Design and realization of transparent solar modules based on luminescent solar concentrators integrating nanostructured photonic crystals

Herein, we present a prototype of a photovoltaic module that combines a luminescent solar concentrator integrating one‐dimensional photonic crystals and in‐plane CuInGaSe₂ (CIGS) solar cells. Highly uniform and wide‐area nanostructured multilayers with photonic crystal properties were deposited by a cost‐efficient and scalable liquid processing amenable to large‐scale fabrication. Their role is to both maximize light absorption in the targeted spectral range, determined by the fluorophore employed, and minimize losses caused by emission at angles within the escape cone of the planar concentrator. From a structural perspective, the porous nature of the layers facilitates the integration with the thermoplastic polymers typically used to encapsulate and seal these modules. Judicious design of the module geometry, as well as of the optical properties of the dielectric mirrors employed, allows optimizing light guiding and hence photovoltaic performance while preserving a great deal of transparency. Optimized in‐plane designs like the one herein proposed are of relevance for building integrated photovoltaics, as ease of fabrication, long‐term stability and improved performance are simultaneously achieved. © 2015 The Authors. Progress in Photovoltaics: Research and Applications published by John Wiley & Sons Ltd.     

Diagnostic Accuracy of CT Texture Analysis in Adrenal Masses: A Systematic Review

Adrenal incidentalomas (AIs) are incidentally discovered adrenal neoplasms. Overt endocrine secretion (glucocorticoids, mineralocorticoids, and catecholamines) and malignancy (primary or metastatic disease) are assessed at baseline evaluation. Size, lipid content, and washout characterise benign AIs (respectively, <4 cm, <10 Hounsfield unit, and rapid release); nonetheless, 30% of adrenal lesions are not correctly indicated. Recently, image-based texture analysis from computed tomography (CT) may be useful to assess the behaviour of indeterminate adrenal lesions. We performed a systematic review to provide the state-of-the-art of texture analysis in patients with AI. We considered 9 papers (from 70 selected), with a median of 125 patients (range 20–356). Histological confirmation was the most used criteria to differentiate benign from the malignant adrenal mass. Unenhanced or contrast-enhanced data were available in all papers; TexRAD and PyRadiomics were the most used software. Four papers analysed the whole volume, and five considered a region of interest. Different texture features were reported, considering first- and second-order statistics. The pooled median area under the ROC curve in all studies was 0.85, depicting a high diagnostic accuracy, up to 93% in differentiating adrenal adenoma from adrenocortical carcinomas. Despite heterogeneous methodology, texture analysis is a promising diagnostic tool in the first assessment of patients with adrenal lesions.     

Campylobacter jejuni loss of culturability in aqueous microcosms and ability to resuscitate in a mouse model

Water is known as one of the main transmission routes of Campylobacter and contributes to increase the number of sporadic infections and outbreaks. Campylobacter jejuni persists in the environment, especially in water, in a viable but non-culturable (VBNC) form that is thought to be a possible cause of water-borne outbreaks. In this study, we evaluated the loss of culturability and viability of 9 C. jejuni strains of clinical origin and one ATCC reference strain when kept at 4 degrees C in artificial sea water (ASW). Culturability was measured as colony-forming units while viability was evaluated by CTC-DAPI double staining and the combined CTC-specific fluorescent antibody technique (CTC-FA). When cultured on Columbia Agar plates, strains exhibited different growth profiles which allowed to classify them into three different groups. Both techniques used to monitor the viability of the bacterial cells showed that C. jejuni strains survived in the VBNC form in the microcosms through a period lasting from 138 to 152 days. The recovery of C. jejuni VBNC forms to culturability, as evidenced by cell division, was obtained by passage in the mouse intestine. Our results indicate that C. jejuni VBNC cells were able to remain in this state for a few months and regain their culturability after in vivo passage depending on their lasting in the VBNC state, which affects the number of respiring bacteria. In fact, the resuscitation was achieved when the number of respiring bacteria became higher than 10(4) cell/ml. Therefore, a relatively high microbial titer of respiring bacteria in the VBNC state seems to be important for the resuscitation and subsequent intestinal colonisation.     

Seasonal variations in total fatty acid composition of muscles and eye sockets of tucunaré (Cichla sp.) from the Brazilian Amazon area

Seasonal variations in total fatty acid compositions of tucunaré, Cichla sp. in the Janauacá Lake of the Amazon basin were determined by GC. Saturated fatty acids (SFAs) were found to be at higher concentrations than monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) in two seasonal periods. Major fatty acids were palmitic (16:0, 48.5–51.6% of total SFA), oleic (18:1ω9, 43.9–50.2% of total MUFA), docosahexaenoic (DHA, 22:6ω3, 13.5–27.9% of total PUFA) and arachidonic acid (AA, 20:4ω6, 16.0–19.6% of total PUFA). Polyunsaturated fatty acids were the most abundant in muscle during the flood period, and more especially fatty acids 22:6ω3 (10%) and 20:4ω6 (7%). There were no significant variations amongst total lipid SFA, MUFA, and PUFA from eye sockets. The ω6 fatty acid percentages were always higher than the ω3 fatty acid percentages in tucunaré, with ω6/ω3 ratios varying between 1.02 and 1.6 in the flood and drought periods.     

Methylene blue adsorption by chemically activated waste pork bones

Bone is an inorganic template containing organic material inside which can be converted into hydroxyapatite‐rich material by pyrolysis. Nowadays, there is a growing research interest in the use of hydroxyapatite, the chemical formula of which is Ca₁₀(PO₄)₆(OH)₂. In the present work, pork bone, an abundant biomass source and food waste, has been converted into structured porous hydroxyapatite by a three‐step process including precharring under mild conditions, chemical activation, and thermal activation. The investigated activating agents were NaOH, KOH, K₂CO₃, H₂SO₄, and H₃PO₄. A thorough investigation of the influence of different activating protocols on the chemical and textural properties of the produced material was carried out by nitrogen adsorption–desorption at 77 K, potentiometric titrations, Fourier transform infrared, and X‐ray diffraction techniques. Chemical activation with NaOH, K₂CO₃, and H₂SO₄ increased the specific surface area up to 53%. H₃PO₄ reduced both surface area and pore volume, and KOH showed little influence on the pore structure. The produced materials were evaluated by methylene blue adsorption tests and showed significant improvement as a result of chemical activation. As a main effect, acid treatment increased methylene blue adsorption kinetics, probably owing to an increase in micropororosity, whereas alkali activation enhanced the adsorption capacity of the resultant biochar.     

Evidences of the Cerium Oxide-Catalysed DPF Regeneration in a Real Diesel Engine Exhaust

The active phase Ce_0.5Pr_0.5O₂ has been loaded on commercial substrates (SiC DPF and cordierite honeycomb monolith) to perform DPF regeneration experiments in the exhaust of a diesel engine. Also, a powder sample has been prepared to carry out soot combustion experiments at laboratory. Experiments performed in the real diesel exhaust demonstrated the catalytic activity of the Ce–Pr mixed oxide for the combustion of soot, lowering the DPF regeneration temperature with regard to a counterpart catalyst-free DPF. The temperature for active regeneration of the Ce_0.5Pr_0.5O₂-containing DPF when the soot content is low is in the range of 500–550 °C. When the Ce_0.5Pr_0.5O₂-containing DPF is saturated with a high amount of soot, pressure drop and soot load at the filter reach equilibrium at around 360 °C under steady state engine operation due to passive regeneration. The uncoated DPF reached this equilibrium at around 440 °C. Comparing results at real exhaust with those at laboratory allow concluding that the Ce_0.5Pr_0.5O₂-catalysed soot combustion in the real exhaust is not based on the NO₂-assisted mechanism but is most likely occurring by the active oxygen-based mechanism.     

Novel poly(vinyl alcohol)-g-poly(hydroxy acid) copolymers: Synthesis and characterization

Poly(vinyl alcohol) (PVA) was reacted with three hydroxy acids (HA), namely D,L-lactic acid (LA), glycolic acid (GA) and D,L-3-hydroxybutyric acid (HB). The graft copolymers obtained were thoroughly characterized by ¹H and ¹³C NMR, FTIR, and DSC. Copolymer compositions were in the range 14–45 mol% HA with average lateral chain lengths in the range 1.1–1.3. The CO stretching band, arising from the lateral polyester chains, presents significant differences from that of pure polyesters. In case of the VALA and VAGA copolymers, carbonyl groups are almost completely interassociated with hydroxyl groups and as a result the carbonyl band presents a single contribution; however, splitting appears in VAHB. The band at about 1735 cm^?1 already observed for Poly(3-hydroxybutyrate) P3HB was reexamined in the light of molecular models for VAHB and the splitting observed was attributed to C–H???OC and to O–H???OC hydrogen bonding. The thermal analysis of copolymers demonstrates that esterification suppresses crystallinity and increases free volume, both accounting for a Tg reduction with regard to PVA. The stronger intermolecular hydrogen bonding interactions found in PVA with the chemically modified PVAs opens an interesting way towards miscibility with polyesters and other polymer systems containing carbonyl groups.     

Assessment of a Cylindrical and a Rectangular Plate Differential Mobility Analyzer for Size Fractionation of Nanoparticles at High-Aerosol Flow Rates

An existing differential mobility analyzer (DMA) of cylindrical electrodes and a novel DMA of rectangular plate electrodes are demonstrated for size fractionation of nanoparticles at high-aerosol flow rates in this work. The two DMAs are capable of delivering monodisperse size selected nanoparticles (SMPS σ_g < 1.1) at gas flow rates ranging from 200 slm to 500 slm. At an aerosol flow rate of 200 slm, the maximum attainable particle mean size is of about 20 nm for the cylindrical DMA and of nearly 50 nm for the rectangular plate DMA. The number concentration of the monodisperse nanoparticles delivered by the high-flow DMAs spans from 10⁴ cm^?3 to 10⁶ cm^?3 depending upon the particle mean size and particle size dispersion.

Copyright 2014 American Association for Aerosol Research     

Effect of CeO2 and La2O3 on the Activity of CeO2−La2O3/Al2O3-Supported Pd Catalysts for Steam Reforming of Methane

The effect of the addition of CeO₂ or La₂O₃ on the surface properties and catalytic behaviors of Al₂O₃-supported Pd catalysts was studied in the steam reforming of methane. The FTIR spectroscopy of adsorbed CO and the Pd dispersion suggest the partial coverage of Pd⁰ by ceria or lanthana species. This could lead to the formation of an adduct MPd _x O (M = Ce or La) at the surface of the metal crystallites. The addition of ceria or lanthana resulted in an increase of the turnover rate and specific rate for steam reforming of methane. One possible explanation if that the Pd⁰*Pd^δ+O–M interfacial species (M = Ce or La) are oxidized by H₂O or CO₂, promoting the O* transfer to the metal surface. This could facilitate the removal of C* species from the metal surface, resulting in the increase of specific reaction rate and increase of the accessibility of CH₄ to metal active sites.     

Mechanical and fracture behavior of an artificially ultraviolet‐irradiated poly(ethylene‐carbon monoxide) copolymer

In this work, 1 wt % carbon monoxide (CO) poly(ethylene‐carbon monoxide) (ECO) copolymer sheets were artificially exposed to ultraviolet (UV) light with a power density of 3 mW/cm² for up to 130 h. A thorough mechanical characterization of the irradiated material was conducted, in which both the stress–strain data and the values of the quasistatic crack initiation and growth toughness were measured and correlated with companion uniaxial tensile tests and single‐edge‐notched fracture tests. Average values of the elastic modulus, failure strain, and failure stress were determined from the tensile tests. The full‐field optical technique of digital image correlation was used to quantify in‐plane deformation (displacements and displacement gradients) during the fracture experiments and to extract values of the crack initiation and growth fracture toughness. The elastic modulus increased monotonically with UV irradiation for the exposure times used in this investigation. In addition, for low irradiation times of less than 5 h, both the failure strain and failure stress of ECO decreased, and this caused a corresponding decrease in the crack initiation and growth toughness. However, for longer irradiation times, the failure strain remained almost invariable, whereas the failure stress increased by about 25% over that of unirradiated ECO. As a result, for longer irradiation times (>5 h), 1 wt % CO ECO became not only stiffer but also stronger and tougher, as quantified by companion fracture experiments. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 139–148, 2004