Graphene‐based nanocomposites are characterized by high mechanical strength, excellent electrical conductivity, and outstanding thermal and chemical stability. Additionally, the combination of ...versatile functionalization chemistry and simplicity of large‐scale synthesis makes graphene ideal for electrode materials for energy storage devices. To improve the electrochemical performance even further, recent research has focused on the preparation of porous graphene structures, either by creating holes in the graphene sheets or by assembling them into a 3D porous framework. Porous graphene and reduced graphene oxide allow for rapid ion diffusion and display high real surface area. In this review paper, the conventional methods for the preparation of porous graphene are summarized and recent progress in porous graphene‐based nanomaterials for electrochemical energy storage devices is discussed.
The different ways porous graphene can be synthesized and its application in energy storage devices are summarized in this review. Porous graphene‐based electrodes display enhanced performance over normal graphene, since the pores allow for rapid ion diffusion. Particular focus is given to porous graphene‐based batteries and supercapacitors.
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•Defect-rich heterostructure of Zn-birnessite nanosheet@spinel ZnMn2O4 nanocrystal is obtained for flexible supercapacitor.•Mechanism of birnessite-to-spinel phase transition driven ...by oxygen vacancy (Vo) is elucidated.•The presence of Vo and hetero-interface within the birnessite@spinel heterostructure improves its capacitance utilization.
Defect engineering holds great promise to boost surface charge redox chemistry of pseudocapacitive materials. However, their innovative development on the heterogeneous structure is still lacking. Herein, defect-rich heterogeneous Zn-birnessite nanosheet@spinel ZnMn2O4 nanocrystal composites are designed via an in situ chemical reduction route at a low temperature. We explore the formation mechanism that the generated oxygen vacancy (Vo) in the Zn-birnessite triggers Mn cation migration, leading to birnessite-to-spinel phase transition. The defect-rich heterostructure supplies rich Mn2+/3+/4+ redox couples, multiple electrochemically active sites, and shortened ion-transport pathways. Moreover, the bandgap of the heterostructure is reduced from 1.54 eV to 1.06 eV after introducing Vo, which promotes electron transport and thus bolsters fast redox reaction kinetics. Accordingly, the heterostructure delivers a large areal capacitance of 1903 mF cm−2 at 3 mA cm−2 at a wide potential window of 1.2 V, high rate performance, and long cycle life (93.7% capacitance retention over 16,000 cycles). An asymmetric supercapacitor employing the heterostructure as a cathode and vanadium oxide as an anode exhibits a high voltage of 2.4 V, and possesses a maximum energy density of 6.24 mWh cm−3. This research offers a promising avenue to tailor the electrochemical reactivity of heterostructures through defect engineering.
Vascular vertigo: updates Choi, Kwang-Dong; Kim, Ji-Soo
Journal of neurology,
1/8, Volume:
266, Issue:
8
Journal Article
Peer reviewed
Discriminating strokes in patients with acute dizziness/vertigo is challenging especially when other symptoms and signs of central nervous involvements are not evident. Despite the developments in ...imaging technology over the decades, a significant proportion of acute strokes may escape detection on imaging especially during the acute phase or when the lesions are small. Thus, small strokes causing isolated dizziness/vertigo would have a higher chance of misdiagnosis in the emergency department. Even though several diagnostic algorithms have been advanced for acute vascular vertigo, we still await more comprehensive and sophisticated ones that can also be applied to transient vestibular symptoms due to vascular compromise. In this respect, vascular and perfusion imaging would be informative. Application of artificial intelligence and tele-consultation may be future perspectives for real-time decision in acute dizziness and vertigo. Several new constellations of ocular motor and vestibular findings have been added to the strokes involving the brainstem and cerebellum. Defining these characteristics would help understanding the function of central vestibular structures and allow more accurate localization of the strokes involving these structures.
Diagnosis of lymphoma involving the central nervous system (CNS) is challenging. This study aimed to explore the abnormal vestibular and ocular motor findings in CNS lymphoma.
A retrospective search ...of the medical records identified 30 patients with CNS lymphoma presenting ocular motor and vestibular abnormalities from four neurology clinics of university hospitals in South Korea (22 men, age range 14-81 years, mean 60.6 ± 15.2). The demographic and clinical features and the results of laboratory, radiological and pathological evaluation were analyzed.
Patients presented with diplopia (13/30, 43%), vestibular symptoms (15/30, 50%) or both (2/30, 7%). In 15 patients with diplopia, abnormal ocular motor findings included ocular motor nerve palsy (n = 10, 67%), internuclear ophthalmoplegia (n = 2, 13%), external ophthalmoplegia (n = 2, 13%) and exophoria (n = 1, 7%). The vestibular abnormalities were isolated in 14 (82%) of 17 patients with vestibular symptoms and included combined unilateral peripheral and central vestibulopathy in three from lesions involving the vestibular nuclei. CNS lymphoma involved the brainstem (53%), cerebellum (33%), leptomeninges (30%), deep gray nuclei (23%) or cranial nerves (17%). Two patients showed the "double-panda" sign by involving the midbrain.
This study expands the clinical and radiological spectra of CNS lymphoma. Neuro-ophthalmological and neuro-otological evaluation may guide the early diagnosis of CNS lymphoma.
Episodic ataxia (EA) is a rare neurological condition characterized by recurrent spells of truncal ataxia and incoordination. Five genes (KCNA1, CACNA1A, CACNB4, SLC1A3, and UBR4) have been linked to ...EA. Despite extensive efforts to genetically diagnose EA, many patients remain still undiagnosed. Whole-exome sequencing was carried out in 39 Korean patients with EA to identify pathogenic mutations of the five known EA genes. We also evaluated 40 candidate genes that cause EA as a secondary phenotype or cerebellar ataxia. Eighteen patients (46%) revealed genetic information useful for establishing a molecular diagnosis of EA. In 11 patients, 16 pathogenic mutations were detected in three EA genes. These included nine mutations in CACNA1A, three in SLC1A3, and four in UBR4. Three patients had mutations in two genes, either CACNA1A and SLC1A3 or CACNA1A and UBR4, suggesting that SLC1A3 and UBR4 may act as genetic modifiers with synergic effects on the abnormal presynaptic activity caused by CACNA1A mutations. In seven patients with negative results for screening of EA genes, potential pathogenic mutations were identified in the candidate genes ATP1A2, SCN1A, TTBK2, TGM6, FGF14, and KCND3. This study demonstrates the genetic heterogeneity of Korean EA, and indicates that whole-exome sequencing may be useful for molecular genetic diagnosis of EA.
N-myc downstream-regulated gene 2 (NDRG2) is a tumor-suppressor gene that suppresses tumorigenesis and metastasis of tumors and increases sensitivity to anti-cancer drugs. In this review, we ...summarize information on the clinicopathological characteristics of tumor patients according to NDRG2 expression in various tumor tissues and provide information on the metastasis inhibition-related cell signaling modulation by NDRG2. Loss of NDRG2 expression is a prognostic factor that correlates with TNM grade and tumor metastasis and has an inverse relationship with patient survival in various tumor patients. NDRG2 inhibits cell signaling, such as AKT-, NF-κB-, STAT3-, and TGF-β-mediated signaling, to induce tumor metastasis, and induces activation of GSK-3β which has anti-tumor effects. Although NDRG2 operates as an adaptor protein to mediate the interaction between kinases and phosphatases, which is essential in regulating cell signaling related to tumor metastasis, the molecular mechanism of NDRG2 as an adapter protein does not seem to be fully elucidated. This review aims to assist the research design regarding NDRG2 function as an adaptor protein and suggests NDRG2 as a molecular target to inhibit tumor metastasis and improve the prognosis in tumor patients.
Highlights
CNT/MnO
2
/graphene-grafted carbon cloth electrode is designed and achieves high MnO
2
mass loading (9.1 mg cm
−2
).
The electrode with favorable electronic/ionic conductivity delivers a ...large areal capacitance and rate capability.
The assembled asymmetric supercapacitor yields a large energy density of 10.18 mWh cm
−3
.
Flexible supercapacitor electrodes with high mass loading are crucial for obtaining favorable electrochemical performance but still challenging due to sluggish electron and ion transport. Herein, rationally designed CNT/MnO
2
/graphene-grafted carbon cloth electrodes are prepared by a “graft-deposit-coat” strategy. Due to the large surface area and good conductivity, graphene grafted on carbon cloth offers additional surface areas for the uniform deposition of MnO
2
(9.1 mg cm
−2
) and facilitates charge transfer. Meanwhile, the nanostructured MnO
2
provides abundant electroactive sites and short ion transport distance, and CNT coated on MnO
2
acts as interconnected conductive “highways” to accelerate the electron transport, significantly improving redox reaction kinetics. Benefiting from high mass loading of electroactive materials, favorable conductivity, and a porous structure, the electrode achieves large areal capacitances without compromising rate capability. The assembled asymmetric supercapacitor demonstrates a wide working voltage (2.2 V) and high energy density of 10.18 mWh cm
−3
.
Objectives
Persistent postural‐perceptual dizziness (PPPD) is a chronic functional vestibular disorder for which the Bárány Society has established diagnostic criteria. This nationwide multicenter ...study aims to investigate the clinical features of individuals with definite PPPD and clinical variant PPPD who do not fully meet the diagnostic criteria, with a particular focus on visual exaggeration.
Methods
Between September 2020 and September 2021, a total of 76 individuals with definite PPPD and 109 individuals with clinical variant PPPD who did not meet all three exacerbating factors outlined in Criterion B were recruited from 18 medical centers in South Korea. The study gathered information on demographic factors, clinical manifestations, balance scales, and personality assessments.
Results
Comparative analysis between groups with definite PPPD and clinical variant with visual exacerbation revealed no significant differences in sociodemographic characteristics, clinical course, dizziness impact, and specific precipitants. Only disease duration was significantly longer in definite PPPD compared with variant with visual exacerbation. However, the variant without visual exacerbation displayed significantly reduced rates of panic disorder, diminished space‐motion discomfort, lesser impact of dizziness, and decreased prevalence of depression when compared with the definitive PPPD.
Conclusion
This is the first comprehensive nationwide study examining clinical features of both definite PPPD patients and its clinical variants, considering visual exacerbating factors. Differences in dizziness and personality traits emerged between definite PPPD and its potential variant without visual issues. Our results highlight the possibility of a distinct clinical variant of PPPD influenced by visual dependency.
Recently, transition-metal phosphides and phosphates have been recognized as candidates for electrochemical energy storage and conversion application. However, the preparation of such materials ...usually requires high energy consumption and toxic precursors which are considered to be drawbacks for real applications. In this study, we report ambient temperature synthesis of transition-metal phosphates for oxygen evolution reaction (OER) and supercapacitors. The prepared iron-doped porous nickel pyrophosphate (NFPy) nanoparticle is synthesized via simple stirring in ambient temperature using only the precursor for Ni, Fe, and pyrophosphate without any heat treatment. The usage of pyrophosphate promotes facile Ni oxidation and high chemical stability, which overall is beneficial for electrochemical applications and the environment. The OER performance of NFPy shows promising results which required an overpotential of 0.210 V to reach 10 mA·cm–2. Also, with the help of carbon nanotubes, the supercapacitor using NFPy exhibits a good electrochemical performance with a capacity of 517 C·g–1 at 1 A·g–1. The prepared NFPy possesses excellent long-term chemical stability that maintained its chemical valence state and electrochemical performance for over 8 months despite the exposure of air.
The fabrication of activated hierarchical porous carbon materials normally requires multiple processing steps involving pyrolysis and activation with long reaction times under controlled gas ...conditions. This article presents an ultrafast and scalable synthesis of hierarchical porous activated carbon via one-step microwave heating, using a homogeneous mixture of potassium citrate and carbon black. For this work, the mixture was simply covered with a glass chamber to accompany spontaneous changes in environmental conditions from air to CO/CO2 gases. Under microwave irradiation, simultaneous carbonization and activation processes were completed within a very short period of time, resulting in the formation of hierarchical porous carbon with a high specific surface area of 1280.4 m2 g−1. When the prepared porous carbon was used as an electrode material for electric double-layer capacitors, it exhibited a remarkable specific capacitance of 318 F g−1 at a current density of 1 A g−1 in a three-electrode system. In addition, the electric double-layer capacitor using the optimized porous carbon showed a high energy density of 0.55 mWh cm−3 with a power density of 12.92 mW cm−3, as well as excellent long-term cycle stability in a symmetric two-electrode configuration.
•Hierarchical porous carbon materials are synthesized by ultrafast microwave heating.•Simultaneous carbonization and activation are rapidly completed in ambient air.•The products exhibit high specific surface area and excellent specific capacitance.•The products can be utilized as supercapacitor electrodes without post-treatment.•It shows great potential for high-performance supercapacitor applications.
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