Redacting with Confidence: How to Safely Publish Sanitized Reports Converted from Word to PDF

DTIC Science & Technology

2006-02-02

select Insert->Picture-> Autoshapes from the top menu bar (this opens the AutoShapes toolbar). Select the rectangle from the Autoshapes toolbar as in... AutoShape from the menu as in Figure 6 (this opens the Format AutoShape dialog box), select the Size tab, enter the desired height and width of the

The role of preliminary magazine training in acquisition of the autoshaped key peck1

PubMed Central

Davol, G. H.; Steinhauer, G. D.; Lee, A.

1977-01-01

A series of experiments tested the hypothesis that initial key pecks in the autoshaping procedure are generalized pecks at the illuminated grain hopper. Experiment I found that autoshaping readily occurred when the chamber was continuously illuminated by a house-light. In Experiment II, pigeons given magazine training and autoshaping with an unlighted grain hopper failed to autoshape in 200 trials. Acquisition of autoshaped key pecking was retarded in Experiment III when stimulus control by the magazine light was reduced. In the fourth study, pigeons were given magazine training with either a red or white magazine light and then given autoshaping with concurrently presented red and white keys. For all pigeons in this experiment, the first key peck occurred on the key of the same color as that pigeon's magazine light. The results of these experiments were interpreted as supporting an account of autoshaping that identifies initial key pecks as arising due to generalization of pecking at the lighted grain hopper to pecking at the lighted key. PMID:16812027

Pavlovian autoshaping procedures increase plasma corticosterone and levels of norepinephrine and serotonin in prefrontal cortex in rats.

PubMed

Tomie, Arthur; Tirado, Aidaluz D; Yu, Lung; Pohorecky, Larissa A

2004-08-12

Pavlovian autoshaping procedures provide for pairings of a small object conditioned stimulus (CS) with a rewarding substance unconditioned stimulus (US), resulting in the acquisition of complex sequences of CS-directed skeletal-motor responses or autoshaping conditioned responses (CRs). Autoshaping procedures induce higher post-session levels of corticosterone than in controls receiving CS and US randomly, and the enhanced post-session corticosterone levels have been attributed to the appetitive or arousal-inducing effects of autoshaping procedures. Enhanced corticosterone release can be induced by aversive stimulation or stressful situations, where it is often accompanied by higher levels of norepinephrine (NE) and serotonin (5-HT) in prefrontal cortex (PFC) but not in striatum (ST). Effects of autoshaping procedures on post-session corticosterone levels, NE contents in PFC, and 5-HT contents in PFC and ST were investigated in male Long-Evans rats. Post-session blood samples revealed higher corticosterone levels in the CS-US Paired group (n = 46) than in the CS-US Random control group (n = 21), and brain samples revealed higher levels of PFC NE and 5-HT in CS-US Paired group. Striatal 5-HT levels were unaltered by the autoshaping procedures. Autoshaping procedures provide for appetitive stimulation and induce an arousal-like state, as well as simultaneous stress-like changes in plasma corticosterone and monoamine levels in PFC. Autoshaping, therefore, may be useful for the study of endocrine and central processes associated with appetitive conditions.

Effects of short-term hormonal replacement on learning and on basal forebrain ChAT and TrkA content in ovariectomized rats.

PubMed

Espinosa-Raya, Judith; Plata-Cruz, Noemí; Neri-Gómez, Teresa; Camacho-Arroyo, Ignacio; Picazo, Ofir

2011-02-23

It has been proposed that sex steroid hormones improve performance in some cognitive tasks by regulating the basal forebrain cholinergic function. However, the molecular basis of such influence still remains unknown. Current study analyzed the performance of ovariectomized rats in an autoshaping learning task after a short-term treatment with 17β-estradiol (E2: 4 and 40μg/kg) and/or progesterone (P4: 4mg/kg). These results were correlated with basal forebrain choline acetyltransferase (ChAT) and TrkA protein content. The high dose of E2 enhanced both acquisition in the autoshaping task and the content of ChAT and TrkA. P4 treatment increased ChAT and TrkA content without affecting performance of rats in the autoshaping learning task. Interestingly, the continuous and simultaneous administration of E2 plus P4 did not significantly modify behavioral and biochemical evaluated parameters. These results address the influence of both E2 and P4 on cholinergic and TrkA activity and suggest that the effects of ovarian hormones on cognitive performance involve basal forebrain cholinergic neurons. Copyright © 2010 Elsevier B.V. All rights reserved.

Pedunculopontine tegmental nucleus lesions impair stimulus--reward learning in autoshaping and conditioned reinforcement paradigms.

PubMed

Inglis, W L; Olmstead, M C; Robbins, T W

2000-04-01

The role of the pedunculopontine tegmental nucleus (PPTg) in stimulus-reward learning was assessed by testing the effects of PPTg lesions on performance in visual autoshaping and conditioned reinforcement (CRf) paradigms. Rats with PPTg lesions were unable to learn an association between a conditioned stimulus (CS) and a primary reward in either paradigm. In the autoshaping experiment, PPTg-lesioned rats approached the CS+ and CS- with equal frequency, and the latencies to respond to the two stimuli did not differ. PPTg lesions also disrupted discriminated approaches to an appetitive CS in the CRf paradigm and completely abolished the acquisition of responding with CRf. These data are discussed in the context of a possible cognitive function of the PPTg, particularly in terms of lesion-induced disruptions of attentional processes that are mediated by the thalamus.

Effects of lesions of the amygdala central nucleus on autoshaped lever pressing

PubMed Central

Chang, Stephen E.; Wheeler, Daniel S.; Holland, Peter C.

2012-01-01

Neutral cues paired with rewards often appear to acquire motivational significance, as if the incentive motivational value of the reward is transferred to the cue. Such cues have been reported to modulate the performance of instrumental action (Pavlovian-instrumental transfer, PIT), serve as conditioned reinforcers in the establishment of new learning, and be the targets of approach and other cue-directed behaviors. Here we examined the effects of lesions of the amygdala central nucleus (CeA) on the acquisition of discriminative autoshaped lever-pressing. Insertion of one lever into the experimental chamber was reinforced by sucrose delivery, but insertion of another lever was not reinforced. Although sucrose delivery was not contingent on lever pressing, both CeA- and sham-lesioned rats rapidly came to press the reinforced but not the nonreinforced lever. Despite their showing little evidence of impairments in autoshaped lever pressing, these same CeA-lesioned rats showed significant deficits in the expression of PIT in a subsequent phase of the experiment. The lack of impaired autoshaping in CeA-lesioned rats contrasts with effects previously reported for conditioned orienting responses (ORs) and for other putative measures of incentive learning including PIT and conditioned approach to visual cues. PMID:22386516

Autoshaping, random control, and omission training in the rat1

PubMed Central

Locurto, Charles; Terrace, H. S.; Gibbon, John

1976-01-01

The role of the stimulus-reinforcer contingency in the development and maintenance of lever contact responding was studied in hooded rats. In Experiment I, three groups of experimentally naive rats were trained either on autoshaping, omission training, or a random-control procedure. Subjects trained by the autoshaping procedure responded more consistently than did either random-control or omission-trained subjects. The probability of at least one lever contact per trial was slightly higher in subjects trained by the omission procedure than by the random-control procedure. However, these differences were not maintained during extended training, nor were they evident in total lever-contact frequencies. When omission and random-control subjects were switched to the autoshaping condition, lever contacts increased in all animals, but a pronounced retardation was observed in omission subjects relative to the random-control subjects. In addition, subjects originally exposed to the random-control procedure, and later switched to autoshaping, acquired more rapidly than naive subjects that were exposed only on the autoshaping procedure. In Experiment II, subjects originally trained by an autoshaping procedure were exposed either to an omission, a random-control, or an extinction procedure. No differences were observed among the groups either in the rate at which lever contacts decreased or in the frequency of lever contacts at the end of training. These data implicate prior experience in the interpretation of omission-training effects and suggest limitations in the influence of stimulus-reinforcer relations in autoshaping. PMID:16811960

Autoshaping, random control, and omission training in the rat.

PubMed

Locurto, C; Terrace, H S; Gibbon, J

1976-11-01

The role of the stimulus-reinforcer contingency in the development and maintenance of lever contact responding was studied in hooded rats. In Experiment I, three groups of experimentally naive rats were trained either on autoshaping, omission training, or a random-control procedure. Subjects trained by the autoshaping procedure responded more consistently than did either random-control or omission-trained subjects. The probability of at least one lever contact per trial was slightly higher in subjects trained by the omission procedure than by the random-control procedure. However, these differences were not maintained during extended training, nor were they evident in total lever-contact frequencies. When omission and random-control subjects were switched to the autoshaping condition, lever contacts increased in all animals, but a pronounced retardation was observed in omission subjects relative to the random-control subjects. In addition, subjects originally exposed to the random-control procedure, and later switched to autoshaping, acquired more rapidly than naive subjects that were exposed only on the autoshaping procedure. In Experiment II, subjects originally trained by an autoshaping procedure were exposed either to an omission, a random-control, or an extinction procedure. No differences were observed among the groups either in the rate at which lever contacts decreased or in the frequency of lever contacts at the end of training. These data implicate prior experience in the interpretation of omission-training effects and suggest limitations in the influence of stimulus-reinforcer relations in autoshaping.

Spectral Irradiance Calibration in the Infrared. XVI. Improved Accuracy in the Infrared Spectra of the Secondary and Tertiary Standard Calibration Stars

DTIC Science & Technology

2006-10-01

2004); (A) autoshape (see text). The number in brackets is the wavelength (in microns) at which that segment ends. The first segment starts at 1 pm...and is produced with autoshape . Where available, the Strecker et al. (1979) data cover 1.2-2.36 pm; otherwise, autoshape is used. The SWS spectra all...uncertainties are listed Table 2. The stars in parameter function autoshape , which was developed to fit the Table 1 are original Cohen et al. secondary

A look at Behaviourism and Perceptual Control Theory in Interface Design

DTIC Science & Technology

1998-02-01

behaviours such as response variability, instinctive drift, autoshaping , etc. Perceptual Control Theory (PCT) postulates that behaviours result from the...internal variables. Behaviourism, on the other hand, can not account for variability in responses, instinctive drift, autoshaping , etc. Researchers... Autoshaping . Animals appear to learn without reinforcement. However, conditioning theory speculates that learning results only when reinforcement

Errorless discrimination established by differential autoshaping1

PubMed Central

Wilkie, Donald M.; Ramer, Donald G.

1974-01-01

In Experiment I, pigeons exposed to a differential autoshaping procedure pecked a key in the presence of the stimulus associated with reinforcement but did not peck, or pecked infrequently, in the presence of the stimulus associated with nonreinforcement. In Experiment II, pigeons were exposed to a differential autoshaping procedure in which one stimulus was associated with reinforcement and two stimuli were associated with nonreinforcement. The birds initially responded in the presence of one stimulus associated with nonreinforcement but never responded in the presence of the second stimulus associated with nonreinforcement. They were subsequently exposed to an autoshaping procedure in which reinforcement followed both these stimuli. The number of stimulus-reinforcement pairings required to establish pecking in the presence of the stimulus during which responses had not previously occurred suggested that such stimuli are inhibitory. These findings have implications for autoshaping, errorless discrimination, inhibition, and theories of discrimination byproducts. PMID:16811797

Errorless discrimination established by differential autoshaping.

PubMed

Wilkie, D M; Ramer, D G

1974-09-01

In Experiment I, pigeons exposed to a differential autoshaping procedure pecked a key in the presence of the stimulus associated with reinforcement but did not peck, or pecked infrequently, in the presence of the stimulus associated with nonreinforcement. In Experiment II, pigeons were exposed to a differential autoshaping procedure in which one stimulus was associated with reinforcement and two stimuli were associated with nonreinforcement. The birds initially responded in the presence of one stimulus associated with nonreinforcement but never responded in the presence of the second stimulus associated with nonreinforcement. They were subsequently exposed to an autoshaping procedure in which reinforcement followed both these stimuli. The number of stimulus-reinforcement pairings required to establish pecking in the presence of the stimulus during which responses had not previously occurred suggested that such stimuli are inhibitory. These findings have implications for autoshaping, errorless discrimination, inhibition, and theories of discrimination byproducts.

Behavioral predictors of alcohol drinking in a neurodevelopmental rat model of schizophrenia and co-occurring alcohol use disorder.

PubMed

Khokhar, Jibran Y; Todd, Travis P

2018-04-01

Alcohol use disorder commonly occurs in patients with schizophrenia and contributes greatly to its morbidity. Unfortunately, the neural and behavioral underpinnings of alcohol drinking in these patients are not well understood. In order to begin to understand the cognitive and reward-related changes that may contribute to alcohol drinking, this study was designed to address: 1) latent inhibition; 2) conditioning; and 3) extinction of autoshaping in a neurodevelopmental rat model with relevance to co-occurring schizophrenia and alcohol use disorders, the neonatal ventral hippocampal lesioned (NVHL) rat. NVHL lesions (or sham surgeries) were performed on post-natal day 7 (PND7) and animals were given brief exposure to alcohol during adolescent (PND 28-42). Latent inhibition of autoshaping, conditioning and extinction were assessed between PND 72-90. On PND90 animals were given alcohol again and allowed to establish stable drinking. Latent inhibition of autoshaping was found to be prolonged in the NVHL rats; the NVHL rats pre-exposed to the lever stimulus were slower to acquire autoshaping than sham pre-exposed rats. NVHL rats that were not pre-exposed to the lever stimulus did not differ during conditioning, but were slower to extinguish conditioned responding compared to sham controls. Finally, the NVHL rats from both groups drank significantly more alcohol than sham rats, and the extent of latent inhibition predicted future alcohol intake in the pre-exposed animals. These findings suggest that the latent inhibition of autoshaping procedure can be used to model cognitive- and reward-related dysfunctions in schizophrenia, and these dysfunctions may contribute to the development of co-occurring alcohol use. Copyright © 2017 Elsevier B.V. All rights reserved.

Lesions to the subthalamic nucleus decrease impulsive choice but impair autoshaping in rats: the importance of the basal ganglia in Pavlovian conditioning and impulse control.

PubMed

Winstanley, Catharine A; Baunez, Christelle; Theobald, David E H; Robbins, Trevor W

2005-06-01

Although the subthalamic nucleus (STN) is involved in regulating motor function, and inactivation of this structure relieves the motor symptoms in Parkinsonian patients, recent data indicate that corticosubthalamic connections are involved in both the regulation of attention and the ability to withhold from responding. Considerable evidence suggests that the neural circuitry underlying such behavioural disinhibition or impulsive action can be at least partially dissociated from that implicated in impulsive decision-making and it has been suggested that the tendency to choose impulsively is related to the ability to form and use Pavlovian associations. To explore these hypotheses further, STN-lesioned rats were tested on the delay-discounting model of impulsive choice, where impulsivity is defined as the selection of a small immediate over a larger delayed reward, as well as in a rodent autoshaping paradigm. In contrast to previous reports of increased impulsive action, STN lesions decreased impulsive choice but dramatically impaired the acquisition of the autoshaping response. When the STN was lesioned after the establishment of autoshaping behaviour, lesioned subjects were more sensitive to the omission of reward, indicative of a reduction in the use of Pavlovian associations to control autoshaping performance. These results emphasize the importance of the STN in permitting conditioned stimulus-unconditioned stimulus associations to regulate goal-seeking, a function which may relate to the alterations in impulsive choice observed in the delay-discounting task. These data bear a striking similarity to those observed after lesions of the orbitofrontal cortex and are suggestive of an important role for corticosubthalamic connections in complex cognitive behaviour.

Learning and Memory Enhancement by Neuropeptides

DTIC Science & Technology

1987-12-31

extxosure to other toxicants ,’e.g. other heavy metals, organic solvents), or arising from disease statee. We study leaming ii, an autoshaping task...Sparber, S.B. Selective leaming impairment of j delayed reinforcement autoshaped behavior caused by low doses of trimethyltin. S EPsychopharn-.acology...impairs acquis:tion of autoshaped behavior, whether given before or after training sessions. manuscript des -")ing this work is in preparation, and an

Semantically Grounded Briefings

DTIC Science & Technology

2005-12-01

cascading interface, mirroring the class inheritance of the ontologies. Clicking on one of these tools, like PowerPoint’s native autoshape tools...connections are their graphic templates. This determines the appearance of an instance of that concept. Any of PowerPoint’s native autoshapes , formatted...which can be any PowerPoint autoshape , group shape, or image • Identification of a modulated component of C’s graphic template. If C’s graphic

Gustatory thalamus lesions in the rat: III. Simultaneous contrast and autoshaping.

PubMed

Reilly, S; Pritchard, T C

1997-12-01

The performance of rats with electrophysiologically guided electrolytic lesions of the gustatory thalamus (GT) was compared to that of control subjects in two experiments. In Experiment 1, the lesioned rats showed normal simultaneous contrast effects (both positive and negative) during brief, alternating access to 0.15% saccharin and 1.0 M sucrose. There was, however, a substantial lesion-induced impairment in the level of conditioned stimulus-directed maintenance responding on the autoshaping procedure of Experiment 2. These findings are discussed with respect to the anticipatory contrast deficit recently reported in GT-lesioned rats.

Learing and Memory Enhancement by Neuropeptides

DTIC Science & Technology

1989-09-27

autoshaping task, in which rats learn to touch a lever to obtain food. Substantial progress towards the goals of the project were made, especially...impairment of "delayed reinforcement autoshaped behavior caused by low doses of trimethyltin, Psychxoharmacology 93(1987): 301-307. S.B. Sparber, C.A...impairs autoshaped learning. Behavioral and Neural Biolog 51 (1989)34-45. The following papers have been submitted for publication: b -~iL101 Rita B

Autoshaped choice in artificial neural networks: implications for behavioral economics and neuroeconomics.

PubMed

Burgos, José E; García-Leal, Óscar

2015-05-01

An existing neural network model of conditioning was used to simulate autoshaped choice. In this phenomenon, pigeons first receive an autoshaping procedure with two keylight stimuli X and Y separately paired with food in a forward-delay manner, intermittently for X and continuously for Y. Then pigeons receive unreinforced choice test trials of X and Y concurrently present. Most pigeons choose Y. This preference for a more valuable response alternative is a form of economic behavior that makes the phenomenon relevant to behavioral economics. The phenomenon also suggests a role for Pavlovian contingencies in economic behavior. The model used, in contrast to others, predicts autoshaping and automaintenance, so it is uniquely positioned to predict autoshaped choice. The model also contemplates neural substrates of economic behavior in neuroeconomics, such as dopaminergic and hippocampal systems. A feedforward neural network architecture was designed to simulate a neuroanatomical differentiation between two environment-behavior relations X-R1 and Y-R2, [corrected] where R1 and R2 denote two different emitted responses (not unconditionally elicited by the reward). Networks with this architecture received a training protocol that simulated an autoshaped-choice procedure. Most networks simulated the phenomenon. Implications for behavioral economics and neuroeconomics, limitations, and the issue of model appraisal are discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

Autoshaping in adolescence enhances sign-tracking behavior in adulthood: Impact on ethanol consumption

PubMed Central

Anderson, Rachel I.; Spear, Linda P.

2011-01-01

Autoshaping refers to a procedure during which a cue repeatedly paired with a reward elicits a conditioned response directed at either the reward delivery location (“goal-tracking”) or the cue itself (“sign-tracking”). Individual differences in expression of sign-tracking behavior may be predictive of voluntary ethanol intake. The present study was designed to explore the development of differences in sign-tracking behavior in adolescent and adult male and female rats in an 8-day autoshaping procedure. Consistency of sign-tracking and goal-tracking across age was examined by retesting adolescents again in adulthood and comparing their adult data with animals tested only as adults to explore pre-exposure effects on adult responding. In order to assess the relationship between sign-tracking and ethanol intake, voluntary ethanol consumption was measured in an 8-day, 2-hr limited access drinking paradigm following the 8-day autoshaping procedure in adulthood. Animals tested as adolescents showed notably less sign-tracking behavior than animals tested as adults, and sign-tracking behavior was not correlated across age. Animals exposed to the autoshaping procedure as adolescents demonstrated greater sign-tracking behavior as adults when compared to control animals tested only in adulthood. When examining the relationship in adulthood between sign-tracking and ethanol intake, an increase in ethanol intake among sign-trackers was found only in animals pre-exposed to autoshaping as adolescents. Whether or not these results reflect an adolescent-specific experience effect is unclear without further work to determine whether comparable pre-exposure effects are seen if the initial autoshaping sessions are delayed into adulthood. PMID:21238477

Learning and Memory Enhancement by Neuropeptides

DTIC Science & Technology

1988-12-31

autoshaping task, in which rats learn to touch a lever to obtain fod.-,During the 6 months, three ppers have been published.~ .(44ý th 6 month , the paer...administration impairs autoshaped learning. Behavioral 1M Neurl Rio]y 51 (1989) 34-45. Also being prepared for publication is a study showing that...prepared concerns work showing that autoshaping is highly dependent upon the deprivation state of the animal: more fooddeprived ram learn faster. This is

Dorsomedial striatum lesions affect adjustment to reward uncertainty, but not to reward devaluation or omission.

PubMed

Torres, Carmen; Glueck, Amanda C; Conrad, Shannon E; Morón, Ignacio; Papini, Mauricio R

2016-09-22

The dorsomedial striatum (DMS) has been implicated in the acquisition of reward representations, a proposal leading to the hypothesis that it should play a role in situations involving reward loss. We report the results of an experiment in which the effects of DMS excitotoxic lesions were tested in consummatory successive negative contrast (reward devaluation), autoshaping training with partial vs. continuous reinforcement (reward uncertainty), and appetitive extinction (reward omission). Animals with DMS lesions exhibited reduced lever pressing responding, but enhanced goal entries, during partial reinforcement training in autoshaping. However, they showed normal negative contrast, acquisition under continuous reinforcement (CR), appetitive extinction, and response facilitation in early extinction trials. Open-field testing also indicated normal motor behavior. Thus, DMS lesions selectively affected the behavioral adjustment to a situation involving reward uncertainty, producing a behavioral reorganization according to which goal tracking (goal entries) became predominant at the expense of sign tracking (lever pressing). This pattern of results shows that the function of the DMS in situations involving reward loss is not general, but restricted to reward uncertainty. We suggest that a nonassociative, drive-related process induced by reward uncertainty requires normal output from DMS neurons. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

Autoshaping in adolescence enhances sign-tracking behavior in adulthood: impact on ethanol consumption.

PubMed

Anderson, Rachel I; Spear, Linda P

2011-04-01

Autoshaping refers to a procedure during which a cue repeatedly paired with a reward elicits a conditioned response directed at either the reward delivery location ("goal-tracking") or the cue itself ("sign- tracking"). Individual differences in expression of sign-tracking behavior may be predictive of voluntary ethanol intake. The present study was designed to explore the development of differences in sign-tracking behavior in adolescent and adult male and female rats in an 8-day autoshaping procedure. Consistency of sign-tracking and goal-tracking across age was examined by retesting adolescents again in adulthood and comparing their adult data with animals tested only as adults to explore pre-exposure effects on adult responding. In order to assess the relationship between sign-tracking and ethanol intake, voluntary ethanol consumption was measured in an 8-day, 2-hr limited access drinking paradigm following the 8-day autoshaping procedure in adulthood. Animals tested as adolescents showed notably less sign-tracking behavior than animals tested as adults, and sign-tracking behavior was not correlated across age. Animals exposed to the autoshaping procedure as adolescents demonstrated greater sign-tracking behavior as adults when compared to control animals tested only in adulthood. When examining the relationship in adulthood between sign-tracking and ethanol intake, an increase in ethanol intake among sign-trackers was found only in animals pre-exposed to autoshaping as adolescents. Whether or not these results reflect an adolescent-specific experience effect is unclear without further work to determine whether comparable pre-exposure effects are seen if the initial autoshaping sessions are delayed into adulthood. Copyright © 2011 Elsevier Inc. All rights reserved.

The influence of "preparedness" on autoshaping, schedule performance, and choice.

PubMed

Burns, J D; Malone, J C

1992-11-01

Two groups of experimentally naive pigeons were exposed to an autoshaping procedure in which the response key was mounted on the wall (the conventional location) or on the floor of the chamber. In two experiments, subjects readily responded to the wall key, but floor-key subjects required shaping. A subsequent experiment compared performance of wall- and floor-key groups on an ascending series of fixed-ratio schedule values, resistance to extinction, differential reinforcement of other behavior, and reversal of key assignment. Each experiment was followed by several sessions of fixed-ratio training; the performance of the wall- and floor-key groups was almost identical throughout. In the final experiment, a fixed-ratio requirement could be completed on either or both keys. Birds initially chose the key on which they had responded during the preceding (reversal of key assignment) experiment. However, within a few sessions both groups showed almost exclusive preference for the floor key. Preference for a key located on the floor may follow from the fact that pigeons are ground feeders and may thus be more "prepared" to peck the floor than to peck a wall. However, autoshaping, under the conditions prevailing here, occurred much more readily to the wall key, suggesting that pecking a vertical surface is more highly prepared. Difficulties in determining relative preparedness seem moot, however, given the lack of between-group differences in the intervening experiments. It is thus unlikely that schedule performances critically depend upon the specific operant response involved.

Performance of four different rat strains in the autoshaping, two-object discrimination, and swim maze tests of learning and memory.

PubMed

Andrews, J S; Jansen, J H; Linders, S; Princen, A; Broekkamp, C L

1995-04-01

The performance of four strains of rats commonly used in behavioural research was assessed in three different tests of learning and memory. The four strains included three outbred lines (Long-Evans, Sprague-Dawley, Wistar) and one inbred strain (S3). Learning and memory were tested using three different paradigms: autoshaping of a lever press, a two-object discrimination test, and performance in a two-island swim maze task. The pigmented strains showed better performance in the autoshaping procedure: the majority of the Long-Evans and the S3 rats acquired the response, and the majority of the Wistar and Sprague-Dawley failed to acquire the response in the set time. The albino strains were slightly better in the swim maze than the pigmented strains. There appeared to be a speed/accuracy trade-off in the strategy used to solve the task. This was also evident following treatment with the cholinergic-depleting agent hemicholinium-3. The performance of the Long-Evans rats was most affected by the treatment in terms of accuracy and the Wistar and Sprague-Dawleys in terms of speed. In the two-object discrimination test only the Long-Evans showed satisfactory performance and were able to discriminate a novel from a known object a short interval after initial exposure. These results show large task- and strain-dependent differences in performance in tests of learning and memory. Some of the performance variation may be due to emotional differences between the strains and may be alleviated by extra training. However, the response to pharmacological manipulation may require more careful evaluation.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoshaping as a psychophysical paradigm: Absolute visual sensitivity in the pigeon

PubMed Central

Passe, Dennis H.

1981-01-01

A classical conditioning procedure (autoshaping) was used to determine absolute visual threshold in the pigeon. This method provides the basis for a standardized visual psychophysical paradigm. PMID:16812228

Autoshaping Chicks with Heat Reinforcement: The Role of Stimulus-Reinforcer and Response-Reinforcer Relations

ERIC Educational Resources Information Center

Wasserman, Edward A.; And Others

1975-01-01

The present series of experiments attempted to analyze more fully the contributions of stimulus-reinforcer and response-reinforcer relations to autoshaping within a single conditioning situation. (Author)

Autoshaping and automaintenance: a neural-network approach.

PubMed

Burgos, José E

2007-07-01

This article presents an interpretation of autoshaping, and positive and negative automaintenance, based on a neural-network model. The model makes no distinction between operant and respondent learning mechanisms, and takes into account knowledge of hippocampal and dopaminergic systems. Four simulations were run, each one using an A-B-A design and four instances of feedfoward architectures. In A, networks received a positive contingency between inputs that simulated a conditioned stimulus (CS) and an input that simulated an unconditioned stimulus (US). Responding was simulated as an output activation that was neither elicited by nor required for the US. B was an omission-training procedure. Response directedness was defined as sensory feedback from responding, simulated as a dependence of other inputs on responding. In Simulation 1, the phenomena were simulated with a fully connected architecture and maximally intense response feedback. The other simulations used a partially connected architecture without competition between CS and response feedback. In Simulation 2, a maximally intense feedback resulted in substantial autoshaping and automaintenance. In Simulation 3, eliminating response feedback interfered substantially with autoshaping and automaintenance. In Simulation 4, intermediate autoshaping and automaintenance resulted from an intermediate response feedback. Implications for the operant-respondent distinction and the behavior-neuroscience relation are discussed.

Autoshaping and Automaintenance: A Neural-Network Approach

PubMed Central

Burgos, José E

2007-01-01

This article presents an interpretation of autoshaping, and positive and negative automaintenance, based on a neural-network model. The model makes no distinction between operant and respondent learning mechanisms, and takes into account knowledge of hippocampal and dopaminergic systems. Four simulations were run, each one using an A-B-A design and four instances of feedfoward architectures. In A, networks received a positive contingency between inputs that simulated a conditioned stimulus (CS) and an input that simulated an unconditioned stimulus (US). Responding was simulated as an output activation that was neither elicited by nor required for the US. B was an omission-training procedure. Response directedness was defined as sensory feedback from responding, simulated as a dependence of other inputs on responding. In Simulation 1, the phenomena were simulated with a fully connected architecture and maximally intense response feedback. The other simulations used a partially connected architecture without competition between CS and response feedback. In Simulation 2, a maximally intense feedback resulted in substantial autoshaping and automaintenance. In Simulation 3, eliminating response feedback interfered substantially with autoshaping and automaintenance. In Simulation 4, intermediate autoshaping and automaintenance resulted from an intermediate response feedback. Implications for the operant–respondent distinction and the behavior–neuroscience relation are discussed. PMID:17725055

Adrenalectomy eliminates the extinction spike in autoshaping with rats.

PubMed

Thomas, B L; Papini, M R

2001-03-01

Experiment 1, using rats, investigated the effect of adrenalectomy (ADX) on the invigoration of lever-contact performance that occurs in the autoshaping situation after a shift from acquisition to extinction (called the extinction spike). Groups of rats with ADX or sham operations were trained under spaced and massed conditions [average intertrial intervals (ITI) of either 15 or 90 s] for 10 sessions and then shifted to extinction. ADX did not affect acquisition training but it eliminated the extinction spike. Plasma corticosterone levels during acquisition were shown in Experiment 2 to be similar in rats trained under spaced or massed conditions. Adrenal participation in the emotional arousal induced by conditions of surprising nonreward (e.g., extinction) is discussed.

Autoshaping of key pecking in pigeons with negative reinforcement.

PubMed

Rachlin, H

1969-07-01

Pigeons exposed to gradually increasing intensities of pulsing electric shock pecked a key and thereby reduced the intensity of shock to zero for 2 min. Acquisition of key pecking was brought about through an autoshaping process in which periodic brief keylight presentations immediately preceded automatic reduction of the shock. On the occasions of such automatic reduction of shock preceding the first measured key peck, little or no orientation to the key was observed. Observations of pigeons with autoshaping of positive reinforcement also revealed little evidence of orientation toward the key.

Blocking, unblocking, and overexpectation in autoshaping with pigeons.

PubMed

Khallad, Y; Moore, J

1996-05-01

Three experiments used pigeons in an autoshaping procedure and a single-subject design to examine compound stimulus control in classical conditioning. Experiment 1 examined the blocking effect, and Experiment 2 examined the unblocking effect. In both experiments, response-independent food was first delivered intermittently in the presence of one distinctively colored houselight but not another. Then, conventional autoshaping trials were carried out in the presence of each houselight. In Experiment 1, the keylight readily elicited responding in the presence of the houselight that had been negatively correlated with food, but not in the presence of the houselight that had been positively correlated with food. In Experiment 2, the keylight readily elicited responding in the presence of the houselight positively correlated with food, but only when the amount of food used on the autoshaping trials was either greater or less than that previously delivered in the presence of the houselight. Experiment 3 examined the overexpectation effect. Conventional autoshaping trials were first carried out by presenting each of two keylights individually. Then, additional autoshaping trials were carried out by presenting the two keylights as a compound, with either the same amount of food or a greater amount of food per trial. Finally, the keylights were retested by again presenting them individually. The number of responses per trial elicited by the keylights decreased when the amount of food used in compound trials was the same as that used in individual trials. However, the number of responses per trial remained approximately the same when the amount of food used in compound trials was greater than that used in individual trials. Taken together, the results of the three experiments demonstrate (a) the generality of the blocking, unblocking, and overexpectation effects by virtue of their extension to appetitive unconditioned stimuli; (b) the suitability of pigeons as subjects and autoshaping as a procedure for studying classical conditioning; and (c) the appropriateness of single-subject designs.

Blocking, unblocking, and overexpectation in autoshaping with pigeons

PubMed Central

Khallad, Yacoub; Moore, Jay

1996-01-01

Three experiments used pigeons in an autoshaping procedure and a single-subject design to examine compound stimulus control in classical conditioning. Experiment 1 examined the blocking effect, and Experiment 2 examined the unblocking effect. In both experiments, response-independent food was first delivered intermittently in the presence of one distinctively colored houselight but not another. Then, conventional autoshaping trials were carried out in the presence of each houselight. In Experiment 1, the keylight readily elicited responding in the presence of the houselight that had been negatively correlated with food, but not in the presence of the houselight that had been positively correlated with food. In Experiment 2, the keylight readily elicited responding in the presence of the houselight positively correlated with food, but only when the amount of food used on the autoshaping trials was either greater or less than that previously delivered in the presence of the houselight. Experiment 3 examined the overexpectation effect. Conventional autoshaping trials were first carried out by presenting each of two keylights individually. Then, additional autoshaping trials were carried out by presenting the two keylights as a compound, with either the same amount of food or a greater amount of food per trial. Finally, the keylights were retested by again presenting them individually. The number of responses per trial elicited by the keylights decreased when the amount of food used in compound trials was the same as that used in individual trials. However, the number of responses per trial remained approximately the same when the amount of food used in compound trials was greater than that used in individual trials. Taken together, the results of the three experiments demonstrate (a) the generality of the blocking, unblocking, and overexpectation effects by virtue of their extension to appetitive unconditioned stimuli; (b) the suitability of pigeons as subjects and autoshaping as a procedure for studying classical conditioning; and (c) the appropriateness of single-subject designs. PMID:16812810

Panel-touch behavior of horses established by an autoshaping procedure.

PubMed

Miyashita, Y; Nakajima, S; Imada, H

1999-12-01

Panel-touch behavior of 3 geldings was successfully established by a response-termination type of autoshaping procedure. An omission or negative contingency introduced after the training of an animal, however, decreased the response rate to a near-zero level.

Autoshaping of key pecking in pigeons with negative reinforcement1

PubMed Central

Rachlin, Howard

1969-01-01

Pigeons exposed to gradually increasing intensities of pulsing electric shock pecked a key and thereby reduced the intensity of shock to zero for 2 min. Acquisition of key pecking was brought about through an autoshaping process in which periodic brief keylight presentations immediately preceded automatic reduction of the shock. On the occasions of such automatic reduction of shock preceding the first measured key peck, little or no orientation to the key was observed. Observations of pigeons with autoshaping of positive reinforcement also revealed little evidence of orientation toward the key. ImagesFig. 3.Fig. 4. PMID:16811371

Modelling individual differences in the form of Pavlovian conditioned approach responses: a dual learning systems approach with factored representations.

PubMed

Lesaint, Florian; Sigaud, Olivier; Flagel, Shelly B; Robinson, Terry E; Khamassi, Mehdi

2014-02-01

Reinforcement Learning has greatly influenced models of conditioning, providing powerful explanations of acquired behaviour and underlying physiological observations. However, in recent autoshaping experiments in rats, variation in the form of Pavlovian conditioned responses (CRs) and associated dopamine activity, have questioned the classical hypothesis that phasic dopamine activity corresponds to a reward prediction error-like signal arising from a classical Model-Free system, necessary for Pavlovian conditioning. Over the course of Pavlovian conditioning using food as the unconditioned stimulus (US), some rats (sign-trackers) come to approach and engage the conditioned stimulus (CS) itself - a lever - more and more avidly, whereas other rats (goal-trackers) learn to approach the location of food delivery upon CS presentation. Importantly, although both sign-trackers and goal-trackers learn the CS-US association equally well, only in sign-trackers does phasic dopamine activity show classical reward prediction error-like bursts. Furthermore, neither the acquisition nor the expression of a goal-tracking CR is dopamine-dependent. Here we present a computational model that can account for such individual variations. We show that a combination of a Model-Based system and a revised Model-Free system can account for the development of distinct CRs in rats. Moreover, we show that revising a classical Model-Free system to individually process stimuli by using factored representations can explain why classical dopaminergic patterns may be observed for some rats and not for others depending on the CR they develop. In addition, the model can account for other behavioural and pharmacological results obtained using the same, or similar, autoshaping procedures. Finally, the model makes it possible to draw a set of experimental predictions that may be verified in a modified experimental protocol. We suggest that further investigation of factored representations in computational neuroscience studies may be useful.

Modelling Individual Differences in the Form of Pavlovian Conditioned Approach Responses: A Dual Learning Systems Approach with Factored Representations

PubMed Central

Lesaint, Florian; Sigaud, Olivier; Flagel, Shelly B.; Robinson, Terry E.; Khamassi, Mehdi

2014-01-01

Reinforcement Learning has greatly influenced models of conditioning, providing powerful explanations of acquired behaviour and underlying physiological observations. However, in recent autoshaping experiments in rats, variation in the form of Pavlovian conditioned responses (CRs) and associated dopamine activity, have questioned the classical hypothesis that phasic dopamine activity corresponds to a reward prediction error-like signal arising from a classical Model-Free system, necessary for Pavlovian conditioning. Over the course of Pavlovian conditioning using food as the unconditioned stimulus (US), some rats (sign-trackers) come to approach and engage the conditioned stimulus (CS) itself – a lever – more and more avidly, whereas other rats (goal-trackers) learn to approach the location of food delivery upon CS presentation. Importantly, although both sign-trackers and goal-trackers learn the CS-US association equally well, only in sign-trackers does phasic dopamine activity show classical reward prediction error-like bursts. Furthermore, neither the acquisition nor the expression of a goal-tracking CR is dopamine-dependent. Here we present a computational model that can account for such individual variations. We show that a combination of a Model-Based system and a revised Model-Free system can account for the development of distinct CRs in rats. Moreover, we show that revising a classical Model-Free system to individually process stimuli by using factored representations can explain why classical dopaminergic patterns may be observed for some rats and not for others depending on the CR they develop. In addition, the model can account for other behavioural and pharmacological results obtained using the same, or similar, autoshaping procedures. Finally, the model makes it possible to draw a set of experimental predictions that may be verified in a modified experimental protocol. We suggest that further investigation of factored representations in computational neuroscience studies may be useful. PMID:24550719

Autoshaped head poking in the mouse: a quantitative analysis of the learning curve.

PubMed

Papachristos, Efstathios B; Gallistel, C R

2006-05-01

In autoshaping experiments, we quantified the acquisition of anticipatory head poking in individual mice, using an algorithm that finds changes in the slope of a cumulative record. In most mice, upward changes in the amount of anticipatory poking per trial were abrupt, and tended to occur at session boundaries, suggesting that the session is as significant a unit of experience as the trial. There were large individual differences in the latency to the onset of vigorous responding. "Asymptotic" performance was unstable; large, bidirectional, and relatively enduring changes were common. Given the characteristics of the individual learning curves, it is unlikely that physiologically meaningful estimates of rate of learning can be extracted from group-average learning curves.

Autoshaped Head Poking in the Mouse: A Quantitative Analysis of the Learning Curve

PubMed Central

Papachristos, Efstathios B; Gallistel, C.R

2006-01-01

In autoshaping experiments, we quantified the acquisition of anticipatory head poking in individual mice, using an algorithm that finds changes in the slope of a cumulative record. In most mice, upward changes in the amount of anticipatory poking per trial were abrupt, and tended to occur at session boundaries, suggesting that the session is as significant a unit of experience as the trial. There were large individual differences in the latency to the onset of vigorous responding. “Asymptotic” performance was unstable; large, bidirectional, and relatively enduring changes were common. Given the characteristics of the individual learning curves, it is unlikely that physiologically meaningful estimates of rate of learning can be extracted from group-average learning curves. PMID:16776053

Effects of Sarin on the Operant Behavior of Guinea Pigs

DTIC Science & Technology

2005-07-19

a after behavioral sessions had ended. The first collection time modified autoshaping procedure (concurrent variable-time was after the final saline...after behavioral sessions had ended. The first collection time modified autoshaping procedure (concurrent variable-time was after the final saline

Cognitive and Neural Sciences Division. 1988 Programs

DTIC Science & Technology

1988-08-01

the P.I. uses a delayed reinforcement autoshaping procedure which incorporates features of both classical and operant conditioning paradigms...Progress: The PT has completed initial dose-response study of effects of TMT on autoshaping and has submitted a paper that separates "non-specific

Autoshaping i.v. cocaine self-administration in rats: effects of nondrug alternative reinforcers on acquisition.

PubMed

Carroll, M E; Lac, S T

1993-01-01

The purpose of this experiment was to examine the effects of a nondrug alternative reinforcer and feeding conditions on the acquisition of cocaine self-administration. Rats were autoshaped to press a lever that resulted in a 0.2 mg/kg i.v. cocaine infusion. Responses on the lever were monitored during six consecutive autoshaping sessions that occurred each day. A retractable lever was inserted into the operant chamber on a random time 60 s schedule 10 times per session for six sessions that began each hour. Each day the six autoshaping sessions were followed by a 6-h cocaine self-administration session. During self-administration the lever remained extended, and each response on the lever resulted in a cocaine infusion (0.2 mg/kg). The criterion for acquisition of cocaine-reinforced behavior was met when there were 5 consecutive days during which the mean number of infusions during the 6-h self-administration session was at least 100. This procedure was repeated daily until the criterion was met or 30 days elapsed. The rats were also trained to respond on lick-operated automatic drinking devices that delivered 0.05 ml water or a glucose and saccharin solution (G + S) contingent upon each lick response. Five groups of 12-14 rats were compared. The first four groups constituted a 2 x 2 factorial design whereby either G + S or water was available in the home cage for 3 weeks before autoshaping began and G + S or water was available in the operant chamber during autoshaping. These groups were limited to 20 g food per day and all had free access to water.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Repeated Sublethal VX Exposure on Operant Time Estimation in Rats

DTIC Science & Technology

2007-08-01

1 week of food restriction, preliminary behavioral training ( autoshaping ) began. Apparatus Eight commercially available operant chambers for... Autoshaping was used to produce acquisition of lever pressing. Every 50 seconds (range = 10-90 s) on average, the cue light was illuminated and

Autoshaping of abnormal children.

PubMed

Deckner, C W; Wilcox, L M; Maisto, S A; Blanton, R L

1980-09-01

Three experimentally naive abnormal children were exposed to a terminal operant contingency, i.e., reinforcement was delivered only if the children pressed a panel during intervals when it was lighted. Despite the absence of both successive approximation and manual shaping, it was found that each child began to respond discriminatively within a small number of trials. These data replicated previous animal studies concerned with the phenomena of autoshaping and signal-controlled responding. It was also found, however, that one type of autoshaping, the classical conditioning procedure, had a powerful suppressive effect on the discriminative responding. An experimental analysis that consisted procedure, had a powerful suppressive effect on discriminative responding. An experimental analysis that consisted of intrasubject reversal an multiple baseline designs established the internal validity of the findings. The finding of rapid acquisition of signal-controlled responding obtained with the initial procedure is suggessted to have practical significance. The disruptive effects of the classical form of autoshaping are discussed in terms of negative behavioral contrast.

Effects of partial reinforcement and time between reinforced trials on terminal response rate in pigeon autoshaping.

PubMed

Gottlieb, Daniel A

2006-03-01

Partial reinforcement often leads to asymptotically higher rates of responding and number of trials with a response than does continuous reinforcement in pigeon autoshaping. However, comparisons typically involve a partial reinforcement schedule that differs from the continuous reinforcement schedule in both time between reinforced trials and probability of reinforcement. Two experiments examined the relative contributions of these two manipulations to asymptotic response rate. Results suggest that the greater responding previously seen with partial reinforcement is primarily due to differential probability of reinforcement and not differential time between reinforced trials. Further, once established, differences in responding are resistant to a change in stimulus and contingency. Secondary response theories of autoshaped responding (theories that posit additional response-augmenting or response-attenuating mechanisms specific to partial or continuous reinforcement) cannot fully accommodate the current body of data. It is suggested that researchers who study pigeon autoshaping train animals on a common task prior to training them under different conditions.

Rapid contextual conditioning in autoshaping.

PubMed

Balsam, P D; Schwartz, A L

1981-10-01

Two experiments are reported which investigate the speed of contextual conditioning in autoshaping. In both experiments, a procedure was employed in which ring doves were magazine trained in one context prior to the manipulation of background values in a second context. In Experiment 1, subjects were exposed to 4, 8, 64, 128, or 256 US-only presentations prior to autoshaping. Acquisition speed and maintained response measures were monotonically related to the number of pretraining trials. Subjects in Group 4 acquired the key-peck response fastest, and retardation was maximal within 64 pretraining trials. In Experiment 2, subjects given 20 pretraining trials were significantly more retarded than subjects given 2 pretraining trials, but only when pretraining and testing were conducted in the same context. Overall, the results of these experiments show that in autoshaping, contextual conditioning is very rapid; this demonstrates the plausibility of theoretical accounts of Pavlovian conditioning which assert that the development of the conditioned response depends on the associative values of both the CS and background stimuli.

Autoshaping a leverpress in rats with lateral, medial, or complete septal lesions.

PubMed

Poplawsky, A; Phillips, C L

1986-05-01

Rats with either control operations or lateral, medial, or complete septal lesions received 600 trials of leverpress training using an autoshaping procedure, i.e., food delivery followed a 10 s illuminated lever presentation, or occurred immediately after a leverpress. Rats with complete septal lesions acquired the leverpress faster than controls and had more food-tray entries per minute during the first 100 trials than the other groups. Rats with lateral or medial septal lesions had leverpress and food-tray entries equivalent to controls. The facilitation of autoshaping a leverpress may partially be explained by the general increase in motor reactivity to stimuli found following septal lesions.

Autoshaping of chlordiazepoxide drinking in non-deprived rats.

PubMed

Tomie, Arthur; Wong, Lauren E; Pohorecky, Larissa A

2005-02-28

Effects of autoshaping procedures (Paired versus Random) and sipper fluid [chlordiazepoxide (CDP) versus water] on sipper-directed drinking were evaluated in 32 male Long-Evans rats maintained with free access to food and water. For the Paired/CDP group (n = 16), autoshaping procedures consisted of the presentation of the CDP sipper conditioned stimulus (CS) followed by the response-independent presentation of the food unconditioned stimulus (US). The concentration of CDP in the sipper CS (0.05, 0.10, 0.15, 0.20, and 0.25 mg/ml CDP) was increased across sessions. The Paired/Water group (n = 8) received only water in the sipper CS. The Random/CDP group (n = 8) received the CDP sipper CS and food US randomly with respect to one another. The Paired/CDP group drank significantly more of the 0.20 mg/ml and 0.25 mg/ml CDP solutions than the Random/CDP control, and more fluid than the Paired/Water control group when the sipper CS for the Paired/CDP group contained the three highest concentrations of CDP. CS-Only extinction procedures reliably reduced sipper CS-directed drinking in the Paired/CDP and the Paired/Water groups, but not in the Random/CDP group. Data are consistent with the hypothesis that Pavlovian autoshaping procedures induce sipper CS-directed drinking of CDP in rats deprived of neither food nor fluid. Implications for the autoshaping model of drug abuse are discussed.

Learning and Memory Enhancement by Neuropeptides

DTIC Science & Technology

1989-06-30

organic solvents), or arising from disease states. We study learning in an autoshaping task, in which rats learn to touch a lever to obtain food. Dunng...R.B.. Allen. S1.. Aanonsen, L. and Sparber. SB. Naloxone adminimtration impairs autoshaped learning. Behavioral and Neural Biol, y51 (1989) 34-45

Autoshaping and Automaintenance: A Neural-Network Approach

ERIC Educational Resources Information Center

Burgos, Jose E.

2007-01-01

This article presents an interpretation of autoshaping, and positive and negative automaintenance, based on a neural-network model. The model makes no distinction between operant and respondent learning mechanisms, and takes into account knowledge of hippocampal and dopaminergic systems. Four simulations were run, each one using an "A-B-A" design…

Assessment of learning and memory using the autoshaping of operant responding in mice.

PubMed

Barrett, James E; Vanover, K E

2004-02-01

This unit describes the use of an automated procedure for developing an operant response ("autoshaping") in the mouse. The method has applications in the study of the acquisition of behavior (learning) as well as for the assessment of memory or retention of that task.

Two Attentional Models of Classical Conditioning: Variations in CS Effectiveness Revisited.

DTIC Science & Technology

1987-04-03

probability is in closer agreement with empirical expectations, tending to lie on a line with slope equal to 1. Experiments in pigeon autoshaping have shown...Gibbon, J., Farrell, L., Locurto, C.M., Duncan, H., & Terrace, H.S. (1980). Partial reinforcement in autoshaping with pigeons. Animal Learning and

Effects of selective excitotoxic lesions of the nucleus accumbens core, anterior cingulate cortex, and central nucleus of the amygdala on autoshaping performance in rats.

PubMed

Cardinal, Rudolf N; Parkinson, John A; Lachenal, Guillaume; Halkerston, Katherine M; Rudarakanchana, Nung; Hall, Jeremy; Morrison, Caroline H; Howes, Simon R; Robbins, Trevor W; Everitt, Barry J

2002-08-01

The nucleus accumbens core (AcbC), anterior cingulate cortex (ACC), and central nucleus of the amygdala (CeA) are required for normal acquisition of tasks based on stimulus-reward associations. However, it is not known whether they are involved purely in the learning process or are required for behavioral expression of a learned response. Rats were trained preoperatively on a Pavlovian autoshaping task in which pairing a visual conditioned stimulus (CS+) with food causes subjects to approach the CS+ while not approaching an unpaired stimulus (CS-). Subjects then received lesions of the AcbC, ACC, or CeA before being retested. AcbC lesions severely impaired performance; lesioned subjects approached the CS+ significantly less often than controls, failing to discriminate between the CS+ and CS-. ACC lesions also impaired performance but did not abolish discrimination entirely. CeA lesions had no effect on performance. Thus, the CeA is required for learning, but not expression, of a conditioned approach response, implying that it makes a specific contribution to the learning of stimulus-reward associations.

Social opportunity and ethanol drinking in rats.

PubMed

Tomie, Arthur; Burger, Kelly M; Di Poce, Jason; Pohorecky, Larissa A

2004-11-01

Two experiments were designed to evaluate the effects of pairings of ethanol sipper conditioned stimulus (CS) with social opportunity unconditioned stimulus (US) on ethanol sipper CS-directed drinking in rats. In both experiments, rats were deprived of neither food nor water, and initiation of drinking of unsweetened 3% ethanol was evaluated, as were the effects of increasing the concentration of unsweetened ethanol (3-10%) across sessions. In Experiment 1, Group Paired (n=8) received 35 trials per session wherein the ethanol sipper CS was presented for 10 s immediately prior to 15 s of social opportunity US. All rats initiated sipper CS-directed drinking of 3% ethanol. Increasing the concentration of ethanol in the sipper CS [(3%, 4%, 6%, 8%, 10% (vol./vol.)] across sessions induced escalation of daily g/kg ethanol intake. To evaluate the hypothesis that the drinking in Group Paired was due to autoshaping, Experiment 2 included a pseudoconditioning control that received sipper CS and social opportunity US randomly with respect to one another. All rats in Group Paired (n=6) and in Group Random (n=6) initiated sipper CS-directed drinking of 3% ethanol and daily mean g/kg ethanol intake in the two groups was comparable. Also comparable was daily g/kg ethanol intake, which increased for both groups with the availability of higher concentrations of ethanol in the sipper CS, up to a maximum of approximately 0.8 g/kg ethanol intake of 10% ethanol. Results indicate that random presentations of ethanol sipper CS and social opportunity US induced reliable initiation and escalation of ethanol intake, and close temporally contiguous presentations of CS and US did not induce still additional ethanol intake. This may indicate that autoshaping CR performance is not induced by these procedures, or that high levels of ethanol intake induced by factors related to pseudoconditioning produces a ceiling effect. Implications for ethanol drinking in humans are discussed.

Context Blocking in Rat Autoshaping: Sign-Tracking versus Goal-Tracking

ERIC Educational Resources Information Center

Costa, Daniel S. J.; Boakes, Robert A.

2009-01-01

Prior experience of unsignaled food can interfere with subsequent acquisition by birds of autoshaped key-pecking at a signal light. This has been understood to indicate that unsignaled food results in context conditioning, which blocks subsequent learning about the keylight-food relationship. In the present experiment with rats lever insertion as…

Summation in Autoshaping with Compounds Formed by the Rapid Alternation of Elements

ERIC Educational Resources Information Center

Gomez-Sancho, Luis E.; Fernandez-Serra, Francisco; Arias, M. Francisca

2013-01-01

Summation is the usual result in composition procedures with excitatory stimuli. However, summation is difficult to obtain in autoshaping with pigeons. The problems with this preparation have been related to the stimuli used: combinations of intramodal conditioned stimuli (CSs). During the perceptual processing of this type of stimuli, some mutual…

A Service Life Analysis of Coast Guard C-130 Aircraft

DTIC Science & Technology

2003-03-01

the drawing tool bar. If you feel more comfortable with estimating at points, you could also use AutoShapes to identify your estimate at a particular...you feel more comfortable with estimating at points, you could also use AutoShapes to identify your estimate at a particular year. If you prefer to

Stimulus- and response-reinforcer contingencies in autoshaping, operant, classical, and omission training procedures in rats.

PubMed

Atnip, G W

1977-07-01

Separate groups of rats received 500 trials of lever-press training under autoshaping (food delivery followed 10-second lever presentations, or occurred immediately following a response); operant conditioning (responding was necessary for food delivery); and classical conditioning (food followed lever presentations regardless of responding). Each group then received 500 trials on an omission procedure in which food was omitted on trials with a response. Another group received 1000 trials on the omission procedure, and a fifth group, random control, received 1000 uncorrelated presentations of lever and food. The autoshaping, operant, and classical groups reached high response levels by the end of initial training. Acquisition was fastest in the autoshaping group. Responding remained consistently low in the control group. The omission group responded at a level between the control group and the other three groups. During omission training, responding in these three groups declined to the omission-group level. During omission training, the rats continued contacting the lever frequently after lever pressing had declined. Response maintenance under omission training seems not to require topographic similarity between the response and reinforcer-elicited consummatory behaviors.

Stimulus- and response-reinforcer contingencies in autoshaping, operant, classical, and omission training procedures in rats

PubMed Central

Atnip, Gilbert W.

1977-01-01

Separate groups of rats received 500 trials of lever-press training under autoshaping (food delivery followed 10-second lever presentations, or occurred immediately following a response); operant conditioning (responding was necessary for food delivery); and classical conditioning (food followed lever presentations regardless of responding). Each group then received 500 trials on an omission procedure in which food was omitted on trials with a response. Another group received 1000 trials on the omission procedure, and a fifth group, random control, received 1000 uncorrelated presentations of lever and food. The autoshaping, operant, and classical groups reached high response levels by the end of initial training. Acquisition was fastest in the autoshaping group. Responding remained consistently low in the control group. The omission group responded at a level between the control group and the other three groups. During omission training, responding in these three groups declined to the omission-group level. During omission training, the rats continued contacting the lever frequently after lever pressing had declined. Response maintenance under omission training seems not to require topographic similarity between the response and reinforcer-elicited consummatory behaviors. PMID:16812014

Rats socially-reared and full fed learned an autoshaping task, showing less levels of fear-like behaviour than fasted or singly-reared rats.

PubMed

Molina-Hernández, Miguel; Téllez-Alcántara, N Patricia

2004-07-01

During the learning of instrumental tasks, rats are usually fasted to increase reinforced learning. However, fasting produces several undesirable side effects. The aim of this study was to test the hypothesis that control rats, i.e. full-fed and group-reared rats, will learn an autoshaping task to the same level as fasted or singly-reared rats. The interaction between fasting and single-rearing of rats was also tested. Results showed that control rats and fasted rats acquired the autoshaping task similarly, independently of rearing condition or gender. However, fasted or singly-reared rats produced fear-like behaviour, since male rats group-reared and fasted (85% body/wt, P <0.05), male rats singly-reared (full fed, P <0.05; 12 h fasted, P <0.05; 85% body/wt, P <0.05), female rats group-reared (12 h fasted, P <0.05; 85% body/wt, P <0.05) and female rats singly reared (full fed, P <0.05; 12 h fasted, P <0.05; 85% body/wt, P <0.05) displayed reduced amounts of time exploring the open arms of the elevated plus-maze. In conclusion, control rats learned the autoshaping task to the same level as fasted or singly-reared rats. However, fasting or single-rearing produced fear-like behaviour. Thus, the training of control rats in autoshaping tasks may be an option that improves animal welfare.

Acquisition with partial and continuous reinforcement in pigeon autoshaping.

PubMed

Gottlieb, Daniel A

2004-08-01

Contemporary time accumulation models make the unique prediction that acquisition of a conditioned response will be equally rapid with partial and continuous reinforcement, if the time between conditioned stimuli is held constant. To investigate this, acquisition of conditioned responding was examined in pigeon autoshaping under conditions of 100% and 25% reinforcement, holding intertrial interval constant. Contrary to what was predicted, evidence for slowed acquisition in partially reinforced animals was observed with several response measures. However, asymptotic performance was superior with 25% reinforcement. A switching of reinforcement contingencies after initial acquisition did not immediately affect responding. After further sessions, partial reinforcement augmented responding, whereas continuous reinforcement did not, irrespective of an animal's reinforcement history. Subsequent training with a novel stimulus maintained the response patterns. These acquisition results generally support associative, rather than time accumulation, accounts of conditioning.

Autoshaped Head Poking in the Mouse: A Quantitative Analysis of the Learning Curve

ERIC Educational Resources Information Center

Papachristos, Efstathios B.; Gallistel, C. R.

2006-01-01

In autoshaping experiments, we quantified the acquisition of anticipatory head poking in individual mice, using an algorithm that finds changes in the slope of a cumulative record. In most mice, upward changes in the amount of anticipatory poking per trial were abrupt, and tended to occur at session boundaries, suggesting that the session is as…

The associative relation underlying autoshaping in the pigeon1

PubMed Central

Woodruff, Guy; Williams, D. R.

1976-01-01

Fifteen pigeons were exposed to either response-independent or response-dependent schedules of water reinforcement, whereby water was injected directly into the unrestrained pigeons' mandibles. Key-contact responses were released by a lighted key correlated with water, but not by a lighted key uncorrelated with water. A negative response-reinforcer contingency suppressed autoshaped key-contact responses, resulting in responding directed away from the lighted key. In all pigeons, water injected directly into the mandibles elicited a consummatory fixed-action pattern of “mumbling” and swallowing. The lighted key correlated with water released a broader set of both appetitive and consummatory responses: approach to the lighted key, “bowing”, “rooting”, “mumbling”, and swallowing. Key-contact responses were “rooting” and “mumbling” motions of the beak on the surface of the key. Views of autoshaping based on stimulus substitution or stimulus surrogation do not fully explain the origin of autoshaped responses not previously elicited by the reinforcer. The present findings are consonant with views of conditioning that emphasize the large degree of biological pre-organization in conditioned response patterns, and the importance of associative factors in the control of such patterns. PMID:16811924

Autoshaping with common and distinctive stimulus elements, compact and dispersed arrays.

PubMed

Sperling, S E; Perkins, M E

1979-05-01

Four groups of pigeons were trained with a standard autoshaping procedure in which a brief fixed-duration interval always followed by a grain delivery alternated with a longer variable-duration interval never associated with grain delivery. One of two stimuli was always presented during each interval. One of them contained three black dots and a black star on a green background; the other contained four black dots on a green background. The four elements of each stimulus were arranged in a more compact array for two groups and in a more dispersed array for the other two groups. Which of the two stimuli preceded grain delivery was counterbalanced within each pair of groups. The speed of occurrence of the first autoshaped peck was not affected by whether the stimulus containing the distinctive star element preceded grain delivery, but autoshaping was faster when the stimulus arrays were compact than when they were dispersed. During 560 response-independent training trials that followed the first autoshaped peck, this pattern reversed; both discriminative control over responding and the relative frequency of pecking the stimulus that preceded grain delivery were greater for the two groups where this stimulus contained the discriminative element than for the two groups where it contained only common elements. During subsequent testing with stimuli containing only a single element each, the distinctive feature was responded to proportionately more often by the two groups for which it had been an element of the stimulus preceding grain delivery than by the two groups for which it had been an element of the stimulus complex that never was associated with grain delivery. These data add further support to the hypothesis that the initial occurrence of autoshaped responding and its subsequent maintenance are not affected by the same variables. They also suggest that automaintenance is as sensitive as response-dependent training to the presence or absence of a distinctive stimulus element among several common elements and that this sensitivity appears to be independent of the specific method used for presenting the stimuli during automaintenance.

Autoshaping with common and distinctive stimulus elements, compact and dispersed arrays1

PubMed Central

Sperling, Sally E.; Perkins, Mark E.

1979-01-01

Four groups of pigeons were trained with a standard autoshaping procedure in which a brief fixed-duration interval always followed by a grain delivery alternated with a longer variable-duration interval never associated with grain delivery. One of two stimuli was always presented during each interval. One of them contained three black dots and a black star on a green background; the other contained four black dots on a green background. The four elements of each stimulus were arranged in a more compact array for two groups and in a more dispersed array for the other two groups. Which of the two stimuli preceded grain delivery was counterbalanced within each pair of groups. The speed of occurrence of the first autoshaped peck was not affected by whether the stimulus containing the distinctive star element preceded grain delivery, but autoshaping was faster when the stimulus arrays were compact than when they were dispersed. During 560 response-independent training trials that followed the first autoshaped peck, this pattern reversed; both discriminative control over responding and the relative frequency of pecking the stimulus that preceded grain delivery were greater for the two groups where this stimulus contained the discriminative element than for the two groups where it contained only common elements. During subsequent testing with stimuli containing only a single element each, the distinctive feature was responded to proportionately more often by the two groups for which it had been an element of the stimulus preceding grain delivery than by the two groups for which it had been an element of the stimulus complex that never was associated with grain delivery. These data add further support to the hypothesis that the initial occurrence of autoshaped responding and its subsequent maintenance are not affected by the same variables. They also suggest that automaintenance is as sensitive as response-dependent training to the presence or absence of a distinctive stimulus element among several common elements and that this sensitivity appears to be independent of the specific method used for presenting the stimuli during automaintenance. PMID:16812139

Dissociable contributions of the orbitofrontal and infralimbic cortex to pavlovian autoshaping and discrimination reversal learning: further evidence for the functional heterogeneity of the rodent frontal cortex.

PubMed

Chudasama, Y; Robbins, Trevor W

2003-09-24

To examine possible heterogeneity of function within the ventral regions of the rodent frontal cortex, the present study compared the effects of excitotoxic lesions of the orbitofrontal cortex (OFC) and the infralimbic cortex (ILC) on pavlovian autoshaping and discrimination reversal learning. During the pavlovian autoshaping task, in which rats learn to approach a stimulus predictive of reward [conditional stimulus (CS+)], only the OFC group failed to acquire discriminated approach but was unimpaired when preoperatively trained. In the visual discrimination learning and reversal task, rats were initially required to discriminate a stimulus positively associated with reward. There was no effect of either OFC or ILC lesions on discrimination learning. When the stimulus-reward contingencies were reversed, both groups of animals committed more errors, but only the OFC-lesioned animals were unable to suppress the previously rewarded stimulus-reward association, committing more "stimulus perseverative" errors. In contrast, the ILC group showed a pattern of errors that was more attributable to "learning" than perseveration. These findings suggest two types of dissociation between the effects of OFC and ILC lesions: (1) OFC lesions impaired the learning processes implicated in pavlovian autoshaping but not instrumental simultaneous discrimination learning, whereas ILC lesions were unimpaired at autoshaping and their reversal learning deficit did not reflect perseveration, and (2) OFC lesions induced perseverative responding in reversal learning but did not disinhibit responses to pavlovian CS-. In contrast, the ILC lesion had no effect on response inhibitory control in either of these settings. The findings are discussed in the context of dissociable executive functions in ventral sectors of the rat prefrontal cortex.

Autoshaping of ethanol drinking in rats: effects of ethanol concentration and trial spacing.

PubMed

Tomie, Arthur; Wong, Karlvin; Apor, Khristine; Patterson-Buckendahl, Patricia; Pohorecky, Larissa A

2003-11-01

In two studies, we evaluated the effects of ethanol concentration and trial spacing on Pavlovian autoshaping of ethanol drinking in rats. In these studies, the brief insertion of an ethanol sipper conditioned stimulus (CS) was followed by the response-independent presentation of food unconditioned stimulus (US), inducing sipper CS-directed drinking conditioned responses (CRs) in all rats. In Experiment 1, the ethanol concentration in the sipper CS [0%-16% volume/volume (vol./vol.), in increments of 1%] was systematically increased within subjects across autoshaping sessions. Groups of rats received sipper CS-food US pairings (Paired/Ethanol), a CS-US random procedure (Random/Ethanol), or water sipper CS paired with food US (Paired/Water). In Experiment 2, saccharin-fading procedures were used to initiate, in the Ethanol group, drinking of 6% (vol./vol.) ethanol in 0.1% saccharin or, in the Water group, drinking of tap water in 0.1% saccharin. After elimination of saccharin, and across days, the duration of access to the sipper CS during each autoshaping trial was increased (5, 10, 12.5, 15, 17.5, and 20 s), and subsequently, across days, the duration of the mean intertrial interval (ITI) was increased (60, 90, 120, and 150 s). In Experiment 1, Paired/Ethanol and Random/Ethanol groups showed higher intake of ethanol, in terms of grams per kilogram of body weight, at higher ethanol concentrations, with more ethanol intake recorded in the Paired/Ethanol group. In Experiment 2, the Ethanol group drank more than was consumed by the Water group, and, for both groups, fluid intake increased with longer ITIs. Results support the suggestion that autoshaping contributes to sipper CS-directed ethanol drinking.

The learning curve: Implications of a quantitative analysis

PubMed Central

Gallistel, Charles R.; Fairhurst, Stephen; Balsam, Peter

2004-01-01

The negatively accelerated, gradually increasing learning curve is an artifact of group averaging in several commonly used basic learning paradigms (pigeon autoshaping, delay- and trace-eye-blink conditioning in the rabbit and rat, autoshaped hopper entry in the rat, plus maze performance in the rat, and water maze performance in the mouse). The learning curves for individual subjects show an abrupt, often step-like increase from the untrained level of responding to the level seen in the well trained subject. The rise is at least as abrupt as that commonly seen in psychometric functions in stimulus detection experiments. It may indicate that the appearance of conditioned behavior is mediated by an evidence-based decision process, as in stimulus detection experiments. If the appearance of conditioned behavior is taken instead to reflect the increase in an underlying associative strength, then a negligible portion of the function relating associative strength to amount of experience is behaviorally visible. Consequently, rate of learning cannot be estimated from the group-average curve; the best measure is latency to the onset of responding, determined for each subject individually. PMID:15331782

The learning curve: implications of a quantitative analysis.

PubMed

Gallistel, Charles R; Fairhurst, Stephen; Balsam, Peter

2004-09-07

The negatively accelerated, gradually increasing learning curve is an artifact of group averaging in several commonly used basic learning paradigms (pigeon autoshaping, delay- and trace-eye-blink conditioning in the rabbit and rat, autoshaped hopper entry in the rat, plus maze performance in the rat, and water maze performance in the mouse). The learning curves for individual subjects show an abrupt, often step-like increase from the untrained level of responding to the level seen in the well trained subject. The rise is at least as abrupt as that commonly seen in psychometric functions in stimulus detection experiments. It may indicate that the appearance of conditioned behavior is mediated by an evidence-based decision process, as in stimulus detection experiments. If the appearance of conditioned behavior is taken instead to reflect the increase in an underlying associative strength, then a negligible portion of the function relating associative strength to amount of experience is behaviorally visible. Consequently, rate of learning cannot be estimated from the group-average curve; the best measure is latency to the onset of responding, determined for each subject individually.

Choline acetyltransferase and TrkA expression, as well as the improvement in cognition produced by E2 and P4 in ovariectomized rats, are blocked by ICI 182 780 and RU486.

PubMed

Espinosa-Raya, Judith; Cruz-Raya, Ulises; López-Martínez, Margarita; Picazo, Ofir

2018-01-09

Treatment with 17-β estradiol and progesterone improves the performance of ovariectomized rats in an autoshaping learning task, representing cognitive improvement. To test whether this is attributable to genomic mechanisms, the antiestrogen ICI 182 780 or antiprogesterone RU486 was injected into ovariectomized animals primed previously with estrogen or progesterone, respectively. Compared with the vehicle control, each hormone administered alone produced an elevated expression of choline acetyltransferase and TrkA, along with an improvement in performance on the behavioral test. E2+ICI reverted the increase in these two proteins. However, RU alone elicited higher ChAT expression. With this exception, there was a clear linear regression between the number of conditioned responses and the level of ChAT and TrkA in the basal forebrain. The results suggest that TrkA may be more important than ChAT for regulating autoshaping learning tasks, and that genomic mechanisms in the basal forebrain could possibly underlie hormonal improvement of cognition.

Controls for and constraints on auto-shaping

PubMed Central

Bilbrey, John; Winokur, Stephen

1973-01-01

Auto-shaping the pigeon's key-peck response was examined as a respondent conditioning procedure with the use of Rescorla's truly-random control procedure. In the first experiment, pigeons received presentations of brief light on the response key and brief presentations of food where the light and the food were independently presented. All birds failed to key peck after many light and food presentations, but explicit pairing of the light and food rapidly conditioned pecking to the light. Experiment 2 showed that even when an independent light/food presentation schedule was reduced to variable-time 30 sec, additional naive birds would not key peck and only one bird pecked when the schedules were variable-time 15 sec. A third experiment examined an explicit-unpairing control procedure, where the light and food were not only presented on independent schedules but were also separated by a minimum time, and found that auto-shaping did not occur. A fourth experiment investigated a number of control procedures and found them ineffective. A fifth experiment investigated the effects of a physical separation of the locus of the response key and the food dispenser, and a sixth experiment investigated using a tone in place of the light. It was concluded that pecking is generated by auto-shaping procedures only when an intermittently presented keylight is regularly paired with food. PMID:16811710

Choice as a dependent measure in autoshaping: sensitivity to frequency and duration of food presentation.

PubMed Central

Picker, M; Poling, A

1982-01-01

Previous investigations have shown that rate, latency, and percentage of trials with at least one response are somewhat insensitive measures of the strength of autoshaped responding. In the present studies, these measures were contrasted with the allocation of responding during simultaneous choice tests, a measure of response strength frequently used in operant paradigms. In two experiments, nine pigeons were exposed to a forward pairing autoshaping procedure. Training sessions consisted of the successive presentation of three stimuli, each followed by food on either 100%, 50%, or 0% of the trials. Choice testing involved the simultaneous presentation of the three stimuli. In Experiment I, all pigeons consistently directed their initial choice responses and the majority of subsequent responses to the stimulus always followed by food, despite the fact that during training sessions the response rates of most birds were highest in the presence of the stimulus followed by food on 50% of the trials. In Experiment II, rate, latency, and percentage of trials with at least one response did not change appreciably as a function of duration of feeder presentations. However, choice responding was lawfully affected by duration of feeder presentations. These data suggest that choice is perhaps a more sensitive measure of the strength of autoshaped responding than other, more commonly employed, indices. PMID:7097152

Autoshaping and automaintenance of a key-press response in squirrel monkeys

PubMed Central

Gamzu, Elkan; Schwam, Elias

1974-01-01

Following exposure for a minimum of 500 to 600 trials, three of four naive squirrel monkeys eventually pressed a response key, illumination of which always preceded delivery of a food pellet. Three other naive monkeys did not press the key when the pellets were delivered randomly with respect to key illumination. Despite some similarities to autoshaping using pigeons, the data indicate many points of difference when squirrel monkeys are used as subjects. Although key-food pairings were shown to be important in the acquisition of the key-press response, they were ineffective in maintaining the response when either a negative response-reinforcer dependency was introduced, or when there was no scheduled response-reinforcer dependency (fixed trial). Not all demonstrations of autoshaping can be considered to be under the control of those processes that are primarily responsible for the phenomena obtained in pigeons. PMID:16811749

Autoshaping and automaintenance of a key-press response in squirrel monkeys.

PubMed

Gamzu, E; Schwam, E

1974-03-01

Following exposure for a minimum of 500 to 600 trials, three of four naive squirrel monkeys eventually pressed a response key, illumination of which always preceded delivery of a food pellet. Three other naive monkeys did not press the key when the pellets were delivered randomly with respect to key illumination. Despite some similarities to autoshaping using pigeons, the data indicate many points of difference when squirrel monkeys are used as subjects. Although key-food pairings were shown to be important in the acquisition of the key-press response, they were ineffective in maintaining the response when either a negative response-reinforcer dependency was introduced, or when there was no scheduled response-reinforcer dependency (fixed trial). Not all demonstrations of autoshaping can be considered to be under the control of those processes that are primarily responsible for the phenomena obtained in pigeons.

Acquisition session length modulates consolidation effects produced by 5-HT2C ligands in a mouse autoshaping-operant procedure.

PubMed

Walker, Ellen A; Foley, John J

2010-03-01

Although the neurotransmitter, 5-hydroxytryptamine (serotonin, 5-HT), has been implicated as a mediator of learning and memory, the specific role of 5-HT receptors in rodents requires further delineation. In this study, 5-HT2C receptor ligands of varying relative intrinsic efficacies were tested in a mouse learning and memory model called autoshaping-operant. On day 1, mice were placed in experimental chambers and presented with a tone on a variable interval schedule. The tone remained on for 6 s or until a nose-poke response occurred to produce a dipper with Ensure solution. Mice were then injected with saline, MK212 (full agonist), m-chlorophenylpiperazine (partial agonist), mianserin, and SB206 553 (inverse agonists), and methysergide and (+)-2-bromo lysergic acid diethylamide (+)-hydrogen tartrate (neutral antagonists). Each compound was injected after either 1 or 2-h acquisition sessions on day 1 to investigate the role of acquisition session length on consolidation. Day 1 injection of the 5-HT2C inverse agonist mianserin produced greater retrieval impairments of the autoshaped operant response on day 2 than any other agent tested. Furthermore, decreasing the length of the acquisition session to 1h significantly increased the difficulty of the autoshaping task further modulating the consolidation effects produced by the 5-HT2C ligands tested.

Autoshaping as a function of prior food presentations1

PubMed Central

Downing, Kevin; Neuringer, Allen

1976-01-01

Young chickens were given 1, 10, 100, or 1000 presentations of grain in a hopper. Subsequently, the key was illuminated before each presentation of grain to study autoshaping of the key-peck response. The number of keylight-grain pairings before a bird first pecked the lighted key was found to be a U-shaped function of the number of prior food-only presentations, with pecks occurring significantly sooner after 100 food-only trials than after any of the other values. Two of five chicks at the 100-trial value pecked on the first illumination of the key. Experiment II showed further that when a series of food-only trials (no keylight) preceded keylight-only trials (no food) 30% of the chicks pecked the illuminated key. Experiment III extended the generality of first-trial pecking to pigeons. After preliminary training with food-only, two of five pigeons pecked on the first illumination of a key. The results suggest a close relationship between autoshaping and pseudo-conditioning. PMID:16811961

Differential autoshaping to common and distinctive elements of positive and negative discriminative stimuli.

PubMed

Wasserman, E A; Anderson, P A

1974-11-01

The learning by hungry pigeons of a discrimination between two successively presented compound visual stimuli was investigated using a two-key autoshaping procedure. Common and distinctive stimulus elements were simultaneously presented on separate keys and either followed by food delivery, S+, or not, S-. The subjects acquired both between-trial and within-trial discriminations. On S+ trials, pigeons pecked the distinctive stimulus more than the common stimulus; before responding ceased on S- trials, they pecked the common stimulus more than the distinctive one. Mastery of the within-display discrimination during S+ trials preceded mastery of the between-trials discrimination. These findings extend the Jenkins-Sainsbury analysis of discriminations based upon a single distinguishing feature to discriminations in which common and distinctive elements are associated with both the positive and negative discriminative stimuli. The similarity of these findings to other effects found in autoshaping-approach to signals that forecast reinforcement and withdrawal from signals that forecast nonreinforcement-is also discussed.

Autoshaping as a function of prior food presentations.

PubMed

Downing, K; Neuringer, A

1976-11-01

Young chickens were given 1, 10, 100, or 1000 presentations of grain in a hopper. Subsequently, the key was illuminated before each presentation of grain to study autoshaping of the key-peck response. The number of keylight-grain pairings before a bird first pecked the lighted key was found to be a U-shaped function of the number of prior food-only presentations, with pecks occurring significantly sooner after 100 food-only trials than after any of the other values. Two of five chicks at the 100-trial value pecked on the first illumination of the key. Experiment II showed further that when a series of food-only trials (no keylight) preceded keylight-only trials (no food) 30% of the chicks pecked the illuminated key. Experiment III extended the generality of first-trial pecking to pigeons. After preliminary training with food-only, two of five pigeons pecked on the first illumination of a key. The results suggest a close relationship between autoshaping and pseudo-conditioning.

Contrast and autoshaping in multiple schedules varying reinforcer rate and duration.

PubMed

Hamilton, B E; Silberberg, A

1978-07-01

Thirteen master pigeons were exposed to multiple schedules in which reinforcement frequency (Experiment I) or duration (Experiment II) was varied. In Phases 1 and 3 of Experiment I, the values of the first and second components' random-interval schedules were 33 and 99 seconds, respectively. In Phase 2, these values were 99 seconds for both components. In Experiment II, a random-interval 33-second schedule was associated with each component. During Phases 1 and 3, the first and second components had hopper durations of 7.5 and 2.5 seconds respectively. During Phase 2, both components' hopper durations were 2.5 seconds. In each experiment, positive contrast obtained for about half the master subjects. The rest showed a rate increase in both components (positive induction). Each master subject's key colors and reinforcers were synchronously presented on a response-independent basis to a yoked control. Richer component key-pecking occurred during each experiment's Phases 1 and 3 among half these subjects. However, none responded during the contrast condition (unchanged component of each experiment's Phase 2). From this it is inferred that autoshaping did not contribute to the contrast and induction findings among master birds. Little evidence of local contrast (highest rate at beginning of richer component) was found in any subject. These data show that (a) contrast can occur independently from autoshaping, (b) contrast assays during equal-valued components may produce induction, (c) local contrast in multiple schedules often does not occur, and (d) differential hopper durations can produce autoshaping and contrast.

Autoradiographic study of serotonin transporter during memory formation.

PubMed

Tellez, Ruth; Rocha, Luisa; Castillo, Carlos; Meneses, Alfredo

2010-09-01

Serotonin transporter (SERT) has been associated with drugs of abuse like d-methamphetamine (METH). METH is well known to produce effects on the monoamine systems but it is unclear how METH affects SERT and memory. Here the effects of METH and the serotonin reuptake inhibitor fluoxetine (FLX) on autoshaping and novel object recognition (NOR) were investigated. Notably, both memory tasks recruit different behavioral, neural and cognitive demand. In autoshaping task a dose-response curve for METH was determined. METH (1.0mg/kg) impaired short-term memory (STM; lasting less of 90min) in NOR and impaired both STM and long-term memory (LTM; lasting 24 and 48h) in autoshaping, indicating that METH had long-lasting effects in the latter task. A comparative autoradiography study of the relationship between the binding pattern of SERT in autoshaping new untrained vs. trained treated (METH, FLX, or both) animals was made. Considering that hemispheric dominance is important for LTM, hence right vs. left hemisphere of the brain was compared. Results showed that trained animals decreased cortical SERT binding relative to untrained ones. In untrained and trained treated animals with the amnesic dose (1.0mg/kg) of METH SERT binding in several areas including hippocampus and cortex decreased, more remarkably in the trained animals. In contrast, FLX improved memory, increased SERT binding, prevented the METH amnesic effect and re-established the SERT binding. In general, memory and amnesia seemed to make SERT more vulnerable to drugs effects. Copyright 2010 Elsevier B.V. All rights reserved.

Role of 5-HT5A receptors in the consolidation of memory.

PubMed

Gonzalez, Roberto; Chávez-Pascacio, Karla; Meneses, Alfredo

2013-09-01

5-HT5 receptor occurs in brain areas implicated in learning and memory. Hence, the effects (0.01-3.0 mg/kg) of SB-6995516 (a 5-HT5A receptor antagonist) in the associative learning task of autoshaping were studied. The results showed that post-training injection of SB-699551 decreased conditioned responses (CR) during short-term (STM; 1.5h; at 0.1mg/kg) and long-term memory (LTM; 24 h; at 3.0 mg/kg) relative to the vehicle animals. Moreover, considering that there are no selective 5-HT5A receptor agonists, next, diverse doses of the serotonin precursor l-tryptophan were studied during STM and LTM, showing that l-tryptophan (5-100mg/kg) facilitated performance, particularly at 50mg/kg. In interactions experiments, l-tryptophan (50 mg/kg) attenuated the impairment effect induced by SB-699551 (either 0.3 or 3.0 mg/kg). All together this evidence suggests that the blockade of 5-HT5A receptor appear to be able to impair STM and LTM (24 h), while its stimulation might facilitate it. Of course further investigation is necessary, meanly with selective 5-HT5A compounds are necessary. Copyright © 2013 Elsevier B.V. All rights reserved.

The attribution of incentive salience to Pavlovian alcohol cues: a shift from goal-tracking to sign-tracking.

PubMed

Srey, Chandra S; Maddux, Jean-Marie N; Chaudhri, Nadia

2015-01-01

Environmental stimuli that are reliably paired with alcohol may acquire incentive salience, a property that can operate in the use and abuse of alcohol. Here we investigated the incentive salience of Pavlovian alcohol cues using a preclinical animal model. Male, Long-Evans rats (Harlan) with unrestricted access to food and water were acclimated to drinking 15% ethanol (v/v) in their home-cages. Rats then received Pavlovian autoshaping training in which the 10 s presentation of a retractable lever served as the conditioned stimulus (CS) and 15% ethanol served as the unconditioned stimulus (US) (0.2 ml/CS; 12 CS presentations/session; 27 sessions). Next, in an operant test of conditioned reinforcement, nose pokes into an active aperture delivered presentations of the lever-CS, whereas nose pokes into an inactive aperture had no consequences. Across initial autoshaping sessions, goal-tracking behavior, as measured by entries into the fluid port where ethanol was delivered, developed rapidly. However, with extended training goal-tracking diminished, and sign-tracking responses, as measured by lever-CS activations, emerged. Control rats that received explicitly unpaired CS and US presentations did not show goal-tracking or sign-tracking responses. In the test for conditioned reinforcement, rats with CS-US pairings during autoshaping training made more active relative to inactive nose pokes, whereas rats in the unpaired control group did not. Moreover, active nose pokes were positively correlated with sign-tracking behavior during autoshaping. Extended training may produce a shift in the learned properties of Pavlovian alcohol cues, such that after initially predicting alcohol availability they acquire robust incentive salience.

Contrast and autoshaping in multiple schedules varying reinforcer rate and duration

PubMed Central

Hamilton, Bruce E.; Silberberg, Alan

1978-01-01

Thirteen master pigeons were exposed to multiple schedules in which reinforcement frequency (Experiment I) or duration (Experiment II) was varied. In Phases 1 and 3 of Experiment I, the values of the first and second components' random-interval schedules were 33 and 99 seconds, respectively. In Phase 2, these values were 99 seconds for both components. In Experiment II, a random-interval 33-second schedule was associated with each component. During Phases 1 and 3, the first and second components had hopper durations of 7.5 and 2.5 seconds respectively. During Phase 2, both components' hopper durations were 2.5 seconds. In each experiment, positive contrast obtained for about half the master subjects. The rest showed a rate increase in both components (positive induction). Each master subject's key colors and reinforcers were synchronously presented on a response-independent basis to a yoked control. Richer component key-pecking occurred during each experiment's Phases 1 and 3 among half these subjects. However, none responded during the contrast condition (unchanged component of each experiment's Phase 2). From this it is inferred that autoshaping did not contribute to the contrast and induction findings among master birds. Little evidence of local contrast (highest rate at beginning of richer component) was found in any subject. These data show that (a) contrast can occur independently from autoshaping, (b) contrast assays during equal-valued components may produce induction, (c) local contrast in multiple schedules often does not occur, and (d) differential hopper durations can produce autoshaping and contrast. PMID:16812081

Effects of the 5-HT7 receptor antagonists SB-269970 and DR 4004 in autoshaping Pavlovian/instrumental learning task.

PubMed

Meneses, Alfredo

2004-12-06

There is an important debate regarding the functional role of the 5-HT(1A) and 5-HT(7) receptor in memory systems. Hence, the objective of this paper is to investigate the function of serotonin (5-hydroxytryptamine, 5-HT) in memory consolidation, utilising an autoshaping Pavlovian/instrumental learning test. Specific antagonists at 5-HT(1A) (WAY 100635) and 5-HT(7) (SB-269970 or DR 4004) receptors administered i.p. or s.c.) after training, significantly decreased the improvement of performance produced by the 5-HT(1A/7) agonist 8-OH-DPAT to levels lower than controls'. These same antagonists attenuated the decreased level of performance produced by mCPP, although they decrease the performance levels after p-chloroamphetamine (PCA) lesion of the 5-HT system, which has no effect on its own on the conditioned response. Moreover, SB-269970 or DR 4004 reversed amnesia induced by scopolamine and dizocilpine. These data confirm a role for 5-HT(1A) and 5-HT(7) receptors in memory formation and support the hypothesis that serotonergic, cholinergic, and glutamatergic systems interact in cognitively impaired animals. These findings support a potential role for both 5-HT(1A) and 5-HT(7) receptors in the pathophysiology and/or treatment of schizophrenia, cognitive deficits and the mechanism of action of atypical antipsychotic drugs.

Species-specific response-topography of chickens' and pigeons' water-induced autoshaped responding.

PubMed

Ploog, Bertram O

2014-07-01

Four pigeons and eight chickens received autoshaping training where a keylight (conditioned stimulus) signaled response-independent deliveries of water (unconditioned stimulus). Pigeons drink while keeping their beaks submerged in water and moving their beaks to create suction ("mumbling"), whereas chickens drink by trapping a small amount of water in their mouths and then lifting their heads so the water trickles down. This experiment tested whether these and other species-specific differences in drinking and related behaviors of pigeons and chickens would be reflected in the form of conditioned (autoshaped) responding. Touchscreens and videotapes were used for data recording. Results showed that chickens moved their heads more than pigeons when drinking (unconditioned response). The birds also differed in conditioned responding in the presence of the keylight: Pigeons produced more keyswitch closures and mumbled at the keylight more than chickens whereas chickens scratched more than pigeons. In conclusion, with this unique comparative method that employed identical contingencies and comparable deprivation levels, species-specific differences in unconditioned responses and, more importantly, differences in their corresponding conditioned responses were observed. Copyright © 2014 Elsevier B.V. All rights reserved.

Acquisition and extinction in autoshaping.

PubMed

Kakade, Sham; Dayan, Peter

2002-07-01

C. R. Gallistel and J. Gibbon (2000) presented quantitative data on the speed with which animals acquire behavioral responses during autoshaping, together with a statistical model of learning intended to account for them. Although this model captures the form of the dependencies among critical variables, its detailed predictions are substantially at variance with the data. In the present article, further key data on the speed of acquisition are used to motivate an alternative model of learning, in which animals can be interpreted as paying different amounts of attention to stimuli according to estimates of their differential reliabilities as predictors.

The attribution of incentive salience to Pavlovian alcohol cues: a shift from goal-tracking to sign-tracking

PubMed Central

Srey, Chandra S.; Maddux, Jean-Marie N.; Chaudhri, Nadia

2015-01-01

Environmental stimuli that are reliably paired with alcohol may acquire incentive salience, a property that can operate in the use and abuse of alcohol. Here we investigated the incentive salience of Pavlovian alcohol cues using a preclinical animal model. Male, Long-Evans rats (Harlan) with unrestricted access to food and water were acclimated to drinking 15% ethanol (v/v) in their home-cages. Rats then received Pavlovian autoshaping training in which the 10 s presentation of a retractable lever served as the conditioned stimulus (CS) and 15% ethanol served as the unconditioned stimulus (US) (0.2 ml/CS; 12 CS presentations/session; 27 sessions). Next, in an operant test of conditioned reinforcement, nose pokes into an active aperture delivered presentations of the lever-CS, whereas nose pokes into an inactive aperture had no consequences. Across initial autoshaping sessions, goal-tracking behavior, as measured by entries into the fluid port where ethanol was delivered, developed rapidly. However, with extended training goal-tracking diminished, and sign-tracking responses, as measured by lever-CS activations, emerged. Control rats that received explicitly unpaired CS and US presentations did not show goal-tracking or sign-tracking responses. In the test for conditioned reinforcement, rats with CS-US pairings during autoshaping training made more active relative to inactive nose pokes, whereas rats in the unpaired control group did not. Moreover, active nose pokes were positively correlated with sign-tracking behavior during autoshaping. Extended training may produce a shift in the learned properties of Pavlovian alcohol cues, such that after initially predicting alcohol availability they acquire robust incentive salience. PMID:25784867

Disconnection of basolateral amygdala and insular cortex disrupts conditioned approach in Pavlovian lever autoshaping.

PubMed

Nasser, Helen M; Lafferty, Danielle S; Lesser, Ellen N; Bacharach, Sam Z; Calu, Donna J

2018-01-01

Previously established individual differences in appetitive approach and devaluation sensitivity observed in goal- and sign-trackers may be attributed to differences in the acquisition, modification, or use of associative information in basolateral amygdala (BLA) pathways. Here, we sought to determine the extent to which communication of associative information between BLA and anterior portions of insular cortex (IC) supports ongoing Pavlovian conditioned approach behaviors in sign- and goal-tracking rats, in the absence of manipulations to outcome value. We hypothesized that the BLA mediates goal-, but not sign- tracking approach through interactions with the IC, a brain region involved in supporting flexible behavior. We first trained rats in Pavlovian lever autoshaping to determine their sign- or goal-tracking tendency. During alternating test sessions, we gave unilateral intracranial injections of vehicle or a cocktail of gamma-aminobutyric acid (GABA) receptor agonists, baclofen and muscimol, unilaterally into the BLA and contralaterally or ipsilaterally into the IC prior to reinforced lever autoshaping sessions. Consistent with our hypothesis we found that contralateral inactivation of BLA and IC increased the latency to approach the food cup and decreased the number of food cup contacts in goal-trackers. While contralateral inactivation of BLA and IC did not affect the total number of lever contacts in sign-trackers, this manipulation increased the latency to approach the lever. Ipsilateral inactivation of BLA and IC did not impact approach behaviors in Pavlovian lever autoshaping. These findings, contrary to our hypothesis, suggest that communication between BLA and IC maintains a representation of initially learned appetitive associations that commonly support the initiation of Pavlovian conditioned approach behavior regardless of whether it is directed at the cue or the location of reward delivery. Copyright © 2017 Elsevier Inc. All rights reserved.

The "where is it?" reflex: autoshaping the orienting response.

PubMed

Buzsáki, G

1982-05-01

The goal of this review is to compare two divergent lines of research on signal-centered behavior: the orienting reflex (OR) and autoshaping. A review of conditioning experiments in animals and humans suggests that the novelty hypothesis of the OR is no longer tenable. Only stimuli that represent biological "relevance" elicit ORs. A stimulus may be relevant a priori (i.e., unconditioned) or as a result of conditioning. Exposure to a conditioned stimulus (CS) that predicts a positive reinforcer causes the animal to orient to it throughout conditioning. Within the CS-US interval, the initial CS-directed orienting response is followed by US-directed tendencies. Experimental evidence is shown that the development and maintenance of the conditioned OR occur in a similar fashion both in response-independent (classical) and response-dependent (instrumental) paradigms. It is proposed that the conditioned OR and the signal-directed autoshaped response are identical. Signals predicting aversive events repel the subject from the source of the CS. It is suggested that the function of the CS is not only to signal the probability of US occurrence, but also to serve as a spatial cue to guide the animal in the environment.

The hippocampus and appetitive Pavlovian conditioning: effects of excitotoxic hippocampal lesions on conditioned locomotor activity and autoshaping.

PubMed

Ito, Rutsuko; Everitt, Barry J; Robbins, Trevor W

2005-01-01

The hippocampus (HPC) is known to be critically involved in the formation of associations between contextual/spatial stimuli and behaviorally significant events, playing a pivotal role in learning and memory. However, increasing evidence indicates that the HPC is also essential for more basic motivational processes. The amygdala, by contrast, is important for learning about the motivational significance of discrete cues. This study investigated the effects of excitotoxic lesions of the rat HPC and the basolateral amygdala (BLA) on the acquisition of a number of appetitive behaviors known to be dependent on the formation of Pavlovian associations between a reward (food) and discrete stimuli or contexts: (1) conditioned/anticipatory locomotor activity to food delivered in a specific context and (2) autoshaping, where rats learn to show conditioned discriminated approach to a discrete visual CS+. While BLA lesions had minimal effects on conditioned locomotor activity, hippocampal lesions facilitated the development of both conditioned activity to food and autoshaping behavior, suggesting that hippocampal lesions may have increased the incentive motivational properties of food and associated conditioned stimuli, consistent with the hypothesis that the HPC is involved in inhibitory processes in appetitive conditioning. (c) 2005 Wiley-Liss, Inc.

Topographical variations in behavior during autoshaping, automaintenance, and omission training

PubMed Central

Eldridge, Gloria D.; Pear, Joseph J.

1987-01-01

Three pigeons were exposed to an autoshaping and automaintenance procedure while a computer-controlled tracking system continuously recorded the position of the bird's head as it moved freely in the experimental chamber. Although only 2 birds pecked the key during the conditional stimulus (red keylight), all 3 birds exhibited stable patterns of approaching the conditional stimulus and withdrawing from the intertrial stimulus (white keylight). Subsequent exposure to an omission procedure, in which pecks on the red key cancelled the presentation of food upon the termination of the red keylight, greatly reduced key pecking, but approaching and pecking in the vicinity of the conditional stimulus were maintained at high levels. When the omission contingency was removed key pecking increased. During all phases the birds withdrew from the area of the white key and engaged in repetitive back-and-forth or circuiting movements during this intertrial stimulus. The data document (a) the strong control the conditional stimulus in autoshaping and automaintenance exerts over approach to the key and pecking motions whether or not the conditional stimulus elicits key pecking at a high level; and (b) withdrawal from the vicinity of the key and the occurrence of stereotypic behavior during the intertrial interval. PMID:16812484

The "where is it?" reflex: autoshaping the orienting response.

PubMed Central

Buzsáki, G

1982-01-01

The goal of this review is to compare two divergent lines of research on signal-centered behavior: the orienting reflex (OR) and autoshaping. A review of conditioning experiments in animals and humans suggests that the novelty hypothesis of the OR is no longer tenable. Only stimuli that represent biological "relevance" elicit ORs. A stimulus may be relevant a priori (i.e., unconditioned) or as a result of conditioning. Exposure to a conditioned stimulus (CS) that predicts a positive reinforcer causes the animal to orient to it throughout conditioning. Within the CS-US interval, the initial CS-directed orienting response is followed by US-directed tendencies. Experimental evidence is shown that the development and maintenance of the conditioned OR occur in a similar fashion both in response-independent (classical) and response-dependent (instrumental) paradigms. It is proposed that the conditioned OR and the signal-directed autoshaped response are identical. Signals predicting aversive events repel the subject from the source of the CS. It is suggested that the function of the CS is not only to signal the probability of US occurrence, but also to serve as a spatial cue to guide the animal in the environment. PMID:7097153

Topographical variations in behavior during autoshaping, automaintenance, and omission training.

PubMed

Eldridge, G D; Pear, J J

1987-05-01

Three pigeons were exposed to an autoshaping and automaintenance procedure while a computer-controlled tracking system continuously recorded the position of the bird's head as it moved freely in the experimental chamber. Although only 2 birds pecked the key during the conditional stimulus (red keylight), all 3 birds exhibited stable patterns of approaching the conditional stimulus and withdrawing from the intertrial stimulus (white keylight). Subsequent exposure to an omission procedure, in which pecks on the red key cancelled the presentation of food upon the termination of the red keylight, greatly reduced key pecking, but approaching and pecking in the vicinity of the conditional stimulus were maintained at high levels. When the omission contingency was removed key pecking increased. During all phases the birds withdrew from the area of the white key and engaged in repetitive back-and-forth or circuiting movements during this intertrial stimulus. The data document (a) the strong control the conditional stimulus in autoshaping and automaintenance exerts over approach to the key and pecking motions whether or not the conditional stimulus elicits key pecking at a high level; and (b) withdrawal from the vicinity of the key and the occurrence of stereotypic behavior during the intertrial interval.

[Autoshaping of a button-push response and eye movement in human subjects].

PubMed

Kimura, H; Fukui, I; Inaki, K

1990-12-01

Two experiments were conducted with human subjects to investigate the similarities and differences between animal and human behaviors under autoshaping procedures. In these experiments, light served as CS, and display on TV served as US. Whether the pushing button response or gazing response to CS could be obtained in human subjects under Pavlovian conditioning procedure was examined. In Experiment 1, uninstructed naive subjects were placed in a room containing a push-button and a TV display. Within the experimental sessions, the push-button was lit for 8 s as CS, and then paired with the display of a soft pornographic program on TV for 10 s. The result indicated that the modeling of pushing button promoted the increase of response probability among the subjects. The trials conducted after the rest period indicated an increase of response probability. In Experiment 2, a 4 cm square translucent panel was lit for 20 s as CS, and then paired with the display of a computer graphic picture on TV for 8 s as US. Some subjects started gazing at the CS for several seconds. These results indicated that some subjects could acquire the gazing response under the autoshaping procedure.

Ovariectomy increases the age-induced hyperphosphorylation of Tau at hippocampal CA1.

PubMed

Picazo, O; Espinosa-Raya, J; Briones-Aranda, A; Cerbón, M

2016-11-01

One of the main hallmarks of Alzheimer's disease includes the neurofibrillary tangles formation produced by hyperphosphorylation of the Tau protein, whose expression is putatively regulated by the ovarian hormones estradiol and progesterone. Hippocampus is a brain region that participates in many functions related to learning and memory; in addition, it is abundant in both estradiol and progesterone receptors. In this study, we explore the expression of Tau hyperphosphorylation at hippocampus and the performance of rats in an autoshaping learning task at 5, 10 and 15 months after the ovaries removal. In these animals, ovariectomy was performed at 3 months of age. These data were compared with those derived from intact rats at 8, 13 and 18 months old. A clear decrease in the number of conditioned responses of both intact and ovariectomized rats in the autoshaping learning task was observed. The interaction of both factors confirms that, in this test, learning varies depending on aging and the presence or absence of ovaries. A progressive increase in hippocampal Tau phosphorylation at Ser-396 was observed in either intact or ovariectomized rats. Interestingly, an interaction between the analyzed factors shows that such hyperphosphorylation was potentiated by the absence of ovaries. These results emphasize the importance of aging and the lack of ovarian hormones for an associative learning test and for the expression of one of the most important hallmarks of Alzheimer's disease.

Summation in autoshaping is affected by the similarity of the visual stimuli to the stimulation they replace.

PubMed

Pearce, John M; Redhead, Edward S; George, David N

2002-04-01

Pigeons received autoshaping with 2 stimuli, A and B, presented in adjacent regions on a television screen. Conditioning with each stimulus was therefore accompanied by stimulation that was displaced from the screen whenever the other stimulus was presented. Test trials with AB revealed stronger responding if this displaced stimulation was similar to, rather than different from, A and B. For a further experiment the training just described included trials with A and B accompanied by an additional, similar, stimulus. Responding during test trials with AB was stronger if the additional trials signaled the presence rather than the absence of food. The results are explained with a configural theory of conditioning.

Temporal specificity of extinction in autoshaping.

PubMed

Drew, Michael R; Yang, Cynthia; Ohyama, Tatsuya; Balsam, Peter D

2004-07-01

Three experiments investigated the effects of varying the conditioned stimulus (CS) duration between training and extinction. Ring doves (Streptopelia risoria) were autoshaped on a fixed CS-unconditioned stimulus (US) interval and extinguished with CS presentations that were longer, shorter, or the same as the training duration. During a subsequent test session, the training CS duration was reintroduced. Results suggest that the cessation of responding during an extinction session is controlled by generalization of excitation between the training and extinction CSs and by the number of nonreinforced CS presentations. Transfer of extinction to the training CS is controlled by the similarity between the extinction and training CSs. Extinction learning is temporally specific. (c) 2004 APA, all rights reserved

Role of the ventrolateral orbital cortex and medial prefrontal cortex in incentive downshift situations.

PubMed

Ortega, Leonardo A; Glueck, Amanda C; Uhelski, Megan; Fuchs, Perry N; Papini, Mauricio R

2013-05-01

The present research evaluated the role of two prefrontal cortex areas, the ventrolateral orbital cortex (VLO) and the medial prefrontal cortex (mPFC), on two situations involving incentive downshifts, consummatory successive negative contrast (cSNC) with sucrose solutions and Pavlovian autoshaping following continuous vs. partial reinforcement with food pellets. Animals received electrolytic lesions and then were tested on cSNC, autoshaping, open-field activity, and sucrose sensitivity. Lesions of the VLO reduced suppression of consummatory behavior after the incentive downshift, but only during the first downshift trial, and also eliminated the enhancement of anticipatory behavior during partial reinforcement, relative to continuous reinforcement, in autoshaping. There was no evidence of specific effects of mPFC lesions on incentive downshifts. Open-field activity was also reduced by VLO lesions, but only in the central area, whereas mPFC lesions had no observable effects on activity. Animals with mPFC lesions exhibited decreased consumption of the lowest sucrose concentration, whereas no effects were observed in animals with VLO lesions. These results suggest that the VLO may exert nonassociative (i.e., motivational, emotional) influences on behavior in situations involving incentive downshifts. No clear role on incentive downshift was revealed by mPFC lesions. Copyright © 2013 Elsevier B.V. All rights reserved.

Operant Conditioning in Honey Bees (Apis mellifera L.): The Cap Pushing Response.

PubMed

Abramson, Charles I; Dinges, Christopher W; Wells, Harrington

2016-01-01

The honey bee has been an important model organism for studying learning and memory. More recently, the honey bee has become a valuable model to understand perception and cognition. However, the techniques used to explore psychological phenomena in honey bees have been limited to only a few primary methodologies such as the proboscis extension reflex, sting extension reflex, and free flying target discrimination-tasks. Methods to explore operant conditioning in bees and other invertebrates are not as varied as with vertebrates. This may be due to the availability of a suitable response requirement. In this manuscript we offer a new method to explore operant conditioning in honey bees: the cap pushing response (CPR). We used the CPR to test for difference in learning curves between novel auto-shaping and more traditional explicit-shaping. The CPR protocol requires bees to exhibit a novel behavior by pushing a cap to uncover a food source. Using the CPR protocol we tested the effects of both explicit-shaping and auto-shaping techniques on operant conditioning. The goodness of fit and lack of fit of these data to the Rescorla-Wagner learning-curve model, widely used in classical conditioning studies, was tested. The model fit well to both control and explicit-shaping results, but only for a limited number of trials. Learning ceased rather than continuing to asymptotically approach the physiological most accurate possible. Rate of learning differed between shaped and control bee treatments. Learning rate was about 3 times faster for shaped bees, but for all measures of proficiency control and shaped bees reached the same level. Auto-shaped bees showed one-trial learning rather than the asymptotic approach to a maximal efficiency. However, in terms of return-time, the auto-shaped bees' learning did not carry over to the covered-well test treatments.

Operant Conditioning in Honey Bees (Apis mellifera L.): The Cap Pushing Response

PubMed Central

Abramson, Charles I.; Dinges, Christopher W.; Wells, Harrington

2016-01-01

The honey bee has been an important model organism for studying learning and memory. More recently, the honey bee has become a valuable model to understand perception and cognition. However, the techniques used to explore psychological phenomena in honey bees have been limited to only a few primary methodologies such as the proboscis extension reflex, sting extension reflex, and free flying target discrimination-tasks. Methods to explore operant conditioning in bees and other invertebrates are not as varied as with vertebrates. This may be due to the availability of a suitable response requirement. In this manuscript we offer a new method to explore operant conditioning in honey bees: the cap pushing response (CPR). We used the CPR to test for difference in learning curves between novel auto-shaping and more traditional explicit-shaping. The CPR protocol requires bees to exhibit a novel behavior by pushing a cap to uncover a food source. Using the CPR protocol we tested the effects of both explicit-shaping and auto-shaping techniques on operant conditioning. The goodness of fit and lack of fit of these data to the Rescorla-Wagner learning-curve model, widely used in classical conditioning studies, was tested. The model fit well to both control and explicit-shaping results, but only for a limited number of trials. Learning ceased rather than continuing to asymptotically approach the physiological most accurate possible. Rate of learning differed between shaped and control bee treatments. Learning rate was about 3 times faster for shaped bees, but for all measures of proficiency control and shaped bees reached the same level. Auto-shaped bees showed one-trial learning rather than the asymptotic approach to a maximal efficiency. However, in terms of return-time, the auto-shaped bees’ learning did not carry over to the covered-well test treatments. PMID:27626797

Stimulus selection and tracking during urination: autoshaping directed behavior with toilet targets.

PubMed Central

Siegel, R K

1977-01-01

A simple procedure is described for investigating stimuli selected as targets during urination in the commode. Ten normal males preferred a floating target that could be tracked to a series of stationary targets. This technique was used to bring misdirected urinations in a severely retarded male under rapid stimulus control of a floating target in the commode. The float stimulus was also evaluated with nine institionalized, moderately retarded males and results indicated rapid autoshaping of directed urination without the use of verbal instructions or conventional toilet training. The technique can be applied in training children to control misdirected urinations in institution for the retarded, in psychiatric wards with regressed populations, and in certain male school dormitories. PMID:885828

Autoshaping in micrencephalic rats.

PubMed

Goldstein, L H; Oakley, D A

1989-06-01

An autoshaping procedure in which the illumination of a lever was predictive of food reinforcement was used to compare learning in rats with micrencephaly induced by irradiation on the 16th day of gestation and in sham-irradiated controls. Both groups showed equivalent levels of lever-directed activity, and the micrencephalic animals differentiated as well as the control animals between the predictive lever and a nonpredictive lever. The micrencephalic animals were able to redistribute their lever-directed activity when the significance of the levers was reversed and did so more readily than the control animals. Results support the claim that association learning survives either traumatic or developmental neocortical damage and have implications for remedial procedures following both head injury and developmental cerebral pathology in humans.

Stimulus selection and tracking during urination: autoshaping directed behavior with toilet targets.

PubMed

Siegel, R K

1977-01-01

A simple procedure is described for investigating stimuli selected as targets during urination in the commode. Ten normal males preferred a floating target that could be tracked to a series of stationary targets. This technique was used to bring misdirected urinations in a severely retarded male under rapid stimulus control of a floating target in the commode. The float stimulus was also evaluated with nine institionalized, moderately retarded males and results indicated rapid autoshaping of directed urination without the use of verbal instructions or conventional toilet training. The technique can be applied in training children to control misdirected urinations in institution for the retarded, in psychiatric wards with regressed populations, and in certain male school dormitories.

Autoshaping the pigeon's gape response: acquisition and topography as a function of reinforcer type and magnitude.

PubMed Central

Allan, R W; Zeigler, H P

1994-01-01

The pigeon's key-pecking response is experimentally dissociable into transport (head movement) and gape (jaw movement) components. During conditioning of the key-pecking response, both components come under the control of the conditioned stimulus. To study the acquisition of gape conditioned responses and to clarify the contribution of unconditioned stimulus (reinforcer) variables to the form of the response, gape and key-contact responses were recorded during an autoshaping procedure and reinforcer properties were systematically varied. One group of 8 pigeons was food deprived and subgroups of 2 birds each were exposed to four different pellet sizes as reinforcers, each reinforcer signaled by a keylight conditioned stimulus. A second group was water deprived and received water reinforcers paired with the conditioned stimulus. Water- or food-deprived control groups received appropriate water or food reinforcers that were randomly delivered with respect to the keylight stimulus. Acquisition of the conditioned gape response frequently preceded key-contact responses, and gape conditioned responses were generally elicited at higher rates than were key contacts. The form of the conditioned gape was similar to, but not identical with, the form of the unconditioned gape. The gape component is a critical topographical feature of the conditioned key peck, a sensitive measure of conditioning during autoshaping, and an important source of the observed similarities in the form of conditioned and consummatory responses. PMID:7964365

Autoshaping induces ethanol drinking in nondeprived rats: evidence of long-term retention but no induction of ethanol preference.

PubMed

Tomie, Arthur; Kuo, Teresa; Apor, Khristine R; Salomon, Kimberly E; Pohorecky, Larissa A

2004-04-01

The effects of autoshaping procedures (paired vs. random) and sipper fluid (ethanol vs. water) on sipper-directed drinking were evaluated in male Long-Evans rats maintained with free access to food and water. For the paired/ethanol group (n=16), autoshaping procedures consisted of presenting the ethanol sipper (containing 0% to 28% unsweetened ethanol) conditioned stimulus (CS) followed by the response-independent presentation of food unconditioned stimulus (US). The random/ethanol group (n=8) received the sipper CS and food US randomly with respect to one another. The paired/water group (n=8) received only water in the sipper CS. The paired/ethanol group showed higher grams per kilogram ethanol intake than the random/ethanol group did at ethanol concentrations of 8% to 28%. The paired/ethanol group showed higher sipper CS-directed milliliter fluid consumption than the paired/water group did at ethanol concentrations of 1% to 6%, and 15%, 16%, 18%, and 20%. Following a 42-day retention interval, the paired/ethanol group showed superior retention of CS-directed drinking of 18% ethanol, relative to the random/ethanol group, and superior retention of CS-directed milliliter fluid drinking relative to the paired/water group. When tested for home cage ethanol preference using limited access two-bottle (28% ethanol vs. water) procedures, the paired/ethanol and random/ethanol groups did not differ on any drinking measures.

Autoshaping the pigeon's gape response: acquisition and topography as a function of reinforcer type and magnitude.

PubMed

Allan, R W; Zeigler, H P

1994-09-01

The pigeon's key-pecking response is experimentally dissociable into transport (head movement) and gape (jaw movement) components. During conditioning of the key-pecking response, both components come under the control of the conditioned stimulus. To study the acquisition of gape conditioned responses and to clarify the contribution of unconditioned stimulus (reinforcer) variables to the form of the response, gape and key-contact responses were recorded during an autoshaping procedure and reinforcer properties were systematically varied. One group of 8 pigeons was food deprived and subgroups of 2 birds each were exposed to four different pellet sizes as reinforcers, each reinforcer signaled by a keylight conditioned stimulus. A second group was water deprived and received water reinforcers paired with the conditioned stimulus. Water- or food-deprived control groups received appropriate water or food reinforcers that were randomly delivered with respect to the keylight stimulus. Acquisition of the conditioned gape response frequently preceded key-contact responses, and gape conditioned responses were generally elicited at higher rates than were key contacts. The form of the conditioned gape was similar to, but not identical with, the form of the unconditioned gape. The gape component is a critical topographical feature of the conditioned key peck, a sensitive measure of conditioning during autoshaping, and an important source of the observed similarities in the form of conditioned and consummatory responses.

A Pharmacological Analysis of an Associative Learning Task: 5-HT1 to 5-HT7 Receptor Subtypes Function on a Pavlovian/Instrumental Autoshaped Memory

PubMed Central

Meneses, Alfredo

2003-01-01

Recent studies using both invertebrates and mammals have revealed that endogenous serotonin (5-hydroxytryptamine [5-HT]) modulates plasticity processes, including learning and memory. However, little is currently known about the mechanisms, loci, or time window of the actions of 5-HT. The aim of this review is to discuss some recent results on the effects of systemic administration of selective agonists and antagonists of 5-HT on associative learning in a Pavlovian/instrumental autoshaping (P/I-A) task in rats. The results indicate that pharmacological manipulation of 5-HT1-7 receptors or 5-HT reuptake sites might modulate memory consolidation, which is consistent with the emerging notion that 5-HT plays a key role in memory formation. PMID:14557609

Autoshaping in the rat: conditioned licking response to a stimulus that signals sucrose reinforcement.

PubMed

Reilly, Steve; Grutzmacher, Richard P.

2002-07-31

The present experiments were designed to determine if repeated presentations of an empty sipper tube (the conditioned stimulus or CS) with the response-independent delivery of a sucrose solution (the unconditioned stimulus or US) from a second spout results in the development of Pavlovian conditioned responding. In Experiment 1, rats in the experimental condition received paired CS-US presentations whereas subjects in the control condition were exposed to random presentations of CS and US. In Experiment 2, an additional control condition (CS alone) was included and, to encourage generalized responding between the US and CS, the CS tube was filled with water for all groups. The results of both experiments indicate that the CS-directed responding in the paired CS-US condition was Pavlovian in nature. Thus, the present procedure serves as an autoshaping task in which conditioned licking is generated.

The effects of nicotine exposure during Pavlovian conditioning in rats on several measures of incentive motivation for a conditioned stimulus paired with water.

PubMed

Guy, Elizabeth Glenn; Fletcher, Paul J

2014-06-01

Nicotine enhances approach toward and operant responding for conditioned stimuli (CSs), but the effect of exposure during different phases of Pavlovian incentive learning on these measures remains to be determined. These studies examined the effects of administering nicotine early, late or throughout Pavlovian conditioning trials on discriminated approach behavior, nicotine-enhanced responding for conditioned reinforcement, extinction, and the reinstatement of responding for conditioned reinforcement. We also tested the effect of nicotine on approach to a lever-CS in a Pavlovian autoshaping procedure and for this CS to serve as a conditioned reinforcer. Thirsty rats were exposed to 13 conditioning sessions where a light/tone CS was paired with the delivery of water. Nicotine was administered either prior to the first or last seven sessions, or throughout the entire conditioning procedure. Responding for conditioned reinforcement, extinction, and the reinstatement of responding by the stimulus and nicotine were compared across exposure groups. Separately, the effects of nicotine on conditioned approach toward a lever-CS during autoshaping, and responding for that CS as a conditioned reinforcer, were examined. Nicotine exposure was necessary for nicotine-enhanced responding for conditioned reinforcement and the ability for nicotine and the stimulus to additively reinstate responding on the reinforced lever. Nicotine increased contacts with a lever-CS during autoshaping, and removal of nicotine abolished this effect. Prior nicotine exposure was necessary for nicotine-enhanced responding reinforced by the lever. Enhancements in the motivating properties of CSs by nicotine occur independently from duration and timing effects of nicotine exposure during conditioning.

Gender-dependent behavioral and sensory effects of a commercial mixture of polychlorinated biphenyls (Aroclor 1254) in rats.

PubMed

Geller, A M; Oshiro, W M; Haykal-Coates, N; Kodavanti, P R; Bushnell, P J

2001-02-01

Developmental exposure to polychlorinated biphenyls (PCBs) has been associated with behavioral and cognitive deficits in humans and animal models. Perinatal exposure to PCBs has also been associated with sensory deficits in animal models. These effects were hypothesized to be mediated in part by ortho-substituted PCBs, which do not or weakly bind to the aryl hydrocarbon (Ah) receptor. The present studies were designed to determine whether perinatal exposure to Aroclor 1254, a commercial mixture of > 99% ortho-substituted PCBs, would affect cognitive and sensory function in Long-Evans rats. Adult male and female offspring of female rats fed Aroclor 1254 (Lot #124-191; doses of 0, 1, or 6 mg/kg/day; gestational day 6 through postnatal day 21; n = eight/group) were trained to perform a signal detection task capable of assessing sensory thresholds. Training included autoshaping and operant conditioning. Thresholds for detecting a 1-s light stimulus were determined under background illuminations ranging from 2 lux to complete darkness. Female rats exposed to Aroclor 1254 autoshaped more rapidly than control females, at a rate akin to control males. Control females had lower thresholds than control males at all levels of background illumination. These differences were abolished by Aroclor 1254, which reduced thresholds in males and increased thresholds in females. These data extend previous findings of gender-specific effects of PCBs on neurobehavioral development to measures of acquisition and sensory function.

A tribute to John Gibbon.

PubMed

Church, Russell M.

2002-04-28

This article provides an overview of the published research of John Gibbon. It describes his experimental research on scalar timing and his development of scalar timing theory. It also describes his methods of research which included mathematical analysis, conditioning methods, psychophysical methods and secondary data analysis. Finally, it describes his application of scalar timing theory to avoidance and punishment, autoshaping, temporal perception and timed behavior, foraging, circadian rhythms, human timing, and the effect of drugs on timed perception and timed performance of Parkinson's patients. The research of Gibbon has shown the essential role of timing in perception, classical conditioning, instrumental learning, behavior in natural environments and in neuropsychology.

Chemogenetic manipulation of ventral pallidal neurons impairs acquisition of sign-tracking in rats.

PubMed

Chang, Stephen E; Todd, Travis P; Bucci, David J; Smith, Kyle S

2015-12-01

Cues associated with rewarding events acquire value themselves as a result of the incentive value of the reward being transferred to the cue. Consequently, presentation of a reward-paired cue can trigger reward-seeking behaviours towards the cue itself (i.e. sign-tracking). The ventral pallidum (VP) has been demonstrated to be involved in a number of motivated behaviours, both conditioned and unconditioned. However, its contribution to the acquisition of incentive value is unknown. Using a discriminative autoshaping procedure with levers, the effects of disrupting VP activity in rats on the emergence of sign-tracking was investigated using chemogenetics, i.e. Designer Receptors Exclusively Activated by Designer Drugs (DREADDs). Transient disruption of VP neurons [activation of the inhibitory hM4D(Gi) DREADD through systemic injections of clozapine N-oxide (CNO) prior to each autoshaping session] impaired acquisition of sign-tracking (lever press rate) without having any effect on approach to the site of reward delivery (i.e. goal-tracking) or on the expression of sign-tracking after it was acquired. In addition, electrophysiological recordings were conducted in freely behaving rats following VP DREADD activation. The majority of VP units that were responsive to CNO injections exhibited rapid inhibition relative to baseline, a subset of CNO-responsive units showed delayed excitation, and a smaller subset displayed a mixed response of inhibition and excitation following CNO injections. It is argued that disruption of VP during autoshaping specifically disrupted the transfer of incentive value that was attributed to the lever cue, suggesting a surprisingly fundamental role for the VP in acquiring, compared with expressing, Pavlovian incentive values. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Reward magnitude, but not time of day, influences the trial-spacing effect in autoshaping with rats.

PubMed

Thomas, B; Huneycutt, D; Papini, M R

1998-12-01

The arousal hypothesis of the trial-spacing effect suggests that spaced-trial training increases emotional arousal and thus invigorates Pavlovian behavior, relative to massed-trial conditions. Emotional arousal was manipulated by varying reinforcer magnitude during training (either one or five food pellets/trial, across groups). In addition, autoshaping training was administered either in the morning (0900 h) or in the evening (1700 h). Rats were housed in an enclosed colony room and exposed to a regular light:dark cycle (light from 0700 to 1900 h). Available evidence indicates that reinforcer magnitude and time of day are related to arousal levels. As expected, a larger reinforcer magnitude led to a highly significant trial spacing effect. Evening training led to a higher response rate than morning training, but the trial-spacing effect was equally strong whether training was administered in the morning or in the evening. These results provide partial support for the arousal hypothesis and are discussed in the context of research on schedule-induced behavior.

Differential autoshaping to common and distinctive elements of positive and negative discriminative stimuli1

PubMed Central

Wasserman, Edward A.; Anderson, Patricia A.

1974-01-01

The learning by hungry pigeons of a discrimination between two successively presented compound visual stimuli was investigated using a two-key autoshaping procedure. Common and distinctive stimulus elements were simultaneously presented on separate keys and either followed by food delivery, S+, or not, S−. The subjects acquired both between-trial and within-trial discriminations. On S+ trials, pigeons pecked the distinctive stimulus more than the common stimulus; before responding ceased on S− trials, they pecked the common stimulus more than the distinctive one. Mastery of the within-display discrimination during S+ trials preceded mastery of the between-trials discrimination. These findings extend the Jenkins-Sainsbury analysis of discriminations based upon a single distinguishing feature to discriminations in which common and distinctive elements are associated with both the positive and negative discriminative stimuli. The similarity of these findings to other effects found in autoshaping—approach to signals that forecast reinforcement and withdrawal from signals that forecast nonreinforcement—is also discussed. PMID:16811812

The effects of using stimuli from three different dimensions on autoshaping with a complex negative patterning discrimination.

PubMed

Pearce, John M; George, David N

2002-10-01

In two experiments pigeons received a complex negative patterning discrimination, using autoshaping, in which food was made available after three stimuli if they were presented alone (A, B, C), or in pairs (AB, AC, BC), but not when they were all presented together (ABC). Subjects also received a positive patterning discrimination in which three additional stimuli were not followed by food when presented alone (D, E, F), or in pairs (DE, DF, EF), but they were followed by food when presented together (DEF). Stimuli A and D belonged to one dimension, B and E to a second dimension, and D and F to a third dimension. For both problems, the discrimination between the individual stimuli and the triple-element compounds developed more readily than that between the pairs of stimuli and the triple-element compound. The results are consistent with predictions that can be derived from a configural theory of conditioning.

Dissociable effects of cingulate and medial frontal cortex lesions on stimulus-reward learning using a novel Pavlovian autoshaping procedure for the rat: implications for the neurobiology of emotion.

PubMed

Bussey, T J; Everitt, B J; Robbins, T W

1997-10-01

The effects of quinolinic acid-induced lesions of the anterior cingulate, posterior cingulate, and medial frontal cortices on stimulus-reward learning were investigated with a novel Pavlovian autoshaping procedure in an apparatus allowing the automated presentation of computer-graphic stimuli to rats (T. J. Bussey, J. L. Muir, & T. W. Robbins, 1994). White vertical rectangles were presented on the left or the right of a computer screen. One of these conditioned stimuli (the CS+) was always followed by the presentation of a sucrose pellet; the other, the CS-, was never followed by reward. With training, rats came to approach the CS+ more often than the CS-. Anterior cingulate cortex-lesioned rats failed to demonstrate normal discriminated approach, making significantly more approaches to the CS- than did sham-operated controls. Medial frontal cortex-lesioned rats acquired the task normally but had longer overall approach latencies. Posterior cingulate cortex lesions did not affect acquisition.

Chronic administration of tibolone modulates anxiety-like behavior and enhances cognitive performance in ovariectomized rats.

PubMed

Espinosa-Raya, Judith; Neri-Gómez, Teresa; Orozco-Suárez, Sandra; Campos, María G; Guerra-Araiza, Christian

2012-01-01

Hormone replacement therapy (HRT) may be prescribed to prevent the symptoms of menopause. This therapy may include estrogenic and/or progestin components and may increase the incidence of endometrial and breast cancers. Tibolone (TIB), which is also made up of estrogen and progestin components, is often used to reduce the impact of HRT. However, the effect of TIB on the processes of learning, memory and anxiety has yet to be fully elucidated. The aim of this study was to evaluate the long-term effect on learning, memory processes and anxiety in ovariectomized rats caused by different doses of TIB (0 mg/kg, 0.01 mg/kg, 0.1 mg/kg 1.0 mg/kg and 10 mg/kg, administered daily via the oral route for 18 weeks). Two behavioral animal models, the autoshaping and T maze models were employed. The concentrations of acetyl choline transferase (ChAT) and tryptophan hydroxylase (TPH) in the hippocampus were directly measured by Western blot. No significant changes were observed in the autoshaping model and spontaneous activity test. In the T maze, increased latency was observed with TIB doses of 1 and 10 mg/kg compared to the vehicle. We observed that the ChAT content decreased with increasing doses of TIB, whereas TPH content increased with doses of 1 and 10 mg/kg of TIB. These data indicate that high doses of TIB improved emotional learning, which may be related to the modulation of the cholinergic and serotonergic systems by TIB. Copyright © 2011 Elsevier Inc. All rights reserved.

Effects of amygdala lesions on overexpectation phenomena in food cup approach and autoshaping procedures.

PubMed

Holland, Peter C

2016-08-01

Prediction error (PE) plays a critical role in most modern theories of associative learning, by determining the effectiveness of conditioned stimuli (CS) or unconditioned stimuli (US). Here, we examined the effects of lesions of central (CeA) or basolateral (BLA) amygdala on performance in overexpectation tasks. In 2 experiments, after 2 CSs were separately paired with the US, they were combined and followed by the same US. In a subsequent test, we observed losses in strength of both CSs, as expected if the negative PE generated on reinforced compound trials encouraged inhibitory learning. CeA lesions, known to interfere with PE-induced enhancements in CS effectiveness, reduced those losses, suggesting that normally the negative PE also enhances cue associability in this task. BLA lesions had no effect. When a novel cue accompanied the reinforced compound, it acquired net conditioned inhibition, despite its consistent pairings with the US, consonant with US effectiveness models. That acquisition was unaffected by either CeA or BLA lesions, suggesting different rules for assignment of credit of changes in cue strength and cue associability. Finally, we examined a puzzling autoshaping phenomenon previously attributed to overexpectation effects. When a previously food-paired auditory cue was combined with the insertion of a lever and paired with the same food US, the auditory cue not only failed to block conditioning to the lever, but also lost strength, as in an overexpectation experiment. This effect was abolished by BLA lesions but unaffected by CeA lesions, suggesting it was unrelated to other overexpectation effects. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Effects of amygdala lesions on overexpectation phenomena in food cup approach and autoshaping procedures

PubMed Central

Holland, Peter C.

2016-01-01

Prediction error (PE) plays a critical role in most modern theories of associative learning, by determining the effectiveness of conditioned or unconditioned stimuli (CS or USs). Here, we examined the effects of lesions of central (CeA) or basolateral (BLA) amygdala on performance in overexpectation tasks. In two experiments, after two CSs were separately paired with the US, they were combined and followed by the same US. In a subsequent test, we observed losses in strength of both CSs, as expected if the negative PE generated on reinforced compound trials encouraged inhibitory learning. CeA lesions, known to interfere with PE-induced enhancements in CS effectiveness, reduced those losses, suggesting that normally the negative PE also enhances cue associability in this task. BLA lesions had no effect. When a novel cue accompanied the reinforced compound, it acquired net conditioned inhibition, despite its consistent pairings with the US, consonant with US effectiveness models. That acquisition was unaffected by either CeA or BLA lesions, suggesting different rules for assignment of credit of changes in cue strength and cue associability. Finally, we examined a puzzling autoshaping phenomenon previously attributed to overexpectation effects. When a previously-food-paired auditory cue was combined with the insertion of a lever and paired with the same food US, the auditory cue not only failed to block conditioning to the lever, but also lost strength, as in an overexpectation experiment. This effect was abolished by BLA lesions but unaffected by CeA lesions, suggesting it was unrelated to other overexpectation effects. PMID:27176564

Survival of the Partial Reinforcement Extinction Effect after Contextual Shifts

ERIC Educational Resources Information Center

Boughner, Robert L.; Papini, Mauricio R.

2006-01-01

The effects of contextual shifts on the partial reinforcement extinction effect (PREE) were studied in autoshaping with rats. Experiment 1 established that the two contexts used subsequently were easily discriminable and equally salient. In Experiment 2, independent groups of rats received acquisition training under partial reinforcement (PRF) or…

Effects of nimodipine on learning in normotensive and spontaneously hypertensive rats.

PubMed

Meneses, A; Terrón, J A; Ibarra, M; Hong, E

1997-04-01

It is well known that the calcium channel blocker, nimodipine, has beneficial effects on learning in either aged or hypertensive animals and humans. However, no attempts have been made to investigate if nimodipine can reverse the synergistic deleterious effects of aging and hypertension in the same subject. Therefore, this study investigated the effects of stable infusions of nimodipine in the autoshaping learning task using middle-aged normotensive (WKY) and hypertensive (SHR) rats. WKY and SHR of 12 months of age were implanted with osmotic minipumps releasing either vehicle or nimodipine (0.4 mg/kg/day). After 3 weeks of treatment, the animals received autoshaping training sessions during 4 consecutive days. The WKY animals treated with nimodipine exhibited the highest levels of learning during the last session, the rank order being WKY-nimodipine > SHR-nimodipine > WKY-vehicle > SHR-vehicle. These results confirm that nimodipine can reverse the impairing effects of either aging or hypertension on learning; the presence of both conditions, however, might produce more severe dysfunctional changes that cannot be totally reversed by nimodipine.

A comparison of pecking generated by serial, delay, and trace autoshaping procedures1

PubMed Central

Newlin, Robert J.; LoLordo, Vincent M.

1976-01-01

Pigeons were exposed to serial, delay, and trace autoshaping procedures. In Experiment I, all conditioned stimuli (CSs) were changes in illumination of the response key. The number of trials to acquisition of the keypeck increased from serial, to 4-sec delay, 8-sec delay, and 8-sec trace procedures, in that order. In Experiment II, which used a longer intertrial interval, trials to criterion increased from 8-sec delay, to 28-sec delay, 8-sec trace, and 28-sec trace procedures, in that order. In Experiment III, two groups received serial procedures in which the first CS was either a tone or a houselight, and the second was a keylight. The tone group acquired the key peck more rapidly than the houselight group. Early in conditioning in these experiments, and when the conditioned stimulus was a change in the keylight, there was a short latency to the onset of pecking and pecking was directed at the CS. After extensive conditioning, or when the CS was relatively diffuse, pecking still occurred, but had a longer latency and was not reliably directed toward the conditioned stimulus. PMID:16811907

DISRUPTION OF CONDITIONED REWARD ASSOCIATION BY TYPICAL AND ATYPICAL ANTIPSYCHOTICS

PubMed Central

Danna, C.L.; Elmer, G.I.

2013-01-01

Antipsychotic drugs are broadly classified into typical and atypical compounds; they vary in their pharmacological profile however a common component is their antagonist effects at the D2 dopamine receptors (DRD2). Unfortunately, diminished DRD2 activation is generally thought to be associated with the severity of neuroleptic-induced anhedonia. The purpose of this study was to determine the effect of the atypical antipsychotic olanzapine and typical antipsychotic haloperidol in a paradigm that reflects the learned transfer of incentive motivational properties to previously neutral stimuli, namely autoshaping. In order to provide a dosing comparison to a therapeutically relevant endpoint, both drugs were tested against amphetamine-induced disruption of prepulse inhibition as well. In the autoshaping task, rats were exposed to repeated pairings of stimuli that were differentially predictive of reward delivery. Conditioned approach to the reward predictive cue (sign-tracking) and to the reward (goal-tracking) increased during repeated pairings in the vehicle treated rats. Haloperidol and olanzapine completely abolished this behavior at relatively low doses (100 μg/kg). This same dose was the threshold dose for each drug to antagonize the sensorimotor gating deficits produced by amphetamine. At lower doses (3–30 μg/kg) both drugs produced a dose-dependent decrease in conditioned approach to the reward predictive cue. There was no difference between drugs at this dose range which indicates that olanzapine disrupts autoshaping at a significantly lower proposed DRD2 receptor occupancy. Interestingly, neither drug disrupted conditioned approach to the reward at the same dose range that disrupted conditioned approach to the reward predictive cue. Thus, haloperidol and olanzapine, at doses well below what is considered therapeutically relevant, disrupts the attribution of incentive motivational value to previously neutral cues. Drug effects on this dimension of reward processing are an important consideration in the development of future pharmacological treatments for schizophrenia. PMID:20416333

Do serotonin(1-7) receptors modulate short and long-term memory?

PubMed

Meneses, A

2007-05-01

Evidence from invertebrates to human studies indicates that serotonin (5-hydroxytryptamine; 5-HT) system modulates short- (STM) and long-term memory (LTM). This work is primarily focused on analyzing the contribution of 5-HT, cholinergic and glutamatergic receptors as well as protein synthesis to STM and LTM of an autoshaping learning task. It was observed that the inhibition of hippocampal protein synthesis or new mRNA did not produce a significant effect on autoshaping STM performance but it did impair LTM. Both non-contingent protein inhibition and 5-HT depletion showed no effects. It was basically the non-selective 5-HT receptor antagonist cyproheptadine, which facilitated STM. However, the blockade of glutamatergic and cholinergic transmission impaired STM. In contrast, the selective 5-HT(1B) receptor antagonist SB-224289 facilitated both STM and LTM. Selective receptor antagonists for the 5-HT(1A) (WAY100635), 5-HT(1D) (GR127935), 5-HT(2A) (MDL100907), 5-HT(2C/2B) (SB-200646), 5-HT(3) (ondansetron) or 5-HT(4) (GR125487), 5-HT(6) (Ro 04-6790, SB-399885 and SB-35713) or 5-HT(7) (SB-269970) did not impact STM. Nevertheless, WAY100635, MDL100907, SB-200646, GR125487, Ro 04-6790, SB-399885 or SB-357134 facilitated LTM. Notably, some of these changes shown to be independent of food-intake. Concomitantly, these data indicate that '5-HT tone via 5-HT(1B) receptors' might function in a serial manner from STM to LTM, whereas working in parallel using 5-HT(1A), 5-HT(2A), 5-HT(2B/2C), 5-HT(4), or 5-HT(6) receptors.

Evidence of Structure and Persistence in Motivational Attraction to Serial Pavlovian Cues

ERIC Educational Resources Information Center

Smedley, Elizabeth B.; Smith, Kyle S.

2018-01-01

Sign-tracking is a form of autoshaping where animals develop conditioned responding directed toward stimuli predictive of an outcome even though the outcome is not contingent on the animal's behavior. Sign-tracking behaviors are thought to arise out of the attribution of incentive salience (i.e., motivational value) to reward-predictive cues. It…

Effects of the potential 5-HT7 receptor agonist AS 19 in an autoshaping learning task.

PubMed

Perez-García, Georgina S; Meneses, A

2005-08-30

This work aimed to evaluate further the role of 5-HT7 receptors during memory formation in an autoshaping Pavlovian/instrumental learning task. Post-training administration of the potential 5-HT7 receptor agonist AS 19 or antagonist SB-269970 enhanced memory formation or had no effect, respectively. The AS 19 facilitatory effect was reversed by SB-269970, but not by the selective 5-HT1A antagonist WAY100635. Amnesia induced by scopolamine (cholinergic antagonist) or dizocilpine (NMDA antagonist) was also reversed by AS 19. Certainly, reservations regarding the selectivity of AS 19 for 5-HT7 and other 5-HT receptors in vivo are noteworthy and, therefore, its validity for use in animal models as a pharmacological tool. Having mentioned that, it should be noticed that together these data are providing further support to the notion of the 5-HT7 receptors role in memory formation. Importantly, this 5-HT7 receptor agonist AS 19 appears to represent a step forward respect to the notion that potent and selective 5-HT7 receptor agonists can be useful in the treatment of dysfunctional memory in aged-related decline and Alzheimer's disease.

Parallel learning in an autoshaping paradigm.

PubMed

Naeem, Maliha; White, Norman M

2016-08-01

In an autoshaping task, a single conditioned stimulus (CS; lever insertion) was repeatedly followed by the delivery of an unconditioned stimulus (US; food pellet into an adjacent food magazine) irrespective of the rats' behavior. After repeated training trials, some rats responded to the onset of the CS by approaching and pressing the lever (sign-trackers). Lesions of dorsolateral striatum almost completely eliminated responding to the lever CS while facilitating responding to the food magazine (US). Lesions of the dorsomedial striatum attenuated but did not eliminate responding to the lever CS. Lesions of the basolateral or central nucleus of the amygdala had no significant effects on sign-tracking, but combined lesions of the 2 structures impaired sign-tracking by significantly increasing latency to the first lever press without affecting the number of lever presses. Lesions of the dorsal hippocampus had no effect on any of the behavioral measures. The findings suggest that sign-tracking with a single lever insertion as the CS may consist of 2 separate behaviors learned in parallel: An amygdala-mediated conditioned orienting and approach response and a dorsal striatum-mediated instrumental response. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Summation and subtraction using a modified autoshaping procedure in pigeons.

PubMed

Ploog, Bertram O

2008-06-01

A modified autoshaping paradigm (significantly different from those previously reported in the summation literature) was employed to allow for the simultaneous assessment of stimulus summation and subtraction in pigeons. The response requirements and the probability of food delivery were adjusted such that towards the end of training 12 of 48 trials ended in food delivery, the same proportion as under testing. Stimuli (outlines of squares of three sizes and colors: A, B, and C) were used that could be presented separately or in any combination of two or three stimuli. Twelve of the pigeons (summation groups) were trained with either A, B, and C or with AB, BC, and CA, and tested with ABC. The remaining 12 pigeons (subtraction groups) received training with ABC but were tested with A, B, and C or with AB, BC, and CA. These groups were further subdivided according to whether stimulus elements were presented either in a concentric or dispersed manner. Summation did not occur; subtraction occurred in the two concentric groups. For interpretation of the results, configural theory, the Rescorla-Wagner model, and the composite-stimulus control model were considered. The results suggest different mechanisms responsible for summation and subtraction.

The role of autoshaping in cooperative two-player games between starlings.

PubMed

Reboreda, J C; Kacelnik, A

1993-07-01

We report a study of the behavior of starlings in laboratory situations inspired by the "prisoner's dilemma." Our purpose is to investigate some possible mechanisms for the maintenance of cooperation by reciprocity and to investigate the process of autoshaping at a trial-by-trial level. In Experiment 1, pairs of starlings housed in adjacent cages played a discrete-trial "game" in which food could be obtained only by "cooperation." In this game, pecking at a response key eliminated the opportunity to obtain food but produced food for the partner. If neither bird pecked, neither had the opportunity to obtain food in that trial. Some level of cooperation persisted for several sessions whether the birds had been pretrained for a high or low probability of pecking at the key. The probability of a cooperative response was higher after trials in which the partner responded (and a reward was obtained) than after trials in which neither bird responded (and no reward was obtained), but the probability of a response was even higher after trials in which the same bird had responded, even though no reward was obtained by the actor in these trials. This behavior did not require visual presence of another player, because similar results were obtained in Experiment 2 (a replicate of Experiment 1 in which the members of the pair could not see each other) and in Experiment 3, a game in which each starling played with a computer responding with "tit for tat." Using an omission schedule, in which food was given in all trials in which the bird did not peck, Experiment 4 showed that pecking could be maintained by autoshaping. In this experiment, overall probability of pecking decreased with experience, due to a drop in the tendency to peck in consecutive trials. The probability of pecking in trials following a reinforced trial did not decrease with experience. An implementation of the Rescorla-Wagner model for this situation was capable of reproducing molar, but not molecular, aspects of our results. The results violate the predictions of several game-theoretical models for the evolution of cooperation, including tit for tat, generous tit for tat, and the superior win-stay-lose-shift.

Pavlovian conditioning with ethanol: sign-tracking (autoshaping), conditioned incentive, and ethanol self-administration.

PubMed

Krank, Marvin D

2003-10-01

Conditioned incentive theories of addictive behavior propose that cues signaling a drug's reinforcing effects activate a central motivational state. Incentive motivation enhances drug-taking and drug-seeking behavior. We investigated the behavioral response to cues associated with ethanol and their interaction with operant self-administration of ethanol. In two experiments, rats received operant training to press a lever for a sweetened ethanol solution. After operant training, the animals were given Pavlovian pairings of a brief and localized cue light with the sweetened ethanol solution (no lever present). Lever pressing for ethanol was then re-established, and the behavioral effects of the cue light were tested during an ethanol self-administration session. The conditioned responses resulting from pairing cue lights with the opportunity to ingest ethanol had three main effects: (1) induction of operant behavior reinforced by ethanol, (2) stimulation of ethanol-seeking behavior (magazine entries), and (3) signal-directed behavior (i.e., autoshaping, or sign-tracking). Signal-directed behavior interacted with the other two effects in a manner predicted by the location of the cue light. These conditioned responses interact with operant responding for ethanol reinforcement. These findings demonstrate the importance of Pavlovian conditioning effects on ethanol self-administration and are consistent with conditioned incentive theories of addictive behavior.

Sign-tracking (autoshaping) in rats: a comparison of cocaine and food as unconditioned stimuli.

PubMed

Kearns, David N; Weiss, Stanley J

2004-11-01

A series of experiments was performed to determine whether sign-tracking would occur in rats with intravenous (i.v.) cocaine as the unconditioned stimulus. In Experiment 1, a retractable lever paired with food produced strong sign-tracking, but a lever paired with one of three doses of i.v. cocaine did not elicit any approach or contact behavior. Experiment 2 demonstrated that doses of cocaine that did not elicit sign-tracking would function as a positive reinforcer for a lever contact operant. In Experiment 3, an artificial consummatory response was added to make the cocaine reinforcement episode more behaviorally comparable to that occasioned by food. Although the rats readily performed this response when it was required to receive cocaine infusions, they still did not contact a lever that signaled the availability of these infusions. It appears that cocaine is different from other positive reinforcers (e.g., food, water, warmth, or intracranial stimulation) in that it will not produce sign-tracking in rats.

The effects of creatine pyruvate and creatine citrate on performance during high intensity exercise

PubMed Central

Jäger, Ralf; Metzger, Jan; Lautmann, Karin; Shushakov, Vladimir; Purpura, Martin; Geiss, Kurt-Reiner; Maassen, Norbert

2008-01-01

Background A double-blind, placebo-controlled, randomized study was performed to evaluate the effect of oral creatine pyruvate (Cr-Pyr) and creatine citrate (Cr-Cit) supplementation on exercise performance in healthy young athletes. Methods Performance during intermittent handgrip exercise of maximal intensity was evaluated before (pretest) and after (posttest) 28 days of Cr-Pyr (5 g/d, n = 16), Cr-Cit (5 g/d, n = 16) or placebo (pla, 5 g/d, n = 17) intake. Subjects performed ten 15-sec exercise intervals, each followed by 45 sec rest periods. Results Cr-Pyr (p < 0.001) and Cr-Cit (p < 0.01) significantly increased mean power over all intervals. Cr-Cit increased force during the first and second interval (p < 0.01) compared to placebo. The effect of Cr-Cit on force decreased over time and the improvement was not significant at the sixth and ninth interval, whereas Cr-Pyr significantly increased force during all intervals (p < 0.001). Cr-Pyr (p < 0.001) and Cr-Cit (p < 0.01) resulted in an increase in contraction velocity, whereas only Cr-Pyr intake significantly (p < 0.01) increased relaxation velocity. Oxygen consumption measured during rest periods significantly increased with Cr-Pyr (p < 0.05), whereas Cr-Cit and placebo intake did not result in significant improvements. Conclusion It is concluded that four weeks of Cr-Pyr and Cr-Cit intake significantly improves performance during intermittent handgrip exercise of maximal intensity and that Cr-Pyr might benefit endurance, due to enhanced activity of the aerobic metabolism. PMID:18269769

The touchscreen operant platform for testing learning and memory in rats and mice

PubMed Central

Horner, Alexa E.; Heath, Christopher J.; Hvoslef-Eide, Martha; Kent, Brianne A.; Kim, Chi Hun; Nilsson, Simon R. O.; Alsiö, Johan; Oomen, Charlotte A.; Holmes, Andrew; Saksida, Lisa M.; Bussey, Timothy J.

2014-01-01

Summary An increasingly popular method of assessing cognitive functions in rodents is the automated touchscreen platform, on which a number of different cognitive tests can be run in a manner very similar to touchscreen methods currently used to test human subjects. This methodology is low stress (using appetitive, rather than aversive reinforcement), has high translational potential, and lends itself to a high degree of standardisation and throughput. Applications include the study of cognition in rodent models of psychiatric and neurodegenerative diseases (e.g., Alzheimer’s disease, schizophrenia, Huntington’s disease, frontotemporal dementia), and characterisation of the role of select brain regions, neurotransmitter systems and genes in rodents. This protocol describes how to perform four touchscreen assays of learning and memory: Visual Discrimination, Object-Location Paired-Associates Learning, Visuomotor Conditional Learning and Autoshaping. It is accompanied by two further protocols using the touchscreen platform to assess executive function, working memory and pattern separation. PMID:24051959

Sex and the stimulus-movement effect: Differences in acquisition of autoshaped responding in cynomolgus monkeys.

PubMed

Rice, Nathaniel C; Makar, Jennifer R; Myers, Todd M

2017-03-15

The stimulus-movement effect refers to the phenomenon in which stimulus discrimination or acquisition of a response is facilitated by moving stimuli as opposed to stationary stimuli. The effect has been found in monkeys, rats, and humans, but the experiments conducted did not provide adequate female representation to investigate potential sex differences. The current experiment analyzed acquisition of stimulus touching in a progressive series of classical conditioning procedures in cynomolgus monkeys (Macaca fascicularis) as a function of sex and stimulus movement. Classical conditioning tasks arrange two or more stimuli in relation to each other with different temporal and predictive relations. Autoshaping procedures overlay operant contingencies onto a classical-conditioning stimulus arrangement. In the present case, a neutral stimulus (a small gray square displayed on a touchscreen) functioned as the conditional stimulus and a food pellet functioned as the unconditional stimulus. Although touching is not required to produce food, with repeated stimulus pairings subjects eventually touch the stimulus. Across conditions of increasing stimulus correlation and temporal contiguity, male monkeys acquired the response faster with a moving stimulus. In contrast, females acquired the response faster with a stationary stimulus. These results demonstrate that the stimulus-movement effect may be differentially affected by sex and indicate that additional experiments with females are needed to determine how sex interacts with behavioral phenomena discovered and elaborated almost exclusively using males. Published by Elsevier Inc.

Recovery of Pavlovian sign-tracking (autoshaping) following the discontinuation of inter-trial interval food in rats.

PubMed

Kearns, David N; Weiss, Stanley J

2007-07-01

In pigeons, Pavlovian autoshaped keypecking produced by keylight-food pairings has been eliminated by introducing food during periods between CS presentations (i.e., during the inter-trial intervals). Keypecking eliminated in this manner reappears when the inter-trial USs are discontinued even though the CS is no longer paired with US. The present experiment investigated whether this recovery of responding produced by discontinuing unpaired inter-trial US presentations could be extended to another species, rats, within a Pavlovian sign-tracking paradigm. Rats were initially trained on a procedure where insertion of one retractable lever (CS(+)) was followed, response independently, with food, while insertion of another lever (CS(-)) was not paired with food. Rats quickly came to contact the CS(+) lever at high rates, but contacted the CS(-) lever infrequently. In the next phase, CS(+) was no longer followed by food. Explicitly unpaired food was presented only during the inter-trial intervals when both levers were absent. This treatment essentially eliminated the sign-tracking response. In the final phase, the unpaired inter-trial food presentations were discontinued while both CSs continued to be presented without food. This produced a significant recovery of the sign-tracking elicited by the CS(+) lever, extending the species generality of the Pavlovian resurgence phenomenon that has previously only been reported in pigeons, to rats.

Physical restraint produces rapid acquisition of the pigeon's key peck

PubMed Central

Locurto, C. M.; Travers, Tania; Terrace, H. S.; Gibbon, John

1980-01-01

The acquisition and maintenance of autoshaped key pecking in pigeons was studied as a function of intertrial interval. At each of six intervals, which ranged from 12 seconds to 384 seconds, four pigeons were physically restrained during training while four other pigeons were not restrained. Restrained subjects acquired key pecking faster and with less intragroup variability at each interval. The effects of restraint were specific to acquisition and were not evident in maintained responding after five postacquisition sessions. PMID:16812175

Protection from extinction.

PubMed

Rescorla, Robert A

2003-05-01

The effect of the presence of a conditioned inhibitor on extinction of excitatory conditioning was studied in one magazine approach and three autoshaping experiments using rats and pigeons. In each case, the presence of an inhibitor reduced responding to an exciter during extinction but allowed substantial recovery of responding to that exciter when subsequently tested separately. Control stimuli with a history of being irrelevant to reinforcement or being nonreinforced had less of a protective effect. This constitutes a clear demonstration of protection from extinction, a phenomenon of substantial theoretical and applied importance.

Creatine Monohydrate Supplementation Does Not Augment Fitness, Performance, or Body Composition Adaptations in Response to Four Weeks of High-Intensity Interval Training in Young Females.

PubMed

Forbes, Scott C; Sletten, Nathan; Durrer, Cody; Myette-Côté, Étienne; Candow, D; Little, Jonathan P

2017-06-01

High-intensity interval training (HIIT) has been shown to improve cardiorespiratory fitness, performance, body composition, and insulin sensitivity. Creatine (Cr) supplementation may augment responses to HIIT, leading to even greater physiological adaptations. The purpose of this study was to determine the effects of 4 weeks of HIIT (three sessions/week) combined with Cr supplementation in recreationally active females. Seventeen females (age = 23 ± 4 yrs; BMI = 23.4 ± 2.4) were randomly assigned to either Cr (Cr; 0.3 g・kg -1 ・d -1 for 5 d followed by 0.1 g・kg -1 ・d -1 for 23 days; n = 9) or placebo (PLA; n = 8). Before and after the intervention, VO 2peak , ventilatory threshold (VT), time-trial performance, lean body mass and fat mass, and insulin sensitivity were assessed. HIIT improved VO 2peak (Cr = +10.2%; PLA = +8.8%), VT (Cr = +12.7%; PLA = +9.9%), and time-trial performance (Cr = -11.5%; PLA = -11.6%) with no differences between groups (time main effects, all p < .001). There were no changes over time for fat mass (Cr = -0.3%; PLA = +4.3%), whole-body lean mass (Cr = +0.5%; PLA = -0.9%), or insulin resistance (Cr = +3.9%; PLA = +18.7%). In conclusion, HIIT is an effective way to improve cardiorespiratory fitness, VT, and time-trial performance. The addition of Cr to HIIT did not augment improvements in cardiorespiratory fitness, performance or body composition in recreationally active females.

Preferred orientation in Cr- and Co-based thin films and its effects on the read/write performance of the media

NASA Astrophysics Data System (ADS)

Tsai, Hsiao-chu; Lal, Brij B.; Eltoukhy, Atef

1992-04-01

This work investigates the formation of preferred crystallographic orientation (PO) in Cr underlayer as well as CoCrTa and CoCrPtTa thin films and its effects on the recording performance of longitudinal media. The results show that the thin-film media with comparable coercivity but different crystalline PO as measured by x-ray diffraction exhibit significant difference in high-frequency signal amplitude, pulse width, and signal-to-noise ratio. To illustrate the effect of PO on parametric performance, CoCrTa/Cr and CoCrPtTa/Cr media were sputtered on different substrates and/or using special sputtering processes to achieve comparable coercivity but different PO in the films. A PO of Cr(200), which normally occurs on the NiP/Al substrates under adequate sputtering conditions, is found to be the key to obtaining a PO of Co(11.0) in Co-alloy media. The consequence of preferred in-plane c-axis orientation is a higher coercivity and better parametric performance of the medium. The formation of PO in the Cr underlayer is found to be related to the substrate material and the oxygen content in the sputtered films. The nonmetallic canasite substrates tend to promote PO of more stable Cr(110) rather than Cr(200). Consequently, this leads to a PO of out-of-plane c axis on the following Co films. The PO of magnetic layer appears to be an important factor in determining the parametric performance of the media.

Anion-exchange high-performance liquid chromatography of water-soluble chromium (VI) and chromium (III) complexes in biological materials.

PubMed

Suzuki, Y

1987-04-10

A high-performance anion-exchange liquid chromatograph coupled to visible-range (370 nm) and UV (280 nm) detectors and an atomic-absorption spectrometer allowed the rapid determination of CrVI and/or complexes of CrIII in rat plasma, erythrocyte lysate and liver supernatant treated with CrVI or CrIII in vitro. CrVI in the eluates was determined using both the visible-range detector and atomic-absorption spectrometer (AAS). The detection limits of CrVI in standard solutions using these methods were 2 and 5 ng (signal-to-noise ratio = 2), respectively. Separations of the biological components and of CrIII complexes were monitored by UV and AAS analyses, respectively. Time-related decreases of CrVI accompanied by increases in CrIII complexes were observed, indicating the reduction of CrVI by some of the biological components. The reduction rates were considerably higher in the liver supernatant and erythrocyte lysate than in the plasma. These results indicate that the anion-exchange high-performance liquid chromatographic system is useful for simultaneous determination of CrVI and CrIII complexes in biological materials.

The autoshaping procedure as a residual block clock

PubMed Central

Dinsmoor, James A.; Dougan, James D.; Pfister, John; Thiels, Edda

1992-01-01

In the first experiment, 4 pigeons were each presented with a recurring sequence of four key colors followed by the delivery of grain (block clock). Once the rate of pecking had stabilized, three of the colors were replaced, during different series of sessions, by a darkening of the key. The rate of pecking was reduced within those segments of the interval between deliveries of food during which the key was dark; when the key was dark during the final portion of the interval, rates were reduced throughout the entire interval. In the second experiment, 3 new pigeons were exposed to a different sequence of colors, and the final stimulus was replaced in successive conditions by a novel color, a darkened key, and a restoration of the original color. The data indicated that darkening the key had a more severe, more extensive, and more persistent effect than did a mere change in color. These results suggest that it may be fruitful to conceptualize the autoshaping procedure as a special version of the block clock in which pecking is suppressed throughout the greater part of the interval by darkening the key. In the final condition, the same stimulus appeared in each of the last three portions of the interval. The rate of pecking was lower during the last two portions than when distinctive colors were presented, with the peak rate now appearing in the fifth of seven equal temporal components. PMID:16812666

Effects of orbitofrontal cortex lesions on autoshaped lever pressing and reversal learning.

PubMed

Chang, Stephen E

2014-10-15

A cue associated with a rewarding event can trigger behavior towards the cue itself due to the cue acquiring incentive value through its pairing with the rewarding outcome (i.e., sign-tracking). For example, rats will approach, press, and attempt to "consume" a retractable lever conditioned stimulus (CS) that signals delivery of a food unconditioned stimulus (US). Attending to food-predictive CSs is important when seeking out food, and it is just as important to be able to modify one's behavior when the relationships between CSs and USs are changed. Using a discriminative autoshaping procedure with lever CSs, the present study investigated the effects of orbitofrontal cortex (OFC) lesions on sign-tracking and reversal learning. Insertion of one lever was followed by sucrose delivery upon retraction, and insertion of another lever was followed by nothing. After the acquisition phase, the contingencies between the levers and outcomes were reversed. Bilateral OFC lesions had no effect on the acquisition of sign-tracking. However, OFC-lesioned rats showed substantial deficits in acquiring sign-tracking compared to sham-lesioned rats once the stimulus-outcome contingencies were reversed. Over the course of reversal learning, OFC-lesioned rats were able to reach comparable levels of sign-tracking as sham-lesioned rats. These findings suggest that OFC is not necessary for the ability of a CS to acquire incentive value and provide more evidence that OFC is critical for modifying behavior appropriately following a change in stimulus-outcome contingencies. Copyright © 2014 Elsevier B.V. All rights reserved.

Role of 5-HT1-7 receptors in short- and long-term memory for an autoshaping task: intrahippocampal manipulations.

PubMed

Liy-Salmeron, Gustavo; Meneses, Alfredo

2007-05-25

It was previously reported that brain areas containing serotonin (5-hydroxytryptamine, 5-HT) receptors mediate memory consolidation as well as short (STM)- and long-term memory (LTM). Here the effects of systemic and intrahippocampal administration of 5-HT agonists and antagonists on an autoshaping learning task were explored, which requires hippocampal translation and transduction as well as 5-HT receptors expression. As previously reported ketamine (glutamatergic antagonist) and two well-known amnesic drugs, scopolamine (cholinergic antagonist) and dizocilpine (NMDA antagonist) impaired STM but not LTM; dizocilpine even improved the latter. Since ketamine produces hallucinations and impairs memory in humans, we address the question if well-known antipsychotic haloperidol and clozapine might affect STM deficit. Indeed, systemic administration of clozapine

Acute and chronic safety and efficacy of dose dependent creatine nitrate supplementation and exercise performance.

PubMed

Galvan, Elfego; Walker, Dillon K; Simbo, Sunday Y; Dalton, Ryan; Levers, Kyle; O'Connor, Abigail; Goodenough, Chelsea; Barringer, Nicholas D; Greenwood, Mike; Rasmussen, Christopher; Smith, Stephen B; Riechman, Steven E; Fluckey, James D; Murano, Peter S; Earnest, Conrad P; Kreider, Richard B

2016-01-01

Creatine monohydrate (CrM) and nitrate are popular supplements for improving exercise performance; yet have not been investigated in combination. We performed two studies to determine the safety and exercise performance-characteristics of creatine nitrate (CrN) supplementation. Study 1 participants (N = 13) ingested 1.5 g CrN (CrN-Low), 3 g CrN (CrN-High), 5 g CrM or a placebo in a randomized, crossover study (7d washout) to determine supplement safety (hepatorenal and muscle enzymes, heart rate, blood pressure and side effects) measured at time-0 (unsupplemented), 30-min, and then hourly for 5-h post-ingestion. Study 2 participants (N = 48) received the same CrN treatments vs. 3 g CrM in a randomized, double-blind, 28d trial inclusive of a 7-d interim testing period and loading sequence (4 servings/d). Day-7 and d-28 measured Tendo™ bench press performance, Wingate testing and a 6x6-s bicycle ergometer sprint. Data were analyzed using a GLM and results are reported as mean ± SD or mean change ± 95 % CI. In both studies we observed several significant, yet stochastic changes in blood markers that were not indicative of potential harm or consistent for any treatment group. Equally, all treatment groups reported a similar number of minimal side effects. In Study 2, there was a significant increase in plasma nitrates for both CrN groups by d-7, subsequently abating by d-28. Muscle creatine increased significantly by d-7 in the CrM and CrN-High groups, but then decreased by d-28 for CrN-High. By d-28, there were significant increases in bench press lifting volume (kg) for all groups (PLA, 126.6, 95 % CI 26.3, 226.8; CrM, 194.1, 95 % CI 89.0, 299.2; CrN-Low, 118.3, 95 % CI 26.1, 210.5; CrN-High, 267.2, 95 % CI 175.0, 359.4, kg). Only the CrN-High group was significantly greater than PLA (p < 0.05). Similar findings were observed for bench press peak power (PLA, 59.0, 95 % CI 4.5, 113.4; CrM, 68.6, 95 % CI 11.4, 125.8; CrN-Low, 40.9, 95 % CI -9.2, 91.0; CrN-High, 60.9, 95 % CI 10.8, 111.1, W) and average power. Creatine nitrate delivered at 3 g was well-tolerated, demonstrated similar performance benefits to 3 g CrM, in addition, within the confines of this study, there were no safety concerns.

The touchscreen operant platform for testing learning and memory in rats and mice.

PubMed

Horner, Alexa E; Heath, Christopher J; Hvoslef-Eide, Martha; Kent, Brianne A; Kim, Chi Hun; Nilsson, Simon R O; Alsiö, Johan; Oomen, Charlotte A; Holmes, Andrew; Saksida, Lisa M; Bussey, Timothy J

2013-10-01

An increasingly popular method of assessing cognitive functions in rodents is the automated touchscreen platform, on which a number of different cognitive tests can be run in a manner very similar to touchscreen methods currently used to test human subjects. This methodology is low stress (using appetitive rather than aversive reinforcement), has high translational potential and lends itself to a high degree of standardization and throughput. Applications include the study of cognition in rodent models of psychiatric and neurodegenerative diseases (e.g., Alzheimer's disease, schizophrenia, Huntington's disease, frontotemporal dementia), as well as the characterization of the role of select brain regions, neurotransmitter systems and genes in rodents. This protocol describes how to perform four touchscreen assays of learning and memory: visual discrimination, object-location paired-associates learning, visuomotor conditional learning and autoshaping. It is accompanied by two further protocols (also published in this issue) that use the touchscreen platform to assess executive function, working memory and pattern separation.

Exploring performance issues for a clinical database organized using an entity-attribute-value representation.

PubMed

Chen, R S; Nadkarni, P; Marenco, L; Levin, F; Erdos, J; Miller, P L

2000-01-01

The entity-attribute-value representation with classes and relationships (EAV/CR) provides a flexible and simple database schema to store heterogeneous biomedical data. In certain circumstances, however, the EAV/CR model is known to retrieve data less efficiently than conventionally based database schemas. To perform a pilot study that systematically quantifies performance differences for database queries directed at real-world microbiology data modeled with EAV/CR and conventional representations, and to explore the relative merits of different EAV/CR query implementation strategies. Clinical microbiology data obtained over a ten-year period were stored using both database models. Query execution times were compared for four clinically oriented attribute-centered and entity-centered queries operating under varying conditions of database size and system memory. The performance characteristics of three different EAV/CR query strategies were also examined. Performance was similar for entity-centered queries in the two database models. Performance in the EAV/CR model was approximately three to five times less efficient than its conventional counterpart for attribute-centered queries. The differences in query efficiency became slightly greater as database size increased, although they were reduced with the addition of system memory. The authors found that EAV/CR queries formulated using multiple, simple SQL statements executed in batch were more efficient than single, large SQL statements. This paper describes a pilot project to explore issues in and compare query performance for EAV/CR and conventional database representations. Although attribute-centered queries were less efficient in the EAV/CR model, these inefficiencies may be addressable, at least in part, by the use of more powerful hardware or more memory, or both.

Diagnostic quality of 50 and 100 µm computed radiography compared with screen–film mammography in operative breast specimens

PubMed Central

Pagliari, C M; Hoang, T; Reddy, M; Wilkinson, L S; Poloniecki, J D; Given-Wilson, R M

2012-01-01

Objective To compare reader ratings of the clinical diagnostic quality of 50 and 100 μm computed radiography (CR) systems with screen–film mammography (SFM) in operative specimens. Methods Mammograms of 57 fresh operative breast specimens were analysed by 10 readers. Exposures were made with identical position and compression with three mammographic systems (Fuji 100CR, 50CR and SFM). Images were anonymised and readers blinded to the CR system used. A five-point comparative scoring system (−2 to +2) was used to assess seven quality criteria and overall diagnostic value. Statistical analysis was subsequently performed of reader ratings (n=16 925). Results For most quality criteria, both CR systems were rated as equivalent to or better than SFM. The CR systems were significantly better at demonstrating skin edge and background tissue (p<1×10−5). Microcalcification was best demonstrated on the CR50 system (p<1×10−5). The overall diagnostic value of both CR systems was rated as being as good as or better than SFM (p<1×10−5). Conclusion In this clinical setting, the overall diagnostic performance of both CR systems was as good as or better than SFM, with the CR50 system performing better than the CR100. PMID:22096218

Experimental evidence of Cr magnetic moments at low temperature in Cr2A(A=Al, Ge)C.

PubMed

Jaouen, M; Bugnet, M; Jaouen, N; Ohresser, P; Mauchamp, V; Cabioc'h, T; Rogalev, A

2014-04-30

From x-ray magnetic circular dichroism experiments performed at low temperature on Cr2AlC and Cr2GeC thin films, it is evidenced that Cr atoms carry a net magnetic moment in these ternary phases. It is shown that the Cr magnetization of the Al-based compound nearly vanished at 100 K in agreement with what has been recently observed on bulk. X-ray linear dichroism measurements performed at various angles of incidence and temperatures clearly demonstrate the existence of a charge ordering along the c axis of the structure of Cr2AlC. All these experimental observations support, in part, theoretical calculations claiming that Cr dd correlations have to be considered to correctly describe the structure and properties of these Cr-based ternary phases.

Colorectal Surgery Fellowship Improves In-hospital Mortality After Colectomy and Proctectomy Irrespective of Hospital and Surgeon Volume.

PubMed

Saraidaridis, Julia T; Hashimoto, Daniel A; Chang, David C; Bordeianou, Liliana G; Kunitake, Hiroko

2018-03-01

General surgery residents are increasingly pursuing sub-specialty training in colorectal (CR) surgery. However, the majority of operations performed by CR surgeons are also performed by general surgeons. This study aimed to assess in-hospital mortality stratified by CR training status after adjusting for surgeon and hospital volume. The Statewide Planning and Research Cooperative system database was used to identify all patients who underwent colectomy/proctectomy from January 1, 2000, to December 31, 2014, in the state of New York. Operations performed by board-certified CR surgeons were identified. The relationships between CR board certification and in-hospital mortality, in-hospital complications, length of stay, and ostomy were assessed using multivariate regression models. Two hundred seventy thousand six hundred eighty-four patients underwent colectomy/proctectomy over the study period. Seventy-two thousand two hundred seventy-nine (26.7%) of operations were performed by CR surgeons. Without adjusting for hospital and surgeon volume, in-hospital mortality was lower for those undergoing colectomy/proctectomy by a CR surgeon (OR 0.49, CI 0.44-0.54, p = 0.001). After controlling for hospital and surgeon volume, the odds of inpatient mortality after colectomy/proctectomy for those operated on by CR surgeons weakened to 0.76 (CI 0.68-0.86, p = 0.001). Hospital and surgeon volume accounted for 53% of the reduction in in-hospital mortality when CR surgeons performed colectomy/proctectomy. Patients who underwent surgery by a CR surgeon had a shorter inpatient stay (0.8 days, p = 0.001) and a decreased chance of colostomy (OR 0.86, CI 0.78-0.95, p < 0.001). For patients undergoing colectomy/proctectomy, in-hospital mortality decreased when the operation was performed by a CR surgeon even after accounting for hospital and surgeon volume.

A task-invariant cognitive reserve network.

PubMed

Stern, Yaakov; Gazes, Yunglin; Razlighi, Qolomreza; Steffener, Jason; Habeck, Christian

2018-05-14

The concept of cognitive reserve (CR) can explain individual differences in susceptibility to cognitive or functional impairment in the presence of age or disease-related brain changes. Epidemiologic evidence indicates that CR helps maintain performance in the face of pathology across multiple cognitive domains. We therefore tried to identify a single, "task-invariant" CR network that is active during the performance of many disparate tasks. In imaging data acquired from 255 individuals age 20-80 while performing 12 different cognitive tasks, we used an iterative approach to derive a multivariate network that was expressed during the performance of all tasks, and whose degree of expression correlated with IQ, a proxy for CR. When applied to held out data or forward applied to fMRI data from an entirely different activation task, network expression correlated with IQ. Expression of the CR pattern accounted for additional variance in fluid reasoning performance over and above the influence of cortical thickness, and also moderated between cortical thickness and reasoning performance, consistent with the behavior of a CR network. The identification of a task-invariant CR network supports the idea that life experiences may result in brain processing differences that might provide reserve against age- or disease-related changes across multiple tasks. Copyright © 2018. Published by Elsevier Inc.

An investigation of FeCrAl cladding behavior under normal operating and loss of coolant conditions

DOE PAGES

Gamble, Kyle A.; Barani, Tommaso; Pizzocri, David; ...

2017-04-30

Iron-chromium-aluminum (FeCrAl) alloys are candidates to be used as nuclear fuel cladding for increased accident tolerance. An analysis of the response of FeCrAl under normal operating and loss of coolant conditions has been performed using fuel performance modeling. In particular, recent information on FeCrAl material properties and phenomena from separate effects tests has been implemented in the BISON fuel performance code and analyses of integral fuel rod behavior with FeCrAl cladding have been performed. BISON simulations included both light water reactor normal operation and loss-of-coolant accidental transients. In order to model fuel rod behavior during accidents, a cladding failure criterionmore » is desirable. For FeCrAl alloys, a failure criterion is developed using recent burst experiments under loss of coolant like conditions. The added material models are utilized to perform comparative studies with Zircaloy-4 under normal operating conditions and oxidizing and non-oxidizing out-of-pile loss of coolant conditions. The results indicate that for all conditions studied, FeCrAl behaves similarly to Zircaloy-4 with the exception of improved oxidation performance. Here, further experiments are required to confirm these observations.« less

An investigation of FeCrAl cladding behavior under normal operating and loss of coolant conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gamble, Kyle A.; Barani, Tommaso; Pizzocri, David

Iron-chromium-aluminum (FeCrAl) alloys are candidates to be used as nuclear fuel cladding for increased accident tolerance. An analysis of the response of FeCrAl under normal operating and loss of coolant conditions has been performed using fuel performance modeling. In particular, recent information on FeCrAl material properties and phenomena from separate effects tests has been implemented in the BISON fuel performance code and analyses of integral fuel rod behavior with FeCrAl cladding have been performed. BISON simulations included both light water reactor normal operation and loss-of-coolant accidental transients. In order to model fuel rod behavior during accidents, a cladding failure criterionmore » is desirable. For FeCrAl alloys, a failure criterion is developed using recent burst experiments under loss of coolant like conditions. The added material models are utilized to perform comparative studies with Zircaloy-4 under normal operating conditions and oxidizing and non-oxidizing out-of-pile loss of coolant conditions. The results indicate that for all conditions studied, FeCrAl behaves similarly to Zircaloy-4 with the exception of improved oxidation performance. Here, further experiments are required to confirm these observations.« less

Performance-Based Contingency Management in Cognitive Remediation Training: A Pilot Study.

PubMed

Kiluk, Brian D; Buck, Matthew B; Devore, Kathleen A; Babuscio, Theresa A; Nich, Charla; Carroll, Kathleen M

2017-01-01

Impairments in attention, working memory, and executive function are common among substance users and may adversely affect SUD treatment outcomes. The ability of cognitive remediation (CR) interventions to improve these deficits is hindered in part because levels of engagement in CR training may be inadequate to achieve benefit. This pilot study aimed to increase CR engagement and improve outcome by implementing contingency management (CM) procedures that reinforce performance improvements on CR tasks. Participants were forty individuals (50% male; 65% African American) in an outpatient substance use treatment facility with mild cognitive impairment who had ≥30-days of abstinence from alcohol and drugs. They were randomized to standard (CR-S; n=21) or CM-enhanced (CR-CM; n=19) cognitive remediation training. CR consisted of 1-hour sessions, three times per week for four weeks (12 sessions). A neuropsychological assessment battery was administered prior to and after the four-week intervention. Both groups had high rates of CR session attendance (mean CR-S=11.7, CR-CM=10.9 sessions). Performance on 8 of the 9 CR tasks significantly improved over time for both conditions, with the CR-CM condition demonstrating greater improvement on a CR Sequenced Recall task [F(1,37)=5.81, p<.05]. Significant improvement was also evident on 4 of 9 neuropsychological assessment measures, with the CR-CM condition showing differential improvement on the Trail Making Test - Part B [F (1,37)=5.34, p<.05]. These findings support the feasibility of using CM procedures to enhance substance users' engagement with CR training and suggest the potential value of more research in this area. Copyright © 2016 Elsevier Inc. All rights reserved.

Amphetamine-induced sensitization and reward uncertainty similarly enhance incentive salience for conditioned cues.

PubMed

Robinson, Mike J F; Anselme, Patrick; Suchomel, Kristen; Berridge, Kent C

2015-08-01

Amphetamine and stress can sensitize mesolimbic dopamine-related systems. In Pavlovian autoshaping, repeated exposure to uncertainty of reward prediction can enhance motivated sign-tracking or attraction to a discrete reward-predicting cue (lever-conditioned stimulus; CS+), as well as produce cross-sensitization to amphetamine. However, it remains unknown how amphetamine sensitization or repeated restraint stress interact with uncertainty in controlling CS+ incentive salience attribution reflected in sign-tracking. Here rats were tested in 3 successive phases. First, different groups underwent either induction of amphetamine sensitization or repeated restraint stress, or else were not sensitized or stressed as control groups (either saline injections only, or no stress or injection at all). All next received Pavlovian autoshaping training under either certainty conditions (100% CS-UCS association) or uncertainty conditions (50% CS-UCS association and uncertain reward magnitude). During training, rats were assessed for sign-tracking to the CS+ lever versus goal-tracking to the sucrose dish. Finally, all groups were tested for psychomotor sensitization of locomotion revealed by an amphetamine challenge. Our results confirm that reward uncertainty enhanced sign-tracking attraction toward the predictive CS+ lever, at the expense of goal-tracking. We also reported that amphetamine sensitization promoted sign-tracking even in rats trained under CS-UCS certainty conditions, raising them to sign-tracking levels equivalent to the uncertainty group. Combining amphetamine sensitization and uncertainty conditions did not add together to elevate sign-tracking further above the relatively high levels induced by either manipulation alone. In contrast, repeated restraint stress enhanced subsequent amphetamine-elicited locomotion, but did not enhance CS+ attraction. (c) 2015 APA, all rights reserved).

Nucleus accumbens neurons encode Pavlovian approach behaviors: evidence from an autoshaping paradigm.

PubMed

Day, Jeremy J; Wheeler, Robert A; Roitman, Mitchell F; Carelli, Regina M

2006-03-01

Environmental stimuli predictive of appetitive events can elicit Pavlovian approach responses that enhance an organism's ability to track and secure natural rewards, but may also contribute to the compulsive nature of drug addiction. Here, we examined the activity of individual nucleus accumbens (NAc) neurons during an autoshaping paradigm. One conditioned stimulus (CS+, a retractable lever presented for 10 s) was immediately followed by the delivery of a 45-mg sucrose pellet to a food receptacle, while another stimulus (CS-, a separate retractable lever presented for 10 s) was never followed by sucrose. Approach responses directed at the CS+ and CS- were recorded as lever presses and had no experimental consequence. Rats (n = 9) selectively approached the CS+ on more than 80% of trials and were surgically prepared for electrophysiological recording. Of 76 NAc neurons, 57 cells (75%) exhibited increases and/or decreases in firing rate (i.e. termed 'phasically active') during the CS+ presentation and corresponding approach response. Forty-seven percent of phasically active cells (27 out of 57) were characterized by time-locked but transient increases in cell firing, while 53% (30 out of 57) showed a significant reduction in firing for the duration of the CS+. In contrast, the same excitatory subpopulation exhibited smaller increases in activity relative to CS- onset, while the inhibitory subpopulation showed no change in firing during the CS- period. The magnitude and prevalence of cue-related neural responses reported here indicates that the NAc encodes biologically significant, repetitive approach responses that may model the compulsive nature of drug addiction in humans.

Amphetamine-induced sensitization and reward uncertainty similarly enhance incentive salience for conditioned cues

PubMed Central

Robinson, Mike J.F.; Anselme, Patrick; Suchomel, Kristen; Berridge, Kent C.

2015-01-01

Amphetamine and stress can sensitize mesolimbic dopamine-related systems. In Pavlovian autoshaping, repeated exposure to uncertainty of reward prediction can enhance motivated sign-tracking or attraction to a discrete reward-predicting cue (lever CS+), as well as produce cross-sensitization to amphetamine. However, it remains unknown how amphetamine-sensitization or repeated restraint stress interact with uncertainty in controlling CS+ incentive salience attribution reflected in sign-tracking. Here rats were tested in three successive phases. First, different groups underwent either induction of amphetamine sensitization or repeated restraint stress, or else were not sensitized or stressed as control groups (either saline injections only, or no stress or injection at all). All next received Pavlovian autoshaping training under either certainty conditions (100% CS-UCS association) or uncertainty conditions (50% CS-UCS association and uncertain reward magnitude). During training, rats were assessed for sign-tracking to the lever CS+ versus goal-tracking to the sucrose dish. Finally, all groups were tested for psychomotor sensitization of locomotion revealed by an amphetamine challenge. Our results confirm that reward uncertainty enhanced sign-tracking attraction toward the predictive CS+ lever, at the expense of goal-tracking. We also report that amphetamine sensitization promoted sign-tracking even in rats trained under CS-UCS certainty conditions, raising them to sign-tracking levels equivalent to the uncertainty group. Combining amphetamine sensitization and uncertainty conditions together did not add together to elevate sign-tracking further above the relatively high levels induced by either manipulation alone. In contrast, repeated restraint stress enhanced subsequent amphetamine-elicited locomotion, but did not enhance CS+ attraction. PMID:26076340

A scale-invariant internal representation of time.

PubMed

Shankar, Karthik H; Howard, Marc W

2012-01-01

We propose a principled way to construct an internal representation of the temporal stimulus history leading up to the present moment. A set of leaky integrators performs a Laplace transform on the stimulus function, and a linear operator approximates the inversion of the Laplace transform. The result is a representation of stimulus history that retains information about the temporal sequence of stimuli. This procedure naturally represents more recent stimuli more accurately than less recent stimuli; the decrement in accuracy is precisely scale invariant. This procedure also yields time cells that fire at specific latencies following the stimulus with a scale-invariant temporal spread. Combined with a simple associative memory, this representation gives rise to a moment-to-moment prediction that is also scale invariant in time. We propose that this scale-invariant representation of temporal stimulus history could serve as an underlying representation accessible to higher-level behavioral and cognitive mechanisms. In order to illustrate the potential utility of this scale-invariant representation in a variety of fields, we sketch applications using minimal performance functions to problems in classical conditioning, interval timing, scale-invariant learning in autoshaping, and the persistence of the recency effect in episodic memory across timescales.

Snpp CrIS Instrumental Status and Raw Data Record Quality Since the Mission

NASA Astrophysics Data System (ADS)

Jin, X.; Han, Y.; Sun, N.; Weng, F.; Wang, L.; Chen, Y.; Tremblay, D. A.

2014-12-01

The SNPP CrIS (cross-track infrared sounder) has been in service for more than two years. As the first operational interferometric hyper-spectral sounder onboard the new-generation polar-orbit meteorological satellite, CrIS's instrumental performance and data quality are widely concerned. NOAA/NESDIS/STAR CrIS Cal/Val team have been actively involved since the beginning of the mission. An intact record of the CrIS instrumental performance and raw data record (RDR) has been established. In this presentation, the continuous records of some critical indicators such as noise, gain, laser wavelength drifting and many other parameters related to the internal thermal status, are presented. It is found that the hardware performance is extremely stable in the past two years and the degradation is very small. These features make CrIS a great candidate for long-term climate studies. Moreover, the completeness of RDR data is another advantage of taking CrIS for climate studies. NOAA/NESDIS/STAR has recorded all of the CrIS RDR data since the launch and has been dedicated to improving the data quality.

Seedlayer and underlayer effects on the crystallographic orientation and magnetic recording performance of glass media

NASA Astrophysics Data System (ADS)

Zheng, Min; Choe, Geon; Johnson, Kenneth E.

2002-05-01

Seedlayer and underlayer effects on crystallographic orientation and recording performance were studied for CoCrPtB media sputtered on glass substrates. For this study, the seedlayers are XAl (X=Ni, Co, Ti, and Ru) and the underlayers are CrY (Y=V, Mo, W, and Ti). It was found that not only different seedlayers, but also different combinations of seedlayer and underlayer, led to different magnetic performance. NiAl and CoAl seedlayers orient the Co c axis to (10.0) and TiAl and RuAl seedlayers produce (11.0) Co orientation. For the NiAl and CoAl seedlayer, CrV and CrW underlayers develop less out-of-plane c-axis orientation and higher coercivity and coercive squareness while CrTi and CrMo underlayers work better for TiAl and RuAl seedlayers, respectively. Media with RuAl seedlayers have better parametric performance than media with NiAl and CoAl seedlayers. The detailed relationship between seedlayer and underlayer types and crystal orientation and recording performance is discussed.

Performance evaluation of three computed radiography systems using methods recommended in American Association of Physicists in Medicine Report 93

PubMed Central

Muhogora, Wilbroad; Padovani, Renato; Bonutti, Faustino; Msaki, Peter; Kazema, R.

2011-01-01

The performances of three clinical computed radiography (CR) systems, (Agfa CR 75 (with CRMD 4.0 image plates), Kodak CR 850 (with Kodak GP plates) and Kodak CR 850A (with Kodak GP plates)) were evaluated using six tests recommended in American Association of Physicists in Medicine Report 93. The results indicated variable performances with majority being within acceptable limits. The variations were mainly attributed to differences in detector formulations, plate readers’ characteristics, and aging effects. The differences of the mean low contrast scores between the imaging systems for three observers were statistically significant for Agfa and Kodak CR 850A (P=0.009) and for Kodak CR systems (P=0.006) probably because of the differences in ages. However, the differences were not statistically significant between Agfa and Kodak CR 850 (P=0.284) suggesting similar perceived image quality. The study demonstrates the need to implement quality control program regularly. PMID:21897559

Performance evaluation of three computed radiography systems using methods recommended in American Association of Physicists in Medicine Report 93.

PubMed

Muhogora, Wilbroad; Padovani, Renato; Bonutti, Faustino; Msaki, Peter; Kazema, R

2011-07-01

The performances of three clinical computed radiography (CR) systems, (Agfa CR 75 (with CRMD 4.0 image plates), Kodak CR 850 (with Kodak GP plates) and Kodak CR 850A (with Kodak GP plates)) were evaluated using six tests recommended in American Association of Physicists in Medicine Report 93. The results indicated variable performances with majority being within acceptable limits. The variations were mainly attributed to differences in detector formulations, plate readers' characteristics, and aging effects. The differences of the mean low contrast scores between the imaging systems for three observers were statistically significant for Agfa and Kodak CR 850A (P=0.009) and for Kodak CR systems (P=0.006) probably because of the differences in ages. However, the differences were not statistically significant between Agfa and Kodak CR 850 (P=0.284) suggesting similar perceived image quality. The study demonstrates the need to implement quality control program regularly.

The JPSS CrIS Instrument and the Evolution of Space-Based Infrared Sounders

NASA Technical Reports Server (NTRS)

Glumb, Ronald; Suwinski, Lawrence; Wells, Steven; Glumb, Anna; Malloy, Rebecca; Colton, Marie

2018-01-01

This paper will summarize the development of infrared sounders since the 1970s, describe the technological hurdles that were overcome to provide ever-increasing performance capabilities, and highlight the radiometric performance of the CrIS instrument on JPSS-1 (CrIS-JPSS1). This includes details of the CrIS-JPSS1 measured noise-equivalent spectral radiance (NEdN) performance, radiometric uncertainty performance utilizing a new and improved internal calibration target, short-term and long-term repeatability, spectral uncertainty, and spectral stability. In addition, the full-resolution operating modes for CrIS-JPSS1 will be reviewed, including a discussion of how these modes will be used during on-orbit characterization tests. We will provide a brief update of CrIS-SNPP on-obit performance and the production status of the CrIS instruments for JPSS-2 through JPSS-4. Current technological challenges will also be reviewed, including how ongoing research and development is enabling improvements to future sounders. The expanding usage of infrared sounding data will also be discussed, including demonstration of value via data assimilation, the roles of the public/private sector in communicating the importance of sounding data for long-term observations, and the long road to success from research to operational data products.

Synthesis and characterization of Cr-MSU-1 and its catalytic application for oxidation of styrene

NASA Astrophysics Data System (ADS)

Liu, Hong; Wang, Zhigang; Hu, Hongjiu; Liang, Yuguang; Wang, Mengyang

2009-07-01

Chromium-containing mesoporous silica material Cr-MSU-1 was synthesized using lauryl alcohol-polyoxyethylene (23) ether as templating agent under the neutral pH condition by two-step method. The sample was characterized by XRD, TEM, FT-IR, UV-Vis, ESR, ICP-AES and N 2 adsorption. Its catalytic performance for oxidation of styrene was studied. Effects of the solvent used, the styrene/H 2O 2 mole ratio and the reaction temperature and time on the oxidation of styrene over the Cr-MSU-1 catalyst were examined. The results indicate that Cr ions have been successfully incorporated into the framework of MSU-1 and the Cr-MSU-1 material has a uniform worm-like holes mesoporous structure. After Cr-MSU-1 is calcined, most of Cr 3+ is oxidized to Cr 5+ and Cr 6+ in tetrahedral coordination and no extra-framework Cr 2O 3 is formed. The Cr-MSU-1 catalyst is highly active for the selective oxidation of styrene and the main reaction products over Cr-MSU-1 are benzaldehyde and phenylacetaldehyde. Its catalytic performance remains stable within five repeated runs and no leaching is noticed for this chromium-based catalyst.

42 CFR § 512.2 - Definitions.

Code of Federal Regulations, 2010 CFR

2017-10-01

...) HEALTH CARE INFRASTRUCTURE AND MODEL PROGRAMS EPISODE PAYMENT MODEL General Provisions § 512.2... model means the model testing CR incentive payments for CR/ICR service use made in accordance with... performance year means one of the years in which the CR incentive payment model is being tested. Performance...

Reduction of Health Risks Due to Chromium(VI)Using Mesquite: A Potential Cr Phytoremediator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gardea-Torresdey, Jorge L.; Aldrich, Mary V.; Peralta-Videa, Jose R.

Chromium is a transition metal extensively used in industry. Cr mining and industrial operations account for chromium wastes at Superfund sites in the United States. A study was performed to investigate the possibility of using mesquite (Prosopis spp.), which is an indigenous desert plant species, to remove Cr from contaminated sites. In this study, mesquite plants were grown in an agar-based medium containing 75 mg L-1 and 125 mg L-1 of Cr(VI). The Cr content of leaf tissue (992 mg kg-1 of dry weight, from 125 mg L-1 of Cr(VI)) indicated that mesquite could be classified as a chromium hyperaccumulator.more » X-ray absorption spectroscopy (XAS) studies performed to experimental samples showed that mesquite roots absorbed some of the supplied Cr(VI). However, the data analyses of plant tissues demonstrated that the absorbed Cr(VI) was fully reduced to Cr(III) in the leaf tissue.« less

Transport properties of high-performance all-Heusler Co2CrSi/Cu2CrAl/Co2CrSi giant magnetoresistance device

NASA Astrophysics Data System (ADS)

Bai, Z. Q.; Lu, Y. H.; Shen, L.; Ko, V.; Han, G. C.; Feng, Y. P.

2012-05-01

Transport properties of giant magnetoresistance (MR) junction consisting of trilayer Co2CrSi/Cu2CrAl/Co2CrSi Heusler alloys (L21) are studied using first-principles approach based on density functional theory and the non-equilibrium Green's function method. Highly conductive channels are found in almost the entire k-plane when the magnetizations of the electrodes are parallel, while they are completely blocked in the antiparallel configuration, which leads to a high magnetoresistance ratio (the pessimistic MR ratio is nearly 100%). Furthermore, the calculated I-V curve shows that the device behaves as a good spin valve with a considerable disparity in currents under the parallel and antiparallel magnetic configurations of the electrodes. The Co2CrSi/Cu2CrAl/Co2CrSi junction could be useful for high-performance all-metallic current-perpendicular-to-plane giant magnetoresistance reading head for the next generation high density magnetic storage.

Cr2O3 nanoparticles: Advanced electrode materials for high performance pseudocapacitors

NASA Astrophysics Data System (ADS)

Babu, I. Manohara; William, J. Johnson; Muralidharan, G.

2017-05-01

Cr2O3 nanoparticles have been synthesized via simple and facile microwave irradiation method. The structural, morphological and electrochemical performances of Cr2O3 nanoparticles have been studied. Electrochemical analysis indicates the Cr2O3 electrodes to be good pseudocapacitor material with a specific capacitance (122 F g-1 at a constant current of 1 A g-1), high energy density (6.08 W h kg-1), large power density (218.98 W kg-1). These results allow us to state with confidence that new class of electrode materials with good electrochemical performance has been identified.

Magnetism of CrO overlayers on Fe(001)bcc surface: first principles calculations

NASA Astrophysics Data System (ADS)

Félix-Medina, Raúl Enrique; Leyva-Lucero, Manuel Andrés; Meza-Aguilar, Salvador; Demangeat, Claude

2018-04-01

Riva et al. [Surf. Sci. 621, 55 (2014)] as well as Calloni et al. [J. Phys.: Condens. Matter 26, 445001 (2014)] have studied the oxydation of Cr films deposited on Fe(001)bcc through low-energy electron diffraction, Auger electron spectroscopy and scanning tunneling microscopy. In the present work we perform a density functional approach within Quantum Expresso code in order to study structural and magnetic properties of CrO overlayers on Fe(001)bcc. The calculations are performed using DFT+U. The investigated systems include O/Cr/Fe(001)bcc, Cr/O/Fe(001)bcc, Cr0.25O0.75/Fe(001)bcc, as well as the O coverage Ox/Cr/Fe(001)bcc (x = 0.25; 0.50). We have found that the ordered CrO overlayer presents an antiferromagnetic coupling between Cr and Fe atoms. The O atoms are located closer to the Fe atoms of the surface than the Cr atoms. The ground state of the systems O/Cr/Fe(001)bcc and Cr/O/Fe(001)bcc corresponds to the O/Cr/Fe(001)bcc system with a magnetic coupling c(2 × 2). The effect of the O monolayer on Cr/Fe(001)bcc changes the ground state from p(1 × 1) ↓ to c(2 × 2) and produces an enhancement of the magnetic moments. The Ox overlayer on Cr/Fe(001)bcc produces an enhancement of the Cr magnetic moments.

Autism and Classical Eyeblink Conditioning: Performance Changes of the Conditioned Response Related to Autism Spectrum Disorder Diagnosis

PubMed Central

Welsh, John P.; Oristaglio, Jeffrey T.

2016-01-01

Changes in the timing performance of conditioned responses (CRs) acquired during trace and delay eyeblink conditioning (EBC) are presented for diagnostic subgroups of children having autism spectrum disorder (ASD) aged 6–15 years. Children diagnosed with autistic disorder (AD) were analyzed separately from children diagnosed with either Asperger’s syndrome or Pervasive developmental disorder (Asp/PDD) not otherwise specified and compared to an age- and IQ-matched group of children who were typically developing (TD). Within-subject and between-groups contrasts in CR performance on sequential exposure to trace and delay EBC were analyzed to determine whether any differences would expose underlying functional heterogeneities of the cerebral and cerebellar systems, in ASD subgroups. The EBC parameters measured were percentage CRs, CR onset latency, and CR peak latency. Neither AD nor Asp/PDD groups were impaired in CR acquisition during trace or delay EBC. Both AD and Asp/PDD altered CR timing, but not always in the same way. Although the AD group showed normal CR timing during trace EBC, the Asp/PDD group showed a significant 27 and 28 ms increase in CR onset and peak latency, respectively, during trace EBC. In contrast, the direction of the timing change was opposite during delay EBC, during which the Asp/PDD group showed a significant 29 ms decrease in CR onset latency and the AD group showed a larger 77 ms decrease in CR onset latency. Only the AD group showed a decrease in CR peak latency during delay EBC, demonstrating another difference between AD and Asp/PDD. The difference in CR onset latency during delay EBC for both AD and Asp/PDD was due to an abnormal prevalence of early onset CRs that were intermixed with CRs having normal timing, as observed both in CR onset histograms and mean CR waveforms. In conclusion, significant heterogeneity in EBC performance was apparent between diagnostic groups, and this may indicate that EBC performance can report the heterogeneity in the neurobiological predispositions for ASD. The findings will inform further explorations with larger cohorts, different sensory modalities, and different EBC paradigms and provide a reference set for future EBC studies of children having ASD and non-human models. PMID:27563293

The 3CR Chandra Snapshot Survey: Extragalactic Radio Sources with Redshifts between 1 and 1.5

NASA Astrophysics Data System (ADS)

Stuardi, C.; Missaglia, V.; Massaro, F.; Ricci, F.; Liuzzo, E.; Paggi, A.; Kraft, R. P.; Tremblay, G. R.; Baum, S. A.; O’Dea, C. P.; Wilkes, B. J.; Kuraszkiewicz, J.; Forman, W. R.; Harris, D. E.

2018-04-01

The aim of this paper is to present an analysis of newly acquired X-ray observations of 16 extragalactic radio sources listed in the Third Cambridge Revised (3CR) catalog and not previously observed by Chandra. Observations were performed during Chandra Cycle 17, extending X-ray coverage for the 3CR extragalactic catalog up to z = 1.5. Among the 16 targets, two lie at z < 0.5 (3CR 27 at z = 0.184 and 3CR 69 at z = 0.458) all of the remaining 14 have redshifts between 1.0 and 1.5. In the current sample, there are three compact steep spectrum (CSS) sources, three quasars, and an FR I radio galaxy, while the other nine are FR II radio galaxies. All radio sources have an X-ray counterpart. We measured nuclear X-ray fluxes as well as X-ray emission associated with radio jet knots, hotspots, or lobes in three energy bands: soft (0.5–1 keV), medium (1–2 keV), and hard (2–7 keV). We also performed standard X-ray spectral analysis for the four brightest nuclei. We discovered X-ray emission associated with the radio lobe of 3CR 124, a hotspot of the quasar 3CR 220.2, another hotspot of the radio galaxy 3CR 238, and the jet knot of 3CR 297. We also detected extended X-ray emission around the nuclear region of 3CR 124 and 3CR 297 on scales of several tens of kiloparsecs. Finally, we present an update on the X-ray observations performed with Chandra and XMM-Newton on the entire 3CR extragalactic catalog.

Dopamine dependency for acquisition and performance of Pavlovian conditioned response

PubMed Central

Darvas, Martin; Wunsch, Amanda M.; Gibbs, Jeffrey T.; Palmiter, Richard D.

2014-01-01

During Pavlovian conditioning, pairing of a neutral conditioned stimulus (CS) with a reward leads to conditioned reward-approach responses (CRs) that are elicited by presentation of the CS. CR behaviors can be sign tracking, in which animals engage the CS, or goal tracking, in which animals go to the reward location. We investigated CR behaviors in mice with only ∼5% of normal dopamine in the striatum using a Pavlovian conditioning paradigm. These mice had severely impaired acquisition of the CR, which was ameliorated by pharmacological restoration of dopamine synthesis with l-dopa. Surprisingly, after they had learned the CR, its expression decayed only gradually in following sessions that were conducted without l-dopa treatment. To assess specific contributions of dopamine signaling in the dorsal or ventral striatum, we performed virus-mediated restoration of dopamine synthesis in completely dopamine-deficient (DD) mice. Mice with dopamine signaling only in the dorsal striatum did not acquire a CR, whereas mice with dopamine signaling only in in the ventral striatum acquired a CR. The CR in mice with dopamine signaling only in the dorsal striatum was restored by subjecting the mice to instrumental training in which they had to interact with the CS to obtain rewards. We conclude that dopamine is essential for learning and performance of CR behavior that is predominantly goal tracking. Furthermore, although dopamine signaling in the ventral striatum is sufficient to support a CR, dopamine signaling only in the dorsal striatum can also support a CR under certain circumstances. PMID:24550305

The effect of chromic sulfate concentration and immersion time on the structures and anticorrosive performance of the Cr(III) conversion coatings on aluminum alloys

NASA Astrophysics Data System (ADS)

Chen, Wei-Kun; Bai, Ching-Yuan; Liu, Chung-Ming; Lin, Chao-Sung; Ger, Ming-Der

2010-06-01

The main purpose of this study is to develop trivalent chromium, Cr(III), conversion coatings on aluminum alloys. The influence of Cr(III) concentration and immersion time on structures and anticorrosive performance of the coatings has been investigated. Corrosion behaviors of the coatings were evaluated in a 0.5 M H 2SO 4 aqueous solution at room temperature using potentiodynamic polarization. The structure and valence state of the coatings were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The addition of Cr(III) ions to the conversion bath considerably changes structures and compositions of the coatings. The coatings with Cr oxides possess a denser and thinner structure. Moreover, the corrosion resistance of Cr(III) coatings tends to decline with increasing immersion time due to the dissolution of coatings in the dipping period. According to XPS analysis, the Cr(III) conversion coatings are composed of Cr 2O 3, Cr(OH) 3, Al 2O 3, Al(OH) 3, ZrO 2, Zr(OH) 4, AlF 3, and ZrF 4, but no hexavalent chromium component in the coatings. The result indicates that the coatings prepared in the solution with 0.01 M Cr(III) for 5 min have the smoothest and densest structure and the best anticorrosive performance among all of conversion coatings in this work.

Risk-adjusted Outcomes of Clinically Relevant Pancreatic Fistula Following Pancreatoduodenectomy: A Model for Performance Evaluation.

PubMed

McMillan, Matthew T; Soi, Sameer; Asbun, Horacio J; Ball, Chad G; Bassi, Claudio; Beane, Joal D; Behrman, Stephen W; Berger, Adam C; Bloomston, Mark; Callery, Mark P; Christein, John D; Dixon, Elijah; Drebin, Jeffrey A; Castillo, Carlos Fernandez-Del; Fisher, William E; Fong, Zhi Ven; House, Michael G; Hughes, Steven J; Kent, Tara S; Kunstman, John W; Malleo, Giuseppe; Miller, Benjamin C; Salem, Ronald R; Soares, Kevin; Valero, Vicente; Wolfgang, Christopher L; Vollmer, Charles M

2016-08-01

To evaluate surgical performance in pancreatoduodenectomy using clinically relevant postoperative pancreatic fistula (CR-POPF) occurrence as a quality indicator. Accurate assessment of surgeon and institutional performance requires (1) standardized definitions for the outcome of interest and (2) a comprehensive risk-adjustment process to control for differences in patient risk. This multinational, retrospective study of 4301 pancreatoduodenectomies involved 55 surgeons at 15 institutions. Risk for CR-POPF was assessed using the previously validated Fistula Risk Score, and pancreatic fistulas were stratified by International Study Group criteria. CR-POPF variability was evaluated and hierarchical regression analysis assessed individual surgeon and institutional performance. There was considerable variability in both CR-POPF risk and occurrence. Factors increasing the risk for CR-POPF development included increasing Fistula Risk Score (odds ratio 1.49 per point, P < 0.00001) and octreotide (odds ratio 3.30, P < 0.00001). When adjusting for risk, performance outliers were identified at the surgeon and institutional levels. Of the top 10 surgeons (≥15 cases) for nonrisk-adjusted performance, only 6 remained in this high-performing category following risk adjustment. This analysis of pancreatic fistulas following pancreatoduodenectomy demonstrates considerable variability in both the risk and occurrence of CR-POPF among surgeons and institutions. Disparities in patient risk between providers reinforce the need for comprehensive, risk-adjusted modeling when assessing performance based on procedure-specific complications. Furthermore, beyond inherent patient risk factors, surgical decision-making influences fistula outcomes.

Ambient temperature NO oxidation over Cr-based amorphous mixed oxide catalysts: effects from the second oxide components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Aiyong; Lin, Bo; Zhang, Hanlei

2017-01-01

Three series of Cr-based mixed oxides (Cr-Co, Cr-Fe, and Cr-Ni oxides) with high specific surface areas and amorphous textures were synthesized using a novel sol-gel method. These mixed oxides, in comparison to their pure metal oxide (CrOx, Co3O4, FeOx and NiO) counterparts, display enhanced performance for catalytic oxidation of low-concentration NO at room temperature. The best performing catalysts achieve 100% NO conversion for ~30 h of operation at a high space velocity of 45,000 ml g-1 h-1. The amorphous structure was found to be critical for these catalysts to maintain high activity and durability. Control of Cr/M (M=Co, Fe andmore » Ni) molar ratio, nitrate precursor decomposition temperature and catalyst calcination temperature was key to the synthesis of these highly active catalysts.« less

Time-course of 5-HT(6) receptor mRNA expression during memory consolidation and amnesia.

PubMed

Huerta-Rivas, A; Pérez-García, G; González-Espinosa, C; Meneses, A

2010-01-01

Growing evidence indicates that antagonists of the 5-hydroxytryptamine (serotonin) receptor(6) (5-HT(6)) improve memory and reverse amnesia although the mechanisms involved are poorly understood. Hence, in this paper RT-PCR was used to evaluate changes in mRNA expression of 5-HT(6) receptor in trained and untrained rats treated with the 5-HT(6) receptor antagonist SB-399885 and amnesic drugs scopolamine or dizocilpine. Changes in mRNA expression of 5-HT(6) receptor were investigated at different times in prefrontal cortex, hippocampus and striatum. Data indicated that memory in the Pavlovian/instrumental autoshaping task was a progressive process associated to reduced mRNA expression of 5-HT(6) receptor in the three structures examined. SB-399885 improved long-term memory at 48h, while the muscarinic receptor antagonist scopolamine or the non-competitive NMDA receptor antagonist dizocilpine impaired it at 24h. Autoshaping training and treatment with SB-399885 increased 5-HT(6) receptor mRNA expression in (maximum increase) prefrontal cortex and striatum, 24 or 48h. The scopolamine-induced amnesia suppressed 5-HT(6) receptor mRNA expression while the dizocilpine-induced amnesia did not modify 5-HT(6) receptor mRNA expression. SB-399885 and scopolamine or dizocilpine were able to reestablish memory and 5-HT(6) receptor mRNA expression. These data confirmed previous memory evidence and of more interest is the observation that training, SB-399885 and amnesic drugs modulated 5-HT(6) receptor mRNA expression in prefrontal cortex, hippocampus and striatum. Further investigation in different memory tasks, times and amnesia models together with more complex control groups might provide further clues. Copyright 2009 Elsevier Inc. All rights reserved.

Learning not to respond: Role of the hippocampus in withholding responses during omission training.

PubMed

White, Norman M; Naeem, Maliha

2017-02-01

Autoshaping is a Pavlovian learning paradigm in which rats experience pairings of a CS and a US independently of their behavior. When the CS is a lever inserted into the test cage and the US is food delivered to an adjacent magazine, many rats acquire a lever-pressing response called 'sign-tracking' even though that response has no effect on the occurrence of either the CS or the US. Since these lever presses are always followed by the US, it has been suggested that sign-tracking could be due to unintended reinforcement of the response. To eliminate the possibility of such instrumental learning the omission schedule, in which a response to the CS cancels the US, was introduced. Previous research has shown that training rats on autoshaping and switching them to an omission schedule generally reduces but does not eliminate sign-tracking, suggesting that it may be due to both Pavlovian and instrumental learning. In the present study naive rats trained on an omission schedule sign-tracked less than a control group exposed to random, unpaired CS and US presentations, suggesting that they learned to withhold the lever press response because of the negative contingency between that response and the US. In a second experiment rats with dorsal hippocampus lesions sign-tracked more than sham-lesioned rats on omission schedules, suggesting that this case of learning not to respond is hippocampus-based. This conclusion is consistent with many previous findings on the inability of hippocampal rats to withhold or suppress responding, and with studies suggesting that one form of extinction of learned responses in normal rats is due to competition from hippocampus-based learning not to respond. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of an acute therapeutic or rewarding dose of amphetamine on acquisition of Pavlovian autoshaping and ventral striatal dopamine signaling.

PubMed

Schuweiler, D R; Athens, J M; Thompson, J M; Vazhayil, S T; Garris, P A

2018-01-15

Rewarding doses of amphetamine increase the amplitude, duration, and frequency of dopamine transients in the ventral striatum. Debate continues at the behavioral level about which component of reward, learning or incentive salience, is signaled by these dopamine transients and thus altered in addiction. The learning hypothesis proposes that rewarding drugs result in pathological overlearning of drug-predictive cues, while the incentive sensitization hypothesis suggests that rewarding drugs result in sensitized attribution of incentive salience to drug-predictive cues. Therapeutic doses of amphetamine, such as those used to treat attention-deficit hyperactivity disorder, are hypothesized to enhance the ventral striatal dopamine transients that are critical for reward-related learning and to enhance Pavlovian learning. However, the effects of therapeutic doses of amphetamine on Pavlovian learning are poorly understood, and the effects on dopamine transients are completely unknown. We determined the effects of an acute pre-training therapeutic or rewarding amphetamine injection on the acquisition of Pavlovian autoshaping in the intact rat. We also determined the effects of these doses on electrically evoked transient-like dopamine signals using fast-scan cyclic voltammetry in the anesthetized rat. The rewarding dose enhanced the amplitude and duration of DA signals, caused acute task disengagement, impaired learning for several days, and triggered incentive sensitization. The therapeutic dose produced smaller enhancements in DA signals but did not have similar behavioral effects. These results underscore the necessity of more studies using therapeutic doses, and suggest a hybrid learning/incentive sensitization model may be required to explain the development of addiction. Copyright © 2017 Elsevier B.V. All rights reserved.

Individual Differences in the Attribution of Incentive Salience to a Pavlovian Alcohol Cue

PubMed Central

Villaruel, Franz R.; Chaudhri, Nadia

2016-01-01

Individual differences exist in the attribution of incentive salience to conditioned stimuli associated with food. Here, we investigated whether individual differences also manifested with a Pavlovian alcohol conditioned stimulus (CS). We compiled data from five experiments that used a Pavlovian autoshaping paradigm and tests of conditioned reinforcement. In all experiments, male, Long-Evans rats with unrestricted access to food and water were acclimated to 15% ethanol. Next, rats received Pavlovian autoshaping training, in which a 10 s presentation of a retractable lever served as the CS and 0.2 mL of 15% ethanol served as the unconditioned stimulus (US). Finally, rats underwent conditioned reinforcement tests in which nose-pokes to an active aperture led to brief presentations of the lever-CS, but nose-pokes to an inactive aperture had no consequence. Rats were categorized as sign-trackers, goal-trackers and intermediates based on a response bias score that reflected their tendencies to sign-track or goal-track at different times during training. We found that distinct groups of rats either consistently interacted with the lever-CS (“sign-trackers”) or routinely approached the port during the lever-CS (“goal-trackers”) across a majority of the training sessions. However, some individuals (“shifted sign-trackers”) with an early tendency to goal-track later shifted to comparable asymptotic levels of sign-tracking as the group identified as sign-trackers. The lever-CS functioned as a conditioned reinforcer for sign-trackers and shifted sign-trackers, but not for goal-trackers. These results provide evidence of robust individual differences in the extent to which a Pavlovian alcohol cue gains incentive salience and functions as a conditioned reinforcer. PMID:28082877

Individual Differences in the Attribution of Incentive Salience to a Pavlovian Alcohol Cue.

PubMed

Villaruel, Franz R; Chaudhri, Nadia

2016-01-01

Individual differences exist in the attribution of incentive salience to conditioned stimuli associated with food. Here, we investigated whether individual differences also manifested with a Pavlovian alcohol conditioned stimulus (CS). We compiled data from five experiments that used a Pavlovian autoshaping paradigm and tests of conditioned reinforcement. In all experiments, male, Long-Evans rats with unrestricted access to food and water were acclimated to 15% ethanol. Next, rats received Pavlovian autoshaping training, in which a 10 s presentation of a retractable lever served as the CS and 0.2 mL of 15% ethanol served as the unconditioned stimulus (US). Finally, rats underwent conditioned reinforcement tests in which nose-pokes to an active aperture led to brief presentations of the lever-CS, but nose-pokes to an inactive aperture had no consequence. Rats were categorized as sign-trackers, goal-trackers and intermediates based on a response bias score that reflected their tendencies to sign-track or goal-track at different times during training. We found that distinct groups of rats either consistently interacted with the lever-CS ("sign-trackers") or routinely approached the port during the lever-CS ("goal-trackers") across a majority of the training sessions. However, some individuals ("shifted sign-trackers") with an early tendency to goal-track later shifted to comparable asymptotic levels of sign-tracking as the group identified as sign-trackers. The lever-CS functioned as a conditioned reinforcer for sign-trackers and shifted sign-trackers, but not for goal-trackers. These results provide evidence of robust individual differences in the extent to which a Pavlovian alcohol cue gains incentive salience and functions as a conditioned reinforcer.

Development and impact of exercise self-efficacy types during and after cardiac rehabilitation.

PubMed

Rodgers, Wendy M; Murray, Terra C; Selzler, Anne-Marie; Norman, Paul

2013-05-01

Cardiovascular disease (CVD) is the leading cause of death in the developed world. Cardiac rehabilitation (CR) is a comprehensive treatment program centered on structured exercise that has been demonstrated to achieve significant decreases in mortality and morbidity in cardiac patients, yet few patients adhere to exercise post-CR and so fail to maintain any health benefits accrued during rehabilitation. One reason for the lack of adherence might be that CR fails to address the challenges to adherence faced by patients when they no longer have the resources and structure of CR to support them. Self-efficacy (SE) is a robust predictor of behavioral persistence. This study therefore focuses on changes in different types of SE during CR and the relationship of SE to subsequent levels of physical activity. A sample of 63 CR patients completed assessments of task, scheduling and coping SE at baseline and the end of CR, as well as self-reported exercise behavior at the end of CR and 1-month post-CR. Task SE (for performing elemental aspects of the behavior) was found to be most changed type of SE during CR and was strongly related to self-reported exercise at the end of CR. However, scheduling SE (for performing the behavior regularly) was most strongly related to self-reported exercise post-CR. These results are theoretically consistent and suggest that scheduling SE should be targeted during CR to improve post-CR exercise adherence.

Inhibition of the nitrification process in activated sludge by trivalent and hexavalent chromium, and partitioning of hexavalent chromium between sludge compartments.

PubMed

Novotnik, Breda; Zuliani, Tea; Ščančar, Janez; Milačič, Radmila

2014-06-01

The input of wastewater treatment plants (WWTPs) may contain high concentrations of Cr(III) and Cr(VI), which can affect nitrogen removal. In the present study the influence of different Cr(III) and Cr(VI) concentrations towards activated sludge nitrification was studied. To better understand the mechanisms of Cr(VI) toxicity, its reduction, adsorption and uptake in activated sludge was investigated in a batch growth system. Quantification of Cr(VI) was performed by speciated isotope dilution inductively coupled plasma mass spectrometry. It was found that Cr(VI) concentrations above 1.0 mg L(-1) and Cr(III) concentrations higher than 50 mg L(-1) negatively affected nitrification. Speciation studies indicated almost complete reduction of Cr(VI) after 24h of incubation when Cr(VI) concentrations were lower than 2.5 mg L(-1), whereas for Cr(VI) added to 5 mg L(-1) around 40% remained unreduced. The study of the partitioning of Cr in the activated sludge was performed by the addition of Cr(VI) in concentrations of 2.5 and 5.0 mg L(-1). Results revealed that Cr was allocated mainly within the intercellular compartments, whereas intracellular and adsorbed Cr represented less than 0.1% of the Cr sludge concentrations. Cr(VI) was reduced in all compartments, the most efficiently (about 94%) within the intracellular and intercellular fractions. The extent of reduction of adsorbed Cr was 92% and 80% for 2.5 and 5.0mg of Cr(VI) L(-1), respectively. The results of present investigation provide a new insight into the toxicity of Cr species towards activated sludge nitrification, which is of significant importance for the management of WWTPs in order to prevent them from inflows containing harmful Cr(VI) concentrations. Copyright © 2014 Elsevier Ltd. All rights reserved.

Chromium sorption and Cr(VI) reduction to Cr(III) by grape stalks and yohimbe bark.

PubMed

Fiol, Núria; Escudero, Carlos; Villaescusa, Isabel

2008-07-01

In this work, two low cost sorbents, grape stalks and yohimbe bark wastes were used to remove Cr(VI) and Cr(III) from aqueous solutions. Batch experiments were designed to obtain Cr(VI) and Cr(III) sorption data. The mechanism of Cr(III) and Cr(VI) removal and Cr(VI) reduction to Cr(III) by the two vegetable wastes, has been investigated. Fourier transform infrared rays (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis on solid phase were performed to determine the main functional groups that might be involved in metal uptake and to confirm the presence of Cr(III) on the sorbent, respectively. Results put into evidence that both sorbents are able to reduce Cr(VI) to its trivalent form.

Evaluation of sequential extraction procedures for soluble and insoluble hexavalent chromium compounds in workplace air samples.

PubMed

Ashley, Kevin; Applegate, Gregory T; Marcy, A Dale; Drake, Pamela L; Pierce, Paul A; Carabin, Nathalie; Demange, Martine

2009-02-01

Because toxicities may differ for Cr(VI) compounds of varying solubility, some countries and organizations have promulgated different occupational exposure limits (OELs) for soluble and insoluble hexavalent chromium (Cr(VI)) compounds, and analytical methods are needed to determine these species in workplace air samples. To address this need, international standard methods ASTM D6832 and ISO 16740 have been published that describe sequential extraction techniques for soluble and insoluble Cr(VI) in samples collected from occupational settings. However, no published performance data were previously available for these Cr(VI) sequential extraction procedures. In this work, the sequential extraction methods outlined in the relevant international standards were investigated. The procedures tested involved the use of either deionized water or an ammonium sulfate/ammonium hydroxide buffer solution to target soluble Cr(VI) species. This was followed by extraction in a sodium carbonate/sodium hydroxide buffer solution to dissolve insoluble Cr(VI) compounds. Three-step sequential extraction with (1) water, (2) sulfate buffer and (3) carbonate buffer was also investigated. Sequential extractions were carried out on spiked samples of soluble, sparingly soluble and insoluble Cr(VI) compounds, and analyses were then generally carried out by using the diphenylcarbazide method. Similar experiments were performed on paint pigment samples and on airborne particulate filter samples collected from stainless steel welding. Potential interferences from soluble and insoluble Cr(III) compounds, as well as from Fe(II), were investigated. Interferences from Cr(III) species were generally absent, while the presence of Fe(II) resulted in low Cr(VI) recoveries. Two-step sequential extraction of spiked samples with (first) either water or sulfate buffer, and then carbonate buffer, yielded quantitative recoveries of soluble Cr(VI) and insoluble Cr(VI), respectively. Three-step sequential extraction gave excessively high recoveries of soluble Cr(VI), low recoveries of sparingly soluble Cr(VI), and quantitative recoveries of insoluble Cr(VI). Experiments on paint pigment samples using two-step extraction with water and carbonate buffer yielded varying percentages of relative fractions of soluble and insoluble Cr(VI). Sequential extractions of stainless steel welding fume air filter samples demonstrated the predominance of soluble Cr(VI) compounds in such samples. The performance data obtained in this work support the Cr(VI) sequential extraction procedures described in the international standards.

Performance and mechanism of simultaneous removal of Cd(II) and Congo red from aqueous solution by hierarchical vaterite spherulites

NASA Astrophysics Data System (ADS)

Chen, Yuan-Yuan; Yu, Sheng-Hui; Jiang, Hao-Fan; Yao, Qi-Zhi; Fu, Sheng-Quan; Zhou, Gen-Tao

2018-06-01

Hierarchical vaterite spherulites, synthesized by a simple injection-precipitation method at room temperature, were applied for the simultaneous removal of heavy metal Cd(II) and dye Congo red (CR) from aqueous solution. Batch experiments reveal that the maximum removal capacities of as-prepared vaterite spherulites to Cd(II) and CR are 984.5 and 89.0 mg/g, respectively, showing excellent removal performance for Cd(II) and CR. Furthermore, in the binary Cd(II)-CR system, the removal capacity of vaterite to Cd(II) is significantly enhanced at lower CR concentration (<100 mg/L), but inhibited at higher CR concentration (>100 mg/L). In contrast, the concurrent Cd(II) shows negligible effect on the CR removal. The simultaneous removal mechanism was investigated by FESEM, EDX, XRD, FT-IR and XPS techniques. The simultaneous removal of Cd(II) and CR in the binary system is shown to be a multistep process, involving the preferential adsorption of dye CR, stabilization of CR to vaterite, coordination of the adsorbed CR molecules with Cd(II), and transformation of vaterite into otavite. Given the facile and green synthesis procedure, and effective removal of Cd(II) and CR in the binary system, the obtained vaterite spherulites have considerable practical interest in integrative treatment of wastewater contaminated by heavy metals and dyes.

Microstructure and Sliding Wear Performance of Cr7C3-(Ni,Cr)3(Al,Cr) Coating Deposited from Cr7C3 In Situ Formed Atomized Powder

NASA Astrophysics Data System (ADS)

Zhu, Hong-Bin; Shen, Jie; Gao, Feng; Yu, Yueguang; Li, Changhai

2017-01-01

This work is aimed at developing a new type of Cr7C3-(Ni,Cr)3(Al,Cr) coating for parts used in heavy-duty diesel engines. The feedstock, in which the stripe-shaped Cr7C3 was in situ formed, was firstly prepared by vacuum melting and gas atomization and then subjected by high-velocity oxy-fuel spraying to form the coatings. The carbon content, microstructure and phase constitution of the powders, as well as the sprayed coatings, were analyzed by chemical analysis, SEM and XRD. The hardness and sliding wear performance of the sprayed coatings were also tested and compared to a commercial Cr3C2-NiCr coating used on piston rings. The results showed that the content of carbon in feedstock was almost the same as designed, and that the volume content of in situ formed Cr7C3 was increased with carbon and chromium added. The major phases of the powders and sprayed coatings are Cr7C3 and Cr-alloyed Ni3Al. Only a small amount of carbon lost during the spraying process. As Cr7C3 content increased in the coatings, the microhardness at room temperature was firstly increased to about 1000Hv0.3. The microhardness of the coatings stayed almost constant, while the testing temperature was raised up to 700 °C for 0.5 h, which illustrates the potential application of the investigated coatings under high temperature conditions. The coatings containing 70 and 77 vol.% Cr7C3 showed the most promising wear resistance, lower friction coefficient and better tribological compatibility to gray cast iron counterpart than other tested Cr7C3-(Ni,Cr)3(Al,Cr) coatings and the reference Cr3C2-NiCr coating.

Experiments at SRT Using the NOAA CrIS/ATMS Proxy Data Set

NASA Technical Reports Server (NTRS)

Susskind, Joel; Kouvaris, Louis; Iredell, Lena

2011-01-01

The objectives of the talk are: (1) Assess the performance of NGAS Version-1.5.03.00 CrIS/ATMS retrieval algorithm as delivered by LaRC, modified to include the MW and IR tuning coefficients and new CrIS noise model (a) Percent acceptance (b) RMS and mean differences of T(p) vs. ECMWF truth as a function of % yield (2) Compare performance of NGAS retrieval algorithm with an AIRS Science Team Version-6 like retrieval algorithm modified at Sounder Research Team (SRT) for CrIS/ATMS

Cognitive reserve as a predictor of two year neuropsychological performance in early onset first-episode schizophrenia.

PubMed

de la Serna, Elena; Andrés-Perpiñá, Susana; Puig, Olga; Baeza, Inmaculada; Bombin, Igor; Bartrés-Faz, David; Arango, Celso; Gonzalez-Pinto, Ana; Parellada, Mara; Mayoral, María; Graell, Montserrat; Otero, Soraya; Guardia, Joan; Castro-Fornieles, Josefina

2013-01-01

The concept of cognitive reserve (CR) has been defined as individual differences in the efficient utilization of brain networks which allow some people to cope better than others with brain pathology. CR has been developed mainly in the field of aging and dementia after it was observed that there appears to be no direct relationship between the degree of brain pathology and the severity of clinical manifestations of this damage. The present study applies the concept of CR to a sample of children and adolescents with a first episode of schizophrenia, aiming to assess the possible influence of CR on neuropsychological performance after two year follow-up, controlling for the influence of clinical psychopathology. 35 patients meeting DSM-IV criteria for schizophrenia or schizoaffective disorder (SSD) and 98 healthy controls (HC) matched for age and gender were included. CR was assessed at baseline, taking into account premorbid IQ, educational-occupational level and leisure activities. Clinical and neuropsychological assessments were completed by all patients at two year follow-up. The CR proxy was able to predict working memory and attention at two year follow-up. Verbal memory and cognitive flexibility were not predicted by any of the variables included in the regression model. The SSD group obtained lower scores than HC on CR. CR measures correctly classified 79.8% of the sample as being SSD or HC. Lower scores on CR were observed in SSD than in HC and the CR measure correctly classified a high percentage of the sample into the two groups. CR may predict SSD performance on working memory and attention tasks. Copyright © 2012 Elsevier B.V. All rights reserved.

Effects of supplemental nanoparticle trivalent chromium on the nutrient utilization, growth performance and serum traits of broilers.

PubMed

Lin, Y C; Huang, J T; Li, M Z; Cheng, C Y; Lien, T F

2015-02-01

The aim of this study was to investigate the effect of dietary supplementation of nanoparticle trivalent chromium on nutrient utilization, growth performance and serum traits of broilers. This study included two trials. In trial 1, 32 three-week-old broilers were divided into four groups: the control, chromium chloride (CrCl3), chromium picolinate (CrPic) and nanoparticle chromium picolinate (NanoCrPic). Chromium was added at a 1200 μg/kg level to evaluate the nutrient and chromium utilization. In trial 2, 160 one-day-old broilers were randomly divided into four groups as in trial 1, with four replicates. The results of trial 1 indicated that the chromium utilization is as follows: NanoCrPic > CrPic > CrCl3 and control groups, with significant differences between groups (p < 0.05). Crude fat utilization in CrCl3 group was lower than in that the control group (p < 0.05). The results of trial 2 indicated that feed intake of 4-5 weeks showed better result in the CrCl3 group than that in the CrPic group (p < 0.05). The results of serum traits indicated that the LDL-cholesterol in the NanoCrPic groups was lower than that in the CrPic group (p < 0.05). The NanoCrpic and CrPic groups showed significantly increased serum chromium concentration when compared with the control and CrCl3 groups; the triglyceride level in the CrCl3 group was lower than that in the CrPic group (p < 0.05). This study concluded that compared with CrPic, NanoCrpic supplementation could increase chromium utilization and lower the serum LDL-cholesterol of broilers. Journal of Animal Physiology and Animal Nutrition © 2014 Blackwell Verlag GmbH.

Oxidation studies of Fe10CrAl-RE alloys exposed to Pb at 550 °C for 10,000 h

NASA Astrophysics Data System (ADS)

Ejenstam, Jesper; Halvarsson, Mats; Weidow, Jonathan; Jönsson, Bo; Szakalos, Peter

2013-11-01

Five experimental FeCrAl-RE alloys have been exposed up to 10,000 h in stagnant liquid Pb at 550 °C. The test matrix consisted of three 10 wt.% Cr alloys, with an Al content ranging from 4 to 8 wt.% (10Cr-4Al, 10Cr-6Al and 10Cr-8Al), one alloy without additions of reactive elements (RE) (10Cr-6Al), and one reference alloy with 21 wt.% Cr and 5 wt.% Al (21Cr-5Al). The evaluation showed a clear difference in oxidation properties, and it was possible to divide the alloys into two distinct groups. A critical Al concentration in the interval of 4-6 wt.% at the given RE content was required to form a thin protective oxide. However, the absence of RE addition in one of the two 10Cr-6Al alloys resulted in a significant reduction in oxidation resistance, comparable with 10Cr-4Al. None of the alloys were severely corroded, however Pb penetrated to a relatively large extent into the porous oxide of the low performing alloys. A 100 nm thick oxide scale, partly consisting of alumina (Al2O3), was observed for the high performing 10Cr-6Al alloy. The Fe10CrAl-RE alloys showed overall very good corrosion resistance and are hence a promising new alloy category for liquid Pb applications.

Response surface methodology investigation into optimization of the removal condition and mechanism of Cr(Ⅵ) by Na2SO3/CaO.

PubMed

Zhao, Shengxin; Chen, Zhonglin; Shen, Jimin; Kang, Jing; Qu, Yanfeng; Wang, Binyuan; Wang, Xin; Yuan, Lie

2017-11-01

The removal of Cr(Ⅵ) by chemical reduction-precipitation is widely applied in wastewater treatment plants. Nevertheless, the formation of Cr(OH) 3 with gel properties has weak settlement performance, making it necessary to add a coagulant aid to reduce the settling time and improve the settling effect. In this investigation, a high concentration of Cr(Ⅵ) was removed using Na 2 SO 3 as a reducing agent and CaO as a coagulant. An improved reduction and precipitation experiment was modeled by applying a three-factor central composite experimental design (CCD). To reveal as many mechanisms as possible for Cr T removal, other verification experiments were performed. The Cr T removal efficiency decreased, which can be explained by the following three reasons: dissolution of Cr(Ⅲ), competition for adsorption between Ca 2+ and Cr(Ⅲ) at different coagulation times, and formation of a solubility complex with Cr(Ⅲ) due to the surplus SO 3 2- in solution. The increasing Cr T removal efficiency can be explained by the following two reasons: dissolved Ca 2+ from CaO can neutralize CrO 2 - that is produced by the dissolution of Cr(OH) 3 in alkaline solution and can broaden the optimal final pH range of coagulation. Ca 2+ could also strengthen the Cr T removal through adsorption bridging and co-precipitation with CaO as the core of flocs. Copyright © 2017 Elsevier Ltd. All rights reserved.

The operant-respondent distinction: Future directions

PubMed Central

Pear, Joseph J.; Eldridge, Gloria D.

1984-01-01

The operant-respondent distinction has provided a major organizing framework for the data generated through the experimental analysis of behavior. Problems have been encountered, however, in using it as an explanatory concept for such phenomena as avoidance and conditioned suppression. Data now exist that do not fit neatly into the framework. Moreover, the discovery of autoshaping has highlighted difficulties in isolating the two types of behavior and conditioning. Despite these problems, the operant-respondent framework remains the most successful paradigm currently available for organizing behavioral data. Research and theoretical efforts should therefore probably be directed to modifying the framework to account for disparate data. PMID:16812402

Pavlovian contingencies and temporal information.

PubMed

Balsam, Peter D; Fairhurst, Stephen; Gallistel, Charles R

2006-07-01

The effects of altering the contingency between the conditioned stimulus (CS) and the unconditioned stimulus (US) on the acquisition of autoshaped responding was investigated by changing the frequency of unsignaled USs during the intertrial interval. The addition of the unsignaled USs had an effect on acquisition speed comparable with that of massing trials. The effects of these manipulations can be understood in terms of their effect on the amount of information (number of bits) that the average CS conveys to the subject about the timing of the next US. The number of reinforced CSs prior to acquisition is inversely related to the information content of the CS.

Speciation of chromium using reversed phase-high performance liquid chromatography coupled to different spectrometric detection methods

NASA Astrophysics Data System (ADS)

Andrle, C. M.; Jakubowski, N.; Broekaert, J. A. C.

1997-02-01

Speciation of Cr(III) and Cr(VI) based on the formation of different complexes with ammonium-pyrrolidinedithioate (APDC) in a continuous flow technique and their preconcentration using solid phase extraction (SPE) have been elaborated and applied to the analysis of waste waters from the galvanic industry. The Cr complexes were separated and determined using reversed phase-high performance liquid chromatography (RP-HPLC) coupled to different detection methods, namely UV-detection, graphite furnace-atomic absorption spectrometry (GF-AAS) and inductively coupled plasma mass spectrometry with hydraulic high pressure nebulization (HHPN/ICP-MS). After optimization the detection limits for Cr(III) and Cr(VI) of all methods are at the μg 1 -1 level and the precision in terms of RSD is 5% ( cCr = 100 μg 1 -1, N = 10). The procedure was applied to the determination of Cr(III) and Cr(VI) at the μg 1 -1 level in galvanic waste waters, and its accuracy was approved by comparing the results with those of independent methods.

Synthesis and Luminescence Characteristics of Cr 3+ doped Y 3Al 5O 12 Phosphors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Brenda A.; Dabestani, Reza T.; Lewis, Linda A.

2015-10-01

Luminescence performance of yttrium aluminum garnet (Y 3Al 5O 12) phosphors as a function of Cr 3+ concentration has been investigated via two different wet-chemical synthesis techniques, direct- (DP) and hydrothermal-precipitation (HP). Using either of these methods, the red-emitting phosphor [Y 3Al 5-xCr xO 12 (YAG: Cr 3+)] showed similar photoluminescence (PL) intensities once the dopant concentration was optimized. Specifically, the YAG: Cr 3+ PL emission intensity reached a maximum at Cr3+ concentrations of x = 0.02 (0.4 at.%) and x = 0.13 (2.6 at.%) for DP and HP processed samples, respectively. The results indicated the strong influence of themore » processing method on the optimized YAG: Cr 3+ performance, where a more effective energy transfer rate between a pair of Cr3+ activators at low concentration levels was observed by using the DP synthesis technique. Development of a highly efficient phosphor, using a facile synthesis approach, could significantly benefit consumer and industrial applications by improving the operational efficiency of a wide range of practical devices.« less

Preparation and Oxidation Performance of Y and Ce-Modified Cr Coating on open-cell Ni-Cr-Fe Alloy Foam by the Pack Cementation

NASA Astrophysics Data System (ADS)

Pang, Q.; Hu, Z. L.; Wu, G. H.

2016-12-01

Metallic foams with a high fraction of porosity, low density and high-energy absorption capacity are a rapidly emerging class of novel ultralight weight materials for various engineering applications. In this study, Y-Cr and Ce-Cr-coated Ni-Cr-Fe alloy foams were prepared via the pack cementation method, and the effects of Y and Ce addition on the coating microstructure and oxidation performance were analyzed in order to improve the oxidation resistance of open-cell nickel-based alloy foams. The results show that the Ce-Cr coating is relatively more uniform and has a denser distribution on the surface of the nickel-based alloy foam. The surface grains of the Ce-Cr-coated alloy foam are finer compared to those of the Y-Cr-coated alloy foam. An obvious Ce peak appears on the interface between the coating and the alloy foam strut, which gives rise to a "site-blocking" effect for the short-circuit transport of the cation in the substrate. X-ray diffraction analysis shows that the Y-Cr-coated alloy foam mainly consists of Cr, (Fe, Ni) and (Ni, Cr) phases in the surface layer. The Ce-Cr-coated alloy foam is mainly composed of Cr and (Ni, Cr) phases. Furthermore, the addition of Y and Ce clearly lead to an improvement in the oxidation resistance of the coated alloy foams in the temperature range of 900-1000 °C. The addition of Ce is especially effective in enhancing the diffusion of chromium to the oxidation front, thus, accelerating the formation of a Cr2O3 layer.

Effects of Supplemental Chromium Source and Concentration on Growth Performance, Carcass Traits, and Meat Quality of Broilers Under Heat Stress Conditions.

PubMed

Huang, Yanling; Yang, Jian; Xiao, Fang; Lloyd, Karen; Lin, Xi

2016-03-01

The objective of this study was to investigate the effects of dietary supplemental chromium (Cr) on growth performance, carcass traits, and meat quality of broilers reared under heat stress. A total of 252 1-d-old Cobb 500 commercial female broilers were randomly allotted by body weight (BW) to one of six replicate cages (six broilers per cage) for each of seven treatments in a completely randomized design involving a 2 × 3 factorial arrangement of treatments with three Cr sources (Cr propionate, CrPro; Cr picolinate, CrPic; Cr chloride, CrCl3) and two concentrations of added Cr (0.4, or 2.0 mg of Cr/kg) plus a Cr-unsupplemented control group. Feed and distilled-deionized water were available ad libitum for an experimental phase of 42 days. For induction of heat stress, the house temperature was set at 33 ± 2 °C from 15 to 42 days of age. Results showed that birds supplemented with Cr, regardless of Cr source, had increased ADG (P = 0.032) than controls. Birds fed 2.0 mg Cr/kg diet had greater ADG (P = 0.005) than birds fed 0.4 mg Cr/kg diet. Compared to controls, birds fed with Cr had greater dressing percentage (P = 0.021). Percentage of abdominal fat decreased (P = 0.013), whereas, breast intramuscular fat (IMF) remained unaffected (P = 0.147) in Cr supplemented vs control broilers. Broilers supplemented Cr had decreased b* values of meat color (P = 0.042) in breast muscle. B*values were also lesser (P = 0.049) in birds fed CrPro than birds supplemented with CrCl3 or CrPic. Regardless of Cr source, the percentage of cooking loss was decreased (P = 0.025) with Cr supplementation in breast muscle when compared to controls. Results from this study indicate that Cr supplementation, independent of its source, could promote growth and improve carcass traits and meat quality of broilers under heat stress conditions. Chromium propionate seems to have greater beneficial effects on meat color in comparison with CrPic and CrCl3.

Cognitive Performances Are Selectively Enhanced during Chronic Caloric Restriction or Resveratrol Supplementation in a Primate

PubMed Central

Marchal, Julia; Picq, Jean-Luc; Aujard, Fabienne

2011-01-01

Effects of an 18-month treatment with a moderate, chronic caloric restriction (CR) or an oral supplementation with resveratrol (RSV), a potential CR mimetic, on cognitive and motor performances were studied in non-human primates, grey mouse lemurs (Microcebus murinus). Thirty-three adult male mouse lemurs were assigned to three different groups: a control (CTL) group fed ad libitum, a CR group fed 70% of the CTL caloric intake, and an RSV group (RSV supplementation of 200 mg.kg−1.day−1) fed ad libitum. Three different cognitive tests, two motor tests, one emotional test and an analysis of cortisol level were performed in each group. Compared to CTL animals, CR or RSV animals did not show any change in motor performances evaluated by rotarod and jump tests, but an increase in spontaneous locomotor activity was observed in both groups. Working memory was improved by both treatments in the spontaneous alternation task. Despite a trend for CR group, only RSV supplementation increased spatial memory performances in the circular platform task. Finally, none of these treatments induced additional stress to the animals as reflected by similar results in the open field test and cortisol analyses compared to CTL animals. The present data provided the earliest evidence for a beneficial effect of CR or RSV supplementation on specific cognitive functions in a primate. Taken together, these results suggest that RSV could be a good candidate to mimic long-term CR effects and support the growing evidences that nutritional interventions can have beneficial effects on brain functions even in adults. PMID:21304942

Brain metabolic correlates of decision making in amnestic mild cognitive impairment.

PubMed

Griffith, H Randall; Okonkwo, Ozioma C; den Hollander, Jan A; Belue, Katherine; Copeland, Jacqueline; Harrell, Lindy E; Brockington, John C; Clark, David G; Marson, Daniel C

2010-01-01

Persons with amnestic mild cognitive impairment (MCI) have subtle impairments in medical decision-making capacity (MDC). We examined the relationship between proton magnetic resonance spectroscopy (MRS) and MDC in MCI. Twenty-nine MCI patients and 42 controls underwent MRS to obtain ratios of N-acetylaspartate (NAA)/Creatine (Cr), Choline (Cho)/Cr, and myo-Inositol (mI)/Cr of the posterior cingulate. They also completed the Capacity to Consent to Treatment Instrument (CCTI), a vignette-based instrument measuring decisional standards of expressing choice, appreciating consequences of choice, providing rational reasons for choice, and understanding treatment choices. Patients showed abnormal MRS ratios of mI/Cr and Cho/Cr compared to controls, and impairments on the CCTI understanding and reasoning Standards. Performance on the reasoning standard of the CCTI was correlated with NAA/Cr (r = .46, p < .05). The relationship of NAA/Cr with decision-making suggests a role for posterior cortical neuronal functioning in performance of complex IADLs in MCI.

Disruption of Putrescine Biosynthesis in Shewanella oneidensis Enhances Biofilm Cohesiveness and Performance in Cr(VI) Immobilization

PubMed Central

Ding, Yuanzhao; Peng, Ni; Du, Yonghua; Ji, Lianghui

2014-01-01

Although biofilm-based bioprocesses have been increasingly used in various applications, the long-term robust and efficient biofilm performance remains one of the main bottlenecks. In this study, we demonstrated that biofilm cohesiveness and performance of Shewanella oneidensis can be enhanced through disrupting putrescine biosynthesis. Through random transposon mutagenesis library screening, one hyperadherent mutant strain, CP2-1-S1, exhibiting an enhanced capability in biofilm formation, was obtained. Comparative analysis of the performance of biofilms formed by S. oneidensis MR-1 wild type (WT) and CP2-1-S1 in removing dichromate (Cr2O72−), i.e., Cr(VI), from the aqueous phase showed that, compared with the WT biofilms, CP2-1-S1 biofilms displayed a substantially lower rate of cell detachment upon exposure to Cr(VI), suggesting a higher cohesiveness of the mutant biofilms. In addition, the amount of Cr(III) immobilized by CP2-1-S1 biofilms was much larger, indicating an enhanced performance in Cr(VI) bioremediation. We further showed that speF, a putrescine biosynthesis gene, was disrupted in CP2-1-S1 and that the biofilm phenotypes could be restored by both genetic and chemical complementations. Our results also demonstrated an important role of putrescine in mediating matrix disassembly in S. oneidensis biofilms. PMID:24362428

Chromium basalts - Experimental determination of redox states and partitioning among synthetic silicate phases

NASA Technical Reports Server (NTRS)

Schreiber, H. D.; Haskin, L. A.

1976-01-01

Experiments were performed on silicate compositions in the forsterite-anorthite-silica and forsterite-anorthite-diopside systems to determine the relative amounts of Cr(II), Cr(III), and Cr(VI) over a wide range of oxygen partial pressures from 10 to the -10th to 1 atm at 1500 and 1550 C. Redox states were measured by visible absorption spectroscopy and electron paramagnetic resonance spectroscopy and titration. It was found that Cr is present almost exclusively as Cr(III) in terrestrial basaltic liquids and as a mixture of Cr(III) and Cr(II) in lunar basaltic liquids.

Caloric restriction in young rats disturbs hippocampal neurogenesis and spatial learning.

PubMed

Cardoso, Armando; Marrana, Francisco; Andrade, José P

2016-09-01

It is widely known that caloric restriction (CR) has benefits on several organic systems, including the central nervous system. However, the majority of the CR studies was performed in adult animals and the information about the consequences on young populations is limited. In this study, we analyzed the effects of young-onset CR, started at 4weeks of age, in the number of neuropeptide Y (NPY)-containing neurons and in neurogenesis of the hippocampal formation, using doublecortin (DCX) and Ki67 as markers. Knowing that CR treatment could interfere with exploratory activity, anxiety, learning and memory we have analyzed the performance of the rats in the open-field, elevated plus-maze and Morris water maze tests. Animals aged 4weeks were randomly assigned to control or CR groups. Controls were maintained in the ad libitum regimen during 2months. The adolescent CR rats were fed, during 2months, with 60% of the amount of food consumed by controls. We have found that young-onset CR treatment did not affect the total number of NPY-immunopositive neurons in dentate hilus, CA3 and CA1 hippocampal subfields and did not change the exploratory activity and anxiety levels. Interestingly, we have found that young-onset CR might affect spatial learning process since those animals showed worse performance during the acquisition phase of Morris water maze. Furthermore, young-onset CR induced alterations of neurogenesis in the dentate subgranular layer that seems to underlie the impairment of spatial learning. Our data suggest that adolescent animals are vulnerable to CR treatment and that this diet is not suitable to be applied in this age phase. Copyright © 2016 Elsevier Inc. All rights reserved.

The Relationships Between Cognitive Reserve and Creativity. A Study on American Aging Population.

PubMed

Colombo, Barbara; Antonietti, Alessandro; Daneau, Brendan

2018-01-01

The Cognitive Reserve (CR) hypothesis suggests that the brain actively attempts to cope with neural damages by using pre-existing cognitive processing approaches or by enlisting compensatory approaches. This would allow an individual with high CR to better cope with aging than an individual with lower CR. Many of the proxies used to assess CR indirectly refer to the flexibility of thought. The present paper aims at directly exploring the relationships between CR and creativity, a skill that includes flexible thinking. We tested a sample of 72 adults (aged between 45 and 78) assessing both their level of CR and their creativity. To evaluate CR we used the proxies commonly used in literature, namely, three subtests from the WAIS (vocabulary, similarities, and digit span) and the years of education. We also used an ad-hoc test asking people to report how frequently they tend to perform activities that are believed to increase CR. We used verbal creativity tasks (alternative uses and generation of acronyms) to assess individual levels of creativity. We asked participants to describe their main occupation (present or past) and coded each occupation as creative or not creative. Results (controlling for age-related differences) showed that scores from the WAIS correlated positively with creativity performance, even though correlations varied across the subtests. Focusing on the frequency and type of activities that people perform, and comparing individuals who have or had a creative job to those with a routine job, a clear relationship between creativity and CR emerged. This effect was more relevant than the level of job complexity. Implications for the study of CR and aging are discussed.

The Relationships Between Cognitive Reserve and Creativity. A Study on American Aging Population

PubMed Central

Colombo, Barbara; Antonietti, Alessandro; Daneau, Brendan

2018-01-01

The Cognitive Reserve (CR) hypothesis suggests that the brain actively attempts to cope with neural damages by using pre-existing cognitive processing approaches or by enlisting compensatory approaches. This would allow an individual with high CR to better cope with aging than an individual with lower CR. Many of the proxies used to assess CR indirectly refer to the flexibility of thought. The present paper aims at directly exploring the relationships between CR and creativity, a skill that includes flexible thinking. We tested a sample of 72 adults (aged between 45 and 78) assessing both their level of CR and their creativity. To evaluate CR we used the proxies commonly used in literature, namely, three subtests from the WAIS (vocabulary, similarities, and digit span) and the years of education. We also used an ad-hoc test asking people to report how frequently they tend to perform activities that are believed to increase CR. We used verbal creativity tasks (alternative uses and generation of acronyms) to assess individual levels of creativity. We asked participants to describe their main occupation (present or past) and coded each occupation as creative or not creative. Results (controlling for age-related differences) showed that scores from the WAIS correlated positively with creativity performance, even though correlations varied across the subtests. Focusing on the frequency and type of activities that people perform, and comparing individuals who have or had a creative job to those with a routine job, a clear relationship between creativity and CR emerged. This effect was more relevant than the level of job complexity. Implications for the study of CR and aging are discussed. PMID:29875716

Porous CrN thin films by selectively etching CrCuN for symmetric supercapacitors

NASA Astrophysics Data System (ADS)

Wei, Binbin; Mei, Gui; Liang, Hanfeng; Qi, Zhengbing; Zhang, Dongfang; Shen, Hao; Wang, Zhoucheng

2018-05-01

Transition metal nitrides are regarded as a new class of excellent electrode materials for high-performance supercapacitors due to their superior chemical stability and excellent electrical conductivity. We synthesize successfully the porous CrN thin films for binder-free supercapacitor electrodes by reactive magnetron co-sputtering and selective chemical etching. The porous CrN thin film electrodes exhibit high-capacitance performance (31.3 mF cm-2 at 1.0 mA cm-2) and reasonable cycling stability (94% retention after 20000 cycles). Moreover, the specific capacitance is more than two-fold higher than that of the CrN thin film electrodes in previous work. In addition, a symmetric supercapacitor device with a maximum energy density of 14.4 mWh cm-3 and a maximum power density of 6.6 W cm-3 is achieved. These findings demonstrate that the porous CrN thin films will have potential applications in supercapacitors.

High Temperature Behavior of Cr3C2-NiCr Coatings in the Actual Coal-Fired Boiler Environment

NASA Astrophysics Data System (ADS)

Bhatia, Rakesh; Sidhu, Hazoor Singh; Sidhu, Buta Singh

2015-03-01

Erosion-corrosion is a serious problem observed in steam-powered electricity generation plants, and industrial waste incinerators. In the present study, four compositions of Cr3C2-(Ni-20Cr) alloy coating powder were deposited by high-velocity oxy-fuel spray technique on T-91 boiler tube steel. The cyclic studies were performed in a coal-fired boiler at 1123 K ± 10 K (850 °C ± 10 °C). X-ray diffraction, scanning electron microscopy/energy dispersive X-ray analysis and elemental mapping analysis techniques were used to analyze the corrosion products. All the coatings deposited on T-91 boiler tube steel imparted hot corrosion resistance. The 65 pctCr3C2 -35 pct (Ni-20Cr)-coated T-91 steel sample performed better than all other coated samples in the given environment.

The Analysis of the General Performance and Mechanical Behavior of Unirradiated FeCrAl Alloys Before and After Welding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gussev, Maxim N.; Field, Kevin G.; Yamamoto, Yukinori

2016-06-03

The present report summarizes and discusses the preliminary results for the in-depth characterization of the modern, nuclear-grade FeCrAl alloys currently under development. The alloys were designed for enhanced radiation tolerance and weldability, and the research is currently being pursued by the Department of Energy (DOE) Nuclear Energy Enabling Technologies (NEET) program. Last year, seven candidate FeCrAl alloys with well-controlled chemistry and microstructures were designed and produced; welding was performed under well-controlled conditions. The structure and general performance of unirradiated alloys were assessed using standardized and advanced microstructural characterization techniques and mechanical testing. The primary objective is to identify the bestmore » candidate alloy, or at a minimum to identify the contributing factors that increase the weldability and radiation tolerance of FeCrAl alloys, therefore enabling future generations of FeCrAl alloys to deliver better performance parameters. This report is structured so as to describe these critical assessments of the weldability; radiation tolerance will be reported on in later reports from this program.« less

Creatine, arginine alpha-ketoglutarate, amino acids, and medium-chain triglycerides and endurance and performance.

PubMed

Little, Jonathan P; Forbes, Scott C; Candow, Darren G; Cornish, Stephen M; Chilibeck, Philip D

2008-10-01

Creatine (Cr) supplementation increases muscle mass, strength, and power. Arginine a-ketoglutarate (A-AKG) is a precursor for nitric oxide production and has the potential to improve blood flow and nutrient delivery (i.e., Cr) to muscles. This study compared a commercial dietary supplement of Cr, A-AKG, glutamine, taurine, branched-chain amino acids, and medium-chain triglycerides with Cr alone or placebo on exercise performance and body composition. Thirty-five men (approximately 23 yr) were randomized to Cr + A-AKG (0.1 g . kg(-1) . d(-1) Cr + 0.075 g . kg(-1) . d(-1)A-AKG, n = 12), Cr (0.1 g . kg(-1) . d(-1), n = 11), or placebo (1 g . kg(-1) . d(-1) sucrose, n = 12) for 10 d. Body composition, muscle endurance (bench press), and peak and average power (Wingate tests) were measured before and after supplementation. Bench-press repetitions over 3 sets increased with Cr + A-AKG (30.9 +/- 6.6 +/- 34.9 +/- 8.7 reps; p < .01) and Cr (27.6 +/- 5.9 +/- 31.0 +/- 7.6 reps; p < .01), with no change for placebo (26.8 +/- 5.0 +/- 27.1 +/- 6.3 reps). Peak power significantly increased in Cr + A-AKG (741 +/- 112 +/- 794 +/- 92 W; p < .01), with no changes in Cr (722 +/- 138 +/- 730 +/- 144 W) and placebo (696 +/- 63 +/- 705 +/- 77 W). There were no differences in average power between groups over time. Only the Cr-only group increased total body mass (79.9 +/- 13.0 +/- 81.1 +/- 13.8 kg; p < .01), with no significant changes in lean-tissue or fat mass. These results suggest that Cr alone and in combination with A-AKG improves upper body muscle endurance, and Cr + A-AKG supplementation improves peak power output on repeated Wingate tests.

Mild caloric restriction up-regulates the expression of prohibitin: A proteome study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takahashi, Shoko; Masuda, Junko; Shimagami, Hiroshi

2011-02-18

Research highlights: {yields} Proteomic analysis was performed to elucidate physiological alterations induced by mild CR. {yields} The results suggest good reproducibility and possibility to grasp the important response of CR. {yields} The increase in prohibitin abundance was observed in CR groups by proteomic analysis. {yields} We hypothesize that prohibitin might be involved in the longevity induced by CR. -- Abstract: Caloric restriction (CR) is well known to expand lifespan in a variety of species and to retard many age-related diseases. The effects of relatively mild CR on the proteome profile in relation to lifespan have not yet been reported, despitemore » the more extensive studies of the stricter CR conditions. Thus, the present study was conducted to elucidate the protein profiles in rat livers after mild CR for a relatively short time. Young growing rats were fed CR diets (10% and 30% CR) for 1 month. We performed the differential proteomic analysis of the rat livers using two-dimensional electrophoresis combined with MALDI-TOF mass spectrometry. The most remarkable protein among the differentially expressed proteins was found to be prohibitin, the abundance of which was increased by 30% CR. Prohibitin is a ubiquitously expressed protein shown to suppress cell proliferation and to be related to longevity. The increase in prohibitin was observed both in 10% and 30% CR by Western blot analysis. Furthermore, induction of AMP-activated kinase (AMPK) protein, related to the actions of prohibitin in promoting longevity, was observed. The increased prohibitin level in response to subtle CR suggests that this increase may be one of the early events leading to the expansion of lifespan in response to CR.« less

Impact of neutron irradiation on mechanical performance of FeCrAl alloy laser-beam weldments

NASA Astrophysics Data System (ADS)

Gussev, M. N.; Cakmak, E.; Field, K. G.

2018-06-01

Oxidation-resistant iron-chromium-aluminum (FeCrAl) alloys demonstrate better performance in Loss-of-Coolant Accidents, compared with austenitic- and zirconium-based alloys. However, further deployment of FeCrAl-based materials requires detailed characterization of their performance under irradiation; moreover, since welding is one of the key operations in fabrication of light water reactor fuel cladding, FeCrAl alloy weldment performance and properties also should be determined prior to and after irradiation. Here, advanced C35M alloy (Fe-13%Cr-5%Al) and variants with aluminum (+2%) or titanium carbide (+1%) additions were characterized after neutron irradiation in Oak Ridge National Laboratory's High Flux Isotope Reactor at 1.8-1.9 dpa in a temperature range of 195-559 °C. Specimen sets included as-received (AR) materials and specimens after controlled laser-beam welding. Tensile tests with digital image correlation (DIC), scanning electron microscopy-electron back scatter diffraction analysis, fractography, and x-ray tomography analysis were performed. DIC allowed for investigating local yield stress in the weldments, deformation hardening behavior, and plastic anisotropy. Both AR and welded material revealed a high degree of radiation-induced hardening for low-temperature irradiation; however, irradiation at high-temperatures (i.e., 559 °C) had little overall effect on the mechanical performance.

Cr(VI) Adsorption on Red Mud Modified by Lanthanum: Performance, Kinetics and Mechanisms

PubMed Central

Cui, You-Wei; Li, Jie; Du, Zhao-Fu; Peng, Yong-Zhen

2016-01-01

Water pollution caused by the highly toxic metal hexavalent chromium (Cr(VI)) creates significant human health and ecological risks. In this study, a novel adsorbent was used to treat Cr(VI)-containing wastewater; the adsorbent was prepared using red mud (RM) generated from the alumina production industry and the rare earth element lanthanum. This study explored adsorption performance, kinetics, and mechanisms. Results showed that the adsorption kinetics of the RM modified by lanthanum (La-RM), followed the pseudo-second-order model, with a rapid adsorption rate. Cr(VI) adsorption was positively associated with the absorbent dose, pH, temperature, and initial Cr(VI) concentration; coexisting anions had little impact. The maximum Cr(VI) adsorption capacity was 17.35 mg/g. Cr(VI) adsorption on La-RM was a mono-layer adsorption pattern, following the Langmuir isotherm model. Thermodynamic parameters showed the adsorption was spontaneous and endothermic. The adsorption of Cr(VI) on La-RM occurred as a result of LaOCl formation on the RM surface, which in turn further reacted with Cr(VI) in the wastewater. This study highlighted a method for converting industrial waste into a valuable material for wastewater treatment. The novel absorbent could be used as a potential adsorbent for treating Cr(VI)-contaminating wastewater, due to its cost-effectiveness and high adsorption capability. PMID:27658113

The effect of Be and Cr electrode deposition rate on the performance of MIS solar cells

NASA Astrophysics Data System (ADS)

Moharram, A. H.; Panayotatos, P.; Yeh, J. L.; Lalevic, B.

1985-07-01

An experimental study has been performed on MIS solar cells with Be, Cr and layered Cr-Be electrodes on single crystal Si, Wacker and Monsanto poly-Si substrates. Electrical characterization in the dark and under illumination was correlated to X-ray and Auger spectroscopy results. It was found that the electrode deposition rate directly affects the oxygen content of the electrodes for all metal-substrate configurations. This oxygen is believed to originate from the deposition ambient as well as from the SiO2 layer. In the case of cells with Cr and layered Cr-Be electrodes oxygen acts to reduce the electrode work function (thus increasing the open-circuit voltage) in direct proportion to the relative content of oxygen to chromium.

The use of stable isotopes for Cr(VI) determination in silty-clay soil solution.

PubMed

Zuliani, Tea; Sčančar, Janez; Milačič, Radmila

2013-09-01

In assessing the environmental hazard of Cr(VI) present in soil, exchangeable Cr(VI) is important, since it can be easily washed out from the upper part of the soil into subsurface soil, surface and ground water, and taken up by plants. The aim of this study was to evaluate the degree of species interconversion that may occur during the extraction of exchangeable Cr(VI) from silty-clay soil with phosphate buffer in order to establish an extraction method that would be effective, accurate and with minimal or no species interconversions. The Cr(VI) concentration in soil extracts was determined by speciated isotope dilution inductively coupled plasma mass spectrometry (SID-ICP-MS). The study was performed on soil samples from a field treated with tannery waste for 17 years. Samples were spiked by enriched stable isotopic solutions of (50)Cr(VI) and (53)Cr(III) that were added to phosphate buffers (0.1 M KH2PO4-K2HPO4 (pH 7.2) and/or 0.1 M K2HPO4 (pH 8)). To optimize extraction, mechanical shaking and/or ultrasound-assisted extraction were compared. The separation and detection of Cr species was performed by high-performance liquid chromatography (HPLC) ICP-MS. When mechanical shaking was applied, 90 % reduction of Cr(VI) was induced by extraction with 0.1 M KH2PO4-K2HPO4, while with 0.1 M K2HPO4 reduction was around 40 %. To shorten the extraction time and the possibility of species interconversions, ultrasound-assisted extraction was further applied only with 0.1 M K2HPO4. For total extraction of exchangeable Cr(VI) with a maximum 10 % reduction of Cr(VI), five consecutive ultrasound-assisted extractions were needed.

Electrical resistivity of V-Cr-Ti alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zinkle, S.J.; Gubbi, A.N.; Eatherly, W.S.

1997-04-01

Room temperature electrical resistivity measurements have been performed on vanadium alloys containing 3-6%Cr and 3-6%Ti in order to evaluate the microstructural stability of these alloys. A nonlinear dependence on Cr and Ti concentration was observed, which suggests that either short range ordering or solute precipitation (perhaps in concert with interstitial solute clustering) has occurred in V-6Cr-6Ti.

Dietary Supplementation with Pioglitazone Hydrochloride and Chromium Methionine Improves Growth Performance, Meat Quality, and Antioxidant Ability in Finishing Pigs.

PubMed

Jin, Cheng-Long; Wang, Qiang; Zhang, Zong-Ming; Xu, Yin-Long; Yan, Hui-Chao; Li, Hai-Chang; Gao, Chun-Qi; Wang, Xiu-Qi

2018-05-02

This work was designed to investigate the synergistic effects of pioglitazone hydrochloride (PGZ) and chromium methionine (CrMet) on meat quality, muscle fatty acid profile, and antioxidant ability of pigs. Pigs in four groups were fed a basic diet or basic diet supplemented with 15 mg/kg of PGZ, 200 μg/kg of CrMet, or 15 mg/kg of PGZ + 200 μg/kg of CrMet. In comparison to the control group, the average daily feed intake, feed/gain ratio, and serum high-density lipoprotein level decreased in the PGZ + CrMet group. Dietary PGZ + CrMet supplementation increased carcass dressing percentage, intramuscular fat, and marbling score. The percentages of C18:1ω-9c, C18:2ω-6c, C18:3ω-3, and polyunsaturated fatty acid (PUFA) in the longissimus thoracis muscle were increased in the PGZ + CrMet group. Greater superoxide dismutase and glutathione peroxidase activities were observed in the PGZ + CrMet group compared to the control group. Collectively, these findings suggested that feed with PGZ and CrMet improved the growth performance and meat quality, especially for PUFA proportions and antioxidant ability.

Sorption of Cr(III) ion from aqueous solution by two kinds of modified diatomite.

PubMed

Li, Er; Zeng, Xiangying

2012-01-01

Raw diatomite modified by microemulsion (DMM) and manganese oxide (MnD) were used for the removal of Cr(III) ions from aqueous solution. The characteristics and performance of these two types of modified diatomite on Cr(III) ion adsorption were compared. The results indicate that the Cr(III) ion adsorption capacities of diatomite were considerably improved after modifications by manganese oxide (MnO) and microemulsion. The surface area of MnD was increased because of the formation of MnO on the diatomite surface, and that of DMM was promoted owing to the existence of the hydrolyzed aromatic acid. Because of the stronger surface ionized function, the adsorption performance of Cr(III) ions in DMM was better than that in MnD. Within the experimental range of pH (i.e. 2.2-6.3), the Cr(III) ion removal of DMM (35-70%) was higher than that of MnD (33-59%) owing to the different electrostatic forces between the Cr(III) ion and the surface of the modified diatomite. The Cr(III) ion removal in MnD and DMM was improved with the increase of synthetic solution concentration in volumes from 0 to 2,500 mL.

Plasticity of lifelong calorie-restricted C57BL/6J mice in adapting to a medium-fat diet intervention at old age.

PubMed

Rusli, Fenni; Boekschoten, Mark V; Borelli, Vincenzo; Sun, Chen; Lute, Carolien; Menke, Aswin L; van den Heuvel, Joost; Salvioli, Stefano; Franceschi, Claudio; Müller, Michael; Steegenga, Wilma T

2018-04-01

Calorie restriction (CR) is a dietary regimen that supports healthy aging. In this study, we investigated the systemic and liver-specific responses caused by a diet switch to a medium-fat (MF) diet in 24-month-old lifelong, CR-exposed mice. This study aimed to increase the knowledge base on dietary alterations of gerontological relevance. Nine-week-old C57BL/6J mice were exposed either to a control, CR, or MF diet. At the age of 24 months, a subset of mice of the CR group was transferred to ad libitumMF feeding (CR-MF). The mice were sacrificed at the age of 28 months, and then, biochemical and molecular analyses were performed. Our results showed that, despite the long-term exposure to the CR regimen, mice in the CR-MF group displayed hyperphagia, rapid weight gain, and hepatic steatosis. However, no hepatic fibrosis/injury or alteration in CR-improved survival was observed in the diet switch group. The liver transcriptomic profile of CR-MF mice largely shifted to a profile similar to the MF-fed animals but leaving ~22% of the 1,578 differentially regulated genes between the CR and MF diet groups comparable with the expression of the lifelong CR group. Therefore, although the diet switch was performed at an old age, the CR-MF-exposed mice showed plasticity in coping with the challenge of a MF diet without developing severe liver pathologies. © 2017 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

Measurement of physical performance by field tests in programs of cardiac rehabilitation: a systematic review and meta-analysis.

PubMed

Travensolo, Cristiane; Goessler, Karla; Poton, Roberto; Pinto, Roberta Ramos; Polito, Marcos Doederlein

2018-04-13

The literature concerning the effects of cardiac rehabilitation (CR) on field tests results is inconsistent. To perform a systematic review with meta-analysis on field tests results after programs of CR. Studies published in PubMed and Web of Science databases until May 2016 were analyzed. The standard difference in means correct by bias (Hedges' g) was used as effect size (g) to measure que amount of modifications in performance of field tests after CR period. Potential differences between subgroups were analyzed by Q-test based on ANOVA. Fifteen studies published between 1996 e 2016 were included in the review, 932 patients and age ranged 54,4 - 75,3 years old. Fourteen studies used the six-minutes walking test to evaluate the exercise capacity and one study used the Shuttle Walk Test. The random Hedges's g was 0.617 (P<0.001), representing a drop of 20% in the performance of field test after CR. The meta-regression showed significantly association (P=0.01) to aerobic exercise duration, i.e., for each 1-min increase in aerobic exercise duration, there is a 0.02 increase in effect size for performance in the field test. Field tests can detect physical modification after CR, and the large duration of aerobic exercise during CR was associated with a better result. Copyright © 2018 Sociedade Portuguesa de Cardiologia. Publicado por Elsevier España, S.L.U. All rights reserved.

Physical evaluation of a needle photostimulable phosphor based CR mammography system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marshall, Nicholas W.; Lemmens, Kim; Bosmans, Hilde

2012-02-15

Purpose: Needle phosphor based computed radiography (CR) systems promise improved image quality compared to powder phosphor based CR units for x-ray screening mammography. This paper compares the imaging performance of needle CR cassettes, powder based CR cassettes and a well established amorphous selenium (a-Se) based flat panel based mammography system, using consistent beam qualities. Methods: Detector performance was assessed using modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE). Mammography system performance was assessed against levels from the European Guidelines, including threshold gold thickness (c-d), relative signal difference to noise (SdNR) and mean glandular dose,more » for automatic exposure control settings suggested by the manufacturers. The needle based Agfa HM5.0 CR detector was compared against the single sided readout Agfa MM3.0R and dual sided readout Fuji Profect CS powder CR plates using a 28 kV Mo/Rh spectrum, while a 28 kV W/Rh spectrum was used to compare the Agfa HM5.0 against the Siemens MAMMOMAT Inspiration a-Se based system. Results: MTF at 5 mm{sup -1} was 0.16 and 0.24 for the needle CR detector in the fast and slow scan directions, respectively, indicating a slight improvement ({approx}20%) over the two powder CR systems but remained 50% lower than the result at 5 mm{sup -1} for the a-Se detector ({approx}0.55). Structured screen noise was lower for the needle phosphor compared to the powder plates. CR system gain, estimated from the measured absorption fraction and NNPS results, was 6.3 for the (single sided) needle phosphor and 5.1 and 7.2 for the single sided and dual sided powder phosphor systems. Peak DQE at {approx}100 {mu}Gy was 0.47 for the needle system compared to peak DQE figures of 0.33 and 0.46 for the single sided readout powder plates and dual sided readout plates. The high frequency DQE (at 5 mm{sup -1}) was 0.19 for the needle CR plates, a factor of approximately 3 greater than for the powder CR plates. At 28 kV W/Rh, 2 mm Al, peak DQE for the needle CR system was 0.45 against a value of 0.50 for the a-Se detector. The needle CR detector reached the Acceptable limit for 0.1 mm details in the European Guidelines at a mean glandular dose (MGD) of approximately 1.31 mGy imaged at 28 kV Mo/Rh, compared to figures of 2.19 and 1.43 mGy for the single sided and dual sided readout powder CR systems. The a-Se detector could reach the limit at 0.65 mGy using a 28 kV W/Rh spectrum, while the needle CR system required 1.09 mGy for the same spectrum. Conclusions: Imaging performance for the needle CR phosphor technology, characterized using MTF and DQE and threshold gold thickness demonstrated a clear improvement compared to both single and dual sided reading powder phosphor based CR systems.« less

Synthesis and electrochemical characterization of Li 1.05RE xCr yMn 2- x- yO 4 spinel as cathode material for rechargeable Li-battery

NASA Astrophysics Data System (ADS)

Xie, Yanting; Yang, Rudong; Yan, Lan; Qi, Lu; Dai, Kehua; He, Ping

The spinel phases of Li 1.05RE xCr yMn 2- x- yO 4 (RE = Sc, Ce, Pr, Tb; 0 ≤ x ≤ 0.05; 0 ≤ y ≤ 0.1) were prepared by a soft chemical method. The structural and electrochemical properties of Li 1.05RE xCr yMn 2- x- yO 4 were investigated by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and charge-discharge experiments. Rare earth element-Sc and transition metal-Cr as co-substituents stabilize the spinel framework and improve charge-discharge performance. For Li 1.05Sc 0.01Cr 0.03Mn 1.96O 4, the capacity of the cell maintained 95% of the initial capacity at the 80th cycle. The rare earth elements of the variable valent metals such as Ce 3+/4+, Pr 3+/4+, Tb 3+/4+ with transition metal Cr 3+ as co-substituent do not stable framework of spinel or improve the cycling performance. Cyclic voltammetry (CV) were measured to provide clues for the improved cycling performance of cathode electrodes.

Launcher Roadmap for the CrVI Substitution of Surface Treatments. Screening of Trivalent-Chromium Conversion Solutions and First Promising Results for Repair Applications on Aluminium Alloys

NASA Astrophysics Data System (ADS)

Debout, Vincent; Pettier, Sophie

2014-06-01

Airbus Defence and Space, Space System is involved in a global roadmap for launchers in order to substitute hexavalent chromium (CrVI) and Cadmium in the current surface treatments on metallic structures.Within this framework, a screening of trivalent chromium (CrIII) conversion solutions for touch-up applications has been carried out since this step is crucial to perform local application or to repair minor damages on launcher structures but it leads to higher risks of exposure for the workers.Three commercial CrIII conversion solutions have been evaluated on high performance aluminum alloys such as AA2024 T3 and AA7175 T7351 that are often used as structural materials.This preliminary investigation highlights the effect of surface preparation, rinsing and conversion process on the final corrosion performance of conversion coatings (CCs). The results are also discussed in terms of visual aspect and adhesion with new Cr-free primers.Two operating sets of parameters are identified with promising results that represent the first steps towards the development of a new Cr-free touch-up process.

The NPOESS Crosstrack Infrared Sounder (CrIS) and Advanced Technology Microwave Sounder (ATMS) as a Companion to the New Generation AIRS/AMSU and IASI/AMSU Sounder Suites

NASA Astrophysics Data System (ADS)

Bingham, G. E.; Pougatchev, N. S.; Zavyalov, V.; Esplin, M.; Blackwell, W. J.; Barnet, C.

2009-12-01

The NPOESS Preparatory Project is serving the operations and research community as the bridge mission between the Earth Observing System and the National Polar-orbiting Operational Environmental Satellite System. The Cross-track Infrared Sounder (CrIS), combined with the Advanced Technology Microwave Sounder (ATMS) are the core instruments to provide the key performance temperature and humidity profiles (along with some other atmospheric constituent information). Both the high spectral resolution CrIS and the upgraded microwave sounder (ATMS) will be working in parallel with already orbiting Advanced Atmospheric Infrared Sounder (AIRS/AMSU) on EOS AQUA platform and Infrared Atmospheric Sounding Interferometer (IASI/AMSU) on METOP-A satellite. This presentation will review the CrIS/ATMS capabilities in the context of continuity with the excellent performance records established by AIRS and IASI. The CrIS sensor is in the process of its final calibration and characterization testing and the results and Sensor Data Record process are being validated against this excellent dataset. The comparison between CrIS, AIRS, and IASI will include spectral, spatial, radiometric performance and sounding capability comparisons.

Changes in selected serum parameters of broiler chicken fed supplemental chromium.

PubMed

Króliczewska, B; Zawadzki, W; Dobrzanski, Z; Kaczmarek-Oliwa, A

2004-12-01

The present study was conducted to evaluate the effect of chromium (Cr) from Cr yeast on the growth performance and total cholesterol, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, triglycerides, glucose, total protein and Cr concentration in the serum of broiler chicken. The birds were fed a control diet or a control diet supplemented with Cr at a level of 300, 500 microg/kg Cr. The supplementation of 500 mug/kg Cr increased body weight, weight gain and feed efficiency (p < 0.05). In addition, supplementation with Cr decreased the serum total cholesterol, LDL cholesterol (p < 0.05), triglycerides (p < 0.05) and glucose (p < 0.05) concentrations whereas serum HDL cholesterol increased. Serum total protein and serum Cr concentration slightly but not significantly increased in both Cr groups. The study suggest that Cr supplementation particularly at 500 microg/kg Cr from Cr yeast can influence on carbohydrate and lipid metabolism of broiler chicken and can be used as additives in animal diet but it still needs more investigations.

Effect of chromium picolinate supplementation on growth performance and meat characteristics of swine.

PubMed

Zhang, Hongbing; Dong, Baojun; Zhang, Minhong; Yang, Jiajun

2011-06-01

The purpose of this study was to evaluate the effect of supplemental chromium (Cr) in the form of chromium picolinate (CrPic) on swine growth performance, meat quality, and protein deposition in skeletal muscle. Forty-eight piglets were divided into three groups randomly, fed with three different dietary levels of Cr (common basal feedstuff supplemented with a dose of 1.61 μg/g or 3.22 μg/g CrPic, which corresponded to 0.2 and 0.4 μg/g Cr). Results indicated that during the growing period (1-35 days), pigs fed with the diet supplemented with CrPic showed no improvement in body mass, average daily gain (ADG), feed consumption, or feed conversion rate (FCR) (P > 0.05). During the finishing period, a supplementary dose of 0.2 μg Cr/g improved daily weight gain significantly (P < 0.05), while the situation had no significance with 0.4 μg Cr/g (P > 0.05) supplemented. For the entire growing-finishing period, body mass increased by 3.86%, ADG rose by 6.08%, and the FCR decreased by 3.30%; levels of total muscular pigment and that in the ribeye areas significantly improved (P < 0.05) when supplementation with 0.2 μg Cr/g (P < 0.05) was employed. However, there were no significant changes when supplemented with 0.4 μg Cr/g. While there were no changes in yield of carcass, back fat, water holding capacity, or levels of muscular crude protein and fat (P > 0.05) in treatment, the ratio of fat-lean and RNA/DNA increased significantly supplemented with 0.2 μg Cr/g (P < 0.05), but there were no significance with 0.4 μg Cr/g supplementation. In addition, the muscular levels of cholesterol had slightly decreased and the content of DNA in skeletal muscle showed no marked changes with 0.2 or 0.4 μg/g Cr supplementation. In conclusion, the present results suggested that dietary Cr supplementation in the dose of 0.2 μg/g could promote the growth performance, carcass characteristics, and protein deposition.

Magnetic cluster expansion simulation and experimental study of high temperature magnetic properties of Fe-Cr alloys.

PubMed

Lavrentiev, M Yu; Mergia, K; Gjoka, M; Nguyen-Manh, D; Apostolopoulos, G; Dudarev, S L

2012-08-15

We present a combined experimental and computational study of high temperature magnetic properties of Fe-Cr alloys with chromium content up to about 20 at.%. The magnetic cluster expansion method is applied to model the magnetic properties of random Fe-Cr alloys, and in particular the Curie transition temperature, as a function of alloy composition. We find that at low (3-6 at.%) Cr content the Curie temperature increases with the increase of Cr concentration. It is maximum at approximately 6 at.% Cr and then decreases for higher Cr content. The same feature is found in thermo-magnetic measurements performed on model Fe-Cr alloys, where a 5 at.% Cr alloy has a higher Curie temperature than pure Fe. The Curie temperatures of 10 and 15 at.% Cr alloys are found to be lower than the Curie temperature of pure Fe.

Investigation of Coronal Leakage of Root Fillings after Smear Layer Removal with EDTA or Er,Cr:YSGG Laser through Capillary Flow Porometry

PubMed Central

Vergauwen, Tom Edgard Maria; Michiels, Rafaël; Torbeyns, Dries; Meire, Maarten; De Moor, Roeland Jozef Gentil

2014-01-01

No studies have been performed evaluating the marginal seal of root fillings after direct exposure of root canal (RC) walls to Er,Cr:YSGG laser irradiation. Therefore, 75 root filled teeth (5 × 15–cold lateral condensation) were analyzed for through-and-through leakage (TTL) using capillary flow porometry (CFP). The cleaning protocol determined the experimental groups: (1) irrigation with NaOCl 2.5% and EDTA 17% or standard protocol (SP), (2) SP + Er,Cr:YSGG lasing (dried RC), (3) NaOCl 2.5% + Er,Cr:YSGG lasing (dried RC), (4) SP + Er,Cr:YSGG lasing (wet RC), and (5) NaOCl 2.5% + Er,Cr:YSGG lasing (wet RC). Groups 6 to 10 consisted of the same filled teeth with resected apices. Resection was performed after the first CFP measurement. CFP was used to assess minimum, mean flow, and maximum pore diameters after 48 h. Statistics were performed using nonparametric tests (P > 0.05). Additional three roots per group were submitted to SEM of the RC walls. TTL was observed in all groups without statistically significant differences between the different groups for minimum, mean, and maximum pore diameter (P > 0.05). In this study, the use of EDTA and/or Er,Cr:YSGG laser did not reduce through-and-through leakage in nonresected and resected roots. PMID:24696685

Independent from muscle power and balance performance, a creatinine clearance below 65 ml/min is a significant and independent risk factor for falls and fall-related fractures in elderly men and women diagnosed with osteoporosis.

PubMed

Dukas, L; Schacht, E; Runge, M

2010-07-01

We assessed in a cross-sectional study in elderly men and women with osteoporosis, the association between the creatinine clearance (CrCl) and the performance in different balance and muscle power and function tests and found that a decreasing creatinine clearance was significantly associated with lower balance and muscle power. To determine if a creatinine clearance of <65 ml/min is significantly associated with decreasing muscle power and balance and an increased risk for falls and fractures. We assessed in a cross-sectional-study in 1781 German osteoporotic patients, the association between the CrCl, the physical performance, and the number of falls and fractures. Controlling for age, gender, BMI, and osteoporosis treatment (fracture analysis only), a decreasing CrCl was associated with lower physical performance in the timed-up-and-go test (corr -0.2337, P < 0.0001), chair-rising test (corr -0.1706, P < 0.001), and tandem-stand test (corr 0.2193, P < 0.0001), and a CrCl of <65 ml/min was associated with a significantly higher risk for falls (47.7% vs. 36.2%, P = 0.0008) and fall-related fractures (33.1% vs. 22.9%, P = 0.0003) compared with a CrCl of >or=65 ml/min. In this study, we found a significant gender-independent correlation between decreasing CrCl and lower performance in balance and muscle power tests. Reduced muscle power and balance may therefore be involved in the low creatinine clearance associated increased risk for falls and fall-related fractures. Furthermore, we found that a CrCl <65 ml/min., independent from the performance in muscle power, muscle function, and balance tests, is a significant risk factor for falls and fractures.

IN SITU CR(VI) TREATMENT USING A FERROUS IRON-BASED REDUCTANT

EPA Science Inventory

Laboratory and field studies were conducted to evaluate the performance of a ferrous sulfate/ sodium hydrosulfite (dithionite) reductant blend in treating a hexavalent chromium (Cr(VI)) source area and Cr(VI) dissolved phase plume at a former industrial site in Charleston, South ...

Cognitive Reserve in Healthy Aging and Alzheimer's Disease: A Meta-Analysis of fMRI Studies.

PubMed

Colangeli, Stefano; Boccia, Maddalena; Verde, Paola; Guariglia, Paola; Bianchini, Filippo; Piccardi, Laura

2016-08-01

Cognitive reserve (CR) has been defined as the ability to optimize or maximize performance through differential recruitment of brain networks. In the present study, we aimed at providing evidence for a consistent brain network underpinning CR in healthy and pathological aging. To pursue this aim, we performed a coordinate-based meta-analysis of 17 functional magnetic resonance imaging studies on CR proxies in healthy aging, Alzheimer's disease (AD), and mild cognitive impairment (MCI). We found that different brain areas were associated with CR proxies in healthy and pathological aging. A wide network of areas, including medial and lateral frontal areas, that is, anterior cingulate cortex and dorsolateral prefrontal cortex, as well as precuneus, was associated with proxies of CR in healthy elderly patients. The CR proxies in patients with AD and amnesic-MCI were associated with activation in the anterior cingulate cortex. These results were discussed hypothesizing the existence of possible compensatory mechanisms in healthy and pathological aging. © The Author(s) 2016.

Enhancing the Oxidation Performance of Wrought Ni-Base Superalloy by Minor Additions of Active Elements

NASA Astrophysics Data System (ADS)

Tawancy, H. M.

2016-12-01

We show that the oxidation performance of Cr2O3-forming superalloy based upon the Ni-Cr-W system is significantly improved by the presence of minor concentrations of La, Si and Mn, which outweigh the detrimental effect of high W concentration in the alloy. Although Cr2O3 is known to transform into volatile CrO3 at temperatures ≥950 °C, the respective protection is extended to temperatures reaching 1150 °C, which has also been correlated with the beneficial effects of La, Si and Mn. During high-temperature oxidation, an inner protective La- and Si-modified layer of α-Cr2O3 in contact with the superalloy substrate is developed and shielded by an outermost layer of MnCr2O4. The distribution of La and Si in the inner oxide layer has been characterized down to the scale of transmission electron microscopy, and the possible mechanisms underlying their beneficial effects are elucidated.

A Study on Cognitive Radio Coexisting with Cellular Systems

NASA Astrophysics Data System (ADS)

Tandai, Tomoya; Horiguchi, Tomoya; Deguchi, Noritaka; Tomizawa, Takeshi; Tomioka, Tazuko

Cognitive Radios (CRs) are expected to perform more significant role in the view of efficient utilization of the spectrum resources in the future wireless communication networks. In this paper, a cognitive radio coexisting with cellular systems is proposed. In the case that a cellular system adopts Frequency Division Duplex (FDD) as a multiplexing scheme, the proposed CR terminals communicate in local area on uplink channels of the cellular system with transmission powers that don't interfere with base stations of the cellular system. Alternatively, in the case that a cellular system adopts Time Division Duplex (TDD), the CR terminals communicate on uplink slots of the cellular system. However if mobile terminals in the cellular system are near the CR network, uplink signals from the mobile terminals may interfere with the CR communications. In order to avoid interference from the mobile terminals, the CR terminal performs carrier sense during a beginning part of uplink slot, and only when the level of detected signal is below a threshold, then the CR terminal transmits a signal during the remained period of the uplink slot. In this paper, both the single carrier CR network that uses one frequency channel of the cellular system and the multicarrier CR network that uses multiple frequency channels of the cellular system are considered. The probabilities of successful CR communications, the average throughputs of the CR communications according to the positions of the CR network, and the interference levels from cognitive radio network to base stations of the cellular system are evaluated in the computer simulation then the effectiveness of the proposed network is clarified.

Application of advanced structure to multi-tone mask for FPD process

NASA Astrophysics Data System (ADS)

Song, Jin-Han; Jeong, Jin-Woong; Kim, Kyu-Sik; Jeong, Woo-Gun; Yun, Sang-Pil; Lee, Dong-Heok; Choi, Sang-Soo

2017-07-01

In accordance with improvement of FPD technology, masks such as phase shift mask (PSM) and multi-tone mask (MTM) for a particular purpose also have been developed. Above all, the MTM consisted of more than tri-tone transmittance has a substantial advantage which enables to reduce the number of mask demand in FPD fabrication process contrast to normal mask of two-tone transmittance.[1,2] A chromium (Cr)-based MTM (Typically top type) is being widely employed because of convenience of etch process caused by its only Cr-based structure consisted of Cr absorber layer and Cr half-tone layer. However, the top type of Cr-based MTM demands two Cr sputtering processes after each layer etching process and writing process. For this reason, a different material from the Cr-based MTM is required for reduction of mask fabrication time and cost. In this study, we evaluate a MTM which has a structure combined Cr with molybdenum silicide (MoSi) to resolve the issues mentioned above. The MoSi which is demonstrated by integrated circuit (IC) process is a suitable material for MTM evaluation. This structure could realize multi-transmittance in common with the Cr-based MTM. Moreover, it enables to reduce the number of sputtering process. We investigate a optimized structure upon consideration of productivity along with performance such as critical dimension (CD) variation and transmittance range of each structure. The transmittance is targeted at h-line wavelength (405 nm) in the evaluation. Compared with Cr-based MTM, the performances of all Cr-/MoSi-based MTMs are considered.

CuMn1.8O4 protective coatings on metallic interconnects for prevention of Cr-poisoning in solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Sun, Zhihao; Wang, Ruofan; Nikiforov, Alexey Y.; Gopalan, Srikanth; Pal, Uday B.; Basu, Soumendra N.

2018-02-01

Cr-poisoning of the cathodes due to the presence of metallic interconnects is detrimental to the performance of intermediate temperature solid oxide fuel cell stacks. Applying a protective coating on the interconnect is an effective solution to preventing Cr-poisoning. In this study, the application of a protective CuMn1.8O4 spinel coating is explored. Dense coatings are deposited on both metallic flat plates and meshes by electrophoretic deposition followed by thermal densification steps. The coating is found to be a mixture of Mn3O4 and cubic spinel phases at room temperature but is a pure cubic spinel phase between 750 °C and 850 °C. A reaction layer between the Cr2O3 scale at the coating/interconnect interface and CuMn1.8O4 coating is found to be a mixture of (Cu,Mn,Cr)3-xO4 cubic spinel phases with Cr-rich precipitates believed to be Cr2O3, indicating that the coating layer acts as a Cr getter. Solubility experiments show that 1 mol of the CuMn1.8O4 phase can getter at least 1.83 mol of Cr2O3 at 800 °C. Electrochemical testing of cells in the presence of coated interconnects show that the CuMn1.8O4 coating getters Cr effectively for 12 days at 800 °C, leading to no performance loss of the cell due to Cr-poisoning.

Meta-Analysis Comparing Complete Revascularization Versus Infarct-Related Only Strategies for Patients With ST-Segment Elevation Myocardial Infarction and Multivessel Coronary Artery Disease.

PubMed

Shah, Rahman; Berzingi, Chalak; Mumtaz, Mubashir; Jasper, John B; Goswami, Rohan; Morsy, Mohamed S; Ramanathan, Kodangudi B; Rao, Sunil V

2016-11-15

Several recent randomized controlled trials (RCTs) demonstrated better outcomes with multivessel complete revascularization (CR) than with infarct-related artery-only revascularization (IRA-OR) in patients with ST-segment elevation myocardial infarction. It is unclear whether CR should be performed during the index procedure (IP) at the time of primary percutaneous coronary intervention (PCI) or as a staged procedure (SP). Therefore, we performed a pairwise meta-analysis using a random-effects model and network meta-analysis using mixed-treatment comparison models to compare the efficacies of 3 revascularization strategies (IRA-OR, CR-IP, and CR-SP). Scientific databases and websites were searched to find RCTs. Data from 9 RCTs involving 2,176 patients were included. In mixed-comparison models, CR-IP decreased the risk of major adverse cardiac events (MACEs; odds ratio [OR] 0.36, 95% CI 0.25 to 0.54), recurrent myocardial infarction (MI; OR 0.50, 95% CI 0.24 to 0.91), revascularization (OR 0.24, 95% CI 0.15 to 0.38), and cardiovascular (CV) mortality (OR 0.44, 95% CI 0.20 to 0.87). However, only the rates of MACEs, MI, and CV mortality were lower with CR-SP than with IRA-OR. Similarly, in direct-comparison meta-analysis, the risk of MI was 66% lower with CR-IP than with IRA-OR, but this advantage was not seen with CR-SP. There were no differences in all-cause mortality between the 3 revascularization strategies. In conclusion, this meta-analysis shows that in patients with ST-segment elevation myocardial infarction and multivessel coronary artery disease, CR either during primary PCI or as an SP results in lower occurrences of MACE, revascularization, and CV mortality than IRA-OR. CR performed during primary PCI also results in lower rates of recurrent MI and seems the most efficacious revascularization strategy of the 3. Published by Elsevier Inc.

Cost and Performance Report: Introduction and Validation of Chromium-Free Consumables for Welding Stainless Steels. Version 2

DTIC Science & Technology

2015-04-01

hexavalent chromium in the welding fume of stainless steel . Welds of both Cr-free consumables met the performance objectives of 70,000 pounds per square...hexavalent chromium (Cr(VI)) in the welding fume of stainless steel . This project was developed in two stages: laboratory demonstration and field...consumables they are designed to replace. The measured Cr(VI) in the fume of the SMAW electrode when welding Type 304 stainless steel is virtually zero

3D Simulations of NIF Wetted Foam Experiments to Understand the Transition from 2D to 3D Implosion Behavior

NASA Astrophysics Data System (ADS)

Haines, Brian; Olson, Richard; Yi, Austin; Zylstra, Alex; Peterson, Robert; Bradley, Paul; Shah, Rahul; Wilson, Doug; Kline, John; Leeper, Ramon; Batha, Steve

2017-10-01

The high convergence ratio (CR) of layered Inertial Confinement Fusion capsule implosions contribute to high performance in 1D simulations yet make them more susceptible to hydrodynamic instabilities, contributing to the development of 3D flows. The wetted foam platform is an approach to hot spot ignition to achieve low-to-moderate convergence ratios in layered implosions on the NIF unobtainable using an ice layer. Detailed high-resolution modeling of these experiments in 2D and 3D, including all known asymmetries, demonstrates that 2D hydrodynamics explain capsule performance at CR 12 but become less suitable as the CR increases. Mechanisms for this behavior and detailed comparisons of simulations to experiments on NIF will be presented. To evaluate the tradeoff between increased instability and improved 1D performance, we present a full-scale wetted foam capsule design with 17

Uninvolved versus target muscle contraction during contract: relax proprioceptive neuromuscular facilitation stretching.

PubMed

Azevedo, Daniel Camara; Melo, Raphael Marques; Alves Corrêa, Ricardo Vidal; Chalmers, Gordon

2011-08-01

The purpose of this study was to compare the acute effect of the contract-relax (CR) stretching technique on knee active range of motion (ROM) using target muscle contraction or an uninvolved muscle contraction. pre-test post-test control experimental design. Clinical research laboratory. Sixty healthy men were randomly assigned to one of three groups. The Contract-Relax group (CR) performed a traditional hamstring CR stretch, the Modified Contract-Relax group (MCR) performed hamstring CR stretching using contraction of an uninvolved muscle distant from the target muscle, and the Control group (CG) did not stretch. Active knee extension test was performed before and after the stretching procedure. Two-way between-within analysis of variance (ANOVA) results showed a significant interaction between group and pre-test to post-test (p < 0.001). Post-hoc examination of individual groups showed no significant change in ROM for the CG (0.8°, p = 0.084), and a significant moderate increase in ROM for both the CR (7.0°, p < 0.001) and MCR (7.0°, p < 0.001) groups. ROM gain following a CR PNF procedure is the same whether the target stretching muscle is contracted, or an uninvolved muscle is contracted. Copyright © 2011 Elsevier Ltd. All rights reserved.

Post-synthetic modification of MIL-101(Cr) with pyridine for high-performance liquid chromatographic separation of tocopherols.

PubMed

Yang, Fang; Yang, Cheng-Xiong; Yan, Xiu-Ping

2015-05-01

Effective separation of tocopherols is challenging and significant due to their structural similarity and important biological role. Here we report the post-synthetic modification of metal-organic framework (MOF) MIL-101(Cr) with pyridine for high-performance liquid chromatographic (HPLC) separation of tocopherols. Baseline separation of four tocopherols was achieved on a pyridine-grafted MIL-101(Cr) packed column within 10 min using hexane/isopropanol (96:4, v/v) as the mobile phase at a flow rate of 0.5 mL min(-1). The pyridine-grafted MIL-101(Cr) packed column gave high column efficiency (85,000 plates m(-1) for δ-tocopherol) and good precision (0.2-0.3% for retention time, 1.8-3.4% for peak area, 2.6-2.7% for peak height), and also offered much better performance than unmodified MIL-101(Cr) and commercial amino-bonded silica packed column for HPLC separation of tocopherols. The results not only show the promising application of pyridine-grafted MIL-101(Cr) as a novel stationary phase for HPLC separation of tocopherols, but also reveal a facile post-modification of MOFs to expand the application of MOFs in separation sciences. Copyright © 2015 Elsevier B.V. All rights reserved.

Cognitive reserve moderates the association between functional network anti-correlations and memory in MCI.

PubMed

Franzmeier, Nicolai; Buerger, Katharina; Teipel, Stefan; Stern, Yaakov; Dichgans, Martin; Ewers, Michael

2017-02-01

Cognitive reserve (CR) shows protective effects on cognitive function in older adults. Here, we focused on the effects of CR at the functional network level. We assessed in patients with amnestic mild cognitive impairment (aMCI) whether higher CR moderates the association between low internetwork cross-talk on memory performance. In 2 independent aMCI samples (n = 76 and 93) and healthy controls (HC, n = 36), CR was assessed via years of education and intelligence (IQ). We focused on the anti-correlation between the dorsal attention network (DAN) and an anterior and posterior default mode network (DMN), assessed via sliding time window analysis of resting-state functional magnetic resonance imaging (fMRI). The DMN-DAN anti-correlation was numerically but not significantly lower in aMCI compared to HC. However, in aMCI, lower anterior DMN-DAN anti-correlation was associated with lower memory performance. This association was moderated by CR proxies, where the association between the internetwork anti-correlation and memory performance was alleviated at higher levels of education or IQ. In conclusion, lower DAN-DMN cross-talk is associated with lower memory in aMCI, where such effects are buffered by higher CR. Copyright © 2016 Elsevier Inc. All rights reserved.

Synergistic enhancement in photocatalytic performance of Ce (IV) and Cr (III) co-substituted magnetite nanoparticles loaded on reduced graphene oxide sheets.

PubMed

Rad, Tannaz Sadeghi; Khataee, Alireza; Rahim Pouran, Shima

2018-05-24

Effective utilization of visible-light by a photocatalyst is of great significance in photocatalytic processes. Herein, magnetite structure was modified by co-incorporation of Ce 4+ and Cr 3+ cations, and deposition on reduced graphene oxide sheets. The as-prepared Fe 2.8 Cr 0.2 O 4 #rGO and Fe 2.5 Cr 0.2 Ce 0.3 O 4 #rGO nanocomposites were characterized by XRD, SEM, X-ray Dot mapping, EDX, BET, DRS, XPS, FT-IR and VSM techniques and assessed for their photocatalytic performance under visible light irradiation for treatment of methylene blue. The results confirmed the central role of the incorporated Cr and Ce in improving the photocatalytic performance of magnetite through enhanced light harvesting, and the role of Ce 3+ /Ce 4+ redox pair, and rGO sheets in extending the life span of photo-induced e - /h + . Moreover, the influence of enhancers and scavengers were evaluated and oxidation path and generated byproducts were estimated. The results established the Fe 2.5 Cr 0.2 Ce 0.3 O 4 #rGO nanocomposite as a visible-light-driven photocatalyst for effective degradation of recalcitrant compounds. Copyright © 2018 Elsevier Inc. All rights reserved.

Synthesis of β-AgVO3 nanowires decorated with Ag2CrO4, with improved visible light photocatalytic performance

NASA Astrophysics Data System (ADS)

Ouyang, Qi; Li, Zhonghua; Liu, Jiawen

2018-05-01

Silver chromate‑silver vanadate (Ag2CrO4/β-AgVO3) heterojunction composites are synthesized through a facile precipitation process. The Ag2CrO4/β-AgVO3 hybrids obtained exhibit better photocatalytic activity in degradation of RhB than both pure Ag2CrO4 and β-AgVO3 under visible light irradiation. The 20 wt% Ag2CrO4/β-AgVO3 heterojunction possesses the best photocatalytic ability for degrading RhB: 24.4 times that of pristine β-AgVO3 nanowires and 3.2 times that of individual Ag2CrO4 particles. The phase of the nanocomposites was analyzed using x-ray diffraction as well as x-ray photoelectron spectroscopy. Their morphology was observed via scanning electron microscopy and transmission electron microscopy. The improvement in photocatalytic performance is chiefly ascribed to the synergies between Ag2CrO4/β-AgVO3 heterostructure, which can enhance the light absorbance ability and also accelerate the separation and transfer of photoinduced electrons and holes under visible light irradiation; this is also confirmed by UV–vis diffuse reflection spectrometry and fluorescence emission spectra.

Comparative Study of Chromium(VI) Removal from Simulated Industrial Wastewater with Ion Exchange Resins

NASA Astrophysics Data System (ADS)

Li, Xiaofan; Shi, Shaoyuan; Cao, Hongbin; Li, Yuping; Xu, Dongyao

2018-06-01

Ion exchange process is an alternative technique for removal of heavy metal ions from industrial wastewater. The main aim of this paper is to evaluate the performance of different ion exchange resins in removing Cr(VI) from wastewater. The effects of resin types and dosage, initial pH were examined systemically. The results showed that the performance of different resins had obvious difference for the removal of the Cr(VI) ions, in which the type of functional groups of the resin was the main factor. The SEM images indicated that the micro-morphology of resins before and after adsorption of the Cr(VI) presented a little difference. The EDS analysis showed that the adsorbed Cr(VI) was uniformly distributed at the surface of the resins with formation of oxygen-containing groups. The adsorption isotherms and kinetics of Cr(VI) by the different resins are also discussed.

High-Temperature Behavior of a NiCr-Coated T91 Boiler Steel in the Platen Superheater of Coal-Fired Boiler

NASA Astrophysics Data System (ADS)

Chatha, Sukhpal Singh; Sidhu, Hazoor S.; Sidhu, Buta S.

2013-06-01

Ni-20Cr coating was deposited on T91 boiler tube steel by high-velocity oxy-fuel (HVOF) process to enhance high-temperature oxidation resistance. High-temperature performance of bare, as well as HVOF-coated steel specimens was evaluated for 1500 h under in the platen superheater zone of coal-fired boiler, where the temperature was around 900 °C. Experiments were carried out for 15 cycles, each of 100-h duration followed by 1-h cooling at ambient temperature. The extent of degradation of the specimens was assessed by the thickness loss and depth of internal corrosion attack. Ni-20Cr-coated steel performed better than the uncoated steel in actual boiler environment. The improved degradation resistance of Ni-20Cr coating can be attributed to the presence of Cr2O3 in the top oxide scale and dense microstructure.

Energy transfer efficiency from Cr(3+) to Nd(3+) in solar-pumped laser using transparent Nd/Cr:Y(3)Al(5)O(12) ceramics.

PubMed

Hasegawa, Kazuo; Ichikawa, Tadashi; Mizuno, Shintaro; Takeda, Yasuhiko; Ito, Hiroshi; Ikesue, Akio; Motohiro, Tomoyoshi; Yamaga, Mitsuo

2015-06-01

We report energy transfer efficiency from Cr³⁺ to Nd³⁺ in Nd (1.0 at.%)/Cr (0.4 at.%) co-doped Y₃Al₅O₁₂ (YAG) transparent ceramics in the laser oscillation states. The laser oscillation has performed using two pumping lasers operating at 808 nm and 561 nm; the former pumps Nd³⁺ directly to create the 1064 nm laser oscillation, whereas the latter assists the performance via Cr³⁺ absorption and sequential energy transfer to Nd³⁺. From the laser output power properties and laser mode analysis, the energy transfer efficiency was determined to be around 65%, which is close to that obtained from the spontaneous Nd³⁺ emission.

Performance and metabolic responses of Holstein calves to supplemental chromium in colostrum and milk.

PubMed

Ghorbani, A; Sadri, H; Alizadeh, A R; Bruckmaier, R M

2012-10-01

Twenty-two newborn Holstein female calves (BW = 39.7 ± 0.40 kg) were used to investigate the effects of chromium-l-methionine (Cr-Met) supplementation of colostrum for 3d after birth and mature milk up to wk 8 on feed intake, growth performance, health status, and metabolic and endocrine traits. Calves were randomly assigned to 2 groups, each consisting of 11 animals: 1) control and 2) 0.03 mg of supplemental Cr/kg of BW(0.75). Body weight, height at withers, and hearth girth were measured weekly. Dry matter intake, rectal temperature, fecal score, and respiratory score were recorded daily. Blood samples were collected at 12, 24, and 72 h after birth, and then every week up to 8 wk. Chromium did not affect mean body weight, dry matter intake, and withers height, but it increased hearth girth and average daily gain, tended to increase final BW, and decreased feed conversion ratio. Respiration rate increased and fecal score decreased with Cr, and rectal temperature tended to decrease with Cr. No Cr × time interactions were observed for performance and health status results except for fecal score. Blood glucose, insulin, insulin-to-glucose ratio, insulin-like growth factor-I, total protein, and triiodothyronine were not affected, whereas blood β-hydroxybutyrate, nonesterified fatty acids, cholesterol, cortisol, and thyroxin were affected by Cr supplementation. Supplemental Cr-Met decreased blood β-hydroxybutyrate at 72 h and in wk 1, 3, 4, 5, and 6 and decreased blood nonesterified fatty acids at 12h and in wk 3, 4, and 5 after birth. Blood cholesterol decreased in all sampling times, except for 12h and wk 7. Chromium decreased blood cortisol at 24h and in wk 2, 4, and 8. In conclusion, the present results demonstrate the beneficial effects of colostrum and milk supplementation with Cr to improve the performance and metabolic status of newborn calves. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Application of high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) for determination of chromium compounds in the air at the workplace.

PubMed

Stanislawska, Magdalena; Janasik, Beata; Wasowicz, Wojciech

2013-12-15

The toxicity and bioavailability of chromium species are highly dependable on the form or species, therefore determination of total chromium is insufficient for a complete toxicological evaluation and risk assessment. An analytical method for determination of soluble and insoluble Cr (III) and Cr (VI) compounds in welding fume at workplace air has been developed. The total chromium (Cr) was determined by using quadruple inductively coupled plasma mass spectrometry (ICP-MS) equipped with a dynamic reaction cell (DRC(®)). Soluble trivalent and hexavalent chromium compounds were determined by high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). A high-speed, reversed-phase CR C8 column (PerkinElmer, Inc., Shelton, CT, USA) was used for the speciation of soluble Cr (III) and soluble Cr (VI). The separation was accomplished by interaction of the chromium species with the different components of the mobile phase. Cr (III) formed a complex with EDTA, i.e. retained on the column, while Cr (VI) existed in the solutions as dichromate. Alkaline extraction (2% KOH and 3% Na2CO3) and anion exchange column (PRP-X100, PEEK, Hamilton) were used for the separation of the total Cr (VI). The results of the determination of Cr (VI) were confirmed by the analysis of the certified reference material BCR CRM 545 (Cr (VI) in welding dust). The results obtained for the certified material (40.2±0.6 g kg(-1)) and the values recorded in the examined samples (40.7±0.6 g kg(-1)) were highly consistent. This analytical method was applied for the determination of chromium in the samples in the workplace air collected onto glass (Whatman, Ø 37 mm) and membrane filters (Sartorius, 0.8 μm, Ø 37 mm). High performance liquid chromatography with inductively coupled plasma mass spectrometry is a remarkably powerful and versatile technique for determination of chromium species in welding fume at workplace air. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.

Double Threshold Energy Detection Based Cooperative Spectrum Sensing for Cognitive Radio Networks with QoS Guarantee

NASA Astrophysics Data System (ADS)

Hu, Hang; Yu, Hong; Zhang, Yongzhi

2013-03-01

Cooperative spectrum sensing, which can greatly improve the ability of discovering the spectrum opportunities, is regarded as an enabling mechanism for cognitive radio (CR) networks. In this paper, we employ a double threshold detection method in energy detector to perform spectrum sensing, only the CR users with reliable sensing information are allowed to transmit one bit local decision to the fusion center. Simulation results will show that our proposed double threshold detection method could not only improve the sensing performance but also save the bandwidth of the reporting channel compared with the conventional detection method with one threshold. By weighting the sensing performance and the consumption of system resources in a utility function that is maximized with respect to the number of CR users, it has been shown that the optimal number of CR users is related to the price of these Quality-of-Service (QoS) requirements.

Creatine Loading, Resistance Exercise Performance, and Muscle Mechanics.

ERIC Educational Resources Information Center

Stevenson, Scott W.; Dudley, Gary A.

2001-01-01

Examined whether creatine (CR) monohydrate loading would alter resistance exercise performance, isometric strength, or in vivo contractile properties of the quadriceps femoris muscle compared with placebo loading in resistance-trained athletes. Overall, CR loading did not provide an ergogenic benefit for the unilateral dynamic knee extension…

In-situ XAFS study for calcination process of Cr catalyst supported on γ-Al2O3 and SiO2

NASA Astrophysics Data System (ADS)

Watanabe, T.; Ikeda, K.; Katayama, M.; Inada, Y.

2016-05-01

The catalytic performance is largely affected by the oxidation state of supported Cr species, and its control changes the activity of Cr catalysts and the selectivity of products. In this study, the calcination process of the supported Cr catalysts on γ-Al2O3 and SiO2 was investigated by in-situ XAFS spectroscopy. The hydrate species was first supported by the impregnation method and was converted to CrO3 via Cr2O3 during the calcination process on both supporting materials. It was found that the temperature to complete the oxidation from Cr2O3 to CrO3 on SiO2 was higher than that on γ-Al2O3. The similarity of the interatomic distance between the surface oxygen atoms of the intermediate Cr2O3 species to that of SiO2 contributes to the stabilization of Cr2O3 on SiO2 during the calcination process.

General Slowing and Education Mediate Task Switching Performance Across the Life-Span

PubMed Central

Moretti, Luca; Semenza, Carlo; Vallesi, Antonino

2018-01-01

Objective: This study considered the potential role of both protective factors (cognitive reserve, CR) and adverse ones (general slowing) in modulating cognitive flexibility in the adult life-span. Method: Ninety-eight individuals performed a task-switching (TS) paradigm in which we adopted a manipulation concerning the timing between the cue and the target. Working memory demands were minimized by using transparent cues. Additionally, indices of cognitive integrity, depression, processing speed and different CR dimensions were collected and used in linear models accounting for TS performance under the different time constraints. Results: The main results showed similar mixing costs and higher switching costs in older adults, with an overall age-dependent effect of general slowing on these costs. The link between processing speed and TS performance was attenuated when participants had more time to prepare. Among the different CR indices, formal education only was associated with reduced switch costs under time pressure. Discussion: Even though CR is often operationalized as a unitary construct, the present research confirms the benefits of using tools designed to distinguish between different CR dimensions. Furthermore, our results provide empirical support to the assumption that processing speed influence on executive performance depends on time constraints. Finally, it is suggested that whether age differences appear in terms of switch or mixing costs depends on working memory demands (which were low in our tasks with transparent cues). PMID:29780341

A simple measure of cognitive reserve is relevant for cognitive performance in MS patients.

PubMed

Della Corte, Marida; Santangelo, Gabriella; Bisecco, Alvino; Sacco, Rosaria; Siciliano, Mattia; d'Ambrosio, Alessandro; Docimo, Renato; Cuomo, Teresa; Lavorgna, Luigi; Bonavita, Simona; Tedeschi, Gioacchino; Gallo, Antonio

2018-05-04

Cognitive reserve (CR) contributes to preserve cognition despite brain damage. This theory has been applied to multiple sclerosis (MS) to explain the partial relationship between cognition and MRI markers of brain pathology. Our aim was to determine the relationship between two measures of CR and cognition in MS. One hundred and forty-seven MS patients were enrolled. Cognition was assessed using the Rao's Brief Repeatable Battery and the Stroop Test. CR was measured as the vocabulary subtest of the WAIS-R score (VOC) and the number of years of formal education (EDU). Regression analysis included raw score data on each neuropsychological (NP) test as dependent variables and demographic/clinical parameters, VOC, and EDU as independent predictors. A binary logistic regression analysis including clinical/CR parameters as covariates and absence/presence of cognitive deficits as dependent variables was performed too. VOC, but not EDU, was strongly correlated with performances at all ten NP tests. EDU was correlated with executive performances. The binary logistic regression showed that only the Expanded Disability Status Scale (EDSS) and VOC were independently correlated with the presence/absence of CD. The lower the VOC and/or the higher the EDSS, the higher the frequency of CD. In conclusion, our study supports the relevance of CR in subtending cognitive performances and the presence of CD in MS patients.

The solvent at antigen-binding site regulated C3d-CR2 interactions through the C-terminal tail of C3d at different ion strengths: insights from molecular dynamics simulation.

PubMed

Zhang, Yan; Guo, Jingjing; Li, Lanlan; Liu, Xuewei; Yao, Xiaojun; Liu, Huanxiang

2016-10-01

The interactions of complement receptor 2 (CR2) and the degradation fragment C3d of complement component C3 play important links between the innate and adaptive immune systems. Due to the importance of C3d-CR2 interaction in the design of vaccines and inhibitors, a number of studies have been performed to investigate C3d-CR2 interaction. Many studies have indicated C3d-CR2 interactions are ionic strength-dependent. To investigate the molecular mechanism of C3d-CR2 interaction and the origin of effects of ionic strength, molecular dynamics simulations for C3d-CR2 complex together with the energetic and structural analysis were performed. Our results revealed the increased interactions between charged protein and ions weaken C3d-CR2 association, as ionic strengths increase. Moreover, ion strengths have similar effects on antigen-binding site and CR2 binding site. Meanwhile, Ala17 and Gln20 will transform between the activated and non-activated states mediated by His133 and Glu135 at different ion strengths. Our results reveal the origins of the effects of ionic strengths on C3d-CR2 interactions are due to the changes of water, ion occupancies and distributions. This study uncovers the origin of the effect of ionic strength on C3d-CR2 interaction and deepens the understanding of the molecular mechanism of their interaction, which is valuable for the design of vaccines and small molecule inhibitors. Copyright © 2016 Elsevier B.V. All rights reserved.

High-intensity interval training and calorie restriction promote remodeling of glucose and lipid metabolism in diet-induced obesity.

PubMed

Davis, Rachel A H; Halbrooks, Jacob E; Watkins, Emily E; Fisher, Gordon; Hunter, Gary R; Nagy, Tim R; Plaisance, Eric P

2017-08-01

Calorie restriction (CR) decreases adiposity, but the magnitude and defense of weight loss is less than predicted due to reductions in total daily energy expenditure (TEE). The purpose of the current investigation was to determine whether high-intensity interval training (HIIT) would increase markers of sympathetic activation in white adipose tissue (WAT) and rescue CR-mediated reductions in EE to a greater extent than moderate-intensity aerobic exercise training (MIT). Thirty-two 5-wk-old male C57BL/6J mice were placed on ad libitum HFD for 11 wk, followed by randomization to one of four groups ( n = 8/group) for an additional 15 wk: 1 ) CON (remain on HFD), 2 ) CR (25% lower energy intake), 3 ) CR + HIIT (25% energy deficit created by 12.5% CR and 12.5% EE through HIIT), and 4 ) CR + MIT (25% energy deficit created by 12.5% CR and 12.5% EE through MIT). Markers of adipose thermogenesis ( Ucp1 , Prdm16 , Dio2 , and Fgf21 ) were unchanged in either exercise group in inguinal or epididymal WAT, whereas CR + HIIT decreased Ucp1 expression in retroperitoneal WAT and brown adipose tissue. HIIT rescued CR-mediated reductions in lean body mass (LBM) and resting energy expenditure (REE), and both were associated with improvements in glucose/insulin tolerance. Improvements in glucose metabolism in the CR + HIIT group appear to be linked to a molecular signature that enhances glucose and lipid storage in skeletal muscle. Exercise performed at either moderate or high intensity does not increase markers of adipose thermogenesis when performed in the presence of CR but remodels skeletal muscle metabolic and thermogenic capacity. Copyright © 2017 the American Physiological Society.

Selenium-methionine and chromium-methionine supplementation of sheep around parturition: impacts on dam and offspring performance.

PubMed

Mousaie, Amir; Valizadeh, Reza; Chamsaz, Mahmoud

2017-04-01

To examine the effects of maternal energy restriction along with selenium-methionine (Se-Met) and chromium-methionine (Cr-Met) supplementation on performance of pregnant sheep and their offspring, the following treatments were allotted randomly to 40 multiparous Baluchi ewes (53.9 ± 1.15 kg of body weight [BW]) from 5 weeks prior to 5 weeks after parturition: (1) Control diet (60% and 100% of NRC energy requirements in pre- and post-partum, respectively); (2) Control diet plus 5 mg Se-Met/kg dry matter (DM); (3) Control diet plus 3 mg Cr-Met/kg DM and (4) Control diet plus 5 mg Se-Met and 3 mg Cr-Met/kg DM (Se-Cr-Met) of concentrate diet. The results indicated that Cr-Met alone or in combination with Se-Met increased average DM intake of ewes. In addition, Group Cr-Met had higher average BW than the Control (p < 0.05). Se-Met and/or Cr-Met supplementation led to decreased average serum cholesterol of the ewes (p < 0.05). Groups Cr-Met and Se-Cr-Met displayed decreased average serum malondialdehyde compared to the Control (p < 0.05). At 24 h post-partum, Group Se-Cr-Met had a greater serum Se content than the Control (p = 0.006). Compared with the Control, the Se concentration in milk was significantly increased from 30 to 138 µg/l and 197 µg/l in Groups Se-Met and Se-Cr-Met, respectively (p < 0.01), which proved that Se-Met supplementation can increase the Se concentration of ewe milk. Furthermore, feeding Cr-Met may attenuate BW loss post-partum and Se-Met and/or Cr-Met supplements may ameliorate oxidative stress condition in ewes around parturition.

Low Cryptococcus Antigen Titers as Determined by Lateral Flow Assay Should Be Interpreted Cautiously in Patients without Prior Diagnosis of Cryptococcal Infection.

PubMed

Dubbels, Marie; Granger, Dane; Theel, Elitza S

2017-08-01

Detection of Cryptococcus antigen (CrAg) is invaluable for establishing cryptococcal disease. Multiple different methods for CrAg detection are available, including a lateral flow assay (LFA). Despite excellent performance of the CrAg LFA, we have observed multiple cases of low-titer (≤1:5) positive CrAg LFA results in patients for whom cryptococcosis was ultimately excluded. To investigate the accuracy of low-titer positive CrAg LFA results, we performed chart reviews for all patients with positive CrAg LFA results between June 2014 and December 2016. During this period, serum and/or cerebrospinal fluid (CSF) samples from 3,969 patients were tested with the CrAg LFA, and 55 patients (1.5%) tested positive. Thirty-eight of those patients lacked a history of cryptococcal disease and were the focus of this study. Fungal culture or histopathology confirmed Cryptococcus infection for 20 patients (52.6%), and CrAg LFA titers in serum and CSF samples ranged from 1:5 to ≥1:2,560. For the 18 patients (47.4%) without culture or histopathological confirmation, the CrAg LFA results were considered true-positive results for 5 patients (titer range, 1:10 to ≥1:2,560), due to clinical improvement with targeted therapy and decreasing CrAg LFA titers. The remaining 13 patients had CrAg LFA titers of 1:2 ( n = 11) or 1:5 ( n = 2) and were ultimately diagnosed with an alternative condition ( n = 11) or began therapy for possible cryptococcosis without improvement ( n = 2), leading to an overall CrAg LFA false-positive rate of 34%. We recommend careful clinical correlation prior to establishing a diagnosis of cryptococcal infection for patients with first-time positive CrAg LFA titers of 1:2. Copyright © 2017 American Society for Microbiology.

Computer-aided cognitive rehabilitation improves cognitive performances and induces brain functional connectivity changes in relapsing remitting multiple sclerosis patients: an exploratory study.

PubMed

Bonavita, S; Sacco, R; Della Corte, M; Esposito, S; Sparaco, M; d'Ambrosio, A; Docimo, R; Bisecco, A; Lavorgna, L; Corbo, D; Cirillo, S; Gallo, A; Esposito, F; Tedeschi, G

2015-01-01

To better understand the effects of short-term computer-based cognitive rehabilitation (cCR) on cognitive performances and default mode network (DMN) intrinsic functional connectivity (FC) in cognitively impaired relapsing remitting (RR) multiple sclerosis (MS) patients. Eighteen cognitively impaired RRMS patients underwent neuropsychological evaluation by the Rao's brief repeatable battery and resting-state functional magnetic resonance imaging to evaluate FC of the DMN before and after a short-term (8 weeks, twice a week) cCR. A control group of 14 cognitively impaired RRMS patients was assigned to an aspecific cognitive training (aCT), and underwent the same study protocol. Correlations between DMN and cognitive performances were also tested. After cCR, there was a significant improvement of the following tests: SDMT (p < 0.01), PASAT 3" (p < 0.00), PASAT 2" (p < 0.03), SRT-D (p < 0.02), and 10/36 SPART-D (p < 0.04); as well as a significant increase of the FC of the DMN in the posterior cingulate cortex (PCC) and bilateral inferior parietal cortex (IPC). After cCR, a significant negative correlation between Stroop Color-Word Interference Test and FC in the PCC emerged. After aCT, the control group did not show any significant effect either on FC or neuropsychological tests. No significant differences were found in brain volumes and lesion load in both groups when comparing data acquired at baseline and after cCR or aCT. In cognitively impaired RRMS patients, cCR improves cognitive performances (i.e., processing speed and visual and verbal sustained memory), and increases FC in the PCC and IPC of the DMN. This exploratory study suggests that cCR may induce adaptive cortical reorganization favoring better cognitive performances, thus strengthening the value of cognitive exercise in the general perspective of building either cognitive or brain reserve.

Assessment of low-contrast detectability for compressed digital chest images

NASA Astrophysics Data System (ADS)

Cook, Larry T.; Insana, Michael F.; McFadden, Michael A.; Hall, Timothy J.; Cox, Glendon G.

1994-04-01

The ability of human observers to detect low-contrast targets in screen-film (SF) images, computed radiographic (CR) images, and compressed CR images was measured using contrast detail (CD) analysis. The results of these studies were used to design a two- alternative forced-choice (2AFC) experiment to investigate the detectability of nodules in adult chest radiographs. CD curves for a common screen-film system were compared with CR images compressed up to 125:1. Data from clinical chest exams were used to define a CD region of clinical interest that sufficiently challenged the observer. From that data, simulated lesions were introduced into 100 normal CR chest films, and forced-choice observer performance studies were performed. CR images were compressed using a full-frame discrete cosine transform (FDCT) technique, where the 2D Fourier space was divided into four areas of different quantization depending on the cumulative power spectrum (energy) of each image. The characteristic curve of the CR images was adjusted so that optical densities matched those of the SF system. The CD curves for SF and uncompressed CR systems were statistically equivalent. The slope of the CD curve for each was - 1.0 as predicted by the Rose model. There was a significant degradation in detection found for CR images compressed to 125:1. Furthermore, contrast-detail analysis demonstrated that many pulmonary nodules encountered in clinical practice are significantly above the average observer threshold for detection. We designed a 2AFC observer study using simulated 1-cm lesions introduced into normal CR chest radiographs. Detectability was reduced for all compressed CR radiographs.

Occurrence and Speciation of Polymeric Chromium(III), Monomeric Chromium(III) and Chromium(VI) in Environmental Samples

PubMed Central

HU, LIGANG; CAI, YONG; JIANG, GUIBIN

2016-01-01

Laboratory experiments suggest that polymeric Cr(III) could exist in aqueous solution for a relative long period of time. However, the occurrence of polymeric Cr(III) has not been reported in environmental media due partially to the lack of method for speciating polymeric Cr. We observed an unknown Cr species during the course of study on speciation of Cr in the leachates of chromated-copper-arsenate (CCA)-treated wood. Efforts were made to identify structure of the unknown Cr species. Considering the forms of Cr existed in the CCA-treated woods, we mainly focused our efforts to determine if the unknown species were polymeric Cr(III), complex of Cr/As or complex of Cr with dissolved organic matter (DOM). In order to evaluate whether polymeric Cr(III) largely exist in wood leachates, high performance liquid chromatography coupled with inductively coupled mass spectrometry (HPLC-ICPMS was used) for simultaneous speciation of monomeric Cr(III), polymeric Cr(III), and Cr(VI). In addition to wood leachates where polymeric Cr (III) ranged from 39.1 to 67.4 %, occurrence of the unknown Cr species in other environmental matrices, including surface waters, tap and waste waters, was also investigated. It was found that polymeric Cr(III) could exist in environmental samples containing μg/L level of Cr, at a level up to 60% of total Cr, suggesting that polymeric Cr(III) could significantly exist in natural environments. Failure in quantifying polymeric Cr(III) would lead to the underestimation of total Cr and bias in Cr speciation. The environmental implication of the presence of polymeric Cr(III) species in the environment deserves further study. PMID:27156211

A brief opportunity to run does not function as a reinforcer for mice selected for high daily wheel-running rates.

PubMed

Belke, Terry W; Garland, Theodore

2007-09-01

Mice from replicate lines, selectively bred based on high daily wheel-running rates, run more total revolutions and at higher average speeds than do mice from nonselected control lines. Based on this difference it was assumed that selected mice would find the opportunity to run in a wheel a more efficacious consequence. To assess this assumption within an operant paradigm, mice must be trained to make a response to produce the opportunity to run as a consequence. In the present study an autoshaping procedure was used to compare the acquisition of lever pressing reinforced by the opportunity to run for a brief opportunity (i.e., 90 s) between selected and control mice and then, using an operant procedure, the effect of the duration of the opportunity to run on lever pressing was assessed by varying reinforcer duration over values of 90 s, 30 min, and 90 s. The reinforcement schedule was a ratio schedule (FR 1 or VR 3). Results from the autoshaping phase showed that more control mice met a criterion of responses on 50% of trials. During the operant phase, when reinforcer duration was 90 s, almost all control, but few selected mice completed a session of 20 reinforcers; however, when reinforcer duration was increased to 30 min almost all selected and control mice completed a session of 20 reinforcers. Taken together, these results suggest that selective breeding based on wheel-running rates over 24 hr may have altered the motivational system in a way that reduces the reinforcing value of shorter running durations. The implications of this finding for these mice as a model for attention deficit hyperactivity disorder (ADHD) are discussed. It also is proposed that there may be an inherent trade-off in the motivational system for activities of short versus long duration.

A Brief Opportunity to Run Does Not Function as a Reinforcer for Mice Selected for High Daily Wheel-running Rates

PubMed Central

Belke, Terry W; GarlandJr, Theodore

2007-01-01

Mice from replicate lines, selectively bred based on high daily wheel-running rates, run more total revolutions and at higher average speeds than do mice from nonselected control lines. Based on this difference it was assumed that selected mice would find the opportunity to run in a wheel a more efficacious consequence. To assess this assumption within an operant paradigm, mice must be trained to make a response to produce the opportunity to run as a consequence. In the present study an autoshaping procedure was used to compare the acquisition of lever pressing reinforced by the opportunity to run for a brief opportunity (i.e., 90 s) between selected and control mice and then, using an operant procedure, the effect of the duration of the opportunity to run on lever pressing was assessed by varying reinforcer duration over values of 90 s, 30 min, and 90 s. The reinforcement schedule was a ratio schedule (FR 1 or VR 3). Results from the autoshaping phase showed that more control mice met a criterion of responses on 50% of trials. During the operant phase, when reinforcer duration was 90 s, almost all control, but few selected mice completed a session of 20 reinforcers; however, when reinforcer duration was increased to 30 min almost all selected and control mice completed a session of 20 reinforcers. Taken together, these results suggest that selective breeding based on wheel-running rates over 24 hr may have altered the motivational system in a way that reduces the reinforcing value of shorter running durations. The implications of this finding for these mice as a model for attention deficit hyperactivity disorder (ADHD) are discussed. It also is proposed that there may be an inherent trade-off in the motivational system for activities of short versus long duration. PMID:17970415

Tianeptine: 5-HT uptake sites and 5-HT(1-7) receptors modulate memory formation in an autoshaping Pavlovian/instrumental task.

PubMed

Meneses, Alfredo

2002-05-01

Recent studies using invertebrate and mammal species have revealed that, endogenous serotonin (5-hydroxytryptamine, 5-HT) modulates cognitive processes, particularly learning and memory, though, at present, it is unclear the manner, where, and how long 5-HT systems are involved. Hence in this work, an attempt was made to study the effects of 5-HT endogenous on memory formation, using a 5-HT uptake facilitator (tianeptine) and, selective 5-HT(1-7) receptor antagonists to determine whether 5-HT uptake sites and which 5-HT receptors are involved, respectively. Results showed that post-training tianeptine injection enhanced memory consolidation in an autoshaping Pavlovian/instrumental learning task, which has been useful to detect changes on memory formation elicited by drugs or aging. On interaction experiments, ketanserin (5-HT(1D/2A/2C) antagonist) slightly enhanced tianeptine effects, while WAY 100635 (5-HT(1A) antagonist), SB-224289 (5-HT(1B) inverse agonist), SB-200646 (5-HT(2B/2C) antagonist), ondansetron (5-HT(3) antagonist), GR 127487 (5-HT(4) antagonist), Ro 04-6790 (5-HT(6) antagonist), DR 4004 (5-HT(7) antagonist), or fluoxetine (an inhibitor of 5-HT reuptake) blocked the facilitatory tianeptine effect. Notably, together tianeptine and Ro 04-6790 impaired learning consolidation. Moreover, 5-HT depletion completely reversed the tianeptine effect. Tianeptine also normalized an impaired memory elicited by scopolamine (an antimuscarinic) or dizocilpine (non-competitive glutamatergic antagonist), while partially reversed that induced by TFMPP (5-HT(1B/1D/2A-2C/7) agonist/antagonist). Finally, tianeptine-fluoxetine coadministration had no effect on learning consolidation; nevertheless, administration of an acetylcholinesterase inhibitor, phenserine, potentiated subeffective tianeptine or fluoxetine doses. Collectively, these data confirmed that endogenously 5-HT modulates, via uptake sites and 5-HT(1-7) receptors, memory consolidation, and are consistent with the emerging notion that 5-HT plays a key role on memory formation.

Application of x-ray absorption fine structure (XAFS) to local-order analysis in Fe-Cr maghemite-like materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montero-Cabrera, M. E., E-mail: elena.montero@cimav.edu.mx; Fuentes-Cobas, L. E.; Macías-Ríos, E.

2015-07-23

The maghemite-like oxide system γ-Fe{sub 2-x}Cr{sub x}O{sub 3} (x=0.75, 1 and 1.25) was studied by X-ray absorption fine structure (XAFS) and by synchrotron radiation X-ray diffraction (XRD). Measurements were performed at the Stanford Synchrotron Radiation Lightsource at room temperature, at beamlines 2-1, 2-3 and 4-3. High-resolution XRD patterns were processed by means of the Rietveld method. In cases of atoms being neighbors in the Periodic Table, the order/disorder degree of the considered solutions is indiscernible by “normal” (absence of “anomalous scattering”) diffraction experiments. Thus, maghemite-like materials were investigated by XAFS in both Fe and Cr K-edges to clarify, via short-rangemore » structure characterization, the local ordering of the investigated system. Athena and Artemis graphic user interfaces for IFEFFIT and FEFF8.4 codes were employed for XAFS spectra interpretation. Pre-edge decomposition and theoretical modeling of X-ray absorption near edge structure (XANES) transitions were performed. By analysis of the Cr K-edge XANES, it has been confirmed that Cr is located in an octahedral environment. Fitting of the extended X-ray absorption fine structure (EXAFS) spectra was performed under the consideration that the central atom of Fe is allowed to occupy octa- and tetrahedral positions, while Cr occupies only octahedral ones. Coordination number of neighboring atoms, interatomic distances and their quadratic deviation average were determined for x=1, by fitting simultaneously the EXAFS spectra of both Fe and Cr K-edges. The results of fitting the experimental spectra with theoretical standards showed that the cation vacancies tend to follow a regular pattern within the structure of the iron-chromium maghemite (FeCrO{sub 3})« less

Effects of Supplemental Chromium Source and Concentration on Growth, Carcass Characteristics, and Serum Lipid Parameters of Broilers Reared Under Normal Conditions.

PubMed

Zheng, Cancai; Huang, Yanling; Xiao, Fang; Lin, Xi; Lloyd, Karen

2016-02-01

An experiment was conducted to investigate the effects of dietary chromium (Cr) source and concentration on growth performance, carcass traits, and some serum lipid parameters of broilers under normal rearing conditions for 42 days. A total of 252 1-day-old Cobb 500 commercial female broilers were randomly allotted by body weight (BW) to one of six replicate cages (six broilers per cage) for each of seven treatments in a completely randomized design involved in a 2 × 3 factorial arrangement of treatments with three Cr sources (Cr propionate (CrPro), Cr picolinate (CrPic), Cr chloride (CrCl3)) and two concentrations of added Cr (0.4 and 2.0 mg of Cr/kg) plus a Cr-unsupplemented control diet. The results showed that dietary Cr supplementation tended to increase the breast muscle percentage compared with the Cr-unsupplemented control group (P = 0.0784), while Cr from CrPic tended to have higher breast muscle percentage compared with Cr from CrCl3 (P = 0.0881). Chromium from CrPic also tended to increase the breast intramuscular fat (IMF) compared with Cr from CrCl3 (P = 0.0648). In addition, supplementation of 0.4 mg/kg Cr tended to decrease low-density lipoprotein cholesterol (LDL-C) (P = 0.0614). Compared with the control group, broilers fed Cr-supplemented diets had higher triglyceride (TG) (P = 0.0129) regardless of Cr source and Cr concentration. Chromium from CrPro and CrPic had lower total cholesterol (TC) compared with Cr from CrCl3 (P = 0.0220). These results indicate that dietary supplementation of Cr has effects on carcass characteristics and serum lipid parameters of broilers under normal rearing conditions, while supplementation of organic Cr can improve carcass characteristics and reduce the cholesterol content in serum.

High temperature wear performance of HVOF-sprayed Cr3C2-WC-NiCoCrMo and Cr3C2-NiCr hardmetal coatings

NASA Astrophysics Data System (ADS)

Zhou, Wuxi; Zhou, Kesong; Li, Yuxi; Deng, Chunming; Zeng, Keli

2017-09-01

A novel Cr3C2-WC-NiCoCrMo and commercial Cr3C2-NiCr thermal spray-grade powders with particle size of -45 + 15 μm were prepared by an agglomeration and sintering process. Cr3C2-WC-NiCoCrMo and Cr3C2-NiCr coatings were deposited by high velocity oxygen fuel (HVOF) spraying. The fundamental properties of both coatings were evaluated and friction wear test against Al2O3 counterbodies of both coatings at high temperatures (450 °C, 550 °C, 650 °C) were carried out ball-on-disk high temperature tribometer. All specimens were characterized by optical microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) and 3D non-contact surface mapping profiler. The results have shown that the Cr3C2-WC-NiCoCrMo coating exhibited lower porosity, higher micro-hardness compared to the Cr3C2-NiCr coating. The Cr3C2-WC-NiCoCrMo coating also exhibited better wear resistance and higher friction coefficient compared to the Cr3C2-NiCr coating when sliding against the Al2O3 counterpart. Wear rates of both coatings increased with raising temperature. Both coatings experienced abrasive wear; hard phase particles (WC and Cr3C2) with different sizes, distributed in the matrix phase, will effectively improve the resistance against wear at high temperatures.

BISON Fuel Performance Analysis of FeCrAl cladding with updated properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sweet, Ryan; George, Nathan M.; Terrani, Kurt A.

2016-08-30

In order to improve the accident tolerance of light water reactor (LWR) fuel, alternative cladding materials have been proposed to replace zirconium (Zr)-based alloys. Of these materials, there is a particular focus on iron-chromium-aluminum (FeCrAl) alloys due to much slower oxidation kinetics in high-temperature steam than Zr-alloys. This should decrease the energy release due to oxidation and allow the cladding to remain integral longer in the presence of high temperature steam, making accident mitigation more likely. As a continuation of the development for these alloys, suitability for normal operation must also be demonstrated. This research is focused on modeling themore » integral thermo-mechanical performance of FeCrAl-cladded fuel during normal reactor operation. Preliminary analysis has been performed to assess FeCrAl alloys (namely Alkrothal 720 and APMT) as a suitable fuel cladding replacement for Zr-alloys, using the MOOSE-based, finite-element fuel performance code BISON and the best available thermal-mechanical and irradiation-induced constitutive properties. These simulations identify the effects of the mechanical-stress and irradiation response of FeCrAl, and provide a comparison with Zr-alloys. In comparing these clad materials, fuel rods have been simulated for normal reactor operation and simple steady-state operation. Normal reactor operating conditions target the cladding performance over the rod lifetime (~4 cycles) for the highest-power rod in the highest-power fuel assembly under reactor power maneuvering. The power histories and axial temperature profiles input into BISON were generated from a neutronics study on full-core reactivity equivalence for FeCrAl using the 3D full core simulator NESTLE. Evolution of the FeCrAl cladding behavior over time is evaluated by using steady-state operating conditions such as a simple axial power profile, a constant cladding surface temperature, and a constant fuel power history. The fuel rod designs and operating conditions used are based off the Peach Bottom BWR and design consideration was given to minimize the neutronic penalty of the FeCrAl cladding by changing fuel enrichment and cladding thickness. As this study progressed, systematic parametric analysis of the fuel and cladding creep responses were also performed.« less

Towards a Social Networks Model for Online Learning & Performance

ERIC Educational Resources Information Center

Chung, Kon Shing Kenneth; Paredes, Walter Christian

2015-01-01

In this study, we develop a theoretical model to investigate the association between social network properties, "content richness" (CR) in academic learning discourse, and performance. CR is the extent to which one contributes content that is meaningful, insightful and constructive to aid learning and by social network properties we…

Incineration of tannery sludge under oxic and anoxic conditions: study of chromium speciation.

PubMed

Kavouras, P; Pantazopoulou, E; Varitis, S; Vourlias, G; Chrissafis, K; Dimitrakopulos, G P; Mitrakas, M; Zouboulis, A I; Karakostas, Th; Xenidis, A

2015-01-01

A tannery sludge, produced from physico-chemical treatment of tannery wastewaters, was incinerated without any pre-treatment process under oxic and anoxic conditions, by controlling the abundance of oxygen. Incineration in oxic conditions was performed at the temperature range from 300°C to 1200°C for duration of 2h, while in anoxic conditions at the temperature range from 400°C to 600°C and varying durations. Incineration under oxic conditions at 500°C resulted in almost total oxidation of Cr(III) to Cr(VI), with CaCrO4 to be the crystalline phase containing Cr(VI). At higher temperatures a part of Cr(VI) was reduced, mainly due to the formation of MgCr2O4. At 1200°C approximately 30% of Cr(VI) was reduced to Cr(III). Incineration under anoxic conditions substantially reduced the extent of oxidation of Cr(III) to Cr(VI). Increase of temperature and duration of incineration lead to increase of Cr(VI) content, while no chromium containing crystalline phase was detected. Copyright © 2014 Elsevier B.V. All rights reserved.

Testing Cadmium-Free Coatings

DTIC Science & Technology

2011-08-30

Chromium (Cr6+) None Zinc Cr6+ None Zinc Trivalent Chromium Process (TCP) Enseal C22 Zinc Nickel TCP Enseal C22 High Purity Al TCP Enseal C22 Zn-rich two...Secretary of Defense Directive • “Approve the use of alternatives [to hexavalent chromium (Cr6+)] where they can perform adequately for the intended

78 FR 21912 - Proposed Information Collection; Comment Request; Crab Rationalization (CR) Program: Annual Report

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-12

... performance of the CR Program during its first 5 years. Based on the report and public testimony, the Council... paper concerning certain measures from CR cooperatives that might promote acquisition of QS by crew and... that the paper examine the ``best practice'' requirements for cooperative agreements. The paper was...

Computationally Efficient Power Allocation Algorithm in Multicarrier-Based Cognitive Radio Networks: OFDM and FBMC Systems

NASA Astrophysics Data System (ADS)

Shaat, Musbah; Bader, Faouzi

2010-12-01

Cognitive Radio (CR) systems have been proposed to increase the spectrum utilization by opportunistically access the unused spectrum. Multicarrier communication systems are promising candidates for CR systems. Due to its high spectral efficiency, filter bank multicarrier (FBMC) can be considered as an alternative to conventional orthogonal frequency division multiplexing (OFDM) for transmission over the CR networks. This paper addresses the problem of resource allocation in multicarrier-based CR networks. The objective is to maximize the downlink capacity of the network under both total power and interference introduced to the primary users (PUs) constraints. The optimal solution has high computational complexity which makes it unsuitable for practical applications and hence a low complexity suboptimal solution is proposed. The proposed algorithm utilizes the spectrum holes in PUs bands as well as active PU bands. The performance of the proposed algorithm is investigated for OFDM and FBMC based CR systems. Simulation results illustrate that the proposed resource allocation algorithm with low computational complexity achieves near optimal performance and proves the efficiency of using FBMC in CR context.

One Dimensional Cold Rolling Effects on Stress Corrosion Crack Growth in Alloy 690 Tubing and Plate Materials

NASA Astrophysics Data System (ADS)

Toloczko, Mychailo B.; Olszta, Matthew J.; Bruemmer, Stephen M.

Stress corrosion crack-growth experiments have been performed on cold-rolled alloy 690 materials in simulated PWR primary water at 360°C. Extruded alloy 690 CRDM tubing in two conditions, thermally treated (TT) and solution annealed (SA), was cold rolled (CR) in one direction to several reductions reaching a maximum of 31% and tested in the S-L orientation. High stress corrosion cracking (SCC) propagation rates ( 8x10-8 mm/s) were observed for the 31%CR alloy 690TT material, while the 31%CR alloy 690SA exhibited 10X lower rates. The difference in intergranular SCC susceptibility appears to be related to grain boundary carbide distribution before cold rolling. SCC growth rates were found to depend on test temperature and hydrogen concentration. Tests were also performed on two alloy 690 plate heats, one CR to a reduction of 26% and the other to 20%. SCC growth rates at 360°C were similar to that measured for the 31%CR alloy 690TT CRDM tubing. Comparisons will be made to other results on CR alloy 690 materials.

Performance of iron-chromium-aluminum alloy surface coatings on Zircaloy 2 under high-temperature steam and normal BWR operating conditions

NASA Astrophysics Data System (ADS)

Zhong, Weicheng; Mouche, Peter A.; Han, Xiaochun; Heuser, Brent J.; Mandapaka, Kiran K.; Was, Gary S.

2016-03-01

Iron-chromium-aluminum (FeCrAl) coatings deposited on Zircaloy 2 (Zy2) and yttria-stabilized zirconia (YSZ) by magnetron sputtering have been tested with respect to oxidation weight gain in high-temperature steam. In addition, autoclave testing of FeCrAl-coated Zy2 coupons under pressure-temperature-dissolved oxygen coolant conditions representative of a boiling water reactor (BWR) environment has been performed. Four different FeCrAl compositions have been tested in 700 °C steam; compositions that promote alumina formation inhibited oxidation of the underlying Zy2. Parabolic growth kinetics of alumina on FeCrAl-coated Zy2 is quantified via elemental depth profiling. Autoclave testing under normal BWR operating conditions (288 °C, 9.5 MPa with normal water chemistry) up to 20 days demonstrates observable weight gain over uncoated Zy2 simultaneously exposed to the same environment. However, no FeCrAl film degradation was observed. The 900 °C eutectic in binary Fe-Zr is addressed with the FeCrAl-YSZ system.

Dependence with the oxidation state of X-ray transition energies, intensities and natural line widths of CrKβ spectra

NASA Astrophysics Data System (ADS)

Torres Deluigi, M.; Tirao, G.; Stutz, G.; Cusatis, C.; Riveros, J. A.

2006-06-01

The Kβ emission spectrum of chromium was experimentally analyzed in different compounds and compared with previous data. Measurements of whole Kβ spectra were performed with a wavelength dispersive commercial XRF equipment. To study possible effects of the chemical state in the width and position of the main Kβ 1,3 line, high resolution measurements were also performed. In the latter measurements, a spectrometer based on a backdiffracting crystal analyzer with spherical focalization and synchrotron radiation monochromatic excitation was used. Kβ 1,3 line shifts in relation to metallic Cr were observed, both to higher energies (≅+1 eV) for Cr III and to lower energies (≅-0.5 eV) for Cr VI. It was also found that the natural width of CrKβ 1,3 line, the ionization energy of the 3p orbital of Cr, and the relative intensities of Kβ″ and Kβ 2,5 lines with respect to the main Kβ 1,3 line increase as the oxidation state increases. The use of these features as an index for chemical state analysis is discussed.

Hydrothermal Carbonization of Microalgae (Chlorococcum sp.) for Porous Carbons With High Cr(VI) Adsorption Performance.

PubMed

Sun, Yuanyuan; Liu, Chang; Zan, Yifan; Miao, Gai; Wang, Hao; Kong, Lingzhao

2018-04-12

Porous carbon adsorbents were prepared from microalgae (Chlorococcum sp.) via directly hydrothermal carbonization coupled with KOH or NH 3 activation for Cr(VI) adsorption. KOH-activated porous carbons exhibit high Cr(VI) adsorption capacities than those obtained via NH 3 modification (370.37 > 95.70 mg/g). The superior Cr(VI) adsorption capacity is due to high surface areas (1784 m 2 /g) and pore volumes of porous carbon with mesoporous and macroporous structures. The Cr(VI) adsorption result was well fitted to the Langmuir model, showing that the removal of Cr(VI) was attributed to the monolayer adsorption of activity site on carbon surface.

Radiation Tolerance of Controlled Fusion Welds in High Temperature Oxidation Resistant FeCrAl Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gussev, Maxim N.; Field, Kevin G.

High temperature oxidation resistant iron-chromium-aluminum (FeCrAl) alloys are candidate alloys for nuclear applications due to their exceptional performance during off-normal conditions such as a loss-of-coolant accident (LOCA) compared to currently deployed zirconium-based claddings [1]. A series of studies have been completed to determine the weldability of the FeCrAl alloy class and investigate the weldment performance in the as-received (non-irradiated) state [2,3]. These initial studies have shown the general effects of composition and microstructure on the weldability of FeCrAl alloys. Given this, limited details on the radiation tolerance of FeCrAl alloys and their weldments exist. Here, the highest priority candidate FeCrAlmore » alloys and their weldments have been investigated after irradiation to enable a better understanding of FeCrAl alloy weldment performance within a high-intensity neutron field. The alloys examined include C35M (Fe-13%Cr-5% Al) and variants with aluminum (+2%) or titanium carbide (+1%) additions. Two different sub-sized tensile geometries, SS-J type and SS-2E (or SS-mini), were neutron irradiated in the High Flux Isotope Reactor to 1.8-1.9 displacements per atom (dpa) in the temperature range of 195°C to 559°C. Post irradiation examination of the candidate alloys was completed and included uniaxial tensile tests coupled with digital image correlation (DIC), scanning electron microscopy-electron back scattered diffraction analysis (SEM-EBSD), and SEM-based fractography. In addition to weldment testing, non-welded parent material was examined as a direct comparison between welded and non-welded specimen performance. Both welded and non-welded specimens showed a high degree of radiation-induced hardening near irradiation temperatures of 200°C, moderate radiation-induced hardening near temperatures of 360°C, and almost no radiation-induced hardening at elevated temperatures near 550°C. Additionally, low-temperature irradiations showed the non-welded specimens to exhibit strain-induced softening (decrease in the true stress level) with increasing plastic strain during tensile testing. Fracture for the weldments was found to occur exclusively within the fusion zone. The mechanical performance of the weldment was speculated to be directly linked to variances in the radiation-induced microstructure including the formation of dislocation loops and precipitation of the Cr-rich α' phase. The localized microstructural variation within the weldments, including grain size, was determined to play a significant role in the radiation-induced microstructure. The results summarized within highlight the need for additional data on the radiation tolerance of weldments as the mechanical performance of the fusion zone was shown to be the limiting factor in the overall performance of the weldments.« less

Effects of 4 weeks of creatine supplementation in junior swimmers on freestyle sprint and swim bench performance.

PubMed

Dawson, Brian; Vladich, Todd; Blanksby, Brian A

2002-11-01

To determine whether 4 weeks of oral creatine (Cr) supplementation could enhance single freestyle sprint and swim bench performance in experienced competitive junior swimmers, 10 young men and 10 young women (x age = 16.4 +/- 1.8 years) participated in a 27-day supplementation period and pre- and posttesting sessions. In session 1 (presupplementation testing), subjects swam one 50-m freestyle and then (after approximately 5 minutes of active recovery) one 100-m freestyle at maximum speed. Blood lactate was measured before and 1 minute after each swim trial. Forty-eight hours later, height, mass, and the sum of 6 skinfolds were recorded, and a Biokinetic Swim Bench total work output test (2 x 30-second trials, with a 10-minute passive recovery in between) was undertaken. After the pretests were completed, participants were divided into 2 groups (n = 10, Cr; and n = 10, placebo) by means of matched pairs on the basis of gender and 50-m swim times. A Cr loading phase of 20 g x d(-1) for 5 days was then instituted, followed by a maintenance phase of 5 g x d(-1) for 22 days. Postsupplementation testing replicated the presupplementation tests. Four weeks of Cr supplementation did not influence single sprint performance in the pool or body mass and composition. However, 30-second swim bench total work scores for trial 1 and trial 2 increased after Cr (p < 0.05) but not placebo ingestion. Postexercise blood lactate values were not different after supplementation for the 50- and 100-m sprint trials either within or between groups. It was concluded that 4 weeks of Cr supplementation did not significantly improve single sprint performance in competitive junior swimmers, but it did enhance swim bench test performance.

Magnetic properties of TM3[Cr(CN)6]2.n H2O

NASA Astrophysics Data System (ADS)

Zentková, M.; Mihalik, M.; Ková, J.; Zentko, A.; Mitróová, Z.; Lukáová, M.; Kaveanský, V.; Kiss, L. F.

2006-01-01

Magnetization measurements performed on Prussian blue analogs TM2+3[CrIII(CN)6]2.n H2O (TM = Cr, Mn, Fe, Co, Ni, Cu) confirmed the dual character of the exchange interaction (antiferromagnetic AFM and ferromagnetic FM) in this system. AFM interaction dominates for the Cr2+ sample and with rising atomic number Z the FM interaction becomes more important reaching pure FM character for the Cu2+ sample.

Speciation of chromium in environmental samples by dual electromembrane extraction system followed by high performance liquid chromatography.

PubMed

Safari, Meysam; Nojavan, Saeed; Davarani, Saied Saeed Hosseiny; Morteza-Najarian, Amin

2013-07-30

This study proposes the dual electromembrane extraction followed by high performance liquid chromatography for selective separation-preconcentration of Cr(VI) and Cr(III) in different environmental samples. The method was based on the electrokinetic migration of chromium species toward the electrodes with opposite charge into the two different hollow fibers. The extractant was then complexed with ammonium pyrrolidinedithiocarbamate for HPLC analysis. The effects of analytical parameters including pH, type of organic solvent, sample volume, stirring rate, time of extraction and applied voltage were investigated. The results showed that Cr(III) and Cr(VI) could be simultaneously extracted into the two different hollow fibers. Under optimized conditions, the analytes were quantified by HPLC instrument, with acceptable linearity ranging from 20 to 500 μg L(-1) (R(2) values≥0.9979), and repeatability (RSD) ranging between 9.8% and 13.7% (n=5). Also, preconcentration factors of 21.8-33 that corresponded to recoveries ranging from 31.1% to 47.2% were achieved for Cr(III) and Cr(VI), respectively. The estimated detection limits (S/N ratio of 3:1) were less than 5.4 μg L(-1). Finally, the proposed method was successfully applied to determine Cr(III) and Cr(VI) species in some real water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Hydrogen attack in Cr-Mo steels. [3Cr-1. 5Mo and 2. 25Cr-1Mo steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruoff, S.; Stone, D.; Wanagel, J.

Experiments conducted upon 3Cr-1.5Mo steel at elevated temperatures (600 C), and high pressure hydrogen (2000 psi), have shown a greater resistence to hydrogen attack compared with similar studies of 2.25Cr-lMo steels. Hydrogen exposure tests with and without an applied stress have been performed on both types of steels. Results of similar conditions show clear evidence of hydrogen attack in 2.25Cr-lMo steel, however, for the 3Cr-1.5Mo steel with exposure time up to 80 days without an applied stress no evidence of hydrogen attack is observed. For stress-rupture tests using stresses of 14 and 16 ksi, the 3Cr-1.5Mo steel showed no effectsmore » of hydrogen attack, and no damage was observed using a SEM.« less

Cognitive Reserve in Dementia: Implications for Cognitive Training

PubMed Central

Mondini, Sara; Madella, Ileana; Zangrossi, Andrea; Bigolin, Angela; Tomasi, Claudia; Michieletto, Marta; Villani, Daniele; Di Giovanni, Giuseppina; Mapelli, Daniela

2016-01-01

Cognitive reserve (CR) is a potential mechanism to cope with brain damage. The aim of this study was to evaluate the effect of CR on a cognitive training (CT) in a group of patients with dementia. Eighty six participants with mild to moderate dementia were identified by their level of CR quantified by the CR Index questionnaire (CRIq) and underwent a cycle of CT. A global measure of cognition mini mental state examination (MMSE) was obtained before (T0) and after (T1) the training. Multiple linear regression analyses highlighted CR as a significant factor able to predict changes in cognitive performance after the CT. In particular, patients with lower CR benefited from a CT program more than those with high CR. These data show that CR can modulate the outcome of a CT program and that it should be considered as a predictive factor of neuropsychological rehabilitation training efficacy in people with dementia. PMID:27199734

The irradiation hardening of Ni-Mo-Cr and Ni-W-Cr alloy under Xe26+ ion irradiation

NASA Astrophysics Data System (ADS)

Chen, Huaican; Hai, Yang; Liu, Renduo; Jiang, Li; Ye, Xiang-xi; Li, Jianjian; Xue, Wandong; Wang, Wanxia; Tang, Ming; Yan, Long; Yin, Wen; Zhou, Xingtai

2018-04-01

The irradiation hardening of Ni-Mo-Cr and Ni-W-Cr alloy was investigated. 7 MeV Xe26+ ion irradiation was performed at room temperature and 650 °C with peak damage dose from 0.05 to 10 dpa. With the increase of damage dose, the hardness of Ni-Mo-Cr and Ni-W-Cr alloy increases, and reaches saturation at damage dose ≥1 dpa. Moreover, the damage dose dependence of hardness in both alloys can be described by the Makin and Minter's equation, where the effective critical volume of obstacles can be used to represent irradiation hardening resistance of the alloys. Our results also show that Ni-W-Cr alloy has better irradiation hardening resistance than Ni-Mo-Cr alloy. This is ascribed to the fact that the W, instead of Mo in the alloy, can suppress the formation of defects under ion irradiation.

Dynamics of a Cr spin in a semiconductor quantum dot: Hole-Cr flip-flops and spin-phonon coupling

NASA Astrophysics Data System (ADS)

Lafuente-Sampietro, A.; Utsumi, H.; Sunaga, M.; Makita, K.; Boukari, H.; Kuroda, S.; Besombes, L.

2018-04-01

A detailed analysis of the photoluminescence (PL) intensity distribution in singly Cr-doped CdTe/ZnTe quantum dots (QDs) is performed. First of all, we demonstrate that hole-Cr flip-flops induced by an interplay of the hole-Cr exchange interaction and the coupling with acoustic phonons are the main source of spin relaxation within the exciton-Cr complex. This spin flip mechanism appears in the excitation power dependence of the PL of the exciton as well as in the intensity distribution of the resonant PL. The resonant optical pumping of the Cr spin which was recently demonstrated can also be explained by these hole-Cr flip-flops. Despite the fast exciton-Cr spin dynamics, an analysis of the PL intensity under magnetic field shows that the hole-Cr exchange interaction in CdTe/ZnTe QDs is antiferromagnetic. In addition to the Cr spin dynamics induced by the interaction with carriers' spin, we finally demonstrate using time resolved optical pumping measurements that a Cr spin interacts with nonequilibrium acoustic phonons generated during the optical excitation inside or near the QD.

Understanding the effects of Cr doping in rutile TiO2 by DFT calculations and X-ray spectroscopy.

PubMed

Vásquez, G Cristian; Maestre, David; Cremades, Ana; Ramírez-Castellanos, Julio; Magnano, Elena; Nappini, Silvia; Karazhanov, Smagul Zh

2018-06-07

The effects of Cr on local environment and electronic structure of rutile TiO 2 are studied combining theoretical and experimental approaches. Neutral and negatively charged substitutional Cr impurities Cr Ti 0 and Cr Ti 1- as well as Cr-oxygen vacancy complex 2Cr Ti  + V O are studied by the density functional theory (DFT) within the generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) functional. Experimental results based on X-Ray absorption spectroscopy (XAS) and X-Ray photoelectron spectroscopy (XPS) performed on Cr doped TiO 2 at the Synchrotron facility were compared to the theoretical results. It is shown that the electrons of the oxygen vacancy tend to be localized at the t 2g states of the Cr ions in order to reach the stable oxidation state of Cr 3+ . Effects of Cr on crystal field (CF) and structural distortions in the rutile TiO 2 cell were analyzed by the DFT calculations and XAS spectra revealing that the CF and tetragonal distortions in TiO 2 are very sensitive to the concentration of Cr.

Site-specific functionalization for chemical speciation of Cr(III) and Cr(VI) using polyaniline impregnated nanocellulose composite: equilibrium, kinetic, and thermodynamic modeling

NASA Astrophysics Data System (ADS)

Jain, Priyanka; Varshney, Shilpa; Srivastava, Shalini

2017-07-01

Site-specific functionalizations are the emergent attention for the enhancement of sorption latent of heavy metals. Limited chemistry has been applied for the fabrication of diafunctionalized materials having potential to tether both environmentally stable oxidation states of chromium (Cr(III) and Cr(VI). Polyaniline impregnated nanocellulose composite (PANI-NCC) has been fabricated using click chemistry and explored for the removal of Cr(III) and Cr(VI) from hydrological environment. The structure, stability, morphology, particle size, surface area, hydrophilicity, and porosity of fabricated PANI-NCC were characterized comprehensively using analytical techniques and mathematical tools. The maximum sorption performance of PANI-NCC was procured for (Cr(III): 47.06 mg g-1; 94.12 %) and (Cr(VI): 48.92 mg g-1; 97.84 %) by equilibrating 0.5 g sorbent dose with 1000 mL of 25 mg L-1 chromium conc. at pH 6.5 and 2.5 for Cr(III) and Cr(VI), respectively. The sorption data showed a best fit to the Langmuir isotherm and pseudo-second-order kinetic model. The negative value of Δ G° (-8.59 and -11.16 kJ mol-1) and Δ H° (66.46 × 10-1 and 17.84 × 10-1 kJ mol-1), and positive value of Δ S° (26.66 and 31.46 J mol-1K-1) for Cr(III) and Cr(VI), respectively, reflect the spontaneous, feasibility, and exothermic nature of the sorption process. The application of fabricated PANI-NCC for removing both the forms of chromium in the presence of other heavy metals was also tested at laboratory and industrial waste water regime. These findings open up new avenues in the row of high performance, scalable, and economic nanobiomaterial for the remediation of both forms of chromium from water streams.

Effect of alkaline precipitation on Cr species of Cr(III)-bearing complexes typically used in the tannery industry.

PubMed

Wang, Dandan; Ye, Yuxuan; Liu, Hui; Ma, Hongrui; Zhang, Weiming

2018-02-01

Various organic compounds extensively used in the leather industry could influence the performance of alkaline precipitation with Cr(III). This study focused on two typical Cr(III)-bearing complexes (Cr(III)-collagen and Cr(III)-citrate) ubiquitous in tannery effluent yet with distinct treatment efficiencies, as Cr(III) was much more difficult to remove in the Cr(III)-citrate solution. Comprehensive analytical methods were employed to explore the intrinsic mechanism. It was found that a lower removal efficiency towards Cr(III) was significantly associated with higher oligomers. The molecular size of the Cr(III)-citrate complex continued to increase with rising pH, making it larger overall than Cr(III)-collagen species. The growing oligomer moiety of dissolved Cr(III)-complex species could persist in the stronger basic pH range, leading to the large amount of residual Cr(III) in the Cr(III)-citrate system. Combining this result with potentiometric titration and X-ray photoelectron spectroscopy data, it was believed that the polymeric species other than monomers facilitated resisting the attack from hydroxide ions, and the postulated Cr(III)-citrate species towards higher oligomers were discovered. Beyond that, both charge neutralization and sweeping effects were presented among the gradually emerging flocs in the Cr(III)-collagen system together with the electric double layer compression effect derived from salinity, thus resulting in a larger floc size and higher Cr(III) removal efficiency in saline solutions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Removal of Cr(VI) by nanoscale zero-valent iron (nZVI) from soil contaminated with tannery wastes.

PubMed

Singh, Ritu; Misra, Virendra; Singh, Rana Pratap

2012-02-01

The illegal disposal of tannery wastes at Rania, Kanpur has resulted in accumulation of hexavalent chromium [Cr(VI)], a toxic heavy metal in soil posing risk to human health and environment. 27 soil samples were collected at various depths from Rania for the assessment of Cr(VI) level in soil. Out of 27 samples, five samples had shown significant level of Cr(VI) with an average concentration of 15.84 mg Kg(-1). Varied doses of nanoscale zero-valent iron (nZVI) were applied on Cr(VI) containing soil samples for remediation of Cr(VI). Results showed that 0.10 g L(-1) nZVI completely reduces Cr(VI) within 120 min following pseudo first order kinetics. Further, to test the efficacy of nZVI in field, soil windrow experiments were performed at the contaminated site. nZVI showed significant Cr(VI) reduction at field also, indicating it an effective tool for managing sites contaminated with Cr(VI).

Analyzing Discrepancies in a Software Development Project Change Request (CR) Assessment Process and Recommendations for Process Improvements

NASA Technical Reports Server (NTRS)

Cunningham, Kenneth James

2003-01-01

The Change Request (CR) assessment process is essential in the display development cycle. The assessment process is performed to ensure that the changes stated in the description of the CR match the changes in the actual display requirements. If a discrepancy is found between the CR and the requirements, the CR must be returned to the originator for corrections. Data was gathered from each of the developers to determine the type of discrepancies and the amount of time spent assessing each CR. This study sought to determine the most common types of discrepancies, and the amount of time required to assessing those issues. The study found that even though removing discrepancy before an assessment would save half the time needed to assess an CR with a discrepancy, the number of CR's found to have a discrepancy was very small compared to the total number of CR's assessed during the data gathering period.

Role of Oxides and Porosity on High-Temperature Oxidation of Liquid-Fueled HVOF Thermal-Sprayed Ni50Cr Coatings

NASA Astrophysics Data System (ADS)

Song, B.; Bai, M.; Voisey, K. T.; Hussain, T.

2017-02-01

High chromium content in Ni50Cr thermally sprayed coatings can generate a dense and protective scale at the surface of coating. Thus, the Ni50Cr coating is widely used in high-temperature oxidation and corrosion applications. A commercially available gas atomized Ni50Cr powder was sprayed onto a power plant steel (ASME P92) using a liquid-fueled high velocity oxy-fuel thermal spray with three processing parameters in this study. Microstructure of as-sprayed coatings was examined using oxygen content analysis, mercury intrusion porosimetry, scanning electron microscope (SEM), energy-dispersive x-ray spectroscopy (EDX) and x-ray diffraction (XRD). Short-term air oxidation tests (4 h) of freestanding coatings (without boiler steel substrate) in a thermogravimetric analyzer at 700 °C were performed to obtain the kinetics of oxidation of the as-sprayed coating. Long-term air oxidation tests (100 h) of the coated substrates were performed at same temperature to obtain the oxidation products for further characterization in detail using SEM/EDX and XRD. In all samples, oxides of various morphologies developed on top of the Ni50Cr coatings. Cr2O3 was the main oxidation product on the surface of all three coatings. The coating with medium porosity and medium oxygen content has the best high-temperature oxidation performance in this study.

The effect of annealing on structure and hardness of (Fe-Cr)-50 at.% Al coatings synthesized by mechanical alloying

NASA Astrophysics Data System (ADS)

Ciswandi, Aryanto, Didik; Irmaniar, Tjahjono, Arif; Sudiro, Toto

2018-05-01

In this research, the deposition of (Fe-Cr)-50at.% Al coatings on low carbon steel was carried out by a mechanical alloying (MA) technique. The MA was performed in a shaker mill for 4 hours. Two types of Fe-Cr powders as starting material were used, high purity Fe-Cr powders: (Fe-12.5Cr)-50Al and (Fe-25Cr)-50Al, and Fe-Cr lump powder: (50FeCr)-50Al (in at.%). The coated samples were then annealed in a vacuum furnace at 700°C for 1h. The characterizations of coating structure before and after annealing were studied by XRD and SEM-EDX, while the coating hardness was measured by micro-Vickers hardness tester. Before annealing, all of coating composition were composed mainly of (Fe,Cr)Al phase. After annealing, the FeAl and Fe0.99Cr0.02Al0.99 intermetallic phases was formed in the (Fe-12.5Cr)-50Al and (Fe-25Cr)-50Al coatings. In addition, Fe2CrAlwas also found in the (Fe-25Cr)-50Al coating. Whilethe AlCr2 intermetallic phase was detected as the main phase of (50FeCr)-50Al coating. The cross-sectional microstructure showed that the (Fe-12.5Cr)-50Al and (Fe-25Cr)-50Al coatings have a smoother structure compared to (50FeCr)-50Al coating. The annealing led to intermetallic phase formation and an increasing coating hardness.

XAS study of chromium in Li 2MSiO 4 (M=Mg, Zn)

NASA Astrophysics Data System (ADS)

Jousseaume, C.; Ribot, F.; Kahn-Harari, A.; Vivien, D.; Villain, F.

2003-01-01

X-ray absorption spectroscopy (XAS) investigations at the Cr K-edge on Cr:Li 2MSiO 4 (M=Mg, Zn) have been performed to understand the exceptionally long fluorescence lifetime of Cr IV. Previous work has shown the simultaneous presence of three oxidation states Cr IV, Cr V and Cr VI. X-ray absorption near edge structure measurements confirm that Cr in Li 2MSiO 4 (M=Mg, Zn) single crystals is in tetrahedral coordination. They also reveal that Cr VI is the dominant species in Li 2MgSiO 4, and that Li 2ZnSiO 4 contains more Cr V than Li 2MgSiO 4. The extended X-ray absorption fine structure spectra of Cr:Li 2MgSiO 4 single crystals recorded at the Cr K-edge, are fitted with two types of Cr environments: the first one corresponds to oxygen atoms at a mean distance of 1.68 Å and the second to oxygen atoms at a mean distance of 2.07 Å. This second environment is attributed to Cr III in the minor parasitic phase LiCr IIIO 2. The first environment corresponds to Cr that substitutes silicon in the Li 2MgSiO 4 lattice in the silicon site if the cations sizes are considered.

Fuel Performance Calculations for FeCrAl Cladding in BWRs

DOE Office of Scientific and Technical Information (OSTI.GOV)

George, Nathan; Sweet, Ryan; Maldonado, G. Ivan

2015-01-01

This study expands upon previous neutronics analyses of the reactivity impact of alternate cladding concepts in boiling water reactor (BWR) cores and directs focus toward contrasting fuel performance characteristics of FeCrAl cladding against those of traditional Zircaloy. Using neutronics results from a modern version of the 3D nodal simulator NESTLE, linear power histories were generated and supplied to the BISON-CASL code for fuel performance evaluations. BISON-CASL (formerly Peregrine) expands on material libraries implemented in the BISON fuel performance code and the MOOSE framework by providing proprietary material data. By creating material libraries for Zircaloy and FeCrAl cladding, the thermomechanical behaviormore » of the fuel rod (e.g., strains, centerline fuel temperature, and time to gap closure) were investigated and contrasted.« less

Natriuretic Peptide and Clinical Evaluation in the Diagnosis of Heart Failure Hemodynamic Profile: Comparison with Tissue Doppler Echocardiography.

PubMed

Almeida Junior, Gustavo Luiz Gouvêa de; Clausell, Nadine; Garcia, Marcelo Iorio; Esporcatte, Roberto; Rangel, Fernando Oswaldo Dias; Rocha, Ricardo Mourilhe; Beck-da-Silva, Luis; Silva, Fabricio Braga da; Gorgulho, Paula de Castro Carvalho; Xavier, Sergio Salles

2018-03-01

Physical examination and B-type natriuretic peptide (BNP) have been used to estimate hemodynamics and tailor therapy of acute decompensated heart failure (ADHF) patients. However, correlation between these parameters and left ventricular filling pressures is controversial. This study was designed to evaluate the diagnostic accuracy of physical examination, chest radiography (CR) and BNP in estimating left atrial pressure (LAP) as assessed by tissue Doppler echocardiogram. Patients admitted with ADHF were prospectively assessed. Diagnostic characteristics of physical signs of heart failure, CR and BNP in predicting elevation (> 15 mm Hg) of LAP, alone or combined, were calculated. Spearman test was used to analyze the correlation between non-normal distribution variables. The level of significance was 5%. Forty-three patients were included, with mean age of 69.9 ± 11.1years, left ventricular ejection fraction of 25 ± 8.0%, and BNP of 1057 ± 1024.21 pg/mL. Individually, all clinical, CR or BNP parameters had a poor performance in predicting LAP ≥ 15 mm Hg. A clinical score of congestion had the poorest performance [area under the receiver operating characteristic curve (AUC) 0.53], followed by clinical score + CR (AUC 0.60), clinical score + CR + BNP > 400 pg/mL (AUC 0.62), and clinical score + CR + BNP > 1000 pg/mL (AUC 0.66). Physical examination, CR and BNP had a poor performance in predicting a LAP ≥ 15 mm Hg. Using these parameters alone or in combination may lead to inaccurate estimation of hemodynamics.

Development of Process Analytical Technology (PAT) methods for controlled release pellet coating.

PubMed

Avalle, P; Pollitt, M J; Bradley, K; Cooper, B; Pearce, G; Djemai, A; Fitzpatrick, S

2014-07-01

This work focused on the control of the manufacturing process for a controlled release (CR) pellet product, within a Quality by Design (QbD) framework. The manufacturing process was Wurster coating: firstly layering active pharmaceutical ingredient (API) onto sugar pellet cores and secondly a controlled release (CR) coating. For each of these two steps, development of a Process Analytical Technology (PAT) method is discussed and also a novel application of automated microscopy as the reference method. Ultimately, PAT methods should link to product performance and the two key Critical Quality Attributes (CQAs) for this CR product are assay and release rate, linked to the API and CR coating steps respectively. In this work, the link between near infra-red (NIR) spectra and those attributes was explored by chemometrics over the course of the coating process in a pilot scale industrial environment. Correlations were built between the NIR spectra and coating weight (for API amount), CR coating thickness and dissolution performance. These correlations allow the coating process to be monitored at-line and so better control of the product performance in line with QbD requirements. Copyright © 2014 Elsevier B.V. All rights reserved.

Evaluation of Hard Coating Performance in Drilling Compacted Graphite Iron (CGI)

NASA Astrophysics Data System (ADS)

de Paiva, José M. F.; Amorim, Fred L.; Soares, P.; Torres, Ricardo D.

2013-10-01

The aim of this investigation was to compare the performance of the following commercial coatings system, TiAlN/TiN, AlCrN, and TiSiN/AlCrN, deposited in cemented carbide tools in drilling compact graphite iron (CGI). The drilling tests were conducted adopting two cutting speeds: 80 or 150 m/min. For each test condition, the tool flank wear, the machining feed force, and the circularity and the roughness of the resulting drilled hole were determined. At the cutting speed of 80 m/min, the results revealed that the tool life, in terms of flank wear, was improved for the Cr-based coatings, while the multilayered coatings presented a better performance at the cutting speed of 150 m/min. It was also found that feed force is substantially increased when drilling at a cutting speed of 150 m/min. The holes drilled with the TiSiN/AlCrN at a cutting speed of 150 m/min showed the best circularity. The drill roughness is directly influenced by the coating system wear and iron adhesion. Consequently, it was found that the lowest holes' roughness was obtained with TiSiN/AlCrN at 80 m/min.

Pharmacological profile of the aerial parts of Rubus ulmifolius Schott.

PubMed

Ali, Niaz; Shaoib, Mohammad; Shah, Syed Wadood Ali; Shah, Ismail; Shuaib, Muhammad

2017-01-19

As aerial parts of Rubus ulmifolius contains phytochemicals like flavonoids and tannins. And whereas flavonoids and tannins have antioxidant and antipyretic activity, hence, current work is carried out to screen crude methanolic extract of aerial parts of Rubus ulmifolius (Ru.Cr) and crude flavonoids rich extract of Rubus ulmifolius (Ru.F) for possible antioxidant and antipyretic activity. Ru.Cr and Ru.F are also tested for brine shrimps lethality bioassay. Ru.F is tested for the first time for possible antioxidant and antipyretic activity. Preliminary phytochemical screening of Ru.Cr and Ru.F was performed as it provides rapid finger printing for targeting a pharmacological activity. Acute toxicity and Brine shrimps' cytotoxicity studies of Ru.Cr and Ru.F were performed to determine its safe dose range. Antioxidant and antipyretic studies were also performed as per reported procedures. Ru.Cr tested positive for presence of tannins, alkaloids, flavonoids and steroids. Ru.Cr is safe up to 6 g/kg following oral doses for acute toxicity study. Ru.Cr is safe up to 75 μg/kg (p.o), LC 50 for Ru.Cr and Ru.F are 16.7 ± 1.4 μg/ml 10.6 ± 1.8 μg/ml, respectively (n = 3). Both Ru.Cr and Ru.F demonstrated comparable antioxidant activity using vitamin C as standard (p ≤ 0.05). In test dose of 300 mg of Ru.Cr, rectal temperature was reduced by 74% (p ≤ 0.05) on 4 th hour of the administration. More, Ru.F produced 72% reduction in pyrexia (p ≤ 0.05) on 4 th hour of administration of paracetamol in Westar rats. The current work confirms that aerial parts of Rubus ulmifolius contain flavonoids that are safe up to 6 g/kg (p.o). Crude methanolic extract and flavonoids rich fraction of Rubus ulmifolius have significant antioxidant and antipyretic activity. Further work is required to isolate the pharmacologically active substances for relatively safe and effective antipyretics and antioxidants.

Cold ischemia contributes to the development of chronic rejection and mitochondrial injury after cardiac transplantation.

PubMed

Schneeberger, Stefan; Amberger, Albert; Mandl, Julia; Hautz, Theresa; Renz, Oliver; Obrist, Peter; Meusburger, Hugo; Brandacher, Gerald; Mark, Walter; Strobl, Daniela; Troppmair, Jakob; Pratschke, Johann; Margreiter, Raimund; Kuznetsov, Andrey V

2010-12-01

Chronic rejection (CR) remains an unsolved hurdle for long-term heart transplant survival. The effect of cold ischemia (CI) on progression of CR and the mechanisms resulting in functional deficit were investigated by studying gene expression, mitochondrial function, and enzymatic activity. Allogeneic (Lew→F344) and syngeneic (Lew→Lew) heart transplantations were performed with or without 10 h of CI. After evaluation of myocardial contraction, hearts were excised at 2, 10, 40, and 60 days for investigation of vasculopathy, gene expression, enzymatic activities, and mitochondrial respiration. Gene expression studies identified a gene cluster coding for subunits of the mitochondrial electron transport chain regulated in response to CI and CR. Myocardial performance, mitochondrial function, and mitochondrial marker enzyme activities declined in all allografts with time after transplantation. These declines were more rapid and severe in CI allografts (CR-CI) and correlated well with progression of vasculopathy and fibrosis. Mitochondria related gene expression and mitochondrial function are substantially compromised with the progression of CR and show that CI impacts on progression, gene profile, and mitochondrial function of CR. Monitoring mitochondrial function and enzyme activity might allow for earlier detection of CR and cardiac allograft dysfunction. © 2010 The Authors. Journal compilation © 2010 European Society for Organ Transplantation.

Control of substrate oxidation in MOD cerawwwmic coating on low-activation ferritic steel with reduced-pressure atmosphere

NASA Astrophysics Data System (ADS)

Tanaka, Teruya; Muroga, Takeo

2014-12-01

An Er2O3 ceramic coating fabricated using the metal-organic decomposition (MOD) method on a Cr2O3-covered low-activation ferritic steel JLF-1 substrate was examined to improve hydrogen permeation barrier performance of the coating. The Cr2O3 layer was obtained before coating by heat treating the substrate at 700 °C under reduced pressures of <5 × 10-3 Pa and 5 Pa. The Cr2O3 layer was significantly stable even with heat treatment at 700 °C in air. This layer prevented further production of Fe2O3, which has been considered to degrade coating performance. An MOD Er2O3 coating with a smooth surface was successfully obtained on a Cr2O3-covered JLF-1 substrate by dip coating followed by drying and baking. Preprocessing to obtain a Cr2O3 layer would provide flexibility in the coating process for blanket components and ducts. Moreover, the Cr2O3 layer suppressed hydrogen permeation through the JLF-1 substrate. While further optimization of the coating fabrication process is required, it would be possible to suppress hydrogen permeation significantly by multilayers of Cr2O3 and MOD oxide ceramic.

A Meta-analytic Review of Non-specific Effects in Randomized Controlled Trials of Cognitive Remediation for Schizophrenia.

PubMed

Radhakrishnan, Rajiv; Kiluk, Brian D; Tsai, Jack

2016-03-01

Cognitive remediation (CR) has been found to improve cognitive performance among adults with schizophrenia in randomized controlled trials (RCTs). However, improvements in cognitive performance are often observed in the control groups of RCTs as well. There has been no comprehensive examination of change in control groups for CR, which may inform trial methodology and improve our understanding of measured outcomes for cognitive remediation. In this meta-analysis, we calculated pre-post change in cognitive test performance within control groups of RCTs in 32 CR trials (n = 794 participants) published between 1970 and 2011, and examined the association between pre-post change and sample size, duration of treatment, type of control group, and participants' age, intelligence, duration of illness, and psychiatric symptoms. Results showed that control groups in CR trials showed small effect size changes (Cohen's d = 0.12 ± 0.16) in cognitive test performance over the trial duration. Study characteristics associated with pre-post change included participant age and sample size. These findings suggest attention to change in control groups may help improve detection of cognitive remediation effects for schizophrenia.

Effects of in ovo feeding of creatine pyruvate on the hatchability, growth performance and energy status in embryos and broiler chickens.

PubMed

Zhao, M M; Gao, T; Zhang, L; Li, J L; Lv, P A; Yu, L L; Gao, F; Zhou, G H

2017-10-01

The effects of in ovo feeding (IOF) of creatine pyruvate (CrPyr) on the hatchability, growth performance and energy status of embryos and broilers (Arbor Acres) were investigated. Five treatments were arranged as non-injected treatment (Control), 0.6 ml physiological saline (0.75%) injected treatment (Saline), and IOF treatments injected with 0.6 ml physiological saline (0.75%) containing 3, 6 or 12 mg CrPyr (CrPyr3, CrPyr6 or CrPyr12) into the amnion per fertile egg on day 17.5 of incubation. After hatching, 80 male chicks from each treatment with similar weight close to the average BW of their pooled group were selected and randomly assigned into eight replicates of 10 chicks each. The results showed that the hatchability was not affected among groups, whereas the hatching weight of broilers in CrPyr12 was significantly higher than the control and saline groups (P0.05). Irrespective of dosage, the concentrations of creatine and phosphocreatine, and activities of creatine kinase in embryos were enhanced in CrPyr treatments at 19 E when compared with the control and saline groups (P<0.05). The activities of glucose-6-phosphatase in liver in CrPyr6 and CrPyr12 treatments were higher than the control and saline groups at 19 E (P<0.05). In conclusion, these results indicated that IOF of CrPyr, especially at the level of 12 mg/egg, could improve energy status of embryos and hatchlings, which was useful for enhancing hatching weight, BW and pectoral muscle weight until the end of the experiments at 21 days post-hatch in broilers.

Effects of dietary chromium picolinate and peppermint essential oil on growth performance and blood biochemical parameters of broiler chicks reared under heat stress conditions

NASA Astrophysics Data System (ADS)

Akbari, Mohsen; Torki, Mehran

2014-08-01

A study was conducted using 240 female day-old broiler chicks to evaluate the effects of dietary chromium picolinate (CrPic), peppermint essential oil (P.mint), or their combination on growth performance and blood biochemical parameters of female broiler chicks raised under heat stress conditions (HS, 23.9 to 38 °C cycling). Average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR) were obtained from 1 to 42 days of age. Furthermore, at the end of the experiment (day 42), birds were bled to determine some blood biochemical parameters and weighed for final body weight (BW). ADFI, ADG, and BW were not influenced significantly by dietary CrPic and P.mint ( P > 0.05). A significant interaction between dietary CrPic and P.mint on FCR ( P = 0.012) was detected. FCR significantly decreased in chicks fed the diet including both CrPic and P.mint compared with the CrPic group. Significant interaction between dietary P.mint and CrPic on serum concentrations of triglycerides, glucose, and albumin were observed ( P < 0.05), but the other measured blood biochemical parameters were not statistically affected by dietary treatments ( P > 0.05). The serum concentrations of glucose, triglycerides were decreased ( P < 0.05) in broilers fed the diet including both CrPic and P.mint. Plasma chromium (Cr) content increased significantly ( P < 0.05) in birds fed the CrPic-included diet compared with the control group ( P < 0.05). From the results of the present experiment it can be concluded that dietary supplementation with combined P.mint and CrPic could have beneficial effects on some blood biochemical parameters of female chicks reared under heat stress conditions.

Effects of dietary chromium picolinate and peppermint essential oil on growth performance and blood biochemical parameters of broiler chicks reared under heat stress conditions.

PubMed

Akbari, Mohsen; Torki, Mehran

2014-08-01

A study was conducted using 240 female day-old broiler chicks to evaluate the effects of dietary chromium picolinate (CrPic), peppermint essential oil (P.mint), or their combination on growth performance and blood biochemical parameters of female broiler chicks raised under heat stress conditions (HS, 23.9 to 38 °C cycling). Average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR) were obtained from 1 to 42 days of age. Furthermore, at the end of the experiment (day 42), birds were bled to determine some blood biochemical parameters and weighed for final body weight (BW). ADFI, ADG, and BW were not influenced significantly by dietary CrPic and P.mint (P>0.05). A significant interaction between dietary CrPic and P.mint on FCR (P=0.012) was detected. FCR significantly decreased in chicks fed the diet including both CrPic and P.mint compared with the CrPic group. Significant interaction between dietary P.mint and CrPic on serum concentrations of triglycerides, glucose, and albumin were observed (P<0.05), but the other measured blood biochemical parameters were not statistically affected by dietary treatments (P>0.05). The serum concentrations of glucose, triglycerides were decreased (P<0.05) in broilers fed the diet including both CrPic and P.mint. Plasma chromium (Cr) content increased significantly (P<0.05) in birds fed the CrPic-included diet compared with the control group (P<0.05). From the results of the present experiment it can be concluded that dietary supplementation with combined P.mint and CrPic could have beneficial effects on some blood biochemical parameters of female chicks reared under heat stress conditions.

Fretting crevice corrosion of stainless steel stem-CoCr femoral head connections: comparisons of materials, initial moisture, and offset length.

PubMed

Gilbert, Jeremy L; Mehta, Manav; Pinder, Bryan

2009-01-01

Modular tapers continue to be used in a wide variety of orthopedic implants. In this study, stainless steel (ASTM F-1568) femoral hip stems combined with Co-Cr-Mo alloy heads (SS/CoCr) were tested in an in vitro fretting corrosion test set-up to assess the propensity for mechanically assisted corrosion. Three different aspects of the modular design were evaluated in this study: (1) material combination compared to CoCr/CoCr, (2) wet versus dry assembly for SS/CoCr couples, and (3) 0- and 6-mm head offset for SS/CoCr couples. Fretting corrosion tests over a range of cyclic loads up to 3300 N were performed, and continuous cyclic loading at 3300 N for 1 M cycles were performed on each group (n = 5). Fretting micromotion was measured as a function of cyclic load on select couples to detect the nature and extent of motion present. The results showed that SS/CoCr couples were more susceptible to fretting corrosion than CoCr/CoCr couples, that dry assembly does not prevent fretting corrosion from taking place but raises the onset load, and that 6-mm offset heads had higher visual evidence of fretting damage but showed mixed statistical results in terms of onset loads and OCP shifts and currents compared to the 0-mm offset samples. Current and voltage excursions over 1 million cycles tended to diminish towards their unloaded control levels but did not fully recover until cyclic loading ceased. Micromotion measurements indicated fretting motions in the range of 10-25 microm where 0-mm heads tended to piston on the trunion, while 6 mm heads tended to rock. (c) 2008 Wiley Periodicals, Inc.

Negative-Electrode Catalysts for Fe/Cr Redox Cells

NASA Technical Reports Server (NTRS)

Gahn, R. F.; Hagedorn, N.

1987-01-01

Electrodes perform more consistently and less expensive. Surfaces catalyzed by bismuth and bismuth/lead developed for application on chromium electrode in iron/chromium redox electrochemical energy storage system. NASA Fe/Cr storage system incorporates two soluble electrodes consisting of acidified solutions of iron chloride (FeC13 and FeC12) and chromium chloride (CrC13 and CrC12) oxidized and reduced in power-conversion unit to store and produce electricity. Electrolytes circulated with pumps and stored in external tanks.

Effect of HIP temperature on microstructure and low cycle fatigue strength of CuCrZr alloy

NASA Astrophysics Data System (ADS)

Nishi, Hiroshi; Enoeda, Mikio

2011-10-01

In order to investigate the effect of the HIP cycle temperatures on the metallurgic degradation and the mechanical properties of CuCrZr alloy, assessments of the microstructure, tensile test, Charpy impact test and low cycle fatigue test are performed for various heat treated CuCrZr alloys, which were solution-annealed followed by water-quenched and aged state of CuCrZr with simulated HIP cycle at temperatures of 980 and 1045 °C. Grain growth occurred on 1045 °C HIP CuCrZr, though slightly on 980 °C HIP CuCrZr. Metallurgic degradation such as voids was not found by optical and SEM observations. There were coarse precipitates in all the CuCrZr and the precipitates did not easily dissolve at 980 °C. The low cycle fatigue strength of 1045 °C HIP CuCrZr was lower than that of other CuCrZr because of the metallurgic degradation caused by the heat cycle, while that of other CuCrZr was corresponding to the best fit curve of ITER MPH.

Crystal structure, Raman scattering and magnetic properties of CuCr2-xZrxSe4 and CuCr2-xSnxSe4 selenospinels

NASA Astrophysics Data System (ADS)

Pinto, C.; Galdámez, A.; Barahona, P.; Moris, S.; Peña, O.

2018-06-01

Selenospinels, CuCr2-xMxSe4 (M = Zr and Sn), were synthesized via conventional solid-state reactions. The crystal structure of CuCr1.5Sn0.5Se4, CuCr1.7Sn0.3Se4, CuCr1.5Zr0.5Se4, and CuCr1.8Zr0.2Se4 were determined using single-crystal X-ray diffraction. All the phases crystallized in a cubic spinel-type structure. The chemical compositions of the single-crystals were examined using energy-dispersive X-ray analysis (EDS). Powder X-ray diffraction patterns of CuCr1.3Sn0.7Se4 and CuCr1.7Sn0.3Se4 were consistent with phases belonging to the Fd 3 bar m Space group. An analysis of the vibrational properties on the single-crystals was performed using Raman scattering measurements. The magnetic properties showed a spin glass behavior with increasing Sn content and ferromagnetic order for CuCr1.7Sn0.3Se4.

Enhanced photoelectrochemical and optical performance of ZnO films tuned by Cr doping

NASA Astrophysics Data System (ADS)

Salem, M.; Akir, S.; Massoudi, I.; Litaiem, Y.; Gaidi, M.; Khirouni, K.

2017-04-01

In this paper, pure and Cr-doped nanostructured Zinc oxide thin films were synthesized by simple and low cost co-precipitation and spin-coating method with Cr concentration varying between 0.5 and 5 at.%. Crystalline structure of the prepared films was investigated by X-ray diffraction (XRD) and Raman spectroscopy techniques. XRD analysis indicated that the films were indexed as the hexagonal phase of wurtzite-type structure and demonstrated a decrease in the crystallite size with increasing Cr doping content. Cr doping revealed a significant effect on the optical measurements such as transmission and photoluminescence properties. The optical measurements indicated that Cr doping decreases the optical band gap and it has been shifted from 3.41 eV for pure ZnO film to 3.31 eV for 5 at.% Cr-doped one. The photoelectrochemical (PEC) sensing characteristics of Cr-doped ZnO layers were investigated. Amongst all photo-anodes with different Cr dopant concentration, the 2 at.% Cr incorporated ZnO films exhibited fast response and higher photoconduction sensitivity.

Enhanced Tribocorrosion Performance of Cr/GLC Multilayered Films for Marine Protective Application.

PubMed

Li, Lei; Liu, Lin-Lin; Li, Xiaowei; Guo, Peng; Ke, Peiling; Wang, Aiying

2018-04-18

The corrosion and tribology are all closely related to the interface/surface of materials, which are extremely important for the mechanical components used in harsh marine environments. In this work, we fabricated Cr/graphite-like carbon (GLC) multilayered films with different modulation periods on the 316L stainless steels by direct current magnetron sputtering. Tribocorrosion tests in artificial seawater show that the tribocorrosion resistance of the Cr/GLC films is improved as the modulation period decreases from 1000 to 333 nm and then drastically drops with further decreasing to 250 nm. By taking a top-layer thickening strategy for the Cr/GLC film with 250 nm modulation period, the tribocorrosion performance is significantly enhanced. The corresponded mechanisms are discussed in terms of the film structure and electrochemical corrosion behavior.

Regime-based evaluation of cloudiness in CMIP5 models

NASA Astrophysics Data System (ADS)

Jin, Daeho; Oreopoulos, Lazaros; Lee, Dongmin

2017-01-01

The concept of cloud regimes (CRs) is used to develop a framework for evaluating the cloudiness of 12 fifth Coupled Model Intercomparison Project (CMIP5) models. Reference CRs come from existing global International Satellite Cloud Climatology Project (ISCCP) weather states. The evaluation is made possible by the implementation in several CMIP5 models of the ISCCP simulator generating in each grid cell daily joint histograms of cloud optical thickness and cloud top pressure. Model performance is assessed with several metrics such as CR global cloud fraction (CF), CR relative frequency of occurrence (RFO), their product [long-term average total cloud amount (TCA)], cross-correlations of CR RFO maps, and a metric of resemblance between model and ISCCP CRs. In terms of CR global RFO, arguably the most fundamental metric, the models perform unsatisfactorily overall, except for CRs representing thick storm clouds. Because model CR CF is internally constrained by our method, RFO discrepancies yield also substantial TCA errors. Our results support previous findings that CMIP5 models underestimate cloudiness. The multi-model mean performs well in matching observed RFO maps for many CRs, but is still not the best for this or other metrics. When overall performance across all CRs is assessed, some models, despite shortcomings, apparently outperform Moderate Resolution Imaging Spectroradiometer cloud observations evaluated against ISCCP like another model output. Lastly, contrasting cloud simulation performance against each model's equilibrium climate sensitivity in order to gain insight on whether good cloud simulation pairs with particular values of this parameter, yields no clear conclusions.

Cr2O3 ultrasmall nanoparticles filled carbon nanocapsules deriving from Cr(VI) for enhanced lithium storage

NASA Astrophysics Data System (ADS)

Zhao, Yun; Wang, Jianjiao; Ma, Canliang; Li, Yong

2018-07-01

Based on the considerations in environmental and economic benefits, Cr2O72- as the major chromium pollutant is employed for applications in energy storage. A novel Cr2O3 ultrasmall nanoparticles (NPs) (<5 nm) filled carbon nanocapsule configuration is achieved through a surfactant-free solvothermal route with renewable furfural as the carbon source. The confinement effect that Cr2O3 NPs are restrained in the outer robust carbon shell and the plenty space among Cr2O3 NPs result in substantially enhanced Li-storage performances, such as stable capacity of 568 mAh g-1 at 100 mA g-1 after more than 200 cycles and high capacity retention at large current density.

Caloric restriction coupled with radiation decreases metastatic burden in triple negative breast cancer.

PubMed

Simone, Brittany A; Dan, Tu; Palagani, Ajay; Jin, Lianjin; Han, Sunny Y; Wright, Christopher; Savage, Jason E; Gitman, Robert; Lim, Meng Kieng; Palazzo, Juan; Mehta, Minesh P; Simone, Nicole L

2016-09-01

Metastatic breast cancer is devastating and triple negative breast cancers (TNBC) have a higher propensity for metastasis. Improved local control upfront in this aggressive cancer could potentially decrease its propensity toward metastasis. We sought to determine if using caloric restriction (CR) as a systemic therapy, combined with radiation therapy (IR) to the primary tumor, may impact metastatic disease. An orthotopic mouse model using a highly metastatic, luciferase-tagged TNBC cell line (4T1), was used to generate palpable tumors. Mice were then treated with CR, IR, and a combination of the two. In vivo imaging was performed for metastatic evaluation. Molecular evaluation of the tumors was performed, generating a mechanistic hypothesis for CR, which was then tested with pertinent pathway inhibition in the model. CR significantly increased the time to developing metastases, decreased the overall number and volume of lung metastases, and increased survival. CR decreased proliferation, increased apoptosis and globally downregulated the IGF-1R signaling pathway. Adding an IGF-1R/INSR inhibitor to local IR in vivo accomplished a decrease in metastases similar to CR plus IR, demonstrating the importance of the IGF-1R signaling pathway, and underscoring it as a possible mechanism for CR. CR decreased metastatic burden and therefore may complement cytotoxic therapies being used in the clinical setting for metastatic disease. Downregulation of the IGF-1R pathway, is in part responsible for this response and modulating IGF-1R directly resulted in similar improved progression-free survival. The novel use of CR has the potential to enhance clinical outcomes for patients with metastatic breast cancer.

Cognitive reserve is associated with the functional organization of the brain in healthy aging: a MEG study

PubMed Central

López, María E.; Aurtenetxe, Sara; Pereda, Ernesto; Cuesta, Pablo; Castellanos, Nazareth P.; Bruña, Ricardo; Niso, Guiomar; Maestú, Fernando; Bajo, Ricardo

2014-01-01

The proportion of elderly people in the population has increased rapidly in the last century and consequently “healthy aging” is expected to become a critical area of research in neuroscience. Evidence reveals how healthy aging depends on three main behavioral factors: social lifestyle, cognitive activity, and physical activity. In this study, we focused on the role of cognitive activity, concentrating specifically on educational and occupational attainment factors, which were considered two of the main pillars of cognitive reserve (CR). Twenty-one subjects with similar rates of social lifestyle, physical and cognitive activity were selected from a sample of 55 healthy adults. These subjects were divided into two groups according to their level of CR; one group comprised subjects with high CR (9 members) and the other one contained those with low CR (12 members). To evaluate the cortical brain connectivity network, all participants were recorded by Magnetoencephalography (MEG) while they performed a memory task (modified version of the Sternberg's Task). We then applied two algorithms [Phase Locking Value (PLV) and Phase Lag Index (PLI)] to study the dynamics of functional connectivity. In response to the same task, the subjects with lower CR presented higher functional connectivity than those with higher CR. These results may indicate that participants with low CR needed a greater “effort” than those with high CR to achieve the same level of cognitive performance. Therefore, we conclude that CR contributes to the modulation of the functional connectivity patterns of the aging brain. PMID:24982632

Reliability of abstracting performance measures: results of the cardiac rehabilitation referral and reliability (CR3) project.

PubMed

Thomas, Randal J; Chiu, Jensen S; Goff, David C; King, Marjorie; Lahr, Brian; Lichtman, Steven W; Lui, Karen; Pack, Quinn R; Shahriary, Melanie

2014-01-01

Assessment of the reliability of performance measure (PM) abstraction is an important step in PM validation. Reliability has not been previously assessed for abstracting PMs for the referral of patients to cardiac rehabilitation (CR) and secondary prevention (SP) programs. To help validate these PMs, we carried out a multicenter assessment of their reliability. Hospitals and clinical practices from around the United States were invited to participate in the Cardiac Rehabilitation Referral Reliability (CR3) Project. Twenty-nine hospitals and 23 outpatient centers expressed interest in participating. Seven hospitals and 6 outpatient centers met participation criteria and submitted completed data. Site coordinators identified 35 patients whose charts were reviewed by 2 site abstractors twice, 1 week apart. Percent agreement and the Cohen κ statistic were used to describe intra- and interabstractor reliability for patient eligibility for CR/SP, patient exceptions for CR/SP referral, and documented referral to CR/SP. Results were obtained from within-site data, as well as from pooled data of all inpatient and all outpatient sites. We found that intra-abstractor reliability reflected excellent repeatability (≥ 90% agreement; κ ≥ 0.75) for ratings of CR/SP eligibility, exceptions, and referral, both from pooled and site-specific analyses of inpatient and outpatient data. Similarly, the interabstractor agreement from pooled analysis ranged from good to excellent for the 3 items, although with slightly lower measures of reliability. Abstraction of PMs for CR/SP referral has high reliability, supporting the use of these PMs in quality improvement initiatives aimed at increasing CR/SP delivery to patients with cardiovascular disease.

Lack of supervision after residential cardiac rehabilitation increases cardiovascular risk factors.

PubMed

Berent, Robert; von Duvillard, Serge P; Auer, Johann; Sinzinger, Helmut; Schmid, Peter

2010-06-01

Cardiovascular rehabilitation (CR) is an important component of care for patients with cardiovascular disease (CVD) and has been well documented and promoted by various health organizations and position statements worldwide. The purpose of this study was to investigate whether patients readmitted to CR on average 16 months after their previous discharge, maintained the reduction in CVD risk factors, maintained or improved functional capacity, occurrence of adverse cardiovascular events, and possible modifications in prescribed medications. Five hundred and seventy patients (60+/-10 years) underwent cycle ergometry and blood sampling at the beginning, the end of 21+/-2 days of the previous CR, and again at readmission to CR. The CR consisted of cycling for 17+/-4 min at frequency of six times a week and daily walking for 45 min at 60-70% of the maximal individual heart rate. Blood total cholesterol, low-density lipoprotein-cholesterol, triglycerides, and body mass index decreased significantly during CR. Resting blood pressure, maximal performance (watts), maximal oxygen uptake, and heart rate recovery improved significantly in 1 min (P<0.001). At readmission, all traditional CVD risk factors increased significantly, although medication was unchanged and angiotensin-converting enzyme inhibitors were partly replaced by angiotensin II receptor antagonists. Exercise performance remained unchanged. At readmission, we observed an increase in CVD risk factors, although, physical fitness remained stable. Thus, failure of lifestyle modification after CR indicates the cause for concern. Reinforcement of home setting sessions of CR patients or other strategies to enhance long-term compliance to lifestyle changes could reduce the observed attrition in CR benefits.

The effects of Creatine Long-Term Supplementation on Muscle Morphology and Swimming Performance in Rats

PubMed Central

Yildiz, Ahmet; Ozdemir, Ercan; Gulturk, Sefa; Erdal, Sena

2009-01-01

Creatine (Cr) has been shown to increase the total muscle mass. The purpose of this study was to investigate the effect of Cr supplementation on muscle morphology and swimming performance, using an animal model. Each rat was subjected to exercise 15-minute period daily for the 12 weeks. The rats were randomly divided into four groups: no Cr supplementation (CON), no Cr supplementation and incomplete food intake (lacking lysine and methionine in diet for rats) (INCO), Cr supplementation 1 g·kg-1·day-1 (CREAT-I) and Cr supplementation 2 g·kg-1·day-1 (CREAT-II). Three months later, all groups adult rats exercised in swimming pool chambers. Swimming time was recorded as minute for each rat. Following swimming performance period, the animals were killed by cervical dislocation and the gastrocnemius and diaphragm muscles were dissected. Serial slices of 5-7 μm were allocated paraffin wax and histochemical staining procedure of cross-sections was carried out with heamatoxylin-eosin technics. All groups gained body weight at the end of 12 weeks but there was no statistical difference among them. Swimming time values were statistical difference between CREAT-II and CON group as well as between CREAT-I and CON group (p < 0.05). In the INCO group was determined increased connective tissue cell of the muscle sample. In contrast, in the CREAT-I and CREAT-II group, the basic histological changes were large-scale muscle fibers and hypertrophic muscle cells. These results suggest that long-term creatine supplementation increased the number of muscle fibers and enhanced endurance swimming performance in rats. Key points There is no study about the effects of creatine long-term supplementation on muscle morphology and swimming performance in rats. Long-term creatine supplementation increase muscle hypertrophy (but not body weight) and enhance endurance swimming performance in rats. The quantitative analysis indicated that the number of muscle fibers per defined area increased in creatine supplementation groups. PMID:24149591

Database on Performance of Neutron Irradiated FeCrAl Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Field, Kevin G.; Briggs, Samuel A.; Littrell, Ken

The present report summarizes and discusses the database on radiation tolerance for Generation I, Generation II, and commercial FeCrAl alloys. This database has been built upon mechanical testing and microstructural characterization on selected alloys irradiated within the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) up to doses of 13.8 dpa at temperatures ranging from 200°C to 550°C. The structure and performance of these irradiated alloys were characterized using advanced microstructural characterization techniques and mechanical testing. The primary objective of developing this database is to enhance the rapid development of a mechanistic understanding on the radiation tolerancemore » of FeCrAl alloys, thereby enabling informed decisions on the optimization of composition and microstructure of FeCrAl alloys for application as an accident tolerant fuel (ATF) cladding. This report is structured to provide a brief summary of critical results related to the database on radiation tolerance of FeCrAl alloys.« less

Diffusion of cations in chromia layers grown on iron-base alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lobnig, R.E.; Hennesen, K.; Grabke, H.J.

Diffusion of the cations Cr, Fe, Mn, and Ni in Cr{sub 2}O{sub 3} has been investigated at 1,173 K. The diffusion measurements were performed on chromia layers grown on the model alloys Fe-20Cr and Fe-20Cr-12Ni in order to consider effects of small amounts of dissolved alien cations in Cr{sub 2}O{sub 3}. The samples were diffusion annealed in H{sub 2}-H{sub 2}O at an oxygen partial pressure close to the Cr{sub 2}O{sub 3}/Cr equilibrium. For all tracers the lattice-diffusion coefficients are 3-5 orders of magnitude smaller than the grain-boundary diffusion coefficients. The lattice diffusivity of Mn is about two orders of magnitudemore » greater than the other lattice-diffusion coefficients, especially in Cr{sub 2}O{sub 3} grown on Fe-20Cr-12Ni. The values of the diffusion coefficients for Cr, Fe, and Ni are in the same range. Diffusion of the tracers in Cr{sub 2}O{sub 3} grown on different alloys did not show significant differences with the exception of Mn.« less

Chromium Oxidation State in Planetary Basalts: Oxygen Fugacity Indicator and Critical Variable for Cr-Spinel Stability

NASA Technical Reports Server (NTRS)

Bell, A. S.; Burger, P. V.; Le, Loan; Papike, J. J.; Jone, J.; Shearer, C. K.

2014-01-01

Cr is a ubiquitous and relatively abundant minor element in basaltic, planetary magmas. At the reduced oxidation states (

High creatinine clearance in critically ill patients with community-acquired acute infectious meningitis.

PubMed

Lautrette, Alexandre; Phan, Thuy-Nga; Ouchchane, Lemlih; Aithssain, Ali; Tixier, Vincent; Heng, Anne-Elisabeth; Souweine, Bertrand

2012-09-27

A high dose of anti-infective agents is recommended when treating infectious meningitis. High creatinine clearance (CrCl) may affect the pharmacokinetic / pharmacodynamic relationships of anti-infective drugs eliminated by the kidneys. We recorded the incidence of high CrCl in intensive care unit (ICU) patients admitted with meningitis and assessed the diagnostic accuracy of two common methods used to identify high CrCl. Observational study performed in consecutive patients admitted with community-acquired acute infectious meningitis (defined by >7 white blood cells/mm3 in cerebral spinal fluid) between January 2006 and December 2009 to one medical ICU. During the first 7 days following ICU admission, CrCl was measured from 24-hr urine samples (24-hr-UV/P creatinine) and estimated according to Cockcroft-Gault formula and the simplified Modification of Diet in Renal Disease (MDRD) equation. High CrCl was defined as CrCl >140 ml/min/1.73 m2 by 24-hr-UV/P creatinine. Diagnostic accuracy was performed with ROC curves analysis. Thirty two patients were included. High CrCl was present in 8 patients (25%) on ICU admission and in 15 patients (47%) during the first 7 ICU days for a median duration of 3 (1-4) days. For the Cockcroft-Gault formula, the best threshold to predict high CrCl was 101 ml/min/1.73 m2 (sensitivity: 0.96, specificity: 0.75, AUC = 0.90 ± 0.03) with a negative likelihood ratio of 0.06. For the simplified MDRD equation, the best threshold to predict high CrCl was 108 ml/min/1.73 m2 (sensitivity: 0.91, specificity: 0.80, AUC = 0.88 ± 0.03) with a negative likelihood ratio of 0.11. There was no difference between the estimated methods in the diagnostic accuracy of identifying high CrCl (p = 0.30). High CrCl is frequently observed in ICU patients admitted with community-acquired acute infectious meningitis. The estimated methods of CrCl could be used as a screening tool to identify high CrCl.

Effects of chromium nanoparticle dosage on growth, body composition, serum hormones and tissue chromium in Sprague-Dawley rats*

PubMed Central

Zha, Long-ying; Xu, Zi-rong; Wang, Min-qi; Gu, Liang-ying

2007-01-01

This 6-week study was conducted to evaluate the effects of seven different levels of dietary chromium (Cr) (0, 75, 150, 300, 450, 600, and 1 200 ppb Cr) in the form of Cr nanoparticle (CrNano) on growth, body composition, serum hormones and tissue Cr in Sprague-Dawley (SD) rats. Seventy male SD rats (average initial body weight of (83.2±4.4) g) were randomly assigned to seven dietary treatments (n=10). At the end of the trial, body composition was assessed via dual energy X-ray absorptiometry (DEXA). All rats were then sacrificed to collect samples of blood, organs and tissues for determination of serum hormones and tissue Cr contents. The results indicated that lean body mass was significantly increased (P<0.05) due to the addition of 300 and 450 ppb Cr from CrNano. Supplementation of 150, 300, 450, and 600 ppb Cr decreased (P<0.05) percent body fat significantly. Average daily gain was increased (P<0.05) by addition of 75, 150, and 300 ppb Cr and feed efficiency was increased (P<0.05) by supplementation of 75, 300, and 450 ppb Cr. Addition of 300 and 450 ppb Cr decreased (P<0.05) the insulin level in serum greatly. Cr contents in liver and kidney were greatly increased (P<0.05) by the addition of Cr as CrNano in the dosage of from 150 ppb to 1 200 ppb. In addition, Supplementation of 300, 450, and 600 ppb Cr significantly increased (P<0.05) Cr content in the hind leg muscle. These results suggest that supplemental CrNano has beneficial effects on growth performance and body composition, and increases tissue Cr concentration in selected muscles. PMID:17542060

Enhanced performance of hexavalent chromium reducing cathodes in the presence of Shewanella oneidensis MR-1 and lactate.

PubMed

Xafenias, Nikolaos; Zhang, Yue; Banks, Charles J

2013-05-07

Biocathodes for the reduction of the highly toxic hexavalent chromium (Cr(VI)) were investigated using Shewanella oneidensis MR-1 (MR-1) as a biocatalyst and performance was assessed in terms of current production and Cr(VI) reduction. Potentiostatically controlled experiments (-500 mV vs Ag/AgCl) showed that a mediatorless MR-1 biocathode started up under aerated conditions in the presence of lactate, received 5.5 and 1.7 times more electrons for Cr(VI) reduction over a 4 h operating period than controls without lactate and with lactate but without MR-1, respectively. Cr(VI) reduction was also enhanced, with a decrease in concentration over the 4 h operating period of 9 mg/L Cr(VI), compared to only 1 and 3 mg/L, respectively, in the controls. Riboflavin, an electron shuttle mediator naturally produced by MR-1, was also found to have a positive impact in potentiostatically controlled cathodes. Additionally, a microbial fuel cell (MFC) with MR-1 and lactate present in both anode and cathode produced a maximum current density of 32.5 mA/m(2) (1000 Ω external load) after receiving a 10 mg/L Cr(VI) addition in the cathode, and cathodic efficiency increased steadily over an 8 day operation period with successive Cr(VI) additions. In conclusion, effective and continuous Cr(VI) reduction with associated current production were achieved when MR-1 and lactate were both present in the biocathodes.

A national survey of cardiac rehabilitation services in New Zealand: 2015.

PubMed

Kira, Geoff; Doolan-Noble, Fiona; Humphreys, Grace; Williams, Gina; O'Shaughnessy, Helen; Devlin, Gerry

2016-05-27

Guidelines for cardiac rehabilitation (CR) programmes inform best practice. In Aotearoa NewZealand, little information exists about the structure and services provided by CR programmes and there is a poor understanding of how existing CR programmes are delivered with respect to evidence-based national guidelines. All 46 CR providers in New Zealand were invited to participate in a national survey in 2015. The survey sought information on the following: unit structure; referral processes; patient assessment; audit (including quality assurance activity); Phase 2 CR content; and support for special populations. Simple descriptive analysis of the responses was conducted, involving forming counts and percentages. Thirty-six distinct units completed the survey and 94% provided Phase 2. Assessment tools, Phase 2 educational components, and the methods of providing the exercise component varied. Most units audited their services, 25% audited their programme six-monthly or more frequently. Just over half of the units (56%) reported key performance indicators. The survey identified variations in delivery and content of CR in New Zealand, with poor understanding of the impact on patient outcomes. This is likely due to the absence of standardised audit practices and routine collection of key performance indicators on a national basis.

Cognitive Readiness Assessment and Reporting: An Open Source Mobile Framework for Operational Decision Support and Performance Improvement

ERIC Educational Resources Information Center

Heric, Matthew; Carter, Jenn

2011-01-01

Cognitive readiness (CR) and performance for operational time-critical environments are continuing points of focus for military and academic communities. In response to this need, we designed an open source interactive CR assessment application as a highly adaptive and efficient open source testing administration and analysis tool. It is capable…

Importance of doping and frustration in itinerant Fe-doped Cr 2Al

DOE PAGES

Susner, M. A.; Parker, D. S.; Sefat, A. S.

2015-05-12

We performed an experimental and theoretical study comparing the effects of Fe-doping of Cr 2Al, an antiferromagnet with a N el temperature of 670 K, with known results on Fe-doping of antiferromagnetic bcc Cr. (Cr 1-xFe x) 2Al materials are found to exhibit a rapid suppression of antiferromagnetic order with the presence of Fe, decreasing T N to 170 K for x=0.10. Antiferromagnetic behavior disappears entirely at x≈0.125 after which point increasing paramagnetic behavior is exhibited. Moreover, this is unlike the effects of Fe doping of bcc antiferromagnetic Cr, in which T N gradually decreases followed by the appearance ofmore » a ferromagnetic state. Theoretical calculations explain that the Cr 2Al-Fe suppression of magnetic order originates from two effects: the first is band narrowing caused by doping of additional electrons from Fe substitution that weakens itinerant magnetism; the second is magnetic frustration of the Cr itinerant moments in Fe-substituted Cr 2Al. In pure-phase Cr 2Al, the Cr moments have an antiparallel alignment; however, these are destroyed through Fe substitution and the preference of Fe for parallel alignment with Cr. This is unlike bulk Fe-doped Cr alloys in which the Fe anti-aligns with the Cr atoms, and speaks to the importance of the Al atoms in the magnetic structure of Cr 2Al and Fe-doped Cr 2Al.« less

Monitoring creatine and phosphocreatine by (13)C MR spectroscopic imaging during and after (13)C4 creatine loading: a feasibility study.

PubMed

Janssen, Barbara H; Lassche, Saskia; Hopman, Maria T; Wevers, Ron A; van Engelen, Baziel G M; Heerschap, Arend

2016-08-01

Creatine (Cr) supplementation to enhance muscle performance shows variable responses among individuals and different muscles. Direct monitoring of the supplied Cr in muscles would address these differences. In this feasibility study, we introduce in vivo 3D (13)C MR spectroscopic imaging (MRSI) of the leg with oral ingestion of (13)C4-creatine to observe simultaneously Cr and phosphocreatine (PCr) for assessing Cr uptake, turnover, and the ratio PCr over total Cr (TCr) in individual muscles. (13)C MRSI was performed of five muscles in the posterior thigh in seven subjects (two males and two females of ~20 years, one 82-year-old male, and two neuromuscular patients) with a (1)H/(13)C coil in a 3T MR system before, during and after intake of 15 % (13)C4-enriched Cr. Subjects ingested 20 g Cr/day for 4 days in four 5 g doses at equal time intervals. The PCr/TCr did not vary significantly during supplementation and was similar for all subjects and investigated muscles (average 0.71 ± 0.07), except for the adductor magnus (0.64 ± 0.03). The average Cr turnover rate, assessed in male muscles, was 2.1 ± 0.7 %/day. The linear uptake rates of Cr were variable between muscles, although not significantly different. This assessment was possible in all investigated muscles of young male volunteers, but less so in muscles of the other subjects due to lower signal-to-noise ratio. Improvements for future studies are discussed. In vivo (13)C MRSI after (13)C-Cr ingestion is demonstrated for longitudinal studies of Cr uptake, turnover, and PCr/TCr ratios of individual muscles in one exam.

The usefulness of rapid point-of-care creatinine testing for the prevention of contrast-induced nephropathy in the emergency department.

PubMed

You, Je Sung; Chung, Yong Eun; Park, Jong Woo; Lee, Woonhyoung; Lee, Hye-Jeong; Chung, Tae Nyoung; Chung, Sung Phil; Park, Incheol; Kim, Seungho

2013-07-01

Renal dysfunction is the most important factor to consider when predicting a patient's risk of developing contrast-induced nephropathy (CIN). Measurement of creatinine (Cr) via rapid point-of-care blood urea nitrogen/creatinine testing (POCT-BUN/Cr) to determine CIN risk could potentially reduce the time required to achieve an accurate diagnosis and to initiate and complete treatment in the emergency department (ED). The aim of our study was to compare the results of POCT-BUN/Cr and reference laboratory tests for BUN and serum Cr. A retrospective analysis of suspected stroke patients who presented between November 2009 and November 2010, and had BUN and Cr levels measured by POCT-BUN/Cr, and the reference laboratory tests performed with the blood sample which was transferred to the central laboratory by an air-shoot system. Two assays were conducted on the whole blood (POCT) and serum (reference) by trained technicians. The time interval from arrival at the ED to reporting of the results was assessed for both assays via a computerised physician order entry system. The mean standard deviation (SD) interval from arrival at the ED to reporting of the results was 11.4 (4.9) min for POCT-BUN/Cr and 46.8 (38.5) min for the serum reference laboratory tests (p<0.001). Intra-class correlation coefficient (ICC) analysis demonstrated a high level of agreement (the consistency agreement) between POCT and the serum reference tests for both BUN (ICC=0.914) and Cr (ICC=0.980). This study suggests that POCT-BUN/Cr results correlate well with those of serum reference tests in terms of BUN and Cr levels and, in turn, predicting CIN. POCT-BUN/Cr is easily performed with a rapid turnaround time, suggesting its use in the ED may have substantial clinical benefit.

Facile preparation of magnetic mesoporous MnFe2O4@SiO2-CTAB composites for Cr(VI) adsorption and reduction.

PubMed

Li, Na; Fu, Fenglian; Lu, Jianwei; Ding, Zecong; Tang, Bing; Pang, Jiabin

2017-01-01

Chromium-contaminated water is regarded as one of the biggest threats to human health. In this study, a novel magnetic mesoporous MnFe 2 O 4 @SiO 2 -CTAB composite was prepared by a facile one-step modification method and applied to remove Cr(VI). X-ray diffraction, scanning electron microscopy, transmission electron microscopy, specific surface area, and vibrating sample magnetometer were used to characterize MnFe 2 O 4 @SiO 2 -CTAB composites. The morphology analysis showed that the composites displayed a core-shell structure. The outer shell was mesoporous silica with CTAB and the core was MnFe 2 O 4 nanoparticles, which ensured the easy separation by an external magnetic field. The performance of MnFe 2 O 4 @SiO 2 -CTAB composites in Cr(VI) removal was far better than that of bare MnFe 2 O 4 nanoparticles. There were two reasons for the effective removal of Cr(VI) by MnFe 2 O 4 @SiO 2 -CTAB composites: (1) mesoporous silica shell with abundant CTA + significantly enhanced the Cr(VI) adsorption capacity of the composites; (2) a portion of Cr(VI) was reduced to less toxic Cr(III) by MnFe 2 O 4 , followed by Cr(III) immobilized on MnFe 2 O 4 @SiO 2 -CTAB composites, which had been demonstrated by X-ray photoelectron spectroscopy results. The adsorption of Cr(VI) onto MnFe 2 O 4 @SiO 2 -CTAB followed the Freundlich isotherm model and pseudo-second-order model. Tests on the regeneration and reuse of the composites were performed. The removal efficiency of Cr(VI) still retained 92.4% in the sixth cycle. MnFe 2 O 4 @SiO 2 -CTAB composites exhibited a great potential for the removal of Cr(VI) from water. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of Dietary Chromium Methionine on Growth Performance, Carcass Composition, Meat Colour and Expression of the Colour-related Gene Myoglobin of Growing-finishing Pigs

PubMed Central

Li, Y. S.; Zhu, N. H.; Niu, P. P.; Shi, F. X.; Hughes, C. L.; Tian, G. X.; Huang, R. H.

2013-01-01

To investigate the effect of dietary chromium (Cr) as Cr methionine (CrMet) on growth performance, carcass traits, pork quality, meat colour and expression of meat colour-related genes in growing-finishing pigs, 189 crossbred Duroc×(Landrace×Yorkshire) growing-finishing pigs (male, castrated, average initial BW 74.58±1.52 kg) were selected and randomly allocated into four groups. Dietary treatments per kg of feed were as follows: 0 (CT), 0.3 mg/kg (T1), 0.6 mg/kg (T2) and 0.9 mg/kg (T3) Cr (in the form of CrMet; as-fed basis), and each treatment was replicated five times with 8 to 10 pigs per replicate pen. During the 28 d of the experiment, both the ADG and the ADFI increased linearly (p<0.05) as the level of dietary Cr increased. The F/G ratio decreased linearly (p<0.05). As dietary Cr increased, loin muscle areas (linear, p = 0.013) and average backfat thickness (linear, p = 0.072) decreased. Shear force (linear, p = 0.070) and Commission Internationale de I’Éclairage (CIE) redness (quadratic, p = 0.028) were increased. In addition, CIE Lightness (quadratic, p = 0.053) were decreased as dietary Cr increased. As dietary Cr increased, total myglobin (Mb) content (quadratic, p = 0.015) and the mb mRNA levels (quadratic, p = 0.046) in longissimus muscles of pigs were up-regulated. In conclusion, supplementation of dietary Cr improved growth and meat colour, but increased shear force and decreased IMF reduced palatability of longissimus muscles. Moreover, the increasing total Mb content and mb mRNA levels indicated that CrMet dietary supplementation may improve meat colour via up-regulating expression of the mb gene. PMID:25049881

Development and application of a method for Cr(III) determination in dairy products by HPLC-ICP-MS.

PubMed

Hernandez, Fanny; Jitaru, Petru; Cormant, Florence; Noël, Laurent; Guérin, Thierry

2018-02-01

This study describes the development of an analytical approach for the determination of Cr(III) in dairy products by microwave assisted extraction, complexation in situ by ethylenediaminetetraacetate (EDTA) and high performance liquid chromatography hyphenated to inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). The extraction step was optimised by using an experimental design. A limit of quantification of 38µgkg -1 dry weight (d.w.) was obtained whereas the bias (%) measured ranged from 10 to 18%. The repeatability and intermediate precision varied between 1.2-5.0% and 7.5-13.5%, respectively. The method was applied to the analysis of several dairy samples beforehand characterized in terms of Cr(VI) and total chromium (Cr total ). Cr(III) concentrations ranged from <13 to 255µgkg -1 d.w. The results showed a good agreement between Cr(III) and Cr total concentration levels. Copyright © 2017 Elsevier Ltd. All rights reserved.

Diffusion-weighted imaging: Apparent diffusion coefficient histogram analysis for detecting pathologic complete response to chemoradiotherapy in locally advanced rectal cancer.

PubMed

Choi, Moon Hyung; Oh, Soon Nam; Rha, Sung Eun; Choi, Joon-Il; Lee, Sung Hak; Jang, Hong Seok; Kim, Jun-Gi; Grimm, Robert; Son, Yohan

2016-07-01

To investigate the usefulness of apparent diffusion coefficient (ADC) values derived from histogram analysis of the whole rectal cancer as a quantitative parameter to evaluate pathologic complete response (pCR) on preoperative magnetic resonance imaging (MRI). We enrolled a total of 86 consecutive patients who had undergone surgery for rectal cancer after neoadjuvant chemoradiotherapy (CRT) at our institution between July 2012 and November 2014. Two radiologists who were blinded to the final pathological results reviewed post-CRT MRI to evaluate tumor stage. Quantitative image analysis was performed using T2 -weighted and diffusion-weighted images independently by two radiologists using dedicated software that performed histogram analysis to assess the distribution of ADC in the whole tumor. After surgery, 16 patients were confirmed to have achieved pCR (18.6%). All parameters from pre- and post-CRT ADC histogram showed good or excellent agreement between two readers. The minimum, 10th, 25th, 50th, and 75th percentile and mean ADC from post-CRT ADC histogram were significantly higher in the pCR group than in the non-pCR group for both readers. The 25th percentile value from ADC histogram in post-CRT MRI had the best diagnostic performance for detecting pCR, with an area under the receiver operating characteristic curve of 0.796. Low percentile values derived from the ADC histogram analysis of rectal cancer on MRI after CRT showed a significant difference between pCR and non-pCR groups, demonstrating the utility of the ADC value as a quantitative and objective marker to evaluate complete pathologic response to preoperative CRT in rectal cancer. J. Magn. Reson. Imaging 2016;44:212-220. © 2015 Wiley Periodicals, Inc.

Analysis of spastic gait in cervical myelopathy: Linking compression ratio to spatiotemporal and pedobarographic parameters.

PubMed

Nagai, Taro; Takahashi, Yasuhito; Endo, Kenji; Ikegami, Ryo; Ueno, Ryuichi; Yamamoto, Kengo

2018-01-01

Gait dysfunction associated with spasticity and hyperreflexia is a primary symptom in patients with compression of cervical spinal cord. The objective of this study was to link maximum compression ratio (CR) to spatiotemporal/pedobarographic parameters. Quantitative gait analysis was performed by using a pedobarograph in 75 elderly males with a wide range of cervical compression severity. CR values were characterized on T1-weighted magnetic resonance imaging (MRI). Statistical significances in gait analysis parameters (speed, cadence, stride length, step with, and toe-out angle) were evaluated among different CR groups by the non-parametric Kruskal-Wallis test followed by the Mann-Whitney U test using Bonferroni correction. The Spearman test was performed to verify correlations between CR and gait parameters. The Kruskal-Wallis test revealed significant decline in gait speed and stride length and significant increase in toe-out angle with progression of cervical compression myelopathy. The post-hoc Mann-Whitney U test showed significant differences in these parameters between the control group (0.45

Effects of dietary organic chromium and vitamin C supplementation on performance, immune responses, blood metabolites, and stress status of laying hens subjected to high stocking density.

PubMed

Mirfendereski, E; Jahanian, R

2015-02-01

The present study was carried out to investigate the effects of dietary supplementation of chromium-methionine (CrMet) and vitamin C (VC) on performance, immune response, and stress status of laying hens subjected to high stocking density. A total of 360 Hy-Line W-36 leghorn hens (at 26 wk old) were used in a 2×3×2 factorial arrangement that had 2 cage densities (5 and 7 hens per cage), 3 Cr levels (0, 500, and 1,000 ppb as CrMet), and 2 dietary VC levels (0 and 500 ppm as L-ascorbic acid). The trial lasted for 12 wk. The first 2 wk were for adaptation (26 to 28 wk of age), and the remaining 10 wk served as the main recording period. In addition to performance, immune response to Newcastle disease virus (NDV) was assessed at d 7 and 14 postvaccination. Also, the birds' stress status was evaluated by analyzing appropriate plasma metabolites. The results showed that hens in cages with higher stocking density had lower hen-day egg production, egg mass, and feed intake compared with those in normal density cages (P<0.05). Dietary CrMet supplementation caused significant increases in egg production and egg mass (P<0.01). There were significant Cr × VC interactions related to egg production and feed conversion efficiency (P<0.01); dietary CrMet supplementation was more effective in improving egg production and feed conversion ratio in VC-unsupplemented diets. Although plasma concentrations of triglycerides and high-density lipoproteins were not influenced by dietary treatments, supplemental CrMet decreased plasma cholesterol levels (P<0.05). Plasma insulin and glucose levels of hens kept at a density of 7 hens/cage were significantly higher than those of hens in normal cage density (P<0.01), and dietary CrMet supplementation decreased plasma concentrations of insulin (P<0.001) and glucose (P<0.01), with higher impacts in high stocking density-challenged hens. While high stocking density caused a marked increase in plasma corticosterone (P<0.01), both supplemental CrMet and VC decreased it to near normal levels. There were significant stocking density×Cr interactions related to plasma insulin and corticosterone concentrations (P<0.01); supplemental CrMet was more effective in lowering these hormones in high stocking density-challenged hens. The high stocking density challenge suppressed NDV antibody response (P<0.001), while dietary supplementation of CrMet improved antibody titers against NDV at d 14 post vaccination particularly in hens kept at a density of 7 hens/cage (P<0.01). From the present observations, it can be concluded that CrMet can improve laying performance largely because it alleviates harmful responses to stressful conditions. © 2015 Poultry Science Association Inc.

Advanced thin film thermocouples

NASA Technical Reports Server (NTRS)

Kreider, K. G.; Semancik, S.; Olson, C.

1984-01-01

The fabrication, materials characterization, and performance of thin film platinum rhodium thermocouples on gas turbine alloys was investigated. The materials chosen for the study were the turbine blade alloy systems MAR M200+Hf with NiCoCrAlY and FeCrAlY coatings, and vane alloy systems MAR M509 with FeCrAlY. Research was focussed on making improvements in the problem areas of coating substrate stability, adhesion, and insulation reliability and durability. Diffusion profiles between the substrate and coating with and without barrier coatings of Al2O3 are reported. The relationships between fabrication parameters of thermal oxidation and sputtering of the insulator and its characterization and performance are described. The best thin film thermocouples were fabricated with the NiCoCrAlY coatings which were thermally oxidized and sputter coated with Al2O3.

Cognitive performance in multiple sclerosis: the contribution of intellectual enrichment and brain MRI measures.

PubMed

Santangelo, Gabriella; Bisecco, Alvino; Trojano, Luigi; Sacco, Rosaria; Siciliano, Mattia; d'Ambrosio, Alessandro; Della Corte, Marida; Lavorgna, Luigi; Bonavita, Simona; Tedeschi, Gioacchino; Gallo, Antonio

2018-05-26

Cognitive reserve (CR) is a construct that originates from the observation of poor correspondence between brain damage and clinical symptoms. The aim of the study was to investigate the association between cognitive reserve (CR), brain reserve (BR) and cognitive functions and to evaluate whether CR might attenuate/moderate the negative impact of brain atrophy and lesion load on cognitive functions in multiple sclerosis (MS). To achieve these aims, ninety-eight relapsing-remitting MS patients underwent the brief repeatable battery of neuropsychological tests and Stroop test (ST). CR was assessed by vocabulary-based estimate of lifetime intellectual enrichment. All patients underwent a 3T MRI to assess T2-lesion load and atrophy measures, including normalized gray matter and white matter (nWMV) volumes. The BR was evaluated by maximal lifetime brain volume expressed by intracranial volume (ICV). Hierarchical regressions were used to investigate whether higher BR and/or CR is related to better cognitive performances after controlling for potentially confounding factors. The ICV was not associated with any cognitive tests. Intellectual enrichment was positively associated with performance on tests assessing memory, attention and information processing speed, verbal fluency and inhibitory control. Significant relationship between nWMV and ST was moderated by intellectual enrichment. In conclusion, the findings suggested that CR seems to mitigate cognitive dysfunction in MS patients and can reduce the negative impact of brain atrophy on inhibitory control, relevant for integrity of instrumental activities of daily living.

Locally advanced rectal cancer: post-chemoradiotherapy ADC histogram analysis for predicting a complete response.

PubMed

Cho, Seung Hyun; Kim, Gab Chul; Jang, Yun-Jin; Ryeom, Hunkyu; Kim, Hye Jung; Shin, Kyung-Min; Park, Jun Seok; Choi, Gyu-Seog; Kim, See Hyung

2015-09-01

The value of diffusion-weighted imaging (DWI) for reliable differentiation between pathologic complete response (pCR) and residual tumor is still unclear. Recently, a few studies reported that histogram analysis can be helpful to monitor the therapeutic response in various cancer research. To investigate whether post-chemoradiotherapy (CRT) apparent diffusion coefficient (ADC) histogram analysis can be helpful to predict a pCR in locally advanced rectal cancer (LARC). Fifty patients who underwent preoperative CRT followed by surgery were enrolled in this retrospective study, non-pCR (n = 41) and pCR (n = 9), respectively. ADC histogram analysis encompassing the whole tumor was performed on two post-CRT ADC600 and ADC1000 (b factors 0, 600 vs. 0, 1000 s/mm(2)) maps. Mean, minimum, maximum, SD, mode, 10th, 25th, 50th, 75th, 90th percentile ADCs, skewness, and kurtosis were derived. Diagnostic performance for predicting pCR was evaluated and compared. On both maps, 10th and 25th ADCs showed better diagnostic performance than that using mean ADC. Tenth percentile ADCs revealed the best diagnostic performance on both ADC600 (AZ 0.841, sensitivity 100%, specificity 70.7%) and ADC1000 (AZ 0.821, sensitivity 77.8%, specificity 87.8%) maps. In comparison between 10th percentile and mean ADC, the specificity was significantly improved on both ADC600 (70.7% vs. 53.7%; P = 0.031) and ADC1000 (87.8% vs. 73.2%; P = 0.039) maps. Post-CRT ADC histogram analysis is helpful for predicting pCR in LARC, especially, in improving the specificity, compared with mean ADC. © The Foundation Acta Radiologica 2014.

Effects of supplemental chromium picolinate and chromium nanoparticles on performance and antibody titers of infectious bronchitis and avian influenza of broiler chickens under heat stress condition.

PubMed

Hajializadeh, Farhad; Ghahri, Hasan; Talebi, Alireza

2017-01-01

This experiment was carried out to investigate the effects of different levels chromium picolinate (CrPic) and chromium nanoparticles (nano-Cr) on the performance and immune function of broilers under heat stress condition. A total of 320 Ross 308 broiler chicks (from 21 to 42 days) were assigned randomly into eight treatment groups (four replicates per treatment, and 10 chicks per replicate) and be reared at either thermoneutral (21 ˚C) or heat stress (36 ◦ C). The treatments were control (T1) group without supplementation and heat stress, T2 as a heat stress group without supplementation, T3, T4 and T5 groups which were supplemented with 500, 1000 and 1500 ppb CrPic in diet with heat stress, respectively and T6, T7 and T8 groups which were supplemented with 500, 1000 and 1500 ppb nano-chromium in diet under heat stress, respectively. Supplementation of chromium and nano-chromium improved performance including weight gain and feed conversion ratio of heat-stressed chickens. Antibody titers against avian influenza (AI) and infectious bronchitis (IB) at 21 to 42 days of age in broilers fed supplemental chromium and nano-chromium were higher than broiler chickens fed control diet ( p < 0.05). Nano-chromium supplementation at level of 1000 ppb and CrPic at level of 1500 ppb improved the antibody titers against AI and IB of broilers under heat stress conditions. It can be concluded from these findings that dietary supplementation of CrPic and nano-Cr can improve performance and antibody titers against AI and IB under heat stress conditions in broilers.

Descriptive Study Analyzing Discrepancies in a Software Development Project Change Request (CR) Assessment Process and Recommendations for Process Improvements

NASA Technical Reports Server (NTRS)

Cunningham, Kenneth J.

2002-01-01

The Change Request (CR) assessment process is essential in the display development cycle. The assessment process is performed to ensure that the changes stated in the description of the CR match the changes in the actual display requirements. If a discrepancy is found between the CR and the requirements, the CR must be returned to the originator for corrections. Data will be gathered from each of the developers to determine the type of discrepancies and the amount of time spent assessing each CR. This study will determine the most common types of discrepancies and the amount of time spent assessing those issues. The results of the study will provide a foundation for future improvements as well as a baseline for future studies.

Performance and Microstructure of a Novel Cr-Getter Material with LSCF-based Cells in a Generic Stack Test Fixture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chou, Yeong-Shyung; Choi, Jung-Pyung; Stevenson, Jeffry W.

In addition to developing passive means for Cr mitigation via coatings, Pacific Northwest National Laboratory has teamed up with the University of Connecticut to adopt an active approach by employing a novel Cr-getter material in the system. In this work, validation of the novel Cr-getter was conducted using cells in a generic stack test condition with humidified air and coated metallic interconnect. Two Cr-getter locations were investigated: one upstream and one “on cell.” Pre-oxidized AISI 441 metal stripes were used as Cr source. Three single cell tests were conducted at 800oC in constant current mode for 1000h with periodic stopsmore » for measurement of impedance and IV: a baseline cell, a cell with Cr source and getter, and a cell with Cr source but no getter. Results showed that the cell with Cr-getter degraded much slower (11.5% kh-1) than the baseline (15.3% kh-1) and the cell without the getter (56% kh-1).« less

Pathologic complete response and disease-free survival are not surrogate endpoints for 5-year survival in rectal cancer: an analysis of 22 randomized trials.

PubMed

Petrelli, Fausto; Borgonovo, Karen; Cabiddu, Mary; Ghilardi, Mara; Lonati, Veronica; Barni, Sandro

2017-02-01

We performed a literature-based analysis of randomized clinical trials to assess the pathologic complete response (pCR) (ypT0N0 after neoadjuvant therapy) and 3-year disease-free survival (DFS) as potential surrogate endpoints for 5-year overall survival (OS) in rectal cancer treated with neoadjuvant (chemo)radiotherapy (CT)RT. A systematic literature search of PubMed, EMBASE, the Web of Science, SCOPUS, CINAHL, and the Cochrane Library was performed. Treatment effects on 3-year DFS and 5-year OS were expressed as rates of patients alive (%), and those on pCR as differences in pCR rates (∆ pCR% ). A weighted regression analysis was performed at individual- and trial-level to test the association between treatment effects on surrogate (∆ pCR% and ∆ 3yDFS ) and the main clinical outcome (∆ 5yOS ). Twenty-two trials involving 10,050 patients, were included in the analysis. The individual level surrogacy showed that the pCR% and 3-year DFS were poorly correlated with 5-year OS (R=0.52; 95% CI, 0.31-0.91; P=0.002; and R=0.60; 95% CI, 0.36-1; P=0.002). The trial-level surrogacy analysis confirmed that the two treatment effects on surrogates (∆ pCR% and ∆ 3yDFS ) are not strong surrogates for treatment effects on 5-year OS % (R=0.2; 95% CI, -0.29-0.78; P=0.5 and R=0.64; 95% CI, 0.29-1; P=0.06). These findings were confirmed in neoadjuvant CTRT studies but not in phase III trials were 3-year DFS could still represent a valid surrogate. This analysis does not support the use of pCR and 3-year DFS% as appropriate surrogate endpoints for 5-year OS% in patients with rectal cancer treated with neoadjuvant therapy.

Structure and corrosion properties of PVD Cr-N coatings

NASA Astrophysics Data System (ADS)

Liu, C.; Bi, Q.; Ziegele, H.; Leyland, A.; Matthews, A.

2002-05-01

PVD Cr-N coatings produced by physical vapor deposition (PVD) are increasingly used for mechanical and tribological applications in various industrial sectors. These coatings are particularly attractive for their excellent corrosion resistance, which further enhances the lifetime and service quality of coated components. PVD Cr-N coated steels in an aqueous solution are usually corroded by galvanic attack via through-coating ``permeable'' defects (e.g., pores). Therefore, the corrosion performance of Cr-N coated steel is determined by a number of variables of the coating properties and corrosive environment. These variables include: (i) surface continuity and uniformity; (ii) through-coating porosity; (iii) film density and chemical stability; (iv) growth stresses; (v) interfacial and intermediate layers; (vi) coating thickness; (vii) coating composition; and (viii) substrate properties. In this article, PVD Cr-N coatings were prepared, by electron-beam PVD and sputter deposition, with different compositions, thicknesses, and surface roughnesses, by changing the N2 flow rate, applying multilayering techniques and changing the substrate finish prior to coating. The microstructure of such coatings is investigated by various analytical techniques such as glancing angle x-ray diffraction and scanning electron microscopy, which are also correlated with the corrosion performance of the coated steel. Both dc polarization and ac impedance spectroscopy were employed to investigate the corrosion resistance of Cr-N coated steel in a 0.5N NaCl solution. It has been found that the N2 flow rate during reactive deposition strongly determines the microstructure of Cr-N coatings (due to the changing nitrogen content in the film) and can thus affect the corrosion resistance of coated systems. The surface finish of the steel substrate also affects the uniformity and coverage of PVD coatings; grooves and inclusions on the original substrate can raise the susceptibility of coated systems to crevice corrosion. Increased coating thickness can also greatly reduce the incidence of through-coating porosity such that the improvement in corrosion performance of thicker Cr-N coatings is significant.

Neurocognitive function in HIV-infected persons with asymptomatic cryptococcal antigenemia: a comparison of three prospective cohorts.

PubMed

Montgomery, Martha P; Nakasujja, Noeline; Morawski, Bozena M; Rajasingham, Radha; Rhein, Joshua; Nalintya, Elizabeth; Williams, Darlisha A; Huppler Hullsiek, Kathy; Kiragga, Agnes; Rolfes, Melissa A; Donahue Carlson, Renee; Bahr, Nathan C; Birkenkamp, Kate E; Manabe, Yukari C; Bohjanen, Paul R; Kaplan, Jonathan E; Kambugu, Andrew; Meya, David B; Boulware, David R

2017-06-12

HIV-infected persons with detectable cryptococcal antigen (CrAg) in blood have increased morbidity and mortality compared with HIV-infected persons who are CrAg-negative. This study examined neurocognitive function among persons with asymptomatic cryptococcal antigenemia. Participants from three prospective HIV cohorts underwent neurocognitive testing at the time of antiretroviral therapy (ART) initiation. Cohorts included persons with cryptococcal meningitis (N = 90), asymptomatic CrAg + (N = 87), and HIV-infected persons without central nervous system infection (N = 125). Z-scores for each neurocognitive test were calculated relative to an HIV-negative Ugandan population with a composite quantitative neurocognitive performance Z-score (QNPZ-8) created from eight tested domains. Neurocognitive function was measured pre-ART for all three cohorts and additionally after 4 weeks of ART (and 6 weeks of pre-emptive fluconazole) treatment among asymptomatic CrAg + participants. Cryptococcal meningitis and asymptomatic CrAg + participants had lower median CD4 counts (17 and 26 cells/μL, respectively) than the HIV-infected control cohort (233 cells/μL) as well as lower Karnofsky performance status (60 and 70 vs. 90, respectively). The composite QNPZ-8 for asymptomatic CrAg + (-1.80 Z-score) fell between the cryptococcal meningitis cohort (-2.22 Z-score, P = 0.02) and HIV-infected controls (-1.36, P = 0.003). After four weeks of ART and six weeks of fluconazole, the asymptomatic CrAg + cohort neurocognitive performance improved (-1.0 Z-score, P < 0.001). Significant deficits in neurocognitive function were identified in asymptomatic CrAg + persons with advanced HIV/AIDS even without signs or sequelae of meningitis. Neurocognitive function in this group improves over time after initiation of pre-emptive fluconazole treatment and ART, but short term adherence support may be necessary.

Construction of a Cr3C2-C Peritectic Point Cell for Thermocouple Calibration

NASA Astrophysics Data System (ADS)

Ogura, Hideki; Deuze, Thierry; Morice, Ronan; Ridoux, Pascal; Filtz, Jean-Remy

The melting points of Cr3C2-C peritectic (1826°C) and Cr7C3-Cr3C2 eutectic (1742°C) alloys as materials for high-temperature fixed point cells are investigated for the use of thermocouple calibration. Pretests are performed to establish a suitable procedure for constructing contact thermometry cells based on such chromium-carbon mixtures. Two cells are constructed following two different possible procedures. The above two melting points are successfully observed for one of these cells using tungsten-rhenium alloy thermocouples.

Evaluation of a Cryptococcal antigen Lateral Flow Assay in serum and cerebrospinal fluid for rapid diagnosis of cryptococcosis in Colombia.

PubMed

Cáceres, Diego H; Zuluaga, Alejandra; Tabares, Ángela M; Chiller, Tom; González, Ángel; Gómez, Beatriz L

2017-12-21

A Lateral Flow Assay to detect cryptococcal antigen (CrAg® LFA) in serum and cerebrospinal fluid for the rapid diagnosis of cryptococcosis was evaluated. A retrospective validation was performed. Sensitivity and specificity of the CrAg® LFA was 100%. High concordance (kappa index=1.0) between Cryptococcal Antigen Latex Agglutination System (CALAS®) and CrAg® LFA was observed. CrAg® LFA showed higher analytical sensitivity for detecting low concentrations of cryptococcal antigen.

Evaluation of a Cryptococcal antigen Lateral Flow Assay in serum and cerebrospinal fluid for rapid diagnosis of cryptococcosis in Colombia

PubMed Central

Cáceres, Diego H.; Zuluaga, Alejandra; Tabares, Ángela M.; Chiller, Tom; González, Ángel; Gómez, Beatriz L.

2017-01-01

ABSTRACT A Lateral Flow Assay to detect cryptococcal antigen (CrAg® LFA) in serum and cerebrospinal fluid for the rapid diagnosis of cryptococcosis was evaluated. A retrospective validation was performed. Sensitivity and specificity of the CrAg® LFA was 100%. High concordance (kappa index=1.0) between Cryptococcal Antigen Latex Agglutination System (CALAS®) and CrAg® LFA was observed. CrAg® LFA showed higher analytical sensitivity for detecting low concentrations of cryptococcal antigen. PMID:29267584

Diffusibility Enhancement of Rejuvenator by Epoxidized Soybean Oil and Its Influence on the Performance of Recycled Hot Mix Asphalt Mixtures

PubMed Central

Kuang, Dongliang; Jiao, Yuan; Ye, Zhou; Lu, Zaihong; Chen, Huaxin; Yu, Jianying; liu, Ning

2018-01-01

Epoxidized soybean oil (ESO) was employed as a novel penetrant cooperating with a conventional rejuvenator (CR) for the recycling of reclaimed asphalt pavement (RAP). The influence of ESO on the diffusibility and the regenerating effects of CR on RAP were investigated. The diffusibility testing result shows that the diffusibility of CR is enhanced by the addition of ESO because the epoxy group in ESO can facilitate asphaltene dispersion due to its high polarity, which simultaneously reduces the viscosity and improves the fluidity of aged bitumen so as to allow diffusion of the rejuvenator into the aged bitumen. Road performance testing of a recycled hot mix asphalt mixture (RHMA) indicates that the fatigue and cracking resistance properties as well as the water stability of RHMA containing CR can be improved by the addition of ESO due to the diffusibility enhancement of CR, which boosts the regenerating effect of CR on aged bitumen in RAP. The fatigue and cracking resistance properties as well as the water stability of the recycled hot mix asphalt mixture containing CR with 7 wt % ESO approximate those of the hot mix asphalt mixture composed of the same virgin aggregates and bitumen. Taking into account the rutting resistance decline versus the addition of ESO, the content of ESO should not exceed 7 wt % of the conventional rejuvenator. PMID:29783675

Magnetic biochar combining adsorption and separation recycle for removal of chromium in aqueous solution.

PubMed

Xin, Ouyang; Yitong, Han; Xi, Cao; Jiawei, Chen

2017-03-01

Biochar has been developed in recent years for the removal of contaminants such as Cr (VI) in water. The enhancement of the adsorption capacity of biochar and its recyclable use are still challenges. In this study, magnetic biochar derived from corncobs and peanut hulls was synthesized under different pyrolysis temperatures after pretreating the biomass with a low concentration of 0.5 M FeCl 3 solution. The morphology, specific surface area, saturation magnetization and Fourier transform infrared spectroscopy (FT-IR) spectra were characterized for biochar. The magnetic biochar performed well in combining adsorption and separation recycle for the removal of Cr (VI) in water. The Cr (VI) adsorbance of the biochar was increased with the increase in pyrolysis temperature, and the magnetic biochar derived from corncobs showed better performance for both magnetization and removal of Cr (VI) than that from peanut hulls. The Langmuir model was used for the isothermal adsorption and the maximum Cr (VI) adsorption capacity of corncob magnetic biochar pyrolyzed at 650 °C reached 61.97 mg/g. An alkaline solution (0.1 M NaOH) favored the desorption of Cr (VI) from the magnetic biochar, and the removal of Cr (VI) still remained around 77.6% after four cycles of adsorption-desorption. The results showed that corncob derived magnetic biochar is a potentially efficient and recoverable adsorbent for remediation of heavy metals in water.

Diffusibility Enhancement of Rejuvenator by Epoxidized Soybean Oil and Its Influence on the Performance of Recycled Hot Mix Asphalt Mixtures.

PubMed

Kuang, Dongliang; Jiao, Yuan; Ye, Zhou; Lu, Zaihong; Chen, Huaxin; Yu, Jianying; Liu, Ning

2018-05-18

Epoxidized soybean oil (ESO) was employed as a novel penetrant cooperating with a conventional rejuvenator (CR) for the recycling of reclaimed asphalt pavement (RAP). The influence of ESO on the diffusibility and the regenerating effects of CR on RAP were investigated. The diffusibility testing result shows that the diffusibility of CR is enhanced by the addition of ESO because the epoxy group in ESO can facilitate asphaltene dispersion due to its high polarity, which simultaneously reduces the viscosity and improves the fluidity of aged bitumen so as to allow diffusion of the rejuvenator into the aged bitumen. Road performance testing of a recycled hot mix asphalt mixture (RHMA) indicates that the fatigue and cracking resistance properties as well as the water stability of RHMA containing CR can be improved by the addition of ESO due to the diffusibility enhancement of CR, which boosts the regenerating effect of CR on aged bitumen in RAP. The fatigue and cracking resistance properties as well as the water stability of the recycled hot mix asphalt mixture containing CR with 7 wt % ESO approximate those of the hot mix asphalt mixture composed of the same virgin aggregates and bitumen. Taking into account the rutting resistance decline versus the addition of ESO, the content of ESO should not exceed 7 wt % of the conventional rejuvenator.

The effects of dietary chromium(III) picolinate on growth performance, vital signs, and blood measurements of pigs during immune stress.

PubMed

Kim, Beob G; Lindemann, Merlin D; Cromwell, Gary L

2010-06-01

This experiment used 24 pigs (26.0 kg) to investigate the effects of dietary chromium (Cr) on pigs challenged with lipopolysaccharide (LPS). Following 35 days of diet exposure, the immune stress treatments were: (1) phosphate-buffered saline (PBS) injection and no Cr, (2) LPS injection and no Cr, (3) LPS injection and Cr 1,000 ppb, and (4) LPS injection and Cr 2,000 ppb. At 0 h, PBS or LPS was injected intraperitoneally in each pig. During the first 12 h post-injection, pigs challenged with LPS lost 951 g, while the PBS group gained 170 g (p < 0.001). Compared with the PBS group, LPS-challenged pigs consumed less feed (p < 0.01) during the first 24 h. The LPS group had higher rectal temperature at 2 and 4 h and higher respiratory rate at 1.3 and 8.5 h than the PBS group (p < 0.05). Plasma collected at 3 h had higher cortisol (p < 0.001) and lower glucose (p < 0.05) concentrations in the LPS group than the PBS group. However, supplemental Cr did not affect the response variables. Overall, the LPS challenge affects growth performance, vital signs, and plasma variables, but dietary Cr is unable to moderate stress-related effects associated with an LPS challenge.

Color record in self-monitoring of blood glucose improves glycemic control by better self-management.

PubMed

Nishimura, Akiko; Harashima, Shin-ichi; Honda, Ikumi; Shimizu, Yoshiyuki; Harada, Norio; Nagashima, Kazuaki; Hamasaki, Akihiro; Hosoda, Kiminori; Inagaki, Nobuya

2014-07-01

Color affects emotions, feelings, and behaviors. We hypothesized that color used in self-monitoring of blood glucose (SMBG) is helpful for patients to recognize and act on their glucose levels to improve glycemic control. Here, two color-indication methods, color record (CR) and color display (CD), were independently compared for their effects on glycemic control in less frequently insulin-treated type 2 diabetes. One hundred twenty outpatients were randomly allocated to four groups with 2×2 factorial design: CR or non-CR and CD or non-CD. Blood glucose levels were recorded in red or blue pencil in the CR arm, and a red or blue indicator light on the SMBG meter was lit in the CD arm, under hyperglycemia or hypoglycemia, respectively. The primary end point was difference in glycated hemoglobin (HbA1c) reduction in 24 weeks. Secondary end points were self-management performance change and psychological state change. HbA1c levels at 24 weeks were significantly decreased in the CR arm by -0.28% but were increased by 0.03% in the non-CR arm (P=0.044). In addition, diet and exercise scores were significantly improved in the CR arm compared with the non-CR arm. The exercise score showed significant improvement in the CD arm compared with the non-CD arm but without a significant difference in HbA1c reduction. Changes in psychological states were not altered between the arms. CR has a favorable effect on self-management performance without any influence on psychological stress, resulting in improved glycemic control in type 2 diabetes patients using less frequent insulin injection. Thus, active but not passive usage of color-indication methods by patients is important in successful SMBG.

Caloric restriction coupled with radiation decreases metastatic burden in triple negative breast cancer

PubMed Central

Simone, Brittany A.; Dan, Tu; Palagani, Ajay; Jin, Lianjin; Han, Sunny Y.; Wright, Christopher; Savage, Jason E.; Gitman, Robert; Lim, Meng Kieng; Palazzo, Juan; Mehta, Minesh P.; Simone, Nicole L.

2016-01-01

ABSTRACT Purpose: Metastatic breast cancer is devastating and triple negative breast cancers (TNBC) have a higher propensity for metastasis. Improved local control upfront in this aggressive cancer could potentially decrease its propensity toward metastasis. We sought to determine if using caloric restriction (CR) as a systemic therapy, combined with radiation therapy (IR) to the primary tumor, may impact metastatic disease. Methods: An orthotopic mouse model using a highly metastatic, luciferase-tagged TNBC cell line (4T1), was used to generate palpable tumors. Mice were then treated with CR, IR, and a combination of the two. In vivo imaging was performed for metastatic evaluation. Molecular evaluation of the tumors was performed, generating a mechanistic hypothesis for CR, which was then tested with pertinent pathway inhibition in the model. Results: CR significantly increased the time to developing metastases, decreased the overall number and volume of lung metastases, and increased survival. CR decreased proliferation, increased apoptosis and globally downregulated the IGF-1R signaling pathway. Adding an IGF-1R/INSR inhibitor to local IR in vivo accomplished a decrease in metastases similar to CR plus IR, demonstrating the importance of the IGF-1R signaling pathway, and underscoring it as a possible mechanism for CR. Conclusions: CR decreased metastatic burden and therefore may complement cytotoxic therapies being used in the clinical setting for metastatic disease. Downregulation of the IGF-1R pathway, is in part responsible for this response and modulating IGF-1R directly resulted in similar improved progression-free survival. The novel use of CR has the potential to enhance clinical outcomes for patients with metastatic breast cancer. PMID:27027731

Utilization of ICP/OES for the determination of trace metal binding to different humic fractions.

PubMed

de la Rosa, G; Peralta-Videa, J R; Gardea-Torresdey, J L

2003-02-28

In this study, the use of inductively coupled plasma/optical emission spectrometry (ICP/OES) to determine multi-metal binding to three biomasses, Sphagnum peat moss, humin and humic acids is reported. All the investigations were performed under part per billion (ppb) concentrations. Batch pH profile experiments were performed using multi-metal solutions of Cd(II), Cu(II), Pb(II), Ni(II), Cr(III) and Cr(VI). The results showed that at pH 2 and 3, the metal affinity of the three biomasses exposed to the multi-metal solution that included Cr(III) presented the following order: Cu(II), Pb(II)>Ni(II)>Cr(III)>Cd(II). On the other hand, when Cr(VI) was in the heavy metal mixture, Sphagnum peat moss and humin showed the following affinity: Cu(II), Pb(II)>Ni(II)>Cr(VI)>Cd(II); however, the affinity of the humic acids was: Cu(II)>Pb(II), Cr(VI)>Ni(II)>Cd(II). The results demonstrated that pH values of 4 and 5 were the most favorable for the heavy metal binding process. At pH 5, all the metals, except for Cr(VI), were bound between 90 and 100% to the three biomasses. However, the binding capacity of humic acids decreased at pH 6 in the presence of Cr(VI). The results showed that the ICP/OES permits the determination of heavy metal binding to organic matter at ppb concentration. These results will be very useful in understanding the role of humic substances in the fate and transport of heavy metals, and thus could provide information to develop new methodologies for the removal of low concentrations of toxic heavy metals from contaminated waters.

Improved scheme for Cross-track Infrared Sounder geolocation assessment and optimization

NASA Astrophysics Data System (ADS)

Wang, Likun; Zhang, Bin; Tremblay, Denis; Han, Yong

2017-01-01

An improved scheme for Cross-track Infrared Sounder (CrIS) geolocation assessment for all scan angles (from -48.5° to 48.5°) is developed in this study. The method uses spatially collocated radiance measurements from the Visible Infrared Imaging Radiometer Suite (VIIRS) image band I5 to evaluate the geolocation performance of the CrIS Sensor Data Records (SDR) by taking advantage of its high spatial resolution (375 m at nadir) and accurate geolocation. The basic idea is to perturb CrIS line-of-sight vectors along the in-track and cross-track directions to find a position where CrIS and VIIRS data matches more closely. The perturbation angles at this best matched position are then used to evaluate the CrIS geolocation accuracy. More importantly, the new method is capable of performing postlaunch on-orbit geometric calibration by optimizing mapping angle parameters based on the assessment results and thus can be further extended to the following CrIS sensors on new satellites. Finally, the proposed method is employed to evaluate the CrIS geolocation accuracy on current Suomi National Polar-orbiting Partnership satellite. The error characteristics are revealed along the scan positions in the in-track and cross-track directions. It is found that there are relatively large errors ( 4 km) in the cross-track direction close to the end of scan positions. With newly updated mapping angles, the geolocation accuracy is greatly improved for all scan positions (less than 0.3 km). This makes CrIS and VIIRS spatially align together and thus benefits the application that needs combination of CrIS and VIIRS measurements and products.

Regime-Based Evaluation of Cloudiness in CMIP5 Models

NASA Technical Reports Server (NTRS)

Jin, Daeho; Oraiopoulos, Lazaros; Lee, Dong Min

2016-01-01

The concept of Cloud Regimes (CRs) is used to develop a framework for evaluating the cloudiness of 12 fifth Coupled Model Intercomparison Project (CMIP5) models. Reference CRs come from existing global International Satellite Cloud Climatology Project (ISCCP) weather states. The evaluation is made possible by the implementation in several CMIP5 models of the ISCCP simulator generating for each gridcell daily joint histograms of cloud optical thickness and cloud top pressure. Model performance is assessed with several metrics such as CR global cloud fraction (CF), CR relative frequency of occurrence (RFO), their product (long-term average total cloud amount [TCA]), cross-correlations of CR RFO maps, and a metric of resemblance between model and ISCCP CRs. In terms of CR global RFO, arguably the most fundamental metric, the models perform unsatisfactorily overall, except for CRs representing thick storm clouds. Because model CR CF is internally constrained by our method, RFO discrepancies yield also substantial TCA errors. Our findings support previous studies showing that CMIP5 models underestimate cloudiness. The multi-model mean performs well in matching observed RFO maps for many CRs, but is not the best for this or other metrics. When overall performance across all CRs is assessed, some models, despite their shortcomings, apparently outperform Moderate Resolution Imaging Spectroradiometer (MODIS) cloud observations evaluated against ISCCP as if they were another model output. Lastly, cloud simulation performance is contrasted with each model's equilibrium climate sensitivity (ECS) in order to gain insight on whether good cloud simulation pairs with particular values of this parameter.

Low temperature oxidation synthesis of carbon encapsulated Cr2O3 nanocrystals and its lithium storage performance

NASA Astrophysics Data System (ADS)

Zhou, Yun; Liu, Boyang; Shao, Yingfeng; Fan, Chunhua; Fan, Runhua; Wen, Bosheng

A highly efficient and convenient strategy is developed for the one-step in-situ synthesis of carbon encapsulated Cr2O3 nanocrystals with core-shell structure (Cr2O3@C). The explosive reaction of chromocene with ammonium persulfate in an autoclave at 200∘C is crucial for the formation of this nanostructure. The Cr2O3 nanocrystals have a diameter of 5 to 20nm, which are entirely encapsulated by the amorphous carbon shell. The Cr2O3@C anode can retain a stable reversible capacity of 397mAhg-1 after 50 cycles at a current density of 119mA g-1.

A highly sensitive and selective electrochemical sensor for determination of Cr(VI) in the presence of Cr(III) using modified multi-walled carbon nanotubes/quercetin screen-printed electrode.

PubMed

Sadeghi, Susan; Garmroodi, Aziz

2013-12-01

A novel screen-printed carbon electrode modified with quercetin/multi-walled carbon nanotubes was fabricated for determination of Cr(VI) in the presence of excess of Cr(III) without any pretreatment. The method is based on accumulation of the quercetin-Cr(III) complex generated in situ from Cr(VI) at the modified electrode surface in an open circuit followed by differential pulse voltammetry detection. The new method allowed selective determination of Cr(VI) in the presence of Cr(III). The influence of various parameters affecting the adsorptive stripping voltammetry performance was investigated. Under the optimum conditions, the calibration plot was found to be linear in the Cr(VI) concentration range from 1.0 to 200 μmol(-1) with a limit of detection(S/N=3) of 0.3 μmol L(-1). The relative standard deviation (RSD%) of seven replicates of the current measurements for a 50 μmol(-1) of Cr(VI) solution was 3.0%. The developed electrode displayed a very low or no sensitivity to alkali, alkali-earth and transition metal cations and was successfully applied for the determination of Cr(VI) in drinking water samples. © 2013.

Highly Corrosion Resistant and Sandwich-like Si3N4/Cr-CrNx/Si3N4 Coatings Used for Solar Selective Absorbing Applications.

PubMed

Zhang, Ke; Du, Miao; Haoa, Lei; Meng, Jianping; Wang, Jining; Mi, Jing; Liu, Xiaopeng

2016-12-14

Highly corrosion resistant, layer-by-layer nanostructured Si 3 N 4 /Cr-CrN x /Si 3 N 4 coatings were deposited on aluminum substrate by DC/RF magnetron sputtering. Corrosion resistance experiments were performed in 0.5, 1.0, 3.0, and 5.0 wt % NaCl salt spray at 35 °C for 168 h. Properties of the coatings were comprehensively investigated in terms of optical property, surface morphology, microstructure, elemental valence state, element distribution, and potentiodynamic polarization. UV-vis-near-IR spectrophotometer and FTIR measurements show that the change process in optical properties of Si 3 N 4 /Cr-CrN x /Si 3 N 4 /Al coatings can be divided into three stages: a rapid active degradation stage, a steady passivation stage, and a transpassivation degradation stage. With the increase in the concentration of NaCl salt spray, solar absorptance and thermal emittance experienced a slight degradation. SEM images reveal that there is an increase in surface defects, such as microcracks and holes and -cracks. XRD and TEM measurements indicate that the phase structure changed partially and the content of CrO x and Al 2 O 3 has increased. Auger electron spectroscopy shows that the elements of Cr, N, and O have undergone a minor diffusion. Electrochemical polarization curves show that the as-deposited Si 3 N 4 /Cr-CrN x /Si 3 N 4 /Al coatings have excellent corrosion resistance of 3633.858 kΩ, while after corroding in 5.0 wt % NaCl salt spray for 168 h the corrosion resistance dropped to 13.759 kΩ. However, these coatings still have an outstanding performance of high solar absorptance of 0.924 and low thermal emittance of 0.090 after corroding in 3.0 wt % NaCl salt spray for 120 h. Thus, the Si 3 N 4 /Cr-CrN x /Si 3 N 4 /Al coating is a good choice for solar absorber coatings applied in the high-saline environment.

Microstructure, mechanical and tribological characterization of CrN/DLC/Cr-DLC multilayer coating with improved adhesive wear resistance

NASA Astrophysics Data System (ADS)

Sui, Xudong; Liu, Jinyu; Zhang, Shuaituo; Yang, Jun; Hao, Junying

2018-05-01

Adhesive wear is one of the major reasons for the failure of components during various tribological application, especially for rubbing with viscous materials. This study presents CrN/DLC/Cr-DLC multilayer composite coatings prepared on a plasma enhanced chemical vapor deposition (PECVD) device with the close field unbalanced magnetron sputtering ion plating (CFUBMSIP) technique. SEM, XRD and Raman spectroscopy were used to determine the structure of multilayer coatings. It was found that the multilayer coatings are composed by the alternating CrN and DLC layers. Compared with the single CrN coatings, the friction coefficient of the CrN/DLC/Cr-DLC multilayer coating decreases about more than seven times after sliding a distance of 500 m. This helps to reduce the adhesive wear of multilayer coatings. Compared with the single CrN and DLC coating, the wear rate of the CrN/DLC/Cr-DLC multilayer coating is reduced by an order of magnitude to 7.10 × 10-17 (sliding with AISI 440C) and 2.64 × 10-17 (sliding with TC4) m3/(N m). The improved tribological performance of multilayer coatings mainly attributes to the introduction of lubricant DLC and hard support CrN layers, the enhancement of crack propagation inhibition, and the increment of elastic recovery value We (71.49%) by multilayer design method.

Nb2O5 nanowires in-situ grown on carbon fiber: A high-efficiency material for the photocatalytic reduction of Cr(VI).

PubMed

Du, Yucheng; Zhang, Shihao; Wang, Jinshu; Wu, Junshu; Dai, Hongxing

2018-04-01

Niobium oxide nanowire-deposited carbon fiber (CF) samples were prepared using a hydrothermal method with amorphous Nb 2 O 5 ·nH 2 O as precursor. The physical properties of the samples were characterized by means of numerous techniques, including X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), UV-visible spectroscopy (UV-vis), N 2 adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy. The efficiency for the removal of Cr(VI) was determined. Parameters such as pH value and initial Cr(VI) concentration could influence the Cr(VI) removal efficiency or adsorption capacity of the Nb 2 O 5 /carbon fiber sample obtained after hydrothermal treatment at 160°C for 14hr. The maximal Cr(VI) adsorption capacity of the Nb 2 O 5 nanowire/CF sample was 115mg/g. This Nb 2 O 5 /CF sample also showed excellent photocatalytic activity and stability for the reduction of Cr(VI) under UV-light irradiation: the Cr(VI) removal efficiency reached 99.9% after UV-light irradiation for 1hr and there was no significant decrease in photocatalytic performance after the use of the sample for 10 repeated cycles. Such excellent Cr(VI) adsorption capacity and photocatalytic performance was related to its high surface area, abundant surface hydroxyl groups, and good UV-light absorption ability. Copyright © 2017. Published by Elsevier B.V.

Improving guideline concordance in multidisciplinary teams: preliminary results of a cluster-randomized trial evaluating the effect of a web-based audit and feedback intervention with outreach visits

PubMed Central

van Engen-Verheul, Mariëtte M.; Gude, Wouter T.; van der Veer, Sabine N.; Kemps, Hareld M.C.; Jaspers, Monique M.W.; de Keizer, Nicolette F.; Peek, Niels

2015-01-01

Despite their widespread use, audit and feedback (A&F) interventions show variable effectiveness on improving professional performance. Based on known facilitators of successful A&F interventions, we developed a web-based A&F intervention with indicator-based performance feedback, benchmark information, action planning and outreach visits. The goal of the intervention was to engage with multidisciplinary teams to overcome barriers to guideline concordance and to improve overall team performance in the field of cardiac rehabilitation (CR). To assess its effectiveness we conducted a cluster-randomized trial in 18 CR clinics (14,847 patients) already working with computerized decision support (CDS). Our preliminary results showed no increase in concordance with guideline recommendations regarding prescription of CR therapies. Future analyses will investigate whether our intervention did improve team performance on other quality indicators. PMID:26958310

Highly enhanced adsorption of Congo red by functionalized finger-citron-leaf-based porous carbon.

PubMed

Zhao, Gui-Hua; Fang, Yao-Yao; Dai, Wei; Ma, Na

2018-01-01

A novel high-performance porous carbon material, lanthanum(III)-doped finger-citron-leaf-based porous carbon (La/FPC), has been synthesized and used as an adsorbent for anion dye Congo red (CR). The La/FPC was characterized by nitrogen adsorption and desorption isotherms, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The adsorption performance of CR by the FPC and La/FPC composites with different contents of lanthanum(III) were evaluated in fixed-bed breakthrough experiments and batch tests at room temperature (298 K). The La/FPC had a high CR uptake capacity, which was superior to those previously reported for other adsorbents. The La/FPC sorbents can be easily regenerated using an ethanol elution technique, and after five cycles the reused La/FPC maintained about 98% of its original CR adsorption capacity. The adsorption kinetics of CR onto the lanthanum(III)-doped FPCs followed a pseudo-second-order kinetic model and fitted well with a Langmuir adsorption isotherm. La/FPC is a promising adsorbent for the removal of the anionic dyes from wastewater.

Oxidation resistant porous material for transpiration cooled vanes

NASA Technical Reports Server (NTRS)

Madsen, P.; Rusnak, R. M.

1972-01-01

Porous metal sheet with controlled permeability was made by space winding and diffusion bonding fine wire. Two iron-chromium-aluminum alloys and three-chromium alloys were used: GE 1541 (Fe-Cr-Al-Y), H 875 (Fe-Cr-Al-Si), TD Ni Cr, DH 245 (Ni-Cr-Al-Si) and DH 242 (Ni-Cr-Si-Cb). GE 1541 and H 875 were shown in initial tests to have greater oxidation resistance than the other candidate alloys and were therefore tested more extensively. These two materials were cyclic furnace oxidation tested in air at 1800 and 2000 F for accumulated exposure times of 4, 16, 64, 100, 200, 300, 400, 500, and and 600 hours. Oxidation weight gain, permeability change and mechanical properties were determined after exposure. Metallographic examination was performed to determine effects of exposure on the porous metal and electron beam weld joints of porous sheet to IN 100 strut material. Hundred hour stress rupture life and tensile tests were performed at 1800 F. Both alloys had excellent oxidation resistance and retention of mechanical properties and appear suitable for use as transpiration cooling materials in high temperature gas turbine engines.

Bioaccumulation of chromium in aquatic macrophyte Borreria scabiosoides Cham. & Schltdl.

NASA Astrophysics Data System (ADS)

Mangabeira, P. A.; Mielke, M. S.; Arantes, I.; Dutruch, L.; Silva, D. da. C.; Barbier, F.; de Almeida, A.-A. F.; Oliveira, A. H.; Severo, M. I. G.; Labejof, L.; Rocha, D. C.; Rosa, T. S.; Santana, K. B.; Gavrilov, K. L.; Galle, P.; Levi-Setti, R.; Grenier-Loustalot, M. F.

2006-07-01

The capacity of Borreria scabiosoides Cham. & Schltdl. growing in hydroponics solutions to remove Cr (III) from water was evaluated. This macrophytes efficiently removed Cr from water at concentrations of 25 and 50 mg/l Cr -1. High resolution imaging secondary ion mass-spectrometry (HRI-SIMS) measurements were performed using scanning ion microprobe at the University of Chicago (UC-SIM). The inductively coupled plasma sector type mass spectrometer (HR-ICP-MS) was used to analyse all samples. In general, plant roots exhibited higher metal concentrations than the aerial plants parts. Borreria shows promise for the removal and store Cr from contaminated wastewater. The ion images demonstrated that Cr is preferentially accumulated in cell walls and in some vacuoles of cortical roots cells. The number of Cr deposits are higher in cortical parenchyma, particularly in vacuoles and cell walls, compared to stellar tissue.

Reduction of hexavalent chromium with colloidal and supported palladium nanocatalysts

NASA Astrophysics Data System (ADS)

Tu, Weixia; Li, Kunjing; Shu, Xiaohui; Yu, William W.

2013-04-01

The Cr(VI) pollutants are known to cause serious harm to the environment and human health. Chemical reduction is one of the efficient methods to eliminate the Cr(VI) pollutants. We synthesized polyvinylpyrrolidone-stabilized palladium (PVP-Pd) colloidal nanoparticles to catalytically reduce Cr(VI). The PVP-Pd colloidal nanocatalysts were active on the complete reduction of Cr(VI) to Cr(III) with a rate of 22.2 molCr/(molPd min) or a turn-over frequency (TOF) of 1,329 h-1 at pH 4.0 and 45 °C. Magnetic Fe3O4 support was used for recycling the palladium nanocatalysts. The as-prepared Pd-Fe3O4 catalyst was easy to be separated from the reaction system by simply applying an external magnet and it exhibited efficient and stable reduction performance even after eight recycles.

First principles calculations of electronic structure and magnetic properties of Cr-based magnetic semiconductors Al{sub 1-x}Cr{sub x}X (X=N, P, As, Sb)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saeed, Y., E-mail: yasir_saeed54321@yahoo.co; Shaukat, A., E-mail: schaukat@gmail.co; Nazir, S., E-mail: nazirsafdar@gmail.co

2010-01-15

First principles calculations based on the density functional theory (DFT) within the local spin density approximation are performed to investigate the electronic structure and magnetic properties of Cr-based zinc blende diluted magnetic semiconductors Al{sub 1-x}Cr{sub x}X (X=N, P, As, Sb) for 0<=x<=0.50.The behaviour of magnetic moment of Al{sub 1-x}Cr{sub x}X at each Cr site as well as the change in the band gap value due to spin down electrons has been studied by increasing the concentration of Cr atom and through changing X from N to Sb. Furthermore, the role of p-d hybridization is analyzed in the electronic band structuremore » and exchange splitting of d-dominated bands. The interaction strength is stronger in Al{sub 1-x}Cr{sub x}N and becomes weaker in Al{sub 1-x}Cr{sub x}Sb. The band gap due to the spin down electrons decreases with the increased concentration of Cr in Al{sub 1-x}Cr{sub x}X, and as one moves down along the isoelectronic series in the group V from N to Sb. Our calculations also verify the half-metallic ferromagnetic character in Cr doped AlX. - Graphical abstract: The prototype structures of Cr doped AlX (X=N, P, As, Sb) compounds: (A) zinc blende AlP for x=0, (B) Cr{sub 1}Al{sub 7}P{sub 8} for x=0.125, (C) Cr{sub 1}Al{sub 3}P{sub 4} for x=0.25, (D) Cr{sub 1}Al{sub 1}P{sub 2} for x=0.5.« less

Precursor preparation for Ca-Al layered double hydroxide to remove hexavalent chromium coexisting with calcium and magnesium chlorides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhong, Lihua; He, Xiaoman; Qu, Jun

Al(OH){sub 3} and Ca(OH){sub 2} powders are co-ground to prepare a precursor which hydrates into a layered double hydroxide (LDH) phase by agitation in aqueous solution with target hexavalent chromium (Cr(VI)) at room temperature, to achieve an obvious improvement in removal efficiency of Cr(VI) through an easy incorporation into the structure. Although the prepared precursor transforms into LDH phases also when agitated in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist. The adsorption isotherm and kinetic studies show that the phenomena occurring on the Al-Ca precursor fit a pseudo-second-order kineticsmore » with a Langmuir adsorption capacity of 59.45 mg/g. Besides, characterizations of the prepared precursor and the samples after adsorption are also performed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Transmission electron microscope (TEM) to understand the reason of the preferential incorporation of Cr(VI) to the coexisting chloride salts during the LDH phase formation. - Graphical abstract: Activated Ca-Al hydroxides (C{sub 3}A) transformed into Ca-Al-OH compound when agitated in water. Ca-Al precursor (C{sub 3}A) was agitated in a hexavalent chromium (Cr(VI)) solution to form Al-Ca-CrO{sub 4} LDH product. Ca-Al-CrO{sub 4} LDH phase occurred preferentially to Ca-Al-MCl{sub 2} LDH phases in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist. - Highlights: • Activated Ca-Al hydroxides transformed into LDH when agitated in water with some inorganic substances. • Hexavalent Cr was incorporated in the LDH structure at high adsorption capacity. • Ca-Al-Cr LDH phase occurred preferentially to Ca-Al-MCl{sub 2} LDH phases with coexistence. • The prepared Ca-Al hydroxides had high performance as adsorbent even with high salinity of the solution.« less

[Simultaneous determination of guanidinoacetate, creatine and creatinine by liquid chromatography-tandem mass spectrometry: a diagnostic tool for creatine deficiency syndromes in body fluids and a perspective use on cultured fibroblasts].

PubMed

Van Noolen, Laetitia; Monneret, Denis; Ducros, Véronique; Corne, Christelle; Lunardi, Joël; Faure, Patrice

2013-01-01

Guanidinoacetate (GAA) and creatine (Cr) are creatine deficiency syndromes (CDS) biochemical markers. We describe a liquid chromatography - tandem mass spectrometry method (LC/MSMS) performing simultaneous analysis of GAA, Cr and creatinine (Crn). Study of Cr uptake by fibroblasts for Cr transporter defect diagnosis is also assessed. The three butylated compounds were separated by liquid chromatography and MSMS quantification was achieved by isotopic dilution with electrospray positive ion mode. Linearity was demonstrated from 0 to 600, 675 and 4500 μmol/L and limit of quantification was 0.1, 0.04 and 0.9 μmol/L for GAA, Cr, and Crn respectively. Intra- and inter-assay precision for each analyte was better than 11%, and standard recoveries ranged from 83 to 109%. Reference values in cerebrospinal fluid samples for subjects ≥14 years were also established for GAA and Cr. Five fibroblast cell lines were used for Cr uptake study. Cr uptake by fibroblasts increased with the Cr media concentrations and was significantly inhibited by 3-guanidinopropionate (500 μmol/L), a Cr transporter inhibitor (96h incubation, [Cr media] = 25 μmol/L, p<0.05). A reliable LC/MSMS method for the diagnosis of CDS was developed in different biological fluids. Finally, results of the Cr uptake study reinforce the interest of this technique to diagnose Cr transporter deficiencies.

A High Sensitivity Isopropanol Vapor Sensor Based on Cr₂O₃-SnO₂ Heterojunction Nanocomposites via Chemical Precipitation Route.

PubMed

Jawaher, K Rackesh; Indirajith, R; Krishnan, S; Robert, R; Pasha, S K Khadheer; Deshmukh, Kalim; Sastikumar, D; Das, S Jerome

2018-08-01

Cr2O3-SnO2 heterojunction nanocomposites were prepared via chemical precipitation method. The prepared samples were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectra and Field Emission Electron Microscopy (FESEM). The XRD spectrum confirms the presence of both tetragonal rutile SnO2 and rhombohedral corundum Cr2O3 structure. Further investigation into the gas sensing performances of the prepared Cr2O3-SnO2 nanocomposites exhibited an enhanced sensitivity towards VOPs such as isopropanol, acetone, ethanol and formaldehyde. Especially, isopropanol vapor sensor shows excellent sensitivity at an operating temperature of 100 °C. The highest sensitivity for Cr2O3-SnO2 heterojunction nanocomposites indicate that these materials can be a good candidate for the production of high-performance isopropanol sensors.

Stratification of welding fumes and grinding particles in a large factory hall equipped with displacement ventilation.

PubMed

Niemelä, R; Koskela, H; Engström, K

2001-08-01

The purpose of the study was to investigate the performance of displacement ventilation in a large factory hall where large components of stainless steel for paper, pulp and chemical industries were manufactured. The performance of displacement ventilation was evaluated in terms of concentration distributions of welding fumes and grinding particles, flow field of the supply air and temperature distributions. Large differences in vertical stratification patterns between hexavalent chromium (Cr(VI)) and other particulate contaminants were observed. The concentration of Cr(VI) was notably lower in the zone of occupancy than in the upper part of the factory hall, whereas the concentrations of total airborne particles and trivalent chromium (Cr(III)) were higher in the occupied zone than in the upper zone. The stratification of Cr(VI) had the same tendency as the air temperature stratification caused by the displacement flow field.

Do Cartilage Repair Procedures Prevent Degenerative Meniscus Changes? Longitudinal T1ρ and Morphological Evaluation at 3.0T

PubMed Central

Jungmann, Pia M.; Li, Xiaojuan; Nardo, Lorenzo; Subburaj, Karupppasamy; Lin, Wilson; Ma, C. Benjamin; Majumdar, Sharmila; Link, Thomas M.

2014-01-01

Background Cartilage repair (CR) procedures are widely accepted for treatment of isolated cartilage defects at the knee joint. However, it is not well known whether these procedures prevent degenerative joint disease. Hypothesis/Purpose CR procedures prevent accelerated qualitative and quantitative progression of meniscus degeneration in individuals with focal cartilage defects. Study Design Cohort Study; Level of evidence 2b Methods A total of 94 subjects were studied. CR procedures were performed on 34 patients (n=16 osteochondral transplantation, n=18 microfracture); 34 controls were matched. An additional 13 patients received CR and anterior cruciate ligament (ACL) reconstruction (CR&ACL) and 13 patients received only ACL reconstruction. 3.0T MRI with T1ρ mapping and sagittal fat-saturated intermediate-weighted fast spin echo (FSE) sequences was performed to analyze menisci quantitatively and qualitatively (Whole-Organ Magnetic Resonance Imaging Score, WORMS). CR and CR&ACL patients were examined 4 months (n=34; n=13), 1 (n=21; n=8) and 2 (n=9; n=5) years post CR. Control subjects were scanned at baseline and after 1 and 2 years, ACL patients after 1 and 2 years. Results At baseline, global meniscus T1ρ values were higher in individuals with CR (14.2±0.6ms; P=0.004) and in individuals with CR&ACL (17.1±0.9ms; P<0.001) when compared to controls (12.8±0.6ms). After two years, there was a statistical difference between T1ρ at the overlying meniscus above cartilage defects (16.4±1.0ms) and T1ρ of the subgroup of control knees without cartilage defects (12.1±0.8ms; P<0.001) and a statistical trend to the CR group (13.3±1.0 ms; P=0.088). At baseline, 35% of subjects with CR showed morphological meniscus tears at the overlying meniscus; 10% of CR subjects showed an increase of WORMS meniscus score within the first year, none progressed in the second year. Control subjects with (without) cartilage defects showed meniscus tears in 30% (5%) at baseline; 38% (19%) increased within the first, and 15% (10%) within the second year. Conclusions This study identified more severe meniscus degeneration after CR surgery compared to controls. However, progression of T1ρ values was not observed from 1 to 2 years after surgery. These results suggest, that CR may prevent degenerative meniscus changes. PMID:23104606

Enhanced performance of Cr,Yb:YAG microchip laser by bonding Yb:YAG crystal.

PubMed

Cheng, Ying; Dong, Jun; Ren, Yingying

2012-10-22

Highly efficient, laser-diode pumped Yb:YAG/Cr,Yb:YAG self-Q-switched microchip lasers by bonding Yb:YAG crystal have been demonstrated for the first time to our best knowledge. The effect of transmission of output coupler (T(oc)) on the enhanced performance of Yb:YAG/Cr,Yb:YAG microchip lasers has been investigated and found that the best laser performance was achieved with T(oc) = 50%. Slope efficiency of over 38% was achieved. Average output power of 0.8 W was obtained at absorbed pump power of 2.5 W; corresponding optical-to-optical efficiency of 32% was obtained. Laser pulses with pulse width of 1.68 ns, pulse energy of 12.4 μJ, and peak power of 7.4 kW were obtained. The lasers oscillated in multi-longitudinal modes. The wide separation of longitudinal modes was attributed to the mode selection by combined etalon effect of Cr,Yb:YAG, Yb:YAG thin plates and output coupler. Stable periodical pulse trains at different pump power levels have been observed owing to the longitudinal modes coupling and competition.

Versatile Oxide Films Protect FeCrAl Alloys Under Normal Operation and Accident Conditions in Light Water Power Reactors

NASA Astrophysics Data System (ADS)

Rebak, Raul B.

2018-02-01

The US has currently a fleet of 99 nuclear power light water reactors which generate approximately 20% of the electricity consumed in the country. Near 90% of the reactors are at least 30 years old. There are incentives to make the existing reactors safer by using accident tolerant fuels (ATF). Compared to the standard UO2-zirconium-based system, ATF need to tolerate loss of active cooling in the core for a considerably longer time while maintaining or improving the fuel performance during normal operation conditions. Ferritic iron-chromium-aluminum (FeCrAl) alloys have been identified as an alternative to replace current zirconium alloys. They contain Fe (base) + 10-22 Cr + 4-6 Al and may contain smaller amounts of other elements such as molybdenum and traces of others. FeCrAl alloys offer outstanding resistance to attack by superheated steam by developing an alumina oxide on the surface in case of a loss of coolant accident like at Fukushima. FeCrAl alloys also perform well under normal operation conditions both in boiling water reactors and pressurized water reactors because they are protected by a thin oxide rich in chromium. Under normal operation condition, the key element is Cr and under accident conditions it is Al.

A novel route for electrosynthesis of CuCr(2)O(4) nanocomposite with p-type conductive polymer as a high performance material for electrochemical supercapacitors.

PubMed

Shayeh, Javad Shabani; Sadeghinia, Mohammad; Siadat, Seyed Omid Ranaei; Ehsani, Ali; Rezaei, Mehran; Omidi, Meisam

2017-06-15

In this work, supercapacitive performance of polypyrrole copper chromate nano particles (Ppy/CuCr 2 O 4 NPs) was studied. CuCr 2 O 4 NPs with the average size of 20nm were synthesized simply by hydrothermal method and the composite electrodes were then electropolymerized on the surface of glassy carbon electrode. Common surface analysis techniques such as scanning electron microscopy (SEM), transmission electron microscopy(TEM) and Fourier transform infrared (FTIR) were used to study the morphology and structure of the composite. Furthermore, for electrochemical evaluation of composite electrodes, techniques including cyclic voltammetry (CV), galvanostatic charge discharge (CD) and impedance spectroscopy (EIS) were used. Using cyclic voltammetry, the specific capacitance values of Ppy and Ppy/CuCr 2 O 4 NPs were calculated to be 109 and 508 F g -1 , respectively. Results show that using CuCr 2 O 4 NPs in the structure of polymeric films led to increased specific capacitance of composite electrodes more than four times that of poly pyrrole. Increasing the conductivity and stability of composite electrodes through continuous cycles are the other advantages of using CuCr 2 O 4 NPs as active materials in a polymeric structure. Copyright © 2017 Elsevier Inc. All rights reserved.

Biomarkers of oxidative stress in electroplating workers exposed to hexavalent chromium.

PubMed

Pan, Chih-Hong; Jeng, Hueiwang Anna; Lai, Ching-Huang

2018-01-01

This study evaluates levels of biomarkers of oxidative DNA damage and lipid peroxidation in 105 male workers at 16 electroplating companies who had been exposed to hexavalent chromium (Cr(VI)). The study participants were 230 non-smoking male workers, comprising 105 electroplating workers who had been exposed to chromium and 125 control subjects who performed office tasks. Personal air samples, spot urine samples, hair samples, fingernail samples and questionnaires were used to quantify exposure to Cr(VI), oxidative DNA damage, lipid peroxidation, and environmental pollutants. Both the geometric mean personal concentrations of Cr(VI) of the Cr-exposed workers and the total Cr concentrations in the air to which they were exposed significantly exceeded those for the control subjects. The geometric mean concentrations of Cr in urine, hair and fingernails, and the urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG), and malondialdehyde (MDA) levels in the Cr(VI) exposed workers exceeded those in the control subjects. Daily cumulative Cr(VI) exposure and urinary Cr were significantly correlated with urinary 8-OHdG levels following adjustments for covariates. A ten-fold increase in urinary Cr level was associated with a 1.73-fold increase in urinary 8-OHdG level. Daily cumulative Cr(VI) exposure and urinary Cr level were significantly correlated with urinary MDA level following adjustments for covariates. A ten-fold increase in urinary Cr was associated with a 1.45-fold increase in urinary MDA. Exposure to Cr(VI) increased oxidative DNA injury and the oxidative deterioration of lipids in electroplating workers.

Development and Validation of Accident Models for FeCrAl Cladding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gamble, Kyle Allan Lawrence; Hales, Jason Dean

2016-08-01

The purpose of this milestone report is to present the work completed in regards to material model development for FeCrAl cladding and highlight the results of applying these models to Loss of Coolant Accidents (LOCA) and Station Blackouts (SBO). With the limited experimental data available (essentially only the data used to create the models) true validation is not possible. In the absence of another alternative, qualitative comparisons during postulated accident scenarios between FeCrAl and Zircaloy-4 cladded rods have been completed demonstrating the superior performance of FeCrAl.

Advanced experimental study on giant magnetoresistance of Fe/Cr superlattices by rf-sputtering

NASA Astrophysics Data System (ADS)

Obi, Y.; Takanashi, K.; Mitani, Y.; Tsuda, N.; Fujimori, H.

1992-02-01

The study on MagnetoResistance (MR) has been performed for the Fe/Cr SuperLattice (SL) produced by the rf-sputtering method. Especially the effect of the preparation condition on MR has been investigated in detail. The MR oscillates with respect to the Cr layer thickness ( tCr) as was reported by Parkin et al. [1]. The characteristic experimental results is that the MR depends strongly on the Ar pressure. This indicates that the size of the MR is greatly affected by the interface roughness of the SL induced by the different Ar pressure during sputtering.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prates, P. B.; Maliska, A. M.; Ferreira, A. S.

A thermodynamic analysis of the Cr-Ge system suggested that it was possible to produce a nanostructured Cr{sub 3}Ge phase by mechanical alloying. The same analysis showed that, due to low activation energies, Cr-poor crystalline and/or amorphous alloy could also be formed. In fact, when the experiment was performed, Cr{sub 11}Ge{sub 19} and amorphous phases were present for small milling times. For milling times larger than 15 h these additional phases decomposed and only the nanostructured Cr{sub 3}Ge phase remained up to the highest milling time used (32 h). From the differential scanning calorimetry measurements, the Avrami exponent n was obtained, indicating thatmore » the nucleation and growth of the nanostructured Cr{sub 3}Ge phase may be restricted to one or two dimensions, where the Cr and Ge atoms diffuse along the surface and grain boundaries. In addition, contributions from three-dimensional diffusion with a constant nucleation rate may be present. The thermal diffusivity of the nanostructured Cr{sub 3}Ge phase was determined by photoacoustic absorption spectroscopy measurements.« less

Scratch Testing of Hot-Pressed Monolithic Chromium Diboride (CrB2) and CrB2 + MoSi2 Composite

NASA Astrophysics Data System (ADS)

Bhatt, B.; Murthy, T. S. R. Ch.; Singh, K.; Sashanka, A.; Vishwanadh, B.; Sonber, J. K.; Sairam, K.; Nageswara Rao, G. V. S.; Srinivasa Rao, T.; Kain, Vivekanand

2017-10-01

The tribological performance of hot-pressed monolithic CrB2 and a newly developed CrB2 + 20 vol.% MoSi2 composite was investigated by using scratch test. The test was carried out under progressive loading ranging from 0.9 to 30 N over a scratch distance of 3 mm. In situ values of coefficient of friction (COF), depth of penetration and acoustic emission were recorded. The wear volume and fracture toughness were also calculated. COF of both materials is increased with increasing the scratch length and progressive load. COF of the composite was observed to be slightly higher compared to the monolithic CrB2. The wear volume of the composite is 60% higher compared to monolithic CrB2. Fracture toughness values of 2.48 and 2.81 MPa m1/2 were calculated for monolithic CrB2 and CrB2 + 20 vol.% MoSi2 composite, respectively. Microstructural characterization indicates that the abrasive wear is the dominant wear mechanism in both the materials.

Clinical comparison of CR and screen film for imaging the critically ill neonate

NASA Astrophysics Data System (ADS)

Andriole, Katherine P.; Brasch, Robert C.; Gooding, Charles A.; Gould, Robert G.; Cohen, Pierre A.; Rencken, Ingo R.; Huang, H. K.

1996-05-01

A clinical comparison of computed radiography (CR) versus screen-film for imaging the critically-ill neonate is performed, utilizing a modified (hybrid) film cassette containing a CR (standard ST-V) imaging plate, a conventional screen and film, allowing simultaneous acquisition of perfectly matched CR and plain film images. For 100 portable neonatal chest and abdominal projection radiographs, plain film was subjectively compared to CR hardcopy. Three pediatric radiologists graded overall image quality on a scale of one (poor) to five (excellent), as well as visualization of various anatomic structures (i.e., lung parenchyma, pulmonary vasculature, tubes/lines) and pathological findings (i.e., pulmonary interstitial emphysema, pleural effusion, pneumothorax). Results analyzed using a combined kappa statistic of the differences between scores from each matched set, combined over the three readers showed no statistically significant difference in overall image quality between screen- film and CR (p equals 0.19). Similarly, no statistically significant difference was seen between screen-film and CR for anatomic structure visualization and for visualization of pathological findings. These results indicate that the image quality of CR is comparable to plain film, and that CR may be a suitable alternative to screen-film imaging for portable neonatal chest and abdominal examinations.

Luminescent properties of Cr-doped (GdX, Y1-X)3Al5O12 infra-red scintillator crystals

NASA Astrophysics Data System (ADS)

Suzuki, Akira; Kurosawa, Shunsuke; Yamaji, Akihiro; Shoji, Yasuhiro; Pejchal, Jan; Kamada, Kei; Yokota, Yuui; Yoshikawa, Akira

2014-10-01

Cr-doped (GdX Y1-X)3Al5O12 (X = 0, 0.25, 0.50) crystals prepared by the micro-pulling down method were investigated to develop a infra-red scintillator for implantable patient dosimeter in radiation therapy. In order to evaluate their optical and scintillation performance, the following properties were measured: (i) transmittance between ultra-violet and near-infra red region, (ii) photoluminescence spectra under Xe-lamp excitation, and (iii) X-ray excited radio-luminescence spectra. Cr:Y3Al5O12 and Cr:(Gd0.25 Y0.75)3Al5O12 crystals showed increased transmittance of 80%, while Cr:(Gd0.50 Y0.50)3Al5O12 had a lower transmittance of 40% due to its polycrystalline structure. In addition, all the Cr:(GdX Y1-X)3Al5O12 crystals showed sharp scintillation luminescence peaks ascribed to Cr3+ d-d transitions. Therefore, these results suggested that Cr:Y3Al5O12 and Cr:(Gd0.25 Y0.75)3Al5O12 crystals can be candidate materials for the dosimeter use.

The Effect and Safety of Short-Term Creatine Supplementation on Performance of Push-Ups

DTIC Science & Technology

2007-03-01

MILITARY MEDICI’lE. 172. 3:312. 2007 The Effect and Safety of Short-Term Creatine Supplementation on Performance of Push-Ups Guarantor: LT Matthew...effects of short-term oral creatine (Cr) supplementation on exercise performance and on blood pressure and renal function were assessed. Thirty-five...before to after supplementation (p 0.437; power 0.98). The Cr group demonstrated a sig- nificant increase in serum creatinine levels (p 0.001), com

Structural, optical, and thermal properties of MAX-phase Cr2AlB2

NASA Astrophysics Data System (ADS)

Li, Xiao-Hong; Cui, Hong-Ling; Zhang, Rui-Zhou

2018-04-01

First-principles calculations of the structural, optical, and thermal properties of Cr2AlB2 are performed using the pseudopotential plane-wave method within the generalized gradient approximation (GGA). Calculation of the elastic constant and phonon dispersion indicates that Cr2AlB2 is mechanically and thermodynamically stable. Analysis of the band structure and density of states indicates that Cr2AlB2 is metallic. The thermal properties under increasing temperature and pressure are investigated using the quasi-harmonic Debye model. The results show that anharmonic effects on Cr2AlB2 are important at low temperature and high pressure. The calculated equilibrium primitive cell volume is 95.91 Å3 at T = 300 K, P = 0 GPa. The ability of Cr2AlB2 to resist volume changes becomes weaker with increasing temperature and stronger with increasing pressure. Analysis of optical properties of Cr2AlB2 shows that the static dielectric function of Cr2AlB2 is 53.1, and the refractive index n 0 is 7.3. If the incident light has a frequency exceeding 16.09 eV, which is the plasma frequency of Cr2AlB2, Cr2AlB2 changes from metallic to dielectric material.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Briggs, Samuel A.; Edmondson, Philip D.; Littrell, Kenneth C.

Here, FeCrAl alloys are currently under consideration for accident-tolerant fuel cladding applications in light water reactors owing to their superior high-temperature oxidation and corrosion resistance compared to the Zr-based alloys currently employed. However, their performance could be limited by precipitation of a Cr-rich α' phase that tends to embrittle high-Cr ferritic Fe-based alloys. In this study, four FeCrAl model alloys with 10–18 at.% Cr and 5.8–9.3 at.% Al were neutron-irradiated to nominal damage doses up to 7.0 displacements per atom at a target temperature of 320 °C. Small angle neutron scattering techniques were coupled with atom probe tomography to assessmore » the composition and morphology of the resulting α' precipitates. It was demonstrated that Al additions partially destabilize the α' phase, generally resulting in precipitates with lower Cr contents when compared with binary Fe-Cr systems. The precipitate morphology evolution with dose exhibited a transient coarsening regime akin to previously observed behavior in aged Fe-Cr alloys. Similar behavior to predictions of the LSW/UOKV models suggests that α' precipitation in irradiated FeCrAl is a diffusion-limited process with coarsening mechanisms similar to those in thermally aged high-Cr ferritic alloys.« less

Investigation of equilibrium and kinetics of Cr(VI) adsorption by dried Bacillus cereus using response surface methodology.

PubMed

Yang, Kai; Zhang, Jing; Yang, Tao; Wang, Hongyu

2016-01-01

In this study, response surface methodology (RSM) based on three-variable-five-level central composite rotatable design was used to analyze the effects of combined and individual operating parameters (biomass dose, initial concentration of Cr(VI) and pH) on the Cr(VI) adsorption capacity of dried Bacillus cereus. A quadratic polynomial equation was obtained to predict the adsorbed Cr(VI) amount. Analysis of variance showed that the effect of biomass dose was the key factor in the removal of Cr(VI). The maximum adsorbed Cr(VI) amount (30.93 mg g(-1)) was found at 165.30 mg L(-1), 2.96, and 3.01 g L(-1) for initial Cr(VI) concentration, pH, and biosorbent dosage, respectively. The surface chemical functional groups and microstructure of unloaded and Cr(VI)-loaded dried Bacillus cereus were identified by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), respectively. Besides, the results gained from these studies indicated that Langmuir isotherm and the second-order rate expression were suitable for the removal of Cr(VI) from wastewater. The results revealed RSM was an effective method for optimizing biosorption process, and dried Bacillus cereus had a remarkable performance on the removal of Cr(VI) from wastewater.

Ambient-temperature NO oxidation over amorphous CrOx-ZrO 2 mixed oxide catalysts: Significant promoting effect of ZrO 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Aiyong; Guo, Yanglong; Gao, Feng

2017-03-01

Three series of Cr-based mixed oxides (Cr-Co, Cr-Fe, and Cr-Ni oxides) with high specific surface areas and amorphous textures are synthesized using a novel sol-gel method. These mixed oxides, in comparison to their pure metal oxide (CrOx, Co3O4, FeOx and NiO) counterparts, display enhanced performance for catalytic oxidation of low-concentration NO at room temperature. Over best performing catalysts, 100% NO conversion can be maintained up to 30 h of operation at a high space velocity of 45,000 ml g-1 h-1. The amorphous structure is found to be critical for these catalysts to maintain high activity and durability. Cr/M (M=Co, Femore » and Ni) molar ratio, nitrate precursor decomposition temperature and catalyst calcination temperature are important criteria for the synthesis of the highly active catalysts. This work was supported by National Basic Research Program of China (2013CB933200), National Natural Science Foundation of China (21577035, 21577034), Commission of Science and Technology of Shanghai Municipality (15DZ1205305) and 111 Project (B08021). Aiyong Wang gratefully acknowledges the China Scholarship Council for the Joint-Training Scholarship Program with the Pacific Northwest National Laboratory (PNNL). PNNL is operated for the U.S. Department of Energy (DOE) by Battelle. FG and CHFP are supported by the U.S. DOE/Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office.« less

Evaluating the effect of a web-based quality improvement system with feedback and outreach visits on guideline concordance in the field of cardiac rehabilitation: rationale and study protocol.

PubMed

van Engen-Verheul, Mariëtte M; de Keizer, Nicolette F; van der Veer, Sabine N; Kemps, Hareld M C; Scholte op Reimer, Wilma J M; Jaspers, Monique W M; Peek, Niels

2014-12-31

Implementation of clinical practice guidelines into daily care is hampered by a variety of barriers related to professional knowledge and collaboration in teams and organizations. To improve guideline concordance by changing the clinical decision-making behavior of professionals, computerized decision support (CDS) has been shown to be one of the most effective instruments. However, to address barriers at the organizational level, additional interventions are needed. Continuous monitoring and systematic improvement of quality are increasingly used to achieve change at this level in complex health care systems. The study aims to assess the effectiveness of a web-based quality improvement (QI) system with indicator-based performance feedback and educational outreach visits to overcome organizational barriers for guideline concordance in multidisciplinary teams in the field of cardiac rehabilitation (CR). A multicenter cluster-randomized trial with a balanced incomplete block design will be conducted in 18 Dutch CR clinics using an electronic patient record with CDS at the point of care. The intervention consists of (i) periodic performance feedback on quality indicators for CR and (ii) educational outreach visits to support local multidisciplinary QI teams focussing on systematically improving the care they provide. The intervention is supported by a web-based system which provides an overview of the feedback and facilitates development and monitoring of local QI plans. The primary outcome will be concordance to national CR guidelines with respect to the CR needs assessment and therapy indication procedure. Secondary outcomes are changes in performance of CR clinics as measured by structure, process and outcome indicators, and changes in practice variation on these indicators. We will also conduct a qualitative process evaluation (concept-mapping methodology) to assess experiences from participating CR clinics and to gain insight into factors which influence the implementation of the intervention. To our knowledge, this will be the first study to evaluate the effect of providing performance feedback with a web-based system that incorporates underlying QI concepts. The results may contribute to improving CR in the Netherlands, increasing knowledge on facilitators of guideline implementation in multidisciplinary health care teams and identifying success factors of multifaceted feedback interventions. NTR3251.

Heterogeneous epoxide carbonylation by cooperative ion-pair catalysis in Co(CO) 4 –-incorporated Cr-MIL-101

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Hoyoung D.; Dinca, Mircea; Roman-Leshkov, Yuriy

Here, despite the commercial desirability of epoxide carbonylation to β-lactones, the reliance of this process on homogeneous catalysts makes its industrial application challenging. Here we report the preparation and use of a Co(CO) 4 –-incorporated Cr-MIL-101 (Co(CO) 4cCr-MIL-101, Cr-MIL-101 = Cr 3O(BDC) 3F, H2BDC = 1,4-benzenedicarboxylic acid) heterogeneous catalyst for the ring-expansion carbonylation of epoxides, whose activity, selectivity, and substrate scope are on par with those of the reported homogeneous catalysts. We ascribe the observed performance to the unique cooperativity between the postsynthetically introduced Co(CO) 4 – and the site-isolated Lewis acidic Cr(III) centers in the metal–organic framework (MOF). Themore » heterogeneous nature of Co(CO) 4cCr-MIL-101 allows the first demonstration of gas-phase continuous-flow production of β-lactones from epoxides, attesting to the potential applicability of the heterogeneous epoxide carbonylation strategy.« less

Heterogeneous epoxide carbonylation by cooperative ion-pair catalysis in Co(CO) 4 –-incorporated Cr-MIL-101

DOE PAGES

Park, Hoyoung D.; Dinca, Mircea; Roman-Leshkov, Yuriy

2017-03-21

Here, despite the commercial desirability of epoxide carbonylation to β-lactones, the reliance of this process on homogeneous catalysts makes its industrial application challenging. Here we report the preparation and use of a Co(CO) 4 –-incorporated Cr-MIL-101 (Co(CO) 4cCr-MIL-101, Cr-MIL-101 = Cr 3O(BDC) 3F, H2BDC = 1,4-benzenedicarboxylic acid) heterogeneous catalyst for the ring-expansion carbonylation of epoxides, whose activity, selectivity, and substrate scope are on par with those of the reported homogeneous catalysts. We ascribe the observed performance to the unique cooperativity between the postsynthetically introduced Co(CO) 4 – and the site-isolated Lewis acidic Cr(III) centers in the metal–organic framework (MOF). Themore » heterogeneous nature of Co(CO) 4cCr-MIL-101 allows the first demonstration of gas-phase continuous-flow production of β-lactones from epoxides, attesting to the potential applicability of the heterogeneous epoxide carbonylation strategy.« less

a Study on Microstructure Characteristics of IN SITU Formed TiC Reinforced Composite Coatings

NASA Astrophysics Data System (ADS)

Liu, Peng; Guo, Wei; Luo, Hui

2012-04-01

In situ synthesized TiC reinforced composite coating was fabricated by laser cladding of Al-Ni-Cr-C powders on titanium alloys, which can greatly improve the surface performance of the substrate. In this study, the Al-Ni-Cr-C laser-cladded composite coatings have been researched by means of X-ray diffraction, scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). There was a metallurgical combination between the Al-Ni-Cr-C laser-cladded coating and the Ti-6Al-4V substrate, and the micro-hardness of the Al-Ni-Cr-C laser-cladded coating was in the range of 1200-1450 HV0.2, which was 3-4 times higher than that of Ti-6Al-4V substrate. Furthermore, the reinforcement of theAl-Ni-Cr-C laser-cladded coating were mainly contributed to the action of the TiC, Ti3Al, Cr7C3, Al8Cr5 phases and the solution strengthening.

IMPROVED Cr II log(gf ) VALUES AND ABUNDANCE DETERMINATIONS IN THE PHOTOSPHERES OF THE SUN AND METAL-POOR STAR HD 84937

PubMed Central

Lawler, J. E.; Sneden, C.; Nave, G.; Den Hartog, E. A.; Emrahođlu, N.; Cowan, J. J.

2017-01-01

New emission branching fraction (BF) measurements for 183 lines of the second spectrum of chromium (Cr II) and new radiative lifetime measurements from laser-induced fluorescence for 8 levels of Cr+ are reported. The goals of this study are to improve transition probability measurements in Cr II and reconcile solar and stellar Cr abundance values based on Cr I and Cr II lines. Eighteen spectra from three Fourier Transform Spectrometers supplemented with ultraviolet spectra from a high-resolution echelle spectrometer are used in the BF measurements. Radiative lifetimes from this study and earlier publications are used to convert the BFs into absolute transition probabilities. These new laboratory data are applied to determine the Cr abundance log ε in the Sun and metal-poor star HD 84937. The mean result in the Sun is 〈logε (Cr II)〉 = 5.624±0.009 compared to 〈logε(Cr I)〉 = 5.644 ± 0.006 on a scale with the hydrogen abundance log ε(H) = 12 and with the uncertainty representing only line-to-line scatter. A Saha (ionization balance) test on the photosphere of HD 84937 is also performed, yielding 〈logε(Cr II)〉 = 3.417 ± 0.006 and 〈log ε(Cr I, lower level excitation potential E. P. >30 eV)〉 = 3.3743±30.011 for this dwarf star. We find a correlation of Cr with the iron-peak element Ti, suggesting an associated nucleosynthetic production. Four iron-peak elements (Cr along with Ti, V, and Sc) appear to have a similar (or correlated) production history—other iron-peak elements appear not to be associated with Cr. PMID:28579650

IMPROVED Cr II log(gf ) VALUES AND ABUNDANCE DETERMINATIONS IN THE PHOTOSPHERES OF THE SUN AND METAL-POOR STAR HD 84937.

PubMed

Lawler, J E; Sneden, C; Nave, G; Den Hartog, E A; Emrahođlu, N; Cowan, J J

2017-01-01

New emission branching fraction (BF) measurements for 183 lines of the second spectrum of chromium (Cr II) and new radiative lifetime measurements from laser-induced fluorescence for 8 levels of Cr + are reported. The goals of this study are to improve transition probability measurements in Cr II and reconcile solar and stellar Cr abundance values based on Cr I and Cr II lines. Eighteen spectra from three Fourier Transform Spectrometers supplemented with ultraviolet spectra from a high-resolution echelle spectrometer are used in the BF measurements. Radiative lifetimes from this study and earlier publications are used to convert the BFs into absolute transition probabilities. These new laboratory data are applied to determine the Cr abundance log ε in the Sun and metal-poor star HD 84937. The mean result in the Sun is 〈log ε (Cr II)〉 = 5.624±0.009 compared to 〈log ε (Cr I)〉 = 5.644 ± 0.006 on a scale with the hydrogen abundance log ε (H) = 12 and with the uncertainty representing only line-to-line scatter. A Saha (ionization balance) test on the photosphere of HD 84937 is also performed, yielding 〈log ε (Cr II)〉 = 3.417 ± 0.006 and 〈log ε (Cr I, lower level excitation potential E. P. >30 eV)〉 = 3.3743±30.011 for this dwarf star. We find a correlation of Cr with the iron-peak element Ti, suggesting an associated nucleosynthetic production. Four iron-peak elements (Cr along with Ti, V, and Sc) appear to have a similar (or correlated) production history-other iron-peak elements appear not to be associated with Cr.

Effects of dietary chromium (III) picolinate on growth performance, respiratory rate, plasma variables, and carcass traits of pigs fed high-fat diets.

PubMed

Kim, Beob G; Lindemann, Merlin D; Cromwell, Gary L

2010-02-01

We investigated the effects of supplemental chromium (Cr) as Cr (III) picolinate on pigs fed high-fat diets (HFD) in a 56-day experiment. Thirty-two crossbred pigs (9.6 kg) were allotted to four treatments with four blocks and two pigs/pen. Treatments included: (1) low-fat diet (fat < 3.5%; LFD) with no Cr, (2) HFD (fat > 30%) with no Cr, (3) HFD with 1,000 ppb Cr, and (4) HFD with 2,000 ppb Cr. Pigs fed HFD gained weight faster, consumed less, and had lower feed:gain (p < 0.05). Pigs fed HFD had higher respiration rates than pigs fed LFD on d 41 (p < 0.05). Plasma insulin on d 14 linearly decreased with Cr (p = 0.05). Plasma cholesterol concentrations were higher in the pigs fed HFD than those fed LFD, but were largely unaffected by supplemental Cr. Consumption of HFD resulted in greater carcass weight, perirenal fat, and backfat measures (p < 0.01) compared with the LFD group. Cr resulted in linear reductions of hot carcass weight (p = 0.08) and average backfat (p < 0.05). The effects of Cr on carcass fat measures were more pronounced in castrated males than in females. These results indicate that Cr attenuates some effects of a HFD, mainly body fat accretion of pigs, and especially in castrated pigs.

A combined APT and SANS investigation of α' phase precipitation in neutron-irradiated model FeCrAl alloys

DOE PAGES

Briggs, Samuel A.; Edmondson, Philip D.; Littrell, Kenneth C.; ...

2017-03-01

Here, FeCrAl alloys are currently under consideration for accident-tolerant fuel cladding applications in light water reactors owing to their superior high-temperature oxidation and corrosion resistance compared to the Zr-based alloys currently employed. However, their performance could be limited by precipitation of a Cr-rich α' phase that tends to embrittle high-Cr ferritic Fe-based alloys. In this study, four FeCrAl model alloys with 10–18 at.% Cr and 5.8–9.3 at.% Al were neutron-irradiated to nominal damage doses up to 7.0 displacements per atom at a target temperature of 320 °C. Small angle neutron scattering techniques were coupled with atom probe tomography to assessmore » the composition and morphology of the resulting α' precipitates. It was demonstrated that Al additions partially destabilize the α' phase, generally resulting in precipitates with lower Cr contents when compared with binary Fe-Cr systems. The precipitate morphology evolution with dose exhibited a transient coarsening regime akin to previously observed behavior in aged Fe-Cr alloys. Similar behavior to predictions of the LSW/UOKV models suggests that α' precipitation in irradiated FeCrAl is a diffusion-limited process with coarsening mechanisms similar to those in thermally aged high-Cr ferritic alloys.« less

The effects of dietary supplementation with chromium picolinate throughout gestation on productive performance, Cr concentration, serum parameters, and colostrum composition in sows.

PubMed

Wang, Liansheng; Shi, Zhan; Jia, Zhiqiang; Su, Binchao; Shi, Baoming; Shan, Anshan

2013-07-01

The objective of this study was to determine the effects of supplemental chromium as chromium picolinate (CrPic) on productive performance, chromium (Cr) concentration, serum parameters, and colostrum composition in sows. Thirty Yorkshire sows were bred with semen from a pool of Landrace boars. The sows were equally grouped and treated with either a diet containing 0 (control) or 400 ppb dietary Cr supplementation throughout gestation. The sows received the same basal diet based on corn-DDGS meal. Supplemental CrPic increased (P < 0.05) the sow body mass gain from the insemination to the day 110 of gestation in sows. No differences (P > 0.50) were observed in the gestation interval, sow mass, and backfat at insemination, after farrowing, at weaning and lactation loss. The number of piglets born alive, piglets per litter at weaning, and litter weaned mass were increased (P < 0.05) for those supplemented with CrPic compared with the control. However, the total number of piglets born, total born litter mass, average piglet birth body mass, born alive litter mass, and average born alive piglet mass did not differ among the treatments (P > 0.05). The placental masses of sows were similar among treatments (P > 0.05). Dietary supplementation with CrPic throughout gestation in sows showed increased (P < 0.01) concentration of Cr in the colostrum or serum at days 70 and 110. Compared with the control group, dietary supplementation with CrPic throughout gestation in sows decreased (P < 0.05) the serum insulin concentration, the glucose or serum urea nitrogen concentration at days 70 and 110. However, no differences (P > 0.05) were observed in total protein concentration among treatments. No differences (P > 0.05) were observed in total solids, protein, fat or lactose among sows fed the diets supplemented with CrPic compared with the control. This exciting finding provides evidence for an increase in mass gain and live-born piglets in sows supplemented with CrPic throughout gestation.

Tribological and Wear Performance of Nanocomposite PVD Hard Coatings Deposited on Aluminum Die Casting Tool.

PubMed

Paiva, Jose Mario; Fox-Rabinovich, German; Locks Junior, Edinei; Stolf, Pietro; Seid Ahmed, Yassmin; Matos Martins, Marcelo; Bork, Carlos; Veldhuis, Stephen

2018-02-28

In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,Al)N deposited by physical vapor deposition (PVD) have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel) by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC) and one central rotating cathode (CERC). The research was performed in two stages: in the first stage, the outlined coatings were characterized regarding their chemical composition, morphology, and structure using glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM), and X-ray diffraction (XRD), respectively. Surface morphology and mechanical properties were evaluated by atomic force microscopy (AFM) and nanoindentation. The coating adhesion was studied using Mersedes test and scratch testing. During the second stage, industrial tests were carried out for coated die casting molds. In parallel, tribological tests were also performed in order to determine if a correlation between laboratory and industrial tests can be drawn. All of the results were compared with a benchmark monolayer AlCrN coating. The data obtained show that the best performance was achieved for the AlCrN/Si₃N₄ nanocomposite coating that displays an optimum combination of hardness, adhesion, soldering behavior, oxidation resistance, and stress state. These characteristics are essential for improving the die mold service life. Therefore, this coating emerges as a novelty to be used to protect aluminum die casting molds.

Evaluation on the Effect of Composition on Radiation Hardening and Embrittlement in Model FeCrAl Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Field, Kevin G.; Briggs, Samuel A.; Edmondson, Philip

2015-09-18

This report details the findings of post-radiation mechanical testing and microstructural characterization performed on a series of model and commercial FeCrAl alloys to assist with the development of a cladding technology with enhanced accident tolerance. The samples investigated include model alloys with simple ferritic grain structure and two commercial alloys with minor solute additions. These samples were irradiated in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) up to nominal doses of 7.0 dpa near or at Light Water Reactor (LWR) relevant temperatures (300-400 C). Characterization included a suite of techniques including small angle neutron scatteringmore » (SANS), atom probe tomography (APT), and transmission based electron microscopy techniques. Mechanical testing included tensile tests at room temperature on sub-sized tensile specimens. The goal of this work was to conduct detailed characterization and mechanical testing to begin establishing empirical and/or theoretical structure-property relationships for radiation-induced hardening and embrittlement in the FeCrAl alloy class. Development of such relationships will provide insight on the performance of FeCrAl alloys in an irradiation environment and will enable further development of the alloy class for applications within a LWR environment. A particular focus was made on establishing trends, including composition and radiation dose. The report highlights in detail the pertinent findings based on this work. This report shows that radiation hardening in the alloys is primarily composition dependent due to the phase separation in the high-Cr FeCrAl alloys. Other radiation induced/enhanced microstructural features were less dependent on composition and when observed at low number densities, were not a significant contributor to the observed mechanical responses. Pre-existing microstructure in the alloys was found to be important, with grain boundaries and pre-existing dislocation networks acting as defect sinks, resulting in variations in the observed microstructures after irradiation. Dose trends were also observed, with increasing radiation dose promoting changes in the size and number density of the Cr-rich α' precipitates. Based on the microstructural analysis, performed tensile testing, and prior knowledge from FeCr literature it was hypothesized that the formation of the Cr-rich α' precipitates could lead to significant radiation-induced embrittlement in the alloys, and this could be composition dependent, a result which would mirror the trends observed for radiation-induced hardening. Due to the limited database on embrittlement in the FeCrAl alloy class after irradiation, a series of radiation experiments have been implemented. The overarching point of view within this report is the radiation tolerance of FeCrAl is complex, with many mechanisms and factors to be considered at once. Further development of the FeCrAl alloy class for enhanced accident tolerant applications requires detailed, single (or at least limited) variable experiments to fully comprehend and predict the performance of this alloy in LWRs. This report has been submitted as fulfillment of milestone M2FT-15OR0202321 titled, Summary report on the effect of composition on the irradiation embrittlement of Gen 1 ATF FeCrAl for the Department of Energy Office of Nuclear Energy, Advanced Fuel Campaign of the Fuel Cycle R&D program.« less

[Double-antigen sandwich ELISA for detecting Aspergillus fumigatus anti-Afmp1cr and Afmp2cr antibodies].

PubMed

Yang, Mei; Wang, Zhuoya; Hao, Wei; Wang, Yanfang; Huang, Li; Cai, Jianpiao; Jiang, Lingxiao; Che, Xiaoyan; Zhong, Xiaozhu; Yu, Nan

2014-05-01

To establish two double-antigen sandwich ELISA systems to detect anti-Afmp1cr and Afmp2cr antibodies of Aspergillus fumigatus. Recombinant Afmp1cr and Afmp2cr proteins of A.fumigatus expressed in Pichia pastoris were obtained. Double-antigen sandwich ELISA systems for detecting specific anti-Afmp1cr and anti-Afmp2cr antibodies were developed after chessboard titrating to determine the appropriate concentrations of the recombinant proteins and HRP-labeled proteins. The sensitivity of the assay was evaluated using serum samples of rabbits immunized with Afmp1cr and Afmp2cr. The specificity of the assay was evaluated by detecting serum samples from healthy donors and patients with other pathogenic fungal and baterial infections. The performance of the two ELISA kits was furthered evaluated using serum samples from patients with suspected Aspergillus infection. The established ELISA kits were capable of detecting anti-Afmp1cr and anti-Afmp2cr antibodies in immunized rabbit serum at the maximum dilutions of 800 and 3200, respectively. No cross-reactivity was observed in detecting serum from patients with other pathogenic fungal or bactetial infections. Both of the two kits yielded positive results in sera from two established Aspergillus-infected cases and a suspected case. Two antibody-capture ELISA kits were developed for the laboratory diagnosis of A.fumigatus infection and can be potentially useful in the clinical diagnosis of Aspergillosis infections.

A comprehensive study of piezomagnetic response in CrPS4 monolayer: mechanical, electronic properties and magnetic ordering under strains

NASA Astrophysics Data System (ADS)

Joe, Minwoong; Lee, Hosik; Menderes Alyörük, M.; Lee, Jinhwan; Youb Kim, Sung; Lee, Changgu; Lee, Jun Hee

2017-10-01

We performed first-principles calculations to investigate the magnetic, mechanical and electronic properties of the tetrachalcogenide CrPS4. Although bulk CrPS4 has been shown to exhibit a low-dimensional antiferromagnetic (AFM) ground state where ferromagnetic (FM) Cr-chains are coupled antiferromagnetically, our calculations indicated that the monolayer can be transformed to an FM material by applying a uniaxial tensile strain of  ⩾4% along the FM Cr-chain direction. The AFM-to-FM transition is explained to be driven by an increase of the exchange interaction induced by a decrease in the distance between the FM Cr-chains. A huge nonlinear piezomagnetism was predicted at the strain-induced magnetic phase boundary. Our study provides insight about rational design of single-layer magnetic materials for a wide range of spintronic devices and energy applications.

Preparation of W/CuCrZr mono-block test mock-up using vacuum brazing technique

NASA Astrophysics Data System (ADS)

Premjit Singh, K.; Khirwadkar, S.; Bhope, Kedar; Patel, Nikunj; Mokaria, Prakash

2017-04-01

Development of the joining for W/CuCrZr mono-block PFC test mock-up is an interesting area in Fusion R&D. W/Cu bimetallic material has been prepared using OFHC Copper casting approach on the radial surface of W mono-block tile surface. The W/Cu bimetallic material has been joined with CuCrZr tube (heat sink) material with the vacuum brazing route. Vacuum brazing of W/Cu-CuCrZr has been performed @ 970°C for 10 min using NiCuMn-37 filler material under deep vacuum environment (10-6 mbar). Graphite fixture was used for OFHC Copper casting and vacuum brazing experiments. The joint integrity of W/Cu-CuCrZr mono-block mock-up of W/Cu and Cu-CuCrZr interface has been checked using ultrasonic immersion technique. The result of the experimental work is presented in the paper.

Chromium as Resonant Donor Impurity in PbTe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nielsen, M.D.; Levin, Evgenii; Jaworski, C.M.

2012-01-25

We synthesize and perform structural, thermoelectric, magnetic, and 125Te NMR characterization measurements on chromium-doped PbTe. 125Te NMR and magnetic measurements show that Pb1−xCrxTe is a solid solution up to x = 0.4 at.% and forms an n-type dilute paramagnetic semiconductor. The Cr level is resonant and pins the Fermi level about 100 meV into the conduction band at liquid nitrogen temperatures and below, but it moves into the gap as the temperature increases to 300 K. 125Te NMR spectra exhibit a Knight shift that correlates well with Hall effect measurements and resolve peaks of Te near Cr. Magnetic behavior indicatesmore » that Cr exists mainly as Cr2+. No departure from the Pisarenko relation for PbTe is observed. Secondary Cr2Te3 and Cr3+δTe4 phases are present in samples with x > 0.4%.« less

Electrophoretic deposition of carbon nanotube on reticulated vitreous carbon for hexavalent chromium removal in a biocathode microbial fuel cell

NASA Astrophysics Data System (ADS)

Fei, Kangqing; Song, Tian-shun; Wang, Haoqi; Zhang, Dalu; Tao, Ran; Xie, Jingjing

2017-10-01

For Cr(VI)-removal microbial fuel cell (MFC), a more efficient biocathode in MFCs is required to improve the Cr(VI) removal and electricity generation. RVC-CNT electrode was prepared through the electrophoretic deposition of carbon nanotube (CNT) on reticulated vitreous carbon (RVC). The power density of MFC with an RVC-CNT electrode increased to 132.1 ± 2.8 mW m-2, and 80.9% removal of Cr(VI) was achieved within 48 h; compared to only 44.5% removal of Cr(VI) in unmodified RVC. Cyclic voltammetry, energy-dispersive spectrometry and X-ray photoelectron spectrometry showed that the RVC-CNT electrode enhanced the electrical conductivity and the electron transfer rate; and provided more reaction sites for Cr(VI) reduction. This approach provides process simplicity and a thickness control method for fabricating three-dimensional biocathodes to improve the performance of MFCs for Cr(VI) removal.

Cr diffusion in MgAl2O4 synthetic spinels: preliminary results

NASA Astrophysics Data System (ADS)

Freda, C.; Celata, B.; Andreozzi, G.; Perinelli, C.; Misiti, V.

2012-04-01

Chromian spinel is an accessory phase common in crustal and mantle rocks, including peridotites, gabbros and basalts. Spinel, it has been identified as one of the most effective, sensible, and versatile petrogenetic indicator in mafic and ultramafic rock systems due to the strict interdependence between its physico-chemical properties (chemical composition, cation configuration etc.) and genetic conditions (temperature, pressure, and chemical characteristics of the system). In particular, studies on intra- and inter-crystalline Mg-Fe2+, Cr-Al exchange demonstrated the close relationship between spinel composition and both degree of partial melting and equilibrium temperature of spinel-peridotites. Moreover, studies focused on the chemical zoning of Mg-Fe2+ and/or Cr-Al components in spinel have been used, combined with a diffusion model, to provide quantitative information on peridotites and gabbros pressure-temperature paths and on deformation mechanisms. Although these potentials, most of the experimental studies have been performed on spinels hosting a limited content of divalent iron (sensu stricto, MgAl2O4), whereas the scarce studies on Cr-Al inter-diffusion coefficient have been performed at 3-7 GPa as pressure boundary condition. In order to contribute to the understanding of processes occurring in the lithospheric mantle, we have initiated an experimental research project aiming at determining the Cr-Al inter-diffusion in spinel at 2 GPa pressure and temperature ranging from 1100 to 1250 °C. The experiments were performed in a end-loaded piston cylinder by using a 19 mm assembly and graphite-Pt double capsules. As starting materials we used synthetic Mg-Al spinel (200-300 μm in size) and Cr2O3 powder. Microanalyses of experimental charge were performed on polished carbon-coated mounts by electronic microprobe. Line elemental analyses were made perpendicular to the contact surface between Cr2O3 powder and spinel, at interval of 2 μm. By processing these preliminary data, we have estimated a diffusion coefficient of chromium (D) of 7.6·10-15 m2s-1.

Identifying a novel role for X-prolyl aminopeptidase (Xpnpep) 2 in CrVI-induced adverse effects on germ cell nest breakdown and follicle development in rats.

PubMed

Banu, Sakhila K; Stanley, Jone A; Sivakumar, Kirthiram K; Arosh, Joe A; Barhoumi, Rola; Burghardt, Robert C

2015-03-01

Environmental exposure to endocrine-disrupting chemicals (EDCs) is one cause of premature ovarian failure (POF). Hexavalent chromium (CrVI) is a heavy metal EDC widely used in more than 50 industries, including chrome plating, welding, wood processing, and tanneries. Recent data from U.S. Environmental Protection Agency indicate increased levels of Cr in drinking water from several American cities, which potentially predispose residents to various health problems. Recently, we demonstrated that gestational exposure to CrVI caused POF in F1 offspring. The current study was performed to identify the molecular mechanism behind CrVI-induced POF. Pregnant rats were treated with 25 ppm of potassium dichromate from Gestational Day (GD) 9.5 to GD 14.5 through drinking water, and the fetuses were exposed to CrVI through transplacental transfer. Ovaries were removed from the fetuses or pups on Embryonic Day (ED) 15.5, ED 17.5, Postnatal Day (PND) 1, PND 4, or PND 25, and various analyses were performed. Results showed that gestational exposure to CrVI: 1) increased germ cell/oocyte apoptosis and advanced germ cell nest (GCN) breakdown; 2) increased X-prolyl aminopeptidase (Xpnpep) 2, a POF marker in humans, during GCN breakdown; 3) decreased Xpnpep2 during postnatal follicle development; and 4) increased colocalization of Xpnpep2 with Col3 and Col4. We also found that Xpnpep2 inversely regulated the expression of Col1, Col3, and Col4 in all the developmental stages studied. Thus, CrVI advanced GCN breakdown and increased follicle atresia in F1 female progeny by targeting Xpnpep2. © 2015 by the Society for the Study of Reproduction, Inc.

Radiographic and magnetic resonance imaging predicts severity of cruciate ligament fiber damage and synovitis in dogs with cranial cruciate ligament rupture

PubMed Central

Racette, Molly A.; Hans, Eric C.; Volstad, Nicola J.; Holzman, Gerianne; Bleedorn, Jason A.; Schaefer, Susan L.; Waller, Kenneth R.; Hao, Zhengling; Block, Walter F.

2017-01-01

Cruciate ligament rupture (CR) and associated osteoarthritis (OA) is a common condition in dogs. Dogs frequently develop a second contralateral CR. This study tested the hypothesis that the degree of stifle synovitis and cranial cruciate ligament (CrCL) matrix damage in dogs with CR is correlated with non-invasive diagnostic tests, including magnetic resonance (MR) imaging. We conducted a prospective cohort study of 29 client-owned dogs with an unstable stifle due to complete CR and stable contralateral stifle with partial CR. We evaluated correlation of stifle synovitis and CrCL fiber damage with diagnostic tests including bilateral stifle radiographs, 3.0 Tesla MR imaging, and bilateral stifle arthroscopy. Histologic grading and immunohistochemical staining for CD3+ T lymphocytes, TRAP+ activated macrophages and Factor VIII+ blood vessels in bilateral stifle synovial biopsies were also performed. Serum and synovial fluid concentrations of C-reactive protein (CRP) and carboxy-terminal telopeptide of type I collagen (ICTP), and synovial total nucleated cell count were determined. Synovitis was increased in complete CR stifles relative to partial CR stifles (P<0.0001), although total nucleated cell count in synovial fluid was increased in partial CR stifles (P<0.01). In partial CR stifles, we found that 3D Fast Spin Echo Cube CrCL signal intensity was correlated with histologic synovitis (SR = 0.50, P<0.01) and that radiographic OA was correlated with CrCL fiber damage assessed arthroscopically (SR = 0.61, P<0.001). Taken together, results of this study show that clinical diagnostic tests predict severity of stifle synovitis and cruciate ligament matrix damage in stable partial CR stifles. These data support use of client-owned dogs with unilateral complete CR and contralateral partial CR as a clinical trial model for investigation of disease-modifying therapy for partial CR. PMID:28575001

Radiographic and magnetic resonance imaging predicts severity of cruciate ligament fiber damage and synovitis in dogs with cranial cruciate ligament rupture.

PubMed

Sample, Susannah J; Racette, Molly A; Hans, Eric C; Volstad, Nicola J; Holzman, Gerianne; Bleedorn, Jason A; Schaefer, Susan L; Waller, Kenneth R; Hao, Zhengling; Block, Walter F; Muir, Peter

2017-01-01

Cruciate ligament rupture (CR) and associated osteoarthritis (OA) is a common condition in dogs. Dogs frequently develop a second contralateral CR. This study tested the hypothesis that the degree of stifle synovitis and cranial cruciate ligament (CrCL) matrix damage in dogs with CR is correlated with non-invasive diagnostic tests, including magnetic resonance (MR) imaging. We conducted a prospective cohort study of 29 client-owned dogs with an unstable stifle due to complete CR and stable contralateral stifle with partial CR. We evaluated correlation of stifle synovitis and CrCL fiber damage with diagnostic tests including bilateral stifle radiographs, 3.0 Tesla MR imaging, and bilateral stifle arthroscopy. Histologic grading and immunohistochemical staining for CD3+ T lymphocytes, TRAP+ activated macrophages and Factor VIII+ blood vessels in bilateral stifle synovial biopsies were also performed. Serum and synovial fluid concentrations of C-reactive protein (CRP) and carboxy-terminal telopeptide of type I collagen (ICTP), and synovial total nucleated cell count were determined. Synovitis was increased in complete CR stifles relative to partial CR stifles (P<0.0001), although total nucleated cell count in synovial fluid was increased in partial CR stifles (P<0.01). In partial CR stifles, we found that 3D Fast Spin Echo Cube CrCL signal intensity was correlated with histologic synovitis (SR = 0.50, P<0.01) and that radiographic OA was correlated with CrCL fiber damage assessed arthroscopically (SR = 0.61, P<0.001). Taken together, results of this study show that clinical diagnostic tests predict severity of stifle synovitis and cruciate ligament matrix damage in stable partial CR stifles. These data support use of client-owned dogs with unilateral complete CR and contralateral partial CR as a clinical trial model for investigation of disease-modifying therapy for partial CR.

Activated carbon with excellent chromium(VI) adsorption performance prepared by acid-base surface modification.

PubMed

Liu, S X; Chen, X; Chen, X Y; Liu, Z F; Wang, H L

2007-03-06

In the present work, activated carbon (AC) with excellent Cr(VI) adsorption performance especially at low concentrations was prepared by an acid-base surface modification method. Raw activated carbon (AC(0)) was first oxidized in boiling HNO(3) (AC(1)), then treated with a mixture of NaOH and NaCl (AC(2)). Batch equilibrium and continuous column adsorption were conducted to evaluate the adsorption performance. Boehm titration, elemental analysis, and N(2)/77K adsorption isotherm methods were used to characterize the surface properties and pore structure of modified ACs. The results revealed that the modified AC exhibited excellent Cr(VI) adsorption performance in terms of adsorption capacity and adsorption rate: AC(2)>AC(1)>AC(0). Modification caused S(BET) to decrease and the total number of surface oxygen acidic groups to increase. HNO(3) oxidization produced positive acid groups, and subsequently NaOH treatment replaced H(+) of surface acid groups by Na(+), and the acidity of AC decreased. The main cause of higher Cr(VI) adsorption capacity and rate for AC(2) was the presence of more oxygen surface acidic groups and suitable surface acidity. HNO(3)-NaOH modification shows potential for the preparation of high quality AC for the effective removal of low concentrations of Cr(VI).

Indirect effects of elevated body mass index on memory performance through altered cerebral metabolite concentrations.

PubMed

Gonzales, Mitzi M; Tarumi, Takashi; Eagan, Danielle E; Tanaka, Hirofumi; Vaghasia, Miral; Haley, Andreana P

2012-09-01

Elevated body mass index (BMI) at midlife is associated with increased risk of cognitive decline in later life. The goal of the current study was to assess mechanisms of early brain vulnerability by examining if higher BMI at midlife affects current cognitive performance through alterations in cerebral neurochemistry. Fifty-five participants, aged 40 to 60 years, underwent neuropsychological testing, health screen, and proton magnetic resonance spectroscopy examining N-acetylaspartate, creatine (Cr), myo-inositol (mI), choline, and glutamate concentrations in occipitoparietal gray matter. Concentrations of N-acetylaspartate, choline, mI, and glutamate were calculated as a ratio over Cr and examined in relation to BMI using multivariate regression analyses. Structural equation modeling was used to determine if BMI had an indirect effect on cognition through cerebral metabolite levels. Higher BMI was associated with elevations in mI/Cr (F(5,45) = 3.843, p = .006, β = 0.444, p = .002), independent of age, sex, fasting glucose levels, and systolic blood pressure. Moreover, a χ(2) difference test of the direct and indirect structural equation models revealed that BMI had an indirect effect on global cognitive performance (Δχ(2) = 19.939, df = 2, p < .001). Subsequent follow-up analyses revealed that this effect was specific to memory (Δχ(2) = 22.027, df = 2, p < .001). Higher BMI was associated with elevations in mI/Cr concentrations in the occipitoparietal gray matter and indirectly related to poorer memory performance through mI/Cr levels, potentially implicating plasma hypertonicity and neuroinflammation as mechanisms underlying obesity-related brain vulnerability.

Sensitivity analysis of FeCrAl cladding and U3Si2 fuel under accident conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gamble, Kyle Allan Lawrence; Hales, Jason Dean

2016-08-01

The purpose of this milestone report is to highlight the results of sensitivity analyses performed on two accident tol- erant fuel concepts: U3Si2 fuel and FeCrAl cladding. The BISON fuel performance code under development at Idaho National Laboratory was coupled to Sandia National Laboratories’ DAKOTA software to perform the sensitivity analyses. Both Loss of Coolant (LOCA) and Station blackout (SBO) scenarios were analyzed using main effects studies. The results indicate that for FeCrAl cladding the input parameters with greatest influence on the output metrics of interest (fuel centerline temperature and cladding hoop strain) during the LOCA were the isotropic swellingmore » and fuel enrichment. For U3Si2 the important inputs were found to be the intergranular diffusion coefficient, specific heat, and fuel thermal conductivity. For the SBO scenario, Young’s modulus was found to be influential in FeCrAl in addition to the isotropic swelling and fuel enrichment. Contrarily to the LOCA case, the specific heat of U3Si2 was found to have no effect during the SBO. The intergranular diffusion coefficient and fuel thermal conductivity were still found to be of importance. The results of the sensitivity analyses have identified areas where further research is required including fission gas behavior in U3Si2 and irradiation swelling in FeCrAl. Moreover, the results highlight the need to perform the sensitivity analyses on full length fuel rods for SBO scenarios.« less

Cr-substituted LiCoPO4 core with a conductive carbon layer towards high-voltage lithium-ion batteries

NASA Astrophysics Data System (ADS)

Wang, Yue; Chen, Junhong; Qiu, Jingyi; Yu, Zhongbao; Ming, Hai; Li, Meng; Zhang, Songtong; Yang, Yusheng

2018-02-01

Electrical and ionic conductivity are two major limiting factors for LiCoPO4 cathode material. To overcome these shortcomings, a Cr-substituted LiCoPO4 core with a conductive carbon layer cathode material is synthesized using the sol-gel method. The physical chemistry properties of these materials are systematically investigated by using various characterization methods. For instance, the XRD and Rietveld refinement results reveal that Cr successfully substitutes the Co within the LiCoPO4 core to form LiCo1-1.5xCrxPO4/C (x = 0, 0.02, 0.04, 0.06) without changing the olivine structure but exhibits a decrease in the unit cell volume with increasing Cr substitution. SEM and TEM images indicate that Cr substitution does not lead to changes in the basic morphology of LiCo1-1.5xCrxPO4/C (x = 0, 0.02, 0.04, 0.06) material, which is composed of agglomerated nanoparticles with an 8 nm carbon layer on the surface. The EDS and XPS results confirm that Cr is uniformly distributed on the surface and that the oxidation state of Cr is +3. FTIR spectra indicate that the antisite defect concentration decreases with increasing Cr substitution. Furthermore, Cr substitution significantly improves the electrochemical performances of LiCo1-1.5xCrxPO4/C (x = 0.02, 0.04, 0.06) cathode. Notably, the LiCo0.94Cr0.04PO4/C delivers an initial discharge capacity of 144 mA h g-1 at 0.1 C and shows a capacity retention of 71% after 100 cycles between 3.0 and 5.0 V. The CV and EIS results indicate that the polarization is reduced and that the electronic and ionic conductivities are improved by Cr substitution. The good electrochemical performances for Cr-substituted LiCoPO4/C electrodes are attributed to the lower antisite defect concentration, as the reduction of polarization, the improvement of electronic and ion conductivity and the uniform carbon layer. These features will accelerate the commercial application of LiCoPO4 towards the start-art of the high voltage lithium-ion batteries.

Development of analytical procedures for the determination of hexavalent chromium in corrosion prevention coatings used in the automotive industry.

PubMed

Séby, F; Castetbon, A; Ortega, R; Guimon, C; Niveau, F; Barrois-Oudin, N; Garraud, H; Donard, O F X

2008-05-01

The European directive 2000/53/EC limits the use of Cr(VI) in vehicle manufacturing. Although a maximum of 2 g of Cr(VI) was authorised per vehicle for corrosion prevention coatings of key components, since July 2007 its use has been prohibited except for some particular applications. Therefore, the objective of this work was to develop direct analytical procedures for Cr(VI) determination in the different steel coatings used for screws. Instead of working directly with screws, the optimisation of the procedures was carried out with metallic plates homogeneously coated to improve the data comparability. Extraction of Cr(VI) from the metallic parts was performed by sonication. Two extraction solutions were tested: a direct water extraction solution used in standard protocols and an ammonium/ammonia buffer solution at pH 8.9. The extracts were further analysed for Cr speciation by high-performance liquid chromatography (HPLC) inductively coupled plasma (ICP) atomic emission spectrometry or HPLC ICP mass spectrometry depending on the concentration level. When possible, the coatings were also directly analysed by solid speciation techniques (X-ray photoelectron spectroscopy, XPS, and X-ray absorption near-edge structure, XANES) for validation of the results. Very good results between the different analytical approaches were obtained for the sample of coating made up of a heated paint containing Zn, Al and Cr when using the extracting buffer solution at pH 8.9. After a repeated four-step extraction procedure on the same portion test, taking into account the depth of the surface layer reached, good agreement with XPS and XANES results was obtained. In contrast, for the coatings composed of an alkaline Zn layer where Cr(VI) and Cr(III) are deposited, only the extraction procedure using water allowed the detection of Cr(VI). To elucidate the Cr(VI) reduction during extraction at pH 8.9, the reactivity of Cr(VI) towards different species of Zn generally present in the coatings (metallic Zn and zinc oxide) was studied. The results showed that metallic Zn rapidly reduces Cr(VI), whereas this reaction is less evident in the presence of zinc oxide. Water was then retained for coatings containing metallic Zn.

Preparation of multilayered nanocrystalline thin films with composition-modulated interfaces

NASA Astrophysics Data System (ADS)

Biro, D.; Barna, P. B.; Székely, L.; Geszti, O.; Hattori, T.; Devenyi, A.

2008-06-01

The properties of multilayer thin film structures depend on the morphology and structure of interfaces. A broad interface, in which the composition is varying, can enhance, e.g., the hardness of multilayer thin films. In the present experiments multilayers of TiAlN and CrN as well as TiAlN, CrN and MoS 2 were studied by using unbalanced magnetron sputter sources. The sputter sources were arranged side by side on an arc. This arrangement permits development of a transition zone between the layers, where the composition changes continuously. The multilayer system was deposited by one-fold oscillating movement of substrates in front of sputter sources. Thicknesses of layers could be changed both by oscillation frequency and by the power applied to sputter sources. Ti/Al: 50/50 at%, pure chromium and MoS 2 targets were used in the sputter sources. The depositions were performed in an Ar-N 2 mixture at 0.22 Pa working pressure. The sputtering power of the TiAl source was feed-back adjusted in fuzzy-logic mode in order to avoid fluctuation of the TiAl target sputter rate due to poisoning of the target surface. Structure characterization of films deposited on <1 0 0> Si wafers covered by thermally grown SiO 2 was performed by cross-sectional transmission electron microscopy. At first a 100 nm thick Cr base layer was deposited on the substrate to improve adhesion, which was followed by a CrN transition layer. The CrN transition layer was followed by a 100 nm thick TiAlN/CrN multilayer system. The TiAlN/CrN/MoS 2 multilayer system was deposited on the surface of this underlayer system. The underlayer systems Cr, CrN and TiAlN/CrN were crystalline with columnar structure according to the morphology of zone T of the structure zone models. The column boundaries contained segregated phases showing up in the under-focused TEM images. The surface of the underlayer system was wavy due to dome-shaped columns. The nanometer-scaled TiAlN/CrN/MoS 2 multilayer system followed this waviness. Crystallinity of the TiAlN and CrN layers in the multilayer system decreases with increasing thickness of the MoS 2 layer.

Evidence for Metabolic Hypothalamo-Amygdala Dysfunction in Narcolepsy

PubMed Central

Poryazova, Rositsa; Schnepf, Betina; Werth, Esther; Khatami, Ramin; Dydak, Ulrike; Meier, Dieter; Boesiger, Peter; Bassetti, Claudio L.

2009-01-01

Study Objectives: Proton resonance spectroscopy (1H-MRS) allows noninvasive chemical tissue analysis in the living brain. As neuronal loss and gliosis have been described in narcolepsy, metabolites of primary interest are N-acetylaspartate (NAA), a marker of neuronal integrity and myo-Inositol (mI), a glial marker and second messenger involved in the regulation of intracellular calcium. One 1H-MRS study in narcolepsy found no metabolic changes in the pontomedullary junction. Another study showed a reduction in NAA/creatine-phosphocreatine (Cr) in the hypothalamus of narcolepsy patients with cataplexy. We aimed to test for metabolic changes in specific brain areas, “regions of interest,” thought to be involved in emotional processing, sleep regulation and pathophysiology of narcolepsy: hypothalamus, pontomesencephalic junction and both amygdalae. Design: We performed 1H-MRS using a 3T Philips Achieva whole body MR scanner. Single-voxel proton MR spectra were acquired and quantified with LCModel to determine metabolite concentration ratios. Setting: The participants in the study were recruited at the outpatient clinic for sleep medicine, Department of Neurology and magnetic resonance spectroscopy was performed at the MRI facility, University Hospital Zurich. Participants: 1H-MRS was performed in fourteen narcolepsy patients with cataplexy, CSF hypocretin deficiency (10/10) and HLA-DQB1*0602 positivity (14/14) and 14 age, gender and body mass index matched controls. Patients were treatment naïve or off therapy for at least 14 days before scanning. Measurements and Results: No differences were observed in the regions of interest for (total NAA)/Cr ratios. Myo-Inositol (mI)/Cr was significantly lower in the right amygdala of the patients, compared to controls (P < 0.042). Significant negative correlations only in the patients group were found between (total NAA)/Cr in hypothalamus and mI/Cr in the right amygdala (r = −0.89, P < 0.001), between mI/Cr in hypothalamus and (total NAA)/Cr in the right amygdala (r = −63, P < 0.05) and between mI/Cr in the left amygdala and total NAA)/Cr in the pontomesencephalic junction (r = −0.69, P < 0.05). Conclusion: Our findings suggest amygdala involvement and possible hypothalamo-amygdala dysfunction in narcolepsy. Citation: Poryazova R; Werth E; Khatami R; Dydak U; Meier D; Boesiger P; Bassetti CL. Evidence for metabolic hypothalamo-amygdala dysfunction in narcolepsy. SLEEP 2009;32(5):607-613. PMID:19480227

Lithium, phenserine, memantine and pioglitazone reverse memory deficit and restore phospho-GSK3β decreased in hippocampus in intracerebroventricular streptozotocin induced memory deficit model.

PubMed

Ponce-Lopez, Teresa; Liy-Salmeron, Gustavo; Hong, Enrique; Meneses, Alfredo

2011-12-02

Intracerebroventricular (ICV) streptozotocin (STZ) treated rat has been described as a suitable model for sporadic Alzheimer's disease (AD). Central application of STZ has demonstrated behavioral and neurochemical features that resembled those found in human AD. Chronic treatments with antioxidants, acetylcholinesterase (AChE) inhibitors, or improving glucose utilization drugs have reported a beneficial effect in ICV STZ-treated rats. In the present study the post-training administration of a glycogen synthase kinase (GSK3) inhibitor, lithium; antidementia drugs: phenserine and memantine, and insulin sensitizer, pioglitazone on memory function of ICV STZ-rats was assessed. In these same animals the phosphorylated GSK3β (p-GSK3β) and total GSK3β levels were determined, and importantly GSK3β regulates the tau phosphorylation responsible for neurofibrillary tangle formation in AD. Wistar rats received ICV STZ application (3mg/kg twice) and 2 weeks later short- (STM) and long-term memories (LTM) were assessed in an autoshaping learning task. Animals were sacrificed immediately following the last autoshaping session, their brains removed and dissected. The enzymes were measured in the hippocampus and prefrontal cortex (PFC) by western blot. ICV STZ-treated rats showed a memory deficit and significantly decreased p-GSK3β levels, while total GSK3β did not change, in both the hippocampus and PFC. Memory impairment was reversed by lithium (100mg/kg), phenserine (1mg/kg), memantine (5mg/kg) and pioglitazone (30 mg/kg). The p-GSK3β levels were restored by lithium, phenserine and pioglitazone in the hippocampus, and restored by lithium in the PFC. Memantine produced no changes in p-GSK3β levels in neither the hippocampus nor PFC. Total GSK3β levels did not change with either drug. Altogether these results show the beneficial effects of drugs with different mechanisms of actions on memory impairment induced by ICV STZ, and restored p-GSK3β levels, a kinase key of signaling cascade of insulin receptor. 2011 Elsevier B.V. All rights reserved.

Developmental Lead Exposure Alters Methamphetamine Self-administration in the Male Rat: Acquisition and Reinstatement

PubMed Central

Rocha, Angelica; Valles, Rodrigo; Bratton, Gerald R.; Nation, Jack R.

2010-01-01

The rate of acquisition of drug self-administration and the return to drug seeking are important elements of the overall drug profile, and are essential factors in understanding risks associated with drug abuse. Experiment 1 examined the effects of perinatal (gestation/lactation) lead exposure on adult rates of acquisition of intravenous (i.v.) methamphetamine self-administration. Experiment 2 investigated the effects of perinatal lead exposure on drug-maintained responding in a reinstatement (relapse) paradigm. In Experiment 1, female rats were gavaged daily with 0 or 16-mg lead for 30 days prior to breeding with nonexposed males. Lead exposure continued through gestation and lactation and was discontinued at weaning (postnatal day [PND] 21). Male rats born to control or lead-exposed dams were tested daily as adults in an acquisition paradigm that incorporated both Pavlovian and operant components. An initial 3-hr autoshaping period preceded a 3-hr self-administration period. For 35 daily training sessions i.v. methamphetamine infusions [inf] (0.02 mg/kg) were paired with the extension and retraction of a lever (autoshaping), while inf occurred during self-administration only when a lever press was executed (FR-1). In Experiment 2 animals developmentally exposed to lead were trained on a FR-2 to self-administer methamphetamine (0.04 mg/kg/inf) and then placed on an extinction schedule prior to receiving intraperitoneal (i.p.) priming injections of saline, 0.50, 1.00, or 1.50 mg/kg methamphetamine. The findings from Experiment 1 showed that acquisition was delayed in rats born to lead-exposed dams gavaged daily with 16-mg lead throughout gestation and lactation when a 0.02 mg/kg/inf of methamphetamine served as the reinforcement outcome. Additional data from Experiment 2 indicated priming cues (injections of methamphetamine [i.p.]) administered after extinction were less likely to occasion a return to drug seeking (relapse) in the 16-mg group relative to the 0-mg control group. These results suggest perinatal lead exposure alters patterns of methamphetamine self-administration during the adult cycle. PMID:18242880

Prefrontal cortex, caloric restriction and stress during aging: studies on dopamine and acetylcholine release, BDNF and working memory.

PubMed

Del Arco, Alberto; Segovia, Gregorio; de Blas, Marta; Garrido, Pedro; Acuña-Castroviejo, Dario; Pamplona, Reinald; Mora, Francisco

2011-01-01

This study was designed to investigate whether long-term caloric restriction during the life span of the rat changes the effects of an acute mild stress on the release of dopamine and acetylcholine in the prefrontal cortex (PFC) and on working memory performance. Spontaneous motor activity was also monitored and levels of BDNF measured in the prefrontal cortex, amygdala and hippocampus. Male Wistar rats (3 months of age) were housed during 3, 12, 21 and 27 months (6, 15, 24 and 30 months of age at the end of housing) in caloric restriction (CR; 40% food intake restriction) or control conditions. After behavioural testing, animals were further subdivided into two other groups. In one of the groups BDNF protein levels were determined. In the other group rats were implanted with guide cannulas into the PFC to perform microdialysis experiments. In CR rats the release of dopamine produced by handling stress did not differ from the response found in control rats of 6, 15 and 24 months of age. The release of acetylcholine was not changed at the ages of 6 and 15 months but reduced at the age of 24 months. Stress did not change dopamine or acetylcholine release in CR and control rats of 30 months of age. BDNF levels were increased in the hippocampus and amygdala, but not in the PFC, of 6 and 15 months CR rats. Spontaneous motor activity was increased in all groups of CR rats. Age, however, decreased motor activity in CR and control rats. Both experimental groups showed similar working memory performance in a delayed alternation task in basal conditions and after a situation of acute stress. These results suggest that CR does not modify the function of the PFC in response to an acute stress nor the changes found as a result of the normal process of aging. Copyright © 2010 Elsevier B.V. All rights reserved.

Creatine supplementation prevents acute strength loss induced by concurrent exercise.

PubMed

de Salles Painelli, Vítor; Alves, Victor Tavares; Ugrinowitsch, Carlos; Benatti, Fabiana Braga; Artioli, Guilherme Giannini; Lancha, Antonio Herbert; Gualano, Bruno; Roschel, Hamilton

2014-08-01

To investigate the effect of creatine (CR) supplementation on the acute interference induced by aerobic exercise on subsequent maximum dynamic strength (1RM) and strength endurance (SE, total number of repetitions) performance. Thirty-two recreationally strength-trained men were submitted to a graded exercise test to determine maximal oxygen consumption (VO2max: 41.56 ± 5.24 ml kg(-1) min(-1)), anaerobic threshold velocity (ATv: 8.3 ± 1.18 km h(-1)), and baseline performance (control) on the 1RM and SE (4 × 80 % 1RM to failure) tests. After the control tests, participants were randomly assigned to either a CR (20 g day(-1) for 7 days followed by 5 g day(-1) throughout the study) or a placebo (PL-dextrose) group, and then completed 4 experimental sessions, consisting of a 5-km run on a treadmill either continuously (90 % ATv) or intermittently (1:1 min at vVO2max) followed by either a leg- or bench-press SE/1RM test. CR was able to maintain the leg-press SE performance after the intermittent aerobic exercise when compared with C (p > 0.05). On the other hand, the PL group showed a significant decrease in leg-press SE (p ≤ 0.05). CR supplementation significantly increased bench-press SE after both aerobic exercise modes, while the bench-press SE was not affected by either mode of aerobic exercise in the PL group. Although small increases in 1RM were observed after either continuous (bench press and leg press) or intermittent (bench press) aerobic exercise in the CR group, they were within the range of variability of the measurement. The PL group only maintained their 1RM. In conclusion, the acute interference effect on strength performance observed in concurrent exercise may be counteracted by CR supplementation.

Contribution of four lifelong factors of cognitive reserve on late cognition in normal aging and Parkinson's disease.

PubMed

Rouillard, Maud; Audiffren, Michel; Albinet, Cédric; Ali Bahri, Mohamed; Garraux, Gaëtan; Collette, Fabienne

2017-03-01

Cognitive reserve (CR) was proposed to explain how individual differences in brain function help to cope with the effects of normal aging and neurodegenerative diseases. Education, professional solicitations, and engagement in leisure and physical activities across the lifetime are considered as major determinants of this reserve. Using multiple linear regression analyses, we tested separately in healthy elderly and Parkinson's disease (PD) populations to what extent cognitive performance in several domains was explained by (a) any of these four environmental lifespan variables; (b) demographic and clinical variables (age, gender, depression score, and, for the PD group, duration of disease and dopaminergic drugs). We also tested for an interaction, if any, between these lifespan variables and brain pathology indexed by global atrophy measured from high-resolution anatomical magnetic resonance imaging. Age was negatively associated with cognitive performance in the PD group. In healthy elderly participants, we observed significant positive associations between cognitive performance and (a) education, (b) leisure activities, and (c) professional solicitation (decisional latitude). Furthermore, participants with greater brain atrophy benefited more from CR. In PD patients, education and professional solicitations contributed to cognitive performance but to a lesser extent than in controls. CR factors modulated the relationship between cognition and brain atrophy only in patients with a slight or moderate brain atrophy. Education is the CR factor that contributed the most to late cognitive functioning in both groups, closely followed by leisure activity in normal aging and professional solicitations in PD. Our results also provide evidence suggesting that the effects of CR does not express similarly in normal aging and PD. From a broader perspective, these results seem to indicate that CR factors the most consistently practiced across lifespan (education and professional solicitation) are those that are the more strongly associated to late cognitive efficiency.

Initiation of calorie restriction in middle-aged male rats attenuates aging-related motoric decline and bradykinesia without increased striatal dopamine

PubMed Central

Salvatore, Michael F.; Terrebonne, Jennifer; Fields, Victoria; Nodurft, Danielle; Runfalo, Cori; Latimer, Brian; Ingram, Donald K.

2015-01-01

Aging-related bradykinesia affects ~15% of those reaching age 65 and 50% of those reaching their 80s. Given this high risk and lack of pharmacological therapeutics, non-invasive lifestyle strategies should be identified to diminish its risk and identify the neurobiological targets to reduce aging-related bradykinesia. Early-life, long-term calorie restriction (CR) attenuates aging-related bradykinesia in rodents. Here, we addressed whether CR initiation at middle age could attenuate aging-related bradykinesia and motoric decline measured as rotarod performance. A 30% CR regimen was implemented for 6 months duration in 12-month old male Brown-Norway Fischer 344 F1 hybrid rats after establishing individual baseline locomotor activities. Locomotor capacity was assessed every 6 weeks thereafter. The ad libitum (AL) group exhibited predictably decreased locomotor activity, except movement speed, out to 18 months of age. In contrast, in the CR group, movement number and horizontal activity did not decrease during the 6-month trial and aging-related decline in rotarod performance was attenuated. The response to CR was influenced by baseline locomotor activity. The lower the locomotor activity level at baseline, the greater the response to CR. Rats in the lower 50th percentile surpassed their baseline level of activity, whereas rats in the top 50th percentile decreased at 6 weeks and then returned to baseline by 12 weeks of CR. We hypothesized that nigrostriatal dopamine tissue content would be greater in the CR group and observed a modest increase only in substantia nigra with no group differences in striatum, nucleus accumbens, or ventral tegmental area. These results indicate initiation of CR at middle age may reduce aging-related bradykinesia and, furthermore, subjects with below average locomotor activity may increase baseline activity. Sustaining nigral DA neurotransmission may be one component of preserving locomotor capabilities during aging. PMID:26610387

Optimizing Cr(VI) and Tc(VII) remediation through nano-scale biomineral engineering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cutting, R. S.; Coker, V. S.; Telling, N. D.

2009-09-09

To optimize the production of biomagnetite for the bioremediation of metal oxyanion contaminated waters, the reduction of aqueous Cr(VI) to Cr(III) by two biogenic magnetites and a synthetic magnetite was evaluated under batch and continuous flow conditions. Results indicate that nano-scale biogenic magnetite produced by incubating synthetic schwertmannite powder in cell suspensions of Geobacter sulfurreducens is more efficient at reducing Cr(VI) than either biogenic nano-magnetite produced from a suspension of ferrihydrite 'gel' or synthetic nano-scale Fe{sub 3}O{sub 4} powder. Although X-ray Photoelectron Spectroscopy (XPS) measurements obtained from post-exposure magnetite samples reveal that both Cr(III) and Cr(VI) are associated with nanoparticlemore » surfaces, X-ray Magnetic Circular Dichroism (XMCD) studies indicate that some Cr(III) has replaced octahedrally coordinated Fe in the lattice of the magnetite. Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) measurements of total aqueous Cr in the associated solution phase indicated that, although the majority of Cr(III) was incorporated within or adsorbed to the magnetite samples, a proportion ({approx}10-15 %) was released back into solution. Studies of Tc(VII) uptake by magnetites produced via the different synthesis routes also revealed significant differences between them as regards effectiveness for remediation. In addition, column studies using a {gamma}-camera to obtain real time images of a {sup 99m}Tc(VII) radiotracer were performed to visualize directly the relative performances of the magnetite sorbents against ultra-trace concentrations of metal oxyanion contaminants. Again, the magnetite produced from schwertmannite proved capable of retaining more ({approx}20%) {sup 99m}Tc(VII) than the magnetite produced from ferrihydrite, confirming that biomagnetite production for efficient environmental remediation can be fine-tuned through careful selection of the initial Fe(III) mineral substrate supplied to Fe(III)-reducing bacteria.« less

Nitrification inhibition by hexavalent chromium Cr(VI)--Microbial ecology, gene expression and off-gas emissions.

PubMed

Kim, Young Mo; Park, Hongkeun; Chandran, Kartik

2016-04-01

The goal of this study was to investigate the responses in the physiology, microbial ecology and gene expression of nitrifying bacteria to imposition of and recovery from Cr(VI) loading in a lab-scale nitrification bioreactor. Exposure to Cr(VI) in the reactor strongly inhibited nitrification performance resulting in a parallel decrease in nitrate production and ammonia consumption. Cr(VI) exposure also led to an overall decrease in total bacterial concentrations in the reactor. However, the fraction of ammonia oxidizing bacteria (AOB) decreased to a greater extent than the fraction of nitrite oxidizing bacteria (NOB). In terms of functional gene expression, a rapid decrease in the transcript concentrations of amoA gene coding for ammonia oxidation in AOB was observed in response to the Cr(VI) shock. In contrast, transcript concentrations of the nxrA gene coding for nitrite oxidation in NOB were relatively unchanged compared to Cr(VI) pre-exposure levels. Therefore, Cr(VI) exposure selectively and directly inhibited activity of AOB, which indirectly resulted in substrate (nitrite) limitation to NOB. Significantly, trends in amoA expression preceded performance trends both during imposition of and recovery from inhibition. During recovery from the Cr(VI) shock, the high ammonia concentrations in the bioreactor resulted in an irreversible shift towards AOB populations, which are expected to be more competitive in high ammonia environments. An inadvertent impact during recovery was increased emission of nitrous oxide (N2O) and nitric oxide (NO), consistent with recent findings linking AOB activity and the production of these gases. Therefore, Cr(VI) exposure elicited multiple responses on the microbial ecology, gene expression and both aqueous and gaseous nitrogenous conversion in a nitrification process. A complementary interrogation of these multiple responses facilitated an understanding of both direct and indirect inhibitory impacts on nitrification. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparison of three sampling and analytical methods for the determination of airborne hexavalent chromium.

PubMed

Boiano, J M; Wallace, M E; Sieber, W K; Groff, J H; Wang, J; Ashley, K

2000-08-01

A field study was conducted with the goal of comparing the performance of three recently developed or modified sampling and analytical methods for the determination of airborne hexavalent chromium (Cr(VI)). The study was carried out in a hard chrome electroplating facility and in a jet engine manufacturing facility where airborne Cr(VI) was expected to be present. The analytical methods evaluated included two laboratory-based procedures (OSHA Method ID-215 and NIOSH Method 7605) and a field-portable method (NIOSH Method 7703). These three methods employ an identical sampling methodology: collection of Cr(VI)-containing aerosol on a polyvinyl chloride (PVC) filter housed in a sampling cassette, which is connected to a personal sampling pump calibrated at an appropriate flow rate. The basis of the analytical methods for all three methods involves extraction of the PVC filter in alkaline buffer solution, chemical isolation of the Cr(VI) ion, complexation of the Cr(VI) ion with 1,5-diphenylcarbazide, and spectrometric measurement of the violet chromium diphenylcarbazone complex at 540 nm. However, there are notable specific differences within the sample preparation procedures used in three methods. To assess the comparability of the three measurement protocols, a total of 20 side-by-side air samples were collected, equally divided between a chromic acid electroplating operation and a spray paint operation where water soluble forms of Cr(VI) were used. A range of Cr(VI) concentrations from 0.6 to 960 microg m(-3), with Cr(VI) mass loadings ranging from 0.4 to 32 microg, was measured at the two operations. The equivalence of the means of the log-transformed Cr(VI) concentrations obtained from the different analytical methods was compared. Based on analysis of variance (ANOVA) results, no statistically significant differences were observed between mean values measured using each of the three methods. Small but statistically significant differences were observed between results obtained from performance evaluation samples for the NIOSH field method and the OSHA laboratory method.

Microstructural evolution of nanochannel CrN films under ion irradiation at elevated temperature and post-irradiation annealing

NASA Astrophysics Data System (ADS)

Tang, Jun; Hong, Mengqing; Wang, Yongqiang; Qin, Wenjing; Ren, Feng; Dong, Lan; Wang, Hui; Hu, Lulu; Cai, Guangxu; Jiang, Changzhong

2018-03-01

High-performance radiation tolerance materials are crucial for the success of future advanced nuclear reactors. In this paper, we present a further investigation that the "vein-like" nanochannel films can enhance radiation tolerance under ion irradiation at high temperature and post-irradiation annealing. The chromium nitride (CrN) nanochannel films with different nanochannel densities and the compact CrN film are chosen as a model system for these studies. Microstructural evolution of these films were investigated using Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Elastic Recoil Detection (ERD) and Grazing Incidence X-ray Diffraction (GIXRD). Under the high fluence He+ ion irradiation at 500 °C, small He bubbles with low bubble densities are observed in the irradiated nanochannel CrN films, while the aligned large He bubbles, blistering and texture reconstruction are found in the irradiated compact CrN film. For the heavy Ar2+ ion irradiation at 500 °C, the microstructure of the nanochannel CrN RT film is more stable than that of the compact CrN film due to the effective releasing of defects via the nanochannel structure. Under the He+ ion irradiation and subsequent annealing, compared with the compact film, the nanochannel films have excellent performance for the suppression of He bubble growth and possess the strong microstructural stability. Basing on the analysis on the sizes and number densities of bubbles as well as the concentrations of He retained in the nanochannel CrN films and the compact CrN film under different experimental conditions, potential mechanism for the enhanced radiation tolerance are discussed. Nanochannels play a crucial role on the release of He/defects under ion irradiation. We conclude that the tailored "vein-like" nanochannel structure may be used as advanced radiation tolerance materials for future nuclear reactors.

Polyaniline coating with various substrates for hexavalent chromium removal

NASA Astrophysics Data System (ADS)

Qiu, Bin; Xu, Cuixia; Sun, Dezhi; Wang, Qiang; Gu, Hongbo; Zhang, Xin; Weeks, Brandon L.; Hopper, Jack; Ho, Thomas C.; Guo, Zhanhu; Wei, Suying

2015-04-01

Hexavalent chromium (Cr(VI)) contamination is increasingly serious in surface water and groundwater, therefore, its removal attracts increasing attention due to its highly toxic to human health. The cost effective and sustainable adsorbents are urgently needed for the remediation of Cr(VI) pollution. Polyanline (PANI), a conductive polymer, has demonstrated a great performance on Cr(VI) removal. But the recycling is the challenge for its application due to its small size. The PANI coating with various substrates is an effective approach to solve this problem. The synthesis methods and applications of the PANI coated magnetic Fe3O4, carbon fabric and cellulose composites for the Cr(VI) removal were reviewed. Finally, this review analyzed the Cr(VI) removal mechanisms by the PANI composites considering the substrate and the PANI coating.

[Chemical Exchange Saturation Transfer Imaging of Creatine Metabolites: a 3.0 T MRI Pilot].

PubMed

Guo, Ying-kun; Li, Zhen-lin; Rong, Yu; Xia, Chun-chao; Zhang, Li-zhi; Peng, Wan-ling; Liu, Xi; Xu, Hua-yan; Zhang, Ti-jiang; Zuo, Pan-li; Schmitt, Benjamin

2016-03-01

To determine the feasibility of using chemical exchange saturation transfer (CEST) imaging to measure creatine (Cr) metabolites with 3.0 T MR. Phantoms containing different concentrations of Cr under various pH conditions were studied with CEST sequence on 3.0 T MR imaging. CEST effect and Z spectra were analyzed. Cr exhibited significant CEST effect (± 1.8 ppm, F = 99.08, P < 0.001) on 3.0 T MR imaging, and positive correlation was found between the signal intensity and concentration of Cr (r = 0.963, P < 0.001). The CEST effect showed pH dependency of Cr (r = 0.41, P = 0.035). Creatine CEST imaging can be performed on 3.0 T MR imaging. Creatine concentrations and pH influence CEST effect.

Method for depleting BWRs using optimal control rod patterns

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taner, M.S.; Levine, S.H.; Hsiao, M.Y.

1991-01-01

Control rod (CR) programming is an essential core management activity for boiling water reactors (BWRs). After establishing a core reload design for a BWR, CR programming is performed to develop a sequence of exposure-dependent CR patterns that assure the safe and effective depletion of the core through a reactor cycle. A time-variant target power distribution approach has been assumed in this study. The authors have developed OCTOPUS to implement a new two-step method for designing semioptimal CR programs for BWRs. The optimization procedure of OCTOPUS is based on the method of approximation programming and uses the SIMULATE-E code for nucleonicsmore » calculations.« less

Preliminary Results on FeCrAl Alloys in the As-received and Welded State Designed to Have Enhanced Weldability and Radiation Tolerance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Field, Kevin G.; Gussev, Maxim N.; Hu, Xunxiang

2015-09-30

The present report summarizes and discusses the recent results on developing a modern, nuclear grade FeCrAl alloy designed to have enhanced radiation tolerance and weldability. The alloys used for these investigations are modern FeCrAl alloys based on a Fe-13Cr-5Al-2Mo-0.2Si-0.05Y alloy (in wt.%, designated C35M). Development efforts have focused on assessing the influence of chemistry and microstructure on the fabricability and performance of these newly developed alloys. Specific focus was made to assess the weldability, thermal stability, and radiation tolerance.

Quantitative CrAssphage PCR Assays for Human Fecal ...

EPA Pesticide Factsheets

Environmental waters are monitored for fecal pollution to protect public health and water resources. Traditionally, general fecal indicator bacteria are used; however, they cannot distinguish human fecal waste from pollution from other animals. Recently, a novel bacteriophage, crAssphage, was discovered by metagenomic data mining and reported to be abundant in and closely associated with human fecal waste. To confirm bioinformatic predictions, 384 primer sets were designed along the length of the crAssphage genome. Based upon initial screening, two novel crAssphage qPCR assays (CPQ_056 and CPQ_064) were designed and evaluated in reference fecal samples and water matrices. The assays exhibited high specificities (98.6%) when tested against a large animal fecal reference library and were highly abundant in raw sewage and sewage impacted water samples. In addition, CPQ_056 and CPQ_064 assay performance was compared to HF183/BacR287 and HumM2 methods in paired experiments. Findings confirm viral crAssphage qPCR assays perform at a similar level to well established bacterial human-associated fecal source identification technologies. These new viral based assays could become important water quality management and research tools. To inform the public.

Effects of 12-crown-4 ether on the electrochemical performance of CoO2 and TiS2 cathodes in Li polymer electrolyte cells

NASA Technical Reports Server (NTRS)

Nagasubramanian, G.; Attia, Alan I.; Halpert, G.

1992-01-01

The effect of adding 12-crown-4 ether (12Cr4) to the polyethylene oxide (PEO) electrolyte on the electrochemical properties of cells with Li(x)CoO2 or TiS2 as the cathode was investigated. The polymer electrolyte films were: (1) PEO, LiBF4; (2) PEO, LiBF4 with 12Cr4; (3) Li(x)CoO2, PEO, and LiBF4; and (4) Li(x)CoO2, PEO, LiBF4, and 12Cr4. It was found that, although 12Cr4 improved the cell performance over cells without 12Cr4 in the shallow c/d cycles (cyclic voltammetric behavior), it did not seem to prolong the active life of the cell. The cells with CoO2 as the cathode failed after a few c/d cycles, while similar cells with TiS2 did not fail even after 12 c/d cycles. The probable cause of failure in the case of CoO2 is ascribed to the instability of the CoO2 cathode.

Tungsten joining with copper alloy and its high heat load performance

NASA Astrophysics Data System (ADS)

Liu, Xiang; Lian, Youyun; Chen, Lei; Cheng, Zengkui; Chen, Jiming; Duan, Xuru; Song, Jioupeng; Yu, Yang

2014-12-01

W-CuCrZr joining technology by using low activation Cu-Mn filler metal was developed at Southwestern Institute of Physics (SWIP) for the manufacturing of divertor components of fusion experiment devices. In addition, a fast W coating technology by chemical vapor deposition (CVD) was also developed and CVD-W/CuCrZr and CVD-W/C mockups with a W coating thickness of 2 mm were prepared. In order to assess their high heat flux (HHF) performances, a 60 kW Electron-beam Material testing Scenario (EMS-60) equipped with a 150 keV electron beam welding gun was constructed at SWIP. Experimental results indicated that brazed W/CuCrZr mockups can withstand 8 MW/m2 heat flux for 1000 cycles without visible damages and CVD-W/CuCrZr mockups with W-Cu gradient interface can survive 1000 cycles under 11 MW/m2 heat flux. An ultrasonic inspection method for non-destructive tests (NDT) of brazed W/CuCrZr mockups was established and 2 mm defect can be detected. Infinite element analysis and heat load tests indicated that 5 mm defect had less noticeable influence on the heat transfer.

Development of mid-infrared solid state lasers for spaceborne lidar

NASA Technical Reports Server (NTRS)

Whitney, Donald A.; Kim, Kyong H.

1989-01-01

Laser performance of Ho(3+):Tm(3+):Cr(3+):YAG crystals was investigated under both Cr:GSAG laser and flashlamp pumping. A flashlamp pumped Cr:GSAG laser was built to simulate high power quasi-CW laser diode pumping of a 2.1 micrometer holmium laser. The 2.1 micrometer output laser energy exceeded more than 14 mJ, the highest value reported to date under laser pumping near 785 nm. This was obtained in a pulse length of nearly 650 microsec from a 3 x 3 mm Ho:Tm:Cr:YAG rod by using the flashlamp-pumped Cr:CSAG laser as a pumping source at the diode laser wavelength, 785 micrometers. In addition, Ho:Tm:Cr:YAG crystals with various Tm(3+) concentrations were evaluated for flashlamp-pumped normal mode and Q-switched 2.1 micrometer laser operations under a wide variety of experimental conditions in order to understand internal dynamic processes among the ions and to determine an optimum lasing condition. An increase of the laser slope efficiency was observed with the increase of the Tm(3+) concentration from 2.5 to 4.5 atomic percent. The thermal dependence of the laser performance was also investigated. Q-switched laser output energies corresponding to nearly 100 percent of the normal-mode laser energies were obtained in a strong single spike of 200 ns pulse length by optimizing the opening time of a lithium niobate Q-switch.

Modacrylic anion-exchange fibers for Cr(VI) removal from chromium-plating rinse water in batch and flow-through column experiments.

PubMed

Lee, Seung-Chan; Kang, Jin-Kyu; Sim, Eun-Hye; Choi, Nag-Choul; Kim, Song-Bae

2017-11-10

The aim of this study was to investigate Cr(VI) removal from chromium-plating rinse water using modacrylic anion-exchange fibers (KaracaronTM KC31). Batch experiments were performed with synthetic Cr(VI) solutions to characterize the KC31 fibers in Cr(VI) removal. Cr(VI) removal by the fibers was affected by solution pH; the Cr(VI) removal capacity was the highest at pH 2 and decreased gradually with a pH increase from 2 to 12. In regeneration and reuse experiments, the Cr(VI) removal capacity remained above 37.0 mg g -1 over five adsorption-desorption cycles, demonstrating that the fibers could be successfully regenerated with NaCl solution and reused. The maximum Cr(VI) removal capacity was determined to be 250.3 mg g -1 from the Langmuir model. In Fourier-transform infrared spectra, a Cr = O peak newly appeared at 897 cm -1 after Cr(VI) removal, whereas a Cr-O peak was detected at 772 cm -1 due to the association of Cr(VI) ions with ion-exchange sites. X-ray photoelectron spectroscopy analyses demonstrated that Cr(VI) was partially reduced to Cr(III) after the ion exchange on the surfaces of the fibers. Batch experiments with chromium-plating rinse water (Cr(VI) concentration = 1178.8 mg L -1 ) showed that the fibers had a Cr(VI) removal capacity of 28.1-186.4 mg g -1 under the given conditions (fiber dose = 1-10 g L -1 ). Column experiments (column length = 10 cm, inner diameter = 2.5 cm) were conducted to examine Cr(VI) removal from chromium-plating rinse water by the fibers under flow-through column conditions. The Cr(VI) removal capacities for the fibers at flow rates of 0.5 and 1.0 mL min -1 were 214.8 and 171.5 mg g -1 , respectively. This study demonstrates that KC31 fibers are effective in the removal of Cr(VI) ions from chromium-plating rinse water.

[Investigation of concentration levels of chromium(VI) in bottled mineral and spring waters by high performance ion chromatography technique with application of postcolumn reaction with 1,5-diphenylcarbazide and VIS detection].

PubMed

Swiecicka, Dorota; Garboś, Sławomir

2008-01-01

The aim of this work was optimization and validation of the method of determination of Cr(VI) existing in the form of chromate(VI) in mineral and spring waters by High Performance Ion Chromatography (HPIC) technique with application of postcolumn reaction with 1,5-diphenylcarbazide and VIS detection. Optimization of the method performed with the use of initial apparatus parameters and chromatographic conditions from the Method 218.6 allowed to lowering detection limit for Cr(VI) from 400 ng/l to 2 ng/l. Thanks to very low detection limit achieved it was possible to determine of Cr(VI) concentrations in 25 mineral and spring waters presented at Polish market. In the cases of four mineral and spring waters analyzed, determined Cr(VI) concentrations were below of quantification limit (< 4 ng/l) but simultaneously in another mineral and spring waters the concentrations of chromium(VI) were determined in the range of 5.6 - 1281 ng/l. The fact of existence of different Cr(VI) concentrations in investigated waters could be connected with secondary contamination of mineral and spring waters by chromium coming from metal installations and fittings. One should be underlined that even the highest determined concentration level of chromium(VI) was below of the maximum admissible concentration of total chromium presented in Polish Decree of Minister of Health from April 29th 2004. Therefore after taking into account determined in this work concentration of Cr(VI), the consumption of all waters analyzed in this study does not lead to essential human health risk.

Which total knee replacement implant should I pick? Correcting the pathology: the role of knee bearing designs.

PubMed

Berend, K R; Lombardi, A V; Adams, J B

2013-11-01

Debate has raged over whether a cruciate retaining (CR) or a posterior stabilised (PS) total knee replacement (TKR) provides a better range of movement (ROM) for patients. Various sub-sets of CR design are frequently lumped together when comparing outcomes. Additionally, multiple factors have been proven to influence the rate of manipulation under anaesthetic (MUA) following TKR. The purpose of this study was to determine whether different CR bearing insert designs provide better ROM or different MUA rates. All primary TKRs performed by two surgeons between March 2006 and March 2009 were reviewed and 2449 CR-TKRs were identified. The same CR femoral component, instrumentation, and tibial base plate were consistently used. In 1334 TKRs a CR tibial insert with 3° posterior slope and no posterior lip was used (CR-S). In 803 there was an insert with no slope and a small posterior lip (CR-L) and in 312 knees the posterior cruciate ligament (PCL) was either resected or lax and a deep-dish, anterior stabilised insert was used (CR-AS). More CR-AS inserts were used in patients with less pre-operative ROM and greater pre-operative tibiofemoral deformity and flexion contracture (p < 0.05). The mean improvement in ROM was highest for the CR-AS inserts (5.9° (-40° to 55°) vs CR-S 3.1° (-45° to 70°) vs CR-L 3.0° (-45° to 65°); p = 0.004). There was a significantly higher MUA rate with the CR-S and CR-L inserts than CR-AS (Pearson rank 6.51; p = 0.04). Despite sacrificing or not substituting for the PCL, ROM improvement was highest, and the MUA rate was lowest in TKRs with a deep-dish, anterior-stabilised insert. Substitution for the posterior cruciate ligament (PCL) in the form of a PS design may not be necessary even when the PCL is deficient.

Catalytic dehydrofluorination of 1,1,1,3,3-pentafluoropropane to 1,3,3,3-tetrafluoropropene over fluorinated NiO/Cr2O3 catalysts

NASA Astrophysics Data System (ADS)

Luo, Jian-Wei; Song, Jian-Dong; Jia, Wen-Zhi; Pu, Zhi-Ying; Lu, Ji-Qing; Luo, Meng-Fei

2018-03-01

Catalytic dehydrofluorination of 1,1,1,3,3-pentafluoropropane to 1,3,3,3-tetrafluoropropene was performed on a series of fluorinated NiO/Cr2O3 catalysts. The NiO/Cr2O3 catalysts were more active than the Cr2O3 because the new acid sites provided by NiF2 had higher turnover frequencies (9.43 × 10-3 - 12.08 × 10-3 s-1) than those on the Cr2O3 (4.55 × 10-3 s-1). Also, the NiO/Cr2O3 was more stable than the Cr2O3 due to its lower density of surface acid sites, which alleviated the coke deposition on the catalyst as evidenced by the Raman spectroscopic results. The kinetic results revealed that the15NiO/Cr2O3 had much lower activation energy (63.6 ± 4.5 kJ mol-1) than the Cr2O3 (127.6 ± 3.8 kJ mol-1). Accordingly, different reaction pathways on the two catalysts were proposed, which involved the cleavage of the Csbnd F and Csbnd H bonds on the surface acid and base sites, respectively.

Pulsed Laser Deposited Ferromagnetic Chromium Dioxide thin Films for Applications in Spintronics

NASA Astrophysics Data System (ADS)

Dwivedi, S.; Jadhav, J.; Sharma, H.; Biswas, S.

Stable rutile type tetragonal chromium dioxide (CrO2) thin films have been deposited on lattice-matched layers of TiO2 by KrF excimer laser based pulsed laser deposition (PLD) technique using Cr2O3 target. The TiO2 seed layer was deposited on oxidized Si substrates by the same PLD process followed by annealing at 1100 °C for 4 h. The lattice-matched interfacial layer is required for the stabilization of Cr (IV) phase in CrO2, since CrO2 behaves as a metastable compound under ambient conditions and readily converts into its stable phase of Cr (III) oxide, Cr2O3. Analyses with X-ray diffraction (XRD), Glancing-angle XRD (GIXRD), Raman spectroscopy and grazing-angle Fourier transform infra-red (FTIR) spectroscopy confirm the presence of tetragonal CrO2 phase in the as-deposited films. Microstructure and surface morphology in the films were studied with field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). Electrical and magnetic characterizations of the films were performed at room temperature. Such type of stable half-metallic CrO2 thin films with low field magnetoresistive switching behaviour are in demand for applications as diverse as spin-FETs, magnetic sensors, and magneto-optical devices.

Tribological Properties of HVOF-Sprayed TiB2-NiCr Coatings with Agglomerated Feedstocks

NASA Astrophysics Data System (ADS)

Zhao, Zichun; Li, Hui; Yang, Tianlong; Zhu, Hongbin

2018-04-01

Boride materials have drawn great attention in surface engineering field, owing to their high hardness and good wear resistance. In our previous work, a plasma-sprayed TiB2-based cermet coating was deposited, but the coating toughness was significantly influenced by the formation of a brittle ternary phase (Ni20Ti3B6) derived from the reaction between TiB2 and metal binder. In order to suppress such a reaction occurred in the high-temperature spraying process, the high-velocity oxygen-fuel spraying technique was applied to prepare the TiB2-NiCr coating. Emphasis was paid on the microstructure, the mechanical properties, and the sliding wearing performance of the coating. The result showed that the HVOF-sprayed coating mainly consisted of hard ceramic particles including TiB2, CrB, and the binder phase. No evidence of Ni20Ti3B6 phase was found in the coating. The mechanical properties of HVOF-sprayed TiB2-NiCr coating were comparable to the conventional Cr3C2-NiCr coating. The frictional coefficient of the TiB2-NiCr coating was lower than the Cr3C2-NiCr coating when sliding against a bearing steel ball.

Utility of Ochrobactrum anthropi YC152 in a Microbial Fuel Cell as an Early Warning Device for Hexavalent Chromium Determination.

PubMed

Wang, Guey-Horng; Cheng, Chiu-Yu; Liu, Man-Hai; Chen, Tzu-Yu; Hsieh, Min-Chi; Chung, Ying-Chien

2016-08-16

Fast hexavalent chromium (Cr(VI)) determination is important for environmental risk and health-related considerations. We used a microbial fuel cell-based biosensor inoculated with a facultatively anaerobic, Cr(VI)-reducing, and exoelectrogenic Ochrobactrum anthropi YC152 to determine the Cr(VI) concentration in water. The results indicated that O. anthropi YC152 exhibited high adaptability to pH, temperature, salinity, and water quality under anaerobic conditions. The stable performance of the microbial fuel cell (MFC)-based biosensor indicated its potential as a reliable biosensor system. The MFC voltage decreased as the Cr(VI) concentration in the MFC increased. Two satisfactory linear relationships were observed between the Cr(VI) concentration and voltage output for various Cr(VI) concentration ranges (0.0125-0.3 mg/L and 0.3-5 mg/L). The MFC biosensor is a simple device that can accurately measure Cr(VI) concentrations in drinking water, groundwater, and electroplating wastewater in 45 min with low deviations (<10%). The use of the biosensor can help in preventing the violation of effluent regulations and the maximum allowable concentration of Cr(VI) in water. Thus, the developed MFC biosensor has potential as an early warning detection device for Cr(VI) determination even if O. anthropi YC152 is a possible opportunistic pathogen.

Chromium Enhances Insulin Responsiveness via AMPK

PubMed Central

Hoffman, Nolan J.; Penque, Brent A.; Habegger, Kirk M.; Sealls, Whitney; Tackett, Lixuan; Elmendorf, Jeffrey S.

2014-01-01

Trivalent chromium (Cr3+) is known to improve glucose homeostasis. Cr3+ has been shown to improve plasma membrane-based aspects of glucose transporter GLUT4 regulation and increase activity of the cellular energy sensor 5′ AMP-activated protein kinase (AMPK). However, the mechanism(s) by which Cr3+ improves insulin responsiveness and whether AMPK mediates this action is not known. In this study we tested if Cr3+ protected against physiological hyperinsulinemia-induced plasma membrane cholesterol accumulation, cortical filamentous actin (F-actin) loss and insulin resistance in L6 skeletal muscle myotubes. In addition, we performed mechanistic studies to test our hypothesis that AMPK mediates the effects of Cr3+ on GLUT4 and glucose transport regulation. Hyperinsulinemia-induced insulin-resistant L6 myotubes displayed excess membrane cholesterol and diminished cortical F-actin essential for effective glucose transport regulation. These membrane and cytoskeletal abnormalities were associated with defects in insulin-stimulated GLUT4 translocation and glucose transport. Supplementing the culture medium with pharmacologically relevant doses of Cr3+ in the picolinate form (CrPic) protected against membrane cholesterol accumulation, F-actin loss, GLUT4 dysregulation and glucose transport dysfunction. Insulin signaling was neither impaired by hyperinsulinemic conditions nor enhanced by CrPic, whereas CrPic increased AMPK signaling. Mechanistically, siRNA-mediated depletion of AMPK abolished the protective effects of CrPic against GLUT4 and glucose transport dysregulation. Together these findings suggest that the micronutrient Cr3+, via increasing AMPK activity, positively impacts skeletal muscle cell insulin sensitivity and glucose transport regulation. PMID:24725432

Synthesis of Cr3+-doped TiO2 nanoparticles: characterization and evaluation of their visible photocatalytic performance and stability.

PubMed

Mendiola-Alvarez, Sandra Yadira; Guzmán-Mar, Jorge Luis; Turnes-Palomino, Gemma; Maya-Alejandro, Fernando; Caballero-Quintero, Adolfo; Hernández-Ramírez, Aracely; Hinojosa-Reyes, Laura

2017-09-28

Cr 3+ -doped TiO 2 nanoparticles (Ti-Cr) were synthesized by microwave-assisted sol-gel method. The Ti-Cr catalyst was characterized by X-ray diffraction, ultraviolet-visible diffuse reflectance spectroscopy, N 2 adsorption-desorption analysis, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy (XPS) and zetametry. The anatase mesoporous Ti-Cr material exhibited a specific surface area of 54.5 m 2 /g. XPS analysis confirmed the proper substitution of Ti 4+ cations by Cr 3+ cations in the TiO 2 matrix. The particle size was of average size of 17 nm for the undoped TiO 2 but only 9.5 nm for Ti-Cr. The Cr atoms promoted the formation of hydroxyl radicals and modified the surface adsorptive properties of TiO 2 due to the increase in surface acidity of the material. The photocatalytic evaluation demonstrated that the Ti-Cr catalyst completely degraded (4-chloro-2-methylphenoxy) acetic acid under visible light irradiation, while undoped TiO 2 and P25 allowed 45.7% and 31.1%, respectively. The rate of degradation remained 52% after three cycles of catalyst reuse. The higher visible light photocatalytic activity of Ti-Cr was attributed to the beneficial effect of Cr 3+ ions on the TiO 2 surface creating defects within the TiO 2 crystal lattice, which can act as charge-trapping sites, reducing the electron-hole recombination process.

Adaptive waveform optimization design for target detection in cognitive radar

NASA Astrophysics Data System (ADS)

Zhang, Xiaowen; Wang, Kaizhi; Liu, Xingzhao

2017-01-01

The problem of adaptive waveform design for target detection in cognitive radar (CR) is investigated. This problem is analyzed in signal-dependent interference, as well as additive channel noise for extended target with unknown target impulse response (TIR). In order to estimate the TIR accurately, the Kalman filter is used in target tracking. In each Kalman filtering iteration, a flexible online waveform spectrum optimization design taking both detection and range resolution into account is modeled in Fourier domain. Unlike existing CR waveform, the proposed waveform can be simultaneously updated according to the environment information fed back by receiver and radar performance demands. Moreover, the influence of waveform spectral phase to radar performance is analyzed. Simulation results demonstrate that CR with the proposed waveform performs better than a traditional radar system with a fixed waveform and offers more flexibility and suitability. In addition, waveform spectral phase will not influence tracking, detection, and range resolution performance but will greatly influence waveform forming speed and peak-to-average power ratio.

7 Tesla proton magnetic resonance spectroscopic imaging in adult X-linked adrenoleukodystrophy

PubMed Central

Ratai, Eva; Kok, Trina; Wiggins, Christopher; Wiggins, Graham; Grant, Ellen; Gagoski, Borjan; O'Neill, Gilmore; Adalsteinsson, Elfar; Eichler, Florian

2010-01-01

Background Adult patients with X-linked adrenoleukodystrophy (X-ALD) remain at risk for progressive neurological deterioration. Phenotypes vary in their pathology, ranging from axonal degeneration to inflammatory demyelination. The severity of symptoms is poorly explained by conventional imaging. Objective To test the hypothesis that neurochemistry in normal appearing brain differs among adult phenotypes of X-ALD, and that neurochemical changes correlate with the severity of symptoms. Patients and Methods Using a 7 Tesla scanner we performed structural and proton MRSI in 13 adult patients with X-ALD, including 4 patients with adult cerebral ALD (ACALD), 5 with adrenomyeloneuropathy (AMN) and 4 female heterozygotes. Studies were also performed in nine healthy controls. Results Among adult X-ALD phenotypes, MI/Cr was 46% higher and Cho/Cr 21% higher in normal appearing white matter of ACALD compared to AMN (p < 0.05). Both NAA/Cr and Glu/Cr ratios were lower in AMN patients (p = 0.028 and p = 0.036, respectively) than in controls. There were no significant differences between AMN and female heterozygotes. In cortex, ACALD patients had lower values of NAA/Cr compared to female heterozygotes and controls (p = 0.022). The global MI/Cr ratio demonstrated a significant association with the EDSS (Spearman ρ = 0.66, p = 0.039). Conclusion 7 Tesla proton MRSI reveals differences in the neurochemistry of ACALD but is unable to distinguish AMN from female heterozygotes. MI/Cr correlates with the severity of the symptoms and may be a meaningful biomarker in adult X-ALD. PMID:19001168

Using precipitated Cr on the surface of Cu-Cr alloy powders as catalyst synthesizing CNTs/Cu composite powders by water-assisted CVD

NASA Astrophysics Data System (ADS)

Zhou, Honglei; Liu, Ping; Chen, Xiaohong; Bi, Liming; Zhang, Ke; Liu, Xinkuan; Li, Wei; Ma, Fengcang

2018-02-01

Given that the conventional catalyst is easily soluble in the matrix to result in the poor performance of the CNTs/Cu composite materials, the Cr nano-particles precipitated on the surface of Cu-Cr particles are first used as catalysts to prepare the CNTs/Cu composite powders by means of water-assisted chemical vapor deposition in situ synthesis. The results show that the morphological difference of the precipitated Cr nano-particle is obvious with the change of solution and aging treatment, and the morphology, length and diameter of the synthetic CNTs are also different. The catalyst of Cr nano-particle has the best morphology and the synthesized CNTs had a good wettability with Cu particles when the Cu-Cr composite powders was solution-treated at 1023 K for 60 min and then was aged at 723 K for 120 min. The length, diameter, yield and purity of the synthesized CNTs can be also affected by the moisture content in the reaction gas. It is the most suitable for the growth of CNTs when the moisture content is 0.4%, and the high purity and defect-free CNTs with the smooth pipe wall, a diameter of 20 ˜ 30 nm and a length of up to 1800 nm can be obtained. The yield of CNTs with the moisture content of 0.4% reached to 138%, which was increased by 119% to compare with that without moisture. In this paper, a feasible technology was offered for the preparation of high performance CNTs/Cu composites.

Treatment of Cr(VI)-containing wastewaters with exopolysaccharide-producing cyanobacteria in pilot flow through and batch systems.

PubMed

Colica, Giovanni; Mecarozzi, Pier Cesare; De Philippis, Roberto

2010-08-01

Seven exopolysaccharide-producing cyanobacteria were tested with regard to their capability to remove Cr(VI) from the wastewater of a plating industry. The cyanobacterium which showed, under lab conditions, the most promising features with regard to both Cr(VI) removal (about 12 mg of Cr(VI) removed per gram of dry biomass) and growth characteristics (highest growth rate and simplest culture medium) was Nostoc PCC7936. Furthermore, in lab experiments, it was also found that a HCl pretreatment is essential to abate the concentration of Cr(VI) in solution and that the viability of the biomass is not necessary. Subsequently, three pilot devices were tested, one batch (a dialysis cell) and two flow-through systems (a filter press and a column filled with quartz grain). The best performances were obtained with the filter press, where it was observed a sharp decrease in the concentration of Cr(VI), partly due to the adsorption of the metal by the biomass (about 50%) and partly due to its reduction to Cr(III). The results are discussed in terms of the role played by the different components (biomass and polysaccharide) of the cyanobacterial cultures in the removal of Cr(VI).

Removal of Cr(VI) ions by sewage sludge compost biomass from aqueous solutions: Reduction to Cr(III) and biosorption

NASA Astrophysics Data System (ADS)

Chen, Huixia; Dou, Junfeng; Xu, Hongbin

2017-12-01

Sewage sludge compost biomass was used as a novel biosorbent to remove hexavalent chromium from water. Surface area analysis, scanning electron microscopy, fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and point zero charge was applied to study the microstructure, compositions and chemical bonding states of the biomass adsorbent. Effects of contact time, biomass dosage, agitation speed, pH, the initial concentration of Cr(VI) and Cr(Ⅲ) on its adsorption removal were also performed in the batch experiments. A model describing adsorption, desorption and reduction phenomena during the sorption process has been referenced to model Cr(VI) sorption onto sewage sludge compost biomass. The result of characterization test shows that adsorption of Cr(VI) onto sewage sludge compost biomass followed by the partial reduction to Cr(Ⅲ) by biomass groups such as hydroxyl, carboxyl, and amino groups. The absorption kinetics model in the description of adsorption-coupled reduction of Cr(VI) fits successfully the kinetic data obtained at different temperatures and describes the kinetics profile of total, hexavalent and trivalent chromium. The study shows that sewage sludge compost biomass could be used as a potential biosorbent for removal of hexavalent chromium from wastewaters.

Effect of pressure on the magnetic properties of TM3[Cr(CN)6]2·12H2O

NASA Astrophysics Data System (ADS)

Zentková, M.; Arnold, Z.; Kamarád, J.; Kavecanský, V.; Lukácová, M.; Mat'aš, S.; Mihalik, M.; Mitróová, Z.; Zentko, A.

2007-07-01

We present the results of magnetization and AC susceptibility measurements performed on ferrimagnetic Mn32+[CrIII(CN)6]2·12H2O and ferromagnetic Ni32+[CrIII(CN)6]2·12H2O systems under pressures up to 0.9 GPa in a commercial SQUID magnetometer. The magnetization process is affected by pressure: magnetization saturates at higher magnetic field, saturated magnetization μs of Ni3[Cr(CN)6]2 is reduced and almost unaffected for Mn3[Cr(CN)6]2 at low temperatures. The Curie temperature TC of Mn3[Cr(CN)6]2 increases with the applied pressure, ΔTC/Δp = 25.5 K GPa-1, due to a strengthened super-exchange antiferromagnetic interaction JAF, but it is not affected significantly in the case of Ni3[Cr(CN)6]2 with a dominant ferromagnetic JF super-exchange interaction. The increase in the JAF interaction is attributed to the enhanced value of the single electron overlapping integral S and the energy gap Δ of the mixed molecular orbitals t2g (Mn2+) and t2g (CrIII) induced by pressure.

Dietary Supplementation with Chromium Picolinate Influences Serum Glucose and Immune Response of Brown-Egg Laying Hens.

PubMed

Zhang, Shumin; Sun, Xiaoming; Liao, Xiudong; Lu, Lin; Zhang, Liyang; Ma, Qiugang; Luo, Xugang

2018-01-29

To investigate the effect of chromium picolinate (CrPic) on egg production performance, egg quality, blood indices, and immune function of laying hens, 270 23-week-old Beijing Red brown-egg laying hens were randomly assigned to one of three treatments with six replicates of 15 birds per replicate for each treatment in a completely randomized design. Laying hens were fed a Cr-unsupplemented corn-soybean meal basal diet (control, containing 0.45 mg Cr/kg by analysis) or the basal diet supplemented with 0.4 or 0.6 mg Cr/kg from CrPic for 10 weeks. Laying hens fed diets supplemented with CrPic had a lower (P < 0.05) serum glucose (GLU) concentration and higher (P < 0.03) serum antibody titer against Newcastle disease than those fed the control diet at 33 weeks of age. However, supplemental CrPic had no effect (P > 0.05) on egg production and egg quality of brown-egg laying hens from 24 to 33 weeks of age. The results from this study indicated that supplemental CrPic decreased serum GLU and enhanced the immune function of brown-egg laying hens.

An in situ study of growth of Lemongrass Cymbopogon flexuosus (Nees ex Steud.) W. Watson on varying concentration of Chromium (Cr+6) on soil and its bioaccumulation: Perspectives on phytoremediation potential and phytostabilisation of chromium toxicity.

PubMed

Patra, Deepak Kumar; Pradhan, Chinmay; Patra, Hemanta Kumar

2018-02-01

Chromium (Cr) contamination in soil is a growing concern in sustainable agricultural production and food safety. Remediation of Cr from contaminated soils is a challenging task which may not only help in sustaining agriculture but also in minimizing adverse environmental impacts. Pot culture experiments were performed with the application of varied concentration of Cr +6 to assess the Chromium accumulation potential of Lemongrass and to study the impact of toxic concentration of Cr +6 on morphological, physiological and biochemical parameters of the plant. The results showed an increasing accumulation trend of Chromium with increasing Chromium concentrations in both root and shoot of 60 days old Lemongrass plants, while the protein and chlorophyll contents decreased. Similarly, accumulation of Cr increased the levels of proline and antioxidant enzymes indicating the enhanced damage control activity. The potentiality of the plant with the capacity to accumulate and stabilize Cr compound in Cr contaminated soil by phytoremediation process has been explored in the present investigation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Microstructure and Mechanical Properties of Cr-SiC Particles-Reinforced Fe-Based Alloy Coating

NASA Astrophysics Data System (ADS)

Wang, Fu-cheng; Du, Xiao-dong; Zhan, Ma-ji; Lang, Jing-wei; Zhou, Dan; Liu, Guang-fu; Shen, Jian

2015-12-01

In this study, SiC particles were first coated with Cr to form a layer that can protect the SiC particles from dissolution in the molten pool. Then, the Cr-SiC powder was injected into the tail of molten pool during plasma-transferred arc welding process (PTAW), where the temperature was relatively low, to prepare Cr-SiC particles reinforced Fe-based alloy coating. The microstructure and phase composition of the powder and surface coatings were analyzed, and the element distribution and hardness at the interfacial region were also evaluated. The protective layer consists of Cr3Si, Cr7C3, and Cr23C6, which play an important role in the microstructure and mechanical properties. The protective layer is dissolved in the molten pool forming a flocculent region and a transition region between the SiC particles and the matrix. The tribological performance of the coating was also assessed using a ring-block sliding wear tester with GGr15 grinding ring under 490 and 980 N load. Cr-SiC particles-reinforced coating has a lower wear rate than the unreinforced coating.

Tribological Behavior of Al-Cr Coating Obtained by Dgpsm and IIP Composite Technology

NASA Astrophysics Data System (ADS)

Luo, Xixi; Yao, Zhengjun; Zhang, Pingze; Zhou, Keyin; Chen, Yu; Tao, Xuewei

An Al-Cr composite alloyed layer composed of an Al enriched layer, a Cr enriched layer and a transition layer from the surface to the bulk along the cross-section was deposited on a 45# steel substrate by composite technology, where Cr was deposited using double glow plasma surface metallurgy (DGPSM), and Al was then implanted by ion implantation (IIP) to achieve higher micro-hardness and excellent abrasive resistance. The composite alloyed layer is approximately 5μm, and as metallurgical adherence to the substrate. The phases are Al8Cr5, Fe2AlCr, Cr23C6, Cr (Al) and Fe (Cr, Al) solid solution. The wear resistance tests were performed under various rotational speed (i.e. 280, 560 and 840r/min) with silicon nitride balls as the counterface material at ambient temperature. The Al-Cr composite alloyed layer exhibits excellent wear resistance when the speed is 280r/min with a friction coefficient as low as 0.3, which is attributed to Al8Cr5 in the Al implanted layer that withstands abrasive wear. Better wear resistance (friction coefficient: 0.254) at 560r/min is resulted from the formation of a high micro-hardness zone, and an oxidation layer with lubrication capacity. In addition, the composite alloyed layer suffers severe oxidative wear and adhesive wear at 840r/min due to the increment of the frictional heating. When compared to the 45# steel substrate, the enhanced wear resistance of the Al-Cr composite alloyed layer demonstrates the viable method developed in this work.

Resting-state global functional connectivity as a biomarker of cognitive reserve in mild cognitive impairment.

PubMed

Franzmeier, N; Caballero, M Á Araque; Taylor, A N W; Simon-Vermot, L; Buerger, K; Ertl-Wagner, B; Mueller, C; Catak, C; Janowitz, D; Baykara, E; Gesierich, B; Duering, M; Ewers, M

2017-04-01

Cognitive reserve (CR) shows protective effects in Alzheimer's disease (AD) and reduces the risk of dementia. Despite the clinical significance of CR, a clinically useful diagnostic biomarker of brain changes underlying CR in AD is not available yet. Our aim was to develop a fully-automated approach applied to fMRI to produce a biomarker associated with CR in subjects at increased risk of AD. We computed resting-state global functional connectivity (GFC), i.e. the average connectivity strength, for each voxel within the cognitive control network, which may sustain CR due to its central role in higher cognitive function. In a training sample including 43 mild cognitive impairment (MCI) subjects and 24 healthy controls (HC), we found that MCI subjects with high CR (> median of years of education, CR+) showed increased frequency of high GFC values compared to MCI-CR- and HC. A summary index capturing such a surplus frequency of high GFC was computed (called GFC reserve (GFC-R) index). GFC-R discriminated MCI-CR+ vs. MCI-CR-, with the area under the ROC = 0.84. Cross-validation in an independently recruited test sample of 23 MCI subjects showed that higher levels of the GFC-R index predicted higher years of education and an alternative questionnaire-based proxy of CR, controlled for memory performance, gray matter of the cognitive control network, white matter hyperintensities, age, and gender. In conclusion, the GFC-R index that captures GFC changes within the cognitive control network provides a biomarker candidate of functional brain changes of CR in patients at increased risk of AD.

The effect of epileptic seizures on proton MRS visible neurochemical concentrations.

PubMed

Simister, Robert J; McLean, Mary A; Salmenpera, Tuuli M; Barker, Gareth J; Duncan, John S

2008-09-01

To investigate post-ictal changes in cerebral metabolites. We performed a longitudinal quantitative proton magnetic resonance spectroscopy (MRS) study in 10 patients with epilepsy and 10 control subjects. The patients were studied on two occasions: immediately following a seizure, and on a second occasion at least 7h after the most recent seizure. Each study measured N-acetyl aspartate plus N-acetyl aspartyl glutamate (NAAt), Creatine plus phosphocreatine (Cr), Choline containing compounds (Cho) and glutamate plus glutamine (GLX) concentrations using a short-echo time sequence (TE=30ms), and NAAt, Cr and lactate using a second sequence with longer echo time (TE=144ms). The control group was studied on two occasions using the same sequences. No inter-scan differences were observed for the control group. NAAt and NAAt/Cr levels were lower in the patient group at both measured TEs but did not change significantly between studies. The ratio of Cr at TE 144ms to TE 30ms (Cr(144)/Cr(30)) and GLX/Cr were higher and Cho lower in the post-ictal scan compared to the inter-ictal study. Change in Cr(144)/Cr(30) and NAAt(144)/Cr(144) correlated with the post-ictal interval. Lactate measurement at longer TE was not informative. Proton MRS is sensitive to metabolite changes following epileptic seizures within the immediate post-ictal period. The ratio Cr(144)/Cr(30) is the most sensitive measure of metabolic disturbance and is highest in the post-ictal period but appears to normalise within 2h of the most recent seizure.

Differences in uptake and translocation of hexavalent and trivalent chromium by two species of willows.

PubMed

Yu, Xiao-Zhang; Gu, Ji-Dong; Xing, Li-Qun

2008-11-01

Uptake and translocation of chromium (Cr) by two willow species was investigated. Intact pre-rooted weeping willows (Salix babylonica L.) and hankow willows (Salix matsudana Koidz) were grown hydroponically and spiked with hexavalent chromium [Cr (VI)] or trivalent chromium [Cr (III)] at 25.0 +/- 0.5 degrees C for 120 h. Removal of leaves was also performed as a treatment to quantify the effect of transpiration on uptake and translocation of either of the Cr species. Although the two willow species were able to eliminate Cr (VI) and Cr (III) from the hydroponic solution, significant differences in the removal rate for both chemical species were observed between the two willows (p < 0.05): faster removal rate for Cr (III) than Cr (VI) was detected in both willow species; hankow willows showed higher removal potential for both chemical species than weeping willows. Remarkable decreases in the removal rates for both Cr species were detected in the willows with leaves removed (p < 0.05). The results from the treatments spiked with Cr (VI) also revealed that Cr was more mobile in plant materials of hankow willows than that in weeping willows (p < 0.01), while higher translocation efficiency of Cr was observed in weeping willows than hankow willows for the Cr (III) treated (p < 0.01). However, a convincing decrease in the translocation efficiency due to the removal of leaves was only observed in the treatments spiked with Cr (VI) (p < 0.05). Substantial differences existed in the distribution of Cr species in plant materials after exposure of either of the chemical forms: roots and lower stems were the major sites for accumulation in weeping willows exposed to Cr (VI) and Cr (III), respectively; in contrast roots were the only sink in hankow willows exposed to both chemical species. The capacity of willows to assimilate both Cr species was also evaluated using detached leaves and roots of both willow species in sealed glass vessels in vivo. The results indicated that detached roots showed a more remarkable capacity to remove Cr (III) from the hydroponic solution than Cr (VI) (p < 0.01). Although detached leaves of both willow species were able to efficiently eliminate Cr (III), neither of them reduced the concentration of Cr (VI) in the solution. The results suggests that different mechanisms for uptake, assimilation and translocation of Cr (VI) and Cr (III) exist in different willow species and phytoremediation of Cr should consider this factor for the proposed target effectively.

Failure Mechanisms of the Protective Coatings for the Hot Stamping Applications

NASA Astrophysics Data System (ADS)

Zhao, Chen

In the present study, four different nitriding techniques were carried on the ductile irons NAAMS-D6510 and cast steels NAAMS-S0050A, which are widely used stamping die materials; duplex treatments (PVD CrN coating+nitriding) were carried on H13 steels, which are common inserts for the hot stamping dies. Inclined impact-sliding wear tests were performed on the nitriding cases under simulated stamping conditions. Surface profilometer, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were used to investigate the wear and failure mechanisms of the protective coatings. It was found that the nitrided ductile iron samples performed better than the nitrided cast steel specimens. High temperature inclined impact-sliding wear tests were carried out on the CrN coatings. It was found that the coating performed better at elevated temperature. XPS analysis indicated the top surface layer (about 3-4nm) of the coating was oxidized at 400 °C and formed a Cr2O3 protective film. The in-situ formation of the thin Cr2O3 protective layer likely led to the change of wear mechanisms from severe adhesive failure to mild abrasive wear.

Burbank performs Part 1 of the WRS-1 Repair

NASA Image and Video Library

2012-03-08

ISS030-E-128752 (8 March 2012) --- NASA astronaut Dan Burbank, Expedition 30 commander, performs part one of the Water Recovery System-1 (WRS-1) repair in the Tranquility node of the International Space Station. Burbank removed and replaced the failed Catalytic Reactor (CR), and installed a temporary filter kit between the new CR and the Microbial Check Valve (MCV) to support a system flush of the new Orbital Replacement Unit (ORU).

The effect of DEB powder processing on thermal cell performance

NASA Astrophysics Data System (ADS)

Szwarc, R.; Walton, R. D.

During the last twenty years, the system Ca/LiCl-KCl-CaCrO4/Fe has provided the basis for thermal batteries designed for military applications. In connection with greater performance demands, investigations are being conducted concerning the effect of catholyte processing on thermal cell performance. The catholyte layer is composed of three components including the depolarizer (D), CaCrO4, the electrolyte (E), LiCl-KCl eutectic, and the binder (B), finely divided SiO2. The catholyte layer or DEB pellets are produced by blending these components, fusing, pulverizing the cake, and hydrostatically pressing the powder into pellets. A description is given of ten powders which were prepared for the reported study. It was found that the procedure used in powder processing affects the capacity, but not its voltage. Increasing the prebake temperature for CaCrO4 from 400 to 600 C resulted in an increase in capacity.

Oxidation behaviour of silicon-free tungsten alloys for use as the first wall material

NASA Astrophysics Data System (ADS)

Koch, F.; Brinkmann, J.; Lindig, S.; Mishra, T. P.; Linsmeier, Ch

2011-12-01

The use of self-passivating tungsten alloys as armour material of the first wall of a fusion power reactor may be advantageous concerning safety issues. In earlier studies good performance of the system W-Cr-Si was demonstrated. Thin films of such alloys showed a strongly reduced oxidation rate compared to pure tungsten. However, the formation of brittle tungsten silicides may be disadvantageous for the powder metallurgical production of bulk W-Cr-Si alloys if a good workability is needed. This paper shows the results of screening tests to identify suitable silicon-free alloys with distinguished self-passivation and a potentially good workability. Of all the tested systems W-Cr-Ti alloys showed the most promising results. The oxidation rate was even lower than the one of W-Cr-Si alloys, the reduction factor was about four orders of magnitude compared to pure tungsten. This performance could be conserved even if the content of alloying elements was reduced.

Excimer laser decoating of chromium titanium aluminium nitride to facilitate re-use of cutting tools

NASA Astrophysics Data System (ADS)

Sundar, M.; Whitehead, D.; Mativenga, P. T.; Li, L.; Cooke, K. E.

2009-11-01

This work reports on the technical feasibility and establishment of a process window for removing chromium titanium aluminium nitride (CrTiAlN) coating from steel substrates by laser irradiation. CrTiAlN coating has high hardness and oxidation resistance, with applications for use with cutting tools. The motivation for removing such coatings is to facilitate re-use of tooling by enabling regrinding or reshaping of a worn tool and hence promote sustainable material usage. In this work, laser decoating was performed using an excimer laser. The effect of laser fluence, number of pulses, frequency, scanning speed and laser beam overlap on the decoating performance was investigated in detail. The minimum threshold laser fluence for removing the CrTiAlN coating was lower than that of the steel substrate and this factor is beneficial in controlling the decoating process. Successful laser removal of CrTiAlN coating without noticeable damage to the steel substrate was demonstrated.

Reduced N-acetylaspartate to creatine ratio in the posterior cingulate correlates with cognition in Alzheimer's disease following four months of rivastigmine treatment.

PubMed

Penner, Jacob; Wells, Jennie L; Borrie, Michael J; Woolmore-Goodwin, Sarah M; Bartha, Robert

2015-01-01

To determine whether 4 months of rivastigmine treatment would result in metabolic changes and whether metabolic changes correlate with changes in cognition in people with Alzheimer's disease (AD). Magnetic resonance spectra were acquired from the posterior cingulate cortex of subjects with AD at 3 T. Magnetic resonance imaging scans and cognitive tests were performed before and 4 months after the beginning of the treatment. Metabolite concentrations were quantified and used to calculate the metabolite ratios. On average, the N-acetylaspartate/creatine (NAA/Cr) ratio decreased by 12.7% following 4 months of rivastigmine treatment, but changes in the NAA/Cr ratio correlated positively with changes in Mini-Mental State Examination scores. This positive correlation between changes in NAA/Cr and changes in cognitive performance suggests that the NAA/Cr ratio could be an objective indicator of a response to rivastigmine treatment. © 2014 S. Karger AG, Basel

DEVELOPMENT OF CRASSPHAGE-BASED QPCR ASSAYS ...

EPA Pesticide Factsheets

A newly discovered bacteriophage, “crAssphage”, is predicted to be both highlyabundant and predominantly human-associated, both ideal characteristics for a human-specific fecal indicator. A total of 384 end-point PCR primers were designed along the length of the crAssphage genome, eliminating regions suspected to be hypervariable or react with other animal sources. The primer pairs were rigorously tested in three rounds of screening for specificity, geographic variability, limit of detection, and environmental water performance. The two best performing assays, crAss056 and crAss064, were adapted to a qPCR platform and exhibited a specificity of 98.0% and 98.9%, respectively. The markers’ abundance was compared with two bacterial based assays and were found at concentrations at or above the bacterial based assays in wastewater influent and impacted environmental waters. This poster will present the methodology of the novel marker development and the potential uses for this technology in maintaining sustainable waterways in the future. To inform the public.

Relationships between astrogliosis and 1H MR spectroscopic measures of brain choline/creatine and myo-inositol/creatine in a primate model.

PubMed

Kim, John P; Lentz, Margaret R; Westmoreland, Susan V; Greco, Jane B; Ratai, Eva M; Halpern, Elkan; Lackner, Andrew A; Masliah, Eliezer; González, R Gilberto

2005-04-01

In vivo 1H MR spectroscopy demonstrates elevated choline (Cho)/creatine (Cr) and myo-inositol (MI)/Cr in many neurologic diseases that has been ascribed to gliosis. We tested the hypotheses that in vivo Cho/Cr and/or MI/Cr levels are correlated with glial fibrillary acidic protein (GFAP) immunostains and that the changes are water-soluble metabolites. We performed postmortem 1H MR spectroscopy and GFAP immunohistochemistry in brains from seven rhesus macaques acutely infected with simian immunodeficiency virus (SIV) and in four controls and compared the findings with previous in vivo MR spectroscopic results. Changes in neuropathologic and MR spectroscopic markers after infection and relationships among plasma viral load, GFAP immunostaining results, and ex vivo and in vivo MR spectroscopic measures were statistically evaluated. On GFAP immunostaining and in vivo MR spectroscopy, GFAP, Cho/Cr and MI/Cr were highest near the time of peak plasma viral load at 11 days postinfection (dpi). Immunostains returned to baseline by 14 dpi, whereas Cho/Cr and MI/Cr had different time courses, with the former dropping below baseline and the latter remaining elevated. Viral load and immunostains were significantly correlated. No correlation was found between ex vivo Cho/Cr or MI/Cr and viral load or between metabolite ratios from in vivo and ex vivo MR spectroscopy. In acute SIV infection, plasma viral load was significantly correlated with brain GFAP immunostains and in vivo 1H MR spectroscopic Cho/Cr. In vivo changes in Cho/Cr and MI/Cr were principally due to contributions other than those of low-molecular-weight water-soluble metabolites.

Electrochemical sensing and biosensing platform based on chemically reduced graphene oxide.

PubMed

Zhou, Ming; Zhai, Yueming; Dong, Shaojun

2009-07-15

In this paper, the characterization and application of a chemically reduced graphene oxide modified glassy carbon (CR-GO/GC) electrode, a novel electrode system, for the preparation of electrochemical sensing and biosensing platform are proposed. Different kinds of important inorganic and organic electroactive compounds (i.e., probe molecule (potassium ferricyanide), free bases of DNA (guanine (G), adenine (A), thymine (T), and cytosine (C)), oxidase/dehydrogenase-related molecules (hydrogen peroxide (H2O2)/beta-nicotinamide adenine dinucleotide (NADH)), neurotransmitters (dopamine (DA)), and other biological molecules (ascorbic acid (AA), uric acid (UA), and acetaminophen (APAP)) were employed to study their electrochemical responses at the CR-GO/GC electrode, which shows more favorable electron transfer kinetics than graphite modified glassy carbon (graphite/GC) and glassy carbon (GC) electrodes. The greatly enhanced electrochemical reactivity of the four free bases of DNA at the CR-GO/GC electrode compared with that at graphite/GC and GC electrodes makes the CR-GO/GC electrode a better choice for the electrochemical biosensing of four DNA bases in both the single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) at physiological pH without a prehydrolysis step. This allows us to detect a single-nucleotide polymorphism (SNP) site for short oligomers with a particular sequence at the CR-GO/GC electrode without any hybridization or labeling processes in this work, suggesting the potential applications of CR-GO in the label-free electrochemical detection of DNA hybridization or DNA damage for further research. Based on the greatly enhanced electrochemical reactivity of H2O2 and NADH at the CR-GO/GC electrode, CR-GO/GC electrode-based bioelectrodes (in connection with glucose oxidase (GOD) and alcohol dehydrogenase (ADH)) show a better analytical performance for the detection of glucose and ethanol compared with graphite/GC- or GC-based bioelectrodes. By comparing the electrochemical performance of CR-GO with that of the conventional graphite and GC, we reveal that CR-GO with the nature of a single sheet showing favorable electrochemical activity should be a kind of more robust and advanced carbon electrode material which may hold great promise for electrochemical sensors and biosensors design.

Robust Strategy for Crafting Li5Cr7Ti6O25@CeO2 Composites as High-Performance Anode Material for Lithium-Ion Battery.

PubMed

Mei, Jie; Yi, Ting-Feng; Li, Xin-Yuan; Zhu, Yan-Rong; Xie, Ying; Zhang, Chao-Feng

2017-07-19

A facile strategy was developed to prepare Li 5 Cr 7 Ti 6 O 25 @CeO 2 composites as a high-performance anode material. X-ray diffraction (XRD) and Rietveld refinement results show that the CeO 2 coating does not alter the structure of Li 5 Cr 7 Ti 6 O 25 but increases the lattice parameter. Scanning electron microscopy (SEM) indicates that all samples have similar morphologies with a homogeneous particle distribution in the range of 100-500 nm. Energy-dispersive spectroscopy (EDS) mapping and high-resolution transmission electron microscopy (HRTEM) prove that CeO 2 layer successfully formed a coating layer on a surface of Li 5 Cr 7 Ti 6 O 25 particles and supplied a good conductive connection between the Li 5 Cr 7 Ti 6 O 25 particles. The electrochemical characterization reveals that Li 5 Cr 7 Ti 6 O 25 @CeO 2 (3 wt %) electrode shows the highest reversibility of the insertion and deinsertion behavior of Li ion, the smallest electrochemical polarization, the best lithium-ion mobility among all electrodes, and a better electrochemical activity than the pristine one. Therefore, Li 5 Cr 7 Ti 6 O 25 @CeO 2 (3 wt %) electrode indicates the highest delithiation and lithiation capacities at each rate. At 5 C charge-discharge rate, the pristine Li 5 Cr 7 Ti 6 O 25 only delivers an initial delithiation capacity of ∼94.7 mAh g -1 , and the delithiation capacity merely achieves 87.4 mAh g -1 even after 100 cycles. However, Li 5 Cr 7 Ti 6 O 25 @CeO 2 (3 wt %) delivers an initial delithiation capacity of 107.5 mAh·g -1 , and the delithiation capacity also reaches 100.5 mAh g -1 even after 100 cycles. The cerium dioxide modification is a direct and efficient approach to improve the delithiation and lithiation capacities and cycle property of Li 5 Cr 7 Ti 6 O 25 at large current densities.

Evaluation of Allogeneic Transplantation in First or Later Minimal Residual Disease-Negative Remission Following Adult-Inspired Therapy for Acute Lymphoblastic Leukemia

PubMed Central

Cassaday, Ryan D.; Alan Potts, D.; Stevenson, Philip A.; Bar, Merav; Georges, George E.; Shustov, Andrei R.; Sorror, Mohamed L.; Wood, Brent L.; Delaney, Colleen; Doney, Kristine C.; Storb, Rainer F.; Sandmaier, Brenda M.

2016-01-01

Comparisons without hematopoietic cell transplantation (HCT) to myeloablative (MAC) or reduced-intensity HCT (RIC) for adults with acute lymphoblastic leukemia (ALL) in first minimal-residual-disease negative remission (MRDNeg CR1) are limited. Further, the importance of MRDNeg following salvage therapy (MRDNeg CR2+) is unknown. We evaluated 89 patients in MRDNeg CR1 after adult-inspired treatment: 33 received MAC (12 Philadelphia chromosome [Ph]+), 17 received RIC (13 Ph+), and 39 Deferred HCT (3 Ph+). 3-year overall survival (OS) estimates for MAC, RIC, and Deferred HCT were 71%, 69%, and 68%, while 3-year event-free survival (EFS) estimates were 65%, 54%, and 28%, respectively. Further, HCT in MRDNeg CR1 performed similarly to MRDNeg CR2+: 3-year OS estimates were 70% and 69%, and 3-year EFS estimates were 62% and 62%, respectively. In conclusion, adults with ALL in MRDNeg CR1 following adult-inspired therapy had similar OS with or without HCT, and HCT in MRDNeg CR2+ can yield long-term survival. PMID:27002921

Mineralogical determination and geo-chemical modeling of chromium release from AOD slag: Distribution and leachability aspects.

PubMed

Li, Junguo; Liu, Bao; Zeng, Yanan; Wang, Ziming

2017-01-01

AOD (argon oxygen decarburization) slag, which is the by-product of the stainless steel refining process, is a recyclable slag because of its high content of calcium and silicon. The leaching toxicity cannot be ignored in the recycling process because the slag contains a certain amount of Cr. In this study, the mineral analysis, batch leaching tests and thermodynamic and kinetic modeling by PHREEQC combined with FactSage software were performed to explore the influence of the dissolution of primary minerals and the precipitation of secondary minerals on the elution of Cr from AOD slag. The results indicated that the main minerals in the original AOD slag are larnite, merwinite, pyroxene and periclase. Cr was dispersed in the mineral phases mentioned above. The simulation of Cr leaching controlled by Cr(III)-hydroxide corresponded better to the batch leaching tests, while the Cr leaching controlled by chromite or double control was underestimated. Increasing the L/S ratio enhances the pH of the leachate and restrains the elution of Cr from the AOD slag. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cr2O3-modified ZnO thick film resistors as LPG sensors.

PubMed

Patil, D R; Patil, L A

2009-02-15

Thick films of pure ZnO were obtained by screen-printing technique. Surface functionalized ZnO thick films by Cr(2)O(3) were obtained by dipping pure ZnO thick films into 0.01M aqueous solution of chromium trioxide (CrO(3)). The dipped films were fired at 500 degrees C for 30 min. Upon firing, the CrO(3) would reduce to Cr(2)O(3). Cr(2)O(3)-activated (0.47 mass%) ZnO thick films resulted in LPG sensor. Upon exposure to 100 ppm LPG, the barrier height between Cr(2)O(3) and ZnO grains decreases markedly, leading to a drastic decrease in resistance. The sensor was found to sense LPG at 350 degrees C and no cross sensitivity was observed to other hazardous, polluting and inflammable gases. The quick response ( approximately 18s) and fast recovery ( approximately 42s) are the main features of this sensor. The effects of microstructures and dopant concentrations on the gas sensing performance of the sensor were studied and discussed.

A daily herd Markov-chain model to study the reproductive and economic impact of reproductive programs combining timed artificial insemination and estrus detection.

PubMed

Giordano, J O; Kalantari, A S; Fricke, P M; Wiltbank, M C; Cabrera, V E

2012-09-01

Our objective was to compare the economic and reproductive performance of programs combining timed artificial insemination (TAI) and different levels of AI after estrus detection (ED) using a daily Markov-chain model. A dairy herd was modeled with every cow following daily probabilistic events of aging, replacement, mortality, pregnancy, pregnancy loss, and calving. The probability of pregnancy depended on the combination of probability of insemination and conception rate (CR). All nonpregnant cows had a probability of pregnancy between the end of the voluntary waiting period and days in milk cutoff for AI. After the cutoff, cows were labeled as do not breed and replaced when milk production was below a minimum milk threshold. A similar model was created to represent a replacement heifer herd to simulate and adjust the supply and demand of replacements. The net value (NV) of a program was the sum of milk income over feed cost, replacement and mortality cost, income from newborns, and reproductive costs. The model was used to compare the NV of 19 programs. One program used 100% TAI (42% CR for first TAI and 30% for second-and-later services), whereas the other programs combined TAI with ED. The proportion of cows receiving AI after ED for the combined programs ranged from 30 to 80%, with levels of CR of 25, 30, and 35%. As the proportion of cows receiving AI after ED increased, the CR of cows receiving TAI decreased. The combined programs with CR of 35% for cows receiving AI after ED had the greatest NV and reproductive performance at all levels of ED. The program using 100% TAI had greater NV and better reproductive performance than all programs with 25% CR after ED inseminations, whereas it had very similar performance to combined programs with up to 60% of cows receiving AI after ED and 30% CR. The factor with the greatest relative contribution to the differences among programs was income over feed cost, followed by replacement and reproductive costs. Adjusting the days in milk cutoff for AI to match the supply and demand of heifer replacements improved the NV of all programs except for those with 25% CR after ED, which had either no change or a decrease in NV. In summary, the economic value of reproductive management programs combining TAI and ED depended on the proportion of cows receiving AI after ED and the resulting CR. Adjusting the heifer supply and demand increased the NV of programs with heifer surplus and decreased the NV of programs with heifer deficit. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Dietary supplementation of l-arginine and chromium picolinate in sows during gestation affects the muscle fibre characteristics but not the performance of their progeny.

PubMed

Shi, Zhan; Song, Wentao; Sun, Yuecheng; Wang, Liansheng; Shi, Baoming; Shan, Anshan; Bi, Zhongpeng

2018-01-01

The present study investigated the effects of dietary supplementation of l-arginine and chromium picolinate (CrP) in sows during gestation on muscle fibre characteristics, performance and carcass characteristics of their progeny. Sixty healthy sows were randomly divided into four groups as a 2 × 2 factorial experiment design: one group received the control diet, another received the control diet + 10 g kg -1 l-arginine, the third group received the control diet + 400 ppb CrP, and the fourth group received the control diet + 10 g kg -1 l-arginine and 400 ppb CrP. The results showed that sows fed the diet supplemented with CrP produced progeny with higher muscle fibre numbers at birth, weaning and slaughter compared to sows fed the control diet. For mean fibre areas, the same result was found at weaning. For progeny of sows fed diets supplemented with l-arginine, only higher muscle fibre numbers at slaughter was observed. Almost no differences were observed regarding average daily gains, average daily feed intake, gain-to-feed ratios, carcass and meat traits. The results of the present study indicate that dietary supplementation of l-arginine and particularly CrP in sows during gestation alters muscle fibre numbers in their offspring, although not their performance or carcass characteristics. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Lack of desensitization of the cough reflex in ovalbumin-sensitized rabbits during exercise.

PubMed

Tiotiu, Angelica; Chenuel, Bruno; Foucaud, Laurent; Demoulin, Bruno; Demoulin-Alexikova, Silvia; Christov, Christo; Poussel, Mathias

2017-01-01

Cough is a major symptom of asthma frequently experienced during exercise but little is known about interactions between cough and exercise. The goal of our study was to clarify the potential modulation of the cough reflex (CR) by exercise in a spontaneously breathing anaesthetized animal model of airway eosinophilic inflammation. Ten ovalbumin (OVA) sensitized adult rabbits and 8 controls were studied. The ventilatory response to direct tracheal stimulation, performed both at rest and during exercise was determined to quantify the incidence and the sensitivity of the CR. Broncho-alveolar lavages (BAL) and cell counts were performed to assess the level of the airway inflammation following OVA-induced sensitization. Exercise was mimicked by Electrically induced hindlimb Muscular Contractions (EMC). Among 494 tracheal stimulations, 261 were performed at rest and 233 at exercise. OVA challenges in sensitized rabbits caused a significant increase in the percentage of eosinophils (p = 0.008) in BAL. EMC increased minute ventilation by 36% and 35% in OVA and control rabbits respectively, compared to rest values. The sensitivity of the CR decreased during exercise compared to baseline in control rabbits (p = 0.0313) while it remained unchanged in OVA rabbits. The desensitization of the CR during exercise in control rabbits was abolished in OVA rabbits. The precise role of airway inflammation in this lack of CR desensitization needs to be further investigated but it might contribute to the exercise-induced cough in asthmatics.

First liquid-layer implosion experiments at the NIF

NASA Astrophysics Data System (ADS)

Zylstra, Alex

2017-10-01

Replacing the standard ice layer in an ignition design with a liquid layer allows fielding the target with a higher central vapor pressure, leading to reduced implosion convergence ratio (CR). At lower CR, the implosions are expected to be more robust to instabilities and asymmetries than standard ice-layer designs, and are also unique in that the hot spot can be primarily formed from material originating in the central fuel vapor. The first liquid-layer implosions on the National Ignition Facility (NIF) have been performed by wicking the liquid fuel into a supporting foam that lines the inside surface of the capsule. A series of shots has been conducted between CR of 12 and 20 using a HDC ablator driven by a 3-shock pulse in a near-vacuum Au hohlraum. At the lowest CR the implosion performance is well predicted by 2-D radiation-hydrodynamics calculations. However, as the CR is increased the nominal simulations do not capture the experimentally observed trends. Data-based models suggest that the hot spot formation is unexpectedly suppressed at higher convergence. The data could be explained by reduced hydrodynamic coupling efficiency, or an anomalously enhanced thermal conductivity in the mixed DT/foam material. We show that the latter hypothesis can explain observed trends in several experimental metrics, including the yield, ion temperature, and burn duration. This work was performed under the auspices of the U.S. DoE by LANL under contract DE-AC52-06NA52396.

Hydrogen Induced Intergranular Cracking of Nickel-Base Alloys.

DTIC Science & Technology

1982-02-01

alloys are discussed. Experimental The steel used in the present investigation is a fully bainitic 2 1/4 Cr-lMo pressure vessel steel , ASTM A542 Class 3...Appendix A describes recent experiments performed in order to study the influence of plastic deformation on hydrogen transport in a 214 Cr-lMo steel (8...PLASTIC DEFORMATION ON HYDROGEN TRANSPORT IN 2 1/4 Cr-lMo STEEL M. Kurkela, G.S. Frankel, and R.M. Latanision Department of Materials Science and

Spontaneously hypertensive rat (SHR) as an animal model for ADHD: a short overview.

PubMed

Meneses, Alfredo; Perez-Garcia, Georgina; Ponce-Lopez, Teresa; Tellez, Ruth; Gallegos-Cari, Andrea; Castillo, Carlos

2011-01-01

Diverse studies indicate that attention-deficit hyperactivity disorder (ADHD) is associated with alterations in encoding processes, including working or short-term memory. Some ADHD dysfunctional domains are reflected in the spontaneously hypertensive rat (SHR). Because ADHD, drugs and animal models are eliciting a growing interest, hence the aim of this work is to present a brief overview with a focus on the SHR as an animal model for ADHD and memory deficits. Thus, this paper reviews the concept of SHR as a model system for ADHD, comparing SHR, Wistar-Kyoto and Sprague-Dawley rats with a focus on the hypertension level and working, short-term memory and attention in different behavioral tasks, such as open field, five choice serial reaction time, water maze, passive avoidance, and autoshaping. In addition, drug treatments (d-amphetamine and methylphenidate) are evaluated.

Effects of pressure and temperature on sintering of Cr-doped Al2O3 by pulsed electric current sintering process

NASA Astrophysics Data System (ADS)

Dang, K. Q.; Nanko, M.

2011-03-01

The aluminium oxide crystal, Al2O3, which contains a small amount of chromium, Cr, is called ruby. Pulsed electric current sintering (PECS) was applied to sinter ruby polycrystals. Cr2O3-Al2O3 powder mixture prepared by drying an aqueous slurry containing amounts of Al2O3 and Cr(NO3)3 was consolidated by PECS process. The PECS process was performed in vacuum at sintering temperature raging from 1100 to 1300°C with heating rate of 2 K/min under applied uniaxial pressure varied from 40 to 100 MPa. This study found that highly densified and transparent Cr-doped Al2O3 can be obtained by the PECS process with the high applied pressure at sintering temperature of 1200°C.

Site partitioning of Cr3+ in the trichroic alexandrite BeAl2O4:Cr3+ crystal: contribution from x-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Bordage, Amélie; Rossano, Stéphanie; Horn, Adolf Heinrich; Fuchs, Yves

2012-06-01

X-ray absorption spectroscopy measurements at the Cr K-edge of a trichroic crystal of alexandrite BeAl2O4:Cr3+ for different orientations of the crystal with respect to the polarization and direction of the x-ray incident beam have been performed. Analysis of the experimental spectra with the help of first-principles calculations of x-ray absorption spectra allowed us to estimate the proportion of chromium Cr3+ cations among the two different octahedral sites of the alexandrite structure (70% in the Cs site-30% in the Ci site). The methodology presented in this work opens up new possibilities in the field of mineralogy for the study of complex minerals containing several sites potentially occupied by several transition elements or for solid solutions.

[New perspectives in biomonitoring of metallic elements: the example of hexavalent chromium].

PubMed

Mutti, A; De Palma, G; Goldoni, M

2012-01-01

Plating industry is an important productive sector in all the national territory, because of its contribution to a high number of industrial products and crafts. In the chrome plating sector there is a specific chemical risk due to the exposure to compounds containing hexavalent Chromium [Cr(VI)]. Exhaled breath condensate (EBC) has been used to study both acute and long term exposure to Cr(VI) in chrome plating workers. Cr-EBC correlates with specific oxidative stress biomarkers. Moreover, both total Cr and its hexavalent fraction can be measured in EBC, which therefore is a promising biological fluid to assess the absorbed dose at the target organ level, the pulmonary reduction kinetics of Cr(VI) and in general its local pneumotoxic effects. EBC collection and analysis could give additional information to the traditional measures performed during biomonitoring.

Removal of Cr(VI) from Aqueous Environments Using Micelle-Clay Adsorption

PubMed Central

Qurie, Mohannad; Khamis, Mustafa; Manassra, Adnan; Ayyad, Ibrahim; Nir, Shlomo; Scrano, Laura; Bufo, Sabino A.; Karaman, Rafik

2013-01-01

Removal of Cr(VI) from aqueous solutions under different conditions was investigated using either clay (montmorillonite) or micelle-clay complex, the last obtained by adsorbing critical micelle concentration of octadecyltrimethylammonium ions onto montmorillonite. Batch experiments showed the effects of contact time, adsorbent dosage, and pH on the removal efficiency of Cr(VI) from aqueous solutions. Langmuir adsorption isotherm fitted the experimental data giving significant results. Filtration experiments using columns filled with micelle-clay complex mixed with sand were performed to assess Cr(VI) removal efficiency under continuous flow at different pH values. The micelle-clay complex used in this study was capable of removing Cr(VI) from aqueous solutions without any prior acidification of the sample. Results demonstrated that the removal effectiveness reached nearly 100% when using optimal conditions for both batch and continuous flow techniques. PMID:24222757

Indirect Effects of Elevated Body Mass Index on Memory Performance Through Altered Cerebral Metabolite Concentrations

PubMed Central

Gonzales, Mitzi M.; Takashi, Tarumi; Eagan, Danielle E.; Tanaka, Hirofumi; Vaghasia, Miral; Haley, Andreana P.

2012-01-01

Objective Elevated body mass index (BMI) at midlife is associated with increased risk of cognitive decline in later life. The goal of the current study was to assess mechanisms of early brain vulnerability by examining if higher BMI at midlife has an effect on current cognitive performance through alterations in cerebral neurochemistry. Methods Fifty-five participants, aged 40–60 years, underwent neuropsychological testing, health screen, and proton magnetic resonance spectroscopy (1H MRS) examining N-acetyl-aspartate (NAA), creatine (Cr), myo-inositol (mI), choline (Cho), and glutamate (Glu) concentrations in occipitoparietal grey matter. Concentrations of NAA, Cho, mI, and Glu were calculated as a ratio over Cr and examined in relation to BMI using multivariate regression analyses. Structural equation modeling was used to determine if BMI had an indirect effect on cognition through cerebral metabolite levels. Results Higher BMI was associated with elevations in mI/Cr (F(5,45)= 3.843, p=0.006, β=0.444, p=0.002), independent of age, sex, fasting glucose levels, and systolic blood pressure. Moreover, a chi-square difference test of the direct and indirect structural equation models revealed that BMI had an indirect effect on global cognitive performance (ΔX2(df=2) =19.939, p<0.001). Subsequent follow-up analyses revealed that this effect was specific to memory (ΔX2(df=2) = 22.027, p<0.001). Conclusions Higher BMI was associated with elevations in mI/Cr concentrations in the occipitoparietal grey matter and indirectly related to poorer memory performance through mI/Cr, potentially implicating plasma hypertonicity and neuroinflammation as mechanisms underlying obesity-related brain vulnerability. PMID:22822230

Physiological demands of running during long distance runs and triathlons.

PubMed

Hausswirth, C; Lehénaff, D

2001-01-01

The aim of this review article is to identify the main metabolic factors which have an influence on the energy cost of running (Cr) during prolonged exercise runs and triathlons. This article proposes a physiological comparison of these 2 exercises and the relationship between running economy and performance. Many terms are used as the equivalent of 'running economy' such as 'oxygen cost', 'metabolic cost', 'energy cost of running', and 'oxygen consumption'. It has been suggested that these expressions may be defined by the rate of oxygen uptake (VO2) at a steady state (i.e. between 60 to 90% of maximal VO2) at a submaximal running speed. Endurance events such as triathlon or marathon running are known to modify biological constants of athletes and should have an influence on their running efficiency. The Cr appears to contribute to the variation found in distance running performance among runners of homogeneous level. This has been shown to be important in sports performance, especially in events like long distance running. In addition, many factors are known or hypothesised to influence Cr such as environmental conditions, participant specificity, and metabolic modifications (e.g. training status, fatigue). The decrease in running economy during a triathlon and/or a marathon could be largely linked to physiological factors such as the enhancement of core temperature and a lack of fluid balance. Moreover, the increase in circulating free fatty acids and glycerol at the end of these long exercise durations bear witness to the decrease in Cr values. The combination of these factors alters the Cr during exercise and hence could modify the athlete's performance in triathlons or a prolonged run.

Structural correlates of the creatine transporter function regulation: the undiscovered country.

PubMed

Santacruz, Lucia; Jacobs, Danny O

2016-08-01

Creatine (Cr) and phosphocreatine constitute an energy shuttle that links ATP production in mitochondria to subcellular locations of ATP consumption. Cells in tissues that are reliant on this energy shuttle, such as myocytes and neurons, appear to have very limited ability to synthesize creatine. Therefore, these cells depend on Cr uptake across the cell membrane by a specialized creatine transporter (CrT solute carrier SLC6A8) in order to maintain intracellular creatine levels. Cr supplementation has been shown to have a beneficial effect in numerous in vitro and in vivo models, particularly in cases of oxidative stress, and is also widely used by athletes as a performance enhancement nutraceutical. Intracellular creatine content is maintained within narrow limits. However, the physiological and cellular mechanisms that mediate Cr transport during health and disease (such as cardiac failure) are not understood. In this narrative mini-review, we summarize the last three decades of research on CrT structure, function and regulation.

Vacuum plasma coatings for turbine blades

NASA Technical Reports Server (NTRS)

Holmes, R. R.

1985-01-01

Turbine blades, vacuum plasma spray coated with NiCrAlY, CoCrAlY or NiCrAlY/Cr2O3, were evaluated and rated superior to standard space shuttle main engine (SSME) coated blades. Ratings were based primarily on 25 thermal cycles in the MSFC Burner Rig Tester, cycling between 1700 F (gaseous H2) and -423 F (liquid H2). These tests showed no spalling on blades with improved vacuum plasma coatings, while standard blades spalled. Thermal barrier coatings of ZrO2, while superior to standard coatings, lacked the overall performance desired. Fatigue and tensile specimens, machined from MAR-M-246(Hf) test bars identical to the blades were vacuum plasma spray coated, diffusion bond treated, and tested to qualify the vacuum plasma spray process for flight hardware testing and application. While NiCrAlY/Cr2O3 offers significant improvement over standard coatings in durability and thermal protection, studies continue with an objective to develop coatings offering even greater improvements.

Elevated Temperature Corrosion Studies of AlCrN and TiAlN Coatings by PAPVD on T91 Boiler Steel

NASA Astrophysics Data System (ADS)

Goyal, Lucky; Chawla, Vikas; Hundal, Jasbir Singh

2017-11-01

The present investigation discusses the hot corrosion behavior of AlCrN and TiAlN nano-coatings on T91 boiler steel by PAPVD process subjected to molten salt of Na2SO4-60%V2O5 at 900 °C for 50 cycles. Surface and cross-sectional studies were performed by AFM, SEM/EDS and XRD techniques to understand the corrosion kinetics and mechanism. T91 bare boiler steel as well as TiAlN-coated specimen has shown higher internal oxidation as well as weight gain. The better corrosion resistance of AlCrN-coated specimen has been observed by virtue of higher availability of Cr and Al in the oxide scale as well as adherent and dense coating. The betterment of AlCrN coating can be attributed to low internal oxidation as well as movement of Cr and Al toward oxide scale to form protective corrosion barriers.

Generation of Ince-Gaussian beams in highly efficient, nanosecond Cr, Nd:YAG microchip lasers

NASA Astrophysics Data System (ADS)

Dong, J.; Ma, J.; Ren, Y. Y.; Xu, G. Z.; Kaminskii, A. A.

2013-08-01

Direct generation of higher-order Ince-Gaussian (IG) beams from laser-diode end-pumped Cr, Nd:YAG self-Q-switched microchip lasers was achieved with high efficiency and high repetition rate. An average output power of over 2 W was obtained at an absorbed pump power of 8.2 W a corresponding optical-to-optical efficiency of 25% was achieved. Various IG modes with nanosecond pulse width and peak power of over 2 kW were obtained in laser-diode pumped Cr, Nd:YAG microchip lasers under different pump power levels by applying a tilted, large area pump beam. The effect of the inversion population distribution induced by the tilted pump beam and nonlinear absorption of Cr4+-ions for different pump power levels on the oscillation of higher-order IG modes in Cr, Nd:YAG microchip lasers is addressed. The higher-order IG mode oscillation has a great influence on the laser performance of Cr, Nd:YAG microchip lasers.

Adsorption behavior comparison of trivalent and hexavalent chromium on biochar derived from municipal sludge.

PubMed

Chen, Tan; Zhou, Zeyu; Xu, Sai; Wang, Hongtao; Lu, Wenjing

2015-08-01

In this work, static equilibrium experiments were conducted to distinguish the adsorption performance between the two valence states of chromium on biochar derived from municipal sludge. The removal capacity of Cr(VI) is lower than 7mg/g at the initial chromium concentration range of 50-200mg/L, whereas that of Cr(III) higher than 20mg/g. It indicates that Cr(III) is much easier to be stabilized than Cr(VI). No significant changes in the biochar surface functional groups are observed before and after the adsorption equilibrium, demonstrating the poor contribution of organic matter in chromium adsorption. The main mechanism of heavy metal adsorption by biochar involves (1) surface precipitation through pH increase caused by biochar buffer ability, and (2) exchange between cations in solution (Cd(2+)) and in biochar matrix (e.g. Ca(2+) and Mg(2+)). The reduction of Cr(VI) to Cr(III) is necessary to improve removal efficiency of chromium. Copyright © 2015 Elsevier Ltd. All rights reserved.

Chromium in rivers impacted by tannery wastes determined by high performance liquid chromatography - inductively coupled plasma mass spectrometry

NASA Astrophysics Data System (ADS)

Pereira de Abreu, M.-H.; Vignati, D.; Dominik, J.

2003-05-01

The total chromium concentrations by ICP-MS and HPLC-ICP-MS and the redox chromium species have been determined in rivers impacted by untreated wastes from tanneries at Fès (Morocco). The results obtained by two ICP-MS analysis methods showed significantly different chromium values at m/z 53. The higher values obtained with external calibration, can be attributed to matrix effects, especially ^{37}Cl ^{16}O at m/z 53. This is confirmed on the chromatograms by the presence of a peak at 100s with the anomalous ^{52}Cr/^{53}Cr isotopic ratio. The hexavalent chromium was not detected. Two trivalent chromium monomer species, Cr(OH)(H2O)5^{2+} and Cr(H2O)6^{3+}, were present in low concentrations. We suppose that the major part of chromium occurred as Cr(III) polymeric species which were not retained on the column. These Cr(III) forms are usually complexed with Cl^- or/and SO4^{2-}, used as tanning agents.