Temperature dependence of Mott transition in VO_2 and programmable critical temperature sensor

The temperature dependence of the Mott metal-insulator transition (MIT) is studied with a VO_2-based two-terminal device. When a constant voltage is applied to the device, an abrupt current jump is observed with temperature. With increasing applied voltages, the transition temperature of the MIT current jump decreases. We find a monoclinic and electronically correlated metal (MCM) phase between the abrupt current jump and the structural phase transition (SPT). After the transition from insulator to metal, a linear increase in current (or conductivity) is shown with temperature until the current becomes a constant maximum value above T_{SPT}=68^oC. The SPT is confirmed by micro-Raman spectroscopy measurements. Optical microscopy analysis reveals the absence of the local current path in micro scale in the VO_2 device. The current uniformly flows throughout the surface of the VO_2 film when the MIT occurs. This device can be used as a programmable critical temperature sensor.Comment: 4 pages, 3 figure

The Practice of Korean Medicine: An Overview of Clinical Trials in Acupuncture

Acupuncture, one of the Oriental medical therapeutic techniques that can be traced back at least 2500 years, is growing in popularity all over the world. Korea has continued to develop its own unique tradition of medicine throughout its long history, and has formed different types of acupuncture methods. The purpose of this review is to summarize clinical case studies in acupuncture and related therapies, such as acupressure, electric acupuncture, auricular acupuncture and moxibustion in Korea. A survey of Korean journals revealed that a total of 124 studies were published from 1983 to 2001. Results obtained from the survey showed that most clinical studies using acupuncture, electric acupuncture, moxibustion and other traditional therapies could alleviate a relatively broad range of medical problems. However, it should be emphasized that almost all clinical case studies published in various local journals did not follow the ‘good clinical practice’ with respect to regulatory aspects. Since they were not conducted using the randomized double-blinded controls with a large sample size, all the results should be considered as therapeutic indications. This review is an attempt to show the scope of acupuncture in our country and the kind of diseases, after many years of clinical experience, that were deemed valid targets for clinical trials

Monoclinic and Correlated Metal Phase in VO_2 as Evidence of the Mott Transition: Coherent Phonon Analysis

In femtosecond pump-probe measurements, the appearance of coherent phonon oscillations at 4.5 THz and 6.0 THz indicating the rutile metal phase of VO_2 does not occur simultaneously with the first-order metal-insulator transition (MIT) near 68^oC. The monoclinic and correlated metal(MCM) phase between the MIT and the structural phase transition (SPT) is generated by a photo-assisted hole excitation which is evidence of the Mott transition. The SPT between the MCM phase and the rutile metal phase occurs due to subsequent Joule heating. The MCM phase can be regarded as an intermediate non-equilibrium state.Comment: 4 pages, 2 figure

Ionothermal Synthesis of a Novel 3D Cobalt Coordination Polymer with a Uniquely Reported Framework: [BMI] 2

The framework of [RMI]2[Co2(BTC)2(H2O)2] (RMI = 1-alkyl-3-methylimidazolium, alkyl; ethyl (EMI); propyl (PMI); butyl (BMI)), which has uniquely occurred in ionothermal reactions of metal salts and H3BTC (1,3,5-benzenetricarboxylic acid), an organic ligand, reappeared in this work. Ionothermal reaction of cobalt acetate and H3BTC with [BMI]Br ionic liquid as the reaction medium yielded the novel coordination polymer [BMI]2[Co2(BTC)2(H2O)2] (compound B2). Similar ionothermal reactions with different [EMI]Br and [PMI]Br as the reaction media have been previously reported to produce [EMI]2[Co3(BTC)2(OAc)2] (compound A1) and [PMI]2[Co2(BTC)2(H2O)2] (compound B1), respectively. In contrast with the trinuclear secondary building unit of A1, the framework structure of B1 and B2 consists of dinuclear secondary building units in common, but with subtle distinction posed by the different size of the incorporated cations. These structural differences amidst the frameworks showed interesting aspects, including guest and void volume, and were used to explain the chemical trend observed in the system. Moreover, the physicochemical properties of the newly synthesized compound have been briefly discussed

Postanesthetic torsade de pointes in a patient with unrecognized long QT syndrome -A case report-

Torsade de pointes (TdP) is a devastating form of polymorphic ventricular arrhythmia associated with corrected QT (QTc) interval prolongation. TdP usually terminates spontaneously but frequently recurs and may degenerate to ventricular fibrillation. The present report describes a case of TdP in a patient being transferred to the postanesthetic care unit following an emergency laparoscopic appendectomy. The patient had undergone open heart surgery 1 week before. Retrospective electrocardiogram analysis revealed the patient had QTc and Tpeak-Tend interval prolongation that had gone unrecognized. We believe TdP may have been induced by accentuation of sympathetic nervous system during emergence from general anesthesia