不同含量脱氢乙酸钠改性PVA薄膜 延长蛋糕保质期的研究

研究了不同脱氢乙酸钠含量的P V A薄膜对蛋糕保质期的影响,以得出最适于蛋糕保鲜用改性包装薄膜。首先,用流延法制备出以不同质量分数脱氢乙酸钠改性的P V A改性薄膜,然后将待测蛋糕切成一定规格并分别装入不同的PVA薄膜包装袋中进行贮藏试验。且每隔3 d,对样品蛋糕进行感官评价,并检测其失重率、菌落总数、酸价、过氧化值等,以评价改性包装的抑菌及抗油脂氧化效果。结果表明,添加脱氢乙酸钠改性后的PVA薄膜的保鲜效果均优于未改性PVA薄膜的;综合各因素的影响结果,确定添加质量分数为2%脱氢乙酸钠的改性PVA薄膜对蛋糕的保鲜效果较好,其不仅能有效阻止蛋糕中水分的流失,且蛋糕的抗氧化性能最强。     

Synthesis and characterization of core∕shell Fe(3)O(4)∕ZnSe fluorescent magnetic nanoparticles

We report on the successful preparation and characterization of fluorescent magnetic core∕shell Fe(3)O(4)∕ZnSe nanoparticles (NPs) with a spherical shape by organometallic synthesis. The 7 nm core∕3 nm shell NPs show good magnetic and photoluminescence (PL) responses. The observed PL emission∕excitation spectra are shifted to shorter wavelengths, compared to a reference ZnSe NP sample. A dramatic reduction of PL quantum yield is also observed. The temperature dependence of the magnetization for the core∕shell NPs shows the characteristic features of two coexisting and interacting magnetic (Fe(3)O(4)) and nonmagnetic (ZnSe) phases. Compared to a reference Fe(3)O(4) NP sample, the room-temperature Néel relaxation time in core∕shell NPs is three times longer.     

Sediment bed destabilization by an isolated vortex:an experimental approach

The destabilization of an erodible sediment bed by a reproducible impulsive phenomenon is studied experimentally.For this,a specific setup is designed to produc...     

Horizontal ramping rate framework to quantify hydropeaking stranding risk for fish

Hydropeaking due to hydropower production can have negative impacts on aquatic fauna. One of the mechanisms for causing impacts on fish and aquatic macroinvertebrates is linked to the rapid dewatering of habitats, which can result in stranding or trapping. The magnitude of these impacts depends both on the characteristics of the flow variations and of the river morphology, as well as biological parameters (species, behavior, etc). When discharge is rapidly reduced, the risk of impacts on fishes (and notably the risk of fish stranding in dewatered zones along the riverbank) is frequently assessed by calculations of vertical ramping velocity among other methods. However, to assess fish stranding risks, the lateral ramping velocity calculated as a horizontal ramping rate (HRR) appears to be a more relevant indicator as it directly measures shoreline drawdown rates. HRR has the advantage of integrating river morphology, but it remains challenging to calculate HRRs in complex situations such as braided rivers. Using hydraulic simulations of the Durance, a gravel bed braided river, we have developed an innovative approach for HRR calculation. Considering two simulated flows, the algorithms for the calculations require partitioning the finite elements into wet and drying meshes. To recommend rates of lowering discharges during hydropeaking events, further studies are required to evaluate more precisely HRR limits for fish stranding regarding biotic and abiotic parameters: species, sizes, nychthemeral cycles, temperature, substrate, and so forth.     

Access to High-Purity 7mG-cap RNA in Substantial Quantities by a Convenient All-Chemical Solid-Phase Method

Given the importance of mRNA with 5’-cap, easy access to RNA substrates with different ^7mG caps, of high quality and in large quantities is essential to elucidate the roles of RNA and the regulation of underlying processes. In addition to existing synthetic routes to 5’-cap RNA based on enzymatic, chemical or chemo-enzymatic methods, we present here an all-chemical method for synthetic RNA capping. The novelty of this study lies in the fact that the capping reaction is performed on solid-support after automated RNA assembly using commercial 2’-O-propionyloxymethyl ribonucleoside phosphoramidites, which enable final RNA deprotection under mild conditions while preserving both ^7mG-cap and RNA integrity. The capping reaction is efficiently carried out between a 5’-phosphoroimidazolide RNA anchored on the support and ^7mGDP in DMF in the presence of zinc chloride. Substantial amounts of ^7mG-cap RNA (from 1 to 28 nucleotides in length and of any sequence with or without internal methylations) containing various cap structures (^7mGpppA, ^7mGpppA_m, ^7mGppp^m6A, ^7mGppp^m6A_m, ^7mGpppG, ^7mGpppG_m) were obtained with high purity after IEX-HPLC purification. This capping method using solid-phase chemistry is convenient to perform and provides access to valuable RNA substrates as useful research tools to unravel specific issues regarding cap-related processes.     

Online handwriting trajectory reconstruction from kinematic sensors using temporal convolutional network

International Journal on Document Analysis and Recognition (IJDAR) - Handwriting with digital pens is a common way to facilitate human–computer interaction through the use of online...     

Minimal Architecture Lithium Batteries: Toward High Energy Density Storage Solutions

The coupling of thick and dense cathodes with anode-free lithium metal configuration is a promising path to enable the next generation of high energy density solid-state batteries. In this work, LiCoO₂ (30 µm)/LiPON/Ti is considered as a model system to study the correlation between fundamental electrode properties and cell electrochemical performance, and a physical model is proposed to understand the governing phenomena. The first cycle loss is demonstrated to be constant and independent of both cathode thickness and anode configuration, and only ascribed to the diffusion coefficient's abrupt fall at high lithium contents. Subsequent cycles achieve close to 100% coulombic efficiency. The examination of the effect of cathode thickness demonstrate a nearly linear correlation with areal specific capacity for sub-100 µm LiCoO₂ and 0.1 mA cm⁻² current density. These findings bring new insights to better understand the energy density limiting factors and to suggest potential optimization approaches.     

Analysis of dynamic flows through porous media. Part I: Comparison between saturated and unsaturated flows in fibrous reinforcements

This article presents a general approach to model flows through unsaturated porous media as they occur in Liquid Composite Molding (LCM). Saturated and unsaturated flows will be studied here both from the experimental and theoretical points of view. It is indeed important to distinguish between these two flow behaviors in order to understand the interactions between the three phases that coexist in a fibrous reinforcement: the solid and fluid phases on one hand, and the air content on the other. The experimental work presented here includes the study of permanent and transient flow regimes, both for saturated and unsaturated porous media. The dynamic effects that occur during fluid injection through fibrous reinforcements highlight the double scale, structure of their pore volume. The ratio between saturated and unsaturated permeabilities appears to be connected to the degree of saturation and to the porosity of the part. Given the importance of permeability as a key input parameter in process simulation, this article proposes to introduce the degree of saturation in the equations that govern the flow in order to increase the accuracy of numerical predictions. This will not only provide a better understanding of the underlying physical phenomena during the fluid impregnation of a fibrous preform, but will also ultimately allow the study of air entrapment mechanisms that govern the quality of composite parts.