Outgoing longwave flux estimation: improvement of angular modelling using spectral information

A radiance-to-flux conversion is needed to estimate radiative fluxes at the top of the atmosphere from directional measurements made by broadband (BB) radiometers on satellites. Such a conversion is known to be one of the major sources of error in the resulting instantaneous shortwave and longwave fluxes. This paper analyzes the possibility to improve the radiance-to-flux conversion for the longwave radiation when spectral information about the radiation is available through a set of narrow-band (NB) measurements. The study is based on a database of spectral radiance fields at the top of the atmosphere built using radiative transfer computation. The analysis of this database shows that there exists a certain degree of correlation between the angular and the spectral behaviors of the radiation field. According to the type and the accuracy of the spectral information, this correlation allows a 25-55% reduction of the error introduced by the radiance-to-flux conversion with respect to a simple model that uses only broadband information. The method discussed in this paper might be used when broadband radiometer and spectral imager data are available together like the combination of Geostationary Earth Radiation Budget (GERB) and Spinning Enhanced Visible and Infrared Radiometer Imager (SEVIRI) or the combination of CERES and MODIS.     

Complications specific to posterior chamber lens implantation

The purpose of the study is to evaluate posterior chamber intraocular lenses complication, causes and their prevention.     

Computationally Efficient Formulation of Sparse Color Image Recovery in the JPEG Compressed Domain

Sparse representations provide a powerful framework for various image processing tasks, among which image recovery seems to be an already classical application. While most developments of image recovery applications are focused on finding the best dictionary, the possibility of using already existing sparse image representations tends to be ignored. This is the case of the JPEG compressed image representation, which is a sparse image representation in terms of the discrete cosine transform (DCT) dictionary. The development of sparse frameworks directly on the JPEG encoded image representation can lead to computationally efficient approaches. Here we introduce a DCT-based JPEG compressed domain formulation of the color image recovery process within a sparse representation framework and we prove mathematically and experimentally not only its numerical efficiency as compared to the pixel level formulation (the processing time is reduced up to 40 %), but also the good quality of the restoration results.     

Thermodynamic and kinetic study on ammonium removal from a synthetic water solution using ion exchange resin

Ammonium removal from the wastewater treatment effluents is mandatory considering the imposed discharge limits and the recycling/reuse requirements. Ion exchange represents a viable alternative for the biological processes of ammonium removal, although concurrent processes make modeling complex. This study reports on the performance of a commercial cation exchange resin, PUROLITE C150H, for ammonium removal from synthetic aqueous solutions. Thermodynamic and kinetic process parameters are calculated using the Langmuir model (thermodynamic study) and the shrinking core model (kinetic study); the data are correlated with the surface properties of the substrate, outlining the adsorption mechanism. For initial ammonium concentrations of 25–150 mg NH₄ ⁺/L, removal efficiencies of 80–90 % were obtained.     

Revealing the Dynamics of Hybrid Metal Halide Perovskite Formation via Multimodal In Situ Probes

The exploration of the synthetic space of halide perovskites hinges on an enormous number of parameters requiring time‐consuming experimentation to decouple and optimize. Here, the formation of the prototype material CH₃NH₃PbI₃ (MAPbI₃) is investigated at different time and length scales using multimodal in situ measurements to monitor the evolution of crystalline phases, morphology, and photoluminescence as a function of the lead precursors. Kinetically fast formation of crystalline precursor phases already during the spin‐coat deposition is observed using lead iodide (PbI₂) or lead chloride (PbCl₂) routes. These precursor phases most likely template final MAPbI₃ film morphology. In particular, the emergence of the “needle‐like” structure is shown to appear before film annealing. In situ photoluminescence measurements suggest nanoscale nucleation followed by rapid nuclei densification and growth. Using this multimodal in situ approach, different formation pathways can be identified either via precursor phases in the PbI₂ and PbCl₂ routes or direct perovskite formation from molecular building blocks as observed in the lead acetate (PbAc₂) route. Correlation of in situ results with photovoltaic device performance demonstrates the power of in situ multimodal techniques, paves the way to a fast screening of synthetic parameters, and ultimately leads to controlled synthetic procedures that yield high‐efficiency devices.     

Origin of rheological behavior and surface/interfacial properties of some semi-alicyclic polyimides for biomedical applications

High-performance alicyclic-containing polyimides for advanced applications, derived from 5-(2,5-dioxotetrahydrofurfuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride or bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and two flexible aromatic diamines, were synthesized by a classical two-step polycondensation reaction and analyzed by rheological method. The results were discussed according to the chemical structure of polyimides and their different properties, such as flexibility, hydrophobicity and surface morphology. It has been showed that the obtained parameters, controlled by the interactions occurring in the polyimide systems, can be correlated with the adhesion/cohesion of blood components and plasma proteins. Thus, the results of the work of spreading proteins on the hydrophobic polyimide surfaces indicated that albumin is not absorbed preferentially, while fibrinogen is characterized by a higher degree of adhesion on the surfaces, and also that selective adsorption of plasma proteins modifies blood compatibility. In addition, these results and the ascertained antimicrobial activity of the studied polyimides contribute to the development of new applications in the bio-technical field.     

Effect of magnetically simulated zero-gravity and enhanced gravity on the walk of the common fruitfly

Understanding the effects of gravity on biological organisms is vital to the success of future space missions. Previous studies in Earth orbit have shown that the common fruitfly (Drosophila melanogaster) walks more quickly and more frequently in microgravity, compared with its motion on Earth. However, flight preparation procedures and forces endured on launch made it difficult to implement on the Earth''s surface a control that exposed flies to the same sequence of major physical and environmental changes. To address the uncertainties concerning these behavioural anomalies, we have studied the walking paths of D. melanogaster in a pseudo-weightless environment (0g*) in our Earth-based laboratory. We used a strong magnetic field, produced by a superconducting solenoid, to induce a diamagnetic force on the flies that balanced the force of gravity. Simultaneously, two other groups of flies were exposed to a pseudo-hypergravity environment (2g*) and a normal gravity environment (1g*) within the spatially varying field. The flies had a larger mean speed in 0g* than in 1g*, and smaller in 2g*. The mean square distance travelled by the flies grew more rapidly with time in 0g* than in 1g*, and slower in 2g*. We observed no other clear effects of the magnetic field, up to 16.5 T, on the walks of the flies. We compare the effect of diamagnetically simulated weightlessness with that of weightlessness in an orbiting spacecraft, and identify the cause of the anomalous behaviour as the altered effective gravity.     

Morphological and structural-rheological relationship in epiclon-based polyimide/hydroxypropylcellulose blend systems

Blends of hydroxypropyl cellulose (HPC) in lyotropic phase have been prepared with a new epiclon- based poly(amic acid) (PAA) or its corresponding polyimide (PI). The flow behaviour of their mixed solutions in N,N-dimethylacetamide (DMAc) was investigated by means of shear viscometry and oscillatory shear tests. The effect of composition, temperature and shear rate on the rheological functions reflects the orientation or mobility of the chain segments in the shear field. Specific interactions, such as the hydrogen bonds between PAA and the liquid crystalline component, stabilized the resulted morphology. The band texture, typical for lyotropic HPC solutions, evidencing different intensities and dimensions is observed from atomic force microscopy images in PAA/HPC and PI/HPC blends. The paper pursues some aspects concerning the obtaining of mixed alignment layers used in display devices.