Reduction of Graphene Oxide and its Effect on Square Resistance of Reduced Graphene Oxide Films

Zhaoxia Hou,Yin Zhou,Guangbin Li,Shaohong Wang,Meihan Wang,Xiaodan Hu,Siming Li 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.6

Graphite oxide was prepared via the modified Hummers’ method and graphene via chemical reduction. Deoxygenation efficiency of graphene oxide was compared among single reductants including sodium borohydride, hydrohalic acids, hydrazine hydrate, and vitamin C. Two-step reduction of graphene oxide was primarily studied. The reduced graphene oxide was characterized by XRD, TG, SEM, XPS, and Raman spectroscopy. Square resistance was measured as well. Results showed that films with single-step N2H4 reduction have the best transmittance and electrical conductivity with square resistance of ~5746 Ω/sq at 70% transmittance. This provided an experimental basis of using graphene for electronic device applications.

An exchange bias observed in Tb/Cr/FeCo trilayers with ultrathin Cr layer at low temperature

Sun Li,Li Xiaoyan,Zhang Yiwei,Song Hengbo,Zhang Wen,Kou Zhaoxia,Zhang Dong,Liu Xiaoying,Fei Hongyang,Pan Mengmei,Zhao Zhibin,Zhai Ya 한국물리학회 2022 Current Applied Physics Vol.44 No.-

Positive exchange bias field (He) is observed in Tb/Cr (tCr)/FeCo trilayers at 5 K without cooling field, and negative He for Tb/FeCo bilayer. The negative He of Tb/FeCo implies the FM coupling at the interface due to Co and Fe dominate in the magnetization of the ferrimagnetic interlayer alloy of FeCo and Tb. With the inserting of Cr layer, this situation is broken, and the positive He implies the antiferromagnetic interlayer coupling. A peak of He = 6.0 mT for trilayers with tCr = 1.5 nm is corresponding to the minimum value of coercivity as a function of tCr at 5 K, which is used to study the effect of the cooling field (Hfc) on He as a function of temperature. It is found that Hfc of 100 mT triggers He from positive to negative at T ≤ 15 K. The magnetoresistance results also confirm the coexistence of multiple MR mechanisms in these trilayers.

A Novel Filter for Harmonics and Inter-harmonics Analysis and Suppression in AC Electronic Load

Huang Zhaoxia,Zou Xudong,Li Fen,Zou Yunping,Tong Li 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

AC electronic load (ACEL) based on current-controlled AC/DC/AC PWM converters is a simple kind of application for ac power source burn-in test with energy recycling capability. According to instantaneous power theory, the harmonics relationship in steady state between the ac side and the dc side of AC/DC converter and DC/AC converter in ACEL is investigated. When the frequency of the tested source is different from that of the grid, the harmonics and inter-modulation production in the dc bus is analyzed in detail, The accuracy of the harmonics relationship and theoretical expectation in ACEL are demonstrated by Matlab/Simulink simulations under different operation conditions. In addition, to decrease intrinsic-harmonics voltage of dc bus, a novel algorithm for output current reference is put forward. The proposed method is validated to be effective for suppressing the output current harmonics and inter-harmonics inject to the grid by simulations and experiments.

Controlling Magnetic Dipole Resonance in Raspberry-like Metamolecules

Li, Chen,Lee, Sunghee,Qian, Zhaoxia,Woods, Connor,Park, So-Jung,Fakhraai, Zahra American Chemical Society 2018 The Journal of Physical Chemistry Part C Vol.122 No.12

<P>Raspberry-like metamolecules (RMMs), clusters of closely packed noble metal nanobeads self-assembled on a dielectric core, exhibit emergent optical properties not available in simple nanoparticles. Examples include broad band far-field extinction and artificial optical magnetism. An important feature of these clusters is that their magnetic plasmon resonance and the breadth of their extinction spectra can be tuned via simple synthetic routes, such as by changing the bead size, core size, or the average interbead distance. However, the effect of each of these variables on the final magnetic resonance frequency and strength has not been studied in depth. Understanding how to tune the electric and magnetic resonance modes in these clusters can help improve the design of novel metamaterials for various applications. In this article, we combine theoretical analyses using numerical finite-different time-domain modeling and analytical dipole-dipole coupling theory to study the role of these variables in the global electric and global magnetic dipole modes of RMMs. We also demonstrate that these variables can be readily controlled experimentally using surfactants with varying lengths or changing synthetic conditions and show that the experimental results are consistent with theoretical predictions. The results provide a guideline for synthesizing plasmonic nanoparticle assemblies when specific resonant frequencies and bandwidths are desired.</P> [FIG OMISSION]</BR>

The Video-Urodynamic and Electrophysiological Characteristics in Patients With Traumatic Spinal Cord Injury

Zhaoxia Wang,Han Deng,Xing Li,Limin Liao 대한배뇨장애요실금학회 2021 International Neurourology Journal Vol.25 No.4

Purpose: To investigate the video-urodynamic and pelvic floor electrophysiological characteristics in patients with traumatic spinal cord injury (SCI). Methods: This retrospective reviewed the clinical records, urodynamic and pelvic floor electrophysiological data of 647 patients with traumatic SCI and out of spinal shock. Patients were classified based on American Spinal Injury Association (ASIA) Impairment Scale and urodynamic findings. Results: Of the 647 patients, detrusor overactivity (DO) with or without detrusor sphincter dyssynergia (DSD) was found in 79.5%, 61%, 35.2%, 35%, and 19.2% of patients with cervical, thoracic (T1–9), thoracic (T10–12), lumbar, and conical cauda injury, respectively. Other patients manifested detrusor areflexia (DA). Patients with DO and/or DSD had a longer duration of SCI at each injury level than patients with DA. In suprasacral injury patients with DA, 63.0% (58 of 92) had a normal bulbocavernosus reflex (BCR) response. Compared with patients without bladder sensation (BS), bladder capacity during urine leakage was far higher in those with BS. The manifestation of BCR and somatosensory-evoked potential (SEP) was associated with the level of injury. Conclusions: This study showed a significant correlation between the level of SCI and video-urodynamic findings, but clinical examination cannot by predict bladder function; urodynamic testing is also necessary. In addition, the role of BCR and SEP for guiding bladder management is limited. Moreover, BS is important for urinary control in patients with traumatic SCI.

Raspberry-like Metamolecules Exhibiting Strong Magnetic Resonances

Qian, Zhaoxia,Hastings, Simon P.,Li, Chen,Edward, Brian,McGinn, Christine K,Engheta, Nader,Fakhraai, Zahra,Park, So-Jung American Chemical Society 2015 ACS NANO Vol.9 No.2

<P>We report a synthetic approach to produce raspberry-like plasmonic nanostructures with unusually strong magnetic resonances, termed raspberry-like metamolecules (raspberry-MMs). The synthesis based on the surfactant-assisted templated seed-growth method allows for the simultaneous one-step synthesis and assembly of well-insulated gold nanoparticles. The aromatic surfactant used for the syntheses forms a thin protective layer around the nanoparticles, preventing them from touching each other and making it possible to pack discrete nanoparticles at close distances in a single cluster. The resulting isotropic gold nanoparticle clusters (<I>i</I>.<I>e</I>., raspberry-MMs) exhibit unusually broad extinction spectra in the visible and near-IR region. Finite-difference time-domain (FDTD) modeling showed that the raspberry-MMs support strong magnetic resonances that contribute significantly to the broadband spectra. The strong magnetic scattering was also verified by far-field scattering measurements, which show that in the near-IR region the magnetic dipole resonance can be even stronger than the electric dipole resonance in these raspberry-MMs. Structural parameters such as the size and the number of gold nanoparticles composing raspberry-MMs can be readily tuned in our synthetic method. A series of syntheses with varying structure parameters, along with FDTD modeling and mode analyses of corresponding model structures, showed that the close packing of a large number of metal nanoparticles in raspberry-MMs is responsible for the unusually strong magnetic resonances observed here.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2015/ancac3.2015.9.issue-2/nn5050678/production/images/medium/nn-2014-050678_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn5050678'>ACS Electronic Supporting Info</A></P>

Frequency-Dependent Effects on Bladder Reflex by Saphenous Nerve Stimulation and a Possible Action Mechanism of Tibial Nerve Stimulation in Cats

Xing Li,Xiaoping Wan,Zhaoxia Wang,Yanan Liang,Zhuo Jia,Xu Zhang,Limin Liao 대한배뇨장애요실금학회 2021 International Neurourology Journal Vol.25 No.2

Purpose: The present study determined the effects of saphenous nerve stimulation (SNS) at different stimulation frequencies on bladder reflex and explored a possible action mechanism of tibial nerve stimulation (TNS) on bladder activity in cats. Methods: Two bipolar nerve cuff electrodes were implanted on the saphenous nerve and the contralateral tibial nerve in 13 cats, respectively. Multiple cystometrograms were obtained to determine the effects of single SNS at different frequencies and that of combined SNS and TNS on the micturition reflex by infusing normal saline. Results: SNS at 1 Hz significantly reduced the bladder capacity (BC) to 59.8%±7.7% and 59.3%±5.8% of the control level at the intensity threshold (T) and 2T, respectively (P<0.05), while that at 20 Hz significantly increased the BC to 130.6%±4.2% of the control level at 6T (P<0.05). The TNS and SNS at 20 Hz did not significantly change the BCs at 1T (P>0.05), while combined stimulation at 1T significantly increased the BC to 122.7%±1.9% of the control level and induced an inhibitory effect which was similar to that TNS at 2T. Conclusions: The current study revealed that SNS reduced and increased BC depending on different stimulation frequencies. The combined SNS and TNS maximized the clinical efficacy at a low intensity. Also, SNS may be a potential therapeutic mechanism of TNS.

Unusual Weak Interparticle Distance Dependence in Raman Enhancement from Nanoparticle Dimers

Qian, Zhaoxia,Li, Chen,Fakhraai, Zahra,Park, So-Jung American Chemical Society 2016 The Journal of Physical Chemistry Part C Vol.120 No.3

<P>Here, we report surprisingly weak distance dependence in Raman enhancement from a raspberry-like gold nanoparticle termed raspberry-MM. A raspberry-MM is composed of closely packed gold nanobeads assembled on a polymer core. Due to the abundant 'built-in' hot spots between adjacent gold nanobeads, bright and uniform Raman signals were observed from isolated single raspberry-MMs. Interestingly, dimers of raspberry-MMs also showed highly reproducible Raman signals, indicating that the dimer SERS signal is not strongly dependent on the nanoparticle separation. Finitedifference timedomain (FDTD) modeling shows that a strong hot spot is created at the dimer-gap, as expected. However, since there are many more built-in hot spots in each raspberry MM, the contribution of the dimer-gap hot spot to the total Raman enhancement remains low even for 2 nm separation, which explains the observed weak distance dependence. This result is in stark contrast with many previous SERS studies on nanoparticle dimers and clusters, and provides an important guideline on how to design bright and highly reproducible Raman substrates.</P>

Effects of Acute Sacral Neuromodulation at Different Frequencies on Bladder Overactivity in Pigs

Xing Li,Limin Liao,Guoqing Chen,Zhaoxia Wang,Han Deng 대한배뇨장애요실금학회 2017 International Neurourology Journal Vol.21 No.2

Purpose: We investigated the effects of different stimulation frequencies on the inhibition of bladder overactivity by sacral neuromodulation (SNM) in pigs. Methods: Implant-driven stimulators were used to stimulate the S3 spinal nerve in 13 pigs. Cystometry was performed by infusing normal saline (NS) or acetic acid (AA). SNM (pulse width, 210 μsec) at frequencies ranging from 5 to 50 Hz was conducted at the intensity threshold at which observable perianal and/or tail movement was induced. Multiple cystometrograms were performed to determine the effects of different frequencies on the micturition reflex. Results: AA-induced bladder overactivity significantly reduced the bladder capacity (BC) to 34.4%±4.7% of the NS control level (354.4±35.9 mL) (P<0.05). During AA infusion, SNM at 5 Hz did not significantly change the BC (48.1%±6.9% of the NS control level) (P>0.05), but SNM at 15, 30, and 50 Hz significantly increased the BC to 54.5%±7.1%, 55.2%±6.5%, and 57.2%±6.1% of the NS control level (P<0.05), respectively. No significant differences were found among the results obtained using frequencies of 15, 30, and 50 Hz (P>0.05). Conclusions: This study demonstrated that 15 Hz was an appropriate frequency for SNM and that frequencies higher than 15 Hz did not lead to better surgical outcomes.

以法律职业为目标的法学本科研究型教学实践与思考

张朝霞 ( Zhang Zhaoxia ),李孟超 ( Li Mengchao ),韦梦琦 ( Wei Mengqi ) 경상대학교 교육연구원(구 경상대학교 중등교육연구소) 2021 중등교육연구 Vol.33 No.1

전문성을 갖춘 법학교육에 있어서 지식교육과 기술교육을 포함하는데, 기술교육으로는 스마트기술과 실무기술 등이 있다. 법조인 양성을 위한 법학교육은 법학지식과 더불어 스마트기술의 습득을 필요로 한다. 법학교육과 스마트기술의 습득은 미래사회가 인재에 대한 수요일 뿐만 아니라 업무의 효률성과도 연관되어 있다. 이러한 법학교육은 훌륭한 인재 양성을 위해 직업교육을 강화하고 전문적인 지식과 기술을 갖춘 법조인을 양성하는 데에 그 의미가 있다. 이를 위하여 법학교육의 실천과정에 지식전달 위주의 수업방식에서 실무능력 양성을 주요 특징으로 하는 연구형 수업방식으로 전환하여야 한다. 즉 전문적인 지식과 기술을 갖춘 법조인 양성을 위한 법학교육의 연구형 수업은 교수자의 주도하에 학습자들이 적극적으로 참여하는 연구형 수업방식이다. 이 과정에서 교수자와 학습자 간 협력하여 법률 지식과 스마트기술을 습득하는 질 높은 수업방식을 공동구축하도록 요구된다. 교육실천과정에서 나타나는 여러 문제점에 대비해 연구형 법학교육이 이상적인 학습효과를 달성하고 법률지식과 스마트기술을 갖춘 법조인을 양성하기 위해 아래 몇 가지 대안을 제시한다. 첫째, 연구형 수업의 실천과정에서 스마트기술의 습득이 우선시 되어야 한다. 둘째, 법학지식에 관한 검색능력을 강화해야 한다. 셋째, 교수자는 교육과정에서 특정 역할에 충실해야 한다. 넷째, 교수자와 학습자 간의 좋은 수업분위기를 조성하기 위하여 공동으로 노력해야 한다. In order to do a good job in professional legal education, we must distinguish skill and knowledge. Intelligent skills and practical skills. The teaching task of undergraduate law education aiming at legal profession should be to impart knowledge and cultivate intelligent skills, so that students can have solid legal knowledge, skill foundation and lifelong learning ability. The legal professional skills of students to effectively match and the future social demand for talents, education must take vocational education as the basic orientation of law, cultivate good professional skill of legal person, must stress that inquiry learning teaching of undergraduate course of law practice, to impart knowledge as the main characteristics of the type of teaching teaching to cultivate ability as the main characteristics of research-based teaching. The research-oriented teaching of law undergraduate with the goal of legal profession requires teachers to take the initiative to guide, students to take an active part in the research-oriented learning, and teachers and students to work together to construct a good teaching mode of legal knowledge impartation and legal intelligence skill training. In view of the problems in teaching practice, in order to achieve the ideal teaching effect and lay a solid foundation of legal knowledge and skills for the students to become outstanding legal talents, the following work must be done in the teaching: to make clear that the research exercise is the best way to cultivate intelligent skills; Strengthen the cultivation of students' legal information retrieval ability; Teachers take their role in teaching seriously; Build a good teaching atmosphere.