Diffusion Potential Research Articles

Voltage and concentration gradients across membraneless interface generated next to hydrogels: relation to glycocalyx.

Next to many hydrophilic surfaces, including those of biological cells and tissues, a layer of water that effectively excludes solutes and particles can be generated. This interfacial water is the subject of research aiming for practical applications such as removal of salts, pathogens or manipulation of biomolecules. However, the exact mechanism of its creation is still elusive because its persistence and extension contradict hydrogen-bond dynamics and electric double layer predictions. The experimentally recorded negative voltage of this interfacial water remains to be properly explained. Even less is known about the nature of such water layers in biological systems. We present experimental evidence for ion and particle exclusion as a result of separation of ionic charges with distinct diffusion rates across a liquid junction at the gel/water interface and the subsequent repulsion of ions of a given sign by a like-charged gel surface. Gels represent features of biological interfaces (in terms of functional groups and porosity) and are subject to biologically relevant chemical triggers. Our results show that gels with -OSO3- and -COO- groups can effectively generate ion- and particle-depleted regions of water reaching over 100 μm and having negative voltage up to -30 mV. Exclusion distance and electric potential depend on the liquid junction potential at the gel/water interface and on the concentration gradient at the depleted region/bulk interface, respectively. The voltage and extension of these ion- and particle-depleted water layers can be effectively modified by CO2 (respiratory gas) or KH2PO4 (cell metabolite). Possible implications pertain to biologically unstirred water layers and a cell's bioenergetics.

Enhancing the performance of a cylindrical nanopore in osmotic power generation through designing the waveform of its inner surface.

Recently, nanofluidic osmotic power, a promising technology converting the salinity difference between brine and fresh water into electricity using nanopores, has drawn the attention of researchers. Previous studies in this field were based mainly on nanopores having a smooth inner surface. To enhance the performance of nanofluidic osmotic power, we investigated four types of cylindrical nanopores, each with a unique waveform wall design (square, saw-tooth, triangle, and sine waves). This study focused on elucidating the influence of bulk salt concentration and geometric characteristics at the solid-liquid interface. We demonstrated that the presence of a waveform wall introduces new variables that have a significant impact on the overall performance of a nanofluidic osmotic power system. At the optimal amplitude of the waveform wall, raising waveform frequency can remarkably improve the osmotic current, diffusion potential, maximum power, and maximum efficiency. The present study provides a novel aspect of osmotic power, where the geometric nature of the nanopore reveals profound and intriguing phenomena primarily attributed to the distribution of ions within its interior.

Improvement of Physical Chemistry Experiment: Measurement of Electromotive Force and Liquid Junction Potential of Primary Batteries

Improvement of Physical Chemistry Experiment: Measurement of Electromotive Force and Liquid Junction Potential of Primary Batteries

Colocalization of cortical diffusivity changes and microglial activation in dementia

AbstractBackgroundThere is growing evidence that microglial activation plays a crucial role in the early pathological changes reported in Alzheimer’s disease (AD). Multimodal neuroimaging can be used to detect micro‐ and macrostructural alterations together with molecular imaging to quantify metabolism and proteins expression. Diffusivity map, reflecting neuronal integrity, can be derived from diffusion‐weighted imaging, and is thought to be increased in AD following pathological alterations. We hypothesised that changes in diffusivity could be colocalized with microglial activation at different stages of the disease.Method56 patients (mean age=70.4, SD=8.5) cognitively normal (CN, n=15), with mild cognitive impairment (MCI, n=28) and with AD (n=12) were included in this study. All participants underwent diffusion tensor imaging (DTI), amyloid PET ([18F]flutemetamol) and TSPO PET ([11C]PBR28). DTI data were processed with FSL v.6.0 to compute mean diffusivity (MD) maps. Standard uptake ratio (SUVR) values were calculated in SPM12 to identify the amyloid deposition and microglial activation within cortical regions. Amyloid status (Aβ‐positive/Aβ‐negative) was determined from processed data using a cerebellar gray matter ratio with a binding value greater than the CN mean+2SD. Z score maps of MD and [11C]PBR28 SUVR were computed using CN amyloid negative participants as reference. Z score maps were then correlated using SPM8 and the BPM toolbox. Significance was set at a threshold of p<0.05 with an extended threshold of 50 voxels.ResultWe found a significant positive correlation clusters between MD and PBR28‐SUVR Z score maps (higher diffusivity correlated with higher microglial activation) in MCI amyloid negative subjects in the temporal lobe (coordinates: 28 ‐3 ‐32, corrected p<0.001, k=7363). In MCI amyloid positive subjects, we found positive correlation in the parietal lobe (coordinates: ‐47 ‐41 39, corrected p=0.008, k=5712).ConclusionWe found colocalized diffusivity and microglial changes in the early stage of the disease, in the temporal lobe of MCI amyloid negative participants and in later stages of the disease, in the parietal lobe of MCI amyloid positive participants. These results suggest the potential of DTI diffusivity and microglial activation imaging in detecting early neuronal damage occurring in dementia.

Reverse entrepreneurship and integration in poor areas of China: Case studies of tourism entrepreneurship in Ganzi Tibetan Region of Sichuan

In the context of urbanisation and the decline of the countryside, reverse entrepreneurship cannot be separated from integration, referring to a process of mutual trust and cooperation between reverse (returnee or immigrant from urban areas) entrepreneur, host community and external stakeholders for sustainable livelihoods. With a geographic focus on poor areas of China, this paper aims to reveal key factors behind successful initiatives of reverse entrepreneurship to address challenges facing local communities, and pathways for mobilising and effectively using various resources, both internally and externally. These objectives are addressed through multiple cases of tourism development in Ganzi, a Tibetan Minority Prefecture of Sichuan. This paper contributes to the literature on entrepreneurial integration to debates on reverse entrepreneurship in three aspects. Firstly, entrepreneurial integration starts from social embeddedness, interconnecting and interacting between reverse entrepreneur(s) and the host community to understand local challenges and share a new vision for sustainable livelihoods. Secondly, entrepreneurial integration is essentially an innovation platform to develop or enhance social capital (both bonding and bridging) for mobilising and effective use of critical resources. Finally, the study outlines five pathways of tourism entrepreneurship, which reflects variations in livelihood strategy, critical capitals, business models, innovation diffusion and application potential.

Modified and Optimized Glass Electrode for pH Measurements in Hydrated Ethanol Fuel.

One of the quality control parameters of ethanol fuel is pH, established by the Brazilian standard ABNT NBR 10891, whose scope is specific for hydrated ethanol fuel, and by the American standard ASTM D 6423, which focuses on anhydrous ethanol fuel. This study presented a modified and optimized structure using a single solvent, both for the glass electrode and the external reference electrode, to minimize the presence of the liquid junction potential for measuring the pH of hydrated ethanol fuel. The Box-Behnken design enabled us to determine the optimal condition expected for the new measurement system, which was compared with the systems proposed by the standard references and the turning range of acid-base indicators using parametric and nonparametric tests. The results revealed that the pH values obtained by the different systems are statistically different, and that only the values obtained by this proposal are suitable for the pH range found by the indicators. The optimized electrode presented an adequate response sensitivity to the Nernst equation, having an operational behavior adequate for the modified and optimized glass electrode for pH measurements in hydrated ethanol fuel.

Shape-aware stochastic neighbor embedding for robust data visualisations

BackgroundThe t-distributed Stochastic Neighbor Embedding (t-SNE) algorithm has emerged as one of the leading methods for visualising high-dimensional (HD) data in a wide variety of fields, especially for revealing cluster structure in HD single-cell transcriptomics data. However, t-SNE often fails to correctly represent hierarchical relationships between clusters and creates spurious patterns in the embedding. In this work we generalised t-SNE using shape-aware graph distances to mitigate some of the limitations of the t-SNE. Although many methods have been recently proposed to circumvent the shortcomings of t-SNE, notably Uniform manifold approximation (UMAP) and Potential of heat diffusion for affinity-based transition embedding (PHATE), we see a clear advantage of the proposed graph-based method.ResultsThe superior performance of the proposed method is first demonstrated on simulated data, where a significant improvement compared to t-SNE, UMAP and PHATE, based on quantitative validation indices, is observed when visualising imbalanced, nonlinear, continuous and hierarchically structured data. Thereafter the ability of the proposed method compared to the competing methods to create faithfully low-dimensional embeddings is shown on two real-world data sets, the single-cell transcriptomics data and the MNIST image data. In addition, the only hyper-parameter of the method can be automatically chosen in a data-driven way, which is consistently optimal across all test cases in this study.ConclusionsIn this work we show that the proposed shape-aware stochastic neighbor embedding method creates low-dimensional visualisations that robustly and accurately reveal key structures of high-dimensional data.

Adsorption and Diffusion Behaviors of CO2 and CH4 Mixtures in Different Types of Kerogens and Their Roles in Enhanced Energy Recovery

CO2 geological sequestration in subsurface shale formations is a promising strategy to store CO2 and to increase shale gas production. The understanding of gas adsorption and diffusion mechanisms in microporous media is critical for CO2 storage-enhanced gas recovery (CS-EGR). The type of kerogens is one of the important factors that influence the adsorption and diffusion behaviors of gases. In this work, the Grand Canonical Monte Carlo and Molecular Dynamics simulations were utilized to develop kerogen models and further investigate gas and water adsorption and diffusion behavior on the type IA, IIA, and IIIA kerogen models. The results indicated that the adsorption and diffusion capacities of CO2 are larger than those of CH4. The adsorption and diffusion capacity decreased with increasing water content. However, the CO2/CH4 adsorption selectivity increased with the increase in water content. Type IIIA demonstrated the best potential for adsorption and diffusion. This study provides insights into the role of the adsorption and diffusion behavior of CO2 and CH4 mixtures on kerogens of different types under different water contents at a microscopic scale, and can facilitate further understanding of the processes involved in CO2 storage coupled with enhanced energy recovery.

QPHT graphene as a high-performance lithium ion battery anode materials with low diffusion barrier and high capacity

In past two decades, scientists have worked to find battery anode materials with high lithium storage capacity and good electrical conductivity to better solve the problems of environmental protection, cleanliness and sustainable energy. In this manuscript, we choose a novel two-dimensional carbon material that can exist stably at room temperature — QPHT graphene, as the research object. By employing first-principles calculations, we investigated the diffusion barrier and open circuit voltage of QPHT graphene. Similar to graphene, QPHT graphene has a relatively low lithium diffusion potential barrier (<0.83 eV), high lithium storage capacity (837 mAh/g) and average open circuit voltage (0.66 V), making it an auspicious anode material for fast charge/discharge lithium ion battery. The present study is essential for exploring the application of novel graphene in lithium ion battery anode materials.

A cross-cultural study of nonprofit self-organized ridesharing.

Nonprofit ridesharing presents an underutilized opportunity for increasing transportation sustainability, as well as users' economic and social benefits, while reducing adverse environmental impacts. However, while app-based ridesharing has achieved only modest uptake, mostly limited to longer trips, in certain contexts, self-organized ridesharing (SORS) has shown significant achievements, even for the challenging short- and mid-range commuting trips. Still, knowledge regarding the key elements and mechanisms behind successful SORS is partial, hindering the ability to effectively leverage SORS diffusion and scaling potential. Following the premise that successful initiatives may provide learning opportunities, this study aims at narrowing this knowledge gap by performing a comparative cross-cultural systematic study of eight diverse SORS cases. The study uses a recently designed conceptual framework and multiple research methods (mainly online data exploration, personal interviews, observations, and documents analysis) to comprehensively examine SORSs' attributes and evolution stages and processes. Study findings highlight repeated patterns as well as the role of context, official actors, and local practices in shaping initiative's dynamics towards success. The study offers general and specific policy recommendations for supporting the early development, growth, and diffusion of SORS, as well as reflections on post pandemic ridesharing.

Unlocking the human inner ear for therapeutic intervention

The human inner ear contains minute three-dimensional neurosensory structures that are deeply embedded within the skull base, rendering them relatively inaccessible to regenerative therapies for hearing loss. Here we provide a detailed characterisation of the functional architecture of the space that hosts the cell bodies of the auditory nerve to make them safely accessible for the first time for therapeutic intervention. We used synchrotron phase-contrast imaging which offers the required microscopic soft-tissue contrast definition while simultaneously displaying precise bony anatomic detail. Using volume-rendering software we constructed highly accurate 3-dimensional representations of the inner ear. The cell bodies are arranged in a bony helical canal that spirals from the base of the cochlea to its apex; the canal volume is 1.6 μL but with a diffusion potential of 15 μL. Modelling data from 10 temporal bones enabled definition of a safe trajectory for therapeutic access while preserving the cochlea’s internal architecture. We validated the approach through surgical simulation, anatomical dissection and micro-radiographic analysis. These findings will facilitate future clinical trials of novel therapeutic interventions to restore hearing.

Electrode Potentials Part 1: Fundamentals and Aqueous Systems

Electrochemistry deals with the interrelationship between electrical and chemical energy. Various potentials appear in electrochemistry and pertain to one another in practical cells. Understanding the electrode potential is an important step in acquiring basic knowledge of electrochemistry and extending it to specific applications. This comprehensive paper outlines the fundamentals and related subjects of electrode potentials, including electrochemical cells and liquid junction potentials. Aqueous solution systems are ideal for connecting the theoretical background of electrode potentials to practical electrochemical measurements. Accordingly, the basic electrode chemistry in aqueous systems is described in this paper, as well as several advanced concepts introduced in recent studies.

Some Electrical and Photoelectrical Properties of Conducting Polymer Graphene Composite /n-Silicon Heterojunction Diode

In this study, polythiophene-graphene (PTh-G) composite thin film was prepared on the n-type silicon (n-Si) semiconductor wafer by the spin coating method. Subsequently, the current-voltage (I-V) measurements were made on the fabricated Au/PTh-G/n-Si/Al device to ascertain the impact of the PTh-G interfacial layer on the device performance. The main device parameters such as ideality factor (n), barrier height (b), series resistance (Rs) were calculated by using the thermionic emission (TE) and Norde functions, and then, the obtained results were discussed in detail. Additionally, the capacitance-voltage (C-V) characteristic of the device was examined as a function of the frequency, and the device parameters such as diffusion potential (Vd), Fermi energy level (Ef), carrier concentration (Nd), b were detemined. Finally, the light intensity-dependent I-V measurements were taken to obtain information about the photoelectrical characteristics of the fabricated device. The obtained results have shown that the prepared composite material has a good potential to be used in optoelectronic applications such as photodiode, and photodetector.

Post-deposition annealing effect on the structural and electrical properties of ytterbium oxide as an alternative gate dielectric

The possibility of ytterbium(III) oxide, one of the rare earth oxides, to replace silicon dioxide used as the gate dielectric is discussed in this article. For such a replacement, it is primarily necessary to understand the physical and chemical characteristics of ytterbium(II) oxide as a candidate, such as bond structure, electronic structure, band offsets with Si, dielectric constant, interfacial states and defect behavior. The effects of structural and electrical features of ytterbium(III) oxide-based MOS capacitors on device performance are investigated. The electron beam physical vapor deposition (EBPVD) technique was used for the deposition of ytterbium(III) oxide thin films. The 122 nm thick Yb2O3 thin film was annealed at four different temperatures (200 °C, 400 °C, 600 °C, and 800 °C) in nitrogen environment. The crystallite size determined from the as-deposited sample as 15 nm is the lowest. As expected, crystallite sizes increased as a result of increasing annealing temperature. The presence of Yb2+ oxidation states increased in the region close to the interface or at the interface. The binding energies of the Yb 4d and O 1s spectra increased with increasing depth into the films. In the O 1s spectra, the organic bonds on the surface first decreased and then increased with increasing annealing temperature. Silicate formation at the interface was determined for the annealed samples. This affected the electrical performance of the capacitors. The calculated dielectric values range from 12.1 to 15.8. Interface level densities were found in the order of 1012 cm−2 and it did not exhibit frequency-dependent behavior. The calculated values for the effective charge densities varied between −24.19 × 1011–7.03 × 1011 cm−2. It has been determined that mostly negative charges are trapped more for different capacitors. Finally, Fermi energy level, dopant concentration, diffusion potential and barrier heights were calculated.

One-Step Hydrothermal Reaction Induced Nitrogen-Doped MoS2/MXene Composites with Superior Lithium-Ion Storage

MoS2, a typical transition metal dichalcogenide (TMDs), inheriting high theoretical capacity, open framework and unique electrochemical properties, is regarded as a promising electrode material. However, the low electronic conductivity and slow chemical kinetics of two-dimensional (2D) MoS2 lamellars, along with the large volume expansion during cycling hinder their application in Li-ion batteries. MXene inherits the strengths of excellent metallic conductivity, a low lithium-ion diffusion potential barrier and superior mechanical stability; however, its low reversible capacity and self-stacking problems as anode still need to be solved. Herein, the MXene Ti3C2Tx compound with MoS2 through a simple one-step hydrothermal reaction is introduced. The introduction of nitrogen-doped Ti3C2Tx can effectively restrain the volume change of MoS2 and ameliorate the electronic conductivity of the whole electrode, while MoS2 can alleviate the self-stacking of Ti3C2Tx during cycling. The as-prepared MoS2/MXene electrode delivers an initial discharge capacity of 1087 mA h g−1 with an initial Coulombic efficiency (ICE) of 81.6% at 100 mA g−1, and a specific discharge capacity of 731 mA h g−1 can be retained after 100 cycles. The excellent electrochemical performance demonstrates that nitrogen-doped MoS2/MXene can be a potential electrode material for Li-ion batteries.

The examination of the electrical properties of Al/Mg2Si/p-Si Schottky diodes with an ecofriendly interfacial layer depending on temperature and frequency

The electrical properties of Al/Mg2Si/p-Si Schottky diodes fabricated were examined at various frequencies and temperatures. The structural and surface morphological features of the interface layer (Mg2Si) were analyzed by XRD, SEM, and EDX. For the fabricated diode, temperature-dependent measurements were made in the range of 120–340 K with an increment of 20 K. The frequency-dependent measurements were also performed in the range of 1 kHz–5 MHz. For the Al/Mg2Si/p-Si Schottky diode, the temperature-dependence of ideality factor (n), saturation current (I0), zero-bias barrier height (ΦB0), serial resistance (Rs) and interface state density (Nss) were investigated. Besides, diffusion potential (VD), Fermi energy (EF), concentration of acceptor atoms (NA), the depletion layer width (WD) and frequency dependent obstacle height (ΦB0C–V) values were calculated from frequency dependent measurements. It was found that the Al/Mg2Si/p-Si Schottky diode is suitable for use in electronic applications in a wide temperature and frequency range.

Formation and evolution of hierarchical microstructures in a Ni-based superalloy investigated by in situ high-temperature synchrotron X-ray diffraction

Hierarchical microstructures are created when additional γ particles form in γ’ precipitates and they are linked to improved strength and creep properties in high-temperature alloys. Here, we follow the formation and evolution of a hierarchical microstructure in Ni86.1Al8.5Ti5.4 by in situ synchrotron X-ray diffraction at 1023 K up to 48 h to derive the lattice parameters of the γ matrix, γ’ precipitates and γ particles and misfits between phases. Finite element method-based computer simulations of hierarchical microstructures allow obtaining each phase's lattice parameter, thereby aiding peak identification in the in situ X-ray diffraction data. The simulations further give insight into the heterogeneous strain distribution between γ’ precipitates and γ particles, which gives rise to an anisotropic diffusion potential that drives the directional growth of γ particles. We rationalize a schematic model for the growth of γ particles, based on the Gibbs-Thomson effect of capillary and strain-induced anisotropic diffusion potentials. Our results highlight the importance of elastic properties, elastic anisotropy, lattice parameters, and diffusion potentials in controlling the behavior and stability of hierarchical microstructures.

Photo-electrical Characterization of New CuAlNi/n-Si/Al Schottky Photodiode Fabricated by Coating Thin-Film Smart Material

Micro/nano scale thin-film shape memory alloys (SMAs) have been used in many different miniaturized systems. Using them as thin-film metal components in fabrication of Schottky photodiodes has started a few years ago. In this work, a new SMA-photodiode device with CuAlNi/n-Si/Al structure was produced by coating nano-thick CuAlNi SMA film onto n-Si wafer substrate via thermal evaporation. The photoelectrical I-V, C-V and I-t photodiode signalization tests were performed under dark and varied artifical light power intensities in room conditions. It was observed that the new device exhibited photoconductive, photovoltaic and capacitive behaviors. By using conventional I-V method, the diode parameters such as electrical ideality factor (n), Schottky barrier height (ϕb) and rectification ratio (RR) of the produced photodevice for the condition of dark environment were computed as 12.5, 0.599 eV and 1266, respectively. As good figure of merits, the photodiode’s performance parameters of responsivity (Rph), photosensivity (%PS) and spesific detectivity (D*) maxima values determined for at -5 V reverse voltage bias and under 100 mW/cm2 of light power intensity condition are as 0.030 A/W (or 30 mA/W), 18693 and 1.33×1010 Jones, respectively. The current conduction mechanism analysis revealed that the space charge limited conduction (SCLC) mechanism is the dominant current conduction mechanism. By the drawn reverse squared C-2-V plots, the values of diffusion potential (Vd), donor concentration (ND), Fermi level (EF) and also barrier height (ϕb) were determined for the SMA-photodiode. The results indicated that the new SMA-photodiode device can be useful in optoelectronic communication systems and photosensing applications.

The Circular Decision-Making Tree: an Operational Framework

Because of the need to limit extraction of raw materials and reduce amounts and impacts of waste, countries and businesses are challenged to transition to a circular economy: an economic system in which the materials are reduced, reused, or recycled, but not wasted. Yet, transitioning from a linear to a circular economy implies societal-level, structural changes that have deep implications for existing business models and practices–and the current economic system is still largely organized around virgin material extraction and linear modes of production and consumption. Despite stated ambitions at various geographical scales to become more or fully circular, the outcomes still fall short of such visions. One important reason why the transition towards a circular economy is not proceeding as quickly as hoped can be found in the decision processes used by companies, investors, and policy makers. Suitable frameworks that support decision-making could thus be a key enabler of this transition, if based upon a circular and transformative, rather than a linear optimization logic. In this paper, we therefore explore a different decision-making logic that is developed based on circularity. This provides the basis for an operational framework designed to help decision-makers such as policymakers, investors, and entrepreneurs navigate tradeoffs and take decisions considering the quality of innovation circularity and its respective diffusion potential. To develop, test, and refine our framework—the “Circular Decision-Making Tree”—we synthesized insights from existing frameworks and conceptually integrated these with our understanding of transition theory and the circular economy. We then verified the internal logics and applicability of the framework in a series of usability workshops across four application contexts (Netherlands, Brazil, UK, and South Africa) with feedback from a total of n = 50 stakeholders from policy, practice, and academia. We critically discuss the application potential as well as the limitations and describe implications for future research to further validate the framework’s logics and operationalization.

Expanding Warning: Anticipating Diffused Threats

The strategic warning function can be understood in two ways. One emphasizes existing and anticipated threats and threat streams, known challengers, and discrete events. This understanding of warning asks, for example, about the who, what, where, when, and how of the next attack. It is dependent on clearly defined spatial and temporal parameters. Another understanding of warning emphasizes the unknown, the more diffuse threat potential. More anticipatory in nature, this function of warning looks beyond the expected and the usual to ask about possible events not yet recognizable from available intelligence or relatable from previous experience. The first understanding of warning, as it is generally practiced, offers either predictions or forecasts of potential future developments, couched in terms of definitive statements or probabilistic assessments. The second, presented in this article, foregoes both prediction and forecasting, suggesting instead that warning can be expanded and augmented by adopting a foresight approach that emphasizes option identification. Intended to supplement existing warning activities, foresight-based warning activities would leverage unbounded scenarios and iterative probability assessments to enhance and expand warning through greater consideration and attentiveness to emergent, unique, unexpected, and diffused threats.