Luminescence nanothermometry with alkyl-capped silicon nanoparticles dispersed in nonpolar liquids

Silicon nanoparticles (Si NPs) with a diameter size ranging from 4 to 8 nm were successfully fabricated. They exhibit a visible photoluminescence (PL) due to the quantum confinement effect. Chemical functionalization of these Si NPs with alkyl groups allowed to homogeneously disperse them in nonpolar liquids (NPLs). In comparison to most of literature results for Si NPs, an important PL peak position variation with temperature (almost 1 meV/K) was obtained from 303 to 390 K. The influence of the liquid viscosity on the peak positions is also presented. These variations are discussed considering energy transfer between nanoparticles. The high PL thermal sensitivity of the alkyl-capped Si NPs paves the way for their future application as nanothermometers.     

Life cycle assessment and cost analysis of very large‐scale PV systems and suitable locations in the world

Although the Sahara region has a high potential for solar power plants, the amount of installed photovoltaic (PV) system remains relatively low. This paper aims to evaluate these potentials of PV system installation in terms of environmental and economic viewpoints with indices of cost, energy, and greenhouse gas (GHG) emission. Two 1‐GW very large‐scale PV systems are simulated at Ouarzazate in Morocco and at Carpentras in France. The evaluation was performed using life cycle assessment. The lowest energy consumption and GHG emission are obtained while assuming cadmium telluride module. The result of our simulation shows that energy payback time is 0.9 years and CO₂ emission rate is 27.4 g‐CO_2‐eq/kWh in the Ouarzazate case. In cost estimation, generation costs are 0.06 USD/kWh in Ouarzazate and 0.09 USD/kWh in Carpentras in the case of 3% interest rate and 0.5 USD/W for multicrystalline silicon PV module price. In addition, by adapting 15% internal rate of return for 20% of budget, the generation costs become 0.09 USD/kWh in Ouarzazate and 0.13 USD/kWh in Carpentras under the same condition. Furthermore, the selection for suitable locations to install solar power plants in term of GHG emission is identified using geographical information system. Very high‐potential locations (lower than 38 g‐CO_2‐eq/kWh) could be obtained in North Chili, east and west Sahara, and Mexico. Copyright © 2015 John Wiley & Sons, Ltd.     

One-Pot Microwave-Assisted Synthesis of Graphene/Layered Double Hydroxide (LDH) Nanohybrids

Nano-Micro Letters - A facile and rapid method to synthesize graphene/layered double hydroxide (LDH) nanohybrids by a microwave technique is demonstrated. The synthesis procedure involves...     

Toughening of poly(lactide) using polyethylene glycol methyl ether acrylate: Reactive versus physical blending

To design high‐performance poly(lactide)‐based materials (PLA‐based) with improved toughness, two approaches based on the reactive extrusion (REx) process are investigated and compared in the present study. The first approach relies upon a two‐step procedure using a REx‐polymerized poly(ethylene glycol) methyl ether acrylate, i.e., poly(AcrylPEG), as a highly‐branched and compatible impact modifier for PLA. The free‐radical polymerization proves to be very efficient with a peroxide initiator concentration of 1 wt%. The as‐produced poly(AcrylPEG) is then melt‐blended with PLA by extrusion. The resulting materials exhibit largely increase impact resistance (ca. 35 kJ/m²) in presence of 20 wt% poly(AcrylPEG) in comparison with neat PLA (2.7 kJ/m²), while moderate ductility (tensile elongation at break <40%) and limited plasticization effect are observed. The second “one‐step” approach consists in in situ grafting of AcrylPEG onto PLA backbone via a one‐stage REx. The resulting materials exhibit substantially improved impact resistance (ca. 102 kJ/m²) for AcrylPEG loading of 20 wt%, high ductility (tensile elongation at break of ca. 150%) and efficient plasticization. A detailed characterization of the morphology of the materials has been performed using PF‐QNM‐AFM to better elucidate the structure‐property relationships. POLYM. ENG. SCI., 55:1408–1419, 2015. © 2015 Society of Plastics Engineers     

Past‐Free[ze] reachability analysis: reaching further with DAG‐directed exhaustive state‐space analysis

Model‐checking enables the automated formal verification of software systems through the explicit enumeration of all the reachable states. While this technique has been successfully applied to industrial systems, it suffers from the state‐space explosion problem because of the exponential growth in the number of states with respect to the number of interacting components. In this paper, we present a new reachability analysis algorithm, named Past‐Free[ze], that reduces the state‐space explosion problem by freeing parts of the state‐space from memory. This algorithm relies on the explicit isolation of the acyclic parts of the system before analysis. The parallel composition of these parts drives the reachability analysis, the core of all model‐checkers. During the execution, the past states of the system are freed from memory making room for more future states. To enable counter‐example construction, the past states can be stored on external storage. To show the effectiveness of the approach, the algorithm was implemented in the OBP Observation Engine and was evaluated both on a synthetic benchmark and on realistic case studies from automotive and aerospace domains. The benchmark, composed of 50 test cases, shows that in average, 75% of the state‐space can be dropped from memory thus enabling the exploration of up to 14 times more states than traditional approaches. Moreover, in some cases, the reachability analysis time can be reduced by up to 25%. In realistic settings, the use of Past‐Free[ze] enabled the exploration of a state‐space 4.5 times larger on the automotive case study, where almost 50% of the states are freed from memory. Moreover, this approach offers the possibility of analyzing an arbitrary number of interactions between the environment and the system‐under‐verification; for instance, in the case of the aerospace example, 1000 pilot/system interactions could be analyzed unraveling an 80 GB state‐space using only 10 GB of memory. Copyright © 2016 John Wiley & Sons, Ltd.     

Polymyrcene microstructure revisited from precise high-field nuclear magnetic resonance analysis

The microstructural analysis of 1,4-cis- and of 1,4-trans-polymyrcene was conducted by means of thorough investigations at a very high field NMR (21.1T, 900 MHz). A set of 1D and 2D experiments helped to entirely assign the resonances of the spectra for both stereoisomers. A simple method to distinguish between each stereoisomer by NMR spectroscopy is finally provided.     

Controlled synthesis of crosslinked polyamide 6 using a bis-monomer derived from cyclized lysine

The controlled synthesis of polyamide 6 chemical networks by anionic ring-opening copolymerization of ε-caprolactam (CL) with synthesized bis-ε-caprolactam derived from α-amino-ε-caprolactam, i.e. N-functionalized α-amino-ε-caprolactam bis-monomers, using sodium ε-caprolactamate as an initiator and hexamethylene-1,6-dicarbamoylcaprolactam as di-functional fast activator was examined in bulk at 140 °C. An urea-based bis-monomer and CL were first shown to copolymerize with a decreasing polymerization rate due to side reactions. On the contrary, quantitative copolymerization of CL with various amounts of bis-N(2-oxo-3-azepanyl)-1,6-tetramethylenediamide, an amide-based bis-monomer, leads to fast kinetics similar to the homopolymerization of CL. Crosslinked PA6 with network exhibiting elastic or viscoelastic behaviors, depending on the amount of crosslinker, were observed and characterized by swelling in hexafluoroisopropanol, dynamic mechanical analysis and rheology measurements. Crystallinity and swelling were shown to decrease with the increasing content of the crosslinking agent.     

Distribution of 7Be, 210Pb and 137Cs in watersheds of different scales in the Seine River basin: inventories and residence times

The activity of environmental radionuclides ((7)Be, (210)Pb and (137)Cs) was monitored in nested catchments, inside the Seine River basin. Suspended matter data was collected at 8 different watersheds, ranging from order 1 to order 7, and ranging in size over 4 orders of magnitude. Suspended matter was analyzed for (210)Pb, (137)Cs and (7)Be, and used to calculate the flux of sediments out of each watershed. Monthly atmospheric flux data of (210)Pb and (7)Be was analyzed to assess the input flux of each into the watersheds, taking into account the rainfall during sampling periods. Taking advantage of the different half-lives of (7)Be (53 days) and (210)Pb (22 years), a two-box model was built for each of the catchments following a methodology previously developed by Dominik et al. [Dominik J, Burrus D, Vernet JP. Transport of the environmental radionuclides in alpine watershed. Earth Planet Sci Letters 1987; 84: 165-180.]. The model divides the watershed into a soil box and a rapid reservoir and provides insight into the removal rate of suspended matter from the surrounding watershed. The model enables the assessment of the surface area and the residence time of slow and rapid reservoirs to describe the fate of contaminants of atmospheric origin inside the river basin. The model was improved by considering the dissolved fraction in the total flux and adding the (137)Cs inventory as an additional constraint. The effects of these changes are discussed. Residence times in the soil box, characterized by low transport velocity, range between 4800 years at Melarchez (order 1) to about 30000 years at Andresy and Poses (order 7). They remain constant in each watershed over a large range of variation of atmospheric fluxes of (7)Be and (210)Pb during the whole study, but are sensitive to SM variations. The residence time in the rapid box, which includes the surface of the river and immediate surroundings, is less than one year, while its surface area is in the range 0.6% to 2.2% of the total catchment area. They are sensitive to (7)Be atmospheric flux variations. The two-box model was used to estimate the amount of the radionuclides in each reservoir. Inventories appear to be constant from one watershed to the next. The (7)Be inventory ratio in the rapid and slow boxes expresses the rate of particle-reactive atmospheric pollutants that will be rapidly delivered to the river.     

Occurrence of the <Emphasis Type="Italic">cis</Emphasis>-4,7,10, <Emphasis Type="Italic">trans</Emphasis>-13-22:4 Fatty Acid in the Family Pectinidae (Mollusca: Bivalvia)

The present study aimed to elucidate the effective phylogenetic specificity of distribution of a cis-4,7,10, trans-13-22:4 (22:4(n-9)Δ13trans) among pectinids. For this purpose, we extended the analysis of membrane glycerophospholipids FA composition to 13 species of scallops, covering 11 genera and 7 tribes representatives of the three subfamilies Chlamydinae, Palliolinae and Pectininae and the subgroup Aequipecten. In species belonging to the subfamily Pectininae and the Aequipecten subgroup, 22:4(n-9)Δ13trans was found in substantial amounts, but it was absent in other species belonging to the subfamilies Chlamydinae and Palliolinae. Homologous non-methylene-interrupted (NMI) FA, also hypothesized to differ along phylogenetic lines in bivalves, were totally absent or present only in trace amounts in representatives of the Aequipecten subgroup but ranged from 0.3 to 4.5% of the total FA in Pectinidae, Chlamydinae, and Palliolinae subfamilies. The species-specific occurrence of NMI and 22:4(n-9)Δ13trans FA in membrane lipids of pectinids agrees with the most recent phylogenies based on shell morphology and molecular characteristics. We examined the potential timing of the appearance of 22:4(n-9)Δ13trans in pectinids on a geologic time scale.