Analysis of the Rotation Bending Test Method and Characterization of Unidirectional Carbon Fiber-Reinforced Polycarbonate Tapes at Processing Temperatures.

Bending is one of the dominant material deformation mechanisms that occurs during the forming process of unidirectional (UD) thermoplastic tapes. Experimental characterization of the bending behavior at processing temperatures is crucial to obtaining close-to-reality data sets for process analysis or material modeling for process simulation. The main purpose of this study is to characterize to a high degree of accuracy the temperature-dependent bending behavior of single and multi-ply specimens of carbon fiber-reinforced polycarbonate (PC/CF) UD tapes at processing temperatures, which implies a molten state of the thermoplastic matrix. The application of the rotation bending test using a customized fixture may come with systematic deviations in the measured moment that result from a pivot offset or an effective clearance that is unknown under realistic test conditions. The present research analyzes these effects with analytical methods, experimental investigations, and simulations using a finite element model. In this context, a compensation method for the toe-in effect is evaluated. With this approach, we were able to obtain reliable data and characterize the bending resistance within the desired processing window. The data reveal a major drop in bending resistance between 200 °C and 250 °C and a less significant decrease between 250 °C and 300 °C. Analysis of the thickness-normalized bending resistances indicates a non-linear relationship between specimen thickness and measured moment but an increasing shear-dominated characteristic at higher temperatures.

Interface Characterization of Consolidated PPGF Tapes on PPGF Mat Material.

Laminated composites with thermoset matrices are already well established in major engineering fields like automotive and aviation. The primary drawbacks of such thermoset-based composites are the high cycle times required during manufacturing and their limited potential for recycling. Providing an alternative to thermoset-based composites, thermoplastic matrix materials gained more and more momentum by addressing these previously mentioned drawbacks. The preferred manufacturing technique for these materials employs fiber-reinforced thermoplastic tapes consolidated and formed together with a compatible substrate. The most critical aspect for all these applications is the stress or load transfer between the thermoplastic tapes and the substrate. If the interface is too weak and fails prior to the substrate or tape, a high amount of theoretical mechanical performance is lost. The presented research investigates the influence of variations in manufacturing parameters, within the industrially relevant process window, on the interface strength of the final composite. The investigated composite material consists of PPGF UD tapes consolidated on a PPGF mat substrate. In particular, the influence of the consolidation parameters of pressure, temperature, and time are of special interest. The results of this work reveal a 400% increase in the measured mean strain energy release rate upon increasing the consolidation time from 60 s to 120 s at a consolidation temperature of 230 °C and a pressure of one bar. In contrast to this, an increase in the consolidation pressure, at constant temperature and time, leads to a minor improvement in the GC value of 20%. For testing and characterizing the corresponding interface properties, a mandrel peel testing setup was employed.

Synovial Extracellular Vesicles: Structure and Role in Synovial Fluid Tribological Performances.

The quality of the lubricant between cartilaginous joint surfaces impacts the joint's mechanistic properties. In this study, we define the biochemical, ultrastructural, and tribological signatures of synovial fluids (SF) from patients with degenerative (osteoarthritis-OA) or inflammatory (rheumatoid arthritis-RA) joint pathologies in comparison with SF from healthy subjects. Phospholipid (PL) concentration in SF increased in pathological contexts, but the proportion PL relative to the overall lipids decreased. Subtle changes in PL chain composition were attributed to the inflammatory state. Transmission electron microscopy showed the occurrence of large multilamellar synovial extracellular vesicles (EV) filled with glycoprotein gel in healthy subjects. Synovial extracellular vesicle structure was altered in SF from OA and RA patients. RA samples systematically showed lower viscosity than healthy samples under a hydrodynamic lubricating regimen whereas OA samples showed higher viscosity. In turn, under a boundary regimen, cartilage surfaces in both pathological situations showed high wear and friction coefficients. Thus, we found a difference in the biochemical, tribological, and ultrastructural properties of synovial fluid in healthy people and patients with osteoarthritis and arthritis of the joints, and that large, multilamellar vesicles are essential for good boundary lubrication by ensuring a ball-bearing effect and limiting the destruction of lipid layers at the cartilage surface.

Selective area growth of AlGaN nanopyramids by conventional and pulsed MOVPE.

Planar UV-C light emitting diodes still suffer from low efficiency, mainly due to substrate crystalline quality, p doped conductivity and extraction efficiency. One possible way to overcome partly these issues is to realize the whole UV structure on AlGaN pyramids by selective area growth in order to benefit from the advantages of such structures, i.e. the dislocation filtering and the semi polar planes. We present here a detailed study about the epitaxy of AlGaN nano-sized pyramids by metal organic vapor phase epitaxy on patterned templates presenting different holes apertures and pitches as 1.5 µm and 4 µm or 100 nm and 250 nm respectively. While increasing the Al content, their height decreases while the thickness of the deposition on the mask increases whatever the design of the mask. Those changes of the pyramid shapes and deposition are directly linked to the properties of Al adatoms, i.e. low Al diffusion length. Using the conventional growth mode for the epitaxy of those pyramids did not permit the incorporation of Al from the base of the pyramids to their truncated apex. Its presence was concentrated on the edges and top of the pyramids. On the contrary, a pulsed growth mode, coupled with a strongly reduced pitch, allowed an incorporation of Al since the base of the nanopyramid, and a decrease of the deposition height on the mask. These results can be explained by the desorption of Ga species, due to the presence of H2 in the reactor chamber during the step without the metal precursors, leading to a higher Al/Ga ratio. It is even enhanced inside the holes by the reduced pitch.

Supported Porous Nanostructures Developed by Plasma Processing of Metal Phthalocyanines and Porphyrins.

The large area scalable fabrication of supported porous metal and metal oxide nanomaterials is acknowledged as one of the greatest challenges for their eventual implementation in on-device applications. In this work, we will present a comprehensive revision and the latest results regarding the pioneering use of commercially available metal phthalocyanines and porphyrins as solid precursors for the plasma-assisted deposition of porous metal and metal oxide films and three-dimensional nanostructures (hierarchical nanowires and nanotubes). The most advanced features of this method relay on its ample general character from the point of view of the porous material composition and microstructure, mild deposition and processing temperature and energy constrictions and, finally, its straightforward compatibility with the direct deposition of the porous nanomaterials on processable substrates and device-architectures. Thus, taking advantage of the variety in the composition of commercially available metal porphyrins and phthalocyanines, we present the development of metal and metal oxides layers including Pt, CuO, Fe2O3, TiO2, and ZnO with morphologies ranging from nanoparticles to nanocolumnar films. In addition, we combine this method with the fabrication by low-pressure vapor transport of single-crystalline organic nanowires for the formation of hierarchical hybrid organic@metal/metal-oxide and @metal/metal-oxide nanotubes. We carry out a thorough characterization of the films and nanowires using SEM, TEM, FIB 3D, and electron tomography. The latest two techniques are revealed as critical for the elucidation of the inner porosity of the layers.

Transfer of the Cystic Fibrosis Transmembrane Conductance Regulator to Human Cystic Fibrosis Cells Mediated by Extracellular Vesicles.

Cystic fibrosis (CF) is a genetic disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene, resulting in a deficiency in chloride channel activity. In this study, extracellular vesicles (EVs), microvesicles, and exosomes were used as vehicles to deliver exogenous CFTR glycoprotein and its encoding mRNA (mRNA(GFP-CFTR)) to CF cells to correct the CFTR chloride channel function. We isolated microvesicles and exosomes from the culture medium of CFTR-positive Calu-3 cells, or from A549 cells transduced with an adenoviral vector overexpressing a GFP-tagged CFTR (GFP-CFTR). Both microvesicles and exosomes had the capacity to package and deliver the GFP-CFTR glycoprotein and mRNA(GFP-CFTR) to target cells in a dose-dependent manner. Homologous versus heterologous EV-to-cell transfer was studied, and it appeared that the cellular uptake of EVs was significantly more efficient in homologous transfer. The incubation of CF15 cells, a nasal epithelial cell line homozygous for the ΔF508 CFTR mutation, with microvesicles or exosomes loaded with GFP-CFTR resulted in the correction of the CFTR function in CF cells in a dose-dependent manner. A time-course analysis of EV-transduced CF cells suggested that CFTR transferred as mature glycoprotein was responsible for the CFTR-associated channel activity detected at early times posttransduction, whereas GFP-CFTR translated from exogenous mRNA(GFP-CFTR) was responsible for the CFTR function at later times. Collectively, this study showed the potential application of microvesicles and exosomes as vectors for CFTR transfer and functional correction of the genetic defect in human CF cells.

Ultrastructural analysis of healthy synovial fluids in three mammalian species.

A better knowledge of synovial fluid (SF) ultrastructure is required to further understand normal joint lubrication and metabolism. The aim of the present study was to elucidate SF structural features in healthy joints from three mammalian species of different size compared with features in biomimetic SF. High-resolution structural analysis was performed using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) and environmental SEM/wet scanning transmission electron microscopy mode complemented by TEM and SEM cryogenic methods. Laser-scanning confocal microscopy (LCM) was used to locate the main components of SF with respect to its ultrastructural organization. The present study showed that the ultrastructure of healthy SF is built from a network of vesicles with a size range from 100 to a few hundred nanometers. A multilayered organization of the vesicle membranes was observed with a thickness of about 5 nm. LCM study of biological SF compared with synthetic SF showed that the microvesicles consist of a lipid-based membrane enveloping a glycoprotein gel. Thus, healthy SF has a discontinuous ultrastructure based on a complex network of microvesicles. This finding offers novel perspectives for the diagnosis and treatment of synovial joint diseases.

Hybrid technology with microwaves, electron beams and catalysts for VOCs removals.

This work presents a hybrid technology and two hybrid installations (HI-1 and HI-2) for volatile organic compounds (VOCs) removal using successive or simultaneous microwave (MW) irradiation, electron beam (EB) irradiation, and catalytic oxidation. HI-1 is designed for successive EB and MW irradiation with two distinct reactors, both containing a catalyst inside. HI-2 is designed for simultaneous EB and MW irradiation in the same reactor containing a catalyst. Real synergistic effects between non-thermal plasma (NTP) and catalysis were obtained by introducing the catalyst into the irradiation zone, i.e. into the MW reactor EB reactor or into a reactor in which both EB and MW are injected.

Combined microwave and electron beam exposure facilities for medical studies and applications.

The paper presents two radiation exposure facilities (REFs) which permit separate and simultaneous irradiation with microwaves (MW) of 2.45 GHz and electron beams (EB) of 6.23 MeV for malignant melanoma (MM) cell investigations, in vitro (MW+EB-REF-vitro) and in vivo (MW+EB-REF-vivo). The REFs are specifically designed for the following medical studies: 1) The effects of separate and combined (successive and simultaneous) MW and EB irradiation on the B16F10 mouse--MM cell cultures without/with drugs incubation, 2) The effects of separate and combined MW and EB irradiation on human blood components irradiated in samples of integral blood from healthy donors and from donors with MM; 3) The effects of separate and combined MW and EB whole body irradiation on the C57 BL/6 mice bearing MM without/with drugs administration. Several representative results obtained by experiments with REFs in vitro and in vivo are discussed. The most important conclusion of the experimental results is that low dose-total body MW+EB irradiation combined with drugs administration could present a valuable potential for an advanced study in malignant melanoma therapy.

Combined effects of microwaves, electron beams and polyfunctional monomers on rubber vulcanization.

This paper presents comparative results obtained by conventional vulcanization with benzoyl peroxide (CV-BP), separate electron beam vulcanization (EB-V) and simultaneous electron beam and microwave vulcanization (EB+MW-V) applied to two kind of rubber samples: EVA (ethylene vinyl acetate) rubber-sample (EVA-sample) and EPDM (ethylene-propylene terpolymer) rubber-sample (EPDM-sample). The EVA-samples contain 61.54% EVA Elvax 260, 30.77% carbon black, 1.85% TAC (triallylcyanurate) polyfunctional monomer and 5.84% filler (zinc oxide, stearic acid, polyethylene glycol and antioxidant). The EPDM-samples contain 61.54% EPDM Nordel 4760, 30.77% carbon black, 1.85% TMPT (trimethylopropane trimethacrylate) polyfunctional monomer and 5.84% filler (zinc oxide, stearic acid, polyethylene glycol and antioxidant). The rubber samples designed for different vulcanization methods were obtained from raw rubber mixtures, as compressed sheets of 2 mm in the polyethylene foils to minimize oxidation. For EB and EB + MW treatments the sheets were cut in rectangular shape 0.15 x 0.15 m2. The physical properties of samples obtained by CV-BP EV-Vand EB + MW-V methods were evaluated by measuring the tearing strength, residual elongation, elongation at break, tensile strength, 300% modulus, 100% modulus, elasticity and hardness. The obtained results demonstrate an improvement of rubber several properties obtained by EB and EB + MW processing as compared to classical procedure using benzoyl peroxide.

Cell investigations simultaneously with exposure to 2.45 GHz microwaves.

The paper presents two microwave (MW) exposure systems (MWESs) that permit observations and measurements on cell cultures during their exposure to MW of 2.45 GHz: MWES-1 and MWES-2. MWES-1 is designed for the measurement of the cell membrane fluorescence anisotropies (MFA) simultaneously with MW exposure. MWES-2 is designed for the cells culture exploration under an inverted microscope before, during and after MW exposure. MWES-1 consists mainly of a 2.45 GHz microwave generator (MWG-2.45 GHz-SAIREM) of 0-25 W, equipped with forward power and reflected power displaying, and an adjustable coaxial antenna immersed directly into the cuvette with the cells-suspension of a Spex type spectrofluorometer. The MW effect on membrane fluidity of B16F10 malignant melanoma (B16F10-MM) cells in suspension were investigated with MWES-1, by MFA measurements. We observed a MW induced transition temperature (ITT) rising strongly during the MW exposure as compared with ITT obtained by classical heating (CH). The MWES-2 consists of the MWG-2.45 GHz-SAIREM generator and a rectangular waveguide applicator with traveling wave placed between the condenser and the objective of a Zeiss Axiovert 200 microscope, equipped with a fluorescence device and image acquisition. The MW effects on shape and apoptosis of the B16F10-MM cells were investigate with MWES-2. The B16F10-MM cells exhibited visible shape changes during MW exposure up to 37 degrees C. The MW exposure induced cells apoptosis/necrosis in several seconds after that MW are applied, beginning with SAR = 1.5 W/sample, compared to CH controls exposed at the same temperature dynamics.

Vaccine preparation by radiation processing.

A new radiation biotechnology for the acquirement of a commercial vaccine, designed for prophylaxis of ruminant infectious pododermatitis (IP), produced by gram negative bacteria Fusobacterium necrophorum (F.n.), is presented. Two different processes for preparing F.n. vaccine are used: a) the inactivation of F.n. bacteria exotoxins by microwave (MW) or/and electron beams (EB) irradiation; b) the isolation of exotoxins from F.n. cultures irradiated with MW or/and EB and the inactivation of isolated F.n. exotoxins with formalin. The EB irradiation of F.n. cultures produced simultaneously with the cells viability decrease an increasing of exotoxin quantity released in the culture supranatant as compared with classical methods. The MW irradiation is able to reduce the cells viability to zero but without an increase of exotoxin quantity in cultures supranatant. Instead of this MW irradiation, for certain conditions, is able to induce an important stimulation degree of the F.n. proliferation in cultures, from two to three log10. Two vaccine types were prepared: A1 vaccine that contains whole cell culture irradiated with MW/EB and A2 vaccine that contains cell-free culture supernatant of an MW/EB irradiated F.n. strain producing exotoxins. Also, other two vaccines are prepared: B1 and B2 that contain the same materials as A1 and A2 respectively, but without using MW/EB exposure. The vaccine efficiency is tested in ruminant farms in which IP evolves. It is expected that this new vaccine to offer a better protection, more than 60%, which is the best presently obtained result in ruminant farms.

SO2 and NOx removal by microwave and electron beam processing.

This work presents a method and a semi-pilot scale installation (SPSI) for the simultaneous SO2 and NOx removal by separate and combined microwave (MW) and electron beam (EB) irradiation. The SPSI consists mainly of the following units: a gaseous mixture preparation system (GMPS), a microwave source (MS) of 2.45 GHz and 4.2 kW maximum output power an electron beam source (EBS) of 1.8 MeVand 10.8 kW maximum output power and a multimode rectangular cavity (MRC), used as reaction chamber in which are injected both MW and EB fields. The most important parameters for high SO2 removal efficiencies obtained by MW technology are water and ammonia concentration, the gaseous mixture temperature during irradiation process and MW power level. The most important parameter for high NOx removal efficiency obtained by MW technology is MW power level. The removal efficiencies obtained by MW processing were up to 95% for SO2 and up to 55% for NOx. The additional use of EB irradiation to MW exposure strongly increases NOx removal efficiencies in comparison with MW exposure only, up to 95%, simultaneously providing very high values for the SO2 removal efficiency, near 100%.