• The Korean Journal of Physiology and Pharmacology
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• v.23 no.5
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• pp.317-328
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• 2019

It is known that top-down associative inputs terminate on distal apical dendrites in layer 1 while bottom-up sensory inputs terminate on perisomatic dendrites of layer 2/3 pyramidal neurons (L2/3 PyNs) in primary sensory cortex. Since studies on synaptic transmission in layer 1 are sparse, we investigated the basic properties and cholinergic modulation of synaptic transmission in layer 1 and compared them to those in perisomatic dendrites of L2/3 PyNs of rat primary visual cortex. Using extracellular stimulations of layer 1 and layer 4, we evoked excitatory postsynaptic current/potential in synapses in distal apical dendrites (L1-EPSC/L1-EPSP) and those in perisomatic dendrites (L4-EPSC/L4-EPSP), respectively. Kinetics of L1-EPSC was slower than that of L4-EPSC. L1-EPSC showed presynaptic depression while L4-EPSC was facilitating. In contrast, inhibitory postsynaptic currents showed similar paired-pulse ratio between layer 1 and layer 4 stimulations with depression only at 100 Hz. Cholinergic stimulation induced presynaptic depression by activating muscarinic receptors in excitatory and inhibitory synapses to similar extents in both inputs. However, nicotinic stimulation enhanced excitatory synaptic transmission by ~20% in L4-EPSC. Rectification index of AMPA receptors and AMPA/NMDA ratio were similar between synapses in distal apical and perisomatic dendrites. These results provide basic properties and cholinergic modulation of synaptic transmission between distal apical and perisomatic dendrites in L2/3 PyNs of the visual cortex, which might be important for controlling information processing balance depending on attentional state.

• Journal of the Korean institute of surface engineering
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• v.51 no.5
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• pp.263-270
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• 2018

Ag-coated Cu dendrites were prepared as a filler for an electromagnetic interference shielding application. Ag layers on the Cu dendrites was coated by two approaches. One is a direct autocatalytic plating with a reducing agent. The other approach was achieved by two-step plating, a galvanic displacement reaction to form Ag seed layers on Cu following by an autocatalytic plating with a reducing agent. The procedure-dependent average particle size and tap density of Ag-coated Cu dendrites were characterized. The electrical resistance and electromagnetic interference shielding effect (EMI SE) were analyzed with the Ag-coated Cu dendrites prepared in the two approaches. Additionally, the content of the Ag coated on Cu dendrites was controlled from 2% to 20%. The electrical resistance and EMI SE were critically determined by Ag contents coated on Cu.

• Proceedings of the Korean Society of Life Science Conference
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• 2008.10a
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• pp.61.2-61.2
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• 2008

• Molecules and Cells
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• v.25 no.4
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• pp.538-544
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• 2008

Activity-dependent local translation in the dendrites of brain neurons plays an important role in the synapse-specific provision of proteins necessary for strengthening synaptic connections. In this study we carried out combined fluorescence in situ hybridization (FISH) and immunocytochemistry (IC) and showed that more than half of the eukaryotic elongation factor 1A (eEF1A) mRNA clusters overlapped with or were immediately adjacent to clusters of PSD-95, a postsynaptic marker, in the dendrites of cultured rat hippocampal neurons. Treatment of the neurons with KCl increased the density of the dendritic eEF1A mRNA clusters more than two-fold. FISH combined with IC revealed that the KCl treatment increased the density of eEF1A mRNA clusters that overlapped with or were immediately adjacent to PSD-95 clusters. These results indicate that KCl treatment increases both the density of eEF1A mRNA clusters and their synaptic association in dendrites of cultured neurons.

• Journal of Korea Foundry Society
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• v.16 no.6
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• pp.513-522
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• 1996

In the present work, we have investigated the strain-induced melt activation (SIMA) process in Al-8%Si and Al-25%Si alloys. Primary dendrites were transformed into spherical microstrctures by mushy zone heat treatments of the cold-worked alloys. Various processing parameters which govern the sphering of the dendrites have been examined. The result showed that semi-solid alloys having a typically nondendritic spherical microstructure can be easily produced by this method.

• BMB Reports
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• v.50 no.1
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• pp.5-11
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• 2017

One of the characteristics of the neurons that distinguishes them from other cells is their complex and polarized structure consisting of dendrites, cell body, and axon. The complexity and diversity of dendrites are particularly well recognized, and accumulating evidences suggest that the alterations in the dendrite structure are associated with many neurodegenerative diseases. Given the importance of the proper dendritic structures for neuronal functions, the dendrite pathology appears to have crucial contribution to the pathogenesis of neurodegenerative diseases. Nonetheless, the cellular and molecular basis of dendritic changes in the neurodegenerative diseases remains largely elusive. Previous studies in normal condition have revealed that several cellular components, such as local cytoskeletal structures and organelles located locally in dendrites, play crucial roles in dendrite growth. By reviewing what has been unveiled to date regarding dendrite growth in terms of these local cellular components, we aim to provide an insight to categorize the potential cellular basis that can be applied to the dendrite pathology manifested in many neurodegenerative diseases.

• Food Science and Biotechnology
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• v.18 no.2
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• pp.330-335
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• 2009

The principal objective of this study was to investigate changes in ice dendrite size during the freezing of tuna, in order to formulate a mathematical model of ice dendrite size. The tuna was frozen via a uni-directional heat transfer. Thermogram analysis allowed us to determine the position of the freezing front versus time, which is referred to as the freezing front rate. The morphology of the ice dendrites was assessed via scanning electron microscopy after freeze-drying, and the retained pore size was measured as ice dendrites. We noted that the mean size of ice dendrites increased with the distance to the cooling plate; however, it decreased with reductions in the cooling rate and the cooling temperature. In addition, shorter durations of the freeze-drying process decreased the freezing front rate, resulting in a larger size of the ice dendrite pores that operate as water vapor sublimation channels. According to our results, we could derive a linear regression as an empirical mathematical model equation between the ice dendrite size and the inverse of the freezing front rate.

• Journal of Korea Foundry Society
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• v.35 no.6
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• pp.178-184
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• 2015

Due to excellent abrasion resistance the high-chrome white irons are widely used in mining and mineral industries. Minor variation of carbon content in 28% chrome white iron resulted in difference in primarily solidified microstructure. Sub-eutectic (hypoeutectic) composition led to formation of primarily solidified dendrites. Formation of primarily solidified dendrites which were supersaturated with carbon and chrome also caused precipitation of fine secondary carbides that are different from relatively large plate type $M_7C_3$ carbides in the eutectic structure. Small portion of primarily solidified dendrite expected to contribute significantly to the improvement of abrasion resistance of the white iron because the dendrites provided mechanical support to carbides. The relative fraction of primary dendrite increased with reduction of carbon content from the eutectic composition. The increased fraction of primary dendrite increased hardness value of the white irons.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.4
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• pp.549-562
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• 2020

Deionized water, methanol, and ethanol were investigated for their effectiveness at dissolving LiCl-KCl-UCl3 at 25, 35, and 50℃ using inductively coupled plasma mass spectrometry (ICP-MS) to study the concentration evolution of uranium and mass ratio evolutions of lithium and potassium in these solvents. A visualization experiment of the dissolution of the ternary salt in solvents was performed at 25℃ for 2 min to gain further understanding of the reactions. Aforementioned solvents were evaluated for their performance on removing the adhered ternary salt from uranium dendrites that were electrochemically separated in a molten LiCl-KCl-UCl3 electrolyte (500℃) using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). Findings indicate that deionized water is best suited for dissolving the ternary salt and removing adhered salt from electrodeposits. The maximum uranium concentrations detected in deionized water, methanol, and ethanol for the different temperature conditions were 8.33, 5.67, 2.79 μg·L-1 for 25℃, 10.62, 5.73, 2.50 μg·L-1 for 35℃, and 11.55, 6.75, and 4.73 μg·L-1 for 50℃. ICP-MS analysis indicates that ethanol did not take up any KCl during dissolutions investigated. SEM-EDS analysis of ethanol washed uranium dendrites confirmed that KCl was still adhered to the surface. Saturation criteria is also proposed and utilized to approximate the state of saturation of the solvents used in the dissolution trials.

• Korean Journal of Metals and Materials
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• v.49 no.2
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• pp.128-136
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• 2011

Equal channel angular pressing (ECAP) with intermediate heat treatment was employed to optimize the strength of Cu-15 wt.%Ag. Changes in microstructure, electrical properties and mechanical properties were studied as a function of pressing methods and heat treatment. ECAPed Cu-15wt.%Ag exhibited ultrafine-grained microstructures with the shape and distribution of Ag-rich lamellae dependent on the processing routes. For route A in which the sample was pressed without rotation between each pass, the initial dendrites of Ag-rich phase were elongated along the shear direction and developed into elongated filaments. For route C in which the sample was rotated by 180 degree after each pass, the morphology of initial dendrites of Ag-rich phase was not much modified and the networked structure remained even after 8 passes of ECAP. For route Bc in which the sample was rotated by 90 degree after each pass, the initial dendrites became finer by fragmentation with no pronounced change of the shape and distribution of Ag-rich lamellae. The strength of Cu-15wt.%Ag ECAPed using route Bc was found to be greater than those ECAPed using route A, suggesting that the substructural strengthening is more effective in strengthening than the interface strengthening.