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1

Preference for Gamma-Hydroxybutyrate (GHB) in Current Users  

ERIC Educational Resources Information Center

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…

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

2012-01-01

2

Preference for Gamma-Hydroxybutyrate (GHB) in Current Users  

PubMed Central

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 current GHB users who were not currently trying to stop using GHB. To examine the value of escalating doses of GHB, the following doses of GHB were used: 0 (placebo), 12.5, 25, 37.5, and 50 mg/kg. Participants typically assigned higher doses of GHB had higher crossover points on the MCP. During choice sessions, participants made repeated choices between administering GHB, placebo or nothing. All participants selected GHB exclusively (5 out of 5 instances) except for one participant who selected GHB on 4 out of 5 instances, thus 96% (i.e., 24/25) of choices were for active GHB. Based on these data, GHB appears likely to function as a dose-dependent reinforcer for humans based on our sample. PMID:22693361

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

2012-01-01

3

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

PubMed Central

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

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

2008-01-01

4

BEHAVIORAL EFFECTS OF GAMMA-HYDROXYBUTYRATE (GHB) IN HUMANS  

PubMed Central

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

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

2010-01-01

5

Gamma-Hydroxybutyrate (GHB): A Scoping Review of Pharmacology, Toxicology, Motives for Use, and User Groups.  

PubMed

Abstract 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

Brennan, Rebekah; Van Hout, Marie Claire

2014-01-01

6

A web-based study of gamma hydroxybutyrate (GHB): patterns, experiences, and functions of use.  

PubMed

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

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

2011-01-01

7

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

Microsoft Academic Search

In forensic evidence, the identification and quantitation of gamma-hydroxybutyric acid (GHB) in “spiked” beverages is challenging. In this report, we present the analysis of common alcoholic beverages found in clubs and bars spiked with gamma-hydroxybutyric acid (GHB) and gamma-butyrolactone (GBL). Our analysis of the spiked beverages consisted of using 1H NMR with a water suppression method called Presaturation Utilizing Relaxation

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

2011-01-01

8

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

PubMed

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

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

2009-10-01

9

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

PubMed

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

Brown, Andrew J

2007-01-01

10

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

PubMed

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

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

2014-10-01

11

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

PubMed

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

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

2011-10-10

12

Gamma-Hydroxybutyrate (GHB)  

MedlinePLUS

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13

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

PubMed

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

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

2014-03-28

14

The clinical toxicology of gamma-hydroxybutyrate, gamma-butyrolactone and 1,4-butanediol  

Microsoft Academic Search

INTRODUCTION: Gamma-hydroxybutyrate (GHB) and its precursors, gamma-butyrolactone (GBL) and 1,4-butanediol (1,4-BD), are drugs of abuse which act primarily as central nervous system (CNS) depressants. In recent years, the rising recreational use of these drugs has led to an increasing burden upon health care providers. Understanding their toxicity is therefore essential for the successful management of intoxicated patients. We review the

L. J. Schep; K. Knudsen; R. J. Slaughter; J. A. Vale; B. Megarbane

2012-01-01

15

Forensic toxicology findings in deaths involving gamma-hydroxybutyrate  

Microsoft Academic Search

Concentrations of the illicit drug gamma-hydroxybutyrate (GHB) were determined in femoral venous blood and urine obtained\\u000a at autopsy in a series of GHB-related deaths (N?=?49). The analysis of GHB was done by gas chromatography after conversion to gamma-butyrolactone and quantitation of the\\u000a latter with a flame ionization detector. The cutoff concentration of GHB in femoral blood or urine for reporting

Fredrik C. Kugelberg; Anita Holmgren; Arne Eklund; Alan Wayne Jones

2010-01-01

16

Safety and tolerability of gamma-hydroxybutyric acid in the treatment of alcohol-dependent patients  

Microsoft Academic Search

Gamma-hydroxybutyric acid (GHB) has been in clinical use in Italy since 1991 for treatment of alcohol dependence. Results of phase III and phase IV studies have shown that the drug is effective and well tolerated in the treatment of alcohol withdrawal syndrome and in reducing alcohol consumption and alcohol craving. Pharmacosurveillance indicates that abuse of gamma-hydroxybutyric acid is a limited

Franco Beghè; Maria Teresa Carpanini

2000-01-01

17

An overview of gamma-hydroxybutyric acid: pharmacodynamics, pharmacokinetics, toxic effects, addiction, analytical methods, and interpretation of results.  

PubMed

Abuse of gamma-hydroxybutyric acid (GHB) has been known since the early 1990's, but is not as widespread as the consumption of other illegal drugs. However, the number of severe intoxications with fatal outcomes is comparatively high; not the least of which is brought about by the consumption of the currently legal precursor substances gamma-butyrolactone (GBL) and 1,4-butanediol (1,4-BD). In regards to previous assumptions, addiction to GHB or its analogues can occur with severe symptoms of withdrawal. Moreover, GHB can be used for drug-facilitated sexual assaults. Its pharmacological effects are generated mainly by interaction with both GABA(B) and GHB receptors, as well as its influence on other transmitter systems in the human brain. Numerous analytical methods for determining GHB using chromatographic techniques were published in recent years, and an enzymatic screening method was established. However, the short window of GHB detection in blood or urine due to its rapid metabolism is a challenge. Furthermore, despite several studies addressing this problem, evaluation of analytical results can be difficult: GHB is a metabolite of GABA (gamma-aminobutyric acid); a differentiation between endogenous and exogenous concentrations has to be made. Apart from this, in samples with a longer storage interval and especially in postmortem specimens, higher levels can be measured due to GHB generation during this postmortem interval or storage time. PMID:21381220

Andresen, H; Aydin, B E; Mueller, A; Iwersen-Bergmann, S

2011-09-01

18

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

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

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

2005-03-01

19

The Clinical Development of ?-Hydroxybutyrate (GHB)  

Microsoft Academic Search

The discovery of gamma-hydroxybutyrate (GHB) over 40 years ago led to its immediate use as a general anesthetic agent. Subsequent research demonstrated that GHB is an endogenous compound in the mammalian brain and current research suggests that GHB is a probable neurotransmitter. In the United States, reports of anabolic effects lead to its misuse among body builders during the 1980's

Gregory P. Wedin; Carl S. Hornfeldt; Lisa M. Ylitalo

2006-01-01

20

Intravenous self-administration of gamma-hydroxybutyric acid in drug-naive mice  

Microsoft Academic Search

The reinforcing effects of gamma-hydroxybutyric acid (GHB) were studied by means of intravenous self-administration in drug-naive mice. GHB self-administration was concentration-dependent (0.01–0.5 mg\\/kg\\/inj) according to a bell-shaped curve. Pretreatment with the specific GHB receptor antagonist NCS-382 at a dose of 12.5 mg\\/kg i.p. completely antagonized the reinforcing effects of GHB. These data suggest that GHB is able to induce reinforcing

M. C Martellotta; G Cossu; L Fattore; G. L Gessa; W Fratta

1998-01-01

21

Safety and tolerability of gamma-hydroxybutyric acid in the treatment of alcohol-dependent patients.  

PubMed

Gamma-hydroxybutyric acid (GHB) has been in clinical use in Italy since 1991 for treatment of alcohol dependence. Results of phase III and phase IV studies have shown that the drug is effective and well tolerated in the treatment of alcohol withdrawal syndrome and in reducing alcohol consumption and alcohol craving. Pharmacosurveillance indicates that abuse of gamma-hydroxybutyric acid is a limited phenomenon in clinical settings when the drug is dispensed under strict medical surveillance and entrusted to a referring familiar member of the patient. PMID:10869863

Beghè, F; Carpanini, M T

2000-04-01

22

Coma in a 20-month-old child from an ingestion of a toy containing 1,4-butanediol, a precursor of gamma-hydroxybutyrate.  

PubMed

Ingestion of plastic toys is common in children and usually does not result in harm. We report a case of coma in a 20-month-old child after an ingestion of a toy containing 1,4-butanediol, an industrial solvent used to manufacture plastics. When ingested, 1,4-butanediol is metabolized to gamma-hydroxybutyrate, which can have significant systemic effects including death. Health care providers should suspect the possibility of a toxic component when a presumed nontoxic object causes unusual symptoms. PMID:19915428

Ortmann, Laura A; Jaeger, Matthew W; James, Laura P; Schexnayder, Steve M

2009-11-01

23

Two cases of severe gamma-hydroxybutyrate withdrawal delirium on a psychiatric unit: recommendations for management.  

PubMed

Many psychiatric professionals are unfamiliar with gamma-hydroxybutyrate (GHB), an increasingly popular drug of abuse. GHB withdrawal can lead to psychosis and agitation, and patients may present to psychiatric facilities for treatment. Withdrawal may progress to delirium, with the potential for severe or even fatal medical complications. Therefore, it is imperative for psychiatric professionals to understand how to treat these patients. In this article, we describe two cases of severe GHB withdrawal syndrome that were treated in our inpatient psychiatric unit. These are among the most severe cases reported. Pertinent literature is reviewed and suggestions for treatment are discussed. PMID:12765217

Rosenberg, Mark H; Deerfield, Laurie J; Baruch, Edward M

2003-05-01

24

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

PubMed

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

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

2010-06-01

25

Club drugs: methylenedioxymethamphetamine, flunitrazepam, ketamine hydrochloride, and gamma-hydroxybutyrate.  

PubMed

The abuse of methylenedioxymethamphetamine (MDMA), flunitrazepam, ketamine hydrochloride, and gamma-hydroxybutyrate (GHB) is discussed. Club drugs are chemical substances used recreationally in social settings. Use is increasingly frequent among young people, especially during all-night dance parties. All four agents have been classified as controlled substances. MDMA ("ecstasy") is available as a tablet, a capsule, and a powder; formulations may contain many adulterants. MDMA increases the release of neurotransmitters. The desired effects are euphoria, a feeling of intimacy, altered visual perception, enhanced libido, and increased energy. The most common adverse effects are agitation, anxiety, tachycardia, and hypertension. More serious adverse effects include arrhythmias, hyperthermia, and rhabdomyolysis. Flunitrazepam is a potent benzodiazepine. At higher doses, the drug can cause lack of muscle control and loss of consciousness. Other adverse effects are hypotension, dizziness, confusion, and occasional aggression. Ketamine is a dissociative anesthetic used primarily in veterinary practice. It may be injected, swallowed, snorted, or smoked. Like phencyclidine, ketamine interacts with the N-methyl-D-aspartate channel. Analgesic effects occur at lower doses and amnestic effects at higher doses. Cardiovascular and respiratory toxicity may occur, as well as confusion, hostility, and delirium. GHB, a naturally occurring fatty acid derivative of gamma-aminobutyric acid, was introduced as a dietary supplement. Increasing doses progressively produce amnesia, drowsiness, dizziness, euphoria, seizures, coma, and death. Flunitrazepam, ketamine, and GHB have been used to facilitate sexual assault. Supportive care is indicated for most cases of club drug intoxication. The increasing abuse of MDMA, flunitrazepam, ketamine hydrochloride, and GHB, particularly by young people in social settings such as clubs, should put health care professionals on guard to recognize and manage serious reactions. PMID:12063892

Smith, Kelly M; Larive, Lisa L; Romanelli, Frank

2002-06-01

26

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

PubMed Central

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

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

2014-01-01

27

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

PubMed

The gamma-aminobutyric acid (GABA) metabolite gamma-hydroxybutyric acid (GHB) shows a variety of behavioural effects when administered to animals and humans, including reward/addiction properties and absence seizures. At the cellular level, these actions of GHB are mediated by activation of neuronal GABAB receptors (GABABRs) where it acts as a weak agonist. Because astrocytes respond to endogenous and exogenously applied GABA by activation of both GABAA and GABABRs, here we investigated the action of GHB on astrocytes on the ventral tegmental area (VTA) and the ventrobasal (VB) thalamic nucleus, two brain areas involved in the reward and proepileptic action of GHB, respectively, and compared it with that of the potent GABABR agonist baclofen. We found that GHB and baclofen elicited dose-dependent (ED50: 1.6 mM and 1.3 µM, respectively) transient increases in intracellular Ca(2+) in VTA and VB astrocytes of young mice and rats, which were accounted for by activation of their GABABRs 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

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

2014-10-19

28

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

NASA Astrophysics Data System (ADS)

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.

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

1998-06-01

29

Analysis of Electrical Brain Waves in Neurotoxicology: Gamma-Hydroxybutyrate  

PubMed Central

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 alpha1 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 beta2 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

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

2011-01-01

30

Pathway-specific action of gamma-hydroxybutyric acid in sensory thalamus and its relevance to absence seizures.  

PubMed

The systemic injection of gamma-hydroxybutyric acid (GHB) elicits spike and wave discharges (SWDs), the EEG hallmark of absence seizures, and represents a well established, widely used pharmacological model of this nonconvulsive epilepsy. Despite this experimental use of GHB, as well as its therapeutic use in narcolepsy and its increasing abuse, however, the precise cellular mechanisms underlying the different pharmacological actions of this drug are still unclear. Because sensory thalamic nuclei play a key role in the generation of SWDs and sleep rhythms, and because direct injection of GHB in the ventrobasal (VB) thalamus elicits SWDs, we investigated GHB effects on corticothalamic EPSCs and GABAergic IPSCs in VB thalamocortical (TC) neurons. GHB (250 microm-10 mm) reversibly decreased the amplitude of electrically evoked EPSCs and GABAA IPSCs via activation of GABAB receptors; however, approximately 60% of the IPSCs were insensitive to low (250 microm-1.0 mm) GHB concentrations. The putative GHB receptor antagonist NSC 382 applied alone had a number of unspecific effects, whereas it either had no action on, or further increased, the GHB-elicited effects on synaptic currents. Low GHB concentrations (250 microm) were also effective in increasing absence-like intrathalamic oscillations evoked by cortical afferent stimulation. These results indicate that low concentrations of GHB, similar to the brain concentrations that evoke SWDs in vivo, differentially affect excitatory and inhibitory synaptic currents in TC neurons and promote absence-like intrathalamic oscillations. Furthermore, the present data strengthen previous suggestions on the GHB mechanism of sleep promotion and will help focus future studies on the cellular mechanisms underlying its abuse. PMID:14673012

Gervasi, Nicolas; Monnier, Zohreh; Vincent, Pierre; Paupardin-Tritsch, Daniele; Hughes, Stuart W; Crunelli, Vincenzo; Leresche, Nathalie

2003-12-10

31

Determination of gamma-hydroxybutyric acid in dried blood spots using a simple GC-MS method with direct “on spot” derivatization  

Microsoft Academic Search

The objective of this study was the development of an accurate and sensitive method for the determination of gamma-hydroxybutyric\\u000a acid (GHB) in dried whole blood samples using a GC-MS method. The complete procedure was optimized, with special attention\\u000a on the sample pretreatment, and validated. Therefore, dried blood spots of only 50 ?l were prepared and, after the addition\\u000a of internal standard

Ann-Sofie M. E. Ingels; Willy E. Lambert; Christophe P. Stove

2010-01-01

32

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

PubMed

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

Korb, Ann-Sophie; Cooper, Gail

2014-10-01

33

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

Microsoft Academic Search

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).

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

2006-01-01

34

21 CFR 1304.26 - Additional recordkeeping requirements applicable to drug products containing gamma-hydroxybutyric...  

Code of Federal Regulations, 2012 CFR

...requirements applicable to drug products containing gamma-hydroxybutyric acid. 1304.26 Section 1304.26 Food and Drugs DRUG ENFORCEMENT...requirements applicable to drug products containing gamma-hydroxybutyric acid. In addition...

2012-04-01

35

21 CFR 1304.26 - Additional recordkeeping requirements applicable to drug products containing gamma-hydroxybutyric...  

Code of Federal Regulations, 2011 CFR

...requirements applicable to drug products containing gamma-hydroxybutyric acid. 1304.26 Section 1304.26 Food and Drugs DRUG ENFORCEMENT...requirements applicable to drug products containing gamma-hydroxybutyric acid. In addition...

2011-04-01

36

21 CFR 1304.26 - Additional recordkeeping requirements applicable to drug products containing gamma-hydroxybutyric...  

Code of Federal Regulations, 2010 CFR

...requirements applicable to drug products containing gamma-hydroxybutyric acid. 1304.26 Section 1304.26 Food and Drugs DRUG ENFORCEMENT...requirements applicable to drug products containing gamma-hydroxybutyric acid. In addition...

2010-04-01

37

21 CFR 1304.26 - Additional recordkeeping requirements applicable to drug products containing gamma-hydroxybutyric...  

Code of Federal Regulations, 2013 CFR

...requirements applicable to drug products containing gamma-hydroxybutyric acid. 1304.26 Section 1304.26 Food and Drugs DRUG ENFORCEMENT...requirements applicable to drug products containing gamma-hydroxybutyric acid. In addition...

2013-04-01

38

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

PubMed Central

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

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

2014-01-01

39

GHB acid: A rage or reprive  

PubMed Central

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

Kapoor, Prakhar; Deshmukh, Revati; Kukreja, Ipsita

2013-01-01

40

Comparative analysis of gamma-hydroxybutyrate and gamma-hydroxyvalerate using GC/MS and HPLC.  

PubMed

This paper describes two analytical techniques used to separate and quantify gamma-hydroxybutyrate (GHB) and gamma-hydroxyvalerate (GHV). The first technique was a N,O-bis(trimethylsilyl)triflouro-acetimide-trimethylchlorosilane derivatization, followed by gas chromatography/mass spectrometry analysis using an HP-5 capillary column at a rate of 1.0 mL/min with a run time of 9.25 min. This technique was found to be sensitive (LOD 1 pg on column) and gave a low average error (5%) in a beverage study. When supplemented by a surrogate spike, the method yielded 97% analyte recovery from beverages. The second technique was high-performance liquid chromatography/UV (HPLC/UV) using a C-18 column with a (20:80% v/v) methanol:dibasic phosphoric buffer (10 mM, pH 3) at a rate of 1.00 mL/min with a run time of 7.5 min. UV detection occurred at 254 nm. This method was found to be less sensitive (LOD 0.05 microg on column) for direct analysis of aqueous samples. To remove interferences seen in the beverage study, a liquid-liquid extraction before HPLC analysis was tested. However, a decreased sensitivity (LOD 100 microg on column) and irreproducible peak profiles resulted. PMID:17316236

Mercer, Jennifer W; Oldfield, Lucy S; Hoffman, Kristin N; Shakleya, Diaa M; Bell, Suzanne C

2007-03-01

41

Comparative abuse liability of GHB and ethanol in humans  

PubMed Central

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

Johnson, Matthew W.; Griffiths, Roland R.

2013-01-01

42

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

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

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

2014-10-01

43

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

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

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

2010-07-01

44

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

?-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 (1000mg/kg) and GBL (600mg/kg) induced rapid sedation in rats that lasted over 90min 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

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

2014-09-26

45

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

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

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

2002-01-01

46

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

PubMed Central

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

Meyer, Rafael; Jenewein, Josef

2014-01-01

47

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

PubMed Central

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

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

2013-01-01

48

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

Federal Register 2010, 2011, 2012, 2013

...Administration (DEA) to be registered as a bulk manufacturer of Gamma Hydroxybutyric Acid (GHB) (2010), a basic class of controlled...substance listed in schedule I. The company plans to manufacture Gamma Hydroxybutyric Acid (GHB) (2010) in bulk active...

2010-09-01

49

What You Need to Know about Drugs: GHB  

MedlinePLUS

... GHB can kill you. Because both GHB and alcohol are depressants, mixing the two is very, very dangerous and can be deadly — even ... ON THIS TOPIC Dealing With Peer Pressure What You Need to Know About Drugs ...

50

Differential effects of GABAB receptor subtypes, {gamma}-hydroxybutyric Acid, and Baclofen on EEG activity and sleep regulation.  

PubMed

The role of GABA(B) receptors in sleep is still poorly understood. GHB (?-hydroxybutyric acid) targets these receptors and is the only drug approved to treat the sleep disorder narcolepsy. GABA(B) receptors are obligate dimers comprised of the GABA(B2) subunit and either one of the two GABA(B1) subunit isoforms, GABA(B1a) and GABA(B1b). To better understand the role of GABA(B) receptors in sleep regulation, we performed electroencephalogram (EEG) recordings in mice devoid of functional GABA(B) receptors (1(-/-) and 2(-/-)) or lacking one of the subunit 1 isoforms (1a(-/-) and 1b(-/-)). The distribution of sleep over the day was profoundly altered in 1(-/-) and 2(-/-) mice, suggesting a role for GABA(B) receptors in the circadian organization of sleep. Several other sleep and EEG phenotypes pointed to a more prominent role for GABA(B1a) compared with the GABA(B1b) isoform. Moreover, we found that GABA(B1a) protects against the spontaneous seizure activity observed in 1(-/-) and 2(-/-) mice. We also evaluated the effects of the GHB-prodrug GBL (?-butyrolactone) and of baclofen (BAC), a high-affinity GABA(B) receptor agonist. Both drugs induced a state distinct from physiological sleep that was not observed in 1(-/-) and 2(-/-) mice. Subsequent sleep was not affected by GBL whereas BAC was followed by a delayed hypersomnia even in 1(-/-) and 2(-/-) mice. The differential effects of GBL and BAC might be attributed to differences in GABA(B)-receptor affinity. These results also indicate that all GBL effects are mediated through GABA(B) receptors, although these receptors do not seem to be involved in mediating the BAC-induced hypersomnia. PMID:20962240

Vienne, Julie; Bettler, Bernhard; Franken, Paul; Tafti, Mehdi

2010-10-20

51

A validated GC-MS procedure for fast, simple, and cost-effective quantification of glycols and GHB in human plasma and their identification in urine and plasma developed for emergency toxicology.  

PubMed

Methods developed for use in emergency toxicology have to be fast and simple. Additionally, such methods should be multi-analyte procedures because they allow monitoring of analytes of different drug classes in one single body sample. This is important because often only a limited amount of sample is available and the results have to be reported as fast as possible. Therefore, we describe the improvement of an existing method published by van Hee at al. The new method is fast and simple and designed for the simultaneous determination of ethylene glycol, 1,2-propylene glycol, lactic acid, glycolic acid, gamma-hydroxybutyric acid (GHB), diethylene glycol, triethylene glycol, and tetraethylene glycol in human plasma or urine. A 50-?L aliquot of sample was deproteinized and 20 ?l of the diluted specimen were derivatized using bis-N,O-trimethylsilyl trifluoroacetamide and the catalyst dimethylformamide. After microwave-assisted derivatization, an aliquot was injected into the gas chromatograph and analyzed with electron ionization mass spectrometry in selective ion monitoring mode. All compounds are separated within 12 min and detected with a limit of quantification of 0.05 and 0.01 g/L for glycols and GHB, respectively. Calibration was linear from 0.05 to 1.0 g/L for glycols and 0.01 to 0.2 g/L for GHB. Validation criteria were shown to be in the required limits with exception of lactic acid. Average analysis time from starting sample preparation until quantitative plasma results of approximately 35 min was achieved. This turnaround time is considered most appropriate for emergency cases. PMID:21336790

Meyer, Markus R; Weber, Armin A; Maurer, Hans H

2011-04-01

52

Reconsidering GHB: orphan drug or new model antidepressant?  

PubMed

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

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

2012-05-01

53

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

PubMed

?-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

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

2014-01-15

54

GHB and synthetic cathinones: clinical effects and potential consequences.  

PubMed

Designer drugs belong to a group of legally or illegally produced substances that are structurally and pharmacologically very similar to illicit drugs. In the past, designer drugs were often used during all-night dance parties, but they are now consumed in multiple settings from college bars to parks to private house parties. Most of these club drugs can be bought on legal websites and home-delivered for private parties. Recently, legal highs have once again become a burning media issue across the world. Our review will focus on GHB and synthetic cathinones. Literature searches were conducted for the period from 1975 to July 2010 using PubMed, EMBASE, PsycInfo, Internet underground and governmental websites using the following keywords alone or in combination: designer drugs, club drugs, party drugs, GHB, synthetic cathinones, mephedrone, methylone, flephedrone, MDAI, and MDVP. Available epidemiological, neurobiological, and clinical data for each compound are described. There is evidence that negative health and social consequences may occur in recreational and chronic users. The addictive potential of designer drugs is not weak. Non-fatal overdoses and deaths related to GHB/GBL or synthetic cathinones have been reported. Clinicians must be careful with GBL or synthetic cathinones, which are being sold and used as substitutes for GHB and MDMA, respectively. Interventions for drug prevention and harm reduction in response to the use of these drugs should be implemented on the Internet and in recreational settings. Prevention, Information, Action, and Treatment are the main goals that must be addressed for this new potentially addictive problem. PMID:21960540

Karila, Laurent; Reynaud, Michel

2011-09-01

55

?4?? GABAA receptors are high-affinity targets for ?-hydroxybutyric acid (GHB)  

PubMed Central

?-Hydroxybutyric acid (GHB) binding to brain-specific high-affinity sites is well-established and proposed to explain both physiological and pharmacological actions. However, the mechanistic links between these lines of data are unknown. To identify molecular targets for specific GHB high-affinity binding, we undertook photolinking studies combined with proteomic analyses and identified several GABAA receptor subunits as possible candidates. A subsequent functional screening of various recombinant GABAA receptors in Xenopus laevis oocytes using the two-electrode voltage clamp technique showed GHB to be a partial agonist at ???- but not ???-receptors, proving that the ?-subunit is essential for potency and efficacy. GHB showed preference for ?4 over ?(1,2,6)-subunits and preferably activated ?4?1? (EC50 = 140 nM) over ?4?(2/3)? (EC50 = 8.41/1.03 mM). Introduction of a mutation, ?4F71L, in ?4?1(?)-receptors completely abolished GHB but not GABA function, indicating nonidentical binding sites. Radioligand binding studies using the specific GHB radioligand [3H](E,RS)-(6,7,8,9-tetrahydro-5-hydroxy-5H-benzocyclohept-6-ylidene)acetic acid showed a 39% reduction (P = 0.0056) in the number of binding sites in ?4 KO brain tissue compared with WT controls, corroborating the direct involvement of the ?4-subunit in high-affinity GHB binding. Our data link specific GHB forebrain binding sites with ?4-containing GABAA receptors and postulate a role for extrasynaptic ?4?-containing GABAA receptors in GHB pharmacology and physiology. This finding will aid in elucidating the molecular mechanisms behind the proposed function of GHB as a neurotransmitter and its unique therapeutic effects in narcolepsy and alcoholism. PMID:22753476

Absalom, Nathan; Eghorn, Laura F.; Villumsen, Inge S.; Karim, Nasiara; Bay, Tina; Olsen, Jesper V.; Knudsen, Gitte M.; Bräuner-Osborne, Hans; Frølund, Bente; Clausen, Rasmus P.; Chebib, Mary; Wellendorph, Petrine

2012-01-01

56

Three deaths associated with use of Xyrem ®  

Microsoft Academic Search

Fatalities resulting from popular use of gamma hydroxybutyrate (GHB) have previously been reported. We report three deaths associated with use of Xyrem® (sodium oxybate), a pharmaceutical preparation of GHB initially approved for treatment of narcolepsy with cataplexy. One death appears associated with Xyrem® abuse, with extremely high postmortem blood GHB levels documented. Although postmortem blood GHB levels in two other

Deborah L. Zvosec; Stephen W. Smith; Brad J. Hall

2009-01-01

57

Gammahydroxybutyrate Reduces GABAA-mediated Inhibitory Postsynaptic Potentials in the CA1 Region of Hippocampus  

Microsoft Academic Search

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 GABAB receptors. Previous studies indicated that GHB inhibits both NMDA and AMPA receptor mediated excitatory postsynaptic

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

2002-01-01

58

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

PubMed Central

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

Vogensen, Stine B.; Marek, Ales; Bay, Tina; Wellendorph, Petrine; Kehler, Jan; Bundgaard, Christoffer; Fr?lund, Bente; Pedersen, Martin H.F.; Clausen, Rasmus P.

2013-01-01

59

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

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

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

2014-04-01

60

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

PubMed Central

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

2014-01-01

61

Trends in the use of alcohol and other drugs in cases of sexual assault  

Microsoft Academic Search

Recent media coverage has raised awareness of the involvement of drugs, both licit and illicit, in the crime of 'date' or 'acquaintance' rape. The term 'date rape drug' has been coined and has been used to label a few specific drugs because of their alleged properties. These include flunitrazepam (Rohypnol), gamma hydroxybutyrate (GHB) and ketamine. Concerns over reports of flunitrazepam

Ian Hindmarch; Rüdiger Brinkmann

1999-01-01

62

Monochromatic precursor starts  

NASA Astrophysics Data System (ADS)

Whistler precursors are discrete emissions that precede two-hop whistlers, starting shortly after the one-hop delay. More evidence is presented that the precursor and associated whistler propagate through the same duct, and observations of a new type of precursor are presented. This new precursor has a monochromatic precursor start (MPS) which may or may not trigger a riser. Although MPS's may be emissions entrained by power line radiation (PLR), phase analysis of the starting frequencies shows that they are not simply related to harmonics of the power line frequencies in the two conjugate regions (50 Hz in New Zealand, 60 Hz in Alaska). If the MPS is due to entrainment by PLR, then previous theories of precursor generation need not be discarded. Forward triggering of a precursor at a power line harmonic by a hybrid whistler may occur.

Rietveld, M. T.

1980-05-01

63

Precursors to Lymphoproliferative Malignancies  

PubMed Central

We review monoclonal B-cell lymphocytosis (MBL) as a precursor to chronic lymphocytic leukemia and monoclonal gammopathy of undetermined significance (MGUS) as a precursor to plasma cell disorders. These conditions are present in the general population and increase with age. These precursors aggregate with lymphoproliferative malignancies in families suggesting shared inheritance. MBL and MGUS may share some of the same risk factors as their related malignancies but data are limited. While these conditions are characterized by enhanced risk for the associated malignancy, the majority of individuals with these conditions do not progress to malignancy. A key focus for current work is to identify markers that predict progression to malignancy. PMID:23549397

Goldin, Lynn R.; McMaster, Mary L.; Caporaso, Neil E.

2013-01-01

64

Earthquakes: Hydrogeochemical precursors  

NASA Astrophysics Data System (ADS)

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.

Ingebritsen, S. E.; Manga, M.

2014-10-01

65

The Pharmacokinetics of Sodium Oxybate Oral Solution following Acute and Chronic Administration to Narcoleptic Patients  

Microsoft Academic Search

This trial was conducted to evaluate the pharmacokinetics and safety of a sodium oxybate (gamma-hydroxybutyrate [GHB]) oral solution in narcoleptic patients after acute and chronic treatment. An open-label, two-period, two-treatment study design was used. Trial subjects included 13 patients with polysomnographically confirmed narcolepsy. The patients were administered a bedtime dose of 4.5 g of sodium oxybate while in a sleep

Lowell A. Borgen; Richard A. Okerholm; Allen Lai; Martin B. Scharf

2004-01-01

66

Sexual risk taking and club drug use across three age cohorts of HIV-positive gay and bisexual men in New York City  

Microsoft Academic Search

This study examined club drug use (i.e., cocaine, ecstasy, ketamine, gamma-hydroxybutyrate [GHB], and methamphetamine) and unprotected anal intercourse (UAI) in an ethnically and racially diverse sample of 166 New York City-based seropositive, club drug-using, gay and bisexual men, ages 19–61, and considered these behaviors in relation to age category (20s, 30s, and 40 +) and number of years living with

Molly K. Pappas; Perry N. Halkitis

2011-01-01

67

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

Microsoft Academic Search

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

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

68

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

Microsoft Academic Search

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

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

2007-01-01

69

Identification of Desirable Precursor Properties for Solution Precursor Plasma Spray  

NASA Astrophysics Data System (ADS)

In solution precursor plasma spray chemical precursor solutions are injected into a standard plasma torch and the final material is formed and deposited in a single step. This process has several attractive features, including the ability to rapidly explore new compositions and to form amorphous and metastable phases from molecularly mixed precursors. Challenges include: (a) moderate deposition rates due to the need to evaporate the precursor solvent, (b) dealing on a case by case basis with precursor characteristics that influence the spray process (viscosity, endothermic and exothermic reactions, the sequence of physical states through which the precursor passes before attaining the final state, etc.). Desirable precursor properties were identified by comparing an effective precursor for yttria-stabilized zirconia with four less effective candidate precursors for MgO:Y2O3. The critical parameters identified were a lack of major endothermic events during precursor decomposition and highly dense resultant particles.

Muoto, Chigozie K.; Jordan, Eric H.; Gell, Maurice; Aindow, Mark

2011-06-01

70

OXIDANT-PRECURSOR RELATIONSHIPS  

EPA Science Inventory

New methods of ambient air analysis were used to define more clearly the relationships between oxidants and their precursors. Non-methane hydrocarbons, NOx, O2, and oxidants were measured at the same time and location (Riverside, California). The ambient air data presented in thi...

71

Gamma butyrolactone poisoning and its similarities to gamma hydroxybutyric acid: two case reports.  

PubMed

Clinical experience with toxicity induced by products containing gamma butyrolactone is limited. We report here 2 cases of gamma butyrolactone poisoning with a nail polish remover labelled "acetone-free". Rapid onset of coma, respiratory depression and bradycardia occurred in both patients. After supportive care, they fully recovered within a few hours. PMID:9251175

Rambourg-Schepens, M O; Buffet, M; Durak, C; Mathieu-Nolf, M

1997-08-01

72

The EM Earthquake Precursor  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

73

Identified EM Earthquake Precursors  

NASA Astrophysics Data System (ADS)

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.

Jones, Kenneth, II; Saxton, Patrick

2014-05-01

74

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, ...

75

Preparation of superconductor precursor powders  

DOEpatents

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

Bhattacharya, Raghunath (Littleton, CO)

1998-01-01

76

Laboratory experiments examine earthquake precursors  

NASA Astrophysics Data System (ADS)

Although it is not possible to predict when an earthquake will occur, many earthquakes have been found to have had some precursor activity. To study precursors of stick-slip behavior, Johnson et al. conducted laboratory experiments on a sheared granular material under normal stress ranging from 2 to 8 megapascals as an analog for a fault under tectonic stress. They found that acoustic emissions and microslips are a precursor to larger movements. Very similar results were obtained in a discrete element simulation of sheared beads. These types of experiments could help scientists better understand when earthquakes are more likely to occur. As shown by a number of researchers, very similar activity preceding faulting can occur in the Earth.

Balcerak, Ernie

2014-01-01

77

Preparation of superconductor precursor powders  

DOEpatents

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

Bhattacharya, R.

1998-08-04

78

Precursors of Short Gamma-Ray Bursts  

NASA Technical Reports Server (NTRS)

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.

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

2010-01-01

79

New Worlds Observer Precursor Mission  

NASA Astrophysics Data System (ADS)

The New Worlds Observer architecture uses an external occulter to extinguish the on-axis light from a star and a separate telescope to collect the light from objects around that star, such as planets and debris disks. The separation of the starlight suppression capability from the photon collection capability makes the New Worlds Observer architecture very flexible. This paper describes NWO concepts ranging from low-cost precursor missions to Terrestrial Planet Finding (TPF) missions, and provides a path that extends beyond TPF to Planet-Imager and LifeFinder. Low cost precursor missions could be launched on a Minotaur using a small(~10 meter) occulter to work with a small(~0.5 m), telescope. Intermediate precursor missions could be accomplished by launching a larger occulter as a secondary payload to work with existing telescopes such as SOFIA or JWST. The former may allow direct detection of known giant planets, while the latter has the potential to discover Exo-Earths. A full TPF mission would consists of a large occulter working with a dedicated telescope; this can potentially find many terrestrial planets, as well as perform a host of ancillary astronomy investigations such as imaging debris disks and characterizing atmospheres of Jovian planets, as well as making general astrophysics observations. By utilizing the in space servicing capabilities that may be developed for the Exploration program, the lifetime of these occulters may be greatly extended by refueling and repair. In the future, larger occulters (>100 m) could be assembled on orbit. Thus, when coupled with a large telescope, the NWO architecture provides a path towards Lifefinder. NWO is a flexible architecture that allows scalability on all levels to suit the budget available for Exo-Planet Missions.

Lillie, C. F.; Lo, A. S.; Dailey, D.; Glassman, T. M.

2007-06-01

80

Annealing of aromatic polyimide precursors  

NASA Technical Reports Server (NTRS)

A study has been made of the thermal behavior of polyimide precursors: an isomeric pair of crystals of the complex formed by p-phenylenediamine with the separated isomers of the di-isopropyl ester of pyromellitic acid. Specimens of this material were isothermally annealed in the temperature range 120 C to 170 C for periods of time up to 1 week. Although this temperature range is well below that customarily used for imidizations, the working hypothesis was that it would be more likely that a polymer embodying at least part of the precursor structure could be formed if the molecular motion was minimized to that actually required for the formation of the imide linkage. The progress of the annealing was followed by: infrared spectroscopy, differential thermal analysis, powder X-ray diffraction, and thermal gravimetric analysis. Single crystal X-ray analysis of the meta monomer yields a structure of chains of alternating acid and base and suggests that this monomer is amenable to polymerization with a minimum of geometrical disruption.

Wakelyn, N. T.

1975-01-01

81

Precursors for Carbon Nitride Synthesis  

SciTech Connect

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 %.

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

2011-07-15

82

Precursors of the T4 internal peptides.  

PubMed Central

The precursors of the two T4 internal peptides have been identified by in vitro cleavage of individual phage proteins eluted from sodium dodecyl sulfate-acrylamide gels. The precursor of internal peptide VII is p22, the product of T4 gene 22 and an essential component of the morphogenic core. The precursor of peptide II is a protein with a molecular weight of approximately 13,000, whose gene has yet to be defined by mutation. A newly detected protein of approximately 15,000 molecular weight is found to be cleaved and is, therefore, likely to be a component of precursor head structures. Images PMID:864834

Kurtz, M B; Champe, S P

1977-01-01

83

Psychosis in the context of sodium oxybate therapy.  

PubMed

Sodium oxybate (brand name Xyrem) is a sodium salt of gamma-hydroxybutyric acid (GHB), an endogenous CNS depressant, which is an effective treatment of narcolepsy. As a drug of abuse, GHB produces severe psychiatric side effects and withdrawal. However, there are no reports of these effects when using clinically recommended doses. This paper presents a case of a patient who developed altered mental status while taking the recommended dose of sodium oxybate and subsequently became psychotic upon abrupt discontinuation of the medication. It is important for prescribers of sodium oxybate to be aware of the possibility of significant psychiatric side effects of this medication, as well as withdrawal symptoms, even at clinical doses. PMID:22171207

Langford, Jody; Gross, William L

2011-12-15

84

Psychosis in the Context of Sodium Oxybate Therapy  

PubMed Central

Sodium oxybate (brand name Xyrem) is a sodium salt of gamma-hydroxybutyric acid (GHB), an endogenous CNS depressant, which is an effective treatment of narcolepsy. As a drug of abuse, GHB produces severe psychiatric side effects and withdrawal. However, there are no reports of these effects when using clinically recommended doses. This paper presents a case of a patient who developed altered mental status while taking the recommended dose of sodium oxybate and subsequently became psychotic upon abrupt discontinuation of the medication. It is important for prescribers of sodium oxybate to be aware of the possibility of significant psychiatric side effects of this medication, as well as withdrawal symptoms, even at clinical doses. Citation: Langford J; Gross WL. Psychosis in the context of sodium oxybate therapy. J Clin Sleep Med 2011;7(6):665-666. PMID:22171207

Langford, Jody; Gross, William L.

2011-01-01

85

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

PubMed

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

Brown, Stacy D; Melton, Tyler C

2011-01-01

86

Leading time domain seismic precursors  

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

87

Precursors and adjuncts of a lunar base  

NASA Technical Reports Server (NTRS)

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

Burke, J. D.

1988-01-01

88

Method of texturing a superconductive oxide precursor  

DOEpatents

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

DeMoranville, Kenneth L. (Jefferson, MA); Li, Qi (Marlborough, MA); Antaya, Peter D. (Sutton, MA); Christopherson, Craig J. (Worcester, MA); Riley, Jr., Gilbert N. (Marlborough, MA); Seuntjens, Jeffrey M. (Bangau, SG)

1999-01-01

89

The development of migrating muscle precursor cells.  

PubMed

A major subclass of hypaxial muscle groups is derived from long-range migrating precursor cells that delaminate from the dermomyotome. Migrating precursors are generated on particular axial levels only, i.e. occipitally, cervically, and on the levels of the fore and hind limbs. They express the homeobox gene Lbx1, which provides a useful marker for their visualization. In the mouse, migrating precursor cells give rise to muscles of the extremities, the hypoglossal chord, and the diaphragm. We discuss here the development of this migrating lineage, which critically depends on the correct specification of the precursors in the dermomyotome, their delamination and correct migration. Finally, proliferation at the targets is essential to ensure a correct size of the precursor pool and of the muscle that derives thereof. PMID:16977478

Vasyutina, Elena; Birchmeier, Carmen

2006-12-01

90

Error Precursor Analysis Worksheet Page 1 of 6  

E-print Network

Error Precursor Analysis Worksheet Page 1 of 6 Common Error Precursors Error precursors interfere-site conditions can be changed to minimize the chance for error. #12;Error Precursor Analysis Worksheet Page 2;Error Precursor Analysis Worksheet Page 3 of 6 WORK ENVIRONMENT Work Environment Description Conclusion

91

Neural precursors of delayed insight.  

PubMed

The solution of a problem left unresolved in the evening can sometimes pop into mind as a sudden insight after a night of sleep in the following morning. Although favorable effects of sleep on insightful behavior have been experimentally confirmed, the neural mechanisms determining this delayed insight remain unknown. Here, using fMRI, we characterize the neural precursors of delayed insight in the number reduction task (NRT), in which a hidden task structure can be learned implicitly, but can also be recognized explicitly in an insightful process, allowing immediate qualitative improvement in task performance. Normal volunteers practiced the NRT during two fMRI sessions (training and retest), taking place 12 hours apart after a night of sleep. After this delay, half of the subjects gained insight into the hidden task structure ("solvers," S), whereas the other half did not ("nonsolvers," NS). Already at training, solvers and nonsolvers differed in their cerebral responses associated with implicit learning. In future solvers, responses were observed in the superior frontal sulcus, posterior parietal cortex, and the insula, three areas mediating controlled processes and supporting early learning and novice performance. In contrast, implicit learning was related to significant responses in the hippocampus in nonsolvers. Moreover, the hippocampus was functionally coupled with the basal ganglia in nonsolvers and with the superior frontal sulcus in solvers, thus potentially biasing participants' strategy towards implicit or controlled processes of memory encoding, respectively. Furthermore, in solvers but not in nonsolvers, response patterns were further transformed overnight, with enhanced responses in ventral medial prefrontal cortex, an area previously implicated in the consolidation of declarative memory. During retest in solvers, before they gain insight into the hidden rule, significant responses were observed in the same medial prefrontal area. After insight, a distributed set of parietal and frontal areas is recruited among which information concerning the hidden rule can be shared in a so-called global workspace. PMID:20666600

Darsaud, Annabelle; Wagner, Ullrich; Balteau, Evelyne; Desseilles, Martin; Sterpenich, Virginie; Vandewalle, Gilles; Albouy, Geneviève; Dang-Vu, Thanh; Collette, Fabienne; Boly, Melanie; Schabus, Manuel; Degueldre, Christian; Luxen, Andre; Maquet, Pierre

2011-08-01

92

Precursor B Lymphoblastic Lymphoma Involving the Stomach  

PubMed Central

Precursor B lymphoblastic lymphoma is a high-grade neoplasm arising from precursor lymphocytes of B-cell lineage. Extranodal sites such as the skin and bone are often involved, but gastrointestinal lesions of this disease are rarely encountered. Due to the infrequency, macroscopic forms of the gastrointestinal lesions have not been fully described. In this report, we present a case of precursor B lymphoblastic lymphoma involving the stomach, pancreas, bone, and bone marrow. Esophagogastroduodenoscopy showed multiple flat elevated lesions with irregular mucosa in the stomach. PMID:23840980

Kawai, Yoshinari; Yamawaki, Yasuhide; Takata, Katsuyoshi; Yamamoto, Kazuhide

2013-01-01

93

Synthesis and structures of metal chalcogenide precursors  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

94

Precursor B lymphoblastic lymphoma involving the stomach.  

PubMed

Precursor B lymphoblastic lymphoma is a high-grade neoplasm arising from precursor lymphocytes of B-cell lineage. Extranodal sites such as the skin and bone are often involved, but gastrointestinal lesions of this disease are rarely encountered. Due to the infrequency, macroscopic forms of the gastrointestinal lesions have not been fully described. In this report, we present a case of precursor B lymphoblastic lymphoma involving the stomach, pancreas, bone, and bone marrow. Esophagogastroduodenoscopy showed multiple flat elevated lesions with irregular mucosa in the stomach. PMID:23840980

Iwamuro, Masaya; Kawai, Yoshinari; Yamawaki, Yasuhide; Takata, Katsuyoshi; Yamamoto, Kazuhide

2013-01-01

95

A Population of Oligodendrocytes Derived From Multipotent Neural Precursor Cells  

E-print Network

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

Manitoba, University of

96

21 CFR 1308.47 - Control of immediate precursors.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Control of immediate precursors. 1308.47 Section... § 1308.47 Control of immediate precursors. Pursuant to section...the controlled substance of which it is an immediate precursor is placed or any...

2011-04-01

97

21 CFR 1308.47 - Control of immediate precursors.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Control of immediate precursors. 1308.47 Section... § 1308.47 Control of immediate precursors. Pursuant to section...the controlled substance of which it is an immediate precursor is placed or any...

2012-04-01

98

21 CFR 1308.47 - Control of immediate precursors.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Control of immediate precursors. 1308.47 Section... § 1308.47 Control of immediate precursors. Pursuant to section...the controlled substance of which it is an immediate precursor is placed or any...

2013-04-01

99

21 CFR 1308.47 - Control of immediate precursors.  

...2014-04-01 false Control of immediate precursors. 1308.47 Section... § 1308.47 Control of immediate precursors. Pursuant to section...the controlled substance of which it is an immediate precursor is placed or any...

2014-04-01

100

21 CFR 1308.47 - Control of immediate precursors.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Control of immediate precursors. 1308.47 Section... § 1308.47 Control of immediate precursors. Pursuant to section...the controlled substance of which it is an immediate precursor is placed or any...

2010-04-01

101

Long range transport of acid rain precursors  

E-print Network

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 ...

Fay, James A.

1983-01-01

102

Optical Precursor of a Single Photon  

SciTech Connect

We report the direct observation of optical precursors of heralded single photons with step- and square-modulated wave packets passing through cold atoms. Using electromagnetically induced transparency and the slow-light effect, we separate the single-photon precursor, which always travels at the speed of light in vacuum, from its delayed main wave packet. In the two-level superluminal medium, our result suggests that the causality holds for a single photon.

Zhang Shanchao; Chen, J. F.; Liu, Chang; Loy, M. M. T.; Wong, G. K. L.; Du, Shengwang [Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

2011-06-17

103

Hydridosiloxanes as precursors to ceramic products  

DOEpatents

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.

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

1997-06-03

104

Hydridosiloxanes as precursors to ceramic products  

DOEpatents

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.

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

1997-01-01

105

Thermal and crystallization behavior of zirconia precursor used in the solution precursor plasma spray process  

Microsoft Academic Search

Yttria stabilized zirconia (7YSZ) solution precursor has been successfully used in the deposition of high durability thermal\\u000a barrier coatings. In this paper, the thermal and crystallization behaviors of 7YSZ precursor were investigated by TG-DTA,\\u000a FTIR and XRD. The results show that the precursor decomposition and crystallization temperatures greatly depend on heating\\u000a rate e. g. 74C for the crystallization temperature when

Dianying Chen; Eric Jordan; Maurice Gell

2007-01-01

106

75 FR 79404 - Controlled Substances: Established Initial Aggregate Production Quotas for 2011  

Federal Register 2010, 2011, 2012, 2013

...gamma hydroxybutyric acid, heroin, hydrocodone, hydromorphone, marihuana, meperidine...gamma hydroxybutyric acid, heroin, hydrocodone, hydromorphone, marihuana, meperidine...2 g Hydrocodone (for...

2010-12-20

107

Investigating ``Precursor Flows'' in Solar Flares  

NASA Astrophysics Data System (ADS)

Despite some measure of theoretical and predictive success of the electron-heated model of solar flares, observations of low levels of soft X-ray emission prior to the detection of hard X-rays in most flares present a problem for the paradigm, since it suggests some sort of ``preheating'' of the chromospheric plasma before electron acceleration. Particularly troublesome are assertions that plasma flows have been observed prior to hard X-ray emission, because they imply significant and rapid energy input by some agent without leaving a (currently) detectable hard X-ray signature. Given this challenge to a prevailing paradigm, it is imperative to investigate more comprehensively the existence of ``precursor flows'' manifested in the asymmetry of X-ray spectral lines. In this paper, we examine a sample of 50 disk-center flares observed by the Yohkoh Bragg Crystal Spectrometer (BCS) between 1991 and 1993, and determine with the velocity differential emission measure the extent to which ``precursor flows'' occur. We explore specifically the possibility that these ``precursor flows'' are only apparent, arising from the existence of more than one emission region on the solar disk. The spatial separation between regions could cause the emission to be registered by the detector in a wavelength bin that is shifted relative to the line's nominal location, giving rise to line asymmetries. In our sample, we find that only five flares manifest ``precursor flows,'' three of which can be explained definitively by the presence of other active regions. It also appears plausible that the remaining two events can be explained in terms of such spatial effects, although the evidence is more circumstantial. We conclude, therefore, that one can reasonably question the existence of ``precursor flows'' in our sample and that the observations to date cannot contribute decisively to the electron versus proton debate. These results are contrasted with those of Plunkett & Simnett, who identified 14 precursor events in a sample of 35 flares and hence concluded, without further analysis, that protons, rather than electrons, must be the primary energy carriers in flares. Our paper's sample included eight of Plunkett & Simnett's 14 precursor events, and yet our analysis, which employed substantially different methods, identified only one of these eight as a ``precursor'' event. The remaining seven were either troubled by BCS data dropout or failed to exceed the 10% threshold required to classify a flare as a``precursor'' event.

Newton, Elizabeth K.

1997-07-01

108

Germanium nanowire synthesis using solid precursors  

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

109

Nozzle designs with pitch precursor ablatives  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

110

Precursors Prior to Type IIn Supernova Explosions are Common: Precursor Rates, Properties, and Correlations  

NASA Astrophysics Data System (ADS)

There is a growing number of Type IIn supernovae (SNe) which present an outburst prior to their presumably final explosion. These precursors may affect the SN display, and are likely related to poorly charted phenomena in the final stages of stellar evolution. By coadding Palomar Transient Factory (PTF) images taken prior to the explosion, here we present a search for precursors in a sample of 16 Type IIn SNe. We find five SNe IIn that likely have at least one possible precursor event (PTF 10bjb, SN 2010mc, PTF 10weh, SN 2011ht, and PTF 12cxj), three of which are reported here for the first time. For each SN we calculate the control time. We find that precursor events among SNe IIn are common: at the one-sided 99% confidence level, >50% of SNe IIn have at least one pre-explosion outburst that is brighter than 3 × 107 L ? taking place up to 1/3 yr prior to the SN explosion. The average rate of such precursor events during the year prior to the SN explosion is likely >~ 1 yr-1, and fainter precursors are possibly even more common. Ignoring the two weakest precursors in our sample, the precursors rate we find is still on the order of one per year. We also find possible correlations between the integrated luminosity of the precursor and the SN total radiated energy, peak luminosity, and rise time. These correlations are expected if the precursors are mass-ejection events, and the early-time light curve of these SNe is powered by interaction of the SN shock and ejecta with optically thick circumstellar material.

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

2014-07-01

111

Club Drugs (GHB, Ketamine, and Rohypnol)  

MedlinePLUS

... of Addiction Frontiers 2010 A Fresh Look at Dopamine Release and Uptake Connectivity of the Human Brain ... antagonists ketamine and PCP have direct effects on dopamine D2 and serotonin 5-HT2 receptors – Implications for ...

112

ATLANTA OZONE PRECURSOR MONITORING STUDY DATA REPORT  

EPA Science Inventory

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

113

Alternative group V precursors for CVD applications  

NASA Astrophysics Data System (ADS)

The chemical vapor deposition (CVD) techniques used to grow III/V semiconductors films, such as metalorganic vapor phase epitaxy (MOVPE), hydride VPE, chemical beam epitaxy (CBE) and gas source molecular beam epitaxy (GS-MBE), all use hydrides (AsH 3 and PH 3) as the Group V source. However, the hydrides are extremely toxic gases which are stored under high pressure (200-2000 psi). To reduce the safety hazards associated with these gases, alternative Group V precursors have been investigated. Organoarsenic and phosphorous compounds have received the most attention as replacements for AsH 3 and PH 3 because they are typically low vapor pressure liquids, and thus present significantly lower exposure risks than the hydrides. For AsH 3 these have included the methyl, ethyl and butyl-based derivatives RnAsH 3- n, with varying degrees ( n = 1-3) of hydrogen atom substitution. In this paper the growth properties, thermochemistry and toxicity of the various alkylarsine precursors are compared with arsine. Data are presented on the impact of the thermochemistry of these compounds on film electrical properties, and on the effects of precursor composition and purity on overall film quality. The suitability of alternative As-precursors for device applications is demonstrated, and selection criteria are presented for the most effective alkylarsine compound for a particular CVD growth process.

Lum, R. M.; Klingert, J. K.

1991-01-01

114

Subcellular compartmentation of glutathione and glutathione precursors  

Microsoft Academic Search

Selective antibodies were used to assess the cellular and subcellular localization of glutathione, and the glutathione precursors %-glutamylcysteine, glutamate, and cysteine, in neuronal (photoreceptors) and non-neuronal (pigment epithelial cells and Müller cells) cell types in the outer retina of the guinea pig. In each cell type the highest level of glutathione immunoreactivity occurred in the mitochondria. The labeling density in

Dominik Huster; Ole P. Hjelle; Finn-Mogens Haug; Erlend A. Nagelhus; Winfried Reichelt; O. P. Ottersen

1998-01-01

115

Innate lymphoid cells: of precursors and products….  

PubMed

Recent reports have identified committed innate lymphoid cell (ILC) precursors and tissue-resident ILC subsets that have unique functional attributes. Taken together, these studies provide a framework for understanding how distinct ILCs are generated during hematopoiesis and further suggest additional parallels between models of ILC and T helper cell differentiation. PMID:24937286

Serafini, Nicolas; Xu, Wei; Di Santo, James P

2014-06-16

116

Superconductor precursor mixtures made by precipitation method  

DOEpatents

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

Bunker, Bruce C. (Albuquerque, NM); Lamppa, Diana L. (Albuquerque, NM); Voigt, James A. (Albuquerque, NM)

1989-01-01

117

The amyloid precursor protein: beyond amyloid  

Microsoft Academic Search

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

Hui Zheng; Edward H Koo

2006-01-01

118

ARCHIVAL REPORT Mifepristone Alters Amyloid Precursor Protein  

E-print Network

-terminal cleavage of APP that prevents it being cleaved by a- or b-secretase, thereby precluding Ab generation in the central nervous system; this cleavage and the production of the 17-kDa APP fragment was generated precursor protein (APP) processing revealed concomitant decreases in both APP C-terminal fragments C99 and C

Brody, James P.

119

Detection of Chemical Precursors of Explosives  

NASA Technical Reports Server (NTRS)

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.

Li, Jing

2012-01-01

120

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

NASA Astrophysics Data System (ADS)

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 × B force on the inner wires. Closely spaced arrays of 6-16 wires with outer diameter of 16 mm and with gaps of ?R = 0.25-1 mm were tested. 6-8-wire arrays with a gap of ?R = 0.4-1 mm imploded without precursor, but precursor was present in loads with 12-16 wires and ?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.

Papp, D.; Ivanov, V. V.; Jones, B.; Haboub, A.; Anderson, A. A.; Altemara, S. D.; Talbot, B. R.

2012-09-01

121

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

SciTech Connect

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.

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

122

Biochar as a precursor of activated carbon.  

PubMed

Biochar was evaluated as a precursor of activated carbon. This product was produced by chemical activation using potassium hydroxide. The effects of operating conditions of activation process, such as temperature, activating agent to biochar mass ratio, and nitrogen flow rate, on the textural and chemical properties of the product were investigated. Activated carbon produced by this method has internal surface area at least 50 times than that of the precursor and is highly microporous, which is also confirmed by scanning electron microscopy analysis. Fourier-transform infrared spectroscopy analysis showed development of aromatization in the structure of activated carbon. X-ray diffraction data indicated the formation of small, two-dimensional graphite-like structure at high temperatures. Thermogravimetric study showed that when potassium hydroxide to biochar mass ratio was more than one, the weight loss decreased. PMID:16915686

Azargohar, R; Dalai, A K

2006-01-01

123

Biochar as a precursor of activated carbon.  

PubMed

Biochar was evaluated as a precursor of activated carbon. This product was produced by chemical activation using potassium hydroxide. The effects of operating conditions of activation process, such as temperature, activating agent to biochar mass ratio, and nitrogen flow rate, on the textural and chemical properties of the product were investigated. Activated carbon produced by this method has internal surface area at least 50 times than that of the precursor and is highly microporous, which is also confirmed by scanning electron microscopy analysis. Fourier-transform infrared spectroscopy analysis showed development of aromatization in the structure of activated carbon. X-ray diffraction data indicated the formation of small, two-dimensional graphite-like structure at high temperatures. Thermogravimetric study showed that when potassium hydroxide to biochar mass ratio was more than one, the weight loss decreased. PMID:18563652

Azargohar, R; Dalai, A K

2006-03-01

124

Electromagnetic Whistler Precursors at Supercritical Interplanetary Shocks  

NASA Technical Reports Server (NTRS)

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.

Wilson, L. B., III

2012-01-01

125

Studies of Enzymes in Mitochondrial DNA Precursor Synthesis  

E-print Network

Studies of Enzymes in Mitochondrial DNA Precursor Synthesis Regulatory Mechanisms for Human;Studies of Enzymes in Mitochondrial DNA Precursor Synthesis - Regulatory Mechanisms for Human Thymidine Kinase 2 and Deoxyguanosine Kinase Abstract As important enzymes in mitochondrial nucleotide salvage

126

40 CFR 766.38 - Reporting on precursor chemical substances.  

Code of Federal Regulations, 2010 CFR

...false Reporting on precursor chemical substances. 766.38 Section 766.38 Protection...PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT DIBENZO-PARA-DIOXINS...38 Reporting on precursor chemical substances. (a) Identification of...

2010-07-01

127

40 CFR 766.38 - Reporting on precursor chemical substances.  

Code of Federal Regulations, 2011 CFR

...false Reporting on precursor chemical substances. 766.38 Section 766.38 Protection...PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT DIBENZO-PARA-DIOXINS...38 Reporting on precursor chemical substances. (a) Identification of...

2011-07-01

128

40 CFR 766.38 - Reporting on precursor chemical substances.  

Code of Federal Regulations, 2013 CFR

...false Reporting on precursor chemical substances. 766.38 Section 766.38 Protection...PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT DIBENZO-PARA-DIOXINS...38 Reporting on precursor chemical substances. (a) Identification of...

2013-07-01

129

40 CFR 766.38 - Reporting on precursor chemical substances.  

Code of Federal Regulations, 2012 CFR

...false Reporting on precursor chemical substances. 766.38 Section 766.38 Protection...PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT DIBENZO-PARA-DIOXINS...38 Reporting on precursor chemical substances. (a) Identification of...

2012-07-01

130

Precursors to radiopharmaceutical agents for tissue imaging  

DOEpatents

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

Srivastava, Prem C. (Oak Ridge, TN); Knapp, Jr., Furn F. (Oak Ridge, TN)

1988-01-01

131

Biochar as a precursor of activated carbon  

Microsoft Academic Search

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

R. Azargohar; A. K. Dalai

2006-01-01

132

Biochar As a Precursor of Activated Carbon  

Microsoft Academic Search

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

R. Azargohar; A. K. Dalai

133

Endocrine Precursor Lesions of Gastroenteropancreatic Neuroendocrine Tumors  

Microsoft Academic Search

This review focuses on precursor lesions of gastrointestinal and pancreatic neuroendocrine tumors (GEP-NETs). There are three\\u000a conditions that are associated with hyperplastic changes in endocrine cells preceding GEP-NETs: autoimmune chronic atrophic\\u000a gastritis or multiple endocrine neoplasia type 1 (MEN1) with gastric enterochromaffin-like (ECL) cell hyperplasia; MEN1 with\\u000a gastrin and somatostatin cell hyperplasia in the duodenum and glucagon cell hyperplasia in

Günter Klöppel; Martin Anlauf; Aurel Perren

2007-01-01

134

A committed precursor to innate lymphoid cells.  

PubMed

Innate lymphoid cells (ILCs) specialize in the rapid secretion of polarized sets of cytokines and chemokines to combat infection and promote tissue repair at mucosal barriers. Their diversity and similarities with previously characterized natural killer (NK) cells and lymphoid tissue inducers (LTi) have prompted a provisional classification of all innate lymphocytes into groups 1, 2 and 3 solely on the basis of cytokine properties, but their developmental pathways and lineage relationships remain elusive. Here we identify and characterize a novel subset of lymphoid precursors in mouse fetal liver and adult bone marrow that transiently express high amounts of PLZF, a transcription factor previously associated with NK T cell development, by using lineage tracing and transfer studies. PLZF(high) cells were committed ILC progenitors with multiple ILC1, ILC2 and ILC3 potential at the clonal level. They excluded classical LTi and NK cells, but included a peculiar subset of NK1.1(+)DX5(-) 'NK-like' cells residing in the liver. Deletion of PLZF markedly altered the development of several ILC subsets, but not LTi or NK cells. PLZF(high) precursors also expressed high amounts of ID2 and GATA3, as well as TOX, a known regulator of PLZF-independent NK and LTi lineages. These findings establish novel lineage relationships between ILC, NK and LTi cells, and identify the common precursor to ILCs, termed ILCP. They also reveal the broad, defining role of PLZF in the differentiation of innate lymphocytes. PMID:24509713

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

2014-04-17

135

Procollagen I-expressing renin cell precursors.  

PubMed

Renin-expressing cells in the kidney normally appear as mural cells of developing preglomerular vessels and finally impose as granulated juxtaglomerular cells in adult kidneys. The differentiation of renin-expressing cells from the metanephric mesenchyme in general and the potential role of special precursor stages in particular is not well understood. Therefore, it was the aim of this study to search for renin cell precursors in the kidney. As an experimental model, we used kidneys of aldosterone synthase-deficient mice, which display a prominent compensatory overproduction of renin cells that are arranged in multilayered perivascular cell clusters. We found that the perivascular cell clusters contained two apparently distinct cell types, one staining positive for renin and another one staining positive for type I procollagen (PC1). It appeared as if PC1 and renin expression were inversely related at the cellular level. The proportion of renin-positive to PC1-positive cells in the clusters was inversely linked to the rate of salt intake, as was overall renin expression. Our findings suggest that the cells in the perivascular cell clusters can reversibly switch between PC1 and renin expression and that PC1-expressing cells might be precursors of renin cells. A few of those PC1-positive cells were found also in adult wild-type kidneys in the juxtaglomerular lacis cell area, in which renin expression can be induced on demand. PMID:23761669

Karger, Christian; Kurtz, Felix; Steppan, Dominik; Schwarzensteiner, Ilona; Machura, Katharina; Angel, Peter; Banas, Bernhard; Risteli, Juha; Kurtz, Armin

2013-08-01

136

Cellular Kinetics of Perivascular MSC Precursors  

PubMed Central

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

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

2013-01-01

137

Histopathology of cervical precursor lesions and cancer.  

PubMed

The most frequent types of cervical cancer are squamous-cell carcinoma and adenocarcinoma, which develop from the distinctive precursor lesions cervical intraepithelial neoplasia (CIN) / squamous intraepithelial lesion (SIL), and adenocarcinoma in situ (AIS), respectively. Their tumorigenesis is HPV-related. High-risk HPV (e.g., types 16 and 18) is integrated into the genome and leads to tumor progression. Cytological screening leads to detection of precursors and their mimics. P16 and Ki-67 immunohistochemistry assists in the histological differential diagnosis of precursors to reactive and metaplastic epithelium. For invasive cervical carcinoma, stage is the strongest prognostic factor. Per definition, microinvasive (pT1a1 / pT1a2) carcinoma is diagnosed histologically on cone biopsies and treated less radically. The distinction between adenocarcinomas of the cervix and endometrial adenocarcinomas is important and can be supported by immunohistochemistry (e.g., ER, p16, CEA, and vimentin) and HPV in-situ hybridization. The rarer adenoid-basal and neuroendocrine carcinomas are less frequently HPV-related. PMID:22131112

Lax, Sigurd

2011-09-01

138

Cellular kinetics of perivascular MSC precursors.  

PubMed

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

Chen, William C W; Park, Tea Soon; Murray, Iain R; Zimmerlin, Ludovic; Lazzari, Lorenza; Huard, Johnny; Péault, Bruno

2013-01-01

139

Effects of detergents on ribosomal precursor subunits of Bacillus megaterium.  

PubMed

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

Body, A; Brownstein, B H

1978-01-01

140

Effects of Detergents on Ribosomal Precursor Subunits of Bacillus megaterium  

PubMed Central

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

Body, Barbara A.; Brownstein, Bernard H.

1978-01-01

141

Amyloid precursor protein and neural development.  

PubMed

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

Nicolas, Maya; Hassan, Bassem A

2014-07-01

142

The Mars 2001 Athena Precursor Experiment (APEX)  

NASA Technical Reports Server (NTRS)

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

Squyres, S. W.; Arvidson, R.; Bell, J. F., III; Carr, M.; Christensen, P.; DesMarais, D.; dUston, C.; Economou, T.; Gorevan, S.; Klingelhoefer, G.

1999-01-01

143

The development of autonomy and superego precursors.  

PubMed

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

Blum, E J; Blum, H P

1990-01-01

144

Ascorbate as a Biosynthetic Precursor in Plants  

PubMed Central

Background and Aims l-Ascorbate (vitamin C) has well-documented roles in many aspects of redox control and anti-oxidant activity in plant cells. This Botanical Briefing highlights recent developments in another aspect of l-ascorbate metabolism: its function as a precursor for specific processes in the biosynthesis of organic acids. Scope The Briefing provides a summary of recent advances in our understanding of l-ascorbate metabolism, covering biosynthesis, translocation and functional aspects. The role of l-ascorbate as a biosynthetic precursor in the formation of oxalic acid, l-threonic acid and l-tartaric acid is described, and progress in elaborating the mechanisms of the formation of these acids is reviewed. The potential conflict between the two roles of l-ascorbate in plant cells, functional and biosynthetic, is highlighted. Conclusions Recent advances in the understanding of l-ascorbate catabolism and the formation of oxalic and l-tartaric acids provide compelling evidence for a major role of l-ascorbate in plant metabolism. Combined experimental approaches, using classic biochemical and emerging ‘omics’ technologies, have provided recent insight to previously under-investigated areas. PMID:17098753

Debolt, Seth; Melino, Vanessa; Ford, Christopher M.

2007-01-01

145

Neutron-powered precursors of kilonovae  

E-print Network

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 ~1e-4 Msun) 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 beta-decay of these free neutrons in the outermost ejecta powers a `precursor' to the main kilonova emission, which peaks on a timescale of a few hours following merger at U-band magnitude ~22 (for an assumed distance of 200 Mpc). The high luminosity and blue colors of the neutron precursor render it a potentially important counterpart to the gravitational wave source, t...

Metzger, Brian D; Goriely, Stephane; Kasen, Daniel

2014-01-01

146

The Functions of Mammalian Amyloid Precursor Protein and Related Amyloid Precursor-Like Proteins  

Microsoft Academic Search

It is well established that proteolytic processing of the ?-amyloid precursor protein (APP) generates ?-amyloid which plays a central role in the pathogenesis of Alzheimer’s disease. In contrast, the physiological role of APP and the question of whether a loss of these functions contributes to Alzheimer’s disease are still unclear. For a long time, the characterization of APP functions was

Brigitte Anliker; Ulrike Müller

2006-01-01

147

Pharmacologic rescue of lethal seizures in mice deficient in succinate semialdehyde dehydrogenase.  

PubMed

Succinate semialdehyde dehydrogenase (ALDH5A1, encoding SSADH deficiency is a defect of 4-aminobutyric acid (GABA) degradation that manifests in humans as 4-hydroxybutyric (gamma-hydroxybutyric, GHB) aciduria. It is characterized by a non-specific neurological disorder including psychomotor retardation, language delay, seizures, hypotonia and ataxia. The current therapy, vigabatrin (VGB), is not uniformly successful. Here we report the development of Aldh5a1-deficient mice. At postnatal day 16-22 Aldh5a1-/- mice display ataxia and develop generalized seizures leading to rapid death. We observed increased amounts of GHB and total GABA in urine, brain and liver homogenates and detected significant gliosis in the hippocampus of Aldh5a1-/- mice. We found therapeutic intervention with phenobarbital or phenytoin ineffective, whereas intervention with vigabatrin or the GABAB receptor antagonist CGP 35348 (ref. 2) prevented tonic-clonic convulsions and significantly enhanced survival of the mutant mice. Because neurologic deterioration coincided with weaning, we hypothesized the presence of a protective compound in breast milk. Indeed, treatment of mutant mice with the amino acid taurine rescued Aldh5a1-/- mice. These findings provide insight into pathomechanisms and may have therapeutic relevance for the human SSADH deficiency disease and GHB overdose and toxicity. PMID:11544478

Hogema, B M; Gupta, M; Senephansiri, H; Burlingame, T G; Taylor, M; Jakobs, C; Schutgens, R B; Froestl, W; Snead, O C; Diaz-Arrastia, R; Bottiglieri, T; Grompe, M; Gibson, K M

2001-10-01

148

The solution precursor plasma spray processing of nanomaterials  

Microsoft Academic Search

Solution precursor plasma spray (SPPS) synthesis is a simple, single-step, and rapid technique for synthesizing nano-ceramic\\u000a materials from solution precursors. This innovative method uses molecularly mixed precursors as liquids, avoiding a separate\\u000a processing method for the preparation of powders and enabling the synthesis of a wide range of metal oxide powders and coatings.\\u000a Also, this technique is considered to be

E. Brinley; K. S. Babu; S. Seal

2007-01-01

149

Amyloid Precursor Protein Processing and Alzheimer's Disease  

PubMed Central

Alzheimer’s disease (AD), the leading cause of dementia worldwide, is characterized by the accumulation of the ?-amyloid peptide (A?) within the brain along with hyperphosphorylated and cleaved forms of the microtubule-associated protein tau. Genetic, biochemical, and behavioral research suggest that physiologic generation of the neurotoxic A? peptide from sequential amyloid precursor protein (APP) proteolysis is the crucial step in the development of AD. APP is a single-pass transmembrane protein expressed at high levels in the brain and metabolized in a rapid and highly complex fashion by a series of sequential proteases, including the intramembranous ?-secretase complex, which also process other key regulatory molecules. Why A? accumulates in the brains of elderly individuals is unclear but could relate to changes in APP metabolism or A? elimination. Lessons learned from biochemical and genetic studies of APP processing will be crucial to the development of therapeutic targets to treat AD. PMID:21456963

O'Brien, Richard J.; Wong, Philip C.

2011-01-01

150

Damage precursor measurements on UV optical coatings  

NASA Astrophysics Data System (ADS)

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

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

1995-07-01

151

Filler/ Polycarbosilane Systems as CMC Matrix Precursors  

NASA Technical Reports Server (NTRS)

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.

Hurwitz, Frances I.

1998-01-01

152

MOCVD OF YSZ COATINGS USING ?-DIKETONATE PRECURSORS  

SciTech Connect

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

Varanasi, Venu G [ORNL; Besmann, Theodore M [ORNL; Hyde, Robin L. [Oak Ridge National Laboratory (ORNL); Payzant, E Andrew [ORNL; Anderson, Timothy J [University of Florida

2009-01-01

153

Precursors to glycogen in ovine fetuses  

SciTech Connect

Postprandial hepatic glycogenesis in the adult animal is now felt to proceed largely through gluconeogenic pathways rather than directly from glucose. The ovine fetus, like the mature sheep, lacks specific hepatic glucokinase. Therefore, the authors examined the role of lactate as a fetal glycogenic precursor in seven chronically catheterized 125-day sheep fetuses. Fetuses were infused with L-(U-{sup 14}C)lactate and D-(3-{sup 3}H)glucose, while maternal glucose was maintained at 50 mg/dl. Mean fetal hepatic glycogen specific activity ({mu}Ci/mg {times} 10{sup 3}) was 0.82 {plus minus} 0.08 for {sup 14}C and 2.6 {plus minus} 0.4 for {sup 3}H, whereas fetal renal glycogen specific activity was 0.46 {plus minus} 0.22 for {sup 14}C and 0.78 {plus minus} 0.16 for {sup 3}H. In contrast, ({sup 14}C)glucose specific activity was undetectable in blood and mean ({sup 3}H)glucose specific activity was 8.9 {plus minus} 1.3 {mu}Ci/mg {times} 10{sup 3}. The least detectable specific activity of ({sup 14}C)glucose did not differ significantly from the ({sup 14}C)glycogen enrichment in liver, whereas ({sup 3}H)glucose specific activity was significantly greater than ({sup 3}H)glycogen enrichment. The authors conclude that glycogenesis from glucose is partly through the indirect gluconeogenic route and that lactate may be a glycogenic precursor in the ovine fetus.

Levitsky, L.L.; Paton, J.B.; Fisher, D.E. (Univ. of Chicago, IL (USA))

1988-11-01

154

Diamond films grown from fullerene precursors  

SciTech Connect

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.

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

1995-07-01

155

[Chemical submission: a literature review].  

PubMed

The aim of this review is to describe the present knowledge about chemical submission. The number of scientific publications on this phenomenon has increased over the last 10 years. Perpetrators choose drugs which act rapidly, produce desinhibition, sedation, and anterograde amnesia during the abuse. Ethanol and benzodiazepines are the most frequently used. A few drugs, including flunitrazepam and gamma-hydroxybutyric acid (GHB), have received widespread media coverage. Toxicological investigations on blood, urine or hair samples allow to detect the substance used. Every effort should be made to collect appropriate specimens as quickly as possible. Gas chromatography-mass spectrometry is at present the most appropriate analytical method to detect these drugs in a biological specimen. PMID:16886708

Saint-Martin, Pauline; Furet, Yves; O'Byrne, Patrick; Bouyssy, Marie; Paintaud, Gilles; Autret-Leca, Elisabeth

2006-01-01

156

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

PubMed Central

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

Weir, E

2000-01-01

157

A hydrophilic interaction liquid chromatography electrospray tandem mass spectrometry method for the simultaneous determination of ?-hydroxybutyrate and its precursors in forensic whole blood.  

PubMed

A liquid-chromatography-tandem-mass-spectrometry method using pneumatically assisted electrospray ionisation (LC-ESI-MS/MS) was developed for the simultaneous determination of ?-hydroxybutyric acid (GHB), ?-butyrolactone (GBL) and 1,4-butanediol (1,4-BD) in human ante-mortem and post-mortem whole blood. The blood proteins were precipitated using a mixture of methanol and acetonitrile, and the extract was cleaned-up by passage through a polymeric strong cation exchange sorbent. Separation of the analytes and their structural isomers was obtained using a column with a zwitterionic stationary phase. Matrix-matched calibrants, combined with isotope dilution, were used for quantitative analysis. GHB was determined in both positive and negative ion modes. The relative intra-laboratory reproducibility standard deviations were better than 10% and 6% for blood samples at concentrations of 2 mg/L and 20-150 mg/L, respectively. The mean true extraction recoveries were 80% for GHB and greater than 90% for GBL and 1,4-BD at concentration levels of 20-50 mg/L. The limits of detection were approximately 0.5 mg/L for GHB and GBL, and 0.02 mg/L for 1,4-BD in ante-mortem blood. The corresponding lower limits of quantification were less than 1 mg/L for GHB and GBL, and less than 0.1 mg/L for 1,4-BD. GBL was unstable in whole blood freshly preserved with a sodium fluoride oxalate mixture, but the stability could be improved significantly by preservation with a sodium fluoride citrate EDTA mixture. PMID:22917943

Sørensen, Lambert K; Hasselstrøm, Jørgen B

2012-10-10

158

Hydrodeoxygenation of coal using organometallic catalyst precursors  

NASA Astrophysics Data System (ADS)

The objective of this dissertation was to determine the desirability of organometallic compounds for the hydrodeoxygenation (HDO) of coal during liquefaction. The primary focus of this study was the removal of phenol-like compounds from coal liquids for the production of a thermally stable jet fuel. Investigation of the HDO ability of an organometallic compound containing both cobalt and molybdenum (CoMo-T2) was achieved using a combination of model compound and coal experiments. Model compounds were chosen representing four oxygen functional groups present in a range of coals. Electron density and bond order calculations were performed for anthrone, dinaphthyl ether, xanthene, di-t-butylmethylphenol, and some of their derivatives to ascertain a potential order of hydrogenolysis and hydrogenation reactivity for these compounds. The four model compounds were then reacted with CoMo-T2, as well as ammonium tetrathiomolybdate (ATTM). Products of reaction were grouped as compounds that had undergone deoxygenation, those that had aromatic rings reduced, those that were products of both reaction pathways, and those produced through other routes. ATTM had an affinity for both reaction types. Its reaction order for the four model compounds with respect to deoxygenated compounds was the same as that estimated from electron density calculations for hydrogenolysis reactivity. CoMo-T2 appeared to show a preference toward hydrogenation, although deoxygenated products were still achieved in similar, or greater, yields, for almost all the model compounds. The reactivity order achieved for the four compounds with CoMo-T2 was similar to that estimated from bond order calculations for hydrogenation reactivity. Three coals were selected representing a range of coal ranks and oxygen contents. DECS-26 (Wyodak), DECS-24 (Illinois #6), and DECS-23 (Pittsburgh #8) were analyzed by CPMAS 13C NMR and pyrolysis-GC-MS to determine the functional groups comprising the oxygen content of these coals. Trends within the data were similar to those reported by other authors. Based on the conclusions from both the model compound studies and the coal analysis, predictions were made of the catalyst precursors' performance in the HDO of the three selected coals. It was concluded that CoMo-T2 is a desirable catalyst precursor for the HDO of coals (particularly low-rank coals), but that an optimum set of conditions must be determined to take full advantage of its HDO ability. (Abstract shortened by UMI.)

Kirby, Stephen R.

2002-04-01

159

Topographical and Functional Properties of Precursors to Severe Problem Behavior  

ERIC Educational Resources Information Center

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…

Fahmie, Tara A.; Iwata, Brian A.

2011-01-01

160

Precursors to Aggression Are Evident by 6 Months of Age  

ERIC Educational Resources Information Center

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…

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

161

Effect of molybdenum disulfide precursor on catalyst activity  

Microsoft Academic Search

Molybdenum disulfide is a well recognized coal liquefaction catalyst. Recently, work has concentrated on unsupported forms of the catalyst commonly referred to as dispersed catalysts. The active form of the catalyst is believed to have a stoichiometry at or near MoSâ regardless of the precursor. The higher activities found for some precursors are usually attributed to a higher degree of

K. T. Schroeder; B. C. Bockrath; H. Davis; R. D. Miller

1990-01-01

162

TECHNICAL ASSISTANCE DOCUMENT FOR SAMPLING AND ANALYSIS OF OZONE PRECURSORS  

EPA Science Inventory

This document contains guidance and discussion on methods applicable to the proposed revisions to Title 40 Part 58 of the Code of Federal Regulations. he proposed revisions pertain to the enhanced monitoring of ozone precursors and meteorological monitoring. he precursors address...

163

Endogenous Nkx2.2+ oligodendrocyte precursor cells fail  

E-print Network

Endogenous Nkx2.2+ /Olig2+ oligodendrocyte precursor cells fail to remyelinate the demyelinated of endogenous oligodendrocyte precursor cells (OPCs) following ethidium bromide (EB)-induced demyelination proliferative NG2+ cells within the lesion was observed, none of which expressed the oligodendrocyte lineage

Harkema, Susan

164

Prospective assessment of intraoperative precursor events during cardiac surgery  

Microsoft Academic Search

Objective: Increasing attention has been afforded to the ubiquity of medical error and associated adverse events in medicine. There remains little data on the frequency and nature of precursor events in cardiac surgery, and we sought to characterize this. Methods: Detailed, anonymous information regarding intraoperative precursor events (which may result in adverse events) was collected prospectively from six key members

Daniel R. Wong; Thomas J. Vander Salm; Imtiaz S. Ali; Arvind K. Agnihotri; Richard M. J. Bohmer; David F. Torchiana

2006-01-01

165

A Procedure for Identifying Precursors to Problem Behavior  

ERIC Educational Resources Information Center

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

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

2009-01-01

166

Identification, selection, and enrichment of cardiomyocyte precursors.  

PubMed

The large-scale production of cardiomyocytes is a key step in the development of cell therapy and tissue engineering to treat cardiovascular diseases, particularly those caused by ischemia. The main objective of this study was to establish a procedure for the efficient production of cardiomyocytes by reprogramming mesenchymal stem cells from adipose tissue. First, lentiviral vectors expressing neoR and GFP under the control of promoters expressed specifically during cardiomyogenesis were constructed to monitor cell reprogramming into precardiomyocytes and to select cells for amplification and characterization. Cellular reprogramming was performed using 5'-azacytidine followed by electroporation with plasmid pOKS2a, which expressed Oct4, Sox2, and Klf4. Under these conditions, GFP expression began only after transfection with pOKS2a, and less than 0.015% of cells were GFP(+). These GFP(+) cells were selected for G418 resistance to find molecular markers of cardiomyocytes by RT-PCR and immunocytochemistry. Both genetic and protein markers of cardiomyocytes were present in the selected cells, with some variations among them. Cell doubling time did not change after selection. Together, these results indicate that enrichment with vectors expressing GFP and neoR under cardiomyocyte-specific promoters can produce large numbers of cardiomyocyte precursors (CMPs), which can then be differentiated terminally for cell therapy and tissue engineering. PMID:23853770

Zanetti, Bianca Ferrarini; Gomes, Walter José; Han, Sang Won

2013-01-01

167

Amyloid precursor protein in aged nonhuman primates.  

PubMed Central

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

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

1991-01-01

168

Bacterial Cellular Materials as Precursors of Chloroform  

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

169

A Fission-Powered Interstellar Precursor Mission  

SciTech Connect

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

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

1998-10-28

170

Precursor and processing conditions to make dense ceramic coatings using the solution precursor plasma spraying process  

NASA Astrophysics Data System (ADS)

The objective of this research is to determine the precursor and processing conditions to produce nanograined ceramic coatings with high density and hardness using the Solution Precursor Plasma Spray (SPPS) process. These dense coatings would find potential applications as optical ceramics, wear resistant coatings and bioactive coatings. Basic operating principles needed to create relatively dense coatings using the SPPS process have been discovered. These principles were then used to produce two new precursors and associated processing methods. It has been shown that dense coatings can be best produced if deposits arriving at the substrate are fully Incited. Multiple factors have been experimentally identified that provide dense coatings, including: (1) high solution concentration: (2) low melting temperature compositions; (3) large diameter gun nozzles: (4) high gun power and low liquid feed rates, (5) better entrainment of the droplets in the hot part of the plasma jet. Based on these principles of dense coating formation, dense eutectic Al2O3-YSZ SPPS coatings were produced. The as-deposited coating has 95.6% density and hardness of 11.8 GPa. The thermal stability of as-sprayed dense eutectic Al2O3-7YSZ coatings was examined. High temperature heat treatments of the coating show that both the phase and nano-grain structure are very stable. The nanocomposite Al 2O3-7YSZ coatings are highly grain growth resistant due to the increased diffusion path of species along interphase boundaries. The reproducibility of the principles to make dense ceramic coatings was successfully demonstrated by deposition of a low melting point TiO 2 coating that has desirable biological properties. A dense TiO 2 coating (96%) with a hardness of 7.6 GPa was achieved. The conditions for making dense coatings have been identified. The discovery and demonstration of basic principles for making dense SPPS coatings is a fundamental advancement of the state of the art for SPPS coating technology.

Chen, Dianying

171

PHOTOSPHERIC RADIUS EXPANSION IN SUPERBURST PRECURSORS FROM NEUTRON STARS  

SciTech Connect

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

Keek, L., E-mail: keek@nscl.msu.edu [National Superconducting Cyclotron Laboratory, Department of Physics and Astronomy, and Joint Institute for Nuclear Astrophysics, Michigan State University, East Lansing, MI 48824 (United States)

2012-09-10

172

Biosynthesis of Tetrapyrrole Pigment Precursors 1  

PubMed Central

The universal tetrapyrrole precursor ?-aminolevulinic acid (ALA) is formed from glutamate (Glu) in algae and higher plants. In the postulated reaction sequence, Glu-tRNA is produced by a Glu-tRNA synthetase, and the product serves as a substrate for a reduction step catalyzed by a pyridine nucleotide-requiring Glu-tRNA dehydrogenase. The reduced intermediate is then converted into ALA by a transaminase. An RNA and three enzyme fractions required for ALA formation from Glu have been isolated from soluble Chlorella extracts. The recombined fractions catalyzed ALA production from Glu or Glu-tRNA. The fraction containing the synthetase produced Glu-tRNA from Glu and tRNA in the presence of ATP and Mg2+. The isolated product of this reaction served as substrate for ALA production by the partially reconstituted enzyme system lacking the synthetase fraction and incapable of producing ALA from Glu. The production of ALA from Glu-tRNA by this partially reconstituted system did not require free Glu or ATP, and was not affected by added ATP. These results show that (a) free Glu-tRNA is an intermediate in the formation of ALA from Glu, (b) ATP is required only in the first step of the reaction sequence, and NADPH only in a later step, (c) Glu-tRNA production is the essential reaction catalyzed by one of the enzyme fractions, (d) this enzyme fraction is active in the absence of the other enzymes and is not required for activity of the others. The specific Glu-tRNA synthetase required for ALA formation has an approximate molecular weight of 73,000 ± 5,000 as determined by Sephadex G-100 gel filtration and native polyacrylamide gel electrophoresis. Other Glu-tRNA synthetases were present in the cell extracts but were ineffective in the the ALA-forming process. Images Fig. 3 Fig. 6 PMID:16666399

Avissar, Yael J.; Beale, Samuel I.

1988-01-01

173

PRECOMBUSTION REMOVAL OF HAZARDOUS AIR POLLUTANT PRECURSORS  

SciTech Connect

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.

Unknown

2000-10-09

174

Methods for forming particles from single source precursors  

DOEpatents

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.

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

2011-08-23

175

Molybdenum nitride fibers or tubes via ammonolysis of polysulfide precursor  

NASA Astrophysics Data System (ADS)

Millimeter-sized molybdenum nitride (MoN), in the forms of fiber-like prisms or hollow tubes, has been successfully synthesized via thermal ammonolysis of molybdenum polysulfide precursor. The initial morphology of the precursor is well preserved in the final product. This method could be expanded to preparation of other fiber-like nonmetal ceramics without addition of template. The polysulfide precursor (abbreviated to PS), hydrothermally prepared at 30°C (PS1) or 150°C (PS2), was characterized by various methods for better comprehension of the sulfide-nitride topotactic conversion model.

Wang, Shutao; Zhang, Zude; Zhang, Yange; Qian, Yitai

2004-08-01

176

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

E-print Network

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

Harkema, Susan

177

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

E-print Network

Transportation Center Seminar........ "The Panama Canal as Precursor" Aaron J. Gellman Professor of Transportation The Transportation Center & Kellogg School of Management Northwestern University; Advisory:30 pm Location: Transportation Center, Chambers Hall Lower Level, 600 Foster St., Evanston Professor

Bustamante, Fabián E.

178

Chemical preparation and shock wave compression of carbon nitride precursors  

SciTech Connect

Two synthetic routes have been developed to produce high-molecular-weight organic precursors containing a high weight fraction of nitrogen. One of the precursors is a pyrolysis residue of melamine-formaldehyde resin. The second precursor is the byproduct of an unusual low-temperature combustion reaction of tetrazole and its sodium salt. These precursors have been shock compressed under typical conditions for diamond and wurtzite boron nitride synthesis in an attempt to recover a new ultrahard carbon nitride. The recovered material has been analyzed by X-ray diffraction, FTIR, and Raman microprobe analysis. Diamond is present in the recovered material. This diamond is well ordered relative to diamond shock synthesized from carbonaceous starting materials.

Wixon, M.R. (KMS Fusion, Inc., Ann Arbor, MI (USA))

1990-07-01

179

Precursor composites for oxygen dispersion hardened silver sheathed superconductor composites  

DOEpatents

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

Podtburg, E.R.

1999-06-22

180

Precursor composites for oxygen dispersion hardened silver sheathed superconductor composites  

DOEpatents

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

Podtburg, Eric R. (Natick, MA)

1999-01-01

181

Bone marrow accessory cells regulate human bone precursor cell development  

Microsoft Academic Search

ObjectiveMuch remains to be learned about the intimate relationship between bone marrow and its surrounding tissue: the bone. We hypothesized that bone marrow accessory cell populations might regulate the development of human bone precursor cells.

Peter G Eipers; Sujata Kale; Russell S Taichman; George G Pipia; Nancy A Swords; Kenneth G Mann; Michael W Long

2000-01-01

182

Precursors for the polymer-assisted deposition of films  

DOEpatents

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

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

2013-09-10

183

Stacked Optical Precursors from Amplitude and Phase Modulations  

SciTech Connect

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.

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

184

Precursor ion independent algorithm for top-down shotgun proteomics  

Microsoft Academic Search

We present a precursor ion independent top-down algorithm (PIITA) for use in automated assignment of protein identifications\\u000a from tandem mass spectra of whole proteins. To acquire the data, we utilize data-dependent acquisition to select protein precursor\\u000a ions eluting from a C4-based HPLC column for collision induced dissociation in the linear ion trap of an LTQ-Orbitrap mass\\u000a spectrometer. Gas-phase fractionation is

Yihsuan S. Tsai; Alexander Scherl; Jason L. Shaw; C. Logan MacKay; Scott A. Shaffer; Patrick R. R. Langridge-Smith; David R. Goodlett

2009-01-01

185

Improved Single-Source Precursors for Solar-Cell Absorbers  

NASA Technical Reports Server (NTRS)

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).

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

2007-01-01

186

Rb suppresses human cone-precursor-derived retinoblastoma tumours.  

PubMed

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

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

2014-10-16

187

Elements of the tsunami precursors' detection physics  

NASA Astrophysics Data System (ADS)

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.

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

188

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

PubMed

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

Quest, Dale W; Horsley, Joanne

2007-01-01

189

Plutonium Immobilization Project (PIP) Precursor Material Calcine Temperature  

SciTech Connect

As a result of the end of the Cold War, approximately 50 metric tons of plutonium are no longer needed and have been identified for disposition. A ceramic waste form is the chosen option for immobilization of the excess plutonium. The plutonium ceramic form then will be encased in high-level waste glass using can-in-canister technology for final disposition. The precursor materials are the non-radioactive components that are added to the plutonium feed stream to form the desired phases in the immobilization product. The precursor materials are blended and calcined prior to being mixed with the plutonium feed stream. The purpose of the calcine step is to remove any physical or chemical water retained in the precursors and convert any hydroxides or carbonates to the oxides. Initially, a temperature of 750 degrees C for a period of one hour was chosen for the calcining of the precursors. In this effort, several different calcine temperatures were investigated to evaluate the effect on initial phase formation (in the calcined precursors), thermal expansion of the pressed pellets during heating, and mineralogy and porosity of the final product.

Cozzi, A.D.

1999-07-29

190

Neural Precursor Differentiation Following Transplantation into Neocortex Is Dependent on Intrinsic Developmental State and Receptor Competence  

Microsoft Academic Search

Reconstruction of neocortical circuitry by transplantation of neural precursors, or by manipulation of endogenous precursors, may depend critically upon both local microenvironmental control signals and the intrinsic competence of populations of precursors to appropriately respond to external molecular controls. Dependence on the developmental state of donor or endogenous precursor cells in achieving appropriate differentiation, integration, and connectivity is not clearly

Volney L. Sheen; Matthew W. Arnold; Youzhen Wang; Jeffrey D. Macklis

1999-01-01

191

Testosterone precursors: use and abuse in pediatric athletes.  

PubMed

The dietary supplements androstenedione, dehydroepiandrosterone, and androstenediol are precursors in the endogenous production of testosterone. The efficacy and safety of these prohormones are not well established but are promoted to have the same androgenic effects on building muscle mass and strength as anabolic-androgenic steroids. Studies have demonstrated repeatedly that acute and long-term administration of these oral testosterone precursors does not effectively increase serum testosterone levels and fails to produce any significant changes in lean body mass, muscle strength, or performance improvement compared with placebo. The Anabolic Steroid Control Act of 2004 lists androstenedione as a schedule III controlled substance, and it is regulated by the U.S. Food and Drug Administration. Testosterone precursors are banned by most major sports organizations. PMID:17723877

Smurawa, Troy M; Congeni, Joseph A

2007-08-01

192

Production of multiple plant hormones from a single polyprotein precursor.  

PubMed

Some animal and yeast hormone genes produce prohormone polypeptides that are proteolytically processed to produce multiple copies of hormones with the same or different functions. In plants, four polypeptides have been identified that can be classed as hormones (intercellular chemical messengers) but none are known to be produced as multiple copies from a single precursor. Here we describe a polyprotein hormone precursor, present in tobacco plants, that gives rise to two polypeptide hormones, as often found in animals and yeast. The tobacco polypeptides activate the synthesis of defensive proteinase-inhibitor proteins in a manner similar to that of systemin, an 18-amino-acid polypeptide found in tomato plants. The two tobacco polypeptides are derived from each end of a 165-amino-acid precursor that bears no homology to tomato prosystemin. The data show that structurally diverse polypeptide hormones in different plant species can serve similar signalling roles, a condition not found in animals or yeast. PMID:11459063

Pearce, G; Moura, D S; Stratmann, J; Ryan, C A

2001-06-14

193

Solvothermal Molecular Precursor Routes to Semiconductor Film and Crystal Growth  

NASA Astrophysics Data System (ADS)

This research project explored the utility of molecular precursor decomposition in superheated non-aqueous solvents directed towards semiconductor crystal growth. Reactions were run in toluene, THF, and under solvent free conditions. An in situ precursor synthesis and decomposition resulted in GaN nanoparticles from simple starting materials (GaCl(3) and NaN(3)). Particle sizes range from about 10 to hundreds of nanometers. Upon annealing to 1000 degrees C, the poorly crystalline products ordered into crystalline hexagonal GaN and luminescence. The conversion of synthesized organometallic dimeric gallium amino precursors to GaN was less successful; however they showed some utility in vapor phase film growth. Silver and silver sulfide nanoparticles were also produced in a solvothermal system via silver azide decomposition producing particles in the 100 mn to micron size regime.

Gillan, Edward G.

2002-08-01

194

Waveform analysis of high-frequency PKP precursors  

NASA Astrophysics Data System (ADS)

The origin of precursors to PKP phases, which arrives typically 10-20~s before the direct arrivals, is still controversial. Are they produced by scattering on heterogeneities distributed in the whole mantle or in the base of the mantle? By calculating complete and exact 1st-order partial derivatives for PKP precursors with a new method up to 1~s-period (Fuji et al. 2012), we find that the sensitivity is significantly concentrated at the lowermost lower mantle around the PKP caustic. Around their onset time, sensitivity is concentrated around the ray path of PKPdf phase. We will present observations of PKP precursors from deep and shallow events recorded by dense regional broadband arrays and some preliminary results of waveform analysis.

Fuji, N.; Chevrot, S.

2012-12-01

195

Elastic precursor decay in S-200F beryllium  

NASA Astrophysics Data System (ADS)

We have performed a series of plate impact experiments on vacuum hot-pressed (VHP) S-200F Be at peak shock stresses between 2.1 and 23.0 GPa to gain insight into the dynamic strength (Hugoniot elastic limit (HEL)), equation-of-state, and damage behavior of this technologically important material. In this paper we focus on our VISAR observations of the evolution of elastic precursor amplitude with Be target thickness in a series of plate impact experiments conducted in both transmission and reverse geometry. We observe monotonic decay in precursor amplitude with run distance for sample thicknesses between 4 and 8 mm and present the HEL values obtained from these experiments. We will discuss the observed precursor decay with respect to the relative roles of twinning and dislocation-mediated slip in the overall dynamic material mechanical response.

Adams, C. D.; Anderson, W. W.; Blumenthal, W. R.; Gray, G. T., III

2014-05-01

196

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

197

The behaviors of optimal precursors during wintertime Eurasian blocking onset  

NASA Astrophysics Data System (ADS)

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

Jiang, Zhina; Wang, Donghai

2012-11-01

198

Posttranslational processing of concanavalin A precursors in jackbean cotyledons  

PubMed Central

Metabolic labeling of immature jackbean cotyledons with 14C-amino acids was used to determine the processing steps involved in the assembly of concanavalin A. Pulse-chase experiments and analyses of immunoprecipitated lectin forms indicated a complex series of events involving seven distinct species. The structural relatedness of all of the intermediate species was confirmed by two-dimensional mapping of 125I-tryptic peptides. An initial glycosylated precursor was deglycosylated and cleaved into smaller polypeptides, which subsequently reannealed over a period of 10-27 h. NH2-terminal sequencing of the abundant precursors confirmed that the intact subunit of concanavalin A was formed by the reannealing of two fragments, since the alignment of residues 1-118 and 119-237 was reversed in the final form of the lectin identified in the chase and the precursor first labeled. When the tissue was pulse-chased in the presence of monensin, processing of the glycosylated precursor was inhibited. The weak bases NH4Cl and chloroquine were without effect. Immunocytochemical studies showed that monensin treatment caused the accumulation of immunoreactive material at the cell surface and indicated that the ionophore had induced the secretion of a component normally destined for deposition within the protein bodies. Consideration of the tertiary structure of the glycosylated precursor and mature lectin showed that the entire series of processing events could occur without significant refolding of the initial translational product. Proteolytic events included removal of a peptide from the surface of the precursor molecule that connected the NH2- and COOH-termini of the mature protein. This processing activated the carbohydrate-binding activity of the lectin. The chase data suggest the occurrence of a simultaneous cleavage and formation of a peptide bond, raising the possibility that annealment of the fragments to give rise to the mature subunit involves a transpeptidation event rather than cleavage and subsequent religation. PMID:3958046

1986-01-01

199

Biosynthesis of the flavour precursors of onion and garlic.  

PubMed

Onion (Allium cepa), garlic (A. sativum) and other Alliums are important because of the culinary value of their flavours and odours. These are characteristic of each species and are created by chemical transformation of a series of volatile sulphur compounds generated by cleavage of relatively stable, odourless, S-alk(en)yl cysteine sulphoxide flavour precursors by the enzymes alliinase and lachrymatory-factor synthase. These secondary metabolites are S-methyl cysteine sulphoxide (MCSO, methiin; present in most Alliums, some Brassicaceae), S-allyl cysteine sulphoxide (ACSO, alliin; characteristic of garlic), S-trans-prop-1-enyl cysteine sulphoxide (PECSO, isoalliin; characteristic of onion), and S-propyl cysteine sulphoxide (PCSO, propiin; in onion and related species). Information from studies of the transformation of putative biosynthetic intermediates, radiolabelling, and from measurements of sulphur compounds within onion and garlic have provided information to suggest a biosynthetic pathway. This may involve alk(en)ylation of the cysteine in glutathione, followed by cleavage and oxidation to form the alk(en)yl cysteine sulphoxide flavour precursors. There is also evidence that synthesis of the flavour precursors may involve (thio)alk(en)ylation of cysteine or a precursor such as O-acetyl serine. Both routes may occur depending on the physiological state of the tissue. There are indications from the effects of environmental factors, such as the availability of sulphur, that control of the biosynthesis of each flavour precursor may be different. Cysteine and glutathione metabolism are discussed to indicate parallels with Allium flavour precursor biosynthesis. Finally, possible avenues for exploration to determine the origin in planta of the alk(en)yl groups are suggested. PMID:15234988

Jones, Meriel G; Hughes, Jill; Tregova, Angela; Milne, Jonothan; Tomsett, A Brian; Collin, Hamish A

2004-08-01

200

Molybdenum hexacarbonyl as a catalyst precursor for direct coal liquefaction  

SciTech Connect

Various transition metal carbonyls of the formula M{sub x}(CO){sub y} - where M is Cr, Fe, Co, Ni, Mo, Ru, Rh, W, Re - have been used effectively as catalyst precursors in laboratory-scale investigations of direct coal liquefaction. Most notable are the use of iron pentacarbonyl and molybdenum hexacarbonyl. In particular, Mo(CO){sub 6} in the presence of sulfur has been shown to be an excellent catalyst precursor for the liquefaction of coal and for promoting reactions with coal model compounds.

Warzinski, R.P.; Bockrath, B.C. [Pittsburgh Energy Technology Center, PA (United States)

1995-12-31

201

Binding of F-spondin to amyloid- precursor protein: A candidate amyloid- precursor protein ligand that modulates amyloid- precursor protein cleavage  

Microsoft Academic Search

Amyloid- precursor protein (APP), a type I membrane protein, is physiologically processed by - or -secretases that cleave APP N-terminal to the transmembrane region. Extracellular -\\/-cleavage of APP generates a large secreted N-terminal fragment, and a smaller cellular C-terminal fragment. Subsequent -secretase cleavage in the transmembrane region of the C-terminal fragment induces secretion of small extracellular peptides, including A40 and

Angela Ho; Thomas C. Südhof

2004-01-01

202

Environment Conscious, Biomorphic Ceramics from Pine and Jelutong Wood Precursors  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

203

Amyloid Precursor Protein Is Trafficked and Secreted via Synaptic Vesicles  

Microsoft Academic Search

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

Teja W. Groemer; Cora S. Thiel; Matthew Holt; Dietmar Riedel; Yunfeng Hua; Jana Hüve; Benjamin G. Wilhelm; Jürgen Klingauf; Hitoshi Okazawa

2011-01-01

204

The role of catalyst precursor anions in coal gasification  

Microsoft Academic Search

The aims of the proposed project are to enrich our understanding of the roles of various aqueous soluble catalyst precursor anions on the surface electrical properties of coal and to ascertain the influence of the surface charge on the adsorption, dispersion, and activities of calcium and potassium. These goals will be achieved by impregnating a demineralized North Dakota lignite (PSOC

Abotsi; G. M. K

1992-01-01

205

Earthquake nucleation process as a precursor of a mainshock  

E-print Network

Earthquake nucleation process is studied as a precursor of a mainshock both analytically and numerically on the basis of the one-dimensional Burridge-Knopoff model obeying the rate- and state-dependent friction law. The properties of the nucleation dynamics, the nucleation lengths and the duration times are clarified together with their continuum limits.

Ueda, Yushi; Kakui, Shingo; Yamamoto, Takumi; Kawamura, Hikaru

2014-01-01

206

Precursor Lesions of Pancreatic Cancer: Molecular Pathology and Clinical Implications  

Microsoft Academic Search

Background: Pancreatic cancer is a lethal disease, with near uniform 5-year mortality rates. The key to improving survival of pancreatic cancer rests upon early detection of this neoplasm at a resectable, and hence potentially curable, stage. Methods: We review the current state of the literature vis-à-vis the three common precursor lesions of pancreatic adenocarcinoma: pancreatic intraepithelial neoplasia, intraductal papillary mucinous

Mansher Singh; Anirban Maitra

2007-01-01

207

Effect of molybdenum disulfide precursor on catalyst activity  

SciTech Connect

Molybdenum disulfide is a well recognized coal liquefaction catalyst. Recently, work has concentrated on unsupported forms of the catalyst commonly referred to as dispersed catalysts. The active form of the catalyst is believed to have a stoichiometry at or near MoS{sub 2} regardless of the precursor. The higher activities found for some precursors are usually attributed to a higher degree of dispersion. The authors have examined the chemistry promoted by two MoS{sub 2} precursors. (NH{sub 4}){sub 2}MoS{sub 4} decomposes under typical liquefaction conditions to give an active MoS{sub 2} catalyst presumably via a MoS{sub 3} intermediate. MoS{sub 3} can be prepared in a separate step by the acidification of an aqueous solution of (NH{sub 4}){sub 2}MoS{sub 4}. The abilities of these two MoS{sub 2} precursors to promote hydrogenation and cationic reactions were compared using dimethylnaphthalene and ethylnaphthalene as probes. The extent of hydrogenation and isomerization of the probes were remarkably different even though the X-ray diffraction of the recovered catalysts were essentially identical and were consistent with 30A{degree} diameter MoS{sub 2} particles.

Schroeder, K.T.; Bockrath, B.C.; Davis, H.; Miller, R.D. (Pittsburgh Energy Technology Center, PA (United States))

1990-08-01

208

Particulate and THM precursor removal with ferric chloride  

SciTech Connect

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.

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

1999-11-01

209

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...

210

The precursor to an industrial software metrics program  

Microsoft Academic Search

A common reason for why software metric programs dasiafailpsila is through lack of participant support and commitment. In this paper, we describe the results of a study which examined the knowledge that subjects had and the opinions they had formed of previous metrics initiatives in the same organization. The research was undertaken by one of the authors as a precursor

S. T. Parkinson; S. Counsell; M. Norman; R. M. Hierons; M. Lycett

2008-01-01

211

The Precursor to an Industrial Software Metrics Program  

Microsoft Academic Search

A common reason for why software metric programs 'fail' is through lack of participant support and commitment. In this paper, we describe the results of a study which examined the knowledge that subjects had and the opinions they had formed of previous metrics initiatives in the same organization. The research was undertaken by one of the authors as a precursor

S. T. Parkinson; S. Counsell; M. Norman; R. M. Hierons; M. Lycett

2009-01-01

212

The oligodendrocyte precursor cell in health and disease  

Microsoft Academic Search

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

Joel M Levine; Richard Reynolds; James W Fawcett

2001-01-01

213

Introduction In many vertebrate cell lineages, precursor cells divide a  

E-print Network

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

Richardson, William D.

214

Precursor-directed biosynthesis of curcumin analogs in Escherichia coli.  

PubMed

Curcuminoids, natural products in the rhizome of turmeric, show various biological activities, including antioxidant and antitumor activities. For this reason, curcuminoids have been focused on as potential pharmaceuticals. Exogenous supplementation with various carboxylate precursors in genetically engineered Escherichia coli cells carrying an artificially assembled pathway for curcuminoid biosynthesis led to the production of 17 unnatural curcuminoids. PMID:20208337

Katsuyama, Yohei; Hirose, Yutaka; Funa, Nobutaka; Ohnishi, Yasuo; Horinouchi, Sueharu

2010-01-01

215

PILOT SCALE EVALUATION OF PHOTOLYTIC OZONATION FOR TRIHALOMETHANE PRECURSOR REMOVAL  

EPA Science Inventory

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

216

Modelling precursor decay in AD-99.5 Alumina  

NASA Astrophysics Data System (ADS)

In this paper we present a simple model to explain the absence of precursor decay in the Coor's AD-99 5 Alumina ceramic, as shown by Grady in his plate impact experiments. The model is incorporated into the Research EPIC 95 finite element code. The simulations compare well with Grady's results.

Simha, C. Hari Manoj; Bless, S. J.; Bedford, A.

1998-07-01

217

Modelling Precursor Decay in AD-99.5 Alumnina  

NASA Astrophysics Data System (ADS)

In this paper we present a simple model to explain the absence of precursor decay in the Coor's AD-99.5 Alumina ceramic, as shown by Grady in his plate impact experiments. The model is incorporated in the WONDY finite difference code. The simulations of Grady's experiments compare well with the results.

Manoj Simha, C. Hari; Bless, Stephan J.; Bedford, Anthony M.

1997-07-01

218

RIVERBANK FILTRATION: FATE OF DBP PRECURSORS AND SELECTED MICROORGANISMS  

EPA Science Inventory

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

219

N-linked glycosylation selectively regulates autonomous precursor BCR function  

Microsoft Academic Search

Developing B cells express distinct classes of B cell antigen receptors (BCRs) that differ in their heavy chain (HC). Although only ?HC is expressed in early stages, ?HC-containing BCRs dominate on the surface of mature B cells. The reason for the tightly regulated expression of these receptors is poorly understood. Here we show that ?HC was specifically required for precursor

Rudolf Übelhart; Martina P Bach; Cathrin Eschbach; Thomas Wossning; Michael Reth; Hassan Jumaa

2010-01-01

220

Inflammatory arthritis increases mouse osteoclast precursors with myeloid suppressor function  

PubMed Central

Increased osteoclastic bone resorption leads to periarticular erosions and systemic osteoporosis in RA patients. Although a great deal is known about how osteoclasts differentiate from precursors and resorb bone, the identity of an osteoclast precursor (OCP) population in vivo and its regulatory role in RA remains elusive. Here, we report the identification of a CD11b–/loLy6Chi BM population with OCP activity in vitro and in vivo. These cells, which can be distinguished from previously characterized precursors in the myeloid lineage, display features of both M1 and M2 monocytes and expand in inflammatory arthritis models. Surprisingly, in one mouse model of RA (adoptive transfer of SKG arthritis), cotransfer of OCP with SKG CD4+ T cells diminished inflammatory arthritis. Similar to monocytic myeloid-derived suppressor cells (M-MDSCs), OCPs suppressed CD4+ and CD8+ T cell proliferation in vitro through the production of NO. This study identifies a BM myeloid precursor population with osteoclastic and T cell–suppressive activity that is expanded in inflammatory arthritis. Therapeutic strategies that prevent the development of OCPs into mature bone-resorbing cells could simultaneously prevent bone resorption and generate an antiinflammatory milieu in the RA joint. PMID:23114597

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

2012-01-01

221

TRIHALOMETHANE PRECURSOR REMOVAL BY THE MAGNESIUM CARBONATE PROCESS  

EPA Science Inventory

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

222

College Student Stress: A Predictor of Eating Disorder Precursor Behaviors  

ERIC Educational Resources Information Center

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

Shelton, Virginia L.; Valkyrie, Karena T.

2010-01-01

223

Measurement of excitation energy of neutron-rich precursor fragments  

NASA Astrophysics Data System (ADS)

Projectile fragmentation forms the basis for beam production at radioactive beam facilities such as the National Superconducting Cyclotron Laboratory (NSCL), yet uncertainties remain about the specifics of the production mechanism. For example, very little is known about the excitation energy of the precursors of the observed final fragments. In the present work, isotopes of sodium, neon, and fluorine produced in the fragmentation of a 32 Mg beam at 86 MeV/nucleon in a beryllium target, ranging in mass loss from DeltaA = 3--12, were observed and the coincident neutrons were detected using the Modular Neutron Array (MoNA). Neutron hit multiplicity in MoNA was compared to output from the statistical evaporation model PACE which was passed through a GEANT4 simulation to account for detector response with a X2v analysis. The neutron hit multiplicity distributions were used to determine the mass loss and excitation energy of the precursor fragments created in the fast step of the reaction. The mass loss and excitation energy were compared to abrasion/ablation models and an internuclear cascade model, ISABEL. For sodium and neon observed fragments, a single precursor mass was found, with a wide range of high excitation energies, up to 60 MeV. Observed fluorine isotopes were also found to have high excitation energies, ranging from 40--80 MeV, but with some variation in precursor mass.

Mosby, Michelle Anthea

224

Process for producing ceramic nitrides anc carbonitrides and their precursors  

DOEpatents

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.

Brown, G.M.; Maya, L.

1987-02-25

225

Climate response to regional emissions of tropospheric ozone precursors  

Microsoft Academic Search

Climate change mitigation measures are likely to affect the distribution of emissions of ozone precursors. While the gases regulated in the Kyoto Protocol are long-lived and thus independent of the location of the emissions, the climate impact of emissions of NOx through ozone production is very variable due to non-linear chemical effects. At high ambient NOx concentrations additional NOx emissions

T. K. Berntsen; J. S. Fuglestvedt; D. Hauglustaine; M. Joshi; K. P. Shine; L. Li; M. Ponater; N. Stuber; R. Sausen

2003-01-01

226

Barium strontium titanate powder obtained by polymeric precursor method  

SciTech Connect

Pure barium strontium titanate powder, with Ba/Sr ratio of 80/20 was prepared by the polymeric precursor method (also called Pechini process). The powder was obtained after a calcination at 800 deg. C for 8 h and characterized by XRD, IR, BET and SEM. The requirements to avoid barium carbonate as a secondary phase are presented and discussed in detail.

Ries, A.; Simoes, A.Z.; Cilense, M.; Zaghete, M.A.; Varela, J.A

2003-03-15

227

Prenatal diagnosis of succinic semialdehyde dehydrogenase deficiency: increased accuracy employing DNA, enzyme, and metabolite analyses.  

PubMed

Inherited succinic semialdehyde dehydrogenase (SSADH; EC1.2.1.24; McKusick 271980) deficiency is a defect of GABA degradation which leads to accumulation of 4-hydroxybutyric acid (gamma-hydroxybutyric acid; GHB) in physiologic fluids of patients. Prenatal diagnosis (PND) was performed in three at-risk pregnancies employing combinations of: (1) reverse-transcription-polymerase chain reaction (RT-PCR) and genomic DNA amplification followed by sequencing using isolated leukocytes or cultured human lymphoblasts; (2) GHB quantitation in amniotic fluid; or (3) SSADH enzyme assay in chorionic villus (CV) and/or amniocytes. In two pregnancies, all analyses were concordant for prediction of disease status in the fetus. In the third case, enzyme activity in CV (deficient) and metabolite analysis in amniotic fluid (normal) were discordant. For clarification, mutation analysis was undertaken in CV, confirming heterozygosity for the mutation previously identified in the proband. We hypothesize that delayed transit time for shipment of CV between Greece and the United States (8 days) led to enhanced degradation of heterozygous SSADH enzyme activity. Our data demonstrate the importance of combined metabolite, enzyme, and DNA analysis for increased accuracy in the PND of SSADH deficiency. PMID:11243727

Hogema, B M; Akaboshi, S; Taylor, M; Salomons, G S; Jakobs, C; Schutgens, R B; Wilcken, B; Worthington, S; Maropoulos, G; Grompe, M; Gibson, K M

2001-03-01

228

Medications acting on the GABA system in the treatment of alcoholic patients.  

PubMed

Gamma aminobutyric acid (GABA) represents the major inhibitory neurotransmitter of the central nervous system. Ethanol as well as benzodiazepines (BDZs) and some anticonvulsant drugs directly affect GABAA receptors inducing similar anxiolytic, sedativehypnotic, and anticonvulsant effects. Since BDZs have proven their efficacy in ameliorating symptoms and in decreasing the risk of seizures and delirium tremens, they are the drugs of choice for the treatment of alcohol withdrawal syndrome (AWS). However, due to their addictive potential and lack of safety when combined with alcohol, BDZs are usually not recommended for the maintenance of alcohol abstinence. Other GABA-ergic medications represent potentially promising drugs useful in the treatment of AWS and in maintaining alcohol abstinence. Indeed, available studies have demonstrated that clomethiazole, gabapentin and gamma hydroxybutyrate (GHB) present a similar efficacy to BDZs in suppressing AWS. In addition, current evidence also indicates that gabapentin and GHB do not have significant interactions with ethanol that render them safe to use in maintaining alcohol abstinence. Moreover, gabapentin and valproic acid may be beneficial in maintaining alcohol abstinence in alcoholics with psychiatric co-morbidity. Pregabalin, neurosteroids, tiagabine, and vigabatrin need further clinical evidence of efficacy, safety and tolerability. Thus, given the importance of GABA-ergic mechanisms in the development and maintenance of alcohol dependence, and the very interesting results currently achieved, more research on GABAergic agents is warranted. PMID:20482512

Caputo, Fabio; Bernardi, Mauro

2010-01-01

229

Solution precursor plasma deposition of nanostructured ZnO coatings  

SciTech Connect

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

Tummala, Raghavender [Department of Mechanical Engineering, University of Michigan - Dearborn, MI 48128 (United States)] [Department of Mechanical Engineering, University of Michigan - Dearborn, MI 48128 (United States); Guduru, Ramesh K., E-mail: rkguduru@umich.edu [Department of Mechanical Engineering, University of Michigan - Dearborn, MI 48128 (United States); Mohanty, Pravansu S. [Department of Mechanical Engineering, University of Michigan - Dearborn, MI 48128 (United States)] [Department of Mechanical Engineering, University of Michigan - Dearborn, MI 48128 (United States)

2011-08-15

230

Making Single-Source Precursors of Ternary Semiconductors  

NASA Technical Reports Server (NTRS)

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.

Hepp, Aloysius; Banger, Kulbindre K.

2007-01-01

231

Precursors to the shear failure of rock discontinuities  

NASA Astrophysics Data System (ADS)

geophysical monitoring of potential failure along mechanical discontinuities in rock requires identification of precursory signatures to failure in geophysical signals. Active ultrasonic monitoring of shear failure along frictional discontinuities was performed to determine the signatures of potential failure. An instrumented direct shear apparatus was used to apply a constant shearing rate to a discontinuity that was held under a constant normal stress. Transmitted and reflected compressional and shear waves were recorded during the shearing process. Ultrasonic precursors were identified as distinct maxima in the amplitude of transmitted shear waves as well as minima in the amplitude of reflected shear waves that occurred well before the peak shear strength of a frictional discontinuity. The precursors are linked to changes in the local shear specific stiffness along the discontinuity, while the discontinuity's macroscopic shear strength continues to increase prior to failure.

Hedayat, Ahmadreza; Pyrak-Nolte, Laura J.; Bobet, Antonio

2014-08-01

232

Glycerol, an underestimated flavor precursor in the Maillard reaction.  

PubMed

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

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

2013-10-30

233

Ceramic fibers from Si-B-C polymer precursors  

NASA Technical Reports Server (NTRS)

Non-oxide ceramics such as silicon carbide (SiC), silicon nitride (Si3N4), and silicon borides (SiB4, SiB6) have thermal stability, oxidation resistance, hardness, and varied electrical properties. All these materials can be prepared in a fiber form from a suitable polymer precursor. The above mentioned fibers, when tested over a temperature range from 25 to 1400 C, experience degradation at elevated temperatures. Past work in ceramic materials has shown that the strength of ceramics containing both carbides and borides is sustained at elevated temperatures, with minimum oxidation. The work presented here describes the formation of ceramic fibers containing both elements, boron and silicon, prepared via the polymer precursor route previously reported by the authors, and discusses the fiber mechanical properties that are retained over the temperature range studied.

Riccitiello, S. R.; Hsu, M. S.; Chen, T. S.

1993-01-01

234

Magnetic property of the precursor of polyacenic semiconductive material  

NASA Astrophysics Data System (ADS)

In association with the studies of recent organic ``ferromagnets,'' measurements of magnetic properties including the magnetization, the magnetic susceptibility, and the electron spin resonance of the precursor of the polyacenic semiconductive material prepared from pyrolytic treatment of phenol-formaldehyde resin at a low temperature (220°C) have been carried out. The overall results have suggested that, in the skeleton of this precursor, there are structurally some parts containing the parallel-spin alignments with the averaged spin multiplicity S of unity or even higher in addition to a small amount of general isolated spins with S=1/2. Triphenylmethyl radicals possibly appearing in the skeleton have been deduced to be responsible for the origin of such peculiar spin alignments.

Kobashi, Masahiro; Sanekata, Hideki; Tanaka, Kazuyoshi; Yamabe, Tokio; Yamauchi, Jun; Yata, Shizukuni

1991-07-01

235

Can precursors improve the transmission of energy at optical frequencies?  

PubMed Central

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

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

2009-01-01

236

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

NASA Astrophysics Data System (ADS)

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 payload it is possible to monitor all main parameters of seismoionospheric precursors. The active methods and airglow imager are used for detection of anomalous plasma structure during a few days before first shock. Supported in part by Tesla Labs, Inc., La Jolla, CA 92038-2946. ^1Also with Tesla Labs, Inc., La Jolla, CA 92038-2946. ^2V. Stefan (Editor-in-Chief). Environmental Physics. Frontiers in Interdisciplinary Physics series of the La Jolla International School of Physics, The Institute for Advanced Physics Studies, La Jolla, CA (IAPS Press, La Jolla, 1996).

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

1996-11-01

237

Structure of the murine leukemia virus envelope glycoprotein precursor.  

PubMed Central

The glycosylated env gene precurosr (Pr80env) of Moloney murine leukemia virus has been isolated by selective immunoprecipitation. Use of the drug tunicamycin to inhibit nascent glycosylation or specific cleavage with endoglycosidase H demonstrated that the precursor contained an apoprotein with a molecular weight of 60,000. The finished virion glycoprotein (gp70) was largely resistant to the action of endoglycosidase H. Chromatography of the glycopeptides of Pr80env in conjunction with endoglycosidase H digestion studies suggested that the precursor contained two distinct major glycosylation sites. Analysis of partial proteolytic cleavage fragments of Pr80env before and after endoglycosidase H treatment placed the two glycosylation sites within a 30,000-dalton region of the apoprotein sequence. Kinetic experiments showed that carbohydrate processing as well as proteolytic cleavage are late steps in the maturation of Pr80env. Images PMID:430608

Witte, O N; Wirth, D F

1979-01-01

238

Fission-Based Electric Propulsion for Interstellar Precursor Missions  

SciTech Connect

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.

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

1999-11-03

239

Low-temperature nitridation of Fe nanoparticles precursor.  

PubMed

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

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

2009-12-01

240

Intraspinal transplantation of mouse and human neural precursor cells  

PubMed Central

This unit describes the preparation and transplantation of human neural precursor cells (hNPCs) and mouse neural precursor cells (mNPCs) into the thoracic region of the mouse spinal cord. The techniques in this unit also describe how to prepare the mouse for surgery by performing a laminectomy to expose the spinal cord for transplantation. Here we show NPCs genetically labeled with eGFP transplanted into the spinal cord of a mouse following viralmediated demyelination can efficiently be detected via eGFP expression. Transplantation of these cells into the spinal cord is an efficacious way to determine their effects in neurological disorders such as multiple sclerosis, Alzheimer's disease, and spinal cord injury. PMID:24510791

Weinger, Jason G.; Chen, Lu; Coleman, Ronald; Leang, Ronika; Plaisted, Warren C.; Loring, Jeanne F.; Lane, Thomas E.

2013-01-01

241

An active precursor in assembly of yeast nuclear ribonuclease P.  

PubMed Central

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

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

2002-01-01

242

40 CFR 141.135 - Treatment technique for control of disinfection byproduct (DBP) precursors.  

Code of Federal Regulations, 2013 CFR

...disinfection byproduct (DBP) precursors. 141.135 Section 141.135 Protection of Environment ENVIRONMENTAL...PRIMARY DRINKING WATER REGULATIONS Disinfectant Residuals...Disinfection Byproduct Precursors § 141.135 Treatment technique for control of disinfection...

2013-07-01

243

40 CFR 141.135 - Treatment technique for control of disinfection byproduct (DBP) precursors.  

Code of Federal Regulations, 2011 CFR

...disinfection byproduct (DBP) precursors. 141.135 Section 141.135 Protection of Environment ENVIRONMENTAL...PRIMARY DRINKING WATER REGULATIONS Disinfectant Residuals...Disinfection Byproduct Precursors § 141.135 Treatment technique for control of disinfection...

2011-07-01

244

40 CFR 141.135 - Treatment technique for control of disinfection byproduct (DBP) precursors.  

Code of Federal Regulations, 2010 CFR

...disinfection byproduct (DBP) precursors. 141.135 Section 141.135 Protection of Environment ENVIRONMENTAL...PRIMARY DRINKING WATER REGULATIONS Disinfectant Residuals...Disinfection Byproduct Precursors § 141.135 Treatment technique for control of disinfection...

2010-07-01

245

40 CFR 141.135 - Treatment technique for control of disinfection byproduct (DBP) precursors.  

Code of Federal Regulations, 2012 CFR

...disinfection byproduct (DBP) precursors. 141.135 Section 141.135 Protection of Environment ENVIRONMENTAL...PRIMARY DRINKING WATER REGULATIONS Disinfectant Residuals...Disinfection Byproduct Precursors § 141.135 Treatment technique for control of disinfection...

2012-07-01

246

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

NASA Technical Reports Server (NTRS)

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.

Groen, Frank

2010-01-01

247

MHD precursor to disruption in Iran tokamak 1  

E-print Network

The purpose of this paper is to further investigate the major disruptions occurring in low-q(a) discharges in Iran Tokamak 1, and to compare the theoretical and experimental results for the rate of island growth. The study of precursor phase of disruption can be predicted and avoided using suitable control systems. In this paper are described the stability analysis and the observed growth rates indicate that the rotating modes are tearing modes.

Hojabri, A; Hajakbari, F; Hojabri, Alireza; Ghoranneviss, Mahmmod; Hajakbari, Fatemeh

2004-01-01

248

Synthesis of S-doped graphene by liquid precursor  

Microsoft Academic Search

Doping is a common and effective approach to tailor semiconductor properties. Here, we demonstrate the growth of large-area sulfur (S)-doped graphene sheets on copper substrate via the chemical vapor deposition technique by using liquid organics (hexane in the presence of S) as the precursor. We found that S could be doped into graphene’s lattice and mainly formed linear nanodomains, which

Hui Gao; Zheng Liu; Li Song; Wenhua Guo; Wei Gao; Lijie Ci; Amrita Rao; Weijin Quan; Robert Vajtai; Pulickel M Ajayan

2012-01-01

249

Sirt1 increases skeletal muscle precursor cell proliferation  

Microsoft Academic Search

It is important to understand the mechanisms that control muscle precursor cell (MPC) proliferation for the development of countermeasures to offset the deleterious effects of the aging-related loss of skeletal muscle mass (and myonuclei) and the impaired ability of old muscle to regrow and regenerate. Over-expression of the NAD+-dependent histone deacetylase Sirt1 increased MPC proliferation and cell cycle progression as

Christopher R. Rathbone; Frank W. Booth; Simon J. Lees

2009-01-01

250

Highly exfoliated graphite as a precursor for graphene materials  

Microsoft Academic Search

In this paper an alternative precursor for exfoliated graphite-C2F*R used to produce a highly exfoliated graphitic material which is a multilayered graphene containing on average 10-15 layers is studied. This material is further exfoliated and functionalized with oxygen groups by acid treatment to yield very stable surfactant-free colloidal dispersions of chemically modified graphene nanosheets in water or alcohol medium.

E. D. Grayfer; A. S. Nazarov; V. G. Makotchenko; Sung-Jin Kim; V. E. Fedorov

2010-01-01

251

Epidermal sphingomyelins are precursors for selected stratum corneum ceramides  

Microsoft Academic Search

Epidermal ceramides (Cer) comprise a heteroge- neous family of seven species, including two unique v -hydroxylated Cer, that are key components of the stratum corneum (SC) intercellular lamellar membranes responsi- ble for the epidermal permeability barrier. Although both glucosylceramide (GlcCer) and the phospho-sphingolipid sphingomyelin (SM) are potential precursors of SC Cer, based on reported chemical structures of epidermal GlcCer and

Yoshikazu Uchida; Mariko Hara; Hiroyuki Nishio; Ellen Sidransky; Shintaro Inoue; Fujio Otsuka; Akemi Suzuki; Peter M. Elias; Walter M. Holleran; Sumiko Hamanaka

252

Single-walled hollow nanospheres assembled from the aluminogermanate precursors.  

PubMed

Ordered single-walled hollow aluminogermanate (ALGE) nanospheres (NSs) with average monodisperse diameters of 5 nm have been synthesized for the first time using simple pH control. This involved basification of the ALGE precursors (having an Al/Ge ratio of 1.33) to a pH value of 13, followed by immediate acidification to a pH value of 9. PMID:19774254

Bac, Bui Hoang; Song, Yungoo; Kim, Myung Hun; Lee, Young-Boo; Kang, Il Mo

2009-10-14

253

The Crab Nebula's Composition and Precursor Star Mass  

E-print Network

We present results of new photoionization calculations for investigating gaseous regions that represent potentially expected stages of nuclear processing in the Crab Nebula supernova remnant. In addition to gas resulting from CNO-processing and oxygen-burning, as previously reported, a large component of the nebula appears to be carbon-rich. These results suggest that the precursor star had an initial mass of 9.5 solar masses or more.

Gordon M. MacAlpine; Timothy J. Satterfield

2008-06-08

254

Key precursor data in aggregate delayed-neutron calculations  

Microsoft Academic Search

The reactivity calculations with the delayed neutron (DN) six-group parameter sets in ENDF\\/B-VI were reported to give significant underestimates for long period (tens of seconds). The parameter sets were obtained form the summation calculations with ENDF\\/B-VI fission yields and decay data files. In this paper, we try to identify the precursor data that cause the significant underestimates. Because of the

T. Sanami; K. Oyamatsu; Y. Kukita

255

Optical Precursors in Rubidium Vapor and Their Relation to Superradiance  

E-print Network

of Committee, Alexei V. Sokolov Committee Members, Philip R. Hemmer George R. Welch Head of Department, Edward Fry August 2011 Major Subject: Physics iii ABSTRACT Optical Precursors in Rubidium Vapor and Their Relation to Superradiance... guidance and support throughout the course of this research. I would like to thank my committee member, Dr. Hemmer, for his teaching of many experiment skills in the beginning of my research. I would like to thank my committee member, Dr. Welch...

Yang, Wenlong

2012-10-19

256

Molecular Role of Zinc in Neuronal Precursor Proliferation and Survival  

Microsoft Academic Search

Although zinc has been implicated in the functionality of the hippocampus since the 1970’s, the recent discovery of adult neuronal stem cells in this region of the brain provides the potential for novel zinc-regulated hippocampal processes. The current work addressed the role of zinc in the proliferation, maintenance, and survival of neuronal precursor cells. First, this work employed a genome-wide

Rikki S Corniola

2010-01-01

257

Hydroxycinnamic acid ethyl esters as precursors to ethylphenols in wine.  

PubMed

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

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

2012-03-01

258

Efficient synthesis of multifunctional furanoid C-glycoamino acid precursors  

Microsoft Academic Search

Ready access to constrained, multifunctionalized, hydrolytically stable amino acids has been established by the synthesis of their direct precursors using 2,5-anhydro-3-azido-3-deoxy-d-altrose (a ‘formyl azido-C-glycofuranoside’), or its readily available, stable synthetic equivalent [(1R) and (1S)-2,5-anhydro-3-azido-4,6-O-benzylidene-3-deoxy-1-fluoro-1-O-methyl-d-altritol], as novel molecular scaffolds.

Yolanda Vera-Ayoso; Pastora Borrachero; Francisca Cabrera-Escribano; Manuel Gómez-Guillén

2005-01-01

259

Chromophore-bearing zeolite materials as precursors of colored ceramics  

Microsoft Academic Search

This work investigates the possibility to obtain colored ceramics by firing compacts of the synthetic zeolite A, pre-loaded with chromophore metal cations, and gives also a preliminary evaluation of their technical properties. Natural zeolite-bearing materials, i.e., clinoptilolite- and phillipsite-rich tuffs, which naturally contain chromofore agents, such as iron oxides and hydroxides, have also been considered as ceramic precursors. The results

B. Liguori; A. Cassese; C. Colella

2005-01-01

260

Cell-density-dependent regulation of neural precursor cell function  

Microsoft Academic Search

Stress-induced reductions of neural precursor cells from the subgranular zone of the hippocampal dentate gyrus have been linked to impaired neurogenesis and cognitive dysfunction. Given the importance of redox state in regulating multiple damage-responsive pathways in the CNS, we hypothesize that oxidative stress plays a major role in affecting neurogenesis and subsequent cognitive function after cell injury\\/depletion. Using an in

Charles L. Limoli; Radoslaw Rola; Erich Giedzinski; Sailaja Mantha; Ting-Ting Huang; John R. Fike

2004-01-01

261

Modulation of amyloid precursor protein processing by synthetic ceramide analogues  

Microsoft Academic Search

Previous studies suggest that membrane lipids may regulate proteolytic processing of the amyloid precursor protein (APP) to generate amyloid-beta peptide (Abeta). In the present study, we have assessed the capacity for a series of structurally related synthetic ceramide analogues to modulate APP processing in vitro. The compounds tested are established glucosylceramide synthase (GS) inhibitors based on the d-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP) structure.

Hongyun Li; Woojin S. Kim; Gilles J. Guillemin; Andrew F. Hill; Genevieve Evin; Brett Garner

2010-01-01

262

Accident sequence precursor events with age-related contributors  

SciTech Connect

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

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

1995-12-31

263

The identification of a phospholipase B precursor in human neutrophils.  

PubMed

A phospholipase B (PLB) precursor was purified from normal human granulocytes using Sephadex G-75, Mono-S cation-exchange and hydroxyapatite columns. The molecular mass of the protein was estimated to be approximately 130 kDa by gel filtration and 22 and 42 kDa by SDS/PAGE. Tryptic peptide and sequence analyses by MALDI-TOF and tandem mass spectrometry (MS/MS) identified the protein as a FLJ22662 (Homo sapiens) gene product, a homologue of the amoeba Dictyostelium discoideum PLB. The native protein needed modifications to acquire deacylation activity against phospholipids including phosphatidylcholine, phosphatidylinositol, phosphatidylethanolamine and lysophospholipids. Enzyme activity was associated with fragments derived from the 42 kDa fragment. The enzyme revealed a PLB nature by removing fatty acids from both the sn-1 and sn-2 positions of phospholipids. The enzyme is active at a broad pH range with an optimum of 7.4. Immunoblotting of neutrophil postnuclear supernatant using antibodies against the 42 kDa fragment detected a band at a molecular mass of 42 kDa, indicating a neutrophil origin of the novel PLB precursor. The existence of the PLB precursor in neutrophils and its enzymatic activity against phospholipids suggest a role in the defence against invading microorganisms and in the generation of lipid mediators of inflammation. PMID:19019078

Xu, Shengyuan; Zhao, Linshu; Larsson, Anders; Venge, Per

2009-01-01

264

LWIR hyperspectral imaging application and detection of chemical precursors  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

265

Phylogenetic appearance of Neuropeptide S precursor proteins in tetrapods  

PubMed Central

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

Reinscheid, Rainer K.

2007-01-01

266

Precursors of primary nucleation induced by flow in isotactic polypropylene  

NASA Astrophysics Data System (ADS)

Small-angle X-ray scattering (SAXS) patterns of the sheared isotactic polypropylene (i-PP) melt at 175°C, above the nominal melting point of 162°C, showed development of oriented structures or aggregates of polymer molecules that did not disappear even after a long time relaxation (up to 2 h). However, the corresponding wide-angle X-ray diffraction (WAXD) patterns did not show any visible Bragg reflections, suggesting that the induced structures are probably non-crystalline. The results suggest that metastable aggregates of polymer molecules are generated in the melt by assembly of bundle of oriented chain segments (especially in long chains). We speculate that the oriented aggregates of chain segments are precursors of primary nuclei. The spatial arrangement of these precursors showed a layer-like superstructure, evident by the appearance of the meridional maxima in SAXS. The spacing between the ‘layers’ was estimated to be 430 Å. A microstructural model of the orientation-induced precursors for primary nucleation is presented. An Avrami model was used to fit the evolution of the oriented structures in i-PP melt, which provided insights into the early stages of polymer crystallization.

Somani, Rajesh H.; Yang, Ling; Hsiao, Benjamin S.

2002-02-01

267

Observations of Electromagnetic Whistler Precursors at Supercritical Interplanetary Shocks  

NASA Technical Reports Server (NTRS)

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.

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

268

Reduction of precursor decay anomaly in single crystal lithium fluoride  

NASA Astrophysics Data System (ADS)

The purpose of this study is to reveal that the precursor decay anomaly in single crystal lithium fluoride is reduced by Sano's decay curve [Y. Sano, J. Appl. Phys. 85, 7616 (1999)], which is much smaller in slope than Asay's decay curve [J. R. Asay, G. R. Fowles, G. E. Duvall, M. H. Miles, and R. F. Tinder, J. Appl. Phys. 43, 2132 (1972)]. To this end, strain, particle, velocity, and stress in a precursor and near the leading edge of the follower changing with time along Sano's decay curve are first analyzed quantitatively. The analysis verified the existence of degenerate contraction waves I and II and a subrarefaction wave R', and the decay process [Y. Sano, J. Appl. Phys. 77, 3746 (1995)] caused in sequence by evolving followers C, I, II, R', Rb. Next, inequalities relating decay rates qualitatively to plastic strain rates at the leading edge of the follower, which are derived using the properties of the followers, are incorporated into the analysis. Calculation results showed that the plastic strain rates were reduced by low decay rates. This indicates that the precursor decay anomaly might be greatly reduced by Sano's decay curve.

Sano, Yukio

2000-08-01

269

Lineage specification of neuronal precursors in the mouse spinal cord.  

PubMed Central

We have investigated the differentiation potential of precursor cells within the developing spinal cord of mice and have shown that spinal cord cells from embryonic day 10 specifically give rise to neurons when plated onto an astrocytic monolayer, Ast-1. These neurons had the morphology of motor neurons and > 83% expressed the motor neuron markers choline acetyltransferase, peripherin, calcitonin gene-related peptide, and L-14. By comparison, < 10% of the neurons arising on monolayers of other neural cell lines or 3T3 fibroblasts had motor neuron characteristics. Cells derived from dorsal, intermediate, and ventral regions of the spinal cord all behaved similarly and gave rise to motor neuron-like cells when plated onto Ast-1. By using cells that expressed the lacZ reporter gene, it was shown that > 93% of cells present on the Ast-1 monolayers were motor neuron-like. Time-lapse analysis revealed that the precursors on the Ast-1 monolayers gave rise to neurons either directly or following a single cell division. Together, these results indicate that precursors in the murine spinal cord can be induced to differentiate into the motor neuron phenotype by factors produced by Ast-1 cells, suggesting that a similar factor(s) produced by cells akin to Ast-1 may regulate motor neuron differentiation in vivo. Images Fig. 2 Fig. 3 Fig. 5 PMID:7479730

Richards, L J; Murphy, M; Dutton, R; Kilpatrick, T J; Puche, A C; Key, B; Tan, S S; Talman, P S; Bartlett, P F

1995-01-01

270

Enhancement of polycarbonate membrane permeability due to plasma polymerization precursors  

NASA Astrophysics Data System (ADS)

The diffusivity of different species through a membrane depends on several factors to illustrate the structure of the matrix, molecular size and concentration of the species and temperature. This study concerns the use of the low-pressure plasma process with different monomers to confer surface chemical character to polycarbonate membranes without altering their bulk properties for change membrane permeability. Track-etched polycarbonate membranes with 0.03 ?m pore sizes were modified by plasma polymerization technique with two precursors; acrylic acid and allylamine in radio frequency discharge at certain plasma process conditions (discharge power: 20 W, exposure time: 10 min, frequency: 13.56 MHz). The transport properties of model organic acid (citric acid) was studied through unmodified and modified polycarbonate membranes by using diffusion cell system. Such plasma treated membranes were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and surface energy changes were studied by static contact angle measurements. These results showed that the change of surface properties could be used to improve the transport properties of the target substrates. The diffusion of citric acid through plasma treated polycarbonate membrane was increased about 54.1 ± 3.5% with precursor: allylamine while it was decreased 48.7 ± 2.5% with precursor acrylic acid. It was observed that the presences of proper functional group (like amino) in surfaces of pores can raise the affinity to citric acid and improve its transport rate.

Çökeliler, Dilek

2013-03-01

271

Tropospheric Precursors of Sudden Stratospheric Warmings: Data-Constrained Simulations  

NASA Astrophysics Data System (ADS)

The external factors that cause sudden stratospheric warmings to occur in the Northern Hemisphere are not yet entirely understood. For example, recent studies have found that the Madden Julian Oscillation in tropical weather influences the occurence of sudden warmings, but the number of observed warmings is so small that it is difficult to establish statistical significance. Studies that focus on single sudden warming events generally rely on reanalysis data and are therefore unable to separate the different factors influencing sudden warmings. On the other hand, studies that composite over many warming events in a climate model simulation can be difficult to interpret because individual events vary greatly from one another in their precursors, magnitude, downward-propagation, and lifecycle. We present a modeling framework that makes it possible to study individual winters by constraining the model's dynamical variables to observations using an Ensemble Kalman Filter. The ensemble filter is advantageous because it gives not just an estimate of the atmospheric state, but also of the probability distribution of the state variables, conditioned upon the available meteorological observations. We show that the tropical precursors of sudden warmings can be observed in variations in the rotation rate of the Earth, while extratropical precursors can be observed in variations in polar motion. This makes it possible to evaluate the degree to which observations are able to truly constrain the winter precurors of sudden warmings, by comparing the model's atmospheric angular momentum to observations of Earth rotation parameters.

Neef, Lisa; Matthes, Katja

2014-05-01

272

A committed hemopoietic precursor to innate lymphoid cells  

PubMed Central

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

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

2014-01-01

273

Thermogravimetric evaluation of the suitability of precursors for MOCVD  

NASA Astrophysics Data System (ADS)

A method based on the Langmuir equation for the estimation of vapour pressure and enthalpy of sublimation of subliming compounds is described. The variable temperature thermogravimetric/differential thermogravimetric (TG/DTG) curve of benzoic acid is used to arrive at the instrument parameters. Employing these parameters, the vapour pressure-temperature curves are derived for salicylic acid and camphor from their TG/DTG curves. The values match well with vapour pressure data in the literature, obtained by effusion methods. By employing the Clausius-Clapeyron equation, the enthalpy of sublimation could be calculated. Extending the method further, two precursors for metal-organic chemical vapour deposition (MOCVD) of titanium oxide bis-isopropyl bis tert-butyl 2-oxobutanoato titanium, Ti(OiPr)2(tbob)2, and bis-oxo-bis-tertbutyl 2-oxobutanoato titanium, [TiO(tbob)2]2, have been evaluated. The complex Ti(OiPr)2(tbob)2 is found to be a more suitable precursor. This approach can be helpful in quickly screening for the suitability of a compound as a CVD precursor.

Kunte, G. V.; Shivashankar, S. A.; Umarji, A. M.

2008-02-01

274

Development of techniques for tagging precursor and essential chemicals  

SciTech Connect

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

Swansiger, W.A.; Shepodd, T.J. [Sandia National Labs., Livermore, CA (United States); Phillips, M.L.F. [Sandia National Labs., Albuquerque, NM (United States)

1994-01-01

275

Spinal Cord Neuronal Precursors Generate Multiple Neuronal Phenotypes in Culture  

PubMed Central

Neuronal restricted precursors (NRPs) (Mayer-Proschel et al., 1997) can generate multiple neurotransmitter phenotypes during maturation in culture. Undifferentiated E-NCAM+ (embryonic neural cell adhesion molecule) immunoreactive NRPs are mitotically active and electrically immature, and they express only a subset of neuronal markers. Fully mature cells are postmitotic, process-bearing cells that are neurofilament-M and synaptophysin immunoreactive, and they synthesize and respond to different subsets of neurotransmitter molecules. Mature neurons that synthesize and respond to glycine, glutamate, GABA, dopamine, and acetylcholine can be identified by immunocytochemistry, RT-PCR, and calcium imaging in mass cultures. Individual NRPs also generate heterogeneous progeny as assessed by neurotransmitter response and synthesis, demonstrating the multipotent nature of the precursor cells. Differentiation can be modulated by sonic hedgehog (Shh) and bone morphogenetic protein (BMP)-2/4 molecules. Shh acts as a mitogen and inhibits differentiation (including cholinergic differentiation). BMP-2 and BMP-4, in contrast, inhibit cell division and promote differentiation (including cholinergic differentiation). Thus, a single neuronal precursor cell can differentiate into multiple classes of neurons, and this differentiation can be modulated by environmental signals. PMID:9742154

Kalyani, Anjali J.; Piper, David; Mujtaba, Tahmina; Lucero, Mary T.; Rao, Mahendra S.

2010-01-01

276

GABA Release and Uptake Regulate Neuronal Precursor Migration in the Postnatal Subventricular Zone  

Microsoft Academic Search

In the postnatal subventricular zone (SVZ), astrocyte-like cells tightly encapsulate chains of migrating neuronal precursors, although an influence of the astrocyte-like cells on precursor migration has not yet been demonstrated. Cell migration was studied in acute sagittal brain slices to determine whether GABA signaling between astrocyte-like cells and neuronal precursors controls the speed of neuronal precursor migration in the anterior

Anna J. Bolteus; Angelique Bordey

2004-01-01

277

Nucleotide sequence of cloned cDNA for bovine corticotropin-beta-lipotropin precursor  

Microsoft Academic Search

The nucleotide sequence of a 1,091-base pair cloned cDNA insert encoding bovine corticotropin-beta-lipotropin precursor mRNA is reported. The corresponding amino acid sequence indicates that the precursor protein consists of repetitive units and includes a third melanotropin sequence in its cryptic portion. Pairs of lysine and arginine residues separate the component peptides of the precursor.

Shigetada Nakanishi; Akira Inoue; Toru Kita; Masahiro Nakamura; Annie C. Y. Chang; Stanley N. Cohen; Shosaku Numa

1979-01-01

278

The influence of the group V/III molar precursor ratio on the structural properties  

E-print Network

, the precursors were temporally embedded in a nitrogen carrier gas stream, such that the total flow and pressureThe influence of the group V/III molar precursor ratio on the structural properties of InGaN layers, University of California, Irvine, CA 92697-2375, USA The influence of the group V/III molar precursor ratio

Dietz, Nikolaus

279

Chemokine GRO1 and the Spatial and Temporal Regulation of Oligodendrocyte Precursor Proliferation  

Microsoft Academic Search

Oligodendrocyte precursor proliferation is precisely regulated spatially and temporally during development to allow optimal myelination of the central nervous system (CNS). We propose that a paracrine regulatory pathway involving the chemokine GRO1 and platelet-derived growth factor (PDGF) permit local control of precursor proliferation in the brain. GRO1, PDGF, and their receptors act synergistically to precisely regulate oligodendrocyte precursor proliferation in

Shenandoah Robinson; Linda A. Franic

2001-01-01

280

Functional Analysis of Precursors for Serious Problem Behavior and Related Intervention  

ERIC Educational Resources Information Center

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…

Langdon, Nancy A.; Carr, Edward G.; Owen-DeSchryver, Jamie S.

2008-01-01

281

TRANSIENT BEHAVIOUR OF TROPOSPHERIC OZONE PRECURSORS IN A GLOBAL 3-D CTM AND THEIR INDIRECT  

E-print Network

, following the emission of pulses of the short-lived tropospheric ozone precursor species, methane, carbon hemispheres. Global warming potentials were derived for each of the short-lived tropospheric ozone precursor recognised that the emissions of a number of short-lived tropospheric ozone precursor species exert

282

Preparation of Bi-Sr-Ca-Cu-O superconductors from oxide-glass precursors  

DOEpatents

A superconductor and precursor therefor from oxide mixtures of Ca, Sr, Bi and Cu. Glass precursors quenched to elevated temperatures result in glass free of crystalline precipitates having enhanced mechanical properties. Superconductors are formed from the glass precursors by heating in the presence of oxygen to a temperature below the melting point of the glass.

Hinks, David G. (Lemont, IL); Capone, II, Donald W. (Northbridge, MA)

1992-01-01

283

Progressing from Identification and Functional Analysis of Precursor Behavior to Treatment of Self-Injurious Behavior  

ERIC Educational Resources Information Center

This multiple-study experiment evaluated the utility of assessing and treating severe self-injurious behavior (SIB) based on the outcomes of a functional analysis of precursor behavior. In Study 1, a precursor to SIB was identified using descriptive assessment and conditional probability analyses. In Study 2, a functional analysis of precursor

Dracobly, Joseph D.; Smith, Richard G.

2012-01-01

284

The effect of corticosteroids on amyloid beta precursor protein/amyloid precursor-like protein expression and processing in vivo.  

PubMed

In this study, we have investigated the effect of altered corticosteroid levels on the expression and processing of the amyloid beta precursor protein (A betaPP) and its amyloid precursor-like protein (APLP) homologue in rat brain. Four groups of animals were used in the study: sham operated, adrenalectomised, and adrenalectomised treated with either dexamethasone or aldosterone, with the A betaPP/APLP expression being determined by western blot analysis. While there were no changes in the levels of A betaPP/APLP following adrenalectomy, treatment with dexamethasone, but not aldosterone, resulted in a marked increase in protein expression levels with the level of increase varying between the brain regions examined. Corticosteroids had a more marked effect on the particulate rather than the soluble form of the protein, thus suggesting that elevated glucocorticoids may also be adversely influencing A betaPP/APLP processing. PMID:10586975

Budas, G; Coughlan, C M; Seckl, J R; Breen, K C

1999-11-26

285

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

PubMed

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

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

2011-03-01

286

Possibility to study ionospheric earthquakes precursors using CubeSats  

NASA Astrophysics Data System (ADS)

It is generally accepted that the earthquakes (EQ) are the most dangerous natural phenomena leading to the multiple losses in human lives and economics. The space observations must be included into the global chain of the EQ precursors monitoring at least as the initial warning to pay greater attention to the ground segment data. As the common opinion agrees, only in combination of multiple observation sites and set of monitored parameters the further progress at the way to raise EQ precursors detection probability may be obtained. There is necessary to answer two important questions before to plan any experiment to study ionospheric precursors of EQ. First one - whether the variations in the ionosphere definitely connected with the EQ preparation process do exist, and the second one - if they do, whether using these signals the precursors of EQ can be reliably identified and used for, if not prediction, then for the warning that the EQ in the given area approaches. The first successful mission dedicated to this problem solution was DEMETER (in orbit during more than 6 years from June 2004 until December 2010). The statistics of this study is impressive: altogether, about 9000 EQs with magnitude larger than M = 5.0 and depth lower than 40 km occurred all over the world during the analyzed period. In the result, the conclusion made there suggests that, obviously, there are real perturbations in the ionosphere connected with the seismic activity, but they are rather weak and at the present stage of data processing may be revealed only with the help of statistical analysis. To realize the study of ionospheric precursors, first it is imperative to clarify the mechanism of energy transfer along the chain “lithosphere-atmosphere-ionosphere”. Many hypotheses of such a mechanism exist, from which the mostly supported are fair weather currents (FWC) and atmospheric gravity waves (AGW), both of which have their pros and contras. The following minimal set of physical values may be advisable to measure to study them: if for FWC - electrons density and temperature and electric field variations, if for AGW - neutral particles concentration and magnetic fields variations, and TEC variations and thermal anomalies at the Earth’s surface and in the atmosphere for both. Also it became clear that the monitoring has to be made minimum in two, better in three points, preferably with the possibility to control the distance between them. This will increase the possibility to extract the seismogenic variations, being mostly local, at the background of the variations of other nature, being mostly enough spacious or even global. Taking into account the present and predictable reduction of the expenses for space scientific research, it would be extremely important to realize such a multi-point mission using the cheapest carriers - nanosatellites, especially cubesats. The analysis of both aspects of this problem - FWC and AGW mechanisms validation and the availability of miniaturized but enough sensitive scientific instrumentation, able to operate onboard cubesats, is made in the report. It shows that the scientific payload creation to realize the given task with the cubesats swarm is possible, including mini-thrusters able realizing the cubesats maneuvers on the orbit to control the distance between satellites. This allows us to come to conclusion that the realization of the cubesat project dedicated to the further study of important problem - detection of EQ precursors from space - may be put into practice at the present step of space science and technology development. Both necessary conditions - existence of scientific and experimental substantiation and of corresponding nanosatellite technology - are fulfilled. These works were partially supported by SSAU Contract No 1-16/12 and EC Framework 7 funded project 312993.

Korepanov, Valery; Lappas, Vaios

287

Prediction of Gene Network Models in Limb Muscle Precursors  

PubMed Central

The ventrolateral dermomyotome gives rise to all muscles of the limbs through the delamination and migration of cells into the limb buds. These cells proliferate and form myoblasts, withdraw from the cell cycle and become terminally differentiated. The myogenic lineage colonizes pre-patterned regions to form muscle anlagen as muscle fibers are assembled. The regulatory mechanisms that control the later steps of this myogenic program are not well understood. The homeodomain transcription factor Pitx2 is expressed in the muscle lineage from the migration of precursors to adult muscle. Ablation of Pitx2 results in distortion, rather than loss, of limb muscle anlagen, suggesting that its function becomes critical during the colonization of, and/or fiber assembly in, the anlagen. Gene expression arrays were used to identify changes in gene expression in flow-sorted migratory muscle precursors, labeled by Lbx1EGFP, which resulted from the loss of Pitx2. Target genes of Pitx2 were clustered using the “David Bioinformatics Functional Annotation Tool” to bin genes according to enrichment of gene ontology keywords. This provided a way to both narrow the target genes and identify potential gene families regulated by Pitx2. Representative target genes in the most enriched bins were analyzed for the presence and evolutionary conservation of Pitx2 consensus binding sequence, TAATCY, on the ?20kb, intronic, and coding regions of the genes. Fifteen Pitx2 target genes were selected based on the above analysis and were identified as having functions involving cytoskeleton organization, tissue specification, and transcription factors. Data from these studies suggest that Pitx2 acts to regulate cell motility and expression of muscle specific genes in the muscle precursors during forelimb muscle development. This work provides a framework to develop the gene network leading to skeletal muscle development, growth and regeneration. PMID:22917675

Campbell, Adam L; Eng, Diana; Gross, Michael K; Kioussi, Chrissa

2012-01-01

288

Accident Precursor Analysis and Management: Reducing Technological Risk Through Diligence  

NASA Technical Reports Server (NTRS)

Almost every year there is at least one technological disaster that highlights the challenge of managing technological risk. On February 1, 2003, the space shuttle Columbia and her crew were lost during reentry into the atmosphere. In the summer of 2003, there was a blackout that left millions of people in the northeast United States without electricity. Forensic analyses, congressional hearings, investigations by scientific boards and panels, and journalistic and academic research have yielded a wealth of information about the events that led up to each disaster, and questions have arisen. Why were the events that led to the accident not recognized as harbingers? Why were risk-reducing steps not taken? This line of questioning is based on the assumption that signals before an accident can and should be recognized. To examine the validity of this assumption, the National Academy of Engineering (NAE) undertook the Accident Precursors Project in February 2003. The project was overseen by a committee of experts from the safety and risk-sciences communities. Rather than examining a single accident or incident, the committee decided to investigate how different organizations anticipate and assess the likelihood of accidents from accident precursors. The project culminated in a workshop held in Washington, D.C., in July 2003. This report includes the papers presented at the workshop, as well as findings and recommendations based on the workshop results and committee discussions. The papers describe precursor strategies in aviation, the chemical industry, health care, nuclear power and security operations. In addition to current practices, they also address some areas for future research.

Phimister, James R. (Editor); Bier, Vicki M. (Editor); Kunreuther, Howard C. (Editor)

2004-01-01

289

L-deprenyl protects injured retinal precursor cells in vitro.  

PubMed

We evaluated the ability of L-deprenyl, a monoamine oxidase B-inhibitor (MAO-B), to preserve the viability of serum-deprived immortalized retinal precursor cells in vitro. We serum-deprived rat neural retinal ganglion cells immortalized by an incompetent retro virus. We instilled L-deprenyl in concentrations ranging from 0.01 to 100 microM. After 72 hours we performed a cell count of the L-deprenyl cultures and the control (no L-deprenyl instilled) with a hemocytometer and flow cytometry. We used transmission electron microscopy, DNA gel electrophoresis, and flow cytometry to determine the mechanism of cell death. This study showed that all five concentrations of L-deprenyl statistically increased the survival rate of immortalized retinal precursor cells at 72 hours in the serum-deprived medium (P = 0.01, ANOVA test). Ten microM and higher appeared to provide the greatest immortalized retinal precursor cell survival (12.7 x 10(-4) cells) compared to the control (5.8 x 10(-4) cells). Flow cytometry also demonstrated a higher percentage of surviving cells at 10 microM (80%) and 100 microM (76%) than with the control (58%) (P = 0.0017, chi2 test). Transmission electron microscopy, DNA electrophoresis, and flow cytometry showed that the mode of cell death was by apoptosis. This study suggests that L-deprenyl may be worthy of further investigation as a neuroprotective agent to treat chronic open-angle glaucoma. PMID:9326730

Ragaiey, T; Ma, J X; Jiang, W J; Greene, W; Seigel, G M; Stewart, W C

1997-10-01

290

Cell Adhesion Signaling Regulates RANK Expression in Osteoclast Precursors  

PubMed Central

Cells with monocyte/macrophage lineage expressing receptor activator of NF-?B (RANK) differentiate into osteoclasts following stimulation with the RANK ligand (RANKL). Cell adhesion signaling is also required for osteoclast differentiation from precursors. However, details of the mechanism by which cell adhesion signals induce osteoclast differentiation have not been fully elucidated. To investigate the participation of cell adhesion signaling in osteoclast differentiation, mouse bone marrow-derived macrophages (BMMs) were used as osteoclast precursors, and cultured on either plastic cell culture dishes (adherent condition) or the top surface of semisolid methylcellulose gel loaded in culture tubes (non-adherent condition). BMMs cultured under the adherent condition differentiated into osteoclasts in response to RANKL stimulation. However, under the non-adherent condition, the efficiency of osteoclast differentiation was markedly reduced even in the presence of RANKL. These BMMs retained macrophage characteristics including phagocytic function and gene expression profile. Lipopolysaccharide (LPS) and tumor necrosis factor –?TNF-? activated the NF-?B-mediated signaling pathways under both the adherent and non-adherent conditions, while RANKL activated the pathways only under the adherent condition. BMMs highly expressed RANK mRNA and protein under the adherent condition as compared to the non-adherent condition. Also, BMMs transferred from the adherent to non-adherent condition showed downregulated RANK expression within 24 hours. In contrast, transferring those from the non-adherent to adherent condition significantly increased the level of RANK expression. Moreover, interruption of cell adhesion signaling by echistatin, an RGD-containing disintegrin, decreased RANK expression in BMMs, while forced expression of either RANK or TNFR-associated factor 6 (TRAF6) in BMMs induced their differentiation into osteoclasts even under the non-adherent condition. These results suggest that cell adhesion signaling regulates RANK expression in osteoclast precursors. PMID:23139818

Mochizuki, Ayako; Takami, Masamichi; Miyamoto, Yoichi; Nakamaki, Tsuyoshi; Tomoyasu, Shigeru; Kadono, Yuho; Tanaka, Sakae; Inoue, Tomio; Kamijo, Ryutaro

2012-01-01

291

Radiative precursors driven by converging blast waves in noble gases  

NASA Astrophysics Data System (ADS)

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.

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

292

Persistence of perfluoroalkyl acid precursors in AFFF-impacted groundwater and soil.  

PubMed

Several classes of polyfluorinated chemicals that are potential precursors to the perfluorinated carboxylates and sulfonates are present in aqueous film-forming foams (AFFF). To assess the persistence of these AFFF-derived precursors, groundwater, soil, and aquifer solids were obtained in 2011 from an unlined firefighter training area at a U.S. Air Force Base where AFFF was regularly used between 1970 and 1990. To measure the total concentration of perfluorinated carboxylate and sulfonate precursors in archived AFFF formulations and AFFF-impacted environmental samples, a previously developed assay that uses hydroxyl radical to oxidize precursors to perfluorinated carboxylates was adapted for these media. This assay was employed along with direct measurement of 22 precursors found in AFFF and a suite of other poly- and perfluoroalkyl substances (PFASs). On a molar basis, precursors accounted for 41-100% of the total concentration of PFASs in archived AFFF formulations. In the training area, precursors measured by the oxidation assay accounted for an average of 23% and 28% of total PFASs (i.e., precursors and perfluorinated carboxylates and sulfonates) in groundwater and solids samples, respectively. One precursor in AFFF, perfluorohexane sulfonamide amine, was observed on several highly contaminated soil and aquifer solids samples, but no other precursors present in AFFF formulations were detected in any samples at this field site. Suspected intermediate transformation products of precursors in AFFF that were directly measured accounted for approximately half of the total precursor concentration in samples from the training site. The fraction of PFASs consisting of perfluorinated carboxylates and sulfonates was greater in groundwater and solid samples than in any archived AFFF formulations, suggesting that much of the mass of precursors released at the site was converted to perfluorinated carboxylates and sulfonates. The precursors that have persisted at this site may generate significant amounts of additional perfluorinated carboxylates and sulfonates upon remediation of contaminated groundwater or aquifer solids. PMID:23886337

Houtz, Erika F; Higgins, Christopher P; Field, Jennifer A; Sedlak, David L

2013-08-01

293

Polymer precursors for SiC ceramic materials  

NASA Technical Reports Server (NTRS)

Work on precursor polymers to SiC was performed, concentrating on polymers made from decamethyl cyclohexasilyene units. The initial approach was to synthesize mixed diphenyl decamethyl cyclohexasilane, dephenylate, and polymerize. This produced polymers which had yields of up to 50 percent SiC. (Theoretical yield is 75 percent). The present approach is to make the polymer through the intermediate trans-1,4-diphenyl decamethyl cyclohexasilane. This should produce a crystalline polymer and high strength fibers. These will be thermally decomposed to SiC fibers. This requires new chemistry which is currently being studied.

Litt, Morton H.

1986-01-01

294

Lunar Precursor Robotic Program: A Robotic Focus To The Vision  

NASA Technical Reports Server (NTRS)

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.

French, Raymond A.; Nall, Mark E.

2007-01-01

295

Evolution from amino acids - Lunar occurrence of their precursors.  

NASA Technical Reports Server (NTRS)

Review of the present state of experimentally based concepts of organic evolution from amino acids. Earlier studies of the synthesis of amino acid precursors from meteoritic material, lunar dust, and terrestrial lava are briefly summarized, and laboratory experiments in which polymers of amino acids were obtained either by direct heating of dry amino acids or by heating aqueous solutions of mixtures of amino acids are described. In particular, a process is described by which alpha-amino acids were made to react to form linear chains of proteinoids. It is concluded that a proteinoid microsystem was a common ancestor of all life on earth.

Fox, S. W.

1972-01-01

296

Nesting induced precursor effects: a renormalization group approach.  

PubMed

We develop a controlled weak coupling renormalization group (RG) approach to itinerant electrons. Within this formalism we rederive the phase diagram for two-dimensional non-nested systems. We then study how nesting modifies this phase diagram. We show that competition between particle-particle and particle-hole channels leads to the manifestation of an unstable precursor fixed point in the RG flow. This effect should be experimentally measurable, and may be relevant for an explanation of pseudogaps in the high temperature superconductors, as a crossover phenomenon. PMID:11290059

Vistulo De Abreu, F; Douçot, B

2001-03-26

297

Transmembrane transport of peptidoglycan precursors across model and bacterial membranes  

Microsoft Academic Search

Translocation of the peptidoglycan precursor Lipid II\\u000aacross the cytoplasmic membrane is a key step in\\u000abacterial cell wall synthesis, but hardly understood.\\u000aUsing NBD-labelled Lipid II, we showed by fluorescence\\u000aand TLC assays that Lipid II transport does not\\u000aoccur spontaneously and is not induced by the presence\\u000aof single spanning helical transmembrane\\u000apeptides that facilitate transbilayer movement of

Vincent van Dam; Robert Sijbrandi; Matthijs Kol; Ewa Swiezewska; Ben de Kruijff; Eefjan Breukink

2007-01-01

298

Mathematical approach to thermolysin-catalyzed synthesis of aspartame precursor  

Microsoft Academic Search

Aspartame precursor (N-(benzyloxycarbonyl)-l-aspartyl-l-phenylalanine methyl ester), an artificial sweetener, was synthesized enzymatically from N-(benzyloxycarbonyl)-l-aspartic acid (Z-l-Asp) and l-phenylalanine methyl ester (l-PM) as substrates with thermolysin as an enzyme in an aqueous monophase system. A reversible Theorell-Chance mechanism is proposed to explain the synthesis, and its kinetic parameters were determined at pH 6.5 and 40°C. The rate equation of the enzymatic reaction,

Yoshihiko Murakami; Makoto Hirata; Akira Hirata

1996-01-01

299

Beryllium-10 in Australasian tektites - Evidence for a sedimentary precursor  

NASA Technical Reports Server (NTRS)

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.

Pal, D. K.; Moniot, R. K.; Kruse, T. H.; Herzog, G. F.; Tuniz, C.

1982-01-01

300

Methods of making copper selenium precursor compositions with a targeted copper selenide content and precursor compositions and thin films resulting therefrom  

DOEpatents

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.

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

301

Senile plaque neurites in Alzheimer disease accumulate amyloid precursor protein.  

PubMed Central

Senile plaques are polymorphous beta-amyloid protein deposits found in the brain in Alzheimer disease and normal aging. This beta-amyloid protein is derived from a larger precursor molecule of which neurons are the principal producers in brain. We found that amyloid precursor protein (APP)-immunoreactive neurites were involved in senile plaques and that only a subset of these neurites showed markers for the abnormal filaments characteristic of neurofibrillary pathology. In the neocortex of nondemented individuals with senile plaques but spared of neurofibrillary pathology, dystrophic neurites in senile plaques showed only APP accumulation. In contrast, in the brains of Alzheimer patients, virtually all APP-immunoreactive neurites also showed immunoreactivity with ubiquitin, tau, and phosphorylated neurofilaments. The presence of tau and neurofilament epitopes in dystrophic neurites in senile plaques was correlated with the extent of neurofibrillary pathology in the surrounding brain tissue. Accumulation of APP and the formation of neurofibrillary pathology in senile plaque neurites are therefore distinct phenomena. Our findings suggest that APP accumulation in senile plaque neurites occurs prior to tau accumulation and is therefore more closely related to appearance of neuritic dystrophy. Images PMID:1652752

Cras, P; Kawai, M; Lowery, D; Gonzalez-DeWhitt, P; Greenberg, B; Perry, G

1991-01-01

302

Prediction of MicroRNA Precursors Using Parsimonious Feature Sets  

PubMed Central

MicroRNAs (miRNAs) are a class of short noncoding RNAs that regulate gene expression through base pairing with messenger RNAs. Due to the interest in studying miRNA dysregulation in disease and limits of validated miRNA references, identification of novel miRNAs is a critical task. The performance of different models to predict novel miRNAs varies with the features chosen as predictors. However, no study has systematically compared published feature sets. We constructed a comprehensive feature set using the minimum free energy of the secondary structure of precursor miRNAs, a set of nucleotide-structure triplets, and additional extracted sequence and structure characteristics. We then compared the predictive value of our comprehensive feature set to those from three previously published studies, using logistic regression and random forest classifiers. We found that classifiers containing as few as seven highly predictive features are able to predict novel precursor miRNAs as well as classifiers that use larger feature sets. In a real data set, our method correctly identified the holdout miRNAs relevant to renal cancer. PMID:25392687

Stepanowsky, Petra; Levy, Eric; Kim, Jihoon; Jiang, Xiaoqian; Ohno-Machado, Lucila

2014-01-01

303

Precursor ionization ahead of strong shock waves in argon  

NASA Astrophysics Data System (ADS)

The mechanism of precursor ionization ahead of strong shock waves has been studied in a low density shock tube. The experimental results are illustrated with Arrhenius plots with kink points dividing them into two parts with apparent activation energy ratio 1:2, namely with the values 7.7 eV and 15.3 eV, and varying with first and third power of the density respectively. A model is proposed to interpret the facts where the process taking place in the precursor region, is a two step photo ionization accompanied with the drift flow effect of the gas relative to the shock wave or the ionization recombination effect according to whether the shock speed and initial density are low enough. The product of the A-A collision excitation cross section coefficient S * multiplied by the radiation cross section Q * of Argon S *× Q *=1×10-36 (cm4eV-1) and the three body recombination coefficient of Argon at room temperature k ra =1×10-24 (cm-6s-1).

Jiping, Cui; Bingcheng, Fan; Yuzhong, He

1993-11-01

304

Workshop on low-frequency electrical precursors to earthquakes  

NASA Astrophysics Data System (ADS)

An NSF-sponsored workshop entitled “Low-Frequency Electrical Precursors to Earthquakes: Fact or Fiction?” was held at the Lake Arrowhead Hilton in California from June 14 to 17. Thirty-seven scientists participated in a review of past and current experiments that began with a poster session followed by an open discussion. Highlights of research presented at this workshop included seismic electric signals from Greece, precursory changes of resistivity in China, a reassessment of the ULF anomaly at Loma Prieta, and identification of geophysical constraints for mechanisms possibly causing precursory signals.Discussion focused on instrumentation, laboratory studies, definition of anomalous signals, mechanisms, and the significance of correlations between anomalies and earthquakes. While much is still uncertain, some of the precursory phenomena exist and expanded measurement programs are warranted. The participants identified three main guidelines to improve and quantify their attempts to monitor electrical and electromagnetic precursors and to extend their understanding of the mechanisms responsible for the generation of precursory signals.

Park, Stephen K.

305

Synthesis of the flavour precursor, alliin, in garlic tissue cultures.  

PubMed

The path of synthesis of alkyl cysteine sulphoxides, or flavour precursors, in the Alliums is still speculative. There are two proposed routes for alliin biosynthesis, one is from serine and allyl thiol while the other is from glutathione and an allyl source via gamma glutamyl peptides. The routes have been investigated by exposing undifferentiated callus cultures of garlic and onion to potential pathway intermediates. After a period of incubation of 2 days the callus was extracted, and analysed for flavour precursors and related compounds by HPLC. Standards of alliin, isoallin and propiin were synthesised and their identity confirmed by HPLC and NMR. Putative intermediates selected included the amino acids serine and cysteine, as well as more complex intermediates such as allylthiol, allyl cysteine and glutathione. Both garlic and onion tissue cultures were able to synthesize alliin following incubation with allylthiol, and cysteine conjugates such as allyl cysteine. The ability of the tissue cultures to form alliin from intermediates was compatible with the proposed routes of synthesis of alliin. PMID:15652575

Hughes, J; Tregova, A; Tomsett, A B; Jones, M G; Cosstick, R; Collin, H A

2005-01-01

306

Coevaporated Cu-In films as precursors for solar cells  

NASA Astrophysics Data System (ADS)

We investigate Cu-In thin films used as precursors for the production of CuInS2 and Se2 solar-cell absorber material via reactive annealing. The films are produced by coevaporation of Cu and In onto glass substrates and are characterized by means of Rutherford backscattering and x-ray diffraction (XRD). The interplay of phase composition, morphology, and surface topography is studied as a function of chemical composition, substrate temperature, and annealing processes. The analysis of the XRD data is based on known crystallographic data for the phases Cu7In3 (? phase), Cu16In9 (?' phase), Cu11In9, and In. Refined crystallographic data for CuIn2 are presented, and the low-temperature modification of Cu16In9 (?-phase) is investigated by means of bulk powder samples. These data and the inclusion of texture effects allow us to perform a complete RIETVELD type analysis of the Cu-In precursors. It is shown that, in contrast to sequentially evaporated films, all known Cu-In equilibrium phases can be formed during film deposition. These are Cu7In3, Cu16In9, Cu11In9, and CuIn2. Moreover, it is found that single-phase films of all these phases can be produced. Film roughness is shown to increase with deposition temperature and In content. The results presented offer new prospects for sulfurization and selenization processes in solar-cell production.

Gossla, M.; Metzner, H.; Mahnke, H.-E.

1999-10-01

307

Soot precursor measurements in benzene and hexane diffusion flames  

SciTech Connect

To clarify the mechanism of soot formation in diffusion flames of liquid fuels, measurements of soot and its precursors were carried out. Sooting diffusion flames formed by a small pool combustion equipment system were used for this purpose. Benzene and hexane were used as typical aromatic and paraffin fuels. A laser-induced fluorescence (LIF) method was used to obtain spatial distributions of polycyclic aromatic hydrocarbons (PAHs), which are considered as soot particles. Spatial distributions of soot in test flames were measured by a laser-induced incandescence (LII) method. Soot diameter was estimated from the temporal change of LII intensity. A region of transition from PAHs to soot was defined from the results of LIF and LII. Flame temperatures, PAH species, and soot diameters in this transition region were investigated for both benzene and hexane flames. The results show that though the flame structures of benzene and hexane were different, the temperature in the PAHs-soot transition region of the benzene flame was similar to that of the hexane flame. Furthermore, the relationship between the PAH concentrations measured by gas chromatography in both flames and the PAH distributions obtained from LIF are discussed. It was found that PAHs with smaller molecular mass, such as benzene and toluene, remained in both the PAHs-soot transition and sooting regions, and it is thought that molecules heavier than pyrene are the leading candidates for soot precursor formation. (author)

Kobayashi, Y.; Furuhata, T.; Amagai, K.; Arai, M. [Department of Mechanical System Engineering, Graduate School of Engineering, Gunma University, 1-5-1 Tenjin-cho, Kiryu-shi, Gunma 376-8515 (Japan)

2008-08-15

308

Removal of small trihalomethane precursors from aqueous solution by nanofiltration.  

PubMed

The removal of small trihalomethane precursors (THMPs) from aqueous solution by two commercial nanofiltration membranes (NF70 and NF270) was investigated. Resorcinol, phloroglucinol, and 3-hydroxybenzoic acid were selected as model compounds of small THMPs, while tannic acid was chosen as a medium molecular disinfection by-product (DBP) precursor for comparison. The performance of nanofiltration membranes were evaluated by introducing polyethylene glycol (PEG) solutions and uncharged saccharides to estimate molecular weight cut-off (MWCO) and membrane pore radii, respectively. The streaming potential was measured to estimate the membrane surface charge at different pH values, which reveals that the NF270 membrane is more pH-sensitive than the NF70 membrane. The rejections of the above selected THMPs were assessed under various pH values, and the removal efficiencies of THMPs for both membranes at high pH values are reasonably well. Charge exclusion is the prevailing mechanism for the selected small model compounds retended by the negatively charged nanofiltration membranes, while size exclusion and adsorption are controlled mechanisms but not sufficient for the rejection of unionized small organic molecules. In general, the NF270 membrane exhibits the superior permeation rate value, which takes an advantage over the NF70 membrane from the aspect of energy conservation. PMID:17212977

Lin, Yi-Li; Chiang, Pen-Chi; Chang, E-E

2007-07-19

309

NeuroPID: a classifier of neuropeptide precursors.  

PubMed

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

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

2014-07-01

310

Microtubule-dependent redistribution of a cytoplasmic cornified envelope precursor.  

PubMed

Several cytoplasmic cornified envelope precursors have been described. Nevertheless, the mechanism whereby these proteins are positioned at the site of crosslink formation is not known. In this study, we examine the intracellular distribution of the cornified envelope precursor S100A11 (S100C) and the effects of the physiologic differentiating agent calcium on this distribution. S100A11 is localized in the cytoplasm of resting cultured human keratinocytes. Treatment with calcium causes S100A11 to relocate to the cell periphery. Immunoprecipitation studies reveal that S100A11 associates with microtubules, and inhibitor studies indicate that functional micro-tubules are required for S100A11 peripheral redistribution. Parallel studies indicate that S100A11 is not present in the Golgi or endoplasmic reticulum (ER), suggesting that S100A11 is not moved to the cell periphery via the classical Golgi/ER export pathway. Further evidence that the Golgi/ER is not involved is provided by the observation that the Golgi/ER disruptor brefeldin A does not alter movement. These results suggest that redistribution along microtubules is a mechanism whereby S100A11 is positioned at the cell periphery in preparation for transglutaminase-dependent crosslinking. Staining of epidermal tissue sections from uninvolved and psoriatic epidermis reveals strong staining at the cell periphery in the majority of suprabasal cells, confirming a peripheral distribution of S100A11 in vivo. PMID:14962086

Broome, Ann-Marie; Eckert, Richard L

2004-01-01

311

NeuroPID: a classifier of neuropeptide precursors  

PubMed Central

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

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

2014-01-01

312

An Accident Precursor Analysis Process Tailored for NASA Space Systems  

NASA Technical Reports Server (NTRS)

Accident Precursor Analysis (APA) serves as the bridge between existing risk modeling activities, which are often based on historical or generic failure statistics, and system anomalies, which provide crucial information about the failure mechanisms that are actually operative in the system and which may differ in frequency or type from those in the various models. These discrepancies between the models (perceived risk) and the system (actual risk) provide the leading indication of an underappreciated risk. This paper presents an APA process developed specifically for NASA Earth-to-Orbit space systems. The purpose of the process is to identify and characterize potential sources of system risk as evidenced by anomalous events which, although not necessarily presenting an immediate safety impact, may indicate that an unknown or insufficiently understood risk-significant condition exists in the system. Such anomalous events are considered accident precursors because they signal the potential for severe consequences that may occur in the future, due to causes that are discernible from their occurrence today. Their early identification allows them to be integrated into the overall system risk model used to intbrm decisions relating to safety.

Groen, Frank; Stamatelatos, Michael; Dezfuli, Homayoon; Maggio, Gaspare

2010-01-01

313

Engineering the Microstructure of Solution Precursor Plasma-Sprayed Coatings  

NASA Astrophysics Data System (ADS)

This study examines the fundamental reactions that occur in-flight during the solution precursor plasma spraying (SPPS) of solutions containing Zr- and Y-based salts in water or ethanol solvent. The effect of plasma jet composition (pure Ar, Ar-H2 and Ar-He-H2 mixtures) on the mechanical break-up and thermal treatment of the solution, mechanically injected in the form of a liquid stream, was investigated. Observation of the size evolution of the solution droplets in the plasma flow by means of a laser shadowgraphy technique, showed that droplet break-up was more effective and solvent evaporation was faster when the ethanol-based solution was injected into binary or ternary plasma gas mixtures. In contrast with water-based solutions, residual liquid droplets were always detected at the substrate location. The morphology and structure of the material deposited onto stainless steel substrates during single-scan experiments were characterised by SEM, XRD and micro-Raman spectroscopy and were shown to be closely related to in-flight droplet behaviour. In-flight pyrolysis and melting of the precursor led to well-flattened splats, whereas residual liquid droplets at the substrate location turned into non pyrolysed inclusions. The latter, although subsequently pyrolysed by the plasma heat during the deposition of entire coatings, resulted in porous "sponge-like" structures in the deposit.

Bertolissi, G.; Chazelas, C.; Bolelli, G.; Lusvarghi, L.; Vardelle, M.; Vardelle, A.

2012-12-01

314

Consideration of formation process for the nuclei on precursor  

NASA Astrophysics Data System (ADS)

The very isotropic microwave background and the Hubble expansion indicate that the universe has evolved from an earlier state of high temperature and density that can be reasonably well described by Friedman-Lemaitre-Robertson-Walker cosmological models. The nuclear evolution of non-degenerate matter expanding from very high temperature was studied in detail for various values of the expansion rate and of the proton-neutron abundance difference and baryon density[1,2,3]. In this calculation, many nuclear reactions were included, and its results suggested important reaction process for the evolution of nuclear abundances. 3He and 4He are very important elements in these nuclear reactions as the primordial nucleosynthesis. Microscopic study for few body system is one main topic in nuclear theoretical physics. In this field, very accurate calculations are available by using the Faddeev equations[4]. Recently, many data for pd, p-3He and d-3He have been obtained including polarized observables. Model calculations for systems including 3He and 4He (for example, d + 3He -> p + 4He) are carried out using the Faddeev equations based on the meson exchange models[4]. This model reproduces well the empirical phase shifts which are determined by so-called phase-shift analyses using all of available scattering data measured at various laboratories around the world[5,6,7]. Constructions of models for the nuclear reactions including 3He and 4He will give important information for calculations of the primordial nucleosynthesis after big-ban. The calculations are carried out until the sum of the abundances at each mass number ceases to change. Various different set of initial conditions for the baryon mass density, the expansion rate and the neutron-proton ratio are used. Dusts kept in precursor asteroid nebular form precursor asteroid, then, formations of planet start [8]. Possible values of parameters in the initial conditions for theoretical calculations will be searched considering an information from precursor asteroid References: {[1]} R. V. Wagoner, W. A. Fowler and F. Hoyle (1967), Astrophys. J. 148, 3. {[2]} R. V. Wagoner. (1969), Astrophys. J. 162, 247. [3] R. V. Wagoner (1973), Astrophys. J. 179, 343. [4] For example, S. Gojyuki and S. Oryu (2003), Mod. Phys. Lett. A18, 302. [5] Y. Yoshino, V. Limkaisang, J. Nagata, H. Yoshino and M. Matsuda (2000), Prog. Theor. Phys. 103, 107. [6] H. Yoshino, J. Nagata, V. Limkaisang, Y. Yoshino, M. Matsuda (2001), Nucl. Phys. A684, 615c. [7] H. Yoshino, H. Kazuo, M. Matsuda, J. Nagata, (2003), Mod. Phys. Lett. A18, 444. [8] Hayashi, C. et. al., 1985, Protostars and Planets, Univ. of Arizona Press, pp. 1100.

Nagata, J.; Okamoto, M.

2003-12-01

315

Comparative examination of titania nanocrystals synthesized by peroxo titanic acid approach from different precursors.  

PubMed

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

Liu, Yong-Jun; Aizawa, Mami; Wang, Zheng-Ming; Hatori, Hiroaki; Uekawa, Naofumi; Kanoh, Hirofumi

2008-06-15

316

Single-source precursors for ternary chalcopyrite materials, and methods of making and using the same  

NASA Technical Reports Server (NTRS)

A single source precursor for depositing ternary I-III-VI.sub.2 chalcopyrite materials useful as semiconductors. The single source precursor has the I-III-VI.sub.2 stoichiometry built into a single precursor molecular structure which degrades on heating or pyrolysis to yield the desired I-III-VI.sub.2 ternary chalcopyrite. The single source precursors effectively degrade to yield the ternary chalcopyrite at low temperature, e.g. below 500.degree. C., and are useful to deposit thin film ternary chalcopyrite layers via a spray CVD technique. The ternary single source precursors according to the invention can be used to provide nanocrystallite structures useful as quantum dots. A method of making the ternary single source precursors is also provided.

Banger, Kulbinder K. (Inventor); Hepp, Aloysius F. (Inventor); Harris, Jerry D. (Inventor); Jin, Michael Hyun-Chul (Inventor); Castro, Stephanie L. (Inventor)

2006-01-01

317

Monitoring Precursor 16S rRNAs of Acinetobacter spp. in Activated Sludge Wastewater Treatment Systems  

Microsoft Academic Search

Recently, Cangelosi and Brabant used oligonucleotide probes targeting the precursor 16S rRNA of Esche- richia coli to demonstrate that the levels of precursor rRNA were more sensitive to changes in growth phase than the levels of total rRNA (G. A. Cangelosi and W. H. Brabant, J. Bacteriol. 179:4457-4463, 1997). In order to measure changes in the levels of precursor rRNA

DANIEL B. OERTHER; JAKOB PERNTHALER; ANDREAS SCHRAMM; RUDOLF AMANN; LUTGARDE RASKIN

2000-01-01

318

N-sulfinylcarbamate-pentacene adduct: A novel pentacene precursor soluble in alcohols  

Microsoft Academic Search

A novel pentacene precursor was synthesized by Diels-Alder reaction of pentacene and N-sulfinylbutylcarbamate. The adduct is highly soluble in isopropyl and higher alcohols and moderately soluble in ethanol and methanol. This precursor undergoes retro-Diels-Alder reaction in solid phase at low temperatures to give pentacene. Organic thin film transistors with pentacene channels obtained by solution deposition of this novel precursor from

A. Afzali; C. R. Kagan; G. P. Traub

2005-01-01

319

Improved Precursor Chemistry for the Synthesis of III-V Quantum Dots  

PubMed Central

The synthesis of III-V Quantum Dots has been long known to be more challenging than the synthesis of other types of inorganic quantum dots. This is attributed to highly reactive group-V precursors. We synthesized molecules that are suitable for use as group-V precursors and characterized their reactivity using multiple complementary techniques. We show that the size distribution of indium arsenide quantum dots indeed improves with decreased precursor reactivity. PMID:23228014

Harris, Daniel K.; Bawendi, Moungi G.

2012-01-01

320

Patterning polymer metal precursors for high temperature superconducting Bi-Sr-Ca-Cu-O-films  

SciTech Connect

Bi-Sr-Ca-Cu-O HTSC thin films were prepared from polymer metal precursors in a special annealing procedure. The precursor films can be patterned before the annealing process in which the superconducting phase is generated. The authors have investigated the patterning of precursor films by UV radiation, and the thermal degradation process by thermogravimetry and mass spectroscopy. The HTSC films were characterized by X-ray diffraction and electrical resistivity measurements.

von Lampe, I.; Goetze, S.; Zygalsky, F. [Institut fuer Anorganische und Analytische Chemie, Berlin (Germany)

1996-12-01

321

Novel inorganic\\/organic hybrid materials based on blown soybean oil with sol–gel precursors  

Microsoft Academic Search

New ceramer coatings based on blown soybean oil with sol–gel precursors were prepared and evaluated as a function of the blowing process and sol–gel precursors content. Soybean oils were blown at three different rates in order to optimize the blowing process. Three sol–gel precursors, titanium (IV) i-propoxide, titanium (IV) di-i-propoxide bis-acetoacetonate, and zirconium n-propoxide were then used with the blown

Ganghua Teng; Joseph R Wegner; Greta J Hurtt; Mark D Soucek

2001-01-01

322

Improved anthraquinone accumulation in cell cultures of Cinchona `Robusta' by feeding of biosynthetic precursors and inhibitors  

Microsoft Academic Search

The effects of feeding of biosynthetic precursors and pathway specific inhibitors on anthraquinone (AQ) accumulation in fungal elicited cell cultures of Cinchona`Robusta' were studied. Addition of glyceraldehyde (1 mM), the initial precursor in the methyl-d-erythritol 4-phosphate (MEP) pathway, did not increase AQ accumulation, suggesting that the endogenous level of this precursor is not a limiting factor of AQ flux. It

Ying-Shan Han; Robert van der Heijden; Robert Verpoorte

2002-01-01

323

The influence of short-lived ozone precursor emissions on radiative climate forcing  

Microsoft Academic Search

Reductions in short-lived ozone precursor emissions change tropospheric ozone and methane concentrations, influencing global climate through the radiative budget of the atmosphere. Unlike long-lived greenhouse gases, the radiative forcing (RF) due to ozone depends on the location of its precursor emissions. We assess the effects of 20% reductions in anthropogenic ozone precursor emissions (nitrogen oxides, carbon monoxide, and non-methane volatile

M. M. Fry; V. Naik; J. J. West; M. D. Schwarzkopf; A. M. Fiore

2010-01-01

324

Electrochemical behavior of carbon aerogels derived from different precursors  

SciTech Connect

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.

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

325

Structural precursor to freezing: An integral equation study  

E-print Network

Recent simulation studies have drawn attention to the shoulder which forms in the second peak of the radial distribution function of hard-spheres at densities close to freezing and which is associated with local crystalline ordering in the dense fluid. We address this structural precursor to freezing using an inhomogeneous integral equation theory capable of describing local packing constraints to a high level of accuracy. The addition of a short-range attractive interaction leads to a well known broadening of the fluid-solid coexistence region as a function of attraction strength. The appearence of a shoulder in our calculated radial distribution functions is found to be consistent with the broadened coexistence region for a simple model potential, thus demonstrating that the shoulder is not exclusively a high density packing effect.

J. M. Brader

2008-08-01

326

Tilt precursors before earthquakes on the San Andreas fault, California  

USGS Publications Warehouse

An array of 14 biaxial shallow-borehole tiltmeters (at 10-7 radian sensitivity) has been installed along 85 kilometers of the San Andreas fault during the past year. Earthquake-related changes in tilt have been simultaneously observed on up to four independent instruments. At earthquake distances greater than 10 earthquake source dimensions, there are few clear indications of tilt change. For the four instruments with the longest records (>10 months), 26 earthquakes have occurred since July 1973 with at least one instrument closer than 10 source dimensions and 8 earthquakes with more than one instrument within that distance. Precursors in tilt direction have been observed before more than 10 earthquakes or groups of earthquakes, and no similar effect has yet been seen without the occurrence of an earthquake.

Johnston, M. J. S.; Mortensen, C. E.

1974-01-01

327

Teleseismic search for slow precursors to large earthquakes.  

PubMed

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

Ihmlé, P F; Jordan, T H

1994-12-01

328

Is there a field-theoretic explanation for precursor biopolymers?  

PubMed

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

Rosen, Gerald

2002-08-01

329

Slippage of 4He Films and Precursor Phenomenon of Superfluidity  

NASA Astrophysics Data System (ADS)

We have carried out quartz crystal microbalance (QCM) experiments for 4He films on an exfoliated single-crystalline graphite using a 32 kHz tuning fork, and have measured the temperature dependence of the resonance frequency and the Q value for various areal densities and oscillation amplitudes. Comparing with the previous experiments for Grafoil, the decoupling of the films due to the slippage or the superfluidity was larger than that of Grafoil, and the competition between the slippage and the superfluidity was observed in three-atom thick films. Furthermore, it was found that the slippage is suppressed gradually at higher temperature than the superfluid onset T c , and that the relaxation time decreases at low temperatures while it obeys the Arrhenius law at high temperatures. These results suggest a precursor to the superfluidity of 4He films.

Noda, Kei; Okamura, Ko; Taniguchi, Junko; Suzuki, Masaru; Hieda, Mitsunori

2013-06-01

330

Tilt Precursors before Earthquakes on the San Andreas Fault, California.  

PubMed

An array of 14 biaxial shallow-borehole tiltmeters (at 1O(-7) radian sensitivity) has been installed along 85 kilometers of the San Andreas fault during the past year. Earthquake-related changes in tilt have been simultaneously observed on up to four independent instruments. At earthquake distances greater than 10 earthquake source dimensions, there are few clear indications of tilt change. For the four instruments with the longest records (> 10 months), 26 earthquakes have occurred since July 1973 with at least one instrument closer than 10 source dimensions and 8 earthquakes with more than one instrument within that distance. Precursors in tilt direction have been observed before more than 10 earthquakes or groups of earthquakes, and no similar effect has yet been seen without the occurrence of an earthquake. PMID:17843056

Johnston, M J; Mortensen, C E

1974-12-13

331

Hybrid biosynthesis of roseobacticides from algal and bacterial precursor molecules.  

PubMed

Roseobacticides regulate the symbiotic relationship between a marine bacterium (Phaeobacter inhibens) and a marine microalga (Emiliania huxleyi). This relationship can be mutualistic, when the algal host provides food for the bacteria and the bacteria produce growth hormones and antibiotics for the algae, or parasitic, when the algae senesce and release p-coumaric acid. The released p-coumaric acid causes the bacteria to synthesize roseobacticides, which are nM-?M toxins for the algae. We examined the biosynthesis of roseobacticides and report that all roseobacticide precursors play critical roles during the mutualist phase of the symbiosis. Roseobacticides are biosynthesized from the algal growth promoter, the major food molecule provided by the algal cells, and the algal senescence signal that initiates the mutualist-to-parasite switch. Thus, molecules that are beneficial during mutualism are diverted to the synthesis of toxins during parasitism. A plausible mechanism for assembling roseobacticides from these molecules is proposed. PMID:25295497

Seyedsayamdost, Mohammad R; Wang, Rurun; Kolter, Roberto; Clardy, Jon

2014-10-29

332

Biology and pathophysiology of the amyloid precursor protein  

PubMed Central

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

2011-01-01

333

Rhamnose Biosynthesis in Mycoplasmas Requires Precursor Glycans Larger than Monosaccharide  

PubMed Central

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

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

2013-01-01

334

Helium in silicon: Thermal-desorption investigation of bubble precursors  

NASA Astrophysics Data System (ADS)

Thermal desorption measurements are performed on (100)-oriented p-type Si wafers implanted with He ions at 20 keV. The doses have been selected in order to produce crystal damage avoiding the formation of detectable bubbles. The He effusion kinetics, studied both in isothermal and in constant heating rate conditions, exhibit effective activation energy heterogeneity indicating the presence of various kinds of traps, precursor of the bubbles. The energy distribution results peaked at about 1.1 eV with an exponential decay towards higher energies and a width of about 0.2 eV. A semiquantitative model, based on the present knowledge about the Si:He system, is proposed, that accounts for He filled nanoblisters formation through interstitial He clustering and precipitation. The observed energy heterogeneity is ascribed to variations of the He solution energy from these cavities due to He-He and He-wall interactions.

Corni, F.; Nobili, C.; Ottaviani, G.; Tonini, R.; Calzolari, G.; Cerofolini, G. F.; Queirolo, G.

1997-09-01

335

Amyloid Precursor Protein Is Trafficked and Secreted via Synaptic Vesicles  

PubMed Central

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

Riedel, Dietmar; Hua, Yunfeng; Huve, Jana; Wilhelm, Benjamin G.; Klingauf, Jurgen

2011-01-01

336

Synthesis of S-doped graphene by liquid precursor  

NASA Astrophysics Data System (ADS)

Doping is a common and effective approach to tailor semiconductor properties. Here, we demonstrate the growth of large-area sulfur (S)-doped graphene sheets on copper substrate via the chemical vapor deposition technique by using liquid organics (hexane in the presence of S) as the precursor. We found that S could be doped into graphene’s lattice and mainly formed linear nanodomains, which was proved by elemental analysis, high resolution transmission microscopy and Raman spectra. Measurements on S-doped graphene field-effect transistors (G-FETs) revealed that S-doped graphene exhibited lower conductivity and distinctive p-type semiconductor properties compared with those of pristine graphene. Our approach has produced a new member in the family of graphene based materials and is promising for producing graphene based devices for multiple applications.

Gao, Hui; Liu, Zheng; Song, Li; Guo, Wenhua; Gao, Wei; Ci, Lijie; Rao, Amrita; Quan, Weijin; Vajtai, Robert; Ajayan, Pulickel M.

2012-07-01

337

Seismic Precursors to Eruptions at Volcanoes in Extensional Stress Fields  

NASA Astrophysics Data System (ADS)

Quantitative analyses of seismic precursors to volcanic eruptions have focussed on volcanoes in compressional background stress fields at subduction zones. We here use the results from new laboratory rock-fracture experiments on alkali basalt from Mt Etna, in Sicily, to extend studies to volcanoes in extensional stress fields. Sequences of volcano-tectonic (VT) earthquakes before flank eruptions on Etna can develop over months-years, during most of which the cumulative number of events increases exponentially with time. To recreate field conditions, we used the fault jog method to generate an extensional stress. Two parallel slots, 2 mm wide, were cut at 30° to the axis in cylindrical samples, 40 mm across and 110 mm long. The perpendicular offset between slots was held at 10 mm, but the slot overlap was varied from 0 to 10 mm. Water saturated samples were deformed under triaxial stress at a strain rate of 10-5s-1, 60 MPa confining pressure and 20 MPa pore fluid pressure. Axial strain, volumetric strain and the number of acoustic emissions (AE) and their energy were measured as proxies for the accumulation of crack damage within each sample. Our first results show exponential increases with time in the cumulative number of AE events (analogues of VT events). The trends are consistent with a new theoretical model for which the exponential trend is characterised by the energy stored in the atomic structure at absolute temperatures and confining pressures above zero. The characteristic stored energy can be calculated knowing the rock composition, temperature and confining pressure. In our experiments, the exponential trends yield values for the characteristic stored energy of 28-36 MJ m-3. These compare well with the calculated values of 32 (+/- 20%) MJ m-3. The good agreement suggests that field precursors can be used as a basis for deterministic forecasts of eruptions.

Wall, R. J.; Kilburn, C. R. J.; Meredith, P. G.

2012-04-01

338

Structural comparison of nickel electrodes and precursor phases  

NASA Technical Reports Server (NTRS)

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.

Cornilsen, Bahne C.; Shan, Xiaoyin; Loyselle, Patricia

1989-01-01

339

[Thyroid hormones and their precursors I. Biochemical properties].  

PubMed

This paper and the following one (see the next issue of Acta Pharmaceutica Hungarica) survey the biological roles and the related site-specific physico-chemical parameters (basicity and lipophilicity) of the presently known thyroid hormones (thyroxine, liothyronine and reverse liothyronine) and their biological precursors (monoiodotyrosine and diiodotyrosine). Here the literature of the thyroid hormone biochemistry, biosynthesis, plasma- and membrane transport is summarized, focusing on the pH-dependent processes. Biosyntheses of the thyroid hormones take place by oxidative coupling of two iodotyrosine residues catalyzed by thyreoperoxidase in thyreoglobulin. The protonation state of the precursors, especially that of the phenolic OH is crucial for the biosynthesis, since anionic iodotyrosine residues can only be coupled in the thyroid hormone biosyntheses. In the blood more than 99% of the circulating thyroid hormone is bound to plasma proteins among which the thyroxine-binding globulin and transthyretin are crucial. The amphiphilic character of the hormones is assumed to be the reason why their membrane transport is an energy-dependent, transport-mediated process, in which the organic anion transporter family, mainly OATP1C1, and the amino acid transporters, such as MCT8 play important roles. Liothyronine is the biologically active hormone; it binds the thyroid hormone receptor, a type of nuclear receptor. There are two major thyroid hormone receptor (TR) isoforms, alfa (TRalpha) and beta (TRbeta). The activation of the TRalpha is associated with modifications in cardiac behavior, while activation of the TRbeta is associated with increasing metabolic rates, resulting in weight loss and reduction of blood plasma lipid levels. The affinity of the thyroid hormones for different proteins depends on the ionization state of the ligands. The site-specific physico-chemical characterization of the thyroid hormones is of fundamental importance to understand their (patho)physiological behavior and also, to influence their therapeutic properties at the molecular level. PMID:23926648

Tóth, Gergo; Noszál, Béla

2013-01-01

340

The Fe/Mn constraint on precursors of basaltic achondrites  

NASA Technical Reports Server (NTRS)

Most achondritic meteorites have Fe/Mn ratios that are lower than those of carbonaceous chondrites and of course are lower than the solar system abundance ratio of these elements. Models of the origin of achondritic assemblages must, therefore, account for these ratios. Fe/Mn ratios are suggested to be distinctive for samples from each achondrite parent body and for the Earth and Moon, but the correspondence between the Fe/Mn systematics of achondrites and chondritic precursors is unclear. Most models of achondrite genesis involve magmatic differentiation of chondritic precursors. The Fe/Mn difference between achondrites and chondrites is particularly significant since Fe and Mn are geochemically similar elements with similar partitioning behavior in familiar magmatic systems and are generally coupled during crystal-liquid fractionation. In contrast, however, Mn is more volatile than Fe in a nebular setting. Variation of Fe/Mn ratios based on the relative volatility of these elements in the early nebula provides a constraint for models by which the basaltic achondrites (with Fe/Mn ratios approximately = 25-50) are derived from mixtures of nebular components that were enriched in volatile components such as Mn. However, such volatile enriched components have not been identified in chondrites. When the abundance in achondrites of elements of similar volatility is examined, anomalies appear. For example, Na is massively depleted in basaltic achondrites when compared to Mn. These anomalies might be explained using current models but the alternative hypothesis, that Fe/Mn ratio is controlled not by nebular volatility constraints, but by planetary differentiation should be explored.

Delaney, Jeremy S.; Boesenberg, Joseph S.

1993-01-01

341

Enantiomeric Excesses of Acid Labile Amino Acid Precursors of the Murchison Meteorite  

NASA Technical Reports Server (NTRS)

Amino acids present in carbonaceous chondrite are extracted in water in part as free compounds and in approximately equal part as acid labile precursors. On the assumption that they would be free of contamination, the precursors of two Murchison amino acids that have terrestrial occurrence, alanine and glutamic acid, have been targeted for analysis of their enantiomeric ratios. Pyroglutamic acid, the precursor of glutamic acid, was found with an L-enantiomeric excess comparable to that of the free acid, while alanine's precursor, N-acetyl alanine, appears approximately racemic. Also alpha-imino propioacetic acid, a proposed end product of alanine synthesis in the meteorite, was analyzed and found racemic.

Pizzarello, Sandra

1998-01-01

342

Novel applications of ceramic precursors -- TiN coating on alumina and functionally gradient materials  

SciTech Connect

There are very few demonstrated applications of ceramic precursor technology. Here, the authors describe two new applications of known ceramic precursors, thin film deposition and the fabrication of functionally gradient materials (FGM). To demonstrate the thin film deposition, the authors prepared titanium nitride film on an alumina substrate using (CH{sub 3}){sub 3}SiNHTiCl{sub 3} precursor by a single dipcoat-fire cycle. The fabrication of copper and aluminum based FGMs was demonstrated using Nicalon{reg_sign} fiber polycarbosilane and poly(methylsilane) precursors as binders and in situ sources of ceramics.

Seyferth, D. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Chemistry; Narula, C.K. [Ford Motor Co., Dearborn, MI (United States). Dept. of Chemistry; Czubarow, P. [Raychem Corp., Menlo Park, CA (United States)

1996-12-31

343

Formation of perfluorinated surfactants from precursors by indigenous microorganisms in groundwater.  

PubMed

The formation of perfluorinated surfactants (PFSs) from their precursors in waters is of concern. In this study, the formation of PFSs through biodegradation of precursors was measured in incubation tests. Indigenous microorganisms in groundwater were able to biodegrade perfluorooctane sulfonamide (FOSA) to yield perfluorooctane sulfonate (PFOS). The addition of nutrients and soil promoted the formation. A 42-d incubation test using sources of groundwater recharge showed that PFOS, perfluorooctanoate, and perfluorononanoate were significantly and remarkably (?1.5×) formed from precursors in street runoff through biodegradation, but not in rainwater or wastewater effluent. Significant formation of PFSs from precursors in street runoff was observed. PMID:23746363

Murakami, Michio; Nishikoori, Hiroshi; Sakai, Hiroshi; Oguma, Kumiko; Takada, Hideshige; Takizawa, Satoshi

2013-09-01

344

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

NASA Astrophysics Data System (ADS)

We investigate the observability, by direct and indirect means, of a shock precursor arising from magnetic field amplification by cosmic rays. We estimate the depth of such a precursor under conditions of nonresonant amplification, which can provide magnetic field strengths comparable to those inferred for supernova remnants. Magnetic field generation occurs as the streaming cosmic rays induce a plasma return current, and it may be quenched by either nonresonant or resonant channels. In the case of nonresonant saturation, the cosmic rays become magnetized and amplification saturates at higher magnetic fields. The precursor can extend out to 1017-1018 cm and is potentially detectable. If resonant saturation occurs, the cosmic rays are scattered by turbulence and the precursor length will likely be much smaller. The dependence of precursor length on shock velocity has implications for electron heating. In the case of resonant saturation, this dependence is similar to that in the more familiar resonantly generated shock precursor, which when expressed in terms of the cosmic-ray diffusion coefficient kappav and shock velocity vs is kappav/vs . In the nonresonantly saturated case, the precursor length declines less quickly with increasing vs . Where precursor length proportional to 1/vs gives constant electron heating, this increased precursor length could be expected to lead to higher electron temperatures for nonresonant amplification. This should be expected at faster supernova remnant shocks than studied by previous works. Existing results and new data analysis of SN 1006 and Cas A suggest some observational support for this idea.

Laming, J. Martin; Hwang, Una; Ghavamian, Parviz; Rakowski, Cara

2014-07-01

345

The synthesis of ?-alkoxy and ?-aminostannanes as precursors to Novel Chromium Fischer Carbenes.  

E-print Network

??The present study involves the use of main group organometallics: organostannanes and organolithiums as precursors to chromium Fischer carbene complexes. Fischer carbenes are well stabilized… (more)

Meyer, Annalene

2012-01-01

346

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

Department of Emergency Medicine, University of California, Irvine Medical Center, Orange, CA bDepartment of Chemistry- gency Medicine Research Forum, Santa Ana, CA, March 28, 2008; and Society for Academic Emergency for this study. Corresponding Author: Jeffrey R. Suchard, MD, UCIMC, Dept of Emergency Medicine, 101 The City

Nizkorodov, Sergey

347

Spray dried glyceryl monooleate-magnesium trisilicate dry powder as cubic phase precursor.  

PubMed

Glyceryl monooleate (GMO) is a polar amphiphilic lipid, which forms different sequential lyotropic liquid crystals upon hydration. GMO has been utilized for various delivery systems and routes of administrations. Owing to sticky and waxy nature of GMO, preparation of oral solid dosage form utilizing GMO is still a challenge for pharmaceutical researchers. Therefore, the objective of the present work was to fabricate dry powder precursors using GMO, which upon hydration in situ forms cubic phase and can be wisely used for fabrication of oral solid dosage forms. In addition to this, dry powder precursor was evaluated for drug loading, in vitro release behavior and in vivo performance of model drug diclofenac sodium (DiNa). The dry powder precursor was obtained by spray-drying GMO with DiNa using magnesium trisilicate (MTS) as adsorbent. The percent drug entrapment of various batches of powder precursor was in the range of 84-93% indicating high content uniformity. SEM and image analysis showed that as the amount of MTS in powder precursor was increased, the particle size decreased. Furthermore, the viscosity of powder precursor was function of amount of MTS. The rate of water uptake of powder precursor was higher due to uniform layer of GMO on the MTS surface, which led to faster transformation of lamellar phase into cubic phase. The polarizing light microscopy confirmed that cubic phase was formed upon hydration of powder precursor. The drug released from powder precursor was initially governed by the cubic phase formed and in later stage it depends upon dynamic swelling behavior of hexagonally packed cylindrical aggregates. The drug loaded powder precursor was found to have more effective and prolonged anti-inflammatory and analgesic activity as compared to pure drug. Thus the dry powder precursor of cubic phase was prepared in which drug release was entirely governed by the mesophases formed. PMID:16846704

Shah, Manish H; Biradar, Shailesh V; Paradkar, Anant R

2006-10-12

348

NASA Accident Precursor Analysis Handbook, Version 1.0  

NASA Technical Reports Server (NTRS)

Catastrophic accidents are usually preceded by precursory events that, although observable, are not recognized as harbingers of a tragedy until after the fact. In the nuclear industry, the Three Mile Island accident was preceded by at least two events portending the potential for severe consequences from an underappreciated causal mechanism. Anomalies whose failure mechanisms were integral to the losses of Space Transportation Systems (STS) Challenger and Columbia had been occurring within the STS fleet prior to those accidents. Both the Rogers Commission Report and the Columbia Accident Investigation Board report found that processes in place at the time did not respond to the prior anomalies in a way that shed light on their true risk implications. This includes the concern that, in the words of the NASA Aerospace Safety Advisory Panel (ASAP), "no process addresses the need to update a hazard analysis when anomalies occur" At a broader level, the ASAP noted in 2007 that NASA "could better gauge the likelihood of losses by developing leading indicators, rather than continue to depend on lagging indicators". These observations suggest a need to revalidate prior assumptions and conclusions of existing safety (and reliability) analyses, as well as to consider the potential for previously unrecognized accident scenarios, when unexpected or otherwise undesired behaviors of the system are observed. This need is also discussed in NASA's system safety handbook, which advocates a view of safety assurance as driving a program to take steps that are necessary to establish and maintain a valid and credible argument for the safety of its missions. It is the premise of this handbook that making cases for safety more experience-based allows NASA to be better informed about the safety performance of its systems, and will ultimately help it to manage safety in a more effective manner. The APA process described in this handbook provides a systematic means of analyzing candidate accident precursors by evaluating anomaly occurrences for their system safety implications and, through both analytical and deliberative methods used to project to other circumstances, identifying those that portend more serious consequences to come if effective corrective action is not taken. APA builds upon existing safety analysis processes currently in practice within NASA, leveraging their results to provide an improved understanding of overall system risk. As such, APA represents an important dimension of safety evaluation; as operational experience is acquired, precursor information is generated such that it can be fed back into system safety analyses to risk-inform safety improvements. Importantly, APA utilizes anomaly data to predict risk whereas standard reliability and PRA approaches utilize failure data which often is limited and rare.

Groen, Frank; Everett, Chris; Hall, Anthony; Insley, Scott

2011-01-01

349

From iron(III) precursor to magnetite and vice versa  

SciTech Connect

The syntheses of nanosize magnetite particles by wet-chemical oxidation of Fe{sup 2+} have been extensively investigated. In the present investigation the nanosize magnetite particles were synthesised without using the Fe(II) precursor. This was achieved by {gamma}-irradiation of water-in-oil microemulsion containing only the Fe(III) precursor. The corresponding phase transformations were monitored. Microemulsions (pH {approx} 12.5) were {gamma}-irradiated at a relatively high dose rate of {approx}22 kGy/h. Upon 1 h of {gamma}-irradiation the XRD pattern of the precipitate showed goethite and unidentified low-intensity peaks. Upon 6 h of {gamma}-irradiation, reductive conditions were achieved and substoichiometric magnetite ({approx}Fe{sub 2.71}O{sub 4}) particles with insignificant amount of goethite particles found in the precipitate. Hydrated electrons (e{sub aq}{sup -}), organic radicals and hydrogen gas as radiolytic products were responsible for the reductive dissolution of iron oxide in the microemulsion and the reduction Fe{sup 3+} {yields} Fe{sup 2+}. Upon 18 h of {gamma}-irradiation the precipitate exhibited dual behaviour, it was a more oxidised product than the precipitate obtained after 6 h of {gamma}-irradiation, but it contained magnetite particles in a more reduced form ({approx}Fe{sub 2.93}O{sub 4}). It was presumed that the reduction and oxidation processes existed as concurrent competitive processes in the microemulsion. After 18 h of {gamma}-irradiation the pH of the medium shifted from the alkaline to the acidic range. The high dose rate of {approx}22 kGy/h was directly responsible for this shift to the acidic range. At a slightly acidic pH a further reduction of Fe{sup 3+} {yields} Fe{sup 2+} resulted in the formation of more stoichiometric magnetite particles, whereas the oxidation conditions in the acidic medium permitted the oxidation Fe{sup 2+} {yields} Fe{sup 3+}. The Fe{sup 3+} was much less soluble in the acidic medium and it hydrolysed and recrystallised as goethite. The {gamma}-irradiation of the microemulsion for 25 h at a lower dose rate of 16 kGy/h produced pure substoichiometric nanosize magnetite particles of about 25 nm in size and with the stoichiometry of Fe{sub 2.83}O{sub 4}.

Gotic, M., E-mail: gotic@irb.hr [Division of Materials Chemistry, Ruder Boskovic Institute, P.O. Box 180, HR-10002 Zagreb (Croatia); Jurkin, T.; Music, S. [Division of Materials Chemistry, Ruder Boskovic Institute, P.O. Box 180, HR-10002 Zagreb (Croatia)

2009-10-15

350

Synthesis of functional aromatic multisulfonyl chlorides and their masked precursors.  

PubMed

The synthesis of functional aromatic bis(sulfonyl chlorides) containing an acetophenone and two sulfonyl chloride groups, i.e., 3,5-bis[4-(chlorosulfonyl)phenyl]-1-acetophenone (16), 3,5-bis(chlorosulfonyl)-1-acetophenone (17), and 3,5-bis(4-(chlorosulfonyl)phenyloxy)-1-acetophenone (18) via a sequence of reactions, involving in the last step the quantitative oxidative chlorination of S-(aryl)- N,N'-diethylthiocarbamate, alkyl- or benzyl thiophenyl groups as masked nonreactive precursors to sulfonyl chlorides is described. A related sequence of reactions was used for the synthesis of the aromatic trisulfonyl chloride 1,1,1-tris(4-chlorosulfonylphenyl)ethane (24). 4-(Chlorosulfonyl)phenoxyacetic acid, 2,2-bis[[[4-(chlorosulfonyl)phenoxyacetyl]oxy]methyl]-1,3-propanediyl ester (27), 5,11,17,23-tetrakis(chlorosulfonyl)-25,26,27,28-tetrakis(ethoxycarbonylmethoxy)calix[4]arene (38), 5,11,17,23,29,35-hexakis(chlorosulfonyl)-37,38,39,40,41,42-hexakis(ethoxycarbonylmethoxy)calix[6]arene (39), 5,11,17,23,29,35,41,47-octakis(chlorosulfonyl)-49,50,51,52,53,54,55,56-octakis(ethoxycarbonylmethoxy)calix[8]arene (40), 5,11,17,23-tetrakis(tert-butyl)-25,26,27,28-tetrakis(chlorosulfonyl phenoxyacetoxy)calix[4]arene (44), 5,11,17,23,29,35-hexakis(tert-butyl)-37,38,39,40,41,42-hexakis(chlorosulfonylphenoxyacetoxy)calix[6]arene (45), and 5,11,17,23,29,35,41,47-octakis(tert-butyl)-49,40,51,52,53,54,55,56-octakis(chlorosulfonylphenoxyacetoxy)calix[8]arene (46) were synthesized by two different multistep reaction procedures, the last step of both methods consisting of the chlorosulfonation of compounds containing suitable activated aromatic positions. 2,4,6-Tris(chlorosulfonyl)aniline (47) was obtained by the chlorosulfonation of aniline. The conformation of two series of multisulfonyl chlorides i.e., 38, 39, 40 and 44, 45, 46, was investigated by (1)H NMR spectroscopy. The masked nonreactive precursor states of the functional aromatic multisulfonyl chlorides and the aromatic multisulfonyl chlorides reported here represent the main starting building blocks required in a new synthetic strategy elaborated for the preparation of dendritic and other complex organic molecules. PMID:11300908

Percec, V; Bera, T K; De, B B; Sanai, Y; Smith, J; Holerca, M N; Barboiu, B; Grubbs, R B; Fréchet, J M

2001-03-23

351

Isolation and Characterization of Tumorigenic, Stemlike Neural Precursors from Human Glioblastoma  

Microsoft Academic Search

Transformed stem cells have been isolated from some human cancers. We report that, unlike other brain cancers, the lethal glioblastoma mul- tiforme contains neural precursors endowed with all of the critical fea- tures expected from neural stem cells. Similar, yet not identical, to their normal neural stem cell counterpart, these precursors emerge as unipo- tent (astroglial) in vivo and multipotent

Rossella Galli; Elena Binda; Ugo Orfanelli; Barbara Cipelletti; Angela Gritti; Simona De Vitis; Roberta Fiocco; Chiara Foroni; Francesco Dimeco; Angelo Vescovi

2004-01-01

352

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

Microsoft Academic Search

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

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

2002-01-01

353

More on a statistical analysis of log-periodic precursors to financial crashes  

Microsoft Academic Search

We respond to Sornette and Johansen's criticisms of our findings regarding log-periodic precursors to financial crashes. Included in this paper are discussions of the Sornette-Johansen theoretical paradigm, traditional methods of identifying log-periodic precursors, the behaviour of the first differences of a log-periodic price series and the distribution of drawdowns for a securities price.

James A. Feigenbaum

2001-01-01

354

Growth of magnesium oxide thin lms using single molecular precursors by metalorganic chemical vapor deposition  

E-print Network

Growth of magnesium oxide thin ®lms using single molecular precursors by metal±organic chemical precursors; Silicon; Sapphire 1. Introduction Magnesium oxide (MgO) thin ®lms have attracted much attention MgO ®lms on Si(100) above 6508C by thermal CVD. Murayama and Shionoya [12] used magnesium 2

Boo, Jin-Hyo

355

Testing the Predictors of Boredom at School: Development and Validation of the Precursors to Boredom Scales  

ERIC Educational Resources Information Center

Background: Boredom has been found to be an important emotion for students' learning processes and achievement outcomes; however, the precursors of this emotion remain largely unexplored. Aim: In the current study, scales assessing the precursors to boredom in academic achievement settings were developed and tested. Sample: Participants were 1,380…

Daschmann, Elena C.; Goetz, Thomas; Stupnisky, Robert H.

2011-01-01

356

From high molecular weight precursor polyrotaxanes to supramolecular sliding networks. The ‘sliding gels’  

Microsoft Academic Search

This paper presents the synthesis and characterization of an original class of supramolecular networks, the ‘sliding’ gels. In this new class of network materials the crosslink points are not fixed but sliding. The molecular structure is based on intermolecularly crosslinked ?-cyclodextrins\\/poly(ethylene-glycol) precursor polyrotaxanes. A synthetic method was developed to obtain various high molecular weight precursor polyrotaxanes with various amounts of

Guillaume Fleury; Guy Schlatter; Cyril Brochon; Georges Hadziioannou

2005-01-01

357

Vaporization of a mixed precursors in chemical vapor deposition for YBCO films  

NASA Technical Reports Server (NTRS)

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.

Zhou, Gang; Meng, Guangyao; Schneider, Roger L.; Sarma, Bimal K.; Levy, Moises

1995-01-01

358

N,S-Dimethyldithiocarbamyl oxalates as precursors for determining kinetic parameters for oxyacyl radicals.  

PubMed

N,S-Dimethyldithiocarbamyl oxalates (e.g., ) are novel, readily prepared precursors to alkyloxyacyl radicals that are more suitable for kinetic studies than existing precursors; has allowed the determination of accurate rate data for the cyclization of the butenyloxyacyl radical 5 (kc = 1.2 × 10(7) s(-1) at 21 °C). PMID:25171586

Kyne, Sara H; Schiesser, Carl H

2014-09-16

359

Controlling the synthesis of TaC nanopowders by injecting liquid precursor into RF induction plasma  

Microsoft Academic Search

Thermal plasma processing has been used to synthesize nano-size powders through the condensation of reactant species from a vapor phase. Further development of this synthesis method will require the careful selection of an appropriate precursor and precise control of products species and their particle sizes. Direct introduction of liquid mist into thermal plasma gives us a wider choice of precursors

Takamasa Ishigaki; Seung-Min Oh; Ji-Guang Li; Dong-Wha Park

2005-01-01

360

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

Microsoft Academic Search

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

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

2001-01-01

361

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

E-print Network

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

Bongarzone, Ernesto R.

362

Lead sulfate precursor to positive active material in lead\\/acid batteries  

Microsoft Academic Search

Lead\\/acid batteries occupy a very important position in the fields of secondary batteries for the higher performance and cost ratio. But when lead powder is used as a precursor to the active material, the production time is very long and the environmental pollution is very serious. Thus many people are seeking new material instead of lead powder. A new precursor

Zhigang Yan; Xinguo Hu

2003-01-01

363

Development of neuronal precursor cells and functional postmitotic neurons from embryonic stem cells in vitro  

Microsoft Academic Search

To understand the mechanism of the sequential restriction of multipotency of stem cells during development, we have established culture conditions that allow the differentiation of neuroepithelial precursor cells from embryonic stem (ES) cells. A highly enriched population of neuroepithelial precursor cells derived from ES cells proliferates in the presence of basic fibroblast growth factor (bFGF). These cells differentiate into both

Shigeo Okabe; Karin Forsberg-Nilsson; A. Cyril Spiro; Menahem Segal; Ronald D. G. McKay

1996-01-01

364

Identication of a novel alternative splicing isoform of human amyloid precursor protein gene, APP639  

E-print Network

Identi®cation of a novel alternative splicing isoform of human amyloid precursor protein gene, APP, Meibergdreef 33, 1105 AZ Amsterdam ZO, the Netherlands Keywords: alternative splicing, Alzheimer's disease, APP derived from a large amyloid precursor protein (APP). To date, several alternatively spliced human APP

Tian, Weidong

365

Isolation of neural precursor cells from Alzheimer's disease and aged control postmortem brain.  

PubMed

Recent studies demonstrate that isolated neural precursor cells are capable of generating neurons, astrocytes, and oligodendrocytes from neurogenic regions of adult brain. Because these studies use surgically resected or fresh postmortem specimens from young subjects, it is not clear whether neural precursor cells remain in the brain of normal aged subjects or subjects with Alzheimer's disease (AD). The purpose of this study was to determine if viable precursor cells remain in aged control and AD brain. AD subjects have significantly fewer viable precursor cells in the hippocampus compared with age-matched normal control subjects. Musashi-1 and Ki-67-positive precursor cells from AD self renew, but reach senescence earlier than cells isolated from normal aged control subjects. Precursor cells from AD and aged normal control specimens can differentiate into tubulin- and Tuj-1-positive neurons and GFAP-positive astrocytes. This study demonstrates that viable precursor cells remain in AD and aged normal control brain specimens and can be induced to differentiate. These results raise the possibility of stimulation of inherent precursor cells of aged individuals or AD patients to replace neurons lost in aging and/or neurodegeneration. PMID:15979211

Lovell, Mark A; Geiger, Hartmut; Van Zant, Gary E; Lynn, Bert C; Markesbery, William R

2006-07-01

366

Estimating the Precursor Frequency of Naive Antigen-specific CD8 T Cells  

Microsoft Academic Search

The constraint of fitting a diverse repertoire of antigen specificities in a limited total population of lymphocytes results in the frequency of naive cells specific for any given antigen (defined as the precursor frequency) being below the limit of detection by direct measurement. We have estimated this precursor frequency by titrating a known quantity of antigen-specific cells into naive recipients.

Joseph N. Blattman; Rustom Antia; David J. D. Sourdive; Xiaochi Wang; Susan M. Kaech; Kaja Murali-Krishna; John D. Altman; Rafi Ahmed

2002-01-01

367

Synthesis of nanosized tungsten carbide from phenol formaldehyde resin coated precursors  

Microsoft Academic Search

Nanosized tungsten carbide was synthesized from phenol formaldehyde resin (PF) coated tungsten precursors. The process has three steps in which nanosized tungsten particles were first coated with PF, then the precursors were carburized at 950°C, and finally the carburized powders were treated in flowing wet hydrogen atmosphere at 940°C to remove the uncombined carbon. The obtained powders were characterized using

Ji LUO; Zhimeng GUO; Yuxi GAO; Tao LIN

2008-01-01

368

Exploring Essential Attributes For Detecting MicroRNA Precursors From Background  

E-print Network

Exploring Essential Attributes For Detecting MicroRNA Precursors From Background Sequences Yun. MicroRNAs (miRNAs) have been shown to play important roles in post-transcriptional gene regulation. The hairpin structure is a key characteristic of the microRNAs precursors (pre-miRNAs). How to encode

Wong, Limsoon

369

LIPOPOLYSACCHARIDE MEDIATED REGULATION OF NEUROENDOCRINE ASSOCIATED PROPROTEIN CONVERTASES AND NEUROPEPTIDE PRECURSOR  

E-print Network

LIPOPOLYSACCHARIDE MEDIATED REGULATION OF NEUROENDOCRINE ASSOCIATED PROPROTEIN CONVERTASES AND NEUROPEPTIDE PRECURSOR PROCESSING IN THE RAT SPLEEN. Guillaume Lansac1 , Weijia Dong2 , Claire M. Dubois3, the family of proprotein convertases cleave inactive precursors at paired basic residues to generate a myriad

370

MatureBayes: A Probabilistic Algorithm for Identifying the Mature miRNA within Novel Precursors  

E-print Network

MatureBayes: A Probabilistic Algorithm for Identifying the Mature miRNA within Novel Precursors-transcriptional regulation of thousands of genes across numerous species. While several computational methods are currently(s) of miRNA precursors. Methodology/Principal Findings: Here, we present a computational tool

Tsakalides, Panagiotis

371

Proximal visceral endoderm and extraembryonic ectoderm regulate the formation of primordial germ cell precursors  

E-print Network

:gfp transgenic mouse lines were used to distinguish between PGC precursors and specified PGC, respectively. We observed that the VE regulates formation of an appropriate number of PGC precursors between E6.25–E7.25, but it is not essential...

Chuva de Sousa Lopes, Susana M; Hayashi, Katsuhiko; Surani, M Azim

2007-12-20

372

Development/Plasticity/Repair Transplantation of Neuronal and Glial Restricted Precursors  

E-print Network

Development/Plasticity/Repair Transplantation of Neuronal and Glial Restricted Precursors 19129 Transplanting neuronal and glial restricted precursors (NRP/GRP) into a midthoracic injury 9 d after spinal injury and descending noradrenergic path- ways contribute to regulation of bladder control

Fischer, Itzhak

373

In vitro-Generated Neural Precursors Participate in Mammalian Brain Development  

Microsoft Academic Search

During embryogenesis, pluripotent stem cells segregate into daughter lineages of progressively restricted developmental potential. In vitro, this process has been mimicked by the controlled differentiation of embryonic stem cells into neural precursors. To explore the developmental potential of these cell-culture-derived precursors in vivo, we have implanted them into the ventricles of embryonic rats. The transplanted cells formed intraventricular neuroepithelial structures

Oliver Brustle; A. Cyril Spiro; Khalad Karram; Khalid Choudhary; Shigeo Okabe; Ronald D. G. McKay

1997-01-01

374

Restricted growth potential of rat neural precursors as compared to mouse  

Microsoft Academic Search

Epidermal growth factor (EGF) responsive precursors isolated from the developing mouse striatum could be continually expanded in culture as free-floating spheres of cells for over 50 days. Under identical conditions, EGF-responsive precursors from the developing rat striatum could only be expanded for between 21 and 28 days, after which crisis ensued and there was a reduction in cell number at

Clive N Svendsen; Jeremy Skepper; Anne E Rosser; Melanie G ter Borg; Pam Tyres; Tim Ryken

1997-01-01

375

Chloroplast SRP54 Interacts with a Specific Subset of Thylakoid Precursor Proteins*  

E-print Network

Chloroplast SRP54 Interacts with a Specific Subset of Thylakoid Precursor Proteins* (Received-functional targeting signals. Using a range of authentic thylakoid precursor proteins we found that 54CP discriminates of the thylakoid-targeting signal and, in the case of light-harvesting chlorophyll a/b-binding protein

376

Thymotaxin: A Thymic Epithelial Peptide Chemotactic for T-Cell Precursors  

Microsoft Academic Search

The embryonic thymus is seeded by invading hemopoietic precursor cells that differentiate intrathymically into T lymphocytes. We have recently reported that avian thymic epithelial cells secrete chemotactic peptides, which provoke oriented migration of hemopoietic precursor cells in vitro. The established rat thymic epithelial cell line IT-45 R1 produced a polypeptide that resolves as a single band in the region of

Beat A. Imhof; Marie-Ange Deugnier; Jeanne-Marie Girault; Serge Champion; Chantal Damais; Tsunetoshi Itoh; Jean Paul Thiery

1988-01-01

377

Production of activated carbon from a new precursor molasses by activation with sulphuric acid  

Microsoft Academic Search

Activated carbon has been prepared from molasses, a natural precursor of vegetable origin resulting from the sugar industry in Morocco. The preparation of the activated carbon from the molasses has been carried out by impregnation of the precursor with sulphuric acid, followed by carbonisation at varying conditions (temperature and gas coverage) in order to optimize preparation parameters. The influence of

K. Legrouri; E. Khouya; M. Ezzine; H. Hannache; R. Denoyel; R. Pallier; R. Naslain

2005-01-01

378

Real-time Detection of Precursors to Epileptic Seizures: Non-Linear Analysis of System Dynamics  

PubMed Central

We propose a novel approach for detecting precursors to epileptic seizures in intracranial electroencephalograms (iEEG), which is based on the analysis of system dynamics. In the proposed scheme, the largest Lyapunov exponent of the discrete wavelet packet transform (DWPT) of the segmented EEG signals is considered as the discriminating features. Such features are processed by a support vector machine (SVM) classifier to identify whether the corresponding segment of the EEG signal contains a precursor to an epileptic seizure. When consecutive EEG segments contain such precursors, a decision is made that a precursor is in fact detected. The proposed scheme is applied to the Freiburg dataset, and the results show that seizure precursors are detected in a time frame that unlike other existing schemes is very much convenient to patients, with sensitivity of 100% and negligible false positive detection rates. PMID:24761374

Nesaei, Sahar; Sharafat, Ahmad R.

2014-01-01

379

Snail Coordinately Regulates Downstream Pathways to Control Multiple Aspects of Mammalian Neural Precursor Development  

PubMed Central

The Snail transcription factor plays a key role in regulating diverse developmental processes but is not thought to play a role in mammalian neural precursors. Here, we have examined radial glial precursor cells of the embryonic murine cortex and demonstrate that Snail regulates their survival, self-renewal, and differentiation into intermediate progenitors and neurons via two distinct and separable target pathways. First, Snail promotes cell survival by antagonizing a p53-dependent death pathway because coincident p53 knockdown rescues survival deficits caused by Snail knockdown. Second, we show that the cell cycle phosphatase Cdc25b is regulated by Snail in radial precursors and that Cdc25b coexpression is sufficient to rescue the decreased radial precursor proliferation and differentiation observed upon Snail knockdown. Thus, Snail acts via p53 and Cdc25b to coordinately regulate multiple aspects of mammalian embryonic neural precursor biology. PMID:24719096

Zander, Mark A.; Burns, Sarah E.; Yang, Guang; Kaplan, David R.

2014-01-01

380

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

SciTech Connect

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.

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

1998-04-01

381

Risk and return: evaluating Reverse Tracing of Precursors earthquake predictions  

NASA Astrophysics Data System (ADS)

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.

Zechar, J. Douglas; Zhuang, Jiancang

2010-09-01

382

Low-temperature synthesis of binary cuprates from hydroxide precursor  

NASA Astrophysics Data System (ADS)

Binary cuprates of Sr2CuO3+? and SrCuO2 have been synthesized at low temperatures below 500 °C under various values of partial oxygen-pressureP_{O_2 } by thermal decomposition of hydroxide precursors, Sr2Cu(OH)6 and SrCu(OH)4, respectively. The tetragonal Sr2CuO3+? (? ˜ 0.3) is obtained by the heat-treatment at 400 ° C andP_{O_2 } ? 0.2 atm. The value of ? appears to be independent ofP_{O_2 } and unchangeable. On the other hand, the orthorhombic Sr2CuO3+? (? ˜ 0) is obtained by the heat-treatment at 400 °C in flowing gas of N2. For 0

Kato, Masatsune; Miyajima, Toyoo; Nagai, Ichiro; Koike, Yoji

1996-12-01

383

Alzheimer beta A4-amyloid protein precursor in immunocompetent cells.  

PubMed

The mechanism of proteolytic breakdown of the beta A4-amyloid protein precursor (APP) has attracted much attention because of its relevance for Alzheimer's disease. Apart from the pathological role of APP in the amyloidogenesis, many efforts have been made to identify the functional significance of this widely expressed protein in various biological processes. Employing biochemical techniques, we demonstrate that APP is involved in the initiation of the immune response. Upon stimulation, it is expressed by the major functional types of T-lymphocytes, i.e. CD4+ and CD8+ cells. As was demonstrated for the CD4+ lymphoid cell line H9, APP is predominantly secreted. The remaining COOH-terminal fragments generated upon secretion were highly unstable. Of the APP produced by immunocompetent cells, considerable amounts were shown to be leukocyte-derived APP (L-APP). In addition, we were able to identify the KPI-containing L-APP isoform, L-APP733, as the major expressed L-APP isoform in immunocompetent cells, including rat microglial cells and astrocytes. The L-APP expression pattern of these cells showed high similarity. These findings seem to be indicative of an important function of APP within the immune system. Therefore, APP may be involved in various immunopathogenic conditions of the periphery and in the central nervous system. PMID:1429732

Mönning, U; König, G; Banati, R B; Mechler, H; Czech, C; Gehrmann, J; Schreiter-Gasser, U; Masters, C L; Beyreuther, K

1992-11-25

384

Interaction of glycine with common atmospheric nucleation precursors.  

PubMed

The interaction between the simplest amino acid glycine in three different protonation states and common atmospheric nucleation precursors (H2O, NH3, and H2SO4) has been investigated using computational methods. Each nucleation step has been thoroughly sampled, and statistical Gibbs free energies of formation have been calculated using M06-2X/6-311++G(3df,3pd). From the stepwise ?G values, the stabilities of the molecular clusters have been evaluated. Glycine in all three protonation states is found to have a favorable interaction with sulfuric acid with a higher cluster stabilizing effect than ammonia. The deprotonated glycine molecule is found to yield the highest stabilizing effect on the sulfuric acid clusters through the interaction of both the amino and carboxylic moieties, while the protonated glycine molecule is found to have a high stabilizing effect on the addition of water and ammonia. Furthermore, we find that a single sulfuric acid molecule is capable of stabilizing the glycine zwitterion. Sulfuric acid is found to be able to catalyze the spontaneous formation of the zwitterion and subsequently stabilize the formed ion. The formation of the glycine zwitterion occurs with a low Gibbs free energy barrier of 2.10 kcal/mol, indicating that this formation could occur rapidly in the atmosphere. PMID:24191651

Elm, Jonas; Fard, Mehrnoush; Bilde, Merete; Mikkelsen, Kurt V

2013-12-01

385

Alkynylisocyanide gold mesogens as precursors of gold nanoparticles.  

PubMed

Gold nanoparticles (Au NPs) have been synthesized using simple thermolysis, whether from the mesophase or from toluene solutions, of mesogenic alkynyl-isocyanide gold complexes [Au(C?C-C(6)H(4)-C(m)H(2m+1))(C?N-C(6)H(4)-O-C(n)H(2n+1))]. The thermal decomposition from the mesophase is much slower than from solution and produces a more heterogeneous size distribution of the nanoparticles. Working in toluene solution, the size of nanoparticles can be modulated from ~2 to ~20 nm by tuning the chain lengths of the ligands present in the precursor. Different experimental conditions have been analyzed to reveal the processes governing the formation of the gold nanoparticles. Experiments on the effect of adding ligands or bubbling oxygen support that the thermal decomposition is a bimolecular process that starts by decoordination of the isocyanide ligand, producing an oxidative coupling of the akynyl group to [R-C?C-C?C-R] and reduction of gold(I) to gold(0) as nanoparticles. The nanoparticles obtained behave as a catalyst in the oxidation of isocyanide (CNR) to isocyanate (OCNR), which in turn cooperates to catalyze the decomposition. PMID:21815613

Chico, Rubén; Castillejos, Eva; Serp, Philippe; Coco, Silverio; Espinet, Pablo

2011-09-01

386

Nucleobindins: bioactive precursor proteins encoding putative endocrine factors?  

PubMed

The nucleobindins, nucleobindin 1 (NUCB1) and nucleobindin 2 (NUCB2), are homologous multidomain calcium and DNA binding proteins. NUCB1 is a well-characterized Golgi protein found within the rat pituitary, liver and kidney with functions related to immunity, calcium homeostasis and G protein signaling. NUCB2 is found both in the hypothalamus and brain stem centers, as well as peripherally in the digestive tract. Renewed interest in the nucleobindins has been sparked by the recent discovery of nesfatin-1, an endocrine factor post-translationally processed from the N-terminal of NUCB2. Nesfatin-1 has quickly established itself as a novel regulator of appetite, insulin secretion, energy homeostasis and reproduction with important consequences to the etiology of metabolic diseases including diabetes and obesity. The discovery of nesfatin-1 and it endocrine functions attracted more attention to the nucleobindins that are already known to have important intracellular functions. From the sequence information available, it is possible that nucelobindins itself or nesfatin-1 like peptides within the NUCB1 could also elicit nesfatin-1-like biological functions. The research on nesfatin-1 in last 5years further adds to the importance of nucleobindins as potential endocrine precursors. This review aims to summarize some of the most recent findings on the functional significance of NUCB1, NUCB2, as well as encoded proteins and highlights the questions that remain unanswered. PMID:22154814

Gonzalez, Ronald; Mohan, Haneesha; Unniappan, Suraj

2012-05-01

387

Preparation of cuxinygazsen precursor films and powders by electroless deposition  

DOEpatents

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.

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

388

Pharmacological targeting of the ?-amyloid precursor protein intracellular domain  

PubMed Central

Amyloid precursor protein (APP) intracellular domain (AICD) is a product of APP processing with transcriptional modulation activity, whose overexpression causes various Alzheimer's disease (AD)-related dysfunctions. Here we report that 1-(3?,4?-dichloro-2-fluoro[1,1?-biphenyl]-4-yl)-cyclopropanecarboxylic acid) (CHF5074), a compound that favorably affects neurodegeneration, neuroinflammation and memory deficit in transgenic mouse models of AD, interacts with the AICD and impairs its nuclear activity. In neuroglioma-APPswe cells, CHF5074 shifted APP cleavage from A?42 to the less toxic A?38 peptide without affecting APP-C-terminal fragment, nor APP levels. As revealed by photoaffinity labeling, CHF5074 does not interact with ?-secretase, but binds to the AICD and lowers its nuclear translocation. In vivo treatment with CHF5074 reduced AICD occupancy as well as histone H3 acetylation levels and transcriptional output of the AICD-target gene KAI1. The data provide new mechanistic insights on this compound, which is under clinical investigation for AD treatment/prevention, as well as on the contribution of the AICD to AD pathology. PMID:24714650

Branca, Caterina; Sarnico, Ilenia; Ruotolo, Roberta; Lanzillotta, Annamaria; Viscomi, Arturo Roberto; Benarese, Marina; Porrini, Vanessa; Lorenzini, Luca; Calzà, Laura; Imbimbo, Bruno Pietro; Ottonello, Simone; Pizzi, Marina

2014-01-01

389

Proteolytic processing of Alzheimer’s ?-amyloid precursor protein  

PubMed Central

?–amyloid precursor protein (APP) is a critical factor in the pathogenesis of Alzheimer’s disease (AD). APP undergoes posttranslational proteolysis/processing to generate the hydrophobic ?-amyloid (A?) peptides. Deposition of A? in the brain, forming oligomeric A? and plaques, is identified as one of the key pathological hallmarks of AD. The processing of APP to generate A? is executed by ?- and ?-secretase and is highly regulated. A? toxicity can lead to synaptic dysfunction, neuronal cell death, impaired learning/memory and abnormal behaviors in AD models in vitro and in vivo. Aside from A?, proteolytic cleavages of APP can also give rise to the APP intracellular domain (AICD), reportedly involved in multiple types of cellular events such as gene transcription and apoptotic cell death. In addition to amyloidogenic processing, APP can also be cleaved by ?-secretase to form a soluble or secreted APP ectodomain (sAPP-?) that has been shown to be mostly neuro-protective. In this review, we describe the mechanisms involved in APP metabolism and the likely functions of its various proteolytic products to give a better understanding of the patho/physiological functions of APP. PMID:22122372

Zhang, Han; Ma, Qilin; Zhang, Yun-wu; Xu, Huaxi

2011-01-01

390

Glycosidically bound volatiles and flavor precursors in Laurus nobilis L.  

PubMed

Glycosidically bound volatile compounds in different parts (leaves and buds) of Laurus nobilis L. were investigated. After isolation of extracts obtained by Amberlite XAD-2 adsorption and methanol elution, glycosides were analyzed after enzymatic hydrolysis by GC-MS or directly after trifluoroacetyl (TFA) derivatization by GC-MS in EI and NCI mode. In the leaves most of the glycosidically bound volatiles occur as beta-D-glucopyranosides. Among the disaccharides, primeverosides are predominant; smaller amounts of alpha-L-arabinofuranosyl-beta-D-glucopyranosides, rutinosides, and vicianocides could also be identified. Major aglycons comprised benzyl alcohol, some linalool-diols, 2-hydroxy-1,8-cineole and its derivatives such as 2,3-dehydro-1,8-cineole, sobrerols, and menthadien-8-ols. Among the identified nor-carotenoids, 3-oxo-alpha-ionol, the corresponding 7,8-dihydro derivative, and vomifoliol are predominant in leaves. 3-Hydroxy-beta-damascone and 3-hydroxy-7,8-didehydro-beta-ionol, precursors of the sensorially active damascenone, were identified only in the buds. PMID:15769161

Kilic, Ayben; Kollmannsberger, Hubert; Nitz, Siegfried

2005-03-23

391

Neurogenin 2 Mediates Amyloid-? Precursor Protein-stimulated Neurogenesis.  

PubMed

Amyloid-? precursor protein (APP) is well studied for its role in Alzheimer disease, although its normal function remains uncertain. It has been reported that APP stimulates the proliferation and neuronal differentiation of neural stem/progenitor cells (NSPCs). In this study we examined the role of APP in NSPC differentiation. To identify proteins that may mediate the effect of APP on NSPC differentiation, we used a gene array approach to find genes whose expression correlated with APP-induced neurogenesis. We found that the expression of neurogenin 2 (Ngn2), a basic helix-loop-helix transcription factor, was significantly down-regulated in NSPCs from APP knock-out mice (APPKO) and increased in APP transgenic (Tg2576) mice. Ngn2 overexpression in APPKO NSPCs promoted neuronal differentiation, whereas siRNA knockdown of Ngn2 expression in wild-type NSPCs decreased neuronal differentiation. The results demonstrate that APP-stimulated neuronal differentiation of NSPCs is mediated by Ngn2. PMID:25217641

Bolós, Marta; Hu, Yanling; Young, Kaylene M; Foa, Lisa; Small, David H

2014-11-01

392

Astrocytes Promote TNF-Mediated Toxicity to Oligodendrocyte Precursors  

PubMed Central

Neuroinflammation and increased production of tumor necrosis factor (TNF) in the central nervous system have been implicated in many neurological diseases including white matter disorders periventricular leukomalacia and multiple sclerosis. However, the exact role of TNF in these diseases and how it mediates oligodendrocyte injury remain unclear. Previously we demonstrated that lipopolysaccharide (LPS) selectively kills oligodendrocyte precursors (preOLs) in a non-cell autonomous fashion through the induction of TNF in mixed glial cultures. Here we report that activation of oligodendroglial, but not astroglial and microglial, TNFR1 is required for LPS toxicity, and that astrocytes promote TNF-mediated preOL death through a cell contact-dependent mechanism. Microglia were the sole source for TNF production in LPS-treated mixed glial cultures. Ablation of TNFR1 in mixed glia completely prevented LPS-induced death of preOLs. TNFR1-expressing preOLs were similarly susceptible to LPS treatment when seeded into wildtype and TNFR1?/? mixed glial cultures, demonstrating a requirement for oligodendroglial TNFR1 in the cell death. Although exogenous TNF failed to cause significant cell death in enriched preOL cultures, it became cytotoxic when preOLs were in contact with astrocytes. Collectively, our results demonstrate oligodendroglial TNFR1 in mediating inflammatory destruction of preOLs and suggest a previously unrecognized role for astrocytes in promoting TNF toxicity to preOLs. PMID:21044081

Kim, SunJa; Steelman, Andrew J.; Koito, Hisami; Li, Jianrong

2010-01-01

393

Effect of soil heterogeneity on precursor events and landslide patterns  

NASA Astrophysics Data System (ADS)

Prediction of onset of hydrologically-induced shallow landslides is hampered by incomplete information regarding soil heterogeneity and hydrologic pathways which may result in abrupt and seemingly random soil mass release. Geomorphic and supplemental soil properties information is useful, but presently has been used primarily for producing conservative landslide susceptibility maps, disregarding the inherently local and progressive triggering mechanisms. We applied a physically-based hydro-mechanical landslide triggering model to systematically evaluate effects of soil heterogeneity on failure propagation and approach to criticality of a hillslope under hydrologic loading (rainfall). The model considers soil columns interconnected by mechanical bonds represented by virtual fiber bundles that capture multiscale mechanical elements (grain cementing agents, capillary water bonds, frictional forces and roots). The fiber bundle model capture progressive (local) failures that do not necessarily result in a landslide as load is redistributed to neighboring intact bonds. The accumulation and statistics of such precursor events reflect on the mechanical state of a hillslope and its attainment of criticality or eminent failure. The role of discontinuities in soil properties on the hydro-mechanical behavior of a hillslope and onset of landslide dynamics and patterns was studied numerically. Evidence suggest that with increasing degree of heterogeneity the likelihood of occurrence of large and disastrous landslide volumes diminishes due to multiple failure initiations at weak mechanical bonds disrupting and containing failed soil volumes.

Lehmann, P.; von Ruette, J.; Or, D.

2012-04-01

394

Childhood bestiality: a potential precursor to adult interpersonal violence.  

PubMed

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

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

2010-03-01

395

Geoelectric potential changes: Possible precursors to earthquakes in Japan  

PubMed Central

Whether electromagnetic precursors to earthquakes (EQs) exist is an important question not only for EQ prediction but also for understanding the physical processes of EQ generation. Slow transient geoelectric potential changes have been observed before several recent EQs in Japan. In most cases, they appeared 1–19 days before the EQs, and their duration and intensity were several minutes to 1 h and 1–2 mV/100 m. The changes appeared before five of all six EQs with magnitude ? 5 that occurred within 20 km of our stations during the observation period. Changes were also detected at greater epicentral distances (up to 75 km) before two other EQs, including one EQ of magnitude 4.7, which was preceded by a signal simultaneously recorded at three widely separated stations. These geoelectric potential changes have been distinguished through the following criteria from a multitude of other changes, which were noise of various origins. (i) The selected changes were proportional in amplitude to the length of the recording station's short (?100 m) dipoles and were simultaneously detected also on long (1–10 km) dipoles when the latter were in operation. (ii) No such changes occurred during the observation period that were not followed by EQs. Although the EQ precursory nature of these geoelectric potential changes is admittedly unproven, it seems that the present results warrant continued serious research into the occurrence, generation, and transmission of these signals and their possible causal relationship to EQs. PMID:10781060

Uyeda, S.; Nagao, T.; Orihara, Y.; Yamaguchi, T.; Takahashi, I.

2000-01-01

396

Regulation of Amyloid Precursor Protein Processing by Serotonin Signaling  

PubMed Central

Proteolytic processing of the amyloid precursor protein (APP) by the ?- and ?-secretases releases the amyloid-? peptide (A?), which deposits in senile plaques and contributes to the etiology of Alzheimer's disease (AD). The ?-secretase cleaves APP in the A? peptide sequence to generate soluble APP? (sAPP?). Upregulation of ?-secretase activity through the 5-hydroxytryptamine 4 (5-HT4) receptor has been shown to reduce A? production, amyloid plaque load and to improve cognitive impairment in transgenic mouse models of AD. Consequently, activation of 5-HT4 receptors following agonist stimulation is considered to be a therapeutic strategy for AD treatment; however, the signaling cascade involved in 5-HT4 receptor-stimulated proteolysis of APP remains to be determined. Here we used chemical and siRNA inhibition to identify the proteins which mediate 5-HT4d receptor-stimulated ?-secretase activity in the SH-SY5Y human neuronal cell line. We show that G protein and Src dependent activation of phospholipase C are required for ?-secretase activity, while, unexpectedly, adenylyl cyclase and cAMP are not involved. Further elucidation of the signaling pathway indicates that inositol triphosphate phosphorylation and casein kinase 2 activation is also a prerequisite for ?-secretase activity. Our findings provide a novel route to explore the treatment of AD through 5-HT4 receptor-induced ?-secretase activation. PMID:24466315

Pimenova, Anna A.; Thathiah, Amantha; De Strooper, Bart; Tesseur, Ina

2014-01-01

397

Pathways to adulthood and their precursors and outcomes.  

PubMed

Norway has an extensive welfare system which may provide adolescents with many options and high levels of flexibility in terms of pathways to adulthood. This study aimed to describe Norwegian developmental pathways to adulthood, including changes in role statuses (such as living situations, education, work, marriage/cohabitation and parenthood) from 16 to 30 years of age, and their precursors and outcomes. Repeated measures latent class analysis of longitudinal data from 998 Norwegian individuals indicated three main pathways to adulthood among women and men. In both sexes, most individuals undertook a long period of education and postponed family formation. However, some individuals started working early, a group of women established families with partners and children early, and a group of men remained primarily single between 16 and 30 years of age. Furthermore, the results show that pathways to adulthood in Norway are surprisingly similar to pathways in other countries such as the US, UK and Finland. The results indicate that pathways to adulthood are influenced by social reproduction factors in a country with high levels of welfare benefits as well. In addition, the results suggest that pathways involving living with a partner and either higher education or work are associated with high life satisfaction at age 30. PMID:24236443

Skogbrott Birkeland, Marianne; Leversen, Ingrid; Torsheim, Torbjørn; Wold, Bente

2014-02-01

398

Amyloid precursor protein processing is stimulated by metabotropic glutamate receptors.  

PubMed

Stimulation of muscarinic m1 or m3 receptors can, by generating diacylglycerol and activating protein kinase C, accelerate the breakdown of the amyloid precursor protein (APP) to form soluble, nonamyloidogenic derivatives (APPs), as previously shown. This relationship has been demonstrated in human glioma and neuroblastoma cells, as well as in transfected human embryonic kidney 293 cells and PC-12 cells. We now provide evidence that stimulation of metabotropic glutamate receptors (mGluRs), which also are coupled to phosphatidylinositol 4,5-bisphosphate hydrolysis, similarly accelerates processing of APP into nonamyloidogenic APPs. This process is demonstrated both in hippocampal neurons derived from fetal rats and in human embryonic kidney 293 cells transfected with cDNA expression constructs encoding the mGluR 1 alpha subtype. In hippocampal neurons, both an mGluR antagonist, L-(+)-2-amino-3-phosphonopropionic acid, and an inhibitor of protein kinase C, GF 109203X, blocked the APPs release evoked by glutamate receptor stimulation. Ionotropic glutamate agonists, N-methyl-D-aspartate or S(-)-5-fluorowillardiine, failed to affect APPs release. These data show that selective mGluR agonists that initiate signal-transduction events can regulate APP processing in bona fide primary neurons and transfected cells. As glutamatergic neurons in the cortex and hippocampus are damaged in Alzheimer disease, amyloid production in these regions may be enhanced by deficits in glutamatergic neurotransmission. PMID:7644542

Lee, R K; Wurtman, R J; Cox, A J; Nitsch, R M

1995-08-15

399

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

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

400

Testing secondary organic aerosol models using smog chamber data for complex precursor mixtures: influence of precursor volatility and molecular structure  

NASA Astrophysics Data System (ADS)

We use secondary organic aerosol (SOA) production data from an ensemble of unburned fuels measured in a smog chamber to test various SOA formation models. The evaluation considered data from 11 different fuels including gasoline, multiple diesels, and various jet fuels. The fuels are complex mixtures of species; they span a wide range of volatility and molecular structure to provide a challenging test for the SOA models. We evaluated three different versions of the SOA model used in the Community Multiscale Air Quality (CMAQ) model. The simplest and most widely used version of that model only accounts for the volatile species (species with less than or equal to 12 carbons) in the fuels. It had very little skill in predicting the observed SOA formation (R2 = 0.04, fractional error = 108%). Incorporating all of the lower-volatility fuel species (species with more than 12 carbons) into the standard CMAQ SOA model did not improve model performance significantly. Both versions of the CMAQ SOA model over-predicted SOA formation from a synthetic jet fuel and under-predicted SOA formation from diesels because of an overly simplistic representation of the SOA formation from alkanes that did not account for the effects of molecular size and structure. An extended version of the CMAQ SOA model that accounted for all organics and the influence of molecular size and structure of alkanes reproduced the experimental data. This underscores the importance of accounting for all low-volatility organics and information on alkane molecular size and structure in SOA models. We also investigated fitting an SOA model based solely on the volatility of the precursor mixture to the experimental data. This model could describe the observed SOA formation with relatively few free parameters, demonstrating the importance of precursor volatility for SOA formation. The exceptions were exotic fuels such as synthetic jet fuel that expose the central assumption of the volatility-dependent model that most emissions consist of complex mixtures with similar distribution of molecular classes. Despite its shortcomings, SOA formation as a function of volatility may be sufficient for modeling SOA formation in chemical transport models.

Jathar, S. H.; Donahue, N. M.; Adams, P. J.; Robinson, A. L.

2014-06-01

401

Cleavage of amyloid-beta precursor protein and amyloid-beta precursor-like protein by BACE 1.  

PubMed

Site-specific proteolysis of the amyloid-beta precursor protein (APP) by BACE 1 and gamma-secretase, a central event in Alzheimer disease, releases a large secreted extracellular fragment (called APP(S)), peptides of 40-43 residues derived from extracellular and transmembrane sequences (Abeta), and a short intracellular fragment (APP intracellular domain) that may function as a transcriptional activator in a complex with the adaptor protein Fe65 and the nuclear protein Tip60. APP is closely related to APP-like protein (APLP) 1 and APLP2, but only APP is known to be cleaved by BACE 1 and to be involved in Alzheimer disease. We now demonstrate that similar to APP, APLP1 and APLP2 are also cleaved by BACE 1 but not by ADAM 9, another APP protease, and also transactivate nuclear Tip60 in a complex with Fe65. Paradoxically, although BACE 1 cleavage appears to be specific for APP and APLPs, their cleavage sequences exhibit no homology, and a short sequence (7 amino acids) from APP that when placed close to the membrane converts a membrane protein that is normally not cleaved by BACE 1 into a BACE 1 substrate. Our data demonstrate that APLPs and APP are processed similarly to act via the same nuclear target, suggesting that BACE 1 cleavage regulates a common function of APP and APLPs in neurons. PMID:14699153

Li, Qiming; Südhof, Thomas C

2004-03-12

402

Lu2O3-SiO2-ZrO2 Coatings for Environmental Barrier Application by Solution Precursor Plasma Spraying and Influence of Precursor Chemistry  

NASA Astrophysics Data System (ADS)

As environmental barrier coatings are subjected to thermal stress in gas turbine engines, the introduction of a secondary phase as zircon (ZrSiO4) is likely to increase the stress resistance of Lu2Si2O7 coatings generated by induction plasma spraying using liquid precursors. In a first step, precursor chemistry effect is investigated by the synthesis of ZrO2-SiO2 nanopowders by induction plasma nanopowder synthesis technique. Tetraethyl orthosilicate (TEOS) as silicon precursor and zirconium oxynitrate and zirconium ethoxide as zirconium precursors are mixed in ethanol and produce a mixture of tetragonal zirconia and amorphous silica nanoparticles. The use of zirconium ethoxide precursor results in zirconia particles with diameter below 50 nm because of exothermic thermal decomposition of the ethoxide and its high boiling point with respect to solvent, while larger particles are formed when zirconium oxynitrate is employed. The formation temperature of zircon from zirconia and silica oxides is found at 1425 °C. Second, coatings are synthesized in Lu2O3-ZrO2-SiO2 system. After heat treatment, the doping effect of lutetium on zirconia grains totally inhibits the zircon formation. Dense coatings are obtained with the use of zirconium ethoxide because denser particles with a homogeneous diameter distribution constitute the coating.

Darthout, Émilien; Quet, Aurélie; Braidy, Nadi; Gitzhofer, François

2014-02-01

403

Vesicles in Experimental Chondrules as Clues to Chondrule Precursors  

NASA Astrophysics Data System (ADS)

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.

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

1993-07-01

404

Pyrolysis chemistry of polycarbosilane polymer precursors to ceramics  

NASA Astrophysics Data System (ADS)

The main theme of this research work was investigation of the precursor-ceramic conversion process for some polycarbosilane polymers, (-RRsp' SiCHsb2-)sb{n}, known as the poly(silylenemethylene)s (PSMs), where R and Rsp' are either hydrogen or bridging oxygen. The pyrolysis chemistry was characterized by elemental analysis, thermogravimetric analysis, liquid and solid state NMR spectroscopy, FTIR, and mass spectrometric analysis of the gaseous pyrolysis products. The strategy included three steps: First, linear poly(silaethylene), (SiHsb2CHsb2), PSE, was synthesized by ROP and examined as potential precursor to silicon carbide. This was one of the limiting cases where in (-RRsp' SiCHsb2-)sb{n}, R=Rsp'=H. The conversion process was studied by the examination of the gaseous species evolved during pyrolysis using a mass spectrometer. The results suggested that molecular H-transfer and elimination reactions involving silylene intermediates occurred initially and caused the crosslinking of the polymer between 300 and 420sp'C. Free radical reactions became operative and were the main mechanisms occurring above 420sp'C. The unusually high ceramic yield of linear PSE (ca. 80%) suggested that the SiHsb{x} groups in this polymer provided a latent reactivity that could be "turned on" by heating, thereby allowing the formation of a network structure that resists fragmentation. Second, polycarbosilane/siloxane hybrid polymers, (Si(O)CHsb2rbracksb{n}, were synthesized by sol-gel processing and were pyrolyzed to silicon oxycarbide ceramics. This was the other limiting case where in (-RRsp' SiCHsb2-)sb{n}, R=Rsp'=bridging or terminal oxygens. The gels were converted into silicon oxycarbides that contain a statistical distribution of the five possible SiCsb{4-x}Osb{x} environments between 600 and 1000sp'C. This rearrangement of the Si environments was attributed to the redistribution reactions involving the exchange of Si-O and Si-C bonds during the latter stages of the pyrolysis, likely facilitated by the Si-OH-induced attack on the Si-CHsb2-Si linkages. In addition, the microstructure of the gels and their pyrolytic products was investigated by Nsb2 adsorption-desorption test (the BET test). The results suggested that the investigated samples are microporous solids with relatively high surface areas even at 1000sp°C, indicating the potential interest of these samples as microporous materials. Finally, a mixture system was synthesized by introducing oxygen into the (SiHsb2CHsb2), polymer purposely to obtain a model (SiHsb2CHsb2rbracksb{n}rbrack Si(O)CHsb2rbracksb{m} system which has a variable and controllable amount of oxygen. This was the intermediate case between the two extremes. In this system, the pyrolysis mechanisms which worked in the two extreme cases also operated here along with a new mechanism resulting the formation of part of the total Hsb2 between Si-OH and Si-H groups.

Liu, Qi

405

Precursors to Forbush decreases in cosmic ray intensity and Space Weather predictions  

NASA Astrophysics Data System (ADS)

PRECURSORS TO FORBUSH DECREASES IN COSMIC RAY INTENSITY AND SPACE WEATHER PREDICTIONS Badruddin Department of Physics, Aligarh Muslim University, Aligarh-202002, India E-mail:badr_phys@redidfmail.com/Fax: +91-0571-701001 In this paper we examine the precursors to Forbush decreases by analyzing cosmic ray intensity recorded by ground based neutron detector. The precursors to Forbush decreases are examined in association with geomagnetic storms. Precursor to Forbush decreases of smaller amplitude (< 5 %) is enhanced diurnal anisotropy, and to Forbush decreases of larger amplitude (> 5 %) the precursor is an intensity deficitof cosmic rays (Sloss coneT type). Simultaneous analysis of solar wind, cosmic ray and geomagnetic data shows that precursors can be distinguished in terms of weaker and stronger interplanetary shocks responsible for Forbush decreases and geomagnetic storms. These precursors to Forbush decreases are of practical interest as possible predictors of Space Weather effects on earth several hours or even days before the passage of a major interplanetary shock. Our results show that such efforts may be useful input in Space Weather predictions.

Badruddin, B.

406

Precursors to potential severe core damage accidents: 1995 A status report  

SciTech Connect

Ten operational events that affected 10 commercial light-water reactors during 1995 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 1995 licensee event reports from commercial light-water reactors to identify those events that could potentially be precursors. Candidate precursors were 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 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 1984-1994 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 the events.

Belles, R.J.; Cletcher, J.W.; Copinger, D.A. [and others] and others

1997-04-01

407

Precursors to potential severe core damage accidents: 1997 -- A status report. Volume 26  

SciTech Connect

This report describes the five operational events in 1997 that affected five commercial light-water reactors (LWRs) and that are considered to be precursors to potential severe core damage accidents. 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 first computer-screening the 1997 licensee event reports from commercial LWRs to identify those events that could be precursors. Candidate precursors were 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 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--1996 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 the events.

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

1998-11-01

408

Immortalization of Neural Precursors When Telomerase Is Overexpressed in Embryonal Carcinomas and Stem Cells  

PubMed Central

The DNA repair enzyme telomerase maintains chromosome stability by ensuring that telomeres regenerate each time the cell divides, protecting chromosome ends. During onset of neuroectodermal differentiation in P19 embryonal carcinoma (EC) cells three independent techniques (Southern blotting, Q-FISH, and Q-PCR) revealed a catastrophic reduction in telomere length in nestin-expressing neuronal precursors even though telomerase activity remained high. Overexpressing telomerase protein (mTERT) prevented telomere collapse and the neuroepithelial precursors produced continued to divide, but deaggregated and died. Addition of FGF-2 prevented deaggregation, protected the precursors from the apoptotic event that normally accompanies onset of terminal neuronal differentiation, allowed them to evade senescence, and enabled completion of morphological differentiation. Similarly, primary embryonic stem (ES) cells overexpressing mTERT also initiated neuroectodermal differentiation efficiently, acquiring markers of neuronal precursors and mature neurons. ES precursors are normally cultured with FGF-2, and overexpression of mTERT alone was sufficient to allow them to evade senescence. However, when FGF-2 was removed in order for differentiation to be completed most neural precursors underwent apoptosis indicating that in ES cells mTERT is not sufficient allow terminal differentiation of ES neural precursors in vitro. The results demonstrate that telomerase can potentiate the transition between pluripotent stem cell and committed neuron in both EC and ES cells. PMID:18256293

Schwob, Anneke E.; Nguyen, Lilly J.

2008-01-01

409

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

SciTech Connect

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.

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

410

Analysis of Precursor Properties of mixed Al/Alumel Cylindrical Wire Arrays*  

NASA Astrophysics Data System (ADS)

Previous studies of mid-Z (Cu and Ni) cylindrical wire arrays (CWAs) on Zebra have found precursors with high electron temperatures of >300 eV. However, past experiments with Al CWAs did not find the same high temperature precursors. New precursor experiments using mixed Al/Alumel (Ni 95%, Si 2%, and Al 2%) cylindrical wire arrays have been performed to understand how the properties of L-shell Ni precursor will change and whether Al precursor will be observed. Time gated spectra and pinholes are used to determine precursor plasma conditions for comparison with previous Alumel precursor experiments. A full diagnostic set which included more than ten different beam-lines was implemented. Future work in this direction is discussed. [4pt] *This work was supported by NNSA under DOE Cooperative Agreements DE-FC52-06NA27588, and in part by DE-FC52-06NA27586, and DE-FC52-06NA27616. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000.

Stafford, A.; Safronova, A. S.; Kantsyrev, V. L.; Esaulov, A. A.; Weller, M. E.; Shrestha, I.; Osborne, G. C.; Shlyaptseva, V. V.; Keim, S. F.; Coverdale, C. A.; Chuvatin, A. S.

2012-10-01

411

Distinguishing Closely Related Amyloid Precursors Using an RNA Aptamer*  

PubMed Central

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 1H-15N 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

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.

2014-01-01

412

Effects of Sleep and Wake on Oligodendrocytes and Their Precursors  

PubMed Central

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

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

2013-01-01

413

Distinguishing closely related amyloid precursors using an RNA aptamer.  

PubMed

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

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

414

Amyloid precursor protein modulates ERK-1 and -2 signaling.  

PubMed

The amyloid precursor protein (APP) is a transmembrane protein with a short cytoplasmic tail whose physiological function is unclear, although it is well documented that the proteolytic processing of APP could influence the development of Alzheimer's disease (AD) through the formation of membrane-bound C-terminal fragments (CTFs) and of beta-amyloid peptides (Abeta). We have recently shown that tyrosine-phosphorylated APP and CTFs may interact with Grb2 and ShcA adaptor proteins and that this coupling occurs at a higher extent in AD subjects only. To study the interaction between APP or CTFs and ShcA/Grb2 and to investigate their molecular target we have used as experimental model two different cell lines: H4 human neuroglioma cells and APP/APLP null mouse embryonic fibroblast cells (MEFs). Here we show that in H4 cells APP interacts with Grb2; conversely in APP/APLP-null MEF cells this interaction is possible only after the reintroduction of human APP by transfection. We have also shown that in MEF cells the transfection of a plasmid encoding for human APP wild-type enhances the phosphorylation of ERK-1 and -2 as revealed by Western blotting and immunofluorescence experiments. Finally, also in H4 cells the overexpression of APP upregulates the levels of phospho-ERK-1 and -2. In summary our data suggest that APP may influence phospho-ERK-1 and -2 signaling through its binding with Grb2 and ShcA adaptors. The meaning of this event is not clear, but APP interaction with these adaptors could be relevant to regulate mitogenic pathway. PMID:17384289

Venezia, Valentina; Nizzari, Mario; Repetto, Emanuela; Violani, Elisabetta; Corsaro, Alessandro; Thellung, Stefano; Villa, Valentina; Carlo, Pia; Schettini, Gennaro; Florio, Tullio; Russo, Claudio

2006-12-01

415

Amyloid Precursor Protein Expression Modulates Intestine Immune Phenotype  

PubMed Central

Amyloid precursor protein (APP) is widely expressed across many tissue and cell types. Proteolytic processing of the protein gives rise to a plethora of protein fragments with varied biological activities. Although a large amount of data has been generated describing the metabolism of the protein in neurons, its role in regulating the phenotype of other cells remains unclear. Based upon prior work demonstrating that APP regulates the activation phenotype of monocytic lineage cells, we hypothesized that APP can regulate macrophage activation phenotype in tissues other than brain. Ileums of the small intestines from C57BL6/J wild type and APP?/? mice were compared as a representative tissue normally associated with abundant macrophage infiltration. APP?/? intestines demonstrated diminished CD68 immunoreactivity compared to wild type mice. This correlated with significantly less cycloxygenase-2 (cox-2), CD68, CD40, CD11c, and ?III-tubulin protein levels. Peritoneal macrophage from APP?/? mice demonstrated decreased in vitro migratory ability compared to wild type cells and diminished basal KC cytokine secretion. Whereas, APP?/? intestinal macrophage had an increase in basal KC cytokine secretion compared to wild type cells. Conversely, there was a significant decrease in multiple cytokine levels in APP?/? compared to wild type ileums. Finally, APP?/? mice demonstrated impaired absorption and increased motility compared to wild type mice. These data demonstrate the APP expression regulates immune cell secretions and phenotype and intestinal function. This data set describes a novel function for this protein or its metabolites that may be relevant not only for Alzheimer’s disease but a range of immune-related disorders. PMID:22124967

Puig, Kendra L.; Swigost, Adam J.; Zhou, Xudong; Sens, MaryAnn; Combs, Colin K.

2014-01-01

416

Carlactone is an endogenous biosynthetic precursor for strigolactones  

PubMed Central

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

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

2014-01-01

417

The ether lipid precursor hexadecylglycerol protects against Shiga toxins.  

PubMed

Shiga toxin-producing Escherichia coli bacteria cause hemorrhagic colitis and hemolytic uremic syndrome in humans. Currently, only supportive treatment is available for diagnosed patients. We show here that 24-h pretreatment with an ether lipid precursor, the alkylglycerol sn-1-O-hexadecylglycerol (HG), protects HEp-2 cells against Shiga toxin and Shiga toxin 2. Also the endothelial cell lines HMEC-1 and HBMEC are protected against Shiga toxins after HG pretreatment. In contrast, the corresponding acylglycerol, DL-?-palmitin, has no effect on Shiga toxicity. Although HG treatment provides a strong protection (~30 times higher IC50) against Shiga toxin, only a moderate reduction in toxin binding was observed, suggesting that retrograde transport of the toxin from the plasma membrane to the cytosol is perturbed. Furthermore, endocytosis of Shiga toxin and retrograde sorting from endosomes to the Golgi apparatus remain intact, but transport from the Golgi to the endoplasmic reticulum is inhibited by HG treatment. As previously described, HG reduces the total level of all quantified glycosphingolipids to 50-70 % of control, including the Shiga toxin receptor globotriaosylceramide (Gb3), in HEp-2 cells. In accordance with this, we find that interfering with Gb3 biosynthesis by siRNA-mediated knockdown of Gb3 synthase for 24 h causes a similar cytotoxic protection and only a moderate reduction in toxin binding (to 70 % of control cells). Alkylglycerols, including HG, have been administered to humans for investigation of therapeutic roles in disorders where ether lipid biosynthesis is deficient, as well as in cancer therapy. Further studies may reveal if HG can also have a therapeutic potential in Shiga toxin-producing E. coli infections. PMID:24740796

Bergan, Jonas; Skotland, Tore; Lingelem, Anne Berit Dyve; Simm, Roger; Spilsberg, Bjørn; Lindbäck, Toril; Sylvänne, Tuulia; Simolin, Helena; Ekroos, Kim; Sandvig, Kirsten

2014-11-01

418

Molecular cloning of three distinct cDNAs, each encoding a different adipokinetic hormone precursor, of the migratory locust, Locusta migratoria. Differential expression of the distinct adipokinetic hormone precursor genes during flight activity.  

PubMed

Three distinct cDNAs encoding the preproadipokinetic hormones I, II, and III (prepro-AKH I, II, and III), respectively, of Locusta migratoria have been isolated and sequenced. The three L. migratoria AKH precursors have an overall architecture similar to that of other precursors of the AKH/red pigment-concentrating hormone (RPCH) family identified so far. The AKH I and II precursors of L. migratoria are highly homologous to the Schistocerca gregaria and Schistocerca nitans AKH precursors. Although the L. migratoria AKH III precursor appears to be the least homologous to the Manduca sexta, Drosophila melanogaster, and Carcinus maenas AKH/RPCH precursors, we favor the opinion that the L. migratoria AKH III precursor is evolutionary more related to the M. sexta, D. melanogaster, and C. maenas AKH/RPCH precursors than to the AKH I and II precursors of S. gregaria, S. nitans, or L. migratoria. In situ hybridization showed signals for the different AKH mRNAs to be co-localized in cell bodies of the glandular lobes of the corpora cardiaca. Northern blot analysis revealed the presence of single mRNA species encoding the AKH I precursor (approximately 570 bases), AKH II precursor (approximately 600 bases), and AKH III precursor (approximately 670 bases), respectively. Interestingly, flight activity increased steady-state levels of the AKH I and II mRNAs (approximately 2.0 times each) and the AKH III mRNA (approximately 4.2 times) in the corpora cardiaca. PMID:7559443

Bogerd, J; Kooiman, F P; Pijnenburg, M A; Hekking, L H; Oudejans, R C; Van der Horst, D J

1995-09-29

419

A precursor approach to the synthesis and fabrication of conducting polymers  

NASA Astrophysics Data System (ADS)

Poly(terthiophene) nanostructures consisting of periodic nanolines were prepared using the precursor polymer approach in conjunction with nanoimprint lithography. Precursor poly(norbornylene)s consisting of terthiophene side chains were prepared from their corresponding norbornylene monomers via ring opening metathesis polymerization. A copolymer consisting of terthiophene norbornylene and acetate norbornylene repeat units with a 50:50 composition exhibited a glass transition temperature of 52°C. Nanolines of percursor polynorbornylene were prepared by thermal nanoimprint lithography. The nanoimprinted precursor polymer was then converted to conjugated conductive polymer via chemical and electrochemical oxidation of the terthiophene side units. Nanoimprinted lines of conductive poly(terthiophene) exhibited high electrochromic contrast at 437 nm. Poly(arylenesilylene)s showed the promising aspects as a precursor polymer to form conducting polymers via oxidative electrochemical or chemical desilylation. Poly(arylenesilylene)s can be prepared in one pot reaction and their physical properties can be tuned by introducing different silane derivatives. Poly[(2,2'-bithienylene)dimethylsilylene] was prepared by coupling reaction between dilithiated 2,2'-bithiophene and dichlorodimethylsilane. Conversion of the precursor polymer to poly(bithiophene) was carried out via solid state electrochemical oxidation and confirmed by optical and electrochemical analyses. As a demonstration, poly[(2,2'-bithienylene)dimethylsilylene] was melt drawn into a fiber and converted to the poly(bithiophene) via solid state oxidative electrochemical conversion. Solution processable poly(arylenesilylene)s were prepared by introducing silanes having longer alkyl groups than methyl groups. Nanofibers of precursor polymers were obtained from precursor polymer solutions via electrospinning. The formation of poly(bithiophene) fibers via the solid-state oxidative conversion of electrospun precursor poly(bithienylenesilylene) nanofibers was confirmed electrochemically. The conductive polymer nanofiber mat obtained from the precursor polymer showed the similar electrochromic functionality to that of poly(bithiophene).

Choi, Jia

420

Influence of precursor heating on viscous flow around a Jovian entry body  

NASA Technical Reports Server (NTRS)

The influence of changes in precursor region flow properties (resulting from the absorption of radiation from the shock layer) on the entire shock layer flow phenomena was investigated. The axially symmetric case is considered for both the preheating zone (precursor region) and shock layer. The flow in the shock layer is assumed to be viscous with chemical equilibrium but radiative nonequilibrium. Realistic thermophysical and spectral models are employed, and results are obtained by implicit finite difference and iterative procedures. The results indicate that precursor heating increases the radiative heating of the body by a maximum of 7.5 percent for 116 km entry conditions.

Tiwari, S. N.; Szema, K. Y.

1979-01-01

421

Synthesis of anhydride precursors of the environment-sensitive fluorophores 4-DMAP and 6-DMN.  

PubMed

This protocol describes the synthesis of cyclic anhydride precursors of the environment-sensitive fluorophores 4-dimethylaminophthalimide (4-DMAP) and 6-dimethylaminonaphthalimide (6-DMN). The condensation of these anhydrides with a primary amino group confers on molecules of interest solvatochromic properties. In particular, two strategies for the insertion of the chromophores into peptides are presented in two companion protocols. The anhydride syntheses can be completed on the gram scale in 2 d for the 4-DMAP precursor and 10-15 d for the 6-DMN precursor. PMID:18079722

Sainlos, Matthieu; Imperiali, Barbara

2007-01-01

422

Effect of solution concentration on splat formation and coating microstructure using the solution precursor plasma spray process  

Microsoft Academic Search

The Solution Precursor Plasma Spray (SPPS) process had been successfully used to deposit 7YSZ thermal barrier coatings. In this research, the effects of solution precursor concentration on 7YSZ splat formation and coating microstructure are studied. With increasing solution concentration, solution viscosity increases and surface tension decreases. Solution concentration has no effect on precursor pyrolysis and crystallization temperatures. The average atomized

Dianying Chen; Eric H. Jordan; Maurice Gell

2008-01-01

423

Local Sonic Hedgehog Signaling Regulates Oligodendrocyte Precursor Appearance in Multiple Ventricular Zone Domains in the Chick Metencephalon  

Microsoft Academic Search

In the chick metencephalon, oligodendrocyte precursors arise in distinct domains of the ventricular zone. During development, the earliest oligodendrocyte precursors appear in the metencephalic ventral ventricular zone adjacent to the midline, consistent with their location in the spinal cord. In contrast to spinal cord, however, distinct domains in the lateral and dorsal metencephalic ventricular zone subsequently generate oligodendrocyte precursors. All

Jeannette E. Davies; Robert H. Miller

2001-01-01

424

July 16, 2009 20:51 Waves in Random and Complex Media 0907precursor Waves in Random and Complex Media  

E-print Network

July 16, 2009 20:51 Waves in Random and Complex Media 0907precursor Waves in Random and Complex Media Vol. 00, No. 00, July 2009, 1­30 RESEARCH ARTICLE Fractional Precursors in Random Media Josselin heterogeneous and multiscale media. The shape of the precursor and its fractional power law decay

Solna, Knut

425

Pyrolysis Pathways of Sulfonated Polyethylene, an Alternative Carbon Fiber Precursor  

SciTech Connect

Sulfonated polyethylene is an emerging precursor for the production of carbon fibers. Pyrolysis of sulfonated polyethylene was characterized by thermogravimetric analysis (TGA). n-heptane-4-sulfonic acid (H4S) was selected as a model compound for the study of sulfonated polyethylene. Density functional theory and conventional transition state theory were used to determine the rate constants of pyrolysis for H4S from 300-1000 K. Multiple reaction channels from two different mechanisms were explored: 1) internal five-centered elimination (Ei 5) and 2) radical chain reaction. The pyrolysis of H4S was simulated with kinetic Monte Carlo (kMC) to obtain TGA plots that compared favorably to experiment. We observed that at tem- peratures < 550 K, the radical mechanism was dominant and yielded the trans-alkene, whereas cis-alkene was formed at higher temperatures from the internal elimination. The maximum rates of % mass loss became independent of initial OH radical concentration at 440-480 K. Experimentally, the maximum % mass loss occurred from 440-460 K (heating rate dependent). Activation energies derived from the kMC-simulated TGAs of H4S (26-29 kcal/mol) agreed with experiment for sulfonated polyethylene ( 31 kcal/mol). The simulations revealed that in this region, decomposition of radical HOSO2 became competitive to H abstraction by HOSO2, making OH the carrying radical for the reaction chain. The maximum rate of % mass loss for internal elimination was observed at temperatures > 600 K. Low-scale carbonization utilizes temperatures < 620 K; thus, internal elimination will not be competitive. Ei5 elimination has been studied for sulfoxides and sulfones, but this represents the first study of internal elimination in sulfonic acids. Nonlinear Arrhenius plots were found for all bimolecular reactions. The most significant nonlinear behavior was observed for reactions where the barrier was small. For reactions with low activation barriers, nonlinearity was traced to conflicting trends between the exponential temperature dependence of the energetic term and the temperature dependence of the vibrational partition function of the transitional modes.

Younker, Jarod M [ORNL; Saito, Tomonori [ORNL; Hunt, Marcus A [ORNL; Beste, Ariana [ORNL; Naskar, Amit K [ORNL

2013-01-01

426

Air Quality Modeling of Ozone Radical Precursors in Houston  

NASA Astrophysics Data System (ADS)

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.

Rappenglueck, B.; Czader, B.; Li, X.

2013-05-01

427

Purification and aggregation of the amyloid precursor protein intracellular domain.  

PubMed

Amyloid precursor protein (APP) is a type I transmembrane protein associated with the pathogenesis of Alzheimer's disease (AD). APP is characterized by a large extracellular domain and a short cytosolic domain termed the APP intracellular domain (AICD). During maturation through the secretory pathway, APP can be cleaved by proteases termed ?, ?, and ?-secretases. Sequential proteolytic cleavage of APP with ? and ?-secretases leads to the production of a small proteolytic peptide, termed A?, which is amyloidogenic and the core constituent of senile plaques. The AICD is also liberated from the membrane after secretase processing, and through interactions with Fe65 and Tip60, can translocate to the nucleus to participate in transcription regulation of multiple target genes. Protein-protein interactions involving the AICD may affect trafficking, processing, and cellular functions of holo-APP and its C-terminal fragments. We have recently shown that AICD can aggregate in vitro, and this process is inhibited by the AD-implicated molecular chaperone ubiquilin-1. Consistent with these findings, the AICD has exposed hydrophobic domains and is intrinsically disordered in vitro, however it obtains stable secondary structure when bound to Fe65. We have proposed that ubiquilin-1 prevents inappropriate inter- and intramolecular interactions of AICD, preventing aggregation in vitro and in intact cells. While most studies focus on the role of APP in the pathogenesis of AD, the role of AICD in this process is not clear. Expression of AICD has been shown to induce apoptosis, to modulate signaling pathways, and to regulate calcium signaling. Over-expression of AICD and Fe65 in a transgenic mouse model induces Alzheimer's like pathology, and recently AICD has been detected in brain lysates by western blotting when using appropriate antigen retrieval techniques. To facilitate structural, biochemical, and biophysical studies of the AICD, we have developed a procedure to produce recombinantly large amounts of highly pure AICD protein. We further describe a method for inducing the in vitro thermal aggregation of AICD and analysis by atomic force microscopy. The methods described are useful for biochemical, biophysical, and structural characterization of the AICD and the effects of molecular chaperones on AICD aggregation. PMID:22952038

El Ayadi, Amina; Stieren, Emily S; Barral, José M; Oberhauser, Andres F; Boehning, Darren

2012-01-01

428

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

E-print Network

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...

Zhu, Wan Wen

2012-10-19

429

Classification and concentration estimation of explosive precursors using nanowires sensor array and decision tree learning  

NASA Astrophysics Data System (ADS)

This paper aims to classify and estimate concentrations of explosive precursors using a nanowire sensor array and decision tree learning algorithm. The nanowire sensor array consists of tin oxide sensors with four different additives, platinum (Pt), copper (Cu), indium (In), and nickel (Ni). The nanowire sensor array was tested using the vapors from four explosives precursors, acetone, nitrobenzene, nitrotoluene, and octane with 10 different concentration levels each. A pattern recognition technique based on decision tree learning was applied to classify the explosive precursors and estimate their concentration. Classification and regression tree (CART) analysis was used for classification. The CART was also utilized for the purpose of structure identification in Sugeno fuzzy inference system (FIS) for estimating the concentration of the precursors. Two CARTs were trained and their testing results were investigated.

Cho, Junghwan; Li, Xiaopeng; Gu, Zhiyong; Kurup, Pradeep

2011-09-01

430

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

E-print Network

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 ...

Sarell, Claire J.

431

Optical precursors with competing linear and nonlinear dispersions in quantum dot molecules  

NASA Astrophysics Data System (ADS)

We theoretically investigate coherent control of optical precursors in quantum-dot molecules by voltage-controlled tunneling. When the probe field is weak, the linear susceptibility shows normal dispersion. The main signal is delayed due to slow-light effect and optical precursors are separated from the incident pulse. As increase of the probe-field intensity, the nonlinearity arises. The enhanced self-Kerr nonlinearity exhibits anomalous dispersion, then the main signal is accelerated and constructively interferes with the precursors, so a strong transient pulse appears. Simulation result shows that its peak value is about one order of magnitude larger than that of the incident pulse. The competition between the linear and nonlinear dispersions contributes to the separation and enhancement of the optical precursors.

Peng, Yandong; Yang, Aihong; Chen, Bing; Xu, Yan; Zhang, Luyin

2014-11-01

432

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

PubMed

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

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

2014-11-28