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The gut microbiota plays a key role in cholesterol metabolism, mainly through the reduction of cholesterol to coprostanol. The latter sterol exhibits distinct physicochemical properties linked to its limited absorption in the gut. Few bacteria were reported to reduce cholesterol into coprostanol. Three microbial pathways of coprostanol production were described based on the analysis of reaction intermediates. However, these metabolic pathways and their associated genes remain poorly studied. In this review, we shed light on the microbial metabolic pathways related to coprostanol synthesis. Moreover, we highlight current strategies and future directions to better characterize these microbial enzymes and pathways. [ABSTRACT FROM AUTHOR]

Nanocomposites of metal oxides are useful materials for operation in many energy conversion systems. In this study, such nanocomposites were prepared by oxidation of mixtures of iron and titanium precursor metallic thin films at 520 °C under air atmosphere. The metallic films with different iron percentages were obtained by radio frequency (RF) magnetron sputtering on glass and silicon substrates. The films were characterized by means of X-ray Diffraction (XRD), Raman spectroscopy, UV–Vis spectroscopy, High Resolution Scanning Transmission Electron Microscopy (HRSTEM), Ellipsometry and X-ray Photo-electron Spectroscopy (XPS). The results show that these films present mainly two nanometric phases, namely Fe 2 O 3 and TiO 2 . A phase separation was observed; the film surface was found to be iron rich oxide or clusters of iron rich oxide (Fe x O y , x > y), whereas titanium accumulated deeply in the bulk, forming TiO 2 far below the film surface. A red shift of optical absorption as well as a relatively stable high refractive index (varying between 3.1 and 3.5) over a broad band of optical frequencies was observed for the films containing higher iron initial concentrations. [ABSTRACT FROM AUTHOR]

Structural, optical and dielectric properties of atomic layer deposited HfO 2 were studied in close relation with the bottom electrode nature. We used XRD, HRTEM and AFM to study the internal microstructure and the surface roughness of the films. The HfO 2 /Pt sample shows a mixture of monoclinic and orthorhombic phases whereas the HfO 2 /TiN sample presents few crystallites in orthorhombic structure dispersed in a badly crystallized or amorphous phase. Raman spectroscopy shows that between 100 and 800 cm − 1 , the HfO 2 /Pt device displays 13 Raman-active modes whereas the HfO 2 /TiN device reveals 10 Raman-active modes. Using the UV–Vis reflectance spectra, we expect both direct and indirect electronic transitions with optical band-gap energies of 5.11 and 4.61 eV, respectively. Photoluminescence spectroscopy allows the identification of localized states in the HfO 2 band-gap. PL emission spectra consist of five sub-peaks, centered at around 1.64–1.92 eV, 2.10 eV and 2.33 eV. These energies are close to the trap levels calculated for oxygen vacancies, involved during the film deposition. As the temperature is increased up to 380 °C, an obvious dispersion of the real permittivity takes place in the low frequency domain. This behavior, highly enhanced by the oxygen vacancies mobility, is typical for the electrode polarization process. [ABSTRACT FROM AUTHOR]

The Eubacterium saburreum serine protease inhibitor from the human gut microbiota inhibits the eukaryotic pancreatic elastase associated with acute pancreatitis. Interestingly, the inhibition efficiency and stability are markedly increased by the para-sulphonato-calix[8]arene capped silver nanoparticles. Moreover, this enzyme is distinguishable by its high inhibitory effect at broad pH range between 2–10 and temperatures from 10 to 40 °C, in the presence of para-sulphonato-calix[8]arene capped silver nanoparticles the enzyme remains active even at 70 °C. [ABSTRACT FROM AUTHOR]

Solid electrolytes are important part of all-solid state energy systems that store electrical energy on the chip. They allow a direct incorporation of micro-storage component with simple device architecture while operating at higher temperatures compared to liquid electrolytes. However, solid electrolytes are usually deposited at high temperatures, exceeding the thermal budget of current semiconductor technology. Herein, we report on the synthesis of high performance BaTiO 3 :H films as solid state electrolyte in which we incorporate protons during a room temperature RF sputtering process. Drastic changes occur on chemical, structural and electrical properties of the films when they accommodate highly mobile and reactive protons. BaTiO 3 :H films have well-defined crystalline phases and display an optical bandgap which decreases by increasing the HMR in the sputtering gas. In addition, these films show two relaxation processes. The first, thermally activated with an energy around 0.5 eV, emerges at low temperature due to the proton diffusion within the oxide material. The diffusion of positively charged oxygen vacancies by overcoming an energetic barrier of about 1.1 eV yields to a second relaxation which takes place at relatively high temperature. By using carbon nanowalls as high effective area bottom electrode, we anticipate a large specific capacitance. [ABSTRACT FROM AUTHOR]

Aluminum nitride (AlN) nanostructures are very attractive in various optoelectronic applications such as deep ultraviolet light emitting devices. The fabrication of these AlN nanostructures with good crystalline quality and compatibility in line with other micro-fabrication processes has significant importance for practical applications. AlN films of different thickness values were deposited via DC reactive magnetron sputtering over vertically aligned multiwalled carbon nanotube (CNTs) arrays to obtain AlN/CNTs vertically-aligned shell/core nanostructure assembly. Such hybrid nanostructures were characterized using scanning electron microscope, transmission electron microscope, X-ray diffraction, Raman spectroscopy and time-resolved photoluminescence spectroscope (TR-PL) techniques. The results indicated that AlN/CNTs have a nanorods structure morphology with good AlN crystalline quality. The PL measurements revealed a maximum increase in the luminescent intensity of the exciton band in case of AlN/CNTs with 600 nm thick AlN layer, which is many orders of magnitude higher than that of AlN film produced over silicon substrate. It is anticipated that synergistic effects of CNTs and AlN through an increase in the specific surface area and oxygen-induced defects cause enhancement in the photoluminescence properties, making these hybrid nanostructures a promising candidate for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Describes one of the Partnership's Science Connection programs, the Science Fair Mentoring Program, which was established by the Massachusetts General Hospital (MGH), and the James P. Timilty Middle School. What the program was designed for; Indepth look at the program.

Hybrid thin films based on Hydrocalumite (Ca 2 AlCl layered double hydroxide LDH) and tyrosinaseenzyme have been used for the elaboration of a high sensitive amperometric biosensor detecting polyphenols extracted from green tea. Structural properties of LDH nanomaterials were characterized by X-ray powder diffraction and Infra-Red spectroscopy, confirming its crystalline phase and chemical composition. Ca 2 AlCl-LDHs-thin films were deposited by spin-coating, and studied by atomic force microscopy to obtain information about the surface morphology of this host matrix before and after enzyme's immobilization. Electrochemical study using cyclic voltammetry and chronoamperometry shows good performances of the built-in biosensor with a high sensitivity for polyphenols concentrations ranging from 24 pM to and a limit of detection of 1.2 pM.

As a potential biomarker for the investigation of cancer inflammatory profiles, macrophage mannose receptor (MMR, CD206) is herein selected to develop an immunosensor based on layered double hydroxide (LDH). Like an endocyte C-type lectin receptor, MMR plays an important role in immune homeostasis by scavenging unwanted mannose glycoproteins. It attracts a progressive attention thanks to its particularly high expression within the tumor microenvironment. There is a great of interest to develop an immunosensor based on an antibody specific to MMR for detection of stroma versus tumor cells. In this work, we studied the feasibility of high sensitive MMR cancer Screen Printed Electrode (SPE) immunosensor. Working electrode of commercialized SPE was modified by immobilization of specific antibody (anti-MMR) into thin layer of LDH nanomaterials. Structural, morphological, and surface properties of LDHs were studied by X-Ray diffraction, atomic force microscopy and Infrared spectroscopy in ATR. Cyclic Voltammetry technique was used to study interaction between the human recombinant MMR protein (rHu-MMR, NSO derived) and an immobilized antibody into developed immunosensor. High specific response of -11.72 μA/ng.mL(-1) (with a correlation coefficient of R(2)=0.994 ) were obtained in linear range of 0.05 ng/mL to 10.0 ng/mL of specific recombinant antigen. The limit of detection (LOD) was less than 15.0 pg/mL. From these attractive results, the feasibility of an electrochemical immunosensor for cancer was proved. Additional experiments to study stability and reproducibility the immunosensor should be completed in perspective to use these anti-MMR based immunosensors for sensing human MMR in patient biopsies and sera.

We present a theoretical calculation and experimental results for a waveguiding layer acoustic wave (WLAW). The experimental device is modeled by the finite element method (FEM) for the AlN/ZnO/diamond structure. It was found that the AlN thickness must be at least larger than 3lambda/2 to obtain negligible surface displacement. In the same way, the ZnO thickness for a fixed value of AlN thickness at 2lambda must be larger than lambda/4 to confine the acoustic wave. The electromechanical coupling of the wave presents an optimum around lambda/2 for the ZnO layer thickness. A first experimental AlN/ZnO/diamond device has been developed and shows the WLAW at 412 MHz.