Large Agglomerates Research Articles

СТРУКТУРА И СВОЙСТВА ПОРОШКОВЫХ МАТЕРИАЛОВ НА ОСНОВЕ МЕХАНОСИНТЕЗИРОВАННЫХ МЕТАЛЛОМАТРИЧНЫХ КОМПОЗИТОВ Ni-TiC

The article considers the mechanochemical preparation of TiC-Ni composites in reaction mixtures of Ti-C-Ni powders and the formation of the structure of materials during their sintering under pressure. The synthesis was carried out in an AGO-2 planetary ball mill with a mixture processing time of 12 and 20 min; their subsequent sintering was performed at a temperature of 950 °C and a pressure of 130 MPa. The results of diffraction studies are presented for structural-phase transformations in mixtures of equimolar composition of titanium and carbon depending on the nickel content in the range of 50–70 wt.%. It is established that an increase in the Ni concentration leads to a decrease in the size of the formed TiCx crystallites from 29 ± 1 to 16 ± 1 nm. A high carbon content TiC0.88–0.98 carbide is formed in Ti-C-(50 and 60 %)Ni compositions and non-stoichiometric TiC0.62–0.78 at 70 % Ni. The microstructure of dispersion-strengthened grains of the nickel solid solution is formed during sintering of TiC/(50–60 %)Ni mechanocomposites. Titanium carbide inclusions have a spherical shape and a diameter of 60–100 nm. When sintering TiC/70%Ni, depleted titanium carbide has a grain boundary distribution with the formation of large (~400 nm) agglomerates. The microhardness of sintered materials is in the range of 850–900 HV.

Heterogeneous nucleation on defects in MoS2 nanostructures as a proxy for assessing active sites for hydrogen production

In the present work, we applied heterogeneous nucleation of gold nanoparticles to assess the density of defects on MoS2 nanostructures presenting different morphologies and surface areas. The use of L-cysteine resulted in the formation of flower-shaped MoS2 nanostructures with a diameter of about 300 nm and petals measuring around 30 nm. In contrast, when 3-mercaptopropionic acid was employed, it led to the formation of large agglomerates, here referred to as nanoclouds, with a diameter of approximately 500 nm. The nucleation of gold nanoparticles on defect sites of MoS2 suggested that MoS2 obtained from 3-mercaptopropionic acid has a higher content of active sites for hydrogen production compared to MoS2 obtained from L-cysteine.

Fabrication of Eucalyptus Oil-loaded Ciprofloxacin Hydrochloride Topical Films for Enhanced Treatment of Post-Operative Wound Infection

Background: The efficacious penetration of antimicrobials at infectious sites and the reduction of microbial resistance development are critical in controlling the effective treatment of post-operative wound infection. Methods: To create the enhanced antimicrobial topical films, a solvent casting method for ciprofloxacin hydrochloride (CiproHCl) loaded eucalyptus oil (EO) containing low molecular weight chitosan films was used. Nine batches of CiproHCl with varying chitosan and glycerol concentrations were prepared and tested. Additionally, optimised CiproHCl films with EO were created and tested. The antimicrobial activity of CiproHCl-loaded EO containing low molecular weight chitosan films against S. Aureus, E. Coli, and B. Subtilus was tested. Results: The FT-IR spectroscopy and DSC analysis revealed no interaction between the drug and any of the other excipients, and the drug remained amorphous in chitosan film. The SEM analysis revealed that the prepared CiproHCl-loaded EO-containing films had smooth surfaces and large agglomerates. In vitro drug release testing revealed that the EO-loaded films have a sustained release profile of up to 16 hours with a cumulative drug release of 96.83%. In an ex vivo drug permeation study, CiproHCl-loaded EO-containing films demonstrated 2.44 times more permeation flux than CiproHCl-alone films. After six months, the stability study revealed that the CiproHCl-loaded EO-loaded EO-containing film showed no significant change in drug release profile or folding endurance. Conclusion: This present study highlights the possible usage of CiproHCl-loaded EO containing low molecular weight chitosan films in enhanced post-operative wound treatment.

The formation of large aggregates by Brownian growth and the onset of a runaway process

In an experiment onboard a microgravity sounding rocket, we observed the growth of agglomerates consisting of silica spheres under well-defined conditions. After an initial short charge-induced growth phase, the charge-neutralized agglomerates grew due to Brownian-motion–induced collisions, first in an orderly fashion and thereafter, due to the temporal increase in particle concentration, in a runaway process. The latter is characterized by the detachment of large oligarch agglomerates. We modeled the growth using a mean-field approximation as well as a Monte Carlo technique.

Polyether Ketone Ketone (PEKK) matrix composites for material extrusion additive manufacturing

Despite the widespread use of fused filament fabrication (FFF) (an extrusion-based additive manufacturing process) to manufacture end-use parts for the aerospace industry, limited materials are available within this process that can be used for structural applications in the harsh space environment. Currently available high-performance polymers need to be improved by incorporating additives within the polymer matrix to achieve multi-functional properties. Additives such as graphene, graphene oxide, carbon nanotubes and boron carbide are known to improve mechanical and thermal properties and radiation shielding. This study aims to understand if these additives can be successfully incorporated into PEKK matrix to manufacture printable filaments for FFF. Graphene, graphene oxide (GO) and boron carbide (B4C) were compatibilised with PEKK matrix, and their mechanical, thermal and rheological properties were analysed and compared with commercially available carbon fibre and carbon nanotube-reinforced PEKK where appropriate. As rheological properties of the formulations confirmed that they were printable, filaments for FFF were then manufactured. Graphene–PEKK was the most printable filament followed by GO–PEKK while B4C–PEKK was not printable. TEM images of filament cross-section showed good dispersion of graphene and graphene oxide, while boron carbide formed large agglomerates; B4C also presented feeding issues due to its hardness which affected its printability. Dispersion of the additives was also confirmed by studying their X-ray diffraction (XRD) patterns, and chemical structures were assessed using FT-IR spectroscopy. Finally, parts were printed using selected composite filaments, and their porosity and surface roughness were compared with neat PEKK and commercial CNT-reinforced PEKK to develop an understanding of metrology and bulk material properties of the composites.

Parameters’ Influence on Electrospun Polystyrene-Grubbs’ Catalyst Composite Fibers Morphology

Electrospinning represents a simple, cost-effective technique that allows the production of continuous fibers, with diameters ranging from the micrometer to the nanometer scale. Mixing particles in the polymer feed solution could result in composite fibers, with various potential applications, depending on the particle filler. The influence of electrospinning parameters on the fiber morphology must be investigated to obtain undamaged fibers without large agglomerates. This research presents polystyrene (PS)-based electrospun composite fibers, containing the first- and the second-generation Grubbs’ catalyst (G1 and G2). Loading of both catalysts was 1[Formula: see text]wt.% in the composite fibers, and the influence of different solution flow rates on fiber diameter, shape and regularity was investigated. Applied flow rates were 5, 10, 15 and 20[Formula: see text]ml/h for both composites (PS-G1 and PS-G2). Software analysis of field emission scanning electron microscopy (FESEM) images has revealed that flow rate has a higher influence on the diameter increase in PS-G1 compared to PS-G2, due to a difference in electrostatic forces and polymer-catalyst interactions. In both composites, 10[Formula: see text]ml/h was the threshold for producing smooth and undamaged fibers, further enhanced in PS-G2, where large agglomerates were observed at 20[Formula: see text]ml/h. Furthermore, in both composites, fiber diameter distribution was significantly wider at higher flow rates, which is not a desirable feature in composites. The presented results demonstrated the synergy between different parameters that influence the formation and morphology of electrospun PS-based composites and could help in the future design and processing of continuous composite fibers.

Morphology of uranium oxides reduced from magnesium and sodium diuranate

Abstract Morphological analysis of uranium materials has proven to be a key signature for nuclear forensic purposes. This study examines the morphological changes to magnesium diuranate (MDU) and sodium diuranate (SDU) during reduction in a 10 % hydrogen atmosphere with and without steam present. Impurity concentrations of the materials were also examined pre and post reduction using energy dispersive X-ray spectroscopy combined with scanning electron microscopy (SEM-EDX). The structures of the MDU, SDU, and UO x samples were analyzed using powder X-ray diffraction (p-XRD). Using this method, UO x from MDU was found to be a mixture of UO2, U4O9, and MgU2O6 while UO x from SDU were combinations of UO2, U4O9, U3O8, and UO3. By SEM, the MDU and UO x from MDU had identical morphologies comprised of large agglomerates of rounded particles in an irregular pattern. SEM-EDX revealed pockets of high U and high Mg content distributed throughout the materials. The SDU and UO x from SDU had slightly different morphologies. The SDU consisted of massive agglomerates of platy sheets with rough surfaces. The UO x from SDU was comprised of massive agglomerates of acicular and sub-rounded particles that appeared slightly sintered. Backscatter images of SDU and related UO x materials showed sub-rounded dark spots indicating areas of high Na content, especially in UO x materials created in the presence of steam. SEM-EDX confirmed the presence of high sodium concentration spots in the SDU and UO x from SDU. Elemental compositions were found to not change between pre and post reduction of MDU and SDU indicating that reduction with or without steam does not affect Mg or Na concentrations. The identification of Mg and Na impurities using SEM analysis presents a readily accessible tool in nuclear material analysis with high Mg and Na impurities likely indicating processing via MDU or SDU, respectively. Machine learning using convolutional neural networks (CNNs) found that the MDU and SDU had unique morphologies compared to previous publications and that there are distinguishing features between materials created with and without steam.

3D Imaging of PEMFC Electrode Microstructure by Electron Tomography and 3D FIB/SEM

Scanning and transmission electron microscopies (SEM and TEM) are two imaging techniques widely used in the study of PEMFC electrode microstructure. They have played a significant role in the improvement of electrode components and the understanding of their main degradation mechanisms. However, the currently available description of the electrode microstructure does not allow yet to unambiguously identify the key microstructural factors that limit gas and proton transport within the electrode. These factors are crucial as they control the performance of the PEMFC, especially at high current density, and are therefore the subject of numerous studies, using either fine electrochemical measurements or modeling approaches.The objective of our work is to provide an improved description of the electrode microstructure by giving quantitative information on its porosity at different scales as well as on the ionomer distribution. For this purpose, we develop 3D characterization techniques applied to the PEMFC electrodes such as electron tomography and 3D FIB/SEM.The studied cathode electrode was prepared using TEC10E50E catalyst from Tanaka that is 50 wt % loading of Pt deposited on high-specific area carbon (HSAC), and Nafion D2020. The Pt loading of the electrode is 0.2 mgPtcm-2 and the ionomer/carbon ratio is 0.8.As a first step, electron tomography analyses were performed on the Pt/HSAC powder to determine the distribution of Pt nanoparticles (NPs) which can be located either on the carbon surface (outer NPs) or inside the carbon porosity (inner NPs)[1-3]. Our strategy is to record tilt image series by using two annular detectors: i) a high angle annular detector avoiding Pt NP diffraction contrast for the 3D image reconstruction of Pt NPs (without diffraction artifact) and ii) a lower angle annular detector that enhances carbon contrast for the 3D image reconstruction of the carbon phase. These two segmented images were then combined (Figure 1), allowing the calculation of the NP size histogram but also of the volume and the surface area of the two NP populations (inner and outer NPs).On the second step, the porosity of the electrode was analyzed by 3D FIB/SEM. A volume of around 10 X 10 x 5 μm3 was imaged with a cubic voxel size of 5 × 5 × 5 nm3. The solid phase (carbon, Pt NPs and ionomer) segmentation was based on a composite image created from two electron detectors (secondary and backscattered electrons) and using a machine learning software. Quantitative data such as the total porosity, the pore size distribution or the agglomerate size distribution of the solid phase were extracted from this volume. Figure 2a shows a 2D slice of this segmented volume where the solid phase is in black and the porosity in white.In order to analyze the electrode porosity with a higher spatial resolution, electron tomography experiment was also performed on a 150 nm thick slice of the electrode cut by ultramicrotomy after being embedded in an epoxy resin. The tilt image series were recorded with a pixel size of 0.5 nm and a field of view of 2 x 2 µm2. The 2D slice of the reconstructed volume (Figure 2b) shows that the largest solid agglomerates detected on the 3D FIB/SEM image can be identified as an agglomeration of numerous carbon particles. The challenge now is to quantify the porosity created between these carbon particles and to determine how many Pt NPs are located in these large agglomerates.Finally, the distribution of the ionomer was analyzed within the electrode similarly to [4]. For this analysis, a 150 nm slice of the electrode was cut by cryo-ultramicrotomy without embedding in epoxy resin as described in [5]. TEM images show that the ionomer is not homogeneously distributed on the surface of the entire carbon particles but is often observed in the concave surface created between the carbon particles (Figure 3). These observations suggest a ionomer distribution in agreement with the heterogeneous ionomer coating model proposed by Inoue et al. [6]. We also suggest that a part of the ionomer could be localized in the small pores located inside the large carbon agglomerates described in the previous paragraph. This could explain why the ionomer is so difficult to detect on TEM images. This work has been done in the frame of the FURTHER-FC project. This project has received funding from the Fuel Cells and Hydrogen 2 Joint Undertaking (now Clean Hydrogen Partnership) under Grant Agreement No 875025. This Joint Undertaking receives support from the European Union’s Horizon 2020 Research and Innovation program, Hydrogen Europe and Hydrogen Europe Research. Figure 1

(Invited) Unravelling the Core of Fuel Cell Performance: Engineering the Electrolyte (ionomer)/Catalyst Interface

The biggest challenge of the widespread implantation of the polymer electrolyte membrane fuel cells (PEMFCs) is the cost, primarily due to the use of platinum catalysts. The high intrinsic catalyst activity exhibited using a rotating disc electrode (RDE) is rarely realized in the membrane electrode assembly (MEA), which is the core of PEMFC, due to the difference on the electrolyte(ionomer)/catalyst interfaces. To translate the catalyst RDE performance into MEA, the design of an ideal ionomer/catalyst interface is proposed: a thin, conformal ionomer film covers the maximum surface of a Pt nanoparticle that simultaneously maximizes catalyst utilization, (i.e. high mass activity and electrochemical active surface area) and O2 diffusion (i.e. high current density performance) without compromising proton conduction. Building such an interface is a long-standing challenge due to no control of ionomer distribution over catalyst particle, resulting in large ionomer agglomerates and inhomogeneous ionomer coverage over the catalyst nanoparticle, consequently, poor fuel cell performance. In this work, this ionomer/catalyst interface has been constructed utilizing the electrostatic charge attraction between positively charged catalyst and negatively charged ionomer particles in a liquid and preserved into a solid catalyst layer. Consequently, this interface leads to the previously unachieved fuel cell performance on both the catalyst utilization (75% vs. 45%) and the rated/peak power density (Pt/C, 0.910/1.430 W/cm2 for H2/Air, Pt loading: 0.1 mgPt/cm2), matching that of Pt alloy catalysts. This work demonstrated the formation of the interface in the liquid phase (using ultra-small angle x-ray scattering in combination with cryo-TEM, isothermal‐titration‐calorimetry) and the preserved interface in the solid catalyst layer (using TEM) and estimated the effective coverage and thickness of the ionomer film (using the limiting current density, RDE and fuel cell performance).

TiO2-kaolinite composite photocatalyst for industrial organic waste decontamination

The industrially feasible TiO2-clay based photocatalysts are essential to overcome the practical barriers that are intrinsic to currently available clay-based photocatalysts. The present study demonstrates the fabrication of heterogeneous photocatalyst consisting of TiO2 and kaolinite (TKCP) that has shown improved catalytic activity and strength, ensuring industrial viable photocatalyst. TKCP is prepared via an economical method, employing mechanical compression and dehydroxylation, forming TiO2-clay hybrid matrix. Amount of clay primarily determines mechanical strength and photocatalytic efficiency of TKCP where TKCP with the lowest clay percentage results in a homogeneous matrix that consists of tiny TiO2 particles embedded clay sheet-like structure. The TiO2 particles embedded clay sheet-like structure is responsible for the high specific surface area and small pore size, increasing the active surface that is available for effective disintegration of organic contaminants. By increasing clay fraction in TKCP, a significant increase in surface defects can be observed due to large clay fragments and TiO2 agglomerates, which results in flexural strength and catalytic activity decrease. Methylene blue degradation on TKCP with the maximum TiO2 percentage results in the highest pseudo first-order rate constant of 0.58 h−1, exhibiting improved photocatalytic activity due to well-organized matrix and high specific surface area (82.79 m2 g−1). TKCP can be obtained in variable sizes and shapes that ensure dynamic wastewater treatment applications.

Spectrophotometric properties of CoPhyLab’s dust mixtures

ABSTRACT Objective: In the framework of the Cometary Physics Laboratory (CoPhyLab) and its sublimation experiments of cometary surface analogues under simulated space conditions, we characterize the properties of intimate mixtures of juniper charcoal and SiO2 chosen as a dust analogue (Lethuillier et al. 2022). We present the details of these investigations for the spectrophotometric properties of the samples. Methods: We measured these properties using a hyperspectral imager and a radio-goniometer. From the samples’ spectra, we evaluated reflectance ratios and spectral slopes. From the measured phase curves, we inverted a photometric model for all samples. Complementary characterizations were obtained using a pycnometer, a scanning electron microscope and an organic elemental analyser. Results: We report the first values for the apparent porosity, elemental composition, and VIS-NIR spectrophotometric properties for juniper charcoal, as well as for intimate mixtures of this charcoal with the SiO2. We find that the juniper charcoal drives the spectrophotometric properties of the intimate mixtures and that its strong absorbance is consistent with its elemental composition. We find that SiO2 particles form large and compact agglomerates in every mixture imaged with the electron microscope, and its spectrophotometric properties are affected by such features and their particle-size distribution. We compare our results to the current literature on comets and other small Solar system bodies and find that most of the characterized properties of the dust analogue are comparable to some extent with the spacecraft-visited cometary nuclei, as well as to Centaurs, Trojans, and the bluest TNOs.

Antifungal Activity and Molecular Mechanisms of Copper Nanoforms against Colletotrichum gloeosporioides

In this work, we have synthesized copper nanoforms (Cu NFs) using ascorbic acid as a reducing agent and polyvinylpyrrolidone as a stabilizer. Elemental characterization using EDS has shown the nanostructure to be of high purity and compare well with commercially sourced nanoforms. SEM images of both Cu NFs show some agglomeration. The in-house NFs had a better even distribution and size of the nanostructures. The XRD peaks represented a face-centered cubic structure of Cu2O. The commercially sourced Cu NFs were found to be a mixture of Cu and Cu2O. Both forms had a crystalline structure. Using these two types of Cu NFs, an antimicrobial study against Colletotrichum gloeosporioides, a devastating plant pathogen, showed the in-house Cu NFs to be most effective at inhibiting growth of the pathogen. Interestingly, at low concentrations, both Cu NFs increased fungal growth, although the mycelia appeared thin and less dense than in the control. SEM macrographs showed that the in-house Cu NFs inhibited the fungus by flattening the mycelia and busting some of them. In contrast, the mycelia were short and appeared clustered when exposed to commercial Cu NFs. The difference in effect was related to the size and/or oxidation state of the Cu NFs. Furthermore, the fungus produced a defense mechanism in response to the NFs. The fungus produced melanin, with the degree of melanization directly corresponding to the concentration of the Cu NFs. Localization of aggregated Cu NFs could be clearly observed outside of the model membranes. The large agglomerates may only contribute indirectly by a hit-and-bounce-off effect, while small structures may adhere to the membrane surface and/or internalize. Spatio-temporal membrane dynamics were captured in real time. The dominant dynamics culminated into large fluctuations. Some of the large fluctuations resulted in vesicular transformation. The major transformation was exo-bud/exo-cytosis, which may be a way to excrete the foreign object (Cu NFs).

Characterization and Evaluation of Heat-Moisture-Modified Black and Red Rice Starch: Physicochemical, Microstructural, and Functional Properties.

This study sought to evaluate starch from black and red rice modified by heat-moisture, investigating the extraction yield, starch and amylose content, color, and phenolic compounds. The water and oil absorption capacity, whole milk and zero lactose absorption index, syneresis index, and texture were also analyzed. Microstructural analysis included Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The heat-moisture treatment (HMT) reduced the extraction yield and the starch and amylose content, with native black rice starch having the highest values for these parameters. The modification also affected the color and phenolic compounds of the starch, making it darker and changing its appearance. The modification improved the absorption of water, oil, and milk, reducing syneresis and increasing stability during storage. The starch surface was altered, especially for modified black rice starch, with larger agglomerates. The type of starch also changed from A to Vh, with lower relative crystallinity. The textural properties of modified red rice starch were also significantly altered. The HMT proved to be a viable and economical option to modify the analyzed parameters, influencing the texture and physicochemical properties of pigmented rice starch, expanding its applications, and improving its stability during storage at temperatures above 100 °C.

Low-cost heterogeneous composite photocatalyst consisting of TiO2, kaolinite and MMT with improved mechanical strength and photocatalytic activity for industrial wastewater treatment

The industrially feasible TiO<sub>2</sub>-clay-based photocatalysts are essential to overcome practical barriers that are inherent to currently available TiO<sub>2</sub>-based photocatalysts. The current study demonstrates the fabrication of heterogeneous photocatalyst using TiO<sub>2</sub>, kaolinite, and montmorillonite (TKMCP), which has shown improved catalytic activity and mechanical strength, resulting in an industrially feasible photocatalyst. The TKMCP is prepared in a cost-effective manner using 60% TiO<sub>2</sub> and 40% clay with different kaolinite to MMT ratios (1:3 TKMCP1, 1:1 TKMCP2, and 3:1 TKMCP3) by employing mechanical compression and dehydroxylation. The clay ratio predominantly determines the TKMCP mechanical strength and photocatalytic efficiency, where the lowest MMT percentage results in a uniform matrix, in which TiO<sub>2</sub> particles are embedded on clay-sheets. The TKMCP surface became uniform when the MMT percentage is low, whereas a high MMT fraction results in a disordered catalytic surface due to large clay fragments and agglomerates. All three composites accounted for more than 85% of the degradation rate, exhibiting pseudo first order kinetics, resulting in high-rate constants, with the highest observed for TKMCP3, which is 1.55 h<sup>–1</sup>. The TKMCP3 accounts for the highest mechanical strength, which is 5.83 MPa, while the lowest is observed with TKMCP1, indicating that the TKMCP strength decreases significantly with high MMT fraction. TKMCP has several advantages, including easy fabrication, low cost, free of hazardous chemicals, high production capacity with minimal machinery/supervision, non-self-degradability, easy disposal, easy installation in pilot-scale reactors, compatibility with both batch and flow reactors, environmental, and user-friendliness. TKMCP can also be obtained in variable sizes and shapes that ensure dynamic wastewater treatment applications.

Electrostatic capture of viruses on cationic biopolymer membranes for intra-oral disease sampling

Naso- and oropharyngeal swabs are the Center for Disease Control and Prevention (CDC) -recommended disease sampling methods for respiratory viruses. The short swabbing time for sampling by these methods may lead to variability in test results. Further, these methods are mildly invasive and can cause discomfort, tearing or gag reflexes in tested individuals. If longer sampling time is coupled with lesser patient discomfort, test reliability and patient compliance can be improved. Towards this end, we developed cationic biopolymer membranes for the electrostatic capturing of viruses in the oral cavity. Here, chemically (EDC-NHS) crosslinked uncharged chitosan (CS) nanofiber membranes were conferred either with negative surface charge by anionic poly-aspartic acid (pAsp) coating or positive charge by cationic poly-L-lysine (PLL). Consistent with our preliminary findings of dynamic light scattering (DLS) size measurements showing large agglomerates of anionic virus-like particles (VLPs) and cationic PLL in solution, a 75% increase in VLP adsorption by PLL coated CS membranes was recorded by enzyme linked immunosorbent assay (ELISA), in comparison to untreated controls. It is envisaged that the electrostatic concentration of respiratory viruses on cationic membranes can be superior alternatives to traditional swabbing in the oral cavity.

Enhancement of integrated nano-sensor performance comprised of electrospun PANI/carbonaceous material fibers for phenolic detection in aqueous solutions

The detection of trace levels of organic residue in water samples is a key health issue. This manuscript describes the fabrication of integrated nano-sensors composed of electrospun microfibers consisting of a nanocomposite of carbonaceous materials (CNMs) containing polyaniline (PANI) and polycaprolactone (PCL) for phenolic detection in aqueous solutions. The morphology of the resulting microfiber composite was characterized by scanning electron microscopy. It revealed elongated fibers with a highly interconnected web-like pattern in the presence of reduced graphene oxide (rGO). Shorter microfibers were observed in the composite filled with multi-walled carbon nanotubes (MWCNTs), whereas large agglomerates were formed upon the incorporation of single-walled CNTs (SWCNTs) and graphene 300 (G300). Comparative analysis showed that the PANI/CNM sensors exhibited the best electrochemical properties, in particular in the presence of rGO and MWCNTs, where greater electrical conductivity was achieved, i.e., 4.33 × 10−3 and 7.22 × 10−4 S/cm, respectively, as compared to the PANI-PCL sensor (3.79 × 10−4 S/cm). All the PANI/CNM sensors exhibited high sensitivity. Notably, PANI/rGO was found to have a detection limit of 8.34 × 10−3 µM for aminophenol. All the sensors exhibited good selectivity in the presence of interference to detecting phenolic compounds in aqueous solutions, thus confirming their value for industrial applications.

Design and researching of biologically active polymeric hydrogel transdermal materials modified by humic acid

Biologically active polymer hydrogel transdermal materials based on gelatin, sodium alginate, modified by humic acids, were designed and researched. Literature review was carried out and it was proved that humic acids using is perspective for the functional effect on the biologically active polymer hydrogel transdermal properties. It has been found that effective processes for receiving biologically active polymer hydrogel transdermal materials based on gelatin, hydroxypropyl cellulose and sodium alginate can be carried out in different humic acids concentration while achieving an effective increase in hydrogel polymers structuring processes. It can be seen efficiently increasing biologically active polymeric hydrogel transdermal materials based on gelatin and sodium alginate conditional viscosity and the specific electrical conductivity with an increase of humic acids content: from 114 to 135 sec and from 2350 to 2850 mkS/cm, respectively. Humic acids modification in biologically active polymeric hydrogel transdermal materials based on gelatin and sodium alginate caused structure formation with high density, and resistance and with larger agglomerates in hydrogels. It was found that the gelatin-based biopolymer hydrogels modification by humic acids makes it possible to receive biologically active polymeric hydrogel transdermal materials with higher swelling degree. It is shown that the application of new biologically active polymeric hydrogel transdermal materials based on gelatin and sodium alginate modified by humic acids allows improving the skin moisture-lipid balance. From the initial values of 34-36% moisture and 8-10 skin fat, they increase to 58-66% and 52-60%. So, designed polymer hydrogel based on gelatin, sodium alginate, modified by humic acids, are transdermal materials with good properties.

Effect of Chemical Fertilizer with Compound Microbial Fertilizer on Soil Physical Properties and Soybean Yield

Compound microbial fertilizer is a new type of environmentally friendly slow-release fertilizer that can effectively improve the physical and chemical properties of the soil, significantly improve the ecological environment, and promote the sustainable development of agriculture. In this study, we conducted a field experiment to evaluate the impact of different applications of chemical fertilizer combined with composite microbial fertilizer on soil physical properties and soybean yields at Heshan Farm, Heilongjiang Province, China, during 2021–2022. Soybean varieties “Jinyuan 55” and “Keshan 1” were treated with three treatments implemented as follows: T1 (conventional fertilization), T2 (50% N fertilizer + compound microbial fertilizer), and T3 (0 N fertilizer + compound microbial fertilizer). Compared to conventional fertilization (T1 treatment), the application of composite microbial fertilizers (T2 and T3) resulted in a decrease in soil bulk density and an increase in porosity. Notably, we observed that moderate application of the composite microbial fertilizer (T3) led to a decrease in the volume fraction of clay particles and an increase in the volume fraction of sand particles. Furthermore, all treatments exhibited high content of agglomerates larger than 5 mm at 0–20 cm. The application of composite microbial fertilizers (T2 and T3) promoted the formation of large soil agglomerates and reduced the presence of micro-agglomerates smaller than 0.25 mm. In 2021–2022, The soybean yield increased by 13.02% in the T2 treatment compared with the T1 treatment and decreased by 9.34% in the T3 treatment. We concluded that the appropriate application of compound microbial fertilizer can help protect black soil, enhance the self-repair capability of black soil, and improve soybean quality in abnormal precipitation years. These results provide an actionable basis for constructing and developing green fertilizer systems for the soybean industry.

Influence of structural changes on gas transport properties of a cycled CaO/Ca(OH)2 powder bulk for thermochemical energy storage

Thermochemical energy storage using reversible gas-solid reactions has a great potential to evolve into a vital part of a future energy system. A major obstacle for technical application, however, is caused by insufficient gas transport within storage reactors leading to ineffective charging and discharging as well as lower storage densities. Although significant changes in the solid bulk structure are reported throughout the literature, the relevant material property – the bulk permeability – is rarely experimentally studied. In the presented study, the evolution of the gas permeability of a technical grade CaO/Ca(OH)2 powder bulk is studied experimentally. To this end, the pressure drop at ambient conditions is recorded before thermochemical cycling as well as after each dehydration respectively rehydration reaction. The pressure gradient and thereby the permeability is determined based on Darcy's law. The permeability of the fresh Ca(OH)2 bulk after compaction due to the gas flow is 1·10−13 m2. Due to restructuring during thermochemical cycling the permeability increases to 1.6…3.3·10−12 m2 for the cycled Ca(OH)2 bulk and 9.2·10−12 m2 to 2.4·10−11 m2 for the cycled CaO bulk. Further analysis of fresh and cycled samples shows a general increase in particle size and decrease in specific surface area as well as a reduction in reactivity due to agglomeration of the powder. Noticeable is the inhomogeneity of the cycled bulk with powder mixed with larger agglomerates at the top of the bulk and highly porous but seemingly homogeneous solid material at the bottom. Based on the experimental results, gas transport within the agglomerates is identified as a major limiting factor within thermochemical reactors. It is therefore proposed to consider cycled CaO/Ca(OH)2 bulks on a macro- and mesoscale (respectively bulk and agglomerate) simultaneously if transport properties – and their impact on effective reaction dynamics – are relevant.

Bubbling fluidized bed co-combustion and co-gasification of sewage sludge with agricultural residues with a focus on the fate of phosphorus

In this work, the fate of the ash-forming elements during bubbling fluidized bed combustion and gasification of P-rich sewage sludge (SS) and mixtures with either Si-K-rich wheat straw (WS) or K-Ca-rich sunflower husks (SH) were investigated. The focus of the study was assessing the feasibility of using fuel blends in fluidized bed systems and potential P recovery from the resulting ashes. The used fuels were pure SS and mixtures including 90 wt.% WS (WSS) and 85 wt.% SH (SHS). The analyzed operating conditions were combustion (930–960 °C, λ: 1.2–1.5) and gasification (780–810 °C, λ: 0.4–0.7) in a 5 kW bench-scale reactor. Residual ash and char fractions were collected from different parts of the 5 kW bubbling fluidized bed (bed, cyclone, filter) and analyzed by CHN, SEM/EDS, XRD, and ICP-AES.The conversion of the fuel mixtures achieved a steady state under the used process conditions except for the combustion of WSS, which led to the formation of large bed agglomerates with the bed material. The morphology of ash samples after combustion showed that SS fuel pellets mostly maintained their integrity during the experiment. In contrast, the ash and char particles from fuel mixtures were fragmented, and larger quantities were found in the cyclone, the filter, or on interior reactor surfaces. The fate of P was dominated by crystalline Ca-dominated whitlockites in all ash fractions, partially including K for the fuel mixtures SHS and WSS. 76–81 % of ingoing P was found in the bed residue after combustion and gasification of the SS-fuel. After conversion of the fuel mixtures SHS and WSS, the share was lower at 22–48 %, with larger shares of P in the entrained fractions (25–34 %). The quantity of identified crystalline compounds was lower after gasification than combustion, likely due to the limited interaction of ash-forming elements in the residual CHN matrix. Altogether, the results show that fuel mixtures of sewage sludge with agricultural residues could expand the fuel feedstock and enable P recovery. This may be used in the fuel and process design of upscaled fluidized bed processes or systems employing both combustion and gasification.