Abstract: The immobilization of biomolecules at screen printed electrodes for biosensing applications is still an open challenge. To enrich the toolbox of bioelectrochemists, graphite screen printed electrodes (G-SPE) were modified with an electropolymerized film of pyrrole-2-carboxilic acid (Py-2-COOH), a pyrrole derivative rich in carboxylic acid functional groups. These functionalities are suitable for the covalent immobilization of biomolecular recognition layers. The electropolymerization was first optimized to obtain stable and conductive polymeric films, comparing two different electrolytes: sodium dodecyl sulphate (SDS) and sodium perchlorate. The G-SPE modified with Py-2-COOH in 0.1 M SDS solution showed the required properties and were further tested. A proof-of-concept study for the development of an impedimetric sensor for perfluorooctanoic acid (PFOA) was carried out using the delipidated human serum albumin (hSA) as bioreceptor. The data interpretation was supported by size exclusion chromatography and small-angle X-ray scattering (SEC-SAXS) analysis of the bioreceptor-target complex and the preliminary results suggest the possibility to further develop this biosensing strategy for toxicological and analytical studies.

Abstract: Gold-sputtered microelectrodes with built-in gold reference and counter electrodes represent a promising platform for the development of disposable DNA sensors. Pretreating gold electrode surfaces and immobilization of DNA thereon is commonly employed in biosensing applications. However, with no scientific or practical guidelines to prepare a DNA sensor using these miniature gold-sputtered microelectrodes, cleaning and immobilization steps need to be systematically optimized and updated. In this work, we present efficient cleaning and modification of miniaturized gold-sputtered microelectrodes with thiolated DNA probes for DNA detection. Additional discussions on subtleties and nuances involved at each stage of pretreating and modifying gold-sputtered microelectrodes are included to present a robust, well-founded protocol. It was evident that the insights on cleaning polycrystalline gold disk electrodes with a benchmark electrode surface for DNA sensors, cannot be transferred to clean these miniature gold-sputtered microelectrodes. Therefore, a comparison between five different cleaning protocols was made to find the optimal one for gold-sputtered microelectrodes. Additionally, two principally different immobilization techniques for gold-sputtered microelectrode modification with thiolated ssDNA were compared i.e., immobilization through passive chemisorption and potential perturbation were compared in terms of thiol-specific attachment and thiol-unspecific adsorption through nitrogenous bases. The hybridization performance of these prepared electrodes was characterized by their sensitive complementary DNA capturing ability, detected by a standard alkaline phosphatase assay. Immobilization through passive chemisorption proved to be efficient in capturing the complementary target DNA with a detection limit of 0.14 nM and sensitivity of 9.38 A M−1 cm2. In general, this work presents a comprehensive understanding of cleaning, modification and performance of gold-sputtered microelectrodes with built-in gold reference and counter electrodes for both fundamental investigations and practical DNA sensing applications.

Abstract: This article delineates the state of the art for several materials used in the harvest, conversion, and storage of energy, and analyzes the challenges to be overcome in the decade ahead for them to reach the market and benefit society. The materials covered have had a special interest in recent years and include perovskites, materials for batteries and supercapacitors, graphene, and materials for hydrogen production and storage. Looking at the common challenges for these different systems, scientists in basic research should carefully consider commercial requirements when designing new materials. These include cost and ease of synthesis, abundance of precursors, recyclability of spent devices, toxicity, and stability. Improvements in these areas deserve more attention, as they can help bridge the gap for these technologies and facilitate the creation of partnerships between academia and industry. These improvements should be pursued in parallel with the design of novel compositions, nanostructures, and devices, which have led most interest during the past decade. Research groups are encouraged to adopt a cross-disciplinary mindset, which may allow more efficient use of existing knowledge and facilitate breakthrough innovation in both basic and applied research of energy-related materials.

Abstract: The use of a Pt electrode coated with a layer of Nafion has been described in previous works as an attractive way to perform the potentiometric detection of hydrogen peroxide. Despite of the attractive features of this approach, the nature of the non-Nernstian response of this system was not properly addressed. In this work, using a mixed potential model, the open circuit potential of the Pt electrode is shown to be under kinetic control of the oxygen reduction reaction (ORR). It is proposed that hydrogen peroxide acts as an oxygenated species that blocks free sites on the Pt surface, interfering with the ORR. Therefore, the effect of the polyelectrolyte coating can be understood in terms of the modulation of the factors that affects the kinetics of the ORR, such as an increase of the H+ concentration, minimization of the effect of the spectator species, etc. Because of the complexity and the lack of models that accurately describe systems with practical applications, this work is not intended to provide a mechanistic but rather a phenomenological view on problem. A general framework to understand the factors that affect the potentiometric response is provided. Experimental evidence showing that the use of polyelectrolyte coatings are a powerful way to control the mixed potential open new ways for the development of robust and simple potentiometric sensors.

Abstract: The use of a photocatalyst (photosensitizer) which produces singlet oxygen instead of enzymes for oxidizing analytes creates opportunities for designing cost-efficient and sensitive photoelectrochemical sensors. We report that perfluoroisopropyl-substituted zinc phthalocyanine (F64PcZn) interacts specifically with a complex phenolic compound, the antibiotic rifampicin (RIF), but not with hydroquinone or another complex phenolic compound, the antibiotic doxycycline. The specificity is imparted by the selective preconcentration of RIF in the photocatalytic layer, as revealed by electrochemical and optical measurements, complemented by molecular modeling that confirms the important role of a hydrophobic cavity formed by the iso-perfluoropropyl groups of the photocatalyst. The preconcentration effect favorably enhances the RIF photoelectrochemical detection limit as well as sensitivity to nanomolar (ppb) concentrations, LOD = 7 nM (6 ppb) and 2.8 A.M-1.cm(-2), respectively. The selectivity to RIF, retained in the photosensitizer layer, is further enhanced by the selective removal of all unretained phenols via simple washing of the electrodes with pure buffer. The utility of the sensor for analyzing municipal wastewater was demonstrated. This first demonstration of enhanced selectivity and sensitivity due to intrinsic interactions of a molecular photocatalyst (photosensitizer) with an analyte, without use of a biorecognition element, may allow the design of related, robust, simple, and viable sensors.

Abstract: Aerosol samples have been collected over the southern bight of the North Sea from an aircraft. In this way, 96 samples were taken for single-particle analysis during 16 flights. Almost 45 000 individual particles were analyzed with electron probe X-ray microanalysis. More than 5000 of these were found to contain significant concentrations of one or more of the heavy metals Cr, Pb, and Zn. With the help of hierarchical, nonhierarchical, and fuzzy clustering techniques, various heavy metal-containing particle types could be identified. Significant differences in abundances were detected in the North Sea heavy metal aerosol, depending on the origin of the air masses. In samples with continental influence 50 times more Zn- and Pb-containing particles were found than in samples with a marine history. For Cr, on the other hand, we found abundances in the marine sector that were one-third of the values for continental sectors. This might point to a rather undefined marine source, which could be the recycling of previously deposited material by reinjection into the atmosphere by sea spray. The highest values for Cr-, Pb-, and Zn-containing particles were always detected under southeastern wind directions.

Abstract: Synchrotron radiation micro-X-ray fluorescence and micro-X-ray diffraction analysis, micro-computed tomography and transmission electron microscopy were used to investigate the microstructure of turbine blades made of a second generation nickel based superalloy CMSX-4 manufactured by investment casting process via Bridgman technique. The dependence of microstructure on process parameters, among others, on the withdrawal rate was analysed. The results set the stage for optimising the microstructure of the blades in terms of their mechanical properties.

Abstract: The experiments conducted are focused on natural organic substances, removal from water in ion-exchange process, ultrafiltration process and ion exchange-ultrafiltration integrated process. The water from the Odra River and model solution were investigated. In treatment processes, various doses of 5 anion-exchange resins as well as polyethersulphone membranes with different cut-offs were used. The efficiency of process was determined by measuring a decrease both in the colour intensity and the UV 254 nm absorbance. The results show that separation efficiency in integrated process depends on resin dose added to water before ultrafiltration and on the membrane cut-off as well. Among the resins tested the most efficient was MIEX (R) resin. The ion-exchange process carried out prior to the ultrafiltration increased, especially for high cut-off membranes, NOM retention and resulted in the decrease of membrane fouling intensity.

Abstract: The growing demand for tools to generate chemical information in decentralized settings is creating a vast range of opportunities for potentiometric sensors, since their combination of robustness, simplicity of operation and cost can hardly be rivalled by any other technique. In previous works, we have shown that the mixed potential of a Pt electrode can be controlled with analytical purposes using a coating of Nafion, thus providing a way to develop a potentiometric biosensor for glucose. Unfortunately, the linear range of this device did not match the relevant clinical range for glucose in blood. This work presents a novel strategy to control the mixed potential that allows the development of a potentiometric biosensor for the direct detection of glucose in whole, undiluted blood without any sample pretreatment. By changing the ionomer, the analytical response can be tuned, shifting the linear range while keeping the sensitivity. Aquivion, a polyelectrolyte from the same family as Nafion, is used to stabilize the mixed potential of a platinized paper-based electrode, to entrap the enzyme and to reduce the interference from negatively charged species. Factors affecting the generation of the signal and the principle of detection are discussed. Optimization of the biosensor composition was achieved with particular focus on the characterization of the linear range and sensitivity. The accurate measurement of blood sugar levels in a single drop of whole blood with excellent recovery is presented.

Abstract: Determination of count losses and pile-up pulse effects in quantitative and qualitative analysis became a vital step in various analyses. Therefore, compensating for counting losses is of importance. These counting losses are due to the pulse pile-up, paralyzable and non-paralyzable system dead time or a combination of these mechanisms. In this work, a new method is suggested for the correction of dead time losses resulting from the above mechanisms. For this purpose, a source code was developed. It was found that the peaking time was an important parameter over system dead time. The method suggested seems to be more effective even at high count rate. (C) 2009 Elsevier B.V. All rights reserved.

Abstract: The Monte Carlo assisted Classical Method (MCCM) consists on a calculation procedure for determining the displacements per atom (dpa) distribution in solid materials. This algorithm allows studying the gamma and electron irradiation damage in different materials. It is based on the electrons elastic scattering classic theories and the use of Monte Carlo simulation for the physical processes involved. The present study deals with the Monte Carlo simulation of electron irradiation effects on YBa2Cu3O7-x (YBCO) slabs using the MCNPX code system. Displacements per atom distributions are obtained through the MCCM for electron irradiation up to 10 MeV. In-depth dpa profiles for electrons and positrons are obtained and analysed. Also, dpa contributions from each atomic specie in the material are calculated. It was found that the dpa distribution is more homogeneous in the material volume when increasing energy of incident electrons. Also, the dpa produced by positrons has no relevance when irradiating with electrons, in contrast with previous similar gamma irradiation studies. All the results are presented and discussed in this contribution. (C) 2011 Elsevier B.V. All rights reserved.

Abstract: Herein, thin-layer potentiometry combined with ion-exchange membranes as barriers for charged interferences is demonstrated for the analytical detection of creatinine (CRE) in undiluted human urine. Briefly, CRE diffuses through an anion-exchange membrane (AEM) from a sample contained in one fluidic compartment to a second reservoir, containing the enzyme CRE deiminase. There, CRE reacts with the enzyme, and the formation of ammonium is dynamically monitored by potentiometric ammonium-selective electrodes. This analytical concept is integrated into a lab-on-a-chip microfluidic cell that allows for a high sample throughput and the operation under stop-flow mode, which allows CRE to passively diffuse across the AEM. Conveniently, positively charged species (i.e., potassium, sodium, and ammonium, among others) are repelled by the AEM and never reach the ammonium-selective electrodes; thus, possible interference in the response can be avoided. As a result, the dynamic potential response of the electrodes is entirely ascribed to the stoichiometric formation of ammonium. The new CRE biosensor exhibits a Nernstian slope, within a linear range of response from 1 to 50 mM CRE concentration. As expected, the response time (15–60 min) primarily depends on the CRE diffusion across the AEM. CRE analysis in urine samples displayed excellent results, without requiring sample pretreatment (before the introduction of the sample in the microfluidic chip) and with high compatibility with development into a potential point-of-care clinical tool. In an attempt to decrease the analysis time, the presented analytical methodology for CRE detection is translated into an all-solid-state platform, in which the enzyme is immobilized on the surface of the ammonium-selective electrode and with the AEM on top. While more work is necessary in this direction, the CRE sensor appears to be promising for CRE analysis in both urine and blood.

Abstract: Cities with resilience to climate change appear to be a vision of the future, but are inevitable to ensure the quality of life for citizens and to avoid an increase in civilian mortality. Urban green infrastructure (UGI), with the focus on vertical green, poses a beneficial mitigation and adaptation strategy for challenges such as climate change through cooling effects on building and street level. This review article explores recent literature regarding this considerable topic and investigates how green walls can be applied to mitigate this problem. Summary tables (see additional information) and figures are presented that can be used by policy makers and researchers to make informed decisions when installing green walls in built-up environments. At last, knowledge gaps are uncovered that need further investigation to exploit the benefits at its best.

Abstract: Brass is a relatively stable alloy but it tends to tarnish over time due to the interaction with the atmosphere. Thus, it is rare to observe centuries-old brass objects untouched by the passing of time. For this reason, the pristine appearance of hundreds of brass sequins in the Enclosed Gardens of Mechelen (reliquary altarpieces produced between 1530 and 1550) is remarkable. In this study, the chemical and metallographic characterization of such unexpectedly well-preserved objects is presented. The results revealed the reason for their stability to be a combination of high-quality materials (i.e. medium Zn content, low impurities) and optimal surface properties (i.e. high homogeneity, low roughness), indicating the high level of expertise of the craftsmen who produced them. Novel fundamental insights on the historical manufacturing method of metallic sequins were also obtained.