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O-GlcNAcylation is a posttranslational modification that adds O-linked β-N-acetylglucosamine (O-GlcNAc) to serine or threonine residues of many proteins. This protein modification interacts with key cellular pathways involved in transcription, translation, and proteostasis. Although ubiquitous throughout the body, O-GlcNAc is particularly abundant in the brain, and various proteins commonly found at synapses are O-GlcNAcylated. Recent studies have demonstrated that the modulation of O-GlcNAc in the brain alters synaptic and neuronal functions. Furthermore, altered brain O-GlcNAcylation is associated with either the etiology or pathology of numerous neurodegenerative diseases, while the manipulation of O-GlcNAc exerts neuroprotective effects against these diseases. Although the detailed molecular mechanisms underlying the functional roles of O-GlcNAcylation in the brain remain unclear, O-GlcNAcylation is critical for regulating diverse neural functions, and its levels change during normal and pathological aging. In this review, we will highlight the functional importance of O-GlcNAcylation in the brain and neurodegenerative diseases., Neurodegeneration: Sugar tags on proteins linked to brain disease The addition of a sugar tag called O-GlcNAc to proteins found in brain cells plays a critical role in regulating synaptic and neuronal function, with implications for understanding and treating neurodegenerative disease. Jae-Ick Kim and colleagues, Ulsan National Institute of Science and Technology, South Korea, review the ways in which the attachment or removal of O-GlcNAc sugars to or from proteins in the central nervous system can impact neuronal survival and the functional properties of neural circuits. In the aging brain, O-GlcNAc levels often become dysregulated, leading to aberrant protein activity that can fuel cognitive decline. In various neurodegenerative disorders such as Alzheimer’s, Parkinson’s, and Huntington’s diseases, and amyotrophic lateral sclerosis, relevant disease-associated proteins often have abnormal O-GlcNAc patterns. Therapeutically altering the sugar-tagging process could potentially offer a new way of treating these brain disorders.

Dopaminergic axons originate in the midbrain and establish widely spread synapses throughout the brain. Synaptic transmission at these synapses plays a crucial role for volitional movement and reward-related behaviors, while dysfunction of dopamine (DA) synapses causes various psychiatric and neurological disorders. Despite this significance, the true nature of brain-wide spatial and functional features of DA synapses remains poorly understood due to difficulties defining functional DA synapses at the molecular and physiological levels. Here we show that DA synapses are structured and function like GABAergic synapses in the mouse brain with marked regional heterogeneity. DA transmission is strongly correlated with GABA co-transmission at DA synapses across the brain areas. In addition, functional DA synapses possess GABAergic postsynaptic markers and are unevenly distributed throughout the brain with distinct spatial clustering. In the dorsal striatum, GABAergic-like DA synapses are uniquely clustered on the dendrites and GABA transmission at DA synapses has disparate physiological properties. Remarkably, the attenuation of GABA co-transmission precedes deficits in dopaminergic transmission in animal model of Parkinsonism. Our findings unravel distinct spatial and functional nature of GABAergic-like DA synapses in health and disease. Furthermore, the broader implication of our results is that GABAergic-like features of DA synapses can be utilized to better understand the real complexity of synaptic actions at DA synapses in regulating neural circuits.

Generation of autologous human motor neurons holds great promise for cell replacement therapy to treat spinal cord injury (SCI). Direct conversion allows generation of target cells from somatic cells, however, current protocols are not practicable for therapeutic purposes since converted cells are post-mitotic that are not scalable. Therefore, therapeutic effects of directly converted neurons have not been elucidated yet. Here, we show that human fibroblasts can be converted into induced motor neurons (iMNs) by sequentially inducing POU5F1(OCT4) and LHX3. Our strategy enables scalable production of pure iMNs because of the transient acquisition of proliferative iMN-intermediate cell stage which is distinct from neural progenitors. iMNs exhibited hallmarks of spinal motor neurons including transcriptional profiles, electrophysiological property, synaptic activity, and neuromuscular junction formation. Remarkably, transplantation of iMNs showed therapeutic effects, promoting locomotor functional recovery in rodent SCI model. Together, our advanced strategy will provide tools to acquire sufficient human iMNs that may represent a promising cell source for personalized cell therapy.

A supersonic dual coaxial jet has been employed popularly for various industrial purposes, such as gasdynamic laser, supersonic ejector, noise control and enhancement of mixing. Detailed characteristics of supersonic dual coaxial jets issuing from an inner supersonic nozzle and outer sonic nozzles with various ejection angles are experimentally investigated. Three important parameters, such as pressure ratios of the inner and outer nozzles, and outer nozzle ejection angle, are chosen for a better understanding of jet structures in the present study. The results obtained from the present experimental study show that the Mach disk diameter becomes smaller, and the Mach disk moves toward the nozzle exit, and the length of the first shock cell decreases with the pressure ratio of the outer nozzle. It was also found that the highly underexpanded outer jet produces a new oblique shock wave, which makes jet structure much more complicated. On the other hand the outer jet ejection angle affects the structure of the inner jet structure less than the pressure ratio of the outer nozzle, relatively.

In order to investigate the flows with shock wave in branch, 108 elbow and T-junction of the IRWST system of standard Korean nuclear reactor, detail time dependent behaviors of unsteady flow with shock wave, vortex and so on are obtained by numerical method using compressible three-dimensional Navier-Stokes equations. At first, the complex flow including the incident and reflected shock waves, vortex and expansion waves which are generated at the corner of T-junction is calculated by the commercial code of FLUENT6 and is compared with the experimental result to obtain the validation of numerical method. Then the flow fields in above mentioned units are analyzed by numerical method of [mite volume method. In numerical analysis, the distributions of flow properties with the moving of shock wave and the forces acting on the wall of each unit which can be used to calculate the size of supporting structure in future are calculated specially. It is found that the initial shock wave of normal type is re-established its type from an oblique one having the same strength of the initial shock wave at the 4 times hydraulic diameters of downstream from the branch point of each unit. Finally, it is turned out that the maximum force acting on the pipe wall becomes in order of the T-junction, 108 elbow and branch in magnitude, respectively.

Water droplet erosion is one of major concerns in the design of modern large fossil steam turbines because it causes serious operational problems such as performance degradation and reduction of service life. A new erosion model has been developed in the present study for the prediction of water droplet erosion of rotor blades operated in wet steam conditions. The major four erosion parameter ; impact velocity, impacting droplet flow rate, droplet size and hardness of target are involved in the model so that it can also be used for engineering purpose at the design stage of rotor blades. Comparison of the predicted erosion rate with the measured data obtained from the practical steam turbine operated for more than 90.000 hours shows good agreement.

Fouling deposits due to surface-coated particles have been calculated using computational fluid dynamics techniques. The sticking probabilities of the surface-coated particles are also evaluated on the basis of an energy balance. The sticking probabilities of the deposit surface are also included in the prediction of the deposition occurring through the multiple impaction of particles with the deposit surface. The sticking probability of an impacting particle is expressed in terms of such parameters as particle viscosity, surface tension, impact velocity, impact angle and the thickness of the sticky layer on a particle. Particulate behavior around a tube in cross-flow was studied using the Lagrangian approach. Three important parameters, i.e. impact velocity, impact angle, and particulate concentration, were used in the prediction of deposition rate. The computational predictions were found to be in good agreement with the experimental data.

Fouling deposits due to surface-coated particles have been calculated using CFD techniques. The sticking probabilities of the surface-coated particles are also evaluated on the basis of an energy balance. The sticking probabilities of the deposit surface are also included in the prediction of the deposition occurring through the multiple impaction of particles with the deposit surface. The sticking probability of an impacting particle is expressed in terms of such parameters as particle viscosity, surface tension, impact velocity, impact angle and the thickness of the sticky layer on a particle. Particulate behavior around a tube in cross flow was studied using the Lagrangian approach. Three important parameters i.e. impact velocity, impact angle, and particulate concentration, were used in the prediction of deposition rate. The computational predictions were found to be in good agreement with the experimental data.

Erosion of boiler tubes causes serious problems in many pulverized coal-fired utility boilers. The Eulerian approach was employed to predict the behaviour of the particulate phase. Traditionally, the Eulerian approach shows deficiencies when used in the numerical prediction of erosion, because of a lack of an appropriate wall boundary condition for the particulate phase. Comparison of the numerical prediction for a single tube erosion with experimental data shows very good agreement.