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111.
Lee S Pirogov A Kang M Jang KH Yonemura M Kamiyama T Cheong SW Gozzo F Shin N Kimura H Noda Y Park JG 《Nature》2008,451(7180):805-808
The motion of atoms in a solid always responds to cooling or heating in a way that is consistent with the symmetry of the given space group of the solid to which they belong. When the atoms move, the electronic structure of the solid changes, leading to different physical properties. Therefore, the determination of where atoms are and what atoms do is a cornerstone of modern solid-state physics. However, experimental observations of atomic displacements measured as a function of temperature are very rare, because those displacements are, in almost all cases, exceedingly small. Here we show, using a combination of diffraction techniques, that the hexagonal manganites RMnO3 (where R is a rare-earth element) undergo an isostructural transition with exceptionally large atomic displacements: two orders of magnitude larger than those seen in any other magnetic material, resulting in an unusually strong magneto-elastic coupling. We follow the exact atomic displacements of all the atoms in the unit cell as a function of temperature and find consistency with theoretical predictions based on group theories. We argue that this gigantic magneto-elastic coupling in RMnO3 holds the key to the recently observed magneto-electric phenomenon in this intriguing class of materials. 相似文献
112.
This study investigated the extraction of 5'-phosphodiesterase from malt root and the degradation of nucleic acids by this enzyme. The extraction used grade precipitation with ammonium sulfate and enzymatic hydrolysis. Samples were assayed using the modified Bradford method and high performance liquid chromatography. The results show that 5'-phosphodiesterase is isolated by grade precipitation with 30% and 80% saturation of ammonium sulfate and can be utilized to degrade deoxyribonucleic acid. The hydrolysate has four kinds of deoxynucleotides: 5'-dCMP, 5'-dTMP, 5'-dAMP, and 5'-dGMP. The optimum reaction temperature is 70℃, and the optimum pH is 5.5-6.0 for the reaction. The percentage of deoxynucleotides indicated by the China Pharmacopoeia (2000 edition) in the product is over 70%. The extraction of 5'-phosphodiesterase from malt root is shown to be possible and economical. Products from the enzYmatic hydrolysate of DNA meet the pharmacopoeia. 相似文献
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115.
Joongkyu Park Woo-Joo Song Kwang Chul Chung 《Cellular and molecular life sciences : CMLS》2009,66(20):3235-3240
Down syndrome (DS) is associated with a variety of symptoms, such as incapacitating mental retardation and neurodegeneration
(i.e., Alzheimer’s disease), that prevent patients from leading fully independent lives. These phenotypes are a direct consequence
of the overexpression of chromosome 21 genes, which are present in duplicate due to non-disjunction of chromosome 21. Accumulating
data suggest that the chromosome 21 gene product, dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1A (Dyrk1A),
participates in the pathogenic mechanisms underlying the mental and other physical symptoms of DS. In this review, we summarize
the evidence supporting a role for Dyrk1A in DS, especially DS pathogenesis. Recently, several natural and synthetic compounds
have been identified as Dyrk1A inhibitors. Understanding the function and regulation of Dyrk1A may lead to the development
of novel therapeutic agents aimed at treating DS. 相似文献
116.
The state space model is widely used to handle time series data driven by related latent processes in many fields. In this article, we suggest a framework to examine the relationship between state space models and autoregressive integrated moving average (ARIMA) models by examining the existence and positive‐definiteness conditions implied by auto‐covariance structures. This study covers broad types of state space models frequently used in previous studies. We also suggest a simple statistical test to check whether a certain state space model is appropriate for the specific data. For illustration, we apply the suggested procedure in the analysis of the United States real gross domestic product data. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
117.
In this paper,to study the power loss of converter for elevator,The analysis is to establish relationship between parameters(current,voltages and losses in the inverter and converter) relevant for sizing of major components of the drive was done.) For high PWM(pulse width modulation) frequency like in elevator applications of fpwm =10kHz,switching losses are dominant and are about 2/3 of the total losses on IGBT switch.Transition from continuous 3 phase to discontinuous 2 phase PWM results in 50% reduction of switching loses on IGBT devices providing that PWM is not done over 60deg angle in a particular phase when current has maximum value.Total losses on IGBT(conduction + switching) are reduced approximately by ~1/3 what is still a significant reduction.Two phase PWM with reduced losses can be used for applications when acoustic noise due to increased current ripple is not significant and fall back solution to regular 3 phase PWM when drive operates under rare extreme conditions resulting in increased heat sink temperature.The analysis will be examined by further laboratory testing simulating 60% duty cycle on a dynamometer. 相似文献
118.
This paper presents a system to alert of dangerous a child situation of a child by applying context information collected from a home network to ontology that is capable of inference. Radio frequency Identification (RFID) and sensors were used for the configuration of a home network, to obtain the raw data to convert into context information. To express the ontology, web ontology language (OWL) was used to provide the inference of context information. Then, simple object access protocol (SOAP) messages were used to notify of the dangerous situations that a child may be involved in via mobile devices. The proposed system consists of Context Manager, Service Manager, and Notification Manager. The child's safety management system can proactively detect the context data of a child on the basis of context awareness. In the experiment, the Jena 2.0 by ontology reasoner and the OSGi(Open Service Gateway initiative) Gateway developed using open source software Knopflerfish 1.3.3 were used to implement the service frame work. 相似文献
119.
1 Results Polymeric light-emitting diodes (PLEDs) have attracted much scientific and technological research interest due to a number of advantages over inorganic or organic small molecules for use in LEDs: better processability,lower operating voltages,faster response times,lower production costs,and high flexibility.Polyfluorene has been selected for the polymer backbone,because of its large band gap,facile substitution at the C9 position of fluorene,good chemical and thermal stability,and high photolu... 相似文献
120.
Gated Single Assignment (GSA) form is used to transform an imperative program into a form suitable for dataflow interpretation. We describe a GSA-formed Control Flow Graph (CFG) that contains gating functions and the information of switches. We also present an algorithm to transform an imperative program into a GSA-formed CFG. Transformation of an imperative program into a GSA-formed CFG provides the basis for generating dataflow graphs(DFG). By using GSA-formed CFG, we can transform an imperative program into a DFG more simply comparing with previous methods, and show an expectation of use with demand- and control-driven model. As we create an intermediate form which has essential information for translation, it will be used to do transformations for various kinds of dataflow models. 相似文献