Ex-situ Measurements Research Articles

Varijabilnost svojstava sadnica kitnjaka (Quercus petraea (Matt.) Liebl) sa Područja PIO "Avala"

The research of the variability within the population based on morphometric characteristics of seedlings had been conducted to preserve the available gene pool of the Sessile oak population located in the Area of Outstanding Natural Landscape (AONL) "Avala" and the controlled use of the genetic resources. Fifty best-quality trees based on the phenotypic characteristics, the carriers of the Sessile oak (Quercus petraea (Matt.) Liebl) reproductive material production were selected at the population level. Approximately 3 kg of apparently healthy and undamaged acorns were collected from each tree, separated by mother trees, and used for seedling production in the nursery under uniform environmental conditions. The root collar diameter and the height of the randomly selected 50 seedlings per half-sib line were measured at the end of the first growing season, and the sturdiness quotient was calculated based on the measured values. The obtained mean values of the morphometric characteristics indicate a high variability among the tested genotypes. This is also confirmed by the analysis of variance which determined statistically significant differences between the analyzed half-sib lines for all observed morphometric characteristics. The obtained results represent a good starting point for future research on breeding, long-term preservation, and improvement of the ecological adaptability and evolutionary potential of the Sessile oak population by applying adequate in-situ and ex-situ conservation measures. Based on the research results, it can be recommended to use this important species for reintroduction in optimal microclimatic conditions, as well as for the selection of the best individuals for reintroduction.

Forest system hydraulic conductance: partitioning tree and soil components.

Soil-leaf hydraulic conductance determines canopy-atmosphere coupling in vegetation models, but it is typically derived from ex-situ measurements of stem segments and soil samples. Using a novel approach, we derive robust in-situ estimates for whole-tree conductance (ktree ), 'functional' soil conductance (ksoil ), and 'system' conductance (ksystem , water table to canopy), at two climatically different tropical rainforest sites. Hydraulic 'functional rooting depth', determined for each tree using profiles of soil water potential (Ψsoil ) and sap flux data, enabled a robust determination of ktree and ksoil . ktree was compared across species, size classes, seasons, height above nearest drainage (HAND), two field sites, and to alternative representations of ktree ; ksoil was analysed with respect to variations in site, season and HAND. ktree was lower and changed seasonally at the site with higher vapour pressure deficit (VPD) and rainfall; ktree differed little across species but scaled with tree circumference; rsoil (1/ksoil ) ranged from 0 in the wet season to 10× less than rtree (1/ktree ) in the dry season. VPD and not rainfall may influence plot-level k; leaf water potentials and sap flux can be used to determine ktree , ksoil and ksystem ; Ψsoil profiles can provide mechanistic insights into ecosystem-level water fluxes.

Genetic diversity and structure of the narrow endemic species Crepis granatensis: implications for conservation

In this study, we studied the genetic diversity and population genetic structure of the endangered endemic Crepis granatensis, using amplified fragments length polymorphism (AFLP) and plastid DNA (cpDNA). No genetic divergences were obtained using cpDNA markers. Three primers combinations selected from a total of 12 produced a total of 421 fragments, of which 418 (99.3%) were polymorphic. The total genetic diversity of C. granatensis was moderate (Ht = 0.260). Neís gene diversity ranged from 0.202 to 0.258. The fixation index (Fst) was 0.137, suggesting low to moderate genetic differentiation among populations. The AMOVA analysis revealed that genetic diversity was mainly concentrated among individuals within populations (74%), while 8% was found among populations and 18% among regions. The Bayesian analysis and PCoA identified two genetic clusters: one corresponded to La Sagra population and the other corresponded to the Mágina populations. Based on our genetic results, it is necessary to preserve the evolutionary potential of C. granatensis by protecting all extant populations. Both in situ and ex-situ conservation measures should be considered. Reinforcement, reintroduction, and translocation programmes could be performed if necessary. Finally, such conservation strategies should be considered both in the current recovery plan and management actions for the species.

Characterizing the effects of laser control in laser powder bed fusion on near-surface pore formation via combined analysis of in-situ melt pool monitoring and X-ray computed tomography.

Near-surface or sub-surface pores are critical to the structural integrity of additively manufactured (AM) metal parts, especially in fatigue failure applications. However, their formation in laser powder bed fusion is not well-understood due to the complex processes happening near the surface, which are challenging to monitor. A lack of high-fidelity data hinders understanding of the process and its effects. It is not well-known that problems with laser control parameters such as galvanometer acceleration and laser power on/off delay can form near-surface pores in laser powder bed fusion (LPBF) AM processes, and we investigated the characteristics of these pores in this research. We also demonstrate the capabilities and processes of combined studies using in-situ melt pool images and ex-situ X-ray computed tomography (XCT) images. Using the National Institute of Standards and Technology (NIST) Additive Manufacturing Metrology Testbed (AMMT), varying laser control schemes were implemented while in-situ coaxial melt pool images were acquired during the build of Nickel superalloy parts. A combination of time-stepped digital commands, in-situ coaxial melt pool monitoring images (≈ 8 μm/pixel), and ex-situ high-resolution XCT images (≈ 3.63 μm/voxel) were demonstrated. Advanced image analysis methods were used to characterize the pores found in terms of size and shape distribution and spatial location. XCT images, in high correspondence to melt pool images, clearly show the effects of the laser control parameters. We present the complete analysis chain of AM command, in-situ melt pool imaging, ex-situ XCT acquisition, and image analysis. Possible near-surface pore formation mechanisms are explained through the comparative image analysis. The approach of compiling combined analyses based on time-stepped digital commands, in-situ monitoring results, and ex-situ XCT measurement through image analysis enables observation and categorization of the different near-surface pore formation mechanisms stemming from laser and scan control.

Operando observation of patterned nickel - gadolinium doped ceria solid oxide fuel cell anode

Nickel (Ni) - gadolinium doped ceria (GDC) is one of the promising anode materials for solid oxide fuel cells (SOFCs). However, they are not as stable as Ni - yttria-stabilized zirconia (YSZ) anodes at reducing atmosphere, since both Ni and GDC migrate and porous microstructure changes. The degradation behavior of the Ni-GDC anode is thus more complex than that of Ni-YSZ. In the present study, novel operando observations of the morphological changes of patterned Ni on a GDC substrate as well as conventional ex-situ measurements are conducted under SOFC operation. Both Ni and GDC moved dynamically in the range of several tens of microns during 51 h operation, where the three phase boundary (TPB) length dynamically changed during the operation. Nano-size GDC particles appeared on the Ni surface and the GDC surface was strongly roughened, which were the distinctive morphological changes of the patterned Ni-GDC anode.

Copulatory behavior of Knuckles pygmy lizard (Cophotis dumbara)

Nearly one in every five species of reptiles in the world is threatened with extinction and thus is conservation dependent. In order to develop effective and targeted species conservation strategies, detailed information on their distribution, systematics and ecology are necessary. Information such as the natural history and in-situ reproductive behaviors would be crucial for highly threatened species that require ex-situ conservation measures. Agamid lizards are a major component of the global reptile diversity and a significant number are threatened due to habitat loss and other threats such as smuggling.

Comparison of Target Strength of Pacific Herring (Clupea pallasii Valenciennes, 1847) from Ex-Situ Measurements and a Theoretical Model

Pacific herring (Clupea pallasii Valenciennes, 1847) is a commercially important species that inhabits the coastal waters of the North Pacific from Korea to California, USA. This study analyzed the target strength (TS; dB re 1 m2) of Pacific herring individuals (n = 14, total length (LT) = 21.3–32.3 cm) at 38 and 120 kHz using ex-situ measurements and the Kirchhoff-ray mode (KRM) model. The least-squares regressions of the TS–LT relationship for the ex-situ measurements were TS38kHz = 20 log10(LT) − 70.10 (r = 0.17) and TS120kHz = 20 log10(LT) − 70.59 (r = 0.10). The least-squares regressions for the KRM model were TS38kHz = 20 log10(LT) − 68.39 (r = 0.40) and TS120kHz = 20 log10(LT) − 69.74 (r = 0.49). The b20 value of the KRM model was 1.71 dB higher than that of the ex-situ measurement at 38 kHz but similar at 120 kHz. These results provide basic data to evaluate the distribution and abundance of Pacific herring using fisheries’ acoustic technology.

Enhanced twinning-induced plasticity effect by novel {315}α″/{332}β correlated deformation twins in a Ti-Nb alloy

This paper reports a new {315}α″ type deformation twinning system, in adition to {130}<310>α″ in a full α″ Ti-23Nb (at.%) alloy. The {315}α″ twins were identified by trace analyzes based on electron backscatter diffraction (EBSD) results, meanwhile ex-situ EBSD measurements showed that both {315}α″ and {130}α″ deformation twins transform into {332}β twins of the β parent phase after annealing at 573 K. The crystallographic correspondences between the α″ twinning systems and the {332}β twins have been analyzed theorectically, of which {315}α″/{332}β and {130}α″/{332}β correlated deformation twins were confirmed experimentally. The calculations of twinning shear, shuffle and Schmid factor were carried out to survey the priority of occurrence of these α″ twins. It is concluded that the remarkable work-hardening and enhanced plasticity arise from both {315}α″ and {130}α″ deformation twins in the present full α″ Ti-23Nb alloy.

PEFC Catalyst Layer Saturation Determination Using Representative Structure Modeling via Small Angle X-Ray Scattering

In polymer electrolyte fuel cells (PEFC), water management is one of the key aspects that governs the overall performance of a cell. Water is needed to hydrate the membrane in order to achieve good proton conductivity, while at the same time water accumulation in the catalyst and gas diffusion layer may block reactant supply to the catalytic sites. Commonly, X-ray and neutron radiography methods have been used in ex-situ and operando imaging experiments to study the water distribution and transport in the porous structures of the PEFC (1, 2). However, due to the lack of temporal and/or spatial information of these methods, as well as the risk of inducing radiation damage to the ionomer (3), the knowledge about catalyst layer saturation is limited. Here, we explore in which ways small angle X-ray scattering (SAXS) can be used as a diagnostic tool to investigate saturation on the nanometer scale particularly for PEFC catalyst layer application. So far, SAXS has been used mainly in PEFC to study Pt-nanoparticle size changes (4) and determine membrane hydration state (5). Recently, uSAXS has been employed to determine catalyst particle agglomeration in catalyst layer inks (6). An alternative technique, also in the small angle scattering family, small angle neutron scattering has been used to study water saturation in the catalyst layer in-situ (7).This study provides new insights into interpreting reciprocal space SAXS data with the help of 3D representative structure models of the catalyst layer morphology and in-silico wetting experiments. Virtual experiments for different filling mechanisms were implemented on 3D realizations of simulated Pt/C representative morphology. For each filling mechanism a specific signature can be identified in the simulated SAXS intensity profiles (see Figure 1 a-c). The simulation results of the fully wetted state were confirmed by ex-situ SAXS measurements of Pt/C catalyst layers with n-decane as model liquid (see Figure 2). Beyond the verification of the methodology, the presentation will discuss results of recent in-situ catalyst layer wetting and operando experiments. References A. Bazylak, International Journal of Hydrogen Energy, 34, 3845 (2009). P. Boillat, E. H. Lehmann, P. Trtik and M. Cochet, Curr Opin Electroche, 5, 3 (2017). J. Roth, J. Eller and F. N. Buchi, J Electrochem Soc, 159, F449 (2012). M. Povia, J. Herranz, T. Binninger, M. Nachtegaal, A. Diaz, J. Kohlbrecher, D. F. Abbott, B. J. Kim and T. J. Schmidt, ACS Catal, 8, 7000 (2018). N. Martinez, G. Gebel, N. Blanc, N. Boudet, J. S. Micha, S. Lyonnard and A. Morin, ACS Appl Energ Mater, 2, 3071 (2019). M. Wang, J. H. Park, S. Kabir, K. C. Neyerlin, N. N. Kariuki, H. F. Lv, V. R. Stamenkovic, D. J. Myers, M. Ulsh and S. A. Mauger, ACS Appl Energ Mater, 2, 6417 (2019). J. Lee, S. Escribano, F. Micoud, G. Gebel, S. Lyonnard, L. Porcar, N. Martinez and A. Morin, ACS Appl Energ Mater, 3, 8393 (2020). Figure 1

Initial Approaches for Developing Low-Cost Materials for PEM Water Electrolyzer Porous Transport Layers

Capital cost is a major barrier to the widespread commercialization of water electrolysis technology. Metal-based stack components, particularly the porous transport layers (PTLs) and bipolar plates (BPPs), are estimated to represent 30-70% of electrolyzer stack cost [1]. Current commercial approaches utilize titanium, which forms a passive oxide film that provides corrosion resistance in the electrolyzer anode environment. During operation, however, the electrically resistive surface oxide film grows, which leads to significant increases in cell and stack series resistance losses. Successful mitigation strategies so far have relied on a platinum-group metal (PGM) coating. With titanium alloy base materials and PGM coatings being relatively expensive, there is significant potential to reduce electrolyzer stack cost by using alternative materials.In the more advanced trajectory of fuel cell research and development, there has been considerable exploration and validation of a variety of base materials and surface modifications [2]. The primary materials have been metals or carbon-based (e.g. graphite bipolar plates or carbon paper diffusion media). Although potentially suitable in the electrolyzer cathode environment, carbon is not stable under the highly oxidizing and acidic environment of an electrolyzer anode. Therefore, metal alloys that form passive oxides are necessary, but such passive oxides generally have high electrical resistance. This defines the primary design challenge for engineering new PTL materials.In efforts toward selecting, screening, and developing promising, low-cost PTL materials, we have explored and developed ex-situ characterization techniques to be used in concert with in-situ PTL performance validation. Ex-situ measurements include interfacial contact resistance, electrochemical corrosion current, permeability, and insulating oxide formation. One facet of ex-situ corrosion testing methodology involves individually varying stressors such as temperature, pH, and potential to quantify the influence of each. Another facet employs time-lapse microscopy to observe and interpret distinct corrosion modes. These approaches will be discussed and example results for baseline and low-cost PTL materials and surface modifications will be presented.

Chemically coupled 0D-3D hetero-structure of Co9S8-Ni3S4 hollow spheres for Zn-based supercapacitors

As one of the most promising supercapacitor electrode materials, transition metal sulfides (TMSs) with unique hollow structural features and multiple functional compositions have attracted tremendous interest in the scientific community. Herein, by rationally design a Ni-LDH@Co-BTC yolk-shelled-structure as a template, we successfully fabricate a chemically coupled 0D-3D hetero-structure of Co9S8-Ni3S4 hollow spheres (Co9S8-Ni3S4 HS). During the sulfidation process, the free Co2+ ions derived from the hydrolysis Co-BTC core are anchored by S-rich hierarchical Ni3S4 hollow microsphere shell and further reacted with emerging S2− ion from the hydrolysis of TAA to form the chemically coupled Co9S8 and Ni3S4. The optimized Co9S8-Ni3S4 HS-13 shows prominent supercapacitor performance (239.30 mAh g−1 (1723 F g−1) at 1 A g−1) and excellent cycling stability (94.7 % capacitance retention after 3000 cycles). The as-fabricated Co9S8-Ni3S4 HS-13//rGO-Zn hybrid Zn-based supercapacitor presented a high energy density of 381.63 Wh kg−1 at 1.67 kW kg−1 and excellent cycling durability (91.7 % capacitance retention after 5000 cycles). Then, through the ex-situ XPS measurements, the energy storage mechanism of the Co9S8-Ni3S4 HS-13//rGO-Zn device is proved to be a novel double ions (OH− and Zn(Ⅱ)) intercalation/deintercalation reaction.

Measurement Technique of Oxygen Concentration in Narrow Channels of PEFCs Based on Transmission Laser Absorption Spectroscopy

The oxygen transport on the cathode side of polymer electrolyte fuel cells (PEFCs) is an important factor that determines their performance. This study presents a fiber-optic gas sensing technique for monitoring the oxygen concentration in flow channels of operating PEFCs based on transmission tunable diode absorption spectroscopy (TDLAS). As the first stage, the fiber-optic transmission TDLAS system was developed and applied to the ex-situ measurement of oxygen concentration in the narrow channels of a simulated flow cell. It was found that the second-harmonic (2f) absorption spectra of oxygen can be clearly detected without optical noises even though the channel width is narrowed to 1.0 mm. The calibration results obtained from the TDLAS measurements enable to accurately estimate the oxygen mole fraction within the flow cell. The fiber-optic transmission TDLAS is applicable for the oxygen monitoring in submillimeter-scale channels of actual PEFCs.

Comprehensive investigation of the corrosion state and surface properties of the stainless steel tubes of steam generators

Evaluating the water chemistry in the primary circuit and the effect of chemical econtamination&#x0D; of the heat exchanger tubes performed by the AP-CITROX (AP: alkaline permanganate; CITROX: citric and oxalic acid) procedure at Paks NPP (Hungary), a project dealing with the comprehensive investigation of the general corrosion state of the steam generators (SGs) has been initiated. Owing to the fact that there is no investigation method available for the in-situ monitoring of the inner surfaces of heat exchanger tubes, a research program based on sampling as well as on ex-situ electrochemical (voltammetric) and surface analytical measurements (SEM-EDX, CEMS, XRD, XPS) was developed and elaborated. In the time period of 2000-2008 - within the frame of the above project - 45 stainless steel specimens, cut out from various locations of the steam generators of the Paks NPP were investigated. Based on the measured corrosion characteristics (corrosion rate, thickness and chemical composition of the protective oxide-layer) it was found that these parameters are strongly dependent on the decontamination history of steam generators. The present work gives a brief overview on the general corrosion state of the heat exchanger tubes of SGs, concerning the long-term effects of the AP-CITROX procedure on the chemical composition and structure of the protective oxide-layer.

A Systematic Study of Electrolyte Additives in Single Crystal and Bimodal LiNi0.8Mn0.1 Co0.1O2/Graphite Pouch Cells

A few weight percent of electrolyte additives can dramatically improve Li-ion battery performance and lifetime. A systematic investigation of a series of electrolyte additive formulations was performed on bimodal (BM) and single crystal (SC) LiNi0.8Mn0.1Co0.1O2 (NMC811)/artificial graphite (AG) pouch cells. Long-term cycling tests at different temperatures (20 °C, 40 °C, and 55 °C) and different upper cutoff voltages (4.06 V and 4.20 V) were performed. These tests results were combined with advanced characterization techniques like ultra-high precision charging (UHPC), ex-situ gas measurement, and automatic cell storage tests to rank the additives based on their effectiveness. Radar plots and a figure-of-merit (FOM) approach were further utilized to summarize results for the BM and SC NMC811/AG cells. This work provides a useful benchmark for those developing NMC811/graphite cells and gives important insights for future electrolyte additive studies.

Vision-based in-situ monitoring system for melt-pool detection in laser powder bed fusion process

A low-cost, lateral off-axis non-IR imaging system is proposed to inspect the melt-pool in the Laser Powder Bed Fusion (L-PBF) processing of IN718 powder and stainless steel 316 L powder. In the proposed system, a perspective transformation method is applied to transform the captured side-view image into a top-view image and the melt-pool boundary is then determined based on an inspection of the gray-level intensity profile of the captured image and its first derivative. For the IN718 L-PBF process, the measurement results obtained for the melt-pool width and melt-pool length vary by no more than 13% and 3%, respectively, from the experimental results reported in the literature. For the SS316L, the measured melt-pool width is within 6% of the ex-situ measurements obtained by optical microscopy, while the melt-pool length differs by no more than 9% from the numerical predictions. Overall, the results show that the proposed system provides a viable means of detecting potential build failures during the L-PBF process and improving the yield of the fabrication process as a result.

Hierarchically structured Ti3C2T MXene paper for Li-S batteries with high volumetric capacity

Due to the low density of sulfur and the large portion of carbon-based materials used as conducting network and lithium polysulfide (LiPS) host, the practical volumetric energy density of lithium–sulfur (Li–S) batteries barely rivals the Li-ion batteries. Here, MXene (Ti 3 C 2 T x )-based membrane with unique 3D hierarchical structure, high electronic conductivity, abundent active binding sites, fast ion transport, and high affinity for lithium polysulfides has been developed as a new host material to improve the electrochemical performance of Li-S batteries. With a density of 2.2 g cm −3 , a MXene-based cathode containing 4.0 mg cm −2 sulfur delivers a high volumetric capacity of 2.7 Ah cm −3 after 200 cycles. Based on operando XRD and ex-situ XPS results, we find that the Ti-OH bonds present on the surface of MXene membrane can effectively trigger the LiPS transformation. Furthermore, α -S 8 , as the stable charge product, is first reported in MXene-based host along with its possible important role in curtailing active mass loss and enhancing cycling capability. Our results reveal that 2D MXene with rationally-designed architecture enable high volumetric capacity Li-S batteries for practical applications. An excellent lithium-sulfur battery with high volumetric capacity is enabled by a 3D hierarchical MXene (Ti 3 C 2 T x ) electrode, which can effectively regulate the polysulfides shuttling via a dual-play immobilization mechanism of thiosulphate/polythionate redox conversion and Lewis acid-base interactions. α -S 8 is first reported as the stable charge product and its important role is studied in detail. • An efficient encapsulation strategy was developed to construct a robust hierarchically structured MXene cathode of Li-S batteries. • Combined in-situ and ex-situ measurements suggest that the thiosulphate/polythionate complex serves as key redox transfer mediator to facilitate the surface-redox reaction. • α-S 8 is firstly reported as the stable charge-stage product and its fast nucleation and stability effectively curtail active mass loss and enhances cycling capability.

In-situ thermal transport measurement of flowing fluid using modulated photothermal radiometry

In situ thermal transport measurement of flowing fluid could be useful for the characterization and diagnosis of practical thermal systems such as fluid heat exchangers and thermal energy storage systems. Despite abundant reports on the ex-situ thermal conductivity measurement of stagnant fluids, a suitable technique for the thermal conductivity measurement of flowing fluid has been rarely reported. This paper presents the thermal conductivity measurement of flowing fluid within a pipe using a non-contact modulated photothermal radiometry (MPR) technique, where the surface of the pipe is heated by an intensity-modulated laser and the heat diffuses into the fluid with suitable modulation frequency. We design a tube section with small wall thickness suitable for the MPR measurements to maximize the sensitivity of the thermal response to the fluid properties while minimizing the lateral heat spreading effect. Intrinsic thermal conductivity of different fluids was obtained within a proper range of frequency and flow velocity where the forced convection effect is negligible. The forced convection effect became prominent at high flowing velocity and at low modulation frequency, leading to higher effective thermal conductivity of the fluid. It is found that the intrinsic thermal conductivity could be obtained when the flow velocity is less than 100 mm/sec and ReD1/2Pr1/3 < 100 for DI water and Xceltherm oil under the specified experimental conditions, where ReD is the Reynolds number and Pr is the Prandtl number.

Galvanodynamic Electrochemical Impedance Spectroscopy on a Solid Oxide Cell Stack for In-Operando Diagnostics

Introduction Lifetime expectations and uncertainties regarding end-of-life performance hinder widespread deployment of fuel cell technology. Conventional cell performance diagnostic methodologies rely upon either ex-situ measurements, which lack an immediate connection with the physical degradation phenomena, or upon single cell in-operando electrochemical impedance spectroscopy (EIS), which often is troubled by challenges of feature identification of the spectra and uncomplete representation of the full stack operating conditions in large scale systems [1]. To address these problems, we propose to use electrochemical impedance spectroscopy techniques as diagnostic and prognostic tools to predict the cause-effect relationship between degradation phenomena and stack operating conditions. This experimental methodology can be potentially integrated into commercial systems for stack state of health monitoring during continuous operation. Experimental methods Through experimental study on a solid oxide fuel cell (SOFC) short stack, we explore the potential use of electrochemical impedance spectroscopy (EIS) for in-operando diagnosis. We identify the mechanisms contributing to this system EIS, by carrying out pristine cell/stack tests at different operating conditions (gas partial pressure, current, temperature).We collect experimental data on a 6-cell short-stack with active area of 80 cm2 per cell. Each anode-supported cell features a Ni-YSZ fuel electrode (240 μm), a Sr-doped LaMnO3 (LSM) oxygen electrode (40 μm) and an 8 mol% Y2O3 stabilized Zirconia (YSZ) electrolyte (8 μm). In our experimental setup, the first (reference electrode, i.e., cathode of cell no.1) and last (i.e., anode of cell no.6) electrodes are connected to the counter and working electrode leads of the potentiostat, respectively. This allows connecting the diagnostic system in parallel with the load and the stack, while performing floating ground galvanodynamic EIS measurements. This configuration enables the load to impose the operating current of the stack, while the potentiostat modulates the signal without any current in its main circuit. Reference and working sensing connections to individual cells in the stack are independent on the potentiostat leads.We operate the stack with mixtures of hydrogen, nitrogen and steam at the fuel electrode and mixtures of oxygen and nitrogen/helium at the oxygen electrode. We control the operating temperature via an electric furnace, while monitoring the stack temperatures with a set of six thermocouples, as reported in [2]. Discussion Figure 1 compares the measured EIS spectra for each cell in the short stack at beginning of life and after a major degrading event. With continuous stack monitoring, we are able to identify how degradation phenomena differently impact the state of health of the cells during the stack normal operation. This allows identifying the most degrading operating conditions of the system in real-time, hence informing the operational planning and lifetime maximization strategies of the system. Conclusions Preliminary results suggest that our methodology can provide meaningful insights regarding the cause and nature of the physical processes at the origin of degradation phenomena in solid oxide cells. This process is particularly interesting as a non-disruptive diagnostic and prognostic tool for commercial scale systems that need to optimize their operating conditions to either maximize their lifetime or meet a performance target at end-of-life.Figure 1 – (left) Beginning of life and (right) degraded cell plot comparison of experimental EIS for a 6-cell short stack at 1 A. Tstack=750°C, Anode flow=1.2 Nl min-1 (N2/H2=50/50%), Cathode flow=18.9 Nl min-1 (Air)[1] A. Baldinelli, L. Barelli, G. Bidini, A. Di Cicco, R. Gunnella, M. Minicucci, A. Trapananti, 2019, p. 020012.[2] L. Mastropasqua, S. Campanari, J. Brouwer, J. Power Sources 2017, 371, 225–237. Figure 1

POLLUTION INDEX AND ECONOMIC VALUE OF VANNAMEI SHRIMP (Litopenaeus vannamei) FARMING IN INDONESIA

Shrimp farming has contributed a large share in Indonesia’s aquaculture portfolio for at least a decade, and a national plan to increase shrimp production by 250% has been recently laid out. However, boosting shrimp productions could lead to unintended consequences in environmental and socio-economic negative impacts. The rapid development of vannamei farming in Java has increased coastline land clearings and demands of fertilizers, feeds, and chemicals to sustain the farming activities. Such pressures will eventually lead to a reduced environmental capacity and the farming efficiency itself. This study aimed to study the environmental impacts and business performance of intensive shrimp farming in Indonesia. The study was conducted in Aquaculture Business Center (ABC) in Karawang for four months, from July to October 2020. In-situ and ex-situ measurements of water quality parameters were done at six sampling stations directly post-harvest water discharge. The measured parameters consisted of temperature, pH, dissolved oxygen, ammonia (NH3), nitrite (NO2), nitrate (NO3), phosphate (PO4), alkalinity, and salinity. Pollution Index (PI) was used as the primary method to determine the environmental impacts of the shrimp farming. The R/C Ratio was used to analyze the business performance of the company. The results showed that the water quality index in the ABC area was categorized as lightly polluted in station 1 (PIj 4.52) and station 5 (PIj 4.37), moderately polluted in station 2 (PIj 6.24), station 3 (PIj 6.72), and station 4 (PIj 6.13) and heavily polluted in station 6 (PIj 111.06). The determined R/C ratio was 1.10, meaning that the shrimp farming is classified as economically profitable. Although the shrimp farming’s economic performance value is very good, the water conditions affected by waste from the shrimp pond culture will reduce the R/C ratio in the future if not properly managed.

Systematic Characterization of Degraded Anion Exchange Membranes Retrieved from Vanadium Redox Flow Battery Field Tests.

Commercially available anion exchange membranes were retrieved from VRFB field tests and their degradation due to the various operation conditions is analyzed by in-situ and ex-situ measurements. Ion exchange capacity, permeability and swelling power are used as direct criteria for irreversible changes. Small-angle X-ray scattering (SAXS) and Differential scanning calorimetry (DSC) analyses are used as fingerprint methods and provide information about the morphology and change of the structural properties. A decrease in crystallinity can be detected due to membrane degradation, and, in addition, an indication of reduced polymer chain length is found. While the proton diffusion either increase or decline significantly, the ion exchange capacity and swelling power both are reduced. The observed extent of changes was in good agreement with in-situ measurements in a test cell, where the coulombic and voltage efficiencies are reduced compared to a pristine reference material due to the degradation process.