A New Sidelobe Correction Algorithm for Microwave Radiometers: Application to the Envisat Instrument

The antenna temperature measured by a microwave radiometer is converted in brightness temperature (TB) by removing the different contributions that do not come from the main lobe of the antenna. Among them, the Earth contribution in the sidelobes may be significant as for the Environmental Satellite mission due to the antenna position on the platform. In such a case, simple corrections commonly applied on previous altimetry missions are inadequate, and a more accurate correction should be determined. We propose in this paper a new method based on global seasonal tables of contamination. This allows application of an accurate sidelobe correction in space and time in the retrieved TB computation     

成功变革的关键战胜心中的"洞中人"

任何新事物都会遇到抵抗.事情总是这样.每个组织都有一种免疫系统,具备自动袭击任何变化的抗体.     

On the Relation between Morphology and FET Mobility of Poly(3‐alkylthiophene)s at the Polymer/SiO2 and Polymer/Air Interface

The influence of the interface of the dielectric SiO₂ on the performance of bottom‐contact, bottom‐gate poly(3‐alkylthiophene) (P3AT) field‐effect transistors (FETs) is investigated. In particular, the operation of transistors where the active polythiophene layer is directly spin‐coated from chlorobenzene (CB) onto the bare SiO₂ dielectric is compared to those where the active layer is first spin‐coated then laminated via a wet transfer process such that the film/air interface of this film contacts the SiO₂ surface. While an apparent alkyl side‐chain length dependent mobility is observed for films directly spin‐coated onto the SiO₂ dielectric (with mobilities of ≈10^?3 cm² V^?1 s^?1 or less) for laminated films mobilities of 0.14 ± 0.03 cm² V^?1 s^?1 independent of alkyl chain length are recorded. Surface‐sensitive near edge X‐ray absorption fine structure (NEXAFS) spectroscopy measurements indicate a strong out‐of‐plane orientation of the polymer backbone at the original air/film interface while much lower average tilt angles of the polymer backbone are observed at the SiO₂/film interface. A comparison with NEXAFS on crystalline P3AT nanofibers, as well as molecular mechanics and electronic structure calculations on ideal P3AT crystals suggest a close to crystalline polymer organization at the P3AT/air interface of films from CB. These results emphasize the negative influence of wrongly oriented polymer on charge carrier mobility and highlight the potential of the polymer/air interface in achieving excellent “out‐of‐plane” orientation and high FET mobilities.     

Metabolic Syndrome: Updates on Pathophysiology and Management in 2021

Metabolic syndrome (MetS) forms a cluster of metabolic dysregulations including insulin resistance, atherogenic dyslipidemia, central obesity, and hypertension. The pathogenesis of MetS encompasses multiple genetic and acquired entities that fall under the umbrella of insulin resistance and chronic low-grade inflammation. If left untreated, MetS is significantly associated with an increased risk of developing diabetes and cardiovascular diseases (CVDs). Given that CVDs constitute by far the leading cause of morbidity and mortality worldwide, it has become essential to investigate the role played by MetS in this context to reduce the heavy burden of the disease. As such, and while MetS relatively constitutes a novel clinical entity, the extent of research about the disease has been exponentially growing in the past few decades. However, many aspects of this clinical entity are still not completely understood, and many questions remain unanswered to date. In this review, we provide a historical background and highlight the epidemiology of MetS. We also discuss the current and latest knowledge about the histopathology and pathophysiology of the disease. Finally, we summarize the most recent updates about the management and the prevention of this clinical syndrome.     

Synthesis of cadmium and zinc semiconductor compounds from an ionic liquid containing choline chloride and urea

A eutectic mixture of choline chloride and urea (commercially known as Reline) has been used as a medium from which CdS, CdSe, and ZnS thin films have been electrodeposited for the first time. Reline is a conductive room temperature ionic liquid (RTIL) with a wide electrochemical window, which is suitable for use as a medium for electrodeposition. The voltammetric behaviour of the Reline-Cd(II)-sulfur system has been investigated. Thin films of CdS deposited at constant potential were characterized by photocurrent and electrolyte electroabsorbance spectroscopies. Thin films of CdSe and ZnS have also been prepared, and their photocurrent excitation spectra have been measured.     

Precise measurements of the total concentration of atmospheric CO2 and 13CO2/12CO2 isotopic ratio using a lead-salt laser diode spectrometer

We have developed a tunable diode laser spectrometer, called SIMCO (spectrometer for isotopic measurements of CO(2)), for determining the concentrations of (12)CO(2) and (13)CO(2) in atmospheric air, from which the total concentration of CO(2) and the isotopic composition (expressed in delta units) delta(13)CO(2) are calculated. The two concentrations are measured using a pair of lines around 2290.1 cm(-1), by fitting a line profile model, taking into account the confinement narrowing effect to achieve a better accuracy. Using the Allan variance, we have demonstrated (for an integration time of 25 s) a precision of 0.1 ppmv for the total CO(2) concentration and of 0.3[per thousand] for delta(13)CO(2). The performances on atmospheric air have been tested during a 3 days campaign by comparing the SIMCO instrument with a gas chromatograph (GC) for the measurement of the total CO(2) concentration and with an isotopic ratio mass spectrometer (MS) for the isotopic composition. The CO(2) concentration measurements of SIMCO are in very good agreement with the GC data with a mean difference of Delta(CO(2))=0.16+/-1.20 ppmv for a comparison period of 45 h and the linearity of the concentration between the two instruments is also very good (slope of correlation: 0.9996+/-0.0003) over the range between 380 and 415 ppmv. For delta(13)CO(2), the comparison with the MS data shows a larger mean difference of Delta(delta(13)CO(2))=(-1.9+/-1.2)[per thousand], which could be partly related to small residual fluctuations of the overall SIMCO instrument response.     

Growth and characterization of gold catalyzed SiGe nanowires and alternative metal-catalyzed Si nanowires

The growth of semiconductor (SC) nanowires (NW) by CVD using Au-catalyzed VLS process has been widely studied over the past few years. Among others SC, it is possible to grow pure Si or SiGe NW thanks to these techniques. Nevertheless, Au could deteriorate the electric properties of SC and the use of other metal catalysts will be mandatory if NW are to be designed for innovating electronic. First, this article's focus will be on SiGe NW's growth using Au catalyst. The authors managed to grow SiGe NW between 350 and 400°C. Ge concentration (x) in Si1-xGex NW has been successfully varied by modifying the gas flow ratio: R = GeH4/(SiH4 + GeH4). Characterization (by Raman spectroscopy and XRD) revealed concentrations varying from 0.2 to 0.46 on NW grown at 375°C, with R varying from 0.05 to 0.15. Second, the results of Si NW growths by CVD using alternatives catalysts such as platinum-, palladium- and nickel-silicides are presented. This study, carried out on a LPCVD furnace, aimed at defining Si NW growth conditions when using such catalysts. Since the growth temperatures investigated are lower than the eutectic temperatures of these Si-metal alloys, VSS growth is expected and observed. Different temperatures and HCl flow rates have been tested with the aim of minimizing 2D growth which induces an important tapering of the NW. Finally, mechanical characterization of single NW has been carried out using an AFM method developed at the LTM. It consists in measuring the deflection of an AFM tip while performing approach-retract curves at various positions along the length of a cantilevered NW. This approach allows the measurement of as-grown single NW's Young modulus and spring constant, and alleviates uncertainties inherent in single point measurement.     

Segregation in granular materials and the direct measurement of surface forces using atomic force microscopy

It is known that one of the dominant forces controlling the macroscopic motion of particles is the cohesive force due to the presence of liquid bridges between particles. In a mixing process, this force directly impacts the degree of homogeneity achievable by the system. The work presented here provides a quantitative analysis of this relationship through concurrent direct measurements of surface forces due to moisture and blending/segregation experiments. Atomic force microscopy (AFM) was employed to measure the force required to remove the AFM's cantilever from the surface of a glass bead with varying degrees of surface moisture. Corresponding blending/segregation experiments were performed using the same materials and conditions to develop a correlation between the interparticle forces due to the liquid layer and the final state of a mixing process. The extent to which greater moisture content increased the interparticle surface forces was quantified, and it was observed that segregation decreases proportionately to increases in surface forces.