WC-Co is used widely in die and mold industries due to its unique combination of hardness, strength and wear-resistance. For machining difficult-to-cut materials, such as tungsten carbide, micro-electrical discharge m...WC-Co is used widely in die and mold industries due to its unique combination of hardness, strength and wear-resistance. For machining difficult-to-cut materials, such as tungsten carbide, micro-electrical discharge machining(EDM) is one of the most effective methods for making holes because the hardness is not a dominant parameter in EDM. This paper describes the characteristics of the discharge conditions for micro-hole EDM of tungsten carbide with a WC grain size of 0.5 μm and Co content of 12%. The EDM process was conducted by varying the condenser and resistance values. A R-C discharge EDM device using arc erosion for micro-hole machining was suggested. Furthermore, the characteristics of the developed micro-EDM were analyzed in terms of the electro-optical observation using an oscilloscope and field emission scanning electron microscope.展开更多
We have previously found that long-term effects of exposure to radiofrequency electromagnetic fields in 5xFAD mice with severe late-stage Alzheimer’s disease reduced both amyloid-βdeposition and glial activation,inc...We have previously found that long-term effects of exposure to radiofrequency electromagnetic fields in 5xFAD mice with severe late-stage Alzheimer’s disease reduced both amyloid-βdeposition and glial activation,including microglia.To examine whether this therapeutic effect is due to the regulation of activated microglia,we analyzed mic roglial gene expression profiles and the existence of microglia in the brain in this study.5xFAD mice at the age of 1.5 months were assigned to sham-and radiofrequency electromagnetic fields-exposed groups and then animals were exposed to 1950 MHz radiofrequency electromagnetic fields at a specific absorption rate of 5 W/kg for 2 hours/day and 5 days/week for 6 months.We conducted behavioral tests including the object recognition and Y-maze tests and molecular and histopathological analysis of amyloid precursor protein/a myloid-beta metabolism in brain tissue.We confirmed that radiofrequency electromagnetic field exposure for 6 months ameliorated cognitive impairment and amyloid-βdeposition.The expression levels of Iba1(pan-microglial marker)and colony-stimulating factor 1 receptor(CSF1R;regulates microglial prolife ration)in the hippocampus in 5xFAD mice treated with radiofrequency electromagnetic fields were significantly reduced compared with those of the sham-exposed group.Subsequently,we analyzed the expression levels of genes related to mic rogliosis and microglial function in the radiofrequency electromagnetic fields-exposed group compared to those of a CSF1R inhibitor(PLX3397)-treated group.Both radiofrequency electromagnetic fields and PLX3397 suppressed the levels of genes related to microgliosis(Csf1r,CD68,and Ccl6)and pro-inflammatory cytokine interleukin-1β.N otably,the expression levels of genes related to mic roglial function,including Trem2,Fcgr1α,Ctss,and Spi1,were decreased after long-term radiofrequency electromagnetic field exposure,which was also observed in response to microglial suppression by PLX3397.These results showed that radiofrequency electromagnetic fields ameliorated amyloid-βpathology and cognitive impairment by suppressing amyloid-βdeposition-induced microgliosis and their key regulator,CSF1R.展开更多
Hypoglycemia is a frequent and potentially severe complication that can result in significant brain injury in individuals with diabetes treated with insulin or other hypoglycemic agents and in those undergoing prolong...Hypoglycemia is a frequent and potentially severe complication that can result in significant brain injury in individuals with diabetes treated with insulin or other hypoglycemic agents and in those undergoing prolonged fasting.Despite its clinical importance,the molecular mechanisms through which hypoglycemia induces neurodegeneration remain poorly defined.We therefore investigated the molecular and cellular basis of hypoglycemia-induced brain damage using human neuron and glial cell cultures in vitro and hypoglycemic mouse models in vivo.We found that starvation-induced hypoglycemia triggers hallmark neurodegenerative features,such as astrocyte activation and microglial reactivity,that closely resemble those found in the brains of hypoglycemic mouse models.Neurons notably activate an adaptive survival response mediated by serum response factor(SRF)and myocardin-related transcription factor-A(MRTF-A),which drives a metabolic reprogramming process.This shift enables neurons to use extracellular matrix components as alternative energy sources under glucose deprivation.However,this compensatory mechanism results in the excessive accumulation of urea cycle byproducts,which subsequently exacerbates neuronal damage and promotes glial activation.Glucose refeeding remarkably reversed these neurodegenerative features by deactivating SRF/MRTF-A signaling in both in vitro and in vivo.Collectively,our results revealed a neuron-intrinsic mechanism linking glucose deprivation to reversible neurodegeneration via SRF/MRTF-A,offering potential targets for preventing hypoglycemia-associated brain damage.展开更多
Dear Editor,Lung cancer is the most common cause of cancer-related mortality worldwide,with non-small cell lung cancer(NSCLC)accounting for the largest number of cases.1 Ionizing radiation(IR)is widely used as an indi...Dear Editor,Lung cancer is the most common cause of cancer-related mortality worldwide,with non-small cell lung cancer(NSCLC)accounting for the largest number of cases.1 Ionizing radiation(IR)is widely used as an indispensable tool for treating lung cancer patients;however,the acquisition of resistance following radiation is the major obstacle for reducing the efficacy of radiotherapy.展开更多
基金supported by a Grant-in-aid for the National Core Research Center Program from MOST and KOSEF, Korea (No.R15-2006-022-01001-0)partly supported by Pusan National University Research Grand,2008
文摘WC-Co is used widely in die and mold industries due to its unique combination of hardness, strength and wear-resistance. For machining difficult-to-cut materials, such as tungsten carbide, micro-electrical discharge machining(EDM) is one of the most effective methods for making holes because the hardness is not a dominant parameter in EDM. This paper describes the characteristics of the discharge conditions for micro-hole EDM of tungsten carbide with a WC grain size of 0.5 μm and Co content of 12%. The EDM process was conducted by varying the condenser and resistance values. A R-C discharge EDM device using arc erosion for micro-hole machining was suggested. Furthermore, the characteristics of the developed micro-EDM were analyzed in terms of the electro-optical observation using an oscilloscope and field emission scanning electron microscope.
基金Institute of Information&Communications Technology Planning&Evaluation(IITP)grant funded by Korea government(MSIT),Nos.2017-0-00961 and 2019-0-00102(to HDC)。
文摘We have previously found that long-term effects of exposure to radiofrequency electromagnetic fields in 5xFAD mice with severe late-stage Alzheimer’s disease reduced both amyloid-βdeposition and glial activation,including microglia.To examine whether this therapeutic effect is due to the regulation of activated microglia,we analyzed mic roglial gene expression profiles and the existence of microglia in the brain in this study.5xFAD mice at the age of 1.5 months were assigned to sham-and radiofrequency electromagnetic fields-exposed groups and then animals were exposed to 1950 MHz radiofrequency electromagnetic fields at a specific absorption rate of 5 W/kg for 2 hours/day and 5 days/week for 6 months.We conducted behavioral tests including the object recognition and Y-maze tests and molecular and histopathological analysis of amyloid precursor protein/a myloid-beta metabolism in brain tissue.We confirmed that radiofrequency electromagnetic field exposure for 6 months ameliorated cognitive impairment and amyloid-βdeposition.The expression levels of Iba1(pan-microglial marker)and colony-stimulating factor 1 receptor(CSF1R;regulates microglial prolife ration)in the hippocampus in 5xFAD mice treated with radiofrequency electromagnetic fields were significantly reduced compared with those of the sham-exposed group.Subsequently,we analyzed the expression levels of genes related to mic rogliosis and microglial function in the radiofrequency electromagnetic fields-exposed group compared to those of a CSF1R inhibitor(PLX3397)-treated group.Both radiofrequency electromagnetic fields and PLX3397 suppressed the levels of genes related to microgliosis(Csf1r,CD68,and Ccl6)and pro-inflammatory cytokine interleukin-1β.N otably,the expression levels of genes related to mic roglial function,including Trem2,Fcgr1α,Ctss,and Spi1,were decreased after long-term radiofrequency electromagnetic field exposure,which was also observed in response to microglial suppression by PLX3397.These results showed that radiofrequency electromagnetic fields ameliorated amyloid-βpathology and cognitive impairment by suppressing amyloid-βdeposition-induced microgliosis and their key regulator,CSF1R.
基金supported by the National Research Foundation of Korea(NRF)grants funded by the Korean Government(MSIT)(RS-2021-NR061841,RS-2024-00424551,RS-2024-00395393,and RS-2024-00346657)Korea Institute of Radiological and Medical Sciences(50531-2025)KIST Institutional Program(2E33712).
文摘Hypoglycemia is a frequent and potentially severe complication that can result in significant brain injury in individuals with diabetes treated with insulin or other hypoglycemic agents and in those undergoing prolonged fasting.Despite its clinical importance,the molecular mechanisms through which hypoglycemia induces neurodegeneration remain poorly defined.We therefore investigated the molecular and cellular basis of hypoglycemia-induced brain damage using human neuron and glial cell cultures in vitro and hypoglycemic mouse models in vivo.We found that starvation-induced hypoglycemia triggers hallmark neurodegenerative features,such as astrocyte activation and microglial reactivity,that closely resemble those found in the brains of hypoglycemic mouse models.Neurons notably activate an adaptive survival response mediated by serum response factor(SRF)and myocardin-related transcription factor-A(MRTF-A),which drives a metabolic reprogramming process.This shift enables neurons to use extracellular matrix components as alternative energy sources under glucose deprivation.However,this compensatory mechanism results in the excessive accumulation of urea cycle byproducts,which subsequently exacerbates neuronal damage and promotes glial activation.Glucose refeeding remarkably reversed these neurodegenerative features by deactivating SRF/MRTF-A signaling in both in vitro and in vivo.Collectively,our results revealed a neuron-intrinsic mechanism linking glucose deprivation to reversible neurodegeneration via SRF/MRTF-A,offering potential targets for preventing hypoglycemia-associated brain damage.
基金This research was supported by the Bio and Medical Technology Development Program of the National Research Foundation(NRF)grant of the Korea Institute of Radiological and Medical Sciences(KIRAMS)funded by the Korean government(MSIT,2019M3E5D1A01069361,2019R1A2C2087551,and 50535-2020).
文摘Dear Editor,Lung cancer is the most common cause of cancer-related mortality worldwide,with non-small cell lung cancer(NSCLC)accounting for the largest number of cases.1 Ionizing radiation(IR)is widely used as an indispensable tool for treating lung cancer patients;however,the acquisition of resistance following radiation is the major obstacle for reducing the efficacy of radiotherapy.
