A comprehensive review of solar facades. Transparent and translucent solar facades

In the first paper of a series of two publications entitled “A comprehensive review of solar facades. Opaque solar facades” an exhaustive review of scientific studies carried out during the last decade on opaque solar facades was proposed. The paper dealt with facades that absorb and reflect the incident solar radiation but cannot transfer directly solar heat gain into the building. This article offers a complementary survey of studies conducted during the same period of time on transparent and translucent solar facades, highlighting the categories of ventilated facades and semi-transparent building-integrated photovoltaic facades.     

Reduction reactions applied for synthesizing different nano-structured materials

Different materials have been synthesized by alternative routes: nitrates thermal decomposition to prepare oxide or co-formed oxides and reduction by hydrogen or graphite to obtain mixed oxides, composites or alloys. These chemical-based synthesis routes are described and thermodynamics studies and kinetics data are presented to support its feasibility. In addition, selective reduction reactions have been applied to successfully produce metal/ceramic composites, and alloys. Structural characterization has been carried out by X-ray Diffraction and, more extensively, Transmission Electron Microscopy operating in conventional diffraction contrast (CTEM) and high-resolution mode (HRTEM), indicated the possibility of obtaining oxide and alloy crystals of sizes ranging between 20 and 40 nm.     

Toxicological assessment of indium nitrate on aquatic organisms and investigation of the effects on the PLHC-1 fish cell line

Indium nitrate is mainly used as a semiconductor in batteries, for plating and other chemical and medical applications. There is a lack of available information about the adverse effects of indium compounds on aquatic organisms. Therefore, the toxic effects on systems from four trophic levels of the aquatic ecosystem were investigated. Firstly, the bacterium Vibrio fischeri, the alga Chlorella vulgaris and the cladoceran Daphnia magna were used in the toxicological evaluation of indium nitrate. The most sensitive model was V. fischeri, with a NOAEL of 0.02 and an EC(50) of 0.04 mM at 15 min. Although indium nitrate should be classified as harmful to aquatic organisms, it is not expected to represent acute risk to the aquatic biota. Secondly, PLHC-1 fish cell line was employed to investigate the effects and mechanisms of toxicity. Although protein content, neutral red uptake, methylthiazol metabolization, lysosomal function and acetylcholinesterase activity were reduced in cells, stimulations were observed for metallothionein levels and succinate dehydrogenase and glucose-6-phosphate dehydrogenase activities. No changes were observed in ethoxyresorufin-O-deethylase activity. To clarify the main events in PLHC-1 cell death induced by indium nitrate, nine modulators were applied. They were related to oxidative stress (alpha-tocopherol succinate, mannitol and sodium benzoate), disruption of calcium homeostasis (BAPTA-AM and EGTA), thiol protection (1,4-dithiotreitol), iron chelation (deferoxiamine) or regulation of glutathione levels (2-oxothiazolidine-4-carboxylic acid and malic acid diethyl ester). The main morphological alterations were hydropic degeneration and loss of cells. At least, in partly, toxicity seems to be mediated by oxidative stress, and particularly by NADPH-dependent lipid peroxidation.     

Solvent Extraction: Kinetic Study of Major and Minor Compounds

The effects of temperature and contact time on lipid extraction from sunflower collets was investigated in a batch extractor with hexane as solvent. The total removed material varied in quantity and composition due to changes in temperature and contact time. Higher temperatures enhanced oil extraction as well as increased the tocopherol and phospholipid contents of the oil. The kinetic data for triglycerols, phospholipid and tocopherols extraction were interpreted by using an equation that considers extraction as the sum of two components: diffusion and washing. Effective diffusion coefficients for oil, tocopherols and phospholipid at different temperatures were determined. Control of temperature and contact time are essential to obtain good quality oil and reduce refining costs. Extraction at 60 °C and short contact times (30 min) obtained high oil yield (98%) accompanied by significant tocopherol extraction (>99%) and reduced phospholipid extraction (66%).     

Detection of Listeria monocytogenes in white cheese by polymerase chain reaction (PCR)

The polymerase chain reaction, known as PCR, is a method to replicate thousands of times within a few hours and in vitro, small amounts of DNA. The application of rapid and sensitive methods to detect Listeria monocytogenes in cheese samples, allow a better microbiological control of the production process. PCR was applied to 30 samples of of white cheese, from Valencia, Carabobo State. It was detected PCR specificity and sensitivity by using the control strain Listeria monocytogenes 446. DNA extraction according to the methodology described by Torres et al., Molecular weight marker 100 base pairs. Were used: four primers hlyA gene of listeriolysin O; L1/U1 primers for 938 bp band and LF/LR 750 bp band hlyA gene. Epilnfo Statistical V6 to match observations in gels, by Kappa coefficient (K). Results: 8 out of 30 cheese samples analyzed showed presumptive growth of Listeria spp in PALCAM Agar. Two of the samples not belonged to the genus Listeria, in the 6 remaining sample confirmation tests showed that: 2 were L. monocytogenes, 3 L. ivanovii and 1 L. seeligeri. In PCR 2 samples were positive for L. monocytogenes by amplify the 938 bp band for Listeria and 750 bp band for the species monocytogenes. We concluded that PCR was highly specific and sensitive to L. monocytogenes, taking advantage of PALCAM agar to detect the presence of the pathogen specifies a relatively short time.     

Are Drop-Impact Phenomena Described by Rayleigh-Taylor or Kelvin-Helmholtz Theory?

Drop impact, spreading, fingering, and snap-off are important inmany engineering applications such as spray drying, industrial painting, environmentally friendly combustion, inkjet printing, materials processing, fire suppression, and pharmaceutical coating. Controlling drop-impact instability is crucial to designing optimized systems for the aforementioned applications. Classical Rayleigh-Taylor (RT) theory has been widely used to analyze fingering where instabilities at the leading edge of the toroidal ring form fingers that may ultimately snap off to form small droplets. In this study, we demonstrate the inapplicability of RT theory, in particular because it fails to explain the stable regimes observed under conditions of low air density and the instabilities observed when a drop impacts a pool of equal-density fluid. Specifically, finger instability decreases with decreasing air density, whereas the RT theory suggests that instability should remain unchanged. Moreover, experiments show that fingers form upon impact of a dyed water drop with a water pool, whereas the RT theory predicts noinstability when the densities of the two interacting fluids are equal. Experimental evidence is instead consistent with instability predictions made using the shear-driven Kelvin-Helmholtz theory.     

Mathematical model for the study and design of a solar dish collector with cavity receiver for its application in Stirling engines

This paper presents a mathematical model that allows representing the optical behavior of a solar parabolic dish concentrator and the thermal performance of a cavity receiver. A procedure and a graphical method for the design of dish/cavity systems are proposed. A parametric study of the main geometric variables is performed and the influence of climate variables on the thermal behavior of the system coupled to a Stirling engine is analyzed. The model considers errors of solar collector, intercept factor, reflected and emitted radiation, conduction, and convection heat losses. For the validation of the model, the results obtained were compared with theoretical and experimental results reported in the literature. The calculation of the radiation losses, emitted and reflected from the receiver presented errors of up to 14%, and the average error for the rest of the thermal losses, interception factor and the absorber??s temperature, was less than 3%. These results show that the proposed model can be used with sufficient certainty to design and optimize solar dish collectors with cavity receivers.     

Key role of microbial characteristics on the performance of VOC biodegradation in two-liquid phase bioreactors

Despite being studied for over 20 years, little is known about the mechanisms underlying the treatment of volatile organic compounds (VOCs) from industrial off-gases in two-liquid phase bioreactors (TLPBs). Recent reports have highlighted a significant mismatch between the high abiotic mass transfer capacity of TLPBs and the low VOC biodegradation rates sometimes recorded, which suggests that a process limitation might also be found in the microbiology of the process. Therefore, this study was conducted to assess the key role of microbial characteristics on the performance of VOC biodegradation in a TLPB using three different hexane degrading consortia. When silicone oil 200 cSt (SO200) was added to the systems, the steady state hexane elimination capacities (ECs) increased by a factor of 8.7 and 16.3 for Consortium A (hydrophilic microorganisms) and B (100% hydrophobic microorganisms), respectively. In the presence of SO200, Consortium C supported a first steady state with a 2-fold increase in ECs followed by a 16-fold EC increase after a hydrophobicity shift (to 100% hydrophobic microorganisms), compared to the system deprived of SO200. This work revealed that cell hydrophobicity can play a key role in the successful performance of TLPBs, and to the best of our knowledge, this is the first report on hydrophobic VOC treatment with exclusive VOC uptake within a nonbioavailable non aqueous phase. Finally, an independent set of experiments showed that metabolite accumulation can also severely inhibit TLPB performance despite the presence of SO200.     

The chemistry of the sulfur-gold interface: in search of a unified model

Over the last three decades, self-assembled molecular films on solid surfaces have attracted widespread interest as an intellectual and technological challenge to chemists, physicists, materials scientists, and biologists. A variety of technological applications of nanotechnology rely on the possibility of controlling topological, chemical, and functional features at the molecular level. Self-assembled monolayers (SAMs) composed of chemisorbed species represent fundamental building blocks for creating complex structures by a bottom-up approach. These materials take advantage of the flexibility of organic and supramolecular chemistry to generate synthetic surfaces with well-defined chemical and physical properties. These films already serve as structural or functional parts of sensors, biosensors, drug-delivery systems, molecular electronic devices, protecting capping for nanostructures, and coatings for corrosion protection and tribological applications. Thiol SAMs on gold are the most popular molecular films because the resulting oxide-free, clean, flat surfaces can be easily modified both in the gas phase and in liquid media under ambient conditions. In particular, researchers have extensively studied SAMs on Au(111) because they serve as model systems to understand the basic aspects of the self-assembly of organic molecules on well-defined metal surfaces. Also, great interest has arisen in the surface structure of thiol-capped gold nanoparticles (AuNPs) because of simple synthesis methods that produce highly monodisperse particles with controllable size and a high surface/volume ratio. These features make AuNPs very attractive for technological applications in fields ranging from medicine to heterogeneous catalysis. In many applications, the structure and chemistry of the sulfur-gold interface become crucial since they control the system properties. Therefore, many researchers have focused on understanding of the nature of this interface on both planar and nanoparticle thiol-covered surfaces. However, despite the considerable theoretical and experimental efforts made using various sophisticated techniques, the structure and chemical composition of the sulfur-gold interface at the atomic level remains elusive. In particular, the search for a unified model of the chemistry of the S-Au interface illustrates the difficulty of determining the surface chemistry at the nanoscale. This Account provides a state-of-the-art analysis of this problem and raises some questions that deserve further investigation.