Geometric Surface Area Research Articles

Enhanced low-temperature H2-selective catalytic reduction performance and selectivity of Pt/ZSM-5–TiO2 washcoated monolithic catalysts for NOx reduction

Hydrogen-selective catalytic reduction (H2-SCR) is a promising technology for reducing nitrogen oxide (NOx) emissions at low temperatures, but the selectivity of this process is limited by the generation of N2O. To achieve enhanced denitrification (deNOx) performance, H2-SCR catalysts with mixed zeolite and TiO2 supports washcoated on monolithic cordierite were developed. The catalyst support, active metal type and content, and monolithic cordierite cell density significantly influenced the H2-SCR performance. The xPt/TiO2 catalysts (where x is the metal content, wt.%) achieved >90% NOx conversion 135–180 °C, whereas the xPd/TiO2 catalysts exhibited poor H2-SCR activity, with <30% NOx conversion. In contrast to 0.5Pt/TiO2, the 0.5Pt/zeolite catalysts achieved high NOx conversion at 140–150 °C (91% at 140 °C for 0.5Pt/ZSM-5 > 89% at 140 °C for 0.5Pt/BETA >85% at 150 °C for 0.5Pt/SSZ-13), suggesting that zeolite supports significantly promote H2-SCR activity at low reaction temperatures. For the 0.5Pt/ZSM-5 washcoated monolithic catalyst, increasing the cell density from 400 to 900 cpsi significantly improved the NOx conversion from 52% to 90% at 100 °C owing to the increased geometric surface area and open frontal area of monolithic cordierite. For catalyst with mixed supports (0.5Pt/yZSM-5zTiO2) changing the ZSM-5/TiO2 ratio (y:z) from 25:75 to 90:10 increased the low-temperature NOx conversion from 39% to 89% at 100 °C, indicating that the deNOx characteristics can be tuned. With NO as the reactant, the 0.5Pt/90Z10T catalyst produced the lowest N2O share (8–17%) within the temperature window of maximum NOx conversion, resulting in an increased N2 share (83–88%). Thus, the synergetic effect of mixed ZSM-5/TiO2 catalyst supports can enhance low-temperature NOx conversion and mitigate N2O formation.

Dielectric Roasting Induced Physical, Mechanical, and Grinding Characteristics of Black Pepper (Piper nigrum)

The present study was focused on microwave (dielectric) roasting (300-600 W, 5-15 min) on the physical, textural, color, and grinding of black pepper. The microwave roasting is a volumetric heating that causes rapid removal of moisture, and internal pressure generated inside the seed tends to change the physiology and physical attributes. An increase in roasting power and time increased the geometric mean diameter (5.216 to 6.283 mm), sphericity (0.883 to 0.927), aspect ratio (0.853 to 0.914), and surface area (85.560 to 124.262 mm2) of black pepper. Whereas the significant ( p &lt; 0.05 ) reduction was observed in 100 grain weight (7.55 to 5.63 g), bulk density (500.97 to 251.38 kg/m3), fracturability (72.99 to 1.78 N), and hardness (63.65 to 1.61 N). Roasting led to browning, and a significant reduction was observed in the color parameters, L ∗ (22.82 to 17.76), a ∗ (2.47 to 0.56), and b ∗ (2.41 to -0.75) with a significant ( p &lt; 0.05 ) increase in total color difference (0.96 to 5.30). Roasting also increased the particle size distribution in grounded power, and the mean particle size increased from 121.72 to 146.14 μm.

A new approach to model the fluid dynamics in sandwich packings

Abstract Sandwich packings represent new separation column internals, with a potential to intensify mass transfer. They comprise two conventional structured packings with different specific geometrical surface areas. In this work, the complex fluid dynamics in sandwich packings is modeled using a novel approach based on a one-dimensional, steady momentum balance of the liquid and gas phases. The interactions between the three present phases (gas, liquid, and solid) are considered by closures incorporated into the momentum balance. The formulation of these closures is derived from two fluid-dynamic analogies for the film and froth flow patterns. The adjustable parameters in the closures are regressed for the film flow using dry pressure drop measurements and liquid hold-up data in trickle flow conditions. For the froth flow, the tuning parameters are fitted to overall pressure drop measurements and local liquid hold-up data acquired from ultra-fast X-ray tomography (UFXCT). The model predicts liquid hold-up and pressure drop data with an average relative deviation of 16.4 % and 19 %, respectively. Compared to previous fluid dynamic models for sandwich packings, the number of adjustable parameters could be reduced while maintaining comparable accuracy.

Moisture dependent postharvest physical and textural characteristics of brown sesame seed (var. TMV-4)

Physical and textural characteristics are important in design and manufacturing of harvest and post harvest machines. Some postharvest physical and textural characteristics of brown sesame seed (var. TMV-4) were determined as a function of moisture content in the range of 4.3 per cent to 20 per cent (d.b). The axial dimensions, geometric mean diameter, surface area, volume, sphericity and aspect ratio were found to be increasing linearly for all studied moisture levels. Furthermore, the thousand seed mass, true density, porosity and the angle of repose also increased linearly whereas, bulk density decreased linearly with the increase of moisture content under study. The results showed that the static coefficient of friction on four different surfaces of plywood, mild steel, galvanized iron and glass also increased linearly for all level of moisture. The initial cracking force, average rupture force and average rupture energy decreased linearly with increased moisture content of 4.3 to 20 per cent (d.b.).

Effect of Short-Term Storage Temperature on Mechanical Properties of ‘Istanbul’ Medlar

The study investigated the effect of short-term storage time on the mechanical (rupture force, rupture energy, deformation) properties of the ‘Istanbul’ medlar cultivar grafted on Quince A (QA) and Quince Province BA29 (BA29) quince clone rootstock. The study gives the average values of the physical properties (weight, size, geometric mean diameter, sphericity, surface area, true density, bulk density, and porosity) of the ‘Istanbul’ medlar cultivar. The changes in breaking force, breaking energy, and deformation values of 'Istanbul' medlar varieties stored at room temperature (251 °C) and cold storage (41 °C) for 5 days were investigated. Separate measurements were made for skin and skinless fruits. The average rupture force value of fruits of the ‘Istanbul’ medlar cultivar stored at 25 °C was determined as 8.82 N, deformation 4.66 mm, and rupture energy 0.035 J. The average rupture force value of the fruits of the ‘Istanbul’ medlar cultivar stored at 4 °C was determined as 10.06 N, deformation 5.16 mm, and rupture energy 0.043 J. It was found that the storage conditions had a statistically significant effect on the rupture force, rupture energy, and deformation values of the QA and BA29 rootstocks of the ‘Istanbul’ medlar cultivar (P≤0.001).

Electrochemical CO2 Reduction Using a Free-Standing Porous Cu Framework as Catalyst

Due to fossil fuel combustion, the CO2 concentration in the atmosphere has reached around 410 ppm, causing major climate change on our planet. It thus becomes increasingly important to limit CO2 emissions or even remove CO2 from our atmosphere. One promising pathway to transform CO2 into useful chemicals is electrochemical reduction. However, electrochemical CO2 reduction is a challenging process that requires robust, low cost and stable catalysts. Copper is a promising candidate, at which CO2 can be reduced to several types of hydrocarbons.In this contribution, CO2 reduction was performed with a free-standing porous copper catalyst that was prepared using an inexpensive hydrogen assisted electroplating process [1]. The porous copper framework has good mechanical stability and a large internal surface area. Furthermore, it can easily be manufactured on a large scale. Due to its porous nature with tunable pore sizes this copper framework is at the same time gas diffusion layer and catalyst. A porous sample with a 10 cm2 geometric surface area was assembled in a custom-made electrochemical cell consisting of an open cell anode compartment, a closed compact cell for the cathode, separated by a cation-exchange membrane. CO2 mixed with water vapor is transported to the free-standing porous Cu in the closed compact cell for the CO2 reduction process. The electrochemical cell is connected to a gas chromatograph (GC) for further gas phase product analysis. The experiments were performed in the potential range between -0.3 V vs RHE and -1.7 V vs RHE in 0.5 M KHCO3 as the anolyte. GC measurements show a considerable amount of methane (CH4), ethylene (C2H4), ethane (C2H6), and propane (C3H8) which indicates a successful reduction reaction of the CO2 on the porous copper framework surface.[1] M. Kurniawan, M. Stich, M. Marimon, M. Camargo, R. Peipmann, T. Hannappel, A. Bund: "Electrodeposition of cuprous oxide on a porous copper framework for an improved photoelectrochemical performance." J. Mater Sci. 56 (2021) 11866-11880

Oxygen Evolution Activity on Mo Added Zr Oxide Catalyst in Alkaline Solution

On Sep. 26, 2022, Hydrogen energy ministerial meeting (H2 EM 2022) was held by the ministry of economy, trade and industry (METI) of Japanese government as online special event with cabinet members and officials from 30 countries, regions, and organizations. In the chair’s summary of meeting, an additional goal also proposed the amount of renewable and low-carbon hydrogen to be produced by 2030 of at least 90Mt H2. In the open session, the water electrolysis was one of the main topics of the session, and due to the demand for “Green Hydrogen” as already described in chairman’s summary, installed capacity of water electrolyzer has been required for the huge size of its module [1]. Here, “Green Hydrogen” is the hydrogen which is produced by the electricity from renewable energies introducing in our previous study [2].Alkaline water electrolysis (AWE) has already commercialized and recently applied its system for the Power-to-Gas (PtG) all over the world. In the Fukushima hydrogen energy research field (FH2R) in Japan, one of the largest module of AWE named “Aqualyzer” has operated from 2020. However, previous literature reported that the degradation of Ni anode occurs operating by variable renewable energy (VNE) [3]. From this point of view, the alternative anode with high durability against VNE should be required for green hydrogen production. We focused on zirconium oxide-based electrocatalyst (ZrOx) and have studied the catalytic activity of its thin film fabricated by sputtering procedure for oxygen evolution reaction (OER) [4-5]. In this study, we have investigated the OER activity of Mo added ZrO2 (Mo-ZrO2) fabricated by atomic layer deposition (ALD) and arc plasma deposition (APD) in alkaline solution.Mo-ZrOx was formed on Ti rods as a base material, using by ALD and APD. In the step of ALD, Tetrakis(dimethylamino)zirconium (TDMAZr) and water were used as precursor and oxidant of ZrO2, and the substrate was heated at 225 oC. The thickness of ZrO2 film was 10 nm for preparation. Then, the MoOx was fabricated by APD using Mo metal as target material at 0.74 Pa of partial pressure of oxygen and the substrate was heated at 300oC. At last, the annealing was performed under Ar atmosphere at 300 oC to produce the Mo-ZrO2 catalyst. In the case of inserting interlayer, TaOx was formed by the R.F. magnetron sputtering before ALD step. All electrochemical measurements were carried out using a three-electrode cell at 30 oC in 7 M KOH. A reversible hydrogen electrode (RHE) and a carbon plate were used as a reference and a counter electrode, respectively. Mo-ZrO2 catalyst on Ti rod was used as working electrode. In order to evaluate the catalytic activity for the OER, slow scan voltammetry (SSV) was performed under N2 atmosphere. The current density (i geo) was based on the geometric surface area of the working electrode. The resistance of the film (R film) and charge transfer (R ct) was evaluated by AC impedance spectroscopic measurements in the frequency range from 105 to 10−1 Hz.Figure 1 shows Tafel plots of OER on Mo-ZrO2 catalysts with and without interlayer of TaOx (Mo-ZrO2/TaOx or Mo-ZrO2). Compared with previous result, Tafel plot of OER on Mo-ZrOx fabricated by sputtering (Mo-ZrOx_SP) was also showed in Fig. 1. The i geo at 1.8 V vs RHE on the Mo-ZrO2/TaOx was larger than that on the Mo-ZrO2, and was also similar to that on the Mo-ZrOx_SP. The Tafel slope of Mo-ZrO2/TaOx was 95 mV dec-1, and it was the smallest compared to other catalysts such as Mo-ZrO2 and Mo-ZrOx_SP. From the results of electrochemical impedance spectroscopy (EIS), the R film and R ct of Mo-ZrO2 was obviously larger than that of Mo-ZrO2/TaOx and Mo-ZrOx_SP. According to XPS result, ZrO2 around surface of both Mo-ZrO2/TaOx and Mo-ZrO2 were still remained after electrochemical measurement. Above all, the insert of interlayer of TaOx between Mo-ZrO2 and Ti rod (Mo-ZrO2/TaOx) was effective for activity and stability for OER, and it also has similar OER activity to Mo-ZrOx_SP.Acknowledgement: This work is partially supported by Hitachi Metals-Materials Science Foundation, Yashima Environment Technology Foundation, and Amano Institute of Technology.Reference https://hem-2022.nedo.go.jp/archive/ Ota, A. Ishihara, K. Matsuzawa, and S. Mitsushima, Electrochemistry, 78, 970 (2010). Ichikawa, K. Matsuzawa, Y. Kohno, I. Nagashima, Y. Sunada, Y. Nishiki, A. Manabe, and S. Mitsushima, ECS Trans., 58(33), 9 (2014). Matsuzawa, A. Ishihara, A. Ohshi, S. Mitsushima, and K. Ota, Mater. Sci. Eng. B, 267, 115112 (2020).K. Matsuzawa, A. Nozaka, and A. Ishihara, Abst. 241st ECS Meeting, #I02-1347 (2021). Figure 1

Development of Hybrid Electrodes Based on a Ti/TiO2 Mesoporous/Reduced Graphene Oxide Structure for Enhanced Electrochemical Applications

Titanium/TiO2 mesoporous/reduced graphene oxide structure for construction of a hybrid electrode was successfully developed using a facile and effective spin-coating technique. The as-prepared structures were characterized using ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, RAMAN analysis, scanning electron microscopy (SEM) coupled with elemental analysis (EDX), and atomic force microscopy (AFM). In addition, the electrochemical behavior was assessed by cyclic voltammetry (CV) in a 1M KNO3 supporting electrolyte and in the presence of 4 mM K3Fe(CN)6 to determine the electroactive surface area and apparent diffusion coefficient of the hybrid electrode. The charge transfer resistance was investigated via electrochemical impedance spectroscopy (EIS) in a 0.1 M Na2SO4 supporting electrolyte to confirm the role of reduced graphene oxide on the electrode’s surface. The potential application of as-obtained hybrid electrodes in electroanalysis was tested through cyclic voltammetry in the presence of doxorubicin as the target analyte, in the concentration range between 1 to 7 mg L−1 DOX. By using mesoporous TiO2 with a high specific surface area (~140 m2 g−1) in the synthesis of the composite material based on a Ti/TiO2(Ms)/rGO hybrid structure, was obtained a 2.3-times increase in electroactive surface area than the geometrical surface area of the hybrid electrode. These results provide new insights into the development of high-performance and cost-effective electrochemical sensors based on reduced graphene oxide films on metallic structures for applications in the detection processes of drugs from wastewater.

Investigating mass transfer coefficients in lean methane combustion reaction through the morphological and geometric analysis of structured open cell foam catalysts

In this work, we characterized ceramic open cell foams made of zirconia, silicon carbide and alumina of different nominal pore densities (30–45 ppi) using X-ray computed microtomography. This technique allowed the comprehensive and quantitative extraction of morphological and geometrical characteristics of the structures (pore size, strut diameter and length, node diameter, open porosity and specific geometrical surface area). An empirical model was proposed to determine the specific surface area from parameters easily accessible with standard laboratory equipment. Moreover, lean CH4 combustion tests were performed on ceramic foams coated with PdO/Co3O4 at 3 wt%. Mass transfer coefficients of the foams were measured by monitoring the oxidation reaction under diffusional control conditions. We derived a dimensionless correlation of the type Sh = A∙Rem∙Sc1/3. Finally, the pressure drop across the foams as a function of surface velocity was evaluated and compared with various experimental data and models available in the literature.

Catalytic Activity and Stability of Non-Platinum Group Metal Oxides for the Oxygen Evolution Reaction in Anion Exchange Membrane Electrolyzers

The activities and stabilities of non-platinum group metals (PGMs) in the forms of monometallic (Mn2O3, Fe2O3, Co3O4, NiO) and bimetallic (NiFe2O4, CoNiO2) oxides were assessed for the oxygen evolution reaction (OER) in alkaline media and compared with IrO2. Both half-cell, rotating disc electrode (RDE) apparatus and single-cell, membrane electrode assemblies (MEA) were used to study kinetic and device-level performance in parallel and to provide insights into the use of these materials in anion exchange membrane (AEM) electrolyzers. Normalization of RDE results by geometric and physical surface areas, double layer capacitance, and metal content probed differences in physically vs electrochemically accessible surface areas and ensured reported trends were independent of the normalization method. The results showed that: (i) Ni- and Co- containing materials met or exceeded IrO2 performance in both RDE and MEA testing, (ii) Co3O4 deactivated over time-on-stream (1.8 V for 13.5 h) due to oxide and, relatedly, particle growth, (iii) NiFe2O4 increased in activity over time-on-stream due to dissolution of Fe and an increased Ni/Fe ratio, and (iv) reduction of catalyst layer resistance is an avenue to further increase device-level performance. These results demonstrated the clear viability for non-PGMs to be used as anode catalysts in AEM devices.

ID: 219864 Hierarchical Surface Restructuring for Next Generation Neural Interfacing Applications

Selective and targeted stimulation of small populations of neurons in close proximity to implantable electrodes is an essential prerequisite for their success. Additionally, the trajectory for further refinement of neural interfacing devices is in large part predicated on increased miniaturization of electrodes that enables higher spatial resolution, precision, and reliability. To achieve miniaturization, the geometric surface area of the electrodes must be reduced while the electrochemical surface area is increased. Therefore, availability of highly electroactive electrode materials or surfaces capable of improving the electrodes’ electrochemical performance is paramount as it ensures delivery of enough charge across the electrode/tissue interface for stimulation as well as low impedance at the interface for sensing and recording purposes. In the past two decades, several surface treatment technologies e.g., coatings, thin films, nanomaterials, physical and electrochemical techniques have been vastly investigated. Despite varying degrees of improvement in electrochemical performance, most of these techniques are still facing several challenges and shortcomings, e.g., poor performance and durability, manufacturing, scalability, and commercialization challenges. In this research, a proprietary, innovative, tunable, scalable, and commercially viable electrode surface treatment technology (hierarchical surface restructuring) is introduced.

Charge Injection Enhancement Comparisons of Iridium Oxide Microelectrodes In Vitro and In Vivo Using a Portable Neurostimulator.

Microelectrodes are desired to deliver more charges to neural tissues while under electrochemical safety limits. Applying anodic bias potential during neurostimulation is a known technique for charge enhancement. Here, we investigated the levels of charge enhancement with anodic bias potential in vitro and in vivo using a custom-designed portable neurostimulator. We immersed our custom microelectrode probe in saline and measured voltage transients in response to constant current stimulation with and without a 500 mV anodic bias potential. We then inserted the same microelectrode probe into the primary motor cortex of the rat brain and measured voltage transients with the same electronics. Results showed that the charge injection capacity of the activated iridium oxide microelectrode site (with 2000 μm2 geometric surface areas (GSAs)) increased by the use of the anodic bias potentials in both in vitro and in vivo: from 10 nC/phase to 32 nC/phase for 200 μs pulse widths, and from 2 nC/phase to 8 nC/phase, respectively. Thus, the order of charge injection capacities of the four cases tested in this study is as follows (from the lowest to the highest): in vivo without anodic bias, in vivo with anodic bias, in vitro without anodic bias, and in vitro with anodic bias. This work also validated in vivo use of our new portable neurostimulator which received stimulation waveforms wirelessly.

Approach to Evaluation of Electrocatalytic Water Splitting Parameters, Reflecting Intrinsic Activity: Toward the Right Pathway.

The development of transition metal-based non-precious-metal electrocatalysts for energy storage and conversion systems has received a lot of interest recently. To further this subject in the proper way given the development of electrocatalysts, a fair comparison of their respective performance is necessary. This Review investigates the parameters used for the comparison of electrocatalyst activity. Significant evaluation criteria employed in electrochemical water splitting studies are the overpotential at defined current density usually at 10 mA per geometric surface area, Tafel slope, exchange current density, mass activity, specific activity and turnover frequency (TOF). This Review will discuss how to identify the specific activity and TOF by electrochemical and non-electrochemical methods to represent intrinsic activity as well as the benefits and uncertainties of each technique, ensuring that each method is applied correctly when calculating intrinsic activity metrics.

Study on the 4-channel micro-monolithic design with geometry control for reversible solid oxide cell

Reversible solid oxide cell (R-SOC) has been attracting considerable attention as a technology capable of power generation and CO2 electrolysis. In addition to new material development, innovation in structural design is also a decisive factor. In this study, a 4-channel micro-monolithic design, in the form of a tear-drop inner channel structure, was successfully developed. The micro-monolith obtained includes plurality of micro-channels growing from multiple directions and spongy active regions near the exterior surface. Uniquely, the irregular tear-drop inner channels further increase the proportion of the electrochemically active region to the overall circumference, achieving more efficient utilization of the geometric surface area. Such micro-structured cells with Ni-YSZ/YSZ/YSZ-LSM materials exhibited effective performance in the reversible operation of R-SOC. A superior performance of 1.20 W·cm−2 at 800 ℃ for H2 fuel cell was demonstrated. Similarly, during the electrolysis of CO2, current density recorded by the cells reached 1.20 A·cm−2 at 1.5 V and 800 ℃, which is competitive compared with the values of the previous design investigations. Relatively low diffusion polarization shown in electrochemical impedance spectroscopy (EIS) suggests that this is due to the very gas transfer resistance in the fuel electrode. This novel multi-channel micro-monolithic structure shows a potential to substitute the conventional tubular counterpart.

Formate Over-Oxidation Limits Industrialization of Glycerol Oxidation Paired with Carbon Dioxide Reduction to Formate.

Electrocatalytic CO2 reduction processes are generally coupled with the oxidation of water. Process economics can greatly improve by replacing the water oxidation with a more valuable oxidation reaction, a process called paired electrolysis. Here we report the feasibility of pairing CO2 reduction with the oxidation of glycerol on Ni3 S2 /NF anodes to produce formate at both anode and cathode. Initially we optimized the oxidation of glycerol to maximize the Faraday efficiency to formate by using design of experiments. In flow cell electrolysis, excellent selectivity (up to 90 % Faraday efficiency) was achieved at high current density (150 mA/cm2 of geometric surface area). Then we successfully paired the reduction of CO2 with the oxidation of glycerol. A prerequisite for industrial application is to obtain reaction mixtures with a high concentration of formate to enable efficient downstream separation. We show that the anodic process is limited in formate concentration, as Faraday efficiency to formate greatly decreases when operating at 2.5 M formate (∼10 w%) in the reaction mixture due to over-oxidation of formate. We identify this as a major bottleneck for the industrial feasibility of this paired electrolysis process.

Determination of Engineering Properties of Coleus Pertinent to the Design of a Digging-cum-Windrowing Unit

Coleus (Solenostemon rotundifolius) is an important minor tuber crop grown in the homesteads of Kerala and Tamil Nadu. There was a demand for mechanisation for harvesting the tuber because the conventional method of harvesting followed was tedious and time-consuming. For the design and development of a coleus harvester with reduced drudgery, the design parameters were selected with respect to the tuber properties. Random sampling was carried out for determining the physical and frictional properties of coleus. The average values of physical properties such as length, width, thickness, geometric mean diameter, sphericity, surface area, volume and bulk density were found out as 44.56 mm, 27.36 mm, 24.50 mm, 30.99 mm, 0.70, 3029.69 mm2, 15786.50 mm3 and 718.21 kg m-3 respectively. The angle of repose was determined as 30.83° and the coefficient of static friction was found out as 0.73, 0.69 and 0.81 on galvanised iron, stainless steel and plywood surfaces respectively. These data were used for the design of various components of the harvester.

A cellular automata framework for porous electrode reconstruction and reaction-diffusion simulation

Due to the high charge transfer efficiency compared to that of non-porous materials, porous electrodes with larger surface area and thinner solid pore walls have been widely applied in the lithium-ion battery field. Since the capacity and charge-discharge efficiency of batteries are closely related to the microstructure of porous materials, a conceptually simple and computationally efficient cellular automata (CA) framework is proposed to reconstruct the porous electrode structure and simulate the reaction-diffusion process under the irregular solid-liquid boundary in this work. This framework is consisted of an electrode generating model and a reaction-diffusion model. Electrode structures with specific geometric properties, i.e., porosity, surface area, size distribution, and eccentricity distribution can be constructed by the electrode generating model. The reaction-diffusion model is exemplified by solving the Fick’s diffusion problem and simulating the cyclic voltammetry (CV) process. The discharging process in the lithium-ion battery are simulated through combining the above two CA models, and the simulation results are consistent with the well-known pseudo-two-dimensional (P2D) model. In addition, a set of electrodes with different microstructures are constructed and their reaction efficiencies are evaluated. The results indicate that there is an optimum combination of porosity and particle size for discharge efficiency. This framework is a promising one for studying the effect of electrode microstructure on battery performance due to its fully synchronous computation way, easy handled boundary conditions, and free of convergence concerns.

Physiological Response of Stored Pomegranate Fruit Affected by Simulated Impact

Mechanical damage resulting from excessive impact force during handling and other postharvest operations from harvesting to consumption is a critical quality problem in fresh produce marketing. The study investigates the impact of bruise damage, storage temperature, and storage period on the physiological responses of Omani pomegranate fruit cultivar 'Helow'. Fruits were subjected to low (45°; 1.18 J) and high (65°; 2.29 J) impact levels using a pendulum test by hitting the fruit on the cheek side. Bruised and non-bruised fruit were stored at 5 and 22 °C for 28 days. Bruise measurements, water loss per unit mass, water loss per surface area, firmness, fruit size measurements, geometric mean diameter, surface area, fruit volume, color parameters, respiration rate, and ethylene production rate were evaluated. Bruise area, bruise volume, and bruise susceptibility of damaged pomegranate fruit were increased as impact level, storage duration, and storage temperature increased. Pomegranates damaged at a high impact level and conditioned at 22 °C showed 20.39% weight loss on the last day of storage compared to the control and low-impact-bruised fruit. Firmness and geometric mean diameter were significantly (p < 0.05) reduced by bruising at a high impact level. Impact bruising level and storage temperature decreased lightness, yellowness, browning index, and increased redness over time. Furthermore, the respiration rate was five times higher in the non-bruised and low- and high-impact-injured fruit stored at 22 °C than that stored at 5 °C. The ethylene production rate recorded its highest value on day 21 in high-level-impact-bruised pomegranate fruit. The bruise susceptibility was strongly correlated with the majority of the studied parameters. This study can confirm that bruising can affect not only the visual quality characteristics but also the physiological attributes of pomegranate fruit; therefore, much care is required to preserve fresh produce and avoid any mechanical damage and losses during postharvest handling.

Dynamic biomass char porosity during gasification: Model compared with data

This investigation presents a new biomass char porosity model as a function of char conversion during gasification and compares it with entrained-flow data from poplar, corn stover and switchgrass particles reacting with H2O, CO2, and combinations of both at temperatures of 1050–1350 °C. The experimental data include particle temperature, mass, size, and shape combined with porosity, BET surface area, geometric specific surface area and SEM images of char vascular structure. The new theoretical model describes char porosity changes during char conversion and the model indicates that porosity increases monotonically, consistent with the data. The vascular char structure remains intact even at the highest conversions and this structure effectively transports reactants and products through the particle, with reactions occurring on the walls of these vascular vessels, referred to here as vascules. The investigation shows that char porosity most strongly depends on average vascule diameter which, in turn, increases with increasing conversion. This investigation extends current understanding of the mechanism of heterogeneous biomass char reactions (gasification and oxidation) under kinetically controlled conditions. This work concludes that (1) kinetically controlled biomass gasification involves reactions on the walls of vascules with small contributions from the nanopores or even mesopores; (2) char porosity increases monotonically with increasing char conversion in the kinetically and internal transport-controlled regimes; and (3) observed porosity behaviors correspond the predicted behaviors.

Determining the Geometric Surface Area of Mesoporous Materials

Specific surface area is an important property of porous materials and a crucial index in multiple disciplines, which is mainly measured using nitrogen isotherms and the Brunauer–Emmett-Teller (BET) equation. The BET surface area is remarkably higher than the geometric surface area, which is defined as the surface area of the crystal geometry structure. However, many studies directly use the BET surface area as the geometric surface area. We proposed a simple, general, and accurate method that only needs the nitrogen adsorption isotherm as the input to calculate the geometric surface area of mesoporous materials. The proposed method considers the adsorptive potential influences and the physical state of adsorbed nitrogen in estimating the surface area. We utilized 18 isotherms generated by molecular simulations and actual experiments to cover a wide range of materials, including minerals, catalysts, and carbon-based tubes, and validate the effectiveness of the proposed method. Our results showed that the surface area determined by the proposed method is almost identical to the referenced geometric area. The surface area obtained by the proposed method can be typically considered a geometric surface area.