Typical Conversion Research Articles

Corrosion of Surface-Treated Type 304 Stainless Steel in Alkaline Subcritical Water

Surface treatment can reduce corrosion of stainless steel in hot-pressurized (subcritical/supercritical) water and, thus is being considered to control corrosion of austenitic stainless steel Type 304 (Fe-18Cr-8Ni) for application to hydrothermal liquefaction (HTL) conversion of biomass. Typical HTL conversion processes involve hot (250°C to 374°C), pressurized (4 MPa to 22 MPa) subcritical water as the conversion medium with the addition of a homogenous alkaline catalyst. The objective of this research was to determine the relative extent to which well-established surface treatments could reduce corrosion of Type 304 in simulated HTL alkaline water, with the chromia-forming Alloy 33 (Fe-33Cr-32Ni) serving as a comparative baseline. Surface treatments examined include grinding, shot peening, sandblasting, and chemical pickling. Corrosion was assessed using gravimetric measurements made after 10 d of immersion in simulated HTL alkaline water at 310°C and 10 MPa in a static autoclave test system. Analysis of the starting (preimmersion) and corroded (postimmersion) surfaces was conducted using a variety of surface characterization techniques. None of the surface treatments reduced corrosion of Type 304, relative to the mechanically-ground surface, despite achieving the desired outcomes before and during immersion. Alloy 33 is less susceptible to corrosion than Type 304 due to the formation of a more protective Cr2O3 sublayer at the oxide/metal interface.

A robust floating oxygen-doped graphitic carbon nitride sheet for efficient photocatalytic CO2 conversion

Photocatalytic CO2 reduction offers a promising approach for converting CO2 into valuable chemicals. However, typical conversion systems suffer from inefficient CO2 mass transfer and complex recycling processes. In this study, we developed a floating sheet as a robust photocatalytic CO2 conversion system by integrating graphitic carbon nitride (CN) nanosheets onto polytetrafluoroethylene (PTFE) fiber membrane, followed by oxygen (O) doping into the CN (CN-O) via oxygen-plasma treatment. The floatable CN-O/PTFE sheet exhibits slight wettability in water under 0.25 MPa of CO2 pressure in our reactor system, facilitating the delivery of dissolved CO2 to the CN-O photocatalyst surface. O-doping enhances the visible light absorption and improves the separation and transport efficiency of photogenerated electrons and holes due to O-doping-induced states in CN. Consequently, the floating CN-O/PTFE system achieves an exceptional photocatalytic CO2 conversion rate of 102.3 μmol g-1h-1, approximately 4.8 times higher than a conventional CN-powder dispersion system in water. Moreover, the sheet demonstrates excellent cycling durability, with no significant exfoliation of the catalytic layer or reduction in CO2 photoreduction activity after 20 consecutive cycles. This study presents a novel approach to designing photocatalytic systems for efficient CO2 conversion.

Recent Progress in Situ Application of H2O2 Produced via Catalytic Synthesis.

Industrial production of H2O2 requires lots of energy and causes environmental pollution. Moreover, in subsequent applications, much economic loss could be produced during the transportation process of H2O2 and its dilution process. Therefore, it is highly desirable for in situ application of H2O2. In recent years, catalytic synthesis of H2O2, e. g., direct catalytic synthesis, electrocatalytic synthesis, and photocatalytic synthesis, has attracted more and more attention because the continuous and low-concentration H2O2 produced by catalytic synthesis can be directly used for the oxidation of organic compounds, effectively avoiding the shortcomings of the current industrial route. Here, we briefly reviewed the latest processes for the catalytic production of H2O2 via various routes. On this basis, we summarized and discussed the in situ application of H2O2 in typical organic conversion reactions, including the ammoximation of ketones, the oxidation of alcohols, the oxidation of C-H bonds, and the oxidation of olefins. Some in situ coupling reactions have shown excellent performance with high conversion and selectivity, and the economic cost has been significantly reduced. Finally, the shortcomings of the in situ utilization of H2O2 in coupling reactions were analyzed, and some strategies for promoting the efficiency of the H2O2 application in organic synthesis were proposed.

Statistical Study of Energy Transport and Conversion in Electron Diffusion Regions at Earth's Dayside Magnetopause

AbstractThe electron diffusion region (EDR) is a key region for magnetic reconnection, but the typical energy transport and conversion in EDRs is still not well understood. In this work, we perform a statistical study of 80 previously published near X‐line events identified at the dayside magnetopause in Magnetospheric Multiscale data. We find 44 events that clearly present all commonly accepted EDR signatures and use this database to investigate energy flux partition and energy conversion. We find that energy partition is changed inside EDRs, with a 71%–29% allocation of particle energy flux density between electrons and ions respectively. The electron enthalpy flux density is found to dominate locally at all EDRs and is predominantly oriented in the out‐of‐plane direction, perpendicular to the reconnecting magnetic field. We also examine the transition from electron‐ to ion‐dominated energy flux partition further from the EDR, finding this typically occurs at scales of the order of the ion inertial length, larger than the typical EDR size. We then investigate energy conversion and transport and highlight complex processes, with potential non‐steady‐state energy accumulation and release near the EDR. We discuss the implications of our results for reconnection energy conversion, and for magnetopause dynamics in general.

PHATIC COMMUNICATION IN ONLINE ENGLISH CLASS DISCUSSIONS THROUGH FACEBOOK COMMENTS

Phatic communication refers to small talks that aim to form ties of personal union between people or the speakers. Especially in this digital age, phatic communication is somehow still used. This research aims to uncover the kinds and functions of phatic communication used by Indonesian students who have been doing online classes through Facebook, responding to their classmates‘ material presentations, and having discussions in the comment column. This current study employs the qualitative method with the document analysis technique. The data of this recent study is the phatic communication used by students during the online course through Facebook, and the data was examined through document analysis techniques from the students‘ Facebook comments activity in the form of words, phrases, clauses, and sentences related to phatic expressions. Moreover, the data was analyzed through the following steps: 1) labeling the related data; 2) classifying the data into its types and functions; 3) interpreting the data findings; and 4) drawing conclusions.The study‘s main finding is the appearance of phatic expressions, for instance, greeting, thankfulness,compliment, apology, encouragement, and wishing to each other. As the typical conversation is made online through social media platforms such as Facebook, we suggest that some language or conversation styles like abbreviations, non-standard spelling, and emojis have also appeared.

Design and development of efficient and compact 20 kW 325MHz solid-state amplifier for superconducting accelerator applications.

An efficient and compact, 20 kW solid-state power amplifier (SSA) at 325MHz has been designed and developed in-house, using single stage combining. It comprises of 24 nos. of 1 kW power amplifier (PA) modules, a 24-way Wilkinson power combiner and divider, and other peripheral systems. The typical gain and conversion efficiency of the PA modules at 1.0 kW output is 21.7 dB and 66.6%, respectively. It is demonstrated that overall power gain and AC to RF efficiency of this SSA at 20 kW is 88.5 dB and 54.8%, respectively, which matches closely with the design estimates. The harmonic content in the RF output is < -40 dBc for all the harmonics. The results of the Monte Carlo simulation are also presented, showing lower bound on combining efficiency with a degree of confidence if magnitude and phase data for 24 inputs are randomly chosen from a normal distribution's pre-defined interval. The salient features of this SSA include power density of 12.7 kW/m3, AC to RF efficiency of 54.8% at 20 kW, and guaranteed output of 20 kW with one failed PA module and 18.1 kW under two failed PA modules condition.

Comparison of Outcomes Between Robot-Assisted Language Learning System and Human Tutors: Focusing on Speaking Ability

This study explores how much current mainstream Robot-Assisted Language Learning (RALL) systems produce outcomes compared to human tutors instructing a typical English conversation lesson. To this end, an experiment was conducted with 26 participants divided in RALL (14 participants) and human tutor (12 participants) groups. All participants took a pre-test on the first day, followed by 30 min of study per day for 7 days, and 3 post-tests on the last day. The test results indicated that the RALL group considerably improved lexical/grammatical error rates and fluency of speech compared to that for the human tutor group. The other characteristics, such as rhythm, pronunciation, complexity, and task achievement of speech did not indicate any differences between the groups. The results suggested that exercises with the RALL system enabled participants to commit the learned expressions to memory, whereas those with human tutors emphasized on communication with the participants. This study demonstrated the benefits of using RALL systems that can work well in lessons that human tutors find hard to teach.

Boosting Manganese Selenide Anode for Superior Sodium-Ion Storage via Triggering α → β Phase Transition.

Sodium-ion batteries (SIBs) have been extensively studied owing to the abundance and low-price of Na resources. However, the infeasibility of graphite and silicon electrodes in sodium-ion storage makes it urgent to develop high-performance anode materials. Herein, α-MnSe nanorods derived from δ-MnO2 (δ-α-MnSe) are constructed as anodes for SIBs. It is verified that α-MnSe will be transferred into β-MnSe after the initial Na-ion insertion/extraction, and δ-α-MnSe undergoes typical conversion mechanism using a Mn-ion for charge compensation in the subsequent charge-discharge process. First-principles calculations support that Na-ion migration in defect-free α-MnSe can drive the lattice distortion to phase transition (alpha → beta) in thermodynamics and dynamics. The formed β-MnSe with robust lattice structure and small Na-ion diffusion barrier boosts great structure stability and electrochemical kinetics. Hence, the δ-α-MnSe electrode contributes excellent rate capability and superior cyclic stability with long lifespan over 1000 cycles and low decay rate of 0.0267% per cycle. Na-ion full batteries with a high energy density of 281.2 Wh·kg-1 and outstanding cyclability demonstrate the applicability of δ-α-MnSe anode.

A 1.2v ΔΣ ADC Modulator Using 4-bit SAR Quantizer for Biomedical Applications by using 65nm CMOS Technology

This research focuses on enhancing Sigma-Delta ADC modulators for biomedical applications by leveraging the working principle of Successive Approximation ADC circuits. The proposed modulator includes a comparator, DAC, successive approximation register, and control circuit. The operational process begins with the sample and holds circuit-initiating conversions by sampling the input signal, and then compared with the DAC output. Using a 4-bit example, the successive approximation register refines the DAC output through iterative bit adjustments until the closest digital code approximation to the input is voltage independent of input voltage, occurring incrementally one bit at a time. The proposed enhancement aims to optimize Sigma-Delta ADC modulator performance for biomedical applications, ensuring high resolution and speed. Typical conversion speeds range from 2 to 5 MSPS, with resolutions varying from 8 to 16 bits, contributing to improved precision and efficiency in capturing and digitizing biomedical signals.

Обращение И.Г. Гамана как ключ к его творчеству

The article deals with the mechanism of the religious conversion of the 18th century Königsberg writer J.G. Hamann as well as the infl uence of this event on his subsequent literary activity characterized by an insightful critique of the Enlightenment project. In his autobiography not geared toward the public, this conversion has features of a typical Pietist conversion with its peculiar language as well as normative accents on feelings along with the lowered role of reason. His debut work “Socratic Memorabilia”, however, which was addressed to I. Kant and I.K. Berens, served as vindication of his new “Weltanschauung”, and enables one to interpret his conversion as a transition to a new conceptual scheme with its own distinct interpretation of texts, ideas, and events. Theological-philosophical foundations of Hamann’s conversion have greater signifi cance than its psychological aspects. Within this framework, the former life is then viewed from a different perspective. However, it is the text and the author behind the text (rather than internal feeling of the heart) that is primary to Hamann. This text presupposes subsequent authorship of Hamann himself. Thus, the London conversion experience of Hamann may not be reduced to ecstasy, elimination of cognitive and rational capacities, but rather viewed as “metanoia”, a change of thinking, way of life, and worldview. From this perspective it is more appropriate to view the ensuing philosophical career of Hamann as activity in a different framework rather than conceptualization of personal experience of conversion. While his efforts were directed at a variety of subjects (theology and philosophy of history, aesthetics, philosophy of language, correlation of faith and reason, critique of political basis of the Enlightenment), the very thrust of his thinking was governed by a conceptual scheme, which in turn also implied a different lifestyle (attitude to professional activity, family, and marriage), incongruent with the conventional notions of the time.

Star Formation and AGN Activity 500 Myr after the Big Bang: Insights from JWST

We consider the effect of including an active galactic nuclei (AGN) component when fitting spectral energy distributions of 109 spectroscopically confirmed z ≈ 3.5–12.5 galaxies with JWST. Remarkably, we find that the resulting cosmic star formation history is ≈0.4 dex lower at z ≳ 9.5 when an AGN component is included in the fitting. This alleviates previously reported excess star formation at z ≳ 9.5 compared to models based on typical baryon conversion efficiencies inside dark matter halos. We find that the individual stellar masses and star formation rates can be as much as ≈4 dex lower when fitting with an AGN component. These results highlight the importance of considering both stellar mass assembly and supermassive black hole growth when interpreting the light distributions of among the first galaxies to ever exist.

Energy, economic, and environmental analysis of converging air-based photovoltaic-thermal (air/PV-T) systems: A yearly benchmarking

Two converging channel configurations of photovoltaic-thermal (PV-T) systems, i.e., inlet and outlet at different sides (Case 1) and the inlet at the middle and outlets at the sides (Case 2), are investigated numerically. The results reveal that Case 1 features a nearly uniform and lower temperature distribution (up to 7 °C) for practical air flows, and the appropriate convergence ratio is 2:1 (inlet to outlet channel height) for which the PV surface temperature is lower by 8 °C than that of a similar conventional collector. Meanwhile, energy analyses based on the so called ‘rate of extra energy gain per PV surface area, E˙Ac (W/m2)’ show that the air mass-flow rate has an optimal limit of ∼0.1 kg/m2. s for a typical conventional power plant conversion factor (PPCf) of 0.3–0.4. At this limit, up to 500 W extra power per unit area of PV module can be gained by changing a PV to its proposed counterpart PV-T system reducing the levelized cost of energy (LCOE) by an order of magnitude for the PV-T (0.02–0.054 $/kWh) compared to a standalone PV (0.037–0.146 $/kWh). Such PV-Ts show 10% and 150% net CO2 mitigation in comparison to the conventional PV-Ts and the corresponding standalone PVs.

Analyzing characteristics of collateral flow to parasylvian cortical arteries by three-dimensional digital subtraction angiography-magnetic resonance angiography fusion imaging in adult moyamoya disease.

The hemodynamic sources of recipient parasylvian cortical arteries (PSCAs) were significantly related to postoperative cerebral hyperperfusion (CHP) after bypass surgery in patients with moyamoya disease (MMD). The present study aimed to introduce a new method to investigate the characteristics of PSCAs hemodynamic sources and their relationships with clinical presentations in adult MMD and to provide preoperative evaluation for recipient vessel selection in MMD bypass surgery. The hemodynamic sources of the PSCAs in 171 symptomatic MMD hemispheres were analyzed by three-dimensional digital subtraction angiography (3D-DSA) combined with magnetic resonance angiography (MRA) fusion imaging. The spatial and temporal characteristics of the hemodynamic sources of the PSCAs and their associations with the patient's demographics, Suzuki stage, and initial onset type were investigated. Six major types of hemodynamic sources in the PSCAs were observed. There was a significant difference between the hemodynamic sources of the PSCAs above and below the SF (P < 0.001). With advancing Suzuki stages, collateral flow to the PSCAs above the SF from the internal carotid arteries (ICAs) significantly decreased, while the non-ICAs increased (P < 0.001). Multivariate analysis revealed that hemodynamic sources of the PSCAs above the SF were significantly associated with patients' initial onset type (P = 0.026). In MMD hemispheres, the hemodynamic sources of the PSCAs above the SF are more varied than those below the SF and present a typical conversion trend from ICAs to non-ICAs with advancing Suzuki stages. Analyzing the hemodynamic sources of the PSCAs can help in understanding the conversion pattern of compensatory vascular systems, predicting episodes in MMD, and preoperatively evaluating suitable recipient vessel selection for bypass surgery to avoid postoperative CHP.

Mutual validation of remote hydraulic estimates and flow model simulations using UAV-borne LiDAR and deep learning-based imaging techniques

Hydraulic modeling plays a pivotal role in various river-related applications, but acquiring precise datasets can be challenging due to complex environments and limited availability of field data. To address these challenges, remote sensing approaches have shown promise, but their widespread scientific use requires validation. This study investigates the utilization of an uncrewed aerial vehicle (UAV)-integrated topo-bathymetric green LiDAR system (GLS) combined with deep learning-based space-time image velocimetry (DL-STIV) techniques to remotely analyze hydraulic properties in the lower Asahi River, Japan. The research compares streamflow measurements with flow model simulations at four transects within a 1.2 km gravel bed channel with vegetation. The results demonstrate that the DL-STIV technique provides reliable velocity estimates, with root-mean-square errors ranging from 0.014 to 0.247 m/s. When using a typical velocity conversion factor of 0.85, the DL-STIV method aligns well with model predictions, yielding coefficient of determination values between 0.850 and 0.959. However, the choice of conversion index (ranging from 0.75 to 0.95) significantly affects accuracy. The study also reveals that remotely estimated discharges are reasonably consistent with model estimates, with errors ranging from 0.026 to 11.124%. However, accuracy is influenced by factors such as the presence of obstacles, uncertainties in remotely sensed water depths, and the choice of reference values. In conclusion, this research demonstrates the suitability and potential of GLS and DL-STIV for remotely analyzing hydraulic properties in rivers. The study also points to the importance of considering potential variations and uncertainties when adopting these techniques for flow modeling and validation purposes.

Nano GeSe2/C anchored in carbon sponge skeleton for free-standing flexible lithium-ion battery electrodes

As a typical conversion alloyed anode material, Germanium selenide (GeSe2) exhibits isotropic lithiation behavior and high theoretical charge-discharge specific capacity. However, pure GeSe2 anode faces significant volume expansion (∼250 %−360 %) and further exploration is needed in the preparation of flexible electrode materials and structural design. Herein, a simple strategy is designed to load GeSe2/C-2 nanoparticles with porous carbon-coated structure on a flexible cross-networking substrate. The 3D network substrate is composed of highly conductive carbon nanotubes and adhesive cotton cellulose fibers. A two-step method involving coating and cross-linking is designed to achieve the fabrication of self-supporting flexible electrodes. As an anode for LIBs, the one layer GeSe2 discs with ∼0.65 mm thickness manifest capacities of 827.1, 744.4, 676.3, and 472.9 mAh g−1 at 0.1, 0.2, 0.5, and 1 A g−1, respectively. This superior Li+ storage performance can be attributed to the positive collective impact from the integration of nano-scale material, low crystalline properties, and carbon sponge skeleton. Furthermore, the GITT tests indicate that the diffusion coefficient of Li+ in the GeSe2-based electrodes ranged from 10−15 to 10−12 cm2/s, and the thickness of the flexible electrode (including two layers) has a negligible impact on its electrochemical performance.

Devising a framework of optogenetic coding in the auditory pathway: Insights from auditory midbrain recordings

Cochlear implants (CIs) restore activity in the deafened auditory system via electrical stimulation of the auditory nerve. As the spread of electric current in biological tissues is rather broad, the spectral information provided by electrical CIs is limited. Optogenetic stimulation of the auditory nerve has been suggested for artificial sound coding with improved spectral selectivity, as light can be conveniently confined in space. Yet, the foundations for optogenetic sound coding strategies remain to be established. Here, we parametrized stimulus-response-relationships of the auditory pathway in gerbils for optogenetic stimulation. Upon activation of the auditory pathway by waveguide-based optogenetic stimulation of the spiral ganglion, we recorded neuronal activity of the auditory midbrain, in which neural representations of spectral, temporal, and intensity information can be found. Screening a wide range of optical stimuli and taking the properties of optical CI emitters into account, we aimed to optimize stimulus paradigms for potent and energy-efficient activation of the auditory pathway. We report that efficient optogenetic coding builds on neural integration of millisecond stimuli built from microsecond light pulses, which optimally accommodate power-efficient laser diode operation. Moreover, we performed an activity-level-dependent comparison of optogenetic and acoustic stimulation in order to estimate the dynamic range and the maximal stimulation intensity amenable to single channel optogenetic sound encoding, and indicate that it complies well with speech comprehension in a typical conversation (65 dB). Our results provide a first framework for the development of coding strategies for future optogenetic hearing restoration.

Experimental study on flow-induced motion and energy conversion for two triangular prisms in tandem arrangement

Experimental tests on two tandem triangular prisms were accomplished in synergistic flow-induced motion (FIM) to collect ocean current energy (OCE) with varied spacing ratios and Reynolds number ranges. Typical FIM responses and energy conversion are discussed and presented. The effects of parameters (system stiffness, spacing ratio, and load resistance) were considered to improve the energy harvesting of the system. The main findings can be summarized as follows: 1) with varied spacing ratios between the two tandem prisms, the active power (Pharn) was up to 1.95 times that of the single triangular prism (STP); 2) In general, the harnessed OCE capacity of the upstream triangular prism (UTP) was improved, while the energy harvesting of the downstream triangular prism (DTP) was suppressed by the interaction of the two prisms, 3) In the tests, electricity was generated atU= 0.516 m/s, and the active power, which consistently increased as flow velocity increased, reachedPharn= 32.24 W, with a corresponding efficiency ofηharn= 10.31%; and 4) The best energy conservation performance for harvesting the OCE occurred atL/D= 5, and the optimal load resistance was found atRL= 11 Ω.

YF3 with Nanostructure: A Rare Earth Metal Fluoride Anode for Lithium‐Ion Batteries

AbstractThe emergence of Li‐ion batteries provides a new path and scheme for carbon neutrality and carbon peak. The performance of lithium‐ion batteries is mainly determined by the electrode material. Among them, transition metal compounds have been widely studied in the anode and cathode materials of lithium‐ion batteries. Here, pure rare earth metal fluoride YF3 was synthesized by solvothermal method and subsequent calcination. The specific capacity of YF3 as a Li‐ion battery anode can increase from 29.3 mAh g−1 to 148.5 mAh g−1 after 1000 cycles at 0.1 A g−1, with a growth rate of up to 407 %. XPS and XRD tests confirmed that the lithium storage process was a typical conversion reaction. The successful application of YF3 in Li‐ion batteries provides a wider range for the selection of Li‐ion electrode materials and also provides a new idea for the exploration of new materials for lithium‐ion batteries.

Phatic Communication in Online English Class Discussions through Facebook Comments

Phatic communication refers to small talks that aim to form ties of personal union between people or the speakers. Especially in this digital age, phatic communication is somehow still used. This research aims to uncover the kinds and functions of phatic communication used by Indonesian students who have been doing online classes through Facebook, responding to their classmates’ material presentations, and having discussions in the comment column. This current study employs the qualitative method with the document analysis technique. The data of this recent study is the phatic communication used by students during the online course through Facebook, and the data was examined through document analysis techniques from the students’ Facebook comments activity in the form of words, phrases, clauses, and sentences related to phatic expressions. Moreover, the data was analyzed through the following steps: 1) labeling the related data; 2) classifying the data into its types and functions; 3) interpreting the data findings; and 4) drawing conclusions. The study’s main finding is the appearance of phatic expressions, for instance, greeting, thankfulness, compliment, apology, encouragement, and wishing to each other. As the typical conversation is made online through social media platforms such as Facebook, we suggest that some language or conversation styles like abbreviations, non-standard spelling, and emojis have also appeared.

Defective Photocathode: Fundamentals, Construction, and Catalytic Energy Conversion

AbstractThe development of a long‐term and sustainable energy economy is one of the most significant technological challenges facing humanity. Photoelectrochemical (PEC) technology is considered as the most attractive route for converting solar energy into chemical energy. However, the slow reaction kinetics of PEC oxidation and reduction greatly hinder its practical application. To address this issue, engineering photoelectrodes with various defects can significantly improve their catalytic performance, which can not only regulate catalyst electronic structure but also promote charge transfer/separation by serving as an active/adsorption/energy storage site. Herein, the defect engineering strategies for photoelectrodes are systematically summarized, focusing on the latest progress in defective photocathode for energy conversion. First, an overview of defect types, basic principles of photocathode, and the positive role of defects in the photocathode are provided. Second, the construction strategies and characterization methods of defective photocathode are summarized. Then, the progress of typical energy conversion applications, including hydrogen production, CO2 reduction, and nitrogen reduction over defective photocathode, is reviewed, highlighting the crucial role of defects in high catalytic performance. Finally, the challenges and future prospects of defective photocathode are discussed, aiming to bring new opportunities for the development of photocathode through defect engineering.