Packaging technology for improving shelf‐life of fruits based on a nanoporous–crystalline polymer

The ability of films with an active layer of nanoporous–crystalline syndiotactic polystyrene (s‐PS) to prolong shelf‐life, not only of climacteric but also of non‐climacteric fruits, is discussed. Studies on oxygen and carbon dioxide concentrations in the environment of packaged fruits as well as in s‐PS active layers have been combined. Reported results indicate that prolonged shelf‐life can be associated with large increases and decreases of carbon dioxide and oxygen concentrations inside the package, respectively. These data are consistent with a higher barrier offered to both gases by nanoporous–crystalline s‐PS layers. This barrier phenomenon is due to reduction of gas diffusivity typical of nanoporous–crystalline polymer films, which is further enhanced by orientation, parallel to the film plane, of crystalline planes of closely packed s‐PS helices. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46256.     

Solution structure of human corticotropin releasing factor by 1H NMR and distance geometry with restrained molecular dynamics

The structure of human corticotropin releasing factor (hCRF)has been determined by proton nuclear magnetic resonance (¹HNMR) in a mixed-solvent system of 66% trifluoroethanol/34% H₂Oat pH 3.8 and 37°C. Nearly complete resonance assignmentwas achieved by using standard two-dimensional methods. Distancerestraints for structure calculations were obtained by qualitativeanalysis of intra- and interresidue nuclear Overhauser effects.Structures were obtained from the distance restraints by distancegeometry, followed by refinement using molecular dynamics andwere completed with amide hydrogen exchange data. The structureof hCRF in this solvent comprises an extended N-terminal tetrapeptideconnected to a well-defined -helix between residues 6 and 36.The first half of the -helix (residues 6–20) is clearlyamphipathic. The five carboxy-terminal residues are predominantlydisordered.     

The Effects of Electronic Impurities and Electron–Hole Recombination Dynamics on Large‐Grain Organic–Inorganic Perovskite Photovoltaic Efficiencies

Hybrid organic‐inorganic perovskites have attracted considerable attention after promising developments in energy harvesting and other optoelectronic applications. However, further optimization will require a deeper understanding of the intrinsic photophysics of materials with relevant structural characteristics. Here, the dynamics of photoexcited charge carriers in large‐area grain organic‐inorganic perovskite thin films is investigated via confocal time‐resolved photoluminescence spectroscopy. It is found that the bimolecular recombination of free charges is the dominant decay mechanism at excitation densities relevant for photovoltaic applications. Bimolecular coefficients are found to be on the order of 10^?9 cm³ s^?1, comparable to typical direct‐gap semiconductors, yet significantly smaller than theoretically expected. It is also demonstrated that there is no degradation in carrier transport in these thin films due to electronic impurities. Suppressed electron–hole recombination and transport that is not limited by deep level defects provide a microscopic model for the superior performance of large‐area grain hybrid perovskites for photovoltaic applications.     

Stability Study of a Mixed Islanded Power Network

This paper presents the modelling, simulation and analysis of the dynamic behaviour of a mixed power network of 2.78 GW including hydro, thermal and wind power plants. The modelling of each power plant is described. The set of parameters of the turbine speed governor of the hydroelectric power plant is determined with a specific identification procedure to achieve stable operation for different cases such as interconnected, isolated or islanded operation. The analysis of the stability of the entire mixed islanded power plant is investigated through time domain simulations for different sets of controllers parameters and for different disturbances （load rejection and turbulent wind speed profile）.     

The Stroop and Reverse Stroop Effects as Measured by an Interactive Tabletop

An interactive tabletop equipped with RFID technology implemented the Stroop and reverse-Stroop tasks. Participants moved a tangible object into one of four displayed virtual zones, which were identified either by a color border or the name of a color written in black. The correct target zone corresponded either to the color (Stroop) or meaning (reverse Stroop) of a word displayed in congruent or incongruent colored LED lights (e.g., “YELLOW” displayed in yellow or red, respectively). Participants took more time to place the object in a zone, made more errors, and found the task more difficult when the word was lit with an incongruent than congruent color. This interference was influenced by both the types of task and response zone in a way that fits with a dual step processing account. Results also showed that the outcomes of the conflicting information streams might be judged as fun.     

Energy harvest with mangrove benthic microbial fuel cells

Benthic microbial fuel cells (BMFCs) are continuous electricity generators using electroactive microorganisms and organic matter from aquatic environment, respectively, as catalysts and substrate. In this paper, first a low‐cost PVC‐made structure is constructed to harvest electricity from mangrove environment located in French Guiana. An in situ BMFC has given power density of 30 mW/m² of the anodic surface area. This performance has been confirmed by experience in laboratory where inter‐electrode distance and electrode surface area appeared to be power increasing factors. However, the output power of one BMFC is not used to supply real devices such as autonomous sensors. Second, to meet this expectation, in parallel and in series associations were considered. These associations were made in order to increase the output voltage and consequently the power, to reach levels that can supply small sensors (about 3 V). Finally, to improve the performance of the series association and to avoid the voltage reversal phenomenon, a voltage balancing circuit was simulated and added to the series connections. With balancing method, the cell voltage of BMFCs can be equalized, and the performances can be improved. This allows an optimal energy harvesting and a better global efficiency of the set. Copyright © 2014 John Wiley & Sons, Ltd.     

驱动LED串的DCM升压转换器简化分析(1)——理论分析

固定频率升压转换器采用不连续导电模式(DCM)工作,能够有效地用于快速调光操作,提供比采用连续导电模式(CCM工作的竞争器件更优异的瞬态响应,这种转换器非常适合于以恒流模式驱动LED串。但驱动LED的升压转换器的交流分析,与使用标准电阻型负载的升压转换器的交流分析不同,在推导最终的传递函数时必须非常审慎。本文分为两个单元:⑴理论分析,介绍如何推导驱动LED串的升压转换器的小信号响应;⑵实际考虑,深入研究实施方案,并验证经验结果及与理论推导比较。