Two-step Method Research Articles

Reusable adsorbent of magnetite in mesoporous carbon for antibiotic removal.

This study aims to evaluate the feasibility of an innovative reusable adsorbent through adsorption-degradation sequence for antibiotic removal from water. The magnetite/mesoporous carbon adsorbent was prepared using a two-step method of (i) in situ impregnation of magnetite precursor during resorcinol formaldehyde polymerization and (ii) pyrolysis at elevated temperature (800 °C). XRD spectra confirmed that magnetite (Fe3O4) was the only iron oxide species present in the adsorbent, and thermogravimetric analysis revealed that its content was 10 wt%. Nitrogen sorption analysis showed that Fe3O4/carbon features a high fraction of mesopores (> 80 vol.%) and a remarkable specific surface area value (246 m2g-1), outstanding properties for water treatment. The performance of the adsorbent was examined in the uptake of three relevant antibiotics. The maximum adsorption uptakes were ca. 76mgg-1, ca. 70mgg-1, and ca. 44mgg-1 for metronidazole, sulfamethoxazole, and ciprofloxacin, respectively. All adsorption curves were successfully fitted with Langmuir equilibrium model. The regeneration of adsorbent was carried out using Fenton oxidation under ambient conditions. After three consecutive runs of adsorption-regeneration, Fe3O4/carbon maintained its performance almost unchanged (up to 95% of its adsorption capacity), which highlights the high reusability of the adsorbent.

Optical properties of lead-free Cs3Bi2I9 nanowire arrays prepared by template

Bismuth-based (Bi) perovskites have garnered significant interest as alternatives to lead-based (Pb) perovskites in photoelectric applications due to their non-toxicity and diverse structural properties. However, the inherent high limitation of electrons presents a significant challenge to their further utilization in various applications. Herein, all-inorganic Cs3Bi2I9 nanowire arrays have been successfully prepared by AAO template combined with the two-step method of low-temperature solution. Compared to the Cs3Bi2I9 film, the Cs3Bi2I9 nanowire arrays obtained the higher photoluminescence intensity, indicating a strong interaction between Cs3Bi2I9 and AAO, resulting from the significant weakening of the high electron confinement in the valence band of Cs3Bi2I9, which presenting as the valence band of the Cs3Bi2I9-AAO is mainly contributed by the O 2p orbital, while the conduction band does not change significantly. In addition, the Cs3Bi2I9 nanowire arrays have been demonstrated with the enhanced environmental and thermal stability, which maintain 90 % of their initial photoluminescence intensity after 120 h (in a vacuum) heating at 80 °C or after 10 days in the air (relative humidity of 40 %).

High-Throughput Roll-to-Roll Processed Large-Area Perovskite Solar Cells Using Rapid Radiation Annealing Technique.

The development of a stable roll-to-roll (R2R) process for flexible large-area perovskite solar cells (PSCs) and modules is a pressing challenge. In this study, we introduced a new R2R PSC manufacturing system that employs a two-step deposition method for coating perovskite and uses intensive pulsed light (IPL) for annealing. This system has successfully fabricated small-sized cells and the first-ever large-sized, R2R-processed flexible modules. A key focus of our work was to accelerate the conversion of PbI2 to perovskite. To this end, we utilized IPL annealing and incorporated additives into the PbI2 layer. With these modifications, the R2R-processed perovskite films achieved a power conversion efficiency (PCE) of 16.87%, representing the highest reported value for R2R two-step processed PSCs. However, these cells exhibited hysteresis in reverse and forward PCE measurements. To address this, we introduced a dual-annealing process consisting of IPL followed by a 2-min thermal heating step. This approach successfully reduced hysteresis, resulting in low-hysteresis, R2R-processed flexible PSCs. Moreover, we fabricated large-scale flexible modules (10 × 10 cm2) with a PCE of 11.25% using the dual-annealing system, marking a significant milestone in this field.

The effect of off-balance sheet activities on credit risk of African banks

Purpose The purpose of this study is to analyze the effect of off-balance sheet activities on the credit risk of African banks. Design/methodology/approach The theory about the relationship between off-balance sheet activities and bank risk was used to construct a conceptual model of the effect of off-balance sheet on credit risk in an African context. The accounting approach is chosen by collecting accounting data extracted from the annual reports of 24 private and conventional African banks during the period 2010–2019. Both statistical and empirical studies are conducted. The statistical study aims to give a description of sample banks in terms of off-balance sheet activities and key financial indicators. The empirical study has the goal of exploring the correlations between, on the one hand, credit risk and, on the other hand, off-balance sheet ratio and control variables (bank- and country-specific variables). This study is based on dynamic panels using the two-step generalized method of moments technique to estimate regressions between credit risk and the explanatory variables. Findings The statistical study reveals that sample banks use moderately off-balance sheet activities; most of them use essentially guarantees and letters of credit, have satisfactory financial indicators and are slightly exposed to credit risk. The empirical results from the two-step generalized method of moments technique disclose that off-balance sheet activities have an intensifying effect on the credit risk of African banks. However, the increasing effect can be minimized when African banks use moderately off-balance sheet activities. Practical implications Using judiciously off-balance sheet activities does not exacerbate the exposure of African banks to credit risk. Therefore, managers of African banks are recommended to maintain a moderate level of off-balance sheet activities, especially guarantees and letters of credit. Originality/value The findings of this study eliminate the opacity about the effect of off-balance sheet activities on credit risk. Moreover, this study fulfills the huge gap in the related literature by completing the scarcity of recent studies, considering all items of the off-balance sheet, focusing on the African context, describing off-balance sheet activities and financial indicators of sample banks due to a statistical study and estimating regressions of dynamic panels between credit risk and both bank-specific and country-specific variables due to a two-step generalized method of moments technique.

Synergistic effect of stearic acid/bismuth oxychloride/cupric oxide for thermal storage applications: preparation, stability, rheological and thermophysical analysis

Abstract The present study reports the preparation of nanophase change materials (NPCMs) using a two-step method with an optimized ratio of 0.5 wt.% of nanoparticles for thermal storage applications. Bismuth oxychloride (BiOCl), cupric oxide (CuO), and a mixture of BiOCl/CuO (composite) were used as nanoparticles, and stearic acid was used as the PCM. The crystallography, chemical/functional groups and morphologies of the prepared NPCMs have been analysed by XRD, FT-IR and SEM, respectively. Observations revealed that the presence of nanoparticles in NPCMs did not affect crystal formation or chemical disruption of molecular interactions. TGA was used to analyse the thermal stability and rate of deterioration of the NPCMs. The deterioration of the PCM occurs at 243℃ with a weight loss of 1.3% while 0.5 wt.% concentrated BiOCl, CuO, and composite NPCMs exhibit weight losses of 1.8%, 2.3%, and 3.4%, respectively at 257℃, 262℃ and 258℃. In the DSC study, the phase-changing attributes of the NPCMs manifested in the onset temperature range between 53.4°C and 59.8°C. The potential enthalpy of the PCM is 209.1 kJ/kg, whereas those of the 0.5 wt.% concentrated BiOCl, CuO, and composite NPCMs are 204.6, 198.3, and 201.7 kJ/kg, respectively. However, the enhanced thermal conductivities of 0.5 wt.% concentrated BiOCl, CuO, and the composite NPCMs are 0.18, 0.22, and 0.20 W/(m.℃), respectively, which are 5.9%, 29.4% and 17.6% greater than that of PCM. Additionally, the congruent melting rate increased by 31% for 0.5 wt.% CuO concentrated NPCM; therefore, it is a potential candidate than other NPCMs/PCM. Cyclic tests were conducted to assess the reliability of the NPCMs, and compatible results were obtained even after 500 cycles. The findings of this work indicate that all the prepared NPCMs could be a viable option for practical applications, including thermal comfort buildings, solar heating, and electronic cooling.

Efficient Structure from Motion for Large-Size Videos from an Open Outdoor UAV Dataset

Modern UAVs (unmanned aerial vehicles) equipped with video cameras can provide large-scale high-resolution video data. This poses significant challenges for structure from motion (SfM) and simultaneous localization and mapping (SLAM) algorithms, as most of them are developed for relatively small-scale and low-resolution scenes. In this paper, we present a video-based SfM method specifically designed for high-resolution large-size UAV videos. Despite the wide range of applications for SfM, performing mainstream SfM methods on such videos poses challenges due to their high computational cost. Our method consists of three main steps. Firstly, we employ a visual SLAM (VSLAM) system to efficiently extract keyframes, keypoints, initial camera poses, and sparse structures from downsampled videos. Next, we propose a novel two-step keypoint adjustment method. Instead of matching new points in the original videos, our method effectively and efficiently adjusts the existing keypoints at the original scale. Finally, we refine the poses and structures using a rotation-averaging constrained global bundle adjustment (BA) technique, incorporating the adjusted keypoints. To enrich the resources available for SLAM or SfM studies, we provide a large-size (3840 × 2160) outdoor video dataset with millimeter-level-accuracy ground control points, which supplements the current relatively low-resolution video datasets. Experiments demonstrate that, compared with other SLAM or SfM methods, our method achieves an average efficiency improvement of 100% on our collected dataset and 45% on the EuRoc dataset. Our method also demonstrates superior localization accuracy when compared with state-of-the-art SLAM or SfM methods.

Controllable Preparation and Sodium Storage Properties of Sb2Te3–Te Heterojunction

Antimony-based materials possess high theoretical capacities and suitable potential, which could be promising anode materials for sodium-ion batteries (SIB). However, poor stabilities and sluggish kinetics are drawbacks. Building heterojunction is an ideal method to solve these issues. Its unique structure develops internal electric fields spontaneously to boost the charge transport and relieve stress. Nevertheless, the controllable preparation of face-to-face (2D) heterojunctions is still hard-pressed. Herein, Sb2Te3–Te nanoheterojunctions, which consist of two-dimensional Sb2Te3 nanoblades attached to a one-dimensional Te nanorod, are fabricated through a two-step solvothermal method. Among that, the density of nanoblades is adjustable through the engineering feed ratio. When employed as anodes for SIBs, Sb2Te3–Te nanoheterojunctions display a reversible capacity of 463.2[Formula: see text]mAh[Formula: see text]g[Formula: see text] at 100[Formula: see text]mA[Formula: see text]g[Formula: see text]. Even a capacity of 305.5[Formula: see text]mAh[Formula: see text]g[Formula: see text] remains after 1000 cycles under a high current of 1.5[Formula: see text]A[Formula: see text]g[Formula: see text]. Moreover, the density functional theory (DFT) calculations also identify the high conductivity of heterojunction. This work offers an effective way to design the structures and properties of heterojunctions, further expanding their application range.

Simple two-step synthesis of Ag/ZnO nanoparticles with enhanced photocatalytic response

Abstract This study presents a simple two-step synthesis method for the fabrication of Ag/ZnO nanocomposites to improve the photocatalytic response of ZnO. The synthesis involves ZnO nanoparticles that were fabricated from the thermal decomposition of commercial zinc acetate. In order to produce Ag/ZnO nanoparticles in a simple two-step process, ZnO nanoparticles were mixed with Ag nanoparticle suspensions previously obtained by the laser ablation of solids in liquids technique at three different fluences. Structural characterization of ZnO powders revealed the presence of single phase wurtzite ZnO nanoparticles with crystal sizes of 20 nm. On the other hand, XRD patterns for a composite sample revealed the presence of signals associated to both ZnO and Ag suggesting that silver nanoparticles were attached to the ZnO particles surface. 
Optical characterization of the ZnO powders, carried out by UV-Vis spectroscopy, showed a strong absorption band centered at 380 nm, which is associated to excitonic transitions in ZnO nanoparticles, whilst absorption measurements of silver nanoparticles colloids revealed the presence of a strong band centered near 412 nm. This band shifts to shorter wavelengths with increasing fluence from 2.6 to 6.2 J/cm2, indicating changes in nanoparticles size. Photocatalytic degradation tests of methylene blue under UV irradiation were carried out using pure ZnO, Ag colloids and Ag/ZnO nanoparticles. After the first 30 minutes of irradiation, it was observed that the silver nanoparticles reached degradation percentages of 16, 22 and 29 % for samples synthesized at 2.6, 4.2 and 6.2 J/cm2, respectively. Meanwhile the ZnO sample reached a value of 13 % after 30 minutes. Regarding the Ag/ZnO composite sample, the percentage of degradation after 30 minutes was 36%, demonstrating a considerable enhanced photocatalytic activity as compared to ZnO. After 24h irradiation, Ag/ZnO degraded 95% of the methylene blue solution. It was observed that decorating ZnO with laser produced silver nanoparticles accelerates the photocatalytic response of ZnO by enhancing the activity at short times. 

Comparative analysis of a fractional co-infection model using nonstandard finite difference and two-step Lagrange polynomial methods

In this work, Caputo fractional model for co-dynamics of two-strains (Alpha and Delta variants) of SARS-CoV-2 and tuberculosis (TB) is formulated. We investigates the basic mathematical analysis, existence of unique solution, stability analysis, sensitivity analysis and simulations of the proposed model. In the basic mathematical analysis, it is proved that the model’s solutions are non-negative, bounded and locally asymptotically stable at disease free equilibrium (DFE) point. The existence of unique solution is proved by using Banach fixed point theorem (BFPT). Stability analysis is carried out by employing Hyers–Ulam stability criteria. Sensitivity analysis is performed to assess the impact of the model parameters on the general dynamics of the model by implementing partial rank correlation coefficient (PRCC) technique. Simulations of the proposed model obtained from non-standard finite difference scheme (NSFDs) are compared with the simulations obtained from two-step Lagrange polynomial method (TLPM). It is concluded that NSFDs gives more accurate and realistic results than TLPM. To assess some control measures necessary for reducing the co-spread of both diseases, comparative simulations are carried out for the infected classes. Also, numerical assessments showed that preventive efforts against SARS-CoV-2 variants could results in the reduction of TB prevalence and the co-infection of both diseases.

Multifunctional composite flexible films of hydroxypropyl cellulose and silver nanowires

Flexible wearable devices have aroused attentions since the booming flexible electronic technologies, as well as the requirements for improved comfortableness and real-time monitoring for complex motion state of human body. Developing a flexible integrated wearable device with multi functions provides a promising route for next-generation wearable devices. Meanwhile, transparency and biocompatibility are also considered a lot. Herein, hydroxypropyl cellulose/silver nanowires (HPC/AgNWs) flexible composite films were fabricated with a facile two-step method. The fabricated composite films exhibited sufficient transparency and mechanical strength. More importantly, the HPC/AgNWs composite films afforded good motion sensing performances with current sensitivity as high as 350 %. It can accurately identify different bending angles and frequencies, and remained stable for more than 1000 bending cycles. Apart from being employed as motion sensors, the fabricated HPC/AgNWs could be also used for electrical heating and electromagnetic shielding. The films could be heated to more than 60°C at 3.0 V in 57 seconds, and the electromagnetic shielding efficiency reached more than 99.9 %. This study contributed a feasible strategy for the preparation of multifunctional flexible films which are expected to be further applicated in the field of wearable devices.

Accurate kinematic calibration of a six-DoF serial robot by using hybrid models with reduced dimension and minimized linearization errors

Accurate kinematic calibration of a six-DoF serial robot by using hybrid models with reduced dimension and minimized linearization errors

The Effect of Surfactant on the Stability of Inorganic Salt Hydrated Phase Change Material Containing Graphene Nanoplatelet: An Experimental Investigation

The use of nano phase change material (PCM) as a heat transfer agent has spread and expanded as its thermal conductivity is higher than the base PCM, so its use has been increased in PVT systems. In this study, inorganic salt hydrated PCM was used as a base material and Graphene nanoplatelet (GNP) as an additive to improve the thermal conductivity of the resulted nano-PCM and its stability was studied using Cetyl Trimethyl Ammonium Bromide (CTAB) surfactants. The main objective of the present study was to investigate the effect of surfactant on the stability of different GNP concentration in CaCl2.6H2O PCM. The nano-PCM has been prepared using two-step method. The stability of nano-PCM depends on the surfactant used to slow the sedimentation of nanoparticles in the base PCM. The sedimentation process significantly reduces the thermal conductivity of nano-PCM and thus reduces heat transfer. The study results indicated that the employment of surfactant significantly affected the stability of nanoparticles added in the base PCM. The stability test ascertained the effectiveness of the surfactant applied in phase change material. With successive addition of surfactant, the stability of GNP in PCM was further enhanced to +49.3 mV of Zeta potential value.

Effects of cell parameters on accurate calculation of activation dose after DT explosion for local hot spots in laser-driven ICF facilities

Instruments placed in the target chamber will be highly activated after DT explosion in laser-driven ICF experiments, especially for the part near the chamber center. Operations near those local hot spots are the main concern for radiation protection due to its high contribution to the occupation exposure dose, therefore it becomes very important to calculate the dose during the operating process accurately. Cell-based rigorous two-step (R2S) method has been introduced to deal with the activated objects with highly heterogeneous distribution, and the effects of cell size, materials as well as radiation source have also been specified to improve the accuracy of simulations. Results for a typical model sample show that with a given distribution of radiation source, cell size in the simulations placed a significant influence on the accuracy of the radiation field. A cell size of 50 cm for a 100 cm cone-shaped sample will lead to the inaccuracy of the radiation field as large as an order in magnitude within the location 50 cm from the surface of the sample. While for the same sample model, cell size should be limited to smaller than 2 cm to ensure an accuracy lower than ±10 %. In addition, the effects of the material and source energy on the calculation accuracy for the radiation field could be neglected if the cell size is limited to smaller than 5 cm. Furthermore, the influence of cell size increased as the distance from the sample surface decreased, which indicates that appropriate cell size must be chosen to ensure the accuracy of dose estimation, especially for surface contact operations. Besides, a significant difference between the effective dose and skin-equivalent dose has been observed for the typical mode used in the calculations.

Simultaneous measurement of thickness and group refractive index in birefringent crystals

Abstract In order to measure the group refractive index and thickness of birefringent crystals simultaneously, a method based on spectral-domain interferometry is proposed. The optical path of each reflection layer of birefringent crystal is converted into spectral interference fringe of corresponding frequency by the principle of spectral-domain interferometry, and the accurate optical path calculation is realized by fast Fourier transform and Hanning-windowed energy centrobaric method. A two-step measurement method was designed to measure the crystal thickness and group refractive index of ordinary(o) and extraordinary(e) light synchronously by comparing the changes of the optical path before and after the insertion of the sample. The comparison between experimental and theoretical results of LiNbO3 crystals shows that the accuracy of the thickness measured by this system is better than 1μm and the relative error of the group refractive index is better than 0.15%. The measurement method is simple to implement and has high precision, which is of practical significance for realizing the rapid and high-precision measurement of optical parameters of birefringent crystals.

MOF-derived multi-"hotspot" 3D Au/MOF-808 (Zr) nanostructures as SERS substrates for the ultrasensitive determination of thiram.

Aconvenient self-assembly methodis proposed for synthesis of 3D Au/MOF-808 (Zr) composite nanostructures with a cerium metal-organic framework loaded with gold nanoparticles. We combine adsorption properties of MOF materials with surface plasmon resonance of noble metals to construct hotspot-dense 3D Au/MOF-808 (Zr) SERS substrates, by using a two-step method of solvothermal and reduction reactions. The results show that optimal SERS substrates are obtained from a volume ratio of gold nanoparticles to MOF-808 (Zr) solution of 4:1 and a self-assembly time of 2h. Rhodamine 6G (R6G) is used as a molecular probe to characterize and analyze SERS properties of substrates of 3D Au/MOF-808 (Zr) prepared under the optimal process conditions, where the substrates are capable to detect R6G concentrations down to 10-10 M with a relative standard deviation of 8.81%. Finally, we applied the SERS substrates of 3D Au/MOF-808 (Zr) to the detection of pesticide thiram, and establish a quantitative determination method. 3D Au/MOF-808 (Zr) provides a sensitive detection of thiram in lake water by SERS with a detection limit of 1.49 × 10-9 M. Application tests show that a SERS enhancement factor of the MOF-based SERS substrates for the detection of thiram can be significantly increased to 5.91 × 105. Thus, the above results indicate that such substrate has high sensitivity, good adsorption, homogeneity, and reproducibility, which can be extended for sensitive detection of pesticide residues in food and environment.

Two-step synthesis of coconut shell biochar-based ternary composite to efficiently remove organic pollutants by photocatalytic degradation

Designing environmentally friendly, low cost and efficient photocatalysts is vitally important for degradation of organic pollutants. Herein, a ternary composite-ZnO/ACSC@TiO2, constituted by activated coconut shell derived biochar (ACSC), TiO2 and ZnO, was successfully synthesized by two-step hydrothermal method. It demonstrated that TiO2 could be uniformly wrapped on ACSC surface during first step to form core-shell structures (ACSC@TiO2). It was beneficial not only to enhance adsorption capacity for organic pollutants and absorption ability for light, but also to form C-doped TiO2 with a relatively narrow bandgap to expand light absorption of TiO2 from UV to visible light. Subsequently, ZnO was introduced through second step to generate type-II heterojunctions with ACSC@TiO2, which further reduced bandgap value of the ternary photocatalyst to promote photogenerated carrier generation and efficiently diminished recombination of e--h+ pairs. As expected, the optimal prepared catalyst with 10 wt% of ZnO (10%ZnO/ACSC@TiO2) exhibited excellent adsorptive and photocatalytic abilities for removal of tetracycline (TC) and Rhodamine B (RhB) with different initial concentrations. Particularly, its total removal efficiency for TC and RhB was 97.6% and 99.4%, respectively under 300 W xenon lamp irradiation (25 mg/L of organic pollutants, 1.0 g/L catalyst and natural pH in 60 min). Investigations on catalytic mechanism and degradation pathways proved that 10%ZnO/ACSC@TiO2 could remove RhB and TC by deep degradation. Its enhanced synergy of adsorption and photocatalysis could efficiently accelerate mineralization rates of RhB and TC. This biomass derived biochar-based ternary composite as photocatalyst with optimized energy band structures and microstructures would have good industrial application potential.

Guanidine carbonate modified TiO2/Perovskite interface for efficient and stable planar perovskite solar cells

The rational design and modification of the buried interface are essential and challenging for high-performance perovskite solar cells (PSCs). TiO2 is a simple and readily available electron transport layer material, but its surface defects and poor interfacial contact with perovskite layers hinder its widespread application. Here, we propose an effective TiO2/perovskite interface modification strategy by introducing simple guanidine carbonate (GuaCO3) onto the surface of TiO2. Guanidine carbonate can improve the interfacial contact between TiO2 and perovskite, reduce non-radiative recombination, and enhance carrier extraction. Moreover, the PbI2 film grown on the TiO2/GuaCO3 substrate tended to become porous during the preparation of perovskite films by the traditional two-step method, which facilitated the complete reaction of organic ammonium salts with PbI2 and promoted the growth of high-quality perovskite films. The experimental results indicate that GuaCO3 can passivate the interfacial defects of TiO2/perovskite, as well as reduce the accumulation of interfacial charges. The device modified with GuaCO3 achieved a power conversion efficiency (PCE) of 23.39 %, which is significantly higher than that of the control device (21.73 %). After storage in an ambient environment at room temperature for 600 h, the unencapsulated device modified with GuaCO3 retained 78 % of its initial efficiency, while the control device retained only 57 % of its initial efficiency. These results indicate that interfacial modification with GuaCO3 is an effective strategy for improving the performance of PSCs.

A two-step electrochemical method for separating Mg(OH)2 and CaCO3: Application to RO reject and polluted groundwater

The process of removing Ca2+ and Mg2+ ions typically results in the co-precipitation of Ca2+ and Mg2+ along with other salt waste. To improve water treatment efficiency towards a zero-waste goal, it is crucial to separate Ca2+ and Mg2+, and recover them in their purified form. This study proposes a two-step electrochemical approach that separately recovers Ca2+ as CaCO3 and Mg2+ as Mg(OH)2. The first step uses an undivided cell with 3D electrodes and controlled flow directions to selectively precipitate CaCO3 on the electrode, keeping the cell removal efficiency. The second step employs a two-compartment cell with a cationic exchange membrane to recover Mg(OH)2. This approach was evaluated on RO reject water with high Ca2+ to Mg2+ ratio and industrial effluent-polluted groundwater with a low ratio. Treatment of domestic RO reject water using undivided cell specifically recovered 64% of CaCO3, although the low conductivity of the RO reject water limited further Mg2+ recovery. Conversely, treating industrial effluent-polluted groundwater with this two-step process successfully recovered 80% of CaCO3 and 94% of Mg(OH)2. SEM, EDAX, and XRD analysis confirmed the quality of the recovered products.

Design of CuS composite carbon-based Ni Al-LDH multifunctional phase change composite with electromagnetic shielding performance and heat storage capacity

CuS-based composites are widely used in the fields related to photothermal energy storage and electromagnetic shielding and are excellent candidates for composites with phase change materials. To meet the requirements of micro-integration and electromagnetic resistance of electronic products and optimize the thermal management of electronic products, it is necessary to prepare new flexible composite phase change materials. In this paper, through the design of MPC@Ni Al-LDH/CuS double-layer structure, two-step vacuum filtration method is used, and the highly conductive materials CuS and MPC are introduced into the manufacture of PCM films. With the help of Ni Al-LDH, flame retardancy is introduced. The electromagnetic wave absorption performance is enhanced, and the existence of nano-cellulose (CNF) makes the film have excellent mechanical properties. Ni Al-LDH/MPC and CuS substrates with stable and high mechanical properties are prepared by ultrasonic treatment. According to scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC) and thermogravimetry (TG) characterizations, PEG successfully entered the MPC/CuS skeleton by vacuum filtration, and flexible phase change composite bilayers (MLPC) were obtained. Due to the synergistic effect of structure and components, the obtained composite film has many different excellent functions. Specifically, when MPC@Ni Al-LDH is 15 wt%, the phase transition enthalpy, thermal conductivity, electromagnetic shielding, and electrical conductivity are 146.8 J/g, 1.07 W/m·K, 38.8 dB and 126.4 S/m, respectively. The 3600 s infrared temperature measurement results show that the sample has stable thermal properties. Due to the presence of CuS, when MPC@Ni Al-LDH is 5 wt%, its absorbance can be kept at 1.51 L/(g·cm), and its photothermal conversion efficiency can reach 90.6 %. The MPC/CuS structure in the composite film provides many heat transfer channels, which reduces the phonon scattering in the heat transfer process and significantly increases thermal conductivity. Therefore, this multifunctional flexible phase change film can be used in photothermal conversion devices and for thermal management of electronic equipment, and it has broad application prospects in wearable equipment design due to its excellent electromagnetic shielding ability and infrared thermal stealth ability.

Critical COVID-19, Victivallaceae abundance, and celiac disease: A mediation Mendelian randomization study.

Celiac disease exhibits a higher prevalence among patients with coronavirus disease 2019. However, the potential influence of COVID-19 on celiac disease remains uncertain. Considering the significant association between gut microbiota alterations, COVID-19 and celiac disease, the two-step Mendelian randomization method was employed to investigate the genetic causality between COVID-19 and celiac disease, with gut microbiota as the potential mediators. We employed the genome-wide association study to select genetic instrumental variables associated with the exposure. Subsequently, these variables were utilized to evaluate the impact of COVID-19 on the risk of celiac disease and its potential influence on gut microbiota. Employing a two-step Mendelian randomization approach enabled the examination of potential causal relationships, encompassing: 1) the effects of COVID-19 infection, hospitalized COVID-19 and critical COVID-19 on the risk of celiac disease; 2) the influence of gut microbiota on celiac disease; and 3) the mediating impact of the gut microbiota between COVID-19 and the risk of celiac disease. Our findings revealed a significant association between critical COVID-19 and an elevated risk of celiac disease (inverse variance weighted [IVW]: P = 0.035). Furthermore, we observed an inverse correlation between critical COVID-19 and the abundance of Victivallaceae (IVW: P = 0.045). Notably, an increased Victivallaceae abundance exhibits a protective effect against the risk of celiac disease (IVW: P = 0.016). In conclusion, our analysis provides genetic evidence supporting the causal connection between critical COVID-19 and lower Victivallaceae abundance, thereby increasing the risk of celiac disease.