Moisture balance assessment at room scale for four cases based on numerical simulations of heat–air–moisture transfers for a realistic occupancy scenario

The moisture balance at room scale is influenced by the air change rate, moisture production and vapour transfer with the envelope. However, results may differ strongly from one study to another depending on the sizing of the ventilation system, the boundary conditions and the modelling of vapour transfer in the walls. This paper aims to provide a realistic comparison of usual construction techniques based on energy consumption, indoor comfort and durability. To achieve this objective, an existing whole-building heat–air–moisture simulation tool was selected to compute coupled transfer at room scale over an entire year. Moisture production due to occupancy was modelled using a stochastic approach. Four cases were selected to emphasize the differences of both a vapour-permeable wall assembly and a relative humidity sensitive ventilation system compared to common practices.     

3D electron microscopy study of metal particles inside multiwalled carbon nanotubes

The location of palladium nanoparticles on and inside the multiwalled carbon nanotubes channel is presented for the first time using electron tomography (3D TEM). The palladium salt precursor was rapidly sucked inside the nanotube channel by means of capillarity that is favored by the hydrophilic character of the tube wall after acidic treatment at low temperature. Statistical analysis indicates that the palladium particles were well dispersed and the palladium particle size was relatively homogeneous, ranging from 3 to 4 nm regardless of their location within the nanotube, within the resolution limit of the technique for our experimental conditions, i.e., about 2 nm. Three-dimensional TEM analysis also revealed that introduction of foreign elements inside the tube channel is strongly influenced by the diameter of the tube inner channel, i.e., easy filling seems to occur with a tube channel >or=30 nm , whereas with tubes having a smaller channel (<15 nm), almost no filling by capillarity occurred leading to the deposition of the metal particles only on the outer wall of the tube.     

Inhibition of Very Long Chain Fatty Acids Synthesis Mediates PI3P Homeostasis at Endosomal Compartments

A main characteristic of sphingolipids is the presence of a very long chain fatty acid (VLCFA) whose function in cellular processes is not yet fully understood. VLCFAs of sphingolipids are involved in the intracellular traffic to the vacuole and the maturation of early endosomes into late endosomes is one of the major pathways for vacuolar traffic. Additionally, the anionic phospholipid phosphatidylinositol-3-phosphate (PtdIns (3)P or PI3P) is involved in protein sorting and recruitment of small GTPase effectors at late endosomes/multivesicular bodies (MVBs) during vacuolar trafficking. In contrast to animal cells, PI3P mainly localizes to late endosomes in plant cells and to a minor extent to a discrete sub-domain of the plant’s early endosome (EE)/trans-Golgi network (TGN) where the endosomal maturation occurs. However, the mechanisms that control the relative levels of PI3P between TGN and MVBs are unknown. Using metazachlor, an inhibitor of VLCFA synthesis, we found that VLCFAs are involved in the TGN/MVB distribution of PI3P. This effect is independent from either synthesis of PI3P by PI3-kinase or degradation of PI(3,5)P₂ into PI3P by the SUPPRESSOR OF ACTIN1 (SAC1) phosphatase. Using high-resolution live cell imaging microscopy, we detected transient associations between TGNs and MVBs but VLCFAs are not involved in those interactions. Nonetheless, our results suggest that PI3P might be transferable from TGN to MVBs and that VLCFAs act in this process.     

SOCRATE: an optical bench dedicated to the understanding and improvement of a laser conditioning process

We present an automatic excimer laser bench (SOCRATE) allowing for the treatment of optical components by laser conditioning. This apparatus, developed at the Commissariat a l'Energie Atomique-Le Ripault, has been designed to add to this conditioning process an in situ, accurate laser-induced damage threshold (LIDT) measurement and different nondestructive optical techniques for the characterization of the component during treatment. Through different examples, we demonstrate the importance of these characterizations to improve the understanding of the laser conditioning. The role of an in situ adapted metrology associated in real time with a laser conditioning bench offers new opportunities to analyze laser-induced damage mechanisms and subsequently to increase the LIDT of optical components.     

Predictive modeling of piezoelectric wafer active sensors interaction with high-frequency structural waves and vibration

The modeling of the interaction between piezoelectric wafer active sensors (PWAS) and structural waves and vibration is addressed. Three main issues are discussed: (a) modeling of pitch-catch ultrasonic waves between a PWAS transmitter and a PWAS receiver by comparison between exact Lamb wave solutions and various finite element method (FEM) results; (b) analytical modeling of the power and energy transduction between PWAS and ultrasonic guided waves highlighting the tuning opportunities between PWAS and the waves; (c) the use of the transfer matrix method to model the electromechanical (E/M) impedance method for direct reading of high-frequency local structural vibration and comparison with FEM results. The paper ends with a summary and conclusions followed by recommendations for further work.     

Pattern-integrated interference lithography: single-exposure fabrication of photonic-crystal structures

Multibeam interference represents an approach for producing one-, two-, and three-dimensional periodic optical-intensity distributions with submicrometer features and periodicities. Accordingly, interference lithography (IL) has been used in a wide variety of applications, typically requiring additional lithographic steps to modify the periodic interference pattern and create integrated functional elements. In the present work, pattern-integrated interference lithography (PIIL) is introduced. PIIL is the integration of superposed pattern imaging with IL. Then a pattern-integrated interference exposure system (PIIES) is presented that implements PIIL by incorporating a projection imaging capability in a novel three-beam interference configuration. The purpose of this system is to fabricate, in a single-exposure step, a two-dimensional periodic photonic-crystal lattice with nonperiodic functional elements integrated into the periodic pattern. The design of the basic system is presented along with a model that simulates the resulting optical-intensity distribution at the system sample plane where the three beams simultaneously interfere and integrate a superposed image of the projected mask pattern. Appropriate performance metrics are defined in order to quantify the characteristics of the resulting photonic-crystal structure. These intensity and lattice-vector metrics differ markedly from the metrics used to evaluate traditional photolithographic imaging systems. Simulation and experimental results are presented that demonstrate the fabrication of example photonic-crystal structures in a single-exposure step. Example well-defined photonic-crystal structures exhibiting favorable intensity and lattice-vector metrics demonstrate the potential of PIIL for fabricating dense integrated optical circuits.     

Multiscale transparent electrode architecture for efficient light management and carrier collection in solar cells

The challenge for all photovoltaic technologies is to maximize light absorption, to convert photons with minimal losses into electric charges, and to efficiently extract them to the electrical circuit. For thin-film solar cells, all these tasks rely heavily on the transparent front electrode. Here we present a multiscale electrode architecture that allows us to achieve efficiencies as high as 14.1% with a thin-film silicon tandem solar cell employing only 3 μm of silicon. Our approach combines the versatility of nanoimprint lithography, the unusually high carrier mobility of hydrogenated indium oxide (over 100 cm(2)/V/s), and the unequaled light-scattering properties of self-textured zinc oxide. A multiscale texture provides light trapping over a broad wavelength range while ensuring an optimum morphology for the growth of high-quality silicon layers. A conductive bilayer stack guarantees carrier extraction while minimizing parasitic absorption losses. The tunability accessible through such multiscale electrode architecture offers unprecedented possibilities to address the trade-off between cell optical and electrical performance.     

Electrical and thermal conduction in atomic layer deposition nanobridges down to 7 nm thickness

While the literature is rich with data for the electrical behavior of nanotransistors based on semiconductor nanowires and carbon nanotubes, few data are available for ultrascaled metal interconnects that will be demanded by these devices. Atomic layer deposition (ALD), which uses a sequence of self-limiting surface reactions to achieve high-quality nanolayers, provides an unique opportunity to study the limits of electrical and thermal conduction in metal interconnects. This work measures and interprets the electrical and thermal conductivities of free-standing platinum films of thickness 7.3, 9.8, and 12.1 nm in the temperature range from 50 to 320 K. Conductivity data for the 7.3 nm bridge are reduced by 77.8% (electrical) and 66.3% (thermal) compared to bulk values due to electron scattering at material and grain boundaries. The measurement results indicate that the contribution of phonon conduction is significant in the total thermal conductivity of the ALD films.     

Evaluation of commercial lithium-ion cells based on composite positive electrode for plug-in hybrid electric vehicle applications. Part I: Initial characterizations

Evaluating commercial Li-ion batteries presents some unique benefits. One of them is to use cells made from established fabrication process and form factor, such as those offered by the 18650 cylindrical configuration, to provide a common platform to investigate and understand performance deficiency and aging mechanism of target chemistry. Such an approach shall afford us to derive relevant information without influence from processing or form factor variability that may skew our understanding on cell-level issues. A series of 1.9 Ah 18650 lithium ion cells developed by a commercial source using a composite positive electrode comprising {LiMn_1/3Ni_1/3Co_1/3O₂ + LiMn₂O₄} is being used as a platform for the investigation of certain key issues, particularly path-dependent aging and degradation in future plug-in hybrid electric vehicle (PHEV) applications, under the US Department of Energy's Applied Battery Research (ABR) program. Here we report in Part I the initial characterizations of the cell performance and Part II some aspects of cell degradation in 2C cycle aging. The initial characterizations, including cell-to-cell variability, are essential for life cycle performance characterization in the second part of the report when cell-aging phenomena are discussed. Due to the composite nature of the positive electrode, the features (or signature) derived from the incremental capacity (IC) of the cell appear rather complex. In this work, the method to index the observed IC peaks is discussed. Being able to index the IC signature in details is critical for analyzing and identifying degradation mechanism later in the cycle aging study.     

Superplastic Response of Continuously Cast AZ31B Magnesium Sheet Alloys

Magnesium sheet is typically produced for commercial applications with the traditional DC-ingot casting method. As a result of the hexagonal close-packed crystallographic structure in magnesium, multiple rolling passes and annealing steps are required to reduce the thickness of the ingots. Thus, high fabrication costs characterize the creation of magnesium sheet suitable for common forming operations. Recently, continuous casting (CC) technology, where molten metal is solidified directly into sheet form, has been applied to magnesium alloys; this method has shown the potential to significantly reduce the cost of fabricating magnesium sheet alloys. In order to understand the viability of the CC process, a study was conducted to investigate the superplastic potential of alloys produced by this method. This study focused on AZ31B Mg that was continuously-cast on twin-roll casters from three different suppliers. These three materials were compared with a production DC-cast AZ31B alloy in terms of microstructure, elevated-temperature tensile properties, and superplastic forming response. The data from this study found that microstructural features such as grain size and segregation can significantly affect the forming response. Additionally, the CC alloys can have equivalent or superior SPF response compared to DC-cast alloys, as demonstrated in both elevated temperature tensile tests and superplastic forming trials using a rectangular pan die.