Simple Transfer Research Articles

Plasmid-free production of the plant lignan pinoresinol in growing Escherichia coli cells

BackgroundThe high-value aryl tetralin lignan (+)-pinoresinol is the main precursor of many plant lignans including (-)-podophyllotoxin, which is used for the synthesis of chemotherapeutics. As (-)-podophyllotoxin is traditionally isolated from endangered and therefore limited natural sources, there is a particular need for biotechnological production. Recently, we developed a reconstituted biosynthetic pathway from (+)-pinoresinol to (-)-deoxypodophyllotoxin, the direct precursor of (-)-podophyllotoxin, in the recombinant host Escherichia coli. However, the use of the expensive substrate (+)-pinoresinol limits its application from the economic viewpoint. In addition, the simultaneous expression of multiple heterologous genes from different plasmids for a multi-enzyme cascade can be challenging and limits large-scale use.ResultsIn this study, recombinant plasmid-free E. coli strains for the multi-step synthesis of pinoresinol from ferulic acid were constructed. To this end, a simple and versatile plasmid toolbox for CRISPR/Cas9-assisted chromosomal integration has been developed, which allows the easy transfer of genes from the pET vector series into the E. coli chromosome. Two versions of the developed toolbox enable the efficient integration of either one or two genes into intergenic high expression loci in both E. coli K-12 and B strains. After evaluation of this toolbox using the fluorescent reporter mCherry, genes from Petroselinum crispum and Zea mays for the synthesis of the monolignol coniferyl alcohol were integrated into different E. coli strains. The product titers achieved with plasmid-free E. coli W3110(T7) were comparable to those of the plasmid-based expression system. For the subsequent oxidative coupling of coniferyl alcohol to pinoresinol, a laccase from Corynebacterium glutamicum was selected. Testing of different culture media as well as optimization of gene copy number and copper availability for laccase activity resulted in the synthesis of 100 mg/L pinoresinol using growing E. coli cells.ConclusionsFor efficient and simple transfer of genes from pET vectors into the E. coli chromosome, an easy-to-handle molecular toolbox was developed and successfully tested on several E. coli strains. By combining heterologous and endogenous enzymes of the host, a plasmid-free recombinant E. coli growing cell system has been established that enables the synthesis of the key lignan pinoresinol.

Flexural behaviour and shear capacity of RC flat plate sections during fire exposure

PurposeFire safety is a pivotal requirement in building codes. Prescribed design criteria have been the norm to achieve it, which imposes limitations on engineers, including the inability to accommodate new solutions/materials. The shift towards performance-based design offers the potential to address shortcomings of the prescribed design. However, this shift also significantly increases the workload on structural engineers without a corresponding increase in their engineering fees. Simplified design tools are needed to assist engineers in this transition.Design/methodology/approachThe paper is divided into sections investigating equivalent standard fire duration, thermal deformations, flexural behaviour and shear capacity of flat slabs when exposed to fire. The first section conducts a parametric study correlating equivalent and realistic fire durations using the average internal temperature profile (AITP) method, resulting in statistical equations estimating equivalent fire duration. The second section evaluates thermal deformations and flexural behaviour through a parametric study considering various parameters. This section results in statistical equations estimating thermal deformations and flexural behaviour of flat slab sections during fire exposure. The final section focuses on shear capacity, developing simplified heat transfer formulas and statistical equations predicting compression zone depth reduction. The section presents methodologies predicting flat slab sections' one-way and two-way shear capacities during fire exposure.FindingsStructural engineers can use the proposed methods for daily design work without applying complex heat transfer calculations. When the equivalent standard fire duration is utilized, a flat slab’s thermal deformations, flexural behaviour and shear capacity under an actual fire condition can be calculated. As such, the methods would be highly beneficial in assessing the structural integrity of a building during an active fire incident.Originality/valueThe paper provides engineers with the tools required to evaluate the safety of flat slab sections during fire exposure. The methodologies presented in the paper enable engineers to use performance-based design for slab sections by (1) converting any real fire scenario to a standard fire with an equivalent duration, (2) assessing their thermal behaviour, (3) evaluating their flexural behaviour and (4) evaluating their flexural and shear capacities. The paper concludes with a case study example demonstrating the detailed application of the developed methods.

Analysis of fatigue damage of hot rolling work rolls coupled with wear effect

During the hot rolling process, the work roll experiences cyclic contact stress due to the deformation of the strip steel, as well as thermal stress from periodic heating and cooling. The surface failure of the work roll results from the combined effects of wear and fatigue damage. This study proposes a comprehensive approach to analyzing coupled wear and fatigue damage using a method based on the Manson-Coffin equation, modified slope formula, and the Miner criterion. Finite element models were developed to simulate simplified heat transfer and thermal coupling, taking into account the actual rolling parameters and high-temperature material properties of the work roll. The evolution of the physical field of the work roll during the rolling process was analyzed. The analysis of these models revealed that the maximum strain on the work roll occurred at the rolling exit and was predominantly influenced by temperature. The effects of rolling speed and temperature on work roll strain varied, with fatigue damage being significantly reduced when wear was considered compared to scenarios where wear was not accounted for, under the same number of cycles.

Femtosecond laser-induced plasma-assisted backward deposition of robustly adherent porous carbon films on glass substrates

The simple and rapid production and transfer of high-quality carbon materials are crucial for the flexible and efficient fabrication of carbon-based electronic devices. Recently, a laser-assisted transfer method combining laser-induced carbonization and transfer printing was demonstrated for the one-step preparation and transfer of patterned laser-induced carbon films to transparent substrates. However, this method is limited by insufficient robustness and weak adhesion of the carbon film post-transfer. Herein, we developed a non-contact laser-induced plasma-assisted deposition method to deposit robustly adherent porous carbon films on glass substrates. By well-adjusting the laser parameters and inserting spacers with adjustable thickness, laser-induced plasma ablation replaced direct laser ablation during femtosecond laser scanning of the substrate-polyimide-carrier sandwich structure, resulting in micro-channels with a carbon-glass recast layer instead of easily peelable flakes on the glass substrate. This hierarchical structure significantly enhances the adhesion between the laser-induced carbon film and the glass substrate, ensuring outstanding stability of the deposited carbon film under various adhesion tests. Furthermore, compared to carbon films prepared by the laser-assisted transfer method, the obtained carbon films are hydrophilic, low-resistance, and porous, facilitating the fabrication of energy storage devices. To demonstrate its practical application, a planar carbon-based micro-supercapacitor was fabricated on glass, exhibiting excellent electrochemical and cycling performance.

Diagnostic performance of an automated robot for MALDI target preparation in microbial identification.

The MBT Pathfinder is an automated colony-picking robot designed for efficient sample preparation in matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. This article presents results from three key experiments evaluating the instrument's performance in conjunction with MALDI Biotyper instrument. The method comparison experiment assessed its clinical performance, demonstrating comparable results with gram-positive, gram-negative, and anaerobic bacteria (scores larger than 2.00) and superior performance over simple direct yeast transfer (score: 1.80) when compared to samples prepared manually. The repeatability experiment confirmed consistent performance over multiple days and labs (average log score: 2.12, std. deviation: 0.59). The challenge panel experiment showcased its consistent and accurate performance across various samples and settings, yielding average scores between 1.76 and 2.19. These findings underline the MBT Pathfinder as a reliable and efficient tool for MALDI-TOF mass spectrometry sample preparation in clinical and research applications.

Understanding the Significance of Censored Data

Abstract The regulatory world seeks to ascertain if the levels of chemicals in the environment are at a “safe” level. Such an objective leads to dismissing results that are reported as below the detection level (BDL) as being satisfactory. Although this meets the regulatory objective, when attempting to understand the mechanisms that lead to low concentration, such data can be very important. As such, it must be treated in a statistically appropriate manner. The BDL or censored data need to be incorporated into evaluations. Moreover, there is a need to understand the data’s limits of precision. Right censored data are routinely handled for toxicological and reliability studies. BDL values produce left censored values that with a simple transfer can be flipped to right censored values by subtracting all values from a number larger than the data. Then the data can be processed using the statistical tests familiar to toxicologists. Examples of low-level stack emission data and ambient air data are examined in this article. The examples indicate that data should be clearly qualified to ensure that the reader understands the limitations. Using censored data to evaluate factors contributing to measured levels can lead to erroneous conclusions, raise concerns in the public, and lead to potentially unnecessary remedial efforts.

New Sustainable Fintech Business Models Created by Open Application Programming Interface Technology: A Case Study of Korea’s Open Banking Application Programming Interface Platform

Fintech facilitates financial inclusion by introducing new sustainable and accessible business models in developing countries. Open banking API technology is used by various fintech businesses in both developing and developed countries, with varying effects on financial markets. It changes the financial market distribution structure by separating financial product manufacturing and distribution and intensifying competition between traditional financial institutions and fintech companies. Fintech companies innovate by using this tool to create new business models. In December 2019, Korea established a standardized “open banking API platform”, sharing an interbank payment network with fintech companies. It has since shown explosive growth, surpassing the trading volume of the UK, the country that introduced open banking APIs for the first time. This study analyzes new business models fintech companies created using this API technology. Based on existing literature, statistics from the platform operator (the Korea Financial Telecommunications and Clearings Institute), and investigations of 30 Korean fintech mobile applications, this study analyzes new fintech business models that provide financial services using this platform. These companies create sustainable business models by combining multiple APIs. Four representative business models (simple funds transfer, simple payment, cross-border remittance, and asset management) are analyzed to reveal how fintech companies create business models with open APIs.

A Design of an SMTP Email Server

This study developed a mail server program using Socket API and Python. The program uses the Hypertext Transfer Protocol (HTTP) to receive emails from browser clients and forward them to actual email service providers via the Simple Mail Transfer Protocol (SMTP). As a web server, it handles Transmission Control Protocol (TCP) connection requests from browsers, receives HTTP commands and email data, and temporarily stores the emails in a file. Simultaneously, as an SMTP client, the program establishes a TCP connection with the actual mail server, sends SMTP commands, and transmits the previously saved emails. In addition, we also analyzed security issues and the efficiency and availability of this server, providing insights into the design of SMTP mail servers.

Assessing Nonlinear Polarization in Electrochemical Cells Using AC Impedance Spectroscopy

Electrochemical energy storage and conversion devices are used to power a range of electrical loads including portable electronics, electric vehicles, and utility grids. The energy efficiency of these systems decreases with increasing current load due to energy losses (in the form of heat) associated with different processes. Electrochemical impedance spectroscopy (EIS) is a nondestructive technique commonly used to assess rate-limiting steps in electrochemical devices. Most EIS measurements for energy storage devices are only performed around open-circuit and do not probe system behavior under non-zero biases where these devices operate. Despite its widespread use, this approach does not provide information about the relative overpotentials associated with coupled nonlinear processes (e.g., diffusion limited redox reactions) commonly encountered in these systems. Furthermore, ambiguous terms such as equivalent series resistance and interfacial resistance can lead to confusion and data misinterpretation. For example, Ohm’s law cannot be applied to calculate nonlinear overpotentials using a resistance that was measured from a locally linear response.To determine overpotentials in nonlinear systems using EIS, one must integrate the individual resistive elements of the equivalent circuit as a function of steady state current. Recent experimental work has used this method to decouple ohmic, kinetic, and transport overpotentials in redox flow batteries. In these prior studies, impedance elements were derived, but analytical expressions for the corresponding overpotentials were not presented.While integrated resistance measurements are a powerful experimental tool, a more rigorous mathematical framework describing the approach is needed. The present work bridges this gap by: (i) deriving a general impedance expression for coupled charge transfer and diffusion processes and (ii) integrating the individual resistive elements as a function of steady-state current to obtain global polarization relationships. Analytical expressions for diffusion overpotentials are obtained for special cases, and numerical methods are applied when closed-form expressions do not exist. The work considers three model electrode geometries (planar, cylindrical, and spherical) and two diffusion boundary types (reflective and transmission). Finally, this treatment is extended to macroscopically homogenous porous electrodes which are relevant for describing practical devices.This presentation will highlight how measuring impedance at different steady-state biases provides critical insights on the rate-limiting processes in energy storage devices. While this work focuses on a simple Faradaic charge transfer process, the method can be used to evaluate other nonlinear phenomena in electrochemical power supplies. For example, the resistance of passive films (e.g., solid electrolyte interphase layer) in Li-ion batteries is typically only probed near open-circuit. Similarly, literature on solid-state batteries commonly uses ambiguous terms such as interfacial resistance to describe rate-limiting processes. For these more complex systems, integrating the resistive elements can provide insights on how these phenomena influence device efficiency. Overall, combining these experimental observations with physical models derived using the approach illustrated herein represents a powerful tool to guide component/system design and improve device performance. Acknowledgements This research was conducted at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy (DOE). This work is sponsored by the U.S. Department of Energy in the Office of Electricity through the Energy Storage Research Program and the Office of Energy Efficiency and Renewable Energy (EERE) in the Vehicle Technologies Office (VTO) through the Advanced Battery Materials Research (BMR) Program.

Dynamic thermal runaway evolution of Li-ion battery during nail penetration

The nail penetration test is widely adopted to evaluate the safety of lithium-ion batteries by triggering the internal short circuit. This work compares the phenomena, temperature rise rate, surface temperature, and mass loss under the penetration test for different nail materials, nail diameters, and cell SOCs. The thermal runaway behaviour and characteristics of these test cells are studied in depth. The results show that the maximum temperature and temperature rise rate of the cell increase with the increase of SOC. The maximum temperature and the temperature rise rate of the cell decrease with the increase of the nail diameter. Under high SOC conditions (greater than 75 % SOC), the more conductive nail increases the release of Joule heat generation inside the battery, which leads to a more intense thermal runaway behaviour. At low SOC (less than 50 % SOC), the more conductive nail promote cooling, which reduces the intensity of thermal runaway. However, non-conductive nails show the exact opposite effect. This dual effect of different nail materials was elucidated by a simplified heat transfer analysis. By calculating the heat production and heat dissipation during the thermal runaway process, the effects of the nail material and the cell SOCs on the thermal runaway behaviour of the battery can be summarized. This work deepens the understanding of the safety of batteries under external shocks and provides new scientific insights into battery design and its safety testing.

RadVolViz: An Information Display-Inspired Transfer Function Editor for Multivariate Volume Visualization.

In volume visualization transfer functions are widely used for mapping voxel properties to color and opacity. Typically, volume density data are scalars which require simple 1D transfer functions to achieve this mapping. If the volume densities are vectors of three channels, one can straightforwardly map each channel to either red, green or blue, which requires a trivial extension of the 1D transfer function editor. We devise a new method that applies to volume data with more than three channels. These types of data often arise in scientific scanning applications, where the data are separated into spectral bands or chemical elements. Our method expands on prior work in which a multivariate information display, RadViz, was fused with a radial color map, in order to visualize multi-band 2D images. In this work, we extend this joint interface to blended volume rendering. The information display allows users to recognize the presence and value distribution of the multivariate voxels and the joint volume rendering display visualizes their spatial distribution. We design a set of operators and lenses that allow users to interactively control the mapping of the multivariate voxels to opacity and color. This enables users to isolate or emphasize volumetric structures with desired multivariate properties. Furthermore, it turns out that our method also enables more insightful displays even for RGB data. We demonstrate our method with three datasets obtained from spectral electron microscopy, high energy X-ray scanning, and atmospheric science.

Assessing Intra-Bundle Impregnation in Partially Impregnated Glass Fiber-Reinforced Polypropylene Composites Using a 2D Extended-Field and Multimodal Imaging Approach.

This study evaluates multimodal imaging for characterizing microstructures in partially impregnated thermoplastic matrix composites made of woven glass fiber and polypropylene. The research quantifies the impregnation degree of fiber bundles within composite plates manufactured through a simplified compression resin transfer molding process. For comparison, a reference plate was produced using compression molding of film stacks. An original surface polishing procedure was introduced to minimize surface defects while polishing partially impregnated samples. Extended-field 2D imaging techniques, including polarized light, fluorescence, and scanning electron microscopies, were used to generate images of the same microstructure at fiber-scale resolutions throughout the plate. Post-processing workflows at the macro-scale involved stitching, rigid registration, and pixel classification of FM and SEM images. Meso-scale workflows focused on 0°-oriented fiber bundles extracted from extended-field images to conduct quantitative analyses of glass fiber and porosity area fractions. A one-way ANOVA analysis confirmed the reliability of the statistical data within the 95% confidence interval. Porosity quantification based on the conducted multimodal approach indicated the sensitivity of the impregnation degree according to the layer distance from the pool of melted polypropylene in the context of simplified-CRTM. The findings underscore the potential of multimodal imaging for quantitative analysis in composite material production.

Three approaches on estimating geometric sensitivities in radiative transfer with Monte Carlo

The Monte Carlo method, renowned for its ability to handle the spectral and geometric complexities of 3D radiative transfer, is extensively utilized across various fields, including concentrated solar power design, atmospheric science, and computer graphics. The success of this method also extends to the estimation of sensitivity—the derivative of an observable with respect to a given system parameter, which is, however, particularly challenging when these parameters involve geometric deformation. Bridging statistical physics and computer graphics, distinct methodologies have emerged within these fields for estimating geometric sensitivity, each employing unique terminologies and mathematical frameworks, leading to seemingly disparate approaches. In this paper, we review the three main approaches to sensitivity estimation: (1) Expectation Differentiation, which employs a vectorized Monte Carlo algorithm to simultaneously estimate the intensity and its sensitivity; (2) Differentiable Rendering, predominantly used in computer graphics and applied in numerous contexts; (3) Transport Model for Sensitivity, which conceptualizes sensitivity as a physical quantity with its own transport equations and boundary conditions, thereby facilitating engineering and physics analyses. We aim to enhance readers’ ability to tackle sensitivity-related challenges by providing a comparative understanding of these three perspectives. We achieve this through a simplified one-dimensional radiative transfer case study, offering an accessible platform for comparing and classifying these approaches based on their theoretical underpinnings and practical application in Monte Carlo algorithms.

Color-tunable graphene quantum dots via one-step nitrogen-induced intramolecular charge transfer for in vivo/vitro aminotransferase fluorescence sensing

Monitoring aspartate aminotransferase (AST) has been demonstrated to be a sensitive sign of liver dysfunction and an essential method for determining the health status of the living body. The quantitative analysis of AST in vivo/vitro is still challenged by complicated processes, expensive equipment, and/or limited sensitivity. A colorimetric assay using multicolored fluorescent nanomaterials holds great promise in vivo/vitro sensing for visual and highly sensitive disease diagnosis. However, achieving a one-step synthesis of multicolored fluorescence (FL) GQDs probe presents challenges. Herein, we successfully designed novel multicolored GQDs with a high quantum yield (QY) of 60.7 % via a simple nitrogen-induced intramolecular charge transfer (ICT) approach. Leveraging the non-toxic and color-tunable properties of N-GQDs, we developed an innovative N-GQDs-based FL test paper for sensitive colorimetric on-site detection of AST, employing the FL colorimetric method based on the transamination reaction. The FL quenching intensity demonstrated an excellent linear relationship with the concentration of AST within the range of 2.0−60.0 U/L, achieving an impressively low limit of detection (LOD) as low as 0.065 U/L. Moreover, the N-GQDs were utilized for AST in vivo detection and FL imaging in living zebrafish, further showcasing their potential in various applications such as liver disease diagnosis, assessment of myocardial damage, and monitoring of drug and toxic poisonings.

Generalisation capabilities of machine-learning algorithms for the detection of the subthalamic nucleus in micro-electrode recordings.

Micro-electrode recordings (MERs) are a key intra-operative modality used during deep brain stimulation (DBS) electrode implantation, which allow for a trained neurophysiologist to infer the anatomy in which the electrode is placed. As DBS targets are small, such inference is necessary to confirm that the electrode is correctly positioned. Recently, machine learning techniques have been used to augment the neurophysiologist's capability. The goal of this paper is to investigate the generalisability of these methods with respect to different clinical centres and training paradigms. Five deep learning algorithms for binary classification of MER signals have been implemented. Three databases from two different clinical centres have also been collected with differing size, acquisition hardware, and annotation protocol. Each algorithm has initially been trained on the largest database, then either directly tested or fine-tuned on the smaller databases in order to estimate their generalisability. As a reference, they have also been trained from scratch on the smaller databases as well in order to estimate the effect of the differing database sizes and annotation systems. Each network shows significantly reduced performance (on the order of a 6.5% to 16.0% reduction in balanced accuracy) when applied out-of-distribution. This reduction can be ameliorated through fine-tuning the network on the new database through transfer learning. Although, even for these small databases, it appears that retraining from scratch may still offer equivalent performance as fine-tuning with transfer learning. However, this is at the expense of significantly longer training times. Generalisability is an important criterion for the success of machine learning algorithms in clinic. We have demonstrated that a variety of recent machine learning algorithms for MER classification are negatively affected by domain shift, but that this can be quickly ameliorated through simple transfer learning procedures that can be readily performed for new centres.

Pemeliharaan Dan Pengamanan Arsip Keluarga Melalui Tindakan Alih Media

This Community Service activity is carried out in partnership with the target group, which consists of the mothers of students from the Play Group and Kindergarten of Cahya Hati, located in Mulyoagung Village, Dau District, Malang Regency, East Java. The purpose of this activity is to provide understanding and training to mothers in managing family archives through media conversion. The reason for choosing the target partner is that the mother is the one who manages the daily life of the family. One of them is in managing family documents. Family documents need to be archived to record information and be easily retrieved when needed. The transfer of archival media is carried out with the aim of ensuring the safety of family archives, such as from the dangers of flooding, fire, and other hazards. The community service activities were conducted using methods of lectures, discussions, and simple media transfer training, followed by the storage of family archives resulting from the media transfer actions. The result of this community service activity is that the mothers involved gained experience in transferring family archive media, and then immediately practiced it on their own family documents.

Composite structures with embedded fiber optic sensors: A smart propellant tank for future spacecraft applications

Modern spacecraft and launch vehicle design is more oriented towards reducing system-level design and assembly complexities. In order to maintain high overall system performance while reducing these complexities, the use of smart materials and smart structural components is a well-known practice and is currently of rising interest to space systems' designers. The paper discusses a concept of smart space structures, in particular, a carbon fiber composites structure embedded with Optical Fiber Sensors (OFS) for spacecraft and launch vehicle applications. This study highlights the operational requirements for such tank and the smart features enabled by the optical fiber sensors. For the latter aspect, a quantitative comparison between Fiber Bragg Grating sensors (FBGs) and Distributed Optical Fiber Sensors (DOFS) based on Optical Frequency Domain Reflectometry (OFDR) is presented to state their core performance parameters, such as the sensitivity, sensing range, dynamic measurement capability, and spatial resolution. The increased performance and reliability in harsh environments associated with fiber optic sensors come with a reduction in size, mass, and power consumption compared to the conventional electronic sensors. Optical fiber sensors embedded in carbon fiber structures have proven their capability in providing accurate real-time measurements of temperature and monitoring structural integrity while detecting precisely possible points of rupture and failure as discussed and demonstrated in the literature review. The applications of fiber optic sensing in smart propellant tanks may extend to detecting fluid leakage, also providing increased precision in propellant gauging through temperature mapping, and can be used in on-ground qualification, pre-flight testing, as well as in-orbit operation, condition, and structural health monitoring. The article presents a statement for an optimal FOS embedding approach in composite pressure vessels and discusses the related placement and orientation method for the fiber optic sensors, coupled with a one component simplified analytical stress-strain transfer model deriving the stress component along the maximum principal direction (i.e., σMaxPrincipal). The novel approach is believed to serve the optimal employment of embedded FOS in composite structures, e.g., pressure vessels and light-weight structures in spacecraft, among other applications. The simplified model is believed to pave the way for effective data interpretation and processing, utilizing the available limited computational resources on-board the spacecraft.

In situ Raman monitoring of studtite formation under alpha radiolysis in 18O-labeled water

Studtite [(UO2)(O2)(H2O)2]·2(H2O) is a secondary phase precipitating during the alteration of uranium-bearing materials. The mechanistic link between the formation of uranyl and peroxide bonds in the solid and the nature of the oxidizing species produced by water radiolysis remains to be elucidated. In order to improve our understanding of these mechanisms, an original experimental methodology in the presence of 18O isotopes and Raman spectroscopy has been developed. It appears that there is a direct chemical relationship between the peroxo ligands inside studtite and the peroxide entities of H2O2 molecule into the solution. The link between H2O2 formation mechanism in solution by the radiolysis of water, the nature of the radiation and the isotopy of the peroxo ligands inside studtite has been described thanks to a coherent set of experimental data. For the uranyl UO22+ ions, the characterization of its isotopy allows to specify the mechanism of oxidation at the UO2 /water interface. The isotopic configurations observed for the uranyl ion inside studtite, can be explained by assuming an oxidation mechanism of UO2 involving both a simple transfer of electrons by interaction with H2O2 and the incorporation of oxygen atoms from the solution into the fluorite structure via OH° radicals.

Experimental and theoretical study on the smoldering combustion of size-fractioned forest duff particles

Smoldering combustion process has been suggested as a new method potentially useful in the treatment of biosolids. Natural forest duff (FD) often consists of organic fuel layers with varying particle sizes, yet the influence of the size-fractioned particles on the smoldering combustion dynamics in terms of the heat and mass transfer is not well understood. In this study, the oxidative pyrolysis and smoldering behavior of FD samples with four particle sizes (0 < d1 ≤ 0.425 mm, 0.425 < d2 ≤ 1 mm, 1 < d3 ≤ 2 mm, 2 < d4 ≤ 4 mm) were experimentally and theoretically investigated. Micro-scale thermo-gravimetric (TG) analysis, and a four-step kinetic model incorporating water evaporation, FD pyrolysis, FD oxidation and char oxidation showed that the activation energy of the FD pyrolysis and the ash content are negatively correlated, while the activation energy of the char oxidation increases from 87.26 kJ mol−1 to 119.22 kJ mol−1 with the particle size increasing from d1 to d4. Furthermore, the order of the combustion performance of the FD samples is shown as d1<d2<d4<d3. A series of laboratory-scale smoldering experiments revealed that the peak smoldering temperature increases with the fuel depth while the horizontal spread rate decreases with the fuel depth. Both the peak mass loss rate and the smoldering duration presented a reverse order (d1>d2>d4>d3) of the combustion performance found in the TG tests. A simplified heat transfer analysis qualitatively revealed the beneficial effects of the size-fractioned particles on the smoldering spread rate, while a mass transfer analysis revealed the favorable and adverse influences of the particle size on the kinetic-controlled and diffusion-controlled char oxidation rate, respectively. These findings verify that particle sizes alter the FD physicochemical properties (e.g., specific surface area, bulk density, porosity, permeability, chemical components, and lower calorific value), which in return impact the chemical kinetics, heat and mass transfer process in smoldering combustion. This work provides new insights into the effects of the size-fractioned particles on smoldering combustion, ultimately improving the fundamental understanding for optimizing particle sizes for energy conversion and usage.

Fabrication of novel SiOxNy/SWCNT laminate-type composite protective coating using low-temperature approach

Multifunctional thin films are becoming extremely popular in many technological fields. An increase in their functionality can be achieved by the creation of nanocomposite structures. This study represents novel thin composite coatings with a horizontally oriented single-walled carbon nanotube (SWCNT) filler inside a silicon oxynitride (SiOxNy) matrix obtained by (i) low-temperature thermal curing or by (ii) UV radiation-induced curing. The SiOxNy/SWCNT composite structures were prepared by simple dry transfer of a SWCNT film into a perhydropolysilazane (PHPS) polymer matrix film deposited by the spin-coating technique followed by curing. The structural, morphological, and optical properties of the SiOxNy/SWCNT composite films were studied using HR-SEM/EDX, ATR-FTIR, and UV–Vis spectroscopy. It was found that SWCNT films were uniformly transferred into the PHPS matrix, maintaining their horizontally oriented close-packed structure, and avoiding the problem of agglomeration, thereby forming a laminate-type composite. SWCNTs had no effect on the curing process of the PHPS matrix. The SWCNT concentration remained relatively low, resulting in highly transparent composite films. An antireflection effect in the composite film relative to the transmission of the SWCNT film was observed. The results indicate that SiOxNy/SWCNT composites are attractive for applications as protective, antireflective optical coatings.