bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Chitosan and Its Derivative Polymers in Clinical Medicine and Agriculture
Authors: Zhang Meng , Zhang Fengshi , Li Ci , An Heng , Wan Teng , Zhang Peixun
Published: March 2022

Chitosan is a biodegradable natural polymer derived from the exoskeleton of crustaceans. Because of its biocompatibility and non-biotoxicity, chitosan is widely used in the fields of medicine and agriculture. With the latest technology and technological progress, different active functional groups can be connected by modification, surface modification, or other configurations with various physical, chemical, and biological properties. These changes can significantly expand the application range and efficacy of chitosan polymers. This paper reviews the different uses of chitosan, such as catheter bridging to repair nerve broken ends, making wound auxiliaries, as tissue engineering repair materials for bone or cartilage, or as carriers for a variety of drugs to expand the volume or slow-release and even show potential in the fight against COVID-19. In addition, it is also discussed that chitosan in agriculture can improve the growth of crops and can be used as an antioxidant coating because its natural antibacterial properties are used alone or in conjunction with a variety of endophytic bacteria and metal ions. Generally speaking, chitosan is a kind of polymer material with excellent development prospects in medicine and agriculture.
Polyethyleneimine-Functionalized Carbon Nanotubes Enabling Potent Antimycotic Activity of Lyticase
Authors: Liang Weibing , Chen Ming , Li Lin , Yan Liqiang , Wang Xiuli , Wu Xiongzhi , Lei Chenghong
Published: March 2022

In this work, the positively-charged polymer polyethyleneimine was used to functionalize carbon nanotubes and activated carbon to load antimycotic enzyme lyticase. Interestingly, polyethyleneimine played a dual role functionalizing carbon materials to synergistically enhance antimycotic activity of loaded lyticase as well as exhibiting its own apparent antimycotic activity, where the enhanced enzymatic activity of loaded lyticase on functionalized carbon nanotubes was more than 2.8 times as high as the activity of free enzyme in solution. The actual activity of loaded lyticase on functionalized carbon nanotubes was applied with Penicillium janthinellum, exhibiting much faster digesting lysis of the bacteria in comparison with free lyticase. The synergistic and potent antimycotic activities from combined action of antimycotic lyticase and polyethyleneimine on carbon nanotubes provides a new antimycotic protection for medicine, food industry, and other biochemical processes.
Polyvinylidene Fluoride Surface Polarization Enhancement for Liquid-Solid Triboelectric Nanogenerator and Its Application
Authors: Vu Duy Linh , Le Chau Duy , Ahn Kyoung Kwan
Published: March 2022

Liquid-solid triboelectric nanogenerator (TENG) has been great attention as a promising electricity generation method for renewable energy sources and self-powered electronic devices. Thus, enhancing TENG performance is a critical issue to be concerned for both practical and industrial applications. Hence in this study, a high-output liquid-solid TENG is proposed using a polyvinylidene fluoride surface polarization enhancement (PSPE) for self-powered streamflow sensing, which shows many advantages, such as adapt to the sensor energy requirement, multiple parameters sensing at the same time, eliminate the influence of ion concentration. The TENG based on PSPE film has the maximum power density of 15.6 mW/m2, which is increased by about 4.7 times compared to commercial PVDF-based TENG. This could be attributed to the increase of the dielectric constant and hydrophobic property of the PVDF film after the surface polarization enhancement process. Furthermore, the PSPE-TENG-driven sensor can simultaneously monitor both the physical and chemical parameters of the streamflow with high sensitivity and minimum error detection, which proves that the PSPE-TENG has enormous potential applications in self-powered streamflow sensing.
Features of the Chemical Composition and Structure of Birch Phloem Dioxane Lignin: A Comprehensive Study
Authors: Faleva Anna V. , Pikovskoi Ilya I. , Pokryshkin Sergey A. , Chukhchin Dmitry G. , Kosyakov Dmitry S.
Published: March 2022

Understanding the chemical structure of lignin in the plant phloem contributes to the systematics of lignins of various biological origins, as well as the development of plant biomass valorization. In this study, the structure of the lignin from birch phloem has been characterized using the combination of three analytical techniques, including 2D NMR, Py-GC/MS, and APPI-Orbitrap-HRMS. Due to the specifics of the phloem chemical composition, two lignin preparations were analyzed: a sample obtained as dioxane lignin (DL) by the Pepper’s method and DL obtained after preliminary alkaline hydrolysis of the phloem. The obtained results demonstrated that birch phloem lignin possesses a guaiacyl–syringyl (G-S) nature with a unit ratio of (S/G) 0.7–0.9 and a higher degree of condensation compared to xylem lignin. It was indicated that its macromolecules are constructed from β-aryl ethers followed by phenylcoumaran and resinol structures as well as terminal groups in the form of cinnamic aldehyde and dihydroconiferyl alcohol. The presence of fatty acids and flavonoids removed during alkaline treatment was established. Tandem mass spectrometry made it possible to demonstrate that the polyphenolic components are impurities and are not incorporated into the structure of lignin macromolecules. An important component of phloem lignin is lignin–carbohydrate complexes incorporating xylopyranose moieties.
Improved Melt Processabilities of Thermosetting Polyimide Matrix Resins for High Temperature Carbon Fiber Composite Applications
Authors: Zhang Hao-Yang , Yuan Li-Li , Hong Wei-Jie , Yang Shi-Yong
Published: March 2022

With the goal of improving processability of imide oligomers and achieving of high temperature carbon fiber composite, a series of Thermosetting Matrix Resin solutions (TMR) were prepared by polycondensation of aromatic diamine (3,4′-oxybisbenzenamine, 3,4-ODA) and diester of biphenylene diacid (BPDE) using monoester of 4-phenylethynylphthalic acid (PEPE) as end-capping agent in ethyl alcohol as solvent to afford phenylethynyl-endcapped poly(amic ester) resins with calculated molecular weight (Calc’d Mw) of 1500–10,000. Meanwhile, a series of reactive diluent solutions (RDm) with Calc’d Mw of 600–2100 were also prepared derived from aromatic diamine (4,4′-oxybisbenzenamine, 4,4-ODA), diester of asymmetrical biphenylene diacid (α-BPDE) and monoester of 4-phenylethynylphthalic acid (PEPE) in ethyl alcohol. Then, the TMR solution was mixed with the RDm solution at different weight ratios to afford a series of A-staged thermosetting blend resin (TMR/RDm) solutions for carbon fiber composites. Experimental results demonstrated that the thermosetting blend resins exhibited improved melt processability and excellent thermal stability. After being thermally treated at 200 °C/1 h, the B-staged TMR/RDm showed very low melt viscosities and wider processing window. The minimum melt viscosities of ≤50 Pa·s was measured at ≤368 °C and the temperature scale at melt viscosities of ≤100 Pa·s were detected at 310–390 °C, respectively. The thermally cured neat resins at 380 °C/2 h showed a great combination of mechanical and thermal properties, including tensile strength of 84.0 MPa, elongation at breakage of 4.1%, and glass transition temperature (Tg) of 423 °C, successively. The carbon fiber reinforced polyimide composite processed by autoclave technique exhibited excellent mechanical properties both at room temperature and 370 °C. This study paved the way for the development of high-temperature resistant carbon fiber resin composites for use in complicated aeronautical structures.
Preparation and Properties of Double Network Hydrogel with High Compressive Strength
Authors: Kang Bo , Lang Qingli , Tu Jian , Bu Jun , Ren Jingjing , Lyu Bin , Gao Dangge
Published: March 2022

In this work, p–double network (p–DN) hydrogels were formed by the interpenetration of poly(2–acrylamide–2–methylpropanesulfonic acid–copolymer– acrylamide) microgel and polyacrylamide. The initial viscosity of prepolymer solution before hydrogel polymerization, mechanical properties, temperature and salt resistance of the hydrogels were studied. The results showed that the initial viscosity of the prepolymer was less than 30 mP·s, and the p–DN hydrogel not only exhibited high compressive stress (37.80 MPa), but the compressive strength of p–DN hydrogel could also reach 23.45 MPa after heating at 90 °C, and the compressive strength of p–DN hydrogel could reach 13.32 MPa after soaking for 24 h in the solution of 5W mineralization. In addition, the cyclic loading behavior of hydrogel was studied. The dissipation energy of p–DN hydrogel under 80% strain was 7.89 MJ/m3, which effectively dissipated energy. Meanwhile, p–DN hydrogel maintained its original form while breaking the pressure greater than 30 MPa, indicating excellent plugging performance.
Preparation of Citric Acid-Sewage Sludge Hydrochar and Its Adsorption Performance for Pb(II) in Aqueous Solution
Authors: Huang Yangpeng , Shen Dekui , Wang Zhanghong
Published: March 2022

In order to seek the value-added utilization method of sewage sludge and develop low-cost and high-efficient adsorbents, a hydrochar was prepared by the co-hydrothermal carbonization of sewage sludge and citric acid and then characterized. The differences in Pb(II) adsorption performance between the citric acid–sewage sludge hydrochars (AHC) and the hydrochar prepared solely from sewage sludge (SSHC) were also investigated. When citric acid dose ratio (mass ratio of citric acid to dry sewage sludge) is 0.1, the obtained hydrohcar (AHC0.1) has the highest specific surface area (59.95 m2·g−1), the most abundant oxygen-containing functional groups, the lowest pHpzc (5.43), and the highest equilibrium adsorption capacity for Pb(II). The maximum adsorption capacity of AHC0.1 for Pb(II) is 60.88 mg·g−1 (298 K), which is approximately 1.3 times that of SSHC. The potential mechanisms can be electrostatic attraction, co-precipitation, complexation, and cation-π interaction. It was demonstrated that by incorporating citric acid into the hydrothermal carbonization, resource utilization of sewage sludge can be accomplished effectively.
Bio-Based Eucommia ulmoides Gum Composites with High Electromagnetic Interference Shielding Performance
Authors: Kang Hailan , Luo Sen , Du Hongyang , Han Lishuo , Li Donghan , Li Long , Fang Qinghong
Published: March 2022

Herein, high-performance electromagnetic interference (EMI) shielding bio-based composites were prepared by using EUG (Eucommia ulmoides gum) with a crystalline structure as the matrix and carbon nanotube (CNT)/graphene nanoplatelet (GNP) hybrids as the conductive fillers. The morphology of the CNT/GNP hybrids in the CNT/GNP/EUG composites showed the uniform distribution of CNTs and GNPs in EUG, forming a denser filler network, which afforded improved conductivity and EMI shielding effect compared with pure EUG. Accordingly, EMI shielding effectiveness values of the CNT/GNP/EUG composites reached 42 dB in the X-band frequency range, meeting the EMI shielding requirements for commercial products. Electromagnetic waves were mainly absorbed via conduction losses, multiple reflections from interfaces and interfacial dipole relaxation losses. Moreover, the CNT/GNP/EUG composites exhibited attractive mechanical properties and high thermal stability. The combination of excellent EMI shielding performance and attractive mechanical properties render the as-prepared CNT/GNP/EUG composites attractive candidates for various applications.
Sulphate Corrosion Mechanism of Ultra-High-Performance Concrete (UHPC) Prepared with Seawater and Sea Sand
Authors: Sun Xin , Li Tianyu , Shi Fangying , Liu Xiaoyan , Zong Yingxia , Hou Baorong , Tian Huiwen
Published: March 2022

The lack of river sand is becoming increasingly serious. In this study, we consider how to use sea sand to prepare innovative construction and building materials with excellent mechanical and durability properties. Sulphate corrosion causes expansion, cracking and spalling of concrete, resulting in the reduction or even loss of concrete strength and cementation force. In this paper, artificial seawater, sea sand, industrial waste, steel fiber and polycarboxylate superplasticizer were used to prepare ultra-high-performance polymer cement mortar (SSUHPC), and the sulphate corrosion mechanism was investigated. The strength and cementation force of mortar on the SSUHPC surface decreased and flaked off with the development of sulphate erosion, and the steel fiber rusted and fell off. A 3D model was established based on X-ray computed tomography (X-CT), and the results showed that SSUHPC maintained excellent internal structural characteristics despite severe sulphate erosion on the surface. Mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were adopted to investigate the sulphate corrosion mechanism of SSUHPC. We found a transition zone within 1–5 mm of the surface of SSUHPC. The Vickers hardness of mortar in this area was increased by 5~15%, and the porosity was reduced to 3.8489%. Obvious structural damage did not occur in this area, but a high content of gypsum appeared. UHPC prepared with seawater sea sand was found to have better sulphate resistance than that prepared with freshwater river sand, which supports the development and utilization of sea sand in concrete.
Additive Manufacturing with Thermoplastic Collagen
Authors: Klüver Enno , Baltzer Marit , Langer Axel , Meyer Michael
Published: March 2022

Thermoplastic collagen is a partially denatured collagen powder which can be processed by thermoplastic methods such as extrusion and injection molding, but was hitherto not adapted for the use in additive manufacturing (AM) techniques. This paper describes the first successful application of collagen/water/glycerol mixtures in an AM process using a BioScaffolder 3.2 from GeSiM mbH. Strands of molten collagen were deposited onto a building platform forming differently shaped objects. The collagen melt was characterized rheologically and optimal processing conditions were established. The technique includes the use of supporting structures of PLA/wood composite for samples with complex geometry as well as post-processing steps such as the removal of the supporting structure and manual surface smoothing. The manufactured objects are characterized concerning water solubility, swelling behavior and compressibility. Possible applications are in the non-medical sector and include collagen-based pet food or customized organ models for medical training.
The Use of Bilberry Leaves (Vaccinium myrtillus L.) as an Efficient Adsorbent for Cationic Dye Removal from Aqueous Solutions
Authors: Mosoarca Giannin , Vancea Cosmin , Popa Simona , Dan Mircea , Boran Sorina
Published: March 2022

In this study, a new lignocellulosic bioadsorbent, bilberry (Vaccinium myrtillus L.) leaves powder, was used to remove the methylene blue dye from aqueous solutions. The characterization of the adsorbent was performed by FTIR, SEM and color analysis. The influence of pH, contact time, adsorbent dose, initial dye concentration, temperature and ionic strength on the adsorption process were followed. Equilibrium, kinetic, and thermodynamic studies were conducted in order to understand the adsorption process mechanism. Process optimization was performed using the Taguchi method. Sips isotherm and general order kinetic model characterize the adsorption process. The maximum adsorption capacity, 200.4 (mg g−1), was better compared with other similar bioadsorbents. Thermodynamic parameters indicated that the adsorption process is spontaneous, favorable and endothermic and also that physisorption is involved in the process. The factor with the highest influence on the dye removal process was pH, followed by contact time, temperature, adsorbent dose, ionic strength and initial dye concentration. The obtained results revealed that the bioadsorbent material based on bilberry (Vaccinium myrtillus L.) leaves is highly efficient for cationic dyes removal from aqueous solutions.
Cytotoxicity, Colour Stability and Dimensional Accuracy of 3D Printing Resin with Three Different Photoinitiators
Authors: Kim Gi-Tae , Go Hye-Bin , Yu Jae-Hun , Yang Song-Yi , Kim Kwang-Mahn , Choi Sung-Hwan , Kwon Jae-Sung
Published: March 2022

Biocompatibility is important for the 3D printing of resins used in medical devices and can be affected by photoinitiators, one of the key additives used in the 3D printing process. The choice of ingredients must be considered, as the toxicity varies depending on the photoinitiator, and unreacted photoinitiator may leach out of the polymerized resin. In this study, the use of ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate (TPO-L) as a photoinitiator for the 3D printing of resin was considered for application in medical device production, where the cytotoxicity, colour stability, dimensional accuracy, degree of conversion, and mechanical/physical properties were evaluated. Along with TPO-L, two conventional photoinitiators, phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (BAPO) and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO), were considered. A total of 0.1 mol% of each photoinitiator was mixed with the resin matrix to prepare a resin mixture for 3D printing. The specimens were printed using a direct light processing (DLP) type 3D printer. The 3D-printed specimens were postprocessed and evaluated for cytotoxicity, colour stability, dimensional accuracy, degree of conversion, and mechanical properties in accordance with international standards and the methods described in previous studies. The TPO-L photoinitiator showed excellent biocompatibility and colour stability and possessed with an acceptable dimensional accuracy for use in the 3D printing of resins. Therefore, the TPO-L photoinitiator can be sufficiently used as a photoinitiator for dental 3D-printed resin.
Ionic Liquid Agar–Alginate Beads as a Sustainable Phenol Adsorbent
Authors: Yasir Nihal , Khan Amir Sada , Hassan Muhammad Faheem , Ibrahim Taleb H. , Khamis Mustafa I. , Nancarrow Paul
Published: March 2022

Cleaning wastewater containing low concentrations of phenolic compounds is a challenging task. In this work, agar–alginate beads impregnated with trihexyltetradecylphosphonium bromide ([P66614][Br]) ionic liquid adsorbent were synthesized as a potential adsorbent for such applications. FTIR, TGA, SEM, EDX and PZC studies were performed to characterize and understand the physicochemical properties of the adsorbent. The Fourier transformation infrared spectroscopy (FTIR) study showed that [P66614][Br] ionic liquid was effectively incorporated into the agar–alginate structure. TGA and SEM confirmed comparative enhanced thermal stability and porous surface, respectively. Chemical reaction rate-altering parameters, i.e., pH, contact time, initial phenol concentration and temperature, are optimized at highest phenol removal. It was found that the maximum phenol adsorption capacity and highest removal efficiency by the adsorbent occurred at pH 2, initial phenol concentration of 150 mg/L, beads dosage of 6 mg/mL and contact time of 2 h with values of 16.28 mg/g and 65.12%, respectively. The pseudo-second order model fitted the adsorption kinetics well, and the Freundlich isotherm model gave the experimental data the best fit. Analysis of thermodynamic data demonstrated that the adsorption process is fundamentally exothermic in nature, and low temperature favors spontaneity of the chemical reaction. Regeneration studies indicated that the adsorbent can at least be used for four cycles in such applications without any considerable loss in adsorption efficiency.
Mechanical Behavior of Polyethylene Pipes under Strike-Slip Fault Movements
Authors: Li Lin , Qiao Liang , Fan Junming , Zhang Yi
Published: March 2022

The present paper addresses the mechanical behaviors and failure mechanisms of buried polyethylene (PE) pipes crossing active strike slip tectonic faults based on numerical simulation of the nonlinear response of the soil-pipeline system. The developed finite element (FE) model is first verified through comparing the simulation results with those from large-scale tests and good agreement between simulation and experimental measurements is obtained. The FE model is then applied to investigate the effects of fault crossing angle, pipe and soil properties on the mechanical behavior of PE pipe. The results indicate that the PE pipe crossing negative fault angles is primarily subjected to compression and bending, thus exhibits the phenomenon of buckling. With the increase of crossing angle, there is an increase of the axial strain and the maximum Mises stress in the buckled cross section, and a decrease of the distance between the buckling position and the fault plane. While for positive crossing angles, the PE pipe is mainly subjected to tension and relatively small bending. Increasing the crossing angle causes an increase in bending strain and a decrease in the axial strain. In addition, when the fault moving speed is slower, the axial strain and bending strain are larger, whereas the maximum Mises stress in the buckled cross section and the distance between the buckled position and the fault plane are reduced. Furthermore, the most severe deformation of the pipe is observed when it is buried in the sandy soil, followed by cohesive soil and loess soil.
Stress Field Approach for Prediction of End Concrete Cover Separation in RC Beams Strengthened with FRP Reinforcement
Authors: Zhou Binbin , Wu Ruo-Yang , Yin Shiping
Published: March 2022

End concrete cover separation is one of the most common failure modes for RC beams strengthened with external FRP reinforcement. The premature failure mode significantly restricts the application of FRP materials and could incur serious safety problems. In this paper, an innovative stress field-based analytical approach is proposed to assess the failure strength of end concrete cover separation and the conventional plane-section analysis is extended to evaluate the corresponding carrying capacity of FRP-strengthened RC beams. First, the dowel action of reinforcement and the induced concrete splitting, reflecting the interaction between concrete, steel and FRP, are considered in establishing the geometrical relationships of stress field for cracked concrete block. Then, the cracking angle and innovative failure criterion, considering the arrangement of steel and FRP reinforcement and cracking status of concrete and its softening effect, are derived to predict the occurrence of concrete cover separation and related mixed modes of debonding failure. Subsequently, an extended sectional analytical approach, in which the components of effective tensile strain of FRP resulted from flexural and shear actions are both considered, is presented to evaluate the carrying capacity of strengthened beams. Finally, the proposed calculational model is effectively validated by experimental results available in the literature.
Effect of Ultrasound Treatment on Barrier Changes of Polymers before and after Exposure to Food Simulants
Authors: Ščetar Mario , Daniloski Davor , Tinjić Mirela , Kurek Mia , Galić Kata
Published: March 2022

In this study, we investigated the impact of ultrasound treatment on barrier properties of linear low-density polyethylene (LLDPE) and acrylic/poly(vinylidene chloride) polypropylene (PPAcPVDC)-coated pouches intended for food packaging before and after exposure to food simulants. Packaging pouches were filled with two food simulants, namely ethanol (10% (v/v)) and acetic acid (3% (w/v)), in order to simulate food–packaging interaction and possible compound migration from packaging materials. Samples were subjected to an ultrasound water bath treatment for 5 min, 15 min, and 30 min at 60 °C (±2 °C) and with an amplitude of 100% as an equivalent to the heat-treatment conditions combined with an ultrasound effect. Furthermore, the effect of temperature on the polymer barrier (water vapour and oxygen permeability) properties was tested at 20 °C, 40 °C, and 60 °C. Results showed that PPAcPVDC possessed better properties of water vapour permeability and oxygen permeability properties to LLDPE. Statistical analyses showed a significant (p < 0.001) impact of ultrasound treatment on the overall migration value, regardless of the food simulant used.
Alumina Manufactured by Fused Filament Fabrication: A Comprehensive Study of Mechanical Properties and Porosity
Authors: Truxová Veronika , Šafka Jiří , Sobotka Jiří , Macháček Jakub , Ackermann Michal
Published: March 2022

This article deals with a comprehensive study of the processing and mechanical properties of the ceramic material Al2O3 on Fused Filament Fabrication technology (FFF). It describes the basic input analyses of the material, such as TGA, FTIR, and MVR. These analyses enabled the design and testing of process parameters for the 3D printing of parts. The article also presents the post-processes, including the technological parameters required to finalize parts made from this material, i.e., chemical debinding in acetone at elevated temperatures + thermal debinding and sintering. The microhardness was measured on the processed samples, depending on the density of the inner filling. The resulting hardness had an almost linear relationship between the percentage of filler (20–40–60–80–100%) and the resulting microhardness (1382–2428 HV10). Flexural strength was also measured on the test specimens with different degrees of internal filling (80–90–100%). However, inner filling do not affect the flexural strength (316.12–327.84–331.61 MPa). The relative density of the final parts was measured on a ZEISS METROTOM 1500 CT machine and reached 99.54%.
Poly 3-Hydroxybutyrate 4-hydroxybutyrate (P34HB) as a Potential Polymer for Drug-Eluting Coatings on Metal Coronary Stents
Authors: Jian Yihui , Zhu Yufang
Published: March 2022

Drug-eluting stents (DES) are a main interventional therapeutic instrument to treat coronary diseases. Degradable polymers such as polylactic acid (PLA) for coatings that only degrade into small molecules in human bodies have been developed for coating polymers, but most coatings often lack ductility and can be easily peeled off from the stents after balloon expansion. In this study, biodegradable poly 3-hydroxybutyrate 4-hydroxybutyrate (P34HB) with good ductility was proposed to be a latent polymer for drug-eluting coatings on the stents. Using P34HB-1 (4HB% = 1%wt, Mw: 225,000) and P34HB-10 (4HB% = 10%wt, Mw: 182,000) as two candidates, both P34HB-1 and P34HB-10 exhibited excellent solubility in CHCl3. Their drug solutions remained highly stable and did not become turbid over a period of 48 h, and were conducive to batch preparation of uniform drug coatings. Drug coatings made by both P34HB-1 and P34HB-10 on the stents were almost complete before and after dilation by balloon owing to their excellent adhesion and extrusion resistance properties. Furthermore, both P34HB-1 and P34HB-10 had excellent biocompatibility in cytotoxicity and hemolysis tests. However, P34HB-1 drug coatings showed better drug release control than P34HB-10 drug coatings and Firebird2®, indicating that P34HB-1 is more suitable for a latent coating polymer of coronary stents.
Exploration of the Adsorption Reduction of the Pigment Aggregates Strength under the Effect of Surfactants in Water-Dispersion Paints
Authors: Dyuryagina Antonina , Lutsenko Aida , Ostrovnoy Kirill , Tyukanko Vitaliy , Demyanenko Alexandr , Akanova Meiramgul
Published: March 2022

This article presents the results of studying the disaggregation of titanium dioxide in water-dispersion compositions based on an acrylic film-forming agent under the action of a surfactant. The possibility of using polyether siloxane copolymer (PC) and sodium polyacrylate (NaPA) in paint and varnish compositions as modifying additives of the dispersing effect is proved. The correlation between the dispersing effect of surfactants and the amount of their adsorption on the pigment is proved. NaPA, which provides a greater reduction in adsorption strength, demonstrates a greater dispersing effect than PC. It was found that the larger the size of the aggregates of pigment particles, the greater the disjoining pressure created by the surfactant. An equation is derived that generalizes the cumulative contribution of surfactant concentration and the content of the film-forming agent in suspensions to the average particle diameter of pigment. The introduction of NaPA in the amount of 0.25 g/dm3 into the paint allows the rate of acid corrosion to be reduced by 2 times, the number of pores in the coating to be decreased, and the adhesion of the coating to be significantly increased (by 2 points according to ISO 11845: 2020).
Synthesis and Characterization of Biodegradable Poly(butyl cyanoacrylate) for Drug Delivery Applications
Authors: Keller Benjamin-Luca , Lohmann Claudia A. , Kyeremateng Samuel O. , Fricker Gert
Published: March 2022

Poly(butyl cyanoacrylate) (PBCA) is a biodegradable and biocompatible homopolymer which is used as a carrier matrix for drug delivery systems in the pharmaceutical industry. Typically, polymerization is carried out under aqueous conditions and results in molecular weights are mostly lower than 3000 g/mol due to the instability of the high molecular weight PBCA. However, the stability of polymer excipients is a major prerequisite for drug product development in the pharmaceutical industry. In this work, a reliable polymer synthesis strategy for PBCA was designed to control the molecular weight in a nonaqueous polymerization environment. The anionic polymerization process and the impact of key synthesis parameters were investigated. The results confirmed that the previously postulated depolymerization–repolymerization process (DPRP) in the literature can be used to tailor the molecular weight of PBCA. The amount of sodium methoxide present during the polymerization proved to be the key parameter to control the DPRP and the molecular weight as desired. In addition, it was discovered that end-capping the PBCA chain suppressed the DPRP and prevented monomer release by depriving the PBCA of its living character. Thus, neat PBCA polymer with varying molecular weights determined by Advanced Polymer Chromatography™ as well as end-capped PBCA were synthesized, and the improvement of the chemical and shelf-life stability were confirmed using NMR.
Mechanical Properties of Animal Tendons: A Review and Comparative Study for the Identification of the Most Suitable Human Tendon Surrogates
Authors: Burgio Vito , Civera Marco , Rodriguez Reinoso Mariana , Pizzolante Elena , Prezioso Simona , Bertuglia Andrea , Surace Cecilia
Published: March 2022

The mechanical response of a tendon to load is strictly related to its complex and highly organized hierarchical structure, which ranges from the nano- to macroscale. In a broader context, the mechanical properties of tendons during tensile tests are affected by several distinct factors, due in part to tendon nature (anatomical site, age, training, injury, etc.) but also depending on the experimental setup and settings. This work aimed to present a systematic review of the mechanical properties of tendons reported in the scientific literature by considering different anatomical regions in humans and several animal species (horse, cow, swine, sheep, rabbit, dog, rat, mouse, and foal). This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method. The literature research was conducted via Google Scholar, PubMed, PicoPolito (Politecnico di Torino’s online catalogue), and Science Direct. Sixty studies were selected and analyzed. The structural and mechanical properties described in different animal species were reported and summarized in tables. Only the results from studies reporting the strain rate parameter were considered for the comparison with human tendons, as they were deemed more reliable. Our findings showed similarities between animal and human tendons that should be considered in biomechanical evaluation. An additional analysis of the effects of different strain rates showed the influence of this parameter.
A New Camera Calibration Technique for Serious Distortion
Authors: Huang Biao , Zou Shiping
Published: March 2022

A new camera calibration technique based on serious distortion is proposed, which only requires the camera to observe the plane pattern in an arbitrary azimuth. It uses the geometrical imaging principle and radial distortion model to acquire radial lens distortion coefficient and the image coordinate (u0, v0), and then solves the linear equation aiming at the other parameters of the camera. This method has the following characteristics: Firstly, the position of the camera and the plane is arbitrary, and the technique needs only a single observation for plane pattern. Secondly, it is suitable for camera calibration with serious distortion. Thirdly, it does not need expensive ancillary equipment, accurate movement, or lots of photos observed from different orientations. Having been authenticated by computer emulation and actual experiment, the results of the proposed technique have proved to be satisfactory. The research has also paved a new way in camera calibration for further studies.
Contempt for the Whos? or: How to Read Nietzsche Autobiographically after the Death of the Bios
Authors: Swanson Joel
Published: March 2022

This paper examines French philosopher Sarah Kofman’s fractured relationships to her identities as Jew and woman. Active participant in postwar debates surrounding deconstruction and psychoanalysis, acclaimed reader of Freud and Nietzsche, and interlocutor of Derrida, Kofman is today most widely remembered for her autobiographical writings about her childhood as a young Orthodox Jewish girl during the Nazi occupation of Paris. Kofman’s mother sent her to pretend to be the daughter of a Christian woman, which both ensured Kofman’s physical survival and led to an uncanny Freudian doubling of the maternal figure, such that both “Jew” and “Christian” became unstable, mimetic identity categories which Kofman could never again fully inhabit. The paper examines Kofman’s writings on Nietzsche, suggesting that her attempt to absolve the German philosopher of the charges of antisemitism oft leveled against him functioned as a similarly failed and incomplete means of asserting control over her personal identity. If Kofman could demonstrate that Nietzsche was not in fact an antisemite, then she could write herself into the lineage of Continental philosophy and reclaim the stable ancestry she lost during the war. Yet the paper concludes that a counter-narrative running throughout Kofman’s writings suggests an awareness that she could never fully absolve Nietzsche, and therefore that her attempt to claim Nietzsche as a father figure would always fail. The paper thus suggests that the illusion of control and stability epitomized by Kofman’s reading of Nietzsche provides an interpretive thematic to understand the unstable figure of the post-Holocaust Jewish philosopher.
Attributions of Evapotranspiration and Gross Primary Production Changes in Semi-Arid Region: A Case Study in the Water Source Area of the Xiong’an New Area in North China
Authors: Zeng Sidong , Du Hong , Xia Jun , Wu Jian , Yang Linhan
Published: March 2022

Investigating the attributions of evapotranspiration (ET) and gross primary production (GPP) changes is of great importance for regional, sustainable water resources and ecological management in semi-arid regions. Based on the simulation conducted during 2000–2019 by improving water-carbon coupling Distributed Time Variant Gain Model, the trends of ET and GPP were estimated and the driving factors were identified via 10 experimental scenarios in the water source area of the Xiong’an New Area in North China. The results show significant increases both in ET and GPP by 2.4 mm/a and 6.0 gC/m2/a in the region, respectively. At the annual scale, increasing precipitation dominates the ET uptrend. Air temperature, humidity and the interactive effects also contribute to the ET uptrend, and the contributions are 12.8%, 2.0% and 2.3%, respectively, while elevated atmospheric CO2 concentration (eCO2) and solar dimming lead to ET changes of about −7.2% and −12.4%, respectively. For the GPP changes, the increase in GPP is mainly caused by eCO2, increasing precipitation and rising temperature with the contributions of 56.7%, 34.8% and 27.8%, respectively. Solar dimming, humidity and windspeed contribute −6.8%, −4.8% and −3.5% of the GPP changes. Compared to climate change, land use and cover change has smaller effects on both ET and GPP for the few changes in land coverage. At the seasonal scale, ET and GPP increase to a greater extent during the growing season in spring and summer than in autumn and winter. Precipitation, temperature and eCO2 are generally the main causes for ET and GPP changes. Meanwhile, the decreasing humidity and rising temperature are dominant factors for ET and GPP increases, respectively, in winter. Furthermore, solar dimming has strong effects on ET reduction in autumn. The contribution of the interactive effects is much higher on a seasonal scale than annual scale, contributing to considerable decreases in ET and GPP in spring, increases in ET in autumn and winter, and an increase in GPP in winter. This study highlights the importance of considering water-carbon coupling on the attributions of ET and GPP changes and the differentiation of the effects by the abovementioned influential factors at annual and seasonal scales.
Random Forest Classification of Land Use, Land-Use Change and Forestry (LULUCF) Using Sentinel-2 Data—A Case Study of Czechia
Authors: Svoboda Jan , Štych Přemysl , Laštovička Josef , Paluba Daniel , Kobliuk Natalia
Published: March 2022

Land use, land-use change and forestry (LULUCF) is a greenhouse gas inventory sector that evaluates greenhouse gas changes in the atmosphere from land use and land-use change. This study focuses on the development of a Sentinel-2 data classification according to the LULUCF requirements on the cloud-based platform Google Earth Engine (GEE). The methods are tested in selected larger territorial regions (two Czech NUTS 2 units) using data collected in 2018. The Random Forest method was used for classification. In terms of classification accuracy, a combination of these parameters was tested: The Number of Trees (NT), the Variables per Split (VPS) and the Bag Fraction (BF). A total of 450 combinations of different parameters were tested. The highest accuracy classification with an overall accuracy = 89.1% and Cohen’s Kappa = 0.84 had the following combination: NT = 150, VPS = 3 and BF = 0.1. For classification purposes, a mosaic was created using the median method. The resulting mosaic consisted of all Sentinel-2 bands in 10 and 20 m spatial resolution. Altitude values derived from SRTM and NDVI variance values were also included in the classification. These added bands were the most significant in terms of Gini importance.
A Comparative Study of the Landfall Precipitation by Tropical Cyclones ARB 01 (2002) and Luban (2018) near the Arabian Peninsula
Authors: Cui Yusheng , Lü Haibin , Shi Dawei , Xia Chuqi , Dong Changming
Published: March 2022

Considering the high risk of flooding during tropical cyclones (TCs), there is great practical significance in researching and predicting precipitation during TC landfalls. Using NECP FNL reanalysis data and GPM_MERGIR datasets, two TCs with similar trajectories, ARB 01 in 2002 and Luban in 2018, were analyzed. For ARB 01 and Luban, there are separate effects of wind shear at different heights on the development of vertical motion. Meridional wind shear affects the main deviation direction of vertical motion (downshear), while zonal wind shear mainly affects the deviation direction of vertical motion to the left or right of downshear. The divergent configuration of wind promotes the development of vertical motion. The influence of wind speed provided ideal conditions for ARB 01 to generate symmetric precipitation along its path when it made landfall. Additionally, more water vapor support was obtained from the southern Indian Ocean, which enabled ARB 01 to have a larger and broader average precipitation rate after landing.
Affinity Propagation Based on Structural Similarity Index and Local Outlier Factor for Hyperspectral Image Clustering
Authors: Ge Haimiao , Wang Liguo , Pan Haizhu , Zhu Yuexia , Zhao Xiaoyu , Liu Moqi
Published: March 2022

In hyperspectral remote sensing, the clustering technique is an important issue of concern. Affinity propagation is a widely used clustering algorithm. However, the complex structure of the hyperspectral image (HSI) dataset presents challenge for the application of affinity propagation. In this paper, an improved version of affinity propagation based on complex wavelet structural similarity index and local outlier factor is proposed specifically for the HSI dataset. In the proposed algorithm, the complex wavelet structural similarity index is used to calculate the spatial similarity of HSI pixels. Meanwhile, the calculation strategy of the spatial similarity is simplified to reduce the computational complexity. The spatial similarity and the traditional spectral similarity of the HSI pixels jointly constitute the similarity matrix of affinity propagation. Furthermore, the local outlier factors are applied as weights to revise the original exemplar preferences of the affinity propagation. Finally, the modified similarity matrix and exemplar preferences are applied, and the clustering index is obtained by the traditional affinity propagation. Extensive experiments were conducted on three HSI datasets, and the results demonstrate that the proposed method can improve the performance of the traditional affinity propagation and provide competitive clustering results among the competitors.
Estimating Long-Term Average Carbon Emissions from Fires in Non-Forest Ecosystems in the Temperate Belt
Authors: Ostroukhov Andrey , Klimina Elena , Kuptsova Viktoriya , Naito Daisuke
Published: March 2022

Research into pyrogenic carbon emissions in the temperate belt of the Russian Federation has traditionally focused on the impact of forest fires. Nevertheless, ecosystems in which wildfires also make a significant contribution to anthropogenic CO2 emissions are poorly studied. We evaluated the carbon emissions of fires in the non-forest ecosystems of the Middle Amur Lowland, in the Khabarovsk Territory of the Russian Federation. Our study is based on long-term Earth remote sensing data of medium spatial resolution (Landsat 5, 7, and 8) and expeditionary studies (2018–2021). The assessment of carbon directly emitted from wildfires in meadow and meadow–mire temperate ecosystems in the Middle Amur lowland shows that specific emissions from such ecosystems vary, from 1.09 t/ha in dwarf shrub–sphagnum and sphagnum–ledum and sedge–reed fens to 6.01 t/ha in reed–forb, forb, reed, and sedge meadows. Meanwhile, carbon emissions specifically from fires in meadow and meadow–mire ecosystems are less significant—often an order of magnitude less than carbon emissions from forest fires (which reach 37 tC/ha). However, due to their high frequency and the large areas of land burned annually, the total carbon emissions from such fires are comparable to annual emissions from fires in forested areas. The results obtained show that the inadequacy of the methods used in the automatic mapping of burns leads to a significant underestimation of the area of grassland fires and carbon emissions from non-forest fires.
Accurate Matching of Invariant Features Derived from Irregular Curves
Authors: Liu Huajun , Yin Shuang , Sui Haigang , Yang Qingye , Lei Dian , Yang Wei
Published: March 2022

High-quality feature matching is a critical prerequisite in a wide range of applications. Most contemporary methods concentrate on detecting keypoints or line features for matching, which have achieved adequate results. However, in some low-texture environments where these features are both lacking, previously used approaches may result in an insufficient number of matches. Besides, in repeated-texture environments, feature matching is also a challenging task. As a matter of fact, there exist numerous irregular curves that can be detected in all kinds of images, including low-texture and repeated-texture scenes, which inspires us to move a step further and dig into the research of curves. In this paper, we propose an accurate method to match invariant features from irregular curves. Our method consists of two stages, the first of which is to match the curves as accurately as possible by an elaborate three-step matching strategy. The second is to extract the matching features with the presented self-adaptive curve fitting approach. Experiments have shown that the matching performances of our features in ordinary scenes are comparable to previous keypoints. Particularly, our features can outperform the keypoints in low-texture and repeated-texture scenes.
Extracting Disaster-Related Location Information through Social Media to Assist Remote Sensing for Disaster Analysis: The Case of the Flood Disaster in the Yangtze River Basin in China in 2020
Authors: Yang Tengfei , Xie Jibo , Li Guoqing , Zhang Lianchong , Mou Naixia , Wang Huan , Zhang Xiaohan , Wang Xiaodong
Published: March 2022

Social media texts spontaneously produced and uploaded by the public contain a wealth of disaster information. As a supplementary data source for remote sensing, they have played an important role in disaster reduction and emergency response in recent years. However, social media also has certain flaws, such as insufficient location information, etc. This affects the efficiency of combining these data with remote sensing data. For flood disasters in particular, extensively flooded areas limit the distribution of social media data, which makes it difficult for these data to function as they should. In this paper, we propose a disaster reduction framework to solve these problems. We first used an approach that was based on search engine and lexical rules to automatically extract disaster-related location information from social media texts. Then, we combined the extracted information with the upload location of social media itself to construct location-pointing relationships. These relationships were used to build a new social network, which can be used in combination with remote sensing images for disaster analysis. The analysis integrated the advantages of social media and remote sensing. It can not only provide macro disaster information in the study area but can also assist in evaluating the disaster situation in different flooded areas from the perspective of public observation. In addition, the timeliness of social media data also improved the continuity and situational awareness of flood monitoring. A case study of the flood disaster in the Yangtze River Basin in China in 2020 was used to verify the effectiveness of the method described in this paper.