bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymer Cold-Flow Improvers for Biodiesel
Authors: Nifant’ev Ilya , Ivchenko Pavel
Published: May 2021

In recent decades, biodiesel has been explored as a prospective comparable fuel to petroleum diesel for compression ignition engines. However, several drawbacks have limited the wide application of biodiesel as motor fuel, and the poor cold-flow property is one of the major problems. This problem is compounded by the diversity of the biodiesel characteristics arising from a variety of chemical compositions of biodiesel from different sources. Among the methods investigated to improve the cold-flow properties of biodiesel, the use of additives seems highly promising. Despite the significant number of publications, the potential of this method is still far from having been completely discovered or exploited. In the present review, we briefly describe the sources, chemical composition, and physico-chemical characteristics of the main types of biodiesel. Next, we discuss the examples of the use of different polymer additives for the improvement of the cold-flow characteristics of biodiesel and biodiesel/petroleum diesel blends. Additionally, we tried to assess the prospects of the polymer additives to enhance biodiesel performance. The main conclusion of this survey is that innovative and high-efficiency cold-flow improvers for biodiesel should be further developed.
Analysis of Polyhydroxyalkanoates Granules in Haloferax mediterranei by Double-Fluorescence Staining with Nile Red and SYBR Green by Confocal Fluorescence Microscopy
Authors: Cánovas Verónica , Garcia-Chumillas Salvador , Monzó Fuensanta , Simó-Cabrera Lorena , Fernández-Ayuso Carmen , Pire Carmen , Martínez-Espinosa Rosa María
Published: May 2021

Haloferaxmediterranei is a haloarchaeon of high interest in biotechnology because it produces and mobilizes intracellular polyhydroxyalkanoate (PHA) granules during growth under stress conditions (limitation of phosphorous in the culture media), among other interesting metabolites (enzymes, carotenoids, etc.). The capability of PHA production by microbes can be monitored with the use of staining-based methods. However, the staining of haloarchaea cells is a challenging task; firstly, due to the high ionic strength of the medium, which is inappropriate for most of dyes, and secondly, due to the low permeability of the haloarchaea S-layer to macromolecules. In this work, Haloferax mediterranei is used as a halophilic archaeon model to describe an optimized protocol for the visualization and analysis of intracellular PHA granules in living cells. The method is based on double-fluorescence staining using Nile red and SYBR Green by confocal fluorescence microscopy. Thanks to this method, the capability of PHA production by new haloarchaea isolates could be easily monitored.
Intumescent Flame Retardant Mechanism of Lignosulfonate as a Char Forming Agent in Rigid Polyurethane Foam
Authors: Lu Weimiao , Ye Jiewang , Zhu Lianghai , Jin Zhenfu , Matsumoto Yuji
Published: May 2021

Intumescent flame retardants (IFR) have been widely used to improve flame retardancy of rigid polyurethane (RPU) foams and the most commonly used char forming agent is pentaerythritol (PER). Lignosulfonate (LS) is a natural macromolecule with substantial aromatic structures and abundant hydroxyl groups, and carbon content higher than PER. The flame retardancy and its mechanism of LS as char forming agent instead of PER in IFR formulation were investigated by scanning electron microscopy, thermogravimetric analysis, limiting oxygen index testing and cone calorimeter test. The results showed LS as a char forming agent did not increase the density of RPU/LS foams. LOI value and char residue of RPU/LS foam were higher than RPU/PER and the mass loss of RPU/LS foam decreased 18%, suggesting enhanced thermal stability. CCT results showed LS as a char forming agent in IFR formulation effectively enhanced the flame retardancy of RPU foams with respect to PER. The flame retardancy mechanism showed RPU/LS foam presented a continuous and relatively compact char layer, acting as the effect of the flame retardant and heat insulation between gaseous and condensed phases. The efficiency of different LS ratio in IFR formulation as char forming agent was different, and the best flame retardancy and thermal stability was obtained at RPU/LS1.
A Selective Ratiometric Fluorescent Probe for No-Wash Detection of PVC Microplastic
Authors: Caponetti Valeria , Mavridi-Printezi Alexandra , Cingolani Matteo , Rampazzo Enrico , Genovese Damiano , Prodi Luca , Fabbri Daniele , Montalti Marco
Published: May 2021

Microplastics (MP) are micrometric plastic particles present in drinking water, food and the environment that constitute an emerging pollutant and pose a menace to human health. Novel methods for the fast detection of these new contaminants are needed. Fluorescence-based detection exploits the use of specific probes to label the MP particles. This method can be environmentally friendly, low-cost, easily scalable but also very sensitive and specific. Here, we present the synthesis and application of a new probe based on perylene-diimide (PDI), which can be prepared in a few minutes by a one-pot reaction using a conventional microwave oven and can be used for the direct detection of MP in water without any further treatment of the sample. The green fluorescence is strongly quenched in water at neutral pH because of the formation dimers. The ability of the probe to label MP was tested for polyvinyl chloride (PVC), polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), poly methyl methacrylate (PMMA) and polytetrafluoroethylene (PTFE). The probe showed considerable selectivity to PVC MP, which presented an intense red emission after staining. Interestingly, the fluorescence of the MP after labeling could be detected, under excitation with a blue diode, with a conventional CMOS color camera. Good selectivity was achieved analyzing the red to green fluorescence intensity ratio. UV–Vis absorption, steady-state and time-resolved fluorescence spectroscopy, fluorescence anisotropy, fluorescence wide-field and confocal laser scanning microscopy allowed elucidating the mechanism of the staining in detail.
Insight into the Alcohol-Free Ring-Opening Polymerization of TMC Catalyzed by TBD
Authors: Azemar Fabrice , Gimello Olinda , Pinaud Julien , Robin Jean-Jacques , Monge Sophie
Published: May 2021

We report herein a study on the alcohol-free, ring-opening polymerization of trimethylene carbonate (TMC) in THF, catalyzed by 1,5,7-triazabicyclo [4.4.0] ec-5-ene (TBD) with ratios nTBD/nTMC ranging between 1/20 and 1/400. In all cases, the reaction proceeds very rapidly, even faster than in the presence of alcohol initiators, and provides PTMC with molecular weights up to Mn = 34,000 g mol−1. Characterization of the obtained PTMC samples by MALDI-TOF mass spectrometry, triple detection size exclusion chromatography and 1H NMR spectroscopy reveals the presence of both linear and cyclic polymer chains.
PCL/Andiroba Oil (Carapa guianensis Aubl.) Hybrid Film for Wound Healing Applications
Authors: Silva Debora F. , Lima Klinsmann T. , Bastos Gilmara N. T. , Oliveira Johnatt Allan R. , do Nascimento Luís Adriano S. , Costa Carlos Emmerson F. , Filho Geraldo N. R. , Concha Viktor O. C. , Passos Marcele F.
Published: May 2021

Developing a biomimetic material to wound care is an emerging need for the healing process. Poly (ε-caprolactone) (PCL) is a polymer with the necessary dressing’s requirements often used in medicine. Their surface, physic-chemical and biological properties can be modified by adding bioactive compounds, such as andiroba seed oil (Carapa guianensis). This Amazonian natural plant has medicinal and pharmacological properties. For this purpose, PCL polymeric films incorporated with andiroba oil were investigated. The synthesis of hybrids materials was carried out in the solvent casting method. Thermal properties were evaluated using thermogravimetric analysis (TGA/DTGA) and differential scanning calorimetry (DSC). The solvent type on the surface and hydrophilicity of samples was studied using a scanning electron microscope (SEM). Additionally, contact angle measurements, functional groups analysis, fluid absorption capacity, and cell viability were performed. The results demonstrated the influences of andiroba oil under the morphology and thermal properties of the polymeric matrix; the hydrophilicity of the hybrid film obtained by acetic acid was reduced by 13%; the porosity decreased as the concentration of oil increased, but its higher thermal stability. The L929 cell line’s proliferation was observed in all materials, and it presented nontoxic nature. It was demonstrated the ability of PCL hybrid film as a matrix for cell growth. Then, the materials were proved potential candidates for biomedical applications.
Lignin-Containing Coatings for Packaging Materials—Pilot Trials
Authors: Javed Asif , Rättö Peter , Järnström Lars , Ullsten Henrik
Published: May 2021

One severe weakness of most biopolymers, in terms of their use as packaging materials, is their relatively high solubility in water. The addition of kraft lignin to starch coating formulations has been shown to reduce the water solubility of starch in dry coatings. However, lignin may also migrate into aqueous solutions. For this paper, kraft lignin isolated using the LignoBoost process was used in order to examine the effect of pH level on the solubility of lignin with and without ammonium zirconium carbonate (AZC). Machine-glazed (MG) paper was coated in a pilot coating machine, with the moving substrate at high speed, and laboratory-coated samples were used as a reference when measuring defects (number of pinholes). Kraft lignin became soluble in water at lower pH levels when starch was added to the solution, due to the interactions between starch and lignin. This made it possible to lower the pH of the coating solutions, resulting in increased water stability of the dry samples; that is, the migration of lignin to the model liquids decreased when the pH of the coating solutions was reduced. No significant difference was observed in the water vapor transmission rate (WVTR) between high and low pH for the pilot-coated samples. The addition of AZC to the formulation reduced the migration of lignin from the coatings to the model liquids and led to an increase in the water contact angle, but also increased the number of pinholes in the pilot-coated samples.
Analysis of Styrene-Butadiene Based Thermoplastic Magnetorheological Elastomers with Surface-Treated Iron Particles
Authors: Tagliabue Arturo , Eblagon Fernando , Clemens Frank
Published: May 2021

Magnetorheological elastomers (MRE) are increasing in popularity in many applications because of their ability to change stiffness by applying a magnetic field. Instead of liquid-based 1 K and 2 K silicone, thermoplastic elastomers (TPE), based on styrene-butadiene-styrene block copolymers, have been investigated as matrix material. Three different carbonyl iron particles (CIPs) with different surface treatments were used as magneto active filler material. For the sample fabrication, the thermoplastic pressing method was used, and the MR effect under static and dynamic load was investigated. We show that for filler contents above 40 vol.-%, the linear relationship between powder content and the magnetorheological effect is no longer valid. We showed how the SiO2 and phosphate coating of the CIPs affects the saturation magnetization and the shear modulus of MRE composites. A combined silica phosphate coating resulted in a higher shear modulus, and therefore, the MR effect decreased, while coating with SiO2 only improved the MR effect. The highest performance was achieved at low deformations; a static MR effect of 73% and a dynamic MR effect of 126% were recorded. It was also shown that a lower melting viscosity of the TPE matrix helps to increase the static MR effect of anisotropic MREs, while low shear modulus is crucial for achieving high dynamic MR. The knowledge from TPE-based magnetic composites will open up new opportunities for processing such as injection molding, extrusion, and fused deposition modeling (FDM).
Toxic or Not Toxic, That Is the Carbon Quantum Dot’s Question: A Comprehensive Evaluation with Zebrafish Embryo, Eleutheroembryo, and Adult Models
Authors: Chung Chih-Yu , Chen Yu-Ju , Kang Chia-Hui , Lin Hung-Yun , Huang Chih-Ching , Hsu Pang-Hung , Lin Han-Jia
Published: May 2021

Carbon quantum dots (CQDs) are emerging novel nanomaterials with a wide range of applications and high biocompatibility. However, there is a lack of in-depth research on whether CQDs can cause acute or long-term adverse reactions in aquatic organisms. In this study, two different types of CQDs prepared by ammonia citrate and spermidine, namely CQDAC and CQDSpd, were used to evaluate their biocompatibilities. In the fish embryo acute toxicity test (FET), the LD50 of CQDAC and CQDSpd was about 500 and 100 ppm. During the stage of eleutheroembryo, the LD50 decreased to 340 and 55 ppm, respectively. However, both CQDs were quickly eliminated from embryo and eleutheroembryo, indicating a lack of bioaccumulation. Long-term accumulation of CQDs was also performed in this study, and adult zebrafish showed no adverse effects in 12 weeks. In addition, there was no difference in the hatchability and deformity rates of offspring produced by adult zebrafish, regardless of whether they were fed CQDs or not. The results showed that both CQDAC and CQDSpd have low toxicity and bioaccumulation to zebrafish. Moreover, the toxicity assay developed in this study provides a comprehensive platform to assess the impacts of CQDs on aquatic organisms in the future.
Poly(ethylene-imine)-Functionalized Magnetite Nanoparticles Derivatized with Folic Acid: Heating and Targeting Properties
Authors: Ortega-Muñoz Mariano , Plesselova Simona , Delgado Angel V. , Santoyo-Gonzalez Francisco , Salto-Gonzalez Rafael , Giron-Gonzalez Maria Dolores , Iglesias Guillermo R. , López-Jaramillo Francisco Javier
Published: May 2021

Magnetite nanoparticles (MNPs) coated by branched poly (ethylene-imine) (PEI) were synthesized in a one-pot. Three molecular weights of PEI were tested, namely, 1.8 kDa (sample MNP-1), 10 kDa (sample MNP-2), and 25 kDa (sample MNP-3). The MNP-1 particles were further functionalized with folic acid (FA) (sample MNP-4). The four types of particles were found to behave magnetically as superparamagnetic, with MNP-1 showing the highest magnetization saturation. The particles were evaluated as possible hyperthermia agents by subjecting them to magnetic fields of 12 kA/m strength and frequencies ranging between 115 and 175 kHz. MNP-1 released the maximum heating power, reaching 330 W/g at the highest frequency, in the high side of reported values for spherical MNPs. In vitro cell viability assays of MNP-1 and MNP-4 against three cell lines expressing different levels of FA receptors (FR), namely, HEK (low expression), and HeLa (high expression), and HepG2 (high expression), demonstrated that they are not cytotoxic. When the cells were incubated in the presence of a 175 kHz magnetic field, a significant reduction in cell viability and clone formation was obtained for the high expressing FR cells incubated with MNP-4, suggesting that MNP-4 particles are good candidates for magnetic field hyperthermia and active targeting.
Mechanical Properties of Biocomposites Using Polypropylene and Sesame Oil Cake
Authors: Lee Ju-Heon , Kim Dong Hwi , Ryu Youngjae , Kim Kwan Hoon , Jeong Seong Ho , Kim Tae Yang , Cha Sung Woon
Published: May 2021

Sesame oil cakes (SOC) produced during sesame oil production can be classified as plant residues. This study aims to use SOC as a composite material for injection molding. A biocomposite containing polypropylene (PP) and SOC, namely PP/SOC, was developed and its mechanical properties were evaluated. PP/SOC is largely divided into Homo-PP/SOC (HPS) based on Homo-PP and Block-PP/SOC (BPS) based on block-PP. The specimens containing 0–50 wt% SOC were prepared through extrusion and injection molding. As a result of the evaluation, SOC acted as a reinforcement in the matrix, and HPS and BPS showed improved flexural modulus by 36.4% and 37.3% compared to the neat PP, respectively. Tensile strength, on the other hand, decreased by 58% and 55.1%, respectively. To analyze the cause of this, cross-section observation was conducted through scanning electron microscope (SEM), and phase separation and voids were confirmed to be the cause of this. Impact strength of PP/SOC tended to vary depending on the type of matrix. HPS increased by 30.9% compared to neat PP, and BPS decreased by 25%. This tendency difference appears to be the result of SOC inhibiting crystallization of PP, and it has been confirmed through x ray diffraction (XRD) and differential scanning calorimetry (DSC) analysis. Moreover, PP/SOC can be manufactured at a low cost and is environmentally friendly because it utilizes SOC, a plant residue. It can also be applied to commercial products, such as food packaging, owing to its good moldability and improved mechanical properties.
Composite Poly(vinyl alcohol)-Based Nanofibers Embedding Differently-Shaped Gold Nanoparticles: Preparation and Characterization
Authors: Dodero Andrea , Castellano Maila , Lova Paola , Ottonelli Massimo , Brunengo Elisabetta , Vicini Silvia , Alloisio Marina
Published: May 2021

Poly(vinyl alcohol) nanofibrous mats containing ad hoc synthesized gold nanostructures were prepared via a single-step electrospinning procedure and investigated as a novel composite platform with several potential applications. Specifically, the effect of differently shaped and sized gold nanostructures on the resulting mat physical-chemical properties was investigated. In detail, nearly spherical nanoparticles and nanorods were first synthesized through a chemical reduction of gold precursors in water by using (hexadecyl)trimethylammonium bromide as the stabilizing agent. These nanostructures were then dispersed in poly(vinyl alcohol) aqueous solutions to prepare nanofibrous mats, which were then stabilized via a humble thermal treatment able to enhance their thermal stability and water resistance. Remarkably, the nanostructure type was proven to influence the mesh morphology, with the small spherical nanoparticles and the large nanorods leading to thinner well defined or bigger defect-rich nanofibers, respectively. Finally, the good mechanical properties shown by the prepared composite mats suggest their ease of handleability thereby opening new perspective applications.
Chitosan/Montmorillonite Coatings for the Fabrication of Food-Safe Greaseproof Paper
Authors: Wang Kaipeng , Zhao Lihong , He Beihai
Published: May 2021

Here, we report a non-toxic method for improving the oil-resistant performance of chitosan coated paper by coating the mixture of chitosan and montmorillonite (MMT) instead of coating chitosan solution only. Through combining MMT into the chitosan coatings, the coated paper exhibited a lower air permeability and enhanced oil resistance under a lower coating load. For coated papers C2.5 and C3 by coating 2.5% (w/v) and 3% (w/v) chitosan without adding MMT in the chitosan coating, the coating load was 3.76 g/m2 and 3.99 g/m2, respectively, and the kit rating values were only 7–8/12. Regarding the sample C2M0.1 coated by the mixed solution containing 2% (w/v) chitosan and 0.1% (w/v) MMT, its coating load was only 3.65 g/m2, the paper permeability after coating was reduced to 0.00507 μm/Pa·s, owing to the filling of MMT into the cellulosic fibers network, and the kit rating reached 9/12. Moreover, C2M0.1 showed improved mechanical properties, whereby its tearing resistance was 5.2% and 6.6% higher than that of the uncoated paper in the machine direction and the cross direction, respectively.
Self-Healing Performance of Smart Polymeric Coatings Modified with Tung Oil and Linalyl Acetate
Authors: Ismail Norhan Ashraf , Khan Adnan , Fayyad Eman , Kahraman Ramazan , Abdullah Aboubakr M. , Shakoor Rana Abdul
Published: May 2021

This work focuses on the synthesis and characterization of polymeric smart self-healing coatings. A comparison of structural, thermal, and self-healing properties of two different polymeric coatings comprising distinct self-healing agents (tung oil and linalyl acetate) is studied to elucidate the role of self-healing agents in corrosion protection. Towards this direction, urea-formaldehyde microcapsules (UFMCs) loaded with tung oil (TMMCs) and linalyl acetate (LMMCs) were synthesized using the in-situ polymerization method. The synthesis of both LMMCs and TMMCs under identical experimental conditions (900 rpm, 55 °C) has resulted in a similar average particle size range (63–125 µm). The polymeric smart self-healing coatings were developed by reinforcing a polymeric matrix separately with a fixed amount of LMMCs (3 wt.% and 5 wt.%), and TMMCs (3 wt.% and 5 wt.%) referred to as LMCOATs and TMCOATs, respectively. The development of smart coatings (LMCOATs and TMCOATs) contributes to achieving decent thermal stability up to 450 °C. Electrochemical impedance spectroscopy (EIS) analysis indicates that the corrosion resistance of smart coatings increases with increasing concentration of the microcapsules (TMMCs, LMMCs) in the epoxy matrix reaching ~1 GΩ. As a comparison, LMCOATs containing 5 wt.% LMMCs demonstrate the best stability in the barrier properties than other developed coatings and can be considered for many potential applications.
PLA-Based Materials Containing Bio-Plasticizers and Chitosan Modified with Rosehip Seed Oil for Ecological Packaging
Authors: Darie-Niță Raluca , Râpă Maria , Sivertsvik Morten , Rosnes Jan , Popa Elisabeta , Dumitriu Raluca , Marincaș Octaviana , Matei Ecaterina , Predescu Cristian , Vasile Cornelia
Published: May 2021

Several recipes based on PLA, bio-plasticizers, and active agents such as vitamin E and cold-pressed rosehip seed oil encapsulated into chitosan by the emulsion method named here as chitosan modified (CS-M) were elaborated by melt compounding for food packaging applications. Resulted biocomposites have been investigated from the point of view of physical-mechanical, thermal, barrier, antimicrobial, and antioxidant properties to select the formulations with the optimum features to produce food trays and films for packaging applications. The obtained results showed that the elaborated formulations exhibit tensile strength and flexibility dependent on their composition being either rigid or flexible, as well as antimicrobial and antioxidant activity, which will potentially lead to prolonged use for food packaging. The recipe with PLA matrix and 40:60 Lapol®108 as masterbarch/polyethylene glycol (MB/PEG) bio-plasticizers ratio was distinguished by an improvement of over 100 times in terms of flexibility compared with neat PLA, while the highest antioxidant activity (36.27%) was recorded for the sample containing a CS-M and MB/PEG ratio of 60:40. An enhancement of ~50% for the water vapor barrier was recorded for PLA/CS-M_100:0 material. By modulating the MB and PEG bio-plasticizers ratio, the design of new eco-friendly food packaging materials with antimicrobial/antioxidant characteristics by using the existing technologies for processing synthetic polymers (melt mixing, compounding, pressing, thermoforming) has been successfully realized.
Microstructure and Mechanical Properties of Polyacrylonitrile Precursor Fiber with Dry and Wet Drawing Process
Authors: Ahn Hyunchul , Wee Jae-Hyung , Kim Yong Min , Yu Woong-Ryeol , Yeo Sang-Young
Published: May 2021

Polyacrylonitrile (PAN) fibers are typically used as precursor fibers for carbon fiber production, produced through wet-spinning processes. The drawing process of the spun fiber can be classified into dry and wet drawing processes. It is known that the drawing stability and stretching ratio differ depending on the drawing process; however, the elementary characteristics are approximately similar. In this study, the mechanical properties of PAN fibers have been examined based on these two drawing processes with the differences analyzed through the analysis of microstructures. Further, to examine the composition of the fiber, element analysis has been conducted, and thereafter, the microstructure of the fiber is examined through X-ray diffraction analysis. Finally, the characteristics of PAN fibers and its mechanical properties has been examined according to each drawing condition. There are differences in moisture content and microstructure according to the drawing process, and it affects the tensile behavior. The results obtained could have potential implications if the processes are combined, as it could result in a design for a stable and highly efficient drawing process.
Synthesis of a New Polyanion Possessing Dense 1,2,3-Triazole Backbone
Authors: Xu Linlin , Kamon Yuri , Hashidzume Akihito
Published: May 2021

Polyanions are an important class of water-soluble polymers because polyanions are utilized in a wide range of industrial fields. It is thus a great challenge to develop polyanions with novel structures to make their applications broader. In this study, a new polyanion with a dense 1,2,3-triazole backbone, poly(4-azido-5-hexanoic acid) (poly(AH)), was synthesized by copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) polymerization of t-butyl 4-azido-5-hexanoate followed by hydrolysis of the t-butyl ester groups. Turbidimetric and potentiometric titration data indicated that poly(AH) was well soluble in water under basic conditions (pH < 7) and a weaker polyanion (apparent pKa = 5.4) than polyacrylic acid (apparent pKa = 4.5). Adsorption tests exhibited that sodium salt of poly(AH) (poly(AH)Na) adsorbed most preferably Fe3+ among the four metal ions examined, i.e., Cu2+, Pb2+, Li+, and Fe3+. 1H spin-lattice relaxation time measurements indicated that Fe3+ ions were adsorbed favorably onto the 1,2,3-triazole residues.
A Facile Synthesis Route of Hybrid Polyurea-Polyurethane-MWCNTs Nanocomposite Coatings for Ballistic Protection and Experimental Testing in Dynamic Regime
Authors: Toader Gabriela , Diacon Aurel , Rusen Edina , Rizea Florica , Teodorescu Mircea , Stanescu Paul O. , Damian Celina , Rotariu Adrian , Trana Eugen , Bucur Florina , Ginghina Raluca
Published: May 2021

This study describes a simple, practical, inexpensive, improved, and efficient novel method for obtaining polyurea-polyurethane-multiwall carbon nanotubes (MWCNTs) nanocomposites with enhanced mechanical properties, and their experimental testing in a dynamic regime. SEM and micro-CT investigations validated the homogeneity of the nanocomposite films and uniform dispersion of the nanofiller inside the polymeric matrix. The experimental measurements (TGA, DSC, DMA, and tensile tests) revealed improved thermal and mechanical properties of these new materials. To demonstrate that these nanocomposites are suitable for ballistic protection, impact tests were performed on aluminum plates coated with the polyurea-polyurethane MWCNTs nanocomposites, using a Hopkinson bar set-up. The experimental testing in the dynamic regime of the polyurea- polyurethane-coated aluminum plates confirmed that the nanocomposite layers allow the metal plate to maintain its integrity at a maximum force value that is almost 200% higher than for the uncoated metallic specimens.
Investigation on the Thermoforming of Pmsq-Hdpe for the Manufacture of a NACA Profile of Small Dimensions
Authors: Fouad Erchiqui , Baatti Abdessamad , Ben Hamou Karima , Kaddami Hamid , Souli Mhamed , Imad Abdellatif
Published: May 2021

Unmanned aerial vehicles (UAVs) or drones are attracting increasing interest in the aviation industry, both for military and civilian applications. The materials used so far in the manufacture of UAVs are wood, plastic, aluminum and carbon fiber. In this regard, a new family of high-density polyethylene (HDPE) nanocomposites reinforced with polymethylsilsesquioxane nanoparticles (PMSQ), with mechanical performances significantly superior to those of pure HPDE, has been prepared by a fusion-combination process. Their viscoelastic properties were determined by oscillatory shear tests and their viscoelastic behavior characterized by the Lodge integral model. Then, the Lagrangian formulation and the membrane theory assumption were used in the explicit implementation of the dynamic finite element formulation. For the forming phase, we considered the thermodynamic approach to express the external work in terms of closed volume. In terms of von Mises stress distribution and thickness in the blade, the results indicate that HDPE-PMSQ behaves like virgin HDPE. Furthermore, its materials, for all intents and purposes, require the same amount of energy to form as HDPE.
Gr/3D–ZnO Nanocomposites as Humidity Sensors with Enhanced Sensing Response
Authors: Lin Wang-De , Lin You-Chen , Wu Ren-Jang , Chavali Murthy
Published: May 2021

This work introduces a novel humidity sensor based on a nanocomposite material comprising graphene decorated with three-dimensional flower-like structures of zinc oxide (Gr/3D–ZnO) fabricated via a hydrothermal method with various weight percentages of graphene. The surface structure and morphology of the Gr/3D–ZnO nanocomposite were analyzed using XRD, EDS, SEM, TEM, and Raman spectroscopy. The influence of humidity on the electrical properties of the nanocomposite was also investigated. Experiment results revealed that the nanocomposite with 70 wt% of graphene provided high sensitivity (S = 446) with rapid response times (120 s) and recovery times (160 s). These results demonstrate the excellent potential of the proposed Gr/3D–ZnO nanocomposite in monitoring atmospheric humidity. A discussion on the mechanism underlying the effects of humidity on the Gr/3D–ZnO nanocomposite is also provided.
Biobased Waterborne Polyurethane-Urea/SWCNT Nanocomposites for Hydrophobic and Electrically Conductive Textile Coatings
Authors: Lacruz Amado , Salvador Mireia , Blanco Miren , Vidal Karmele , Goitandia Amaia M. , Martinková Lenka , Kyselka Martin , de Ilarduya Antxon Martínez
Published: May 2021

Waterborne polyurethane-urea dispersions (WPUD), which are based on 100% bio-based semi-crystalline polyester polyol and isophorone diisocyanate, have been successfully synthesized and doped with single-walled carbon nanotubes (SWCNT) to obtain a finishing agent that provides textiles with multifunctional properties. The chemical structure of WPUD has been characterized by Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The thermal properties have been evaluated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic mechanical thermal analysis (DMTA). Mechanical properties have been studied by tensile stress–strain analysis. Moreover, the particle size, particle size distribution (PSD), and stability of developed waterborne dispersions have been assessed by dynamic light scattering (DLS), Z-potential, and accelerated aging tests (analytical centrifugation). Subsequently, selected fabrics have been face-coated by the WPUD using knife coating method and their properties have been assessed by measuring water contact angle (WCA), water column, fabric stiffness, and air permeability. The electrical conductivity of textiles coated with SWCNT-doped WPUD has been evaluated by EN 1149 standard. Finally, the surface morphologies of uncoated and coated fabrics have been studied by scanning electron microscopy (SEM). All of the synthesized polyurethane-ureas provide the coated substrates with remarkable water-repellency and water column, being therefore a more sustainable alternative to waterproof coatings based on fluoropolymers, such as PTFE. The additivation of the polymeric matrices with SWCNT has led to textile coatings with excellent electrical conductivity, maintaining water column properties, giving rise to multifunctional coatings that are highly demanded in protective workwear and technical textiles.
Nanosponge-Based Composite Gel Polymer Electrolyte for Safer Li-O2 Batteries
Authors: Amici Julia , Torchio Claudia , Versaci Daniele , Dessantis Davide , Marchisio Andrea , Caldera Fabrizio , Bella Federico , Francia Carlotta , Bodoardo Silvia
Published: May 2021

Li-O2 batteries represent a promising rechargeable battery candidate to answer the energy challenges our world is facing, thanks to their ultrahigh theoretical energy density. However, the poor cycling stability of the Li-O2 system and, overall, important safety issues due to the formation of Li dendrites, combined with the use of organic liquid electrolytes and O2 cross-over, inhibit their practical applications. As a solution to these various issues, we propose a composite gel polymer electrolyte consisting of a highly cross-linked polymer matrix, containing a dextrin-based nanosponge and activated with a liquid electrolyte. The polymer matrix, easily obtained by thermally activated one pot free radical polymerization in bulk, allows to limit dendrite nucleation and growth thanks to its cross-linked structure. At the same time, the nanosponge limits the O2 cross-over and avoids the formation of crystalline domains in the polymer matrix, which, combined with the liquid electrolyte, allows a good ionic conductivity at room temperature. Such a composite gel polymer electrolyte, tested in a cell containing Li metal as anode and a simple commercial gas diffusion layer, without any catalyst, as cathode demonstrates a full capacity of 5.05 mAh cm−2 as well as improved reversibility upon cycling, compared to a cell containing liquid electrolyte.
Reinforcement of Styrene Butadiene Rubber Employing Poly(isobornyl methacrylate) (PIBOMA) as High Tg Thermoplastic Polymer
Authors: Gunaydin Abdullah , Mugemana Clément , Grysan Patrick , Eloy Federico Carlos , Dieden Reiner , Schmidt Daniel F. , Westermann Stephan , Weydert Marc , Shaplov Alexander S.
Published: May 2021

A set of poly(isobornyl methacrylate)s (PIBOMA) having molar mass in the range of 26,000–283,000 g mol−1 was prepared either via RAFT process or using free radical polymerization. These linear polymers demonstrated high glass transition temperatures (Tg up to 201 °C) and thermal stability (Tonset up to 230 °C). They were further applied as reinforcing agents in the preparation of the vulcanized rubber compositions based on poly(styrene butadiene rubber) (SBR). The influence of the PIBOMA content and molar mass on the cure characteristics, rheological and mechanical properties of rubber compounds were studied in detail. Moving die rheometry revealed that all rubber compounds filled with PIBOMA demonstrated higher torque increase values ΔS in comparison with rubber compositions without filler, independent of PIBOMA content or molar mass, thus confirming its reinforcing effect. Reinforcement via PIBOMA addition was also observed for vulcanized rubbers in the viscoelastic region and the rubbery plateau, i.e. from −20 to 180 °C, by dynamic mechanical thermal analysis. Notably, while at temperatures above ~125 °C, ultra-high-molecular-weight polyethylene (UHMWPE) rapidly loses its ability to provide reinforcement due to softening/melting, all PIBOMA resins maintained their ability to reinforce rubber matrix up to 180 °C. For rubber compositions containing 20 phr of PIBOMA, both tensile strength and elongation at break decreased with increasing PIBOMA molecular weight. In summary, PIBOMA, with its outstanding high Tg among known poly(methacrylates), may be used in the preparation of advanced high-stiffness rubber compositions, where it provides reinforcement above 120 °C and gives properties appropriate for a range of applications.
Characterization of Bacillus Species from Market Foods in Beijing, China
Authors: Hu Qiao , Fang Yuwen , Zhu Jiajia , Xu Wenjiao , Zhu Kui
Published: May 2021

Foodborne diseases have been witnessing a constant rising trend worldwide, mainly caused by pathogenic microorganisms, such as Bacillus spp., posing a direct threat to public health. The purpose of this study was to evaluate the biological risk of foodborne and probiotic Bacillus spp. in Beijing markets. A total of 55 Bacillus isolates, including 29 B. cereus, 9 B. licheniformis and 7 B. subtilis, mostly found in dairy products (32.7%), were recovered from 106 samples and identified by matrix-assisted laser desorption/ionization mass spectrometry and polymerase chain reaction methods. The susceptibility towards 16 antibiotics was determined using a broth microdilution method. Bacillus showed a high level of resistance to florfenicol (100%), lincomycin (100%), tiamulin (78.2%) and ampicillin (67.3%), while they were all susceptible or intermediate to vancomycin and rifampin. Additionally, we obtained the whole genome of 19 Bacillus strains using high-throughput sequencing, and the rates of resistance genes van, fosB, erm and tet were 57.9%, 57.9%, 21.1% and 26.3%, respectively. Moreover, 100%, 9.1%, 45.5% and 100% of these isolates carried virulence genes nhe, hbl, cytK and entFM, respectively. Lastly, 60% Bacillus strains were positive in hemolysis tests, and 3 B. licheniformis strains displayed an inhibitory activity on the growth of S. aureus ATCC 29213 using agar overlay technique. Our study outlines the characteristics of foodborne Bacillus spp. and provides information for the monitoring of food safety.
Combustion Characteristics and Kinetic Analysis of Biomass Pellet Fuel Using Thermogravimetric Analysis
Authors: Jia Guohai
Published: May 2021

Biomass pellet fuel is one of the development directions of renewable energy. The purpose of the article is to study the combustion characteristics of five kinds of biomass pellet fuel that can be used as biomass fuel and analyze their combustion kinetics. The thermogravimetric method (TG method) was used to analyze the combustion characteristics of five kinds of biomass pellet fuel and to calculate the index S of comprehensive combustion characteristic. The Arrhenius equation and the Coats–Redfern method were used to analyze the combustion kinetics of five kinds of biomass pellet fuel. The activation energy and pre-exponential factor were obtained according to different temperature ranges. Conclusions are as follows: The pyrolysis of five kinds of biomass pellet fuel mainly includes three stages: (1) water evaporation stage, (2) volatile component combustion stage, (3) fixed carbon oxidation stage. The TG curves of five kinds of biomass pellet fuel are roughly the same at the same heating rate. The peaks of thermal weight loss rate and maximum degradation rate are both in the high temperature range. The differential thermal gravity (DTG) curves of five kinds of biomass pellet fuel have an obvious peak. The peak temperature of the largest peak in the DTG curves is 280–310 °C. The first-order reaction equation is used to obtain the kinetic parameters in stages. The correlation coefficients are bigger than the value of 0.92. The fitting results are in good agreement with the experimental results. The activation energy of each sample is basically the same in each stage. The value in the volatile matter combustion stage is 56–542 kJ/mol, and the activation energy of the carbon layer slowly increases rapidly. The five kinds of biomass pellet fuels have good combustion characteristics and kinetic characteristics, and they can be promoted and applied as biomass pellet fuels in the future.
A TITO Control Strategy to Increase Productivity in Uncertain Exothermic Continuous Chemical Reactors
Authors: Aguilar-López Ricardo , Mata-Machuca Juan Luis , Godinez-Cantillo Valeria
Published: May 2021

In this manuscript, a two-input two-output (TITO) control strategy for an exothermic continuous chemical reactor is presented. The control tasks of the continuous chemical reactor are related to temperature regulation by a standard proportional-integral (PI) controller. The selected set point increases reactor productivity due to the temperature effect and prevents potential thermal runaway, and the temperature increases until it reaches isothermal operating conditions. Then, an optimal controller is activated to increase the mass reactor productivity. The optimal control strategy is based on a Euler-Lagrange framework, in which the corresponding Lagrangian is based on the model equations of the reactor, and the optimal controller is coupled with an uncertainty estimator to infer the unknown terms required by the proposed controller. As a benchmark, a continuous stirred tank reactor (CSTR) with a Van de Vusse chemical reaction is considered as an application case study. Notably, the proposed methodology is generally applicable to any continuous stirred tank reactor. The results of numerical experiments verify the satisfactory performance of the proposed control strategy.
Protein L—More Than Just an Affinity Ligand
Authors: Kittler Stefan , Besleaga Mihail , Ebner Julian , Spadiut Oliver
Published: May 2021

In the past 30 years, highly specific drugs, known as antibodies, have conquered the biopharmaceutical market. In addition to monoclonal antibodies (mAbs), antibody fragments are successfully applied. However, recombinant production faces challenges. Process analytical tools for monitoring and controlling production processes are scarce and time-intensive. In the downstream process (DSP), affinity ligands are established as the primary and most important step, while the application of other methods is challenging. The use of these affinity ligands as monitoring tools would enable a platform technology to monitor process steps in the USP and DSP. In this review, we highlight the current applications of affinity ligands (proteins A, G, and L) and discuss further applications as process analytical tools.
Current State of SLC and ABC Transporters in the Skin and Their Relation to Sweat Metabolites and Skin Diseases
Authors: Nielsen Marcus , Aryal Eva , Safari Elnaz , Mojsoska Biljana , Jenssen Håvard , Prabhala Bala
Published: May 2021

With a relatively large surface area (2 m2) and 15% of total body mass, the skin forms the largest organ of the human body. The main functions of the skin include regulation of body temperature by insulation or sweating, regulation of the nervous system, regulation of water content, and protection against external injury. To perform these critical functions, the skin encodes genes for transporters responsible for the cellular trafficking of essential nutrients and metabolites to maintain cellular hemostasis. However, the knowledge on the expression, regulation, and function of these transporters is very limited and needs more work to elucidate how these transporters play a role both in disease progression and in healing. Furthermore, SLC and ABC transporters are understudied, and even less studied in skin. There are sparse reports on relation between transporters in skin and sweat metabolites. This mini review focuses on the current state of SLC and ABC transporters in the skin and their relation to sweat metabolites and skin diseases.
Modelling the Visibility of Baltic-Type Crude Oil Emulsion Dispersed in the Southern Baltic Sea
Authors: Baszanowska Emilia , Otremba Zbigniew , Piskozub Jacek
Published: May 2021

This paper analyses the radiance reflectance modelling of a sea area and the case of a water column polluted with an oil emulsion in relation to various depths of the occurrence of an oil-in-water emulsion in all azimuth and zenith angles. For the radiance reflectance modelling, the simulation of large numbers of solar photons in water was performed using a Monte Carlo simulation. For the simulations, the optical properties of seawater for the open sea typical of the southern Baltic Sea were used and Petrobaltic-type crude oil (extracted in the Baltic Sea) was added. Oil pollution in the sea was considered for oil droplet concentrations of 10 ppm, which were optically represented by spectral waveforms of absorption and scattering coefficients, as well as by angular light scattering distribution determined using the Mie theory. The results of the radiance reflectance modelling in the whole spectrum of both angles, azimuth and zenith, allowed us to select 555 nm as the optimal wavelength for oil emulsion detection. Moreover, the parameter contrast was defined and determined using radiance reflectance results for eight light wavelengths in the range of 412-676 nm. The contrast is discussed in relation to the various thicknesses of polluted water layers. Changes in contrast for a thickness layer 5 m under the sea surface were noted, whereas for thicker layers the contrast remained unchanged.
Multi-Sector Oriented Object Detector for Accurate Localization in Optical Remote Sensing Images
Authors: He Xu , Ma Shiping , He Linyuan , Ru Le , Wang Chen
Published: May 2021

Oriented object detection in optical remote sensing images (ORSIs) is a challenging task since the targets in ORSIs are displayed in an arbitrarily oriented manner and on small scales, and are densely packed. Current state-of-the-art oriented object detection models used in ORSIs primarily evolved from anchor-based and direct regression-based detection paradigms. Nevertheless, they still encounter a design difficulty from handcrafted anchor definitions and learning complexities in direct localization regression. To tackle these issues, in this paper, we proposed a novel multi-sector oriented object detection framework called MSO2-Det, which quantizes the scales and orientation prediction of targets in ORSIs via an anchor-free classification-to-regression approach. Specifically, we first represented the arbitrarily oriented bounding box as four scale offsets and angles in four quadrant sectors of the corresponding Cartesian coordinate system. Then, we divided the scales and angle space into multiple discrete sectors and obtained more accurate localization information by a coarse-granularity classification to fine-grained regression strategy. In addition, to decrease the angular-sector classification loss and accelerate the network’s convergence, we designed a smooth angular-sector label (SASL) that smoothly distributes label values with a definite tolerance radius. Finally, we proposed a localization-aided detection score (LADS) to better represent the confidence of a detected box by combining the category-classification score and the sector-selection score. The proposed MSO2-Det achieves state-of-the-art results on three widely used benchmarks, including the DOTA, HRSC2016, and UCAS-AOD data sets.
Object Tracking in Hyperspectral-Oriented Video with Fast Spatial-Spectral Features
Authors: Chen Lulu , Zhao Yongqiang , Yao Jiaxin , Chen Jiaxin , Li Ning , Chan Jonathan Cheung-Wai , Kong Seong G.
Published: May 2021

This paper presents a correlation filter object tracker based on fast spatial-spectral features (FSSF) to realize robust, real-time object tracking in hyperspectral surveillance video. Traditional object tracking in surveillance video based only on appearance information often fails in the presence of background clutter, low resolution, and appearance changes. Hyperspectral imaging uses unique spectral properties as well as spatial information to improve tracking accuracy in such challenging environments. However, the high-dimensionality of hyperspectral images causes high computational costs and difficulties for discriminative feature extraction. In FSSF, the real-time spatial-spectral convolution (RSSC) kernel is updated in real time in the Fourier transform domain without offline training to quickly extract discriminative spatial-spectral features. The spatial-spectral features are integrated into correlation filters to complete the hyperspectral tracking. To validate the proposed scheme, we collected a hyperspectral surveillance video (HSSV) dataset consisting of 70 sequences in 25 bands. Extensive experiments confirm the advantages and the efficiency of the proposed FSSF for object tracking in hyperspectral video tracking in challenging conditions of background clutter, low resolution, and appearance changes.