73 results on '"Wu PM"'
Search Results
2. SU-E-T-534: Level of Residual Radioactivity of Activated Parts of a Decommissioned Cyclotron
- Author
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Choi, HHF, primary, Leung, TM, additional, Chiu, TL, additional, Yang, B, additional, Wu, PM, additional, Cheung, KY, additional, and Yu, SK, additional
- Published
- 2015
- Full Text
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3. An unidentified yet notable modification on I Na and I K (DR) caused by ramelteon.
- Author
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Wu PM, Tu YF, Cho HY, Yu MC, Wu YH, and Wu SN
- Abstract
Despite advancement in anti-seizure medications, 30% of patients continue to experience recurrent seizures. Previous data indicated the antiepileptic properties of melatonin and its agonists in several animal models. However, the underlying mechanisms of melatonin and its agonists on cellular excitability remain poorly understood. In this study, we demonstrated the electrophysiological changes of two main kinds of ion channels that are responsible for hyperexcitability of neurons after introduction of melatonin agonists- ramelteon (RAM). In Neuro-2a cells, the amplitude of voltage-gated Na
+ ( INa ) and delayed-rectifier K+ currents ( IK (DR) ) could be suppressed under RAM. The IC50 values of 8.7 and 2.9 μM, respectively. RAM also diminished the magnitude of window Na+ current ( INa (W) ) elicited by short ascending ramp voltage, with unchanged the overall steady-state current-voltage relationship. The decaying time course of INa during a train of depolarizing pulses arose upon the exposure to RAM. The conditioning train protocol which blocked INa fitted the recovery time course into two exponential processes and increased the fast and slow time constant of recovery the presence of RAM. In pituitary tumor (GH3 ) cells, INa amplitude was also effectively suppressed by the RAM. In addition, GH3-cells exposure to RAM decreased the firing frequency of spontaneous action potentials observed under current-clamp conditions. As a result, the RAM-mediated effect on INa was closely associated with its ability to decrease spontaneous action potentials. Collectively, we found the direct attenuation of INa and IK (DR) caused by RAM besides the agonistic action on melatonin receptors, which could partially explain its anti-seizure activity., (© 2024 The Authors. FASEB BioAdvances published by Wiley Periodicals LLC on behalf of The Federation of American Societies for Experimental Biology.)- Published
- 2024
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4. Advanced TiO 2 /Al 2 O 3 Bilayer ALD Coatings for Improved Lithium-Rich Layered Oxide Electrodes.
- Author
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Chen WM, Hsieh HY, Wu DZ, Tang HY, Chang-Liao KS, Chi PW, Wu PM, and Wu MK
- Abstract
Surface modification is a highly effective strategy for addressing issues in lithium-rich layered oxide (LLO) cathodes, including phase transformation, particle cracking, oxygen gas release, and transition-metal ion dissolution. Existing single-/double-layer coating strategies face drawbacks such as poor component contact and complexity. Herein, we present the results of a low-temperature atomic layer deposition (ALD) process for creating a TiO
2 /Al2 O3 bilayer on composite cathodes made of AS200 (Li1.08 Ni0.34 Co0.08 Mn0.5 O2 ). Electrochemical analysis demonstrates that TiO2 /Al2 O3 -coated LLO electrodes exhibit improved discharge capacities and enhanced capacity retention compared with uncoated samples. The TAA-5/AS200 bilayer-coated electrode, in particular, demonstrates exceptional capacity retention (∼90.4%) and a specific discharge capacity of 146 mAh g-1 after 100 cycles at 1C within the voltage range of 2.2 to 4.6 V. The coated electrodes also show reduced voltage decay, lower surface film resistance, and improved interfacial charge transfer resistances, contributing to enhanced stability. The ALD-deposited TiO2 /Al2 O3 bilayer coatings exhibit promising potential for advancing the electrochemical performance of lithium-rich layered oxide cathodes in lithium-ion batteries.- Published
- 2024
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5. Deep Learning Combined with Radiologist's Intervention Achieves Accurate Segmentation of Hepatocellular Carcinoma in Dual-Phase Magnetic Resonance Images.
- Author
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Ye Y, Zhang N, Wu D, Huang B, Cai X, Ruan X, Chen L, Huang K, Li ZP, Wu PM, Jiang J, Dan G, and Peng Z
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- Humans, Image Processing, Computer-Assisted methods, Magnetic Resonance Imaging methods, Radiologists, Carcinoma, Hepatocellular diagnostic imaging, Deep Learning, Liver Neoplasms diagnostic imaging
- Abstract
Purpose: Segmentation of hepatocellular carcinoma (HCC) is crucial; however, manual segmentation is subjective and time-consuming. Accurate and automatic lesion contouring for HCC is desirable in clinical practice. In response to this need, our study introduced a segmentation approach for HCC combining deep convolutional neural networks (DCNNs) and radiologist intervention in magnetic resonance imaging (MRI). We sought to design a segmentation method with a deep learning method that automatically segments using manual location information for moderately experienced radiologists. In addition, we verified the viability of this method to assist radiologists in accurate and fast lesion segmentation., Method: In our study, we developed a semiautomatic approach for segmenting HCC using DCNN in conjunction with radiologist intervention in dual-phase gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid- (Gd-EOB-DTPA-) enhanced MRI. We developed a DCNN and deep fusion network (DFN) trained on full-size images, namely, DCNN-F and DFN-F. Furthermore, DFN was applied to the image blocks containing tumor lesions that were roughly contoured by a radiologist with 10 years of experience in abdominal MRI, and this method was named DFN-R. Another radiologist with five years of experience (moderate experience) performed tumor lesion contouring for comparison with our proposed methods. The ground truth image was contoured by an experienced radiologist and reviewed by an independent experienced radiologist., Results: The mean DSC of DCNN-F, DFN-F, and DFN-R was 0.69 ± 0.20 (median, 0.72), 0.74 ± 0.21 (median, 0.77), and 0.83 ± 0.13 (median, 0.88), respectively. The mean DSC of the segmentation by the radiologist with moderate experience was 0.79 ± 0.11 (median, 0.83), which was lower than the performance of DFN-R., Conclusions: Deep learning using dual-phase MRI shows great potential for HCC lesion segmentation. The radiologist-aided semiautomated method (DFN-R) achieved improved performance compared to manual contouring by the radiologist with moderate experience, although the difference was not statistically significant., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2024 Yufeng Ye et al.)
- Published
- 2024
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6. Corrigendum to "miR-196a provides antioxidative neuroprotection via USP15/Nrf2 regulation in Huntington's disease" [Free Radic. Biol. Med. 209 (2023) 292-300].
- Author
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Chan SC, Tung CW, Lin CW, Tung YS, Wu PM, Cheng PH, Chen CM, and Yang SH
- Published
- 2024
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7. miR-196a provides antioxidative neuroprotection via USP15/Nrf2 regulation in Huntington's disease.
- Author
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Chan SC, Tung CW, Lin CW, Tung YS, Wu PM, Cheng PH, Chen CM, and Yang SH
- Subjects
- Humans, Neuroprotection genetics, Antioxidants, NF-E2-Related Factor 2 genetics, Reactive Oxygen Species, Ubiquitin-Specific Proteases, MicroRNAs genetics, MicroRNAs metabolism, Huntington Disease genetics, Huntington Disease metabolism
- Abstract
Huntington's disease (HD) is a devastating neurodegenerative disorder characterized by the accumulation of mutant Huntingtin protein (mHTT) and oxidative stress-induced neuronal damage. Based on previous reports, microRNA-196a (miR-196a) has emerged as a potential therapeutic target due to its neuroprotective effects in various neurodegenerative diseases. However, whether miR-196a functions through antioxidative effects is still unknown. In this study, we demonstrated that HD models, both in vitro and in vivo, exhibit elevated levels of reactive oxygen species (ROS) and increased neuronal death, and miR-196a mitigates ROS levels and reduces cell death in HD cells. Moreover, we elucidated that miR-196a facilitates the translocation of nuclear factor erythroid 2 (Nrf2) into the nucleus, enhancing the transcription of antioxidant genes, including heme oxygenase-1 (HO-1). We further identified ubiquitin-specific peptidase 15 (USP15), a direct target of miR-196a related to the Nrf2 pathway, and USP15 exacerbates mHTT aggregate formation while partially counteracting miR-196a-induced reductions in mHTT levels. Taken together, these findings shed light on the multifaceted role of miR-196a in HD, highlighting its potential as a therapeutic avenue for ameliorating oxidative stress and neurodegeneration in this debilitating disease., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)
- Published
- 2023
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8. Association of Cystic Periventricular Leukomalacia and Postnatal Epilepsy in Very Preterm Infants.
- Author
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Wu PM, Wu CY, Li CI, Huang CC, and Tu YF
- Subjects
- Infant, Female, Infant, Newborn, Humans, Infant, Premature, Prospective Studies, Fetal Growth Retardation, Seizures epidemiology, Seizures etiology, Infant, Very Low Birth Weight, Leukomalacia, Periventricular epidemiology, Leukomalacia, Periventricular complications, Cerebral Palsy diagnosis, Infant, Premature, Diseases epidemiology, Infant, Premature, Diseases diagnosis, Epilepsy etiology, Epilepsy complications
- Abstract
Introduction: Cystic periventricular leukomalacia (PVL) is the most common white matter injury and a common cause of cerebral palsy in preterm infants. Postnatal epilepsy may occur after cystic PVL, but their causal relationship remains uncertain. Our aim was to validate the contribution of cystic PVL to postnatal epilepsy in very preterm infants and demonstrate their seizure characteristics., Methods: This prospective cohort study enrolled 1,342 preterm infants (birth weight <1,500 g and gestational age <32 weeks) from 2003 to 2015. Cystic PVL was diagnosed by serial cerebral ultrasound, and other comorbidities were recorded during hospitalization. Neurological developments and consequences, including epilepsy, were serially accessed until the age of 5., Results: A total of 976 preterm infants completed a 5-year neurological follow-up; 47 (4.8%) had cystic PVL. Preterm infants with cystic PVL were commonly associated with other comorbidities, including necrotizing enterocolitis stage III, neonatal seizures, and intraventricular hemorrhage during hospitalization. At age 5, 14 of the 47 (29.8%) preterm infants with cystic PVL had postnatal epilepsy. After adjusting for gender, gestational age, and three common comorbidities, cystic PVL was an independent risk factor for postnatal epilepsy (adjust OR: 16.2; 95% CI: 6.8-38.4; p < 0.001). Postnatal epilepsy after cystic PVL was commonly the generalized type (13 of 14, 92.9%), not intractable and most occurred after 1 year of age., Discussion/conclusion: Cystic PVL would independently lead to postnatal epilepsy. Preterm infants with cystic PVL are at risk of postnatal epilepsy after age 1 in addition to cerebral palsy., (© 2023 S. Karger AG, Basel.)
- Published
- 2023
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9. Effective Modulation by Lacosamide on Cumulative Inhibition of I Na during High-Frequency Stimulation and Recovery of I Na Block during Conditioning Pulse Train.
- Author
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Wu PM, Lin YC, Chiang CW, Cho HY, Chuang TH, Yu MC, Wu SN, and Tu YF
- Subjects
- Ions metabolism, Lacosamide pharmacology, Veratridine, Sodium metabolism, Sodium Channels
- Abstract
The effects of lacosamide (LCS, Vimpat
® ), an anti-convulsant and analgesic, on voltage-gated Na+ current ( INa ) were investigated. LCS suppressed both the peak (transient, INa(T) ) and sustained (late, INa(L) ) components of INa with the IC50 values of 78 and 34 μM found in GH3 cells and of 112 and 26 μM in Neuro-2a cells, respectively. In GH3 cells, the voltage-dependent hysteresis of persistent INa ( INa(P) ) during the triangular ramp pulse was strikingly attenuated, and the decaying time constant (τ) of INa(T) or INa(L) during a train of depolarizing pulses was further shortened by LCS. The recovery time course from the INa block elicited by the preceding conditioning train can be fitted by two exponential processes, while the single exponential increase in current recovery without a conditioning train was adequately fitted. The fast and slow τ's of recovery from the INa block by the same conditioning protocol arose in the presence of LCS. In Neuro-2a cells, the strength of the instantaneous window INa ( INa(W) ) during the rapid ramp pulse was reduced by LCS. This reduction could be reversed by tefluthrin. Moreover, LCS accelerated the inactivation time course of INa activated by pulse train stimulation, and veratridine reversed its decrease in the decaying τ value in current inactivation. The docking results predicted the capability of LCS binding to some amino-acid residues in sodium channels owing to the occurrence of hydrophobic contact. Overall, our findings unveiled that LCS can interact with the sodium channels to alter the magnitude, gating, voltage-dependent hysteresis behavior, and use dependence of INa in excitable cells.- Published
- 2022
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10. Effective Perturbations by Phenobarbital on I Na , I K(erg) , I K(M) and I K(DR) during Pulse Train Stimulation in Neuroblastoma Neuro-2a Cells.
- Author
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Wu PM, Lai PC, Cho HY, Chuang TH, Wu SN, and Tu YF
- Abstract
Phenobarbital (PHB, Luminal Sodium
® ) is a medication of the barbiturate and has long been recognized to be an anticonvulsant and a hypnotic because it can facilitate synaptic inhibition in the central nervous system through acting on the γ-aminobutyric acid (GABA) type A (GABAA ) receptors. However, to what extent PHB could directly perturb the magnitude and gating of different plasmalemmal ionic currents is not thoroughly explored. In neuroblastoma Neuro-2a cells, we found that PHB effectively suppressed the magnitude of voltage-gated Na+ current ( INa ) in a concentration-dependent fashion, with an effective IC50 value of 83 µM. The cumulative inhibition of INa , evoked by pulse train stimulation, was enhanced by PHB. However, tefluthrin, an activator of INa , could attenuate PHB-induced reduction in the decaying time constant of INa inhibition evoked by pulse train stimuli. In addition, the erg ( ether-à-go-go -related gene)-mediated K+ current ( IK(erg) ) was also blocked by PHB. The PHB-mediated inhibition on IK(erg) could not be overcome by flumazenil (GABA antagonist) or chlorotoxin (chloride channel blocker). The PHB reduced the recovery of IK(erg) by a two-step voltage protocol with a geometrics-based progression, but it increased the decaying rate of IK(erg) , evoked by the envelope-of-tail method. About the M-type K+ currents ( IK(M) ), PHB caused a reduction of its amplitude, which could not be counteracted by flumazenil or chlorotoxin, and PHB could enhance its cumulative inhibition during pulse train stimulation. Moreover, the magnitude of delayed-rectifier K+ current ( IK(DR) ) was inhibited by PHB, while the cumulative inhibition of IK(DR) during 10 s of repetitive stimulation was enhanced. Multiple ionic currents during pulse train stimulation were subject to PHB, and neither GABA antagonist nor chloride channel blocker could counteract these PHB-induced reductions. It suggests that these actions might conceivably participate in different functional activities of excitable cells and be independent of GABAA receptors.- Published
- 2022
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11. Vibrational and electrochemical studies of pectin-a candidate towards environmental friendly lithium-ion battery development.
- Author
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Wu PM, Chung CY, Chen YR, Su YH, Chang-Liao KS, Chi PW, Paul T, Chen YJ, Chen YL, Wang SF, Badgujar P, Chen BN, Cheng CL, and Wu MK
- Abstract
Pectin polymers are considered for lithium-ion battery electrodes. To understand the performance of pectin as an applied buffer layer, the electrical, magnetic, and optical properties of pectin films are investigated. This work describes a methodology for creating pectin films, including both pristine pectin and Fe-doped pectin, which are optically translucent, and explores their potential for lithium-ion battery application. The transmission response is found extended in optimally Fe-doped pectin, and prominent modes for cation bonding are identified. Fe doping enhances the conductivity observed in electrochemical impedance spectroscopy, and from the magnetic response of pectin evidence for Fe
3+ is identified. The Li-ion half-cell prepared with pectin as binder for anode materials such as graphite shows stable charge capacity over long cycle life, and with slightly higher specific capacity compare with the cell prepared using polyvinylidene fluoride (PVDF) as binder. A novel enhanced charging specific capacity at a high C-rate is observed in cells with pectin binder, suggesting that within a certain rate (∼5 C), pectin has higher capacity at faster charge rates. The pectin system is found as a viable base material for organic-inorganic synthesis studies., (© The Author(s) 2022. Published by Oxford University Press on behalf of National Academy of Sciences.)- Published
- 2022
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12. Characterization in Inhibitory Effectiveness of Carbamazepine in Voltage-Gated Na + and Erg-Mediated K + Currents in a Mouse Neural Crest-Derived (Neuro-2a) Cell Line.
- Author
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Wu PM, Cho HY, Chiang CW, Chuang TH, Wu SN, and Tu YF
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- Animals, Benzodiazepines, Carbamazepine pharmacology, Cell Line, Mice, Sodium, Anticonvulsants pharmacology, Neural Crest
- Abstract
Carbamazepine (CBZ, Tegretol
® ) is an anticonvulsant used in the treatment of epilepsy and neuropathic pain; however, several unwanted effects of this drug have been noticed. Therefore, the regulatory actions of CBZ on ionic currents in electrically excitable cells need to be reappraised, although its efficacy in suppressing voltage-gated Na+ current ( INa ) has been disclosed. This study was undertaken to explore the modifications produced by CBZ on ionic currents (e.g., INa and erg -mediated K+ current [ IK(erg) ]) measured from Neuro-2a (N2a) cells. In these cells, we found that this drug differentially suppressed the peak (transient, INa(T) ) and sustained (late, INa(L) ) components of INa in a concentration-dependent manner with effective IC50 of 56 and 18 μM, respectively. The overall current-voltage relationship of INa(T) with or without the addition of CBZ remained unchanged; however, the strength (i.e., ∆area) in the window component of INa ( INa(W) ) evoked by the short ascending ramp pulse (Vramp ) was overly lessened in the CBZ presence. Tefluthrin (Tef), a synthetic pyrethroid, known to stimulate INa , augmented the strength of the voltage-dependent hysteresis (Hys(V) ) of persistent INa ( INa(P) ) in response to the isosceles-triangular Vramp ; moreover, further application of CBZ attenuated Tef-mediated accentuation of INa(P) 's Hys(V) . With a two-step voltage protocol, the recovery of INa(T) inactivation seen in Neuro-2a cells became progressively slowed by adding CBZ; however, the cumulative inhibition of INa(T) evoked by pulse train stimulation was enhanced during exposure to this drug. Neuro-2a-cell exposure to CBZ (100 μM), the magnitude of erg -mediated K+ current measured throughout the entire voltage-clamp steps applied was mildly inhibited. The docking results regarding the interaction of CBZ and voltage-gate Na+ (NaV ) channel predicted the ability of CBZ to bind to some amino-acid residues in NaV due to the existence of a hydrogen bond or hydrophobic contact. It is conceivable from the current investigations that the INa ( INa(T) , INa(L) , INa(W) , and INa(P) ) residing in Neuro-2a cells are susceptible to being suppressed by CBZ, and that its block on INa(L) is larger than that on INa(T) . Collectively, the magnitude and gating of NaV channels produced by the CBZ presence might have an impact on its anticonvulsant and analgesic effects occurring in vivo.- Published
- 2022
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13. Hybrid split-arc partial-field volumetric modulated arc therapy: an improved beam arrangement for linear accelerator-based hippocampal-avoidance whole brain radiation therapy.
- Author
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Yuen AHL, Wu PM, Li AKL, and Mak PCY
- Abstract
Background: This technical note aims to verify the hippocampus and adjacent organs at risk (OARs) sparing ability of an improved beam arrangement, namely hybrid split-arc partial-field volumetric modulated arc therapy (VMAT) (Hsapf-VMAT) during whole brain radiation therapy (WBRT)., Materials and Methods: Computed tomography simulation images of 22 patients with brain metastases were retrieved in this retrospective planning study. The hippocampus was manually delineated according to the criterion of RTOG 0933. Plans delivering 30 Gy in 10 fractions were generated for each patient using split-arc partial-field VMAT (sapf-VMAT) and Hsapf-VMAT. The sapf-VMAT plans consisted of 4 arc fields of 179.9° each with reduced field size. The Hsapf-VMAT consisted of 4 arc fields similar to sapf-VMAT in addition to 2 lateral opposing static fields. Statistical comparisons between treatment plans of both techniques were performed using the paired t-test at 5% level significance., Results: The results demonstrated that Hsapf-VMAT can achieve superior dose sparing in hippocampus which is comparable to sapf-VMAT (p > 0.05). In both eyes, Hsapf-VMAT had significantly lower D
mean and Dmax compared to sapf-VMAT (p < 0.005). Decrease in Dmax of both lenses using Hsapf-VMAT (p < 0.005) were statistically significant when compared to sapf-VMAT. Hsapf-VMAT demonstrated significant reduction of Dmean and Dmedian to the optic nerves (p < 0.05). Whole brain planning target volume (PTV) coverage was not compromised in both techniques., Conclusion: The present study adopts a hybrid technique, namely Hsapf-VMAT, for hippocampal sparing WBRT. Hsapf-VMAT can achieve promising dose reduction to the hippocampus, both eyes and lenses. Therefore, Hsapf-VMAT can be considered an improved version of sapf-VMAT., Competing Interests: Conflict of interests None declared. Funding The authors declare no competing financial interests., (© 2022 Greater Poland Cancer Centre.)- Published
- 2022
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14. A study on Ti-doped Fe 3 O 4 anode for Li ion battery using machine learning, electrochemical and distribution function of relaxation times (DFRTs) analyses.
- Author
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Chi PW, Paul T, Su YH, Su KH, Su CY, Wu PM, Wang SF, and Wu MK
- Abstract
Among many transition-metal oxides, Fe
3 O4 anode based lithium ion batteries (LIBs) have been well-investigated because of their high energy and high capacity. Iron is known for elemental abundance and is relatively environmentally friendly as well contains with low toxicity. However, LIBs based on Fe3 O4 suffer from particle aggregation during charge-discharge processes that affects the cycling performance. This study conjectures that iron agglomeration and material performance could be affected by dopant choice, and improvements are sought with Fe3 O4 nanoparticles doped with 0.2% Ti. The electrochemical measurements show a stable specific capacity of 450 mAh g-1 at 0.1 C rate for at least 100 cycles in Ti doped Fe3 O4 . The stability in discharge capacity for Ti doped Fe3 O4 is achieved, arising from good electronic conductivity and stability in microstructure and crystal structure, which has been further confirmed by density functional theory (DFT) calculation. Detailed distribution function of relaxation times (DFRTs) analyses based on the impedance spectra reveal two different types of Li ion transport phenomena, which are closely related with the electron density difference near the two Fe-sites. Detailed analyses on EIS measurements using DFRTs for Ti doped Fe3 O4 indicate that improvement in interfacial charge transfer processes between electrode and Li metal along with an intermediate lithiated phase helps to enhance the electrochemical performance., (© 2022. The Author(s).)- Published
- 2022
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15. Novel Variations in the KDM5C Gene Causing X-Linked Intellectual Disability.
- Author
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Wu PM, Yu WH, Chiang CW, Wu CY, Chen JS, and Tu YF
- Abstract
Background and Objectives: To investigate the pathogenicity of 2 novel KDM5C variations, report the clinical and neuroimaging findings, and review the available literature., Methods: Physical examinations, structural neuroimaging studies, and exome sequence analysis were performed. KDM5C constructs were used to study the effect of the variations in transfected cells., Results: We identified 2 novel variations c.2233C>G and c.3392_3393delAG in the KDM5C gene harboring from 2 Chinese families with X-linked intellectual disability (ID). The affected male patients exhibited severe ID, short stature, and facial dysmorphism. The 1 with c.3392_3393delAG additionally had epilepsy and autistic spectrum disorder (ASD). Transiently transfected mutant KDM5C constructs both reduced protein expression and stability and decreased histone demethylase activities in cells. Reviewing the available literature, we found that the associated ASD tended to occur in patients with variations near the C-terminus of KDM5C., Discussion: We report the clinical, molecular genetic, and pathologic features in patients with novel variations of KDM5C . The variability of the clinical phenotype in addition to an ID may associate with altered particular parts of KDM5C., (Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)
- Published
- 2021
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16. Lactate Predicts Neurological Outcomes after Perinatal Asphyxia in Post-Hypothermia Era: A Prospective Cohort Study.
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Tu YF, Wu PM, Yu WH, Li CI, Wu CL, Kang L, Lin YC, Shih HI, and Huang CC
- Abstract
Background: Neonatal hypoxic-ischemic encephalopathy (HIE) is the most common cause of mortality and neurological disability in infancy after perinatal asphyxia. Reliable biomarkers to predict neurological outcomes of neonates after perinatal asphyxia are still not accessible in clinical practice., Methods: A prospective cohort study enrolled neonates with perinatal asphyxia. Biochemical blood tests and cerebral Doppler ultrasound were measured within 6 h of age and at the 4th day old. Neurological outcomes were assessed at 1 year old., Results: Sixty-four neonates with perinatal asphyxia were enrolled. Fifty-eight (90%) had hypoxic-ischemic encephalopathy (HIE) including 20 (34%) Stage I, 21 (36%) Stage II, and 17 (29%) Stage III. In the asphyxiated infants without therapeutic hypothermia, HIE stage, PH, and base excess levels within 6 h of age were the predictors of adverse outcomes. In the asphyxiated infants receiving therapeutic hypothermia, HIE stage failed to predict outcomes. Instead, blood lactate levels and pulsatility index (PI) of medial cerebral arteries (MCA) either in 6 h of age or at the 4th day old independently predicted adverse outcomes., Conclusions: Blood lactate, which is a common accessible test at the hospital and MCA PI on cerebral ultrasound could predict adverse outcomes in asphyxiated infants receiving therapeutic hypothermia.
- Published
- 2021
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17. Electrochemical Performance of Orthorhombic CsPbI 3 Perovskite in Li-Ion Batteries.
- Author
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Kaisar N, Paul T, Chi PW, Su YH, Singh A, Chu CW, Wu MK, and Wu PM
- Abstract
A facile solution process was employed to prepare CsPbI
3 as an anode material for Li-ion batteries. Rietveld refinement of the X-ray data confirms the orthorhombic phase of CsPbI3 at room temperature. As obtained from bond valence calculations, strained bonds between Pb and I are identified within PbI6 octahedral units. Morphological study shows that the as-prepared δ-CsPbI3 forms a nanorod-like structure. The XPS analysis confirm the presence of Cs (3d, 4d), Pb (4d, 4f, 5d) and I (3p, 3d, 4d). The lithiation process involves both intercalation and conversion reactions, as confirmed by cyclic voltammetry (CV) and first-principles calculations. Impedance spectroscopy coupled with the distribution function of relaxation times identifies charge transfer processes due to Li metal foil and anode/electrolyte interfaces. An initial discharge capacity of 151 mAhg-1 is found to continuously increase to reach a maximum of ~275 mAhg-1 at 65 cycles, while it drops to ~240 mAhg-1 at 75 cycles and then slowly decreases to 235 mAhg-1 at 100 cycles. Considering the performance and structural integrity during electrochemical performance, δ-CsPbI3 is a promising material for future Li-ion battery (LIB) application.- Published
- 2021
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18. Precocious puberty as a consequence of anti-NMDA receptor encephalitis in children.
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Wu PM, Teng CK, Chou YY, and Tu YF
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- Adolescent, Brain, Child, Child, Preschool, Female, Humans, Male, Receptors, N-Methyl-D-Aspartate, Retrospective Studies, Anti-N-Methyl-D-Aspartate Receptor Encephalitis diagnosis, Anti-N-Methyl-D-Aspartate Receptor Encephalitis therapy, Puberty, Precocious etiology
- Abstract
Background: Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is one of the most common autoimmune encephalitis in children. Most children recovered well after anti-NMDA receptor encephalitis. However, the NMDA receptor network functions are critical for the developing brain in children. The long-term consequences in pediatric patients of anti-NMDA receptor encephalitis are very infrequently reported., Methods: This case series study retrospectively enrolled 10 children aged below 18 years old with antibody-proved anti-NMDA receptor encephalitis in a tertiary medical center from 2010 to 2019. Long-term neurological consequences of anti-NMDA receptor encephalitis in children were followed., Results: One boy and nine girls were enrolled with a median onset age of 3.6 years. The most common initial presentation was verbal reduction and psychiatric symptoms soon after some flu-like prodromal symptoms. Nearly all patients then developed decreased level of consciousness, mutism, seizures and orofacial-lingual dyskinesia. Autonomic instability occurred in 5 patients, particularly in pre-pubertal children. Only one adolescent patient had ovarian teratoma. All patients survived after immunotherapy and were followed for 5.8 ± 3.3 years after discharge. Four had epilepsy within 2 years after encephalitis, four had a cognitive deficit, one had mild psychiatric symptoms of hallucination, and none had residual involuntary movements. Moreover, two pre-pubertal children developed central precocious puberty about 3 years after encephalitis, and one required gonadotropin-releasing hormone agonist treatment., Conclusion: Central precocious puberty could be a consequence of anti-NMDA receptor encephalitis in the pre-pubertal children. The pediatrician should pay attention to its occurrence at follow-up., Competing Interests: Declaration of competing interest All authors declare no any conflict of interest., (Copyright © 2021. Published by Elsevier B.V.)
- Published
- 2021
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19. Computation of distribution of relaxation times by Tikhonov regularization for Li ion batteries: usage of L-curve method.
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Paul T, Chi PW, Wu PM, and Wu MK
- Abstract
In this paper, the distribution of relaxation times (DRTs) functions are calculated numerically in Matlab for synthetic impedance data from single parallel [Formula: see text] circuit and two parallel [Formula: see text] circuits connected in series, experimental impedance data from supercapacitors and α-LiFeO
2 anode based Li ion batteries. The quality of the impedance data is checked with the Kramers-Krönig (KK) relations. The DRTs are calculated within the KK compatible regime for all the systems using Tikhonov regularization (TR) method. Here we use a fast and simple L-curve method to estimate the TR parameter (λ) for regularization of the Fredholm integral equations of first kind in impedance. Estimation of the regularization parameters are performed effectively from the offset of the global corner of the L-curve rather than simply using the global corner. The physical significances of DRT peaks are also discussed by calculating the effective resistances and capacitances coupled with peak fitting program. For instance, two peaks in the DRTs justify the electrical double layer capacitance and ion diffusion phenomena for supercapacitors in low to intermediate frequencies respectively. Moreover, the surface film effect, Li/electrolyte and electrode/electrolyte charge transfer related processes are identified for α-LiFeO2 anode based Li-ion batteries. This estimation of the offset of the global corner extends the L-curve approach coupled with the Tikhonov regularization in the field of electrochemistry and can also be applied in similar process detection methods.- Published
- 2021
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20. Early Blood Biomarkers Distinguish Inflammation from Neonatal Hypoxic-Ischemia Encephalopathy.
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Wu PM, Lin CH, Lee HT, Shih HI, Huang CC, and Tu YF
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- Animals, Animals, Newborn, Biomarkers blood, Diagnosis, Differential, Rats, Sprague-Dawley, Glial Fibrillary Acidic Protein blood, Hypoxia-Ischemia, Brain diagnosis, Inflammation diagnosis, Osteopontin blood
- Abstract
Neonatal hypoxic-ischemic encephalopathy is the most common cause of neurological disability in infancy. Superimposed inflammation may further worsen neurological outcomes. Reliable biomarkers which are both sensitive to hypoxic-ischemia and inflammation are critically needed. We tested plasma osteopontin (OPN) and glial fibrillary astrocytic protein (GFAP) within the reported therapeutic window (90 min after hypoxic-ischemic (HI) injury) in neonatal rats with different HI severity and inflammation. Two different HI severity groups (mild-HI with 75 min hypoxia and severe-HI with 150 min hypoxia) were established. Inflammation-sensitized HI brain injury induced by lipopolysaccharide (LPS) further increased apoptotic neurons and infarct volumes. In HI alone groups, OPN was significantly decreased (p < 0.001) but GFAP was slightly increased (p < 0.05) at 90 min after HI either in mild-HI or severe-HI compared with naïve group. In LPS-sensitized HI groups, both OPN and GFAP were significantly increased either in LPS-mild-HI or LPS-severe-HI groups compared with the naïve group (all p < 0.05). Induced inflammation by LPS exaggerated neonatal HI brain injury. The plasma OPN and GFAP levels may be useful to differentiate HI alone groups from inflammation-sensitized HI groups or naïve group.
- Published
- 2020
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21. Magnetotransport studies of Fe vacancy-ordered Fe 4+δ Se 5 nanowires.
- Author
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Yeh KY, Lo TS, Wu PM, Chang-Liao KS, Wang MJ, and Wu MK
- Abstract
We studied the electrical transport of Fe
4+δ Se5 single-crystal nanowires exhibiting √5 × √5 Fe-vacancy order and mixed valence of Fe. Fe4+δ Se5 compound has been identified as the parent phase of FeSe superconductor. A first-order metal-insulator (MI) transition of transition temperature TMI ∼ 28 K is observed at zero magnetic fields ( B ). Colossal positive magnetoresistance emerges, resulting from the magnetic field-dependent MI transition. TMI demonstrates anisotropic magnetic field dependence with the preferred orientation along the c axis. At temperature T < ∼17 K, the state of near-magnetic field-independent resistance, which is due to spin polarized even at zero fields, preserves under magnetic fields up to B = 9 T. The Arrhenius law shift of the transition on the source-drain frequency dependence reveals that it is a nonoxide compound with the Verwey-like electronic correlation. The observation of the magnetic field-independent magnetoresistance at low temperature suggests it is in a charge-ordered state below T ∼ 17 K. The results of the field orientation measurements indicate that the spin-orbital coupling is crucial in √5 × √5 Fe vacancy-ordered Fe4+δ Se5 at low temperatures. Our findings provide valuable information to better understand the orbital nature and the interplay between the MI transition and superconductivity in FeSe-based materials., Competing Interests: The authors declare no competing interest., (Copyright © 2020 the Author(s). Published by PNAS.)- Published
- 2020
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22. Volumetric modulated arc therapy (VMAT) for hippocampal-avoidance whole brain radiation therapy: planning comparison with Dual-arc and Split-arc partial-field techniques.
- Author
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Yuen AHL, Wu PM, Li AKL, and Mak PCY
- Subjects
- Brain Neoplasms diagnostic imaging, Hippocampus diagnostic imaging, Humans, Image Processing, Computer-Assisted methods, Quality Assurance, Health Care standards, Radiotherapy Dosage, Radiotherapy Planning, Computer-Assisted methods, Tomography, X-Ray Computed methods, Brain Neoplasms radiotherapy, Cranial Irradiation methods, Hippocampus radiation effects, Organ Sparing Treatments methods, Organs at Risk radiation effects, Radiotherapy Planning, Computer-Assisted standards, Radiotherapy, Intensity-Modulated methods
- Abstract
Background: Although whole brain radiation therapy (WBRT) provides palliation and prophylaxis, reduces local recurrence probability and improves overall survival, it is evident that WBRT is associated with neurocognitive deficits due to radiation induced damage of the hippocampus. Therefore, minimizing hippocampal dose to the least possible level is of high clinical relevance. In dual-arc conventional volumetric modulated arc therapy (dac-VMAT), the large irradiation field for whole brain planned target volume (PTV) requires a wide jaw opening in which substantial low dose volume to the hippocampus may be produced due to suboptimal multi-leaf collimator (MLC) movements. The present study investigates the potential of a radiation therapy technique with split-arc and reduced field size, namely split-arc partial-field volumetric modulated arc therapy (sapf-VMAT) to spare the hippocampus during WBRT., Methods: Computed tomography and magnetic resonance images of 20 patients with brain metastases were retrieved in this retrospective planning study. The hippocampus was manually delineated by single radiation oncologist strictly following the RTOG 0933 atlas definition. Plans delivering 30 Gy in 10 fractions were generated for each patient using dac-VMAT and sapf-VMAT. Dosimetric parameters from both techniques were compared by paired t-test., Results: The results demonstrated that radiation dose to the hippocampus was significantly reduced using sapf-VMAT relative to dac-VMAT plans. sapf-VMAT (7.86Gy, p = 0.001) had significantly lowered average D
100% compared to dac-VMAT (9.23 Gy). Decrease in hippocampus Dmax using sapf-VMAT (13.23 Gy, p = 0.001) was statistically significant when compared to dac-VMAT (16.33 Gy). The resulting mean dose to the hippocampus was 9.16 Gy for the for sapf-VMAT. Mean dose of sapf-VMAT was significantly lower than dac-VMAT (10.85 Gy, p < 0.05). In both eyes, sapf-VMAT demonstrated significantly lower Dmean compared to dac-VMAT (p < 0.05). Whole brain PTV coverage was not compromised in both techniques., Conclusion: sapf-VMAT has demonstrated significant dose reduction to the hippocampus and both eyes compared to dac-VMAT.- Published
- 2020
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23. Epilepsy occurrence after neonatal morbidities in very preterm infants.
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Tu YF, Wang ST, Shih HI, Wu PM, Yu WH, and Huang CC
- Subjects
- Child, Preschool, Female, Humans, Incidence, Infant, Infant, Newborn, Infant, Newborn, Diseases, Male, Taiwan epidemiology, Epilepsy epidemiology, Infant, Premature
- Abstract
Objective: This study investigated the incidence of epilepsy and identified neonatal risk morbidities for epilepsy in children born extremely preterm., Methods: Of the 806 very preterm infants (birth weight < 1500 g, gestational age < 32 weeks) who survived and were discharged from the four neonatal intensive care units in southern Taiwan between 2003 and 2012, 686 (85.1%) had longitudinal neurodevelopmental follow-up assessments up to 5 years of age., Results: Among the 686 very preterm children, 19 (2.8%) exhibited epilepsy at a mean age of 19 ± 14 months. The incidence of epilepsy was highest among infants with neonatal seizure (33%), followed by cystic periventricular leukomalacia (cPVL, 27%), high-grade intraventricular hemorrhage (IVH, 21%), and necrotizing enterocolitis (NEC) stage III (20%). NEC stage III, neonatal seizure, high-grade IVH, and cPVL were also independent neonatal risk morbidities for epilepsy. Furthermore, the incidence of epilepsy was 21.6% in preterm children with significant neonatal brain injury (SNBI; ie, high-grade IVH and cPVL), but only 1% in preterm children without SNBI. Among preterm children with SNBI, neonatal seizure was higher in preterm children with epilepsy than in those without epilepsy (23.1% vs 2.1%, P = .03). Among preterm children without SNBI, NEC stage III was higher in preterm children with epilepsy than in those without epilepsy (33.3% vs 1.8%, P < .01). The preterm children with epilepsy were prone to have neurodevelopmental disability regardless of whether they had neonatal brain injury, and drug-resistant epilepsy (42%), particularly those with neonatal high-grade IVH., Significance: There is an elevated incidence of epilepsy among very preterm children, and particularly those with significant brain injury and/or severe NEC during the neonatal period. Very preterm children with epilepsy are prone to have neurodevelopmental disability and drug-resistant epilepsy., (Wiley Periodicals, Inc. © 2019 International League Against Epilepsy.)
- Published
- 2019
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24. Corpus callosum and cerebellar vermis size in very preterm infants: Relationship to long-term neurodevelopmental outcome.
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Wu PM, Shih HI, Yu WH, Chen LW, Wang LC, Huang CC, and Tu YF
- Subjects
- Cerebral Palsy pathology, Child, Preschool, Cohort Studies, Female, Gestational Age, Humans, Infant, Infant, Newborn, Infant, Very Low Birth Weight, Intellectual Disability pathology, Male, Brain growth & development, Cerebellar Vermis anatomy & histology, Corpus Callosum anatomy & histology, Infant, Premature growth & development
- Abstract
Background: The neonatal changes of corpus callosum or cerebellar volume in preterm infants have been shown to link with abnormal mentality and motor disability in early childhood. This study aims to predict the long-term neurological outcomes by measuring these changes on neonatal brain ultrasound in preterm infants., Methods: Our cohort consisted of infants aged below 32 weeks' gestation with very low birth body weights who completed neuro-assessments at 5 years of age. Corpus callosum or cerebellar vermis were measured at 28-30 weeks and at 37-40 weeks gestational age in premature infants with cerebral palsy (CP), mental retardation (MR) and normal control premature infants., Results: There are 12 patients in MR group, 12 in CP group and 27 patients as controls for final analysis. There was no significant difference in other factors between study groups except lower gestational age (P = 0.043) in CP group. Respiratory distress syndrome was more common in MR group (P = 0.037) and cystic periventricular leukomalacia was more common in CP group (P < 0.001) than controls. After adjusting for sex and birth body weight, the MR group had smaller cerebellar vermis area at 37-40 gestational weeks (P = 0.002) than controls. They also reduced the growth of corpus callosum area (difference = -0.12 ± 0.16, P = 0.029) and cerebellar vermis area (difference = 1.10 ± 0.44, P = 0.020) from 28 to 30 gestational weeks to 37-40 gestational weeks compared with controls (difference = 0.03 ± 0.15, 1.92 ± 0.70, respectively). In contrast, the CP group had reduced the growth of corpus callosum body (difference = -0.02 ± 0.18, P = 0.034) compared with controls (difference = 0.03 ± 0.04). They subsequently had smaller body thickness of corpus callosum (0.10 ± 0.02, P = 0.015) at 37-40 gestational weeks than controls (0.14 ± 0.04)., Conclusions: Serial monitoring corpus callosum and cerebellar vermis size in early life of very preterm babies may predict the motor or mentality neurological outcome at 5 years of age., (Copyright © 2018. Published by Elsevier B.V.)
- Published
- 2019
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25. Fully Automated Delineation of Gross Tumor Volume for Head and Neck Cancer on PET-CT Using Deep Learning: A Dual-Center Study.
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Huang B, Chen Z, Wu PM, Ye Y, Feng ST, Wong CO, Zheng L, Liu Y, Wang T, Li Q, and Huang B
- Subjects
- Female, Humans, Male, Middle Aged, Deep Learning, Head and Neck Neoplasms diagnostic imaging, Models, Theoretical, Positron Emission Tomography Computed Tomography
- Abstract
Purpose: In this study, we proposed an automated deep learning (DL) method for head and neck cancer (HNC) gross tumor volume (GTV) contouring on positron emission tomography-computed tomography (PET-CT) images., Materials and Methods: PET-CT images were collected from 22 newly diagnosed HNC patients, of whom 17 (Database 1) and 5 (Database 2) were from two centers, respectively. An oncologist and a radiologist decided the gold standard of GTV manually by consensus. We developed a deep convolutional neural network (DCNN) and trained the network based on the two-dimensional PET-CT images and the gold standard of GTV in the training dataset. We did two experiments: Experiment 1, with Database 1 only, and Experiment 2, with both Databases 1 and 2. In both Experiment 1 and Experiment 2, we evaluated the proposed method using a leave-one-out cross-validation strategy. We compared the median results in Experiment 2 (GTVa) with the performance of other methods in the literature and with the gold standard (GTVm)., Results: A tumor segmentation task for a patient on coregistered PET-CT images took less than one minute. The dice similarity coefficient (DSC) of the proposed method in Experiment 1 and Experiment 2 was 0.481∼0.872 and 0.482∼0.868, respectively. The DSC of GTVa was better than that in previous studies. A high correlation was found between GTVa and GTVm ( R = 0.99, P < 0.001). The median volume difference (%) between GTVm and GTVa was 10.9%. The median values of DSC, sensitivity, and precision of GTVa were 0.785, 0.764, and 0.789, respectively., Conclusion: A fully automatic GTV contouring method for HNC based on DCNN and PET-CT from dual centers has been successfully proposed with high accuracy and efficiency. Our proposed method is of help to the clinicians in HNC management.
- Published
- 2018
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26. Mode Dependency of Quantum Decoherence Studied via an Aharonov-Bohm Interferometer.
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Lo TS, Lin Y, Wu PM, Ling DC, Chi CC, and Chen JC
- Abstract
We investigate the dependence of decoherence on the mode number M in a multiple-mode Aharonov-Bohm (AB) interferometer. The design of the AB interferometer allows us to precisely determine M by the additivity rule of ballistic conductors; meanwhile, the decoherence rate is simultaneously deduced by the variance of the AB oscillation amplitude. The AB amplitude decreases and fluctuates with depopulating M. Moreover, the normalized amplitude exhibits a maximum at a specific M (∼9). Data analysis reveals that the charge-fluctuation-induced dephasing, which depends on the geometry and the charge relaxation resistance of the system, could play an essential role in the decoherence process. Our results suggest that the phase coherence, in principle, can be optimized using a deliberated design and pave one of the ways toward the engineering of quantum coherence.
- Published
- 2016
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27. Evaluation of microelectrode materials for direct-current electrocorticography.
- Author
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Li C, Narayan RK, Wu PM, Rajan N, Wu Z, Mehan N, Golanov EV, Ahn CH, and Hartings JA
- Subjects
- Animals, Electric Conductivity, Equipment Design, Equipment Failure Analysis, Feasibility Studies, Male, Materials Testing, Rats, Rats, Sprague-Dawley, Signal-To-Noise Ratio, Biocompatible Materials chemistry, Cerebral Cortex physiology, Electrocorticography instrumentation, Electrodes, Implanted, Metals chemistry, Microelectrodes
- Abstract
Objective: Direct-current electrocorticography (DC-ECoG) allows a more complete characterization of brain states and pathologies than traditional alternating-current recordings (AC-ECoG). However, reliable recording of DC signals is challenging because of electrode polarization-induced potential drift, particularly at low frequencies and for more conducting materials. Further challenges arise as electrode size decreases, since impedance is increased and the potential drift is augmented. While microelectrodes have been investigated for AC-ECoG recordings, little work has addressed microelectrode properties for DC-signal recording. In this paper, we investigated several common microelectrode materials used in biomedical application for DC-ECoG., Approach: Five of the most common materials including gold (Au), silver/silver chloride (Ag/AgCl), platinum (Pt), Iridium oxide (IrOx), and platinum-iridium oxide (Pt/IrOx) were investigated for electrode diameters of 300 μm. The critical characteristics such as polarization impedance, AC current-induced polarization, long-term stability and low-frequency noise were studied in vitro (0.9% saline). The two most promising materials, Pt and Pt/lrOx were further investigated in vivo by recording waves of spreading depolarization, one of the most important applications for DC-ECoG in clinical and basic science research., Main Results: Our experimental results indicate that IrOx-based microelectrodes, particularly with composite layers of nanostructures, are excellent in all of the common evaluation characteristics both in vitro and in vivo and are most suitable for multimodal monitoring applications. Pt electrodes suffer high current-induced polarization, but have acceptable long-term stability suitable for DC-ECoG. Major significance. The results of this study provide quantitative data on the electrical properties of microelectrodes with commonly-used materials and will be valuable for development of neural recordings inclusive of low frequencies.
- Published
- 2016
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28. Mobile metallic domain walls in an all-in-all-out magnetic insulator.
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Ma EY, Cui YT, Ueda K, Tang S, Chen K, Tamura N, Wu PM, Fujioka J, Tokura Y, and Shen ZX
- Abstract
Magnetic domain walls are boundaries between regions with different configurations of the same magnetic order. In a magnetic insulator, where the magnetic order is tied to its bulk insulating property, it has been postulated that electrical properties are drastically different along the domain walls, where the order is inevitably disturbed. Here we report the discovery of highly conductive magnetic domain walls in a magnetic insulator, Nd2Ir2O7, that has an unusual all-in-all-out magnetic order, via transport and spatially resolved microwave impedance microscopy. The domain walls have a virtually temperature-independent sheet resistance of ~1 kilohm per square, show smooth morphology with no preferred orientation, are free from pinning by disorders, and have strong thermal and magnetic field responses that agree with expectations for all-in-all-out magnetic order., (Copyright © 2015, American Association for the Advancement of Science.)
- Published
- 2015
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29. Highly accurate thermal flow microsensor for continuous and quantitative measurement of cerebral blood flow.
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Li C, Wu PM, Wu Z, Limnuson K, Mehan N, Mozayan C, Golanov EV, Ahn CH, Hartings JA, and Narayan RK
- Subjects
- Animals, Computer-Aided Design, Equipment Design, Equipment Failure Analysis, Heating instrumentation, Male, Miniaturization, Rats, Rats, Sprague-Dawley, Reproducibility of Results, Sensitivity and Specificity, Blood Flow Velocity physiology, Cerebrovascular Circulation physiology, Conductometry instrumentation, Rheology instrumentation, Thermography instrumentation, Transducers
- Abstract
Cerebral blood flow (CBF) plays a critical role in the exchange of nutrients and metabolites at the capillary level and is tightly regulated to meet the metabolic demands of the brain. After major brain injuries, CBF normally decreases and supporting the injured brain with adequate CBF is a mainstay of therapy after traumatic brain injury. Quantitative and localized measurement of CBF is therefore critically important for evaluation of treatment efficacy and also for understanding of cerebral pathophysiology. We present here an improved thermal flow microsensor and its operation which provides higher accuracy compared to existing devices. The flow microsensor consists of three components, two stacked-up thin film resistive elements serving as composite heater/temperature sensor and one remote resistive element for environmental temperature compensation. It operates in constant-temperature mode (~2 °C above the medium temperature) providing 20 ms temporal resolution. Compared to previous thermal flow microsensor based on self-heating and self-sensing design, the sensor presented provides at least two-fold improvement in accuracy in the range from 0 to 200 ml/100 g/min. This is mainly achieved by using the stacked-up structure, where the heating and sensing are separated to improve the temperature measurement accuracy by minimization of errors introduced by self-heating.
- Published
- 2015
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30. Microstructural brain abnormalities of children of idiopathic generalized epilepsy with generalized tonic-clonic seizure: a voxel-based diffusional kurtosis imaging study.
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Gao J, Feng ST, Wu B, Gong N, Lu M, Wu PM, Wang H, He X, and Huang B
- Subjects
- Child, Female, Humans, Imaging, Three-Dimensional methods, Male, Brain pathology, Diffusion Magnetic Resonance Imaging methods, Epilepsy, Generalized pathology, Epilepsy, Tonic-Clonic pathology
- Abstract
Purpose: To investigate the diffusion abnormalities in the brain of children with idiopathic generalized epilepsy (IGE) with generalized tonic-clonic seizure (GTCS) by using diffusion kurtosis imaging (DKI)., Materials and Methods: Twenty-one IGE children with GTCS and 16 controls were recruited. DKI was performed and maps of radial diffusivity (λ⊥ ), axial diffusivity (λ// ), mean diffusivity (MD), fractional anisotropy (FA), radial kurtosis (K⊥ ), axial kurtosis (K// ) and mean kurtosis (MK) were calculated. Voxel-based analyses were employed to compare diffusion metrics in epilepsy versus the controls., Results: In the case group, MD was found significantly higher in the right temporal lobe, the right occipital lobe, hippocampus, and some subcortical regions, while FA increased in bilateral supplementary motor area and the left superior frontal lobe (false discovery rate corrected P < 0.05). Analysis of λ⊥ and λ// showed that the increased MD was mainly due to the elevated λ// . Significantly decreased MK was also detected in bilateral temporo-occipital regions, the right hippocampus, the left insula, the left post-central area, and some subcortical regions (false discovery rate corrected P < 0.05). In most regions the changed MK were due to the decreased K// ., Conclusion: The kurtosis parameters (K⊥ , K// , and MK) reflect different microstructural information in the IGE children with GTCS, and this support the value of DKI in studying children GTCS., (© 2014 Wiley Periodicals, Inc.)
- Published
- 2015
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31. Targeting miR-155 restores abnormal microglia and attenuates disease in SOD1 mice.
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Butovsky O, Jedrychowski MP, Cialic R, Krasemann S, Murugaiyan G, Fanek Z, Greco DJ, Wu PM, Doykan CE, Kiner O, Lawson RJ, Frosch MP, Pochet N, Fatimy RE, Krichevsky AM, Gygi SP, Lassmann H, Berry J, Cudkowicz ME, and Weiner HL
- Subjects
- Aged, Amyotrophic Lateral Sclerosis drug therapy, Amyotrophic Lateral Sclerosis metabolism, Animals, Apolipoproteins E pharmacology, Apolipoproteins E therapeutic use, Cells, Cultured, Disease Models, Animal, Female, Gene Expression Regulation drug effects, Hippocampus cytology, Humans, Male, Mice, Mice, Transgenic, MicroRNAs chemistry, MicroRNAs genetics, Microglia drug effects, Microglia metabolism, Middle Aged, Monocytes drug effects, Monocytes metabolism, Neurons drug effects, Neurons metabolism, Oligoribonucleotides, Antisense therapeutic use, Phagocytosis drug effects, Phagocytosis genetics, Transforming Growth Factor beta genetics, Transforming Growth Factor beta metabolism, Amyotrophic Lateral Sclerosis genetics, Amyotrophic Lateral Sclerosis pathology, Gene Expression Regulation genetics, MicroRNAs metabolism, Spinal Cord pathology, Superoxide Dismutase genetics
- Abstract
Objective: To investigate miR-155 in the SOD1 mouse model and human sporadic and familial amyotrophic lateral sclerosis (ALS)., Methods: NanoString microRNA, microglia and immune gene profiles, protein mass spectrometry, and RNA-seq analyses were measured in spinal cord microglia, splenic monocytes, and spinal cord tissue from SOD1 mice and in spinal cord tissue of familial and sporadic ALS. miR-155 was targeted by genetic ablation or by peripheral or centrally administered anti-miR-155 inhibitor in SOD1 mice., Results: In SOD1 mice, we found loss of the molecular signature that characterizes homeostatic microglia and increased expression of miR-155. There was loss of the microglial molecules P2ry12, Tmem119, Olfml3, transcription factors Egr1, Atf3, Jun, Fos, and Mafb, and the upstream regulators Csf1r, Tgfb1, and Tgfbr1, which are essential for microglial survival. Microglia biological functions were suppressed including phagocytosis. Genetic ablation of miR-155 increased survival in SOD1 mice by 51 days in females and 27 days in males and restored the abnormal microglia and monocyte molecular signatures. Disease severity in SOD1 males was associated with early upregulation of inflammatory genes, including Apoe in microglia. Treatment of adult microglia with apolipoprotein E suppressed the M0-homeostatic unique microglia signature and induced an M1-like phenotype. miR-155 expression was increased in the spinal cord of both familial and sporadic ALS. Dysregulated proteins that we identified in human ALS spinal cord were restored in SOD1(G93A) /miR-155(-/-) mice. Intraventricular anti-miR-155 treatment derepressed microglial miR-155 targeted genes, and peripheral anti-miR-155 treatment prolonged survival., Interpretation: We found overexpression of miR-155 in the SOD1 mouse and in both sporadic and familial human ALS. Targeting miR-155 in SOD1 mice restores dysfunctional microglia and ameliorates disease. These findings identify miR-155 as a therapeutic target for the treatment of ALS., (© 2014 American Neurological Association.)
- Published
- 2015
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32. Crystal phase-dependent nanophotonic resonances in InAs nanowire arrays.
- Author
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Anttu N, Lehmann S, Storm K, Dick KA, Samuelson L, Wu PM, and Pistol ME
- Abstract
Nanostructures have many material, electronic, and optical properties that are not found in bulk systems and that are relevant for technological applications. For example, nanowires realized from III-V semiconductors can be grown into a wurtzite crystal structure. This crystal structure does not naturally exist in bulk where these materials form the zinc-blende counterpart. Being able to concomitantly grow these nanowires in the zinc-blende and/or wurtzite crystal structure provides an important degree of control for the design and optimization of optoelectronic applications based on these semiconductor nanostructures. However, the refractive indices of this new crystallographic phase have so far not been elucidated. This shortcoming makes it impossible to predict and utilize the full potential of these new nanostructured materials for optoelectronics applications: a careful design and optimization of optical resonances by tuning the nanostructure geometry is needed to achieve optimal performance. Here, we report and analyze striking differences in the optical response of nanophotonic resonances in wurtzite and zinc-blende InAs nanowire arrays. Specifically, through reflectance measurements we find that the resonance can be tuned down to λ ≈ 380 nm in wurtzite nanowires by decreasing the nanowire diameter. In stark contrast, a similar tuning to below λ ≈ 500 nm is not possible in the zinc-blende nanowires. Furthermore, we find that the wurtzite nanowires can absorb twice as strongly as the zinc-blende nanowires. We attribute these strikingly large differences in resonant behavior to large differences between the refractive indices of the two crystallographic phases realized in these nanostructures. We anticipate our findings to be relevant for other III-V materials as well as for all material systems that manifest polytypism. Taken together, our results demonstrate crystal phase engineering as a potentially new design dimension for optoelectronics applications.
- Published
- 2014
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33. Differential roles of microglia and monocytes in the inflamed central nervous system.
- Author
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Yamasaki R, Lu H, Butovsky O, Ohno N, Rietsch AM, Cialic R, Wu PM, Doykan CE, Lin J, Cotleur AC, Kidd G, Zorlu MM, Sun N, Hu W, Liu L, Lee JC, Taylor SE, Uehlein L, Dixon D, Gu J, Floruta CM, Zhu M, Charo IF, Weiner HL, and Ransohoff RM
- Subjects
- Animals, CX3C Chemokine Receptor 1, Cell Shape, Encephalomyelitis, Autoimmune, Experimental genetics, Encephalomyelitis, Autoimmune, Experimental pathology, Gene Expression Profiling, Gene Expression Regulation, Gene Regulatory Networks, Homeostasis genetics, Humans, Inflammation genetics, Kinetics, Macrophages pathology, Mice, Mice, Inbred C57BL, Microglia ultrastructure, Monocytes ultrastructure, Ranvier's Nodes pathology, Receptors, CCR2 metabolism, Receptors, Chemokine metabolism, Signal Transduction genetics, Time Factors, Central Nervous System pathology, Inflammation pathology, Microglia pathology, Monocytes pathology
- Abstract
In the human disorder multiple sclerosis (MS) and in the model experimental autoimmune encephalomyelitis (EAE), macrophages predominate in demyelinated areas and their numbers correlate to tissue damage. Macrophages may be derived from infiltrating monocytes or resident microglia, yet are indistinguishable by light microscopy and surface phenotype. It is axiomatic that T cell-mediated macrophage activation is critical for inflammatory demyelination in EAE, yet the precise details by which tissue injury takes place remain poorly understood. In the present study, we addressed the cellular basis of autoimmune demyelination by discriminating microglial versus monocyte origins of effector macrophages. Using serial block-face scanning electron microscopy (SBF-SEM), we show that monocyte-derived macrophages associate with nodes of Ranvier and initiate demyelination, whereas microglia appear to clear debris. Gene expression profiles confirm that monocyte-derived macrophages are highly phagocytic and inflammatory, whereas those arising from microglia demonstrate an unexpected signature of globally suppressed cellular metabolism at disease onset. Distinguishing tissue-resident macrophages from infiltrating monocytes will point toward new strategies to treat disease and promote repair in diverse inflammatory pathologies in varied organs., (© 2014 Yamsaki et al.)
- Published
- 2014
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34. Identification of a unique TGF-β-dependent molecular and functional signature in microglia.
- Author
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Butovsky O, Jedrychowski MP, Moore CS, Cialic R, Lanser AJ, Gabriely G, Koeglsperger T, Dake B, Wu PM, Doykan CE, Fanek Z, Liu L, Chen Z, Rothstein JD, Ransohoff RM, Gygi SP, Antel JP, and Weiner HL
- Subjects
- Analysis of Variance, Animals, Animals, Newborn, Antigens, CD metabolism, Cells, Cultured, Chromatography, Ion Exchange, Embryo, Mammalian, Female, Flow Cytometry, Gene Expression Regulation, Developmental physiology, Humans, Male, Mass Spectrometry, Mice, Mice, Inbred C57BL, Mice, Transgenic, MicroRNAs genetics, Microglia classification, Neurons metabolism, Receptors, Purinergic P2Y12 metabolism, Tissue Array Analysis, Transforming Growth Factor beta1 genetics, Central Nervous System cytology, Microglia metabolism, Signal Transduction genetics, Transforming Growth Factor beta1 metabolism
- Abstract
Microglia are myeloid cells of the CNS that participate both in normal CNS function and in disease. We investigated the molecular signature of microglia and identified 239 genes and 8 microRNAs that were uniquely or highly expressed in microglia versus myeloid and other immune cells. Of the 239 genes, 106 were enriched in microglia as compared with astrocytes, oligodendrocytes and neurons. This microglia signature was not observed in microglial lines or in monocytes recruited to the CNS, and was also observed in human microglia. We found that TGF-β was required for the in vitro development of microglia that express the microglial molecular signature characteristic of adult microglia and that microglia were absent in the CNS of TGF-β1-deficient mice. Our results identify a unique microglial signature that is dependent on TGF-β signaling and provide insights into microglial biology and the possibility of targeting microglia for the treatment of CNS disease.
- Published
- 2014
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35. Large thermoelectric power factor enhancement observed in InAs nanowires.
- Author
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Wu PM, Gooth J, Zianni X, Svensson SF, Gluschke JG, Dick KA, Thelander C, Nielsch K, and Linke H
- Abstract
We report the observation of a thermoelectric power factor in InAs nanowires that exceeds that predicted by a single-band bulk model by up to an order of magnitude at temperatures below about 20 K. We attribute this enhancement effect not to the long-predicted 1D subband effects but to quantum-dot-like states that form in electrostatically nonuniform nanowires as a result of interference between propagating states and 0D resonances.
- Published
- 2013
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36. Diffusion abnormalities in temporal lobes of children with temporal lobe epilepsy: a preliminary diffusional kurtosis imaging study and comparison with diffusion tensor imaging.
- Author
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Gao Y, Zhang Y, Wong CS, Wu PM, Zhang Z, Gao J, Qiu D, and Huang B
- Subjects
- Case-Control Studies, Child, Diffusion, Electroencephalography, Female, Humans, Male, Diffusion Tensor Imaging methods, Epilepsy, Temporal Lobe physiopathology, Temporal Lobe physiopathology
- Abstract
In this preliminary study, we aimed to investigate the abnormalities of water diffusion in children with temporal lobe epilepsy (TLE). Eight children with unilateral TLE (according to electroencephalography, EEG) and eight age- and sex-matched controls were recruited. Diffusion tensor imaging (DTI)/diffusional kurtosis imaging (DKI) acquisitions were performed. Radial diffusivity (λ(⊥)), axial diffusivity (λ(∥)), mean diffusivity (MD) and fractional anisotropy (FA) maps were calculated for both DTI and DKI, and radial kurtosis (K(⊥)), axial kurtosis (K(∥)) and mean kurtosis (MK) maps were calculated for DKI only. Mann-Whitney test showed that, for white matter in the temporal lobe, DKI-derived λ(∥) , MD and K(∥) were significantly different in bilateral temporal lobes and EEG-abnormal and EEG-normal sides of the temporal lobe between patients and controls, whereas DTI showed no abnormalities. For gray matter, DKI detected significantly higher MD and MK in the same three comparisons, whereas DTI detected abnormalities only in the comparison between bilateral temporal lobes and between EEG-normal sides in cases and left-right matched sides in controls. No significant difference was observed between EEG-abnormal and EEG-normal sides in cases. These preliminary results indicate that DKI is more sensitive than DTI for the detection of diffusion abnormalities in the temporal lobes of children with TLE, even when EEG signals are normal. These findings pave the way for the application of DKI for in-depth studies on TLE in children., (Copyright © 2012 John Wiley & Sons, Ltd.)
- Published
- 2012
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37. Spatially resolved Hall effect measurement in a single semiconductor nanowire.
- Author
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Storm K, Halvardsson F, Heurlin M, Lindgren D, Gustafsson A, Wu PM, Monemar B, and Samuelson L
- Subjects
- Electric Conductivity, Electrodes, Electronics instrumentation, Equipment Design, Magnetic Fields, Nanowires ultrastructure, Nanowires chemistry, Semiconductors
- Abstract
Efficient light-emitting diodes and photovoltaic energy-harvesting devices are expected to play an important role in the continued efforts towards sustainable global power consumption. Semiconductor nanowires are promising candidates as the active components of both light-emitting diodes and photovoltaic cells, primarily due to the added freedom in device design offered by the nanowire geometry. However, for nanowire-based components to move past the proof-of-concept stage and be implemented in production-grade devices, it is necessary to precisely quantify and control fundamental material properties such as doping and carrier mobility. Unfortunately, the nanoscale geometry that makes nanowires interesting for applications also makes them inherently difficult to characterize. Here, we report a method to carry out Hall measurements on single core-shell nanowires. Our technique allows spatially resolved and quantitative determination of the carrier concentration and mobility of the nanowire shell. As Hall measurements have previously been completely unavailable for nanowires, the experimental platform presented here should facilitate the implementation of nanowires in advanced practical devices.
- Published
- 2012
- Full Text
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38. Modulating inflammatory monocytes with a unique microRNA gene signature ameliorates murine ALS.
- Author
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Butovsky O, Siddiqui S, Gabriely G, Lanser AJ, Dake B, Murugaiyan G, Doykan CE, Wu PM, Gali RR, Iyer LK, Lawson R, Berry J, Krichevsky AM, Cudkowicz ME, and Weiner HL
- Subjects
- Amyotrophic Lateral Sclerosis drug therapy, Amyotrophic Lateral Sclerosis genetics, Amyotrophic Lateral Sclerosis pathology, Animals, Antibodies, Monoclonal administration & dosage, Antigens, CD genetics, Antigens, CD metabolism, Antigens, Ly genetics, Antigens, Ly immunology, Antigens, Ly metabolism, Apoptosis, Apyrase genetics, Apyrase metabolism, Cell Proliferation, Chemotaxis, Female, Gene Regulatory Networks, Humans, Inflammation Mediators metabolism, Macrophages, Alveolar metabolism, Male, Metabolic Networks and Pathways, Mice, Mice, Inbred C57BL, Mice, Transgenic, MicroRNAs metabolism, Microglia immunology, Microglia pathology, Monocytes metabolism, Monocytes pathology, Oligonucleotide Array Sequence Analysis, RNA Interference, Rats, Rats, Inbred Lew, Spinal Cord pathology, Spleen immunology, Spleen pathology, Superoxide Dismutase genetics, Superoxide Dismutase-1, Transcription Factors genetics, Transcription Factors metabolism, Transcriptome, Amyotrophic Lateral Sclerosis immunology, Immunomodulation, MicroRNAs genetics, Monocytes immunology, Spinal Cord immunology
- Abstract
Amyotrophic lateral sclerosis (ALS) is a progressive disease associated with neuronal cell death that is thought to involve aberrant immune responses. Here we investigated the role of innate immunity in a mouse model of ALS. We found that inflammatory monocytes were activated and that their progressive recruitment to the spinal cord, but not brain, correlated with neuronal loss. We also found a decrease in resident microglia in the spinal cord with disease progression. Prior to disease onset, splenic Ly6Chi monocytes expressed a polarized macrophage phenotype (M1 signature), which included increased levels of chemokine receptor CCR2. As disease onset neared, microglia expressed increased CCL2 and other chemotaxis-associated molecules, which led to the recruitment of monocytes to the CNS by spinal cord-derived microglia. Treatment with anti-Ly6C mAb modulated the Ly6Chi monocyte cytokine profile, reduced monocyte recruitment to the spinal cord, diminished neuronal loss, and extended survival. In humans with ALS, the analogous monocytes (CD14+CD16-) exhibited an ALS-specific microRNA inflammatory signature similar to that observed in the ALS mouse model, linking the animal model and the human disease. Thus, the profile of monocytes in ALS patients may serve as a biomarker for disease stage or progression. Our results suggest that recruitment of inflammatory monocytes plays an important role in disease progression and that modulation of these cells is a potential therapeutic approach.
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- 2012
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39. Micromachined lab-on-a-tube sensors for simultaneous brain temperature and cerebral blood flow measurements.
- Author
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Li C, Wu PM, Hartings JA, Wu Z, Cheyuo C, Wang P, LeDoux D, Shutter LA, Ramaswamy BR, Ahn CH, and Narayan RK
- Subjects
- Time Factors, Brain blood supply, Cerebrovascular Circulation, Microtechnology instrumentation, Temperature
- Abstract
This work describes the development of a micromachined lab-on-a-tube device for simultaneous measurement of brain temperature and regional cerebral blood flow. The device consists of two micromachined gold resistance temperature detectors with a 4-wire configuration. One is used as a temperature sensor and the other as a flow sensor. The temperature sensor operates with AC excitation current of 500 μA and updates its outputs at a rate of 5 Hz. The flow sensor employs a periodic heating and cooling technique under constant-temperature mode and updates its outputs at a rate of 0.1 Hz. The temperature sensor is also used to compensate for temperature changes during the heating period of the flow sensor to improve the accuracy of flow measurements. To prevent thermal and electronic crosstalk between the sensors, the temperature sensor is located outside the "thermal influence" region of the flow sensor and the sensors are separated into two different layers with a thin-film Copper shield. We evaluated the sensors for accuracy, crosstalk and long-term drift in human blood-stained cerebrospinal fluid. These in vitro experiments showed that simultaneous temperature and flow measurements with a single lab-on-a-tube device are accurate and reliable over the course of 5 days. It has a resolution of 0.013 °C and 0.18 ml/100 g/min; and achieves an accuracy of 0.1 °C and 5 ml/100 g/min for temperature and flow sensors respectively. The prototype device and techniques developed here establish a foundation for a multi-sensor lab-on-a-tube, enabling versatile multimodality monitoring applications.
- Published
- 2012
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40. Colorful InAs nanowire arrays: from strong to weak absorption with geometrical tuning.
- Author
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Wu PM, Anttu N, Xu HQ, Samuelson L, and Pistol ME
- Abstract
One-dimensional nanostructure arrays can show fascinatingly different, tunable optical response compared to bulk systems. Here we study theoretically and demonstrate experimentally how to engineer the reflection and absorption of light in epitaxially grown vertical arrays of InAs nanowires (NWs). A striking observation is optically visible colors of the array, which we show can be tuned depending on the geometrical parameters of the array. Specifically, larger diameter NW arrays absorb light more effectively out to a longer wavelength compared to smaller diameter arrays. Thus, controlling the diameter provides a way to tune the optically observable color of an array. We also find that arrays with a larger amount of InAs material reflect less light (or absorb more light) than arrays with less material. On the basis of these two trends, InAs NW arrays can be designed to absorb light either much more or much less efficiently than a thin film of an effective medium containing the same amount of InAs as the NW array. The tunable absorption and low area filling factor of the NW arrays compared to thin film bode well for III-V photovoltaics and photodetection., (© 2012 American Chemical Society)
- Published
- 2012
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41. Brain temperature measurement: A study of in vitro accuracy and stability of smart catheter temperature sensors.
- Author
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Li C, Wu PM, Wu Z, Ahn CH, LeDoux D, Shutter LA, Hartings JA, and Narayan RK
- Subjects
- Catheters, Humans, Signal-To-Noise Ratio, Body Temperature, Brain physiology, Thermometers
- Abstract
The injured brain is vulnerable to increases in temperature after severe head injury. Therefore, accurate and reliable measurement of brain temperature is important to optimize patient outcome. In this work, we have fabricated, optimized and characterized temperature sensors for use with a micromachined smart catheter for multimodal intracranial monitoring. Developed temperature sensors have resistance of 100.79 ± 1.19Ω and sensitivity of 67.95 mV/°C in the operating range from15-50°C, and time constant of 180 ms. Under the optimized excitation current of 500 μA, adequate signal-to-noise ratio was achieved without causing self-heating, and changes in immersion depth did not introduce clinically significant errors of measurements (<0.01°C). We evaluated the accuracy and long-term drift (5 days) of twenty temperature sensors in comparison to two types of commercial temperature probes (USB Reference Thermometer, NIST-traceable bulk probe with 0.05°C accuracy; and IT-21, type T type clinical microprobe with guaranteed 0.1°C accuracy) under controlled laboratory conditions. These in vitro experimental data showed that the temperature measurement performance of our sensors was accurate and reliable over the course of 5 days. The smart catheter temperature sensors provided accuracy and long-term stability comparable to those of commercial tissue-implantable microprobes, and therefore provide a means for temperature measurement in a microfabricated, multimodal cerebral monitoring device.
- Published
- 2012
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42. Brain-friendly amperometric enzyme biosensor based on encapsulated oxygen generating biomaterial.
- Author
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Li C, Wu Z, Hartings JA, Rajan N, Chahine N, Cheyuo C, Wang P, Wu PM, Golanov EV, Ahn CH, and Narayan RK
- Subjects
- Microelectrodes, Biocompatible Materials, Biosensing Techniques, Brain metabolism, Electrochemical Techniques, Enzymes, Immobilized metabolism, Glucose Oxidase metabolism, Oxygen metabolism
- Abstract
A novel first-generation Clark-type biosensor platform that can eliminate the oxygen dependence has been presented. Sufficient oxygen to drive the enzymatic reaction under hypoxic conditions was produced by encapsulated oxygen generating biomaterial, calcium peroxide. The catalase immobilized in chitosan matrix was coated on top of the groove to decompose residual hydrogen peroxide to oxygen. A glucose biosensor was developed on the proposed platform as proof of concept. Under hypoxic conditions, developed glucose biosensors maintained their sensitivity response around 84% of their response at oxygen tension of 151 mmHg. The sensitivity deviation was less than 5.3% with the oxygen tension traversed from 0 to 57 mmHg. Under oxygen tension of 8.3 mmHg, the sensitivity of 37.130 nA/mM and the linear coefficient of R(2)=0.9968 were obtained with the glucose concentration varying from 0.05 to 10mM. This new platform is particularly attractive for injured brain monitoring.
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- 2012
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43. Switching currents limited by single phase slips in one-dimensional superconducting Al nanowires.
- Author
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Li P, Wu PM, Bomze Y, Borzenets IV, Finkelstein G, and Chang AM
- Abstract
An aluminum nanowire switches from superconducting to normal as the current is increased in an upsweep. The switching current (I(s)) averaged over upsweeps approximately follows the depairing critical current (I(c)) but falls below it. Fluctuations in I(s) exhibit three distinct regions of behaviors and are nonmonotonic in temperature: saturation well below the critical temperature T(c), an increase as T(2/3) at intermediate temperatures, and a rapid decrease close to T(c). Heat dissipation analysis indicates that a single phase slip is able to trigger switching at low and intermediate temperatures, whereby the T(2/3) dependence arises from the thermal activation of a phase slip, while saturation at low temperatures provides striking evidence that the phase slips by macroscopic quantum tunneling.
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- 2011
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44. Potential of a simple lab-on-a-tube for point-of-care measurements of multiple analytes.
- Author
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Li C, Shutter LA, Wu PM, Ahn CH, and Narayan RK
- Subjects
- Equipment Design, Equipment Failure Analysis, Biosensing Techniques instrumentation, Complex Mixtures chemistry, Complex Mixtures isolation & purification, Microfluidic Analytical Techniques instrumentation, Point-of-Care Systems, Specimen Handling instrumentation
- Abstract
This technical note presents a simple and disposable lab-on-a-tube (LOT) for point-of-care measurements of multiple analytes. LOT is a one-step device that can perform both sample collection and multi-sensing on-site. Sample collection is conducted by taking advantage of its inherent micro/macro channel structure while multi-sensing is conducted by integrated microsensors. This approach ensures reliable transportation of various samples into the testing area by either passive capillary force or active suction force, thus avoiding the need for a pump or injection components as used in lab-on-a-chip systems. The developed LOT (Diameter = 1 mm, Sensing length = 4.5 mm, Required sample volume = 3.5 microl) is capable of simultaneously quantifying the concentrations of glucose, lactate and oxygen in human serum samples. The result suggests the LOT hold great potential for many point-of-care applications.
- Published
- 2010
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45. Crystal orientation and thickness dependence of the superconducting transition temperature of tetragonal FeSe1-x thin films.
- Author
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Wang MJ, Luo JY, Huang TW, Chang HH, Chen TK, Hsu FC, Wu CT, Wu PM, Chang AM, and Wu MK
- Abstract
Superconductivity was recently found in the tetragonal phase FeSe. A structural transformation from tetragonal to orthorhombic (or monoclinic, depending on point of view) was observed at low temperature, but was not accompanied by a magnetic ordering as commonly occurs in the parent compounds of FeAs-based superconductors. Here, we report the correlation between structural distortion and superconductivity in FeSe(1-x) thin films with different preferred growth orientations. The films with preferred growth along the c axis show a strong thickness dependent suppression of superconductivity and low temperature structural distortion. In contrast, both properties are less affected in the films with (101) preferred orientation. These results suggest that the low temperature structural distortion is closely associated with the superconductivity of this material.
- Published
- 2009
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46. A novel lab-on-a-tube for multimodality neuromonitoring of patients with traumatic brain injury (TBI).
- Author
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Li C, Wu PM, Jung W, Ahn CH, Shutter LA, and Narayan RK
- Subjects
- Biosensing Techniques, Brain Injuries blood, Brain Injuries cerebrospinal fluid, Humans, Monitoring, Physiologic instrumentation, Monitoring, Physiologic methods, Sensitivity and Specificity, Time Factors, Brain Injuries diagnosis, Brain Injuries physiopathology, Lab-On-A-Chip Devices, Microchip Analytical Procedures methods
- Abstract
A novel lab-on-a-tube integrated with spirally-rolled pressure, temperature, oxygen and glucose microsensors is described for multimodal neuromonitoring of patients with traumatic brain injury. In addition to measuring various crucial parameters in real-time continuous formats, the newly developed device also works as an intraventricular catheter to lower the elevated intracranial pressure by draining cerebrospinal fluid.
- Published
- 2009
- Full Text
- View/download PDF
47. High pressure superconductivity in iron-based layered compounds studied using designer diamonds.
- Author
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Tsoi G, Stemshorn AK, Vohra YK, Wu PM, Hsu FC, Huang YL, Wu MK, Yeh KW, and Weir ST
- Abstract
High pressure superconductivity in iron-based superconductor FeSe(0.5)Te(0.5) has been studied up to 15 GPa and 10 K using an eight probe designer diamond anvil in a diamond anvil cell device. Four probe electrical resistance measurements show the onset of superconductivity (T(c)) at 14 K at ambient pressure with T(c) increasing with increasing pressure to 19 K at a pressure of 3.6 GPa. At higher pressures beyond 3.6 GPa, T(c) decreases and extrapolation suggests non-superconducting behavior above 10 GPa. The loss of superconductivity coincides with the pressure induced disordering of the Fe(SeTe)(4) tetrahedra reported at 11 GPa in x-ray diffraction studies at ambient temperature.
- Published
- 2009
- Full Text
- View/download PDF
48. Development of a portable analyzer with polymer lab-on-a-chip (LOC) for continuous sampling and monitoring of Pb(II).
- Author
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Jang A, Zou Z, MacKnight E, Wu PM, Kim IS, Ahn CH, and Bishop PL
- Subjects
- Biosensing Techniques, Bismuth, Electrodes, Environmental Monitoring methods, Equipment Design, Lead, Microchemistry instrumentation, Microchemistry methods, Electrochemical Techniques instrumentation, Electrochemical Techniques methods, Environmental Monitoring instrumentation
- Abstract
A new portable analyzer with polymer lab-on-a-chip (LOC) has been designed, fabricated and fully characterized for continuous sampling and monitoring of lead (Pb(II)) in this work. As the working electrodes of the sensor, bismuth (Bi (III)) which allowed the advantage of being more environmentally friendly than traditional mercury drop electrodes was used, while maintaining similar sensitivity and other desirable characteristics. The size of a portable analyzer was 30 cmx23 cmx7 cm, and the weight was around 3 kg. The small size gives the advantage of being portable for field use while not sacrificing portability for accuracy of measurement. Furthermore, the autonomous system developed in coordination with the development of new polymer LOC integrated with electrochemical sensors can provide an innovative way to monitor surface waters in an efficient, cost-effective and sustainable manner.
- Published
- 2009
- Full Text
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49. A flexible polymer tube lab-chip integrated with microsensors for smart microcatheter.
- Author
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Li C, Wu PM, Han J, and Ahn CH
- Subjects
- Calibration, Cardiovascular Physiological Phenomena, Electrodes, Equipment Design instrumentation, Glucose analysis, Humans, Laboratories, Miniaturization instrumentation, Pliability, Temperature, Time Factors, Biosensing Techniques instrumentation, Catheterization instrumentation, Lab-On-A-Chip Devices, Microchemistry instrumentation, Polymers chemistry
- Abstract
A flexible polymer tube lab-chip integrated with physical and biochemical sensor modules mounted on a flexible spiral structure for measuring physiological (temperature/flow rate) and metabolic data (glucose concentration) in a catheter application was designed, fabricated and characterized in this work. This new approach not only provides a unique way to assemble multiple sensors on both the inside and outside the flexible polymer tube using standard microfabrication methods while avoiding wiring and assembling problems associated with previous methods, but also maintains catheter inherent lumen potency for in situ drug delivery or insertion of medical tools. Three well-known sensors: temperature sensor (RTD), flow rate sensor (hot film anemometry) and glucose biosensor (amperometric sensor) have been successfully fabricated and fully integrated outside the spirally rolled polymer tube (ID = 500 microm, OD = 650 microm) of this demonstration device. The fabricated sensors showed good performances not only in a planar configuration but also in a spirally rolled configuration. This flexible micro tube lab-chip system provides a generic platform for developing patient-specific "smart" microcatheters that incorporate microsensors, microactuators, microfluidic devices and wireless signal communication modules that are tailored for the patients' unique condition.
- Published
- 2008
- Full Text
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50. Superconductivity in the PbO-type structure alpha-FeSe.
- Author
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Hsu FC, Luo JY, Yeh KW, Chen TK, Huang TW, Wu PM, Lee YC, Huang YL, Chu YY, Yan DC, and Wu MK
- Abstract
The recent discovery of superconductivity with relatively high transition temperature (Tc) in the layered iron-based quaternary oxypnictides La[O(1-x)F(x)] FeAs by Kamihara et al. [Kamihara Y, Watanabe T, Hirano M, Hosono H (2008) Iron-based layered superconductor La[O1-xFx] FeAs (x = 0.05-0.12) with Tc = 26 K. J Am Chem Soc 130:3296-3297.] was a real surprise and has generated tremendous interest. Although superconductivity exists in alloy that contains the element Fe, LaOMPn (with M = Fe, Ni; and Pn = P and As) is the first system where Fe plays the key role to the occurrence of superconductivity. LaOMPn has a layered crystal structure with an Fe-based plane. It is quite natural to search whether there exists other Fe based planar compounds that exhibit superconductivity. Here, we report the observation of superconductivity with zero-resistance transition temperature at 8 K in the PbO-type alpha-FeSe compound. A key observation is that the clean superconducting phase exists only in those samples prepared with intentional Se deficiency. FeSe, compared with LaOFeAs, is less toxic and much easier to handle. What is truly striking is that this compound has the same, perhaps simpler, planar crystal sublattice as the layered oxypnictides. Therefore, this result provides an opportunity to better understand the underlying mechanism of superconductivity in this class of unconventional superconductors.
- Published
- 2008
- Full Text
- View/download PDF
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