Investigating the Influence of GABA Neurons on Dopamine Neurons in the Ventral Tegmental Area Using Optogenetic Techniques

Dopamine (DA) is the key regulator of reward behavior. The DA neurons in the ventral tegmental area (VTA) and their projection areas, which include the prefrontal cortex (PFC), nucleus accumbens (NAc), and amygdala, play a primary role in the process of reward-driven behavior induced by the drugs of addiction, including nicotine and alcohol. In our previous study, we developed a novel platform consisting of micro-LED array devices to stimulate a large area of the brain of rats and monkeys with photo-stimulation and a microdialysis probe to estimate the DA release in the PFC. Our results suggested that the platform was able to detect the increased level of dopamine in the PFC in response to the photo-stimulation of both the PFC and VTA. In this study, we used this platform to photo-stimulate the VTA neurons in both ChrimsonR-expressing (non-specific) wild and dopamine transporter (DAT)-Cre (dopamine specific) mice, and measured the dopamine release in the nucleus accumbens shell (NAcShell). We measured the DA release in the NAcShell in response to optogenetic stimulation of the VTA neurons and investigated the effect of GABAergic neurons on dopaminergic neurons by histochemical studies. Comparing the photo-stimulation frequency of 2 Hz with that of 20 Hz, the change in DA concentration at the NAcShell was greater at 20 Hz in both cases. When ChrimsonR was expressed specifically for DA, the release of DA at the NAcShell increased in response to photo-stimulation of the VTA. In contrast, when ChrimsonR was expressed non-specifically, the amount of DA released was almost unchanged upon photo-stimulation. However, for nonspecifically expressed ChrimsonR, intraperitoneal injection of bicuculline, a competitive antagonist at the GABA-binding site of the GABA_A receptor, also significantly increased the release of DA at the NAcShell in response to photo-stimulation of the VTA. The results of immunochemical staining confirm that GABAergic neurons in the VTA suppress DA activation, and also indicate that alterations in GABAergic neurons may have serious downstream effects on DA activity, NAcShell release, and neural adaptation of the VTA. This study also confirms that optogenetics technology is crucial to study the relationship between the mesolimbic dopaminergic and GABAergic neurons in a neural-specific manner.     

Thermal management and power saving operations for improved energy efficiency within a renewable hydrogen energy system utilizing metal hydride hydrogen storage

To ensure the energy efficiency of renewable hydrogen energy systems, power conservation and thermal management are necessary. This study applies these principals to the operation of metal hydride tanks (MHTs) in a bench-scale hydrogen system, named Hydro Q-BiC?, comprising photovoltaic panels (20 kW), an electrolyzer (5 Nm³/h), MHTs containing a TiFe-based MH (40 Nm³), fuel cells (FC; 3.5 kW(power)/2.5 kW(heat)), and Li-ion batteries (20 kW/20 kWh). Here, we show that in a modified hydrogen production operation, with limited use of auxiliaries for cooling the MHTs, the power consumption of the MHTs was reduced by more than 99% compared to a typical operation. The thermal requirements for the MHTs were reduced by ceasing production in a pressurized state. During the hydrogen use operation, the power consumption was reduced to 1/4 and the FC heat output could be fully used; hence, the overall energy efficiency (power-to-hydrogen-to-power/heat) was as high as ~ 60% (43% for the typical operation).     

Estimation of consequence and damage caused by an organic hydride hydrogen refueling station

Organic hydride hydrogen refueling stations are currently being developed in Japan. For these stations, we estimate the consequence and damage caused by explosions and heat radiation after a hydrogen leak, and the acute toxicity caused by the leakage and dispersion of methylcyclohexane and toluene energy carriers. First, the organic hydride hydrogen refueling station is defined, and an accident scenario for four leak sizes of hydrogen and chemical leak accidents is set. Next, simulations of the blast wave pressure and heat radiation after the hydrogen leak and of atmospheric dispersion for the evaporation after liquid methylcyclohexane and toluene leaks are performed. Probit functions or threshold values are created for each type of effects caused by the explosion, heat and the inhalation effect on humans of toluene acute toxicity. Population data for the area surrounding the station are created in a 10-m mesh. The consequence and damage are estimated for each leak size. The results show that although the explosion and chemical leak affects the area around the refueling station, the effects are small in all of the accident scenarios. In contrast, although the area of the heat effect is limited to inside the refueling station, the burn damage is large, and there is a need for conducting quantitative risk assessment.     

Seismic analysis of nuclear power plants by using three-dimensional finite element models: a review

ABSTRACT

Seismic design of nuclear power plants (NPPs) is important for ensuring their integrity during earthquakes. Seismic analysis has been conducted using lumped mass beam models (LMBMs) for the design of plants in Japan, whereas three-dimensional (3D) finite element models (FEMs) have been used for novel plants outside Japan. The purposes of this study are to organize issues related to the development and application of 3D FEMs for seismic analysis of Japanese NPPs and to indicate future study directions. To organize these issues, the authors systematically investigated: (1) international guides and standards related to seismic analysis and (2) 3D FEMs of novel NPPs outside Japan. By considering other studies on the issues, the authors suggest directions for future studies. Resolving the issues will contribute to application of 3D FEMs for seismic analysis in the design of Japanese NPPs.     

Mixing Phase Behavior of 1,3-Dipalmitoyl-2-Oleoyl-sn-Glycerol (POP) and 1,2-Dipalmitoyl-3-Oleoyl-rac-Glycerol (PPO) in n-Dodecane Solution

We examined the mixing phase behavior of 1,3-dipalmitoyl-2-oleoyl-sn-glycerol (POP) and 1,2-dipalmitoyl-3-oleoyl-rac-glycerol (PPO) in organic solutions containing n-dodecane (C₁₂) as a solvent to confirm whether the molecular compound (MC) crystals of POP/PPO are formed as metastable and most stable forms in the dilute solution by using DSC and synchrotron radiation X-ray diffraction. The POP/PPO mixtures were prepared at different concentration ratios of POP and PPO with a 10 % increment in two solutions having weight concentration ratios of (POP+PPO):C₁₂ of 50:50 (50 % solution) and 20:80 (20 % solution). We found that MC crystals formed at a ratio of POP/PPO = 50/50 having the melting point of 23.1 and 20.6 °C in 50 and 20 % solution systems in stable states of incubated samples, respectively. The metastable (β′) and stable (β) forms of MC of POP/PPO = 50/50 having a double-chain-length structure were confirmed in kinetic behavior and thermodynamically stable states attained after long time incubation, in contrast to the triple-chain-length structure of stable forms of POP (β) and PPO (β′). In addition, we observed the formation of MC crystals of POP/PPO in diluted solutions having n-dodecane concentrations up to 98 % and conclude that molecular interactions between POP and PPO molecules to form MC crystals are not altered by solvent molecules in diluted solutions.     

Formal Nucleophilic Boryl Substitution of Organic Halides with Silylborane/Alkoxy Base System

Boryl substitution of organohalides with a silylborane and alkoxy bases is described. This reaction can be applied to various functionalized aryl halides. Alkyl and alkenyl halides, and even sterically congested aryl bromides also provided the corresponding borylated products in high yields. Mechanistic studies indicated that neither trace transition-metal impurities nor aryl radical species involved in this reaction.     

Nanomodification of Glass Using fs Laser

We review the interaction of glass with intense ultrashort laser pulses revealing new phenomena and recent demonstrations of rewritable 5D optical memory and polarization imaging filter mediated by the self-organization of nanostructure. Particularly, we experimentally verify linearly polarized intense ultrashort pulses can control the direction of local optical anisotropy in homogeneous medium based on the interference between photon and electron plasma. These so-called “nanogratings” composed of the photoinduced oxygen defects emerge in the course of multiple laser pulses and are oriented perpendicularly to the laser polarization direction. The nanograting structures, which exhibit form birefringence, have evolved from residual birefringence along with lowering threshold for defect formation into self-assembly of oxygen defects.     

A critical condition for the formation of a coarse columnar γ grain structure in a peritectic solidified carbon steel

The formation of a coarse columnar austenite grain (CCG) structure is a serious problem in continuous casting processes of peritectic solidified carbon steels. In this study, a guiding principle for the avoidance of CCG formation is developed. The critical condition for CCG formation recently put forward based on phase-field simulations, which is given by a balance between the cooling condition and the growth rate of the CCG, is first re-examined and modified by considering the effect of a liquid phase during the CCG formation. The validity of this critical condition is then investigated by three different casting experiments combined with heat conduction analyses. From a comparison between the cooling conditions and the resulting microstructural changes, the validity of the critical condition is successfully demonstrated.