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      • Zeolitic imidazolate frameworks derived novel polyhedral shaped hollow Co-B-O@Co<sub>3</sub>O<sub>4</sub> electrocatalyst for oxygen evolution reaction

        Kim, Dongwon,Kim, Daekyu,Jeon, Youngmoo,Li, Yong,Lee, Jeongyeon,Kang, Jeongmin,Lee, Lawrence Yoon Suk,Piao, Yuanzhe Elsevier 2019 ELECTROCHIMICA ACTA Vol.299 No.-

        <P><B>Abstract</B></P> <P>The development of highly effective and low-cost non-noble metal electrochemical catalysts for oxygen evolution reactions (OER) is a major challenge for overall water splitting and rechargeable metal-air batteries. In this study, we develop a novel hollow cobalt-borate modified cobalt oxide composite (denoted by Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB>) catalyst derived from zeolitic imidazolate framework-67 (ZIF-67) for electrochemical OER. The Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> was easily synthesized via pyrolysis of ZIF-67 in Ar and air to produce hollow Co<SUB>3</SUB>O<SUB>4</SUB> (denoted by h-Co<SUB>3</SUB>O<SUB>4</SUB>), followed by simple NaBH<SUB>4</SUB> treatment at ambient temperature for 4 h. The unique polyhedral morphology was well preserved during the NaBH<SUB>4</SUB> treatment. Benefiting from its structural and compositional merit, the as-synthesized Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> exhibit excellent electrocatalytic activity and long-term stability for OER. Also, we conducted the OER test using a Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> catalyst in a neutral pH environment for further investigation. Our study can provide an insight into catalyst modification step to enhance the overall performance while keeping its physical structure simultaneously. using metal-organic framework for the electrochemical catalyst thus can be recognized as a method for producing a highly active, long-term working and novel engineered electrocatalyst for OER applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> was prepared using calcination-NaBH<SUB>4</SUB> treatment strategy with a facile and energy efficient method. </LI> <LI> A distinctive polyhedral morphology of Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> was well preserved after the NaBH<SUB>4</SUB> treatment of its precursor material. </LI> <LI> Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> was employed for the electrochemical oxygen evolution reaction. </LI> <LI> Co-B-O@Co<SUB>3</SUB>O<SUB>4</SUB> showed excellent catalytic performance and long-term durability for oxygen evolution reaction in basic media. </LI> </UL> </P>

      • Community Discovering Algorithm based on Nodes with Maximum Degree and Label Propagation

        Li Shengli,Chen Deyun,Yao Yuanzhe 보안공학연구지원센터 2016 International Journal of Grid and Distributed Comp Vol.9 No.12

        Label propagation algorithm (LPA algorithm) is gotten widely attention by its simplicity, rapidity and greater effectiveness. Aimed at the problem of label updating process is sensitive to the order of nodes in LPA algorithm, an improved algorithm is proposed in this paper. The algorithm starts from the nodes with maximum degree in the network, according to its neighbor nodes’ community similarity index to decide whether its label setting, and then completes label setting in the first round; On this basis, it continues to carry out the iteration in label propagation algorithm, completes the entire network of community structure detection. The experimental results show that the improved algorithm is slightly better than the original algorithm at running time and number of iterations, has higher robustness, prevents the occurrence of the trivial solution.

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        Clinical Characteristics of Patients with Persistent Apogeotropic and Persistent Geotropic Direction-Changing Positional Nystagmus

        Si Lihong,Shen Bo,Li Yuanzhe,Ling Xia,Li Kangzhi,Yang Xu 대한신경과학회 2021 Journal of Clinical Neurology Vol.17 No.3

        Background and Purpose This study aimed to determine the clinical features, diagnosis, and treatment of patients with persistent geotropic (pG) and persistent apogeotropic (pAG) direction-changing positional nystagmus (DCPN). Methods This retrospective study included 30 patients with pG-DCPN and 44 patients with pAG-DCPN. All patients underwent neurological and neurotological examinations, including an evaluation of gaze-evoked nystagmus, eye-movement tests, and assessments of limb ataxia and balance, as well as magnetic resonance imaging to exclude central causes. The characteristics of positional nystagmus were detected using the supine roll test (SRT) and bow-andlean test (BLT). The null point (NP) at which the nystagmus disappeared was determined. All patients were treated with the barbecue maneuver, and treatment efficacy was evaluated immediately, 1 week, and 1 month after treatment. Results The history of diseases associated with atherosclerosis, peripheral vestibular disorders, otological disease, and migraine differed significantly between patients with pG-DCPN and pAG-DCPN. The affected sides of persistent horizontal DCPN can be determined using the SRT and the BLT, while determining the second NP and vestibular function as well as performing an audiological evaluation can be used to assist in identifying the affected side. The efficacy rates immediately and 1 week after treatment with the barbecue maneuver were higher in patients with pAG-DCPN than in patients with pG-DCPN. Conclusions pAG-DCPN was more compatible with the characteristics of cupulolithiasis, and pG-DCPN was more likely to be associated with a light cupula rather than canalolithiasis. pAG-DCPN was more likely to be accompanied by a disease associated with atherosclerosis, while pG-DCPN was often accompanied by autoimmune-related diseases and a history of migraine. The associations between pAG-DCPN, pG-DCPN, and the above-mentioned diseases need to be clarified further. The canalith-repositioning maneuver was effective in patients with pAG-DCPN and ineffective in patients with pG-DCPN, but most cases of pGDCPN are self-limiting.

      • One-Step Facile Solvothermal Synthesis of Copper Ferrite–Graphene Composite as a High-Performance Supercapacitor Material

        Zhang, Wang,Quan, Bo,Lee, Chaedong,Park, Seung-Keun,Li, Xinghe,Choi, Eunjin,Diao, Guowang,Piao, Yuanzhe American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.4

        <P>In this work, we reported a facile approach to prepare a uniform copper ferrite nanoparticle-attached graphene nanosheet (CuFe2O4-GN). A one-step solvothermal method featuring the reduction of graphene oxide and formation of CuFe2O4 nanoparticles was efficient, scalable, green, and controllable. The composite nanosheet was fully characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), which demonstrated that CuFe2O4 nanoparticles with a diameter of approximately 100 nm were densely and compactly deposited on GN. To investigate the formation mechanism of CuFe2O4-GN, we discussed in detail the effects of a series of experimental parameters, including the concentrations of the precursor, precipitation agent, stabilizer agent, and graphene oxide on the size and morphology of the resulting products. Furthermore, the electrochemical properties of the CuFe2O4-GN composite were studied by cyclic voltammetry and galvanostatic chargedischarge measurements. The composite showed high electrochemical capacitance (576.6 F.g(1) at 1 A.g(1)), good rate performance, and cycling stability. These results demonstrated that the composite, as a kind of electrode materials, had a high specific capacitance and good retention. The versatile CuFe2O4-GN holds great promise for application in a wide range of electrochemical fields because of the remarkable synergistic effects between CuFe2O4 nanoparticles and graphene.</P>

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