A quadruple-scanning-probe force microscope for electrical property measurements of microscopic materials

Four-terminal electrical measurement is realized on a microscopic structure in air, without a lithographic process, using a home-built quadruple-scanning-probe force microscope (QSPFM). The QSPFM has four probes whose positions are individually controlled by obtaining images of a sample in the manner of atomic force microscopy (AFM), and uses the probes as contacting electrodes for electrical measurements. A specially arranged tuning fork probe (TFP) is used as a self-detection force sensor to operate each probe in a frequency modulation AFM mode, resulting in simultaneous imaging of the same microscopic feature on an insulator using the four TFPs. Four-terminal electrical measurement is then demonstrated in air by placing each probe electrode in contact with a graphene flake exfoliated on a silicon dioxide film, and the sheet resistance of the flake is measured by the van der Pauw method. The present work shows that the QSPFM has the potential to measure the intrinsic electrical properties of a wide range of microscopic materials in situ without electrode fabrication.     

生物转化乳糖酸的研究

乳糖酸(Lactobionicacid)是乳糖氧化的产物,具有多种生理功能。目前,欧美等发达国家乳糖酸的生产是通过化学合成法,生产成本高,且有大量副产物生成。研究采用具有葡萄糖氧化酶的菌株BurkholderiacepaciaNo.24细胞培养物进行生物转化生产乳糖酸,55g湿重/1000mL细胞可将浓度为193mmol/L的乳糖转化成188mmol/L的乳糖酸,转化率可达99.8%,且转化液经薄层色谱层析和高效液相色谱检测证明在转化过程中没有副产物生成;同时,该菌株还具有广泛的底物专一性,能将葡萄糖、麦芽糖等糖类转化成相应的糖酸。     

Temperature dependence of cyclic creep behavior of a Cu–SiO2 bicrystal with a [0 1 1] 20° twist boundary

Temperature dependence of cyclic creep behavior has been studied using a Cu bicrystal containing dispersed SiO₂ particles and a [0 1 1] 20° twist boundary. Failure occurred at shorter times with increasing temperature and stress amplitude. The fracture-mode of the bicrystals changed sharply from transgranular to intergranular at a certain critical stress amplitude. The brittle intergranular fracture that occurred below the critical stress amplitude caused discontinuous life shortening. The observed fracture-mode change at the critical stress amplitude is discussed in relation to grain-boundary sliding and grain-boundary cracking.     

Beneficial effect of long-term combined treatment with voglibose and pioglitazone on pancreatic islet function of genetically diabetic GK rats

Vitamin A or its synthetic analogues are potent in controlling cell differentiation and in preventing epithelial cancer in experimental animals. Although some community-based studies have found that high serum retinol levels in prediagnostic sera were associated with reduced risk for cancer, other reports in humans have not confirmed this finding. This study is to evaluate the preoperative serum vitamin A level in breast cancer patients in Taiwan. The serum specimens were collected from 106 female cases of breast cancer (aged 30 to 70 years), 32 female cases of benign breast disease (aged 29 to 57 years), and 40 healthy females (aged 22 to 52 years). The serum vitamin A levels were measured by colorimetic analysis. The results showed the mean value of the vitamin A level was 140.4 +/- 65.7 micrograms/dl in the breast cancer group comparing to 145.2 +/- 44.2 micrograms/dl in the benign breast disease group, 144.0 +/- 30.0 micrograms/dl in the control group (P > 0.05). The characteristics of the breast cancer group were analyzed and they revealed that serum vitamin A levels did not bear statistically significant differences in age, duration, steroid receptor, tumor size and menopausal state. (P > 0.05) In conclusion, the serum vitamin A levels were not decreased in early breast cancer patients. The serum vitamin A levels were significantly decreased in the metastatic breast cancer group, especially in liver metastatic women. (P < 0.05). Postoperative vitamin A supplement may have potential benefit to metastatic breast cancer patients.     

Narrative scenario development based on cross-impact analysis for the evaluation of global-warming mitigation options

Social, technological, economic and environmental issues should be considered comprehensively for the evaluation of global-warming mitigation options. Existing integrated assessment models include assessment of quantitative factors; however, these models do not explicitly consider interactions among qualitative factors in the background – for example, introductions of nuclear power stations interact with social acceptability. In this paper, we applied a technological forecasting method – the cross-impact method – which explicitly deals with the relationships among relevant factors, and we then developed narrative scenarios having consistency with qualitative social contexts. An example of developed scenarios in 2050, assuming the global population and the gross domestic product are the same as those of the A1 scenario of the IPCC Special Report on Emissions Scenarios, tells us that: (1) the Internet will be extensively used in all regions; (2) the global unified market will appear; (3) regional cultures will tend to converge; (4) long-term investments (of more than 30 years) will become difficult and therefore nuclear-power stations will not increase so remarkably; (5) the self-sufficient supply and diversification of primary energy sources will not progress so rapidly; and (6) due to the widespread use of the Internet, people will be more educated in global environmental issues and environmental costs will be more socially acceptable.     

A control method for the matrix converter based on virtual AC/DC/AC conversion using carrier comparison method

This paper proposes a novel control method based on the virtual AC/DC/AC conversion for the matrix converter. The virtual AC/DC/AC conversion method is a very simple strategy to control the input current and the output voltage for the matrix converter. There are two new topics proposed in this paper. First, this paper proposes the minimum switching loss modulation on the virtual rectifier. In our proposed modulation, only two arms switching in the virtual rectifier using DC link current control by the virtual inverter can obtain clean sinusoidal input current. Second, a novel lean controlled carrier modulation on the virtual inverter is proposed. The leans of the triangle carrier are controlled by the duty ratio of the rectifier side pulse. The lean controlled carrier reduces harmonic distortion of the input current by avoiding interference between the rectifier control and the inverter control. These new proposals are confirmed by simulation and experimental results. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(3): 65–73, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20144     

Development of automatic fault point locating and sectional isolating system for power distribution line

This paper describes the development of the Automatic Fault Point Locating and Sectional Isolating System. This system locates a single-line-to-ground fault point at each pole by using ground-current sensors, and isolates the faulted section by controlling pole switches with no outage of unfaulted sections. The ground-current sensor is connected to the line between allied ground terminals of pole devices and grounded conductor. It detects a ground fault current of more than 0.64 amperes that is determined so as to avoid an unexpected operation by stray current, but to detect the fault current accurately, and sends out an emergency signal with time delay of 0.1 s. Sectional isolation starts when both the emergency signal from the sensor and relay operation signals from a substation are received and ends within a feeder circuit-breaker tripping time of 1.5 s.     

Determination of the best-fit values of kinetic parameters of the Michaelis-Menten equation by the method of least squares with the Taylor expansion

The best-fit values of the Michaelis constant (Km) and the maximum velocity (V) in the Michaelis-Menten equation can be obtained by the method of least squares with the Taylor expansion for the sum of squares of the absolute residual, i.e., the difference between the observed velocity and the corresponding velocity by calculation. This method makes it possible to determine the values of Km and V not in a trial-and-error manner but in a deductive and unique manner after some iterative procedures starting from arbitrary approximate values of Km and V. These values can be said to be uniquely determined for a set of data as the finally converged values are no longer dependent upon the initial approximate values of Km and V. It is also very important to obtain initial approximate values of parameters for the application of the method described above. A simple method is proposed to estimate the approximate values of parameters involved in fractional functions. The method of rearrangement after canceling of denominator of a fractional function can be utilized to obtain approximate values, not only for cases of two unknown parameters such as the Michaelis-Menten equation, but also for cases with more than two unknowns.     

Development of competitive behavior as a function of culture, age, and social comparison.

Observed the choice behavior of 868 dyads of 2nd-, 4th-, and 6th-grade children from 5 different cultural backgrounds (Mexican-American, Anglo-American, Japanese, Greek, and Belgian) in the maximizing difference game, an outcome interdependence task where individualistic and cooperative motives were placed in opposition to competitive ones. In 4 cultures, boys received either social comparison feedback or only information concerning their own cumulative scores. As predicted, the level of competitive responding increased as a function of age, social comparison information, and number of trials. Further, there were systematic cultural differences. A newly developed covariation analysis revealed that individual dyad variation accounted for more covariation than the main effects noted above. Hence, several types of within-dyad analyses were performed. Finally, cultures were classified in terms of the characteristic play by dyad members and the results compared with a classification developed by M. Mead (1937), in which she ordered the cooperative, competitive, and individualistic orientations of members of 13 "primitive" societies. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preparation of mercaptoethylated graft fibers for adsorption of heavy metal ions

Various kinds of mercaptoethylated graft fibers were prepared and the abilities to adsorb the heavy metal ions were studied. 2-Hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and vinyl acetate were graft-copolymerized by irradiation onto five kinds of synthetic fibers and two kinds of foam polymers. Preirradiation at low temperature was far more effective for grafting than simultaneous irradiation. The mercaptoethylation was carried out in the solution or in the vapor of ethylene sulfide onto the graft fibers treated with alkali. The mercaptoethylated graft fibers showed particular affinity for Hg and Ag ions. A few of the adsorption phenomena were pursued by flow experiment of the ionic solution through a column. The preliminary reduction of the mercaptoethylated graft fibers enhanced the capacity of adsorbing to three times that of the unreduced fibers. Effects of flow rate, pH, temperature, and concentration of Hg ion on the integrated adsorbed amount were also investigated.