bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Secondary Cold Reduction Rates on Microstructure, Texture and Earing Behavior of Double Reduction Tinplate
Authors: Tian Peng , Liao Luhai , Zhu Guoming , Kang Yonglin
Published: July 2021

In order to evaluate the effect of secondary cold reduction rate on the drawing performance of double reduction tinplate and explain the mechanism, a detailed investigation into the microstructural characterization, dissolved carbon atoms, texture characterization by an X-ray powder diffractometer (XRD) and electron backscatter diffraction (EBSD), and earing behavior were carried out with different secondary cold reduction rates of 15%, 20% and 25% for double reduction tinplate. The experimental results indicate that 15% secondary cold reduction rate could obtain a better drawing performance because there are no holes and cracks at the microstructure, and the content of dissolved carbon atom is relatively low; at the same time, it has a better texture distribution and low earing coefficient.
Calibration of Drucker–Prager Cap Constitutive Model for Ceramic Powder Compaction through Inverse Analysis
Authors: Buljak Vladimir , Baivier-Romero Severine , Kallel Achraf
Published: July 2021

Phenomenological plasticity models that relate relative density to plastic strain are frequently used to simulate ceramic powder compaction. With respect to the form implemented in finite element codes, they need to be modified in order to define governing parameters as functions of relative densities. Such a modification increases the number of constitutive parameters and makes their calibration a demanding task that involves a large number of experiments. The novel calibration procedure investigated in this paper is based on inverse analysis methodology, centered on the minimization of a discrepancy function that quantifies the difference between experimentally measured and numerically computed quantities. In order to capture the influence of sought parameters on measured quantities, three different geometries of die and punches are proposed, resulting from a sensitivity analysis performed using numerical simulations of the test. The formulated calibration protocol requires only data that can be collected during the compaction test and, thus, involves a relatively smaller number of experiments. The developed procedure is tested on an alumina powder mixture, used for refractory products, by making a reference to the modified Drucker–Prager Cap model. The assessed parameters are compared to reference values, obtained through more laborious destructive tests performed on green bodies, and are further used to simulate the compaction test with arbitrary geometries. Both comparisons evidenced excellent agreement.
Thermodynamic Description of Dilution and Dissolution Processes in the MgCl2−CsCl−H2O Ternary System
Authors: Baranauskaite Valeriia , Belysheva Maria , Pestova Olga , Anufrikov Yuri , Skripkin Mikhail , Kondratiev Yuri , Khripun Vassily
Published: July 2021

Thermodynamic data on the properties of the water-based electrolyte systems are very valuable for fundamental physical chemistry and for industrial applications. The missing data both on the dilution and dissolution enthalpies for the ternary CsCl−MgCl2−H2O mixed electrolyte system were investigated by means of the calorimetry method. The dilution calorimetry was performed at 298 K for the set of solutions from diluted to concentrated at constant ratio Cs+/Mg2+=1.8. The relative partial molar enthalpies, ideal, total, and excess ones were calculated. By means of the dissolution calorimetry, the standard enthalpies of formation, the enthalpies, and entropies for the double salt formation from simple salts were evaluated. The results obtained indicate that entropy as the major factor affecting the formation of the joint compound, both in the liquid and solid phases. These data can be implemented in thermodynamic databases and allow for accurate thermodynamic calculations for the salts extraction from natural water sources and for its possible application as thermochemical energy storage.
Analytical Solution of the Non-Stationary Heat Conduction Problem in Thin-Walled Products during the Additive Manufacturing Process
Authors: Mukin Dmitrii , Valdaytseva Ekaterina , Turichin Gleb
Published: July 2021

The work is devoted to the development of a model for calculating transient quasiperiodic temperature fields arising in the direct deposition process of thin walls with various configurations. The model allows calculating the temperature field, thermal cycles, temperature gradients, and the cooling rate in the wall during the direct deposition process at any time. The temperature field in the deposited wall is determined based on the analytical solution of the non-stationary heat conduction equation for a moving heat source, taking into account heat transfer to the environment. Heat accumulation and temperature change are calculated based on the superposition principle of transient temperature fields resulting from the heat source action at each pass. The proposed method for calculating temperature fields describes the heat-transfer process and heat accumulation in the wall with satisfactory accuracy. This was confirmed by comparisons with experimental thermocouple data. It takes into account the size of the wall and the substrate, the change in power from layer to layer, the pause time between passes, and the heat-source trajectory. In addition, this calculation method is easy to adapt to various additive manufacturing processes that use both laser and arc heat sources.
Antibacterial Properties of a Honeycomb-like Pattern with Cellulose Acetate and Silver Nanoparticles
Authors: Hurtuková Klaudia , Fajstavrová Klára , Rimpelová Silvie , Vokatá Barbora , Fajstavr Dominik , Kasálková Nikola Slepičková , Siegel Jakub , Švorčík Václav , Slepička Petr
Published: July 2021

This study involved the preparation and characterization of structures with a honeycomb-like pattern (HCP) formed using the phase separation method using a solution mixture of chloroform and methanol together with cellulose acetate. Fluorinated ethylene propylene modified by plasma treatment was used as a suitable substrate for the formation of the HCP structures. Further, we modified the HCP structures using silver sputtering (discontinuous Ag nanoparticles) or by adding Ag nanoparticles in PEG into the cellulose acetate solution. The material morphology was then determined using atomic force microscopy (AFM) and scanning electron microscopy (SEM), while the material surface chemistry was studied using energy dispersive spectroscopy (EDS) and wettability was analyzed with goniometry. The AFM and SEM results revealed that the surface morphology of pristine HCP with hexagonal pores changed after additional sample modification with Ag, both via the addition of nanoparticles and sputtering, accompanied with an increase in the roughness of the PEG-doped samples, which was caused by the high molecular weight of PEG and its gel-like structure. The highest amount (approx. 25 at %) of fluorine was detected using the EDS method on the sample with an HCP-like structure, while the lowest amount (0.08%) was measured on the PEG + Ag sample, which revealed the covering of the substrate with biopolymer (the greater fluorine extent means more of the fluorinated substrate is exposed). As expected, the thickness of the Ag layer on the HCP surface depended on the length of sputtering (either 150 s or 500 s). The sputtering times for Ag (150 s and 500 s) corresponded to layers with heights of about 8 nm (3.9 at % of Ag) and 22 nm (10.8 at % of Ag), respectively. In addition, we evaluated the antibacterial potential of the prepared substrate using two bacterial strains, one Gram-positive of S. epidermidis and one Gram-negative of E. coli. The most effective method for the construction of antibacterial surfaces was determined to be sputtering (150 s) of a silver nanolayer onto a HCP-like cellulose structure, which proved to have excellent antibacterial properties against both G+ and G− bacterial strains.
Steel Corrosion Behavior of Reinforced Calcium Aluminate Cement-Mineral Additions Modified Mortar
Authors: Wang Zhongping , Chen Yuting , Zhu Zheyu , Peng Xiang , Wu Kai , Xu Linglin
Published: July 2021

Mineral additions can eliminate the conversion in calcium aluminate hydrates and thus inhibit the future strength retraction of calcium aluminate cement (CAC). However, the impacts of these additions on the protection capacity of CAC concrete in relation to the corrosion of embedded steel reinforcement remains unclear. This paper focused on the corrosion behavior of steel reinforcement in slag, limestone powder, or calcium nitrate-modified CAC mortars via XRD and electrochemical methods (corrosion potential, electrochemical impedance, and linear polarization evaluation). The results indicate that strätlingite (C2ASH8), which is formed in slag-modified CAC, has poor chloride-binding ability, leading to decline in corrosion resistance of the steel reinforcement. The electrochemical parameters of specimens immersed in NaCl solution suddenly drop at 14 days, which is 28 days earlier than that of the references. In contrast, the Ca2[Al(OH)6]20.5CO3OH·H2O (CaAl·CO32−-LDH) and 3CaO·Al2O3·Ca(NO3)2·12H2O (NO3-AFm) in limestone powder and calcium nitrate-modified CAC mortar show great chloride-binding ability, thereby improving the corrosion resistance of the steel reinforcement. The electrochemical parameters of specimens modified with calcium nitrate maintain a slow decreasing trend within 90 days.
Impact of Humidity and Temperature on the Stability of the Optical Properties and Structure of MAPbI3, MA0.7FA0.3PbI3 and (FAPbI3)0.95(MAPbBr3)0.05 Perovskite Thin Films
Authors: Tumusange Marie Solange , Subedi Biwas , Chen Cong , Junda Maxwell M. , Song Zhaoning , Yan Yanfa , Podraza Nikolas J.
Published: July 2021

In situ real-time spectroscopic ellipsometry (RTSE) measurements have been conducted on MAPbI3, MA0.7FA0.3PbI3, and (FAPbI3)0.95(MAPbBr3)0.05 perovskite thin films when exposed to different levels of relative humidity at given temperatures over time. Analysis of RTSE measurements track changes in the complex dielectric function spectra and structure, which indicate variations in stability influenced by the underlying material, preparation method, and perovskite composition. MAPbI3 and MA0.7FA0.3PbI3 films deposited on commercial fluorine-doped tin oxide coated glass are more stable than corresponding films deposited on soda lime glass directly. (FAPbI3)0.95(MAPbBr3)0.05 films on soda lime glass showed improved stability over the other compositions regardless of the substrate, and this is attributed to the preparation method as well as the final composition.
Effect of Grinding and the Mill Type on Magnetic Properties of Carboxylated Multiwall Carbon Nanotubes
Authors: Jamrozik Agnieszka , Przewoznik Janusz , Krysiak Sonia , Korecki Jozef , Trykowski Grzegorz , Małolepszy Artur , Stobiński Leszek , Burda Kvetoslava
Published: July 2021

The influence of the grinding process on the magnetic properties of as prepared and functionalized multiwall carbon nanotubes (MWCNTs) is presented. We have observed that 3 h mechanical grinding at 400 rpm in contrast to functionalization does not remove the iron contamination from MWCNTs. However, it changes the Fe chemical states. The magnetic properties of iron nanoparticles (Fe-NPs) embedded in the carbon matrix of MWCNTs have been analyzed in detail. We have proven that single-domain non-interacting Fe(C,O)-NPs enriched in the Fe3C phase (~10 nm) enclosed inside these nanotubes are responsible for their magnetic properties. Mechanical grinding revealed a unique impact of -COOH groups (compared to -COONH4 groups) on the magnetism of functionalized MWCNTs. In MWCNT-COOH ground in a steel mill, the contribution of the Fe2O3 and α-Fe phases increased while the content of the magnetically harder Fe3C phase decreased. This resulted in a 2-fold coercivity (Hc) decrease and saturation magnetization (MS) increase. A 2-fold remanence (Mr) decrease in MWCNT-COOH ground in an agate mill is related to the modified Fe(C,O)-NP magnetization dynamics. Comparison of the magnetostatic exchange and effective anisotropy length estimated for Fe(C,O)-NPs allows concluding that the anisotropy energy barrier is higher than the magnetostatic energy barrier. The enhanced contribution of surface anisotropy to the effective anisotropy constant and the unique effect of the -COOH groups on the magnetic properties of MWCNTs are discussed. The procedure for grinding carboxylated MWCNTs with embedded iron nanoparticles using a steel mill has a potential application for producing Fe-C nanocomposites with desired magnetic properties.
Influence of Li2O Incrementation on Mechanical and Gamma-Ray Shielding Characteristics of a TeO2-As2O3-B2O3 Glass System
Authors: Almuqrin Aljawhara H. , Hanfi Mohamed Y. , Sayyed M. I. , Mahmoud K. G. , Al-Ghamdi Hanan , Aloraini Dalal Abdullah
Published: July 2021

According to the Makishema–Mackenzie model assumption, the dissociation energy and packing density for a quaternary TeO2-As2O3-B2O3-Li2O glass system were evaluated. The dissociation energy rose from 67.07 to 71.85 kJ/cm3, whereas the packing factor decreased from 16.55 to 15.21 cm3/mol associated with the replacement of TeO2 by LiO2 compounds. Thus, as a result, the elastic moduli (longitudinal, shear, Young, and bulk) were enhanced by increasing the LiO2 insertion. Based on the estimated elastic moduli, mechanical properties such as the Poisson ratio, microhardness, longitudinal velocity, shear velocity, and softening temperature were evaluated for the investigated glass samples. In order to evaluate the studied glasses’ gamma-ray shield capacity, the MCNP-5 code, as well as a theoretical Phy-X/PSD program, were applied. The best shielding capacity was achieved for the glass system containing 25 mol% of TeO2, while the lowest ability was obtained for the glass sample with a TeO2 concentration of 5 mol%. Furthermore, a correlation between the studied glasses’ microhardness and linear attenuation coefficient was performed versus the LiO2 concentration to select the glass sample which possesses a suitable mechanical and shielding capacity.
Modelling Oil Price with Lie Algebras and Long Short-Term Memory Networks
Authors: Bildirici Melike , Bayazit Nilgun Guler , Ucan Yasemen
Published: July 2021

In this paper, we propose hybrid models for modelling the daily oil price during the period from 2 January 1986 to 5 April 2021. The models on S2 manifolds that we consider, including the reference ones, employ matrix representations rather than differential operator representations of Lie algebras. Firstly, the performance of LieNLS model is examined in comparison to the Lie-OLS model. Then, both of these reference models are improved by integrating them with a recurrent neural network model used in deep learning. Thirdly, the forecasting performance of these two proposed hybrid models on the S2 manifold, namely Lie-LSTMOLS and Lie-LSTMNLS, are compared with those of the reference LieOLS and LieNLS models. The in-sample and out-of-sample results show that our proposed methods can achieve improved performance over LieOLS and LieNLS models in terms of RMSE and MAE metrics and hence can be more reliably used to assess volatility of time-series data.
Phosphate Adsorption from Aqueous Solution Using Electrospun Cellulose Acetate Nanofiber Membrane Modified with Graphene Oxide/Sodium Dodecyl Sulphate
Authors: Amin Nur Ain Atiqah Mohd , Mokhter Mohd Akmali , Salamun Nurrulhidayah , Wan Mahmood Wan M. Asyraf
Published: July 2021

Eutrophication and water pollution caused by a high concentration of phosphate are two concerning issues that affect water quality worldwide. A novel cellulose-based adsorbent, cellulose acetate/graphene oxide/sodium dodecyl sulphate (CA/GO/SDS), was developed for water treatment. A 13% CA solution in a mixture of acetone:dimethylacetamide (2:1) has been electrospun and complexed with a GO/SDS solution. The field emission scanning electron microscope (FESEM) showed that the CA membrane was pure white, while the CA/GO/SDS membrane was not as white as CA and its colour became darker as the GO content increased. The process of phosphate removal from the solutions was found to be aided by the hydroxyl groups on the surface of the CA modified with GO/SDS, as shown by infrared spectroscopy. An optimization condition for the adsorption process was studied by varying pH, immersion time, and the mass of the membrane. The experimental results from phosphate adsorption showed that CA/GO/SDS had an excellent pH adaptability, with an optimum pH of 7, and maximum removal (>87.0%) was observed with a membrane mass of 0.05 g at an initial concentration of 25 mg L−1. A kinetic study revealed that 180 min of contact time could adsorb about 87.2% of phosphate onto the CA/GO/SDS membrane. A typical pseudo-second-order kinetic model successfully portrayed the kinetic sorption of phosphate, and the adsorption equilibrium data were well-correlated with the Langmuir adsorption model, suggesting the monolayer coverage of adsorbed molecules.
Non-Isothermal Reduction Kinetics of Iron Ore Fines with Carbon-Bearing Materials
Authors: Hammam Abourehab , Cao Yi , El-Geassy Abdel-Hady A. , El-Sadek Mohamed H. , Li Ying , Wei Han , Omran Mamdouh , Yu Yaowei
Published: July 2021

This study investigates the non-isothermal reduction of iron ore fines with two different carbon-bearing materials using the thermogravimetric technique. The iron ore fines/carbon composites were heated from room temperature up to 1100 °C with different heating rates (5, 10, 15, and 20 °C/min) under an argon atmosphere. The effect of heating rates and carbon sources on the reduction rate was intensively investigated. Reflected light and scanning electron microscopes were used to examine the morphological structure of the reduced composite. The results showed that the heating rates affected the reduction extent and the reduction rate. Under the same heating rate, the rates of reduction were relatively higher by using charcoal than coal. The reduction behavior of iron ore-coal was proceeded step wisely as follows: Fe2O3 → Fe3O4 → FeO → Fe. The reduction of iron ore/charcoal was proceeded from Fe2O3 to FeO and finally from FeO to metallic iron. The reduction kinetics was deduced by applying two different methods (model-free and model-fitting). The calculated activation energies of Fe2O3/charcoal and of Fe2O3/coal are 40.50–190.12 kJ/mol and 55.02–220.12 kJ/mol, respectively. These indicated that the reduction is controlled by gas diffusion at the initial stages and by nucleation reaction at the final stages.
Comparative Study of the Metallurgical Quality of Primary and Secondary AlSi10MnMg Aluminium Alloys
Authors: Bakedano Asier , Niklas Andrea , Fernández-Calvo Ana Isabel , Plata Gorka , Lozares Jokin , Berlanga-Labari Carlos
Published: July 2021

The use of secondary aluminium is increasingly being promoted in the automotive industry for environmental reasons. The purpose of this study was to demonstrate that it is possible to obtain a recycled AlSi10MnMg(Fe) aluminium alloy with equal metallurgical quality to that of a primary AlSi10MnMg alloy when an adequate melt treatment is applied. The melt treatment consisted of deoxidation, degassing and skimming in accordance with the detailed procedure described in this article. The metallurgical qualities of one primary and two secondary alloys were assessed using thermal analysis, the density index test, the macroinclusion test and the microinclusion level test before and after melt treatment. The thermal analysis allowed us to compare the variables of the solidification cooling curve (Al primary temperature and its undercooling; Al-Si eutectic temperature and its predictive modification rate). The density index test was used to evaluate the hydrogen gas content in the melt. The macroinclusion test was used to evaluate the melt cleanliness, while the microinclusion level test was used to perform the inclusion identification and quantification analyses. This study showed the feasibility of manufacturing structural components using 100% recycled secondary aluminium alloy through V-HPDC technology.
Leaching Behavior of Lithium-Bearing Bauxite with High-Temperature Bayer Digestion Process in K2O-Al2O3-H2O System
Authors: Han Dongzhan , Peng Zhihong , Song Erwei , Shen Leiting
Published: July 2021

Lithium is one of the secondary mineral elements occurring in bauxite. The behavior of lithium-bearing bauxite in the digestion process was investigated, and the effect of digestion conditions on the extraction rates of lithium was studied. The results demonstrate that the mass ratio of the added CaO to bauxite, the KOH concentration, and the digestion temperature had a significant effect on the lithium extraction efficiency. An L9(34) orthogonal experiment demonstrated that the order of each factor for lithium extraction from primary to secondary is lime dosage, caustic concentration, and reaction temperature. Under the optimal conditions (t = 60 min, T = 260 °C, ρ(K2O) = 280 g/L, and 16% lime dosage), the leaching efficiencies of lithium and alumina are 85.6% and 80.09%, respectively, with about 15% of lithium entering into red mud. The findings of this study maybe useful for controlling lithium content in alumina products and lithium recovery from the Bayer process.
Cyclohumulanoid Sesquiterpenes from the Culture Broth of the Basidiomycetous Fungus Daedaleopsis tricolor
Authors: Kanehara Ryuhi , Tonouchi Akio , Konno Katsuhiro , Hashimoto Masaru
Published: July 2021

A series of cyclohumulanoids, i.e., tricocerapicanols A–C (1a–1c), tricoprotoilludenes A (2a) and B (3), tricosterpurol (4), and tricoilludins A–C (5–7) were isolated along with known violascensol (2b) and omphadiol (8) from the culture broth of Daedaleopsis tricolor, an inedible but not toxic mushroom. The structures were fully elucidated on the basis of NMR spectroscopic analysis, and the suggested relative structures were confirmed via density functional theory (DFT)-based chemical shift calculations involving a DP4 probability analysis. In the present study, the 1H chemical shifts were more informative than the 13C chemical shifts to distinguish the diastereomers at C-11. The absolute configurations of 1–5 were determined by comparing the experimental and calculated electronic circular dichroism (ECD) spectra. For 6 and 7, the same chirality was assigned according to their biosynthetic similarities with the other compounds. The successful assignment of some Cotton effects was achieved by utilizing DFT calculations using simple model compounds. The plausible biosynthesis of 1–7 was also discussed on the basis of the structural commonality and general cyclohumulanoid biosynthesis. Compounds 2a and 5 were found to simultaneously induce hyphal swelling and branching at 5.0 μg/mL against a test fungus Cochliobolus miyabeanus.
Syntheses and Study of a Pyrroline Nitroxide Condensed Phospholene Oxide and a Pyrroline Nitroxide Attached Diphenylphosphine
Authors: Isbera Mostafa , Bognár Balázs , Gallyas Ferenc , Bényei Attila , Jekő József , Kálai Tamás
Published: July 2021

The reaction of a diene nitroxide precursor with dichlorophenylphosphine in a McCormac procedure afforded 1,1,3,3-tetramethyl-5-phenyl-1,2,3,4,5,6-hexahydrophospholo[3,4-c]pyrrole-5-oxide-2-oxyl. Lithiation of the protected 3-iodo-pyrroline nitroxide followed by treatment with chlorodiphenylphosphine after deprotection afforded (1-oxyl-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-yl)diphenylphosphine oxide, and after reduction, (1-oxyl-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-yl)diphenylphosphine was realized, which was also supported by X-ray single crystal diffraction measurements. This pyrroline diphenylphosphine derivative was converted to hexadecylphosphonium salt, which is an analogue of antineoplastic agent, MITO-CP.
Evaluation of Antiproliferative Palladium(II) Complexes of Synthetic Bisdemethoxycurcumin towards In Vitro Cytotoxicity and Molecular Docking on DNA Sequence
Authors: Miklášová Natalia , Herich Peter , Dávila-Becerril Juan Carlos , Barroso-Flores Joaquín , Fischer-Fodor Eva , Valentová Jindra , Leskovská Janka , Kožíšek Jozef , Takáč Peter , Mojžiš Ján
Published: July 2021

Metallodrugs form a large family of therapeutic agents against cancer, among which is cisplatin, a paradigmatic member. Therapeutic resistance and undesired side effects to Pt(II) related drugs, prompts research on different metal–ligand combinations with potentially enhanced biological activity. We present the synthesis and biological tests of novel palladium(II) complexes containing bisdemethoxycurcumin (BDMC) 1 and 2. Complexes were fully characterized and their structures were determined by X-ray diffraction. Their biological activity was assessed for several selected human tumor cell lines: Jurkat (human leukaemic T-cell lymphoma), HCT-116 (human colorectal carcinoma), HeLa (human cervix epitheloid carcinoma), MCF-7 (human breast adenocarcinoma), MDA-MB-231 (human mammary gland adenocarcinoma), A549 (human alveolar adenocarcinoma), Caco-2 (human colorectal carcinoma), and for non-cancerous 3T3 cells (murine fibroblasts). The cytotoxicity of 1 is comparable to that of cisplatin, and superior to that of 2 in all cell lines. It is a correlation between IC50 values of 1 and 2 in the eight studied cell types, promising a potential use as anti-proliferative drugs. Moreover, for Jurkat cell line, complexes 1 and 2, show an enhanced activity. DFT and docking calculations on the NF-κB protein, Human Serum Albumin (HSA), and DNA were performed for 1 and 2 to correlate with their biological activities.
Synthesis, Biological and In Silico Studies of a Tripodal Schiff Base Derived from 2,4,6-Triamino-1,3,5-triazine and Its Trinuclear Dy(III), Er(III), and Gd(III) Salen Capped Complexes
Authors: Oruma Uchechukwu Susan , Ukoha Pius Oziri , Uzoewulu Chiamaka Peace , Ndefo Joseph Chinedum , Ugwuoke Sabastine Chinweike , Ukwueze Nkechinyere Nwanneka , Eze Tochukwu Emmanuella , Ekowo Lilian Chinenye , Eze Florence Uchenna , Chinaegbomkpa Uchenna Vivian , Okafor Sunday Nwankwo , Ezeorah Chigozie Julius
Published: July 2021

A tripodal Schiff base ligand, 2,4,6-Tris(4-carboxybenzimino)-1,3,5-triazine (MT) and its trinuclear Dy(III), Er(III), and Gd(III) complexes were synthesized. These were characterized using UV-visible, IR, 1H, and 13C NMR spectroscopies, elemental analysis, and molar conductivity measurements. The spectral studies indicate that the ligand is hexadentate and coordinates to the Ln(III) ions through the oxygen atoms of the carboxylic group. The trinuclear complexes were characterized as being bridged by carboxylate anions to the Dy(III), Er(III), and Gd(III) salen centers and displaying a coordination number of six. Biological studies revealed that MT is more active against the test micro-organisms relative to the trinuclear complexes. Acute toxicity studies revealed that MT is safe and has a wide range of effective doses (ED50). In vivo antimalarial studies indicate that MT could serve as an effective antimalarial agent since it has parasitemia inhibition of 84.02% at 50 mg/kg and 65.81% at 25 mg/kg, close to the value (87.22%) of the standard drug—Artesunate. Molecular docking simulation studies on the compounds against SARS-CoV-2 (6Y84) and E. coli DNA gyrase (5MMN) revealed effective binding interactions through multiple bonding modes. The binding energy calculated for Er(III)MT-6Y84 and Er(III)MT-5MMN complexes showed active molecules with the ability to inhibit SARS-CoV-2 and E. coli DNA gyrase.
Nanomaterials in Water Applications: Adsorbing Materials for Fluoride Removal
Authors: Huang Lei , Wan Kuilin , Yan Jia , Wang Lei , Li Qian , Chen Huabin , Zhang Hongguo , Xiao Tangfu
Published: July 2021

Fluoride is an important pollutant in many countries, such as China, India, Australia, the United States, Ethiopia, etc [...]
SARS-CoV-2 Infection Causes Relapse of Kleine-Levin Syndrome: Case Report and Review of Literature
Authors: Marčić Marino , Marčić Ljiljana , Marčić Barbara
Published: July 2021

Recurrent episodes of hypersomnia, hypersexuality, compulsive eating, behavioral and cognitive disturbances, are the basic clinical features of Kleine-Levin syndrome (KLS). Our case report describes a patient who was diagnosed with KLS at the age of 20. With appropriate therapy, the disease had a satisfactory course until patient had a moderate form of SARS-CoV-2 infection, which led to a significant exacerbation of all symptoms. SARS-CoV-2 virus can cause almost any neurological disease, and relapse of KLS is another evidence of neurotropicity of the virus.
Shallow-Water Species Diversity of Common Intertidal Zoantharians (Cnidaria: Hexacorallia: Zoantharia) along the Northeastern Coast of Trinidad, Southern Caribbean
Authors: Belford Stanton
Published: July 2021

Zoantharians are colonial cnidarians commonly found in shallow tropical Caribbean coral reefs, and are known to be globally distributed. Common species in genera Zoanthus and Palythoa occur at Toco, Trinidad, where they are more abundant than their Scleractinia counterparts relative to benthic coverage. In this study, distribution, morphological and molecular data were collected to determine species and symbiont identification to provide more insight on zoantharians. The Line Intercept Point (LIT) transect method recorded coverage at three sites: Salybia (SB), Pequelle (PB), and Grande L’Anse (GA) Bays along the northeastern coast. Variations in morphology, such as tentacle count, oral disk color and diameter were collected from colonies in situ. All specimens were zooxanthellate, and molecular and phylogenetic analyses were done by sequencing the cytochrome oxidase subunit I (COI) gene, and the internal transcribed spacer (ITS) region for species and symbiont identification, respectively. Results showed mean Zoantharia percentage cover was 32.4% ± 5.1 (X ± SE) at SB, 51.3% ± 6.5 (PB), and 72.2% ± 6.1 at GA. Zooxanthellate zoantharians were identified as Palythoa caribaeorum, Palythoa grandiflora, Zoanthus pulchellus, and Zoanthus sociatus. Symbiodiniaceae genera were identified as Cladocopium and Symbiodinium in Palythoa and Zoanthus spp., respectively. Although this is the first molecular examination of zoantharians, and their symbionts in Trinidad, more research is needed to identify and document species distribution and symbiont biodiversity to understand their ecology in these dynamic ecosystems.
Development of Machine Learning Models for Accurately Predicting and Ranking the Activity of Lead Molecules to Inhibit PRC2 Dependent Cancer
Authors: Danishuddin  , Kumar Vikas , Parate Shraddha , Bahuguna Ashutosh , Lee Gihwan , Kim Myeong Ok , Lee Keun Woo
Published: July 2021

Disruption of epigenetic processes to eradicate tumor cells is among the most promising interventions for cancer control. EZH2 (Enhancer of zeste homolog 2), a catalytic component of polycomb repressive complex 2 (PRC2), methylates lysine 27 of histone H3 to promote transcriptional silencing and is an important drug target for controlling cancer via epigenetic processes. In the present study, we have developed various predictive models for modeling the inhibitory activity of EZH2. Binary and multiclass models were built using SVM, random forest and XGBoost methods. Rigorous validation approaches including predictiveness curve, Y-randomization and applicability domain (AD) were employed for evaluation of the developed models. Eighteen descriptors selected from Boruta methods have been used for modeling. For binary classification, random forest and XGBoost achieved an accuracy of 0.80 and 0.82, respectively, on external test set. Contrastingly, for multiclass models, random forest and XGBoost achieved an accuracy of 0.73 and 0.75, respectively. 500 Y-randomization runs demonstrate that the models were robust and the correlations were not by chance. Evaluation metrics from predictiveness curve show that the selected eighteen descriptors predict active compounds with total gain (TG) of 0.79 and 0.59 for XGBoost and random forest, respectively. Validated models were further used for virtual screening and molecular docking in search of potential hits. A total of 221 compounds were commonly predicted as active with above the set probability threshold and also under the AD of training set. Molecular docking revealed that three compounds have reasonable binding energy and favorable interactions with critical residues in the active site of EZH2. In conclusion, we highlighted the potential of rigorously validated models for accurately predicting and ranking the activities of lead molecules against cancer epigenetic targets. The models presented in this study represent the platform for development of EZH2 inhibitors.
Temperate UV-Accelerated Weathering Cycle Combined with HT-GPC Analysis and Drop Point Testing for Determining the Environmental Instability of Polyethylene Films
Authors: Moreira Celine , Lloyd Richard , Hill Gavin , Huynh Florence , Trufasila Ana , Ly Faith , Sawal Hasan , Wallis Christopher
Published: July 2021

Polyethylene films are one of the most frequently used packaging materials in our society, due to their combination of strength and flexibility. An unintended consequence of this high use has been the ever-increasing accumulation of polyethylene films in the natural environment. Previous attempts to understand their deterioration have either focused on their durability using polymer analysis; or they have focused on changes occurring during outdoor exposure. Herein, this study combines those strategies into one, by studying the chemical and physical changes in the polyethylene structure in a laboratory using molecular weight and IR spectroscopic mapping analysis, combined with temperate UV-accelerated weathering cycles. This approach has been correlated to real-world outdoor exposure timeframes by parallel testing of the sample polyethylene films in Florida and France. The formation of polyethylene microparticles or polyethylene waxes is elucidated through comparison of drop point testing and molecular weight analysis.
Metal-Based Nanocomposite Materials for Efficient Photocatalytic Degradation of Phenanthrene from Aqueous Solutions
Authors: Chauhan Husn Ara , Rafatullah Mohd. , Ahmed Ali Khozema , Siddiqui Masoom Raza , Khan Moonis Ali , Alshareef Shareefa Ahmed
Published: July 2021

Polycyclic aromatic hydrocarbons (PAHs) are a class of naturally occurring chemicals resulting from the insufficient combustion of fossil fuels. Among the PAHs, phenanthrene is one of the most studied compounds in the marine ecosystems. The damaging effects of phenanthrene on the environment are increasing day by day globally. To lessen its effect on the environment, it is essential to remove phenanthrene from the water resources in particular and the environment in general through advanced treatment methods such as photocatalytic degradation with high-performance characteristics and low cost. Therefore, the combination of metals or amalgamation of bimetallic oxides as an efficient photocatalyst demonstrated its propitiousness for the degradation of phenanthrene from aqueous solutions. Here, we reviewed the different nanocomposite materials as a photocatalyst, the mechanism and reactions to the treatment of phenanthrene, as well as the influence of other variables on the rate of phenanthrene degradation.
Cyclic Gas Dissolution Foaming as an Approach for Simultaneously Reducing Cell Size and Relative Density in Nanocellular PMMA
Authors: Martín-de León Judith , Bernardo Victoria , Rodriguez-Perez Miguel Ángel
Published: July 2021

A new approach to produce nanocellular polymers combining small cell sizes with low relative densities is presented herein. This production method, based on gas dissolution foaming, consists of performing a double saturation and foaming cycle. Thus, nanocellular polymethylmethacrylate (PMMA) has been produced through a first saturation at different saturation conditions (6, 10, and 20 MPa and −32 °C), at constant foaming conditions (60 °C for 1 min). Then, the nanocellular PMMAs obtained from the previous step were again saturated at different saturation conditions, 10 MPa 24 °C, 31 MPa 24 °C, 35 MPa 22 °C, and 6 MPa −15 °C and foamed at different temperatures (40, 80 and 100 °C) for 1 min. This new approach allows the cells created in the first saturation and foaming cycle to further grow in the second cycle. This fact permits producing nanocellular polymethylmethacrylate sheets combining, for the first time in the literature, cell sizes of 24 nm with relative densities of 0.3.
Identifying Optimal Wavelengths as Disease Signatures Using Hyperspectral Sensor and Machine Learning
Authors: Wei Xing , Johnson Marcela A. , Langston David B. , Mehl Hillary L. , Li Song
Published: July 2021

Hyperspectral sensors combined with machine learning are increasingly utilized in agricultural crop systems for diverse applications, including plant disease detection. This study was designed to identify the most important wavelengths to discriminate between healthy and diseased peanut (Arachis hypogaea L.) plants infected with Athelia rolfsii, the causal agent of peanut stem rot, using in-situ spectroscopy and machine learning. In greenhouse experiments, daily measurements were conducted to inspect disease symptoms visually and to collect spectral reflectance of peanut leaves on lateral stems of plants mock-inoculated and inoculated with A. rolfsii. Spectrum files were categorized into five classes based on foliar wilting symptoms. Five feature selection methods were compared to select the top 10 ranked wavelengths with and without a custom minimum distance of 20 nm. Recursive feature elimination methods outperformed the chi-square and SelectFromModel methods. Adding the minimum distance of 20 nm into the top selected wavelengths improved classification performance. Wavelengths of 501–505, 690–694, 763 and 884 nm were repeatedly selected by two or more feature selection methods. These selected wavelengths can be applied in designing optical sensors for automated stem rot detection in peanut fields. The machine-learning-based methodology can be adapted to identify spectral signatures of disease in other plant-pathogen systems.
Exploring the Impacts and Temporal Variations of Different Building Roof Types on Surface Urban Heat Island
Authors: Deng Yingbin , Chen Renrong , Xie Yichun , Xu Jianhui , Yang Ji , Liao Wenyue
Published: July 2021

This study examined the impact of different types of building roofs on urban heat islands. This was carried out using building roof data from remotely sensed Landsat 8 Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) imagery. The roofs captured included white surface, blue steel, dark metal, other dark material, and residential roofs; these roofs were compared alongside three natural land covers (i.e., forest trees, grassland, and water). We also collected ancillary data including building height, building density, and distance to the city center. The impacts of various building roofs on land surface temperature (LST) were examined by analyzing their correlation and temporal variations. First, we examined the LST characteristics of five building roof types and three natural land covers using boxplots and variance analysis with post hoc tests. Then, multivariate regression analysis was used to explore the impact of building roofs on LST. There were three key findings in the results. First, the mean LSTs for five different building roofs statistically differed from each other; these differences were more significant during the hot season than the cool season. Second, the impact of the five types of roofs on LSTs varied considerably from each other. Lastly, the contribution of the five roof types to LST variance was more substantial during the cool season. These findings unveil specific urban heat retention drivers, in which different types of building roofs are one such driver. The outcomes from this research may help policymakers develop more effective strategies to address the surface urban heat island phenomenon and its related health concerns.
Improving CyGNSS-Based Land Remote Sensing: Track-Wise Data Calibration Schemes
Authors: Yan Qingyun , Hu Ting , Jin Shuanggen , Huang Weimin , Jia Yan , Chen Tiexi , Wang Jian
Published: July 2021

Cyclone Global Navigation Satellite System (CyGNSS) data have been used for generating several intermediate products, such as surface reflectivity (Γ), to facilitate a wide variety of land remote sensing applications. The accuracy of Γ relies on precise knowledge of the effective instantaneous radiative power (EIRP) of the transmitted GNSS signals in the direction of the specular reflection point, the precise knowledge of zenith antenna patterns which in turn affects estimates of EIRP, the good knowledge of receive antenna patterns etc. However, obtaining accurate estimates on these parameters completely is still a challenge. To solve this problem, in this paper, an effective method is proposed for calibrating the CyGNSS Γ product in a track-wise manner. Here, two different criteria for selecting data to calibrate and three reference options as targets of the calibrating data are examined. Accordingly, six calibration schemes corresponding to six different combinations are implemented and the resulting Γ products are assessed by (1) visual inspection and (2) evaluation of their associated soil moisture retrieval results. Both visual inspection and retrieval validation demonstrate the effectiveness of the proposed schemes, which are respectively demonstrated by the immediate removal/fix of track-wisely noisy data and obvious enhancement of retrieval accuracy with the calibrated Γ. Moreover, the schemes are tested using all the available CyGNSS level 1 version 3.0 data and the good results obtained from such a large volume of data further illustrate their robustness. This work provides an effective and robust way to calibrate the CyGNSS Γ result, which will further improve relevant remote sensing applications in the future.
Retrieving Doppler Frequency via Local Correlation Method of Segmented Modeling
Authors: Chen Lue , Ping Jinsong , Cao Jianfeng , Liu Xiang , Wang Na , Wang Zhen , Zhu Ping , Wang Mei , Man Haijun , Fan Fei , Lu Weitao , Sun Jing , Han Songtao
Published: July 2021

The high accuracy radio Doppler frequency is critical for navigating a deep space probe and for planetary radio science experiments. In this paper, we propose a novel method based on the local correlation of segmented modeling to retrieve Doppler frequency by processing an open-loop radio link signal from one single ground station. Simulations are implemented, which prove the validity of this method. Mars Express (MEX) and Tianwen-1 observation experiments were carried out by Chinese Deep Space Stations (CDSS). X-band Doppler frequency observables were retrieved by the proposed method to participate in orbit determination. The results show that the accuracy of velocity residuals of orbit determination in open-loop mode is from 0.043 mm/s to 0.061 mm/s in 1 s integration; the average accuracy of Doppler frequency is about 3.3 mHz in 1 s integration and about 0.73 mHz in 60 s integration. The Doppler accuracy here is better than that of the digital baseband receiver at CDSS. The algorithm is efficient and flexible when the deep space probe is in a high dynamic mode and in low signal to noise ratio (SNR). This will benefit Chinese deep space exploration missions and planetary radio science experiments.
A Quadruped Robot with Three-Dimensional Flexible Legs
Authors: Huang Wenkai , Xiao Junlong , Zeng Feilong , Lu Puwei , Lin Guojian , Hu Wei , Lin Xuyu , Wu Yu
Published: July 2021

As an important part of the quadruped robot, the leg determines its performance. Flexible legs or flexible joints aid in the buffering and adaptability of robots. At present, most flexible quadruped robots only have two-dimensional flexibility or use complex parallel structures to achieve three-dimensional flexibility. This research will propose a new type of three-dimensional flexible structure. This passive compliant three-dimensional flexibility reduces the weight and complex structure of the robot. The anti-impact performance of the robot is verified by a side impact experiment. The simulation and experiments show that the robot still has good stability even under a simple algorithm and that the flexible leg can reduce the impact on the quadruped robot and improve the environmental adaptability of the robot.
Solid-Contact Electrode with Composite PVC-Based 3D-Printed Membrane. Optimization of Fabrication and Performance
Authors: Bartoszewicz Bartosz , Lewenstam Andrzej , Migdalski Jan
Published: July 2021

Intense interest in reference electrode design and fabrication has recently been enriched with the application of 3D printing of electrodes with salt-loaded PVC membranes. This type of material is attractive in sensor technology and is challenging to implement in 3D. In this report, several improvements and simplifications in the technology were focused on and supported by a fundamental electrochemical characterization.
Joining of Electrodes to Ultra-Thin Metallic Layers on Ceramic Substrates in Cryogenic Sensors
Authors: Lebioda Marcin , Pawlak Ryszard , Rymaszewski Jacek
Published: July 2021

Microjoining technologies are crucial for producing reliable electrical connections in modern microelectronic and optoelectronic devices, as well as for the assembly of electronic circuits, sensors, and batteries. However, the production of miniature sensors presents particular difficulties, due to their non-standard designs, unique functionality and applications in various environments. One of the main challenges relates to the fact that common methods such as reflow soldering or wave soldering cannot be applied to making joints to the materials used for the sensing layers (oxides, polymers, graphene, metallic layers) or to the thin metallic layers that act as contact pads. This problem applies especially to sensors designed to work at cryogenic temperatures. In this paper, we demonstrate a new method for the dynamic soldering of outer leads in the form of metallic strips made from thin metallic layers on ceramic substrates. These leads can be used as contact pads in sensors working in a wide temperature range. The joints produced using our method show excellent electrical, thermal, and mechanical properties in the temperature range of 15–300 K.
Design of Double-Layer Electrically Extremely Small-Size Displacement Sensor
Authors: Wang Yi-Dong , Han Feng-Yuan , Zhao Jin , Zhang Zi-Wen , Wang Di , Tan Yun-Hua , Liu Pu-Kun
Published: July 2021

In this paper, a displacement sensor with an electrically extremely small size and high sensitivity is proposed based on an elaborately designed metamaterial element, i.e., coupled split-ring resonators (SRRs). The sensor consists of a feeding structure with a rectangular opening loop and a sensing structure with double-layer coupled SRRs. The movable double-layer structures can be used to measure the relative displacement. The size of microwave displacement sensors can be significantly reduced due to the compact feeding and sensing structures. By adjusting the position of the split gap within the resonator, the detection directions of the displacement sensing can be further expanded accordingly (along with the x- or y-axis) without increasing its physical size. Compared with previous works, the extremely compact size of 0.05λ0 × 0.05λ0 (λ0 denotes the free-space wavelength), a high sensitivity, and a high quality factor (Q-factor) can be achieved by the proposed sensor. From the perspective of the advantages above, the proposed sensor holds promise for being applied in many high-precision industrial measurement scenarios.