bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship between Photosynthetic CO2 Assimilation and Chlorophyll Fluorescence for Winter Wheat under Water Stress
Authors: Jia Qianlan , Liu Zhunqiao , Guo Chenhui , Wang Yakai , Yang Jingjing , Yu Qiang , Wang Jing , Zheng Fenli , Lu Xiaoliang
Published: September 2023

Solar-induced chlorophyll fluorescence (SIF) has a high correlation with Gross Primary Production (GPP). However, studies focusing on the impact of drought on the SIF-GPP relationship have had mixed results at various scales, and the mechanisms controlling the dynamics between photosynthesis and fluorescence emission under water stress are not well understood. We developed a leaf-scale measurement system to perform concurrent measurements of active and passive fluorescence, and gas-exchange rates for winter wheat experiencing a one-month progressive drought. Our results confirmed that: (1) shifts in light energy allocation towards decreasing photochemistry (the quantum yields of photochemical quenching in PSII decreased from 0.42 to 0.21 under intermediate light conditions) and increasing fluorescence emissions (the quantum yields of fluorescence increased to 0.062 from 0.024) as drought progressed enhance the degree of nonlinearity of the SIF-GPP relationship, and (2) SIF alone has a limited capacity to track changes in the photosynthetic status of plants under drought conditions. However, by incorporating the water stress factor into a SIF-based mechanistic photosynthesis model, we show that drought-induced variations in a variety of key photosynthetic parameters, including stomatal conductance and photosynthetic CO2 assimilation, can be accurately estimated using measurements of SIF, photosynthetically active radiation, air temperature, and soil moisture as inputs. Our findings provide the experimental and theoretical foundations necessary for employing SIF mechanistically to estimate plant photosynthetic activity during periods of drought stress.
Genome and Transcriptome Analyses of Genes Involved in Ascorbate Biosynthesis in Pepper Indicate Key Genes Related to Fruit Development, Stresses, and Phytohormone Exposures
Authors: Aguiar Évelyn Silva de , Dias Abigailde Nascimento , Sousa Raquel Mendes , Germano Thais Andrade , de Sousa Renato Oliveira , Miranda Rafael de Souza , Costa José Hélio , dos Santos Clesivan Pereira
Published: September 2023

Pepper (Capsicum annuum L.) is a vegetable consumed worldwide, primarily used for vitamin C uptake and condiment purposes. Ascorbate (Asc) is a multifunctional metabolite, acting as an antioxidant and enzymatic cofactor involved in multiple cellular processes. Nevertheless, there is no evidence about the contribution of biosynthesis pathways and regulatory mechanisms responsible for Asc reserves in pepper plants. Here, we present a genome- and transcriptome-wide investigation of genes responsible for Asc biosynthesis in pepper during fruit development, stresses, and phytohormone exposures. A total of 21 genes, scattered in ten of twelve pepper chromosomes were annotated. Gene expression analyses of nine transcriptomic experiments supported the primary role of the L-galactose pathway in the Asc-biosynthesizing process, given its constitutive, ubiquitous, and high expression profile observed in all studied conditions. However, genes from alternative pathways generally exhibited low expression or were unexpressed and appeared to play some secondary role under specific stress conditions and phytohormone treatments. Taken together, our findings provide a deeper spatio-temporal understanding of expression levels of genes involved in Asc biosynthesis, and they highlight GGP2, GME1 and 2, and GalLDH members from L-galactose pathway as promising candidates for future wet experimentation, addressing the attainment of increase in ascorbate content of peppers and other crops.
Effects of Different Water and Nitrogen Supply Modes on Peanut Growth and Water and Nitrogen Use Efficiency under Mulched Drip Irrigation in Xinjiang
Authors: Dong Jianshu , Xue Zhu , Shen Xiaojun , Yi Ruochen , Chen Junwei , Li Qiang , Hou Xianfei , Miao Haocui
Published: September 2023

The optimization of irrigation and fertilization indexes for peanuts with drip irrigation is urgently needed in Xinjiang. A field experiment was conducted during the 2021 peanut growing season at Urumqi, Xinjiang, in Northwestern China, to evaluate the effects of different water and nitrogen treatments on the growth, yield, and water and nitrogen utilization of peanuts. In field experiments, we set up three irrigation levels (irrigation water quotas of 22.5, 30, and 37.5 mm, respectively, for W1, W2, and W3), two nitrogen application levels (77.5 and 110 kg·ha−1, recorded as N1 and N2), and a control treatment (W2N0) that did not include the application of nitrogen. The results showed that nitrogen application enhanced the growth, physiological indexes, yield, and water use efficiency of the W1, W2, and W3 treatments when the irrigation volume remained the same. In comparison with no nitrogen application (W2N0), the peanut growth, physiological indexes, yield, and water use efficiency improved with increasing irrigation amounts in the N1 and N2 treatments. With an increase in the irrigation volume, the water use efficiency grew; the W3N2 treatment had the highest water use efficiency, which was 1.32 kg·m−3. The total water consumption and reproductive-stage water consumption of the peanuts in all treatments increased with the irrigation volume, and a high yield was achieved at 402.57 mm, which was 5.2974 Mg·ha−1. In the W1, W2, and W3 treatments, the nitrogen partial factor productivity significantly decreased as the nitrogen application increased, with the nitrogen partial factor productivity in the W3N1 treatment being the highest, at 60.61 kg·kg−1. A comprehensive evaluation based on principal component analysis assigned W3N2 the higher score. These findings suggest that irrigation water quotas of 37.5 mm should be coupled with 110 kg·ha−1 nitrogen applications for peanuts using drip irrigation in mulch film in Xinjiang.
Sustainable Collagen Composites with Graphene Oxide for Bending Resistive Sensing
Authors: Andonegi Mireia , Correia Daniela M. , Pereira Nelson , Costa Carlos M. , Lanceros-Mendez Senentxu , de la Caba Koro , Guerrero Pedro
Published: September 2023

This work reports on the development of collagen films with graphene oxide nanoparticles (GO NPs), aiming toward the development of a new generation of functional sustainable sensors. For this purpose, different GO NP contents up to 3 wt % were incorporated into a collagen matrix, and morphological, thermal, mechanical and electrical properties were evaluated. Independently of the GO NP content, all films display an increase in thermal stability as a result of the increase in the structural order of collagen, as revealed by XRD analysis. Further, the inclusion of GO NPs into collagen promotes an increase in the intensity of oxygen characteristic absorption bands in FTIR spectra, due to the abundant oxygen-containing functional groups, which lead to an increase in the hydrophilic character of the surface. GO NPs also influence the mechanical properties of the composites, increasing the tensile strength from 33.2 ± 2.4 MPa (collagen) to 44.1 ± 1.0 MPa (collagen with 3 wt % GO NPs). Finally, the electrical conductivity also increases slightly with GO NP content, allowing the development of resistive bending sensors.
Role of Bio-Based and Fossil-Based Reactive Diluents in Epoxy Coatings with Amine and Phenalkamine Crosslinker
Authors: Samyn Pieter , Bosmans Joey , Cosemans Patrick
Published: September 2023

The properties of epoxy can be adapted depending on the selection of bio-based diluents and crosslinkers to balance the appropriate viscosity for processing and the resulting mechanical properties for coating applications. This work presents a comprehensive study on the structure–property relationships for epoxy coatings with various diluents of mono-, di-, and bio-based trifunctional glycidyl ethers or bio-based epoxidized soybean oil added in appropriate concentration ranges, in combination with a traditional fossil-based amine or bio-based phenalkamine crosslinker. The viscosity of epoxy resins was already reduced for diluents with simple linear molecular configurations at low concentrations, while higher concentrations of more complex multifunctional diluents were needed for a similar viscosity reduction. The curing kinetics were evaluated through the fitting of data from differential scanning calorimetry to an Arrhenius equation, yielding the lowest activation energies for difunctional diluents in parallel with a balance between viscosity and reactivity. While the variations in curing kinetics with a change in diluent were minor, the phenalkamine crosslinkers resulted in a stronger decrease in activation energy. For cured epoxy resins, the glass transition temperature was determined as an intrinsic parameter that was further related to the mechanical coating performance. Considerable effects of the diluents on coating properties were investigated, mostly showing a reduction in abrasive wear for trifunctional diluents in parallel with the variations in hardness and ductility. The high hydrophobicity for coatings with diluents remained after wear and provided good protection. In conclusion, the coating performance could be related to the intrinsic mechanical properties independently of the fossil- or bio-based origin of diluents and crosslinkers, while additional lubricating properties are presented for vegetable oil diluents.
Analysis of Thermal Aging Influence on Selected Physical and Mechanical Characteristics of Polyaddition and Polycondensation Poly(dimethylsiloxane)
Authors: Chmielnicka Ewelina , Szymiczek Małgorzata , Sarraj Sara , Jurczyk Sebastian
Published: September 2023

The aim of the study was to determine the effect of accelerated thermal aging on the properties of selected poly(dimethylsiloxanes) (PDMS) differing in viscosity and hardness. This was related to the potential application for specialist casting molds with complex geometry. Four polyaddition silicones and two polycondensation ones were selected. As part of the work, tensile strength, hardness, density, roughness, and Dynamic Mechanical Analysis (DMA) and Fourier Transform Infrared Spectroscopy (FTIR) were tested, which allowed us to determine the degree of degradation of the analyzed materials subjected to thermal aging at a temperature of 150 ± 2 °C. The aging temperature was conditioned by the parameters of the materials that can be cast into molds made of poly(dimethylsiloxanes) e.g., with polymer resins, for which the exothermic peak ranges from 100 to 200 °C depending on the volume. It was observed that the initial Shore A hardness value affects parameters such as tensile strength or the amount of value change (its increase or decrease) after thermal aging. It can also be concluded that for polyaddition PDMS, the viscosity of the material has an effect on the size of the relative elongation value after thermal aging.
Review of Additively Manufactured Polymeric Metamaterials: Design, Fabrication, Testing and Modeling
Authors: Almesmari Abdulla , Baghous Nareg , Ejeh Chukwugozie J. , Barsoum Imad , Abu Al-Rub Rashid K.
Published: September 2023

Metamaterials are architected cellular materials, also known as lattice materials, that are inspired by nature or human engineering intuition, and provide multifunctional attributes that cannot be achieved by conventional polymeric materials and composites. There has been an increasing interest in the design, fabrication, and testing of polymeric metamaterials due to the recent advances in digital design methods, additive manufacturing techniques, and machine learning algorithms. To this end, the present review assembles a collection of recent research on the design, fabrication and testing of polymeric metamaterials, and it can act as a reference for future engineering applications as it categorizes the mechanical properties of existing polymeric metamaterials from literature. The research within this study reveals there is a need to develop more expedient and straightforward methods for designing metamaterials, similar to the implicitly created TPMS lattices. Additionally, more research on polymeric metamaterials under more complex loading scenarios is required to better understand their behavior. Using the right machine learning algorithms in the additive manufacturing process of metamaterials can alleviate many of the current difficulties, enabling more precise and effective production with product quality.
Thermoplastic Electromagnetic Shielding Materials from the Integral Recycling of Waste from Electronic Equipment
Authors: Aradoaei Mihaela , Ciobanu Romeo C. , Schreiner Cristina , Ursan Andrei George , Hitruc Elena Gabriela , Aflori Magdalena
Published: September 2023

The European Green Deal’s goals are anticipated to be fulfilled in large part thanks to the New Circular Economy Action Plan. It is believed that recycling materials will have a significant positive impact on the environment, particularly in terms of reducing greenhouse gas emissions and the impacts this will have on preventing climate change. Due to the complexity of the issue and its significant practical ramifications, the activity of Waste Electrical and Electronic Equipment (WEEE) collection networks is a subject of interest for researchers and managers, in accordance with the principles that recent laws have addressed in a large number of industrialized countries. The goal of this paper is to characterize and obtain composite materials using an injection process with a matrix of LDPE, PP, and HDPE, with up to a 10% addition of nonmetallic powders from PCBs and electronic parts from an integrated process of WEEE recycling. The composites present relevant thermal, electrical, and mechanical properties. Such composite materials, due to their relevant dielectric properties, may be further tested for applications in electromagnetic shielding at frequencies above 1 kHz, or for electromagnetic interference/electromagnetic compatibility (EMI/EMC and ESD) applications at lower frequencies due to their superior dielectric loss factor values, associated with relevant behaviors around exploitation temperatures, mainly for the electric, electronic, or automotive industries.
Study on Capillary Water Absorption of Waterborne-Polyurethane-Modified Recycled Coarse Aggregate Concrete
Authors: Fan Guoxi , Xiang Wantong , Yang Jing , Yang Shutong , Xiang Chunping
Published: September 2023

The reuse of construction and demolition waste as a substitute for natural coarse aggregate in the production of recycled concrete has been widely used. In order to study the capillary water absorption performance of waterborne-polyurethane-modified recycled aggregate concrete (WPUMRC), the effects of different curing systems, polymer-cement ratios, and waterborne polyurethane addition methods on the cumulative water absorption and the rate of capillary water absorption of WPUMRC were analyzed, and through MIP tests, the micro modification mechanism of waterborne polyurethane in recycled concrete was analyzed. The results indicate that the optimal curing system for both DC (waterborne polyurethane is added separately from water) and HC (waterborne polyurethane is mixed with some effective water and then added) is the 14 d standard curing—14 d indoor natural drying curing system. Waterborne polyurethane can fill the pores and micro-cracks inside WPUMRC or interweave with the hydration products of cement to form a spatial network structure, reducing the porosity, and thereby improving the capillary water absorption performance of WPUMRC. Based on the MIP test results, the grey correlation method was used to establish the relationship between capillary water absorption and the pore structure of WPUMRC under the optimal curing system. In addition, the prediction model of capillary water absorption in recycled concrete was established according to the test results, which can be used to predict WPUMRC’s capillary water absorption performance.
Understanding the Behavior of Sodium Polyacrylate in Suspensions of Silica and Monovalent Salts
Authors: Quezada Gonzalo R. , Retamal Francisco , Jeldres Matías , Jeldres Ricardo I.
Published: September 2023

This study investigated the interaction of monovalent cations with different sizes on quartz surfaces and the rheological impact that this causes in concentrated suspensions when subjected to the action of a rheological modifier, in this case, sodium polyacrylate (NaPA). Yield stress was determined using a rheometer with a vane-in-cup configuration to establish the relationship between shear stress and strain. Experiments were carried out in LiCl, NaCl, KCl, and CsCl solutions. The results show that the yield stress increases following the order Li < Na < K < Cs in the absence of PAA. However, the addition of NaPA significantly reduced the yield stress in all cases. This reduction was more noticeable in the LiCl and NaCl solutions than in the KCl and CsCl solutions, suggesting a more pronounced effect of PA in maker salts. We conducted molecular dynamics simulations to understand how PA interacts with dissolved salts on the quartz surface. Our results showed that Li had the highest adsorption, followed by Na, K, and Cs. As the salt concentration increased, so did the adsorption. We validated these simulation results with rheological experiments, which helped us understand the observed differences. The molecular interactions indicate that, in the lithium system, cationic bridges and the synergy between hydrogen bridges and hydrophobic bridges predominate mainly. This tendency decreases as the type of cation is changed due to the decrease in the electrical density of the cation in the following order: Li < Na < K < Cs. This reduces bridging with the quartz surface and, therefore, directly impacts the system’s rheological properties.
Reliability Analysis of HHV Prediction Models for Organic Materials Using Bond Dissociation Energies
Authors: Tao Junjun , Pan Longwei , Yao Jiajie , Liu Longfei , Chen Qiang
Published: September 2023

The purpose of this study is to analyze the reliability of predictive models for higher heating values related to organic materials. A theoretical model was developed, which utilizes bond dissociation energies (BDEs) to establish correlations between elemental composition and calorific values. Our analysis indicates that the energy contribution of one mole of hydrogen atoms is approximately equal to −144.4 kJ mol−1. Further investigation reveals significant variations in the bond dissociation energies of carbon atoms within organic compounds, resulting in a range of energy outputs from −414.30 to −275.34 kJ mol−1 per mole of carbon atoms. The presence of oxygen atoms in organic compounds has a negative impact on the magnitude of combustion heat, with values ranging from 131.1 to 207.17 kJ mol−1. The combustion mechanism imposes certain constraints, leading to the equation HHVg = −31.34·[C] − 144.44·[H] + 10.57·[O] for organic compounds. Based on the parameter sensitivity analysis, the coefficient associated with carbon mass fraction exhibits a significantly greater impact on result prediction accuracy, demonstrating a sensitivity value of 92.65%. The results of further analysis indicate that empirical correlations involving the mass fractions of the elements N and S in lignocellulosic materials may be prone to over-fitting, with sensitivity indices of 1.59% and 0.016%, respectively.
Latest Advancements in the Development of High-Performance Lignin- and Tannin-Based Non-Isocyanate Polyurethane Adhesive for Wood Composites
Authors: Iswanto Apri Heri , Lubis Muhammad Adly Rahandi , Sutiawan Jajang , Al-Edrus Syeed Saifulazry Osman , Lee Seng Hua , Antov Petar , Kristak Lubos , Reh Roman , Mardawati Efri , Santoso Adi , Kusumah Sukma Surya
Published: September 2023

The depletion of natural resources and increasing environmental apprehension regarding the reduction of harmful isocyanates employed in manufacturing polyurethanes (PUs) have generated significant attention from both industrial and academic sectors. This attention is focused on advancing bio-based non-isocyanate polyurethane (NIPU) resins as viable and sustainable substitutes, possessing satisfactory properties. This review presents a comprehensive analysis of the progress made in developing bio-based NIPU polymers for wood adhesive applications. The main aim of this paper is to conduct a comprehensive analysis of the latest advancements in the production of high-performance bio-based NIPU resins derived from lignin and tannin for wood composites. A comprehensive evaluation was conducted on scholarly publications retrieved from the Scopus database, encompassing the period from January 2010 to April 2023. In NIPU adhesive manufacturing, the exploration of substitute materials for isocyanates is imperative, due to their inherent toxicity, high cost, and limited availability. The process of demethylation and carbonation of lignin and tannin has the potential to produce polyphenolic compounds that possess hydroxyl and carbonyl functional groups. Bio-based NIPUs can be synthesized through the reaction involving diamine molecules. Previous studies have provided evidence indicating that NIPUs derived from lignin and tannin exhibit enhanced mechanical properties, decreased curing temperatures and shortened pressing durations, and are devoid of isocyanates. The characterization of NIPU adhesives based on lignin and tannin was conducted using various analytical techniques, including Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), matrix-assisted laser desorption/ionization with time-of-flight (MALDI-TOF) mass spectrometry, and gel permeation chromatography (GPC). The adhesive performance of tannin-based NIPU resins was shown to be superior to that of lignin-based NIPUs. This paper elucidates the potential of lignin and tannin as alternate sources for polyols in the manufacturing of NIPUs, specifically for their application as wood adhesives.
Improving the Anti-washout Property of Acrylate Grouting Material by Bentonite: Its Characterization, Improving Mechanism, and Practical Application
Authors: Li Zuochun , Huang Feng , Yang Yuyou , Xiong Yifan , Su Fei , Wang Yajian , Tian Xiao
Published: September 2023

Acrylate is a popular polymer grouting material that has been widely used to control groundwater seepage. However, the vulnerability of acrylate slurry to dynamic water washout restricts its application in groundwater environments characterized by high flow velocity and water pressures. In this paper, lithium bentonite (Li-B) was used to modify the traditional magnesium acrylate (AC) grouting material. The influence of Li-B to AC ratios on the modified materials’ washout resistance was explored, and the modification mechanism was analyzed using X-ray diffraction (XRD), infrared spectroscopy (IR), and scanning electron microscopy (SEM). Finally, the anti-washout ability of the modified slurry was verified through engineering applications. Results revealed that LiB-AC grout had adjustable setting times (10.5 to 395.6 s), minimal bleeding (0.1%), higher viscosity (65 mPa·s) and expansibility (350%), stronger anti-water dispersibility (24 times that of pure AC slurry), higher mechanical strength (compressive strength is 0.386 MPa, tensile strength is 0.088 MPa), and better impermeability (2.23 × 10−8 m/s). The lithium bentonite was beneficial to the setting time, bleeding, viscosity, slurry retention rate, impermeability, and mechanical strength of the acrylate grout. However, it diminished the expansibility of the acrylate grout. At the optimal acrylate content (20%), the mechanical strength and impermeability of the LiB-AC grout were the highest. The better performance of LiB-AC grout was attributed to the formation of a more stable and dense interlaced spatial network structure after the modification by Li-B. The LiB-AC grout was used in the dynamic water grouting project of a metro shield tunnel segment and achieved better anti-washout performance than cement-water glass and pure AC slurry.
Detailed Study of the Correlation between Cross-Linking of Thick SU-8 and UV–NIR Optical Transmission/Photoluminescence Spectroscopy
Authors: Alharbi Abdullah , Almutairi Dhaifallah , Hussain Hadba , Alfihed Salman
Published: September 2023

SU-8 polymers are promising materials for various applications due to their low cost, excellent thermal stability, and outstanding mechanical properties. Cross-linking of SU-8 is a crucial process that determines the properties of the materials. This study investigates the effect of cross-linking of free-standing SU-8 films on optical transmission and PL emission under various curing conditions. Our findings show that an increase in the cross-linking density reduces optical transmission and causes a red shift of the PL emission band peaks. By directly measuring the optical response of the isolated SU-8, we remove any uncertainty due to the substrate’s presence. Moreover, we show that optical transmission and PL spectroscopy are two non-distractive techniques that can be employed to monitor the curing of the SU-8. This finding enhances our understanding of the cross-linking process in SU-8 and paves the way to further enhance the properties of the SU-8 polymer for various electronics and optoelectronics applications.
The Effect of Chitosan on Physicochemical Properties of Whey Protein Isolate Scaffolds for Tissue Engineering Applications
Authors: Gaweł Martyna , Domalik-Pyzik Patrycja , Douglas Timothy E. L. , Reczyńska-Kolman Katarzyna , Pamuła Elżbieta , Pielichowska Kinga
Published: September 2023

New scaffolds, based on whey protein isolate (WPI) and chitosan (CS), have been proposed and investigated as possible materials for use in osteochondral tissue repair. Two types of WPI-based hydrogels modified by CS were prepared: CS powder was incorporated into WPI in either dissolved or suspended powder form. The optimal chemical composition of the resulting WPI/CS hydrogels was chosen based on the morphology, structural properties, chemical stability, swelling ratio, wettability, mechanical properties, bioactivity, and cytotoxicity evaluation. The hydrogels with CS incorporated in powder form exhibited superior mechanical properties and higher porosity, whereas those with CS incorporated after dissolution showed enhanced wettability, which decreased with increasing CS content. The introduction of CS powder into the WPI matrix promoted apatite formation, as confirmed by energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) analyses. In vitro cytotoxicity results confirmed the cytocompatibility of CS powder modified WPI hydrogels, suggesting their suitability as cell scaffolds. These findings demonstrate the promising potential of WPI/CS scaffolds for osteochondral tissue repair.
Recent Developments in the Detection of Organic Contaminants Using Molecularly Imprinted Polymers Combined with Various Analytical Techniques
Authors: Nazim Tomasz , Lusina Aleksandra , Cegłowski Michał
Published: September 2023

Molecularly imprinted polymers (MIPs) encompass a diverse array of polymeric matrices that exhibit the unique capacity to selectively identify a designated template molecule through specific chemical moieties. Thanks to their pivotal attributes, including exceptional selectivity, extended shelf stability, and other distinct characteristics, this class of compounds has garnered interest in the development of highly responsive sensor systems. As a result, the incorporation of MIPs in crafting distinctive sensors and analytical procedures tailored for specific analytes across various domains has increasingly become a common practice within contemporary analytical chemistry. Furthermore, the range of polymers amenable to MIP formulation significantly influences the potential utilization of both conventional and innovative analytical methodologies. This versatility expands the array of possibilities in which MIP-based sensing can be employed in recognition systems. The following review summarizes the notable progress achieved within the preceding seven-year period in employing MIP-based sensing techniques for analyte determination.
Study on Mechanical Properties and Failure Mechanisms of Highly Filled Hydroxy-Terminated Polybutadiene Propellant under Different Tensile Loading Conditions
Authors: Wu Chengfeng , Lu Yingying , Jiang Ming , Hu Shaoqing , Yang Hongtao , Fu Xiaolong , Li Hongyan
Published: September 2023

To study the mechanical properties of highly filled hydroxy-terminated polybutadiene (HTPB) propellant with 90 wt% solid fillers, the stress–strain curves of the propellant under different temperatures (−50 to 70 °C) and strain rates (0.000476 to 0.119048 s−1) were obtained by uniaxial tensile test. Moreover, to obtain the glass transition temperature and understand the effect of low temperatures on the mechanical properties of the propellant, DMA experiments were carried out. On this basis, the mechanical response laws of the propellant were analyzed, and the master curves of mechanical properties were established. Furthermore, the fracture features of the propellant under typical loading conditions were obtained by SEM, and the corresponding failure mechanisms were analyzed. The results show that the maximum strength decreases with increasing temperature, while the maximum elongation increases with increasing temperature at the same strain rate. The maximum tensile strength increases with increasing strain rate, while the maximum elongation decreases with increasing strain rate at the same temperature. The maximum tensile strength is lowest with a value of 0.35 MPa when the temperature is 343.15 K and the strain rate is 0.000476 s−1, at which time the maximum elongation reaches the highest with a value of 44%. In terms of failure mechanisms, the propellant shows no particle fracture, and the failure modes of the propellant are mainly matrix tearing and dewetting.
Possibilities of Influencing the Crystallization Process of Bisphenol A- and Bisphenol F-Based Epoxy Resins Used for Hydrophobic Coatings on Concrete
Authors: Seidlová Michaela , Hodul Jakub , Žižková Nikol , Borg Ruben Paul
Published: September 2023

Crystallization of bisphenol A (DGEBA)- and bisphenol F (DGEBF)-based epoxy resins is a natural property of these oligomers. However, manufacturers of coatings and other systems based on these epoxy resins are making efforts to slow down the crystallization process as much as possible, thereby extending the shelf life and improving the competitiveness of their products. This paper focuses on the kinetics of the crystallization process of epoxy resins and the effect of the presence of a certain degree of crystallinity on selected parameters of epoxy-based materials. Furthermore, an analysis of the impact of a certain degree of crystallinity of the epoxy base on the resulting coating parameters was carried out. The highest value of crystallinity (17%) was achieved in the sample containing the highest proportion of DGEBF in the crystallization phase “c”, and the enthalpy of melting (Ht) of the crystalline DGEBF sample was 6.3 J/g. Mechanical parameters as well as chemical and thermal resistance of hydrophobic epoxy systems were investigated. The best abrasion resistance (1.5 cm3/50 cm2) was achieved with the blend containing only amorphous DGEBA. The adhesion of the epoxy samples on concrete was greater than 6.5 MPa. The chemical resistance tests performed showed that, in general, the chemical resistance of epoxy systems decreases with increasing crystallinity content. The tighter arrangement of molecules in the crystalline regions of the epoxy matrix results in an increase in density, strength and hardness. This study presents a comprehensive examination of the crystallization of DGEBA and DGEBF, which is, as yet virtually unavailable. It also contributes to knowledge by outlining the possibility of speeding up or slowing down the crystallization process of epoxy resins, including the principle of selecting nucleating agents.
Influence of Light Conditions on the Antibacterial Performance and Mechanism of Waterborne Fluorescent Coatings Based on Waterproof Long Afterglow Phosphors/PDMS Composites
Authors: Hao Sinan , Qi Yuhong , Zhang Zhanping
Published: September 2023

Marine microbial adhesion is the fundamental cause of large-scale biological fouling. Low surface energy coatings can prevent marine installations from biofouling; nevertheless, their static antifouling abilities are limited in the absence of shear forces produced by seawater. Novel waterborne antifouling coatings inspired by fluorescent coral were reported in this paper. Waterproof long afterglow phosphors (WLAP) were introduced into waterborne silicone elastomers by the physical blending method. The composite coatings store energy during the day, and the various colors of light emitted at night affect the regular physiological activities of marine bacteria. Due to the synergistic effect of fouling-release and fluorescence antifouling, the WLAP/polydimethylsiloxane (PDMS) composite coating showed excellent antifouling abilities. The antibacterial performance of coatings was tested under simulated day-night alternation, continuous light, and constant dark conditions, respectively. The results illustrated that the antibacterial performance of composite coatings under simulated day-night alternation conditions was significantly better than that under continuous light or darkness. The weak lights emitted by the coating can effectively inhibit the adhesion of bacteria. C-SB/PDMS showed the best antibacterial effect, with a bacterial adhesion rate (BAR) of only 3.7%. Constant strong light also affects the normal physiological behavior of bacteria, and the weak light of coatings was covered. The antibacterial ability of coatings primarily relied on their surface properties under continuous dark conditions. The fluorescent effect played a vital role in the synergetic antifouling mechanism. This study enhanced the static antifouling abilities of coatings and provided a new direction for environmentally friendly and long-acting marine antifouling coatings.
Rapid Transformation in Wetting Properties of PTFE Membrane Using Plasma Treatment
Authors: Asrafali Shakila Parveen , Periyasamy Thirukumaran , Kim Seong-Cheol
Published: September 2023

In this paper, we describe the surface modification of polytetrafluoroethylene (PTFE) through the plasma treatment process. Several parameters including different active gases, RF power, distance between the plasma source and sample, and plasma duration were optimized to reduce the hydrophobic nature of PTFE. Three different active gases were used (i.e., N2, O2, and (Ar+H2)); N2 was effective to reduce the hydrophobicity of PTFE within a shorter plasma duration of 2 min. Several surface characterizations including ATR-FTIR, water contact angle, FE-SEM, and XPS were utilized to verify the neat and modified PTFE surface after plasma treatment. The plasma treatment using N2 as an active gas improved the wettability of the PTFE membrane, showing a water contact angle of 109.5° when compared with the neat PTFE (141.9°). The SEM images of plasma-treated PTFE showed greater modifications on the surface indicating non-uniform fiber alignment and torn fibers at several places. The obtained results confirm the fact that plasma treatment is an effective way to modify the PTFE surface without altering its bulk property.
Characteristics and Experimental Research on Performance of the Seal Structure of Deepwater Collet Connector
Authors: Yun Feihong , Chai Hongwei , Zhao Yong , Chen Xi , Pang Nan , Jiang Yang , Zhang Mingxuan , Song Haoyu , Zhang Jian
Published: September 2023

The sealing reliability of collet connectors is essential within underwater production systems. This paper is based on the lens gasket sealing mechanism and Hertzian contact theory, establishing mechanical models for the core sealing components in preloaded and working states and analyzing the minimum required axial preload force for sealing. According to the sealing principles of the connector, the force characteristics of each sealing element are analyzed in both preloaded and working states. The interplay of forces between these elements is subsequently determined. Furthermore, the amplification of axial preload force within the sealing structure is confirmed through simulations of contact characteristics. Finally, the accuracy of theoretical and simulated results is confirmed through experimental validation.
Cavitation Observation and Noise Characteristics in Rectangular Throttling Groove Spool
Authors: Zhang Jian , Fu Jifeng , Zhang Xinyang , Zhang Tao , Wang Yuhang
Published: September 2023

A hydraulic cavitation platform was developed in order to examine the occurrence of cavitation in the rectangular throttling groove spool and its correlation with noise characteristics. The test valve is constructed using PMMA material, which possesses excellent transparency. This transparency enables direct visual examination of cavitation occurring at the throttle slot. Additionally, high-speed photography is employed to observe the flow characteristics of the valve port, facilitating the analysis of cavitation morphology changes. Furthermore, a noise meter is utilized to measure and record the noise level and its corresponding spectrum. The flow field and flow phenomena at the rectangular throttling groove spool were studied using high-speed photography, noise spectrum analysis, and other methods. It is discovered that back pressure has the greatest influence on cavitation and flow separation, followed by the influence of intake pressure on cavitation morphology and noise. As the back pressure lowers, the cavitation morphology changes from flaky to cloudy, and the cavitation intensity, distribution area, and noise level increase. Background noise and cavitation noise have distinct frequency differences; cavitation noise in the rectangular throttling groove spool is high-frequency noise, with a frequency of more than 8 kHz, and the higher the frequency, the greater the difference in noise value. The magnitude of the alterations in noise intensity is minimal. The noise values exhibit slight variations of 2.3 dB, 4 dB, and 4.3 dB under varying back pressure circumstances of 3 MPa, 4 MPa, and 5 MPa inlet pressure, respectively. It is recommended to use the frequency of cavitation noise to detect the cavitation state and monitor the cavitation process. In the low-frequency region, the cavitation noise in the rectangular throttle groove valve core is not significantly different. Once the center frequency surpasses 3.15 kHz, a discernible distinction emerges, with the magnitude of the discrepancy in noise value increasing as the frequency rises. In other words, the cavitation cloud does not pulsate at one single frequency, but rather in a range of relatively high frequencies (more than 3.15 kHz).
Impact of Deep Eutectic Solvents on Kinetics and Folding Stability of Formate Dehydrogenase
Authors: Gajardo-Parra Nicolás F. , Rodríguez Gabriel , Arroyo-Avirama Andrés F. , Veliju Astrit , Happe Thomas , Canales Roberto I. , Sadowski Gabriele , Held Christoph
Published: September 2023

Specifically designed co-solvent mixtures are an efficient way to enhance the kinetics of enzyme-catalyzed reactions without compromising enzyme stability; among them, several deep eutectic solvents have emerged as exciting co-solvent mixtures for biocatalytic reactions. DESs nature allows one to tailor the enzyme-co-solvent interactions by using DESs constituents of diverse functional groups. In this work, the influence of co-solvents (betaine, glycerol, and sorbitol) and two DESs (betaine:glycerol and betaine:sorbitol) on the kinetics of candida boidinii Formate dehydrogenase was evaluated. The results showed a 30% increase in catalytic efficiency by adding 15 wt.-% of betaine to the buffered aqueous reaction media. Further, cbFDH folded-state stability was evaluated using differential scanning fluorimetry to finally obtain the binding affinity, unfolding curves, and thermodynamic unfolding parameters. The addition of glycerol, sorbitol, and DESs increased cbFDH protection against thermal stress, and this effect could be improved by increasing co-solvent concentrations. Moreover, DESs showed the ability to reduce the irreversibility of the unfolding process. Betaine was the only co-solvent that had a negative stability effect, which was offset by using betaine-based DESs. The latter was a result of the additivity of certain individual co-solvent effects on thermal stability. Non-monotonous stability effects were obtained by adding sorbitol to the buffer solutions, probably because hydrogen bond dynamics between cbFDH/co-solvent/water change dramatically with the amount of water present. Finally, DESs improved NAD+ binding affinity with cbFDH interestingly without direct correlation with the results obtained for kinetics.
Study on Connectivity Analysis and Injection–Production Optimization of Strong Heterogeneous Sandstone Reservoir Based on Connectivity Method
Authors: Zhou Yuhui , Pu Liang , Dang Sisi , He Jibo , Pu Shuang
Published: September 2023

The D reservoir in the Bongor Basin, southern Chad, is highly heterogeneous. In the stage of waterflood development, the injected water is seriously channeled along the dominant channel, and the water drive effect becomes worse. At the same time, due to the strong edge and bottom water, the water flooding situation is aggravated, the water cut is increased, and the development efficiency is reduced. To accurately identify the inter-well connectivity relationship, we developed a reservoir inter-well connectivity model based on the principle of inter-well connectivity and dynamic production data and reservoir geological parameters. Thus, the plane water injection split coefficient and water injection efficiency of each reservoir layer were obtained. The results are in good agreement with the calculation results of inter-well connectivity through verification with field tracer interpretation. The practical application results show that the method can increase the annual output of oil by 1.3%, which has a good oil increase effect. In this study, a model of inter-well connectivity in multi-layer sandstone reservoirs was established for the first time. The production performance of the model injection–production well was optimized in real time by a historical fitting and production optimization algorithm and then applied to real reservoirs, so that it could effectively improve the oilfield development and optimize the injection–production structure.
Limitation in the Performance of Fine Powder Separation in a Turbo Air Classifier
Authors: Abohelwa Mohamed , Benker Bernd , Javadi Mehran , Wollmann Annett , Weber Alfred P.
Published: September 2023

The deflector wheel classifier is a widely used device for the separation of fine powders in different industrial applications. The primary objective of the separation process is to achieve high-quality separation of fine powders characterized by a narrow particle size distribution and high separation sharpness. Theoretically, the reduction in the cut size is accomplished by decreasing the gas flow rate or increasing the rotational speed of the classifier, which amplifies the centrifugal forces compared to the drag forces exerted on the particles. This behavior is, indeed, observed in many cases, but it cannot be extrapolated arbitrarily. At their performance limit, classifiers may, against expectation, show an increase in cut size and, in addition, a reduction in the sharpness of the separation process. The limitation in the reduction in the cut size and in the improvement in the separation sharpness arises due to an imbalance between the operating rotational speed and flow rate, which results in a non-uniform flow field in the classifier. If the balance conditions are fulfilled, an optimum separation with a high separation sharpness can be achieved. In this work, CFD simulations validated by some experimental results are employed to represent this limitation, which is obtained by varying the operating parameters using different material densities with particles ranging from one to ten microns.
Electrochemical Behavior of Dysprosium Ion and Its Co-Electroreduction with Nickel Ions in the Molten KCl-NaCl-CsCl Eutectic
Authors: Khushkhov Khasbi B. , Kholkina Anna S. , Khotov Astemir A. , Ali Zhubagi Z. , Zhanikayeva Zalina A. , Kvashin Vadim A. , Kovrov Vadim A. , Mushnikova Anastasia A. , Mirzayants Daria P.
Published: September 2023

The electrochemical behavior of dysprosium ions, as well as dysprosium and nickel ion co-reduction, on inert tungsten electrodes and active nickel electrodes were studied in the eutectic KCl-NaCl-CsCl melt at a temperature of 823 K using the methods of cyclic and square-wave voltammetry and open circuit chronopotentiometry. The process of Dy3+ ions electroreduction was found to be reversible and to proceed within a single three-electron stage up to the polarization rate of 0.1 V/s. The increase in the polarization rate indicates a slower rate of the charge transfer, which causes the quasi-reversible character of the charge transfer. It is shown that when the KCl-NaCl-CsCl eutectic melt contains both nickel and dysprosium ions, the voltammetry curves at 823 K have a wave of nickel ion reduction at the potentials of −(0.22–0.28) V and a dysprosium ion reduction at the potentials of −(2.175–2.250) V relative to a chlorine-silver reference electrode. Apart from these waves, the voltammograms have two reduction waves at the potentials of −(1.9–1.95) V and −(2.05–2.1) V. These waves are associated with the reduction of dysprosium ions and their depolarization on metallic nickel, which was preliminary deposited on the tungsten electrode, as well as the formation of the intermetallic phases of dysprosium and nickel of various DyxNiy compositions. The (E-t) dependencies of the open circuit chronopotentiometry elucidate plateaus of the potential delay, which correspond to the dissolution of separate dysprosium and nickel intermetallic phases. Based on the results of the voltammetry changes and the chronopotentiometry of the open circuit, a series of electrochemical syntheses were performed in the potentiostatic regime at the potentials of −(1.7–2.1) V. The intermetallic phases of DyNi5, DyNi3 and DyNi2 were obtained at a definite ratio of the dysprosium and nickel chloride concentrations in the KCl-NaCl-CsCl eutectic melt and at a temperature of 823 K. The synthesized intermetallic samples were characterized by X-ray diffraction and scanning electron microscopy.
Low-Pressure Hydrothermal Processing of Disposable Face Masks into Oils
Authors: Un Cagri , Gentilcore Clayton , Ault Kathryn , Gieng Hung , Vozka Petr , Wang Nien-Hwa Linda
Published: September 2023

A total of 5.4 million tons of face masks were generated worldwide annually in 2021. Most of these used masks went to landfills or entered the environment, posing serious risks to wildlife, humans, and ecosystems. In this study, batch low-pressure hydrothermal processing (LP-HTP) methods are developed to convert disposable face masks into oils. Three different materials from face masks were studied to find optimal processing conditions for converting full face masks into oil. The oil and gas yields, as well as oil compositions, depend on the feedstock composition, particle size, and reaction conditions. Yields of 82 wt.% oil, 17 wt.% gas, and minimal char (~1 wt.%) were obtained from full masks. LP-HTP methods for converting face masks have higher oil yields than pyrolysis methods in the literature and have lower operating pressures than supercritical water liquefaction. LP-HTP methods for face masks can increase net energy returns by 3.4 times and reduce GHG emissions by 95% compared to incineration. LP-HTP has the potential to divert 5.4 million tons of waste masks annually from landfills and the environment, producing approximately 4.4 million tons of oil.