Sample records for gamma-hydroxybutyrate ghb precursors

  1. GHB - Gamma-Hydroxybutyric Acid

    MedlinePLUS

    ... Ribbon Week DEA Red Ribbon Week Patch Program GHB - Gamma-Hydroxybutyric Acid Last Updated: Monday, August 4, ... in water, juice, or alcohol. In liquid form, GHB is clear and colorless and slightly salty in ...

  2. Gamma Hydroxybutyric Acid (GHB) Intoxication

    Microsoft Academic Search

    Phillip E. Mason; William P. Kerns II

    2002-01-01

    Gamma-aminobutyric acid (GABA) was discovered as the predominant inhibitory central nervous sys- tem (CNS) neurotransmitter in 1956. This prompted a search for a GABA analog that would cross the blood-brain barrier for possible therapeutic use. During this search, gamma-hydroxybutyric acid (GHB) was found in the brain and subsequently synthesized in the laboratory in 1964. 1,2 Since its discovery, GHB has

  3. 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 ...

  4. Clinical features and management of gamma-hydroxybutyrate (GHB) withdrawal: a review

    Microsoft Academic Search

    Michael McDonough; Noel Kennedy; Anthony Glasper; Jenny Bearn

    2004-01-01

    Aim: To examine the clinical course of gamma-hydroxybutyrate (GHB) withdrawal and generate management guidelines. Design: Review and analysis of all published reports of GHB or GHB precursor withdrawal identified from electronic searches. Findings: In total, 38 cases of GHB (n=28) or GHB precursor (n=10) withdrawal were identified, 36 of which were from the US. A rapidly deteriorating course into delirium

  5. 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…

  6. 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

  7. Gamma Hydroxybutyrate (GHB) and Gamma Butyrolactone (GBL) Withdrawal: Five Case Studies

    Microsoft Academic Search

    Charles H. McDaniel; Karen A. Miotto

    2001-01-01

    There is little medical information available about gamma- hydroxybutyrate (GHB) or gamma-butyrolactone (GBL) dependence or withdrawal. In this study the authors treated and reviewed multiple cases of GHB and GBL withdrawal in high-dose users. Five patients during nine hospitalizations were treated for GHB or GBL withdrawal. The authors describe a spectrum of GHB or GBL withdrawal from mild to severe

  8. Gamma hydroxybutyric acid (GHB) concentrations in humans and factors affecting endogenous production

    Microsoft Academic Search

    Simon P Elliott

    2003-01-01

    The endogenous nature of the drug of abuse gamma hydroxybutyric acid (GHB) has caused various interpretative problems for toxicologists. In order to obtain data for the presence of endogenous GHB in humans and to investigate any factors that may affect this, a volunteer study was undertaken. The GHB concentrations in 119 urine specimens from GHB-free subjects and 25 urine specimens

  9. Effects of gamma-hydroxybutyric acid (GHB) in opioid-dependent patients

    Microsoft Academic Search

    Marc I. Rosen; H. Rowland Pearsall; Scott W. Woods; Thomas R. Kosten

    1997-01-01

    Gamma-hydroxybutyric acid (GHB) is a GABA metabolite used clinically for sleep induction. The abuse liability of GHB is controversial. As part of a study of the effect of GHB pretreatment on naloxone-precipitated opiate withdrawal, eight opioid-stabilized subjects received a balanced, randomized, double-blind sequence of oral placebo, GHB 15 mg\\/kg and 30 mg\\/kg. GHB had no consistent physiological effects. After GHB

  10. 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 ?-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

  11. Involvement of gamma-hydroxybutyrate (GHB) and GABA-B receptors in the acute behavioral effects of GHB in baboons

    Microsoft Academic Search

    Amy K. Goodwin; Wolfgang Froestl; Elise M. Weerts

    2005-01-01

    Rationale: Gamma-hydroxybutyrate (GHB) is used for the treatment of narcolepsy, but it is also a drug of abuse. The behavioral pharmacology of GHB is not well defined. Objectives: The current study was conducted to characterize the behavioral effects of a range of GHB doses in baboons (N=4) and to evaluate whether a GABA-B re- ceptor antagonist and a GHB receptor

  12. GC–MS determination of gamma-hydroxybutyric acid (GHB) in blood

    Microsoft Academic Search

    Albert A. Elian

    2001-01-01

    A sensitive and specific gas chromatography–mass spectrometer (GC–MS) method using selective ion monitoring (SIM) has been developed for the quantification of gamma-hydroxybutyric acid (GHB) in blood. This method uses liquid–liquid extraction and disilyl-derivatization, without conversion to the gamma-butyrolactone (GBL), followed by GC–MS analysis using GHB-d6 as the internal standard. The method was linear from 0.1 to 20mg\\/dl, and the limit

  13. Determination of endogenous gamma-hydroxybutyric acid (GHB) levels in antemortem urine and blood

    Microsoft Academic Search

    Albert A. Elian

    2002-01-01

    Gamma-hydroxybutyric acid’s (GHB’s) natural presence in the body has made the interpretation of its levels a challenging task for the forensic toxicologist. This study was designed to measure endogenous GHB levels in antemortem urine and blood samples. The range detected in urine was from 34 to 575?g\\/dl and in blood from 17 to 151?g\\/dl. The results indicate that the concentration

  14. Use, function, and subjective experiences of gamma-hydroxybutyrate (GHB)

    Microsoft Academic Search

    Harry R. Sumnall; Kerry Woolfall; Sara Edwards; Jon C. Cole; Caryl M. Beynon

    2008-01-01

    Self-reported use of ?-hydroxybutyrate (GHB) among clubbers has increased over the last decade, and is often reported in the scientific literature in association with negative events such as amnesia, overdose, and use in drug facilitated sexual assault. However, there has been relatively little work investigating the phenomenology of GHB intoxication, and the reasons underlying use. In this study, 189 individuals

  15. Narcolepsy and effectiveness of gamma-hydroxybutyrate (GHB): A systematic review and meta-analysis of randomized controlled trials

    Microsoft Academic Search

    Rafael Boscolo-Berto; Guido Viel; Sara Montagnese; Daniella I. Raduazzo; Santo D. Ferrara; Yves Dauvilliers

    2012-01-01

    Objectives: Gamma-hydroxybutyrate (GHB) is currently authorized by the European Medicines Agency (EMA) to treat narcolepsy with cataplexy in adults, and by the Food and Drug Administration (FDA) to treat cataplexy in patients with narcolepsy, with an expanded indication for the treatment of excessive daytime sleepiness. This study meta-analyses and reviews the effectiveness of GHB on the clinical features of narcolepsy

  16. Anxiogenic-like effects of gamma-hydroxybutyric acid (GHB) in mice tested in the light-dark box

    Microsoft Academic Search

    José Francisco Navarro; Guadalupe Dávila; Carmen Pedraza; Jorge L. Arias

    Gamma-hydroxybutyric acid (GHB) is a drug with abuse potential, popularly known as «liquid ecsta- sy». It is an endogenous compound of the mammalian brain which satisfies many of the criteria for consideration as a neurotransmitter or neuromodulator. In this study, the effects of acute administration of GHB (40, 80 and 120 mg\\/kg, ip) on anxiety, tested in the light\\/dark box,

  17. Coma and respiratory depression following the ingestion of GHB and its precursors: Three cases 1 1 Selected Topics: Toxicology is coordinated by Kenneth Kulig, MD, of Denver, Colorado

    Microsoft Academic Search

    Marianne Ingels; Cyrus Rangan; Joseph Bellezzo; Richard F Clark

    2000-01-01

    Gamma hydroxybutyrate (GHB) is a product of the metabolism of both gamma butyrolactone (GBL) and 1,4-butanediol (1,4-BD). Gamma hydroxybutyrate (GHB) is an illegal agent that causes central nervous system depression. Chemical precursors of GHB, such as GBL and 1,4-BD, have been available for purchase from many health food stores and Internet websites for mood-enhancement, sleep-induction, and stimulation of growth hormone

  18. A case of withdrawal from the GHB precursors gamma-butyrolactone and 1,4-butanediol

    Microsoft Academic Search

    Aaron B Schneir; Binh T Ly; Richard F Clark

    2001-01-01

    We describe a case of withdrawal from the gamma hydroxybutyric acid (GHB) precursors gamma butyrolactone and 1,4-butanediol. Symptoms included visual hallucinations, tachycardia, tremor, nystagmus, and diaphoresis. Administration of benzodiazepines and phenobarbital successfully treated the withdrawal symptoms. As predicted from the metabolism of gamma butyrolactone and 1,4-butanediol to GHB, the symptoms were nearly identical to those reported from GHB withdrawal. Because

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

    PubMed

    Johansson, Jenny; Grönbladh, 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

  20. Keywords: 1,4-butanediol, gamma-hydroxybutyrate, poisoning, toy Notes: The information in this study was presented previously in the following venues: Western Regional Society for Academic Emer-

    E-print Network

    Nizkorodov, Sergey

    contained 1,4-butanediol (1,4-BD), a precursor to gamma-hydroxybutyrate (GHB), rather than the intended been completely replaced with a substitute that is metabolized into GHB after inges- tion. Reports in the Australian and American media [2,5­7]. Gamma- hydroxybutyrate (GHB) was detected in biologic samples from

  1. Endogenous gamma-hydroxybutyric acid (GHB) concentrations in post-mortem specimens and further recommendation for interpretative cut-offs.

    PubMed

    Andresen-Streichert, Hilke; Jensen, P; Kietzerow, J; Schrot, M; Wilke, N; Vettorazzi, E; Mueller, A; Iwersen-Bergmann, S

    2015-01-01

    When interpreting gamma-hydroxybutyric acid (GHB) concentrations in post-mortem specimens, a possible increase in GHB concentrations because of post-mortem generation must be considered. In this study, endogenous GHB concentrations in post-mortem biological fluids were investigated. Additionally, we review post-mortem GHB concentrations already published in the literature. Heart and peripheral blood samples, cerebrospinal fluid, urine, and vitreous humor were collected from 64 autopsies in subjects where the cause of death excluded GHB exposure. Sample analysis was carried out either on the day of autopsy or later after immediate freezing and storage at -20 °C. GHB concentrations in venous blood samples (n?=?61) were <0.6-28.7 mg/L (mean 11.9 mg/L; median 10.6 mg/L), <0.6-65.3 mg/L (mean 15.2 mg/L; median 12.8 mg/L) in heart blood (n?=?56), <0.6-25.1 mg/L (mean 6.0 mg/L; median 3.8 mg/L) in urine (n?=?50), <0.6-39.0 mg/L (mean 9.6 mg/L; median 7.5 mg/L), in vitreous humor (n?=?54), and <0.6-24.0 mg/L (mean 4.2 mg/L; median 3.2 mg/L) in cerebrospinal fluid (n?=?52). There was no significant difference between GHB concentrations in cases where there were signs of beginning putrefaction at the time of autopsy (n?=?9) and cases without obvious signs of putrefaction. In one case with advanced putrefaction, the GHB concentration in venous blood was 32.7 mg/L. In conclusion, for post-mortem venous blood, urine, and cerebrospinal fluid, an interpretative cut-off of 30 mg/L for GHB concentrations is suggested in cases where GHB analysis is conducted on the day of sample collection at autopsy or if samples have been stored at -20 °C immediately after collection. PMID:25084768

  2. 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 ?-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. Post mortem concentrations of endogenous gamma hydroxybutyric acid (GHB) and in vitro formation in stored blood and urine samples.

    PubMed

    Busardò, Francesco Paolo; Bertol, Elisabetta; Vaiano, Fabio; Baglio, Giovanni; Montana, Angelo; Barbera, Nunziata; Zaami, Simona; Romano, Guido

    2014-10-01

    Gamma-hydroxybutyrate (GHB) is a central nervous system depressant, primarily used as a recreational drug of abuse with numerous names. It has also been involved in various instances of drug-facilitated sexual assault due to its potential incapacitating effects. The first aim of this paper is to measure the post-mortem concentration of endogenous GHB in whole blood and urine samples of 30 GHB free-users, who have been divided according to the post-mortem interval (PMI) in three groups (first group: 24-36h; second group: 37-72h; third group: 73-192h), trying to evaluate the role of PMI in affecting post mortem levels. Second, the Authors have evaluated the new formation of GHB in vitro in blood and urine samples of the three groups, which have been stored at -20°C, 4°C and 20°C over a period of one month. The concentrations were measured by GC-MS after liquid-liquid extraction according to the method validated and published by Elliot (For. Sci. Int., 2003). For urine samples, GHB concentrations were creatinine-normalized. In the first group the GHB mean concentration measured after autopsy was: 2.14mg/L (range 0.54-3.21mg/L) in blood and 3.90mg/g (range 0.60-4.81mg/g) in urine; in the second group it was: 5.13mg/L (range 1.11-9.60mg/L) in blood and 3.93mg/g (range 0.91-7.25mg/g) in urine; in the third group it was: 11.8mg/L (range 3.95-24.12mg/L) in blood and 9.83mg/g (range 3.67-21.90mg/g) in urine. The results obtained in blood and urine samples showed a statistically significant difference among groups (p<0.001) in the first analysis performed immediately after autopsy. Throughout the period of investigation up to 4 weeks, the comparison of storage temperatures within each group showed in blood and urine samples a mean difference at 20°C compared to -20°C not statistically significant at the 10% level. These findings allow us to affirm that the PMI strongly affects the post mortem production of GHB in blood and urine samples. Regarding the new formation of GHB in vitro both in blood and urine samples of the three groups, which have been stored at -20°C, 4°C and 20°C over a period of one month, although there was no significant increases of GHB levels throughout the period of investigation, the lowest increases were found both in blood and urine at -20°C, therefore we recommend the latter as optimal storage temperature. PMID:25123534

  4. 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

  5. Discrimination of gamma-hydroxybutyrate and ethanol administered separately and as a mixture in rats

    Microsoft Academic Search

    Brian R. Metcalf; Jeanne M. Stahl; Joseph D. Allen; Dedra R. Woolfolk; Paul L. Soto

    2001-01-01

    The physiological effects of gamma-hydroxybutyrate (GHB) are complex and not yet clearly defined. GHB has been labeled as a recreational drug and is reported to be frequently coabused with ethanol (ETH). Other studies have yielded discrepant results as to the interaction between GHB and ETH. Thus, the present study investigated extensively the discriminative stimulus of GHB and ETH and a

  6. GC/MS profiling of gamma-hydroxybutyrate and precursors in various animal tissues using automatic solid-phase extraction. Preliminary investigations of its potential interest in postmortem interval determination.

    PubMed

    Richard, Damien; Ling, Bing; Authier, Nicolas; Faict, Thierry W; Eschalier, Alain; Coudoré, François

    2005-03-01

    To quantify gamma-hydroxybutyrate (GHB) and its physiological metabolites, gamma-aminobutyric acid (GABA), 1,4-butanediol (1,4-BD), and gamma-butyrolactone (GBL) in various animal tissues (kidney, muscle, heart, liver, blood, brain cortex, thalamus, hypothalamus, hippocampus, or pons), an original gas chromatographic/mass spectrometric method with a automated solid-phase extraction by Oasis MCX cartridges on a Gilson Aspec Xli was developed. Using such apparatus allowed the limit of detection (LOD) of target compounds to be significantly lowered (LOD: 0.027, 0.025, and 5.7 microg/mL for GHB, 1,4-BD, and GABA, respectively, in 200 microL or microg of sample). After validation of each analytical step, the satisfactory performances of the apparatus in conjunction with the rapidity and ease of the extraction step make it suitable for simultaneous assay of GHB, 1,4-BD, GBL, and GABA. The method was used to test the correlation between GHB levels in tissues obtained at different times after death of male Sprague-Dawley rats and the postmortem interval. Preliminary results show a linear increase of GHB levels in relation to time of death in thoracic blood and central nervous system of animals kept at 15 and 20 degrees C. PMID:15732918

  7. Severe gamma-hydroxybutyrate withdrawal: a case report and literature review

    Microsoft Academic Search

    Kathryn Craig; Hernan F Gomez; John L McManus; Theodore C Bania

    2000-01-01

    We report a case of gamma-hydroxybutyrate (GHB) withdrawal resulting in severe agitation, mental status changes, elevated blood pressure, and tachycardia hours after stopping chronic use of GHB. The patient admitted to substantial GHB abuse on a daily basis for 2.5 years. Previous attempts at cessation reportedly resulted in diaphoresis, tremors, and agitation. The patient’s symptoms, negative polypharmacy history, and negative

  8. The Effect of Gamma-Hydroxybutyric Acid on Naloxone-Precipitated Opiate Withdrawal

    Microsoft Academic Search

    Marc I Rosen; H Rowland Pearsall; Scott W Woods; Thomas R Kosten

    1996-01-01

    Because gamma-hydroxybutyric acid (GHB), a GABA metabolite, attenuated spontaneous opiate withdrawal in a prior study, we studied GHB's effect on naloxone-precipitated opiate withdrawal. Eight opiate-dependent inpatients were stabilized on the opioid levorphanol, 18 mg daily. After an initial acclimatization challenge, subjects underwent three double-blind challenges on consecutive days. Pretreatment in a balanced randomization was with either placebo, GHB, 15 mg\\/kg,

  9. Contribution of GABA A and GABA B Receptors to the Discriminative Stimulus Produced by Gamma-Hydroxybutyric Acid

    Microsoft Academic Search

    Carla Lobina; Roberta Agabio; Roberta Reali; Gian Luigi Gessa; Giancarlo Colombo

    1999-01-01

    The present study examined the involvement of GABAA and GABAB receptors in the discriminative stimulus effects of gamma-hydroxybutyric acid (GHB). Rats were trained to discriminate either 300 or 700 mg\\/kg GHB IG from water using a T-maze, food-reinforced drug-discrimination procedure. The direct GABAB agonist, baclofen, substituted completely for both training doses of GHB; its potency to substitute for GHB increased

  10. GHB use among gay and bisexual men

    Microsoft Academic Search

    Perry N. Halkitis; Joseph J. Palamar

    2006-01-01

    The recreational use of gamma-hydroxybutyrate (GHB) has been relatively understudied, despite its popularity in gay communities. We examined the use of GHB in a sample of 450 club drug using gay and bisexual men. Of these, 29% indicated use of the substance in the recent past. GHB users were similar to those in the sample who reported no use along

  11. GHB, GBL and 1,4-BD addiction.

    PubMed

    Brunt, Tibor M; van Amsterdam, Jan G C; van den Brink, Wim

    2014-01-01

    A growing body of evidence shows that gamma-hydroxybutyric acid (GHB) is an addictive substance. Its precursors gammabutyrolactone (GBL) and 1,4-butanediol (1,4-BD) show the same properties and may pose even more risks due to different pharmacokinetics. There are indications that problematic GHB use is increasing in the European Union. This review investigates the existing literature on the neurochemistry of GHB and its precursors, their acute toxicity, addiction potential and withdrawal, the proposed molecular mechanism underlying addiction and the treatment of withdrawal and addiction. Current evidence shows that GHB and its precursors are highly addictive, both in humans and animals, probably through a GABAB receptor related mechanism. Severity of withdrawal symptoms can be considered as a medical emergency. Recent studies suggest that benzodiazepines are not very effective, showing a high treatment resistance, whereas detoxification with pharmaceutical GHB proved to be successful. However, relapse in GHB use is frequent and more research is warranted on relapse prevention. This might aid medical practitioners in the field and improve general understanding of the severity of addiction to GHB, GBL and 1,4-BD. PMID:24001290

  12. GHB use among Australians: characteristics, use patterns and associated harm

    Microsoft Academic Search

    Louisa Degenhardt; Shane Darke; Paul Dillon

    2002-01-01

    The aim of this study was to examine the characteristics of gamma-hydroxybutyrate (GHB) users, their GHB and other drug use patterns, and the harms associated with GHB use. Seventy-six GHB users were recruited and administered a structured interview on GHB use and related harms. GHB users appeared to be a stable, highly educated and well-functioning group. They had had extensive

  13. GHB: An Important Pharmacologic and Clinical Update

    Microsoft Academic Search

    Michael S. Okun; Lisa A. Boothby; Richard B. Bartfield; Paul L. Doering

    2001-01-01

    Gamma-hydroxybutyrate (GHB) intoxica- tion is a significant cause of morbidity and mortality in patients taking the drug for recreational purposes. Due to the recent increase in emergency room visits, hospi- tal admissions, and deaths, it has become necessary to re-examine the pharmacology, pharmacokinetics, phar- macodynamics, clinical manifestations, and potential adverse effects associated with GHB use. We present an important pharmacologic

  14. 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…

  15. GHB Depresses Fast Excitatory and Inhibitory Synaptic Transmission via GABAB Receptors in Mouse Neocortical Neurons

    Microsoft Academic Search

    Kimmo Jensen; Istvan Mody

    2001-01-01

    Gamma-hydroxybutyrate (GHB) is a drug of abuse which induces sedation and euphoria. However, overdoses can severely depress the level of consciousness or can be fatal especially when combined with other substances. Studies have suggested that the GHB-effects are mediated via actions on thalamocortical pathways and local neocortical circuits, although the effect of GHB at the level of single neocortical neurons

  16. A qualitative analysis of GHB use among gay men: Reasons for use despite potential adverse outcomes

    Microsoft Academic Search

    Joseph J. Palamar; Perry N. Halkitis

    2006-01-01

    This paper examines the use of gamma-hydroxybutyrate (GHB) among a sample of gay men in New York City, who identify GHB as their most frequently used club drug. The sample was drawn from a larger longitudinal investigation of club drug using men. Thematic analysis yielded findings regarding perceived stigma for GHB use, tolerance of potential adverse side effects, and reasons

  17. GHB: a new and novel drug of abuse

    Microsoft Academic Search

    Katherine L. Nicholson; Robert L. Balster

    2001-01-01

    There has been increasing attention in the United States to problems of abuse of gamma-hydroxybutyrate (GHB), with some evidence for problems in other parts of the world as well. In vitro and animal research show that, while GHB shares some properties with abused central nervous system depressant drugs, it has unique aspects of its pharmacology as well, including actions at

  18. Acute poisoning from gamma-hydroxybutyrate in California.

    PubMed Central

    Chin, M. Y.; Kreutzer, R. A.; Dyer, J. E.

    1992-01-01

    We report a series of 5 representative patients in California who experienced adverse reactions from the illicitly marketed substance gamma-hydroxybutyrate (GHB). The drug is a putative neurotransmitter marketed as a growth hormone releaser for bodybuilders. The most commonly reported symptoms included abrupt drowsiness, dizziness, and a "high". Other effects were headache, nausea, vomiting, myoclonic jerking, and short-term coma. There have been no reported deaths. If product use is discontinued, full recovery with no long-term side effects is universal. No clear dose-response effect was observed; this may be attributable to differences in susceptibility, wide variations in doses taken by the same person, or the coingestion of other substances. Case interviews confirm that, despite being banned by the US Food and Drug Administration, GHB is still widely available in the underground drug market. Athletes and bodybuilders may take drugs for which there are claims of improved performance or body image. Physicians should be alert for signs of GHB poisoning in emergency department and clinic patients. PMID:1574880

  19. Gamma-hydroxybutyrate reduces GABA(A)-mediated inhibitory postsynaptic potentials in the CA1 region of hippocampus.

    PubMed

    Cammalleri, Maurizio; Brancucci, Alfredo; Berton, Fulvia; Loche, Antonella; Gessa, Gian Luigi; Francesconi, Walter

    2002-12-01

    Gamma-hydroxybutyric acid (GHB) is a psychoactive drug and a putative neurotransmitter, derived from gamma-aminobutyric acid (GABA). At micromolar concentrations GHB binds to specific high and low affinity binding sites present in discrete areas of the brain, while at millimolar concentrations GHB also binds to GABA(B) receptors. Previous studies indicated that GHB inhibits both NMDA and AMPA receptor mediated excitatory postsynaptic potentials in hippocampal CA1 pyramidal neurons. This action of GHB occurs in the presence of GABA(B) blockade and is antagonized by NCS-382, a specific GHB receptor antagonist, suggesting that it is mediated by GHB receptors. In the present study, we have investigated the effect of GHB on GABA(A) mediated inhibitory postsynaptic potentials (GABA(A)-IPSP) elicited in CA1 hippocampal pyramidal neurons by stimulation of Schaffer collateral-commissural fibers. We observed that GHB inhibited GABA(A)-IPSPs by about 40% at concentrations of 300-600 microM. GHB inhibition was blocked by NCS-382 (500 microM), which per se failed to modify GABA(A)-IPSPs. Moreover, GHB failed to modify cell membrane depolarization induced by the brief pressure application of GABA in the presence of tetrodotoxin (TTX), indicating that GHB does not inhibit postsynaptic GABA responses. However, GHB reduced the amplitude of GABA(A)-IPSPs elicited in pyramidal neurons by paired pulse stimulation and enhanced paired pulse facilitation with respect to control condition, suggesting that GHB reduces GABA release from nerve terminals. Finally, GHB failed to reduce the amplitude of GABA(A)-IPSPs in the presence of BaCl(2), suggesting that the effect of GHB is due to GHB receptor-mediated presynaptic inhibition of Ca(2)+ influx. PMID:12464453

  20. GABA(B) receptor-mediated activation of astrocytes by gamma-hydroxybutyric acid.

    PubMed

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

    2014-10-19

    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 GABA(B) receptors (GABA(B)Rs) where it acts as a weak agonist. Because astrocytes respond to endogenous and exogenously applied GABA by activation of both GABA(A) and GABA(B)Rs, 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 GABA(B)R agonist baclofen. We found that GHB and baclofen elicited dose-dependent (ED50: 1.6 mM and 1.3 µM, respectively) transient increases in intracellular Ca(2+) in VTA and VB astrocytes of young mice and rats, which were accounted for by activation of their GABA(B)Rs and mediated by Ca(2+) 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

  1. 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.

  2. The epidemiology of GHB and ketamine use in an Australian household survey

    Microsoft Academic Search

    Louisa Degenhardt; Matthew Dunn

    2008-01-01

    BackgroundThere have been apparent increases in recent years in the illicit use of ketamine and gamma-hydroxybutyrate (GHB), but to date there has been no examination of the epidemiology of use in the general population. This paper provides the first such Australian data on the patterns and correlates of GHB and ketamine use.

  3. Determination of GHB in urine and serum by LC\\/MS using a simple one-step derivative

    Microsoft Academic Search

    Eckhard Kaufmann; Andreas Alt

    2007-01-01

    A sensitive and specific method for the determination of gamma-hydroxybutyric acid (GHB) in urine and serum is described. Prior to quantification by LC\\/MS in a Pauli-type ion trap, the molecule is converted by a fast and simple one-step procedure into its n-butyl ester derivative. Hexa-deutero GHB has been used as internal standard.

  4. 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 ?M 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

  5. 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

  6. Concurrent use of methamphetamine, MDMA, LSD, ketamine, GHB, and flunitrazepam among American youths

    Microsoft Academic Search

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

    2006-01-01

    BackgroundThe 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 16–23 (N=19,084).

  7. Determination of gamma-hydroxybutyric acid in biological fluids by using capillary electrophoresis with indirect detection.

    PubMed

    Bortolotti, Federica; De Paoli, Giorgia; Gottardo, Rossella; Trattene, Maristella; Tagliaro, Franco

    2004-02-01

    gamma-Hydroxybutyric acid (GHB) is a central nervous system (CNS) depressant and hypnotic which, in recent times, has shown an increasing abuse either as recreational drug (due to its euphoric effects and ability to reduce inhibitions) or as doping agent (enhancer of muscle growth). Analogues of GHB, namely gamma-butyrolactone (GBL) and 1,4-butanediol (1,4-BD), share its biological activity and are rapidly converted in vivo into GHB. At present, GHB and analogues are placed in the Schedules of Controlled Substances. Numerous intoxications in GHB abusers have been reported with depressive effects, seizures, coma and possibly death. The purpose of the present work was the development of a rapid analytical method based on capillary zone electrophoresis for the direct determination of GHB in human urine and serum at potentially toxic concentrations. Analytical conditions were as follows. Capillary: length 40 cm (to detector), 75 microm i.d.; buffer: 5.0 mM Na(2)HPO(4), 15 mM sodium barbital adjusted to pH 12 with 1.0 M NaOH; voltage: 25 kV at 23 degrees C; indirect UV detection at 214 nm; injection by application of 0.5 psi for 5 s. alpha-Hydroxyisobutyric acid was used as internal standard (IS). Sample pretreatment was limited to 1:8 dilution. Under these conditions, the sensitivity was approximately 3.0 microg/ml (signal-to-noise ratio >3). Calibration curves prepared in water, urine and serum were linear over concentration ranges 25-500 microg/ml with R(2)>/=0.998. Analytical precision was fairly good with R.S.D.<0.60% (including intraday and day-to-day tests). Quantitative precision in both intraday and day-to-day experiments was also very satisfactory with R.S.D.GHB determination of biological fluids, which could be important for screening purposes in clinical and forensic toxicology. PMID:14698260

  8. 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

  9. A multi-drug intoxication fatality involving Xyrem (GHB).

    PubMed

    Akins, Brianne E; Miranda, Estuardo; Lacy, J Matthew; Logan, Barry K

    2009-03-01

    Gamma-hydroxybutyrate (GHB) is best known as a recreational depressant drug, whose use has also been implicated in drug facilitated sexual assault cases. It is also available as a therapeutic agent (Xyrem) used for the treatment of daytime sleepiness or cataplexy associated with narcolepsy. This is a report of a case of a 53-year-old woman undergoing treatment with Xyrem for narcolepsy. The decedent was also prescribed tramadol, gabapentin, cetirizine, modafinil, carisoprodol, and Xyrem. Toxicological analysis of the blood revealed GHB 165.6 mg/L, and 90.7 mg/L in the urine. Blood GHB concentrations in the range 156-260 mg/L have been reported to induce moderately sound sleep. The combined use of central nervous system depressant drugs, together with her problematic sleep apnea, and snoring (both contraindications for GHB use) were determined to have caused this subject's death. The manner of death was determined to be accidental. PMID:19187456

  10. The possible influence of micro-organisms and putrefaction in the production of GHB in post-mortem biological fluid

    Microsoft Academic Search

    Simon Elliott; Pauline Lowe; Amanda Symonds

    2004-01-01

    In recent years, the post-mortem production of the drug of abuse gamma-hydroxybutyric acid (GHB) in biological fluids (e.g. blood and urine) has caused various interpretative problems for toxicologists. Previously, other researchers have shown certain microbial species (Pseudomonas spp. and Clostridium aminobutyricum) possess the necessary enzymes to convert GABA to GHB.A preliminary investigation involving putrefied post-mortem blood indicated there was no

  11. A novel method for GHB detection in urine and its application in drug-facilitated sexual assaults

    Microsoft Academic Search

    Albert A Elian

    2000-01-01

    A confirmation procedure for the identification and quantification of gamma-hydroxybutyric acid (GHB) in urine is presented. This method is unique in that it does not involve the conversion of GHB to the gamma-butyrolactone (GBL). The urine samples were extracted using ethyl acetate, evaporated and derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane (TMCS), and analyzed by gas chromatography–mass spectrometry. Quantification was

  12. Central effects of 1,4-butanediol are mediated by GABA(B) receptors via its conversion into gamma-hydroxybutyric acid.

    PubMed

    Carai, Mauro A M; Colombo, Giancarlo; Reali, Roberta; Serra, Salvatore; Mocci, Ignazia; Castelli, M Paola; Cignarella, Giorgio; Gessa, Gian Luigi

    2002-04-26

    The aliphatic alcohol 1,4-butanediol in converted into gamma-hydroxybutyric acid (GHB) via two enzymatic steps: first, it is oxidised by alcohol dehydrogenase in gamma-hydroxybutyraldehyde; second, the latter is transformed, likely by aldehyde dehydrogenase, into GHB. Initially, the present study compared the sedative/hypnotic effect of GHB and 1,4-butanediol, measured as loss of righting reflex. 1,4-Butanediol was more potent than GHB, presumably because of a more rapid penetration of the blood brain barrier. Further alcohol dehydrogenase inhibitors, 4-methylpyrazole and ethanol, totally prevented the sedative/hypnotic effect of 1,4-butanediol; the aldehyde dehydrogenase inhibitor disulfiram partially blocked the sedative/hypnotic effect of 1,4-butanediol. Finally, the sedative/hypnotic effect of 1,4-butanediol was antagonised by the GABA(B) receptor antagonists, SCH 50911 [(2S)(+)-5,5-dimethyl-2-morpholineacetic acid] and CGP 46381 [(3-aminopropyl)(cyclohexylmethyl)phosphinic acid], but not by the putative GHB receptor antagonist NCS-382 (6,7,8,9-tetrahydro-5-hydroxy-5H-benzocyclohept-6-ylideneacetic acid), indicating that it is mediated by GABA(B) but not GHB receptors. Taken together, these results suggest that the sedative/hypnotic effect of 1,4-butanediol is mediated by its conversion in vivo into GHB which, in turn, binds to GABA(B) receptors. Accordingly 1,4-butanediol, unlike GHB, failed to displace [(3)H]GHB and [(3)H]baclofen in brain membranes. PMID:12063087

  13. GHB acid: A rage or reprive.

    PubMed

    Kapoor, Prakhar; Deshmukh, Revati; Kukreja, Ipsita

    2013-10-01

    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

  14. Rapid and direct analysis of gamma-hydroxybutyric acid in urine by capillary electrophoresis-electrospray ionization ion-trap mass spectrometry.

    PubMed

    Gottardo, Rossella; Bortolotti, Federica; Trettene, Maristella; De Paoli, Giorgia; Tagliaro, Franco

    2004-10-01

    The present work was aimed at the development of a capillary electrophoretic analysis of gamma-hydroxybutyric acid (GHB) using electrospray ion trap mass spectrometry to achieve the direct and unequivocal detection of this analyte in human urine. Optimized capillary electrophoretic conditions were: injection, 20 s at 0.5 psi (1 psi = 6894.76 Pa); buffer electrolyte, 12.5 mM ammonium formate adjusted to pH 8.35 with diethylamine; fused silicacapillary: 100 cm x 50 microm i.d.; separation voltage, 25 kV (forward polarity) + 0.5 psi; room temperature. Electrospray and mass spectrometric conditions were: drying gas and nebulizing gas (nitrogen) at flow rate 3 l/min, temperature 250 degrees C, nebulizer pressure: 10 psi; sheath liquid solution: methanol-water (90:10) containing 0.1% ammonia delivered at 3 microl/min; spray voltage 3.5 kV. Mass spetrometric detection was carried out in the selected ion monitoring mode of negative molecular ions at 103 m/z for GHB and 115 m/z for maleic acid (I.S.). Under these conditions the baseline separation of GHB and the I.S. was obtained. The selectivity of the analysis allowed for direct injection of unextracted urine, previously diluted 1:4 with water. Linearity was assessed in the GHB concentration range from 80 to 1280 microg/ml in urine. Analytical sensitivity (as limit of detection) resulted about 5 microg/ml in water and 20 microg/ml in original urine. Analytical precision was fairly acceptable with R.S.D. values lower than 5% for migration times and 18% for quantitation in real samples, in both intra day and day-to-day experiments. On these grounds, the developed method can be adopted for rapid identification of acute intoxications from GHB in humans. PMID:15532575

  15. 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

  16. 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

  17. Screening and confirmation methods for GHB determination in biological fluids.

    PubMed

    Ingels, Ann-Sofie M E; Wille, Sarah M R; Samyn, Nele; Lambert, Willy E; Stove, Christophe P

    2014-06-01

    The purpose of this review is to provide a comprehensive overview of reported methods for screening and confirmation of the low-molecular-weight compound and drug of abuse gamma-hydroxybutyric acid (GHB) in biological fluids. The polarity of the compound, its endogenous presence, its rapid metabolism after ingestion, and its instability during storage (de novo formation and interconversion between GHB and its lactone form gamma-butyrolactone) are challenges for the analyst and for interpretation of a positive result. First, possible screening procedures for GHB are discussed, including colorimetric, enzymatic, and chromatography-based procedures. Confirmation methods for clinical and forensic cases mostly involve gas chromatography (coupled to mass spectrometry), although liquid chromatography and capillary zone electrophoresis have also been used. Before injection, sample-preparation techniques include (a combination of) liquid-liquid, solid-phase, or headspace extraction, and chemical modification of the polar compound. Also simple "dilute-and-shoot" may be sufficient for urine or serum. Advantages, limitations, and trends are discussed. PMID:24500753

  18. 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,…

  19. Cloning and functional characterization of a gamma-hydroxybutyrate receptor identified in the human brain

    Microsoft Academic Search

    Christian Andriamampandry; Omar Taleb; Veronique Kemmel; Jean-Paul Humbert; Dominique Aunis; Michel Maitre

    2007-01-01

    Two parent clones of a -hydroxybu- tyrate (GHB) receptor, C12K32 and GHBh1, were isolated from a human frontal cortex cDNA library. The two clones differ by a deleted cytosine in C12K32. CHO cells transfected with either C12K32 or GHBh1 responded positively to submicromolar GHB stimula- tion. However, unlike C12K32, GHBh1 desensitizes rapidly on application of low concentrations of GHB. GHB

  20. 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

  1. Baclofen and ?-hydroxybutyrate (GHB), a dangerous combination.

    PubMed

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

    2015-01-01

    Baclofen is a ?-aminobutyric acid (GABA)-? receptor agonist with a muscle relaxant effect. It increases GABA activity and reduces the production of glutamate and dopamine. The GABA precursor ?-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

  2. A long hangover from party drugs: residual proteomic changes in the hippocampus of rats 8 weeks after ?-hydroxybutyrate (GHB), 3,4-methylenedioxymethamphetamine (MDMA) or their combination.

    PubMed

    van Nieuwenhuijzen, Petra S; Kashem, Mohammed A; Matsumoto, Izuru; Hunt, Glenn E; McGregor, Iain S

    2010-07-01

    3,4-Methylenedioxymethamphetamine (MDMA) and gamma-hydroxybutyrate (GHB) are popular party drugs that are used for their euphoric and prosocial effects, and sometimes in combination. Both drugs increase markers of oxidative stress in the hippocampus and can cause lasting impairments in hippocampal-dependent forms of memory. To gain further information on the biochemical mechanisms underlying these effects, the current study examined residual changes in hippocampal protein expression measured 8 weeks after chronic administration of GHB (500mg/kg), MDMA (5mg/kg) or their combination (GHB/MDMA). The drugs were administered once a day for 10 days in an environment with an elevated ambient temperature of 28 degrees C. Results showed significant changes in protein expression, relative to controls, in all three groups: MDMA and GHB given alone caused residual changes in 8 and 5 proteins respectively, while the GHB/MDMA combination significantly changed 6 proteins. The altered proteins had roles in neuroplasticity, neuroprotection, intracellular signalling and cytoskeletal function. The largest change (-4.3-fold) was seen in the MDMA group with the protein C-crk: a protein implicated in learning-related neuroplasticity. The second largest change (3.0-fold) was seen in the GHB group in Glutathione-S-transferase (GST), a protein that protects against oxidative stress. Two cytoskeletal proteins (Tubulin Folding Cofactor B and Tropomyosin-alpha-3 chain) and one plasticity related protein (Neuronal Pentraxin-1 NP1) were similarly changed in both the MDMA and the GHB groups, while two intracellular signalling proteins (alpha-soluble NSF-attachment protein and subunits of the V-type proton ATPase) were changed in both the MDMA/GHB and the MDMA groups. These results provide some insight into the molecular pathways possibly underlying the lasting cognitive deficits arising from GHB and/or MDMA use. PMID:20227452

  3. 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 ? = .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

  4. Club Drugs (GHB, Ketamine, and Rohypnol)

    MedlinePLUS

    ... Club Drugs (GHB, Ketamine, and Rohypnol) DrugFacts: Club Drugs (GHB, Ketamine, and Rohypnol) Email Facebook Twitter Revised ... mostly used in veterinary practice. How Are Club Drugs Abused? GHB and Rohypnol are available in odorless, ...

  5. 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

  6. Management of Gamma-Butyrolactone Dependence with Assisted Self-Administration of GBL.

    PubMed

    Meyer, Rafael; Jenewein, Josef; Boettger, Soenke

    2014-01-01

    Gamma-hydroxybutyric acid (GHB) and its liquid precursor gamma-butyrolactone (GBL) have become increasingly popular beyond the clubbing culture resulting in daily consumption and dependence in the broader population. This case report illustrates the challenges of managing GHB-withdrawal and a possibly superior future approach of its management by titration and tapering of the addictive agent. PMID:25054071

  7. 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

  8. 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. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24947196

  9. Behavioral analyses of GHB: Receptor mechanisms

    Microsoft Academic Search

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

    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

  10. 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, ?-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 (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

  11. 76 FR 17968 - Manufacturer of Controlled Substances; Notice of Registration

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-31

    ...registered as a bulk manufacturer of Gamma Hydroxybutyric Acid (GHB) (2010), a basic class of controlled substance listed in...The company plans to manufacture Gamma Hydroxybutyric Acid (GHB) [[Page 17969

  12. 75 FR 53719 - Manufacturer of Controlled Substances; Notice of Application

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-01

    ...registered as a bulk manufacturer of Gamma Hydroxybutyric Acid (GHB) (2010), a basic class of controlled substance listed in...The company plans to manufacture Gamma Hydroxybutyric Acid (GHB) (2010) in bulk active pharmaceutical ingredient (API)...

  13. 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.

  14. Effect of storage temperature on endogenous GHB levels in urine

    Microsoft Academic Search

    Marc A LeBeau; Mark L Miller; Barry Levine

    2001-01-01

    Because ?-hydroxybutyrate (GHB) is an endogenous substance present in the body and is rapidly eliminated after ingestion, toxicologists investigating drug-facilitated sexual assault cases are often asked to differentiate between endogenous and exogenous levels of GHB in urine samples.This study was designed to determine the effects of storage temperature on endogenous GHB levels in urine. Specifically, it was designed to ascertain

  15. What You Need to Know about Drugs: GHB

    MedlinePLUS

    ... Does to You: GHB causes both a euphoric high (intense rush of happy feelings) and hallucinations. GHB has caused many young people to need emergency medical care. Because the liquid is odorless and colorless, GHB diluted in drinks is virtually undetectable and sometimes is ...

  16. 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 (?-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 ?-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

  17. Relative Abuse Liability of GHB in Humans: A Comparison of Psychomotor, Subjective, and Cognitive Effects of Supratherapeutic Doses of Triazolam, Pentobarbital, and GHB

    Microsoft Academic Search

    Lawrence P Carter; Brian D Richards; Miriam Z Mintzer; Roland R Griffiths

    2006-01-01

    Although preclinical studies suggest that GHB has low likelihood for abuse, case reports indicate that GHB is abused. This study evaluated the relative abuse liability of GHB in 14 volunteers with histories of drug abuse. Psychomotor, subjective, and cognitive effects of a broad range of GHB doses (2–18 g\\/70 kg), up to a dose that produced severe behavioral impairment in

  18. Selective breeding of two rat lines differing in sensitivity to GHB and baclofen

    Microsoft Academic Search

    Giancarlo Colombo; Carla Lobina; Roberta Agabio; Giuliana Brunetti; Giacomo Diaz; Martino Littera; Samuele Melis; Marialaura Pani; Roberta Reali; Salvatore Serra; Giovanni Vacca; Mauro A. M Carai; Gian Luigi Gessa

    2001-01-01

    Two Wistar-derived rat lines, one sensitive (GHB-S) and the other resistant (GHB-R) to the anesthetic effect of ?-hydroxybutyric acid (GHB), have been selectively bred. GHB-S and GHB-R rats were also sensitive and resistant, respectively, to the anesthetic effect of baclofen, the prototype GABAB receptor agonist, suggesting that they may be useful to elucidate not only the role of endogenous GHB

  19. Forensic cases involving the use of GHB in The Netherlands

    Microsoft Academic Search

    Ingrid J. Bosman; Klaas J. Lusthof

    2003-01-01

    In this study, forensic cases involving the use of Gamma Hydroxy Butyric acid (GHB) from the second half of 1999 through the second half of 2001 in The Netherlands (blood >5mg\\/l and urine >10mg\\/l) are described. GHB was analysed by GC–MS after lactone formation and using GHB-d6 as internal standard. The results are divided into three groups: cases of chemical

  20. Determination of gamma-hydroxybutyric acid in biofluids using a one-step procedure with "in-vial" derivatization and headspace-trap gas chromatography-mass spectrometry.

    PubMed

    Ingels, Ann-Sofie M E; Neels, Hugo; Lambert, Willy E; Stove, Christophe P

    2013-06-28

    A headspace-trap gas chromatography-mass spectrometry (HS-trap GC-MS) method was developed to determine GHB, a low molecular weight compound and drug of abuse, in various biological fluids. Combining this relatively novel and fully automated headspace technique with "in-vial" methylation of GHB allowed for a straightforward approach. One single method could be used for all biofluids (urine, plasma, serum, whole blood or lyzed blood), requiring only 100?l of sample. Moreover, our approach involves mere addition of all reagents and sample into one vial. Following optimization of headspace conditions and trap settings, validation was performed. Although sample preparation only consists of the addition of salt and derivatization reagents directly to a 100?l-sample in a HS-vial, adequate method sensitivity and selectivity was obtained. Calibration curves ranged from 5 to 150?g/ml GHB for urine, from 2 to 150?g/ml for plasma, and from 3.5 to 200?g/ml for whole blood. Acceptable precision and accuracy (<13% bias and imprecision) were seen for all quality controls (QC's) (LLOQ-level, low, medium, high), including for the supplementary serum- and lyzed blood-based QC's, using calibration curves prepared in plasma or whole blood, respectively. Incurred sample reanalysis demonstrated assay reproducibility, while cross-validation with another GC-MS method demonstrated that our method is a valuable alternative for GHB determination in toxicological samples, with the advantage of requiring only 100?l and minimal hands-on time, as sample preparation is easy and injection automated. PMID:23664352

  1. Blockade of the discriminative stimulus effects of ?-hydroxybutyric acid (GHB) by the GHB receptor antagonist NCS382

    Microsoft Academic Search

    Giancarlo Colombo; Roberta Agabio; Jacques Bourguignon; Fabio Fadda; Carla Lobina; Michel Maitre; Roberta Reali; Martine Schmitt; Gian Luigi Gessa

    1995-01-01

    The present study was designed to assess the ability of the newly synthetized, selective ?-hydroxybutyric acid (GHB) receptor antagonist, NCS-382, in blocking the discriminative stimulus effects of GHB in a T-maze, food-reinforced drug discrimination procedure. Two groups of rats were trained to run the left arm of the maze 30 min after the i.g. administration of either 300 or 700

  2. 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

  3. EEG-Veränderungen unter Sedierung mit ?-Hydroxybuttersäure (GHB)

    Microsoft Academic Search

    E. Entholzner; L. Mielke; R. Pichlmeier; F. Weber; H. Schneck

    1995-01-01

    Zusammenfassung  \\u000a \\u000a \\u000a Gamma-Hydroxybuttersäure (GHB) als zentraler Neurotransmitter wird zur Sedierung in der Intensivmedizin eingesetzt. Trotz\\u000a insgesamt sehr günstigen pharmakologischen Profils wurde seine Eignung in Frage gestellt, da es beim Tier in sehr hoher Dosierung\\u000a Krampfpotentiale auslösen kann und in dieser Absicht sogar als Modellsubstanz für die Absenzen-typische Attacke dient. Nach\\u000a eigenen positiven Erfahrungen mit GHB im klinischen Einsatz wurde bei 31

  4. Risk assessment of GBL as a substitute for the illicit drug GHB in the Netherlands. A comparison of the risks of GBL versus GHB.

    PubMed

    van Amsterdam, Jan; Brunt, Tibor; Pennings, Ed; van den Brink, Wim

    2014-11-01

    In the Netherlands, ?-hydroxybutyric acid (GHB) was recently banned, but ?-butyrolactone (GBL) was not. As such, GBL remained a legal alternative to GHB. This review compares the risks of GBL and GHB. Pure GBL is per unit of volume about threefold stronger and therefore threefold more potent than currently used GHB-preparations in the Netherlands. Like GHB, GBL use hardly leads to organ toxicity, although, as with GHB, frequent GBL use may lead to repeated comas that may result in residual impairments in cognitive function and memory. Little is known about the prevalence of GBL use in Europe, but the recent increase in improper trading in GBL confirms that users of GHB gradually switch to the use of GBL. This shift may result in an increase in the number GBL dependent users, because the dependence potential of GBL is as great as that of GHB. Severe withdrawal symptoms and a high relapse rate are seen following cessation of heavy GBL use. GBL-dependent users seem to be severe (dependent, problematic) GHB users who started using GBL, the legal GHB substitute. Subjects who are solely dependent to GBL are rarely reported. About 5-10% of the treatment seeking GHB dependent subjects also use GBL and this subpopulation forms a vulnerable group with multiple problems. Fatal accidents with GBL are rarely reported, but non-fatal GHB (or GBL) overdoses frequently occur for which supportive treatment is needed. It is recommended to monitor the recreational use of GBL, the rate of GBL dependence treatment, and the improper trading of GBL. PMID:25204614

  5. 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

    ?-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

  6. Genetics Home Reference: Succinic semialdehyde dehydrogenase deficiency

    MedlinePLUS

    ... GABA and a related molecule called gamma-hydroxybutyrate (GHB) in the body, particularly the brain and spinal ... is unclear how an increase in GABA and GHB causes developmental delay, seizures, and other signs and ...

  7. Evaluation of the discriminative stimulus and reinforcing effects of gammahydroxybutyrate (GHB)

    Microsoft Academic Search

    Patrick M. Beardsley; Robert L. Balster; Louis S. Harris

    1996-01-01

    Gammahydroxybutyrate (GHB) satisfies many of the criteria for consideration as a neurotransmitter including having specific\\u000a receptor sites, endogenous synthesis, and heterogeneous CNS distribution. GHB has been reported to be illicitly used, to induce\\u000a physical dependence, and to relieve effects from alcohol and heroin withdrawal. GHB has also been shown to have antidopaminergic\\u000a activity to displace3H[MK-801] binding in brain membranes, and

  8. 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 -20°C. 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

  9. Regulation of ?-aminobutyric acid (GABA) release in cerebral cortex in the ?-hydroxybutyric acid (GHB) model of absence seizures in rat

    Microsoft Academic Search

    R. Q Hu; P. K Banerjee; O. C Snead III

    2000-01-01

    ?-Hydroxybutyric acid (GHB) has the ability to induce absence seizures. The precise way in which GHB causes seizures remains unclear, but GABAB- and\\/or GHB-mediated presynaptic mechanisms within thalamocortical circuitry may play a role. In the present study, we determined the basal and K+-evoked release of GABA and glutamate in the superficial laminae of frontal cortex during GHB-induced absence seizures. Our

  10. Urinary endogenous concentrations of GHB and its isomers in healthy humans and diabetics

    Microsoft Academic Search

    Noriaki Shima; Akihiro Miki; Tooru Kamata; Munehiro Katagi; Hitoshi Tsuchihashi

    2005-01-01

    Urinary endogenous concentrations of ?-hydroxybutyric acid (GHB), ?-hydroxybutyric acid (AHB) and ?-hydroxybutyric acid (BHB) have been investigated for both healthy humans and diabetics by using a newly optimized GC–MS procedure. The endogenous concentrations in healthy volunteers’ urine ranged 0.16–2.14?g\\/ml for GHB, 0.10–2.68?g\\/ml for AHB and 8.51–34.7?g\\/ml for BHB. In diabetics, the concentrations ranged 0.17–3.03?g\\/ml for GHB, 0.14–124?g\\/ml for AHB and

  11. Relation of the [ 3H]?-hydroxybutyric acid (ghb) binding site to the ?-aminobutyric acid b (gaba b) receptor in rat brain

    Microsoft Academic Search

    O. Carter Snead

    1996-01-01

    Hydroxybutyric acid (GHB) is a naturally occurring compound that has the ability to induce generalized absence seizures when given to animals. GHB has been hypothesized to induce this effect via the postsynaptic ?-aminobutyric acidB (GABAB) receptor. We sought to test this hypothesis by examining the affinity of GABAB agonists and antagonists for the [3H]GHB binding site, the affinity of GHB

  12. Gammahydroxybutyrate increases tryptophan availability and potentiates serotonin turnover in rat brain

    Microsoft Academic Search

    Serge Gobaille; Carmen Schleef; Viviane Hechler; Sandrine Viry; Dominique Aunis; Michel Maitre

    2002-01-01

    Gamma-hydroxybutyrate (GHB) is both a therapeutic agent and a recreative drug. It has sedative, anxiolytic and euphoric effects. These effects are believed to be due to GHB-induced potentiation of cerebral GABAergic and dopaminergic activities, but the serotonergic system might also be involved. In this study, we examine the effects of pharmacological doses of GHB on the serotonergic activity in rat

  13. Club Drugs

    MedlinePLUS

    Club drugs are group of psychoactive drugs. They act on the central nervous system and can cause changes ... Molly, Hug Beans, and Love Drug Gamma-hydroxybutyrate (GHB), also known as G, Liquid Ecstasy, and Soap ...

  14. 76 FR 68167 - Spin Master, Inc. and Spin Master, Ltd., Provisional Acceptance of a Settlement Agreement and Order

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-03

    ...contained 1,4-butylene glycol (``TMG''). TMG is a chemical that, upon ingestion, metabolizes to gamma hydroxybutyrate (GHB), a Schedule I controlled substance. On October 19, 2007, Spin Master received information that TMG is harmful if...

  15. Near-fatal persistent anion- and osmolal-gap acidosis due to massive gamma-butyrolactone/ethanol intoxication.

    PubMed

    Heytens, Luc; Neels, Hugo; Van Regenmortel, Niels; van den Brink, Wim; Henckes, Manu; Schouwers, Sofie; Dockx, Greet; Crunelle, Cleo L

    2015-03-01

    We report a case of an ethanol and massive gamma-butyrolactone (GBL) intoxication, the precursor of the recreational drug gamma-hydroxybutyric acid (GHB), resulting in life-threatening metabolic acidosis (pH 6.5) with a highly increased anion- and osmolal gap. Rapid analysis using gas chromatography revealed a GHB plasma concentration of 4400?mg/L, far above the upper limit concentration of 1000?mg/L found in adult fatalities attributed to GBL. Full recovery was established following supportive treatment including haemodialysis. This is the first report of a combined ethanol/GBL intoxication as a cause of high serum anion- and osmolal-gap metabolic acidosis. PMID:25205856

  16. 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.…

  17. Positive allosteric modulation of the GHB high-affinity binding site by the GABAA receptor modulator monastrol and the flavonoid catechin.

    PubMed

    Eghorn, Laura F; Hoestgaard-Jensen, Kirsten; Kongstad, Kenneth T; Bay, Tina; Higgins, David; Frølund, Bente; Wellendorph, Petrine

    2014-10-01

    ?-Hydroxybutyric acid (GHB) is a metabolite of ?-aminobutyric acid (GABA) and a proposed neurotransmitter in the mammalian brain. We recently identified ?4?? GABAA receptors as possible high-affinity GHB targets. GABAA receptors are highly sensitive to allosteric modulation. Thus to investigate whether GHB high-affinity binding sites are also sensitive to allosteric modulation, we screened both known GABAA receptor ligands and a library of natural compounds in the rat cortical membrane GHB specific high-affinity [3H]NCS-382 binding assay. Two hits were identified: Monastrol, a positive allosteric modulator of GABA function at ?-containing GABAA receptors, and the naturally occurring flavonoid catechin. These compounds increased [3H]NCS-382 binding to 185-272% in high micromolar concentrations. Monastrol and (+)-catechin significantly reduced [3H]NCS-382 dissociation rates and induced conformational changes in the binding site, demonstrating a positive allosteric modulation of radioligand binding. Surprisingly, binding of [3H]GHB and the GHB high-affinity site-specific radioligands [125I]BnOPh-GHB and [3H]HOCPCA was either decreased or only weakly increased, indicating that the observed modulation was critically probe-dependent. Both monastrol and (+)-catechin were agonists at recombinant ?4?3? receptors expressed in Xenopus laevis oocytes. When monastrol and GHB were co-applied no changes were seen compared to the individual responses. In summary, we have identified the compounds monastrol and catechin as the first allosteric modulators of GHB high-affinity binding sites. Despite their relatively weak affinity, these compounds may aid in further characterization of the GHB high-affinity sites that are likely to represent certain GABAA receptors. PMID:24973695

  18. New synthesis and tritium labeling of a selective ligand for studying high-affinity ?-hydroxybutyrate (GHB) binding sites.

    PubMed

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

    2013-10-24

    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 [(3)H]-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 [(3)H]-1 binding shows high specificity to the high-affinity GHB binding sites. PMID:24053696

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

    PubMed Central

    Vogensen, Stine B.; Marek, Aleš; Bay, Tina; Wellendorph, Petrine; Kehler, Jan; Bundgaard, Christoffer; Frølund, 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

  20. 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 ?-hydroxybutyric acid (GHB) and ?-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

  1. Survey and assessment of the actual state of routine measurement of glycohaemoglobin\\/GHb by commercial methods: warning to the users and the providers

    Microsoft Academic Search

    Tadao Hoshine; Mikiko Okahashi; Hiroko Arai

    1997-01-01

    As the clinical availability of glycohaemoglobin\\/GHb measurement increases, so does the need for comparable and accurate values among different laboratories and different methods. At least there should be comparability, i.e., commutability or feasibility of providing comparable results from different assays in different laboratories. A clinical joint study on insulin therapy, a survey of the actual inter-laboratory differences in GHb measurement

  2. Quantitative autoradiographic analysis of the new radioligand [ 3H](2 E)-(5-hydroxy-5,7,8,9-tetrahydro-6H-benzo[ a][7]annulen-6-ylidene) ethanoic acid ([ 3H]NCS382) at ?-hydroxybutyric acid (GHB) binding sites in rat brain

    Microsoft Academic Search

    Georgianna G. Gould; Ashok K. Mehta; Alan Frazer; Maharaj K. Ticku

    2003-01-01

    (2E)-(5-Hydroxy-5,7,8,9-tetrahydro-6H-benzo[a][7]annulen-6-ylidene) ethanoic acid (NCS-382) is an antagonist for ?-hydroxybutyric acid (GHB) at GHB receptor sites. Advantages of using [3H]NCS-382 over [3H]GHB in radioligand binding studies are that unlike GHB, NCS-382 does not appear to bind to, activate, or interfere with the functioning of GABAB or GABAA receptors, either directly or indirectly. Herein we establish a protocol for use of [3H]NCS-382

  3. 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.

  4. 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.

  5. Avalanche precursors R. Delannay,

    E-print Network

    Gruner, Daniel S.

    Avalanche precursors R. Delannay, Institut de Physique de Rennes, Université de Rennes 1, CNRS UMR at the top of the tray after some avalanches. · 4 or 5 large avalanches then observed during the slow of small "avalanches" which are recorded by a camera.2mm diameter beads #12;N. Nérone et al. Physica A 283

  6. Role of g -Aminobutyrate and g -Hydroxybutyrate in Plant Communication

    Microsoft Academic Search

    Barry J. Shelp; Wendy L. Allan; Denis Faure

    The neurotransmitters gamma-aminobutyrate (GABA) and gamma-hydroxybutyrate (GHB) are found in virtually all prokaryotic and\\u000a eukaryotic organisms. The physiological roles of these metabolites in plants are not yet clear, but both readily accumulate\\u000a in response to stress through a combination of biochemical and transcriptional processes. GABA accumulation has been associated\\u000a with the appearance of extracellular GABA, and evidence is available for

  7. [Fatigue in substance abuse disorders].

    PubMed

    Aichmüller, 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

  8. A validated SPME-GC–MS method for simultaneous quantification of club drugs in human urine

    Microsoft Academic Search

    Stacy D. Brown; Daniel J. Rhodes; Boyd J. Pritchard

    2007-01-01

    A solid-phase microextraction-gas chromatographic–mass spectrometric (SPME-GC–MS) method has been developed and validated for measuring four club drugs in human urine. These drugs include gamma-hydroxybutyrate (GHB), ketamine (KET), methamphetamine (MAMP), and methylenedioxymethamphetamine (MDMA). These drugs are referred to as ‘club drugs’ because of their prevalence at parties and raves. Deuterium labeled internal standards for each of the four drugs was included

  9. Polymeric precursors for yttria

    SciTech Connect

    Apblett, A.W.; Cannon, S.M.; Georgieva, G.D.; Long, J.C.; Raygoza-Maceda, I.; Reinhardt, L.E. [Tulane Univ., New Orleans, LA (United States). Dept. of Chemistry

    1994-12-31

    Polymers that can be easily processed into fibers, films, or bodies are excellent precursors for ceramics with useful morphologies. The ideal preceramic polymer not only has proper physical properties (e.g. solubility or fusibility) for processibility but also decomposes at low temperature with high ceramic yield. One possibility for such precursors for yttria are yttrium oxycarboxylates. The preparation of such polymers from YOCl has been investigated and several compounds with useful physical properties have been discovered. These include a methanol-soluble yttrium oxycarboxylate, (CH{sub 3}OCH{sub 2}CH{sub 2}OCH{sub 2}CO{sub 2}YO){sub n}, a liquid yttrium tricarboxylate, (CH{sub 3}OCH{sub 2}CH{sub 2}OCH{sub 2}CO{sub 2}){sub 3}Y, and a method for preparing very concentrated yttrium mixed acetate and formate sols.

  10. Osteoclast Precursor Cells

    Microsoft Academic Search

    Joseph A. Lorenzo

    \\u000a The hematopoietic origin of the osteoclast is now clear. Walker (Walker 1975b, Walker 1975a, Walker 1975c) first demonstrated\\u000a that the precursor cells of osteoclasts were hematopoietic. These studies showed that the transplant of spleen cells from\\u000a osteopetrotic mice, which have dysfunctional osteoclasts, into irradiated normal animals caused the normal animals to become\\u000a osteopetrotic within four weeks. Conversely, it was shown

  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. 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.

  13. 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.

  14. Precursor Flares in OJ 287

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    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 zc = 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.

  15. 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, ...

  16. Brillouin precursors in Debye media

    E-print Network

    Macke, Bruno

    2015-01-01

    We theoretically study the formation of Brillouin precursors in Debye media. We point out that the precursors are only visible at propagation distances such that the impulse response of the medium is essentially determined by the frequency-dependence of its absorption and is practically Gaussian. By simple convolution, we then obtain explicit analytical expressions of the transmitted waves generated by reference incident waves, distinguishing precursor and main signal by physical arguments. These expressions are in good agreement with the signals obtained in numerical or real experiments performed on water and explain some features of these signals that remained mysterious or unnoticed. In addition, we show quite generally that the shape of the Brillouin precursor appearing alone at large enough propagation distance and the law giving its amplitude as a function of this distance do not depend on the precise form of the incident wave but only on its integral properties. The incidence of a static conductivity o...

  17. Fractional precursors in random media

    NASA Astrophysics Data System (ADS)

    Garnier, Josselin; Sølna, Knut

    2010-01-01

    When a broadband pulse penetrates into a dissipative and dispersive medium, phase dispersion and frequency-dependent attenuation alter the pulse in a way that results in the appearance of a precursor field with an algebraic decay. We derive here the existence of precursors in non-dispersive, non-dissipative, but randomly heterogeneous and multiscale media. The shape of the precursor and its fractional power law decay with propagation distance depend on the random medium class. Three principal scattering precursor classes can be identified: (i) in exponentially decorrelating random media, and more generally in mixing random media, the precursor has a Gaussian shape and a peak amplitude that decays as the square root of the inverse of the propagation distance. (ii) In short-range correlation media, with rough multiscale medium fluctuations, the precursor has a skewed shape with a tail that exhibits an anomalous power law decay in time and a peak amplitude that exhibits an anomalous power law decay with propagation distance, both of which depend on the Hurst exponent that characterizes the roughness of the medium. (iii) In long-range correlation media with long-range memory, the situation mimics that of class (ii), but with modified power laws.

  18. Brillouin precursors in Debye media

    NASA Astrophysics Data System (ADS)

    Macke, Bruno; Ségard, Bernard

    2015-05-01

    We theoretically study the formation of Brillouin precursors in Debye media. We point out that the precursors are visible only at propagation distances such that the impulse response of the medium is essentially determined by the frequency dependence of its absorption and is practically Gaussian. By simple convolution, we then obtain explicit analytical expressions of the transmitted waves generated by reference incident waves, distinguishing precursor and main signal by a simple examination of the long-time behavior of the overall signal. These expressions are in good agreement with the signals obtained in numerical or real experiments performed on water in the radio-frequency domain and explain in particular some observed shapes of the precursor. Results are obtained for other remarkable incident waves. In addition, we show quite generally that the shape of the Brillouin precursor appearing alone at sufficiently large propagation distance and the law giving its amplitude as a function of this distance do not depend on the precise form of the incident wave but only on its integral properties. The incidence of a static conductivity of the medium is also examined and explicit analytical results are again given in the limit of weak and strong conductivities.

  19. Optical precursors in transparent media

    SciTech Connect

    Macke, Bruno; Segard, Bernard [Laboratoire de Physique des Lasers, Atomes et Molecules (PhLAM), Centre d'Etudes et de Recherches Lasers et Applications, CNRS et Universite Lille 1, 59655 Villeneuve d'Ascq (France)

    2009-07-15

    We theoretically study the linear propagation of a stepwise pulse through a dilute dispersive medium when the frequency of the optical carrier coincides with the center of a natural or electromagnetically induced transparency window of the medium (slow-light systems). We obtain fully analytical expressions of the entirety of the step response and show that, for parameters representative of real experiments, Sommerfeld-Brillouin precursors, main field and second precursors ('postcursors') can be distinctly observed, all with amplitudes comparable to that of the incident step. This behavior strongly contrasts with that of the systems generally considered up to now.

  20. Current topics on precursors to pancreatic cancer

    Microsoft Academic Search

    Takaori K; Hruban RH; Maitra A; Tanigawa N

    2006-01-01

    Prognosis of invasive pancreatic ductal adenocarcinoma is bleak and the vast majority of patients with pancreatic cancer die of their disease. The detection and treatment of the non- invasive precursor lesions of pancreatic cancer offer the oppor- tunity to cure this devastating disease and therefore great efforts are being made to identify the precursors to pancreatic cancer. Several distinct precursor

  1. Vapor pressure of germanium precursors

    Microsoft Academic Search

    J. Pangrác; M. Fulem; E. Hulicius; K. Melichar; T. Šime?ek; K. Ruzicka; P. Morávek; V. R?ži?ka; S. A. Rushworth

    2008-01-01

    The vapor pressure of two germanium precursors tetrakis(methoxy)germanium (Ge(OCH3)4, CASRN 992-91-6) and tetrakis(ethoxy)germanium (Ge(OC2H5)4, CASRN 14165-55-0) was determined using a static method in the temperature range 259–303K. The experimental vapor pressure data were fit with the Antoine equation. The mass spectra before and after degassing by vacuum distillation at low temperature are also reported and discussed.

  2. 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.

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

    PubMed

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

    2013-12-31

    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 (1)H-NMR, (1)H-COSY, and (1)H-DOSY NMR methods, a proton exchange from C-8 of caffeine to eosin Y is proposed. PMID:25018772

  4. Accident precursor program at Duke Power Company

    SciTech Connect

    Busby, B.E.; Canady, K.S.; Abraham, P.M. (Duke Power Co., Charlotte, NC (United States))

    1992-01-01

    A program for identifying and evaluating precursor events at Duke nuclear plants utilizing probabilistic risk assessment (PRA) methodology was initiated in 1990. This Duke precursor program is similar to the U.S. Nuclear Regulatory Commission (NRC)-established accident sequence precursor (ASP) program but has the added flexibility to utilize the plant-specific PRA models, data, and unique system features. The overall objective of the Duke precursor program is to obtain a quantitative understanding of the actual safety performance of the plant by considering the occurrence of those events that are challenging or reducing the design safety margins.

  5. Premarital precursors of marital infidelity.

    PubMed

    Allen, Elizabeth S; Rhoades, Galena Kline; Stanley, Scott M; Markman, Howard J; Williams, Tamara; Melton, Jessica; Clements, Mari L

    2008-06-01

    Premarital precursors of infidelity were evaluated in a sample of 72 couples (N = 144) who were taking part in a longitudinal study of marriage. Premarital self-report and observational data were compared for couples who experienced infidelity and those who did not experience infidelity in the first years of marriage. Couples in which the male engaged in marital infidelity were characterized, premaritally, by significantly lower male sexual satisfaction, lower male positive communication, and higher female invalidation, whereas couples in which the female went on to engage in infidelity were characterized, premaritally, by significantly lower levels of female positive communication, higher levels of male and female negative communication, and higher levels of male and female invalidation. Implications of the findings for future research on the prediction and prevention of infidelity are discussed. PMID:18605124

  6. Precursors for Carbon Nitride Synthesis

    SciTech Connect

    Prashantha, M.; Gopal, E. S. R.; Ramesh, K. [Department of Physics, Indian Institute of Science, Bangalore 560012 (India)

    2011-07-15

    Nano structured carbon nitride films were prepared by pyrolysis assisted chemical vapour deposition. Pyrrole (C{sub 4}H{sub 5}N), Pyrrolidine (C{sub 4}H{sub 9}N), Azabenzimidazole (C{sub 6}H{sub 5}N{sub 3}) and Triazine (C{sub 6}H{sub 15}N{sub 3}) were used as precursors. The vibrational modes observed for C-N and C = N from FTIR spectra confirms the bonding of nitrogen with carbon. XPS core level spectra of C 1s and N 1s also show the formation of bonding between carbon and nitrogen atoms. The nitrogen content in the prepared samples was found to be around 25 atomic %.

  7. THE DELAYED NEUTRON PRECURSORS IN FISSION

    Microsoft Academic Search

    1959-01-01

    A survey of the experimental data on delayed neutron half lives and ; yields gives indication for the existence of a greater number of delayed neutron ; precursors than the six commonly accepted. This finds further support in the ; fact that the ratio of delayed neutron yield to cumulative fission yield of a ; delayed neutron precursor depends on

  8. Laboratory Study of Shock Wave Precursors

    Microsoft Academic Search

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

    1996-01-01

    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

  9. Response of inorganic PM to precursor concentrations

    Microsoft Academic Search

    Asif S. Ansari; Spyros N. Pandis

    1998-01-01

    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 showing regions of PM response to precursor concentrations are generated, thus allowing the qualification of assumptions concerning the response of PM

  10. PKP precursors: Implications for global scatterers

    NASA Astrophysics Data System (ADS)

    Waszek, Lauren; Thomas, Christine; Deuss, Arwen

    2015-05-01

    Precursors to the core phase PKP are generated by scattering of seismic energy from heterogeneities in the mantle. Here we examine a large global data set of PKP precursors in individual seismograms and array data, to better understand scattering locations. The precursor amplitudes from individual seismograms are analyzed with respect to the inner core phase PKIKP and mantle phase PP. We find and correct for a hemispherical asymmetry in the precursor/PKIKP amplitudes, resulting from inner core structure. Using ray tracing, we locate scatterers in our array data and use these to infer scattering locations in the individual data. The scattering strength displays regional variation; however, we find no relationship with long-scale core-mantle boundary velocity structure. Scattering is observed in all regions of data coverage, as are paths with no precursors. This indicates that scattering occurs from various small-scale heterogeneities, including but not limited to ultralow velocity zones or partial melt, and slabs.

  11. 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.

  12. Radio HF precursors of Earthquakes

    NASA Astrophysics Data System (ADS)

    Ruzhin, Yu.; Nomicos, C.; Vallianatos, F.; Shpakovsky, V.

    The high frequency (HF) earthquake electromagnetic precursors (40-55MHz band) were recorded by the four electromagnetic stations a few days (hours) prior the event associated with earthquakes with magnitude more than 5.0 at Crete Island. These experiments were performed continuously during 1998-2002 and specific peculiarities are found. This is underhorizon epicenter position for main part of events under question. Another unusual result is that such HF preseismic radio noise-like signals are responsible for seaquakes too. We made conclusion about developing of some thunderstorm-like charged clouds activity in atmosphere before the seismic event. As result of our analysis and interpretation of the available data of continuous observations on a network of Crete island we should state here, that in an atmosphere above the sea on the eve of earthquake at heights of 0.1-10 km the spatially distributed spots of sporadic charged clouds are occurred and the conditions for the electrical discharges in an atmosphere are created which can serve a source of HF radio-emission registered by Crete network. The atmosphere theory relations are used to model a corresponding to an anomalous event emissions generation observed on the Crete. The supposed mechanism of preseismic electricity generation is the model of convection carrier started in an atmosphere. It is governed by the horizontal gradient of air temperature. The occurrence of electrical charges in a surface of the sea and transportation them further on heights up to 10 km in our model occurs due to sporadic energy injections that allocated within bottom of the sea as gases and heat. The dimensions of width and height govern the size of atmosphere convection cells in the earthquake preparation area. These dimensions of the sporadic spots are close to 3 km each as it is derived from shadow geometry and spectral fluctuations of HF signal. Based on experience of Crete HF precursors observation the method for satellite mapping of HF emission (40-55MHz band) as part of VULKAN project for early warning of natural hazards are discussed.

  13. From the street to the brain: neurobiology of the recreational drug ?-hydroxybutyric acid

    Microsoft Academic Search

    C. Guin Ting Wong; K. Michael Gibson; O. Carter Snead

    2004-01-01

    ?-Hydroxybutyric acid (GHB) is a short-chain fatty acid that occurs naturally in the mammalian brain and is formed primarily from the precursor ?-aminobutyric acid (GABA). The properties of GHB suggest that it has a neuromodulatory role in the brain and has the ability to induce several pharmacological and behavioral effects. GHB has been used clinically as an anesthetic and to

  14. The molecular evolution of the allatostatin precursor in cockroaches

    E-print Network

    Belles, Xavier

    The molecular evolution of the allatostatin precursor in cockroaches XAVIER BELLE´Sa , LAURIE A that specify the preproallatostatin precursor for the cockroaches, Blatta orientalis, Blattella germanica punctata and Periplaneta americana reported previously. The precursors of all these cockroach species

  15. A Population of Oligodendrocytes Derived From Multipotent Neural Precursor Cells

    E-print Network

    Manitoba, University of

    A Population of Oligodendrocytes Derived From Multipotent Neural Precursor Cells Expresses, Georgia Because oligodendrocytes and their precursors possess receptors for classical transmitters in oligodendrocyte function. We used mitogen- proliferated multipotent neuroepithelial precursors (neurospheres

  16. 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.

  17. Optical precursor fields in nonlinear pulse dynamics.

    PubMed

    Palombini, Chris L; Oughstun, Kurt E

    2010-10-25

    Under certain conditions, ultrashort pulse dynamics in a linear dispersive medium with absorption result in the appearance of optical precursors that dominate the pulse evolution for large propagation distances as the peak amplitude in the initial pulse spectrum decays exponentially. The effects of a nonlinear medium response on this precursor formation is considered using the split-step Fourier method. Comparison of the nonlinear pulse evolution when the full dispersion is used to that when a quadratic Taylor series approximation of the wave number is used shows that the group velocity approximation misses the precursor fields entirely. PMID:21164652

  18. 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.

  19. Trends in bioanalytical methods for the determination and quantification of club drugs: 2000-2010.

    PubMed

    Brown, Stacy D; Melton, Tyler C

    2011-01-01

    The term 'club drug' can be loosely defined as any substance used to enhance social settings. Such drugs are commonly found at raves or similar all-night dance parties and include methamphetamine, 3,4-methylenedioxymethamphetamine, gamma-hydroxybutyrate (GHB), ketamine (KET), and flunitrazepam (FLU). These drugs have potentially dangerous side effects including hallucinations, paranoia, amnesia and hyperthermia. In addition, GHB, KET and FLU are considered predatory drugs due to their roles in drug-facilitated sexual assault. Forensic and regulatory agencies routinely have the need for determination and accurate quantification of these drugs in biological fluids, especially in cases of mortality or criminal investigations. This review presents the chromatographic and spectroscopic methods published for such analyses over the last decade, including sample preparation techniques and validation data. PMID:21061455

  20. Precursor in cotranslational secretion of diphtheria toxin.

    PubMed Central

    Smith, W P; Tai, P C; Murphy, J R; Davis, B D

    1980-01-01

    By extracellular labeling of peptides of intact Corynebacterium diphtheriae, followed by fractionation of the cells and chain completion by isolated polysomes, it is shown that diphtheria toxin is formed and secreted cotranslationally by membrane-bound polysomes; free polysomes from none. Moreover, when the chains on these polysomes were completed in vitro, in the absence of membrane they were found to include not only diphtheria toxin of a molecular weight of 62,000, but also a larger precursor of a molecular weight of 68,000. The precursor was identified by several properties: immune precipitation; conversion into toxin fragments A and B; adenosine diphosphate ribosyl-transferase activity after activation with trypsin; and cleavage to 62,000 daltons by membrane enzymes. The precursor yields an N-terminal A fragment with a broadened molecular weight distribution, compared with that from authentic toxin, thus supporting the expectation that the extra segment of the precursor is N-terminal. PMID:6243620

  1. Optical precursor fields in nonlinear pulse dynamics

    E-print Network

    Oughstun, Kurt

    of a nonlinear medium response on this precursor formation is considered using the split-step Fourier method in the classic research by Sommerfeld [1] and Brillouin [2, 3] based on Debye's steepest descent method [4

  2. Long range transport of acid rain precursors

    E-print Network

    Fay, James A.

    1983-01-01

    A model of the long range transport of primary and secondary pollutants derived by Fay and Rosenzweig (1) is applied to the problem of the transport of acid rain precursors. The model describes the long term average (annual ...

  3. Hydridosiloxanes as precursors to ceramic products

    DOEpatents

    Blum, Yigal D. (San Jose, CA); Johnson, Sylvia M. (Piedmont, CA); Gusman, Michael I. (Palo Alto, CA)

    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.

  4. Precursors and prediction of catastrophic avalanches

    E-print Network

    Srutarshi Pradhan; Bikas K. Chakrabarti

    2006-03-23

    In this work we review the precursors of catastrophic avalanches (global failures) in several failure models, namely (a) Fiber Bundle Model (FBM), (b) Random Fuse Model (RFM), (c) Sandpile Models and (d) Fractal Overlap Model. The precursor parameters identified here essentially reflect the growing correlations within such systems as they approach their respective failure points. As we show, often they help us to predict the global failure points in advance.

  5. 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.

  6. Precursors to regulatory peptides: their proteolytic processing

    Microsoft Academic Search

    P. C. Andrews; K. Brayton; J. E. Dixon

    1987-01-01

    Summary Precursors to regulatory peptides undergo maturation processes which include protelytic processing. The enzymes involved in this process remove the hydrophobic peptide located at the amino-terminus of the precursor. Endoprotease cleavage also occurs at single and two adjacent basic residues, this is followed by a removal of basic residues located at the C-terminus of the peptides by a carboxypeptidase-like enzyme.

  7. Ionospheric precursors for crustal earthquakes in Italy

    Microsoft Academic Search

    L. Perrone; L. P. Korsunova; A. V. Mikhailov

    2010-01-01

    Crustal earthquakes with magnitude 6.0>M>=5.5 observed in Italy for the period 1979-2009 including the last one at L'Aquila on 6 April 2009 were considered to check if the earlier obtained relationships for ionospheric precursors for strong Japanese earthquakes are valid for the Italian moderate earthquakes. The ionospheric precursors are based on the observed variations of the sporadic E-layer parameters (h'Es,

  8. GRB Precursors in the Fallback Collapsar Scenario

    E-print Network

    Xiang-Yu Wang; Peter Meszaros

    2007-08-27

    Precursor emission has been observed in a non-negligible fraction of gamma-ray bursts.The time gap between the precursor and the main burst extends in some case up to hundreds of seconds, such as in GRB041219A, GRB050820A and GRB060124. Both the origin of the precursor and the large value of the time gap are controversial. Here we investigate the maximum possible time gaps arising from the jet propagation inside the progenitor star, in models which assume that the precursor is produced by the jet bow shock or the cocoon breaking out of the progenitor. Due to the pressure drop ahead of the jet head after it reaches the stellar surface, a rarefaction wave propagates back into the jet at the sound speed, which re-accelerates the jet to a relativistic velocity and therefore limits the gap period to within about ten seconds. This scenario therefore cannot explain gaps which are hundreds of seconds long. Instead, we ascribe such long time gaps to the behavior of the central engine, and suggest a fallback collapsar scenario for these bursts. In this scenario, the precursor is produced by a weak jet formed during the initial core collapse, possibly related to MHD processes associated with a short-lived proto-neutron star, while the main burst is produced by a stronger jet fed by fallback accretion onto the black hole resulting from the collapse of the neutron star. We have examined the propagation times of the weak precursor jet through the stellar progenitor. We find that the initial weak jet can break out of the progenitor in a time less than ten seconds (a typical precursor duration) provided that it has a moderately high relativistic Lorentz factor \\Gamma>=10 (abridged).

  9. 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.

  10. Germanium nanowire synthesis using solid precursors

    NASA Astrophysics Data System (ADS)

    Aksoy, Burcu; Kalay, Yunus Eren; Unalan, Husnu Emrah

    2014-04-01

    We report on the synthesis of single crystalline, high aspect ratio germanium (Ge) nanowires (NWs) by vapor transport method using three different solid powder precursors. Investigated precursors were either powder like germanium or powder mixtures like germanium dioxide with carbon and germanium iodide with germanium. As-grown NWs were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-Ray diffraction (XRD) and X-Ray photoelectron spectroscopy (XPS) to obtain structural information. The effect of temperature and pressure on the diameter and morphology of the NWs were determined. Both pressure and temperature were found to increase the diameter of the NWs independent of precursor type. Growth direction of the NWs was found to be the same while clear differences in the morphology and surrounding oxide layer thickness were observed with different precursors. Oxide layer removal via hydrobromic acid treatment was also realized. Results provided in this paper allow the basis for optimizing the synthesis of Ge NWs using solid precursors.

  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. Organoindium azides: new precursors to indium nitride

    Microsoft Academic Search

    Roland A. Fischer; Harald Sussek; Alexander Miehr; Hans Pritzkow; Eberhard Herdtweck

    1997-01-01

    The synthesis, properties and the molecular structure in the solid state of triazido(tripyridino)indium (1), the mixed coordination polymer {(CF3SO3)In[(CH2)3NMe2)]2(?-N3)In[(CH2)3NMe2)]2}. (2) and the polymeric monoazide {(N3)In[(CH2)3NMe2)]2} (3) are reported. Some aspects of the precursor chemistry of 1–3 related to the synthesis of InN thin films are discussed, with special emphasis on the aspect of the accessible chemical purity of the precursors.

  13. Nonlinear magnetohydrodynamics of edge localized mode precursors

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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 ?pr e˜x1 /3???,i n 2 /3n , with x position in radial direction, ?? ?,i n strength of initial perturbation, and n toroidal mode number.

  14. High-Solids Polyimide Precursor Solutions

    NASA Technical Reports Server (NTRS)

    Chuang, Chun-Hua (Inventor)

    2004-01-01

    The invention is a highly concentrated stable solution of polymide precursors (monometers) having a solids content ranging from about 80 to 98 percent by weight in lower aliphatic alcohols i.e. methyl and/or ethylalcohol. the concentrated polyimide precursos solution comparisons effective amounts of at least one aromatic diamine, at least one aromatic dianhydride, and a monofunctional endcap including monoamines, monoanhydrides and lower alkyl esters of said monoanhydrides. These concentrated polyimide precursor solutions are particularly useful for the preparation of fibrous prepregs and composites for use in structural materials for military and civil applications.

  15. Scavenging of carbonyl sulfide precursor in the atmosphere by precipitation

    NASA Astrophysics Data System (ADS)

    Mu, Yujing; Xu, Zhu

    2009-02-01

    Twenty-eight precipitation samples were collected in Beijing during the whole year of 2006-2007 and analyzed for the initial dissolved carbonyl sulfide (COS) (9.4-40.3 ng L-1) and the photochemical production of COS (13.7-146.5 ng L-1) by UV radiation around 365 nm. The concentration of COS precursor(s) in this study was designated as the COS concentration produced by the UV irradiation (16 fluorescent lamps, 30 W for each) for 2.5 hours. The seasonal variation of COS precursor(s) concentration in the collected precipitation samples showed that the maximum values appeared during the winter and the lowest during the summer. The decrease in the concentration of COS precursor(s) during a sequential rain event implied that precipitation might scavenge COS precursor(s) in the atmosphere. The high negative correlation (r = -0.75, p = 0.05) between rainfall intensity and the concentration of COS precursor(s) also revealed that precipitation might act as a sink for atmospheric COS precursor(s). Significant amount of COS precursor(s) in the atmosphere was also first observed, with high values at night and early morning and the minimum at noon.

  16. Simple, scientific syntheses with common catalyst precursors

    Microsoft Academic Search

    L. Jiao; Y. Zha; X. Hao; J. R. Regalbuto

    2006-01-01

    We have developed the impregnation strategy of “strong electrostatic adsorption” ( which can yield ultra-small metal particles with a simple impregnation process. The key is to perform the impregnation at the pH which maximizes electrostatic interactions between the substrate and the adsorbing metal comples. The overarching hypothesis of the Sea approach is that the high dispersion of strongly adsorbed precursors

  17. The amyloid precursor protein: beyond amyloid

    Microsoft Academic Search

    Hui Zheng; Edward H Koo

    2006-01-01

    The amyloid precursor protein (APP) takes a central position in Alzheimer's disease (AD) pathogenesis: APP processing generates the ?-amyloid (A?) 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

  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. 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.

  20. GRB Precursors in the Fallback Collapsar Scenario

    E-print Network

    Wang, X Y; Wang, Xiang-Yu; Meszaros, Peter

    2007-01-01

    Precursor emission has been observed in a non-negligible fraction of gamma-ray bursts, the time gap between the precursor and the main burst extending up to hundreds of seconds in some cases, such as in GRB041219A, GRB050820A and GRB060124. We have investigated the maximum possible time gaps arising from the jet propagation inside the progenitor star, in models which assume that the precursor is produced by the jet bow shock or the cocoon breaking out of the progenitor. Due to the pressure drop ahead of the jet head after it reaches the stellar surface, a rarefaction wave propagates back into the jet at the sound speed, which re-accelerates the jet to a relativistic velocity and therefore limits the gap period to within about ten seconds. This scenario therefore cannot explain gaps which are hundreds of seconds long. Instead, we ascribe such long time gaps to the behavior of the central engine, and suggest a fallback collapsar scenario for these bursts. In this scenario, the precursor is produced by a weak je...

  1. 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.

  2. 76 FR 77016 - Controlled Substances: Final Adjusted Aggregate Production Quotas for 2011

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-09

    ...fentanyl, gamma hydroxybutyric acid, hydrocodone, meperidine, methadone...diphenoxylate, gamma hydroxybutyric acid, meperidine, and pentobarbital required...expressed in grams of anhydrous acid or base, as...

  3. Study of the precursor and non-precursor implosion regimes in wire array Z-pinches

    SciTech Connect

    Papp, D.; Ivanov, V. V.; Anderson, A. A.; Altemara, S. D.; Talbot, B. R. [University of Nevada, Reno, Reno, Nevada 89507 (United States); Jones, B. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States); Haboub, A. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2012-09-15

    Star-like and closely spaced nested wire array configurations were investigated in precursor and non-precursor implosions. Closely spaced nested cylindrical arrays have inner and outer arrays with equal wire numbers, and inner and outer wires aligned to each other. The gap between the outer and inner wires is not more than 1 mm. Calculation of magnetic fields shows that the small gap results in a reversed, outward j Multiplication-Sign B force on the inner wires. Closely spaced arrays of 6-16 wires with outer diameter of 16 mm and with gaps of {Delta}R = 0.25-1 mm were tested. 6-8-wire arrays with a gap of {Delta}R = 0.4-1 mm imploded without precursor, but precursor was present in loads with 12-16 wires and {Delta}R = 0.25-1 mm. Implosion dynamics of closely spaced arrays was similar to that of star-like arrays. Implosion time was found to decrease with decreased wire numbers. Star array configurations were designed with a numerical scheme to implode with or without precursor. The lack of precursor resulted in a marginal improvement in total x-ray yield and power, and up to 20% increase in Al K-shell yield. The Al K-shell radiated energy was found to increase with decreasing the number of arrays in closely spaced and star-like wire arrays.

  4. 40 CFR 766.38 - Reporting on precursor chemical substances.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Identification of precursor chemical substances. Precursor chemical substances are produced...HDFs, but their molecular structure is conducive to HDD/HDF...are used to produce other chemicals or products. The...

  5. 40 CFR 766.38 - Reporting on precursor chemical substances.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Identification of precursor chemical substances. Precursor chemical substances are produced...HDFs, but their molecular structure is conducive to HDD/HDF...are used to produce other chemicals or products. The...

  6. 40 CFR 766.38 - Reporting on precursor chemical substances.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Identification of precursor chemical substances. Precursor chemical substances are produced...HDFs, but their molecular structure is conducive to HDD/HDF...are used to produce other chemicals or products. The...

  7. 40 CFR 766.38 - Reporting on precursor chemical substances.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Identification of precursor chemical substances. Precursor chemical substances are produced...HDFs, but their molecular structure is conducive to HDD/HDF...are used to produce other chemicals or products. The...

  8. 40 CFR 766.38 - Reporting on precursor chemical substances.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Identification of precursor chemical substances. Precursor chemical substances are produced...HDFs, but their molecular structure is conducive to HDD/HDF...are used to produce other chemicals or products. The...

  9. Optical Precursors in Rubidium Vapor and Their Relation to Superradiance 

    E-print Network

    Yang, Wenlong

    2012-10-19

    Optical precursor is the sharp optical pulse front that does not show delay in absorptive media. In this thesis, optical precursor behavior in rubidium (Rb) vapor was investigated in the picoseconds regime. An amplified femtosecond laser was shaped...

  10. Optical Precursors in Rubidium Vapor and Their Relation to Superradiance

    E-print Network

    Yang, Wenlong

    2012-10-19

    Optical precursor is the sharp optical pulse front that does not show delay in absorptive media. In this thesis, optical precursor behavior in rubidium (Rb) vapor was investigated in the picoseconds regime. An amplified femtosecond laser was shaped...

  11. 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.

  12. Calculations of precursor propagation in dispersive dielectrics.

    SciTech Connect

    Bacon, Larry Donald

    2003-08-01

    The present study is a numerical investigation of the propagation of electromagnetic transients in dispersive media. It considers propagation in water using Debye and composite Rocard-Powles-Lorentz models for the complex permittivity. The study addresses this question: For practical transmitted spectra, does precursor propagation provide any features that can be used to advantage over conventional signal propagation in models of dispersive media of interest? A companion experimental study is currently in progress that will attempt to measure the effects studied here.

  13. Biochar as a precursor of activated carbon

    Microsoft Academic Search

    R. Azargohar; A. K. Dalai

    2006-01-01

    Biochar was evaluated as a precursor of activated carbon. This product was produced by chemical activation using potassium\\u000a hydroxide. The effects of operating conditions of activation process, such as temperature, activating agent to biochar mass\\u000a ratio, and nitrogen flow rate, on the textural and chemical properties of the product were investigated. Activated carbon\\u000a produced by this method has internal surface

  14. Optical Synchrotron Precursors of Radio Hypernovae

    NASA Astrophysics Data System (ADS)

    Nakauchi, Daisuke; Kashiyama, Kazumi; Nagakura, Hiroki; Suwa, Yudai; Nakamura, Takashi

    2015-06-01

    We examine the bright radio synchrotron counterparts of low-luminosity gamma-ray bursts and relativistic supernovae (SNe) and find that they can be powered by spherical hypernova (HN) explosions. Our results imply that radio-bright HNe are driven by relativistic jets that are choked deep inside the progenitor stars or quasi-spherical magnetized winds from fast-rotating magnetars. We also consider the optical synchrotron counterparts of radio-bright HNe and show that they can be observed as precursors several days before the SN peak with an r-band absolute magnitude of {{M}r}? -14 mag. While previous studies suggested that additional trans-relativistic components are required to power the bright radio emission, we find that they overestimated the energy budget of the trans-relativistic component by overlooking some factors related to the minimum energy of non-thermal electrons. If an additional trans-relativistic component exists, then a much brighter optical precursor with {{M}r}? -20 mag can be expected. Thus, the scenarios of radio-bright HNe can be distinguished by using optical precursors, which can be detectable from ? 100 Mpc by current SN surveys like the Kiso SN Survey, Palomar Transient Factory, and Panoramic Survey Telescope & Rapid Response System.

  15. 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.

  16. 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

  17. Colorectal serrated pathway cancers and precursors.

    PubMed

    O'Brien, Michael J; Zhao, Qing; Yang, Shi

    2015-01-01

    The serrated pathway (SP) can be viewed as two parallel, but partially overlapping, arrays of colorectal precursor lesions, and their respective endpoint carcinomas, that are distinct from those of the conventional adenoma-carcinoma sequence (APC-pathway). In this review we focus at the outset on the clinical impact, pathological features, molecular genetics and biological behaviours of the various SP cancers. Then we summarize the clinicopathological features, classification and molecular profiles of the two main precursor lesions that anchor the respective pathways: (i) sessile serrated adenoma/polyp (SSA/P), also called sessile serrated lesion (SSL), and (ii) traditional serrated adenoma (TSA). Activating mutations of the RAS-RAF-MAPK pathway initiate and sustain the lesions of the SP, and CpG island methylation of the promoter regions of tumour suppressor and DNA repair genes play the major role in their neoplastic progression. The SP includes microsatellite stable (MSS) carcinomas that are among the most biologically aggressive colorectal carcinomas (CRC), and also accounts for the great preponderance of sporadic hypermutated, mismatch repair (MMR)-deficient or microsatellite instable (MSI) CRC. The identification, removal and appropriate classification of at-risk SP precursors and surveillance of individuals who harbour these lesions present a challenge and opportunity for CRC prevention and mortality reduction. PMID:25263173

  18. 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

  19. 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

  20. Scalar model for frictional precursors dynamics

    E-print Network

    Alessandro Taloni; Andrea Benassi; Stefan Sandfeld; Stefano Zapperi

    2014-09-26

    Recent experiments indicate that frictional sliding occurs by the 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 such 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 the 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 the transition to sliding, and the normal and shear internal stress distributions close to the slider-substrate interface. Moreover, it allows to assess which experimental 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, which helps to explain why earthquake forecasting methods based only on accumulated slip and Coulomb stress monitoring are often ineffective.

  1. 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.

  2. 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.

  3. Optical precursors with self-induced transparency

    SciTech Connect

    Macke, Bruno; Segard, Bernard [Laboratoire de Physique des Lasers, Atomes et Molecules (PhLAM), Centre d'Etudes et de Recherches Lasers et Applications, CNRS et Universite Lille 1, F-59655 Villeneuve d'Ascq (France)

    2010-01-15

    Optical Sommerfeld-Brillouin precursors significantly ahead of a main field of comparable amplitude have been recently observed in an opaque medium with an electromagnetically induced transparency window [Wei et al., Phys. Rev. Lett. 103, 093602 (2009)]. We theoretically analyze in this article the somewhat similar results obtained when the transparency is induced by the propagating field itself and we establish an approximate analytic expression of the time delay of the main-field arrival, which fits fairly well the result obtained by numerically solving the Maxwell-Bloch equations.

  4. Fluid imbibition in paper fibers: Precursor front

    NASA Astrophysics Data System (ADS)

    de Azevedo, Eduardo N.; Alme, Lars R.; Engelsberg, M.; Fossum, Jon Otto; Dommersnes, Paul

    2008-12-01

    We employ nuclear magnetic resonance imaging to study water penetration in cylindrical blocks of unsized paper prepared under different molding pressures. From the measured kinetics of the imbibition profiles, we determine the dependence of the effective transport diffusivity upon degree of saturation of the pores by the penetrating fluid. In general, the transport process is found to be non-Fickian and we discuss different methods of data analysis adapted to this situation. The effective transport diffusivity vividly captures the presence of a precursor front, consisting of fluid in partially filled pores, with a much higher effective diffusivity than that of fluid in largely saturated pores.

  5. 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.

  6. Study of tectonic earthquake precursors by geodetic methods

    SciTech Connect

    Sigalov, V.M.

    1985-02-01

    Deformations of the Earth's surface which can be revealed by geodetic methods are among the most reliable earthquake precursors. A brief list is presented of geodetic leveling methods which have revealed the precursors of several earthquakes. To confirm the accuracy of determination of precursors of earthquakes based on the results of repeated leveling in epicenter zones and observations at Alma-Ata, the magnitudes of 7 earthquakes which occurred in northern Tien Shan during measurement of tectonic precursors were calculated and compared to valves based on seismologic measurements. The agreement found is satisfactory. A scientifically well-founded program of tectonic movements by geodetic methods in the northern Tien Shan has thus established the presence of tectonic precursors of earthquakes, determined the distances over which they are manifested and shown the possiblity of using the results of geodetic measurements in combiantion with geophysical and seismologic data to estimate the possible time of appearance of earthquake precursors.

  7. The Role of Circulating Bone Cell Precursors in Fracture Healing

    Microsoft Academic Search

    Patrizia D’Amelio; Maria Angela Cristofaro; Anastasia Grimaldi; Marco Ravazzoli; Fernanda Pluviano; Elena Grosso; Gian Piero Pescarmona; Giovanni Carlo Isaia

    2010-01-01

    Fracture healing is a complex process that involves several cell types; as a previous report suggested an increase in osteoblast\\u000a (OB) precursors in peripheral blood during this process, this paper examines the role of circulating bone cell precursors\\u000a in this process in the light of a prior suggestion that OB precursors are increased. Nine healthy men less than 60 years old

  8. 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

  9. 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.

  10. Nanostructured carbonaceous materials from molecular precursors.

    PubMed

    Hoheisel, Tobias N; Schrettl, Stephen; Szilluweit, Ruth; Frauenrath, Holger

    2010-09-01

    Nanostructured carbonaceous materials, that is, carbon materials with a feature size on the nanometer scale and, in some cases, functionalized surfaces, already play an important role in a wide range of emerging fields, such as the search for novel energy sources, efficient energy storage, sustainable chemical technology, as well as organic electronic materials. Furthermore, such materials might offer solutions to the challenges associated with the on-going depletion of nonrenewable energy resources or climate change, and they may promote further breakthroughs in the field of microelectronics. However, novel methods for their preparation will be required that afford functional carbon materials with controlled surface chemistry, mesoscopic morphology, and microstructure. A highly promising approach for the synthesis of such materials is based on the use of well-defined molecular precursors. PMID:20661971

  11. Silsesquioxanes as precursors to ceramic composites

    NASA Technical Reports Server (NTRS)

    Hurwitz, F. I.; Hyatt, L.; Gorecki, J.; D'Amore, L.

    1987-01-01

    Silsesquioxanes having the general structure RSiO(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 source 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.

  12. 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.

  13. Mars MetNet Precursor Mission Status

    NASA Astrophysics Data System (ADS)

    Harri, A.-M.; Aleksashkin, S.; Guerrero, H.; Schmidt, W.; Genzer, M.; Vazquez, L.; Haukka, H.

    2013-09-01

    We are developing a new kind of planetary exploration mission for Mars 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). The scientific payload of the Mars MetNet Precursor [1] mission is divided into three categories: Atmospheric instruments, Optical devices and Composition and structure devices. Each of the payload instruments will provide significant insights in to the Martian atmospheric behavior. The key technologies of the MetNet Lander have been qualified and the electrical qualification model (EQM) of the payload bay has been built and successfully tested.

  14. Diamond films grown from fullerene precursors

    SciTech Connect

    Gruen, D.M.; Zuiker, C.D.; Krauss, A.R.

    1995-07-01

    Fullerene precursors have been shown to result in the growth of diamond films from argon microwave plasmas. In contradistinction to most diamond films grown using conventional methane-hydrogen mixtures, the fullerene-generated films are nanocrystalline and smooth on the nanometer scale. They have recently been shown to have friction coefficients approaching the values of natural diamond. It is clearly important to understand the development of surface morphology during film growth from fullerene precursors and to elucidate the factors leading to surface roughness when hydrogen is present in the chemical vapor deposition (CVD) gas mixtures. To achieve these goals, we are measuring surface reflectivity of diamond films growing on silicon substrates over a wide range of plasma processing conditions. A model for the interpretation of the laser interferometric data has been developed, which allows one to determine film growth rate, rms surface roughness, and bulk losses due to scattering and absorption. The rms roughness values determined by reflectivity are in good agreement with atomic force microscope (AFM) measurements. A number of techniques, including high-resolution transmission electron microscopy (HRTEM) and near-edge x-ray absorption find structure (NEXAFS) measurements, have been used to characterize the films. A mechanism for diamond-film growth involving the C{sub 2} molecule as a growth species will be presented. The mechanism is based on (1) the observation that the optical emission spectra of the fullerene- containing plasmas are dominated by the Swan bands of C{sub 2} and (2) the ability of C{sub 2} to insert directly into C-H and C-C bonds with low activation barriers, as shown by recent theoretical calculations of reactions of C{sub 2} with carbon clusters.

  15. 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.

  16. 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…

  17. A second cytotoxic proteolytic peptide derived from amyloid ?-protein precursor

    Microsoft Academic Search

    Daniel C. Lu; Shahrooz Rabizadeh; Sreeganga Chandra; Rana F. Shayya; Lisa M. Ellerby; Xin Ye; Guy S. Salvesen; Edward H. Koo; Dale E. Bredesen

    2000-01-01

    The amyloid ?-protein precursor gives rise to the amyloid ?-protein, the principal constituent of senile plaques and a cytotoxic fragment involved in the pathogenesis of Alzheimer disease. Here we show that amyloid ?-protein precursor was proteolytically cleaved by caspases in the C terminus to generate a second unrelated peptide, called C31. The resultant C31 peptide was a potent inducer of

  18. Topochemical Synthesis of Three-Dimensional Perovskites from Lamellar Precursors

    E-print Network

    Topochemical Synthesis of Three-Dimensional Perovskites from Lamellar Precursors Raymond E. Schaak-dimensional perovskites from lamellar Dion-Jacobson and Ruddlesden-Popper precursors was demonstrated. The method involves) and reduced in hydrogen to form the SrTiO3-type perovskites AEu2Ti2NbO9. Similarly, K2Eu2Ti3O10, a three

  19. 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…

  20. Human embryonic epidermis contains a diverse Langerhans cell precursor pool.

    PubMed

    Schuster, Christopher; Mildner, Michael; Mairhofer, Mario; Bauer, Wolfgang; Fiala, Christian; Prior, Marion; Eppel, Wolfgang; Kolbus, Andrea; Tschachler, Erwin; Stingl, Georg; Elbe-Bürger, Adelheid

    2014-02-01

    Despite intense efforts, the exact phenotype of the epidermal Langerhans cell (LC) precursors during human ontogeny has not been determined yet. These elusive precursors are believed to migrate into the embryonic skin and to express primitive surface markers, including CD36, but not typical LC markers such as CD1a, CD1c and CD207. The aim of this study was to further characterize the phenotype of LC precursors in human embryonic epidermis and to compare it with that of LCs in healthy adult skin. We found that epidermal leukocytes in first trimester human skin are negative for CD34 and heterogeneous with regard to the expression of CD1c, CD14 and CD36, thus contrasting the phenotypic uniformity of epidermal LCs in adult skin. These data indicate that LC precursors colonize the developing epidermis in an undifferentiated state, where they acquire the definitive LC marker profile with time. Using a human three-dimensional full-thickness skin model to mimic in vivo LC development, we found that FACS-sorted, CD207(-) cord blood-derived haematopoietic precursor cells resembling foetal LC precursors but not CD14(+)CD16(-) blood monocytes integrate into skin equivalents, and without additional exogenous cytokines give rise to cells that morphologically and phenotypically resemble LCs. Overall, it appears that CD14(-) haematopoietic precursors possess a much higher differentiation potential than CD14(+) precursor cells. PMID:24496618

  1. Neural precursor lineages specify distinct neocortical pyramidal neuron types.

    PubMed

    Tyler, William A; Medalla, Maria; Guillamon-Vivancos, Teresa; Luebke, Jennifer I; Haydar, Tarik F

    2015-04-15

    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

  2. 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

  3. 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.

  4. Thin-film flows without precursors

    NASA Astrophysics Data System (ADS)

    Juanes, Ruben; Cueto-Felgueroso, Luis; Szulczewski, Michael

    2012-11-01

    The flow of thin films over flat surfaces has been the subject of much theoretical, experimental and computational research. Under the lubrication approximation, the classical mathematical model for these flows takes the form of a nonlinear fourth-order PDE, where the fourth-order term models the effect of surface tension. This classical model, however, effectively assumes that the film is perfectly wetting to the substrate and, therefore, does not capture the partial wetting regime. Partial wetting is responsible for stopping the spread of a liquid puddle, and for pinning the contact line of a viscous liquid down an incline, controlling the morphology of the fingering pattern that ensues. Here, we extend our recent work on macroscopic phase-field modeling of two-phase flow in a capillary tube to thin-film flows with partial wetting. Our model naturally accounts for the dynamic contact angle at the contact line, and therefore permits modeling thin-film flows without invoking a precursor film, leading to compactly-supported solutions. We model the statics and dynamics of a liquid puddle, and the fingering behavior of flow down an incline. We compare model predictions with experiments of thin-film flows both on a horizontal plane and down an incline, for different contact angles.

  5. 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.

  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. Earth Observing System precursor data sets

    NASA Astrophysics Data System (ADS)

    Mah, Grant R.; Eidenshink, Jeff C.; Sheffield, K. W.; Myers, Jeffrey S.

    1993-08-01

    The Land Processes Distributed Active Archive Center (DAAC) is archiving and processing precursor data from airborne and spaceborne instruments such as the thermal infrared multispectral scanner (TIMS), the NS-001 and thematic mapper simulators (TMS), and the advanced very high resolution radiometer (AVHRR). The instrument data are being used to construct data sets that simulate the spectral and spatial characteristics of the advanced spaceborne thermal emission and reflection radiometer (ASTER) and the moderate resolution imaging spectrometer (MODIS) flight instruments scheduled to be flown on the EOS-AM spacecraft. Ames Research Center has developed and is flying a MODIS airborne simulator (MAS), which provides coverage in both MODIS and ASTER bands. A simulation of an ASTER data set over Death Valley, California has been constructed using a combination of TMS and TIMS data, along with existing digital elevation models that were used to develop the topographic information. MODIS data sets are being simulated by using MAS for full-band site coverage at high resolution and AVHRR for global coverage at 1 km resolution.

  8. 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 ?g-chloroform /mg-C were generated during the bacterial chlorination, in similar order of magnitude to that generated by humic acid (previously reported as 78 ?g-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.

  9. A fission-powered interstellar precursor mission

    NASA Astrophysics Data System (ADS)

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

    1999-01-01

    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 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.

  10. Combinatorial Rules of Precursor Specification Underlying Olfactory Neuron Diversity

    PubMed Central

    Li, Qingyun; Ha, Tal Soo; Okuwa, Sumie; Wang, Yiping; Wang, Qian; Millard, S. Sean; Smith, Dean P.; Volkan, Pelin Cayirlioglu

    2015-01-01

    Summary Background Sensory neuron diversity ensures optimal detection of the external world and is a hallmark of sensory systems. An extreme example is the olfactory system, as individual olfactory receptor neurons (ORNs) adopt unique sensory identities by typically expressing a single receptor gene from a large genomic repertoire. In Drosophila, about 50 different ORN classes are generated from a field of precursor cells, giving rise to spatially restricted and distinct clusters of ORNs on the olfactory appendages. Developmental strategies spawning ORN diversity from an initially homogeneous population of precursors are largely unknown. Results Here we unravel the nested and binary logic of the combinatorial code that patterns the decision landscape of precursor states underlying ORN diversity in the Drosophila olfactory system. The transcription factor Rotund (Rn) is a critical component of this code that is expressed in a subset of ORN precursors. Addition of Rn to preexisting transcription factors that assign zonal identities to precursors on the antenna subdivides each zone and almost exponentially increases ORN diversity by branching off novel precursor fates from default ones within each zone. In rn mutants, rn-positive ORN classes are converted to rn-negative ones in a zone-specific manner. Conclusions We provide a model describing how nested and binary changes in combinations of transcription factors could coordinate and pattern a large number of distinct precursor identities within a population to modulate the level of ORN diversity during development and evolution. PMID:24268416

  11. Schwann Cell-Like Differentiation by Adult Oligodendrocyte Precursor Cells Following Engraftment

    E-print Network

    Harkema, Susan

    Schwann Cell-Like Differentiation by Adult Oligodendrocyte Precursor Cells Following Engraftment demyelination; remyelination; noggin; adult oligodendrocyte precursor cell; astrocyte; spinal cord ABSTRACT spinal-cord- derived oligodendrocyte precursor cells (adult OPCs). In the present study, we demonstrate

  12. Association between narcotic use and anabolic-androgenic steroid use among American adolescents.

    PubMed

    Denham, Bryan E

    2009-01-01

    Drawing on the data gathered in the 2006 Monitoring the Future study of American youth, the present research examines associations between use of narcotics and use of anabolic-androgenic steroids (AASs) among high-school seniors (n = 2,489). With independent measures and controls including sex, race, media exposure, socializing with friends, participation in recreational and school-sponsored sports, perceptions of drug use among professional athletes, and perceptions of steroid use among close friends, binary logistic regression analyses revealed significant associations between AAS use and the use of alcohol, crack cocaine, Vicodin, gamma-hydroxybutyrate (GHB), Ketamine, and Rohypnol. While use of both AASs and the narcotic drugs generally did not eclipse 5% of the sample, the numbers extend to many thousands in larger populations. Implications for health practitioners and recommendations for future research are offered. The study's limitations are noted. PMID:20001694

  13. Methods for forming particles from single source precursors

    DOEpatents

    Fox, Robert V. (Idaho Falls, ID); Rodriguez, Rene G. (Pocatello, ID); Pak, Joshua (Pocatello, ID)

    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.

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

    NASA Astrophysics Data System (ADS)

    Hong, Guo; Wu, Qi-Hui; Wang, Chundong; Ren, Jianguo; Xu, Tingting; Zhang, Wenjun; Lee, Shuit-Tong

    2013-02-01

    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 (F4-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 F4-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.

  15. 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

  16. 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.

  17. Metal Precursors and Reduction in Renazzo Chondrules

    NASA Astrophysics Data System (ADS)

    Zanda, B.; Hewins, R. H.; Bourot-Denise, M.

    1993-07-01

    The positive Co-Ni correlation and Cr, P contents of metal in CR chondrites have generally been taken to indicate their primitive nature, probably inherited from condensation [1,2]. Si in the metal of primitive chondrites has also been reported and interpreted as a condensation heritage [3,4]. However, Cr, P, and Si (dissolved or in the form of inclusions) in metal of any CR chondrule generally fall within a +-10% range, though large interchondrule variations exist [5]. We have shown that Cr and Si in metal are in equilibrium with Fo and En in silicates, due to the reducing conditions that prevailed during chondrule formation [6]. In the present paper, we show that the Co-Ni trend was also established during chondrule formation out of heterogeneous precursor material with a variable Co/Ni ratio. Chondrules in Renazzo are classified as highly molten (HM), in which metal has been expelled to form a mantle outside the chondrule, medium molten (MM), with metal inside and at the periphery, and with evidence for grain coalescence, and little melted (LM), in which metal is only present in the form of small blebs dispersed among the silicates. In HM chondrules, Ni and Co concentrations are extremely homogeneous, comparatively low and in the cosmic ratio. In LM chondrules, quite the opposite: Ni and Co spread over a large range and the amount of scatter increases with decreasing degree of melting of the chondrule. In addition, they do not correlate along the cosmic ratio, but show a negative correlation if any. This heterogeneity is present not only from grain to grain in these chondrules, but also in individual metal grains. Such a heterogeneity is also exhibited in Cr and P abundances that span a much larger range than the +-10% found in the other chondrules. These results indicate that chondrule formation is responsible for the homogenization of Co and Ni contents of metal grains through coalescence and mixing. The less melted objects give an idea of the nature of metal in chondrule precursors, extremely heterogeneous and fine grained (each small heterogeneous metal bleb might be the result of partial melting of one or of coalescence and imperfect mixing of a few such grains). Co and Ni in these individual grains were not in the cosmic ratio, but wide sampling of dust in each chondrule precursor insured that this ratio was attained after mixing and homogenization, as seen in HM chondrule metal grains and from mean values of Co and Ni in LM chondrules. In MM chondrules, scatter of Ni and Co data are, as expected, intermediate between those of HM and LM chondrules, but Co and Ni are close to the cosmic ratio. The scatter is mostly due to addition of variable quantities of iron in the reduction during chondrule formation, which is responsible for Cr and Si integration into metal. Further evidence of such a process can be found in the less molten of these objects, in which metal grain coalescence is limited and peripheral grains are still different from inside grains. In these cases, Co and Ni distributions are clearly bimodal, high in inside grains, low in peripheral grains. Co/Ni in these two populations are somewhat scattered around the cosmic ratio, but their means (Ni: 7.75 = +- 0.24, Co: 0.36 +- 0.04, and Ni: 4.39 +- 0.34, Co: 0.23 +- 0.02, e.g., in the case of chondrule AL1) are very close to the cosmic ratio. This is in good agreement with the low values found in the homogeneous mantle grains of HM chondrules and, as noted by Lee et al. [7], indicates that the reducing agent was external to the chondrule. Cr abundances of these peripheral metal grains, however, match Cr abundances of the interior ones in these chondrules. This indicates that the redox state of all these grains was attained simultaneously and controlled by equilibrium with chondrule silicates. Slightly more extensive reduction of the latter close to the chondrule surface that added more Fe to peripheral metal grains resulted in only a minor variation of the Cr partition coefficient: it consequently also induced Cr addition, the Cr/Fe ratio varying only marg

  18. 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...

  19. REMOVAL OF TRIHALOMETHANE PRECURSORS BY DIRECT FILTRATION AND CONVENTIONAL TREATMENT

    EPA Science Inventory

    This research examined direct filtration for the removal of trihalomethane (THM) precursors. Direct filtration pilot plant results were compared with the performance of two full scale conventional type water treatment plants. Two different water sources were studied - the Grasse ...

  20. 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...

  1. 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...

  2. Efficiency of alum coagulation for removal of trihalomethane precursors 

    E-print Network

    Shannon, Joe Dan

    1980-01-01

    EFFICIENCY OF ALUM COAGULATION FOR REMOUAL OF TRIHALOMETHANE PRECURSORS A Thesis by JOE DAN SHANNON Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE... August 1980 Major Subject: Civil Engineering EFFICIENCY OF ALUM COAGULATION FOR REMOVAL OF TRIHALOMETHANE PRECURSORS A Thesis by JOE DAN SHANNON Approved as to style and content by: (Chairman of Committee) (Member) (Memb ) (Head of Department...

  3. CIGS-based solar cells prepared from electrodeposited precursor films

    Microsoft Academic Search

    Raghu N. Bhattacharya; Mi-Kyung Oh; Youngho Kim

    Previously, we reported 15.4%-efficient [1] copper indium gallium diselenide (CIGS)-based photovoltaic devices from electrodeposited precursor films in which the final film composition was adjusted using the physical vapor deposition (PVD) method. At present, we are fabricating CIGS-based solar cells directly from electrodeposited precursor films, eliminating the expensive PVD step. Electrodeposited CIGS absorber layers are fabricated by a three-stage electrodeposition process

  4. Stacked Optical Precursors from Amplitude and Phase Modulations

    SciTech Connect

    Chen, J. F.; Feng, L.; Loy, M. M. T.; Wong, G. K. L.; Du, Shengwang [Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Jeong, Heejeong [Samsung Electronics Co., Ltd., Suwon, Gyeonggi (Korea, Republic of)

    2010-06-04

    We report the generation of stacked optical precursors from a laser beam whose amplitude or phase is modulated by sequenced on-off step waveforms. Making use of the constructive interference between the precursors produced from different steps, as well as the main field, we generate optical transient pulses having peak powers of eight times the input power with electromagnetically induced transparency in laser-cooled atoms.

  5. 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).

  6. Preparation of silicon carbide foams using polymeric precursor solutions

    Microsoft Academic Search

    X. Bao; M. R. Nangrejo; M. J. Edirisinghe

    2000-01-01

    A simple method was developed to produce silicon carbide foams using polysilane polymeric precursors. Polyurethane foams were immersed in polysilane precursor solutions to prepare pre-foams. Subsequently, these were heated in nitrogen at different temperatures in the range of 900°C to 1300°C. The silicon carbide foams produced in this manner showed well-defined open-cell structures and the struts in the foams were

  7. 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.

  8. 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

  9. 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.

  10. The Pediocin AcH Precursor Is Biologically Active

    PubMed Central

    Ray, Bibek; Schamber, Robin; Miller, Kurt W.

    1999-01-01

    The properties of the pediocin AcH precursor, prepediocin AcH, have been studied to gain insight into how producer cells may protect themselves from the activity of intracellular prebacteriocins. The native 62-amino-acid precursor and the 44-amino-acid mature species were expressed in Escherichia coli host strains that lack the leader peptide processing enzyme, PapD. Both forms inhibited the growth of the test bacterium Listeria innocua Lin11, indicating that the native precursor is biologically active. The two species also were synthesized in the context of maltose-binding protein chimeric proteins to facilitate the measurement of their relative specific activities. The chimeric form of the precursor was ?80% as active as the chimeric mature species. Of relevance to cell protection and pediocin AcH production, it was determined that the precursor is strongly susceptible to inactivation by reducing agents and to degradation by chymotrypsin and endogenous E. coli proteases. Taken together, the results indicate that the activity of prepediocin AcH may have to be controlled prior to secretion to prevent toxicity to the host. Perhaps producer cells avoid membrane damage by maintaining the precursor in a reduced inactive state or by degrading molecules whose secretion is delayed. PMID:10347002

  11. 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.

  12. 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.

  13. 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.

  14. Sensitivity and uncertainty analyses for the accident sequence precursor study

    SciTech Connect

    Modarres, M.; Cadman, T.W.; Gardner, A.R.; Lois, E.

    1985-04-01

    Sensitivity and uncertainty analyses of the Accident Sequence Precursor (ASP) report were undertaken. The sensitivity analysis was performed using a parametric study code developed by the Oak Ridge National Laboratory. The uncertainty analysis was performed using the ASAP code developed in this study and the MOCARS code developed by EGandG Idaho. The sensitivity analysis included estimation of the sensitivity of the calculated core damage frequency to the following parameters: loss of function failure and recovery factor data recommended by the Institute of Nuclear Power Operations; recovery factors; degraded function multiplier; loss of function probabilities; and vendor, reactor type, etc. The sensitivity calculations were performed for both boiling water reactor and pressurized water reactor precursors, individually. Numerous case runs were made and the results summarized. The uncertainty analysis included estimation of the 95% confidence limits on the point estimate calculations of the ASP study. Two basic approaches were used to calculate the uncertainty bounds. The procedures used and the results obtained were compared. The point estimates in the ASP study for which uncertainty limits were calculated were individual significant precursors (52 event trees, each representing one precursor) and the total core damage frequency, both including and excluding the three major precursor events.

  15. Hydrokinetic simulations of nanoscopic precursor films in rough channels

    NASA Astrophysics Data System (ADS)

    Chibbaro, S.; Biferale, L.; Binder, K.; Dimitrov, D.; Diotallevi, F.; Milchev, A.; Succi, S.

    2009-06-01

    We report on simulations of capillary filling of highly wetting fluids in nanochannels with and without obstacles. We use atomistic (molecular dynamics) and hydrokinetic (lattice Boltzmann; LB) approaches which indicate clear evidence of the formation of thin precursor films, moving ahead of the main capillary front. The dynamics of the precursor films is found to obey a square-root law like that obeyed by the main capillary front, z^2(t) \\propto t , although with a larger prefactor, which we find to take the same value for the different geometries (2D-3D) under inspection. The two methods show a quantitative agreement which indicates that the formation and propagation of thin precursors can be handled at a mesoscopic/hydrokinetic level. This can be considered as a validation of the LB method and opens the possibility of using hydrokinetic methods to explore space-time scales and complex geometries of direct experimental relevance. Then, the LB approach is used to study the fluid behaviour in a nanochannel when the precursor film encounters a square obstacle. A complete parametric analysis is performed which suggests that thin-film precursors may have an important influence on the efficiency of nanochannel-coating strategies.

  16. TEM study of diamond films grown from fullerene precursors

    SciTech Connect

    Csencsits, R.; Gruen, D.M.; Krauss, A.R.; Zuiker, C.

    1995-11-01

    Transmission Electron Microscope (TEM) techniques are applied to study the microstructure of diamond films grown from fullerene precursors. Electron diffraction and electron energy loss spectra (EELS) collected from the diamond films correspond to that of bulk diamond. Microdiffraction, high resolution images and EELS help determine that the first diamond grains that nucleate from fullerene precursors generally form on a thin amorphous carbon interlayer and seldom directly on the silicon substrate. Grain size measurements reveal nanocrystalline diamond grains. Cross section TEM images show that the nanocrystalline diamond grains are equiaxed and not columnar nor dendritic. The microstructure of small equiaxed grains throughout the film thickness is believed responsible for the very smooth surfaces of diamond films grown from fullerene precursors.

  17. 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

  18. Influence of the Precursor on Cerium Distribution over Alumina

    NASA Astrophysics Data System (ADS)

    Appel, Lucia G.; Appel, Lucia G.; Eon, J. G.; Schmal, M.

    1997-09-01

    The Ce/Al2O3 catalysts were prepared with Ce(NO3)3, (NH4)2Ce(NO3)6 and with cerium acethylacetonate precursors over alumina, by impregnation and grafting, respectively. Results have shown that the CeO2 surface area of the catalysts with the nitrate precursors is very similar but much higher on the catalysts with the acethylacetonate after grafting. The reducibility of this catalyst is better than of the catalysts with the nitrate precursor. TPR results indicate a reduction of CeO2, the formation of CeAlO3 and Ce2O3. The experimental condition employed here allows to attain saturation over alumina which is probably due to steric effects of the Ce(Acet)3 molecules.

  19. Polymer precursors to silicate ceramics: Studies of ceramic formation

    SciTech Connect

    Ober, C.K.; Martin, M.H.E.; Beecroft, L. [Cornell Univ., Ithaca, NY (United States)

    1993-12-31

    A route to silicate ceramics based on the pyrolysis of polymer precursors was investigated using high temperature X-ray diffraction. The methacrylate precursors under study have been optimized to produce forsterite, a ceramic which when doped with chromium has been shown to lase in the near infrared at wavelengths suitable for optical communication. Greatest yields occur when monomers capable of producing silicate crosslinks are introduced into the precursor compositions. The formation of forsterite occurs at those temperatures (600-800{degrees}C) producing the greatest rate of mass loss. A transient crystalline phase prior to forsterite formation was revealed by the X-ray studies. The concentration of carbon present in the sample was also observed to delay forsterite formation until higher temperatures. The effect of chromium dopant on ceramic formation will be described.

  20. Mechanisms of Gravitational Sensitivity of Osteogenic Precursor Cells

    PubMed Central

    Buravkova, L.B.; Gershovich, P.M.; Grigor?ev, 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

  1. Searching for seismic precursors in southern California with phase coherence

    NASA Astrophysics Data System (ADS)

    Hawthorne, Jessica; Ampuero, Jean-Paul

    2015-04-01

    We search for tremor-like seismic precursors to M3-6 earthquakes in southern California. We examine the seconds to minutes before each earthquake with a frequency-domain phase coherence approach. We look for precursory signals that have high phase coherence with the earthquake seismograms---after cross-correlating between two stations. This inter-station correlation eliminates much of the complexity of the source-time functions. It allows the phase coherence technique to identify signals that originate in the same location as the earthquake, even if those signals have extended source-time functions. To demonstrate this approach, we use it to analyze an emergent precursor detected by Tape et. al., 2013, prior to a M3.9 earthquake in central Alaska. In southern California, we have thus far examined 1000 earthquakes. The method successfully detects many of the previously identified foreshocks, as well as several foreshocks that are not in the catalog. However, it reveals no tremor-like seismic precursors. For most of the earthquakes, error estimates indicate that any precursors still hidden in the data should be smaller than a signal with a duration of 5 seconds and energy equivalent to a M1 earthquake. We could reduce this upper bound further by averaging the phase coherence over multiple potential precursors. However, that reduced noise floor reveals a bias that results from temporal variations in noise sources. The phase coherence of two seismograms including only noise is usually higher if the seismograms are more closely spaced in time. This causes a bias because the template earthquake seismogram includes some noise. In order to avoid this problem, we also consider an alternative template: the seismogram of an earthquake that occurs nearby but at a different time. However, this analysis is more complicated because the new template earthquake may not be entirely coherent with the earthquake with the potential precursor.

  2. Strain-stabilized precursor clusters in potassium thiocyanate

    NASA Astrophysics Data System (ADS)

    Blaschko, O.; Schranz, W.; Fally, M.; Krexner, G.; ?odziana, Z.

    1998-10-01

    We present refined diffuse neutron scattering measurements performed in the long-range-ordered phase of potassium thiocyanate (Tprecursor to the order-disorder phase transition. The diffuse intensity increases when approaching Tc from below, whereas the width remains constant in the whole long-range-ordered phase. Molecular-dynamics simulations indicate that the size of the precursor clusters is stabilized by the order-parameter-strain interactions.

  3. The interaction between microglia and neural stem/precursor cells.

    PubMed

    Su, Peng; Zhang, Jianbin; Zhao, Fang; Aschner, Michael; Chen, Jingyuan; Luo, Wenjing

    2014-10-01

    In the adult mammalian brain, neurogenesis from neural stem/precursor cell occurs within two regions, the subgranular zone (SGZ) in the dentate gyrus (DG) and the subventricular zone (SVZ) lining the lateral ventricles. The function of neural stem cell is enhanced by external stimuli, such as injury and inflammation. Microglia, as the main immune modulating cells, play important roles in the central nervous system (CNS). Recently, select discoveries reported that microglia might influence the proliferation, differentiation and survival of neural precursor cells (NPCs). Other studies revealed that NPCs might reversibly regulate the function of microglia. Accordingly, in this review we focus on the interaction between microglia and NPCs. PMID:25245208

  4. The role of aldehyde reductase AKR1A1 in the metabolism of ?-hydroxybutyrate in 1321N1 human astrocytoma cells.

    PubMed

    Alzeer, Samar; Ellis, Elizabeth M

    2011-05-30

    The role of the aldehyde reductase AKR1A1 in the biosynthesis of gamma-hydroxybutyrate (GHB) has been investigated in cell lines using a specific double stranded siRNA designed to knock down expression of the enzyme. This enzyme, along with the aldo-keto reductase AKR7A2, has been proposed previously to be one of the major succinic semialdehyde reductases in brain. The AKR1A1 siRNA was introduced into the human astrocytoma cell line (1321N1) and AKR1A1 expression was monitored using quantitative reverse-transcriptase PCR and Western blots. Results show an 88% reduction in mRNA levels and a 94% reduction in AKR1A1 protein expression 72 h after transfection with the siRNA. Aldehyde reductase activity was examined in silenced cells by following the aldehyde-dependent conversion of NADPH to NADP at 340 nm. This revealed a 30% decrease in pNBA reductase activity in cell extracts after AKR1A1 silencing. Succinic semialdehyde reductase activity was significantly lower in silenced cells when measured using high concentrations (1mM) of succinic semialdehyde, but not with low concentrations (10 ?M). The effect of silencing on intracellular and extracellular GHB levels was measured using gas chromatography-mass spectrometry. Results show that AKR1A1 has little effect on the production of GHB, indicating that in this cell line alternative enzymes such as the AKR7A2 are likely to play a more significant role in GHB biosynthesis. PMID:21276435

  5. Downregulation of amyloid precursor protein inhibits neurite outgrowth in vitro

    Microsoft Academic Search

    B. Allinquant; P. Hantraye; P. Mailleux; K. Moya; C. BouiUot; A. Prochiantz

    1995-01-01

    The amyloid precursor protein (APP) is a transmembrane protein expressed in several cell types. In the nervous system, APP is expressed by glial and neuronal cells, and several lines of evidence suggest that it plays a role in normal and pathological phenomena. To address the question of the actual function of APP in normal developing neurons, we un- dertook a

  6. Hydroxyapatite formation from a hydrated calcium monohydrogen phosphate precursor

    Microsoft Academic Search

    Marion D. Francis; Ned C. Webb

    1970-01-01

    Hydrated calcium monohydrogen phosphate is proposed as the logical precursor in the formation of hydroxyapatite and a unifying theory for the formation of low calcium, or defect apatites, is presented. Structural relationships between calcium monohydrogen phosphate dihydrate and hydroxyapatite indicate that either material can provide the atomic arrangment for the epitaxial growth of one on the other. The formation of

  7. Thermal properties of fluoride glasses and their gel precursors

    Microsoft Academic Search

    P. Melnikov; R. Rolim; A. Delben; J. R. Delben; A. C. Souza; A. E. Job

    2004-01-01

    Xerogels were prepared from zirconium, barium, aluminum, lanthanum and lithium acetates, corresponding to a Li containing ZBLA composition. The study of their thermal properties (DSC, TG\\/DTG, FT-IR) showed that they might be used as chemically stable precursors in the preparation of fluoride glasses. Hydrofluoric acid in solution was chosen as a mild fluorinating agent. This newly proposed technique of fluorinating

  8. 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...

  9. 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,...

  10. SURROGATE PARAMETERS FOR MONITORING ORGANIC MATTER AND THM PRECURSORS

    EPA Science Inventory

    UV absorbance at 254 nm is a good surrogate parameter for estimating the raw water concentrations of organic carbon (NPTOC--nonpurgeable total organic carbon) and THM precursors (TTHMFP--total trihalomethane formation potential). UV absorbance can be used to estimate the NPTOC an...

  11. Homogeneous precipitation of alumina precursors via enzymatic decomposition of urea

    Microsoft Academic Search

    Hidero Unuma; Shinichi Kato; Toshitaka Ota; Minoru Takahashi

    1998-01-01

    A modified homogeneous precipitation technique involving enzymatic decomposition of urea was proposed and was applied to the synthesis of alumina precursors. Spherical aluminum hydroxide aggregates were prepared at 298 K from aqueous solutions containing aluminum sulfate, urea and urease. In contrast to the conventional technique involving thermally induced decomposition of urea, the resultant aggregates were amorphous with no trace of

  12. Transportation Center Seminar........ "The Panama Canal as Precursor"

    E-print Network

    Bustamante, Fabián E.

    Transportation Center Seminar........ "The Panama Canal as Precursor" Aaron J. Gellman Professor Committee Member, Panama Canal Authority Thursday ­May 24, 2012 4:00 - 5:00 pm Refreshments available at 3 Gellman will provide an overview of the Panama Canal Expansion Project. He will also discuss various

  13. Physiological benefits as precursors of sociality: why banded geckos band

    E-print Network

    Espinoza, Robert E.

    Physiological benefits as precursors of sociality: why banded geckos band JENNIFER R. LANCASTER. Several species of nocturnal geckos form diurnal aggregations; however, little is known about the benefits-dwelling western banded gecko, Coleonyx variegatus. We found that banded geckos benefit from aggregation

  14. 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...

  15. 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.

  16. 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...

  17. 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.

  18. Introduction In many vertebrate cell lineages, precursor cells divide a

    E-print Network

    Richardson, William D.

    been studying the stopping mechanisms in the oligodendrocyte cell lineage in the rodent optic nerve. Oligodendrocyte precursor cells (OPCs) migrate from the brain into the developing rat optic nerve before birth differentiate into oligodendrocytes (Temple and Raff, 1986), which then myelinate the axons in the nerve

  19. The oligodendrocyte precursor cell in health and disease

    Microsoft Academic Search

    Joel M Levine; Richard Reynolds; James W Fawcett

    2001-01-01

    Adult oligodendrocyte precursor cells (OPCs) make up around 5–8% of the glial cell population in the CNS. Their function in the undamaged CNS is largely unknown, but their processes are in contact with nodes of Ranvier and synapses, suggesting a regulatory role at these structures. The cells divide slowly, and constitute ?70% of cells labelled following a pulse injection of

  20. 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.

  1. 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.

  2. Precursors of geomagnetic storms observed by the muon detector network

    Microsoft Academic Search

    Kazuoki Munakata; John W. Bieber; Shin-ichi Yasue; Chihiro Kato; Morikazu Koyama; Shigenobu Akahane; Kazuhiko Fujimoto; Zenjiro Fujii; John E. Humble; Marcus L. Duldig

    2000-01-01

    We report the first systematic survey of cosmic ray precursors of geomagnetic storms. Our data set comprises the 14 ``major'' geomagnetic storms (peak Kp>=8-) identified by Gosling et al. [1990] together with 25 large storms (peak Kp>=7-) observed from 1992 through 1998. After eliminating events for which the muon detector network had poor coverage of the sunward interplanetary magnetic field

  3. Supercritical antisolvent precipitation of nanoparticles of a zinc oxide precursor

    Microsoft Academic Search

    E Reverchon; G Della Porta; D Sannino; P Ciambelli

    1999-01-01

    Supercritical antisolvent (SAS) precipitation has been applied to the production of zinc acetate with the aim of evaluating the applicability of this new process to the production of controlled size nanoparticles of catalyst precursors. SAS process is based on the large volumetric expansion of the liquid solvent induced by the fast diffusion of the antisolvent inside the liquid phase. The

  4. 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.

  5. Hypersensitivity to seizures in ?-amyloid precursor protein deficient mice

    Microsoft Academic Search

    Joachim P. Steinbach; Ulrike Müller; Marcel Leist; Zhi-Wei Li; Pierluigi Nicotera; Adriano Aguzzi

    1998-01-01

    Secreted forms of the ?-amyloid precursor protein (?-APP) have neuroprotective properties in vitro and may be involved in the containment of neuronal excitation. To test whether loss of secreted forms of ?-APP (sAPPs) may enhance excitotoxic responses, we injected mice homozygous for a targeted mutation of the ?-APP gene (?-APP?\\/?) intraperitoneally with kainic acid. We found that in these mice,

  6. 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.

  7. Validation of aggregate delayed neutron spectra calculated from precursor data

    SciTech Connect

    Brady, M. C.; England, T. R. [Oak Ridge National Lab., TN (USA); ,

    1989-01-01

    An extensive reference library of delayed neutron data has been compiled which contains fission yields and branchings, delayed neutron emission probabilities, and spectra for 271 precursors. These data have been used to calculate the aggregate behavior of delayed neutrons following a fission event in 43 fissioning systems. Least-squares techniques were used to produce fitted decay constants and abundances in the conventional six-group formalism from these calculated activity curves. A consistent set of six-group spectra have also been calculated for each of the fissioning systems. Recent measurements at the University of Lowell have produced measured energy spectra for delayed neutrons following the thermal fission (T) of {sup 235}U and {sup 239}Pu, and the fast fission (F) of {sup 238}U. These measured spectra provide data that may be used to validate the precursor data base and the fitted six-group data. This summary presents results of this validation effort. Both the individual precursor data and the six-group data have been used to calculate aggregate equilibrium spectra for {sup 235}U(T), {sup 238}U(F), and {sup 239}Pu(T) via summation techniques. The important precursors in each case are identified, and the status of their data reviewed. 8 refs., 3 figs., 3 tabs.

  8. Apoptotic Osteocytes Regulate Osteoclast Precursor Recruitment and Differentiation In Vitro

    E-print Network

    You, Lidan

    Apoptotic Osteocytes Regulate Osteoclast Precursor Recruitment and Differentiation In Vitro Saja A, Toronto, ON, Canada ABSTRACT Fatigue loading causes a spatial distribution of osteocyte apoptosis co-localized with bone resorption spaces peaking around microdamage sites. Since osteocytes have been shown to regulate

  9. Endogenous Nkx2.2+ oligodendrocyte precursor cells fail

    E-print Network

    Harkema, Susan

    cycling cells with the 0014-4886/$ - see front matter D 2004 Elsevier Inc. All rights reserved. doi:10Endogenous Nkx2.2+ /Olig2+ oligodendrocyte precursor cells fail to remyelinate the demyelinated of Utah, Salt Lake City, UT 84132, USA e Laboratory of Neurosciences, National Institute on Aging

  10. Compatibility of Payload Equipment for Monitoring of the Seismoionospheric Precursors

    Microsoft Academic Search

    Yu. Ya. Ruzhin; A. Kh. Depueva; V. Stefan

    1996-01-01

    The earthquake prediction including precursors appearance and their detection on the Earth's surface and at ionospheric altitudes is a matter of high interest.^2 Present warning systems are based on ground-based monitoring data. Satellite monitoring represents, due to some well known advantages (global scale, continuous records, etc.) a significant progress in the area. It is shown that by means of one

  11. X Ray Precursors in SGRs: Precessing Gamma Jet Tails

    E-print Network

    Daniele Fargion

    2001-05-18

    Weak isolated X-ray precursor events before the main Gamma Ray Burst, GRB, and also rare Soft Gamma Repeaters, SGR, events are in complete disagreement with any Fireball, or Magnetar, one-shoot explosive scenarios. Fireball model in last two years has been deeply modified into a fountain beamed Jet exploding and interacting on external shells to explain GRB fine time structure. On the contrary earlier we proposed a unified scenario for both GRBs-SGRs where a precessing Gamma Jet (of different intensity) and its geometrical beaming is the source of both GRB and SGRs wide morphology. GRBs are peaked SNs Jet spinning and precessing observed along the thin Jet axis. Their mysterious weak X precursors bursts, corresponding to non-negligible energy powers, up to million Supernova ones for GRB, are gamma Jet tails beamed off-axis, observed at X-Ray tails. They are rare, about (3-6)% of all GRBs, but not unique at all. Comparable brief X-ray precursor flashes occurred in rarest and most detailed SGRs events as the 27 and the 29 August 1998 event from SGR 1900+14. The same source has been in very power-full activity on recent 18 April 2001 once again preceded by X-Ray precursors. These events are inconsistent with any Fireball or Magnetar-Mini-Fireball models. We interpret them naturally as earlier marginal blazing of outlying X conical precessing Jet, an off-axis tails surrounding a narrower gamma precessing Jet. Only when the light-house Jet is in on-axis blazing mode toward the Earth we observe the harder power-full SGR event. We predict such a rich X-Ray precursor signals (more numerous then gamma ones) during Soft Gamma Repeater peak activities; they should be abundant and within detection threshold by a permanent monitoring SGRs by Beppo-Sax WFC or Chandra X ray satellites while at peak activity.

  12. Increased Prevalence of Precursor Lesions in Familial Pancreatic Cancer Patients

    PubMed Central

    Shi, Chanjuan; Klein, Alison P; Goggins, Michael; Maitra, Anirban; Canto, Marcia; Ali, Syed; Schulick, Richard; Palmisano, Emily; Hruban, Ralph H

    2009-01-01

    Purpose Histologic findings in 51 pancreata resected from patients with a strong family history of pancreatic cancer were compared to the findings in 40 pancreata resected from patients with sporadic pancreatic cancer. None of the patients in the familial group had a known inherited syndrome, other than familial pancreatic cancer. Experimental Design Precursor lesions, including pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasm (IPMN) and incipient IPMN, were quantified. Invasive cancers were classified using established histologic criteria. Results The individual precursor lesions identified in both groups were histologically similar. Precursor lesions were more common in the familial cases than in the sporadic cases. The Relative Rate of PanINs per cm2 was 2.75 fold higher (95% CI 2.05-3.70, adjusted for age) in familial compared to sporadic cases. PanIN-3 lesions were more common in familial versus sporadic pancreatic cancer patients (Relative Rate 4.20; 95%CI 2.22-7.93 adjusted for age). High-grade incipient IPMNs were only observed in the familial cases. Nine (18%) of the 51 familial pancreatic cancers and 4 (10%) of the 40 sporadic cancers arose in association with an IPMN. No significant differences were found in the types of invasive cancers. Conclusions Non-invasive precursor lesions are more common in patients with a strong family history of pancreatic cancer than in patients with sporadic disease, and precursor lesions are of a higher grade in patients with a strong family history of pancreatic cancer. These findings can form a basis for the design of screening tests for the early detection of pancreatic neoplasia. PMID:19996207

  13. 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.

  14. 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.

  15. Hormonal effects on proliferation of adipocyte precursor cells isolated from chicken enbryos

    E-print Network

    Wu, Ying-Jen

    1994-01-01

    Influence of glucagon (GLU), insulin (IN), growth hormone (GH) , and triiodothyronine (T3) on proliferation of chicken adipocyte precursor cells was examined. Adipocyte precursor cells were isolated from subcutaneous and f emoral adipose depots from...

  16. 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.

  17. Rapid solid-state precursor synthesis of materials.

    PubMed

    Wiley, J B; Kaner, R B

    1992-02-28

    Precursor reactions based on metathetical (exchange) pathways have been found to be an effective synthetic route for the preparation of a large number of materials. These solid-solid reactions are extremely rapid (typically less than 1 second) and often can be initiated at or near room temperature. They are potentially useful for controlling product particle size and for preparing highquality cationic or anionic solid solutions. The frequently self-propagating and sometimes explosive behavior exhibited by these reactions can be attributed to the large amount of heat they release. As a consequence, thermodynamic considerations can be used to help select the best set of precursors as judged from reaction enthalpies. The factors that influence these reactions are illustrated by a discussion of MoS(2), ZrN, MoSi(2), and GaAs, examples of the many compounds accessible by this synthetic route. PMID:17817784

  18. An active precursor in assembly of yeast nuclear ribonuclease P.

    PubMed Central

    Srisawat, Chatchawan; Houser-Scott, Felicia; Bertrand, Edouard; Xiao, Shaohua; Singer, Robert H; Engelke, David R

    2002-01-01

    The RNA-protein subunit assembly of nuclear RNase P was investigated by specific isolation and characterization of the precursor and mature forms of RNase P using an RNA affinity ligand. Pre-RNase P was as active in pre-tRNA cleavage as mature RNase P, although it contained only seven of the nine proteins found in mature RNase P. Pop3p and Rpr2p were not required for maturation of the RPR1 RNA subunit and virtually absent from pre-RNase P, implying that they are dispensable for pre-tRNA substrate recognition and cleavage. The RNase P subunit assembly is likely to occur in the nucleolus, where both precursor and mature forms of RNase P RNA are primarily localized. The results provide insight into assembly of nuclear RNase P, and suggest pre-tRNA substrate recognition is largely determined by the RNA subunit. PMID:12403471

  19. Glycerol, an underestimated flavor precursor in the Maillard reaction.

    PubMed

    Smarrito-Menozzi, Candice; Matthey-Doret, Walter; Devaud-Goumoens, Stéphanie; Viton, Florian

    2013-10-30

    The objective of the present work was to investigate in depth the role of glycerol in Maillard reactions and its potential to act as an active flavor precursor. Reactions using isotopically labeled compounds (various reducing sugars, proline, and glycerol) unambiguously demonstrated that, in addition to its role of solvent, glycerol actively contributes to the formation of proline-specific compounds in Maillard model systems. Additionally, rhamnose and fucose/proline/glycerol systems generated the 2-propionyl-1(3),4,5,6-tetrahydropyridines, known for their roasty, popcorn aroma. Their formation from such systems is unprecedented. The results presented here have direct implications for flavor generation during thermal processing of foods containing glycerol, which is a ubiquitous food ingredient and an underestimated flavor precursor. PMID:23373461

  20. 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

  1. 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 ?V 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. .

  2. 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

  3. Minimal Contribution of Marrow-Derived Endothelial Precursors to Tumor Vasculature1

    Microsoft Academic Search

    Bruno Larrivee; Kyle Niessen; Ingrid Pollet; Stephane Y. Corbel; Michael Long; Fabio M. Rossi; Peggy L. Olive; Aly Karsan

    2005-01-01

    During embryogenesis, vascular and hemopoietic cells originate from a common precursor, the hemangioblast. Recent evidence suggests the existence of endothelial precursors in adult bone marrow cells, but it is unclear whether those precursors have a role in tumor neovascularization. In this report, we demonstrate that murine bone marrow contains endothelial progenitors, which arise from a cell with self-renewing capacity, and

  4. VO2 films with strong semiconductor to metal phase transition prepared by the precursor oxidation process

    E-print Network

    Luryi, Serge

    VO2 films with strong semiconductor to metal phase transition prepared by the precursor oxidation, the precursor oxidation process, for making VO2 films with strong semiconductor-to-metal phase transition. Sputter-deposited metal precursor V films were oxidized in situ in the deposition chamber for 2.5­7 h

  5. 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…

  6. Precursors of morality in the use of the symbols ``good" and ``bad" in two bonobos (Pan

    E-print Network

    Champagne, Frances A.

    Precursors of morality in the use of the symbols ``good" and ``bad" in two bonobos (Pan paniscus Columbia University, New York, NY 10027, United States Abstract Morality is a concept that is based of moral precursors. These findings support recent research that has found moral precursors in several

  7. Clonal identification of multipotent precursors from adult mouse pancreas that generate neural and pancreatic lineages

    Microsoft Academic Search

    Simon R Smukler; Timothy J Kieffer; Grigori Enikolopov; Zeenat Asghar; Michael B Wheeler; Gregory Korbutt; Derek van der Kooy; Raewyn M Seaberg

    2004-01-01

    The clonal isolation of putative adult pancreatic precursors has been an elusive goal of researchers seeking to develop cell replacement strategies for diabetes. We report the clonal identification of multipotent precursor cells from the adult mouse pancreas. The application of a serum-free, colony-forming assay to pancreatic cells enabled the identification of precursors from pancreatic islet and ductal populations. These cells

  8. Characterizing human pancreatic cancer precursor using quantitative tissue optical spectroscopy

    PubMed Central

    Lee, Seung Yup; Lloyd, William R.; Chandra, Malavika; Wilson, Robert H.; McKenna, Barbara; Simeone, Diane; Scheiman, James; Mycek, Mary-Ann

    2013-01-01

    In a pilot study, multimodal optical spectroscopy coupled with quantitative tissue-optics models distinguished intraductal papillary mucinous neoplasm (IPMN), a common precursor to pancreatic cancer, from normal tissues in freshly excised human pancreas. A photon-tissue interaction (PTI) model extracted parameters associated with cellular nuclear size and refractive index (from reflectance spectra) and extracellular collagen content (from fluorescence spectra). The results suggest that tissue optical spectroscopy has the potential to characterize pre-cancerous neoplasms in human pancreatic tissues. PMID:24409383

  9. 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.

  10. A common precursor for primitive erythropoiesis and definitive haematopoiesis

    Microsoft Academic Search

    Marion Kennedy; Meri Firpo; Kyunghee Choi; Charles Wall; Scott Robertson; Neil Kabrun; Gordon Keller

    1997-01-01

    The generation of blood cells, haematopoiesis, in the mouse embryo begins with the development of primitive nucleated erythroid cells in the yolk sac followed by the appearance of precursors for multiple definitive haematopoietic lineages1-4. The later developing lineages arise from multipotential stem cells5,6, but the relationship of primitive erythroid cells to these other haematopoietic populations is unknown. Using an in

  11. Evaluation of precursors for chemical vapor deposition of ruthenium

    Microsoft Academic Search

    K. C Smith; Y.-M Sun; N. R Mettlach; R. L Hance; J. M White

    2000-01-01

    Several commercially available organometallic precursors have been evaluated for metallorganic chemical vapor deposition (MOCVD) of pure ruthenium films. Of these, only a dimer, [RuC5H5(CO)2]2, proved suitable for CVD. On patterned Si3N4 and flat barium strontium titanate (BST), pure, conductive, conformal ruthenium films were grown from this dimer when oxygen was used as a reaction gas. Without oxygen, significant amounts of

  12. Strain-stabilized precursor clusters in potassium thiocyanate

    Microsoft Academic Search

    O. Blaschko; W. Schranz; M. Fally; G. Krexner; Z. Lodziana

    1998-01-01

    We present refined diffuse neutron scattering measurements performed in the long-range-ordered phase of potassium thiocyanate (Tprecursor to the order-disorder phase transition. The diffuse intensity increases when approaching Tc from below, whereas the width remains constant in the

  13. The 2004 Parkfield earthquake: Test of the electromagnetic precursor hypothesis

    Microsoft Academic Search

    Stephen K. Park; William Dalrymple; Jimmy C. Larsen

    2007-01-01

    A controversy has existed for 30 years concerning the possibility of earthquake prediction using electromagnetic precursors. Long-term electromagnetic monitoring prior to, during, and after the M6.0 earthquake at Parkfield, California, on 28 September 2004 now provides a definitive test of this hypothesis. During the earthquake our instruments recorded clearly documented electrical signals from an earthquake: impulsive changes of up to

  14. Synthesis of Monodispersed Magnetite Particles From Different Organometallic Precursors

    Microsoft Academic Search

    A. G. Roca; M. P. Morales; C. J. Serna

    2006-01-01

    Magnetite (Fe3O4) nanoparticles with very narrow particle size distribution can be obtained by decomposition of an organometallic compound in the presence of oleic acid. It has been shown that the carboxylic acid catalyzes the reaction leading to decreased decomposition temperatures and, consequently, as the surfactant concentration increases, smaller particles are formed. Precursors such as Fe(CO)5, iron acetylacetonate, and iron-oleate complexes,

  15. 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. .

  16. Interpollutant emission trading of ozone precursors in southeast Texas

    Microsoft Academic Search

    Linlin Wang; David Allen; Elena McDonald-Buller

    2009-01-01

    Interpollutant trading (IPT) allows for trades among emissions of different compounds that contribute to ambient concentrations\\u000a of the same pollutant. Shortages of single pollutant offsets have motivated the consideration of interpollutant offsets for\\u000a ozone precursors on a case-by-case basis in California, but IPT has been approached with caution because of the difficulties\\u000a in assessing the adequacy and uncertainty of trading

  17. Synthesis of precursors of histamine peptides found in bee venom 

    E-print Network

    Johnson, Timothy James

    1975-01-01

    J (Member) (Member) August 1975 ABSTRACT Synthesis of Precursors of Histamine Peptides found in Bee Venom (Aug. 1975) Timothy J. Johnson, B. S. , Texas AIM University Chairman of Advisory Committee: Dr. Rod O' Connor Two unique peptides, each.... Rod O' Connor and Dr. M. L. Peck. My sincere appreciation is expressed' to Dr. A. F. Isbell for his many hours of expert consultation and a, ssistance in this research. I would also like to thank the Chemistry Department for a Teaching...

  18. Precursors, aftershocks, criticality and self-organized criticality

    Microsoft Academic Search

    Y. Huang; H. Saleur; C. G. Sammis; D. Sornette

    1998-01-01

    We present a simple model of earthquakes on a pre-existing hierarchical fault structure. The system self-organizes at large times in a stationary state with a power law Gutenberg-Richter distribution of earthquake sizes. The largest fault carries irregular great earthquakes preceded by precursors developing over long time scales and followed by aftershocks obeying an Omori's law. The cumulative energy released by

  19. Fission-based electric propulsion for interstellar precursor missions

    Microsoft Academic Search

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

    2000-01-01

    This paper reviews the technology options for a fission-based electric propulsion system for interstellar precursor missions. To achieve a total DeltaV 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

  20. Fission-Based Electric Propulsion for Interstellar Precursor Missions

    Microsoft Academic Search

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

    1999-01-01

    This paper reviews the technology options for a fission-based electric propulsion system for interstellar precursor missions. To achieve a total ÎV 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)

  1. Multicomponent Assembly of Proposed DNA Precursors in Water

    PubMed Central

    2012-01-01

    We propose a novel pathway for the prebiotic synthesis of 2?-deoxynucleotides. Consideration of the constitutional chemical relationships between glycolaldehyde and ?-mercapto-acetaldehyde, and the corresponding proteinogenic amino acids, serine and cysteine, led us to explore the consequences of the corresponding sulfur substitution for our previously proposed pathways leading to the canonical ribonucleotides. We demonstrate that just as 2-aminooxazole–an important prebiotic ribonucleotide precursor–is readily formed from glycolaldehyde and cyanamide, so is 2-aminothiazole formed from ?-mercapto-acetaldehyde and cyanamide in water at neutral pH. Indeed, both the oxazole and the thiazole can be formed together in a one-pot reaction, and can be co-purified by crystallization or sublimation. We then show that 2-aminothiazole can take part in a 3-component carbon–carbon bond-forming reaction in water that leads to the diastereoselective synthesis of masked 2?-thiosugars regiospecifically tethered to purine precursors, which would lead to 2?-deoxynucleotides upon desulfurization. The possibility of an abiotic route to the 2?-deoxynucleotides provides a new perspective on the evolutionary origins of DNA. We also show that 2-aminothiazole is able to sequester, through reversible aminal formation, the important nucleotide precursors glycolaldehyde and glyceraldehyde in a stable, crystalline form. PMID:22839703

  2. Multicomponent assembly of proposed DNA precursors in water.

    PubMed

    Powner, Matthew W; Zheng, Shao-Liang; Szostak, Jack W

    2012-08-22

    We propose a novel pathway for the prebiotic synthesis of 2'-deoxynucleotides. Consideration of the constitutional chemical relationships between glycolaldehyde and ?-mercapto-acetaldehyde, and the corresponding proteinogenic amino acids, serine and cysteine, led us to explore the consequences of the corresponding sulfur substitution for our previously proposed pathways leading to the canonical ribonucleotides. We demonstrate that just as 2-aminooxazole-an important prebiotic ribonucleotide precursor-is readily formed from glycolaldehyde and cyanamide, so is 2-aminothiazole formed from ?-mercapto-acetaldehyde and cyanamide in water at neutral pH. Indeed, both the oxazole and the thiazole can be formed together in a one-pot reaction, and can be co-purified by crystallization or sublimation. We then show that 2-aminothiazole can take part in a 3-component carbon-carbon bond-forming reaction in water that leads to the diastereoselective synthesis of masked 2'-thiosugars regiospecifically tethered to purine precursors, which would lead to 2'-deoxynucleotides upon desulfurization. The possibility of an abiotic route to the 2'-deoxynucleotides provides a new perspective on the evolutionary origins of DNA. We also show that 2-aminothiazole is able to sequester, through reversible aminal formation, the important nucleotide precursors glycolaldehyde and glyceraldehyde in a stable, crystalline form. PMID:22839703

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

    SciTech Connect

    Schulz, D.L.; Curtis, C.J.; Flitton, R.A.; Wiesner, H.; Keane, J.; Matson, R.J.; Parilla, P.A.; Noufi, R.; Ginley, D.S. [Center for Photovoltaic and Electronic Materials and Center for Basic Sciences, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401-3393 (United States)

    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{endash}V characterization of these CIGS solar cells showed these devices are limited by a large series resistance. {copyright} {ital 1997 American Institute of Physics.}

  4. Precursor transformation method for damage detection in structures

    NASA Astrophysics Data System (ADS)

    Mehrabi, Armin B.; Tabatabai, Habib; Lotfi, Hamid R.

    1998-06-01

    In this paper, a new concept for damage detection and long- term health monitoring of structures is presented. The Precursor Transformation Method (PTM) is based on determining the causes (precursors) of change in the measured state of the structure under non-variable loading conditions (e.g. dead loads in bridges). The PTM concept addresses the inability of the current structural monitoring methods to discriminate, in structural behavior terms, the meaning of voluminous measured sensor data on a timely and cost effective basis. This method offers advantages in sensitivity and cost efficiency when compared to conventional vibration-based or parameter estimation methods. PTM was developed as part of a research project sponsored by the Federal Highway Administration on bridge stay cable condition assessment. Measured changes in the state of a structure (displacements, strains, internal forces) can be related to precursors through a transformation matrix. This matrix is formed by determining the patterns of change in the state of structure associated with externally imposed strains (temperatures) or displacements representing possible damage scenarios. A finite element model of the undamaged structure is used to calculate these patterns. The use of an undamaged model of the structure in determining damage patterns simplifies the calculation process significantly, while introducing some approximation in results. Theoretical derivations and special case studies indicate that these approximations are limited to second order effects, and in many cases well within measurement and calculation accuracies. Examples using simulated damages on two truss structures and a cable-stayed bridge are also presented.

  5. Prolactin Stimulates Precursor Cells in the Adult Mouse Hippocampus

    PubMed Central

    Walker, Tara L.; Vukovic, Jana; Koudijs, Margaretha M.; Blackmore, Daniel G.; Mackay, Eirinn W.; Sykes, Alex M.; Overall, Rupert W.; Hamlin, Adam S.; Bartlett, Perry F.

    2012-01-01

    In the search for ways to combat degenerative neurological disorders, neurogenesis-stimulating factors are proving to be a promising area of research. In this study, we show that the hormonal factor prolactin (PRL) can activate a pool of latent precursor cells in the adult mouse hippocampus. Using an in vitro neurosphere assay, we found that the addition of exogenous PRL to primary adult hippocampal cells resulted in an approximate 50% increase in neurosphere number. In addition, direct infusion of PRL into the adult dentate gyrus also resulted in a significant increase in neurosphere number. Together these data indicate that exogenous PRL can increase hippocampal precursor numbers both in vitro and in vivo. Conversely, PRL null mice showed a significant reduction (approximately 80%) in the number of hippocampal-derived neurospheres. Interestingly, no deficit in precursor proliferation was observed in vivo, indicating that in this situation other niche factors can compensate for a loss in PRL. The PRL loss resulted in learning and memory deficits in the PRL null mice, as indicated by significant deficits in the standard behavioral tests requiring input from the hippocampus. This behavioral deficit was rescued by direct infusion of recombinant PRL into the hippocampus, indicating that a lack of PRL in the adult mouse hippocampus can be correlated with impaired learning and memory. PMID:22973440

  6. Pancreatic neurogenin 3-expressing cells are unipotent islet precursors

    PubMed Central

    Desgraz, Renaud; Herrera, Pedro L.

    2009-01-01

    Summary Pancreatic islet endocrine cells arise during development from precursors expressing neurogenin 3 (Ngn3). As a population, Ngn3+ cells produce all islet cell types, but the potential of individual Ngn3+ cells, an issue central to organogenesis in general and to in vitro differentiation towards cell-based therapies, has not been addressed. We performed in vivo clonal analyses in mice to study the proliferation and differentiation of very large numbers of single Ngn3+ cells using MADM, a genetic system in which a Cre-dependent chromosomal translocation labels, at extremely low mosaic efficiency, a small number of Ngn3+ cells. We scored large numbers of progeny arising from single Ngn3+ cells. In newborns, labeled islets frequently contained just a single tagged endocrine cell, indicating for the first time that each Ngn3+ cell is the precursor of a single endocrine cell. In adults, small clusters of two to three Ngn3+ progeny were detected, but all expressed the same hormone, indicating a low rate of replication from birth to adult stages. We propose a model whereby Ngn3+ cells are monotypic (i.e. unipotent) precursors, and use this paradigm to refocus ideas on how cell number and type must be regulated in building complete islets of Langerhans. PMID:19793886

  7. 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. [Sandia National Labs., Albuquerque, NM (United States). Advanced Materials Lab.

    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.

  8. 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

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

    PubMed

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

    2013-05-01

    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

  10. 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

  11. 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.

  12. 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.

  13. 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. (Lakewood, CO); Miedaner, Alexander (Boulder, CO); van Hest, Marinus Franciscus Antonius Maria (Lakewood, CO); Ginley, David S. (Evergreen, CO); Leisch, Jennifer (Denver, CO); Taylor, Matthew (West Simsbury, CT); Stanbery, Billy J. (Austin, TX)

    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.

  14. Nicotiana benthamiana as a Production Platform for Artemisinin Precursors

    PubMed Central

    van Herpen, Teun W. J. M.; Cankar, Katarina; Nogueira, Marilise; Bosch, Dirk; Bouwmeester, Harro J.; Beekwilder, Jules

    2010-01-01

    Background Production of pharmaceuticals in plants provides an alternative for chemical synthesis, fermentation or natural sources. Nicotiana benthamiana is deployed at commercial scale for production of therapeutic proteins. Here the potential of this plant is explored for rapid production of precursors of artemisinin, a sesquiterpenoid compound that is used for malaria treatment. Methodology/Principal Findings Biosynthetic genes leading to artemisinic acid, a precursor of artemisinin, were combined and expressed in N. benthamiana by agro-infiltration. The first committed precursor of artemisinin, amorpha-4,11-diene, was produced upon infiltration of a construct containing amorpha-4,11-diene synthase, accompanied by 3-hydroxy-3-methylglutaryl-CoA reductase and farnesyl diphosphate synthase. Amorpha-4,11-diene was detected both in extracts and in the headspace of the N. benthamiana leaves. When the amorphadiene oxidase CYP71AV1 was co-infiltrated with the amorphadiene-synthesizing construct, the amorpha-4,11-diene levels strongly decreased, suggesting it was oxidized. Surprisingly, no anticipated oxidation products, such as artemisinic acid, were detected upon GC-MS analysis. However, analysis of leaf extracts with a non-targeted metabolomics approach, using LC-QTOF-MS, revealed the presence of another compound, which was identified as artemisinic acid-12-?-diglucoside. This compound accumulated to 39.5 mg.kg?1 fwt. Apparently the product of the heterologous pathway that was introduced, artemisinic acid, is further metabolized efficiently by glycosyl transferases that are endogenous to N. benthamiana. Conclusion/Significance This work shows that agroinfiltration of N. bentamiana can be used as a model to study the production of sesquiterpenoid pharmaceutical compounds. The interaction between the ectopically introduced pathway and the endogenous metabolism of the plant is discussed. PMID:21151979

  15. 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. [Blackett Laboratory, Imperial College London SW7 2BW (United Kingdom)] [Blackett Laboratory, Imperial College London SW7 2BW (United Kingdom); Williams, R. J. R. [Atomic Weapons Establishment, Aldermaston RG7 4PR (United Kingdom)] [Atomic Weapons Establishment, Aldermaston RG7 4PR (United Kingdom); Blesener, K.; Atoyan, L.; Cahill, A.; Hoyt, C.; Potter, W. [Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States)] [Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States); 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.

  16. 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.

  17. Enzymatic synthesis of chiral organophosphothioates from prochiral precursors.

    PubMed

    Li, Wen-Shan; Li, Yingchun; Hill, Craig M; Lum, Karin T; Raushel, Frank M

    2002-04-10

    The phosphotriesterase from Pseudomonas diminuta has been shown to selectively cleave the pro-R p-nitrophenolate substituent from bis-p-nitrophenyl alkyl phosphothioate esters. When the alkyl substituent is methyl, ethyl, or isopropyl the enantiomeric excess of the product is >/=99%. Manipulation of the active site through mutagenesis has enabled the preparation of protein variants that preferentially hydrolyze the pro-S substituent of the target substrates. This methodology thus permits the preparation of chiral products from prochiral precursors. PMID:11929226

  18. Interactions of Omeprazole and Precursors with beta Cyclodextrin Host Molecules

    Microsoft Academic Search

    Susana S. Braga; Paulo Ribeiro-Claro; Martyn Pillinger; Isabel S. Gonçalves; Ana C. Fernandes; Florbela Pereira; Carlos C. Romão; Pedro Brito Correia; José J. C. Teixeira-Dias

    2003-01-01

    ß-Cyclodextrin (ß-CD) was mixed with omeprazoleand some of its precursors in aqueous or water\\/ethanol solutions, and theresulting crystalline products have been characterized by elemental analysis,thermogravimetry, powder X-ray diffraction (XRD), FTIR and 13C CP MAS NMRspectroscopy. In the case of2-chloromethyl-4-methoxy-3,5-dimethylpyridine...HCl, itwas found that the solid product always consisted of pure ß-CD hydrate. On the other hand, a 2 : 1(host-to-guest) inclusion

  19. 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.

  20. 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

  1. The wireless networking system of Earthquake precursor mobile field observation

    NASA Astrophysics Data System (ADS)

    Wang, C.; Teng, Y.; Wang, X.; Fan, X.; Wang, X.

    2012-12-01

    The mobile field observation network could be real-time, reliably record and transmit large amounts of data, strengthen the physical signal observations in specific regions and specific period, it can improve the monitoring capacity and abnormal tracking capability. According to the features of scatter everywhere, a large number of current earthquake precursor observation measuring points, networking technology is based on wireless broadband accessing McWILL system, the communication system of earthquake precursor mobile field observation would real-time, reliably transmit large amounts of data to the monitoring center from measuring points through the connection about equipment and wireless accessing system, broadband wireless access system and precursor mobile observation management center system, thereby implementing remote instrument monitoring and data transmition. At present, the earthquake precursor field mobile observation network technology has been applied to fluxgate magnetometer array geomagnetic observations of Tianzhu, Xichang,and Xinjiang, it can be real-time monitoring the working status of the observational instruments of large area laid after the last two or three years, large scale field operation. Therefore, it can get geomagnetic field data of the local refinement regions and provide high-quality observational data for impending earthquake tracking forecast. Although, wireless networking technology is very suitable for mobile field observation with the features of simple, flexible networking etc, it also has the phenomenon of packet loss etc when transmitting a large number of observational data due to the wireless relatively weak signal and narrow bandwidth. In view of high sampling rate instruments, this project uses data compression and effectively solves the problem of data transmission packet loss; Control commands, status data and observational data transmission use different priorities and means, which control the packet loss rate within an acceptable range and do not affect real-time observation curve. After field running test and earthquake tracking project applications, the field mobile observation wireless networking system is operate normally, various function have good operability and show good performance, the quality of data transmission meet the system design requirements and play a significant role in practical applications.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Synthesis of carbon nanotubes using natural carbon precursor: Castor oil

    NASA Astrophysics Data System (ADS)

    Raziah, A. Z.; Junizah, A. R.; Saifuddin, N.

    2012-09-01

    Castor oil has long been an article of commerce due to its versatility as it is widely used as a starting material for many industrial chemical products because of its unique structure. In this study, carbon nanotubes has been synthesized by thermal decomposition of castor oil in nitrogen atmosphere at 300-400?C using custom-made microwave processing unit. The precursor material was catalyzed by iron clusters originating from the addition of ferrocene. The morphology and characterization of the CNTs were studied and discussed by transmission electron microscopy (TEM).

  7. Lunar Precursor Robotic Program: A Robotic Focus To The Vision

    NASA Technical Reports Server (NTRS)

    French, Raymond A.; Nall, Mark E.

    2007-01-01

    In April 2006, NASA, with help from the commercial and international communities, began developing a global Lunar Exploration Strategy. These activities resulted in themes that expanded on why we should return to the Moon and objectives that identify what we should do when we get there. NASA used these results to develop a Lunar Architecture designed to achieve the subset of the global Lunar Exploration Strategy objectives that fit within NASA's scope. A component of this architecture is the Lunar Precursor Robotic Program. This Program, anticipated to consist of both lunar orbiters and landers, is intended to meet many of NASA's lunar exploration objectives.

  8. Preparation of Nanostructured Zinc Oxide from Single Source Precursors

    Microsoft Academic Search

    Anil M. Palve; Shivram S. Garje

    2010-01-01

    Nanostructured ZnO was prepared by pyrolysis of single source precursors, ZnCl2(benzsczH)2 and ZnCl2(cinnamsczH)2 (where, benzsczH = benzaldehyde semicarbazone and cinnamsczH = cinnamaldehyde semicarbazone). Powder X-ray diffraction pattern (PXRD) shows formation of hexagonal ZnO. The peak broadening in PXRD and absorption towards blue region in absorption spectra confirms the formation of nanoscale ZnO. The transmission electron microscopy images reveal formation of

  9. Effect of supplementing terpenoid biosynthetic precursors on the accumulation of bilobalide and ginkgolides in Ginkgo biloba cell cultures

    Microsoft Academic Search

    Seung-Mi Kang; Ji-Yun Min; Yong-Duck Kim; Dong-Jin Park; Ha-Na Jung; Chandrakant S. Karigar; Yeong-Lae Ha; Seon-Won Kim; Myung-Suk Choi

    2006-01-01

    The effect of precursor feeding on the production of bilobalide and ginkgolides was studied with suspension cell cultures of Ginkgo biloba. The precursors greatly influenced the productivity of bilobalide and ginkgolides. Precursor supplementation increased the accumulation of both bilobalide and ginkgolides, and with positive effect on cell growth. The GA accumulation by cell cultures was influenced by precursors upstream in

  10. Assembly and architecture of precursor nodes during fission yeast cytokinesis

    PubMed Central

    Laporte, Damien; Coffman, Valerie C.; Lee, I-Ju

    2011-01-01

    The contractile ring is essential for cytokinesis in most fungal and animal cells. In fission yeast, cytokinesis nodes are precursors of the contractile ring and mark the future cleavage site. However, their assembly and architecture have not been well described. We found that nodes are assembled stoichiometrically in a hierarchical order with two modules linked by the positional marker anillin Mid1. Mid1 first recruits Cdc4 and IQGAP Rng2 to form module I. Rng2 subsequently recruits the myosin-II subunits Myo2 and Rlc1. Mid1 then independently recruits the F-BAR protein Cdc15 to form module II. Mid1, Rng2, Cdc4, and Cdc15 are stable node components that accumulate close to the plasma membrane. Both modules recruit the formin Cdc12 to nucleate actin filaments. Myo2 heads point into the cell interior, where they efficiently capture actin filaments to condense nodes into the contractile ring. Collectively, our work characterizing the assembly and architecture of precursor nodes defines important steps and molecular players for contractile ring assembly. PMID:21422229

  11. Over-the-Horizon Anomalous VHF Propagation and Earthquake Precursors

    NASA Astrophysics Data System (ADS)

    Devi, M.; Barbara, A. K.; Ruzhin, Ya. Yu.; Hayakawa, M.

    2012-09-01

    The purpose of this paper is to review current activities for the identification of earthquake (EQ) precursors and their epicentres. Starting with a brief description on the background to approaches using ultra-low (ULF), extremely low (ELF), very low/low (VLF/LF), medium (MF), high (HF), very high frequency (VHF) etc. radio waves for short-term EQ prediction, the paper concentrates on those characteristics of anomalous VHF reception from frequency-modulation (FM) radio transmissions and broadcast television (TV) signals in relation to EQ precursors. The possible ways to identify an impending EQ and its epicentre position as defined and observed by workers from a variety of studies fall within the purview of the paper. In attempts to find pre-EQ energy exchange and coupling processes between the lithosphere and atmosphere, the paper highlights some relevant observations of surface latent heat flux, sonic detection and ranging (SODAR) echograms and LF propagation. Explanations on possible causes leading to such anomalous reception are reviewed with reported results in association with pre-seismic induced modifications to tropospheric and ionospheric parameters.

  12. Labeling of human neural precursor cells using ferromagnetic nanoparticles.

    PubMed

    Focke, Almut; Schwarz, Sigrid; Foerschler, Annette; Scheibe, Johanna; Milosevic, Javorina; Zimmer, Claus; Schwarz, Johannes

    2008-12-01

    Fetal human neural precursor cells (NPCs) are unique with respect to their capacity to proliferate and to preserve their potential to differentiate into neurons and glia. Human mesencephalic neural precursor cells (hmNPCs) provide a source for dopaminergic neurons. Preclinical and clinical research will benefit from reliable in vivo tracking of transplanted cells. Here, we investigate the potency of very small superparamagnetic iron oxide particles (VSOPs) to label hmNPCs, the effect of VSOPs on survival, proliferation, and differentiation of hmNPCs, and the sensitivity of 1.5T magnetic resonance imaging (MRI) to detect labeled cells in living rats following transplantation. When incubated with VSOPs at 1.5 mM, >95% of hmNPCs incorporated VSOPs without detectable impact on cell viability (>90%) or proliferative capacity, as measured by the expression of proliferating cell nuclear antigen (PCNA) and cell cycle distribution. Labeled hmNPCs differentiate into neurons (>30%) and glia with no detectable difference compared to nonlabeled cells. Following transplantation into rat striata, marked paramagnetic signal changes were detected for as long as three months postsurgery using MRI, corresponding to the histologically-identified graft. Our data indicate that hmNPCs can be labeled with VSOPs without impairment of viability, proliferation, or multipotency. Labeled, transplanted cells are detectable in vivo using 1.5T MRI. PMID:19025881

  13. Fabrication of superconducting wire using organometallic precursors and infiltration

    SciTech Connect

    Lee, Y.J.

    1991-01-01

    Organometallic precursors from naphthenic acid and metal nitrates were used for the synthesis of YBCO oxide superconducting compounds. The characteristics of metal naphthenates as organometallic precursors were investigated by IR spectra, viscosity measurements, and infiltration. 123 superconducting compound obtained from 123 naphthenate showed a Tc of 90{degree}K and a rather dense and elongated microstructure. Also, the melting behavior of Ba-cuprates which were used for 123 making was studied. A low-temperature melting process was developed to fabricate silver-sheathed superconducting wire with the powder-in-tube method; flowing argon gas is introduced to the system at 930-945{degree}C to reduce the melting temperature of the 123 compound without silver sheath melting. It resulted in a 90{degree}K Tc superconducting core with dense and locally aligned microstructure. SEM-EDS and XRD analysis, 4-probe resistance and Jc measurements, and carbon-content determinations were carried out to characterize the microstructure, grain alignment, and superconducting properties of the samples.

  14. Preparation of plutonium-bearing ceramics via mechanically activated precursor

    NASA Astrophysics Data System (ADS)

    Chizhevskaya, S. V.; Stefanovsky, S. V.

    2000-07-01

    The problem of excess weapons plutonium disposition is suggested to be solved by means of its incorporation in stable ceramics with high chemical durability and radiation resistivity. The most promising host phases for plutonium as well as uranium and neutron poisons (gadolinium, hafnium) are zirconolite, pyrochlore, zircon, zirconia [1,2], and murataite [3]. Their production requires high temperatures and a fine-grained homogeneous precursor to reach final waste form with high quality and low leachability. Currently various routes to homogeneous products preparation such as sol-gel technology, wet-milling, and grinding in a ball or planetary mill are used. The best result demonstrates sol-gel technology but this route is very complicated. An alternative technology for preparation of ceramic precursors is the treatment of the oxide batch with high mechanical energy [4]. Such a treatment produces combination of mechanical (fine milling with formation of various defects, homogenization) and chemical (split bonds with formation of active centers—free radicals, ion-radicals, etc.) effects resulting in higher reactivity of the activated batch.

  15. Solution Structures of Chemoenzymatically Synthesized Heparin and Its Precursors

    PubMed Central

    Zhang, Zhenqing; McCallum, Scott A.; Xie, Jin; Nieto, Lidia; Corzana, Francisco; Jiménez-Barbero, Jesús; Chen, Miao; Liu, Jian; Linhardt, Robert J.

    2009-01-01

    We report the first chemoenzymatic synthesis of the stable isotope-enriched heparin from a uniformly labeled [13C,15N]N-acetylheparosan (-GlcA(1,4)GlcNAc-) prepared from E. coli K5. Glycosaminoglycan (GAG) precursors and heparin were formed from N-acetylheparosan by the following steps: chemical N-deacetylation and N-sulfonation leading to N-sulfoheparosan (-GlcA(1,4)GlcNS-); enzyme-catalyzed C5-epimerization and 2-O-sulfonation leading to undersulfated heparin (-IdoA2S(1,4)GlcNS-); enzymatic 6-O-sulfonation leading to the heparin backbone (-IdoA2S(1,4)GlcNS6S-); and selective enzymatic 3-O-sulfonation leading to the anticoagulant heparin, containing the GlcNS6S3S residue. Heteronuclear, multidimensional nuclear magnetic resonance spectroscopy was employed to analyze the chemical composition and solution structure of [13C,15N]N-acetylheparosan, precursors, and heparin. Isotopic enrichment was found to provide well-resolved 13C spectra with the high sensitivity required for conformational studies of these biomolecules. Stable isotope-labeled heparin was indistinguishable from heparin derived from animal tissues and is a novel reagent for studying the interaction of heparin with proteins. PMID:18767845

  16. Refractory precursor components in an Allende ferromagnesian chondrule

    NASA Technical Reports Server (NTRS)

    Misawa, Keiji; Fujita, Takashi; Kitamura, Masao; Nakamura, Noboru

    1993-01-01

    Chemical and petrological studies of chondrules revealed that they were formed through melting of pre-existing solid precursor materials, and that one of the refractory lithophile precursors was a high temperature condensate from the nebular gas and related to Ca, Al-rich inclusions (CAIs). Sheng et al. found relict spinel grains with isotopically fractionated Mg in plagioclase-olivine inclusions from CV chondrites and suggested that the major fractionation processes were common to CAIs and chondrules. We have determined the Mg isotopic compositon of five barred olivine chondrules and one coarse-grained rim from the Allende (CV3) meteorite. A reproducibility of instrumental isotope fractionation is plus or minus 2 per thousand per amu. The precision of the Mg-26/Mg-24 data after normalization for mass fractionation can be as good as 0.5 per thousand (2 sigma(mean)). The Mg analytical results are given and indicate that delta Mg-25/Mg-24 and sigma Mg-26 of the chondrules are normal within errors.

  17. 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

  18. Atmospheric perfluorinated acid precursors: chemistry, occurrence, and impacts.

    PubMed

    Young, Cora J; Mabury, Scott A

    2010-01-01

    Perfluorocarboxylic acids (PFCAs) can be found from the hydrolysis of perfluoroacyl fluorides and chlorides, which can be produced in three separate ways in the atmosphere. Alternatively, PFCAs can be formed directly in the gas phase through reaction of perfluoroacyl peroxy radicals or perfluorinated aldehyde hydrates. All five mechanisms have been elucidated using smog chamber techniques. Yields of the PFCAs from this process vary from less than 10% to greater than 100%, depending on the mechanism. The formation of perfluorosulfonic acids in the atmosphere can also occur, though the mechanism has not been entirely elucidated. A large number of compounds have been confirmed as perfluorinated acid precursors, including CFC-replacement compounds, anesthetics, fluorotelomer compounds, and perfluorosulfonamides. Levels of some of these compounds have been measured in the atmosphere, but concentration for the majority have yet to be detected. It is clear that atmospheric oxidation of volatile precursors contributes to the overall burden of PFAs, though the extent to which this occurs is compound and environment dependent and is difficult to assess accurately. PMID:20811862

  19. Formation of BaTiO 3 from Citrate Precursor

    NASA Astrophysics Data System (ADS)

    Rajendran, M.; Rao, M. Subba

    1994-12-01

    On thermal decomposition barium bis(citrato)oxotitanate (IV) citrate heptahydrate produces stoichiometric BaTiO 3 fine powders at about 650°C. Thermal decomposition of the precursor proceeds through three major stages, viz. (i) dehydration, (ii) decomposition of the citrate to form an oxycarbonate intermediate Ba 2Ti 2O 5CO 3, and (iii) decomposition of the intermediate carbonate to form BaTiO 3. Spectroscopic and thermoanalytical techniques are presently employed to characterize the precursor and the intermediates isolated at various stages. As-prepared BaTiO 3 is a mixture of cubic and tetragonal phases. The primary particle size of the powder is on the order of 100 nm, as revealed by the TEM technique. Calcining the powders above 800°C results in the formation of complete tetragonal phase with improved crystallinity. The resultant powders are sinter active to give dense monophasic ceramic compacts having densities in the range 95-99% of the theoretical value. Depending on the processing conditions, the dielectric constant (? r) varies from 1600 to 3000 at 1 kHz, while the dielectric loss, tan ?, ranges from 0.003 to 0.009 at 300 K.

  20. The influence of cholesterol precursor - desmosterol - on artificial lipid membranes.

    PubMed

    H?c-Wydro, Katarzyna; W?der, Karolina; Mach, Marzena; Flasi?ski, Micha?; Wydro, Pawe?

    2015-08-01

    The disorders in cholesterol biosynthesis pathway and various diseases manifest in the accumulation of cholesterol precursors in the human tissues and cellular membranes. In this paper the effect of desmosterol - one of cholesterol precursors - on model lipid membranes was studied. The investigations were performed for binary SM/desmo and POPC/desmo and ternary SM/POPC/desmo monolayers. Moreover, the experiments based on the gradual substitution of cholesterol by desmosterol in SM/POPC/chol=1:1:1 system were done. The obtained results allowed one to conclude that desmosterol is of lower domains promoting and stabilizing properties and packs less tightly with the lipids in monolayers. Moreover, desmosterol probably could replace cholesterol in model membranes, but only at its low proportion in the system (2%), however, at a higher degree of cholesterol substitution a significant decrease of the monolayer stability and packing and alterations in the film morphology were detected. The results collected in this work together with those from previous experiments allowed one to analyze the effect of a double bond in the sterol side chain as well as its position in the ring system on membrane activity of the molecule and to verify Bloch hypothesis. PMID:25960185

  1. Circulating Osteogenic Precursor Cells in Heterotopic Bone Formation

    PubMed Central

    Suda, Robin K.; Billings, Paul C.; Egan, Kevin P.; Kim, Jung-Hoon; McCarrick-Walmsley, Ruth; Glaser, David L.; Porter, David L.; Shore, Eileen M.; Pignolo, Robert J.

    2012-01-01

    Cells with osteogenic potential can be found in a variety of tissues. Here we show that circulating osteogenic precursor (COP) cells, a bone marrow-derived type I collagen+/CD45+ subpopulation of mononuclear adherent cells, are present in early pre-osseous fibroproliferative lesions in patients with fibrodysplasia ossificans progressiva (FOP) and nucleate heterotopic ossification (HO) in a murine in vivo implantation assay. Blood samples from FOP patients with active episodes of HO contain significantly higher numbers of clonally-derived COP cell colonies than patients with stable disease or unaffected individuals. The highest level of COP cells was found in a patient just prior to the clinical onset of an HO exacerbation. Our studies show that even COP cells derived from an unaffected individual can contribute to HO in genetically susceptible host tissue. The possibility that circulating, hematopoietic-derived cells with osteogenic potential can seed inflammatory sites has tremendous implications and, to our knowledge, represents the first example of their involvement in clinical HO. Thus, bone formation is not limited to cells of the mesenchymal lineage, and circulating cells of hematopoietic origin can also serve as osteogenic precursors at remote sites of tissue inflammation. PMID:19522009

  2. MAGNETIC AND DENSITY SPIKES IN COSMIC-RAY SHOCK PRECURSORS

    SciTech Connect

    Malkov, M. A.; Diamond, P. H. [CASS and Department of Physics, University of California, San Diego, La Jolla, CA 92093 (United States); Sagdeev, R. Z., E-mail: mmalkov@ucsd.edu [Department of Physics, University of Maryland, College Park, MD 20742-3280 (United States)

    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.

  3. NeuroPID: a classifier of neuropeptide precursors.

    PubMed

    Karsenty, Solange; Rappoport, Nadav; Ofer, Dan; Zair, Adva; Linial, Michal

    2014-07-01

    Neuropeptides (NPs) are short secreted peptides produced in neurons. NPs act by activating signaling cascades governing broad functions such as metabolism, sensation and behavior throughout the animal kingdom. NPs are the products of multistep processing of longer proteins, the NP precursors (NPPs). We present NeuroPID (Neuropeptide Precursor Identifier), an online machine-learning tool that identifies metazoan NPPs. NeuroPID was trained on 1418 NPPs annotated as such by UniProtKB. A large number of sequence-based features were extracted for each sequence with the goal of capturing the biophysical and informational-statistical properties that distinguish NPPs from other proteins. Training several machine-learning models, including support vector machines and ensemble decision trees, led to high accuracy (89-94%) and precision (90-93%) in cross-validation tests. For inputs of thousands of unseen sequences, the tool provides a ranked list of high quality predictions based on the results of four machine-learning classifiers. The output reveals many uncharacterized NPPs and secreted cell modulators that are rich in potential cleavage sites. NeuroPID is a discovery and a prediction tool that can be used to identify NPPs from unannotated transcriptomes and mass spectrometry experiments. NeuroPID predicted sequences are attractive targets for investigating behavior, physiology and cell modulation. The NeuroPID web tool is available at http:// neuropid.cs.huji.ac.il. PMID:24792159

  4. Siloxane and silsesquioxane molecules--precursors for silicate materials.

    PubMed

    Handke, M; Kowalewska, A

    2011-08-15

    Preparation of ceramics by sol-gel method has been known for many years, but recently it has been developed as a method for the synthesis of nanostructural ceramic materials. Hydrolytic polycondensation of simple molecules [e.g. most widely used tetraethoxysilane (TEOS)] leads to xerogel materials that can contain macromolecules of distinct random, ladder and cage or partial cage structure. In order to obtain well-defined silsesquioxanes it is preferred to start the process with more complex molecules, bringing in a specific framework that can govern the structure of the product. In the presented work alkoxy derivatives of cyclosiloxanes and polysiloxanes as well as a hydride derivative of octahedral silsequioxane (T(8)(H)) were applied as precursors in the process of hydrolytic polycondensation. Depending on the reaction conditions, silsesquioxane macromolecules or silica material of ordered structure were obtained. We have prepared mesoporous organiosilica materials without using any template or surfactant whatsoever. The meso-pores are created due to the unique structure of initial oligosiloxane or silsequioxane molecules and the specific interactions in the used catalyst/solvent system. In the case of octasilsesquioxane precursor, the condensation process gives directly mesoporous silica material. Dried polysilsesquioxanes were heated at the temperature of 600°C in argon or air atmosphere (pyrolysis or ceramization). In the atmosphere of argon SiC(x)O(y) glass materials were obtained. PMID:21030292

  5. Assembly and architecture of precursor nodes during fission yeast cytokinesis.

    PubMed

    Laporte, Damien; Coffman, Valerie C; Lee, I-Ju; Wu, Jian-Qiu

    2011-03-21

    The contractile ring is essential for cytokinesis in most fungal and animal cells. In fission yeast, cytokinesis nodes are precursors of the contractile ring and mark the future cleavage site. However, their assembly and architecture have not been well described. We found that nodes are assembled stoichiometrically in a hierarchical order with two modules linked by the positional marker anillin Mid1. Mid1 first recruits Cdc4 and IQGAP Rng2 to form module I. Rng2 subsequently recruits the myosin-II subunits Myo2 and Rlc1. Mid1 then independently recruits the F-BAR protein Cdc15 to form module II. Mid1, Rng2, Cdc4, and Cdc15 are stable node components that accumulate close to the plasma membrane. Both modules recruit the formin Cdc12 to nucleate actin filaments. Myo2 heads point into the cell interior, where they efficiently capture actin filaments to condense nodes into the contractile ring. Collectively, our work characterizing the assembly and architecture of precursor nodes defines important steps and molecular players for contractile ring assembly. PMID:21422229

  6. Malignant melanoma in a black child: predisposing precursors and management.

    PubMed Central

    Adedoyin, Olanrewaju T.; Johnson, Abdul-Wahab B. R.; Ojuawo, Ayodele I.; Afolayan, Enoch A. O.; Adeniji, Kayode A.

    2004-01-01

    Malignant melanoma (MM) remains a pediatric rarity world-wide, but perhaps more so in black Africans. To the best of our knowledge, the current report of MM in a two-and-a-half-year-old Nigerian who had a pre-existing congenital giant hairy nevus is probably the first (in an accessible literature) in a black African child. Primary neoplastic transformation and metastatic spread were suggested by the appearance of multiple swellings over the "garment" precursor nevus at the posterior trunk, multiple ipsilateral axillary nodal enlargement, and fresh occipital swellings postadmission. Smaller-sized hyperpigmented lesions with irregular, nonlobulated, and frequently hairy surfaces were also discernible over the upper and lower extremities, but the face, anterior trunk, and mucosal surfaces were relatively spared. A diagnosis of MM was confirmed by the subsequent histopathologic findings from the fine-needle aspirate and biopsy specimens. Chemotherapy was initiated but was truncated shortly after by parent-pressured discharge. Despite the rarity of MM in a tropical African setting where management options are few, the current case underscores the need for a high clinical index of diagnostic suspicion, an early pursuit of investigative confirmation, and prophylactic excision in children with the predisposing skin lesions, like congenital giant hairy nevus. An expounded discourse of the possible precursors and management options of MM is provided. We emphasize the need for institutional cost subsidy for anticancer care in tropical children. Images Figure 1 Figure 2 Figure 3 Figure 4 PMID:15540891

  7. 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

  8. The Presence of Modifiable Residues in the Core Peptide Part of Precursor Nisin Is Not Crucial for Precursor Nisin Interactions with NisB- and NisC

    PubMed Central

    Khusainov, Rustem; Kuipers, Oscar P.

    2013-01-01

    Precursor nisin is a model posttranslationally modified precursor lantibiotic that can be structurally divided into a leader peptide sequence and a modifiable core peptide part. The nisin core peptide clearly plays an important role in the precursor nisin – nisin modification enzymes interactions, since it has previously been shown that the construct containing only the nisin leader sequence is not sufficient to pull-down the nisin modification enzymes NisB and NisC. Serines and threonines in the core peptide part are the residues that NisB specifically dehydrates, and cysteines are the residues that NisC stereospecifically couples to the dehydrated amino acids. Here, we demonstrate that increasing the number of negatively charged residues in the core peptide part of precursor nisin, which are absent in wild-type nisin, does not abolish binding of precursor nisin to the modification enzymes NisB and NisC, but dramatically decreases the antimicrobial potency of these nisin mutants. An unnatural precursor nisin variant lacking all serines and threonines in the core peptide part and an unnatural precursor nisin variant lacking all cysteines in the core peptide part still bind the nisin modification enzymes NisB and NisC, suggesting that these residues are not essential for direct interactions with the nisin modification enzymes NisB and NisC. These results are important for lantibiotic engineering studies. PMID:24040355

  9. The presence of modifiable residues in the core peptide part of precursor nisin is not crucial for precursor nisin interactions with NisB- and NisC.

    PubMed

    Khusainov, Rustem; Kuipers, Oscar P

    2013-01-01

    Precursor nisin is a model posttranslationally modified precursor lantibiotic that can be structurally divided into a leader peptide sequence and a modifiable core peptide part. The nisin core peptide clearly plays an important role in the precursor nisin-nisin modification enzymes interactions, since it has previously been shown that the construct containing only the nisin leader sequence is not sufficient to pull-down the nisin modification enzymes NisB and NisC. Serines and threonines in the core peptide part are the residues that NisB specifically dehydrates, and cysteines are the residues that NisC stereospecifically couples to the dehydrated amino acids. Here, we demonstrate that increasing the number of negatively charged residues in the core peptide part of precursor nisin, which are absent in wild-type nisin, does not abolish binding of precursor nisin to the modification enzymes NisB and NisC, but dramatically decreases the antimicrobial potency of these nisin mutants. An unnatural precursor nisin variant lacking all serines and threonines in the core peptide part and an unnatural precursor nisin variant lacking all cysteines in the core peptide part still bind the nisin modification enzymes NisB and NisC, suggesting that these residues are not essential for direct interactions with the nisin modification enzymes NisB and NisC. These results are important for lantibiotic engineering studies. PMID:24040355

  10. Human Proinsulin C-peptide from a Precursor Overexpressed in Pichia pastoris

    Microsoft Academic Search

    Yang-Bin HUANG; Jiang LI; Xin GAO; Jiu-Ru SUN; Yi LU; Tao FENG; Jian FEI; Da-Fu CUI; Qi-Chang XIA; Jun REN; You-Shang ZHANG

    2006-01-01

    In this article we report the production of human proinsulin C-peptide with 31 amino acid residues from a precursor overexpressed in Pichia pastoris. A C-peptide precursor expression plasmid containing nine C-peptide genes in tandem was constructed and used to transform P. pastoris. Transformants with a high copy number of the C-peptide precursor gene integrated into the chromosome of P. pastoris

  11. Synthesis of Ni–Mo–W sulphide catalysts by ex situ decomposition of trimetallic precursors

    Microsoft Academic Search

    R. Huirache-Acuña; M. A. Albiter; J. Espino; C. Ornelas; G. Alonso-Nuñez; J. L. Rico; R. Martínez-Sánchez

    2006-01-01

    Nickel–molybdenum–tungsten sulphide unsupported catalysts were prepared by ex situ decomposition of trimetallic (Ni–Mo–W) precursors. The precursors were synthesized by impregnation of ammonium or tetraalkylammonium thiomolybdates on tungsten thiosalts (ammonium or tetraalkylammonium thiotungstates). Finally, the bimetallic precursors (Mo–W) were impregnated with Ni(NO3)2·6H2O previously dissolved in water in order to give a final molar ratio Ni:Mo:W of 2:1:1. By the ex situ

  12. An unusual presentation of precursor T cell lymphoblastic leukemia\\/lymphoma with cholestatic jaundice: case report

    Microsoft Academic Search

    Kevin J Patel; Sahibzada U Latif; Wanderley M de Calaca

    2009-01-01

    BACKGROUND: Cholestatic jaundice as a presenting symptom of Precursor T-lymphoblastic leukemia (T-ALL)\\/lymphoma (T-LBL) has never been reported in literature. Similarly, precursor T-ALL\\/T-LBL is characteristically negative for synaptophysin. We report the first case of a patient with precursor T-ALL\\/T-LBL who presented with cholestatic jaundice and aberrant tumor expression of synaptophysin. CASE REPORT: 42 year old male presented with anorexia, nausea, jaundice,

  13. Analysis of electrical brain waves in neurotoxicology: ?-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

  14. Precursor of PKKPbc: an Evidence for Core Rigidity Zone?

    NASA Astrophysics Data System (ADS)

    Wan, K.; Huang, J.; Ni, S.

    2009-05-01

    As the boundary between solid mantle and liquid outer-core, Core Mantle Boundary (CMB) is one of the most important discontinuities in the deep interior of the Earth, controlling exchange of heat, angular moment and material. Usually, the mantle side of the CMB was regarded as a complex zone, as inferred from the observation of ultra low velocity zone (ULVZ) and etc, while the core side was regarded as less complicated. Recent studies showed that ScP phases in some regions can be modeled with a thin rigidity zone at the top of the core (Rost and Revenaugh, 2001), which called core rigidity zone (CRZ), which can also explain SPdKS waveform complexities. However, mantle side core phases such as ScP may be affected by complexities from the bottom of mantle. To get some evidence for CRZ from core side reflection phase from CMB, We observed PKKPbc occurred from events in Fiji-Tonga region recorded at US networks, and compared the waveforms with Hilbert transform of direct P as PKKP is a maximum arrival phase. The main phase of them fitted well, but there's a significant pulse arriving ~1s earlier in PKKPbc waveform. This precursor indicates the existence of CRZ at the bounce point region. Then we performed waveform modeling with Reflectivity Method (Kennett and Engdahl, 1991), and got a best-fit thickness of 1.0km when the Vp,Vs and density of CRZ accord with Rost's velocity model. Although this precursor can be also explained by a liquid layer at the uppermost outer core, the thickness of the layer must be greater than 5km. Helffrich et al has limited the thickness of the layer to less than 3km in a recent research (2004). Moreover, such distinct precursor if from liquid layer must have occurred from a discontinuity with large contrast, which may result in strong following phases of PcP at short distances where PcP direct phase is weak. Thus the anomaly layer is most likely a rigidity zone. Additionally, we analyzed S and ScS waveforms on models with CRZ or ULVZ, and found that the ScS behavior caused by 1km-thick CRZ can be also explained with 10km-thick ULVZ model with -30% anomalies in S velocity. However, ULVZ model should result in clear SdS phases between S and ScS arrivals. Anyway, ScS observations should be helpful in distinguishing CRZ and ULVZ.

  15. 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.

  16. 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.

  17. Optical precursor with four-wave mixing and storage based on a cold-atom ensemble.

    PubMed

    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. PMID:25793813

  18. Variability in the precursor proteins of collagen I and III in different stages of COPD

    PubMed Central

    2010-01-01

    Background Levels of precursor proteins of collagen I and III are increased in fibrotic pulmonary diseases. This study determined whether the expression of precursors of type I and III collagen proteins would be increased in small and large airways of COPD patients in various stages of the disease reflecting fibrogenesis. Methods The levels of precursor proteins of collagen I and III were studied by immunohistochemistry and quantified by image analysis in lung tissue of 16 non-smokers, 20 smokers with normal lung function, 20 smokers with stage I-II COPD and 8 ex-smokers with stage IV COPD. Results In large airways, the subepithelial layer which was positive for precursor proteins of collagen I and III was thicker in smokers and in stage I-II COPD compared to non-smokers. Large airways in stage IV COPD showed reduced expression of precursor protein of collagen I whereas precursor of collagen III was increased. The amount of precursor protein of collagen III was increased in small airways of smokers and stage I-II COPD but reduced in stage IV COPD. Conclusions Precursor proteins of collagen I and III revealed different expression profiles in large and small airways in various stages of COPD. Smoking enhanced expression of both precursors in large airways with a positive correlation with pack-years. PMID:21118554

  19. Energetic clues to pathways to biomineralization: Precursors, clusters, and nanoparticles

    PubMed Central

    Navrotsky, Alexandra

    2004-01-01

    Nanoparticle and nanocluster precursors may play a major role in biomineralization. The small differences in enthalpy and free energy among metastable nanoscale phases offer controlled thermodynamic and mechanistic pathways. Clusters and nanoparticles offer concentration and controlled transport of reactants. Control of polymorphism, surface energy, and surface charge on nanoparticles can lead to morphological control and appropriate growth rates of biominerals. Rather than conventional nucleation and growth, assembly of nanoparticles may provide alternative mechanisms for crystal growth. The Ostwald step rule, based on a thermodynamic view of nucleation and growth, is supported by the observation that more metastable phases tend to have lower surface energies. Examples from nonbiological systems, stressing the interplay of thermodynamic and kinetic factors, illustrate features potentially important to biomineralization. PMID:15297621

  20. SEMEP: Search for Electro-Magnetic Earthquake Precursors

    NASA Astrophysics Data System (ADS)

    Parrot, M.; Walker, S. N.

    2012-12-01

    SEMEP, the Search for Electro-Magnetic Earthquake Precursors, is an EU FP7 funded project in response to the FP7-SPACE-2010-1 call for collaborative projects between the EU and Russia. The aim is to bring together satellite and ground-based data to search for possible electromagnetic perturbation effects due to seismic activity. The use of satellite observations enables the possibility of performing global surveys of the ionosphere. However, ground-based measurements are also necessary when investigating the relationship between ionospheric perturbations and seismic activity because this is the only way to connect the physical processes in the crust with the signals recorded by satellites. In this paper, first results of this project will be shown.

  1. Rhamnose Biosynthesis in Mycoplasmas Requires Precursor Glycans Larger than Monosaccharide

    PubMed Central

    Jordan, David S.; Daubenspeck, James M.; Dybvig, Kevin

    2013-01-01

    Summary Despite the apparent absence of genes coding for the known pathways for biosynthesis, the monosaccharide rhamnose was detected in the D configuration in Mycoplasma pneumoniae and Mycoplasma pulmonis, and in both the D and L configurations in Mycoplasma arthritidis. Surprisingly, the monosaccharide glucose was not a precursor for rhamnose biosynthesis and was not incorporated at detectable levels in glucose-containing polysaccharides or glycoconjugates. In contrast, carbon atoms from starch, a polymer of glucose, were incorporated into rhamnose in each of the three species examined. When grown in a serum-free medium supplemented with starch, M. arthritidis synthesized higher levels of rhamnose, with a shift in the relative amounts of the D and L configurations. Our findings suggest the presence of a novel pathway for rhamnose synthesis that is widespread in the genus Mycoplasma. PMID:23826905

  2. Preparation of a metalorganic deposition precursor for barium titanate

    SciTech Connect

    Apblett, A.W.; Georgieva, G.D.; Raygoza-Maceda, I. [Tulane Univ., New Orleans, LA (United States)

    1994-12-31

    A new, facile preparative route for BaTiO(Ox){sub 2} has been developed (Ox=oxalate). This involves passing a solution of K{sub 2}TiO(Ox){sub 2} through an ion-exchange resin to convert it to the proteo-derivative, H{sub 2}TiO(Ox){sub 2}. Treatment of the latter with BaCl{sub 2} results in precipitation of BaTiO(Ox){sub 2} with a ratio of barium:titanium of 1:1.009. Finally, reaction of BaTiO(Ox){sub 2} with refluxing methoxyacetic acid produces an alcohol and chlorocarbon soluble ceramic precursor that may be used to prepare thin films of barium titanate by metalorganic deposition.

  3. Biology and pathophysiology of the amyloid precursor protein

    PubMed Central

    2011-01-01

    The amyloid precursor protein (APP) plays a central role in the pathophysiology of Alzheimer's disease in large part due to the sequential proteolytic cleavages that result in the generation of ?-amyloid peptides (A?). Not surprisingly, the biological properties of APP have also been the subject of great interest and intense investigations. Since our 2006 review, the body of literature on APP continues to expand, thereby offering further insights into the biochemical, cellular and functional properties of this interesting molecule. Sophisticated mouse models have been created to allow in vivo examination of cell type-specific functions of APP together with the many functional domains. This review provides an overview and update on our current understanding of the pathobiology of APP. PMID:21527012

  4. Electrochemical behavior of carbon aerogels derived from different precursors

    SciTech Connect

    Pekala, R.W.; Alviso, C.T.; Nielson, J.K.; Tran, T.D. [Lawrence Livermore National Lab., CA (United States); Reynolds, G.M.; Dresshaus, M.S. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Physics

    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.

  5. Precursors for chemical and photochemical vapor deposition of copper metal

    NASA Astrophysics Data System (ADS)

    James, Alicia Marie

    The colorless square-planar cluster [CuN(SiMe3)2] 4, which contains four Cu(I) ions with four bridging amide groups, was studied as a precursor for chemical and photochemical vapor deposition of Cu metal. The cluster phosphoresces in CH2Cl2 solution and in the solid state at room temperature. Its electronic spectrum in CH 2Cl2 consists of two intense bands which are assigned to symmetry-allowed 3d ? 4p transitions; the phosphorescence is also likely to be metal-centered. Solid [CuN(SiMe3)2]4 luminesces with approximately the same spectrum as that of the CH2Cl2 solutions. At 77 K, the solid-state luminescence red-shifts slightly. The emission lifetime in glassy Et2O solution is 690 mus. [CuN(SiMe3) 2]4 deposits Cu metal via chemical vapor deposition under H2 carrier gas at substrate temperatures of 145--200°C. Deposition also occurs photochemically beginning at 136--138°C under near-UV irradiation. The preparation of monomeric derivatives of [CuN(SiMe3) 2]4 was attempted by using neutral donor ligands L (e.g. LnCuN(SiMe3)2; L = CO, PR3, CN-t-Bu; n = 1--3). The target compounds were expected to be more volatile than the copper cluster and still maintain photosensitivity. CuCl and [Cu(CH 3CN)4]PF6 were used as starting materials. Even in the presence of L, [CuN(SiMe3)2] 4 is a major product in reactions using CuCl and NaN(SiCH3) 2- [Cu(CH3CN)4]PF6 was a promising route for the monomeric Cu(I) complexes because of ready dissociation of its acetonitrile ligands. However, the characterization of these complexes was unsuccessful. Other Cu(I) amide clusters have been prepared; they may also be suitable for chemical and photochemical vapor deposition of Cu. [CuNEt2] 4, [CuN(i-Pr)2]4, and [CuN(t-Bu)(SiMe 3)]4 are phosphorescent though they are very air sensitive. They should be more volatile and produce Cu metal films more readily than [CuN(SiMe3)2]4 Cu(hfac)2 is a versatile Lewis acid, forming adducts with a variety of bases. The bases that were used were ethylene glycol, 2-methoxyethanol, propylene glycol, and 1-methoxy-2-propanol. Each Cu(hfac)2 adduct deposited Cu metal under H2 gas at a substrate temperature of 200°C and precursor temperature of 80°C. In contrast to previously known adducts with alcohols, the new precursors do not require excess alcohol vapor for stability. Nevertheless, no Cu deposition was observed with these precursors in the absence of H2 at temperatures up to 135°C.

  6. Selected Nucleic Acid Precursors in Studies of Aquatic Microbial Ecology

    PubMed Central

    Karl, David M.

    1982-01-01

    The use of radiolabeled nucleosides and nucleic acid bases to estimate the rates of RNA and DNA synthesis in naturally occurring microbial assemblages requires numerous assumptions, several of which are evaluated herein. Comparative time series analyses of the uptake and incorporation, labeling specificity, and extent of catabolism of [2-3H]adenine, [methyl-3H]thymidine, and [5-3H]uridine were performed with pure bacterial and algal cultures, as well as with environmental samples. [3H]thymidine yielded the most variable results, especially with regard to the extent of nonspecific macromolecular labeling. The pathways of [3H]thymidine and [3H]adenine metabolism were further evaluated by isotope dilution methods and by comparing incorporation patterns of thymidine labeled at different sites of the molecule. The advantages, uncertainties, and limitations of the use of radiolabeled nucleic acid precursors in studies of aquatic microbial ecology are discussed and a prospectus for future studies presented. PMID:16346114

  7. 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

  8. 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

  9. 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.

  10. Amyloid Precursor Protein Is Trafficked and Secreted via Synaptic Vesicles

    PubMed Central

    Riedel, Dietmar; Hua, Yunfeng; Hüve, Jana; Wilhelm, Benjamin G.; Klingauf, Jürgen

    2011-01-01

    A large body of evidence has implicated amyloid precursor protein (APP) and its proteolytic derivatives as key players in the physiological context of neuronal synaptogenesis and synapse maintenance, as well as in the pathology of Alzheimer's Disease (AD). Although APP processing and release are known to occur in response to neuronal stimulation, the exact mechanism by which APP reaches the neuronal surface is unclear. We now demonstrate that a small but relevant number of synaptic vesicles contain APP, which can be released during neuronal activity, and most likely represent the major exocytic pathway of APP. This novel finding leads us to propose a revised model of presynaptic APP trafficking that reconciles existing knowledge on APP with our present understanding of vesicular release and recycling. PMID:21556148

  11. Multiple Modes of Communication between Neurons and Oligodendrocyte Precursor Cells.

    PubMed

    Maldonado, Paloma P; Angulo, María Cecilia

    2015-06-01

    The surprising discovery of bona fide synapses between neurons and oligodendrocytes precursor cells (OPCs) 15 years ago placed these progenitors as real partners of neurons in the CNS. The role of these synapses has not been established yet, but a main hypothesis is that neuron-OPC synaptic activity is a signaling pathway controlling OPC proliferation/differentiation, influencing the myelination process. However, new evidences describing non-synaptic mechanisms of communication between neurons and OPCs have revealed that neuron-OPC interactions are more complex than expected. The activation of extrasynaptic receptors by ambient neurotransmitter or local spillover and the ability of OPCs to sense neuronal activity through a potassium channel suggest that distinct modes of communication mediate different functions of OPCs in the CNS. This review discusses different mechanisms used by OPCs to interact with neurons and their potential roles during postnatal development and in brain disorders. PMID:24722526

  12. Defining the membrane precursor supporting the nucleation of the phagophore.

    PubMed

    Bernard, Amélie; Klionsky, Daniel J

    2014-01-01

    How does the phagophore form? Which membrane acts as a platform for its biogenesis? Over the years, extensive use of microscopy techniques have led to the controversial identification of multiple potential membranes as precursors for phagophore nucleation and/or for the supply of lipids to the expanding compartment. Nevertheless, none of these studies has established a direct functional link between membrane sources and autophagosome biogenesis. Addressing this point, in a recent study highlighted by a punctum in this issue, Ge and coworkers developed an in vitro approach to determine the identity of the membranes responsible for the lipidation of LC3, thus identifying the ER-Golgi intermediate compartment (ERGIC) as a potential key determinant of phagophore biogenesis. PMID:24257021

  13. 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

  14. LINGO-1 promotes lysosomal degradation of amyloid-? protein precursor

    PubMed Central

    de Laat, Rian; Meabon, James S.; Wiley, Jesse C.; Hudson, Mark P.; Montine, Thomas J.; Bothwell, Mark

    2015-01-01

    Sequential proteolytic cleavages of amyloid-? protein precursor (A?PP) by ?-secretase and ?-secretase generate amyloid ? (A?) peptides, which are thought to contribute to Alzheimer's disease (AD). Much of this processing occurs in endosomes following endocytosis of A?PP from the plasma membrane. However, this pathogenic mode of processing A?PP may occur in competition with lysosomal degradation of A?PP, a common fate of membrane proteins trafficking through the endosomal system. Following up on published reports that LINGO-1 binds and promotes the amyloidogenic processing of A?PP we have examined the consequences of LINGO-1/A?PP interactions. We report that LINGO-1 and its paralogs, LINGO-2 and LINGO-3, decrease processing of A?PP in the amyloidogenic pathway by promoting lysosomal degradation of A?PP. We also report that LINGO-1 levels are reduced in AD brain, representing a possible pathogenic mechanism stimulating the generation of A? peptides in AD. PMID:25758563

  15. Teleseismic search for slow precursors to large earthquakes.

    PubMed

    Ihmlé, P F; Jordan, T H

    1994-12-01

    Some large earthquakes display low-frequency seismic anomalies that are best explained by episodes of slow, smooth deformation immediately before their high-frequency origin times. Analysis of the low-frequency spectra of 107 shallow-focus earthquakes revealed 20 events that had slow precursors (95 percent confidence level); 19 were slow earthquakes associated with the ocean ridge-transform system, and 1 was a slow earthquake on an intracontinental transform fault in the East African Rift system. These anomalous earthquakes appear to be compound events, each comprising one or more ordinary (fast) ruptures in the shallow seismogenic zone initiated by a precursory slow event in the adjacent or subjacent lithosphere. PMID:17841716

  16. Reflectance confocal microscopy: hallmarks of keratinocyte cancer and its precursors.

    PubMed

    Prow, Tarl W; Tan, Jean-Marie; Pellacani, Giovanni

    2015-01-01

    Actinic keratosis is a common result of severe sun damage and is usually present on sun-exposed skin. Reflectance confocal microscopy is a non-invasive clinical imaging modality that results in quasi-histological, en face skin images. In this chapter, we review the available literature and distill the common features of actinic keratosis, as seen by reflectance confocal microscopy. Finally, several examples are discussed in the context of matching clinical, histopathological and reflectance confocal microscopy images. Of all of the morphological features of actinic keratoses, the epidermal honeycomb pattern is the most telling when viewing the lesions using reflectance confocal microscopy. In the near future, we expect the definition of consensus criteria for diagnosing actinic keratoses and differentiating this precursor lesion. PMID:25561211

  17. Natural Modulators of Amyloid-Beta Precursor Protein Processing

    PubMed Central

    Zhang, Can; Tanzi, Rudolph E.

    2013-01-01

    Alzheimer’s 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

  18. 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.

  19. B cell precursor growth-promoting activity. Purification and characterization of a growth factor active on lymphocyte precursors

    PubMed Central

    1988-01-01

    We have used a biological assay system we developed to biochemically purify a previously uncharacterized murine lymphopoietic growth factor designated lymphopoietin 1 (LP-1). This factor is capable of stimulating the proliferation and extended maintenance of precursor cells of the B lineage. A stromal cell line producing LP-1 was established after transfection of primary stromal cultures with a plasmid encoding the transforming genes of SV40. This factor was purified to a single 25-kD species from the culture supernatant of an adherent stromal cell line. This material acts on immature lymphocytes, it binds to specific receptors on cells, and is distinct from previously described hematopoietic factors. LP-1 has been purified some 10(7)-fold with an overall recovery of 35%. The purified protein exhibits a specific activity of approximately 4 X 10(6) U/micrograms of protein and is active at a half-maximal concentration of 10(-13) M. PMID:3258354

  20. 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...

  1. 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...

  2. Controlling Mechanical Properties of Porous Mullite/Alumina Mixtures Via Precursor-Derived Alumina

    E-print Network

    Zok, Frank

    Controlling Mechanical Properties of Porous Mullite/Alumina Mixtures Via Precursor-Derived Alumina-Patterson AFB, OH 45433 This study focuses broadly on synthesis and characterization of porous mullite/alumina- ity of a precursor-derived alumina (PDA) in controlling both the modulus and the toughness of mullite

  3. Solution-based precursors in conjunction with rapid optical processing for high-quality hybrid CIGS

    Microsoft Academic Search

    Peter A. Hersh; Calvin J. Curtis; Maikel F. A. M. van Hest; Susan E. Habas; Alexander Miedaner; David S. Ginley; Billy J. Stanbery

    2011-01-01

    HelioVolt Corporation is currently developing Copper Indium Gallium Selenide (CIGS) products using a solution-based deposition of precursor films followed by 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

  4. Detection of glycosylated and deglycosylated extensin precursors by indirect competitive ELISA

    SciTech Connect

    Conrad, T.A.; Lamport, D.T.A.; Hammerschmidt, R.

    1987-01-01

    A competitive indirect enzyme-linked immunosorbent assay (ELISA) was developed for the rapid quantitation of the glycosylated and deglycosylated forms of the monomeric soluble extensin precursor subunits P1 and P2. A log-linear response range for each kind of precursor in the competition curve was between 0.01 and 100 nanograms per milliliter.

  5. Radon content of groundwater as an earthquake precursor: Evaluation of worldwide data and physical basis

    Microsoft Academic Search

    Egill Hauksson

    1981-01-01

    The properties of a worldwide data set of 91 random (222Rn) anomalies (the frequency of occurrence, the precursor time interval, and the distribution of peak amplitudes) are correlated with earthquake data such as the respective magnitude and epicentral distance. These anomalies were reported as precursors to earthquakes in the United States, USSR, China, Japan, and Iceland. Although the data set

  6. The formation of malodorous dimethyl oligosulphides in treated groundwater: the role of biofilms and potential precursors

    Microsoft Academic Search

    Peter D Franzmann; Anna Heitz; Luke R Zappia; Johannes E Wajon; Kevin Xanthis

    2001-01-01

    Water distributed from the Wanneroo Groundwater Treatment Plant intermittently contains dimethyl trisulphide (DMTS). The compound is responsible for a “swampy odour” in the water. DMTS production from potential precursors was insignificant in the absence of biofilms when compared with DMTS production from precursors in the presence of biofilms in a biofilm reactor. Greatest dimethyl disulphide (DMDS) and DMTS production (>3000ngL?1

  7. Modeling precursor diffusion and reaction of atomic layer deposition in porous structures

    SciTech Connect

    Keuter, Thomas, E-mail: t.keuter@fz-juelich.de; Menzler, Norbert Heribert; Mauer, Georg; Vondahlen, Frank; Vaßen, Robert; Buchkremer, Hans Peter [Forschungszentrum Jülich, Institute of Energy and Climate Research (IEK-1), 52425 Jülich (Germany)

    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.

  8. Small cell lung cancer cell lines secrete predominantly ACTH precursor peptides not ACTH.

    PubMed Central

    Stewart, M. F.; Crosby, S. R.; Gibson, S.; Twentyman, P. R.; White, A.

    1989-01-01

    A panel of 18 well characterised human small cell lung cancer (SCLC) cell lines was assessed for the production of adrenocorticotrophin (ACTH) and its precursor peptides, pro-opiomelanocortin (POMC) and pro-ACTH. These precursor peptides were measured directly using a novel two-site immunoradiometric assay (IRMA) based on monoclonal antibodies, in conjunction with a similar IRMA for ACTH 1-39. Significant concentrations of ACTH precursors were secreted by 10 of the 18 cell lines (56%). The low levels of ACTH immunoreactivity detected in seven cell lines could be accounted for by the known cross-reactivity of precursors in the ACTH IRMA. This suggests there is little, if any, processing of ACTH precursors to ACTH. Cell pellet extracts contained undetectable or low levels of ACTH precursors and ACTH, indicating that these peptides are not stored intracellularly. During the growth of the SCLC cells in vitro ACTH precursors accumulated progressively in the culture medium. Thus the combination of a direct assay for the ACTH precursors and the panel of SCLC cell lines provides a valuable in vitro model for the expression of POMC in human tumours. PMID:2553086

  9. Mars human precursor mission concepts for the decade 2010-2020

    Microsoft Academic Search

    Jason M. Andringa; Robert W. Easter; Andrew A. Gray; Elisabeth S. Lamassoure; Greg S. Mungas

    2005-01-01

    In the president's vision for space exploration presented in January 2004, a human precursor test bed mission series is identified for both the Moon and Mars. It is assumed that the test bed missions to Mars will satisfy measurement recommendations from the Mars human precursor science steering group (MHP SSG), the Mars exploration program analysis group (MEPAG), and the National

  10. 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…

  11. The Enzymology and Intracellular Organization of Peptide Precursor Processing: The Secretory Vesicle Hypothesis

    Microsoft Academic Search

    Harold Gainer; James T. Russell; Y. Peng Loh

    1985-01-01

    The ‘secretory vesicle hypothesis of precursor processing’ states that the initial endopeptidase cleavages which excise the nascent, biologically active peptides from their protein precursors occur primarily in secretory vesicles (or granules). Hence, all the processing steps subsequent to these cleavages must also occur within these organelles. Two types of evidence are presented in support of this view: (1) cell biological

  12. Metal Oxide Thin Films Deposited from Metal Organic Precursors in Supercritical CO2 Solutions

    E-print Network

    Gougousi, Theodosia

    Metal Oxide Thin Films Deposited from Metal Organic Precursors in Supercritical CO2 Solutions of metal oxide thin films, including Al2O3, ZrO2, MnOx, and RuOx where the metal-organic precursors-ray photoelectron spectroscopy and infrared transmission confirmed metal oxide formation. We show that hydrogen

  13. 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.

  14. Carbothermal route for preparation of boron carbide powder from boric acid–citric acid gel precursor

    Microsoft Academic Search

    A. Sinha; T. Mahata; B. P Sharma

    2002-01-01

    Boron carbide (B4C) powder has been prepared by carbothermal process using boric acid and citric acid as raw materials. Aqueous solution of boric acid in presence of citric acid forms a stable gel under controlled pH condition. The gel on subsequent pyrolysis under vacuum yields a precursor powder consisting of boron oxide and carbon. The precursor is heated under vacuum

  15. 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.

  16. Biochemical removal of HAP precursors from coal. Technical progress report, October--December 1995

    SciTech Connect

    NONE

    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.

  17. Long-range Earthquake Forecasting with Every Earthquake a Precursor According to Scale

    Microsoft Academic Search

    David A. Rhoades; Frank F. Evison

    2004-01-01

    Scaling relations previously derived from examples of the precursory scale increase before major earthquakes show that the precursor is a long-term predictor of the time, magnitude, and location of the major earthquake. These relations are here taken as the basis of a stochastic forecasting model in which every earthquake is regarded as a precursor. The problem of identifying those earthquakes

  18. Identification of the Dopamine D3 Receptor in Oligodendrocyte Precursors: Potential Role in Regulating Differentiation and

    E-print Network

    Bongarzone, Ernesto R.

    Identification of the Dopamine D3 Receptor in Oligodendrocyte Precursors: Potential Role mark- ers of specific stages of oligodendrocyte development indi- cated that D3r expression occurred in precursors and in imma- ture oligodendrocytes but not in mature oligodendrocytes (i.e., A2B5 007 01 and A2B5

  19. Atomic Layer Deposition of Hafnium and Zirconium Oxides Using Metal Amide Precursors

    E-print Network

    Atomic Layer Deposition of Hafnium and Zirconium Oxides Using Metal Amide Precursors Dennis M (ALD) of smooth and highly conformal films of hafnium and zirconium oxides was studied using six metal alkylamide precursors for hafnium and zirconium. Water was used as an oxygen source during these experiments

  20. Knowledge Management in High-Hazard Industries Accident Precursors as Practice

    Microsoft Academic Search

    JOHN S. CARROLL

    Accident precursors are events that must occur for an accident to happen in a given scenario, but that have not resulted in an accident so far. High-hazard industries, such as nuclear power and aviation, that would put many people at risk in the event of a single accident are particularly sensitive to precursors and consider them opportunities to avoid accidents.

  1. Utilization of Glutamine and of TCA Cycle Constituents as Precursors for Transmitter Glutamate and GABA

    Microsoft Academic Search

    Liang Peng; Leif Hertz; Rong Huang; Ursula Sonnewald; Steffen B. Petersen; Niels Westergaard; Orla Larsson; Arne Schousboe

    1993-01-01

    In the present review evidence is presented that (1) glutamine synthesis in astrocytes is essential for synthesis of GABA in neurons; (2) ?-ketoglutarate in the presence of alanine (as an amino group donor) can replace glutamine as a precursor for synthesis of transmitter glutamate, but maybe not as a precursor for transmitter GABA; (3) differences exist in the intraneuronal metabolic

  2. Human Haemato-Endothelial Precursors: Cord Blood CD34+ Cells Produce Haemogenic Endothelium

    E-print Network

    Paris-Sud XI, Université de

    Human Haemato-Endothelial Precursors: Cord Blood CD34+ Cells Produce Haemogenic Endothelium Elvira and haemangioblasts in later stages of development. Our studies indicate that human cord blood haematopoietic, Bordoni V, Santoro S, et al. (2012) Human Haemato-Endothelial Precursors: Cord Blood CD34+ Cells Produce

  3. Synthesis of large scorodite particles using short period time sonication to enhance agglomeration of precursor

    NASA Astrophysics Data System (ADS)

    Kitamura, Yuya; Okawa, Hirokazu; Sugawara, Katsuyasu

    2015-07-01

    The effect of various sonication frequencies (28 kHz, 200 kHz, and 1.7 MHz) on the size of synthesized scorodite particles was investigated. First, the growth of the precursor with oxidation was observed in a synthesis process using stirring. The precursor size changed with the elapsed time and was <1 µm at 0 min, approximately 1 µm at 10 min, and >3 µm at 20 min. The scorodite particles were then synthesized following different procedures such that a different size of the precursor was irradiated by each ultrasound frequency for 10 min during the oxidation process with stirring for a total duration of 180 min. For each frequency, the size of the synthesized particles varied depending on the size of the precursor. Large scorodite particles can be synthesized (70 °C) by irradiating for only 30 min at various frequencies after the size of the precursor particles reaches the optimal range.

  4. A methodology for analyzing precursors to earthquake-initiated and fire-initiated accident sequences

    SciTech Connect

    Budnitz, R.J.; Lambert, H.E.; Apostolakis, G. [and others] and others

    1998-04-01

    This report covers work to develop a methodology for analyzing precursors to both earthquake-initiated and fire-initiated accidents at commercial nuclear power plants. Currently, the U.S. Nuclear Regulatory Commission sponsors a large ongoing project, the Accident Sequence Precursor project, to analyze the safety significance of other types of accident precursors, such as those arising from internally-initiated transients and pipe breaks, but earthquakes and fires are not within the current scope. The results of this project are that: (1) an overall step-by-step methodology has been developed for precursors to both fire-initiated and seismic-initiated potential accidents; (2) some stylized case-study examples are provided to demonstrate how the fully-developed methodology works in practice, and (3) a generic seismic-fragility date base for equipment is provided for use in seismic-precursors analyses. 44 refs., 23 figs., 16 tabs.

  5. Electron Heating, Magnetic Field Amplification, and Cosmic Ray Precursor Length at Supernova Remnant Shocks

    NASA Astrophysics Data System (ADS)

    Laming, J. M.; Hwang, U.; Ghavamian, P.; Rakowski, C. E.

    2014-01-01

    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 provides 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 may be quenched either by nonresonant or resonant channels. In the former case, the cosmic rays become magnetized and amplification saturates at higher magnetic fields. The precursor can extend out to 10^17 - 10^18 cm and is potentially resolvable in Galactic supernova remnants. If the saturation occurs instead by resonant channels, the cosmic rays are scattered by turbulence and the precursor length will likely be too small to be resolvable with current instruments. 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 ? and shock velocity v_s is ? /v_s. In the nonresonantly saturated case, the precursor length declines less quickly with increasing v_s. Where precursor length proportional to 1/v_s gives constant electron heating, as observed for instance by Ghavamian et al. and van Adelsberg et al., this increased precursor length would be expected to lead to higher electron temperatures at faster supernova remnant shocks than studied by these previous works as an indirect observation of the shock precursor. Existing results and new data analysis of SN 1006 and Cas A suggests some observational support for this idea. Work supported by NASA ADAP program and by basic research funds of the Office of Naval Research.

  6. Tungsten imido complexes as precursors to tungsten carbonitride thin films.

    PubMed

    Potts, Stephen E; Carmalt, Claire J; Blackman, Christopher S; Leese, Thomas; Davies, Hywel O

    2008-11-14

    Thin films of tungsten carbonitride have been formed on glass by low-pressure chemical vapour deposition (LP)CVD at 550 degrees C from four closely related precursors: [W(mu-N(t)Bu)(N(t)Bu)Cl(2)(H(2)N(t)Bu)](2), [W(N(t)Bu)(2)Cl(2)(TMEDA)] (TMEDA = N,N,N',N'-tetramethylethylenediamine), [W(N(t)Bu)(2)Cl(2)(py)(2)] (py = pyridine) and [W(N(t)Bu)(2)Cl(N{SiMe(3)}(2))]. The grey mirror-like films were grown with a nitrogen or ammonia bleed gas. In all cases the chlorine content of the deposited films was less than 1 at% and the oxygen content of the films was lower for those grown using ammonia. Surprisingly, the use of ammonia did not significantly change the carbon content of the resulting films. Despite the coordination environment around the metal being essentially the same and the materials having a comparable volatility, some differences in film quality were observed. The films were uniform, adhesive, abrasion resistant, conformal and hard, being resistant to scratching with a steel scalpel. X-Ray powder diffraction patterns of all the films showed the formation of beta-WN(x)C(y). As a comparison the aerosol-assisted chemical vapour deposition (AA)CVD of [W(mu-N(t)Bu)(N(t)Bu)Cl(2)(H(2)N(t)Bu)](2) was investigated and amorphous tungsten carbonitride films were deposited. PMID:18941660

  7. Modeling the Transport Phenomena in the Solution Precursor Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Shan, Yanguang

    2008-10-01

    Solution precursor plasma spraying has been used to produce finely structured ceramic coatings with nano- and sub-micrometric features. This process involves the injection of a solution spray of ceramic salts into a DC plasma jet under atmospheric condition. During the process, the solvent vaporizes as the droplet travel downstream. Solid particles are finally formed due to the precipitation of the solute, and the particle are heated up and accelerated to the substrate to generate the coating. This work describes a 3D model to simulate the transport phenomena and the trajectory and heating of the solution spray in the process. The jet-spray two-way interactions are considered. A simplified model is employed to simulate the evolution process and the formation of the solid particle from the solution droplet in the plasma jet. O'Rourke's droplet collision model is used to take into account of the influence of droplet collision. The influence of droplet breakup is also considered by implementing TAB droplet breakup models into the plasma jet model. The temperature and velocity fields of the jet are obtained and validated. The particle size, velocity, temperature and position distribution on the substrate are predicted.

  8. Strategies for examination of Alzheimer's disease amyloid precursor protein isoforms.

    PubMed

    Newton, Jillian R A; Parkinson, David; Clench, Malcolm R

    2006-06-01

    We describe a proteomics procedure using bioinformatics, immunoprecipitation, two-dimensional gel electrophoresis, Western blotting, in-gel digestion, LC-MS, MALDI-MS, and MS-MS for isolation and identification of amyloid precursor protein (APP) isoforms APP695, APP751, and APP770. Retinoic acid-induced Ntera 2 cell line, derived from a human teratocarcinoma cells, was the in-vitro source of APP. Initial isolation of whole APP was performed by immunoprecipitation, using AB10, a monoclonal antibody raised to amino acids 1-17 of the beta-amyloid peptide sequence, which is present in all three alpha secretase-cleaved isoforms of interest. The next stage was separation of whole APP into its isoform components by two-dimensional gel electrophoresis. Because of low APP concentrations, detection by the usual staining methods, for example Sypro Ruby, able to detect low picomole concentrations, did not enable visualisation of the isoforms. Western analysis, however, enabled primary detection of APP, because of the inherent sensitivity of antibodies raised to specific isoform regions. This initial visualization acted as a template for excision of isoforms from 2D gels, which were then subjected to peptide mass mapping. Initial theoretical digestion of each isoform revealed the presence of specific peptides, which were then used as "tags" for isoform detection. PMID:16741768

  9. Functional Integration of Human Neural Precursor Cells in Mouse Cortex

    PubMed Central

    Zhou, Fu-Wen; Fortin, Jeff M.; Chen, Huan-Xin; Martinez-Diaz, Hildabelis; Chang, Lung-Ji; Reynolds, Brent A.; Roper, Steven N.

    2015-01-01

    This study investigates the electrophysiological properties and functional integration of different phenotypes of transplanted human neural precursor cells (hNPCs) in immunodeficient NSG mice. Postnatal day 2 mice received unilateral injections of 100,000 GFP+ hNPCs into the right parietal cortex. Eight weeks after transplantation, 1.21% of transplanted hNPCs survived. In these hNPCs, parvalbumin (PV)-, calretinin (CR)-, somatostatin (SS)-positive inhibitory interneurons and excitatory pyramidal neurons were confirmed electrophysiologically and histologically. All GFP+ hNPCs were immunoreactive with anti-human specific nuclear protein. The proportions of PV-, CR-, and SS-positive cells among GFP+ cells were 35.5%, 15.7%, and 17.1%, respectively; around 15% of GFP+ cells were identified as pyramidal neurons. Those electrophysiologically and histological identified GFP+ hNPCs were shown to fire action potentials with the appropriate firing patterns for different classes of neurons and to display spontaneous excitatory and inhibitory postsynaptic currents (sEPSCs and sIPSCs). The amplitude, frequency and kinetic properties of sEPSCs and sIPSCs in different types of hNPCs were comparable to host cells of the same type. In conclusion, GFP+ hNPCs produce neurons that are competent to integrate functionally into host neocortical neuronal networks. This provides promising data on the potential for hNPCs to serve as therapeutic agents in neurological diseases with abnormal neuronal circuitry such as epilepsy. PMID:25763840

  10. Isolation, Characterization, and Aggregation of a Structured Bacterial Matrix Precursor*

    PubMed Central

    Chai, Liraz; Romero, Diego; Kayatekin, Can; Akabayov, Barak; Vlamakis, Hera; Losick, Richard; Kolter, Roberto

    2013-01-01

    Biofilms are surface-associated groups of microbial cells that are embedded in an extracellular matrix (ECM). The ECM is a network of biopolymers, mainly polysaccharides, proteins, and nucleic acids. ECM proteins serve a variety of structural roles and often form amyloid-like fibers. Despite the extensive study of the formation of amyloid fibers from their constituent subunits in humans, much less is known about the assembly of bacterial functional amyloid-like precursors into fibers. Using dynamic light scattering, atomic force microscopy, circular dichroism, and infrared spectroscopy, we show that our unique purification method of a Bacillus subtilis major matrix protein component results in stable oligomers that retain their native ?-helical structure. The stability of these oligomers enabled us to control the external conditions that triggered their aggregation. In particular, we show that stretched fibers are formed on a hydrophobic surface, whereas plaque-like aggregates are formed in solution under acidic pH conditions. TasA is also shown to change conformation upon aggregation and gain some ?-sheet structure. Our studies of the aggregation of a bacterial matrix protein from its subunits shed new light on assembly processes of the ECM within bacterial biofilms. PMID:23632024

  11. Precursors of Executive Function in Infants With Sickle Cell Anemia

    PubMed Central

    Hogan, Alexandra M.; Telfer, Paul T.; Kirkham, Fenella J.; de Haan, Michelle

    2013-01-01

    Executive dysfunction occurs in sickle cell anemia, but there are few early data. Infants with sickle cell anemia (n = 14) and controls (n = 14) performed the “A-not-B” and Object Retrieval search tasks, measuring precursors of executive function at 9 and 12 months. Significant group differences were not found. However, for the A-not-B task, 7 of 11 sickle cell anemia infants scored in the lower 2 performance categories at 9 months, but only 1 at 12 months (P = .024); controls obtained scores at 12 months that were statistically comparable to the scores they had already obtained at 9 months. On the Object Retrieval task, 9- and 12-month controls showed comparable scores, whereas infants with sickle cell anemia continued to improve (P = .027); at 9 months, those with lower hemoglobin oxygen saturation passed fewer trials (R s = 0.670, P = .024) and took longer to obtain the toy (R s = –0.664, P = .013). Subtle delays in acquiring developmental skills may underlie abnormal executive function in childhood. PMID:22859700

  12. Amyloid precursor protein increases cortical neuron size in transgenic mice?

    PubMed Central

    Oh, Esther S.; Savonenko, Alena V.; King, Julie F.; Fangmark Tucker, Stina M.; Rudow, Gay L.; Xu, Guilian; Borchelt, David R.; Troncoso, Juan C.

    2009-01-01

    The amyloid precursor protein (APP) is the source of ?-amyloid, a pivotal peptide in the pathogenesis of Alzheimer’s disease (AD). This study examines the possible effect of APP transgene expression on neuronal size by measuring the volumes of cortical neurons (?m3) in transgenic mouse models with familial AD Swedish mutation (APPswe), with or without mutated presenilin1 (PS1dE9), as well as in mice carrying wild-type APP (APPwt). Overexpression of APPswe and APPwt protein, but not of PS1dE9 alone, resulted in a greater percentage of medium-sized neurons and a proportionate decrease in the percentage of small-sized neurons. Our observations indicate that the overexpression of mutant (APPswe) or wild-type APP in transgenic mice is necessary and sufficient for hypertrophy of cortical neurons. This is highly suggestive of a neurotrophic effect and also raises the possibility that the lack of neuronal loss in transgenic mouse models of AD may be attributed to overexpression of APP. PMID:18304698

  13. Precursor of Sunspot Penumbral Formation Discovered with Hinode SOT Observation

    NASA Astrophysics Data System (ADS)

    Shimizu, T.; Ichimoto, K.; Suematsu, Y.

    2012-05-01

    We newly found a precursory signature of sunspot penumbral formation in Ca II H images. The precursor is a dark annular zone (width 3"-5") around the umbra (pore), which was formed soon after the pore formation and existed until the penumbral formation. The penumbra was developed as if to fill the annular zone. Pre-existing ambient magnetic field islands were moved to be distributed at the outer edge of the annular zone and did not come into the zone. The observations indicate that the annular zone is different from sunspot moat flow region and that the zone is visible only in chromospheric Ca II H images, not in photospheric G-band images. We conclude that the annular zone reflects the formation of a magnetic canopy overlying the region surrounding the umbra at the chromospheric level, much before the formation of the penumbra at the photospheric level. We can predict the region and size of the penumbra, by looking at the appearance of dark zone around pores.

  14. Immunohistochemical distribution of amyloid precursor protein during normal rat development.

    PubMed

    Ohta, M; Kitamoto, T; Iwaki, T; Ohgami, T; Fukui, M; Tateishi, J

    1993-10-15

    This study focused on the immunohistochemical identification of the beta/A4 amyloid precursor protein (APP) in various developmental stages of both the rat central nervous system (CNS) and the peripheral nervous system (PNS). A comparative study with myelin basic protein (MBP) and synaptophysin (SYP) facilitated the understanding of neuronal maturation and synaptogenesis on both prenatal and postnatal development. Our immunohistochemical study revealed APP to be widely distributed through the nervous system while existing mainly in the cytoplasm, dendrites and axons of the neurons. However, immunoreactivity was also observed in either the ependymal cells or the choroid plexus epithelial cells. Our immunostaining was carried out by the hydrated autoclaving method and revealed the expression of APP at embryonic day 15 in the neuron of the mesencephalic nucleus of the trigeminal nerve and the anterior horn of the spinal cord, trigeminal and spinal ganglion, ependymal cells and the choroid plexus. We thus observed dramatic changes of APP expression in the cerebellum from the embryonic stage. The maturation of synaptogenesis in the cerebellar molecular layer was parallel to the extension of the dendrites of Purkinje cells, which revealed immunoreactivity for APP. These findings suggested that APP played an important role in neuronal maturation and synaptogenesis. Thus, APP is considered to be a useful marker for neuronal development. PMID:7505208

  15. Chemical precursors to zinc sulfide: ZnS whisker synthesis

    NASA Astrophysics Data System (ADS)

    Guiton, T. A.; Czekaj, C. L.; Rau, M. S.; Geoffroy, G. L.; Pantano, C. G.

    1988-07-01

    Currently, Chemical Vapor Deposition (CVD) derived zinc sulfide is one of the most widely used infrared optical window materials. Unfortunately, for numerous applications it does not possess optimum mechanical properties. To fabricate infrared transmitting ZnS/ZnS composites requires the development of high aspect ratio, micron sized ZnS whiskers. Although larger ZnS single crystals and whiskers have been made by a variety of high temperature routes, alternative routes have been sought for greater ZnS whisker morphology control. Low temperature organometallic routes are attractive for this purpose. The precursor compound used in this study is the known pentameric species (EtZn(SBut))5. One of the most successful routes involves the reaction of (EtZn(SBU sup t))5 with hydrogen sulfide at ambient or sub-ambient temperature to yield a precipitate which is subsequently heated under flowing H2S at 500 C to yield a mixture of sub-micron particles and single-crystal ZnS whiskers. Transmission electron micrographs of the (EtZn(SBU sup t))5 products indicate that the ZnS morphology is critically dependent on the rate of H2S reaction. Corresponding X-ray/electron diffraction, electron microscopy, elemental analysis, NMR and infrared spectroscopies have been conducted. A summary of the chemical methods, product characterization results, and proposed synthesis mechanisms are presented.

  16. Childhood bestiality: a potential precursor to adult interpersonal violence.

    PubMed

    Hensley, Christopher; Tallichet, Suzanne E; Dutkiewicz, Erik L

    2010-03-01

    Although bestiality is an infrequent form of animal cruelty, the possibility of identifying a potential link between these acts and later interpersonal violence is an area of research that deserves further exploration. In a replication of the Hensley, Tallichet, and Singer study and based on survey data from male inmates at a medium- and maximum-security prison in a southern state, the present investigation examines whether inmates who engaged in childhood bestiality (n = 23) differ from those who did not (n = 157) in terms of race, childhood residence, education, commission of a personal crime (murder, rape, robbery, aggravated/simple assault), and the number of personal crimes committed. The results revealed that respondents who had engaged in childhood bestiality were more likely to commit adult interpersonal crimes on two or more occasions as compared to those who had not engaged in bestiality. These findings lend further support to the sexually polymorphous theory that childhood bestiality may be a potential precursor to adult interpersonal violence. PMID:20124030

  17. Does a "substorm precursor" exist in the polar cap?

    NASA Astrophysics Data System (ADS)

    Nosikova, Nataliya; Lorentzen, Dag; Yagova, Nadezda; Baddeley, Lisa; Pilipenko, Vyacheslav; Kozyreva, Olga

    2015-04-01

    An isolated auroral substorm, which occurs without external triggering, can develop as a result of inner instabilities in the geomagnetic tail. The comparative analysis of presubstorm variations of the geomagnetic field and particle flux in the geomagnetic tail along with geomagnetic and auroral disturbances in the polar caps is of key importance for the discrimination between direct triggering and intra-magnetospheric processes in a substorm onset. In the present study we compare the auroral disturbances and geomagnetic pulsations in the frequency range 1-5 mHz (Pc5/Pi3) at nighttime high latitudes during both quiet geomagnetic intervals preceding isolated substorms and non-substorm intervals. Superposed epoch analysis is applied to reveal pre-substorm variations ("substorm precursors"). The data from IMAGE magnetometer network, the Meridian Scanning photometer (Svalbard), and particle flux measured by GEOTAIL, has been used. The effect of presubstorm activation (Yagova, 2000) is reproduced during the solar minimum conditions. References Yagova N., V. Pilipenko, A. Rodger, V. Papitashvili, J. Watermann, Long period ULF activity at the polar cap preceding substorm, in: Proc. 5th International Conference on Substorms, St. Peterburg, Russia (ESA SP-443), 603-606, 2000.

  18. Effects of Amphotericin B on Macrophages and Their Precursor Cells

    PubMed Central

    Lin, Hsiu-San; Medoff, Gerald; Kobayashi, George S.

    1977-01-01

    The effect of amphotericin B (AmB) treatment on the mononuclear phagocyte system of mice was investigated. Peritoneal macrophages from mice that received AmB treatment showed a higher phagocytic and antibacterial activity than those from normal untreated mice. When the levels of macrophage precursor cells in bone marrow and spleen were followed in mice after AmB treatment, an eightfold increase in the splenic content of limited stem cells for both macrophages and granulocytes (colony-forming units in culture) and a threefold increase in the number of pluripotent hemopoietic stem cells (colony-forming units in spleen) were observed on day 4. These were also accompanied by a slight increase in the colony-forming units in spleen and in culture in femoral marrows. AmB was capable of inducing a large number of peritoneal colony-forming cells in the peritoneum, and caused a significant rise in the serum level of colony-stimulating factor. No significant change in the level of blood monocytes was noted, although a transient increase in the proportion of neutrophils was observed within 24 h after AmB treatment. PMID:836011

  19. Risk and return: evaluating Reverse Tracing of Precursors earthquake predictions

    NASA Astrophysics Data System (ADS)

    Zechar, J. Douglas; Zhuang, Jiancang

    2010-09-01

    In 2003, the Reverse Tracing of Precursors (RTP) algorithm attracted the attention of seismologists and international news agencies when researchers claimed two successful predictions of large earthquakes. These researchers had begun applying RTP to seismicity in Japan, California, the eastern Mediterranean and Italy; they have since applied it to seismicity in the northern Pacific, Oregon and Nevada. RTP is a pattern recognition algorithm that uses earthquake catalogue data to declare alarms, and these alarms indicate that RTP expects a moderate to large earthquake in the following months. The spatial extent of alarms is highly variable and each alarm typically lasts 9 months, although the algorithm may extend alarms in time and space. We examined the record of alarms and outcomes since the prospective application of RTP began, and in this paper we report on the performance of RTP to date. To analyse these predictions, we used a recently developed approach based on a gambling score, and we used a simple reference model to estimate the prior probability of target earthquakes for each alarm. Formally, we believe that RTP investigators did not rigorously specify the first two `successful' predictions in advance of the relevant earthquakes; because this issue is contentious, we consider analyses with and without these alarms. When we included contentious alarms, RTP predictions demonstrate statistically significant skill. Under a stricter interpretation, the predictions are marginally unsuccessful.

  20. Isolation of gibberellin precursors from heavily pigmented tissues.

    PubMed

    Metzger, J D; Hazebroek, J P

    1989-12-01

    The kauranoid precursors of gibberellins are difficult to isolate from heavily pigmented plant tissues. In this paper, we describe relatively simple and efficient procedures for the purification of these compounds from tissues containing chlorophyll and other high molecular weight pigments. Extracts of shoots from Thlaspi arvense L. were subjected first to size exclusion chromatography using ethyl acetate as the eluting solvent. This procedure resulted in the separation of kauranoids as a class of compounds from chlorophyll. Typically, a 90% reduction in mass of the kauranoid enriched-fraction was observed. This fraction was subjected to reverse phase high performance liquid chromatography and individual fractions analyzed by combined gas chromatography-mass spectrometry. Five kauranoids were identified in shoot extracts of T. arvense: ent-kaur-16-ene, ent-kaur-16-en-19-ol, ent-kaur-16-en-19-oic acid, trachylobanoic acid, and 7beta, 13-dihydroxykaurenolide. The metabolic relationships of these compounds to the gibberellins previously identified in this species (JD Metzger, MC Mardaus [1986] Plant Physiol 80: 396-402) are discussed. In addition, the utility of size exclusion chromatography in preparative situations is demonstrated by the purification of ent-kaurenoic acid in milligram quantities from the florets of Helianthus annuus L. PMID:16667206

  1. Impact of simulated solar irradiation on disinfection byproduct precursors.

    PubMed

    Chow, Alex T; Leech, Dina M; Boyer, Treavor H; Singer, Philip C

    2008-08-01

    The Sacramento-San Joaquin Delta is the major drinking water source for 23 million California residents. Consequently, many studies have examined disinfection byproduct (DBP) formation in relation to Delta dissolved organic carbon (DOC) concentration. However, DOC characteristics within the Delta are not the same as those entering downstream water treatment facilities. As water is transferred to Southern California through the California Aqueduct, a 714.5 km-open channel, it is exposed to sunlight, potentially altering DBP precursors. We collected water from three sites within the Delta and one nearthe California Aqueduct, representing different DOC sources, and irradiated them in a solar simulator at a dose equivalent to that received during four days conveyance in the aqueduct. Photolytic changes in DOC were assessed by measuring CO2 and organic acid production, fluorescence, and ultraviolet absorbance over time. Trihalomethane (THM) and haloacetic acid (HAA) formation potentials, as well as the distribution of hydrophobic, transphilic, and hydrophilic acid fractions were determined at exposures equivalent to one and four days. Solar irradiation significantly decreased ultraviolet absorbance and fluorescence intensity, produced organic acids, and increased the hydrophilic fraction of waters. These changes in DOC caused a shift in bromine incorporation among the THM and HAA species. Our results are the first to demonstrate the importance of sunlight in altering DOC with respect to DBP formation. PMID:18754480

  2. Synthesis of 9-oxononanoic acid, a precursor for biopolymers.

    PubMed

    Otte, Konrad B; Kirtz, Marko; Nestl, Bettina M; Hauer, Bernhard

    2013-11-01

    Polymers based on renewable resources have become increasingly important. The natural functionalization of fats and oils enables an easy access to interesting monomeric building blocks, which in turn transform the derivative biopolymers into high-performance materials. Unfortunately, interesting building blocks of medium-chain length are difficult to obtain by traditional chemical means. Herein, a biotechnological pathway is established that could provide an environmentally suitable and sustainable alternative. A multiple enzyme two-step one-pot process efficiently catalyzed by a coupled 9S-lipoxygenase (St-LOX1, Solanum tuberosum) and 9/13-hydroperoxide lyase (Cm-9/13HPL, Cucumis melo) cascade reaction is proposed as a potential route for the conversion of linoleic acid into 9-oxononanoic acid, which is a precursor for biopolymers. Lipoxygenase catalyzes the insertion of oxygen into linoleic acid through a radical mechanism to give 9S-hydroperoxy-octadecadienoic acid (9S-HPODE) as a cascade intermediate, which is subsequently cleaved by the action of Cm-9/13HPL. This one-pot process afforded a yield of 73?% combined with high selectivity. The best reaction performance was achieved when lipoxygenase and hydroperoxide lyase were applied in a successive rather than a simultaneous manner. Green leaf volatiles, which are desired flavor and fragrance products, are formed as by-products in this reaction cascade. Furthermore, we have investigated the enantioselectivity of 9/13-HPLs, which exhibited a strong preference for 9S-HPODE over 9R-HPODE. PMID:23934656

  3. Seismic event classification and precursor identification at Fuego Volcano, Guatemala

    NASA Astrophysics Data System (ADS)

    Brill, K. A.; Waite, G. P.; Rodriguez, K.

    2013-12-01

    Understanding the nature and origins of seismic signals generated by volcanic activity can greatly aid in hazard mitigation efforts. Systematic identification and detailed cataloging of explosive events provide a first step for this understanding, and can be even more valuable when the events span longer time periods. Beyond simply being a more useful monitoring tool, the detailed classification of events can illuminate the processes behind different conduit flow phenomena such as rheological sealing or piston-style chugging. Fuego volcano, Guatemala, is a basaltic-andesite stratovolcano that has been continually active since 1999. Activity is characterized by small-scale explosive eruptions and intermittent lava flows. In this study, we categorize different events recorded with a 10 station temporary seismic array at Fuego volcano in Guatemala in January 2012 that included infrasound and tilt sensors. Waveform analysis, along with visual and thermal characteristics captured by cameras allow us to identify precursory activity in different bandwidths that precedes some of the event types. We investigate the physical mechanisms behind these precursors to explain why some event types exhibit them while others may not, and how these mechanisms influence our conceptual models of explosion dynamics at Fuego. Finally, we compare events recorded in 2012 with other studies conducted at Fuego volcano in previous years to identify changes in the signal characteristics and their potential influences on activity styles observed during different field campaigns to highlight the importance of longitudinal studies at persistently active volcanic systems.

  4. The "Support to Precursor Space Situational Awareness Services" (SPA) Project

    NASA Astrophysics Data System (ADS)

    Valero, J. L.; Albani, S.; Gallardo, B.; Matute, J.; O'Dwyer, A.

    2012-01-01

    Space activities are increasingly important in areas such as environment, science, navigation and security. Space Situational Awareness (SSA) refers to the knowledge of location and function of space objects and the space environment. The development of an SSA capability will allow the European Union (EU) and its Member States to better use space, strengthening their security and economy. The "Support to Precursor space situational Awareness services" (SPA) project is an FP7 Support Action managed by the European Union Satellite Centre (EUSC) under the full control of EU Member States and implemented with the collaboration of SSA Key Stakeholders. SPA is studying possible SSA Governance and Data Policy models in the EUSC secure environment by experimenting with a number of SSA preliminary services relevant to civilian security and to the Common Foreign and Security Policy (CFSP) such as Satellite Over-flight, Satellite Conjunction Warning and Space Re-entry Prediction. The final output of the SPA project will be a report providing recommendations for further development of SSA in Europe, particularly on the technical aspects of its Governance and Data Policy.

  5. Precursors of lethal violence: a death row sample.

    PubMed

    Freedman, D; Hemenway, D

    2000-06-01

    A qualitative methodology based on the standards of criminal defense investigation was used to analyze the social and family histories of 16 men sentenced to death in California. Using a multisource cross-validation methodology, we assessed patterns of impairment, injury and deficit at each of four ecological levels: family, individual, community and social institutions. Investigation documented consistent and pervasive patterns of serious impairment, injury and deficit across the cases and levels. The men share numerous risk factors and few resiliency factors associated with violence. We found family violence in all 16 cases, including severe physical and/or sexual abuse in 14 cases; individual impairments in 16, including 14 with post-traumatic stress disorder, 13 with severe depression and 12 with histories of traumatic brain injury; community isolation and violence in 12; and institutional failure in 15, including 13 cases of severe physical and/or sexual abuse while in foster care or under state youth authority jurisdiction. Appropriate interventions might have made a difference in reducing lethal violence and its precursor conditions. PMID:10798330

  6. Preparation of zinc sulfide nanocrystallites from single-molecule precursors

    NASA Astrophysics Data System (ADS)

    Palve, Anil M.; Garje, Shivram S.

    2011-07-01

    Zinc sulfide nanocrystallites were prepared using Zinc(II) thiosemicarbazone complexes of the types Zn(L) 2 and ZnCl 2(LH) 2 (where, LH=thiosemicarbazones of cinnamaldehyde, 4-chlorobenzaldehyde, indol-3-carboxaldehyde and thiophene-2-carboxaldehyde) as single source precursors by solvothermal decomposition in ethylene glycol and ethylene diamine in few cases. The materials were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction, energy dispersive X-ray analysis and UV-vis and IR spectroscopy. Solvothermal decomposition in ethylene glycol resulted in the formation of hexagonal ZnS (JCPDS: 36-1450) as evident from the XRD patterns. However, XRD shows formation of hybrid material, ZnS 0.5EN in case of solvothermal decomposition in ethylenediamine. Infrared spectra authenticate the capping of ethylene glycol and ethylenediamine on ZnS and ZnS 0.5EN, respectively. TEM images showed formation of spherical nanoparticles for the materials obtained from ethylene glycol, whereas plate-like morphology is observed in case of materials obtained from ethylene diamine. The blue shift of absorption bands compared to bands of bulk materials in the UV-vis spectra supports the formation of smaller particles.

  7. Preparation of cuxinygazsen precursor films and powders by electroless deposition

    DOEpatents

    Bhattacharya, Raghu N. (Littleton, CO); Batchelor, Wendi Kay (Lakewood, CO); Wiesner, Holm (Golden, CO); Ramanathan, Kannan (Golden, CO); Noufi, Rommel (Golden, CO)

    1999-01-01

    A method for electroless deposition of Cu.sub.x In.sub.y Ga.sub.z Se.sub.n (x=0-2, y=0-2, z=0-2, n=0-3) precursor films and powders onto a metallic substrate comprising: preparing an aqueous bath solution of compounds selected from the group consisting of: I) a copper compound, a selenium compound, an indium compound and gallium compound; II) a copper compound, a selenium compound and an indium compound; III) a selenium compound, and indium compound and a gallium compound; IV) a selenium compound and a indium compound; and V) a copper compound and selenium compound; each compound being present in sufficient quantity to react with each other to produce Cu.sub.x In.sub.y Ga.sub.z Se.sub.n (x=0-2, y=0-2, z=0-2, n=0-3); adjusting the pH of the aqueous bath solution to an acidic value by the addition of a dilute acid; and initiating an electroless reaction with an oxidizing counterelectrode for a sufficient time to cause a deposit of Cu.sub.x In.sub.y Ga.sub.z Se.sub.n (x=0-2, y=0-2, z=0-2, n=0-3) from the aqueous bath solution onto a metallic substrate.

  8. Malondialdehyde precursors in gamma-irradiated DNA, deoxynucleotides and deoxynucleosides.

    PubMed Central

    Janicek, M F; Haseltine, W A; Henner, W D

    1985-01-01

    Gamma-irradiation of DNA, deoxynucleosides, or deoxynucleotides produces material that reacts with thiobarbituric acid to form a chromophore with maximum absorbance at 532 nm. This material is not malondialdehyde. We have identified a new radiation product (thymin-1'-yl)-propenal as the TBA-reactive product of gamma-irradiation of thymidine. Thymine-propenal has been described by other investigators as a product of bleomycin-treatment of DNA. Irradiation of thymidine nucleotides produces phosphorylated precursors to thymine-propenal. Studies of the requirements for formation of TBA-reactivity indicate a mechanism involving reaction of a free radical with the deoxyribose moiety and molecular oxygen. On the basis of these results it is proposed that gamma-irradiation produces TBA-reactive material in DNA by the same reaction sequence in which bleomycin catalyzes the formation of base-propenals in DNA. Bleomycin and gamma-irradiation differ in the extent to which the sequence proceeds to completion with release of free base-propenals. PMID:4080556

  9. Analytical characterization of wine and its precursors by capillary electrophoresis.

    PubMed

    Gomez, Federico J V; Monasterio, Romina P; Vargas, Verónica Carolina Soto; Silva, María F

    2012-08-01

    The accurate determination of marker chemical species in grape, musts, and wines presents a unique analytical challenge with high impact on diverse areas of knowledge such as health, plant physiology, and economy. Capillary electromigration techniques have emerged as a powerful tool, allowing the separation and identification of highly polar compounds that cannot be easily separated by traditional HPLC methods, providing complementary information and permitting the simultaneous analysis of analytes with different nature in a single run. The main advantage of CE over traditional methods for wine analysis is that in most cases samples require no treatment other than filtration. The purpose of this article is to present a revision on capillary electromigration methods applied to the analysis of wine and its precursors over the last decade. The current state of the art of the topic is evaluated, with special emphasis on the natural compounds that have allowed wine to be considered as a functional food. The most representative revised compounds are phenolic compounds, amino acids, proteins, elemental species, mycotoxins, and organic acids. Finally, a discussion on future trends of the role of capillary electrophoresis in the field of analytical characterization of wines for routine analysis, wine classification, as well as multidisciplinary aspects of the so-called "from soil to glass" chain is presented. PMID:22887148

  10. Tsunami precursors excited by surface seismic waves during the 2011 Tohoku earthquake

    NASA Astrophysics Data System (ADS)

    Sementsov, Kirill A.; Nosov, Mikhail A.; Kolesov, Sergey V.; Matsumoto, Hiroyuki

    2015-04-01

    Weak gravitational waves that preceded the arrival of tsunami were registered by the DONET (JAMSTEC) stations during the 2011 Tohoku earthquake. We shall call these waves tsunami precursors. The amplitude and period of tsunami precursors amounted to 3 cm and 150 s, respectively. Tsunami precursors are clearly manifested in ocean-bottom pressure variations recorded by DONET stations that were in operation during the 2011 event. Being excited immediately after the passage of surface seismic waves the precursors were observed during at least one hour until the arrival of tsunami waves. Ocean bottom seismometers (accelerometers) did not detect any similar signals within the same time-frequency range. We assume physical mechanism of generation of the precursor is related to low-frequency seismic surface waves. Theoretical estimates of parameters of the precursor carried out on the base of this assumption are in a good agreement with the observed values. Results of 3D numerical simulation of tsunami precursors carried out in the framework of linear potential theory are presented and analyzed. The study was supported by Russian Foundation for Basic Research (projects 13-05-92100, 13-05-00337).

  11. GH Mediates Exercise-Dependent Activation of SVZ Neural Precursor Cells in Aged Mice

    PubMed Central

    Blackmore, Daniel G.; Vukovic, Jana; Waters, Michael J.; Bartlett, Perry F.

    2012-01-01

    Here we demonstrate, both in vivo and in vitro, that growth hormone (GH) mediates precursor cell activation in the subventricular zone (SVZ) of the aged (12-month-old) brain following exercise, and that GH signaling stimulates precursor activation to a similar extent to exercise. Our results reveal that both addition of GH in culture and direct intracerebroventricular infusion of GH stimulate neural precursor cells in the aged brain. In contrast, no increase in neurosphere numbers was observed in GH receptor null animals following exercise. Continuous infusion of a GH antagonist into the lateral ventricle of wild-type animals completely abolished the exercise-induced increase in neural precursor cell number. Given that the aged brain does not recover well after injury, we investigated the direct effect of exercise and GH on neural precursor cell activation following irradiation. This revealed that physical exercise as well as infusion of GH promoted repopulation of neural precursor cells in irradiated aged animals. Conversely, infusion of a GH antagonist during exercise prevented recovery of precursor cells in the SVZ following irradiation. PMID:23209615

  12. Oligogermanes as molecular precursors for germanium(0) nanoparticles: Size control and size-dependent fluorescence

    SciTech Connect

    Schrick, Aaron C.; Weinert, Charles S., E-mail: weinert@chem.okstate.edu

    2013-10-15

    Graphical abstract: Catenated germanium compounds are employed as molecular precursors for germanium(0) nanoparticles. The size of the nanoparticles, and their fluorescence spectra, depend on the number of catenated germanium atoms present in the precursor. - Highlights: • We have used oligogermanes for the size-specific synthesis of germanium(0) nanoparticles. • The size of the nanomaterials obtained depends directly on the degree of catenation present in the oligogermane precursor. • The nanoparticles are shown to exhibit size-dependent fluorescence. • Oligogermanes will function as useful precursors for the synthesis of a variety of nanomaterials. - Abstract: Germanium nanoparticles were synthesized in solution from novel oligogermane molecular precursors. The size of the nanoparticles obtained is directly related to the number of catenated germanium atoms present in the oligogermane precursor and the nanoparticles exhibit size-dependent fluorescence. The germanium nanoparticles were also characterized by TEM, powder XRD, FTIR, EDS and XPS methods. This method appears to be a promising new route for the synthesis of germanium nanoparticles since the size of the materials obtained can be controlled by the choice of the oligogermane used as the precursor.

  13. Normal sulfation levels regulate spinal cord neural precursor cell proliferation and differentiation

    PubMed Central

    2012-01-01

    Background Sulfated glycosaminoglycan chains are known for their regulatory functions during neural development and regeneration. However, it is still unknown whether the sulfate residues alone influence, for example, neural precursor cell behavior or whether they act in concert with the sugar backbone. Here, we provide evidence that the unique 473HD-epitope, a representative chondroitin sulfate, is expressed by spinal cord neural precursor cells in vivo and in vitro, suggesting a potential function of sulfated glycosaminoglycans for spinal cord development. Results Thus, we applied the widely used sulfation inhibitor sodium chlorate to analyze the importance of normal sulfation levels for spinal cord neural precursor cell biology in vitro. Addition of sodium chlorate to spinal cord neural precursor cell cultures affected cell cycle progression accompanied by changed extracellular signal-regulated kinase 1 or 2 activation levels. This resulted in a higher percentage of neurons already under proliferative conditions. In contrast, the relative number of glial cells was largely unaffected. Strikingly, both morphological and electrophysiological characterization of neural precursor cell-derived neurons demonstrated an attenuated neuronal maturation in the presence of sodium chlorate, including a disturbed neuronal polarization. Conclusions In summary, our data suggest that sulfation is an important regulator of both neural precursor cell proliferation and maturation of the neural precursor cell progeny in the developing mouse spinal cord. PMID:22681904

  14. Precursors to potential severe core damage accidents: 1994, a status report. Volume 22: Appendix I

    SciTech Connect

    Belles, R.J.; Cletcher, J.W.; Copinger, D.A.; Vanden Heuvel, L.N. [Oak Ridge National Lab., TN (United States)] [Oak Ridge National Lab., TN (United States); Dolan, B.W.; Minarick, J.W. [Oak Ridge National Lab., TN (United States)] [Oak Ridge National Lab., TN (United States); [Science Applications International Corp., Oak Ridge, TN (United States)

    1995-12-01

    Nine operational events that affected eleven commercial light-water reactors (LWRs) during 1994 and that are considered to be precursors to potential severe core damage are described. All these events had conditional probabilities of subsequent severe core damage greater than or equal to 1.0 {times} 10{sup {minus}6}. These events were identified by computer-screening the 1994 licensee event reports from commercial LWRs to identify those that could be potential precursors. Candidate precursors were then selected and evaluated in a process similar to that used in previous assessments. Selected events underwent engineering evaluation that identified, analyzed, and documented the precursors. Other events designated by the Nuclear Regulatory Commission (NRC) also underwent a similar evaluation. Finally, documented precursors were submitted for review by licensees and NRC headquarters and regional offices to ensure that the plant design and its response to the precursor were correctly characterized. This study is a continuation of earlier work, which evaluated 1969--1981 and 1984--1993 events. The report discusses the general rationale for this study, the selection and documentation of events as precursors, and the estimation of conditional probabilities of subsequent severe core damage for events. This document is bound in two volumes: Vol. 21 contains the main report and Appendices A--H; Vol. 22 contains Appendix 1.

  15. Distinct P-glycoprotein precursors are overproduced in independently isolated drug-resistant cell lines.

    PubMed Central

    Greenberger, L M; Lothstein, L; Williams, S S; Horwitz, S B

    1988-01-01

    A family of P-glycoproteins are overproduced in multidrug-resistant cells derived from the murine macrophage-like line J774.2. To determine whether individual family members are overproduced in response to different drugs, the P-glycoprotein precursors in several independently isolated cell lines, which were selected for resistance to vinblastine or taxol, were compared. Individual cell lines selected with vinblastine overproduced P-glycoprotein precursors of either 120 or 125 kDa. Taxol-selected cell lines overproduced either the 125-kDa precursor or both precursors simultaneously. Two similar but distinct peptide maps for the mature P-glycoproteins were observed. These maps corresponded to each precursor regardless of the drug used for selection. One vinblastine-resistant cell line switched from the 125- to the 120-kDa precursor when grown in increasing concentrations of drug. This change coincided with the overexpression of a distinct subset of mRNA species that code for P-glycoprotein. It is concluded that precursor expression is not drug-specific. These data suggest that individual overproduced P-glycoprotein family members are translated as distinct polypeptides. The results may help to explain the diversity in the multidrug-resistant phenotype. Images PMID:2897689

  16. Effect of vanadium on synthesis of WC nanopowders by thermal processing of V-doped tungsten precursor

    Microsoft Academic Search

    Cholsong Pang; Zhimeng Guo; Ji Luo; Ting Hou; Jiang Bing

    2010-01-01

    The effect of vanadium on the synthesis of WC nanopowders by carbon thermal processing of V-doped tungsten precursor has been discussed. The V-doped tungsten precursor was prepared by a wet chemical method with ammonium tungstate and ammonium vanadate as its starting materials. The precursor was carbonized in the vacuum furnace using phenol formaldehyde resin as a carbon agent. The results

  17. Secretory Expression of Insulin Precursor in Pichia pastoris and Simple Procedure for Producing Recombinant Human Insulin

    Microsoft Academic Search

    T. Xie; Q. Liu; F. Xie; H. Liu; Y. Zhang

    2008-01-01

    In this work, Pichia pastoris was applied to produce human insulin by a simple procedure. The synthesized insulin precursor (ILP) gene was inserted into pPIC9K to obtain secretary expression plasmid pPIC9K\\/ILP. Pichia pastoris GS115 was transformed by pPIC9K\\/ILP and the high expresser was screened. In a 16 L fermentor, the insulin precursor production was 3.6 g\\/L. Insulin precursor, purified by one-step chromatography,

  18. Non-affine fluctuations and the statistics of defect precursors in the planar honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Mitra, Amartya; Ganguly, Saswati; Sengupta, Surajit; Sollich, Peter

    2015-06-01

    Certain localised displacement fluctuations in the planar honeycomb lattice may be identified as precursors to topological defects. We show that these fluctuations are among the most pronounced non-affine distortions of an elemental coarse graining volume of the honeycomb structure at non zero temperatures. We obtain the statistics of these precursor modes in the canonical ensemble, evaluating exactly their single point and two-point spatio-temporal distributions, for a lattice with harmonic nearest neighbour and next near neighbour bonds. As the solid is destabilised by tuning interactions, the precursor fluctuations diverge and correlations become long-lived and long-ranged.

  19. Atomic layer deposition of hafnium oxide and hafnium silicate thin films using liquid precursors and ozone

    Microsoft Academic Search

    Yoshihide Senzaki; Seung Park; Hood Chatham; Lawrence Bartholomew; Wesley Nieveen

    2004-01-01

    Atomic layer deposition (ALD) processes for HfO2 and HfxSi1-xO2 high-k dielectric thin films using liquid precursors and ozone were evaluated. Tetrakis(ethylmethylamino)hafnium (TEMAHf) precursor provides HfO2 films with superior quality as compared to Hf(t-butoxide)4 precursor in terms of deposition rate, purity, and electrical properties of the films. ALD processes for hafnium silicate films have been developed by co-injection of TEMAHf and

  20. Multiple distinct small RNAs originate from the same microRNA precursors

    Microsoft Academic Search

    Weixiong Zhang; Shang Gao; Xuefeng Zhou; Jing Xia; Padmanabhan Chellappan; Xiang Zhou; Xiaoming Zhang; Hailing Jin

    2010-01-01

    BACKGROUND: MicroRNAs (miRNAs), which originate from precursor transcripts with stem-loop structures, are essential gene expression regulators in eukaryotes. RESULTS: We report 19 miRNA precursors in Arabidopsis that can yield multiple distinct miRNA-like RNAs in addition to miRNAs and miRNA*s. These miRNA precursor-derived miRNA-like RNAs are often arranged in phase and form duplexes with an approximately two-nucleotide 3'-end overhang. Their production

  1. Cleavage of a Viral Envelope Precursor During the Morphogenesis of Sindbis Virus

    PubMed Central

    Jones, Kenneth J.; Waite, Marilynn R. F.; Bose, H. R.

    1974-01-01

    In cells infected with a temperature-sensitive mutant of Sindbis virus, the cleavage of the precursor to one of the viral envelope proteins does not occur at the nonpermissive temperature. This precursor is found associated with the plasma membrane fraction obtained from the infected cell. Since this is the site at which the virus matures, this finding suggests that during Sindbis virus replication the precursor to the smaller proteins associates with the cell membrane and is then cleaved during the maturation of the virus. PMID:4821491

  2. Vesicles in Experimental Chondrules as Clues to Chondrule Precursors

    NASA Astrophysics Data System (ADS)

    Maharaj, S. V.; Hewins, R. H.

    1993-07-01

    The processing of chondrule precursors during melting is so extensive that there are few unambiguous indicators of their mineralogical composition. The specific combination of peak temperature and heating time, i.e., the heating mechanism, is also unknown. The general absence of vesicles in chondrules is a potential constraint on both questions. Meteor ablation spherules, whose origins are well understood, differ from chondrules in having abundant vesicles [1]. Chondrules simulated experimentally in a variety of ways have vesicles in many cases, but it has been suggested that the presence of vesicles rules out flash heating [2]. We therefore examine in detail the formation of vesicles in synthetic chondrules. Vesicles have been produced in experiments with long heating times [3] as well as short [2]. They are most prominent in charges that experienced low degrees of melting, probably because of surface tension effects that trap bubbles between relict grains, aided by high melt viscosity. The gas could be derived from air trapped when the powdered sample is prepared, binding agents (acetone, water), or volatiles in the starting minerals (Na, H2O). We have conducted experiments to determine the source of vesicles in synthetic chondrules initially heated slightly below the liquidus and cooled at 500 degrees C/hr. Runs made in pairs included charges with and without acetone binder and charges baked out at 200 degrees C for different lengths of time. Charges with acetone produced more vesicles, which could be avoided to some extent by preliminary baking. Charges with no binder had very few vesicles if baked for 1/2 hour. Vesicles are more prominent when using a well-sorted fine-grained powder than with an unsorted more uniform size distribution. Pulling a vacuum on pellets had no effect on subsequent vesicle development. Vesicles are unlikely to be due to loss of Na from the charge, because vesicles are equally prevalent in flash-heated charges, which retain most of their Na, and earlier experiments that spent longer times at temperature. Experiments with serpentine in the starting materials resulted in a popcorn vesicle texture with voids as large as 3 mm, like some ablation spherules [1]. Trapped air and binding agents cause most vesicles in experimental charges. Chondrule precursors must have consisted of olivine, etc., with no hydrous minerals, assembled at low pressure, or they would have generated vesicles. The absence of vesicles in chondrules does not rule out flash heating mechanisms. References: [1] Brownlee D. E. et al. (1983) In Chondrules and Their Origin (E. A. King, ed.), 10-25, LPI, Houston. [2] Wdowiak T. J. (1983) In Chondrules and Their Origin (E. A. King, ed.), 279-283, LPI, Houston. [3] Radomsky P. M. and Hewins R. H. (1990) GCA, 54, 3475-3490.

  3. Distinguishing closely related amyloid precursors using an RNA aptamer.

    PubMed

    Sarell, Claire J; Karamanos, Theodoros K; White, Simon J; Bunka, David H J; Kalverda, Arnout P; Thompson, Gary S; Barker, Amy M; Stockley, Peter G; Radford, Sheena E

    2014-09-26

    Although amyloid fibrils assembled in vitro commonly involve a single protein, fibrils formed in vivo can contain multiple protein sequences. The amyloidogenic protein human ?2-microglobulin (h?2m) can co-polymerize with its N-terminally truncated variant (?N6) in vitro to form hetero-polymeric fibrils that differ from their homo-polymeric counterparts. Discrimination between the different assembly precursors, for example by binding of a biomolecule to one species in a mixture of conformers, offers an opportunity to alter the course of co-assembly and the properties of the fibrils formed. Here, using h?2m and its amyloidogenic counterpart, ??6, we describe selection of a 2'F-modified RNA aptamer able to distinguish between these very similar proteins. SELEX with a N30 RNA pool yielded an aptamer (B6) that binds h?2m with an EC50 of ?200 nM. NMR spectroscopy was used to assign the (1)H-(15)N HSQC spectrum of the B6-h?2m complex, revealing that the aptamer binds to the face of h?2m containing the A, B, E, and D ?-strands. In contrast, binding of B6 to ?N6 is weak and less specific. Kinetic analysis of the effect of B6 on co-polymerization of h?2m and ?N6 revealed that the aptamer alters the kinetics of co-polymerization of the two proteins. The results reveal the potential of RNA aptamers as tools for elucidating the mechanisms of co-assembly in amyloid formation and as reagents able to discriminate between very similar protein conformers with different amyloid propensity. PMID:25100729

  4. Identifying Precursors to the 2009 South Pacific tsunami?

    NASA Astrophysics Data System (ADS)

    Goff, J. R.; Chague-Goff, C.; Etienne, S.; Lamarche, G.; Pelletier, B.; Richmond, B. M.; Strotz, L. C.; Buckley, M. L.; Wilson, K.; Dudley, W. C.; Urban, G.; Sale, M.; Dominey-Howes, D.

    2009-12-01

    The 29/30 September 2009 tsunami was a truly South Pacific event, spanning the dateline and affecting Samoa, American Samoa, Tonga, Fiji, Wallis & Futuna, and the Marquesas. Notable historical tsunamis in the region include the 1960 Chilean tsunami and a 1917 one from a source similar to the 2009 event. The historic record of large tsunamis varies between Pacific Island Countries (PICs), but it is short, rarely exceeding 200 years. It is sufficiently long however, to indicate that the tsunami hazard in the region may be high, but sufficiently short to give an extremely limited understanding of the hazard. Sadly, there are almost no South Pacific palaeotsunami data available to give a longer time and magnitude record of potential precursor events. Core and trench work in Samoa and Wallis & Futuna reveals evidence for several possible palaeotsunamis. There are up to six sand layers with associated paleosols in Samoa, and up to four in Futuna. At Tavai in Futuna, there is also an oral tradition associated with evidence of a surface boulder scatter field, and probably a sand layer overlying a past occupation site. These data are compelling and a tsunami source seems likely. This event is currently undated. On a note of caution however, sand and paleosol interbeds are common in the sandy coastal plains of tropical Pacific islands. Possible causes include cyclones and tsunamis, and it will therefore be necessary to establish diagnostic criteria to help distinguish between these different modes of formation. If these are palaeotsunamis then whether they relate to regional or distant events is also yet to be determined. Ultimately, more precise source identification will likely have to wait until a more comprehensive palaeotsunami dataset has been established for PICs. Mulivai - south coast of Samoa: Trench showing the 2009 South Pacific tsunami with at least two underlying sand unit and one palaeosol. Photo: C. Chagué-Goff

  5. Flame generation of two new precursors of vanadyl pyrophosphate

    SciTech Connect

    Miquel, P.F.; Katz, J.L. [Johns Hopkins Univ., Baltimore, MD (United States)] [Johns Hopkins Univ., Baltimore, MD (United States); Bordes, E. [Universite de Technologie de Compiegne (France)] [Universite de Technologie de Compiegne (France)

    1996-06-01

    Two new vanadyl pyrophosphate precursors were produced in a single step operation using a counterflow diffusion flame burner. The technique consists of adding a vanadium and a phosphorus halide to the fuel stream of hydrogen-oxygen flames. Particles nucleate and grow in the flame to an average diameter between 5 and 30 nm. Upon exiting the flame, powders are collected on two stainless steel strips and their crystalline structures are analyzed by X-ray diffraction and Fourier-transform infrared spectroscopy. A strong effect of flame temperature on the crystalline structure of the powders produced is observed. When a high temperature flame is used, the powder collected is a mixture of VOPO{sub 4} {center_dot}2H{sub 2}O and (VOPO{sub 4}){sub 1-x}(VOHOP{sub 4}){sub x}{center_dot}2.6H{sub 2}O. This mixture forms {gamma}-VOPO{sub 4} upon subsequent reheating at 750{degrees}C in a oxidizing atmosphere, and transforms into (VO){sub 2}P{sub 2}O{sub 7} in an oxygen-free atmosphere at 700{degrees}C. When a lower temperature flame is used, the powder collected is (VOPO{sub 4}){sub 1-x}(VOHPO{sub 4}){sub x}{center_dot}2.9H{sub 2}O, which transforms at 750{degrees}C into {Beta}-VOPO{sub 4} in an oxidizing atmosphere and to (VO){sub 2}P{sub 2}O{sub 7} at 700{degrees}C in an oxygen-free atmosphere. Structural differences between the two vanadyl pyrophosphates are observed. These differences are discussed in terms of the ability of (VO){sub 2}P{sub 2}O{sub 7} to accommodate various disordered and polytypic structures.

  6. Carlactone is an endogenous biosynthetic precursor for strigolactones

    PubMed Central

    Seto, Yoshiya; Sado, Aika; Asami, Kei; Hanada, Atsushi; Umehara, Mikihisa; Akiyama, Kohki; Yamaguchi, Shinjiro

    2014-01-01

    Strigolactones (SLs) are a class of terpenoid plant hormones that regulate shoot branching as well as being known as root-derived signals for symbiosis and parasitism. SL has tricyclic-lactone (ABC-ring) and methyl butenolide (D-ring), and they are connected through an enol ether bridge. Recently, a putative biosynthetic intermediate called carlactone (CL), of which carbon skeleton is in part similar to those of SLs, was identified by biochemical analysis of three biosynthetic enzymes, DWARF27, CAROTENOID CLEAVAGE DIOXYGENASE 7 (CCD7), and CCD8 in vitro. However, CL has never been identified from plant tissues, and the conversion of CL to SLs has not been proven in vivo. To address these questions, we chemically synthesized 13C-labeled CL. We show that 13C-labeled CL is converted to (?)-[13C]-2?-epi-5-deoxystrigol ((?)-2?-epi-5DS) and [13C]-orobanchol, endogenous SLs in rice, in the dwarf10 mutant, which is defective in CCD8. In addition, we successfully identified endogenous CL by using liquid chromatography-quadrupole/time-of-flight tandem mass spectrometry in rice and Arabidopsis. Furthermore, we determined the absolute stereochemistry of endogenous CL to be (11R)-configuration, which is the same as that of (?)-2?-epi-5DS at the corresponding position. Feeding experiments showed that only the (11R)-isomer of CL, but not the (11S)-isomer, was converted to (?)-2?-epi-5DS in vivo. Taken together, our data provide conclusive evidence that CL is an endogenous SL precursor that is stereospecifically recognized in the biosynthesis pathway. PMID:24434551

  7. Carlactone is an endogenous biosynthetic precursor for strigolactones.

    PubMed

    Seto, Yoshiya; Sado, Aika; Asami, Kei; Hanada, Atsushi; Umehara, Mikihisa; Akiyama, Kohki; Yamaguchi, Shinjiro

    2014-01-28

    Strigolactones (SLs) are a class of terpenoid plant hormones that regulate shoot branching as well as being known as root-derived signals for symbiosis and parasitism. SL has tricyclic-lactone (ABC-ring) and methyl butenolide (D-ring), and they are connected through an enol ether bridge. Recently, a putative biosynthetic intermediate called carlactone (CL), of which carbon skeleton is in part similar to those of SLs, was identified by biochemical analysis of three biosynthetic enzymes, DWARF27, CAROTENOID CLEAVAGE DIOXYGENASE 7 (CCD7), and CCD8 in vitro. However, CL has never been identified from plant tissues, and the conversion of CL to SLs has not been proven in vivo. To address these questions, we chemically synthesized (13)C-labeled CL. We show that (13)C-labeled CL is converted to (-)-[(13)C]-2'-epi-5-deoxystrigol ((-)-2'-epi-5DS) and [(13)C]-orobanchol, endogenous SLs in rice, in the dwarf10 mutant, which is defective in CCD8. In addition, we successfully identified endogenous CL by using liquid chromatography-quadrupole/time-of-flight tandem mass spectrometry in rice and Arabidopsis. Furthermore, we determined the absolute stereochemistry of endogenous CL to be (11R)-configuration, which is the same as that of (-)-2'-epi-5DS at the corresponding position. Feeding experiments showed that only the (11R)-isomer of CL, but not the (11S)-isomer, was converted to (-)-2'-epi-5DS in vivo. Taken together, our data provide conclusive evidence that CL is an endogenous SL precursor that is stereospecifically recognized in the biosynthesis pathway. PMID:24434551

  8. Advanced accident sequence precursor analysis level 1 models

    SciTech Connect

    Sattison, M.B.; Thatcher, T.A.; Knudsen, J.K.; Schroeder, J.A.; Siu, N.O. [Idaho National Engineering Lab., Idaho National Lab., Idaho Falls, ID (United States)

    1996-03-01

    INEL has been involved in the development of plant-specific Accident Sequence Precursor (ASP) models for the past two years. These models were developed for use with the SAPHIRE suite of PRA computer codes. They contained event tree/linked fault tree Level 1 risk models for the following initiating events: general transient, loss-of-offsite-power, steam generator tube rupture, small loss-of-coolant-accident, and anticipated transient without scram. Early in 1995 the ASP models were revised based on review comments from the NRC and an independent peer review. These models were released as Revision 1. The Office of Nuclear Regulatory Research has sponsored several projects at the INEL this fiscal year to further enhance the capabilities of the ASP models. Revision 2 models incorporates more detailed plant information into the models concerning plant response to station blackout conditions, information on battery life, and other unique features gleaned from an Office of Nuclear Reactor Regulation quick review of the Individual Plant Examination submittals. These models are currently being delivered to the NRC as they are completed. A related project is a feasibility study and model development of low power/shutdown (LP/SD) and external event extensions to the ASP models. This project will establish criteria for selection of LP/SD and external initiator operational events for analysis within the ASP program. Prototype models for each pertinent initiating event (loss of shutdown cooling, loss of inventory control, fire, flood, seismic, etc.) will be developed. A third project concerns development of enhancements to SAPHIRE. In relation to the ASP program, a new SAPHIRE module, GEM, was developed as a specific user interface for performing ASP evaluations. This module greatly simplifies the analysis process for determining the conditional core damage probability for a given combination of initiating events and equipment failures or degradations.

  9. Wildfire altering terrestrial precursors of disinfection byproducts in forest detritus.

    PubMed

    Wang, Jun-Jian; Dahlgren, Randy A; Er?an, Mahmut S; Karanfil, Tanju; Chow, Alex T

    2015-05-19

    Wildfire occurrence and intensity are increasing worldwide causing severe disturbances to forest watersheds used for potable water supply. The effects of wildfire on drinking water quality are not well understood, especially in terms of terrestrial dissolved organic matter (DOM) and DOM-associated formation of disinfection byproducts (DBP). As the forest floor layer is a major source of terrestrial DOM, we investigated characteristics and DBP formation of water extractable organic matter (WEOM) from the 0-5 cm depth of nonburned detritus (control) and burned detritus with black ash (moderate severity) and white ash (high severity) associated with the 2013 Rim Fire in California. Spectroscopic results suggested that the aromaticity of WEOM followed white ash > control > black ash and fluorescence region II (excitation 220-250 nm; emission 330-380 nm) of the emission-excitation-matrix was identified as a potential burn severity indicator. Compared to the control, WEOM from white and black ashes had lower reactivity in forming trihalomethanes (55%-of-control) and haloacetic acids (67%-of-control), but higher reactivity in forming the more carcinogenic haloacetonitrile after chlorination (244%-of-control) and N-nitrosodimethylamine after chloramination (229%-of-control). There was no change in reactivity for chloral hydrate formation, while WEOM from black ash showed a higher reactivity for haloketone formation (150%-of-control). Because wildfire consumed a large portion of organic matter from the detritus layer, there was lower water extractable organic carbon (27%-of-control) and organic nitrogen (19%-of-control) yields in ashes. Consequently, the wildfire caused an overall reduction in water extractable terrestrial DBP precursor yield from detritus materials. PMID:25894116

  10. The human ?-amyloid precursor protein: biomolecular and epigenetic aspects.

    PubMed

    Nguyen, Khue Vu

    2015-03-01

    Beta-amyloid precursor protein (APP) is a membrane-spanning protein with a large extracellular domain and a much smaller intracellular domain. APP plays a central role in Alzheimer's disease (AD) pathogenesis: APP processing generates ?-amyloid (A?) peptides, which are deposited as amyloid plaques in the brains of AD individuals; point mutations and duplications of APP are causal for a subset of early-onset familial AD (FAD) (onset age <65 years old). However, these mutations in FAD represent a very small percentage of cases (?1%). Approximately 99% of AD cases are nonfamilial and late-onset, i.e., sporadic AD (SAD) (onset age >65 years old), and the pathophysiology of this disorder is not yet fully understood. APP is an extremely complex molecule that may be functionally important in its full-length configuration, as well as the source of numerous fragments with varying effects on neural function, yet the normal function of APP remains largely unknown. This article provides an overview of our current understanding of APP, including its structure, expression patterns, proteolytic processing and putative functions. Importantly, and for the first time, my recent data concerning its epigenetic regulation, especially in alternative APP pre-mRNA splicing and in the control of genomic rearrangements of the APP gene, are also reported. These findings may provide new directions for investigating the role of APP in neuropathology associated with a deficiency in the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGprt) found in patients with Lesch-Nyhan syndrome (LNS) and its attenuated variants (LNVs). Also, these findings may be of significance for research in neurodevelopmental and neurodegenerative disorders in which the APP gene is involved in the pathogenesis of diseases such as autism, fragile X syndrome (FXS) and AD, with its diversity and complexity, SAD in particular. Accurate quantification of various APP-mRNA isoforms in brain tissues is needed, and antisense drugs are potential treatments. PMID:25719338

  11. Effects of sleep and wake on oligodendrocytes and their precursors.

    PubMed

    Bellesi, Michele; Pfister-Genskow, Martha; Maret, Stephanie; Keles, Sunduz; Tononi, Giulio; Cirelli, Chiara

    2013-09-01

    Previous studies of differential gene expression in sleep and wake pooled transcripts from all brain cells and showed that several genes expressed at higher levels during sleep are involved in the synthesis/maintenance of membranes in general and of myelin in particular, a surprising finding given the reported slow turnover of many myelin components. Other studies showed that oligodendrocyte precursor cells (OPCs) are responsible for the formation of new myelin in both the injured and the normal adult brain, and that glutamate released from neurons, via neuron-OPC synapses, can inhibit OPC proliferation and affect their differentiation into myelin-forming oligodendrocytes. Because glutamatergic transmission is higher in wake than in sleep, we asked whether sleep and wake can affect oligodendrocytes and OPCs. Using the translating ribosome affinity purification technology combined with microarray analysis in mice, we obtained a genome-wide profiling of oligodendrocytes after sleep, spontaneous wake, and forced wake (acute sleep deprivation). We found that hundreds of transcripts being translated in oligodendrocytes are differentially expressed in sleep and wake: genes involved in phospholipid synthesis and myelination or promoting OPC proliferation are transcribed preferentially during sleep, while genes implicated in apoptosis, cellular stress response, and OPC differentiation are enriched in wake. We then confirmed through BrdU and other experiments that OPC proliferation doubles during sleep and positively correlates with time spent in REM sleep, whereas OPC differentiation is higher during wake. Thus, OPC proliferation and differentiation are not perfectly matched at any given circadian time but preferentially occur during sleep and wake, respectively. PMID:24005282

  12. Alteration of synaptic connectivity of oligodendrocyte precursor cells following demyelination

    PubMed Central

    Sahel, Aurélia; Ortiz, Fernando C.; Kerninon, Christophe; Maldonado, Paloma P.; Angulo, María Cecilia; Nait-Oumesmar, Brahim

    2015-01-01

    Oligodendrocyte precursor cells (OPCs) are a major source of remyelinating oligodendrocytes in demyelinating diseases such as Multiple Sclerosis (MS). While OPCs are innervated by unmyelinated axons in the normal brain, the fate of such synaptic contacts after demyelination is still unclear. By combining electrophysiology and immunostainings in different transgenic mice expressing fluorescent reporters, we studied the synaptic innervation of OPCs in the model of lysolecithin (LPC)-induced demyelination of corpus callosum. Synaptic innervation of reactivated OPCs in the lesion was revealed by the presence of AMPA receptor-mediated synaptic currents, VGluT1+ axon-OPC contacts in 3D confocal reconstructions and synaptic junctions observed by electron microscopy. Moreover, 3D confocal reconstructions of VGluT1 and NG2 immunolabeling showed the existence of glutamatergic axon-OPC contacts in post-mortem MS lesions. Interestingly, patch-clamp recordings in LPC-induced lesions demonstrated a drastic decrease in spontaneous synaptic activity of OPCs early after demyelination that was not caused by an impaired conduction of compound action potentials. A reduction in synaptic connectivity was confirmed by the lack of VGluT1+ axon-OPC contacts in virtually all rapidly proliferating OPCs stained with EdU (50-ethynyl-20-deoxyuridine). At the end of the massive proliferation phase in lesions, the proportion of innervated OPCs rapidly recovers, although the frequency of spontaneous synaptic currents did not reach control levels. In conclusion, our results demonstrate that newly-generated OPCs do not receive synaptic inputs during their active proliferation after demyelination, but gain synapses during the remyelination process. Hence, glutamatergic synaptic inputs may contribute to inhibit OPC proliferation and might have a physiopathological relevance in demyelinating disorders. PMID:25852473

  13. ROR1 is expressed on hematogones (non-neoplastic human B-lymphocyte precursors) and a minority of precursor-B acute lymphoblastic leukemia.

    PubMed

    Broome, H Elizabeth; Rassenti, Laura Z; Wang, Huan-You; Meyer, Lilly M; Kipps, Thomas J

    2011-10-01

    ROR1 is a receptor tyrosine kinase expressed during embryogenesis, on chronic lymphocytic leukemia (CLL) and in other malignancies. Hematogones (non-neoplastic B-lymphocyte precursors) express surface ROR1 at an intermediate stage of maturation that lacks CD34 or TdT. The neoplastic counterpart to hematogones is precursor-B acute lymphoblastic leukemia (B-ALL), but less than 10% of B-ALL express surface ROR1, and these ROR1+ B-ALL cases have an unusually high frequency of lacking CD34 and/or having t(1;19), a chromosomal translocation that defines a specific subtype of B-ALL. PMID:21813176

  14. Chemical vapor deposition of Pd/Cu alloy films from a new single source precursor

    NASA Astrophysics Data System (ADS)

    Krisyuk, Vladislav V.; Shubin, Yuriy V.; Senocq, François; Turgambaeva, Asiya E.; Duguet, Thomas; Igumenov, Igor K.; Vahlas, Constantin

    2015-03-01

    Cu/Pd alloys were deposited onto Si(100) and SiO2 (fused silica) substrates by MOCVD from PdL2×CuL2, (L=2-methoxy-2,6,6-trimethylheptane-3,5-dionate), a new single source bimetallic precursor. Deposition was performed at 10 Torr in a temperature range between 200 °C and 350 °C and was assisted by vacuum ultraviolet (VUV) irradiation of the precursor vapor from an excimer Xe-lamp. It was shown that the elemental and phase composition of the films can be controlled by varying the deposition temperature and by stimulating by VUV the precursor decomposition. The bulk compositional properties of the obtained films confirmed the feasibility of proposed approach and precursor to prepare Pd alloy membrane materials by the CVD method.

  15. Atomically dispersed rhodium on a support: the influence of a metal precursor and a support.

    PubMed

    Duarte, R B; Safonova, O V; Krumeich, F; van Bokhoven, J A

    2014-12-28

    The influence of the support type and the metal precursor on the dispersion of rhodium after calcination and reduction was determined. The combination of electron microscopy and X-ray absorption analysis allowed the quantification of the amount of atomically dispersed rhodium in the samples. Higher amounts of atomically dispersed rhodium atoms are obtained when metal impregnation is performed with a rhodium acetate precursor in comparison to a rhodium chloride precursor over supports of the same composition. The stability of rhodium is improved with the addition of promoters; the co-presence of samaria and ceria in the support and metal impregnation with a rhodium acetate precursor leads to the highest amount of atomically dispersed rhodium remaining after reductive treatment at 773 K. PMID:25070506

  16. Differential Processing of Amyloid-Precursor Protein Directs Human Embryonic Stem Cell Proliferation and

    E-print Network

    Wisconsin at Madison, University of

    suppressed hESC proliferation and promoted nestin expression, an early marker of neural precursor cell (NPC functions, including neuritogenesis, synaptogenesis, and synaptic plasticity (2). The function of A PP

  17. A chlorine precursor route (CPR) to poly(p-phenylene vinylene) light emitting diodes

    SciTech Connect

    Heieh, B.R.; Antoniadis, H. [Xerox Corp., Webster, NY (United States); [Univ. of Rochester, NY (United States); Bland, D.C. [Wright State Univ., Dayton, OH (United States)] [and others

    1995-12-01

    We use a chlorine precursor route (CPR) to fabricate PPV based electroluminescent (EL) devices. 1,4- Bis(chloromethyl)-2,3-diphenylbenzene was polymerized with one equivalent amount of potassium t-butoxide (t-BuOK) to give the corresponding chlorine precursor polymer with very high molecular weights. This polymer is soluble in common organic solvents and is highly stable in the solid state and in solution. Thin films of the precursor polymer were spin cast on indiumtin-oxide (ITO) coated glass substrates followed by thermal conversion at 300{degrees}C for 2 h to give DP-PPV thin films. We found that CPR is more convenient and reliable than sulfonium precursor route for the fabrication of PPV thin film EL devices. Efficient emission of green light (500 nm) was observed for Mg/DP-PPV/ITO and Al/DP-PPV/ITO single layer devices.

  18. Expanding the Repertoire of Amyloid Polymorphs by Co-polymerization of Related Protein Precursors

    E-print Network

    Sarell, Claire J.

    Amyloid fibrils can be generated from proteins with diverse sequences and folds. Although amyloid fibrils assembled in vitro commonly involve a single protein precursor, fibrils formed in vivo can contain more than one ...

  19. Facile fabrication of carbon spheres with tunable morphologies from novel polymeric carbon precursors.

    PubMed

    Sun, Wei; Chen, Min; Zhou, Shuxue; Wu, Limin

    2014-10-14

    This study presents a facile and general method for fabrication of carbon spheres with tunable morphologies based on the sol-gel reaction of a novel polymeric carbon precursor. The carbon precursor was fabricated by the synthesis of resole, a low-molecular weight polymer of phenol and formaldehyde, and then the modification with poly(ethylene glycol) monomethyl ether (PEG). By turning the modification degree of resole with different amounts of PEG and the hydrolysis and condensation reactions of this precursor, carbon spheres with various morphologies, including regular spheres, hollow spheres of different pore sizes, and raspberry- and peanut-like spheres, were produced easily. This should be attributed to the condensation, self-assembly, and phase separation of the new polymeric carbon precursors during the sol-gel process. PMID:25267090

  20. Highly Selective In Vivo Labeling of Subcutaneous White Adipocyte Precursors with Prx1-Cre

    PubMed Central

    Sanchez-Gurmaches, Joan; Hsiao, Wen-Yu; Guertin, David A.

    2015-01-01

    Summary The origins of individual fat depots are not well understood, and thus, the availability of tools useful for studying depot-specific adipose tissue development and function is limited. Cre drivers that selectively target only brown adipocyte, subcutaneous white adipocyte, or visceral white adipocyte precursors would have significant value because they could be used to selectively study individual depots without impacting the adipocyte precursors or intrinsic metabolic properties of the other depots. Here, we show that the majority of the precursor and mature subcutaneous white adipocytes in adult C57Bl/6 mice are labeled by Prx1-Cre. In sharp contrast, few to no brown adipocytes or visceral white adipocytes are marked by Prx1-Cre. This suggests that Prx1-Cre-mediated recombination may be useful for making depot-restricted genetic manipulations in subcutaneous white adipocyte precursor cells, particularly when targeting genes with fat-specific functions. PMID:25801508

  1. A second cytotoxic proteolytic peptide derived from amyloid beta-protein precursor.

    PubMed

    Lu, D C; Rabizadeh, S; Chandra, S; Shayya, R F; Ellerby, L M; Ye, X; Salvesen, G S; Koo, E H; Bredesen, D E

    2000-04-01

    The amyloid beta-protein precursor gives rise to the amyloid beta-protein, the principal constituent of senile plaques and a cytotoxic fragment involved in the pathogenesis of Alzheimer disease. Here we show that amyloid beta-protein precursor was proteolytically cleaved by caspases in the C terminus to generate a second unrelated peptide, called C31. The resultant C31 peptide was a potent inducer of apoptosis. Both caspase-cleaved amyloid beta-protein precursor and activated caspase-9 were present in brains of Alzheimer disease patients but not in control brains. These findings indicate the possibility that caspase cleavage of amyloid beta-protein precursor with the generation of C31 may be involved in the neuronal death associated with Alzheimer disease. PMID:10742146

  2. Solution-mediated strategies for synthesizing metal oxides, borates and phosphides using nanocrystals as reactive precursors 

    E-print Network

    Henkes, Amanda Erin

    2009-05-15

    ) the solution-mediated diffusion of phosphorus into a nanocrystalline metal to form target metal phosphides. To form multi-metal oxides using the first strategy, metal oxide nanoparticle precursors are mixed in stoichiometric ratios in solution to form a...

  3. Growth characteristics of graphene synthesized via chemical vapor deposition using carbon tetrabromide precursor

    NASA Astrophysics Data System (ADS)

    Choi, Taejin; Jung, Hanearl; Lee, Chang Wan; Mun, Ki-Yeung; Kim, Soo-Hyun; Park, Jusang; Kim, Hyungjun

    2015-07-01

    A carbon tetrabromide (CBr4) precursor was employed for the chemical vapor deposition (CVD) of graphene, and the graphene growth characteristics as functions of the following key factors were then investigated: growth time, growth temperature, and the partial pressure of the precursor. The graphene was transferred onto a SiO2/Si substrate and characterized using transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy, and the electrical properties were measured through the fabrication of field-effect transistors. Our results show that high yield and controllable growth are possible via CVD used with a CBr4 precursor. Thus, CBr4 precursor is a new alternative candidate for use in the mass production of graphene.

  4. Tuning the synthesis of ternary lead chalcogenide quantum dots by balancing precursor reactivity.

    PubMed

    Smith, Danielle K; Luther, Joseph M; Semonin, Octavi E; Nozik, Arthur J; Beard, Matthew C

    2011-01-25

    We report the synthesis and characterization of composition-tunable ternary lead chalcogenide alloys PbSe(x)Te(1-x), PbS(x)Te(1-x), and PbS(x)Se(1-x). This work explores the relative reaction rates of chalcogenide precursors to produce alloyed quantum dots (QDs), and we find the highly reactive bis(trimethylsilyl) (TMS(2))-based precursors allow for the homogeneous incorporation of anions. By varying the Pb to oleic acid ratio, we demonstrate size control of similar composition alloys. We find the resulting QDs are Pb-rich but the Pb/anion ratio is size- and composition-dependent in all alloyed QD as well as in PbSe, PbTe, and PbS QDs and is consistent with the reaction rates of the anion precursors. A more reactive anion precursor results in a lower Pb/anion ratio. PMID:21141910

  5. Highly selective in vivo labeling of subcutaneous white adipocyte precursors with Prx1-Cre.

    PubMed

    Sanchez-Gurmaches, Joan; Hsiao, Wen-Yu; Guertin, David A

    2015-04-14

    The origins of individual fat depots are not well understood, and thus, the availability of tools useful for studying depot-specific adipose tissue development and function is limited. Cre drivers that selectively target only brown adipocyte, subcutaneous white adipocyte, or visceral white adipocyte precursors would have significant value because they could be used to selectively study individual depots without impacting the adipocyte precursors or intrinsic metabolic properties of the other depots. Here, we show that the majority of the precursor and mature subcutaneous white adipocytes in adult C57Bl/6 mice are labeled by Prx1-Cre. In sharp contrast, few to no brown adipocytes or visceral white adipocytes are marked by Prx1-Cre. This suggests that Prx1-Cre-mediated recombination may be useful for making depot-restricted genetic manipulations in subcutaneous white adipocyte precursor cells, particularly when targeting genes with fat-specific functions. PMID:25801508

  6. Alignment and structural control of nitrogen-doped carbon nanotubes by utilizing precursor concentration effect.

    PubMed

    Deng, Weina; Chen, Xiaohua; Chen, Xian; Liu, Zheng; Zeng, Ying; Hu, Aiping; Xiong, Yina; Li, Zhe; Tang, Qunli

    2014-11-28

    Nitrogen-doped carbon nanotubes (NCNTs) were prepared using a simple ultrasonic spray pyrolysis method. The precursor concentration effect was examined to effectively control alignment, open tip and diameter of the NCNTs by changing xylene/cyclohexylamine ratio. The structure and morphology of the resultant NCNTs were characterized by scanning electron microscopy, transmission electron microscopy and x-ray photoelectron spectroscopy. The degree of alignment and the diameter of the NCNTs increased as the xylene/cyclohexylamine precursor mixture was changed from 0 to 35% cyclohexylamine. This precursor composition also caused a large number of open-ended nanotubes to form with graphite layers inside the cavities of the NCNTs. However, further increase cyclohexylamine content in the precursor reduced the degree of alignment and diameter of the NCNTs. We demonstrate control over the NCNT alignment and diameter, along with the formation of open-ended nanotube tips, and propose a growth mechanism to understand how these properties are interlinked. PMID:25369800

  7. Alignment and structural control of nitrogen-doped carbon nanotubes by utilizing precursor concentration effect

    NASA Astrophysics Data System (ADS)

    Deng, Weina; Chen, Xiaohua; Chen, Xian; Liu, Zheng; Zeng, Ying; Hu, Aiping; Xiong, Yina; Li, Zhe; Tang, Qunli

    2014-11-01

    Nitrogen-doped carbon nanotubes (NCNTs) were prepared using a simple ultrasonic spray pyrolysis method. The precursor concentration effect was examined to effectively control alignment, open tip and diameter of the NCNTs by changing xylene/cyclohexylamine ratio. The structure and morphology of the resultant NCNTs were characterized by scanning electron microscopy, transmission electron microscopy and x-ray photoelectron spectroscopy. The degree of alignment and the diameter of the NCNTs increased as the xylene/cyclohexylamine precursor mixture was changed from 0 to 35% cyclohexylamine. This precursor composition also caused a large number of open-ended nanotubes to form with graphite layers inside the cavities of the NCNTs. However, further increase cyclohexylamine content in the precursor reduced the degree of alignment and diameter of the NCNTs. We demonstrate control over the NCNT alignment and diameter, along with the formation of open-ended nanotube tips, and propose a growth mechanism to understand how these properties are interlinked.

  8. Precursors to potential severe core damage accidents. A status report, 1982--1983

    SciTech Connect

    Forester, J.A.; Mitchell, D.B.; Whitehead, D.W. [and others] [and others

    1997-04-01

    This study is a continuation of earlier work that evaluated 1969-1981 and 1984-1994 events affecting commercial light-water reactors. One-hundred nine operational events that affected 51 reactors during 1982 and 1983 and that are considered to be precursors to potential severe core damage are described. All these events had conditional probabilities of subsequent severe core damage greater than or equal to 1.0 x 10{sup {minus}6}. These events were identified by first computer screening the 1982-83 licensee event reports from commercial light-water reactors to select events that could be precursors to core damage. Candidates underwent engineering evaluation that identified, analyzed, and documented the precursors. This report discusses the general rationale for the study, the selection and documentation of events as precursors, and the estimation of conditional probabilities of subsequent severe core damage for the events.

  9. Structural and Functional Studies of Mycothiol Biosynthesis Precursor Enzyme in Mycobacterium tuberculosis 

    E-print Network

    Zhu, Wan Wen

    2012-10-19

    MshA is a glycosyltransferase that synthesizes the precursor of mycothiol, a low-molecular-weight thiol found exclusively in Actinomycetes, including the virulent pathogen Mycobacterium tuberculosis (Mtb). The structure of MshA from Mtb (herein...

  10. Recovery of gibberellic acid inhibition of betacyanin biosynthesis by pigment precursors

    Microsoft Academic Search

    M. M. Laloraya; H. N. Srivastav; K. N. Guruprasad

    1976-01-01

    Gibberellic acid inhibition of betacyanin biosynthesis has been studied in Amaranthus caudatus L. using the pigment precursors L-tyrosine and L-dihydroxyphenylalanine. Precursors fed to gibberellic acid (GA) treated seedlings completely recovered betacyanin synthesis while the GA induced growth enhancement remained unaltered. Inhibition of betacyanin biosynthesis by GA is related to depletion of metabolites\\/amino acids and their diversion to support changed pattern

  11. Utilization of alpha-ketoglutarate as a precursor for transmitter glutamate in cultured cerebellar granule cells

    Microsoft Academic Search

    Liang Peng; Arne Schousboe; Leif Hertz

    1991-01-01

    Alpha-ketoglutarate together with an amino group donor (alanine) was shown to be able to serve as a precursor for the glutamate pool which is released by potassium-induced depolarization (i.e., transmitter glutamate) in cerebellar granule cells. However, these compounds could not be utilized as precursors for intracellular glutamate or for release of transmitter aspartate. The formation of transmitter glutamate was inhibited

  12. Ion-precursor and ion-dose dependent anti-galvanic reduction.

    PubMed

    Tian, Shubo; Yao, Chuanhao; Liao, Lingwen; Xia, Nan; Wu, Zhikun

    2015-07-01

    Controlling alloy nanoparticles with atomic monodispersity is challenging, and the recently revealed anti-galvanic reduction (AGR) provides a unique solution to this challenge. Herein we demonstrate that AGR is ion-precursor and ion-dose dependent, which offers novel strategies to tune the composition, structure and properties of nanoparticles by varying the ion-precursor and ion-dose in the AGR reaction. PMID:26107653

  13. Endothelial Outgrowth Cells Are Not Derived From CD133 Cells or CD45 Hematopoietic Precursors

    Microsoft Academic Search

    Frank Timmermans; Filip Van Hauwermeiren; Magda De Smedt; Robrecht Raedt; Frank Plasschaert; Marc L. De Buyzere; Thierry C. Gillebert; Jean Plum; Bart Vandekerckhove

    2010-01-01

    Objective—Two types of endothelial progenitor cells (EPCs), early EPCs and late EPCs (also called endothelial outgrowth cells (EOCs)), were described in vitro previously. In this report, we dissect the phenotype of the precursor(s) that generate these cell types with focus on the markers CD34, CD133, and vascular endothelial growth factor receptor-2 (VEGFR2) that have been used to identify putative circulating

  14. Solution-based precursors in conjunction with rapid optical processing for high-quality hybrid CIGS

    NASA Astrophysics Data System (ADS)

    Hersh, Peter A.; Curtis, Calvin J.; van Hest, Maikel F. A. M.; Habas, Susan E.; Miedaner, Alexander; Ginley, David S.; Stanbery, Billy J.

    2011-09-01

    HelioVolt Corporation is currently developing Copper Indium Gallium Selenide (CIGS) products using a solution-based deposition of precursor films followed by 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®) processing.

  15. Cobalt Ferrite from Citrate Precursor by Self-Propagating Combustion Reaction

    Microsoft Academic Search

    N. N. Mallikarjuna; A. Lagashetty; A. Venkataraman

    2003-01-01

    Cobalt ferrite was synthesised by the thermal decomposition of a citrate precursor through a novel self-propagating combustion\\u000a reaction (SPCR) and the progress of this reaction is explained. Cobalt ferrite obtained by this reaction is compared with\\u000a the products obtained by heat treatment of the citrate complex. The thermal behaviour and structures of the precursor, the\\u000a synthesised ferrite, and the other

  16. Sol–gel derived porous ceria powders using cerium glycolate complex as precursor

    Microsoft Academic Search

    Bussarin Ksapabutr; Erdogan Gulari; Sujitra Wongkasemjit

    2006-01-01

    The preparation of ceria powders via a sol–gel process using cerium glycolate complex as precursor has been investigated to study the hydrolysis and condensation of cerium glycolate precursor. The gelation was followed by FT-IR spectroscopy and the evolution of the CeOC and CeOCe bands of the cerium glycolate molecule was analyzed. The intensity of these bands decreased with the hydrolysis

  17. Oral Language and Code-Related Precursors to Reading: Evidence From a Longitudinal Structural Model

    Microsoft Academic Search

    Stacey A. Storch; Grover J. Whitehurst

    2002-01-01

    This study examined code-related and oral language precursors to reading in a longitudinal study of 626 children from preschool through 4th grade. Code-related precursors, including print concepts and phonological awareness, and oral language were assessed in preschool and kindergarten. Reading accuracy and reading comprehension skills were examined in 1st through 4th grades. Results demonstrated that (a) the relationship between code-related

  18. Synthesis of transition metal nitride by nitridation of metastable oxide precursor

    SciTech Connect

    Wang, Huamin; Wu, Zijie; Kong, Jing [Key Laboratory of Advanced Energy Materials Chemistry (MOE), College of Chemistry, Nankai University, Tianjin 300071 (China)] [Key Laboratory of Advanced Energy Materials Chemistry (MOE), College of Chemistry, Nankai University, Tianjin 300071 (China); Wang, Zhiqiang, E-mail: zqwang@mail.nankai.edu.cn [Key Laboratory of Advanced Energy Materials Chemistry (MOE), College of Chemistry, Nankai University, Tianjin 300071 (China) [Key Laboratory of Advanced Energy Materials Chemistry (MOE), College of Chemistry, Nankai University, Tianjin 300071 (China); Tianjin Key Laboratory of Water Environment and Resources, Tianjin Normal University, No. 393 Binshui Road, Xiqing Dist., Tianjin 300387 (China); Zhang, Minghui, E-mail: zhangmh@nankai.edu.cn [Key Laboratory of Advanced Energy Materials Chemistry (MOE), College of Chemistry, Nankai University, Tianjin 300071 (China)] [Key Laboratory of Advanced Energy Materials Chemistry (MOE), College of Chemistry, Nankai University, Tianjin 300071 (China)

    2012-10-15

    Metastable transition metal oxides were used as precursors to synthesize transition metal nitrides at low temperature. Amorphous MoO{sub 2} was prepared by reduction of (NH{sub 4}){sub 6}Mo{sub 7}O{sub 24} solution with hydrazine. As-synthesized amorphous MoO{sub 2} was transformed into fcc {gamma}-Mo{sub 2}N at 400 Degree-Sign C and then into hexagonal {delta}-MoN by further increasing the temperature to 600 Degree-Sign C under a NH{sub 3} flow. The nitridation temperature employed here is much lower than that employed in nitridation of crystalline materials, and the amorphous materials underwent a unique nitridation process. Besides this, the bimetallic nitride Ni{sub 2}Mo{sub 3}N was also synthesized by nitridating amorphous bimetallic precursor. These results suggested that the nitridation of amorphous precursor possessed potential to be a general method for synthesizing many interstitial metallic compounds, such as nitrides and carbides at low temperature. - graphical abstract: Amorphous oxide was used as new precursor to prepare nitride at low temperature. Pure {gamma}-Mo{sub 2}N and {delta}-MoN were obtained at 400 Degree-Sign C and at 600 Degree-Sign C, respectively. Highlights: Black-Right-Pointing-Pointer We bring out a new method to synthesize transition metal nitrides at low temperature. Black-Right-Pointing-Pointer Both mono- and bimetallic molybdenum nitrides were synthesized at a mild condition. Black-Right-Pointing-Pointer The formation of two different molybdenum nitrides {gamma}-Mo{sub 2}N and {delta}-MoN can be controlled from the same metastable precursor. Black-Right-Pointing-Pointer The nitridation temperature was much lower than that reported from crystalline precursors. Black-Right-Pointing-Pointer The metastable precursor had different reaction process in comparison with crystalline precursor.

  19. Argon-ion laser direct-write Al deposition from trialkylamine alane precursors

    Microsoft Academic Search

    F. Foulon; M. Stuke

    1993-01-01

    Laser direct writing of aluminum lines on Si, GaAs and Al2O3 substrates using the trialkylamine alane precursors, (C2H5)3N · AlH3 (TEAA) and (CH3)3N · AlH3 (TMAA), is reported. Deposition, carried out with a continuous wave Ar+ laser working at 514 nm, results from the thermal decomposition of the precursor via laser-induced surface heating at temperatures in excess of 360 K.

  20. Influence of precursors on the morphology and performance of TiO 2 photoanodes

    Microsoft Academic Search

    C. Mailhe-Randolph; A. J. McEvoy; M. Grätzel

    1991-01-01

    The preparation of TiO2 photoanodes for dye-sensitized electrochemical devices was investigated. TiO2 precursors with different rates of hydrolysis were used to modify the microstructures of the resulting TiO2 photoanodes. The photoelectrochemical quantum yield for electrodes prepared from citrate remained low. Acetate precursors gave rise to electrodes with high fill factors and high open circuit voltages. Titanium isopropoxide hydrolysed very rapidly,

  1. Interaction of the targeting sequence of chloroplast precursors with Hsp70 molecular chaperones

    Microsoft Academic Search

    Daniela V. Rial; Adrian K. Arakaki; Eduardo A. Ceccarelli

    2000-01-01

    We have analyzed the interaction of DnaK and plant Hsp70 proteins with the wild-type ferredoxin-NADP1 reductase precursor (preFNR) and mutants containing amino-acid replacements in the targeting sequence. Using an algorithm already developed (Rudiger, S., Germeroth, L., Schneider-Mergener, J. & Bukau, B. (1997) EMBO J. 16, 1501-1507) we observed that 75% of the 727 plastid precursor proteins analyzed contained at least

  2. CCMR: Pt hexafluoroacetlyacetonate as a Precursor for Pt Intermetallic Nanoparticle Synthesis

    NSDL National Science Digital Library

    Weiss, Marilyn

    2007-08-29

    This research sought to investigate a better precursor for platinum (Pt) intermetallic nanoparticles that can be utilized as anode electrocatalysts in fuel cells. The compound Pt hexafluoroacetylacetonate can be used as a Pt intermetallic precursor for making PtPb nanoparticles when using appropriate washes (methanol usage and hexane avoidance). Modifying the standard procedures for the synthesis of PtPb nanoparticle synthesis may be useful in future work where organic ligands must be avoided in order to achieve room temperature particle crystallization.

  3. Structural Analysis of Triacylglycerols by Using a MALDI-TOF/TOF System with Monoisotopic Precursor Selection

    NASA Astrophysics Data System (ADS)

    Kubo, Ayumi; Satoh, Takaya; Itoh, Yoshiyuki; Hashimoto, Masahiro; Tamura, Jun; Cody, Robert B.

    2013-05-01

    A new MALDI-TOF/TOF system with monoisotopic precursor selection was applied to the analysis of triacylglycerols in an olive oil sample. Monoisotopic precursor selection made it possible to obtain product-ion mass spectra without interference from species that differed by a single double bond. Complete structure determination of all triacylglycerols, including structural isomers, was made possible by interpreting the charge-remote fragmentation resulting from high-energy collision-induced dissociation (CID) of the sodiated triacylglycerols.

  4. Adult neurogenesis in the crayfish brain: proliferation, migration and possible origin of precursor cells

    PubMed Central

    Zhang, Y.; Allodi, S.; Sandeman, D.C.; Beltz, B.S.

    2015-01-01

    The birth of new neurons and their incorporation into functional circuits in the adult brain is a characteristic of many vertebrate and invertebrate organisms, including decapod crustaceans. Precursor cells maintaining life-long proliferation in the brains of crayfish (Procambarus clarkii, Cherax destructor) and clawed lobsters (Homarus americanus) reside within a specialized niche on the ventral surface of the brain; their daughters migrate to two proliferation zones along a stream formed by processes of the niche precursors. Here they divide again, finally producing interneurons in the olfactory pathway. The present studies in P. clarkii explore (1) differential proliferative activity among the niche precursor cells with growth and aging, (2) morphological characteristics of cells in the niche and migratory streams, and (3) aspects of the cell cycle in this lineage. Morphologically symmetrical divisions of neuronal precursor cells were observed in the niche near where the migratory streams emerge, as well as in the streams and proliferation zones. The nuclei of migrating cells elongate and undergo shape changes consistent with nucleokinetic movement. LIS1, a highly conserved dynein-binding protein, is expressed in cells in the migratory stream and neurogenic niche, implicating this protein in the translocation of crustacean brain neuronal precursor cells. Symmetrical divisions of the niche precursors and migration of both daughters raised the question of how the niche precursor pool is replenished. We present here preliminary evidence for an association between vascular cells and the niche precursors, which may relate to the life-long growth and maintenance of the crustacean neurogenic niche. PMID:19294644

  5. The effects of shock wave precursors ahead of hypersonic entry vehicles

    E-print Network

    Stanley, Scott Alan, 1965-

    1990-01-01

    THE EFFECTS OF SHOCK WAVE PRECURSORS AHEAD OF HYPERSONIC ENTRY VEHICLES A Thesis by SCOTT ALAN STANLEY Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE December 1990 Major Subject: Aerospace Engineering THE EFFECTS OF SHOCK WAVE PRECURSORS AHEAD OF HYPERSONIC ENTRY VEHICLES A Thesis by SCOTT ALAN STANLEY Approved as to style and content by: Leland A. Carlson (Chair of Committee) Walter...

  6. Amyloid Precursor Protein Binding Protein1 Modulates Cell Cycle Progression in Fetal Neural Stem Cells

    Microsoft Academic Search

    Yuyoung Joo; Sungji Ha; Bo-Hyun Hong; Jeong A. Kim; Keun-A. Chang; Hyunjeong Liew; Seonghan Kim; Woong Sun; Joung-Hun Kim; Young Hae Chong; Yoo-Hun Suh; Hye-Sun Kim; Brian Christie

    2010-01-01

    Amyloid precursor protein binding protein-1 (APP-BP1) binds to the carboxyl terminus of the amyloid precursor protein (APP) and serves as the bipartite activation enzyme for the ubiquitin-like protein, NEDD8. In the present study, we explored the physiological role of APP-BP1 in the cell cycle progression of fetal neural stem cells. Our results show that cell cycle progression of the cells

  7. Al2O3-5 wt% Al composites by ICP sintering of synthesized precursor

    Microsoft Academic Search

    S. N. Sinha; S. H. Kim

    1994-01-01

    Microstructure developments during the milling of Al2O3-5wt% Al composite powder in an attritor and subsequent sintering of the precursor by inductively coupled argon plasma are presented. After 4 h of milling the precursor contained tubular ceramic-metal and uniform ceramic regions. With an increase in the milling period the ceramic-metal regions broke into smaller and almost globular regions, and the smaller

  8. HAPs-Rx: Precombustion Removal of Hazardous Air Pollutant Precursors

    SciTech Connect

    David J. Akers; Clifford E. Raleigh

    1998-03-16

    CQ Inc. and its project team members--Howard University, PrepTech Inc., Fossil Fuel Sciences, the United States Geological Survey (USGS), and industry advisors--are applying mature coal cleaning and scientific principles to the new purpose of removing potentially hazardous air pollutants from coal. The team uniquely combines mineral processing, chemical engineering, and geochemical expertise. This project meets more than 11 goals of the U.S. Department of Energy (DOE), the National Energy Strategy, and the 1993 Climate Change Action Plan. During this project: (1) Equations were developed to predict the concentration of trace elements in as-mined and cleaned coals. These equations, which address both conventional and advanced cleaning processes, can be used to increase the removal of hazardous air pollutant precursors (HAPs) by existing cleaning plants and to improve the design of new cleaning plants. (2) A promising chemical method of removing mercury and other HAPs was developed. At bench-scale, mercury reductions of over 50 percent were achieved on coal that had already been cleaned by froth flotation. The processing cost of this technology is projected to be less than $3.00 per ton ($3.30 per tonne). (3) Projections were made of the average trace element concentration in cleaning plant solid waste streams from individual states. Average concentrations were found to be highly variable. (4) A significantly improved understanding of how trace elements occur in coal was gained, primarily through work at the USGS during the first systematic development of semiquantitative data for mode of occurrence. In addition, significant improvement was made in the laboratory protocol for mode of occurrence determination. (5) Team members developed a high-quality trace element washability database. For example, the poorest mass balance closure for the uncrushed size and washability data for mercury on all four coals is 8.44 percent and the best is 0.46 percent. This indicates an extremely high level of reproducibility of the data. In addition, a series of ''round-robin'' tests involving various laboratories was performed to assure analytical accuracy. (6) A comparison of the cost of lowering mercury emissions through the use of coal cleaning technologies versus the use of post-combustion control methods such as activated carbon injection indicates that, in many cases, coal cleaning may prove to be the lower-cost option. The most significant disadvantage for using coal cleaning for control of mercury emissions is that a reduction of 90 percent or greater from as-fired coal has not yet been demonstrated, even at laboratory-scale.

  9. [Thyroid hormones and their precursors. II. Species-specific properties].

    PubMed

    Tóth, Gergo; Noszál, Béla

    2014-01-01

    This paper surveys the species-specific physico-chemical parameters (basicity and lipophilicity) and related biological functions of thyroid hormones (thyroxine, liothyronine and reverse liothyronine) and their biological precursors (tyrosine, monoiodotyrosine and diiodotyrosine). The protonation macroconstants were determined by 1H NMR-pH titrations while the microconstants were determined by a multimodal spectroscopic-deductive methodology using auxiliary derivatives of reduced complexity. Our results show that the different number and/or position of iodine are the key factors to influence the phenolate basicity. The ionization state of the phenolate site is crucial in the biosynthesis and protein binding of thyroid hormones. The role of the protonation state in the receptor binding was investigated by an in silico docking method. Microspecies of thyroid hormones were docked to the thyroid hormone receptor isoforms. Our results quantitate at the molecular level how the ionization stage and the charge distribution influence the protein binding. The anionic form of the carboxyl group is essential for the protein binding, whereas the protonated form of the amino group loosens it. The protonation state of the phenolate plays a role of secondary importance in the receptor binding. The combined results of docking and microspeciation studies show that microspecies of the highest concentration at the pH of blood are not the strongest binding ones. The site-specific lipophilicity of our investigated molecules was determined with the measurement of distribution coefficients at different pH using carboxymethyl- and O-methyl-derivatives to mimic the partition of some of the individual microspecies. Correction factors were determined and introduced. Our data show that the iodinated aromatic ring system is the definitive structural element that fundamentally determines the lipophilicity of thyroid hormones, whereas the protonation state of the aliphatic part is essential in receptor binding. The membrane transport of thyroid hormones can be well interpreted in terms of the site-specific lipophilicity. At physiological pH these biomolecules are strongly amphipathic due to the lipophilic aromatic rings and hydrophilic amino acid side chains which can well be the reason why thyroid hormones cannot cross membranes by passive diffusion and they even become constituents of biological membranes. The site-specific physico-chemical characterization of the thyroid hormones is of fundamental importance to understand their (patho) physiological behavior and also, to influence the therapeutic properties of their drug candidate derivatives at the molecular level. PMID:24809164

  10. Air Quality Modeling of Ozone Radical Precursors in Houston

    NASA Astrophysics Data System (ADS)

    Rappenglueck, B.; Czader, B.; Li, X.

    2013-05-01

    The Houston-Galveston area has one of the highest ozone concentrations in the U.S., often exceeding the U.S. National Ambient Air Quality Standard for ozone. Photochemical modeling of ozone formation in the Houston area generally underestimates the concentrations of free radical precursors contributing to ozone formation. Here we present modeling results using the Weather Research Forecast - Community Multiscale Air Quality (WRF-CMAQ) modeling system for the Houston-Galveston area. Meteorological parameters predicted by WRF are well simulated most of the time, including planetary boundary layer heights. Air quality simulations for the Houston-Galveston-Brazoria area using the combined WRF-SMOKE-CMAQ system showed overall good results for ozone and many other trace gases. HONO morning peaks are no longer underpredicted, on some occasions they are slightly overpredicted, which can be linked to NO2 overprediction. However, CMAQ mispredicts other trace gases like HO2, H2O2 and CH3OOH concentrations. The WRF-SMOKE-CMAQ system was also used to elucidate the relative importance of various photolysis processes as radical sources in the Houston atmosphere. Morning HOx formation is dominated by HONO while ozone contributes the most during midday. HONO contribution to HOx formation is more pronounced at the surface layer where most of it is formed. On the other hand, radical production from ozone is more important at elevated levels where higher concentrations of ozone are observed. Formaldehyde contributes up to 40% and also peaks during mid-day, but on days when high morning concentrations of formaldehyde are observed its contribution to HOx in the morning exceeds that of ozone. Photolysis of H2O2 is a minor contributor to radical levels. The process analysis tool available in CMAQ was utilized to analyze photochemical processes leading to ozone production and chemical transformations along trajectories linking a site at the Houston Ship Channel and the University of Houston Moody Tower site. In particular, observations often showed elevated HCHO mixing ratios at the Moody Tower under these conditions during morning hours. UH performed additional simulations focusing on these high HCHO peaks. While additional ethene and OLE 1 emissions were added to match the corresponding observations at the Moody Tower, these additions were only able to produce small additions to the HCHO peak.

  11. Measurements of Ozone Precursors in the Lake Tahoe Basin, USA

    NASA Astrophysics Data System (ADS)

    Zielinska, B.; Bytnerowicz, A.; Gertler, A.; McDaniel, M.; Rayne, S.; Burley, J. D.

    2014-12-01

    Lake Tahoe, located at 6,225 ft. (1,897 m) in the Sierra Nevada mountain range, is the largest alpine lake in North America. Known for the clarity of its water and the panorama of surrounding mountains on all sides, Lake Tahoe is a prime tourist attraction in the California - Nevada area. However, the Lake Tahoe Basin is facing significant environmental pollution problems, including declining water clarity and air quality issues. During the period of July 21 - 26, 2012, we conducted a field study in the Basin designed to characterize the precursors and pathways of secondary pollutant formation, including ozone and secondary organic aerosol (SOA). Four sites were selected; two were located at high elevations (one each on the western and eastern sides of the Basin) and two were positioned near the Lake level. Ozone and NO/NO2 concentrations were continuously measured. With a resolution of several hours over a 6-day sampling period canister samples were collected for detailed speciation of volatile organic compounds (VOC), 2,4-dinitrophenylhydrazine (DNPH) impregnated Sep-Pak cartridges for analysis of carbonyl compounds, PM2.5 Teflon and quartz filter samples for determination of mass, organic and elemental carbon (OC/EC) concentrations and speciation of organic compounds. Whereas the concentrations of lower molecular weight (mw) C2 - C3 hydrocarbons were generally the highest at all sampling sites, ranging from 25 to 76% of the total measured VOC (over 70 species from C2 to C10), the concentrations of biogenic hydrocarbons, isoprene and ?-pinene were significant, ranging from 1.4 to 26% and 1.5 to 30%, respectively, of the total VOC. For comparison, the sum of benzene, toluene, ethylbenzene and xylenes (BTEX) constituted from 2.5 to 37% of the total VOC. All four sites showed maximum ozone concentrations in the range of 60 ppb. However, the lower sites show a pronounced diurnal pattern (i.e. maximum concentrations during the daytime hours, 0900 to 1700, with minimum values at night and in the early morning hours), whereas the upper sites shows much less variability over the 24-hour diurnal period. NO/NO2 concentrations were generally low, in the range of a few ppb. This presentation will discuss VOC and NOx patterns at these four sites in terms of their relevance to local ozone formation and/or regional transport.

  12. Afterglows from precursors in gamma-ray bursts. Application to the optical afterglow of GRB 091024

    NASA Astrophysics Data System (ADS)

    Nappo, F.; Ghisellini, G.; Ghirlanda, G.; Melandri, A.; Nava, L.; Burlon, D.

    2014-12-01

    About 15 per cent of gamma-ray bursts have precursors, i.e. emission episodes preceding the main event, whose spectral and temporal properties are similar to the main emission. We propose that precursors have their own fireball, producing afterglow emission due to the dissipation of the kinetic energy via external shock. In the time lapse between the precursor and the main event, we assume that the central engine is not completely turned off, but it continues to eject relativistic material at a smaller rate, whose emission is below the background level. The precursor fireball generates a first afterglow by the interaction with the external circumburst medium. Matter injected by the central engine during the `quasi-quiescent' phase replenishes the external medium with material in relativistic motion. The fireball corresponding to the main prompt emission episode rams into this moving material, producing a second afterglow, and finally catches up and merges with the first precursor fireball. We test this scenario over GRB 091024, an event with a precursor in the prompt light curve and two well-defined bumps in the optical afterglow, obtaining an excellent agreement with the existing data.

  13. Cd–cysteine precursor nanowire templated microwave-assisted transformation route to CdS nanotubes

    SciTech Connect

    Liu, Xiao-Lin, E-mail: liu_x_l@sina.cn [School of Material Science and Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 (China)] [School of Material Science and Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 (China); Zhu, Ying-Jie [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)] [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhang, Qian; Li, Zhi-Feng; Yang, Bin [School of Material Science and Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 (China)] [School of Material Science and Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 (China)

    2012-12-15

    Graphical abstract: Cadmium sulfide polycrystalline nanotubes have been successfully synthesized by microwave-assisted transformation method using Cd–cysteine precursor nanowires as the source material and template in ethylene glycol at 160 °C or ethanol at 60 °C. Display Omitted Highlights: ? Cd–cysteine precursor nanowires were successfully synthesized in alkaline solution. ? CdS nanotubes were prepared by templated microwave-assisted transformation method. ? CdS nanotubes can well duplicate the size and morphology of precursor nanowires. ? This method has the advantages of the simplicity and low cost. -- Abstract: We report the Cd–cysteine precursor nanowire templated microwave-assisted transformation route to CdS nanotubes. In this method, the Cd–cysteine precursor nanowires are synthesized using CdCl{sub 2}·2.5H{sub 2}O, L-cysteine and ethanolamine in water at room temperature. The Cd–cysteine precursor nanowires are used as the source material and template for the subsequent preparation of CdS nanotubes by a microwave-assisted transformation method using ethylene glycol or ethanol as the solvent. This method has the advantages of the simplicity and low cost, and may be extended to the synthesis of nanotubes of other compounds. The products are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

  14. Thymic influence on the T-lymphocyte self MHC repertoire. I. Helper T-lymphocyte precursors.

    PubMed

    Jenski, L J; Belloni, M L; Miller, B A

    1988-01-01

    We measured the frequencies of helper T-cell precursors in spleens of allogeneic thymus-grafted nude mice to determine whether allogeneic thymus engraftment resulted in clonal deletion of helper T-cells reactive to thymic major histocompatibility complex alloantigens, thereby producing tolerance to the thymic alloantigens. C3H thymus-grafted nudes had nearly normal numbers of C3H-reactive helper T-cell precursors, whereas C57BL/6 thymus-grafted nudes had significantly reduced numbers of C57BL/6-reactive helper T-cell precursors. Additional evidence suggested that tolerance was not due to a paucity of helper T-cell precursors: a) there was no correlation between the helper T-cell precursor frequency and the ability to mount cytotoxic responses against the thymic alloantigens, and b) exogenous helper factors did not break cytotoxic T-lymphocyte tolerance to thymic alloantigens. Thus, we conclude that immune tolerance resulting from engraftment of allogeneic thymic tissue is not necessarily due to clonal deletion of specific helper T-cell precursors. PMID:2966463

  15. Advances in the design of heavy alkaline earth metal complexes as precursors for chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    O'Brien, Anna Yosick

    The heavy alkaline earth metals, calcium, strontium, and barium, are components in thin films with electronic properties such as high-capacitance, superconductance and electroluminescence. The formation of these thin films by chemical vapor deposition (CVD) methods requires precursors that are volatile, but the high reactivity of the heavy alkaline earth metal precursors has made this challenging. Historically, heavy alkaline earth metal beta-diketonates have been utilized as precursors, but their tendency towards aggregation and hydrolysis affords high molecular weight compounds with low volatility. The lack of a suitable heavy alkaline earth metal precursor is a major limiting factor in the production of these electronic thin films by CVD. As a result, improved precursor materials have been pursued, yet a number of drawbacks, including limited synthetic methodologies, lack of availability, and incorporation of undesired elements into the films, have prevented their widespread use in industry. This thesis work focuses on the development of novel alkaline earth metal precursors based on pyrazolate and beta-ketoiminate ligand systems, which are thermally robust, readily available, and devoid of undesired elements such as silicon and fluorine. One of the key factors in precursor design is control of the coordination environment of the metal, to prevent aggregation and hydrolysis, and to keep the volatility high. However, the coordination chemistry of the heavy alkaline earth metals is only in its infancy, which is a major roadblock in the design of future precursors. Concurrently with the development of new precursors, this thesis work uncovers new insights into their coordination chemistry, most significantly, the effects of agostic interactions on the thermal stability of the compounds. Secondary interactions, such as agostics and pi-bonding, appear to play a large role in the coordination chemistry of these metals, with implications in the design of future precursors. Additional findings in this work reveal the reproducible formation of an alkaline earth metal-hydroxide framework with triply bridging pyrazolate ligands in novel binding modes. Furthermore, the effect of synthetic methodologies on a beta-ketoiminate ligand system is presented, specifically, the use of direct metallation by ammonia activation.

  16. Pitch-based activated carbon fibers: The effect of precursor composition on pore structure

    NASA Astrophysics Data System (ADS)

    Tekinalp, Halil Levent

    Although researchers have previously investigated the effect of precursor differences on the final properties of activated carbon fibers (ACFs), those precursors were not well-characterized. In particular, detailed information about their molecular composition and anisotropy was not available. In this study, seven oligomeric fractions, each of well-defined composition and molecular weight (mol wt) distribution, were isolated from a commercially produced isotropic petroleum pitch (i.e., Marathon M-50) and used for the production of ACFs. Four of these precursors of varying oligomeric composition were fully isotropic and three contained different levels of mesophase, so that the effects of molecular composition and molecular order were successfully isolated from each other. After the precursors were melt-spun into fibers and stabilized, they were processed by so-called "direct activation", whereby carbonization and activation occurred simultaneously. Separate carbonization tests were also carried out in order to separate out the effects of carbonization vs. activation. Carbonization weight loss was found to be higher for fibers prepared from lower average mol wt (480--550 Da) precursors. The presence of mesophase per se did not affect weight loss during carbonization. On the other hand, activation weight loss (˜28 percent) was found to be essentially independent of precursor mol wt for all isotropic fibers. (Activation weight loss for mesophase-containing fibers was much lower.) The micropore volume of the ACFs was found to increase with decreasing precursor mol wt. However, the ratio of pores smaller than 7 A (i.e., the desired pore size for hydrogen storage) to the total pore volume (3.9--30 A) was found to be essentially constant for all isotropic precursors, suggesting that a similar activation mechanism occurred for all of these materials, with both new pore formation and pore widening proceeding at similar rates. For mesophase-containing precursors, on the other hand, this pore volume ratio significantly decreased with increasing mesophase content, indicating that pore widening dominates over new pore formation for this morphology. In conclusion, this study showed that the lowest mol wt precursor (i.e., a 99 percent dimer cut with a mol wt of 480 Da) attained the highest narrow micropore (?7 A) volume required for hydrogen storage.

  17. A thermal and chemical degradation approach to decipher pristane and phytane precursors in sedimentary organic matter

    USGS Publications Warehouse

    Koopmans, M.P.; Rijpstra, W.I.C.; Klapwijk, M.M.; De Leeuw, J. W.; Lewan, M.D.; Sinninghe, Damste J.S.

    1999-01-01

    A thermal and chemical degradation approach was followed to determine the precursors of pristane (Pr) and phytane (Ph) in samples from the Gessoso-solfifera, Ghareb and Green River Formations. Hydrous pyrolysis of these samples yields large amounts of Pr and Ph carbon skeletons, indicating that their precursors are predominantly sequestered in high-molecular-weight fractions. However, chemical degradation of the polar fraction and the kerogen of the unheated samples generally does not release large amounts of Pr and Ph. Additional information on the precursors of Pr and Ph is obtained from flash pyrolysis analyses of kerogens and residues after hydrous pyrolysis and after chemical degradation. Multiple precursors for Pr and Ph are recognised in these three samples. The main increase of the Pr/Ph ratio with increasing maturation temperature, which is associated with strongly increasing amounts of Pr and Ph, is probably due to the higher amount of precursors of Pr compared to Ph, and not to the different timing of generation of Pr and Ph.A thermal and chemical degradation approach was followed to determine the precursors of pristane (Pr) and phytane (Ph) in samples from the Gessoso-solfifera, Ghareb and Green River Formations. Hydrous pyrolysis of these samples yields large amounts of Pr and Ph carbon skeletons, indicating that their precursors are predominantly sequestered in high-molecular-weight fractions. However, chemical degradation of the polar fraction and the kerogen of the unheated samples generally does not release large amounts of Pr and Ph. Additional information on the precursors of Pr and Ph is obtained from flash pyrolysis analyses of kerogens and residues after hydrous pyrolysis and after chemical degradation. Multiple precursors for Pr and Ph are recognised in these three samples. The main increase of the Pr/Ph ratio with increasing maturation temperature, which is associated with strongly increasing amounts of Pr and Ph, is probably due to the higher amount of precursors of Pr compared to Ph, and not to the different timing of generation of Pr and Ph.

  18. Theoretical model of CR Forbush-decrease and precursors effects

    NASA Astrophysics Data System (ADS)

    Lev, Dorman

    The understanding of the mechanism of CR Forbush decrease and precursor effects is important for forecasting of the great magnetic storms by using on-line one hour CR observation data. We consider in details the situation with CR distribution inside CME and how it changed with time. We suppose that shock wave before CME is semi-transpired and the coefficient of transparence depends from the CR particles rigidity. One differential equation determined the change of CR intensity inside CME by the particle energy decrease in the expanding volume and by exchange with CR particles outside the CME. The other differential equation determined the outside CR particles drift acceleration by interaction with the shock wave before CME (this effect gives increase of CR intensity before magnetic storm sudden commencement) as well as exchange with CR particles inside the CME along the IMF lines (what gives the decrease of CR intensity before the start of magnetic storm on the Earth). We calculate also the expected CR anisotropy. Obtained results we compare with observation data. It is obvious now that according to data from the past on big variations of planetary surface temperature on scales of many millions and thousands of years, the Earth’s global climate change is determined mostly by space factors, including: the moving of the Solar system around the center of our galaxy, the crossing of galactic arms and molecular dust clouds, nearby supernova and supernova remnants. Another important space factor is the cyclic variations of solar activity and the solar wind (mostly on the scale of hundreds of years and decades). The effects of space factors on the Earth’s climate are realized mostly through cosmic rays (CR) and space dust influencing the formation of clouds, thereby controlling the total energy input from the Sun into the Earth’s atmosphere. The propagation and modulation of galactic CR (generated mostly during supernova explosions and in supernova remnants in our galaxy) in the heliosphere are determined by their interactions with magnetic fields frozen in the solar wind and in coronal mass ejections (CME), which are accompanied by interplanetary shock waves (producing big magnetic storms during their interactions with the Earth’s magnetosphere). The most difficult problem in monitoring and forecasting the modulation of galactic CR in the heliosphere is that the CR intensity in some 4D space-time point is determined not by the level of solar activity at the time of observations and electro-magnetic conditions in this 4D-point, but rather by electromagnetic conditions in the whole heliosphere. These conditions in the whole heliosphere are determined by the development of solar activity over the course of many months before the time-point of observations. This is the main cause of the so-called hysteresis phenomenon in connection with galactic CR - solar activity. On the other hand, detailed investigations of this phenomenon give the important possibility to estimate conditions in and the dimension of the heliosphere. To solve the problem described above of CR modulation in the heliosphere, we considered as the first step the behavior of high energy particles (more than several GeV, for which the diffusion time of propagation in the heliosphere is very small in compared to the characteristic time of modulation), on the basis of neutron monitor data in the frame of convection diffusion theory, then taking into account drift effects. For low energy galactic CR detected on satellites and space probes, we also need to take into account the additional time lag caused by diffusion in the heliosphere. We then consider the problem of CR modulation forecasting for several months and years ahead, which gives the possibility to forecast some part of the global climate change caused by CR.

  19. Optimal precursor ion selection for LC-MALDI MS/MS

    PubMed Central

    2013-01-01

    Background Liquid chromatography mass spectrometry (LC-MS) maps in shotgun proteomics are often too complex to select every detected peptide signal for fragmentation by tandem mass spectrometry (MS/MS). Standard methods for precursor ion selection, commonly based on data dependent acquisition, select highly abundant peptide signals in each spectrum. However, these approaches produce redundant information and are biased towards high-abundance proteins. Results We present two algorithms for inclusion list creation that formulate precursor ion selection as an optimization problem. Given an LC-MS map, the first approach maximizes the number of selected precursors given constraints such as a limited number of acquisitions per RT fraction. Second, we introduce a protein sequence-based inclusion list that can be used to monitor proteins of interest. Given only the protein sequences, we create an inclusion list that optimally covers the whole protein set. Additionally, we propose an iterative precursor ion selection that aims at reducing the redundancy obtained with data dependent LC-MS/MS. We overcome the risk of erroneous assignments by including methods for retention time and proteotypicity predictions. We show that our method identifies a set of proteins requiring fewer precursors than standard approaches. Thus, it is well suited for precursor ion selection in experiments with limited sample amount or analysis time. Conclusions We present three approaches to precursor ion selection with LC-MALDI MS/MS. Using a well-defined protein standard and a complex human cell lysate, we demonstrate that our methods outperform standard approaches. Our algorithms are implemented as part of OpenMS and are available under http://www.openms.de. PMID:23418672

  20. Improved method for measuring transparent exopolymer particles (TEP) and their precursors in fresh and saline water.

    PubMed

    Villacorte, Loreen O; Ekowati, Yuli; Calix-Ponce, Helga N; Schippers, Jan C; Amy, Gary L; Kennedy, Maria D

    2015-03-01

    Transparent exopolymer particles (TEP) and their precursors produced by phyto-/bacterio-planktons in fresh and marine aquatic environments are increasingly considered as a major contributor to organic/particulate and biological fouling in micro-/ultra-filtration and reverse osmosis membrane (RO) systems. However, currently established methods which are based on Alcian blue (AB) staining and spectrophotometric techniques do not measure TEP-precursors and have the tendency to overestimate concentration in brackish/saline water samples due to interference of salinity on AB staining. Here we propose a new semi-quantitative method which allows measurement of both TEP and their colloidal precursors without the interference of salinity. TEP and their precursors are first retained on 10 kDa membrane, rinsed with ultra-pure water, and re-suspended in ultra-pure water by sonication and stained with AB, followed by exclusion of TEP-AB precipitates by filtration and absorbance measurement of residual AB. The concentration is then determined based on the reduction of AB absorbance due to reaction with acidic polysaccharides, blank correction and calibration with Xanthan gum standard. The extraction procedure allows concentration of TEP and their pre-cursors which makes it possible to analyse samples with a wide range of concentrations (down to <0.1 mg Xeq/L). This was demonstrated through application of the method for monitoring these compounds in algal cultures and a full-scale RO plant. The monitoring also revealed that concentrations of the colloidal precursors were substantially higher than the concentration of TEP themselves. In the RO plant, complete TEP removal was observed over the pre-treatment processes (coagulation-sedimentation-filtration and ultrafiltration) but the TEP precursors were not completely removed, emphasising the importance of measuring this colloidal component to better understand the role of TEP and acidic polysaccharides in RO membrane fouling. PMID:25543240