Construction of coacervate-in-coacervate multi-compartment protocells for spatial organization of enzymatic reactions

Coacervate microdroplets, formed via liquid–liquid phase separation, have been extensively explored as a compartment model for the construction of artificial cells or organelles. In this study, coacervate-in-coacervate multi-compartment protocells were constructed using four polyelectrolytes, in which carboxymethyl-dextran and diethylaminoethyl-dextran were deposited on the surface of as-prepared polydiallyldimethyl ammonium/deoxyribonucleic acid coacervate microdroplets through layer-by-layer assembly. The resulting multi-compartment protocells were composed from two immiscible coacervate phases with distinct physical and chemical properties. Molecule transport experiments indicated that small molecules could diffuse between two coacervate phases and that macromolecular enzymes could be retained. Furthermore, a competitive cascade enzymatic reaction of glucose oxidase/horseradish peroxidase–catalase was performed in the multi-compartment protocells. The different enzyme organization and productions of H₂O₂ led to a distinct polymerization of dopamine. The spatial organization of different enzymes in immiscible coacervate phases, the distinct reaction fluxes between coacervate phases, and the enzymatic cascade network led to distinguishable signal generation and product outputs. The development of this multi-compartment structure could pave the way toward the spatial organization of multi-enzyme cascades and provide new ideas for the design of organelle-containing artificial cells.

A coacervate-in-coacervate micro-architecture is constructed as a multi-compartment protocell model, in which a multi-enzyme cascade is spatially organized for competitive enzymatic reactions.     

一种基于网络最大可控子图的导航搜索模型

基于网络可控性模型提出了最大可控子图的概念,在此基础上提出了一种基于最大可控子图的导航搜索模型. 模型中基于最大可控子图的加边策略用最小的代价解决了有向网络搜索中存在的粒子因“无路可走”而终止搜索的问题;基于最大可控子图部署导航节点,仅用节点总数2%左右的导航点,就使全网搜索时间接近导航网络的平均最短路径. 通过在ER和SF 网络上的实验表明,全网搜索时间与网络的可控性有关,可控性越好,添加的边数量越少,同时会使网络中导航节点分布越多,越能提高网络的搜索效率. 关键词： 导航搜索 有向网 网络可控性     

In-fiber Mach–Zehnder interferometer based on multi-mode fiber and up-taper for curvature sensing

A new type of curvature sensor comprises a stub of multi-mode fiber and an up-taper is proposed and demonstrated experimentally. The whole fabrication process is quite simple and the sensor head is cost effective. Measurement results show that it has a maximum curvature sensitivity of −61.877 nm/m⁻¹ at 1.1718 m⁻¹ (the highest value of reported papers among in-fiber Mach–Zehnder interferometers) and −9.2115 nm/m⁻¹ from 0.865 m⁻¹ to 1.1172 m⁻¹. Temperature sensitivity of 89.01 pm/°C within the range of 20–80 °C has also been achieved, which implies the possibility for measurement of temperature.     

Maximum entropy networks are more controllable than preferential attachment networks

A maximum entropy (ME) method to generate typical scale-free networks has been recently introduced. We investigate the controllability of ME networks and Barabási–Albert preferential attachment networks. Our experimental results show that ME networks are significantly more easily controlled than BA networks of the same size and the same degree distribution. Moreover, the control profiles are used to provide insight into control properties of both classes of network. We identify and classify the driver nodes and analyze the connectivity of their neighbors. We find that driver nodes in ME networks have fewer mutual neighbors and that their neighbors have lower average degree. We conclude that the properties of the neighbors of driver node sensitively affect the network controllability. Hence, subtle and important structural differences exist between BA networks and typical scale-free networks of the same degree distribution.     

指数跟踪问题的广义双线性规划模型

本文对指数跟踪问题建立了一种广义的双线性规划模型,其中考虑了交易费用、持仓限制与重平衡问题.根据该模型的特殊结构,本文给出了近似规划算法,通过逐次逼近的线性规划求解最优指数跟踪问题.     

Studies on two-phase co-current air/non-Newtonian shear-thinning fluid flows in inclined smooth pipes

In this work, co-current flow characteristics of air/non-Newtonian liquid systems in inclined smooth pipes are studied experimentally and theoretically using transparent tubes of 20, 40 and 60 mm in diameter. Each tube includes two 10 m long pipe branches connected by a U-bend that is capable of being inclined to any angle, from a completely horizontal to a fully vertical position. The flow rate of each phase is varied over a wide range. The studied flow phenomena are bubbly flow, stratified flow, plug flow, slug flow, churn flow and annular flow. These are observed and recorded by a high-speed camera over a wide range of operating conditions. The effects of the liquid phase properties, the inclination angle and the pipe diameter on two-phase flow characteristics are systematically studied. The Heywood–Charles model for horizontal flow was modified to accommodate stratified flow in inclined pipes, taking into account the average void fraction and pressure drop of the mixture flow of a gas/non-Newtonian liquid. The pressure drop gradient model of Taitel and Barnea for a gas/Newtonian liquid slug flow was extended to include liquids possessing shear-thinning flow behaviour in inclined pipes. The comparison of the predicted values with the experimental data shows that the models presented here provide a reasonable estimate of the average void fraction and the corresponding pressure drop for the mixture flow of a gas/non-Newtonian liquid.     

The Analysis of Environmental Samples by Mass Spectrometry

Mass spectral analysis was carried out on shellfish samples taken in the vicinity of the Arrow oil spill at Chedabucto Bay, Nova Scotia. Oil samples were also analyzed, samples being obtained from the tanker and also from the beach.

After extraction of the oil and shellfish samples, group separations were made into aliphatic, aromatic and oxygenated fractions, which were analyzed separately by mass spectrometry. The validity of the group separations was established, since, in the analysis of the so-called aliphatic fraction, no evidence of aromatics could be seen by mass spectrometry.

On the other hand, polycyclic hydrocarbons were found in some of the aromatic fractions. Identification was based upon standard mass spectrometric analysis already performed on known examples of the polycyclics.

It was concluded that the possibility of oil contamination can be confirmed by the mass spectrometric analysis of appropriate samples. It was also concluded that the so-called control samples should have been taken at a greater distance from the oil spill.     

Near-infrared photothermal release of hydrogen sulfide from nanocomposite hydrogels for anti-inflammation applications

A novel near-infrared light photothemal-activated H2S-donating nanocomposite hydrogel was developed,through combination of a thermo-labile H2S donor and photothermal nanoparticles in agarose hydrogel.The polyethylenimine dithiocarbamate polymer,a thermo-labile compound,was synthesized as a novel H2S donor.The combination of a thermo-labile hydrogen sulfide donor and photothermal nanoparticles enabled the generation of H2S in agarose hydrogel upon irradiation with near-infrared light.The ability to modulate the photoirradiation for controlled generation and spatiotemporally release of H2S are its specific advantages.This photothermal spatiotemporally controlled H2S-releasing strategy was successfully applied to anti-inflammation treatment in a rat model,demonstrating its utility as a novel H2S-based therapeutic approach.