Effects of nutrients on α-amyiase production and plasmid stability in fed-batch culture of recombinant bacteria

Escherichia coli harbouring a recombinant plasmid containing the α-amylase gene (HB101/pHI301) and its derivative which can stably maintain the plasmid (HB101/pHI301A) were cultivated in a mini-jar fermenter. By controlling dissolved oxygen (DO) at a concentration of 2–3 μg/l and supplementing with suitable amounts of nutrients, the organisms could grow to a concentration (up to 40 g dry cell l^?1) in a semi-synthetic casamino acid medium. During culture the plasmid was maintained stably in both strains. In a synthetic medium, both micro-organisms grew less well and plasmid-free segregants were observed with HB101/pHI301 during the fed-batch culture. On the other hand, plasmid pHI301A was stably maintained throughout the fed-batch culture of HB101/pHI301A. Growth inhibitors, which may be metabolic products, accumulated in the medium and reduced bacterial growth.     

R/G and Y/B opponent-color mechanisms revealed in temporal integration for bichromatically mixed lights

In the present study, the critical durations for temporal integration at theshold were obtained for bichromatically mixed (red/green and yellow/blue) test lights presented against darkness and achromatic backgrounds of different intensities. Critical durations crucially depended on the mixing ratio of the red and green components: it was shortest when red and green components were balanced in intensity canceling chromaticness of both components, and longer for red and green monochromatic lights. This trend was pronounced with backgrounds of higher intensities but was not obvious with dim backgrounds. The results of yellow/blue condition showed that critical durations were shorter when yellow component was dominant, as well as when yellow and blue components were balanced in intensity canceling chromaticness of both components, but when blue monochromatic light was dominant, it was longer than in other mixture conditions and changed less with the elevation of the background intensity. The results were interpreted as demonstraing the red/green and yellow/blue opponet-color mechanism's participation.     

Organic materials for nonlinear optics

This review discusses nonlinear optical (NLO) polymeric materials. As an example of a second-order NLO material, a novel copolymer with a diazo dye attached is investigated. The second-order NLO coefficient χ⁽²⁾ of the copolymer reaches 1.0 × 10^?6 esu, which is 7 times larger than that of LiNbO₃. A third-order NLO coefficient χ⁽³⁾ larger than 10^?10 esu is obtained for polymers where NLO dyes are introduced into the polymer backbone. The optical transmission loss of these polymers is revealed to be around 2 dB/cm. As these polymers can be formed into channel waveguides using the photo-bleaching technique, they show promise for use in NLO devices because of their processability, transparency and large optical nonlinearity.     

Managing transboundary rivers: The case of the Mekong river basin

Abstract

During the last decade, leaders of the Mekong Countries have found it mutually advantageous to open up the Mekong Sub‐Region (MR) for development and trade, which promises some degree of political stability and regional security. Within the present political, cultural, and economic dynamics, the Mekong River Basin (MRB) ‐ one of the major international river basins in MR ‐ is a powerful catalyst for regional cooperation that facilitates sustainable development and regional stability; if, that is, the effective management intervention is in place to make sure that the benefits and costs of river basin development are spread equitably and peacefully. Nonetheless, there are numerous stumbling blocks in achieving integrated and balanced MRB management, such as limited success in real basin wide planning, implementation and monitoring and a poor knowledge base for supporting informed decision making and, finally, political impediments.

A workable and truly regional cooperative mechanism for integrated management of the MRB is yet to be developed, regardless of the existence of numerous regional institutions and organizations. The present paper proposes new schemes with (re)designing principles and performance determinants for a regional cooperative mechanism.     

Thermoelectric properties of A-site doped perovskites (Sr0.6Ba0.4)1−xMxPbO3 (M = La, K)

La- and K-doped perovskite-type ceramics, (Sr_0.6Ba_0.4)_1−xLa_xPbO₃ with x = 0.0−0.1 and (Sr_0.6Ba_0.4)_1−xK_xPbO₃ with x = 0.00−0.15, were prepared to modify thermoelectric properties of semi-metallic Sr_0.6Ba_0.4PbO₃ via the doping of electrons and holes, respectively. The electrical conductivity σ and Seebeck coefficient S for the ceramics were measured at temperatures of 373–1073 K in air. With the La doping, electron carriers were successively doped and the material changed from a semi-metal for the undoped Sr_0.6Ba_0.4PbO₃ to a metal for the (Sr_0.6Ba_0.4)_0.9La_0.1PbO₃. With the K doping, the thermoelectric properties were essentially unchanged probably due to the carrier compensation effect by the generation of oxygen deficiencies. The thermoelectric power factor S²σ was maximized to a value of 3.1 × 10⁻⁴ Wm⁻¹ K⁻² at 773 K for the undoped Sr_0.6Ba_0.4PbO₃ ceramic.     

A Strain‐Mediated Magnetoelectric‐Spin‐Torque Hybrid Structure

Magnetization dynamics induced by spin–orbit torques in a heavy‐metal/ferromagnet can potentially be used to design low‐power spintronics and logic devices. Recent computations have suggested that a strain‐mediated spin–orbit torque (SOT) switching in magnetoelectric (ME) heterostructures is fast, energy‐efficient, and permits a deterministic 180° magnetization switching. However, its experimental realization has remained elusive. Here, the coexistence of the strain‐mediated ME coupling and the SOT in a CoFeB/Pt/ferroelectric hybrid structure is shown experimentally. The voltage‐induced strain only slightly modifies the efficiency of SOT generation, but it gives rise to an effective magnetic anisotropy and rotates the magnetic easy axis which eliminates the incubation delay in current‐induced magnetization switching. The phase field simulations show that the electric‐field‐induced effective magnetic anisotropy field can reduce the switching time approximately by a factor of three for SOT in‐plane magnetization switching. It is anticipated that such strain‐mediated ME‐SOT hybrid structures may enable field‐free, ultrafast magnetization switching.     

Effect of γ-ray Irradiation on the Wettability of TiO2 Single Crystals

The contact angles of the water droplets on TiO₂ single crystal surfaces decreased and became superhydrophilic state by γ-ray irradiation. It was found that these behaviors were dependent on γ-ray irradiation atmosphere, i.e., in air and in N₂ atmosphere (r. h.; 30%) as well as crystal faces of TiO₂ single crystals, i.e., TiO₂ (100) and (110) surfaces. It was also found from the results of UV–Vis and ESR measurements that γ-ray irradiation under N₂ atmosphere led to the oxygen vacancies and associated Ti³⁺, regardless of the presence of gaseous water. Moreover, it was suggested that the organic molecules adsorbed on TiO₂ single crystal surfaces decomposed by γ-ray irradiation.     

Synthesis and Properties of Glassy Microcavities for Morphology-Dependent Resonances through Liquid–Liquid Phase Separation

Glassy microspheres containing a rare earth are attractive for practical use as microcavities for morphology-dependent resonances (MDRs). However, no efficient and low-cost mass-production process has been established for such microcavities. In the present study, we have synthesized glassy microcavities through liquid–liquid phase separation of alkaline-earth borate glass. Glassy microspheres have been prepared by the liquid–liquid phase separation of BaO-B₂O₃ glasses, by controlling the particle size within the range 1–45 μm and the size distribution within 1%. The microspheres show periodic, sharp peaks, indicative of MDRs, in their Raman-scattering spectra and in the fluorescence spectra of the internal rare earth. These microspheres act as high-quality microcavities, with Q factors comparable to those calculated using the Lorenz–Mie theory.