronomical units in about 20 years. The tug to transport this payload uses electric propulsion with an lsp of 15,000 seconds and a fission reactor with a closed Brayton cycle to generate the electricity. The optimal configuration may be to thrust for only about 6 years and then coast for the remaining 14 years. This spacecraft does not require any physics breakthroughs or major advances in technology. The fission power system can be engineered and built by drawing upon known technologies developed for related systems over the past 40 years. The tug system would eventually reach 1000 a.u in 33 years, and would have adequate power to relay large amounts of data throughout its journey. {copyright} {ital 1999 American Institute of Physics.}

  6. Cystic precursors to invasive pancreatic cancer

    PubMed Central

    Matthaei, Hanno; Schulick, Richard D.; Hruban, Ralph H.; Maitra, Anirban

    2011-01-01

    Improvements in the sensitivity and quality of cross-sectional imaging have led to increasing numbers of patients being diagnosed with cystic lesions of the pancreas. In parallel, clinical, radiological, pathological and molecular studies have improved the systems for classifying these cysts. Patients with asymptomatic serous cystic neoplasms can be managed conservatively with regular monitoring; however, the clinical management of patients with intraductal papillary mucinous neoplasms and mucinous cystic neoplasms is far more challenging, as it is difficult to determine whether these lesions will progress to malignancy. Fortunately, prospective studies have helped to establish that proposed clinical and radiological criteria (the Sendai guidelines) can be used to guide the care of patients with cystic lesions of the pancreas. Despite this progress in imaging and clinical guidelines, sensitive and specific tests have not yet been developed that can reliably predict the histology and biological properties of a cystic lesion. Such biomarkers are urgently needed, as noninvasive precursors of pancreatic cancer are curable, while the vast majority of invasive pancreatic adenocarcinomas are not. PMID:21383670

  7. Forecasting a CME by Spectroscopic Precursor?

    NASA Astrophysics Data System (ADS)

    Baker, D.; van Driel-Gesztelyi, L.; Green, L. M.

    2012-02-01

    Multi-temperature plasma flows resulting from the interaction between a mature active region (AR) inside an equatorial coronal hole (CH) are investigated. Outflow velocities observed by Hinode EIS ranged from a few to 13 km s-1 for three days at the AR’s eastern and western edges. However, on the fourth day, velocities intensified up to 20 km s-1 at the AR’s western footpoint about six hours prior to a CME. 3D MHD numerical simulations of the observed magnetic configuration of the AR-CH complex showed that the expansion of the mature AR’s loops drives persistent outflows along the neighboring CH field (Murray et al. in Solar Phys. 261, 253, 2010). Based on these simulations, intensification of outflows observed pre-eruption on the AR’s western side where same-polarity AR and CH field interface, is interpreted to be the result of the expansion of a sigmoidal AR, in particular, a flux rope containing a filament that provides stronger compression of the neighboring CH field on this side of the AR. Intensification of outflows in the AR is proposed as a new type of CME precursor.

  8. The Amyloid Precursor Protein Controls PIKfyve Function

    PubMed Central

    Balklava, Zita; Niehage, Christian; Currinn, Heather; Mellor, Laura; Guscott, Benjamin; Poulin, Gino; Hoflack, Bernard; Wassmer, Thomas

    2015-01-01

    While the Amyloid Precursor Protein (APP) plays a central role in Alzheimer’s disease, its cellular function still remains largely unclear. It was our goal to establish APP function which will provide insights into APP's implication in Alzheimer's disease. Using our recently developed proteo-liposome assay we established the interactome of APP's intracellular domain (known as AICD), thereby identifying novel APP interactors that provide mechanistic insights into APP function. By combining biochemical, cell biological and genetic approaches we validated the functional significance of one of these novel interactors. Here we show that APP binds the PIKfyve complex, an essential kinase for the synthesis of the endosomal phosphoinositide phosphatidylinositol-3,5-bisphosphate. This signalling lipid plays a crucial role in endosomal homeostasis and receptor sorting. Loss of PIKfyve function by mutation causes profound neurodegeneration in mammals. Using C. elegans genetics we demonstrate that APP functionally cooperates with PIKfyve in vivo. This regulation is required for maintaining endosomal and neuronal function. Our findings establish an unexpected role for APP in the regulation of endosomal phosphoinositide metabolism with dramatic consequences for endosomal biology and important implications for our understanding of Alzheimer's disease. PMID:26125944

  9. Neural Precursor Lineages Specify Distinct Neocortical Pyramidal Neuron Types

    PubMed Central

    Tyler, William A.; Medalla, Maria; Guillamon-Vivancos, Teresa

    2015-01-01

    Several neural precursor populations contemporaneously generate neurons in the developing neocortex. Specifically, radial glial stem cells of the dorsal telencephalon divide asymmetrically to produce excitatory neurons, but also indirectly to produce neurons via three types of intermediate progenitor cells. Why so many precursor types are needed to produce neurons has not been established; whether different intermediate progenitor cells merely expand the output of radial glia or instead generate distinct types of neurons is unknown. Here we use a novel genetic fate mapping technique to simultaneously track multiple precursor streams in the developing mouse brain and show that layer 2 and 3 pyramidal neurons exhibit distinctive electrophysiological and structural properties depending upon their precursor cell type of origin. These data indicate that individual precursor subclasses synchronously produce functionally different neurons, even within the same lamina, and identify a primary mechanism leading to cortical neuronal diversity. PMID:25878286

  10. Precursor of kunitz trypsin inhibitor in soybean seeds

    SciTech Connect

    McGrain, A.; Chen, J.; Tan-Wilson, A. )

    1990-05-01

    Kunitz soybean trypsin inhibitor (KSTI) appears to be synthesized in precursor form which is converted by proteolytic digestion to the mature form of KSTI. Two forms of anti-cross-reacting material are evident when Western blots of extracts of developing seeds are analyzed. The precursor form increases to maximum levels as seed lengths increase to 11 mm. As the seed matures to 13 mm and turns yellow, precursor levels decrease while mature KSTI levels increase. The conversion of precursor to mature form could be demonstrated in vitro in seed extracts. The conversion could also be demonstrated in excised seeds pulse-labeled with ({sup 14}C)-leucine as loss of radioactivity from the precursor and appearance in the mature KSTI form.

  11. PRECOMBUSTION REMOVAL OF HAZARDOUS AIR POLLUTANT PRECURSORS

    SciTech Connect

    Unknown

    2000-10-09

    In response to growing environmental concerns reflected in the 1990 Clean Air Act Amendment (CAAA), the United States Department of Energy (DOE) sponsored several research and development projects in late 1995 as part of an initiative entitled Advanced Environmental Control Technologies for Coal-Based Power Systems. The program provided cost-shared support for research and development projects that could accelerate the commercialization of affordable, high-efficiency, low-emission, coal-fueled electric generating technologies. Clean coal technologies developed under this program would serve as prototypes for later generations of technologies to be implemented in the industrial sector. In order to identify technologies with the greatest potential for commercial implementation, projects funded under Phase I of this program were subject to competitive review by DOE before being considered for continuation funding under Phase II. One of the primary topical areas identified under the DOE initiative relates to the development of improved technologies for reducing the emissions of air toxics. Previous studies have suggested that many of the potentially hazardous air pollutant precursors (HAPPs) occur as trace elements in the mineral matter of run-of-mine coals. As a result, these elements have the potential to be removed prior to combustion at the mine site by physical coal cleaning processes (i.e., coal preparation). Unfortunately, existing coal preparation plants are generally limited in their ability to remove HAPPs due to incomplete liberation of the mineral matter and high organic associations of some trace elements. In addition, existing physical coal cleaning plants are not specifically designed or optimized to ensure that high trace element rejections may be achieved.

  12. Precursor Science for the Terrestrial Planet Finder

    NASA Technical Reports Server (NTRS)

    Lawson, P. R. (Editor); Unwin, S. C. (Editor); Beichman, C. A. (Editor)

    2004-01-01

    This document outlines a path for the development of the field of extrasolar planet research, with a particular emphasis on the goals of the Terrestrial Planet Finder (TPF). Over the past decade, a new field of research has developed, the study of extrasolar planetary systems, driven by the discovery of massive planets around nearby stars. The planet count now stands at over 130. Are there Earth-like planets around nearby stars? Might any of those planets be conducive to the formation and maintenance of life? These arc the questions that TPF seeks to answer. TPF will be implemented as a suite of two space observatories, a 6-m class optical coronagraph, to be launched around 20 14, and a formation flying mid-infrared interferometer, to be launched sometime prior to 2020. These facilities will survey up to 165 or more nearby stars and detect planets like Earth should they be present in the 'habitable zone' around each star. With observations over a broad wavelength range, TPF will provide a robust determination of the atmospheric composition of planets to assess habitability and the presence of life. At this early stage of TPF's development, precursor observational and theoretical programs are essential to help define the mission, to aid our understanding of the planets that TPF could discover, and to characterize the stars that TPF will eventually study. This document is necessarily broad in scope because the significance of individual discoveries is greatly enhanced when viewed in thc context of the field as a whole. This document has the ambitious goal of taking us from our limited knowledge today, in 2004, to the era of TPF observations in the middle of the next decade. We must use the intervening years wisely. This document will be reviewed annually and updated as needed. The most recent edition is available online at http://tpf.jpl.nasa.gov/ or by email request to lawson@hucy.jpl.nasa.gov

  13. PHOTOSPHERIC RADIUS EXPANSION IN SUPERBURST PRECURSORS FROM NEUTRON STARS

    SciTech Connect

    Keek, L.

    2012-09-10

    Thermonuclear runaway burning of carbon is in rare cases observed from accreting neutron stars as day-long X-ray flares called superbursts. In the few cases where the onset is observed, superbursts exhibit a short precursor burst at the start. In each instance, however, the data are of insufficient quality for spectral analysis of the precursor. Using data from the propane anti-coincidence detector of the Proportional Counter Array instrument on the Rossi X-ray Timing Explorer, we perform the first detailed time-resolved spectroscopy of precursors. For a superburst from 4U 1820-30 we demonstrate the presence of photospheric radius expansion. We find the precursor to be 1.4-2 times more energetic than other short bursts from this source, indicating that the burning of accreted helium is insufficient to explain the full precursor. Shock heating would be able to account for the shortfall in energy. We argue that this precursor is a strong indication that the superburst starts as a detonation, and that a shock induces the precursor. Furthermore, we employ our technique to study the superexpansion phase of the same superburst in greater detail.

  14. Clustering chlorine reactivity of haloacetic acid precursors in inland lakes.

    PubMed

    Zeng, Teng; Arnold, William A

    2014-01-01

    Dissolved organic matter (DOM) represents the major pool of organic precursors for harmful disinfection byproducts, such as haloacetic acids (HAAs), formed during drinking water chlorination, but much of it remains molecularly uncharacterized. Knowledge of model precursors is thus a prerequisite for understanding the more complex whole water DOM. The utility of HAA formation potential data from model DOM precursors, however, is limited due to the lack of comparability to water samples. In this study, the formation kinetics of dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA), the two predominant HAA species, were delineated upon chlorination of seventeen model DOM precursors and sixty-eight inland lake water samples collected from the Upper Midwest region of the United States. Of particular interest was the finding that the DCAA and TCAA formation rate constants could be grouped into four statistically distinct clusters reflecting the core structural features of model DOM precursors (i.e., non-β-diketone aliphatics, β-diketone aliphatics, non-β-diketone phenolics, and β-diketone phenolics). A comparative approach built upon hierarchical cluster analysis was developed to gain further insight into the chlorine reactivity patterns of HAA precursors in inland lake waters as defined by the relative proximity to four model precursor clusters. This work highlights the potential for implementing an integrated kinetic-clustering approach to constrain the chlorine reactivity of DOM in source waters. PMID:24299068

  15. Surface doping of nitrogen atoms on graphene via molecular precursor

    SciTech Connect

    Hong, Guo; Wu, Qi-Hui; Ren, Jianguo; Xu, Tingting; Center of Super-Diamond and Advanced Films , City University of Hong Kong, Hong Kong ; Wang, Chundong; Zhang, Wenjun; Lee, Shuit-Tong

    2013-02-04

    Surface doping can be a powerful way to modify the electronic properties of graphene with the unique potential to retain the excellent pristine properties of graphene. Here, we report an atomic surface doping method for graphene via dissociation of adsorbed precursor molecules of tetrafluorotetracyanoquinodimethane (F{sub 4}-TCNQ) induced by hydrogen plasma treatment. Significantly, the location of the dopant N atoms can be pre-determined by the location and orientation of the F{sub 4}-TCNQ molecule precursor on graphene, leading in principle to site-selective doping. Furthermore, the molecular precursor is stable under ambient conditions, satisfying an important consideration for patterning processes.

  16. High Tc superconducting films from metallo-organic precursors

    NASA Astrophysics Data System (ADS)

    Davison, W. W.; Shyu, S. G.; Buchanan, R. C.

    High Tc superconducting films of heavy metal soaps (derived from carboxylic acid precursors) have been prepared on Si and other substrates. The precursors were synthesized and mixed in appropriate molar ratios to form the high Tc compound YBa2Cu3O(7-x), using a high boiling point common solvent base. The precursor solution was deposited by a spin casting technique on the substrates. Film thicknesses of 0.1-1.0 micron were achieved after heat treatment at 550-850 C at not longer than 4 hours. Films were analyzed as to orientation, appropriate phase, interfacial reaction, and superconducting properties.

  17. Methods for forming particles from single source precursors

    DOEpatents

    Fox, Robert V.; Rodriguez, Rene G.; Pak, Joshua

    2011-08-23

    Single source precursors are subjected to carbon dioxide to form particles of material. The carbon dioxide may be in a supercritical state. Single source precursors also may be subjected to supercritical fluids other than supercritical carbon dioxide to form particles of material. The methods may be used to form nanoparticles. In some embodiments, the methods are used to form chalcopyrite materials. Devices such as, for example, semiconductor devices may be fabricated that include such particles. Methods of forming semiconductor devices include subjecting single source precursors to carbon dioxide to form particles of semiconductor material, and establishing electrical contact between the particles and an electrode.

  18. AN EVALUATION OF STRENGTHENING PRECURSORS TO INCREASE PRESCHOOLER COMPLIANCE

    PubMed Central

    Kraus, Aaron J; Hanley, Gregory P; Cesana, Lori L; Eisenberg, Danielle; Jarvie, Adam C

    2012-01-01

    We evaluated the strategy of increasing precursors to compliance on the compliance of 2 preschool boys. Modeling and differential reinforcement were used to increase specific responses to his name being called prior to the opportunity to comply with an instruction. The precursors were stopping the ongoing activity and orienting to, making eye contact with, and saying “yes” to the instructor. High levels of precursors occurred during treatment, and increases in compliance also were observed, even though the consequences for compliance and noncompliance did not change. PMID:22403455

  19. Search for GRB precursors in the Swift/BAT archive

    SciTech Connect

    Calderone, G.; Romano, P.; Mangano, V.; Cusumano, G.; Troja, E.

    2009-05-25

    Some GRBs are characterized by emission episodes occurring before the main event, called precursors. Their emission intensity is usually weaker than the GRB and is often comparable to (or slightly greater than) the background noise, making their detection difficult. We developed a code to automatically detect such precursors and applied it to a sample of 281 Swift/BAT GRBs. The identification procedure of precursor candidates uses a detection algorithm based on the wavelet transforms, and relies on an accurate study of the BAT background noise properties. A rigorous statistical approach is used for detection threshold settings and detection significance evaluation. We show the preliminary results of the analysis.

  20. The Xyrem risk management program.

    PubMed

    Fuller, David E; Hornfeldt, Carl S; Kelloway, Judy S; Stahl, Pamela J; Anderson, Todd F

    2004-01-01

    Sodium oxybate, also known as gamma-hydroxybutyric acid (GHB), was discovered in 1960 and has been described both as a therapeutic agent with high medical value and, more recently, a substance of abuse. The naturally occurring form of this drug is found in various body tissues but has been studied most extensively in the CNS where its possible function as a neurotransmitter continues to be studied. Sodium oxybate has been approved in different countries for such varied uses as general anaesthesia, the treatment of alcohol withdrawal and addiction, and, most recently, cataplexy associated with narcolepsy. During the 1980s, easy access to GHB-containing products led to various unapproved uses, including weight loss, bodybuilding and the treatment of sleeplessness, sometimes with serious long-term effects. The availability of these unapproved and unregulated forms of the drug led to GHB and its analogues being popularised as substances of abuse and subsequent notoriety as agents used in drug-facilitated sexual assault, or 'date rape', eventually leading to the prohibition of GHB sales in the US. Legal efforts to control the sale and distribution of GHB and its analogues nearly prevented the clinical development of sodium oxybate for narcolepsy in the US. However, following extensive discussions with a variety of interested parties, a satisfactory solution was devised, including legislative action and the development of the Xyrem Risk Management Program. Amendments to the US Controlled Substances Act made GHB a schedule I drug, but also contained provisions that allow US FDA-approved products to be placed under schedule III. This unique, bifurcated schedule for sodium oxybate/GHB allowed the clinical development of sodium oxybate to proceed and, in July 2002, it was approved by the FDA as an orphan drug for the treatment of cataplexy in patients with narcolepsy as Xyrem(sodium oxybate) oral solution. To promote the safe use of sodium oxybate, as well as alleviate concerns over possible diversion and abuse following product approval, a proprietary restricted drug distribution system was created, called the Xyrem Success Program. Components of the programme include a centralised distribution and dispensing system, a physician and patient registry, compulsory educational materials for patients and physicians, a specially trained pharmacy staff, a method for tracking prescription shipments, and an initial post-marketing surveillance programme. The system has created a unique opportunity to provide both physician and patient education and ongoing patient counselling, promoting greater drug safety and enhanced patient compliance. PMID:15061684

  1. [Felice Fontana precursor of neurosciences (author's transl)].

    PubMed

    Disertori, B; Piazza, M

    1981-01-01

    The A.A. insert the life and work of the naturalist and chemist Felice Fontana, born in Pomarolo (Trentino), in the frame of 18th century sciences, beside other great names of that century like Carolus Linnaeus, Réaumur, von Haller, Spallanzani, Morgagni, Priestley and Lavoisier. In the field of general biology, the discovery of nucleus and nucleolus and consequently the discovery of the eukaryotic cell, as we say in our days, in his, as well as the one of anabiosis. The A.A. enucleate and analyse the contributions of Fontana to the neurosciences; he has discovered the axon and the myelinic sheath half century before Remak and Purknije; he found out that the white matter of the brain is made of fibres alike those of nerves and the grey matter is made of globules (i.e. cells) mixed up with fibres; he discovered in the retina a part of coming out from the brain; he described the transversal bands of fibres of the skeletal muscles; he was the first to introduce into physiology the law of "all and nothing"; he attributed the irritability to the whole animal life; he identified the pupillar reflexes to the light, the reflex of accommodation, the consensual reflex, the psycho-emotive mydriasis and at last the myosis of sleep. He made experimental searches about nerves and recognised their regeneration, he enumerated various pathological intracranial masses, he made an important anatomopathological research about hydatid cyst in the brain of the sheep affected by "capostorno" and madness, he demonstrated their parasitical nature (he said that the hydated cysts were covered inside by small animals), he come out to formulate the hypothesis that some neuropsychiatric diseases of man can depend from similar aetiology. He declared that passions may have pathological effects (psyco-somatic aetiology), but he has also drawned the attention against the danager of aprioristical generalisation of neurogenical causes in all diseases. The A.A. give to Fontana the palm of precursor of modern neurosciences and of neurology intended as synthesis and unified corpus of these sciences. PMID:7041765

  2. Biological Indicators in Studies of Earthquake Precursors

    NASA Astrophysics Data System (ADS)

    Sidorin, A. Ya.; Deshcherevskii, A. V.

    2012-04-01

    Time series of data on variations in the electric activity (EA) of four species of weakly electric fish Gnathonemus leopoldianus and moving activity (MA) of two cat-fishes Hoplosternum thoracatum and two groups of Columbian cockroaches Blaberus craniifer were analyzed. The observations were carried out in the Garm region of Tajikistan within the frameworks of the experiments aimed at searching for earthquake precursors. An automatic recording system continuously recorded EA and DA over a period of several years. Hourly means EA and MA values were processed. Approximately 100 different parameters were calculated on the basis of six initial EA and MA time series, which characterize different variations in the EA and DA structure: amplitude of the signal and fluctuations of activity, parameters of diurnal rhythms, correlated changes in the activity of various biological indicators, and others. A detailed analysis of the statistical structure of the total array of parametric time series obtained in the experiment showed that the behavior of all animals shows a strong temporal variability. All calculated parameters are unstable and subject to frequent changes. A comparison of the data obtained with seismicity allow us to make the following conclusions: (1) The structure of variations in the studied parameters is represented by flicker noise or even a more complex process with permanent changes in its characteristics. Significant statistics are required to prove the cause-and-effect relationship of the specific features of such time series with seismicity. (2) The calculation of the reconstruction statistics in the EA and MA series structure demonstrated an increase in their frequency in the last hours or a few days before the earthquake if the hypocenter distance is comparable to the source size. Sufficiently dramatic anomalies in the behavior of catfishes and cockroaches (changes in the amplitude of activity variation, distortions of diurnal rhythms, increase in the mismatch of coordination between the activity dynamics of one type of biological indicators) were observed in one case before the November 12, 1987, event at a hypocenter distance of 8 km from the observation point (i.e., the animals were located within the source zone). (3) Changes observed before the earthquakes do not have any specific features and correspond quite well to the variations permanently observed without any relation to the earthquakes. (4) The activity of individual specimens has specific features. This hampers the implication of the biological monitoring. (5) The conclusions made here should not be considered absolute or extrapolated over all cases of observation of the behavior of animals, because the animals were kept under experimental (laboratory) conditions and could be screened from the influence of the stimuli of some modalities.

  3. MMPM - Mars MetNet Precursor Mission

    NASA Astrophysics Data System (ADS)

    Harri, A.-M.; Schmidt, W.; Pichkhadze, K.; Linkin, V.; Vazquez, L.; Uspensky, M.; Polkko, J.; Genzer, M.; Lipatov, A.; Guerrero, H.; Alexashkin, S.; Haukka, H.; Savijarvi, H.; Kauhanen, J.

    2008-09-01

    We are developing a new kind of planetary exploration mission for Mars - MetNet in situ observation network based on a new semi-hard landing vehicle called the Met-Net Lander (MNL). The eventual scope of the MetNet Mission is to deploy some 20 MNLs on the Martian surface using inflatable descent system structures, which will be supported by observations from the orbit around Mars. Currently we are working on the MetNet Mars Precursor Mission (MMPM) to deploy one MetNet Lander to Mars in the 2009/2011 launch window as a technology and science demonstration mission. The MNL will have a versatile science payload focused on the atmospheric science of Mars. Detailed characterization of the Martian atmospheric circulation patterns, boundary layer phenomena, and climatology cycles, require simultaneous in-situ measurements by a network of observation posts on the Martian surface. The scientific payload of the MetNet Mission encompasses separate instrument packages for the atmospheric entry and descent phase and for the surface operation phase. The MetNet mission concept and key probe technologies have been developed and the critical subsystems have been qualified to meet the Martian environmental and functional conditions. Prototyping of the payload instrumentation with final dimensions was carried out in 2003-2006.This huge development effort has been fulfilled in collaboration between the Finnish Meteorological Institute (FMI), the Russian Lavoschkin Association (LA) and the Russian Space Research Institute (IKI) since August 2001. Currently the INTA (Instituto Nacional de Tcnica Aeroespacial) from Spain is also participating in the MetNet payload development. To understand the behavior and dynamics of the Martian atmosphere, a wealth of simultaneous in situ observations are needed on varying types of Martian orography, terrain and altitude spanning all latitudes and longitudes. This will be performed by the Mars MetNet Mission. In addition to the science aspects the MetNet Mars Mission will provide a crucial support for the safety of large landing missions in general and manned Mars missions in particular. Accurate knowledge of atmospheric conditions and weather data is essential to guarantee safe landings of the forthcoming Mars mission elements. The MetNet Mars Mission is exactly this type of tool that is needed both for the Martian atmospheric science as well as for the mission safety issues.

  4. Field-test of a date-rape drug detection device.

    PubMed

    Quest, Dale W; Horsley, Joanne

    2007-01-01

    Drink Safe Technology Version 1.2 is an inexpensive color-change reagent test marketed internationally for use by consumers in settings such as a night club to detect potentially incapacitating concentrations of gamma-hydroxybutyric acid (GHB) and ketamine in beverages. The objective of this study was to compare product performance in the laboratory and performance in the hands of consumers in the field. Product performance in the laboratory adhered to the protocol defined by the manufacturer. Product performance in the hands of consumers in field settings allowed browsing participants to pipette an aliquot of their own drinks into randomly coded vials containing authentic drugs, or pure water, so as to yield the same concentrations of GHB or ketamine specified in the manufacturer-defined protocol, or blanks. Consumers were to proceed according to the directions printed on the product, and to record their results on a card with a code corresponding with the vial to which they had added an aliquot of their beverage. Diagnostic performance was calculated using two-way analysis. In the laboratory, Drink Safe Technology Version 1.2 reliably detected GHB and ketamine at concentrations specified by the manufacturer's protocol. The reactive color change denoting a positive test for GHB was rapid, but a positive test for ketamine required substantially more time to resolve. Nonetheless, test accuracy following the manufacturer's protocol in the laboratory was 100%. In the field, based on 101 paired-test results recorded by consumers, the test efficiency was 65.1%, sensitivity 50%, and specificity 91.6%. The product performed much better in the laboratory than it did in the hand of consumers in the field. There seems to be considerable potential for consumers to misinterpret a test result. The potential for consumers to record a false-negative test result for a spiked drink is cause for concern. PMID:17725882

  5. Insulin replacement restores the behavioral effects of quinpirole and raclopride in streptozotocin-treated rats.

    PubMed

    Sevak, Rajkumar J; Koek, Wouter; Galli, Aurelio; France, Charles P

    2007-03-01

    Streptozotocin (STZ)-induced diabetes can modulate dopamine (DA) neurotransmission and thereby modify the behavioral effects of drugs acting on DA systems. Insulin replacement, and in some conditions repeated treatment with amphetamine, can partially restore sensitivity of STZ-treated rats to dopaminergic drugs. The present study sought to characterize the role of insulin and amphetamine in modulating the behavioral effects of drugs that selectively act on D2/D3 receptors. In control rats, quinpirole and quinelorane produced yawning, whereas raclopride and gamma-hydroxybutyric acid (GHB) produced catalepsy. Raclopride antagonized quinpirole- and quinelorane-induced yawning with similar potency. STZ treatment increased blood glucose concentration, decreased body weight, and markedly reduced sensitivity to quinpirole-induced yawning, quinelorane-induced yawning as well as to raclopride-induced catalepsy, while enhancing sensitivity to GHB-induced catalepsy. Repeated treatment with amphetamine partially restored sensitivity of STZ-treated rats to amphetamine-stimulated locomotion and also produced conditioned place preference, without affecting blood glucose and body weight changes. However, amphetamine treatment did not restore sensitivity to the behavioral effects of quinpirole, raclopride, or GHB, suggesting differential regulation of dopamine transporter activity and sensitivity of D2 receptors in hypoinsulinemic rats. Insulin replacement in STZ-treated rats normalized blood glucose and body weight changes and fully restored sensitivity to quinpirole-induced yawning, as well as to raclopride-induced catalepsy, while reducing sensitivity to GHB-induced catalepsy. Overall, these data indicate that changes in insulin status markedly affect sensitivity to the behavioral effects of dopaminergic drugs. The results underscore the importance of insulin in modulating DA neurotransmission; these effects might be especially relevant to understanding the co-morbidity of eating disorders and substance abuse. PMID:17170311

  6. Liquid precursor for deposition of copper selenide and method of preparing the same

    SciTech Connect

    Curtis, Calvin J.; Miedaner, Alexander; Franciscus Antonius Maria Van Hest, Marinus; Ginley, David S.; Hersh, Peter A.; Eldada, Louay; Stanbery, Billy J.

    2015-09-08

    Liquid precursors containing copper and selenium suitable for deposition on a substrate to form thin films suitable for semiconductor applications are disclosed. Methods of preparing such liquid precursors and methods of depositing a precursor on a substrate are also disclosed.

  7. Precursor composites for oxygen dispersion hardened silver sheathed superconductor composites

    DOEpatents

    Podtburg, E.R.

    1999-06-22

    An oxide superconductor composite having improved texture and durability is disclosed. The oxide superconductor composite includes an oxide superconductor phase substantially surrounded with/by a noble metal matrix, the noble metal matrix comprising a metal oxide in an amount effective to form metal oxide domains that increase hardness of the composite. The composite is characterized by a degree of texture at least 10% greater than a comparable oxide superconductor composite lacking metal oxide domains. An oxide superconducting composite may be prepared by oxidizing the precursor composite under conditions effective to form solute metal oxide domains within the silver matrix and to form a precursor oxide in the precursor alloy phase; subjecting the oxidized composite to a softening anneal under conditions effective to relieve stress within the noble metal phase; and converting the oxide precursor into an oxide superconductor. 1 fig.

  8. Precursor composites for oxygen dispersion hardened silver sheathed superconductor composites

    DOEpatents

    Podtburg, Eric R.

    1999-01-01

    An oxide superconductor composite having improved texture and durability. The oxide superconductor composite includes an oxide superconductor phase substantially surrounded with/by a noble metal matrix, the noble metal matrix comprising a metal oxide in an amount effective to form metal oxide domains that increase hardness of the composite. The composite is characterized by a degree of texture at least 10% greater than a comparable oxide superconductor composite lacking metal oxide domains. An oxide superconducting composite may be prepared by oxidizing the precursor composite under conditions effective to form solute metal oxide domains within the silver matrix and to form a precursor oxide in the precursor alloy phase; subjecting the oxidized composite to a softening anneal under conditions effective to relieve stress within the noble metal phase; and converting the oxide precursor into an oxide superconductor.

  9. MULTIPOLLUTANT METHODS - METHODS FOR OZONE AND OZONE PRECURSORS

    EPA Science Inventory

    This task involves the development and testing of methods for monitoring ozone and compounds associated with the atmospheric chemistry of ozone production both as precursors and reaction products. Although atmospheric gases are the primary interest, separation of gas and particl...

  10. Ab initio characterization of graphene nanoribbons and their polymer precursors

    NASA Astrophysics Data System (ADS)

    Peköz, Rengin; Feng, Xinliang; Donadio, Davide

    2012-03-01

    Bottom-up fabrication of graphene nanoribbons (GNRs) from halogen-terminated aromatic precursors is a promising method for achieving atomically precise nanoribbons at competitive yields. GNR fabrication proceeds via the polymerization of the precursors and successive dehydrogenation. By first principles density functional theory calculations, we perform a systematic characterization of the polymeric precursors and the corresponding graphene nanoribbons in terms of structural and electronic properties, and we compute the Raman and infrared spectra. The band structure properties are examined by considering the bonding features and the partial charge densities of the structures. The physical origin of the infrared and Raman peaks is investigated in terms of the morphology and vibrational properties of the precursors and products. We show that light spectroscopy provides a unique fingerprint for each type of GNR, which may be used to monitor the quality of the final products and the kinetics of the synthesis process.

  11. Precursor candidacy and validation: The VAN Case so far

    NASA Astrophysics Data System (ADS)

    Mulargia, Francesco; Gasperini, Paolo

    A reliable identification of seismic precursors requires a two-step statistical approach: a retrospective “learning” step to establish the candidate precursors on the basis of ad hoc chosen laws of the game, and a “validation” step which evaluates candidate precursors on an independent data set according to the previously established laws of the game. No published work has so far provided a sound support to the candidacy of the VAN signals as earthquake precursors. The problem is complicated by a chronic fuzziness in the text of VAN's predictions, which often allows different interpretations, and by the absence of any clear statement by VAN of the laws of the game.

  12. Quarternary Amines as Nitrosamine Precursors: A Role for Consumer Products?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrosamine formation is associated with wastewater-impacted water supplies, but the specific precursors within municipal wastewater effluents have not been identified. Quaternary amines are significant constituents of consumer products, including shampoos, detergents and fabric softeners. Experimen...

  13. Explorations Precursor Robotic Missions (xPRM) - Duration: 44 minutes.

    NASA Video Gallery

    Jay Jenkins delivers a presentation from the Exploration Precursor Robotic Missions (xPRM) study team on May 25, 2010, at the NASA Exploration Enterprise Workshop held in Galveston, TX. The purpose...

  14. Improved Single-Source Precursors for Solar-Cell Absorbers

    NASA Technical Reports Server (NTRS)

    Banger, Kulbinder K.; Harris, Jerry; Hepp, Aloysius

    2007-01-01

    Improved single-source precursor compounds have been invented for use in spray chemical vapor deposition (spray CVD) of chalcopyrite semiconductor absorber layers of thin-film cells. A "single-source precursor compound" is a single molecular compound that contains all the required elements, which when used under the spray CVD conditions, thermally decomposes to form CuIn(x)Ga(1-x)S(y)Se(2-y).

  15. Evolution and ultrastructure of the bovine spermatogonia precursor cell line.

    PubMed

    Wrobel, K H; Bickel, D; Kujat, R; Schimmel, M

    1995-08-01

    The spermatogonial stem cell line in prepubertal and adult bovine testis was studied by electron microscopy and protein gene product 9.5 immunohistochemistry. Three successive spermatogonia precursor cell configurations were observed. Small basal stem cells were found to possess a spherical shape and nuclei with two to three nucleoli. They were observed in prepubertal testes (25 and 30 weeks) and in low numbers during all the stages of the seminiferous epithelial cycle in the adult. Aggregated spermatogonia precursor cells are the dominating germ cell type in the 25-week-old and 30-week-old calf. In the adult seminiferous epithelium, they cause expansion of the basal tubular compartment as they form dense groups containing up to 15 cells. These groups are observed concomitantly with cycling A-spermatogonia and preleptotenes at the beginning of spermatocytogenesis. At the end of A-spermatogonia propagation, the aggregated spermatogonia precursor cells separate and intermingle with cycling A-spermatogonia. The spermatogonia precursor cells can later be found together with I-spermatogonia as members of an interconnected cellular network of medium-sized cells. When the I-spermatogonia divide to form the smaller B-spermatogonia, the precursor cells, which stay connected with the cycling spermatogonial population, pass through a growth phase. They can now be considered as committed spermatogonia precursor cells and are continuously being transformed into A1-spermatogonia to start a new round of spermatocytogenesis. Ultrastructurally, all members of the precursor cell line are similar. However, a number of features have been found to show a quantitative increase (endoplasmic reticulum, mitochondria) or to exhibit a rising degree of complexity (nucleolus) during the progression from basal stem cells to committed spermatogonia precursor cells. PMID:7648620

  16. Search for Precursor Eruptions among Type IIb Supernovae

    NASA Astrophysics Data System (ADS)

    Strotjohann, Nora L.; Ofek, Eran O.; Gal-Yam, Avishay; Sullivan, Mark; Kulkarni, Shrinivas R.; Shaviv, Nir J.; Fremling, Christoffer; Kasliwal, Mansi M.; Nugent, Peter E.; Cao, Yi; Arcavi, Iair; Sollerman, Jesper; Filippenko, Alexei V.; Yaron, Ofer; Laher, Russ; Surace, Jason

    2015-10-01

    The progenitor stars of several Type IIb supernovae (SNe) show indications of extended hydrogen envelopes. These envelopes might be the outcome of luminous energetic pre-explosion events, so-called precursor eruptions. We use the Palomar Transient Factory (PTF) pre-explosion observations of a sample of 27 nearby SNe IIb to look for such precursors during the final years prior to the SN explosion. No precursors are found when combining the observations in 15-day bins, and we calculate the absolute-magnitude-dependent upper limit on the precursor rate. At the 90% confidence level, SNe IIb have on average <0.86 precursors as bright as an absolute R-band magnitude of -14 in the final 3.5 years before the explosion and <0.56 events over the final year. In contrast, precursors among SNe IIn have a ≳5 times higher rate. The kinetic energy required to unbind a low-mass stellar envelope is comparable to the radiated energy of a few-weeks-long precursor that would be detectable for the closest SNe in our sample. Therefore, mass ejections, if they are common in such SNe, are radiatively inefficient or have durations longer than months. Indeed, when using 60-day bins, a faint precursor candidate is detected prior to SN 2012cs (˜2% false-alarm probability). We also report the detection of the progenitor of SN 2011dh that does not show detectable variability over the final two years before the explosion. The suggested progenitor of SN 2012P is still present, and hence is likely a compact star cluster or an unrelated object.

  17. Precursors for the polymer-assisted deposition of films

    DOEpatents

    McCleskey, Thomas M.; Burrell, Anthony K.; Jia, Quanxi; Lin, Yuan

    2013-09-10

    A polymer assisted deposition process for deposition of metal oxide films is presented. The process includes solutions of one or more metal precursor and soluble polymers having binding properties for the one or more metal precursor. After a coating operation, the resultant coating is heated at high temperatures to yield metal oxide films. Such films can be epitaxial in structure and can be of optical quality. The process can be organic solvent-free.

  18. Rb suppresses human cone-precursor-derived retinoblastoma tumours.

    PubMed

    Xu, Xiaoliang L; Singh, Hardeep P; Wang, Lu; Qi, Dong-Lai; Poulos, Bradford K; Abramson, David H; Jhanwar, Suresh C; Cobrinik, David

    2014-10-16

    Retinoblastoma is a childhood retinal tumour that initiates in response to biallelic RB1 inactivation and loss of functional retinoblastoma (Rb) protein. Although Rb has diverse tumour-suppressor functions and is inactivated in many cancers, germline RB1 mutations predispose to retinoblastoma far more strongly than to other malignancies. This tropism suggests that retinal cell-type-specific circuitry sensitizes to Rb loss, yet the nature of the circuitry and the cell type in which it operates have been unclear. Here we show that post-mitotic human cone precursors are uniquely sensitive to Rb depletion. Rb knockdown induced cone precursor proliferation in prospectively isolated populations and in intact retina. Proliferation followed the induction of E2F-regulated genes, and depended on factors having strong expression in maturing cone precursors and crucial roles in retinoblastoma cell proliferation, including MYCN and MDM2. Proliferation of Rb-depleted cones and retinoblastoma cells also depended on the Rb-related protein p107, SKP2, and a p27 downregulation associated with cone precursor maturation. Moreover, Rb-depleted cone precursors formed tumours in orthotopic xenografts with histological features and protein expression typical of human retinoblastoma. These findings provide a compelling molecular rationale for a cone precursor origin of retinoblastoma. More generally, they demonstrate that cell-type-specific circuitry can collaborate with an initiating oncogenic mutation to enable tumorigenesis. PMID:25252974

  19. Plasma spray synthesis from precursors: Progress, issues, and considerations

    NASA Astrophysics Data System (ADS)

    Ravi, B. G.; Sampath, S.; Gambino, R.; Parise, J. B.; Devi, P. S.

    2006-12-01

    Precursor plasma spray synthesis is an innovative and rapid method for making functional oxide ceramic coatings by starting from solution precursors and directly producing inorganic films. This emerging method utilizes molecularly mixed precursor liquids, which essentially avoids the handling and selection of powders, opening up new avenues for developing compositionally complex functional oxide coatings. Precursor plasma spray also offers excellent opportunities for exploring the nonequilibrium phase evolution during plasma spraying of multicomponent oxides from inorganic precursors. Although there have been efforts in this area since the 1980s and early 1990s with the goal of synthesizing nanoparticles, only recently has the work progressed in the area of functional systems. At the Center for Thermal Spray Research an integrated investigative strategy has been used to explore the benefits and limits of this synthesis strategy. Water- and alcohol-based sol/solution precursors derived from various chemical synthesis methods were used as feedstocks to deposit thin/thick films of spherical and nanostructured coatings of yttrium aluminum garnet (YAG), yttrium iron garnet, lanthanum strontium manganate and Zr-substituted yttrium titanates, and compositions of Y2O3-Al2O3 and their microstructural space centered around stoichiometric YAG. A detailed discussion of the salient features of the radiofrequency induction plasma spraying approach, the results obtained in the investigations to develop various functional oxide coatings, and process issues and challenges are presented.

  20. Detection of hydrogeochemical seismic precursors by a statistical learning model

    NASA Astrophysics Data System (ADS)

    Castellana, L.; Biagi, P. F.

    2008-11-01

    The problem of detecting the occurrence of an earthquake precursor is faced in the general framework of the statistical learning theory. The aim of this work is both to build models able to detect seismic precursors from time series of different geochemical signals and to provide an estimate of number of false positives. The model we used is k-Nearest-Neighbor classifier for discriminating "no-disturbed signal", "seismic precursor" and "co-post seismic precursor" in time series relative to thirteen different hydrogeochemical parameters collected in water samples from a natural spring in Kamchachta (Russia) peninsula. The measurements collected are ion content (Na, Cl, Ca, HCO3, H3BO3), parameters (pH, Q, T) and gases (N2, CO2, CH4, O2, Ag). The classification error is measured by Leave-K-Out-Cross-Validation procedure. Our study shows that the most discriminative ions for detecting seismic precursors are Cl and Na having an error rates of 15%. Moreover, the most discriminative parameters and gases are Q and CH4 respectively, with error rate of 21%. The ions result the most informative hydrogeochemicals for detecting seismic precursors due to the peculiarities of the mechanisms involved in earthquake preparation. Finally we show that the information collected some month before the event under analysis are necessary to improve the classification accuracy.

  1. Precursor polymer effect on polyimide/silica hybrid nanocomposite films.

    PubMed

    Kim, Youngkyoo; Ha, Chang-Sik; Chang, Taehyun; Lee, Won-Ki; Goh, Wanhee; Kim, Hwajeong; Ha, Youri; Ree, Moonhor

    2009-08-01

    Here we report the influence of the polyimide precursor type on the surface morphology and properties of poly(p-phenylene biphenyltetracarboximide) (BPDA-PDA PI)/silica hybrid composite films. Two types of precursor polymer were employed: poly(p-phenylene biphenyltetracarboxamic acid) (BPDA-PDA PAA) and poly(p-phenylene biphenyltetracarboxamic diethyl ester) (BPDA-PDA PES). These precursor polymers were mixed with tetraethoxysilane in the presence of HCl and H2O, which led to the precursor mixture films that contain in-situ generated silica particles via sol-gel process. Then the precursor mixture films were subject to thermal imidization to make polyimide/silica hybrid composite films. Results showed that the PAA precursor has better compatibility with silica particles, which is mainly attributed to the early making of silyl ester bonds (as evidenced by X-ray photoelectron spectroscopy) between carboxylic acid groups in the PAA and hydroxyl groups in silanol molecules. Further evidences were provided by the measurement of surface nanomorphology, crystal nanostructure, thermal/mechanical properties, and optical birefringence. PMID:19928128

  2. Elements of the tsunami precursors' detection physics

    NASA Astrophysics Data System (ADS)

    Novik, Oleg; Ruzhin, Yuri; Ershov, Sergey; Volgin, Max; Smirnov, Fedor

    In accordance with the main physical principles and geophysical data, we formulated a nonlinear mathematical model of seismo-hydro-electromagnetic (EM) geophysical field interaction and calculated generation and propagation of elastic, EM, temperature and hydrodynamic seismically generated disturbances (i.e. signals) in the basin of a marginal sea. We show transferring of seismic and electromagnetic (EM) energy from the upper mantle beneath the sea into its depths and EM emission from the sea surface into the atmosphere. Basing on the calculated characteristics of the signals of different physical nature (computations correspond to measurements of other authors) we develop the project of a Lithosphere-Ocean-Atmosphere Monitoring System (LOAMS) including: a bottom complex, a moored ocean surface buoy complex, an observational balloon complex, and satellite complex. The underwater stations of the bottom complex of the LOAMS will record the earlier signals of seismic activation beneath a seafloor (the ULF EM signals outrun seismic ones, according to the above calculations) and localize the seafloor epicenter of an expected seaquake. These stations will be equipped, in particular, with: magnetometers, the lines for the electric field measurements, and magneto-telluric blocks to discover dynamics of physical parameters beneath a sea floor as signs of a seaquake and/or tsunami preparation process. The buoy and balloon complexes of the LOAMS will record the meteorological and oceanographic parameters' variations including changes of reflection from a sea surface (tsunami ‘shadows’) caused by a tsunami wave propagation. Cables of the balloon and moored buoy will be used as receiving antennas and for multidisciplinary measurements including gradients of the fields (we show the cases are possible when the first seismic EM signal will be registered by an antenna above a sea). Also, the project includes radio-tomography with satellite instrumentation and sounding of the ionosphere from the buoy, balloon and satellite complexes. The balloon and buoy complexes will transmit data to a shore station over satellite link. The frequency ranges and sensitivity thresholds of all of the sensors of the LOAMS will be adapted to the characteristics of expected seismic signals according to the numerical research above. Computational methods and statistical analysis (e.g. seismic changes of coherence of spatially distributed sensors of different nature) of the recorded multidimensional time series will be used for prognostic interpretation. The multilevel recordings will provide a stable noise (e.g. ionosphere Pc pulsations, hard sea, industry) and seismic event detection. An intensive heat flow typical for tectonically active lithosphere zones may be considered as an energy source for advanced modifications of the LOAMS. The latter may be used as a warning system for continental and marine technologies, e.g. a sea bottom geothermal energy production. Indeed, seismic distraction of the nuclear power station Fukushima I demonstrates that similar technology hardly is able to solve the energy problems in seismically active regions. On the other hand, the LOAMS may be considered as a scientific observatory for development of the seaquake/tsunami precursor physics, i.e. seismo-hydro-electromagnetics.

  3. Disodium diselenide in colloidal nanocrystals: acting as an anion exchange precursor, a metal selenide precursor, and a chalcogenide ligand.

    PubMed

    Choi, Donghyeuk; Lee, Seungyeol; Lee, Junho; Cho, Kyung-Sang; Kim, Sang-Wook

    2015-01-18

    A new application area using a very simple alkali metal chalcogenide, disodium diselenide (Na2Se2), has been developed. The prepared alkali metal chalcogenide (disodium diselenide, Na2Se2) acts as an anionic exchange precursor (PbS to PbS-PbSe), a Se precursor for metal selenide nanoparticles (Ag to Ag2Se), and a MCC (FeO-MCC) depending on the type of colloidal nanoparticles. PMID:25431810

  4. Predicting Solar Cycle 24 Using a Geomagnetic Precursor Pair

    NASA Technical Reports Server (NTRS)

    Pesnell, W. Dean

    2014-01-01

    We describe using Ap and F(10.7) as a geomagnetic-precursor pair to predict the amplitude of Solar Cycle 24. The precursor is created by using F(10.7) to remove the direct solar-activity component of Ap. Four peaks are seen in the precursor function during the decline of Solar Cycle 23. A recurrence index that is generated by a local correlation of Ap is then used to determine which peak is the correct precursor. The earliest peak is the most prominent but coincides with high levels of non-recurrent solar activity associated with the intense solar activity of October and November 2003. The second and third peaks coincide with some recurrent activity on the Sun and show that a weak cycle precursor closely following a period of strong solar activity may be difficult to resolve. A fourth peak, which appears in early 2008 and has recurrent activity similar to precursors of earlier solar cycles, appears to be the "true" precursor peak for Solar Cycle 24 and predicts the smallest amplitude for Solar Cycle 24. To determine the timing of peak activity it is noted that the average time between the precursor peak and the following maximum is approximately equal to 6.4 years. Hence, Solar Cycle 24 would peak during 2014. Several effects contribute to the smaller prediction when compared with other geomagnetic-precursor predictions. During Solar Cycle 23 the correlation between sunspot number and F(10.7) shows that F(10.7) is higher than the equivalent sunspot number over most of the cycle, implying that the sunspot number underestimates the solar-activity component described by F(10.7). During 2003 the correlation between aa and Ap shows that aa is 10 % higher than the value predicted from Ap, leading to an overestimate of the aa precursor for that year. However, the most important difference is the lack of recurrent activity in the first three peaks and the presence of significant recurrent activity in the fourth. While the prediction is for an amplitude of Solar Cycle 24 of 65 +/- 20 in smoothed sunspot number, a below-average amplitude for Solar Cycle 24, with maximum at 2014.5+/-0.5, we conclude that Solar Cycle 24 will be no stronger than average and could be much weaker than average.

  5. Cyanogen chloride precursor analysis in chlorinated river water.

    PubMed

    Lee, Jun Hee; Na, Chongzheng; Ramirez, Roberto L; Olson, Terese M

    2006-03-01

    Amino acids have been cited as potential precursors of the disinfection byproduct cyanogen chloride in chlorinated drinking water. Screening experiments with 17 amino acids were performed in this study to comprehensively identify important CNCl precursors. Among this set, only glycine was found to yield detectable CNCl (i.e., > 0.6% yields). Additional experiments were conducted to estimate the relative significance of glycine as a CNCI precursor in water samples collected from the Huron River, Michigan, by concurrently characterizing the amino acid content and monitoring CNCI yields after chlorination. Chlorine was added at slightly less than the sample breakpoint dose to optimize CNCl formation and stability in the samples. On the basis of previous determinations that glycine-nitrogen is stoichiometrically converted to CNCI-N at pH > 6, it was estimated that glycine may account for 42-45% of the CNCI formed in the river water samples (pH 8.2). The kinetic profile of CNCl formation in the sample, with a half-life of about 20 min, indicated that both rapid and slower formation pathways were important. Glycine formation of CNCl, with a half-life of 4 min, is likely to contribute significantly to the rapidly formed CNCI, while unidentified precursors must accountfor the slower pathway. Non-glycine-derived CNCl precursors in this water source were further examined to determine if they were largely proteinaceous in character using a technique known as immobilized metal ion affinity chromatography (IMAC). These experiments demonstrated that copper-loaded IMAC resins were much more effective in removing glycine than other CNCI precursor compounds in the sample matrix. The unidentified CNCI precursor components, therefore, are not likely to be proteinaceous and are more likely to be associated with the fulvic/humic fraction of organic matter. PMID:16568759

  6. Anise oil as para-methoxyamphetamine (PMA) precursor.

    PubMed

    Waumans, Dieter; Bruneel, Noël; Tytgat, Jan

    2003-04-23

    These days, MDMA is one of the most popular drugs of abuse. Due to its illegality, MDMA and its chemical precursors are watched by governmental organizations in many countries. To avoid conflicts with legal instances, underground chemists have tried to market several new unregulated amphetamine analogues, such as 4-MTA. Para-methoxyamphetamine (PMA), on the other hand, is regulated by law but its precursors are easily obtained since they are cheap and unwatched. This article presents such a case, namely the large scale synthesis of PMA using anethole, a main constituent of anise oil, as precursor. Anethole has been converted to its phenyl acetone analogue via peracid oxidation, while PMA itself has been synthesized using this ketone as precursor in the Leuckart synthesis. The synthesis of PMA using anethole as starting product has been investigated applying GC/MS and GC-HSPME/MS techniques, hereby discovering new specific (4-methoxyphenol) and already identified synthesis impurities (4-methyl-5-(4-methoxyphenyl)pyrimidine, N-(beta-4-methoxyphenylisopropyl)-4-methoxybenzyl methyl ketimine, 1-(4-methoxyphenyl)-N-(2-(4-methoxyphenyl)-1-methylethyl-2-propanamine, 1-(4-methoxyphenyl)-N-methyl-N-(2-(4-methoxyphenyl)-1-methylethyl-2-propanamine, N-(beta-4-methoxyphenylisopropyl)-4-methoxybenzaldimine). The new impurity 4-methoxyphenol is specific for the application of a peracid oxidation method where anethole is used as precursor. PMID:12742705

  7. Subcellular Distribution of Glutathione Precursors in Arabidopsis thaliana

    PubMed Central

    Koffler, Barbara Eva; Maier, Romana; Zechmann, Bernd

    2011-01-01

    Abstract Glutathione is an important antioxidant and has many important functions in plant development, growth and defense. Glutathione synthesis and degradation is highly compartment-specific and relies on the subcellular availability of its precursors, cysteine, glutamate, glycine and γ-glutamylcysteine especially in plastids and the cytosol which are considered as the main centers for glutathione synthesis. The availability of glutathione precursors within these cell compartments is therefore of great importance for successful plant development and defense. The aim of this study was to investigate the compartment-specific importance of glutathione precursors in Arabidopsis thaliana. The subcellular distribution was compared between wild type plants (Col-0), plants with impaired glutathione synthesis (glutathione deficient pad2-1 mutant, wild type plants treated with buthionine sulfoximine), and one complemented line (OE3) with restored glutathione synthesis. Immunocytohistochemistry revealed that the inhibition of glutathione synthesis induced the accumulation of the glutathione precursors cysteine, glutamate and glycine in most cell compartments including plastids and the cytosol. A strong decrease could be observed in γ-glutamylcysteine (γ-EC) contents in these cell compartments. These experiments demonstrated that the inhibition of γ-glutamylcysteine synthetase (GSH1) – the first enzyme of glutathione synthesis – causes a reduction of γ-EC levels and an accumulation of all other glutathione precursors within the cells. PMID:22050910

  8. A novel class of peptide pheromone precursors in ascomycetous fungi

    PubMed Central

    Schmoll, Monika; Seibel, Christian; Tisch, Doris; Dorrer, Marcel; Kubicek, Christian P

    2010-01-01

    Recently, sexual development in the heterothallic ascomycete Trichoderma reesei (anamorph of Hypocrea jecorina) has been achieved and thus initiated attempts to elucidate regulation and determinants of this process. While the α-type pheromone of this fungus fits the consensus known from other fungi, the assumed a-type peptide pheromone precursor shows remarkably unusual characteristics: it comprises three copies of the motif (LI)GC(TS)VM thus constituting a CAAX domain at the C-terminus and two Kex2-protease sites. This structure shares characteristics of both a- and α-type peptide pheromone precursors. Presence of hybrid-type peptide pheromone precursor 1 (hpp1) is essential for male fertility, thus indicating its functionality as a peptide pheromone precursor, while its phosphorylation site is not relevant for this process. However, sexual development in a female fertile background is not perturbed in the absence of hpp1, which rules out a higher order function in this process. Open reading frames encoding proteins with similar characteristics to HPP1 were also found in Fusarium spp., of which Fusarium solani still retains a putative a-factor-like protein, but so far in no other fungal genome available. We therefore propose the novel class of h-type (hybrid) peptide pheromone precursors with H. jecorina HPP1 as the first member of this class. PMID:20735770

  9. Thin film solar cells by selenization sulfurization using diethyl selenium as a selenium precursor

    DOEpatents

    Dhere, Neelkanth G.; Kadam, Ankur A.

    2009-12-15

    A method of forming a CIGSS absorber layer includes the steps of providing a metal precursor, and selenizing the metal precursor using diethyl selenium to form a selenized metal precursor layer (CIGSS absorber layer). A high efficiency solar cell includes a CIGSS absorber layer formed by a process including selenizing a metal precursor using diethyl selenium to form the CIGSS absorber layer.

  10. Experimental observation of precursor solitons in a flowing complex plasma

    NASA Astrophysics Data System (ADS)

    Jaiswal, Surabhi; Bandyopadhyay, P.; Sen, A.

    2016-04-01

    The excitation of precursor solitons ahead of a rapidly moving object in a fluid, a spectacular phenomenon in hydrodynamics that has often been observed ahead of moving ships, has surprisingly not been investigated in plasmas where the fluid model holds good for low frequency excitations such as ion acoustic waves. In this Rapid Communication we report an experimental observation of precursor solitons in a flowing dusty plasma. The nonlinear solitary dust acoustic waves (DAWs) are excited by a supersonic mass flow of the dust particles over an electrostatic potential hill. In a frame where the fluid is stationary and the hill is moving the solitons propagate in the upstream direction as precursors while wake structures consisting of linear DAWs are seen to propagate in the downstream region. A theoretical explanation of these excitations based on the forced Korteweg-deVries model equation is provided and their practical implications in situations involving a charged object moving in a plasma are discussed.

  11. Are hypothyroidism and iron deficiency precursor cell diseases?

    PubMed

    Mayer-Pröschel, M; Morath, D; Noble, M

    2001-01-01

    It is neither known why hormonal and nutritional deficiencies only cause neurological abnormalities at particular periods of development, nor is it known why repair only occurs if normal metabolic status is restored within a particular temporal window. We propose that these maladies are precursor cell diseases, in which the normal balance between self-renewal and differentiation is compromised in dividing precursor cells. According to this hypothesis, the windows of vulnerability in these disorders correspond to the timing of particular transitions in CNS precursor cells, as seen in our studies on the effects of thyroid hormone and iron on the generation of oligodendrocytes and their immediate ancestor, the O-2A progenitor cell. PMID:11756743

  12. Mechanisms of Gravitational Sensitivity of Osteogenic Precursor Cells

    PubMed Central

    Buravkova, L.B.; Gershovich, P.M.; Grigorʹev, A.I.

    2010-01-01

    This report is a detailed review of the current data on the mechanic and gravitational sensitivity of osteoblasts and osteogenic precursor cells in vitro. It summarizes the numerous responses of cells with an osteoblastic phenotype and osteogenic precursor cells and especially their responses to the alteration of their mechanic or gravitational surroundings. The review also discusses the osteogenic cell’s pathways of signal transduction and the mechanisms of gravitational sensitivity. It was shown that the earliest multipotent stromal precursor cells of an adult organism’s bone marrow can sense changes of intensity in a gravitational or mechanic field in model conditions, which may play a certain role in the development of osteopenia in microgravity. PMID:22649626

  13. Transition Metal Dichalcogenide Growth via Close Proximity Precursor Supply

    PubMed Central

    O'Brien, Maria; McEvoy, Niall; Hallam, Toby; Kim, Hye-Young; Berner, Nina C.; Hanlon, Damien; Lee, Kangho; Coleman, Jonathan N.; Duesberg, Georg S.

    2014-01-01

    Reliable chemical vapour deposition (CVD) of transition metal dichalcogenides (TMDs) is currently a highly pressing research field, as numerous potential applications rely on the production of high quality films on a macroscopic scale. Here, we show the use of liquid phase exfoliated nanosheets and patterned sputter deposited layers as solid precursors for chemical vapour deposition. TMD monolayers were realized using a close proximity precursor supply in a CVD microreactor setup. A model describing the growth mechanism, which is capable of producing TMD monolayers on arbitrary substrates, is presented. Raman spectroscopy, photoluminescence, X-ray photoelectron spectroscopy, atomic force microscopy, transmission electron microscopy, scanning electron microscopy and electrical transport measurements reveal the high quality of the TMD samples produced. Furthermore, through patterning of the precursor supply, we achieve patterned growth of monolayer TMDs in defined locations, which could be adapted for the facile production of electronic device components. PMID:25487822

  14. Effect of precursor solution dark incubation on gold nanorods morphology

    NASA Astrophysics Data System (ADS)

    Abdelrasoul, Gaser N.; Scotto, Marco; Cingolani, Roberto; Diaspro, Alberto; Athanassiou, Athanassia; Pignatelli, Francesca

    2012-12-01

    Gold nanorods were synthesized in an aqueous solution of hexadecyltrimethylammonium bromide via a combination of chemical reduction and UV photoirradiation. Gold ligand complexes, present in the stock solution, are initially reduced, by ascorbic acid as mild reducing agent. The gold ions nucleation and colloid growth proceeds then by subsequent UV irradiation of the so-obtained precursor solution. We present a systematic study of the effect of incubation of the precursor solution on the dispersion state and aspect ratio of the produced nanorods. Incubation of the precursor solution allows the synthesis of higher aspect ratio nanorods with narrower size distribution compared to those obtained without incubation. We propose a mechanism for the gold nanorods formation including two stages, a nucleation and a diffusive growth. This allows us to explain the synthesis improvement as a consequence of the increase in the size of the gold ligand complexes aggregates, leading to a decrease of the nanorods growth rate.

  15. Research of Hydro-Geological Precursors of Earthquakes in Armenia

    NASA Astrophysics Data System (ADS)

    Pashayan, R.

    2007-12-01

    The observations of hydro-geological regime of underground waters in observed boreholes began in Armenia in 1986. Now these work is concentrated in National Seismic Service. For a long time observations are carried out studying several parameters (debit, temperature, chemical and gas composition) in several deposits of carbon mineral waters of Armenia. The interpretation of materials shows that that a number of strong and medium-strength earthquakes are accompanied by anomal changes in the level of underground waters. Regarding mineral waters, in connection with earthquakes some parameters are immediately changed: debit, temperature, chemical and gas composition. The study of hydrogeodynamic characteristics of precursors specify that the quantity of registered hydrogeodynamic precursors decreases with the increase of epicentrical distance. The majority of precursors is registered at the distance of 200 km from epicenter. There is a tendency of gradual increase of time and amplitude of a precursor of an earthquake depending on the rise of magnitude and epicentral distance. The behaviour of hydrogeodynamic precursors depends on the angle between the faults, to which this or that borehole reaches; with increase of this angle the deformation in the zone of the fault during the preparation of earthquakes is stronger, than in terms of small angles. 1. S1 2. Earthquake processes, Precursors and Forecasts 3. Garni Geophysical Observatory of the National Academy of Sciences of Armenia, 375019, Yerevan, Republic of Armenia, email: hakhleon@sci.am 4. O 5. 10808801 6. Artavazd Payment Type: select 'Purchase Order' PO Number: AGU WAIVER Billing Address: Enter Your Institution City: Enter Your City Country Code: Enter Your Country Name: Enter Your Name Phone: Enter Your Telephone Number

  16. The behaviors of optimal precursors during wintertime Eurasian blocking onset

    NASA Astrophysics Data System (ADS)

    Jiang, Zhina; Wang, Donghai

    2012-11-01

    In this paper the optimal precursors for wintertime Eurasian blocking onset are acquired by solving a nonlinear optimization problem whose objective function is constructed based on a blocking index with a triangular T21, three-level, quasi-geostrophic global spectral model. The winter climatological state is chosen as the reference basic state. Numerical results show that the optimal precursors are characterized by a baroclinic pattern with a westward tilt with height, which are mainly located upstream of the blocking region. For an optimization time of 5 days, these perturbations are mainly localized over the Northeast Atlantic Ocean and continental Europe. With the extension of the optimization time to 8 days, these perturbations are distributed more upstream and extensively in the zonal direction. Wave spectrum analysis reveals that the optimal precursors are composed of not only synoptic-scale (wave numbers 5-18) waves, but planetary-scale (wave numbers 0-4) waves as well. The synoptic-scale optimal precursors are mainly located in the mid-latitude area, while the planetary-scale optimal precursors focus primarily on the high-latitude region. The formation of a strong planetary-scale positive blocking anomaly is accompanied by the reinforcement of synoptic-scale perturbations and further fragmentation into two branches, in which the northern branch is generally stronger than the southern one. The eddy forcing arising from the self-interaction of synoptic-scale disturbances is shown to be crucial in triggering the dipole blocking anomaly, and the planetary-scale optimal precursor provides the initial favorable background conditions for blocking onset.

  17. Precursor Exploration Missions in Kelly Lake, British Columbia- MARSLIFE project

    NASA Astrophysics Data System (ADS)

    Trembanis, A. C.; Gutsche, J.; Nebel, S. H.

    2010-12-01

    Precursor missions are an integral step in coordinated exploration between unmanned and manned systems both for terrestrial and astrobiology applications. Testing and developing the protocols for efficient, safe, and meaningful precursor missions is a key step in readiness for space exploration and is integral to the new MARSLIFE analogue research project. Here we present first-year field results from the use of an autonomous underwater vehicle (AUV) to conduct high-resolution (<1 m/pixel) geoacoustic mapping (bathymetry and backscatter) of the MARSLIFE field site. Rapid operations and quick-turn-around data-processing (within 1 - 2 days) allowed us to provide our precursor mission data in the form of digital maps to the MARSLIFE operating team for site assessment and mission planning. Precursor mapping helped identify target areas for specific operations, including ROV and Deepworker missions during the field campaign. Mission critical results from the AUV survey included morphology (micro-bathymetry), target localization, and suitability of terrain types based on slope and rugosity for different mission activities (e.g. SCUBA slope transects and water samples). The rapid acquisition and data processing turn around allowed us to provide mission critical measurements such as depth, slope, composition, and roughness to the entire exploration team. In total during the July 2010 field campaign, over 3 days of intensive AUV and ROV missions were run in Kelly Lake resulting in nearly 50 km of trackline data (side-scan sonar, swath bathymetry, color video, and water quality measurements) of the lake at sub-meter resolution in side-scan sonar and interferometric swath bathymetry resulting in precursor derived geoacoustic maps that will facilitate the safe and expedient follow-on exploration from subsequent manned missions in the next field season. During the course of the precursor AUV missions distinct patches of shallow and deep microbialites were mapped at a spatial resolution of 0.5 m/pixel providing the first detailed bathymetric charts for this alpine lake.

  18. Generation of Vibrationally Excited HCP from a Stable Synthetic Precursor

    NASA Astrophysics Data System (ADS)

    Hull, Alexander W.; Jiang, Jun; Erickson, Trevor J.; Womack, Carrie; Nava, Matthew; Cummins, Christopher; Field, Robert W.

    2015-06-01

    HCP belongs to a class of reactive small molecules with much interest to spectroscopists. It bears certain similarities to HCN, including a strong {A}(bent) - {X}(linear) ultraviolet transition, associated with the HCP-HPC isomerization pathway. HCP has traditionally been generated by the in situ reaction of PH_3 and acetylene. In this talk, we will discuss a recently developed synthetic precursor molecule, 1,1-((triphenylphosphoranylidene)methyl)-9,10-phosphanoanthracene. At temperatures above 200 degrees Celsius, this precursor is thought to release HCP in a vibrationally excited state. We will present preliminary spectra on this system obtained by LIF and chirped pulse millimeter wave spectroscopy.

  19. Differentiation of Mouse Embryonic Stem Cells into Ventral Foregut Precursors.

    PubMed

    Rothová, Michaela; Hölzenspies, Jurriaan J; Livigni, Alessandra; Villegas, Santiago Nahuel; Brickman, Joshua M

    2016-01-01

    Anterior definitive endoderm (ADE), the ventral foregut precursor, is both an important embryonic signaling center and a unique multipotent precursor of liver, pancreas, and other organs. Here, a method is described for the differentiation of mouse embryonic stem cells (mESCs) to definitive endoderm with pronounced anterior character. ADE-containing cultures can be produced in vitro by suspension (embryoid body) culture or in a serum-free adherent monolayer culture. ESC-derived ADE cells are committed to endodermal fates and can undergo further differentiation in vitro towards ventral foregut derivatives. © 2016 by John Wiley & Sons, Inc. PMID:26840225

  20. The dynamo basis of solar cycle precursor schemes

    NASA Astrophysics Data System (ADS)

    Charbonneau, Paul; Barlet, Guillaume

    2011-02-01

    We investigate the dynamo underpinning of solar cycle precursor schemes based on direct or indirect measures of the solar surface magnetic field. We do so for various types of mean-field-like kinematic axisymmetric dynamo models, where amplitude fluctuations are driven by zero-mean stochastic forcing of the dynamo number controlling the strength of the poloidal source term. In all stochastically forced models considered, the surface poloidal magnetic field is found to have precursor value only if it feeds back into the dynamo loop, which suggests that accurate determination of the magnetic flux budget of the solar polar fields may hold the key to dynamo model-based cycle forecasting.

  1. integrated Search for Taiwan Earthquake Precursors (iSTEP)

    NASA Astrophysics Data System (ADS)

    Tsai, T.; Ma, K.; Yen, H.; Chen, K.; Liu, J.; Chen, Y.; Chen, S.

    2003-12-01

    Taiwan is located in an active part of the Circum-Pacific seismic belt. Due to intense collision between the Philippine Sea and Eurasian plates, Taiwan experienced many disastrous earthquakes in the past. The incessant plate collision means that we will inevitably face earthquake hazards in the future. Unfortunately, occurrence of earthquakes still cannot be forecast, much of this is due to lack of predictive capability. The problem of earthquake prediction has been under intensive investigations for nearly forty years in Japan, China, and the U.S. Yet relatively little progress is made thus far. Our frustration over the surprising difficulty of earthquake prediction problem has recently led to a serious debate within the seismological community on predictability of earthquakes. At the heart of the debate is the question on whether there are recognizable precursors of earthquakes? What could be precursors of impending earthquakes? A multitude has been suggested, but it is not clear which, if any, may become reliable. To search possible seismo-precursors and take into account the strength of our research team we decide to undertake this overall project, called ­\\x9DResearch on Seismo-Electromagnetic Precursors of Earthquakes­Ý (or integrated Search for Taiwan Earthquake Precursors (iSTEP)­" during April 2002 ­V March 2006. It consists of five inter-related sub-projects covering the following precursor topics: Sub-project I - A Study of seismological variations; Sub-project II ­V variations of the geomagnetic and gravity fields; Sub-project III - Radar interferometry for detection of surface deformation; Sub-project IV - Ionosospheric variations; and Sub-project V - Statistical studies of earthquake precursors. We then correlate the observed precursors by our sub-projects, as well as by other research organizations, with existing earthquake preparation models to (i) identify any possible, yet reliable precursory phenomena of earthquakes, including seismological, geodetic, geomagnetic, and ionospheric changes, and others, (ii) characterize feasible mechanisms behind the identified precursory phenomena in order to give quantitative physical interpretations and (iii) correlate the identified precursory phenomena with existing or emerging earthquake preparation models in order to lay foundation for future earthquake prediction. In this paper we report the current status and some latest results of the iSTEP.

  2. Transition Zone Structures beneath Hawaii Imaged with SS precursors

    NASA Astrophysics Data System (ADS)

    Yu, C.; van der Hilst, R. D.; Day, E. A.; De Hoop, M. V.

    2014-12-01

    High-resolution seismic images of upper mantle transition zone structures are important for our understanding of the thermal, chemical, and geodynamical evolution of the Earth. In this study, we used precursors of the teleseismic SS phase to image upper mantle transition zones beneath Hawaii. The teleseismic SS phase bounces off the free surface roughly at the middle point between the earthquake epicenter and the recording station, thus providing crucial data coverage of areas where neither natural earthquakes nor passive receivers are available. Its precursors, e.g. S410S and S660S, reflect at deeper interfaces, and therefore arrive before the main SS phase. Differential travel times between the SS phase and its precursors are used for mapping transition zone structures.Due to relatively small amplitudes of SS precursors, a large number of seismograms are usually stacked to enhance their signal to noise ratio (SNR). Traditionally seismograms which share a common bouncepoint are stacked, using a technique known as common middle point stacking (CMP). Random noise is suppressed and the small amplitude precursor signals should become visible. However, if there is strong contamination from other seismic phases in the precursor window, e.g. near receiver reflections such as Ss410s and Ss660s, it will be difficult to identify SS precursors. Here, we applied radon transform filtering to remove multiples both before and after stacking. Application of this technique to our new SS precursor dataset shows that not only is the seismic noise level greatly reduced, but also the resolution of upper mantle structures is significantly improved. With the noise-reduced seismic dataset, we also compared seismic imaging results using both CMP stacking method and generalized radon transform (GRT) method. Except for some subtle and tractable differences, these two methods generally give consistent results. We observe strong and laterally continuous upper mantle reflectors near 410 and 660 km. We also detect local splitting of the "520". Above the transition zone, there are strong reflectors at ~220 km and ~310 km. Thinning of the mantle transition zone is observed to the southeast of the Hawaiian Islands, suggesting a tilted mantle plume in the upper mantle.

  3. L-methionine as an ethylene precursor in Saccharomyces cerevisiae.

    PubMed

    Thomas, K C; Spencer, M

    1977-12-01

    L-Methionine induced production of ethylene by Saccharomyces cerevisiae growing in lactate medium. The production induced by L-methionine was inhibited by pyruvate, and elevated by glucose. Labeled ethylene was produced when L-[U-14C]methionine, but not [U-14C]glucose, was fed to the yeast. The mutant S. cerevisiae G1332 (ade-, met-) did not produce significant amounts of ethylene unless L-methionine was added. Thus L-methionine acts as a precursor of ethylene in S. cerevisiae. The role of glucose appears to be other than as a precursor. PMID:340018

  4. A Brief Up-Date of the Use of Sodium Oxybate for the Treatment of Alcohol Use Disorder.

    PubMed

    Caputo, Fabio; Vignoli, Teo; Tarli, Claudia; Domenicali, Marco; Zoli, Giorgio; Bernardi, Mauro; Addolorato, Giovanni

    2016-01-01

    The treatment of alcohol use disorder (AUD) with sodium oxybate (SMO) or gamma-hydroxybutyric acid (GHB) was introduced in Italy and Austria more than 20 years and 15 years ago, respectively, and it is now widely employed to treat alcohol withdrawal syndrome (AWS) and to maintain alcohol abstinence. These indications derive from its similar structure to the inhibitory neurotransmitter γ-amino-butyric acid (GABA), exerting an ethanol-mimicking effect, because it binds to GABAB receptors. Craving for, and abuse of, SMO remain a controversial issue; even though these unfavorable effects are evident in poly-drug addicted patients and in those with psychiatric diagnosis of borderline personality disorder. In addition, despite cases of severe intoxication and deaths being widely documented when GHB is used as "street drug"; its clinical use remains safe. Thus, the aim of the present review is to examine the role of SMO in the treatment of AUD, its possible implications in reducing alcohol consumption, and cases of abuse, and severe intoxication due to SMO during its clinical use in the treatment of AUD. PMID:26959045

  5. Cognitive, psychomotor, and subjective effects of sodium oxybate and triazolam in healthy volunteers

    PubMed Central

    Carter, Lawrence P.; Griffiths, Roland R.; Mintzer, Miriam Z.

    2009-01-01

    Rationale Illicit gamma-hydroxybutyrate (GHB) has received attention as a “date rape drug” that produces robust amnesia; however, there is little experimental evidence in support of GHB’s amnestic effects. Objectives This study compared the cognitive effects of GHB (sodium oxybate) with those of triazolam in healthy volunteers. Materials and methods Doses of sodium oxybate (1.125, 2.25, and 4.5 g/70 kg), triazolam (0.125, 0.25, and 0.5 mg/70 kg), and placebo were administered to 15 volunteers under repeated measures, counterbalanced, double-blind, double-dummy conditions. The time course and peak physiological, psychomotor, subjective, and cognitive effects were examined. Results Sodium oxybate and triazolam produced similar increases in participant ratings of drug effects. Performance on psychomotor, working memory, and episodic memory tasks was impaired to a greater extent after triazolam than sodium oxybate. Conclusions Together, these data suggest that sodium oxybate produces less psychomotor and cognitive impairment than triazolam at doses that produce equivalent participant-rated subjective effects in healthy volunteers. PMID:19543883

  6. A Brief Up-Date of the Use of Sodium Oxybate for the Treatment of Alcohol Use Disorder

    PubMed Central

    Caputo, Fabio; Vignoli, Teo; Tarli, Claudia; Domenicali, Marco; Zoli, Giorgio; Bernardi, Mauro; Addolorato, Giovanni

    2016-01-01

    The treatment of alcohol use disorder (AUD) with sodium oxybate (SMO) or gamma-hydroxybutyric acid (GHB) was introduced in Italy and Austria more than 20 years and 15 years ago, respectively, and it is now widely employed to treat alcohol withdrawal syndrome (AWS) and to maintain alcohol abstinence. These indications derive from its similar structure to the inhibitory neurotransmitter γ-amino-butyric acid (GABA), exerting an ethanol-mimicking effect, because it binds to GABAB receptors. Craving for, and abuse of, SMO remain a controversial issue; even though these unfavorable effects are evident in poly-drug addicted patients and in those with psychiatric diagnosis of borderline personality disorder. In addition, despite cases of severe intoxication and deaths being widely documented when GHB is used as “street drug”; its clinical use remains safe. Thus, the aim of the present review is to examine the role of SMO in the treatment of AUD, its possible implications in reducing alcohol consumption, and cases of abuse, and severe intoxication due to SMO during its clinical use in the treatment of AUD. PMID:26959045

  7. Focal neurometabolic alterations in mice deficient for succinate semialdehyde dehydrogenase.

    PubMed

    Gibson, K M; Schor, D S M; Gupta, M; Guerand, W S; Senephansiri, H; Burlingame, T G; Bartels, H; Hogema, B M; Bottiglieri, T; Froestl, W; Snead, O C; Grompe, M; Jakobs, C

    2002-04-01

    Metabolite profiling in succinate semialdehyde dehydrogenase (SSADH; Aldh5a1-/-) deficient mice previously revealed elevated gamma-hydroxybutyrate (GHB) and total GABA in urine and total brain and liver extracts. In this study, we extend our metabolic characterization of these mutant mice by documenting elevated GHB and total GABA in homogenates of mutant kidney, pancreas and heart. We quantified beta-alanine (a GABA homolog and putative neurotransmitter) to address its potential role in pathophysiology. We found normal levels of beta-alanine in urine and total homogenates of mutant brain, heart and pancreas, but elevated concentrations in mutant kidney and liver extracts. Amino acid analysis in mutant total brain homogenates revealed no abnormalities except for significantly decreased glutamine, which was normal in mutant liver and kidney extracts. Regional amino acid analysis (frontal cortex, parietal cortex, hippocampus and cerebellum) in mutant mice confirmed glutamine results. Glutamine synthetase protein and mRNA levels in homogenates of mutant mouse brain were normal. We profiled organic acid patterns in mutant brain homogenates to assess brain oxidative metabolism and found normal concentrations of Kreb's cycle intermediates but increased 4,5-dihydroxyhexanoic acid (a postulated derivative of succinic semialdehyde) levels. We conclude that SSADH-deficient mice represent a valid metabolic model of human SSADH deficiency, manifesting focal neurometabolic abnormalities which could provide key insights into pathophysiologic mechanisms. PMID:12067239

  8. College Student Stress: A Predictor of Eating Disorder Precursor Behaviors

    ERIC Educational Resources Information Center

    Shelton, Virginia L.; Valkyrie, Karena T.

    2010-01-01

    Eating disorders are compulsive behaviors that can consume a person's life to the point of becoming life threatening. Previous research found stress associated with eating disorders. College can be a stressful time. If stress predicted precursor behaviors to eating disorders, then counselors would have a better chance to help students sooner. This…

  9. PRIMITIVE ADULT HEMATOPOIETIC STEM CELLS CAN FUNCTION AS OSTEOBLAST PRECURSORS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Osteoblasts are continually recruited from stem cell pools to maintain bone. Although their immediate precursor is a plastic-adherent mesenchymal stem cell able to generate tissues other than bone, increasing evidence suggests the existence of a more primitive cell that can differentiate to both hem...

  10. Low temperature polymeric precursor derived zinc oxide thin films

    NASA Astrophysics Data System (ADS)

    Choppali, Uma

    Zinc oxide (ZnO) is a versatile environmentally benign II-VI direct wide band gap semiconductor with several technologically plausible applications such as transparent conducting oxide in flat panel and flexible displays. Hence, ZnO thin films have to be processed below the glass transition temperatures of polymeric substrates used in flexible displays. ZnO thin films were synthesized via aqueous polymeric precursor process by different metallic salt routes using ethylene glycol, glycerol, citric acid, and ethylene diamine tetraacetic acid (EDTA) as chelating agents. ZnO thin films, derived from ethylene glycol based polymeric precursor, exhibit flower-like morphology whereas thin films derived of other precursors illustrate crack free nanocrystalline films. ZnO thin films on sapphire substrates show an increase in preferential orientation along the (002) plane with increase in annealing temperature. The polymeric precursors have also been used in fabricating maskless patterned ZnO thin films in a single step using the commercial Maskless Mesoscale Materials Deposition (M3D(TM)) system.

  11. TRIHALOMETHANE PRECURSOR REMOVAL BY THE MAGNESIUM CARBONATE PROCESS

    EPA Science Inventory

    A project was conducted to determine and improve the ability of the magnesium carbonate process to remove trihalomethane (THM) precursors in treated drinking water. The project was conducted at a drinking water treatment plant in Melbourne, FL, which had been developed and instal...

  12. Synthesis and use of a trifluoromethylated azomethine ylide precursor.

    PubMed

    Tran, Gal; Meier, Robin; Harris, Lawrence; Browne, Duncan L; Ley, Steven V

    2012-12-21

    The presence of fluorous substituents can impart a dramatic effect on the efficacy of molecules used for a range of applications in society. Here, we describe the preparation and use of a new trifluoromethylated azomethine ylide precursor, which leads to a series of fluorinated pyrrolidine, 3-pyrroline, and pyrrole building blocks. PMID:23176732

  13. NASA's Accident Precursor Analysis Process and the International Space Station

    NASA Technical Reports Server (NTRS)

    Groen, Frank; Lutomski, Michael

    2010-01-01

    This viewgraph presentation reviews the implementation of Accident Precursor Analysis (APA), as well as the evaluation of In-Flight Investigations (IFI) and Problem Reporting and Corrective Action (PRACA) data for the identification of unrecognized accident potentials on the International Space Station.

  14. Glutamine: precursor or nitrogen donor for citrulline synthesis?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Glutamine (Gln) is considered the main precursor for citrulline (Cit) synthesis, but no attempts have been made to differentiate the contribution of Gln carbon (Gln-C) skeleton vs. the nonspecific contribution through NH3 and CO2. To study the contribution of dietary Gln-N to the synthesis of Cit, t...

  15. Precursors for ornithine and citrulline synthesis in neonatal pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Citrulline (CIT) is an amino acid synthesized by gut and utilized for the synthesis of the conditionally essential amino acid arginine (ARG). In turn, the immediate precursor for CIT synthesis, ornithine (ORN), can originate from proline (PRO) and glutamine (GLN) via ornithine aminotransferase (OAT,...

  16. Glutamine: Precursor or nitrogen donor for citrulline synthesis?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although glutamine is considered the main precursor for citrulline synthesis, the current literature does not differentiate between the contribution of glutamine carbon skeleton, versus nonspecific nitrogen (i.e., ammonia) and carbon derived from glutamine oxidation. To elucidate the role of glutami...

  17. Developmental Dyslexia: Early Precursors, Neurobehavioral Markers, and Biological Substrates

    ERIC Educational Resources Information Center

    Benasich, April A., Ed.; Fitch, R. Holly, Ed.

    2012-01-01

    Understanding the precursors and early indicators of dyslexia is key to early identification and effective intervention. Now there's a single research volume that brings together the very latest knowledge on the earliest stages of dyslexia and the diverse genetic, neurobiological, and cognitive factors that may contribute to it. Based on findings…

  18. RIVERBANK FILTRATION: FATE OF DBP PRECURSORS AND SELECTED MICROORGANISMS

    EPA Science Inventory

    The fate of disinfection by-product (DBP) precursors and selected microorganisms during riverbank filtration (RBF) was monitored at three different mid-Western drinking water utilities. At all three sites, filtration (RBF) was monitored at three different mid-Western drinking wa...

  19. Technical Note: Methionine, a precursor of methane in living plants

    NASA Astrophysics Data System (ADS)

    Lenhart, K.; Althoff, F.; Greule, M.; Keppler, F.

    2015-03-01

    When terrestrial plants were identified as producers of the greenhouse gas methane, much discussion and debate ensued not only about their contribution to the global methane budget but also with regard to the validity of the observation itself. Although the phenomenon has now become more accepted for both living and dead plants, the mechanism of methane formation in living plants remains to be elucidated and its precursor compounds to be identified. We made use of stable isotope techniques to verify the in vivo formation of methane, and, in order to identify the carbon precursor, 13C positionally labeled organic compounds were employed. Here we show that the amino acid L-methionine acts as a methane precursor in living plants. Employing 13C-labeled methionine clearly identified the sulfur-bound methyl group of methionine as a carbon precursor of methane released from lavender (Lavandula angustifolia). Furthermore, when lavender plants were stressed physically, methane release rates and the stable carbon isotope values of the emitted methane greatly increased. Our results provide additional support that plants possess a mechanism for methane production and suggest that methionine might play an important role in the formation of methane in living plants, particularly under stress conditions.

  20. Technical note: Methionine, a precursor of methane in living plants

    NASA Astrophysics Data System (ADS)

    Lenhart, K.; Althoff, F.; Greule, M.; Keppler, F.

    2014-11-01

    When terrestrial plants were identified as producers of the greenhouse gas methane, much discussion and debate ensued, not only about their contribution to the global methane budget, but also with regard to the validity of the observation itself. Although the phenomenon has now become more accepted for both living and dead plants, the mechanism of methane formation in living plants remains to be elucidated and its precursor compounds identified. We made use of stable isotope techniques to verify in vivo formation of methane and, in order to identify the carbon precursor, 13C-positionally labelled organic compounds were employed. Here we show that the amino acid L-methionine acts as a methane precursor in living plants. Employing 13C-labelled methionine clearly identified the sulphur-bound methyl group of methionine as a carbon precursor of methane released from lavender (Lavandula angustifolia). Furthermore, when lavender plants were stressed physically, methane release rates and the stable carbon isotope values of the emitted methane greatly increased. Our results provide additional support that plants possess a mechanism for methane production and suggest that methionine might play an important role in the formation of methane in living plants, particularly under stress conditions.

  1. ASSESSMENT OF NATIONAL AND REGIONAL ACID DEPOSITION PRECURSOR EMISSION TRENDS

    EPA Science Inventory

    The report gives results of an analysis of national and regional acid deposition precursor emission trends, involving SOx, NOx, and VOCs. While the focus is on emissions during 1980-1985, comparisons are made (for perspective) with emission trends for 1940-1980. Study methods int...

  2. Precursors to Numeracy in Kindergartners with Specific Language Impairment

    ERIC Educational Resources Information Center

    Kleemans, Tijs; Segers, Eliane; Verhoeven, Ludo

    2011-01-01

    The present study investigated to what extent children with specific language impairment (SLI) differ in their early numeracy skills, when compared to normal language achieving (NLA) children. It was also explored which precursors were related to the early numeracy skills in both groups. Sixty-one children with SLI (6; 1 years) and 111 NLA

  3. 21 CFR 1308.47 - Control of immediate precursors.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 9 2013-04-01 2013-04-01 false Control of immediate precursors. 1308.47 Section 1308.47 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE SCHEDULES OF CONTROLLED... § 1308.41 or subsections 201 (a) and (b) of the Act (21 U.S.C. 811(a) and (b)), issue and publish in...

  4. 21 CFR 1308.47 - Control of immediate precursors.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Control of immediate precursors. 1308.47 Section 1308.47 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE SCHEDULES OF CONTROLLED... § 1308.41 or subsections 201 (a) and (b) of the Act (21 U.S.C. 811(a) and (b)), issue and publish in...

  5. 21 CFR 1308.47 - Control of immediate precursors.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 9 2012-04-01 2012-04-01 false Control of immediate precursors. 1308.47 Section 1308.47 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE SCHEDULES OF CONTROLLED... § 1308.41 or subsections 201 (a) and (b) of the Act (21 U.S.C. 811(a) and (b)), issue and publish in...

  6. 21 CFR 1308.47 - Control of immediate precursors.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 9 2011-04-01 2011-04-01 false Control of immediate precursors. 1308.47 Section 1308.47 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE SCHEDULES OF CONTROLLED... § 1308.41 or subsections 201 (a) and (b) of the Act (21 U.S.C. 811(a) and (b)), issue and publish in...

  7. Precursors to Numeracy in Kindergartners with Specific Language Impairment

    ERIC Educational Resources Information Center

    Kleemans, Tijs; Segers, Eliane; Verhoeven, Ludo

    2011-01-01

    The present study investigated to what extent children with specific language impairment (SLI) differ in their early numeracy skills, when compared to normal language achieving (NLA) children. It was also explored which precursors were related to the early numeracy skills in both groups. Sixty-one children with SLI (6; 1 years) and 111 NLA…

  8. Process for producing ceramic nitrides anc carbonitrides and their precursors

    DOEpatents

    Brown, G.M.; Maya, L.

    1987-02-25

    A process for preparing ceramic nitrides and carbon nitrides in the form of very pure, fine particulate powder. Appropriate precursors is prepared by reaching a transition metal alkylamide with ammonia to produce a mixture of metal amide and metal imide in the form of an easily pyrolyzable precipitate.

  9. Intrathymic maturation of murine T lymphocytes from CD8+ precursors.

    PubMed Central

    Guidos, C J; Weissman, I L; Adkins, B

    1989-01-01

    The CD4-8- thymocyte subset contains immature precursors for phenotypically and functionally mature CD4+8- and CD4-8+ thymocytes and peripheral T cells, as well as nonmature CD4+8+ thymocytes, most of which die in situ. The intrathymic death of most thymocytes is probably related to selective influences that ensure that only those precursors bearing self-major histocompatibility complex (MHC)-restricted and self-tolerant T-cell antigen receptors (TCR) survive to complete the maturation process. Interactions between surface molecules on thymocytes (TCR, CD4, and CD8) and thymic stromal cells (MHC proteins) are critical to repertoire selection. To understand this process, the lineage relationships among immature, nonmature, and mature thymocytes must be defined. We have examined directly the precursor-progeny relationships among CD4+8-, CD4-8+, and CD4+8+ murine thymocyte subsets by assessing their short-term (less than 5 days) developmental potentials following intrathymic injection into Thy-1 congenic, unirradiated host mice. Our results identify TCR-/lo CD4-8+ and TCRlo CD4+8+ blast cells as sequential intermediates in the development of mature TCRhi CD4+8- and TCRhi CD4-8+ thymocytes from CD4-8- precursors, thus defining at least one intrathymic maturation pathway for T lymphocytes. PMID:2508090

  10. Manganite perovskite ceramics, their precursors and methods for forming

    SciTech Connect

    Payne, David Alan; Clothier, Brent Allen

    2015-03-10

    Disclosed are a variety of ceramics having the formula Ln.sub.1-xM.sub.xMnO.sub.3, where 0.Itoreq.x.Itoreq.1 and where Ln is La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu or Y; M is Ca, Sr, Ba, Cd, or Pb; manganite precursors for preparing the ceramics; a method for preparing the precursors; and a method for transforming the precursors into uniform, defect-free ceramics having magnetoresistance properties. The manganite precursors contain a sol and are derived from the metal alkoxides: Ln(OR).sub.3, M(OR).sub.2 and Mn(OR).sub.2, where R is C.sub.2 to C.sub.6 alkyl or C.sub.3 to C.sub.9 alkoxyalkyl, or C.sub.6 to C.sub.9 aryl. The preferred ceramics are films prepared by a spin coating method and are particularly suited for incorporation into a device such as an integrated circuit device.

  11. Developmental Dyslexia: Early Precursors, Neurobehavioral Markers, and Biological Substrates

    ERIC Educational Resources Information Center

    Benasich, April A., Ed.; Fitch, R. Holly, Ed.

    2012-01-01

    Understanding the precursors and early indicators of dyslexia is key to early identification and effective intervention. Now there's a single research volume that brings together the very latest knowledge on the earliest stages of dyslexia and the diverse genetic, neurobiological, and cognitive factors that may contribute to it. Based on findings

  12. Neuronal differentiation from postmitotic precursors in the ciliary ganglion.

    PubMed

    Lee, Vivian M; Sechrist, John W; Bronner-Fraser, Marianne; Nishi, Rae

    2002-12-15

    In the chick ciliary ganglion, neuronal number is kept constant between St. 29 and St. 34 (E6-E8) despite a large amount of cell death. Here, we characterize the source of neurogenic cells in the ganglion as undifferentiated neural crest-derived cells. At St. 29, neurons and nonneuronal cells in the ciliary ganglion expressed the neural crest markers HNK-1 and p75(NTR). Over 50% of the cells were neurons at St. 29; of the nonneuronal cells, a small population expressed glial markers, whereas the majority was undifferentiated. When placed in culture, nonneuronal cells acquired immunoreactivity for HuD, suggesting that they had commenced neuronal differentiation. The newly differentiated neurons arose from precursors that did not incorporate bromodeoxyuridine. To test whether these precursors could undergo neural differentiation in vivo, purified nonneuronal cells from St. 29 quail ganglia were transplanted into chick embryos at St. 9-14. Subsequently, quail cells expressing neuronal markers were found in the chick ciliary ganglion. The existence of this precursor pool was transient because nonneuronal cells isolated from St. 38 ganglia failed to form neurons. Since all ciliary ganglion neurons are born prior to St. 29, these results demonstrate that there are postmitotic neural crest-derived precursors in the developing ciliary ganglion that can differentiate into neurons in the appropriate environment. PMID:12482718

  13. Methionine as a Precursor of Ethylene—Commentary

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lieberman et al. showed in a 1966 publication of Plant Physiology that methionine is a precursor of ethylene. It was the first paper that showed ethylene carbons are derived from carbons 3 and 4 of methionine. This paper catalyzed remarkable interest among plant biologists to elucidate the biosynth...

  14. RESPONSE OF INORGANIC PM TO PRECURSOR CONCENTRATIONS (R824793)

    EPA Science Inventory

    An inorganic aerosol equilibrium model is used to investigate the response of inorganic particulate matter (PM) concentrations with respect to the precursor concentrations of sulfuric acid, ammonia, and nitric acid over a range of temperatures and relative humidities. Diagrams...

  15. Environment Conscious, Biomorphic Ceramics from Pine and Jelutong Wood Precursors

    NASA Technical Reports Server (NTRS)

    Singh, Mrityunjay; Yee, Bo-Moon; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Environment conscious, biomorphic ceramics have been fabricated from pine and jelutong wood precursors. A carbonaceous preform is produced through wood pyrolysis and subsequent infiltration with oxides (ZrO2 sols) and liquid silicon to form ceramics. These biomorphic ceramics show a wide variety of microstructures, densities, and hardness behavior that are determined by the type of wood and infiltrants selected.

  16. Crystallographic Snapshot of Glycosylasparaginase Precursor Poised for Autoprocessing

    SciTech Connect

    Wang, Y.; Guo, H

    2010-01-01

    Glycosylasparaginase belongs to a family of N-terminal nucleophile hydrolases that autoproteolytically generate their mature enzymes from single-chain protein precursors. Previously, based on a precursor structure paused at pre-autoproteolysis stage by a reversible inhibitor (glycine), we proposed a mechanism of intramolecular autoproteolysis. A key structural feature, a highly strained conformation at the scissile peptide bond, had been identified and was hypothesized to be critical for driving autoproteolysis through an N-O acyl shift. To examine this 'twist-and-break' hypothesis, we report here a 1.9-{angstrom}-resolution structure of an autoproteolysis-active precursor (a T152C mutant) that is free of inhibitor or ligand and is poised to undergo autoproteolysis. The current crystallographic study has provided direct evidence for the natural conformation of the glycosylasparaginase autocatalytic site without influence from any inhibitor or ligand. This finding has confirmed our previous proposal that conformational strain is an intrinsic feature of an active precursor.

  17. Process for producing ceramic nitrides and carbonitrides and their precursors

    DOEpatents

    Brown, Gilbert M.; Maya, Leon

    1988-01-01

    A process for preparing ceramic nitrides and carbonitrides in the form of very pure, fine particulate powder. Appropriate precursor is prepared by reacting a transition metal alkylamide with ammonia to produce a mixture of metal amide and metal imide in the form of an easily pyrolyzable precipitate.

  18. PILOT SCALE EVALUATION OF PHOTOLYTIC OZONATION FOR TRIHALOMETHANE PRECURSOR REMOVAL

    EPA Science Inventory

    The use of ozone combined with ultraviolet radiation has been studied at the pilot-scale for removing trihalomethane (THM) precursors from potable water. The effects of variations in ozone dose rate, UV intensity and other parameters were first studied using a synthetic feedwater...

  19. Boron nitride ceramics from molecular precursors: synthesis, properties and applications.

    PubMed

    Bernard, Samuel; Salameh, Chrystelle; Miele, Philippe

    2016-01-21

    Hexagonal boron nitride (h-BN) attracts considerable interest because its structure is similar to that of carbon graphite while it displays different properties which are of interest for environmental and green technologies. The polar nature of the B-N bond in sp(2)-bonded BN makes it a wide band gap insulator with different chemistry on its surface and particular physical and chemical properties such as a high thermal conductivity, a high temperature stability, a high resistance to corrosion and oxidation and a strong UV emission. It is chemically inert and nontoxic and has good environmental compatibility. h-BN also has enhanced physisorption properties due to the dipolar fields near its surface. Such properties are closely dependent on the processing method. Bottom-up approaches consist of transforming molecular precursors into non-oxide ceramics with retention of the structural units inherent to the precursor molecule. The purpose of the present review is to give an up-to-date overview on the most recent achievements in the preparation of h-BN from borazine-based molecular single-source precursors including borazine and 2,4,6-trichloroborazine through both vapor phase syntheses and methods in the liquid/solid state involving polymeric intermediates, called the Polymer-Derived Ceramics (PDCs) route. In particular, the effect of the chemistry, composition and architecture of the borazine-based precursors and derived polymers on the shaping ability as well as the properties of h-BN is particularly highlighted. PMID:26646607

  20. Particulate and THM precursor removal with ferric chloride

    SciTech Connect

    Childress, A.E.; Vrijenhoek, E.M.; Elimelech, M.; Tanaka, T.S.; Beuhler, M.D.

    1999-11-01

    Pilot-scale experiments were performed to investigate the effectiveness of enhanced coagulation in removing particles and trihalomethane (THM) precursors from two surface source waters: California State Project water and Colorado River water. The removal of suspended particles and natural organic matter at various ferric chloride doses and coagulation pHs was assessed through source water and filter effluent measurements of turbidity, particle count. UV{sub 254}, TOC, and THM formation potential. Overall, it was found that optimal removal of particles and THM precursors by enhanced coagulation with ferric chloride is obtained at high coagulant doses and low pH conditions. Generally, turbidity removal is more efficient and head loss is more moderate at ambient pH compared with pH 5.5. Additionally, filter effluent particle counts were found to be consistent with residual turbidity data. The removal of THM precursors by enhanced coagulation is significantly enhanced at pH 5.5 compared with ambient pH. The reduction in THM formation potential is consistent with the trends observed for the THM precursor removal data. Furthermore, specific UV absorbance was used to estimate the proportion of humic substances in the raw waters. Enhanced coagulation was found to be less effective for the source water with the lower specific UV absorbance.

  1. Urinary excretion of morphine and biosynthetic precursors in mice.

    PubMed

    Grobe, Nadja; Lamshft, Marc; Orth, Robert G; Drger, Birgit; Kutchan, Toni M; Zenk, Meinhart H; Spiteller, Michael

    2010-05-01

    It has been firmly established that humans excrete a small but steady amount of the isoquinoline alkaloid morphine in their urine. It is unclear whether it is of dietary or endogenous origin. There is no doubt that a simple isoquinoline alkaloid, tetrahydropapaveroline (THP), is found in human and rodent brain as well as in human urine. This suggests a potential biogenetic relationship between both alkaloids. Unlabeled THP or [1,3,4-D(3)]-THP was injected intraperitoneally into mice and the urine was analyzed. This potential precursor was extensively metabolized (96%). Among the metabolites found was the phenol-coupled product salutaridine, the known morphine precursor in the opium poppy plant. Synthetic [7D]-salutaridinol, the biosynthetic reduction product of salutaridine, injected intraperitoneally into live animals led to the formation of [7D]-thebaine, which was excreted in urine. [N-CD(3)]-thebaine was also administered and yielded [N-CD(3)]-morphine and the congeners [N-CD(3)]-codeine and [N-CD(3)]-oripavine in urine. These results show for the first time that live animals have the biosynthetic capability to convert a normal constituent of rodents, THP, to morphine. Morphine and its precursors are normally not found in tissues or organs, presumably due to metabolic breakdown. Hence, only that portion of the isoquinoline alkaloids excreted in urine unmetabolized can be detected. Analysis of urine by high resolution-mass spectrometry proved to be a powerful method for tracking endogenous morphine and its biosynthetic precursors. PMID:20421505

  2. Inflammatory arthritis increases mouse osteoclast precursors with myeloid suppressor function.

    PubMed

    Charles, Julia F; Hsu, Lih-Yun; Niemi, Erene C; Weiss, Arthur; Aliprantis, Antonios O; Nakamura, Mary C

    2012-12-01

    Increased osteoclastic bone resorption leads to periarticular erosions and systemic osteoporosis in RA patients. Although a great deal is known about how osteoclasts differentiate from precursors and resorb bone, the identity of an osteoclast precursor (OCP) population in vivo and its regulatory role in RA remains elusive. Here, we report the identification of a CD11b(-/lo)Ly6C(hi) BM population with OCP activity in vitro and in vivo. These cells, which can be distinguished from previously characterized precursors in the myeloid lineage, display features of both M1 and M2 monocytes and expand in inflammatory arthritis models. Surprisingly, in one mouse model of RA (adoptive transfer of SKG arthritis), cotransfer of OCP with SKG CD4+ T cells diminished inflammatory arthritis. Similar to monocytic myeloid-derived suppressor cells (M-MDSCs), OCPs suppressed CD4+ and CD8+ T cell proliferation in vitro through the production of NO. This study identifies a BM myeloid precursor population with osteoclastic and T cell-suppressive activity that is expanded in inflammatory arthritis. Therapeutic strategies that prevent the development of OCPs into mature bone-resorbing cells could simultaneously prevent bone resorption and generate an antiinflammatory milieu in the RA joint. PMID:23114597

  3. AIMSTAR: Antimatter initiated microfusion for pre-cursor interstellar missions

    NASA Astrophysics Data System (ADS)

    Gaidos, G.; Lewis, R. A.; Meyer, K.; Schmidt, T.; Smith, G. A.

    1999-05-01

    We address the challenge of delivering a scientific payload to 10,000 A.U. in 50 years. This mission may be viewed as a pre-cursor to later missions to Alpha Centauri and beyond. We consider a small, aneutronic nuclear fusion engine sparked by clouds of antiprotons, and describe the principle and operation of the engine and mission parameters.

  4. AIMStar: Antimatter initiated microfusion for pre-cursor interstellar missions

    NASA Astrophysics Data System (ADS)

    Gaidos, Gerard; Lewis, Raymond A.; Meyer, Kirby; Schmidt, Thomas; Smith, Gerald A.

    1999-01-01

    We address the challenge of delivering a scientific payload to 10,000 A.U. in 50 years. This mission may be viewed as a pre-cursor to later missions to Alpha Centauri and beyond. We consider a small, nuclear fusion engine sparked by clouds of antiprotons, and describe the principle and operation of the engine and mission parameters.

  5. Solution precursor plasma deposition of nanostructured ZnO coatings

    SciTech Connect

    Tummala, Raghavender; Guduru, Ramesh K.; Mohanty, Pravansu S.

    2011-08-15

    Highlights: {yields} The solution precursor route employed is an inexpensive process with capability to produce large scale coatings at fast rates on mass scale production. {yields} It is highly capable of developing tailorable nanostructures. {yields} This technique can be employed to spray the coatings on any kind of substrates including polymers. {yields} The ZnO coatings developed via solution precursor plasma spray process have good electrical conductivity and reflectivity properties in spite of possessing large amount of particulate boundaries, porosity and nanostructured grains. -- Abstract: Zinc oxide (ZnO) is a wide band gap semiconducting material that has various applications including optical, electronic, biomedical and corrosion protection. It is usually synthesized via processing routes, such as vapor deposition techniques, sol-gel, spray pyrolysis and thermal spray of pre-synthesized ZnO powders. Cheaper and faster synthesis techniques are of technological importance due to increased demand in alternative energy applications. Here, we report synthesis of nanostructured ZnO coatings directly from a solution precursor in a single step using plasma spray technique. Nanostructured ZnO coatings were deposited from the solution precursor prepared using zinc acetate and water/isopropanol. An axial liquid atomizer was employed in a DC plasma spray torch to create fine droplets of precursor for faster thermal treatment in the plasma plume to form ZnO. Microstructures of coatings revealed ultrafine particulate agglomerates. X-ray diffraction confirmed polycrystalline nature and hexagonal Wurtzite crystal structure of the coatings. Transmission electron microscopy studies showed fine grains in the range of 10-40 nm. Observed optical transmittance ({approx}65-80%) and reflectivity ({approx}65-70%) in the visible spectrum, and electrical resistivity (48.5-50.1 m{Omega} cm) of ZnO coatings are attributed to ultrafine particulate morphology of the coatings.

  6. Whole-cell fungal transformation of precursors into dyes

    PubMed Central

    2010-01-01

    Background Chemical methods of producing dyes involve extreme temperatures and unsafe toxic compounds. Application of oxidizing enzymes obtained from fungal species, for example laccase, is an alternative to chemical synthesis of dyes. Laccase can be replaced by fungal biomass acting as a whole-cell biocatalyst with properties comparable to the isolated form of the enzyme. The application of the whole-cell system simplifies the transformation process and reduces the time required for its completion. In the present work, four fungal strains with a well-known ability to produce laccase were tested for oxidation of 17 phenolic and non-phenolic precursors into stable and non-toxic dyes. Results An agar-plate screening test of the organic precursors was carried out using four fungal strains: Trametes versicolor, Fomes fomentarius, Abortiporus biennis, and Cerrena unicolor. Out of 17 precursors, nine were transformed into coloured substances in the presence of actively growing fungal mycelium. The immobilized fungal biomass catalyzed the transformation of 1 mM benzene and naphthalene derivatives in liquid cultures yielding stable and non-toxic products with good dyeing properties. The type of fungal strain had a large influence on the absorbance of the coloured products obtained after 48-hour transformation of the selected precursors, and the most effective was Fomes fomentarius (FF25). Whole-cell transformation of AHBS (3-amino-4-hydroxybenzenesulfonic acid) into a phenoxazinone dye was carried out in four different systems: in aqueous media comprising low amounts of carbon and nitrogen source, in buffer, and in distilled water. Conclusions This study demonstrated the ability of four fungal strains belonging to the ecological type of white rot fungi to transform precursors into dyes. This paper highlights the potential of fungal biomass for replacing isolated enzymes as a cheaper industrial-grade biocatalyst for the synthesis of dyes and other commercially important products. The use of immobilized fungal biomass limits free migration of cells and facilitates their reuse in a continuous system for precursor transformation. PMID:20598166

  7. Making Single-Source Precursors of Ternary Semiconductors

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius; Banger, Kulbindre K.

    2007-01-01

    A synthesis route has been developed for the commercial manufacture of single- source precursors of chalcopyrite semiconductor absorber layers of thin-film solar photovoltaic cells. A closely related class of single-source precursors of these semiconductors, and their synthesis routes, were reported in "Improved Single-Source Precursors for Solar-Cell Absorbers" (LEW-17445-1), NASA Tech Briefs, Vol. 31, No. 6 (June 2007), page 56. The present synthesis route is better suited to commercialization because it is simpler and involves the use of commercially available agents, yet offers the flexibility needed for synthesis of a variety of precursors. A single-source precursor of the type of interest here is denoted by the general formula L2M'(mu-ER)2M(ER)2, where L signifies a Lewis base; M signifies Al, In, or Ga; M' signifies Ag or Cu; R signifies an alkyl, aryl, silyl, or perfluorocarbon group; E signifies O, S, Se, or Te; and mu signifies a bridging ligand. This compound can be synthesized in a "one-pot" procedure from ingredients that are readily available from almost any chemical supplier. In a demonstration, the following synthesis was performed: Under anaerobic conditions, InCl3 was reacted with sodium ethanethiolate in methanol in a 1:4 molar ratio to afford the ionic stable intermediate compound Na+[In(SEt)4]- (where Et signifies ethyl group). After approximately 15 minutes, a heterogeneous solution of CuCl and the Lewis base PPh3 (where Ph signifies phenyl) in a 1:2 ratio in a mixture of CH3CN and CH2Cl2 was added directly to the freshly prepared Na+[In(SEt)4]-. After 24 hours, the reaction was essentially complete. The methanolic solution was concentrated, then the product was extracted with CH2Cl2, then the product was washed with dry ether and pentane. The product in its final form was a creamy white solid. Spectroscopic and elemental analysis confirmed that the product was (PPh3)2Cu(mu-SEt)2In(mu-SEt)2, which is known to be a precursor of the ternary semiconductor CuInS2.

  8. CARBONACEOUS MATTER PRECURSORS AND METAMORPHIC CONDITIONS IN THERMALLY PROCESSED CHONDRITES

    NASA Astrophysics Data System (ADS)

    Quirico, E.; Montagnac, G.; Rouzaud, J.; Bonal, L.; Bourot-Denise, M.; Duber, S.; Reynard, B.

    2009-12-01

    Unravelling the origin of carbonaceous matter in pristine chondrites requires the understanding of the effect of post-accretion processes. In chondrites of petrologic type 3, thermal metamorphism modified to various extents the composition and structure of carbonaceous matter. Interestingly, this process controls the degree of structural order of carbonaceous matter, and clues on the thermal history of the parent body may be recovered from the physico-chemical study of carbonaceous matter. Following this framework, geothermometers based on Raman spectrometry of carbonaceous matter and covering a wide range of temperatures (100-650 °C) have been developed over recent years, both on terrestrial rocks and chondrites. While Raman data have been largely interpreted in terms of temperature, they are also the fingerprint of certain metamorphic conditions, especially in the low temperature range relevant to poorly ordered carbonaceous matter. This study investigates the Raman spectra of two series of chondritic carbonaceous matter and coal samples formed from different precursors and under different metamorphic conditions. The Raman spectra of Polyaromatic Carbonaceous Matter (PCM) from 42 chondrites and 27 coal samples, measured with visible (514 nm) and ultra-violet (244 nm) excitation wavelengths, are analyzed. The Raman spectra of low rank coals and chondrites of petrologic types 1 and 2, which contain the more disordered PCM, reflect the distinct carbon structures of their precursors. The 514 nm Raman spectra of high rank coals and chondrites of petrologic type 3 exhibit continuous and systematic spectral differences reflecting different carbon structures present during the metamorphism event. They result from differences in the chemical structures of the precursors concerning for instance the reticulation of polyaromatic units or an abundance of ether functional groups, or possibly from a lack of carbonization processes to efficiently expel oxygen heteroatoms, due to weak lithostatic pressure and confinement. These results suggest that the use of lowtemperature carbon thermometers should be restricted to a given geological context. At the same time, the sensitivity of Raman spectra to precursors and certain metamorphic conditions could be used to obtain information other than temperature. The analysis also provides evidence of the accretion of relatively homogeneous PCM precursors among ordinary CO and CV carbonaceous chondrite parent bodies, given that the 514nm Raman spectra of PCM efficiently trace the metamorphism grades. Looking closer, however, the 514 nm Raman data are more scattered in chondrites than in coals and the maturity tracers are less sensitive and miscorrelate with the atomic H/C ratio, suggesting slight compositional and structural differences among the PCM precursors accreted.

  9. Atomic scale simulation of carbon nanotube nucleation from hydrocarbon precursors

    PubMed Central

    Khalilov, Umedjon; Bogaerts, Annemie; Neyts, Erik C.

    2015-01-01

    Atomic scale simulations of the nucleation and growth of carbon nanotubes is essential for understanding their growth mechanism. In spite of over twenty years of simulation efforts in this area, limited progress has so far been made on addressing the role of the hydrocarbon growth precursor. Here we report on atomic scale simulations of cap nucleation of single-walled carbon nanotubes from hydrocarbon precursors. The presented mechanism emphasizes the important role of hydrogen in the nucleation process, and is discussed in relation to previously presented mechanisms. In particular, the role of hydrogen in the appearance of unstable carbon structures during in situ experimental observations as well as the initial stage of multi-walled carbon nanotube growth is discussed. The results are in good agreement with available experimental and quantum-mechanical results, and provide a basic understanding of the incubation and nucleation stages of hydrocarbon-based CNT growth at the atomic level. PMID:26691537

  10. Fission-based electric propulsion for interstellar precursor missions

    NASA Astrophysics Data System (ADS)

    Lipinski, Ronald J.; Lenard, Roger X.; Wright, Steven A.; Houts, Michael G.; Patton, Bruce; Poston, David

    2000-01-01

    This paper reviews the technology options for a fission-based electric propulsion system for interstellar precursor missions. To achieve a total ΔV of more than 100 km/s in less than a decade of thrusting with an electric propulsion system of 10,000 s Isp requires a specific mass for the power system of less than 35 kg/k We. Three possible configurations are described: (1) a UZrH-fueled, NaK-cooled reactor with a steam Rankine conversion system, (2) a UN-fueled gas-cooled reactor with a recuperated Brayton conversion system, and (3) a UN-fueled heatpipe-cooled reactor with a recuperated Brayton conversion system. All three of these systems have the potential to meet the specific mass requirements for interstellar precursor missions in the near term. Advanced versions of a fission-based electric propulsion system might travel as much as several light years in 200 years. .

  11. Can precursors improve the transmission of energy at optical frequencies?

    PubMed

    Lukofsky, David; Bessette, Jonathan; Jeong, Heejeong; Garmire, Elsa; Osterberg, Ulf

    2009-05-01

    The recent interest in precursors has been fuelled by the possibility of using them for the efficient transmission of information through absorbing media at radio or optical frequencies. Here we demonstrate that the low attenuation experienced by the Brillouin precursor is attributed to the inherently low absorption of dispersive media near DC, a characteristic already exploited with communications systems using the extremely low frequency (ELF) band. Pulses, regardless of their temporal width and carrier frequency, always obey Beer's law as long as they propagate in the linear time invariant regime. We conclude with an FDTD simulation of the Maxwell-Bloch equations that shows how optical coherent bleaching effects, which take place in the linear time variant regime of the Lorentz oscillator model, can cause sustained deviations from Beer's law over relatively long distances of water. PMID:19639054

  12. Can precursors improve the transmission of energy at optical frequencies?

    PubMed Central

    Lukofsky, David; Bessette, Jonathan; Jeong, Heejeong; Garmire, Elsa; Österberg, Ulf

    2009-01-01

    The recent interest in precursors has been fuelled by the possibility of using them for the efficient transmission of information through absorbing media at radio or optical frequencies. Here we demonstrate that the low attenuation experienced by the Brillouin precursor is attributed to the inherently low absorption of dispersive media near DC, a characteristic already exploited with communications systems using the extremely low frequency (ELF) band. Pulses, regardless of their temporal width and carrier frequency, always obey Beer's law as long as they propagate in the linear time invariant regime. We conclude with an FDTD simulation of the Maxwell–Bloch equations that shows how optical coherent bleaching effects, which take place in the linear time variant regime of the Lorentz oscillator model, can cause sustained deviations from Beer's law over relatively long distances of water. PMID:19639054

  13. Fission-Based Electric Propulsion for Interstellar Precursor Missions

    SciTech Connect

    HOUTS,MICHAEL G.; LENARD,ROGER X.; LIPINSKI,RONALD J.; PATTON,BRUCE; POSTON,DAVID; WRIGHT,STEVEN A.

    1999-11-03

    This paper reviews the technology options for a fission-based electric propulsion system for interstellar precursor missions. To achieve a total {Delta}V of more than 100 km/s in less than a decade of thrusting with an electric propulsion system of 10,000s Isp requires a specific mass for the power system of less than 35 kg/kWe. Three possible configurations are described: (1) a UZrH-fueled,NaK-cooled reactor with a steam Rankine conversion system,(2) a UN-fueled gas-cooled reactor with a recuperated Brayton conversion system, and (3) a UN-fueled heat pipe-cooled reactor with a recuperated Brayton conversion system. All three of these systems have the potential to meet the specific mass requirements for interstellar precursor missions in the near term. Advanced versions of a fission-based electric propulsion system might travel as much as several light years in 200 years.

  14. The role of catalyst precursor anions in coal gasification

    SciTech Connect

    Abotsi, G.M.K.

    1992-01-01

    The aims of the proposed project are to enrich our understanding of the roles of various aqueous soluble catalyst precursor anions on the surface electrical properties of coal and to ascertain the influence of the surface charge on the adsorption, dispersion, and activities of calcium and potassium. These goals will be achieved by impregnating a lignite and its demineralized derivative with calcium or potassium catalyst precursors containing acetate (CH{sub 3}COO{minus}), chloride (Cl{minus}), nitrate (NO{sub 3}{minus}), sulfate (SO{sub 4}{sup 2{minus}}), and carbonate (CO{sub 3}{sup 2{minus}}) anions. Catalyst loading will be conducted under well-controlled conditions of solution pH and ionic strength.

  15. Synthesis of boron carbide via poly(vinylpentaborane) precursors

    SciTech Connect

    Mirabelli, M.G.L.; Sneddon, L.G.

    1988-05-11

    Limitations in traditional ceramic processing have encouraged interest in the development and utilization of polymer pyrolyses as low-temperature synthetic routes to nonoxide ceramic materials. Boron carbide is an example of a material where preparation from a polymer precursor might offer advantages over conventional synthetic techniques. Mixed B/sub 4/C-SiC ceramics have, in fact, been previously obtained from pyrolysis of poly(carboranesiloxane) polymers; however, a synthesis of pure B/sub 4/C from polymeric precursors has heretofore not been developed. They report here that 2-(H/sub 2/C=CH)-B/sub 5/H/sub 8/ will undergo thermal polymerization to vinylpentaborane oligomers and that these species can be converted to pure boron carbide (B/sub 4/C) in high ceramic yields under mild conditions.

  16. Turbulence-induced magnetic fields in shock precursors

    NASA Astrophysics Data System (ADS)

    del Valle, M. V.; Lazarian, A.; Santos-Lima, R.

    2016-02-01

    Galactic cosmic rays are believed to be mostly accelerated at supernova shocks. However, the interstellar magnetic field is too weak to efficiently accelerate galactic cosmic rays up to the highest energies, i.e. 1015 eV. A stronger magnetic field in the pre-shock region could provide the efficiency required. Bell's cosmic-ray nonresonant streaming instability has been claimed to be responsible for the amplification of precursor magnetic fields. However, an alternative mechanism has been proposed in which the cosmic-ray pressure gradient forms the shock precursor and drives turbulence, amplifying the magnetic field via the small-scale dynamo. A key ingredient for the mechanism to operate are the inhomogeneities present in the interstellar medium (ISM). These inhomogeneities are the consequence of turbulence. In this work we explore the magnetic field amplification in different ISM conditions through 3D MHD numerical simulations.

  17. Detection of hydrothermal precursors to large northern california earthquakes.

    PubMed

    Silver, P G; Valette-Silver, N J

    1992-09-01

    During the period 1973 to 1991 the interval between eruptions from a periodic geyser in Northern California exhibited precursory variations 1 to 3 days before the three largest earthquakes within a 250-kilometer radius of the geyser. These include the magnitude 7.1 Loma Prieta earthquake of 18 October 1989 for which a similar preseismic signal was recorded by a strainmeter located halfway between the geyser and the earthquake. These data show that at least some earthquakes possess observable precursors, one of the prerequisites for successful earthquake prediction. All three earthquakes were further than 130 kilometers from the geyser, suggesting that precursors might be more easily found around rather than within the ultimate rupture zone of large California earthquakes. PMID:17738277

  18. Precursors and metabolic pathway for guaiacol production by Alicyclobacillus acidoterrestris.

    PubMed

    Cai, Rui; Yuan, Yahong; Wang, Zhouli; Guo, Chunfeng; Liu, Bin; Liu, Laping; Wang, Yutang; Yue, Tianli

    2015-12-01

    Alicyclobacillus acidoterrestris has recently received much attention due to its implication in the spoilage of pasteurized fruit juices, which was manifested by the production of guaiacol. Vanillic acid and vanillin have been accepted as the biochemical precursors of guaiacol in fruit juices. The purpose of this study was to try to find other precursors and elucidate details about the conversion of vanillic acid and vanillin to guaiacol by A. acidoterrestris. Four potential substrates including ferulic acid, catechol, phenylalanine and tyrosine were analyzed, but they could not be metabolized to guaiacol by all the thirty A. acidoterrestris strains tested. Resting cell studies and enzyme assays demonstrated that vanillin was reduced to vanillyl alcohol by NADPH-dependent vanillin reductase and oxidized to vanillic acid by NAD(P)(+)-dependent vanillin dehydrogenases in A. acidoterrestris DSM 3923. Vanillic acid underwent a nonoxidative decarboxylation to guaiacol. The reversible vanillic acid decarboxylase involved was oxygen insensitive and pyridine nucleotide-independent. PMID:26241489

  19. Low-temperature nitridation of Fe nanoparticles precursor.

    PubMed

    Huang, H; Lu, B; Lei, J P; Dong, X L

    2009-12-01

    Nitridation of Fe nanoparticle precursor was performed in a NH3 atmosphere at the temperatures of 473 K and 673 K for one hour. Fe nanoparticles precursor had a typical spherical shape with iron oxides shell and alpha-Fe core, which was obtained by an arc-discharge method. Up to date, the nitriding temperature of 473 K in present work was the lowest by thermal ammonolysis method because of the characteristics of the nano-sized particles. The resultant product after nitridation was a mixture of iron-nitrides (gamma'-Fe4N and epsilon-Fe3N) nanoparticles with homogeneous dispersion. The nitriding mechanism, oxidizing behaviors and magnetic properties of iron-nitride nanoparticles were measured and discussed. PMID:19908793

  20. Turbulence-induced magnetic fields in shock precursors

    NASA Astrophysics Data System (ADS)

    del Valle, M. V.; Lazarian, A.; Santos-Lima, R.

    2016-05-01

    Galactic cosmic rays are believed to be mostly accelerated at supernova shocks. However, the interstellar magnetic field is too weak to efficiently accelerate galactic cosmic rays up to the highest energies, i.e. 1015 eV. A stronger magnetic field in the pre-shock region could provide the efficiency required. Bell's cosmic ray non-resonant streaming instability has been claimed to be responsible for the amplification of precursor magnetic fields. However, an alternative mechanism has been proposed in which the cosmic ray pressure gradient forms the shock precursor and drives turbulence, amplifying the magnetic field via the small-scale dynamo. Key ingredients for the mechanism to operate are the inhomogeneities present in the interstellar medium. These inhomogeneities are the consequence of turbulence. In this work we explore the magnetic field amplification in different interstellar medium conditions through 3D magnetohydrodynamic numerical simulations.

  1. Possible precursors to the 2011 3/11 Japan earthquake:

    NASA Astrophysics Data System (ADS)

    Hayakawa, M.; Hobara, Y.; Schekotov, A.; Rozhnoi, A.; Solovieva, M.

    2012-04-01

    The purpose of this paper is to present a possible precursor to the 2011 March 11 Japan earthquake. First of all, we present the results on subionospheric VLF/LF propagation anomaly (ionospheric perturbation) by means of Japan-Russia VLF network. It is found that the ionospheric perturbation is clearly detected on March 4, 5 and 6 on the propagation paths of NLK (Seattle, USA) to Japanese stations and on a path of JJI (Miyazaki, Kyushu) to Kamchatka. Next, we present the results on the ULF depression (horizontal component) on the same days, which is interpreted in terms of the absorption in the disturbed lower ionosphere of the downgoing magnetospheric Alfve'n waves. These two precursors are considered to be due to the same effect of the lower ionospheric perturbation about one week before the earthquake.

  2. Boron/Carbon/Silicon/Nitrogen Ceramics And Precursors

    NASA Technical Reports Server (NTRS)

    Riccitiello, Salvatore; Hsu, Ming TA; Chen, Timothy S.

    1996-01-01

    Ceramics containing various amounts of boron, carbon, silicon, and nitrogen made from variety of polymeric precursors. Synthesized in high yield from readily available and relatively inexpensive starting materials. Stable at room temperature; when polymerized, converted to ceramics in high yield. Ceramics resist oxidation and other forms of degradation at high temperatures; used in bulk to form objects or to infiltrate other ceramics to obtain composites having greater resistance to oxidation and high temperatures.

  3. Hydroxycinnamic acid ethyl esters as precursors to ethylphenols in wine.

    PubMed

    Hixson, Josh L; Sleep, Nicola R; Capone, Dimitra L; Elsey, Gordon M; Curtin, Christopher D; Sefton, Mark A; Taylor, Dennis K

    2012-03-01

    A method for determining ethyl coumarate and ethyl ferulate in wine using GC-MS with deuterium-labeled analogues has been developed and used to measure the evolution of these two esters during the production of two commercial monovarietal red wines, cv. Grenache and Shiraz. During fermentation, the concentration of ethyl coumarate rose from low levels to 0.4 mg/L in Grenache and 1.6 mg/L in Shiraz wines. These concentrations then increased further during barrel aging to 1.4 and 3.6 mg/L, respectively. The concentration of ethyl ferulate was much lower, reaching a maximum of only 0.09 mg/L. Conversion of ethyl coumarate and ethyl ferulate to their corresponding ethylphenols was observed during fermentations of a synthetic medium with two strains of Dekkera bruxellensis (AWRI 1499 and AWRI 1608), while a third (strain AWRI 1613) produced no ethylphenols at all from these precursors. Strains AWRI 1499 and 1608 produced 4-ethylphenol from ethyl coumarate in 68% and 57% yields, respectively. The corresponding yields of 4-ethylguaiacol from ethyl ferulate were much lower, 7% and 3%. Monitoring of ethyl coumarate and ethyl ferulate concentration during the Dekkera fermentations showed that the selectivity for ethylphenol production according to yeast strain and the precursor was principally a result of variation in esterase activity. Consequently, ethyl coumarate can be considered to be a significant precursor to 4-ethylphenol in wines affected by these two strains of Brettanomyces/Dekkera yeast, while ethyl ferulate is not an important precursor to 4-ethylguaiacol. PMID:22324721

  4. Characterizing the signature of flame flashback precursor through recurrence analysis.

    PubMed

    Christodoulou, Loizos; Kabiraj, Lipika; Saurabh, Aditya; Karimi, Nader

    2016-01-01

    In this paper, it is shown that prior to flashback, small dynamical changes appear in the system. These changes appear as a drift in the recurrence plots and are found to be associated with a gradual increase in the determinism and recurrence rate. Thus, this study indicates that precursors to flame flashback exist and can be detected in the multidimensional phase space reconstructed from pressure measurements acquired during flashback. This observation could have broad academic as well as industrial implications. PMID:26826862

  5. Characterizing the signature of flame flashback precursor through recurrence analysis

    NASA Astrophysics Data System (ADS)

    Christodoulou, Loizos; Kabiraj, Lipika; Saurabh, Aditya; Karimi, Nader

    2016-01-01

    In this paper, it is shown that prior to flashback, small dynamical changes appear in the system. These changes appear as a drift in the recurrence plots and are found to be associated with a gradual increase in the determinism and recurrence rate. Thus, this study indicates that precursors to flame flashback exist and can be detected in the multidimensional phase space reconstructed from pressure measurements acquired during flashback. This observation could have broad academic as well as industrial implications.

  6. COS in the stratosphere. [sulfuric acid aerosol precursor

    NASA Technical Reports Server (NTRS)

    Inn, E. C. Y.; Vedder, J. F.; Tyson, B. J.; Ohara, D.

    1979-01-01

    Carbonyl sulfide (COS) has been detected in the stratosphere, and mixing ratio measurements are reported for altitudes of 15.2 to 31.2 km. A large volume, cryogenic sampling system mounted on board a U-2 aircraft has been used for lower stratosphere measurements and a balloon platform for measurement at 31.2 km. These observations and measurements strongly support the concept that stratospheric COS is an important precursor in the formation of sulfuric acid aerosols.

  7. Ataxin-1 regulates proliferation of hippocampal neural precursors.

    PubMed

    Asher, M; Johnson, A; Zecevic, B; Pease, D; Cvetanovic, M

    2016-05-13

    Polyglutamine expansion in the protein ATAXIN-1 (ATXN1) causes spinocerebellar ataxia type 1 (SCA1), an inherited neurodegenerative disease characterized by motor deficits, cognitive impairment and depression. Although ubiquitously expressed, mutant ATXN1 causes neurodegeneration primarily in the cerebellum, which is responsible for the observed motor deficits. The role of ATXN1 outside of the cerebellum and the causes of cognitive deficits and depression in SCA1 are less understood. In this study, we demonstrate a novel role of ATXN1 in the hippocampus as a regulator of adult neurogenesis. Adult hippocampal neurogenesis is the process of generating new hippocampal neurons and is linked to cognition and mood. We found that loss of ATXN1 causes a decrease in hippocampal neurogenesis in ATXN1 null (Atxn1(-/-)) mice. This decrease was caused by reduced proliferation of neural precursors in the hippocampus of Atxn1(-/-) mice, and persisted even when Atxn1(-/-) hippocampal neural precursors were removed from their natural environment and grown in vitro, suggesting that ATXN1 affects proliferation in a cell-autonomous manner. Moreover, expression of ATXN1 with a pathological polyglutamine (polyQ) expansion in wild-type neural precursor cells inhibited their proliferation. Our data establish a novel role for ATXN1 in the hippocampus as an intrinsic regulator of precursor cell proliferation, and suggest a mechanism by which polyQ expansion and loss of ATXN1 affect hippocampal function, potentially contributing to cognitive deficits and depression. These results indicate that while depletion of ATXN1 is a promising therapeutic approach to treat the cerebellar aspects of SCA1, this approach should be employed with caution given the potential for side effects on hippocampal function with loss of wild-type ATXN1. PMID:26876606

  8. New Ir Bis-Carbonyl Precursor for Water Oxidation Catalysis.

    PubMed

    Huang, Daria L; Beltrán-Suito, Rodrigo; Thomsen, Julianne M; Hashmi, Sara M; Materna, Kelly L; Sheehan, Stafford W; Mercado, Brandon Q; Brudvig, Gary W; Crabtree, Robert H

    2016-03-01

    This paper introduces Ir(I)(CO)2(pyalc) (pyalc = (2-pyridyl)-2-propanoate) as an atom-efficient precursor for Ir-based homogeneous oxidation catalysis. This compound was chosen to simplify analysis of the water oxidation catalyst species formed by the previously reported Cp*Ir(III)(pyalc)OH water oxidation precatalyst. Here, we present a comparative study on the chemical and catalytic properties of these two precursors. Previous studies show that oxidative activation of Cp*Ir-based precursors with NaIO4 results in formation of a blue Ir(IV) species. This activation is concomitant with the loss of the placeholder Cp* ligand which oxidatively degrades to form acetic acid, iodate, and other obligatory byproducts. The activation process requires substantial amounts of primary oxidant, and the degradation products complicate analysis of the resulting Ir(IV) species. The species formed from oxidation of the Ir(CO)2(pyalc) precursor, on the other hand, lacks these degradation products (the CO ligands are easily lost upon oxidation) which allows for more detailed examination of the resulting Ir(pyalc) active species both catalytically and spectroscopically, although complete structural analysis is still elusive. Once Ir(CO)2(pyalc) is activated, the system requires acetic acid or acetate to prevent the formation of nanoparticles. Investigation of the activated bis-carbonyl complex also suggests several Ir(pyalc) isomers may exist in solution. By (1)H NMR, activated Ir(CO)2(pyalc) has fewer isomers than activated Cp*Ir complexes, allowing for advanced characterization. Future research in this direction is expected to contribute to a better structural understanding of the active species. A diol crystallization agent was needed for the structure determination of 3. PMID:26901517

  9. AIMStar: Antimatter initiated microfusion for pre-cursor interstellar missions

    NASA Astrophysics Data System (ADS)

    Kramer, Kevin J.; Lewis, Raymond A.; Meyer, Kirby J.; Smith, Gerald A.; Howe, Steven D.

    2000-01-01

    We address the challenge of delivering a scientific payload to 10,000 A.U. in 50 years. This mission may be viewed as a pre-cursor to later missions to Alpha Centauri and beyond. We consider a small, nuclear fusion engine sparked by clouds of antiprotons, and describe the principle and operation of the engine and mission parameters. An R&D program currently in progress is discussed. .

  10. Observations of Electromagnetic Whistler Precursors at Supercritical Interplanetary Shocks

    NASA Technical Reports Server (NTRS)

    Wilson, L. B., III; Koval, A.; Szabo, Adam; Breneman, A.; Cattell, C. A.; Goetz, K.; Kellogg, P. J.; Kersten, K.; Kasper, J. C.; Maruca, B. A.; Pulupa, M.

    2012-01-01

    We present observations of electromagnetic precursor waves, identified as whistler mode waves, at supercritical interplanetary shocks using the Wind search coil magnetometer. The precursors propagate obliquely with respect to the local magnetic field, shock normal vector, solar wind velocity, and they are not phase standing structures. All are right-hand polarized with respect to the magnetic field (spacecraft frame), and all but one are right-hand polarized with respect to the shock normal vector in the normal incidence frame. They have rest frame frequencies f(sub ci) < f much < f(sub ce) and wave numbers 0.02 approx < k rho (sub ce) approx <. 5.0. Particle distributions show signatures of specularly reflected gyrating ions, which may be a source of free energy for the observed modes. In one event, we simultaneously observe perpendicular ion heating and parallel electron acceleration, consistent with wave heating/acceleration due to these waves. Al though the precursors can have delta B/B(sub o) as large as 2, fluxgate magnetometer measurements show relatively laminar shock transitions in three of the four events.

  11. Nanoparticle colloids as spray deposition precursors to CIGS photovoltaic materials

    NASA Astrophysics Data System (ADS)

    Schulz, Douglas L.; Curtis, Calvin J.; Flitton, Rebecca A.; Wiesner, Holm; Keane, James; Matson, Richard J.; Parilla, Philip A.; Noufi, Rommel; Ginley, David S.

    1997-02-01

    Cu-In-Ga-Se nanoparticle colloids have been used as precursors in the spray deposition of photovoltaic films. Precursor colloid was prepared by reaction of the metal iodides in pyridine with sodium selenide in methanol at reduced temperature according to one of two routes: synthesis of each of the component binary selenides (Type I) followed by physical mixing of the isolated particles; or a one-pot synthesis with all the metal iodides reacting together in one flask to form a mixed-metal Cu-In-Ga-Se colloid (Type II). The constituent nanoparticles in these colloids were analyzed by TEM and XRD and were determined to be amorphous as-synthesized. Crystalline phase formation of these nanoparticles was observed by XRD after a thermal treatment. These precursor colloids were sprayed onto Mo-coated glass substrates at elevated temperatures. The nanoparticle-derived Cu-In-Ga-Se films were characterized by SEM and XRD prior to being finished into CIGS solar cell devices according to standard NREL protocol. I-V characterization of these CIGS solar cells showed these devices are limited by a large series resistance.

  12. Laser synthesis of nanostructured ceramics from liquid precursors

    NASA Astrophysics Data System (ADS)

    Wilden, Johannes; Fischer, Georg

    2007-12-01

    The free-form net shape laser synthesis of nanostructured ceramics from liquid precursors enables a residual stress-free production of high temperature resistant ceramic units and components for the use in microsystem engineering. Due to the use of molecular compounded liquid, ceramic precursors the resulting ceramic components show outstanding properties, for example high purity and a nanostructured material design. The use of pulsed lasers enables a defined input of energy required to pyrolyse the precursor material into a crystalline ceramic, so the active volume can be reduced significantly compared to other processes, for example pyrolysis by furnace. In this paper several methods for a further minimization of the active volume are presented. The investigations determined different factors affecting the process. Realizing selective experiments allows a determination of their influencing level and the definition of a working area to produce three-dimensional components with high aspect ratio. By several studies, e.g., scanning electron microscopy, transmission electron microscopy as well as X-ray diffraction analysis, the atomic structure and composition of the created components were analyzed and valued, so the different reaction processes can be described extensively.

  13. Biotransformation of nitrosamines and precursor secondary amines under methanogenic conditions.

    PubMed

    Tezel, Ulas; Padhye, Lokesh P; Huang, Ching-Hua; Pavlostathis, Spyros G

    2011-10-01

    The biotransformation potential of six nitrosamines and their precursor secondary amines by a mixed methanogenic culture was investigated. Among the six nitrosamines tested, N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA), and N-nitrosopyrrolidine (NPYR) were almost completely degraded but only when degradable electron donors were available. On the contrary, N-nitrosodiethylamine (NDEA), N-nitrosodipropylamine (NDPA), and N-nitrosodibutylamine (NDBA) were not degraded. Three precursor secondary amines, corresponding to the three biodegradable nitrosamines, were also completely utilized even with very low levels of available electron donors. The secondary amine precursors of the three, nonbiodegradable nitrosamines were also recalcitrant. A bioassay conducted to elucidate the biotransformation pathway of NDMA in the mixed methanogenic culture using H(2) as the electron donor showed that NDMA was utilized as an electron acceptor and transformed to dimethylamine (DMA), which in turn was degraded to ammonia and methane. The H(2) threshold concentration for NDMA bioreduction ranged between 0.0017 and 0.031 atm. Such a high H(2) threshold concentration suggests that in mixed methanogenic cultures, NDMA reducers are weak competitors to other, H(2)-consuming microbial species, such as homoacetogens and methanogens. Thus, complete removal of nitrosamines in anaerobic digestion systems, where the H(2) partial pressure is typically below 10(-4) atm, is difficult to achieve. PMID:21863807

  14. Development of techniques for tagging precursor and essential chemicals

    SciTech Connect

    Swansiger, W.A.; Shepodd, T.J.; Phillips, M.L.F.

    1994-01-01

    The ability to identify the manufacturers and distributors of chemicals seized in raids of illicit drug labs would be of great value in controlling the diversion of these chemicals. We developed a tagging scheme based on the addition of sub-ppM concentrations of various combinations of rare-earth elements to the target chemicals and evaluated a number of techniques for detecting the tags. We developed soluble tags for tagging liquids and selected Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) as the preferred detection technique. We developed insoluble tags for tagging solids and developed methods to analyze them and mix them into solid precursors. We have successfully demonstrated the tagging of several solvents and two of the precursor chemicals used in one of the most popular clandestine methamphetamine syntheses (ephedrine reacting with hydriodic acid/red phosphorus). The tagging scheme is capable of yielding tens of thousands of signatures (using holmium as an internal standard and up to 9 rare-earths at up to 3 concentrations yields 3{sup 9} {minus} 1 = 19,682 signatures) and is applicable to most of the chemicals on the precursor and essential chemicals list. In the concentrations employed, the tags are safe enough to be added to pharmaceuticals and cheap enough to tag tanker loads of chemicals.

  15. Oxidation and formation of deposit precursors in hydrocarbon fuels

    NASA Technical Reports Server (NTRS)

    Mayo, F. R.; Lan, B.; Cotts, D. B.; Buttrill, S. E., Jr.; St.john, G. A.

    1983-01-01

    The oxidation of two jet turbine fuels and some pure hydrocarbons was studied at 130 C with and without the presence of small amounts of N-methyl pyrrole (NMP) or indene. Tendency to form solid-deposit precursors was studied by measuring soluble gum formation as well as dimer and trimer formation using field ionization mass spectrometry. Pure n-dodecane oxidized fastest and gave the smallest amount of procursors. An unstable fuel oil oxidized much slower but formed large amounts of precursors. Stable Jet A fuel oxidized slowest and gave little precursors. Indene either retarded or accelerated the oxidation of n-dodecane, depending on its concentration, but always caused more gum formation. The NMP greatly retarded n-dodecane oxidation but accelerated Jet A oxidation and greatly increased the latter's gum formation. In general, the additive reacted faster and formed most of the gum. Results are interpreted in terms of classical cooxidation theory. The effect of oxygen pressure on gum formation is also reported.

  16. LWIR hyperspectral imaging application and detection of chemical precursors

    NASA Astrophysics Data System (ADS)

    Lavoie, Hugo; Thériault, Jean-Marc; Bouffard, François; Puckrin, Eldon; Dubé, Denis

    2012-10-01

    Detection and identification of Toxic industrial chemicals (TICs) represent a major challenge to protect and sustain first responder and public security. In this context, passive Hyperspectral Imaging (HSI) is a promising technology for the standoff detection and identification of chemical vapors emanating from a distant location. To investigate this method, the Department of National Defense and Public Safety Canada have mandated Defense Research and Development Canada (DRDC) - Valcartier to develop and test Very Long Wave Infrared (VLWIR) HSI sensors for standoff detection. The initial effort was focused to address the standoff detection and identification of toxic industrial chemicals (TICs), surrogates and precursors. Sensors such as the Improved Compact ATmospheric Sounding Interferometer (iCATSI) and the Multi-option Differential Detection and Imaging Fourier Spectrometer (MoDDIFS) were developed for this application. This paper presents the sensor developments and preliminary results of standoff detection and identification of TICs and precursors. The iCATSI and MoDDIFS sensors are based on the optical differential Fourier-transform infrared (FTIR) radiometric technology and are able to detect, spectrally resolve and identify small leak at ranges in excess of 1 km. Results from a series of trials in asymmetric threat type scenarios are reported. These results serve to establish the potential of passive standoff HSI detection of TICs, precursors and surrogates.

  17. Control of thin film processing behavior through precursor structural modifications

    SciTech Connect

    Schwartz, R.W.; Voigt, J.A.; Boyle, T.J.; Christenson, T.A.; Buchheit, C.D.

    1995-02-01

    In the sol-gel processing of ceramic thin films it has been frequently noted that the processing behavior, microstructure and properties of the films are dependent on the nature of the coating solution. In an attempt to understand such thin film processing-property relationships, the authors have systematically investigated the effects of varying the precursor nature on thin film densification and crystallization for ZrO{sub 2} and TiO{sub 2} films. Metal alkoxide starting compounds, e.g., zirconium n-butoxide{center_dot}n-butanol and titanium i-propoxide, were reacted with acetic acid and 2,4-pentanedione to prepare coating solutions for thin film deposition. The use of these chelating ligands resulted in solution oligomeric species of different nature. Studies of thin film processing indicated that film processing characteristics, i.e., consolidation, densification and crystallization, were strongly dependent on solution precursor nature. Ligand steric size, pyrolysis behavior, extent of chelation, and precursor reactivity were found to be key variables in controlling film processing characteristics.

  18. Myeloid/natural killer cell precursor acute leukemia with tetraploidy.

    PubMed

    Dinol, Gna?; Palandz, Skr; Nalaci, Meliha; Uur, Ali; Bykaydin, Banu

    2005-12-01

    Myeloid/natural killer (NK) cell precursor acute leukemia is characterized by coexpression of myeloid and natural killer cell antigens and an aggressive clinical course. Here we report a case of myeloid/NK precursor acute leukemia in a 37-year-old woman. Clinical presentation was correlated with leukemic blast morphology, immunophenotype, and cytogenetic analysis. The patient had noted fever, weakness, purpura, peripheral lymphadenopathy, and moderate hepatosplenomegaly. Peripheral blood smears and bone marrow aspirate smears at presentation revealed blastic cells, which were generally L2 shaped, with variation in cell size, round to moderately irregular nuclei and prominent nucleoli, pale cytoplasm, and a lack of azurophilic granules. Immunophenotypic analysis of the blasts displayed coexpression of myeloid and natural killer cell antigens with relatively immature phenotype: CD7+, CD33+, CD34+, CD56+, CD57+, CD16-, MPO-. Cytogenetic analysis of marrow cells showed 62% of cells with a normal female karyotype; in the remaining 38%, tetraploid changes were detected, where the chromosome number was 92, with no preferential losses or gains of chromosomes. Fluorescence in situ hybridization analysis revealed the same abnormality. The patient did not respond to chemotherapy (cytosine arabinoside and idarubicin) and died of a septic complication on the 34th day after admission. To our knowledge, this is the first description of tetraploidy in myeloid/NK cell precursor acute leukemia. PMID:16337859

  19. Assigning probability gain for precursors of four large Chinese earthquakes

    SciTech Connect

    Cao, T.; Aki, K.

    1983-03-10

    We extend the concept of probability gain associated with a precursor (Aki, 1981) to a set of precursors which may be mutually dependent. Making use of a new formula, we derive a criterion for selecting precursors from a given data set in order to calculate the probability gain. The probabilities per unit time immediately before four large Chinese earthquakes are calculated. They are approximately 0.09, 0.09, 0.07 and 0.08 per day for 1975 Haicheng (M = 7.3), 1976 Tangshan (M = 7.8), 1976 Longling (M = 7.6), and Songpan (M = 7.2) earthquakes, respectively. These results are encouraging because they suggest that the investigated precursory phenomena may have included the complete information for earthquake prediction, at least for the above earthquakes. With this method, the step-by-step approach to prediction used in China may be quantified in terms of the probability of earthquake occurrence. The ln P versus t curve (where P is the probability of earthquake occurrence at time t) shows that ln P does not increase with t linearly but more rapidly as the time of earthquake approaches.

  20. Latest Developments in Suspension and Liquid Precursor Thermal Spraying

    NASA Astrophysics Data System (ADS)

    Fauchais, Pierre; Montavon, Ghislain

    2010-01-01

    The interest to manufacture onto large surfaces thick (i.e., 10-20 μm, average thickness) finely structured or nanostructured layers is increasingly growing since the past 10 years. This explains the interest for suspension thermal spraying (STS) and solution precursor thermal spraying (SPTS), both allowing manufacturing finely structured layers of thicknesses varying between a few micrometers up to a few hundreds of micrometers. STS aims at processing a suspension of sub-micrometer-sized or even nanometer-sized solid particles dispersed in a liquid phase. The liquid phase permits the injection of particles in the thermal flow (i.e., due to their size, a carrier gas cannot play this role). SPTS aims at processing a solution of precursors under the same conditions. Upon evaporation of the liquid phase, the precursor concentration increases until precipitation, pyrolysis, and melting of small droplets occur. Compared to conventional thermal spray routes, STS and SPTS are by far more complex because fragmentation and vaporization of the liquid control the coating build-up mechanisms. Numerous studies are still necessary to reach a better understanding of the involved phenomena and to further develop the technology, among which are injection systems, suspension and solution optimizations, spray kinematics, etc. This review presents some recent developments and our present knowledge in this field together with the available tools implemented to characterize the plasma-liquid interaction and the coating formation.

  1. Accident sequence precursor events with age-related contributors

    SciTech Connect

    Murphy, G.A.; Kohn, W.E.

    1995-12-31

    The Accident Sequence Precursor (ASP) Program at ORNL analyzed about 14.000 Licensee Event Reports (LERs) filed by US nuclear power plants 1987--1993. There were 193 events identified as precursors to potential severe core accident sequences. These are reported in G/CR-4674. Volumes 7 through 20. Under the NRC Nuclear Plant Aging Research program, the authors evaluated these events to determine the extent to which component aging played a role. Events were selected that involved age-related equipment degradation that initiated an event or contributed to an event sequence. For the 7-year period, ORNL identified 36 events that involved aging degradation as a contributor to an ASP event. Except for 1992, the percentage of age-related events within the total number of ASP events over the 7-year period ({approximately}19%) appears fairly consistent up to 1991. No correlation between plant ape and number of precursor events was found. A summary list of the age-related events is presented in the report.

  2. High Divergence of the Precursor Peptides in Combinatorial Lanthipeptide Biosynthesis

    PubMed Central

    2015-01-01

    Lanthionine-containing peptides (lanthipeptides) are a rapidly growing family of polycyclic peptide natural products belonging to the large class of ribosomally synthesized and post-translationally modified peptides (RiPPs). These compounds are widely distributed in taxonomically distant species, and their biosynthetic systems and biological activities are diverse. A unique example of lanthipeptide biosynthesis is the prochlorosin synthetase ProcM from the marine cyanobacterium Prochlorococcus MIT9313, which transforms up to 29 different precursor peptides (ProcAs) into a library of lanthipeptides called prochlorosins (Pcns) with highly diverse sequences and ring topologies. Here, we show that many ProcM-like enzymes from a variety of bacteria have the capacity to carry out post-translational modifications on highly diverse precursor peptides, providing new examples of natural combinatorial biosynthesis. We also demonstrate that the leader peptides come from different evolutionary origins, suggesting that the combinatorial biosynthesis is tied to the enzyme and not a specific type of leader peptide. For some precursor peptides encoded in the genomes, the leader peptides apparently have been truncated at the N-termini, and we show that these N-terminally truncated peptides are still substrates of the enzymes. Consistent with this hypothesis, we demonstrate that about two-thirds of the ProcA N-terminal sequence is not essential for ProcM activity. Our results also highlight the potential of exploring this class of natural products by genome mining and bioengineering. PMID:25244001

  3. Phylogenetic appearance of Neuropeptide S precursor proteins in tetrapods

    PubMed Central

    Reinscheid, Rainer K.

    2007-01-01

    Sleep and emotional behavior are two hallmarks of vertebrate animal behavior, implying that specialized neuronal circuits and dedicated neurochemical messengers may have been developed during evolution to regulate such complex behaviors. Neuropeptide S (NPS) is a newly identified peptide transmitter that activates a typical G protein-coupled receptor. Central administration of NPS produces profound arousal, enhances wakefulness and suppresses all stages of sleep. In addition, NPS can alleviate behavioral responses to stress by producing anxiolytic-like effects. A bioinformatic analysis of current genome databases revealed that the NPS peptide precursor gene is present in all vertebrates with the exception of fish. A high level of sequence conservation, especially of aminoterminal structures was detected, indicating stringent requirements for agonist-induced receptor activation. Duplication of the NPS precursor gene was only found in one out of two marsupial species with sufficient genome coverage (Monodelphis domestica; opossum), indicating that the duplicated opossum NPS sequence might have arisen as an isolated event. Pharmacological analysis of both Monodelphis NPS peptides revealed that only the closely related NPS peptide retained agonistic activity at NPS receptors. The duplicated precursor might be either a pseudogene or could have evolved different receptor selectivity. Together, these data show that NPS is a relatively recent gene in vertebrate evolution whose appearance might coincide with its specialized physiological functions in terrestrial vertebrates. PMID:17293003

  4. A conserved threonine spring-loads precursor for intein splicing

    PubMed Central

    Dearden, Albert K; Callahan, Brian; Roey, Patrick Van; Li, Zhong; Kumar, Utsav; Belfort, Marlene; Nayak, Saroj K

    2013-01-01

    Protein splicing is an autocatalytic process where an “intein” self-cleaves from a precursor and ligates the flanking N- and C-“extein” polypeptides. Inteins occur in all domains of life and have myriad uses in biotechnology. Although the reaction steps of protein splicing are known, mechanistic details remain incomplete, particularly the initial peptide rearrangement at the N-terminal extein/intein junction. Recently, we proposed that this transformation, an N-S acyl shift, is accelerated by a localized conformational strain, between the intein's catalytic cysteine (Cys1) and the neighboring glycine (Gly-1) in the N-extein. That proposal was based on the crystal structure of a catalytically competent trapped precursor. Here, we define the structural origins and mechanistic relevance of the conformational strain using a combination of quantum mechanical simulations, mutational analysis, and X-ray crystallography. Our results implicate a conserved, but largely unstudied, threonine residue of the Ssp DnaE intein (Thr69) as the mediator of conformational strain through hydrogen bonding. Further, the strain imposed by this residue is shown to position the splice junction in a manner that enhances the rate of the N-S acyl shift substantially. Taken together, our results not only provide fundamental understanding of the control of the first step of protein splicing but also have important implications in various biotechnological applications that require precursor manipulation. PMID:23423655

  5. A committed hemopoietic precursor to innate lymphoid cells

    PubMed Central

    Constantinides, Michael G.; McDonald, Benjamin D.; Verhoef, Philip A.; Bendelac, Albert

    2014-01-01

    Innate lymphoid cells (ILC) specialize in the rapid secretion of polarized sets of cytokines and chemokines to combat infection and promote tissue repair at mucosal barriers.1–9 Their diversity and similarities with previously characterized NK cells and lymphoid tissue inducers (LTi) have prompted a provisional classification of all innate lymphocytes into groups 1, 2 and 3 based solely on cytokine properties,10 but their developmental pathways and lineage relationships remain elusive. Using lineage tracing and transfer studies, we identified and characterized a novel subset of lymphoid precursors in fetal liver and adult bone marrow that transiently expressed high amounts of PLZF, a transcription factor previously associated with NKT cell development.11,12 PLZFhigh cells were committed ILC progenitors with multiple ILC1, ILC2 and ILC3 potential at the clonal level. They excluded classical LTi and NK cells, but included a peculiar subset of NK1.1+DX5− ‘NK-like’ cells residing in the liver. Deletion of PLZF markedly altered the development of several ILC subsets, but not LTi or NK cells. PLZFhigh precursors also expressed high amounts of Id2 and GATA3, as well as TOX, a known regulator of PLZF-independent NK and LTi lineages.13 These findings establish novel lineage relationships between ILC, NK and LTi cells, and identify the common precursor to ILC, termed ILCP. They also reveal the broad, defining role of PLZF in the differentiation of innate lymphocytes. PMID:24509713

  6. Precursors in the preparation of transition metal nitrides and transition metal carbonitrides and their reaction intermediates

    DOEpatents

    Maya, Leon

    1991-01-01

    A process for making ammonolytic precursors to nitride and carbonitride ceramics. Extreme reaction conditions are not required and the precursor is a powder-like substance that produces ceramics of improved purity and morphology upon pyrolysis.

  7. Precursor Analysis for Flight- and Ground-Based Anomaly Risk Significance Determination

    NASA Technical Reports Server (NTRS)

    Groen, Frank

    2010-01-01

    This slide presentation reviews the precursor analysis for flight and ground based anomaly risk significance. It includes information on accident precursor analysis, real models vs. models, and probabilistic analysis.

  8. Spectroscopic Characterization of Isolated FeMoco Precursor from NifEN**

    PubMed Central

    Fay, Aaron W.; Blank, Michael A.; Lee, Chi Chung

    2012-01-01

    The FeMoco of Mo-nitrogenase provides the active site for substrate reduction. Previously, a FeMoco precursor was captured on NifEN, a scaffold protein for FeMoco biosynthesis. Here, we report the isolation of FeMoco precursor from NifEN. The integrity of the precursor is reflected by the restoration of the precursor-specific EPR signal, as well as the full proficiency of the precursor in biosynthesis and catalysis upon its incorporation into the precursor-deficient NifEN. Moreover, XAS/EXAFS analysis supports the eight-iron model of the precursor, suggesting that the insertion of heterometal into the precursor involves exchanging one terminal iron atom for a molybdenum atom. PMID:21726031

  9. Analysis of electrical brain waves in neurotoxicology: γ-hydroxybutyrate.

    PubMed

    Binienda, Z K; Beaudoin, M A; Thorn, B T; Ali, S F

    2011-03-01

    Advances in computer technology have allowed quantification of the electroencephalogram (EEG) and expansion of quantitative EEG (qEEG) analysis in neurophysiology, as well as clinical neurology, with great success. Among the variety of techniques in this field, frequency (spectral) analysis using Fast Fourier Transforms (FFT) provides a sensitive tool for time-course studies of different compounds acting on particular neurotransmitter systems. Studies presented here include Electrocorticogram (ECoG) analysis following exposure to a glutamic acid analogue - domoic acid (DOM), psychoactive indole alkaloid - ibogaine, as well as cocaine and gamma-hydroxybutyrate (GHB). The ECoG was recorded in conscious rats via a tether and swivel system. The EEG signal frequency analysis revealed an association between slow-wave EEG activity delta and theta and the type of behavioral seizures following DOM administration. Analyses of power spectra obtained in rats exposed to cocaine alone or after pretreatment with ibogaine indicated the contribution of the serotonergic system in ibogaine mediated response to cocaine (increased power in alpha(1) band). Ibogaine also lowered the threshold for cocaine-induced electrographic seizures (increased power in the low-frequency bands, delta and theta). Daily intraperitoneal administration of cocaine for two weeks was associated with a reduction in slow-wave ECoG activity 24 hrs following the last injection when compared with controls. Similar decreased cortical activity in low-frequency bands observed in chronic cocaine users has been associated with reduced metabolic activity in the frontal cortex. The FFT analyses of power spectra relative to baseline indicated a significant energy increase over all except beta(2) frequency bands following exposure to 400 and 800 mg/kg GHB. The EEG alterations detected in rats following exposure to GHB resemble absence seizures observed in human petit mal epilepsy. Spectral analysis of the EEG signals combined with behavioral observations may prove to be a useful approach in studying chronic exposure to drugs of abuse and treatment of drug dependence. PMID:21886596

  10. Latent gel electrolyte precursors for quasi-solid dye sensitized solar cells.

    PubMed

    Kato, Takehito; Okazaki, Akio; Hayase, Shuzi

    2005-01-21

    New latent chemically-cross-linked gel electrolyte precursors for quasi-solid dye sensitized solar cells (QDSC) are reported. The gel electrolyte precursors consist of nano-particles and dicarboxylic acids as the latent gelators. The viscosity of the precursor is low at first and does not increase during storage at room temperature. However, when the precursor is baked at 80 degrees C, it solidifies immediately. Photo-voltaic performance is maintained after solidification. PMID:15645038

  11. What You Need to Know about Drugs: GHB

    MedlinePlus

    ... who go to "rave parties," including teens and young adults. Its side effects can be very dangerous, especially if the drug is mixed with alcohol . Sometimes Called: Liquid Ecstasy, G, Georgia Home Boy, ...

  12. Groundwater Ion Content Precursors of Strong Earthquakes in Kamchatka (Russia)

    NASA Astrophysics Data System (ADS)

    Biagi, P. F.; Ermini, A.; Kingsley, S. P.; Khatkevich, Y. M.; Gordeev, E. I.

    The Kamchatka peninsula, located in the far east of Russia, is a geologically active margin where the Pacific plate subducts beneath the North American and Eurasia plates. This area is characterised by frequent and strong seismic activity (magnitudes reaching 8.6) and epicentres are generally distributed offshore along the eastern coast of the peninsula. For many years, hydrogeochemicals have been sampled with a mean interval of three days to measure the most common ions in the groundwater of five deep wells in the southern area of the Kamchatka peninsula. In the last decade, five earthquakes with M > 6.5 have occurred at distances less than 250 km from these wells. These earthquakes were powerful enough for them to be considered as potential originators of precursors. In order to reveal possible precursors of these earthquakes, we analysed the groundwater ion contents. The quasi-periodic annual variation was filtered out, together with other slow trends, and then we smoothed out the high frequency fluctuations that arise from errors in a single measurement. When examining the data, we labelled each signal with an amplitude greater than three times the standard deviation as an irregularity and we made a first attempt at defining an anomaly as an irregularity occurring simultaneously in more than one parameter at each well. In a second definition we used the existence of an irregularity occurring simultaneously in each ion at more than one well. Then, on the basis of past results worldwide and the time interval between the earthquakes observed, we chose 158 days as the maximum temporal window between a possible anomaly and the subsequent earthquake. With the first anomaly definition we identified 6 anomalies with 4 possible successes and 2 failures. For the five earthquakes considered capable of producing precursors we obtained precursors in three cases. With the second anomaly definition we identified 10 anomalies with 7 possible successes and 3 failures and we obtained precursors in four of the five earthquakes. A schematic model explaining aspects of the complex relationship linking earthquakes and ion content anomalies is also presented.

  13. Preparation of Bi-Sr-Ca-Cu-O superconductors from oxide-glass precursors

    DOEpatents

    Hinks, David G.; Capone, II, Donald W.

    1992-01-01

    A superconductor and precursor therefor from oxide mixtures of Ca, Sr, Bi and Cu. Glass precursors quenched to elevated temperatures result in glass free of crystalline precipitates having enhanced mechanical properties. Superconductors are formed from the glass precursors by heating in the presence of oxygen to a temperature below the melting point of the glass.

  14. Liquid precursor for deposition of indium selenide and method of preparing the same

    SciTech Connect

    Curtis, Calvin J.; Miedaner, Alexander; van Hest, Marinus Franciscus Antonius Maria; Ginley, David S.; Hersh, Peter A.; Eldada, Louay; Stanbery, Billy J.

    2015-09-22

    Liquid precursors containing indium and selenium suitable for deposition on a substrate to form thin films suitable for semiconductor applications are disclosed. Methods of preparing such liquid precursors and method of depositing a liquid precursor on a substrate are also disclosed.

  15. Functional Analysis of Precursors for Serious Problem Behavior and Related Intervention

    ERIC Educational Resources Information Center

    Langdon, Nancy A.; Carr, Edward G.; Owen-DeSchryver, Jamie S.

    2008-01-01

    Precursor behaviors are innocuous behaviors that reliably precede the occurrence of problem behavior. Intervention efforts applied to precursors might prevent the occurrence of severe problem behavior. We examined the relationship between precursor behavior and problem behavior in three individuals with developmental disabilities. First, a

  16. Progressing from Identification and Functional Analysis of Precursor Behavior to Treatment of Self-Injurious Behavior

    ERIC Educational Resources Information Center

    Dracobly, Joseph D.; Smith, Richard G.

    2012-01-01

    This multiple-study experiment evaluated the utility of assessing and treating severe self-injurious behavior (SIB) based on the outcomes of a functional analysis of precursor behavior. In Study 1, a precursor to SIB was identified using descriptive assessment and conditional probability analyses. In Study 2, a functional analysis of precursor

  17. Possibility to study ionospheric earthquakes precursors using CubeSats

    NASA Astrophysics Data System (ADS)

    Korepanov, Valery; Lappas, Vaios

    It is generally accepted that the earthquakes (EQ) are the most dangerous natural phenomena leading to the multiple losses in human lives and economics. The space observations must be included into the global chain of the EQ precursors monitoring at least as the initial warning to pay greater attention to the ground segment data. As the common opinion agrees, only in combination of multiple observation sites and set of monitored parameters the further progress at the way to raise EQ precursors detection probability may be obtained. There is necessary to answer two important questions before to plan any experiment to study ionospheric precursors of EQ. First one - whether the variations in the ionosphere definitely connected with the EQ preparation process do exist, and the second one - if they do, whether using these signals the precursors of EQ can be reliably identified and used for, if not prediction, then for the warning that the EQ in the given area approaches. The first successful mission dedicated to this problem solution was DEMETER (in orbit during more than 6 years from June 2004 until December 2010). The statistics of this study is impressive: altogether, about 9000 EQs with magnitude larger than M = 5.0 and depth lower than 40 km occurred all over the world during the analyzed period. In the result, the conclusion made there suggests that, obviously, there are real perturbations in the ionosphere connected with the seismic activity, but they are rather weak and at the present stage of data processing may be revealed only with the help of statistical analysis. To realize the study of ionospheric precursors, first it is imperative to clarify the mechanism of energy transfer along the chain “lithosphere-atmosphere-ionosphere”. Many hypotheses of such a mechanism exist, from which the mostly supported are fair weather currents (FWC) and atmospheric gravity waves (AGW), both of which have their pros and contras. The following minimal set of physical values may be advisable to measure to study them: if for FWC - electrons density and temperature and electric field variations, if for AGW - neutral particles concentration and magnetic fields variations, and TEC variations and thermal anomalies at the Earth’s surface and in the atmosphere for both. Also it became clear that the monitoring has to be made minimum in two, better in three points, preferably with the possibility to control the distance between them. This will increase the possibility to extract the seismogenic variations, being mostly local, at the background of the variations of other nature, being mostly enough spacious or even global. Taking into account the present and predictable reduction of the expenses for space scientific research, it would be extremely important to realize such a multi-point mission using the cheapest carriers - nanosatellites, especially cubesats. The analysis of both aspects of this problem - FWC and AGW mechanisms validation and the availability of miniaturized but enough sensitive scientific instrumentation, able to operate onboard cubesats, is made in the report. It shows that the scientific payload creation to realize the given task with the cubesats swarm is possible, including mini-thrusters able realizing the cubesats maneuvers on the orbit to control the distance between satellites. This allows us to come to conclusion that the realization of the cubesat project dedicated to the further study of important problem - detection of EQ precursors from space - may be put into practice at the present step of space science and technology development. Both necessary conditions - existence of scientific and experimental substantiation and of corresponding nanosatellite technology - are fulfilled. These works were partially supported by SSAU Contract No 1-16/12 and EC Framework 7 funded project 312993.

  18. Radiative precursors driven by converging blast waves in noble gases

    SciTech Connect

    Burdiak, G. C.; Lebedev, S. V.; Harvey-Thompson, A. J.; Swadling, G. F.; Suzuki-Vidal, F.; Hall, G. N.; Khoory, E.; Pickworth, L.; Bland, S. N.; Grouchy, P. de; Skidmore, J.; Suttle, L.; Bennett, M.; Niasse, N. P. L.; Williams, R. J. R.; Blesener, K.; Atoyan, L.; Cahill, A.; Hoyt, C.; Potter, W.; and others

    2014-03-15

    A detailed study of the radiative precursor that develops ahead of converging blast waves in gas-filled cylindrical liner z-pinch experiments is presented. The experiment is capable of magnetically driving 20 km s{sup −1} blast waves through gases of densities of the order 10{sup −5} g cm{sup −3} (see Burdiak et al. [High Energy Density Phys. 9(1), 52–62 (2013)] for a thorough description). Data were collected for Ne, Ar, and Xe gas-fills. The geometry of the setup allows a determination of the plasma parameters both in the precursor and across the shock, along a nominally uniform line of sight that is perpendicular to the propagation of the shock waves. Radiation from the shock was able to excite NeI, ArII, and XeII/XeIII precursor spectral features. It is shown that the combination of interferometry and optical spectroscopy data is inconsistent with upstream plasmas being in LTE. Specifically, electron density gradients do not correspond to any apparent temperature change in the emission spectra. Experimental data are compared to 1D radiation hydrodynamics HELIOS-CR simulations and to PrismSPECT atomic physics calculations to assist in a physical interpretation of the observations. We show that upstream plasma is likely in the process of being radiatively heated and that the emission from a small percentage of ionised atoms within a cool background plasma dominates the emission spectra. Experiments were carried out on the MAGPIE and COBRA pulsed-power facilities at Imperial College London and Cornell University, respectively.

  19. Plasma distribution and signaling activities of IGF-II precursors.

    PubMed

    Marks, Alicia G; Carroll, Julie M; Purnell, Jonathan Q; Roberts, Charles T

    2011-03-01

    IGF-II is thought to function through activation of the IGF-I receptor (IGF-IR) and the A isoform of the IR, with the IGF-IR being relevant to tumorigenesis and the IR to both tumorigenesis and metabolic control. In the paraneoplastic syndrome of nonislet cell tumor hypoglycemia, tumor-derived IGF-II has been proposed to exert both proliferative and metabolic effects, exemplifying this dual mode of action. Increased levels of IGF-II precursors ("big" and pro-IGF-II) have been reported in the circulation of nonislet cell tumor patients and have been proposed to exert greater or different effects than mature IGF-II. However, most studies have not defined which version is being investigated, and the relative activation of the IR and IGF-IR by IGF-II precursors has not been delineated. In this study, we determined the distribution of IGF-II isoforms in normal human plasma and their ability to activate the alternative versions of the IR. The majority (71%) of total IGF-II in human plasma was the mature form, while "big" and pro-IGF-II comprised 16% and 13%, respectively, with more variation seen in the levels of mature IGF-II. In IGF-IR-deficient cells expressing similar levels of human IR-A or IR-B, mature and "big" IGF-II exhibited similar activation of IR signaling, while pro-IGF-II exhibited significantly less activation. Downstream activation of Akt by mature and "big" IGF-II was greater in IR-A cells, consistent with previous reports of the greater affinity of IR-A for IGF-II. Thus, both IGF-II precursor forms are present in human plasma but do not preferentially activate the IR. PMID:21285309

  20. Radiative precursors driven by converging blast waves in noble gases

    NASA Astrophysics Data System (ADS)

    Burdiak, G. C.; Lebedev, S. V.; Harvey-Thompson, A. J.; Swadling, G. F.; Suzuki-Vidal, F.; Hall, G. N.; Khoory, E.; Pickworth, L.; Bland, S. N.; de Grouchy, P.; Skidmore, J.; Suttle, L.; Bennett, M.; Niasse, N. P. L.; Williams, R. J. R.; Blesener, K.; Atoyan, L.; Cahill, A.; Hoyt, C.; Potter, W.; Rosenberg, E.; Schrafel, P.; Kusse, B.

    2014-03-01

    A detailed study of the radiative precursor that develops ahead of converging blast waves in gas-filled cylindrical liner z-pinch experiments is presented. The experiment is capable of magnetically driving 20 km s-1 blast waves through gases of densities of the order 10-5 g cm-3 (see Burdiak et al. [High Energy Density Phys. 9(1), 52-62 (2013)] for a thorough description). Data were collected for Ne, Ar, and Xe gas-fills. The geometry of the setup allows a determination of the plasma parameters both in the precursor and across the shock, along a nominally uniform line of sight that is perpendicular to the propagation of the shock waves. Radiation from the shock was able to excite NeI, ArII, and XeII/XeIII precursor spectral features. It is shown that the combination of interferometry and optical spectroscopy data is inconsistent with upstream plasmas being in LTE. Specifically, electron density gradients do not correspond to any apparent temperature change in the emission spectra. Experimental data are compared to 1D radiation hydrodynamics HELIOS-CR simulations and to PrismSPECT atomic physics calculations to assist in a physical interpretation of the observations. We show that upstream plasma is likely in the process of being radiatively heated and that the emission from a small percentage of ionised atoms within a cool background plasma dominates the emission spectra. Experiments were carried out on the MAGPIE and COBRA pulsed-power facilities at Imperial College London and Cornell University, respectively.

  1. Precursor times of abnormal b-values prior to mainshocks

    NASA Astrophysics Data System (ADS)

    Wang, Jeen-Hwa; Chen, Kou-Cheng; Leu, Peih-Lin; Chang, Chien-Hsin

    2016-03-01

    Seismic observations exhibit the presence of abnormal b-values prior to numerous earthquakes. The time interval from the appearance of abnormal b-values to the occurrence of mainshock is called the precursor time. There are two kinds of precursor times in use: the first one denoted by T is the time interval from the moment when the b-value starts to increase from the normal one to the abnormal one to the occurrence time of the forthcoming mainshock, and the second one denoted by T p is the time interval from the moment when the abnormal b-value reaches the peak one to the occurrence time of the forthcoming mainshock. Let T* be the waiting time from the moment when the abnormal b-value returned to the normal one to the occurrence time of the forthcoming mainshock. The precursor time, T (usually in days), has been found to be related to the magnitude, M, of the mainshock expected in a linear form as log(T) = q + rM where q and r are the coefficient and slope, respectively. In this study, the values of T, T p , and T* of 45 earthquakes with 3 ≤ M ≤ 9 occurred in various tectonic regions are compiled from or measured from the temporal variations in b-values given in numerous source materials. The relationships of T and T p , respectively, versus M are inferred from compiled data. The difference between the values of T and T p decreases with increasing M. In addition, the plots of T*/T versus M, T* versus T, and T* versus T-T* will be made and related equations between two quantities will be inferred from given data.

  2. Accident Precursor Analysis and Management: Reducing Technological Risk Through Diligence

    NASA Technical Reports Server (NTRS)

    Phimister, James R. (Editor); Bier, Vicki M. (Editor); Kunreuther, Howard C. (Editor)

    2004-01-01

    Almost every year there is at least one technological disaster that highlights the challenge of managing technological risk. On February 1, 2003, the space shuttle Columbia and her crew were lost during reentry into the atmosphere. In the summer of 2003, there was a blackout that left millions of people in the northeast United States without electricity. Forensic analyses, congressional hearings, investigations by scientific boards and panels, and journalistic and academic research have yielded a wealth of information about the events that led up to each disaster, and questions have arisen. Why were the events that led to the accident not recognized as harbingers? Why were risk-reducing steps not taken? This line of questioning is based on the assumption that signals before an accident can and should be recognized. To examine the validity of this assumption, the National Academy of Engineering (NAE) undertook the Accident Precursors Project in February 2003. The project was overseen by a committee of experts from the safety and risk-sciences communities. Rather than examining a single accident or incident, the committee decided to investigate how different organizations anticipate and assess the likelihood of accidents from accident precursors. The project culminated in a workshop held in Washington, D.C., in July 2003. This report includes the papers presented at the workshop, as well as findings and recommendations based on the workshop results and committee discussions. The papers describe precursor strategies in aviation, the chemical industry, health care, nuclear power and security operations. In addition to current practices, they also address some areas for future research.

  3. Precursor lesions and prognostic factors in primary peritoneal serous carcinoma.

    PubMed

    Lee, Sandra; Nelson, Gregg; Duan, Quili; Magliocco, Anthony M; Duggan, Máire A

    2013-11-01

    Primary peritoneal serous carcinoma (PPSC) is uncommon and precursor lesions and prognostic factors are incompletely understood or described. Charts of 22 women with PPSC were reviewed for clinical and pathology data. Glass slides were reviewed for areas of PPSC, ovarian surface epithelium (OSE), ovarian cortical inclusion cysts (OCICs), tubal epithelial atypia (TEA), and serous tubal intraepithelial carcinoma (STIC). p53 and p16 immunohistochemical staining was scored and expression between the sites was compared. PPSC outcome was correlated with biomarker expression and clinicopathologic variables. p53 and p16 scores were significantly higher among PPSC and tubes than OSE and OCICs. Approximately 64% of PPSC, 46% of fallopian tubes, and none of the OSE overexpressed both biomarkers. OCICs were more frequently negative. Tubal pathologies of STIC, TEA and/or p53 signatures were present in approximately 46% of PPSC cases and the association with tubal p53 overexpression was significant. Statistically significant associations between tubal pathologies, OSE and OCICs biomarker expression profiles and their PPSC expression profiles did not occur. The median overall survival was 53 months and low-grade tumors had a better prognosis (P=0.02). A role for p53 and p16 overexpression in the formation of some PPSC, and p53 overexpression in the generation of precursor tubal pathology was identified. The high frequency of tubal pathology overexpressing p53 and low frequency of OSE and OCICs expressing either biomarker highlights a possible precursor role for the tube in some PPSC. Tumor grade was the only significant prognostic factor. PMID:24071870

  4. Cell Adhesion Signaling Regulates RANK Expression in Osteoclast Precursors

    PubMed Central

    Mochizuki, Ayako; Takami, Masamichi; Miyamoto, Yoichi; Nakamaki, Tsuyoshi; Tomoyasu, Shigeru; Kadono, Yuho; Tanaka, Sakae; Inoue, Tomio; Kamijo, Ryutaro

    2012-01-01

    Cells with monocyte/macrophage lineage expressing receptor activator of NF-κB (RANK) differentiate into osteoclasts following stimulation with the RANK ligand (RANKL). Cell adhesion signaling is also required for osteoclast differentiation from precursors. However, details of the mechanism by which cell adhesion signals induce osteoclast differentiation have not been fully elucidated. To investigate the participation of cell adhesion signaling in osteoclast differentiation, mouse bone marrow-derived macrophages (BMMs) were used as osteoclast precursors, and cultured on either plastic cell culture dishes (adherent condition) or the top surface of semisolid methylcellulose gel loaded in culture tubes (non-adherent condition). BMMs cultured under the adherent condition differentiated into osteoclasts in response to RANKL stimulation. However, under the non-adherent condition, the efficiency of osteoclast differentiation was markedly reduced even in the presence of RANKL. These BMMs retained macrophage characteristics including phagocytic function and gene expression profile. Lipopolysaccharide (LPS) and tumor necrosis factor –αTNF-α activated the NF-κB-mediated signaling pathways under both the adherent and non-adherent conditions, while RANKL activated the pathways only under the adherent condition. BMMs highly expressed RANK mRNA and protein under the adherent condition as compared to the non-adherent condition. Also, BMMs transferred from the adherent to non-adherent condition showed downregulated RANK expression within 24 hours. In contrast, transferring those from the non-adherent to adherent condition significantly increased the level of RANK expression. Moreover, interruption of cell adhesion signaling by echistatin, an RGD-containing disintegrin, decreased RANK expression in BMMs, while forced expression of either RANK or TNFR-associated factor 6 (TRAF6) in BMMs induced their differentiation into osteoclasts even under the non-adherent condition. These results suggest that cell adhesion signaling regulates RANK expression in osteoclast precursors. PMID:23139818

  5. Cell adhesion signaling regulates RANK expression in osteoclast precursors.

    PubMed

    Mochizuki, Ayako; Takami, Masamichi; Miyamoto, Yoichi; Nakamaki, Tsuyoshi; Tomoyasu, Shigeru; Kadono, Yuho; Tanaka, Sakae; Inoue, Tomio; Kamijo, Ryutaro

    2012-01-01

    Cells with monocyte/macrophage lineage expressing receptor activator of NF-κB (RANK) differentiate into osteoclasts following stimulation with the RANK ligand (RANKL). Cell adhesion signaling is also required for osteoclast differentiation from precursors. However, details of the mechanism by which cell adhesion signals induce osteoclast differentiation have not been fully elucidated. To investigate the participation of cell adhesion signaling in osteoclast differentiation, mouse bone marrow-derived macrophages (BMMs) were used as osteoclast precursors, and cultured on either plastic cell culture dishes (adherent condition) or the top surface of semisolid methylcellulose gel loaded in culture tubes (non-adherent condition). BMMs cultured under the adherent condition differentiated into osteoclasts in response to RANKL stimulation. However, under the non-adherent condition, the efficiency of osteoclast differentiation was markedly reduced even in the presence of RANKL. These BMMs retained macrophage characteristics including phagocytic function and gene expression profile. Lipopolysaccharide (LPS) and tumor necrosis factor -αTNF-α activated the NF-κB-mediated signaling pathways under both the adherent and non-adherent conditions, while RANKL activated the pathways only under the adherent condition. BMMs highly expressed RANK mRNA and protein under the adherent condition as compared to the non-adherent condition. Also, BMMs transferred from the adherent to non-adherent condition showed downregulated RANK expression within 24 hours. In contrast, transferring those from the non-adherent to adherent condition significantly increased the level of RANK expression. Moreover, interruption of cell adhesion signaling by echistatin, an RGD-containing disintegrin, decreased RANK expression in BMMs, while forced expression of either RANK or TNFR-associated factor 6 (TRAF6) in BMMs induced their differentiation into osteoclasts even under the non-adherent condition. These results suggest that cell adhesion signaling regulates RANK expression in osteoclast precursors. PMID:23139818

  6. Precursor events and self-organization leading to landslide triggering

    NASA Astrophysics Data System (ADS)

    Lehmann, Peter; Or, Dani

    2010-05-01

    Hillslopes often consist of many interacting soil and land-cover elements differing in hydraulic properties and mechanical strength. Intense rainfall events may result in heterogeneous distribution of hydrologic loading and internal weakening leading to local failure and stress redistribution to neighboring intact units. For certain spatial distributions of hydro-mechanical properties and timing of local failure events, ‘local' failure may propagate across the entire system culminating in landslide release (a ‘global' failure). Such ‘global' event is often preceded by numerous small precursor events (local failures) that theoretically may contain statistical information regarding imminent ‘global' failure and thus could provide certain early warning. We model the system and precursor events by combining concepts of Self-Organized Criticality (SOC) and Fiber Bundle Models (FBM) in a physically-based hydro-mechanical framework. The model consists of hexagonal soil columns connected by fiber bundles at their base and between adjacent elements. Fiber bundles represent mechanical bonds made of numerous connections (fibers) representing friction, roots, cementing agents, water bridges and alike that impart soil strength. Hydrological pathways and load distribution are simulated enabling updating of stresses on fiber bundles. When a bundle fails at element base, stress is redistributed to adjacent connected elements which may initiate a cascade of failures similar to other SOC models (e.g. sand pile model). Increasing hydro-mechanical loads during a rainfall event results in gradual small local fiber failures whose statistics follow a power-law with exponent depending on proximity to global failure. Such state-dependent precursor event statistics could provide a physical basis for field monitoring networks for early warning and hazard prediction. Additionally, the SOC concepts provide a simple framework for landslide susceptibility mapping in space and time and may provide input for subsequent debris flow routing models.

  7. Derivation of Glial Restricted Precursors from E13 mice

    PubMed Central

    Phillips, André W.; Falahati, Sina; DeSilva, Roshi; Shats, Irina; Marx, Joel; Arauz, Edwin; Kerr, Douglas A.; Rothstein, Jeffrey D.; Johnston, Michael V.; Fatemi, Ali

    2012-01-01

    This is a protocol for derivation of glial restricted precursor (GRP) cells from the spinal cord of E13 mouse fetuses. These cells are early precursors within the oligodendrocytic cell lineage. Recently, these cells have been studied as potential source for restorative therapies in white matter diseases. Periventricular leukomalacia (PVL) is the leading cause of non-genetic white matter disease in childhood and affects up to 50% of extremely premature infants. The data suggest a heightened susceptibility of the developing brain to hypoxia-ischemia, oxidative stress and excitotoxicity that selectively targets nascent white matter. Glial restricted precursors (GRP), oligodendrocyte progenitor cells (OPC) and immature oligodendrocytes (preOL) seem to be key players in the development of PVL and are the subject of continuing studies. Furthermore, previous studies have identified a subset of CNS tissue that has increased susceptibility to glutamate excitotoxicity as well as a developmental pattern to this susceptibility. Our laboratory is currently investigating the role of oligodendrocyte progenitors in PVL and use cells at the GRP stage of development. We utilize these derived GRP cells in several experimental paradigms to test their response to select stresses consistent with PVL. GRP cells can be manipulated in vitro into OPCs and preOL for transplantation experiments with mouse PVL models and in vitro models of PVL-like insults including hypoxia-ischemia. By using cultured cells and in vitro studies there would be reduced variability between experiments which facilitates interpretation of the data. Cultured cells also allows for enrichment of the GRP population while minimizing the impact of contaminating cells of non-GRP phenotype. PMID:22760029

  8. Observed and simulated precursors of Northern Hemisphere stratospheric vortex anomalies

    NASA Astrophysics Data System (ADS)

    Kolstad, Erik W.; Charlton-Perez, Andrew J.

    2010-05-01

    The strength and location of the Northern Hemisphere (NH) stratospheric polar vortex are linked to weather developments in the troposphere. Previous studies have shown that during the first 60 days after the onset of anomalous weak stratospheric vortex regimes in winter, the large-scale tropospheric circulation is nudged towards the negative phase of the Northern Annular Mode (NAM) and the North Atlantic Oscillation (NAO). A strong stratospheric vortex is associated with subsequent positive NAM/NAO conditions. The degree of usefulness of stratosphere-troposphere associations for predictive purposes depends on whether or not changes to the stratospheric vortex can be understood and predicted in advance. Recently, Garfinkel et al. proposed a new framework for identifying precursor patterns to major disturbances to the wintertime polar vortex. They suggested that these precursors could be understood by considering the relationship between the stationary wave pattern and the anomalous regional variability in the NH. Another important factor in understanding the stratosphere-troposphere links is the extent to which the inherent variability of the stratosphere in an atmospheric model influences its ability to simulate these links. Models differ greatly in their abilities to reproduce observed stratospheric variability, and these abilities appear not to depend simply upon the models' upper lid height or their stratospheric resolution. In this study, we examine the variability of the lower stratosphere in 300-year pre-industrial control integrations, with no volcanic or greenhouse gas forcing, from 13 CMIP3 coupled climate models. We show that: 1) Robust precursors to stratospheric variability events are evident across the multi-model ensemble, and 2) Comparisons of stratospheric variability across the ensemble enable us to develop tentative hypotheses about the role of the troposphere in determining the stratospheric vortex variability.

  9. Study of Ni-Zn Ferrite Prepared From Citrate Precursor

    NASA Astrophysics Data System (ADS)

    Sudheesh, V. D.; Vinesh, A.; Lakshmi, N.; Venugopalan, K.

    2011-07-01

    Ni0.5Zn0.5Fe2O4 prepared using citrate precursor method and calcined at different temperatures is studied using X-ray diffraction (XRD), Mössbauer spectroscopy and DC magnetization. Magnetization study shows that critical size of the sample is around 50 nm. Mössbauer studies confirm that there is no change in the cation distribution with calcining and also that a particle size distribution exists in samples calcined at higher temperatures. Thus the change in magnetic properties can be entirely attributed to structural parameters due to variation in size leading to different core-spin ratio, grain boundary effects etc.

  10. Studies of atherosclerosis determinants and precursors during childhood and adolescence*

    PubMed Central

    Tell, G. S.; Tuomilehto, J.; Epstein, F. H.; Strasser, T.

    1986-01-01

    At a Meeting of Investigators on Epidemiological Studies of Atherosclerosis Determinants and Precursors, which was held in Geneva on 7-9 November 1983, representatives from 26 countries reviewed the current status of epidemiological studies in this area. Particular interest was shown in the following determinants of cardiovascular disease: blood pressure, blood lipid levels, body weight, pathological studies, and tobacco use. Working papers on each determinant were prepared, and recommendations were made on areas for research, and on the need for prevention programmes and pathological studies. This article summarizes the work of the meeting. PMID:3490929

  11. Thin films by metal-organic precursor plasma spray

    SciTech Connect

    Schulz, Douglas L.; Sailer, Robert A.; Payne, Scott; Leach, James; Molz, Ronald J.

    2009-07-15

    While most plasma spray routes to coatings utilize solids as the precursor feedstock, metal-organic precursor plasma spray (MOPPS) is an area that the authors have investigated recently as a novel route to thin film materials. Very thin films are possible via MOPPS and the technology offers the possibility of forming graded structures by metering the liquid feed. The current work employs metal-organic compounds that are liquids at standard temperature-pressure conditions. In addition, these complexes contain chemical functionality that allows straightforward thermolytic transformation to targeted phases of interest. Toward that end, aluminum 3,5-heptanedionate (Al(hd){sub 3}), triethylsilane (HSi(C{sub 2}H{sub 5}){sub 3} or HSiEt{sub 3}), and titanium tetrakisdiethylamide (Ti(N(C{sub 2}H{sub 5}){sub 2}){sub 4} or Ti(NEt{sub 2}){sub 4}) were employed as precursors to aluminum oxide, silicon carbide, and titanium nitride, respectively. In all instances, the liquids contain metal-heteroatom bonds envisioned to provide atomic concentrations of the appropriate reagents at the film growth surface, thus promoting phase formation (e.g., Si-C bond in triethylsilane, Ti-N bond in titanium amide, etc.). Films were deposited using a Sulzer Metco TriplexPro-200 plasma spray system under various experimental conditions using design of experiment principles. Film compositions were analyzed by glazing incidence x-ray diffraction and elemental determination by x-ray spectroscopy. MOPPS films from HSiEt{sub 3} showed the formation of SiC phase but Al(hd){sub 3}-derived films were amorphous. The Ti(NEt{sub 2}){sub 4} precursor gave MOPPS films that appear to consist of nanosized splats of TiOCN with spheres of TiO{sub 2} anatase. While all films in this study suffered from poor adhesion, it is anticipated that the use of heated substrates will aid in the formation of dense, adherent films.

  12. Superhydrophobic Ceramic Coatings by Solution Precursor Plasma Spray

    NASA Astrophysics Data System (ADS)

    Cai, Yuxuan; Coyle, Thomas W.; Azimi, Gisele; Mostaghimi, Javad

    2016-04-01

    This work presents a novel coating technique to manufacture ceramic superhydrophobic coatings rapidly and economically. A rare earth oxide (REO) was selected as the coating material due to its hydrophobic nature, chemical inertness, high temperature stability, and good mechanical properties, and deposited on stainless steel substrates by solution precursor plasma spray (SPPS). The effects of various spraying conditions including standoff distance, torch power, number of torch passes, types of solvent and plasma velocity were investigated. The as-sprayed coating demonstrated a hierarchically structured surface topography, which closely resembles superhydrophobic surfaces found in nature. The water contact angle on the SPPS superhydrophobic coating was up to 65% higher than on smooth REO surfaces.

  13. Graphene nanoribbons synthesized from molecular precursor polymerization on Au(110)

    SciTech Connect

    Massimi, Lorenzo; Ourdjini, Oualid; Della Pia, Ada; Mariani, Carlo; Betti, Maria Grazia; Cavaliere, Emanuele; Gavioli, Luca

    2015-06-23

    A spectroscopic study of 10,10-dibromo-9,9 bianthracene (DBBA) molecules deposited on the Au(110) surface is presented, by means of ultraviolet and X-ray photoemission, and X-ray absorption spectroscopy. Through a thermally activated procedure, these molecular precursors polymerize and eventually form graphene nanoribbons (GNRs) with atomically controlled shape and width, very important building blocks for several technological applications. The GNRs observed by scanning tunneling microscopy (STM) appear as short segments on top of the gold surface reconstruction, pointing out the delicate balance among surface diffusion and surface corrugation in their synthesis on the Au(110) surface.

  14. Structural comparison of nickel electrodes and precursor phases

    NASA Technical Reports Server (NTRS)

    Cornilsen, Bahne C.; Shan, Xiaoyin; Loyselle, Patricia

    1989-01-01

    Researchers summarize previous Raman spectroscopic results and discuss important structural differences in the various phases of active mass and active mass precursors. Raman spectra provide unique signatures for these phases, and allow one to distinguish each phase, even when the compound is amorphous to x rays (i.e., does not scatter x rays because of a lack of order and/or small particle size). The structural changes incurred during formation, charge and discharge, cobalt addition, and aging are discussed. The oxidation states and dopant contents are explained in terms of the nonstoichiometric structures.

  15. Survey of volatile oxylipins and their biosynthetic precursors in bryophytes.

    PubMed

    Croisier, Emmanuel; Rempt, Martin; Pohnert, Georg

    2010-04-01

    Oxylipins are metabolites which are derived from the oxidative fragmentation of polyunsaturated fatty acids. These metabolites play central roles in plant hormonal regulation and defense. Here we survey the production of volatile oxylipins in bryophytes and report the production of a high structural variety of C5, C6, C8 and C9 volatiles of mosses. In liverworts and hornworts oxylipin production was not as pronounced as in the 23 screened mosses. A biosynthetic investigation revealed that both, C18 and C20 fatty acids serve as precursors for the volatile oxylipins that are mainly produced after mechanical wounding of the green tissue of mosses. PMID:20079505

  16. Precursors and pathways to adolescent prostitution in Taiwan.

    PubMed

    Hwang, Shu-Ling; Bedford, Olwen

    2003-05-01

    This paper identifies the major precursors and pathways to prostitution for contemporary Taiwanese girls and the socioeconomic and cultural changes that have facilitated the shift in pathways over the past 10 years. Special attention is paid to the case of Taiwanese aborigines, who have particularly suffered systemic disruption due to prostitution. Analysis of case files and interviews provide quantitative and qualitative data that highlight the role of filial piety and the shift from indenture to runaway as the major pathway in Taiwan. Discussion includes relation of these findings to juvenile entry into prostitution in other countries, directions for future research, and policy recommendations for Taiwan's government. PMID:12908127

  17. Review: R28 retinal precursor cells: The first 20 years

    PubMed Central

    2014-01-01

    The R28 retinal precursor cell line was established 20 years ago, originating from a postnatal day 6 rat retinal culture immortalized with the 12S E1A (NP-040507) gene of the adenovirus in a replication-incompetent viral vector. Since that time, R28 cells have been characterized and used for a variety of in vitro and in vivo studies of retinal cell behavior, including differentiation, neuroprotection, cytotoxicity, and light stimulation, as well as retinal gene expression and neuronal function. While no cell culture is equivalent to the intact eye, R28 cells continue to provide an important experimental system for the study of many retinal processes. PMID:24644404

  18. Beryllium-10 in Australasian tektites - Evidence for a sedimentary precursor

    NASA Technical Reports Server (NTRS)

    Pal, D. K.; Moniot, R. K.; Kruse, T. H.; Herzog, G. F.; Tuniz, C.

    1982-01-01

    Each of seven Australasian tektites contains about 100 micron atoms of beryllium-10 (half-life, 1.53 million years) per gram. Cosmic-ray bombardment of the australites cannot have produced the measured amounts of beryllium-10 either at the earth's surface or in space. The beryllium-10 contents of these australites are consistent with a sedimentary precursor that adsorbed from precipitation beryllium-10 produced in the atmosphere. The sediments must have spent several thousand years at the earth's surface within a few million years of the tektite-producing event.

  19. CVD Of Thin Films From Single Organometallic Precursors

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; Barron, Andrew R.; Power, Michael B.; Macinnes, Andrew N.; Jenkins, Phillip P.

    1996-01-01

    Method of forming thin inorganic films involves chemical vapor deposition (CVD) from single organometallic precursors. No toxic constituents, minimizes impurities, and yields films having substantially uniform crystal structure and composition. Especially suitable for depositing high-quality passivating or buffer layers of GaS on GaAs semiconductor substrates. Also applicable to formation of high-quality films for purposes other than buffering or passivation, and to different materials in which another element from same group in periodic table of elements substituted for all or portion of each element in GaS/GaAs system.

  20. Chondrule precursors and cooling paths: The sulfur evidence

    NASA Technical Reports Server (NTRS)

    Zanda, B.; Yu, Y.; Bourot-Denise, M.; Hewins, R. H.; Connolly, H. C., Jr.

    1994-01-01

    The behavior of moderately volatile elements (Na and S) is controversial but critical in understanding chondrule precursors and heating processes. Sulfide appeared to be present in most chondrules, but S should have been vaporized during chondrule formation. In fact, S is extensively redistributed in the course of metamorphism, and its abundance at the end of chondrule formation can only be inferred from the least equilibrated chondrites. Our study of 530 chondrules from Renazzo (CR2) and Semarkona (LL3.0) shows partial volatilization of S during chondrule formation and our melting experiments define conditions for total loss or partial retention of S.

  1. Gelcasting polymeric precursors for producing net-shaped graphites

    DOEpatents

    Klett, James W.; Janney, Mark A.

    2002-01-01

    The present invention discloses a method for molding complex and intricately shaped high density monolithic carbon, carbon-carbon, graphite, and thermoplastic composites using gelcasting technology. The method comprising a polymeric carbon precursor, a solvent, a dispersant, an anti-foaming agent, a monomer system, and an initiator system. The components are combined to form a suspension which is poured into a mold and heat-treated to form a thermoplastic part. The thermoplastic part can then be further densified and heat-treated to produce a high density carbon or graphite composite. The present invention also discloses the products derived from this method.

  2. Gelcasting polymeric precursors for producing net-shaped graphites

    DOEpatents

    Klett, James W.; Janney, Mark A.

    2005-02-15

    The present invention discloses a method for molding complex and intricately shaped high density monolithic carbon, carbon-carbon, graphite, and thermoplastic composites using gelcasting technology. The method comprising a polymeric carbon precursor, a solvent, a dispersant, an anti-foaming agent, a monomer system, and an initiator system. The components are combined to form a suspension which is poured into a mold and heat-treated to form a thermoplastic part. The thermoplastic part can then be further densified and heat-treated to produce a high density carbon or graphite composite. The present invention also discloses the products derived from this method.

  3. Graphene nanoribbons synthesized from molecular precursor polymerization on Au(110)

    NASA Astrophysics Data System (ADS)

    Massimi, Lorenzo; Ourdjini, Oualid; Cavaliere, Emanuele; Gavioli, Luca; Della Pia, Ada; Mariani, Carlo; Betti, Maria Grazia

    2015-06-01

    A spectroscopic study of 10,10-dibromo-9,9 bianthracene (DBBA) molecules deposited on the Au(110) surface is presented, by means of ultraviolet and X-ray photoemission, and X-ray absorption spectroscopy. Through a thermally activated procedure, these molecular precursors polymerize and eventually form graphene nanoribbons (GNRs) with atomically controlled shape and width, very important building blocks for several technological applications. The GNRs observed by scanning tunneling microscopy (STM) appear as short segments on top of the gold surface reconstruction, pointing out the delicate balance among surface diffusion and surface corrugation in their synthesis on the Au(110) surface.

  4. Imaging Transition Zone Thickness Beneath South America from SS Precursors

    NASA Astrophysics Data System (ADS)

    Schmerr, N.; Garnero, E.

    2006-12-01

    We image detailed upper mantle discontinuity structure beneath a number of geologically active regions, including the South American subduction zone, the Scotia plate subduction zone, and several volcanic hotspots (e.g., the Galapagos Islands), in a region ~10,000 km by 10,000 km wide, spanning 70° S to 20° N and 20° W to 110° W. Precursors to the seismic phase SS are analyzed, which form as a result of underside reflections off seismic discontinuities beneath the midpoint of the SS path and are highly sensitive to discontinuity depth and sharpness. Our SS dataset consists of over 15,000 high-quality transverse component broadband displacement seismograms collected from the Incorporated Research Institutions for Seismology (IRIS), the Canadian National Seismic Network (CNSN), as well as data from EarthScope seismic stations, and from the Canadian Northwest Experiment (CANOE) temporary broadband array deployment. This dataset densely samples several regions in our study area and significantly improves the sampling for this area compared to previous precursor studies. Data with common central SS bouncepoints are stacked to enhance precursory phases. Solution discontinuity structure depends on a number of factors, including dominant seismic period, crustal correction, signal-to-noise ratio threshold, and tomography model used for mantle heterogeneity correction. We exclude precursor data predicted to interfere with other seismic phases, such as topside reflections (e.g., s670sS), which have been demonstrated to contaminate final stacks. Solution transition zone thickness is at least 20 km thicker than global average estimates of 242 km along the northwestern portion of the South American subduction complex (Peru, Ecuador, and Columbia); this thickening extends 1000-1500 km to the east beneath the continent, but does not appear to continue south of -20° latitude along the convergent margin. A minimum of 10 km of thickening is imaged to the west of the Scotia subduction zone, consistent with colder material reaching the transition zone, and 5-10 km of thinning off the southern coast of Brazil, possibly associated with the Martin/Trinidade and/or St. Helena hotspots. Our results are consistent with tectonics at much smaller scales and hence support the SS precursor approach as a valuable probe of transition zone structure and processes when abundant broadband data are available.

  5. Pillarlike Crystals of Pentacene Prepared from Soluble Precursor

    NASA Astrophysics Data System (ADS)

    Murai, Yuki; Misaki, Masahiro; Ishida, Kenji; Ueda, Yasukiyo

    2011-12-01

    Pillarlike crystals of pentacene were fabricated by heat treatment of 13,6-N-sulfinylacetamidopentacene (SAP) thin films prepared from a soluble precursor. As-spun SAP films were composed of a continuous amorphous layer. SAP molecules were converted to pentacene by an elimination reaction by heat treatment at 110 °C. When the SAP film was heat-treated at 170 °C, the pentacene molecules formed pillarlike crystals of uniform height, wherein they took an edge-on orientation with respect to the substrate.

  6. Polymer precursors for SiC ceramic materials

    NASA Technical Reports Server (NTRS)

    Litt, Morton H.

    1986-01-01

    Work on precursor polymers to SiC was performed, concentrating on polymers made from decamethyl cyclohexasilyene units. The initial approach was to synthesize mixed diphenyl decamethyl cyclohexasilane, dephenylate, and polymerize. This produced polymers which had yields of up to 50 percent SiC. (Theoretical yield is 75 percent). The present approach is to make the polymer through the intermediate trans-1,4-diphenyl decamethyl cyclohexasilane. This should produce a crystalline polymer and high strength fibers. These will be thermally decomposed to SiC fibers. This requires new chemistry which is currently being studied.

  7. Strain-induced dimensionality crossover of precursor modulations in Ni{sub 2}MnGa

    SciTech Connect

    Nie, Zhihua E-mail: ydwang@neu.edu.cn; Wang, Yandong E-mail: ydwang@neu.edu.cn; Shang, Shunli; Wang, Yi; Liu, Zi-Kui; Zeng, Qiaoshi; Ren, Yang; Liu, Dongmei; Yang, Wenge

    2015-01-12

    Precursor modulations often occur in functional materials like magnetic shape memory alloys, ferroelectrics, and superconductors. In this letter, we have revealed the underlying mechanism of the precursor modulations in ferromagnetic shape memory alloys Ni{sub 2}MnGa by combining synchrotron-based x-ray diffraction experiments and first-principles phonon calculations. We discovered the precursor modulations along [011] direction can be eliminated with [001] uniaxial loading, while the precursor modulations or premartensite can be totally suppressed by hydrostatic pressure condition. The TA{sub 2} phonon anomaly is sensitive to stress induced lattice strain, and the entire TA{sub 2} branch is stabilized along the directions where precursor modulations are eliminated by external stress. Our discovery bridges precursor modulations and phonon anomalies, and sheds light on the microscopic mechanism of the two-step superelasticity in precursor martensite.

  8. Strain-induced dimensionality crossover of precursor modulations in Ni2MnGa

    SciTech Connect

    Nie, Zhihua; Wang, Yandong; Shang, Shunli; Zeng, Qiaoshi; Ren, Yang; Liu, Dongmei; Yang, Wenge; Wang, Yi; Liu, Zi-Kui

    2015-01-01

    Precursor modulations often occur in functional materials like magnetic shape memory alloys, ferroelectrics, and superconductors. In this letter, we have revealed the underlying mechanism of the precursor modulations in ferromagnetic shape memory alloys Ni2MnGa by combining synchrotron-based x-ray diffraction experiments and first-principles phonon calculations. We discovered the precursor modulations along [011] direction can be eliminated with [001] uniaxial loading, while the precursor modulations or premartensite can be totally suppressed by hydrostatic pressure condition. The TA2 phonon anomaly is sensitive to stress induced lattice strain, and the entire TA2 branch is stabilized along the directions where precursor modulations are eliminated by external stress. Our discovery bridges precursor modulations and phonon anomalies, and sheds light on the microscopic mechanism of the two-step superelasticity in precursor martensite.

  9. Methods of making copper selenium precursor compositions with a targeted copper selenide content and precursor compositions and thin films resulting therefrom

    DOEpatents

    Curtis, Calvin J.; Miedaner, Alexander; van Hest, Marinus Franciscus Antonius Maria; Ginley, David S.; Leisch, Jennifer; Taylor, Matthew; Stanbery, Billy J.

    2011-09-20

    Precursor compositions containing copper and selenium suitable for deposition on a substrate to form thin films suitable for semi-conductor applications. Methods of forming the precursor compositions using primary amine solvents and methods of forming the thin films wherein the selection of temperature and duration of heating controls the formation of a targeted species of copper selenide.

  10. Nucleocytoplasmic transport and processing of small nuclear RNA precursors.

    PubMed Central

    Neuman de Vegvar, H E; Dahlberg, J E

    1990-01-01

    We have analyzed the structures and locations of small nuclear RNA (snRNA) precursors at various stages in their synthesis and maturation. In the nuclei of pulse-labeled Xenopus laevis oocytes, we detected snRNAs that were longer than their mature forms at their 3' ends by up to 10 nucleotides. Analysis of the 5' caps of these RNAs and pulse-chase experiments showed that these nuclear snRNAs were precursors of the cytoplasmic pre-snRNAs that have been observed in the past. Synthesis of pre-snRNAs was not abolished by wheat germ agglutinin, which inhibits export of the pre-snRNAs from the nucleus, indicating that synthesis of these RNAs is not obligatorily coupled to their export. Newly synthesized U1 RNAs could be exported from the nucleus regardless of the length of the 3' extension, but pre-U1 RNAs that were elongated at their 3' ends by more than about 10 nucleotides were poor substrates for trimming in the cytoplasm. The structure at the 3' end was critical for subsequent transport of the RNA back to the nucleus. This requirement ensures that truncated and incompletely processed U1 RNAs are excluded from the nucleus. Images PMID:2355910

  11. Regenerative Translation of Human Blood-Vessel-Derived MSC Precursors

    PubMed Central

    Chen, William C. W.; Péault, Bruno; Huard, Johnny

    2015-01-01

    Mesenchymal stem/stromal cells (MSCs) represent a promising adult progenitor cell source for tissue repair and regeneration. Their mysterious identity in situ has gradually been unveiled by the accumulating evidence indicating an association between adult multipotent stem/progenitor cells and vascular/perivascular niches. Using immunohistochemistry and fluorescence-activated cell sorting, we and other groups have prospectively identified and purified subpopulations of multipotent precursor cells associated with the blood vessels within multiple human organs. The three precursor subsets, myogenic endothelial cells (MECs), pericytes (PCs), and adventitial cells (ACs), are located, respectively, in the three structural tiers of typical blood vessels: intima, media, and adventitia. MECs, PCs, and ACs have been extensively characterized in prior studies and are currently under investigation for their therapeutic potentials in preclinical animal models. In this review, we will briefly discuss the identification, isolation, and characterization of these human blood-vessel-derived stem cells (hBVSCs) and summarize the current status of regenerative applications of hBVSC subsets. PMID:26273304

  12. Regenerative Translation of Human Blood-Vessel-Derived MSC Precursors.

    PubMed

    Chen, William C W; Péault, Bruno; Huard, Johnny

    2015-01-01

    Mesenchymal stem/stromal cells (MSCs) represent a promising adult progenitor cell source for tissue repair and regeneration. Their mysterious identity in situ has gradually been unveiled by the accumulating evidence indicating an association between adult multipotent stem/progenitor cells and vascular/perivascular niches. Using immunohistochemistry and fluorescence-activated cell sorting, we and other groups have prospectively identified and purified subpopulations of multipotent precursor cells associated with the blood vessels within multiple human organs. The three precursor subsets, myogenic endothelial cells (MECs), pericytes (PCs), and adventitial cells (ACs), are located, respectively, in the three structural tiers of typical blood vessels: intima, media, and adventitia. MECs, PCs, and ACs have been extensively characterized in prior studies and are currently under investigation for their therapeutic potentials in preclinical animal models. In this review, we will briefly discuss the identification, isolation, and characterization of these human blood-vessel-derived stem cells (hBVSCs) and summarize the current status of regenerative applications of hBVSC subsets. PMID:26273304

  13. Soot precursor measurements in benzene and hexane diffusion flames

    SciTech Connect

    Kobayashi, Y.; Furuhata, T.; Amagai, K.; Arai, M.

    2008-08-15

    To clarify the mechanism of soot formation in diffusion flames of liquid fuels, measurements of soot and its precursors were carried out. Sooting diffusion flames formed by a small pool combustion equipment system were used for this purpose. Benzene and hexane were used as typical aromatic and paraffin fuels. A laser-induced fluorescence (LIF) method was used to obtain spatial distributions of polycyclic aromatic hydrocarbons (PAHs), which are considered as soot particles. Spatial distributions of soot in test flames were measured by a laser-induced incandescence (LII) method. Soot diameter was estimated from the temporal change of LII intensity. A region of transition from PAHs to soot was defined from the results of LIF and LII. Flame temperatures, PAH species, and soot diameters in this transition region were investigated for both benzene and hexane flames. The results show that though the flame structures of benzene and hexane were different, the temperature in the PAHs-soot transition region of the benzene flame was similar to that of the hexane flame. Furthermore, the relationship between the PAH concentrations measured by gas chromatography in both flames and the PAH distributions obtained from LIF are discussed. It was found that PAHs with smaller molecular mass, such as benzene and toluene, remained in both the PAHs-soot transition and sooting regions, and it is thought that molecules heavier than pyrene are the leading candidates for soot precursor formation. (author)

  14. Follicular Dendritic Cells Emerge from Ubiquitous Perivascular Precursors

    PubMed Central

    Krautler, Nike Julia; Kana, Veronika; Kranich, Jan; Tian, Yinghua; Perera, Dushan; Lemm, Doreen; Schwarz, Petra; Armulik, Annika; Browning, Jeffrey L.; Tallquist, Michelle; Buch, Thorsten; Oliveira-Martins, José B.; Zhu, Caihong; Hermann, Mario; Wagner, Ulrich; Brink, Robert; Heikenwalder, Mathias; Aguzzi, Adriano

    2013-01-01

    Summary The differentiation of follicular dendritic cells (FDC) is essential to the remarkable microanatomic plasticity of lymphoid follicles. Here we show that FDC arise from ubiquitous perivascular precursors (preFDC) expressing platelet-derived growth factor receptor β (PDGFRβ). PDGFRβ-Cre-driven reporter gene recombination resulted in FDC labeling, whereas conditional ablation of PDGFRβ+-derived cells abolished FDC, indicating that FDC originate from PDGFRβ+ cells. Lymphotoxin-α-overexpressing prion protein (PrP)+ kidneys developed PrP+ FDC after transplantation into PrP mice, confirming that preFDC exist outside lymphoid organs. Adipose tissue-derived PDGFRβ+ stromal-vascular cells responded to FDC maturation factors and, when transplanted into lymphotoxin β receptor (LTβR) kidney capsules, differentiated into Mfge8+CD21/35+ FcγRIIβ+PrP+ FDC capable of trapping immune complexes and recruiting B cells. Spleens of lymphocyte-deficient mice contained perivascular PDGFRβ+ FDC precursors whose expansion required both lymphoid tissue inducer (LTi) cells and lymphotoxin. The ubiquity of preFDC and their strategic location at blood vessels may explain the de novo generation of organized lymphoid tissue at sites of lymphocytic inflammation. PMID:22770220

  15. An Accident Precursor Analysis Process Tailored for NASA Space Systems

    NASA Technical Reports Server (NTRS)

    Groen, Frank; Stamatelatos, Michael; Dezfuli, Homayoon; Maggio, Gaspare

    2010-01-01

    Accident Precursor Analysis (APA) serves as the bridge between existing risk modeling activities, which are often based on historical or generic failure statistics, and system anomalies, which provide crucial information about the failure mechanisms that are actually operative in the system and which may differ in frequency or type from those in the various models. These discrepancies between the models (perceived risk) and the system (actual risk) provide the leading indication of an underappreciated risk. This paper presents an APA process developed specifically for NASA Earth-to-Orbit space systems. The purpose of the process is to identify and characterize potential sources of system risk as evidenced by anomalous events which, although not necessarily presenting an immediate safety impact, may indicate that an unknown or insufficiently understood risk-significant condition exists in the system. Such anomalous events are considered accident precursors because they signal the potential for severe consequences that may occur in the future, due to causes that are discernible from their occurrence today. Their early identification allows them to be integrated into the overall system risk model used to intbrm decisions relating to safety.

  16. Compartmentation of guanine nucleotide precursors for DNA synthesis.

    PubMed Central

    Nguyen, B T; Sadée, W

    1986-01-01

    We have studied the kinetics of guanine incorporation into DNA in mouse T-lymphoma (S-49) mutant cells [PNPase (purine-nucleoside phosphorylase)- and HGPRTase (hypoxanthine: guanine phosphoribosyltransferase)-deficient] that are incapable of converting dGuo (deoxyguanosine) to Gua (guanine) ribonucleotides. Of the two possible pathways for an exogenous guanine source to reach DNA, firstly: dGuo----dGMP----dGDP----dGTP and secondly: Gua----GMP----GDP----dGDP----dGTP only the second pathway was found to be functional in providing guanine for DNA replication, although deoxyguanosine readily produced toxic cellular dGTP levels via the first pathway. The functional guanine-nucleotide-precursor pools for DNA are rather small; further, the depletion of the small GMP pool, but not that of GDP, GTP and dGTP, correlated well with the inhibition of DNA synthesis by mycophenolic acid, an IMP dehydrogenase inhibitor. These results support the hypothesis that guanine-nucleotide incorporation into DNA is highly compartmentalized and that a small functional guanine-nucleotide pool, e.g., the GMP pool, may serve a crucial role in limiting the availability of DNA precursor substrate. PMID:2424429

  17. MAGNETIC AND DENSITY SPIKES IN COSMIC-RAY SHOCK PRECURSORS

    SciTech Connect

    Malkov, M. A.; Diamond, P. H.; Sagdeev, R. Z.

    2012-04-01

    In shock precursors populated by accelerated cosmic rays (CRs), the CR return current instability is believed to significantly enhance the pre-shock perturbations of magnetic field. We have obtained fully nonlinear exact ideal MHD solutions supported by the CR return current. The solutions occur as localized spikes of circularly polarized Alfven envelopes (solitons or breathers). As the conventional (undriven) solitons, the obtained magnetic spikes propagate at a speed C proportional to their amplitude, C=C{sub A}B{sub max}/{radical}2B{sub 0}. The sufficiently strong solitons run thus ahead of the main shock and stand in the precursor, being supported by the return current. This property of the nonlinear solutions is strikingly different from the linear theory that predicts non-propagating (that is, convected downstream) circularly polarized waves. The nonlinear solutions may come either in isolated pulses (solitons) or in soliton-trains (cnoidal waves). The morphological similarity of such quasi-periodic soliton chains with recently observed X-ray stripes in the Tycho supernova remnant (SNR) is briefly discussed. The magnetic field amplification determined by the suggested saturation process is obtained as a function of decreasing SNR blast wave velocity during its evolution from the ejecta dominated to the Sedov-Taylor stage.

  18. Novel drug delivery strategies for porphyrins and porphyrin precursors

    NASA Astrophysics Data System (ADS)

    Morrow, D. I. J.; Donnelly, R. F.

    2009-06-01

    superficial lesions, such as actinic keratosis. In addition, photodynamic antimicrobial chemotherapy (PACT) is attracting increasing interest for the treatment of infection. However, delivery strategies for topical PDT and PACT are still based on application of rather simplistic cream and solution formulations, with little consideration given to thermodynamics, targeting or the physicochemical properties of the active agent. Purpose-designed dosage forms for topical delivery of aminolevulinic acid or its esters include creams containing penetration enhancers and/or iron chelators, pressure sensitive patches and bioadhesive patches. Such systems aim to enhance drug delivery across the stratum corneum and keratinised debris overlying neoplastic lesions and improve subsequent protoporphyrin IX (PpIX) production. The alternative to using porphyrin precursors is the use of pre-formed photosensitisers. However, owing to their relatively high molecular weights, conventional topical application is not appropriate. Innovative strategies, such as the use of needle-free injections and microneedle arrays, bypass the stratum corneum, enabling rapid and targeted delivery not only porphyrin precursors but also pre-formed photosensitisers. This presentation will review drug delivery work published to date in the fields of PDT and PACT. In addition, the benefits of employing the latest advances in pharmaceutical technology will be highlighted.

  19. Radon anomaly in soil gas as an earthquake precursor.

    PubMed

    Miklavci?, I; Radoli?, V; Vukovi?, B; Poje, M; Varga, M; Stani?, D; Planini?, J

    2008-10-01

    The mechanical processes of earthquake preparation are always accompanied by deformations; afterwards, the complex short- or long-term precursory phenomena can appear. Anomalies of radon concentrations in soil gas are registered a few weeks or months before many earthquakes. Radon concentrations in soil gas were continuously measured by the LR-115 nuclear track detectors at site A (Osijek) during a 4-year period, as well as by the Barasol semiconductor detector at site B (Kasina) during 2 years. We investigated the influence of the meteorological parameters on the temporal radon variations, and we determined the equation of the multiple regression that enabled the reduction (deconvolution) of the radon variation caused by the barometric pressure, rainfall and temperature. The pre-earthquake radon anomalies at site A indicated 46% of the seismic events, on criterion M>or=3, R<200 km, and 21% at site B. Empirical equations between earthquake magnitude, epicenter distance and precursor time enabled estimation or prediction of an earthquake that will rise at the epicenter distance R from the monitoring site in expecting precursor time T. PMID:18424052

  20. Neural precursors derived from human embryonic stem cells.

    PubMed

    Peng, Hongmei; Chen, Gui'an

    2005-06-01

    Human embryonic stem (hES) cells provide a promising supply of specific cell types for transplantation therapy. We presented here the method to induce differentiation of purified neural precursors from hES cells. hES cells (Line PKU-1 and Line PKU-2) were cultured in suspension in bacteriological Petri dishes, which differentiated into cystic embryoid bodies (EBs). The EBs were then cultured in N2 medium containing bFGF in poly-L-lysine-coated tissue culture dishes for two weeks. The central, small cells with 2-3 short processes of the spreading outgrowth were isolated mechanically and replated. The resulting neurospheres were cultured in suspension for 10 days, then dissociated into single cell suspension with a Pasteur pipette and plated. Cells grew vigorously in an attached way and were passed every 4-5 days. Almost all the cells were proved nestin positive by immunostaining. Following withdrawal of bFGF, they differentiated into neurons expressing beta-tubulin isotype(III), GABA, serotonin and synaptophysin. Through induction of PDGF-AA, they differentiated into astrocytes expressing GFAP and oligodendrocytes expressing O4. The results showed that hES cells can differentiate into typical neural precursors expressing the specific marker nestin and capable of generating all three cell types of the central nervous system (CNS) in vitro. PMID:16092763

  1. Methods of forming single source precursors, methods of forming polymeric single source precursors, and single source precursors formed by such methods

    DOEpatents

    Fox, Robert V.; Rodriguez, Rene G.; Pak, Joshua J.; Sun, Chivin; Margulieux, Kelsey R.; Holland, Andrew W.

    2014-09-09

    Methods of forming single source precursors (SSPs) include forming intermediate products having the empirical formula 1/2{L.sub.2N(.mu.-X).sub.2M'X.sub.2}.sub.2, and reacting MER with the intermediate products to form SSPs of the formula L.sub.2N(.mu.-ER).sub.2M'(ER).sub.2, wherein L is a Lewis base, M is a Group IA atom, N is a Group IB atom, M' is a Group IIIB atom, each E is a Group VIB atom, each X is a Group VIIA atom or a nitrate group, and each R group is an alkyl, aryl, vinyl, (per)fluoro alkyl, (per)fluoro aryl, silane, or carbamato group. Methods of forming polymeric or copolymeric SSPs include reacting at least one of HE.sup.1R.sup.1E.sup.1H and MER with one or more substances having the empirical formula L.sub.2N(.mu.-ER).sub.2M'(ER).sub.2 or L.sub.2N(.mu.-X).sub.2M'(X).sub.2 to form a polymeric or copolymeric SSP. New SSPs and intermediate products are formed by such methods.

  2. Methods of forming single source precursors, methods of forming polymeric single source precursors, and single source precursors formed by such methods

    DOEpatents

    Fox, Robert V.; Rodriguez, Rene G.; Pak, Joshua J.; Sun, Chivin; Margulieux, Kelsey R.; Holland, Andrew W.

    2016-04-19

    Methods of forming single source precursors (SSPs) include forming intermediate products having the empirical formula 1/2{L.sub.2N(.mu.-X).sub.2M'X.sub.2}.sub.2, and reacting MER with the intermediate products to form SSPs of the formula L.sub.2N(.mu.-ER).sub.2M'(ER).sub.2, wherein L is a Lewis base, M is a Group IA atom, N is a Group IB atom, M' is a Group IIIB atom, each E is a Group VIB atom, each X is a Group VIIA atom or a nitrate group, and each R group is an alkyl, aryl, vinyl, (per)fluoro alkyl, (per)fluoro aryl, silane, or carbamato group. Methods of forming polymeric or copolymeric SSPs include reacting at least one of HE.sup.1R.sup.1E.sup.1H and MER with one or more substances having the empirical formula L.sub.2N(.mu.-ER).sub.2M'(ER).sub.2 or L.sub.2N(.mu.-X).sub.2M'(X).sub.2 to form a polymeric or copolymeric SSP. New SSPs and intermediate products are formed by such methods.

  3. Methods of forming single source precursors, methods of forming polymeric single source precursors, and single source precursors and intermediate products formed by such methods

    DOEpatents

    Fox, Robert V.; Rodriguez, Rene G.; Pak, Joshua J.; Sun, Chivin; Margulieux, Kelsey R.; Holland, Andrew W.

    2012-12-04

    Methods of forming single source precursors (SSPs) include forming intermediate products having the empirical formula 1/2{L.sub.2N(.mu.-X).sub.2M'X.sub.2}.sub.2, and reacting MER with the intermediate products to form SSPs of the formula L.sub.2N(.mu.-ER).sub.2M'(ER).sub.2, wherein L is a Lewis base, M is a Group IA atom, N is a Group IB atom, M' is a Group IIIB atom, each E is a Group VIB atom, each X is a Group VIIA atom or a nitrate group, and each R group is an alkyl, aryl, vinyl, (per)fluoro alkyl, (per)fluoro aryl, silane, or carbamato group. Methods of forming polymeric or copolymeric SSPs include reacting at least one of HE.sup.1R.sup.1E.sup.1H and MER with one or more substances having the empirical formula L.sub.2N(.mu.-ER).sub.2M'(ER).sub.2 or L.sub.2N(.mu.-X).sub.2M'(X).sub.2 to form a polymeric or copolymeric SSP. New SSPs and intermediate products are formed by such methods.

  4. Characterization and fate of N-nitrosodimethylamine precursors in municipal wastewater treatment plants.

    PubMed

    Mitch, William A; Sedlak, David L

    2004-03-01

    The potent carcinogen, N-nitrosodimethylamine (NDMA), is produced during disinfection of municipal wastewater effluent from the reaction of monochloramine and organic nitrogen-containing precursors. To delineate the sources and fate of NDMA precursors during municipal wastewater treatment, NDMA formation was measured after extended chloramination of both model precursors and samples from conventional and advanced wastewater treatment plants. Of the model precursors, only dimethylamine, tertiary amines with dimethylamine functional groups, and dimethylamides formed significant NDMA concentrations upon chloramination. In samples from municipal wastewater treatment plants, dissolved NDMA precursors always were present in primary and secondary effluents. Biological treatment effectively removed the known NDMA precursor dimethylamine, lowering its concentration to levels that could not produce significant quantities of NDMA upon chlorine disinfection. However, biological treatment was less effective at removing other dissolved NDMA precursors, even after extended biological treatment. Significant concentrations of particle-associated NDMA precursors only were detected in secondary effluent at treatment plants that recycled water from sludge thickening operations in which dimethylamine-based synthetic polymers were used. Effective strategies for the prevention of NDMA formation during wastewater chlorination include ammonia removal by nitrification to preclude chloramine formation during chlorine disinfection, elimination of dimethylamine-based polymers, and use of filtration and reverse osmosis to remove particle-associated precursors and dissolved precursors, respectively. PMID:15046346

  5. Differential processing of amyloid-beta precursor protein directs human embryonic stem cell proliferation and differentiation into neuronal precursor cells.

    PubMed

    Porayette, Prashob; Gallego, Miguel J; Kaltcheva, Maria M; Bowen, Richard L; Vadakkadath Meethal, Sivan; Atwood, Craig S

    2009-08-28

    The amyloid-beta precursor protein (AbetaPP) is a ubiquitously expressed transmembrane protein whose cleavage product, the amyloid-beta (Abeta) protein, is deposited in amyloid plaques in neurodegenerative conditions such as Alzheimer disease, Down syndrome, and head injury. We recently reported that this protein, normally associated with neurodegenerative conditions, is expressed by human embryonic stem cells (hESCs). We now report that the differential processing of AbetaPP via secretase enzymes regulates the proliferation and differentiation of hESCs. hESCs endogenously produce amyloid-beta, which when added exogenously in soluble and fibrillar forms but not oligomeric forms markedly increased hESC proliferation. The inhibition of AbetaPP cleavage by beta-secretase inhibitors significantly suppressed hESC proliferation and promoted nestin expression, an early marker of neural precursor cell (NPC) formation. The induction of NPC differentiation via the non-amyloidogenic pathway was confirmed by the addition of secreted AbetaPPalpha, which suppressed hESC proliferation and promoted the formation of NPCs. Together these data suggest that differential processing of AbetaPP is normally required for embryonic neurogenesis. PMID:19542221

  6. Consideration of formation process for the nuclei on precursor

    NASA Astrophysics Data System (ADS)

    Nagata, J.; Okamoto, M.

    2003-12-01

    The very isotropic microwave background and the Hubble expansion indicate that the universe has evolved from an earlier state of high temperature and density that can be reasonably well described by Friedman-Lemaitre-Robertson-Walker cosmological models. The nuclear evolution of non-degenerate matter expanding from very high temperature was studied in detail for various values of the expansion rate and of the proton-neutron abundance difference and baryon density[1,2,3]. In this calculation, many nuclear reactions were included, and its results suggested important reaction process for the evolution of nuclear abundances. 3He and 4He are very important elements in these nuclear reactions as the primordial nucleosynthesis. Microscopic study for few body system is one main topic in nuclear theoretical physics. In this field, very accurate calculations are available by using the Faddeev equations[4]. Recently, many data for pd, p-3He and d-3He have been obtained including polarized observables. Model calculations for systems including 3He and 4He (for example, d + 3He -> p + 4He) are carried out using the Faddeev equations based on the meson exchange models[4]. This model reproduces well the empirical phase shifts which are determined by so-called phase-shift analyses using all of available scattering data measured at various laboratories around the world[5,6,7]. Constructions of models for the nuclear reactions including 3He and 4He will give important information for calculations of the primordial nucleosynthesis after big-ban. The calculations are carried out until the sum of the abundances at each mass number ceases to change. Various different set of initial conditions for the baryon mass density, the expansion rate and the neutron-proton ratio are used. Dusts kept in precursor asteroid nebular form precursor asteroid, then, formations of planet start [8]. Possible values of parameters in the initial conditions for theoretical calculations will be searched considering an information from precursor asteroid References: {[1]} R. V. Wagoner, W. A. Fowler and F. Hoyle (1967), Astrophys. J. 148, 3. {[2]} R. V. Wagoner. (1969), Astrophys. J. 162, 247. [3] R. V. Wagoner (1973), Astrophys. J. 179, 343. [4] For example, S. Gojyuki and S. Oryu (2003), Mod. Phys. Lett. A18, 302. [5] Y. Yoshino, V. Limkaisang, J. Nagata, H. Yoshino and M. Matsuda (2000), Prog. Theor. Phys. 103, 107. [6] H. Yoshino, J. Nagata, V. Limkaisang, Y. Yoshino, M. Matsuda (2001), Nucl. Phys. A684, 615c. [7] H. Yoshino, H. Kazuo, M. Matsuda, J. Nagata, (2003), Mod. Phys. Lett. A18, 444. [8] Hayashi, C. et. al., 1985, Protostars and Planets, Univ. of Arizona Press, pp. 1100.

  7. Activated microporous materials through polymerization of microemulsion precursors

    NASA Astrophysics Data System (ADS)

    Venkatesan, Arunkumar

    Microemulsions have been well studied for their unique characteristics. They are isotropic, thermodynamically stable and microstructured mixtures of oil and water stabilized by one or more surfactant species. They are formed spontaneously and are thermodynamically stable. Microemulsion precursors can be polymerized to make microporous solids with controlled pore structure and sizes. These polymeric solids have been studied extensively in the past. Although the fundamental properties of the microporous solids have been studied in depth, the development of specific applications that will utilize the unique properties of these solids has not been exhaustively researched. The current work establishes the feasibility of making activated microporous solids from microemulsion precursors, by the use of a ligand that chelates metals and also attaches itself to the polymer monolith. It also uses a novel 'in-situ' incorporation by combining the formulation and incorporation steps into one. The research objectives are, to formulate a microemulsion system that can yield useful microporous solids upon polymerization and activation, to characterize these solids using existing techniques available for analysis of similar microporous solids, to identify and understand the effect of the variables in the system and to study the influence of these variables on the performance characteristics of this material. Characterization techniques like Differential Scanning Calorimetry, Thermogravimetric Analysis and Scanning Electron Microscopy were used. A hydroxyethylmethylmethacrylate/methylmethacrylate/aqueous phase containing 10% SDS' system was chosen as the precursor microemulsion and the corresponding microporous solids were made. A metal chelating ligand, Congo Red, was incorporated onto the microporous polymer using NaOH as a binding agent. The ability of the resultant 'activated' microporous solid to remove metal ions from solution, was evaluated. The metal ion chosen was chromium and the influence of variables such as NaOH loading, Congo Red loading, Cross linker content etc. were studied. It was found that the microporous solids were effective in removing chromium from solution. They outperformed similar polymeric solids with ligands (reported in literature) in chromium removal. A removal of about 1500 micro moles of chromium ions per gram of dry polymer from a solution of 5 mMol/L initial concentration of chromium was observed. This is much more than the removal of 340 micro moles/gram of dry polymer reported in literature for comparable non-microporous systems.

  8. Instellar Exploration: Propulsion Options for Precursors and Beyond

    NASA Technical Reports Server (NTRS)

    Johnson, Charles Les; Leifer, Stephanie

    1999-01-01

    NASA is considering a mission to explore near-interstellar space early in the next decade as the first step toward a vigorous interstellar exploration program. A key enabling technology for such an ambitious science and exploration effort is the development of propulsion systems capable of providing fast trip times; mission duration should not exceed the professional lifetime of the investigative team. Advanced propulsion technologies that might support an interstellar precursor mission early in the next century include some combination of solar sails, nuclear electric propulsion systems, and aerogravity assists. Follow-on missions to far beyond the heliopause will require the development of propulsion technologies that are only at the conceptual stage today. These include 1) matter-antimatter annihilation, 2) beamed-energy sails, and 3) fusion systems. For years, the scientific community has been interested in the development of solar sail technology to support exploration of the inner and outer planets. Progress in thin-film technology and the development of technologies that may enable the remote assembly of large sails in space are only now maturing to the point where ambitious interstellar precursor missions can be considered. Electric propulsion is now being demonstrated for planetary exploration by the Deep Space 1 mission. The primary issues for it's adaptation to interstellar precursor applications include the nuclear reactor that would be required and the engine lifetime. For further term interstellar missions, matter-antimatter annihilation propulsion system concepts have the highest energy density of any propulsion systems using onboard propellants. However, there are numerous challenges to production and storage of antimatter that must be overcome before it can be seriously considered for interstellar flight. Off-board energy systems (laser sails) are candidates for long-distance interstellar flight but development of component technologies and necessary infrastructure have not begun.. Fusion propulsion has been studied extensively. However, fusion technology is still considered immature, even after many decades of well-funded research. Furthermore, fusion alone does not offer high enough energy density to make it a viable candidate for interstellar propulsion unless propellant can be collected in situ, as was considered by R. Bussard for his interstellar ramjet concept. The current research in investigating these propulsion systems will be described, and the range of application of each technology will be explored.

  9. Superhydrophobic Ceramic Coatings by Solution Precursor Plasma Spray.

    PubMed

    Cai, Yuxuan; Coyle, Thomas W; Azimi, Gisele; Mostaghimi, Javad

    2016-01-01

    This work presents a novel coating technique to manufacture ceramic superhydrophobic coatings rapidly and economically. A rare earth oxide (REO) was selected as the coating material due to its hydrophobic nature, chemical inertness, high temperature stability, and good mechanical properties, and deposited on stainless steel substrates by solution precursor plasma spray (SPPS). The effects of various spraying conditions including standoff distance, torch power, number of torch passes, types of solvent and plasma velocity were investigated. The as-sprayed coating demonstrated a hierarchically structured surface topography, which closely resembles superhydrophobic surfaces found in nature. The water contact angle on the SPPS superhydrophobic coating was up to 65% higher than on smooth REO surfaces. PMID:27091306

  10. An Indian Ocean precursor for Indian summer monsoon rainfall variability

    NASA Astrophysics Data System (ADS)

    Sreejith, O. P.; Panickal, S.; Pai, S.; Rajeevan, M.

    2015-11-01

    The Indian summer monsoon rainfall (ISMR) depicts large interannual variability strongly linked with El Niño-Southern Oscillation (ENSO). However, many of the El Niño years were not accompanied by deficient ISMR. The results from the study reveal the significant role of coupled air-sea interaction over the tropical Indian Ocean (IO) in modifying the ENSO-ISMR association. The IO warm water volume (WWV), a measure of heat content variations in the equatorial IO has strong influence on ISMR. A deepening (shoaling) of thermocline in the eastern equatorial IO (EEIO) during late boreal spring (April-May) accompanied by increase (decrease) in WWV anomalies weaken (enhance) the ISMR by enhancing (suppressing) the convection over EEIO resulting in the below (above) normal ISMR. Thus, the changes in the WWV anomalies in the EEIO along with ENSO conditions during boreal spring can be considered as a precursor for the performance of subsequent ISMR.

  11. Malignant Glomus Tumor Arising in a Long Standing Precursor Lesion.

    PubMed

    Damavandy, Ali Alexander; Anatelli, Florencia; Skelsey, Maral Kibarian

    2016-05-01

    Malignant glomus tumor is an exceedingly rare vascular malignancy of unclear etiology, which is believed to arise de novo or from malignant transformation of a benign glomus tumor. The authors present a case of an elderly woman evaluated for a painful 2.5-cm purple-brown tumor on the right forearm that grew rapidly within a long-standing, seemingly benign lesion. An excisional biopsy revealed a multilobular dermal tumor composed of areas of benign-appearing glomus tumor cells interspersed with areas of dense, pleomorphic cells arranged in sheets and fascicles with an elevated mitotic rate. The diagnosis of malignant glomus tumor was made on the basis of the lesion's nuclear atypia and elevated mitotic rate. This case demonstrates malignant transformation of a presumably benign glomus tumor precursor lesion highlighting this rarely reported phenomenon. The authors present this case to raise awareness of this vascular malignancy that carries a significant risk of metastasis. PMID:26760685

  12. Bioexcimers as Precursors of Charge Transfer and Reactivity in Photobiology

    SciTech Connect

    Serrano-Andres, Luis; Merchan, Manuela; Roca-Sanjuan, Daniel; Olaso-Gonzalez, Gloria; Rubio, Mercedes

    2007-11-29

    Accurate CASPT2//CASSCF calculations show that {pi}-stacked interactions in different biochromophores such as DNA nucleobases or porphyrin-quinone pairs yield excimer-like situations which behave as precursors of processes like charge transfer or photoreactivity. Examples are the transfer of charge between a reduced pheophytin and an accepting quinone molecule, process that trigger the sequence of electron transfer phenomena in photosynthetic photosystem II, the electron transfer between adjacent DNA nucleobases in a strand of oligonucleotides, and the photodimerization taking place in cytosine pairs leading to cyclobutanecytosine mutants. These processes take place through nonadiabatic photochemical mechanisms whose evolution is determined by the presence and accessibility of conical intersections and other surface crossings between different electronic states.

  13. Glutathione peroxidase 4 prevents necroptosis in mouse erythroid precursors

    PubMed Central

    Canli, Özge; Alankuş, Yasemin B.; Grootjans, Sasker; Vegi, Naidu; Hültner, Lothar; Hoppe, Philipp S.; Schroeder, Timm; Vandenabeele, Peter; Bornkamm, Georg W.

    2016-01-01

    Maintaining cellular redox balance is vital for cell survival and tissue homoeostasis because imbalanced production of reactive oxygen species (ROS) may lead to oxidative stress and cell death. The antioxidant enzyme glutathione peroxidase 4 (Gpx4) is a key regulator of oxidative stress–induced cell death. We show that mice with deletion of Gpx4 in hematopoietic cells develop anemia and that Gpx4 is essential for preventing receptor-interacting protein 3 (RIP3)-dependent necroptosis in erythroid precursor cells. Absence of Gpx4 leads to functional inactivation of caspase 8 by glutathionylation, resulting in necroptosis, which occurs independently of tumor necrosis factor α activation. Although genetic ablation of Rip3 normalizes reticulocyte maturation and prevents anemia, ROS accumulation and lipid peroxidation in Gpx4-deficient cells remain high. Our results demonstrate that ROS and lipid hydroperoxides function as not-yet-recognized unconventional upstream signaling activators of RIP3-dependent necroptosis. PMID:26463424

  14. Immunophenotype of mouse cerebral hemispheres-derived neural precursor cells.

    PubMed

    Poulatsidou, Kyriaki-Nefeli; Lagoudaki, Roza; Touloumi, Olga; Kesidou, Evangelia; Boziki, Marina; Ravanidis, Stylianos; Chlichlia, Katerina; Grigoriou, Maria; Grigoriadis, Nikolaos

    2016-01-12

    Postnatally isolated neural precursor cells (piNPCs) from mouse cerebral tissue have been studied in cell-based therapeutic approaches for Experimental Autoimmune Encephalomyelitis (EAE). Transplantation experiments in EAE rodents revealed that piNPCs manage to integrate into the host tissue and ameliorate clinical symptoms. When cultured in vitro, mouse cerebral piNPCs form neurospheres consisting of immature cells positive for polysialylated neural adhesion molecule (PSA-NCAM) that differentiate mainly towards glial cells, but also neurons. Herein, we have characterized piNPCs immunophenotype, with flow cytometry. NPCs were positive for CD24, CD44, and CD133 though negative for CD15, CD184 and CD49d. This immunophenotype, determined for the first time, among cells isolated from neonates might be useful for the identification of NPC population aiming at the development of transplantation protocols. PMID:26590329

  15. Illegal or legitimate use? Precursor compounds to amphetamine and methamphetamine.

    PubMed

    Musshoff, F

    2000-02-01

    The interpretation of methamphetamine and amphetamine positive test results in biological samples is a challenge to clinical and forensic toxicology for several reasons. The effects of pH and dilution of urine samples and the knowledge about legitimate and illicit sources have to be taken into account. Besides a potentially legal prescription of amphetamines, many substances metabolize to methamphetamine or amphetamine in the body: amphetaminil, benzphetamine, clobenzorex, deprenyl, dimethylamphetamine, ethylamphetamine, famprofazone, fencamine, fenethylline, fenproporex, furfenorex, mefenorex, mesocarb, and prenylamine. Especially the knowledge of potential origins of methamphetamine and amphetamine turns out to be very important to prevent a misinterpretation of the surrounding circumstances and to prove illegal drug abuse. In this review, potential precursor compounds are described, including their medical use and major clinical effects and their metabolic profiles, as well as some clues which help to identify the sources. PMID:10711406

  16. Damage precursor measurements on UV-optical coatings

    SciTech Connect

    Ettrich, K.; Blaschke, H.; Welsch, E.

    1995-12-31

    For application in UV thin film optics the thermal contribution to the laser-induced optical breakdown was investigated utilizing time-resolved photothermal probe beam deflection (MIRAGE) technique. The potentiality of this method for the determination of both the subdamage range and the onset of single-shot-damage of Al{sub 2}O{sub 3}/SiO{sub 2} and LaF{sub 3}/MgF{sub 2} high-reflective coatings by using the thermal branch of the MIRAGE technique could be demonstrated. Examining the dielectric mirrors by 248 nm KrF laser irradiation, distinct damage precursor features were found. Thus, the physical origin of the UV pulsed radiation breakdown in HR coatings can be elucidated.

  17. Clinical and biological significance of precursor lesions of intrahepatic cholangiocarcinoma.

    PubMed

    Ettel, Mark; Eze, Ogechukwu; Xu, Ruliang

    2015-11-01

    Cholangiocarcinoma (CC) is primarily a malignant tumor of older adults most prevalent in Southeast Asia, where liver fluke infestation is high. However the etiology in western countries is unknown. Although the incidence of extrahepatic cholangiocarcinoma has remained constant, incidence of intrahepatic CC (ICC) which differs in morphology, pathogenesis, risk factors, treatment and prognosis is increasing. While this increase is associated with hepatitis C virus infection, chronic nonalcoholic liver disease, obesity, and smoking, the pathogenesis of ICC and molecular alterations underlying the carcinogenesis are not completely elucidated. Benign biliary lesions such as biliary intraepithelial neoplasia, intraductal papillary neoplasm of the bile duct, von Meyenburg complex or bile duct hamartoma, and bile duct adenoma have been associated with ICC. For each of these entities, evidence suggests or supports a role as premalignant lesions. This article summarized the important biological significance of the precursor lesions of ICC and the molecular mechanisms that may be involved in intrahepatic cholangiocarcinogenesis. PMID:26557948

  18. Clinical and biological significance of precursor lesions of intrahepatic cholangiocarcinoma

    PubMed Central

    Ettel, Mark; Eze, Ogechukwu; Xu, Ruliang

    2015-01-01

    Cholangiocarcinoma (CC) is primarily a malignant tumor of older adults most prevalent in Southeast Asia, where liver fluke infestation is high. However the etiology in western countries is unknown. Although the incidence of extrahepatic cholangiocarcinoma has remained constant, incidence of intrahepatic CC (ICC) which differs in morphology, pathogenesis, risk factors, treatment and prognosis is increasing. While this increase is associated with hepatitis C virus infection, chronic nonalcoholic liver disease, obesity, and smoking, the pathogenesis of ICC and molecular alterations underlying the carcinogenesis are not completely elucidated. Benign biliary lesions such as biliary intraepithelial neoplasia, intraductal papillary neoplasm of the bile duct, von Meyenburg complex or bile duct hamartoma, and bile duct adenoma have been associated with ICC. For each of these entities, evidence suggests or supports a role as premalignant lesions. This article summarized the important biological significance of the precursor lesions of ICC and the molecular mechanisms that may be involved in intrahepatic cholangiocarcinogenesis. PMID:26557948

  19. Migration and differentiation of transplanted human neural precursor cells.

    PubMed

    Jain, Meena; Armstrong, Richard J E; Elneil, Suzie; Rosser, Anne E; Barker, Roger A

    2003-07-01

    In this study we have examined the migration and phenotypic differentiation of human expanded neural precursors (hENPs) when transplanted into the intact adult rat brain. Primary human embryonic cortical cells and hENPs derived from the same source but expanded epigenetically in culture for two different time periods were transplanted into the rodent striatum and hippocampus. Histological analysis showed that overall the number of neurons decreased with time spent in culture prior to transplantation within the core of the graft regardless of site of implantation. Furthermore, transplanted cells migrated away from the graft to a similar extent irrespective of time in culture and site of implantation, although significantly more migrated cells were of a neuronal phenotype following transplantation into the hippocampus. PMID:12824771

  20. Single Source Precursors for Thin Film Solar Cells

    NASA Technical Reports Server (NTRS)

    Banger, Kulbinder K.; Hollingsworth, Jennifer A.; Harris, Jerry D.; Cowen, Jonathan; Buhro, William E.; Hepp, Aloysius F.

    2002-01-01

    The development of thin film solar cells on flexible, lightweight, space-qualified substrates provides an attractive cost solution to fabricating solar arrays with high specific power, (W/kg). The use of a polycrystalline chalcopyrite absorber layer for thin film solar cells is considered as the next generation photovoltaic devices. At NASA GRC we have focused on the development of new single source precursors (SSP) and their utility to deposit the chalcopyrite semi-conducting layer (CIS) onto flexible substrates for solar cell fabrication. The syntheses and thermal modulation of SSPs via molecular engineering is described. Thin-film fabrication studies demonstrate the SSPs can be used in a spray CVD (chemical vapor deposition) process, for depositing CIS at reduced temperatures, which display good electrical properties, suitable for PV (photovoltaic) devices.

  1. Molecular and polymeric ceramic precursors. Research progress report

    SciTech Connect

    Sneddon, L.G.

    1992-06-01

    The development of new methods for the production of complex materials is one of the most important problems in modern solid state chemistry and materials science. This project is attempting to apply the synthetic principles which have evolved in inorganic and organometallic chemistry to the production of technologically important non-oxide ceramics, such as boron nitride, boron carbide and metal borides. Recent work has now resulted in the production of new polymer systems, including poly(B-vinylborazine), polyvinylpentaborane and polyborazylene, that have proven to be high yield precursors to boron-based ceramic materials. Current work is now directed toward the synthesis of new types of molecular and polymeric boron-containing species and an exploration of the solid state properties of the ceramics that have been produced in these studies.

  2. B-cell precursors in early chicken embryos.

    PubMed Central

    Lebacq, A M; Ritter, M A

    1979-01-01

    The ontogeny of B-cell precursors in chicken embryos from day 3 of incubation onwards has been studied. Purified antibodies to chicken Ig L, gamma, mu, alpha chains were used in a sensitive indirect immunofluorescence assayed on fixed cell smears and wax-embedded tissue sections; the location and morphology of immunoglobulin positive (Ig+) cells were determined either in phase contrast or after histological staining. Lymphoid cells containing small amounts of cytoplasmic immunoglobulin were found in 3 day and older embryonic yolk sac, 11 and 12 day blood, 11, 12 and 13 day bursal mesenchyme. cIg+ large basophilic cells were first seen in 14 day bursal follicles. It is concluded that cells enter the embryonic bursa at different developmental stages: some appear to be uncommitted stem cells, whilst others have already commenced B-cell maturation in an extra-bursal site. Images Figure 1 Figure 2 PMID:381171

  3. Superhydrophobic Ceramic Coatings by Solution Precursor Plasma Spray

    PubMed Central

    Cai, Yuxuan; Coyle, Thomas W.; Azimi, Gisele; Mostaghimi, Javad

    2016-01-01

    This work presents a novel coating technique to manufacture ceramic superhydrophobic coatings rapidly and economically. A rare earth oxide (REO) was selected as the coating material due to its hydrophobic nature, chemical inertness, high temperature stability, and good mechanical properties, and deposited on stainless steel substrates by solution precursor plasma spray (SPPS). The effects of various spraying conditions including standoff distance, torch power, number of torch passes, types of solvent and plasma velocity were investigated. The as-sprayed coating demonstrated a hierarchically structured surface topography, which closely resembles superhydrophobic surfaces found in nature. The water contact angle on the SPPS superhydrophobic coating was up to 65% higher than on smooth REO surfaces. PMID:27091306

  4. Observation of a medium-term earthquake precursor in Irkutsk

    NASA Astrophysics Data System (ADS)

    Basov, A. D.; Chernykh, E. N.

    2010-01-01

    Complex geophysical investigations of the earth dam of the Irkutsk hydroelectric power plant (HEP) revealed strong negative anomalies of the natural electric field (NEF). These anomalies are associated with focal mechanisms of earthquakes, in which subhorizontal compressive stresses prevail. The sources of such earthquakes are located in the south of the Baikal rift zone. Their epicentral distances are comparable with the range of the action of precursors of earthquakes with M > 5. NEF anomalies correlate with an increase in the filtration at the earth’s dam base in the Angara fault zone along the Angara River bed. In the shape of their plots, manifestations of these NEF anomalies are similar to variations in the ratios of velocities of longitudinal and transverse waves before earthquakes in the Garm region.

  5. Oligodendrocyte precursors migrate along vasculature in the developing nervous system.

    PubMed

    Tsai, Hui-Hsin; Niu, Jianqin; Munji, Roeben; Davalos, Dimitrios; Chang, Junlei; Zhang, Haijing; Tien, An-Chi; Kuo, Calvin J; Chan, Jonah R; Daneman, Richard; Fancy, Stephen P J

    2016-01-22

    Oligodendrocytes myelinate axons in the central nervous system and develop from oligodendrocyte precursor cells (OPCs) that must first migrate extensively during brain and spinal cord development. We show that OPCs require the vasculature as a physical substrate for migration. We observed that OPCs of the embryonic mouse brain and spinal cord, as well as the human cortex, emerge from progenitor domains and associate with the abluminal endothelial surface of nearby blood vessels. Migrating OPCs crawl along and jump between vessels. OPC migration in vivo was disrupted in mice with defective vascular architecture but was normal in mice lacking pericytes. Thus, physical interactions with the vascular endothelium are required for OPC migration. We identify Wnt-Cxcr4 (chemokine receptor 4) signaling in regulation of OPC-endothelial interactions and propose that this signaling coordinates OPC migration with differentiation. PMID:26798014

  6. Superhydrophobic Ceramic Coatings by Solution Precursor Plasma Spray

    NASA Astrophysics Data System (ADS)

    Cai, Yuxuan

    Superhydrophobic surfaces exhibit superior water repellent properties, and they have remarkable potential to improve current energy infrastructure. Substantial research has been performed on the production of superhydrophobic coatings. However, superhydrophobic coatings have not yet been adopted in many industries where potential applications exist due to the limited durability of the coating materials and the complex and costly fabrication processes. Here presented a novel coating technique to manufacture ceramic superhydrophobic coatings rapidly and economically. A rare earth oxide (REO) was selected as the coating material due to its hydrophobic nature and strong mechanical properties, and deposited on stainless steel substrates by solution precursor plasma spray (SPPS). The as-sprayed coating demonstrated a hierarchically structured coating topography, which closely resembles superhydrophobic surfaces in nature. Compared to smooth REO surfaces, the SPPS superhydrophobic coating improved the water contact angle by as much as 65° after vacuum treatment at 1 Pa for 48 hours.

  7. Phosphatidylglyceroylalkylamine, a novel phosphoglycolipid precursor in Deinococcus radiodurans

    SciTech Connect

    Huang, Y.; Anderson, R. )

    1991-01-01

    We report here the structure of a previously uncharacterized phospholipid in the radiation-resistant bacterium Deinococcus radiodurans. This phospholipid, designated lipid 4, was shown by chemical analysis, HF hydrolysis, and nuclear magnetic resonance spectroscopy to be phosphatidylglyceroylalkylamine. Lipid 4 thus contains the unusual lipid constituents glyceric acid and alkylamines, which have previously been identified in two complex phosphoglycolipids from this organism. By ({sup 32}P)phosphate pulse-chase labeling techniques, lipid 4 was shown to be the precursor of the complex phosphoglycolipids alpha-galactosyl- and alpha-N-acetylglucosaminylphosphatidylglyceroylalkylamine. While phosphatidylglyceroylalkylamine is rapidly biosynthesized from Pi, its subsequent glycosylation occurs much more slowly. Therefore, we conclude that the final glycosylation step is the rate-limiting event in the biosynthesis of the complex phosphoglycolipids alpha-galactosyl- and alpha-N-acetylglucosaminyl-phosphatidylglyceroylalkylamine.

  8. CXCR7 Is Involved in Human Oligodendroglial Precursor Cell Maturation

    PubMed Central

    Göttle, Peter; Kuhlmann, Tanja; Hartung, Hans-Peter; Antel, Jack; Küry, Patrick

    2016-01-01

    Differentiation of oligodendroglial precursor cells (OPCs), a crucial prerequisite for central nervous system (CNS) remyelination in diseases such as Multiple Sclerosis (MS), is modulated by a multitude of extrinsic and intrinsic factors. In a previous study we revealed that the chemokine CXCL12 stimulates rodent OPC differentiation via activation of its receptor CXCR7. We could now demonstrate that CXCR7 is also expressed on NogoA- and Nkx2.2-positive oligodendroglial cells in human MS brains and that stimulation of cultured primary fetal human OPCs with CXCL12 promotes their differentiation as measured by surface marker expression and morphologic complexity. Pharmacological inhibition of CXCR7 effectively blocks these CXCL12-dependent effects. Our findings therefore suggest that a specific activation of CXCR7 could provide a means to promote oligodendroglial differentiation facilitating endogenous remyelination activities. PMID:26741980

  9. Aluminum borate nanowires from the pyrolysis of polyaminoborane precursors.

    PubMed

    Du, Van An; Jurca, Titel; Whittell, George R; Manners, Ian

    2016-01-21

    Polyaminoboranes [N(R)H-BH2]n (1: R = H, 2: R = Me) were pyrolyzed on a range of substrates: silicon, metal foils (stainless steel, nickel, and rhodium), and sapphire wafers, as well as on Al2O3 and AlN powders. The pyrolysis of 2 on a Si-wafer resulted in porous nanostructures containing hexagonal-boron nitride (h-BN). In the case of 1 or H3N·BH3 as precursor, using rhodium foil as substrate afforded amorphous B and N-containing nanostructures, and polydisperse spherical nanoparticles, respectively. Switching the substrate to sapphire wafers, as well as to Al2O3 or AlN powders, resulted in formation of crystalline Al5BO9 nanostructures (nanowires, nanotubes, and nanoribbons). For sapphire wafers, the size of the resulting nanowires was influenced by modifying the surface defect density. PMID:26649782

  10. Ceria Nanotube Formed by Sacrificed Precursors Template through Oswald Ripening

    PubMed Central

    Pang, Laixue; Wang, Xiaoying; Tang, Xinde

    2015-01-01

    Controllable preparation of ceria nanotube was realized by hydrothermal treatment of Ce(OH)CO3 precursors. The gradually changing morphologies and microstructures of cerium oxide were characterized by X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. A top-down path is illuminated to have an insight to the morphological transformation from nanorod to nanotube by adjusting the reaction time. The growth process is investigated by preparing a series of intermediate morphologies during the shape evolution of CeO2nanostructure based on the scanning electron microscopy image observation. On the basis of the time-dependent experimental observation, the possible formation mechanism related to oriented attachment and Oswald ripening was proposed, which might afford some guidance for the synthesis of other inorganic nanotubes. PMID:26151866

  11. NASAs Evolvable Mars Campaign: Mars Moons Robotic Precursor

    NASA Technical Reports Server (NTRS)

    Gernhardt, Michael L.; Abercromby, Andrew F. J.; Abell, Paul A.; Love, Stanley G.; Lee, David E.; Chappell, Steven P.; Howe, A. Scott; Friedensen, Victoria

    2015-01-01

    Human exploration missions to the moons of Mars are being considered within NASA's Evolvable Mars Campaign (EMC) as an intermediate step for eventual human exploration and pioneering of the surface of Mars. A range of mission architectures is being evaluated in which human crews would explore one or both moons for as little as 14 days or for as long as 500 days with a variety of orbital and surface habitation and mobility options being considered. Relatively little is known about the orbital, surface, or subsurface characteristics of either moon. This makes them interesting but challenging destinations for human exploration missions during which crewmembers must be able to effectively conduct scientific exploration without being exposed to undue risks due to radiation, dust, micrometeoroids, or other hazards. A robotic precursor mission to one or both moons will be required to provide data necessary for the design and operation of subsequent human systems and for the identification and prioritization of scientific exploration objectives. This paper identifies and discusses considerations for the design of such a precursor mission based on current human mission architectures. Objectives of a Mars' moon precursor in support of human missions are expected to include: 1) identifying hazards on the surface and the orbital environment at up to 50-km distant retrograde orbits; 2) collecting data on physical characteristics for planning of detailed human proximity and surface operations; 3) performing remote sensing and in situ science investigations to refine and focus future human scientific activities; and 4) prospecting for in situ resource utilization. These precursor objectives can be met through a combination or remote sensing (orbital) and in-situ (surface) measurements. Analysis of spacecraft downlink signals using radio science techniques would measure the moon's mass, mass distribution, and gravity field, which will be necessary to enable trajectory planning. Laser altimetry would precisely measure the moon's shape and improve the accuracy of radio science measurements. A telescopic imaging camera would map the moon at submeter resolution and photograph selected areas of interest at subcentimeter resolution and a visible and near-infrared (0.4-3.0 mm) imaging spectrograph would produce a global map of mineral composition variations at a resolution of tens of meters and maps of selected areas of interest at meter resolution. Additional remote sensing capabilities could include a thermal infrared imager (heat flow, thermal inertia, and grain size distributions), a gamma-ray and neutron detector (atomic composition), a ground-penetrating radar (internal structure), and a magnetometer and Langmuir probe (magnetic properties and plasma field). Once on the surface of Phobos or Deimos, necessary instrumentation would include a penetrometer (regolith compressive strength), a motion-imagery camera (to observe the penetrometer tests before, during, and after contact), a dust-adhesion witness plate and camera (dust levitation), a microimager (dust particle sizes and shapes), and an alpha-proton-X-ray, X-ray fluorescence, Mossbauer, or Raman spectrometer (atomic and mineral composition of surface materials) and an optional temperature probe (regolith thermal properties). A variety of robotic mission design options to enable both orbital and surface measurements are being considered that include fully integrated and modular approaches. In-situ measurements from at least one surface location would be required, with additional measurement locations possible through use of multiple landers, through propulsive relocation of a single lander, or through electromechanical surface translation by a walking or hopping lander vehicle, which could also serve to evaluate such mobility capabilities for subsequent human missions. Preliminary orbital analysis suggests that remote sensing would likely be performed while in a distant retrograde orbit around the target moon. Mission design options to enable characterization of both Mars’ moons in a single mission are also being studied.

  12. Precursors to numeracy in kindergartners with specific language impairment.

    PubMed

    Kleemans, Tijs; Segers, Eliane; Verhoeven, Ludo

    2011-01-01

    The present study investigated to what extent children with specific language impairment (SLI) differ in their early numeracy skills, when compared to normal language achieving (NLA) children. It was also explored which precursors were related to the early numeracy skills in both groups. Sixty-one children with SLI (6; 1 years) and 111 NLA children (6; 2 years) were assessed on general intelligence, working memory, naming speed, linguistic ability and early numeracy skills. The results showed lower scores for the children with SLI on logical operations and numeral representations but not on numeral estimations. The variance in numeral estimations was explained by children's intelligence and visual spatial memory. Phonological awareness and grammatical ability explained the variance in logical operations and numeral representations whereas naming speed turned out to be an additional factor in predicting these early numeracy skills of children with SLI. PMID:21640551

  13. Structural precursor to freezing: An integral equation study

    NASA Astrophysics Data System (ADS)

    Brader, Joseph M.

    2008-03-01

    Recent simulation studies have drawn attention to the shoulder which forms in the second peak of the radial distribution function of hard spheres at densities close to freezing and which is associated with local crystalline ordering in the dense fluid. We address this structural precursor to freezing using an inhomogeneous integral equation theory capable of describing local packing constraints to a high level of accuracy. The addition of a short-range attractive interaction leads to a well known broadening of the fluid-solid coexistence region as a function of attraction strength. The appearance of a shoulder in our calculated radial distribution functions is found to be consistent with the broadened coexistence region for a simple model potential, thus demonstrating that the shoulder is not exclusively a high density packing effect.

  14. Is there a field-theoretic explanation for precursor biopolymers?

    PubMed

    Rosen, Gerald

    2002-08-01

    A Hu-Barkana-Gruzinov cold dark matter scalar field phi may enter a weak isospin invariant derivative interaction that causes the flow of right-handed electrons to align parallel to (inverted delta phi). Hence, in the outer regions of galaxies where (inverted delta phi) is large, as in galactic halos, the derivative interaction may induce a chirality-imbued quantum chemistry. Such a chirality-imbued chemistry would in turn be conducive to the formation of abundant precursor biopolymers on interstellar dust grains, comets and meteors in galactic halo regions, with subsequent delivery to planets in the inner galactic regions where phi and (inverted delta phi) are concomitantly near zero and left-right symmetric terrestrial quantum chemistry prevails. PMID:12458734

  15. Precursors to schizophrenia: do biological markers have specificity?

    PubMed

    Tarrant, C J; Jones, P B

    1999-05-01

    This review addresses childhood antecedents and biological markers of schizophrenia within a neurodevelopmental framework. General-population birth-cohort studies illustrate delays in developmental milestones, abnormalities in social functioning, and cognitive deficits throughout childhood, adolescence, and early adulthood. Abnormal neurology and motor dysfunction have been measured in children prior to the onset of schizophrenia, at first onset of disease, and in those with chronic schizophrenia. Minor physical anomalies, a static marker of developmental disturbance, are also increased in schizophrenia. None of these factors has high specificity for this disorder. This review examines the associations between these precursors and some etiological factors for schizophrenia, comments on their lack of complete specificity to this psychotic syndrome, and considers their usefulness as predictors of risk. PMID:10332574

  16. Oxidation and formation of deposit precursors in hydrocarbon fuels

    NASA Technical Reports Server (NTRS)

    Buttrill, S. E., Jr.; Mayo, F. R.; Lan, B.; St.john, G. A.; Dulin, D.

    1982-01-01

    A practical fuel, home heating oil no. 2 (Fuel C), and the pure hydrocarbon, n-dodecane, were subjected to mild oxidation at 130 C and the resulting oxygenated reaction products, deposit precursors, were analyzed using field ionization mass spectrometry. Results for fuel C indicated that, as oxidation was initially extended, certain oxygenated reaction products of increasing molecular weights in the form of monomers, dimers and some trimers were produced. Further oxidation time increase resulted in further increase in monomers but a marked decrease in dimers and trimers. This suggests that these larger molecular weight products have proceeded to form deposit and separated from the fuel mixture. Results for a dodecane indicated that yields for dimers and trimers were very low. Dimers were produced as a result of interaction between oxygenated products with each other rather than with another fuel molecule. This occurred even though fuel molecule concentration was 50 times, or more greater than that for these oxygenated reaction products.

  17. Electrochemical behavior of carbon aerogels derived from different precursors

    SciTech Connect

    Pekala, R.W.; Alviso, C.T.; Nielson, J.K.; Tran, T.D.; Reynolds, G.M.; Dresshaus, M.S.

    1995-04-01

    The ability to tailor the structure and properties of porous carbons has led to their increased use as electrodes in energy storage devices. Our research focuses on the synthesis and characterization of carbon aerogels for use in electrochemical double layer capacitors. Carbon aerogels are formed from the sol-gel polymerization of (1) resorcinol-formaldehyde or (2) phenolic-furfural, followed by supercritical drying from carbon dioxide, and subsequent pyrolysis in an inert atmosphere. These materials can be produced as monoliths, composites, thin films, powders, or microspheres. In all cases, the areogels have an open-cell structure with an ultrafine pore size (<100 nm), high surface area (400-1 100 m{sup 2}/g), and a solid matrix composed of interconnected particles, fibers, or platelets with characteristic dimensions of 10 nm. This paper examines the effects of the carbon precursor and processing conditions on electrochemical performance in aqueous and organic electrolytes.

  18. Long-period geomagnetic pulsations as solar flare precursors

    NASA Astrophysics Data System (ADS)

    Barkhatov, N. A.; Obridko, V. N.; Revunov, S. E.; Snegirev, S. D.; Shadrukov, D. V.; Sheiner, O. A.

    2016-03-01

    We compare long-period pulsations of the horizontal component of the geomagnetic field at intervals that precede extreme solar flares. To this end, we use the wavelet-skeleton technique to process the geomagnetic field disturbances recorded at magnetic stations over a wide geographical range. The synchronization times of wavelet-skeleton spectral distributions of long-period pulsations of geomagnetic oscillations over all magnetic stations are shown as normalized histograms. A few days before an intense solar flare, the histograms show extremes. This means that these extremes can be regarded as flare precursors. The same technique is used to analyze the parameters of near-Earth space. The histograms obtained in this case are free of the aforementioned extrema and, therefore, cannot point to an upcoming flare. The goal of this study is to construct a correlation-spectral method for the short-term prediction of solar flare activity.

  19. Natural Modulators of Amyloid-Beta Precursor Protein Processing

    PubMed Central

    Zhang, Can; Tanzi, Rudolph E.

    2013-01-01

    Alzheimers disease (AD) is a devastating neurodegenerative disease and the primary cause of dementia, with no cure currently available. The pathogenesis of AD is believed to be primarily driven by A?, the principal component of senile plaques. A? is an ~4 kDa peptide generated from the amyloid-? precursor protein (APP) through proteolytic secretases. Natural products, particularly those utilized in traditional Chinese medicine (TCM), have a long history alleviating common clinical disorders, including dementia. However, the cell/molecular pathways mediated by these natural products are largely unknown until recently when the underlying molecular mechanisms of the disorders begin to be elucidated. Here, the mechanisms with which natural products modulate the pathogenesis of AD are discussed, in particular, by focusing on their roles in the processing of APP. PMID:22998566

  20. Single-source precursors for ternary chalcopyrite materials, and methods of making and using the same

    NASA Technical Reports Server (NTRS)

    Banger, Kulbinder K. (Inventor); Hepp, Aloysius F. (Inventor); Harris, Jerry D. (Inventor); Jin, Michael Hyun-Chul (Inventor); Castro, Stephanie L. (Inventor)

    2006-01-01

    A single source precursor for depositing ternary I-III-VI.sub.2 chalcopyrite materials useful as semiconductors. The single source precursor has the I-III-VI.sub.2 stoichiometry built into a single precursor molecular structure which degrades on heating or pyrolysis to yield the desired I-III-VI.sub.2 ternary chalcopyrite. The single source precursors effectively degrade to yield the ternary chalcopyrite at low temperature, e.g. below 500.degree. C., and are useful to deposit thin film ternary chalcopyrite layers via a spray CVD technique. The ternary single source precursors according to the invention can be used to provide nanocrystallite structures useful as quantum dots. A method of making the ternary single source precursors is also provided.

  1. Comparative examination of titania nanocrystals synthesized by peroxo titanic acid approach from different precursors.

    PubMed

    Liu, Yong-Jun; Aizawa, Mami; Wang, Zheng-Ming; Hatori, Hiroaki; Uekawa, Naofumi; Kanoh, Hirofumi

    2008-06-15

    Titanium dioxide nanocrystalline particles were synthesized by peroxo titanium acid (PTA) approach from titanium alkoxide and inorganic salt precursors, and their structural and surface properties, porosities, and photocatalytic activities were comparatively examined by XRD, TG/DTA, DRIFT, UV-vis, low temperature N(2) adsorption, and methyl orange (MO) degradation. It was found that nanoparticles with single anatase phase can be obtained from alkoxide precursor even near room temperature if synthesis conditions are appropriately controlled. PTA-derived anatase nanoparticles from titanium alkoxide precursor have smaller crystalline sizes and better porosities, and contain less amount of peroxo group and no organic impurities as compared to those from TiCl(4) precursor. The advantages in structural property, porosity, and surface properties (few deficiencies) lead to a much better photocatalytic activity for TiO(2) nanoparticles from titanium alkoxide precursor in comparison with those from TiCl(4) precursor. PMID:18406418

  2. Multiple precursors of secondary mineralogical assemblages in CM chondrites

    NASA Astrophysics Data System (ADS)

    Pignatelli, Isabella; Marrocchi, Yves; Vacher, Lionel. G.; Delon, RéMi; Gounelle, Matthieu

    2016-03-01

    We report a petrographic and mineralogical survey of tochilinite/cronstedtite intergrowths (TCIs) in Paris, a new CM chondrite considered to be the least altered CM identified to date. Our results indicate that type-I TCIs consist of compact tochilinite/cronstedtite rims surrounding Fe-Ni metal beads, thus confirming kamacite as the precursor of type-I TCIs. In contrast, type-II TCIs are characterized by complex compositional zoning composed of three different Fe-bearing secondary minerals: from the outside inwards, tochilinite, cronstedtite, and amakinite. Type-II TCIs present well-developed faces that allow a detailed morphological analysis to be performed in order to identify the precursors. The results demonstrate that type-II TCIs formed by pseudomorphism of the anhydrous silicates, olivine, and pyroxene. Hence, there is no apparent genetic relationship between type-I and type-II TCIs. In addition, the complex chemical zoning observed within type-II TCIs suggests that the alteration conditions evolved dramatically over time. At least three stages of alteration can be proposed, characterized by alteration fluids with varying compositions (1) Fe- and S-rich fluids; (2) S-poor and Fe- and Si-rich fluids; and (3) S- and Si-poor, Fe-rich fluids. The presence of unaltered silicates in close association with euhedral type-II TCIs suggests the existence of microenvironments during the first alteration stages of CM chondrites. In addition, the absence of Mg-bearing secondary minerals in Paris TCIs suggests that the Mg content increases during the course of alteration.

  3. First results on GlioLab/GlioSat Precursors Missions

    NASA Astrophysics Data System (ADS)

    Cappelletti, Chantal; Notarangelo, Angelo; Demoss, Darrin; Carella, Massimo

    2012-07-01

    Since 2009 GAUSS group is involved in a joint collaboration with Morehead State University (MSU) Space Science Center and IRCCS Casa Sollievo della Sofferenza (CSS) research labs with the aim to design a biomedical project in order to investigate if the combined effects of microgravity conditions and ionizing radiation increase or decrease the survival rate of cancer cells. The biological sample consists of Glioblastoma cancer cell line ANGM-CSS. Glioblastoma is a kind of cancer that can be treated after surgery only by radiotherapy using ionizing radiation. This treatment, anyway, results in a very low survival rate. This project uses different university space platforms: a CubeLab, named GlioLab, on board the International Space Station and the university microsatellite UniSat-5 designed by GAUSS. In addition a GlioLab/GlioSat precursor experiment has already flown two times with the Space Shuttle during the missions STS-134 and STS-135. The phase 0 or the precursor of GlioLab uses a COTS system, named Liquid Mixing Apparatus (LMA), to board the biological samples inside the Space Shuttle for thirty day . The LMA allows to board liquids inside a vial but is not equipped with environment control system. After landing the samples were investigated by researchers at CSS in Italy and at MSU in Kentucky. This paper deals with the experimental set up and the results obtained during the STS-134 and STS-135 missions and with the new evidences on the behavior of this kind of cancer. In particular the results obtained on the DNA analysis give a confirmation of the original idea of GLioLab/Gliosat project justifying the development of the two systems.

  4. Regulation of oligodendrocyte precursor maintenance by chondroitin sulphate glycosaminoglycans.

    PubMed

    Karus, Michael; Ulc, Annika; Ehrlich, Marc; Czopka, Tim; Hennen, Eva; Fischer, Julia; Mizhorova, Marija; Qamar, Naila; Brüstle, Oliver; Faissner, Andreas

    2016-02-01

    Chondroitin sulfate proteoglycans (CSPGs) have been proven to inhibit morphological maturation of oligodendrocytes as well as their myelination capabilities. Yet, it remained unclear, whether CSPGs and/or their respective chondroitin sulfate glycosaminoglycan (CS-GAG) side chains also regulate the oligodendrocyte lineage progression. Here, we initially show that CS-GAGs detected by the monoclonal antibody 473HD are expressed by primary rat NG2-positive oligodendrocyte precursor cells (OPCs) and O4-positive immature oligodendrocytes. CS-GAGs become down-regulated with ongoing oligodendrocyte differentiation. Enzymatic removal of the CS-GAG chains by the bacterial enzyme Chondroitinase ABC (ChABC) promoted spontaneous differentiation of proliferating rat OPCs toward O4-positive immature oligodendrocytes. Upon forced differentiation, the enzymatic removal of the CS-GAGs accelerated oligodendrocyte differentiation toward both MBP-positive and membrane forming oligodendrocytes. These processes were attenuated on enriched CSPG fractions, mainly consisting of Phosphacan/RPTPβ/ζ and to less extent of Brevican and NG2. To qualify CS-GAGs as universal regulators of oligodendrocyte biology, we finally tested the effect of CS-GAG removal on OPCs from different sources such as mouse cortical oligospheres, mouse spinal cord neurospheres, and most importantly human-induced pluripotent stem cell-derived radial glia-like neural precursor cells. For all culture systems used, we observed a similar inhibitory effect of CS-GAGs on oligodendrocyte differentiation. In conclusion, this study clearly suggests an important fundamental principle for complex CS-GAGs to regulate the oligodendrocyte lineage progression. Moreover, the use of ChABC in order to promote oligodendrocyte differentiation toward myelin gene expressing cells might be an applicable therapeutic option to enhance white matter repair. GLIA 2016;64:270-286. PMID:26454153

  5. Structural comparison of nickel electrodes and precursor phases

    NASA Technical Reports Server (NTRS)

    Cornilsen, Bahne C.; Shan, Xiaoyin; Loyselle, Patricia

    1989-01-01

    A summary of previous Raman spectroscopic results and a discussion of important structural differences in the various phases of active mass and active mass precurors are presented. Raman spectra provide unique signatures for these phases, and allow one to distinguish each phase, even when the compound is amorphous to X-rays (i.e., does not scatter X-rays because of a lack of order and/or small particle size). The structural changes incurred during formation, charge and discharge, cobalt addition, and aging will be discussed and related to electrode properties. Important structural differences include NiO2 layer stacking, nonstoichiometry (especially cation-deficit nonstoichiometry), disorder, dopant content, and water content. The results indicate that optimal nickel active mass is non-close packed and nonstoichiometric. The formation process transforms precursor phases into this structure. Therefore, the precursor disorder, or lack thereof, influences this final active mass structure and the rate of formation. Aging processes induce structural change which is believed to be detrimental. The role of cobalt addition can be appreciated in terms of structures favored or stabilized by the dopant. In recent work, the in situ Raman technique to characterize the critical structural parameters was developed. An in situ method relates structure, electrochemistry, and preparation. In situ Raman spectra of cells during charge and discharge, either during cyclic voltammetry or under constant current conditions were collected. With the structure-preparation knowledge and the in situ Raman tool, it will be possible to define the structure-property-preparation relations in more detail. This instrumentation has application to a variety of electrode systems.

  6. The role of catalyst precursor anions in coal gasification

    SciTech Connect

    Abotsi, G.M.K.

    1992-08-28

    The aims of the proposed project are to enrich our understanding of the roles of various aqueous soluble catalyst precursor anions on the surface electrical properties of coal and to ascertain the influence of the surface charge on the adsorption, dispersion, and activities of calcium and potassium. These goals will be achieved by impregnating a North Dakota lignite (PSOC 1482) and its demineralized derivative with calcium or potassium catalyst precursors containing acetate (CH{sub 3}COO{sup {minus}}), chloride (Cl{sup {minus}}), nitrate (NO{sub 3}{sup {minus}}), sulfate (SO{sub 4}{sup 2{minus}}), and carbonate (CO{sub 3}{sup 2{minus}}) anions. Catalyst loading will be conducted under well-controlled conditions of solution pH and ionic strength. In the last quarter, the surface charge properties of the coal was determined as a function of acetate (CH{sub 3}COO{sup {minus}}), chloride (Cl{sup {minus}}), nitrate (NO{sup 3}{sup {minus}}), carbonate (CO{sub 3}{sup 2{minus}}) or sulfate (SO{sub 4}{sup 2{minus}})concentration using the respective potassium salts of these anions. In general, low anion concentrations (10{sup {minus}3} or 10{sup {minus}2} mol/L) had little effect on the zeta potentials of the coals. However, the surface charge densities of the coal become less negative at 10-1 mol/L of the nitrate, carbonate or sulfate anions. These trends suggest that the surface charge density of the coal is controlled by the adsorption of potassium ions (K{sup +}) onto the coal particles. The net negative charge on the coal panicles creates a repulsive force between the anions and the coal surface and prevents the anions from exerting any significant effect on the coal's electrokinetic properties.

  7. Human Myocardial Pericytes: Multipotent Mesodermal Precursors Exhibiting Cardiac Specificity

    PubMed Central

    Chen, William C.W.; Baily, James E.; Corselli, Mirko; Diaz, Mary; Sun, Bin; Xiang, Guosheng; Gray, Gillian A.; Huard, Johnny; Péault, Bruno

    2015-01-01

    Perivascular mesenchymal precursor cells (i.e. pericytes) reside in skeletal muscle where they contribute to myofiber regeneration; however, the existence of similar microvessel-associated regenerative precursor cells in cardiac muscle has not yet been documented. We tested whether microvascular pericytes within human myocardium exhibit phenotypes and multipotency similar to their anatomically and developmentally distinct counterparts. Fetal and adult human heart pericytes (hHPs) express canonical pericyte markers in situ, including CD146, NG2, PDGFRβ, PDGFRα, αSMA, and SM-MHC, but not CD117, CD133 and desmin, nor endothelial cell (EC) markers. hHPs were prospectively purified to homogeneity from ventricular myocardium by flow cytometry, based on a combination of positive- (CD146) and negative-selection (CD34, CD45, CD56, and CD117) cell lineage markers. Purified hHPs expanded in vitro were phenotypically similar to human skeletal muscle-derived pericytes (hSkMPs). hHPs express MSC markers in situ and exhibited osteo- chondro-, and adipogenic potentials but, importantly, no ability for skeletal myogenesis, diverging from pericytes of all other origins. hHPs supported network formation with/without ECs in Matrigel cultures; hHPs further stimulated angiogenic responses under hypoxia, markedly different from hSkMPs. The cardiomyogenic potential of hHPs was examined following 5-azacytidine treatment and neonatal cardiomyocyte co-culture in vitro, and intramyocardial transplantation in vivo. Results indicated cardiomyocytic differentiation in a small fraction of hHPs. In conclusion, human myocardial pericytes share certain phenotypic and developmental similarities with their skeletal muscle homologs, yet exhibit different antigenic, myogenic, and angiogenic properties. This is the first example of an anatomical restriction in the developmental potential of pericytes as native mesenchymal stem cells. PMID:25336400

  8. Human myocardial pericytes: multipotent mesodermal precursors exhibiting cardiac specificity.

    PubMed

    Chen, William C W; Baily, James E; Corselli, Mirko; Díaz, Mary E; Sun, Bin; Xiang, Guosheng; Gray, Gillian A; Huard, Johnny; Péault, Bruno

    2015-02-01

    Perivascular mesenchymal precursor cells (i.e., pericytes) reside in skeletal muscle where they contribute to myofiber regeneration; however, the existence of similar microvessel-associated regenerative precursor cells in cardiac muscle has not yet been documented. We tested whether microvascular pericytes within human myocardium exhibit phenotypes and multipotency similar to their anatomically and developmentally distinct counterparts. Fetal and adult human heart pericytes (hHPs) express canonical pericyte markers in situ, including CD146, NG2, platelet-derived growth factor receptor (PDGFR) β, PDGFRα, alpha-smooth muscle actin, and smooth muscle myosin heavy chain, but not CD117, CD133, and desmin, nor endothelial cell (EC) markers. hHPs were prospectively purified to homogeneity from ventricular myocardium by flow cytometry, based on a combination of positive- (CD146) and negative-selection (CD34, CD45, CD56, and CD117) cell lineage markers. Purified hHPs expanded in vitro were phenotypically similar to human skeletal muscle-derived pericytes (hSkMPs). hHPs express mesenchymal stem/stromal cell markers in situ and exhibited osteo-, chondro-, and adipogenic potentials but, importantly, no ability for skeletal myogenesis, diverging from pericytes of all other origins. hHPs supported network formation with/without ECs in Matrigel cultures; hHPs further stimulated angiogenic responses under hypoxia, markedly different from hSkMPs. The cardiomyogenic potential of hHPs was examined following 5-azacytidine treatment and neonatal cardiomyocyte coculture in vitro, and intramyocardial transplantation in vivo. Results indicated cardiomyocytic differentiation in a small fraction of hHPs. In conclusion, human myocardial pericytes share certain phenotypic and developmental similarities with their skeletal muscle homologs, yet exhibit different antigenic, myogenic, and angiogenic properties. This is the first example of an anatomical restriction in the developmental potential of pericytes as native mesenchymal stem cells. PMID:25336400

  9. Multiple precursors of secondary mineralogical assemblages in CM chondrites

    NASA Astrophysics Data System (ADS)

    Pignatelli, Isabella; Marrocchi, Yves; Vacher, Lionel. G.; Delon, RéMi; Gounelle, Matthieu

    2016-04-01

    We report a petrographic and mineralogical survey of tochilinite/cronstedtite intergrowths (TCIs) in Paris, a new CM chondrite considered to be the least altered CM identified to date. Our results indicate that type-I TCIs consist of compact tochilinite/cronstedtite rims surrounding Fe-Ni metal beads, thus confirming kamacite as the precursor of type-I TCIs. In contrast, type-II TCIs are characterized by complex compositional zoning composed of three different Fe-bearing secondary minerals: from the outside inwards, tochilinite, cronstedtite, and amakinite. Type-II TCIs present well-developed faces that allow a detailed morphological analysis to be performed in order to identify the precursors. The results demonstrate that type-II TCIs formed by pseudomorphism of the anhydrous silicates, olivine, and pyroxene. Hence, there is no apparent genetic relationship between type-I and type-II TCIs. In addition, the complex chemical zoning observed within type-II TCIs suggests that the alteration conditions evolved dramatically over time. At least three stages of alteration can be proposed, characterized by alteration fluids with varying compositions (1) Fe- and S-rich fluids; (2) S-poor and Fe- and Si-rich fluids; and (3) S- and Si-poor, Fe-rich fluids. The presence of unaltered silicates in close association with euhedral type-II TCIs suggests the existence of microenvironments during the first alteration stages of CM chondrites. In addition, the absence of Mg-bearing secondary minerals in Paris TCIs suggests that the Mg content increases during the course of alteration.

  10. The Fe/Mn constraint on precursors of basaltic achondrites

    NASA Technical Reports Server (NTRS)

    Delaney, Jeremy S.; Boesenberg, Joseph S.

    1993-01-01

    Most achondritic meteorites have Fe/Mn ratios that are lower than those of carbonaceous chondrites and of course are lower than the solar system abundance ratio of these elements. Models of the origin of achondritic assemblages must, therefore, account for these ratios. Fe/Mn ratios are suggested to be distinctive for samples from each achondrite parent body and for the Earth and Moon, but the correspondence between the Fe/Mn systematics of achondrites and chondritic precursors is unclear. Most models of achondrite genesis involve magmatic differentiation of chondritic precursors. The Fe/Mn difference between achondrites and chondrites is particularly significant since Fe and Mn are geochemically similar elements with similar partitioning behavior in familiar magmatic systems and are generally coupled during crystal-liquid fractionation. In contrast, however, Mn is more volatile than Fe in a nebular setting. Variation of Fe/Mn ratios based on the relative volatility of these elements in the early nebula provides a constraint for models by which the basaltic achondrites (with Fe/Mn ratios approximately = 25-50) are derived from mixtures of nebular components that were enriched in volatile components such as Mn. However, such volatile enriched components have not been identified in chondrites. When the abundance in achondrites of elements of similar volatility is examined, anomalies appear. For example, Na is massively depleted in basaltic achondrites when compared to Mn. These anomalies might be explained using current models but the alternative hypothesis, that Fe/Mn ratio is controlled not by nebular volatility constraints, but by planetary differentiation should be explored.

  11. Synthesis and studies of growth kinetics of monodispersed iron oxide nanoparticles using ferrocene as novel precursor

    NASA Astrophysics Data System (ADS)

    Bhalerao, G. M.; Sinha, A. K.; Srivastava, Himanshu; Srivastava, A. K.

    2009-05-01

    We have used ferrocene and paraffin wax as novel precursor and solvent for the growth of iron oxide nanoparticles. The proposed method of growth has several advantages over existing methods of growth using iron pentacarbonyl a precursor. Highly crystalline and monodispersed particles are obtained which assemble in two- and three-dimensional hexagonal closed packed superlattices. Growth kinetics has been studied by varying concentration of the precursor and time of growth. A phenomenological model has been proposed to explain the growth kinetics.

  12. Method to determine the sticking coefficient of precursor molecules in atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Rose, M.; Bartha, J. W.

    2009-04-01

    A method to determine the sticking coefficient of precursor molecules used in atomic layer deposition (ALD) will be introduced. The sticking coefficient is an interesting quantity for comparing different ALD processes and reactors but it cannot be observed easily. The method relies on free molecular flow in nanoscale cylindrical holes. The sticking coefficient is determined for tetrakis(dimethylamino)titanium in combination with ozone. The proposed method can be applied independent of the type of reactor, precursor delivery system and precursors.

  13. Natural attenuation of NDMA precursors in an urban, wastewater-dominated wash.

    PubMed

    Woods, Gwen C; Dickenson, Eric R V

    2016-02-01

    N-Nitrosodimethylamine (NDMA) is a disinfection by-product (DBP) that is potentially carcinogenic and has been found to occur in drinking water treatment systems impacted with treated wastewater. A major gap in NDMA research is an understanding of the persistence of wastewater-derived precursors within the natural environment. This research sought to fill this knowledge gap by surveying NDMA precursors across the length of a wastewater effluent-dominated wash. Significant precursor reduction (17%) was found to occur from introduction into the wash to a point 9 h downstream. This reduction translates into a half-life of roughly 32 h for bulk NDMA precursors. Further laboratory experiments examining rates of photolysis, biodegradation and loss to sediments, illustrated that both photolytic and biological degradation were effective removal mechanisms for NDMA precursors. Loss to sediments that were acquired from the wash did not appear to reduce NDMA precursors in the water column, although a control conducted with DI water provided evidence that significant NDMA precursors could be released from autoclaved sediments (suggesting that sorption does occur). Microbial experiments revealed that microbes associated with sediments were much more effective at degrading precursors than microbes within the water column. Overall, this study demonstrated that natural processes are capable of attenuating NDMA precursors relatively quickly within the environment, and that utilities might benefit from maximizing source water residency time in the environment, prior to introduction into treatment plants. PMID:26706247

  14. Optical Precursor with Four-Wave Mixing and Storage Based on a Cold-Atom Ensemble

    NASA Astrophysics Data System (ADS)

    Ding, Dong-Sheng; Jiang, Yun Kun; Zhang, Wei; Zhou, Zhi-Yuan; Shi, Bao-Sen; Guo, Guang-Can

    2015-03-01

    We observed optical precursors in four-wave mixing based on a cold-atom gas. Optical precursors appear at the edges of pulses of the generated optical field, and propagate through the atomic medium without absorption. Theoretical analysis suggests that these precursors correspond to high-frequency components of the signal pulse, which means the atoms cannot respond quickly to rapid changes in the electromagnetic field. In contrast, the low-frequency signal components are absorbed by the atoms during transmission. We also showed experimentally that the backward precursor can be stored using a Raman transition of the atomic ensemble and retrieved later.

  15. Precursors of Halobenzoquinones and Their Removal During Drinking Water Treatment Processes.

    PubMed

    Wang, Wei; Qian, Yichao; Jmaiff, Lindsay K; Krasner, Stuart W; Hrudey, Steve E; Li, Xing-Fang

    2015-08-18

    Halobenzoquinones (HBQs) widely occur in drinking water treatment plant (DWTP) effluents; however, HBQ precursors and their removal by treatments remain unclear. Thus, we have investigated HBQ precursors in plant influents and their removal by each treatment before chlorination in nine DWTPs. The levels of HBQ precursors were determined using formation potential (FP) tests for 2,6-dichloro-1,4-benzoquinone (DCBQ), 2,3,6-trichloro-1,4-benzoquinone (TCBQ), 2,6-dichloro-3-methyl-1,4-benzoquinone (DCMBQ), and 2,6-dibromo-1,4-benzoquinone (DBBQ). HBQ precursors were present in all plant influents. DCBQ precursors were the most abundant (DCBQ FP up to 205 ng/L). Coagulation removed dissolved organic carbon (DOC) (up to 56%) and HBQ precursors (up to 39% for DCBQ). The level of removal of DOC was significantly greater than the level of removal of HBQ FP, suggesting that organic matter removed by coagulation had a high proportion of non-HBQ-precursor material. Granular activated carbon (GAC) decreased the level of HBQ FPs by 10-20%, where DOC removal was only 0.2-4.7%, suggesting that the GAC was not in the adsorption mode and biodegradation of HBQ precursors may have been occurring. Ozonation destroyed/transformed HBQ FPs by 10-30%, whereas anthracite/sand filtration and UV irradiation appeared to have no impact. The results demonstrated that the combined treatments did not substantially reduce HBQ precursor levels in water. PMID:26196663

  16. Electron Heating, Magnetic Field Amplification, and Cosmic-Ray Precursor Length at Supernova Remnant Shocks

    NASA Astrophysics Data System (ADS)

    Laming, J. Martin; Hwang, Una; Ghavamian, Parviz; Rakowski, Cara

    2014-07-01

    We investigate the observability, by direct and indirect means, of a shock precursor arising from magnetic field amplification by cosmic rays. We estimate the depth of such a precursor under conditions of nonresonant amplification, which can provide magnetic field strengths comparable to those inferred for supernova remnants. Magnetic field generation occurs as the streaming cosmic rays induce a plasma return current, and it may be quenched by either nonresonant or resonant channels. In the case of nonresonant saturation, the cosmic rays become magnetized and amplification saturates at higher magnetic fields. The precursor can extend out to 1017-1018 cm and is potentially detectable. If resonant saturation occurs, the cosmic rays are scattered by turbulence and the precursor length will likely be much smaller. The dependence of precursor length on shock velocity has implications for electron heating. In the case of resonant saturation, this dependence is similar to that in the more familiar resonantly generated shock precursor, which when expressed in terms of the cosmic-ray diffusion coefficient kappav and shock velocity vs is kappav/vs . In the nonresonantly saturated case, the precursor length declines less quickly with increasing vs . Where precursor length proportional to 1/vs gives constant electron heating, this increased precursor length could be expected to lead to higher electron temperatures for nonresonant amplification. This should be expected at faster supernova remnant shocks than studied by previous works. Existing results and new data analysis of SN 1006 and Cas A suggest some observational support for this idea.

  17. Synthesis of stable precursor solution for MOD-processing of YBCO coated conductors

    NASA Astrophysics Data System (ADS)

    Kim, Young-Kuk; Yoo, Jaimoo; Chung, Kookchae; Ko, Jaewoong

    2006-10-01

    MOD precursor solutions for YBCO coated conductors were synthesized by either adding organic additives or substituting F-free Cu precursor for Cu-trifluoroacetate (TFA) to improve the stability of the precursor solution. The precursor solution without any significant change in the viscosity was synthesized by incorporating polyvinylpyrrolidone (PVP) and thickness of precursor film after calcination was enhanced. In addition, F-free Cu precursor was employed to synthesize the precursor solution with less fluorine content. Stable precursor solution without time-dependent viscosity degradation was obtained and the crack-free and 1.7 μm thick precursor film was formed after fast calcination at 400 °C in wet O2 atmosphere. A 0.5 μm-thick YBCO film was formed after annealing in wet Ar/O2 mixed gas and showed critical current density of 0.8 MA/cm2. Further optimization of processing conditions such as total pressure, oxygen partial pressure, annealing temperature, etc. is in progress to improve critical current. This chemical modification approach is a possible candidate for improving stability and performance of MOD-processing of YBCO coated conductor.

  18. Enantiomeric Excesses of Acid Labile Amino Acid Precursors of the Murchison Meteorite

    NASA Technical Reports Server (NTRS)

    Pizzarello, Sandra

    1998-01-01

    Amino acids present in carbonaceous chondrite are extracted in water in part as free compounds and in approximately equal part as acid labile precursors. On the assumption that they would be free of contamination, the precursors of two Murchison amino acids that have terrestrial occurrence, alanine and glutamic acid, have been targeted for analysis of their enantiomeric ratios. Pyroglutamic acid, the precursor of glutamic acid, was found with an L-enantiomeric excess comparable to that of the free acid, while alanine's precursor, N-acetyl alanine, appears approximately racemic. Also alpha-imino propioacetic acid, a proposed end product of alanine synthesis in the meteorite, was analyzed and found racemic.

  19. Contribution of N-Nitrosamines and Their Precursors to Domestic Sewage by Greywaters and Blackwaters.

    PubMed

    Zeng, Teng; Mitch, William A

    2015-11-17

    N-nitrosamines and their precursors are significant concerns for water utilities exploiting wastewater-impacted water supplies, particularly those practicing potable reuse of wastewater. Previous efforts to identify specific precursors in municipal wastewater accounting for N-nitrosamine formation have met with limited success. As an alternative, we quantified the relative importance of greywater (i.e., shower, kitchen sink, bathroom washbasin, and laundry) and blackwater (i.e., urine and feces) streams in terms of their loadings of ambient specific and total N-nitrosamines and chloramine-reactive and ozone-reactive N-nitrosamine precursors to domestic sewage. Accounting for the volume fractions of individual greywater and blackwater streams, laundry water represented the most significant source of N-nitrosamines and their precursors, followed by shower water and urine. Laundry water was particularly important for ozone-reactive N-nitrosamine precursors, accounting for ∼99% of N-nitrosodimethylamine (NDMA) precursors and ∼69% of precursors for other uncharacterized N-nitrosamines. For the other greywater streams, consumer products contributed additional N-nitrosamines and precursors, but the remarkable uniformity across different products suggested the importance of common macroconstituents. The consumption of a standard dose of the antacid ranitidine substantially increased NDMA and its chloramine-reactive precursors in urine. Nevertheless, nearly 40% of the American population would need to consume ranitidine daily to match the NDMA loadings from laundry water. PMID:26496512

  20. Novel applications of ceramic precursors -- TiN coating on alumina and functionally gradient materials

    SciTech Connect

    Seyferth, D.; Narula, C.K.; Czubarow, P.

    1996-12-31

    There are very few demonstrated applications of ceramic precursor technology. Here, the authors describe two new applications of known ceramic precursors, thin film deposition and the fabrication of functionally gradient materials (FGM). To demonstrate the thin film deposition, the authors prepared titanium nitride film on an alumina substrate using (CH{sub 3}){sub 3}SiNHTiCl{sub 3} precursor by a single dipcoat-fire cycle. The fabrication of copper and aluminum based FGMs was demonstrated using Nicalon{reg_sign} fiber polycarbosilane and poly(methylsilane) precursors as binders and in situ sources of ceramics.

  1. Formation of perfluorinated surfactants from precursors by indigenous microorganisms in groundwater.

    PubMed

    Murakami, Michio; Nishikoori, Hiroshi; Sakai, Hiroshi; Oguma, Kumiko; Takada, Hideshige; Takizawa, Satoshi

    2013-09-01

    The formation of perfluorinated surfactants (PFSs) from their precursors in waters is of concern. In this study, the formation of PFSs through biodegradation of precursors was measured in incubation tests. Indigenous microorganisms in groundwater were able to biodegrade perfluorooctane sulfonamide (FOSA) to yield perfluorooctane sulfonate (PFOS). The addition of nutrients and soil promoted the formation. A 42-d incubation test using sources of groundwater recharge showed that PFOS, perfluorooctanoate, and perfluorononanoate were significantly and remarkably (⩾1.5×) formed from precursors in street runoff through biodegradation, but not in rainwater or wastewater effluent. Significant formation of PFSs from precursors in street runoff was observed. PMID:23746363

  2. Spray dried glyceryl monooleate-magnesium trisilicate dry powder as cubic phase precursor.

    PubMed

    Shah, Manish H; Biradar, Shailesh V; Paradkar, Anant R

    2006-10-12

    Glyceryl monooleate (GMO) is a polar amphiphilic lipid, which forms different sequential lyotropic liquid crystals upon hydration. GMO has been utilized for various delivery systems and routes of administrations. Owing to sticky and waxy nature of GMO, preparation of oral solid dosage form utilizing GMO is still a challenge for pharmaceutical researchers. Therefore, the objective of the present work was to fabricate dry powder precursors using GMO, which upon hydration in situ forms cubic phase and can be wisely used for fabrication of oral solid dosage forms. In addition to this, dry powder precursor was evaluated for drug loading, in vitro release behavior and in vivo performance of model drug diclofenac sodium (DiNa). The dry powder precursor was obtained by spray-drying GMO with DiNa using magnesium trisilicate (MTS) as adsorbent. The percent drug entrapment of various batches of powder precursor was in the range of 84-93% indicating high content uniformity. SEM and image analysis showed that as the amount of MTS in powder precursor was increased, the particle size decreased. Furthermore, the viscosity of powder precursor was function of amount of MTS. The rate of water uptake of powder precursor was higher due to uniform layer of GMO on the MTS surface, which led to faster transformation of lamellar phase into cubic phase. The polarizing light microscopy confirmed that cubic phase was formed upon hydration of powder precursor. The drug released from powder precursor was initially governed by the cubic phase formed and in later stage it depends upon dynamic swelling behavior of hexagonally packed cylindrical aggregates. The drug loaded powder precursor was found to have more effective and prolonged anti-inflammatory and analgesic activity as compared to pure drug. Thus the dry powder precursor of cubic phase was prepared in which drug release was entirely governed by the mesophases formed. PMID:16846704

  3. From iron(III) precursor to magnetite and vice versa

    SciTech Connect

    Gotic, M.; Jurkin, T.; Music, S.

    2009-10-15

    The syntheses of nanosize magnetite particles by wet-chemical oxidation of Fe{sup 2+} have been extensively investigated. In the present investigation the nanosize magnetite particles were synthesised without using the Fe(II) precursor. This was achieved by {gamma}-irradiation of water-in-oil microemulsion containing only the Fe(III) precursor. The corresponding phase transformations were monitored. Microemulsions (pH {approx} 12.5) were {gamma}-irradiated at a relatively high dose rate of {approx}22 kGy/h. Upon 1 h of {gamma}-irradiation the XRD pattern of the precipitate showed goethite and unidentified low-intensity peaks. Upon 6 h of {gamma}-irradiation, reductive conditions were achieved and substoichiometric magnetite ({approx}Fe{sub 2.71}O{sub 4}) particles with insignificant amount of goethite particles found in the precipitate. Hydrated electrons (e{sub aq}{sup -}), organic radicals and hydrogen gas as radiolytic products were responsible for the reductive dissolution of iron oxide in the microemulsion and the reduction Fe{sup 3+} {yields} Fe{sup 2+}. Upon 18 h of {gamma}-irradiation the precipitate exhibited dual behaviour, it was a more oxidised product than the precipitate obtained after 6 h of {gamma}-irradiation, but it contained magnetite particles in a more reduced form ({approx}Fe{sub 2.93}O{sub 4}). It was presumed that the reduction and oxidation processes existed as concurrent competitive processes in the microemulsion. After 18 h of {gamma}-irradiation the pH of the medium shifted from the alkaline to the acidic range. The high dose rate of {approx}22 kGy/h was directly responsible for this shift to the acidic range. At a slightly acidic pH a further reduction of Fe{sup 3+} {yields} Fe{sup 2+} resulted in the formation of more stoichiometric magnetite particles, whereas the oxidation conditions in the acidic medium permitted the oxidation Fe{sup 2+} {yields} Fe{sup 3+}. The Fe{sup 3+} was much less soluble in the acidic medium and it hydrolysed and recrystallised as goethite. The {gamma}-irradiation of the microemulsion for 25 h at a lower dose rate of 16 kGy/h produced pure substoichiometric nanosize magnetite particles of about 25 nm in size and with the stoichiometry of Fe{sub 2.83}O{sub 4}.

  4. NASA Accident Precursor Analysis Handbook, Version 1.0

    NASA Technical Reports Server (NTRS)

    Groen, Frank; Everett, Chris; Hall, Anthony; Insley, Scott

    2011-01-01

    Catastrophic accidents are usually preceded by precursory events that, although observable, are not recognized as harbingers of a tragedy until after the fact. In the nuclear industry, the Three Mile Island accident was preceded by at least two events portending the potential for severe consequences from an underappreciated causal mechanism. Anomalies whose failure mechanisms were integral to the losses of Space Transportation Systems (STS) Challenger and Columbia had been occurring within the STS fleet prior to those accidents. Both the Rogers Commission Report and the Columbia Accident Investigation Board report found that processes in place at the time did not respond to the prior anomalies in a way that shed light on their true risk implications. This includes the concern that, in the words of the NASA Aerospace Safety Advisory Panel (ASAP), "no process addresses the need to update a hazard analysis when anomalies occur" At a broader level, the ASAP noted in 2007 that NASA "could better gauge the likelihood of losses by developing leading indicators, rather than continue to depend on lagging indicators". These observations suggest a need to revalidate prior assumptions and conclusions of existing safety (and reliability) analyses, as well as to consider the potential for previously unrecognized accident scenarios, when unexpected or otherwise undesired behaviors of the system are observed. This need is also discussed in NASA's system safety handbook, which advocates a view of safety assurance as driving a program to take steps that are necessary to establish and maintain a valid and credible argument for the safety of its missions. It is the premise of this handbook that making cases for safety more experience-based allows NASA to be better informed about the safety performance of its systems, and will ultimately help it to manage safety in a more effective manner. The APA process described in this handbook provides a systematic means of analyzing candidate accident precursors by evaluating anomaly occurrences for their system safety implications and, through both analytical and deliberative methods used to project to other circumstances, identifying those that portend more serious consequences to come if effective corrective action is not taken. APA builds upon existing safety analysis processes currently in practice within NASA, leveraging their results to provide an improved understanding of overall system risk. As such, APA represents an important dimension of safety evaluation; as operational experience is acquired, precursor information is generated such that it can be fed back into system safety analyses to risk-inform safety improvements. Importantly, APA utilizes anomaly data to predict risk whereas standard reliability and PRA approaches utilize failure data which often is limited and rare.

  5. An ESA precursor mission to human exploration of the Moon

    NASA Astrophysics Data System (ADS)

    Carpenter, James; Fisackerly, Richard; Houdou, Berengere; Pradier, Alain; de Rossa, Diego; Vanoutryve, Benjamine; Jojaghaian, Aliac; Espinasse, Sylvie; Gardini, Bruno

    The coming decades will once again see humans on the surface of the Moon. Unlike the Apollo missions of the 1960s this new lunar exploration will be an international effort, with long duration missions and a goal to pave the way for further human expansion into the solar system. Ensuring the success and sustainability of this exploration poses significant challenges for all involved. ESA is currently preparing its first contribution to this international lunar exploration effort; a lunar lander mission, which will be a precursor to a future, Ariane V launched, ESA cargo and logistics capability to the Moon. The precursor mission will demonstrate soft precision landing with hazard avoidance capabilities, which will be required by a future cargo lander. In addition the mission can be applied as a preparation for future human exploration activities and help to ensure the sustainability of future exploration efforts. Activities have included Phase A and B1 mission design studies and technology development activities (both reported in another paper) and the definition of mission objectives and a model payload. The mission objectives have been derived by the Lunar Exploration Definition Team, a group derived of European specialists in various areas of exploration related science and technology, supported by ESA. Major inputs to the definition process were the 195 responses received to a request for information for potential payload contributions to the mission. The group was tasked with establishing how such a mission could best prepare for future human exploration. It was determined that the mission's goal should be to enable sustainable exploration and objectives were identified within a number of themes: health, habitation, resources, mobility and scientific preparations for future human activities. Investigations seek to characterise the lunar environment (e.g. radiation, dust etc.) and its effects and the properties of a landing site (potential resources, geological context) as relevant to these areas and ensure the maturation of key technologies. In this paper we discuss the objectives for the lunar lander mission and describe the model payload and the approach to selection and implementation of a final payload for the mission.

  6. An ESA precursor mission to human exploration of the Moon

    NASA Astrophysics Data System (ADS)

    Carpenter, James; Fisackerly, Richard; Houdou, Berengere; Pradier, Alain; de Rossa, Diego; Vanoutryve, Benjamin; Jojaghaian, Aliac; Espinasse, Sylvie; Gardini, Bruno

    2010-05-01

    The coming decades will once again see humans on the surface of the Moon. Unlike the Apollo missions of the 1960s this new lunar exploration will be an international effort, with long duration missions and a goal to pave the way for further human expansion into the solar system. Ensuring the success and sustainability of this exploration poses significant challenges for all involved. ESA is currently preparing its first contribution to this international lunar exploration effort; a lunar lander mission, which will be a precursor to a future, Ariane V launched, ESA cargo and logistics capability to the Moon. The precursor mission will demonstrate soft precision landing with hazard avoidance capabilities, which will be required by a future cargo lander. In addition the mission can be applied as a preparation for future human exploration activities and help to ensure the sustainability of future exploration efforts. Activities have included Phase A and B1 mission design studies and technology development activities (both reported in another paper) and the definition of mission objectives and a model payload. The mission objectives have been derived by the Lunar Exploration Definition Team, a group derived of European specialists in various areas of exploration related science and technology, supported by ESA. Major inputs to the definition process were the 195 responses received to a request for information for potential payload contributions to the mission. The group was tasked with establishing how such a mission could best prepare for future human exploration. It was determined that the mission's goal should be to enable sustainable exploration and objectives were identified within a number of themes: health, habitation, resources, mobility and scientific preparations for future human activities. Investigations seek to characterise the lunar environment (e.g. radiation, dust etc.) and its effects and the properties of a landing site (potential resources, geological context) as relevant to these areas and ensure the maturation of key technologies. In this paper we discuss the objectives for the lunar lander mission and describe the model payload and the approach to selection and implementation of a final payload for the mission.

  7. Precursors for the synthesis of citrulline in mice fed arginine free diets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dietary arginine (Arg) is the main dietary precursor for citrulline (Cit) synthesis. To test the hypothesis that the contribution of dietary proline (Pro) and glutamine (Gln) increases during the feeding of an Arg free diet, rates of appearance (Ra) and precursor-intermediate-product relationships w...

  8. Validation of Measures of Biosocial Precursors to Borderline Personality Disorder: Childhood Emotional Vulnerability and Environmental Invalidation

    ERIC Educational Resources Information Center

    Sauer, Shannon E.; Baer, Ruth A.

    2010-01-01

    Linehan's biosocial theory suggests that borderline personality disorder (BPD) results from a transaction of two childhood precursors: emotional vulnerability and an invalidating environment. Until recently, few empirical studies have explored relationships between these theoretical precursors and symptoms of the disorder. Psychometrically sound…

  9. Effects of Peer Mediation on Preschoolers' Compliance and Compliance Precursors

    ERIC Educational Resources Information Center

    Beaulieu, Lauren; Hanley, Gregory P.; Roberson, Aleasha A.

    2013-01-01

    We used a multiple baseline design across participants to evaluate the effects of teaching 4 typically developing preschoolers to attend to their names and to a group call (referred to as "precursors") on their compliance with typical classroom instructions. We then measured the extent to which the effects on both precursors and…

  10. Development of a continuous spinning process for producing silicon carbide - silicon nitride precursor fibers

    NASA Technical Reports Server (NTRS)

    1985-01-01

    An apparatus was designed for the continuous production of silicon carbide - silicon nitride precursor fibers. The precursor polymer can be fiberized, crosslined and pyrolyzed. The product is a metallic black fiber with the composition of the type C sub x Si sub y n sub z. Little, other than the tensile strength and modulus of elasticity, is known of the physical properties.

  11. Bound Volatile Precursors in Genotypes in the Pedigree of 'Marion' Blackberry (Rubus Sp.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Glycosidically bound volatiles and precursors in genotypes representing the pedigree for 'Marion' blackberry were investigated over two growing seasons. The volatile precursors were isolated using a C18 solid-phase extraction column. After enzymatic hydrolysis, the released volatiles were analyzed u...

  12. Influence of calcium precursors on the morphology and crystallinity of sol gel-derived hydroxyapatite nanoparticles

    NASA Astrophysics Data System (ADS)

    Vijayalakshmi Natarajan, U.; Rajeswari, S.

    2008-10-01

    Nanosized hydroxyapatite (HAP) particles were prepared by sol-gel method from the water-based solution of calcium and phosphorus precursor. In this study, two calcium precursors such as calcium nitrate tetrahydrate and calcium acetate were chosen as calcium precursors. The influence of aging period, pH, viscosity and sintering temperature on crystallinity and morphology of the HAP particles were investigated for the two calcium precursors with triethyl phosphate precursor. The morphology of nano-HAP towards phosphorous precursor was dependent on the type of calcium precursor used. The HAP prepared from calcium nitrate and triethyl phosphate was spherically shaped whereas the one from calcium acetate was found to be fibrous in structure. Both HAPs were stable up to 1200 °C and their crystallinity increased with respect to the sintering temperature. The obtained sample was characterized through X-ray diffraction (XRD), P 31 nuclear magnetic resonance (NMR), scanning electronic microscopy (SEM) and TEM analysis. The sol derived from the optimized aging period for the two different calcium precursors was coated on 316L stainless-steel (SS) implant and its corrosion resistivity during long-term implantation was studied by cyclic polarization in Ringer's solution. Both HAPs have their own desirable qualities and were found to be corrosion resistive.

  13. Biochemical removal of HAP precursors from coal. Technical progress report, October--December 1995

    SciTech Connect

    1995-12-31

    During this first quarter, the project management plan was submitted and approved by DOE. A coal pyrite oxidizing bacterial population was adapted to Pittsburgh coal and was used to inoculate the first shake flask tests for hazardous air pollutants (HAP) precursor removal. Analyses were conducted on NIST 1632b, a bituminous coal certified for many of the inorganic HAP precursors.

  14. The Use of Social Stories To Reduce Precursors to Tantrum Behavior in a Student with Autism.

    ERIC Educational Resources Information Center

    Kuttler, Shari; Myles, Brenda Smith; Carlson, Judith K.

    1998-01-01

    A study involving a 12-year-old boy with autism, Fragile X syndrome, and intermittent explosive disorder, analyzed the effects of social stories in reducing precursors to tantrum behavior during morning work time and lunchtime. Results indicated a decrease in precursors to tantrums when the social stories were available to the student. (Author/CR)

  15. Solution Deposited Precursors and Rapid Optical Processing Used in the Production of CIGS Solar Cells

    SciTech Connect

    Hersh, P. A.; Curtis, C. J.; Van Hest, M. F. A. M.; Habas, S. E.; Miedaner, A.; Ginley, D. S.; Stanbery, B. J.

    2011-01-01

    In this paper we use the combination of solution deposited liquid precursors and rapid optical processing (ROP) to make CIGS. The ROP process takes less than 1 minute of heating to convert the precursor stack to CIGS. Device made with ROP rival performance of device processed using field assisted simultaneous synthesis and transfer FASST{reg_sign} processing.

  16. Vaporization of a mixed precursors in chemical vapor deposition for YBCO films

    NASA Technical Reports Server (NTRS)

    Zhou, Gang; Meng, Guangyao; Schneider, Roger L.; Sarma, Bimal K.; Levy, Moises

    1995-01-01

    Single phase YBa2Cu3O7-delta thin films with T(c) values around 90 K are readily obtained by using a single source chemical vapor deposition technique with a normal precursor mass transport. The quality of the films is controlled by adjusting the carrier gas flow rate and the precursor feed rate.

  17. Modeling precursor diffusion and reaction of atomic layer deposition in porous structures

    SciTech Connect

    Keuter, Thomas Menzler, Norbert Heribert; Mauer, Georg; Vondahlen, Frank; Vaßen, Robert; Buchkremer, Hans Peter

    2015-01-01

    Atomic layer deposition (ALD) is a technique for depositing thin films of materials with a precise thickness control and uniformity using the self-limitation of the underlying reactions. Usually, it is difficult to predict the result of the ALD process for given external parameters, e.g., the precursor exposure time or the size of the precursor molecules. Therefore, a deeper insight into ALD by modeling the process is needed to improve process control and to achieve more economical coatings. In this paper, a detailed, microscopic approach based on the model developed by Yanguas-Gil and Elam is presented and additionally compared with the experiment. Precursor diffusion and second-order reaction kinetics are combined to identify the influence of the porous substrate's microstructural parameters and the influence of precursor properties on the coating. The thickness of the deposited film is calculated for different depths inside the porous structure in relation to the precursor exposure time, the precursor vapor pressure, and other parameters. Good agreement with experimental results was obtained for ALD zirconiumdioxide (ZrO{sub 2}) films using the precursors tetrakis(ethylmethylamido)zirconium and O{sub 2}. The derivation can be adjusted to describe other features of ALD processes, e.g., precursor and reactive site losses, different growth modes, pore size reduction, and surface diffusion.

  18. Testing the Predictors of Boredom at School: Development and Validation of the Precursors to Boredom Scales

    ERIC Educational Resources Information Center

    Daschmann, Elena C.; Goetz, Thomas; Stupnisky, Robert H.

    2011-01-01

    Background: Boredom has been found to be an important emotion for students' learning processes and achievement outcomes; however, the precursors of this emotion remain largely unexplored. Aim: In the current study, scales assessing the precursors to boredom in academic achievement settings were developed and tested. Sample: Participants were 1,380…

  19. Validation of Measures of Biosocial Precursors to Borderline Personality Disorder: Childhood Emotional Vulnerability and Environmental Invalidation

    ERIC Educational Resources Information Center

    Sauer, Shannon E.; Baer, Ruth A.

    2010-01-01

    Linehan's biosocial theory suggests that borderline personality disorder (BPD) results from a transaction of two childhood precursors: emotional vulnerability and an invalidating environment. Until recently, few empirical studies have explored relationships between these theoretical precursors and symptoms of the disorder. Psychometrically sound

  20. Progressing from Identification and Functional Analysis of Precursor Behavior to Treatment of Self-Injurious Behavior

    ERIC Educational Resources Information Center

    Dracobly, Joseph D.; Smith, Richard G.

    2012-01-01

    This multiple-study experiment evaluated the utility of assessing and treating severe self-injurious behavior (SIB) based on the outcomes of a functional analysis of precursor behavior. In Study 1, a precursor to SIB was identified using descriptive assessment and conditional probability analyses. In Study 2, a functional analysis of precursor…