The nanocrystalline Ho3+/Tm3+/Yb3+ co-doped CaWO4 upconversion(UC) phosphors were successfully synthesized by a modified citrate complex method using microwave irradiation. The citrate complex precursors were heat-tre...The nanocrystalline Ho3+/Tm3+/Yb3+ co-doped CaWO4 upconversion(UC) phosphors were successfully synthesized by a modified citrate complex method using microwave irradiation. The citrate complex precursors were heat-treated at temperature ranging from 300 to 700 °C for 3 h. Crystallization of the Ho3+/Tm3+/Yb3+ co-doped CaWO4 was detected at 400 °C, and entirely completed at 600 °C. The Ho3+/Tm3+/Yb3+ co-doped CaWO4 heat-treated at 600 °C showed primarily spherical and homogeneous morphology. Under the laser excitation of 980 nm, Ho3+/Tm3+/Yb3+ co-doped CaWO4 shows the bright white upconversion(UC) emission visible to the naked eye, which is composed of a blue emission at 475 nm from Tm3+, and green and red emissions at 543 and 651 nm respectively from Ho3+. The coordinates of Ho3+/Tm3+/Yb3+ co-doped CaWO4 in the Commission International De'eclairage(CIE) chromaticity diagram could be controlled from a cool to a warm white color depending on the Tm3+ and Ho3+ concentrations. The UC luminescent properties on Tm3+ and Ho3+ concentrations and related mechanism based on laser pump power were discussed in detail.展开更多
BACKGROUND： Many studies have suggested that one possible etiology of mild cognitive impairment is small vessel cerebrovascular disease, which is associated with small subcortical infarcts and white matter abnormalit...BACKGROUND： Many studies have suggested that one possible etiology of mild cognitive impairment is small vessel cerebrovascular disease, which is associated with small subcortical infarcts and white matter abnormalities. These white matter changes have been detected as white matter hyperintensity （WMH） using magnetic resonance imaging. WMH may be associated with frontal lobe dysfunction. OBJECTIVE： To examine white matter changes in mild cognitive impairment patients of different subtypes, and to evaluate the correlation between white matter changes and neuropsychological characteristics, demographic information, vascular risk factors, and mild cognitive impairment subtypes. DESIGN, TIME AND SETTING： The neurophysiological, comparison study was performed at the Department of Neurology Memory Clinic, Ulsan University Hospital, South Korea, between March 2007 and March 2008. PARTICIPANTS： Out of a total of 83 subjects with clinically diagnosed mild cognitive impairment at the out-patient clinic, 3 subjects with severe WMH were excluded. A total of 80 subjects were included in this study. No patients suffered from cognitive impairment induced by neurological diseases, mental disorders, or somatic diseases. In accordance with magnetic resonance imaging results, the patients were assigned to two subtypes： 56 subjects without WMH and 24 subjects with WMH. METHODS： All patients were subjected to a standard neuropsychological battery using the Korean version of the Mini-Mental State Examination, Clinical Dementia Rating, and comprehensive Seoul Neuropsychological Screening Battery. The Clinical Dementia Rating reflected general cognitive function of patients. Results from the Seoul Neuropsychological Screening Battery reflected attention, language function, visuospatial function, verbal memory, nonverbal memory, long-term memory, and frontal/executive function. Magnetic resonance imaging was used to map changes in the brain. MAIN OUTCOME MEASURES： The association between various white matter changes and neuropsychological characteristics, demographic information, vascular risk factors, and mild cognitive impairment subtypes was measured, based primarily on neuropsychological profiles using statistical methods. RESULTS： WMH was significantly associated with neuropsychological characteristics in MCI patients （P 〈 0.05 or P 〈 0.01）, in particular with frontal/executive dysfunction. WMH was significantly correlated with age （P = 0.022） and vascular risk factors （P = 0.006）, independent of gender and MCI subtypes. CONCLUSION： WMH was significantly associated with frontal/executive dysfunction in mild cognitive impairment.展开更多
Although the typical clinical signs of Parkinson disease (PD) are tremor, rigidity, bradykinesia, and postural instability, PD is preceded by a preclinical phase during which neuronal degeneration develops without typ...Although the typical clinical signs of Parkinson disease (PD) are tremor, rigidity, bradykinesia, and postural instability, PD is preceded by a preclinical phase during which neuronal degeneration develops without typical symptoms. More general nonspecific symptoms including dizziness have also been described to predate the typical PD signs for several years. All subjects were selected among patients in the Willis Hospital (Pusan, South of Korea), with complaints of diz-ziness from September 2009 to September 2010 and the baseline neurological screening and clinical ENT examination, to which the results were within the normal range. At baseline, 113 participants underwent neurological screening and provided information on dizziness. Of those participants, 103 were enrolled including 63 subjects in the control group. We used posturography. It allows quantitative assessment of vestibular-spinal component of body balance. The parame-ter of average speed of pressure center displacement to the lateral plan (VMX) and antero-posterior plan (VMY), which presented statistically significant differences between the groups except VMX with closed eyes. (p = 0.008 and p = 0.012, with closed eyes). With open eyes, only VMY showed significant difference between the groups (p = 0.010). In this study, the patients with dizziness and subjective complaints related to typical clinical signs of PD complaints presented higher instability in the orthostatic position than the control group of patients with dizziness and without such complaint. It could suggest that dizziness may be one symptom of preclinical PD and progress to overt postural instability. It is believed that a stepwise approach with a simple and inexpensive initial screening test of preclinical PD is required.展开更多
基金supported by a grant from the LINC (Leaders in INdustry-university Cooperation) Program of Korea National University of Transportation in 2013
文摘The nanocrystalline Ho3+/Tm3+/Yb3+ co-doped CaWO4 upconversion(UC) phosphors were successfully synthesized by a modified citrate complex method using microwave irradiation. The citrate complex precursors were heat-treated at temperature ranging from 300 to 700 °C for 3 h. Crystallization of the Ho3+/Tm3+/Yb3+ co-doped CaWO4 was detected at 400 °C, and entirely completed at 600 °C. The Ho3+/Tm3+/Yb3+ co-doped CaWO4 heat-treated at 600 °C showed primarily spherical and homogeneous morphology. Under the laser excitation of 980 nm, Ho3+/Tm3+/Yb3+ co-doped CaWO4 shows the bright white upconversion(UC) emission visible to the naked eye, which is composed of a blue emission at 475 nm from Tm3+, and green and red emissions at 543 and 651 nm respectively from Ho3+. The coordinates of Ho3+/Tm3+/Yb3+ co-doped CaWO4 in the Commission International De'eclairage(CIE) chromaticity diagram could be controlled from a cool to a warm white color depending on the Tm3+ and Ho3+ concentrations. The UC luminescent properties on Tm3+ and Ho3+ concentrations and related mechanism based on laser pump power were discussed in detail.
基金the Korea Health 21 R&D Project, Ministry of Health and Welfare,and the Republic of Korea.No.A050079
文摘BACKGROUND： Many studies have suggested that one possible etiology of mild cognitive impairment is small vessel cerebrovascular disease, which is associated with small subcortical infarcts and white matter abnormalities. These white matter changes have been detected as white matter hyperintensity （WMH） using magnetic resonance imaging. WMH may be associated with frontal lobe dysfunction. OBJECTIVE： To examine white matter changes in mild cognitive impairment patients of different subtypes, and to evaluate the correlation between white matter changes and neuropsychological characteristics, demographic information, vascular risk factors, and mild cognitive impairment subtypes. DESIGN, TIME AND SETTING： The neurophysiological, comparison study was performed at the Department of Neurology Memory Clinic, Ulsan University Hospital, South Korea, between March 2007 and March 2008. PARTICIPANTS： Out of a total of 83 subjects with clinically diagnosed mild cognitive impairment at the out-patient clinic, 3 subjects with severe WMH were excluded. A total of 80 subjects were included in this study. No patients suffered from cognitive impairment induced by neurological diseases, mental disorders, or somatic diseases. In accordance with magnetic resonance imaging results, the patients were assigned to two subtypes： 56 subjects without WMH and 24 subjects with WMH. METHODS： All patients were subjected to a standard neuropsychological battery using the Korean version of the Mini-Mental State Examination, Clinical Dementia Rating, and comprehensive Seoul Neuropsychological Screening Battery. The Clinical Dementia Rating reflected general cognitive function of patients. Results from the Seoul Neuropsychological Screening Battery reflected attention, language function, visuospatial function, verbal memory, nonverbal memory, long-term memory, and frontal/executive function. Magnetic resonance imaging was used to map changes in the brain. MAIN OUTCOME MEASURES： The association between various white matter changes and neuropsychological characteristics, demographic information, vascular risk factors, and mild cognitive impairment subtypes was measured, based primarily on neuropsychological profiles using statistical methods. RESULTS： WMH was significantly associated with neuropsychological characteristics in MCI patients （P 〈 0.05 or P 〈 0.01）, in particular with frontal/executive dysfunction. WMH was significantly correlated with age （P = 0.022） and vascular risk factors （P = 0.006）, independent of gender and MCI subtypes. CONCLUSION： WMH was significantly associated with frontal/executive dysfunction in mild cognitive impairment.
文摘Although the typical clinical signs of Parkinson disease (PD) are tremor, rigidity, bradykinesia, and postural instability, PD is preceded by a preclinical phase during which neuronal degeneration develops without typical symptoms. More general nonspecific symptoms including dizziness have also been described to predate the typical PD signs for several years. All subjects were selected among patients in the Willis Hospital (Pusan, South of Korea), with complaints of diz-ziness from September 2009 to September 2010 and the baseline neurological screening and clinical ENT examination, to which the results were within the normal range. At baseline, 113 participants underwent neurological screening and provided information on dizziness. Of those participants, 103 were enrolled including 63 subjects in the control group. We used posturography. It allows quantitative assessment of vestibular-spinal component of body balance. The parame-ter of average speed of pressure center displacement to the lateral plan (VMX) and antero-posterior plan (VMY), which presented statistically significant differences between the groups except VMX with closed eyes. (p = 0.008 and p = 0.012, with closed eyes). With open eyes, only VMY showed significant difference between the groups (p = 0.010). In this study, the patients with dizziness and subjective complaints related to typical clinical signs of PD complaints presented higher instability in the orthostatic position than the control group of patients with dizziness and without such complaint. It could suggest that dizziness may be one symptom of preclinical PD and progress to overt postural instability. It is believed that a stepwise approach with a simple and inexpensive initial screening test of preclinical PD is required.
