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Sample records for accumbens shell enhances

  1. MCH and apomorphine in combination enhance action potential firing of nucleus accumbens shell neurons in vitro

    F Woodward Hopf

    2013-04-01

    Full Text Available The MCH and dopamine receptor systems have been shown to modulate a number of behaviors related to reward processing, addiction, and neuropsychiatric conditions such as schizophrenia and depression. In addition, MCH and dopamine receptors can interact in a positive manner, for example in the expression of cocaine self-administration. A recent report (Chung et al., 2011a showed that the DA1/DA2 dopamine receptor activator apomorphine suppresses pre-pulse inhibition, a preclinical model for some aspects of schizophrenia. Importantly, MCH can enhance the effects of lower doses of apomorphine, suggesting that co-modulation of dopamine and MCH receptors might alleviate some symptoms of schizophrenia with a lower dose of dopamine receptor modulator and thus fewer potential side effects. Here, we investigated whether MCH and apomorphine could enhance action potential firing in vitro in the nucleus accumbens shell (NAshell, a region which has previously been shown to mediate some behavioral effects of MCH. Using whole-cell patch-clamp electrophysiology, we found that MCH, which has no effect on firing on its own, was able to increase NAshell firing when combined with a subthreshold dose of apomorphine. Further, this MCH/apomorphine increase in firing was prevented by an antagonist of either a DA1 or a DA2 receptor, suggesting that apomorphine acts through both receptor types to enhance NAshell firing. The MCH/apomorphine-mediated firing increase was also prevented by an MCH receptor antagonist or a PKA inhibitor. Taken together, our results suggest that MCH can interact with lower doses of apomorphine to enhance NAshell firing, and thus that MCH and apomorphine might interact in vivo within the NAshell to suppress pre-pulse inhibition.

  2. Preferential enhancement of dopamine transmission within the nucleus accumbens shell by cocaine is due to a direct increase in phasic dopamine release events

    Aragona, Brandon J.; Cleaveland, Nathan A.; Stuber, Garret D.; Day, Jeremy J.; Carelli, Regina M.; Wightman, R. Mark

    2008-01-01

    Preferential enhancement of dopamine transmission within the nucleus accumbens (NAc) shell is a fundamental aspect of the neural regulation of cocaine reward. Despite its importance, the nature of this effect is poorly understood. Here, we used fast-scan cyclic voltammetry to examine specific transmission processes underlying cocaine-evoked increases in dopamine transmission within the NAc core and shell. Initially, we examined altered terminal dopamine concentrations following global autorec...

  3. Methamphetamine-induced enhancement of hippocampal long-term potentiation is modulated by NMDA and GABA receptors in the shell-accumbens.

    Heysieattalab, Soomaayeh; Naghdi, Nasser; Hosseinmardi, Narges; Zarrindast, Mohammad-Reza; Haghparast, Abbas; Khoshbouei, Habibeh

    2016-08-01

    Addictive drugs modulate synaptic transmission in the meso-corticolimbic system by hijacking normal adaptive forms of experience-dependent synaptic plasticity. Psychostimulants such as METH have been shown to affect hippocampal synaptic plasticity, albeit with a less understood synaptic mechanism. METH is one of the most addictive drugs that elicit long-term alterations in the synaptic plasticity in brain areas involved in reinforcement learning and reward processing. Dopamine transporter (DAT) is one of the main targets of METH. As a substrate for DAT, METH decreases dopamine uptake and increases dopamine efflux via the transporter in the target brain regions such as nucleus accumbens (NAc) and hippocampus. Due to cross talk between NAc and hippocampus, stimulation of NAc has been shown to alter hippocampal plasticity. In this study, we tested the hypothesis that manipulation of glutamatergic and GABA-ergic systems in the shell-NAc modulates METH-induced enhancement of long term potentiation (LTP) in the hippocampus. Rats treated with METH (four injections of 5 mg/kg) exhibited enhanced LTP as compared to saline-treated animals. Intra-NAc infusion of muscimol (GABA receptor agonist) decreased METH-induced enhancement of dentate gyrus (DG)-LTP, while infusion of AP5 (NMDA receptor antagonist) prevented METH-induced enhancement of LTP. These data support the interpretation that reducing NAc activity can ameliorate METH-induced hippocampal LTP through a hippocampus-NAc-VTA circuit loop. Synapse 70:325-335, 2016. © 2016 Wiley Periodicals, Inc. PMID:27029021

  4. A relationship between reduced nucleus accumbens shell and enhanced lateral hypothalamic orexin neuronal activation in long-term fructose bingeing behavior.

    Jacki M Rorabaugh

    Full Text Available Fructose accounts for 10% of daily calories in the American diet. Fructose, but not glucose, given intracerebroventricularly stimulates homeostatic feeding mechanisms within the hypothalamus; however, little is known about how fructose affects hedonic feeding centers. Repeated ingestion of sucrose, a disaccharide of fructose and glucose, increases neuronal activity in hedonic centers, the nucleus accumbens (NAc shell and core, but not the hypothalamus. Rats given glucose in the intermittent access model (IAM display signatures of hedonic feeding including bingeing and altered DA receptor (R numbers within the NAc. Here we examined whether substituting fructose for glucose in this IAM produces bingeing behavior, alters DA Rs and activates hedonic and homeostatic feeding centers. Following long-term (21-day exposure to the IAM, rats given 8-12% fructose solutions displayed fructose bingeing but unaltered DA D1R or D2R number. Fructose bingeing rats, as compared to chow bingeing controls, exhibited reduced NAc shell neuron activation, as determined by c-Fos-immunoreactivity (Fos-IR. This activation was negatively correlated with orexin (Orx neuron activation in the lateral hypothalamus/perifornical area (LH/PeF, a brain region linking homeostatic to hedonic feeding centers. Following short-term (2-day access to the IAM, rats exhibited bingeing but unchanged Fos-IR, suggesting only long-term fructose bingeing increases Orx release. In long-term fructose bingeing rats, pretreatment with the Ox1R antagonist SB-334867 (30 mg/kg; i.p. equally reduced fructose bingeing and chow intake, resulting in a 50% reduction in calories. Similarly, in control rats, SB-334867 reduced chow/caloric intake by 60%. Thus, in the IAM, Ox1Rs appear to regulate feeding based on caloric content rather than palatability. Overall, our results, in combination with the literature, suggest individual monosaccharides activate distinct neuronal circuits to promote feeding behavior

  5. Interactions between Brainstem Noradrenergic Neurons and the Nucleus Accumbens Shell in Modulating Memory for Emotionally Arousing Events

    Kerfoot, Erin C.; Williams, Cedric L.

    2011-01-01

    The nucleus accumbens shell (NAC) receives axons containing dopamine-[beta]-hydroxylase that originate from brainstem neurons in the nucleus of the solitary tract (NTS). Recent findings show that memory enhancement produced by stimulating NTS neurons after learning may involve interactions with the NAC. However, it is unclear whether these…

  6. Accumbens Shell AMPA Receptors Mediate Expression of Extinguished Reward Seeking through Interactions with Basolateral Amygdala

    Millan, E. Zayra; McNally, Gavan P.

    2011-01-01

    Extinction is the reduction in drug seeking when the contingency between drug seeking behavior and the delivery of drug reward is broken. Here, we investigated a role for the nucleus accumbens shell (AcbSh). Rats were trained to respond for 4% (v/v) alcoholic beer in one context (Context A) followed by extinction in a second context (Context B).…

  7. Neuropeptide Y infusion into the shell region of the rat nucleus accumbens increases extracellular levels of dopamine

    Sørensen, Gunnar; Wegener, Gregers; Hasselstrøm, Jørgen;

    2009-01-01

    Increases in extracellular dopamine in the shell region of the nucleus accumbens are centrally involved in mediating reinforcement of addictive drugs. Neuropeptide Y (NPY) and its receptors are present in the nucleus accumbens and have been implicated in addiction mechanisms. This study further e...

  8. The nucleus accumbens shell and the dorsolateral striatum mediate the reinforcing effects of cocaine through a serial connection

    Veeneman, Maartje M J; Damsteegt, Ruth; Vanderschuren, Louk J M J

    2015-01-01

    The reinforcing and addictive properties of cocaine are thought to rely on the dopaminergic innervation of the striatum. The ventromedial [i.e. nucleus accumbens shell (NAcc) shell] and dorsolateral [dorsolateral striatum (DLS)] regions of the striatum are serially connected, and it is thought that

  9. TRH injected into the nucleus accumbens shell releases dopamine and reduces feeding motivation in rats.

    Puga, L; Alcántara-Alonso, V; Coffeen, U; Jaimes, O; de Gortari, P

    2016-06-01

    The thyrotropin-releasing hormone (TRH), an anorexigenic factor that reduces food intake in food-restricted animals, may be involved in motivation for food. Injected centrally, TRH impairs acquisition of food-rewarded behavior. Through the TRH-R1 receptors, TRH injected in the nucleus accumbens increases dopamine content-perhaps the mechanism by which the peptide modulates food motivation. This, however, is still to be demonstrated. We sought to evaluate dopamine release by microdialysis after a TRH injection into the nucleus accumbens shell in free-moving fasted rats. In addition, we assessed dopamine content and turnover by HPLC and the relationship with the motivation for food by analyzing the performance of rats during a progressive-ratio (PR) operant-conditioning test. Finally, we determined serum leptin and triiodothyronine (T3) levels in order to evaluate the animals' metabolic response to food restriction and the impact of intra-accumbal TRH administration on circulating hormones. Intra-accumbal injections of TRH reduced food intake in food-restricted rats-compared to counterparts treated with saline-, without further decreasing T3 or leptin levels, which dropped due to their dietary regime. TRH-injected rats had lower breaking points on the PR schedule, which indicated lower motivation to eat. Accordingly, compared to saline-treated animals, dopamine release and turnover increased in the nucleus accumbens of TRH-injected rats, a finding that suggests a relationship between motivation for food and TRH-induced release of dopamine. PMID:27006143

  10. The Role of Nucleus Accumbens Shell in Learning about Neutral versus Excitatory Stimuli during Pavlovian Fear Conditioning

    Bradfield, Laura A.; McNally, Gavan P.

    2010-01-01

    We studied the role of nucleus accumbens shell (AcbSh) in Pavlovian fear conditioning. Rats were trained to fear conditioned stimulus A (CSA) in Stage I, which was then presented in compound with a neutral stimulus and paired with shock in Stage II. AcbSh lesions had no effect on fear-learning to CSA in Stage I, but selectively prevented learning…

  11. No Evidence for Sex Differences in the Electrophysiological Properties and Excitatory Synaptic Input onto Nucleus Accumbens Shell Medium Spiny Neurons.

    Willett, Jaime A; Will, Tyler; Hauser, Caitlin A; Dorris, David M; Cao, Jinyan; Meitzen, John

    2016-01-01

    Sex differences exist in how the brain regulates motivated behavior and reward, both in normal and pathological contexts. Investigations into the underlying neural mechanisms have targeted the striatal brain regions, including the dorsal striatum and nucleus accumbens core and shell. These investigations yield accumulating evidence of sexually different electrophysiological properties, excitatory synaptic input, and sensitivity to neuromodulator/hormone action in select striatal regions both before and after puberty. It is unknown whether the electrical properties of neurons in the nucleus accumbens shell differ by sex, and whether sex differences in excitatory synaptic input are present before puberty. To test the hypothesis that these properties differ by sex, we performed whole-cell patch-clamp recordings on male and female medium spiny neurons (MSNs) in acute brain slices obtained from prepubertal rat nucleus accumbens shell. We analyzed passive and active electrophysiological properties, and miniature EPSCs (mEPSCs). No sex differences were detected; this includes those properties, such as intrinsic excitability, action potential afterhyperpolarization, threshold, and mEPSC frequency, that have been found to differ by sex in other striatal regions and/or developmental periods. These findings indicate that, unlike other striatal brain regions, the electrophysiological properties of nucleus accumbens shell MSNs do not differ by sex. Overall, it appears that sex differences in striatal function, including motivated behavior and reward, are likely mediated by other factors and striatal regions. PMID:27022621

  12. Neural Encoding of Cocaine Seeking Behavior is Coincident with Phasic Dopamine Release in the Accumbens Core and Shell

    Owesson-White, Catarina A.; Ariansen, Jennifer; Stuber, Garret D.; Cleaveland, Nathan A.; Cheer, Joseph F.; Wightman, R. Mark; Carelli, Regina M.

    2009-01-01

    Mesolimbic dopamine neurons projecting from the ventral tegmental area (VTA) to the nucleus accumbens (NAc) are part of a complex circuit mediating cocaine-directed behaviors. However, the precise role of rapid (subsecond) dopamine release within the primary sub-regions of the NAc, the core and shell, and its relationship to NAc cell firing during this behavior remain unknown. Here, using fast-scan cyclic voltammetry (FSCV) we report rapid dopamine signaling in both the core and shell, howeve...

  13. Nucleus accumbens shell, but not core, tracks motivational value of salt.

    Loriaux, Amy L; Roitman, Jamie D; Roitman, Mitchell F

    2011-09-01

    To appropriately respond to an affective stimulus, we must be able to track its value across changes in both the external and internal environment. The nucleus accumbens (NAc) is a critical component of reward circuitry, but recent work suggests that the NAc encodes aversion as well as reward. It remains unknown whether differential NAc activity reflects flexible changes in stimulus value when it is altered due to a change in physiological state. We measured the activity of individual NAc neurons when rats were given intraoral infusions of a hypertonic salt solution (0.45 M NaCl) across multiple sessions in which motivational state was manipulated. This normally nonpreferred taste was made rewarding via sodium depletion, which resulted in a strong motivation to seek out and consume salt. Recordings were made in three conditions: while sodium replete (REP), during acute sodium depletion (DEP), and following replenishment of salt to normal sodium balance (POST). We found that NAc neurons in the shell and core subregions responded differently across the three conditions. In the shell, we observed overall increases in NAc activity when the salt solution was nonpreferred (REP) but decreases when the salt solution was preferred (DEP). In the core, overall activity was significantly altered only after sodium balance was restored (POST). The results lend further support to the selective encoding of affective stimuli by the NAc and suggest that NAc shell is particularly involved in flexibly encoding stimulus value based on motivational state. PMID:21697439

  14. Nucleus accumbens core and shell are necessary for reinforcer devaluation effects on Pavlovian conditioned responding

    Geoffrey Schoenbaum

    2010-10-01

    Full Text Available The nucleus accumbens (NA has been hypothesized to be part of a circuit in which cue-evoked information about expected outcomes is mobilized to guide behavior. Here we tested this hypothesis using a Pavlovian reinforcer devaluation task, previously applied to assess outcome-guided behavior after damage to regions such as the orbitofrontal cortex and amygdala that send projections to NA. Rats with sham lesions or neurotoxic lesions of either the core or shell subdivision of NA were trained to associate a 10 sec CS+ with delivery of three food pellets. After training, half of the rats in each lesion group received food paired with illness induced by LiCl injections; the remaining rats received food and illness unpaired. Subsequently, responding to the CS+ was assessed in an extinction probe test. Both sham and lesioned rats conditioned to the CS+ and formed a conditioned taste aversion. However only sham rats reduced their conditioned responding as a result of reinforcer devaluation; devalued rats with lesions of either core or shell showed levels of responding that were similar to lesioned, non-devalued rats. This impairment was not due to the loss of motivational salience conferred to the CS+ in lesioned rats as both groups responded similarly for the cue in conditioned reinforcement testing. These data suggest that NA core and shell are part of a circuit necessary for the use of cue-evoked information about expected outcomes to guide behavior.

  15. The dorsomedial shell of the nucleus accumbens facilitates cocaine-induced locomotor activity during the induction of behavioral sensitization.

    Todtenkopf, M S; Carreiras, T; Melloni, R H; Stellar, J R

    2002-04-01

    The mesolimbic dopamine system has been intensely studied as the neural circuit mediating the locomotor response to psychostimulants and behavioral sensitization. In particular, the dopaminergic innervation of the nucleus accumbens has been implicated as a site responsible for the manifestations of behavioral sensitization. Previous studies have demonstrated an augmented release of dopamine in the nucleus accumbens upon a systemic injection of a psychostimulant. In addition, alterations in the dopaminergic innervation patterns in this brain region have been demonstrated in animals that received repeated injections of cocaine. Furthermore, lesions of projection sites that have terminations in the nucleus accumbens have demonstrated alterations in psychostimulant induced locomotion, both acutely, as well as in sensitization paradigms. Since dopamine in the nucleus accumbens is believed to regulate several excitatory amino acid inputs, the present study examined the effects of a localized electrolytic lesion in the dorsomedial shell of the nucleus accumbens in order to better understand the functional role this brain region has in behavioral sensitization. All animals received bi-daily injections of 15 mg/kg i.p. cocaine. Only those demonstrating behavioral sensitization after a subsequent challenge dose were included in the analysis. Following acute exposure to cocaine, lesioned animals did not show any difference in their locomotor response when compared with sham controls. However, after repeated exposure to cocaine, sensitized animals demonstrated a significant attenuation in locomotor behavior when compared with sensitized sham controls. This decrease in horizontal locomotion persisted 2 days into withdrawal, yet dissipated in the sensitized animals that were challenged 2 weeks following their last injection. The data presented here demonstrate that the dorsomedial shell of the nucleus accumbens plays an important role in the initial stages of behavioral

  16. Cue-evoked dopamine release in the nucleus accumbens shell tracks reinforcer magnitude during intracranial self-stimulation

    Beyene, Manna; Carelli, Regina M.; Wightman, R. Mark

    2010-01-01

    The mesolimbic dopamine system is critically involved in modulating reward-seeking behavior and is transiently activated upon presentation of reward-predictive cues. It has previously been shown, using fast-scan cyclic voltammetry in behaving rats, that cues predicting a variety of reinforcers including food/water, cocaine or intracranial self-stimulation (ICSS) elicit time-locked transient fluctuations in dopamine concentration in the nucleus accumbens (NAc) shell. These dopamine transients ...

  17. Activation of CREB in the nucleus accumbens shell produces anhedonia and resistance to extinction of fear in rats

    Muschamp, John W.; Van’t Veer, Ashlee; Parsegian, Aram; Gallo, Miranda S.; Chen, Melissa; Neve, Rachael L; Meloni, Edward G.; Carlezon, William A.

    2011-01-01

    Stress triggers psychiatric conditions including depressive and anxiety disorders. The mechanisms by which stress produces persistent changes in behavior are not fully understood. Here we show in rats that stress (footshock) activates the transcription factor CREB (cAMP response element binding protein) within the nucleus accumbens shell (NAS), a brain area involved in encoding reward and aversion. To examine the behavioral significance of altered CREB function in the NAS, we used viral vecto...

  18. Nucleus accumbens core lesions enhance two-way active avoidance

    Lichtenberg, Nina T.; Kashtelyan, Vadim; Burton, Amanda C.; Bissonette, Gregory B.; Roesch, Matthew R.

    2013-01-01

    The majority of work examining nucleus accumbens core (NAc) has focused on functions pertaining to behaviors guided by appetitive outcomes. These studies have pointed to NAc as being critical for motivating behavior toward desirable outcomes. For example, we have recently shown that lesions of NAc impaired performance on a reward-guided decision-making task that required rats to choose between differently valued rewards. Unfortunately, much less is known about the role that NAc plays in motiv...

  19. In Vivo Chronic Intermittent Ethanol Exposure Reverses the Polarity of Synaptic Plasticity in the Nucleus Accumbens Shell

    Jeanes, Zachary M.; Buske, Tavanna R.; Morrisett, Richard A.

    2011-01-01

    Glutamatergic synaptic plasticity in the nucleus accumbens (NAc) is implicated in response to sensitization to psychomotor-stimulating agents, yet ethanol effects here are undefined. We studied the acute in vitro and in vivo effects of ethanol in medium spiny neurons from the shell NAc subregion of slices of C57BL/6 mice by using whole-cell voltage-clamp recordings of α-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) excitatory postsynaptic current (EPSCs). Synaptic conditioning (l...

  20. Reversal of morphine-induced cell-type-specific synaptic plasticity in the nucleus accumbens shell blocks reinstatement.

    Hearing, Matthew C; Jedynak, Jakub; Ebner, Stephanie R; Ingebretson, Anna; Asp, Anders J; Fischer, Rachel A; Schmidt, Clare; Larson, Erin B; Thomas, Mark John

    2016-01-19

    Drug-evoked plasticity at excitatory synapses on medium spiny neurons (MSNs) of the nucleus accumbens (NAc) drives behavioral adaptations in addiction. MSNs expressing dopamine D1 (D1R-MSN) vs. D2 receptors (D2R-MSN) can exert antagonistic effects in drug-related behaviors, and display distinct alterations in glutamate signaling following repeated exposure to psychostimulants; however, little is known of cell-type-specific plasticity induced by opiates. Here, we find that repeated morphine potentiates excitatory transmission and increases GluA2-lacking AMPA receptor expression in D1R-MSNs, while reducing signaling in D2-MSNs following 10-14 d of forced abstinence. In vivo reversal of this pathophysiology with optogenetic stimulation of infralimbic cortex-accumbens shell (ILC-NAc shell) inputs or treatment with the antibiotic, ceftriaxone, blocked reinstatement of morphine-evoked conditioned place preference. These findings confirm the presence of overlapping and distinct plasticity produced by classes of abused drugs within subpopulations of MSNs that may provide targetable molecular mechanisms for future pharmacotherapies. PMID:26739562

  1. Nucleus accumbens shell, but not core, tracks motivational value of salt

    Loriaux, Amy L.; Roitman, Jamie D.; Roitman, Mitchell F.

    2011-01-01

    To appropriately respond to an affective stimulus, we must be able to track its value across changes in both the external and internal environment. The nucleus accumbens (NAc) is a critical component of reward circuitry, but recent work suggests that the NAc encodes aversion as well as reward. It remains unknown whether differential NAc activity reflects flexible changes in stimulus value when it is altered due to a change in physiological state. We measured the activity of individual NAc neu...

  2. Role of Dopamine Receptors Subtypes, D1-Like and D2-Like, within the Nucleus Accumbens Subregions, Core and Shell, on Memory Consolidation in the One-Trial Inhibitory Avoidance Task

    Manago, Francesca; Castellano, Claudio; Oliverio, Alberto; Mele, Andrea; De Leonibus, Elvira

    2009-01-01

    Recent evidence demonstrated that dopamine within the nucleus accumbens mediates consolidation of both associative and nonassociative memories. However, the specific contribution of the nucleus accumbens subregions, core and shell, and of D1 and D2 receptors subtypes has not been yet clarified. The aim of this study was, therefore, to directly…

  3. Differential Effects of Blockade of Dopamine D1-Family Receptors in Nucleus Accumbens Core or Shell on Reinstatement of Heroin Seeking Induced by Contextual and Discrete Cues

    Bossert, Jennifer M.; Poles, Gabriela C.; Wihbey, Kristina A.; Koya, Eisuke; Shaham, Yavin

    2007-01-01

    In humans, exposure to environmental contexts previously associated with heroin intake can provoke drug relapse, but the neuronal mechanisms mediating this relapse are unknown. Using a drug relapse model, we found previously that reexposing rats to heroin-associated contexts, after extinction of drug-reinforced responding in different contexts, reinstates heroin seeking. This effect is attenuated by inhibition of glutamate transmission in the ventral tegmental area and medial accumbens shell,...

  4. Alterations in blood glucose and plasma glucagon concentrations during deep brain stimulation in the shell region of the nucleus accumbens in rats

    SusanneEla Fleur; Geoffreyvan der Plasse; MatthijsFeenstra; AndriesKalsbeek

    2013-01-01

    Deep brain stimulation (DBS) of the nucleus accumbens (NAc) is an effective therapy for obsessive compulsive disorder (OCD) and is currently under investigation as a treatment for eating disorders. DBS of this area is associated with altered food intake and pharmacological treatment of OCD is associated with the risk of developing type 2 diabetes. Therefore we examined if DBS of the NAc-shell (sNAc) influences glucose metabolism. Male Wistar rats were subjected to DBS, or sham stimulation...

  5. Modulation of memory consolidation by the basolateral amygdala or nucleus accumbens shell requires concurrent dopamine receptor activation in both brain regions

    LaLumiere, Ryan T; Nawar, Erene M.; McGaugh, James L.

    2005-01-01

    Previous findings indicate that the basolateral amygdala (BLA) and the nucleus accumbens (NAc) interact in influencing memory consolidation. The current study investigated whether this interaction requires concurrent dopamine (DA) receptor activation in both brain regions. Unilateral, right-side cannulae were implanted into the BLA and the ipsilateral NAc shell or core in male Sprague-Dawley rats (∼300 g). One week later, the rats were trained on an inhibitory avoidance (IA) task and, 48 h la...

  6. Behavioral Flexibility Is Increased by Optogenetic Inhibition of Neurons in the Nucleus Accumbens Shell during Specific Time Segments

    Aquili, Luca; Liu, Andrew W.; Shindou, Mayumi; Shindou, Tomomi; Wickens, Jeffery R.

    2014-01-01

    Behavioral flexibility is vital for survival in an environment of changing contingencies. The nucleus accumbens may play an important role in behavioral flexibility, representing learned stimulus-reward associations in neural activity during response selection and learning from results. To investigate the role of nucleus accumbens neural activity…

  7. Nucleus accumbens shell excitability is decreased by methamphetamine self-administration and increased by 5-HT2C receptor inverse agonism and agonism

    Graves, Steven M.; Clark, Mary J.; Traynor, John R.; Hu, Xiu-Ti; Napier, T. Celeste

    2014-01-01

    Methamphetamine profoundly increases brain monoamines and is a widely abused psychostimulant. The effects of methamphetamine self-administration on neuron function are not known for the nucleus accumbens, a brain region involved in addictive behaviors, including drug-seeking. One therapeutic target showing preclinical promise at attenuating psychostimulant-seeking is 5-HT2C receptors; however, the effects of 5-HT2C receptor ligands on neuronal physiology are unclear. 5-HT2C receptor agonism decreases psychostimulant-mediated behaviors, and the putative 5-HT2C receptor inverse agonist, SB 206553, attenuates methamphetamine-seeking in rats. To ascertain the effects of methamphetamine, and 5-HT2C receptor inverse agonism and agonism, on neuronal function in the nucleus accumbens, we evaluated methamphetamine, SB 206553, and the 5-HT2C receptor agonist and Ro 60-0175, on neuronal excitability within the accumbens shell subregion using whole-cell current-clamp recordings in forebrain slices ex vivo. We reveal that methamphetamine self-administration decreased generation of evoked action potentials. In contrast, SB 206553 and Ro 60-0175 increased evoked spiking, effects that were prevented by the 5-HT2C receptor antagonist, SB 242084. We also assessed signaling mechanisms engaged by 5-HT2C receptors, and determined that accumbal 5-HT2C receptors stimulated Gq, but not Gi/o. These findings demonstrate that methamphetamine-induced decreases in excitability of neurons within the nucleus accumbens shell were abrogated by both 5-HT2C inverse agonism and agonism, and this effect likely involved activation of Gq–mediated signaling pathways. PMID:25229719

  8. In vivo chronic intermittent ethanol exposure reverses the polarity of synaptic plasticity in the nucleus accumbens shell.

    Jeanes, Zachary M; Buske, Tavanna R; Morrisett, Richard A

    2011-01-01

    Glutamatergic synaptic plasticity in the nucleus accumbens (NAc) is implicated in response to sensitization to psychomotor-stimulating agents, yet ethanol effects here are undefined. We studied the acute in vitro and in vivo effects of ethanol in medium spiny neurons from the shell NAc subregion of slices of C57BL/6 mice by using whole-cell voltage-clamp recordings of α-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) excitatory postsynaptic current (EPSCs). Synaptic conditioning (low-frequency stimulation with concurrent postsynaptic depolarization) reliably depressed AMPA EPSCs by nearly 30%; this accumbal long-term depression (LTD) was blocked by a nonselective N-methyl-D-aspartate (NMDA) receptor antagonist (DL-2-amino-5-phosphonovaleric acid) and a selective NMDA receptor 2B antagonist [R-(R*,S*)-α-(4-hydroxyphenyl)-β-methyl-4-(phenylmethyl)-1-piperidine propanol]. Acute ethanol exposure inhibited the depression of AMPA EPSCs differentially with increasing concentrations, but this inhibitory action of ethanol was occluded by a D1-selective dopamine receptor agonist. Ethanol dependence was elicited in C57BL/6 mice by two separate 4-day bouts of chronic intermittent ethanol (CIE) vapor exposure. When assessed 24 h after a single bout of in vivo CIE vapor exposure, NAc LTD was absent, and instead NMDA receptor-dependent synaptic potentiation [long-term potentiation (LTP)] was reliably observed. It is noteworthy that both LTP and LTD were completely absent after an extended withdrawal (72 h) after a single 3-day CIE vapor bout. These observations demonstrate that 1) accumbal synaptic depression is mediated by NR2B receptors, 2) accumbal synaptic depression is highly sensitive to both acute and chronic ethanol exposure, and 3) alterations in this synaptic process may constitute a neural adaptation that contributes to the induction and/or expression of ethanol dependence. PMID:20947635

  9. Deep brain stimulation reveals a dissociation of consummatory and motivated behaviour in the medial and lateral nucleus accumbens shell of the rat.

    van der Plasse, Geoffrey; Schrama, Regina; van Seters, Sebastiaan P; Vanderschuren, Louk J M J; Westenberg, Herman G M

    2012-01-01

    Following the successful application of deep brain stimulation (DBS) in the treatment of Parkinson's disease and promising results in clinical trials for obsessive compulsive disorder and major depression, DBS is currently being tested in small patient-populations with eating disorders and addiction. However, in spite of its potential use in a broad spectrum of disorders, the mechanisms of action of DBS remain largely unclear and optimal neural targets for stimulation in several disorders have yet to be established. Thus, there is a great need to examine site-specific effects of DBS on a behavioural level and to understand how DBS may modulate pathological behaviour. In view of the possible application of DBS in the treatment of disorders characterized by impaired processing of reward and motivation, like addiction and eating disorders, we examined the effect of DBS of the nucleus accumbens (NAcc) on food-directed behavior. Rats were implanted with bilateral stimulation electrodes in one of three anatomically and functionally distinct sub-areas of the NAcc: the core, lateral shell (lShell) and medial shell (mShell). Subsequently, we studied the effects of DBS on food consumption, and the motivational and appetitive properties of food. The data revealed a functional dissociation between the lShell and mShell. DBS of the lShell reduced motivation to respond for sucrose under a progressive ratio schedule of reinforcement, mShell DBS, however, profoundly and selectively increased the intake of chow. DBS of the NAcc core did not alter any form of food-directed behavior studied. DBS of neither structure affected sucrose preference. These data indicate that the intake of chow and the motivation to work for palatable food can independently be modulated by DBS of subregions of the NAcc shell. As such, these findings provide important leads for the possible future application of DBS as a treatment for eating disorders such as anorexia nervosa. PMID:22428054

  10. Deep brain stimulation reveals a dissociation of consummatory and motivated behaviour in the medial and lateral nucleus accumbens shell of the rat.

    Geoffrey van der Plasse

    Full Text Available Following the successful application of deep brain stimulation (DBS in the treatment of Parkinson's disease and promising results in clinical trials for obsessive compulsive disorder and major depression, DBS is currently being tested in small patient-populations with eating disorders and addiction. However, in spite of its potential use in a broad spectrum of disorders, the mechanisms of action of DBS remain largely unclear and optimal neural targets for stimulation in several disorders have yet to be established. Thus, there is a great need to examine site-specific effects of DBS on a behavioural level and to understand how DBS may modulate pathological behaviour. In view of the possible application of DBS in the treatment of disorders characterized by impaired processing of reward and motivation, like addiction and eating disorders, we examined the effect of DBS of the nucleus accumbens (NAcc on food-directed behavior. Rats were implanted with bilateral stimulation electrodes in one of three anatomically and functionally distinct sub-areas of the NAcc: the core, lateral shell (lShell and medial shell (mShell. Subsequently, we studied the effects of DBS on food consumption, and the motivational and appetitive properties of food. The data revealed a functional dissociation between the lShell and mShell. DBS of the lShell reduced motivation to respond for sucrose under a progressive ratio schedule of reinforcement, mShell DBS, however, profoundly and selectively increased the intake of chow. DBS of the NAcc core did not alter any form of food-directed behavior studied. DBS of neither structure affected sucrose preference. These data indicate that the intake of chow and the motivation to work for palatable food can independently be modulated by DBS of subregions of the NAcc shell. As such, these findings provide important leads for the possible future application of DBS as a treatment for eating disorders such as anorexia nervosa.

  11. Prolonged Consumption of Sucrose in a Binge-Like Manner, Alters the Morphology of Medium Spiny Neurons in the Nucleus Accumbens Shell.

    Paul M Klenowski

    2016-03-01

    Full Text Available The modern diet has become highly sweetened, resulting in unprecedented levels of sugar consumption, particularly among adolescents. While chronic long-term sugar intake is known to contribute to the development of metabolic disorders including obesity and type II diabetes, little is known regarding the direct consequences of long-term, binge-like sugar consumption on the brain. Because sugar can cause the release of dopamine in the nucleus accumbens (NAc similarly to drugs of abuse, we investigated changes in the morphology of neurons in this brain region following short- (4 weeks and long-term (12 weeks binge-like sucrose consumption using an intermittent two-bottle choice paradigm. We used Golgi-Cox staining to impregnate medium spiny neurons (MSNs from the NAc core and shell of short- and long-term sucrose consuming rats and compared these to age matched water controls. We show that prolonged binge-like sucrose consumption significantly decreased the total dendritic length of NAc shell MSNs compared to age-matched control rats. We also found that the restructuring of these neurons resulted primarily from reduced distal dendritic complexity. Conversely, we observed increased spine densities at the distal branch orders of NAc shell MSNs from long-term sucrose consuming rats. Combined, these results highlight the neuronal effects of prolonged binge-like intake of sucrose on NAc shell MSN morphology.

  12. The role of nucleus accumbens core/shell in sleep-wake regulation and their involvement in modafinil-induced arousal.

    Mei-Hong Qiu

    Full Text Available BACKGROUND: We have previously shown that modafinil promotes wakefulness via dopamine receptor D(1 and D(2 receptors; however, the locus where dopamine acts has not been identified. We proposed that the nucleus accumbens (NAc that receives the ventral tegmental area dopamine inputs play an important role not only in reward and addiction but also in sleep-wake cycle and in mediating modafinil-induced arousal. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we further explored the role of NAc in sleep-wake cycle and sleep homeostasis by ablating the NAc core and shell, respectively, and examined arousal response following modafinil administration. We found that discrete NAc core and shell lesions produced 26.5% and 17.4% increase in total wakefulness per day, respectively, with sleep fragmentation and a reduced sleep rebound after a 6-hr sleep deprivation compared to control. Finally, NAc core but not shell lesions eliminated arousal effects of modafinil. CONCLUSIONS/SIGNIFICANCE: These results indicate that the NAc regulates sleep-wake behavior and mediates arousal effects of the midbrain dopamine system and stimulant modafinil.

  13. Alcohol-preferring (P) rats are more sensitive than Wistar rats to the reinforcing effects of cocaine self-administered directly into the nucleus accumbens shell.

    Katner, Simon N; Oster, Scott M; Ding, Zheng-Ming; Deehan, Gerald A; Toalston, Jamie E; Hauser, Sheketha R; McBride, William J; Rodd, Zachary A

    2011-10-01

    Wistar rats will self-administer cocaine directly into the nucleus accumbens shell (AcbSh), but not into the nucleus accumbens core. In human and animal literature, there is a genetic association between alcoholism and cocaine dependency. The current experiment examined whether selective breeding for high alcohol preference is also associated with greater sensitivity of the AcbSh to the reinforcing properties of cocaine. P and Wistar rats were given cocaine (0, 100, 200, 400, or 800 pmol/100 nl) to self-infuse into the AcbSh. Rats were given cocaine for the first 4 sessions (acquisition), artificial CSF for sessions 5 and 6 (extinction), and cocaine again in session 7 (reinstatement). During acquisition, P rats self-infused 200-800 pmol cocaine (59 infusions/session), whereas Wistar rats only reliably self-infused 800 pmol cocaine (38 infusions/session). Furthermore, P rats received a greater number of cocaine infusions in the 200, 400 and 800 pmol cocaine groups compared to respective Wistar groups during acquisition. Both P and Wistar rats reduced responding on the active lever when aCSF was substituted for cocaine, and reinstated responding in session 7 when cocaine was restored. However, P rats had significantly greater infusions during session 7 compared to session 4 at all concentrations of cocaine tested, whereas Wistar rats only displayed greater infusions during session 7 compared to session 4 at the 400 and 800 pmol cocaine concentrations. The present results suggest that, compared to Wistar rats, the AcbSh of P rats was more sensitive to the reinforcing effects of cocaine. The reinstatement data suggest that the AcbSh of P rats may have become sensitized to the reinforcing effects of cocaine. Overall, the findings from this study support a genetic association between high alcohol preference and greater sensitivity to the reinforcing effects of cocaine. PMID:21723879

  14. Maternal deprivation enhances behavioral vulnerability to stress associated with miR-504 expression in nucleus accumbens of rats.

    Yi Zhang

    Full Text Available OBJECTIVE: In this study, the effect of maternal deprivation (MD and chronic unpredictable stress (CUS in inducing depressive behaviors and associated molecular mechanism were investigated in rats. METHODS: Maternal deprivation was established by separating pups from their mothers for 6 hours daily from postnatal day 1 to day 14. Chronic unpredictable stress was established by water deprivation, elevated open platform, food deprivation, restraint stress and electric foot shock. The depressive behaviors were determined by use of sucrose preference test and forced swim test. RESULTS: Rats in MD/CUS group exhibited lower sucrose preference rate, longer immobility time, and lighter body weights than rats in other groups (MD/control, non-MD/CUS and non-MD/control group. Meanwhile, higher miR-504 expression and lower dopamine receptor D1 (DRD1 and D2 (DRD2 expression were observed in the nucleus accumbens of rats in the MD/CUS group than in the other three groups. MiR-504 expression correlated negatively with DRD1 gene expression and sucrose preference rate in the sucrose preference test, but correlated positively with immobility time in forced swim test. Both DRD2 mRNA and protein expression correlated negatively with immobility time in forced swim test. CONCLUSION: These results suggest that MD enhances behavioral vulnerability to stress during adulthood, which is associated with the upregulation of miR-504 and downregulation of DRD2 expression in the nucleus accumbens.

  15. Neurons of human nucleus accumbens

    Sazdanović Maja

    2011-01-01

    Full Text Available Background/Aim. Nucleus accumbens is a part of the ventral striatum also known as a drug active brain region, especially related with drug addiction. The aim of the study was to investigate the Golgi morphology of the nucleus accumbens neurons. Methods. The study was performed on the frontal and sagittal sections of 15 human brains by the Golgi Kopsch method. We classified neurons in the human nucleus accumbens according to their morphology and size into four types: type I - fusiform neurons; type II - fusiform neurons with lateral dendrite, arising from a part of the cell body; type III - pyramidal-like neuron; type IV - multipolar neuron. The medium spiny neurons, which are mostly noted regarding to the drug addictive conditions of the brain, correspond to the type IV - multipolar neurons. Results. Two regions of human nucleus accumbens could be clearly recognized on Nissl and Golgi preparations each containing different predominant neuronal types. Central part of nucleus accumbens, core region, has a low density of impregnated neurons with predominant type III, pyramidal-like neurons, with spines on secondary branches and rare type IV, multipolar neurons. Contrary to the core, peripheral region, shell of nucleus, has a high density of impregnated neurons predominantly contained of type I and type IV - multipolar neurons, which all are rich in spines on secondary and tertiary dendritic branches. Conclusion. Our results indicate great morphological variability of human nucleus accumbens neurons. This requires further investigations and clarifying clinical significance of this important brain region.

  16. Oxytocin in the nucleus accumbens shell reverses CRFR2-evoked passive stress-coping after partner loss in monogamous male prairie voles.

    Bosch, Oliver J; Dabrowska, Joanna; Modi, Meera E; Johnson, Zachary V; Keebaugh, Alaine C; Barrett, Catherine E; Ahern, Todd H; Guo, JiDong; Grinevich, Valery; Rainnie, Donald G; Neumann, Inga D; Young, Larry J

    2016-02-01

    Loss of a partner can have severe effects on mental health. Here we explore the neural mechanisms underlying increased passive stress-coping, indicative of depressive-like behavior, following the loss of the female partner in the monogamous male prairie vole. We demonstrate that corticotropin-releasing factor receptor 2 (CRFR2) in the nucleus accumbens shell mediates social loss-induced passive coping. Further, we show that partner loss compromises the oxytocin system through multiple mechanisms. Finally, we provide evidence for an interaction of the CRFR2 and oxytocin systems in mediating the emotional consequences of partner loss. Our results suggest that chronic activation of CRFR2 and suppression of striatal oxytocin signaling following partner loss result in an aversive emotional state that may share underlying mechanisms with bereavement. We propose that the suppression of oxytocin signaling is likely adaptive during short separations to encourage reunion with the partner and may have evolved to maintain long-term partnerships. Additionally, therapeutic strategies targeting these systems should be considered for treatment of social loss-mediated depression. PMID:26615473

  17. Deltorphin II enhances extracellular levels of dopamine in the nucleus accumbens via opioid receptor-independent mechanisms.

    Murakawa, K.; Hirose, N.; Takada, K.; Suzuki, T.; Nagase, H.; Cools, A.R.; Koshikawa, N.

    2004-01-01

    The effects of the delta2-opioid receptor agonist, deltorphin II, on extracellular levels of dopamine in the rat nucleus accumbens were investigated in awake animals by in vivo brain microdialysis. In agreement with previous studies, perfusion of deltorphin II (50.0 nmol) into the nucleus accumbens

  18. ENDOCANNABINOID 2-ARACHIDONOYLGLYCEROL SELF-ADMINISTRATION BY SPRAGUE-DAWLEY RATS AND STIMULATION OF IN VIVO DOPAMINE TRANSMISSION IN THE NUCLEUS ACCUMBENS SHELL

    Maria Antonietta eDe Luca

    2014-10-01

    Full Text Available 2-Arachidonoylglycerol (2-AG is the most potent endogenous ligand of brain cannabinoid CB1 receptors and is synthesized on demand from 2-arachidonate-containing phosphoinositides by the action of diacyglycerol lipase in response to increased intracellular calcium. Several studies indicate that the endocannabinoid (eCB system is involved in the mechanism of reward and that diverse drugs of abuse increase brain eCB levels. In addition, eCB are self-administered (SA by squirrel monkeys, and anandamide increases nucleus accumbens (NAc shell dopamine (DA in rats. To date, there is no evidence on the reinforcing effects of 2-AG and its effects on DA transmission in rodents. In order to fill this gap, we studied intravenous 2-AG SA and monitored the effect of 2-AG on extracellular DA in the NAc shell and core via microdialysis in male Sprague-Dawley rats. Rats were implanted with jugular catheters and trained to self-administer 2-AG (25g/kg/inf iv in single daily 1h sessions for 5 weeks under initial Fixed Ratio (FR 1 schedule. The ratio was subsequently increased to FR2. Active nose-poking increased from the 6th SA session (acquisition phase but no significant increase of nose-pokes was observed after FR2. When 2-AG was substituted for vehicle (25th SA session, extinction phase, rate responding, as well as number of injections, slowly decreased. When vehicle was replaced with 2-AG, SA behavior immediately recovered (reacquisition phase. The reinforcing effects of 2-AG in SA behavior were fully blocked by the CB1 receptor inverse agonist/antagonist rimonabant (1 mg/kg ip, 30 min before SA session. In the microdialysis studies, we observed that 2-AG (0.1-1.0 mg/kg iv preferentially stimulates NAc shell as compared to the NAc core. NAc shell DA increased by about 25% over basal value at the highest doses tested (0.5 and 1.0 mg/kg iv. The results obtained suggest that the eCB system, via 2-AG, plays an important role in reward.

  19. Alterations in blood glucose and plasma glucagon concentrations during deep brain stimulation in the shell region of the nucleus accumbens in rats

    Charlene eDiepenbroek

    2013-12-01

    Full Text Available Deep brain stimulation (DBS of the nucleus accumbens (NAc is an effective therapy for obsessive compulsive disorder (OCD and is currently under investigation as a treatment for eating disorders. DBS of this area is associated with altered food intake and pharmacological treatment of OCD is associated with the risk of developing type 2 diabetes. Therefore we examined if DBS of the NAc-shell (sNAc influences glucose metabolism. Male Wistar rats were subjected to DBS, or sham stimulation, for a period of one hour. To assess the effects of stimulation on blood glucose and glucoregulatory hormones, blood samples were drawn before, during and after stimulation. Subsequently, all animals were used for quantitative assessment of Fos immunoreactivity in the lateral hypothalamic area (LHA using computerized image analysis. DBS of the sNAc rapidly increased plasma concentrations of glucagon and glucose while sham stimulation and DBS outside the sNAc were ineffective. In addition, the increase in glucose was dependent on DBS intensity. In contrast, the DBS-induced increase in plasma corticosterone concentrations was independent of intensity and region, indicating that the observed DBS-induced metabolic changes were not due to corticosterone release. Stimulation of the sNAc with 200 μA increased Fos immunoreactivity in the LHA compared to sham or 100 μA stimulated animals. These data show that DBS of the sNAc alters glucose metabolism in a region- and intensity dependent manner in association with neuronal activation in the LHA. Moreover, these data illustrate the need to monitor changes in glucose metabolism during DBS-treatment of OCD patients.

  20. Alterations in blood glucose and plasma glucagon concentrations during deep brain stimulation in the shell region of the nucleus accumbens in rats.

    Diepenbroek, Charlene; van der Plasse, Geoffrey; Eggels, Leslie; Rijnsburger, Merel; Feenstra, Matthijs G P; Kalsbeek, Andries; Denys, Damiaan; Fliers, Eric; Serlie, Mireille J; la Fleur, Susanne E

    2013-01-01

    Deep brain stimulation (DBS) of the nucleus accumbens (NAc) is an effective therapy for obsessive compulsive disorder (OCD) and is currently under investigation as a treatment for eating disorders. DBS of this area is associated with altered food intake and pharmacological treatment of OCD is associated with the risk of developing type 2 diabetes. Therefore we examined if DBS of the NAc-shell (sNAc) influences glucose metabolism. Male Wistar rats were subjected to DBS, or sham stimulation, for a period of 1 h. To assess the effects of stimulation on blood glucose and glucoregulatory hormones, blood samples were drawn before, during and after stimulation. Subsequently, all animals were used for quantitative assessment of Fos immunoreactivity in the lateral hypothalamic area (LHA) using computerized image analysis. DBS of the sNAc rapidly increased plasma concentrations of glucagon and glucose while sham stimulation and DBS outside the sNAc were ineffective. In addition, the increase in glucose was dependent on DBS intensity. In contrast, the DBS-induced increase in plasma corticosterone concentrations was independent of intensity and region, indicating that the observed DBS-induced metabolic changes were not due to corticosterone release. Stimulation of the sNAc with 200 μA increased Fos immunoreactivity in the LHA compared to sham or 100 μA stimulated animals. These data show that DBS of the sNAc alters glucose metabolism in a region- and intensity- dependent manner in association with neuronal activation in the LHA. Moreover, these data illustrate the need to monitor changes in glucose metabolism during DBS-treatment of OCD patients. PMID:24339800

  1. Matrix-assisted laser desorption/ionization tissue profiling of secretoneurin in the nucleus accumbens shell from cocaine-sensitized rats

    Uys, Joachim D.; Grey, Angus C.; Wiggins, Armina; Schwacke, John H.; Schey, Kevin L.; Peter W Kalivas

    2010-01-01

    Proteins in the nucleus accumbens mediate many cocaine-induced behaviors. In an effort to measure changes in nucleus accumbens protein expression as potential biomarkers for addiction, coronal tissue sections were obtained from rats that developed behavioral sensitization after daily administration of cocaine, or from daily saline-treated controls. The tissue sections were subjected to matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) profiling and tissue imaging. For...

  2. MCH and apomorphine in combination enhance action potential firing of nucleus accumbens shell neurons in vitro

    F. Woodward Hopf; Taban Seif; Shinjae Chung; Olivier Civelli

    2013-01-01

    The MCH and dopamine receptor systems have been shown to modulate a number of behaviors related to reward processing, addiction, and neuropsychiatric conditions such as schizophrenia and depression. In addition, MCH and dopamine receptors can interact in a positive manner, for example in the expression of cocaine self-administration. A recent report (Chung et al., 2011a) showed that the DA1/DA2 dopamine receptor activator apomorphine suppresses pre-pulse inhibition, a preclinical model for so...

  3. Functional deficiency of MHC class I enhances LTP and abolishes LTD in the nucleus accumbens of mice.

    Mitsuhiro Edamura

    Full Text Available Major histocompatibility complex class I (MHCI molecules were recently identified as novel regulators of synaptic plasticity. These molecules are expressed in various brain areas, especially in regions undergoing activity-dependent synaptic plasticity, but their role in the nucleus accumbens (NAc is unknown. In this study, we investigated the effects of genetic disruption of MHCI function, through deletion of β2-microblobulin, which causes lack of cell surface expression of MHCI. First, we confirmed that MHCI molecules are expressed in the NAc core in wild-type mice. Second, we performed electrophysiological recordings with NAc core slices from wild-type and β2-microglobulin knock-out mice lacking cell surface expression of MHCI. We found that low frequency stimulation induced long-term depression in wild-type but not knock-out mice, whereas high frequency stimulation induced long-term potentiation in both genotypes, with a larger magnitude in knock-out mice. Furthermore, we demonstrated that knock-out mice showed more persistent behavioral sensitization to cocaine, which is a NAc-related behavior. Using this model, we analyzed the density of total AMPA receptors and their subunits GluR1 and GluR2 in the NAc core, by SDS-digested freeze-fracture replica labeling. After repeated cocaine exposure, the density of GluR1 was increased, but there was no change in total AMPA receptors and GluR2 levels in wild-type mice. In contrast, following repeated cocaine exposure, increased densities of total AMPA receptors, GluR1 and GluR2 were observed in knock-out mice. These results indicate that functional deficiency of MHCI enhances synaptic potentiation, induced by electrical and pharmacological stimulation.

  4. Cocaine-induced locomotor sensitization in rats correlates with nucleus accumbens activity on manganese-enhanced MRI.

    Perrine, Shane A; Ghoddoussi, Farhad; Desai, Kirtan; Kohler, Robert J; Eapen, Ajay T; Lisieski, Michael J; Angoa-Perez, Mariana; Kuhn, Donald M; Bosse, Kelly E; Conti, Alana C; Bissig, David; Berkowitz, Bruce A

    2015-11-01

    A long-standing goal of substance abuse research has been to link drug-induced behavioral outcomes with the activity of specific brain regions to understand the neurobiology of addiction behaviors and to search for drug-able targets. Here, we tested the hypothesis that cocaine produces locomotor (behavioral) sensitization that correlates with increased calcium channel-mediated neuroactivity in brain regions linked with drug addiction, such as the nucleus accumbens (NAC), anterior striatum (AST) and hippocampus, as measured using manganese-enhanced MRI (MEMRI). Rats were treated with cocaine for 5 days, followed by a 2-day drug-free period. The following day, locomotor sensitization was quantified as a metric of cocaine-induced neuroplasticity in the presence of manganese. Immediately following behavioral testing, rats were examined for changes in calcium channel-mediated neuronal activity in the NAC, AST, hippocampus and temporalis muscle, which was associated with behavioral sensitization using MEMRI. Cocaine significantly increased locomotor activity and produced behavioral sensitization compared with saline treatment of control rats. A significant increase in MEMRI signal intensity was determined in the NAC, but not AST or hippocampus, of cocaine-treated rats compared with saline-treated control rats. Cocaine did not increase signal intensity in the temporalis muscle. Notably, in support of our hypothesis, behavior was significantly and positively correlated with MEMRI signal intensity in the NAC. As neuronal uptake of manganese is regulated by calcium channels, these results indicate that MEMRI is a powerful research tool to study neuronal activity in freely behaving animals and to guide new calcium channel-based therapies for the treatment of cocaine abuse and dependence. PMID:26411897

  5. Matrix-assisted laser desorption/ionization tissue profiling of secretoneurin in the nucleus accumbens shell from cocaine-sensitized rats.

    Uys, Joachim D; Grey, Angus C; Wiggins, Armina; Schwacke, John H; Schey, Kevin L; Kalivas, Peter W

    2010-01-01

    Proteins in the nucleus accumbens mediate many cocaine-induced behaviors. In an effort to measure changes in nucleus accumbens protein expression as potential biomarkers for addiction, coronal tissue sections were obtained from rats that developed behavioral sensitization after daily administration of cocaine, or from daily saline-treated controls. The tissue sections were subjected to matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) profiling and tissue imaging. For profiling experiments, brain sections were manually spotted with matrix over the nucleus accumbens, a brain region known to regulate cocaine sensitization. Summed mass spectra (10,000 laser shots, grid) were acquired and spectra were aligned to reference peaks. Using bioinformatics tools, eight spectral features were found to be altered by cocaine treatment. Based on additional sequencing experiments with MALDI tandem MS and database searches of measured masses, secretoneurin (m/z 3653) was identified as having an increased expression. In addition, the distribution of m/z 3653 in the nucleus accumbens was determined by MALDI tissue imaging, and the increased expression of its precursor protein, secretogranin II, was verified by immunoblotting. PMID:19918966

  6. mTOR signalling in the nucleus accumbens shell is critical for augmented effect of TFF3 on behavioural response to cocaine.

    Luo, Yi-Xiao; Han, Hua; Shao, Juan; Gao, Yuan; Yin, Xi; Zhu, Wei-Li; Han, Ying; Shi, Hai-Shui

    2016-01-01

    Neuropeptides play important roles in modulating the rewarding value of abused drugs. Trefoil factor 3 (TFF3) was recently reported to modulate withdrawal syndrome of morphine, but the effects of TFF3 on the cocaine-induced behavioral changes are still elusive. In the present study, cocaine-induced hyperlocomotion and conditioned place preference (CPP) rat paradigms were provided to investigate the role of TFF3 in the reward response to cocaine. High-performance liquid chromatography (HPLC) analysis was used to analyse the dopamine concentration. The results showed that systemic TFF3 administration (0.1 mg/kg i.p.) significantly augmented cocaine- induced hyperlocomotion and CPP formation, without any effects on locomotor activity and aversive or rewarding effects per se. TFF3 significantly augmented the increment of the dopamine concentration in the NAc and the activity of the mTOR signalling pathway induced by acute cocaine exposure (10 mg/kg, i.p.) in the NAc shell, but not the core. The Intra-NAc shell infusion of rapamycin blocked TFF3-induced hyperactivity in cocaine-treatment rats. These findings indicated that TFF3 could potentiate behavioural response to cocaine, which may be associated with regulating dopamine concentration. Furthermore, the findings indicated that mTOR signalling pathway in the NAc shell is important for TFF3-induced enhancement on the cocaine-induced behavioral changes. PMID:27282818

  7. Dissociable Control of Impulsivity in Rats by Dopamine D2/3 Receptors in the Core and Shell Subregions of the Nucleus Accumbens

    Besson, Morgane; Belin, David; McNamara, Ruth; Theobald, David EH; Castel, Aude; Beckett, Victoria L.; Crittenden, Ben M.; Newman, Amy H.; Everitt, Barry J; Robbins, Trevor W.; Dalley, Jeffrey W.

    2010-01-01

    Previous research has identified the nucleus accumbens (NAcb) as an important brain region underlying inter-individual variation in impulsive behavior. Such variation has been linked to decreased dopamine (DA) D2/3 receptor availability in the ventral striatum of rats exhibiting spontaneously high levels of impulsivity on a 5-choice serial reaction time (5-CSRT) test of sustained visual attention. This study investigated the involvement of DA D2/3 receptors in the NAcb core (NAcbC) and the NA...

  8. Dielectric shell isolated and graphene shell isolated nanoparticle enhanced Raman spectroscopies and their applications.

    Li, Jian-Feng; Anema, Jason R; Wandlowski, Thomas; Tian, Zhong-Qun

    2015-12-01

    Surface-enhanced Raman scattering (SERS) is a powerful technique that provides fingerprint vibrational information with ultrahigh sensitivity. However, only a few metals (gold, silver and copper) yield a large SERS effect, and they must be rough at the nanoscale. Shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) was developed to overcome the long-standing materials and morphological limitations of SERS. It has already been applied in a variety of fields such as materials science, electrochemistry, surface science, catalysis, food safety and the life sciences. Here, the principles and applications of SHINERS are highlighted. To provide an understanding of the plasmonics involved, finite-difference time-domain (FDTD) calculations and single nanoparticle SHINERS experiments are reviewed. Next, various shell-isolated nanoparticle (SHIN) types are described. Then a number of applications are discussed. In the first application, SHINERS is used to characterize the adsorption processes of pyridine on Au(hkl) single-crystal electrode surfaces. Then, SHINERS' applicability to food inspection and cultural heritage science is demonstrated by the detection of parathion and fenthion pesticides, and Lauth's violet (thionine dye). Finally, graphene-isolated Au nanoparticles (GIANs) are shown to be effective for multimodal cell imaging, photothermal cancer therapy and photothermally-enhanced chemotherapy. SHINERS is a fast, simple and reliable method, suitable for application to many areas of science and technology. The concept of shell-isolation can also be applied to other surface-enhanced spectroscopies such as fluorescence, infrared absorption and sum frequency generation. PMID:26426491

  9. Multiple metallic-shell nanocylinders for surface-enhanced spectroscopes

    Chiu Kuo-Pin

    2011-01-01

    Full Text Available Abstract The optical properties of multiple dielectric-core-gold-shell nanocylinder pairs are investigated by two-dimensional finite difference time domain method. The core-shell cylinders are assumed to be of the same dimension and composition. For normal incidence, the diffraction spectra of multiple cylinder pairs contain the lightning-rod plasmon mode, and the electric field intensity is concentrated in the gap between the nanocylinder pairs in the infrared region. The resonance wavelength and local field enhancement of this plasmon mode can be tuned by varying the pair-distance between the pairs, the gap-distance between the pairs, and the optical constants of the dielectric-core and the surrounding medium. The results show that the multiple core-shell nanocylinder pair contains the plasmon mode same as that of the solid metallic cylinder pairs at the long wavelength part of the spectrum. The large electric field intensity in the infrared region at long wavelength makes multiple core-shell cylinders as ideal candidates for surface-enhanced spectroscopes.

  10. Enhanced efficiency of a fluorescing nanoparticle with a silver shell

    Choy, Wallace C H; Chen Xuewen [Department of Electrical and Electronic Engineering, University of Hong Kong, Pokfulam Road (Hong Kong); He Sailing [Centre for Optical and Electromagnetic Research, Zhejiang University, Zhijingang campus, Hangzhou 310058 (China)], E-mail: chchoy@eee.hku.hk

    2009-09-01

    Spontaneous emission (SE) rate and the fluorescence efficiency of a bare fluorescing nanoparticle (NP) and the NP with a silver nanoshell are analyzed rigorously by using a classical electromagnetic approach with the consideration of the nonlocal effect of the silver nano-shell. The dependences of the SE rate and the fluorescence efficiency on the core-shell structure are carefully studied and the physical interpretations of the results are addressed. The results show that the SE rate of a bare NP is much slower than that in the infinite medium by almost an order of magnitude and consequently the fluorescence efficiency is usually low. However, by encapsulating the NP with a silver shell, highly efficient fluorescence can be achieved as a result of a large Purcell enhancement and high out-coupling efficiency (OQE) for a well-designed core-shell structure. We also show that a higher SE rate may not offer a larger fluorescence efficiency since the fluorescence efficiency not only depends on the internal quantum yield but also the OQE.

  11. Roles of dopaminergic innervation of nucleus accumbens shell and dorsolateral caudate-putamen in cue-induced morphine seeking after prolonged abstinence and the underlying D1- and D2-like receptor mechanisms in rats

    Gao, Jun; Li, Yonghui; Zhu, Ning; Brimijoin, Stephen; Sui, Nan

    2013-01-01

    Drug-associated cues can elicit relapse to drug seeking after abstinence. Studies with extinction–reinstatement models implicate dopamine (DA) in the nucleus accumbens shell (NAshell) and dorsolateral caudate-putamen (dlCPu) in cocaine seeking. However, less is known about their roles in cue-induced opiate seeking after prolonged abstinence. Using a morphine self-administration and abstinence–relapse model, we explored the roles of NAshell and dlCPu DA and the D1/D2-like receptor mechanisms underlying morphine rewarding and/or seeking. Acquisition of morphine self-administration was examined following 6-Hydroxydopamine hydrobromide (6-OHDA) lesions of the NAshell and dlCPu. For morphine seeking, rats underwent 3 weeks’ morphine self-administration followed by 3 weeks’ abstinence from morphine and the training environment. Prior to testing, 6-OHDA, D1 antagonist SCH23390, or D2 antagonist eticlopride was locally injected; then rats were exposed to morphine-associated contextual and discrete cues. Results show that acquisition of morphine self-administration was inhibited by NAshell (not dlCPu) lesions, while morphine seeking was attenuated by lesions of either region, by D1 (not D2) receptor blockade in NAshell, or by blockade of either D1 or D2 receptors in dlCPu. These data indicate a critical role of dopaminergic transmission in the NAshell (via D1-like receptors) and dlCPu (via D1- and D2-like receptors) in morphine seeking after prolonged abstinence. PMID:23151613

  12. Selective D3 Receptor Antagonist SB-277011-A Potentiates the Effect of Cocaine on Extracellular Dopamine in the Nucleus Accumbens: a Dual Core-Shell Voltammetry Study in Anesthetized Rats

    Francesca Formenti

    2008-11-01

    Full Text Available Dopamine (DA D3 receptors have been associated with drug intake and abuse and selectively distribute in the brain circuits responding to drug administration. Here we examined the effects of an acute systemic administration of cocaine (15 mg/kg alone or preceded by treatment with the selective D3 receptor antagonist SB-277011-A (10 mg/kg on DA levels concurrently in the rat nucleus accumbens shell and core sub-regions (NAcshell and NAccore, respectively. It is shown that cocaine increases extracellular DA in both compartments and that blocking D3 receptors with SB-277011-A, although the latter is devoid of dopaminergic effects per se, potentiates these effects. No differences in the amplitude of the response were observed between NAcshell and NAccore compartments, though the dopaminergic response in the NAcshell was transient whereas that in the NAccore rose slowly to reach a plateau. These results demonstrate the feasibility to use multiprobe voltammetry to measure discrete monoaminergic responses in discrete areas of the brain and confirm the effect of D3 receptors antagonist at modifying the neurochemical effects of cocaine.

  13. Repeated cocaine administration decreases calcineurin (PP2B) but enhances DARPP-32 modulation of sodium currents in rat nucleus accumbens neurons.

    Hu, Xiu-Ti; Ford, Kerstin; White, Francis J

    2005-05-01

    Our previous studies have demonstrated that repeated cocaine (COC) administration reduces voltage-sensitive sodium and calcium currents (I(Na) or VSSCs and I(Ca) or VSCCs, respectively) in medium spiny nucleus accumbens (NAc) neurons of rats. The present findings further indicate that chronic COC-induced I(Na) reduction in NAc neurons is regulated by decreased dephosphorylation and enhanced phosphorylation of Na(+) channels. Whole-cell voltage-clamp recordings revealed that dephosphorylation of Na(+) channels by calcineurin (CaN) enhanced I(Na), while inhibition of protein phosphatase 1 (PP1) by phosphorylated dopamine- and cAMP-regulated phosphoprotein (M(r)=32 kDa) (DARPP-32) at the site of threonine 34 (p-Thr.34-DARPP-32) suppressed I(Na), in freshly dissociated NAc neurons of saline-pretreated rats. However, the effects of CaN on enhancing I(Na) were significantly attenuated, and the action of p-Thr.34-DARPP-32 to decrease I(Na) was mimicked, although not potentiated, by repeated COC pretreatment. Dephosphorylation of Na(+) channels by PP1 also enhanced I(Na), but this effect of PP1 on I(Na) was not apparently affected by repeated COC administration. Western blot analysis indicates that the protein levels of CaN and DARPP-32 were significantly decreased and increased, respectively, while the PP1 levels were unchanged, in the COC-withdrawn NAc as compared to saline-pretreated controls. Combined with previous findings, our results indicate that both CaN and PP1 modulate the increase in I(Na) via enhancing dephosphorylation, while p-Thr.34-DARPP-32 reduces I(Na) by inhibiting PP1-induced dephosphorylation, thereby stabilizing the phosphorylation state, of Na(+) channels in NAc neurons. They also suggest that chronic COC-induced I(Na) reduction may be attributed to a reduction in Ca(2+) signaling, which disrupts the physiological balance of phosphorylation and dephosphorylation of Na(+) channels. PMID:15726118

  14. Enhanced upregulation of CRH mRNA expression in the nucleus accumbens of male rats after a second injection of methamphetamine given thirty days later.

    Jean Lud Cadet

    Full Text Available Methamphetamine (METH is a widely abused amphetamine analog. Few studies have investigated the molecular effects of METH exposure in adult animals. Herein, we determined the consequences of an injection of METH (10 mg/kg on transcriptional effects of a second METH (2.5 mg/kg injection given one month later. We thus measured gene expression by microarray analyses in the nucleus accumbens (NAc of 4 groups of rats euthanized 2 hours after the second injection: saline-pretreated followed by saline-challenged (SS or METH-challenged (SM; and METH-pretreated followed by saline-challenged (MS or METH-challenged (MM. Microarray analyses revealed that METH (2.5 mg/kg produced acute changes (1.8-fold; P<0.01 in the expression of 412 (352 upregulated, 60 down-regulated transcripts including cocaine and amphetamine regulated transcript, corticotropin-releasing hormone (Crh, oxytocin (Oxt, and vasopressin (Avp that were upregulated. Injection of METH (10 mg/kg altered the expression of 503 (338 upregulated, 165 down-regulated transcripts measured one month later (MS group. These genes also included Cart and Crh. The MM group showed altered expression of 766 (565 upregulated, 201 down-regulated transcripts including Avp, Cart, and Crh. The METH-induced increased Crh expression was enhanced in the MM group in comparison to SM and MS groups. Quantitative PCR confirmed the METH-induced changes in mRNA levels. Therefore, a single injection of METH produced long-lasting changes in gene expression in the rodent NAc. The long-term increases in Crh, Cart, and Avp mRNA expression suggest that METH exposure produced prolonged activation of the endogenous stress system. The METH-induced changes in oxytocin expression also suggest the possibility that this neuropeptide might play a significant role in the neuroplastic and affiliative effects of this drug.

  15. Intra-accumbens baclofen, but not muscimol, increases second order instrumental responding for food reward in rats.

    Kim G T Pulman

    Full Text Available Stimulation of either GABA(A or GABA(B receptors within the nucleus accumbens shell strongly enhances food intake in rats. However the effects of subtype-selective stimulation of GABA receptors on instrumental responses for food reward are less well characterized. Here we contrast the effects of the GABA(A receptor agonist muscimol and GABA(B receptor agonist baclofen on instrumental responding for food using a second order reinforcement schedule. Bilateral intra-accumbens administration of baclofen (220-440 pmol stimulated responding but a higher dose (660 pmol induced stereotyped oral behaviour that interfered with responding. Baclofen (220-660 pmol also stimulated intake of freely available chow. Muscimol (220-660 pmol was without effect on responding for food on this schedule but did stimulate intake of freely available chow. Unilateral administration of either baclofen or muscimol (220 pmol induced similar patterns of c-fos immunoreactivity in several hypothalamic sites but differed in its induction in the central nucleus of the amygdala. We conclude that stimulation of GABA(A or GABA(B receptors in the nucleus accumbens shell of rats produces clearly distinguishable effects on operant responding for food.

  16. Enhancing the Communication Channel Through Secure Shell And Irrational DES

    S.R.M.Krishna,

    2011-03-01

    Full Text Available As the internet grows in popularity and therefore also in size more and more transmission takes place mainly because the technology is more readily available and applications have become more user friendlyallowing entry to less sophisticated user over a broad spectrum.most data transfer are mainly text based not secure and vulnerable to various forms of security risks. So the model that uses SSH for securing channel like intranet/internet which provides client authentication encryption and decryption with high degree of security by transferring the data in an encrypted format, up on this model enhances the efficiency of data transmission by encrypting or decrypting the data with irrational DES.DES is a cryptographic standard however,the applications of it limited because of small key space based on irrational number.Moreover the permutation controlled by data can be performed at high speed in generic cpu.this scheme also expands the key space without costing more to run.and also finally through the combination of secure shell(ssh and irrational DES not only enhances the security of communication channel.it also provides varius applications like remote user creation,remote user deletion,remote command execution,remote system shutdown ,remote file transfer applications in an highly secure manner.

  17. Core–shell nanoparticles and enhanced polarization in polymer based nanocomposite dielectrics

    We present a detailed study of the evolution and nature of metallic core–oxide shell particles and the role of nanostructure in the physics of enhanced polarization in polymer-nanocomposite (PNC) based dielectrics. Nylon-6 based PNCs consisting of aluminium (core)–aluminium oxide (shell) nanoparticles were fabricated by a vacuum deposition technique. Their resulting high polarizability was closely related to the formation and chemistry of the core–shell structure that was revealed by transmission electron microscopy to comprise a highly-defective, strained and non-stoichiometric semi-crystalline/amorphous Al-oxide shell. (paper)

  18. Relationship of Dopamine of the Nucleus Accumbens with Intra-infralimbic Apomorphine Microinjection

    Abbas Alimoradian; Javad Sajedianfard; Faegheh Baha-aldini Beigy; Mohammad Reza Panjehshahin; Ali Akbar Owji

    2013-01-01

      Objective(s): The dopamine level of the nucleus accumbens changes during some stereotyped behaviors. To study dopamine level of the nucleus accumbens in intra infralimbic apomorphine-induced climbing, microdialysis probes were implanted into the nucleus accumbens shell of male Sprague Dawley rats weighting 275–400 g.   Materials and Methods: The rats were divided into two groups (apomorphine and control) of least eleven rats in each group. Apomorphine at dose of 5 μg/0.5 μl or its vehicle w...

  19. Metal enhanced fluorescence in rare earth doped plasmonic core-shell nanoparticles

    Derom, S.; Berthelot, A.; Pillonnet, A.; Benamara, O.; Jurdyc, A. M.; Girard, C.; Colas des Francs, G.

    2013-12-01

    We theoretically and numerically investigate metal enhanced fluorescence of plasmonic core-shell nanoparticles doped with rare earth (RE) ions. Particle shape and size are engineered to maximize the average enhancement factor (AEF) of the overall doped shell. We show that the highest enhancement (11 in the visible and 7 in the near-infrared) is achieved by tuning either the dipolar or the quadrupolar particle resonance to the rare earth ion’s excitation wavelength. Additionally, the calculated AEFs are compared to experimental data reported in the literature, obtained in similar conditions (plasmon mediated enhancement) or when a metal-RE energy transfer mechanism is involved.

  20. Metal enhanced fluorescence in rare earth doped plasmonic core–shell nanoparticles

    We theoretically and numerically investigate metal enhanced fluorescence of plasmonic core–shell nanoparticles doped with rare earth (RE) ions. Particle shape and size are engineered to maximize the average enhancement factor (AEF) of the overall doped shell. We show that the highest enhancement (11 in the visible and 7 in the near-infrared) is achieved by tuning either the dipolar or the quadrupolar particle resonance to the rare earth ion’s excitation wavelength. Additionally, the calculated AEFs are compared to experimental data reported in the literature, obtained in similar conditions (plasmon mediated enhancement) or when a metal–RE energy transfer mechanism is involved. (paper)

  1. Shell-isolated nanoparticle-enhanced fluorescence (SHINEF) of CdTe quantum dots

    We report shell-isolated nanoparticle-enhanced fluorescence (SHINEF) of CdTe quantum dots. Enhanced spectra are obtained after Ag SHINs were spread onto homogenous CdTe quantum dot/polyelectrolyte layer-by-layer (LbL) films on quartz. The thin silica shell of the SHINs effectively isolates the Ag cores, preventing short-range quenching to the metal and enabling plasmon enhancement of the quantum dot fluorescence (ca. 35 fold). - Highlights: • Shell-Isolated Nanoparticles-Enhanced Fluorescence (SHINEF). • Synthesis of CdTe quantum dot. • Layer-by-Layer technique for thin films preparation. • Different size of CdTe quantum dots. • Size effect of quantum dots in enhanced factor

  2. Shell-isolated nanoparticle-enhanced fluorescence (SHINEF) of CdTe quantum dots

    Ramírez-Maureira, Monica; Vargas, Víctor C [Facultad de Ciencias, Universidad de Chile, Santiago, 7800003 (Chile); Riveros, Ana [Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, 7803287 (Chile); Goulet, Paul J.G. [Department of Chemistry and Biomolecular Science, Clarkson University, Potsdam, NY, 13699-5810 (United States); Osorio-Román, Igor O., E-mail: iosorior@uwindsor.ca [Facultad de Química, Pontificia Universidad Católica de Chile, Santiago, 7820436 (Chile)

    2015-02-01

    We report shell-isolated nanoparticle-enhanced fluorescence (SHINEF) of CdTe quantum dots. Enhanced spectra are obtained after Ag SHINs were spread onto homogenous CdTe quantum dot/polyelectrolyte layer-by-layer (LbL) films on quartz. The thin silica shell of the SHINs effectively isolates the Ag cores, preventing short-range quenching to the metal and enabling plasmon enhancement of the quantum dot fluorescence (ca. 35 fold). - Highlights: • Shell-Isolated Nanoparticles-Enhanced Fluorescence (SHINEF). • Synthesis of CdTe quantum dot. • Layer-by-Layer technique for thin films preparation. • Different size of CdTe quantum dots. • Size effect of quantum dots in enhanced factor.

  3. Palladium-platinum core-shell icosahedra with substantially enhanced activity and durability towards oxygen reduction

    Wang, Xue; Choi, Sang-Il; Roling, Luke T.; Luo, Ming; Ma, Cheng; Zhang, Lei; Chi, Miaofang; Liu, Jingyue; Xie, Zhaoxiong; Herron, Jeffrey A.; Mavrikakis, Manos; Xia, Younan

    2015-07-01

    Conformal deposition of platinum as ultrathin shells on facet-controlled palladium nanocrystals offers a great opportunity to enhance the catalytic performance while reducing its loading. Here we report such a system based on palladium icosahedra. Owing to lateral confinement imposed by twin boundaries and thus vertical relaxation only, the platinum overlayers evolve into a corrugated structure under compressive strain. For the core-shell nanocrystals with an average of 2.7 platinum overlayers, their specific and platinum mass activities towards oxygen reduction are enhanced by eight- and sevenfold, respectively, relative to a commercial catalyst. Density functional theory calculations indicate that the enhancement can be attributed to the weakened binding of hydroxyl to the compressed platinum surface supported on palladium. After 10,000 testing cycles, the mass activity of the core-shell nanocrystals is still four times higher than the commercial catalyst. These results demonstrate an effective approach to the development of electrocatalysts with greatly enhanced activity and durability.

  4. Fast Ignition Thermonuclear Fusion: Enhancement of the Pellet Gain by the Colossal-Magnetic-Field Shells

    Stefan, V. Alexander

    2013-10-01

    The fast ignition fusion pellet gain can be enhanced by a laser generated B-field shell. The B-field shell, (similar to Earth's B-field, but with the alternating B-poles), follows the pellet compression in a frozen-in B-field regime. A properly designed laser-pellet coupling can lead to the generation of a B-field shell, (up to 100 MG), which inhibits electron thermal transport and confines the alpha-particles. In principle, a pellet gain of few-100s can be achieved in this manner. Supported in part by Nikola Tesla Labs, Stefan University, 1010 Pearl, La Jolla, CA 92038-1007.

  5. Enhanced photocatalytic activity of titanium dioxide by nut shell carbon

    Shi Xiaoliang, E-mail: sxl@whut.edu.cn [School of Mechanical and Electronic Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China); State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China); Wang Sheng; Dong Xuebin [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China); Zhang Qiaoxin [School of Mechanical and Electronic Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China); State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China)

    2009-08-15

    Nut shell carbon (NSC)-nanotitanium dioxide (TiO{sub 2}) composites were prepared by sol-gel method. Photocatalytic activity on degradation of dye Rhodamine B was studied. X-ray diffraction, field emission scanning electron microscopy, Brunauer-Emmett-Teller surface area, pore size distribution, ultraviolet-vis light absorption spectrum, and photoluminescence spectrum were carried out to characterize the composite catalyst. The results indicated that the photocatalytic activity of NSC-nano-TiO{sub 2} composites was much higher than P25 (Degussa). NSC could greatly absorb the organic substance and oxygen of solution because of its large surface area.

  6. In vitro hyperthermia with improved colloidal stability and enhanced SAR of magnetic core/shell nanostructures.

    Patil, R M; Thorat, N D; Shete, P B; Otari, S V; Tiwale, B M; Pawar, S H

    2016-02-01

    Magnetic core/shell nanostructures of Fe3O4 nanoparticles coated with oleic acid and betaine-HCl were studied for their possible use in magnetic fluid hyperthermia (MFH). Their colloidal stability and heat induction ability were studied in different media viz. phosphate buffer solution (PBS), saline solution and glucose solution with different physiological conditions and in human serum. The results showed enhanced colloidal stability in these media owing to their high zeta potential values. Heat induction studies showed that specific absorption rates (SAR) of core/shells were 82-94W/g at different pH of PBS and concentrations of NaCl and glucose. Interestingly, core/shells showed 78.45±3.90W/g SAR in human serum. The cytotoxicity of core/shells done on L929 and HeLa cell lines using 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide and trypan blue dye exclusion assays showed >89% and >80% cell viability for 24 and 48h respectively. Core/shell structures were also found to be very efficient for in vitro MFH on cancer cell line. About 95% cell death was occurred in 90min after hyperthermia treatment. The mechanism of cell death was found to be elevated ROS generation in cells after exposure to core/shells in external magnetic field. This study showed that these core/shells have a great potential to be used in in vivo MFH. PMID:26652424

  7. Enhanced Photocatalytic H2 Production in Core-Shell Engineered Rutile TiO2.

    Yang, Yongqiang; Liu, Gang; Irvine, John T S; Cheng, Hui-Ming

    2016-07-01

    A rationally designed crystalline Ti(3+) core/amorphous Ti(4+) shell configuration can reverse the population disparity between holes and electrons reaching the surface of microsized rutile TiO2 photocatalyst, thus significantly enhancing its photocatalytic activity by two orders of magnitude in terms of the hydrogen production rate under the irradiation of UV-vis light. PMID:27159036

  8. Enhanced Ethanol Gas Sensing Properties of SnO2-Core/ZnO-Shell Nanostructures

    T. Tharsika

    2014-08-01

    Full Text Available An inexpensive single-step carbon-assisted thermal evaporation method for the growth of SnO2-core/ZnO-shell nanostructures is described, and the ethanol sensing properties are presented. The structure and phases of the grown nanostructures are investigated by field-emission scanning electron microscopy (FESEM, transmission electron microscopy (TEM and X-ray diffraction (XRD techniques. XRD analysis indicates that the core-shell nanostructures have good crystallinity. At a lower growth duration of 15 min, only SnO2 nanowires with a rectangular cross-section are observed, while the ZnO shell is observed when the growth time is increased to 30 min. Core-shell hierarchical nanostructures are present for a growth time exceeding 60 min. The growth mechanism for SnO2-core/ZnO-shell nanowires and hierarchical nanostructures are also discussed. The sensitivity of the synthesized SnO2-core/ZnO-shell nanostructures towards ethanol sensing is investigated. Results show that the SnO2-core/ZnO-shell nanostructures deposited at 90 min exhibit enhanced sensitivity to ethanol. The sensitivity of SnO2-core/ZnO-shell nanostructures towards 20 ppm ethanol gas at 400 °C is about ~5-times that of SnO2 nanowires. This improvement in ethanol gas response is attributed to high active sensing sites and the synergistic effect of the encapsulation of SnO2 by ZnO nanostructures.

  9. Numerical simulation of heat transfer enhancement in shell side of shell-and-tube heat exchanger with leading type shutter baffles

    For overcoming the contradiction between the performance improvement and fluid flow resistance increase in shell-and-tube heat exchanger, a new concept of 'Sideling Flow' in shell side is presented, and a type of new high efficiency energy saving shell-and-tube heat exchanger with leading type shutter baffles in shell side, sideling flow heat exchanger is invented. Besides, the 'Field Synergy Principle' is adopted to analyze its heat transfer enhancement mechanism, and it is indicated that there is the perfect synergy between the velocity field and temperature grads field in shell side of this type of new heat exchanger. Effects of the structure parameters on the fluid flow and heat transfer are investigated through numerical simulation, and the numerical results are in good agreement with the experimental data. (authors)

  10. Shell-isolated nanoparticle-enhanced Raman spectroscopy: principle and applications (Presentation Recording)

    Li, Jian-Feng; Tian, Zhong-Qun

    2015-08-01

    Surface-enhanced Raman spectroscopy (SERS) is a powerful technique that yields fingerprint vibrational information with ultra-high sensitivity. However, only roughened Ag, Au and Cu surfaces can generate strong SERS effect. The lack of materials and morphology generality has severely limited the breadth of SERS practical applications on surface science, electrochemistry and catalysis. Shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) was therefore invented to break the long-standing limitation of SERS. In SHINERS, Au@SiO2 core-shell nanoparticles were rationally designed. The gold core acts as plasmonic antenna and encapsulated by an ultra-thin, uniform and pinhole-free silica shell, can provide high electromagnetic field to enhance the Raman signals of probed molecules. The inert silica shell acts as tunneling barrier prevents the core from interacting with the environment. SHINERS has already been applied to a number of challenging systems, such as hydrogen and CO on Pt(hkl) and Rh(hkl), which can't be realized by traditional SERS. Combining with electrochemical methods, we has investigated the adsorption processes of pyridine at the Au(hkl) single crystal/solution interface, and in-situ monitored the surface electro-oxidation at Au(hkl) electrodes. These pioneering studies demonstrate convincingly the ability of SHINERS in exploring correlations between structure and reactivity as well as in monitoring intermediates at the interfaces. SHINERS was also explored from semiconductor surface for industry, to living bacteria for life science, and to pesticide residue detection for food safety. The concept of shell-isolated nanoparticle-enhancement is being applied to other spectroscopies such as infrared absorption, sum frequency generation and fluorescence. Jian-Feng Li et al., Nature, 2010, 464, 392-395.

  11. Heterogeneous core/shell fluoride nanocrystals with enhanced upconversion photoluminescence for in vivo bioimaging

    Hao, Shuwei; Yang, Liming; Qiu, Hailong; Fan, Rongwei; Yang, Chunhui; Chen, Guanying

    2015-06-01

    We report on heterogeneous core/shell CaF2:Yb3+/Ho3+@NaGdF4 nanocrystals of 17 nm with efficient upconversion (UC) photoluminescence (PL) for in vivo bioimaging. Monodisperse core/shell nanostructures were synthesized using a seed-mediated growth process involving two quite different approaches of liquid-solid-solution and thermal decomposition. They exhibit green emission with a sharp band around 540 nm when excited at ~980 nm, which is about 39 times brighter than the core CaF2:Yb3+/Ho3+ nanoparticles. PL decays at 540 nm revealed that such an enhancement arises from efficient suppression of surface-related deactivation from the core nanocrystals. In vivo bioimaging employing water-dispersed core/shell nanoparticles displayed high contrast against the background.We report on heterogeneous core/shell CaF2:Yb3+/Ho3+@NaGdF4 nanocrystals of 17 nm with efficient upconversion (UC) photoluminescence (PL) for in vivo bioimaging. Monodisperse core/shell nanostructures were synthesized using a seed-mediated growth process involving two quite different approaches of liquid-solid-solution and thermal decomposition. They exhibit green emission with a sharp band around 540 nm when excited at ~980 nm, which is about 39 times brighter than the core CaF2:Yb3+/Ho3+ nanoparticles. PL decays at 540 nm revealed that such an enhancement arises from efficient suppression of surface-related deactivation from the core nanocrystals. In vivo bioimaging employing water-dispersed core/shell nanoparticles displayed high contrast against the background. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02287h

  12. Relationship of Dopamine of the Nucleus Accumbens with Intra-infralimbic Apomorphine Microinjection

    Abbas Alimoradian

    2013-06-01

    Full Text Available   Objective(s: The dopamine level of the nucleus accumbens changes during some stereotyped behaviors. To study dopamine level of the nucleus accumbens in intra infralimbic apomorphine-induced climbing, microdialysis probes were implanted into the nucleus accumbens shell of male Sprague Dawley rats weighting 275–400 g.   Materials and Methods: The rats were divided into two groups (apomorphine and control of least eleven rats in each group. Apomorphine at dose of 5 μg/0.5 μl or its vehicle was microinjected into the infralimbic in apomorphine and control groups respectively. Then, changes in dopamine levels in the nucleus accumbens shell were monitored. The concentration of dopamine was measured by High-Performance Liquid Chromatography-Electochemical (HPLC-ECD. Finally, the stereotyped behaviors were recorded. Results: The mean of dopamine levels for all of after microinjection period in control and drug groups were 450% and 150% respectively compared to those of before microinjection period. However, there was no significant difference between groups of apomorphine and control. In addition, the return of dopamine level to the baseline was faster in apomorphine group than the control group. Conclusion: The intra infralimbic apomorphine -induced climbing at dose of 5 μg/0.5 μl was not modulated via the increase of dopamine level in the nucleus accumbens area.

  13. Enhanced dopamine D1 and BDNF signaling in the adult dorsal striatum but not nucleus accumbens of prenatal cocaine treated mice

    Thomas F. Tropea

    2011-12-01

    Full Text Available Previous work from our group and others utilizing animal models have demonstrated long lasting structural and functional alterations in the meso-cortico-striatal dopamine pathway following prenatal cocaine treatment. We have shown that prenatal cocaine treatment results in augmented D1 -induced cyclic AMP (cAMP and cocaine-induced immediate-early gene expression in the striatum of adult mice. In this study we further examined basal as well as cocaine or D1-induced activation of a set of molecules known to be mediators of neuronal plasticity following psychostimulant treatment, with emphasis in the dorsal striatum (Str and nucleus accumbens (NAc of adult mice exposed to cocaine in utero. Basally, in the striatum of prenatal cocaine treated (PCOC mice there were significantly higher levels of a number of the transcription factors studied. Following acute administration of cocaine (15 mg/kg, i.p. or D1 agonist (SKF 82958; 1 mg/kg, i.p. there were significantly higher levels of Ser133 P-CREB, Thr34 P-DARPP-32, and Thr202/Tyr204 P-ERK2 in the Str, that were significantly augmented in PCOC mice. In sharp contrast, in the NAc of those mice, we found increased P-CREB and P-ERK2 in PSAL mice, a response that was not evident in PCOC mice. Examination of Ser 845 P-GluA1 revealed increased levels in PSAL mice, but significantly decreased levels in PCOC mice in both the Str and NAc following acute administration of cocaine or D1 agonist. We also found significantly higher levels of the BDNF precursor, pro-BDNF and one of its receptors, TrkB in the Str of PCOC mice. These results suggest a persistent up-regulation of molecules critical to D1 and BDNF signaling in the Str of adult mice exposed to cocaine in utero. These molecular adaptations may underlie components of the behavioral deficits evident in exposed animals and a subset of exposed humans, and may represent a therapeutic target for ameliorating aspects of the prenatal cocaine-induced phenotype.

  14. Photo-physical properties enhancement of bare and core-shell quantum dots

    Mumin, Md Abdul, E-mail: pcharpentier@eng.uwo.ca; Akhter, Kazi Farida, E-mail: pcharpentier@eng.uwo.ca; Charpentier, Paul A., E-mail: pcharpentier@eng.uwo.ca [Chemical and Biochemical Engineering, Western University, London Ontario (Canada)

    2014-03-31

    Semiconductor nanocrystals (NCs) (also known as quantum dots, QDs) have attracted immense attention for their size-tunable optical properties that makes them impressive candidates for solar cells, light emitting devices, lasers, as well as biomedical imaging. However monodispersity, high and consistent photoluminescence, photostability, and biocompatibility are still major challenges. This work focuses on optimizing the photophysical properties and biocompatibility of QDs by forming core-shell nanostructures and their encapsulation by a carrier. Highly luminescent CdS and CdS-ZnS core-shell QDs with 5 nm sizes were synthesized using a facile approach based on pyrolysis of the single molecule precursors. After capping the CdS QDs with a thin layer of ZnS to reduce toxicity, the photoluminescence and photostability of the core-shell QDs was significantly enhanced. To make both the bare and core/shell structure QDs more resistant against photochemical reactions, a mesoporous silica layer was grown on the QDs through a reverse microemulsion technique based on hydrophobic interaction. This encapsulation enhanced the quantum yield and photostability compared to the bare QDs by providing much stronger resistance to oxidation and Oswald ripening of QDs. Encapsulation also improved biocompatibility of QDs that was evaluated with human umbilical vein endothelial cell lines (HUVEC)

  15. Single particle optical investigation of gold shell enhanced upconverted fluorescence emission

    Green, Kory; Lim, Shuang Fang; Hallen, Hans

    2014-03-01

    Upconverting nanoparticles (UCNPs) excited in the near IR offer novel advantages as fluorescent contrast agents, allowing for background free bio-imaging. However, their fluorescence brightness is hampered by low quantum efficiency due to the low absorption cross section of Ytterbium and Erbium ions in the near IR. We enhance the efficiency of these particles by investigating the plasmonic coupling of 30nm diameter core NaYF4: Yb, Er upconverting particles (UCNPs) with a gold shell coating. An enhancement of green emission by a factor of five and a three times overall increase in emission intensity has been achieved for single particle spectra. UV-Vis absorption has confirmed the surface plasmon resonance (SPR) of the gold shell to the near IR and transmission electron microscope (TEM) images demonstrates successful growth of a gold shell around the upconversion particle. Time-resolved spectroscopy shows that gold shell coupling changes the lifetime of the energy levels of the Erbium ion that are relevant to the emission process.

  16. Octahedral core–shell cuprous oxide/carbon with enhanced electrochemical activity and stability as anode for lithium ion batteries

    Xiang, Jiayuan, E-mail: xjyzju@aliyun.com [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); Chen, Zhewei [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); Hangzhou No. 2 High School, Hangzhou 310053 (China); Wang, Jianming [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China)

    2015-10-15

    Highlights: • Core–shell octahedral Cu{sub 2}O/C is prepared by a one-step method. • Carbon shell is amorphous and uniformly decorated at the Cu{sub 2}O octahedral core. • Core–shell Cu{sub 2}O/C exhibits markedly enhanced capability and reversibility. • Carbon shell provides fast ion/electron transfer channel. • Core–shell structure is stable during cycling. - Abstract: Core–shell Cu{sub 2}O/C octahedrons are synthesized by a simple hydrothermal method with the help of carbonization of glucose, which reduces Cu(II) to Cu(I) at low temperature and further forms carbon shell coating at high temperature. SEM and TEM images indicate that the carbon shell is amorphous with thickness of ∼20 nm wrapping the Cu{sub 2}O octahedral core perfectly. As anode of lithium ion batteries, the core–shell Cu{sub 2}O/C composite exhibits high and stable columbic efficiency (98%) as well as a reversible capacity of 400 mAh g{sup −1} after 80 cycles. The improved electrochemical performance is attributed to the novel core–shell structure, in which the carbon shell reduces the electrode polarization and promotes the charge transfer at active material/electrolyte interface, and also acts as a stabilizer to keep the octahedral structure integrity during discharge–charge processes.

  17. Octahedral core–shell cuprous oxide/carbon with enhanced electrochemical activity and stability as anode for lithium ion batteries

    Highlights: • Core–shell octahedral Cu2O/C is prepared by a one-step method. • Carbon shell is amorphous and uniformly decorated at the Cu2O octahedral core. • Core–shell Cu2O/C exhibits markedly enhanced capability and reversibility. • Carbon shell provides fast ion/electron transfer channel. • Core–shell structure is stable during cycling. - Abstract: Core–shell Cu2O/C octahedrons are synthesized by a simple hydrothermal method with the help of carbonization of glucose, which reduces Cu(II) to Cu(I) at low temperature and further forms carbon shell coating at high temperature. SEM and TEM images indicate that the carbon shell is amorphous with thickness of ∼20 nm wrapping the Cu2O octahedral core perfectly. As anode of lithium ion batteries, the core–shell Cu2O/C composite exhibits high and stable columbic efficiency (98%) as well as a reversible capacity of 400 mAh g−1 after 80 cycles. The improved electrochemical performance is attributed to the novel core–shell structure, in which the carbon shell reduces the electrode polarization and promotes the charge transfer at active material/electrolyte interface, and also acts as a stabilizer to keep the octahedral structure integrity during discharge–charge processes

  18. Long Wavelength Plasmonic Absorption Enhancement in Silicon Using Optical Lithography Compatible Core-Shell-Type Nanowires

    Mohammed Shahriar Sabuktagin

    2014-01-01

    Full Text Available Plasmonic properties of rectangular core-shell type nanowires embedded in thin film silicon solar cell structure were characterized using FDTD simulations. Plasmon resonance of these nanowires showed tunability from  nm. However this absorption was significantly smaller than the Ohmic loss in the silver shell due to very low near-bandgap absorption properties of silicon. Prospect of improving enhanced absorption in silicon to Ohmic loss ratio by utilizing dual capability of these nanowires in boosting impurity photovoltaic effect and efficient extraction of the photogenerated carriers was discussed. Our results indicate that high volume fabrication capacity of optical lithography techniques can be utilized for plasmonic absorption enhancement in thin film silicon solar cells over the entire long wavelength range of solar radiation.

  19. Silver-nickel oxide core-shell nanoparticle array electrode with enhanced lithium-storage performance

    We demonstrate the synthesis of Ag-NiO core-shell nanoparticle arrays via a one-step solution-immersion process and subsequent RF-sputtering technique. The Ag nanoparticle arrays on copper substrate are firstly prepared by a displacement reaction at mild temperature of 303K. Then, a NiO layer is deposited onto the surface of the Ag nanoparticles via RF-sputtering technique. When evaluated as an anode for lithium-ion batteries, the Ag-NiO core-shell electrode shows higher capacity and better cycling performance than the planar NiO electrode. The in-situ synthesized Ag nanoparticles can enhance the interfacial strength between the active material and substrate, andimprove the electrical conductivity of the electrode, which may be responsible for the enhanced performance

  20. Significant Broadband Photocurrent Enhancement by Au-CZTS Core-Shell Nanostructured Photocathodes

    Xuemei Zhang; Xu Wu; Anthony Centeno; Ryan, Mary P.; Alford, Neil M.; D. Jason Riley; Fang Xie

    2016-01-01

    Copper zinc tin sulfide (CZTS) is a promising material for harvesting solar energy due to its abundance and non-toxicity. However, its poor performance hinders their wide application. In this paper gold (Au) nanoparticles are successfully incorporated into CZTS to form Au@CZTS core-shell nanostructures. The photocathode of Au@CZTS nanostructures exhibits enhanced optical absorption characteristics and improved incident photon-to-current efficiency (IPCE) performance. It is demonstrated that u...

  1. Hydrothermal synthesis of core-shell TiO2 to enhance the photocatalytic hydrogen evolution

    Jiang, Jinghui; Zhou, Han; Zhang, Fan; Fan, Tongxiang; Zhang, Di

    2016-04-01

    A hydrothermal approach was designed to synthesize core-shell TiO2 with interior cavity by making sodium dodecyl sulfonate (SDS) as the surfactant and the mixture of water and ethanol as the solvent. The control experiment of solvent reveals ethanol and water are responsible for the formation of sphere and interior cavity, respectively. Besides, SDS can assist the growth of core-shell structure, and the sizes of sphere and interior cavity can be tuned by regulating the reaction time or temperature. UV-vis absorption proves core-shell structure with interior cavity can increase the absorption of incident light to enhance the optical activity of final product. The calculated bandgap and photoluminescence (PL) analyses reveal the coexistence of rutile in final product can optimize the bandgap to 3.03 eV and delay the charge recombination. As a result, an effective photocatalytic hydrogen evolution under full spectrum irradiation can be harvested by the as-synthesized core-shell spheres to reach a quantum yield, approximately 9.57% at 340 nm wavelength.

  2. Distribution and compartmental organization of GABAergic medium-sized spiny neurons in the mouse nucleus accumbens.

    Gangarossa, Giuseppe; Espallergues, Julie; de Kerchove d'Exaerde, Alban; El Mestikawy, Salah; Gerfen, Charles R; Hervé, Denis; Girault, Jean-Antoine; Valjent, Emmanuel

    2013-01-01

    The nucleus accumbens (NAc) is a critical brain region involved in many reward-related behaviors. The NAc comprises major compartments the core and the shell, which encompass several subterritories. GABAergic medium-sized spiny neurons (MSNs) constitute the output neurons of the NAc core and shell. While the functional organization of the NAc core outputs resembles the one described for the dorsal striatum, a simple classification of the NAc shell neurons has been difficult to define due to the complexity of the compartmental segregation of cells. We used a variety of BAC transgenic mice expressing enhanced green fluorescence (EGFP) or the Cre-recombinase (Cre) under the control of the promoter of dopamine D1, D2, and D3 receptors and of adenosine A2a receptor to dissect the microanatomy of the NAc. Moreover, using various immunological markers we characterized in detail the distribution of MSNs in the mouse NAc. In addition, cell-type specific extracellular signal-regulated kinase (ERK) phosphorylation in the NAc subterritories was analyzed following acute administration of SKF81297 (a D1R-like agonist), quinpirole (a D2 receptors (D2R)-like agonist), apomorphine (a non-selective DA receptor agonist), raclopride (a D2R-like antagonist), and psychostimulant drugs, including cocaine and d-amphetamine. Each drug generated a unique topography and cell-type specific activation of ERK in the NAc. Our results show the existence of marked differences in the receptor expression pattern and functional activation of MSNs within the shell subterritories. This study emphasizes the anatomical and functional heterogeneity of the NAc, which will have to be considered in its further study. PMID:23423476

  3. Distribution and compartmental organization of GABAergic medium-sized spiny neurons in the mouse Nucleus Accumbens

    Giuseppe eGangarossa

    2013-02-01

    Full Text Available The nucleus accumbens (NAc is a critical brain region involved in many reward-related behaviors. The NAc comprises major compartments the core and the shell, which encompass several subterritories. GABAergic medium-sized spiny neurons (MSNs constitute the output neurons of the NAc core and shell. While the functional organization of the NAc core outputs resembles the one described for the dorsal striatum, a simple classification of the NAc shell neurons has been difficult to define due to the complexity of the compartmental segregation of cells. We used a variety of BAC transgenic mice expressing enhanced green fluorescence (EGFP or the Cre-recombinase (Cre under the control of the promoter of dopamine D1, D2, and D3 receptors and of adenosine A2a receptor to dissect the microanatomy of the NAc. Moreover, using various immunological markers we characterized in detail the distribution of MSNs in the mouse NAc. In addition, cell-type specific ERK phosphorylation in the NAc subterritories was analyzed following acute administration of SKF81297 (a D1R-like agonist, quinpirole (a D2R-like agonist, apomorphine (a non-selective DA receptor agonist, raclopride (a D2R-like antagonist, and psychostimulant drugs, including cocaine and d-amphetamine. Each drug generated a unique topography and cell-type specific activation of ERK in the NAc. Our results show the existence of marked differences in the receptor expression pattern and functional activation of MSNs within the shell subterritories. This study emphasizes the anatomical and functional heterogeneity of the NAc, which will have to be considered in its further study.

  4. Glucocorticoids interact with the noradrenergic arousal system in the nucleus accumbens shell to enhance memory consolidation of both appetitive and aversive taste learning

    Wichmann, Romy; Fornari, Raquel V.; Roozendaal, Benno

    2012-01-01

    It is well established that glucocorticoid hormones strengthen the consolidation of long-term memory of emotionally arousing experiences but have little effect on memory of low-arousing experiences. Although both positive and negative emotionally arousing events tend to be well remembered, studies i

  5. Enhancement and prediction of modulus of elasticity of palm kernel shell concrete

    Research highlights: → Micro-pores of size 16-24 μm were found on the outer surface of palm kernel shell. → Infilling of pores by mineral admixtures was evident. → Sand content influenced both modulus of elasticity and compressive strength. → Proposed equation predicts modulus of elasticity within ±1.5 kN/mm2 of test results. -- Abstract: This paper presents results of an investigation conducted to enhance and predict the modulus of elasticity (MOE) of palm kernel shell concrete (PKSC). Scanning electron microscopic (SEM) analysis on palm kernel shell (PKS) was conducted. Further, the effect of varying sand and PKS contents and mineral admixtures (silica fume and fly ash) on compressive strength and MOE was investigated. The variables include water-to-binder (w/b) and sand-to-cement (s/c) ratios. Nine concrete mixes were prepared, and tests on static and dynamic moduli of elasticity and compressive strength were conducted. The SEM result showed presence of large number of micro-pores on PKS. The mineral admixtures uniformly filled the micro-pores on the outer surface of PKS. Further, the increase in sand content coupled with reduction in PKS content enhanced the compressive strength and static MOE: The highest MOE recorded in this investigation, 11 kN/mm2, was twice that previously published. Moreover, the proposed equation based on CEB/FIP code formula appears to predict the MOE close to the experimental values.

  6. Facile synthesis of CdS@TiO2 core–shell nanorods with controllable shell thickness and enhanced photocatalytic activity under visible light irradiation

    Graphical abstract: - Highlights: • CdS nanorods were coated with amorphous TiO2 shells under a mild condition. • The TiO2 shell thickness can be controlled from 3.5 to 40 nm. • CdS@TiO2 nanorods exhibit enhanced photocatalytic activities under visible light. • Efficient charge carriers separation leads to the improved photocatalytic activity. - Abstract: Amorphous TiO2 layers with a controllable thickness from 3.5 to 40 nm were coated on the one-dimensional CdS nanorods surface under mild conditions. Compared to the bare CdS nanorods, the as-prepared CdS@TiO2 nanorods exhibit enhanced photocatalytic activities for phenol photodecomposition under visible light irradiation. The improved photoactivity is ascribed to the efficient separation of photogenerated electron and hole charge carriers between CdS cores and TiO2 shells. This study promises a simple approach to fabricating CdS@TiO2 core–shell structure nanocomposites, and can be applied for other semiconductor cores with TiO2 shells

  7. Facile synthesis of CdS@TiO{sub 2} core–shell nanorods with controllable shell thickness and enhanced photocatalytic activity under visible light irradiation

    Dong, Wenhao [Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543 (Singapore); Singapore-Peking University Research Centre, Centre for Research Excellence & Technological Enterprise (CREATE), Singapore 138602 (Singapore); Pan, Feng, E-mail: chmpf@nus.edu.sg [Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543 (Singapore); Singapore-Peking University Research Centre, Centre for Research Excellence & Technological Enterprise (CREATE), Singapore 138602 (Singapore); Xu, Leilei [Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543 (Singapore); Singapore-Peking University Research Centre, Centre for Research Excellence & Technological Enterprise (CREATE), Singapore 138602 (Singapore); Zheng, Minrui; Sow, Chorng Haur [Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551 (Singapore); Wu, Kai [Singapore-Peking University Research Centre, Centre for Research Excellence & Technological Enterprise (CREATE), Singapore 138602 (Singapore); BNLMS, SKLSCUSS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Xu, Guo Qin [Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543 (Singapore); Singapore-Peking University Research Centre, Centre for Research Excellence & Technological Enterprise (CREATE), Singapore 138602 (Singapore); National University of Singapore (Suzhou) Research Institute, 377 Lin Quan Street, Suzhou Industrial Park, Jiangsu Prov. 215123 (China); and others

    2015-09-15

    Graphical abstract: - Highlights: • CdS nanorods were coated with amorphous TiO{sub 2} shells under a mild condition. • The TiO{sub 2} shell thickness can be controlled from 3.5 to 40 nm. • CdS@TiO{sub 2} nanorods exhibit enhanced photocatalytic activities under visible light. • Efficient charge carriers separation leads to the improved photocatalytic activity. - Abstract: Amorphous TiO{sub 2} layers with a controllable thickness from 3.5 to 40 nm were coated on the one-dimensional CdS nanorods surface under mild conditions. Compared to the bare CdS nanorods, the as-prepared CdS@TiO{sub 2} nanorods exhibit enhanced photocatalytic activities for phenol photodecomposition under visible light irradiation. The improved photoactivity is ascribed to the efficient separation of photogenerated electron and hole charge carriers between CdS cores and TiO{sub 2} shells. This study promises a simple approach to fabricating CdS@TiO{sub 2} core–shell structure nanocomposites, and can be applied for other semiconductor cores with TiO{sub 2} shells.

  8. Significant Broadband Photocurrent Enhancement by Au-CZTS Core-Shell Nanostructured Photocathodes

    Zhang, Xuemei; Wu, Xu; Centeno, Anthony; Ryan, Mary P.; Alford, Neil M.; Riley, D. Jason; Xie, Fang

    2016-03-01

    Copper zinc tin sulfide (CZTS) is a promising material for harvesting solar energy due to its abundance and non-toxicity. However, its poor performance hinders their wide application. In this paper gold (Au) nanoparticles are successfully incorporated into CZTS to form Au@CZTS core-shell nanostructures. The photocathode of Au@CZTS nanostructures exhibits enhanced optical absorption characteristics and improved incident photon-to-current efficiency (IPCE) performance. It is demonstrated that using this photocathode there is a significant increase of the power conversion efficiency (PCE) of a photoelectrochemical solar cell of 100% compared to using a CZTS without Au core. More importantly, the PCE of Au@CZTS photocathode improved by 15.8% compared to standard platinum (Pt) counter electrode. The increased efficiency is attributed to plasmon resonance energy transfer (PRET) between the Au nanoparticle core and the CZTS shell at wavelengths shorter than the localized surface plasmon resonance (LSPR) peak of the Au and the semiconductor bandgap.

  9. Core/shell nanoparticles for multiple biological detection with enhanced sensitivity and kinetics

    The paper shows the different methods to attach a molecule to detect streptavidin to a dielectric particle made of a rare-earth oxide core and a polysiloxane shell containing fluorescein. First, the detection of streptavidin binding on a biotinylated gold substrate can be achieved in three ways: the shift of the surface plasmon resonance of the substrate and the double luminescence (organic and inorganic) of the core/shell particle. Second, these detections are efficient even after elimination upon thermal annealing of all the undesired molecules that skew the assays. Finally, the particle that ballasts the protein enhances its binding kinetics and increases the localized surface plasmon resonance shift that detects the binding.

  10. Progress of the Enhanced Hanford Single Shell Tank (SST) Integrity Project

    Venetz, Theodore J. [Washington River Protection Solutions, Richland, WA (United States); Washenfelder, Dennis J. [Washington River Protection Solutions, Richland, WA (United States); Boomer, Kayle D. [Washington River Protection Solutions, Richland, WA (United States); Johnson, Jeremy M. [USDOE Office of River Protection, Richland, WA (United States); Castleberry, Jim L. [Washington River Protection Solutions, Richland, WA (United States)

    2015-01-07

    To improve the understanding of the single-shell tanks (SSTs) integrity, Washington River Protection Solutions, LLC (WRPS), the USDOE Hanford Site tank contractor, developed an enhanced Single-Shell Tank Integrity Project (SSTIP) in 2009. An expert panel on SST integrity, consisting of various subject matters experts in industry and academia, was created to provide recommendations supporting the development of the project. This panel developed 33 recommendations in four main areas of interest: structural integrity, liner degradation, leak integrity and prevention, and mitigation of contamination migration. In late 2010, seventeen of these recommendations were used to develop the basis for the M-45-10-1 Change Package for the Hanford Federal Agreement and Compliance Order, which is also known as the Tri-Party Agreement.

  11. Progress of the Enhanced Hanford Single Shell Tank (SST) Integrity Project

    To improve the understanding of the single-shell tanks (SSTs) integrity, Washington River Protection Solutions, LLC (WRPS), the USDOE Hanford Site tank contractor, developed an enhanced Single-Shell Tank Integrity Project (SSTIP) in 2009. An expert panel on SST integrity, consisting of various subject matters experts in industry and academia, was created to provide recommendations supporting the development of the project. This panel developed 33 recommendations in four main areas of interest: structural integrity, liner degradation, leak integrity and prevention, and mitigation of contamination migration. In late 2010, seventeen of these recommendations were used to develop the basis for the M-45-10-1 Change Package for the Hanford Federal Agreement and Compliance Order, which is also known as the Tri-Party Agreement.

  12. Hybrid Ag@TiO2 core–shell nanostructures with highly enhanced photocatalytic performance

    A new synthetic approach has been developed to prepare silver@titanium dioxide (Ag@TiO2) core–shell nanostructures with controllable size, shape, crystal phase and function at ambient conditions (e.g. in water, ≤100 ° C). This approach shows a few unique features, including short reaction time (a few minutes) for forming core–shell nanostructures, no requirement of high temperature calcinations for generating TiO2 (e.g. at ∼100 ° C in our case), tunable TiO2 shell thickness, high yield and good reproducibility. The experimental results show that the Ag@TiO2 core–shell nanostructures exhibit excellent photocatalytic activity compared to the commercial TiO2 (P25) and Ag-doped TiO2 nanocomposite in the degradation of organic dye molecules (e.g. methyl orange) with ultraviolet (UV) irradiation. This could be attributed to the large surface area of TiO2 nanoparticles for maximum harvesting of UV light, mixed anatase and rutile crystalline phases in the TiO2 shell and the effective charge separation between Ag and TiO2 that can reduce the possible recombination of electron–hole (e−–h+) pairs within TiO2 generated under UV radiation. To further understand the charge separation situation within Ag–TiO2 composites, theoretical simulation (e.g. density functional theory, DFT) was employed in this study. The DFT simulation results indicate that for the Ag@TiO2 core–shell nanostructures, photo-generated electrons transfer readily from the external TiO2 layer to the internal Ag layer with heavy accumulation compared to those doping Ag on TiO2 surfaces, which may reduce the recombination of e−–h+ pairs and thus enhance the photocatalytic efficiency. The findings may open a new strategy to synthesize TiO2-based photocatalysts with highly enhanced efficiency for environmental remediation applications. (paper)

  13. Hybrid Ag@TiO2 core-shell nanostructures with highly enhanced photocatalytic performance

    Yang, X. H.; Fu, H. T.; Wong, K.; Jiang, X. C.; Yu, A. B.

    2013-10-01

    A new synthetic approach has been developed to prepare silver@titanium dioxide (Ag@TiO2) core-shell nanostructures with controllable size, shape, crystal phase and function at ambient conditions (e.g. in water, ≤100 ° C). This approach shows a few unique features, including short reaction time (a few minutes) for forming core-shell nanostructures, no requirement of high temperature calcinations for generating TiO2 (e.g. at ˜100 ° C in our case), tunable TiO2 shell thickness, high yield and good reproducibility. The experimental results show that the Ag@TiO2 core-shell nanostructures exhibit excellent photocatalytic activity compared to the commercial TiO2 (P25) and Ag-doped TiO2 nanocomposite in the degradation of organic dye molecules (e.g. methyl orange) with ultraviolet (UV) irradiation. This could be attributed to the large surface area of TiO2 nanoparticles for maximum harvesting of UV light, mixed anatase and rutile crystalline phases in the TiO2 shell and the effective charge separation between Ag and TiO2 that can reduce the possible recombination of electron-hole (e--h+) pairs within TiO2 generated under UV radiation. To further understand the charge separation situation within Ag-TiO2 composites, theoretical simulation (e.g. density functional theory, DFT) was employed in this study. The DFT simulation results indicate that for the Ag@TiO2 core-shell nanostructures, photo-generated electrons transfer readily from the external TiO2 layer to the internal Ag layer with heavy accumulation compared to those doping Ag on TiO2 surfaces, which may reduce the recombination of e--h+ pairs and thus enhance the photocatalytic efficiency. The findings may open a new strategy to synthesize TiO2-based photocatalysts with highly enhanced efficiency for environmental remediation applications.

  14. Iptkalim inhibits cocaine challenge—induced enhancement of dopamine levels in nucleus accumbens and striatum of rats by up—regulating Kir6.1 and Kir6.2 mRNA expression

    HEHai-Rong; DINGJian-Hua; GUBing; WANGHai; HUGang; LIUYun

    2003-01-01

    AIM:To investigate the effect and mechanism of novel ATP-sensitive potassium channel opener (KCO) iptkalim (IPT) on acute and cocaine challenge-induced alterations in the levels of dopamine (DA) and glutamate (Glu) from nucleus accumbens (NAc), striatum, and prefrontal cortex (PFC) in rats. METHODS: The levels of DA and Glu were assayed using high performance liquid chromatography (HPLC) combined with amperometric and fluorescent detection, respectively. The mRNA levels of Kir6.1, Kir6.2, SUR1, and SUR2 were measured by semiquantitative reverse transcription polymerase chain reaction (RT-PCR). RESULTS: IPT did not affect acute cocaine (30mg/kg,ip)-induced elevations in either DA levels from NAc and striatum or Glu levels from NAc and PFC. An acute cocaine challenge (30mg/kg,ip) on d 21 after withdrawal caused an elevation in DA levels in NAc and striatum. Moreover, the same treatment also increased Gluo levels in PFC and NAc of cocaine-pretreated rats. Repeated IPT injections reversed cocaine challenge-induced DA increase in NAc and striatum. Cocaine challenge increased Kir6.1 and Kir6.2 mRNA expression in striatum and NAc and only elevate Kir6.2 expression in PFC in both cocainepretreated rats and rats pretreated with IPT plus cocaine. Moreover, expression of Kir6.1 and Kir6.2 mRNA was augmented in rats pretreated with IPT plus cocaine compared to rats pretreated with cocaine alone. No significant change was found in the SUR1 and SUR2 expression of all four groups. CONCLUSION:IPT inhibited cocaine challenge-induced enhancement of DA levels in NAc and striatum by up-regulating Kir6.1 and Kir6.2 mRNA expression.

  15. Preparation and enhanced photocatalytic activity of CdS@RGO core–shell structural microspheres

    Liu, Hui, E-mail: liuhui@sust.edu.cn; Lv, Ting; Wu, Xiaohua; Zhu, Chunkui; Zhu, Zhenfeng

    2014-06-01

    Reduced graphene oxide (RGO) wrapped CdS microspheres with enhanced photocatalytic activity were successfully synthesized via a two-step hydrothermal method. The as-prepared samples were carefully characterized by X-ray diffraction, scanning electron microscopy and Raman spectrometer. The photocatalytic activity of the as-prepared samples was evaluated by photocatalytic decolorization of Rhodamine B (RhB) under visible light irradiation. Due to its large surface area and stepwise structure of energy level, which result in the efficiently enhancing of the adsorption performance of dye molecules and suppressing of the charge recombination of photocatalytst, a remarkably enhanced degradation rate of RhB dye about 95.2% within 50 min has been observed. In addition, the introduction of the graphene shell could effectively protect the internal CdS microsheres from photocorrosion, and the composite showed an excellent recyclability property for its photocatalytic applications.

  16. Pure surface plasmon resonance enhancement of the first hyperpolarizability of gold core-silver shell nanoparticles.

    Abid, Jean-Pierre; Nappa, Jérôme; Girault, Hubert H; Brevet, Pierre-François

    2004-12-22

    We report the optical second harmonic (SH) response from gold core-silver shell nanoparticles supported at a liquid-liquid interface in the spectral region where the second harmonic generation (SHG) frequency is resonant with the surface plasmon (SP) resonance excitation of the nanoparticles. We compare these results with that obtained by classical linear optical absorption spectroscopy and show that the nonlinear optical response is dominated by the SP resonance enhancement with negligible contributions from the interband transitions. As a result, the SH spectrum exhibits two clear SP resonance bands attributed to the two SP resonances of the composite nanostructure formed by the gold core-silver shell nanoparticles. Absolute values of the hyperpolarizabilities are measured by hyper Rayleigh scattering (HRS) and compared that of pure gold nanoparticles. The hyperpolarizability measured at a harmonic energy of 3.0 eV, enhanced through excitation of the high energy SP resonance of the nanoparticle, increases with the silver content whereas the hyperpolarizability measured at a harmonic energy of 2.4 eV, enhanced through the excitation of the low energy SP resonance of the nanoparticle, decreases because of the shift of this resonance away from the harmonic frequency. The hyperpolarizability determined by HRS and the square root of the SHG intensities, scaling with the nanoparticle hyperpolarizability, have similar trends with respect to the silver content indicative of closely related adsorption properties yielding similar surface concentrations at the liquid-liquid interface. PMID:15606279

  17. Enhanced optical responses of Au@Pd core/shell nanobars.

    Zhang, Ke; Xiang, Yanjuan; Wu, Xiaochun; Feng, Lili; He, Weiwei; Liu, Jianbo; Zhou, Weiya; Xie, Sishen

    2009-01-20

    A Pd nanoshell was epitaxially grown on a Au nanorod (NR) via simple seed-mediated growth. Compared with the cylindrical shape of the Au NR, the Au core/Pd shell (Au@Pd) nanorods change to a rectangular shape due to the disappearance of {110} facets. The Au NRs exhibit a strong longitudinal surface plasmon resonance (LSPR). As Pd is deposited, damping and broadening occur to the LSPR band. Interestingly, the LSPR band maximum first shows a small red-shift (ca. 40 nm) which then is followed by a blue-shift as the amount of Pd is increased. A thickness-dependent LSPR feature of the Pd shell is believed to contribute to the shift. At a thinner Pd thickness, the Au@Pd nanobars exhibit a well-defined LSPR band in the visible and near-infrared region, which demonstrates a higher dielectric sensitivity than that of the corresponding Au NRs. It thus opens up the potential of Pd nanostructures for SPR-based sensing. Investigations on the surface-enhanced Raman scattering (SERS) indicate that the SERS activities of the Au@Pd nanobars at thicknesses smaller than 2.5 nm mainly originate from the Au cores; thus, the SERS activities can be improved by tuning the aspect ratio of the Au core and/or the Pd shell thickness. PMID:19090666

  18. Shell evolution in neutron-rich carbon isotopes: Unexpected enhanced role of neutron–neutron correlation

    Full shell-model diagonalization has been performed to study the structure of neutron-rich nuclei around 20C. We investigate in detail the roles played by the different monopole components of the effective interaction in the evolution of the N=14 shell in C, N and O isotopes. It is found that the relevant neutron–neutron monopole terms, Vd5/2d5/2nn and Vs1/2s1/2nn, contribute significantly to the reduction of the N=14 shell gap in C and N isotopes in comparison with that in O isotopes. The origin of this unexpectedly large effect, which is comparable with (sometimes even larger than) that caused by the proton–neutron interaction, is related to the enhanced configuration mixing in those nuclei due to many-body correlations. Such a scheme is also supported by the large B(E2) value in the nucleus 20C which has been measured recently.

  19. Melting of Nanoprticle-Enhanced Phase Change Material inside Shell and Tube Heat Exchanger

    Seiyed Mohammad Javad Hosseini

    2013-01-01

    Full Text Available This paper presents a numerical study of melting of Nanoprticle-Enhanced phase change material (NEPCM inside a shell and tube heat exchanger using RT50 and copper particles as base material and nanoparticle, respectively. In this study, the effects of nanoparticles dispersion (, 0.03, and 0.05 on melting time, liquid fraction, and penetration length are investigated. The results show that the melting time decreases to 14.6% and the penetration length increases to 146% with increasing volume fraction of nanoparticle up to .

  20. Enhanced Faraday rotation by crystals of core-shell magnetoplasmonic nanoparticles

    Varytis, P.; Pantazopoulos, P. A.; Stefanou, N.

    2016-06-01

    Collective hybridized plasmon modes, which enable strong magnetooptical coupling and consequent enhanced Faraday effect in three-dimensional periodic assemblies of magnetic dielectric nanoparticles coated with a noble-metal shell, are studied by means of rigorous full electrodynamic calculations using an extension of the layer-multiple-scattering method, in conjunction with the effective-medium approximation. A thorough analysis of relevant photonic dispersion diagrams and transmission spectra provides a consistent explanation of the underlying physical mechanisms to a degree that goes beyond existing interpretation. It is shown that properly designed structures of such composite magnetoplasmonic nanoparticles offer a versatile platform for engineering increased and broadband Faraday rotation.

  1. Facile synthesis and enhanced luminescent properties of ZnO/HfO2 core-shell nanowires.

    Zhang, Yuan; Lu, Hong-Liang; Wang, Tao; Ren, Qing-Hua; Gu, Yu-Zhu; Li, De-Hui; Zhang, David Wei

    2015-10-01

    The morphological, structural and photoluminescence properties of one-dimensional ZnO/HfO2 core-shell nanowires (NWs) with various thicknesses of HfO2 shell layers are studied in detail in this work. The ZnO NWs have been fabricated by a simple hydrothermal method, which are then coated by thin HfO2 shell layers using atomic layer deposition (ALD). The morphological and structural characterization demonstrates that the HfO2 shells with polycrystalline structures grow on the single-crystalline ZnO NWs conformally. Moreover, the ZnO/HfO2 core/shell NWs show remarkable enhanced ultraviolet (UV) emission with increasing thickness of the HfO2 shell layer compared with bare ZnO NWs. The UV emission intensity for the sample with HfO2 shell thickness of ∼16 nm is about 9 times higher than that of bare ZnO NWs. It mainly results from the decreased surface states by surface passivation of the HfO2 shell layer as well as a typical type-I band alignment in the ZnO/HfO2 core/shell structure. A model is also proposed to explain the evolution of the wide visible emission band with the relatively low intensity of the core/shell structures. Our results suggest that the ZnO/HfO2 core/shell structures have potential applications for high-efficiency optoelectronic devices such as UV light-emitting diodes and lasers. PMID:26339774

  2. Nucleus accumbens stimulation in pathological obesity.

    Harat, Marek; Rudaś, Marcin; Zieliński, Piotr; Birska, Julita; Sokal, Paweł

    2016-01-01

    One of the potential treatment methods of obesity is deep brain stimulation (DBS) of nucleus accumbens. We describe the case of 19 years old woman with hypothalamic obesity. She weighted 151.4 kg before DBS and the non-surgical methods proved to be inefficient. She was treated with implantation of DBS electrode to nucleus accumbens bilaterally. Results were measured with body mass index and neuropsychological tests. Follow-up was 14 months. Fourteen months after surgery weight was 138 kg, BMI was 48.3. Neuropsychological test results were intact. The presented case supports the thesis of treatment of obesity with nucleus accumbens stimulation. PMID:27154450

  3. Yolk-shell ZnO-C microspheres with enhanced electrochemical performance as anode material for lithium ion batteries

    Graphical abstract: - Highlights: • ZnO-C yolk-shell microspheres, hollow microspheres and solid microspheres are prepared. • Yolk-shell ZnO-C microspheres possess the best electrochemical properties when used as the anode materials for lithium-ion batteries. • The special yolk-shell structures and extra carbon support account for the enhanced electrochemical properties. - Abstract: Three ZnO-C samples with distinct structures including yolk-shell microspheres, hollow microspheres and solid microspheres are fabricated through a facile chemical solution reaction followed by calcination in argon. When employed as the anode materials for lithium ion batteries, yolk-shell ZnO-C microspheres exhibit the best electrochemical properties than the hollow and solid microspheres. After 150 cycles, yolk-shell ZnO-C microspheres demonstrate a relative high capacity of 520 mA h g−1 at a current density of 100 mA g−1 with a Coulombic efficiency of about 99.3%. The excellent cycling stability and good rate capability of yolk-shell ZnO-C microspheres stem from the synergistic effect of the unique yolk-shell structures and extra carbon support

  4. Large enhanced dielectric permittivity in polyaniline passivated core-shell nano magnetic iron oxide by plasma polymerization

    Commercial samples of Magnetite with size ranging from 25–30 nm were coated with polyaniline by using radio frequency plasma polymerization to achieve a core shell structure of magnetic nanoparticle (core)–Polyaniline (shell). High resolution transmission electron microscopy images confirm the core shell architecture of polyaniline coated iron oxide. The dielectric properties of the material were studied before and after plasma treatment. The polymer coated magnetite particles exhibited a large dielectric permittivity with respect to uncoated samples. The dielectric behavior was modeled using a Maxwell–Wagner capacitor model. A plausible mechanism for the enhancement of dielectric permittivity is proposed

  5. Enhancement of single particle rare earth doped NaYF4: Yb, Er emission with a gold shell

    Upconversion of infrared light to visible light has important implications for bioimaging. However, the small absorption cross-section of rare earth dopants has limited the efficiency of these anti-Stokes nanomaterials. We present enhanced excitation absorption and single particle fluorescent emission of sodium yttrium fluoride, NaYF4: Yb, Er based upconverting nanoparticles coated with a gold nanoshell through surface plasmon resonance. The single gold-shell coated nanoparticles show enhanced absorption in the near infrared, enhanced total emission intensity, and increased green relative to red emission. We also show differences in enhancement between single and aggregated gold shell nanoparticles. The surface plasmon resonance of the gold-shell coated nanoparticle is shown to be dependent on the shell thickness. In contrast to other reported results, our single particle experimental observations are corroborated by finite element calculations that show where the green/red emission enhancement occurs, and what portion of the enhancement is due to electromagnetic effects. We find that the excitation enhancement and green/red emission ratio enhancement occurs at the corners and edges of the doped emissive core. (paper)

  6. Hybrid silica-gold core-shell nanoparticles for fluorescence enhancement

    Grzelak, J.; Krajewska, A.; Krajnik, B.; Jamiola, D.; Choma, J.; Jankiewicz, B.; Piątkowski, D.; Nyga, P.; Mackowski, S.

    2016-06-01

    We demonstrate that SiO2 nanoparticles coated with a gold island film (GIF) provide an efficient plasmonic platform for enhancing fluorescence intensity of chlorophyll-containing photosynthetic complexes. Fluorescence images obtained for single SiO2-Au coreshell nanoparticles mixed with photosynthetic complexes reveal very uniform emission patterns of a circular shape, similarly as observed for bare SiO2 nanoparticles. The fluorescence enhancement of chlorophyll emission for SiO2-Au nanostructures is up to four-fold compared to bare SiO2 nanoparticles and shortening of fluorescence decay indicates its plasmonic origin. For doublets or triplets of core-shell SiO2-Au nanoparticles, the intensity of emission is further increased as a result of hot-spot formation at the interfaces of such assemblies.

  7. Plasmonic luminescent core-shell nanocomposites-enhanced chemiluminescence arising from the decomposition of peroxomonosulfite

    Chen, Hui; Xue, Wei; Lu, Chao; Li, Hai-fang; Zheng, Yongzan; Lin, Jin-Ming

    2013-12-01

    A core-shell structure of plasmonic luminescent nanocomposite, Ni@SiO2@FITC@SiO2 (NSFS) combining the stable luminescence of fluorophore with the excellent plasmonic property of metal nanomaterials, has been synthesized through layer-by-layer assembly. The effect of NSFS on the ultraweak chemiluminescence (CL) reaction of hydrogen peroxide (H2O2) and sodium bisulfite (NaHSO3) was explored for the first time. It was found that the CL intensity from the decomposition of peroxomonosulfite was significantly enhanced by NSFS. The mechanism of the nanocomposite-enhanced CL was revealed as the coupling of chemically induced excited states of fluorescein isothiocyanate (FITC) with surface plasmons of Ni nanoparticles based on studies of CL emission spectra, electron spin resonance spectra, extinction spectra and fluorescence spectra. The work sheds new light on the characteristics of the versatile materials and gives us new insight into the optical properties of fluorophores.

  8. Core-shell nanoparticle-based peptide therapeutics and combined hyperthermia for enhanced cancer cell apoptosis.

    Shah, Birju P; Pasquale, Nicholas; De, Gejing; Tan, Tao; Ma, Jianjie; Lee, Ki-Bum

    2014-09-23

    Mitochondria-targeting peptides have garnered immense interest as potential chemotherapeutics in recent years. However, there is a clear need to develop strategies to overcome the critical limitations of peptides, such as poor solubility and the lack of target specificity, which impede their clinical applications. To this end, we report magnetic core-shell nanoparticle (MCNP)-mediated delivery of a mitochondria-targeting pro-apoptotic amphipathic tail-anchoring peptide (ATAP) to malignant brain and metastatic breast cancer cells. Conjugation of ATAP to the MCNPs significantly enhanced the chemotherapeutic efficacy of ATAP, while the presence of targeting ligands afforded selective delivery to cancer cells. Induction of MCNP-mediated hyperthermia further potentiated the efficacy of ATAP. In summary, a combination of MCNP-mediated ATAP delivery and subsequent hyperthermia resulted in an enhanced effect on mitochondrial dysfunction, thus resulting in increased cancer cell apoptosis. PMID:25133971

  9. Enhancement of shell side forced convective heat transfer on the shell-tube type heat exchanger using thin plate-type supports

    The shell side heat transfer and pressure drop to water flowing counter were experimentally investigated on the basis of the overall heat transfer coefficient. The investigation was intended to identify ways to get higher performance for the cooler in a BWR nuclear power plant. The following three conclusions were reached in the study. (1) From estimated performance of the heat exchanger using the overall heat transfer coefficient based on the outside area of the tube K0, performance of this heat exchanger was enhanced 92% as compared with the measured performance of the conventional segmental heat exchanger. Assuming that the fouling factor is Rf = 8.6 x 10-2 m2K/kW, the former was enhanced about 23%. (2) The tube side pressure drop ΔPt = 20 kPa and the shell side pressure drop ΔPs = 70 kPa were obtained, and they were within the allowable value ΔPa = 80 kPa. The shell side pressure drop of the standard spacer could be decreased 20% as compared with that of the low pressure drop spacer. (3) The enhancement constant of heat transfer of the low pressure drop spacer with thin plate-type supports was about 1.2 times as large as that of the standard spacer. The heat exchanger with the low pressure drop spacer was about 1.6 times more compact than that using the standard spacer. (author)

  10. Nucleus accumbens receives gastric vagal inputs

    Sangeeta MEHENDALE; Jing-tian XIE; Han H AUNG; Xiong-Fei GUAN; Chun-Su YUAN

    2004-01-01

    AIM: To localize and characterize the response of single accumbal neurons to electrical stimulation of the gastric vagal fibers. METHODS: Unitary responses to electrical stimulation of the ventral and dorsal gastric vagal fibers which serve the proximal stomach were recorded extracellularly in the nucleus accumbens in anesthetized cats.RESULTS: The evoked units recorded in the nucleus accumbens consisted of phasic and tonic responses, with a mean latency of (396±43) ms. Convergence of ventral and dorsal gastric vagal inputs onto single phasic and tonic accumbal units was observed. For tonic inhibitory responses, convergence was exhibited when stimulation applied to both the ventral and dorsal gastric vagal branches resulted in a significantly longer inhibitory period than did stimulation of a single gastric vagal branch. Comparing the gastric vagally evoked accumbal unitary responses to the neuronal responses recorded in the nucleus tractus solitarius, parabrachial nucleus and hypothalamus in our previous studies, our data showed a higher percentage of single spike responses and shorter response duration's in the nucleus accumbens than in the other nuclei. This suggests that the synaptic drive from the gastric vagal inputs to the nucleus accumbens is less powerful than in the other structures. CONCLUSION: The present study localized and characterized gastric vagally evoked responses in the nucleus accumbens, which suggest that the nucleus accumbens may process gastric signals concerned with the ingestive process.

  11. The non-peptidic delta opioid receptor agonist TAN-67 enhances dopamine efflux in the nucleus accumbens of freely moving rats via a mechanism that involves both glutamate and free radicals.

    Fusa, K.; Takahashi, I.; Watanabe, S.; Aono, Y.; Ikeda, H.; Saigusa, T.; Nagase, H.; Suzuki, T.; Koshikawa, N.; Cools, A.R.

    2005-01-01

    The activation of the delta-opioid receptors in the nucleus accumbens is known to induce a large and rapid increase of accumbal dopamine efflux. (+/-)-TAN-67 (2-methyl-4a(alpha)-(3-hydroxyphenyl)-1,2,3,4,4a,5,12,12a(alpha)-octahydro -quinolino[2,3,3,-g]isoquinoline) is a centrally acting non-peptidi

  12. Magneto-optical enhancement by surface plasmon resonance in magnetic ``nano-onions'' with multicore-shell structures

    Abe, Masanori; Takeshi, Suwa

    2005-05-01

    Calculations based on the Maxwell-Garnett theory revealed a remarkable enhancement of the magneto-optical effect due to surface plasmon resonance excited in nanometer sized magnetic particles ("nano-onions") with n-fold core-shell structures consisting of shell(s) and/or a core of noble metals such as Au and Ag. The Kerr effect was found to be greatly enhanced in a composite containing nano-onions of threefold Fe (orCoFe2O4)(core)/dielectric(shell)/Ag(shell) structure and also in a composite containing twofold Bi-YIG(core)/Ag(shell) nano-onions. In the latter case, the Kerr rotation angle as large as 13.5° was obtained with a figure of merit, θK√R =62°, (R is the reflectivity) at ℏω =2.6eV, which is much larger than the highest values of θK=19° and θK√R =1.1°, reported for PtMnSb.

  13. Significant Broadband Photocurrent Enhancement by Au-CZTS Core-Shell Nanostructured Photocathodes.

    Zhang, Xuemei; Wu, Xu; Centeno, Anthony; Ryan, Mary P; Alford, Neil M; Riley, D Jason; Xie, Fang

    2016-01-01

    Copper zinc tin sulfide (CZTS) is a promising material for harvesting solar energy due to its abundance and non-toxicity. However, its poor performance hinders their wide application. In this paper gold (Au) nanoparticles are successfully incorporated into CZTS to form Au@CZTS core-shell nanostructures. The photocathode of Au@CZTS nanostructures exhibits enhanced optical absorption characteristics and improved incident photon-to-current efficiency (IPCE) performance. It is demonstrated that using this photocathode there is a significant increase of the power conversion efficiency (PCE) of a photoelectrochemical solar cell of 100% compared to using a CZTS without Au core. More importantly, the PCE of Au@CZTS photocathode improved by 15.8% compared to standard platinum (Pt) counter electrode. The increased efficiency is attributed to plasmon resonance energy transfer (PRET) between the Au nanoparticle core and the CZTS shell at wavelengths shorter than the localized surface plasmon resonance (LSPR) peak of the Au and the semiconductor bandgap. PMID:26997140

  14. (Gold core) at (ceria shell) nanostructures for plasmon-enhanced catalytic reactions under visible light

    Wang, Jianfang

    2014-08-26

    Driving catalytic reactions with sunlight is an excellent example of sustainable chemistry. A prerequisite of solar-driven catalytic reactions is the development of photocatalysts with high solar-harvesting efficiencies and catalytic activities. Herein, we describe a general approach for uniformly coating ceria on monometallic and bimetallic nanocrystals through heterogeneous nucleation and growth. The method allows for control of the shape, size, and type of the metal core as well as the thickness of the ceria shell. The plasmon shifts of the Au@CeO2 nanostructures resulting from the switching between Ce(IV) and Ce(III) are observed. The selective oxidation of benzyl alcohol to benzaldehyde, one of the fundamental reactions for organic synthesis, performed under both broad-band and monochromatic light, demonstrates the visible-light-driven catalytic activity and reveals the synergistic effect on the enhanced catalysis of the Au@CeO2 nanostructures. © 2014 American Chemical Society.

  15. Orientation-induced enhancement in electromagnetic properties of ZnFe2O4/SiO2/PANI core/shell/shell nanostructured disks

    Wang, Jiaheng; Or, Siu Wing

    2016-05-01

    ZnFe2O4/SiO2/PANI (ZSP) core/shell/shell nanostructured disks are prepared and fabricated into paraffin-bonded ZSP composite rings with random, vertical, and horizontal orientations of the easy magnetization planes of the ZSP disks in the paraffin binder in order to study the effect of directional orientation of the easy magnetization planes on their electromagnetic properties. The easy magnetization planes induced by shape anisotropy and oriented by a magnetic field in the vertically oriented ring result in a general enhancement in permeability of 7-60% in the broad UHF-Ku (0.1-18 GHz) bands, while those in the horizontally oriented ring lead to a significant enhancement of 58-1100% in the low-frequency L and S (1-4 GHz) bands, in comparison with the randomly oriented ring. The observed permeability agrees with the theoretical prediction based on the Landau-Lifshitz-Gilbert equation and the Bruggeman's effective medium theory. The horizontal and vertical arrangements of dipolar polarizations in the vertically and horizontally oriented rings give rise to 3-11% enhancement and weakening in permittivity, respectively, compared to the randomly oriented ring. The enhancement in permeability also improves and broadens the electromagnetic wave absorption in both vertically and horizontally oriented rings, especially in the L and S bands for the horizontally oriented ring.

  16. Dopamine and opioid systems interact within the nucleus accumbens to maintain monogamous pair bonds

    Resendez, Shanna L; Keyes, Piper C; Day, Jeremy J; Hambro, Caely; Austin, Curtis J; Maina, Francis K; Eidson, Lori N; Porter-Stransky, Kirsten A; Nevárez, Natalie; McLean, J William; Kuhnmuench, Morgan A; Murphy, Anne Z; Mathews, Tiffany A; Aragona, Brandon J

    2016-01-01

    Prairie vole breeder pairs form monogamous pair bonds, which are maintained through the expression of selective aggression toward novel conspecifics. Here, we utilize behavioral and anatomical techniques to extend the current understanding of neural mechanisms that mediate pair bond maintenance. For both sexes, we show that pair bonding up-regulates mRNA expression for genes encoding D1-like dopamine (DA) receptors and dynorphin as well as enhances stimulated DA release within the nucleus accumbens (NAc). We next show that D1-like receptor regulation of selective aggression is mediated through downstream activation of kappa-opioid receptors (KORs) and that activation of these receptors mediates social avoidance. Finally, we also identified sex-specific alterations in KOR binding density within the NAc shell of paired males and demonstrate that this alteration contributes to the neuroprotective effect of pair bonding against drug reward. Together, these findings suggest motivational and valence processing systems interact to mediate the maintenance of social bonds. DOI: http://dx.doi.org/10.7554/eLife.15325.001 PMID:27371827

  17. Music and the nucleus accumbens.

    Mavridis, Ioannis N

    2015-03-01

    Music is a universal feature of human societies over time, mainly because it allows expression and regulation of strong emotions, thus influencing moods and evoking pleasure. The nucleus accumbens (NA), the most important pleasure center of the human brain (dominates the reward system), is the 'king of neurosciences' and dopamine (DA) can be rightfully considered as its 'crown' due to the fundamental role that this neurotransmitter plays in the brain's reward system. Purpose of this article was to review the existing literature regarding the relation between music and the NA. Studies have shown that reward value for music can be coded by activity levels in the NA, whose functional connectivity with auditory and frontal areas increases as a function of increasing musical reward. Listening to music strongly modulates activity in a network of mesolimbic structures involved in reward processing including the NA. The functional connectivity between brain regions mediating reward, autonomic and cognitive processing provides insight into understanding why listening to music is one of the most rewarding and pleasurable human experiences. Musical stimuli can significantly increase extracellular DA levels in the NA. NA DA and serotonin were found significantly higher in animals exposed to music. Finally, passive listening to unfamiliar although liked music showed activations in the NA. PMID:25102783

  18. The gamma-aminobutyric acid type B (GABAB receptor agonist baclofen inhibits morphine sensitization by decreasing the dopamine level in rat nucleus accumbens

    Fu Zhenyu

    2012-07-01

    Full Text Available Abstract Background Repeated morphine exposure can induce behavioral sensitization. There are evidences have shown that central gamma-aminobutyric acid (GABA system is involved in morphine dependence. However, the effect of a GABAB receptor agonist baclofen on morphine-induced behavioral sensitization in rats is unclear. Methods We used morphine-induced behavioral sensitization model in rat to investigate the effects of baclofen on behavioral sensitization. Moreover, dopamine release in the shell of the nucleus accumbens was evaluated using microdialysis assay in vivo. Results The present study demonstrated that morphine challenge (3 mg/kg, s.c. obviously enhanced the locomotor activity following 4-day consecutive morphine administration and 3-day withdrawal period, which indicated the expression of morphine sensitization. In addition, chronic treatment with baclofen (2.5, 5 mg/kg significantly inhibited the development of morphine sensitization. It was also found that morphine challenge 3 days after repeated morphine administration produced a significant increase of extracellular dopamine release in nucleus accumbens. Furthermore, chronic treatment with baclofen decreased the dopamine release induced by morphine challenge. Conclusions Our results indicated that gamma-aminobutyric acid system plays an important role in the morphine sensitization in rat and suggested that behavioral sensitization is a promising model to study the mechanism underlying drug abuse.

  19. OVERVIEW OF ENHANCED HANFORD SINGLE-SHELL TANK (SST) INTEGRITY PROJECT - 12128

    VENETZ TJ; BOOMER KD; WASHENFELDER DJ; JOHNSON JB

    2012-01-25

    To improve the understanding of the single-shell tanks integrity, Washington River Protection Solutions, LLC, the USDOE Hanford Site tank contractor, developed an enhanced Single-Shell Tank (SST) Integrity Project in 2009. An expert panel on SST integrity, consisting of various subject matters experts in industry and academia, was created to provide recommendations supporting the development of the project. This panel developed 33 recommendations in four main areas of interest: structural integrity, liner degradation, leak integrity and prevention, and mitigation of contamination migration, Seventeen of these recommendations were used to develop the basis for the M-45-10-1 Change Package for the Hanford Federal Agreement and Compliance Order, which is also known as the Tri-Party Agreement. The change package identified two phases of work for SST integrity. The initial phase has been focused on efforts to envelope the integrity of the tanks. The initial phase was divided into two primary areas of investigation: structural integrity and leak integrity. If necessary based on the outcome from the initial work, a second phase would be focused on further definition of the integrity of the concrete and liners. Combined these two phases are designed to support the formal integrity assessment of the Hanford SSTs in 2018 by Independent Qualified Registered Engineer. The work to further define the DOE's understanding of the structural integrity SSTs involves preparing a modern Analysis of Record using a finite element analysis program. Structural analyses of the SSTs have been conducted since 1957, but these analyses used analog calculation, less rigorous models, or focused on individual structures. As such, an integrated understanding of all of the SSTs has not been developed to modern expectations. In support of this effort, other milestones will address the visual inspection of the tank concrete and the collection of concrete core samples from the tanks for analysis

  20. Enhanced pervaporative desulfurization by polydimethylsiloxane membranes embedded with silver/silica core-shell microspheres

    Pervaporative desulfurization based on membrane technology provides a promising alternative for removal of sulfur substances (as represented by thiophene) in fluid catalytic cracking (FCC) gasoline. The present study focused on the performance enhancement of polydimethylsiloxane (PDMS) membrane by incorporation of core-shell structured silver/silica microspheres. A silane coupling agent, N-[3-(trimethoxysily)propyl]-ethylenediamine (TSD), was used to chelate the Ag+ via its amino groups and attach the silver seeds onto the silica surface via condensation of its methoxyl groups. The resultant microspheres were characterized by Zeta-positron annihilation lifetime spectroscopy (ZetaPALS), inductively coupled plasmaoptical emission spectrophotometer (ICP), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The Ag+/SiO2-PDMS composite membranes were prepared by blending PDMS with the as-synthesized silver/silica microspheres. PALS analysis was used to correlate the apparent fractional free volume with permeation flux. The sorption selectivity towards thiophene was enhanced after incorporation of silver/silica microspheres due to the π-complexation between the silver on the microsphere surface and the thiophene molecules. The pervaporative desulfurization performance of the composite membrane was investigated using thiophene/n-octane mixture as a model gasoline. The composite membrane exhibited an optimum desulfurization performance with a permeation flux of 7.76 kg/(m2 h) and an enrichment factor of 4.3 at the doping content of 5%.

  1. Nucleus accumbens corticotropin-releasing factor increases cue-triggered motivation for sucrose reward: paradoxical positive incentive effects in stress?

    Schulkin Jay

    2006-04-01

    Full Text Available Abstract Background Corticotropin-releasing factor (CRF is typically considered to mediate aversive aspects of stress, fear and anxiety. However, CRF release in the brain is also elicited by natural rewards and incentive cues, raising the possibility that some CRF systems in the brain mediate an independent function of positive incentive motivation, such as amplifying incentive salience. Here we asked whether activation of a limbic CRF subsystem magnifies the increase in positive motivation for reward elicited by incentive cues previously associated with that reward, in a way that might exacerbate cue-triggered binge pursuit of food or other incentives? We assessed the impact of CRF microinjections into the medial shell of nucleus accumbens using a pure incentive version of Pavlovian-Instrumental transfer, a measure specifically sensitive to the incentive salience of reward cues (which it separates from influences of aversive stress, stress reduction, frustration and other traditional explanations for stress-increased behavior. Rats were first trained to press one of two levers to obtain sucrose pellets, and then separately conditioned to associate a Pavlovian cue with free sucrose pellets. On test days, rats received microinjections of vehicle, CRF (250 or 500 ng/0.2 μl or amphetamine (20 μg/0.2 μl. Lever pressing was assessed in the presence or absence of the Pavlovian cues during a half-hour test. Results Microinjections of the highest dose of CRF (500 ng or amphetamine (20 μg selectively enhanced the ability of Pavlovian reward cues to trigger phasic peaks of increased instrumental performance for a sucrose reward, each peak lasting a minute or so before decaying after the cue. Lever pressing was not enhanced by CRF microinjections in the baseline absence of the Pavlovian cue or during the presentation without a cue, showing that the CRF enhancement could not be explained as a result of generalized motor arousal, frustration or stress

  2. Flow mechanism and heat transfer enhancement in longitudinal-flow tube bundle of shell-and-tube heat exchanger

    2009-01-01

    The flow disturbance and heat transfer mechanism in the tube bundle of rod baffle shell-and-tube heat exchanger were analyzed, on the basis of which and combined with the concept of heat transfer enhancement in the core flow, a new type of shell-and-tube heat exchanger with combination of rod and van type spoiler was designed. Corresponding mathematical and physical models on the shell side about the new type heat exchanger were established, and fluid flow and heat transfer characteristics were numerically analyzed. The simulation results showed that heat transfer coefficient of the new type of heat exchanger approximated to that of rod baffle heat exchanger, but flow pressure drop was much less than the latter, indicating that comprehensive performance of the former is superior to that of the latter. Compared with rod baffle heat exchanger, heat transfer coefficient of the heat exchanger under investigation is higher under same pressure drop, especially under the high Reynolds numbers.

  3. Complete Au@ZnO core-shell nanoparticles with enhanced plasmonic absorption enabling significantly improved photocatalysis.

    Sun, Yiqiang; Sun, Yugang; Zhang, Tao; Chen, Guozhu; Zhang, Fengshou; Liu, Dilong; Cai, Weiping; Li, Yue; Yang, Xianfeng; Li, Cuncheng

    2016-05-19

    Nanostructured ZnO exhibits high chemical stability and unique optical properties, representing a promising candidate among photocatalysts in the field of environmental remediation and solar energy conversion. However, ZnO only absorbs the UV light, which accounts for less than 5% of total solar irradiation, significantly limiting its applications. In this article, we report a facile and efficient approach to overcome the poor wettability between ZnO and Au by carefully modulating the surface charge density on Au nanoparticles (NPs), enabling rapid synthesis of Au@ZnO core-shell NPs at room temperature. The resulting Au@ZnO core-shell NPs exhibit a significantly enhanced plasmonic absorption in the visible range due to the Au NP cores. They also show a significantly improved photocatalytic performance in comparison with their single-component counterparts, i.e., the Au NPs and ZnO NPs. Moreover, the high catalytic activity of the as-synthesized Au@ZnO core-shell NPs can be maintained even after many cycles of photocatalytic reaction. Our results shed light on the fact that the Au@ZnO core-shell NPs represent a promising class of candidates for applications in plasmonics, surface-enhanced spectroscopy, light harvest devices, solar energy conversion, and degradation of organic pollutants. PMID:27160795

  4. One-pot synthesis of Pd-Pt@Pd core-shell nanocrystals with enhanced electrocatalytic activity for formic acid oxidation

    Yuan, Qiang

    2014-01-01

    Well-defined Pd-Pt@Pd core-shell nanocrystals with a Pd-Pt alloy core and a conformal Pd shell of ~2-3 nm were directly synthesized through a one-pot, aqueous solution approach without any preformed Pd or Pt seeds. These Pd-Pt@Pd core-shell nanocrystals show an enhanced electrocatalytic activity for formic acid oxidation compared with commercial Pd black. This journal is © 2014 The Royal Society of Chemistry.

  5. Enhanced thermal stability of functionally graded sandwich cylindrical shells by shape memory alloys

    Asadi, H.; Akbarzadeh, A. H.; Chen, Z. T.; Aghdam, M. M.

    2015-04-01

    The present paper deals with the nonlinear thermal instability of geometrically imperfect sandwich cylindrical shells under uniform heating. The sandwich shells are made of a shape memory alloy (SMA)-fiber-reinforced composite and functionally graded (FG) face sheets (FG/SMA/FG). The Brinson phenomenological model is used to express the constitutive characteristics of SMA fibers. The governing equations are established within the framework of the third-order shear deformation shell theory by taking into account the von Karman geometrical nonlinearity and initial imperfection. The material properties of constituents are assumed to be temperature dependent. The Galerkin technique is utilized to derive expressions of the bifurcation points and bifurcation paths of the sandwich cylindrical shells. Using the developed closed-form solutions, extensive numerical results are presented to provide an insight into the influence of the SMA fiber volume fraction, SMA pre-strain, core thickness, non-homogeneity index, geometrical imperfection, geometry parameters of sandwich shells and temperature dependency of materials on the stability of shells. The results reveal that proper application of SMA fibers postpones the thermal bifurcation point and dramatically decreases thermal post-buckling deflection. Moreover, the induced tensile recovery stress of SMA fibers could also stabilize the geometrically imperfect shells during the inverse martensite phase transformation.

  6. Enhanced Near-Infrared Fluorescence from Dye-Doped Core-Shell Ag/SiO2 Nanowires

    Li, Min; Zhou, Zhang-Kai; Zhai, Yue-Ying; Song, Hao; Zhang, Zong-Suo; Li, Xing; Yu, Xue-Feng

    We have studied the increase of the radiative decay rate of heptamethine cyanine NIR laser dye within core-shell Ag/SiO2 nanowires. The photoluminescence intensity and lifetime of the heptamethine cyanine dye are affected by the Ag nanowires. Both the photoluminescence intensity and the decay rate of the heptamethine cyanine dye are greatly enhanced by the Ag nanostructures and are caused by the interactions between the excited-state fluorophore and the local electric field near the metal particles.

  7. Enhanced charge storage capability of Ge/GeO2 core/shell nanostructure

    A Ge/GeO2 core/shell nanostructure embedded in an Al2O3 gate dielectrics matrix was produced. A larger memory window with good data retention was observed in the fabricated metal-insulator-semiconductor (MIS) capacitor for Ge/GeO2 core/shell nanoparticles compared to Ge nanoparticles only, which is due to the high percentage of defects located on the surface and grain boundaries of the GeO2 shell. We believe that the findings presented here provide physical insight and offer useful guidelines to controllably modify the charge storage properties of indirect semiconductors through defect engineering

  8. Facile Synthesis of Yolk/Core-Shell Structured TS-1@Mesosilica Composites for Enhanced Hydroxylation of Phenol

    Zou, Houbing

    2015-12-14

    © 2015 by the authors. In the current work, we developed a facile synthesis of yolk/core-shell structured TS-1@mesosilica composites and studied their catalytic performances in the hydroxylation of phenol with H2O2 as the oxidant. The core-shell TS-1@mesosilica composites were prepared via a uniform coating process, while the yolk-shell TS-1@mesosilica composite was prepared using a resorcinol-formaldehyde resin (RF) middle-layer as the sacrificial template. The obtained materials were characterized by X-ray diffraction (XRD), N2 sorption, Fourier transform infrared spectoscopy (FT-IR) UV-Visible spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The characterization results showed that these samples possessed highly uniform yolk/core-shell structures, high surface area (560–700 m2 g−1) and hierarchical pore structures from oriented mesochannels to zeolite micropores. Importantly, owing to their unique structural properties, these composites exhibited enhanced activity, and also selectivity in the phenol hydroxylation reaction.

  9. Core-shell microcapsules of solid lipid nanoparticles and mesoporous silica for enhanced oral delivery of curcumin.

    Kim, Sanghoon; Diab, Roudayna; Joubert, Olivier; Canilho, Nadia; Pasc, Andreea

    2016-04-01

    Newly designed microcapsules (MC) combining a core of solid lipid nanoparticle (SLN) and a mesoporous silica shell have been developed and explored as oral delivery system of curcumin (CU). CU-loaded MC (MC-CU) are 2μm sized and have a mesoporous silica shell of 0.3μm thickness with a wormlike structure as characterized by small angle X-ray scattering (SAXS), nitrogen adsorption/desorption and transmission electron microscopy (TEM) measurements. It was found that SLN acts as reservoir of curcumin while the mesoporous shell insures the protection and the controlled release of the drug. MC-CU displayed a pH-dependent in vitro release profile with marked drug retention at pH 2.8. Neutral red uptake assay together with confocal laser scanning microscopy (CLSM) showed a good cell tolerance to MC-CU at relatively high concentration of inert materials. Besides, the cell-uptake test revealed that fluorescent-MC were well internalized into Caco-2 cells, confirming the possibility to use MC for gut cells targeting. These findings suggest that organic core-silica shell microcapsules are promising drug delivery systems with enhanced bioavailability for poorly soluble drugs. PMID:26752213

  10. Coercivity enhancement in Ce-Fe-B based magnets by core-shell grain structuring

    Ito, M.; Yano, M.; Sakuma, N.; Kishimoto, H.; Manabe, A.; Shoji, T.; Kato, A.; Dempsey, N. M.; Givord, D.; Zimanyi, G. T.

    2016-05-01

    Ce-based R2Fe14B (R= rare-earth) nano-structured permanent magnets consisting of (Ce,Nd)2Fe14B core-shell grains separated by a non-magnetic grain boundary phase, in which the relative amount of Nd to Ce is higher in the shell of the magnetic grain than in its core, were fabricated by Nd-Cu infiltration into (Ce,Nd)2Fe14B hot-deformed magnets. The coercivity values of infiltrated core-shell structured magnets are superior to those of as-hot-deformed magnets with the same overall Nd content. This is attributed to the higher value of magnetocrystalline anisotropy of the shell phase in the core-shell structured infiltrated magnets compared to the homogeneous R2Fe14B grains of the as-hot-deformed magnets, and to magnetic isolation of R2Fe14B grains by the infiltrated grain boundary phase. First order reversal curve (FORC) diagrams suggest that the higher anisotropy shell suppresses initial magnetization reversal at the edges and corners of the R2Fe14B grains.

  11. Cu-Ag core-shell nanoparticles with enhanced oxidation stability for printed electronics

    Lee, Changsoo; Kim, Na Rae; Koo, Jahyun; Jong Lee, Yung; Lee, Hyuck Mo

    2015-11-01

    In this work, we synthesized uniform Cu-Ag core-shell nanoparticles using a facile two-step process that consists of thermal decomposition and galvanic displacement methods. The core-shell structure of these nanoparticles was confirmed through characterization using transmission electron microscopy, energy-dispersive spectroscopy, and x-ray diffraction. Furthermore, we investigated the oxidation stability of the Cu-Ag core-shell nanoparticles in detail. Both qualitative and quantitative x-ray photoelectron spectroscopy analyses confirm that the Cu-Ag core-shell nanoparticles have considerably higher oxidation stability than Cu nanoparticles. Finally, we formulated a conductive ink using the synthesized nanoparticles and coated it onto glass substrates. Following the sintering process, we compared the resistivity of the Cu-Ag core-shell nanoparticles with that of the Cu nanoparticles. The results of this study clearly show that the Cu-Ag core-shell nanoparticles can potentially be used as an alternative to Ag nanoparticles because of their superior oxidation stability and electrical properties.

  12. Optimization of metal-enhanced fluorescence by different concentrations of gold-silica core-shell nanoparticles

    Chen, Jiawei; Wang, Kai; Wu, Ke; Qian, Lihua; Long, Hua; Wang, Bing; Lu, Peixiang

    2015-08-01

    Colloidal solutions of Au/SiO2 core-shell nanoparticles (NPs) are synthesized. The diameters of Au core are 40 nm, 60 nm, 80 nm and 110 nm and the thickness of SiO2 shell is 20 nm. The metal-enhanced fluorescence of CdTe quantum dots (QDs) in aqueous solutions is studied by mixing the Au/SiO2 NPs colloidal solutions with different concentrations. As the molar ratio of the Au/SiO2 NPs and the CdTe QDs increases, the fluorescence enhancement factor grows rapidly because of the plasmonic enhancement, and then a reduction of the enhancement factor is observed because of the absorption of Au/SiO2 NPs. The largest fluorescence enhancement factor of 8 is obtained at the optimal molar ratio, when the surface plasmon resonance of the Au/SiO2 NPs (60 nm) matches the emission peak of the CdTe QDs. The results of our theoretical analysis support the experimental results.

  13. A High-Fat Meal, or Intraperitoneal Administration of a Fat Emulsion, Increases Extracellular Dopamine in the Nucleus Accumbens

    Hoebel, Bartley G.; Barson, Jessica R.; Pedro Rada; Leibowitz, Sarah F.; Avena, Nicole M.

    2012-01-01

    Evidence links dopamine (DA) in the nucleus accumbens (NAc) shell to the ingestion of palatable diets. Less is known, however, about the specific relation of DA to dietary fat and circulating triglycerides (TG), which are stimulated by fat intake and promote overeating. The present experiments tested in Sprague-Dawley rats whether extracellular levels of NAc DA increase in response to acute access to fat-rich food or peripheral injection of a fat emulsion and, if so, whether this is related t...

  14. Hampered long-term depression and thin spine loss in the nucleus accumbens of ethanol-dependent rats

    Spiga, S.; Talani, G; Mulas, G.; Licheri, V; Fois, GR; Muggironi, G; Masala, N; Cannizzaro, C; Biggio, G; E. Sanna; Diana, M.

    2014-01-01

    This paper examines the intimate neuroarchitecture of the nucleus accumbens shell region and how it affects synaptic plasticity in alcohol-dependent rats. To do so, a simultaneous morphometrical/immunofluorescence method was applied to visualize various types of dendritic spines and patch-clamp techniques to detect changes in synaptic currents. Using these tools, we show a selective loss of “long thin” spines accompanied by an impaired long-term depression (LTD) in alcohol-dependent rats. Dop...

  15. Desire and Dread from the Nucleus Accumbens: Cortical Glutamate and Subcortical GABA Differentially Generate Motivation and Hedonic Impact in the Rat

    Faure, Alexis; Richard, Jocelyn M.; Berridge, Kent C.

    2010-01-01

    Background GABAergic signals to the nucleus accumbens (NAc) shell arise from predominantly subcortical sources whereas glutamatergic signals arise mainly from cortical-related sources. Here we contrasted GABAergic and glutamatergic generation of hedonics versus motivation processes, as a proxy for comparing subcortical and cortical controls of emotion. Local disruptions of either signals in medial shell of NAc generate intense motivated behaviors corresponding to desire and/or dread, along a ...

  16. Effect of MK-801 on the development of nicotine sensitization of nucleus accumbens dopamine release

    We have previously found that MK-801, a noncompetitive NMDA receptor antagonist, prevents behavioral sensitization to nicotine. This study aimed to investigate the effect of MK-801 on a neurochemical component of nicotine sensitization by evaluating the effect of the drug on nicotine sensitization of nucleus accumbens dopamine (DA) release. Sprague-Dawley rats were pretreated with MK-801 (0.3 mg/kg, i.p.) or saline 30 min before injection of nicotine (0.4 mg/kg, s.c., once daily) for 7 consecutive days. Twenty-four hours after the last drug injection, animals were challenged with local perfusion of 5 mM nicotine into the shell of nucleus accumbens and DA release was monitored using in vivo microdialysis. In rats pretreated with chronic nicotine, local nicotine challenge induced a greater increase of accumbal DA release than in saline-treated animals (maximal DA response 969 ± 235% (mean ± SEM) of basal level vs. 520 ± 93%, P < 0.05). Co-administration of MK-801 with nicotine attenuated an increase of DA release elicited by local nicotine challenge, compared with nicotine alone (maximal DA response 427 ± 83% of basal level vs. 969 ± 235%, P < 0.01). These results suggest that MK-801 blocks the development of nicotine sensitization of nucleus accumbens DA release, further supporting the involvement of NMDA receptors in the development of behavioral sensitization to nicotine

  17. Complete Au@ZnO core-shell nanoparticles with enhanced plasmonic absorption enabling significantly improved photocatalysis

    Sun, Yiqiang; Sun, Yugang; Zhang, Tao; Chen, Guozhu; Zhang, Fengshou; Liu, Dilong; Cai, Weiping; Li, Yue; Yang, Xianfeng; Li, Cuncheng

    2016-05-01

    Nanostructured ZnO exhibits high chemical stability and unique optical properties, representing a promising candidate among photocatalysts in the field of environmental remediation and solar energy conversion. However, ZnO only absorbs the UV light, which accounts for less than 5% of total solar irradiation, significantly limiting its applications. In this article, we report a facile and efficient approach to overcome the poor wettability between ZnO and Au by carefully modulating the surface charge density on Au nanoparticles (NPs), enabling rapid synthesis of Au@ZnO core-shell NPs at room temperature. The resulting Au@ZnO core-shell NPs exhibit a significantly enhanced plasmonic absorption in the visible range due to the Au NP cores. They also show a significantly improved photocatalytic performance in comparison with their single-component counterparts, i.e., the Au NPs and ZnO NPs. Moreover, the high catalytic activity of the as-synthesized Au@ZnO core-shell NPs can be maintained even after many cycles of photocatalytic reaction. Our results shed light on the fact that the Au@ZnO core-shell NPs represent a promising class of candidates for applications in plasmonics, surface-enhanced spectroscopy, light harvest devices, solar energy conversion, and degradation of organic pollutants.Nanostructured ZnO exhibits high chemical stability and unique optical properties, representing a promising candidate among photocatalysts in the field of environmental remediation and solar energy conversion. However, ZnO only absorbs the UV light, which accounts for less than 5% of total solar irradiation, significantly limiting its applications. In this article, we report a facile and efficient approach to overcome the poor wettability between ZnO and Au by carefully modulating the surface charge density on Au nanoparticles (NPs), enabling rapid synthesis of Au@ZnO core-shell NPs at room temperature. The resulting Au@ZnO core-shell NPs exhibit a significantly enhanced plasmonic

  18. Enhanced performance of core-shell structured polyaniline at helical carbon nanotube hybrids for ammonia gas sensor

    Tian, Xin; Wang, Qiang; Chen, Xiangnan; Yang, Weiqing; Xu, Xiaoling, E-mail: zwzhou@at-c.net, E-mail: bihan-2001@163.com; Jiang, Man; Zhou, Zuowan, E-mail: zwzhou@at-c.net, E-mail: bihan-2001@163.com [Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Wu, Zuquan [School of Information Science and Technology, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)

    2014-11-17

    A core-shell structured hybrid of polyaniline at helical carbon nanotubes was synthesized using in situ polymerization, which the helical carbon nanotubes were uniformly surrounded by a layer of polyaniline nanorods array. More interestingly, repeatable responses were experimentally observed that the sensitivity to ammonia gas of the as-prepared helical shaped core-shell hybrid displays an enhancement of more than two times compared to those of only polyaniline or helical carbon nanotubes sensors because of the peculiar structures with high surface area. This kind of hybrid comprising nanorod arrays of conductive polymers covering carbon nanotubes and related structures provide a potential in sensors of trace gas detection for environmental monitoring and safety forecasting.

  19. Enhanced performance of core-shell structured polyaniline at helical carbon nanotube hybrids for ammonia gas sensor

    A core-shell structured hybrid of polyaniline at helical carbon nanotubes was synthesized using in situ polymerization, which the helical carbon nanotubes were uniformly surrounded by a layer of polyaniline nanorods array. More interestingly, repeatable responses were experimentally observed that the sensitivity to ammonia gas of the as-prepared helical shaped core-shell hybrid displays an enhancement of more than two times compared to those of only polyaniline or helical carbon nanotubes sensors because of the peculiar structures with high surface area. This kind of hybrid comprising nanorod arrays of conductive polymers covering carbon nanotubes and related structures provide a potential in sensors of trace gas detection for environmental monitoring and safety forecasting

  20. Control of nucleus accumbens activity with neurofeedback

    Greer, Stephanie M.; Trujillo, Andrew J.; Glover, Gary H.; Knutson, Brian

    2014-01-01

    The nucleus accumbens (NAcc) plays critical roles in healthy motivation and learning, as well as in psychiatric disorders (including schizophrenia and attention deficit hyperactivity disorder). Thus, techniques that confer control of NAcc activity might inspire new therapeutic interventions. By providing second-to-second temporal resolution of activity in small subcortical regions, functional magnetic resonance imaging (fMRI) can resolve online changes in NAcc activity, which can then be pres...

  1. α4-Containing GABAA Receptors in the Nucleus Accumbens Mediate Moderate Intake of Alcohol

    Rewal, Mridula; Jurd, Rachel; Gill, T. Michael; He, Dao-Yao; Ron, Dorit; Janak, Patricia H.

    2009-01-01

    Alcohol has subjective and behavioral effects at the pharmacological levels typically reached during the consumption of one or two alcoholic drinks. Here we provide evidence that an α4-subunit-containing gamma-amino-butyric acid A (GABAA) receptor contributes to the consumption of low-to-moderate levels of alcohol. Using viral-mediated RNA-interference (RNAi), we found that reduced expression of the α4 subunit in the nucleus accumbens (NAc) shell of rats decreased their free consumption of an...

  2. Li+ ions doping core–shell nanostructures: An approach to significantly enhance upconversion luminescence of lanthanide-doped nanocrystals

    Highlights: • A new strategy was adopted to enhance luminescence intensity of UCNPs. • The mechanism for the luminescence intensity enhancement of UCNPs was discussed. • Significant enhancement of UC emission in β-NaGdF4:Ln3+ nanocrystals was observed. - Abstract: Currently, enhancing luminescence efficiency of upconversion nanoparticles (UCNPs) has still been a challenging topic in despite of many efforts to improve UC luminescence. In this paper, a new strategy to enhance UC emission has been described based on coupling of Li+ ions doping with growth an inert shell. Significant enhancement of upconversion (UC) luminescence intensity of lanthanide-doped nanoparticles was observed under synergistic effect of internal adjustment and external approach. In addition, the mechanism for the luminescence enhancement of UCNPs has been discussed. Our results suggest that this UC enhancement strategy, proven here in NaGdF4 nanoparticles, could be extended to other lanthanide-doped nanocrystal systems for applications ranging from luminescent biological labels to volumetric three-dimensional displays

  3. Evaluation of the Interaction between NMDA Receptors of Nucleus Accumbens and Muscarinic Receptors in Memory

    Saba Taheri

    2013-02-01

    Full Text Available Background and Objectives: Whereas studies have indicated the interaction between NMDA and cholinergic systems, this study was performed with the aim of determining the role of NMDA receptors in the nucleus accumbens (NAc in scopolamine-induced amnesia.Methods: In this study, at first rats were anesthetized with intra-peritoneal injection of ketamine hydrochloride plus xylazine, and then placed in a stereotaxic apparatus. Two stainless-steel cannulas were placed 2mm above nucleus accumbens shell. All animals were allowed to recover for one week, before beginning the behavioral testing. Then, animals were trained in a step-through type inhibitory avoidance task. The drugs were injected after successful training and before testing. The animals were tested 24h after training, and the step-through latency time was measured as the memory criterion in male Wistar rats. One-way analysis of variance and Tukey’s test were used for analysis of the data. p<0.05 was considered statistically significant.Results: Intra-nucleus accumbens (intra-NAc injection of scopolamine or NMDA caused impairment in memory in rats. Although, co-administration of an ineffective dose of NMDA with an ineffective dose of scopolamine had no significant effect on memory performance, effective doses of NMDA prevented the amnesic effect of scopolamine on inhibitory avoidance memory. On the other hand, intra-NAc injection of NMDA receptor antagonist, i.e., MK-801 caused no change in memory performance by itself, and its co-administration with an effective dose of scopolamine could not prevent the impairing effect of the latter drug. Conclusion: The finding of this study indicated that NMDA receptors in the nucleus accumbens are involved in the modulation of scopolamine-induced amnesia.

  4. High-performance asymmetric supercapacitors based on core/shell cobalt oxide/carbon nanowire arrays with enhanced electrochemical energy storage

    Graphical abstract: - Highlights: • We prepared a self-supported porous Co3O4/C core/shell nanowire array. • Core/shell nanowire array showed high pseudo-capacitive properties. • Core/shell array structure was favorable for fast ion and electron transfer. - Abstract: High-reactivity electrode materials are indispensible for developing high-performance electrochemical energy storage devices. Herein, we report self-supported core/shell Co3O4/C nanowire arrays by using hydrothermal synthesis and chemical vapor deposition methods. A uniform and thin carbon shell is coated on the surface of Co3O4 nanowire forming core/shell nanowires with diameters of ∼100 nm. Asymmetric supercapacitors have been assembled with the core/shell Co3O4/C nanowire arrays as the positive electrode and activated carbon (AC) as the negative electrode. The core/shell Co3O4/C nanowire arrays exhibit a specific capacity of 116 mAh g−1 at the working current of 100 mA (4 A g−1), and a long cycle life along with ∼ 92% retention after 8000 cycles at 4 A g−1, higher than the unmodified Co3O4 nanowire arrays (81 mAh g−1 at 4 A g−1). The introduction of uniform carbon layer into the core/shell structure is favorable for the enhancement of supercapacitor due to the improved electrical conductivity and reaction kinetics

  5. Core-Shell Al-Polytetrafluoroethylene (PTFE) Configurations to Enhance Reaction Kinetics and Energy Performance for Nanoenergetic Materials.

    Wang, Jun; Qiao, Zhiqiang; Yang, Yuntao; Shen, Jinpeng; Long, Zhang; Li, Zhaoqian; Cui, Xudong; Yang, Guangcheng

    2016-01-01

    The energy performance of solid energetic materials (Al, Mg, etc.) is typically restricted by a natural passivation layer and the diffusion-limited kinetics between the oxidizer and the metal. In this work, we use polytetrafluoroethylene (PTFE) as the fluorine carrier and the shielding layer to construct a new type of nano-Al based fuels. The PTFE shell not only prevents nano-Al layers from oxidation, but also assists in enhancing the reaction kinetics, greatly improving the stability and reactivity of fuels. An in situ chemical vapor deposition combined with the electrical explosion of wires (EEW) method is used to fabricate core-shell nanostructures. Studies show that by controlling the stoichiometric ratio of the precursors, the morphology of the PTFE shell and the energy performance can be easily tuned. The resultant composites exhibit superior energy output characters than that of their physically mixed Al/PTFE counterparts. This synthetic strategy might provide a general approach to prepare other high-energy fuels (Mg, Si). PMID:26612396

  6. Nucleus accumbens neuronal activity in freely behaving rats is modulated following acute and chronic methylphenidate administration

    Chong, Samuel L; Claussen, Catherine M; Dafny, Nachum

    2012-01-01

    Methylphenidate (MPD) is a psychostimulant that enhances dopaminergic neurotransmission in the central nervous system by using mechanisms similar to cocaine and amphetamine. The mode of action of brain circuitry responsible for an animal’s neuronal response to MPD is not fully understood. The nucleus accumbens (NAc) has been implicated in regulating the rewarding effects of psychostimulants. The present study used permanently implanted microelectrodes to investigate the acute and chronic effe...

  7. Experience-Dependent Effects of Cocaine Self-Administration/Conditioning on Prefrontal and Accumbens Dopamine Responses

    Ikegami, Aiko; Olsen, Christopher M; D’Souza, Manoranjan S.; Duvauchelle, Christine L.

    2007-01-01

    Experiments were performed to examine the effects of cocaine self-administration and conditioning experience on operant behavior, locomotor activity, and nucleus accumbens (NAcc) and prefrontal cortex (PFC) dopamine (DA) responses. Sensory cues were paired with alternating cocaine and nonreinforcement during 12 (limited training) or 40 (long-term training) daily operant sessions. After limited training, NAcc DA responses to cocaine were significantly enhanced in the presence of cocaine-associ...

  8. Facile synthesis of CdS/C core-shell nanospheres with ultrathin carbon layer for enhanced photocatalytic properties and stability

    Chen, Jing; Zhang, Fu; Zhao, Yu-Ling; Guo, Yan-Chuan; Gong, Peijun; Li, Zheng-Quan; Qian, Hai-Sheng

    2016-01-01

    In this work, we described a facile one-pot hydrothermal process developed to synthesize CdS/C core-shell nanospheres successfully. The as-prepared CdS/C core-shell nanospheres are with 100 nm in diameter and the amorphous carbon shell is with several nanometers in thickness. The phase, morphology and structures of the samples were investigated by X-ray power diffraction (XRD) analyses, field-emission scanning electron microscopy (FESEM, JEOL-6700F) and transmission electron microscopy (TEM, JEOL 3010); respectively. The as-prepared CdS/C core-shell nanospheres showed enhanced photocatalytic properties and photostability compared to the single counterpart of CdS nanospheres owing to the efficiently separation of photogenerated electrons (e-) and holes (h+) derived from the photocatalyst. In addition, the as-prepared CdS/C core-shell nanospheres might find wide application in wastewater treatment, solar cells, lithium ion batteries, etc.

  9. Heat Transfer Enhancement of Shell and Tube Heat Exchanger Using Conical Tapes.

    Dhanraj S.Pimple; Shreeshail.B.H; Amar Kulkarni

    2014-01-01

    This paper provides heat transfer and friction factor data for single -phase flow in a shell and tube heat exchanger fitted with a helical tape insert. In the double concentric tube heat exchanger, hot air was passed through the inner tube while the cold water was flowed through the annulus. The influences of the helical insert on heat transfer rate and friction factor were studied for counter flow, and Nusselt numbers and friction factor obtained were compared with previous data ...

  10. Enhanced adsorption of trivalent arsenic from water by functionalized diatom silica shells.

    Jianying Zhang

    Full Text Available The potential of porous diatom silica shells as a naturally abundant low-cost sorbent for the removal of arsenic in aqueous solutions was investigated in a batch study. The objective of this work was to chemically modify the silica shells of a diatom Melosira sp. with bifunctional (thiol and amino groups to effectively remove arsenic in its toxic As(III form (arsenite predominant in the aquatic environment. Sorption experiments with this novel sorbent were conducted under varying conditions of pH, time, dosage, and As(III concentration. A maximum adsorption capacity of 10.99 mg g-1 was achieved within 26 h for a solution containing 12 mg L-1 As(III at pH 4 and sorbent dosage of 2 g L-1. The functionalized diatom silica shells had a surface morphological change which was accompanied by increased pore size at the expense of reduced specific surface area and total pore volume. As(III adsorption was best fitted with the Langmuir-Freundlich model, and the adsorption kinetic data using pore surface diffusion model showed that both the external (film and internal (intraparticle diffusion can be rate-determining for As(III adsorption. Fourier transform infrared spectroscopy (FTIR indicated that the thiol and amino groups potentially responsible for As(III adsorption were grafted on the surface of diatom silica shells. X-ray photoelectron spectroscopy (XPS further verified that this unique sorbent proceeded via a chemisorption mechanism through the exchange between oxygen-containing groups of neutral As(III and thiol groups, and through the surface complexation between As(III and protonated nitrogen and hydroxyl groups. Results indicate that this functionalized bioadsorbent with a high As(III adsorption capacity holds promise for the treatment of As(III containing wastewater.

  11. Core–Shell Nanoparticle-Based Peptide Therapeutics and Combined Hyperthermia for Enhanced Cancer Cell Apoptosis

    Shah, Birju P.; Pasquale, Nicholas; De, Gejing; Tan, Tao; Ma, Jianjie; Lee, Ki-Bum

    2014-01-01

    Mitochondria-targeting peptides have garnered immense interest as potential chemotherapeutics in recent years. However, there is a clear need to develop strategies to overcome the critical limitations of peptides, such as poor solubility and the lack of target specificity, which impede their clinical applications. To this end, we report magnetic core–shell nanoparticle (MCNP)-mediated delivery of a mitochondria-targeting pro-apoptotic amphipathic tail-anchoring peptide (ATAP) to malignant bra...

  12. High performance of PbSe/PbS core/shell quantum dot heterojunction solar cells: short circuit current enhancement without the loss of open circuit voltage by shell thickness control

    Choi, Hyekyoung; Song, Jung Hoon; Jang, Jihoon; Mai, Xuan Dung; Kim, Sungwoo; Jeong, Sohee

    2015-10-01

    We fabricated heterojunction solar cells with PbSe/PbS core shell quantum dots and studied the precisely controlled PbS shell thickness dependency in terms of optical properties, electronic structure, and solar cell performances. When the PbS shell thickness increases, the short circuit current density (JSC) increases from 6.4 to 11.8 mA cm-2 and the fill factor (FF) enhances from 30 to 49% while the open circuit voltage (VOC) remains unchanged at 0.46 V even with the decreased effective band gap. We found that the Fermi level and the valence band maximum level remain unchanged in both the PbSe core and PbSe/PbS core/shell with a less than 1 nm thick PbS shell as probed via ultraviolet photoelectron spectroscopy (UPS). The PbS shell reduces their surface trap density as confirmed by relative quantum yield measurements. Consequently, PbS shell formation on the PbSe core mitigates the trade-off relationship between the open circuit voltage and the short circuit current density. Finally, under the optimized conditions, the PbSe core with a 0.9 nm thick shell yielded a power conversion efficiency of 6.5% under AM 1.5.We fabricated heterojunction solar cells with PbSe/PbS core shell quantum dots and studied the precisely controlled PbS shell thickness dependency in terms of optical properties, electronic structure, and solar cell performances. When the PbS shell thickness increases, the short circuit current density (JSC) increases from 6.4 to 11.8 mA cm-2 and the fill factor (FF) enhances from 30 to 49% while the open circuit voltage (VOC) remains unchanged at 0.46 V even with the decreased effective band gap. We found that the Fermi level and the valence band maximum level remain unchanged in both the PbSe core and PbSe/PbS core/shell with a less than 1 nm thick PbS shell as probed via ultraviolet photoelectron spectroscopy (UPS). The PbS shell reduces their surface trap density as confirmed by relative quantum yield measurements. Consequently, PbS shell formation on

  13. Ag@Au core-shell dendrites: a stable, reusable and sensitive surface enhanced Raman scattering substrate

    Jun Yin, Hong; Yang Chen, Zhao; Mei Zhao, Yong; Yang Lv, Ming; An Shi, Chun; Long Wu, Zheng; Zhang, Xin; Liu, Luo; Li Wang, Ming; Jun Xu, Hai

    2015-09-01

    Surface enhanced Raman scattering (SERS) substrate based on fabricated Ag@Au core-shell dendrite was achieved. Ag dendrites were grown on Si wafer by the hydrothermal corrosion method and Au nanofilm on the surface of Ag dendritic nanostructure was then fabricated by chemical reduction. With the help of sodium borohydride in water, Au surface absorbates such as thiophene, adenine, rhodamine, small anions (Br- and I-), and a polymer (PVP, poly(N-vinylpyrrolidone)) can be completely and rapidly removed. After four repeatable experiments, the substrate SERS function did not decrease at all, indicating that the Ag@Au dendrite should be of great significance to SERS application because it can save much resource. Six-month-duration stability tests showed that the Ag@Au core-shell dendrite substrate is much more stable than the Ag dendrite substrates. We have also experimented on fast detection of Cd2+ at 10-8  M concentration by decorating single-stranded DNA containing adenine and guanine bases on the surface of this Ag@Au dendrite. Finite-difference time-domain simulations were carried out to investigate the influence of Au nanolayer on Ag dendrites, which showed that the local electric fields and enhancement factor are hardly affected when a 4 nm Au nanolayer is coated on Ag dendrite surface.

  14. Fluorescence signals of core-shell quantum dots enhanced by single crystalline gold caps on silicon nanowires

    We use nanoscale (20-300 nm in diameter) single crystalline gold (Au)-caps on silicon nanowires (NWs) grown by the vapor-liquid-solid (VLS) growth mechanism to enhance the fluorescence photoluminescence (PL) signals of highly dilute core/shell CdSeTe/ZnS quantum dots (QDs) in aqueous solution (10-5 M). For NWs without Au-caps, as they appear, for example, after Au etching in aqua regia or buffered KI/I2-solution, essentially no fluorescence signal of the same diluted QDs could be observed. Fluorescence PL signals were measured using excitation with a laser wavelength of 633 nm. The signal enhancement by single crystalline, nanoscale Au-caps is discussed and interpreted based on finite element modeling (FEM).

  15. Deep-ultraviolet surface plasmon resonance of Al and Alcore/Al2O3shell nanosphere dimers for surface-enhanced spectroscopy

    The localized surface plasmon resonance properties of Al and Alcore/Al2O3shell nanosphere dimers with Al and Al core nanosphere radii of 20 nm and Al2O3 shell of 2 nm in the deep-ultraviolet region have been studied using the finite difference time domain method. The extinction spectra and the electric field distribution profiles of the two dimers for various gap distances between two individual nanospheres are compared with those of the corresponding monomers to reveal the extent of plasmon coupling. It is found that with the interparticle distance decreasing, a strong plasmon coupling between two Al or Alcore/Al2O3shell nanospheres is observed accompanied by a significant red shift in the extinction spectra at the parallel polarization direction of the incident light related to the dimer axis, while for the case of the perpendicular polarization direction, a weak plasmon coupling arises characterized by a slight blue shift in the extinction spectra. The electric field distribution profiles show that benefiting from the dielectric Al2O3 shell, the gap distance of Alcore/Al2O3shell nanosphere dimers can be tailored to < 1 nm scale and results in a very high electric field enhancement. The estimated surface-enhanced Raman scattering enhancement factors suggests that the Alcore/Al2O3shell nanosphere dimers with the gap of < 1 nm gave rise to an enhancement as high as 8.1 × 107 for interparticle gap = 0.5 nm. Our studies reveal that the Alcore/Al2O3shell nanosphere dimers may be promising substrates for surface-enhanced spectroscopy in the deep-ultraviolet region. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  16. Endocannabinoid-Mediated Plasticity in Nucleus Accumbens Controls Vulnerability to Anxiety after Social Defeat Stress.

    Bosch-Bouju, Clémentine; Larrieu, Thomas; Linders, Louisa; Manzoni, Olivier J; Layé, Sophie

    2016-08-01

    Chronic social defeat stress (CSDS) is a clinically relevant model of mood disorders. The relationship between the CSDS model and a physiologically pertinent paradigm of synaptic plasticity is not known. Here, we found that cluster analysis of the emotional behavior states of mice exposed to CSDS allowed their segregation into anxious and non-anxious groups. Endocannabinoid-mediated spike-timing dependent plasticity (STDP) in the nucleus accumbens was attenuated in non-anxious mice and abolished in anxious mice. Anxiety-like behavior in stressed animals was specifically correlated with their ability to produce STDP. Pharmacological enhancement of 2-arachidonoyl glycerol (2-AG) signaling in the nucleus accumbens normalized the anxious phenotype and STDP in anxious mice. These data reveal that endocannabinoid modulation of synaptic efficacy in response to a naturalistic activity pattern is both a molecular correlate of behavioral adaptability and a crucial factor in the adaptive response to chronic stress. PMID:27452462

  17. Estradiol in the Preoptic Area Regulates the Dopaminergic Response to Cocaine in the Nucleus Accumbens.

    Tobiansky, Daniel J; Will, Ryan G; Lominac, Kevin D; Turner, Jonathan M; Hattori, Tomoko; Krishnan, Krittika; Martz, Julia R; Nutsch, Victoria L; Dominguez, Juan M

    2016-06-01

    The sex-steroid hormone estradiol (E2) enhances the psychoactive effects of cocaine, as evidenced by clinical and preclinical studies. The medial preoptic area (mPOA), a region in the hypothalamus, is a primary neural locus for neuroendocrine integration, containing one of the richest concentrations of estrogen receptors in the CNS and also has a key role in the regulation of naturally rewarding behaviors. However, whether estradiol enhances the neurochemical response to cocaine by acting in the mPOA is still unclear. Using neurotoxic lesions and microdialysis, we examined whether the mPOA modulates cocaine-induced neurochemical activity in the nucleus accumbens. Tract tracing and immunohistochemical staining were used to determine whether projections from the mPOA to the ventral tegmental area (VTA) are sensitive to estrogen signaling. Finally, estradiol microinjections followed by microdialysis were used to determine whether estrogenic signaling in the mPOA modulates cocaine-induced changes of dopamine in the nucleus accumbens. Results showed that lesions of the mPOA or microinjections of estradiol directly into the mPOA increased cocaine-induced release of dopamine in the nucleus accumbens. Immunohistochemical analyses revealed that the mPOA modulates cocaine responsiveness via projections to both dopaminergic and GABAergic neurons in the VTA, and that these projections are sensitive to estrogenic stimulation. Taken together, these findings point to a novel estradiol-dependent pathway that modulates cocaine-induced neurochemical activity in the mesolimbic system. PMID:26647972

  18. Ubiquitous element approach to plasmonic enhanced photocatalytic water splitting: the case of Ti@TiO2 core-shell nanostructure

    We demonstrate a new approach to plasmonic enhanced photocatalytic water splitting by developing a novel core-shell Ti@TiO2 brush nanostructure where an elongated Ti nanorod forms a plasmonic core that concentrates light inside of a nanotubular anodic TiO2 shell. Following the ubiquitous element approach aimed at providing an enhanced device functionality without the usage of noble or rare earth elements, we utilized only inexpensive Ti to create a complex Ti@TiO2 nanostructure with an enhanced UV and Vis photocatalytic activity that emerges from the interplay between the surface plasmon resonance in the Ti core, Vis light absorption in the Ti-rich oxide layer at the Ti/TiO2 interface and UV light absorption in the nanotubular TiO2 shell. (paper)

  19. Epitaxial Growth of Lattice-Mismatched Core-Shell TiO2 @MoS2 for Enhanced Lithium-Ion Storage.

    Dai, Rui; Zhang, Anqi; Pan, Zhichang; Al-Enizi, Abdullah M; Elzatahry, Ahmed A; Hu, Linfeng; Zheng, Gengfeng

    2016-05-01

    Core-shell structured nanohybrids are currently of significant interest due to their synergetic properties and enhanced performances. However, the restriction of lattice mismatch remains a severe obstacle for heterogrowth of various core-shells with two distinct crystal structures. Herein, a controlled synthesis of lattice-mismatched core-shell TiO2 @MoS2 nano-onion heterostructures is successfully developed, using unilamellar Ti0.87 O2 nanosheets as the starting material and the subsequent epitaxial growth of MoS2 on TiO2 . The formation of these core-shell nano-onions is attributed to an amorphous layer-induced heterogrowth mechanism. The number of MoS2 layers can be well tuned from few to over ten layers, enabling layer-dependent synergistic effects. The core-shell TiO2 @MoS2 nano-onion heterostructures exhibit significantly enhanced energy storage performance as lithium-ion battery anodes. The approach has also been extended to other lattice-mismatched systems such as TiO2 @MoSe2 , thus suggesting a new strategy for the growth of well-designed lattice-mismatched core-shell structures. PMID:27062267

  20. (Gold core)/(titania shell) nanostructures for plasmon-enhanced photon harvesting and generation of reactive oxygen species

    Fang, Caihong

    2014-01-01

    Integration of gold and titania in a nanoscale core/shell architecture can offer large active metal/semiconductor interfacial areas and avoid aggregation and reshaping of the metal nanocrystal core. Such hybrid nanostructures are very useful for studying plasmon-enhanced/enabled processes and have great potential in light-harvesting applications. Herein we report on a facile route to (gold nanocrystal core)/(titania shell) nanostructures with their plasmon band synthetically variable from ∼700 nm to over 1000 nm. The coating method has also been applied to other mono- and bi-metallic Pd, Pt, Au nanocrystals. The gold/titania nanostructures have been employed as the scattering layer in dye-sensitized solar cells, with the resultant cells exhibiting a 13.3% increase in the power conversion efficiency and a 75% decrease in the scattering-layer thickness. Moreover, under resonant excitation, the gold/titania nanostructures can efficiently utilize low-energy photons to generate reactive oxygen species, including singlet oxygen and hydroxyl radicals.

  1. Enhanced upconversion luminescence through core/shell structures and its application for detecting organic dyes in opaque fishes.

    Hu, Pan; Wu, Xiaofeng; Hu, Shigang; Chen, Zenghui; Yan, Huanyuan; Xi, Zaifang; Yu, Yi; Dai, Gangtao; Liu, Yunxin

    2016-02-10

    Here, we report the enhanced upconversion luminescence of NaLuF4:18%Yb(3+),2%Er(3+) through core/shell structures. Among NaYF4, NaGdF4, and NaLuF4 shells, the first one presents the highest efficiency. These upconversion fluorescent nanoprobes with an oleic acid/PEG hybrid ligand can efficiently capture Rhodamine B (RB) and sodium fluorescein (SF) in opaque fishes to present their residues in vivo through luminescence resonant energy transfer (LRET) processes. It can be confirmed based on LRET technology that no RB is absorbed by opaque fishes after incubating in the aqueous solution of 1 μg ml(-1) RB for one day, while SF residue can be obviously detected after incubating in the aqueous solution of 1 μg ml(-1) SF for one day. The merit of this LRET technology with the upconversion nanoparticle (UCNP) donor is ascribed to the deep penetration depth of the infrared pumping laser and high signal to noise ratio. PMID:26806612

  2. Coating Pt-Ni Octahedra with Ultrathin Pt Shells to Enhance the Durability without Compromising the Activity toward Oxygen Reduction.

    Park, Jinho; Liu, Jingyue; Peng, Hsin-Chieh; Figueroa-Cosme, Legna; Miao, Shu; Choi, Sang-Il; Bao, Shixiong; Yang, Xuan; Xia, Younan

    2016-08-23

    We describe a new strategy to enhance the catalytic durability of Pt-Ni octahedral nanocrystals in the oxygen reduction reaction (ORR) by conformally depositing an ultrathin Pt shell on the surface. The Pt-Ni octahedra were synthesized according to a protocol reported previously and then employed directly as seeds for the conformal deposition of ultrathin Pt shells by introducing a Pt precursor dropwise at 200 °C. The amount of Pt precursor was adjusted relative to the number of Pt-Ni octahedra involved to obtain Pt-Ni@Pt1.5L octahedra of 12 nm in edge length for the systematic evaluation of their chemical stability and catalytic durability compared to Pt-Ni octahedra. Specifically, we compared the elemental compositions of the octahedra before and after treatment with acetic and sulfuric acids. We also examined their electrocatalytic stability toward the ORR through an accelerated durability test by using a rotating disk electrode method. Even after treatment with sulfuric acid for 24 h, the Pt-Ni@Pt1.5L octahedra maintained their original Ni content, whereas 11 % of the Ni was lost from the Pt-Ni octahedra. After 10 000 cycles of ORR, the mass activity of the Pt-Ni octahedra decreased by 75 %, whereas the Pt-Ni@Pt1.5L octahedra only showed a 25 % reduction. PMID:27460459

  3. Enhancement of the oxygen reduction on nitride stabilized pt-M (M=Fe, Co, and Ni) core–shell nanoparticle electrocatalysts

    Kuttiyiel, Kurian A.

    2015-04-01

    Given the harsh operating conditions in hydrogen/oxygen fuel cells, the stability of catalysts is one of the critical questions affecting their commercialization. We describe a distinct class of oxygen reduction (ORR) core–shell electrocatalysts comprised of nitride metal cores enclosed by thin Pt shells that is easily synthesized. The synthesis is reproducible and amenable to scale up. Our theoretical analysis and the experimental data indicate that metal nitride nanoparticle cores could significantly enhance the ORR activity as well as the durability of the core–shell catalysts as a consequence of combined geometrical, electronic and segregation effects on the Pt shells. In addition to its fuel cells application, this class of catalysts holds promise to significantly contribute in resolving the problem of platinum scarcity and furthermore indicates the guidelines for future research and development.

  4. Heat Transfer Enhancement of Shell and Tube Heat Exchanger Using Conical Tapes.

    Dhanraj S.Pimple

    2014-12-01

    Full Text Available This paper provides heat transfer and friction factor data for single -phase flow in a shell and tube heat exchanger fitted with a helical tape insert. In the double concentric tube heat exchanger, hot air was passed through the inner tube while the cold water was flowed through the annulus. The influences of the helical insert on heat transfer rate and friction factor were studied for counter flow, and Nusselt numbers and friction factor obtained were compared with previous data (Dittus 1930, Petukhov 1970, Moody 1944 for axial flows in the plain tube. The flow considered is in a low Reynolds number range between 2300 and 8800. A maximum percentage gain of 165% in heat transfer rate is obtained for using the helical insert in comparison with the plain tube.

  5. Biostability enhancement of oil core - polysaccharide multilayer shell via photoinitiator free thiol-ene 'click' reaction.

    Calcagno, Vincenzo; Vecchione, Raffaele; Sagliano, Angela; Carella, Antonio; Guarnieri, Daniela; Belli, Valentina; Raiola, Luca; Roviello, Antonio; Netti, Paolo A

    2016-06-01

    Layer-by-layer of polyelectrolytes has emerged as one of the easiest and most controlled techniques to deposit ultrathin polymer layers mainly driven by electrostatic interactions. However, this kind of interaction results to be weak and easily breakable in physiological environment. Here we report on the preparation of nanocapsules completely made of natural biomaterials: a lipophilic core (soybean oil and egg lecithin as surfactant) as nanometric template and a polysaccharide-based multilayer shell (glycol chitosan and heparin) covalently cross-linked. We first modified glycol chitosan with a thiol moiety and heparin with an alkene moiety, respectively, and then we built a polymer multilayer film with a covalent cross-linkage among layers, exploiting the light initiated thiol-ene reaction, known as click chemistry. We showed the possibility to perform the covalent cross-linkage without any photoinitiator or metal catalyst, thus avoiding cytotoxic effects and further purification steps. The so realized nanocapsules resulted to be stable and completely biocompatible and, therefore, of interest for the biotechnology fields, mainly for drug delivery. PMID:26962765

  6. Correction: Shell-isolated nanoparticle-enhanced Raman spectroscopy study of the adsorption behaviour of DNA bases on Au(111) electrode surfaces.

    Wen, Bao-Ying; Jin, Xi; Li, Yue; Wang, Ya-Hao; Li, Chao-Yu; Liang, Miao-Miao; Panneerselvam, Rajapandiyan; Xu, Qing-Chi; Wu, De-Yin; Yang, Zhi-Lin; Li, Jian-Feng; Tian, Zhong-Qun

    2016-06-21

    Correction for 'Shell-isolated nanoparticle-enhanced Raman spectroscopy study of the adsorption behaviour of DNA bases on Au(111) electrode surfaces' by Bao-Ying Wen et al., Analyst, 2016, DOI: 10.1039/c6an00180g. PMID:27082242

  7. 2D Ultrathin Core-shell Pd@Ptmonolayer Nanosheets: Defect-Mediated Thin Film Growth and Enhanced Oxygen Reduction Performance

    Wang, Wenxin

    2015-06-16

    An operational strategy for the synthesis of atomically smooth Pt skin by a defect-mediated thin film growth method is reported. Extended ultrathin core-shell structured Pd@Ptmonolayer nanosheets (thickness below 5 nm) exhibit a seven-fold enhancement in mass-activity and surprisingly good durability toward oxygen reduction reaction as compared with the commercial Pt/C catalyst.

  8. Limbic and cortical information processing in the nucleus accumbens

    Goto, Yukiori; Grace, Anthony A.

    2008-01-01

    The nucleus accumbens regulates goal-directed behaviors by integrating information from limbic structures and the prefrontal cortex. Here, we review recent studies in an attempt to provide an integrated view of the control of information processing in the nucleus accumbens in terms of the regulation of goal-directed behaviors and how disruption of these functions might underlie the pathological states in drug addiction and other psychiatric disorders. We propose a model that could account for...

  9. Shell Venster

    In the bi-monthly issues of 'Shell Venster' (window on Shell) attention is paid to the activities of the multinational petroleum company Shell Nederland and the Koninklijke/Shell Groep by means of non-specialist articles

  10. Ultrathin TiO2 layer coated-CdS spheres core-shell nanocomposite with enhanced visible-light photoactivity.

    Chen, Zhang; Xu, Yi-Jun

    2013-12-26

    Development of various strategies for controllable fabrication of core-shell nanocomposites (CSNs) with highly active photocatalytic performance has been attracting ever-increasing research attention. In particular, control of the ultrathin layer TiO2 shell in constructing CSNs in an aqueous phase is a significant but technologically challenging issue. Here, this paper demonstrates the interface assembly synthesis of CdS nanospheres@TiO2 core-shell photocatalyst via the electrostatic interaction of negatively charged water-stable titania precursor with positively charged CdS nanospheres (CdS NSPs), followed by the formation of the ultrathin-layer TiO2 shell through a facile refluxing process in aqueous phase. The as-formed CdS NSPs@TiO2 core-shell nanohybrid exhibits a high visible-light-driven photoactivity for selective transformation and reduction of heavy metal ions. The ultrathin TiO2 layer coated on CdS NSPs results in excellent light transmission property, enhanced adsorption capacity, and improved transfer of charge carriers and lifespan of photoinduced electron-hole pairs, which would prominently contribute to the significant photoactivity enhancement. It is anticipated that this facile aqueous-phase synthesis strategy could be extended to design a variety of more efficient CSN photocatalysts with controllable morphology toward target applications in diverse photoredox processes. PMID:24245797

  11. A thalamic input to the nucleus accumbens mediates opiate dependence.

    Zhu, Yingjie; Wienecke, Carl F R; Nachtrab, Gregory; Chen, Xiaoke

    2016-02-11

    Chronic opiate use induces opiate dependence, which is characterized by extremely unpleasant physical and emotional feelings after drug use is terminated. Both the rewarding effects of a drug and the desire to avoid withdrawal symptoms motivate continued drug use, and the nucleus accumbens is important for orchestrating both processes. While multiple inputs to the nucleus accumbens regulate reward, little is known about the nucleus accumbens circuitry underlying withdrawal. Here we identify the paraventricular nucleus of the thalamus as a prominent input to the nucleus accumbens mediating the expression of opiate-withdrawal-induced physical signs and aversive memory. Activity in the paraventricular nucleus of the thalamus to nucleus accumbens pathway is necessary and sufficient to mediate behavioural aversion. Selectively silencing this pathway abolishes aversive symptoms in two different mouse models of opiate withdrawal. Chronic morphine exposure selectively potentiates excitatory transmission between the paraventricular nucleus of the thalamus and D2-receptor-expressing medium spiny neurons via synaptic insertion of GluA2-lacking AMPA receptors. Notably, in vivo optogenetic depotentiation restores normal transmission at these synapses and robustly suppresses morphine withdrawal symptoms. This links morphine-evoked pathway- and cell-type-specific plasticity in the paraventricular nucleus of the thalamus to nucleus accumbens circuit to opiate dependence, and suggests that reprogramming this circuit holds promise for treating opiate addiction. PMID:26840481

  12. Enhanced bio-compatibility of ferrofluids of self-assembled superparamagnetic iron oxide-silica core-shell nanoparticles.

    Narayanan, T N; Mary, A P Reena; Swalih, P K Anas; Kumar, D Sakthi; Makarov, D; Albrecht, M; Puthumana, Jayesh; Anas, Abdulaziz; Anantharaman, M R

    2011-03-01

    Self-assembled magnetic colloidal suspensions are sought after by material scientists owing to its huge application potential. The biomedical applications of colloidal nanoparticles necessitate that they are biocompatible, non-interacting, monodispersed and hence the synthesis of such nanostructures has great relevance in the realm of nanoscience. Silica-coated superparamagnetic iron oxide nanoparticles based ferrofluids were prepared using polyethylene glycol as carrier fluid by employing a controlled co-precipitation technique followed by a modified sol-gel synthesis. A plausible mechanism for the formation of stable suspension of SiO2-coated Iron Oxide nanoparticles with a size of about 9 nm dispersed in polyethylene glycol (PEG) is proposed. Core-shell nature of the resultant SiO2-Iron Oxide nanocomposite was verified using transmission electron microscopy. Fourier transform-infrared spectroscopy studies were carried out to understand the structure and nature of chemical bonds. The result suggests that Iron Oxide exist in an isolated state inside silica matrix. Moreover, the presence of silanol bonds establishes the hydrophilic nature of silica shell confirming the formation of stable ferrofluid with PEG as carrier fluid. The magnetic characterization reveals the superparamagnetic behavior of the nanoparticles with a rather narrow distribution of blocking temperatures. These properties are not seen in ferrofluids prepared from Iron Oxide nanoparticles without SiO2 coating. The latter suggests the successful tuning of the inter-particle interactions preventing agglomeration of nanoparticles. Cytotoxicity studies on citric acid coated water based ferrofluid and silica-coated PEG-based ferrofluid were evaluated by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium chloride assay and it shows an enhanced compatibility for silica modified nanoparticles. PMID:21449334

  13. Synthesis and characterization of surface-enhanced Raman scattering tags with Ag/SiO2 core-shell nanostructures using reverse micelle technology.

    Gong, Ji-Lai; Jiang, Jian-Hui; Liang, Yi; Shen, Guo-Li; Yu, Ru-Qin

    2006-06-15

    A novel simplified method for synthesis of surface-enhanced Raman scattering tags has been reported. This synthesis method is based on reverse micelle technique using Igepal CO-520 as a surfactant and the mixed solution of silver nitrate and rhodamine dyes with isothiocyanate group as water pool followed by hydrazine hydrate reduction and TEOS polymerization leading to the formation of silica layer surrounding the silver core. Compared to the method reported in literature, the proposed methodology eliminates the necessity of vitrophilic pretreatment and makes it possible to complete all different processes including the preparation of silver nanoparticles, the conjugation of dye molecules and the formation of silica shell in the microreactor. The nanoparticle-based surface-enhanced Raman tags obtained are composed of silver core conjugated with rhodamine dyes and an encasing silica shell. Both the dyes themselves and the Ag/SiO2 core-shell nanoparticles without the encapsulation of dyes exhibit no Raman signals. However, the Ag/SiO2 core-shell nanoparticles exhibit strong Raman signals when encapsulated with these dyes. This is due to the appearance of fluorescence quenching and surface-enhanced Raman scattering effect resulting from the conjugation of dyes and silver core. The Raman tags were characterized using transmission electron microscopy (TEM), UV-visible absorption spectrometry, and Raman spectrometry. PMID:16457836

  14. Observation of enhanced chiral asymmetries in the inner-shell photoionization of uniaxially oriented methyloxirane enantiomers

    Tia, Maurice; Kastirke, Gregor; Gatzke, Janine; Kim, Hong-Keun; Trinter, Florian; Rist, Jonas; Hartung, Alexander; Trabert, Daniel; Siebert, Juliane; Henrichs, Kevin; Becht, Jasper; Zeller, Stefan; Gassert, Helena; Wiegandt, Florian; Wallauer, Robert; Kuhlins, Andreas; Schober, Carl; Bauer, Tobias; Wechselberger, Natascha; Burzynski, Phillip; Neff, Jonathan; Weller, Miriam; Metz, Daniel; Kircher, Max; Waitz, Markus; Williams, Joshua B; Schmidt, Lothar; Mueller, Anne D; Knie, Andre; Hans, Andreas; Ltaief, Ltaief Ben; Ehresmann, Arno; Berger, Robert; Fukuzawa, Hironobu; Ueda, Kiyoshi; Schmidt-Boecking, Horst; Doerner, Reinhard; Jahnke, Till; Demekhin, Philipp V; Schoeffler, Markus

    2016-01-01

    Most large molecules are chiral in their structure: they exist as two enantiomers, which are mirror images of each other. Whereas the rovibronic sublevels of two enantiomers are almost identical, it turns out that the photoelectric effect is sensitive to the absolute configuration of the ionized enantiomer - an effect termed Photoelectron Circular Dichroism (PECD). Our comprehensive study demonstrates that the origin of PECD can be found in the molecular frame electron emission pattern connecting PECD to other fundamental photophysical effects as the circular dichroism in angular distributions (CDAD). Accordingly, orienting a chiral molecule in space enhances the PECD by a factor of about 10.

  15. Palladium nanoparticles encapsulated in core-shell silica: A structured hydrogenation catalyst with enhanced activity for reduction of oxyanion water pollutants

    Wang, Yin

    2014-10-03

    Noble metal nanoparticles have been applied to mediate catalytic removal of toxic oxyanions and halogenated hydrocarbons in contaminated water using H2 as a clean and sustainable reductant. However, activity loss by nanoparticle aggregation and difficulty of nanoparticle recovery are two major challenges to widespread technology adoption. Herein, we report the synthesis of a core-shell-structured catalyst with encapsulated Pd nanoparticles and its enhanced catalytic activity in reduction of bromate (BrO3-), a regulated carcinogenic oxyanion produced during drinking water disinfection process, using 1 atm H2 at room temperature. The catalyst material consists of a nonporous silica core decorated with preformed octahedral Pd nanoparticles that were further encapsulated within an ordered mesoporous silica shell (i.e., SiO2@Pd@mSiO2). Well-defined mesopores (2.3 nm) provide a physical barrier to prevent Pd nanoparticle (6 nm) movement, aggregation, and detachment from the support into water. Compared to freely suspended Pd nanoparticles and SiO2@Pd, encapsulation in the mesoporous silica shell significantly enhanced Pd catalytic activity (by a factor of 10) under circumneutral pH conditions that are most relevant to water purification applications. Mechanistic investigation of material surface properties combined with Langmuir-Hinshelwood modeling of kinetic data suggest that mesoporous silica shell enhances activity by promoting BrO3- adsorption near the Pd active sites. The dual function of the mesoporous shell, enhancing Pd catalyst activity and preventing aggregation of active nanoparticles, suggests a promising general strategy of using metal nanoparticle catalysts for water purification and related aqueous-phase applications.

  16. ZnO@CdS Core-Shell Heterostructures: Fabrication, Enhanced Photocatalytic, and Photoelectrochemical Performance

    Ding, Meng; Yao, Nannan; Wang, Chenggang; Huang, Jinzhao; Shao, Minghui; Zhang, Shouwei; Li, Ping; Deng, Xiaolong; Xu, Xijin

    2016-04-01

    ZnO nanorods and ZnO@CdS heterostructures have been fabricated on carbon fiber cloth substrates via hydrothermal and electrochemical deposition. Their photocatalytic properties were investigated by measuring the degradation of methylene blue under ultraviolet light irradiation. The result illustrated that the photodegradation efficiency of ZnO@CdS heterostructures was better than that of pure ZnO nanorods, in which the rate constants were about 0.04629 and 0.02617 min-1. Furthermore, the photocurrent of ZnO@CdS heterostructures achieved 102 times enhancement than pure ZnO nanorods, indicating that more free carriers could be generated and transferred in ZnO@CdS heterostructures, which could be responsible for the increased photocatalytic performance.

  17. ZnO@CdS Core-Shell Heterostructures: Fabrication, Enhanced Photocatalytic, and Photoelectrochemical Performance.

    Ding, Meng; Yao, Nannan; Wang, Chenggang; Huang, Jinzhao; Shao, Minghui; Zhang, Shouwei; Li, Ping; Deng, Xiaolong; Xu, Xijin

    2016-12-01

    ZnO nanorods and ZnO@CdS heterostructures have been fabricated on carbon fiber cloth substrates via hydrothermal and electrochemical deposition. Their photocatalytic properties were investigated by measuring the degradation of methylene blue under ultraviolet light irradiation. The result illustrated that the photodegradation efficiency of ZnO@CdS heterostructures was better than that of pure ZnO nanorods, in which the rate constants were about 0.04629 and 0.02617 min(-1). Furthermore, the photocurrent of ZnO@CdS heterostructures achieved 10(2) times enhancement than pure ZnO nanorods, indicating that more free carriers could be generated and transferred in ZnO@CdS heterostructures, which could be responsible for the increased photocatalytic performance. PMID:27090656

  18. Diazepam alters cocaine self-administration, but not cocaine-stimulated locomotion or nucleus accumbens dopamine

    Maier, Esther Y.; Ledesma, Ramon T.; Seiwell, Andrew P.; Duvauchelle, Christine L.

    2008-01-01

    Cocaine is known to enhance nucleus accumbens dopamine (NAcc DA), serve as a positive reinforcer and produce negative effects, such as anxiety. The influence of diazepam on cocaine intake, cocaine-stimulated behavioral activity and NAcc DA was investigated using self-administration and experimenter-administered intravenous (i.v.) cocaine. In Experiment 1, rats were pretreated with diazepam (0.25 mg/kg) or saline (0.1 ml) 30 minutes prior to 20 daily 1-hr cocaine (0.75 mg/kg/inj) self-administ...

  19. Exploring type II microcalcifications in benign and premalignant breast lesions by shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS)

    Liang, Lijia; Zheng, Chao; Zhang, Haipeng; Xu, Shuping; Zhang, Zhe; Hu, Chengxu; Bi, Lirong; Fan, Zhimin; Han, Bing; Xu, Weiqing

    2014-11-01

    The characteristics of type II microcalcifications in fibroadenoma (FB), atypical ductal hyperplasia (ADH), and ductal carcinoma in situ (DCIS) breast tissues has been analyzed by the fingerprint features of Raman spectroscopy. Fresh breast tissues were first handled to frozen sections and then they were measured by normal Raman spectroscopy. Due to inherently low sensitivity of Raman scattering, Au@SiO2 shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) technique was utilized. A total number of 71 Raman spectra and 70 SHINERS spectra were obtained from the microcalcifications in benign and premalignant breast tissues. Principal component analysis (PCA) was used to distinguish the type II microcalcifications between these tissues. This is the first time to detect type II microcalcifications in premalignant (ADH and DCIS) breast tissue frozen sections, and also the first time SHINERS has been utilized for breast cancer detection. Conclusions demonstrated in this paper confirm that SHINERS has great potentials to be applied to the identification of breast lesions as an auxiliary method to mammography in the early diagnosis of breast cancer.

  20. Gd-based upconversion nanocarriers with yolk-shell structure for dual-modal imaging and enhanced chemotherapy to overcome multidrug resistance in breast cancer

    Pan, Yuanwei; Zhang, Ling'e.; Zeng, Leyong; Ren, Wenzhi; Xiao, Xueshan; Zhang, Jichao; Zhang, Lili; Li, Aiguo; Lu, Guangming; Wu, Aiguo

    2015-12-01

    Multidrug resistance (MDR) of cancers is still a major challenge, and it is very important to develop visualized nanoprobes for the diagnosis and treatment of drug resistant cancers. In this work, we developed a multifunctional delivery system based on DOX-encapsulated NaYF4:Yb/Er@NaGdF4 yolk-shell nanostructures for simultaneous dual-modal imaging and enhanced chemotherapy in drug resistant breast cancer. Using the large pore volume of the nanostructure, the delivery system had a high loading efficiency and excellent stability. Also, an in vitro and in vivo toxicity study showed the good biocompatibility of the as-prepared yolk-shell nanomaterials. Moreover, by nanocarrier delivery, the uptake of DOX could be greatly increased in drug resistant MCF-7/ADR cells. Compared with free DOX, the as-prepared delivery system enhanced the chemotherapy efficacy against MCF-7/ADR cells, indicating the excellent capability for overcoming MDR. Furthermore, core-shell NaYF4:Yb/Er@NaGdF4 improved the upconversion luminescence (UCL) performance, and the designed delivery system could also be applied for simultaneous UCL and magnetic resonance (MR) imaging, which could be a good candidate as a dual-modal imaging nanoprobe. Therefore, we developed a multifunctional yolk-shell delivery system, which could have potential applications as a visualized theranostic nanoprobe to overcome MDR in breast cancer.

  1. Synthesis, characterization and enhanced photocatalytic performance of Ag{sub 2}S-coupled ZnO/ZnS core/shell nanorods

    Liu, Shan [Tianjin Key Laboratory of Applied Catalysis Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Wang, Xitao, E-mail: wangxt@tju.edu.cn [Tianjin Key Laboratory of Applied Catalysis Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Zhao, Wenxi [Tianjin Academy of Environmental Sciences, Tianjin 300191 (China); Wang, Kang [Tianjin Key Laboratory of Applied Catalysis Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Sang, Huanxin [Tianjin Academy of Environmental Sciences, Tianjin 300191 (China); He, Zhong [Department of Chemical, Biological and Pharmaceutical Engineering, New Jersey Institute of Technology, Newark, NJ 07102 (United States)

    2013-08-15

    Highlights: •A new route was developed to synthetize Ag{sub 2}S-coupled ZnO/ZnS core/shell nanorods. •ZnO/ZnS–Ag{sub 2}S nanorods display enhanced photocatalytic activity for H{sub 2} evolution. •Dilute solution of glycerol is used as sacrificial reagent. •Ag{sub 2}S/ZnS molar ratio on the shell affects obviously the photocatalytic performance. -- Abstract: A series of composite photocatalysts comprised of ZnO nanorods core and ZnS–Ag{sub 2}S heterostructural shell layer with different Ag{sub 2}S/ZnS molar ratios have been synthesized via the combination of a low-temperature hydrothermal growth and cation exchange technique. The core/shell nanorods, with the diameters of about 150 nm and the lengths of ranging from a few 100 nm to several micrometers, were fabricated by coating the ZnO nanorods with a layer of ZnS and Ag{sub 2}S composite shell mainly consisting of nanocrystals with the diameters of about 5–8 nm. The characterization from SEM, TEM, EDX, XPS, and UV–Vis DRS reveals that the molar ratio of Ag{sub 2}S/ZnS in shell layer strongly affects the morphologies, distribution of components, photo absorption, and photocatalytic performance of the ZnO/ZnS–Ag{sub 2}S core/shell nanorods. Due to the coupling with low bandgap material Ag{sub 2}S, the ZnO/ZnS–Ag{sub 2}S nanorods have a much higher solar-simulated light absorption capability than that of ZnO/ZnS. As a result, the as-prepared ZnO/ZnS–Ag{sub 2}S nanocomposites exhibited much higher catalytic efficiency for the hydrogen production from glycerol aqueous solution. The superior photo absorption properties and photocatalytic performance of the ZnO/ZnS–Ag{sub 2}S core/shell nanorods may be ascribed to the heterostructure, which enhanced the separation of photo-induced electron–hole pairs.

  2. Fabrication of hydrophilic S/In2O3 core–shell nanocomposite for enhancement of photocatalytic performance under visible light irradiation

    Graphical abstract: - Highlights: • The elemental core–shell heterostructure was reported for the first time. • The hydrophilic core–shell S/In2O3 photocatalyst was prepared by ball milling. • The rate constant of 10% S/In2O3 is 11.6 and 13.5 times that of In2O3 and S. • The hydrophilicity and efficiently separation of carriers are major factor. - Abstract: Recently, elemental semiconductors as new photocatalysts excited by visible light have attracted great attention due to their potential applications for environmental remediation and clean energy generation. However, it is still a challenge to fabricate elemental photocatalysts with high activity and stability. In this paper, a straightforward ball-milling method was carried out to fabricate core–shell S/In2O3 nanocomposite photocatalyst with high performance. The photocatalyst was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), Brunauer–Emmett–Teller (BET) method, photoluminescence spectra (PL) and super-hydrophilic experiment. The results showed that In2O3 nanoparticles were successfully grown round of S blocks and formed core–shell heterostructures. The 10% S/In2O3 core–shell nanocomposite exhibited the highest photocatalytic activity for degradation of rhodamine B (RhB) under visible light irradiation. The reaction rate constant (k) of the 10% S/In2O3 core–shell nanocomposite is about 8.7 times as high as the sum of pure In2O3 and S because of the formation of core–shell S/In2O3 heterostructures, which might remedy the drawbacks of poor hydrophilicity of S, enhance visible light absorption and separate the photogenerated carriers efficiently. Furthermore, the mechanism of influence on the photocatalytic activity of the S/In2O3 core–shell nanocomposite was also discussed. It is anticipated that our work may open up a new

  3. Efficiency Enhanced Colloidal Mn-Doped Type II Core/Shell ZnSe/CdS Quantum Dot Sensitized Hybrid Solar Cells

    A. Jamshidi

    2015-01-01

    Full Text Available Colloidal Mn-doped ZnSe/CdS core/shell quantum dots (QDs are synthesized for the first time and employed as a strategy to boost the power conversion efficiency of quantum dot sensitized solar cells. By using Mn-doping as a band gap engineering tool for core/shell QDs an effective improvement of absorption spectra could be obtained. The mid-states generated by a proper Mn content alleviate carrier separation and enhance the electron injection rate, thus facilitating electron transport to the TiO2 substrate. It is demonstrated that a device constructed with 0.25% Mn-doped ZnSe/CdS leads to an enhancement of the electron injection rate and power conversion efficiency by 4 times and 1.3, respectively.

  4. File list: ALL.Neu.20.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  8. File list: Oth.Neu.20.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  9. File list: Oth.Neu.05.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  10. File list: Oth.Neu.10.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  11. File list: His.Neu.20.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  12. File list: NoD.Neu.20.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  13. File list: His.Neu.50.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  14. File list: NoD.Neu.10.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  15. File list: His.Neu.05.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  16. File list: Unc.Neu.10.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  17. File list: His.Neu.10.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  18. File list: ALL.Neu.10.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  19. File list: Pol.Neu.50.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  20. File list: NoD.Neu.05.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  1. File list: Unc.Neu.05.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  2. File list: Pol.Neu.20.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  3. File list: Oth.Neu.50.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  4. File list: Unc.Neu.20.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  5. File list: InP.Neu.05.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  6. File list: ALL.Neu.50.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  7. File list: ALL.Neu.05.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  8. File list: Unc.Neu.50.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  9. File list: InP.Neu.50.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  10. File list: Pol.Neu.05.AllAg.Nucleus_Accumbens [Chip-atlas[Archive

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  11. Pursuing shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) for concomitant detection of breast lesions and microcalcifications

    Zheng, Chao; Shao, Wanting; Paidi, Santosh Kumar; Han, Bing; Fu, Tong; Wu, Di; Bi, Lirong; Xu, Weiqing; Fan, Zhimin; Barman, Ishan

    2015-10-01

    Although tissue staining followed by morphologic identification remains the gold standard for diagnosis of most cancers, such determinations relying solely on morphology are often hampered by inter- and intra-observer variability. Vibrational spectroscopic techniques, in contrast, offer objective markers for diagnoses and can afford disease detection prior to alterations in cellular and extracellular architecture by furnishing a rapid ``omics''-like view of the biochemical status of the probed specimen. Here, we report a classification approach to concomitantly detect microcalcification status and local pathological state in breast tissue, featuring a combination of vibrational spectroscopy that focuses on the tumor and its microenvironment, and multivariate data analysis of spectral markers reflecting molecular expression. We employ the unprecedented sensitivity and exquisite molecular specificity offered by Au@SiO2 shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) to probe the presence of calcified deposits and distinguish between normal breast tissues, fibroadenoma, atypical ductal hyperplasia, ductal carcinoma in situ (DCIS), and invasive ductal carcinoma (IDC). By correlating the spectra with the corresponding histologic assessment, we developed partial least squares-discriminant analysis derived decision algorithm that provides excellent diagnostic power in the fresh frozen sections (overall accuracy of 99.4% and 93.6% using SHINs for breast lesions with and without microcalcifications, respectively). The performance of this decision algorithm is competitive with or supersedes that of analogous algorithms employing spontaneous Raman spectroscopy while enabling facile detection due to the considerably higher intensity of SHINERS. Our results pave the way for rapid tissue spectral pathology measurements using SHINERS that can offer a novel stain-free route to accurate and economical diagnoses without human interpretation.Although tissue staining

  12. Enhancement of Alkaline Protease Activity and Stability via Covalent Immobilization onto Hollow Core-Mesoporous Shell Silica Nanospheres

    Abdelnasser Salah Shebl Ibrahim

    2016-01-01

    Full Text Available The stability and reusability of soluble enzymes are of major concerns, which limit their industrial applications. Herein, alkaline protease from Bacillus sp. NPST-AK15 was immobilized onto hollow core-mesoporous shell silica (HCMSS nanospheres. Subsequently, the properties of immobilized proteases were evaluated. Non-, ethane- and amino-functionalized HCMSS nanospheres were synthesized and characterized. NPST-AK15 was immobilized onto the synthesized nano-supports by physical and covalent immobilization approaches. However, protease immobilization by covalent attachment onto the activated HCMSS–NH2 nanospheres showed highest immobilization yield (75.6% and loading capacity (88.1 μg protein/mg carrier and was applied in the further studies. In comparison to free enzyme, the covalently immobilized protease exhibited a slight shift in the optimal pH from 10.5 to 11.0, respectively. The optimum temperature for catalytic activity of both free and immobilized enzyme was seen at 60 °C. However, while the free enzyme was completely inactivated when treated at 60 °C for 1 h the immobilized enzyme still retained 63.6% of its initial activity. The immobilized protease showed higher Vmax, kcat and kcat/Km, than soluble enzyme by 1.6-, 1.6- and 2.4-fold, respectively. In addition, the immobilized protease affinity to the substrate increased by about 1.5-fold. Furthermore, the enzyme stability in various organic solvents was significantly enhanced upon immobilization. Interestingly, the immobilized enzyme exhibited much higher stability in several commercial detergents including OMO, Tide, Ariel, Bonux and Xra by up to 5.2-fold. Finally, the immobilized protease maintained significant catalytic efficiency for twelve consecutive reaction cycles. These results suggest the effectiveness of the developed nanobiocatalyst as a candidate for detergent formulation and peptide synthesis in non-aqueous media.

  13. Piezo-phototronic effect enhanced UV photodetector based on CuI/ZnO double-shell grown on flexible copper microwire.

    Liu, Jingyu; Zhang, Yang; Liu, Caihong; Peng, Mingzeng; Yu, Aifang; Kou, Jinzong; Liu, Wei; Zhai, Junyi; Liu, Juan

    2016-12-01

    In this work, we present a facile, low-cost, and effective approach to fabricate the UV photodetector with a CuI/ZnO double-shell nanostructure which was grown on common copper microwire. The enhanced performances of Cu/CuI/ZnO core/double-shell microwire photodetector resulted from the formation of heterojunction. Benefiting from the piezo-phototronic effect, the presentation of piezocharges can lower the barrier height and facilitate the charge transport across heterojunction. The photosensing abilities of the Cu/CuI/ZnO core/double-shell microwire detector are investigated under different UV light densities and strain conditions. We demonstrate the I-V characteristic of the as-prepared core/double-shell device; it is quite sensitive to applied strain, which indicates that the piezo-phototronic effect plays an essential role in facilitating charge carrier transport across the CuI/ZnO heterojunction, then the performance of the device is further boosted under external strain. PMID:27255901

  14. Piezo-phototronic effect enhanced UV photodetector based on CuI/ZnO double-shell grown on flexible copper microwire

    Liu, Jingyu; Zhang, Yang; Liu, Caihong; Peng, Mingzeng; Yu, Aifang; Kou, Jinzong; Liu, Wei; Zhai, Junyi; Liu, Juan

    2016-06-01

    In this work, we present a facile, low-cost, and effective approach to fabricate the UV photodetector with a CuI/ZnO double-shell nanostructure which was grown on common copper microwire. The enhanced performances of Cu/CuI/ZnO core/double-shell microwire photodetector resulted from the formation of heterojunction. Benefiting from the piezo-phototronic effect, the presentation of piezocharges can lower the barrier height and facilitate the charge transport across heterojunction. The photosensing abilities of the Cu/CuI/ZnO core/double-shell microwire detector are investigated under different UV light densities and strain conditions. We demonstrate the I- V characteristic of the as-prepared core/double-shell device; it is quite sensitive to applied strain, which indicates that the piezo-phototronic effect plays an essential role in facilitating charge carrier transport across the CuI/ZnO heterojunction, then the performance of the device is further boosted under external strain.

  15. Enhanced DSSCs efficiency via Cooperate co-absorbance (CdS QDs) and plasmonic core-shell nanoparticle (Ag@PVP)

    Amiri, Omid; Salavati-Niasari, Masoud; Bagheri, Samira; Yousefi, Amin Termeh

    2016-01-01

    This paper describes cooperate the co-absorbance (CdS QDs) and the plasmonic core-shell nanoparticles (Ag@PVP) of dye synthesized solar cells in which CdS QDs and Ag@PVP are incorporated into the TiO2 layer. Cooperative nanoparticles show superior behavior on enhancing light absorption in comparison with reference cells. Cooperated DSSC exhibits the best performance with the power conversion efficiency of 7.64% which is superior to that of the free–modified DSSC with the PCE of 5%. Detailed studies offer an effective approach to enhance the efficiency of dye synthesized solar cells. PMID:27143126

  16. Charge collection enhancement by incorporation of gold-silica core-shell nanoparticles into P3HT:PCBM/ZnO nanorod array hybrid solar cells.

    Wang, Ting-Chung; Su, Yen-Hsun; Hung, Yun-Kai; Yeh, Chen-Sheng; Huang, Li-Wen; Gomulya, Widianta; Lai, Lai-Hung; Loi, Maria A; Yang, Jih-Sheng; Wu, Jih-Jen

    2015-08-14

    In this work, gold-silica core-shell (Au@silica) nanoparticles (NPs) with various silica-shell thicknesses are incorporated into P3HT:PCBM/ZnO nanorod (NR) hybrid solar cells. Enhancement in the short-circuit current density and the efficiency of the hybrid solar cells is attained with the appropriate addition of Au@silica NPs regardless of the silica-shell thickness. Compared to the P3HT:PCBM/ZnO NR hybrid solar cell, a 63% enhancement in the efficiency is achieved by the P3HT:PCBM/Au@silica NP/ZnO NR hybrid solar cell. The finite difference time domain simulations indicate that the strength of the Fano resonance, i.e., the electric field of the quasi-static asymmetric quadrupole, on the surface of Au@silica NPs in the P3HT:PCBM/ZnO NR hybrid significantly decreases with increasing thickness of the silica shell. Raman characterization reveals that the degree of P3HT order increases when Au@silica NPs are incorporated into the P3HT:PCBM/ZnO NR hybrid. The charge separation at the interface between P3HT and PCBM as well as the electron transport in the active layer are retarded by the electric field of the Fano resonance. Nevertheless, the prolongation of the electron lifetime and the reduction of the electron transit time in the P3HT:PCBM/ZnO NR hybrid solar cells, which result in an enhancement of electron collection, are achieved by the addition of Au@silica NPs. This may be attributed to the improvement in the degree of P3HT order and connectivity of PCBM when Au@silica NPs are incorporated into the P3HT:PCBM active layer. PMID:26159896

  17. Nucleus accumbens dopamine receptors in the consolidation of spatial memory.

    Mele, A.; Avena, M.; Roullet, P.; Leonibus, E. de; Mandillo, S.; Sargolini, F.; Coccurello, R.; Oliverio, A.

    2004-01-01

    Nucleus accumbens dopamine is known to play an important role in motor activity and in behaviours governed by drugs and natural reinforcers, as well as in non-associative forms of learning. At the same time, activation of D1 and D2 dopamine receptors has been suggested to promote intracellular event

  18. Rapid feedback processing in human nucleus accumbens and motor thalamus

    Schüller, T.; Gründler, T.O.J.; Jocham, G.; Klein, T.A.; Timmermann, L.; Visser-Vandewalle, V.E.R.M.; Kuhn, J.

    2015-01-01

    The nucleus accumbens (NAcc) and thalamus are integral parts in models of feedback processing. Deep brain stimulation (DBS) has been successfully employed to alleviate symptoms of psychiatric conditions including obsessive-compulsive disorder (OCD) and Tourette's syndrome (TS). Common target structu

  19. Enhanced Conductivity in CZTS/Cu(2-x)Se Nanocrystal Thin Films: Growth of a Conductive Shell.

    Korala, Lasantha; McGoffin, J Tyler; Prieto, Amy L

    2016-02-01

    Poor charge transport in Cu2ZnSnS4 (CZTS) nanocrystal (NC) thin films presents a great challenge in the fabrication of solar cells without postannealing treatments. We introduce a novel approach to facilitate the charge carrier hopping between CZTS NCs by growing a stoichiometric Cu2Se shell that can be oxidized to form a conductive Cu2-xSe phase when exposed to air. The CZTS/Cu2Se core/shell NCs with varying numbers of shell monolayers were synthesized by the successive ionic layer adsorption and reaction (SILAR) method, and the variation in structural and optical properties of the CZTS NCs with varying shell thicknesses was investigated. Solid-phase sulfide ligand exchange was employed to fabricate NC thin films by layer-by-layer dip coating and a 2 orders of magnitude rise in dark conductivity (∼10(-3) S cm(-1) at 0 monolayer and ∼10(-1) S cm(-1) at 1.5 monolayers) was observed with an increase in the number of shell monolayers. The approach described herein is the first key step in achieving a significant increase in the photoconductivity of as-deposited CZTS NC thin films. PMID:26745286

  20. Zn2SnO4@C core–shell nanorods with enhanced anodic performance for lithium-ion batteries

    Highlights: • Zn2SnO4@C core–shell nanorods have been successfully fabricated. • A simple hydrothermal and subsequent carbonization approach was employed. • The carbon layer offers good buffering effect and improve electronic conductivity. • The composites demonstrate improved performance as anode for Li-ion batteries. • This performance was attributed to the core–shell structure with carbon matrix. - Abstract: Novel Zn2SnO4@C core–shell nanorods have been prepared by a simple hydrothermal and subsequent carbonization approach. A series of morphology and structural characteristics are conducted on the obtained material, including X-ray diffraction, transmission electron microscopy combined with energy-dispersive X-ray spectrometer, high-resolution transmission electron microscopy, Raman spectroscopy, and thermal gravimetric analysis, followed by electrochemical study. When evaluating as anode materials for lithium-ion batteries, the as-synthesized Zn2SnO4@C core–shell nanorods exhibit improved electrochemical properties with higher Li storage capacity and longer cycle life compared to the pristine Zn2SnO4 nanorods. The novel core–shell nano structure with excellent buffering effect and better Li storage performance provide a promising use of anode material for Li ion battery

  1. Silicon nanotube field effect transistor with core-shell gate stacks for enhanced high-performance operation and area scaling benefits

    Fahad, Hossain M.

    2011-10-12

    We introduce the concept of a silicon nanotube field effect transistor whose unique core-shell gate stacks help achieve full volume inversion by giving a surge in minority carrier concentration in the near vicinity of the ultrathin channel and at the same time rapid roll-off at the source and drain junctions constituting velocity saturation-induced higher drive current-enhanced high performance per device with efficient real estate consumption. The core-shell gate stacks also provide superior short channel effects control than classical planar metal oxide semiconductor field effect transistor (MOSFET) and gate-all-around nanowire FET. The proposed device offers the true potential to be an ideal blend for quantum ballistic transport study of device property control by bottom-up approach and high-density integration compatibility using top-down state-of-the-art complementary metal oxide semiconductor flow. © 2011 American Chemical Society.

  2. Controlled synthesis of magnetic iron oxides@SnO2 quasi-hollow core-shell heterostructures: formation mechanism, and enhanced photocatalytic activity

    Wu, Wei; Zhang, Shaofeng; Ren, Feng; Xiao, Xiangheng; Zhou, Juan; Jiang, Changzhong

    2011-11-01

    Iron oxide/SnO2 magnetic semiconductor core-shell heterostructures with high purity were synthesized by a low-cost, surfactant-free and environmentally friendly hydrothermal strategy via a seed-mediated method. The morphology and structure of the hybrid nanostructures were characterized by means of high-resolution transmission electron microscopy and X-ray diffraction. The morphology evolution investigations reveal that the Kirkendall effect directs the diffusion and causes the formation of iron oxide/SnO2 quasi-hollow particles. Significantly, the as-obtained iron oxides/SnO2 core-shell heterostructures exhibited enhanced visible light or UV photocatalytic abilities, remarkably superior to as-used α-Fe2O3 seeds and commercial SnO2 products, mainly owing to the effective electron hole separation at the iron oxides/SnO2 interfaces.Iron oxide/SnO2 magnetic semiconductor core-shell heterostructures with high purity were synthesized by a low-cost, surfactant-free and environmentally friendly hydrothermal strategy via a seed-mediated method. The morphology and structure of the hybrid nanostructures were characterized by means of high-resolution transmission electron microscopy and X-ray diffraction. The morphology evolution investigations reveal that the Kirkendall effect directs the diffusion and causes the formation of iron oxide/SnO2 quasi-hollow particles. Significantly, the as-obtained iron oxides/SnO2 core-shell heterostructures exhibited enhanced visible light or UV photocatalytic abilities, remarkably superior to as-used α-Fe2O3 seeds and commercial SnO2 products, mainly owing to the effective electron hole separation at the iron oxides/SnO2 interfaces. Electronic supplementary information (ESI) available: TEM and HRTEM images of hematite seeds and iron oxide/SnO2 (12 h and 36 h). See DOI: 10.1039/c1nr10728c

  3. Improved formulation for the stabilized enhanced strain solid-shell element (SHB8PS): geometric linear and nonlinear applications

    ABED-MERAIM, Farid; Combescure, Alain

    2007-01-01

    In this study, the formulation of the SHB8PS solid-shell element is reviewed in order to eliminate some persistent membrane and shear locking phenomena. The resulting physically stabilized and locking-free finite element consists in a continuum mechanics shell element based on a purely three-dimensional formulation. In fact, this is a hexahedral element with eight nodes as well as five integration points, all distributed along the “thickness” direction. Consequently, it can be used for the mo...

  4. Highly narrow nanogap-containing Au@Au core-shell SERS nanoparticles: size-dependent Raman enhancement and applications in cancer cell imaging

    Hu, Chongya; Shen, Jianlei; Yan, Juan; Zhong, Jian; Qin, Weiwei; Liu, Rui; Aldalbahi, Ali; Zuo, Xiaolei; Song, Shiping; Fan, Chunhai; He, Dannong

    2016-01-01

    Cellular imaging technologies employing metallic surface-enhanced Raman scattering (SERS) tags have gained much interest toward clinical diagnostics, but they are still suffering from poor controlled distribution of hot spots and reproducibility of SERS signals. Here, we report the fabrication and characterization of high narrow nanogap-containing Au@Au core-shell SERS nanoparticles (GCNPs) for the identification and imaging of proteins overexpressed on the surface of cancer cells. First, plasmonic nanostructures are made of gold nanoparticles (~15 nm) coated with gold shells, between which a highly narrow and uniform nanogap (~1.1 nm) is formed owing to polyA anchored on the Au cores. The well controlled distribution of Raman reporter molecules, such as 4,4'-dipyridyl (44DP) and 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), are readily encoded in the nanogap and can generate strong, reproducible SERS signals. In addition, we have investigated the size-dependent SERS activity of GCNPs and found that with the same laser wavelength, the Raman enhancement discriminated between particle sizes. The maximum Raman enhancement was achieved at a certain threshold of particle size (~76 nm). High narrow nanogap-containing Au@Au core-shell SERS tags (GCTs) were prepared via the functionalization of hyaluronic acid (HA) on GCNPs, which recognized the CD44 receptor, a tumor-associated surface biomarker. And it was shown that GCTs have a good targeting ability to tumour cells and promising prospects for multiplex biomarker detection.Cellular imaging technologies employing metallic surface-enhanced Raman scattering (SERS) tags have gained much interest toward clinical diagnostics, but they are still suffering from poor controlled distribution of hot spots and reproducibility of SERS signals. Here, we report the fabrication and characterization of high narrow nanogap-containing Au@Au core-shell SERS nanoparticles (GCNPs) for the identification and imaging of proteins overexpressed on

  5. Stimulated dopamine overflow and alpha-synuclein expression in the nucleus accumbens core distinguish rats bred for differential ethanol preference.

    Pelkonen, Anssi; Hiltunen, Mikko; Kiianmaa, Kalervo; Yavich, Leonid

    2010-08-01

    The key neurochemical systems and structures involved in the predisposition to substance abuse and preference to ethanol (EtOH) are not known in detail but clearly dopamine (DA) is an important modulator of addiction. Recent data indicate that alpha-synuclein (alpha-syn), a pre-synaptic protein, plays a role in regulation of DA release from the pre-synaptic terminals in striatum and the expression of this protein is different after drug abuse or following abstinence. In the present work, we analysed stimulated DA overflow in the dorsal and ventral striatum in EtOH naïve alko alchohol (AA) and alko non-alchohol (ANA) rats selected for more than 100 generations for their differential EtOH preference. In the same structures, we studied the expression of alpha-syn using western blotting. AA rats, in comparison with ANA rats, showed a marked reduction of stimulated peak DA overflow and higher levels of alpha-syn in the nucleus accumbens core. In the same structure, DA re-uptake was increased in AA rats in comparison with ANA rats. The effects of EtOH at low (0.1 g/kg) and higher (3 mg/kg) doses on DA overflow measured in the nucleus accumbens shell were similar in both lines. These results indicate that high expression of alpha-syn may contribute to the reduced DA overflow and the possible activation of re-uptake in the nucleus accumbens core of AA rats in comparison with ANA rats. PMID:20533994

  6. Tailored Rh surface facilitates, enhancement of Raman scattering in trimetallic AuPt core/Rh shell composites: Experimental and theoretical evidences

    Loganathan, B.; Chandraboss, V. L.; Senthilvelan, S.; Karthikeyan, B.

    2016-01-01

    We present a detailed analysis of surface-enhanced Raman scattering of 7-azaindole and L-cysteine adsorbed on a tailored Rh surface by using experimental and density functional theoretical (DFT) calculations. DFT with the B3LYP/Lanl2DZ basis set was used for the optimization of the ground state geometries and simulation of the surface-enhanced Raman spectrum of probe molecules adsorbed on Rh6 cluster. 7-azaindole and L-cysteine adsorption at the shell interface was ascertained from first-principles. In addition, characterization of synthesized trimetallic AuPt core/Rh shell colloidal nanocomposites has been analyzed by UV-visible spectroscopy, high-resolution transmission and scanning electron microscopy, selected area electron diffraction pattern analysis, energy-dispersive X-ray spectroscopy, atomic force, confocal Raman microscopy, FT-Raman and surface-enhanced Raman spectroscopic analysis. This analysis serves as the first step in gaining an accurate understanding of specific interactions at the interface of organic and biomolecules and to gain knowledge on the surface composition of trimetallic Au/Pt/Rh colloidal nanocomposites.

  7. Constructing a MoS₂ QDs/CdS Core/Shell Flowerlike Nanosphere Hierarchical Heterostructure for the Enhanced Stability and Photocatalytic Activity.

    Liang, Shijing; Zhou, Zhouming; Wu, Xiuqin; Zhu, Shuying; Bi, Jinhong; Zhou, Limin; Liu, Minghua; Wu, Ling

    2016-01-01

    MoS₂ quantum dots (QDs)/CdS core/shell nanospheres with a hierarchical heterostructure have been prepared by a simple microwave hydrothermal method. The as-prepared samples are characterized by XRD, TEM, SEM, UV-VIS diffuse reflectance spectra (DRS) and N₂-sorption in detail. The photocatalytic activities of the samples are evaluated by water splitting into hydrogen. Results show that the as-prepared MoS₂ QDs/CdS core/shell nanospheres with a diameter of about 300 nm are composed of the shell of CdS nanorods and the core of MoS₂ QDs. For the photocatalytic reaction, the samples exhibit a high stability of the photocatalytic activity and a much higher hydrogen evolution rate than the pure CdS, the composite prepared by a physical mixture, and the Pt-loaded CdS sample. In addition, the stability of CdS has also been greatly enhanced. The effect of the reaction time on the formations of nanospheres, the photoelectric properties and the photocatalytic activities of the samples has been investigated. Finally, a possible photocatalytic reaction process has also been proposed. PMID:26891284

  8. A Platinum Monolayer Core-Shell Catalyst with a Ternary Alloy Nanoparticle Core and Enhanced Stability for the Oxygen Reduction Reaction

    Haoxiong Nan

    2015-01-01

    Full Text Available We synthesize a platinum monolayer core-shell catalyst with a ternary alloy nanoparticle core of Pd, Ir, and Ni. A Pt monolayer is deposited on carbon-supported PdIrNi nanoparticles using an underpotential deposition method, in which a copper monolayer is applied to the ternary nanoparticles; this is followed by the galvanic displacement of Cu with Pt to generate a Pt monolayer on the surface of the core. The core-shell Pd1Ir1Ni2@Pt/C catalyst exhibits excellent oxygen reduction reaction activity, yielding a mass activity significantly higher than that of Pt monolayer catalysts containing PdIr or PdNi nanoparticles as cores and four times higher than that of a commercial Pt/C electrocatalyst. In 0.1 M HClO4, the half-wave potential reaches 0.91 V, about 30 mV higher than that of Pt/C. We verify the structure and composition of the carbon-supported PdIrNi nanoparticles using X-ray powder diffraction, X-ray photoelectron spectroscopy, thermogravimetry, transmission electron microscopy, and energy dispersive X-ray spectrometry, and we perform a stability test that confirms the excellent stability of our core-shell catalyst. We suggest that the porous structure resulting from the dissolution of Ni in the alloy nanoparticles may be the main reason for the catalyst’s enhanced performance.

  9. Constructing a MoS2 QDs/CdS Core/Shell Flowerlike Nanosphere Hierarchical Heterostructure for the Enhanced Stability and Photocatalytic Activity

    Shijing Liang

    2016-02-01

    Full Text Available MoS2 quantum dots (QDs/CdS core/shell nanospheres with a hierarchical heterostructure have been prepared by a simple microwave hydrothermal method. The as-prepared samples are characterized by XRD, TEM, SEM, UV-VIS diffuse reflectance spectra (DRS and N2-sorption in detail. The photocatalytic activities of the samples are evaluated by water splitting into hydrogen. Results show that the as-prepared MoS2 QDs/CdS core/shell nanospheres with a diameter of about 300 nm are composed of the shell of CdS nanorods and the core of MoS2 QDs. For the photocatalytic reaction, the samples exhibit a high stability of the photocatalytic activity and a much higher hydrogen evolution rate than the pure CdS, the composite prepared by a physical mixture, and the Pt-loaded CdS sample. In addition, the stability of CdS has also been greatly enhanced. The effect of the reaction time on the formations of nanospheres, the photoelectric properties and the photocatalytic activities of the samples has been investigated. Finally, a possible photocatalytic reaction process has also been proposed.

  10. Facile fabrication of novel SiO2/g-C3N4 core-shell nanosphere photocatalysts with enhanced visible light activity

    Lin, Bo; Xue, Chao; Yan, Xiaoqing; Yang, Guidong; Yang, Guang; Yang, Bolun

    2015-12-01

    Novel SiO2/g-C3N4 core-shell nanospheres were simply synthesized using heating method to anneal the mixture of silica dioxide nanospheres and molten cyanamide (CA) in nitrogen atmosphere. The effects of various initial mass ratios of SiO2 nanospheres and CA molecules on the catalyst structure, surface property and catalytic activity have been systematically investigated. The characterization results show that the as-obtained photocatalysts possess the ordered core-shell nanostructure, large mesoporous distribution and inflated BET specific surface areas. The photocatalytic activities of the SiO2/g-C3N4 composites were evaluated by decomposing the rhodamine B (RhB) dye under visible light irradiation. Compared with pure g-C3N4, all of the SiO2/g-C3N4 core-shell composites showed the improved photoactivity, and the optimal SiO2/g-C3N4 catalyst (SC-3) showed the highest activity with an RhB conversion of 94.3% after 150 min visible light irradiation, which is 3.5 times higher than that of pure g-C3N4. Meanwhile, the recycling test showed that the SC-3 sample owns outstanding stability and durability. The enhancement in both activity and stability can be assigned to the specific core-shell structure, inflated surface area, higher visible light adsorption and efficient charge separation originating from the closely contacted interfaces between SiO2 nanospheres and g-C3N4.

  11. Cu, Cu-Cu2O core-shell, and hollow Cu2O nanodendrites: Structural evolution and reverse surface-enhanced Raman scattering

    Cu-Cu2O core-shell nanodendrites and Cu2O hollow dendrites were prepared for the first time by distinct heat treatments of single crystalline Cu nanodendrites synthesized by the proposed low toxicity electrodeposition route. The crystallographic directions of the nanodendrites were studied by high resolution transmission electron microscopy and the orientation relations of Cu2O and Cu from the Cu-Cu2O core-shell nanodendrites were found to be Cu(1 1 1)[0 1-bar 1]||Cu2O(0 0 1)[1 1-bar 0]. Hollow Cu2O nanodendrites were characterized as quasi-single crystalline structures, which are proposed to form via the evaporation and escape of Cu in the core part of nanodendrites during specific heat treatments. Raman spectra show reverse surface-enhanced Raman scattering (SERS) effects for Cu and Cu-Cu2O core-shell nanodendrites in detecting absorbed 4-aminobenzenethiol molecules under 633 and 532 nm excitation. The Cu-Cu2O core-shell dendrites show an even stronger SERS effect than Cu dendrites under 532 nm excitation, which is attributed to near resonance excitations and shape effects. Contact angle measurements show the contact angles of Cu, Cu-Cu2O, and hollow Cu2O nanodendrites are 20.9o, 133.2o, and 104.9o, respectively. These diverse nanodendrites not only provide abundant directions for academic research, but are also promising for sensing, self-cleaning, electronic devices and drug delivery applications.

  12. A High-Fat Meal, or Intraperitoneal Administration of a Fat Emulsion, Increases Extracellular Dopamine in the Nucleus Accumbens

    Bartley G. Hoebel

    2012-06-01

    Full Text Available Evidence links dopamine (DA in the nucleus accumbens (NAc shell to the ingestion of palatable diets. Less is known, however, about the specific relation of DA to dietary fat and circulating triglycerides (TG, which are stimulated by fat intake and promote overeating. The present experiments tested in Sprague-Dawley rats whether extracellular levels of NAc DA increase in response to acute access to fat-rich food or peripheral injection of a fat emulsion and, if so, whether this is related to caloric intake or elevated circulating lipids. When rats consumed more calories of a high-fat meal compared with a low-fat meal, there was a significant increase in extracellular accumbens DA (155% vs. 119%. Systemic injection of a fat emulsion, which like a high-fat diet raises circulating TG but eliminates the factor of taste and allows for the control of caloric intake, also significantly increased extracellular levels of DA (127% compared to an equicaloric glucose solution (70% and saline (85%. Together, this suggests that a rise in circulating TG may contribute to the stimulatory effect of a high-fat diet on NAc DA.

  13. Natural weathering studies of oil palm trunk lumber (OPTL) green polymer composites enhanced with oil palm shell (OPS) nanoparticles

    Islam, Md Nazrul; Dungani, Rudi; Abdul Khalil, HPS; Alwani, M Siti; Nadirah, WO Wan; Fizree, H Mohammad

    2013-01-01

    In this study, a green composite was produced from Oil Palm Trunk Lumber (OPTL) by impregnating oil palm shell (OPS) nanoparticles with formaldehyde resin. The changes of physical, mechanical and morphological properties of the OPS nanoparticles impregnated OPTL as a result of natural weathering was investigated. The OPS fibres were ground with a ball-mill for producing nanoparticles before being mixed with the phenol formaldehyde (PF) resin at a concentration of 1, 3, 5 and 10% w/w basis and...

  14. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation

    Hsu, Chiajen; Huang, Chienwen; Hao, Yaowu; Liu, Fuqiang

    2013-01-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet–visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became ...

  15. Clinical experience with cytomegalovirus isolation using conventional cell cultures and early antigen detection in centrifugation-enhanced shell vial cultures.

    Leland, D S; Hansing, R L; French, M L

    1989-01-01

    A total of 1,915 clinical samples was inoculated by low-speed centrifugation into shell vials (Bartels Immunodiagnostics, Bellvue, Wash.) containing cover slip monolayers of MRC-5 fibroblasts. At 1 and 2 days postinoculation, one cover slip was stained by an indirect immunofluorescence technique using a monoclonal antibody (Biotech Research Laboratories for Dupont, Billerica, Mass.) to cytomegalovirus (CMV) early antigen (EA). Clinical samples were also inoculated into three MRC-5 or MRHF cel...

  16. Fabrication of hollow platinum-ruthenium core-shell catalysts with nanochannels and enhanced performance for methanol oxidation

    Hu, Yuming; Zhu, Aimei; Zhang, Qiugen; Liu, Qinglin

    2015-12-01

    This work reports the preparation of hollow PtRu core-shell catalysts with TiO2 as template, in which the Pt nanoparticles (NPs) grow on the exterior surface of Ru layer. The quantity of Pt NPs is easily tailored to control the integrity of Pt shell through varying the concentration of H2PtCl6 solution. Scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and selected-area electron diffraction (SAED) are used to characterize the structure and morphology of H-PtRu. The core-shell structure is confirmed by the high-angle annular dark-field scanning TEM (HAADF-STEM) with energy-disperse X-ray spectroscopy (EDX). The electrochemical performance of H-PtRu is investigated by cyclic voltammetry and chronoamperometry. Results show that the catalytic activity of H-PtRu toward methanol oxidation reaction (MOR) is ∼2.5 times higher than that of Pt/C (JM), and the electrocatalytic stability improves with the increase of Ru content. Furthermore, H-PtRu exhibits better stability for methanol oxidation compared to Pt/C (JM) and PtRu/C (JM).

  17. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation

    Hsu, Chiajen; Huang, Chienwen; Hao, Yaowu; Liu, Fuqiang

    2013-03-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm-2 at 0.3 V) than the commercial Pd black (0.85 mA cm-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies.

  18. Nucleus accumbens lesions modulate the effects of Methylphenidate

    Podet, Adam; Lee, Min J.; Swann, Alan C.; Dafny, Nachum

    2010-01-01

    The psychostimulant methylphenidate (MPD, Ritalin) is the prescribed drug of choice for treatment of ADHD. In recent years, the diagnosis rate of ADHD has increased dramatically, as have the number of MPD prescriptions. Repeated exposure to psychostimulants produces behavioral sensitization in rats, an experimental indicator of a drug’s potential liability. In studies on cocaine and amphetamine, this effect has been reported to involve the nucleus accumbens (NAc), one of the nuclei belonging ...

  19. Alterations in blood glucose levels under hyperinsulinemia affect accumbens dopamine

    Bello, Nicholas T.; Hajnal, Andras

    2006-01-01

    Dopaminergic systems have been implicated in diabetes and obesity. Notwithstanding, the most basic relationship between dopamine and plasma insulin as well as glucose levels yet remains unknown. The present experiments were designed to investigate the effects of acute hyperinsulinemia on basal dopamine levels in the nucleus accumbens of the rat under chloral hydrate anesthesia using acute microdialysis in combination with the hyperinsulinemic-glycemic clamping procedure. In Experiment 1, each...

  20. Relief memory consolidation requires protein synthesis within the nucleus accumbens.

    Bruning, Johann E A; Breitfeld, Tino; Kahl, Evelyn; Bergado-Acosta, Jorge R; Fendt, Markus

    2016-06-01

    Relief learning refers to the association of a stimulus with the relief from an aversive event. The thus-learned relief stimulus then can induce, e.g., an attenuation of the startle response or approach behavior, indicating positive valence. Previous studies revealed that the nucleus accumbens is essential for the acquisition and retrieval of relief memory. Here, we ask whether the nucleus accumbens is also the brain site for consolidation of relief memory into a long-term form. In rats, we blocked local protein synthesis within the nucleus accumbens by local infusions of anisomycin at different time points during a relief conditioning experiment. Accumbal anisomycin injections immediately after the relief conditioning session, but not 4 h later, prevented the consolidation into long-term relief memory. The retention of already consolidated relief memory was not affected by anisomycin injections. This identifies a time window and site for relief memory consolidation. These findings should complement our understanding of the full range of effects of adverse experiences, including cases of their distortion in humans such as post-traumatic stress disorder and/or phobias. PMID:26792192

  1. Activation of D2 dopamine receptor-expressing neurons in the nucleus accumbens increases motivation

    Soares-Cunha, Carina; Coimbra, Barbara; David-Pereira, Ana; Borges, Sonia; Pinto, Luisa; Costa, Patricio; Sousa, Nuno; Rodrigues, Ana J.

    2016-01-01

    Striatal dopamine receptor D1-expressing neurons have been classically associated with positive reinforcement and reward, whereas D2 neurons are associated with negative reinforcement and aversion. Here we demonstrate that the pattern of activation of D1 and D2 neurons in the nucleus accumbens (NAc) predicts motivational drive, and that optogenetic activation of either neuronal population enhances motivation in mice. Using a different approach in rats, we further show that activating NAc D2 neurons increases cue-induced motivational drive in control animals and in a model that presents anhedonia and motivational deficits; conversely, optogenetic inhibition of D2 neurons decreases motivation. Our results suggest that the classic view of D1–D2 functional antagonism does not hold true for all dimensions of reward-related behaviours, and that D2 neurons may play a more prominent pro-motivation role than originally anticipated. PMID:27337658

  2. Reacquisition of cocaine conditioned place preference and its inhibition by previous social interaction preferentially affect D1-medium spiny neurons in the accumbens corridor

    Janine Maria Prast

    2014-09-01

    Full Text Available We investigated if counterconditioning with dyadic (i.e., one-to-one social interaction, a strong inhibitor of the subsequent reacquisition of cocaine conditioned place preference (CPP, differentially modulates the activity of the diverse brain regions oriented along a mediolateral corridor reaching from the interhemispheric sulcus to the anterior commissure, i.e., the nucleus of the vertical limb of the diagonal band, the medial septal nucleus, the major island of Calleja, the intermediate part of the lateral septal nucleus, and the medial accumbens shell and core. We also investigated the involvement of the lateral accumbens core and the dorsal caudate putamen. The anterior cingulate 1 (Cg1 region served as a negative control. Contrary to our expectations, we found that all regions of the accumbens corridor showed increased expression of the early growth response protein 1 (EGR1, Zif268 in rats 2 h after reacquisition of CPP for cocaine after a history of cocaine CPP acquisition and extinction. Previous counterconditioning with dyadic social interaction inhibited both the reacquisition of cocaine CPP and the activation of the whole accumbens corridor. EGR1 activation was predominantly found in dynorphin-labeled cells, i.e., presumably D1 receptor-expressing medium spiny neurons (D1-MSNs, with D2-MSNs (immunolabeled with an anti-DRD2 antibody being less affected. Cholinergic interneurons or GABAergic interneurons positive for parvalbumin, neuropeptide Y or calretinin were not involved in these CPP-related EGR1 changes. Glial cells did not show any EGR1 expression either. The present findings could be of relevance for the therapy of impaired social interaction in substance use disorders, depression, psychosis, and autism spectrum disorders.

  3. Plasmonic enhancement of the optical absorption and catalytic efficiency of BiVO₄ photoanodes decorated with Ag@SiO₂ core-shell nanoparticles.

    Abdi, Fatwa F; Dabirian, Ali; Dam, Bernard; van de Krol, Roel

    2014-08-01

    Recent progress in the development of bismuth vanadate (BiVO4) photoanodes has firmly established it as a promising material for solar water splitting applications. Performance limitations due to intrinsically poor catalytic activity and slow electron transport have been successfully addressed through the application of water oxidation co-catalysts and novel doping strategies. The next bottleneck to tackle is the modest optical absorption in BiVO4, particularly close to its absorption edge of 2.4 eV. Here, we explore the modification of the BiVO4 surface with Ag@SiO2 core-shell plasmonic nanoparticles. A photocurrent enhancement by a factor of ~2.5 is found under 1 sun illumination (AM1.5). We show that this enhancement consists of two contributions: optical absorption and catalysis. The optical absorption enhancement is induced by the excitation of localized surface plasmon resonances in the Ag nanoparticles, and agrees well with our full-field electromagnetic simulations. Far-field effects (scattering) are found to be dominant, with a smaller contribution from near-field plasmonic enhancement. In addition, a significant catalytic enhancement is observed, which is tentatively attributed to the electrocatalytic activity of the Ag@SiO2 nanoparticles. PMID:24942363

  4. Serotonergic antidepressants decrease hedonic signals but leave learning signals in the nucleus accumbens unaffected.

    Graf, Heiko; Metzger, Coraline D; Walter, Martin; Abler, Birgit

    2016-01-01

    Investigating the effects of serotonergic antidepressants on neural correlates of visual erotic stimulation revealed decreased reactivity within the dopaminergic reward network along with decreased subjective sexual functioning compared with placebo. However, a global dampening of the reward system under serotonergic drugs is not intuitive considering clinical observations of their beneficial effects in the treatment of depression. Particularly, learning signals as coded in prediction error processing within the dopaminergic reward system can be assumed to be rather enhanced as antidepressant drugs have been demonstrated to facilitate the efficacy of psychotherapeutic interventions relying on learning processes. Within the same study sample, we now explored the effects of serotonergic and dopaminergic/noradrenergic antidepressants on prediction error signals compared with placebo by functional MRI. A total of 17 healthy male participants (mean age: 25.4 years) were investigated under the administration of paroxetine, bupropion and placebo for 7 days each within a randomized, double-blind, within-subject cross-over design. During functional MRI, we used an established monetary incentive task to explore neural prediction error signals within the bilateral nucleus accumbens as region of interest within the dopaminergic reward system. In contrast to diminished neural activations and subjective sexual functioning under the serotonergic agent paroxetine under visual erotic stimulation, we revealed unaffected or even enhanced neural prediction error processing within the nucleus accumbens under this antidepressant along with unaffected behavioural processing. Our study provides evidence that serotonergic antidepressants facilitate prediction error signalling and may support suggestions of beneficial effects of these agents on reinforced learning as an essential element in behavioural psychotherapy. PMID:26555033

  5. Enhanced removal performance by the core-shell zeolites/MgFe-layered double hydroxides (LDHs) for municipal wastewater treatment.

    Guo, Lu; Zhang, Xiangling; Chen, Qiaozhen; Ruan, Congying; Leng, Yujie

    2016-04-01

    The application of powdered layer double hydroxides (LDHs) in constructed rapid infiltration system (CRIS) appears to be an appreciable problem still unsolved due to the small particle size and the low density. Therefore, the core-shell zeolites/MgFe-LDHs composites were prepared via using co-precipitation method in present study. To investigate the practical applicability, a detailed organics, ammonia, and total phosphorus removal study were carried out in columns to treat the municipal wastewater. The scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) results confirmed the successful synthesis of core-shell zeolites/MgFe-LDHs through coating on the surface of zeolites. Accordingly, the zeolites/MgFe-LDHs largely reduced the COD by 81.14 %, NH4 (+)-N by 81.50%, and TP by 83.29%. Phosphate adsorption study revealed that the equilibrium adsorption data were better fitted by Langmuir isothermal model, with the maximum adsorption capacity of 79.3651 mg/kg for zeolites/MgFe-LDHs and 38.4615 mg/kg for the natural zeolites. In addition, economic analysis indicated that the reagent cost of synthesis of zeolites/MgFe-LDHs was economical. Herein, the zeolites/MgFe-LDHs solved the natural zeolites problem for poor P removal and the application of powdered LDHs in the solid/liquid separation process, suggesting that it was applicable as potential substrates for the removal of organics, ammonia, and total phosphorus in CRIS. PMID:26662562

  6. Multicomponent (Ce, Cu, Ni) oxides with cage and core-shell structures: tunable fabrication and enhanced CO oxidation activity

    Liu, Wei; Tang, Ke; Lin, Ming; June, Lay Ting Ong; Bai, Shi-Qiang; Young, David James; Li, Xu; Yang, Yan-Zhao; Hor, T. S. Andy

    2016-05-01

    Solvothermal synthesis of Cu2O cubes from Cu(OAc)2 in ethanol provided templates for tunable formation of novel multicomponent composites: hollow CeO2-Cu2O (1), core-shell NiO@Cu2O (2) and hollow CeO2-NiO-Cu2O (3). Composites 1-3 catalyze the oxidation of CO at a lower temperature than the parent Cu2O cubes.Solvothermal synthesis of Cu2O cubes from Cu(OAc)2 in ethanol provided templates for tunable formation of novel multicomponent composites: hollow CeO2-Cu2O (1), core-shell NiO@Cu2O (2) and hollow CeO2-NiO-Cu2O (3). Composites 1-3 catalyze the oxidation of CO at a lower temperature than the parent Cu2O cubes. Electronic supplementary information (ESI) available: Experimental section: materials and characterization; synthesis of materials; catalytic test. Tables S1-S3 and Fig. S1-S8. See DOI: 10.1039/c6nr02383e

  7. Enhancing photoresponsivity of ultra violet photodetectors based on Fe doped ZnO/ZnO shell/core nanorods

    Highlights: • Fe doped ZnO/ZnO nanorods by hydrothermal followed by dip coating method was reported. • Fe ions incorporated in Fe3+ state considerably influenced the physical properties. • The nanorods resistance notably reduced with Fe concentration of ZnO shell layer. • Photoresponsivity of Fe doped ZnO nanorods as a detectors increased with Fe doping. - Abstract: In this work, the structural, electrical and optical properties of pure and Fe doped ZnO/ZnO shell/core nanorods samples with different Fe concentrations (0–9 at.%) were studied. The samples were prepared using a two-step method; hydrothermal followed by dip coating for encapsulation process. The X-ray diffraction (XRD) results showed the Fe doping improved the crystallinity of ZnO nanorods at an optimized value (4.5 at.%). The encapsulation increased nanorods diameter by magnitude ∼20–40 nm. The structural and optical properties evidenced the Fe ions substituted with valence state 3+ into Zn2+ sites. The I–V measurements showed that resistance was increased with increase in Fe-doping due to increase carrier concentration confirmed existence of Fe ions in valance state 3+. The photoresponsivity of UV photodetectors based Fe doped ZnO nanorods demonstrated an increase trend with Fe doping

  8. Enhancement of Performance of Shell and Tube Heat Exchanger Using Pertinent Leakage Flow Between Baffle and Tube Bundles

    Hap, Nguyen Van; Lee, Geun Sik [Ulsan University, Ulsan (Korea, Republic of)

    2015-03-15

    In this study, the effects of the leakage flow between the baffle and tube bundles on the performance of a shell and tube heat exchanger (STHE) were examined using the commercial software ANSYS FLUENT v.14. A computational fluid dynamics model was developed for a small STHE with five different cases for the ratio of the leakage cross-sectional area to the baffle cross-sectional area, ranging from 0 to 40%, in order to determine the optimum leakage flow corresponding to the maximum outlet temperature. Using fixed tube wall and inlet temperatures for the shell side of the STHE, the flow and temperature fields were calculated by increasing the Reynolds number from 4952 to 14858. The present results showed that the outlet temperature, pressure drop, and heat transfer coefficient were strongly affected by the leakage flow, as well as the Reynolds number. In contrast with a previous researchers finding that the leakage flow led to simultaneous decreases in the pressure drop and heat transfer rate, the present study found that the pertinent leakage flow provided momentum in the recirculation zone near the baffle plate and thus led to the maximum outlet temperature, a small pressure drop, and the highest heat transfer rate. The optimum leakage flow was shown in the case with a ratio of 20% among the five different cases.

  9. Enhancement of Performance of Shell and Tube Heat Exchanger Using Pertinent Leakage Flow Between Baffle and Tube Bundles

    In this study, the effects of the leakage flow between the baffle and tube bundles on the performance of a shell and tube heat exchanger (STHE) were examined using the commercial software ANSYS FLUENT v.14. A computational fluid dynamics model was developed for a small STHE with five different cases for the ratio of the leakage cross-sectional area to the baffle cross-sectional area, ranging from 0 to 40%, in order to determine the optimum leakage flow corresponding to the maximum outlet temperature. Using fixed tube wall and inlet temperatures for the shell side of the STHE, the flow and temperature fields were calculated by increasing the Reynolds number from 4952 to 14858. The present results showed that the outlet temperature, pressure drop, and heat transfer coefficient were strongly affected by the leakage flow, as well as the Reynolds number. In contrast with a previous researchers finding that the leakage flow led to simultaneous decreases in the pressure drop and heat transfer rate, the present study found that the pertinent leakage flow provided momentum in the recirculation zone near the baffle plate and thus led to the maximum outlet temperature, a small pressure drop, and the highest heat transfer rate. The optimum leakage flow was shown in the case with a ratio of 20% among the five different cases.

  10. Stimulation of adenosine receptors in the nucleus accumbens reverses the expression of cocaine sensitization and cross-sensitization to dopamine D2 receptors in rats

    Hobson, Benjamin D.; Merritt, Kathryn E.; Bachtell, Ryan K.

    2012-01-01

    Adenosine receptors co-localize with dopamine receptors on medium spiny nucleus accumbens (NAc) neurons where they antagonize dopamine receptor activity. It remains unclear whether adenosine receptor stimulation in the NAc restores cocaine-induced enhancements in dopamine receptor sensitivity. The goal of these studies was to determine whether stimulating A1 or A2A receptors in the NAc reduces the expression of cocaine sensitization. Rats were sensitized with 7 daily treatments of cocaine (15...