Regulation of the Cyanobacterial Circadian Clock by Electrochemically Controlled Extracellular Electron Transfer

There is growing awareness that circadian clocks are closely related to the intracellular redox state across a range of species. As the redox state is determined by the exchange of the redox species, electrochemically controlled extracellular electron transfer (EC‐EET), a process in which intracellular electrons are exchanged with extracellular electrodes, is a promising approach for the external regulation of circadian clocks. Herein, we discuss whether the circadian clock can be regulated by EC‐EET using the cyanobacterium Synechococcus elongatus PCC7942 as a model system. In vivo monitoring of chlorophyll fluorescence revealed that the redox state of the plastoquionone pool could be controlled with EC‐EET by simply changing the electrode potential. As a result, the endogenous circadian clock of S. elongatus cells was successfully entrained through periodically modulated EC‐EET by emulating the natural light/dark cycle, even under constant illumination conditions. This is the first example of regulating the biological clock by electrochemistry.     

磷酸钾缓冲溶液与模型细胞膜相互作用的和频光谱

利用和频光谱技术详细研究了磷酸钾缓冲溶液与带负电荷的生物仿生膜(d₅₄-DMPG磷脂双层膜)相互作用的实时过程．通过监控CD₂、CD₃、磷脂分子头部的磷酸根以及羰基官能团的光谱信号随加入磷酸钾缓冲溶液的实时变化,获得了磷脂双层膜分子结构的动力学变化．结果表明K⁺能够结合到细胞膜上,并且很快地引起了CD₂、CD₃、磷脂头部磷酸根以及羰基官能团信号的变化．根据各官能团的和频信号响应,磷酸钾缓冲溶液很可能是通过在双层膜中形成环形气孔来与磷脂双层膜发生作用．该结果可以很好地解释磷酸钾缓冲溶液环境下的离子协助蛋白质的跨膜过程．     

Flow Rate Prediction for a Semi-permeable Membrane at Low Reynolds Number in a Circular Pipe

Transport in Porous Media - A concise and accurate prediction method is required for membrane permeability in chemical engineering and biological fields. As a preliminary study on this topic, we...     

Optical testing of star sensor (II): Alignment of star sensor from off-line pictures taken in orbital test

Alignment error of an image sensor relative to the optical axis of a star sensor head and alignment errors between four heads were calculated from pictures taken in an orbital experiment. When comparing the image sensor alignment parameters in the orbital test and a ground test, both values matched well. By determining the relative relationship of the four heads using four pictures taken at the same moment in orbit and uploading the parameters to the star sensor system in orbit, the estimated attitude error was improved from 0.29 to 0.17°, though the accuracy was limited by the ±0.2° determination accuracy of the satellite itself. We estimated the attitude determination accuracy from separation angles between boresights of the four heads, calculated from pattern matching between downloaded pictures and a star catalogue. The estimated accuracy, in terms of potential optical performance, was 0.60 arcmin at 3σ, which is sufficient to satisfy the specification of 1 arcmin.     

Doppler-limited dye laser excitation spectroscopy of HCCl

The cw dye laser excitation spectrum of the $\text{A}\text{?}{}^1\text{A″(050) ←}\text{X}\text{?}{}^1\text{A′(000)}$ vibronic band of HCCl was observed between 16 539 and 16 656 cm^?1 with the Doppler-limited resolution, 0.03 cm^?1. The HCCl molecule was generated by the reaction of discharged CF₄ with CH₃Cl. The observed spectra were assigned to c-type transitions with ΔK_a = ±1 and also to axis-switching transitions with ΔK_a = 0 or ?2, but all with K′_a = 0, both for HC³⁵Cl and HC³⁷Cl. A rotational analysis yielded the rotational constants and quartic centrifugal distortion constants for the ground vibronic state and the band origin. A weak vibronic band, about one-third as intense as the main band, was found at about 57 cm^?1 to the violet of the main band for both isotopic species, and was ascribed to a transition from the ground vibronic state to a vibrational level, possibly (041), of the à state. The rotational levels of HC³⁵Cl in the à state showed a large perturbation; the J′ = 8, 9, and 10 levels were found to be split into two components. A normal coordinate analysis was carried out to calculate the centrifugal distortion constants and the inertia defect, which were in fair agreement with the observed values. The molecular structure of HCCl in the ground vibronic state was recalculated from the rotational constants of the two isotopic species combined with the 0.75B₀ + 0.25C₀ value previously reported for DC³⁵Cl.     

Design,fabrication and characterization of the X-ray supermirrors

With the development of the multiplayer technology, the multilayer mirrors have been widely used in many fields, such as the soft X-ray astronomical telescope, soft X-ray microscopy, extreme ultraviolet lithography, applications of synchrotron radiation, plasma diagnosis, and so on. However, in the hard X-ray region, especially for the wavelength shorter than 0.1 nm, the optical elements based on the traditional multilayers or the single high-Z metal coatings cannot accommodate the advancemen…     

Layer-by-layer electrodeposition of copper in the presence of o-phenanthroline, caused by a new type of hidden NDR oscillation with the effective electrode surface area as the key variable

Electrochemical deposition of copper (Cu) from aqueous acidic Cu2+ solutions with o-phenanthroline (o-phen) shows both potential and current oscillations, together with a (partially hidden) N-shaped negative differential resistance (N-NDR), indicating that the oscillations are classified into hidden N-NDR (or HN-NDR) oscillations. The color and the surface morphology of Cu deposits oscillate in synchronization with the potential and current oscillations. Microscopic inspection has shown that dense round Cu leaflets, which look gray, grow in the positive side of the potential oscillation or in the high-current state of the current oscillation, whereas thin Cu leaflets, which look black, grow in the opposite-side stages of the potential and current oscillations, thus finally resulting in a layered Cu deposit with the layer thickness of about 5 microm. The appearance of the NDR is explained to be due to adsorption of the reduced form of a [Cu(II)(o-phen)2]2+ complex, which suppresses the Cu electrodeposition. The increase in the effective electrode surface area by growth of thin Cu leaflets, on the other hand, causes a current increase that can hide the NDR. This NDR-hiding mechanism is of a new type and the present oscillation is regarded as a new-type of HN-NDR oscillator.