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ABSTRACT: This paper is mainly on the particle tracking function of MIS (Mesh Free Micro Injection Simulation Code) to explore complex flow behavior. One of the mesh free methods, SPH, has been modified in MIS to simulate the course of micro injection molding. Mass points in various positions have been monitored to help understand melt flow behaviors. According to monitored tracks, mass points follow complex wave style routines. The findings of this study have provided some fundamental supports in understanding the fountain flow behavior in micro injection molding. The influence factors of fountain flow and the phenomenon caused by it will be further researched in future study.
Computer Engineering and Technology (ICCET), 2010 2nd International Conference on; 05/2010
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ABSTRACT: The Nanxiong Basin (Guangdong Province, China) preserves the most complete Asian stratigraphic record of the Cretaceous-Paleogene (K/Pg) boundary extinction and the subsequent Paleocene mammalian radiation. Despite ex-tensive study, the precise placement of the K/Pg boundary in the Nanxiong Basin sequence has been controversial, and the timing of subsequent mammalian turnover is poorly constrained. We present new paleomagnetic and geo-chemical data from the Late Cretaceous Pingling Formation (Nanxiong Group) and the overlying Paleocene Shanghu, Nongshan, and Guchengcun formations (Luofozhai Group). Our samples are directly correlated with previous geo-chemical and paleontological sampling localities, allowing for easy comparison with other local proxy records. Results indicate that the traditional placement of the K/Pg boundary at the base of a chaotic channel sandstone bed marking the highest stratigraphic appearance of dinosaur eggshell fragments and lowest stratigraphic appearance of Paleocene mammalian fossils lies about two-thirds of the way up Chron C29R, consistent with the placement of the boundary in all other well-documented sections. The average carbon isotope composition of paleosol carbonates decreases by 12‰ in the Early Paleocene, consistent with a major disruption to global carbon cycling after the K/Pg boundary. Constraints on the age of the first major Cenozoic mammalian turnover event in Asia (the Shanghuan-Nongshanian Asian Land Mammal Age boundary) support its placement near the top of Chron C27N, which coincides with a similar turnover in North America and geochemical changes recorded in several deep sea cores.
The Journal of Geology. 01/2010; 118:131-143.
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ABSTRACT: Sink mark is one of the flaws occurring on the surface of injection-molded parts caused by inappropriate mold design and process parameters. Sink marks are often quite visible and significantly impair the surface quality of the parts. In this reports, an L27(313) experimental matrix designed based on the Taguchi method was conducted to investigate the effect of process parameters and two-way interactions on sink mark depth of injection molded parts, and to minimize the sink mark depth. The relative significance of each processing parameter on the sink marks was analyzed using analysis of variance (ANOVA) and F-test. A plate cavity with bosses of various thicknesses was used in the investigation. Experiments were carried out on a CJ80E II injection-molding machine, and sink mark depths were measured by a movable bridge 3D COMERO. For the factors and interactions selected in the main experiments, the boss thickness and melt temperature were found to be the principal factors affecting sink mark formation in injection-molded parts. Experimental investigation can help to understand the formation mechanism of sink marks, and to optimize the surface quality of injection-olded parts.
Polymer-Plastics Technology and Engineering 01/2008; 47(1):30-35. · 1.28 Impact Factor
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ABSTRACT: The gastrin precursor peptide, progastrin (PG), is secreted from enteroendocrine cells in the intestine and increased in patients with hypergastrinemia and colorectal cancers. In recent years, we and others have demonstrated an important role of PG peptides in colorectal carcinogenesis, and were surprised to note significant changes in the behaviors of transgenic mice overexpressing PGs. In the present studies, we examined emotional behaviors of transgenic mice overexpressing PG in the intestinal and peripheral circulation. Aggression, locomotor activity and anxiety-like behaviors of the homozygous transgenic (Tg/Tg) mice and the wild-type (WT) littermates were examined by intruder/resident test, open field and elevated plus maze, respectively. A significant increase in the aggression, locomotor activity, and anxiety-like behaviors was detected in the Tg/Tg vs WT mice. As CCK, CCK(2) receptors (CCK(2)R), and 5-HT(1A) receptors (5-HT(1A)R) in the CNS play an important role in these behaviors, possible changes in the expression of CCK and CCK(2)R and the density of CCK(2)R and 5-HT(1A)R were determined by either real-time RT-PCR or autoradiography of ligand binding assays. The results suggest that the expressions of CCK and CCK(2)R were increased in the hypothalamus, and the density of CCK(2)R were increased in the hypothalamus and amygdala of Tg/Tg vs WT mice. Similarly, the density of 5-HT(1A)R was increased in the hypothalamus. Our results suggest that an upregulation of the CCK response system and 5-HT(1A)R in the hypothalamus of Tg/Tg mice may mediate the alterations in the observed behaviors of these mice.
Neuropsychopharmacology 09/2007; 32(8):1813-21. · 7.99 Impact Factor
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ABSTRACT: Our previous studies found that serotonin transporter (SERT) knock-out mice showed increased sensitivity to minor stress and increased anxiety-like behavior but reduced locomotor activity. These mice also showed decreased density of 5-hydroxytryptamine (5-HT1A) receptors in the hypothalamus, amygdala, and dorsal raphe. To evaluate the contribution of hypothalamic 5-HT1A receptors to these phenotypes of SERT knock-out mice, two studies were conducted. Recombinant adenoviruses containing 5-HT1A sense and antisense sequences (Ad-1AP-sense and Ad-1AP-antisense) were used to manipulate 5-HT1A receptors in the hypothalamus. The expression of the 5-HT1A genes is controlled by the 5-HT1A promoter, so that they are only expressed in 5-HT1A receptor-containing cells. (1) Injection of Ad-1AP-sense into the hypothalamus of SERT knock-out mice restored 5-HT1A receptors in the medial hypothalamus; this effect was accompanied by elimination of the exaggerated adrenocorticotropin responses to a saline injection (minor stress) and reduced locomotor activity but not by a change in increased exploratory anxiety-like behavior. (2) To further confirm the observation in SERT-/- mice, Ad-1AP-antisense was injected into the hypothalamus of normal mice. The density and the function of 5-HT1A receptors in the medial hypothalamus were significantly reduced in Ad-1AP-antisense-treated mice. Compared with the control group (injected with Ad-track), Ad-1A-antisense-treated mice showed a significant reduction in locomotor activity, but again no changes in exploratory anxiety-like behaviors, tested by elevated plus-maze and open-field tests. Thus, the present results demonstrate that medial hypothalamic 5-HT1A receptors regulate stress responses and locomotor activity but may not regulate exploratory anxiety-like behaviors.
Journal of Neuroscience 01/2005; 24(48):10868-77. · 7.11 Impact Factor
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ABSTRACT: The expression and function of the serotonin transporter (SERT) is important in the regulation of mood and emotion. Determination of SERT alterations in physiological and pathological states is essential for understanding the role of SERT in mood regulation, and in the etiology and therapy of psychiatric disorders. Two SERT ligands, AFM ([(3)H]2-[2-(dimethylaminomethylphenylthio)]-5-fluoromethylphenylamine) and DASB ([(3)H]3-amino-4-[2-(dimethylaminomethylphenylthio)]benzonitrile), have recently been developed for positron emission tomography (PET) imaging. The aim of the present study was to determine the selectivity of these compounds for SERT. Autoradiography of AFM or DASB binding was compared in the brains of mice with genetically normal, diminished, or absent SERT. In addition, the pharmacodynamic profile of [(3)H]AFM was examined in the mouse brain. The distribution of [(3)H]AFM and [(3)H]DASB binding in the normal brains was consistent with that of previously studied serotonin reuptake inhibitors. Both ligands had negligible binding in the brain of SERT knockout mice, and binding was reduced approximately 50% in heterozygote SERT mice. The K(d) of [(3)H]AFM binding in the cortex and midbrain was 1.6 and 1.0 nM, respectively. Competition studies showed that [(3)H]AFM has very low affinity for norepinephrine and dopamine transporters as well as 5-HT receptors, including 5-HT(1A), 5-HT(1B), 5-HT(2A), and 5-HT(2C) receptors. In addition, fenfluramine showed a low capability to compete with [(3)H]AFM. The present results suggest that both AFM and DASB are highly selective SERT ligands potentially suitable for use in human PET studies of SERT.
Journal of Pharmacology and Experimental Therapeutics 03/2004; 308(2):481-6. · 3.83 Impact Factor
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ABSTRACT: The aim of the present studies was to determine the effects of reduced or absent serotonin (5-HT) transporters (5-HTTs) on 5-HT2A and 5-HT2C receptors. The density of 5-HT2C receptors was significantly increased in the amygdala and choroid plexus of 5-HTT knockout mice. On the other hand, the density of 5-HT2A receptors was significantly increased in the hypothalamus and septum, but reduced in the striatum, of 5-HTT knockout mice. However, 5-HT2A mRNA was not changed in any brain region measured. 5-HT2C mRNA was significantly reduced in the choroid plexus and lateral habenula nucleus of these mice. The function of 5-HT2A receptors was evaluated by hormonal responses to (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI). Oxytocin, but not adrenocorticotrophic hormone or corticosterone, responses to DOI were significantly greater in 5-HTT knockout mice. In addition, Gq and G11 proteins were not significantly changed in any brain region measured. The present results suggest that the constitutive alteration in the function of 5-HTTs changes the density of 5-HT2A and 5-HT2C receptors in a brain region-specific manner. These changes may not be mediated by alterations in their gene expression or in the level of Gq/11 proteins. The alterations in these receptors may be related to the altered behaviors of 5-HTT knockout mice.
Journal of Neurochemistry 04/2003; 84(6):1256-65. · 4.06 Impact Factor
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ABSTRACT: Drugs that, directly or indirectly produce activation of serotonin (5-HT) receptors increase plasma concentrations of both prolactin and renin. The serotonergic regulation of prolactin and renin secretion share several common characteristics. Serotonergic neurons originating in the dorsal raphe and terminating in the hypothalamus stimulate the secretion of both prolactin and renin. Destruction of cells in the hypothalamic paraventricular nucleus (PVN) inhibits both the prolactin and renin responses to 5-HT agonists and 5-HT-releasing drugs. Activation of 5-HT2 receptors increases the secretion of both prolactin and renin, while activation of other 5-HT receptor subtypes has differential effects on these hormones. However, there are also differences between the serotonergic mechanisms that regulate the secretion of prolactin and renin. Activation of 5-HT1A receptors increases the secretion of prolactin but not of renin. In addition, activation of peripheral 5-HT2 receptors stimulates the secretion of renin, while activation of peripheral 5-HT3 receptors increases plasma levels of prolactin but not renin. In humans, the effect of 5-HT-releasing drugs and 5-HT agonist on plasma prolactin concentrations has been studied to a greater extent than effects on most other hormones. In contrast, the renin responses to 5-HT agonists and 5-HT releasers has not been well characterized in humans. Because of the important role of the renin-angiotensin system in cardiovascular regulation, studies on the serotonergic regulation of renin release in humans could increase our understanding of cardiovascular disorders associated with altered serotonergic function. Examples include anxiety and consequences of cocaine abuse. In conclusion, comparing the serotonergic regulation of prolactin and renin secretion indicates similarities that might shed light on common brain mechanisms that regulate neuroendocrine function.
Behavioural Brain Research.
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ABSTRACT: VAN DE KAR, L. D., A. D. LEVY, Q. LI AND M. S. BROWNFIELD. A comparison of the oxytocin and vasopressin responses to the 5-HT1Aagonist and potential anxiolytic drug alnespirone (S-20499). PHARMACOL BIOCHEM BEHAV 60(3) 677–683, 1998.—The effect of the serotonin1A (5-HT1A) agonist alnespirone (S-20499) on the secretion of both oxytocin and vasopressin was examined in the same conscious, unrestrained male rats. The dose–response and time–course effects on the secretion of oxytocin and vasopressin revealed that alnespirone stimulated oxytocin in a dose-dependent manner, but did not increase vasopressin secretion. Time of maximal effect following injection of alnespirone (5 mg/kg, IP) was as early as 15 min postinjection, with significant stimulation persisting for 30 min. Pretreatment with a low dose of the 5-HT1A/β-adrenoceptor antagonist (−)-pindolol (0.3 mg/kg, SC), 30 min prior to injection of alnespirone (0, 2, 5, and 10 mg/kg, IP) shifted the dose–response curve to the right and inhibited the effect of alnespirone on plasma oxytocin concentration. Furthermore, pretreatment with a low or a high dose of the 5-HT1A/2A/dopamine D2 antagonist spiperone (0.01 or 3 mg/kg, SC) dose dependently shifted the alnespirone dose–response curve effect of alnespirone to the right. None of these drugs, alone or in combination, altered plasma vasopressin levels. These studies suggest that 5-HT1A receptor mechanisms mediate the effect of alnespirone on the secretion of oxytocin. Furthermore, these studies suggest that 5-HT1A receptor mechanisms do not participate in the serotonergic regulation of vasopressin secretion.
Pharmacology Biochemistry and Behavior.
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ABSTRACT: New paleomagnetic and isotopic results from a ∼ 1000 meter thick Paleocene stratigraphic section in the Chijiang Basin of China's Jiangxi Province provide chronostratigraphic constraints on the Shanghuan–Nongshanian Asian Land Mammal Age boundary and allow for a more accurate determination of an early Paleogene paleomagnetic pole for the South China Block. Paleomagnetic analysis of 121 sites (326 samples) reveals that the Shanghuan–Nongshanian boundary lies close to a normal-to-reverse polarity change. Stable carbon isotope analysis of dispersed organic matter and paleosol carbonates indicate a secular increase of ∼ 1.5‰ superimposed on higher frequency variations. Correlation of this magnetochemostratigraphic pattern to the global timescale suggests that the polarity reversal near the Shanghuan–Nongshanian boundary likely represents the Chron C27n–C26r transition. The Torrejonian–Tiffanian North American Land Mammal Age boundary is closely correlated to this same polarity transition, indicating nearly synchronous global mammalian turnover at this time. Because both Land Mammal Age boundaries are thought to record turnover of mostly endemic taxa, it is unlikely that the synchroneity of faunal change is due to intercontinental dispersal as documented for other early Paleogene faunal transitions (e.g. Paleocene–Eocene boundary). Instead, these mammalian faunal transitions may represent independent ecological or evolutionary responses to environmental changes that have been interpreted from marine records at this time (e.g. “Top Chron 27n Event”).These new paleomagnetic results from the Chijiang Basin are also used to augment other published data and to calculate a Paleocene paleomagnetic pole for the South China Block. The new pole shows no significant vertical axis rotation compared to the Paleocene reference pole for Eurasia indicating that much of the clockwise rotation that has been documented for the South China Block from Cretaceous deposits cannot be the result of extrusion tectonics associated with the early Paleogene India–Asia collision. Observed Cretaceous rotations of the South China Block may be the result of late Cretaceous–early Paleocene rifting in the backarc of the Kula–Pacific subduction zone.
Earth and Planetary Science Letters.
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ABSTRACT: Injection molding is the most widely used process in manufacturing plastic products. Since the quality of injection molded plastic parts are mostly influenced by process conditions, how to determine the optimum process conditions becomes the key to improving the part quality. In this paper, a combining artificial neural network and genetic algorithm (ANN/GA) method is proposed to optimize the injection molding process. In this method, a BP neural network model is developed to map the complex non-linear relationship between process conditions and quality indexes of the injection molded parts, and a GA is used in the process conditions optimization with the fitness function based on an ANN model. The combining ANN/GA method is used in the process optimization for an industrial part in order to improve the quality index of the volumetric shrinkage variation in the part. The results show that the combining ANN/GA method is an effective tool for the process optimization of injection molding.
Journal of Materials Processing Technology.
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ABSTRACT: The objective of this work was to compare the hydriding kinetics of Mg2Ni with that of Mg1.9Al0.1Ni and study the influence of the initial hydrogen pressure on the hydriding kinetics in the two-phase (α–β) region of the Mg2−xAlxNi (x=0,0.1) alloys. Experiments were carefully performed under the initial hydrogen pressure ranging from 0.275 to and isothermal condition. The obtained hydrogen absorption kinetic curves were fitted using various rate equations to reveal the mechanism of the hydriding process. It was found that the three-dimensional diffusion process dominated the hydrogen absorption. The experimental investigation suggested that increase of the initial hydrogen pressure resulted in an acceleration of hydriding transformed fraction and the kinetic characteristics of Mg2Ni alloy was improved by substituting Al for Mg due to difference in hydride structure, particle size.
International Journal of Hydrogen Energy.
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ABSTRACT: Alterations in serotonergic function following repeated cocaine injections were examined using neuroendocrine responses to a serotonin (5-HT) releaser and 5-HT agonists.Forty-two hours following administration of cocaine (1–15 mg/kg i.p.) twice daily for 7 or 30 days, male Sprague-Dawley rats were injected with the 5-HT releaser p-chloroamphetamine (PCA; 8 mg/kg i.p.) and blood samples were collected 1 h later for radioimmunoassays of plasma prolactin, plasma renin activity (PRA) and plasma renin concentration (PRC). PCA significantly increased secretion of prolactin and renin. These responses were attenuated in rats pretreated with cocaine for 30 days. In rats receiving cocaine for 7 days, the attenuation of PCA-induced secretion of prolactin and renin was less consistently observed. To determine whether these alterations were due to pre- or postsynaptic effects, rats were injected with cocaine (15 mg/kg i.p.) twice daily for 7 days, and the neuroendocrine responses to the direct 5-HT agonists RU 24969 and m-CPP were examined, 42 h after the last cocaine injection. Pretreatment with cocaine potentiated RU 24969-induced stimulation of plasma prolactin concentration. However, cocaine did not alter the ability of m-CPP to increase plasma prolactin concentrations. The stimulation of renin secretion in response to both 5-HT agonists was not altered by cocaine pretreatment. The data suggest that repeated cocaine impairs the function of serotonergic nerve terminals that regulate these endocrine responses. Furthermore, the 5-HT receptors that mediate prolactin secretion may exhibit supersensitivity.
Brain Research.
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ABSTRACT: Acute cocaine reduces renin secretion. To determine whether serotonergic neurons mediate this effect, male Sprague-Dawley rats received the serotonin (5-HT) neurotoxin 5,7-dihydroxytryptamine (75 Ωg/side, ICV) 2 weeks prior to cocaine injections (3.75–15 mg/kg, IP. 5-HT lesions attenuated the cocaine-induced reduction of plasma renin concentration (PRC), suggesting a partial 5-HT role. To determine which receptors mediate this response, rats were pretreated with the partial 5-HT1A agonist 8-[2-[4-(2-methoxyphenyl)-l-piperazinyl]ethyl]-8-azaspirol-[4,5]-decane-7,9- dione (BMY 7378) (1 mg/kg, SC), the 5-HT1C/5-HT2 antagonist ritanserin (0.1 mg/kg, SC), or the α2/5-HT1A antagonist yohimbine (1 mg/kg, SC) prior to cocaine. None of the antagonists altered the cocaine-induced suppression of PRC, although BMY 7378 and yohimbine elevated PRC. The data suggest that cocaine's effect is partially mediated by a serotonergic mechanism, but do not support a role for 5-HT1A receptors, 5-HT2/5-HT1C receptors, or α2-adrenoceptors in mediating the suppressive effect of cocaine on renin secretion.
Pharmacology Biochemistry and Behavior.
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ABSTRACT: Cocaine-induced enhancement of motor activity and extracellular dopamine concentrations exhibits sensitization upon repeated exposure. In this study, the neuroendocrine responses to cocaine were examined following cocaine pretreatment regimens which have been shown to produce behavioral sensitization. Adult male rats were injected with cocaine (15 mg/kg, IP) once daily for 14 days, followed by a dose-response challenge with cocaine (1–15 mg/kg, IP) either 18 hours or 7 days after the final pretreatment injection. Blood was collected 15 minutes following injections for radioimmunoassay of ACTH, corticosterone, prolactin, and renin. Cocaine increased plasma ACTH and corticosterone, while it decreased prolactin and renin concentrations. Pretreatment with cocaine for 2 weeks did not alter any of these endocrine responses after either the 18 hour or 7 day interval between pretreatment and challenge injections. In contrast, sensitization to the locomotor stimulant effects of cocaine was observed on the final day of pretreatment injections, and 7 days later. These data suggest that these endocrine effects of cocaine do not exhibit sensitization following repeated cocaine exposure.
Life Sciences.
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ABSTRACT: Endocrine responses to the serotonin (5-HT) 5-HTic(-/5-HT2 agonist (±)-l-(2,5-dimcthoxy-4-iodophenyl)-2-aminopropane (DOI) were utilised to evaluate cocaine-induced alterations in postsynaptic 5-HT receptor function. Rats received cocaine HC1 (0, 5 or 15 mg/kg i.p.) twice daily for 7 days. Effects of DOI (0, 0.5, 2 or 10 mg/kg i.p.) on plasma adrenocorticotropic hormone (ACTH), corticosterone, prolactin, oxytocin and renin concentrations were assessed 42 h after the final cocaine injection. DOI dose dcpcndcntly increased the plasma concentrations of each hormone. Cocaine potentiated the DOI-induced elevations of plasma ACTH, corticostcrone and prolactin concentrations. In contrast, the oxytocin response was reduced, and the renin response was unaltered by cocaine exposure. The data suggest that 5-HT2 receptor-mediated responses for ACTH, corticosterone and prolactin secretion become superscnsitivc following repeated cocaine. In contrast, the 5-HT2, receptor-mediated response for oxytocin secretion is subscnsitive. The cocaine-induced changes in posisynaptic 5-HT receptor function are likely a consequence of deficits in the function of 5-HT nerve terminals, that we have documented previously.
European Journal of Pharmacology.
