In Vivo Simultaneous Analysis of Gene Expression by Dual-Color Luciferases in Caenorhabditis elegans

Both fluorescent and luminescent observation are widely used to examine real-time gene expression patterns in living organisms. Several fluuorescent and luminescent proteins with specific optical properties have been developed and applied for simultaneous, multi-color observation of more than two gene expression profiles. Compared to fluorescent proteins, however, the application of multi-color luminescent imaging in living organisms is still limited. In this study, we introduced two-color luciferases into the soil nematode C. elegans and performed simultaneous analysis of two gene expression profiles. Using a green-emitting luciferase Eluc (emerald luciferase) and red-emitting luciferase SLR (stable luciferase red), the expression patterns of two genes were simultaneously observed in single animals from embryonic to adult stages over its whole life span. In addition, dual gene activities were observed at the single embryo level, with the simultaneous observation of morphological changes. These are the first application of a two-color luciferase system into a whole animal and suggest that precise relationship of expression patterns of multiple genes of interest can be analyzed over the whole life of the animal, dependent on the changes in genetic and/or environmental conditions.     

Formation of bromo-substituted triclosan during chlorination by chlorine in the presence of trace levels of bromide

The side reactions of triclosan (2,4,4'-trichloro-2'-hydroxydiphenyl ether, TC) and chlorine in the presence of sodium chloride were investigated. In the absence of sodium chloride, three chloro-derivatives of TC, 2',3,4,4'-tetrachloro-2-hydroxydiphenyl ether (3-Cl-TC), 2',4,4',5-tetrachloro-2-hydroxydiphenyl ether (5-Cl-TC), and 2',3,4,4',5-pentachloro-2-hydroxydiphenyl ether (3,5-Cl(2)-TC) were formed, whereas in the presence of sodium chloride, 3-bromo-2',4,4'-trichloro-2-hydroxydiphenyl ether (3-Br-TC), 5-bromo-2',4,4'-trichloro-2-hydroxydiphenyl ether (5-Br-TC), (3 or 5)-bromo-2',4,4',(5 or 3)-chloro-2-hydroxydiphenyl ether ((3,5)-(BrCl)-TC), and 3,5-dibromo-2',4,4'-trichloro-2-hydroxydiphenyl ether (3,5-Br(2)-TC) were additionally formed. Radiochemical neutron activation analysis indicated that 1g of commercially available sodium chloride contained 73 microg of bromide and the bromide ion was determined to be the source of the side reactions. The rate of decrease of TC due to reaction with chlorine was greatly accelerated by the presence of bromide ion in the system: the rate with only 1 x 10(-5) M bromide ion was three times the rate in the absence of bromide.     

Characteristics of hydrogen-assisted intergranular fatigue crack growth in interstitial-free steel: role of plastic strain localization

The behavior of intergranular fatigue crack growth in an interstitial-free (IF) steel in a hydrogen environment was investigated at different frequencies. Focusing on the plastic strain localization, we observed details of the striation-like feature on the intergranular fracture surface, slip behavior around microvoids, and crystallographic orientation gradient underneath the fracture surface. It was determined that the intergranular fatigue crack growth mechanism in the IF steel is microvoid formation at the crack tip and subsequent coalescence with the crack. Moreover, it was found that the grain boundaries, acting as propagation paths, suffer from pre-damage arising from plastic strain localization near the grain boundaries even before the main crack propagates to a certain location. Therefore, fatigue cracks in a hydrogen environment easily propagate to the grain boundaries. The frequency dependence of fatigue crack growth in the hydrogen environment is significantly smaller than that in a low carbon steel, probably because of the frequency dependence of the pre-damage evolution behavior.     

填充热丝激光窄间隙焊接的实验研究

将填充热丝应用到高光束质量、长焦距的光纤激光窄间隙焊接中,不锈钢母材通过激光加热,镍基焊丝通过电流加热,有效利用复合热源的优势,提高了焊丝过渡稳定性和熔覆效率。通过高速摄像机对送丝过程进行在线观察,分析工艺参数对焊丝过渡的影响。研究不锈钢和镍基合金异种金属窄间隙焊接接头的凝固组织,并对焊缝金属进行元素分布扫描。研究发现,由焊丝电流和送丝速度等工艺参数决定的送丝稳定性是影响填充热丝激光焊接质量的最主要因素。对于窄间隙焊接,采用与间隙宽度相当的离焦光斑激光热导焊,可形成较好的侧壁熔合,由熔融金属曲面和侧壁构成的激光反射是侧壁熔合的主要原因。焊缝冷却速度较快,焊缝金属的凝固组织呈明显的对生生长,在坡口侧壁附近其生长方向与侧壁近似垂直,焊缝不存在宏观偏析。在间隙底部直角处容易出现未熔合现象,采用底部圆弧过渡的U型坡口后,可较好地解决底部未熔合问题,获得了无宏观缺陷的焊接接头。     

Electro-mechanical coupling in ionic gels

An ionic-polymer–metal-composite film shows electro-mechanical coupling. When the film is bent, electric current is induced. Measurement of the induced current indicates that the current depends on the speed of bending, but the total amount of the charge transferred across the film is independent of the speed, and depends only on the magnitude of the bending. The result indicates that in addition to previously proposed dynamical coupling effect, there is a static electro-mechanical coupling effect. Mathematical model is proposed to describe this phenomena.     

Incentive‐rewarding mechanism to stimulate activities in social networking services

We have developed an incentive‐rewarding mechanism that stimulates activities in social networking services (SNSs), including content uploading and link establishment. We particularly focus on changing the reward assignment ratio based on the different risks users perceive when uploading content with different privacy settings: public‐open and friend‐limited. Learning‐based simulation allowed us to observe that SNS activity, which we measured as the amount of browsed content within a certain period, can be controlled by a rewarding assignment ratio. We then analyzed how the amount of uploaded content and the increase of established links affect SNS activity. Results suggested that the optimal reward assignment ratio to maximize SNS activity changes depending on the total amount of available reward resources. Copyright © 2011 John Wiley & Sons, Ltd.     

Cathode properties of metal trifluorides in Li and Na secondary batteries

Fluorine compounds have high discharge voltage due to its highly ionic metal-ligand bonds. In them, perovskite-type metal trifluorides with corner sharing matrix have large bottlenecks of diffusion pathways for intercalants. Iron trifluoride composites (FeF₃-C) prepared by planetary ball milling with carbon showed reversible charge/discharge behavior not only for Li, but also for Na anodes. X-ray diffraction and ⁵⁷Fe Mössbauer spectroscopy were applied to characterize the electrochemical properties of FeF₃ vs. Li and Na anodes. The cathode performances of the other commercially available transition metal trifluorides such as MF₃ (M = Ti, V, Mn, Co) have been also investigated.     

Microstructure and mechanical properties of Pt-added and Pd-added Zr-20Nb alloys and their metal release in 1 mass% lactic acid solution

The effects of Pt and Pd addition to a Zr-20Nb alloy on its microstructure and mechanical property, as well as the elution of metals from the alloys in lactic acid solution, were investigated. The microstructure was characterized with an X-ray diffractometer (XRD), an optical microscope (OM), and a transmission electron microscope (TEM). The mechanical properties were evaluated by a tensile test. The β phase is dominantly observed in the Zr-20Nb as well as in the Pt-added and Pd-added Zr-20Nb alloys. Needle-like microstructures are observed in equiaxed grains in all alloys. Pd addition to the Zr-20Nb alloy suppresses ω phase formation more than Pt addition does. The 0.2% offset yield strength and the ultimate tensile strength of the Pt-added and Pd-added Zr-20Nb alloys increase with the Pt and Pd concentrations. XRD analysis revealed that the lattice parameter of β-Zr in the Pt-added and Pd-added Zr-20Nb alloys decreases with the Pt and Pd concentrations. Pt and Pd solute in β-Zr as a substitutional element and contribute to the increase in the strength by solid solution hardening. The addition of 2Pt and 2Pd to the Zr-20Nb alloy also improves metal elution from the alloys in lactic acid solution.