bluuebunny/crossref_metadata_2025 huggingface dataset:
Low-Temperature Processed Metal-Semiconductor Field-Effect Transistor with In–Ga–Zn–O Channel Deposited by Ar+O2+H2 Sputtering
Authors: Magari Yusaku , Furuta Mamoru
Published: September 2020

We investigated the electrical properties of metal-semiconductor field-effect transistors (MES-FETs) with a stacked channel consisting of hydrogenated In–Ga–Zn–O (IGZO:H) on conventional IGZO (IGZO). The IGZO and IGZO:H films were deposited by Ar+O2 and Ar+O2+H2 sputtering, respectively. The maximum process temperature is 150°C. By applying the IGZO:H/IGZO stacked channel, the on-current of the MES-FET drastically improved compared to the IGZO single-channel, and it exhibited the on-off current ratio of 4.2×108 and subthreshold swing of 155 mV/decade. It was found that diffused hydrogen from IGZO:H to IGZO layer increased electrons up to 1.5×1019 cm-3 near the IGZO:H/IGZO interface. Moreover, the increased electrons confined at the IGZO:H/IGZO interface to form a pseud two-dimensional electron gas because the conduction band offset of 0.18 eV is formed at the IGZO:H/IGZO interface. Thus, the presence of both of the conduction band offset and hydrogen diffusion plays an important role in the MES-FETs performance.
Effect of Glass Substrate on the Film Properties of Poly Silicon by Excimer Laser Annealing
Authors: Zhu Bin , Vaddi Rajesh , Huang Ming-Huang , Kim Hoon , Manley Robert G.
Published: September 2020

This work studies the effect of glass substrate thermal properties on the crystallization behavior and surface topography of polycrystalline silicon (p-Si) films formed by a XeCl excimer laser annealing of amorphous silicon. 60 nm hydrogenated amorphous silicon (a-Si:H) film was deposited on different glass substrates of varying thermal properties. A 300 nm SiO2 buffer layer was in between the glass and the silicon film. The silicon was crystallized by a XeCl excimer laser. The film properties of p-Si exhibit a small relationship with the glass substrate thermal properties. The higher thermal conductivity of glass retards the poly-Si <111> texture and reduced the residual tensile stress. The higher thermal diffusivity of the glass substrate causes a decline in the p-Si <111> texture, the surface asymmetry, and flatness.
Influence of Glass Surface Modification on Thin Film Copper Electrodes
Authors: Huang Ming-Huang , Shi Ying , Zhu Bin , Vaddi Rajesh , Kim Hoon , Manley Robert G.
Published: September 2020

We investigate the impact of the glass surface on the structural and electrical properties of Ti/Cu film stacks as well as single Ti adhesion layer, by modifying Corning® Eagle XG® glass surfaces using four acids common in TFT-LCD microfabrication processes. Atomic force microscopy results indicate significant change of the surface topography of Ti and Cu, particularly found on hydrofluoric acid treated glass surfaces. The film microstructures are characterized by a comprehensive analysis using Bragg, grazing incidence and in-plane X-ray diffraction, and X-ray reflectivity methods as well as the transmission electron microscopy. The sheet resistance was measured using the four-point probe method. We demonstrate the role of the glass surface state through its impact on the structural and electrical properties of Ti/Cu electrodes emanating from glass surface treatments.
Flash Lamp Annealed LTPS TFTs with ITO Bottom-Gate Structures
Authors: Packard Glenn , Rosenfeld Adam , Manley Robert G. , Hirschman Karl D.
Published: September 2020

A study on bottom-gate PMOS TFTs built on flash lamp annealed polycrystalline silicon is presented. As an alternative to top-gate devices, bottom-gate TFTs offer potential benefits in dielectric-semiconductor interface quality due to process integration details of crystallization and defect passivation. Indium Tin Oxide was used as the gate electrode material due to its attractive optical and electrical properties, thermal stability, and compatibility with the FLA process. Details of an experimental design used to investigate combinations of FLA and furnace annealing for a-Si crystallization and dopant activation processes will be discussed. ITO Bottom-gate TFTs fabricated with FLA crystallization followed by boron ion implantation and furnace activation exhibited superior electrical characteristics in comparison to other treatments. A comparison of electrical characteristics measured on bottom-gate and double-gate devices is used to develop an interpretation of defect effects and provide a qualitative assessment of interface states.
(Invited) Percolation Carbon Nanotube Thin Film Transistors
Authors: Shur Michael , Park Junsung , Zhang Yuhui , Liu Xueqing , Ytterdal Trond
Published: September 2020

Carbon Nanotube (CNT) Thin Film Transistors use the CNT mats forming a random percolating network. The conduction contacts between the individual CNTs are determined by tunneling and are strongly affected by external agents, such as gases or biological fluids. The asymmetry of the contacts to each CNT enables the rectification of electromagnetic radiation impacted on the CNT mat with giant relative changes near the percolation point. Our experimental data show that sub-THz radiation shifts the percolation point at high intensity, when the rectified radiation changes the shape of the potential barrier between the CNT in a proximity contact. We now propose to operate the CNT Thin Film Transistors near the percolation point, where the gate bias shifts the percolation point by changing the shape of the CNT contact tunneling barriers. This ensures a sharp decrease of the subthreshold current slope.
(Invited) Sub-40mV Sigma VTH Igzo nFETs in 300mm Fab
Authors: Mitard Jerome , Kljucar Luka , Rassoul Nouredine , Dekkers Harold F. W. , van Setten Michiel , Chasin Adrian , Pourtois Geoffrey , Belmonte Attilio , Delhougne Romain , Donadio Gabriele Luca , Goux Ludovic , Nag Manoj , Wilson Chris , Tokei Zsolt , Borniquel Jose Ignacio del agua , Steudel Soeren , Kar Gouri Sankar
Published: September 2020

Back and double gate IGZO nFETs have been demonstrated down to 120nm and 70nm respectively leveraging 300mm fab processing. While the passivation of oxygen vacancies in IGZO is challenging with an integration of front side gate, a scaled back gated flow has been optimized by multiplying design of experiments around contacts and material engineering. We then successfully demonstrated sub-40mV σ(VTH_ON) in scaled IGZO nFETs. Regarding the performance and the VTH_ON control, a new IGZO phase is also reported. A model of dopants location is proposed to better explain the experimental results reported in literature.
(Invited) Hafnia Ferroelectric Device for Semiconductor, Sensor, and Display Applications
Authors: Jeon Sanghun
Published: September 2020

For the ferroelectric material with the conventional perovskite crystal structure and the chemical formula of ABO3, the charge neutral level is located close to the conduction band edge, and when forming a device, it causes a high leakage current due to low Schottky barrier height. Therefore, a relatively thick ferroelectric thin film was required, which was not suitable for the existing CMOS technology that is evolving through miniaturization. Meanwhile, ferroelectric properties were discovered in hafnia in 2011, and the ferroelectric properties of hafnia is observed in an orthorhombic crystal structure. Due to its simple structure and excellent CMOS process compatibility, it has received much attention for ferroelectric hafnia thin films and various application technologies using them. In this report, we will look at various application technologies using hafnia ferroelectrics, and we will examine the characteristics of hafnia ferroelectrics suitable for each device.
P3HT:ZnS Based Photovoltaic Devices with Enhanced Performance Assisted by Oxidised Carbon Nanotubes
Authors: Wei Chaohui , T. Bishop Matthew , Wang Yifei , Gao Fei , Wang Chenxu , Chen George Zheng
Published: September 2020

Photovoltaic devices based on P3HT:ZnS bulk heterojunctions currently produce relatively low efficiencies. This work aims to produce a novel photoactive layer, by incorporating oxidised carbon nanotubes (CNTs) into a P3HT:ZnS bulk heterojunction. It was found that the mildly oxidised CNTs (LowOx-CNTs) were longer in length compared to the higher oxidised CNTs (HighOx-CNTs). Due to the reduced conductivity of the HighOx-CNTs, 5 and 10 wt% of HighOx-CNTs performed worse at lower levels than that of the LowOx-CNTs, with the most notable difference at 5 wt% (0.0064% and 0.0096%, respectively). As the load of the CNTs increased, the FFs for both devices decreased and the Jsc values began to plateau at roughly 0.15 mA/cm2. The introduction of CNTs increases the efficiency of the undoped ZnS device by more than 7 times, which can be further increased with the incorporation of electron and hole transporting layers.
(Keynote) Conduction and Photoconduction in Fullerene- and Porphyrin-Containing Metal-Organic Framework Thin Films
Authors: Heinke Lars
Published: September 2020

Photoconductivity is a characteristic property of semi-conductors, enabling various applications such as photoresponsive transistors and light-sensing. Some crystalline metal-organic framework, MOF, composed of functional organic components show interesting photoconduction properties. Here, we compare the light-responsive conductivity of four different MOF thin films with similar structure, but different compositions, possessing C60 fullerene and porphyrin or phenyl moieties. The results show that the embedment of fullerene, as well-known n-conducting component, increases the conductivity but shows little photo-response. While the total conductivity values are small, the conduction in the porphyrin sample shows noticeable photo-response, in particular when exciting the Soret band with blue light. Taking advantage of donor-acceptor interactions, the combination of C60 and porphyrin in close proximity of the MOF structure, results in thin films with strong photo-response and conductivities increased by 2 orders of magnitude upon blue light irradiation.
(Invited) Nanostructured Conjugated Materials in Metal-Organic Frameworks
Authors: Kitao Takashi , Uemura Takashi
Published: September 2020

Understanding the properties of a few conjugated polymer chain assemblies is important because of their potential applications for molecule-based devices. The regulated and tailor-made pore characteristics of metal–organic frameworks (MOFs) allow the achievement of precise molecular assemblies in the nanochannels, which has shed light on the unique properties of polymers. In addition, the encapsulation of functional polymers in MOFs can lead to host–guest synergies and provide novel nanohybrid materials that exhibit intriguing properties that are hard to achieve with the individual components.
(Keynote) Electromagnetic Field Stimulated MOFs
Authors: Knebel Alexander , Chen Donghui , Hosseinimonjezi Bahram , Santos Jaciara C. C. , Redel Engelbert , Caro Jürgen , Volkmer Dirk , Wöll Christof
Published: September 2020

Metal-Organic Frameworks, consisting of inorganic nodes and organic linker molecules, are (mainly) porous materials with record holding inner surface areas, tailor-made properties, and adjustable pore windows. External stimuli on MOFs can be applied and achieve control over crystallization, gas transport properties, pore windows, and many other effects: breathing, dipolar moment, etc., which is extremely interesting for membrane science.The keynote will present an overview on novel types of applied physics to membrane separations to enhance green production and carbon capture: we can use novel MOF materials as porous liquids or MOF thin films and influence their properties with external stimuli, such as electromagnetic fields. This leads to interesting interactions: adsorption and desorption can be changed, as well as an in-situ control over the continuous gas separation on the nanometer scale can be done through membrane layers.
(Invited) 3D Neural Network: Monolithic Integration of Resistive-RAM Array with Oxide-Semiconductor FET
Authors: Kobayashi Masaharu , Wu Jixuan , Mo Fei , Saraya Takuya , Hiramoto Toshiro
Published: September 2020

We have developed monolithic integration of RRAM array and oxide semiconductor channel access transistor in 3D stack, achieved uniform memory characteristics of 1T1R cells at each layer, and demonstrated basic functionality of XNOR operation as in-memory computing for binary neural network AI applications. The impact of RRAM bit error rate on neural network is also investigated. 3D neural network built by this architecture enables area-efficient, low-power and low-latency computing in machine learning accelerator.
First-Principles Study of Defect Levels Caused by Transition Metal Atoms in Silicon Nitride for Non-Volatile Memory Applications
Authors: Agrawal Rahul , Kobayashi Kiyoteru
Published: September 2020

We have analyzed the nature of the transition metal (Ti, V, or Mn) defects in β-silicon nitride using first-principles calculations. Three supercells consisting of 168 atoms, termed as Si71N96Ti, Si71N96V, and Si71N96Mn, were derived from the supercell Si72N96 by substituting a Si atom with a transition metal atom. The density of states (DOS) were calculated for all the supercells. In Si71N96Mn, several defect levels appeared in bandgap. Some of the defect levels are energetically deep. Atomic Layer DOS (ALDOS) calculations have confirmed the localization of the defect levels around the Mn atom. Some of the defect levels would be able to behave as deep electron trap sites. Several defect levels also appeared in the supercell Si71N96V. On the other hand, in Si71N96Ti, no deep defect levels appeared in the bandgap.
Finite Element Model Based Determination of Local Membrane Conductivity of Polymer Electrolyte Fuel Cells
Authors: Schuller Arnaud , Eller Jens
Published: September 2020

A new non-invasive method to measure PEFC in-plane membrane conductivity distribution is presented. It is based on electrical impedance tomography that relies on surface current injection and voltage measurement at the outer cell surface. The working principle is detailed and a numerical feasibility study shows the potential of the technique.
Measurement and Analysis of Gas Transport Properties in Catalyst Layers of Polymer Electrolyte Fuel Cells with Different Ionomer to Carbon Ratio
Authors: Tsutsui Fumiaki , Suzuki Takahiro , Tsushima Shohji
Published: September 2020

Gas transport properties in catalyst layers of polymer electrolyte fuel cells are key factors for improving cell performance. It is necessary to clarify the relationship between the gas transport properties and the microstructure in catalyst layers. In this study, the oxygen diffusivities in catalyst layers with different ionomer-to-carbon ratio (I/C) were evaluated using a microfluidic device, and tortuosity factors were obtained. The porous structures of catalyst layers were evaluated by the nitrogen physisorption method and observation using a field emission scanning electron microscope. It was revealed that the tortuosity factor of the catalyst layers with high and low I/C was larger than that of catalyst layers with middle I/C. This can be attributed to the segregation of ionomers in high-I/C catalyst layers and the agglomeration of carbon particles in low-I/C catalyst layers.
Fabrication and Evaluation of Catalyst Layers in Polymer Electrolyte Fuel Cells: A Comparison of Decal and Inkjet Printing Techniques
Authors: Shimizu Yuki , Murata Ryosuke , Kokogawa Riho , Suzuki Takahiro , Tsushima Shohji
Published: September 2020

Controlling the porous structure of the catalyst layer in polymer electrolyte fuel cells (PEFCs) is one of the challenges to improve the performance of PEFCs. In this study, we focused on an inkjet printing technique as a catalyst layer fabrication method utilized to elucidate the relationship between cell performance and the microstructure of the catalyst layer. A catalyst layer was prepared using an inkjet printer with a single nozzle, and the cell performance was examined. For comparison, the performance of the catalyst layer fabricated by the decal transfer technology was investigated. The catalyst layer prepared by the decal transfer method showed its better performance under the air supply condition, while the catalyst layer made by the inkjet printing technique was better under the oxygen supply in both low- and high-humidity conditions.
Optimizing the Composition of the PEMFC Catalyst Layer
Authors: Lamb James , Andrei Petru
Published: September 2020

In this article we perform a full microstructure optimization of the catalyst layer in proton exchange membrane fuel cells by computing the optimum distributions of the platinum particles, nafion and carbon. Our approach is based on evaluating the sensitivity functions of the cell voltage under specified current conditions and using these sensitivity functions in a gradient-based optimization algorithm design to converge towards the optimum microstructure of the cell. Since the optimization requires finding the combined optimum distributions of the platinum particles, nafion and carbon, our approach requires the calculation of all three sensitivity functions, which are related to the Gâtaux derivatives of the discharge voltage with respect to the design variables. We find that it is optimum to increase the density of the platinum particles and the amount of the electrolyte near the membrane side of the catalyst layer and, at the same time, increase the porosity and carbon fraction near the gas diffusion layer.
Distribution of Relaxation Time Analysis of Cathode Micro-Patterned PEFC
Authors: Tomizawa Morio , Nagato Keisuke , Nagai Kohei , Nakao Masayuki
Published: September 2020

Previous studies have shown that cathode micro-patterned polymer electrolyte fuel cells (PEFCs) effectively improve its performance because of the increase in chemical reaction surface. However, the mechanism of performance improvement is still unclear. Patterning can decrease mass transport (especially gas transport) because the diffusion path increases. Distribution of relaxation time (DRT) analysis can deconvolute impedance spectra and investigate the dependency of polarization resistance on each physical phenomenon. We performed DRT analysis using a patterned PEFC and found that it behaved similar to a conventional flat PEFC. Further experiments can reveal the difference between patterned and conventional PEFCs and quantify the effect of patterning.
Understanding Degradation Phenomena in HT-PEM Fuel Cells Using Micro-Computed Tomography
Authors: Schmies Henrike , Schonvogel Dana , Büsselmann Julian , Wagner Peter , Dyck Alexander
Published: September 2020

An extended and reliable lifetime of high temperature proton exchange membrane fuel cells is inevitable for the commercialization of this technology in the near future. Therefore, components of the high temperature-proton exchange membrane fuel cell (HT-PEMFC), such as the bipolar plates (BPPs) and the membrane electrode assembly (MEA), are investigated regarding degradation phenomena during constant cell operation with use of contaminated air in the cathode feed. µ-computed tomography (µ-CT) is applied to visualize morphological changes due to this operation and to analyse each component individually on the micro meter scale. The thickness of each MEA layer is determined and correlated to results from electrochemical measurements. Furthermore the open porosity of the bipolar plates is determined and compared to phosphoric acid retention of the cell.
Failure Analysis and Defects Characterization of Polymer Electrolyte Membrane Fuel Cells after Relative Humidity Cycling
Authors: Soleymani Amir Peyman , Chen Jixin , Ricketts Mark , Waldecker James , Jankovic Jasna
Published: September 2020

Commercial catalyst coated membrane (CCM) was tested under a relative humidity (RH) cycling accelerated stress test (AST). The morphology around the failed regions, identified by the bubble jig test, were examined by scanning electron microscopy (SEM), scanning transmission electron microscopy-energy dispersive spectroscopy (STEM-EDS), and X-ray computed tomography (XCT) and compared with beginning of life (BOL) sample. The SEM images showed the defects in forms of catalyst layer (CL) and membrane cracks, delamination, and bulging along with CL thickness alterations. The XCT scans confirmed the presence of circular and volcano-shape defects protruded throughout the CCM, as well as MPL irregularities. Defects were correlated to the morphology of the microporous layer (MPL), suggesting that MPL structure may affect the degradation of CCMs. The STEM-EDS microstructural evaluations and analysis revealed changes in the CL porosity with respect to the BOL, confirming the thickness changes and defect formation observed in SEM and XCT.
Water Balance Measurements for a Single Proton Exchange Membrane Fuel Cell Using a Hot Wire Anemometer
Authors: Al Shakhshir Saher , Berning Torsten
Published: September 2020

Recently, our group has developed a novel technique to measure the water balance in a proton exchange membrane fuel cell with a hot wire anemometer. This device yields a high-frequency voltage signal that can be converted into the fuel cell water balance, and thus producing almost real time water balance data that can complete the usual experimental data set consisting of cell voltage, current, and high frequency resistance. In this work, we are presenting water balance data of a single 50 cm2 fuel cell with pre-humidified anode and cathode streams. The results show a clear tendency of anode dehydration at elevated current densities which appears to be limiting the current density that can be drawn from the cell.
Determination Method of Dimensionless Moduli for Estimation of PEFC Performance
Authors: Kageyama Miho , Yamaguchi Kazuhiro , Heggo Dalia , Ma Yulei , Ogawa Hikaru , Kawase Motoaki
Published: September 2020

To predict PEFC performance without complicated simulation or a lot of experimental data is required for the optimum design of the cell, especially the cathode catalyst layer (CCL). In our previous study, the effectiveness factor of CCL was reported to be a function solely of 4 dimensionless moduli which were derived from the isothermal one-dimensional model of the cathode consisting of oxygen balance, oxygen transport, proton transport, reaction stoichiometry, and rate. In this study, the dependency of the oxygen reduction reaction (ORR) rate on CCL thickness is analyzed and a method to determine dimensionless moduli is proposed.
Acoustic Emission Analysis of Polymer Electrolyte Membrane Fuel Cells
Authors: Bethapudi Viswanath Sasank , Hinds Gareth , Shearing Paul R. , Brett Dan , Coppens Marc -Olivier
Published: September 2020

The performance of a polymer electrolyte membrane fuel cell (PEMFC) is characterized using acoustic emission (AE) based analysis. Polarization scans indicate that an increase in cell temperature from 45°C to 60°C results in a drop in maximum current density due to cell dehydration. Parametric analysis of acoustic activity generated from the PEMFC during polarization establishes a relationship between the cell operating conditions and the corresponding AE generated. Optimal and dehydrated cell conditions result in stable and reduced numbers of generated acoustic events, respectively, which are related to the flow of water and its physical state in the flow-fields. Furthermore, the AE parameters utilized for hydration analysis are amplitude and counts, which correspond to intensity and proportion of AE generated beyond a threshold, respectively; these are influenced by current density, reactant humidity, and cell temperature.
Microscopy Studies of the Catalyst Inks for PEM Fuel Cells
Authors: Pedram Sara , Macauley Natalia , Zhong Sichen , Xu Hui , Jankovic Jasna
Published: September 2020

The microstructure of the catalyst layer in proton exchange membrane fuel cells (PEMFC) is one of the key factors that determine fuel cell performance. The ink preparation, including dispersion solvent, mixing time, and mixing power, are among the less reported parameters that would influence the ionomer distribution on the catalyst surface and the continuity of the carbon network. In this work, novel characterization approaches have been used to investigate the effect of the Pt/C catalyst ink preparation conditions on the morphology and structures of the catalyst layer. Microscopy analysis revealed that longer mixing time led to better performing electrode structures than shorter mixing time. The longer mixing time enabled improved continuity of the ionomer network and high porosity in the cathode layer that contributes to improved proton conductivity and mass transport. This has been reflected in performance and durability tests, where the electrode made from a 5-day catalyst ink displayed improved performance compared to the one made from a 3-day ink. Durability studies showed 26% and 43% loss of the initial mass activity for 5 days and 3 days mixing, respectively. In addition, the catalyst layer prepared with ethylene glycol as the dispersion solvent showed better durability than water/1-propanol based solution.
(Invited) Factors Influencing the Performance of Vanadium Flow Batteries: Electrodes and Electrolytes
Authors: Buckley D. Noel , Bourke Andrea , Oboroceanu Daniela , Quill Nathan , Lenihan Catherine , Al-Hajji Safi Maria , Miller Mallory A. , Savinell Robert F. , Wainright Jesse S. , Lynch Robert P.
Published: September 2020

The electrochemical kinetics of the VII-VIII reaction on carbon electrodes is enhanced by anodic treatment and inhibited by cathodic treatment. In contrast, the kinetics of VIV-VV is inhibited by anodic treatment and enhanced by cathodic treatment. Rate constants are greater for VIV-VV than for VII-VIII under comparable conditions. The observed effects are attributed to oxygen-containing species on the surface of carbon electrodes and it is likely that enhancement of both VII-VIII and VIV-VV is due to the same (active) state of the electrode. Oxidation of this active state leads to inhibition of VIV-VV while reduction of the same active state leads to inhibition of VII-VIII. Using our standard methodology, we investigated the thermal stability of VFB catholytes. We showed that the induction time for precipitation of V2O5 decreases exponentially with increasing temperature or VV concentration but increases exponentially with increasing sulphate concentration. Arrhenius plots show two linear regimes, at 45–70°C and 30–45°C, respectively. We model this to estimate acceleration factors for testing of electrolyte stability over a range of test and use temperatures. Both arsenate and phosphate are effective additives for improving the thermal stability of VFB catholytes.
Automotive Cold Start of a PEMFC System by Using a Methanol Solution as Antifreeze
Authors: Montaner Rios Gema , Schirmer Johannes , Becker Florian , Bleeck Stefan , Gentner Christoph , Kallo Josef
Published: September 2020

The startup ability and durability at winter conditions has been a key issue for fuel cell vehicles. To reduce ice formation and to improve the cold start and lifetime of the PEMFC system, the remained water is commonly purged with dry gases at shutdown. This paper proposes an alternative cold storage method based on the use of a methanol solution as antifreeze. In order to study the cold start ability of a PEMFC system by using this method, cold start experiments at -10°C were performed with a 4 kW PEMFC stack. The results show that the stack can be successfully started at -10°C after being stored with the methanol solution and after these cold starts no performance degradation was observed. Furthermore, the use of the antifreeze method at shutdown may reduce its time and improve the energy efficiency of the system.
A Computational Fluid Dynamics Analysis of Heat Transfer in an Air-Cooled Proton Exchange Membrane Fuel Cell with Transient Boundary Conditions
Authors: Lind Alexander , Yin Chungen , Berning Torsten
Published: September 2020

Turbulence-inducing grids can enhance heat transfer in air-cooled proton exchange membrane fuel cells and help to increase the fuel cell performance. In this computational fluid dynamics analysis, the distance between the turbulence grid and the cathode inlet was first varied, and then a transient sinusoidal inlet velocity around the previously investigated steady-state inlet velocity was applied because the heat transfer coefficient is known to increase in pulsating flow. Results indicate that the best distance between the grid and the cathode inlet is the closest at 2.5 mm, which is in good agreement with prior experiments. The transient effects are small but show an additional cooling effect.
Applications of Artificial Intelligence for Analysis of Two-Phase Flow in PEM Fuel Cell Flow Fields
Authors: Santamaria Anthony D. , Mortazavi Mehdi , Chauhan Vedang , Benner Jingru , Philbrick Oliver , Clemente Riccardo , Jia Hongfei , Ling Chen
Published: September 2020

This work probes the use of machine learning to uncover complex relationships between liquid phase behavior and pressure drop in polymer-electrolyte fuel cell reactant channels. Using a supervised decision tree (DT) regression algorithm, the liquid distributions in an ex-situ experimental reactant channel are correlated to the two-phase pressure drop for a range of air flow rates. Liquid phase distribution data collection is accomplished by capturing 2D images via a CCD camera of a transparent flow channel simulating polymer-electrolyte fuel cell conditions. Pressure transducers measure pressure drop along the length of the channel and are synchronized with the image collection. The images are processed for noise reduction and feature extraction and then used with pressure data for training. Overall, the DTs predict pressure drop using liquid distributions as inputs at rates exceeding 88.9% accuracy and were able to capture complex behavior such as pressure changes due to breakup of liquid slugs.
Investigation of Multilayered Catalyst Layers for Polymer Electrolyte Fuel Cells by Electrospray Deposition
Authors: Arai Hikaru , Irita Masaru , Katayama Noboru
Published: September 2020

In this study, multilayered catalyst layers with ionomer/carbon ratio (I/C ratio) were formed using electrospray deposition (ESD). The formed catalyst layer was used as the cathode of proton exchange membrane fuel cells (PEMFCs) for polarization measurements and electrochemical impedance measurements. The structures were observed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), and the maximum power densities for the homogeneous and three-layer catalyst layers at 100% MEA humidity were 274 mW/cm2 and 312 mW/cm2, respectively, indicating the effectiveness of the multilayered catalyst layer in ESD. SEM-EDS observations showed that larger aggregates were observed at higher I/C ratios, which also affected the thickness of the layers, suggesting that multilayered I/C ratios may be accompanied by multilayered physical structures.
Comparison of Planar and Tubular Flow Field Plates for Proton Exchange Membrane Fuel Cells (PEMFCs) through Simulation
Authors: Tang Aubrey Yu , Jankovic Jasna , Crisci Louis , Pedram Sara
Published: September 2020

Proton exchange membrane fuel cells are excellent clean energy alternatives to current non-renewable energy sources. Bipolar plates are a key component of these fuel cells and directly responsible for their performance. Traditional bipolar plates are created in a planar form, but recent research has revealed a novel tubular design that performs similarly to conventional plates. This study compares traditional planar designs with tubular ones. The finite element ANSYS software was used to determine and visualize velocity and pressure distributions of fluid flow through the bipolar plate channels.
Modeling Synergistic Fuel Cell Membrane Degradation with Mitigating Effects of Cerium
Authors: Ehlinger Victoria Marie , Kusoglu Ahmet , Weber Adam Z.
Published: September 2020

During operation, polymer-electrolyte fuel cells undergo mechanical and chemical degradation, which behave synergistically and lead to accelerated membrane deterioration over time. This study builds upon previous modeling work on mechanical degradation, as described by a pinhole in the membrane, and chemical degradation mitigation by using cerium. By combining these two models, analysis can be carried out on the coupled degradation methods and how the mitigation effects of cerium disrupt the degradation cycle. The model results show how the presence of a pinhole in the membrane changes the distribution of cerium in the cell and modifies chemical degradation rates. In addition, the model shows how cerium affects the rate of pinhole growth by slowing down the rate of change in mechanical properties due to chemical degradation. Finally, the model shows how cerium modifies the mechanical and chemical degradation rates of the membrane under humidity- and voltage-cycling conditions.
Probing Membrane Degradation with Varying Catalyst Layer Thickness and Carbon Support
Authors: Spears André , Rockward Tommy , Mukundan Rangachary , Garzon Fernando H
Published: September 2020

Understanding membrane degradation continues to be of significant importance when studying fuel cell durability. Fuel cell performance and durability depends heavily on the membrane’s chemical and mechanical integrity. In Nafion® membranes, hydroxyl radicals are the primary cause of chemical membrane degradation as they attack the membrane’s polymer structure. Radical formation can ensue via peroxide decomposition at the cathode or gases reacting on Pt particles within the membrane. A previous research effort on membrane degradation as a function of ultra-low Pt loadings (≤ 0.1 mgPt cm-2) showed the degradation rate increases with Pt loading. This is most likely due to more heterogenous sites for radical formation. Manufacturing MEAs with ultra-low Pt loadings can yield thin, non-uniform catalyst layers. In this research effort we studied membrane degradation with ultra-low Pt loadings while varying catalyst layer thickness, I/C ratio, and types of carbon support.
Manufacturing Process of Electrode Films
Authors: Banas Charles Joseph , Aponte Bryan , Pasaogullari Ugur
Published: September 2020

Rotating disk electrode (RDE) experiments form a key experimental characterization technique for measuring electrocatalyst performance and durability. While standard RDE testing protocols have been documented, it has been noted that catalyst film quality can skew measurements. The impact of relative humidity on drying is studied in an effort to produce consistent, high quality catalyst films for RDE experiments, which shows that high quality catalyst films can be manufactured repeatedly in a controlled environment, such as inside an environmental chamber as described.
Synthesis and Characterization of Low Platinum-Cobalt Alloy Cathode Catalysts by Rapid Annealing and Quenching Method for Fuel Cell Applications
Authors: Furukawa Ryo , Rahman Md Mijanur , Kaneta Yasuo , Delgertsetseg Byambasuren , Ui Koichi , Takeguchi Tatsuya
Published: September 2020

Polymer electrolyte membrane fuel cell (PEFC) has tremendous attention due to its unique properties, such as low-temperature operation, high power density, and application of solid electrolyte. Therefore, it is considered as a reliable power sources for transport, residential, and portable applications. However, current PEFC designs encounter problems, such as materials compatibility, fabrication cost, performance degradation, and so forth. Much research has been conducted to enhance the performance and durability of PEFC by improving electrode in which Pt is commonly used. To further improve the performance of electrode, it is important to enhance the Pt catalyst utilization in the electrode. On the other hand, Pt is extremely rare and expensive, that limits the practical application and wide-scale commercialization of PEFC. Low Pt content catalyst and its alloy have great potential to overcome these limitations by lowering Pt consumption, while its high catalytic activity and durability can be maintained in the meantime. Herein we prepared PtCo/C alloys as cathode catalyst by rapid heating and quenching (RHQ) method to investigate the relationship between catalytic activity and annealing temperature. Annealing temperatures are changed from 600-900ºC to obtain highly-alloyed small particles. For comparison, commercial PtCo/C catalyst was used as reference. Analyses of the I-V characteristics obtained from PtCo/C catalysts and after ADT test reveal the highest catalytic activity and durability in the case of annealing at 900ºC. It is suggested that the high catalytic activity and durability of PtCo/C catalyst can be achieved by providing a high-alloy with smaller particle sizes.
Open-Source Satellite-Derived Solar Resource Databases Comparison and Validation for Indonesia
Authors: Harsarapama Anindio P. , Aryani Dwi Riana , Rachmansyah Dedy
Published: September 2020

Solar resource data derived from satellite imagery are widely available nowadays, either as an open-source or paid database. This article is intended to assess open-source databases, which cover the region of Indonesia. Here, four known solar resource databases, which spatially cover the Indonesian archipelago, have been used, namely, Prediction of Worldwide Energy Resource (POWER), Surface Solar Radiation–Heliosat-East (SARAH-E), CM SAF Cloud, Albedo, Radiation edition 2 (CLARA-A2), and SolarGIS. In addition, a minor portion of the Meteonorm database by Meteotest, around five sample points across Indonesia, has been assessed in terms of coherency to the four mentioned databases. Correlation coefficient and relative bias of the multiyear monthly mean annual cycle global horizontal irradiation (GHI) between pairs of databases are inspected. Three out of four databases are then validated through the available irradiation ground measurement data provided by the World Radiation Data Centre (WRDC). The correlation between each pair varies mostly between 0.7 and 1, which shows that the four databases to a certain extent agree on how the intermonthly variation would behave throughout the year. On the other hand, the validation result reveals that the three databases, i.e., POWER, CLARA-A2, and SARAH-E, are suffering from positive bias error ranging from 3% to 7%. Despite that fact, the correlation between measured and estimated values is still acceptable with SARAH-E showing the best performance among the three. Careful selections and adjustment enable the possibility of these databases to be utilized as a tool for depicting interannual and intermonthly variations of solar irradiation throughout the Indonesian archipelago.
Time Trends and Prognostic Factors for Overall Survival in Myxoid Liposarcomas: A Population-Based Study
Authors: Lansu Jules , Van Houdt Winan J. , Schaapveld Michael , Walraven Iris , Van de Sande Michiel A. J. , Ho Vincent K. Y. , Haas Rick L.
Published: September 2020

Background. The purpose of this study was to evaluate the overall survival (OS) and associated characteristics for patients with Myxoid Liposarcoma (MLS) over time in The Netherlands. Methods. A population-based study was performed of patients with primary localized (n = 851) and metastatic (n = 50) MLS diagnosed in The Netherlands between 1989 and 2016, based on data from the National Cancer Registry. Results. The median age of the MLS patients was 49 years, and approximately two-thirds was located in the lower limb. An association was revealed between age and the risk of having a Round Cell (RC) tumor. OS rates for primary localized MLS were 93%, 83%, 78%, and 66% after 1, 3, 5, and 10 years, respectively. The median OS for patients with metastatic disease at diagnosis was 10 months. Increasing age (Hazard Ratio (HR) 1.05, p=0.00), a tumor size >5 cm (HR 2.18; p=0.00), and tumor location (trunk HR 1.29; p=0.09, upper limb HR 0.83; p=0.55, and “other” locations HR 2.73; p=0.00, as compared to lower limb) were independent prognostic factors for OS. The percentage of patients treated with radiotherapy (RT) increased over time, and preoperative RT gradually replaced postoperative RT. In contrast to patients with localized disease, significant improvement of OS was observed in patients with metastatic disease over time. Conclusions. In this large nationwide cohort, tumor size and tumor location were independent prognostic factors for OS. Furthermore, a higher probability of an RC tumor with increasing age was suggested. An increased use of RT over the years did not translate into improved OS for localized MLS.
Meso-Complexity Computer Simulation Investigation on Antiexplosion Performance of Double-Layer Foam Aluminum under Pore Grading
Authors: Wang Zhen , Gu Wen Bin , Xie Xing Bo , Chen Yu Tian , Fu Lei
Published: September 2020

Foam aluminum is an energy-absorbing material with excellent performance. The interlayer composed of multiple layers of foam aluminum and steel plate has good antiexplosion ability. In order to explore the antiexplosion performance of double-layer foam aluminum under different porosity rankings and to reveal its microscopic deformation law and failure mechanism, three kinds of aluminum foams with a porosity of 80%, 85%, and 90% were selected to form six different structures. Based on the Voronoi algorithm, a three-dimensional foam aluminum generation algorithm with random pore size and random wall thickness was written by using the Python language and Fortran language. The three-dimensional mesoscopic model of double-layer closed-cell aluminum foam sandwich panel is established by using LS-DYNA and ABAQUS software. The explosion process was simulated, and the flow field movement of explosion shock wave of aluminum foam under different porosity rankings was analyzed. Two groups of aluminum foam were randomly selected for the explosion test and compared for the strain and compression. The test results are consistent with the simulation results, which verifies the correctness of the three-dimensional meso-model. The results show that when the porosity of the upper layer of aluminum foam is greater than that of the lower layer of aluminum foam, the sandwich structure of double-layer aluminum foam has a large compression and the bottom plate has a small displacement; it is not that the greater the compression amount of aluminum foam is, the better the antiexplosion and wave absorption ability is. When the aluminum foam reaches the ultimate load-bearing capacity, the aluminum foam transfers the load due to compaction, resulting in stress enhancement phenomena. Through the analysis of the compression amount, floor deformation, wave dissipation capacity, and energy ratio of aluminum foam, it is concluded that the antiexplosion wave absorption effect of the sandwich structure of aluminum foam with 80%/85% group is the best; the changes of porosity and cell wall are important factors affecting the energy absorption capacity of aluminum foam.
The Role of Peroxisome Proliferator-Activated Receptors (PPARs) in Pan-Cancer
Authors: Huang Runzhi , Zhang Jiaqi , Li Mingxiao , Yan Penghui , Yin Huabin , Zhai Suna , Zhu Xiaolong , Hu Peng , Zhang Jiaxin , Huang Ling , Li Man , Sun Zehui , Meng Tong , Yang Daoke , Huang Zongqiang
Published: September 2020

Peroxisome proliferator-activated receptors (PPARs) are members of nuclear transcription factors. The functions of the PPAR family (PPARA, PPARD, and PPARG) and their coactivators (PPARGC1A and PPARGC1B) in maintenance of lipid and glucose homeostasis have been unveiled. However, the roles of PPARs in cancer development remain elusive. In this work, we made use of 11,057 samples across 33 TCGA tumor types to analyze the relationship between PPAR transcriptional expression and tumorigenesis as well as drug sensitivity. We performed multidimensional analyses on PPARA, PPARG, PPARD, PPARGC1A, and PPARGC1B, including differential expression analysis in pan-cancer, immune subtype analysis, clinical analysis, tumor purity analysis, stemness correlation analysis, and drug responses. PPARs and their coactivators expressed differently in different types of cancers, in different immune subtypes. This analysis reveals various expression patterns of the PPAR family at a level of pan-cancer and provides new clues for the therapeutic strategies of cancer.
High JAK2 Protein Expression Predicts a Poor Prognosis in Patients with Resectable Pancreatic Ductal Adenocarcinoma
Authors: Song Yang , Tang Mei-Yue , Chen Wei , Wang Zhe , Wang Si-Liang
Published: September 2020

Background. Pancreatic ductal adenocarcinoma (PDAC) is one of the most fatal malignancies worldwide. The JAK/STAT signaling pathway is involved in pancreatic cancer tumorigenesis. However, the prognostic value of JAK2 expression in resectable PDAC is unclear. Method. In this study, we performed a clinicopathological analysis of 62 resectable PDAC cases with a primary focus on survival. JAK2 expression was examined by immunohistochemistry. The relationship between JAK2 expression and clinicopathological features and prognosis was analyzed. Results. Survival curve analyses revealed that high levels of JAK2 expression predict a poor prognosis in resectable PDAC patients. Multivariate analysis confirmed that JAK2 expression can predict the prognosis of PDAC. Conclusions. Assessment of JAK2 protein expression may be a promising method to predict prognosis in patients with resectable PDAC.
A Prognostic Model Based on PAM50 and Clinical Variables (PAM50MET) for Metastatic Hormone Receptor–positive HER2-negative Breast Cancer
Authors: Prat Aleix , Tsai Yi-Hsuan , Pascual Tomás , Paré Laia , Adamo Barbara , Vidal Maria , Brasó-Maristany Fara , Galván Patricia , Brase Jan Christoph , Rodrik-Outmezguine Vanessa , Johnston Stephen , Ciruelos Eva , Parker Joel S.
Published: September 2020

Purpose:

Predicting prognosis in HR+/HER2− metastatic breast cancer (MBC) might be clinically useful; however, no validated prognostic biomarkers exist in this setting to date.

Patients and Methods:

In phase III, EGF30008 trial, 484 patients with HER2− MBC who received letrozole and placebo or lapatinib were selected. PAM50 data, ECOG performance status, visceral disease, number of metastasis, biopsy type, and age were evaluated. A progression-free survival (PFS) Cox model was evaluated. The final model (PAM50MET) with a prespecified cutoff was validated in patients (n = 261) with HR+/HER2− advanced breast cancer (aBC) from BOLERO-2 (phase III trial that evaluated exemestane and placebo or everolimus).

Results:

In EGF30008, prognostic models with PAM50 plus clinical variables yielded higher C-index values versus models with only PAM50 or clinical variables. The PAM50MET model combined 21 variables: 2 PAM50 subtypes, basal signature, 14 genes, and 4 clinical variables. In EGF30008, the optimized cutoff was associated with PFS [HR = 0.37; 95% confidence interval (CI), 0.29–0.47; P < 0.0001] and overall survival (OS; HR = 0.37; 95% CI, 0.27–0.51; P < 0.0001). The median (months; 95% CI) PFS and OS were 22.24 (19.0–24.9) and not reached in PAM50MET-low versus 9.13 (8.15–11.0) and 33.0 (28.0–40.0) in PAM50MET-high groups, respectively. In BOLERO-2, the PAM50MET-low was associated with better PFS (HR = 0.72; 95% CI, 0.53–0.96; P = 0.028) and OS (HR = 0.51; 95% CI, 0.35–0.69; P < 0.0001). The median (months) (95% CI) PFS and OS were 6.93 (5.57–11.0) and 36.9 (33.4–NA) in PAM50MET-low versus 5.23 (4.2–6.8) and 23.5 (20.2–28.3) in PAM50MET-high groups, respectively.

Conclusions:

PAM50MET is prognostic in HR+/HER2− MBC, and further evaluation might help identify candidates for endocrine therapy only or novel therapies.