Search

Unitized regenerative proton exchange membrane fuel cell (URPEMFC) as a self-sufficient hydrogen energy system offers a unique proposition for achieving a net zero emissions future. The system combines the operation of water. Due to the design parameters and operating conditions of URPEMFC, the potential cycling from the mode switching, high temperature, humidified environment and the long exposure of metallic components to hydrogen are the primary factors causing degradation to the system. Consequently, the conventional graphite bipolar plate (BP) suffers heavily under such an environment while giving rise to alternative metallic base materials, such as titanium, stainless steel, and aluminum. Various surface treatment and coating methods are currently under investigation to provide the required corrosion resistance while maintaining feasible manufacturing process and cost. This paper presents an overview into the degradation phenomena of URPEMFC that contributes to the corrosion of BP that is affecting the performance and future commercialization of the system. The operating condition of the system is summarized in terms of fuel cells and water electrolyzers respectively, along with the integration of both operations as a system. Next, the paper outlines the degradation phenomena observed on BP and the behavior of various materials under such conditions. The performances of various base and coating materials have been compiled as have characterization methods that are useful in measuring corrosion resistance. This paper aims to provide a better understanding on the overall degradation of BP in URPEMFC and overview of various material choices to identify the optimal corrosion mitigation solution. [Display omitted] • Breakdown of the URPEMFC operating parameters from the respective operation modes. • System design approaches allowing integration of fuel cell and electrolyzer modes. • Identification of the main degradation mechanism on the BP. • Tabulated data of various base materials and coatings performance. • Discussion of current experimental and modeling methods for corrosion resistance characterization. [ABSTRACT FROM AUTHOR]

Knowledge driven materials and component design is key for improving the performance of Li-ion batteries and solving the remaining hurdles for next-generation battery concepts like all-solid-state batteries. While the spatial and time dependent distribution of Li would help elucidating performance bottlenecks and degradation phenomena, only a few analysis techniques are available, due to the unique nature of Li, especially as Li+-ion. In fact, only two non-destructive techniques with good time resolution can combine spatial information with absolute quantification of Li, one being Neutron Depth Profiling (NDP), the other Ion-Beam-Analysis (IBA). While both exploit nuclear processes, the information gained is complementary. NDP provides high depth resolution, but only limited lateral resolution, whereas IBA has high lateral, but only limited depth resolution. In this study, we benchmark both techniques for the first time using a set of Li-battery test-samples and show the strengths and synergies of both techniques. The derived information regarding the depth dependent Li-concentration is then used to validate a microstructure resolved continuum model of charge, discharge, and relaxation behavior of the cells and electro-chemical analysis. This fundamental work demonstrates a new route to optimize Li batteries on material and component level by combining advanced characterization and digital twin modelling. • LLZO + LCO ASBs analyzed using MeV Ion-Beam-Analysis + Neutron-Depth-Profiling. • Both methods results agree to each other the SoC dependent Li concentrations. • Surface near reactions of LLZO redistribute, but conserve the total Li content. • Digital twin modelling based on 3D cell reconstruction shows relaxation within ∼1h. • Li concentration is ∼20 % above nominal value, reduces by high sintering temperature. [ABSTRACT FROM AUTHOR]

The differential cross sections of the first two proton groups of the 12 C ( 3 He ,p) 14 N reaction were determined within the 3 He energy range 1.34–2.86 MeV and for backward angles from 107o 107 o to 164 o with 2 o steps using two double sided silicon strip detectors. The results are presented in graphical form and they are also given as tables in the Appendix. Aiming to assist in the enrichment of the reaction database and the improvement of the differential cross section data quality, the determined cross sections were benchmarked with the measurement of thick target reaction yields from a pure glassy carbon target at two 3 He energies, 2.0 and 2.7 MeV. Furthermore, the data were accompanied by R-Matrix theory calculations, allowing for cross section data interpolation with sufficient accuracy. [ABSTRACT FROM AUTHOR]

The differential cross sections of the 9Be(3He, p i )11B reactions for i = 0–6 were determined within the laboratory energy range 1.24–2.87 MeV and for backward angles from 107 ° to 164 ° with 2 ° steps using two double sided silicon strip detectors. The obtained cross sections covered the angle and energy ranges typically used for the analysis of beryllium targets with the nuclear reaction analysis technique. The experiments were carried out at the Ruđer Bošković Institute and the determined cross sections were benchmarked with the measurement of thick target reaction yields from a pure beryllium target at two beam energies, 1.8 and 2.7 MeV. The results are presented in graphical form and for 134 ° and 164 ° are also given as tables in the Appendix. The correctness of the data, verified through the comparison of thick target spectra as well as the observed discrepancies with previous data are discussed and analyzed. [ABSTRACT FROM AUTHOR]

Prompt gamma neutron activation analysis (PGNAA) is frequently used in on–line analysis of raw materials in cement and coal industries which normally incorporates bismuth germanate (BGO) or sodium iodide (NaI(Tl)) scintillators. The quantitative results are basically undertaken through full–spectrum analysis method which requires an efficient noise reduction procedure to optimize PGNAA data. Here in this study, the empirical mode decomposition (EMD) technique has been used to reduce the noise level of PGNAA spectra of a neutron–irradiated NaCl·H 2 O solution and then the results have been compared with those of wavelet technique. The mean square errors (MSEs) comparisons confirm that both EMD and wavelet techniques can be efficiently used for noise reduction purposes, however, this study recommends the EMD technique for its independency of basic functions, simplicity and spectrum data-based operation. [ABSTRACT FROM AUTHOR]

A high-quality, large-size ZnTe ingot with the diameter of 60 mm and the length of 80 mm were prepared by the modified temperature gradient solvent method, where the Te rich solution acted as both solubility promoter and reactant. Using this method, the crystallization temperature was reduced from 1568 K to 1333 K, plus, the crystal defects could be reduced in some extent due to the lower zinc partial pressure. Few Te inclusions are found in the as-grown ZnTe crystal with the bulk factor less than 0.1%. X-ray diffraction (XRD), infrared transmission microscope, fourier transform infrared (FT-IR) spectrometer, ultraviolet–visible (UV–Vis) spectrophotometer were used to analyze the qualities and properties of the ZnTe crystals. The infrared transmittance over the wavenumber range from 500 to 4000 cm −1 is about 60% and the band gap is about 2.23 eV at the room temperature. The FWHM of the detection pulse with the THz time-domain spectroscopy (THz-TDS) is about 0.34 ps. Besides, both the radiation and detection pulse have a wide frequency distribution about 3 THz at the room temperature. These results strongly indicate that the high-quality ZnTe crystal synthesized by the temperature gradient solvent method is superior for THz device applications. [ABSTRACT FROM AUTHOR]

Particle induced gamma-ray emission (PIGE) is an ion beam technique used for isotopic elemental analysis of materials, based on gamma-ray spectroscopy. In the traditional PIGE setup, the gamma-ray detector is positioned at the neutral angles 55° or 125° with respect to the beam direction in order to measure gamma-rays with different angular distributions. Although these angles permit measurements without an a-priori knowledge of the specific angular distributions, this choice is not efficient if one wants to identify a specific element since a longer acquisition time is needed. In this work, we propose to optimize the PIGE measurements by choosing the detector angle position due to the previous knowledge of the gamma-ray multipolarity and the nuclear reaction. We present the angular distribution calculations for the isotopes most frequently identified by PIGE analysis, specially in Cultural Heritage objects. Calculations demonstrate that a gain in the intensity up to 70% can be achieved allowing the elemental identification in shorter times. This result is promising and represents a more efficient alternative to perform PIGE measurements. [ABSTRACT FROM AUTHOR]

In this paper, members of three research teams, namely the Turfan Project of the Berlin Brandenburg Academy of Sciences and Humanities, the Berlin-based research project on pigments in Central Asian paper manuscripts, and the Hamburg-based project on the history and typology of Central Asian paper manuscripts, present some of the results of their cooperation. The investigated manuscripts belong to the Berlin Turfan Collection. On the basis of different examples the contribution of scientific methods to philological scholarship within a multidisciplinary approach is demonstrated. [ABSTRACT FROM AUTHOR]

The building materials employed in Torre Gregoriana (1582–85), Terracina, have been investigated. The study focuses on the physical, chemical and mechanical characterisation of mortars, bricks and stones. The aim is to provide further insights on the knowledge of the military engineers of the time as well as to outline the material characteristics for the sake of defining compatible repair materials, details which are still missing to date. The results highlight that, due to the emergency of Turkish invasions in this period, great care was used in the building of these constructions, resulting in an accurate selection and distribution of materials by the builders (mainly hydraulic mortars and pure limestone units) and the intentional addition of reactive aggregates (such as glass particles and iron slag) for improving the durability of the structure against the aggressive marine environment. [ABSTRACT FROM AUTHOR]

One of the most fundamental processes in the Universe, nucleosynthesis of elements drives energy production in stars as well as the creation of all atoms heavier than hydrogen. To harness this process and open new ways for energy production, we must recreate some of the extreme conditions in which it occurs. We present results of experiments using a pulsed power facility to induce collective nuclear interactions producing stable nuclei of virtually every element in the periodic table. A high-power electron beam pulse striking a small metallic target is used to create the extreme dynamic environment. Material analysis studies detect an anomalously high presence of new chemical elements in the remnants of the exploded target supporting theoretical conjectures of the experiment. These results provide strong motivation to continue our research looking for additional proofs that heavy element nucleosynthesis is possible in pulsed power laboratory. [ABSTRACT FROM AUTHOR]

Abstract: A multidisciplinary approach was used to study the reason behind the deterioration of four stucco panels that decorate the vault of Room VI in the Galleria Borghese in Rome. During the last nine years the panels were subjected twice to restoration because some cracks, which appeared over the surface of the reliefs jeopardizing the integrity of the gladiators. Since the deterioration continued diagnostic investigations of the components of the stucco panels were performed to analyze both the elements and compounds, and the mineralogical structure. A microclimate study was conducted to assess the impact of the indoor environment on the panels. Measurements and statistical analysis of the data were performed in accordance with the European Standards EN 15757:2010, EN 15758:2010, and EN 16242:2012. It was concluded that the deterioration is related to high temperatures in a dry environment exacerbated by artificial lighting with incandescent lamps, located in the proximity of the panels and continuously on for 12h daily. The body heat released by numerous visitors on a daily basis is an additional problem which should not be overlooked. [Copyright &y& Elsevier]

Abstract: The paper studies the Selective Laser Sintering (SLS) of Eucalyptus/PES blend and the Investment Casting (IC) technology of the forming part. This blend is suitable for being the raw material of SLS, because not only it has low cost, but also it can be produced by SLS to form the parts with high molding precision and mechanical strength after post processing; also the prototype can be used as the investment pattern.Combining the Eucalyptus/PES blend (which is a kind of Wood Plastic Composite, WPC), SLS with IC can reduce the production cost, also shorten the product development and manufacture cycle. Meanwhile it realizes the application of low-cost WPC in precision casting production. Mould making in investment casting is an extremely important procedure, from analyzing and calculating the physical and chemical characters of the prototypes during melting. It is known that WPC parts can be burnt off by the process of low-temperature dewaxing and high-temperature roasting before investment casting. After blowing the ash off by high-pressure air, the precision of the cavity is similar to one using a wax pattern. So for single and batch production, the WPC can be used as the investment pattern of IC technology instead of wax or resin. This paper studies the investment casting technology which is suitable for patterns produced by Selective Laser Sintering of Eucalyptus/PES blend. [Copyright &y& Elsevier]

Abstract: The ruins of the Ponte di Augusto bridge, built in 27 BC close to Narni, have been investigated in recent years in order to assess the seismic resistance of the bridge. The inner structure of the existing pier was surveyed by means of four vertical core drillings, which enabled an assessment of its structural integrity, and provided material samples of its cast mortar masonry. The article presents results of tests that aim to understand the particular function of the mortars that were used. Alongside the macroscopic observations, the following instrumental methods were applied in a study of the extracted material: a macroscopic description of the mortar, thin section optical microscopy, binder SEM–EDS analysis on broken mortar samples, determining the basic physical characteristics, thermal analyses (TGA) and (DTG), and bending and compressive strength testing according to a special methodology for testing very small non-standard specimens. The measured mechanical characteristics (strength and stiffness) vary in a rather large range of values, which may indicate that the cast mortars were not set with suitable technological care. Although it cannot be stated unequivocally that the different compositions of the Ponte di Augusto pier mortars were designed intentionally to take into account changes in the load carrying capacity, from the point of view of the statics of the structure, the strongest mortar was used logically and it was probably also intentionally designed. This strongly interdisciplinary study contributes substantially to our understanding of the work of ancient Roman engineers. [Copyright &y& Elsevier]

Abstract: The use of a so-called trihedral and a T-shaped cross-flow pneumatic nebulizer with dual solution loading for inductively coupled plasma optical emission spectrometry has been studied. By these devices analyte clouds from two solutions can be mixed during the aerosol generation step. For both nebulizers the correction of matrix effects using internal standardization and standard addition calibration in an on-line way was investigated and compared to elemental determinations using a conventional cross-flow nebulizer and calibration with synthetic standard solutions without matrix matching. A significant improvement of accuracy, both for calibration with internal standardization and standard addition, was obtained in the case of four synthetic solutions containing each 40 mmol L−1 Na, K, Rb and Ba as matrix elements and 300 μg L−1 Cd, Co, Cr, Cu, Fe, Mn, Ni and Pb as analytes. Calibration by standard addition in the case of dual solution loading has been shown to be very useful in the determination of elements at minor and trace levels in steel and alumina reference materials. The results of analysis for minor concentrations of Cr, Cu and Ni in steel as well as for Ca, Fe, Ga, Li, Mg, Mn, Na, Si and Zn in alumina powder certified reference materials subsequent to sample dissolution were found to be in good agreement with the certificates. Limits of detection were found to be only slightly above those for a conventional cross-flow nebulizer and a precision better than 3% was realized with both novel nebulizers. [Copyright &y& Elsevier]

An 1800-m-deep borehole into the Nojima fault zone was drilled at Nojima-Hirabayashi, Japan, after the 1995 Hyogo-ken Nanbu (Kobe) earthquake. Three possible fracture zones were detected at depths of about 1140, 1300, and 1800 m. To assess these fracture zones in this recently active fault, we analyzed the distributions of fault rocks, minerals, and chemical elements in these zones. The central fault plane in the shallowest fracture zone was identified by foliated blue-gray gouge at a depth of 1140 m. The degree of fracturing was evidently greater in the hanging wall than in the footwall. Minerals detected in this zone were quartz, orthoclase, plagioclase, and biotite, as in the parent rock (granodiorite), and also kaolinite, smectite, laumontite, stilbite, calcite, ankerite, and siderite, which are related to hydrothermal alteration. Biotite was absent in both the hanging wall and footwall across the central fault plane, but it was absent over a greater distance from the central fault plane in the hanging wall than in the footwall. Major element compositions across this zone suggested that hydrothermal alteration minerals such as kaolinite and smectite occurred across the central fault plane for a greater distance in the hanging wall than in the footwall. Similarly, H2O+ and CO2 had higher concentrations in the hanging wall than in the footwall. This asymmetrical distribution pattern is probably due to the greater degree of wall–rock fracturing and associated alteration in the hanging wall. We attributed the characteristics of this zone to fault activity and fluid–rock interactions. We analyzed the other fracture zones along this fault in the same way. In the fracture zone at about 1300 m depth, we detected the same kinds of hydrothermal alteration minerals as in the shallower zone, but they were in fewer samples. We detected relatively little H2O+ and CO2, and little evidence for movement of the major chemical elements, indicating little past fluid–rock interaction. In the fracture zone at about 1800 m depth, H2O+ and CO2 were very enriched throughout the interval, as in the fracture zone at about 1140 m depth. However, smectite was absent and chlorite was present, indicating the occurrence of chloritization, which requires a temperature of more than 200 °C. Only smectite can form under the present conditions in these fracture zones. The chloritization probably occurred in the past when the fracture zone was deeper than it is now. These observations suggest that among the three fracture zones, that at about 1140 m depth was the most activated at the time of the 1995 Hyogo-ken Nanbu (Kobe) earthquake. [Copyright &y& Elsevier]

A large area two-dimensional position sensitive detector telescope has been designed and fabricated at NSC, New Delhi for performing ERDA based material characterization experiments. This gas ionization detector is working well with position resolution better than 2 mm and good z-separation in both high and low mass regions. Large solid angle is a pre-request to minimize the possible unwanted radiation damage during the measurement. The consequent kinematic broadening has been corrected by recording the position information. Two-dimensional position sensitivity has also been obtained. Possibility of controlled modification is shown in this work. [Copyright &y& Elsevier]

Currently, there is a need for new technology for in-line or fast at-line assessment of solid material porosity. One specific gap is a fast technology to be used in connection to roller compaction (RC) manufacturing, where the porosity of the RC ribbons is critical to the manufacturing of tablets of the right tensile strength and disintegration properties. In this paper, the development of an at-line technology for fast, non-destructive assessment of porosity of RC ribbons is reported. The technology is based on a diode laser spectroscopic technique called Gas in scattering media absorption spectroscopy (GASMAS). GASMAS measures the sample voids by laser light, giving the distance through air. The total distance the light travels is measured using time-of-flight spectroscopy (TOFS). The ratio of these measures gives an "optical porosity", which through theory relates to the porosity of the sample. We present a description of the technology, evaluations of measurement robustness and results from an experimental design where roller compactor, roll force, roll gap and formulation were varied. It is concluded that the data from two different pharmaceutical formulations is supported by the same calibration curve, which indicates that optical porosimetry is a general technique for pharmaceutical materials that does not require frequent calibrations. [ABSTRACT FROM AUTHOR]

• Pressure sensor based on two fiber Bragg gratings in a polyurethane diaphragm. • Sensors embedment at opposite directions for temperature-insensitive system. • Compensation of temperature effects in the diaphragm material and sensor sensitivity. • Pressure resolution of 1.75 Pa for constant temperature and pressure range of 0–1.2 kPa. • Temperature cross-sensitivity of 0.33 Pa/°C for a pressure range of 0–1.2 kPa. We report the development of a temperature-insensitive pressure sensor based on a pair of fiber Bragg gratings (FBGs) embedded in a polyurethane diaphragm. The pressure is transversely applied, causing a bending on the diaphragm. In such condition, the FBGs are positioned in opposite directions considering the diaphragm bending's neutral line as a reference. Thus, when the pressure is applied on the diaphragm, the wavelength shift occurs in opposite directions, i.e., one FBG has a blue shift and the other, red shift. The wavelength shift difference between both FBGs is analyzed, leading to a system with higher sensitivity when compared with the individual responses of each FBG. In addition, if the temperature sensitivities of each FBG are compensated, there is no difference in the wavelength shift (considering the difference between both FBGs) when the system is subjected only to temperature variations. However, if the system suffers simultaneous variation of temperature and pressure, there is a variation in the pressure sensitivity due to changes in the elastic modulus of the diaphragm caused by the temperature variations. For this reason, a compensation approach is proposed using the wavelength shift of each FBG as well as their difference. The sensor was tested for temperature, pressure and moisture absorption, where the maximum wavelength shift for the moisture absorption was 4 pm. For temperature and pressure responses, the sensor presented high sensitivity and linearity for all analyzed cases, leading to a pressure resolution of 1.75 Pa for constant temperature conditions. In pressure cycles under different temperatures, the compensation technique showed the feasibility of applying the proposed sensor in practical applications, where temperature variations as high as 30 °C were tested. The sensor presented a temperature cross-sensitivity of 0.33 Pa/°C. [ABSTRACT FROM AUTHOR]

In this paper, the compositions of commercial lead and non-lead X-ray protective materials were investigated by material analysis methods as FTIR-ATR, SEM/EDS, and density measurement to estimate the content of the structures, which were not declared explicitly by the manufacturers. Moreover, Monte Carlo simulations were carried out with the estimated weight ratio of the element amounts and actual densities. Hypothetical compositions were also generated and all the compositions were evaluated in terms of weight per area values versus dose transmission values. The results show that non-lead materials are basically composed of antimony and bismuth. The commercial material with the lowest density showed insufficient attenuation performance, hence it should not be proposed for lightweight apron production. The simulation results indicated also that non-lead compositions that contain adequate amount of radiopaque elements can be environmentally friendly alternatives for lightweight aprons at 60 kV and 90 kV. Besides, at higher levels as 120 kV, non-lead compositions lose their weight advantage against lead compositions. • The compositions of commercial lead and non-lead aprons were determined by material analysis methods. • The analysis showed that non-lead materials were composed of antimony and bismuth. • Monte Carlo analysis showed that adequately designated non-lead compositions can be lighter alternatives. • At higher energy levels, lead and bismuth based compositions are preferable in terms of weight. [ABSTRACT FROM AUTHOR]