Browsing by Author "Zhang, Bin"
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- Crystallin Mu in Medial Amygdala Mediates the Effect of Social Experience on Cocaine Seeking in Males but Not in FemalesWalker, Deena M.; Zhou, Xianxiao; Cunningham, Ashley M.; Ramakrishnan, Aarthi; Cates, Hannah M.; Lardner, Casey K.; Pena, Catherine J.; Bagot, Rosemary C.; Issler, Orna; van der Zee, Yentl; Lipschultz, Andrew P.; Godino, Arthur; Browne, Caleb J.; Hodes, Georgia E.; Parise, Eric M.; Torres-Berrio, Angelica; Kennedy, Pamela J.; Shen, Li; Zhang, Bin; Nestler, Eric J. (Elsevier, 2022-06-30)Background: Social experiences influence susceptibility to substance use disorder. The adolescent period is associated with the development of social reward and is exceptionally sensitive to disruptions to reward-associated behaviors by social experiences. Social isolation (SI) during adolescence alters anxiety- and reward-related behaviors in adult males, but little is known about females. The medial amygdala (meA) is a likely candidate for the modulation of social influence on drug reward because it regulates social reward, develops during adolescence, and is sensitive to social stress. However, little is known regarding how the meA responds to drugs of abuse. Methods: We used adolescent SI coupled with RNA sequencing to better understand the molecular mechanisms underlying meA regulation of social influence on reward. Results: We show that SI in adolescence, a well-established preclinical model for addiction susceptibility, enhances preference for cocaine in male but not in female mice and alters cocaine-induced protein and transcriptional profiles within the adult meA particularly in males. To determine whether transcriptional mechanisms within the meA are important for these behavioral effects, we manipulated Crym expression, a sex-specific key driver gene identified through differential gene expression and coexpression network analyses, specifically in meA neurons. Overexpression of Crym, but not another key driver that did not meet our sex-specific criteria, recapitulated the behavioral and transcriptional effects of adolescent SI. Conclusions: These results show that the meA is essential for modulating the sex-specific effects of social experience on drug reward and establish Crym as a critical mediator of sex-specific behavioral and transcriptional plasticity.
- Development of the Advanced Emitter Turn-Off (ETO) ThyristorZhang, Bin (Virginia Tech, 2005-01-21)Advancements in the power electronics systems have been directly related to the availability of improved power semiconductor devices. The device performance greatly determines the efficiency, reliability, volume, and cost of the power electronics system. This dissertation is dedicated to develop an advanced high power semiconductor device, the emitter turn-off (ETO) thyristor, which is targeted to improve the limitations of the present high power devices. Major improvements in electrical and mechanical designs of the ETO for high power and high frequency operation are proposed which result in improved snubberless turn-off capability, low conduction loss, and low gate drive power consumption of the new generation ETO. A revolutionary self-power generation method of the ETO is proposed. Different from the conventional high power devices which require the external power input for their gate drivers, ETO achieves complete optically controlled turn-on and turn-off and all the internal power required is self-generated. This advancement will have a major impact to high power converter designs. A novel integrated method to eliminate the dead-time requirement is proposed for ETO. This method not only improves the output waveform quality but also increases the reliability and reduces the cost of the high power PWM voltage source converters. With this unique function, the upper and the lower ETO's within a converter phase leg can receive the ideal complementary (without dead-time) PWM signals and solve shoot-through problems. Method to measure the ETO current and transfer the current information to a PWM signal is proposed. Based on the ETO's built-in current sensor, the over-current protection function of the ETO is designed as well. The experimental results show that the built-in current sensor has a very high precision, and the over-current protection function can effectively protect the ETO during the short circuit faults. In order to improve ETO's turn-off capability, a comprehensive investigation of the turn-off failure mechanism of the ETO was performed. A series of simulations and experiments are carried out to study the ETO turn-off operation. The detail turn-off failure mechanisms are presented. The conditions to cause the ETO failure are addressed. The approaches to improve the ETO's turn-off capability are discussed.
- Emitter turn-off thyristors and their drive circuits(United States Patent and Trademark Office, 2004-03-23)A family of emitter turn-off thyristors and their drive circuit comprise a gate turn-on (GTO) thyristor, a first switch, the drain of the first switch being connected to the cathode of the GTO thyristor, and a second switch connected between the gate of the GTO thyristor and the source of the first switch. The first switch consists of many paralleled metal oxide semiconductor field effect transistors (MOSFETs). The anode of the GTO thyristor and the source of the first switch serve as the annode and the cathode, respective, of the emitter turn-off thyristor. The emitter turn-off thyristor has four control electrodes: the gate of the GTO thyristor, the control electrode of the second switch, the gate of the first switch, and the cathode of the GTO thyristor. The drive circuit comprises a current source circuit, a voltage clamp circuit, a current direction detector, and a control circuit. The ETO thyristor further comprises a current sensing and over-current detector circuit. The first switch is packaged in a printed circuit board.
- Synthesis and Characterization of trans-1,4-Cyclohexylene Ring Containing Poly(arylene ether sulfone)sZhang, Bin (Virginia Tech, 2012-01-13)Poly(arylene ether sulfone)s (PAES) are important commercial polymers and have been extensively studied due to their excellent thermal and mechanical properties. However, some applications are still limited when good solvent resistance and low thermal expansion coefficient are required. There has been a continuous interest in developing new PAES based on new monomers or polymer modifications to obtain new properties or to enhance existing properties. In this dissertation, the synthesis, characterization and structure-property relationship of new 1,4-cyclohexylene ring containing PAESs were comprehensively studied. Different polymerization techniques were used to synthesize polymers with different segmental lengths. The monomer, 4,4'-[trans-1,4-cyclohexanebis(methylene)] bisphenol (CMB), was synthesized and fully characterized. Based on 4,4′-dihydroxy-p-terphenyl (DHTP), 4,4′-dihydroxybiphenyl (DHBP) and the CMB monomer, homopolymer and random copolymers of PAES were prepared with high molecular weights and high glass transition temperatures. Dynamic mechanical analysis (DMA) on these polymers showed multiple sub-Tg relaxations. A large increase in the ultimate elongation was obtained with the CMB and DHTP containing sample, which could be due to the strong sub-Tg relaxations observed from the DMA results. A series of four acid chloride monomers were synthesized and polymerized with phenol terminated PAES oligomers. Solution polymerization and pseudo-interfacial polymerization techniques were used to prepare both bisphenol-A (bis-A) based and DHBP based PAES oligomers. With the incorporation of the trans-1,4-cyclohexylene units, decreases in the glass transition temperatures were observed from both the bis-A based and the DHBP based polymers. However, melting transitions were only observed in the DHBP based trans-1,4-cyclohexylene containing PAESs. Crystallinity was confirmed by differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD). A mechanical property study of the high molecular weight trans-1,4-cyclohexylene containing polymer samples showed moderate ultimate elongation enhancements. A series of PAES-polyester multiblock copolymers were synthesized with both solution method and melt polymerization. In the solution method, phenol terminated PAES oligomers and the acid chloride terminated poly(1,4-cyclohexylenedimethylene terephthalate) (PCT) oligomers were presynthesized and coupled in solution. The molecular weights of the polymer products obtained from the solution method were limited by solubility issues. Melt phase polymerization was employed to obtain high molecular weight polymers. Hydroxy ethoxy terminated PAES oligomers were synthesized and polymerized with 1,4-cyclohexanedimethanol (CHDM) and dimethyl terephthalate (DMT) in the melt. Polymers with high molecular weights were obtained. Tensile test results suggested that the mechanical properties of these polymers were dominated by the PAES components with polyester contents up to 20 wt%. Melting transitions were observed from polymers with higher polyester contents, and these polymers exhibited limited solubility in common organic solvents.