Ideal Channel Research Articles

High‐Performance Flexible Silicon Nanowire Field Effect Transistors on Plastic Substrates

AbstractInorganic semiconductor nanowires, known for their exceptional electronic properties and mechanical flexibility, are widely regarded as the ideal 1D channel materials for creating high‐performance flexible electronics. In this work, the integration of ordered arrays of silicon nanowire (SiNW) field effect transistors (FETs) directly onto flexible plastic substrates is showcased. The self‐aligned crystalline SiNW multi‐channels are first grown through an in‐plane solid–liquid–solid mechanism on rigid substrates, and then efficiently transferred in‐batch onto flexible polyethylene terephthalate (PET) plastics. The FETs constructed on these transferred SiNW channels exhibit outstanding performance, with a high on/off current ratio of >105, a low subthreshold swing of 175 mV dec−1, and remarkable mechanical stability that can endure an extremely small bending radius of 0.5 mm for 1000 cycles. Furthermore, inverter logics are also successfully demonstrated on plastic substrates, highlighting a prominent routine for scalable integration of high‐quality SiNW channels in the development of low‐cost, high‐performance flexible displays and wearable electronics.

Corporate social responsibility on social media: a scoping review of the literature

PurposeThe purpose of this study is to generate a better understanding of the nature of Corporate Social Responsibility (CSR) communication on social media. In fact social media are one of the most effective communication channels in contemporary business settings. Due to their inner characteristics, they should be the ideal channel for communicating CSR topics. Over the last 15 years, a variety of researches discussed the interplay between CSR and social media, resulting in a rather tangled body of knowledge.Design/methodology/approachThis study proposes a scoping review of published academic literature at the intersection of these two research bodies (i.e. CSR and social media communication) to shed light on the nature of the communication, strategic challenges and practices, as well as their key factors and impact.FindingsTo date, academic research related to the nature of CSR on social media is fragmented and blurry. This research sheds light on the challenges of interactive social media communication in CSR and presents an account of key strategies, tactics and possible impacts for these challenging communication practices.Originality/valueThis research generates a better understanding of the nature of CSR communication on social media, strategic challenges and practices, as well as their key factors and impact. It is the tentative of generating a synthetic account of relevant literature in the field.

High-density integration of uniform sub-22 nm silicon nanowires for transparent thin film transistors on glass

Ultrathin catalytical silicon nanowires (SiNWs), grown as orderly arrays upon glass substrates, are ideal 1D channels for the construction of high-performance field effect transistors for low-power and high aperture/transparency electronics. In this work, a rather uniform growth integration of high-density ultrathin SiNWs has been accomplished directly on glass substrate at 290 °C, via an in-plane solid–liquid-solid mechanism. The indium (In) catalyst thickness deposited on the dense guiding terrace steps was identified as a key parameter to suppress the size dispersion of the In droplets, and thus enable a uniform growth of ultrathin SiNWs with diameters down to DNW=21.8 ± 1.8 nm, a close-to-unity guided growth rate and an excellent transparency > 90 % in spectrum ranging from 350 nm to 950 nm. Based on a convenient dry plasma etching and low-temperature passivation procedure, high-performance SiNW transistors have been successfully fabricated upon a dense array of parallel SiNWs as channels with a narrow NW-to-NW spacing of 100 nm. A high current ratio Ion/Ioff > 107, a low off-state current down to 0.1 pA, a steep subthreshold swing of SS∼120 mV dec-1 and excellent positive and negative bias stabilities have been demonstrated, as well as SiNW-based inverter logics that achieve a gain of 14.6 V/V under a drive voltage of 2.25 V. These results highlight the potential of catalytic SiNWs to serve as advantageous 1D channels for large-area display or transparent electronics.

ZIF-8 nanoparticles densely covered MXene as functionalized platform for electrochemical detection of medical small molecules

The high-performance electrochemical detection relies on sensing material with highly active structure, which requires the development of advanced synthesis technique and the study of its structure-activity mechanism. Herein, the few-layer Ti3C2Tx nanosheets densely coated zeolitic imidazole framework-8 nanoparticles (Ti3C2Tx@ZIF-8) have been successfully prepared as a unique precursor, which combines the structural advantages of two-dimensional Ti3C2Tx and porous ZIF-8 nanoparticles, leading to the vast interior spaces for loading electrocatalytic nanomaterials. For this purpose, Ti3C2Tx@Au nanoparticles-ZnO nanoparticles@N-doped carbon (Ti3C2Tx@AuNPs-ZnO@NC) has been obtained for the simultaneous electrochemical detection of pharmaceutical molecules including dopamine (DA), acetaminophen (AC), and xanthine (XA). The materials characterization and sensing analysis results of Ti3C2Tx@AuNPs-ZnO@NC reveal the structure-activity relationship of Ti3C2Tx, AuNPs and NC resulting in the high-performance behaviors, which can be summed up as stable electrochemical active sites and efficient electron transport channels. First, the abundant anchor points are offered by NC for immobilizing AuNPs, which ensure the electrochemical activity of such material. Second, the close combination of few-layer Ti3C2Tx nanosheets and NC provides an ideal channel for electron transmission along with the electrochemical reaction process. The potential application of Ti3C2Tx@AuNPs-ZnO@NC is displayed to develop the electrochemical medical sensor. The detection limits are 41 nM towards DA, 59 nM towards AC, and 67 nM towards XA. The linear ranges are 3–200 μM for DA, 15–500 μM for AC, and 8–350 μM for XA.

Quantum communications for image transmission over error‐prone channels

AbstractThe introduction of quantum communications, enabled by advancements in quantum computing, is expected to play a significant role in the field of communications. Inherent properties of quantum objects, such as superposition and entanglement, have the potential to provide novel solutions to overcome the challenges encountered by classical communication systems in bandwidth‐intensive applications such as media transmission. This research explores the performance of a quantum communication system in image transmission using quantum superposition and investigates its performance using a simple quantum channel model. With an increase in channel noise, there are significant gains in the rate distortion performance of images transmitted over the quantum channel compared to an ideal classical channel. This novel attempt at constructing a quantum communication‐based image transmission system indicates the potential of the approach to be applied to satisfy the ever‐increasing demands of high‐quality media transmission applications.

Performance improvement of planar silicon nanowire field effect transistors via catalyst atom doping control

Catalytic growth of silicon nanowires (SiNWs), mediated by metallic droplet, provide ideal quasi-1D channels to construct high performance field effect transistor (FET). However, the incorporation of catalytic metal atoms into SiNWs channels has significant impact on the FET characteristics, and thus needs to be better understood and controlled to fulfil its potential for high performance electronics. In this work, we focus on the effect of the incorporation of indium (In) catalytic atoms into planar SiNWs, grown via an in-plane solid-liquid-solid (IPSLS) mechanism, on the FET device performance. It is found that the initial high concentration of p-type In dopants in the as-grown SiNWs led to an equivalent boron (B) doping of 5×1018 cm−3. However, a simple step-wise annealing in oxygen at different temperatures, varied from 620 °C to 920 °C, can help to out-diffuse the dissolved In atoms into the surface SiO2 layer, and reduce the In concentrations down to <5×1017 cm−3, as verified by atom-probe tomography (APT) and four-point-probe measurements. This effective dopant control enables a remarkable device performance improvement of the Schottky barrier FETs, built upon an orderly array of parallel SiNWs of approximately 25 nm in diameter, where the current ratio (Ion/Ioff) has been substantially boosted from 105 to 108, while the subthreshold swing (SS) reduced from 400 mV/dec down to ∼100 mV/dec, with a hole carrier mobility increased from 10 to ∼75 cm2 V−1 s−1 as extracted according to a finite element analysis. These results pave the way for the employment of the catalytic IPSLS SiNWs to serve as high quality 1D channels for high-performance SiNWs-based electronics and sensors.

Governance structure and its links with justice in the context of cooperative organizations

Objective: Cooperative organizations have unique characteristics in their processes and control structures. Given the nature of the relationships that permeate them, justice has stood out as the basis of these relationships, given that the organizations involved seek justice when comparing the rewards and costs involved in interactions. The objective of this essay is to present a theoretical model that makes it possible to explain the links between the governance package (PGov) and the cooperative members' perception of justice and how both reflect on the relational performance of cooperative organizations.Method: This study adopts the theoretical essay method, and assumes the epistemological dimension of structuralism, which generally seeks to explore the structure of the phenomenon and, through its essence, determine its determinant links and interrelationships (Triviños, 1997).Originality/Relevance: Despite advances in understanding the role of control and governance in interorganizational relationships (Ding, Dekker, &amp; Groot, 2013), studies that consider the perspective of justice are still scarce (Dhaundiyal &amp; Coughlan, 2020; Su, Zhang and Guo (2020), and who strive to understand the impacts of these links on performance, which is a differential of the model presented in this essay.Results: This study proposes a model for analyzing the links between the PGov, Organizational Justice and its effects on relational performance. To do so, it was based on the governance and management control structures defended by van der Meer-Kooistra and Scapens (2008), in organizational justice, outlined in its three aspects: distributive justice, procedural justice and interactional justice, addressed by Luo (2007), as well as the notions of relational performance adopted by Su et al. (2020).Theoretical/methodological/practical contributions: The application of the model can bring practical contributions, specifically for the review of the cooperative's PGov and the governance structures to be reformulated (or not), in order to reinforce the justice perceived by the cooperative members. In this way, it is believed that the use of the model will enable the ideal channels of justice to be identified, enhancing the reach of the governance structure and the achievement of the objectives of cooperative organizations.

Theoretical Determination of the Electronic Structures and Energy-Level Splitting for Pr3+-Doped Y2SiO5 Crystals.

Trivalent praseodymium (Pr3+)-doped yttrium silicate (Y2SiO5) crystals have been widely used in various phosphors owing to their excellent luminescence characteristics. Although a series of studies have been carried out on its application prospects, the electronic structures and energy-transfer mechanisms of Pr3+-doped Y2SiO5 (Y2SiO5:Pr) remain an exploratory topic. Herein, the crystal structure analysis by the particle swarm optimization structure search method is used to study the structural evolution of Y2SiO5:Pr. Two novel structures with local [PrO7]-11 and [PrO6]-9 [Y2SiO5:Pr (I) and Y2SiO5:Pr (II)] are successfully identified. The impurity Pr3+ ions occupy the Y3+ sites and successfully integrate into the Y2SiO5 host crystal with a Pr3+ concentration of 6.25%. The calculated electronic band structures show that the doping of Pr3+ induces a reduction in band gaps for the host Y2SiO5 crystal. The conduction bands near the Fermi level are completely composed of f states. For the atomic energies of Pr3+ in Y2SiO5, the Stark levels and transitions are properly simulated based on a new set of crystal field parameters (CFPs) at the C1 site symmetry. A satisfactory r.m.s. dev. of 15.57 cm-1 with 9 free ion parameters (plus 27 fixed CFPs as obtained from ab initio calculation) fitted to the 33 observed levels is obtained for the first time. The plentiful energy-level transition lines, from the visible light to the near-infrared region, are deciphered for Pr3+ in Y2SiO5. Blue 3P0 → 3H4 at 465 nm is calculated to be a strong emission line, and it might be an ideal channel for laser actions. These results could not only provide important insights into the rare-earth-doped crystals but also lay the foundation for future research studies of designing the new laser materials.

EC-MAC: Energy-Aware Cooperative MAC Protocol in Wireless Sensor Network

Nowadays, cooperative communication algorithms have been utilized in Wireless Sensor Network (WSN) to enhance the overall network performance. As is well known, a WSN needs to consider a number of important factors, such as the energy effectiveness and the longevity of the sensor nodes. The energy-aware cooperative medium access control (EC-MAC) protocol is a novel protocol proposed in this paper for usage in WSNs. EC-MAC protocol allows the source nodes to use the intermediate nodes as relays that can be used to transmit the source's data to the access point (AP). This paper demonstrates how the suggested relay selection method can be used by the EC-MAC protocol to choose the best relay node. After channel state information (CSI) has been calculated and acquired, the best relay should have the highest residual energy and the quickest transmission time. Then, by establishing suitable cooperative links, data transmission from a source node to an AP can be carried out. The effectiveness of the EC-MAC protocol in terms of system energy efficiency is examined in this study using the MATLAB simulation tool and compares the outcomes with other cooperative protocols like Modified Cooperative Access MAC Protocol (MCA-MAC) and Throughput and Energy aware Cooperative MAC Protocol (TEC-MAC) and the performance of WSNs employing the suggested EC-MAC protocol is examined in this research for both ideal and dynamic channel conditions. EC-MAC protocol achieved energy efficiency improvements of 20%, and 40% respectively, more than MCA-MAC and TEC-MAC protocols. The results indicated that EC-MAC protocol offers a higher level of energy efficiency for the WSN than other cooperative protocols currently in use.

Negative longitudinal resistance of monolayer graphene in the quantum Hall regime

In the quantum Hall regime, the charge current is carried by ideal one-dimensional edge channels where the backscattering is prohibited by topology. This results in the constant potential along the edge of the Hall bar leading to zero 4-terminal longitudinal resistance rxx. Finite scattering between the counter-propagating edge states, when the topological protection is broken, commonly results in rxx &amp;gt; 0. However, a local disorder, if allowing intersection of the edge states, can result in a counter-intuitive scenario when rxx &amp;lt; 0. In this work, we report the observation and a systematic study of such unconventional negative longitudinal resistance seen in an encapsulated monolayer graphene Hall bar device measured in the quantum Hall regime. We supplement our findings with the numerical calculations, which allow us to outline the conditions necessary for the appearance of negative rxx and to exclude the macroscopic disorder (contamination bubble) as the main origin of it.

SiX2 (X = S, Se) Nanowire Gate-All-Around MOSFETs for Sub-5 nm Applications.

The gate-all-around (GAA) field-effect transistor (FET) holds great potential to support next-generation integrated circuits. Nanowires such as carbon nanotubes (CNTs) are one important category of channel materials in GAA FETs. Based on first-principles investigations, we propose that SiX2 (X = S, Se) nanowires are promising channel materials that can significantly elevate the performance of GAA FETs. The sub-5 nm SiX2 (X = S, Se) nanowire GAA FETs exhibit excellent ballistic transport properties that meet the requirements of the 2013 International Technology Roadmap for Semiconductors (ITRS). Compared to CNTs, they are also advantageous or at least comparable in terms of gate controllability, device dimensions, etc. Importantly, SiSe2 GAA FETs show superb gate controllability due to the ultralow minimum subthreshold swing (SSmin) that breaks "Boltzmann's tyranny". Moreover, the energy-delay product (EDP) of SiX2 GAA FETs is significantly lower than that of the CNT FETs. These features make SiX2 nanowires ideal channel material in the sub-5 nm GAA FET devices.

A New Insight into the Genesis of Graphite Deposits in Madagascar Using U–Pb Zircon Dating and Electron Microprobe Analysis

Madagascar is globally recognized as an important producer of high-quality flaky graphite. However, current research on graphite deposits in Madagascar remains insufficient. Previous studies have linked the genesis of Madagascan graphite deposits to the metamorphism of sedimentary organic matter. Here, we provide a case study of graphite deposits in Madagascar, combining new data from the Ambahita graphite deposit (AMG) in southern Madagascar with data from the Antanisoa graphite deposit (ANG) in central Madagascar and the Vohitasara graphite deposit (VOG) on the east coast of Madagascar. We note that the mineral assemblages of graphite-bearing rocks in the AMG, ANG, and VOG are not typical of metamorphic mineral assemblages but rather the results of filling and metasomatism by mantle-derived fluids that occurred after peak metamorphism. Electron microprobe analysis indicates that the graphite of the AMG, VOG, and ANG is usually associated with phlogopite or Mg-biotite; the phlogopite shares a common genesis with other widespread phlogopite deposits across Madagascar. We reveal that the distribution of graphite deposits in Madagascar is primarily controlled by ductile shear zones between blocks. Ductile shear zones that extend deep into the mantle can provide an ideal migration channel and architecture for the emplacement of mantle-derived fluids. The graphite mineralization formed no earlier than the peak metamorphism (490 Ma) and no later than the intrusion of pegmatite veins (389 ± 5 Ma). The distribution of graphite deposits, graphite orebody morphologies, mineral associations, and geochemical data suggest that the genesis of graphite deposits in Madagascar is linked to mantle-derived fluid filling rather than the metamorphism of sediments, as previously suggested. These findings have important implications for similar deposits in Madagascar and potentially globally.

Intellectual capital information via Twitter: the effect on firm value

PurposeSocial media are emerging as the ideal channel for building one-to-many communication and disseminating intellectual capital (IC) information. Their rise is bringing out new research challenges to investigate the implications of their use. However, there needs to be more research contributions relating to the financial benefits of using social media for IC disclosure (ICD). This study aims to bridge this gap by analyzing, under the lens of signaling theory, the effect of ICD through Twitter on firm value.Design/methodology/approachThis study is based on a content analysis of tweets disseminated by 262 companies aimed at examining the amount of IC information disclosed and on a regression analysis aimed at analyzing the impact of this type of information on firm value.FindingsEmpirical results show that a large ICD via Twitter favors an increase in firm value. They also demonstrate that disclosing information relating to the three IC dimensions positively affects the firm value. These findings suggest that actively and comprehensively communicating IC information via Twitter can help improve the perception and evaluation of the company by investors and other stakeholders.Research limitations/implicationsThis study offers empirical evidence about the financial benefits associated with using social media as disclosure tools by companies. It also enriches the literature on the relationship between ICD and firm value and consolidates the goodness of the signaling theory as an ideal theoretical perspective to frame the relationship between IC information and firm value.Practical implicationsThis study offers important managerial implications for firms and investors. In light of the significant financial benefits, firms should use social media to disclose IC information and should seek to increase their visibility on such platforms to convey the information to a greater number of users. Investors should also heed social media when gathering IC information, combining the analysis of these platforms with that of traditional corporate documents.Originality/valueThis study enriches the limited literature on ICD via social media and extends knowledge about the relationship between IC information and firm value. In this regard, the originality also lies in the individual analysis of the impact of the three IC dimensions on firm value.

Study on the mixing of Ξc and Ξc′ by the transition Ξb→Ξc(′)

Recently, the LHCb Collaboration has observed the decays Ξb0→Ξc+Ds− and Ξb−→Ξc0Ds−. They measured the relative branching fractions times the ratio of beauty-baryon production cross sections R(Ξb0Λb)≡σ(Ξb0)σ(Λb0)×B(Ξb0→Ξc+Ds−)B(Λb0→Λc+Ds−) and R(Ξb−Λb)≡σ(Ξb−)σ(Λb0)×B(Ξb−→Ξc0Ds−)B(Λb0→Λc+Ds−). Once the ratio σ(Ξb0)σ(Λb0) or σ(Ξb−)σ(Λb0) is known, one can determine the relative branching fractions which can be used to exam the mixing of Ξc and Ξc′. In previous literature, Ξc and Ξc′ were assumed to belong to SU(3)F antitriple and sextet, respectively. However, recent experimental measurements, such as the ratio Γ(Ξcc→Ξcπ+)/Γ(Ξcc→Ξc′π+), indicate the spin-flavor structures of Ξc and Ξc′ are a mixture of Ξc3¯ and Ξc6. The exact value of mixing angle θ is still under debate. In theoretical models, the mixing angle was fitted to be about 16.27°±2.30° or 85.54°±2.30° based on decay channels Ξcc→Ξc(′). While in lattice calculation, a small angle (1.2°±0.1°) is preferred. To address such discrepancy and test the mixing of Ξc and Ξc′, here we propose the analysis of semileptonic and nonleptonic decays of Ξb→Ξc and Ξb→Ξc′. We calculate the decay rate of Ξb→Ξc and Ξb→Ξc′ based on the light-front quark model and study the effect of the mixing angle on the ratios of weak decays Ξb→Ξc and Ξb→Ξc′. In particular, we find the transition Ξb→Ξc′ can be an ideal channel to verify the mixing and extract the mixing angle because in theory, the decay rate would be extremely tiny without mixing. Our calculation suggests a measurement of Ξb→Ξc′ can be feasible in the near future, which will help to test flavor mixing angle θ and elucidate the mechanism of decay of heavy baryons. Published by the American Physical Society 2024

A Compact Model for Carbon Nanotube Field Effect Transistors Incorporating Temperature Effects and Application for Operational Amplifier Design

Semiconducting carbon nanotubes (CNTs), characterized by high carrier mobility and atomic thickness, are considered ideal channel materials for building high-performance and ultimate-scale field-effect transistors for future electronics. Here, we present a data-calibrated compact model of CNT field-effect transistors (CNTFETs) that incorporates temperature effects using the virtual source approach. The proposed model also includes the self-heating effect. Temperature effect was characterized by the influence of temperature on devices, achieved through establishing a temperature-dependent semi-empirical model of carrier mobility and carrier velocity. The proposed model can be easily implemented in a simulator. We designed a two-stage operational amplifier (OPAMP) using the proposed model at 32 nm technology. Compared with other studies, the designed CNTFET-based OPAMP demonstrates lower power consumption, which is beneficial for exploring the biological applications of low-power analog circuits in portable electronic devices. Furthermore, the impact of thermal variations on the design of OPAMP, as per the proposed model, was delineated. Investigations revealed that our circuit maintains a high common mode rejection ratio, which diminishes as the temperature increases and exhibits a moderate gain value that escalates with temperature.

Wireless Body Area Nanonetworks via Vascular Molecular Communication.

Advancements in biotechnology and molecular communication have enabled the utilization of nanomachines in Wireless Body Area Networks (WBAN2) for applications such as drug delivery, cancer detection, and emergency rescue services. To study these networks effectively, it is essential to develop an ideal propagation model that includes the channel response between each pair of in-range nanomachines and accounts for the interference received at each receiver node. In this paper, we employ an advection-diffusion equation to obtain a deterministic channel matrix through a vascular WBAN2. Additionally, the closed forms of inter-symbol interference (ISI) and co-channel interference (CCI) are derived for both full duplex (FDX) and half duplex transmission (HDX) modes. By applying these deterministic formulations, we then present the stochastic equivalents of the ideal channel model and interference to provide an innovative communication model by simultaneously incorporating CCI, ISI, and background noise. Finally, we evaluate the results with numerous experiments and use signal-to-interference-plus-noise ratio (SINR) and capacity as metrics.

EEG channel selection using Gramian Angular Fields and spectrograms for energy data visualization

Electroencephalography (EEG)-based brain-computer interfaces (BCIs) have a wide range of applications in affect recognition. The usage of irrelevant information channels when decoding brain activity from different regions can negatively impact the task at hand. Therefore, further research is needed to determine the ideal channels for detecting superior performances. In this study, deep learning models and 2-D image representations are used to assess the efficacy of EEG channels for subjective valence responses to energy data visualizations. The EEG signals are converted into spectrograms and Gramian Angular Field (GAF) images. A hybrid Convolution Neural Network (CNN)-Long-Short Term Memory (LSTM) model and LSTM network are used to extract feature sets from the converted images. These feature sets, after reducing their dimensionality using a principal component analysis (PCA) method, are fed into a boosting classifier (AdaBoost). The performance metrics of both models and 2-D representations are compared. The LSTM and CNN-LSTM models with GAFs and spectrograms achieve state-of-the-art accuracies. The CNN-LSTM model achieves the highest performance when using spectrograms for the F8 channel, while the GAF method performs relatively lower for the F3 channel. The CNN-LSTM model with the spectrogram method produces reliable results, and hence, this method is used for further analysis of the remaining channel pairs. This study suggests that using a single EEG channel is more effective than using multiple channels for recognizing emotions in energy data visualizations. The proposed methodology is an efficient way to select channels for this purpose.

Fidelity Comparation of Two-Qubit Quantum Teleportation with Bit-Flip and Phase-Flip Channel

This study investigates the effect of noise on two-qubit quantum teleportation through a four-qubit entangled channel theoretically. Therefore, in this study a comparison of two states of teleportation through ideal and noisy channel was carried out. The noisy channel can have the effect of bit-flip channel and phase-flip channel. From these two effects, it is found that the channel transforms in-to a mixed state. If the noise is neglected, the channel is pure state. Then, this channel is measured and fidelity is calculated. The fidelity of an ideal environment is 1. This indicates that the teleportation was successfully sent and at the same time confirms the teleportation behavior under ideal conditions. In noisy environments, fidelity can be less than 1. Two factors in noisy environment that affect fidelity are noise factor (p) and the orginal parameter states (transmission coefficients). In this calculation, for the bit flip noise, we observed that as the values of the coefficient values of transmitted state increase, the fidelity value increases. Meanwhile, for the phase flip noise, we observed that as the values of the coefficient values of transmitted state increase, the fidelity value decreases.

How Do Teachers Learn and Engage with Climate Change? An Examination of the &lt;em&gt;Shade Our Schools&amp;mdash;Leaves Are Cool!&lt;/em&gt;&amp;nbsp;Citizen Science Program

Schools are the best venue for increasing climate literacy, and teachers are ideal channels to convey meaningful information to students. However, most teachers have not participated in significant learning experiences or training related to climate change. Informed and well-prepared teachers feel more confident to debate or talk about this subject. Participation in active research provides teachers with a sense of expertise that makes them more confident to teach this topic. By participating in the Shade our Schools—Leaves are Cool! citizen science project developed for the Fairchild Tropical Botanic Garden’s Fairchild Challenge in South Florida, students and teachers conduct a series of experiments to explore how different plant species will fare under climate change scenarios. We surveyed 100+ elementary and middle school teachers during a period of three years to evaluate teacher knowledge gained over the duration of the annual Challenge and the impact of the project in schools. This project has been a successful experience for our participants to learn and engage with climate change–related topics and plant physiology.

Tailoring Parallel Channel Flow Fields for Efficient Mass Transport and Compression in Proton Exchange Membrane Fuel Cells

The adverse effects of global warming have made it critical to transition our reliance on fossil fuels to more sustainable energy sources. Renewable energy can be stored in the form of hydrogen to continuously produce clean energy using a proton exchange membrane (PEM) fuel cell. However, to accelerate commercialization, especially in heavy-duty applications, the performance and durability of the fuel cell needs to be improved. Particularly, PEM fuel cell performance is strongly dependent on the flow fields which should be designed to optimize the transport of reactants and byproducts while maintaining uniform compression of the fuel cell materials. An important flow field design parameter is the channel aspect ratio (channel width by height) which directly influences compression and the transport of reactants and products. Although novel flow field configurations have been studied previously, an investigation on the effects of channel aspect ratio on cell performance using electrochemical testing and operando X-ray imaging has yet to be performed. In this study, we compared the water saturation and electrochemical performance across varying flow field channel aspect ratios from 0.5-2.0 with a fixed active area. The ohmic and mass transport resistances were quantified using electrochemical impedance spectroscopy. Operando X-ray imaging was performed to spatially resolve water saturation under the land and channel regions of the flow fields. We observed that lower channel aspect ratios (or higher number of channels for the given active area) led to lower ohmic resistances but resulted in significant water saturation at higher current densities due to ineffective water removal from the smaller channels. Notably, from these results we elucidated that there exists an ideal channel to rib width ratio to facilitate an effective balance of enhanced water removal using the channels and contact between the porous microstructures under the lands of the flow fields.